Polarizing plate and display device

Abstract

The present invention addresses the problem of providing: a polarizing plate which is applied to a display element to obtain a display device, which is not susceptible to causing in-plane color unevenness when viewing black display on the display device from an oblique direction, and which suppresses azimuth angle dependency of hue; and a display device related to the polarizing plate. This polarizing plate comprises a polarizer and an optical film. The optical film has an in-plane retardation of 130-150 nm at a wavelength of 550 nm, and the optical film includes, from the polarizer side, a first optically anisotropic layer, an adhesive layer, and a second optically anisotropic layer. The first optically anisotropic layer has an in-plane retardation of 150-240 nm at a wavelength of 550 nm, and a value obtained by dividing the in-plane retardation of the first optically anisotropic layer at a wavelength of 550 nm by the thickness of the first optically anisotropic layer is 0.07 to 0.116.

Description

Polarizing plate, display device

[0001] The present invention relates to a polarizing plate and a display device.

[0002] BACKGROUND ART Optically anisotropic layers having refractive index anisotropy are used in a variety of applications, such as antireflection films for various display devices such as organic electroluminescence (EL) display devices, and optical compensation films for liquid crystal display devices.

[0003] For example, Patent Document 1 discloses an optical film in which three optically anisotropic layers exhibiting predetermined optical properties are laminated.

[0004] International Publication No. 2022 / 045188

[0005] Recently, there has been a demand for further reduction in in-plane color unevenness and color change depending on the viewing direction (azimuth angle) when a display is displayed in black and viewed from an oblique direction. The present inventors have studied display devices using the optical film described in the above document and found that there are cases where the display devices cannot meet the standards currently required. Note that the in-plane color unevenness refers to the presence of regions with different colors within the display.

[0006] In view of the above circumstances, an object of the present invention is to provide a polarizing plate that is applied to a display element to obtain a display device, and that is less likely to cause in-plane color unevenness and has reduced azimuthal angle dependency of color when the display device is viewed obliquely in black display mode.

[0007] As a result of extensive research into solving the above problems, the present inventors have found that the problems can be solved by the following configuration.

[0008] [1] A polarizing plate comprising a polarizer and an optical film, wherein the optical film has an in-plane retardation of 130 to 150 nm at a wavelength of 550 nm, the optical film comprising, from the polarizer side, a first optically anisotropic layer, an adhesive layer, and a second optically anisotropic layer, wherein the first optically anisotropic layer has an in-plane retardation of 150 to 240 nm at a wavelength of 550 nm, and a value obtained by dividing the in-plane retardation of the first optically anisotropic layer at a wavelength of 550 nm by the thickness of the first optically anisotropic layer is 0.07 to 0.116. [2] The polarizing plate according to [1], wherein the adhesive layer has a thickness variation of 5 to 35 nm. [3] The polarizing plate according to [1] or [2], wherein the first optically anisotropic layer has an in-plane retardation of 150 to 180 nm at a wavelength of 550 nm. [4] The polarizing plate according to any one of [1] to [3], wherein the first optically anisotropic layer is a layer formed using a composition containing a discotic liquid crystal compound. [5] The polarizing plate according to any one of [1] to [4], wherein the thickness of the adhesion layer is 0.5 to 20 μm. [6] The polarizing plate according to any one of [1] to [5], wherein the adhesion layer is an adhesive layer or a pressure-sensitive adhesive layer. [7] The polarizing plate according to any one of [1] to [6], wherein the in-plane retardation of the optical film at a wavelength of 550 nm is 135 to 145 nm. [8] A display device comprising a display element and the polarizing plate according to any one of [1] to [7].

[0009] According to the present invention, a polarizing plate can be provided which is applied to a display element to obtain a display device, and which is less likely to produce in-plane color unevenness and has reduced azimuthal angle dependency of color when the display device is viewed obliquely in black display mode.

[0010] Fig. 1 is an example of a schematic cross-sectional view of one embodiment of the polarizing plate of the present invention. Fig. 2 is a diagram showing the relationship between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer in one embodiment of the polarizing plate of the present invention shown in Fig. 1. Fig. 3 is a schematic diagram showing the relationship between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer when observed from the direction of the white arrow in Fig. 1. Fig. 4 is an example of a schematic cross-sectional view of one embodiment of the polarizing plate of the present invention. Fig. 5 is a diagram showing the relationship between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer in one embodiment of the polarizing plate of the present invention shown in Fig. 4. Fig. 6 is a schematic diagram showing the relationship between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer when observed from the direction of the white arrow in Fig. 4.

[0011] The present invention will be described in detail below. The following description of the components may be based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0012] In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the lower and upper limits. Furthermore, in this specification, when two or more types of a certain component are present, the "content" of that component means the total content of those two or more components. In this specification, in a numerical range described in stages, the upper or lower limit value described in a certain numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in a numerical range described in this specification, the upper or lower limit value described in a certain numerical range may be replaced with a value shown in the Examples. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment.

[0013] In this specification, the slow axis is defined at 550 nm unless otherwise specified.

[0014] In this specification, Re(λ) and Rth(λ) represent the in-plane retardation and the thickness direction retardation, respectively, at a wavelength λ. Unless otherwise specified, the wavelength λ is 550 nm. In the present invention, Re(λ) and Rth(λ) are values ​​measured at a wavelength λ using an AxoScan (manufactured by Axometrics). By inputting the average refractive index ((nx + ny + nz) / 3) and film thickness (d (μm)) into AxoScan, the following slow axis direction (°) is calculated: Re(λ) = R0(λ) Rth(λ) = ((nx + ny) / 2 - nz) × d. Note that R0(λ) is displayed as a numerical value calculated by AxoScan, but it means Re(λ).

[0015] In this specification, the refractive indices nx, ny, and nz are measured using an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) with a sodium lamp (λ=589 nm) as a light source. When measuring wavelength dependency, measurements can be made using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in combination with an interference filter. Values ​​from the Polymer Handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can also be used. Examples of average refractive index values ​​for major optical films are listed below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).

[0016] As used herein, "light" refers to actinic rays or radiation, including, for example, the bright line spectrum of a mercury lamp, far ultraviolet light typified by excimer lasers, extreme ultraviolet light (EUV light: Extreme Ultraviolet), X-rays, ultraviolet light, and electron beams (EB). As used herein, "visible light" refers to light having a wavelength of 380 to 780 nm. Unless otherwise specified, the measurement wavelength is 550 nm.

[0017] In this specification, the angular relationship (e.g., "perpendicular," "parallel," etc.) is intended to include the range of error acceptable in the technical field to which the present invention pertains. Specifically, this means that the angle is within a range of less than ±10° from the exact angle, and the error from the exact angle is preferably within a range of ±5° or less, and more preferably within a range of ±3° or less.

[0018] In this specification, horizontal alignment of rod-shaped liquid crystal compounds refers to a state in which the long axes of the liquid crystal compounds are aligned parallel to the layer surface and in the same direction. Here, horizontal does not require strict horizontal alignment, but refers to an alignment in which the tilt angle between the average molecular axis of the liquid crystal compounds in the layer and the layer surface is less than 20°. Furthermore, the same direction does not require strict uniform alignment, but refers to a state in which, when the slow axis orientations are measured at any 20 positions in the plane, the maximum difference between the slow axis orientations at the 20 positions (the difference between the two slow axis orientations with the largest difference among the 20 slow axis orientations) is less than 10°. Vertical alignment of rod-shaped liquid crystal compounds refers to a state in which the long axes of the rod-shaped liquid crystal compounds are aligned perpendicular to the layer surface and in the same direction. Vertical does not require strict vertical alignment, but refers to an alignment in which the tilt angle between the average molecular axis in the layer and the layer surface is 70 to 110°. The same direction is as described above. Vertical alignment of a discotic liquid crystal compound refers to a state in which the disc planes of the liquid crystal compound are aligned perpendicular to the layer surface and in the same direction. Horizontal alignment of a discotic liquid crystal compound refers to a state in which the disc planes of the liquid crystal compound are aligned horizontally to the layer surface and in the same direction. Here, "vertical" does not require strict vertical alignment, but refers to an alignment in which the inclination angle between the disc planes of the liquid crystal compound in the layer and the layer surface is 70 to 110°. "Horizontal" does not require strict horizontal alignment, but refers to an alignment in which the inclination angle between the disc planes of the liquid crystal compound in the layer and the layer surface is 0±20°. "In the same direction" does not require strict uniform alignment, but refers to a state in which, when the slow axis orientations are measured at 20 arbitrary positions in the plane, the maximum difference between the slow axis orientations at the 20 positions (the difference between the two slow axis orientations with the largest difference) is less than 10°.

[0019] In this specification, a C plate satisfies either of the following formulas (C1) and (C2), where nx is the refractive index in the in-plane slow axis direction, ny is the refractive index in the in-plane direction perpendicular to the in-plane slow axis, and nz is the refractive index in the thickness direction. A plate that satisfies formula (C1) is a so-called positive C plate, and a plate that satisfies formula (C2) is a so-called negative C plate. A positive C plate exhibits a negative Rth, while a negative C plate exhibits a positive Rth. Formula (C1) nz>nx≒ny Formula (C2) nz<nx≒ny Note that the above "≒" encompasses not only the case where both are completely identical, but also the case where both are substantially identical. "Substantially the same" means, for example, that "nx≒ny" also encompasses the case where (nx-ny)×d (where d is the film thickness) is 0 to 10 nm, preferably 0 to 5 nm.

[0020] The polarizing plate of the present invention is a polarizing plate including a polarizer and an optical film, wherein the optical film has an in-plane retardation of 130 to 150 nm at a wavelength of 550 nm, the optical film includes, from the polarizer side, a first optically anisotropic layer, an adhesive layer, and a second optically anisotropic layer, wherein the first optically anisotropic layer has an in-plane retardation of 150 to 240 nm at a wavelength of 550 nm, and the value obtained by dividing the in-plane retardation of the first optically anisotropic layer at a wavelength of 550 nm by the thickness of the first optically anisotropic layer is 0.07 to 0.116.

[0021] Although the reason why a polarizing plate having the above configuration can solve the problems of the present invention is not entirely clear, the inventors speculate as follows. Note that the following speculation does not limit the mechanism by which the effect is obtained. In other words, even if the effect is obtained by a mechanism other than the one described below, it is still within the scope of the present invention. A laminate including a polarizer and an optical film having an in-plane retardation of 130 to 150 nm at a wavelength of 550 nm functions as a polarizing plate. Regarding the optical film including a first optically anisotropic layer, an adhesion layer, and a second optically anisotropic layer in this order, in which the first optically anisotropic layer has an in-plane retardation of 150 to 240 nm at a wavelength of 550 nm, it has surprisingly been found that by adjusting the value obtained by dividing the in-plane retardation at a wavelength of 550 nm by the thickness of the first optically anisotropic layer (i.e., refractive index anisotropy Δn) within a predetermined range, it is possible to apply the optical film to a display element to obtain a display device, and to suppress in-plane color unevenness and azimuthal angle dependence of the color when the display device is viewed obliquely in black display mode. Hereinafter, when a display device is obtained by applying the present invention to a display element and the display device is set to black display and viewed from an oblique direction, the fact that in-plane color unevenness is less likely to occur and the azimuth angle dependency of color can be suppressed will be simply referred to as "in-plane color unevenness can be suppressed" and "azimuth angle dependency of color can be suppressed," respectively, and the fact that at least one of in-plane color unevenness can be further suppressed and the azimuth angle dependency of color can be further suppressed will be referred to as "the effect of the present invention is better."

[0022] Hereinafter, each of the components that the polarizing plate of the present invention may contain will be described in detail.

[0023] [Optical Film] The polarizing plate of the present invention includes an optical film, which includes, from the polarizer side, a first optically anisotropic layer, an adhesive layer, and a second optically anisotropic layer in this order.

[0024] The optical film has an in-plane retardation of 130 to 150 nm at a wavelength of 550 nm. In terms of achieving a more excellent effect of the present invention, the in-plane retardation of the optical film at a wavelength of 550 nm is preferably 135 nm or more. In terms of achieving a more excellent effect of the present invention, the in-plane retardation of the optical film at a wavelength of 550 nm is preferably 145 nm or less.

[0025] <First Optically Anisotropic Layer> The first optically anisotropic layer is preferably a layer formed using a composition containing a liquid crystal compound, and more preferably a layer formed by fixing an aligned liquid crystal compound. Hereinafter, in this specification, the state in which the liquid crystal compound is "fixed" refers to a state in which the alignment of the liquid crystal compound is maintained. Specifically, it is more preferable that the layer has no fluidity and can stably maintain the fixed alignment without causing any change in the alignment due to an external field or external force, usually within a temperature range of 0 to 50°C, or under more severe conditions within a temperature range of -30 to 70°C.

[0026] The liquid crystal compound may be either a discotic liquid crystal compound or a rod-shaped liquid crystal compound. Known compounds can be used as the discotic liquid crystal compound. Examples of the discotic liquid crystal compound include the compounds described in paragraphs 0020 to 0067 of JP-A No. 2007-108732 and paragraphs 0013 to 0108 of JP-A No. 2010-244038. Known compounds can be used as the rod-shaped liquid crystal compound. Examples of the rod-shaped liquid crystal compound include the compounds described in claim 1 of JP-A No. 11-513019 and paragraphs 0026 to 0098 of JP-A No. 2005-289980.

[0027] The liquid crystal compound may have a polymerizable group, and is preferably a liquid crystal compound having a polymerizable group (polymerizable liquid crystal compound) in that the alignment can be fixed. In this specification, the type of the polymerizable group is not particularly limited, and a functional group capable of undergoing an addition polymerization reaction is preferred, a polymerizable ethylenically unsaturated group or a ring-polymerizable group is more preferred, and a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group is even more preferred.

[0028] The in-plane retardation of the first optically anisotropic layer at a wavelength of 550 nm is 150 nm or more, preferably 155 nm or more, more preferably 160 nm or more, in terms of providing a more excellent effect of the present invention. The in-plane retardation of the first optically anisotropic layer at a wavelength of 550 nm is 240 nm or less, preferably 220 nm or less, more preferably 200 nm or less, even more preferably 180 nm or less, in terms of providing a more excellent effect of the present invention.

[0029] The value (Re / d) obtained by dividing the in-plane retardation Re of the first optically anisotropic layer at a wavelength of 550 nm by the thickness d of the first optically anisotropic layer is 0.07 or more, preferably 0.08 or more, more preferably 0.09 or more, in terms of providing superior effects of the present invention. Re / d is 0.116 or less, preferably 0.113 or less, more preferably 0.110 or less, in terms of providing superior effects of the present invention. In other words, the refractive index anisotropy Δn of the first optically anisotropic layer at a wavelength of 550 nm is 0.07 to 0.116, preferably 0.09 to 0.11. If Re / d is less than 0.07, significant azimuthal dependence of color is observed, and alignment of the liquid crystal is poor, which is undesirable. If Re / d is more than 0.116, significant in-plane color unevenness is observed, which is undesirable.

[0030] The thickness of the first optically anisotropic layer is not particularly limited as long as Re / d satisfies the above requirement, but is preferably 0.5 μm or more, more preferably 1.0 μm or more, even more preferably 1.3 μm or more, and particularly preferably 1.4 μm or more. The thickness of the first optically anisotropic layer is preferably 5.0 μm or less, more preferably 3.0 μm or less, even more preferably 2.5 μm or less, and particularly preferably 2.2 μm or less. The thickness is determined by measuring the thickness of any five or more points of the first optically anisotropic layer and calculating the arithmetic average.

[0031] The average refractive index of the first optically anisotropic layer is preferably from 1.50 to 1.70, more preferably from 1.55 to 1.65, in that the layer can be made thinner and the effects of the present invention are more excellent.

[0032] The angle formed between the in-plane slow axis of the first optically anisotropic layer and the absorption axis of the polarizer is preferably from 40 to 85°, more preferably from 50 to 85°, and even more preferably from 65 to 85°.

[0033] The first optically anisotropic layer may be composed of one optically anisotropic layer or two or more optically anisotropic layers, and is preferably composed of one optically anisotropic layer in order to enable the optical film to be made thinner.

[0034] In order to obtain a more excellent effect of the present invention, the first optically anisotropic layer is preferably a layer formed using a composition containing a discotic liquid crystal compound, and more preferably a layer formed by fixing a vertically aligned discotic liquid crystal compound. The first optically anisotropic layer may be a layer formed using a composition containing a rod-shaped liquid crystal compound, and in this case, is preferably a layer formed by fixing a horizontally aligned rod-shaped liquid crystal compound.

[0035] <Adhesion Layer> The adhesion layer is not particularly limited as long as it has the function of adhering the first optically anisotropic layer and the second optically anisotropic layer to each other. For example, an adhesive layer or a pressure-sensitive adhesive layer can be used as the adhesion layer.

[0036] The adhesive layer is a layer formed using an adhesive. Examples of adhesives include active energy ray-curable adhesives, aqueous adhesives, solvent-based adhesives, emulsion-based adhesives, solventless adhesives, and thermosetting adhesives, with active energy ray-curable adhesives being preferred. Examples of active energy ray-curable adhesives include electron beam-curable adhesives, ultraviolet ray-curable adhesives, and visible light-curable adhesives, with ultraviolet ray-curable adhesives being preferred. Examples of active energy ray-curable adhesives include known adhesives, with adhesives selected from (meth)acrylate adhesives and epoxy adhesives being preferred. Examples of curable components in (meth)acrylate adhesives include compounds having a (meth)acryloyl group and compounds having a vinyl group. Examples of curable components in epoxy adhesives include compounds having a glycidyl group.

[0037] The method for forming the adhesive layer is not particularly limited, and examples thereof include a method in which an adhesive is applied to at least one layer selected from the first optically anisotropic layer and the second optically anisotropic layer, the first optically anisotropic layer and the second optically anisotropic layer are laminated together, and then the adhesive is cured. Examples of the application method include roll coating methods such as reverse coating and gravure coating, spin coating, screen coating, fountain coating, dipping, and spraying.

[0038] The pressure-sensitive adhesive layer is a layer containing a pressure-sensitive adhesive, and a known pressure-sensitive adhesive layer can be used. Examples of pressure-sensitive adhesives contained in the pressure-sensitive adhesive layer include acrylic pressure-sensitive adhesives, epoxy pressure-sensitive adhesives, rubber pressure-sensitive adhesives, silicone pressure-sensitive adhesives, urethane pressure-sensitive adhesives, vinyl alkyl ether pressure-sensitive adhesives, polyvinyl alcohol pressure-sensitive adhesives, polyvinylpyrrolidone pressure-sensitive adhesives, polyacrylamide pressure-sensitive adhesives, and cellulose pressure-sensitive adhesives. Among these, acrylic pressure-sensitive adhesives (pressure-sensitive adhesives) are preferred because of their excellent transparency, weather resistance, heat resistance, etc.

[0039] As the acrylic adhesive, a copolymer of a (meth)acrylate in which the alkyl group in the ester moiety is an alkyl group having 20 or less carbon atoms, such as a methyl group, an ethyl group, or a butyl group, and a (meth)acrylic monomer having a functional group, such as (meth)acrylic acid and hydroxyethyl (meth)acrylate, is preferred. As the adhesive, the contents of

[0071] to

[0084] of JP 2018-60014 A can be referred to, and the contents thereof are incorporated herein by reference.

[0040] The method for forming the adhesive layer is not particularly limited, and examples thereof include a method in which a solution of the adhesive is applied to a release sheet, dried, and then transferred to at least one layer selected from the first optically anisotropic layer and the second optically anisotropic layer, and a method in which a solution in which the adhesive is dissolved or dispersed in a solvent (e.g., toluene and ethyl acetate) is applied to the surface of at least one layer selected from the first optically anisotropic layer and the second optically anisotropic layer and then dried. The application method can be the same as the application method for adhesives. Examples of materials constituting the release sheet include suitable thin sheets such as synthetic polymer films such as polyethylene, polypropylene, and polyethylene terephthalate; rubber sheets; paper; cloth; nonwoven fabrics; nets; foam sheets; and metal foils.

[0041] The thickness of the adhesion layer is preferably 0.5 μm or more, more preferably 1 μm or more, and even more preferably 2 μm or more, from the viewpoint of achieving superior effects of the present invention. Furthermore, the thickness of the adhesion layer is preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less, from the viewpoint of achieving superior effects of the present invention. The thickness of the adhesion layer is calculated by measuring the reflectance of the optical film using a microspectrophotometer (OPTM, manufactured by Otsuka Electronics) (objective lens: 5x) and then performing a Fourier transform using the analysis software installed in the same device (calculated wavelength: 400-800 nm, Bell function: enabled). Specifically, peaks corresponding to the optical thicknesses of the optically anisotropic layers and adhesion layer are detected from the power spectrum calculated by Fourier transform under the above conditions, and the optical thickness of the adhesion layer is then divided by the refractive index of the adhesion layer to calculate the thickness of the adhesion layer. This measurement and calculation are performed at 1 mm intervals over a 3 cm area at any position on the optical film, and the average of the 31 calculation results is taken as the "thickness of the adhesion layer."

[0042] The thickness unevenness σ (unit: nm) of the adhesion layer is often 100 nm or less, and is preferably 35 nm or less, more preferably less than 10 nm, in order to achieve better effects of the present invention. Furthermore, the thickness unevenness σ of the adhesion layer is preferably 5 nm or more, in order to prevent air bubbles from being trapped when the first optically anisotropic layer and the second optically anisotropic layer are bonded together. That is, the thickness unevenness σ of the adhesion layer is preferably 5 to 35 nm, more preferably 5 nm or more and less than 10 nm. The thickness unevenness σ of the adhesion layer is a value calculated as the standard deviation of the thickness of the adhesion layer at 31 points obtained in the above-mentioned thickness measurement of the adhesion layer. The method for adjusting the thickness unevenness of the adhesion layer is not particularly limited, and examples include adjusting the composition, viscosity, and coating method of the composition forming the adhesion layer, as well as the conditions for bonding the first optically anisotropic layer and the second optically anisotropic layer via the adhesion layer.

[0043] The average refractive index of the adhesive layer is preferably 1.48 to 1.70, and more preferably 1.55 to 1.67, in terms of achieving better effects of the present invention. The absolute value of the difference between the average refractive index of the adhesive layer and the average refractive index of the first optically anisotropic layer is preferably 0 to 0.50, and more preferably 0 to 0.20, in terms of achieving better effects of the present invention.

[0044] <Second Optically Anisotropic Layer> The second optically anisotropic layer is preferably a layer formed using a composition containing an aligned liquid crystal compound, and more preferably a layer formed by fixing an aligned liquid crystal compound. Examples of the liquid crystal compound include the same liquid crystal compounds as those in the first optically anisotropic layer described above.

[0045] The product Δnd of the refractive index anisotropy Δn of the second optically anisotropic layer at a wavelength of 550 nm and the thickness d of the second optically anisotropic layer is preferably 100 nm or more, more preferably 105 nm or more, and even more preferably 110 nm or more. The value of Δnd is preferably 220 nm or less, more preferably 200 nm or less, and even more preferably 190 nm or less. The refractive index anisotropy Δn refers to the refractive index anisotropy of the optically anisotropic layer. The Δnd is measured using an Axometrics AxoScan (polarimeter) device and the device analysis software of the same company.

[0046] The thickness of the second optically anisotropic layer is preferably 0.5 μm or more, more preferably 0.8 μm or more, even more preferably 1.0 μm or more, and particularly preferably 1.5 μm or more, in order to obtain a more excellent effect of the present invention. The thickness of the second optically anisotropic layer is preferably 5.0 μm or less, more preferably 3.0 μm or less, and even more preferably 2.5 μm or less. The method for measuring the thickness of the second optically anisotropic layer is as described above.

[0047] The average refractive index of the second optically anisotropic layer is preferably from 1.50 to 1.70, more preferably from 1.55 to 1.65, in that the layer can be made thinner and the effects of the present invention are more excellent.

[0048] The second optically anisotropic layer may be composed of one optically anisotropic layer or may be composed of two or more optically anisotropic layers. In terms of more excellent effects of the present invention, the second optically anisotropic layer is preferably selected from a laminate (hereinafter also referred to as "optically anisotropic layer (AB)") of an optically anisotropic layer containing a twisted, helical axis-oriented rod-shaped liquid crystal compound fixed in the thickness direction (hereinafter also referred to as "optically anisotropic layer (A)") and an optically anisotropic layer containing a vertically aligned rod-shaped liquid crystal compound fixed in the thickness direction (hereinafter also referred to as "optically anisotropic layer (B)"), and an optically anisotropic layer containing a vertically aligned discotic liquid crystal compound fixed in the thickness direction (hereinafter also referred to as "optically anisotropic layer (C)"), and more preferably the optically anisotropic layer (AB).

[0049] (Optically anisotropic layer (AB)) The optically anisotropic layer (AB) is an optically anisotropic layer formed by laminating an optically anisotropic layer (A) and an optically anisotropic layer (B), and it is preferable that the optically anisotropic layer (A) and the optically anisotropic layer (B) are laminated in this order from the adhesive layer side.

[0050] -Optical Anisotropic Layer (A)- As described above, the optically anisotropic layer (A) is an optically anisotropic layer in which rod-like liquid crystal compounds are fixed in a twisted alignment with the thickness direction as the helical axis, and is preferably a layer in which a chiral nematic phase having a so-called helical structure is fixed.

[0051] The optically anisotropic layer (A) is preferably formed using a composition containing a rod-shaped liquid crystal compound exhibiting a nematic liquid crystal layer and a chiral agent described later. The rod-shaped liquid crystal compound is not particularly limited, and examples thereof include the rod-shaped liquid crystal compounds that can be contained in the first optically anisotropic layer described above.

[0052] The twist angle of the rod-shaped liquid crystal compound (the twist angle in the alignment axis direction of the liquid crystal compound) is not particularly limited, and is often greater than 0° and less than 360°. From the viewpoint of achieving superior effects of the present invention, 80±30° (in the range of 50 to 110°) is preferred, 80±20° (in the range of 60 to 100°) is more preferred, and 80±10° (in the range of 70 to 90°) is even more preferred. The twist angle is measured using an Axometrics AxoScan (polarimeter) device and the company's instrument analysis software. Twisted alignment of the liquid crystal compound refers to twisting of the liquid crystal compound from one main surface to the other main surface of the optically anisotropic layer (A) around the thickness direction of the optically anisotropic layer (A) as an axis. Accordingly, the alignment axis direction (in-plane slow axis direction) of the liquid crystal compound varies depending on the position in the thickness direction of the optically anisotropic layer (A).

[0053] The angle formed by the in-plane slow axis of the first optically anisotropic layer and the in-plane slow axis of the surface of the optically anisotropic layer (A) on the adhesive layer side is preferably from 0 to 20°, more preferably from 0 to 15°.

[0054] The value of the product Δnd of the refractive index anisotropy Δn of the optically anisotropic layer (A) at a wavelength of 550 nm and the thickness d of the optically anisotropic layer (A) is preferably 140 nm or more, more preferably 150 nm or more, and even more preferably 160 nm or more. The value of Δnd is preferably 220 nm or less, more preferably 210 nm or less, and even more preferably 200 nm or less. The method for determining Δnd is as described above.

[0055] The thickness of the optically anisotropic layer (A) is not particularly limited, but is preferably 0.5 μm or more, more preferably 1.0 μm or more, and even more preferably 1.3 μm or more. The thickness of the optically anisotropic layer (A) is preferably 5.0 μm or less, more preferably 2.5 μm or less, and even more preferably 2.2 μm or less. The thickness is determined by measuring the thickness at any five or more points of the optically anisotropic layer (A) and calculating the arithmetic average.

[0056] -Optical Anisotropic Layer (B)- As described above, the optically anisotropic layer (B) is a layer in which vertically aligned rod-like liquid crystal compounds are fixed.

[0057] The optically anisotropic layer (B) is preferably formed using a composition containing a rod-shaped liquid crystal compound and a photoalignable polymer described later. The rod-shaped liquid crystal compound is not particularly limited, and examples thereof include the liquid crystal compounds that can be contained in the first optically anisotropic layer described above.

[0058] The in-plane retardation of the optically anisotropic layer (B) at a wavelength of 550 nm is preferably 0 to 10 nm, more preferably 0 to 5 nm. The thickness direction retardation of the optically anisotropic layer (B) at a wavelength of 550 nm is preferably −120 nm or more, more preferably −110 nm or more, and even more preferably −100 nm or more. The thickness direction retardation of the optically anisotropic layer (B) at a wavelength of 550 nm is preferably −20 nm or less, more preferably −30 nm or less, and even more preferably −40 nm or less.

[0059] The thickness of the optically anisotropic layer (B) is not particularly limited, but is preferably 10.0 μm or less, more preferably 5.0 μm or less, and even more preferably 2.0 μm or less. The thickness of the optically anisotropic layer (B) is preferably 0.1 μm or more, more preferably 0.3 μm or more. The thickness is determined by measuring the thickness at any five or more points of the optically anisotropic layer (B) and calculating the arithmetic average.

[0060] (Optically Anisotropic Layer (C)) As described above, the optically anisotropic layer (C) is a layer in which vertically aligned discotic liquid crystal compounds are fixed.

[0061] The discotic liquid crystal compound is not particularly limited, and examples thereof include the discotic liquid crystal compounds that can be contained in the first optically anisotropic layer described above.

[0062] The angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (C) is preferably 0 to 30°, more preferably 5 to 25°, and even more preferably 10 to 20°. The angle between the in-plane slow axis of the first optically anisotropic layer and the in-plane slow axis of the optically anisotropic layer (C) is preferably 60±30° (within the range of 30 to 90°), more preferably 60±20° (within the range of 40 to 80°), and even more preferably 60±10° (within the range of 50 to 70°).

[0063] The in-plane retardation of the optically anisotropic layer (C) at a wavelength of 550 nm is preferably 100 nm or more, more preferably 105 nm or more, and is preferably 150 nm or less, more preferably 145 nm or less.

[0064] The thickness of the optically anisotropic layer (C) is not particularly limited, but is preferably 10.0 μm or less, more preferably 5.0 μm or less, and even more preferably 2.0 μm or less. The thickness of the optically anisotropic layer (C) is preferably 0.1 μm or more, more preferably 0.3 μm or more. The thickness is determined by measuring the thickness at any five or more points of the optically anisotropic layer (C) and calculating the arithmetic average.

[0065] <Other Layers> The optical film may include layers other than the first optically anisotropic layer, the adhesive layer, and the second optically anisotropic layer described above, as long as the layers do not impair the functions of the present invention. Examples of the other layers include an optically anisotropic layer different from the first optically anisotropic layer and the second optically anisotropic layer described above, and an adhesive layer.

[0066] It is also preferable to dispose a third optically anisotropic layer between the polarizer and the first optically anisotropic layer. That is, it is also preferable that the optical film has a third optically anisotropic layer on the polarizer-side surface of the first optically anisotropic layer. The third optically anisotropic layer is preferably a layer formed using a composition containing an aligned liquid crystal compound, more preferably a layer formed by fixing an aligned liquid crystal compound. Examples of the liquid crystal compound include the same liquid crystal compounds as those in the first optically anisotropic layer described above. The third optically anisotropic layer is preferably a layer formed by fixing a horizontally aligned discotic liquid crystal compound. By using such a layer, color change when viewed from an oblique direction can be further reduced, thereby achieving good visibility. In this case, it is also preferable to use an adhesion layer as described above to bond the polarizer and the third optically anisotropic layer, and the third optically anisotropic layer and the first optically anisotropic layer. From the viewpoint of suppressing interfacial reflection, it is also preferable to form the optically anisotropic layer by directly laminating and coating the composition for forming the optically anisotropic layer, or to perform plasma lamination, without disposing an adhesion layer. It is also preferable to provide a gradient in refractive index from the inside to the surface of the liquid crystal layer (optically anisotropic layer). These interfacial reflection suppression techniques may be applied to any of the optically anisotropic layers of the optical film, and are even more effective when applied to the first optically anisotropic layer and the second optically anisotropic layer.

[0067] The in-plane retardation of the third optically anisotropic layer at a wavelength of 550 nm is preferably 0 to 10 nm, more preferably 0 to 5 nm. The thickness direction retardation of the third optically anisotropic layer at a wavelength of 550 nm is preferably 10 nm to 100 nm, more preferably 20 nm to 80 nm, and even more preferably 20 nm to 50 nm.

[0068] The thickness of the third optically anisotropic layer is not particularly limited, and is preferably from 0.1 μm to 10.0 μm, more preferably from 0.3 μm to 5.0 μm, and even more preferably from 0.3 μm to 2.0 μm. The thickness is determined by measuring the thickness of the third optically anisotropic layer at any five or more points and arithmetically averaging the measured values.

[0069] The third optically anisotropic layer and the polarizer, and the third optically anisotropic layer and the first optically anisotropic layer are disposed directly or via an adhesive layer. Examples of the adhesive layer include the adhesive layer described above. On one or both surfaces of the third optically anisotropic layer, the difference between the refractive index (average refractive index) of the surface of the third optically anisotropic layer and the refractive index (average refractive index) of the adjacent layer is preferably 0.20 or less, more preferably 0.10 or less, and even more preferably 0.05 or less.

[0070] [Polarizer] The polarizer of the polarizing plate of the present invention may be any component capable of converting natural light into specific linearly polarized light, and may be, for example, an absorptive polarizer. The type of polarizer is not particularly limited, and commonly used polarizers may be used, such as iodine-based polarizers, dye-based polarizers using dichroic dyes, and polyene-based polarizers. Iodine-based polarizers and dye-based polarizers are generally produced by adsorbing iodine or a dichroic dye into polyvinyl alcohol and stretching the resulting mixture. A protective film may be disposed on one or both sides of the polarizer.

[0071] Furthermore, as described in WO 2019 / 131943 and JP 2017-083843 A, a coating-type polarizer may be used that is prepared by coating a liquid crystal compound and a dichroic organic dye (for example, a dichroic azo dye used in the light-absorbing anisotropic film described in WO 2017 / 195833 A) without using polyvinyl alcohol as a binder. That is, the polarizer may be a polarizer formed using a composition containing a polymerizable liquid crystal compound. This coating-type polarizer utilizes the orientation of the liquid crystal compound to orient the dichroic organic dye. As described in JP 2012-083734 A, it is preferable for the polymerizable liquid crystal compound to exhibit smectic properties in order to increase the degree of orientation. Alternatively, as described in WO 2018 / 186503 A, crystallizing the dye is also preferable in order to increase the degree of orientation. WO 2019 / 131943 describes a preferred structure of a polymer liquid crystal for increasing the degree of orientation.

[0072] Polarizers in which a dichroic organic dye is oriented without stretching, utilizing the orientation properties of liquid crystals, have the following characteristics. They have many advantages, including the ability to be made extremely thin, approximately 0.1 to 5 μm thick; resistance to cracking when bent and minimal thermal deformation, as described in JP 2019-194685 A; and excellent durability even for polarizing plates with high transmittance of over 50%, as described in Japanese Patent No. 6483486 A. These advantages can be utilized in applications requiring high brightness and compactness and light weight, in fine optical systems, for molding into curved surfaces, and for flexible components. Furthermore, polarizers can also be used by peeling off the support and transferring the polarizer.

[0073] The polarizing plate may have a polarizer protective film (polarizer protective film). The configuration of the polarizer protective film is not particularly limited and may be either a support or a coating layer of a polarizer, or a laminate of a support and a coating layer. Known layers can be used as the coating layer, including, for example, layers obtained by polymerizing and curing a polymer and a polyfunctional monomer. Examples of polymers include (meth)acrylic polymers and cycloolefin polymers. Examples of polymerizable monomers include radically polymerizable or cationically polymerizable compounds. The support may also function as an optically anisotropic layer. When the support functions as an optically anisotropic layer, the in-plane retardation of the support at a wavelength of 550 nm is preferably 0 to 10 nm, more preferably 0 to 5 nm. The retardation in the thickness direction at a wavelength of 550 nm is preferably 10 to 100 nm, more preferably 20 to 80 nm, and even more preferably 20 to 50 nm.

[0074] [Other Components] The polarizing plate may include other components in addition to the polarizer and the optical film, such as an alignment film and a substrate, as long as the effects of the present invention are not impaired.

[0075] <Alignment Film> The polarizing plate may have an alignment film. The alignment film may be disposed on a substrate described below or between optically anisotropic layers. The alignment film may be formed by rubbing an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having microgrooves, or accumulation of an organic compound (e.g., ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearate) using the Langmuir-Blodgett method (LB film). In addition to the above, the alignment film may be one that exhibits alignment function upon application of an electric field, a magnetic field, or light irradiation (preferably polarized light). Examples of the alignment film include photo-alignment films. When a photo-alignment film is used, rubbing is unnecessary and defects such as those caused by rubbing debris do not occur, making it possible to obtain a liquid crystal cured film with few defects as an optically anisotropic layer. While known compounds can be used for the photo-alignment film, it is preferable to use a polymer having a cinnamoyl structure as described in WO 2019 / 225632. The thickness of the alignment film is not particularly limited as long as it can exhibit its alignment function, but is preferably 0.01 to 5.0 μm, more preferably 0.05 to 3.0 μm, and even more preferably 0.5 to 1.0 μm. When the alignment film is disposed on a substrate, it may be peelable from the optically anisotropic layer together with the substrate.

[0076] <Substrate> The polarizing plate may have a substrate. The substrate is preferably a transparent substrate. The transparent substrate refers to a substrate having a visible light transmittance (average transmittance in the visible light region) of 60% or more, preferably 80% or more, and more preferably 90% or more. There is no particular upper limit, but 99.9% or less is preferred. There is no particular limit on the thickness of the substrate, but it is preferably 10 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 90 μm.

[0077] The substrate may contain various additives (for example, an optical anisotropy adjuster, a wavelength dispersion adjuster, fine particles, a plasticizer, an ultraviolet inhibitor, a deterioration inhibitor, a release agent, etc.) The thickness of the substrate is not particularly limited, but is preferably 10 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 90 μm.

[0078] The substrate may be composed of a plurality of laminated sheets. Furthermore, the surface of the substrate may be subjected to a surface treatment (e.g., glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, or flame treatment) to improve adhesion with a layer provided thereon. An adhesive layer (undercoat layer) may be provided on the substrate. Furthermore, a polymer layer containing 5 to 40% by mass of inorganic particles with an average particle size of approximately 10 to 100 nm mixed therein in a solid content ratio by mass may be disposed on one side of the substrate to impart slipperiness during the transport process or to prevent sticking of the back and front surfaces after winding.

[0079] The substrate may be a so-called temporary support, that is, after the polarizing plate of the present invention is produced on the substrate, the substrate may be peeled off from the optically anisotropic layer, if necessary.

[0080] When forming the above-described alignment film on the substrate surface, the surface of the substrate may be directly subjected to a rubbing treatment. That is, a substrate that has been subjected to a rubbing treatment may be used. The direction of the rubbing treatment is not particularly limited, and an optimal direction may be selected as appropriate depending on the direction in which the liquid crystal compound is desired to be aligned. The rubbing treatment may be a treatment method that is widely used as a liquid crystal alignment treatment process for LCDs (liquid crystal displays). That is, a method of obtaining alignment by rubbing the surface of the substrate in a certain direction using paper, gauze, felt, rubber, nylon fiber, polyester fiber, or the like may be used.

[0081] [Preferred Embodiments of Polarizing Plate] In the polarizing plate of the present invention, the combination of the first optically anisotropic layer and the second optically anisotropic layer in the optical film is appropriately selected within a range that satisfies the requirements of the present invention, but the polarizing plate of the following Embodiment 1 or Embodiment 2 is preferred, and the polarizing plate of Embodiment 1 is more preferred in that the color tone during black display can be further suppressed. (Embodiment 1) The first optically anisotropic layer is a layer formed by fixing a vertically aligned discotic liquid crystal compound, and the second optically anisotropic layer is the optically anisotropic layer (AB). (Embodiment 2) The first optically anisotropic layer is a layer formed by fixing a vertically aligned discotic liquid crystal compound or a layer formed by fixing a horizontally aligned rod-shaped liquid crystal compound, and the second optically anisotropic layer is the optically anisotropic layer (C). In each embodiment, the definitions and preferred embodiments of the layer in which vertically aligned discotic liquid crystal compounds are fixed, the optically anisotropic layer (AB), the layer in which horizontally aligned rod-shaped liquid crystal compounds are fixed, and the optically anisotropic layer (C) are as described above.

[0082] The polarizing plate of the above-mentioned embodiment 1 will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic cross-sectional view of a polarizing plate 100A of embodiment 1. FIG. 2 is a diagram showing the relationship between the absorption axis of a polarizer 30A and the in-plane slow axes of the first optically anisotropic layer 12A and the optically anisotropic layer (B) 14A in the polarizing plate 100A of embodiment 1 shown in FIG. 1. Note that the arrows in the polarizer 30A in FIG. 2 represent the absorption axis, and the arrows in the first optically anisotropic layer 12A and the optically anisotropic layer (B) 14A represent the in-plane slow axes in the layers, respectively. FIG. 3 is a diagram showing the relationship between the absorption axis of the polarizer 30A (dashed line) and the in-plane slow axes (solid lines) of the first optically anisotropic layer 12A and the optically anisotropic layer (A) 14A when observed from the side indicated by the white arrow in FIG. 1. The rotation angle of the in-plane slow axis is expressed as a positive angle in the counterclockwise direction and a negative angle in the clockwise direction, with the absorption axis of polarizer 30A as the reference (0°) when observed from the side indicated by the white arrow in Fig. 1. The twist direction of the liquid crystal compound is determined as right-handed (clockwise) or left-handed (counterclockwise) based on the in-plane slow axis on the surface of optically anisotropic layer (A) 14A facing polarizer 30A when observed from the side indicated by the white arrow in Fig. 1.

[0083] 1, the polarizing plate 100A of the first embodiment has a polarizer 30A, a first optically anisotropic layer 12A, an adhesive layer 40A, an optically anisotropic layer (A) 14A, and an optically anisotropic layer (B) 16A, in this order. A laminate of the optically anisotropic layer (A) 14A and the optically anisotropic layer (B) 16A constitutes a second optically anisotropic layer. The polarizing plate 100A may have an adhesive layer (not shown) between the polarizer 30A and the first optically anisotropic layer 14A, or may have an optically anisotropic layer (e.g., a third optically anisotropic layer) (not shown).

[0084] In the polarizing plate 100A of the first embodiment, as shown in Figures 2 and 3, the angle φa1 between the absorption axis of the polarizer 30A and the first optically anisotropic layer 12A is 76°. More specifically, the in-plane slow axis of the first optically anisotropic layer 12A is rotated by -76° (76° clockwise) with respect to the absorption axis of the polarizer 30. Although Figures 2 and 3 show an embodiment in which φa1 is 76°, the present invention is not limited to this embodiment, and φa1 is preferably 40 to 85°, more preferably 50 to 85°, and even more preferably 65 to 85°. As shown in FIG. 2, in the first optically anisotropic layer 12A, the in-plane slow axis at the surface 121A of the first optically anisotropic layer 12A facing the polarizer 30A is parallel to the in-plane slow axis at the surface 122A of the first optically anisotropic layer 12A facing the optically anisotropic layer (A) 14A.

[0085] 2 and 3, the in-plane slow axis of the optically anisotropic layer (A) 14 at its surface 141A facing the first optically anisotropic layer 12A is parallel to the in-plane slow axis of the first optically anisotropic layer 12A. As described above, the optically anisotropic layer (A) 14A is a layer formed by fixing rod-shaped liquid crystal compounds that are twisted and aligned with the thickness direction as the helical axis. Therefore, as shown in FIGS. 2 and 3, the in-plane slow axis of the optically anisotropic layer (A) 14A at its surface 141A facing the first optically anisotropic layer 12A and the in-plane slow axis of the optically anisotropic layer (B) 16A form the twist angle described above (81° in FIG. 2). That is, the angle φa2 formed between the in-plane slow axis of the surface 141A of the optically anisotropic layer (A) 14A facing the first optically anisotropic layer 12A and the in-plane slow axis of the surface 142A facing the optically anisotropic layer (B) 16A is 81°. More specifically, the twist direction of the rod-shaped liquid crystal compound in the optically anisotropic layer (A) 14 is left-handed (counterclockwise), and the twist angle is 81°. While FIGS. 2 and 3 show an embodiment in which the twist angle of the rod-shaped liquid crystal compound in the optically anisotropic layer (A) 14A is 81°, the twist angle is not limited to this embodiment, and the twist angle of the rod-shaped liquid crystal compound is preferably within the range of 80±30°, more preferably within the range of 80±20°, and even more preferably within the range of 80±10°.

[0086] As described above, in the embodiments shown in Figures 2 and 3, when the polarizing plate 100A is observed from the polarizer 30A side, the in-plane slow axis of the first optically anisotropic layer 12A is rotated 76° clockwise with respect to the absorption axis of the polarizer 30A, and the twist direction of the rod-shaped liquid crystal compound in the optically anisotropic layer (A) 14A is counterclockwise (left-handed twist). Although the embodiments shown in Figures 2 and 3 have been described in detail with the rod-shaped liquid crystal compound twisted counterclockwise, they may also be twisted clockwise as long as a predetermined angular relationship is satisfied. More specifically, when the polarizing plate 100A is observed from the polarizer 30A side, the in-plane slow axis of the first optically anisotropic layer 12A is rotated 76° counterclockwise with respect to the absorption axis of the polarizer 30A, and the twist direction of the rod-shaped liquid crystal compound in the optically anisotropic layer (B) 14A may be clockwise (right-handed twist).

[0087] That is, in polarizing plate 100A, when the in-plane slow axis of the first optically anisotropic layer rotates clockwise within a range of 40 to 85° (preferably 50 to 85°, more preferably 65 to 85°) with respect to the absorption axis of polarizer 30A, it is preferable that the twist direction of the rod-shaped liquid crystal compound in optically anisotropic layer (A) is counterclockwise with respect to the in-plane slow axis at the surface of optically anisotropic layer (A) facing the first optically anisotropic layer. Also, in polarizing plate 100A, when the in-plane slow axis of the first optically anisotropic layer rotates counterclockwise within a range of 40 to 85° (preferably 50 to 85°, more preferably 65 to 85°) with respect to the absorption axis of polarizer 30A, it is preferable that the twist direction of the rod-shaped liquid crystal compound in optically anisotropic layer (A) is clockwise with respect to the in-plane slow axis at the surface of optically anisotropic layer (A) facing the first optically anisotropic layer.

[0088] The polarizing plate of the second embodiment described above will be described with reference to FIGS. 4 to 6. FIG. 4 is a schematic cross-sectional view of a polarizing plate 100B of the second embodiment. FIG. 5 is a diagram showing the relationship between the absorption axis of the polarizer 30B and the in-plane slow axes of the first optically anisotropic layer 12B and the optically anisotropic layer (C) 18B in the polarizing plate 100B of the second embodiment shown in FIG. 4. Note that the arrows in the polarizer 30B in FIG. 2 represent the absorption axis, and the arrows in the first optically anisotropic layer 12B and the optically anisotropic layer (C) 18B represent the in-plane slow axes in the layers, respectively. FIG. 6 is a diagram showing the relationship between the absorption axis of the polarizer 30B (dashed line) and the in-plane slow axes (solid lines) of the first optically anisotropic layer 12B and the optically anisotropic layer (C) 18B when observed from the side indicated by the white arrow in FIG. 4. The rotation angle of the in-plane slow axis is expressed as a positive angle in the counterclockwise direction and a negative angle in the clockwise direction when observed from the side indicated by the white arrow in Figure 4, with the absorption axis of polarizer 30B as the reference (0°).

[0089] 4, the polarizing plate 100B of the second embodiment includes a polarizer 30B, a first optically anisotropic layer 12B, an adhesive layer 40B, and an optically anisotropic layer (C) 18B in this order. The polarizing plate 100B may include an adhesive layer (not shown) between the polarizer 30B and the first optically anisotropic layer 12B, or may include an optically anisotropic layer (e.g., a third optically anisotropic layer) (not shown).

[0090] In the polarizing plate 100B of the second embodiment, as shown in Figures 5 and 6, the angle φa3 between the absorption axis of the polarizer 30B and the first optically anisotropic layer 12B is 73°. More specifically, the in-plane slow axis of the first optically anisotropic layer 12B is rotated by -73° (73° clockwise) with respect to the absorption axis of the polarizer 30B. Although Figures 5 and 6 show an embodiment in which φa3 is 73°, the present invention is not limited to this embodiment, and φa3 is preferably 40 to 85°, more preferably 50 to 85°, and even more preferably 65 to 85°. Furthermore, as shown in Figure 5, in the first optically anisotropic layer 12B, the in-plane slow axis at the surface 121B of the first optically anisotropic layer 12B facing the polarizer 30B is parallel to the in-plane slow axis at the surface 122B of the first optically anisotropic layer 12B facing the optically anisotropic layer (C) 18B.

[0091] As shown in Figures 5 and 6, the angle φa4 between the in-plane slow axis of the first optically anisotropic layer 12B and the in-plane slow axis of the optically anisotropic layer (C) 18B is 58°. More specifically, the in-plane slow axis of the optically anisotropic layer (C) 18B is rotated by 58° (58° counterclockwise) with respect to the in-plane slow axis of the first optically anisotropic layer 12B. Note that although Figures 5 and 6 show an embodiment in which φa4 is 58°, the present invention is not limited to this embodiment, and φa4 is preferably 60±30°, more preferably 60±20°, and even more preferably 60±10°. As shown in FIG. 5, in the optically anisotropic layer (C) 18B, the in-plane slow axis at a surface 181 of the optically anisotropic layer (C) 18B facing the first optically anisotropic layer 12B is parallel to the in-plane slow axis at a surface 182 of the optically anisotropic layer (C) 18B facing away from the first optically anisotropic layer 12B.

[0092] 4 to 6 illustrate an embodiment in which the in-plane slow axis of the first optically anisotropic layer 12B rotates clockwise with respect to the absorption axis of the polarizer 30B when the polarizing plate 100B is observed from the polarizer 30B side, but the in-plane slow axis may rotate counterclockwise within a range of 40 to 85° (preferably 50 to 85°, more preferably 65 to 85°). For example, when the polarizing plate 100B is observed from the polarizer 30B side, if the in-plane slow axis of the first optically anisotropic layer 12B rotates counterclockwise within a range of 40 to 85° with respect to the absorption axis of the polarizer 30B, the in-plane slow axis of the optically anisotropic layer (C) 18B preferably rotates clockwise within a range of 60±30° with respect to the in-plane slow axis of the first optically anisotropic layer 12B.

[0093] [Method for manufacturing polarizing plate] The method for manufacturing a polarizing plate is not particularly limited, and known methods can be used. For example, a polarizing plate can be manufactured by separately manufacturing a polarizer and an optical film and bonding them in a predetermined direction via an adhesive layer. The method for manufacturing the polarizer is as described above. The adhesive layer that adheres the polarizer and the optical film is not particularly limited, and known adhesive layers and pressure-sensitive adhesive layers can be used, and for example, the adhesive layers exemplified as the adhesive layers in the optical film described above can be used.

[0094] The optical film may be formed by any known method as long as the first optically anisotropic layer, the adhesive layer, and the second optically anisotropic layer are laminated in this order. For example, the first optically anisotropic layer and the second optically anisotropic layer may be separately prepared and then bonded together via the adhesive layer. The method for bonding the first optically anisotropic layer and the second optically anisotropic layer via the adhesive layer is not particularly limited, and any known method may be used.

[0095] When the adhesive layer is an adhesive layer, it is preferable to subject the adhesive layer to a curing treatment after lamination. The curing method can be appropriately selected depending on the type of adhesive layer, and examples thereof include heat treatment and active energy ray irradiation treatment. Before forming and laminating the adhesive layer, each optically anisotropic layer (e.g., the first optically anisotropic layer and the second optically anisotropic layer) may be subjected to a surface treatment (e.g., glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment) to improve adhesion.

[0096] The first optically anisotropic layer, the second optically anisotropic layer, and the third optically anisotropic layer can be prepared using, for example, a composition for forming an optically anisotropic layer containing a liquid crystal compound. Hereinafter, a method for forming an optically anisotropic layer using a composition for forming an optically anisotropic layer will be described in detail.

[0097] <Method for Producing Optically Anisotropic Layer> The optically anisotropic layer can be formed using a composition for forming an optically anisotropic layer.

[0098] (Composition for forming optically anisotropic layer) The liquid crystal compound contained in the composition for forming an optically anisotropic layer is the same as the liquid crystal compound contained in each of the optically anisotropic layers described above. As described above, a rod-shaped liquid crystal compound or a discotic liquid crystal compound is appropriately selected depending on the properties of the optically anisotropic layer to be formed. As described above, the liquid crystal compound is preferably a polymerizable liquid crystal compound having a polymerizable group. The polymerizable group is as described above. The content of the liquid crystal compound in the composition for forming an optically anisotropic layer is preferably 60 to 99% by mass, more preferably 70 to 98% by mass, based on the total solid content of the composition for forming an optically anisotropic layer. Note that the solid content refers to components capable of forming an optically anisotropic layer from which the solvent has been removed, and is considered to be solid content even if the component is in a liquid state.

[0099] The composition for forming an optically anisotropic layer may contain compounds other than the liquid crystal compound, such as a chiral agent, a photoalignment compound (photoalignment polymer), a polymerization initiator, a polyfunctional monomer, an alignment control agent (vertical alignment agent, horizontal alignment agent), a surfactant, an adhesion improver, a plasticizer, and a solvent.

[0100] For example, the composition for forming the optically anisotropic layer (A) preferably contains a chiral agent to helically align the liquid crystal compound. Note that when the liquid crystal compound is an optically active compound, such as one having an asymmetric carbon in the molecule, the addition of a chiral agent is unnecessary. Also, depending on the production method and twist angle, the addition of a chiral agent is unnecessary. The chiral agent is not particularly limited as long as it is compatible with the liquid crystal compound used in combination, and known chiral agents can be used, and may be appropriately selected depending on the sense and pitch of the desired helix. Examples of chiral agents that can be used include compounds described in "Liquid Crystal Device Handbook" (Chapter 3, Section 4-3, Chiral Agents for TN and STN, page 199, edited by the 142nd Committee of the Japan Society for the Promotion of Science, 1989), as well as JP-A Nos. 2003-287623, 2002-302487, 2002-080478, 2002-080851, 2010-181852, and 2014-034581. Of these, compounds selected from the group consisting of isosorbide derivatives, isomannide derivatives, and binaphthyl derivatives are preferred. Commercially available isosorbide derivatives, such as LC-756 manufactured by BASF, may also be used.

[0101] The chiral agent may have a polymerizable group. Examples of the polymerizable group that the chiral agent may have include the polymerizable groups that the liquid crystal compound may have, and preferred embodiments are also the same as those mentioned above.

[0102] The content of the chiral agent is preferably 0.01 to 200 mol %, more preferably 1 to 30 mol %, based on the content of the liquid crystal compound.

[0103] The photo-alignable compound is a compound having a photo-alignable group, and the photo-alignable group can be aligned in a predetermined direction by light irradiation. As the photo-alignable compound, a photo-alignable polymer is preferred. The photo-alignable polymer is not particularly limited as long as it is compatible with the liquid crystal compound used in combination, and known photo-alignable polymers can be used.

[0104] The composition for forming an optically anisotropic layer may contain a polymerization initiator. The polymerization initiator to be used is selected depending on the type of polymerization reaction, and examples thereof include a thermal polymerization initiator and a photopolymerization initiator. The content of the polymerization initiator in the composition for forming an optically anisotropic layer is preferably 0.01 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total solid content of the composition for forming an optically anisotropic layer.

[0105] (Procedure for Forming Optically Anisotropic Layer) The procedure for forming the optically anisotropic layer is not particularly limited. For example, a method can be used in which the above-described optically anisotropic layer-forming composition is applied to a substrate, the resulting coating is subjected to an alignment treatment to align the liquid crystal compound, and then the coating is cured to fix the liquid crystal compound. Examples of the substrate include the substrate that may be included in the polarizing plate described above. Alternatively, the optically anisotropic layer can be formed directly on the optically anisotropic layer using the optically anisotropic layer-forming composition. That is, by applying the optically anisotropic layer-forming composition to the prepared optically anisotropic layer and performing a predetermined treatment to form the optically anisotropic layer, a laminate can be produced in which two or more optically anisotropic layers are directly laminated without an adhesive layer. When the optically anisotropic layer is formed directly on the optically anisotropic layer using the optically anisotropic layer-forming composition, a treatment to form an alignment film can be performed on the surface of the optically anisotropic layer before applying the optically anisotropic layer-forming composition.

[0106] The coating method is not particularly limited, and examples thereof include extrusion coating, curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, die coating, and wire bar coating. If necessary, after coating the composition for forming an optically anisotropic layer, a treatment for drying the coating film coated on the substrate may be carried out. The drying treatment can remove the solvent from the coating film. The thickness of the coating film is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and even more preferably 0.5 to 10 μm.

[0107] The alignment treatment can be carried out by drying the coating film at room temperature or by heating the coating film. In the case of a thermotropic liquid crystal compound, the liquid crystal phase formed by the alignment treatment can generally be transitioned by a change in temperature or pressure. In the case of a lyotropic liquid crystal compound, the transition can also be achieved by adjusting the composition ratio, such as the amount of solvent. The conditions for heating the coating film are not particularly limited, but the heating temperature is preferably 50 to 250°C, more preferably 50 to 150°C, and the heating time is preferably 10 seconds to 10 minutes. After heating the coating film, the coating film may be cooled, if necessary, before the curing treatment (light irradiation treatment) described below. The cooling temperature is preferably 20 to 200°C, more preferably 30 to 150°C.

[0108] The curing method is not particularly limited, and examples thereof include light irradiation and heat treatment. Of these, light irradiation is preferred from the viewpoint of manufacturability, and ultraviolet irradiation is more preferred. The irradiation conditions for the light irradiation are not particularly limited, but are preferably 50 to 1000 mJ / cm. ２ The atmosphere during the light irradiation treatment is not particularly limited, but a nitrogen atmosphere is preferred.

[0109] When the composition for forming an optically anisotropic layer contains a photoalignable polymer, it is preferable to subject the composition to a photoalignment treatment in order to impart alignment controllability. Examples of the photoalignment treatment include a method of irradiating a coating film (including a cured film that has been cured) of the composition for forming an optically anisotropic layer with polarized light and a method of irradiating the coating film surface with non-polarized light from an oblique direction.

[0110] The wavelength of the polarized or unpolarized light is not particularly limited as long as it is light to which the photo-alignable group is photosensitive, and examples thereof include ultraviolet light, near ultraviolet light, and visible light, with near ultraviolet light of 250 to 450 nm being preferred. Examples of light sources for irradiating polarized or unpolarized light include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps. The wavelength range of the irradiated ultraviolet or visible light obtained from the light source can be limited by using an interference filter or color filter. Linearly polarized light can be obtained by using a polarizing filter or polarizing prism on the light from these light sources.

[0111] The integrated amount of polarized or unpolarized light is not particularly limited, and is 1 to 300 mJ / cm ２ is preferred, and 5 to 100 mJ / cm ２ The illuminance of polarized or unpolarized light is not particularly limited, and is 0.1 to 300 mW / cm ２ is preferred, and 1 to 100 mW / cm ２ is more preferred.

[0112] [Uses] The polarizing plate of the present invention can be suitably applied to a display device. The display device of the present invention includes a display element and the polarizing plate of the present invention. The polarizing plate is usually provided on the viewing side of the display device. In this case, the polarizer in the polarizing plate is arranged on the viewing side. The display element is not particularly limited, and examples thereof include an organic electroluminescence display element (organic EL display element) and a liquid crystal display element.

[0113] The organic electroluminescence display element is a member in which a light-emitting layer or a plurality of organic compound thin films including a light-emitting layer are formed between a pair of electrodes, an anode and a cathode, and may have a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and / or a protective layer in addition to the light-emitting layer, and each of these layers may have other functions. Various materials can be used to form each layer.

[0114] The polarizing plate of the present invention is thin and can be used in a variety of applications, including curved surfaces, flexible applications, and foldable applications. Furthermore, due to its excellent durability and high design flexibility, it is also suitable for use in automotive applications. Due to its characteristics, organic EL display elements tend to exhibit a "burn-in" phenomenon caused by element degradation when displayed for a long period of time. This is particularly problematic when used at extreme temperatures, such as in automotive applications. The polarizing plate of the present invention has excellent visibility from oblique directions, few defects, and excellent display performance. Furthermore, it can reduce the visibility of display unevenness caused by burn-in of the display element. Therefore, it can be used not only in small-sized display devices such as smartphones, but also in large-sized display devices such as monitors and tablets that require a long life.

[0115] [Robustness Design for Color Change] The polarizing plate of the present invention is characterized by minimal color change with azimuth angle when viewed from an oblique direction (small change distance on the chromaticity diagram). On the other hand, when color changes in a certain region due to changes in the performance of the circular polarizing plate caused by durability changes, changes in other components of the display device (burn-in, etc.), and differences due to manufacturing variations, the color may change to a different quadrant on the chromaticity diagram, resulting in a noticeable change in the apparent color. In response to this, it is effective to set the color so that it changes within the same quadrant on the chromaticity diagram before and after the above-mentioned change, and this can be adopted as a design with excellent robustness to color change.

[0116] [Other Configurations] It is also preferable from the viewpoint of protecting the polarizing plate to provide a hard coat layer, a cover glass, an ultra-thin glass, or a hard film composed of a hard coat layer and a support on the surface opposite to the optically anisotropic layer (optical film) side of the polarizing plate of the present invention. In addition, a low refractive index layer or an AR layer in which high refractive index layers and low refractive index layers are alternately laminated is provided on the viewing side surface of the hard coat layer and the glass to reduce the reflectance of the surface, thereby further improving visibility.

[0117] The present invention will be described in more detail below with reference to the following examples. The materials, amounts used, ratios, treatment details, and treatment procedures shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.

[0118] [Example 1] <Preparation of Cellulose Acylate Film (Substrate)> The following composition (cellulose acylate dope) was charged into a mixing tank, stirred, and further heated at 90°C for 10 minutes. Thereafter, the obtained composition was filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm to prepare a dope. The solid content concentration of the dope was 23.5 mass%, the amount of plasticizer added was the ratio relative to the cellulose acylate, and the solvent for the dope was methylene chloride / methanol / butanol = 81 / 18 / 1 (mass ratio).

[0119] ------------------------------- Cellulose acylate dope -------------------------------- Cellulose acylate (acetyl substitution degree 2.86, viscosity average polymerization degree 310) 100 parts by mass Compound 1 (shown in the following formula (S4)) 8.0 parts by mass Compound 2 (shown in the following formula (S5)) 2.0 parts by mass Compound 3 (shown in the following formula (S6)) 0.2 parts by mass Compound 4 (shown in the following formula (S7)) 0.02 parts by mass Silica particle dispersion (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 0.1 part by mass Solvent (methylene chloride / methanol / butanol) --------------------------------

[0120] mm

[0121]

[0122]

[0123]

[0124] The dope prepared above was cast using a band film-forming machine. The dope was cast from a die onto a metal support, and then the resulting web (film) was peeled off. The drum was made of SUS.

[0125] The web (film) obtained by casting was peeled from the drum and then dried for 20 minutes in a tenter apparatus, in which both ends of the web were clipped with clips while the film was being transported at 30 to 40°C. Subsequently, the web was post-dried by zone heating while being transported with rolls. The obtained web was knurled and then wound up. The obtained cellulose acylate film had a thickness of 40 μm, an in-plane retardation of 1 nm at a wavelength of 550 nm, and a thickness direction retardation of 26 nm at a wavelength of 550 nm.

[0126] (Alkali Saponification Treatment) The cellulose acylate film obtained above was passed through a dielectric heating roll at a temperature of 60° C. to raise the film surface temperature to 40° C., and then an alkaline solution having the composition shown below was applied to the band surface of the film using a bar coater in an amount of 14 ml / m ２ The coated film was then transported for 10 seconds under a steam-type far-infrared heater manufactured by Noritake Co., Ltd. that had been heated to 110° C. Subsequently, pure water was applied at a rate of 3 ml / m using the same bar coater. ２ Next, the film was washed with water using a fountain coater and then drained with an air knife three times, and then transported to a drying zone at 70° C. for 10 seconds to dry, thereby preparing an alkali-saponified cellulose acylate film.

[0127] --------------------------------------------------- Alkaline solution ----------------------------------- Potassium hydroxide 4.7 parts by mass Water 15.8 parts by mass Isopropanol 63.7 parts by mass Surfactant: C 14 H 29 O(CHCHO) 20H 1.0 mass part Propylene glycol 14.8 mass parts

[0128] <Formation of Alignment Film> An alignment 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, and then dried with hot air at 60°C for 60 seconds and then with hot air at 100°C for 120 seconds.

[0129] Alignment film coating liquid -------------------------------- Polyvinyl alcohol (listed below) 10 parts by mass Water 371 parts by mass Methanol 119 parts by mass Glutaraldehyde (crosslinking agent) 0.5 parts by mass Citric acid ester (manufactured by Sankyo Chemical Co., Ltd.) 0.175 parts by mass ------------------------------------------------

[0130] Polyvinyl alcohol: Degree of polymerization: 300 (The value for each repeating unit represents the content (% by mass) of all repeating units.)

[0131] <Formation of First Optically Anisotropic Layer> The alignment film prepared above was continuously subjected to a 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 76°. The longitudinal direction of the film (conveying direction) was set to 90°, and when observed from the film side, the width direction of the film was used as the reference (0°) and clockwise directions were expressed as positive values, so the rotation axis of the rubbing roller was at -14°. In other words, the position of the rotation axis of the rubbing roller was rotated 76° counterclockwise from the longitudinal direction of the film.

[0132] Onto the rubbed alignment film, a composition for forming an optically anisotropic layer (1a) containing a discotic liquid crystal compound of the following composition was applied using a Giesser coater to form a composition layer. The resulting composition layer was then heated with hot air at 110°C for 2 minutes to dry the solvent and ripen the alignment of the discotic liquid crystal compound. Subsequently, the resulting composition layer was irradiated with UV light (100 mJ / cm) at 70°C. ２ ) was performed to fix the alignment of the liquid crystal compound, thereby forming an optically anisotropic layer (1a). The thickness of the optically anisotropic layer (1a) was 1.6 μm, and the in-plane retardation at 550 nm was 168 nm. Furthermore, the value obtained by dividing the in-plane retardation at a wavelength of 550 nm by the thickness of the first optically anisotropic layer was 0.105. The average tilt angle of the discotic plane of the discotic liquid crystal compound with respect to the film surface was 90°, confirming that the compound was aligned perpendicular to the film surface. Furthermore, the angle of the slow axis of the optically anisotropic layer (1a) was parallel to the rotation axis of the rubbing roller, and when the width direction of the film was 0° (the longitudinal direction was 90° counterclockwise and −90° clockwise), the slow axis was −14° when viewed from the optically anisotropic layer (1a) side. The optically anisotropic layer (1a) corresponds to the first optically anisotropic layer.

[0133] ------------------------------------------------ Composition (1a) for forming optically anisotropic layer ------------------------------------------------ 80 parts by mass of discotic liquid crystal compound 1 described below 20 parts by mass of discotic liquid crystal compound 2 described below 0.15 parts by mass of alignment film interface aligning agent 1 described below 0.1 part by mass of fluorine-containing compound A described below 0.05 part by mass of fluorine-containing compound B described below 0.21 parts by mass of fluorine-containing compound C described below 15 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 6.0 parts by mass of photopolymerization initiator (APi-307, manufactured by Shenzhen UV ChemTech Ltd.) 200 parts by mass of methyl ethyl ketone ------------------------------------------------

[0134] Discotic liquid crystal compound 1

[0135] Discotic liquid crystal compound 2

[0136] Alignment film interface alignment agent 1

[0137] Fluorine-containing compound A (in the following formula, a and b represent the content (% by mass) of each repeating unit relative to all repeating units, a represents 90% by mass and b represents 10% by mass. The weight-average molecular weight was 15,000.)

[0138] Fluorine-containing compound B (The numerical value for each repeating unit represents the content (% by mass) of all repeating units. The weight-average molecular weight was 12,500.)

[0139] Fluorine-containing compound C (the numerical value for each repeating unit represents the content (% by mass) relative to all repeating units. The weight-average molecular weight was 12,500.)

[0140] Photopolymerization initiator (APi-307, manufactured by Shenzhen UV ChemTech Ltd.)

[0141] <Formation of Second Optically Anisotropic Layer> (Formation of Optically Anisotropic Layer (B)) Onto the cellulose acylate film prepared above, an optically anisotropic layer-forming composition (1c) containing a rod-shaped liquid crystal compound having the following composition was applied using a Giesser coater to form a composition layer. Thereafter, both ends of the film were held, and a cooling plate (9°C) was placed on the side of the film on which the coating film was formed so as to be 5 mm away from the film, and a heater (75°C) was placed on the side opposite to the side on which the coating film was formed so as to be 5 mm away from the film, and the film was dried for 2 minutes. Next, the film was heated with hot air at 60°C for 1 minute, and then irradiated with a 365 nm UV-LED at an irradiation dose of 100 mJ / cm while nitrogen purging was performed to maintain an atmosphere with an oxygen concentration of 100 ppm or less. ２ The precursor layer was then irradiated with UV light (ultra-high pressure mercury lamp; UL750; manufactured by HOYA) at room temperature through a wire grid polarizer at a dose of 7.9 mJ / cm. ２ (wavelength: 313 nm) on the film, thereby forming a composition layer having alignment controllability on the surface. The film thickness of the formed composition layer was 0.6 μm. The in-plane retardation at a wavelength of 550 nm was 0 nm, and the retardation in the thickness direction at a wavelength of 550 nm was −80 nm. The average tilt angle of the long axis direction of the rod-like liquid crystal compound with respect to the film surface was 90°, and it was confirmed that the compound was aligned perpendicular to the film surface. The optically anisotropic layer (1c) corresponds to the optically anisotropic layer (B).

[0142] ------------------------------------------------ Composition for forming optically anisotropic layer (1c) -------------------------------------------------- Rod-like liquid crystal compound (A) shown below: 100 parts by mass Polymerizable monomer (A-400, manufactured by Shin-Nakamura Chemical Co., Ltd.) 4.0 parts by mass Polymerization initiator S-1 (oxime type) shown below: 5.0 parts by mass Photoacid generator D-1 shown below: 3.0 parts by mass Polymer M-1 shown below: 2.0 parts by mass Vertical alignment agent S01 shown below: 2.0 parts by mass Photoaligning polymer A-1 shown below: 42.3 parts by mass Methyl ethyl ketone 627.5 parts by mass Methyl isobutyl ketone

[0143] Rod-like liquid crystal compound (A) (hereinafter referred to as a mixture of compounds)

[0144]

[0145] Polymerization initiator S-1

[0146] Photoacid generator D-1

[0147]

[0148] Polymer M-1 (The numerical value for each repeating unit represents the content (% by mass) relative to all repeating units. The weight-average molecular weight was 58,000.)

[0149]

[0150] Vertical alignment agent S01

[0151]

[0152] Photoalignable polymer A-1 (in the following formula, a, b, and c represent the content (% by mass) of each repeating unit relative to all repeating units, with a representing 40% by mass, b representing 25% by mass, and c representing 35% by mass. The weight-average molecular weight was 69,300.)

[0153]

[0154] (Formation of Optically Anisotropic Layer (A)) Next, on the prepared optically anisotropic layer (1c) was applied a composition for forming an optically anisotropic layer (1b) containing a rod-shaped liquid crystal compound having the following composition using a Giesser coater, and the mixture was heated with hot air at 60°C for 60 seconds. Subsequently, the obtained composition layer was irradiated with UV light (300 mJ / cm) at 80°C. ２ ) was performed to fix the alignment of the liquid crystal compound, thereby forming an optically anisotropic layer (1b). The thickness of the optically anisotropic layer (1b) was 1.5 μm, Δnd at a wavelength of 550 nm was 164 nm, and the twist angle of the liquid crystal compound was 81°. When the width direction of the film was set to 0° (the longitudinal direction was 90°), the alignment axis angle of the liquid crystal compound when viewed from the optically anisotropic layer (1b) side was 14° on the air side and 95° on the side in contact with the optically anisotropic layer (1c). The alignment axis angle of the liquid crystal compound contained in the optically anisotropic layer was expressed as negative when clockwise (right-handed) and positive when counterclockwise (left-handed), with the width direction of the substrate set to 0° as the reference. The twist angle of the liquid crystal compound is expressed as a negative value when the orientation axis direction of the liquid crystal compound on the substrate side (rear side) is clockwise (right-handed) and a positive value when the orientation axis direction of the liquid crystal compound on the surface side (near side) is referenced to the orientation axis direction of the liquid crystal compound on the substrate side (rear side) when the orientation axis direction is clockwise (right-handed) and counterclockwise (left-handed) when the orientation axis direction is referenced to the orientation axis direction of the liquid crystal compound on the surface side (near side), when the orientation axis direction of the liquid crystal compound on the substrate side (rear side). The optically anisotropic layer (1b) corresponds to the optically anisotropic layer (A).

[0155] ------------------------------------------------ Composition (1b) for forming optically anisotropic layer ------------------------------------------------ Rod-shaped liquid crystal compound (A) above 70 parts by mass Rod-shaped liquid crystal compound (B) below 30 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 4 parts by mass Photopolymerization initiator (Irgacure 819, manufactured by BASF) 3 parts by mass Left-handed twisted chiral agent (L1) below 0.50 parts by mass Fluorine-containing compound D below 0.20 parts by mass Methyl isobutyl ketone 126 parts by mass Ethyl propionate 126 parts by mass

[0156] Rod-shaped liquid crystal compound (B)

[0157]

[0158] Left-handed twisted chiral dopant (L1)

[0159]

[0160] Fluorine-containing compound D (the content of the left-side repeating unit was 76 mass%, the content of the right-side repeating unit was 24 mass%, and the weight-average molecular weight was 27,500).

[0161] By the above procedure, an optically anisotropic layer (1b-1c) was prepared in which an optically anisotropic layer (1c) and an optically anisotropic layer (1b) were directly laminated on a long cellulose acylate film. When the surface of the optically anisotropic layer (1c) in contact with the optically anisotropic layer (1b) was examined, it was confirmed that a photo-alignable polymer was present. The optically anisotropic layer (1b-1c) corresponds to the optically anisotropic layer (AB).

[0162] <Preparation of Optical Film> The surface side of the optically anisotropic layer (1a) formed on the long cellulose acylate film prepared above was subjected to a corona discharge treatment. The corona discharge treatment conditions were an output intensity of 2.5 kW, a line speed of 18 m / min, an electrode length of 1.4 m, and a gap distance of 2 mm. The corona-treated surface was coated with the following ultraviolet-curable adhesive (2a) to a film thickness of 1.5 μm. The corona discharge treatment was also performed on the surface side of the optically anisotropic layer (1b) of the optically anisotropic layer (1c-1b) formed on the long cellulose acylate film prepared above. The corona discharge treatment conditions were an output intensity of 5.0 kW, a line speed of 18 m / min, an electrode length of 1.4 m, and a gap distance of 2 mm. The corona-treated surface was coated with the following adhesive (2a) to a film thickness of 1.0 μm. The adhesive (2a) coated on the optically anisotropic layer (1a) and the adhesive (2a) coated on the optically anisotropic layer (1b) were laminated together, heated to 50°C using an IR heater, and UV light was irradiated from both sides of the cellulose acylate film of the laminate to cure the adhesive (2a), followed by thermal drying at 70°C for 3 minutes. This resulted in an optical film (1a-1b-1c) having a layer structure of optically anisotropic layer (1a)-adhesive layer (2a)-optically anisotropic layer (1b-1c). In the optical film (1a-1b-1c), the optically anisotropic layer (1b) was positioned on the adhesive layer (2a) side. The in-plane retardation of the optical film (1a-1b-1c) at a wavelength of 550 nm was 141 nm.

[0163] ------------------------------------------------------------------ Adhesive (2a) ------------------------------------------------------------------ Acryloylmorpholine (manufactured by Kojinsha) 40 parts by mass N-hydroxyacrylamide (manufactured by Kojinsha) 40 parts by mass Tripropylene glycol diacrylate (Aronix M-220, manufactured by Toagosei Co., Ltd.) 20 parts by mass Photopolymerization initiator (KAYACURE DETX-S, manufactured by Nippon Kayaku Co., Ltd.) 1.5 parts by mass ------------------------------------------------------------------

[0164] <Preparation of Linear Polarizer> The support surface of a cellulose triacetate film TJ25 (manufactured by Fujifilm Corporation; thickness: 25 μm) was subjected to an alkali saponification treatment. Specifically, the support was immersed in a 1.5 N sodium hydroxide aqueous solution at 55°C for 2 minutes, then washed in a water bath at room temperature, and further neutralized with 0.1 N sulfuric acid at 30°C. After neutralization, the support was washed in a water bath at room temperature and further dried with hot air at 100°C to obtain a polarizer protective film. A roll-shaped polyvinyl alcohol (PVA) film with a thickness of 60 μm was continuously stretched in the longitudinal direction in an iodine aqueous solution and dried to obtain a linear polarizer with a thickness of 13 μm. The luminous efficiency-corrected single transmittance of the polarizer was 43%. At this time, the absorption axis direction and the longitudinal direction of the polarizer were aligned. A linear polarizer was prepared by bonding the polarizer protective film to one surface of the polarizer using the PVA adhesive described below.

[0165] (Preparation of PVA adhesive) 100 parts by mass of a polyvinyl alcohol resin having acetoacetyl groups (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, degree of acetoacetylation: 5 mol%) and 20 parts by mass of methylol melamine were dissolved in pure water at a temperature of 30°C, and the resulting aqueous solution was adjusted to a solids concentration of 3.7% by mass, thereby preparing a PVA adhesive.

[0166] <Preparation of Polarizing Plate> The exposed surface of the optical film (1a-1b-1c), which had been in contact with the cellulose acylate film of the optically anisotropic layer (1a), was subjected to a corona discharge treatment. The corona discharge treatment conditions were an output intensity of 2.5 kW, a line speed of 18 m / min, an electrode length of 1.4 m, and a gap distance of 2 mm. The corona-treated surface was coated with the adhesive (2a) described above to a film thickness of 1.5 μm. The surface of the long linear polarizer prepared above opposite the polarizer protective film and the surface of the optical film (1a-1b-1c) coated with the adhesive (2a) were bonded together, and the adhesive (2a) was cured in the same manner as described above to obtain a laminate of linear polarizer-optically anisotropic layer (1a)-adhesive layer (2a)-optically anisotropic layer (1b-1c). Subsequently, the cellulose acylate film on the optically anisotropic layer (1b-1c) side was peeled off to expose the surface of the optically anisotropic layer (1b-1c) that had been in contact with the cellulose acylate film. This produced a polarizing plate (P1) comprising the optical film (1a-1b-1c) and a linear polarizer. The polarizing plate (P1) had a polarizer protective film, a polarizer, an optically anisotropic layer (1a), an adhesive layer (2a), an optically anisotropic layer (1b), and an optically anisotropic layer (1c) laminated in this order, and corresponds to the polarizing plate of embodiment 1. The angle formed between the absorption axis of the polarizer and the slow axis of the optically anisotropic layer (1a) was −76°. Furthermore, with the width direction taken as the reference angle of 0°, the alignment axis angle of the liquid crystal compound on the optically anisotropic layer (1b) side of the optically anisotropic layer (1a) was −14°, which coincided with the slow axis direction of the optically anisotropic layer (1a).

[0167] [Examples 2 and 13-17] Polarizing plates were produced in the same manner as in Example 1, except that in the <Production of optical film> step, the component ratio of adhesive (1a) and the lamination conditions were adjusted to form an adhesive layer having the thickness and thickness unevenness σ shown in Table 1 below.

[0168] Example 3 A polarizing plate was produced in the same manner as in Example 1, except that a 5 μm-thick acrylic pressure-sensitive adhesive (NCF-D692, manufactured by Lintec Corporation) (PSA) was used instead of the adhesive (2a) used in Example 1.

[0169] Example 4 A polarizing plate was produced in the same manner as in Example 1, except that the adhesive (2a) used in Example 1 was replaced with the following adhesive (2b).

[0170] ------------------------------------------------------------------ Adhesive (2b) ------------------------------------------------------------------ CEL2021P (Daicel Chemical Industries, Ltd.) 67 parts by mass 2-Ethylhexyl glycidyl ether (Tokyo Chemical Industry Co., Ltd.) 10 parts by mass Rikaresin DME100 (New Japan Chemical Co., Ltd.) 19 parts by mass CPI-100 (San-Apro Co., Ltd.) 4 parts by mass ------------------------------------------------------------------

[0171] Examples 5 to 8 and Comparative Examples 1 to 2 Polarizing plates were prepared in the same manner as in Example 1, except that in the formation of the first optically anisotropic layer in Example 1, the amounts of ethylene oxide-modified trimethylolpropane triacrylate and photopolymerization initiator (APi-307) and the temperature during UV irradiation during the formation of the optically anisotropic layer were adjusted so that the value (Re / d) obtained by dividing the in-plane retardation of the first optically anisotropic layer at a wavelength of 550 nm by the thickness of the first optically anisotropic layer was the value shown in Table 1.

[0172] [Examples 9-10] Polarizing plates were prepared in the same manner as in Example 1, except that in the <Formation of first optically anisotropic layer> of Example 1, the film thickness of the optically anisotropic layer was adjusted to the value shown in Table 1, thereby adjusting the value (Re / d) obtained by dividing the in-plane retardation of the first optically anisotropic layer at a wavelength of 550 nm by the thickness of the first optically anisotropic layer.

[0173] [Example 11] <Formation of First Optically Anisotropic Layer> In the same manner as in the above-described optically anisotropic layer (1a), an alignment film coated on a cellulose acylate film was continuously subjected to a 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 73°. The longitudinal direction of the film (conveying direction) was set to 90°, and when observed from the film side, the width direction of the film was used as the reference (0°) and the clockwise direction was expressed as a positive value, so the rotation axis of the rubbing roller was at -17°. In other words, the position of the rotation axis of the rubbing roller was rotated 73° counterclockwise from the longitudinal direction of the film.

[0174] Onto the rubbed alignment film, a composition for forming an optically anisotropic layer (1i) containing a discotic liquid crystal compound of the following composition was applied using a Giesser coater to form a composition layer. The resulting composition layer was then heated with hot air at 110°C for 2 minutes to dry the solvent and ripen the alignment of the discotic liquid crystal compound. Subsequently, the resulting composition layer was irradiated with UV light (70 mJ / cm) at 80°C. ２ ) was performed to fix the alignment of the liquid crystal compound, thereby forming an optically anisotropic layer (1i). The thickness of the optically anisotropic layer (1i) was 2.2 μm. The in-plane retardation at 550 nm was 236 nm. The average tilt angle of the discotic plane of the discotic liquid crystal compound with respect to the film surface was 90°, and it was confirmed that the compound was aligned perpendicular to the film surface. The angle of the slow axis of the optically anisotropic layer (1i) was parallel to the rotation axis of the rubbing roller, and when the width direction of the film was 0° (the longitudinal direction was 90° counterclockwise and −90° clockwise), the angle of the slow axis was −17° when viewed from the optically anisotropic layer (1i) side. The optically anisotropic layer (1i) corresponds to the first optically anisotropic layer.

[0175] ------------------------------------------------ Optically anisotropic layer-forming composition (1i)---------------------------------------------------------------- 80 parts by mass of the above discotic liquid crystal compound 1------------------------------------------------ 20 parts by mass of the above discotic liquid crystal compound 2------------------------------------------------ 0.10 parts by mass of the above alignment film interface aligning agent 1------------------------------------------------ 0.1 part by mass of the above fluorine-containing compound A------------------------------------------------ 0.05 part by mass of the above fluorine-containing compound B------------------------------------------------ 0.21 parts by mass of the above fluorine-containing compound C------------------------------------------------ 13 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 5.0 parts by mass of photopolymerization initiator (Irgacure 907, manufactured by BASF) 200 parts by mass of methyl ethyl ketone----------------------------------------------------------------

[0176] <Formation of Second Optically Anisotropic Layer> The alignment film prepared in Example 1 was continuously subjected to a 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 105°. The longitudinal direction of the film (conveying direction) was set to 90°, and when observed from the film side, the width direction of the film was set as the reference (0°) and clockwise directions were expressed as positive values, so the rotation axis of the rubbing roller was at 75°. In other words, the position of the rotation axis of the rubbing roller was rotated 105° counterclockwise with the longitudinal direction of the film as the reference.

[0177] Onto the rubbed alignment film, a composition for forming an optically anisotropic layer (1j) containing a discotic liquid crystal compound of the following composition was applied using a Giesser coater to form a composition layer. The resulting composition layer was then heated with hot air at 60°C for 2 minutes to dry the solvent and ripen the alignment of the discotic liquid crystal compound. Subsequently, the resulting composition layer was irradiated with UV light (70 mJ / cm) at 60°C. ２) was performed to fix the alignment of the liquid crystal compound, thereby forming an optically anisotropic layer (1j). The thickness of the optically anisotropic layer (1j) was 1.1 μm. The in-plane retardation at 550 nm was 116 nm. The average tilt angle of the discotic plane of the discotic liquid crystal compound with respect to the film surface was 90°, and it was confirmed that the compound was aligned perpendicular to the film surface. The angle of the slow axis of the optically anisotropic layer (1j) was parallel to the rotation axis of the rubbing roller, and when the width direction of the film was 0° (the longitudinal direction was 90° counterclockwise and −90° clockwise), the angle of the slow axis was 75° when viewed from the optically anisotropic layer (1j) side. The optically anisotropic layer (1j) corresponds to the optically anisotropic layer (C).

[0178] ------------------------------------------------ Composition for forming optically anisotropic layer (1j)------------------------------------------------ 80 parts by mass of the above discotic liquid crystal compound 1 20 parts by mass of the above discotic liquid crystal compound 2 0.30 parts by mass of the above alignment film interface aligning agent 1 0.1 part by mass of the above fluorine-containing compound A 0.05 part by mass of the above fluorine-containing compound B 0.21 parts by mass of the above fluorine-containing compound C Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 10 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by BASF) 3.0 parts by mass Methyl ethyl ketone 200 parts by mass

[0179] <Preparation of Polarizing Plate (P11)> Using the obtained optically anisotropic layer (1i) and optically anisotropic layer (1j), an optical film (1i-1j) was obtained in the same manner as in Example 1, in which the optically anisotropic layer (1i) - adhesive layer (2a) - optically anisotropic layer (1j) were laminated in this order. Next, a polarizing plate (P11) including the optical film (1i-1j) and a linear polarizer was prepared in the same manner as in Example 1. In the polarizing plate (P11), a polarizer protective film, a polarizer, the optically anisotropic layer (1i), the adhesive layer (2a), and the optically anisotropic layer (1j) were laminated in this order, and this corresponds to the polarizing plate of Aspect 2. The angle formed by the absorption axis of the polarizer and the slow axis of the optically anisotropic layer (1i) was −73°. The angle formed by the slow axis of the optically anisotropic layer (1i) and the slow axis of the optically anisotropic layer (1j) was 58°.

[0180] [Example 12] <Formation of First Optically Anisotropic Layer> Similar to the optically anisotropic layer (1a), an alignment film coated on a cellulose acylate film was continuously subjected to a 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 75°. The longitudinal direction (conveying direction) of the film was set to 90°, and when observed from the film side, the width direction of the film was used as the reference (0°) and the clockwise direction was expressed as a positive value, so the rotation axis of the rubbing roller was at -15°. In other words, the position of the rotation axis of the rubbing roller was rotated 75° counterclockwise from the longitudinal direction of the film.

[0181] Onto the alignment film subjected to the above-mentioned rubbed treatment, a composition for forming an optically anisotropic layer (1k) containing a rod-shaped liquid crystal compound having the following composition was applied using a Giesser coater to form a composition layer. Thereafter, the obtained composition layer was heated with hot air at 110°C for 2 minutes to dry the solvent and ripen the alignment of the rod-shaped liquid crystal compound. Subsequently, the obtained composition layer was irradiated with UV light (100 mJ / cm) at 90°C. ２) was performed to fix the alignment of the liquid crystal compound, thereby forming an optically anisotropic layer (1k). The thickness of the optically anisotropic layer (1k) was 2.0 μm. The retardation at 550 nm was 220 nm. The average tilt angle of the rod-shaped liquid crystal compound with respect to the film surface was 0°, and it was confirmed that the compound was aligned horizontally with respect to the film surface. The angle of the slow axis of the optically anisotropic layer (1k) was parallel to the rotation axis of the rubbing roller, and when the width direction of the film was 0° (the longitudinal direction was 90° counterclockwise and −90° clockwise), the angle of the slow axis was −15° when viewed from the optically anisotropic layer (1k) side. The optically anisotropic layer (1k) corresponds to the first optically anisotropic layer.

[0182] Composition for forming optically anisotropic layer (1k) ---------------------------------------------------------------- Rod-shaped liquid crystal compound (A) above: 80 parts by mass Rod-shaped liquid crystal compound (B) above: 20 parts by mass Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 10 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by BASF) 3 parts by mass Fluorine-containing compound D above: 0.20 part by mass Methyl ethyl ketone 250 parts by mass

[0183] <Preparation of Polarizing Plate (P12)> Using the obtained optically anisotropic layer (1k) and the optically anisotropic layer (1j) obtained in Example 11, an optical film (1k-1j) was obtained in the same manner as in Example 1, in which the optically anisotropic layer (1k) - the adhesive layer (2a) - the optically anisotropic layer (1j) were laminated in this order. Then, a polarizing plate (P12) including the optical film (1k-1j) and a linear polarizer was prepared in the same manner as in Example 1. The polarizing plate (P12) had a polarizer protective film, a polarizer, the optically anisotropic layer (1k), the adhesive layer (2a), and the optically anisotropic layer (1j) laminated in this order, and corresponds to the polarizing plate of Aspect 2. The angle formed by the absorption axis of the polarizer and the slow axis of the optically anisotropic layer (1k) was -75°. The angle formed between the slow axis of the optically anisotropic layer (1k) and the slow axis of the optically anisotropic layer (1j) was 15°.

[0184] [Example 18] A polarizing plate was produced in the same manner as in Example 2, except that in the step of <forming a first optically anisotropic layer>, the optically anisotropic layer-forming composition (1a) was changed to the following optically anisotropic layer-forming composition (1l), and in the step of <forming a second optically anisotropic layer>, the optically anisotropic layer-forming composition (1b) was changed to the following optically anisotropic layer-forming composition (1m), and the optically anisotropic layer-forming composition (1c) was changed to the following optically anisotropic layer-forming composition (1n).

[0185] Composition for forming optically anisotropic layer (11) ---------------------------------------------------------------- Discotic liquid crystal compound 1 described above 80 parts by mass Discotic liquid crystal compound 2 described above 20 parts by mass Alignment film interface aligning agent 1 described above 1.0 part by mass Silicon-containing compound A described below 0.1 part by mass Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 13 parts by mass Photopolymerization initiator (APi-307, manufactured by Shenzhen UV ChemTech Ltd.) 6.0 parts by mass Methyl ethyl ketone 200 parts by mass

[0186] Silicon-containing compound A (in the following formula, a, b, c, and d represent the content (mol %) of each repeating unit relative to all repeating units, with a representing 78 mol %, b representing 10 mol %, c representing 1 mol %, and d representing 11 mol %. The weight-average molecular weight was 13,500.)

[0187]

[0188] ------------------------------------------------ Composition for forming optically anisotropic layer (1m)------------------------------------------------ 70 parts by mass of the above rod-shaped liquid crystal compound (A) 30 parts by mass of the above rod-shaped liquid crystal compound (B) 4 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 3 parts by mass of photopolymerization initiator (Irgacure 819, manufactured by BASF) 0.50 parts by mass of the above left-handed twisted chiral agent (L1) 0.15 parts by mass of the following silicon-containing compound B Methyl isobutyl ketone 126 parts by mass Ethyl propionate 126 parts by mass

[0189] Silicon-containing compound B (in the following formula, a, b, and c represent the content (% by mass) of each repeating unit relative to all repeating units, with a representing 56% by mass, b representing 36% by mass, and c representing 8% by mass. The weight-average molecular weight was 17,000.)

[0190]

[0191] ------------------------------------------------ Composition for forming optically anisotropic layer (1n) -------------------------------------------------- Rod-like liquid crystal compound (A) above 100 parts by mass Polymerizable monomer (A-400, manufactured by Shin-Nakamura Chemical Co., Ltd.) 4.0 parts by mass Polymerization initiator S-1 (oxime type) above 5.0 parts by mass Photoacid generator D-1 above 4.5 parts by mass Polymer M-1 above 2.0 parts by mass Vertical alignment agent S01 above 1.5 parts by mass Vertical alignment agent S02 below 0.5 parts by mass Photoaligning polymer A-2 below 1.0 part by mass Methyl ethyl ketone 42.3 parts by mass Methyl isobutyl ketone 627.5 parts by mass --------------------------------------------------

[0192] Vertical alignment agent S02

[0193]

[0194] Photoalignable polymer A-2 (in the following formula, a, b, and c represent the content (% by mass) of each repeating unit relative to all repeating units, a represents 34% by mass, b represents 26% by mass, and c represents 40% by mass. The weight-average molecular weight was 100,000.) Me represents a methyl group.

[0195]

[0196] [Example 19] A polarizing plate was produced in the same manner as in Example 18, except that the steps of <Preparation of cellulose acylate film (substrate)> and <Formation of alignment film> were changed as follows: in the step of <Formation of first optically anisotropic layer>, optically anisotropic layer-forming composition (1l) was changed to the following optically anisotropic layer-forming composition (1o); and the temperature during UV irradiation in forming the optically anisotropic layer was adjusted so that the value (Re / d) obtained by dividing the in-plane retardation of the first optically anisotropic layer at a wavelength of 550 nm by the thickness of the first optically anisotropic layer became the value shown in Table 1.

[0197] <Preparation of Cellulose Acylate Film 1 (Substrate)> (Preparation of Core Layer Cellulose Acylate Dope) The following composition was charged into a mixing tank and stirred to dissolve each component, thereby preparing a cellulose acetate solution to be used as a core layer cellulose acylate dope.

[0198] Core layer cellulose acylate dope ------------------------------------------------ Cellulose acetate having an acetyl substitution degree of 2.88: 100 parts by mass Polyester compound B described in the examples of JP-A No. 2015-227955: 8 parts by mass Compound G below: 4 parts by mass Methylene chloride (first solvent): 430 parts by mass Methanol (second solvent): 64 parts by mass

[0199] Compound G

[0200]

[0201] (Preparation of Outer Layer Cellulose Acylate Dope) 10 parts by weight of the following matting agent solution was added to 90 parts by weight of the above core layer cellulose acylate dope to prepare a cellulose acetate solution to be used as the outer layer cellulose acylate dope.

[0202] Matting agent solution - Silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass - Methylene chloride (first solvent) 76 parts by mass - Methanol (second solvent) 11 parts by mass - The above-mentioned cellulose acylate dope for the core layer 1 part by mass -

[0203] The core layer cellulose acylate dope and the outer layer cellulose acylate dope were 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. The core layer cellulose acylate dope and the outer layer cellulose acylate dope on both sides were simultaneously cast onto a drum at 20°C using a band caster from the casting nozzle. The film was peeled off while the solvent content was approximately 20% by mass, and both ends of the film in the width direction were fixed with tenter clips. The film was then dried while stretched transversely at a stretch ratio of 1.1. The resulting film was then transported between the rolls of a heat treatment device and further dried to produce an optical film with a thickness of 40 μm, designated as Cellulose Acylate Film 1. The in-plane retardation of the resulting Cellulose Acylate Film 1 at a wavelength of 550 nm was 0 nm. The resulting Cellulose Acylate Film 1 was used as a substrate.

[0204] <Formation of Alignment Film> The composition 1 for forming a photo-alignment film was continuously applied to the air side of the cellulose acylate film 1 using a Giesser coater to form a coating film. The coating film was then dried for 1 minute in a heating zone at 130°C to remove the solvent, forming a cured film with a thickness of 0.7 µm. The cured film was then irradiated with ultraviolet light (10 mJ / cm) through a wire grid polarizer. ２ , light source: ultra-high pressure mercury lamp, measurement wavelength: 313 nm), a photo-alignment film PA-1 was formed. At this time, the transmission axis of the wire grid polarizer was set at an angle of 14° with respect to the longitudinal direction of the film.

[0205] ------------------------------------------------ Photoalignment film-forming composition 1 -------------------------------------------------- Photoalignment polymer P-1 (described below) 4.0 parts by mass Epoxy compound E-1 (described below) 96.0 parts by mass Thermal acid generator B (described below) 6.0 parts by mass Diisopropylethylamine 0.6 parts by mass Butyl acetate 594.0 parts by mass Methyl ethyl ketone 306.0 parts by mass ------------------------------------------------

[0206] Photoalignment polymer P-1 (numbers assigned to each repeating unit: mass ratio of each unit to all repeating units, weight average molecular weight: 55,000)

[0207]

[0208] Epoxy compound E-1 (numbers assigned to each repeating unit: mass ratio of each unit to all repeating units, weight average molecular weight: 45,000)

[0209]

[0210] Thermal acid generator B

[0211]

[0212] ------------------------------------------------ Optically anisotropic layer forming composition (1o)---------------------------------------------------------------- 80 parts by mass of the above discotic liquid crystal compound 1------------------------------------------------ 20 parts by mass of the above discotic liquid crystal compound 2------------------------------------------------ 1.0 part by mass of the above alignment film interface aligning agent 1------------------------------------------------ 0.2 parts by mass of the above silicon-containing compound A------------------------------------------------ 5 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.)-------------------------------- 4.0 parts by mass of photopolymerization initiator (APi-307, manufactured by Shenzhen UV ChemTech Ltd.)-------------------------------- 200 parts by mass of methyl ethyl ketone----------------------------------------------------------------

[0213] [Evaluation] Organic EL display devices were fabricated using the polarizing plates of the examples and comparative examples fabricated by the above-described methods, and the following evaluations were carried out.

[0214] [Fabrication of Organic EL Display Device] A SAMSUNG GALAXY S4 equipped with an organic EL panel was disassembled, the circular polarizing plate was peeled off, and the polarizing plate fabricated above was attached to the display device using a pressure-sensitive adhesive so that the polarizer protective film was positioned on the outside.

[0215] [Evaluation of Display Performance] <Front Color Tint> The prepared organic EL display device was set to black display and observed from the front under bright light, and color tint was evaluated according to the following evaluation criteria. The results are shown in Table 2 below. A: No color tint was visible at all, or only slight color tint was visible (acceptable). B: Color tint was weakly visible, but did not pose a problem in use (acceptable). C: Color tint was visible, but did not pose a problem in use (acceptable). D: Color tint was strongly visible and not acceptable.

[0216] <Azimuth Angle Dependence of Color> The fabricated organic EL display device was set to black display, and under bright light, a fluorescent lamp was shone on it at a polar angle of 45°, and the reflected light was observed from all directions. The azimuth angle dependency of the color when viewed from an oblique direction was evaluated according to the following criteria. The results are shown in Table 2 below. A: No difference in color due to azimuth angle was visible at all. (Acceptable) B: A slight difference in color due to azimuth angle was visible, but this does not pose a problem in use. (Acceptable) C: A weak difference in color due to azimuth angle was visible, but this does not pose a problem in use. (Acceptable) D: A difference in color due to azimuth angle was visible, and it was not acceptable.

[0217] <In-Plane Color Unevenness> The prepared polarizing plate was attached to a black acrylic plate (Acrylite L502 Black, manufactured by Mitsubishi Chemical Corporation) using a pressure-sensitive adhesive, with the polarizer protective film facing outward. Under a rod-shaped fluorescent lamp (FPL-27EX-N), the polarizing plate was set at an azimuth angle, with a diffuser plate in between, such that the long axis direction of the rod-shaped fluorescent lamp and the longitudinal direction of the polarizing plate were perpendicular to each other. The in-plane color was observed from a polar angle of 30 to 40°. The in-plane color unevenness observed from an oblique angle was evaluated according to the following criteria. The results are shown in Table 2 below. A: No in-plane color unevenness was visible, or only slight (acceptable). B: Weak in-plane color unevenness was visible, but did not pose any problems in use. (Acceptable). C: In-plane color unevenness was visible, but did not pose any problems in use. (Acceptable) D: In-plane color unevenness is visible and is not acceptable.

[0218] [Air bubbles during lamination] The produced organic EL display device was set to display black and observed under bright light from the front and from a 20° angle, and defects caused by air bubbles were evaluated according to the following criteria. The results are shown in Table 2 below. No air bubbles: No defects were observed visually, and there were no problems in use. (Acceptable) Air bubbles: Clear circular discoloration marks were present, and the result was unacceptable.

[0219] [Results] The configurations and evaluation results of the polarizing plates of each Example and Comparative Example are shown in Tables 1 and 2. Table 2 is a continuation of Table 1. For example, the optical film of Example 1 has the first optically anisotropic layer and adhesive layer shown in Table 1 and the second optically anisotropic layer shown in Table 2, and has an in-plane retardation of 141 nm at a wavelength of 550 nm. In Table 1, Re / d represents the value obtained by dividing the in-plane retardation Re of the first optically anisotropic layer at a wavelength of 550 nm by the thickness d of the first optically anisotropic layer. In Tables 1 and 2, when the optically anisotropic layer consists of two layers, it is expressed as "optically anisotropic layer on the polarizer side / optically anisotropic layer on the opposite side to the polarizer side." For example, as in Example 1, when the liquid crystal type column of the second optically anisotropic layer is "rod-shaped / rod-shaped" and the liquid crystal orientation state column is "twisted / vertical," this means that the second optically anisotropic layer is formed by stacking, from the polarizer side, a layer in which twistedly oriented rod-shaped liquid crystal compounds are fixed and a layer in which vertically oriented rod-shaped liquid crystal compounds are fixed.

[0220]

[0221]

[0222] From the results shown in Tables 1 and 2, it was confirmed that when the polarizing plate of the present invention was applied to a display element to obtain a display device, and the display device was viewed from an oblique direction in black display mode, in-plane color unevenness was unlikely to occur and the azimuthal angle dependency of the color was suppressed.

[0223] Comparison of Examples 1 and 2 with Examples 13 to 17 confirmed that when the thickness unevenness σ of the adhesion layer is 35 nm or less, in-plane color unevenness is less likely to occur, and when it is less than 10 nm, in-plane color unevenness is even less likely to occur. Furthermore, comparison of Examples 1 and 2 with Examples 13 to 17 confirmed that when the thickness unevenness σ of the adhesion layer is 5 nm or more, air bubbles during lamination can be suppressed. Comparison of Examples 1 and 2 with Examples 13 to 17 confirmed that when the thickness of the adhesion layer is 10 μm or less, in-plane color unevenness can be further suppressed. Comparison of Examples 2 and 5 to 8 confirmed that when the value (Re / d) obtained by dividing the in-plane retardation Re of the first optically anisotropic layer at a wavelength of 550 nm by the thickness d of the first optically anisotropic layer is 0.110 or less, in-plane color unevenness can be further suppressed. A comparison between Example 2 and Examples 9 to 12 confirmed that when the in-plane retardation at a wavelength of 550 nm of the first optically anisotropic layer is 150 to 180 nm, the azimuthal angle dependence of the color can be further suppressed, and when it is 160 to 180 nm, the azimuthal angle dependence of the color can be further suppressed. A comparison between Example 2 and Examples 9 to 12 confirmed that when the polarizing plate of Aspect 1 is used, the color can be further suppressed when observed from the front direction.

[0224] Example 20 Formation of Optically Anisotropic Layer (1p) An optically anisotropic layer-forming composition (1p) containing a discotic liquid crystal compound having the following composition was applied to the cellulose acylate film using a Giesser coater to form a composition layer. The film on which the composition layer was formed was heated with hot air at 116°C for 1 minute, and then irradiated with a 365 nm UV-LED at a dose of 150 mJ / cm at a temperature of 78°C while purging with nitrogen to make the atmosphere have an oxygen concentration of 100 ppm by volume or less. ２ The film was then irradiated with ultraviolet light of 1000 kJ / cm 2 . The resulting coating film was then annealed with hot air at 115°C for 25 seconds to form an optically anisotropic layer (1p) (corresponding to a negative C plate). The film thickness of the formed optically anisotropic layer (1p) was 0.9 µm. The in-plane retardation Re at a wavelength of 550 nm was 0 nm, and the retardation Rth in the thickness direction at a wavelength of 550 nm was 40 nm. The average tilt angle of the discotic plane of the discotic liquid crystal compound with respect to the film plane was 0°, and it was confirmed that the compound was aligned horizontally with respect to the film plane.

[0225] Composition for forming optically anisotropic layer (1p) ---------------------------------------------------------------- 4 parts by mass of the above discotic liquid crystal compound 1 1 part by mass of the above discotic liquid crystal compound 2 95.0 parts by mass of the following discotic liquid crystal compound 3 Ethylene oxide modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 20.0 parts by mass of the above polymerization initiator S-1 (oxime type) 3.0 parts by mass of the above fluorine-containing compound B 0.6 parts by mass Methyl isobutyl ketone 361 parts by mass Ethyl propionate 90 parts by mass Methyl ethyl ketone 24 parts by mass

[0226] Discotic liquid crystal compound 3

[0227]

[0228] <Preparation of Polarizing Plate> The coated surface (exposed surface) of the optically anisotropic layer (1p) was subjected to a corona discharge treatment. The corona discharge treatment conditions were an output intensity of 2.5 kW, a line speed of 18 m / min, an electrode length of 1.4 m, and a gap distance of 2 mm. The above-described adhesive (2a) was applied to the corona-treated surface to a film thickness of 1.5 μm. The surface of a long linear polarizer prepared in the same manner as in Example 1 opposite the polarizer protective film and the surface of the optical film (1p) coated with the adhesive (2a) were bonded together, and the adhesive (2a) was cured in the same manner as described above to obtain a laminate of a linear polarizer and an optically anisotropic layer (1p). The cellulose acylate film of the optically anisotropic layer (1p) was peeled off to expose the surface of the optically anisotropic layer (1p) that had been in contact with the cellulose acylate film, and then the surface was subjected to a corona discharge treatment. The corona discharge treatment conditions were: output intensity 2.5 kW, line speed 18 m / min, electrode length 1.4 m, gap distance 2 mm. In the same manner as in Example 1, corona discharge treatment was performed on the exposed surface of the optical film (1a-1b-1c) in which the surface of the optically anisotropic layer (1a) that had been in contact with the cellulose acylate film was exposed, and then the adhesive (2a) was applied to a film thickness of 1.5 μm. The corona discharge-treated surface of the linear polarizer-optically anisotropic layer (1p) laminate prepared above and the surface of the optical film (1a-1b-1c) coated with the adhesive (2a) were bonded together, and the adhesive (2a) was cured in the same manner as described above to obtain a linear polarizer-adhesive layer (2a)-optically anisotropic layer (1p)-adhesive layer (2a)-optically anisotropic layer (1a)-adhesive layer (2a)-optically anisotropic layer (1b-1c) laminate. Subsequently, the cellulose acylate film on the optically anisotropic layer (1b-1c) side was peeled off to expose the surface of the optically anisotropic layer (1b-1c) that had been in contact with the cellulose acylate film. This produced a polarizing plate (P22) comprising the optical film (1p-1a-1b-1c) and a linear polarizer. The polarizing plate (P22) had a polarizer protective film, a polarizer, an optically anisotropic layer (1a), an adhesive layer (2a), an optically anisotropic layer (1b), and an optically anisotropic layer (1c) laminated in this order, and corresponds to the polarizing plate of Aspect 1. The in-plane retardation of the optical film (1p-1a-1b-1c) at a wavelength of 550 nm was in the range of 130 to 150 nm.The polarizing plate (P1) was evaluated in the same manner as in the polarizing plate (P1), and when the polarizing plate (P1) was applied to a display element to obtain a display device, it was confirmed that, when the display device was set to black display and viewed from an oblique direction, in-plane color unevenness was unlikely to occur and the azimuthal angle dependence of the color was suppressed. In addition, the thickness unevenness σ of the adhesion layer was 35 nm or less.

[0229] [Example 21] <Preparation of Glass with AR Layer> An inorganic oxide layer (AR layer) was formed on glass that had been subjected to chemical strengthening treatment. Specifically, the AR layer was formed by sputtering under arbitrary film-forming pressure conditions, with the layer structure being as follows: Nb ２ O ５ / SiO ２ / Nb ２ O ５ / SiO ２ The film thickness of each layer was 15 nm, 25 nm, 105 nm, and 85 nm, respectively, to produce a glass with an AR layer. The glass with the AR layer was attached to the surface of a display element to which the polarizing plate (P22) produced in Example 20 had been attached, and evaluated in the same manner as the polarizing plate (P1). When the glass was applied to the display element to obtain a display device, and the display device was set to black display and viewed from an oblique direction, it was confirmed that in-plane color unevenness was unlikely to occur and the azimuth angle dependence of the color was suppressed. In addition, the thickness unevenness σ of the adhesion layer was 35 nm or less.

[0230] Example 22 Formation of Optically Anisotropic Layer (2p) The following composition was charged into a mixing tank, stirred, and heated at 90°C for 10 minutes. The resulting composition was then filtered through a filter paper having an average pore size of 34 µm and a sintered metal filter having an average pore size of 10 µm to prepare a dope. The solid content of the dope was 23.5% by mass, and the solvent for the dope was methylene chloride / methanol / butanol = 81 / 18 / 1 (mass ratio).

[0231] -------------------------------------------------- Cellulose acylate dope -------------------------------------------------- Cellulose acylate (acetyl substitution degree 2.86, viscosity average degree of polymerization 310) 100 parts by mass Sugar ester compound 1 6.0 parts by mass Sugar ester compound 2 2.0 parts by mass Silica particle dispersion (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 0.1 part by mass Solvent (methylene chloride / methanol / butanol) --------------------------------------------------

[0232] Sugar ester compound 1

[0233]

[0234] Sugar ester compound 2

[0235]

[0236] The dope prepared above was cast using a drum film-forming machine. The dope was cast from a die onto a metal support cooled to 0°C, and then the resulting web (film) was peeled off. The drum was made of SUS.

[0237] The web (film) obtained by casting was peeled from the drum and then dried for 20 minutes in a tenter apparatus, in which both ends of the web were clipped and conveyed at 30 to 40°C during film conveyance. Subsequently, the web was post-dried by zone heating while conveying with a roll. The obtained web was knurled and then wound up. The thickness of the obtained cellulose acylate film was 40 μm, and the in-plane retardation at a wavelength of 550 nm was 1 nm and the retardation in the thickness direction at a wavelength of 550 nm was 26 nm. The cellulose acylate film thus obtained was used as an optically anisotropic layer (2p).

[0238] <Preparation of Linear Polarizing Plate> In the same manner as in Example 1, a cellulose triacetate film TJ25 (manufactured by Fujifilm Corporation: thickness 25 μm) that had been alkali saponified in the same manner as in Example 1 was bonded to one surface of a 13 μm-thick linear polarizer, and an optically anisotropic layer (2p) was bonded to the opposite surface using the above-mentioned PVA adhesive, to prepare a linear polarizing plate.

[0239] <Preparation of Polarizing Plate> A first optically anisotropic layer and a second optically anisotropic layer were prepared in the same manner as in Example 1, and were attached to the optically anisotropic layer (2p) side of the linear polarizer to prepare a polarizing plate. In this manner, a polarizing plate (P22) including optical films (1a-1b-1c) and a linear polarizer was prepared. The polarizing plate (P22) had a polarizer protective film (TJ25), a polarizer, an optically anisotropic layer (2p), an optically anisotropic layer (1a), an adhesive layer (2a), an optically anisotropic layer (1b), and an optically anisotropic layer (1c) laminated in this order, and corresponds to the polarizing plate of Aspect 1.

[0240] [Examples 23 and 24] Using the same method as in Example 22, the thickness of the optically anisotropic layer was adjusted to prepare a first optically anisotropic layer and a second optically anisotropic layer exhibiting the optical properties shown in Tables 3 and 4 below, and these layers were attached to the optically anisotropic layer (2p) side of the linear polarizer to prepare a polarizer.

[0241]

[0242]

[0243] The display elements to which the polarizing plates prepared in Examples 22 to 24 were attached were evaluated in the same manner as for the polarizing plate (P1) described above. When the polarizing plates were applied to the display elements to obtain display devices, and the display devices were viewed obliquely in black mode, it was confirmed that in-plane color unevenness was reduced and the azimuth angle dependence of the color was suppressed. In particular, in Examples 23 and 24, the reflected color from oblique directions tended to be bluish overall, resulting in little change in color when the azimuth angle was changed, giving a good impression. Furthermore, the thickness unevenness σ of the adhesion layer was 35 nm or less.

[0244] 12A, 12B First optically anisotropic layer 14A Optically anisotropic layer (A) 16A Optically anisotropic layer (B) 18B Optically anisotropic layer (C) 30A, 30B Polarizer 40A, 40B Contact layer 100A, 100B Polarizing plate

Claims

1. A polarizing plate comprising a polarizer and an optical film, wherein the optical film has an in-plane retardation of 130 to 150 nm at a wavelength of 550 nm, the optical film comprises, from the polarizer side, a first optically anisotropic layer, an adhesion layer, and a second optically anisotropic layer, wherein the first optically anisotropic layer has an in-plane retardation of 150 to 240 nm at a wavelength of 550 nm, and a value obtained by dividing the in-plane retardation of the first optically anisotropic layer at a wavelength of 550 nm by a thickness of the first optically anisotropic layer is 0.07 to 0.

116.

2. The polarizing plate according to claim 1, wherein the adhesion layer has a thickness variation of 5 to 35 nm.

3. The polarizing plate according to claim 1, wherein the in-plane retardation of the first optically anisotropic layer at a wavelength of 550 nm is 150 to 180 nm.

4. The polarizing plate according to claim 1, wherein the first optically anisotropic layer is a layer formed using a composition containing a discotic liquid crystal compound.

5. The polarizing plate according to claim 1, wherein the adhesion layer has a thickness of 0.5 to 20 μm.

6. The polarizing plate according to claim 1, wherein the adhesion layer is an adhesive layer or a pressure-sensitive adhesive layer.

7. The polarizing plate according to claim 1, wherein the optical film has an in-plane retardation of 135 to 145 nm at a wavelength of 550 nm.

8. A display device comprising a display element and the polarizing plate according to any one of claims 1 to 7.

Images