Film, polarizing plate, and image display device

Abstract

The present invention provides a film that is applied to an image display element to obtain an image display device and is less susceptible to in-plane color unevenness when the image display device is viewed from an oblique direction during black display, a polarizing plate, and an image display device. A film according to the present invention comprises a retardation layer, a gradation layer, and an isotropic layer in this order. The retardation layer and the gradation layer are disposed adjacent to each other. The gradation layer and the isotropic layer are disposed adjacent to each other. All of the retardation layer, the gradation layer, and the isotropic layer contain a liquid crystal compound. The gradation layer is a layer having optical anisotropy that decreases from the retardation layer side toward the isotropic layer side. The retardation layer is an A plate, a C plate or a liquid crystal layer in which the liquid crystal compound is twisted and aligned at a twist angle of 180° or less.

Description

Films, polarizing plates, image display devices

[0001] The present invention relates to a film, a polarizing plate, and an image display device.

[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 optically anisotropic layer formed using a liquid crystal compound. Patent Document 1 discloses an embodiment in which the optically anisotropic layer includes a layer in which the orientation state of the liquid crystal compound is fixed and a layer in which the state of the liquid crystal compound exhibiting an isotropic phase is fixed.

[0004] International Publication No. 2022 / 030308

[0005] Recently, there has been a growing demand for further reduction of in-plane color unevenness in image display devices when viewing a black image from an oblique angle. The present inventors investigated an image display device using the optical anisotropy layer described in Patent Document 1 and found that it may not meet the standards currently required. In-plane color unevenness refers to the existence of areas with different colors within the surface.

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

[0007] As a result of diligent research to solve the above problems, the inventors have found that the problems can be solved by the following configuration.

[0008] (1) A film having a phase difference layer, a gradation layer, and an isotropic layer in this order, wherein the phase difference layer and the gradation layer are arranged adjacent to each other, the gradation layer and the isotropic layer are arranged adjacent to each other, the phase difference layer, the gradation layer, and the isotropic layer all contain a liquid crystal compound, the gradation layer is a layer in which optical anisotropy decreases from the phase difference layer side toward the isotropic layer side, and the phase difference layer is an A plate, a C plate, or a liquid crystal layer in which the liquid crystal compound is twisted and oriented at a twist angle of 180° or less. (2) The film according to (1), wherein the thickness of the gradation layer is 0.1 μm or more. (3) The film according to (1) or (2), wherein the phase difference layer is an A plate, or a liquid crystal layer in which the liquid crystal compound is twisted and oriented at a twist angle of 180° or less, and the gradation layer is a layer in which the birefringence Δn decreases from the phase difference layer side toward the isotropic layer side. (4) The film according to (1) or (2), wherein the phase difference layer is a C plate, and the gradation layer is a layer in which the absolute value of the retardation in the thickness direction decreases from the phase difference layer side toward the isotropic layer side. (5) The film according to any one of (1) to (4), further comprising an adjacent layer disposed adjacent to the isotropic layer on the opposite side from the gradation layer side, wherein the difference between the refractive index at the adjacent layer side surface of the isotropic layer and the refractive index at the isotropic layer side surface of the adjacent layer is 0.11 or less. (6) A polarizer comprising the film according to any one of (1) to (4) and a polarizer. (7) A polarizer comprising the film according to (5) and a polarizer, wherein the difference between the refractive index at the adjacent layer side surface of the isotropic layer and the refractive index at the isotropic layer side surface of the adjacent layer in the transmission axis direction of the polarizer is 0.11 or less. (8) An image display device comprising an image display element and the polarizer according to (6).

[0009] According to the present invention, when applied to an image display element to obtain an image display device, a film can be provided that, when displayed in black and viewed from an oblique direction, is less prone to in-plane color unevenness. Furthermore, according to the present invention, a polarizing plate and an image display device can be provided.

[0010] This is a diagram conceptually illustrating an example of the film of the present invention. This is a cross-sectional view of a composition layer illustrating an example of step 2 in the method for manufacturing the film of the present invention. This is a cross-sectional view of a composition layer illustrating an example of step 3 in the method for manufacturing the film of the present invention. This is a cross-sectional view of a composition layer illustrating an example of step 3 in the method for manufacturing the film of the present invention. This is a diagram illustrating the change in the birefringence Δn of an example of the film 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] Furthermore, 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 invention, Re(λ) and Rth(λ) are values ​​measured at wavelength λ using AxoScan (manufactured by Axometrics). By inputting the average refractive index ((nx + ny + nz) / 3) and film thickness (d) into 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 numerical value calculated by AxoScan, but it means Re(λ).

[0014] Furthermore, in this specification, the refractive indices nx, ny, and nz are measured using an Abbe refractometer (NAR-4T, manufactured by Atago Corporation) with a sodium lamp (λ = 589 nm) as the light source. Wavelength dependence can be measured using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Corporation) in combination with an interference filter. Values ​​from the Polymer Handbook (JOHN WILEY & SONS, INC.) and catalogs of various optical films can also be used. Examples of average refractive index values ​​for major optical films are given below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).

[0015] 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 given by equation (A1), and a negative A plate satisfies the relationship given by 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".

[0016] 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.

[0017] 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.

[0018] A key feature of the film of the present invention is the presence of a gradient layer between the phase difference layer and the isotropic layer. The gradient layer is a layer in which the optical anisotropy changes in the thickness direction, as will be described later. More specifically, the optical anisotropy decreases from the phase difference layer side toward the isotropic layer side. As a result, abrupt changes in optical anisotropy within the film are suppressed, and the occurrence of reflection is inhibited. It is presumed that by reducing the amount of reflected light in this way, in-plane color unevenness can be suppressed.

[0019] Figure 1 shows an example of the film of the present invention. As shown in Figure 1, the film 10 has a phase difference layer 12, a gradation layer 14, and an isotropic layer 16 in this order. The phase difference layer 12 and the gradation layer 14 are arranged adjacent to each other, and the gradation layer 14 and the isotropic layer 16 are arranged adjacent to each other. The phase difference layer 12, the gradation layer 14, and the isotropic layer 16 are all layers containing liquid crystal compounds, as will be described later. In other words, the phase difference layer 12, the gradation layer 14, and the isotropic layer 16 are all layers formed using liquid crystal compounds, as will be described later. The individual components included in the film 10 will be described in detail below.

[0020] <Phase Difference Layer> As described above, the phase difference layer is a layer containing a liquid crystal compound. Either a polymer liquid crystal compound or a low-molecular-weight liquid crystal compound can be used as the liquid crystal compound. Here, "polymer liquid crystal compound" refers to a liquid crystal compound that has repeating units in its chemical structure. "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, but a rod-shaped liquid crystal compound is preferred. Known compounds can be used as rod-shaped liquid crystal compounds, 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. Known compounds can be used as disc-shaped liquid crystal compounds, 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.

[0021] When the film of the present invention is applied to an image display element to obtain an image display device, and the image display device is viewed from an oblique direction in black display mode, it is preferable that the liquid crystal compound is an inverse wavelength dispersive liquid crystal compound in that it is less likely to cause in-plane color unevenness (hereinafter also simply referred to as "a point where the effect of the present invention is superior"). An inverse wavelength dispersive liquid crystal compound is one in which, when the in-plane retardation (Re) value of a phase difference film made by aligning (horizontally oriented) this liquid crystal compound is measured at a specific wavelength (visible light range), the Re value increases as the measured wavelength increases.

[0022] The liquid crystal compound in the phase difference 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 phase difference layer does not need to exhibit liquid crystalline properties anymore. For example, when a phase difference layer is formed using a polymerizable liquid crystal compound, the liquid crystal compound may lose its liquid crystalline properties due to the curing reaction, resulting in increased molecular weight.

[0023] The phase difference 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 aziridinyl groups, with unsaturated polymerizable groups being preferred and ethylenically unsaturated polymerizable groups being more preferred.

[0024] The phase difference layer is an A plate, a C plate, or a liquid crystal layer in which a liquid crystal compound is twisted and aligned at a twist angle of 180° or less. 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 λ / 2 plate. Note that the λ / 4 plate is a plate having a function of converting linearly polarized light of a specific wavelength into circularly polarized light (or converting circularly polarized light into linearly polarized light). More specifically, it is a plate in which the in-plane retardation Re at a predetermined wavelength λ nm indicates λ / 4 (or an odd multiple thereof). When the A plate is used as a λ / 4 plate, the in-plane retardation (Re(550)) of the A plate at a wavelength of 550 nm may have an error of about 25 nm around the ideal value (137.5 nm). For example, 110 to 160 nm is preferable, and 120 to 150 nm is more preferable. The λ / 2 plate refers to an optically anisotropic film in which the in-plane retardation Re(λ) at a specific wavelength λ nm satisfies Re(λ)≒λ / 2. This equation only needs to be achieved at any wavelength in the visible light region (for example, 550 nm). Among them, when the A plate is used as a λ / 2 plate, the in-plane retardation Re(550) of the A plate at a wavelength of 550 nm is preferably 210 to 300 nm.

[0025] The definition of the C plate is as described above. The retardation in the thickness direction of the C plate at a wavelength of 550 nm is not particularly limited, but in terms of more excellent effects of the present invention, -120 to -20 nm is preferable, and -100 to -30 nm is more preferable. Or, the retardation in the thickness direction of the C plate at a wavelength of 550 nm is not particularly limited, but in terms of more excellent effects of the present invention, 10 to 80 nm is preferable, and 20 to 60 nm is more preferable.

[0026] In a liquid crystal layer (hereinafter also referred to as "twisted liquid crystal layer") in which a 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, but 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 measuring method of the above twist angle and Δnd is measured using the AxoScan (polarimeter) device of Axometrics and the device analysis software of the same company.

[0027] Note that when a 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. Along with this, 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 the range of 0 to 20°, and more preferably within the range of 0 to 10°.

[0028] The thickness of the retardation layer is not particularly limited, preferably 10 μm or less, more preferably 0.1 to 5.0 μm, and even more preferably 0.5 to 3.0 μm.

[0029] <Gradient layer> As described above, the gradient layer is a layer containing a liquid crystal compound. The preferred embodiment of the liquid crystal compound is as described in the retardation layer.

[0030] The liquid crystal compound in the gradient layer may be fixed. Furthermore, the liquid crystal compound in the gradient layer may no longer exhibit liquid crystalline properties. For example, when a gradient layer is formed using a polymerizable liquid crystal compound, the liquid crystal compound may lose its liquid crystalline properties due to the curing reaction, resulting in increased molecular weight. The gradient layer is preferably formed using a composition containing a polymerizable liquid crystal compound.

[0031] The optical anisotropy of a gradient layer decreases from the phase difference layer side towards the isotropic layer side. In other words, the optical anisotropy of a gradient layer decreases in the thickness direction. Optical anisotropy means that there is anisotropy in the refractive index in any two directions selected from the three directions: the thickness direction of the layer and two mutually orthogonal in-plane directions. Examples of layers having optical anisotropy include a layer having a birefringence Δn and a layer having retardation in the thickness direction. Therefore, one preferred embodiment of a gradient layer is a layer in which the birefringence Δn decreases from the phase difference layer side towards the isotropic layer side. Another preferred embodiment of a gradient layer is a layer in which the absolute value of retardation in the thickness direction (particularly retardation in the thickness direction at a wavelength of 550 nm) decreases from the phase difference layer side towards the isotropic layer side. In the present invention, birefringence Δn means birefringence Δn at a wavelength of 550 nm. Furthermore, the birefringence Δn refers to the difference between the refractive index in the direction where the refractive index is maximum within the plane and the refractive index in the direction perpendicular to the direction where the refractive index is maximum.

[0032] The method of reducing the optical anisotropy of the gradation layer is not particularly limited; it may be reduced continuously or in steps. In particular, in terms of achieving superior effects of the present invention, it is preferable that the refractive index anisotropy of the gradation layer is reduced continuously from the phase difference layer side to the isotropic layer side. For example, if the gradation layer is a layer in which the birefringence Δn decreases from the phase difference layer side to the isotropic layer side, the birefringence Δn may be reduced continuously or in steps, and it is preferable that it is reduced continuously in terms of achieving superior effects of the present invention. Also, if the gradation layer is a layer in which the absolute value of the retardation in the thickness direction (especially the retardation in the thickness direction at a wavelength of 550 nm) decreases from the phase difference layer side to the isotropic layer side, the absolute value of the retardation in the thickness direction may be reduced continuously or in steps, and it is preferable that it is reduced continuously in terms of achieving superior effects of the present invention.

[0033] The degree of reduction in the optical anisotropy of the gradient layer can be adjusted by the degree of orientation of the liquid crystal compound, as will be described later. For example, if the liquid crystal compound is oriented in the in-plane direction, a disturbance in the orientation of the liquid crystal compound will cause a decrease in the birefringence Δn in the region where the disturbance occurs. Therefore, if the degree of orientation of the liquid crystal compound in the in-plane direction is reduced along the thickness direction of the gradient layer, the birefringence Δn can be gradually reduced along the thickness direction of the gradient layer. Also, if the degree of orientation of the liquid crystal compound in the out-of-plane direction (direction perpendicular to the in-plane direction) is reduced along the thickness direction of the gradient layer, the retardation in the thickness direction can be gradually reduced along the thickness direction of the gradient layer.

[0034] The thickness of the gradient layer is not particularly limited, but from the viewpoint of achieving superior effects of the present invention, it is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.3 μm or more. There is no particular upper limit, but from the viewpoint of thinning, it is preferably 5.0 μm or less, more preferably 1.0 μm or less, and even more preferably 0.5 μm or less.

[0035] <Isotropic Layer> As described above, the isotropic layer is a layer containing a liquid crystal compound. The preferred embodiment of the liquid crystal compound is as explained in the section on the phase difference layer.

[0036] The liquid crystal compound in the isotropic layer may be fixed. Furthermore, the liquid crystal compound in the isotropic layer may no longer exhibit liquid crystalline properties. For example, when an isotropic layer is formed using a polymerizable liquid crystal compound, the liquid crystal compound may lose its liquid crystalline properties due to the curing reaction, resulting in increased molecular weight. The isotropic layer is preferably a layer formed using a composition containing a polymerizable liquid crystal compound.

[0037] An isotropic layer is a layer that exhibits optical isotropy. Specifically, the in-plane retardation Re1(550) of the isotropic layer at a wavelength of 550 nm, and the thickness-direction retardation Rth1(550) of the isotropic layer at a wavelength of 550 nm, satisfy the relationships given by equations (1A) and (1B). Equation (1A): 0 nm ≤ Re1(550) ≤ 10 nm Equation (1B): -5 nm ≤ Rth1(550) ≤ 5 nm

[0038] The thickness of the isotropic layer is not particularly limited, but is preferably 10 μm or less, more preferably 0.1 to 5.0 μm, and even more preferably 0.3 to 2.0 μm.

[0039] <Preferred Embodiments> One preferred embodiment of the above film is embodiment X, in which the phase difference layer is an A plate or a twisted liquid crystal layer, and the gradation layer is a layer in which the birefringence Δn decreases from the phase difference layer side toward the isotropic layer side. In embodiment X, a birefringence Δn originating from the A plate and the twisted liquid crystal layer is generated on the surface of the phase difference layer toward the gradation layer side. Because the gradation layer is a layer in which the birefringence Δn decreases from the phase difference layer side toward the isotropic layer side, it is possible to suppress abrupt changes in the birefringence Δn from the phase difference layer to the isotropic layer, and the effects of the present invention are further enhanced.

[0040] In the above embodiment X, the difference between the birefringence Δn on the surface of the gradation layer on the phase difference layer side and the birefringence Δn on the surface of the phase difference layer on the gradation layer side is preferably 0.08 or less, more preferably 0.03 or less, and even more preferably 0, in terms of achieving superior effects of the present invention. Furthermore, in the above embodiment X, the birefringence Δn on the surface of the gradation layer on the isotropic layer side is preferably 0.08 or less, more preferably 0.03 or less, and even more preferably 0, in terms of achieving superior effects of the present invention.

[0041] In the above embodiment X, it is preferable that the in-plane slow axis on the phase difference layer side surface of the gradation layer and the in-plane slow axis on the gradation layer side surface of the phase difference layer are parallel. The "parallelism" between the in-plane slow axis on the phase difference layer side surface of the gradation layer and the in-plane slow axis on the gradation layer side surface of the phase difference layer includes the 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.

[0042] Another preferred embodiment of the above film is embodiment Y, in which the phase difference layer is a C plate, and the gradation layer is a layer in which the absolute value of the thickness-direction retardation (particularly the thickness-direction retardation at a wavelength of 550 nm) decreases from the phase difference layer side toward the isotropic layer side. In embodiment Y, thickness-direction retardation originating from the C plate occurs on the surface of the phase difference layer toward the gradation layer side. Because the gradation layer is a layer in which the absolute value of the thickness-direction retardation decreases from the phase difference layer side toward the isotropic layer side, it is possible to suppress abrupt changes in thickness-direction retardation from the phase difference layer to the isotropic layer, and the effects of the present invention are further enhanced.

[0043] In the above embodiment Y, the difference between the retardation in the thickness direction at a wavelength of 550 nm on the surface of the phase difference layer on the phase difference layer side and the retardation in the thickness direction at a wavelength of 550 nm on the surface of the phase difference layer on the phase difference layer side is preferably 5 nm or less, more preferably 3 nm or less, and even more preferably 0 nm, in terms of achieving superior effects of the present invention. Furthermore, in the above embodiment Y, the absolute value of the retardation in the thickness direction at a wavelength of 550 nm on the surface of the isotropic layer side of the gradient layer is preferably 5 nm or less, more preferably 3 nm or less, and even more preferably 0 nm, in terms of achieving superior effects of the present invention.

[0044] As described above, the film of the present invention includes a phase difference layer, a gradation layer, and an isotropic layer, and the thickness and refractive index of each layer can be measured by known methods. An example of the measurement method is shown below. First, transmission and reflection ellipsometry are performed using an ellipsometer in the wavelength range of 500 to 1500 nm. As ellipsometers, for example, the RC-2 manufactured by Woolam and the SE-2000 manufactured by Semilab can be used. 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. A treatment to reduce the back surface reflection intensity is to sand the back surface.

[0045] Based on the results obtained from the above measurements, an optical model is constructed assuming the existence of a phase difference layer, a gradation layer, and an isotropic layer in the thickness direction. The refractive index and thickness of each layer are calculated by fitting the model using the least squares method. Fitting is also performed for optical models with only a phase difference layer and models with both a phase difference layer and an isotropic layer, and the model with the best fitting convergence is adopted.

[0046] Regarding the refractive index of each layer, we follow the Cauchy model and use n(λ) = An + Bn / λ ２ Let An and Bn be variables, λ be the wavelength, and n(λ) be the refractive index at wavelength λ. The refractive index in the in-plane slow axis direction is given by the Cauchy model ne(λ) = Ane + Bne / λ ２ The refractive index in the direction of the in-plane phase advance axis is calculated using the Cauchy model no(λ) = Ano + Bno / λ ２ The calculations are performed using the following method. From the obtained ne(λ) and no(λ), the average values ​​of the birefringence and in-plane refractive index can also be calculated. Note that the refractive index, birefringence, and in-plane refractive index in each direction for each layer and region are taken from the values ​​at a wavelength of 550 nm.

[0047] Furthermore, in the film of the present invention, it is preferable that no leveling agent is present at the interface between the phase difference layer and the gradation layer. Moreover, in the film of the present invention, it is preferable that no leveling agent is present at the interface between the gradation layer and the isotropic layer. In the film obtained by the film manufacturing method having steps 1 to 5 described later, the above leveling agent is not present at the interfaces between each layer.

[0048] <Other Components> The film of the present invention may have other components besides the components described above (phase difference layer, gradation layer, isotropic layer). The film of the present invention may further have an adjacent layer that is positioned adjacent to the isotropic layer on the opposite side from the gradation layer. The type of adjacent layer is not particularly limited, but examples include adhesive layers such as an adhesive layer and a tack layer.

[0049] The difference between the refractive index of the adjacent layer surface of the isotropic layer and the refractive index of the adjacent layer surface of the isotropic layer is not particularly limited, but in terms of superior effects of the present invention, it is preferably 0.11 or less, more preferably 0.04 or less, and even more preferably 0.02 or less. The lower limit is not particularly limited, but 0 is an example.

[0050] The film of the present invention may include a support for supporting a phase difference layer, a gradation layer, and an isotropic layer. 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.

[0051] 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.

[0052] The film of the present invention may have an alignment layer. In particular, it may further have an alignment layer on the side opposite to the gradient layer of the phase difference layer. Known alignment layers can be used as the alignment layer. Examples include a rubbing-treated alignment layer and a photo-alignment layer.

[0053] <Method for Manufacturing Film> The method for manufacturing the film of the present invention is not particularly limited, but one embodiment of the manufacturing method is a method comprising the following steps 1 to 5. Step 1: A step of forming a composition layer containing a liquid crystal compound having polymerizable groups. Step 2: A step of heating the composition layer to orient the liquid crystal compound in the composition layer. Step 3: After step 2, a step of irradiating the composition layer with light under conditions of an oxygen concentration of 1 volume% or more. Step 4: Within 15 seconds after the completion of step 3, a step of heating the composition layer. Step 5: After step 4, a step of curing the light-irradiated composition layer to fix the orientation state of the liquid crystal compound and form a film having a phase difference layer, a gradation layer, and an isotropic layer. Each step will be described in detail below.

[0054] (Step 1) Step 1 is a step of forming a composition layer containing a liquid crystal compound having polymerizable groups. The embodiment of the liquid crystal compound having polymerizable groups is as described above.

[0055] The composition layer may contain components other than the liquid crystal compound having polymerizable groups. Examples of other components include chiral agents, polymerization initiators, surfactants, and orientation control agents (e.g., vertical and horizontal orientation agents). When the composition layer contains a chiral agent, the twisted liquid crystal layer described above can be formed as a phase difference layer.

[0056] In step 1, a composition layer containing the above-mentioned components is formed, but the procedure is not particularly limited. For example, one method is to coat a support with the composition containing the above-mentioned polymerizable liquid crystal compound and, if necessary, to perform a drying treatment (hereinafter also simply referred to as the "coating method"), and another method is to form a separate composition layer and transfer it onto the support. Among these, the coating method is preferred from the viewpoint of productivity. The composition used in the coating method includes the above-mentioned polymerizable liquid crystal compound and other components used as necessary (e.g., chiral agents, polymerization initiators, surfactants, orientation control agents, and solvents).

[0057] The coating method is not particularly limited and examples include wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. If necessary, a drying process may be performed on the composition layer after coating.

[0058] (Step 2) Step 2 is a process of heat-treating the composition layer to orient the liquid crystal compound in the composition layer. By performing this step, the liquid crystal compound in the composition layer will be in a predetermined orientation state. The optimal conditions for the heat treatment are selected according to the liquid crystal compound used. In particular, the heating temperature is often 25 to 250°C, more often 40 to 150°C, and even more often 50 to 130°C. The heating time is often 0.1 to 60 minutes, more often 0.2 to 5 minutes.

[0059] (Step 3) Step 3 is a step in which the composition layer is irradiated with light under conditions of an oxygen concentration of 1 volume% or more, after Step 2. The mechanism of this step will be explained below with reference to the drawings. In the following explanation, an example of performing Step 3 on the composition layer 22 shown in Figure 2 will be described as a representative example.

[0060] As shown in Figure 2, in step 2 described above, light irradiation is performed from the direction opposite to the composition layer 22 side of the support 20 (the direction of the white arrow in Figure 2) under conditions of an oxygen concentration of 1 volume% or more. In Figure 2, light irradiation is performed from the support 20 side, but it may also be performed from the composition layer 22 side. In this case, comparing the lower region 22A on the support 20 side of the composition layer 22 with the upper region 22B on the opposite side of the support 20, the surface of the upper region 22B is on the air side, so the oxygen concentration in the upper region 22B is high and the oxygen concentration in the lower region 22A is low. Therefore, when light irradiation is performed on the composition layer 22, polymerization of the liquid crystal compound proceeds easily in the lower region 22A, and the orientation state of the liquid crystal compound is fixed. Also, in the upper region 22B, because the oxygen concentration is high, even if light irradiation is performed, polymerization of the liquid crystal compound is inhibited by oxygen, and polymerization does not proceed easily. Therefore, when step 4 (heat treatment) described later is performed, the orientation state of the liquid crystal compound changes. In other words, by performing step 3, the orientation state of the liquid crystal compound is more easily fixed in the support-side region (lower region) of the composition layer. Conversely, in the region of the composition layer opposite the support-side (upper region), the orientation state of the liquid crystal compound is less easily fixed, and the orientation state of the liquid crystal compound is more prone to change.

[0061] Step 3 is carried out under conditions of an oxygen concentration of 1 volume percent or higher. In particular, an oxygen concentration of 2 volume percent or higher is preferred, and 5 volume percent or higher is more preferred, as it facilitates the formation of a thick gradient layer. There is no particular upper limit, but 100 volume percent is an example.

[0062] The light used for irradiation can be any light that causes polymerization of the liquid crystal compound having polymerizable groups. Examples of light used for irradiation include the emission line spectrum of a mercury lamp, far ultraviolet light represented by an excimer laser, extreme ultraviolet light, X-rays, ultraviolet light, and electron beams. Of these, ultraviolet light is preferred.

[0063] The amount of light irradiation in step 3 is not particularly limited, but 300 mJ / cm is recommended as it facilitates the formation of a thick gradient layer. ２ The following is preferable: 200 mJ / cm ２ The following is more preferable. As a lower limit, 10 mJ / cm is preferable in terms of the ease with which a predetermined optical anisotropy layer is formed. ２ The above is preferable, and 30 mJ / cm ２ The above is more preferable. The temperature of the light irradiation in step 3 is appropriately selected depending on the type of liquid crystal compound having polymerizable groups. For example, it is preferable to carry it out at 15 to 90°C (preferably 30 to 80°C). The above temperature is preferably below the temperature at which the liquid crystal compound becomes an isotropic phase.

[0064] <Step 4> Step 4 is a step in which the composition layer is subjected to heat treatment within 15 seconds after the completion of Step 3. By performing this step, the orientation state of the liquid crystal compound in the region of the composition layer opposite to the support side (upper region) changes. More specifically, this step is a step in which the composition layer after Step 3 is subjected to heat treatment to change the orientation state of the liquid crystal compound in the composition layer that was not fixed in Step 3.

[0065] The mechanism of this process will be explained below using the drawings. As described above, when step 3 is performed on the composition layer 22 shown in Figure 2, the orientation state of the liquid crystal compound is fixed in the lower region 22A, whereas polymerization of the liquid crystal compound does not proceed easily in the upper region 22B, and the orientation state of the liquid crystal compound is not fixed. Therefore, when step 4 is performed, the orientation state of the liquid crystal compound collapses in the upper region 22B because polymerization of the liquid crystal compound has not progressed. At that time, if a predetermined heat treatment is performed on the composition layer within 15 seconds after the completion of step 3, the orientation state of the liquid crystal compound located in the region adjacent to the lower region 22A among the liquid crystal compounds contained in the upper region 22B will gradually collapse along the thickness direction. In other words, in the region of the upper region 22B adjacent to the lower region 22A, the optical anisotropy decreases from the lower region 22A toward the upper region 22B.

[0066] As an example, Figures 3 and 4 show an embodiment in which the liquid crystal compound is a rod-shaped liquid crystal compound. Figure 3 shows the orientation state of the rod-shaped liquid crystal compound LC before carrying out step 4, and in both the lower region 22A and the upper region 22B, the rod-shaped liquid crystal compound LC is homogeneously oriented in a predetermined direction. Subsequently, when a predetermined heat treatment (preferably a heat treatment at a temperature above which the liquid crystal compound becomes an isotropic phase) is carried out in step 4, as shown in Figure 4, the rod-shaped liquid crystal compound LC contained in the region 22B1 adjacent to the lower region 22A of the upper region 22B tends to maintain its orientation relatively easily, and the rod-shaped liquid crystal compound LC tends to show an isotropic layer in the remaining region 22B2 of the upper region 22B. As a result, by carrying out step 5 described later, a gradient layer and an isotropic layer are formed. As an example of an embodiment including a phase difference layer, a gradient layer and an isotropic layer obtained by the configuration shown in Figures 3 and 4, as shown in Figure 5, the region of the phase difference layer shows a predetermined birefringence Δn, the region of the gradient layer shows a continuous decrease in birefringence Δn, and the region of the isotropic layer shows a birefringence Δn of 0. The reason why the rod-shaped liquid crystal compound LC contained in region 22B1 adjacent to the lower region 22A of the upper region 22B is relatively easy to maintain its orientation is presumed to be because the rod-shaped liquid crystal compound LC contained in the region adjacent to the lower region 22A of the upper region 22B is easily affected by the orientation-restricting force of the rod-shaped liquid crystal compound LC whose orientation state is fixed in the lower region 22A. In particular, by performing step 4 within a predetermined time from step 3, it is possible to maintain the state of step 3 as much as possible, and as a result, it is thought that the gradation layer is more easily formed.

[0067] Step 4 is performed within 15 seconds after the completion of Step 3, and is preferably performed within 10 seconds, more preferably within 5 seconds, and even more preferably within 1 second, in terms of achieving superior effects of the present invention.

[0068] The heat treatment is preferably carried out at a temperature above which the liquid crystal compound becomes isotropic. The heat treatment temperature is preferably higher than the temperature at which step 3 is performed. The optimal heat treatment temperature is selected as appropriate depending on the type of liquid crystal compound. Specifically, it is often 40 to 250°C, and more often 100 to 150°C. The heating time is often 0.01 to 60 minutes, and more often 0.03 to 5 minutes.

[0069] <Step 5> Step 5 is a process in which, after step 4D, the composition layer is subjected to a curing treatment to form a film having a phase difference layer, a gradation layer, and an isotropic layer. By performing this step, the orientation state of the liquid crystal compound in the composition layer is fixed, and as a result, a film with a predetermined structure is formed.

[0070] The curing method is not particularly limited and includes photocuring and thermocuring. Among these, photocuring is preferred, and ultraviolet irradiation is more preferred. For ultraviolet irradiation, a light source such as an ultraviolet lamp is used. The amount of light (e.g., ultraviolet) irradiated is not particularly limited, but is generally 100 to 800 mJ / cm². ２ A certain degree is preferable. The atmosphere during light irradiation is not particularly limited; light irradiation may be carried out in air or in an inert atmosphere. In particular, it is preferable that light irradiation be carried out at an oxygen concentration of less than 1 volume percent.

[0071] When photocuring is performed as a curing treatment, the temperature conditions during photocuring are not particularly limited, and any temperature that maintains the orientation of the liquid crystal compound in step 4 is acceptable. The difference between the temperature of the heat treatment in step 4 and the temperature during the photocuring treatment is preferably 30°C or less, and more preferably 15°C or less. The temperature of the heat treatment is preferably above the temperature at which the liquid crystal compound becomes an isotropic phase.

[0072] <Polarizing Plate> The polarizing plate of the present invention includes the above-mentioned film. More specifically, the polarizing plate of the present invention includes the above-mentioned film and a polarizer. The polarizing plate may contain multiple films of the present invention. The composition of the film is as described above.

[0073] A polarizer can be any component 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 then stretching it. A protective film may be placed on one or both sides of the polarizer.

[0074] 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 includes visible light absorbing substances (dichroic dyes), luminescent substances (fluorescent substances, phosphorescent substances), ultraviolet absorbing substances, infrared absorbing substances, nonlinear optical substances, carbon nanotubes, and inorganic substances (e.g., quantum rods). 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.

[0075] The luminous efficiency-corrected single transmittance of the polarizer is not particularly limited, but is preferably 42% or higher, and more preferably 43% or higher, in terms of superior effects of the present invention. There is no particular upper limit, but is preferably 48% or lower. The luminous efficiency-corrected single transmittance is calculated by the following method. For the polarizer, the transmittance in the direction of the absorption axis (T1) and the transmittance in the direction perpendicular to the absorption axis (T2) in the wavelength range of 380 to 780 nm are measured using a spectrophotometer with an integrating sphere [JASCO Corporation's "V7100"], and the single transmittance at each wavelength is calculated based on the following formula: Single transmittance (%) = (T1 + T2) / 2 The obtained single transmittance is corrected for luminous efficiency using the 2-degree field of view (C light source) of JIS Z 8701:1999 "Method of representing colors - XYZ color system and X10Y10Z10 color system" to determine the luminous efficiency-corrected single transmittance.

[0076] The arrangement relationship between the film and the polarizer of the present invention is not particularly limited, and the optimal arrangement can be selected as appropriate depending on the application. For example, when the phase difference layer in the film of the present invention is a λ / 4 plate, the angle between the in-plane slow axis of the phase difference layer of the film of the present invention and the absorption axis of the polarizer is preferably in the range of 45°±20°, and preferably in the range of 45°±10°, in terms of having excellent circular polarization characteristics of the polarizer.

[0077] The difference between the refractive index at the adjacent layer surface of the isotropic layer and the refractive index at the adjacent layer surface of the isotropic layer in the transmission axis direction of the polarizer is not particularly limited, but is preferably 0.11 or less, more preferably 0.04 or less, and even more preferably 0.02 or less, in terms of superior effects of the present invention. The lower limit is not particularly limited, but is 0.

[0078] <Applications> The film and polarizing plate of the present invention can be applied to various applications, for example, to image display devices. Examples of image display devices include liquid crystal displays, organic electroluminescent (EL) displays, micro-LED displays, head-up displays, and head-mounted displays. The image display device of the present invention preferably includes an image display element and the film or polarizing plate of the present invention. Liquid crystal display elements and organic EL display elements are preferred as image display elements.

[0079] The features of the present invention will be described in more detail below with reference to examples and comparative 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 specific examples shown below.

[0080] <Example 1> (Preparation of Cellulose Acylate Film (Support)) The following composition (cellulose acylate dope) was placed in a mixing tank, stirred, and then heated at 90°C for 10 minutes. The resulting composition was then filtered through filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm to prepare the dope. The solid content concentration of the dope was 23.5% by mass, and the solvent of the dope was methylene chloride / methanol / butanol = 81 / 18 / 1 (mass ratio).

[0081] ------------------------------------------------------------ Cellulose acylate dope ------------------------------------------------------------ Cellulose acylate (acetyl substitution degree 2.86, viscosity-average degree of polymerization 310) 100 parts by mass Compound 1 (shown in formula (S4) below) 8.0 parts by mass Compound 2 (shown in formula (S5) below) 2.0 parts by mass Compound 3 (shown in formula (S6) below) 0.2 parts by mass Compound 4 (shown in formula (S7) below) 0.02 parts by mass Silica particle dispersion (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 0.1 parts by mass Solvent (methylene chloride / methanol / butanol)

[0082]

[0083]

[0084]

[0085]

[0086] The dope prepared as described above was cast using a band deposition machine. The dope was cast from the die so that it was in contact with the metal support, and then the resulting web (film) was peeled off. The drum was made of stainless steel (SUS).

[0087] After the casting process, the obtained web (film) was peeled from the drum and dried for 20 minutes in a tenter device at 30-40°C during film transport, using clips to hold both ends of the web in place. Subsequently, the web was further dried by zone heating while being transported on a roll. The obtained web was knurled and then wound up. The resulting cellulose acylate film had a thickness of 40 μm, an in-plane retardation of 1 nm at a wavelength of 550 nm, and a thickness-direction retardation of 26 nm at a wavelength of 550 nm.

[0088] (Alkali saponification treatment) The obtained cellulose acetate film was passed through a dielectric heating roll at a temperature of 60°C. After raising the film surface temperature to 40°C, an alkali solution with the following composition was applied to the band surface of the film using a bar coater at an application rate of 14 ml / m ２ and then conveyed for 10 seconds under a steam type far-infrared heater manufactured by Noritake Company Limited heated to 110°C. Subsequently, pure water was applied at 3 ml / m ２ using the same bar coater. Next, after repeating the water washing by a fountain coater and water draining by an air knife three times, it was conveyed to a drying zone at 70°C for 10 seconds to be dried, and a cellulose acetate film subjected to alkali saponification treatment was produced.

[0089] ―――――――――――――――――――――――――――――――― Alkali solution ―――――――――――――――――――――――――――――――― Potassium hydroxide 4.7 parts by mass Water 15.8 parts by mass Isopropanol 63.7 parts by mass Surfactant: C 14 H 29 O(CH2CH2O) 20 H 1.0 part by mass Propylene glycol 14.8 parts by mass ――――――――――――――――――――――――――――――――

[0090] (Formation of alignment film) An alignment film coating solution with the following composition was continuously applied to the surface of the cellulose acetate film subjected to alkali saponification treatment using a #14 wire bar. It was dried with warm air at 60°C for 60 seconds and further with warm air at 100°C for 120 seconds.

[0091] -------------------------------------------------- Orientation film coating solution -------------------------------------------------- 10 parts by mass of the following polyvinyl alcohol 371 parts by mass of water 119 parts by mass of methanol 0.5 parts by mass of glutaraldehyde (crosslinking agent) 0.175 parts by mass of citrate ester (manufactured by Sankyo Chemical Co., Ltd.) --------------------------------------------------

[0092] Polyvinyl alcohol: Degree of polymerization 300 (The numerical value within each repeating unit represents the content (mass %) relative to the total number of repeating units.)

[0093]

[0094] (Formation of optically anisotropic layer) The orientation film prepared above was continuously rubbed. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle between the longitudinal direction of the film (transport direction) and the rotation axis of the rubbing roller was set to 76°. If the longitudinal direction of the film (transport direction) is set to 90°, and when observed from the film side, with the film width direction as the reference (0°) and clockwise direction represented as a positive value, the rotation axis of the rubbing roller is at -14°.

[0095] On the rubbing-treated alignment film described above, an optically anisotropic layer-forming composition (A) containing a disc-shaped liquid crystal compound of the following composition was applied using a Gieser coating machine to form a composition layer. Subsequently, the obtained composition layer was heated with 80°C hot air for 1 minute to dry the solvent and allow the disc-shaped liquid crystal compound to undergo orientation maturation, resulting in uniform orientation. Next, the obtained composition layer was irradiated with 320 nm LED-UV light from the air interface side at 40°C under air conditions (oxygen concentration approximately 21 vol%) (90 mJ / cm²). ２ The lower layer was cured. Ten seconds after the lower layer cured, it was heated at 100°C for 1 minute. Then, UV irradiation (100 mJ / cm²) was performed at 100°C while purging with nitrogen to maintain an atmosphere with an oxygen concentration of 100 ppm by volume or less. ２The orientation of the liquid crystal compound was fixed by the following procedure to form an optically anisotropic layer (1a) and obtain an optical film. The thickness of the optically anisotropic layer (1a) was 2.7 μm, and the retardation at 550 nm was 168 nm. Furthermore, the angle of the in-plane slow axis of the optically anisotropic layer (1a) was parallel to the rotation axis of the rubbing roller, and when the width direction of the film was set to 0° (the longitudinal direction was 90° counterclockwise and -90° clockwise), the in-plane slow axis was -14° when viewed from the optically anisotropic layer (1a) side. The layer structure of the optically anisotropic layer (1a) prepared above was confirmed by measuring the refractive index using the method described later. The optically anisotropic layer (1a) was confirmed to be composed of three layers exhibiting different optical anisotropies: a phase difference layer (negative A plate) in which a vertically oriented liquid crystal compound with a thickness of 1.8 μm is fixed on the cellulose acylate film side; an isotropic layer with a thickness of 0.8 μm that does not exhibit anisotropy on the air interface side; and a gradation layer with a thickness of 0.1 μm between the phase difference layer and the isotropic layer that exhibits a different orientation from the above two layers. The gradation layer was a layer in which the birefringence Δn continuously decreased from the phase difference layer side toward the isotropic layer side. Furthermore, the birefringence Δn on the surface of the phase difference layer toward the gradation layer was the same as the birefringence Δn on the surface of the gradation layer toward the phase difference layer. Also, the birefringence Δn on the surface of the gradation layer toward the isotropic layer was 0. The in-plane slow axis on the surface of the phase difference layer toward the gradation layer was parallel to the in-plane slow axis on the surface of the gradation layer toward the phase difference layer.

[0096] -------------------------------------------------- Composition for forming an optically anisotropic layer (A) -------------------------------------------------- 80 parts by mass of the following disc-shaped liquid crystal compound 1 20 parts by mass of the following disc-shaped liquid crystal compound 2 1.0 part by mass of the following alignment film interface alignment agent 1 0.18 parts by mass of the following siloxane compound A 17.0 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 6.0 parts by mass of photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan Co., Ltd.) 200 parts by mass of methyl ethyl ketone --------------------------------------------------

[0097] Disc-shaped liquid crystal compound 1

[0098]

[0099] Disc-shaped liquid crystal compound 2

[0100]

[0101] Orientation film interface orientation agent 1

[0102]

[0103] Siloxane-containing compound A (In the formula below, 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.)

[0104]

[0105] <Example 2> An optically anisotropic layer (2a) was formed in the same manner as in Example 1, except that the step of heating at 100°C for 1 minute 10 seconds after the curing of the lower layer was changed to heating at 100°C for 1 minute 5 seconds after curing. It was confirmed that the optically anisotropic layer (2a) was composed of three layers, a phase difference layer, a gradation layer, and an isotropic layer, similar to the optically anisotropic layer (1a) of Example 1.

[0106] <Example 3> An optically anisotropic layer (3a) was formed in the same manner as in Example 1, except that the step of heating at 100°C for 1 minute 10 seconds after the curing of the lower layer was changed to a step of heating at 100°C for 1 minute immediately after the curing of the lower layer (within 1 second after the curing of the lower layer). It was confirmed that the optically anisotropic layer (3a) was composed of three layers, a phase difference layer, a gradation layer, and an isotropic layer, similar to the optically anisotropic layer (1a) of Example 1.

[0107] <Example 4> An optical anisotropic layer-forming composition (B) containing a disc-shaped liquid crystal compound with the following composition was applied to the cellulose acylate film using a Gieser coating machine to form a composition layer. The film with the composition layer formed was heated with hot air at 116°C for 1 minute, and then irradiated with a 365 nm UV-LED at a dose of 150 mJ / cm² under air (oxygen concentration approximately 21 vol%) at a temperature of 78°C. ２ The lower layer was cured by irradiating it with ultraviolet light. Immediately after the lower layer cured (within 1 second of the lower layer curing), it was heated at 130°C for 1 minute. Then, UV irradiation (100 mJ / cm²) was performed at 120°C while purging with nitrogen to maintain an atmosphere with an oxygen concentration of 100 ppm by volume or less. ２The orientation of the liquid crystal compound was fixed by the following procedure, and an optically anisotropic layer (4a) was formed to obtain an optical film. The layer structure of the optically anisotropic layer (4a) was confirmed in the same manner as in Example 1. It was confirmed that the optically anisotropic layer (4a) is composed of three layers exhibiting different optical anisotropy: a phase difference layer (negative C plate) in which a horizontally oriented liquid crystal compound with a thickness of 0.5 μm is fixed on the cellulose acylate film side, an isotropic layer with a thickness of 0.8 μm that does not exhibit anisotropy on the air interface side, and a gradation layer with a thickness of 0.3 μm that exhibits an orientation different from the above two layers between the phase difference layer and the isotropic layer. The gradation layer was a layer in which the retardation in the thickness direction at a wavelength of 550 nm continuously decreases from the phase difference layer side toward the isotropic layer side. Furthermore, the retardation in the thickness direction at a wavelength of 550 nm on the surface of the phase difference layer on the gradation layer side and the retardation in the thickness direction at a wavelength of 550 nm on the surface of the gradation layer on the phase difference layer side were the same value. Furthermore, the retardation in the thickness direction at a wavelength of 550 nm on the isotropic layer side surface of the gradient layer was 0.

[0108] -------------------------------------------------- Composition for forming an optically anisotropic layer (B) -------------------------------------------------- 4 parts by mass of the above disc-shaped liquid crystal compound 1 1 part by mass of the above disc-shaped liquid crystal compound 2 95.0 parts by mass of the following disc-shaped liquid crystal compound 3 Ethylene oxide modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 20.0 parts by mass Photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan Co., Ltd.) 3.0 parts by mass of the following fluorine-containing compound B 0.6 parts by mass Methyl isobutyl ketone 361 parts by mass Ethyl propionate 90 parts by mass Methyl ethyl ketone 24 parts by mass --------------------------------------------------

[0109] Disc-shaped liquid crystal compound 3

[0110]

[0111] Fluorine-containing compound B (The numerical value in each repeating unit represents the content (mass %) relative to the total repeating units. The weight-average molecular weight was 12,500.)

[0112]

[0113] <Example 5> The alignment film prepared in Example 1 was continuously rubbed. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle between the longitudinal direction (transport direction) of the film and the rotation axis of the rubbing roller was set to 45°. On this, an optical anisotropic layer-forming composition (C) containing a rod-shaped liquid crystal compound of the following composition was applied using a Gieser coating machine and heated with hot air at 70°C for 60 seconds. Subsequently, the obtained composition layer was irradiated with 320 nm LED-UV from the air interface side at 40°C under atmospheric conditions (oxygen concentration of approximately 21 vol%) (90 mJ / cm²). ２ The lower layer was cured. Immediately after the lower layer cured (within 1 second of the lower layer curing), it was heated at 120°C for 1 minute. Then, UV irradiation (100 mJ / cm²) was performed at 120°C while purging with nitrogen to reduce the oxygen concentration to 1% or less. ２The orientation of the liquid crystal compound was fixed by performing the following procedure to fabricate an optically anisotropic layer (5a) and obtain an optical film. The retardation of the optically anisotropic layer (5a) at 550 nm was 142 nm. When the width direction of the film is 0° (the longitudinal direction is 90°), the orientation axis angle of the liquid crystal compound, when viewed from the optically anisotropic layer (5a) side, was 45°. The layer structure of the optically anisotropic layer (5a) was confirmed in the same manner as in Example 1. It was confirmed that the optically anisotropic layer (5a) is composed of three layers exhibiting different optical anisotropies: a phase difference layer (positive A plate) on the cellulose acylate film side in which a horizontally oriented liquid crystal compound with a thickness of 1.5 μm is fixed; an isotropic layer with a thickness of 0.8 μm that does not show anisotropy on the air interface side; and a gradation layer with a thickness of 0.3 μm between the phase difference layer and the isotropic layer that shows a different orientation from the above two layers. Furthermore, the gradient layer was a layer in which the birefringence Δn continuously decreased from the phase difference layer side toward the isotropic layer side. Also, the birefringence Δn at the surface of the phase difference layer toward the gradient layer side was the same as the birefringence Δn at the surface of the gradient layer toward the phase difference layer side. In addition, the birefringence Δn at the surface of the gradient layer toward the isotropic layer side was 0.

[0114] -------------------------------------------------- Composition for forming an optically anisotropic layer (C) -------------------------------------------------- The following 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 (Irgacre 819, manufactured by BASF) 3 parts by mass The following siloxane-containing compound D 0.20 parts by mass Methyl isobutyl ketone 126 parts by mass Ethyl propionate 126 parts by mass --------------------------------------------------

[0115] Rod-shaped liquid crystal compound (A) (hereinafter referred to as a mixture of compounds)

[0116]

[0117] Rod-shaped liquid crystal compound (B)

[0118]

[0119] Siloxane-containing compound D (a, b, and c represent the content (mass%) of each repeating unit relative to the total repeating units, where a is 56% by mass, b is 36% by mass, and c is 8% by mass. The weight-average molecular weight was 17,000.)

[0120]

[0121] <Example 6> On the rubbing-treated alignment film described above, an optically anisotropic layer-forming composition (D) containing a disc-shaped liquid crystal compound of the following composition was applied using a Gieser coating machine to form a composition layer. Subsequently, the obtained composition layer was heated with 80°C hot air for 1 minute to dry the solvent and allow the disc-shaped liquid crystal compound to mature and become uniformly aligned. Then, the obtained composition layer was irradiated with 320 nm LED-UV from the air interface side at 40°C under air conditions (oxygen concentration approximately 21 vol%) (90 mJ / cm²). ２ The lower layer was cured. Immediately after the lower layer cured (within 1 second of the lower layer curing), it was heated at 130°C for 1 minute. Then, UV irradiation (100 mJ / cm²) was performed at 120°C while purging with nitrogen to maintain an atmosphere with an oxygen concentration of 100 ppm by volume or less. ２The orientation of the liquid crystal compound was fixed by the following procedure to form an optically anisotropic layer (6a). The layer structure of the optically anisotropic layer (6a) was confirmed in the same manner as in Example 1. The optically anisotropic layer (6a) was confirmed to consist of three layers exhibiting different optical anisotropies: a phase difference layer (twisted-oriented liquid crystal layer) on the cellulose acylate film side, in which a liquid crystal compound with a thickness of 1.5 μm, a twist angle of 81°, and a product Δnd of the birefringence and thickness at a wavelength of 550 nm of 165 nm was fixed; an isotropic layer with a thickness of 0.8 μm that does not exhibit anisotropy on the air interface side; and a gradation layer with a thickness of 0.3 μm between the phase difference layer and the isotropic layer that exhibits a different orientation from the above two layers. The gradation layer was a layer in which the birefringence Δn continuously decreased from the phase difference layer side toward the isotropic layer side. Furthermore, the birefringence Δn on the surface of the phase difference layer toward the gradation layer and the birefringence Δn on the surface of the gradation layer toward the phase difference layer were the same value. Furthermore, the birefringence Δn on the isotropic layer side of the gradient layer was 0.

[0122] -------------------------------------------------- Composition for forming an optically anisotropic layer (D) -------------------------------------------------- ・Disc-shaped liquid crystal compound 1 above 80 parts by mass ・Disc-shaped liquid crystal compound 2 above 20 parts by mass ・Orientation film interface orientation agent 1 above 1 part by mass ・Orientation film interface adhesion agent below 0.1 parts by mass ・Right-twist chiral agent below 0.27 parts by mass ・Leveling agent B-1 below 0.18 parts by mass ・Modified trimethylolpropane triacrylate below 5 parts by mass ・Photopolymerization initiator (Irgacre 819, manufactured by BASF) 4 parts by mass ・Defoaming agent below 2 parts by mass ・Methyl ethyl ketone 105 parts by mass --------------------------------------------------

[0123] Alignment film interface adhesive

[0124]

[0125] Right-handed chiral agent

[0126]

[0127] Leveling agent B-1 (weight-average molecular weight: 15000) (The wt% value indicated for each repeating unit represents the content (mass%) of each repeating unit relative to the total number of repeating units.)

[0128]

[0129] Modified trimethylolpropane triacrylate

[0130]

[0131] defoaming agent

[0132]

[0133] <Example 7> The alignment film prepared in Example 1 was continuously rubbed. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle between the longitudinal direction (transport direction) of the film and the rotation axis of the rubbing roller was set to 85°. The position of the rotation axis of the rubbing roller was rotated 85° clockwise with respect to the longitudinal direction of the film. On this, an optical anisotropic layer-forming composition (E) containing a rod-shaped liquid crystal compound of the following composition was applied using a Gieser coating machine and heated with hot air at 70°C for 60 seconds. Subsequently, the obtained composition layer was irradiated with 320 nm LED-UV from the air interface side at 40°C under atmospheric conditions (oxygen concentration of approximately 21 vol%) (90 mJ / cm²). ２ The lower layer was cured. Immediately after the lower layer cured (within 1 second of the lower layer curing), it was heated at 120°C for 1 minute. Then, UV irradiation (100 mJ / cm²) was performed at 120°C while purging with nitrogen to reduce the oxygen concentration to 1% or less. ２The orientation of the liquid crystal compound was fixed by performing the following procedure to form an optically anisotropic layer (7a) and obtain an optical film. The twist angle of the liquid crystal compound is expressed by observing the support from the surface side of the optically anisotropic layer (7a), 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 support side (back side) being negative and a counterclockwise (leftward) orientation being positive. The layer structure of the optically anisotropic layer (7a) was confirmed in the same manner as in Example 1. The optically anisotropic layer (7a) was confirmed to consist of three layers exhibiting different optical anisotropies: a phase difference layer (twisted liquid crystal layer) on the support side, which is made of a liquid crystal compound with a thickness of 1.5 μm, a twist angle of 81°, and a product Δnd of the birefringence and thickness at a wavelength of 550 nm of 165 nm; an isotropic layer with a thickness of 0.8 μm that does not exhibit optical anisotropy on the air interface side; and a gradation layer with a thickness of 0.3 μm between the phase difference layer and the isotropic layer that exhibits a different orientation from the above two layers. The gradation layer was a layer in which the birefringence Δn continuously decreased from the phase difference layer side toward the isotropic layer side. Furthermore, the birefringence Δn on the surface of the phase difference layer toward the gradation layer was the same as the birefringence Δn on the surface of the gradation layer toward the phase difference layer. Also, the birefringence Δn on the surface of the gradation layer toward the isotropic layer was 0. The in-plane slow axis on the surface of the phase difference layer toward the gradation layer was parallel to the in-plane slow axis on the surface of the gradation layer toward the phase difference layer.

[0134] -------------------------------------------------- Composition for forming an optically anisotropic layer (E) -------------------------------------------------- The above rod-shaped liquid crystal compound (A) 70 parts by mass The above 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-handed chiral agent (L1) 0.50 parts by mass The above siloxane-containing compound D 0.20 parts by mass Methyl isobutyl ketone 126 parts by mass Ethyl propionate 126 parts by mass --------------------------------------------------

[0135] Left-hand twist chiral agent (L1) (Bu represents a butyl group)

[0136]

[0137] <Example 8> A photo-alignment film-forming coating solution with the following composition was continuously applied to the cellulose acylate film described above using a wire bar. The cellulose acylate film with the coating was dried with 140°C hot air for 120 seconds, and then polarized ultraviolet light (10 mJ / cm²) was irradiated onto the coating. ２ By using an ultra-high pressure mercury lamp, a photo-alignment film with a thickness of 0.2 μm was formed, and a TAC film with a photo-alignment film was obtained. -------------------

[0138] Polymer PA-2 (weight-average molecular weight: 45,000) (In the formula below, the numerical values ​​listed for each repeating unit represent the content (mass %) of each repeating unit relative to the total number of repeating units.)

[0139]

[0140] Acid Generator CPI-110TF

[0141]

[0142] A composition (F) for forming an optically anisotropic layer was applied onto the photo-alignment film E1 using a bar coater. The coating formed on the photo-alignment film E1 was heated to 120°C with hot air, and then the resulting composition layer was irradiated with 320 nm LED-UV light from the air interface side at 40°C under atmospheric conditions (oxygen concentration approximately 21 vol%) (90 mJ / cm²). ２ The lower layer was cured. Immediately after the lower layer cured (within 1 second of the lower layer curing), it was heated at 120°C for 1 minute. Then, UV irradiation (100 mJ / cm²) was performed at 120°C while purging with nitrogen to reduce the oxygen concentration to 1% or less. ２The orientation of the liquid crystal compound was fixed by the following procedure to form an optically anisotropic layer (8a) and obtain an optical film. The layer structure of the optically anisotropic layer (8a) was confirmed in the same manner as in Example 1. The optically anisotropic layer (8a) was confirmed to consist of three layers exhibiting different optical anisotropy: a phase difference layer (positive A plate) on the support side in which a liquid crystal compound with a thickness of 2.5 μm and an in-plane retardation of 144 nm at a wavelength of 550 nm is fixed; an isotropic layer with a thickness of 0.8 μm that does not exhibit optical anisotropy on the air interface side; and a gradation layer with a thickness of 0.3 μm between the phase difference layer and the isotropic layer that exhibits a different orientation from the above two layers. The gradation layer was a layer in which the birefringence Δn continuously decreased from the phase difference layer side toward the isotropic layer side. Furthermore, the birefringence Δn on the surface of the phase difference layer toward the gradation layer and the birefringence Δn on the surface of the gradation layer toward the phase difference layer were the same value. Furthermore, the birefringence Δn on the surface of the gradation layer toward the isotropic layer was 0. The in-plane slow axis on the surface of the phase difference layer facing the gradient layer was parallel to the in-plane slow axis on the surface of the gradient layer facing the phase difference layer.

[0143] --------------------------------------------------- Composition for forming an optically anisotropic layer (F) --------------------------------------------------- ・Polymerizable liquid crystal compound LA-1 below 30.00 parts by mass ・Polymerizable liquid crystal compound LA-2 below 30.00 parts by mass ・Polymerizable liquid crystal compound LA-3 below 27.00 parts by mass ・Polymerizable liquid crystal compound LA-4 below 8.00 parts by mass ・Polymerizable liquid crystal compound LA-5 below 5.00 parts by mass ・Photopolymerization initiator (Irgacre 819, manufactured by BASF) 3 parts by mass ・The above siloxane-containing compound D 0.06 parts by mass ・Cyclopentanone 235.00 parts by mass ---------------------------------------------------

[0144] Polymerizable liquid crystal compound LA-1 (tBu represents a tert-butyl group)

[0145]

[0146] Polymerizable liquid crystal compound LA-2

[0147]

[0148] Polymerizable liquid crystal compound LA-3

[0149]

[0150] Polymerizable liquid crystal compound LA-4

[0151]

[0152] Polymerizable liquid crystal compound LA-5 (Me represents a methyl group)

[0153]

[0154] <Comparative Example 1> Similar to Example 1, an optically anisotropic layer-forming composition (G) containing a disc-shaped liquid crystal compound of the following composition was applied to the rubbing-treated alignment film using a Gieser coating machine to form a composition layer. Subsequently, the obtained composition layer was heated with 75°C hot air for 2 minutes to dry the solvent and allow the disc-shaped liquid crystal compound to align and mature, resulting in uniform orientation. Subsequently, the obtained composition layer was subjected to UV irradiation (100 mJ / cm²) while purging with nitrogen at 77°C to maintain an atmosphere with an oxygen concentration of 100 ppm by volume or less. ２ The orientation of the liquid crystal compound was fixed by ) and an optically anisotropic layer (C1) was formed to obtain an optical film. The thickness of the optically anisotropic layer (C1) was 1.7 μm, and the in-plane retardation at 550 nm was 168 nm. The value obtained by dividing the in-plane retardation at a wavelength of 550 nm by the thickness of the optically anisotropic layer (C1) was 0.099. Furthermore, the angle of the in-plane slow axis of the optically anisotropic layer (C1) was parallel to the rotation axis of the rubbing roller, and when the width direction of the film was set to 0° (the longitudinal direction was 90° counterclockwise and -90° clockwise), the in-plane slow axis when viewed from the optically anisotropic layer (C1) side was -14°. When the layer structure of the optically anisotropic layer (C1) was confirmed in the same manner as in Example 1, it was found to consist only of a phase difference layer (A plate) in which vertically oriented liquid crystal compounds were fixed. In other words, the optically anisotropic layer (C1) did not contain a gradient layer.

[0155] -------------------------------------------------- Composition for forming an optically anisotropic layer (G) -------------------------------------------------- 80 parts by mass of the above disc-shaped liquid crystal compound 1 20 parts by mass of the above disc-shaped liquid crystal compound 2 0.15 parts by mass of the above alignment film interface alignment agent 1 0.18 parts by mass of the above siloxane-containing compound A 13.0 parts by mass of ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 6.0 parts by mass of photopolymerization initiator (APi-307, manufactured by Shenzhen UV ChemTech Ltd.) 200 parts by mass of methyl ethyl ketone --------------------------------------------------

[0156] <Comparative Example 2> An optically anisotropic layer (C2) was formed in the same manner as in Example 1, except that the step of heating at 100°C for 1 minute 10 seconds after the curing of the lower layer was changed to heating at 100°C for 1 minute 20 seconds after the curing of the lower layer. When the layer structure of the optically anisotropic layer (C2) was confirmed in the same manner as in Example 1, two layers were confirmed: a phase difference layer (A plate) with vertically oriented liquid crystal compounds fixed in place, and an isotropic layer. The optically anisotropic layer (C2) did not contain a gradient layer.

[0157] <Evaluation> (Refractive Index, Film Thickness) The thickness of each layer contained in the optical anisotropic layer of each example and comparative example, and the refractive index of the optical anisotropic layer were measured using the method described above. The results are shown in the table below. Note that the refractive index shown in the table is the value on the surface side (air interface side) of the optical anisotropic layer.

[0158] (In-plane color unevenness) [Glass with AR layer] An inorganic oxide layer (AR layer) was formed on glass that had undergone chemical strengthening treatment. Specifically, the AR layer was formed by sputtering under arbitrary deposition pressure conditions, with the layer structure being Nb from the glass side. ２ O ５ / SiO ２ / Nb ２ O ５ / SiO ２ The film was deposited so that the thickness of each layer was 15 nm, 25 nm, 105 nm, and 85 nm, respectively, to fabricate glass with an AR layer.

[0159] [Fabrication of Linear Polarizers] 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 of polyvinyl alcohol (PVA) film with a thickness of 60 μm was continuously stretched in the longitudinal direction in an iodine aqueous solution and dried to obtain a linear polarizer with a thickness of 13 μm. The luminous efficiency corrected single transmittance of the linear polarizer was 43%. At this time, the absorption axis direction and the longitudinal direction of the linear polarizer coincided. The linear polarizer protective film was bonded to one side of the above linear polarizer using the PVA adhesive described below.

[0160] -Preparation of PVA adhesive- A PVA adhesive was prepared by dissolving 100 parts by mass of a polyvinyl alcohol-based resin having acetoacetyl groups (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, degree of acetoacetylation: 5 mol%) and 20 parts by mass of 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.

[0161] Using the optical films of Examples 1 to 8 and Comparative Examples 1 to 2, samples were obtained by laminating a black acrylic plate (Acrylite L502 black, manufactured by Mitsubishi Chemical Corporation) / pressure-sensitive adhesive (refractive index 1.47) / optical film / adhesive (refractive index 1.51) / linear polarizer / polarizer protective film / adhesive / AR layered glass in that order. At that time, the optical film was positioned so that the isotropic layer side was on the AR layered glass side, and the angle between the in-plane slow phase axis of the phase difference layer and the transmission axis of the polarizer was 45°. The laminated body including the black acrylic plate obtained above 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 laminated body, 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), a sample was set via a diffuser plate at an azimuth angle where the long axis of the rod-shaped fluorescent lamp and the long direction of the polarizing plate were perpendicular, and the color within the plane was observed from an extreme angle of 30-40°. When setting the sample, the AR-coated glass was set so that it faced the fluorescent lamp. This allowed for evaluation of the color unevenness within the plane when viewed from an oblique direction. The evaluation criteria were as follows: A: Almost no color unevenness was visible within the plane. B: Only very slight color unevenness was visible within the plane. C: Slight color unevenness was visible within the plane, but there is no problem in use. D: Color unevenness was visible within the plane, but there is no problem in use. E: Strong color unevenness was visible within the plane, and there is a problem in use. F: Very strong color unevenness was visible within the plane, and there is a problem in use.

[0162] In Table 1, the "Liquid Crystal Type" column indicates the type of liquid crystal compound contained in the phase difference layer, gradient layer, and isotropic layer. "DLC" represents a disc-shaped liquid crystal compound, "CLC" represents a rod-shaped liquid crystal compound, and "Inverse Dispersion CLC" represents a rod-shaped liquid crystal compound exhibiting inverse wavelength dispersion. In Table 1, the "Liquid Crystal Layer Details" column indicates the composition of the resulting layers. "Negative A" represents a negative A plate, "Iso" represents an isotropic layer, "Gradient" represents a gradient layer, "Positive A" represents a positive A plate, and "Twisted" represents a twisted liquid crystal layer. For example, "Negative A / Gradient / Iso" in Example 1 indicates that the negative A plate, gradient layer, and isotropic layer are stacked in this order. In Table 1, the "Refractive Index" column indicates the refractive index of the isotropic layer.

[0163]

[0164] As shown in Table 1, it was confirmed that the desired effect could be obtained when the film of the present invention was used. From a comparison of Examples 1 to 3, it was confirmed that the effect was superior when the thickness of the gradient layer was 0.2 μm or more (preferably 0.3 μm or more). Furthermore, from a comparison of Example 5 with the other examples, it was confirmed that the effect was superior when the phase difference layer was a positive A plate. Furthermore, from a comparison of Example 8 with the other examples, it was confirmed that the effect was superior when an inverse wavelength dispersive liquid crystal compound was used.

[0165] <Example 9> (Formation of Positive C Plate Layer) On the cellulose acylate film prepared above, an optically anisotropic layer-forming composition (H) containing a rod-shaped liquid crystal compound of 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. ２The 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, an optically anisotropic layer (1c), which is a positive C plate layer with orientation control capabilities, was formed on the surface. The thickness of the formed positive C plate layer was 0.6 μm. The in-plane retardation at a wavelength of 550 nm was 0 nm, and the retardation in the thickness direction at a wavelength of 550 nm was -80 nm. The average 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.

[0166] -------------------------------------------------- Composition for forming an optically anisotropic layer (H) -------------------------------------------------- The above rod-shaped liquid crystal compound (A) 100 parts by mass Polymerizable monomer (A-400, manufactured by Shin Nakamura Chemical Industry Co., Ltd.) 4.0 parts by mass Polymerization initiator S-1 (oxime type) 5.0 parts by mass Photoacid generator D-1 3.0 parts by mass Polymer M-1 2.0 parts by mass Vertical alignment agent S01 2.0 parts by mass Photo-aligning polymer A-1 2.0 parts by mass Methyl ethyl ketone 42.3 parts by mass Methyl isobutyl ketone 627.5 parts by mass --------------------------------------------------

[0167] Polymerization initiator S-1

[0168]

[0169] Photoacid Generator D-1

[0170]

[0171] Polymer M-1 (The numerical value in each repeating unit represents the content (mass %) relative to the total number of repeating units. The weight-average molecular weight was 58,000.)

[0172]

[0173] Vertical alignment agent S01

[0174]

[0175] Photo-oriented polymer A-1 (in the formula below, a, b, and c represent the content (mass%) of each repeating unit relative to the total number of repeating units, where a is 34% by mass, b is 26% by mass, and c is 40% by mass. The weight-average molecular weight was 100,000). Me represents a methyl group.

[0176]

[0177] (Formation of the twisted layer) Next, an optical anisotropic layer-forming composition (I) containing a rod-shaped liquid crystal compound of the following composition was applied to the optical anisotropic layer (1c) prepared above using a Gieser coating machine, and heated with hot air at 60°C for 60 seconds. Subsequently, the resulting composition layer was irradiated with UV at 80°C (300 mJ / cm²). ２ The 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 1.5 μm, Δnd at a wavelength of 550 nm was 164 nm, and the twist angle of the liquid crystal compound was 81°. When the width direction of the film 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 support from the surface side of the optically anisotropic layer, with the width direction of the support being 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 support 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 support side (backward side) being considered negative, and a counterclockwise (leftward) orientation angle being considered positive.

[0178] -------------------------------------------------- Composition for forming an optically anisotropic layer (I) -------------------------------------------------- The above rod-shaped liquid crystal compound (A) 70 parts by mass The above 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) 0.50 parts by mass The following fluorine-containing compound E 0.20 parts by mass Methyl isobutyl ketone 126 parts by mass Ethyl propionate 126 parts by mass --------------------------------------------------

[0179] Left-hand twist chiral agent (L1)

[0180]

[0181] Fluorine-containing compound E (The content of the repeating units on the left was 76% by mass, the content of the repeating units on the right was 24% by mass, and the weight-average molecular weight was 27,500.)

[0182]

[0183] Following the procedure described above, an optically anisotropic layer (1b-1c) was fabricated by directly laminating an optically anisotropic layer (1c) and an optically anisotropic layer (1b) onto a long cellulose acylate film. Upon examination of the surface of the optically anisotropic layer (1c) in contact with the optically anisotropic layer (1b), the presence of a photo-oriented polymer was confirmed.

[0184] (Fabrication of optical film) Corona discharge treatment was performed on the surface side (isotropic layer side) of the optical anisotropic layer (1a) of the optical film of Example 1. The conditions for the corona discharge treatment were an output intensity of 2.5 kW, a line speed of 18 m / min, an electrode length of 1.4 m, and a gap distance of 2 mm. The UV-curable adhesive (2a) described below was coated onto the corona-treated surface to a film thickness of 1.5 μm. Corona discharge treatment was also performed on the surface side of the optical anisotropic layer (1b) of the optical anisotropic layer (1c-1b) formed on the long cellulose acylate film prepared above. The conditions for the corona discharge treatment were an output intensity of 5.0 kW, a line speed of 18 m / min, an electrode length of 1.4 m, and a gap distance of 2 mm. The adhesive (2a) described below was coated onto the corona-treated surface to a film thickness of 1.0 μm. An adhesive (2a) coated on an optically anisotropic layer (1a) and an adhesive (2a) coated on an optically anisotropic layer (1b) were bonded together, heated to 50°C using an IR heater, and UV light was irradiated from both sides of the bonded cellulose acylate film to cure the adhesive (2a), after which it was heat-dried at 70°C for 3 minutes. This yielded an optical film (1a-1b-1c) having a layer structure of optically anisotropic layer (1a) - adhesive layer (2a) - optically anisotropic layer (1b-1c). In the optical film (1a-1b-1c), the optically anisotropic layer (1b) was positioned on the adhesive layer (2a) side. The in-plane retardation of the optical film (1a-1b-1c) at a wavelength of 550 nm was 141 nm.

[0185] -------------------------------------------------- Adhesive (2a) -------------------------------------------------- Acryloylmorpholine (manufactured by Kojinsha) 40 parts by mass N-Hydroxyacrylamide (manufactured by Kojinsha) 40 parts by mass Tripropylene glycol diacrylate (Aronics M-220, manufactured by Toagosei Co., Ltd.) 20 parts by mass Photopolymerization initiator (KAYACURE DETX-S, manufactured by Nippon Kayaku Co., Ltd.) 1.5 parts by mass

[0186] (Fabrication of linear polarizers) Following the same procedure as described in <Evaluation> above (Fabrication of linear polarizers), linear polarizers with polarizer protective films attached were fabricated.

[0187] <Fabrication of Polarizing Plates> The cellulose acylate film was peeled from the optical film of Example 1 to expose the optical anisotropy layer, and the exposed surface was subjected to corona discharge treatment. The corona discharge treatment conditions were: output intensity 2.5 kW, line speed 18 m / min, electrode length 1.4 m, and gap distance 2 mm. The adhesive (2a) described above was coated onto the corona-treated surface to a film thickness of 1.5 μm. The opposite side of the polarizer protective film of the long linear polarizer fabricated above was bonded to the side of the optical film (1a-1b-1c) coated with adhesive (2a), and the adhesive (2a) was cured using the same method as described above to obtain a laminate of linear polarizer - optical anisotropy layer (1a) - adhesive layer (2a) - optical anisotropy layer (1b-1c). Next, the cellulose acylate film on the optically anisotropic layer (1b-1c) side was peeled off, exposing the surface of the optically anisotropic layer (1b-1c) that had been in contact with the cellulose acylate film. This resulted in the fabrication of a polarizing plate (P1) containing the optical film (1a-1b-1c) and a linear polarizer. The polarizing plate (P1) consisted of a polarizer protective film, a linear polarizer, an optically anisotropic layer (1a), an adhesive layer (2a), an optically anisotropic layer (1b), and an optically anisotropic layer (1c), laminated in this order. The angle between the absorption axis of the polarizer and the in-plane slow axis of the optically anisotropic layer (1a) was -76°. Furthermore, with the width direction as the reference 0°, the orientation axis angle of the liquid crystal compound on the optically anisotropic layer (1b) side was -14°, which coincided with the in-plane slow axis direction of the optically anisotropic layer (1a).

[0188] <Example 10> An optical film containing an optically anisotropic layer (3a) and an optical film containing an optically anisotropic layer (4a) were transported at a speed of 1 m / min from the optical film unwinding roller of Example 3 and the optical film unwinding roller of Example 4, respectively. The optically anisotropic layer (3a) and the optically anisotropic layer (4a) were positioned so that their surfaces were in contact with each other, and plasma was irradiated from the plasma irradiation device described below under the conditions described below towards the joint of the pressure roller to laminate a 3 nm silicon dioxide layer in each case. The pressure applied to the laminate by the pressure roller was set to 0.2 MPa.

[0189] - Plasma Irradiation Device - Atmospheric pressure plasma jet device (burette nozzle double-tube type) Double-tube structure: outer diameter of outer tube Φ15 mm, outer diameter of inner tube Φ8 mm Copper electrodes placed on the outside of the outer tube Peak voltage: 8 kV Pulse width: 5 microseconds Bipolar pulse: 10 kHz Gas flowing through the outer tube: Helium gas (plasma generation gas, flow rate: 10 L / min) Gas flowing through the inner tube: Tetraethoxysilane (flow rate: 5 mg / min), oxygen gas (flow rate: 100 mL / min), nitrogen gas (flow rate: 500 mL / min)

[0190] The cellulose acylate film in the optical film of Example 3 was peeled off, and the exposed surface was treated in the same manner as in Example 9, and then laminated with the optically anisotropic layer (1b-1c) prepared in Example 9. Furthermore, the same treatment as in Example 9 was performed, and the resulting laminate was laminated with a polarizer to produce a polarizing plate. In the polarizing plate, the polarizer protective film, PVA adhesive, polarizer, adhesive layer (2a), optically anisotropic layer (4a), optically anisotropic layer (3a), adhesive layer (2a), optically anisotropic layer (1b), and optically anisotropic layer (1c) were laminated in this order.

[0191] <Example 11> An optically anisotropic layer-forming composition (H) containing a rod-shaped liquid crystal compound of the following composition was applied to the cellulose acylate film prepared above 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, the film was heated at 60°C for 1 minute, and then the resulting composition layer was irradiated with 320 nm LED-UV (90 mJ / cm²) from the air interface side at 40°C under air (oxygen concentration approximately 21 vol%). ２ The lower layer was cured. Immediately after the lower layer cured (within 1 second of the lower layer curing), it was heated at 120°C for 1 minute. Then, UV irradiation (100 mJ / cm²) was performed at 120°C while purging with nitrogen to reduce the oxygen concentration to 1% or less. ２ The orientation of the liquid crystal compound was fixed by the following procedure to form an optically anisotropic layer (b) and obtain an optical film. The thickness of the formed optically anisotropic layer (b) was 0.6 μm. It was confirmed that the optically anisotropic layer (b) was composed of three layers exhibiting different optical anisotropies: a phase difference layer (positive C plate), an isotropic layer, and a gradient layer placed between the phase difference layer and the isotropic layer. The in-plane retardation of the phase difference layer at a wavelength of 550 nm was 0 nm, and the retardation in the thickness direction at a wavelength of 550 nm was -80 nm. The average inclination angle of the rod-shaped liquid crystal compound in the phase difference layer with respect to the film surface in the direction of the long axis was 90°, and it was confirmed that it was oriented perpendicular to the film surface. Using the film obtained above instead of the optical film of Example 3, and using the optical film of Example 5 instead of the optical film of Example 4, plasma treatment was performed according to the same procedure as in Example 10, the two films were laminated, and a polarizing plate was fabricated by referring to the procedure of Example 10. In the polarizing plate, the polarizer protective film, PVA adhesive, polarizer, adhesive layer (2a), optical anisotropy layer (5a), and optical anisotropy layer (b) were laminated in this order.

[0192] <Example 12> An optically anisotropic layer (8a) was fabricated on the positive C plate layer prepared in Example 9 using the same method as in Example 8. Next, the optically anisotropic layer (1a) from Example 1 and the optically anisotropic layer (8a) were bonded together via an adhesive, and a polarizing plate was fabricated using the same method as in Example 9. In the polarizing plate, the polarizer protective film, PVA adhesive, polarizer, adhesive layer (2a), optically anisotropic layer (1a), adhesive layer (2a), optically anisotropic layer (8a), and positive C plate were laminated in this order.

[0193] <Evaluation> (Color unevenness within the plane) Polarizing plates prepared in Examples 9 to 12 were laminated to black acrylic using a pressure-sensitive adhesive so that the polarizer protective film was on the surface side. Furthermore, a glass with an AR layer was laminated to the side opposite the black acrylic plate side of the resulting laminate using adhesive to obtain a sample. Under a rod-shaped fluorescent lamp (FPL-27EX-N), the sample was set with a diffuser plate at an azimuth angle where the long axis of the rod-shaped fluorescent lamp and the long direction of the polarizing plate were perpendicular, and the color within the plane was observed from an extreme angle of 30 to 40°. When setting the sample, the glass with the AR layer was set so that it was on the side of the fluorescent lamp. This allowed evaluation of color unevenness within the plane when viewed from an oblique direction. The evaluation criteria are as follows: A: Almost no color unevenness within the plane was visible. B: Only very slight color unevenness within the plane was visible. C: Slight color unevenness within the plane was visible, but there was no problem in use. D: Color unevenness was visible on the surface, but there was no problem in use. E: Color unevenness was strongly visible on the surface, which is a problem in use. F: Color unevenness was very strongly visible on the surface, which is a problem in use. The result for Example 9 was C, the result for Example 10 was D, the result for Example 11 was A, and the result for Example 12 was B.

[0194] (Color Azimuth Dependence) The polarizing plates prepared in Examples 9 to 12 were bonded to an image display element via a pressure-sensitive adhesive, with the polarizer protective film facing the surface. Furthermore, glass with an AR layer was bonded to the side of the resulting laminate opposite to the image display element via adhesive. The azimuth dependence of the color was checked when the display device was viewed from an oblique direction with a black display. The results were as follows, and all were at a level that did not pose a practical problem. Example 9: There was a slight change in color due to the azimuth angle, but it did not pose a problem for use. Example 10: There was a very slight change in color due to the azimuth angle, and it did not pose a problem for use. Example 11: There was a slight change in color due to the azimuth angle, but it did not pose a problem for use. Example 12: There was a slight change in color due to the azimuth angle, but it did not pose a problem for use.

[0195] 10 Film 12 Phase difference layer 14 Gradation layer 16 Isotropic layer 20 Support 22 Composition layer 22A Lower region 22B Upper region

Claims

1. A film having a phase difference layer, a gradient layer, and an isotropic layer in this order, wherein the phase difference layer and the gradient layer are arranged adjacent to each other, the gradient layer and the isotropic layer are arranged adjacent to each other, the phase difference layer, the gradient layer, and the isotropic layer all contain a liquid crystal compound, the gradient layer is a layer in which optical anisotropy decreases from the phase difference layer side toward the isotropic layer side, and the phase difference layer is an A plate, a C plate, or a liquid crystal layer in which the liquid crystal compound is twisted and oriented at a twist angle of 180° or less.

2. The film according to claim 1, wherein the thickness of the gradient layer is 0.1 μm or more.

3. The film according to claim 1, wherein the phase difference layer is a liquid crystal layer in which the A plate or the liquid crystal compound is twisted and oriented at a twist angle of 180° or less, and the gradation layer is a layer in which the birefringence Δn decreases from the phase difference layer side toward the isotropic layer side.

4. The film according to claim 1, wherein the phase difference layer is a C plate, and the gradation layer is a layer in which the absolute value of retardation in the thickness direction decreases from the phase difference layer side toward the isotropic layer side.

5. The film according to claim 1, further comprising an adjacent layer disposed adjacent to the isotropic layer on the opposite side from the gradation layer, wherein the difference between the refractive index of the isotropic layer on the adjacent layer side and the refractive index of the adjacent layer on the isotropic layer side is 0.11 or less.

6. A polarizing plate comprising a film according to any one of claims 1 to 4 and a polarizer.

7. A polarizing plate comprising the film described in claim 5 and a polarizer, wherein the difference between the refractive index of the isotropic layer on the adjacent layer side and the refractive index of the adjacent layer on the isotropic layer side in the transmission axis direction of the polarizer is 0.11 or less.

8. An image display device comprising an image display element and a polarizing plate as described in claim 6.

Images