Optical film, polarizing plate, and display device

Abstract

The present invention addresses a first problem of providing an optical film that, when the same is applied to a display element to obtain a display device and the display device is set to display black and is viewed along an oblique direction, is less likely to exhibit in-plane color non-uniformity. The present invention addresses a second problem of providing a polarizing plate and a display device.　An optical film according to the present invention comprises: a liquid crystal layer; an alignment layer adjacent to at least one surface of the liquid crystal layer; and an adhesion layer adjacent to the alignment layer. The adhesion layer is an adhesive agent layer or a pressure-sensitive adhesive agent layer. The alignment layer is optically isotropic. The refractive index of the liquid crystal layer in the in-plane slow axis direction is greater than the refractive index of the alignment layer. The refractive index of the alignment layer is greater than the refractive index of the adhesion layer. The absolute value of the difference between the refractive index of the liquid crystal layer in the in-plane slow axis direction and the refractive index of the alignment layer is at most 0.09.

Description

Optical films, polarizing plates, display devices

[0001] The present invention relates to optical films, polarizing plates, and display devices.

[0002] Phase difference films, which possess optical anisotropy and generate phase differences, are applied to a variety of uses. For example, phase difference films are used in combination with polarizers as circular polarizers.

[0003] For example, Patent Document 1 discloses an optical film having a photo-alignment film obtained by curing a composition containing a photo-aligning polymer of a predetermined structure and an epoxy compound, wherein the photo-aligning polymer is adjusted to a predetermined amount, and a liquid crystal cured layer disposed on the photo-alignment film, as well as a polarizing plate including a polarizer. Patent Document 1 also discloses that an adhesion layer may be formed between the optical film and the polarizer.

[0004] International Publication No. 2024 / 177039

[0005] Recently, there has been a growing demand for further reduction of in-plane color unevenness in display devices when viewing a black image from an oblique angle. The inventors of this invention fabricated a polarizing plate containing the optical film and polarizer described in the above-mentioned literature and investigated its application to a display device. They found that it sometimes fails to meet the standards required today. In-plane color unevenness refers to the presence of areas with different colors within the surface.

[0006] In view of the above circumstances, the present invention aims to provide an optical film that, when applied to a display element to obtain a display device, exhibits less in-plane color unevenness when the display device is viewed from an oblique direction in black display mode. The present invention also aims to provide a polarizing plate and a display device.

[0007] The inventors have found that the above problem can be solved by the following configuration.

[0008] [1] An optical film comprising a liquid crystal layer, an alignment layer adjacent to at least one surface of the liquid crystal layer, and an adhesion layer adjacent to the alignment layer, wherein the adhesion layer is an adhesive layer or a tack layer, the alignment layer is optically isotropic, the refractive index of the liquid crystal layer in the in-plane slow axis direction is greater than the refractive index of the alignment layer, the refractive index of the alignment layer is greater than the refractive index of the adhesion layer, and the absolute value of the difference between the refractive index of the liquid crystal layer in the in-plane slow axis direction and the refractive index of the alignment layer is 0.09 or less. [2] The optical film according to [1], wherein the alignment layer comprises a polymer having repeating units derived from a radical polymerizable monomer having an aromatic ring, or inorganic particles. [3] The optical film according to [2], wherein the radical polymerizable monomer has at least one skeleton selected from a fluorene skeleton, a dinaphthothiophene skeleton, a naphthalene skeleton, anthracene skeleton, a benzotriazole skeleton, a triazine skeleton, a benzophenone skeleton, a merocyanine skeleton, a benzoxazole skeleton, a benzothiol skeleton, a triphenylene skeleton, a bisphenol skeleton, and a tran skeleton. [4] The optical film according to [2] or [3], wherein the inorganic particles contain an atom selected from the group consisting of zirconium and titanium. [5] The optical film according to any one of [1] to [4], wherein the orientation layer contains a photo-orienting material. [6] The optical film according to [2] or [3], wherein the orientation layer is a layer formed using a composition containing a photo-orienting material and the radical polymerizable monomer, and the content of the radical polymerizable monomer is 10.0% by mass or more with respect to the total mass of the photo-orienting material. [7] The optical film according to [5] or [6], wherein the photo-orienting material is a compound having a photo-orienting group. [8] The optical film according to any one of [1] to [4], wherein the alignment layer is a layer that has been subjected to rubbing treatment. [9] The optical film according to any one of [1] to [8], further comprising another liquid crystal layer different from the liquid crystal layer on the side of the adhesion layer opposite to the alignment layer.

[10] The optical film according to any one of [1] to [9], wherein the optical film has a λ / 4 function.

[11] The optical film according to [9], wherein the liquid crystal layer is a negative A plate, and the other liquid crystal layer comprises a twisted liquid crystal layer and a C plate.

[12] A polarizing plate comprising an optical film as described in any of [1] to

[11] and a polarizer.

[13] A display device comprising the polarizing plate described in

[12] .

[0009] According to the present invention, when applied to a display element to obtain a display device, an optical film can be provided that, when the display device is set to display black and viewed from an oblique direction, is less prone to uneven color distribution within the surface. Furthermore, according to the present invention, a polarizing plate and a display device can be provided.

[0010] This is a conceptual diagram illustrating an example of the optical film of the present invention. This is a conceptual diagram illustrating another example of the optical film of the present invention. This is a conceptual diagram illustrating an example of the polarizing plate of the present invention.

[0011] The present invention will now be described in detail. The following descriptions of constituent elements may be based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In this specification, numerical ranges expressed using "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits.

[0012] In this specification, the "absorption axis" refers to the polarization direction in which the absorbance is maximum when linearly polarized light is incident on the element. The "in-plane lagging axis" refers to the direction in which the refractive index is maximum.

[0013] In this specification, Re(λ) and Rth(λ) represent the in-plane retardation and thickness retardation at wavelength λ, respectively. Unless otherwise specified, wavelength λ is 550 nm. In this specification, unless otherwise specified, Re(λ) and Rth(λ) are values ​​measured at wavelength λ using an AxoScan (manufactured by Axometrics). By inputting the average refractive index ((nx + ny + nz) / 3) and film thickness (d) into the AxoScan, the following can be calculated: In-plane retardation axis direction (°) Re(λ) = R0(λ) Rth(λ) = ((nx + ny) / 2 - nz) × d Note that R0(λ) is displayed as a value calculated by the AxoScan, but it means Re(λ).

[0014] In this specification, A plates and C plates are defined as follows: There are two types of A plates: positive A plates and negative A plates. When the refractive index in the in-plane slow axis direction (the direction in which the refractive index is maximum in the plane) of the film is nx, the refractive index in the direction perpendicular to the in-plane slow axis is ny, and the refractive index in the thickness direction is nz, a positive A plate satisfies the relationship in equation (A1), and a negative A plate satisfies the relationship in equation (A2). Note that a positive A plate has a positive Rth value, and a negative A plate has a negative Rth value. Equation (A1) nx > ny ≈ nz Equation (A2) ny < nx ≈ nz Note that the above "≈" includes not only cases where the two are completely identical, but also cases where the two are substantially identical. "Substantially identical" means, for example, that when (ny - nz) × d (where d is the film thickness) is -10 to 10 nm, preferably -5 to 5 nm, it is included in "ny ≈ nz", and when (nx - nz) × d is -10 to 10 nm, preferably -5 to 5 nm, it is included in "nx ≈ nz". There are two types of C plates: positive C plates and negative C plates. A positive C plate satisfies the relationship in equation (C1), and a negative C plate satisfies the relationship in equation (C2). Note that a positive C plate shows a negative Rth value, and a negative C plate shows a positive Rth value. Equation (C1) nz > nx ≈ ny Equation (C2) nz < nx ≈ ny Note that the above "≈" includes not only cases where the two are completely identical, but also cases where the two are substantially identical. "Substantially identical" means that, for example, when (nx - ny) × d (where d is the thickness of the film) is 0 to 10 nm, preferably 0 to 5 nm, it is included in "nx ≈ ny".

[0015] In this specification, "solids" refers to the components that form the layer, and does not include the solvent. The components that form the layer may also be components whose chemical structure changes through reaction (polymerization) during layer formation. Furthermore, any component that forms the layer is considered a solid, even if its properties are liquid.

[0016] In this specification, unless otherwise specified, the refractive index is the refractive index at a wavelength of 550 nm. In this specification, unless otherwise specified, the in-plane slow axis is defined at 550 nm.

[0017] In this specification, (meth)acrylate means both acrylate and methacryle, (meth)acryloyl means both acryloyl and methacryloyl, and (meth)acrylic means both acrylic and methacrylic. In this specification, the weight-average molecular weight (Mw) is the polystyrene equivalent value obtained by GPC (Gel Permeation Chromatography).

[0018] [Optical Film] The optical film of the present invention is an optical film comprising a liquid crystal layer, an alignment layer adjacent to at least one surface of the liquid crystal layer, and an adhesion layer adjacent to the alignment layer, wherein the adhesion layer (hereinafter also referred to as "adhesion layer A") is an adhesive layer or a tack layer, the alignment layer is optically isotropic, the refractive index of the liquid crystal layer in the in-plane slow axis direction is greater than the refractive index of the alignment layer, the refractive index of the alignment layer is greater than the refractive index of the adhesion layer, and the absolute value of the difference between the refractive index of the liquid crystal layer in the in-plane slow axis direction and the refractive index of the alignment layer is 0.09 or less.

[0019] In this specification, when we say that "the layer is optically isotropic," we mean that the absolute value of Re(λ) of the layer is 5 nm or less, and the absolute value of Rth(λ) is 5 nm or less.

[0020] In this specification, the predetermined refractive index of each layer, the liquid crystal layer, the alignment layer, and the adhesion layer, is a value obtained by the following method. As described above, the optical film of the present invention includes an alignment layer, a liquid crystal layer, and an adhesion layer, and the thickness and refractive index of each layer can be measured by known methods. An example of an embodiment of the method for measuring the refractive index of each layer is shown below. When measuring, the alignment layer is measured in a form laminated on the substrate, and the liquid crystal layer is measured in a form laminated on the alignment layer. The adhesion layer is measured in a form laminated on a glass substrate. If the adhesion layer is a non-curing type adhesion layer (specifically, adhesive layers that do not fall under curable adhesives that harden by irradiation with active energy rays or heating, and adhesive layers, etc.), it is measured in a state where it is applied to glass to form a coating film, and if it is a curing type adhesion layer (specifically, curable adhesives that harden by irradiation with active energy rays or heating), it is measured in a state where the cured film is laminated on glass.

[0021] The following is an example of a measurement method. First, transmission and reflection ellipsometry are performed using an ellipsometer in the wavelength range of 500 to 1500 nm. For example, the RC-2 manufactured by Woolam and the SE-2000 manufactured by Semilab can be used as ellipsometers. When performing the above measurements, for each azimuth angle, in reflection ellipsometry, measurements are taken at three or more angles with a difference of 15° or more between the maximum and minimum angles of incidence. In transmission ellipsometry, measurements are taken at three or more angles with a difference of 30° or more between the maximum and minimum angles, including normal incidence. The above measurements are performed for two orthogonal azimuth angles of the sample. In the above reflection ellipsometry, it is preferable to apply a treatment to reduce the back surface reflection intensity. An example of a treatment to reduce the back surface reflection intensity is to rub the back surface with sandpaper. For the results obtained from the above measurements, the refractive index of the alignment layer is calculated by constructing an optical model assuming the presence of an alignment layer and a substrate (isotropic layer) in the thickness direction, and fitting it using the least squares method. Similarly, the refractive index of the liquid crystal layer is calculated by constructing an optical model assuming the presence of a liquid crystal layer, an alignment layer, and a substrate (isotropic layer) in the thickness direction, and then calculating the refractive index of the liquid crystal layer. Furthermore, the refractive index of the adhesion layer is calculated by constructing an optical model assuming the presence of an adhesion layer and glass (isotropic layer) in the thickness direction. For the refractive index of each layer, the direction in which the refractive index is maximum in the plane is defined as the x-axis, the direction perpendicular to it as the y-axis, and the direction normal to the plane as the z-axis, and the refractive index in each direction is defined as nx, ny, and nz. Following the Cauchy model, we set n(λ) = An + Bn / λ² (An and Bn are variables, λ is wavelength, and n(λ) represents the refractive index at wavelength λ). The refractive index in the direction of the slow phase axis in the plane is calculated using the Cauchy model nx(λ) = Anx + Bnx / λ², and the refractive index in the direction of the fast phase axis in the plane is calculated using the Cauchy model ny(λ) = Any + Bny / λ². Equation (1) Refractive index of the orientation layer = (nx + ny) / 2 Note that if the orientation layer has no slow phase axis and the refractive index is the same in all directions, the refractive index in one direction in the plane is taken as nx, and the refractive index in the direction perpendicular to that direction is taken as ny. The average values ​​of the birefringence and in-plane refractive index can also be calculated.Furthermore, the refractive index, birefringence, and in-plane refractive index in each layer and region are based on values ​​at a wavelength of 550 nm.

[0022] A key feature of the optical film of the present invention is that the refractive index of the alignment layer, which is positioned between the liquid crystal layer and the adhesion layer, is adjusted to a predetermined numerical range. In the optical film of the present invention, the relative relationship between the refractive index of the liquid crystal layer in the in-plane slow-phase axis direction, the refractive index of the alignment layer (in-plane average refractive index), and the refractive index of the adhesion layer is such that the refractive index of the liquid crystal layer in the in-plane slow-phase axis direction > the refractive index of the alignment layer > the refractive index of the adhesion layer, and the absolute value of the difference between the refractive index of the liquid crystal layer in the in-plane slow-phase axis direction and the refractive index of the alignment layer is set to 0.09 or less, thereby suppressing the occurrence of interfacial reflection within the optical film. It is presumed that by reducing the amount of light reflected within the optical film in this way, in-plane color unevenness can be suppressed as a result. When a polarizing plate formed by laminating the optical film of the present invention and a polarizer is applied to a display device, the angle between the transmission axis of the polarizer and the in-plane slow-phase axis of the liquid crystal layer is often set to a small value. For this reason, the transmitted light (linearly polarized light) entering the liquid crystal layer from the polarizer is easily affected by the refractive index nx in the in-plane slow-phase axis direction of the liquid crystal layer. The optical film of the present invention sets the refractive index in the in-plane slow axis direction of the liquid crystal layer, which can be a major cause of interfacial reflection, the refractive index of the alignment layer (in-plane average refractive index), and the refractive index of the adhesion layer to a predetermined relationship. Therefore, when a polarizing plate formed by laminating the optical film of the present invention with a polarizer is applied to a display device, reflected light within the optical film can be suppressed more effectively. Hereinafter, when the optical film of the present invention is applied to a display element to obtain a display device, and the display device is viewed from an oblique direction with a black display, the fact that in-plane color unevenness is less likely to occur is also referred to as "the effect of the present invention is superior."

[0023] Figure 1 shows an example of the optical film of the present invention. As shown in Figure 1, the optical film 10 has a liquid crystal layer 12, an alignment layer 14, and an adhesion layer 16 in this order. The liquid crystal layer 12 and the alignment layer 14 are arranged adjacent to each other, and the alignment layer 14 and the adhesion layer 16 are arranged adjacent to each other. In the optical film 10, the refractive index of the liquid crystal layer 12 in the in-plane slow axis direction, the refractive index of the alignment layer 14 (in-plane average refractive index), and the refractive index of the adhesion layer 16 have the relationship: refractive index of the liquid crystal layer 12 in the in-plane slow axis direction > refractive index of the alignment layer 14 (in-plane average refractive index) > refractive index of the adhesion layer. Also, the absolute value of the difference between the refractive index of the liquid crystal layer 12 in the in-plane slow axis direction and the refractive index of the alignment layer 14 is 0.09 or less. The individual components included in the optical film 10 will be described in detail below.

[0024] [Liquid Crystal Layer] The optical film includes a liquid crystal layer. The liquid crystal layer is a layer containing a liquid crystal compound. As the liquid crystal compound, either a polymer liquid crystal compound or a low-molecular-weight liquid crystal compound can be used. Here, "polymer liquid crystal compound" refers to a liquid crystal compound having repeating units in its chemical structure. Also, "low-molecular-weight liquid crystal compound" refers to a liquid crystal compound that does not have repeating units in its chemical structure. The liquid crystal compound may be a rod-shaped liquid crystal compound or a disc-shaped liquid crystal compound. As the rod-shaped liquid crystal compound, known compounds can be used, for example, the compounds described in claim 1 of Japanese Patent Publication No. 11-513019 and paragraphs 0026 to 0098 of Japanese Patent Application Publication No. 2005-289980. As the disc-shaped liquid crystal compound, known compounds can be used, for example, the compounds described in paragraphs 0020 to 0067 of Japanese Patent Application Publication No. 2007-108732 and paragraphs 0013 to 0108 of Japanese Patent Application Publication No. 2010-244038.

[0025] The liquid crystal compound in the liquid crystal layer may be fixed. In this specification, "fixed" means that the orientation of the liquid crystal compound is maintained. Specifically, it is preferable that the layer is non-fluid and can maintain a stable fixed orientation without being altered by an external field or force, usually in a temperature range of 0 to 50°C, or -30 to 70°C under more severe conditions. Furthermore, the liquid crystal compound in the liquid crystal layer does not have to exhibit liquid crystalline properties anymore. For example, when a liquid crystal layer is formed using a polymerizable liquid crystal compound, the liquid crystal compound may have become highly molecular weight due to the curing reaction and may no longer exhibit liquid crystalline properties.

[0026] The liquid crystal layer is preferably a layer formed using a composition containing a polymerizable liquid crystal compound. A polymerizable liquid crystal compound is a liquid crystal compound having polymerizable groups. Examples of polymerizable groups include unsaturated polymerizable groups, epoxy groups, and azilidinyl groups, with unsaturated polymerizable groups being preferred, ethylenically unsaturated polymerizable groups being more preferred, and (meth)acryloyl groups being particularly preferred.

[0027] The refractive index in the in-plane slow axis direction of the liquid crystal layer is greater than the refractive index of the alignment layer. The absolute value of the difference between the refractive index in the in-plane slow axis direction of the liquid crystal layer and the refractive index of the alignment layer is 0.09 or less, preferably 0.04 or less, and more preferably 0.03 or less, in terms of superior effects of the present invention. The lower limit is not particularly limited, but 0.01 or more is preferred.

[0028] The refractive index in the in-plane slow axis direction of the liquid crystal layer is not particularly controlled, but for example, it is preferably 1.50 to 1.80, more preferably 1.55 to 1.75, and even more preferably 1.60 to 1.70.

[0029] The absolute value of the difference between the refractive index of the liquid crystal layer in the in-plane slow phase axis direction and the refractive index of the adhesion layer is not particularly limited, but is preferably 0.20 or less, and more preferably 0.15 or less. The lower limit is not particularly limited, but is preferably 0.01 or more. The refractive index in the direction perpendicular to the in-plane slow phase axis direction of the liquid crystal layer is not particularly limited, but is preferably 1.45 to 1.70, more preferably 1.48 to 1.65, and even more preferably 1.50 to 1.60.

[0030] The thickness of the liquid crystal layer is not particularly limited, but is preferably 10 μm or less, more preferably 0.1 to 5.0 μm, and even more preferably 0.5 to 3.0 μm.

[0031] The liquid crystal layer is preferably a phase difference layer. Specifically, examples of the phase difference layer include an A plate and a liquid crystal layer in which the liquid crystal compound is twisted and oriented at a twist angle of 180° or less (hereinafter also referred to as a "twisted liquid crystal layer"). The definition of the A plate is as described above. The A plate can also be used as a so-called λ / 4 plate or a λ / 2 plate. A λ / 4 plate is a plate that has the function of converting linearly polarized light of a certain wavelength to circularly polarized light (or circularly polarized light to linearly polarized light). More specifically, it is a plate in which the in-plane retardation Re at a predetermined wavelength λnm is λ / 4 (or an odd multiple thereof). When the A plate is used as a λ / 4 plate, the in-plane retardation of the A plate at a wavelength of 550 nm (Re(550)) may have an error of about 25 nm, centered on the ideal value (137.5 nm), for example, 110 to 160 nm is preferred, and 120 to 150 nm is more preferred. Furthermore, a λ / 2 plate refers to an optically anisotropic film in which the in-plane retardation Re(λ) at a specific wavelength λnm satisfies Re(λ) ≈ λ / 2. This equation only needs to be achieved at any wavelength in the visible light region (for example, 550 nm). In particular, when using an A plate as a λ / 2 plate, the in-plane retardation Re(550) of the A plate at a wavelength of 550 nm is preferably between 210 and 300 nm.

[0032] In the twisted liquid crystal layer (twisted liquid crystal layer) in which the liquid crystal compound is twisted and aligned at a twist angle of 180° or less, the twist angle of the liquid crystal compound (the twist angle of the alignment direction of the liquid crystal compound) is not particularly limited. However, in terms of being more easily used as a λ / 4 plate, a range of 80 ± 30° (a range of 50 to 110°) is preferable, and a range of 80 ± 20° (a range of 60 to 100°) is more preferable. The value of the product Δnd of the refractive index anisotropy Δn of the twisted liquid crystal layer and the thickness d of the twisted liquid crystal layer at a wavelength of 550 nm is not particularly limited, but 40 to 280 nm is preferable, and 100 to 200 nm is more preferable. The measurement methods for the above twist angle and Δnd are measured using the AxoScan (polarimeter) device of Axometrics and the device analysis software of the same company.

[0033] Note that when the liquid crystal compound is twisted and aligned, it is intended that the liquid crystal compound twists from one main surface of the twisted liquid crystal layer to the other main surface with the thickness direction of the twisted liquid crystal layer 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 twisted liquid crystal layer. In the twisted alignment, the long axis of the liquid crystal compound is arranged so as to be parallel to the main surface of the twisted liquid crystal layer. Note that it is not required to be exactly parallel, and the angle formed by the long axis of the liquid crystal compound and the main surface of the twisted liquid crystal layer is preferably within a range of 0 to 20°, and more preferably within a range of 0 to 10°.

[0034] [Alignment layer] The optical film includes an alignment layer arranged adjacent to the liquid crystal layer. The alignment layer exhibits optical isotropy. The refractive index (in-plane average refractive index) of the alignment layer is smaller than the refractive index in the in-plane slow axis direction of the liquid crystal layer and larger than the refractive index of the adhesion layer. Specifically, the refractive index (in-plane average refractive index) of the alignment layer is preferably 1.45 to 1.70, more preferably 1.50 to 1.65, and even more preferably 1.55 to 1.61.

[0035] The thickness of the alignment layer is not particularly limited, and may be appropriately set to a thickness that can obtain the necessary alignment function according to the material for forming the alignment layer. The thickness of the alignment layer is preferably 0.01 to 5 μm, and more preferably 0.05 to 2 μm.

[0036] As the alignment layer, a known alignment film can be used. Note that the alignment layer is generally a layer mainly composed of a polymer. As the alignment layer, known alignment layers such as a so-called photo-alignment layer formed by irradiating a photo-alignment material with polarized or non-polarized light to form an alignment film, and an alignment layer subjected to rubbing treatment can be used. Among them, the photo-alignment layer is preferable in that the alignment property of the liquid crystal compound in the liquid crystal layer disposed adjacent to the alignment layer is more excellent and alignment unevenness can be more suppressed.

[0037] The photo-alignment material is not particularly limited as long as it exhibits an alignment regulating force by irradiating polarized or non-polarized light. For example, compounds having a photo-alignment group selected from the group consisting of a photo-isomerizable group and a photo-reactive group can be mentioned. As the photo-alignment material, known compounds can be used, but compounds having a photo-alignment group such as a cinnamoyl group skeleton and a coumarin skeleton are preferable in terms of good alignment regulating force. The photo-alignment material is preferably a polymer having a repeating unit having a photo-alignment group. Note that the photo-alignment material may be uniformly dispersed in the alignment layer or may be unevenly distributed on the layer surface. As a method for unevenly distributing the photo-alignment material, a method of using a photo-alignment material having an unevenly distributed group as described later can be mentioned.

[0038] The alignment layer formed by rubbing treatment can be formed by rubbing the surface of the polymer layer several times in a certain direction with paper or cloth. As the material for forming the alignment layer, known materials usually used for alignment films such as polyimide and polyvinyl alcohol can be preferably used. The alignment layer formed by rubbing treatment preferably contains a polymer containing a repeating unit having a mesogen group, and more preferably contains a polymer containing a repeating unit having a mesogen group and a repeating unit having an unevenly distributed group.

[0039] The alignment layer preferably contains a high refractive index material selected from the group consisting of a polymer having a repeating unit derived from a radically polymerizable monomer having an aromatic ring (hereinafter also referred to as "polymer A") and inorganic particles for the purpose of adjusting the refractive index of the alignment layer to a predetermined range.

[0040] A radical polymerizable monomer having an aromatic ring is a compound comprising an aromatic ring and one or more radical polymerizable groups. Among the radical polymerizable groups, ethylenically unsaturated groups such as (meth)acryloyl groups, vinyl groups, styryl groups, and allyl groups are more preferred, with (meth)acryloyl groups being even more preferred. The number of radical polymerizable groups in the compound is not particularly limited, but 1 to 10 is preferred, and 1 to 6 is more preferred. The aromatic ring-containing radical polymerizable monomer is preferably having at least one skeleton selected from the fluorene skeleton, dinaphthothiophene skeleton, naphthalene skeleton, anthracene skeleton, benzotriazole skeleton, triazine skeleton, benzophenone skeleton, merocyanine skeleton, benzoxazole skeleton, benzothiol skeleton, triphenylene skeleton, bisphenol skeleton (preferably bisphenol S skeleton), and tran skeleton, in order to adjust the refractive index of the orientation layer to a higher value and to further enhance the effects of the present invention. It is more preferably having at least one skeleton selected from the fluorene skeleton, dinaphthothiophene skeleton, naphthalene skeleton, and anthracene skeleton, and even more preferably having a fluorene skeleton. The content of repeating units derived from the aromatic ring-containing radical polymerizable monomer in the total repeating units of polymer A can be appropriately adjusted according to the set value of the refractive index of the orientation layer.

[0041] Specific examples of radical polymerizable monomers having an aromatic ring include compounds represented by general formulas (I) to (VI) as described in paragraphs 0029 to 0046 of Japanese Patent Publication No. 2007-091876, fluorene compounds as described in paragraphs 0113 to 0115 of Japanese Patent Publication No. 2014-034596, and condensed ring-containing compounds represented by general formula (1) as described in Japanese Patent Publication No. 2014-080572 (preferably the general formulas described in the same publication). Examples include condensed ring-containing compounds represented by formula (3), compounds described in paragraph 0016 of Japanese Patent Publication No. 2013-253161, compounds described in paragraphs 0025 to 0153 of Japanese Patent Publication No. 2006-301614, compounds described in paragraphs 0020 to 0122 of Japanese Patent Publication No. 2007-108732, and compounds described in paragraphs 0012 to 0108 of Japanese Patent Publication No. 2010-244038.

[0042] Polymer A may contain other repeating units (hereinafter referred to as "other repeating units") other than repeating units derived from radical polymerizable monomers having aromatic rings. Preferably, the other repeating units are repeating units derived from radical polymerizable monomers that do not have aromatic rings, and more preferably, they are repeating units derived from polyfunctional monomers that have three or more (meth)acryloyl groups in one molecule and do not have aromatic rings.

[0043] The inorganic particles preferably contain metal atoms selected from the group consisting of zirconium, titanium, and aluminum, and more preferably contain atoms selected from the group consisting of zirconium and titanium, in that the refractive index of the orientation layer is adjusted to be higher, thereby improving the effects of the present invention.

[0044] The inorganic particles are preferably inorganic particles whose surface has been modified using a surface modifier (hereinafter also referred to as "surface-modified inorganic particles"). Examples of the above inorganic particles include zirconium oxide particles, titanium oxide particles, and aluminum oxide particles.

[0045] Examples of surface modifiers include compounds having one or more selected from the group consisting of vinyl groups, styryl groups, (meth)acrylic groups, (meth)acryloxy groups, epoxy groups, carbon-carbon double bonds, phenyl groups, methylphenyl groups, and silicon-hydrogen bonds. Specific examples include alkoxysilane compounds and siloxane compounds.

[0046] An example of a surface modifier is the compound represented by formula (F-1). (R) ｍ -M-(X) ｎ(F-1) R represents an organic group having one or more carbon atoms. The organic group is not particularly limited, but preferred are groups having one or more selected from the group consisting of vinyl group, styryl group, (meth)acrylic group, (meth)acryloxy group, epoxy group, carbon-carbon double bond, phenyl group, methylphenyl group, and silicon-hydrogen bond. M represents an atom selected from the group consisting of silicon, zirconium, and titanium. X represents an alkoxy group or halogen atom. The number of carbon atoms in the alkoxy group is not particularly limited, but is preferably 1 to 10, and more preferably 1 to 3. m represents an integer from 1 to 3, and n represents an integer from 1 to 3. However, m + n represents 4.

[0047] Among surface modifiers, silane coupling agents are preferred. Examples of silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriphenoxysilane, p-styryltrimethoxysilane, p-styryltriethoxysilane, p-styryltriphenoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-acryloxypropyltriphenoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-methacryloxypropyltriphenoxysilane, 3-aminopropyltrimeth Examples include xysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, allyltriphenoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, trimethylmethoxysilane, n-propyltrimethoxysilane, n-butyltriethoxysilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, phenyltrimethoxysilane, and diphenyldimethoxysilane.

[0048] Methods for modifying the surface of inorganic particles (preferably inorganic oxide particles) using a surface modifier include wet methods and dry methods. The wet method is a method of modifying the surface of inorganic particles by adding the surface modifier and inorganic particles to a solvent and mixing them. The dry method is a method of modifying the surface of inorganic particles by adding the surface modifier and dried inorganic particles to a dry mixer such as a mixer and mixing them. The content (mass%) of the modified portion in the surface-modified inorganic particles is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, and even more preferably 3 to 25% by mass, based on the total mass of the surface-modified inorganic particles.

[0049] Examples of solvents (dispersion solvents) used in the wet process include alcohols such as methanol, ethanol, 2-propanol, butanol, and octanol; esters such as ethyl acetate, butyl acetate, ethyl lactate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and γ-butyrolactone; ethers such as diethyl ether, ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, and cyclohexanone; aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; and amides such as dimethylformamide, N,N-dimethylacetacetamide, and N-methylpyrrolidone. The dispersion solvent may be used alone or in combination of two or more types.

[0050] In surface-modified inorganic particles, the content (mass%) of the modified portion is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, and even more preferably 3 to 25% by mass, relative to the total mass of the surface-modified inorganic particles, in terms of excellent compatibility with the polymer, which is the main component of the orientation layer, superior transparency of the orientation layer, and ease of adjusting the refractive index of the orientation layer to a high level.

[0051] The content of the high refractive index material in the orientation layer is preferably 9.0 to 83.0% by mass, more preferably 12.0 to 73.0% by mass, and even more preferably 14.0 to 64.0% by mass, relative to the total mass of the orientation layer. In the orientation layer, one type of high refractive index material may be used alone, or two or more types may be used in combination.

[0052] The orientation layer is a layer formed using a composition containing a photo-orienting material and a radical polymerizable monomer having an aromatic ring, in which the effects of the present invention are more easily enhanced, and it is also preferable that the content of the radical polymerizable monomer having an aromatic ring in the composition is 10.0% by mass or more relative to the total mass of the photo-orienting material. There is no particular upper limit to the content of the radical polymerizable monomer having an aromatic ring, but it is preferably 10,000% by mass or less, and more preferably 5,000% by mass or less, relative to the total mass of the photo-orienting material.

[0053] [Adhesion Layer] The optical film of the present invention has an adhesion layer (adhesion layer A) which is arranged adjacent to the side of the alignment layer opposite to the liquid crystal layer side. The adhesion layer is an adhesive layer or a tack layer.

[0054] The refractive index of the adhesion layer is preferably 1.45 to 1.65, more preferably 1.48 to 1.60, and even more preferably 1.51 to 1.58.

[0055] The thickness of the adhesion layer is preferably 0.01 to 20 μm, more preferably 0.01 to 10 μm, and even more preferably 0.05 to 5 μm.

[0056] <Adhesive Layer> The adhesive layer is a layer formed using an adhesive. Preferably, the adhesive layer is a layer formed by curing a curable adhesive that hardens by irradiation with active energy rays or by heating. Examples of curable adhesives include electron beam curable adhesives, ultraviolet curable adhesives, and visible light curable adhesives, with ultraviolet curable adhesives being preferred. Examples of ultraviolet curable adhesives include curable adhesives containing cationic polymerizable compounds (e.g., epoxy adhesives) and curable adhesives containing radical polymerizable compounds (e.g., (meth)acrylate adhesives). For the adhesive layer, for example, paragraphs

[0062] to

[0080] of Japanese Patent Application Publication No. 2016-035579 can be referenced, and the contents of these paragraphs are incorporated herein.

[0057] <Adhesive Layer> Examples of adhesives included in the adhesive layer include acrylic adhesives, epoxy adhesives, rubber adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone adhesives, polyacrylamide adhesives, and cellulose adhesives.

[0058] The optical film of the present invention may have other layers besides the alignment layer, liquid crystal layer, and adhesion layer (hereinafter also referred to as "other layers"). Figure 2 shows another example of the optical film of the present invention. As shown in Figure 2, the optical film 20 has other liquid crystal layers 22 on the side of the adhesion layer 16 of the optical film 10 that is opposite to the alignment layer 14 side. The other liquid crystal layers 22 have a first liquid crystal layer 24 and a second liquid crystal layer 26 in order from the adhesion layer 16 side.

[0059] [Other Liquid Crystal Layers] Other liquid crystal layers that the optical film may have are layers containing liquid crystal compounds. These other liquid crystal layers may be single-layer or multi-layer as shown in Figure 2. Specific examples of liquid crystal compounds contained in these other liquid crystal layers are the same as those contained in the liquid crystal layers described above.

[0060] The liquid crystal compounds in other liquid crystal layers may be fixed. Furthermore, the liquid crystal compounds in other liquid crystal layers may no longer exhibit liquid crystal properties. For example, when a liquid crystal layer is formed using a polymerizable liquid crystal compound, the liquid crystal compound may lose its liquid crystal properties due to the curing reaction, resulting in increased molecular weight.

[0061] The other liquid crystal layers are preferably layers formed using a composition containing a polymerizable liquid crystal compound. The polymerizable liquid crystal compound is as described above.

[0062] The thickness of the other liquid crystal layers is not particularly limited, but is preferably 10 μm or less, more preferably 0.1 to 5.0 μm, and even more preferably 0.5 to 3.0 μm.

[0063] Other liquid crystal layers include A plates, C plates, and liquid crystal layers in which liquid crystal compounds are twisted and oriented at a twist angle of 180° or less (twisted liquid crystal layers). The definitions and preferred embodiments of A plates and twisted liquid crystal layers are the same as the definitions and preferred embodiments of each layer in the liquid crystal layers. The retardation in the thickness direction of the C plate at a wavelength of 550 nm is not particularly limited, but -120 to -20 nm is preferred and -100 to -30 nm is more preferred in terms of superior effects of the present invention. Also, the retardation in the thickness direction of the C plate at a wavelength of 550 nm is not particularly limited, but 10 to 80 nm is preferred and 20 to 60 nm is more preferred in terms of superior effects of the present invention. Other liquid crystal layers preferably include C plates, twisted liquid crystal layers, or twisted liquid crystal layers and C plates, and more preferably twisted liquid crystal layers and C plates. Taking the optical film shown in Figure 2 as an example, it is preferable that the first liquid crystal layer 24 among the other liquid crystal layers is a twisted liquid crystal layer and the second liquid crystal layer 26 is a C plate.

[0064] The optical film of the present invention preferably has λ / 4 functionality. That is, the optical film of the present invention is preferably used as a λ / 4 plate. One preferred embodiment of the optical film of the present invention having λ / 4 functionality is an optical film with the configuration shown in Figure 2, in which the liquid crystal layer 12 is a negative A plate, the first liquid crystal layer 24 of the other liquid crystal layers 22 is a twisted liquid crystal layer, and the second liquid crystal layer 26 is a C plate. In the above embodiment, it is preferable that the in-plane slow axis on the surface of the first liquid crystal layer 24 on the liquid crystal layer 12 side (negative A plate side) and the in-plane slow axis of the liquid crystal layer 12 are parallel. Note that the "parallelism" between the in-plane slow axis on the surface of the first liquid crystal layer 24 on the liquid crystal layer 12 side (negative A plate side) and the in-plane slow axis of the liquid crystal layer 12 includes a range of error that is permissible in the art to which the present invention belongs. Specifically, it means being 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.

[0065] [Other Components] The optical film of the present invention may have other components besides those described above (liquid crystal layer, alignment layer, adhesion layer, other liquid crystal layers). The optical film of the present invention may further have adjacent layers arranged on the surface opposite to the alignment layer side of the liquid crystal layer. The type of adjacent layer is not particularly limited, but examples include adhesion layers such as adhesive layers and tack layers (hereinafter also referred to as "adhesion layer B"). Adhesive layers and tack layers that can be used as adhesion layer B are the same as the adhesive layers and tack layers described above as adhesion layers, and the preferred embodiments are also the same.

[0066] The optical film of the present invention may include a liquid crystal layer, an alignment layer, an adhesion layer, and a support for supporting other liquid crystal layers. The transmittance of the support is not particularly limited, but for example, the transmittance of the support for light with a wavelength of 550 nm is preferably 50% or more, more preferably 70% or more, and even more preferably 85% or more. There is no particular upper limit, but it is often less than 100%. The thickness of the support is preferably 1 to 1000 μm, more preferably 3 to 250 μm, and even more preferably 5 to 150 μm.

[0067] The support may be single-layered or multi-layered. Examples of single-layered supports include those made of glass, triacetylcellulose, polyethylene terephthalate, polycarbonate, polyvinyl chloride, poly(meth)acrylate, and polyolefin. An example of a multi-layered support is a configuration in which the single-layered supports exemplified above are laminated together.

[0068] [Method for Manufacturing Optical Films] The method for manufacturing optical films according to the present invention is not particularly limited, but it is preferable to have a step X1 of forming a liquid crystal layer on the surface of the alignment layer in a substrate with an alignment layer, and a step X2 after step X1 of peeling the substrate off the substrate with the alignment layer, leaving the alignment layer, and forming an adhesion layer on the surface of the exposed alignment layer. Each step will be described below.

[0069] <Step X1> Step X1 is a step of forming a liquid crystal layer on the surface of the alignment layer in a substrate with an alignment layer. More specifically, Step X1 preferably includes the steps of forming a composition layer of a composition containing a liquid crystal compound containing polymerizable groups on the surface of the alignment layer in a substrate with an alignment layer, applying a heat treatment to the composition layer to orient the liquid crystal compound in the composition layer, and applying a curing treatment to the composition layer in which the liquid crystal compound has been oriented to fix the orientation state of the liquid crystal compound. Each step and each component will be described below.

[0070] (Substrate with orientation layer) The substrate with an orientation layer comprises a substrate and an orientation layer disposed on the surface of the substrate.

[0071] 《Substrate》 The type of substrate is not particularly limited as long as it can be peeled off from the orientation layer, and known materials can be used. Known supports can be used. The substrate is preferably a transparent substrate. A transparent substrate is a substrate with a visible light transmittance (for example, wavelength 380 to 780 nm) of 60% or more, preferably 80% or more, and more preferably 90% or more.

[0072] Examples of substrates include glass substrates and polymer films. Examples of polymer film materials include cellulose polymers; acrylic polymers having acrylic acid ester polymers such as polymethyl methacrylate and lactone ring-containing polymers; thermoplastic norbornene polymers; polycarbonate polymers; polyester polymers such as polyethylene terephthalate and polyethylene naphthalate; styrene polymers such as polystyrene and acrylonitrile styrene copolymers; polyolefin polymers such as polyethylene, polypropylene and ethylene-propylene copolymers; vinyl chloride polymers; amide polymers such as nylon and aromatic polyamides; imide polymers; sulfone polymers; polyethersulfone polymers; polyetheretherketone polymers; polyphenylene sulfide polymers; vinylidene chloride polymers; vinyl alcohol polymers; vinyl butyral polymers; arylate polymers; polyoxymethylene polymers; epoxy polymers; and polymers obtained by mixing these polymers.

[0073] The thickness of the substrate is preferably 5 to 60 μm, more preferably 5 to 45 μm, and even more preferably 5 to 40 μm.

[0074] 《Orientation Layer》 The orientation layer is a layer that has a refractive index lower than that of the in-plane slow phase axis direction of the liquid crystal layer adjacent to it, and has the function of aligning the liquid crystal compounds contained in the composition. The orientation layer is as previously described.

[0075] One example of a method for producing an orientation layer is a method that includes the steps of: applying a composition containing a photo-orientation material and one or more selected from radical polymerizable monomers and inorganic particles having an aromatic ring onto a substrate to form a composition layer; irradiating the composition layer with light to perform a curing treatment; and irradiating the cured composition layer with polarized or unpolarized light to form a photo-orientation film. The composition will be described below.

[0076] The composition includes a photo-aligning material. The definition of the photo-aligning material is as described above. Preferably, the photo-aligning material is a polymer having repeating units having photo-aligning groups, and more preferably, a polymer having repeating units having both photo-aligning groups and eccentric groups. An eccentric group refers to a group that is eccentrically located on the air interface side within a film when a film is formed on a substrate using a compound having an eccentric group. As for the eccentric group, a group containing a silicon atom is preferred in terms of superior effects of the present invention, and a group containing two or more silicon atoms is more preferred. In the case of repeating units having eccentric groups, the eccentric group portion may be removed by various actions such as acid and light. A polymer having repeating units having photo-aligning groups also preferably has repeating units having radical polymerizable groups. Among the radical polymerizable groups, ethylenically unsaturated groups such as (meth)acryloyl groups, vinyl groups, styryl groups, and allyl groups are preferred.

[0077] In a polymer having repeating units having photo-orienting groups, the content of repeating units having photo-orienting groups is preferably 8.0 to 48.0% by mass, and more preferably 18.0 to 38.0% by mass, relative to the total number of repeating units. If the polymer having repeating units having photo-orienting groups also contains repeating units having eccentric groups, the content of repeating units having eccentric groups is preferably 10.0 to 50.0% by mass, and more preferably 20.0 to 40.0% by mass, relative to the total number of repeating units. If the polymer having repeating units having photo-orienting groups also contains repeating units having polymerizable groups, the content of repeating units having polymerizable groups is preferably 22.0 to 62.0% by mass, and more preferably 32.0 to 52.0% by mass, relative to the total number of repeating units.

[0078] The weight-average molecular weight of the polymer having repeating units with photo-orienting groups is preferably 30,000 to 100,000, and more preferably 40,000 to 90,000.

[0079] The amount of photo-aligning material in the composition is preferably 0.1 to 10.0% by mass, and more preferably 1.0 to 5.0% by mass, relative to the total solid content of the composition. The photo-aligning material may be used alone or in combination of two or more types.

[0080] The composition comprises one or more selected from a radical polymerizable monomer having an aromatic ring and inorganic particles. The definition and preferred embodiment of the radical polymerizable monomer having an aromatic ring are as described above. The definition and preferred embodiment of inorganic particles are also as described above.

[0081] In the composition, the content of radical polymerizable monomers having an aromatic ring is preferably 9.0 to 83.0% by mass, more preferably 14.0 to 73.0% by mass, and even more preferably 18.0 to 64.0% by mass, based on the total solid content of the composition.

[0082] In the composition, the content of the radical polymerizable monomer having an aromatic ring is preferably 10.0% by mass or more relative to the total mass of the photo-oriented material. There is no particular upper limit to the content of the radical polymerizable monomer having an aromatic ring, but it is preferably 10,000% by mass or less, and more preferably 5,000% by mass or less, relative to the total mass of the photo-oriented material. In the composition, one type of radical polymerizable monomer having an aromatic ring may be used alone, or two or more types may be used in combination.

[0083] The content of inorganic particles (preferably surface-modified inorganic particles) in the composition is preferably 9.0 to 27.0% by mass, more preferably 11.0 to 23.0% by mass, and even more preferably 14.0 to 18.0% by mass, based on the total solid content of the composition. One type of inorganic particle may be used alone, or two or more types may be used in combination.

[0084] The composition may further contain other radical polymerizable monomers other than the aforementioned aromatic ring-containing radical polymerizable monomers (hereinafter also referred to as "other radical polymerizable monomers"). Other specific examples of radical polymerizable monomers include (meth)acrylic acid diesters of alkylene glycols such as neopentyl glycol acrylate, 1,6-hexanediol (meth)acrylate, and propylene glycol di(meth)acrylate; (meth)acrylic acid diesters of polyoxyalkylene glycols such as triethylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate; (meth)acrylic acid diesters of polyhydric alcohols such as pentaerythritol di(meth)acrylate; (meth)acrylic acid diesters of ethylene oxide or propylene oxide adducts such as 2,2-bis{4-(acryloxydiethoxy)phenyl}propane and 2-2-bis{4-(acryloxypolypropoxy)phenyl}propane; epoxy (meth)acrylates; urethane (meth)acrylates; polyester (meth)acrylates, etc.

[0085] Among other radical polymerizable monomers, esters of polyhydric alcohols and (meth)acrylic acid are preferred, and polyfunctional monomers having three or more (meth)acryloyl groups in one molecule are more preferred. Specific examples of esters of polyhydric alcohols and (meth)acrylic acid include pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethylene oxide (EO) modified trimethylolpropane tri(meth)acrylate, propylene oxide (PO) modified trimethylolpropane tri(meth)acrylate, EO modified phosphate tri(meth)acrylate, and trimethylolethane tri(meth)acrylate. Examples include ditrimethylolpropanetetra(meth)acrylate, dipentaerythritoltetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, pentaerythritol hexa(meth)acrylate, 1,2,3-crohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate, and caprolactone-modified tris(acryloxyethyl) isocyanurate.

[0086] In the composition, the content of other radical polymerizable monomers is preferably 5.0 to 79.0% by mass, more preferably 15.0 to 74.0% by mass, and even more preferably 24.0 to 70.0% by mass, based on the total solid content of the composition. The other radical polymerizable monomers may be used alone or in combination of two or more. When the composition contains other radical polymerizable monomers, the blending mass ratio of other radical polymerizable monomers to radical polymerizable monomers having aromatic rings is preferably 90 / 10 to 20 / 80, more preferably 85 / 15 to 30 / 70, and even more preferably 50 / 50 to 35 / 65. Furthermore, the blending mass ratio of other radical polymerizable monomers to inorganic particles is preferably 90 / 10 to 20 / 80, more preferably 85 / 15 to 30 / 70, and even more preferably 50 / 50 to 35 / 65.

[0087] The composition may contain other components besides those listed above. Examples of other components include polymerization initiators, photoacid generators, and other polymers.

[0088] Methods for applying the above composition to a substrate include, for example, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. After applying the composition to the substrate, the substrate on which the coating film has formed may be dried as needed to remove the solvent.

[0089] Next, the coating film is subjected to a curing treatment to react the polymerization components in the composition layer. The curing treatment method is not particularly limited, but light irradiation treatment is preferred. The type of light used for exposure is not particularly limited, but ultraviolet light is preferred. The irradiation dose used for exposure is not particularly limited, but 10 mJ / cm² is preferred. ２ ~50 J / cm ２ Preferably, 20 mJ / cm ２ ~5J / cm ２ This is more preferable. Furthermore, the polymerization reaction may be carried out under heating conditions to accelerate it.

[0090] The composition layer, which has undergone a curing treatment, is irradiated with polarized or unpolarized light to impart the function of a photo-alignment film to the composition layer. The method and procedure for irradiating with polarized or unpolarized light can be carried out by known methods. One specific example of an irradiation method is to irradiate with ultraviolet light through a polarizer that allows only polarization in a certain direction to pass through. Examples of polarizer types include a wire grid type polarizer having an opening in the shape of a slit, a method of polarization separation using the Brewster angle by stacking multiple quartz plates, and a method of polarization separation using the Brewster angles of vapor-deposited multilayer films with different refractive indices.

[0091] Another example of a method for producing an orientation layer is a method comprising the steps of: applying a composition containing a polymer having repeating units having mesogenic groups and one or more selected from a radical polymerizable monomer having an aromatic ring and inorganic particles onto a substrate to form a composition layer; and rubbing the composition layer. The composition used in this production method is the same as that in the example of the method for producing an orientation layer described above, except that the photo-orientation material of the composition is changed to a polymer having repeating units having mesogenic groups, and the preferred embodiments are also the same. The polymer having repeating units having mesogenic groups may further contain repeating units having eccentric groups. Examples of repeating units having eccentric groups are the same as those having repeating units having eccentric groups that can be contained in the photo-orientation material, and the preferred embodiments are also the same.

[0092] In a polymer containing repeating units having mesogenic groups, the content of repeating units having mesogenic groups is preferably 40.0 to 80.0% by mass, and more preferably 50.0 to 70.0% by mass, relative to the total number of repeating units. If the polymer containing repeating units having mesogenic groups also contains repeating units having eccentric groups, the content of repeating units having eccentric groups is preferably 20.0 to 60.0% by mass, and more preferably 30.0 to 50.0% by mass, relative to the total number of repeating units. The weight-average molecular weight of the polymer containing repeating units having mesogenic groups is preferably 8,000 to 50,000, and more preferably 12,000 to 30,000.

[0093] Methods for applying the above composition to a substrate include, for example, wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. After applying the composition to the substrate, the substrate on which the coating film has formed may be dried as needed to remove the solvent.

[0094] Next, a curing treatment is performed on the coating film to react the polymerization components in the composition layer. The method of the curing treatment is not particularly limited, and a light irradiation treatment is preferred. The type of light during exposure is not particularly limited, but ultraviolet light is preferred. The irradiation amount during exposure is not particularly limited, but 10 mJ / cm ２ to 50 J / cm ２ is preferred, and 20 mJ / cm ２ to 5 J / cm ２ is more preferred. Further, in order to promote the polymerization reaction, it may be carried out under heating conditions.

[0095] Next, a rubbing treatment is performed on the surface of the composition layer subjected to the curing treatment. The rubbing treatment can be carried out by a known method. For example, a method of rubbing the surface of the composition layer subjected to the curing treatment several times in a certain direction with paper or cloth can be mentioned.

[0096] (Procedure of Step X1) In Step X1, it is preferable to form a composition layer containing a liquid crystal compound having a polymerizable group on the surface of the alignment layer of the substrate with an alignment layer. The form of the liquid crystal compound having a polymerizable group is as described above. The composition layer may contain other components in addition to the liquid crystal compound having a polymerizable group. Examples of other components include a chiral agent, a polymerization initiator, a surfactant, and an alignment control agent (for example, a vertical alignment agent and a horizontal alignment agent).

[0097] As one aspect of a specific procedure for forming a composition layer containing a liquid crystal compound having a polymerizable group, a method of applying a composition containing a liquid crystal compound containing a polymerizable group on the surface of the alignment layer can be mentioned. Examples of the method of applying the composition on the alignment layer include a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die coating method. After applying the composition on the alignment layer, if necessary, a drying treatment may be performed on the substrate on which the coating film is formed to remove the solvent.

[0098] In step X1, it is preferable to orient the liquid crystal compound in the composition layer. The method for orienting the liquid crystal compound in the composition layer (coating film) (orientation treatment) is not particularly limited, and examples include heating the coating film and drying the coating film at room temperature. In the case of thermotropic liquid crystal compounds, the liquid crystal phase formed by the orientation treatment can generally be transferred by changing the temperature. In the case of lyotropic liquid crystal compounds, the transfer 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 150°C, and the heating time is preferably 10 seconds to 5 minutes.

[0099] In step X1, it is preferable to then perform a curing treatment on the coating film in which the liquid crystal compound is oriented to form a liquid crystal layer. The curing treatment method is not particularly limited, and examples include light irradiation treatment and heat treatment, with light irradiation treatment being more preferable. The type of light used for exposure is not particularly limited, but ultraviolet light is preferred. The amount of irradiation used for exposure is not particularly limited, but 10 mJ / cm² is preferred. ２ ~50 J / cm ２ Preferably, 20 mJ / cm ２ ~5J / cm ２ This is more preferable. Furthermore, the polymerization reaction may be carried out under heating conditions to accelerate it.

[0100] <Step X2> Step X2 is a step in which, after step X1, the substrate is peeled off from the substrate with the alignment layer, leaving the alignment layer intact, and an adhesion layer (adhesion layer A) is formed on the surface of the exposed alignment layer. Step X2 may also be a step in which the exposed alignment layer is bonded to other components (for example, other liquid crystal layers, etc.) via an adhesive or tack, and curing treatment is performed by irradiation with active energy rays or heating as necessary. The adhesives or tacks that can be used to form the adhesion layer are as described above.

[0101] <Step X3> When the optical film has another liquid crystal layer on the surface opposite to the alignment layer side of the adhesion layer, the method for manufacturing the optical film of the present invention preferably further includes a step X3 after step X2, in which another liquid crystal layer is formed on the surface opposite to the alignment layer side of the adhesion layer. Step X3 may be a method of laminating the other liquid crystal layer formed on the substrate to the surface of the laminate obtained in step X2 that is opposite to the alignment layer side of the adhesion layer, or it may be a method of directly forming the other liquid crystal layer on the surface of the laminate obtained in step X2 that is opposite to the alignment layer side of the adhesion layer by means such as a coating method. Step X3 can be carried out by known methods.

[0102] [Polarizing Plate] The polarizing plate of the present invention is a polarizing plate comprising the optical film of the present invention and a polarizer. The polarizing plate may contain multiple optical films of the present invention. The configuration of the optical film is as described above. Figure 3 shows an example of the polarizing plate of the present invention. The polarizing plate 30 shown in Figure 3 has the optical film 20 shown in Figure 2 on one side of the polarizer 32 and a protective film 34 on the other side of the polarizer 32. The optical film 20 is bonded to the surface of the polarizer 32 via an adhesive layer (not shown). The protective film 34 is an optional component and may not be provided. The adhesive layer (not shown) can be an adhesive layer or a tack layer as described in the upper section, and the preferred embodiment is the same. The components (polarizer, protective film, adhesive layer) of the polarizing plate of the present invention will be described in detail below.

[0103] [Polarizer] A polarizer can be any material that has the function of converting natural light into a specific linearly polarized light, for example, an absorptive polarizer. There are no particular restrictions on the type of polarizer, and commonly used polarizers can be used, for example, iodine-based polarizers, dye-based polarizers using dichroic substances, and polyene-based polarizers. Iodine-based polarizers and dye-based polarizers are generally made by adsorbing iodine or a dichroic dye onto polyvinyl alcohol and stretching it. A protective film may be placed on one or both sides of the polarizer.

[0104] The polarizer is preferably formed using a composition containing a dichroic substance and a liquid crystal compound having polymerizable groups. The dichroic substance is not particularly limited and can be a visible light absorbing substance (dichroic dye), a light emitting substance (fluorescent substance, phosphorescent substance), an ultraviolet absorbing substance, an infrared absorbing substance, a nonlinear optical substance, a carbon nanotube, or an inorganic substance (e.g., a quantum rod). In the present invention, two or more dichroic substances may be used in combination. For example, from the viewpoint of making the polarizer closer to black, it is preferable to use in combination at least one dye compound having a maximum absorption wavelength in the range of 370 to 550 nm and at least one dye compound having a maximum absorption wavelength in the range of 500 to 700 nm.

[0105] The polarizing plate of the present invention may have other functional layers in addition to the above-mentioned components. Examples of other functional layers include an adhesive layer, a stress relaxation layer, a planarizing layer, an anti-reflective layer, a refractive index adjustment layer, and an ultraviolet absorption layer.

[0106] The polarizer can be used as a circular polarizer when the optical film of the present invention has a λ / 4 function. When the polarizer has the configuration of the polarizer 30 shown in Figure 3, and the liquid crystal layer 12 is a negative A plate, the first liquid crystal layer 22 of the other liquid crystal layers 22 is a twisted liquid crystal layer, and the second liquid crystal layer is a C plate, the absolute value of the angle between the in-plane slow axis of the liquid crystal layer 12 (negative A plate) and the absorption axis of the polarizer 32 is preferably 50 to 85°, and more preferably 65 to 75°, in terms of suitably applying the optical film to a circular polarizer or the like. Note that the "absorption axis" of the polarizer means the direction of the highest absorbance.

[0107] [Protective Film] Examples of materials for the protective film include cellulose acylate films (e.g., cellulose triacetate film, cellulose diacetate film, cellulose acetate butyrate film, and cellulose acetate propionate film, etc.), polyacrylic resin films such as polymethyl methacrylate, polyolefins such as polyethylene and polypropylene, polyester resin films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films, polyurethane resin films, polyester films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyetherketone films, (meth)acrylonitrile films, polyolefins, and polymers having an alicyclic structure (norbornene resin (Arton: trade name, manufactured by JSR Corporation, amorphous polyolefin (Zeonex: trade name, manufactured by Nippon Zeon Co., Ltd.))), with cellulose acylate films being preferred.

[0108] [Adhesion Layer] The polarizing plate of the present invention may have an adhesive layer as an adhesion layer. For example, there may be an adhesive layer between the film of the present invention and another liquid crystal layer, and an adhesive layer between the polarizer and the polarizing plate of the present invention. Examples of adhesives included in the adhesive layer include acrylic adhesives, epoxy adhesives, rubber adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone adhesives, polyacrylamide adhesives, and cellulose adhesives. Among these, acrylic adhesives (pressure-sensitive adhesives) are preferred in terms of their excellent transparency, weather resistance, and heat resistance. For adhesives, refer to paragraphs

[0071] to

[0084] of Japanese Patent Application Publication No. 2018-060014, and the contents of these paragraphs are incorporated herein.

[0109] <Applications> The optical film and polarizing plate of the present invention can be applied to various applications, for example, to display devices. Examples of display devices include liquid crystal displays, organic electroluminescent (EL) displays, micro-LED displays, head-up displays, and head-mounted displays. The display device of the present invention preferably includes a display element and the optical film or polarizing plate of the present invention. Liquid crystal display elements and organic EL display elements are preferred as the display element.

[0110] The present invention will be described in more detail below based on examples. The materials, amounts used, proportions, processing content, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the examples shown below.

[0111] [Example 1] [Preparation of Cellulose Acylate Film (Substrate)] <Preparation of Core Layer Cellulose Acylate Dope> The following components were added to a mixing tank and stirred to dissolve each component, and a cellulose acetate solution to be used as the core layer cellulose acylate dope was prepared. -------------------------------------------------- Core Layer Cellulose Acylate Dope -------------------------------------------------- ・Cellulose acetate with acetyl substitution degree of 2.88 100 parts by mass ・Polyester compound B described in the example of Japanese Patent Application Publication No. 2015-227955 8 parts by mass ・Compound G below 4 parts by mass ・Methylene chloride (first solvent) 430 parts by mass ・Methanol (second solvent) 64 parts by mass --------------------------------------------------

[0112] 《Compound G》

[0113]

[0114] <Preparation of outer layer cellulose acylate dope> A cellulose acetate solution to be used as the outer layer cellulose acylate dope was prepared by adding 10 parts by mass of the following matting agent solution to 90 parts by mass of the above core layer cellulose acylate dope. -------------------------------------------------- Matting agent solution -------------------------------------------------- Silica particles with an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass Methylene chloride (first solvent) 76 parts by mass Methanol (second solvent) 11 parts by mass The above core layer cellulose acylate dope 1 part by mass --------------------------------------------------

[0115] The core layer cellulose acylate dope and the outer layer cellulose acylate dope were filtered using filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm. Then, the core layer cellulose acylate dope and the outer layer cellulose acylate dope on both sides were simultaneously cast into a drum at 20°C from the casting port (band casting machine). The film was peeled off with a solvent content of approximately 20% by mass, and both ends in the width direction of the film were fixed with tenter clips. The film was then dried while being stretched transversely at a stretching ratio of 1.1 times. After that, the obtained film was further dried by being transported between rolls in a heat treatment device to produce a film with a thickness of 40 μm, which was designated as cellulose acylate film 1. The in-plane retardation of the obtained cellulose acylate film 1 at a wavelength of 550 nm was 0 nm. The obtained cellulose acylate film 1 was used as a substrate.

[0116] [Fabrication of Laminate LC-1] <Formation of Photo-Orientation Layer PA-1> On the cellulose acylate film prepared in the upper section, a photo-orientation layer forming solution PA-1 with the following composition was applied using a Gieser coating machine to form a composition layer. Then, holding both ends of the film, a cooling plate (9°C) was placed on the side of the film where the coating was formed, at a distance of 5 mm from the film, and a heater (75°C) was placed on the opposite side of the film where the coating was formed, at a distance of 5 mm from the film, and the film was dried for 2 minutes. Next, it was heated with hot air at 60°C for 1 minute, and while purging with nitrogen to maintain an atmosphere with an oxygen concentration of 100 ppm by volume or less, an irradiation dose of 100 mJ / cm was applied using a 365 nm UV-LED. ２ The material was irradiated with ultraviolet light. Then, a precursor layer was formed by annealing with hot air at 120°C for 1 minute. The resulting precursor layer was then exposed to UV light (ultra-high pressure mercury lamp; UL750; manufactured by HOYA) at room temperature, passing through a wire grid polarizer at a rate of 7.9 mJ / cm². ２ The photo-alignment layer PA-1 was formed by irradiation with a wavelength of 313 nm. At this time, the transmission axis of the wire grid polarizer was set at an angle of 14° with respect to the longitudinal direction of the film. The thickness of the formed photo-alignment layer PA-1 was 0.5 μm. Furthermore, as will be described later, the obtained photo-alignment layer PA-1 was optically isotropic, and its refractive index na (in-plane mean refractive index) was 1.58.

[0117] -------------------------------------------------- Photo-oriented layer forming composition (PA-1) -------------------------------------------------- Monomer M-1 64 parts by mass Monomer M-2 27 parts by mass Polymerization initiator S-1 (oxime type) 5 parts by mass Photoacid generator D-1 3 parts by mass Polymer A-1 2 parts by mass Photo-oriented polymer P-1 2 parts by mass Methyl ethyl ketone 25 parts by mass Methyl isobutyl ketone 375 parts by mass --------------------------------------------------

[0118] Monomer M-1: Acrylate monomer having a fluorene moiety (9,9-bis[4-(2-acryloyloxyethoxy)phenyl]fluorene)

[0119]

[0120] Monomer M-2: Acrylate monomer (product name "Light Acrylate PE-4A", manufactured by Kyoei Chemical Co., Ltd., pentaerythritol tetraacrylate)

[0121] Polymerization initiator S-1

[0122]

[0123] Photoacid Generator D-1

[0124]

[0125] 《Polymer A-1》 In the following formula, the numerical value in the repeating unit represents the content (mass %) relative to the total number of repeating units. The weight-average molecular weight was 30,000.

[0126]

[0127] 《Photo-Oriented Polymer P-1》 In the following formula, a, b, and c represent the content (mass%) of each repeating unit relative to the total number of repeating units, where a was 30% by mass, b was 28% by mass, and c was 42% by mass. The weight-average molecular weight was 69,000. Me represents a methyl group.

[0128]

[0129] <Formation of Liquid Crystal Layer LC-1> An optical anisotropic layer-forming composition (1a) containing a disc-shaped liquid crystal compound of the following composition was applied to the photo-alignment layer PA-1 prepared above using a Gieser coating machine to form a composition layer. Subsequently, the obtained composition layer was heated with hot air for 2 minutes to 90°C to dry the solvent and mature the alignment of the disc-shaped liquid crystal compound. Then, the obtained composition layer was subjected to N24 at 80°C. ２ UV irradiation under purging (100 mJ / cm²) ２ (Light source: metal halide, measurement wavelength: 365 nm) was used to fix the orientation of the liquid crystal compound and form a liquid crystal layer LC-1 (hereinafter also referred to as "optical anisotropy layer LC-1"), thereby obtaining a film. The thickness of the liquid crystal layer LC-1 was 1.7 μm. The in-plane retardation at a wavelength of 550 nm was 168 nm. The average inclination angle of the disc surface of the disc-shaped liquid crystal compound with respect to the film surface was 90°, confirming that it was oriented perpendicular to the film surface. The angle between the in-plane slow axis of the liquid crystal layer LC-1 and the longitudinal direction of the film was 76°. Furthermore, when the orientation layer surface on the side in contact with the liquid crystal layer LC-1 was examined using the method described above, the presence of the photo-oriented polymer P-1 was confirmed.

[0130] -------------------------------------------------- Composition for forming an optically anisotropic layer (1a) -------------------------------------------------- ・Disc-shaped liquid crystal compound 1 below 80 parts by mass ・Disc-shaped liquid crystal compound 2 below 20 parts by mass ・Orientation film interface orientation agent 1 below 2.0 parts by mass ・Silicon-containing compound A below 0.20 parts by mass ・Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 5 parts by mass ・Photopolymerization initiator (1-(biphenyl-4-yl)-2-methyl-2-morpholinopropan-1-one) 4 parts by mass ・Methyl ethyl ketone 250 parts by mass --------------------------------------------------

[0131] Disc-shaped liquid crystal compound 1

[0132] Disc-shaped liquid crystal compound 2

[0133] 《Orientation film interface orientation agent 1》

[0134] 《Silicon-containing compound A》 In the following formula, a, b, c, and d represent the content (mol%) of each repeating unit relative to the total repeating units, where a is 78 mol%, b is 10 mol%, c is 11 mol%, and d is 1 mol%. The weight-average molecular weight was 13,500.

[0135]

[0136] Following the procedure described above, a long laminate LC-1 was fabricated in which a photo-alignment layer PA-1 and a liquid crystal layer LC-1 were arranged in that order on a long cellulose acylate film.

[0137] [Fabrication of Laminate LC-2] <Formation of Optical Anisotropic Layer (1c)> An optical anisotropic layer-forming composition (1c) containing a rod-shaped liquid crystal compound of the following composition was applied to the cellulose acylate film prepared in the upper section using a Gieser coating machine to form a composition layer. Then, holding both ends of the film, a cooling plate (9°C) was placed on the side of the film where the coating was formed, at a distance of 5 mm from the film, and a heater (75°C) was placed on the opposite side of the film where the coating was formed, at a distance of 5 mm from the film, and the film was dried for 2 minutes. Next, it was heated with hot air at 60°C for 1 minute, and while purging with nitrogen to maintain an atmosphere with an oxygen concentration of 100 ppm by volume or less, an irradiation dose of 100 mJ / cm was applied using a 365 nm UV-LED. ２ The material was irradiated with ultraviolet light. Then, a precursor layer was formed by annealing with hot air at 120°C for 1 minute. The resulting precursor layer was then exposed to UV light (ultra-high pressure mercury lamp; UL750; manufactured by HOYA) at room temperature, passing through a wire grid polarizer, at a rate of 7.9 mJ / cm². ２ By irradiating with a wavelength of 313 nm, a composition layer with orientation control capability was formed on the surface. The thickness of the formed composition layer was 0.5 μm. The in-plane retardation Re at a wavelength of 550 nm was 0 nm, and the retardation Rth in the thickness direction at a wavelength of 550 nm was -78 nm. The average inclination angle of the rod-shaped liquid crystal compound with respect to the film surface in the direction of the long axis was 90°, confirming that it was oriented perpendicular to the film surface. In this way, an optically anisotropic layer (1c) was formed.

[0138] -------------------------------------------------- Composition for forming an optically anisotropic layer (1c) -------------------------------------------------- The following rod-shaped liquid crystal compound (A) 100 parts by mass Polymerizable monomer (A-400, manufactured by Shin Nakamura Chemical Industry Co., Ltd.) 4 parts by mass Polymerization initiator S-1 (oxime type) 5 parts by mass Photoacid generator D-1 3 parts by mass Polymer A-2 2 parts by mass Vertical alignment agent S01 2 parts by mass Photo-aligning polymer P-1 2 parts by mass Methyl ethyl ketone 42 parts by mass Methyl isobutyl ketone 628 parts by mass --------------------------------------------------

[0139] 《Rod-shaped liquid crystal compound (A)》 Rod-shaped liquid crystal compound (A) is a mixture of the following compounds.

[0140] In the formula for Polymer A-2, the numerical values ​​in each repeating unit represent the content (mass%) relative to the total number of repeating units. The weight-average molecular weight was 60,000.

[0141]

[0142] Vertical Orientation Agent S01

[0143] <Formation of Optical Anisotropic Layer (1b)> Next, an optical anisotropic layer-forming composition (1b) containing a rod-shaped liquid crystal compound of the following composition was applied onto the optical anisotropic layer (1c) prepared above using a Gieser coating machine, and heated with 80°C hot air for 60 seconds. Subsequently, the resulting composition layer was irradiated with UV light at 80°C (500 mJ / cm²). ２The orientation of the liquid crystal compound was fixed by performing the following procedure to form 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 is set to 0° (the longitudinal direction is 90°), the orientation axis angle of the liquid crystal compound, when viewed from the optically anisotropic layer (1b) side, was 14° on the air side and 95° on the side in contact with the optically anisotropic layer (1c). The orientation axis angle of the liquid crystal compound contained in the optically anisotropic layer is expressed by observing the substrate from the surface side of the optically anisotropic layer, with the width direction of the substrate as the reference 0°, and clockwise (right-hand rotation) being negative and counterclockwise (left-hand rotation) being positive. Furthermore, the twist angle of the liquid crystal compound is expressed by observing the substrate from the surface side of the optically anisotropic layer, with the orientation axis direction of the liquid crystal compound on the surface side (front side) as the reference, and a clockwise (rightward) orientation axis direction of the liquid crystal compound on the substrate side (back side) being considered negative, and a counterclockwise (leftward) orientation being considered positive.

[0144] -------------------------------------------------- Composition for forming an optically anisotropic layer (1b) -------------------------------------------------- The above rod-shaped liquid crystal compound (A) 70 parts by mass The following rod-shaped liquid crystal compound (B) 30 parts by mass Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass Photopolymerization initiator (Irgacure 819, manufactured by BASF) 3 parts by mass The following left-hand torsion chiral agent (L1) 0.5 parts by mass The following silicon-containing compound D 0.2 parts by mass Methyl isobutyl ketone 126 parts by mass Ethyl propionate 126 parts by mass --------------------------------------------------

[0145] <<Rod-shaped liquid crystal compound (B)>>

[0146] Left-hand twist chiral agent (L1) In the following formula, Bu represents a butyl group.

[0147] In the formula for silicon-containing compound D, the numerical values ​​in each repeating unit represent the content (mass %) relative to the total number of repeating units. The weight-average molecular weight was 18,000.

[0148] Following the above procedure, a long laminate LC-2 was fabricated in which a liquid crystal layer LC-2, composed of an optically anisotropic layer (1c) and an optically anisotropic layer (1b), was directly laminated onto a long cellulose acylate film.

[0149] [Preparation of Polarizing Plate POL1] <Preparation of Linear Polarizing Plate 1> The surface of a cellulose triacetate film TJ25 (manufactured by Fujifilm Corporation: 25 μm thick) support was subjected to alkali saponification treatment. Specifically, the support was immersed in a 1.5 N sodium hydroxide aqueous solution at 55°C for 2 minutes, then washed in a water bath at room temperature, and further neutralized with 0.1 N sulfuric acid at 30°C. After neutralization, the support was washed in a water bath at room temperature, and further dried with hot air at 100°C to obtain a polarizer protective film. A roll-shaped polyvinyl alcohol (PVA) film with a thickness of 60 μm was continuously stretched in the longitudinal direction in an iodine aqueous solution and dried to obtain a polarizer with a thickness of 13 μm. The luminous efficiency correction single transmittance of the polarizer was 43%. At this time, the absorption axis direction and the longitudinal direction of the polarizer coincided. The polarizer protective film was attached to one side of the above polarizer using the PVA adhesive described below to prepare a linear polarizing plate 1.

[0150] (Preparation of PVA adhesive) A PVA adhesive was prepared by dissolving 100 parts by mass of a polyvinyl alcohol resin having an acetoacetyl group (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, degree of acetoacetylation: 5 mol%) and 20 parts by mass of methylolmelamine in pure water at a temperature of 30°C, and adjusting the solid content concentration to 3.7% by mass as an aqueous solution.

[0151] <Fabrication of Polarizing Plate POL1> The liquid crystal layer side of the laminate LC-1 fabricated in the upper section and the surface of the polarizer of the long linear polarizing plate 1 (the side opposite the polarizer protective film) were continuously bonded using a 2 μm thick UV-curing adhesive. The cellulose acylate film of the laminate LC-1 was peeled off to expose the photo-alignment layer PA-1. The surface of the exposed photo-alignment layer PA-1 and the surface of the optical anisotropy layer (1b) side of the laminate LC-2 were continuously bonded using a 2 μm thick UV-curing adhesive. Polarizing plate POL1 was thus fabricated. Polarizing plate POL1 consists of a polarizer protective film, polarizer, adhesion layer B (adhesive layer), liquid crystal layer LC-1, photo-alignment layer PA-1, adhesion layer A (adhesive layer), optical anisotropy layer (1b), and optical anisotropy layer (1c) laminated in this order, and the angle between the absorption axis of the polarizer and the slow axis of the liquid crystal layer LC-1 was 76°. Furthermore, with the width direction as the reference 0°, the orientation axis angle of the liquid crystal compound on the optical anisotropy layer (1b) side of the liquid crystal layer LC-2 was 14°, which coincided with the slow phase axis direction of the liquid crystal layer LC-1.

[0152] Furthermore, the optically anisotropic layer (1c) is a positive C plate, the optically anisotropic layer (1b) is a twisted liquid crystal layer in which the liquid crystal compound is in a twisted orientation along the film thickness direction, and the liquid crystal layer LC-1 is a negative A plate.

[0153] [Measurement and Evaluation] [Measurement of the refractive index of the liquid crystal layer in the in-plane slow axis direction and the refractive index of the alignment layer] The refractive index of the liquid crystal layer in the in-plane slow axis direction and the refractive index of the alignment layer were measured by the method described above. The values ​​of the refractive index of the liquid crystal layer in the in-plane slow axis direction and the refractive index of the alignment layer are shown in Table 1. Note that the ny of the liquid crystal layer in the optical films of Examples 1 to 7 and Comparative Examples 1 to 2 is 1.53 in all cases.

[0154] [Measurement of the refractive index of adhesion layer A and adhesion layer B] The refractive index of adhesion layer A was measured by the method described above. The refractive index of adhesion layer A measured by the above method is 1.53. In addition, the refractive index of adhesion layer B, which is placed on the laminated surface with the polarizer, was measured using the same procedure as for measuring the refractive index of adhesion layer A. The refractive index of adhesion layer B measured by the above method is 1.53. Note that the refractive index of adhesion layer A and adhesion layer B are the refractive index of the UV-curable adhesive after curing.

[0155] [Confirmation that the orientation layer is optically isotropic] Re(λ) and Rth(λ) were measured before and after lamination of the orientation layer on the substrate, and the absolute values ​​of the difference between Re(λ) and Rth(λ) before and after lamination were calculated, confirming that each value was 5 nm or less.

[0156] [Evaluation of Liquid Crystal Alignment] The fabricated laminate LC-1 was sandwiched between two crossed nicol polarizers and positioned 5° away from the extinction point. The presence or absence of visible irregularities was determined when observed on a light box. In addition, if no irregularities were visible on the light box, the material was observed using a polarizing microscope at a 5° offset from the extinction point. The following criteria were used for evaluation. The results are shown in Table 1 below. [Evaluation Criteria] A: No irregularities are visible on the light box, and there is no disturbance in the liquid crystal director. B: No irregularities are visible on the light box, and a very slight disturbance in the liquid crystal director is observed. C: No irregularities are visible on the light box, and disturbance in the liquid crystal director is observed throughout. D: Irregularities are visible on the light box.

[0157] [Evaluation of In-Plane Color Unevenness] A laminated sample was obtained by laminating the fabricated polarizing plate POL1 in the following order: AR-coated glass / pressure-sensitive adhesive (refractive index 1.47) / polarizing plate POL1 / pressure-sensitive adhesive (refractive index 1.47) / black acrylic plate (Acrylite L502 black, manufactured by Mitsubishi Chemical Corporation). At this time, the AR-coated glass side was made on the surface of the polarizer protective film side of the polarizing plate POL1. The laminate obtained above, including the black acrylic plate, corresponds to a model of an embodiment in which the optical film of the present invention is placed on an image display element and black is displayed. Therefore, if the predetermined effect is obtained in the above laminate, the same effect can be obtained when the film of the present invention is applied to an image display element. Under a rod-shaped fluorescent lamp (FPL-27EX-N), the sample was set at an azimuth angle in which the long axis of the rod-shaped fluorescent lamp and the longitudinal direction of the polarizing plate POL1 are perpendicular, via a diffuser plate, and the in-plane color was observed from an extreme angle of 30 to 40°. When setting up the samples, the AR-coated glass was positioned so that it faced the fluorescent lamp. This allowed us to evaluate the in-plane color uniformity when viewed from an oblique angle. The evaluation criteria were as follows:

[0158] A: No color difference is visible on the surface, or only a very slight difference is visible. (Acceptable) B: A color difference is visible on the surface, but there is no problem in use. (Acceptable) C: A color difference is visible on the surface and is unacceptable. D: A clearly strong color difference is visible on the surface and is unacceptable.

[0159] [Example 2] Laminate LC-2 and polarizer POL2 were prepared using the same procedure as for laminate LC-1 and polarizer POL1 in Example 1, except that monomer M-1 in the photo-alignment layer forming composition (PA-1) was replaced with monomer M-3 (dinaphtho[2,1-b:1',2'-d]thiophene-2,12-diyldiacrylate), and the mixing ratio of monomer M-2 and monomer M-3 was changed to the values ​​shown in Table 1. Various evaluations were also performed using the same procedure as in Example 1.

[0160]

[0161] [Example 3] Laminate LC-3 and polarizer POL3 are manufactured using the same manufacturing procedure as in Example 1, except that monomer M-1 in the photo-alignment layer forming composition (PA-1) is replaced with monomer M-3, and the mixing ratio of monomer M-2 and monomer M-3 is changed to the values ​​shown in Table 1. Various evaluations are also performed using the same procedure as in Example 1.

[0162] [Example 4] Laminate LC-4 and polarizer POL4 were prepared using the same procedure as for laminate LC-1 and polarizer POL1 in Example 1, except that monomer M-1 in the photo-alignment layer forming composition (PA-1) was replaced with surface-modified zirconia particles, and the mixing ratio of monomer M-2 and surface-modified zirconia particles was changed to the values ​​shown in Table 1. Various evaluations were also performed using the same procedure as in Example 1. <Preparation of Zirconium Oxide Particle Dispersion Z> 20 parts by mass of zirconia particle powder were mixed with 70 parts by mass of methyl isobutyl ketone as a dispersion medium and 10 parts by mass of methacryloxypropyltrimethoxysilane, a silane coupling agent containing an acrylic group, as a surface modifier, thereby modifying the surface of the zirconia particles with the surface modifier. A dispersion treatment was then performed to prepare a transparent zirconia dispersion (Z) with a solid content of 30% by mass.

[0163] [Example 5] Laminate LC-5 and polarizer POL5 were prepared using the same manufacturing procedure as in Example 1, except that monomer M-2 (light acrylate PE-4A) in the photo-alignment layer forming composition (PA-1) was replaced with monomer M-4 (product name "light acrylate DCP-A", manufactured by Kyoei Chemical Co., Ltd.), monomer M-1 was replaced with monomer M-3, and the mixing ratio of monomer M-3 and monomer M-4 was changed to the value shown in Table 1. Various evaluations were also performed using the same procedure as in Example 1.

[0164] [Example 6] Laminate LC-6 and polarizer POL-6 were manufactured using the same manufacturing procedure as in Example 1, except that the orientation polymer P-1 in the photo-alignment layer forming composition (PA-1) was replaced with orientation polymer P-2 (a polymer with the structure shown below), the amount added was 0.2% by mass relative to the total solid content of the orientation layer, and the method of manufacturing the orientation layer was changed from polarized light exposure to rubbing treatment. Various evaluations were then performed using the same procedure as in Example 1.

[0165] 《Oriented Polymer P-2》 In the formula below, the repeating units on the left accounted for 40% by mass of the total repeating units, and the repeating units on the right accounted for 60% by mass of the total repeating units. The weight-average molecular weight was 18,000.

[0166]

[0167] [Example 7] Laminate LC-7 and polarizer POL7 were manufactured using the same manufacturing procedure as in Example 1, except that monomer M-1 in the photo-alignment layer forming composition (PA-1) was replaced with monomer M-3, and the mixing ratio of monomer M-2 and monomer M-3 was changed to the values ​​shown in Table 1. Various evaluations were also performed using the same procedure as in Example 1.

[0168] [Comparative Example 1] Laminate LC-H1 and polarizer POL-H1 were prepared using the same manufacturing procedure as for laminate LC-1 and polarizer POL-H1 in Example 1, except that monomer M-1 in the photo-alignment layer forming composition (PA-1) was changed to monomer M-3, and the mixing ratio of monomer M-2 and monomer M-3 was changed to the values ​​shown in Table 1. Various evaluations were also performed using the same procedure as in Example 1.

[0169] [Comparative Example 2] Laminate LC-H2 and polarizer POL-H2 were prepared using the same procedure as for laminate LC-1 and polarizer POL-H2 in Example 1, except that monomer M-1 in the photo-alignment layer forming composition (PA-1) was not used, the amount of monomer M-1 was changed to 91 parts by mass, and aligning polymer P-1 was changed to aligning polymer P-3 (a polymer with the structure described below). Various evaluations were also performed using the same procedure as in Example 1.

[0170] 《Oriented Polymer P-3》 In the formula below, the numerical value accompanying each repeating unit represents the content (mass%) of that repeating unit relative to the total number of repeating units. The weight-average molecular weight was 50,000.

[0171]

[0172] Table 1 is shown below. In the table below, the "mass ratio" shown in the columns for "Monomer A" and "Monomer B or inorganic particles" refers to the mass ratio of "Monomer A" to "Monomer B or inorganic particles". Note that Monomer B is a radical polymerizable monomer having an aromatic ring. Monomer A is a radical polymerizable monomer that does not fall under the category of a radical polymerizable monomer having an aromatic ring. In the table, the "refractive index" column in the "adhesion layer" column represents the refractive index of adhesion layer A, the "refractive index na" column in the "orientation layer" column represents the in-plane average refractive index of the orientation layer, and the "refractive index nx" column in the "liquid crystal layer" column represents the refractive index of the liquid crystal layer in the in-plane slow axis direction. Furthermore, the orientation layers in each optical film of the examples and comparative examples all exhibit optical isotropy.

[0173]

[0174] From the results in Table 1, it is clear that when the alignment layer placed between the liquid crystal layer and the adhesion layer in the optical film of the present invention is a photo-alignment layer, the liquid crystal alignment is superior. Furthermore, in the optical film of the present invention, it is clear that when the absolute value of the difference between the refractive index in the in-plane slow axis direction of the liquid crystal layer (refractive index nx) and the in-plane average refractive index of the alignment layer (refractive index na) is 0.04 or less, in-plane color unevenness is less likely to occur.

[0175] 10, 20 Optical film 12 Liquid crystal layer 14 Alignment layer 16 Adhesion layer 22 Other liquid crystal layers 24 First liquid crystal layer 26 Second liquid crystal layer 30 Polarizing plate 32 Polarizer 34 Protective film

Claims

1. An optical film comprising a liquid crystal layer, an alignment layer adjacent to at least one face of the liquid crystal layer, and an adhesion layer adjacent to the alignment layer, wherein the adhesion layer is an adhesive layer or a tack layer, the alignment layer is optically isotropic, the refractive index of the liquid crystal layer in the in-plane slow axis direction is greater than the refractive index of the alignment layer, the refractive index of the alignment layer is greater than the refractive index of the adhesion layer, and the absolute value of the difference between the refractive index of the liquid crystal layer in the in-plane slow axis direction and the refractive index of the alignment layer is 0.09 or less.

2. The optical film according to claim 1, wherein the orientation layer comprises a polymer having repeating units derived from a radical polymerizable monomer having an aromatic ring, or inorganic particles.

3. The optical film according to claim 2, wherein the radical polymerizable monomer has at least one skeleton selected from a fluorene skeleton, a dinaphthothiophene skeleton, a naphthalene skeleton, anthracene skeleton, a benzotriazole skeleton, a triazine skeleton, a benzophenone skeleton, a merocyanine skeleton, a benzoxazole skeleton, a benzothiol skeleton, a triphenylene skeleton, a bisphenol skeleton, and a tran skeleton.

4. The optical film according to claim 2, wherein the inorganic particles include atoms selected from the group consisting of zirconium and titanium.

5. The optical film according to claim 1 or 2, wherein the orientation layer comprises a photo-orientation material.

6. The optical film according to claim 2, wherein the orientation layer is a layer formed using a composition comprising a photo-orientation material and the radical polymerizable monomer, and the content of the radical polymerizable monomer is 10.0% by mass or more with respect to the total mass of the photo-orientation material.

7. The optical film according to claim 5, wherein the photo-aligning material is a compound having a photo-aligning group.

8. The optical film according to claim 1 or 2, wherein the orientation layer is a layer that has been subjected to a rubbing treatment.

9. The optical film according to claim 1 or 2, further comprising another liquid crystal layer different from the liquid crystal layer on the side of the adhesion layer opposite to the alignment layer side.

10. The optical film according to claim 1 or 2, wherein the optical film has a λ / 4 function.

11. The optical film according to claim 9, wherein the liquid crystal layer is a negative A plate, and the other liquid crystal layer includes a twisted liquid crystal layer and a C plate.

12. A polarizing plate comprising the optical film according to claim 1 or 2 and a polarizer.

13. A display device comprising the polarizing plate described in claim 12.

Images