JP2023107668A - optical adhesive sheet - Google Patents

Abstract

To provide an optical adhesive sheet which suppresses surrounding contamination, improves handling performance and excels in adhesive reliability.SOLUTION: There is provided an optical adhesive sheet 1 which comprises a release liner 2 and an adhesive layer 3 in order toward one side in the thickness direction. The maximum length L of the adhesive layer 3 in the orthogonal direction orthogonal to the thickness direction is 200 mm or more. The release liner 2 is larger than the adhesive layer 3 and encloses the adhesive layer 3 when viewed in the thickness direction.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an optical pressure-sensitive adhesive sheet, and more particularly to an optical pressure-sensitive adhesive sheet that is suitably used for adhering a member for an image display device.

An optical adhesive sheet is known that includes a release liner, an adhesive layer, and a second release liner in this order (see, for example, Patent Document 1 below).

In the optical pressure-sensitive adhesive sheet described in Patent Document 1, the release liner is peeled off from the pressure-sensitive adhesive layer, and then the pressure-sensitive adhesive layer is attached to the member of the image display device. Image display devices include tablets.

Japanese Patent Application Laid-Open No. 2020-122140

However, when the adhesive layer described above is attached to a member of a tablet, the size of the adhesive layer is also large because the size of the tablet is large. Then, the size of the optical adhesive sheet provided with the adhesive layer also increases. Then, it is necessary to transport the optical adhesive sheet by machine.

Here, when the adhesive layer has the same size as the release liner and the second release liner, the edges of the adhesive layer tend to protrude outward from the release liner and the second release liner. Then, there is a problem that the pressure-sensitive adhesive composition of the pressure-sensitive adhesive layer contaminates the machine.

Moreover, when the above-described protrusion occurs, the end portion of the optical adhesive sheet unintentionally sticks to the machine, resulting in a problem that the handleability of the optical adhesive sheet is deteriorated.

Furthermore, if the above-described protrusion occurs, the adhesive layer will have a defect at the end, resulting in a lack of the adhesive. Then, the adhesive reliability of the adhesive layer is lowered.

The present invention provides an optical pressure-sensitive adhesive sheet that suppresses contamination of the surroundings, improves handleability, and has excellent adhesion reliability.

In the present invention (1), a release liner and an adhesive layer are provided in order toward one side in the thickness direction, and the maximum length L of the adhesive layer in a direction orthogonal to the thickness direction is 200 mm or more. The release liner includes an optical adhesive sheet that is larger than the adhesive layer and includes the adhesive layer when viewed in the thickness direction.

In this optical adhesive sheet, since the maximum length L of the adhesive layer is 200 mm or more, the adhesive layer can be attached to a member of a large image display device such as a tablet.

Further, even if the length L is 200 mm or more, in the optical adhesive sheet of the present invention, the release liner is larger than the adhesive layer when viewed in the thickness direction and includes the adhesive layer. suppresses the edge of the adhesive layer from protruding. Therefore, contamination of the surroundings by the adhesive layer can be suppressed.

Furthermore, in this optical pressure-sensitive adhesive sheet, protrusion of the end portion of the pressure-sensitive adhesive layer is suppressed, so that the handleability is excellent.

Furthermore, in this optical adhesive sheet, since the protrusion of the end portion of the adhesive layer is suppressed, chipping of the adhesive is suppressed, and the adhesion reliability of the adhesive layer is excellent.

The present invention (2) includes the optical pressure-sensitive adhesive sheet according to (1), wherein the deflection amount D measured in the following deflection test is 7 mm or less.

Flexure test: The optical pressure-sensitive adhesive sheet is shaped to a size of 100 mm in length and 25 mm in width to prepare a sample. A table having a top surface and a height of 50 mm or more is prepared. A surface of a first portion having a length of 50 mm including one longitudinal edge of the sample is fixed to the upper surface, and a second portion having a length of 50 mm including the other longitudinal edge of the sample is attached to one edge of the upper surface. protrude laterally from the After that, it is left at 23° C. for 5 minutes. After that, the amount of movement of the protruding edge of the sample downward from the upper surface is obtained. Separately, the rear surface of the first portion is fixed to the upper surface, and the movement amount is obtained. An average value of the two amounts of movement is obtained as the amount of deflection D.

Since this optical adhesive sheet has a bending amount D of 7 mm or less, the optical adhesive sheet is even more excellent in handleability.

In the present invention (3), the area P, which is the product of the offset amount of the release liner defined below and the thickness of the release liner, is 90×10 ⁻⁸ m ² or more, (1) or (2) ) includes the optical adhesive sheet described in .

Offset amount: length (mm) of the offset portion of the release liner that is displaced from the adhesive layer when viewed in the thickness direction
The thickness: the average thickness (μm) at three points in the offset portion

In this optical adhesive sheet, since the area P is 90×10 ⁻⁸ m ² or more, it is possible to prevent the adhesive layer from lifting from the release liner.

The present invention (4) further comprises an adjacent layer adjacent to the adhesive layer on the opposite side of the release liner in the thickness direction, wherein the release liner, the adhesive layer, and the adjacent layer are the following [1]: The optical pressure-sensitive adhesive sheet according to (2), which satisfies the formula, is included.

E1×E2×(T1+T2)/[T0 ^1/2 ×100,000]≧2,500
[1]

E1: Tensile modulus (MPa) of the release liner at 23°C
E2: Tensile modulus (MPa) of the adjacent layer at 23°C
T1: Thickness of the release liner (μm)
T2: thickness of the adjacent layer (μm)
T0: Thickness of the adhesive layer (μm)

When the above formula [1] is satisfied, it is selected from the group consisting of the thickness T1 of the release liner, the tensile modulus E1 of the release liner, the thickness T2 of the adjacent layer, and the tensile modulus E2 of the adjacent layer. at least one of the Therefore, even if the pressure-sensitive adhesive layer is thick, the release liner and/or the adjacent layers tend to harden, so that the amount of deflection D of the optical pressure-sensitive adhesive sheet can be reduced.

Alternatively, when the above formula [1] is satisfied, the adhesive layer is thin. Therefore, even if at least one selected from the group consisting of the thickness T1 of the release liner, the tensile modulus E1 of the release liner, the thickness T2 of the adjacent layer, and the tensile modulus E2 of the adjacent layer is small, Since the optical pressure-sensitive adhesive sheet can ensure toughness, the amount of deflection D of the optical pressure-sensitive adhesive sheet can be reduced.

The present invention (5) includes the optical pressure-sensitive adhesive sheet according to (4), wherein the adjacent layer is a second release liner.

The present invention (6) includes the optical adhesive sheet according to (5), wherein the second release liner is larger than the adhesive layer when viewed in the thickness direction and includes the adhesive layer.

In this optical pressure-sensitive adhesive sheet, the second release liner is larger than the pressure-sensitive adhesive layer when viewed in the thickness direction and includes the pressure-sensitive adhesive layer. and is even more excellent in handleability.

In the present invention (7), the area P2, which is the product of the second offset amount of the second release liner defined below and the thickness of the second release liner, is 90×10 ⁻⁸ m ² or more. (6) includes the optical pressure-sensitive adhesive sheet.

Offset amount: Length (mm) of the second offset portion of the second release liner that is displaced from the adhesive layer when viewed in the thickness direction
Thickness: average thickness (μm) at three points in the second offset portion

In this optical adhesive sheet, since the area P2 is 90×10 ⁻⁸ m ² or more, it is possible to prevent the adhesive layer from lifting from the second release liner.

The present invention (8) includes the optical pressure-sensitive adhesive sheet according to (4), wherein the adjacent layer is a member for an image display device.

The present invention (9) includes the optical adhesive sheet according to (8), wherein the peripheral edge of the image display device member matches the peripheral edge of the adhesive layer when viewed in the thickness direction. .

In the present invention (10), one surface of the release liner in the thickness direction is provided with a recess that is recessed toward the other side in the thickness direction around the peripheral edge of the adhesive layer, and the depth of the recess is The optical pressure-sensitive adhesive sheet according to any one of (1) to (9), which is 30 μm or less, is included.

The present invention (11) includes the optical adhesive sheet according to any one of (1) to (10), wherein the indentation hardness H of the adhesive layer at 23°C is 10 kPa or less.

In this optical adhesive sheet, since the indentation hardness H of the adhesive layer at 23° C. is 10 kPa or less, the adhesive layer is suitably used for attaching members in a repeatedly foldable image display device.

The present invention (12) includes the optical pressure-sensitive adhesive sheet according to any one of (1) to (11), wherein the pressure-sensitive adhesive layer has a shear storage modulus G' of 100 kPa or less at 25°C.

In this optical adhesive sheet, since the shear storage elastic modulus G′ of the adhesive layer at 25° C. is 100 kPa or less, the adhesive layer is suitable for attaching members in a repeatedly foldable image display device. Used.

The present invention (13) is an optical pressure-sensitive adhesive sheet provided with the pressure-sensitive adhesive layer provided in an image display device, wherein the pressure-sensitive adhesive layer and one surface and the other surface of the optical pressure-sensitive adhesive sheet in the thickness direction The optical pressure-sensitive adhesive sheet according to any one of (1) to (12), comprising a pair of image display device members formed respectively.

The optical pressure-sensitive adhesive sheet of the present invention suppresses contamination of the surroundings, improves handleability, and has excellent adhesion reliability.

1 is a cross-sectional view of an optical pressure-sensitive adhesive sheet according to one embodiment of the present disclosure; FIG. It is sectional drawing explaining the measurement of the bending amount of an optical adhesive sheet. 3A to 3D are process diagrams illustrating the method of manufacturing the optical adhesive sheet. FIG. 3A is a step of preparing a laminate. FIG. 3B is the step of contouring the adhesive layer and the third release liner. FIG. 3C is a process of removing unnecessary portions. FIG. 3D is the step of re-applying the third release liner to the adjacent layer and contouring the release liner. 1 is a cross-sectional view of an optical pressure-sensitive adhesive sheet having a member for an image display device as an adjacent layer; FIG. 1 is a cross-sectional view of an image display device; FIG. It is a sectional view of the optical adhesive sheet of a modification. It is another aspect of the optical adhesive sheet.

1. Optical adhesive sheet 1
One embodiment of the optical pressure-sensitive adhesive sheet of the present invention will be described with reference to FIG.

As shown in FIG. 1, the optical adhesive sheet 1 has a thickness. The optical adhesive sheet 1 is along the surface direction. The plane direction is an example of an orthogonal direction, and is orthogonal to the thickness direction. The shape of the optical adhesive sheet 1 when viewed from one side in the thickness direction is not particularly limited. Examples of the shape of the optical adhesive sheet 1 include a rectangular shape, an elliptical shape, and a circular shape.

The optical adhesive sheet 1 includes a release liner 2 and an adhesive layer 3 in order toward one side in the thickness direction. In this embodiment, the optical adhesive sheet 1 includes a release liner 2, an adhesive layer 3, and an adjacent layer 4 in order toward one side in the thickness direction.

1.2 Adhesive layer 3 and its size The adhesive layer 3 extends along the surface direction. The adhesive layer 3 has a sheet shape. Examples of the shape of the adhesive layer 3 when viewed from one side in the thickness direction include a rectangular shape, an elliptical shape, and a circular shape.

The maximum length L of the adhesive layer 3 in the plane direction is 200 mm or more.

If the adhesive layer 3 has a rectangular shape, the maximum length L of the adhesive layer 3 in the surface direction is the length of a line segment connecting two opposing corners. The maximum length L of the adhesive layer 3 in the plane direction is the length in the major axis direction if the shape of the adhesive layer 3 is elliptical. The maximum length L of the adhesive layer 3 in the surface direction is the diameter if the shape of the adhesive layer 3 is circular.

If the maximum length L of the adhesive layer 3 in the surface direction is less than 200 mm, the adhesive layer 3 cannot be attached to a member of a large image display device such as a tablet.

On the other hand, in the present invention, since the maximum length L of the adhesive layer 3 in the surface direction is 200 mm or more, the adhesive layer 3 can be attached to the members of the large-sized image display device described above.

The maximum length L of the adhesive layer 3 in the plane direction is preferably 200 mm or longer, more preferably 250 mm or longer, and still more preferably 300 mm or longer. The maximum length L of the adhesive layer 3 in the plane direction is, for example, 3000 mm or less, and is, for example, 2000 mm or less.

The thickness T0 of the adhesive layer 3 is, for example, 5 μm or more, preferably 10 μm or more, more preferably 30 μm or more, further preferably 40 μm or more, 50 μm or more, or 100 μm or more. Also, the thickness T0 of the adhesive layer 3 is, for example, 500 μm or less, preferably 150 μm or less, more preferably 100 μm or less, and further preferably 100 μm or less, 50 μm or less, or 30 μm or less.

1.3 Release Liner 2 and Its Size The release liner 2 forms the other side of the optical adhesive sheet 1 in the thickness direction. The release liner 2 is positioned at the other end of the optical adhesive sheet 1 in the thickness direction.
The release liner 2 is larger than the adhesive layer 3 when viewed in the thickness direction. The release liner 2 includes an adhesive layer 3 when viewed in the thickness direction. For example, the peripheral edge of the release liner 2 is exposed from the adhesive layer 3 . The release liner 2 has, for example, a shape similar to that of the adhesive layer 3 .

The length L1 of the release liner 2 in the first direction is, for example, 200 mm or more, preferably 201 mm or more, more preferably 203 mm or more, still more preferably 250 mm or more, and even more preferably 300 mm or more. The length L1 of the release liner 2 in the first direction is, for example, 3020 mm or less, and is, for example, 2020 mm or less. The first direction is a direction included in the surface direction, and is a direction that defines the maximum length L of the adhesive layer 3 described above.

The value (L1-L) obtained by subtracting the maximum length L of the adhesive layer 3 in the surface direction from the length L1 of the release liner 2 in the first direction is, for example, 1 mm or more, preferably 3 mm or more, and more preferably 5 mm. 10 mm or more, more preferably 10 mm or more. If the above value (L1−L) is at least the above lower limit, the effects of the optical adhesive sheet 1, such as suppression of contamination of the surroundings, improvement of handleability, and excellent adhesion reliability, can be achieved more reliably.

The upper limit of the value (L1-L) obtained by subtracting the maximum length L of the adhesive layer 3 in the planar direction from the length L1 of the release liner 2 in the first direction is, for example, 100 mm. If the above value (L1-L) is equal to or less than the above upper limit, it is possible to suppress deterioration in the handleability of the optical adhesive sheet 1 due to an excessively large offset portion 21 (described later) of the release liner 2.

The release liner 2 has an offset portion (margin portion) 21 according to the above value (L1-L). The offset portion 21 is the peripheral end portion along the outer periphery of the adhesive layer 3 in the release liner 2 .

The thickness T1 of the release liner 2 is appropriately set so that the area P, which will be described later, has a specific value, and the relational value with the tensile elastic modulus E1, which will be described later, has a specific value. The thickness T1 of the release liner 2 is, for example, 10 μm or more, preferably 30 μm or more, more preferably 50 μm or more, still more preferably 70 μm or more. The thickness T1 of the release liner 2 is, for example, 200 μm or less, preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less.

1.4 Adjacent Layer 4 and its Size In this embodiment, the adjacent layer 4 forms one surface of the optical adhesive sheet 1 in the thickness direction. The adjacent layer 4 is adjacent to the adhesive layer 3 on the opposite side of the release liner 2 in the thickness direction. The adjacent layer 4 is positioned at one end of the optical adhesive sheet 1 in the thickness direction.

As shown in FIG. 1, the peripheral edge of adjacent layer 4 coincides with the peripheral edge of release liner 2 when viewed through its thickness. Alternatively, as shown in FIG. 7, the adjacent layer 4 may be larger than and encompass the adhesive layer 3 when viewed in the thickness direction. A peripheral edge of the adjacent layer 4 is exposed from the adhesive layer 3 . In this case, the adjacent layer 4 has, for example, a shape similar to that of the adhesive layer 3 . The adjacent layer 4 is, for example, the second release liner 4A or the image display device member 11, and preferably the second release liner 4A in this embodiment.

The length L2 of the adjacent layer 4 in the first direction is, for example, 200 mm or longer, preferably 250 mm or longer, more preferably 300 mm or longer, still more preferably 500 mm or longer. The length L2 of the adjacent layer 4 in the first direction is, for example, 3000 mm or less, and is, for example, 2000 mm or less.

The value (L2-L) obtained by subtracting the maximum length L of the adhesive layer 3 in the surface direction from the length L2 of the adjacent layer 4 in the first direction is, for example, 0 mm or more, preferably 1 mm or more, preferably 3 mm or more. , more preferably 5 mm or more, still more preferably 10 mm or more.

As shown in FIG. 7, the upper limit of the value (L2-L) obtained by subtracting the maximum length L of the adhesive layer 3 in the planar direction from the length L2 of the adjacent layer 4 in the first direction is, for example, 100 mm. If the above value (L2-L) is equal to or less than the above upper limit, it is possible to suppress deterioration in the handleability of the optical adhesive sheet 1 due to the second offset portion 41 (described later) of the adjacent layer 4 becoming excessively large. .

1.5 Deflection amount D of optical adhesive sheet 1
The deflection amount D of the optical adhesive sheet 1 measured by the following deflection test is, for example, 20 mm or less, preferably 15 mm or less, more preferably 10 mm or less, still more preferably 7 mm or less, and particularly preferably 5 mm or less. be. The lower limit of the deflection amount D of the optical adhesive sheet 1 is 0 mm and 1 mm.

Flexure test: A sample 100 is produced by shaping the optical adhesive sheet 1 into a size of 100 mm in length and 25 mm in width. Sample 100 has neither offset portion 21 (described below) nor second offset portion 41 (described below). As shown in FIG. 2, a table 105 having an upper surface and a height of 50 mm or more is prepared. A first portion 101 with a length of 50 mm including one edge in the longitudinal direction of the sample 100 is fixed on the upper surface, and a second portion 102 with a length of 50 mm including the other edge in the longitudinal direction of the sample is fixed to the side from one edge of the upper surface. to protrude. A weight 106 is placed on the top surface of the first portion 101 . Thereby, the first portion 101 is fixed to the upper surface of the 106th. After that, it is left at 23° C. for 5 minutes. After that, one end edge of the projecting sample 100 acquires the amount of movement D that has moved downward from the upper surface. Separately, the rear surface of the first portion is fixed to the upper surface, and the amount of movement is obtained. An average value of the two amounts of movement is obtained as the amount of deflection D.

If the deflection amount D of the optical adhesive sheet 1 is equal to or less than the upper limit described above, the handleability of the optical adhesive sheet 1 is improved.

The deflection amount D is determined by the thickness T1 of the release liner 2, the tensile elastic modulus E1 of the release liner 2 (described later), the thickness T2 of the adjacent layer 4, the tensile elastic modulus E2 of the adjacent layer 4 (described later), and the adhesive layer 3. is adjusted by adjusting the shear storage modulus G′ (described later) of and the thickness T0 of the adhesive layer 3 . Furthermore, the deflection amount D can also be adjusted by adjusting the relational value (the left side of equations [1] to [8] described later), the area P (described later), and/or the area P2 (described later). be.

1.6 Physical Properties of Each Layer 1.6.1 Indentation Hardness H of Adhesive Layer 3
The indentation hardness H of the adhesive layer 3 at 23° C. is, for example, 20 kPa or less, preferably 10 kPa or less, more preferably 5 kPa or less, even more preferably 4 kPa or less, and particularly preferably 3 kPa or less. The lower limit of the indentation hardness H of the adhesive layer 3 at 23° C. is, for example, above 0.001 kP, preferably 0.01 kPa, more preferably 0.1 kPa. If the indentation hardness H of the adhesive layer 3 at 23° C. is equal to or less than the upper limit described above, the adhesive layer 3 is suitably used for attaching members in a repeatedly foldable image display device. The measurement of the indentation hardness H of the adhesive layer 3 will be described in later examples. The indentation hardness H of the adhesive layer 3 is adjusted by adjusting the formulation (kind) of the adhesive composition described below.

1.6.2 Shear storage modulus G' of adhesive layer 3
The shear storage modulus G′ of the adhesive layer 3 at 25° C. is, for example, 10 kPa or more, preferably 15 kPa or more, more preferably 20 kPa or more, still more preferably 25 kPa or more, and for example, 1000 kPa or less, preferably is 700 kPa or less, more preferably 500 kPa or less, still more preferably 300 kPa or less, and further preferably 200 kPa or less, 100 kPa or less, or 50 kPa or less. If the shear storage elastic modulus G' of the adhesive layer 3 is equal to or less than the upper limit described above, the adhesive layer 3 can achieve the softness required for use in flexible devices. The shear storage modulus G' of the adhesive layer 3 is determined by dynamic viscoelasticity measurement at a temperature increase rate of 5°C/min and a frequency of 1 Hz. The shear storage modulus G' of the adhesive layer 3 is adjusted by adjusting the formulation (kind) of the adhesive composition, which will be described later.

1.6.3 Area P, which is the product of the offset amount OL of the release liner 2 and the thickness T1
The area P (=OL×T1), which is the product of the offset amount OL of the release liner 2 and the thickness T1 of the release liner 2, is, for example, 50×10 ⁻⁸ m ² or more, preferably 90×10 ⁻⁸ m ^{2 .} 150×10 ⁻⁸ m ² or more, more preferably 200×10 ⁻⁸ m ² or more, and most preferably 300×10 ⁻⁸ m ² or more. The upper limit of the area P between the offset amount OL of the release liner 2 and the thickness T1 of the release liner 2 is, for example, 1,000×10 ⁻⁸ m ² , preferably 500×10 ⁻⁸ m ² .

The offset amount OL and thickness T1 of the release liner 2 are defined as follows.

Offset amount OL of release liner 2: Length (mm) of offset portion 21 of release liner 2 displaced from adhesive layer 3 when viewed in thickness direction
Thickness T1: average thickness (μm) at three points in the offset portion 21

There are two offset portions 21 in the first direction. Preferably, each of the offset amounts OL of the two offset portions 21 is the same.

The three points are co-located in the first direction and spaced apart from each other in the width direction in the offset portion 21 . The width direction is orthogonal to the thickness direction and the first direction.

When the area P is equal to or greater than the lower limit, the offset amount OL is large and/or thick.

When the offset amount OL of the release liner 2 is large, even if the offset portion 21 is deformed, such deformation hardly affects the adhesive layer 3 . Deformation includes folding of the offset portion 21 . Therefore, it is possible to prevent the adhesive layer 3 from unintentionally peeling off (floating) from the release liner 2 .

Alternatively, when the release liner 2 is thick, deformation of the release liner 2 is suppressed even if the offset portion 21 comes into contact with the conveying machine. Therefore, lifting of the adhesive layer 3 can be suppressed.

1.6.4 Tensile modulus E1 of release liner 2
The tensile modulus E1 of the release liner 2 at 23° C. is appropriately set so that the later-described relational value (E1×E2×(T1+T2)/[T0 ^1/2 ×100,000]) becomes a specific value. The tensile elastic modulus E1 of the release liner 2 at 23° C. is, for example, 1,000 MPa or higher, preferably 2,000 MPa or higher, more preferably 3,000 MPa or higher, and still more preferably 4,000 MPa or higher. The upper limit of the tensile modulus E1 of the release liner 2 at 23°C is, for example, 10,000 MPa.

The tensile modulus E1 of the release liner 2 at 23°C is determined based on the stress-strain curve. Details of the measurements are described in the Examples.

1.6.5 Recess 25 in release liner 2
One side of the release liner 2 in the thickness direction comprises, for example, recesses 25 . The recessed portion 25 is recessed toward the other side in the thickness direction around the peripheral edge of the adhesive layer 3 . The depth of the concave portion 25 is, for example, 30 μm or less, preferably 25 μm or less, more preferably 20 μm or less, even more preferably 10 μm or less, particularly preferably 1 μm or less. The lower limit of the depth of the concave portion 25 is, for example, 0.001 μm and 0 μm. If the depth of the concave portion 25 is equal to or less than the upper limit described above, it is possible to prevent the release liner 2 from being cut starting from the concave portion 25 .

1.6.6 Tensile modulus E2 of adjacent layer 4
The tensile elastic modulus E2 of the adjacent layer 4 at 23° C. is appropriately set so that a relational value, which will be described later, becomes a specific value. The tensile elastic modulus E2 of the adjacent layer 4 at 23° C. is, for example, 50 MPa or higher, preferably 100 MPa or higher, more preferably 150 MPa or higher, even more preferably 250 MPa or higher, particularly preferably 600 MPa or higher, and 1, 000 MPa or more, 2,000 MPa or more, 3,000 MPa or more, and 4,000 MPa or more are suitable. The upper limit of the tensile modulus E2 of the adjacent layer 4 at 23° C. is, for example, 15,000 MPa, preferably 10,000 MPa, more preferably 7,500 MPa, 5,000 MPa.

The tensile elastic modulus E2 of the adjacent layer 4 at 23° C. is obtained based on the stress-strain curve. Details of the measurements are described in the Examples.

The second release liner is flexible.

1.6.7 Relationship values between adhesive layer 3, release liner 2, and adjacent layer 4 The adhesive layer 3, release liner 2, and adjacent layer 4 preferably satisfy the following formula [1] satisfies the following formula [2], more preferably satisfies the following formula [3], more preferably satisfies the following formula [4], further satisfies the following formula [5], and further , satisfies the following formula [6], satisfies the following formula [7], and satisfies the following formula [8]. Also, the upper limit of the left side in each of the above formulas is, for example, 100,000, and is, for example, 10,000.

E1×E2×(T1+T2)/[T0 ^1/2 ×100,000]≧500
[1]

E1×E2×(T1+T2)/[T0 ^1/2 ×100,000]≧1,000
[2]

E1×E2×(T1+T2)/[T0 ^1/2 ×100,000]≧2,500
[3]

E1×E2×(T1+T2)/[T0 ^1/2 ×100,000]≧3,000
[4]

E1×E2×(T1+T2)/[T0 ^1/2 ×100,000]≧4,000
[5]

E1×E2×(T1+T2)/[T0 ^1/2 ×100,000]≧5,000
[6]

E1×E2×(T1+T2)/[T0 ^1/2 ×100,000]≧6,000
[7]

E1×E2×(T1+T2)/[T0 ^1/2 ×100,000]≧7,000
[8]

E1: Tensile modulus of release liner 2 at 23°C (MPa)
E2: Tensile elastic modulus (MPa) of adjacent layer 4 at 23°C
T1: Thickness of release liner 2 (μm)
T2: thickness of adjacent layer 4 (μm)
T0: Thickness of adhesive layer 3 (μm)

When the above formula is satisfied, it is selected from the group consisting of the thickness T1 of the release liner 2, the tensile modulus E1 of the release liner 2, the thickness T2 of the adjacent layer 4, and the tensile modulus E2 of the adjacent layer 4. at least one of the Therefore, even if the adhesive layer 3 is thick, that is, even if the thickness T0 is large, the release liner 2 and/or the adjacent layer 4 tend to harden, so the deflection amount D of the optical adhesive sheet 1 can be reduced.

Alternatively, when the above formula is satisfied, the adhesive layer 3 is thin. Therefore, at least one selected from the group consisting of the thickness T1 of the release liner 2, the tensile modulus E1 of the release liner 2, the thickness T2 of the adjacent layer 4, and the tensile modulus E2 of the adjacent layer 4 The optical adhesive sheet 1 can ensure the toughness even if the ridges are small. Therefore, the deflection amount D of the optical adhesive sheet 1 can be reduced.

1.7 Materials for Each Layer 1.7.1 Material for Adhesive Layer 3 The adhesive layer 3 is a sheet-like pressure-sensitive adhesive formed from an adhesive composition. The adhesive composition contains at least a base polymer.

The base polymer is an adhesive component that allows the adhesive layer 3 to exhibit adhesiveness. Base polymers include, for example, acrylic polymers, silicone polymers, polyester polymers, polyurethane polymers, polyamide polymers, polyvinyl ether polymers, vinyl acetate/vinyl chloride copolymers, modified polyolefin polymers, epoxy polymers, fluoropolymers, and rubber polymers. . A base polymer may be used independently and two or more types may be used together. From the viewpoint of ensuring good transparency and adhesiveness in the adhesive layer 3, acrylic polymer is preferably used as the base polymer.

The acrylic polymer is a copolymer of monomer components containing 50% by mass or more of (meth)acrylic acid ester. "(Meth)acrylic" means acrylic and/or methacrylic.

As the (meth)acrylic acid ester, an alkyl (meth)acrylic acid ester is preferably used, and an alkyl (meth)acrylic acid ester having an alkyl group having 1 to 20 carbon atoms is more preferably used. The (meth)acrylic acid alkyl ester may have a linear or branched alkyl group, or may have a cyclic alkyl group such as an alicyclic alkyl group.

Examples of (meth)acrylic acid alkyl esters having a linear or branched alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and isobutyl (meth)acrylate. , s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, isopentyl (meth)acrylate, neopentyl (meth)acrylate, hexyl (meth)acrylate, (meth)acrylate Heptyl acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, (meth) ) isodecyl acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate (that is, lauryl acrylate), isotridecyl (meth) acrylate, tetradecyl (meth) acrylate, isotetradecyl (meth) acrylate, (meth) pentadecyl acrylate, cetyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, isooctacyl (meth)acrylate, and nonadecyl (meth)acrylate.

Examples of (meth)acrylic acid alkyl esters having an alicyclic alkyl group include (meth)acrylic acid cycloalkyl esters, (meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring, and tricyclic (Meth)acrylic acid esters having the above aliphatic hydrocarbon ring can be mentioned. (Meth)acrylic acid cycloalkyl esters include, for example, cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, cycloheptyl (meth)acrylate, and cyclooctyl (meth)acrylate. (Meth)acrylic acid esters having a bicyclic aliphatic hydrocarbon ring include, for example, isobornyl (meth)acrylate. (Meth)acrylic esters having a tricyclic or higher aliphatic hydrocarbon ring include, for example, dicyclopentanyl (meth)acrylate, dicyclopentanyloxyethyl (meth)acrylate, tricyclopentanyl (meth)acrylate , 1-adamantyl (meth)acrylate, 2-methyl-2-adamantyl (meth)acrylate, and 2-ethyl-2-adamantyl (meth)acrylate.

As the (meth)acrylic acid alkyl ester, an acrylate alkyl ester having an alkyl group having 3 to 15 carbon atoms is preferably used, and more preferably n-butyl acrylate, 2-ethylhexyl acrylate, and acrylic acid. At least one selected from the group consisting of dodecyl acid is used.

The ratio of the (meth)acrylic acid alkyl ester in the monomer component is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass, from the viewpoint of appropriately expressing adhesiveness in the adhesive layer 3. above, and more preferably at least 92% by mass. The same ratio is, for example, 99% by mass or less.

The monomer component may also contain a copolymerizable monomer copolymerizable with the (meth)acrylic acid alkyl ester. Examples of copolymerizable monomers include monomers having a polar group. Polar group-containing monomers include, for example, hydroxyl group-containing monomers, carboxy group-containing monomers, and monomers having a nitrogen atom-containing ring. The polar group-containing monomer is useful for modifying the acrylic polymer, such as introducing cross-linking points into the acrylic polymer and securing the cohesive strength of the acrylic polymer.

Examples of hydroxy group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, ( 4-hydroxybutyl meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and , (4-Hydroxymethylcyclohexyl)methyl (meth)acrylate. As the hydroxy group-containing monomer, preferably at least one selected from the group consisting of 4-hydroxybutyl acrylate and 2-hydroxyethyl acrylate is used.

The ratio of the hydroxy group-containing monomer in the monomer component is, for example, 1% by mass or more, preferably 2% by mass or more, from the viewpoint of introducing a crosslinked structure into the acrylic polymer and ensuring cohesive force in the adhesive layer 3. Preferably, it is 3% by mass or more. The same ratio is preferably 20% by mass or less, preferably 10% by mass or less, from the viewpoint of adjusting the polarity of the acrylic polymer (related to the compatibility between the various additive components and the acrylic polymer in the adhesive layer 3). .

Carboxy group-containing monomers include, for example, acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

The ratio of the carboxy group-containing monomer in the monomer component is, for example, 0 from the viewpoint of introducing a crosslinked structure into the acrylic polymer, ensuring cohesive force in the adhesive layer 3, and ensuring adhesion to the adherend in the adhesive layer 3. 0.1% by mass or more, preferably 0.5% by mass or more, more preferably 0.8% by mass or more. The ratio is preferably 10% by mass or less, preferably 5% by mass or less, from the viewpoints of adjusting the glass transition temperature of the acrylic polymer and avoiding the risk of acid corrosion of the adherend.

Examples of monomers having a nitrogen atom-containing ring include N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-(meth)acryloyl-2-pyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-vinylmorpholine, N-vinyl -3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N -vinylthiazole and N-vinylisothiazole. N-vinyl-2-pyrrolidone is preferably used as the monomer having a nitrogen atom-containing ring.

The ratio of the monomer having a nitrogen atom-containing ring in the monomer component is, for example, 0.1% by mass or more from the viewpoint of ensuring the cohesive force in the adhesive layer 3 and ensuring the adhesion to the adherend in the adhesive layer 3. , preferably 0.5% by mass or more, more preferably 1% by mass or more. The same ratio is preferably 30% by mass from the viewpoint of adjusting the glass transition temperature of the acrylic polymer and adjusting the polarity of the acrylic polymer (related to compatibility between various additive components and the acrylic polymer in the adhesive layer 3). Below, preferably, it is 20 mass % or less.

The monomer component may contain other copolymerizable monomers. Other copolymerizable monomers include, for example, acid anhydride monomers, sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, epoxy group-containing monomers, cyano group-containing monomers, alkoxy group-containing monomers, and aromatic vinyl compounds. mentioned. These other copolymerizable monomers may be used alone, or two or more of them may be used in combination.

The base polymer preferably has a crosslinked structure. Methods for introducing a crosslinked structure into the base polymer include the first method and the second method. These methods may be used in combination.

In the first method, a base polymer having a functional group capable of reacting with a cross-linking agent and a cross-linking agent are blended into an adhesive composition, and the base polymer and the cross-linking agent are allowed to react in the adhesive layer 3 . In the second method, a polyfunctional monomer is included in the monomer components forming the base polymer, and the base polymer is formed by polymerizing the monomer components to introduce a branched structure (crosslinked structure) into the polymer chain.

Cross-linking agents used in the first method include, for example, compounds that react with functional groups (hydroxy groups, carboxy groups, etc.) contained in the base polymer. Such crosslinkers include, for example, isocyanate crosslinkers, peroxide crosslinkers, epoxy crosslinkers, oxazoline crosslinkers, aziridine crosslinkers, carbodiimide crosslinkers, and metal chelate crosslinkers. A cross-linking agent may be used independently and two or more types may be used together. As the cross-linking agent, an isocyanate cross-linking agent, a peroxide cross-linking agent, and an epoxy cross-linking agent are preferable because they are highly reactive with the hydroxy groups and carboxy groups in the base polymer and facilitate the introduction of a cross-linked structure. Used.

Examples of isocyanate cross-linking agents include tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, isocyanates and polymethylene polyphenyl isocyanates. The isocyanate cross-linking agent also includes derivatives of these isocyanates. Isocyanate derivatives include, for example, isocyanurate modified products and polyol modified products. Commercially available isocyanate cross-linking agents include, for example, Coronate L (trimethylolpropane adduct of tolylene diisocyanate, manufactured by Tosoh), Coronate HL (trimethylolpropane adduct of hexamethylene diisocyanate, manufactured by Tosoh), Coronate HX (hexa isocyanurate of methylene diisocyanate, manufactured by Tosoh), Takenate D110N (trimethylolpropane adduct of xylylene diisocyanate, manufactured by Mitsui Chemicals), and Takenate 600 (1,3-bis(isocyanatomethyl)cyclohexane, manufactured by Mitsui Chemicals) is mentioned.

Peroxide crosslinking agents include dibenzoyl peroxide, di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t- butyl peroxyneodecanoate, t-hexyl peroxypivalate, and t-butyl peroxypivalate.

Examples of epoxy cross-linking agents include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane triglycidyl ether. , diglycidylaniline, diamine glycidylamine, N,N,N′,N′-tetraglycidyl-m-xylylenediamine, and 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane.

From the viewpoint of ensuring the cohesive force of the adhesive layer 3, the amount of the cross-linking agent is, for example, 0.01 parts by mass or more, preferably 0.05 parts by mass or more, or more with respect to 100 parts by mass of the base polymer. Preferably, it is 0.07 parts by mass or more. From the viewpoint of ensuring good tackiness in the adhesive layer 3, the amount of the cross-linking agent blended with respect to 100 parts by mass of the base polymer is, for example, 10 parts by mass or less, preferably 5 parts by mass or less, more preferably 3 parts by mass. It is below the department.

In the second method, the monomer components may be polymerized in one step or in multiple stages. The monomer component includes a polyfunctional monomer for introducing a crosslinked structure and other monomers. In the multi-stage polymerization method, first, a monofunctional monomer for forming the base polymer is polymerized (prepolymerization), thereby containing a partially polymerized product (a mixture of a polymerized product with a low degree of polymerization and an unreacted monomer). A prepolymer composition is prepared. Next, after adding a polyfunctional monomer to the prepolymer composition, the partial polymer and the polyfunctional monomer are polymerized (main polymerization).

Examples of polyfunctional monomers include polyfunctional (meth)acrylates containing two or more ethylenically unsaturated double bonds in one molecule. As the polyfunctional monomer, a polyfunctional acrylate is preferable from the viewpoint that a crosslinked structure can be introduced by active energy ray polymerization (photopolymerization).

Polyfunctional (meth)acrylates include bifunctional (meth)acrylates, trifunctional (meth)acrylates, and tetrafunctional or higher polyfunctional (meth)acrylates.

Examples of bifunctional (meth)acrylates include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol dimethacrylate, 1,6-hexanediol di (meth)acrylates, 1,9-nonanediol di(meth)acrylate, glycerin di(meth)acrylate, neopentyl glycol di(meth)acrylate, stearic acid-modified pentaerythritol di(meth)acrylate, dicyclopentenyl diacrylate, Di(meth)acryloyl isocyanurate and alkylene oxide-modified bisphenol di(meth)acrylate can be mentioned.

Trifunctional (meth)acrylates include, for example, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and tris(acryloyloxyethyl)isocyanurate.

Tetra- or higher polyfunctional (meth)acrylates include, for example, ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol monohydroxypenta(meth)acrylate, and alkyl-modified dipentaerythritol pentaacrylate. , and dipentaerythritol hexa(meth)acrylate.

An acrylic polymer is obtained by polymerizing the above monomer components using a known method.

In polymerization, a chain transfer agent may be used for the purpose of molecular weight adjustment. Chain transfer agents include α-thioglycerol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-mercaptoethanol, thioglycolic acid, 2-ethylhexyl thioglycolate, 2,3-dimercapto-1-propanol, and α-methyl Styrene dimers are mentioned.

The weight-average molecular weight of the base polymer is, for example, 100,000 or more, preferably 300,000 or more, and more preferably 500,000 or more, from the viewpoint of ensuring cohesive force in the adhesive layer 3 . The weight average molecular weight is, for example, 5 million or less, preferably 3 million or less, more preferably 2 million or less. The weight average molecular weight of the base polymer is measured by gel permeation chromatography (GPC) and calculated by polystyrene conversion.

The glass transition temperature (Tg) of the base polymer is, for example, 0° C. or lower, preferably -10° C. or lower, more preferably -20° C. or lower. The glass transition temperature is, for example, −80° C. or higher. The glass transition temperature (Tg) of the base polymer is determined based on the Fox equation.

The adhesive composition may contain one or more oligomers in addition to the base polymer. When an acrylic polymer is used as the base polymer, preferably an acrylic oligomer is used as the oligomer. The acrylic oligomer is a copolymer of monomer components containing 50% by mass or more of (meth)acrylic acid alkyl ester, and has a weight average molecular weight of, for example, 1,000 or more and 30,000 or less.

The glass transition temperature of the acrylic oligomer is, for example, 60° C. or higher, preferably 80° C. or higher, more preferably 100° C. or higher, still more preferably 110° C. or higher. The glass transition temperature of the acrylic oligomer is, for example, 200° C. or lower, preferably 180° C. or lower, and preferably 160° C. or lower. The combined use of a low-Tg acrylic polymer (base polymer) introduced with a cross-linked structure and a high-Tg acrylic oligomer can increase the adhesive strength of the adhesive layer 3, especially at high temperatures. The glass transition temperature of the acrylic oligomer is obtained based on the Fox formula.

The acrylic oligomer having a glass transition temperature of 60° C. or higher is preferably a (meth)acrylic acid alkyl ester having a chain alkyl group (chain alkyl (meth)acrylate) and a (meth)acrylic acid having an alicyclic alkyl group. It is a polymer of a monomer component containing an acid alkyl ester (alicyclic alkyl (meth)acrylate). Specific examples of these (meth)acrylic acid alkyl esters include, for example, the (meth)acrylic acid alkyl esters described above as the monomer component of the acrylic polymer.

As the chain alkyl (meth)acrylate, methyl methacrylate is preferable because it has a high glass transition temperature and excellent compatibility with the base polymer. Dicyclopentanyl acrylate is preferred as the alicyclic alkyl (meth)acrylate.

The ratio of the alicyclic alkyl (meth)acrylate in the monomer component of the acrylic oligomer is, for example, 10% by mass or more, preferably 20% by mass or more, and more preferably 30% by mass or more. The same ratio is, for example, 90% by mass or less, preferably 80% by mass or less, more preferably 70% by mass or less. The proportion of chain alkyl (meth)acrylate in the monomer component of the acrylic oligomer is, for example, 90% by mass or less, preferably 80% by mass or less, more preferably 70% by mass or less. The same ratio is, for example, 10% by mass or more, preferably 20% by mass or more, more preferably 30% by mass or more.

The weight average molecular weight of the acrylic oligomer is, for example, 1,000 or more, preferably 1,500 or more, more preferably 2,000 or more. The molecular weight is, for example, 30,000 or less, preferably 10,000 or less, more preferably 8,000 or less. Such a molecular weight range of the acrylic oligomer is preferable for securing the adhesive strength and adhesive holding power of the pressure-sensitive adhesive layer 3 .

Acrylic oligomers are obtained by polymerizing monomer components of acrylic oligomers using a known method.

In order to sufficiently increase the adhesive strength of the adhesive layer 3, the content of the acrylic oligomer in the adhesive layer 3 is, for example, 0.5 parts by mass or more, more preferably 0.8 parts by mass, with respect to 100 parts by mass of the base polymer. It is at least 1 part by mass, more preferably at least 1 part by mass. On the other hand, from the viewpoint of ensuring the transparency of the adhesive layer 3, the content of the acrylic oligomer in the adhesive layer 3 is, for example, 5 parts by mass or less, more preferably 4 parts by mass or less with respect to 100 parts by mass of the base polymer. , more preferably 3 parts by mass or less. In the adhesive layer 3, when the content of the acrylic oligomer is too large, the haze tends to increase and the transparency tends to decrease due to the decrease in the compatibility of the acrylic oligomer.

The adhesive composition may contain a silane coupling agent. The content of the silane coupling agent in the pressure-sensitive adhesive composition is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, relative to 100 parts by mass of the base polymer. The content is preferably 5 parts by mass or less, more preferably 3 parts by mass or less.

The pressure-sensitive adhesive composition may contain other components as necessary. Other components include, for example, solvents, tackifiers, plasticizers, softeners, antioxidants, fillers, colorants, dyes, pigments, ultraviolet absorbers, antioxidants, infrared absorbers, surfactants, Catalysts, particles, UV curable monomers, UV curable oligomers, UV curable resins, photoinitiators, metals, fibers, conductive materials, and antistatic agents.

1.7.2 Materials for Release Liner 2 Materials for the release liner 2 include flexible materials. A specific example of the release liner 2 is plastic. Examples of plastics include acrylics such as polyester, polyolefin, polyimide, polyetheretherketone (PEEK), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), and polymethyl methacrylate (PMMA). Resin, polycarbonate, triacetyl cellulose (TAC), polysulfone, polyarylate, polyethylene (PE), polypropylene (PP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA), polyamide (nylon), all Aromatic polyamide (aramid), polyvinyl chloride (PVC), polyvinyl acetate, polyphenylene sulfide (PPS), fluororesin, cyclic olefin polymer, cycloolefin, polyurethane, and the like.

As a material for the release liner 2, polyester is preferably used from the viewpoint of increasing the tensile elastic modulus E1.

A release layer (not shown) may be formed on one side of the release liner 2 in the thickness direction. The release layer is a layer formed by a release treatment with a release treatment agent on one surface of the release liner 2 in the thickness direction. Release treatments include, for example, silicone release treatments, long-chain alkyl acrylate release treatments, and fluorine release treatments. That is, the release layer includes, for example, a silicone release layer, a long-chain alkyl acrylate release layer, and a fluorine release layer. The release layer is preferably a silicone release layer from the viewpoint of ease of adjustment of the release force from the adhesive layer 3 .

1.7.3 Materials for Adjacent Layer 4 Materials for the adjacent layer 4 include flexible materials. Adjacent layer 4 specifically includes plastic. Plastics include those exemplified for the release liner 2 . A release layer (not shown) may be formed on the other surface of the adjacent layer 4 in the thickness direction.

1.8 Method for Manufacturing Optical Adhesive Sheet 1 A method for manufacturing the optical adhesive sheet 1 will be described with reference to FIGS. 3A to 3D. In this manufacturing method, first, a laminate 51 is produced (see FIG. 3A), then the adhesive layer 3 is trimmed (see FIG. 3B), unnecessary portions 53 are removed (see FIG. 3C), and then The release liner 2 is contoured (see Figure 3D) and then the third release liner 5 is relined to the adjacent layer 4 (see Figure 3D).

As shown in FIG. 3A, the laminate 51 has, for example, a long sheet shape. The laminate 51 includes a release liner 2, an adhesive layer 3, and a third release liner 5 in order toward one side in the thickness direction.

The release force of the third release liner 5 is small. Specifically, the peel force for peeling the third release liner 5 from the adhesive layer 3 is smaller than the peel force for peeling the release liner 2 from the adhesive layer 3 . The surface of the third release liner 5 is subjected to, for example, a known release treatment. The third release liner 5 is also a protective material that protects one surface of the pressure-sensitive adhesive layer 3 (coating film 31) during the manufacturing process.

In order to produce the laminate 51, for example, the release liner 2 is prepared, then the pressure-sensitive adhesive composition is applied to one side of the release liner 2 in the thickness direction to form the coating film 31, and then, A third release liner 5 is placed on one side of the coating film 31 in the thickness direction, and then the coating film 31 is dried or irradiated with light.

Examples of the method for contouring the adhesive layer 3 include laser irradiation and cutting with a cutting blade. A laser is applied from one side in the thickness direction toward the laminate 51 , or a blade is inserted toward the laminate 51 .

As a method for contouring the adhesive layer 3, laser irradiation is preferably used from the viewpoint of shallowing the concave portion 25. As shown in FIG.

Lasers include, for example, gas lasers, solid-state lasers, and semiconductor lasers. Gas lasers include, for example, excimer lasers and _CO2 lasers (10.6 μm).

The adhesive layer 3 is contour-processed into a shape having the above-described length L by the contour processing described above. Along with this, the third release liner 5 is also contoured to have the same shape and size as the adhesive layer 3 . As a result, cuts 26 are formed in the adhesive layer 3 and the third release liner 5 . The adhesive layer 3 has the length L described above.

At the same time, a concave portion 25 is unintentionally (inevitably) formed on one side of the release liner 2 in the thickness direction. Recess 25 is the bottom of notch 26 .

As shown in FIG. 3C, the unnecessary portion 53 is removed. The unnecessary portion 53 is the portion of the adhesive layer 3 and the third release liner 5 located outside the cut 26 . A method for removing the unnecessary portion 53 includes, for example, removal using a take-up roll.

As shown in FIG. 3D, the third release liner 5 is replaced with the adjacent layer 4 and the release liner 2 is trimmed.

When re-covering the adjacent layer 4 , the third release liner 5 is peeled off from one side of the adhesive layer 3 in the thickness direction, as indicated by the phantom lines in FIG. 3C . to place.

A long release liner 2 is contoured into a pattern that is larger than and encompasses the adhesive layer 3 . The shape processing of the release liner 2 includes laser irradiation and cutting with a cutting blade.

After that, the adhesive layer 3 is aged if necessary. The aging temperature is, for example, 50°C to 100°C. Aging times range from 30 minutes to 3 days.

Thereby, the optical adhesive sheet 1 including the release liner 2, the adhesive layer 3, and the adjacent layer 4 is manufactured.

As shown in FIG. 4, the adhesive layer 3 in the optical adhesive sheet 1 is attached to the image display device member 11 .

The image display device member 11 extends along the surface direction. The image display device member 11 has a sheet shape. The image display device member 11 is an element provided in the image display device 20 (see FIG. 5). Specifically, the image display device member 11 includes, for example, an optical substrate, a pixel panel, a polarizing plate, a touch panel, and a cover film. Examples of optical substrates include glass films (ultra-thin glass, UTG), polyester films, polyolefin films, and polyimide films. Polyester films include, for example, polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film. Polyolefin films include, for example, polyethylene films, polypropylene films, and cycloolefin films. Pixel panels include LCD panels, OLED panels, miniLED, μLED panels, and the like.

The member 11 for an image display device has a single layer or multiple layers. As shown by the phantom lines in FIG. 4, for example, the image display device member 11 includes a first layer 111 and a second layer 112 in order toward one side in the thickness direction. Examples of the first layer 111 include an optical substrate and a polarizing plate. Examples of the second layer 112 include a cover film.

The image display device member 11 is another example of the adjacent layer 4 . The optical adhesive sheet 1 includes a release liner 2, an adhesive layer 3, and an image display device member 11 in order toward one side in the thickness direction.

The peripheral edge of the image display device member 11 coincides with the peripheral edge of the adhesive layer 3 .

An undercoat layer may be formed on the other side of the image display device member 11 in the thickness direction as shown. In this case, the image display device member 11 is adhered (formed) to one surface of the adhesive layer 3 in the thickness direction via the undercoat layer.

In order to manufacture the optical adhesive sheet 1 shown in FIG. 4, the third release liner 5 is peeled off from the adhesive layer 3 as shown by the phantom lines in FIG. 3C, and then, as shown in FIG. The member 11 is attached to one surface of the adhesive layer 3 in the thickness direction.

1.9 Image display device 20
As shown in FIG. 5, the adhesive layer 3 is attached to another image display device member 12 . Specifically, the image display device 20 includes an adhesive layer 3 and a pair of image display device members 11 and 12 .

The adhesive layer 3 and the image display device member 11 in FIG. 5 are the same as the adhesive layer 3 and the image display device member 11 in the optical adhesive sheet 1 shown in FIG.

The image display device member 12 is arranged on the side opposite to the image display device member 11 with respect to the adhesive layer 3 in the thickness direction. Specifically, the image display device member 12 is arranged on the other surface of the adhesive layer 3 in the thickness direction. An undercoat layer may be formed on one surface of the image display device member 12 in the thickness direction as shown. In this case, the image display device member 12 is adhered (formed) to the adhesive layer 3 via the undercoat layer. Examples of the image display device member 12 include the elements exemplified for the image display device member 11 described above.

The peripheral edge of the image display device member 12 coincides with the peripheral edge of the adhesive layer 3 when viewed in the thickness direction. In this embodiment, the peripheral end surfaces of the pair of image display device members 11 and 12 and the peripheral end surface of the adhesive layer 3 are flush with each other.

2. Effects of One Embodiment In this optical adhesive sheet 1, since the maximum length L of the adhesive layer 3 is 200 mm or more, the adhesive layer 3 can be attached to a member of a large image display device such as a tablet.

In addition, even if the above length L is 200 mm or more, in this optical adhesive sheet 1, the release liner 2 is larger than the adhesive layer 3 when viewed in the thickness direction, and includes the adhesive layer 3. The release liner 2 prevents the edge of the adhesive layer 3 from sticking out. Therefore, contamination of the surroundings by the above-described adhesive layer 3 can be suppressed.

Furthermore, in this optical adhesive sheet 1, since the end portions of the adhesive layer 3 are suppressed from protruding, the handleability is excellent.

Furthermore, in this optical adhesive sheet 1, the edge portions of the adhesive layer 3 are suppressed from protruding.

If the deflection amount D of the optical adhesive sheet 1 is 7 mm or less, the optical adhesive sheet 1 is even more excellent in handleability.

Further, in the optical adhesive sheet 1, when the area P, which is the product of the offset amount OL of the release liner 2 and the thickness T1 of the release liner 2, is 90×10 ⁻⁸ m ² or more, the adhesive layer 3 is Floating from the release liner 2 can be suppressed.

Specifically, when the area P is 90×10 ⁻⁸ m ² or more, the offset amount OL of the release liner 2 is large even if the thickness T1 of the release liner 2 is small. Therefore, even if the offset portion 21 deforms, the deformation does not easily affect the adhesive layer 3 . Therefore, it is possible to prevent the adhesive layer 3 from unintentionally peeling off from the release liner 2 .

Alternatively, when the area P is 90×10 ⁻⁸ m ² or more, the release liner 2 is thick even if the offset amount OL of the release liner 2 is small. In this case, deformation of the release liner 2 is suppressed even if the offset portion 21 comes into contact with the conveying machine. Therefore, lifting of the adhesive layer 3 can be suppressed.

Further, in the optical adhesive sheet 1, when the above formula [3] is satisfied, the thickness T1 of the release liner 2, the tensile elastic modulus E1 of the release liner 2, the thickness T2 of the adjacent layer 4, and the adjacent layer 4, and at least one selected from the group consisting of the tensile elastic modulus E2 is large. Therefore, even if the pressure-sensitive adhesive layer 3 is thick, the release liner 2 and/or the adjacent layer 4 tend to harden, so that the deflection amount D of the optical pressure-sensitive adhesive sheet 1 can be reduced.

Alternatively, when the above formula [3] is satisfied, the adhesive layer 3 is thin. Therefore, at least one selected from the group consisting of the thickness T1 of the release liner 2, the tensile modulus E1 of the release liner 2, the thickness T2 of the adjacent layer 4, and the tensile modulus E2 of the adjacent layer 4 Since the optical pressure-sensitive adhesive sheet 1 can ensure toughness even if the diameter of the optical pressure-sensitive adhesive sheet 1 is small, the amount of deflection D of the optical pressure-sensitive adhesive sheet 1 can be reduced.

In addition, in the optical adhesive sheet 1, the second release liner 4A, which is an example of the adjacent layer 4, is larger than the adhesive layer 3 when viewed in the thickness direction and includes the adhesive layer 3. With 4A, protrusion of the edge of the adhesive layer 3 is further suppressed, and the handleability of the optical adhesive sheet 1 is further improved.

Further, in this optical adhesive sheet 1, the area P2, which is the product of the second offset amount OL2 of the second release liner 4A, which is an example of the adjacent layer 4, and the thickness T2 of the second release liner 4A, is 90×10 ⁻⁸ . When it is m ² or more, it is possible to prevent the adhesive layer 3 from floating from the second release liner 4A.

Specifically, when the area P2 is 90×10 ⁻⁸ m ² or more, the second offset amount OL2 of the second release liner 4A is large, and even if the second offset portion 41 is deformed, such deformation will not occur. It hardly affects the adhesive layer 3. Therefore, it is possible to prevent the adhesive layer 3 from unintentionally peeling off from the second release liner 4A.

Alternatively, when the area P2 is 90×10 ⁻⁸ m ² or more, the second release liner 4A is thick. In this case, deformation of the second release liner 4A is suppressed even if the offset portion 21 comes into contact with the conveying machine. Therefore, lifting of the adhesive layer 3 can be suppressed.

Further, in this optical adhesive sheet 1, if the depth of the recesses 25 is 30 μm or less, it is possible to suppress the release liner 2 from being cut from the recesses 25 as a starting point.

Further, in this optical adhesive sheet 1, if the indentation hardness H of the adhesive layer 3 at 23° C. is 10 kPa or less, the adhesive layer 3 is suitable for pasting members in a repeatedly foldable image display device. Used.

Further, in this optical adhesive sheet 1, if the shear storage elastic modulus G' of the adhesive layer 3 at 25°C is 100 kPa or less, the adhesive layer 3 can be repeatedly folded (foldable) for attachment of members in an image display device. It is preferably used for

3. Modifications In each modification below, the same reference numerals are given to the same members and steps as in the above-described embodiment, and detailed description thereof will be omitted. Moreover, each modification can have the same effects as the one embodiment, unless otherwise specified. Furthermore, one embodiment and modifications can be combined as appropriate.

As shown in FIG. 6, the optical adhesive sheet 1 of the modification includes a release liner 2 and an adhesive layer 3 in order toward one side in the thickness direction. The optical adhesive sheet 1 does not have the adjacent layer 4 . The optical adhesive sheet 1 of the modification includes only a release liner 2 and an adhesive layer 3.

To manufacture the modified optical adhesive sheet 1, the third release liner 5 indicated by the phantom lines in FIG. 3C is peeled off from the adhesive layer 3.

Comparing the one embodiment and the modification, one embodiment is preferable. In one embodiment, the adjacent layer 4 can suppress contamination of one surface of the adhesive layer 3 in the thickness direction.

Although not shown, the adjacent layers 4 have the same size when viewed in the thickness direction. In this modification, the peripheral side surface of the adjacent layer 4 is flush with the peripheral side surface of the adhesive layer 3 .

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. It should be noted that the present invention is by no means limited to the examples. In addition, specific numerical values such as the mixing ratio (content ratio), physical property values, and parameters used in the following description are the corresponding mixing ratios ( content ratio), physical properties, parameters, etc. can.

(Preparation of adhesive composition A to adhesive composition E)
Preparation A

60 parts by mass of dicyclopentanyl methacrylate (DCPMA) and 40 parts by mass of methyl methacrylate (MMA) as monomer components, 3.5 parts by mass of α-thioglycerol as a chain transfer agent, and 100 parts by mass of toluene as a polymerization solvent. Mix and stir at 70° C. for 1 hour under a nitrogen atmosphere. Next, 0.2 parts by mass of 2,2′-azobisisobutyronitrile (AIBN) was added as a thermal polymerization initiator, reacted at 70° C. for 2 hours, and then heated to 80° C. for 2 hours. reacted. After that, the reaction solution was heated to 130° C., and toluene and unreacted monomers were removed by drying to obtain a solid acrylic oligomer (oligomer (1)). Oligomer (1) had a weight average molecular weight of 5,100 and a glass transition temperature (Tg) of 130°C.

Separately, 40 parts by mass of lauryl acrylate (LA), 46 parts by mass of 2-ethylhexyl acrylate (2EHA), 7 parts by mass of 4-hydroxybutyl acrylate (4HBA), and N-vinyl-2- 7 parts by mass of pyrrolidone (NVP) and 0.015 parts by mass of BASF's "Irgacure 184" as a photopolymerization initiator were blended and irradiated with ultraviolet rays to polymerize, prepolymer composition A (polymerization rate of about 10 %) was obtained.

Then, to 100 parts by mass of the prepolymer composition A, 0.07 parts by mass of 1,6-hexanediol diacrylate (HDDA), 5 parts by mass of oligomer (1), and a silane coupling agent (Shin-Etsu Chemical ("KBM403") was added, and these were uniformly mixed to prepare a pressure-sensitive adhesive composition A.

Preparation B
As monomer components for forming the prepolymer, 30 parts by mass of lauryl acrylate (LA), 65 parts by mass of 2-ethylhexyl acrylate (2EHA), 8 parts by mass of 4-hydroxybutyl acrylate (4HBA), and N-vinyl-2-pyrrolidone ( NVP) 4 parts by mass and 0.015 parts by mass of "Irgacure 184" manufactured by BASF as a photopolymerization initiator, and polymerized by irradiating ultraviolet rays to form a prepolymer composition B (polymerization rate of about 10%). got

Then, to 100 parts by mass of the prepolymer composition B, 0.07 parts by mass of 1,6-hexanediol diacrylate (HDDA), 5 parts by mass of the above oligomer (1), and a silane coupling agent ( After adding 0.3 parts by mass of "KBM403" manufactured by Shin-Etsu Chemical Co., Ltd., these were uniformly mixed to prepare an adhesive composition B.

Preparation C
Lauryl acrylate (LA) 9 parts by mass, 2-ethylhexyl acrylate (2EHA) 68 parts by mass, and n-butyl acrylate (BA) 21 were placed in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser. parts by mass, 1 part by mass of 4-hydroxybutyl acrylate (4HBA), and 1 part by mass of N-vinyl-2-pyrrolidone (NVP), and 2,2'-azobisisobutyronitrile (AIBN) as a polymerization initiator ) was added, and ethyl acetate was charged so that the total concentration of these was 47% by weight. C. for 6 hours, and after completion of the reaction, ethyl acetate was added to adjust the polymer concentration to 24% by weight to obtain an acrylic polymer C solution. The weight average molecular weight of acrylic polymer C was 2,000,000.

Next, 100 parts by mass of acrylic polymer C, 0.25 parts by mass of peroxide (Nyper BMT-40SV, manufactured by NOF Corporation) as a cross-linking agent, 3 parts by mass of the above oligomer (1), and Irganox 1010 as an antioxidant 0.3 parts by mass (manufactured by BASF) and 0.01 parts by mass of Nasem ferric iron (manufactured by Nippon Kagaku Sangyo Co., Ltd.) as a catalyst are mixed and sufficiently stirred so that the total solid content is 21% by weight. Adhesive composition C was prepared by diluting with ethyl acetate.

Preparation D
A reaction vessel equipped with a condenser, nitrogen inlet, thermometer and stirrer was charged with a monomer mixture containing 99 parts of butyl acrylate (BA) and 1 part of 4-hydroxybutyl acrylate (HBA). Further, 0.1 part of 2,2'-azobisisobutyronitrile as a polymerization initiator was added to 100 parts of the above monomer mixture together with 100 parts of ethyl acetate. After the replacement, the liquid temperature in the flask was maintained at around 55° C., and the polymerization reaction was carried out for 8 hours to prepare a solution of an acrylic polymer having a weight-average molecular weight of 1,800,000 (solid concentration: 30% by weight). Per 100 parts of the solid content of the acrylic polymer (1) solution, 0.3 parts of a radical generator (benzoyl peroxide, trade name Nyper BMT manufactured by NOF Corporation), an isocyanate cross-linking agent (Mitsui Chemicals Co., Ltd.) and 0.1 part of a silane coupling agent (KBM403, manufactured by Shin-Etsu Chemical Co., Ltd.) were blended to prepare a pressure-sensitive adhesive composition D.

Preparation Example E
63 parts by mass of 2-ethylhexyl acrylate (2EHA), 15 parts by mass of N-vinyl-2-pyrrolidone (NVP), 9 parts by mass of methyl methacrylate (MMA), and 13 parts by mass of 2-hydroxyethyl acrylate (HEA) as monomer components Parts by mass, 0.2 parts by mass of 2,2'-azobisisobutyronitrile as a polymerization initiator, and 133 parts by mass of ethyl acetate as a polymerization solvent were put into a separable flask, and nitrogen gas was introduced. and stirred for 1 hour. After removing oxygen in the polymerization system in this way, the temperature is raised to 65° C. and the reaction is allowed to proceed for 10 hours. Thereafter, ethyl acetate is added to obtain a solution of acrylic polymer (f) having a solid concentration of 30% by weight. rice field.

Next, an isocyanate cross-linking agent (trade name “Takenate D110N”, manufactured by Mitsui Chemicals, Inc.) is added to the solution of the acrylic polymer (a) with respect to 100 parts by mass of the acrylic polymer (a) (solid content). It added so that it might become 1 mass part in conversion, and the adhesive composition E was prepared.

<Preparation of Release Liner 2 and Adjacent Layer 4>
A release liner 2 and an adjacent layer 4 as described in Table 1 below were prepared. Table 1 lists the materials and manufacturers of the release liner 2 and adjacent layer 4 .

(Example of Forming Adhesive Layer 3 from Adhesive Composition A)
(Example 1-Example 16, Example 20-Example 23, Example 25-Example 29)

(Example 1)
A release liner 2 made of MRF and having a thickness T1 of 25 μm and a third release liner 5 having a thickness of 75 μm were prepared. The third release liner 5 is a PET film (“Diafoil MRE75” manufactured by Mitsubishi Chemical Co., Ltd.) with one side subjected to silicone release treatment. Each of release liner 2 and third release liner 5 has an elongated shape.

On one side of the release liner 2, the pressure-sensitive adhesive composition A was applied to form a coating film 31 so that the thickness after drying was 25 μm. A third release liner 5 was adhered onto this coating film 31 . As a result, as shown in FIG. 3A, a laminate 51 having the release liner 2, the coating film 31, and the third release liner 5 in this order was produced. The laminated body 51 was irradiated with ultraviolet rays from one side of the laminated body 51 in the thickness direction with a black light whose position was adjusted so that the irradiation intensity on the irradiation surface directly below the lamp was 5 mW/cm ² , and photocuring was performed. , to prepare an adhesive layer 3 having a thickness of 25 μm.

Next, as shown in FIG. 3B, the adhesive layer 3 of the laminate 51 was contoured. Specifically, a cut 26 was formed in each of the adhesive layer 3 and the third release liner 5 by irradiating the laminate 51 with a CO ₂ laser in the thickness direction from the third release liner 5 side. As a result, the adhesive layer 3 and the third release liner 5 were cut in the thickness direction. On one side of the release liner 2, a recess 25 with a depth of 20 μm was formed. The longitudinal length L of the adhesive layer 3 was 250 mm.

Then, as shown in FIG. 3C, the outer portions of the cuts 26 in each of the adhesive layer 3 and the third release liner 5 were wound up using winding rolls.

The release liner 2 was then profiled as shown in FIG. 3D. The length L1 of the release liner 2 was 260 mm. The offset amount OL of the release liner 2 was 5 mm.

After that, an adjacent layer 4 having a length L2 of 250 mm was laminated on one side of the adhesive layer 3 . The peripheral side surface of the adjacent layer 4 was flush with the peripheral side surface of the adhesive layer 3 .

The laminate was then aged in an oven at 50°C for 1 day.

As a result, an optical adhesive sheet 1 having a release liner 2, an adhesive layer 3, and an adjacent layer 4 in this order was manufactured.

(Example 2-Example 16, Example 20-Example 23, Example 25-Example 29)
Optical adhesive sheet 1 was produced in the same manner as in Example 1. However, according to the descriptions in Tables 2 and 3, the release liner 2, the adhesive layer 3 and the adjacent layer 4 were changed in type, thickness, offset amount, second offset amount, and the like.

(Example of Forming Adhesive Layer 3 from Adhesive Composition B-Adhesive Composition E)
(Example 17)
Optical adhesive sheet 1 was produced in the same manner as in Example 1. However, according to the description in Table 2, the adhesive composition B was used in place of the adhesive composition A.

(Example 18)
Optical adhesive sheet 1 was produced in the same manner as in Example 1. However, according to the description in Table 2, the adhesive composition C was used in place of the adhesive composition A. Furthermore, in the preparation of the adhesive layer 3, heat curing was used instead of photocuring. Specifically, the coating film 31 on the release liner 2 and before the third release liner 5 was placed was dried at 130° C. for 3 minutes to form the adhesive layer 3 . Aging was carried out as in Example 1.

(Example 19)
Optical adhesive sheet 1 was produced in the same manner as in Example 1. However, according to the description in Table 2, the adhesive composition D was used in place of the adhesive composition A. Furthermore, in the preparation of the adhesive layer 3, heat curing was used instead of photocuring. Specifically, the coating film 31 on the release liner 2 and before the third release liner 5 was placed was dried at 130° C. for 3 minutes to form the adhesive layer 3 . Aging was carried out as in Example 1.

(Example of Forming Adhesive Layer 3 from Adhesive Composition E)
(Example 24)
Optical adhesive sheet 1 was produced in the same manner as in Example 1. However, according to the description in Table 3, the adhesive composition E was used in place of the adhesive composition A. Furthermore, in the preparation of the adhesive layer 3, heat curing was used instead of photocuring. Specifically, the coating film 31 on the release liner 2 and before the third release liner 5 was placed was dried at 130° C. for 3 minutes to form the adhesive layer 3 . Aging was carried out as in Example 1.

(evaluation)
The following items were evaluated for each of the optical adhesive sheets 1 of Examples 1 to 29. The results are listed in Tables 2 and 3.

(Offset amount OL, second offset amount OL2)
The offset amount OL of the release liner 2 and the second offset amount OL2 of the adjacent layer 4 in the optical adhesive sheet 1 were measured.

(Thickness T0, T1, T2)
The thickness T0 of the adhesive layer 3, the thickness T1 of the release liner 2, and the thickness T2 of the adjacent layer 4 in the optical adhesive sheet 1 were measured.

The thickness T1 of the release liner 2 was determined as the average thickness (μm) at three points in the offset portion. The thickness T2 of the adjacent layer 4 was determined as the average thickness (μm) at three points in the offset portion.

Subsequently, the area P, which is the product of the offset amount OL of the release liner 2 and the thickness T1, was determined. An area P2, which is the product of the second offset amount OL2 and the thickness T2 of the adjacent layer 4, was obtained.

(Bending amount D)
The deflection amount D of the optical adhesive sheet 1 was obtained by conducting the following deflection test.

Flexure test: A sample 100 was produced by shaping the optical adhesive sheet 1 to a size of 100 mm in length and mm in width. As shown in FIG. 2, a table 105 having an upper surface and a height of 50 mm or more was prepared. A surface of a first portion 101 having a length of 50 mm including one longitudinal edge of the sample was fixed to the upper surface. A 200 g weight 106 made of a glass plate was placed on the upper surface of the first portion 101 . A second portion 102 having a length of 50 mm, including the other longitudinal edge of the sample, protruded laterally from one edge of the upper surface. After that, it was left at 23° C. for 5 minutes. After that, the movement amount by which one end edge of the protruding sample moved downward from the upper surface was obtained. Separately, the back surface of the first part 101 was fixed to the upper surface, and the amount of movement was obtained. An average value of the two amounts of movement was obtained as the amount of deflection D.

(Indentation hardness H of adhesive layer 3)
In the optical adhesive sheet 1, the release liner 2 or the adjacent layer 4 was peeled off from the adhesive layer 3. Next, in an environment of 23° C., the surface of the adhesive layer 3 was subjected to an indentation test according to ISO14577 using a triboindenter (manufactured by Hysitron). In the indentation test, an indenter with a diameter of 20 μm was used, and the indenter was pushed into the adhesive layer 3 with an indentation depth of 2.5 μm. The indentation hardness H of the adhesive layer 3 was calculated from the maximum vertical load and the contact area.

(The tensile elastic modulus E1 of the release liner 2, the tensile elastic modulus E2 of the adjacent layer 4)
Measurement of the tensile elastic modulus E1 of the release liner 2 and the tensile elastic modulus E2 of the adjacent layer 4 in the optical adhesive sheet 1 will be described.

First, the central portion of the optical adhesive sheet 1 was trimmed to a size of 10 mm in width and 150 mm in length to prepare a sample. Note that the sample did not have the offset portion 21 or the second offset portion 41 . The peripheral end faces of the release liner 2, the adhesive layer 3 and the adjacent layer 4 in the sample were flush.

Subsequently, either one of the release liner 2 and the adjacent layer 4 was peeled off from the adhesive layer 3 . Thus, a sample consisting of one side and a laminated sample consisting of the other side and the adhesive layer 3 were prepared.

The sample is fixed in a tensile tester with a grip distance of 100 mm. A sample was stretched at a speed of 200 mm/min to create a stress-strain curve. The tensile modulus of the release liner or adjacent layer 4 alone was calculated by determining the slope of the stress-strain curve at two points of strain of 0.05% and 0.25%.

The tensile elastic modulus E2 of the laminated sample was calculated in the same manner as the calculation of the tensile elastic modulus E1 of the sample described above. In the tensile test of the laminated sample, the tensile elastic modulus of the adhesive layer 3 (for reference, the storage shear elastic modulus G' of the adhesive layer 3 at 25 ° C. in Example 1 is 0.03 MPa) is the same as that of the adjacent layer 4 only. Since it is very small compared to the tensile modulus E1, it can be ignored, and the tensile modulus of only the release liner 2 or the adjacent layer 4 was calculated by the tensile test of the laminated sample described above.

(Relationship values between thickness T0 of adhesive layer 3, thickness T1 and tensile modulus E1 of release liner 2, and thickness T2 and tensile modulus E2 of adjacent layer 4)

The thickness T0 of the adhesive layer 3, the thickness T1 and tensile modulus E1 of the release liner 2, and the thickness T2 and tensile modulus E2 of the adjacent layer 4 are obtained from the left side of the above equation (E1×E2×(T1+T2)/[ T0 ^1/2 × 100,000]).

(Shear storage modulus G' of adhesive layer 3)
The shear storage modulus G' of the adhesive layer 3 was determined by dynamic viscoelasticity measurement.

First, a required number of samples for measurement were produced for each adhesive layer 3 . Specifically, first, a plurality of sheet pieces cut out from the adhesive layer 3 were adhered to prepare a sample sheet having a thickness of about 1.5 mm. Next, this sheet was punched out to obtain cylindrical pellets (diameter 7.9 mm) as samples for measurement.

Then, the measurement sample was fixed to a parallel plate jig with a diameter of 7.9 mm using a dynamic viscoelasticity measuring device (product name: "Advanced Rheometric Expansion System (ARES)", manufactured by Rheometric Scientific) and then moved. A viscoelasticity measurement was performed. In the dynamic viscoelasticity measurement, the measurement mode was the shear mode, the measurement temperature range was -40°C to 100°C, the temperature increase rate was 5°C/min, and the frequency was 1 Hz. The shear storage modulus at 25°C was read from the measurement results.

1 Optical adhesive sheet 2 Release liner 3 Adhesive layer 4 Adjacent layer 4A Second release liner 10 Optical adhesive sheet 11 Image display device member 12 Image display device member 21 Offset portion 25 Concave portion 41 Second offset portion 100 Sample 101 First portion 102 Second part 105 Base D Deflection amount E1 Tensile modulus (release liner)
E2 tensile modulus (adjacent layer)
G' shear storage modulus (adhesive layer)
H indentation hardness (adhesive layer)
OL offset amount (release liner)
OL2 second offset amount (adjacent layer)
P product (release liner)
P2 stack (adjacent layer)

Claims (13)

A release liner and an adhesive layer are provided in order toward one side in the thickness direction,
The maximum length L of the adhesive layer in the orthogonal direction orthogonal to the thickness direction is 200 mm or more,
The optical adhesive sheet, wherein the release liner is larger than the adhesive layer when viewed in the thickness direction and includes the adhesive layer. 2. The optical pressure-sensitive adhesive sheet according to claim 1, wherein the deflection amount D measured by the following deflection test is 7 mm or less.
Flexure test: The optical pressure-sensitive adhesive sheet is shaped to a size of 100 mm in length and 25 mm in width to prepare a sample. A table having a top surface and a height of 50 mm or more is prepared. A first portion having a length of 50 mm including one edge in the longitudinal direction of the sample is fixed to the upper surface, and a second portion having a length of 50 mm including the other edge in the longitudinal direction of the sample is fixed to the side from one edge of the upper surface. protrude in the direction of After that, it is left at 23° C. for 5 minutes. After that, the amount of movement of one edge of the protruding sample downward from the upper surface is obtained as the amount of deflection D. FIG. 3. The optical pressure-sensitive adhesive sheet according to claim 1 or 2, wherein an area P, which is the product of the offset amount and the thickness of the release liner defined below, is 90×10 ⁻⁸ m ² or more.
Offset amount: length (mm) of the offset portion of the release liner that is displaced from the adhesive layer when viewed in the thickness direction
The thickness: the average thickness (μm) at three points in the offset portion further comprising an adjacent layer adjacent to the adhesive layer on the opposite side of the release liner in the thickness direction;
3. The optical pressure-sensitive adhesive sheet according to claim 2, wherein the release liner, the pressure-sensitive adhesive layer, and the adjacent layer satisfy the following formula [1].
E1×E2×(T1+T2)/[T0 ^1/2 ×100,000]≧2,500
[1]
E1: Tensile modulus (MPa) of the release liner at 23°C
E2: Tensile modulus (MPa) of the adjacent layer at 23°C
T1: Thickness of the release liner (μm)
T2: thickness of the adjacent layer (μm)
T0: Thickness of the adhesive layer (μm) 5. The optical adhesive sheet according to claim 4, wherein said adjacent layer is a second release liner. 6. The optical adhesive sheet according to claim 5, wherein the second release liner is larger than and includes the adhesive layer when viewed in the thickness direction. 7. The optical pressure-sensitive adhesive sheet according to claim 6, wherein the area P2, which is the product of the offset amount and the thickness of the second release liner defined below, is 90×10 ⁻⁸ m ² or more.
Second offset amount: Length (mm) of the second offset portion of the second release liner that is displaced from the adhesive layer when viewed in the thickness direction
Thickness: average thickness (μm) at three points in the second offset portion 5. The optical pressure-sensitive adhesive sheet according to claim 4, wherein the adjacent layer is a member for an image display device. 9. The optical adhesive sheet according to claim 8, wherein the peripheral edge of the member for image display device matches the peripheral edge of the adhesive layer when viewed in the thickness direction. One surface of the release liner in the thickness direction has a recess that is recessed toward the other side in the thickness direction around the peripheral edge of the adhesive layer,
10. The optical pressure-sensitive adhesive sheet according to any one of claims 1 to 9, wherein the recesses have a depth of 30 [mu]m or less. The optical pressure-sensitive adhesive sheet according to any one of claims 1 to 10, wherein the pressure-sensitive adhesive layer has an indentation hardness H of 10 kPa or less at 23°C. The optical pressure-sensitive adhesive sheet according to any one of claims 1 to 11, wherein the pressure-sensitive adhesive layer has a shear storage modulus G' of 100 kPa or less at 25°C. An optical adhesive sheet provided in an image display device and comprising the adhesive layer,
13. The image display device according to any one of claims 1 to 12, wherein the image display device comprises the adhesive layer and a pair of image display device members respectively formed on one surface and the other surface of the optical adhesive sheet in the thickness direction. The optical pressure-sensitive adhesive sheet according to any one of the items.