JP2022182619A - Optical element, laminate, display device, and manufacturing method of optical element - Google Patents

Abstract

To provide an optical element, in which when a polarizing plate obtained by combining with a polarizer is applied to a display element, well-defined black at visual recognition time from a front direction in a black display is given, a laminate, a display device, and a manufacturing method of the optical element.SOLUTION: An optical element comprises: an optical anisotropy layer; and an optical isotropic member. In the optical element, the optical anisotropy layer and the optical isotropic member contact to each other, an absolute value of a difference between an average refractive index of the optical anisotropy layer and a refractive index of the optical isotropic member is less than or equal to 0.08, and the optical isotropic member has a protrusion part that protrudes to an opposite side of an optical anisotropy layer side.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to an optical element, a laminate, a display device, and a method for manufacturing an optical element.

As a display device for displaying images, for example, an organic electroluminescence (organic EL) display device for displaying an image by causing a light-emitting layer to emit light is known.
A display device such as an organic EL display device may include various optical elements. an optical sheet having a plurality of first portions extending in a second direction intersecting the first direction, and second portions alternately arranged along the first direction and the first portions, and the like are included in the display device. is

JP 2020-187261 A

On the other hand, when the present inventors examined the characteristics of the display device described in Patent Document 1, when black display was performed and viewed from the front direction, reflected light was confirmed, and the black tightness was not necessarily sufficient. We have found that improvements are needed.

An object of the present invention is to provide an optical element in which, when a polarizing plate obtained in combination with a polarizer is applied to a display element, black display is excellent in tightness of black when viewed from the front direction.
Another object of the present invention is to provide a laminate, a display device, and a method for manufacturing an optical element.

As a result of earnestly studying the problems of the prior art, the inventors of the present invention have found that the above problems can be solved by the following configuration.

(1) an optically anisotropic layer;
an optically isotropic member;
the optically anisotropic layer and the optically isotropic member are in contact,
the absolute value of the difference between the average refractive index of the optically anisotropic layer and the refractive index of the optically isotropic member is within 0.08;
The optically isotropic member is an optical element having convex portions protruding on the side opposite to the optically anisotropic layer.
(2) The optical element according to (1), wherein both the optically anisotropic layer and the optically isotropic member are formed using a liquid crystal compound.
(3) The optical element according to (1) or (2), wherein the optically anisotropic layer and the optically isotropic member are both formed using the same liquid crystal compound.
(4) The optical element according to any one of (1) to (3), wherein the optically anisotropic layer is a λ/4 plate.
(5) The optical element according to any one of (1) to (4), in which a plurality of convex portions are arranged periodically.
(6) The optical element according to any one of (1) to (5), wherein the distance between the plurality of convex portions is 0.2 to 20 μm.
(7) The optical element according to any one of (1) to (6), wherein the convex portions are arranged in dots or stripes.
(8) According to any one of (1) to (7), the width of the convex portion gradually increases from the side opposite to the optically anisotropic layer side of the convex portion toward the optically anisotropic layer side. optics.
(9) A laminate comprising the optical element according to any one of (1) to (8) and an adhesive layer disposed on the optical isotropic member side of the optical element.
(10) having a polarizer, the optical element according to any one of (1) to (8), and a display element in this order;
A display device in which an optically anisotropic layer in an optical element is arranged on the polarizer side.
(11) Step 1 of forming a composition layer containing a liquid crystal compound having a polymerizable group on a substrate;
Step 2 of heat-treating the composition layer to orient the liquid crystal compound in the composition layer;
After step 2, step 3 of irradiating the composition layer with light under conditions of an oxygen concentration of 1% by volume or more;
A step 4 of pressing a mold having an uneven structure on its surface against the surface of the composition layer opposite to the substrate side to transfer the uneven structure of the mold to the composition layer;
An optical element having an optically anisotropic layer and an optically isotropic member having convex portions projecting from the substrate side to the side opposite to the optically anisotropic layer side is provided by subjecting the composition layer to a curing treatment. and a step 5 of forming;
A method for manufacturing an optical element, which satisfies any one of requirements 1 to 4 described below.

ADVANTAGE OF THE INVENTION According to this invention, when the polarizing plate obtained by combining with a polarizer is applied to a display element, the optical element which has favorable black density at the time of viewing from the front direction in a black display can be provided.
Further, according to the present invention, it is possible to provide a laminate, a display device, and a method for manufacturing an optical element.

1 shows a schematic cross-sectional view of one embodiment of an optical element of the present invention; FIG. 2 shows a plan view of part of the optical element shown in FIG. 1; FIG. Fig. 2 shows a plan view of another embodiment of the optical element of the present invention; Fig. 3 shows a schematic cross-sectional view of another embodiment of the optical element of the present invention; Figure 5 shows a plan view of part of the optical element shown in Figure 4; FIG. 4 is a cross-sectional view of a composition layer for explaining step 2; FIG. 4 is a cross-sectional view of a composition layer for explaining step 3; FIG. 10 is a cross-sectional view of a composition layer for explaining step 4; FIG. 10 is a cross-sectional view of a composition layer for explaining step 4; It is a sectional view for explaining an optical element. FIG. 4 is a cross-sectional view of a composition layer for explaining step 2; FIG. 4 is a cross-sectional view of a composition layer for explaining step 3; FIG. 4 is a cross-sectional view of a composition layer for explaining heat treatment; A graph plotting the relationship between helical twisting power (HTP) (μm ⁻¹ )×concentration (mass %) and light irradiation dose (mJ/cm ² ) for each of chiral agent A and chiral agent B. It is a schematic diagram. 2 is a schematic diagram of a graph plotting the relationship between the weighted average helical induced force (μm ⁻¹ ) and the light irradiation amount (mJ/cm ² ) in a system in which chiral agent A and chiral agent B are used in combination. FIG. FIG. 4 is a cross-sectional view of a composition layer for explaining step 3; It is a sectional view for explaining an optical element.

The present invention will be described in detail below. In this specification, the numerical range represented by "-" means a range including the numerical values before and after "-" as lower and upper limits. First, the terms used in this specification will be explained.

The slow axis is defined at a wavelength of 550 nm unless otherwise specified.

In the present invention, Re(λ) and Rth(λ) represent in-plane retardation and thickness direction retardation at wavelength λ, respectively. Unless otherwise specified, the wavelength λ is 550 nm.
In the present invention, Re(λ) and Rth(λ) are values measured at wavelength λ with AxoScan (manufactured by Axometrics). By entering the average refractive index ((nx+ny+nz)/3) and film thickness (d (μm)) in AxoScan,
Slow axis direction (°)
Re(λ)=R0(λ)
Rth(λ)=((nx+ny)/2−nz)×d
is calculated.
Note that R0(λ), which is displayed as a numerical value calculated by AxoScan, means Re(λ).

In this specification, the refractive indices nx, ny, and nz are measured using an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) using a sodium lamp (λ=589 nm) as the light source. In addition, when measuring the wavelength dependence, it can be measured by using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in combination with an interference filter.
Also, the values in the polymer handbook (JOHN WILEY & SONS, INC) and various optical film catalogs can be used. Examples of average refractive index values of main optical films are as follows: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).

The term "light" used herein means actinic rays or radiation, and includes, for example, the emission line spectrum of mercury lamps, far ultraviolet rays represented by excimer lasers, extreme ultraviolet rays (EUV light: Extreme Ultraviolet), X-rays, ultraviolet rays, and electron beam (EB). Among them, ultraviolet rays are preferable.

As used herein, "visible light" refers to light between 380 and 780 nm. In this specification, the measurement wavelength is 550 nm unless otherwise specified.

In the optical element of the present invention, the optically anisotropic layer and the optically isotropic member are arranged in contact with each other, and since the refractive index difference between the two is small, interface reflection between the two is suppressed. , as a result, the effect of the present invention is obtained.
In addition, when the polarizing plate obtained by combining the optical element of the present invention and a polarizer is applied to a display element, the black density when viewed from the front direction in black display is more excellent, hereinafter simply referred to as "the present invention. It is said that the effect of
As will be described later, when the protrusions have a predetermined structure and arrangement (for example, when the protrusions have a predetermined size, or when the intervals between the protrusions are within a predetermined range), the light-emitting element of the present invention When a polarizing plate obtained by combining with a polarizer is applied to a display element, generation of bluish tint when viewed from an oblique direction in white display is suppressed. Hereinafter, further suppression of the occurrence of bluish tinge when viewed from an oblique direction in white display is also simply referred to as “more suppression of the occurrence of bluishness”.

<Optical element>
One embodiment of the optical element of the present invention will be described below with reference to the drawings.
FIG. 1 shows a schematic cross-sectional view of one embodiment of the optical element of the present invention. FIG. 2 shows a plan view of part of the optical element shown in FIG. Note that the plan view is a view of part of the optical element in FIG. 1 as seen from above. 1 is a cross-sectional view taken along the line AA in FIG. 2. FIG. For the sake of explanation, in FIG. 2, the horizontal direction on the drawing is the X-axis direction, and the vertical direction is the Y-axis direction.
The optical element 10A has an optically anisotropic layer 12 and an optically isotropic member 14A. The optically anisotropic layer 12 and the optically isotropic member 14A are in direct contact. A concave-convex structure is formed on the surface of the optically isotropic member 14A opposite to the optically anisotropic layer 12 side, and a plurality of protrusions projecting to the side opposite to the optically anisotropic layer 12 side are formed. Dot-shaped convex portions 16A are formed. More specifically, the optical isotropic member 14A has a base portion 18A and dot-shaped convex portions 16A arranged on the base portion 18A. The convex portion 16A has a truncated cone shape, and the convex portion 16A has a circular shape in plan view. There are a plurality of convex portions 16A, and the plurality of convex portions 16A are arranged in a hexagonal close-packed manner. That is, the plurality of convex portions 16A are arranged periodically. The base portion 18A is continuously connected along the plane direction and is in contact with the optically anisotropic layer 12 .

Although only eight convex portions 16A are shown in FIG. 2, FIG. 2 is a plan view of a part of the optical element, and eight or more convex portions 16A are formed in the optical element. .
In FIG. 1, the convex portion 16A has a truncated cone shape, but the present invention is not limited to this aspect, and may have, for example, a hemispherical shape, a conical shape, an inverted truncated cone shape, or a truncated pyramid shape. Note that the inverted truncated cone shape corresponds to a mode in which the width of the upper base is larger than the width of the lower base, unlike the mode in FIG.
In FIG. 1, the convex portion 16A has a circular shape in plan view, but the present invention is not limited to this aspect, and may have, for example, a polygonal shape, an elliptical shape, or an irregular shape.
In FIG. 1, the convex portion 16A has a trapezoidal shape in which the upper base is smaller than the lower base when viewed in cross section. That is, the width of the convex portion 16A gradually increases from the side opposite to the optically anisotropic layer 12 side of the convex portion 16A toward the optically anisotropic layer 12 side (toward the direction of the white arrow in the figure). is doing. More specifically, as shown in FIG. 2, the width WA1 (diameter of the upper base) of the upper base of the convex portion 16A is smaller than the width WA2 (diameter of the lower base) of the lower base of the convex portion 16A. The width of 16A gradually increases from the top to the bottom.
As for the cross-sectional shape of the convex portion 16A, the leg portions of the trapezoidal shape may be curved lines instead of straight lines.
When the convex portion 16A has the structure as described above, the occurrence of bluish tint is further suppressed.

The width WA1 of the upper base of the truncated cone-shaped protrusion 16A shown in FIG. 0.2 to 20.0 μm is more preferable, and 0.2 to 5.0 μm is even more preferable in terms of suppression.
The width WA2 of the lower base of the truncated cone-shaped protrusion 16A is not particularly limited, and is preferably 0.1 to 20.0 μm from the viewpoint of the effect of the present invention being more excellent, and from the viewpoint of further suppressing the occurrence of bluish tint. , 0.2 to 20.0 μm, more preferably 0.2 to 5.0 μm.
As described above, the width WA1 of the upper base of the protrusion 16A is preferably smaller than the width WA2 of the lower base, and the width of the protrusion 16A gradually increases from the upper base toward the lower base. preferable.

The height HA1 of the convex portion 16A is not particularly limited, and is preferably 0.1 to 20.0 μm in terms of the effect of the present invention, and 0.2 to 20 μm in terms of further suppressing the occurrence of bluish tint. 0 μm is more preferred, and 0.2 to 5.0 μm is even more preferred.
The thickness HA2 of the base portion 18A (thickness obtained by subtracting the height of the convex portion 16A from the total thickness of the optical isotropic member 14A) is not particularly limited, and is from 0.1 to 20 in the point that the effect of the present invention is more excellent. It is preferably 0.0 μm, more preferably 0.2 to 20.0 μm, even more preferably 0.2 to 5.0 μm, in terms of further suppressing the occurrence of bluish tint.
The period PA (interval between adjacent protrusions) of the protrusions 16A is not particularly limited, and is preferably 0.1 to 20.0 μm from the viewpoint of more excellent effects of the present invention, which further suppresses the occurrence of bluish tint. 0.2 to 5.0 μm is more preferable, and 0.2 to 5.0 μm is even more preferable.
The ratio of the height HA1 of the protrusions 16A to the period PA of the protrusions 16A is not particularly limited, and is preferably 0.005 to 200, more preferably 0.01 to 100, from the viewpoint that the effects of the present invention are more excellent. 0.1 to 10 are more preferred.

In FIG. 1, the truncated cone-shaped protrusions 16A are arranged in a hexagonal close-packed configuration, but the present invention is not limited to this embodiment. may be arranged in a square lattice or may be arranged randomly.

In addition, in FIG. 1, the aspect of the convex portion 16A having a truncated cone shape has been described, but the present invention is not limited to this aspect, and the convex portions may be arranged in stripes. This aspect will be described in detail below.
FIG. 4 shows a schematic cross-sectional view of another example of the optical element of the present invention. FIG. 5 shows a plan view of part of the optical element shown in FIG. Note that the plan view is a view of part of the optical element seen from above in FIG. 4 . 4 is a cross-sectional view taken along line BB in FIG. For the sake of explanation, in FIG. 5, the horizontal direction on the drawing is the X-axis direction, and the vertical direction is the Y-axis direction.

The optical element 10B has an optically anisotropic layer 12 and an optically isotropic member 14B. The optically anisotropic layer 12 and the optically isotropic member 14B are in direct contact. A concave-convex structure is formed on the surface of the optically isotropic member 14B opposite to the optically anisotropic layer 12 side, and convex portions 16B are arranged in stripes. More specifically, the optically isotropic member 14B has a base portion 18B and convex portions 16B arranged in stripes on the base portion 18B. The protrusions 16B extend in the Y direction and are periodically arranged in a direction (X direction) perpendicular to the extending direction. The base portion 18B is continuously connected along the plane direction and is in contact with the optically anisotropic layer 12 .

Although only three convex portions 16B are shown in FIG. 5, FIG. 5 is a plan view of a part of the optical element, and three or more convex portions 16B are formed in the optical element. .
As shown in FIG. 4, the convex portion 16B has a trapezoidal shape in a cross section orthogonal to the extending direction, but the present invention is not limited to this aspect, and the convex portion 16B may have a semicircular shape.
In FIG. 4, the convex portion 16B has a trapezoidal shape in which the upper base is smaller than the lower base when viewed in cross section. That is, the width of the convex portion 16B gradually increases from the side opposite to the optically anisotropic layer 12 side of the convex portion 16B toward the optically anisotropic layer 12 side (toward the direction of the white arrow in the figure). is doing. More specifically, as shown in FIG. 5, the width WB1 (diameter of the upper base) of the upper base of the convex portion 16B is smaller than the width WB2 (diameter of the lower base) of the lower base of the convex portion 16B. The width of 16B gradually increases from the upper base to the lower base.
As for the cross-sectional shape of the projection 16B, the legs of the trapezoidal shape may be curved lines instead of straight lines.
When the convex portion 16B has the structure as described above, the occurrence of bluish tint is further suppressed.

The width WB1 of the upper base of the convex portion 16B having a trapezoidal cross section shown in FIG. 5 is not particularly limited, and is preferably in the same range as the width WA1 described above.
The width WB2 of the lower base of the truncated conical protrusion 16B is not particularly limited, and is preferably in the same range as the width WB2 described above.
As described above, the width WB1 of the upper base of the protrusion 16B is preferably smaller than the width WB2 of the lower base, and the width of the protrusion 16B gradually increases from the upper base toward the lower base. preferable.
The height HB1 of the convex portion 16B is not particularly limited, and is preferably in the same range as the height HA1 described above.
The thickness HB2 of the base portion 18B (thickness obtained by subtracting the height of the convex portion 16B from the total thickness of the optical isotropic member 14B) is not particularly limited, and is preferably in the same range as the height HA2 described above.
The period PB of the projections 16B is not particularly limited, and is preferably within the same range as the period PB described above.
The ratio of the height HB1 of the projections 16A to the period PB of the projections 16A is not particularly limited, and is preferably within the same range as the ratio of the height HA1 to the period PA described above.

In FIGS. 1 and 4, an aspect with the base portion 18A and the base portion 18B is described, but the present invention is not limited to this aspect, and the optical isotropic member may be composed only of a plurality of convex portions. good.

In the optical element of the present invention, the optically anisotropic layer and the optically isotropic member are in contact with each other. In particular, it is preferable that the optically anisotropic layer and the optically isotropic member are in contact along the thickness direction of the optical element. It is preferable that one of the two main surfaces of the member is in contact with the main surface of the two main surfaces of the optically isotropic member on which the concave-convex structure is not arranged.

In the optical element of the present invention, the absolute value of the difference between the average refractive index of the optically anisotropic layer and the refractive index of the optically isotropic member is within 0.08, and the effects of the present invention are more excellent. , preferably within 0.06, more preferably within 0.04. Although the lower limit is not particularly limited, 0 can be mentioned.
The average refractive index of the optically anisotropic layer is the refractive index in the direction in which the refractive index in the in-plane direction of the optically anisotropic layer is maximized, and the direction orthogonal to the direction in which the refractive index in the in-plane direction is maximized. is the arithmetic mean value of the refractive index at .
As a method for measuring the average refractive index of the optically anisotropic layer, for example, the optically isotropic member of the optical element is removed by etching to expose the optically anisotropic layer, and a polarizer is used. Using an Abbe refractometer, the refractive index in the direction in which the refractive index in the in-plane direction of the optically anisotropic layer is maximized and the refractive index in the direction orthogonal to the direction in which the refractive index in the in-plane direction is maximized are determined. The average refractive index of the optically anisotropic layer is obtained by taking the arithmetic average of the measured values.
Further, as a method for measuring the refractive index of the optically isotropic member, a part of the optically isotropic member is scraped off to form a powder, and the obtained powder is immersed in a solvent having a different refractive index. The refractive index is determined by observing the Becke line (the so-called Becke line method).
The above average refractive index and refractive index are refractive indices at a measurement temperature of 23° C. and a wavelength of 589 nm.
As will be described later, when the optically anisotropic layer has a plurality of regions in which the alignment state of the liquid crystal compound is different along the thickness direction, the average refractive index of the region in contact with the optically isotropic member is measured, It is the average refractive index of the optically anisotropic layer.

The method for adjusting the range of the absolute value of the difference between the average refractive index of the optically anisotropic layer and the refractive index of the optically isotropic member is not particularly limited. and the type of material constituting the optically isotropic member, and a method of forming the optically anisotropic layer and the optically isotropic member using the same material.
As will be described later, both the optically anisotropic layer and the optically isotropic member may be formed using a liquid crystal compound. Therefore, in order to keep the absolute value of the difference between the average refractive index of the optically anisotropic layer and the refractive index of the optically isotropic member within the above range, the optically anisotropic layer and the optically isotropic member are preferably layers formed using the same liquid crystal compound.

The optically anisotropic layer and the optically isotropic member are described in more detail below.

<Optical anisotropic layer>
An optically anisotropic layer is a layer exhibiting optical anisotropy. Optically anisotropic layers include, for example, layers in which at least two of nx, ny, and nz are different. Note that nx represents the refractive index in the direction (in-plane direction) perpendicular to the thickness direction of the optically anisotropic layer, which gives the maximum refractive index. ny represents the refractive index in the in-plane direction of the optically anisotropic layer and in the direction orthogonal to the nx direction. nz represents the refractive index in the thickness direction of the optically anisotropic layer.
Examples of the optically anisotropic layer include a λ/4 plate, a λ/2 plate, a layer having a fixed cholesteric liquid crystal phase, a layer having a fixed hybrid alignment phase, and the like. A λ/4 plate is preferable in that it is superior to the λ/4 plate.

A λ/4 plate is a plate that has the function of converting linearly polarized light of a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). More specifically, the plate exhibits an in-plane retardation Re of λ/4 (or an odd multiple thereof) at a predetermined wavelength λnm.
The in-plane retardation (Re (550)) of the λ / 4 plate at a wavelength of 550 nm may have an error of about 25 nm around the ideal value (137.5 nm), for example, 110 to 160 nm. It is preferably from 120 to 150 nm, more preferably from 120 to 150 nm.
A λ/2 plate is an optically anisotropic film in which the in-plane retardation Re(λ) at a specific wavelength λnm satisfies Re(λ)≈λ/2. This formula should be achieved at any wavelength (eg, 550 nm) in the visible light region. Among others, it is preferable that the in-plane retardation Re(550) at a wavelength of 550 nm satisfies the following relationship.
210 nm≦Re(550)≦300 nm

The material constituting the optically anisotropic layer is not particularly limited, and examples thereof include liquid crystal compounds and polymers. Liquid crystal compounds are preferred because the effects of the present invention are more excellent. In particular, the optically anisotropic layer is preferably a layer formed using a liquid crystal compound, and more preferably a layer formed using a liquid crystal compound having a polymerizable group.

The type of liquid crystal compound is not particularly limited. In general, liquid crystal compounds can be classified into a rod-like type (rod-like liquid crystal compound) and a disk-like type (discotic liquid crystal compound) according to their shape. Furthermore, liquid crystal compounds can be classified into low-molecular-weight types and high-molecular-weight types. Polymers generally refer to those having a degree of polymerization of 100 or more (polymer physics, phase transition dynamics, Masao Doi, p. 2, Iwanami Shoten, 1992). Although any liquid crystal compound can be used in the present invention, a rod-like liquid crystal compound or a discotic liquid crystal compound is preferably used, and a rod-like liquid crystal compound is more preferably used. Two or more rod-like liquid crystal compounds, two or more discotic liquid crystal compounds, or a mixture of a rod-like liquid crystal compound and a discotic liquid crystal compound may be used.
The rod-like liquid crystal compound includes, for example, the liquid crystal compounds described in claim 1 of JP-A-11-513019 and paragraphs 0026 to 0098 of JP-A-2005-289980.
Discotic liquid crystal compounds include, for example, liquid crystal compounds described in paragraphs 0020 to 0067 of JP-A-2007-108732 and paragraphs 0013 to 0108 of JP-A-2010-244038.

The liquid crystal compound preferably has a polymerizable group. That is, the liquid crystal compound is preferably a polymerizable liquid crystal compound. When the liquid crystal compound has a polymerizable group, the alignment state of the liquid crystal compound can be easily fixed by the curing treatment described below.
The type of polymerizable group possessed by the liquid crystal compound is not particularly limited, and is preferably a functional group capable of addition polymerization reaction, more preferably a polymerizable ethylenically unsaturated group or a ring polymerizable group, (meth) acryloyl group, vinyl group. , a styryl group, or an allyl group are more preferred.
Although the number of polymerizable groups possessed by the liquid crystal compound is not particularly limited, it is preferably two or more. Although the upper limit is not particularly limited, it is often 10 or less.

The liquid crystal compound may be a liquid crystal compound exhibiting either forward wavelength dispersion or reverse wavelength dispersion, preferably a liquid crystal compound exhibiting reverse wavelength dispersion, having two or more polymerizable groups, and exhibiting reverse wavelength dispersion. is more preferred.
As used herein, the term "liquid crystal compound exhibiting reverse wavelength dispersion" refers to the in-plane retardation (Re) value at a specific wavelength (visible light range) of an optically anisotropic film produced using this compound. In some cases, it means a substance that satisfies the relationship of the following formulas (A) and (B).
Formula (A) Re(450)/Re(550)<1.00
Formula (B) Re(650)/Re(550)≧1.00
Re(450) represents the in-plane retardation of the optically anisotropic film at a wavelength of 450 nm, Re(550) represents the in-plane retardation of the optically anisotropic film at a wavelength of 550 nm, and Re(650) represents the optical difference at a wavelength of 650 nm. It represents the in-plane retardation of an anisotropic film.
As used herein, the term "liquid crystal compound exhibiting normal wavelength dispersion" refers to the in-plane retardation (Re) value at a specific wavelength (visible light range) of an optically anisotropic film produced using this compound. In some cases, it means a substance that satisfies the following formulas (C) and (D).
Formula (C) Re(450)/Re(550)≧1.00
Formula (D) Re(650)/Re(550)<1.00

As described above, the optically anisotropic layer is preferably a layer formed using a liquid crystal compound having a polymerizable group, and is a layer formed by fixing the alignment state of the liquid crystal compound having a polymerizable group. is more preferable.
The orientation state that the liquid crystal compound having a polymerizable group can take is not particularly limited. orientation in which the angle changes continuously) and tilted orientation (orientation in which the tilt angle of the liquid crystal compound is constant from one surface to the other surface). The twisted alignment refers to an alignment state in which the liquid crystal compound is twisted around the thickness direction as the axis of rotation. It corresponds to hybrid orientation. In this specification, the twisted alignment corresponds to a mode in which the twist angle of the liquid crystal compound is less than 360°, and the cholesteric alignment corresponds to a mode in which the liquid crystal compound has a twist angle of 360° or more.
The "fixed" state is the most typical and preferable mode in which the orientation of the liquid crystal compound is maintained. Specifically, the layer has no fluidity in the temperature range of usually 0 to 50° C., and -30 to 70° C. under more severe conditions, and can be oriented by an external field or force. It is more preferable to be in a state in which the fixed alignment form can be stably maintained without causing any change.

The optically anisotropic layer may have a plurality of regions in which the alignment state of the liquid crystal compound is different along the thickness direction. In particular, it is preferable that the optically anisotropic layer has a plurality of regions in which the alignment state of the liquid crystal compound is different along the thickness direction, and the liquid crystal compound in each region is fixed.
For example, the optically anisotropic layer may have, along the thickness direction, a region in which the homogeneous alignment of the liquid crystal compound is fixed and a region in which the twisted alignment of the liquid crystal compound is fixed. good.

Although the thickness of the optically anisotropic layer is not particularly limited, it is preferably 0.1 to 10.0 μm, more preferably 0.5 to 5.0 μm.

A method for producing the optically anisotropic layer will be described in detail later.

<Optical isotropic member>
An optically isotropic member is a layer exhibiting optical isotropy.
A method for identifying the optically isotropic member is as follows.
First, the optical isotropic member, which is the object to be measured, is cut along one direction (hereinafter also referred to as “direction D1”) in the plane of the optical isotropic member to obtain a thin film (about 2 μm thick). Section sample 1 is cut. Assuming that the direction D1 is the x-direction, the in-plane direction perpendicular to the direction D1 is the y-direction, and the thickness direction of the object to be measured is the z-direction, the principal plane of the section sample 1 corresponds to the xz-plane of the object to be measured. do. In addition, the object to be measured is cut along an in-plane direction perpendicular to the direction D1 to cut out a slice sample 2 in the form of a thin film (thickness of about 2 μm). The principal plane of the section sample 2 corresponds to the yz plane of the object to be measured. Furthermore, the object to be measured is cut along an in-plane direction (hereinafter also referred to as "direction D2") that forms 45 degrees with respect to the direction D1, and a thin film (about 2 μm thick) section sample 3 is obtained. break the ice. Furthermore, the object to be measured is cut along an in-plane direction perpendicular to the direction D2 to cut out a thin film-like (thickness of about 2 μm) slice sample 4 .
Next, each of the obtained section samples (section samples 1 to 4) is fixed with an adhesive with one of the two main surfaces facing the cover glass, and a polarizing microscope is used under crossed Nicol conditions. Observe each section sample at , and measure the retardation per 1 μm thickness by the Senarmont method using light with a wavelength of 546 nm. Assume that the object is optically isotropic, in other words, the object to be measured is an optically isotropic member.
As a specific measurement method for the Senarmont method, first, a GIF filter (wavelength 546 nm) is set with the polarizer and analyzer of a polarizing microscope at 0° (crossed Nicols), and the portion of the section sample to be observed. Rotate the coverslip with the sectioned sample so that the is the brightest. After that, the Senarmont compensator is set, the analyzer is rotated, and the rotation angle θ of the analyzer at which the part of the section sample to be observed becomes darkest is read. Retardation (Re) is calculated by the formula Re=(546 nm×θ)/180.

Materials constituting the optically isotropic member are not particularly limited, and examples thereof include liquid crystal compounds and polymers. Liquid crystal compounds are preferred because the effects of the present invention are more excellent. In particular, the optically isotropic member is preferably a layer formed using a liquid crystal compound, and more preferably a layer formed using a liquid crystal compound having a polymerizable group.
The type of liquid crystal compound used for forming the optically isotropic member is the same as the type of liquid crystal compound used for forming the optically anisotropic layer.
A method of forming an optically isotropic member using a liquid crystal compound includes a method of fixing a liquid crystal compound in an isotropic phase state, as described later.

As described above, the optically isotropic member is preferably a member formed using a liquid crystal compound having a polymerizable group. is more preferable.

The thickness of the optical isotropic member (the distance from the surface of the optical isotropic member having no convex portion to the tip of the convex portion) is not particularly limited, but is preferably 0.1 to 40 μm, more preferably 0.4 to 10 μm. preferable.

A method for manufacturing the optically isotropic member will be described in detail later.

<Method for Manufacturing Optical Element>
The method for producing the optical element of the present invention is not particularly limited, and can be produced by combining known methods.
Among them, a production method that includes the following steps 1 to 5 and satisfies any one of requirements 1 to 4 is preferable in that the optical element of the present invention can be produced efficiently.
Step 1: Step of forming a composition layer containing a liquid crystal compound having a polymerizable group on a substrate Step 2: Heating the composition layer to align the liquid crystal compound in the composition layer Step 3: Step After 2, the composition layer is irradiated with light under conditions of an oxygen concentration of 1% by volume or more Step 4: A mold having an uneven structure on the surface is placed on the opposite side of the composition layer from the substrate side. Step 5: Heat treatment is applied to the composition layer to harden the liquid crystal compound, and the optically anisotropic layer and the Step requirement 1 for forming an optical element having an optically isotropic member having convex portions projecting on the side opposite to the optically anisotropic layer side: Step 4 is performed by removing the liquid crystal phase of the composition constituting the composition layer. It is carried out under heating conditions equal to or higher than the phase transition temperature to the isotropic phase.
Requirement 2: Step 5 is carried out under heating conditions equal to or higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer.
Requirement 3: Between the steps 3 and 4, the method further includes a step 6 of heating the composition layer to a temperature equal to or higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer.
Requirement 4: Between the steps 4 and 5, the method further includes a step 7 of heating the composition layer to a temperature equal to or higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer.
Steps 1 to 5 are described in detail below. In addition, in the following description, first, a mode that satisfies Requirement 1 will be described.

(Step 1)
Step 1 is a step of forming a composition layer containing a liquid crystal compound having a polymerizable group on a substrate. By carrying out this step, a composition layer to be subjected to light irradiation treatment, which will be described later, is formed.
In the following, first, the materials used in this process will be described in detail, and then the procedure of the process will be described in detail.

[Liquid crystal compound having a polymerizable group]
The composition layer contains a liquid crystal compound having a polymerizable group.
The description of the liquid crystal compound having a polymerizable group is as described above.

Although the content of the liquid crystal compound in the composition layer is not particularly limited, it is preferably 60% by mass or more, more preferably 70% by mass or more, based on the total mass of the composition layer in terms of easy control of the alignment state of the liquid crystal compound. more preferred. Although the upper limit is not particularly limited, it is preferably 99% by mass or less, more preferably 97% by mass or less.

[Other ingredients]
The composition layer may contain components other than the liquid crystal compound having a polymerizable group.

The composition layer may contain, for example, a photosensitive chiral agent whose helical inducing force is changed by light irradiation. By including a photosensitive chiral agent in the composition layer, it is possible to form a region in which a twisted or cholesterically oriented liquid crystal compound is fixed, as will be described later.
The helical induction power (HTP) of the chiral agent is a factor that indicates the helical orientation ability represented by the following formula (A).
Formula (A) HTP = 1/(Length of helical pitch (unit: µm) x Concentration of chiral agent with respect to liquid crystal compound (% by mass)) [µm ^-1 ]
The length of the helical pitch refers to the length of the helical structure pitch P (= helical period) of the cholesteric liquid crystal phase, which can be measured by the method described on page 196 of Liquid Crystal Handbook (published by Maruzen Co., Ltd.).

The photosensitive chiral agent whose helical inductive force changes upon irradiation with light (hereinafter also simply referred to as “chiral agent A”) may be liquid crystalline or non-liquid crystalline. Chiral agent A generally contains an asymmetric carbon atom in many cases. The chiral agent A may be an axially asymmetric compound or planar asymmetric compound containing no asymmetric carbon atoms.

The chiral agent A may be a chiral agent whose helical induction force increases or decreases upon irradiation with light. Among them, a chiral agent whose helical inducing force is reduced by light irradiation is preferable.
In this specification, "increase and decrease in helical inducing force" means increase and decrease when the initial helical direction of the chiral agent A (before light irradiation) is assumed to be "positive". Therefore, when the helical induced force continues to decrease due to light irradiation, and the helical direction exceeds 0 and becomes “negative” (that is, the helical direction opposite to the initial (before light irradiation) helical direction is induced) case) also corresponds to “a chiral agent that reduces the helical induced force”.

Examples of the chiral agent A include so-called photoreactive chiral agents. A photoreactive chiral agent is a compound that has a chiral site and a photoreactive site that undergoes a structural change upon irradiation with light and, for example, greatly changes the torsional force of a liquid crystal compound in accordance with the amount of irradiation.
Examples of photoreactive sites that undergo structural changes due to light irradiation include photochromic compounds (Kingo Uchida, Masahiro Irie, Kagaku Kogyo, vol.64, 640p, 1999, Kingo Uchida, Masahiro Irie, Fine Chemicals, vol.28(9), 15p , 1999). Further, the structural change means decomposition, addition reaction, isomerization, racemization, [2+2] photocyclization, dimerization reaction, etc. caused by light irradiation to the photoreactive site, and the structural change is irreversible. There may be. Moreover, as a chiral site, for example, Hiroyuki Nohira, Kagaku Sosetsu, No. 22 Liquid Crystal Chemistry, 73p:1994.

Examples of the chiral agent A include photoreactive chiral agents described in paragraphs 0044 to 0047 of JP-A-2001-159709; optically active compounds described in paragraphs 0019-0043 of JP-A-2002-179669; Optically active compounds described in paragraphs 0020 to 0044 of JP-A-2002-179633, optically active compounds described in paragraphs 0016-0040 of JP-A-2002-179670, and paragraphs 0017-0050 of JP-A-2002-179668 optically active compounds, optically active compounds described in paragraphs 0018 to 0044 of JP-A-2002-180051, optically active isosorbide derivatives described in paragraphs 0016-0055 of JP-A-2002-338575, JP-A-2002-080478 The photoreactive optically active compound described in paragraphs 0023 to 0032 of the publication, the photoreactive chiral agent described in paragraphs 0019 to 0029 of JP-A-2002-080851, and the paragraphs 0022 to 0049 of JP-A-2002-179681 Optically active compounds described, optically active compounds described in paragraphs 0015 to 0044 of JP-A-2002-302487, optically active polyesters described in paragraphs 0015-0050 of JP-A-2002-338668, JP-A-2003-055315 Binaphthol derivatives described in paragraphs 0019 to 0041 of the publication, optically active fulgide compounds described in paragraphs 0008 to 0043 of JP-A-2003-073381, and optically active isosorbide described in paragraphs 0015 to 0057 of JP-A-2003-306490 Derivatives, optically active isosorbide derivatives described in paragraphs 0015 to 0041 of JP-A-2003-306491, optically active isosorbide derivatives described in paragraphs 0015-0049 of JP-A-2003-313187, JP-A-2003-313188 Optically active isomannide derivatives described in paragraphs 0015 to 0057, optically active isosorbide derivatives described in paragraphs 0015 to 0049 of JP-A-2003-313189, optically active polyesters described in paragraphs 0015 to 0052 of JP-A-2003-313292 /amide, optically active compounds described in paragraphs 0012 to 0053 of WO2018/194157, and optically active compounds described in paragraphs 0020 to 0049 of JP-A-2002-179682.

As the chiral agent A, among others, a compound having at least a photoisomerization site is preferable, and a compound having a photoisomerizable double bond as the photoisomerization site is more preferable. As the photoisomerization site having a photoisomerizable double bond, the cinnamoyl site, chalcone site, azobenzene site, or A stilbene moiety is preferred, and a cinnamoyl moiety, a chalcone moiety, or a stilbene moiety is more preferred in terms of low absorption of visible light. The photoisomerization site corresponds to the photoreactive site that undergoes a structural change due to light irradiation as described above.

The chiral agent A preferably has any partial structure selected from a binaphthyl partial structure, an isosorbide partial structure (a partial structure derived from isosorbide), and an isomannide partial structure (a partial structure derived from isomannide). . The binaphthyl partial structure, the isosorbide partial structure, and the isomannide partial structure each intend the following structures.
The part where the solid line and the dashed line in the binaphthyl partial structure are parallel represents a single bond or a double bond. In the structures shown below, * represents a bonding position.

The chiral agent A may have a polymerizable group. The type of the polymerizable group is not particularly limited, preferably a functional group capable of addition polymerization reaction, more preferably a polymerizable ethylenically unsaturated group or a ring-polymerizable group, (meth) acryloyl group, vinyl group, styryl group, Alternatively, an allyl group is more preferred.

As the chiral agent A, a compound represented by Formula (C) is preferred.
Formula (C) RLR
Each R independently represents a group having at least one moiety selected from the group consisting of a cinnamoyl moiety, a chalcone moiety, an azobenzene moiety and a stilbene moiety.
L is a divalent linking group formed by removing two hydrogen atoms from the structure represented by formula (D) (a divalent linking group formed by removing two hydrogen atoms from the above binaphthyl partial structure group), a divalent linking group represented by formula (E) (a divalent linking group consisting of the isosorbide partial structure), or a divalent linking group represented by formula (F) (the isomannide partial structure represents a divalent linking group consisting of
In Formula (E) and Formula (F), * represents a bonding position.

In step 1, two or more chiral agents A may be used, or at least one chiral agent A and at least one chiral agent whose helical inductive force does not change when irradiated with light (hereinafter simply referred to as “chiral agent B”) may be used.
The chiral agent B may be liquid crystalline or non-liquid crystalline. Chiral agent B generally contains an asymmetric carbon atom in many cases. The chiral agent B may be an axially asymmetric compound or planar asymmetric compound containing no asymmetric carbon atoms.
Chiral agent B may have a polymerizable group. Examples of the polymerizable group include polymerizable groups that the chiral agent A may have.
As the chiral agent B, a known chiral agent can be used.
Chiral agent B is preferably a chiral agent that induces a helix in the opposite direction to that of chiral agent A described above. That is, for example, when the helix induced by the chiral agent A is rightward, the helix induced by the chiral agent B is leftward.

The molar absorption coefficients of chiral agent A and chiral agent B are not particularly limited, but the molar absorption coefficient at the wavelength of light irradiated in step 3 (for example, 365 nm) is 100 to 100,000 L/(mol cm). Preferably, 500 to 50,000 L/(mol·cm) is more preferable.

Each content of the chiral agent A and the chiral agent B in the composition layer can be appropriately set according to the properties (for example, retardation and wavelength dispersion) of the optically anisotropic layer to be formed. Since the twist angle of the liquid crystal compound in the optically anisotropic layer greatly depends on the types and concentrations of the chiral agents A and B added, it is possible to control the alignment state of the liquid crystal compound by adjusting these. can.

The total content of the chiral agent (total content of all chiral agents) in the composition layer is not particularly limited, but from the viewpoint of facilitating control of the alignment state of the liquid crystal compound, 5.5. 0% by mass or less is preferable, 4.0% by mass or less is more preferable, and 2.0% by mass or less is even more preferable. Although the lower limit is not particularly limited, it is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.05% by mass or more.

Although the content of the chiral agent A in the chiral agent is not particularly limited, it is preferably 5 to 95% by mass, more preferably 10 to 90% by mass, based on the total mass of the chiral agent in terms of facilitating control of the alignment state of the liquid crystal compound. is more preferred.

Moreover, the composition layer may contain a polymerization initiator. When the composition layer contains a polymerization initiator, polymerization of the liquid crystal compound having a polymerizable group proceeds more efficiently.
Polymerization initiators include known polymerization initiators, including photopolymerization initiators and thermal polymerization initiators, with photopolymerization initiators being preferred. In particular, a polymerization initiator that is sensitive to light irradiated in step 5 described later is preferred.

The polymerization initiator has a maximum molar extinction coefficient among the wavelengths of light irradiated in step 3, which is 0.1 times or less with respect to the maximum molar extinction coefficient among the wavelengths of light irradiated in step 5. is preferably
Further, the molar absorption coefficient of the polymerization initiator at the wavelength of light irradiation in step 3 is preferably 5000 L/(mol cm) or less, more preferably 4000 L/(mol cm) or less, and 3000 L/(mol cm) or less. is more preferred. The lower limit is not particularly limited, and is preferably 0 L/(mol·cm), but is often 30 L/(mol·cm) or more.
Although the content of the polymerization initiator in the composition layer is not particularly limited, it is preferably 0.01 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total mass of the composition layer.

The composition layer may contain a photosensitizer.
The type of photosensitizer is not particularly limited, and includes known photosensitizers.
The molar absorption coefficient of the photosensitizer at the wavelength of light irradiation in step 3 is preferably 5000 L/(mol cm) or less, more preferably 4800 L/(mol cm) or less, and 4500 L/(mol cm). More preferred are: The lower limit is not particularly limited, and is preferably 0 L/(mol·cm), but is often 30 L/(mol·cm) or more.
The content of the photosensitizer in the composition layer is not particularly limited, but is preferably 0.01 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total mass of the composition layer.

The composition layer may contain a polymerizable monomer different from the liquid crystal compound having a polymerizable group. Polymerizable monomers include radically polymerizable compounds and cationically polymerizable compounds, and polyfunctional radically polymerizable monomers are preferred. Examples of polymerizable monomers include polymerizable monomers described in paragraphs 0018 to 0020 of JP-A-2002-296423.
Although the content of the polymerizable monomer in the composition layer is not particularly limited, it is preferably 1 to 50% by mass, more preferably 5 to 30% by mass, based on the total mass of the liquid crystal compound.

The composition layer may contain a surfactant. Surfactants include conventionally known compounds, and fluorine-based compounds are preferred. Specific examples include compounds described in paragraphs 0028 to 0056 of JP-A-2001-330725 and compounds described in paragraphs 0069-0126 of Japanese Patent Application No. 2003-295212.

The composition layer may contain a polymer. Polymers include cellulose esters. Cellulose esters include those described in paragraph 0178 of JP-A-2000-155216.
Although the content of the polymer in the composition layer is not particularly limited, it is preferably 0.1 to 10% by mass, more preferably 0.1 to 8% by mass, based on the total mass of the liquid crystal compound.

In addition to the above, the composition layer may contain an additive (alignment control agent) that promotes horizontal alignment or vertical alignment in order to bring the liquid crystal compound into a horizontal alignment state or a vertical alignment state.

[substrate]
As will be described later, when forming the composition layer, it is preferable to form the composition layer on the substrate.
A substrate is a plate that supports the composition layer.
A transparent substrate is preferable as the substrate. The transparent substrate means a substrate having a visible light transmittance of 60% or more, preferably 80% or more, more preferably 90% or more.

The thickness direction retardation value (Rth(550)) of the substrate at a wavelength of 550 nm is not particularly limited, but is preferably −110 to 110 nm, more preferably −80 to 80 nm.
The in-plane retardation value (Re(550)) of the substrate at a wavelength of 550 nm is not particularly limited, but is preferably 0 to 50 nm, more preferably 0 to 30 nm, and even more preferably 0 to 10 nm.

As a material for forming the substrate, a polymer having excellent optical properties such as transparency, mechanical strength, thermal stability, moisture shielding property, and isotropy is preferable.
Polymer films that can be used as substrates include, for example, cellulose acylate films (e.g., cellulose triacetate film (refractive index: 1.48), cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film), Polyolefin films such as polyethylene and polypropylene, polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films, polyacrylic films such as polymethylmethacrylate, polyurethane films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films , polyether ketone film, (meth)acrylonitrile film, and polymer film having an alicyclic structure (norbornene resin (Arton: trade name, manufactured by JSR Corporation, amorphous polyolefin (Zeonex: trade name, Nippon Zeon company))).
Among them, triacetyl cellulose, polyethylene terephthalate, or a polymer having an alicyclic structure is preferable as the material for the polymer film, and triacetyl cellulose is more preferable.

The substrate may contain various additives (eg, optically anisotropic modifier, wavelength dispersion modifier, fine particles, plasticizer, UV inhibitor, antidegradation agent, release agent, etc.).

Although the thickness of the substrate is not particularly limited, it is preferably 10 to 200 μm, more preferably 10 to 100 μm, even more preferably 20 to 90 μm. Also, the substrate may consist of a laminate of a plurality of sheets. The substrate may be subjected to a surface treatment (eg, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment) on the surface of the substrate to improve adhesion with the layer provided thereon.
Further, an adhesive layer (undercoat layer) may be provided on the substrate.
In addition, inorganic particles having an average particle size of about 10 to 100 nm are added to the substrate as a solid content in order to provide slipperiness during the transportation process and to prevent sticking between the back surface and the front surface after winding. A polymer layer mixed with 5 to 40 mass % by mass ratio may be arranged on one side of the substrate.

The substrate may be a so-called temporary support. That is, the substrate may be peeled off from the optically anisotropic layer after carrying out the manufacturing method of the present invention.

Alternatively, the surface of the substrate may be directly rubbed. That is, a substrate subjected to rubbing treatment may be used. The direction of the rubbing treatment is not particularly limited, and an optimum direction is appropriately selected according to the direction in which the liquid crystal compound is to be oriented.
For the rubbing treatment, a treatment method widely employed as a liquid crystal alignment treatment step for LCDs (liquid crystal displays) can be applied. That is, a method of obtaining orientation by rubbing the surface of the substrate in a given direction with paper, gauze, felt, rubber, nylon fiber, polyester fiber, or the like can be used.

An alignment film may be arranged on the substrate.
The alignment film is formed by rubbing an organic compound (preferably polymer), oblique vapor deposition of an inorganic compound, formation of a layer having microgrooves, or organic compound (eg, ω-tricosane) by the Langmuir-Blodgett method (LB film). acid, dioctadecylmethylammonium chloride, methyl stearate).
Furthermore, an alignment film is also known in which an alignment function is produced by application of an electric field, application of a magnetic field, or light irradiation (preferably polarized light).
The alignment film is preferably formed by rubbing a polymer.

Examples of the polymer contained in the alignment film include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly(N- methylol acrylamide), polyesters, polyimides, vinyl acetate copolymers, carboxymethyl cellulose, and polycarbonates. A silane coupling agent can also be used as the polymer.
Among them, water-soluble polymers (e.g., poly(N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol or modified polyvinyl alcohol is more preferred, and polyvinyl alcohol or modified Polyvinyl alcohol is more preferred.

As described above, the alignment film is formed by coating a substrate with a solution containing the above-mentioned polymer, which is an alignment film-forming material, and optional additives (for example, a cross-linking agent), followed by heat drying (cross-linking) and rubbing treatment. can be formed by

[Procedure of step 1]
In step 1, a composition layer containing the components described above is formed, but the procedure is not particularly limited. For example, a method of applying a composition containing a liquid crystal compound having a polymerizable group as described above on a substrate and optionally performing a drying treatment (hereinafter also simply referred to as a “coating method”), and a separate composition. A method of forming a layer and transferring it onto a substrate can be mentioned. Among them, the coating method is preferable from the viewpoint of productivity.
The coating method will be described in detail below.

The composition used in the coating method includes the liquid crystal compound having a polymerizable group as described above, and other components used as necessary (e.g., chiral agent, polymerization initiator, polymerizable monomer, surfactant , and polymers, etc.).
The content of each component in the composition is preferably adjusted to the content of each component in the composition layer described above.

The coating method is not particularly limited, and examples thereof include wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating.
In addition, after applying the composition, the composition layer applied on the substrate may be dried, if necessary. The solvent can be removed from the composition layer by performing the drying treatment.

The film thickness of the composition layer is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, even more preferably 0.5 to 10 μm.

(Step 2)
Step 2 is a step of heat-treating the composition layer to orient the liquid crystal compound in the composition layer. By carrying out this step, the liquid crystal compound in the composition layer is in a predetermined alignment state. For example, as shown in FIG. 6, a composition layer 22 in which a liquid crystal compound LC is homogeneously aligned is formed on a substrate 20 .

As the conditions for the heat treatment, optimal conditions are selected according to the liquid crystal compound used, and the conditions are preferably equal to or higher than the phase transition temperature of the liquid crystal compound from solid to liquid crystal phase.
Above all, the heating temperature is often 25 to 250°C, more often 40 to 150°C, and even more often 50 to 130°C.
The heating time is often 0.1 to 60 minutes, more often 0.2 to 5 minutes.

(Step 3)
Step 3 is a step, after step 2, of irradiating the composition layer with light under the condition of an oxygen concentration of 1% by volume or more.
As shown in FIG. 7, in step 3 described above, under the condition of an oxygen concentration of 1% by volume or more, from the direction opposite to the composition layer 22 side of the substrate 20 (the direction of the white arrow in FIG. 7) Light irradiation is performed. Although the light irradiation is performed from the substrate 20 side in FIG. 7, it may be performed from the composition layer 22 side.
At that time, comparing the lower region 22A of the composition layer 22 on the side of the substrate 20 with the upper region 22B on the side opposite to the substrate 20 side, the surface of the upper region 22B is closer to the air side. The oxygen concentration in the lower region 22A is high, and the oxygen concentration in the lower region 22A is low. Therefore, when the composition layer 22 is irradiated with light, the polymerization of the liquid crystal compound readily proceeds in the lower region 22A, and the alignment state of the liquid crystal compound is fixed.
In addition, since the oxygen concentration is high in the upper region 22B, the polymerization of the liquid crystal compound is inhibited by oxygen even if light irradiation is performed, and the polymerization hardly progresses.
In other words, by carrying out Step 3, the alignment state of the liquid crystal compound is easily fixed in the substrate-side region (lower region) of the composition layer. In addition, in the region (upper region) on the opposite side of the substrate side of the composition layer, the fixation of the alignment state of the liquid crystal compound is difficult to proceed, and the liquid crystal compound can be fixed by performing any of the requirements 1 to 4 described later. An isotropic phase can be formed.

Step 3 is carried out under conditions of an oxygen concentration of 1% by volume or more. Among them, the oxygen concentration is preferably 2% by volume or more, more preferably 5% by volume or more, from the viewpoint of easy production of the optical element of the present invention. Although the upper limit is not particularly limited, it may be 100% by volume.

The amount of light irradiation in step 3 is not particularly limited, but is preferably 300 mJ/cm ² or less, more preferably 200 mJ/cm ² or less, and less than 100 J/cm ² in terms of easy formation of a predetermined optically anisotropic layer. is more preferred. The lower limit is preferably 10 mJ/cm ² or more, more preferably 30 mJ/cm ² or more, from the viewpoint of easy formation of a predetermined optically anisotropic layer.
The light irradiation in step 3 is preferably carried out at 15 to 70°C (preferably 15 to 50°C).

The light used for light irradiation is not particularly limited as long as it is light that causes fixation of the alignment state of the liquid crystal compound in the substrate-side region (lower region) of the composition layer. For example, emission line spectra of mercury lamps, far ultraviolet rays represented by excimer lasers, extreme ultraviolet rays, X-rays, ultraviolet rays, and electron beams. Among them, ultraviolet rays are preferable.

(Step 4)
Step 4 is a step of pressing a mold having an uneven structure on its surface against the surface of the composition layer opposite to the substrate side to transfer the uneven structure of the mold to the composition layer. In this step, as shown in FIG. 8, a mold 24 having an uneven surface structure in which a plurality of projections 28 are arranged on a support 26 is prepared. The concave-convex structure of the mold is transferred to the composition layer 22 by pressing against the composition layer 22 .
In this aspect, since the requirement 1 is satisfied as described above, this step 4 is performed under heating conditions equal to or higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer. do. By carrying out the heat treatment, the alignment state of the liquid crystal compound (not shown) is not fixed in the upper region 22B of the composition layer 22, so the alignment state is disturbed and changes to an isotropic phase. On the other hand, in the lower region 22A of the composition layer 22, as described above, the alignment state of the liquid crystal compound LC is fixed by the above step 3. Therefore, even if the above heat treatment is performed, the alignment of the liquid crystal compound LC is fixed. The state does not change.

As for the mold used in this step, a mold having an optimum shape is appropriately adopted according to the shape of the convex portion of the optically isotropic member to be formed.

The heating conditions for performing the above-described requirement 1 (step 4 is performed under heating conditions equal to or higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer) include: It may be higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the substance layer, and is preferably 5° C. or more higher than the phase transition temperature. Although the upper limit is not particularly limited, it is preferably 100° C. higher than the phase transition temperature or lower.

After transferring the concave-convex structure of the mold to the composition layer, the mold may be peeled off as appropriate. Alternatively, the mold may be separated after performing step 5, which will be described later.

(Step 5)
In step 5, the composition layer is cured to form an optically anisotropic layer and an optically isotropic member having projections projecting from the substrate side to the side opposite to the optically anisotropic layer side. It is a step of forming an optical element having By carrying out this step, an optical element 10C having an optically anisotropic layer 12 and an optically isotropic member 14C having convex portions 16C as shown in FIG. 10 is formed. In the embodiment of FIG. 10, the optically anisotropic layer 12 is a layer formed by fixing a homogeneously aligned liquid crystal compound.

The curing treatment method is not particularly limited, and includes photocuring treatment and heat curing treatment.
The temperature conditions for the heat curing treatment are not particularly limited as long as the polymerization reaction of the liquid crystal compound having a polymerizable group can be carried out.
The heating time for the thermosetting treatment is not particularly limited, but is preferably 30 to 600 seconds, more preferably 60 to 300 seconds.
As the photo-curing treatment, ultraviolet irradiation treatment is preferable.
A light source such as an ultraviolet lamp is used for ultraviolet irradiation.
Although the irradiation amount of light (eg, ultraviolet rays) is not particularly limited, it is generally preferably about 100 to 1000 mJ/cm ² , more preferably more than 300 mJ/cm ² and not more than 1000 mJ/cm ² .
When the photo-curing treatment is carried out, it is preferably carried out under the condition that the oxygen concentration is less than 1% by volume (preferably, the oxygen concentration is 0.1% by volume or less). Although the lower limit of the oxygen concentration is not particularly limited, 0% by volume can be mentioned.

Although the embodiment of Requirement 1 has been described above, the present invention may satisfy any one of Requirements 2 to 4 instead of Requirement 1.
For example, in requirement 2, step 5 is performed under heating conditions equal to or higher than the phase transition temperature of the composition forming the composition layer from the liquid crystal phase to the isotropic phase. More specifically, as the curing treatment in step 5, by adopting a heat curing treatment performed under heating conditions equal to or higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer, Requirement 2 can be satisfied. When Requirement 2 is satisfied, the alignment state of the liquid crystal compound in the upper region of the composition layer is disturbed and changes to an isotropic phase, as in the case of satisfying Requirement 1 described above, and as a result, the desired optical element is formed. can.
When the requirement 2 is satisfied, the temperature of the heat curing treatment in step 5 is preferably 5° C. or more higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer. Although the upper limit is not particularly limited, it is preferably 100° C. higher than the phase transition temperature or lower.

Requirement 3 further includes, between steps 3 and 4, step 6 of heating the composition layer to a temperature equal to or higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition forming the composition layer.
Requirement 4 further includes, between steps 4 and 5, step 7 of heating the composition layer to a temperature equal to or higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition forming the composition layer.
By performing step 6 or 7 above, similarly to requirements 1 and 2, the alignment state of the liquid crystal compound in the upper region of the composition layer is disturbed and changes to an isotropic phase, and as a result, the desired optical element can be formed.
The temperature of the heat curing treatment in steps 6 and 7 is preferably 5° C. or more higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer. Although the upper limit is not particularly limited, it is preferably 100° C. higher than the phase transition temperature or lower.

In the above description, the optically anisotropic layer is a layer in which the alignment state of one liquid crystal compound is fixed. A plurality of optically anisotropic layers can also be formed.
For example, in the following, a first region in which the alignment state of the liquid crystal compound twisted along the helical axis extending along the thickness direction is fixed, and a second region in which the alignment state of the homogeneously aligned liquid crystal compound is fixed and are formed along the thickness direction of the optically anisotropic layer.

When forming the optically anisotropic layer as described above, there is a method of using a composition layer further containing the chiral agent A and the chiral agent B.
In this method, the absolute value of the weighted average helical induced force of the chiral agent in the composition layer obtained in step 1 is preferably 0.0 to 1.9 μm ⁻¹ , more preferably 0.0 to 1.5 μm ^{−1 . 1} , more preferably 0.0 to 1.0 μm ⁻¹ , particularly preferably 0.0 to 0.5 μm ⁻¹ , and 0.0 to 0.02 μm ⁻¹ 1 is more particularly preferred, and 0 is most preferred.

The weighted average helical inductive force of the chiral agent means, when two or more chiral agents are contained in the composition, the helical inductive force of each chiral agent contained in the composition layer and the composition of each chiral agent. It represents the total value obtained by dividing the product with the concentration (% by mass) in the layer by the total concentration (% by mass) of the chiral agent in the composition layer. For example, when two kinds of chiral agents (chiral agent X and chiral agent Y) are used in combination, it is represented by the following formula (Y).
Formula (Y) Weighted average helical inductive force (μm ⁻¹ )=(helical induced force of chiral agent X (μm ⁻¹ )×concentration of chiral agent X in composition layer (mass %)+helical induced force of chiral agent Y force (μm ⁻¹ )×concentration of chiral agent Y in composition layer (% by mass))/(concentration of chiral agent X in composition layer (% by mass)+concentration of chiral agent Y in composition layer ( mass%))
However, in the above formula (Y), when the helical direction of the chiral agent is right-handed, the helical induced force is a positive value. Moreover, when the helical direction of the chiral agent is left-handed, the helical induced force is taken as a negative value. That is, for example, in the case of a chiral agent having a helical inductive force of 10 μm ⁻¹ , when the helical direction of the helix induced by the chiral agent is right-handed, the helical inductive force is expressed as 10 μm ⁻¹ . On the other hand, when the helical direction of the helical induced by the chiral agent is left-handed, the helical induced force is expressed as -10 μm ^-1 .

When the absolute value of the weighted average helical induced force of the chiral agent in the composition layer formed in step 1 is 0, performing step 2 results in, on substrate 30, as shown in FIG. A composition layer 32 is formed in which the liquid crystal compound LC is homogeneously aligned. In addition, the chiral agent A and the chiral agent B are present at the same concentration in the composition layer 32 shown in FIG. Assume that the spiral direction is right-handed. Further, the absolute value of the helical inductive force of the chiral agent A and the absolute value of the helical inductive force of the chiral agent B are assumed to be the same.

Next, when Step 3 described above is performed, as shown in FIG. 32B, since the surface of the upper region 32B is closer to the air, the oxygen concentration in the upper region 32B is higher and the oxygen concentration in the lower region 32A is lower. Therefore, when the composition layer 32 is irradiated with light, the polymerization of the liquid crystal compound readily proceeds in the lower region 32A, and the alignment state of the liquid crystal compound is fixed. Note that the chiral agent A is also present in the lower region 32A, and the chiral agent A is also exposed to light, and the helical inducing force changes. However, since the alignment state of the liquid crystal compound is fixed in the lower region 32A, the alignment state of the liquid crystal compound does not change even if any one of the requirements 1 to 4 is implemented.
In addition, since the oxygen concentration is high in the upper region 32B, the polymerization of the liquid crystal compound is inhibited by oxygen even if light irradiation is performed, and the polymerization hardly progresses. Since the chiral agent A is also present in the upper region 32B, the chiral agent A is exposed to light and the helical induced force changes. Therefore, when step 8, which will be described later, is carried out, the alignment state of the liquid crystal compound changes along with the changed helical inducing force.
In other words, by carrying out Step 3, the alignment state of the liquid crystal compound is easily fixed in the substrate-side region (lower region) of the composition layer. In addition, in the region (upper region) on the opposite side of the substrate side of the composition layer, the fixation of the alignment state of the liquid crystal compound is difficult to progress, and the helical inducing force changes according to the chiral agent A exposed to light. .

Next, step 8 of heating the resulting composition layer is performed. By carrying out Step 8, in the upper region 32B of the composition layer 32, an alignment state is formed in which the liquid crystal compound LC is twisted according to the change in the spiral inducing force of the chiral agent A.
The heating temperature in step 8 is not particularly limited, and an optimum temperature is appropriately selected depending on the type of liquid crystal compound. lower temperatures are preferred. The lower limit of the heating temperature in step 8 is not particularly limited, and is preferably equal to or higher than the phase transition temperature from the solid state to the liquid crystal phase.
In the following, the reason why the alignment state changes as described above will be described in detail.

As described above, when step 3 is performed on the composition layer 32 shown in FIG. 11, the alignment state of the liquid crystal compound is fixed in the lower region 32A, whereas the liquid crystal compound is not aligned in the upper region 32B. Polymerization is difficult to progress, and the alignment state of the liquid crystal compound is not fixed. Moreover, the spiral induction force of the chiral agent A changes in the upper region 32B. When such a change in the helical induction force of the chiral agent A occurs, the force to twist the liquid crystal compound in the upper region 32B changes as compared with the state before light irradiation. This point will be explained in more detail.
As described above, the chiral agent A and the chiral agent B are present at the same concentration in the composition layer 32 shown in FIG. The induced spiral direction is right-handed. Moreover, the absolute value of the helical inductive force of the chiral agent A and the absolute value of the helical inductive force of the chiral agent B are the same. Therefore, the weighted average helical induction force of the chiral agent in the composition layer before light irradiation is zero.
The above aspect is shown in FIG. In FIG. 14 , the vertical axis represents “spiral inductive force of chiral agent (μm ⁻¹ )×concentration of chiral agent (% by mass)”, and the more the value is away from zero, the larger the helical inductive force. First, the relationship between the chiral agent A and the chiral agent B in the composition layer before light irradiation corresponds to the time when the amount of light irradiation is 0, and is expressed as "spiral inducing force of chiral agent A (μm ⁻¹ )× This corresponds to a state in which the absolute value of "concentration of chiral agent A (% by mass)" is equal to the absolute value of "spiral inducing force of chiral agent B (μm ⁻¹ )×concentration of chiral agent B (% by mass)". That is, the helical inducing forces of the chiral agent A that induces left-handedness and the chiral agent B that induces right-handedness are canceled out.
When light irradiation is performed in the upper region 32B in such a state and the helical induction force of the chiral agent A decreases depending on the amount of light irradiation as shown in FIG. The weighted average helical induced force of the agent becomes larger, and the right-handed helical induced force becomes stronger. That is, the helix inducing force for inducing the helix of the liquid crystal compound increases in the direction (+) of the helix induced by the chiral agent B as the irradiation dose increases.
Therefore, when heat treatment is applied to the composition layer 32 after the step 3 in which such a change in the weighted average helical inductive force occurs to promote reorientation of the liquid crystal compound, as shown in FIG. In the region 32B, the liquid crystal compound LC is twisted along the helical axis extending along the thickness direction of the composition layer 32 .
On the other hand, as described above, in the lower region 32A of the composition layer 32, the alignment state of the liquid crystal compound is fixed by the polymerization of the liquid crystal compound during the step 3. Therefore, the realignment of the liquid crystal compound does not occur. does not proceed.

In FIGS. 14 and 15, an embodiment using a chiral agent whose helical inducing force is reduced by light irradiation as the chiral agent A has been described, but the present invention is not limited to this embodiment. For example, as the chiral agent A, a chiral agent whose helical inductive force increases upon irradiation with light may be used. In this case, the helical induction force induced by the chiral agent A is increased by light irradiation, and the liquid crystal compound is twisted in the direction of rotation induced by the chiral agent A.
Moreover, in FIGS. 14 and 15 above, an embodiment in which the chiral agent A and the chiral agent B are used in combination has been described, but the present invention is not limited to this embodiment. For example, two chiral agents A may be used. Specifically, the chiral agent A1 that induces left-handedness and the chiral agent A2 that induces right-handedness may be used in combination. Chiral agents A1 and A2 may each independently be a chiral agent that increases the helical inducing power or may be a chiral agent that decreases the helical inducing power. For example, a chiral agent that induces left-handedness and whose helical inductive force is increased by light irradiation and a chiral agent that induces right-handedness and whose helical inductive force is reduced by light irradiation are used in combination. You may

Next, when the composition layer obtained above is subjected to step 3 again, as shown in FIG. In the region 32C, which is the region on the side, the polymerization of the liquid crystal compound easily progresses, and the alignment state of the liquid crystal compound is fixed. On the other hand, in the region 32D, which is the region on the side opposite to the substrate 30 side in the upper region, fixation of the alignment state of the liquid crystal compound is difficult to proceed.
Therefore, when the above-described steps 4 and 5 are performed on the obtained composition layer 32, and the treatment satisfying any of the requirements 1 to 4 is performed, as shown in FIG. A first region in which the alignment state of the liquid crystal compound is twisted along the helical axis extending along the thickness direction is fixed, and a second region in which the alignment state of the liquid crystal compound is homogeneously aligned is fixed. An optical element 10D having an optically anisotropic layer 12A and an optically isotropic member 14D is formed. Incidentally, as shown in FIG. 17, the optical isotropic member 14D is composed of a convex portion 16D and a base portion 18D.

<Laminate>
The optical element of the present invention may be combined with other members.
For example, the optical element of the present invention may be combined with an adhesive layer to form a laminate. In particular, the laminate of the present invention preferably has the optical element described above and an adhesive layer disposed on the optical isotropic member side of the optical element.
A known adhesive layer is used as the adhesive layer.

Also, the optical element of the present invention may be combined with a polarizer. That is, the present invention also relates to a laminate (polarizing plate) having the optical element of the present invention and a polarizer.
The polarizer may be any member that has a function of converting natural light into specific linearly polarized light, and examples thereof include absorption polarizers.
The type of polarizer is not particularly limited, and commonly used polarizers can be used. Examples thereof include iodine-based polarizers, dye-based polarizers using dichroic dyes, and polyene-based polarizers. Iodine-based polarizers and dye-based polarizers are generally produced by allowing polyvinyl alcohol to adsorb iodine or a dichroic dye and stretching the resultant.
A protective film may be arranged on one side or both sides of the polarizer.
An adhesive layer or adhesive layer may be arranged between the optical element of the present invention and the polarizer.
When the optically anisotropic layer in the optical element of the present invention is a λ/4 plate, a laminate containing the optical element of the present invention and a polarizer can be suitably used as a circularly polarizing plate.

<Application>
The optical element of the present invention can be applied to various uses. For example, the optical element of the present invention can be used for antireflection applications in display devices. More specifically, the invention also relates to a display device comprising, in that order, a polarizer, an optical element of the invention, and a display element.
Examples of the display element include known display elements such as an organic EL display element and a liquid crystal display element.
Among others, the optical element of the present invention is preferably applied to an organic EL display element. In particular, by applying the optical element of the present invention to an organic EL display element having a microcavity structure, generation of bluish tint is further suppressed.

EXAMPLES The characteristics of the present invention will be described more specifically below with reference to examples and comparative examples. Materials, usage amounts, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the gist of the present invention. Therefore, the scope of the present invention should not be construed as being restricted by the specific examples shown below.

<Example 1>
The following composition was put into a mixing tank, stirred, and heated at 90° C. for 10 minutes. Thereafter, the resulting composition was filtered through a filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm to prepare a dope. The solid content concentration of the dope was 23.5% by mass, the amount of the plasticizer added was the ratio to the cellulose acylate, and the dope solvent was methylene chloride/methanol/butanol = 81/18/1 (mass ratio). .
――――――――――――――――――――――――――――――――――
Cellulose acylate dope――――――――――――――――――――――――――――――――――
Cellulose acylate (acetyl substitution degree 2.86, viscosity average polymerization degree 310)
100 parts by mass sugar ester compound 1 (represented by chemical formula (S4)) 6.0 parts by mass sugar ester compound 2 (represented by chemical formula (S5)) 2.0 parts by mass silica particle dispersion (AEROSIL R972, Nippon Aerosil Co., Ltd.) made)
0.1 part by mass solvent (methylene chloride/methanol/butanol)
――――――――――――――――――――――――――――――――――

The dope prepared above was cast using a drum film forming machine. The dope was cast from a die in contact with a metal support cooled to 0° C., after which the resulting web (film) was stripped off. The drum was made of SUS.
After peeling the cast web (film) from the drum, it is dried for 20 minutes in a tenter device using a tenter device in which both ends of the web are clipped and conveyed at 30 to 40 ° C. during film transportation. did. Subsequently, the web was post-dried by zone heating while being rolled. The resulting web was knurled and wound up.
The resulting cellulose acylate film had a thickness of 40 μm, an in-plane retardation Re(550) of 1 nm at a wavelength of 550 nm, and a thickness direction retardation Rth(550) of 26 nm at a wavelength of 550 nm.

The produced cellulose acylate film was continuously rubbed. At this time, the longitudinal direction of the long film was parallel to the conveying direction, and the angle formed by the longitudinal direction of the film (conveying direction) and the rotation axis of the rubbing roller was 80°. When the film longitudinal direction (conveyance direction) is 90° and the clockwise direction is represented by a positive value with the film width direction as the reference (0°) when observed from the film side, the rotation axis of the rubbing roller is at 10°. . In other words, the position of the rotation axis of the rubbing roller is the position rotated counterclockwise by 80° with respect to the longitudinal direction of the film.
Using the rubbed cellulose acylate film as a substrate, a composition (1) containing a rod-like liquid crystal compound having the following composition was applied using a Giesser coater to form a composition layer.
The resulting composition layer was then heated at 80° C. for 60 seconds. This heating oriented the rod-like liquid crystal compound in the composition layer in a predetermined direction.
Thereafter, the composition layer was irradiated with ultraviolet rays using a 365 nm LED lamp (manufactured by Acroedge Co., Ltd.) at 30° C. in air containing oxygen (oxygen concentration: about 20% by volume) (irradiation amount: 15 mJ/cm ² ).
Subsequently, the obtained composition layer was heated at 80° C. for 10 seconds.
After that, the composition layer was irradiated with ultraviolet rays using a 365 nm LED lamp (manufactured by Acroedge Co., Ltd.) at 30 ° C. in air containing oxygen (oxygen concentration: about 20% by volume) (irradiation amount : 20 mJ/cm ² ).
After that, the obtained film is heated to 130 ° C. (corresponding to a temperature higher than the phase transition temperature (117 ° C.) from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer), and the uncured composition In a state where the film subjected to shaping treatment is pressed against the layer surface, nitrogen purge is performed to make the oxygen concentration 100 ppm by volume, and the composition layer is irradiated with ultraviolet rays with a metal halide lamp (manufactured by Eye Graphics Co., Ltd.). The alignment state of the liquid crystal compound was fixed (irradiation amount: 500 mJ/cm ² ).
Thereafter, the film subjected to the shaping treatment was peeled off from the composition layer to form an optically isotropic member having convex portions on the outermost surface.

The obtained optical member (F-1), as described with reference to FIG. It has an optically anisotropic layer having a second region formed by fixing the alignment state of the aligned liquid crystal compound along the thickness direction, and an optically isotropic member arranged in contact with the optically anisotropic layer. It was an optical element. As shown in FIGS. 1 and 2, the convex portions of the optically isotropic member had a truncated cone shape and were arranged in a hexagonal close-packed manner. The period PA of the plurality of protrusions (interval between adjacent protrusions) was 2.0 μm, the height HA1 of the protrusions was 1.6 μm, and the width WA1 of the upper base of the protrusions (the diameter of the upper base) was 1.0 μm, and the bottom width WA2 (bottom diameter) of the projection was 1.6 μm. The thickness of the base portion of the optically isotropic member (the thickness of the base portion 18D in FIG. 17) was 0.4 μm. The thickness of the first region of the optically anisotropic layer was 1.4 μm, and the thickness of the second region was 1.3 μm.
The optical characteristics of the optical element (F-1) were determined using AxoScan from Axometrics and analysis software (Multi-Layer Analysis) from Axometrics. The product (Δn2d2) of Δn2 and thickness d2 at a wavelength of 550 nm in the second region is 173 nm, the twist angle of the liquid crystal compound is 0°, and the orientation axis angle of the liquid crystal compound with respect to the longitudinal direction is −10 on the side in contact with the substrate. °, and −10° on the side in contact with the first region. Further, the product (Δn1d1) of Δn1 and thickness d1 at a wavelength of 550 nm in the first region is 184 nm, the twist angle of the liquid crystal compound is 75°, and the orientation axis angle of the liquid crystal compound with respect to the longitudinal direction is in the second region. It was −10° on the contact side and −85° on the air side.

――――――――――――――――――――――――――――――――――
Composition (1)
――――――――――――――――――――――――――――――――――
Rod-shaped liquid crystal compound (A) below 80 parts by mass Rod-shaped liquid crystal compound (B) below 10 parts by mass Polymerizable compound (C) below 10 parts by mass Ethylene oxide-modified trimethylolpropane triacrylate (V # 360, Osaka Organic Chemical ( Ltd.) 4 parts by mass Photopolymerization initiator (Irgacure 819, manufactured by BASF) 3 parts by mass Left-handed chiral agent (L1) 0.43 parts by mass Below right-handed chiral agent (R1) 0.38 parts by mass Below Polymer (A) 0.08 parts by mass Polymer (E) below 0.50 parts by mass Methyl isobutyl ketone 116 parts by mass Ethyl propionate 40 parts by mass ―――――――――――――――――― ―――――――――――――――――

Rod-shaped liquid crystal compound (A) (hereinafter referred to as a mixture of compounds)

Rod-shaped liquid crystal compound (B) (hereinafter, see structural formula)

Polymerizable compound (C) (hereinafter, see structural formula)

Left-handed chiral agent (L1) (see structural formula below)

Right-handed chiral agent (R1) (see structural formula below)

Polymer (A) (hereinafter, see the structural formula. In the formula, the numerical value described in each repeating unit represents the content (% by mass) of each repeating unit with respect to all repeating units.)

Polymer (E) (Hereinafter, see the structural formula. In the formula, the numerical value described in each repeating unit represents the content (% by mass) of each repeating unit with respect to all repeating units.)

<Example 2>
The cellulose acylate film prepared in Example 1 was passed through a dielectric heating roll at a temperature of 60°C to raise the surface temperature of the film to 40°C. It was applied with a coating amount of 14 ml/m ² using a bar coater, and conveyed under a steam type far-infrared heater manufactured by Noritake Co., Ltd. heated to 110° C. for 10 seconds. Subsequently, using the same bar coater, 3 ml/m ² of pure water was applied. Next, after repeating water washing with a fountain coater and draining with an air knife three times, the film was transported to a drying zone at 70° C. for 10 seconds and dried to prepare a cellulose acylate film saponified with an alkali.
――――――――――――――――――――――――――――――――――
Alkaline solution――――――――――――――――――――――――――――――――
Potassium hydroxide 4.7 parts by weight Water 15.8 parts by weight _Isopropanol 63.7 parts _by weight Surfactant: _C14H29O ( _CH2CH2O ) _20H 1.0 parts by weight Propylene glycol 14.8 parts by weight ――――――――――――――――――――――――――――――――――

An orientation film coating solution having the following composition was continuously applied to the alkali-saponified surface of the cellulose acylate film using a #14 wire bar. It was dried with hot air at 60°C for 60 seconds and then with hot air at 100°C for 120 seconds.

――――――――――――――――――――――――――――――――――
Alignment film coating solution――――――――――――――――――――――――――――――――――
Modified polyvinyl alcohol shown below 28 parts by mass Citric acid ester (AS3, manufactured by Sankyo Chemical Co., Ltd.) 1.2 parts by mass Photopolymerization initiator (Irgacure 2959, manufactured by BASF) 0.84 parts by mass Glutaraldehyde 2.8 parts by mass Water 699 parts by mass Methanol 226 parts by mass ――――――――――――――――――――――――――――――――――

Modified polyvinyl alcohol (see structural formula below)

The alignment film prepared above was continuously subjected to rubbing treatment. At this time, the longitudinal direction of the long film was parallel to the conveying direction, and the angle between the longitudinal direction of the film (conveying direction) and the rotation axis of the rubbing roller was 45°. If the longitudinal direction (conveyance direction) of the film is 90° and the clockwise direction is expressed as a positive value with the width direction of the film as the reference (0°) when observed from the film side, the rotation axis of the rubbing roller is 135°. be. In other words, the position of the rotation axis of the rubbing roller is the position rotated counterclockwise by 45° with respect to the longitudinal direction of the film.

Using the rubbing-treated cellulose acylate film with an alignment film as a substrate, a composition (2) containing a rod-like liquid crystal compound having the following composition was applied using a Giesser coater to form a composition layer.
The resulting composition layer was then heated at 120° C. for 80 seconds. This heating oriented the rod-like liquid crystal compound in the composition layer in a predetermined direction.
Thereafter, the composition layer was irradiated with ultraviolet rays for 5 seconds using a 365 nm LED lamp (manufactured by Acroedge Co., Ltd.) at 40° C. in air containing oxygen (oxygen concentration: about 20% by volume) (irradiation amount: 50 mJ/cm ² ).
Subsequently, the resulting film was treated at 195 ° C. (corresponding to a temperature higher than the phase transition temperature (190 ° C.) from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer). While pressing the film subjected to shaping treatment to the surface of the composition layer, nitrogen purge is performed to set the oxygen concentration to 100 ppm by volume, and ultraviolet rays are applied to the composition layer using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.). The alignment state of the liquid crystal compound was fixed by irradiating the liquid crystal compound (irradiation dose: 500 mJ/cm ² ). After that, the film subjected to the shaping treatment was peeled off from the composition layer to form an optically isotropic member having convex portions on the outermost surface.
The obtained optical member (F-2), as described with reference to FIGS. and an optical isotropic member arranged in contact with the optical element. The shape and arrangement of the convex portions of the optically isotropic member were the same as in Example 1. The thickness of the base portion of the optically isotropic member (the thickness of the base portion 18A in FIG. 1) was 0.4 μm. The thickness of the optically anisotropic layer was 3.0 μm.
The optical properties of the optical element (F-2) were determined using AxoScan from Axometrics and analysis software (Multi-Layer Analysis) from Axometrics. The in-plane retardation of the optically anisotropic layer at a wavelength of 550 nm was 140 nm, and the angle of the in-plane slow axis with respect to the longitudinal direction of the film was -45°.

―――――――――――――――――――――――――――――――――――――
Composition (2)
―――――――――――――――――――――――――――――――――――――
The above rod-shaped liquid crystal compound (A) 20 parts by mass The following rod-shaped liquid crystal compound (D) 40 parts by mass The following rod-shaped liquid crystal compound (E) 40 parts by mass Ethylene oxide-modified trimethylolpropane triacrylate (V # 360, Osaka Organic Chemical ( Co., Ltd.) 4 parts by mass Photopolymerization initiator (Irgacure 819, manufactured by BASF) 3 parts by mass Polymer (A) above 0.08 parts by mass Methyl ethyl ketone 156 parts by mass ―――――――――――――― ―――――――――――――――――――――――

Rod-shaped liquid crystal compound (D) (see structural formula below)

Rod-shaped liquid crystal compound (E) (see structural formula below)

<Example 3>
As shown in FIGS. 4 and 5, the optical element (F- 3) was obtained.
The obtained optical member (F-3), as described with reference to FIGS. and an optical isotropic member arranged in contact with the optical element. As shown in FIGS. 4 and 5, the convex portions of the optically isotropic member had a trapezoidal cross section and were arranged in stripes. The period PB (interval between adjacent protrusions) of the plurality of protrusions was 2.0 μm, the height HB1 of the protrusions was 1.6 μm, and the width WB1 of the upper base of the protrusions was 1.0 μm. , and the width WA2 of the bottom of the convex portion was 1.6 μm. The thickness of the base portion of the optically isotropic member was 0.4 μm. The thickness of the optically anisotropic layer was 3.0 μm.
The optical properties of the optical element (F-3) were determined using AxoScan from Axometrics and analysis software (Multi-Layer Analysis) from Axometrics. The in-plane retardation of the optically anisotropic layer at a wavelength of 550 nm was 140 nm, and the angle of the in-plane slow axis with respect to the longitudinal direction of the film was -45°.

<Example 4>
An optical element (F-4) was obtained according to the same procedure as in Example 2, except that the film subjected to the shaping treatment was changed so that a moth-eye structure in which convex portions were randomly arranged was obtained.
The resulting optical member (F-4) comprises an optically anisotropic layer which is a layer formed by fixing the alignment state of a homogeneously aligned liquid crystal compound, and an optically isotropic layer disposed in contact with the optically anisotropic layer. It was an optical element having a member. The optically isotropic member had convex portions protruding on the side opposite to the optically anisotropic layer side, and the convex portions were randomly arranged. The convex portion of the optically isotropic member had a truncated cone shape that gradually increased from the optically anisotropic layer side toward the side opposite to the optically anisotropic layer side of the convex portion. The height HA1 of the protrusion is 0.4 μm, the width WA1 of the upper base of the protrusion (diameter of the upper base) is 0.18 μm, and the width WA2 of the lower base of the protrusion (diameter of the lower base) is 0. 0.05 μm. The thickness of the base portion of the optically isotropic member was 1.6 μm. The average distance between the convex portions was 0.18 μm, and the thickness of the optically anisotropic layer was 3.0 μm.
The optical properties of the optical element (F-3) were determined using AxoScan from Axometrics and analysis software (Multi-Layer Analysis) from the same company. The in-plane retardation of the optically anisotropic layer at a wavelength of 550 nm was 140 nm, and the angle of the in-plane slow axis with respect to the longitudinal direction of the film was -45°.

<Example 5>
Using the rubbing-treated cellulose acylate film with an alignment film prepared in Example 2 as a substrate, the composition (2) containing a rod-like liquid crystal compound was applied using a Giesser coater to form a composition layer.
The resulting composition layer was then heated at 120° C. for 80 seconds. This heating oriented the rod-like liquid crystal compound in the composition layer in a predetermined direction.
Thereafter, nitrogen purge is performed to set the oxygen concentration to 100 ppm by volume, and the composition layer is irradiated with ultraviolet rays (irradiation amount: 50 mJ/cm ² ) using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) to obtain a liquid crystal. An optically anisotropic layer was obtained by fixing the alignment state of the compound.
After that, the uneven structure-forming composition (1) containing zirconia nanoparticles was applied onto the optically anisotropic layer to form a composition layer. Next, with the film subjected to shaping treatment pressed against the surface of the uncured composition layer, nitrogen purge is performed to set the oxygen concentration to 100 ppm by volume, and a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) is used. Then, the composition layer was irradiated with ultraviolet rays to cure the composition containing zirconia nanoparticles, thereby obtaining an optical member (F-5).

―――――――――――――――――――――――――――――――――――――
Concavo-convex structure-forming composition (1)
―――――――――――――――――――――――――――――――――――――
Mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.) 90.0 parts by mass Zirconia nanoparticle dispersion 10.0 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by BASF) 1.3 parts by mass Photosensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.4 parts by mass RS-90 (leveling agent, manufactured by DIC Corporation) 0.1 parts by mass Methyl isobutyl ketone 120 parts by mass ―――――――――――――――――――――――――――――――――――――

The obtained optical member (F-5) comprises an optically anisotropic layer which is a layer formed by fixing the alignment state of a homogeneously aligned liquid crystal compound, and an optically isotropic layer disposed in contact with the optically anisotropic layer. It was an optical element having a member. The shape and arrangement of the convex portions of the optically isotropic member were the same as in Example 1. The thickness of the base portion of the optically isotropic member (the thickness of the base portion 18A in FIG. 1) was 0.4 μm. The thickness of the optically anisotropic layer was 3.0 μm.
The optical properties of the optical element (F-5) were determined using AxoScan from Axometrics and analysis software (Multi-Layer Analysis) from Axometrics. The in-plane retardation of the optically anisotropic layer at a wavelength of 550 nm was 140 nm, and the angle of the in-plane slow axis with respect to the longitudinal direction of the film was -45°.

<Comparative Example 1>
An optical member (F-6) was produced in the same manner as in Example 5, except that the uneven structure-forming composition (1) was changed to the uneven structure-forming composition (2).

―――――――――――――――――――――――――――――――――――――
Concavo-convex structure-forming composition (2)
―――――――――――――――――――――――――――――――――――――
Aromatic urethane acrylate (EBECRYL 220, manufactured by Daicel Allnex Co., Ltd.) 100 parts by mass Photopolymerization initiator (Irgacure 819, manufactured by BASF) 2 parts by mass Polymer (A) 0.08 parts by mass Methyl isobutyl ketone 120 parts by mass

The obtained optical member (F-6) comprises an optically anisotropic layer which is a layer formed by fixing the alignment state of a homogeneously aligned liquid crystal compound, and an optically isotropic layer disposed in contact with the optically anisotropic layer. It was an optical element having a member. The shape and arrangement of the convex portions of the optically isotropic member were the same as in Example 1. The thickness of the base portion of the optically isotropic member (the thickness of the base portion 18A in FIG. 1) was 0.4 μm. The thickness of the optically anisotropic layer was 3.0 μm.
The optical characteristics of the optical element (F-6) were determined using AxoScan from Axometrics and analysis software (Multi-Layer Analysis) from Axometrics. The in-plane retardation of the optically anisotropic layer at a wavelength of 550 nm was 140 nm, and the angle of the in-plane slow axis with respect to the longitudinal direction of the film was -45°.

<Comparative Example 2>
According to the same procedure as in Example 2, the rubbing-treated cellulose acylate film with an alignment film was used as a substrate, and the composition (2) was applied using a Gieser coater to form a composition layer.
The resulting composition layer was then heated at 120° C. for 80 seconds. This heating oriented the rod-like liquid crystal compound in the composition layer in a predetermined direction.
Then, nitrogen purge is performed to set the oxygen concentration to 100 volume ppm, and the composition layer is irradiated with ultraviolet rays using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) to fix the alignment state of the liquid crystal compound (irradiation Amount: 500 mJ/cm ² ), an optical film containing a λ/4 plate was prepared.
The optical properties of the optical film including the λ/4 plate were obtained using AxoScan from Axometrics and analysis software (Multi-Layer Analysis) from Axometrics. The in-plane retardation of the optically anisotropic layer at a wavelength of 550 nm was 140 nm, and the angle of the in-plane slow axis with respect to the longitudinal direction of the film was -45°.

Next, the cellulose acylate film (substrate) prepared in Example 1 is coated with the uneven structure-forming composition (1) used in Example 5 using a Giesser coater to form a composition layer. did. Next, with the film subjected to shaping treatment pressed against the surface of the uncured composition layer, nitrogen purge is performed to set the oxygen concentration to 100 ppm by volume, and a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) is used. Then, the composition layer was irradiated with ultraviolet rays to cure the aromatic urethane acrylate (irradiation amount: 500 mJ/cm ² ). After that, by peeling the film subjected to the shaping treatment from the composition layer, two uneven structure films (S) having protrusions on the outermost surface were produced. The shape of the unevenness was the same stripe shape as in Example 3.

<Production of polarizer>
A polyvinyl alcohol (PVA) film having a thickness of 80 μm was dyed by immersing it in an iodine aqueous solution having an iodine concentration of 0.05% by mass at 30° C. for 60 seconds. Next, the obtained film was longitudinally stretched to 5 times its original length while being immersed in an aqueous boric acid solution having a boric acid concentration of 4% by mass for 60 seconds, and dried at 50° C. for 4 minutes. , a polarizer having a thickness of 20 μm was obtained.

<Production of polarizer protective film>
A commercially available cellulose acylate film, FUJITAC TG40UL (manufactured by Fuji Film Co., Ltd.), was prepared and immersed in an aqueous sodium hydroxide solution of 1.5 mol/liter at 55° C., and then sufficient sodium hydroxide was added with water. washed away. Thereafter, the obtained film was immersed in a dilute sulfuric acid aqueous solution of 0.005 mol/liter at 35° C. for 1 minute and then immersed in water to thoroughly wash off the dilute sulfuric acid aqueous solution. Finally, the resulting film was sufficiently dried at 120° C. to produce a polarizer protective film having a saponified surface.

<Production of circularly polarizing plate>
The optical elements (F-1) to (F-6) produced above are saponified in the same manner as in the production of the polarizer protective film described above, and the polarizer and The polarizer protective films were continuously laminated using a polyvinyl alcohol-based adhesive to prepare elongated circularly polarizing plates (P-1) to (P-6). That is, circularly polarizing plates (P-1) to (P-6) had a polarizer protective film, a polarizer, a substrate, an optically anisotropic layer, and an optically isotropic member in this order.
On the substrate surface of the optical film produced in Comparative Example 2, the polarizer described above and the polarizer protective film described above were continuously bonded using a polyvinyl alcohol-based adhesive. Furthermore, the λ / 4 plate side of the obtained laminate and the uneven structure side of the uneven structure film (S) prepared in Comparative Example 2 were optically transparent adhesive (OCA tape #8146 manufactured by 3M). pasted together. Furthermore, the substrate side of the uneven structure film (S) of the obtained laminate and the uneven structure side of another uneven structure film (S) were coated with an optically transparent adhesive (OCA tape #8146 manufactured by 3M). A circularly polarizing plate (P-7) was produced by bonding using The two uneven structure films were attached so that the directions in which the protrusions extend were orthogonal to each other. In this circularly polarizing plate (P-7), an optically anisotropic layer and an optically isotropic member having convex portions were laminated via an adhesive. This circularly polarizing plate (P-7) corresponds to the aspect of Patent Document 1.

<Production of organic EL display device and evaluation of display performance>
(Mounting on display device)
GALAXY S4 manufactured by SAMSUNG equipped with an organic EL panel is disassembled, the circular polarizing plate is peeled off, and the circular polarizing plates (P-1) to (P-7) prepared in the above examples are used to protect the polarizer. It was attached to the display device with an adhesive so that the film was arranged on the outside.
(Evaluation of display performance)
(front/black display)
A black display was performed on the produced organic EL display device, and the display was observed from the front direction under environments with different brightnesses. Table 1 shows the results.
Reflected light is not visible even in an environment of 1:1000 lux.
2: Reflected light is visible under an environment of 1000 lux, but reflected light is not visible under an environment of 100 lux.
3: Reflected light is visible under an environment of 100 lux, but reflected light is not visible under an environment of 10 lux.
Reflected light is visible even in an environment of 4:10 lux.

(diagonal/white display)
The produced organic EL display device was set to display white, and the color of the display device was observed from an omnidirectional table at a polar angle of 45°, and the azimuth angle dependence of color change was evaluated according to the following criteria. Table 1 shows the results.
1: The image is visually recognized as white in all directions.
2: The image is observed to be bluish only in a specific direction.
3: The image is observed bluish in all directions.

The optically isotropic members produced in Examples 1 to 5 were confirmed to be optically isotropic in the method of measuring the retardation of the section sample by the Senarmont method described above.
Also, the average refractive index of the optically anisotropic layer and the refractive index of the optically isotropic member were measured by the methods described above.

In Table 1, the "liquid crystal type" column represents the type of liquid crystal compound used to produce the optically anisotropic layer and the optically isotropic member, and the "forward wavelength dispersion" is a liquid crystal compound exhibiting forward wavelength dispersion. and "reverse wavelength dispersion" means a liquid crystal compound exhibiting reverse wavelength dispersion.
In Table 1, the "optically anisotropic layer" column represents the alignment state of the liquid crystal compound fixed in the optically anisotropic layer, and the "homogeneous alignment/twisted alignment" column represents the liquid crystal in which the optically anisotropic layer is homogeneously aligned. The term "homogeneous alignment" means that the optically anisotropic layer is a layer in which a homogeneously oriented liquid crystal compound is fixed. It means that there is
In Table 1, the "convex portion" column represents the shape of the convex portion of the optically isotropic member.
In Table 1, the "refractive index difference" column represents the absolute value of the difference between the average refractive index of the optically anisotropic layer and the refractive index of the optically isotropic member.
In Table 1, the "contact" column indicates "A" when the optically anisotropic layer and the optically isotropic member are in contact with each other in each example and comparative example, and "B" when they are not in contact with each other.

As shown in Table 1 above, it was confirmed that the optical element of the present invention exhibited the desired effects.
In the display devices of Examples 1 and 2, in the oblique/white display, the image was visually recognized as white in all directions, and the display performance was good. As for the display performance of Example 3, in the oblique/white display, the image was visually recognized as white when observed from the direction orthogonal to the direction in which the protrusions extend, but when viewed in a direction parallel to the direction in which the protrusions extend. The image was observed to be bluish when observed from a different direction. In addition, in order to make the image of the display device of Example 3 visible white in all directions, an optical element having an optically isotropic member having stripe-shaped convex portions was separately prepared, and the optical element in this optical element The direction in which the convex portions of the isotropic member extend is orthogonal to the direction in which the convex portions of the optical isotropic member in the optical element included in the display device of Example 3 extend. In addition, there is a method in which a separately prepared optical element is further laminated on the display device of the third embodiment. In the display device of Example 4, reflection at the interface between the optically anisotropic layer and the pressure-sensitive adhesive was suppressed by the convex portion (structural portion), so reflected light was not visually recognized in front/black display, and display performance was excellent. there were.

10A, 10B, 10C, 10D optical element 12, 12A optically anisotropic layer 14A, 14B, 14C, 14D optically isotropic member 16A, 16B, 16C, 16D convex portion 18A, 18B, 18C, 18D base portion 20, 30 Substrate 22, 32 Composition layer 24 Mold 26 Support 28 Convex portion 32A Lower region 32B Upper region 32C, 32D Region

Claims (11)

an optically anisotropic layer;
an optically isotropic member;
the optically anisotropic layer and the optically isotropic member are in contact,
the absolute value of the difference between the average refractive index of the optically anisotropic layer and the refractive index of the optically isotropic member is within 0.08;
An optical element, wherein the optically isotropic member has a convex portion protruding to the side opposite to the optically anisotropic layer. 2. The optical element according to claim 1, wherein both the optically anisotropic layer and the optically isotropic member are formed using a liquid crystal compound. 3. The optical element according to claim 1, wherein the optically anisotropic layer and the optically isotropic member are both formed using the same liquid crystal compound. The optical element according to any one of claims 1 to 3, wherein the optically anisotropic layer is a λ/4 plate. The optical element according to any one of claims 1 to 4, wherein a plurality of said convex portions are arranged periodically. The optical element according to any one of claims 1 to 5, wherein the distance between the plurality of convex portions is 0.2 to 20 µm. The optical element according to any one of claims 1 to 6, wherein the convex portions are arranged in dots or stripes. 8. The method according to any one of claims 1 to 7, wherein the width of the convex portion gradually increases from the side opposite to the optically anisotropic layer side of the convex portion toward the optically anisotropic layer side. Optical element as described. A laminate comprising the optical element according to any one of claims 1 to 8 and an adhesive layer disposed on the optical isotropic member side of the optical element. Having a polarizer, the optical element according to any one of claims 1 to 8, and a display element in this order,
A display device, wherein the optically anisotropic layer in the optical element is disposed on the polarizer side. Step 1 of forming a composition layer containing a liquid crystal compound having a polymerizable group on a substrate;
a step 2 of subjecting the composition layer to heat treatment to orient the liquid crystal compound in the composition layer;
After the step 2, a step 3 of irradiating the composition layer with light under an oxygen concentration of 1% by volume or more;
A step 4 of pressing a mold having an uneven structure on its surface against the surface of the composition layer opposite to the substrate side to transfer the uneven structure of the mold to the composition layer;
The composition layer is subjected to a curing treatment, and has an optically anisotropic layer and an optically isotropic member having convex portions projecting from the substrate side to the side opposite to the optically anisotropic layer side. and a step 5 of forming an optical element,
A method for manufacturing an optical element that satisfies any one of the following requirements 1 to 4.
Requirement 1: The step 4 is carried out under heating conditions equal to or higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer.
Requirement 2: The step 5 is carried out under heating conditions equal to or higher than the phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer.
Requirement 3: Between the steps 3 and 4, there is further a step 6 of heating the composition layer to a phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer or higher. .
Requirement 4: Between said step 4 and said step 5, it further has a step 7 of heating the composition layer to a phase transition temperature from the liquid crystal phase to the isotropic phase of the composition constituting the composition layer or higher. .

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