JP7520197B2 - Optical laminate and method for producing same - Google Patents

Description

The present invention relates to an optical laminate and a method for producing the same.

A circular polarizing plate containing a polarizing element and a retardation element is known as an optical laminate having anti-reflection properties. Retardation elements contained in a circular polarizing plate include a λ/4 layer and a λ/2 layer (for example, Patent Document 1). A circular polarizing plate can be obtained, for example, by laminating a polarizing plate containing a polarizing element and a retardation body in which a λ/4 layer and a λ/2 layer are laminated, via a pressure-sensitive adhesive.

JP 2020-52365 A

In order to meet the demand for thinner circular polarizers applied to displays such as organic EL displays, a liquid crystal retardation layer having a polymer layer, which is a layer of a polymer of a polymerizable liquid crystal compound, may be used as a retardation element. The polymer layer of the liquid crystal retardation layer can be obtained by forming a coating layer by applying a composition containing a polymerizable liquid crystal compound onto a base layer or an alignment layer formed on the base layer, and irradiating the coating layer with active energy rays to polymerize the polymerizable liquid crystal compound. When a heat shock test was performed on a circular polarizer provided with a liquid crystal retardation layer having a polymer layer, cracks (breaks) sometimes occurred in the liquid crystal retardation layer.

The present invention provides an optical laminate and a manufacturing method thereof that can suppress cracks from occurring in the liquid crystal retardation layer even when a heat shock test is performed.

The present invention provides the following optical laminate and a method for producing the same.
[1] An optical laminate including a polarizing plate including a polarizing element, a pressure-sensitive adhesive layer, and a first liquid crystal retardation layer in this order,
The first liquid crystal retardation layer is a first polymer layer containing a polymer of a polymerizable liquid crystal compound, or a multilayer body of the first polymer layer and a first alignment layer,
A ratio (H1/H2) of a surface hardness (H1) of a first surface of the first liquid crystal retardation layer to a surface hardness (H2) of a second surface of the first liquid crystal retardation layer opposite to the first surface is 0.90 or more and 1.10 or less.
[2] The optical laminate according to [1], wherein the product of the indentation elastic modulus of the adhesive layer at a temperature of 23° C. and the thickness of the adhesive layer is 300 MPa·μm or more.
[3] The optical laminate according to [1] or [2], wherein the first liquid crystal retardation layer is the first polymer layer.
[4] The optical laminate according to any one of [1] to [3], wherein the polarizing element is a polarizer containing a polyvinyl alcohol-based resin and boron.
[5] The optical laminate according to any one of [1] to [4], wherein the first liquid crystal retardation layer is a ½ liquid crystal retardation layer or a ¼ liquid crystal retardation layer.
[6] The optical laminate further includes a second liquid crystal retardation layer between the pressure-sensitive adhesive layer and the first liquid crystal retardation layer,
The second liquid crystal retardation layer is a second polymer layer containing a polymer of a polymerizable liquid crystal compound, or a multilayer body of the second polymer layer and a second alignment layer, [1] to [5]. The optical laminate according to any one of the above.
[7] The optical laminate according to [6], wherein a laminate of the first liquid crystal retardation layer and the second liquid crystal retardation layer satisfies the relationship of the following formulas (1)' and (2)'.
100≦Re(550)≦180 (1)'
Re(450)/Re(550)≦1.00 (2)'
[In formula (1)′ and formula (2)′,
Re(450) represents an in-plane retardation value for light having a wavelength of 450 nm;
Re(550) represents an in-plane retardation value for light having a wavelength of 550 nm.]
[8] The optical laminate according to any one of [1] to [7], wherein the polarizing plate has a polarizing element protective film on one or both sides of the polarizing element.
[9] Further, a base material layer is provided on the opposite side of the first liquid crystal retardation layer to the adhesive layer side,
The optical laminate according to any one of [1] to [8], wherein the base layer is in direct contact with the first liquid crystal retardation layer.
[10] A method for producing an optical laminate including a polarizing plate including a polarizing element, a pressure-sensitive adhesive layer, and a first liquid crystal retardation layer in this order, comprising:
The first liquid crystal retardation layer is a first polymer layer containing a polymer of a polymerizable liquid crystal compound, or a multilayer body of the first polymer layer and a first alignment layer,
The manufacturing method includes:
A step (S1) of obtaining a substrate-attached coating layer having the substrate layer and the coating layer by applying a liquid crystal retardation layer forming composition containing a polymerizable liquid crystal compound onto the substrate layer or onto the first alignment layer formed on the substrate layer;
and (S2) irradiating both surfaces of the substrate-attached coating layer with active energy rays to polymerize the polymerizable liquid crystal compound in the coating layer to form the first polymer layer.
[11] The active energy ray is ultraviolet ray,
The method for producing an optical laminate according to [10], wherein the total integrated light amount of the ultraviolet light irradiated to both sides of the substrate-attached coating layer in the step (S2) is 10 mJ/cm ² or more and 3000 mJ/cm ² or less.
[12] Further, a step of obtaining an optical laminate with a substrate, the optical laminate including the polarizing plate, the pressure-sensitive adhesive layer, the first liquid crystal retardation layer, and the substrate layer in this order;
The method for producing the optical laminate according to [10] or [11], comprising a step of peeling off the base layer from the optical laminate with a base.
[13] The substrate-attached optical laminate further includes a second liquid crystal retardation layer between the pressure-sensitive adhesive layer and the first liquid crystal retardation layer,
The second liquid crystal retardation layer is a second polymer layer containing a polymer of a polymerizable liquid crystal compound, or a multilayer body of the second polymer layer and a second alignment layer. [12] The method for producing an optical laminate.

The present invention provides an optical laminate that can suppress cracks from occurring in the liquid crystal retardation layer even when a heat shock test is performed.

FIG. 1 is a cross-sectional view that illustrates an optical laminate according to one embodiment of the present invention. FIG. 2 is a cross-sectional view illustrating an optical laminate according to another embodiment of the present invention. 1A to 1C are cross-sectional views that diagrammatically show a manufacturing process for an optical laminate according to one embodiment of the present invention. 5A to 5C are cross-sectional views illustrating a manufacturing process of an optical laminate according to another embodiment of the present invention.

Below, preferred embodiments of the optical laminate and the method for manufacturing the optical laminate will be described with reference to the drawings.

<Optical laminate>
1 and 2 are cross-sectional views each showing a schematic diagram of an optical laminate according to an embodiment of the present invention. As shown in FIG. 1 and FIG. 2, the optical laminate 1, 2 includes a polarizing plate 50 including a polarizing element, a first adhesive layer 31 (adhesive layer), and a first liquid crystal retardation layer 11 in this order. In the optical laminate 1, 2, it is preferable that the polarizing plate 50 and the first adhesive layer 31 are in direct contact with each other. In the optical laminate 1, 2, the polarizing plate 50 side is usually the viewing side.

As shown in FIG. 2, the optical laminate 2 includes a second liquid crystal retardation layer 21 between the first adhesive layer 31 and the first liquid crystal retardation layer 11. The first liquid crystal retardation layer 11 and the second liquid crystal retardation layer 21 may be laminated in direct contact with each other, or may be laminated via a second adhesive layer 32 disposed between these two layers (FIG. 2). When the optical laminate 2 includes the second adhesive layer 32, it is preferable that the first liquid crystal retardation layer 11 and the second adhesive layer 32 are in direct contact with each other, and it is preferable that the second adhesive layer 32 and the second liquid crystal retardation layer 21 are in direct contact with each other.

As described later, the optical laminates 1 and 2 may have a first base layer 16 on the side opposite to the polarizing plate 50 side of the first liquid crystal retardation layer 11 (FIG. 3(c) and FIG. 4(d)). The first base layer 16 supports the first liquid crystal retardation layer 11 and is preferably in direct contact with the first liquid crystal retardation layer 11. The first base layer 16 is preferably peelable from the first liquid crystal retardation layer 11.

The optical laminates 1 and 2 can be used in display devices, etc., as described below.

(First liquid crystal retardation layer)
The first liquid crystal retardation layer 11 is a first polymer layer containing a polymer of a polymerizable liquid crystal compound, or a multilayer body of a first polymer layer and a first alignment layer. The polymer to be applied is usually a polymer obtained by polymerizing a polymerizable liquid crystal compound in an aligned state. The first liquid crystal retardation layer 11 is preferably a first polymer layer. The first polymer layer is preferably a polymer layer having a structure similar to that described later. The first polymer layer is formed from a first liquid crystal retardation layer forming composition (liquid crystal retardation layer forming composition) containing a polymerizable liquid crystal compound so as to form the first polymer layer. When the first liquid crystal retardation layer 11 includes a first alignment layer, the first polymer layer and the first alignment layer are usually in direct contact with each other. The first alignment layer is the first alignment layer of the first polymer layer. It may be disposed on the first adhesive layer 31 side, or on the side opposite to the first adhesive layer 31 side.

The ratio (H1/H2) of the surface hardness (H1) of the first surface of the first liquid crystal retardation layer 11 to the surface hardness (H2) of the second surface of the first liquid crystal retardation layer 11 opposite to the first surface is 0.90 or more and 1.10 or less. The ratio (H1/H2) is preferably 0.92 or more and 1.08 or less, more preferably 0.94 or more and 1.06 or less, and may be 0.95 or more and 1.05 or less. The first surface may be the surface of the first liquid crystal retardation layer 11 on the first adhesive layer 31 side, or may be the surface opposite to the first adhesive layer 31 side. The surface hardness of the first surface and the second surface can be measured by the method described in the examples below.

In the first liquid crystal retardation layer 11, by having the surface hardness ratio (H1/H2) in the above range, even when the optical laminates 1 and 2 are subjected to a heat shock test, the cracks occurring in the first liquid crystal retardation layer 11 can be suppressed. If the surface hardness ratio (H1/H2) is a value away from the above range, the hardness variation in the first liquid crystal retardation layer 11 increases. If the hardness variation in the first liquid crystal retardation layer 11 increases, cracks are likely to occur starting from relatively hard parts in the first liquid crystal retardation layer 11 when subjected to an external force such as a heat shock test. By bringing the surface hardness ratio (H1/H2) closer to the above range, the hardness variation in the first liquid crystal retardation layer 11 can be suppressed. This makes it possible to suppress the occurrence of cracks in the first liquid crystal retardation layer 11 subjected to an external force such as a heat shock test.

The surface hardness ratio (H1/H2) of the first liquid crystal retardation layer 11 can be adjusted by the manufacturing conditions of the first liquid crystal retardation layer 11, the layer structure of the first liquid crystal retardation layer 11, etc. Methods for adjusting the manufacturing conditions of the first liquid crystal retardation layer 11 include a method of using a highly flexible monomer as a polymerizable liquid crystal compound contained in the composition for forming the first liquid crystal retardation layer used to form the first liquid crystal retardation layer 11, a method of phase-separating additives and monomer components contained in the composition for forming the liquid crystal retardation layer, a method of adjusting the irradiation position of the active energy ray when forming the first polymer layer (described later), a method of adjusting the irradiation intensity of the active energy ray (described later), etc.

The first liquid crystal retardation layer 11 may be a λ/4 liquid crystal retardation layer having a λ/4 plate function, or a λ/2 liquid crystal retardation layer having a λ/2 plate function. The first liquid crystal retardation layer 11 may be a reverse wavelength dispersion λ/4 liquid crystal retardation layer. A more detailed description of the first liquid crystal retardation layer 11 will be given later.

(Second liquid crystal retardation layer)
The second liquid crystal retardation layer 21 is a second polymer layer containing a polymer of a polymerizable liquid crystal compound, or a multilayer body of a second polymer layer and a second alignment layer. The polymer formed is usually a polymer formed by polymerizing a polymerizable liquid crystal compound in an aligned state. The second polymer layer is formed from a second liquid crystal retardation layer forming composition containing a polymerizable liquid crystal compound as described later. The second polymer layer can be a layer that exhibits retardation. When the second liquid crystal retardation layer 21 includes a second alignment layer, the second polymer layer and the second alignment layer The second alignment layer may be disposed on the first adhesive layer 31 side of the second polymer layer, or on the first liquid crystal retardation layer 11 side. .

The ratio (H21/H22) between the surface hardness (H21) of the first surface of the second liquid crystal retardation layer 21 and the surface hardness (H22) of the second surface opposite to the first surface of the second liquid crystal retardation layer 21 is not particularly limited. The ratio (H21/H22) may be in the range described for the surface hardness ratio (H1/H2) of the first liquid crystal retardation layer 11 described above. This can suppress the occurrence of cracks in the second liquid crystal retardation layer 21 subjected to external forces such as a heat shock test. The surface hardness ratio (H21/H22) of the second liquid crystal retardation layer 21 can be adjusted by the manufacturing conditions of the second liquid crystal retardation layer 21, the layer structure of the second liquid crystal retardation layer 21, etc. A more detailed description of the second liquid crystal retardation layer 21 will be given later.

(First adhesive layer)
The first adhesive layer 31 is a pressure-sensitive adhesive layer or an adhesive layer. The first adhesive layer 31 is preferably a pressure-sensitive adhesive layer.

The product of the indentation modulus of the first adhesive layer 31 at a temperature of 23°C and the thickness of the first adhesive layer 31 is preferably 300 MPa·μm or more, may be 500 MPa·μm or more, may be 650 MPa·μm or more, may be 800 MPa·μm or more, may be 1000 MPa·μm or more, and is usually 5000 MPa·μm or less. When the product of the indentation modulus and the thickness of the first adhesive layer 31 is within the above range, the first adhesive layer 31 becomes hard and thick. In the optical laminates 1 and 2 including such a first adhesive layer 31, cracks occurring in the first liquid crystal retardation layer 11 can be further suppressed by a heat shock test.

The indentation modulus of the first adhesive layer 31 at a temperature of 23°C may be 1 MPa or more, 5 MPa or more, 50 MPa or more, 100 MPa or more, 130 MPa or more, and is usually 1000 MPa or less. The thickness of the first adhesive layer 31 may be 0.1 μm or more and 30 μm or less, 3 μm or more and 30 μm or less, or 5 μm or more and 25 μm or less. The indentation modulus and thickness of the first adhesive layer 31 can be measured by the method described in the examples below. A more detailed description of the first adhesive layer 31 will be given later.

(Second adhesive layer)
The product of the indentation elastic modulus of the second adhesive layer 32 at a temperature of 23° C. and the thickness of the second adhesive layer 32 may be in the range described above for the product of the indentation elastic modulus and the thickness of the first adhesive layer 31. The indentation elastic modulus and thickness of the second adhesive layer can also be measured in the same manner as the indentation elastic modulus and thickness of the first adhesive layer 31. A more detailed description of the second adhesive layer 32 will be given later.

(Polarizer)
The polarizing plate 50 may include a polarizing element, and may have a polarizing element and a polarizing element protective film provided on one or both sides of the polarizing element.

The polarizing element is preferably a polarizer containing a polyvinyl alcohol resin and boron. The boron content of the polarizer is preferably 0.5% by mass to 5.5% by mass, more preferably 1.0% by mass to 5.0% by mass, and even more preferably 2.0% by mass to 4.5% by mass. By having the boron content of the polarizer in the optical laminates 1 and 2 within the above range, the shrinkage of the polarizer in the heat shock test of the optical laminates 1 and 2 can be suppressed, and therefore the occurrence of cracks in the first liquid crystal retardation layer 11 can be further suppressed.

The boron content of the polarizer is the ratio of the mass of boron contained in the polarizer to the total mass of the polarizer, and can be determined by the method described in the examples described below. It is considered that boron in the polarizer exists in a free state as boric acid (H ₃ BO ₃ ), or exists in a state in which boron forms a crosslinked structure with a unit of a polyvinyl alcohol resin. In this specification, the boron content is the amount of boron atoms themselves, including those that exist in the form of a compound as described above. The boron content of the polarizer can be adjusted by the amount of boric acid used in the manufacturing method of the polarizer described below, or the treatment conditions with boric acid.

The contraction force per 2 mm width in the absorption axis direction of the polarizer when held at a temperature of 80°C for 4 hours may be 3.5 N/2 mm or less, or may be 3.0 N/2 mm or less, preferably 2.8 N/2 mm or less, more preferably 2.5 N/2 mm or less, even more preferably 2.3 N/2 mm or less, and is usually 0.5 N/2 mm or more. A more detailed description of the polarizing plate, polarizing element, and polarizer will be given later.

<Method of manufacturing optical laminate>
3 and 4 are cross-sectional views that typically show a manufacturing process of an optical laminate according to one embodiment of the present invention.
A step (S1) of obtaining a substrate-attached first coating layer (substrate-attached coating layer) 12 having a first substrate layer 16 and a first coating layer 18 by applying a composition for forming a first liquid crystal retardation layer containing a polymerizable liquid crystal compound onto a first substrate layer 16 or a first alignment layer 17 formed on the first substrate layer 16 ((a) of FIG. 3 );
and a step (S2) of irradiating both sides of the substrate-attached first coating layer 12 with active energy rays to polymerize the polymerizable liquid crystal compound in the first coating layer 18 to form a first polymer layer.

By irradiating both sides of the substrate-attached first coating layer 12 with active energy rays (i.e., by irradiating the active energy rays toward both surfaces of the substrate-attached first coating layer 12), the surface hardness ratio (H1/H2) of the first liquid crystal retardation layer 11 can be easily adjusted to the above-mentioned range. When irradiating the active energy rays only from the first coating layer 12 side of the substrate-attached first coating layer 12, a method of reducing the irradiation intensity of the active energy rays irradiated to the first coating layer 12 side is considered as a method of adjusting the surface hardness ratio (H1/H2) of the first liquid crystal retardation layer 11 to the above-mentioned range. In this case, the degree of crosslinking on the first substrate layer 16 side of the first coating layer 12 is reduced, so that the surface hardness of the first polymer layer on the first substrate layer 16 side is reduced. Therefore, in the manufacturing method of this embodiment, the active energy rays are also irradiated from the first substrate layer 16 side in order to increase the degree of crosslinking on the first substrate layer 16 side of the first coating layer 12 and increase the surface hardness of the surface side of the first polymer layer on the first substrate layer 16 side. This allows the surface hardness of both sides of the first polymer layer to approach the same value, making it easier to adjust the surface hardness ratio (H1/H2) of the first liquid crystal retardation layer 11 to the above range. This makes it possible to suppress cracks from occurring in the first liquid crystal retardation layer 11 even when a heat shock test is performed on the optical laminates 1 and 2.

The cumulative light amount of the active energy rays irradiated to both sides of the substrate-attached first coating layer 12 may be the same or different on both sides, but it is preferable to irradiate so that the cumulative light amount of the active energy rays irradiated from the first substrate layer 16 side of the substrate-attached first coating layer 12 is greater than the cumulative light amount of the active energy rays irradiated from the first coating layer 18 side. The cumulative light amount of the active energy rays irradiated from the first substrate layer 16 side of the substrate-attached first coating layer 12 may be, for example, 1.1 times or more, 1.3 times or more, or 1.5 times or more, and is usually 2.0 times or less, of the cumulative light amount of the active energy rays irradiated from the first coating layer 18 side. By irradiating the active energy rays to both sides of the substrate-attached first coating layer 12, the amount of the active energy rays irradiated to the first coating layer 12 side can also be reduced compared to the case where the active energy rays are irradiated only from the first coating layer 12 side of the substrate-attached first coating layer 12. By increasing the cumulative amount of active energy rays irradiated from the first base layer 16 side, the effects of heat wrinkles and the like can be suppressed, and by irradiating both sides, the surface hardness of the first polymer layer on the first base layer 16 side can be increased, making it easier to adjust the surface hardness ratio (H1/H2) of the first liquid crystal retardation layer 11 to the above range.

Methods of irradiating active energy rays to both sides of the substrate-attached first coating layer 12 include irradiating both sides of the substrate-attached first coating layer 12 simultaneously, irradiating each side alternately, repeatedly irradiating both sides simultaneously, repeatedly irradiating each side alternately, or any combination of these.

The active energy rays to be irradiated to the substrate-attached first coating layer 12 are appropriately selected according to the type of polymerizable liquid crystal compound contained in the first coating layer 18 (particularly the type of polymerizable functional group possessed by the polymerizable liquid crystal compound), the type of photopolymerization initiator if a photopolymerization initiator is contained, and the amount thereof. Specific examples include one or more types of active energy rays selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays. As the active energy rays, ultraviolet light is preferred.

When the active energy rays irradiated in step (S2) are ultraviolet rays, the total integrated light amount of the ultraviolet rays irradiated to both sides of the substrate-attached first coating layer 18 is usually 10 mJ/ ^cm2 or more and 3,000 mJ/ ^cm2 or less, preferably 50 mJ/ ^cm2 or more and 2,000 mJ/ ^cm2 or less, and more preferably 100 mJ/ ^cm2 or more and 1,000 mJ/ ^cm2 or less.

When the active energy rays irradiated in step (S2) are ultraviolet rays, it is preferable that the first substrate layer 16 has excellent ultraviolet transmittance, as described below, so that the ultraviolet rays irradiated from the first substrate layer 16 side of the substrate-attached first coating layer 18 can efficiently reach the first coating layer 18.

The method for producing the optical laminates 1 and 2 includes the steps of:
Further, there is a step (S3) of obtaining a substrate-attached optical laminate 3, 4 including a polarizing plate 50, a first adhesive layer 31, a first liquid crystal retardation layer 11, and a first substrate layer 16 in this order (FIG. 3(c) and FIG. 4(d)),
The method may also include a step (S4) of peeling off the first base layer 16 from the substrate-attached optical laminates 3 and 4.

In step (S3), as shown in (b) and (c) of FIG. 3, the substrate-attached first liquid crystal retardation layer 13 having the first liquid crystal retardation layer 11 on the first substrate layer 16 obtained in step (S2) and the polarizing plate 50 are laminated via the first adhesive layer 31 to obtain the substrate-attached optical laminate 3. When the first liquid crystal retardation layer 11 is a multilayer body, the substrate-attached optical laminate 3 is usually arranged such that the first polymer layer is disposed on the first adhesive layer 31 side and the first alignment layer is disposed on the first substrate layer 16 side.

As shown in FIG. 4(d), the substrate-attached optical laminate 4 may further include a second liquid crystal retardation layer 21 between the first adhesive layer 31 and the first liquid crystal retardation layer 11.

The optical laminate 4 with the base layer may be obtained by laminating a polarizing plate 50 and a retardation body including a second liquid crystal retardation layer 21 and a first liquid crystal retardation layer 11 via a first adhesive layer 31.

The retardation body can be obtained, for example, by laminating the first liquid crystal retardation layer 13 with a substrate and the second liquid crystal retardation layer 23 with a substrate having the second liquid crystal retardation layer 21 on the second substrate layer 26 (FIG. 4(b)) via the second adhesive layer 32 (FIG. 4(c)). At this time, it is preferable to laminate the first liquid crystal retardation layer 11 side of the first liquid crystal retardation layer 13 with a substrate and the second liquid crystal retardation layer 21 side of the second liquid crystal retardation layer 23 with a substrate via the second adhesive layer 32. When laminating the polarizing plate 50 and the retardation body, it is preferable to laminate them so that the second liquid crystal retardation layer 21 exposed by peeling the second substrate layer 26 from the retardation body is on the polarizing plate 50 side. When peeling the second substrate layer 26 from the retardation body, only the second substrate layer 26 may be peeled off, or the second alignment layer 27 may be peeled off together with the second substrate layer 26. When the retarder shown in FIG. 4(c) includes a second alignment layer 27, the second polymer layer is disposed on the second adhesive layer 32 side, and the second alignment layer 27 is disposed on the opposite side to the second adhesive layer 32 side (the second substrate layer 26 side).

Alternatively, the substrate-layer-attached optical laminate 4 including the second liquid crystal retardation layer 21 may be obtained by the following procedure. First, the polarizing plate 50 and the second liquid crystal retardation layer 21 side of the substrate-attached second liquid crystal retardation layer 23 are laminated via the first adhesive layer 31. Next, the second substrate layer 26 is peeled off, and the exposed second liquid crystal retardation layer 21 and the first liquid crystal retardation layer 11 side of the substrate-attached first liquid crystal retardation layer 13 are laminated via the second adhesive layer 32. At this time, only the second substrate layer 26 may be peeled off, or the second alignment layer 27 may be peeled off together with the second substrate layer 26. As described above, when the substrate-layer-attached optical laminate 4 obtained by sequentially laminating the substrate-attached second liquid crystal retardation layer 23 and the substrate-attached first liquid crystal retardation layer 13 on the polarizing plate 50 includes the second alignment layer 27, the second polymer layer is disposed on the first adhesive layer 31 side, and the second alignment layer is disposed on the first liquid crystal retardation layer 13 side.

In step (S4), the first substrate layer 16 is peeled off from the substrate-attached optical laminates 3 and 4. At this time, only the first substrate layer 16 may be peeled off, or the first substrate layer 16 and the first alignment layer 17 may be peeled off.

The second liquid crystal retardation layer 21 is formed by applying a composition for forming a second liquid crystal retardation layer containing a polymerizable liquid crystal compound onto a second substrate layer 26 or onto a second alignment layer 27 formed on the second substrate layer 26 to obtain a substrate-attached second coating layer 22 having a second substrate layer 26 and a second coating layer 28 (FIG. 4(a));
The method may also include a step of irradiating the substrate-attached second coating layer 22 with active energy rays to polymerize the polymerizable liquid crystal compound in the second coating layer 28 to form a second polymer layer.

The method of irradiating the substrate-attached second coating layer 22 with active energy rays is not particularly limited, and one side of the substrate-attached second coating layer 22 may be irradiated with active energy rays, or both sides may be irradiated with active energy rays. When both sides of the substrate-attached second coating layer 22 are irradiated with active energy rays, it becomes easier to adjust the surface hardness ratio (H21/H22) of the second liquid crystal retardation layer 21 to the above range. The irradiation method and irradiation conditions when irradiating both sides of the substrate-attached second coating layer 22 with active energy rays may be the same as those described in the irradiation method and irradiation conditions of the active energy rays irradiated to the substrate-attached first coating layer 12.

In the above-mentioned method for producing the optical laminate 2, the case where the first liquid crystal retardation layer 13 with the substrate and the second liquid crystal retardation layer 23 with the substrate are laminated to obtain a retardation body has been described, but the method for obtaining a retardation body is not limited to this. For example, the second coating layer may be formed by applying the composition for forming the second liquid crystal retardation layer onto the first liquid crystal retardation layer 11 of the first liquid crystal retardation layer 13 with the substrate, with or without the second alignment layer 27. In this case, the second coating layer formed on the first liquid crystal retardation layer 11 may be irradiated with active energy rays to polymerize the polymerizable liquid crystal compound in the second coating layer to form a second polymer layer. This makes it possible to obtain a retardation body in which the first liquid crystal retardation layer 13 and the second liquid crystal retardation layer 23 are in direct contact with each other.

In the above-mentioned method for producing the optical laminate 2, the case where the optical laminate 4 with the substrate layer has the second liquid crystal retardation layer 21 between the first adhesive layer 31 and the first liquid crystal retardation layer 11 has been described, but the first liquid crystal retardation layer 11 may be between the first adhesive layer 31 and the second liquid crystal retardation layer 21. In this case, for example, in the above-mentioned method for producing the optical laminate 2, the optical laminate 2 can be produced by interchanging the first liquid crystal retardation layer with the substrate and the second liquid crystal retardation layer with the substrate.

Details of the composition for forming the first liquid crystal retardation layer and the composition for forming the second liquid crystal retardation layer, and a more detailed description of the manufacturing method of the first liquid crystal retardation layer and the second liquid crystal retardation layer will be described later.

<Display Device>
The display device includes an optical laminate and an image display element (such as an organic EL display element). The optical laminate is disposed on the viewing side of the image display element. The optical laminate can be attached to the image display element using a pressure-sensitive adhesive layer.

The display device is not particularly limited, and examples include organic electroluminescence (organic EL) display devices, inorganic electroluminescence (inorganic EL) display devices, liquid crystal display devices, electroluminescence display devices, and other display devices.

The display device can be used as mobile devices such as smartphones and tablets, televisions, digital photo frames, electronic signs, measuring instruments, gauges, office equipment, medical equipment, computing equipment, etc.

Hereinafter, details of each layer constituting the optical laminate and a method for producing each layer will be described.
<Retardation Material>
The optical laminate may include a retardation film. The retardation film includes at least one liquid crystal retardation layer that exhibits retardation. The liquid crystal retardation layer includes a polymer layer (first polymer layer or second polymer layer) made of an oriented polymer of a polymerizable liquid crystal compound.

The retarder preferably includes at least a first liquid crystal retardation layer. The retarder may be a laminate of a first liquid crystal retardation layer and a second liquid crystal retardation layer, or may include a liquid crystal retardation layer other than these. The retarder may include a substrate layer (first substrate layer or second substrate layer) used to form the liquid crystal retardation layer.

(First liquid crystal retardation layer, second liquid crystal retardation layer)
The first liquid crystal retardation layer and the second liquid crystal retardation layer are respectively a first polymer layer and a second polymer layer (hereinafter also simply referred to as "polymer layer") containing a polymer of a polymerizable liquid crystal compound. The first liquid crystal retardation layer may be a multilayer of a first polymer layer and a first alignment layer, and the second liquid crystal retardation layer may be a multilayer of a second polymer layer and a second alignment layer. It may be a multi-layer body.

The first liquid crystal retardation layer is obtained by applying a composition for forming a first liquid crystal retardation layer containing a polymerizable liquid crystal compound onto a first base layer or a first alignment layer to form an aligned polymer of the polymerizable liquid crystal compound. The second liquid crystal retardation layer is obtained by applying a composition for forming a second liquid crystal retardation layer containing a polymerizable liquid crystal compound onto a second base layer or a second alignment layer to form an aligned polymer of the polymerizable liquid crystal compound. Forming a liquid crystal retardation layer in this manner is preferable in terms of being able to design a thin film and wavelength dispersion characteristics as desired. The first liquid crystal retardation layer forming composition and the second liquid crystal retardation layer forming composition may each independently further contain a solvent, a photopolymerization initiator, a photosensitizer, an antioxidant, a leveling agent, an adhesion agent, and the like.

The liquid crystal retardation layer is usually a film in which a polymerizable liquid crystal compound is hardened in an oriented state, and in order to generate a retardation in the viewing plane, it usually contains a polymer layer (first polymer layer or second polymer layer) made of a hardened film in which the polymerizable group is polymerized in a state in which the polymerizable liquid crystal compound is oriented horizontally relative to the surface of the substrate layer (first substrate layer or second substrate layer). In this case, if the polymerizable liquid crystal compound is a rod-shaped liquid crystal, a positive A plate is sufficient, and if the polymerizable liquid crystal compound is a disc-shaped liquid crystal, a negative A plate is sufficient.

In order for the optical laminate to achieve a high level of anti-reflection function, the retarder only needs to have a λ/4 plate function (i.e., a π/2 phase difference function) in the entire visible light range. Specifically, it is preferable to have a reverse wavelength dispersion λ/4 layer, or to combine two or more liquid crystal retardation layers with different orientations. For example, it may be a combination of a liquid crystal retardation layer having a λ/2 plate function (i.e., a π phase difference function) and a liquid crystal retardation layer having a λ/4 plate function (i.e., a π/2 phase difference function). Furthermore, from the viewpoint of being able to compensate for the anti-reflection function in an oblique direction, it is preferable to further include a layer having anisotropy in the thickness direction (positive C plate). In addition, each liquid crystal retardation layer may have a tilt orientation or may form a cholesteric orientation state.

When the optical laminate shown in FIG. 1 has an anti-reflection function and functions as a circular polarizer, the first liquid crystal retardation layer is preferably a λ/4 liquid crystal retardation layer that provides a phase difference of λ/4. When the optical laminate shown in FIG. 2 has an anti-reflection function and functions as a circular polarizer, [i] the first liquid crystal retardation layer may be a λ/4 liquid crystal retardation layer and the second liquid crystal retardation layer may be a λ/2 liquid crystal retardation layer that provides a phase difference of λ/2, or [ii] the first liquid crystal retardation layer may be a positive C plate and the second liquid crystal retardation layer may be a λ/4 liquid crystal retardation layer.

The λ/4 function over the entire visible light range preferably satisfies the optical characteristics shown in the following formula (1), where R(λ) is the in-plane retardation for light with a wavelength of λ nm, and more preferably satisfies the optical characteristics shown in the following formulas (1), (2), and (3).
100nm<Re(550)<160nm (1)
Re(450)/Re(550)≦1.0 (2)
1.00≦Re(650)/Re(550) (3)
[In formulas (1) to (3),
Re(450) represents the in-plane phase difference value (in-plane retardation) for light having a wavelength of 450 nm,
Re(550) represents an in-plane retardation value for light having a wavelength of 550 nm;
Re(650) represents an in-plane retardation value for light having a wavelength of 650 nm.]

When the "Re(450)/Re(550)" of the retardation film exceeds 1.0, the light leakage on the short wavelength side of the elliptical polarizing plate equipped with the retardation film increases. The value of "Re(450)/Re(550)" is preferably 0.7 or more and 1.0 or less, more preferably 0.80 or more and 0.95 or less, even more preferably 0.80 or more and 0.92 or less, and particularly preferably 0.82 or more and 0.88 or less. The value of "Re(450)/Re(550)" can be adjusted arbitrarily by adjusting the mixing ratio of the polymerizable liquid crystal compound, the stacking angle of the multiple liquid crystal retardation layers, and the retardation value.

The in-plane retardation value of the liquid crystal retardation layer can be adjusted by the thickness of the liquid crystal retardation layer. Since the in-plane retardation value is determined by the following formula (4), in order to obtain a desired in-plane retardation value (Re(λ)), Δn(λ) and the film thickness d may be adjusted. The thickness of the liquid crystal retardation layer is usually 10 μm or less, preferably 0.3 μm or more and 5 μm or less, more preferably 0.5 μm or more and 5 μm or less, and even more preferably 1 μm or more and 3 μm or less. The thickness of the liquid crystal retardation layer can be measured by an interference film thickness meter, a laser microscope, or a stylus film thickness meter. Δn(λ) in formula (4) depends on the molecular structure of the polymerizable liquid crystal compound described later.
Re(λ)=d×Δn(λ) (4)
[In the formula, Re(λ) represents an in-plane retardation value at a wavelength of λ nm, d represents a film thickness, and Δn(λ) represents a birefringence at a wavelength of λ nm.]

As one method for achieving anti-reflection performance, a configuration in which a layer having a positive wavelength dispersion λ/2 layer and a layer having a positive wavelength dispersion λ/4 layer are combined is known. For example, this can be obtained by combining a layer having optical properties represented by formulas (5), (7), and (8) with a layer having optical properties represented by formulas (6), (7), and (8) in a specific slow axis relationship.
100nm<Re(550)<160nm (5)
200nm<Re(550)<320nm (6)
Re(450)/Re(550)≧1.00 (7)
1.00≧Re(650)/Re(550) (8)
[In formulas (5) to (8),
Re(450) represents an in-plane retardation value for light having a wavelength of 450 nm;
Re(550) represents an in-plane retardation value for light having a wavelength of 550 nm;
Re(650) represents an in-plane retardation value for light with a wavelength of 650 nm.]

Methods for combining the above layers include well-known methods such as those described in JP 2015-163935 A and WO 2013/137464. From the viewpoint of viewing angle compensation, it is preferable to use a λ/2 liquid crystal retardation layer containing a polymer of a disc-shaped polymerizable liquid crystal compound and a λ/4 liquid crystal retardation layer containing a polymer of a rod-shaped polymerizable liquid crystal compound. The in-plane retardation value can be measured using KOBRA-WR manufactured by Oji Scientific Instruments Co., Ltd.

It is preferable that the laminate (retardation film) of the first liquid crystal retardation layer 11 and the second liquid crystal retardation layer 21 satisfies the relationship of the following formulas (1)' and (2)'.
100≦Re(550)≦180 (1)'
Re(450)/Re(550)≦1.00 (2)'
[In formula (1)′ and formula (2)′,
Re(450) represents an in-plane retardation value for light having a wavelength of 450 nm;
Re(550) represents an in-plane retardation value for light having a wavelength of 550 nm.]
The in-plane retardation value of the laminate (retardation film) of the first liquid crystal retardation layer 11 and the second liquid crystal retardation layer 21 is a value measured using KOBRA-WR manufactured by Oji Scientific Instruments Co., Ltd. in a state where the laminate is laminated with the polarizing plate 50.

An example of a disc-shaped polymerizable liquid crystal compound is a compound containing a group represented by formula (W) (hereinafter, sometimes referred to as a polymerizable liquid crystal compound).

［式（Ｗ）中、Ｒ^４０は、下記式（Ｗ－１）～（Ｗ－５）を表す。

［式（Ｗ－１）～（Ｗ－５）中、
Ｘ^４０及びＺ^４０は、炭素数１～１２のアルカンジイル基を表し、該アルカンジイル基に含まれる水素原子は、炭素数１～５のアルコキシ基で置換されていてもよく、該アルコキシ基に含まれる水素原子は、ハロゲン原子で置換されていてもよい。また、該アルカンジイル基を構成する－ＣＨ_２－は、－Ｏ－又は－ＣＯ－に置き換わっていてもよい。
ｍ２は、整数を表す。］］

In formula (W), R ⁴⁰ represents any one of the following formulae (W-1) to (W-5).

[In formulas (W-1) to (W-5),
X ⁴⁰ and Z ⁴⁰ each represent an alkanediyl group having 1 to 12 carbon atoms, and a hydrogen atom contained in the alkanediyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, and a hydrogen atom contained in the alkoxy group may be substituted with a halogen atom. In addition, -CH ₂ - constituting the alkanediyl group may be replaced with -O- or -CO-.
m2 represents an integer.

Examples of the rod-shaped polymerizable liquid crystal compound include compounds represented by formula (I), formula (II), formula (III), formula (IV), formula (V), and formula (VI).
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-B16-E12-B17-P12 (I)
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-A14-F11 (II)
P11-B11-E11-B12-A11-B13-A12-B14-A13-B15-E12-B17-P12 (III)
P11-B11-E11-B12-A11-B13-A12-B14-A13-F11 (IV)
P11-B11-E11-B12-A11-B13-A12-B14-E12-B17-P12 (V)
P11-B11-E11-B12-A11-B13-A12-F11 (VI)
[In formulas (I) to (VI),
A11 to A14 each independently represent a divalent alicyclic hydrocarbon group or a divalent aromatic hydrocarbon group. A hydrogen atom contained in the divalent alicyclic hydrocarbon group and the divalent aromatic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group, or a nitro group, and a hydrogen atom contained in the alkyl group having 1 to 6 carbon atoms and the alkoxy group having 1 to 6 carbon atoms may be substituted with a fluorine atom.
B11 and B17 each independently represent -O-, -S-, -CO-O-, -O-CO-, -O-CO-O-, -CO-NR ¹⁶ -, -NR ¹⁶ -CO-, -CO-, -CS-, or a single bond, and R ¹⁶ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.
B12 to B16 each independently represent -C≡C-, -CH=CH-, -CH ₂ -CH ₂ -, -O-, -S-, -C(=O)-, -C(=O)-O-, -O-C(=O)-, -O-C(=O)-O-, -CH=N-, -N=CH-, -N=N-, -C(=O)-NR ¹⁶ -, -NR ¹⁶ -C(=O)-, -OCH ₂ -, -OCF ₂ -, -CH ₂ O-, -CF ₂ O-, -CH=CH-C(=O)-O-, -O-C(=O)-CH=CH- or a single bond.
E11 and E12 each independently represent an alkanediyl group having 1 to 12 carbon atoms, a hydrogen atom contained in the alkanediyl group may be substituted with an alkoxy group having 1 to 5 carbon atoms, a hydrogen atom contained in the alkoxy group may be substituted with a halogen atom, and -CH ₂ - constituting the alkanediyl group may be replaced with -O- or -CO-.
F11 represents a hydrogen atom, an alkyl group having 1 to 13 carbon atoms, an alkoxy group having 1 to 13 carbon atoms, a cyano group, a nitro group, a trifluoromethyl group, a dimethylamino group, a hydroxy group, a methylol group, a formyl group, a sulfo group (—SO ₃ H), a carboxy group, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom, and —CH ₂ — constituting the alkyl group and the alkoxy group may be replaced by —O—.
P11 and P12 each independently represent a polymerizable group.

In addition to the above-mentioned configuration combining a positive wavelength dispersion λ/2 layer and a positive wavelength dispersion λ/4 layer, configurations with tilt alignment or cholesteric alignment can also be used without any particular restrictions as long as they achieve anti-reflection function. Examples of such configurations include those described in WO2021/060378, WO2021/132616, WO2021/132624, etc.

The positive C plate is not particularly limited as long as it has anisotropy in the thickness direction, but if it does not have tilt alignment or cholesteric alignment, it has optical characteristics represented by the following formula (9).
nx≒ny<nz (9)
[In formula (9),
nx represents the principal refractive index at a wavelength λ [nm] in the plane of the positive C plate.
ny represents the refractive index of the positive C plate at a wavelength λ [nm] in a direction perpendicular to nx in the same plane as nx.
nz(λ) represents the refractive index at a wavelength λ [nm] in the thickness direction of the positive C plate.
If nx≈ny, nx can be the refractive index in any direction in the plane of the positive C-plate.

The in-plane retardation value Re(550) of the positive C plate at a wavelength of 550 nm is usually in the range of 0 nm to 10 nm, and preferably in the range of 0 nm to 5 nm. The retardation value Rth(550) in the thickness direction at a wavelength of 550 nm is usually in the range of -170 nm to -10 nm, and preferably in the range of -150 nm to -20 nm, and more preferably in the range of -100 nm to -40 nm. If the retardation value in the thickness direction is in this range, the anti-reflection properties from oblique directions can be further improved.

When the positive C plate is a liquid crystal retardation layer, its thickness is usually 10 μm or less, preferably 5 μm or less, and more preferably 0.3 μm or more and 3 μm or less.

The positive C plate is preferably a liquid crystal retardation layer. More preferably, it is a rod-shaped polymerizable liquid crystal compound. Examples of rod-shaped polymerizable liquid crystal compounds include the compounds represented by the above formulas (I) to (VI).

(Polymerizable Liquid Crystal Compound Constituting Liquid Crystal Retardation Layer)
The polymerizable liquid crystal compound contained in the first liquid crystal retardation layer forming composition and the second liquid crystal retardation layer forming composition (hereinafter also referred to as "liquid crystal retardation layer forming composition") means a liquid crystal compound having a polymerizable group, particularly a photopolymerizable group, and as the polymerizable liquid crystal compound, a conventionally known polymerizable liquid crystal compound can be used. The photopolymerizable group refers to a group that can be involved in a polymerization reaction by a reactive species generated from a photopolymerization initiator, such as an active radical or an acid. Examples of the photopolymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred. The polymerizable liquid crystal compound may be a thermotropic liquid crystal or a lyotropic liquid crystal, but a thermotropic liquid crystal is preferred in terms of the ability to precisely control the film thickness. The phase ordered structure of the thermotropic liquid crystal may be nematic or smectic. The polymerizable liquid crystal compound may be rod-shaped or discotic. The polymerizable liquid crystal compound may be used alone or in combination of two or more kinds.

As the polymerizable liquid crystal compound, from the viewpoint of expressing reverse wavelength dispersion, liquid crystals having a T-shaped or H-shaped mesogen structure that has additional birefringence in the direction perpendicular to the molecular long axis direction are preferred, and from the viewpoint of obtaining stronger dispersion, T-shaped liquid crystals are more preferred. Specific examples of the T-shaped liquid crystal structure include compounds represented by the following formula (VII).

［式（ＶＩＩ）中、
Ａｒは置換基を有していてもよい二価の芳香族基を表す。該二価の芳香族基中には窒素原子、酸素原子、硫黄原子のうち少なくとも１つ以上が含まれることが好ましい。二価の基Ａｒに含まれる芳香族基が２つ以上である場合、２つ以上の芳香族基は互いに単結合、－ＣＯ－Ｏ－、－Ｏ－等の二価の結合基で結合していてもよい。
Ｇ^１及びＧ^２はそれぞれ独立に、二価の芳香族基又は二価の脂環式炭化水素基を表す。ここで、該二価の芳香族基又は二価の脂環式炭化水素基に含まれる水素原子は、ハロゲン原子、炭素数１～４のアルキル基、炭素数１～４のフルオロアルキル基、炭素数１～４のアルコキシ基、シアノ基又はニトロ基に置換されていてもよく、該二価の芳香族基又は二価の脂環式炭化水素基を構成する炭素原子が、酸素原子、硫黄原子又は窒素原子に置換されていてもよい。
Ｌ^１、Ｌ^２、Ｂ^１及びＢ^２はそれぞれ独立に、単結合又は二価の連結基である。
ｋ、ｌは、それぞれ独立に０～３の整数を表し、１≦ｋ＋ｌの関係を満たす。ここで、２≦ｋ＋ｌである場合、Ｂ^１及びＢ^２、Ｇ^１及びＧ^２は、それぞれ互いに同一であってもよく、異なっていてもよい。
Ｅ^１及びＥ^２はそれぞれ独立に、炭素数１～１７のアルカンジイル基を表し、ここで、アルカンジイル基に含まれる水素原子は、ハロゲン原子で置換されていてもよく、該アルカンジイル基に含まれる－ＣＨ_２－は、－Ｏ－、－Ｓ－、－ＣＯＯ－で置換されていてもよく、－Ｏ－、－Ｓ－、－ＣＯＯ－を複数有する場合は互いに隣接しない。
Ｐ^１及びＰ^２は互いに独立に、重合性基又は水素原子を表し、少なくとも１つは重合性基である。］

[In the formula (VII),
Ar represents a divalent aromatic group which may have a substituent. The divalent aromatic group preferably contains at least one of a nitrogen atom, an oxygen atom, and a sulfur atom. When the divalent group Ar contains two or more aromatic groups, the two or more aromatic groups may be bonded to each other via a divalent bonding group such as a single bond, -CO-O-, or -O-.
G ¹ and G ² each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and a carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom.
L ¹ , L ² , B ¹ and B ² each independently represent a single bond or a divalent linking group.
k and l each independently represent an integer of 0 to 3, and satisfy the relationship of 1≦k+l, where, when 2≦k+l, B ¹ and B ² , G ¹ and G ² may be the same as or different from each other.
^E1 and ^E2 each independently represent an alkanediyl group having 1 to 17 carbon atoms, in which a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and _-CH2- contained in the alkanediyl group may be substituted with -O-, -S- or -COO-, and when there are a plurality of -O-, -S- or -COO-, they are not adjacent to each other.
P ¹ and P ² each independently represent a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

G ¹ and G ² are each independently preferably a 1,4-phenylenediyl group which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, or a 1,4-cyclohexanediyl group which may be substituted with at least one substituent selected from the group consisting of a halogen atom and an alkyl group having 1 to 4 carbon atoms, more preferably a 1,4-phenylenediyl group substituted with a methyl group, an unsubstituted 1,4-phenylenediyl group, or an unsubstituted 1,4-trans-cyclohexanediyl group, and particularly preferably an unsubstituted 1,4-phenylenediyl group, or an unsubstituted 1,4-trans-cyclohexanediyl group.
At least one of a plurality of ^G1 and ^G2 is preferably a divalent alicyclic hydrocarbon group, and more preferably at least one of ^G1 and ^G2 bonded to ^L1 or ^L2 is a divalent alicyclic hydrocarbon group.

L ¹ and L ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a1 OR ^a2 -, -R ^a3 COOR ^a4 -, -R ^a5 OCOR ^a6 -, R ^a7 OC═OOR ^a8 -, -N═N-, -CR ^c ═CR ^d -, or -C≡C-, where R ^a1 to R ^a8 are each independently a single bond or an alkylene group having 1 to 4 carbon atoms, and R ^c and R ^d are an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. L ¹ and L ² are each independently more preferably a single bond, -OR ^a2-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a4-1 -, or OCOR ^a6-1 -. Here, R ^a2-1 , R ^a4-1 , and R ^a6-1 each independently represent a single bond, -CH ₂ -, or -CH ₂ CH ₂ -. L ¹ and L ² are each independently more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, or -OCO-.

B ¹ and B ² are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R ^a9 OR ^a10 -, -R ^a11 COOR ^a12 -, -R ^a13 OCOR ^a14 -, or -R ^a15 OC═OOR ^a16 -. Here, R ^a9 to R ^a16 are each independently a single bond, or an alkylene group having 1 to 4 carbon atoms. B ¹ and B ² are each independently more preferably a single bond, -OR ^a10-1 -, -CH ₂ -, -CH ₂ CH ₂ -, -COOR ^a12-1 -, or -OCOR ^a14-1 -. Here, R ^a10-1 , R ^a12-1 and R ^a14-1 each independently represent a single bond, -CH ₂ - or -CH ₂ CH ₂ -. B ¹ and B ² each independently represent more preferably a single bond, -O-, -CH ₂ CH ₂ -, -COO-, -COOCH ₂ CH ₂ -, -OCO- or -OCOCH ₂ CH ₂ -.

From the viewpoint of expressing reverse wavelength dispersion, k and l are preferably in the range of 2≦k+l≦6, preferably k+l=4, and more preferably k=2 and l=2. k=2 and l=2 are preferable because they result in a symmetrical structure.

E ¹ and E ² each independently preferably represent an alkanediyl group having 1 to 17 carbon atoms, and more preferably an alkanediyl group having 4 to 12 carbon atoms.

Examples of the polymerizable group represented by ^P1 or ^P2 include an epoxy group, a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among these, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and an acryloyloxy group is more preferred.

It is preferable that Ar has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocycle which may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring, and a benzene ring and a naphthalene ring are preferable. Examples of the aromatic heterocycle include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. Among them, it is preferable that Ar has a thiazole ring, a benzothiazole ring, or a benzofuran ring, and it is more preferable that Ar has a benzothiazole group. In addition, when Ar contains a nitrogen atom, it is preferable that the nitrogen atom has π electrons.

In formula (VII), the total number Nπ of π electrons contained in the divalent aromatic group represented by _Ar is preferably 8 or more, more preferably 10 or more, even more preferably 14 or more, and particularly preferably 16 or more. Also, it is preferably 30 or less, more preferably 26 or less, and even more preferably 24 or less.

Suitable examples of the aromatic group represented by Ar include the following groups.

In formulas (Ar-1) to (Ar-23),
The * marks indicate connecting parts.
Z ⁰ , Z ¹ and Z ² each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N,N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 12 carbon atoms, or an N,N-dialkylsulfamoyl group having 2 to 12 carbon atoms.
Q ¹ and Q ² each independently represent -CR ^{2 '} R ^{3 '} -, -S-, -NH-, -NR ^{2 '} -, -CO- or O-; R ^{2 '} and R ^{3 '} each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
J ¹ and J ² each independently represent a carbon atom or a nitrogen atom.
Y ¹ , Y ² and Y ³ each independently represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may be substituted.
W ¹ and W ² each independently represent a hydrogen atom, a cyano group, a methyl group or a halogen atom.
m represents an integer of 0 to 6.

Examples of the aromatic hydrocarbon group in ^Y1 , ^Y2 , and ^Y3 include aromatic hydrocarbon groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group, of which a phenyl group and a naphthyl group are preferred, and a phenyl group is more preferred. Examples of the aromatic heterocyclic group include aromatic heterocyclic groups having 4 to 20 carbon atoms and containing at least one heteroatom, such as a nitrogen atom, an oxygen atom, or a sulfur atom, such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group, of which a furyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group are preferred.

^Y1 , ^Y2 and ^Y3 may each independently be an optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a condensed polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group refers to a condensed polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

Z ⁰ , Z ¹ and Z ² are each preferably independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, or an alkoxy group having 1 to 12 carbon atoms, Z ⁰ is more preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a cyano group, and Z ¹ and Z ² are more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a cyano group.

^Q1 and ^Q2 are each preferably independently -NH-, -S-, ^-NR2'- or -O-, and R2 ^' is preferably a hydrogen atom. Among these, -S-, -O- or -NH- is particularly preferred.

Among formulas (Ar-1) to (Ar-23), formulas (Ar-6) and (Ar-7) are preferred from the viewpoint of molecular stability.

In formulae (Ar-16) to (Ar-23), Y ¹ may form an aromatic heterocyclic group together with the nitrogen atom to which it is bonded and Z ^0. Examples of the aromatic heterocyclic group include those described above as aromatic heterocyclic rings that Ar may have, such as a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an indole ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pyrrolidine ring. This aromatic heterocyclic group may have a substituent. In addition, Y ¹ may be, together with the nitrogen atom to which it is bonded and Z ⁰ , the aforementioned polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group which may be substituted. Examples include a benzofuran ring, a benzothiazole ring, and a benzoxazole ring.

Among the polymerizable liquid crystal compounds, compounds having a maximum absorption wavelength of 300 to 400 nm are preferred. When a photopolymerization initiator is contained in the liquid crystal retardation layer forming composition, the polymerization reaction and gelation of the polymerizable liquid crystal compound may progress during long-term storage. However, if the maximum absorption wavelength of the polymerizable liquid crystal compound is 300 to 400 nm, even if it is exposed to ultraviolet light during storage, the generation of reactive species from the photopolymerization initiator and the polymerization reaction and gelation of the polymerizable liquid crystal compound caused by the reactive species can be effectively suppressed. Therefore, it is advantageous in terms of the long-term stability of the polymerizable liquid crystal composition, and the orientation and uniformity of the film thickness of the obtained polymer layer (liquid crystal cured film) can be improved. The maximum absorption wavelength of the polymerizable liquid crystal compound can be measured using a UV-visible spectrophotometer in a solvent. The solvent is a solvent that can dissolve the polymerizable liquid crystal compound, and examples of the solvent include chloroform.

The content of the polymerizable liquid crystal compound in the liquid crystal retardation layer forming composition is, for example, 70 to 99.5 parts by mass, preferably 80 to 99 parts by mass, more preferably 85 to 98 parts by mass, and even more preferably 90 to 95 parts by mass, based on 100 parts by mass of the solid content of the liquid crystal retardation layer forming composition. If the content of the polymerizable liquid crystal compound is within the above range, it is advantageous from the viewpoint of the orientation of the resulting polymer layer (liquid crystal cured film). In this specification, the solid content of the liquid crystal retardation layer forming composition means all components excluding volatile components such as organic solvents from the liquid crystal retardation layer forming composition.

The liquid crystal retardation layer forming composition may further contain reactive additives such as a solvent, a leveling agent, a polymerization initiator, a photosensitizer, an antioxidant, a crosslinking agent, and an adhesion agent, and it is preferable that the composition contains a solvent or a leveling agent from the viewpoint of processability.

The liquid crystal retardation layer forming composition may contain a solvent. Since polymerizable liquid crystal compounds generally have high viscosity, dissolving the liquid crystal retardation layer forming composition in a solvent often facilitates application, and as a result, the liquid crystal retardation layer is often easily formed. The solvent is preferably one that can completely dissolve the polymerizable liquid crystal compound, and is preferably a solvent that is inactive to the polymerization reaction of the polymerizable liquid crystal compound.

Examples of the solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone or propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene, and nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; and amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone. These solvents may be used alone or in combination of two or more.

The content of the solvent is preferably 50 to 98% by mass relative to the total amount of the composition for forming the liquid crystal retardation layer. In other words, the content of the solid content in the composition for forming the liquid crystal retardation layer is preferably 2 to 50% by mass, more preferably 5 to 30% by mass. If the content of the solid content is 50% by mass or less, the viscosity of the composition for forming the liquid crystal retardation layer is low, and the thickness of the liquid crystal retardation layer becomes approximately uniform, so that the liquid crystal retardation layer tends to be less prone to unevenness. In addition, the content of the solid content can be determined in consideration of the thickness of the liquid crystal retardation layer to be manufactured.

The liquid crystal retardation layer forming composition may contain a leveling agent. The leveling agent is an additive that adjusts the fluidity of the liquid crystal retardation layer forming composition and makes the film obtained by applying the liquid crystal retardation layer forming composition flatter. Examples of the leveling agent include organic modified silicone-based, polyacrylate-based and perfluoroalkyl-based leveling agents. Among them, when horizontal alignment is performed, polyacrylate-based and perfluoroalkyl-based leveling agents are preferred, and when vertical alignment is performed, organic modified silicone-based and perfluoroalkyl-based leveling agents are preferred.

When the liquid crystal retardation layer forming composition contains a leveling agent, the leveling agent is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, the polymerizable liquid crystal compound is easily aligned horizontally, and the obtained liquid crystal retardation layer tends to be smoother. When the content of the leveling agent relative to the polymerizable liquid crystal compound exceeds the above range, the obtained liquid crystal retardation layer tends to be uneven. The liquid crystal retardation layer forming composition may contain two or more types of leveling agents.

The liquid crystal retardation layer forming composition may contain a polymerization initiator. The polymerization initiator is a compound that can initiate a polymerization reaction of a polymerizable liquid crystal compound or the like. As the polymerization initiator, a photopolymerization initiator that generates active radicals by the action of light is preferable from the viewpoint of not depending on the phase state of the thermotropic liquid crystal.

The photopolymerization initiator may be any known photopolymerization initiator, so long as it is a compound capable of initiating the polymerization reaction of the polymerizable liquid crystal compound. Specific examples include photopolymerization initiators capable of generating active radicals or acids under the action of light, and among these, photopolymerization initiators that generate radicals under the action of light are preferred. The photopolymerization initiators may be used alone or in combination of two or more kinds.

As the photopolymerization initiator, a known photopolymerization initiator can be used. For example, as a photopolymerization initiator that generates active radicals, self-cleavage type benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, azo compounds, etc. can be used, and hydrogen abstraction type benzophenone compounds, alkylphenone compounds, benzoin ether compounds, benzyl ketal compounds, dibenzosuberone compounds, anthraquinone compounds, xanthone compounds, thioxanthone compounds, halogenoacetophenone compounds, dialkoxyacetophenone compounds, halogenobisimidazole compounds, halogenotriazine compounds, triazine compounds, etc. can be used. As a photopolymerization initiator that generates acid, iodonium salts and sulfonium salts can be used. From the viewpoint of excellent reaction efficiency at low temperatures, self-cleavage type photopolymerization initiators are preferred, and acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, and oxime ester compounds are particularly preferred.

The content of the polymerization initiator in the liquid crystal retardation layer forming composition can be adjusted appropriately depending on the type and amount of the polymerizable liquid crystal compound, but is usually 0.1 to 30 parts by mass, preferably 0.5 to 10 parts by mass, and more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the polymerization initiator is within the above range, polymerization can be performed without disturbing the alignment of the polymerizable liquid crystal compound.

The liquid crystal retardation layer forming composition may contain a sensitizer. The sensitizer is preferably a photosensitizer. Examples of the sensitizer include xanthone compounds such as xanthone and thioxanthone (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.); anthracene compounds such as anthracene and alkoxy group-containing anthracene (e.g., dibutoxyanthracene, etc.); phenothiazine, rubrene, etc.

When the liquid crystal retardation layer forming composition contains a sensitizer, the polymerization reaction of the polymerizable liquid crystal compound contained in the liquid crystal retardation layer forming composition can be further promoted. The amount of such a sensitizer used is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound.

In order to ensure stable progress of the polymerization reaction, the liquid crystal retardation layer may contain an antioxidant. The antioxidant can control the degree of progress of the polymerization reaction of the polymerizable liquid crystal compound.

The antioxidant may be, for example, a primary antioxidant selected from a phenol-based antioxidant, an amine-based antioxidant, a quinone-based antioxidant, or a nitroso-based antioxidant, or a secondary antioxidant selected from a phosphorus-based antioxidant and a sulfur-based antioxidant.

When the liquid crystal retardation layer forming composition contains an antioxidant, the content of the antioxidant is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and even more preferably 0.5 to 8 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. The antioxidants can be used alone or in combination of two or more kinds. When the content of the antioxidant is within the above range, polymerization can be performed without disturbing the alignment of the polymerizable liquid crystal compound.

The liquid crystal retardation layer forming composition may contain a reactive additive. The reactive additive preferably has a carbon-carbon unsaturated bond, an active hydrogen reactive group, or a thiol group in its molecule. The "active hydrogen reactive group" here means a group that is reactive to a group having active hydrogen such as a carboxyl group (-COOH), a hydroxyl group (-OH), or an amino group (-NH ₂ ), and representative examples thereof include a glycidyl group, an oxazoline group, a carbodiimide group, an aziridine group, an imide group, an isocyanate group, a thioisocyanate group, and a maleic anhydride group. The number of reactive groups possessed by the reactive additive is usually 1 to 20, and preferably 1 to 10.

(Method of manufacturing liquid crystal retardation layer)
The liquid crystal retardation layer can be produced by applying a liquid crystal retardation layer-forming composition (a first liquid crystal retardation layer-forming composition or a second liquid crystal retardation layer-forming composition) onto a substrate layer (a first substrate layer or a second substrate layer) or onto an alignment layer (a first alignment layer or a second alignment layer) formed on the substrate layer.

Methods for applying the liquid crystal retardation layer forming composition onto the substrate layer or the alignment layer include extrusion coating, direct gravure coating, reverse gravure coating, CAP coating, slit coating, microgravure, die coating, inkjet, etc. Also included are methods of applying using a coater such as a dip coater, bar coater, or spin coater. Among these, when applying continuously in a roll-to-roll format, the application methods of the microgravure method, inkjet method, slit coating method, and die coating method are preferred, and when applying to a sheet substrate such as glass, the highly uniform spin coating method is preferred. When applying in a roll-to-roll format, an alignment layer can be formed by applying the alignment layer forming composition to the substrate layer, and the liquid crystal retardation layer forming composition can be continuously applied onto the resulting alignment layer.

Drying methods for removing the solvent contained in the liquid crystal retardation layer forming composition include, for example, natural drying, ventilation drying, heat drying, reduced pressure drying, and combinations of these. Of these, natural drying or heat drying is preferred. The drying temperature is preferably in the range of 0 to 200°C, more preferably in the range of 20 to 150°C, and even more preferably in the range of 50 to 130°C. The drying time is preferably 10 seconds to 10 minutes, and more preferably 30 seconds to 5 minutes. The alignment layer forming composition can also be dried in the same manner.

Photopolymerization is preferred as a method for polymerizing the polymerizable liquid crystal compound contained in the liquid crystal retardation layer forming composition. Photopolymerization is performed by irradiating an active energy ray to a laminate in which a liquid crystal retardation layer forming composition containing a polymerizable liquid crystal compound is applied on a substrate layer or an alignment layer. The active energy ray to be irradiated is appropriately selected according to the type of polymerizable liquid crystal compound contained in the dried coating (particularly, the type of photopolymerizable functional group possessed by the polymerizable liquid crystal compound), the type of photopolymerization initiator when a photopolymerization initiator is contained, and the amount thereof. Specifically, one or more types of active energy rays selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α rays, β rays, and γ rays can be mentioned. Among them, ultraviolet light is preferred in that the progress of the polymerization reaction is easily controlled and that photopolymerization devices widely used in this field can be used, and it is preferable to select the type of polymerizable liquid crystal compound so that it can be photopolymerized by ultraviolet light.

Examples of light sources for active energy rays include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources emitting light in the wavelength range of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

The ultraviolet irradiation intensity is usually 10 mW/cm ² or more and 3,000 mW/cm ² or less. The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating a cationic polymerization initiator or a radical polymerization initiator. The time for irradiating ultraviolet light is usually 0.1 seconds or more and 10 minutes or less, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and even more preferably 10 seconds or more and 1 minute or less. When irradiating once or multiple times with such ultraviolet irradiation intensity, the accumulated light amount is usually 10 mJ/cm ² or more and 3,000 mJ/cm ² or less, preferably 50 mJ/cm ² or more and 2,000 mJ/cm ² or less, and more preferably 100 mJ/cm ² or more and 1,000 mJ/cm ² or less. When the accumulated light amount is below this range, the polymerizable liquid crystal compound may not be cured sufficiently and good transferability may not be obtained. On the other hand, if the integrated light amount is greater than this range, the optical film including the liquid crystal retardation layer may be colored.

(Base material layer (first base material layer, second base material layer))
The substrate layer (the first substrate layer or the second substrate layer) supports the liquid crystal retardation layer (the first liquid crystal retardation layer or the second liquid crystal retardation layer). The substrate layer may be a glass substrate or a film substrate, preferably a film substrate, and more preferably a long rolled film in terms of being capable of being produced continuously. The material layer is preferably a transparent substrate layer. Examples of the resin constituting the film substrate include polyolefins such as polyethylene, polypropylene, and norbornene-based polymers; cyclic olefin-based resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic Plastics such as acid esters, polyacrylic acid esters, cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate, polyethylene naphthalate, polycarbonate, polysulfone, polyethersulfone, polyetherketone, polyphenylene sulfide, and polyphenylene oxide. Examples include: Among these, from the viewpoint of transparency when used in optical film applications, a film substrate made of a resin selected from the group consisting of triacetyl cellulose, cyclic olefin resin, polymethacrylic acid ester, and polyethylene terephthalate is more preferred.

Examples of commercially available cellulose ester substrates include "FUJITAC FILM" (manufactured by Fuji Photo Film Co., Ltd.); "KC8UX2M", "KC8UY" and "KC4UY" (all manufactured by Konica Minolta Opto, Inc.).
Commercially available cyclic olefin resins include "Topas" (registered trademark) (manufactured by Ticona (Germany)), "Arton" (registered trademark) (manufactured by JSR Corporation), "ZEONOR" (registered trademark), "ZEONEX" (registered trademark) (all manufactured by Zeon Corporation), and "Apel" (registered trademark) (manufactured by Mitsui Chemicals, Inc.). Such cyclic olefin resins can be formed into a film by known means such as a solvent casting method or a melt extrusion method to form a substrate.
Commercially available cyclic olefin resin substrates can also be used. Commercially available cyclic olefin resin substrates include "S-Cina" (registered trademark), "SCA40" (registered trademark) (both manufactured by Sekisui Chemical Co., Ltd.), "ZEONOR FILM" (registered trademark) (manufactured by Optes Co., Ltd.), and "ARTON FILM" (registered trademark) (manufactured by JSR Corporation).

The thickness of the substrate layer is preferably thin enough to allow practical handling, but if it is too thin, the strength decreases and the processability tends to be poor. The thickness of the substrate layer is usually 5 μm to 300 μm, preferably 10 μm to 200 μm, and more preferably 10 μm to 50 μm. In addition, a further thinning effect can be obtained by peeling off the substrate layer and transferring the liquid crystal retardation layer.

In producing an optical laminate, the coating layer of the liquid crystal retardation layer forming composition may be irradiated with active energy rays such as ultraviolet rays through the substrate layer. When the active energy rays are ultraviolet rays, it is preferable that the substrate layer has good ultraviolet transmittance so that the ultraviolet rays can reach the coating layer efficiently. Specifically, the light transmittance of the substrate layer at a wavelength of 340 nm is preferably 10% or more, more preferably 20% or more, and even more preferably 30% or more. The light transmittance of the substrate layer can be measured using a UV-visible spectrophotometer.

(Alignment Layer (First Alignment Layer, Second Alignment Layer))
The alignment layer has an alignment regulating force for aligning the polymerizable liquid crystal compound in a desired direction.

The alignment layer facilitates the alignment of the polymerizable liquid crystal compound. The state of liquid crystal alignment, such as horizontal alignment, vertical alignment, hybrid alignment, and tilt alignment, varies depending on the properties of the alignment layer and the polymerizable liquid crystal compound, and the combination can be selected arbitrarily. For example, if the alignment film is a material that exerts horizontal alignment as an alignment control force, the polymerizable liquid crystal compound can form a horizontal alignment or a hybrid alignment, and if the alignment film is a material that exerts vertical alignment, the polymerizable liquid crystal compound can form a vertical alignment or a tilt alignment. The expressions horizontal, vertical, and the like refer to the direction of the optical axis of the aligned polymerizable liquid crystal compound when the liquid crystal retardation layer plane is used as a reference. For example, vertical alignment means that the optical axis of the aligned polymerizable liquid crystal compound is in a direction perpendicular to the liquid crystal retardation layer plane. The term "vertical" here means 90°±20° relative to the liquid crystal retardation layer plane.

When the alignment layer is made of an alignment polymer, the alignment control force can be adjusted as desired by changing the surface condition and rubbing conditions. When the alignment layer is made of a photoalignment polymer, the alignment control force can be adjusted as desired by changing the polarized light irradiation conditions, etc. In addition, the liquid crystal alignment can be controlled by selecting the physical properties of the polymerizable liquid crystal compound, such as the surface tension and liquid crystallinity.

The alignment layer formed between the base layer and the liquid crystal retardation layer is preferably insoluble in the solvent used to form the liquid crystal retardation layer on the alignment layer, and is heat resistant to the heat treatment for removing the solvent and for aligning the liquid crystal. Examples of the alignment layer include an alignment layer made of an orienting polymer, a photoalignment layer, a groove alignment film, and a stretched film stretched in the alignment direction. When applied to a long rolled film, a photoalignment layer is preferred because the alignment direction can be easily controlled.

The thickness of the alignment layer is usually in the range of 10 nm to 5000 nm, preferably in the range of 10 nm to 1000 nm, and more preferably in the range of 30 to 300 nm.

Examples of the alignment polymers used in the rubbing alignment layer include polyamides and gelatins having amide bonds in the molecule, polyimides having imide bonds in the molecule, and their hydrolyzates such as polyamic acid, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazole, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylic acid esters. Among these, polyvinyl alcohol is preferred. These alignment polymers may be used alone or in combination of two or more.

One method of rubbing is to bring a film of oriented polymer formed on the surface of a substrate layer by applying an oriented polymer composition to the substrate and annealing the composition into contact with a rotating rubbing roll wrapped with a rubbing cloth.

The photo-alignment layer is made of a polymer, oligomer, or monomer having a photoreactive group. The photo-alignment layer can obtain an alignment control force by irradiating it with polarized light. The photo-alignment layer is more preferable in that the direction of the alignment control force can be freely controlled by selecting the polarization direction of the irradiated polarized light.

The photoreactive group is a group that generates liquid crystal alignment ability by irradiation with light. Specifically, it is a group that generates a photoreaction that is the origin of liquid crystal alignment ability, such as molecular alignment induction or isomerization reaction, dimerization reaction, photocrosslinking reaction, or photodecomposition reaction, which occurs by irradiation with light. Among the photoreactive groups, those that cause a dimerization reaction or a photocrosslinking reaction are preferred in terms of excellent alignment ability. As the photoreactive group that can generate the above-mentioned reaction, those having an unsaturated bond, especially a double bond, are preferred, and groups having at least one selected from the group consisting of a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond), and a carbon-oxygen double bond (C=O bond) are more preferred.

Examples of photoreactive groups having a C=C bond include vinyl groups, polyene groups, stilbene groups, stilbazolyl groups, stilbazolium groups, chalcone groups, and cinnamoyl groups. From the viewpoint of easy control of reactivity and the expression of alignment control force during photoalignment, chalcone groups and cinnamoyl groups are preferred. Examples of photoreactive groups having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, and formazan groups, as well as groups having azoxybenzene as a basic structure. Examples of photoreactive groups having a C=O bond include benzophenone groups, coumarin groups, anthraquinone groups, and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and halogenated alkyl groups.

The polarized light may be irradiated directly from the film surface, or may be irradiated from the substrate layer side and then transmitted through the film. It is particularly preferable that the polarized light is substantially parallel light. The polarized light to be irradiated is preferably in a wavelength range in which the photoreactive group of the polymer or monomer having a photoreactive group can absorb light energy. Specifically, UV (ultraviolet light) having a wavelength of 250 to 400 nm is particularly preferable. Examples of light sources used for the polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, ultraviolet lasers such as KrF and ArF, and high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps are more preferable. These lamps are preferable because the emission intensity of ultraviolet light with a wavelength of 313 nm is high. Polarized light can be irradiated by irradiating the light from the light source through an appropriate polarizer. As such a polarizer, a polarizing filter, a polarizing prism such as Glan-Thompson or Glan-Taylor, or a wire grid type polarizer can be used.
<Polarizing Plate>
A polarizing plate is a film having an optical absorption anisotropy function, and is generally a film including a polarizing element in which a dichroic dye is uniaxially oriented. In order to uniaxially align a dichroic dye, a polarizer can be prepared from a film that is uniaxially stretched in a state in which iodine or an organic dichroic dye is impregnated in a polymer such as a polyvinyl alcohol (PVA) resin, or a liquid crystal polarizer that is an optically anisotropic layer formed by orienting a dichroic dye and a polymerizable liquid crystal compound. That is, the polarizing function is exhibited by anisotropically absorbing light by the dichroic dye included in the polymer of the stretched polymer or the polymerizable liquid crystal compound.

The polarizing plate includes a polarizing element and may have a polarizing element protective film or layer on one or both sides of the polarizing element.

The polarization performance of the polarizing plate can be measured using a spectrophotometer. For example, the transmittance (T1) in the transmission axis direction (direction perpendicular to the orientation) and the transmittance (T2) in the absorption axis direction (direction of orientation) in the visible light wavelength range of 380 nm to 780 nm can be measured by a double beam method using a device in which a prism polarizer is set in a spectrophotometer. The polarization performance in the visible light range can be calculated as the luminosity-corrected single transmittance (Ty) and luminosity-corrected polarization degree (Py) by calculating the single transmittance and the degree of polarization at each wavelength using the following formulas (Formula 1) and (Formula 2), and further performing luminosity correction using a 2-degree visual field (C light source) according to JIS Z 8701. Similarly, the chromaticity a ^* and b ^* in the L ^* a ^* b ^* (CIE) color system are calculated from the transmittance measured in the same manner using the color matching function of the C light source to obtain the hue of the polarizing plate alone (single hue), the hue when the polarizing plates are arranged in parallel (parallel hue), and the hue when the polarizing plates are arranged perpendicularly (orthogonal hue). The closer the values of ^a* and b ^* are to 0, the more neutral the hue is.
Single-piece transmittance (%)=(T1+T2)/2 (Formula 1)
Degree of polarization (%) = (T1-T2)/(T1+T2)×100 (Formula 2)

The luminosity-corrected polarization degree Py of the polarizing plate is usually 80% or more, preferably 90% or more, more preferably 95% or more, even more preferably 98% or more, and particularly preferably 99% or more. If it is 99.9% or more, it can be suitably used in a liquid crystal display. Increasing the luminosity-corrected polarization degree Py of the polarizing plate is advantageous in enhancing the anti-reflection function of the optical laminate. If the luminosity-corrected polarization degree Py is less than 80%, the optical laminate may not be able to perform the anti-reflection function when used as an anti-reflection film.

The greater the luminosity-corrected single transmittance Ty of the polarizing plate, the greater the clarity of the white display. However, as can be seen from the relationship between (Equation 1) and (Equation 2), if the single transmittance is too high, there is a problem that the degree of polarization decreases. Therefore, it is preferably 30% to 60%, more preferably 35% to 55%, even more preferably 38% to 50%, and even more preferably 40% to 45%. If the luminosity-corrected single transmittance Ty is excessively large, the luminosity-corrected polarization degree Py becomes too small, and the anti-reflection function may be insufficient when the optical laminate is used as an anti-reflection film.

(Polarizing element)
As described above, the polarizing element may be a polarizer or a liquid crystal polarizer. The polarizing element is preferably a polarizer.

(Polarizer)
A polarizer, that is, a film obtained by uniaxially stretching a polymer such as a polyvinyl alcohol (PVA)-based resin film impregnated with iodine or an organic dichroic dye, can usually be produced through a process of uniaxially stretching a polyvinyl alcohol-based resin film, a process of dyeing the polyvinyl alcohol-based resin film with a dichroic dye such as iodine to adsorb the dichroic dye, a process of treating the polyvinyl alcohol-based resin film with the adsorbed dichroic dye with a crosslinking agent such as a boric acid-containing aqueous solution, and a process of washing with water after the treatment with the crosslinking agent such as a boric acid-containing aqueous solution. The polarizer may contain a crosslinking agent.

The thickness of the polarizer is usually 30 μm or less, preferably 18 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The thickness is usually 1 μm or more, for example, 5 μm or more.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing with a dichroic dye. When the uniaxial stretching is performed after dyeing, the uniaxial stretching may be performed before or during the boric acid treatment. Of course, the uniaxial stretching can be performed in the multiple stages shown here. For the uniaxial stretching, a method of uniaxially stretching in the film transport direction between rolls with different peripheral speeds, a method of uniaxially stretching in the film transport direction using a heated roll, or a method of stretching in the width direction using a tenter can be used. The uniaxial stretching may be performed by dry stretching in the air, or by wet stretching in a state in which the polyvinyl alcohol-based resin film is swollen using a solvent such as water. The stretching ratio is usually 3 to 8 times. In addition, an aqueous solution containing polyvinyl alcohol may be applied to the thermoplastic resin film, followed by drying, and then stretched together with the thermoplastic resin film by the above method.

Dyeing of a polyvinyl alcohol-based resin film with a dichroic dye can be carried out, for example, by immersing the polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic dye. Specific examples of the dichroic dye that can be used include iodine and dichroic organic dyes.

(Method of Manufacturing Polarizer)
A polarizer is usually produced through a step of uniaxially stretching a polyvinyl alcohol-based resin film (hereinafter also referred to as a "PVA-based film"), a step of dyeing the PVA-based film with a dichroic dye to adsorb the dichroic dye, a step of treating the PVA-based film with the dichroic dye-adsorbed thereon with a boric acid-containing aqueous solution to crosslink the film, and a step of washing with water after the crosslinking treatment with the boric acid-containing aqueous solution (hereinafter also referred to as a "boric acid treatment").

The uniaxial stretching of the PVA-based film can be performed before, simultaneously with, or after dyeing with a dichroic dye. When the uniaxial stretching is performed after dyeing, it may be performed before or during the boric acid treatment. Of course, the uniaxial stretching can be performed in multiple stages as shown here. For the uniaxial stretching, a method of uniaxially stretching in the film transport direction between rolls with different peripheral speeds, a method of uniaxially stretching in the film transport direction using a heated roll, or a method of stretching in the width direction using a tenter can be used. The uniaxial stretching can be performed by dry stretching in the air, or by wet stretching in which the PVA-based film is stretched in a swollen state using a solvent such as water. The stretching ratio is usually 3 to 8 times.

Dyeing of a PVA-based film with a dichroic dye can be carried out, for example, by immersing the PVA-based film in an aqueous solution containing the dichroic dye. Specific examples of the dichroic dye that can be used include iodine and dichroic organic dyes. It is preferable to immerse the PVA-based film in water to cause it to swell before the dyeing process.

When iodine is used as the dichroic dye, a method is usually used in which the PVA-based film is immersed in an aqueous solution containing iodine and potassium iodide to dye it. The iodine content in this aqueous solution is usually 0.01 to 1 part by mass per 100 parts by mass of water, and the potassium iodide content is usually 0.5 to 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution used for dyeing is usually 20 to 40°C. The immersion time in this aqueous solution (dyeing time) is usually 20 to 1,800 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic pigment, a method is usually adopted in which the PVA-based film is immersed in an aqueous solution containing a water-soluble dichroic organic dye to dye it. The content of the dichroic organic dye in this aqueous solution is usually 0.0001 to 10 parts by mass, and preferably 0.001 to 1 part by mass, per 100 parts by mass of water. This aqueous dye solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic organic dye solution used for dyeing is usually 20 to 80°C. The immersion time in this aqueous solution (dyeing time) is usually 10 to 1800 seconds.

The boric acid treatment after dyeing with a dichroic dye can be carried out by immersing the dyed PVA-based film in a boric acid-containing aqueous solution. The content of boric acid in the boric acid-containing aqueous solution is usually 2 to 15 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of water. When iodine is used as the dichroic dye, it is preferable that the boric acid-containing aqueous solution contains potassium iodide. The content of potassium iodide in the boric acid-containing aqueous solution is usually 0.1 to 15 parts by mass, preferably 5 to 12 parts by mass, per 100 parts by mass of water. The immersion time in the boric acid-containing aqueous solution is usually 60 to 1200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50°C or higher, preferably 50 to 85°C, and more preferably 60 to 80°C.

After the boric acid treatment, the PVA-based film is usually washed with water. The washing can be carried out, for example, by immersing the boric acid-treated PVA-based film in water. The temperature of the water used in the washing is usually 5 to 40°C. The immersion time is usually 1 to 120 seconds.

After washing with water, a drying process is performed to obtain a polarizer. The drying process can be performed using a hot air dryer or a far infrared heater. The temperature of the drying process is usually 30 to 100°C, preferably 50 to 80°C. The time of the drying process is usually 60 to 600 seconds, preferably 120 to 600 seconds. The moisture content in the polarizer is reduced to a practical level by the drying process. The moisture content is usually 5 to 20 mass% and preferably 8 to 15 mass% with respect to the total mass of the polarizer. If the moisture content is 5 mass% or more, the polarizer has sufficient flexibility, and therefore damage or breakage after drying can be suppressed. Furthermore, if the moisture content is 20 mass% or less, the polarizer has sufficient thermal stability.

In this way, a polarizer can be produced in which a dichroic dye is adsorbed and oriented on a PVA-based film.

The polarizer obtained above can be further laminated with a polarizing element protective film or protective layer on one or both sides to produce a polarizing plate.

(Liquid Crystal Polarizer)
A liquid crystal polarizer, i.e., an optically anisotropic layer made of a polymer of a polymerizable liquid crystal compound containing a dichroic dye, can be suitably used for, for example, flexible displays, since the hue can be arbitrarily controlled, the thickness can be significantly reduced, and the layer is non-shrinkable since it is not stretched or relaxed by heat.

The liquid crystal polarizer is formed by applying a liquid crystal polarizer-forming composition onto the third substrate layer or onto the third alignment layer formed on the third substrate layer, and orienting the dichroic dye contained in the liquid crystal polarizer-forming composition. The thickness of the liquid crystal polarizer is preferably 0.1 μm or more and 5 μm or less, more preferably 0.3 μm or more and 4 μm or less, and even more preferably 0.5 μm or more and 3 μm or less. If the thickness is smaller than the above range, the necessary light absorption may not be obtained, and if the thickness is larger than the above range, the alignment control force by the third alignment layer decreases, and alignment defects tend to occur easily. In addition, the liquid crystal polarizer-forming composition may further contain a solvent, a photopolymerization initiator, a photosensitizer, a polymerization inhibitor, a leveling agent, an adhesion improver, etc.

In a liquid crystal polarizer in which the dichroic dye and polymerizable liquid crystal compound are aligned horizontally relative to the surface of the third substrate layer, the ratio (dichroic ratio) of the absorbance A1 (λ) in the alignment direction for light with a wavelength of λ nm to the absorbance A2 (λ) in the vertical direction within the alignment plane is preferably 7 or more, more preferably 20 or more, and even more preferably 40 or more. The higher the value of this ratio, the more excellent the absorption selectivity of the liquid crystal polarizer. Depending on the type of dichroic dye, when the polymerizable liquid crystal compound that constitutes the liquid crystal polarizer is cured in a nematic liquid crystal phase state, the above ratio is about 5 to 10.

By mixing two or more dichroic dyes with different absorption wavelengths, it is possible to produce liquid crystal polarizers of various hues, and liquid crystal polarizers that absorb the entire visible light range can be produced. By producing liquid crystal polarizers with such absorption characteristics, they can be used in a variety of applications.

(Polymerizable Liquid Crystal Compound Constituting Liquid Crystal Polarizer)
The polymerizable liquid crystal compound is a compound having a polymerizable group and liquid crystallinity. The polymerizable group means a group involved in a polymerization reaction, and is preferably a photopolymerizable group. Here, the photopolymerizable group means a group that can be involved in a polymerization reaction by an active radical or an acid generated from a photopolymerization initiator described later. Examples of the polymerizable group include a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, an acryloyloxy group, a methacryloyloxy group, an oxiranyl group, and an oxetanyl group. Among them, an acryloyloxy group, a methacryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferred, and a methacryloyloxy group or an acryloyloxy group is more preferred. The liquid crystallinity may be a thermotropic liquid crystal or a lyotropic liquid crystal, but when mixed with a dichroic dye described later, a thermotropic liquid crystal is preferred. The polymerizable liquid crystal compound may be a monomer, or may be a polymer polymerized to form a dimer or more.

When the polymerizable liquid crystal compound is a thermotropic liquid crystal, it may be a thermotropic liquid crystal compound exhibiting a nematic liquid crystal phase, or a thermotropic liquid crystal compound exhibiting a smectic liquid crystal phase. From the viewpoint of being able to exhibit high dichroism, the liquid crystal state exhibited by the polymerizable liquid crystal compound is preferably a smectic phase, and a high-order smectic phase is more preferable from the viewpoint of improving performance. Among them, a high-order smectic polymerizable liquid crystal compound that forms a smectic B phase, a smectic D phase, a smectic E phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic I phase, a smectic J phase, a smectic K phase, or a smectic L phase is more preferable, and a high-order smectic polymerizable liquid crystal compound that forms a smectic B phase, a smectic F phase, or a smectic I phase is even more preferable. When the liquid crystal phase formed by the polymerizable liquid crystal compound is one of these high-order smectic phases, a liquid crystal polarizer with higher polarization performance can be manufactured. Furthermore, such liquid crystal polarizers with high polarization performance are capable of obtaining Bragg peaks derived from higher-order structures such as hexatic and crystalline phases in X-ray diffraction measurements. The Bragg peaks are peaks derived from the periodic structure of molecular orientation, and a film with a periodic interval of 3 to 6 Å can be obtained. It is preferable for the liquid crystal polarizer to contain a polymer of the polymerizable liquid crystal compound oriented in a smectic phase, from the viewpoint of obtaining higher polarization characteristics.

The polymerizable liquid crystal compound may be used alone or in combination of two or more. The composition for forming a liquid crystal polarizer containing other compounds described later may contain other polymerizable liquid crystal compounds other than the polymerizable liquid crystal compound as long as the effect of the present invention is not impaired. From the viewpoint of obtaining a liquid crystal polarizer with a high degree of orientation order, the ratio of the polymerizable liquid crystal compound (polymerizable liquid crystal compound other than other polymerizable liquid crystal compounds) to the total mass of all polymerizable liquid crystal compounds contained in the composition for forming a liquid crystal polarizer is preferably 51% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.

The content of the polymerizable liquid crystal compound in the composition for forming a liquid crystal polarizer is preferably 40 to 99.9% by mass, more preferably 60 to 99% by mass, and even more preferably 70 to 99% by mass, based on the solid content of the polymerizable liquid crystal composition. When the content of the polymerizable liquid crystal compound is within the above range, the orientation of the polymerizable liquid crystal compound tends to be high. In this specification, the solid content refers to the total amount of components excluding the solvent from the composition for forming a liquid crystal polarizer.

(Dichroic dyes constituting liquid crystal polarizers)
A dichroic dye refers to a dye having different absorbance in the long axis direction of the molecule and absorbance in the short axis direction. As a dichroic dye, a dye having a characteristic of absorbing visible light is preferable, and a dye having a maximum absorption wavelength (λMAX) in the wavelength range of 380 to 680 nm is more preferable. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes, and among them, azo dyes are preferable. Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbene azo dyes, and the like, and bisazo dyes and trisazo dyes are preferable. The dichroic dyes may be used alone or in combination, but in order to obtain absorption over the entire visible light range, it is preferable to combine two or more dichroic dyes, and more preferably to combine three or more dichroic dyes.

An example of the azo dye is a compound represented by formula (VIII) (hereinafter, sometimes referred to as "compound (VIII)").
T ¹ -A ¹ (-N=NA ² ) _p -N=NA ³ -T ² (VIII)
[In formula (VIII),
A ¹ , A ² , and A ³ each independently represent a 1,4-phenylene group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent, a benzoic acid phenyl ester group which may have a substituent, a 4,4′-stilbenylene group which may have a substituent, or a divalent heterocyclic group which may have a substituent.
^T1 and ^T2 are, independently of each other, electron withdrawing or electron releasing groups and are oriented at substantially 180° to the plane of the azo bond.
p represents an integer of 0 to 4. When p is 2 or more, each ^A2 may be the same or different. The -N=N- bond may be replaced with a -C=C-, -COO-, -NHCO-, or -N=CH- bond as long as the compound exhibits absorption in the visible range.]

The content of the dichroic dye (the total amount when multiple types are included) is usually 1 to 60 parts by mass, preferably 1 to 40 parts by mass, and more preferably 1 to 20 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound, from the viewpoint of obtaining good light absorption characteristics. If the content of the dichroic dye is less than this range, light absorption will be insufficient and sufficient polarization performance will not be obtained, and if the content is more than this range, the alignment of the liquid crystal molecules may be hindered.

The liquid crystal polarizer can be manufactured by applying a liquid crystal polarizer-forming composition onto the third substrate layer or onto the third alignment layer formed on the third substrate layer. The liquid crystal polarizer-forming composition may further contain additives such as a solvent, a leveling agent, a polymerization initiator, a photosensitizer, an antioxidant, a crosslinking agent, an adhesive agent, and other reactive additives, and it is preferable from the viewpoint of processability that the composition contains a solvent and a leveling agent. As these additives, those described in the liquid crystal retardation layer-forming composition can be used.

Examples of the method for applying the composition for forming a liquid crystal polarizer, the method for drying the composition for forming a liquid crystal polarizer to remove the solvent contained therein, and the method for polymerizing the polymerizable liquid crystal compound contained in the composition for forming a liquid crystal polarizer include the methods described in the method for manufacturing a liquid crystal retardation layer. Examples of the third substrate layer and the third alignment layer include the first substrate layer and the second substrate layer described in the method for manufacturing a liquid crystal retardation layer, and the first alignment layer and the second alignment layer described in the method for manufacturing a liquid crystal retardation layer.

A polarizing plate can be manufactured by laminating a polarizing element protective film or protective layer on one or both sides of a liquid crystal polarizer.

(Polarizing element protective film)
The polarizing element protective film has a function of protecting the surface of the polarizing element. The polarizing element and the polarizing element protective film may be directly laminated to each other. Here, "directly laminated" includes an embodiment in which the polarizing element protective film is laminated to the polarizing element by the self-adhesiveness of the polarizing element protective film, and an embodiment in which the polarizing element protective film is laminated via a pressure-sensitive adhesive layer (adhesive layer or pressure-sensitive adhesive layer). The polarizing element protective film may be subjected to a surface treatment (e.g., corona treatment, etc.) to improve adhesion to the polarizing element, and a thin layer such as a primer layer (also called an "easy adhesion layer") may be formed.

As the polarizing element protective film, for example, a resin film having excellent transparency, mechanical strength, thermal stability, moisture blocking properties, isotropy, stretchability, etc. can be used. The resin film may be a thermoplastic resin film. Specific examples of resins constituting such a resin film include cellulose-based resins such as triacetyl cellulose; polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate; polyethersulfone-based resins; polysulfone-based resins; polycarbonate-based resins; polyamide-based resins such as nylon and aromatic polyamide; polyimide-based resins; polyolefin-based resins such as polyethylene, polypropylene, and ethylene-propylene copolymers; cyclic polyolefin-based resins having cyclo- and norbornene structures (also called "norbornene-based resins"); (meth)acrylic resins such as polymethyl methacrylate; polyarylate-based resins; polystyrene-based resins; polyvinyl alcohol-based resins, and mixtures thereof. Polarizing element protective films made of such materials are easily available on the market. Other examples include thermosetting resins or ultraviolet-curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone. In this specification, (meth)acrylic means either acrylic or methacrylic. The same applies to the notations (meth)acrylate and (meth)acryloyl.

Examples of linear polyolefin resins include linear olefin homopolymers such as polyethylene resins (polyethylene resins which are homopolymers of ethylene, and copolymers mainly composed of ethylene) and polypropylene resins (polypropylene resins which are homopolymers of propylene, and copolymers mainly composed of propylene), as well as copolymers made of two or more linear olefins.

Cyclic polyolefin resin is a general term for resins polymerized using cyclic olefins as polymerization units, and examples of such resins include those described in JP-A-1-240517, JP-A-3-14882, and JP-A-3-122137. Specific examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers (typically random copolymers) of cyclic olefins with linear olefins such as ethylene and propylene, and graft polymers modified with unsaturated carboxylic acids or their derivatives, as well as hydrogenated products thereof. Of these, norbornene resins using norbornene monomers such as norbornene or polycyclic norbornene monomers as the cyclic olefin are preferably used.

Polyester resins are resins with ester bonds in the main chain, and are generally polycondensates of polyvalent carboxylic acids or their derivatives with polyhydric alcohols. As polyvalent carboxylic acids or their derivatives, divalent dicarboxylic acids or their derivatives can be used, such as terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. As polyhydric alcohols, divalent diols can be used, such as ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A representative example of polyester resins is polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

Cellulose ester resins are esters of cellulose and fatty acids. Specific examples of cellulose ester resins include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Other examples include copolymers having multiple types of polymerization units constituting these cellulose ester resins, and resins in which some of the hydroxyl groups have been modified with other substituents. Among these, cellulose triacetate (triacetyl cellulose) is particularly preferred.

The (meth)acrylic resin is a resin whose main constituent monomer is a compound having a (meth)acryloyl group. Specific examples of the (meth)acrylic resin include poly(meth)acrylic acid ester such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymer; methyl methacrylate-(meth)acrylic acid ester copolymer; methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymer; methyl (meth)acrylate-styrene copolymer (MS resin, etc.); and copolymers of methyl methacrylate and compounds having alicyclic hydrocarbon groups (e.g. methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). Preferably, a polymer whose main component is poly(meth)acrylic acid C _1-6 alkyl ester such as polymethyl (meth)acrylate is used, and more preferably, a methyl methacrylate resin whose main component is methyl methacrylate (50 to 100% by weight, preferably 70 to 100% by weight) is used.

Polycarbonate-based resins consist of polymers in which monomer units are bonded via carbonate groups. The polycarbonate-based resin may be a resin called a modified polycarbonate, in which the polymer backbone has been modified, or a copolymer polycarbonate. Examples of polycarbonate-based resins include those described in JP 2012-31370 A.

The thickness of the polarizing element protective film is preferably 0.1 μm to 60 μm, more preferably 0.5 μm to 40 μm, and even more preferably 1 μm to 30 μm.

The polarizing element protective film can be used by being disposed so as to be on the viewing side of the polarizing element. Therefore, the polarizing element protective film may be subjected to surface treatments such as hard coat treatment, anti-reflection treatment, anti-sticking treatment, and anti-glare treatment, as necessary. Furthermore/alternatively, the polarizing element protective film may be subjected to treatments (typically, imparting an (elliptical) polarization function, imparting an ultra-high phase difference) to improve visibility when viewed through polarized sunglasses, as necessary. By performing such treatments, excellent visibility can be achieved even when the display screen is viewed through polarized lenses such as polarized sunglasses. Therefore, a polarizing plate equipped with a polarizing element protective film having a phase difference can be suitably applied to image display devices that can be used outdoors.

A polarizing element protective film can be produced by stretching a film containing the above thermoplastic resin. Examples of stretching treatment include uniaxial stretching treatment and biaxial stretching treatment. Examples of stretching directions include the machine flow direction (MD) of the unstretched film, a direction perpendicular to the MD (TD), and a direction oblique to the machine flow direction (MD). Biaxial stretching may be simultaneous biaxial stretching in which the film is stretched in two stretching directions at the same time, or sequential biaxial stretching in which the film is stretched in a predetermined direction and then stretched in the other direction. The stretching treatment can be performed, for example, by using two or more pairs of nip rolls with a high peripheral speed on the outlet side to stretch the film in the longitudinal direction (machine flow direction: MD), or by gripping both side ends of the unstretched film with chucks to spread it in the direction perpendicular to the machine flow direction (TD). At this time, the retardation value and wavelength dispersion can be controlled by adjusting the thickness of the film or the stretching ratio. In addition, the wavelength dispersion value can be controlled by adding a wavelength dispersion adjuster to the resin.

The polarizing element protective film may contain any suitable additive depending on the purpose. Examples of additives include antioxidants such as hindered phenols, phosphorus, and sulfur, stabilizers such as light stabilizers, ultraviolet absorbers, weather stabilizers, and heat stabilizers; reinforcing materials such as glass fibers and carbon fibers; near-infrared absorbers; flame retardants such as tris(dibromopropyl)phosphate, triallyl phosphate, and antimony oxide; antistatic agents such as anionic, cationic, and nonionic surfactants; colorants such as inorganic pigments, organic pigments, and dyes; organic and inorganic fillers; resin modifiers; plasticizers; lubricants; retardation reducers, and the like. The types, combinations, and amounts of additives contained may be appropriately set depending on the purpose and desired characteristics.

In order to impart desired surface optical properties or other characteristics, a coating layer (surface treatment layer) can be provided on the outer surface of the polarizing element protective film. Specific examples of the surface treatment layer include a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer. There are no particular limitations on the method for forming the surface treatment layer, and known methods can be used. The surface treatment layer may be formed on one surface or both surfaces of the polarizing element protective film.

The hard coat layer has the function of increasing the surface hardness of the polarizing element protective film, and is provided for the purpose of preventing surface scratches, etc. It is preferable that the hard coat layer has a pencil hardness of H or harder as measured by the pencil hardness test (measured by placing an optical film having a hard coat layer on a glass plate) specified in JIS K 5600-5-4:1999 "General test methods for paints - Part 5: Mechanical properties of coatings - Section 4: Scratch hardness (pencil method)"

The material that forms the hard coat layer is generally cured by heat or light. Examples include organic hard coat materials such as organic silicone-based, melamine-based, epoxy-based, (meth)acrylic-based, and urethane (meth)acrylate-based, and inorganic hard coat materials such as silicon dioxide. Among these, urethane (meth)acrylate-based or multifunctional (meth)acrylate-based hard coat materials are preferably used because they have good adhesion to the polarizing element protective film and are highly productive.

The hard coat layer may contain various fillers as desired to adjust the refractive index, improve the flexural modulus, stabilize the volumetric shrinkage rate, and further improve heat resistance, antistatic properties, antiglare properties, etc. The hard coat layer may also contain additives such as antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, leveling agents, and defoamers.

The hard coat layer may contain additives to further improve its strength. The additives are not limited, and examples include inorganic fine particles, organic fine particles, and mixtures thereof. The thickness of the hard coat layer is preferably thicker in order to provide hardness, but if it is too thick, it will be prone to cracking when cut, so the thickness is, for example, 1 μm to 20 μm, and may be 2 μm to 10 μm. The thickness of the hard coat layer is preferably 3 μm to 7 μm.

The antiglare layer is a layer having a finely uneven surface, and is preferably formed using the material for forming the hard coat layer described above.

An anti-glare layer having a finely uneven surface can be formed by 1) forming a coating film containing fine particles on a stretched film and providing the uneven surface based on the fine particles, or 2) forming a coating film, which may or may not contain fine particles, on a stretched film, and then pressing the film against a mold (such as a roll) that has been given an uneven surface to transfer the uneven surface (also called an embossing method).

The anti-reflection layer is a layer that weakens the reflection of external light on the surface of the polarizing element protective film for a person observing the polarizing element protective film, and typically has a reflectance of 1.5% or less for visible light. An anti-reflection layer with such reflectance can typically be obtained by laminating a high refractive index layer having a high refractive index and a low refractive index layer having a low refractive index, or by using the method and materials described in JP 2021-6929 A. By adjusting these refractive indices and the thickness of each layer, the reflected light from each layer can be weakened by each other, providing excellent anti-reflection functionality.

It is preferable to manufacture the anti-reflection layer consisting of a high refractive index layer and a low refractive index layer using a coating composition capable of forming each of the high refractive index layer and the low refractive index layer, since the operation is extremely simple. Here, an example of a coating composition capable of forming each of the high refractive index layer and the low refractive index layer will be given. Such a coating composition is liquid and contains an appropriate curable resin and, if necessary, an additive. A coating composition capable of forming a high refractive index layer (a composition for forming a high refractive index layer) is, for example, a curable resin such as urethane acrylate, and an initiator for photopolymerization (photopolymerization initiator) such as an acetophenone type, a benzophenone type, a benzyl dimethyl ketal type, an α-hydroxyalkylphenone type, an α-aminoalkylphenone type, or a thioxanthone type, dissolved in a solvent such as methyl ethyl ketone or methyl isobutyl ketone. In order to improve the coating property, a leveling agent, preferably a fluorine-based leveling agent, may be included. In addition, the coating composition capable of forming a low refractive index layer (composition for forming a low refractive index layer) is a binder resin such as polyethylene glycol diacrylate or pentaerythritol (tri/tetra)acrylate as a curable resin, and a photopolymerization initiator (photopolymerization initiator) such as acetophenone, benzophenone, benzyl dimethyl ketal, α-hydroxyalkylphenone, α-aminoalkylphenone, or thioxanthone is dissolved in a solvent such as 1-methoxy-2-propyl acetate or methyl isobutyl, and silica particles are dispersed in the solution. In order to improve the coating properties, a fluorine-based leveling agent may be contained. Note that the coating compositions capable of forming the high refractive index layer and the low refractive index layer listed here are merely examples, and it is preferable to optimize the composition for forming the high refractive index layer and the composition for forming the low refractive index layer, respectively, depending on the characteristics of the antireflection layer to be formed.

The antireflection layer may, for example, include a low refractive index layer. It may also have a multi-layer structure further including a high refractive index layer and/or a medium refractive index layer between the polarizing element protective film and the low refractive index layer.

The low refractive index layer can be formed by applying a coating liquid containing a cured product of the above-mentioned curable resin, a light-transmitting resin such as a metal alkoxide polymer, and inorganic particles, and then curing the coating layer as necessary. Examples of inorganic particles include low refractive index particles such as LiF (refractive index 1.4), MgF (refractive index 1.4), 3NaF·AlF (refractive index 1.4), AlF (refractive index 1.4), and Na ₃ AlF ₆ (refractive index 1.33), and hollow silica particles.

The antistatic layer is provided for the purpose of imparting electrical conductivity to the surface of the polarizing element protective film and suppressing the effects of static electricity. For example, the antistatic layer can be formed by applying a resin composition containing a conductive substance (antistatic agent) onto the polarizing element protective film. For example, an antistatic hard coat layer can be formed by adding an antistatic agent to the material for forming the hard coat layer described above.

The antifouling layer is provided to provide water repellency, oil repellency, sweat resistance, antifouling properties, etc. A suitable material for forming the antifouling layer is a fluorine-containing organic compound. Examples of fluorine-containing organic compounds include fluorocarbons, perfluorosilanes, and polymeric compounds thereof. Methods for forming the antifouling layer include physical vapor deposition methods, typically vapor deposition and sputtering, chemical vapor deposition methods, wet coating methods, etc., depending on the material to be formed. The average thickness of the antifouling layer is usually about 1 to 50 nm, and preferably 3 to 35 nm.

(Protective Layer)
The polarizing plate may have a protective layer on one or both sides of the polarizing element. When a liquid crystal polarizer is used as the polarizing element and the liquid crystal polarizer is laminated with another film by adhesion with a pressure-sensitive adhesive or the like, by providing a protective layer on the surface of the liquid crystal polarizer, it is possible to prevent low-molecular components such as unreacted polymerizable liquid crystal compounds and dichroic dyes in the liquid crystal polarizer from diffusing into another layer.

The protective layer is preferably thin if it can prevent low molecular weight components such as unreacted polymerizable liquid crystal compounds and dichroic dyes in the liquid crystal polarizer from diffusing into other layers. The thickness of the protective layer is preferably 0.1 μm or more and 10 μm or less, more preferably 0.1 μm or more and 5 μm or less, and even more preferably 0.1 μm or more and 3 μm or less.

The protective layer is preferably a polymer with a high crosslink density or a water-soluble polymer with high hydrophilic interaction. For example, it contains at least one selected from the group consisting of (meth)acrylic resin, epoxy resin, oxetane resin, urethane resin, melamine resin, and polyvinyl alcohol resin. Among these, from the viewpoint of excellent curability and ease of formation, it is preferable to contain at least one selected from the group consisting of (meth)acrylic resin, epoxy resin, oxetane resin, urethane resin, and melamine resin, and it is more preferable to contain at least one selected from the group consisting of (meth)acrylic resin and urethane resin. Also, from the viewpoint of hydrophilicity, polyvinyl alcohol resin is preferable.

<Adhesive layer (first adhesive layer, second adhesive layer)>
The adhesive layer (the first adhesive layer or the second adhesive layer) is preferably used when bonding a polarizing plate, a first liquid crystal retardation layer, a second liquid crystal retardation layer, etc. The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer or an adhesive layer.

(Adhesive Layer)
The adhesive layer exerts adhesiveness by attaching itself to an adherend, and is called a pressure-sensitive adhesive. As the adhesive composition forming the adhesive layer, a conventionally known adhesive composition having excellent optical transparency can be used without any particular limitation, and for example, an adhesive composition having a base polymer such as an acrylic resin, a urethane resin, a silicone resin, or a polyvinyl ether resin can be used. In addition, it may be an active energy ray curable adhesive composition, a heat curable adhesive composition, etc. Among these, an adhesive composition having an acrylic resin as a base polymer, which is excellent in transparency, adhesive strength, removability, weather resistance, heat resistance, etc., is preferable.
The pressure-sensitive adhesive composition may further contain a crosslinking agent, a silane compound, an antistatic agent, and the like.

The (meth)acrylic resin contained in the adhesive composition is preferably a polymer (hereinafter also referred to as a "(meth)acrylic acid ester polymer") whose main component is a structural unit derived from a (meth)acrylic acid alkyl ester represented by the following formula (IX) (hereinafter also referred to as "structural unit (IX)") (e.g., containing 50 parts by mass or more per 100 parts by mass of the structural unit of the (meth)acrylic resin).

［式（ＩＸ）中、
Ｒ^１０は、水素原子又はメチル基を表し、Ｒ^２０は、炭素数１～２０のアルキル基を表し、アルキル基は直鎖状、分岐状及び環状のうちのいずれの構造を有していてもよく、アルキル基の水素原子は、炭素数１～１０のアルコキシ基で置き換わっていてもよい。］

[In formula (IX),
R ¹⁰ represents a hydrogen atom or a methyl group, R ²⁰ represents an alkyl group having 1 to 20 carbon atoms, the alkyl group may have any of a linear, branched, and cyclic structure, and the hydrogen atom of the alkyl group may be replaced by an alkoxy group having 1 to 10 carbon atoms.

Examples of the (meth)acrylic acid ester represented by formula (IX) include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, i-hexyl (meth)acrylate, n-heptyl (meth)acrylate, and n -octyl (meth)acrylate, i-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n- and i-nonyl (meth)acrylate, n-decyl (meth)acrylate, i-decyl (meth)acrylate, n-dodecyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, stearyl (meth)acrylate, t-butyl (meth)acrylate, etc. Specific examples of alkoxy group-containing alkyl acrylates include 2-methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, etc. Among these, it is preferable to include n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate, and it is particularly preferable to include n-butyl (meth)acrylate.

The (meth)acrylic acid ester polymer may contain a structural unit derived from a monomer other than the structural unit (IX). The structural unit derived from the other monomer may be one type or two or more types. Examples of other monomers that the (meth)acrylic acid ester polymer may contain include a monomer having a polar functional group, a monomer having an aromatic group, and an acrylamide monomer.

Monomers having a polar functional group include (meth)acrylates having a polar functional group. Examples of the polar functional group include a hydroxy group; a carboxy group; an unsubstituted or substituted amino group substituted with an alkyl group having 1 to 6 carbon atoms; and a heterocyclic group such as an epoxy group.

The content of structural units derived from monomers having polar functional groups in the (meth)acrylic acid ester polymer is preferably 10 parts by mass or less, more preferably 0.5 parts by mass or more and 10 parts by mass or less, even more preferably 0.5 parts by mass or more and 5 parts by mass or less, and particularly preferably 1 part by mass or more and 5 parts by mass or less, relative to 100 parts by mass of all structural units of the (meth)acrylic acid ester polymer.

Examples of monomers having an aromatic group include (meth)acrylic acid esters having one (meth)acryloyl group and one or more aromatic rings (e.g., benzene ring, naphthalene ring, etc.) in the molecule, and having a phenyl group, a phenoxyethyl group, or a benzyl group.

The content of structural units derived from monomers having an aromatic group in the (meth)acrylic acid ester polymer is preferably 20 parts by mass or less, more preferably 4 parts by mass or more and 20 parts by mass or less, and even more preferably 4 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of all structural units of the (meth)acrylic acid ester polymer.

Examples of acrylamide monomers include N-(methoxymethyl)acrylamide, N-(ethoxymethyl)acrylamide, N-(propoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, and N-(2-methylpropoxymethyl)acrylamide. By including these structural units, it is possible to suppress the bleeding out of additives such as antistatic agents, which will be described later.

Furthermore, structural units derived from monomers other than structural unit (IX) may include structural units derived from styrene-based monomers, structural units derived from vinyl-based monomers, structural units derived from monomers having multiple (meth)acryloyl groups in the molecule, etc.

The weight average molecular weight (hereinafter also simply referred to as "Mw") of the (meth)acrylic resin is preferably 500,000 to 2,500,000. If the weight average molecular weight is 500,000 or more, the durability of the adhesive layer in high temperature and high humidity environments can be improved. If the weight average molecular weight is 2,500,000 or less, the operability when applying a coating liquid containing the adhesive composition is improved. The molecular weight distribution (Mw/Mn), which is expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (hereinafter also simply referred to as "Mn"), is usually 2 to 10. In this specification, "weight average molecular weight" and "number average molecular weight" are polystyrene-equivalent values measured by gel permeation chromatography (GPC).

When the (meth)acrylic resin is dissolved in ethyl acetate to prepare a solution having a concentration of 20% by mass, the viscosity at 25°C is preferably 20 Pa·s or less, and more preferably 0.1 to 15 Pa·s. If the viscosity of the (meth)acrylic resin at 25°C is within the above range, it contributes to improved durability and reworkability of the optical laminate including the pressure-sensitive adhesive layer formed from the resin. The above viscosity can be measured using a Brookfield viscometer.

The glass transition temperature (Tg) of the (meth)acrylic resin is, for example, −60 to 20° C., preferably −50 to 15° C., more preferably −45 to 10° C., and even more preferably −40 to 0° C. The glass transition temperature can be measured by a differential scanning calorimeter (DSC).

The (meth)acrylic resin may contain two or more types of (meth)acrylic acid ester polymers. Examples of such (meth)acrylic acid ester polymers include those that are mainly composed of structural units (IX) derived from the above-mentioned (meth)acrylic acid esters and have a relatively low molecular weight, such as a (meth)acrylic acid ester polymer with a weight average molecular weight in the range of 50,000 to 300,000.

(Meth)acrylic resins can usually be produced by known polymerization methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. In producing (meth)acrylic resins, polymerization is usually carried out in the presence of a polymerization initiator. The amount of polymerization initiator used is usually 0.001 to 5 parts by mass per 100 parts by mass of the total of all monomers constituting the (meth)acrylic resin. (Meth)acrylic resins can also be produced by a method of polymerization using active energy rays such as ultraviolet rays.

The pressure-sensitive adhesive composition preferably contains a crosslinking agent. Examples of crosslinking agents include conventional crosslinking agents (e.g., isocyanate compounds, epoxy compounds, aziridine compounds, metal chelate compounds, peroxides, etc.), and from the viewpoints of the pot life of the pressure-sensitive adhesive composition, crosslinking speed, and durability of the optical laminate, it is particularly preferable to use an isocyanate-based compound.

The isocyanate compound is a compound having at least two isocyanato groups (-NCO) in the molecule. Specific examples include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. In addition, adducts obtained by reacting these isocyanate compounds with polyols such as glycerol and trimethylolpropane, and dimers and trimers of these isocyanate compounds are also included. Two or more types of isocyanate compounds may be combined.

The content of the crosslinking agent in the pressure-sensitive adhesive composition is, for example, 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, and more preferably 0.1 to 1 part by mass, per 100 parts by mass of the (meth)acrylic resin.

The adhesive composition may further contain a silane compound. Examples of the silane compound include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylethoxydimethylsilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane. The silane compound may contain an oligomer derived from the above silane compound.

The content of the silane compound in the adhesive composition is usually 0.01 to 10 parts by mass, and preferably 0.05 to 5 parts by mass, per 100 parts by mass of the (meth)acrylic resin. When the content of the silane compound is 0.01 parts by mass or more, the adhesion between the adhesive layer and the adherend tends to be improved, and when the content is 10 parts by mass or less, bleeding out of the silane compound from the adhesive layer tends to be suppressed.

The pressure-sensitive adhesive composition may further include an antistatic agent. Examples of the antistatic agent include known ones, and ionic antistatic agents are preferred. Examples of the cationic component constituting the ionic antistatic agent include organic cations and inorganic cations. Examples of the organic cation include pyridinium cation, imidazolium cation, ammonium cation, sulfonium cation, phosphonium cation, etc. Examples of the inorganic cation include alkali metal cations such as lithium cation, potassium cation, sodium cation, and cesium cation, and alkaline earth metal cations such as magnesium cation and calcium cation. The anionic component constituting the ionic antistatic agent may be either an inorganic anion or an organic anion, but an anionic component containing a fluorine atom is preferred in terms of excellent antistatic performance. Examples of the anion component containing a fluorine atom include a hexafluorophosphate anion (PF ₆ ⁻ ), a bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N ⁻ ], and a bis(fluorosulfonyl)imide anion [(FSO ₂ ) ₂ N ⁻ ] anion.

Ionic antistatic agents that are solid at room temperature are preferred because they provide excellent stability over time of the antistatic performance of the pressure-sensitive adhesive composition.

The content of the antistatic agent in the pressure-sensitive adhesive composition is, for example, 0.01 to 20 parts by mass, preferably 0.1 to 10 parts by mass, and more preferably 1 to 7 parts by mass, per 100 parts by mass of the (meth)acrylic resin.

The adhesive composition may contain one or more additives such as ultraviolet absorbers, solvents, crosslinking catalysts, tackifiers, and plasticizers. It is also useful to blend an ultraviolet-curable compound into the adhesive composition, form an adhesive layer, and then irradiate the adhesive with ultraviolet light to cure the compound, thereby forming a harder adhesive layer.

The adhesive layer can be formed, for example, by dissolving or dispersing the adhesive composition in a solvent to form a solvent-containing adhesive composition, which is then applied to the surface of the layer on which the adhesive layer is to be formed, and then dried.

The thickness of the adhesive layer is usually 0.1 μm or more and 30 μm or less, preferably 3 μm or more and 30 μm or less, and more preferably 5 μm or more and 25 μm or less.

(Adhesive Layer)
The adhesive layer can have a function of bonding a polarizer and a polarizing element protective film, a function of bonding a polarizing plate, a first liquid crystal retardation layer, a second liquid crystal retardation layer, etc. The adhesive layer can be formed from an adhesive composition.

Examples of adhesive compositions include aqueous adhesive compositions, and curable adhesive compositions that are cured by heating or irradiation with active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. Examples of aqueous adhesive compositions include those in which a polyvinyl alcohol resin or a urethane resin is dissolved in water as the main component, and those in which a polyvinyl alcohol resin or a urethane resin is dispersed in water as the main component. The aqueous adhesive composition may further contain a curable component or a crosslinking agent such as a polyhydric aldehyde, a melamine compound, a zirconia compound, a zinc compound, a glyoxal compound, or a water-soluble epoxy resin. Examples of aqueous adhesive compositions include the adhesive composition described in JP 2010-191389 A, the adhesive composition described in JP 2011-107686 A, the composition described in JP 2020-172088 A, and the composition described in JP 2005-208456 A.

The curable adhesive composition is preferably an active energy ray curable adhesive composition that contains a curable (polymerizable) compound as a main component and is cured by irradiation with active energy rays. Examples of active energy ray curable adhesive compositions include cationic polymerization adhesive compositions that contain a cationic polymerizable compound as a curable compound, radical polymerization adhesive compositions that contain a radical polymerizable compound as a curable compound, and hybrid adhesive compositions that contain both a cationic polymerizable compound and a radical polymerizable compound as curable compounds.

A cationic polymerizable compound is a compound or oligomer that undergoes cationic polymerization reaction and hardens when exposed to active energy rays such as ultraviolet light, visible light, electron beams, or X-rays, or when heated. Specific examples include epoxy compounds, oxetane compounds, and vinyl compounds.

Epoxy compounds include alicyclic epoxy compounds (compounds having one or more epoxy groups bonded to an alicyclic ring in the molecule) such as 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate; aromatic epoxy compounds (compounds having an aromatic ring and an epoxy group in the molecule) such as diglycidyl ether of bisphenol A; and aliphatic epoxy compounds (compounds having at least one oxirane ring bonded to an aliphatic carbon atom in the molecule) such as 2-ethylhexyl glycidyl ether and 1,4-butanediol diglycidyl ether.

Examples of oxetane compounds include compounds that have one or more oxetane rings in the molecule, such as 3-ethyl-3-{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane.

The cationic polymerization adhesive composition preferably contains a cationic polymerization initiator. The cationic polymerization initiator may be a thermal cationic polymerization initiator or a photo-induced cationic polymerization initiator. Examples of the cationic polymerization initiator include aromatic diazonium salts such as benzenediazonium hexafluoroantimonate; aromatic iodonium salts such as diphenyliodonium tetrakis(pentafluorophenyl)borate; aromatic sulfonium salts such as triphenylsulfonium hexafluorophosphate; and iron-arene complexes such as xylene-cyclopentadienyl iron(II) hexafluoroantimonate. The content of the cationic polymerization initiator in the adhesive composition is usually 0.1 to 10 parts by mass per 100 parts by mass of the cationic polymerizable compound. Two or more types of cationic polymerization initiators may be included.

Examples of cationic polymerization adhesive compositions include the cationic polymerization composition described in JP 2021-113969 A.

Radically polymerizable compounds are compounds or oligomers that undergo a radical polymerization reaction and harden when exposed to active energy rays such as ultraviolet rays, visible light, electron beams, or X-rays, or when heated. Specific examples of compounds that have ethylenically unsaturated bonds include (meth)acrylic compounds that have one or more (meth)acryloyl groups in the molecule, and vinyl compounds that have one or more vinyl groups in the molecule.

Examples of (meth)acrylic compounds include (meth)acrylate monomers having at least one (meth)acryloyloxy group in the molecule, (meth)acrylamide monomers, and (meth)acryl group-containing compounds such as (meth)acrylic oligomers obtained by reacting two or more functional group-containing compounds and having at least two (meth)acryloyl groups in the molecule.

The radical polymerization adhesive composition preferably contains a radical polymerization initiator. The radical polymerization initiator may be a thermal radical polymerization initiator or a photoradical polymerization initiator. Examples of the radical polymerization initiator include acetophenone-based initiators such as acetophenone and 3-methylacetophenone; benzophenone-based initiators such as benzophenone, 4-chlorobenzophenone, and 4,4'-diaminobenzophenone; benzoin ether-based initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone-based initiators such as 4-isopropylthioxanthone; xanthone, fluorenone, and the like. The content of the radical polymerization initiator in the adhesive composition is usually 0.1 to 10 parts by mass per 100 parts by mass of the radical polymerizable compound. Two or more types of radical polymerization initiators may be included.

Examples of radical polymerization adhesive compositions include the radical polymerizable compositions described in JP 2016-126345 A, JP 2016-153474 A, and WO 2017/183335 A.

The active energy ray-curable adhesive composition may contain additives such as ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, flow control agents, plasticizers, defoamers, antistatic agents, leveling agents, and solvents, as necessary.

The bonding of two layers with an adhesive layer can be carried out by applying an adhesive composition to at least one of the bonding surfaces of each of the two layers, superimposing the two layers with the coating layer of the adhesive composition therebetween, pressing the layers together from above and below using a lamination roll or the like, and then drying the coating layer, curing it by irradiating it with active energy rays, or curing it by heating.

Before forming a coating layer of the adhesive composition, at least one of the bonding surfaces of the two layers may be subjected to an easy-adhesion treatment such as saponification treatment, corona treatment, plasma treatment, primer treatment, anchor coating treatment, etc.

A variety of coating methods can be used to form a coating layer of the adhesive composition, including a die coater, comma coater, gravure coater, wire bar coater, doctor blade coater, etc.

The irradiation intensity of the active energy rays when irradiating the active energy rays is determined for each composition of the active energy ray-curable adhesive composition and is not particularly limited, but is preferably 10 mW/ ^cm2 or more and ¹⁰⁰⁰ mW/cm2 or less. The irradiation intensity is preferably an intensity in a wavelength region effective for activating the photocationic polymerization initiator or the photoradical polymerization initiator. It is preferable to irradiate once or multiple times with such light irradiation intensity, and the integrated light amount is 10 mJ/ ^cm2 or more, and more preferably 100 mJ/cm2 or ^more and 1,000 mJ/ ^cm2 or less.

The light source used to polymerize and cure the active energy ray-curable adhesive composition is not particularly limited, but examples include low pressure mercury lamps, medium pressure mercury lamps, high pressure mercury lamps, ultra-high pressure mercury lamps, xenon lamps, halogen lamps, chemical lamps, black light lamps, microwave excited mercury lamps, and metal halide lamps.

The thickness of the adhesive layer formed from the aqueous adhesive composition may be, for example, 5 μm or less, preferably 1 μm or less, and more preferably 0.5 μm or less, and may be 0.01 μm or more, and preferably 0.05 μm or more.

The thickness of the adhesive layer formed from the active energy ray-curable adhesive composition may be, for example, 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less, and may be 0.1 μm or more, preferably 0.5 μm or more, and more preferably 1 μm or more.

The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" and "parts" in the examples and comparative examples mean "% by mass" and "parts by mass", respectively.

<Preparation of Polarizer>
(Preparation of Polarizer a)
A long polyvinyl alcohol (PVA) raw film having a thickness of 30 μm (trade name "Kuraray Poval Film VF-PE#3000" manufactured by Kuraray Co., Ltd., average polymerization degree 2400, saponification degree 99.9 mol% or more) was continuously transported while being unwound from a roll, and was immersed in a swelling bath of pure water at 20° C. for a residence time of 31 seconds (swelling step).Then, the film pulled out from the swelling bath was immersed in a dyeing bath containing iodine at 30° C. and potassium iodide/water at a weight ratio of 2/100 for a residence time of 122 seconds (dyeing step). Next, the film pulled out from the dyeing bath was immersed in a crosslinking bath at 56° C. with a potassium iodide/boric acid/water ratio of 12/4.1/100 (weight ratio) for a residence time of 70 seconds, and then in a crosslinking bath at 40° C. with a potassium iodide/boric acid/water ratio of 9/2.9/100 (weight ratio) for a residence time of 13 seconds (crosslinking step). In the dyeing step and crosslinking step, longitudinal uniaxial stretching was performed by inter-roll stretching in the bath. The total stretching ratio based on the original film was 5.4 times.

Next, the film pulled out from the crosslinking bath was immersed in a washing bath made of pure water at 5° C. for a residence time of 3 seconds (washing step), and then introduced into a first heating furnace capable of adjusting humidity, whereby a high-temperature, high-humidity treatment was performed for a residence time of 190 seconds (high-temperature, high-humidity treatment step). The film was further introduced into a second heating furnace, whereby a high-temperature, high-humidity treatment was performed for a residence time of 161 seconds, to obtain a polarizer a having a thickness of 12.9 μm and a width of 208 mm. The temperature and absolute humidity in the first heating furnace were 59° C. and 10 g/m ³ , respectively, and the film tension during the high-temperature, high-humidity treatment was 775 N/m. The temperature and absolute humidity in the second heating furnace were 73° C. and 89 g/m ³ , respectively, and the film tension during the high-temperature, high-humidity treatment was 1 N/m.

(Preparation of Polarizer b)
A polyvinyl alcohol film having a thickness of 20 μm, a degree of polymerization of 2400, and a degree of saponification of 99% or more was uniaxially stretched to a stretch ratio of 4.1 times on a heated roll, and while maintaining a tension state, was immersed in a dye bath containing 0.05 parts by mass of iodine and 5 parts by mass of potassium iodide per 100 parts by mass of water at 28 ° C. for 60 seconds. Next, it was immersed in an aqueous boric acid solution containing 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water at 64 ° C. for 110 seconds. Next, it was immersed in an aqueous boric acid solution containing 5.5 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water at 67 ° C. for 30 seconds. Thereafter, it was washed with pure water at 10 ° C. and dried to obtain a polarizer b. The thickness of the polarizer b was 8 μm.

[Measurement of polarizer shrinkage force]
The polarizer was cut into a rectangle with a short side of 2 mm and a long side of 50 mm by a super cutter (manufactured by Ogino Seiki Seisakusho Co., Ltd.) so that the absorption axis of the polarizer coincided with the long side, and a test specimen was obtained. The contraction force of the test specimen was measured using a thermomechanical analyzer (manufactured by SII Nanotechnology Co., Ltd., model TMA/6100). This measurement was performed in a constant dimension mode, with a chuck distance of 10 mm, a static load of 0 mN, and a SUS probe as a jig, in the following procedure. First, the test specimen was left in a room at a temperature of 20° C. for a sufficient period of time. Then, the temperature setting of the room in which the test specimen was placed was raised from 20° C. to 80° C. in 10 minutes. After the temperature increase, the room temperature was set to be maintained at 80° C., and the test specimen was left for another 4 hours, after which the contraction force of the test specimen in the long side direction (absorption axis direction) was measured in an environment at a temperature of 80° C. The results are shown in Tables 1 and 2.

<Preparation of Polarizing Plate>
(Preparation of Polarizing Plate a)
A cyclic polyolefin resin (COP) film (ZEON Corporation, Zeonor ZF14, thickness 13 μm) was attached to one side of the polarizer a as a polarizing element protective film via a water-based adhesive, and a triacetyl cellulose (TAC) film (FUJIFILM Corporation, Fujitac TJ25, thickness 25 μm) was attached to the other side of the polarizer a via a water-based adhesive. The resulting laminate was dried at 60° C. for 2 minutes while maintaining the tension of 430 N/m to obtain a polarizing plate a. The water-based adhesive was prepared by adding 3 parts of carboxyl group-modified polyvinyl alcohol (Kuraray Poval KL318, Kuraray) and 1.5 parts of water-soluble polyamide epoxy resin (Sumirez Resin 650, Sumika Chemtex Corporation, aqueous solution with a solid content of 30%) to 100 parts of water.

(Preparation of Polarizing Plate b)
A polarizing plate b having a laminate structure of COP film/adhesive layer/polarizer b/adhesive layer/TAC film was obtained in the same manner as in the preparation of polarizing plate a, except that polarizing plate b was used instead of polarizing plate a.

<Preparation of the first liquid crystal retardation layer (1), the second liquid crystal retardation layer (1), and the retardation body (1)>
(Preparation of Orientable Polymer Composition (1) (Composition for Forming Orientation Layer))
Water was added to commercially available polyvinyl alcohol (polyvinyl alcohol 1000 fully saponified type, manufactured by Wako Pure Chemical Industries, Ltd.), and the mixture was heated at 100° C. for 1 hour to obtain an oriented polymer composition (1).

(Preparation of second liquid crystal retardation layer forming composition (1))
Polymerizable liquid crystal compound (A1) and polymerizable liquid crystal compound (A2) having the structures shown below were prepared according to the method described in JP-A-2010-244038.

重合性液晶化合物（Ａ２）：

Polymerizable liquid crystal compound (A1):

Polymerizable liquid crystal compound (A2):

The polymerizable liquid crystal compound (A1) and the polymerizable liquid crystal compound (A2) were mixed in a mass ratio of 80:20 to obtain a mixture. 0.1 parts of a leveling agent "Megafac F-556" (manufactured by DIC Corporation), 2.5 parts of a photopolymerization initiator "Omnirad 907" (manufactured by IGM Resin B.V.), and 0.1 parts of an ionic compound (B) shown below were added to 100 parts of the obtained mixture. Furthermore, 650 parts of cyclopentanone were added to 100 parts of the mixture, and the mixture was stirred at a temperature of 80°C for 1 hour to prepare a second liquid crystal retardation layer forming composition (1).

Ionic Compound (B)

(Preparation of second liquid crystal retardation layer (1) with substrate)
A rectangular cut cycloolefin polymer (COP) film (ZF14, manufactured by Zeon Corporation) as the second substrate layer (1) was subjected to corona treatment using a corona treatment device (AGF-B10; manufactured by Kasuga Electric Co., Ltd.), and then an oriented polymer composition (1) was applied thereto. After drying by heating, a second orientation layer (1) of an oriented polymer having a thickness of 100 nm was formed. The surface of the second orientation layer (1) was subjected to rubbing treatment at an angle of 75° from the longitudinal direction of the COP film, and the second liquid crystal retardation layer forming composition (1) was applied thereon by a bar coater. The obtained second coating layer (1) was dried at 120 ° C. for 2 minutes to obtain a dried coating. Using a high-pressure mercury lamp ("Unicure VB-15201BY-A" manufactured by Ushio Inc.), the dried film was irradiated with ultraviolet light at an exposure dose of 1000 mJ/cm ² (based on 365 nm) at a temperature of 80° C. under a nitrogen atmosphere to form a second polymer layer (1) in which the optical axis of the polymerizable liquid crystal compound was aligned horizontally relative to the plane of the second substrate layer (1), and thus a substrate-attached second liquid crystal retardation layer (1) consisting of the second substrate layer (1)/second liquid crystal retardation layer (1) (second alignment layer (1)/second polymer layer (1)) was obtained.

The thickness of the obtained second polymer layer (1) was measured with a laser microscope and found to be 1.8 μm. The in-plane retardation value of the second liquid crystal retardation layer (1) with the substrate was measured using KOBRA-WR manufactured by Oji Scientific Instruments. As a result, the in-plane retardation value at a wavelength of 550 nm was Re(550)=270 nm. Note that the retardation value of the COP film, which is the second substrate layer (1), at a wavelength of 550 nm is approximately 0, so there is no effect on the optical properties of the second liquid crystal retardation layer (1) with the substrate. The orientation angle was 75° with respect to the longitudinal direction of the second substrate layer (1).

(Preparation of first liquid crystal retardation layer forming composition (1))
0.1 parts of a leveling agent "BYK-361N" (manufactured by BYK-Chemie) and 2.5 parts of a photopolymerization initiator "Omnirad907" (manufactured by IGM Resin B.V.) were added to 100 parts of the polymerizable liquid crystal compound Paliocolor LC242 (manufactured by BASF Japan) shown below. Furthermore, 400 parts of cyclopentanone were added to 100 parts of the polymerizable liquid crystal compound, and the mixture was stirred at a temperature of 80° C. for 1 hour to prepare a first liquid crystal retardation layer forming composition (1).

Polymerizable liquid crystal compound Paliocolor LC242:

(Preparation of the first liquid crystal retardation layer (1) with substrate)
A cycloolefin polymer (COP) film (ZF14, manufactured by Zeon Corporation) cut into a rectangle as the first substrate layer (1) was subjected to corona treatment using a corona treatment device (AGF-B10; manufactured by Kasuga Electric Co., Ltd.). The oriented polymer composition (1) was applied to the corona-treated surface of the COP film, and after drying by heating, a first orientation layer (1) of an oriented polymer having a thickness of 100 nm was formed. The surface of the obtained first orientation layer was subjected to rubbing treatment at an angle of 15° from the longitudinal direction of the COP film, and the first liquid crystal retardation layer forming composition (1) was applied thereon by a bar coater. The obtained first coating layer (1) was dried at 100 ° C. for 1 minute, and then cooled to room temperature to dry the first coating layer (1), and a first coating layer (1) with a substrate was obtained. Next, a high-pressure mercury lamp ("Uniqure VB-15201BY-A" manufactured by Ushio Inc.) was used to irradiate both sides of the substrate-attached first coating layer (1) with ultraviolet light under a nitrogen atmosphere (the total integrated light quantity of the ultraviolet light irradiated to both sides was 1000 mJ/cm ² (based on 365 nm)). This formed a first polymer layer (1) (horizontally aligned liquid crystal cured film) in which the polymerizable liquid crystal compound was cured in a state where it was aligned horizontally relative to the plane of the first substrate layer (1), thereby obtaining a substrate-attached first liquid crystal retardation layer (1) consisting of the first substrate layer (1)/first liquid crystal retardation layer (1) (first alignment layer (1)/first polymer layer (1)). The light transmittance of the first substrate layer (1) at a wavelength of 340 nm was measured using a UV-visible spectrophotometer ("UV-2450" manufactured by Shimadzu Corporation) and was found to be 90%.

The thickness of the obtained first polymer layer (1) was measured with a laser microscope and found to be 1.0 μm. The in-plane retardation value of the substrate-attached first liquid crystal retardation layer (1) was measured using KOBRA-WR manufactured by Oji Scientific Instruments. As a result, the in-plane retardation value at a wavelength of 550 nm was Re(550) = 140 nm. Note that the retardation value at a wavelength of 550 nm of the COP film, which is the first substrate layer (1), is approximately 0, and therefore does not affect the optical characteristics. The orientation angle was 15° with respect to the longitudinal direction of the first substrate layer (1).

[Measurement of surface hardness of first liquid crystal retardation layer]
The first substrate layer (1) and the first alignment layer (1) were peeled off from the substrate-attached first liquid crystal retardation layer (1) to remove the first liquid crystal retardation layer (1), which was then placed on glass. Using an ultra-microhardness tester (FISCHERSCOPE HM2000: manufactured by Fischer Instruments Co., Ltd.), a Vickers indenter was used to apply a load to the first liquid crystal retardation layer (1) on the glass at a pressure rate of 0.1 mN/10 seconds, and the load was maintained for 5 seconds to read the indentation modulus EIT [MPa], and the indentation elastic modulus [MPa] was measured, which was taken as the surface hardness. The indentation elastic modulus was also measured for the opposite surface of the first liquid crystal retardation layer (1) in the same manner, which was taken as the surface hardness. The measurement was performed at a temperature of 23°C. The surface of the first liquid crystal retardation layer (1) opposite to the first base layer (1) was defined as the first surface, and the surface of the first liquid crystal retardation layer (1) on the first base layer (1) side was defined as the second surface, and the ratio (H1/H2) of the surface hardness (H1) of the first surface to the surface hardness (H2) of the second surface was calculated. The results are shown in Tables 1 and 2.

(Preparation of active energy ray-curable adhesive composition (1))
The following components were blended and mixed, and then degassed to prepare an active energy ray-curable adhesive composition (1).
3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (product name: CEL2021P, manufactured by Daicel Corporation): 70 parts; Neopentyl glycol diglycidyl ether (product name: EX-211, manufactured by Nagase ChemteX Corporation): 20 parts; 2-ethylhexyl glycidyl ether (product name: EX-121, manufactured by Nagase ChemteX Corporation): 10 parts; Cationic polymerization initiator (product name: CPI-100 50% solution, manufactured by San-Apro Co., Ltd.): 4.5 parts (actual solid content 2.25 parts)
・1,4-diethoxynaphthalene: 2 parts

(Preparation of Retardation Body (1))
The second liquid crystal retardation layer (1) side of the second liquid crystal retardation layer (1) with the substrate and the first liquid crystal retardation layer (1) side of the first liquid crystal retardation layer (1) with the substrate were each subjected to a corona treatment. The active energy ray curable adhesive composition (1) prepared above was applied to one of the corona-treated surfaces, and the second liquid crystal retardation layer (1) of the second liquid crystal retardation layer (1) with the substrate and the first liquid crystal retardation layer (1) of the first liquid crystal retardation layer (1) with the substrate were bonded together. The active energy ray curable adhesive composition (1) was cured by irradiating ultraviolet light from the second liquid crystal retardation layer (1) with the substrate to form an adhesive layer (1) as a second adhesive layer. The ultraviolet light was irradiated so that the UVA with a wavelength of 320 nm to 390 nm was 420 mJ/cm ² . A retardation body (1) having a layer structure of the second base layer (1)/second liquid crystal retardation layer (1)/adhesive layer (1)/first liquid crystal retardation layer (1)/first base layer (1) was obtained.

<Preparation of first liquid crystal retardation layer (2)>
(Preparation of photo-alignment film-forming composition (2) (alignment layer-forming composition))
The photo-alignment material (weight average molecular weight: 50,000, m:n = 50:50) having the following structure was produced according to the method described in JP 2021-196514 A. A photo-alignment film-forming composition (2) was prepared by mixing 2 parts of the photo-alignment material and 98 parts of cyclopentanone (solvent) as components and stirring the resulting mixture at 80 ° C. for 1 hour.
Photo-alignable materials:

(Preparation of first liquid crystal retardation layer forming composition (2))
Polymerizable liquid crystal compound (A3) and polymerizable liquid crystal compound (A4) having the structures shown below were prepared. Polymerizable liquid crystal compound (A3) was prepared in the same manner as described in JP-A-2019-003177. Polymerizable liquid crystal compound (A4) was prepared in the same manner as described in JP-A-2009-173893.

重合性液晶化合物（Ａ４）：

Polymerizable liquid crystal compound (A3):

Polymerizable liquid crystal compound (A4):

A solution was obtained by dissolving 1 mg of polymerizable liquid crystal compound (A3) in 10 mL of chloroform. The obtained solution was placed in a measurement cell with an optical path length of 1 cm, and the measurement sample was placed in an ultraviolet-visible spectrophotometer (Shimadzu Corporation, "UV-2450") to measure the absorption spectrum. The wavelength at which the maximum absorbance was obtained was read from the obtained absorption spectrum, and the maximum absorption wavelength λmax in the wavelength range of 300 to 400 nm was 356 nm.

The polymerizable liquid crystal compound (A3) and the polymerizable liquid crystal compound (A4) were mixed in a mass ratio of 90:10 to obtain a mixture. 0.1 parts of a leveling agent "BYK-361N" (manufactured by BM Chemie) and 3 parts of a photopolymerization initiator "Irgacure OXE-03" (manufactured by BASF Japan Ltd.) were added to 100 parts of the obtained mixture. Furthermore, N-methyl-2-pyrrolidone (NMP) was added so that the solid content concentration was 13%. This was stirred at a temperature of 80°C for 1 hour to prepare a first liquid crystal retardation layer forming composition (2).

(Preparation of the first liquid crystal retardation layer (2) with substrate)
The photo-alignment film-forming composition (2) was applied to a biaxially oriented polyethylene terephthalate (PET) film (Diafoil, manufactured by Mitsubishi Plastics, Inc.) as the first base layer (2) using a bar coater. The resulting coating layer was dried at 120°C for 2 minutes and then cooled to room temperature to form a dry coating. Thereafter, a UV irradiation device (SPOT CURE SP-9; manufactured by Ushio Inc.) was used to irradiate 100 mJ of polarized ultraviolet light (based on 313 nm) to obtain a photo-alignment film as the first alignment layer (2). The thickness of the first alignment layer (2) measured using an ellipsometer M-220 manufactured by JASCO Corporation was 100 nm.

On the first alignment layer (2), the first liquid crystal retardation layer forming composition (2) was applied by a bar coater to form a first coating layer (2). This first coating layer (2) was dried by heating at 120° C. for 2 minutes, and then cooled to room temperature to obtain a first coating layer (2) with a substrate. Next, using a high-pressure mercury lamp ("Uniqure VB-15201BY-A" manufactured by Ushio Inc.), the first substrate layer (2) side of the substrate-attached first coating layer ( ² ) was irradiated with ultraviolet light having an integrated light quantity of 500 mJ/cm ² (based on 365 nm) under a nitrogen atmosphere, and the first substrate layer (2) side of the substrate-attached first coating layer (2) was irradiated with ultraviolet light having an integrated light quantity of 300 J/cm 2 (based on 365 nm). This formed a first polymer layer (2) (horizontally aligned liquid crystal cured film) in which the polymerizable liquid crystal compound was cured in a state where it was aligned horizontally relative to the plane of the first substrate layer (2), thereby obtaining a substrate-attached first liquid crystal retardation layer (2) consisting of the first substrate layer (2)/first liquid crystal retardation layer (2) (first alignment layer (2)/first polymer layer (2)). The thickness of the first polymer layer (2) was measured using a laser microscope LEXT OLS4100 manufactured by Olympus Corporation and was found to be 2.0 μm.

The first liquid crystal retardation layer (2) side of the substrate-attached first liquid crystal retardation layer (2) was subjected to a corona treatment, and the substrate-attached first liquid crystal retardation layer (2) was attached to glass via a 25 μm pressure-sensitive adhesive manufactured by Lintec Corporation, and the first substrate layer (2) was peeled off and removed. The in-plane retardation value was measured using a KOBRA-WR manufactured by Oji Scientific Instruments Co., Ltd. The in-plane retardation values for light with wavelengths of 450 nm, 550 nm, and 650 nm were calculated from Cauchy's dispersion formula obtained from the measurement results of the in-plane retardation values for light with wavelengths of 448.2 nm, 498.6 nm, 548.4 nm, 587.3 nm, 628.7 nm, and 748.6 nm.

As a result, the in-plane retardation values of the first liquid crystal retardation layer (2) were Re(450)=122 nm, Re(550)=140 nm, and Re(650)=144 nm, and the relationship of the in-plane retardation values at each wavelength was as follows.
Re(450)/Re(550)=0.87
Re(650)/Re(550)=1.03
[In the formula, Re(450) represents an in-plane retardation value for light having a wavelength of 450 nm, Re(550) represents an in-plane retardation value for light having a wavelength of 550 nm, and Re(650) represents an in-plane retardation value for light having a wavelength of 650 nm.]

According to the procedure for measuring the surface hardness of the first liquid crystal retardation layer described above, the surface hardness (H1) of the first surface and the surface hardness (H2) of the second surface of the first liquid crystal retardation layer (2) were measured. In the measurement, the surface of the first liquid crystal retardation layer (2) opposite the first base layer (2) was defined as the first surface, and the surface of the first liquid crystal retardation layer (2) on the first base layer (2) side was defined as the second surface. The results are shown in Tables 1 and 2.

<Preparation of First Liquid Crystal Retardation Layer (c1) and Retardation Body (c1)>
(Preparation of the first liquid crystal retardation layer (c1) with substrate)
Instead of irradiating both sides of the substrate-attached first coating layer (1) with ultraviolet light, the substrate-attached first coating layer (1) was irradiated only from the first coating layer (1) side of the substrate-attached first coating layer (1) with ultraviolet light with an integrated light amount of 1000 mJ/cm ² (based on 365 nm), except that the substrate-attached first liquid crystal retardation layer (c1) was obtained in the same manner as in the preparation of the substrate-attached first liquid crystal retardation layer (1). The substrate-attached first liquid crystal retardation layer (c1) has a layer structure of the first substrate layer (1)/first liquid crystal retardation layer (c1) (first alignment layer (1)/first polymer layer (c1)). According to the above-mentioned procedure for measuring the surface hardness of the first liquid crystal retardation layer, the surface hardness of the first surface (H1) and the surface hardness of the second surface (H2) were measured (H1/H2). The results are shown in Table 2.

(Preparation of Retardation Body (c1))
A retarder (c1) was obtained in the same manner as in the preparation of the retarder (1), except that the first liquid crystal retarder layer (c1) with a substrate was used instead of the first liquid crystal retarder layer (1) with a substrate. The retarder (c1) has a layer structure of the second substrate layer (1)/the second liquid crystal retarder layer (1)/the adhesive layer (1)/the first liquid crystal retarder layer (c1)/the first substrate layer (1).

<Preparation of first liquid crystal retardation layer (c2)>
Instead of irradiating both sides of the substrate-attached first coating layer (2) with ultraviolet light, the substrate-attached first coating layer (2) was irradiated only from the first coating layer (2) side of the substrate-attached first coating layer (2) with ultraviolet light with an integrated light amount of 500 mJ/cm ² (based on 365 nm), except that the substrate-attached first liquid crystal retardation layer (c2) was obtained by the same procedure as for preparing the substrate-attached first liquid crystal retardation layer (2). The substrate-attached first liquid crystal retardation layer (c2) has a layer structure of the first substrate layer (2)/first liquid crystal retardation layer (c2) (first alignment layer (2)/first polymer layer (c2)). According to the procedure for measuring the surface hardness of the first liquid crystal retardation layer described above, the surface hardness of the first liquid crystal retardation layer (c2) was measured, and the ratio (H1/H2) of the surface hardness (H1) of the first surface to the surface hardness (H2) of the second surface was calculated. The results are shown in Tables 1 and 2.

<Preparation of Adhesive Layer>
(Preparation of acrylic resin solution (1))
A reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer was charged with a mixed solution of 81.8 parts of ethyl acetate, 90.0 parts of butyl acrylate, 5.0 parts of methyl acrylate, and 5.0 parts of acrylic acid, and the air in the apparatus was replaced with nitrogen gas to make it oxygen-free, while raising the internal temperature to 55 ° C. Then, a solution of 0.15 parts of azobisisobutyronitrile (polymerization initiator) dissolved in 10 parts of ethyl acetate was added in its entirety. After the polymerization initiator was added, the temperature was maintained for 1 hour, and then ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts/hr while maintaining the internal temperature at 54 to 56 ° C., and the addition of ethyl acetate was stopped when the concentration of the (meth)acrylic resin became 35% by mass, and the temperature was maintained until 6 hours had elapsed from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the (meth)acrylic resin to 20% by mass, and an acrylic resin solution (1) was prepared. The resulting (meth)acrylic resin had a weight average molecular weight Mw of 1.6 million and a molecular weight distribution Mw/Mn of 4.5. Mw and Mn were measured in terms of standard polystyrene using two "TSKgel GMHHR-H(S)" columns manufactured by Tosoh Corporation connected in series as columns in a GPC apparatus, tetrahydrofuran as an eluent, a sample concentration of 2 mg/mL, a sample introduction amount of 100 μL, a temperature of 40° C., and a flow rate of 1 mL/min.

(Preparation of Pressure-Sensitive Adhesive Composition (1))
To 100 parts of the solid content of the acrylic resin solution (1), 0.15 parts on an active ingredient basis of a crosslinking agent (manufactured by Tosoh Corporation: product name "Coronate L" (a solution of a trimethylolpropane adduct of tolylene diisocyanate in ethyl acetate (solid content concentration 75% by mass)) and 0.2 parts of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.: product name "KBM-403") were added, and ethyl acetate was further added so that the solid content concentration became 13%, thereby obtaining a pressure-sensitive adhesive composition (1).

(Preparation of Pressure-Sensitive Adhesive Layer (1) and Pressure-Sensitive Adhesive Sheet (1))
The pressure-sensitive adhesive composition (1) was applied to the release-treated surface of a separator made of a release-treated polyethylene terephthalate film ("PLR-382190" available from Lintec Corporation) using an applicator so that the thickness after drying would be 17 μm, and the applied layer was dried at 100° C. for 1 minute to prepare a pressure-sensitive adhesive layer. Next, the surface of the resulting pressure-sensitive adhesive layer opposite the separator film was attached to the release-treated surface of a separator made of a release-treated polyethylene terephthalate film ("PET-251130" available from Lintec Corporation) to form a pressure-sensitive adhesive layer (1), and a pressure-sensitive adhesive sheet (1) having a layer structure of separator/pressure-sensitive adhesive layer (1)/separator was prepared.

The shear storage modulus of the adhesive layer (1) at 23°C was measured using the procedure described below and was found to be 0.026 MPa.

(Preparation of acrylic resin solution (2))
A reaction vessel equipped with a cooling tube, a nitrogen inlet tube, a thermometer, and a stirrer was charged with a mixed solution of 100 parts of ethyl acetate, 99.0 parts of butyl acrylate, 0.5 parts of 2-hydroxyethyl acrylate, and 0.5 parts of acrylic acid, and the internal temperature was raised to 55 ° C. while replacing the air in the apparatus with nitrogen gas to make it oxygen-free. Then, the entire amount of a solution in which 0.12 parts of azobisisobutyronitrile (polymerization initiator) was dissolved in 10 parts of ethyl acetate was added. After the addition of the polymerization initiator, the temperature was maintained for 1 hour, and then ethyl acetate was continuously added to the reaction vessel at an addition rate of 17.3 parts/hr while maintaining the internal temperature at 54 to 56 ° C., and the addition of ethyl acetate was stopped when the concentration of the (meth)acrylic resin became 35% by mass, and the temperature was maintained until 6 hours had elapsed from the start of the addition of ethyl acetate. Finally, ethyl acetate was added to adjust the concentration of the (meth)acrylic resin to 20% by mass, and an acrylic resin solution (2) was prepared. The resulting (meth)acrylic resin had a weight average molecular weight Mw of 1.7 million and a molecular weight distribution Mw/Mn of 3.9. Mw and Mn were measured in terms of standard polystyrene using two "TSKgel GMHHR-H(S)" columns manufactured by Tosoh Corporation connected in series as columns in a GPC apparatus, tetrahydrofuran as an eluent, a sample concentration of 2 mg/mL, a sample introduction amount of 100 μL, a temperature of 40° C., and a flow rate of 1 mL/min.

(Preparation of Pressure-Sensitive Adhesive Composition (2))
To 80 parts of the solid content of the acrylic resin solution (2), 20 parts (solid content) of a bifunctional acrylate having the structure shown below (obtained from Shin-Nakamura Chemical Co., Ltd.; product number "A-DOG"), 2.5 parts of a crosslinking agent (manufactured by Tosoh Corporation: product name "Coronate L" (ethyl acetate solution of trimethylolpropane adduct of tolylene diisocyanate (solid content concentration 75% by mass)) based on active ingredient, 1.5 parts of a photopolymerization initiator (manufactured by Ciba Specialty Chemicals: product name "Irgacure 500"), and 0.3 parts of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.: product name "KBM-403") were added, and ethyl acetate was further added so that the solid content concentration became 13%, to obtain a pressure-sensitive adhesive composition (2).

Bifunctional acrylate "A-DOG":

(Preparation of Pressure-Sensitive Adhesive Layer (2) and Pressure-Sensitive Adhesive Sheet (2))
The adhesive composition (2) was applied to the release-treated surface of a separator made of a release-treated polyethylene terephthalate film ("PLZ-383030" available from Lintec Corporation) using an applicator so that the thickness after drying would be 5 μm, and the coating was dried at 100° C. for 1 minute to prepare an adhesive layer. Next, the surface of the resulting adhesive layer opposite the separator was attached to the release-treated surface of a separator made of a release-treated polyethylene terephthalate film ("PLR-381031" available from Lintec Corporation). Subsequently, an adhesive layer (2) was formed by irradiating with ultraviolet light under the following conditions, and an adhesive sheet (2) having a layer structure of separator/adhesive layer (2)/separator was prepared.
[UV irradiation conditions]
Fusion UV lamp system (manufactured by Fusion UV Systems) H bulb used. Accumulated light amount in UV wavelength region UVA: 250 mJ/cm ² (measurement device: measured value using UV Power Puck II manufactured by Fusion UV).

The shear storage modulus of the adhesive layer (2) at 23°C was measured using the procedure described below and was found to be 0.13 MPa.

(Preparation of Pressure-Sensitive Adhesive Layer (3) and Pressure-Sensitive Adhesive Sheet (3))
An adhesive sheet (3) having a layer structure of separator/adhesive layer (3)/separator was prepared in the same manner as in the preparation of adhesive sheet (2), except that the thickness of the adhesive layer was 10 μm.

The shear storage modulus of the adhesive layer (3) at 23°C was measured using the procedure described below and was found to be 0.13 MPa.

[Thickness Measurement]
The thickness of the adhesive layer was measured using a contact type film thickness meter (Nikon: Digimicro MH-15M). The results are shown in Tables 1 and 2.

[Measurement of shear storage modulus]
The shear storage modulus of the adhesive layer was measured using a viscoelasticity measuring device (MCR-301, Anton Paar). The same adhesive layer as used in the examples and comparative examples was cut to a width of 30 mm x length of 30 mm, the separator was peeled off, and a plurality of sheets were laminated to a thickness of 200 μm and bonded to a measurement stage. After that, in a state where it was attached to a measurement chip (PP25, Anton Paar), measurement was performed in a temperature range of −20° C. to 100° C. under conditions of a frequency of 1.0 Hz, a deformation amount of 1%, a normal force of 1 N, and a temperature rise rate of 5° C./min.

[Measurement of indentation elastic modulus]
The adhesive layer was attached to glass to prepare a measurement sample. Using an ultra-microhardness tester (FISCHERSCOPE HM2000: manufactured by Fischer Instruments Co., Ltd.), a Vickers indenter was used to apply a load to the adhesive layer side of the measurement sample at a pressure rate of 0.1 mN/10 seconds, and then the load was maintained for 5 seconds to read the indentation modulus E _IT [MPa], which was defined as the indentation elastic modulus [MPa]. The measurement was performed at a temperature of 23°C. The results are shown in Tables 1 and 2.

Example 1
The TAC film side of the polarizing plate a was subjected to a corona treatment, and the surface of the adhesive sheet (1) from which one separator had been peeled off was attached, and then the other separator was peeled off to expose the adhesive layer (1). The second liquid crystal retardation layer (1) exposed by peeling off the second base material layer (1) of the retarder (1) was subjected to a corona treatment, and the retardation layer (1) was attached to the above-exposed adhesive layer (1), and the first base material layer (1) was peeled off to obtain an optical laminate (1). The second alignment layer (1) was peeled off together with the second base material layer (1), and the first alignment layer (1) was peeled off together with the first base material layer (1). The layer structure of the optical laminate (1) was polarizing plate a/adhesive layer (1)/second liquid crystal retardation layer (1)/adhesive layer (1)/first liquid crystal retardation layer (1).

Example 2
Except for using the polarizing plate b instead of the polarizing plate a, an optical laminate (2) was produced in the same manner as in Example 1. The layer structure of the optical laminate (2) was polarizing plate b/adhesive layer (1)/second liquid crystal retardation layer (1)/adhesive layer (1)/first liquid crystal retardation layer (1).

Example 3
The TAC film side of the polarizing plate a was subjected to corona treatment, and the surface of the adhesive sheet (2) from which one separator had been peeled was attached, and then the other separator was peeled off to expose the adhesive layer (2). The first liquid crystal retardation layer (2) side of the substrate-attached first liquid crystal retardation layer (2) was subjected to corona treatment, and the substrate-attached first liquid crystal retardation layer (2) was attached to the exposed adhesive layer (2), and then the first base layer (2) was peeled off to obtain an optical laminate (3). The first alignment layer (2) was also peeled off together with the first base layer (2). The layer structure of the optical laminate (3) was polarizing plate a/adhesive layer (2)/first liquid crystal retardation layer (2).

Example 4
Except for using the polarizing plate b instead of the polarizing plate a, an optical laminate (4) was produced in the same manner as in Example 3. The layer structure of the optical laminate (4) was polarizing plate b/adhesive layer (2)/first liquid crystal retardation layer (2).

Example 5
Except for using the adhesive sheet (2) instead of the adhesive sheet (1), an optical laminate (5) was produced in the same manner as in Example 1. The layer structure of the optical laminate (5) was polarizing plate a/adhesive layer (2)/second liquid crystal retardation layer (1)/adhesive layer (1)/first liquid crystal retardation layer (1).

Example 6
An optical laminate (6) was produced in the same manner as in Example 5, except that the polarizing plate b was used instead of the polarizing plate a. The layer structure of the optical laminate (6) was polarizing plate b/adhesive layer (2)/second liquid crystal retardation layer (1)/adhesive layer (1)/first liquid crystal retardation layer (1).

Example 7
Except for using the pressure-sensitive adhesive sheet (3) instead of the pressure-sensitive adhesive sheet (2), an optical laminate (7) was produced in the same manner as in Example 3. The layer structure of the optical laminate (7) was polarizing plate a/pressure-sensitive adhesive layer (3)/first liquid crystal retardation layer (2).

Example 8
An optical laminate (8) was produced in the same manner as in Example 7, except that the polarizing plate b was used instead of the polarizing plate a. The layer structure of the optical laminate (8) was polarizing plate b/adhesive layer (3)/first liquid crystal retardation layer (2).

Example 9
Except for using the adhesive sheet (3) instead of the adhesive sheet (1), an optical laminate (9) was produced in the same manner as in Example 1. The layer structure of the optical laminate (9) was polarizing plate a/adhesive layer (3)/second liquid crystal retardation layer (1)/adhesive layer (1)/first liquid crystal retardation layer (1).

Example 10
An optical laminate (10) was produced in the same manner as in Example 9, except that polarizing plate b was used instead of polarizing plate a. The layer structure of the optical laminate (10) was polarizing plate b/adhesive layer (3)/second liquid crystal retardation layer (1)/adhesive layer (1)/first liquid crystal retardation layer (1).

Comparative Example 1
The TAC film side of the polarizing plate a was subjected to corona treatment, and the surface of the pressure-sensitive adhesive sheet (1) from which one separator had been peeled off was attached, and then the other separator was peeled off to expose the pressure-sensitive adhesive layer (1). The second substrate layer (1) and the second alignment layer (1) of the retarder (c1) were peeled off to expose the second liquid crystal retardation layer (1), and the second liquid crystal retardation layer (1) was subjected to corona treatment, and the retarder was attached to the above-exposed pressure-sensitive adhesive layer (1), and then the first substrate layer (1) and the first alignment layer (1) were peeled off to obtain an optical laminate (c1). The layer structure of the optical laminate (c1) was polarizing plate a/adhesive layer (1)/second liquid crystal retardation layer (1)/adhesive layer (1)/first liquid crystal retardation layer (c1).

Comparative Example 2
The TAC film side of the polarizing plate a was subjected to corona treatment, and the surface of the adhesive sheet (1) from which one separator had been peeled was attached, and then the other separator was peeled off to expose the adhesive layer (1). The exposed adhesive layer (1) was attached to the first liquid crystal retardation layer (c2) of the substrate-attached first liquid crystal retardation layer (c2), and then the first base layer (2) was peeled off to obtain an optical laminate (c2). The first alignment layer (2) was also peeled off together with the first base layer (2). The layer structure of the optical laminate (c2) was polarizing plate a/adhesive layer (1)/first liquid crystal retardation layer (c2).

[Heat shock test]
The polarizing plate side of the optical laminate obtained in the examples and comparative examples was attached to a glass plate via an adhesive layer to prepare an evaluation sample. The tip of an Erichsen pen (manufactured by Erichsen, model number 318) set to a load of 10 N was pressed against the surface of the first liquid crystal retardation layer side of the optical laminate to prepare a starting point for this evaluation sample. Four more starting points were provided at equal intervals from the starting point (a total of five starting points were provided). The evaluation sample provided with five starting points was placed in a thermostatic chamber, and a heat cycle in which the sample was held at a temperature of -40°C for 30 minutes and then held at a temperature of 85°C for 30 minutes was considered as one cycle, and a heat shock test was performed in which this heat cycle was repeated 200 times. For the evaluation sample after the heat shock test, the length of the cracks (cracks) generated from the five starting points provided before the heat shock test was measured. The average value of the length of the cracks generated from the five starting points was taken as the crack length of each optical laminate, and was evaluated according to the following criteria. The results are shown in Tables 1 and 2.
A: The crack length is 1 mm or less.
B: The crack length is more than 1 mm and 3 mm or less.
C: The crack length is more than 3 mm and 5 mm or less.
D: The crack length is more than 5 mm and 10 mm or less.
E: The crack length exceeds 10 mm.

1, 2 optical laminate, 3, 4 optical laminate with base material, 11 first liquid crystal retardation layer, 12 first coating layer with base material (coating layer with base material), 13 first liquid crystal retardation layer with base material layer, 16 first base material layer, 17 first alignment layer, 18 first coating layer (coating layer), 21 second liquid crystal retardation layer, 22 second coating layer with base material, 23 second liquid crystal alignment layer with base material Retardation layer, 26 Second base material layer, 27 Second alignment layer, 28 Second coating layer, 31 First adhesive layer (adhesive layer), 32 Second adhesive layer, 50 Polarizing plate .

Claims (12)

An optical laminate including a polarizing plate including a polarizing element, a pressure-sensitive adhesive layer, a second liquid crystal retardation layer, a first liquid crystal retardation layer, and a base layer in this order,
The first liquid crystal retardation layer is a first polymer layer containing a polymer of a polymerizable liquid crystal compound, or a multilayer body of the first polymer layer and a first alignment layer,
a ratio (H1/H2) of a surface hardness (H1) of a first surface of the first liquid crystal retardation layer to a surface hardness (H2) of a second surface of the first liquid crystal retardation layer opposite to the first surface is 0.90 or more and 1.10 or less;
the substrate layer is a film substrate made of a resin selected from the group consisting of a cyclic olefin resin and triacetyl cellulose;
The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer,
The product of the indentation elastic modulus of the adhesive layer at a temperature of 23° C. and the thickness of the adhesive layer is 300 MPa·μm or more . The optical laminate according to claim 1 , wherein the first liquid crystal retardation layer is the first polymer layer. The optical laminate according to claim 1 or 2, wherein the polarizing element is a polarizer containing a polyvinyl alcohol resin and boron. The optical laminate according to claim 1 or 2, wherein the first liquid crystal retardation layer is a 1/2 liquid crystal retardation layer or a 1/4 liquid crystal retardation layer. The optical laminate according to claim 1 or 2, wherein the second liquid crystal retardation layer is a second polymer layer containing a polymer of a polymerizable liquid crystal compound, or a multilayer body of the second polymer layer and a second alignment layer. 3. The optical laminate according to claim 1, wherein the laminate of the first liquid crystal retardation layer and the second liquid crystal retardation layer satisfies the relationship of the following formulas (1)' and (2)'.
100≦Re(550)≦180 (1)'
Re(450)/Re(550)≦1.00 (2)'
[In formula (1)′ and formula (2)′,
Re(450) represents an in-plane retardation value for light having a wavelength of 450 nm;
Re(550) represents an in-plane retardation value for light having a wavelength of 550 nm.] The optical laminate according to claim 1 or 2, wherein the polarizing plate has a polarizing element protective film on one or both sides of the polarizing element. The optical laminate according to claim 1 or 2, wherein the base layer is in direct contact with the first liquid crystal retardation layer. A method for producing an optical laminate including a polarizing plate including a polarizing element, a pressure-sensitive adhesive layer, a second liquid crystal retardation layer, and a first liquid crystal retardation layer in this order,
The first liquid crystal retardation layer is a first polymer layer containing a polymer of a polymerizable liquid crystal compound, or a multilayer body of the first polymer layer and a first alignment layer,
a ratio (H1/H2) of a surface hardness (H1) of a first surface of the first liquid crystal retardation layer to a surface hardness (H2) of a second surface of the first liquid crystal retardation layer opposite to the first surface is 0.90 or more and 1.10 or less;
The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer,
The product of the indentation elastic modulus of the adhesive layer at a temperature of 23° C. and the thickness of the adhesive layer is 300 MPa μm or more,
The manufacturing method includes:
A step (S1) of obtaining a substrate-attached coating layer having the substrate layer and the coating layer by applying a liquid crystal retardation layer forming composition containing a polymerizable liquid crystal compound onto the substrate layer or onto the first alignment layer formed on the substrate layer;
and (S2) irradiating both surfaces of the substrate-attached coating layer with active energy rays to polymerize the polymerizable liquid crystal compound in the coating layer to form the first polymer layer,
The method for producing an optical laminate, wherein the substrate layer is a film substrate made of a resin selected from the group consisting of cyclic olefin resins and triacetyl cellulose. The active energy ray is ultraviolet light,
The method for producing an optical laminate according to claim 9 , wherein a total integrated light amount of the active energy rays irradiated to both sides of the substrate-attached coating layer in the step (S2) is 10 mJ/cm ² or more and 3000 mJ/cm ² or less. Further, a step of obtaining an optical laminate with a substrate, the optical laminate including the polarizing plate, the pressure-sensitive adhesive layer, the first liquid crystal retardation layer, and the substrate layer in this order;
The method for producing the optical laminate according to claim 9 or 10 , further comprising a step of peeling off the base layer from the substrate-attached optical laminate. The substrate-attached optical laminate further includes the second liquid crystal retardation layer between the pressure-sensitive adhesive layer and the first liquid crystal retardation layer,
The method for producing an optical laminate according to claim 11 , wherein the second liquid crystal retardation layer is a second polymer layer containing a polymer of a polymerizable liquid crystal compound, or a multilayer body of the second polymer layer and a second alignment layer.

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