Optical laminate production method, polarizing plate production method, optical laminate, polarizing plate, and organic electroluminescent display device

Abstract

The present invention addresses the problem of providing: an optical laminate production method that can produce an optical laminate capable of inhibiting occurrence of interference color unevenness when used in an organic EL display device; the optical laminate; a polarizing plate; an antireflection film; and an organic EL display device. An optical laminate production method according to the present invention comprises a step for directly applying a liquid crystal composition, which forms an optically anisotropic layer (B) that has a phase difference that does not provide the λ / 4 function, to an optically anisotropic layer (A) that is obtained by fixing an aligned liquid crystal compound and that satisfies requirement 1 or 2 and has a phase difference that does not provide the λ / 4 function, to form a laminate having the λ / 4 function.　Requirement 1: The optically anisotropic layer (A) is surface-treated.　Requirement 2: The optically anisotropic layer (A) is formed from a liquid crystal composition containing a photoalignment polymer.

Description

Manufacturing method of optical laminate, manufacturing method of polarizing plate, optical laminate, polarizing plate, organic electroluminescence display device

[0001] The present invention relates to a method for manufacturing an optical laminate, a method for manufacturing a polarizing plate, an optical laminate, a polarizing plate, and an organic electroluminescence display device.

[0002] Circular polarizers have been used in organic electroluminescence display devices (hereinafter also referred to as "organic EL display devices") to suppress adverse effects of external light reflection. Due to the demand for thinner organic EL display devices to which circular polarizers are applied, the retardation layer included in the circular polarizer is also required to be thinner. For example, Patent Document 1 discloses an optical laminate including an optically anisotropic layer obtained by polymerizing a polymerizable liquid crystal composition as a retardation layer that achieves a thinner design.

[0003] International Publication No. 2022 / 045187

[0004] The present inventors have studied a polarizing plate having an optical laminate described in Patent Document 1 and have confirmed that when an organic EL display device using this polarizing plate is observed from an oblique direction, if thickness unevenness occurs in the adhesive layer between optically anisotropic layers, interference color unevenness is visible under a certain light source. This problem is particularly noticeable when a thin adhesive layer having a thickness of about several μm is used. The interference color unevenness is visible as interference fringe-like color unevenness having different colors (color differences) within the plane.

[0005] An object of the present invention is to provide a method for manufacturing an optical laminate that can produce an optical laminate that suppresses interference color unevenness in oblique directions when applied to an organic EL display device. Another object of the present invention is to provide a method for manufacturing a polarizing plate, an optical laminate, a polarizing plate, and an organic electroluminescence display device.

[0006] The present inventors have found that the above problems can be solved by the following configuration.

[0007] [1] A method for producing an optical laminate, comprising a step of directly applying a liquid crystal composition for forming an optically anisotropic layer (B) having a retardation that does not have a λ / 4 function to an optically anisotropic layer (A) that satisfies the following requirement 1 or 2 and is formed by fixing an aligned liquid crystal compound having a retardation that does not have a λ / 4 function, to form a laminate having a λ / 4 function. Requirement 1: The optically anisotropic layer (A) is surface-treated. Requirement 2: The optically anisotropic layer (A) is formed from a liquid crystal composition containing a photo-aligned polymer. [2] A method for producing an optical laminate according to [1], wherein the optically anisotropic layer (A) is a negative uniaxial optically anisotropic layer. [3] A method for producing an optical laminate according to [1] or [2], wherein the optically anisotropic layer (B) is an optically anisotropic layer formed by fixing a rod-like liquid crystal compound that is twisted and aligned with the thickness direction as the helical axis. [4] A method for producing the optical laminate according to any one of [1] to [3], further comprising a step of forming a C plate by directly applying a liquid crystal composition for forming a C plate onto the laminate, or a step of laminating a C plate via an adhesive layer. [5] A method for producing a polarizing plate, comprising laminating an optical laminate obtained by the method for producing an optical laminate according to any one of [1] to [4] and a polarizer to obtain a polarizing plate. [6] An optical laminate having λ / 4 function, which satisfies the following requirement 1 or 2 and comprises an optically anisotropic layer (A) having a retardation without λ / 4 function and formed by fixing an aligned liquid crystal compound, an optically anisotropic layer (B) having a retardation without λ / 4 function, an adhesive layer 2, and a C plate arranged adjacent to each other in this order. Requirement 1: The optically anisotropic layer (A) is surface-treated. Requirement 2: The optically anisotropic layer (A) is formed from a liquid crystal composition containing a photo-aligned polymer. [7] The optical laminate according to [6], wherein the adhesive layer 2 has a refractive index of 1.53 to 1.64. [8] The optical laminate according to [6] or [7], wherein silicon is present at the interface between the optically anisotropic layer (A) and the optically anisotropic layer (B).[9] A polarizing plate comprising a polarizer, an adhesive layer 1, an optically anisotropic layer (A) that satisfies the following requirement 1 or 2 and has a retardation that does not have a λ / 4 function and is formed by fixing an aligned liquid crystal compound, an optically anisotropic layer (B) that has a retardation that does not have a λ / 4 function, an adhesive layer 2, and a C-plate, arranged adjacent to each other in this order, and a laminate of the optically anisotropic layer (A) and the optically anisotropic layer (B) has a λ / 4 function. Requirement 1: The optically anisotropic layer (A) is surface-treated. Requirement 2: The optically anisotropic layer (A) is formed from a liquid crystal composition containing a photo-aligned polymer.

[10] An organic electroluminescent display device comprising the optical laminate according to any one of [6] to [8].

[11] An organic electroluminescent display device comprising the polarizing plate according to [9].

[0008] According to the present invention, there is provided a method for manufacturing an optical laminate that can produce an optical laminate in which interference color unevenness in an oblique direction is suppressed when applied to an organic EL display device. Furthermore, according to the present invention, there are provided a method for manufacturing a polarizing plate, an optical laminate, a polarizing plate, and an organic electroluminescence display device.

[0009] Fig. 1 is a schematic cross-sectional view of an 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 axes of the optically anisotropic layer (A) and the optically anisotropic layer (B) in an embodiment of the polarizing plate of the present invention. Fig. 3 is a schematic diagram showing the relationship between the angle between the absorption axis of the polarizer and the in-plane slow axes of the optically anisotropic layer (A) and the optically anisotropic layer (B) when observed from the direction of the white arrow in Fig. 1.

[0010] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, each component may be used alone or in combination with two or more substances corresponding to the component. When two or more substances are used in combination for each component, the content of the component refers to the total content of the substances used in combination, unless otherwise specified. In this specification, "(meth)acrylic" is a notation that represents "acrylic" or "methacrylic," and "(meth)acryloyl" is a notation that represents "acryloyl" or "methacryloyl." Next, the terms used in this specification will be explained.

[0011] In this specification, the slow axis is defined at 550 nm unless otherwise specified.

[0012] 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).

[0013] 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).

[0014] In this specification, "light" means actinic rays or radiation, such as 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). Of these, ultraviolet light is preferred.

[0015] In this specification, "visible light" refers to light of 380 to 780 nm. In addition, in this specification, unless otherwise specified, the measurement wavelength is 550 nm. In addition, 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.

[0016] 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 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 among the 20 slow axis orientations) is less than 10°. Vertical alignment of discotic liquid crystal compounds refers to a state in which the disc axes of the liquid crystal compounds are aligned perpendicular 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 tilt angle between the disc plane of the liquid crystal compounds in the layer and the layer surface is 70 to 110°. Furthermore, the term "same orientation" does not require that the orientation be strictly the same, but rather means that when the orientations of the slow axes are measured at any 20 positions within 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°.

[0017] In this specification, the optically anisotropic layer refers to a layer in which aligned liquid crystal compounds are fixed. The "fixed" state refers to a state in which the alignment of the liquid crystal compounds is maintained. Specifically, it is more preferable that the layer has no fluidity and can stably maintain the fixed alignment state without causing any change in the alignment state 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.

[0018] The interference color unevenness that is the problem of the present invention occurs when a polarizer, an optically anisotropic layer (A) having a retardation without a λ / 4 function, and an optically anisotropic layer (B) having a retardation without a λ / 4 function are arranged in this order. If an adhesive layer is present between the optically anisotropic layer (A) and the optically anisotropic layer (B), light incident from the polarizer side is reflected at the interface between the adhesive layer and the optically anisotropic layer and passes through the polarizer again, resulting in visible interference color unevenness. When interference color unevenness occurs, even if two or more optically anisotropic layers are made to exhibit a λ / 4 function and are arranged on an organic EL display device as a circular polarizer, a color shift occurs during black display under a certain light source. In the present invention, a manufacturing method for forming the optically anisotropic layer (B) by directly applying a liquid crystal composition for forming the optically anisotropic layer (B) onto the optically anisotropic layer (A) is used, and interference color unevenness is reduced by suppressing interfacial reflection occurring at the interface between the optically anisotropic layer (A) and the optically anisotropic layer (B).

[0019] [Optical Laminate] The optical laminate of the present invention will be described in detail below.

[0020] The optical laminate of the present invention is an optical laminate that satisfies the following requirement 1 or 2 and is produced by a method for producing an optical laminate, the method including a step of directly applying a liquid crystal composition that forms an optically anisotropic layer (B) having a retardation that does not have a λ / 4 function to an optically anisotropic layer (A) that has fixed an aligned liquid crystal compound and that has a retardation that does not have a λ / 4 function, to form a laminate having a λ / 4 function. That is, the optical laminate of the present invention is a laminate that satisfies the following requirement 1 or 2 and has a λ / 4 function, in which an optically anisotropic layer (A) that has fixed an aligned liquid crystal compound and that has a retardation that does not have a λ / 4 function and an optically anisotropic layer (B) having a retardation that does not have a λ / 4 function are arranged adjacent to each other. Requirement 1: The optically anisotropic layer (A) is surface-treated. Requirement 2: The optically anisotropic layer (A) is formed from a liquid crystal composition that contains a photo-aligned polymer. Hereinafter, the optically anisotropic layer (A) of the present invention may be referred to as the specific optically anisotropic layer (A), and the optically anisotropic layer (B) of the present invention may be referred to as the specific optically anisotropic layer (B). The λ / 4 function is specifically a function of converting linearly polarized light of a certain wavelength into circularly polarized light (or circularly polarized light into linearly polarized light).

[0021] [Optically Anisotropic Layer (A)] The optically anisotropic layer (A) of the present invention is an optically anisotropic layer having retardation without λ / 4 function, which comprises a fixed aligned liquid crystal compound and satisfies the following requirement 1 or 2. Requirement 1: The optically anisotropic layer (A) is surface-treated. Requirement 2: The optically anisotropic layer (A) is formed from a liquid crystal composition containing a photoaligned polymer.

[0022] Liquid crystal compounds can be classified into rod-shaped and discotic types based on their shape. Furthermore, each can be divided into low-molecular-weight and high-molecular-weight types. A high-molecular-weight compound generally refers to a compound with a degree of polymerization of 100 or more (see "Polymer Physics: Phase Transition Dynamics," by Masao Doi, p. 2, Iwanami Shoten, 1992). While any liquid crystal compound can be used in the present invention, rod-shaped or discotic liquid crystal compounds (discotic liquid crystal compounds) are preferred. Furthermore, monomers or relatively low-molecular-weight liquid crystal compounds with a degree of polymerization of less than 100 are preferred. Furthermore, from the perspective of fixing the alignment, the liquid crystal compound preferably has a polymerizable group. Examples of such polymerizable groups include acryloyl groups, methacryloyl groups, epoxy groups, and vinyl groups. Hereinafter, liquid crystal compounds having a polymerizable group will be referred to as "polymerizable liquid crystal compounds." The alignment of the liquid crystal compound can be fixed by polymerizing such polymerizable liquid crystal compounds. After the liquid crystal compound is fixed by polymerization, it no longer needs to exhibit liquid crystallinity.

[0023] Preferred rod-shaped liquid crystal compounds include azomethines, azoxy compounds, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles. These rod-shaped liquid crystal compounds can be fixed by introducing a polymerizable group into the terminal structure of the rod-shaped liquid crystal compound (as with the discotic liquid crystals described below) and utilizing the resulting polymerization and curing reaction. A specific example is described in JP-A No. 2006-209073, in which a polymerizable nematic rod-shaped liquid crystal compound is cured with ultraviolet light. In addition to the low-molecular-weight liquid crystal compounds described above, polymeric liquid crystal compounds can also be used. Polymeric liquid crystal compounds are polymers having side chains corresponding to the low-molecular-weight liquid crystal compounds described above. Optical compensation sheets using polymeric liquid crystal compounds are described in JP-A No. 5-53016, for example.

[0024] Examples of discotic liquid crystal compounds include benzene derivatives described in the research report by C. Destrade et al., Mol. Cryst., Vol. 71, p. 111 (1981), truxene derivatives described in the research report by C. Destrade et al., Mol. Cryst., Vol. 122, p. 141 (1985) and Physicslett, A, Vol. 78, p. 82 (1990), cyclohexane derivatives described in the research report by B. Kohne et al., Angew. Chem., Vol. 96, p. 70 (1984), and cyclohexane derivatives described in the research report by J. M. Lehn et al., J. Chem. Commun., p. 1794 (1985), and the research report by J. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994) include azacrown and phenylacetylene macrocycles.

[0025] The discotic liquid crystal compound molecules also include compounds exhibiting liquid crystallinity in which linear alkyl groups, alkoxy groups, or substituted benzoyloxy groups are radially substituted as side chains around the mother nucleus at the center of the molecule. Compounds in which the molecule or molecular aggregate has rotational symmetry and can impart a specific orientation are preferred. In optically anisotropic layers formed from compositions containing discotic liquid crystal compounds, the discotic liquid crystal compounds do not necessarily exhibit liquid crystallinity when ultimately incorporated into the optically anisotropic layer. For example, low-molecular-weight discotic liquid crystal molecules having heat- or light-reactive groups lose their liquid crystallinity when polymerized by heating or light irradiation. However, optically anisotropic layers containing such highly polymerized compounds can also be used in the present invention. Preferred examples of discotic liquid crystal compounds include those described in JP-A-8-050206. Furthermore, the polymerization of discotic liquid crystal molecules is described in JP-A-8-027284.

[0026] A method for fixing discotic liquid crystal molecules by polymerization includes a method in which a polymerizable group is bonded as a substituent to the discotic core of the discotic liquid crystal molecule, followed by polymerization. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferred, as this allows the alignment state to be maintained even during the polymerization reaction. Examples of discotic liquid crystal molecules having a polymerizable group include compounds described in paragraphs

[0151] to

[0168] of JP-A No. 2000-155216.

[0027] In the present invention, from the viewpoint of improving the color tone in the oblique direction, the optically anisotropic layer (A) is preferably a negative uniaxial optically anisotropic layer, and more preferably an optically anisotropic layer in which a vertically aligned discotic liquid crystal compound is fixed.

[0028] The in-plane retardation of the optically anisotropic layer (A) at a wavelength of 550 nm is preferably 140 to 220 nm, and more preferably 150 to 200 nm, in that black tinge is further suppressed when the organic EL display device to which the optical laminate of the present invention is applied is viewed from the front or oblique direction (hereinafter, simply referred to as "black tinge is further suppressed").

[0029] The refractive index of the optically anisotropic layer (A) is preferably from 1.50 to 1.70, more preferably from 1.55 to 1.65, from the viewpoint of increasing the refractive index anisotropy and reducing the thickness. The refractive index is measured at a wavelength of 550 nm.

[0030] In the present invention, the angle formed between the in-plane slow axis of the optically anisotropic layer (A) 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°.

[0031] When the optical laminate of the present invention is in a long shape, the angle between the longitudinal direction of the optical laminate and the in-plane slow axis of the optically anisotropic layer (A) is preferably 40 to 85°, more preferably 50 to 85°, and even more preferably 65 to 85°.

[0032] The thickness of the optically anisotropic layer (A) is preferably 0.5 μm or more, more preferably 0.8 μm or more, and even more preferably 1.0 μm or more. The thickness of the optically anisotropic layer (A) is preferably 5.0 μm or less, more preferably 4.0 μm or less, and even more preferably 3.0 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.

[0033] [Optically anisotropic layer (B)] The optically anisotropic layer (B) of the optical laminate of the present invention is a layer formed using a liquid crystal composition described later, and has an optically anisotropic layer formed by fixing an aligned liquid crystal compound. Here, the liquid crystal compound may be the same as those described for the optically anisotropic layer (A).

[0034] In the present invention, from the viewpoint of improving the reflectance in oblique directions and the color, it is more preferable that the optically anisotropic layer (B) is composed of an optically anisotropic layer in which a rod-shaped liquid crystal compound is fixed in a twisted orientation with the thickness direction as the helical axis.

[0035] As described above, the optically anisotropic layer (B) is preferably an optically anisotropic layer formed by fixing a rod-like liquid crystal compound that is twisted and aligned with the thickness direction as the helical axis, i.e., a layer formed by fixing a chiral nematic phase having a so-called helical structure. When forming the layer, it is preferable to use a liquid crystal composition obtained by mixing a liquid crystal compound that exhibits a nematic liquid crystal phase with a chiral dopant described later.

[0036] The value of the product Δnd of the refractive index anisotropy Δn of the optically anisotropic layer (B) measured at a wavelength of 550 nm and the thickness d of the optically anisotropic layer (B) is preferably 140 to 220 nm, more preferably 150 to 210 nm, and even more preferably 160 to 200 nm, in that black tinting is further suppressed. Note that the refractive index anisotropy Δn means the refractive index anisotropy of the optically anisotropic layer. The above Δnd is measured using an AxoScan (polarimeter) device from Axometrics and its device analysis software.

[0037] The twist angle of the liquid crystal compound (the twist angle of the alignment direction of the liquid crystal compound) is preferably 90±30° (within the range of 60 to 120°), more preferably 90±20° (within the range of 70 to 110°), and even more preferably 90±10° (within the range of 80 to 100°) in terms of further suppressing the appearance of black. The twist angle is measured using an Axometrics AxoScan (polarimeter) device and the company's device analysis software. Twisted alignment of the liquid crystal compound refers to the twisting of the liquid crystal compound from one main surface to the other main surface of the optically anisotropic layer (B) around the thickness direction of the optically anisotropic layer (B) as the axis. Accordingly, the alignment 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 (B).

[0038] The angle formed by the in-plane slow axis of the optically anisotropic layer (A) and the in-plane slow axis of the optically anisotropic layer (B) on the surface facing the optically anisotropic layer (A) is preferably 0 to 20°, more preferably 0 to 15°.

[0039] The thickness of the optically anisotropic layer (B) is not particularly limited, but is preferably 0.5 μm or more, more preferably 0.8 μm or more, and even more preferably 1.0 μm or more. The thickness of the optically anisotropic layer (B) is preferably 5.0 μm or less, more preferably 3.0 μm or less, and even more preferably 2.5 μm or less. 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.

[0040] (Chiral Agent) Various known chiral agents can be used as chiral agents for forming a twisted alignment of a liquid crystal compound. Chiral agents have the function of inducing a helical structure in a liquid crystal compound. Chiral compounds can be selected according to the purpose, as the sense or pitch of the helix they induce varies depending on the compound. Known compounds can be used as chiral agents, but it is preferable that they have a cinnamoyl group. Examples of the chiral agent include the 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), and JP-A Nos. 2003-287623, 2002-302487, 2002-080478, 2002-080851, 2010-181852, and 2014-034581.

[0041] Chiral agents generally contain an asymmetric carbon atom, but axially asymmetric or planarly asymmetric compounds without an asymmetric carbon atom can also be used as chiral agents. Examples of axially asymmetric or planarly asymmetric compounds include binaphthyl, helicene, paracyclophane, and derivatives thereof. The chiral agent may have a polymerizable group. When both the chiral agent and the liquid crystal compound have a polymerizable group, a polymer having a repeating unit derived from the polymerizable liquid crystal compound and a repeating unit derived from the chiral agent can be formed by polymerization of the polymerizable chiral agent and the polymerizable liquid crystal compound. In this embodiment, the polymerizable group of the polymerizable chiral agent is preferably the same type of group as the polymerizable group of the polymerizable liquid crystal compound. Therefore, the polymerizable group of the chiral agent is preferably an unsaturated polymerizable group, an epoxy group, or an aziridinyl group, more preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group. The chiral agent may also be a liquid crystal compound.

[0042] As the chiral agent, isosorbide derivatives, isomannide derivatives, binaphthyl derivatives, etc. can be preferably used. As the isosorbide derivative, a commercially available product such as LC-756 manufactured by BASF may be used. The content of the chiral agent in the liquid crystal composition is preferably 0.01 to 200 mol %, more preferably 1 to 30 mol %, of the amount of the liquid crystal compound.

[0043] [Optically Anisotropic Layer (C)] The optical laminate of the present invention preferably further comprises an optically anisotropic layer (C). The optically anisotropic layer (C) is preferably a C plate. In particular, the optically anisotropic layer (C) is a layer formed by fixing vertically aligned rod-shaped liquid crystal compounds, and is more preferably a positive C plate. The 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 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 The above "≒" encompasses not only the case where the two are completely identical, but also the case where the two are substantially identical. The term "substantially the same" includes, for example, the case where (nx-ny) x d (where d is the thickness of the film) is 0 to 10 nm, preferably 0 to 5 nm, in "nx≈ny".

[0044] The in-plane retardation of the optically anisotropic layer (C) at a wavelength of 550 nm is preferably 0 to 10 nm. The in-plane retardation is more preferably 0 to 5 nm, in order to further suppress the impartation of black color. The thickness direction retardation of the optically anisotropic layer (C) at a wavelength of 550 nm is preferably −120 to −20 nm. The thickness direction retardation is more preferably −110 to −30 nm, and more preferably −100 to −40 nm, in order to further suppress the impartation of black color.

[0045] The thickness of the optically anisotropic layer (C) is not particularly limited, but is preferably 0.2 μm or more, more preferably 0.3 μm or more, and even more preferably 0.5 μm or more. The thickness of the optically anisotropic layer (B) is preferably 4.0 μm or less, more preferably 3.0 μm or less, and even more preferably 2.0 μm or less. The thickness is determined by measuring the thickness of the optically anisotropic layer (C) at any five or more points and arithmetically averaging the measured values.

[0046] When the optical laminate of the present invention has an optically anisotropic layer (C), the order in which the layers are stacked is not particularly limited, but it is preferable that the optically anisotropic layer (A), the optically anisotropic layer (B), and the optically anisotropic layer (C) are stacked in this order.

[0047] The optical laminate of the present invention preferably has an optically anisotropic layer (A) in which a vertically aligned discotic liquid crystal compound is fixed, an optically anisotropic layer (B) in which a twisted rod-shaped liquid crystal compound with the thickness direction as the helical axis is fixed, and an optically anisotropic layer (C) in which a vertically aligned rod-shaped liquid crystal compound is fixed (hereinafter abbreviated as a "specific embodiment").

[0048] An example of a polarizing plate having the optical laminate of the specific embodiment described above will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic cross-sectional view of one embodiment of a polarizing plate 100. FIG. 2 is a diagram showing the relationship between the absorption axis of the polarizer 20 and the in-plane slow axes of the optically anisotropic layer (A) 12 and the optically anisotropic layer (B) 14 in the polarizing plate 100 shown in FIG. 1. Note that the arrow in the polarizer 20 in FIG. 2 represents the absorption axis, and the arrows in the optically anisotropic layer (A) 12 and the optically anisotropic layer (B) 14 represent the in-plane slow axes in the respective layers. FIG. 3 is a diagram showing the angular relationship between the absorption axis of the polarizer 20 (dashed line) and the in-plane slow axes (solid lines) of the optically anisotropic layer (A) 12 and the optically anisotropic layer (B) 14 when observed from the white arrows in FIG. 1. The rotation angle of the in-plane slow axis, when observed from the white arrow in Fig. 1, is expressed as a positive angle in the counterclockwise direction and a negative angle in the clockwise direction, with the absorption axis of the polarizer 20 as the reference (0°). The twist direction of the liquid crystal compound, when observed from the white arrow in Fig. 1, is determined as right-handed (clockwise) or left-handed (counterclockwise) based on the in-plane slow axis on the surface of the front side (polarizer 20 side) in the optically anisotropic layer (B) 14.

[0049] As shown in FIG. 1 , the polarizing plate 100 includes a polarizer 20, an optically anisotropic layer (A) 12, an optically anisotropic layer (B) 14, and an optically anisotropic layer (C) 16, in this order. In the optical laminate of the present invention, the optically anisotropic layer (A) 12 and the optically anisotropic layer (B) 14 are directly laminated to each other. Layers (e.g., adhesive layers) not shown may be present between the optically anisotropic layer (B) 14 and the optically anisotropic layer (C) 16, and between the polarizer 20 and the optically anisotropic layer (A). As shown in FIGS. 2 and 3 , the angle φa1 between the absorption axis of the polarizer 20 and the in-plane slow axis of the optically anisotropic layer (A) 12 is 76°. More specifically, the in-plane slow axis of the optically anisotropic layer (A) 12 is rotated by −76° (76° clockwise) with respect to the absorption axis of the polarizer 20. 2 and 3 show an embodiment in which the in-plane slow axis of the optically anisotropic layer (A) 12 is at a position of −76°, but the present invention is not limited to this embodiment, and the angle is preferably within a range of −40 to −85°, more preferably within a range of −50 to −85°, and even more preferably within a range of −65 to −85°. In other words, the angle between the absorption axis of the polarizer 20 and the in-plane slow axis of the optically anisotropic layer (A) 12 is preferably within a range of 40 to 85°, more preferably within a range of 50 to 85°, and even more preferably within a range of 65 to 85°. As shown in FIG. 2 , in the optically anisotropic layer (A) 12, the in-plane slow axis of the surface 121 of the optically anisotropic layer (A) 12 facing the polarizer 20 is parallel to the in-plane slow axis of the surface 122 of the optically anisotropic layer (A) 12 facing the optically anisotropic layer (B) 14.

[0050] 2 and 3, the in-plane slow axis of the optically anisotropic layer (A) 12 is parallel to the in-plane slow axis of the optically anisotropic layer (B) 14 at the surface 141 facing the optically anisotropic layer (A) 12. However, the present invention is not limited to this embodiment, and the angle formed by the in-plane slow axis of the optically anisotropic layer (A) 12 and the in-plane slow axis of the optically anisotropic layer (B) 14 at the surface 141 facing the optically anisotropic layer (A) 12 is preferably within the range of 0 to 20°. As described above, the optically anisotropic layer (B) 14 is an optically anisotropic layer formed by fixing rod-shaped liquid crystal compounds that are twisted and aligned with the thickness direction as the helical axis. 2 and 3, the in-plane slow axis of the optically anisotropic layer (B) 14 at the surface 141 facing the optically anisotropic layer (A) 12 and the in-plane slow axis of the optically anisotropic layer (B) 14 at the surface 142 opposite the optically anisotropic layer (A) 12 form the above-mentioned twist angle (81° in FIG. 2). That is, the angle φ2 formed by the in-plane slow axis of the optically anisotropic layer (B) 14 at the surface 141 facing the optically anisotropic layer (A) 12 and the in-plane slow axis of the optically anisotropic layer (B) 14 at the surface 142 opposite the optically anisotropic layer (A) 12 is 81°. More specifically, the twist direction of the rod-like liquid crystal compound in the optically anisotropic layer (B) 14 is left-handed (counterclockwise), and the twist angle is 81°. 2 and 3 show an embodiment in which the twist angle of the rod-shaped liquid crystal compound in the optically anisotropic layer (B) 14 is 81°, but the invention is not limited to this embodiment, and as described above, the twist angle of the rod-shaped liquid crystal compound is preferably within the range of 80±30°. That is, the angle formed by the in-plane slow axis of the surface 141 of the optically anisotropic layer (B) 14 facing the optically anisotropic layer (A) 12 and the in-plane slow axis of the surface 142 of the optically anisotropic layer (B) 14 opposite to the optically anisotropic layer (A) 12 is preferably within the range of 80±30°.

[0051] As described above, in the embodiments shown in Figures 2 and 3, when the polarizing plate 100 is observed from the polarizer 20 side, the in-plane slow axis of the optically anisotropic layer (A) 12 is rotated 81° clockwise with respect to the absorption axis of the polarizer 20, and the twist direction of the rod-shaped liquid crystal compound in the optically anisotropic layer (B) 14 is counterclockwise (left-handed twist). Although the embodiments in which the rod-shaped liquid crystal compound is twisted counterclockwise have been described in detail in Figures 2 and 3, the twist direction may be clockwise as long as a predetermined angular relationship is satisfied. More specifically, when the antireflection film 100 is observed from the polarizer 20 side, the in-plane slow axis of the optically anisotropic layer (A) 12 is rotated 81° counterclockwise with respect to the absorption axis of the polarizer 20, and the twist direction of the rod-shaped liquid crystal compound in the optically anisotropic layer (B) 14 may be clockwise (right-handed twist).

[0052] That is, in the polarizing plate 100 shown in FIG. 1 , when the antireflection film 100 is observed from the polarizer 20 side, if the in-plane slow axis of the optically anisotropic layer (A) 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 the polarizer 20, it is preferable that the twist direction of the rod-like liquid crystal compound in the optically anisotropic layer (B) is counterclockwise with respect to the in-plane slow axis of the optically anisotropic layer (B) on the surface of the optically anisotropic layer (A) side. 1 , when the polarizing plate 100 is observed from the polarizer 20 side, if the in-plane slow axis of the optically anisotropic layer (A) 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 the polarizer 20, the twist direction of the rod-shaped liquid crystal compound in the optically anisotropic layer (B) is preferably clockwise with respect to the in-plane slow axis of the surface of the optically anisotropic layer (B) facing the optically anisotropic layer (A). Even when the twist direction of the rod-shaped liquid crystal compound in the optically anisotropic layer (B) is clockwise, the angle formed by the in-plane slow axis of the optically anisotropic layer (A) and the in-plane slow axis of the surface of the optically anisotropic layer (B) facing the optically anisotropic layer (A) is preferably within a range of 0 to 20°.

[0053] [Adhesive Layer] The optical laminate of the present invention may have an adhesive layer such as a pressure-sensitive adhesive layer or an adhesive layer, for example, between the polarizer and the optically anisotropic layer (A), between the optically anisotropic layer (B) and the optically anisotropic layer (C), etc. Examples of the adhesive layer include known pressure-sensitive adhesive layers and adhesive layers.

[0054] As described in JP-A-11-149015, it is generally preferable to adjust the refractive index of the adhesive or pressure-sensitive adhesive for each layer forming a laminated wave plate or a circular polarizer in order to suppress reflection by adjusting the refractive index between layers. The difference in refractive index from the object to be adhered is preferably 0.1 or less, more preferably 0.08 or less, even more preferably 0.06 or less, and most preferably 0.03 or less. When applied to an organic EL display device, from the viewpoint of suppressing interference color unevenness in oblique directions, the refractive index of the adhesive layer is preferably 1.50 to 1.70, more preferably 1.53 to 1.64. The above refractive index is the refractive index at a wavelength of 550 nm.

[0055] When the layer is disposed between optically anisotropic layers using a liquid crystal compound, a highly refractive adhesive or pressure-sensitive adhesive may be used. To increase the refractive index, it is also preferable to use a highly refractive monomer or highly refractive metal fine particles. The highly refractive monomer preferably has a benzene ring skeleton in the molecule. Examples of monofunctional monomers having a benzene ring skeleton in the molecule include ethoxylated O-phenylphenol (meth)acrylate, O-phenylphenol glycidyl ether (meth)acrylate, para-cumylphenoxyethylene glycol (meth)acrylate, 2-methacryloyloxyethyl phthalate, 2-acryloyloxyethyl phthalate, 2-acryloyloxyethyl-2-hydroxyethyl phthalate, 2-acryloyloxypropyl phthalate, phenoxyethyl (meth)acrylate, EO-modified phenol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, EO-modified nonylphenol (meth)acrylate, PO-modified nonylphenol (meth)acrylate, phenyl glycidyl ether (meth)acrylate, neopentyl glycol benzoate (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, ECH-modified phenoxy (meth)acrylate, benzyl (meth)acrylate, and vinyl carbazole. Components constituting inorganic particles include metal oxides, metal nitrides, metal oxynitrides, and elemental metals. Metal atoms contained in the metal oxides, metal nitrides, metal oxynitrides, and elemental metals include titanium atoms, silicon atoms, aluminum atoms, cobalt atoms, and zirconium atoms. Specific examples of inorganic particles include inorganic oxide particles such as alumina particles, alumina hydrate particles, silica particles, zirconia particles, and clay minerals (e.g., smectite). From the perspective of refractive index, zirconium oxide fine particles are preferred. The refractive index can be adjusted to a predetermined value by varying the amount of inorganic fine particles. When zirconium oxide is used as the main component, the average particle size of the inorganic fine particles in the layer is preferably 1 to 120 nm, more preferably 1 to 60 nm, and even more preferably 2 to 40 nm.

[0056] The thickness of the adhesive layer is not particularly limited, but is preferably 0.5 μm or more, more preferably 0.8 μm or more. The thickness of the adhesive layer is often 50 μm or less, preferably 20 μm or less, more preferably 5 μm or less. The thickness is determined by observing the cross section of the adhesive layer with a scanning electron microscope (SEM).

[0057] In particular, the optical laminate of the present invention preferably has the optically anisotropic layer (A), the optically anisotropic layer (B), the adhesive layer 2, and the C plate arranged adjacent to each other in this order, or the optically anisotropic layer (A), the optically anisotropic layer (B), and the C plate arranged adjacent to each other in this order, and more preferably has the optically anisotropic layer (A), the optically anisotropic layer (B), the adhesive layer 2, and the C plate arranged adjacent to each other in this order. The adhesive layer 2 is a layer that bonds the optically anisotropic layer (B) and the C plate, and specific examples and preferred aspects are the same as those of the adhesive layer described above.

[0058] In the optical laminate of the present invention, silicon is preferably present at the interface between the optically anisotropic layer (A) and the optically anisotropic layer (B). The presence of silicon at the interface specifically refers to the presence of silicon on at least one of the surface of the optically anisotropic layer (A) facing the optically anisotropic layer (B) and the surface of the optically anisotropic layer (B) facing the optically anisotropic layer (A). It is preferable that silicon be present at least on the surface of the optically anisotropic layer (A) facing the optically anisotropic layer (B). The form of silicon is not particularly limited, and examples thereof include a portion of the components in each optically anisotropic layer (e.g., the surfactants described below), and decomposition products or reaction products thereof. The presence of silicon at the interface can be confirmed, for example, by measuring the exposed interface using X-ray photoelectron spectroscopy. A method for having silicon present at the interface includes, for example, forming the optically anisotropic layer (A) using a liquid crystal composition containing a component containing a silicon atom.

[0059] The thickness of the optical laminate of the present invention is not particularly limited, but is preferably 2.0 μm or more, more preferably 3.0 μm or more, and even more preferably 3.5 μm or more. The thickness of the optical laminate is often 15.0 μm or less, preferably 10.0 μm or less, and more preferably 5.0 μm or less. The thickness is determined by observing the cross section of the laminate using an SEM.

[0060] [Method for Producing an Optical Laminate] The method for producing an optical laminate of the present invention will be described in detail. The method for producing an optical laminate of the present invention includes a step of forming a laminate having λ / 4 function by directly coating a liquid crystal composition for forming an optically anisotropic layer (B) having a retardation that does not have λ / 4 function onto an optically anisotropic layer (A) that satisfies the following requirement 1 or 2 and is formed by fixing an aligned liquid crystal compound having a retardation that does not have λ / 4 function. Requirement 1: The optically anisotropic layer (A) is surface-treated. Requirement 2: The optically anisotropic layer (A) is formed from a liquid crystal composition containing a photo-aligned polymer. Specific procedures are described below. First, a liquid crystal composition is coated on a support (preferably a long support) to form the optically anisotropic layer (A). Here, the optically anisotropic layer (A) needs to be endowed with the function of aligning the optically anisotropic layer (B) to be formed thereon. Examples of means for imparting alignment function to the optically anisotropic layer (A) include a method of performing a surface treatment after forming the optically anisotropic layer (A) (Requirement 1: the optically anisotropic layer (A) has been surface-treated), and a method of imparting alignment function to the optically anisotropic layer (A) by incorporating a photo-alignment polymer into the liquid crystal composition forming the optically anisotropic layer (A) and then curing the resulting optically anisotropic layer (A) (Requirement 2: the optically anisotropic layer (A) is formed from a liquid crystal composition containing a photo-alignment polymer). Next, a liquid crystal composition for forming the optically anisotropic layer (B) is directly applied onto the resulting optically anisotropic layer (A) to form the optically anisotropic layer (B), thereby obtaining a laminate. When the optical laminate of the present invention satisfies Requirement 1, the liquid crystal composition for forming the optically anisotropic layer (B) is preferably applied onto the surface of the optically anisotropic layer (A) that has been surface-treated. When Requirement 2 is satisfied, the liquid crystal composition for forming the optically anisotropic layer (B) is preferably applied onto the surface where the photo-alignment polymer of the optically anisotropic layer (A) is present (preferably, onto the surface where the photo-alignment polymer is unevenly distributed). The optical properties of the optically anisotropic layer (A) and the optically anisotropic layer (B) may be adjusted appropriately so that the optical laminate including the optically anisotropic layer (A) and the optically anisotropic layer (B) has a λ / 4 function.The method for producing the optical laminate of the present invention may further include a step of separately applying a liquid crystal composition (preferably a liquid crystal composition that forms a C plate) onto a substrate to form an optically anisotropic layer (C) (preferably a C plate) via an adhesive layer, or may include a method of imparting an alignment function to the optically anisotropic layer (B) by a method similar to the above-mentioned method, and then applying a liquid crystal composition (preferably a liquid crystal composition that forms a C plate) directly onto the optically anisotropic layer (B) to form the optically anisotropic layer (C) (preferably a C plate).

[0061] It is preferred that the specific optically anisotropic layer (A) is a negative uniaxial optically anisotropic layer, and the specific optically anisotropic layer (B) is an optically anisotropic layer formed by fixing a rod-shaped liquid crystal compound that is twisted and aligned with the thickness direction as the helical axis. The reverse configuration is also possible, i.e., the specific optically anisotropic layer (A) is an optically anisotropic layer formed by fixing a rod-shaped liquid crystal compound that is twisted and aligned with the thickness direction as the helical axis, and the specific optically anisotropic layer (B) is a negative uniaxial optically anisotropic layer. In the case of such an optical laminate, it is preferred to manufacture a polarizing plate, as described below, by disposing the optically anisotropic layer (C) (preferably a C plate) on the optically anisotropic layer (A) side and the polarizer on the optically anisotropic layer (B) side. The substrate and liquid crystal composition, as well as a method for forming an optically anisotropic layer using the liquid crystal composition, are described in detail below.

[0062] <Substrate> The substrate is preferably a transparent substrate. The transparent substrate is intended to mean a substrate having a visible light transmittance of 60% or more, preferably 80% or more, and more preferably 90% or more.

[0063] The retardation value (Rth(550)) in the thickness direction of the substrate at a wavelength of 550 nm is not particularly limited, but is preferably −110 to 110 nm, more preferably −80 to 80 nm. The in-plane retardation value (Re(550)) of the substrate at a wavelength of 550 nm is not particularly limited, but is preferably 0 to 50 nm, more preferably 0 to 30 nm, and even more preferably 0 to 10 nm.

[0064] As the material for forming the substrate, a polymer excellent in optical performance transparency, mechanical strength, thermal stability, moisture blocking property, isotropy, etc. is preferred. Examples of polymer films that can be used as the substrate include cellulose acylate films (e.g., cellulose triacetate film (refractive index 1.48), cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film), polyolefin films such as polyethylene and polypropylene, polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films, polyacrylic films such as polymethyl methacrylate, polyurethane films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyether ketone films, (meth)acrylonitrile films, and films of polymers having an alicyclic structure (norbornene-based resins (Arton: trade name, manufactured by JSR Corporation, amorphous polyolefins (Zeonex: trade name, manufactured by Nippon Zeon Co., Ltd.))). Among these, triacetyl cellulose, polyethylene terephthalate, or a polymer having an alicyclic structure is preferred as the material for the polymer film, and triacetyl cellulose is more preferred.

[0065] The substrate may contain various additives (for example, an optical anisotropy adjusting agent, a wavelength dispersion adjusting agent, fine particles, a plasticizer, an ultraviolet light inhibitor, a deterioration inhibitor, a release agent, etc.).

[0066] 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. The substrate may also be composed of a laminate of multiple sheets. To improve adhesion with a layer disposed thereon, 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). An adhesive layer (undercoat layer) may also be provided on the substrate. A polymer layer containing 5 to 40% by mass of inorganic particles with an average particle size of approximately 10 to 100 nm in solid content may be disposed on one side of the substrate to impart slipperiness during the transport process or to prevent sticking between the front and back surfaces after winding.

[0067] The substrate may be a so-called temporary support, that is, after producing the optical layered body of the present invention, the substrate may be peeled off from the optically anisotropic layer.

[0068] Alternatively, the surface of the substrate may be directly subjected to rubbing treatment. In other words, a rubbed substrate may be used. The direction of the rubbing treatment is not particularly limited, and an optimal direction may be appropriately selected depending on the desired direction of alignment of the liquid crystal compound. The rubbing treatment may be a treatment method that is widely used as a liquid crystal alignment treatment step for LCDs (liquid crystal displays). In other words, 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.

[0069] An alignment film may be disposed on the substrate. The alignment film can be formed by means of rubbing an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer with microgrooves, or deposition of an organic compound (e.g., ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearate) using the Langmuir-Blodgett method (LB film). Furthermore, alignment films that exhibit alignment function upon application of an electric field, a magnetic field, or light irradiation (preferably polarized light) are also known. Examples of alignment films include photoalignment films. The thickness of the alignment film is not particularly limited as long as it can exhibit 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. The alignment film may be peelable from the optically anisotropic layer together with the substrate.

[0070] <Liquid Crystal Composition> The liquid crystal compound contained in the liquid crystal composition that forms the optically anisotropic layer is as 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. The content of the liquid crystal compound in the liquid crystal composition is preferably 60 to 99% by mass, more preferably 70 to 98% by mass, based on the total solid content of the liquid crystal composition. The solid content refers to components that can form the optically anisotropic layer after removing the solvent, and is considered to be solid content even if the component is in a liquid state.

[0071] The liquid crystal composition may contain compounds other than liquid crystal compounds. For example, the liquid crystal composition for forming the optically anisotropic layer (A) described above may contain a photoalignable polymer. Note that a liquid crystal composition for forming an optically anisotropic layer other than the optically anisotropic layer (A) (e.g., the optically anisotropic layer (B)) may contain a photoalignable polymer. The photoalignable polymer is preferably a polymer having a photoalignable group and a localized group. The main chain of the polymer is not particularly limited, and examples thereof include known structures. For example, a skeleton selected from the group consisting of (meth)acrylic, styrene, siloxane, cycloolefin, methylpentene, amide, and aromatic ester is preferred. Of these, a skeleton selected from the group consisting of (meth)acrylic, siloxane, and cycloolefin is more preferred, and a (meth)acrylic skeleton is even more preferred. Note that (meth)acrylic is a general term for acrylic and methacrylic. Suitable examples of the photoalignment group include a group having a skeleton of at least one derivative selected from the group consisting of cinnamic acid derivatives, coumarin derivatives, chalcone derivatives, maleimide derivatives, and benzophenone derivatives, or a group having a skeleton of at least one compound selected from the group consisting of azobenzene compounds, stilbene compounds, spiropyran compounds, cinnamic acid compounds, and hydrazono-β-ketoester compounds. Among these photoalignment groups, a group selected from the group consisting of cinnamoyl groups, azobenzene groups, chalconyl groups, and coumarin groups is preferred, with cinnamoyl groups being more preferred, because this improves the liquid crystal alignment of the optically anisotropic layer formed on the upper layer even with a low exposure dose. The unevenly distributed group preferably has a substituent containing a fluorine atom or a silicon atom. Using such a photoalignment polymer makes it easier for the photoalignment polymer to unevenly distribute on the surface of the optically anisotropic layer (A), thereby enabling more efficient direct alignment of the optically anisotropic layer (B) formed on the optically anisotropic layer (A).Known examples of such photo-aligned polymers include copolymers having a repeating unit containing a photo-aligned group, as in WO 2018 / 216812, and a repeating unit having a unidirectional group at the end and containing a group as a linking group that is cleaved by the action of at least one selected from the group consisting of light, heat, acid, and base, and photo-aligned polymers having a photo-aligned group and a unidirectional group, as described in WO 2022 / 071410 (particularly copolymers containing a repeating unit containing a photo-aligned group and a repeating unit containing a unidirectional group).

[0072] The liquid crystal composition for forming an optically anisotropic layer, which is formed by fixing rod-shaped liquid crystal compounds that are twisted and aligned with the helical axis in the thickness direction, preferably contains a chiral dopant in order to twist the liquid crystal compounds. Details of the chiral dopant are as described above.

[0073] The liquid crystal composition 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 liquid crystal composition is preferably 0.01 to 20% by mass, more preferably 0.5 to 10% by mass, based on the total solid content of the liquid crystal composition.

[0074] In addition to the above, other components that may be contained in the liquid crystal composition include a polyfunctional monomer, an alignment control agent (vertical alignment agent, horizontal alignment agent), a surfactant, an adhesion improver, a plasticizer, a photoacid generator, and a solvent.

[0075] The surfactant preferably has a so-called leveling function that flattens the applied film. For example, silicon atom-containing compounds, polyacrylate compounds, and fluorine atom-containing compounds can be used. Specifically, the surfactant can be used with reference to the compounds and amounts added described in paragraphs

[0032] to

[0036] of JP 2020-098349 A, paragraphs

[0032] to

[0039] of WO 2020 / 149357 A, and WO 2023 / 054164 A. In particular, from the viewpoint of reducing environmental pollution, the surfactant is preferably a silicon atom-containing compound or a polyacrylate compound, and more preferably a compound having a branched siloxane structure. Among these, copolymers (surfactants) described in Table 1 of WO 2023 / 054164 are preferred. The content of the surfactant is preferably 0.01% to 10%, more preferably 0.01% to 6.0%, and even more preferably 0.05% to 3.0%, relative to the total mass of the solid content of the liquid crystal composition. Similarly, from the viewpoint of reducing environmental pollution, it is preferable that the fluorine atom content of the surfactant is low, and is preferably 10% or less, more preferably 5% or less, and even more preferably 3% or less, calculated on a weight basis in the compound. 0% is the most preferable lower limit, but a small amount (for example, 0.01 to 1.0%) may be contained as long as it has little effect on environmental pollution. When a silicon atom-containing compound is used as the surfactant, silicon is present at the interface between the optically anisotropic layer (A) and the optically anisotropic layer (B).

[0076] <Method of forming optically anisotropic layer> The procedure for forming the optically anisotropic layer is not particularly limited, and examples thereof include a method of applying the above-mentioned liquid crystal composition to a substrate and, if necessary, performing a drying treatment (hereinafter, also simply referred to as a "coating method"). Note that the optically anisotropic layer may be formed by applying the liquid crystal composition to another layer formed on a substrate other than the above-mentioned substrate. For example, the optically anisotropic layer may be formed by directly applying the liquid crystal composition to an optically anisotropic layer formed on a substrate.

[0077] The coating method is not particularly limited, and examples thereof include wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. If necessary, after coating the composition, a treatment for drying the coating film coated on the substrate may be carried out. By carrying out the drying treatment, the solvent can be removed from the coating film.

[0078] 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.

[0079] Next, the formed coating film is subjected to an alignment treatment to align the liquid crystal compound in the coating film. The alignment treatment can be performed 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 changes in temperature or pressure. In the case of a lyotropic liquid crystal compound, the transition can also be achieved by changing 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.

[0080] Next, it is preferable to perform a curing treatment on the coating film in which the liquid crystal compound has been aligned. The method of curing the coating film in which the liquid crystal compound has been aligned is not particularly limited, and examples thereof include light irradiation treatment and heat treatment. Among these, from the viewpoint of manufacturability, light irradiation treatment is preferred, and ultraviolet irradiation treatment is more preferred. The irradiation conditions for the light irradiation treatment 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.

[0081] Furthermore, when the liquid crystal composition contains a photoalignable polymer, it is preferable to perform a photoalignment treatment when forming the optically anisotropic layer in order to impart alignment function. Examples of the photoalignment treatment include a method of irradiating a coating film of the liquid crystal composition (including a cured film that has been cured) with polarized light or non-polarized light from an oblique direction to the coating film surface. The timing of performing the photoalignment treatment is not particularly limited, but it is more preferable to perform it after the alignment treatment of the liquid crystal compound.

[0082] In the photo-alignment treatment, the polarized light to be irradiated is not particularly limited, and examples thereof include linearly polarized light, circularly polarized light, and elliptically polarized light, with linearly polarized light being preferred. The "oblique direction" in which unpolarized light is irradiated is not particularly limited as long as it is a direction tilted at a polar angle θ (0<θ<90°) with respect to the normal direction of the coating film surface, and can be appropriately selected depending on the purpose, with θ being preferably 20 to 80°.

[0083] 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 such light sources can be limited by using an interference filter or color filter. Furthermore, linearly polarized light can be obtained by using a polarizing filter or polarizing prism on the light from these light sources.

[0084] 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.

[0085] Furthermore, when the optically anisotropic layer (e.g., optically anisotropic layer (A)) serving as the substrate is formed from a liquid crystal composition that does not contain a photoalignable polymer, it is preferable to perform a surface treatment on the optically anisotropic layer serving as the substrate, and then coat and laminate the liquid crystal composition that forms the optically anisotropic layer to be laminated (e.g., optically anisotropic layer (B)). By performing the surface treatment, the coatability (e.g., coating repelling) of the liquid crystal composition onto the optically anisotropic layer serving as the substrate is improved, and the liquid crystal compound in the coated liquid crystal composition is more likely to be aligned along the alignment state on the surface of the optically anisotropic layer serving as the substrate. Examples of surface treatments include glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, and flame treatment, with corona discharge treatment being preferred.

[0086] Regarding the corona discharge treatment, if the corona treatment amount is small, the orientation of the laminated optically anisotropic layer will be insufficient, and if the treatment amount is large, the manufacturing process may be contaminated. The corona treatment amount is 10 to 200 W·min / m ２ is preferable, and 20 to 100 W·min / m ２ is more preferred.

[0087] [Polarizing Plate] The polarizing plate and the organic EL display device of the present invention will be described in detail below.

[0088] The polarizing plate of the present invention includes a polarizer and the optical laminate of the present invention. The polarizing plate can be used as a circular polarizing plate. Note that a circular polarizing plate is an optical element that converts unpolarized light into circularly polarized light.

[0089] [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, such as an absorption polarizer. The type of polarizer is not particularly limited, and commonly used polarizers can 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 then stretching the resulting mixture. A protective film may be disposed on one or both sides of the polarizer.

[0090] 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 (e.g., 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.

[0091] 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 μm 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 parts. Of course, it is also possible to peel off the support and transfer the polarizer for use.

[0092] From the viewpoint of power saving, the luminous-corrected single transmittance of the polarizer is preferably 40% or more, more preferably 44% or more, and even more preferably 50% or more. The upper limit is not particularly limited, but is preferably 60% or less. In the present invention, the luminous-corrected single transmittance of the polarizer is measured using an automatic polarizing film measuring device: VAP-7070 (manufactured by JASCO Corporation). The luminous-corrected single transmittance can be measured as follows. A sample (5 cm x 5 cm) is prepared by attaching a polarizer to glass via an adhesive. At this time, a polarizing plate protective film is attached to the polarizer so that it is on the side opposite the glass (air interface). The glass side of this sample is set facing the light source, and measurement is performed. The configuration of the polarizer protective film is not particularly limited, and may be, for example, a support or a coating layer, or a laminate of a support and a coating layer. The coating layer may be a known layer, such as a polymer or a layer obtained by polymerizing and curing a polyfunctional monomer. Examples of the polymer include a (meth)acrylic polymer and a cycloolefin polymer. The polymerizable monomer may be a radically polymerizable or cationically polymerizable compound. The bonding surface between the polarizer and the protective film is not particularly limited, and for example, the coating layer side of the support and the coating layer may be bonded to the polarizer for the purpose of suppressing diffusion of potassium ions or iodine ions from the polarizer over time under moist heat.

[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 preparing a polarizer and an optical laminate and bonding them in a predetermined direction via an adhesive layer. Examples of the adhesive layer include the adhesive layer described above. A polarizing plate manufactured by this method preferably has a polarizer, adhesive layer 1, specific optically anisotropic layer (A), specific optically anisotropic layer (B), adhesive layer 2, and a C plate arranged adjacent to each other in this order. Adhesive layer 1 is a layer that bonds the polarizer and the optically anisotropic layer (A), and specific examples and preferred embodiments are the same as those of the adhesive layer that may be included in the optically anisotropic layer described above. Here, adhesive layer 2 and a C plate may or may not be included, but the presence of a C plate is preferred from the perspective of optical properties. The C plate can be arranged adjacent to the specific optically anisotropic layer (B) using the method described above, i.e., it is also possible to configure a structure in which adhesive layer 2 is not included and the C plate is directly adjacent to the specific optically anisotropic layer (B). Alternatively, a polarizing plate in which a polarizer and an optical laminate are directly laminated may be produced by using a coating-type polarizer and directly coating the polarizer on an optical laminate. The polarizing plate produced by this method preferably has a polarizer, a specific optically anisotropic layer (A), a specific optically anisotropic layer (B), an adhesive layer 2, and a C plate arranged adjacent to each other in this order. While the adhesive layer 2 and the C plate do not have to be included, the presence of the C plate is preferable from the viewpoint of optical properties. The C plate can be arranged adjacent to the specific optically anisotropic layer (B) by the above-mentioned method, i.e., the adhesive layer 2 is not included, and the C plate can be directly adjacent to the specific optically anisotropic layer (B).

[0094] [Organic EL display device] The organic EL display device of the present invention has the above-mentioned optical laminate or polarizing plate. Usually, the optical laminate or polarizing plate is provided on an organic EL display panel of the organic EL display device. That is, the organic EL display device of the present invention has an organic EL display panel and the above-mentioned optical laminate or polarizing plate.

[0095] An organic EL display panel is a component 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, a protective layer, etc. 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.

[0096] The features of the present invention will be explained in more detail below with reference to examples and comparative 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 specific examples shown below.

[0097] Example 1 (Preparation of Cellulose Acylate Film (Substrate)) The following composition was charged into a mixing tank, stirred, and further heated at 90°C for 10 minutes. The obtained composition was then filtered through filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm to prepare a dope. The solid content concentration of the dope was 23.5 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).

[0098] ------------------------------------------------ Cellulose acylate dope ------------------------------------------------ Cellulose acylate (acetyl substitution degree 2.86, viscosity average polymerization degree 310) 100 parts by mass Sugar ester compound 1 (shown in chemical formula (S4)) 6.0 parts by mass Sugar ester compound 2 (shown in chemical formula (S5)) 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) ------------------------------------------------

[0099]

[0100]

[0101] 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 from the drum. The drum was made of SUS.

[0102] The web (film) obtained by casting was peeled from the drum and then dried for 20 minutes in a tenter apparatus, which clipped both ends of the web with clips while transporting the film at 30 to 40°C. Subsequently, the web was post-dried by zone heating while being transported with a roll. The obtained web was knurled and then wound up. The thickness of the obtained cellulose acylate film was 40 μm, the in-plane retardation Re(550) at a wavelength of 550 nm was 1 nm, and the retardation in the thickness direction Rth(550) at a wavelength of 550 nm was 26 nm.

[0103] (Alkaline Saponification Treatment) The above-mentioned cellulose acylate film 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.

[0104] 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 (CH ２ CH ２ O) ２０ H 1.0 mass part Propylene glycol 14.8 mass parts

[0105] (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.

[0106] ------------------------------------------------------------------ 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 ------------------------------------------------------------------

[0107] (Polyvinyl alcohol)

[0108]

[0109] (Formation of Optically Anisotropic Layer (A)) 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 transport direction, and the angle between the longitudinal direction of the film (transport direction) and the rotation axis of the rubbing roller was 76°. Assuming that the longitudinal direction of the film (transport direction) is 90° and that the clockwise direction is expressed as a positive value with the film width direction as the reference (0°) when observed from the film side, the rotation axis of the rubbing roller was at -14°. In other words, the position of the rotation axis of the rubbing roller was a position rotated 76° clockwise with the longitudinal direction of the film as the reference when observed from the film side.

[0110] 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 80°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 1.1 μm. The in-plane retardation at a wavelength of 550 nm was 168 nm. 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. The angle of the in-plane 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 in-plane slow axis was −14° when viewed from the optically anisotropic layer (1a) side. The optically anisotropic layer (1a) corresponds to the optically anisotropic layer (A) having a retardation without λ / 4 function.

[0111] 0.21 parts by mass of fluorine-containing compound C below 10 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) 3.0 parts by mass Methyl ethyl ketone 200 parts by mass

[0112] Discotic liquid crystal compound 1

[0113]

[0114] Discotic liquid crystal compound 2

[0115]

[0116] Alignment film interface alignment agent 1

[0117]

[0118] Fluorine-containing compound A

[0119]

[0120] The above a and b represent the content (% by mass) of each repeating unit relative to all repeating units, with a representing 90% by mass and b representing 10% by mass.

[0121] Fluorine-containing compound B (the numerical value for each repeating unit represents the content (% by mass) relative to all repeating units, the content of the repeating unit on the left side was 32.5% by mass, and the content of the repeating unit on the right side was 67.5% by mass.)

[0122]

[0123] Fluorine-containing compound C (the numerical value for each repeating unit represents the content (% by mass) relative to all repeating units, and the content of the repeating unit on the left side was 25% by mass, the content of the repeating unit in the middle was 25% by mass, and the content of the repeating unit on the right side was 50% by mass).

[0124]

[0125] (Formation of Laminate of Optically Anisotropic Layer (A) and Optically Anisotropic Layer (B)) (Formation of Optically Anisotropic Layer (1b)) The surface of the optically anisotropic layer (1a) of the optically anisotropic layer (A) prepared above was heated at 50 W·min / m 2 The corona-treated surface was then coated with a composition (1b) for forming an optically anisotropic layer containing a rod-shaped liquid crystal compound having the following composition using a Giesser coater, and heated with hot air at 80°C for 60 seconds. Subsequently, the resulting composition layer was irradiated with UV light (500 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 1.2 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 85° on the air side and -14° on the side in contact with the optically anisotropic layer (1a). 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 taken as a reference when observing the substrate from the surface side of the optically anisotropic layer. The optically anisotropic layer (1b) corresponds to the optically anisotropic layer (B) having a retardation without λ / 4 function.

[0126] Composition for forming optically anisotropic layer (1b) ------------------------------------------------ Rod-like liquid crystal compound L-1 below: 100 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: 0.60 parts by mass Fluorine-containing compound C above: 0.08 parts by mass Methyl ethyl ketone 156 parts by mass

[0127] Rod-shaped liquid crystal compound L-1

[0128]

[0129] Left-twisted chiral agent (L1)

[0130]

[0131] By the above procedure, a laminate (1a-1b) was prepared in which an optically anisotropic layer (1a) and an optically anisotropic layer (1b) were directly laminated on a continuous cellulose acylate film. The laminate (1a-1b) corresponds to a laminate having a λ / 4 function.

[0132] (Preparation of Optically Anisotropic Layer (C))

[0133] The following composition 1c for forming an optically anisotropic layer was applied to the support prepared in Example 1 using a Giesser coater to form a composition layer. The first temporary support on which the composition layer was formed was heated with hot air at 60°C for 1 minute, and then irradiated with ultraviolet light (irradiation dose 120 mJ / cm) while purging with nitrogen so that the atmosphere had an oxygen concentration of 100 ppm by volume or less. ２, using an ultra-high pressure mercury lamp) was performed to fix the alignment of the rod-shaped liquid crystal compound L-1, thereby forming an optically anisotropic layer (1c). The film thickness of the optically anisotropic layer (1c) was 0.7 μm. The Re(550) of the optically anisotropic layer (1c) was 0 nm and Rth(550) was −80 nm. The average tilt angle of the rod-shaped liquid crystal compound L-1 with respect to the surface of the optically anisotropic layer was 90°, and the compound was aligned perpendicular to the surface of the support.

[0134] ------------------------------------------------ Optically anisotropic layer forming composition (1c)------------------------------------------------ Rod-like liquid crystal compound L-1 described above 100 parts by mass Polyfunctional monomer (UA-306I, manufactured by Kyoeisha Chemical Co., Ltd.) 5.0 parts by mass Polymerization initiator (IrgacureOXE01, manufactured by BASF Corporation) 4.0 parts by mass Polymer X-1 described below 1.2 parts by mass Onium salt compound described below 1.14 parts by mass Fluorine-containing compound (fluorine-containing polymer) F-1 described below 0.4 parts by mass Methyl ethyl ketone 43.3 parts by mass Ethyl propionate 95.0 parts by mass Methyl isobutyl ketone 494.9 parts by mass

[0135] Polymer X-1

[0136]

[0137] Onium salt compounds

[0138]

[0139] Fluorine-containing polymer F-1

[0140]

[0141] (Formation of a Laminate of Optically Anisotropic Layer (A), Optically Anisotropic Layer (B), and Optically Anisotropic Layer (C)) The surface side of the optically anisotropic layer (1c) formed on the long cellulose acylate film prepared above and the surface side of the optically anisotropic layer (1b) of the laminate (1a-1b) formed on the long cellulose acylate film prepared above were bonded together using a UV-curable adhesive in a continuous machine. The UV-curable adhesive had a thickness of 1.0 μm and a refractive index of 1.54. Subsequently, the rubbed alignment film-attached cellulose acylate film on the optically anisotropic layer (1a) side was peeled off to expose the surface of the optically anisotropic layer (1a) facing the cellulose acylate film. In this way, a retardation film (1c-1b-1a) was obtained in which the optically anisotropic layer (1c), the optically anisotropic layer (1b), and the optically anisotropic layer (1a) were laminated in this order on a long cellulose acylate film. The thickness of the retardation film (1c-1b-1a) was 4.0 μm.

[0142] (Preparation of Linear Polarizing Plate 1) The support surface of a cellulose triacetate film TJ25 (manufactured by Fujifilm Corporation; thickness: 25 μm) was subjected to alkaline 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 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. Linear polarizing plate 1 was prepared by bonding the polarizer protective film to one side of the polarizer using the PVA adhesive described below.

[0143] (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.

[0144] (Preparation of Circular Polarizing Plate) The surface of the optically anisotropic layer (1a) of the long retardation film (1c-1b-1a) prepared above and the surface of the polarizer of the long linear polarizing plate 1 prepared above (the surface opposite the polarizer protective film) were continuously bonded together using a UV-curable adhesive. Subsequently, the cellulose acylate film on the optically anisotropic layer (1c) side was peeled off to expose the surface of the optically anisotropic layer (1c) that had been in contact with the cellulose acylate film. In this manner, a circular polarizing plate (P1) consisting of the retardation film (1c-1b-1a) and the linear polarizing plate was prepared. At this time, the polarizer protective film, polarizer, optically anisotropic layer (1a), optically anisotropic layer (1b), and optically anisotropic layer (1c) were laminated in this order, and the angle formed between the absorption axis of the polarizer and the slow axis of the optically anisotropic layer (1a) was 76°. Furthermore, the alignment axis angle of the liquid crystal compound on the optically anisotropic layer (1b) side of the optically anisotropic layer (1a) was 14°, with the width direction taken as the reference 0°, and coincided with the slow axis direction of the optically anisotropic layer (1a). The thickness of the circular polarizer was 43 μm. The alignment axis angle of the liquid crystal compound contained in the optically anisotropic layer was observed from the surface side of the polarizer, with the width direction of the linear polarizer taken as the reference 0°, and is expressed as negative when clockwise (right-handed) and positive when counterclockwise (left-handed).

[0145] Example 2 A circularly polarizing plate was produced in the same manner as in Example 1, except for the method for forming the laminate of the optically anisotropic layer (A) and the optically anisotropic layer (B).

[0146] (Formation of Optically Anisotropic Layer (A)) Onto the rubbed alignment film prepared in Example 1, a composition for forming an optically anisotropic layer (2a) containing a discotic liquid crystal compound of 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 discotic liquid crystal compound. Subsequently, the obtained composition layer was irradiated with UV light (100 mJ / cm) at 80°C. ２ ) to fix the alignment of the liquid crystal compound. Subsequently, the film was annealed with hot air at 120°C for 1 minute to form an optically anisotropic layer (2a). The thickness of the optically anisotropic layer (2a) was 1.1 μm. The in-plane retardation at a wavelength of 550 nm was 168 nm. The average tilt angle of the discotic surface 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. The in-plane slow axis angle of the optically anisotropic layer (2a) 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 in-plane slow axis was −14° when viewed from the optically anisotropic layer (2a) side. The optically anisotropic layer (2a) corresponds to the optically anisotropic layer (A) having a retardation without λ / 4 function.

[0147] Optically anisotropic layer-forming composition (2a) ------------------------------------------------ Discotic liquid crystal compound 1 of Example 1 80 parts by mass Discotic liquid crystal compound 2 of Example 1 20 parts by mass Alignment film interface aligning agent 1 of Example 1 0.55 parts by mass Photoalignable polymer A-1 below 2.0 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) 3.0 parts by mass Photoacid generator D-1 below 3.0 parts by mass Methyl ethyl ketone 200 parts by mass

[0148] Photoalignable polymer A-1 (the numerical value shown for each repeating unit indicates the content (% by mass) of each repeating unit relative to all repeating units, and the repeating units from the left were 40% by mass, 25% by mass, and 35% by mass, respectively. The weight-average molecular weight was 69,300.)

[0149]

[0150] Photoacid generator D-1

[0151]

[0152] (Formation of Laminate of Optically Anisotropic Layer (A) and Optically Anisotropic Layer (B)) (Formation of Optically Anisotropic Layer (2b)) The obtained optically anisotropic layer (2a) was irradiated with UV light (ultra-high pressure mercury lamp; UL750; manufactured by HOYA) at room temperature through a wire grid polarizer at a concentration of 7.9 mJ / cm. ２By irradiating the surface with UV light (wavelength: 313 nm), the alignment component (cinnamate moiety) of the photoalignable polymer A-1 was aligned, and an optically anisotropic layer (2a) having alignment function was formed on the surface. Next, using a Giesser coater, an optically anisotropic layer-forming composition (1b) containing the same rod-shaped liquid crystal compound as in Example 1 was applied to the surface irradiated with UV light, and the layer was heated with hot air at 80°C for 60 seconds. Subsequently, the obtained composition layer was irradiated with UV light (500 mJ / cm) at 80°C. ２ ) was performed to fix the alignment of the liquid crystal compound, thereby forming an optically anisotropic layer (2b). The thickness of the optically anisotropic layer (2b) was 1.2 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 0° (the longitudinal direction was 90°), the alignment axis angle of the liquid crystal compound, as viewed from the optically anisotropic layer (1b) side, was 85° on the air side and −14° on the side in contact with the optically anisotropic layer (1a). The optically anisotropic layer (2b) corresponds to the optically anisotropic layer (B) having a retardation without λ / 4 function.

[0153] By the above procedure, a laminate (2a-2b) was prepared in which an optically anisotropic layer (2a) and an optically anisotropic layer (2b) were directly laminated on a continuous cellulose acylate film. The laminate (2a-2b) corresponds to a laminate having a λ / 4 function.

[0154] Example 3 A circularly polarizing plate was produced in the same manner as in Example 1, except that the thickness of the ultraviolet-curable adhesive was changed to 1.0 μm and the refractive index was changed to 1.51.

[0155] Example 4 A circularly polarizing plate was produced in the same manner as in Example 1, except for the methods of forming the optically anisotropic layer (A), the optically anisotropic layer (B), and the optically anisotropic layer (C).

[0156] (Formation of Optically Anisotropic Layer (A)) Onto the rubbed alignment film prepared in Example 1, a composition for forming an optically anisotropic layer (3a) containing a discotic liquid crystal compound of 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 discotic liquid crystal compound. Subsequently, the obtained composition layer was irradiated with UV light (100 mJ / cm) at 80°C. ２) to fix the alignment of the liquid crystal compound. Subsequently, the film was annealed with hot air at 120°C for 1 minute to form an optically anisotropic layer (3a). The thickness of the optically anisotropic layer (3a) was 1.4 μm. The in-plane retardation at a wavelength of 550 nm was 168 nm. The average tilt angle of the discotic surface 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. The in-plane slow axis of the optically anisotropic layer (3a) 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 in-plane slow axis was −14° when viewed from the optically anisotropic layer (3a) side. The optically anisotropic layer (3a) corresponds to the optically anisotropic layer (A) having a retardation without λ / 4 function.

[0157] Optically anisotropic layer-forming composition (3a) ------------------------------------------------ Discotic liquid crystal compound 1 of Example 1 80 parts by mass Discotic liquid crystal compound 2 of Example 1 20 parts by mass Alignment film interface aligning agent 1 of Example 1 1.0 part by mass Silicon-containing compound A below 0.2 parts by mass Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 5 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by BASF) 4.0 parts by mass Methyl ethyl ketone 200 parts by mass

[0158] 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.)

[0159]

[0160] (Formation of Laminate of Optically Anisotropic Layer (A) and Optically Anisotropic Layer (B)) (Formation of Optically Anisotropic Layer (3b)) The surface of the optically anisotropic layer (3a) of the optically anisotropic layer (A) prepared above was heated at 50 W·min / m 2 The corona-treated surface was then coated with a composition (3b) for forming an optically anisotropic layer containing a rod-shaped liquid crystal compound having the following composition using a Giesser coater, and heated with hot air at 80°C for 60 seconds. Subsequently, the resulting composition layer was irradiated with UV light (500 mJ / cm) at 80°C. ２ ) was carried out to fix the alignment of the liquid crystal compound, thereby forming an optically anisotropic layer (3b).

[0161] Optically anisotropic layer-forming composition (3b) -------------------------------- Rod-shaped liquid crystal compound L-1 of Example 1 100 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) of Example 1 0.60 parts by mass Silicon-containing compound B below 0.15 parts by mass Methyl ethyl ketone 156 parts by mass

[0162] 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.)

[0163]

[0164] (Preparation of Optically Anisotropic Layer (C)) The following liquid crystal composition (3c) was applied to the support prepared in Example 1 using a Giesser coater to form a composition layer. The first temporary support on which the composition layer was formed was heated with warm air at 60°C for 1 minute, and then irradiated with ultraviolet light (irradiation dose 120 mJ / cm) while purging with nitrogen so that the atmosphere had an oxygen concentration of 100 ppm by volume or less. ２ , using an ultra-high pressure mercury lamp) was performed to fix the alignment of the rod-shaped liquid crystal compound L-1, thereby forming an optically anisotropic layer (3c). The film thickness of the optically anisotropic layer (3c) was 0.7 μm. The Re(550) of the optically anisotropic layer (1c) was 0 nm and Rth(550) was −80 nm. The average tilt angle of the rod-shaped liquid crystal compound L-1 with respect to the surface of the optically anisotropic layer was 90°, and the compound was aligned perpendicular to the surface of the support.

[0165] Composition for forming optically anisotropic layer (3c) ------------------------------------------------ Rod-like liquid crystal compound L-1 described above 100 parts by mass Polyfunctional monomer (UA-306I, manufactured by Kyoeisha Chemical Co., Ltd.) 5.0 parts by mass Polymerization initiator (IrgacureOXE01, manufactured by BASF Corporation) 4.0 parts by mass Polymer X-1 of Example 1 1.2 parts by mass Onium salt compound of Example 1 1.14 parts by mass Silicon-containing compound C described below 0.04 part by mass Silicon-containing compound D described below 0.21 parts by mass Methyl ethyl ketone 43.3 parts by mass Ethyl propionate 95.0 parts by mass Methyl isobutyl ketone 494.9 parts by mass

[0166] Silicon-containing compound C (weight average molecular weight: 20,000; the numbers in the following formula indicate the content (% by mass) of each repeating unit relative to all repeating units in silicon-containing compound C).

[0167]

[0168] Silicon-containing compound D (weight average molecular weight: 30,000; the numbers in the following formula indicate the content (% by mass) of each repeating unit relative to all repeating units in silicon-containing compound D).

[0169]

[0170] Comparative Example 1 A laminate (1c-1b-1a) was produced in the same manner as in Example 3, except that the optically anisotropic layer (B) was formed by applying the optically anisotropic layer-forming composition (1b) not onto the optically anisotropic layer (1a) but onto the rubbed alignment film produced in Example 1, and that the optically anisotropic layer (1a) and the optically anisotropic layer (1b) were bonded together in a continuous machine using an ultraviolet-curable adhesive having a refractive index of 1.51 to produce a laminate (1a-1b), thereby producing a circularly polarizing plate.

[0171] [Evaluation of interference color unevenness] The produced circular polarizing plate was attached to a blackboard using a pressure-sensitive adhesive so that the polarizer protective film was positioned on the outside. The color was observed from all directions through a diffuser under fluorescent light (FPL-27EX-N). The azimuth angle dependence of the color change was evaluated according to the following criteria: A: No in-plane color unevenness was visible, or it was visible but very slight. (Acceptable) B: In-plane color unevenness was visible, but the reflected light was small and did not pose a problem in use. (Acceptable) C: In-plane color unevenness was visible and unacceptable.

[0172]

[0173] The circular polarizing plates produced in each Example and Comparative Example were attached to an aluminum plate using a pressure-sensitive adhesive so that the polarizer protective film was positioned on the outside, and the reflected color was checked from the front and oblique directions under a white light source.In all Examples, no or only slight color tint was observed, and the display performance from the front and oblique directions was good.

[0174] From the above results, it was confirmed that when a circularly polarizing plate including the optical laminate of the present invention is used in an organic EL display device, interference color unevenness is suppressed and display performance in both the front and oblique directions is also good. On the other hand, when the circularly polarizing plate of the comparative example is used in an organic EL display device, the desired effect cannot be obtained. From a comparison between Example 3 and other Examples, it was confirmed that interference color unevenness can be further suppressed when the refractive index of the adhesive layer 2 is 1.53 to 1.64.

[0175] 12 Optically anisotropic layer (A) 14 Optically anisotropic layer (B) 16 Optically anisotropic layer (C) 20 Polarizer 100 Circularly polarizing plate 121, 122, 141, 142 Surface

Claims

1. A method for producing an optical laminate comprising the step of directly coating a liquid crystal composition for forming an optically anisotropic layer (B) having a retardation without a λ / 4 function onto an optically anisotropic layer (A) comprising an aligned liquid crystal compound fixed therein and having a retardation without a λ / 4 function, which satisfies the following requirement 1 or 2, to form a laminate having a λ / 4 function. Requirement 1: The optically anisotropic layer (A) is surface-treated. Requirement 2: The optically anisotropic layer (A) is formed from a liquid crystal composition containing a photo-aligned polymer.

2. The method for producing an optical laminate according to claim 1, wherein the optically anisotropic layer (A) is a negative uniaxial optically anisotropic layer.

3. The method for producing an optical laminate according to claim 1, wherein the optically anisotropic layer (B) is an optically anisotropic layer comprising fixed rod-like liquid crystal compounds that are twisted and aligned with the thickness direction as the helical axis.

4. A method for producing the optical laminate according to claim 1, further comprising the step of forming a C plate by directly applying a liquid crystal composition for forming a C plate onto the laminate, or the step of laminating a C plate via an adhesive layer.

5. A method for producing a polarizing plate, comprising laminating an optical laminate obtained by the method for producing an optical laminate according to any one of claims 1 to 4 and a polarizer to obtain a polarizing plate.

6. An optical laminate having a λ / 4 function, which satisfies the following requirement 1 or 2 and includes an optically anisotropic layer (A) having a retardation without a λ / 4 function and formed by fixing an aligned liquid crystal compound, an optically anisotropic layer (B) having a retardation without a λ / 4 function, an adhesive layer 2, and a C plate arranged adjacent to each other in this order. Requirement 1: The optically anisotropic layer (A) is surface-treated. Requirement 2: The optically anisotropic layer (A) is formed from a liquid crystal composition containing a photo-aligned polymer.

7. The optical laminate according to claim 6, wherein the adhesive layer 2 has a refractive index of 1.53 to 1.

64.

8. The optical laminate according to claim 6, wherein silicon is present at the interface between the optically anisotropic layer (A) and the optically anisotropic layer (B).

9. A polarizing plate comprising a polarizer, an adhesive layer 1, an optically anisotropic layer (A) having a retardation without a λ / 4 function and formed by fixing an aligned liquid crystal compound, which satisfies the following requirement 1 or 2, an optically anisotropic layer (B) having a retardation without a λ / 4 function, an adhesive layer 2, and a C plate, which are arranged adjacent to each other in this order, and a laminate of the optically anisotropic layer (A) and the optically anisotropic layer (B) has a λ / 4 function. Requirement 1: The optically anisotropic layer (A) is surface-treated. Requirement 2: The optically anisotropic layer (A) is formed from a liquid crystal composition containing a photo-aligned polymer.

10. An organic electroluminescence display device comprising the optical laminate according to any one of claims 6 to 8.

11. An organic electroluminescence display device comprising the polarizing plate according to claim 9.

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