Phase difference film, circular polarizer, display device

Abstract

To provide: a retardation film applied to an image display device as a circular polarization plate in combination with a polarizer and having a small variation in hue when observing the image display device at all azimuth angles from an oblique direction; a circular polarization plate; and an image display device.SOLUTION: A retardation film includes a first optical anisotropic layer, a second optical anisotropic layer, a third optical anisotropic layer and a fourth optical anisotropic layer in this order. The first optical anisotropic layer is a C plate; the second optical anisotropic layer is an A plate; the third optical anisotropic layer is a layer formed by fixing a liquid crystal compound twisted and oriented along a helical axis extended in the thickness direction; and the first optical anisotropic layer, the second optical anisotropic layer, the third optical anisotropic layer and the fourth optical anisotropic layer have predetermined constitutions.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a phase difference film, a circular polarizer, and a display device. [Background technology]

[0002] Phase difference films with refractive index anisotropy are applied to various uses, such as anti-reflective coatings for display devices and optical compensation films for liquid crystal display devices. For example, Patent Document 1 discloses a phase difference plate in which two optically anisotropic layers exhibiting predetermined optical properties are laminated. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 5960743 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] The present inventors applied an optical film with an optically anisotropic layer laminated as described in Patent Document 1 to a display device as a circular polarizer in combination with a polarizer, and confirmed that there was a significant change in color when the display device was observed from an oblique direction at all directional angles, indicating room for improvement.

[0005] In view of the above circumstances, the present invention aims to provide a phase difference film that, when applied to a display device as a circular polarizer in combination with a polarizer, exhibits minimal color change when the display device is observed from an oblique direction across all directional angles. Furthermore, the present invention aims to provide circular polarizing plates and display devices. [Means for solving the problem]

[0006] The inventors of this invention have diligently studied the problems of the prior art and have found that the above problems can be solved by the following configuration.

[0007] (1) Having a first optical anisotropy layer, a second optical anisotropy layer, a third optical anisotropy layer, and a fourth optical anisotropy layer in this order. The first optical anisotropy layer is a C plate. The second optical anisotropy layer is plate A, The third optical anisotropic layer is a layer in which a liquid crystal compound is fixed in a torsion orientation along a helical axis extending in the thickness direction. The fourth optical anisotropy layer is a C plate. If the first optical anisotropy layer is a negative C plate, the second optical anisotropy layer is a negative A plate, the liquid crystal compound of the third optical anisotropy layer is a rod-shaped liquid crystal compound, and the fourth optical anisotropy layer is a positive C plate. If the first optically anisotropic layer is a positive C plate, the second optically anisotropic layer is a positive A plate, the liquid crystal compound of the third optically anisotropic layer is a disc-shaped liquid crystal compound, and the fourth optically anisotropic layer is a negative C plate. A phase difference film in which the angle between the in-plane slow axis of the second optical anisotropy layer and the in-plane slow axis of the third optical anisotropy layer on the surface facing the second optical anisotropy layer is in the range of 0 to 30°. (2) The phase difference film according to (1), wherein the torsion angle of the liquid crystal compound is within the range of 80 ± 30°. (3) The phase difference film according to (1) or (2), wherein the absolute value of the retardation in the thickness direction at a wavelength of 550 nm of the first optical anisotropy layer is 5 to 100 nm. (4) A phase difference film according to any one of (1) to (3), wherein the in-plane retardation of the second optical anisotropy layer at a wavelength of 550 nm is 120 to 240 nm. (5) A phase difference film according to any of (1) to (4), wherein the product Δnd of the refractive index anisotropy Δn of the third optical anisotropy layer at a wavelength of 550 nm and the thickness d of the third optical anisotropy layer is 120 to 240 nm. (6) A phase difference film according to any one of (1) to (5), wherein the absolute value of the retardation in the thickness direction at a wavelength of 550 nm of the fourth optical anisotropy layer is 5 to 100 nm. (7) Having a first optical anisotropy layer, a second optical anisotropy layer, a third optical anisotropy layer, and a fourth optical anisotropy layer in this order, The first optical anisotropy layer and the second optical anisotropy layer are either in direct contact or laminated with an adhesion layer in between. The second optical anisotropy layer and the third optical anisotropy layer are either in direct contact or laminated with an adhesion layer in between. The third optical anisotropy layer and the fourth optical anisotropy layer are either in direct contact or laminated with an adhesion layer in between. A phase difference film that satisfies at least one of the requirements 1 to 4 described below. (8) Having a first optical anisotropy layer, a second optical anisotropy layer, a third optical anisotropy layer, and a fourth optical anisotropy layer in this order. The first optical anisotropy layer is a C plate. The second optical anisotropy layer is plate A, The third optical anisotropic layer is a layer in which a liquid crystal compound is fixed in a torsion orientation along a helical axis extending in the thickness direction. The fourth optical anisotropy layer is a C plate. At least one of the following is laminated with respect to an adhesion layer: a first optical anisotropy layer and a second optical anisotropy layer, a second optical anisotropy layer and a third optical anisotropy layer, and a third optical anisotropy layer and a fourth optical anisotropy layer. A phase difference film in which the difference between the average refractive index of the adhesion layer and the average refractive index of the optical anisotropy layer adjacent to the adhesion layer is 0.10 or less. (9) The second optical anisotropy layer and the third optical anisotropy layer are laminated with an adhesion layer in between. The difference between the average refractive index of the adhesion layer and the average refractive index of the second optical anisotropy layer is 0.08 or less. A phase difference film according to (7) or (8), wherein the difference between the average refractive index of the adhesion layer and the average refractive index of the third optical anisotropy layer is 0.08 or less. (10) A phase difference film as described in (8) that satisfies all of requirements 1 to 4 described below. (11) A circular polarizer comprising a polarizer and a phase difference film as described in any of (1) to (10). (12) A display device comprising a phase difference film as described in any of (1) to (10) or a circular polarizer as described in (11).

Advantages of the Invention

[0008] According to the present invention, a retardation film can be provided that, when applied to a display device as a circular polarizing plate in combination with a polarizer, exhibits little color change when the display device is observed from an oblique direction over an omnidirectional angle. Further, according to the present invention, a circular polarizing plate and a display device can also be provided.

Brief Description of the Drawings

[0009] [Figure 1] It is an example of a schematic cross-sectional view of the first embodiment of the retardation film of the present invention. [Figure 2] It is an example of a schematic cross-sectional view of the first embodiment of the circular polarizing plate of the present invention. [Figure 3] It is a diagram showing the relationship between the absorption axis of the polarizer and the in-plane slow axes of each of the second optically anisotropic layer and the third optically anisotropic layer in the first embodiment of the circular polarizing plate of the present invention. [Figure 4] It is a schematic diagram showing the angular relationship between the absorption axis of the polarizer and the in-plane slow axes of each of the second optically anisotropic layer and the third optically anisotropic layer when observed from the direction of the white arrow in FIG. 2. [Figure 5] It is an example of a schematic cross-sectional view of the second embodiment of the retardation film of the present invention. [Figure 6] It is an example of a schematic cross-sectional view of the second embodiment of the circular polarizing plate of the present invention. [Figure 7] It is a diagram showing the relationship between the absorption axis of the polarizer and the in-plane slow axes of each of the second optically anisotropic layer and the third optically anisotropic layer in the second embodiment of the circular polarizing plate of the present invention. [Figure 8] It is a schematic diagram showing the angular relationship between the absorption axis of the polarizer and the in-plane slow axes of each of the second optically anisotropic layer and the third optically anisotropic layer when observed from the direction of the white arrow in FIG. 6. [Figure 9] It is an example of a schematic cross-sectional view of the third embodiment of the retardation film of the present invention. [Figure 10] It is an example of a schematic cross-sectional view of the fourth embodiment of the retardation film of the present invention. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below. In this specification, numerical ranges represented by "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. Furthermore, unless otherwise specified, the in-plane slow-phase axis and in-plane fast-phase axis are defined at a wavelength of 550 nm. In other words, unless otherwise specified, for example, when referring to the in-plane slow-phase axis direction, it means the direction of the in-plane slow-phase axis at a wavelength of 550 nm.

[0011] In this invention, Re(λ) and Rth(λ) represent the in-plane retardation and thickness-direction 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 OPMF-1 (manufactured by OptoScience Co., Ltd.). By inputting the refractive index ((nx+ny+nz) / 3) and film thickness (d(μm)) into AxoScan, Slow axis direction (°) Re(λ)=R0(λ) Rth(λ)=((nx+ny) / 2-nz)×d This is calculated. Note that R0(λ) is a value displayed by the AxoScan OPMF-1, and it means Re(λ).

[0012] In this specification, the refractive index ((nx+ny+nz) / 3) is measured using an Abbe refractometer (NAR-4T, manufactured by Atago Co., Ltd.) with a sodium lamp (λ=589nm) as the light source. Furthermore, when measuring wavelength dependence, it can be measured using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in combination with an interference filter. In the case of liquid crystal compounds, the average refractive index can be measured by measuring a film fixed in an optically isotropic phase using this method. Additionally, values ​​from the Polymer Handbook (JOHN WILEY & SONS, INC.) and catalogs of various optical films can 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).

[0013] In this specification, plates A and C are defined as follows: There are two types of A plates: positive A plates and negative A plates. When the refractive index in the slow axis direction (the direction in which the refractive index is maximum within the plane) is nx, the refractive index in the direction perpendicular to the slow axis within the plane is ny, and the refractive index in the thickness direction is nz, a positive A plate satisfies the relationship in equation (A1), and a negative A plate satisfies the relationship in equation (A2). Note that a positive A plate has a positive Rth value, and a negative A plate has a negative Rth value. Formula (A1) nx>ny≒nz Formula (A2) ny <nx≒nz The above "≒" includes not only cases where the two are completely identical, but also cases where they are substantially identical. "Substantially identical" means, for example, that (ny-nz)×d (where d is the film thickness) is -10 to 10 nm, preferably -5 to 5 nm, and that (nx-nz)×d is -10 to 10 nm, preferably -5 to 5 nm, and that that is also included in "nx≒nz". There are two types of C plates: positive C plates and negative C plates. Positive C plates satisfy the relationship in equation (C1), and negative C plates satisfy the relationship in equation (C2). Note that positive C plates show a negative value for Rth, and negative C plates show a positive value for Rth. Formula (C1) nz>nx≒ny Formula (C2) nz <nx≒ny Furthermore, the above "≒" includes not only cases where the two are completely identical, but also cases where they are substantially identical. "Substantially identical" means, for example, that (nx-ny)×d (where d is the thickness of the film) is between 0 and 10 nm, preferably between 0 and 5 nm, which is included in "nx≒ny".

[0014] In this specification, the average refractive index of an optically anisotropic layer, such as a layer comprising an A plate, a C plate, and a liquid crystal compound fixed in a torsion orientation along a helical axis extending in the thickness direction, is defined as shown in equation (N1). In equation (N1), nx represents the refractive index in the slow axis direction within the layer plane (the direction in which the refractive index is maximum within the plane), as described above, and ny also represents the refractive index in the direction perpendicular to the slow axis within the plane, as described above. Equation (N1) (Average refractive index) = (nx + ny) / 2 Furthermore, the average refractive index of the adhesion layer is also calculated using the above formula (N1). Note that if the adhesion layer is optically isotropic, the refractive index in any direction within the plane of the adhesion layer is used as the average refractive index. The average refractive index mentioned above refers to the average refractive index at a wavelength of 550 nm. The average refractive index can be measured using a reflection spectrophotometer FE3000 (manufactured by Otsuka Electronics Co., Ltd.), as shown in the examples described later. Specifically, the reflection spectrum of the layer for which the refractive index is to be measured is measured using the reflection spectrophotometer FE3000, and the average refractive index can be calculated by applying the n-Cauchy dispersion formula to the obtained reflection spectrum.

[0015] Furthermore, in this specification, when we say "layer A and layer B are laminated with an adhesive layer in between," it means that the adhesive layer is in contact with both layers A and B, and that layers A and B are laminated together. In other words, one surface of the adhesive layer is in contact with layer A, and the other surface is in contact with layer B, with the adhesive layer positioned between layers A and B.

[0016] In this specification, "visible light" refers to light with a wavelength of 400 to 700 nm. "Ultraviolet light" refers to light with a wavelength of 10 nm or more and less than 400 nm. Furthermore, in this specification, "orthogonal" or "parallel" includes a range of error that is permissible in the art to which the present invention pertains. For example, this means being within a range of ±5° from the exact angle, and preferably the error from the exact angle is within a range of ±3°.

[0017] A key feature of the phase difference film of the present invention is that it uses a combination of predetermined optical anisotropic layers.

[0018] <First embodiment of phase difference film> Hereinafter, a first embodiment of the phase difference film of the present invention will be described with reference to the drawings. Figure 1 shows a schematic cross-sectional view of the first embodiment of the phase difference film of the present invention. The phase difference film 10A has a first optical anisotropy layer 12A, a second optical anisotropy layer 14A, a third optical anisotropy layer 16A, and a fourth optical anisotropy layer 18A in this order. The first optical anisotropy layer 12A is a negative C plate, the second optical anisotropy layer 14A is a negative A plate, the third optical anisotropy layer 16A is a layer in which rod-shaped liquid crystal compounds LC, which are twisted and oriented along a helical axis extending in the thickness direction, are fixed, and the fourth optical anisotropy layer 18A is a positive C plate. The in-plane slow axis of the second optical anisotropy layer 14A is parallel to the in-plane slow axis of the third optical anisotropy layer 16A on the surface facing the second optical anisotropy layer 14A. The following provides a detailed description of each layer.

[0019] (First optically anisotropic layer 12A) The first optically anisotropic layer 12A is a negative C plate. The retardation in the thickness direction of the first optical anisotropy layer 12A at a wavelength of 550 nm is not particularly limited, but when the phase difference film of the present invention is applied to a display device as a circular polarizer in combination with a polarizer, and the display device is observed from an oblique direction at all directional angles, the change in color is smaller (hereinafter also referred to simply as "the effect of the present invention is better"), so 5 to 100 nm is preferred, and 10 to 90 nm is more preferred.

[0020] The first optical anisotropy layer 12A is not particularly limited in its composition as long as it is a negative C plate, and examples include a layer in which horizontally oriented disc-shaped liquid crystal compounds are fixed, and a resin film. Furthermore, the state in which the disc-shaped liquid crystal compound is horizontally oriented means that the disc surface of the disc-shaped liquid crystal compound and the main surface of the layer are parallel. However, strict parallelism is not required; it is preferable that the angle between the disc surface and the main surface of the layer is in the range of 0 ± 20°, and preferably in the range of 0 ± 10°. In this specification, the term "fixed" refers to a state in which the orientation of the liquid crystal compound is maintained. Specifically, it is preferable that the layer is non-fluid and that the fixed orientation can be stably maintained without causing changes in the orientation due to external fields or forces, typically in a temperature range of 0 to 50°C, or -30 to 70°C under more severe conditions.

[0021] Known compounds can be used as the disc-shaped liquid crystal compound. Examples of disc-shaped liquid crystal compounds include those described in paragraphs 0020 to 0067 of Japanese Patent Publication No. 2007-108732 and paragraphs 0013 to 0108 of Japanese Patent Publication No. 2010-244038.

[0022] The disc-shaped liquid crystal compound may have polymerizable groups. In this specification, the type of polymerizable group is not particularly limited, but functional groups capable of addition polymerization are preferred, polymerizable ethylenically unsaturated groups or cyclic polymerizable groups are more preferred, and (meth)acryloyl groups, vinyl groups, styryl groups, or allyl groups are even more preferred.

[0023] The type of resin that makes up the resin film is not particularly limited, but TAC (triacetylcellulose) is one example.

[0024] The first optically anisotropic layer 12A is preferably a layer formed by fixing horizontally oriented, polymerizable, disc-shaped liquid crystal compounds by polymerization.

[0025] The thickness of the first optical anisotropy layer 12A is not particularly limited. When the first optical anisotropy layer 12A is a layer in which horizontally oriented disc-shaped liquid crystal compounds are fixed, the thickness is preferably 10 μm or less, more preferably 0.1 to 5.0 μm, and even more preferably 0.3 to 2.0 μm. When the first optical anisotropy layer 12A is a resin film, the thickness of the first optical anisotropy layer 12A is preferably 10 to 100 μm, and more preferably 15 to 90 μm. Note that the thickness of the first optical anisotropy layer 12A refers to the average thickness of the first optical anisotropy layer 12A. The above average thickness is obtained by measuring the thickness of any five or more points on the first optical anisotropy layer 12A and taking the arithmetic mean of them.

[0026] (Second optical anisotropy layer 14A) The second optically anisotropic layer 14A is a negative A plate. The in-plane retardation of the second optical anisotropy layer 14A at a wavelength of 550 nm is not particularly limited, but 120 to 240 nm is preferred, and 130 to 230 nm is more preferred, in terms of achieving superior effects of the present invention. The retardation in the thickness direction of the second optical anisotropy layer 14A at a wavelength of 550 nm is not particularly limited, but -120 to -60 nm is preferred, and -115 to -65 nm is more preferred, in terms of achieving superior effects of the present invention.

[0027] The second optical anisotropy layer 14A may exhibit forward dispersiveness (a characteristic in which in-plane retardation decreases as the measurement wavelength increases) or inverse dispersiveness (a characteristic in which in-plane retardation increases as the measurement wavelength increases). It is preferable that the above-mentioned forward and inverse dispersiveness be exhibited in the visible light range.

[0028] The second optical anisotropy layer 14A is not particularly limited in its composition as long as it is a negative A plate. Examples include a layer formed by fixing a disc-shaped liquid crystal compound that is vertically oriented and whose optical axes (axes perpendicular to the disc surface) are aligned in the same direction, and a stretched film. In terms of superior effects of the present invention, a layer formed by fixing a disc-shaped liquid crystal compound that is vertically oriented and whose optical axes (axes perpendicular to the disc surface) are aligned in the same direction is preferred. The state in which the disc-shaped liquid crystal compound is vertically oriented means that the disc surface of the disc-shaped liquid crystal compound is parallel to the thickness direction of the layer. However, it is not required that they be strictly parallel; it is preferable that the angle between the disc surface and the thickness direction of the layer is in the range of 0 ± 20°, and preferably in the range of 0 ± 10°. Furthermore, the state in which the optical axes (axes perpendicular to the disk surface) of a disc-shaped liquid crystal compound are aligned in the same direction does not require them to be strictly in the same direction, but rather means that when the orientation of the slow axis is measured at any 20 positions in the plane, the maximum difference in the orientations of the slow axis among the 20 slow axis orientations (the difference between the two slow axis orientations with the largest difference among the 20 slow axis orientations) is less than 10°. Examples of disc-shaped liquid crystal compounds include the disc-shaped liquid crystal compound exemplified in the first optical anisotropy layer 12A. The disc-shaped liquid crystal compound may have polymerizable groups. The types of polymerizable groups that the disc-shaped liquid crystal compound may have are as described above.

[0029] The second optically anisotropic layer 14A is preferably a layer formed by fixing a disc-shaped liquid crystal compound having polymerizable groups through polymerization.

[0030] The thickness of the second optical anisotropy layer 14A 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. Note that the thickness of the second optical anisotropy layer 14A refers to the average thickness of the second optical anisotropy layer 14A. The above average thickness is obtained by measuring the thickness of any five or more points on the second optical anisotropy layer 14A and taking the arithmetic mean of them.

[0031] (Third optical anisotropy layer 16A) The third optically anisotropic layer 16A is a layer formed by fixing rod-shaped liquid crystal compounds LC that are twisted and oriented along a helical axis extending in the thickness direction. The third optical anisotropic layer 16A is preferably a layer formed by fixing a chiral nematic phase having a so-called helical structure. When forming the third optical anisotropic layer 16A, it is preferable to use at least a rod-shaped liquid crystal compound and a chiral agent described later.

[0032] The twist angle of the rod-shaped liquid crystal compound (the twist angle in the orientation direction of the liquid crystal compound) is not particularly limited and is often greater than 0° and less than or equal to 360°. However, a range of 80±30° (50~110°) is preferred, and a range of 80±20° (60~100°) is more preferred, in terms of achieving superior effects of the present invention. The torsional angle will be measured using Axometrics' AxoScan (polarimeter) device and their device analysis software. Furthermore, the twisted orientation of the rod-shaped liquid crystal compound means that the rod-shaped liquid crystal compound twists from one main surface to the other main surface of the third optical anisotropy layer 16A, with the thickness direction of the third optical anisotropy layer 16A as the axis. Consequently, the orientation direction (in-plane slow phase axis direction) of the rod-shaped liquid crystal compound differs depending on its position in the thickness direction of the third optical anisotropy layer 16A. In the torsional orientation, the long axis of the rod-shaped liquid crystal compound is positioned parallel to the main surface of the third optical anisotropy layer 16A. However, strict parallelism is not required; the angle between the long axis of the rod-shaped liquid crystal compound and the main surface of the third optical anisotropy layer 16A is preferably in the range of 0 ± 20°, and preferably in the range of 0 ± 10°.

[0033] The value of the product Δnd, which is the refractive index anisotropy Δn of the third optical anisotropy layer 16A at a wavelength of 550 nm and the thickness d of the third optical anisotropy layer 16A, is not particularly limited. However, 120 to 240 nm is preferred, and 130 to 230 nm is more preferred, in terms of achieving superior effects of the present invention. The above Δnd measurement method uses Axometrics' AxoScan (polarimeter) device and their device analysis software.

[0034] The angle between the in-plane slow axis of the second optical anisotropy layer 14A and the in-plane slow axis of the third optical anisotropy layer 16A on the surface facing the second optical anisotropy layer 14A is in the range of 0 to 30°, and preferably in the range of 0 to 20°.

[0035] The type of rod-shaped liquid crystal compound used to form the third optical anisotropy layer 16A is not particularly limited, and known compounds can be used. Examples of rod-shaped liquid crystal compounds include 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. The rod-shaped liquid crystal compound may have polymerizable groups. The types of polymerizable groups that the rod-shaped liquid crystal compound may have are as described above.

[0036] The third optically anisotropic layer 16A is preferably a layer formed by fixing a rod-shaped liquid crystal compound having polymerizable groups by polymerization. More specifically, it is more preferable that the layer is formed by fixing a rod-shaped liquid crystal compound having twistedly oriented polymerizable groups by polymerization.

[0037] The thickness of the third optical anisotropy layer 16A 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. Note that the thickness of the third optical anisotropy layer 16A refers to the average thickness of the third optical anisotropy layer 16A. The above average thickness is obtained by measuring the thickness of any five or more points on the third optical anisotropy layer 16A and taking their arithmetic mean.

[0038] (Fourth optical anisotropy layer 18A) The fourth optical anisotropy layer 18A is a positive C plate. The retardation in the thickness direction of the fourth optical anisotropy layer 18A at a wavelength of 550 nm is not particularly limited, but -100 to -5 nm is preferred, and -100 to -30 nm is more preferred, in terms of achieving superior effects of the present invention.

[0039] The fourth optical anisotropy layer 18A is not particularly limited in its composition as long as it is a positive C plate, and examples include a layer on which vertically oriented rod-shaped liquid crystal compounds are fixed, and a resin film. A layer on which vertically oriented rod-shaped liquid crystal compounds are fixed is preferred in that it provides superior effects of the present invention. The state in which the rod-shaped liquid crystal compound is vertically oriented means that the long axis of the rod-shaped liquid crystal compound is parallel to the thickness direction of the fourth optical anisotropy layer 18A. However, strict parallelism is not required; it is preferable that the angle between the long axis of the rod-shaped liquid crystal compound and the thickness direction of the fourth optical anisotropy layer 18A is in the range of 0 ± 20°, and preferably in the range of 0 ± 10°.

[0040] As the rod-shaped liquid crystal compound, known compounds can be used. Examples of rod-shaped liquid crystal compounds include the rod-shaped liquid crystal compound exemplified in the third optical anisotropy layer 16A. The rod-shaped liquid crystal compound may have polymerizable groups. The types of polymerizable groups that the rod-shaped liquid crystal compound may have are as described above.

[0041] The fourth optical anisotropic layer 18A is preferably a layer formed by fixing vertically oriented rod-shaped liquid crystal compounds having polymerizable groups by polymerization.

[0042] The thickness of the fourth optical anisotropy layer 18A 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. Note that the thickness of the fourth optical anisotropy layer 18A refers to the average thickness of the fourth optical anisotropy layer 18A. The above average thickness is obtained by measuring the thickness of any five or more points on the fourth optical anisotropy layer 18A and taking their arithmetic mean.

[0043] (Other components) The phase difference film 10A may include other components besides the first optical anisotropy layer 12A to the fourth optical anisotropy layer 18A described above.

[0044] (Intense layer) The phase difference film 10A may have an adhesion layer between each optically anisotropic layer. Examples of adhesion layers include known adhesive layers and bonding layers.

[0045] As described in Japanese Patent Publication No. 11-149015, generally, it is preferable to adjust the refractive index of each layer (e.g., optical anisotropy layer) forming the phase difference film from the viewpoint of suppressing reflection. The refractive index difference with respect to the bonded object is preferably 0.1 or less, more preferably 0.08 or less, even more preferably 0.06 or less, and particularly preferably 0.03 or less. Furthermore, the thickness of the adhesion layer is preferably 0.1 to 50 μm. From the viewpoint of thinning the layer, 25 μm or less is more preferable, 15 μm or less is even more preferable, and 5 μm or less is particularly preferable. From the viewpoint of suppressing interference unevenness, 5 μm or more is more preferable, 15 μm or more is even more preferable, and 25 μm or more is particularly preferable.

[0046] When an adhesion layer is placed between layers of an optically anisotropic layer formed by fixing liquid crystal compounds, a high-refractive-index adhesive or tack may be used. To increase the refractive index, it is also preferable to use high-refractive-index monomers or high-refractive-index metal nanoparticles. As high-refractive-index monomers, those having a benzene ring skeleton in the molecule are preferable. Examples of monofunctional monomers having a benzene ring skeleton in their molecules include ethoxylated O-phenylphenol (meth)acrylate, O-phenylphenol glycidyl ether (meth)acrylate, paracumylphenoxyethylene glycol (meth)acrylate, 2-methacryloyloxyethyl phthalate, 2-acryloyloxyethyl phthalate, 2-acryloyloxyethyl-2-hydroxyethyl phthalate, 2-acryloyloxypropyl phthalate, phenoxyethyl (meth)acrylate, EO-modified phenol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, EO-modified nonylphenol (meth)acrylate, PO-modified nonylphenol (meth)acrylate, phenylglycidyl ether (meth)acrylate, neopentyl glycol benzoate (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, ECH-modified phenoxy(meth)acrylate, benzyl (meth)acrylate, and vinylcarbazole. Examples of high refractive index metal nanoparticles include inorganic particles. Components of inorganic particles include metal oxides, metal nitrides, metal oxynitrides, and elemental metals. Examples of metal atoms contained in the above-mentioned metal oxides, metal nitrides, metal oxynitrides, and elemental metals include titanium atoms, silicon atoms, aluminum atoms, cobalt atoms, and zirconium atoms. Specific examples of inorganic particles include alumina particles, alumina hydrate particles, silica particles, zirconia particles, and inorganic oxide particles such as clay minerals (e.g., smectite). From the viewpoint of refractive index, zirconium oxide particles are preferred. The refractive index can be adjusted to a predetermined value by changing the amount of inorganic particles. The average particle size of the inorganic particles is not particularly limited, but when zirconium oxide is used as the main component, it is preferably 1 to 120 nm, more preferably 1 to 60 nm, and even more preferably 2 to 40 nm.

[0047] (Orientation film) The phase difference film 10A may further have an alignment layer. The alignment layer may be arranged between each optical anisotropy layer. Furthermore, as shown in Figure 1, it is preferable that the phase difference film 10A does not have alignment films between each optical anisotropic layer.

[0048] The oriented film can be formed by means such as rubbing of an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having microgrooves, or accumulation of an organic compound (e.g., ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearylate) by the Langmuir-Bludget method (LB film). Furthermore, orientation films are known in which orientation functions are generated by the application of an electric field, a magnetic field, or light irradiation (preferably polarized light). The orientation film is preferably formed by a polymer rubbing treatment. Photo-alignment films can also be considered as alignment films. The thickness of the orientation film is not particularly limited as long as it can perform the orientation function, but it is preferably 0.01 to 5.0 μm, more preferably 0.05 to 2.0 μm, and even more preferably 0.1 to 0.5 μm.

[0049] (substrate) The phase difference film 10A may further include a substrate. A transparent substrate is preferred as the substrate. A transparent substrate is defined as a substrate with a visible light transmittance of 60% or more, preferably 80% or more, and more preferably 90% or more. The thickness of the substrate is not particularly limited, but is preferably 10 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 90 μm.

[0050] Furthermore, the substrate may consist of multiple layers stacked together. To improve adhesion between the substrate and the layer placed on top of it, the substrate surface may be subjected to surface treatment (for example, glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment). Alternatively, an adhesive layer (primer layer) may be provided on the substrate. The substrate may be a so-called temporary support. For example, after manufacturing an optically anisotropic layer on the substrate, the substrate may be peeled off from the optically anisotropic layer as needed.

[0051] (Method of manufacturing phase difference film) The method for manufacturing the phase difference film is not particularly limited, and known methods can be used. For example, a phase difference film can be manufactured by creating first to fourth optical anisotropy layers and bonding them together in a predetermined order via an adhesion layer (e.g., an adhesive layer or bonding agent layer). Furthermore, the first to fourth optically anisotropic layers can each be produced using an optically anisotropic layer-forming composition containing a polymerizable liquid crystal compound.

[0052] The following describes in detail a method for producing optically anisotropic layers (first to fourth optically anisotropic layers) using an optically anisotropic layer-forming composition containing a liquid crystal compound having polymerizable groups.

[0053] The polymerizable liquid crystal compound (hereinafter also referred to as "polymerizable liquid crystal compound") contained in the composition for forming an optically anisotropic layer is as described above. As described above, rod-shaped liquid crystal compounds and disc-shaped liquid crystal compounds are appropriately selected depending on the characteristics of the optically anisotropic layer formed. The content of polymerizable liquid crystal compounds in the optical anisotropic layer-forming composition is preferably 60 to 99% by mass, and more preferably 70 to 98% by mass, based on the total solid content of the optical anisotropic layer-forming composition. The term "solid content" refers to the components that can form an optically anisotropic layer after the solvent has been removed, and is considered solid content even if its state is liquid.

[0054] The composition for forming an optically anisotropic layer may contain compounds other than liquid crystal compounds having polymerizable groups. For example, the optical anisotropy layer forming composition for forming the third optical anisotropy layer 16A preferably contains a chiral agent in order to twist-orient the liquid crystal compound. The chiral agent is added to twist-orient the liquid crystal compound, but of course, if the liquid crystal compound is an optically active compound, such as having an asymmetric carbon in its molecule, the addition of a chiral agent is unnecessary. Furthermore, depending on the manufacturing method and the twist angle, the addition of a chiral agent may not be necessary. As for the chiral agent, there are no particular structural restrictions as long as it is compatible with the liquid crystal compound used in combination. Any known chiral agent (for example, described in "Liquid Crystal Device Handbook" edited by the 142nd Committee of the Japan Society for the Promotion of Science, Chapter 3, Section 4-3, Chiral Agents for TN and STN, p. 199, 1989) can be used. The amount of chiral agent used is not particularly limited and is adjusted to achieve the aforementioned twist angle.

[0055] The composition for forming an optically anisotropic layer may contain a polymerization initiator. The polymerization initiator used is selected according to the type of polymerization reaction, and examples include thermal polymerization initiators and photopolymerization initiators. The content of the polymerization initiator in the optically anisotropic layer-forming composition is preferably 0.01 to 20% by mass, and more preferably 0.5 to 10% by mass, based on the total solid content of the optically anisotropic layer-forming composition.

[0056] Other components that may be included in the optically anisotropic layer-forming composition include, in addition to those mentioned above, polyfunctional monomers, orientation control agents (vertical orientation agents, horizontal orientation agents), surfactants, adhesion improvers, plasticizers, and solvents.

[0057] Methods for applying compositions for forming optically anisotropic layers include curtain coating, dip coating, spin coating, printing coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, and wire bar coating.

[0058] Next, the formed coating film is subjected to an orientation treatment to orient the polymerizable liquid crystal compounds within the coating film. For example, when forming the first optical anisotropy layer 12A, the disc-shaped liquid crystal compounds are oriented horizontally. When forming the second optical anisotropy layer 14A, the disc-shaped liquid crystal compounds are oriented vertically, so that the optical axes (axes perpendicular to the disc surface) of the disc-shaped liquid crystal compounds are aligned in the same direction. When forming the third optical anisotropy layer 16A, the rod-shaped liquid crystal compounds are oriented in a twisted manner. When forming the fourth optical anisotropy layer 18A, the rod-shaped liquid crystal compounds are oriented vertically.

[0059] Orientation treatment can be performed by drying the coating film at room temperature or by heating the coating film. In the case of thermotropic liquid crystal compounds, the liquid crystal phase formed by orientation treatment can generally be shifted by changes in temperature or pressure. In the case of lyotropic liquid crystal compounds, the phase can also be shifted by changes in the composition ratio, such as the amount of solvent. The conditions for heating the coating film are not particularly limited, but the heating temperature is preferably 50 to 250°C, more preferably 50 to 150°C, and the heating time is preferably 10 seconds to 10 minutes. Furthermore, after heating the coating film, it may be cooled as needed before the curing treatment (light irradiation treatment) described later.

[0060] Next, the coating film in which the polymerizable liquid crystal compound is oriented is subjected to a curing treatment. The curing treatment method applied to a coating film on which polymerizable liquid crystal compounds are oriented is not particularly limited and includes, for example, light irradiation treatment and heat treatment. Among these, light irradiation treatment is preferred from the viewpoint of manufacturability, and ultraviolet irradiation treatment is more preferred. There are no particular restrictions on the irradiation conditions for the light irradiation treatment, but 50-1000 mJ / cm² is recommended. 2 A certain irradiation dose is preferred. The atmosphere during the light irradiation treatment is not particularly limited, but a nitrogen atmosphere is preferred.

[0061] <First embodiment of a circular polarizing plate> The first embodiment of the phase difference film of the present invention can be used as a circular polarizer in combination with a polarizer. A circular polarizer is an optical element that converts unpolarized light into circularly polarized light. The circular polarizing plate of the present invention having the above configuration is suitably used for anti-reflective applications in display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescent displays (ELDs), and cathode ray tube displays (CRTs).

[0062] 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 can be used. There are no particular restrictions on the type of polarizer; commonly used polarizers can be used, such as iodine-based polarizers, dye-based polarizers utilizing dichroic substances, and polyene-based polarizers. Iodine-based and dye-based polarizers are generally manufactured by adsorbing iodine or a dichroic dye onto polyvinyl alcohol and then stretching the material. A protective film may be placed on one or both sides of the polarizer.

[0063] Figure 2 shows a schematic cross-sectional view of one embodiment of the circular polarizer 100A. Figure 3 shows the relationship between the absorption axis of the polarizer 20 and the in-plane slow axis of the second optical anisotropy layer 14A and the third optical anisotropy layer 16A in the circular polarizer 100A shown in Figure 2. In Figure 3, the arrow in the polarizer 20 represents the absorption axis, and the arrows in the second optical anisotropy layer 14A and the third optical anisotropy layer 16A represent the in-plane slow axis in each layer. Figure 4 shows the relationship between the angle between the absorption axis of the polarizer 20 (dashed line) and the in-plane slow phase axes (solid lines) of the second optical anisotropy layer 14A and the third optical anisotropy layer 16A, respectively, as observed from the white arrow in Figure 2. The rotation angle of the in-plane slow axis is expressed as a positive angle for counterclockwise rotation and a negative angle for clockwise rotation, based on the absorption axis of the polarizer 20 (0°) when observed from the white arrow in Figure 2. The torsional direction of the liquid crystal compound is determined as either right-handed (clockwise) or left-handed (counterclockwise) torsion, based on the in-plane slow axis on the front surface (opposite side from the polarizer 20) of the third optical anisotropy layer 16A when observed from the white arrow in Figure 2.

[0064] As shown in Figure 2, the circular polarizer 100A includes a polarizer 20, a first optical anisotropy layer 12A, a second optical anisotropy layer 14A, a third optical anisotropy layer 16A, and a fourth optical anisotropy layer 18A in that order. As shown in Figures 3-4, the angle φa1 between the absorption axis of the polarizer 20 and the in-plane slow axis of the second optical anisotropy layer 14A is 75°. More specifically, the in-plane slow axis of the second optical anisotropy layer 14A is rotated by -75° (75° clockwise) with respect to the absorption axis of the polarizer 20. Although Figures 3-4 show an embodiment where the in-plane slow axis of the second optical anisotropy layer 14A is at -75°, the present invention is not limited to this embodiment, and it is preferable that it be within the range of -75±13°. In other words, it is preferable that the angle between the absorption axis of the polarizer 20 and the in-plane slow axis of the second optical anisotropy layer 14A is within the range of 75±13°. As shown in Figure 3, within the second optical anisotropy layer 14A, the in-plane slow axis at the polarizer 20 side surface 141A of the second optical anisotropy layer 14A is parallel to the in-plane slow axis at the third optical anisotropy layer 16A side surface 142A of the second optical anisotropy layer 14A.

[0065] As shown in Figures 3-4, the in-plane slow axis of the second optical anisotropy layer 14A and the in-plane slow axis of the third optical anisotropy layer 16A on the surface 161A facing the second optical anisotropy layer 14A are parallel. In Figures 3-4, the in-plane slow axis of the second optical anisotropy layer 14A and the in-plane slow axis of the third optical anisotropy layer 16A on the second optical anisotropy layer 14A side surface 161A are shown to be parallel. However, the present invention is not limited to this embodiment, and the angle between the in-plane slow axis of the second optical anisotropy layer 14A and the in-plane slow axis of the third optical anisotropy layer 16A on the second optical anisotropy layer 14A side surface 161A may be within the range of 0 to 30°. Therefore, for example, when observed from the white arrow in Figure 2, the in-plane slow axis of the third optical anisotropy layer 16A on the second optical anisotropy layer 14A side surface 161A may be positioned 30° clockwise or 30° counterclockwise, relative to the in-plane slow axis of the second optical anisotropy layer 14A. As described above, the third optical anisotropy layer 16A is a layer in which rod-shaped liquid crystal compounds are fixed, twisted along a helical axis extending in the thickness direction. Therefore, as shown in Figures 3-4, the in-plane slow axis at the surface 161A of the third optical anisotropy layer 16A on the side of the second optical anisotropy layer 14A and the in-plane slow axis at the surface 162A of the third optical anisotropy layer 16A opposite to the side of the second optical anisotropy layer 14A form the twist angle described above (80° in Figure 3). In other words, the angle φa2 between the in-plane slow axis at the surface 161A of the third optical anisotropy layer 16A on the side of the second optical anisotropy layer 14A and the in-plane slow axis at the surface 162A opposite to the side of the second optical anisotropy layer 14A is 80°. More specifically, the torsion direction of the rod-shaped liquid crystal compound in the third optical anisotropy layer 16A is right-handed (clockwise), and the torsion angle is 80°. Therefore, the angle between the absorption axis of the polarizer 20 and the in-plane slow phase axis on the surface 162A of the third optical anisotropy layer 16A opposite to the second optical anisotropy layer 14A is 5°. In Figures 3 and 4, the twist angle of the rod-shaped liquid crystal compound in the third optical anisotropy layer 16A is shown to be 80°, but the invention is not limited to this embodiment, and it is preferable that the twist angle of the rod-shaped liquid crystal compound be within the range of 80 ± 30°. In other words, it is preferable that the angle between the in-plane slow axis on the surface 161A of the third optical anisotropy layer 16A on the side of the second optical anisotropy layer 14A and the in-plane slow axis on the surface 162A of the third optical anisotropy layer 16A on the opposite side of the second optical anisotropy layer 14A is within the range of 80 ± 30°.

[0066] As described above, in the embodiments shown in Figures 3-4, when the circular polarizer 100A is observed from the phase difference film 10A side, the in-plane slow phase axis of the second optical anisotropy layer 14A is rotated 75° clockwise with respect to the absorption axis of the polarizer 20, and the twist direction of the rod-shaped liquid crystal compound in the third optical anisotropy layer 16A is clockwise (right-handed twist). Figures 3-4 detail the configuration in which the twist direction of the rod-shaped liquid crystal compound is clockwise, but a counterclockwise configuration is also possible as long as the predetermined angular relationship is satisfied. More specifically, when the circular polarizer 100A is observed from the phase difference film 10A side, the in-plane slow axis of the second optical anisotropy layer 14A is rotated counterclockwise by 75° with respect to the absorption axis of the polarizer 20, and the twist direction of the rod-shaped liquid crystal compound in the third optical anisotropy layer 16A is counterclockwise (left-handed twist).

[0067] In other words, in a circular polarizer including the first embodiment of the phase difference film, when the circular polarizer is observed from the phase difference film side, if the in-plane slow axis of the second optical anisotropy layer rotates clockwise within a range of 75±13° (preferably 75±10°) with respect to the absorption axis of the polarizer, it is preferable that the twisting direction of the rod-shaped liquid crystal compound in the third optical anisotropy layer is clockwise with respect to the in-plane slow axis on the surface of the third optical anisotropy layer on the fourth optical anisotropy layer side. Furthermore, in a circular polarizer including the first embodiment of the phase difference film, when the circular polarizer is observed from the phase difference film side, if the in-plane slow axis of the second optical anisotropy layer rotates counterclockwise within a range of 75±13° (preferably 75±10°) with respect to the absorption axis of the polarizer, it is preferable that the twisting direction of the rod-shaped liquid crystal compound in the third optical anisotropy layer is counterclockwise with respect to the in-plane slow axis on the surface of the third optical anisotropy layer on the fourth optical anisotropy layer side.

[0068] The above circular polarizer may have other components besides the phase difference film and polarizer. A circular polarizer may have an adhesion layer between the phase difference film and the polarizer. Examples of adhesion layers include the known adhesive layers and bonding layers mentioned above.

[0069] The method for manufacturing the circular polarizer described above is not particularly limited and includes known methods. For example, one method involves bonding a polarizer and a phase difference film via an adhesion layer.

[0070] <Second embodiment of phase difference film> A second embodiment of the phase difference film of the present invention will be described below with reference to the drawings. Figure 5 shows a schematic cross-sectional view of the second embodiment of the phase difference film of the present invention. The phase difference film 10B has a first optical anisotropy layer 12B, a second optical anisotropy layer 14B, a third optical anisotropy layer 16B, and a fourth optical anisotropy layer 18B in this order. The first optical anisotropy layer 12B is a positive C plate, the second optical anisotropy layer 14B is a positive A plate, the third optical anisotropy layer 16B is a layer in which a disc-shaped liquid crystal compound LC, twisted and oriented along a helical axis extending in the thickness direction, is fixed, and the fourth optical anisotropy layer 18B is a negative C plate. The following provides a detailed description of each layer.

[0071] (First optical anisotropy layer 12B) The first optically anisotropic layer 12B is a positive C plate. The retardation in the thickness direction of the first optical anisotropy layer 12B at a wavelength of 550 nm is not particularly limited, but -100 to -5 nm is preferred, and -90 to -10 nm is more preferred, in terms of achieving superior effects of the present invention.

[0072] The first optical anisotropy layer 12B is not particularly limited in its composition as long as it is a positive C plate, and examples include a layer on which vertically oriented rod-shaped liquid crystal compounds are fixed, and a resin film. A layer on which vertically oriented rod-shaped liquid crystal compounds are fixed is preferred in that it provides superior effects of the present invention. The state in which the rod-shaped liquid crystal compound is vertically oriented means that the long axis of the rod-shaped liquid crystal compound is parallel to the thickness direction of the first optical anisotropy layer 12B. However, strict parallelism is not required; it is preferable that the angle between the long axis of the rod-shaped liquid crystal compound and the thickness direction of the first optical anisotropy layer 12B is in the range of 0 ± 20°, and preferably within the range of 0 ± 10°.

[0073] As the rod-shaped liquid crystal compound, known compounds can be used. Specific examples of rod-shaped liquid crystal compounds are as described in the first embodiment of the phase difference film. The rod-shaped liquid crystal compound may have polymerizable groups. The types of polymerizable groups that the rod-shaped liquid crystal compound may have are as described above.

[0074] The first optically anisotropic layer 12B is preferably a layer formed by fixing vertically oriented rod-shaped liquid crystal compounds having polymerizable groups by polymerization.

[0075] The thickness of the first optical anisotropy layer 12B 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. Note that the thickness of the first optical anisotropy layer 12B refers to the average thickness of the first optical anisotropy layer 12B. The above average thickness is obtained by measuring the thickness of any five or more points on the first optical anisotropy layer 12B and taking the arithmetic mean of them.

[0076] (Second optical anisotropy layer) The second optically anisotropic layer 14B is a positive A plate. The in-plane retardation of the second optical anisotropy layer 14B at a wavelength of 550 nm is not particularly limited, but 120 to 240 nm is preferred, and 130 to 230 nm is more preferred, in terms of achieving superior effects of the present invention. The retardation in the thickness direction of the second optical anisotropy layer 14B at a wavelength of 550 nm is not particularly limited, but 60 to 120 nm is preferred, and 65 to 115 nm is more preferred, in terms of achieving superior effects of the present invention.

[0077] The second optical anisotropy layer 14B may exhibit forward dispersiveness (a characteristic in which in-plane retardation decreases as the measurement wavelength increases) or inverse dispersiveness (a characteristic in which in-plane retardation increases as the measurement wavelength increases). It is preferable that the above-mentioned forward and inverse dispersiveness are exhibited in the visible light range.

[0078] The second optical anisotropic layer 14B is not particularly limited in its composition as long as it is a positive A plate, and examples include a layer on which homogeneously oriented rod-shaped liquid crystal compounds are fixed, and a stretched film. A layer on which homogeneously oriented rod-shaped liquid crystal compounds are fixed is preferred in that it exhibits superior effects of the present invention. In this specification, homogeneous orientation refers to a state in which the molecular axes of a liquid crystal compound (for example, the long axis in the case of a rod-shaped liquid crystal compound) are aligned horizontally and in the same direction with respect to the layer surface (optical uniaxiality). Here, "horizontal" does not require strict horizontal alignment, but rather means an orientation in which the average molecular axis of the liquid crystal compound makes an inclination angle of less than 20° with respect to the main surface of the layer. Furthermore, "same orientation" does not require that the orientations be strictly the same, but rather means that when the orientation of the lagging axis is measured at any 20 locations in the plane, the maximum difference between the lagging axis orientations at those 20 locations (the difference between the two lagging axis orientations with the largest difference out of the 20 lagging axis orientations) is less than 10°. Specific examples of rod-shaped liquid crystal compounds are as described in the first embodiment of the phase difference film. The rod-shaped liquid crystal compound may have polymerizable groups. The types of polymerizable groups that the rod-shaped liquid crystal compound may have are as described above.

[0079] The second optically anisotropic layer 14B is preferably a layer formed by fixing a rod-shaped liquid crystal compound having polymerizable groups by polymerization.

[0080] The thickness of the second optical anisotropy layer 14B 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. Note that the thickness of the second optical anisotropy layer 14B refers to the average thickness of the second optical anisotropy layer 14B. The above average thickness is obtained by measuring the thickness of any five or more points on the second optical anisotropy layer 14B and taking the arithmetic mean of these measurements.

[0081] (Third optical anisotropy layer 16B) The third optically anisotropic layer 16B is a layer in which disc-shaped liquid crystal compounds LC, which are twisted and oriented along a helical axis extending in the thickness direction, are fixed. When forming the third optical anisotropy layer 16B described above, it is preferable to use at least a disc-shaped liquid crystal compound and a chiral agent.

[0082] The torsion angle of the disc-shaped liquid crystal compound (the torsion angle in the orientation direction of the disc-shaped liquid crystal compound) is not particularly limited and is often greater than 0° and less than or equal to 360°. However, a range of 80±30° (50~110°) is preferred, and a range of 80±20° (60~100°) is more preferred, in terms of achieving superior effects of the present invention. The torsional angle will be measured using Axometrics' AxoScan (polarimeter) device and their device analysis software. Furthermore, the torsional orientation of the disc-shaped liquid crystal compound means that the disc-shaped liquid crystal compound twists around the thickness direction of the third optical anisotropy layer 16B, from one main surface to the other main surface of the third optical anisotropy layer 16B. Consequently, the orientation direction (in-plane slow phase axis direction) of the disc-shaped liquid crystal compound differs depending on its position in the thickness direction of the third optical anisotropy layer 16B. In the torsional orientation, the disc-shaped liquid crystal compound is vertically oriented. The state in which the disc-shaped liquid crystal compound is vertically oriented means that the disc surface of the disc-shaped liquid crystal compound and the thickness direction of the third optical anisotropy layer 16B are parallel. However, strict parallelism is not required; the angle between the disc surface and the thickness direction of the third optical anisotropy layer 16B is preferably in the range of 0 ± 20°, and preferably in the range of 0 ± 10°.

[0083] The angle between the in-plane slow axis of the second optical anisotropy layer 14B and the in-plane slow axis of the third optical anisotropy layer 16B on the surface facing the second optical anisotropy layer 14B is in the range of 0 to 30°, and preferably in the range of 0 to 20°.

[0084] The value of the product Δnd, which is the refractive index anisotropy Δn of the third optical anisotropy layer 16B at a wavelength of 550 nm and the thickness d of the third optical anisotropy layer 16B, is not particularly limited. However, 120 to 240 nm is preferred, and 130 to 230 nm is more preferred, in terms of achieving superior effects of the present invention. The above Δnd measurement method uses Axometrics' AxoScan (polarimeter) device and their device analysis software.

[0085] The type of disc-shaped liquid crystal compound used to form the third optical anisotropy layer 16B is not particularly limited, and known compounds can be used. The disc-shaped liquid crystal compound may have polymerizable groups. The types of polymerizable groups that the disc-shaped liquid crystal compound may have are as described above.

[0086] The third optically anisotropic layer 16B is preferably a layer formed by fixing a disc-shaped liquid crystal compound having polymerizable groups by polymerization. More specifically, it is more preferable that the layer is formed by fixing a disc-shaped liquid crystal compound having twistedly oriented polymerizable groups by polymerization.

[0087] The thickness of the third optical anisotropy layer 16B 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. Note that the thickness of the third optical anisotropy layer 16B refers to the average thickness of the third optical anisotropy layer 16B. The above average thickness is obtained by measuring the thickness of any five or more points on the third optical anisotropy layer 16B and taking their arithmetic mean.

[0088] (Fourth optical anisotropy layer 18B) The fourth optical anisotropy layer 18B is a negative C plate. The retardation in the thickness direction of the fourth optical anisotropy layer 18B at a wavelength of 550 nm is not particularly limited, but 5 to 100 nm is preferred, and 10 to 80 nm is more preferred, in terms of achieving superior effects of the present invention.

[0089] The fourth optical anisotropy layer 18B is not particularly limited in its composition as long as it is a negative C plate. Examples include a layer with horizontally oriented disc-shaped liquid crystal compounds fixed to it, and a resin film. A layer with horizontally oriented disc-shaped liquid crystal compounds fixed to it is preferred because it exhibits superior effects compared to the present invention.

[0090] Known compounds can be used as the disc-shaped liquid crystal compound. Examples of disc-shaped liquid crystal compounds include the disc-shaped liquid crystal compound exemplified in the second optical anisotropy layer 14A. The disc-shaped liquid crystal compound may have polymerizable groups. The types of polymerizable groups that the disc-shaped liquid crystal compound may have are as described above.

[0091] The type of resin that makes up the resin film is not particularly limited, but TAC (triacetylcellulose) is one example.

[0092] The fourth optical anisotropic layer 18B is preferably a layer formed by fixing horizontally oriented, polymerizable, disc-shaped liquid crystal compounds by polymerization.

[0093] The thickness of the fourth optical anisotropy layer 18B is not particularly limited. When the fourth optical anisotropy layer 18B is a layer in which horizontally oriented disc-shaped liquid crystal compounds are fixed, the thickness is preferably 10 μm or less, more preferably 0.1 to 5.0 μm, and even more preferably 0.3 to 2.0 μm. When the fourth optical anisotropy layer 18B is a resin film, the thickness of the fourth optical anisotropy layer 18B is preferably 10 to 100 μm, and more preferably 15 to 90 μm. Note that the thickness of the fourth optical anisotropy layer 18B refers to the average thickness of the fourth optical anisotropy layer 18B. The above average thickness is obtained by measuring the thickness of any five or more points on the fourth optical anisotropy layer 18B and taking their arithmetic mean.

[0094] (Other components) The phase difference film 10B may include other components besides the first optical anisotropy layer 12B to the fourth optical anisotropy layer 18B described above. Other components include those described in the first embodiment of the phase difference film mentioned above.

[0095] The method for manufacturing the first optical anisotropy layer 12B to the fourth optical anisotropy layer 18B is not particularly limited, and the method for manufacturing the first optical anisotropy layer 12A to the fourth optical anisotropy layer 18A described above is an example.

[0096] <Second embodiment of a circular polarizing plate> A second embodiment of the phase difference film of the present invention can be used as a circular polarizer in combination with a polarizer. The circular polarizing plate of the present invention having the above configuration is suitably used for anti-reflective applications in display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescent displays (ELDs), and cathode ray tube displays (CRTs). The polarizer is as described in the first embodiment.

[0097] Figure 6 shows a schematic cross-sectional view of one embodiment of the circular polarizer 100B. Figure 7 shows the relationship between the absorption axis of the polarizer 20 and the in-plane slow axis of the second optical anisotropy layer 14B and the third optical anisotropy layer 16B in the circular polarizer 100B shown in Figure 6. In Figure 7, the arrow in the polarizer 20 represents the absorption axis, and the arrows in the second optical anisotropy layer 14B and the third optical anisotropy layer 16B represent the in-plane slow axis in their respective layers. Figure 8 shows the relationship between the angle between the absorption axis of the polarizer 20 (dashed line) and the in-plane slow phase axes (solid lines) of the second optical anisotropy layer 14B and the third optical anisotropy layer 16B, respectively, as observed from the white arrow in Figure 6. The rotation angle of the in-plane slow axis is expressed as a positive angle for counterclockwise rotation and a negative angle for clockwise rotation, based on the absorption axis of the polarizer 20 (0°) when observed from the white arrow in Figure 6. The twist direction is determined as either right-handed (clockwise) or left-handed (counterclockwise) twist, based on the in-plane slow axis on the front surface (opposite side of the polarizer 20) of the third optical anisotropy layer 16B when observed from the white arrow in Figure 6.

[0098] As shown in Figure 6, the circular polarizer 100B includes a polarizer 20, a first optical anisotropy layer 12B, a second optical anisotropy layer 14B, a third optical anisotropy layer 16B, and a fourth optical anisotropy layer 18B in that order. As shown in Figures 7-8, the angle φb1 between the absorption axis of the polarizer 20 and the in-plane slow axis of the second optical anisotropy layer 14B is 15°. More specifically, the in-plane slow axis of the second optical anisotropy layer 14B is rotated 15° (15° counterclockwise) with respect to the absorption axis of the polarizer 20. Although Figures 7-8 show an embodiment where the in-plane slow axis of the second optical anisotropy layer 14B is at a position of 15°, the present invention is not limited to this embodiment, and it is preferable that it be within the range of 15±13°. In other words, it is preferable that the angle between the absorption axis of the polarizer 20 and the in-plane slow axis of the second optical anisotropy layer 14B be within the range of 15±13°. As shown in Figure 7, within the second optical anisotropy layer 14B, the in-plane slow axis at the polarizer 20 side surface 141B of the second optical anisotropy layer 14B is parallel to the in-plane slow axis at the third optical anisotropy layer 16B side surface 142B of the second optical anisotropy layer 14B.

[0099] As shown in Figures 7-8, the in-plane slow axis of the second optical anisotropy layer 14B and the in-plane slow axis of the third optical anisotropy layer 16B on the surface 161B facing the second optical anisotropy layer 14B are parallel. In Figures 7-8, the in-plane slow axis of the second optical anisotropy layer 14B and the in-plane slow axis of the third optical anisotropy layer 16B on the second optical anisotropy layer 14B side surface 161B are shown to be parallel. However, the present invention is not limited to this embodiment, and the angle between the in-plane slow axis of the second optical anisotropy layer 14B and the in-plane slow axis of the third optical anisotropy layer 16B on the second optical anisotropy layer 14B side surface 161B may be within the range of 0 to 30°. Therefore, for example, when observed from the white arrow in Figure 6, the in-plane slow axis of the third optical anisotropy layer 16B on the second optical anisotropy layer 14B side surface 161B may be positioned 30° clockwise or 30° counterclockwise, relative to the in-plane slow axis of the second optical anisotropy layer 14B. As described above, the third optical anisotropy layer 16B is a layer in which a disc-shaped liquid crystal compound, twisted and oriented along a helical axis extending in the thickness direction, is fixed. Therefore, as shown in Figures 7-8, the in-plane slow axis on the surface 161B of the third optical anisotropy layer 16B on the polarizer 20 side and the in-plane slow axis on the surface 162B of the third optical anisotropy layer 16B opposite to the polarizer 20 side form the aforementioned twist angle (80° in Figure 7). In other words, the angle φb2 between the in-plane slow axis on the surface 161B of the third optical anisotropy layer 16B on the second optical anisotropy layer 14B side and the in-plane slow axis on the surface 162B of the third optical anisotropy layer 16B opposite to the second optical anisotropy layer 14B side is 80°. More specifically, the torsion direction of the disc-shaped liquid crystal compound in the third optical anisotropy layer 16B is right-handed (clockwise), and the torsion angle is 80°. Therefore, the angle between the absorption axis of the polarizer 20 and the in-plane slow phase axis on the surface 162B of the third optical anisotropy layer 16B opposite to the second optical anisotropy layer 14B is 95°. In Figures 7-8, the torsion angle of the disc-shaped liquid crystal compound in the third optical anisotropy layer 16B is shown to be 80°. However, the model is not limited to this model, and the torsion angle of the disc-shaped liquid crystal compound is preferably within the range of 80±30°. In other words, the angle between the in-plane slow axis on the surface 161B of the third optical anisotropy layer 16B on the side of the second optical anisotropy layer 14B and the in-plane slow axis on the surface 162B of the third optical anisotropy layer 16B opposite to the side of the second optical anisotropy layer 14B is preferably within the range of 80±30°.

[0100] As described above, in the embodiments shown in Figures 7-8, when the circular polarizer 100B is observed from the phase difference film 10B side, the in-plane slow axis of the second optical anisotropy layer 14B is rotated 15° counterclockwise with respect to the absorption axis of the polarizer 20, and the twist direction of the disc-shaped liquid crystal compound in the third optical anisotropy layer 16B is clockwise (right-handed twist). Figures 7-8 detail the configuration in which the torsion direction of the disc-shaped liquid crystal compound is clockwise, but a counterclockwise configuration is also possible as long as the predetermined angular relationship is satisfied. More specifically, when the circular polarizer 100B is observed from the phase difference film 10B side, the in-plane slow phase axis of the second optical anisotropy layer 14B is rotated 15° clockwise with respect to the absorption axis of the polarizer 20, and the torsion direction of the disc-shaped liquid crystal compound in the third optical anisotropy layer 16B is counterclockwise (left-handed twist).

[0101] In other words, in a circular polarizer including the second embodiment of the phase difference film, when the circular polarizer is observed from the phase difference film side, if the in-plane slow axis of the second optical anisotropy layer rotates counterclockwise within a range of 15±13° (preferably 15±10°) with respect to the absorption axis of the polarizer, it is preferable that the twisting direction of the liquid crystal compound in the third optical anisotropy layer is clockwise with respect to the in-plane slow axis on the surface of the third optical anisotropy layer on the fourth optical anisotropy layer side. Furthermore, in a circular polarizer including the second embodiment of the phase difference film, when the circular polarizer is observed from the phase difference film side, if the in-plane slow axis of the second optical anisotropy layer rotates clockwise within a range of 15±13° (preferably 15±10°) with respect to the absorption axis of the polarizer, it is preferable that the twisting direction of the liquid crystal compound in the third optical anisotropy layer is counterclockwise with respect to the in-plane slow axis on the surface of the third optical anisotropy layer on the fourth optical anisotropy layer side.

[0102] The above circular polarizer may have other components besides the phase difference film and polarizer. A circular polarizer may have an adhesion layer between the phase difference film and the polarizer. Examples of adhesion layers include the known adhesive layers and bonding layers mentioned above.

[0103] The method for manufacturing the circular polarizer described above is not particularly limited and includes known methods. For example, one method involves bonding a polarizer and a phase difference film via an adhesion layer.

[0104] <Third embodiment of phase difference film> A third embodiment of the phase difference film of the present invention will be described below with reference to the drawings. Figure 9 shows a schematic cross-sectional view of the third embodiment of the phase difference film of the present invention. The phase difference film 10C has a first optical anisotropy layer 12C, a second optical anisotropy layer 14C, a third optical anisotropy layer 16C, and a fourth optical anisotropy layer 18C in this order, with the second optical anisotropy layer 14C and the third optical anisotropy layer 16C being laminated via an adhesion layer 22. In Figure 9, the first optical anisotropy layer 12C and the second optical anisotropy layer 14C are in direct contact, the second optical anisotropy layer 14C and the third optical anisotropy layer 16C are laminated via an adhesion layer 22, and the third optical anisotropy layer 16C and the fourth optical anisotropy layer 18C are in direct contact. In Figure 9, the first optical anisotropy layer 12C and the second optical anisotropy layer 14C are in direct contact, but an adhesion layer may be placed between them, and the first optical anisotropy layer 12C and the second optical anisotropy layer 14C may be laminated with the adhesion layer in between. Furthermore, although the third optical anisotropy layer 16C and the fourth optical anisotropy layer 18C are in direct contact in Figure 9, an adhesion layer may be placed between them, and the third optical anisotropy layer 16C and the fourth optical anisotropy layer 18C may be laminated with the adhesion layer in between. Furthermore, in Figure 9, the second optical anisotropy layer 14C and the third optical anisotropy layer 16C are laminated with an adhesion layer 22 in between, but the second optical anisotropy layer 14C and the third optical anisotropy layer 16C may be in direct contact with each other.

[0105] A third embodiment of the phase difference film of the present invention satisfies at least one of the following requirements 1 to 4. In particular, it is preferable to satisfy all of requirements 1 to 4 in that the effects of the present invention are superior. Requirement 1: The difference between the average refractive index of the first optical anisotropy layer and the average refractive index of the layer in contact with the surface of the first optical anisotropy layer on the second optical anisotropy layer side is 0.10 or less. Requirement 2: At least one of the following is 0.10 or less: the difference between the average refractive index of the second optical anisotropy layer and the average refractive index of the layer in contact with the surface of the second optical anisotropy layer on the first optical anisotropy layer side, and the difference between the average refractive index of the second optical anisotropy layer and the average refractive index of the layer in contact with the surface of the second optical anisotropy layer on the third optical anisotropy layer side. Requirement 3: At least one of the following is 0.10 or less: the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the layer in contact with the surface of the third optical anisotropy layer on the second optical anisotropy layer side, and the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the layer in contact with the surface of the third optical anisotropy layer on the fourth optical anisotropy layer side. Requirement 4: The difference between the average refractive index of the fourth optical anisotropy layer and the average refractive index of the layer in contact with the surface of the fourth optical anisotropy layer on the third optical anisotropy layer side is 0.10 or less. The requirements 1 to 4 will be explained below using the phase difference film shown in Figure 9 as an example.

[0106] Requirement 1 stipulates that the difference between the average refractive index of the first optical anisotropy layer and the average refractive index of the layer in contact with the surface of the first optical anisotropy layer on the second optical anisotropy layer side is 0.10 or less. In Figure 9, the layer in contact with the surface of the first optical anisotropy layer 12C on the second optical anisotropy layer 14C side is the second optical anisotropy layer 14C itself. Therefore, in Figure 9, if the difference between the average refractive index of the first optical anisotropy layer 12C and the average refractive index of the second optical anisotropy layer 14C is 0.10 or less, Requirement 1 is satisfied. The difference mentioned above is the difference between the larger of the two average refractive indices. If the two values ​​are the same, the difference is 0. In Figure 9, the first optical anisotropy layer and the second optical anisotropy layer were in direct contact. However, if the first optical anisotropy layer and the second optical anisotropy layer are laminated with an adhesion layer in between, and the first optical anisotropy layer and the adhesion layer are in contact, then requirement 1 is satisfied if the difference between the average refractive index of the first optical anisotropy layer and the average refractive index of the adhesion layer is 0.10 or less.

[0107] Requirement 2 stipulates that at least one of the following differences must be 0.10 or less: the difference between the average refractive index of the second optical anisotropy layer and the average refractive index of the layer in contact with the surface of the second optical anisotropy layer on the first optical anisotropy layer side, and the difference between the average refractive index of the second optical anisotropy layer and the average refractive index of the layer in contact with the surface of the second optical anisotropy layer on the third optical anisotropy layer side. In Figure 9, the layer in contact with the surface of the second optical anisotropy layer 14C on the first optical anisotropy layer 12C side is the first optical anisotropy layer 12C itself. The layer in contact with the surface of the second optical anisotropy layer 14C on the third optical anisotropy layer 16C side is the adhesion layer 22. Therefore, in Figure 9, if at least one of the differences between the average refractive index of the second optical anisotropy layer 14C and the average refractive index of the first optical anisotropy layer 12C, and the difference between the average refractive index of the second optical anisotropy layer 14C and the average refractive index of the adhesion layer 22 is 0.10 or less, then requirement 2 is satisfied. The difference mentioned above is the difference between the larger of the two average refractive indices. If the two values ​​are the same, the difference is 0. In Figure 9, the second optical anisotropy layer and the third optical anisotropy layer were laminated with an adhesion layer in between. However, if the second optical anisotropy layer and the third optical anisotropy layer are in direct contact, requirement 2 is satisfied if at least one of the differences between the average refractive index of the second optical anisotropy layer and the average refractive index of the first optical anisotropy layer, and the difference between the average refractive index of the second optical anisotropy layer and the average refractive index of the third optical anisotropy layer, is 0.10 or less. Furthermore, although Figure 9 shows a configuration in which the first optical anisotropy layer and the second optical anisotropy layer are in direct contact, if the first optical anisotropy layer and the second optical anisotropy layer are laminated with an adhesion layer in between, and the second optical anisotropy layer and the adhesion layer are in contact, then requirement 2 is satisfied if at least one of the following is 0.10 or less: the difference between the average refractive index of the second optical anisotropy layer and the average refractive index of the adhesion layer in contact with the surface of the second optical anisotropy layer on the first optical anisotropy layer side, and the difference between the average refractive index of the second optical anisotropy layer and the average refractive index of the adhesion layer in contact with the surface of the second optical anisotropy layer on the third optical anisotropy layer side. Furthermore, if the first optical anisotropy layer and the second optical anisotropy layer are laminated with an adhesion layer in between, the second optical anisotropy layer and the adhesion layer are in contact, and the second optical anisotropy layer and the third optical anisotropy layer are in direct contact, then requirement 2 is satisfied if at least one of the difference between the average refractive index of the second optical anisotropy layer and the average refractive index of the adhesion layer, and the difference between the average refractive index of the second optical anisotropy layer and the average refractive index of the third optical anisotropy layer is 0.10 or less.

[0108] Requirement 3 stipulates that at least one of the following differences must be 0.10 or less: the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the layer in contact with the surface of the third optical anisotropy layer on the second optical anisotropy layer side, and the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the layer in contact with the surface of the third optical anisotropy layer on the fourth optical anisotropy layer side. In Figure 9, the layer in contact with the surface of the third optical anisotropy layer 16C on the second optical anisotropy layer 14C side is the adhesion layer 22. Also, the layer in contact with the surface of the third optical anisotropy layer 16C on the fourth optical anisotropy layer 18C side is the fourth optical anisotropy layer 18C itself. Therefore, in Figure 9, if at least one of the differences between the average refractive index of the third optical anisotropy layer 16C and the average refractive index of the adhesion layer 22, and the difference between the average refractive index of the third optical anisotropy layer 16C and the average refractive index of the fourth optical anisotropy layer 18C is 0.10 or less, then requirement 3 is satisfied. The difference mentioned above is the difference between the larger of the two average refractive indices. If the two values ​​are the same, the difference is 0. In Figure 9, the second optical anisotropy layer and the third optical anisotropy layer were laminated with an adhesion layer in between. However, if the second optical anisotropy layer and the third optical anisotropy layer are in direct contact, requirement 3 will be satisfied if at least one of the differences between the average refractive index of the third optical anisotropy layer and the average refractive index of the second optical anisotropy layer, and the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the fourth optical anisotropy layer, is 0.10 or less. Furthermore, although Figure 9 shows a configuration in which the third optical anisotropy layer and the fourth optical anisotropy layer are in direct contact, if the third optical anisotropy layer and the fourth optical anisotropy layer are laminated with an adhesion layer in between, and the third optical anisotropy layer and the adhesion layer are in contact, then requirement 3 is satisfied if at least one of the following is 0.10 or less: the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the adhesion layer in contact with the surface of the third optical anisotropy layer on the second optical anisotropy layer side, and the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the adhesion layer in contact with the surface of the third optical anisotropy layer on the fourth optical anisotropy layer side. Furthermore, if the third optical anisotropy layer and the fourth optical anisotropy layer are laminated with an adhesion layer in between, and the third optical anisotropy layer and the adhesion layer are in contact, and the third optical anisotropy layer and the second optical anisotropy layer are in direct contact, then requirement 3 will be satisfied if at least one of the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the adhesion layer, and the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the second optical anisotropy layer is 0.10 or less.

[0109] Requirement 4 stipulates that the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the layer in contact with the surface of the fourth optical anisotropy layer on the third optical anisotropy layer side must be 0.10 or less. In Figure 9, the layer in contact with the surface of the fourth optical anisotropy layer 18C on the third optical anisotropy layer 16C side is the third optical anisotropy layer 16C itself. Therefore, in Figure 9, if the difference between the average refractive index of the fourth optical anisotropy layer 18C and the average refractive index of the third optical anisotropy layer 16C is 0.10 or less, requirement 4 will be satisfied. The difference mentioned above is the difference between the larger of the two average refractive indices. If the two values ​​are the same, the difference is 0. In Figure 9, the fourth optical anisotropy layer and the third optical anisotropy layer were in direct contact. However, if the fourth optical anisotropy layer and the third optical anisotropy layer are laminated with an adhesion layer in between, and the fourth optical anisotropy layer and the adhesion layer are in contact, then requirement 4 will be satisfied if the difference between the average refractive index of the fourth optical anisotropy layer and the average refractive index of the adhesion layer is 0.10 or less.

[0110] (Optical anisotropy layer) In the third embodiment of the phase difference film, the first optical anisotropy layer 12C to the fourth optical anisotropy layer 18C are all different layers. Examples of layers being different include different types of liquid crystal compounds used to form the optical anisotropy layers, different orientation forms or orientation directions of the liquid crystal compounds in the optical anisotropy layers, and different optical properties of the optical anisotropy layers (e.g., in-plane retardation and retardation in the thickness direction).

[0111] The first optical anisotropy layer 12C to the fourth optical anisotropy layer 18C are preferably layers formed by fixing oriented liquid crystal compounds, and more preferably layers formed by fixing a liquid crystal compound having polymerizable groups by polymerization. The types of liquid crystal compounds are not particularly limited, and generally, liquid crystal compounds can be classified into rod-shaped liquid crystal compounds and disc-shaped liquid crystal compounds based on their shape. Liquid crystal compounds preferably have polymerizable groups. In other words, liquid crystal compounds are preferably polymerizable liquid crystal compounds. Examples of polymerizable groups in polymerizable liquid crystal compounds include acryloyl groups, methacryloyl groups, epoxy groups, and vinyl groups.

[0112] Possible orientation states for liquid crystal compounds include, for example, homogeneous orientation, homeotropic orientation, hybrid orientation, torsional orientation, and skewed orientation. The torsional orientation, in particular, refers to an orientation state in which the liquid crystal compound is twisted from one main surface to the other of the optically anisotropic layer, with the thickness direction of the optically anisotropic layer as the axis of rotation. In torsional orientation, the twist angle of the liquid crystal compound (the twist angle in the orientation direction of the liquid crystal compound) is usually greater than 0° and less than or equal to 360°.

[0113] At least one of the first optical anisotropy layer 12C to the fourth optical anisotropy layer 18C may be the A plate described above, a negative A plate, or a positive A plate.

[0114] Furthermore, at least one of the first optical anisotropy layer 12C to the fourth optical anisotropy layer 18C may be a C plate as described above, a negative C plate, or a positive C plate.

[0115] Furthermore, at least one of the first optical anisotropy layer 12C to the fourth optical anisotropy layer 18C may be a layer in which a torsion-oriented liquid crystal compound is fixed (a layer in which a torsion-oriented liquid crystal compound is fixed along a helical axis extending in the thickness direction). The liquid crystal compound used in the layer formed by fixing a twisted-oriented liquid crystal compound is preferably a rod-shaped liquid crystal compound.

[0116] The thickness of the first optical anisotropy layer 12C to the fourth optical anisotropy layer 18C 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 3.0 μm. Note that the thickness of each layer from the first optical anisotropy layer 12C to the fourth optical anisotropy layer 18C refers to the average thickness of each layer. The above average thickness is obtained by measuring the thickness of any five or more points in each layer and taking the arithmetic mean of these measurements.

[0117] One preferred embodiment of the first optical anisotropy layer 12C to the fourth optical anisotropy layer 18C is one in which the first optical anisotropy layer 12C is a negative C plate, the second optical anisotropy layer 14C is a negative A plate, the third optical anisotropy layer 16C is a layer in which a rod-shaped liquid crystal compound that is twisted and oriented along a helical axis extending in the thickness direction is fixed, the fourth optical anisotropy layer 18C is a positive C plate, and the angle between the in-plane slow axis of the second optical anisotropy layer 14C and the in-plane slow axis of the third optical anisotropy layer 16C on the surface facing the second optical anisotropy layer 14C is in the range of 0 to 30°. This embodiment (hereinafter also simply referred to as "preferred embodiment 1") corresponds to the embodiment described in the first embodiment of the phase difference film described above, and the preferred embodiments of each layer are the same as the preferred embodiments of each layer described in the first embodiment. Another preferred embodiment of the first optical anisotropy layer 12C to the fourth optical anisotropy layer 18C is one in which the first optical anisotropy layer 12C is a positive C plate, the second optical anisotropy layer 14C is a positive A plate, the third optical anisotropy layer 16C is a layer in which a disc-shaped liquid crystal compound that is twisted and oriented along a helical axis extending in the thickness direction is fixed, the fourth optical anisotropy layer 18C is a negative C plate, and the angle between the in-plane slow axis of the second optical anisotropy layer 14C and the in-plane slow axis of the third optical anisotropy layer 16C on the surface facing the second optical anisotropy layer 14C is in the range of 0 to 30°. This embodiment (hereinafter also simply referred to as "preferred embodiment 2") corresponds to the embodiment described in the second embodiment of the phase difference film described above, and the preferred embodiments of each layer are the same as the preferred embodiments of each layer described in the second embodiment.

[0118] (Intense layer) Examples of the adhesion layer include the adhesion layer (adhesive layer and bonding layer) described in the first embodiment of the phase difference film described above. More specifically, the adhesive layer is a layer formed using an adhesive. Examples of adhesives include water-based adhesives, solvent-based adhesives, emulsion-based adhesives, solvent-free adhesives, active energy ray-curing adhesives, and thermosetting adhesives. Examples of active energy ray-curing adhesives include electron beam-curing adhesives, ultraviolet-curing adhesives, and visible light-curing adhesives, with ultraviolet-curing adhesives being preferred. In other words, the adhesion layer is preferably a layer formed using an ultraviolet-curing adhesive. Specific examples of active energy ray curing adhesives include (meth)acrylate adhesives. Examples of curing components in (meth)acrylate adhesives include compounds having a (meth)acryloyl group and compounds having a vinyl group.

[0119] The thickness of the adhesive layer is not particularly limited, but is preferably 0.1 to 5 μm, and more preferably 0.5 to 2 μm.

[0120] The adhesive layer is a layer formed using an adhesive. Examples of adhesives include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives, with acrylic-based adhesives (pressure-sensitive adhesives) being preferred. As an acrylic adhesive, a copolymer of (meth)acrylate, in which the alkyl group of the ester portion is an alkyl group having 20 or fewer carbon atoms such as a methyl group, an ethyl group, or a butyl group, and a (meth)acrylic monomer having a functional group such as (meth)acrylic acid or hydroxyethyl (meth)acrylate is preferred.

[0121] The thickness of the adhesive layer is not particularly limited, but is preferably 1 to 30 μm, and more preferably 5 to 20 μm.

[0122] The method for manufacturing the first optical anisotropy layer 12C to the fourth optical anisotropy layer 18C is not particularly limited, and the method for manufacturing the first optical anisotropy layer 12A to the fourth optical anisotropy layer 18A described above is an example. More specifically, in order to form a state in which two optically anisotropic layers are in direct contact, for example, an optically anisotropic layer can be formed by applying an optically anisotropic layer-forming composition containing a liquid crystal compound having polymerizable groups (preferably containing a material that imparts orientation control ability to the surface of the optically anisotropic layer (e.g., a photo-alignment polymer) in the optically anisotropic layer-forming composition) to a substrate, and then applying another optically anisotropic layer-forming composition containing a liquid crystal compound having polymerizable groups on the formed optically anisotropic layer to form a separate optically anisotropic layer, thereby creating a state in which the two optically anisotropic layers are in direct contact. Furthermore, in order to form a state in which two optically anisotropic layers are arranged via an adhesion layer, for example, this state can be formed by bonding two separately prepared optically anisotropic layers via an adhesion layer. As described above, the phase difference film of the present invention can be formed by combining a coating method using an optical anisotropic layer-forming composition containing a polymerizable liquid crystal compound and a lamination method.

[0123] The third embodiment of the phase difference film described above can be used as a circular polarizer in combination with a polarizer, similar to the first and second embodiments of the phase difference film described above. If the third embodiment of the phase difference film is the preferred embodiment 1 described above, it is preferable to combine the third embodiment of the phase difference film with the polarizer so that the layer arrangement is the same as that of the first embodiment of the circular polarizer described above. Furthermore, if the third embodiment of the phase difference film is the preferred embodiment 2 described above, it is preferable to combine the third embodiment of the phase difference film with the polarizer so that the layer arrangement is the same as that of the second embodiment of the circular polarizer described above.

[0124] When combining the third embodiment of the phase difference film with a polarizer, the two may be laminated together via the aforementioned adhesion layer. When laminating the third embodiment of the phase difference film with a polarizer via an adhesion layer, it is preferable that the difference between the average refractive index of the optical anisotropy layer in the phase difference film adjacent to the adhesion layer and the average refractive index of the adhesion layer be 0.10 or less.

[0125] <Fourth embodiment of phase difference film> A fourth embodiment of the phase difference film of the present invention will be described below with reference to the drawings. Figure 10 shows a schematic cross-sectional view of the fourth embodiment of the phase difference film of the present invention. The phase difference film 10D has a first optical anisotropy layer 12D, a second optical anisotropy layer 14D, a third optical anisotropy layer 16D, and a fourth optical anisotropy layer 18D in this order, with the second optical anisotropy layer 14D and the third optical anisotropy layer 16D being laminated via an adhesion layer 22. The adhesion layer 22 is in contact with the second optical anisotropy layer 14D and the third optical anisotropy layer 16D. In Figure 10, the second optical anisotropy layer 14D and the third optical anisotropy layer 16D are laminated via an adhesion layer 22, but the embodiment is not limited to this, and it is sufficient that at least one of the following is laminated via an adhesion layer: the first optical anisotropy layer and the second optical anisotropy layer, the second optical anisotropy layer and the third optical anisotropy layer, and the third optical anisotropy layer and the fourth optical anisotropy layer.

[0126] In the fourth embodiment of the phase difference film of the present invention, the following requirement 5 is satisfied. Requirement 5: The difference between the average refractive index of the adhesion layer and the average refractive index of the optical anisotropy layer adjacent to the adhesion layer is 0.10 or less. The above points will be explained below using the phase difference film shown in Figure 10 as an example. In Figure 10, the second optical anisotropy layer 14D and the third optical anisotropy layer 16D are laminated with an adhesion layer 22 in between. In this embodiment, the adhesion layer and the second optical anisotropy layer 14D and the third optical anisotropy layer 16D are adjacent to each other. Therefore, the difference between the average refractive index of the adhesion layer and the average refractive index of the second optical anisotropy layer 14D is 0.10 or less, and the difference between the average refractive index of the adhesion layer and the average refractive index of the third optical anisotropy layer 16D is 0.10 or less. Furthermore, if the first optical anisotropy layer 12D and the second optical anisotropy layer 14D are laminated with an adhesion layer 22 in between, and the two optical anisotropy layers (first optical anisotropy layer 12D, second optical anisotropy layer 14D) are in contact with the adhesion layer 22, then requirement 5 above is satisfied if the difference between the average refractive index of the adhesion layer and the average refractive index of the first optical anisotropy layer 12D is 0.10 or less, and the difference between the average refractive index of the adhesion layer and the average refractive index of the second optical anisotropy layer 14D is 0.10 or less. Furthermore, if the third optical anisotropy layer 16D and the fourth optical anisotropy layer 18D are laminated via an adhesion layer 22, and the two optical anisotropy layers (third optical anisotropy layer 16D and fourth optical anisotropy layer 18D) are in contact with the adhesion layer 22, then requirement 5 above is satisfied if the difference between the average refractive index of the adhesion layer and the average refractive index of the third optical anisotropy layer 16D is 0.10 or less, and the difference between the average refractive index of the adhesion layer and the average refractive index of the fourth optical anisotropy layer 18D is 0.10 or less.

[0127] In particular, one preferred embodiment of the fourth embodiment of the phase difference film is one in which a second optical anisotropy layer and a third optical anisotropy layer are laminated with an adhesion layer in between, and the difference between the average refractive index of the adhesion layer and the average refractive index of the second optical anisotropy layer is 0.08 or less, and the difference between the average refractive index of the adhesion layer and the average refractive index of the third optical anisotropy layer is 0.08 or less.

[0128] Furthermore, another preferred embodiment of the fourth embodiment of the phase difference film is an embodiment that satisfies all of requirements 1 to 4 described in the third embodiment of the phase difference film.

[0129] (Optical anisotropy layer) In the fourth embodiment of the phase difference film, the first optical anisotropy layer 12D to the fourth optical anisotropy layer 18D are all different layers. Examples of these differences include the different types of liquid crystal compounds used to form the optical anisotropy layers, the different orientation forms or orientation directions of the liquid crystal compounds in the optical anisotropy layers, and the different optical properties of the optical anisotropy layers (e.g., in-plane retardation and thickness-direction retardation).

[0130] The first optical anisotropy layer 12D to the fourth optical anisotropy layer 18D are preferably layers formed by fixing oriented liquid crystal compounds, and more preferably layers formed by fixing a liquid crystal compound having polymerizable groups by polymerization. The types of liquid crystal compounds are not particularly limited, and generally, liquid crystal compounds can be classified into rod-shaped liquid crystal compounds and disc-shaped liquid crystal compounds based on their shape. Liquid crystal compounds preferably have polymerizable groups. In other words, liquid crystal compounds are preferably polymerizable liquid crystal compounds. Examples of polymerizable groups in polymerizable liquid crystal compounds include acryloyl groups, methacryloyl groups, epoxy groups, and vinyl groups.

[0131] Possible orientation states for liquid crystal compounds include, for example, homogeneous orientation, homeotropic orientation, hybrid orientation, torsional orientation, and skewed orientation. The torsional orientation, in particular, refers to an orientation state in which the liquid crystal compound is twisted from one main surface to the other of the optically anisotropic layer, with the thickness direction of the optically anisotropic layer as the axis of rotation. In torsional orientation, the twist angle of the liquid crystal compound (the twist angle in the orientation direction of the liquid crystal compound) is usually greater than 0° and less than or equal to 360°.

[0132] At least one of the first optical anisotropy layer 12D to the fourth optical anisotropy layer 18D may be an A plate as described above, a negative A plate, or a positive A plate.

[0133] Furthermore, at least one of the first optical anisotropy layer 12D to the fourth optical anisotropy layer 18D may be a C plate as described above, a negative C plate, or a positive C plate.

[0134] Furthermore, at least one of the first optical anisotropy layer 12D to the fourth optical anisotropy layer 18D may be a layer in which a torsion-oriented liquid crystal compound is fixed (a layer in which a torsion-oriented liquid crystal compound is fixed along a helical axis extending in the thickness direction). The liquid crystal compound used in the layer formed by fixing a twisted-oriented liquid crystal compound is preferably a rod-shaped liquid crystal compound.

[0135] The thickness of the first optical anisotropy layer 12D to the fourth optical anisotropy layer 18D 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 3.0 μm. Note that the thickness of each layer from the first optical anisotropy layer 12D to the fourth optical anisotropy layer 18D refers to the average thickness of each layer. The above average thickness is obtained by measuring the thickness of any five or more points in each layer and taking the arithmetic mean of these measurements.

[0136] One preferred embodiment of the first optical anisotropy layer 12D to the fourth optical anisotropy layer 18D is a configuration in which the first optical anisotropy layer 12D is a negative C plate, the second optical anisotropy layer 14D is a negative A plate, the third optical anisotropy layer 16D is a layer in which a rod-shaped liquid crystal compound, twisted and oriented along a helical axis extending in the thickness direction, is fixed, the fourth optical anisotropy layer 18D is a positive C plate, and the angle between the in-plane slow axis of the second optical anisotropy layer 14D and the in-plane slow axis of the third optical anisotropy layer 16D on the surface facing the second optical anisotropy layer 14D is in the range of 0 to 30°. This embodiment (hereinafter also simply referred to as "preferred embodiment 3") corresponds to the embodiment described in the first embodiment of the phase difference film described above, and the preferred embodiments of each layer are the same as the preferred embodiments of each layer described in the first embodiment. Another preferred embodiment of the first optical anisotropy layer 12D to the fourth optical anisotropy layer 18D is one in which the first optical anisotropy layer 12D is a positive C plate, the second optical anisotropy layer 14D is a positive A plate, the third optical anisotropy layer 16D is a layer in which a disc-shaped liquid crystal compound that is twisted and oriented along a helical axis extending in the thickness direction is fixed, the fourth optical anisotropy layer 18D is a negative C plate, and the angle between the in-plane slow axis of the second optical anisotropy layer 14D and the in-plane slow axis of the third optical anisotropy layer 16D on the surface facing the second optical anisotropy layer 14D is in the range of 0 to 30°. This embodiment (hereinafter also simply referred to as "preferred embodiment 4") corresponds to the embodiment described in the second embodiment of the phase difference film described above, and the preferred embodiments of each layer are the same as the preferred embodiments of each layer described in the second embodiment.

[0137] (Intense layer) Examples of the adhesion layer include the adhesion layer (adhesive layer and bonding layer) described in the third embodiment of the phase difference film described above.

[0138] The method for manufacturing the first optical anisotropy layer 12D to the fourth optical anisotropy layer 18D is not particularly limited, and the method for manufacturing the first optical anisotropy layer 12C to the fourth optical anisotropy layer 18C described above is an example.

[0139] The fourth embodiment of the phase difference film described above can be used as a circular polarizer in combination with a polarizer, similar to the first and second embodiments of the phase difference film described above. If the fourth embodiment of the phase difference film is the preferred embodiment 3 described above, it is preferable to combine the fourth embodiment of the phase difference film with the polarizer so that the layer arrangement is the same as that of the first embodiment of the circular polarizer described above. Furthermore, if the fourth embodiment of the phase difference film is the preferred embodiment 4 described above, it is preferable to combine the fourth embodiment of the phase difference film with the polarizer so that the layer arrangement is the same as that of the second embodiment of the circular polarizer described above.

[0140] When combining the fourth embodiment of the phase difference film with a polarizer, the two may be laminated together via the aforementioned adhesion layer. When laminating the fourth embodiment of the phase difference film with a polarizer via an adhesion layer, it is preferable that the difference between the average refractive index of the optical anisotropy layer in the phase difference film adjacent to the adhesion layer and the average refractive index of the adhesion layer be 0.10 or less.

[0141] <Application> The phase difference film described above can be applied to various uses. For example, by adjusting the optical properties of each optical anisotropy layer, it can be used as a so-called λ / 4 plate or λ / 2 plate. A λ / 4 plate is a plate that has the function of converting linearly polarized light of a specific wavelength into circularly polarized light (or circularly polarized light into linearly polarized light). More specifically, it is a plate in which the in-plane retardation Re at a given wavelength λnm is λ / 4 (or an odd multiple thereof). The in-plane retardation (Re(550)) of the λ / 4 plate at a wavelength of 550 nm is centered around the ideal value (137.5 nm), with an error of about 25 nm acceptable. For example, it is preferably between 110 and 160 nm, and more preferably between 120 and 150 nm. Furthermore, a λ / 2 plate refers to an optically anisotropic film in which the in-plane retardation Re(λ) at a specific wavelength λnm satisfies Re(λ) ≈ λ / 2. This equation only needs to be achieved at any wavelength in the visible light region (for example, 550 nm). In particular, it is preferable that the in-plane retardation Re(550) at a wavelength of 550 nm satisfies the following relationship. 210nm ≤ Re(550) ≤ 300nm

[0142] <Display device> The phase difference films (first to fourth embodiments) and circular polarizers (first and second embodiments) of the present invention can be suitably applied to display devices. The display device of the present invention comprises a display element and the above-mentioned phase difference film or circular polarizing plate. The display device of the present invention preferably includes a display element and, in addition to the above-mentioned phase difference film or circular polarizing plate, a surface protective film further comprising a hard coat layer. When applying the phase difference film of the present invention to a display device, it is preferable to apply it as a circular polarizer as described above. In this case, the circular polarizer is positioned on the viewing side, and within the circular polarizer, the polarizer is positioned on the viewing side. If the display device further has a surface protective film, the surface protective film is positioned even further on the viewing side than the polarizer. That is, the order from the viewing side is surface protective film, polarizer, phase difference film, and display element. The display element is not particularly limited and examples include organic electroluminescent display elements and liquid crystal display elements.

[0143] <Other configurations> The adhesion layer, substrate, and hard coat layer of the surface protective film used on the viewing side of the display device of the present invention may contain an ultraviolet absorber from the viewpoint of improving the light resistance of the display element. The ultraviolet absorber is not particularly limited, and various known ones can be used. For example, the ultraviolet absorber described in International Publication WO2021 / 006097 can be used. Preferably, the transmittance of the laminate on the viewing side of the display element is 1% or less at a wavelength of 380 nm, 20-70% at 410 nm, and 90% or more in the range of 450 nm and above. A transmittance of 40-50% at a wavelength of 410 nm is even more preferable. [Examples]

[0144] The features of the present invention will be further described 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.

[0145] <Example 1> (Preparation of cellulose acylate film) The following composition 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 a 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 (by mass ratio).

[0146] ------------------------------------------------------------------ Cellulose acylate dope ------------------------------------------------------------------ Cellulose acylate (acetyl substitution degree 2.86, viscosity-average degree of polymerization 310) 100 parts by mass Sugar ester compound 1 (shown in formula (S4) below): 6.0 parts by mass Sugar ester compound 2 (shown in formula (S5) below): 2.0 parts by mass Silica particle dispersion (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 0.1 part by mass Solvent (methylene chloride / methanol / butanol) ------------------------------------------------------------------

[0147] [ka]

[0148] [ka]

[0149] The dope prepared as described above was cast using a drum film-forming machine. The dope was cast from the die onto a metal support cooled to 0°C, and then the resulting web (film) was peeled off. The drum was made of stainless steel (SUS).

[0150] After the casting process, the resulting web (film) was peeled from the drum and dried for 20 minutes in a tenter device at 30-40°C during film transport, with clips holding both ends of the web in place. Subsequently, the web was further dried by zone heating while being transported on a roll. The resulting web was then knurled and wound up. The obtained cellulose acylate film had a thickness of 40 μm, with an in-plane retardation of 1 nm at a wavelength of 550 nm and a thickness retardation of 26 nm at a wavelength of 550 nm. In this way, an optically anisotropic layer (1a) consisting of a cellulose acylate film corresponding to the first optically anisotropic layer was fabricated.

[0151] The aforementioned cellulose acylate film is passed through a dielectric heating roll at a temperature of 60°C to raise the film surface temperature to 40°C. Then, an alkaline solution with the composition shown below is applied to the band surface of the film using a bar coater at a rate of 14 ml / m². 2 The material was coated and then transported for 10 seconds under a steam-type far-infrared heater manufactured by Noritake Co., Ltd., heated to 110°C. Subsequently, using the same bar coater, 3 ml / m of pure water was applied. 2The film was then coated. Next, it was washed with water using a fountain coater and dewatered with an air knife three times, and then transported to a 70°C drying zone for 10 seconds to dry, thereby producing an alkaline saponified cellulose acylate film.

[0152] -------------------------------------------------- Alkaline solution -------------------------------------------------- Potassium hydroxide 4.7 parts by mass Water 15.8 parts by mass Isopropanol 63.7 parts by mass Surfactants: C 14 H 29 O(CH2CH2O) 20 H 1.0 parts by mass Propylene glycol 14.8 parts by mass --------------------------------------------------

[0153] (Formation of orientation film) An orientation film coating solution 1 with the following composition was continuously applied to the surface of a cellulose acylate film that had undergone alkali saponification treatment using a #14 wire bar. The resulting coating was then dried with hot air at 60°C for 60 seconds, and then with hot air at 100°C for 120 seconds to obtain orientation film 1.

[0154] ------------------------------------------------------------------ Orientation film coating solution 1 ------------------------------------------------------------------ 28 parts by mass of the modified polyvinyl alcohol shown below Citrate ester (AS3, manufactured by Sankyo Chemical Co., Ltd.) 1.2 parts by mass Photopolymerization initiator (Irgacure 2959, manufactured by BASF) 0.84 parts by mass Glutaraldehyde 2.8 parts by mass Water 699 parts by mass Methanol 226 parts by mass ------------------------------------------------------------------

[0155] (Modified polyvinyl alcohol)

[0156] [ka]

[0157] (Formation of optically anisotropic layer (1b)) The orientation film 1 prepared above was subjected to continuous rubbing. At this time, the longitudinal direction of the long film (cellulose acylate 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°. In other words, when observed from the film side, the position of the rubbing roller's axis of rotation is rotated 76° clockwise relative to the longitudinal direction of the film.

[0158] On the alignment film treated with the rubbing process described above, an optical anisotropy layer-forming composition (1b) 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 110°C hot air for 2 minutes to dry the solvent and mature the alignment of the disc-shaped liquid crystal compound. Then, the obtained composition layer was irradiated with UV light (500 mJ / cm²) at 80°C. 2 The orientation of the disc-shaped liquid crystal compound was fixed by performing the following procedure, and an optical anisotropic layer (1b) corresponding to the second optical anisotropic layer was formed. The thickness of the optically anisotropic layer (1b) was 1.1 μm. The retardation at a wavelength of 550 nm was 168 nm. The average tilt angle of the disc surface of the disc-shaped liquid crystal compound with respect to the film surface was 90°, confirming that it was oriented perpendicular to the film surface. Furthermore, the angle of the in-plane slow axis of the optically anisotropic layer (1b) 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 direction of the optically anisotropic layer (1b) was -14° when viewed from the optically anisotropic layer (1b) side.

[0159] -------------------------------------------------- Composition for forming an optically anisotropic layer (1b) -------------------------------------------------- 180 parts by mass of the following disc-shaped liquid crystal compound The following disc-shaped liquid crystal compound 2: 20 parts by mass The following orientation agent for the interface of the orientation film: 0.55 parts by mass 0.1 parts by mass of the following fluorine-containing compound A 0.05 parts by mass of the following fluorine-containing compound B The following fluorine-containing compound C: 0.21 parts by mass Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 10 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by BASF) 3.0 parts by mass Methyl ethyl ketone 200 parts by mass --------------------------------------------------

[0160] Disc-shaped liquid crystal compound 1

[0161] [ka]

[0162] Disc-shaped liquid crystal compound 2

[0163] [ka]

[0164] Orientation film interface orientation agent 1

[0165]

Chem.

[0166] Fluorine-containing compound A (in the following formula, a and b represent the content (mass %) of each repeating unit with respect to all repeating units, a represents 90 mass %, and b represents 10 mass %).)

[0167]

Chem.

[0168] Fluorine-containing compound B (the numerical values in each repeating unit represent the content (mass %) with respect to all repeating units. The content of the left repeating unit was 32.5 mass %, and the content of the right repeating unit was 67.5 mass %).)

[0169]

Chem.

[0170] Fluorine-containing compound C (the numerical values in each repeating unit represent the content (mass %) with respect to all repeating units. The content of the left repeating unit was 25 mass %, the content of the middle repeating unit was 25 mass %, and the content of the right repeating unit was 50 mass %).)

[0171]

Chem.

[0172] By the above procedure, a laminate (1a-1b) in which the optically anisotropic layer (1a) and the optically anisotropic layer (1b) are laminated was produced.

[0173] (Formation of the optically anisotropic layer (1d)) On the prepared cellulose acetate film, a composition (1d) for forming an optically anisotropic layer containing a rod-like liquid crystal compound with the following composition was applied using a Meyer bar coater to form a composition layer. Then, while holding both ends of the film, a cooling plate (9 °C) was installed on the side where the coated film surface of the film was formed so that the distance from the film was 5 mm, and a heater (75 °C) was installed on the side opposite to the surface where the coated film of the film was formed so that the distance from the film was 5 mm, and it was dried for 2 minutes. Next, the obtained film was heated at 60 °C for 1 minute with warm air, and while purging with nitrogen so that the atmosphere had an oxygen concentration of 100 ppm or less, ultraviolet light with an irradiation dose of 100 mJ / cm 2 was irradiated using a 365 nm UV-LED. Then, the obtained coated film was annealed at 120 °C for 1 minute with warm air to form an optically anisotropic layer (1d) corresponding to the fourth optically anisotropic layer.[[ID=…]] To the obtained optically anisotropic layer (1d), UV light (ultra-high pressure mercury lamp; UL750; manufactured by HOYA) passed through a wire grid polarizer was irradiated at room temperature at 7.9 mJ / cm 2 (wavelength: 313 nm) to form a composition layer having an alignment control ability on the surface. Note that the film thickness of the formed optically anisotropic layer (1d) was 0.6 μm. The in-plane retardation Re at a wavelength of 550 nm was 0 nm, and the thickness-direction retardation Rth at a wavelength of 550 nm was -75 nm. The average tilt angle of the long axis direction of the rod-like liquid crystal compound with respect to the film surface was 90°, and it was confirmed that the compound was vertically aligned with respect to the film surface.

[0174] ―――――――――――――――――――――――――――――――― Composition (1d) for forming an optically anisotropic layer ―――――――――――――――――――――――――――――――― 100 parts by mass of the following rod-like liquid crystal compound (A) 4.0 parts by mass of a polymerizable monomer (A-400, manufactured by Shin-Nakamura Chemical Co., Ltd.) 5.0 parts by mass of the following polymerization initiator S-1 (oxime type) 3.0 parts by mass of the following photoacid generator D-1 2.0 parts by mass of the following polymer M-1 2.0 parts by mass of the following vertical alignment agent S01 2.0 parts by mass of the following photo-alignment polymer A-1 0.2 parts by mass of the following surfactant B-1 42.3 parts by mass of methyl ethyl ketone 627.5 parts by mass of methyl isobutyl ketone ――――――――――――――――――――――――――――――――

[0175] Rod-like liquid crystal compound (A) (hereinafter, a mixture of compounds)

[0176]

Chemical formula

[0177] Polymerization initiator S-1

[0178]

Chemical formula

[0179] Photoacid generator D-1

[0180]

Chemical formula

[0181] Polymer M-1

[0182]

Chemical formula

[0183] Vertical alignment agent S01

[0184]

Chemical formula

[0185] Photo-oriented polymer A-1 (The numerical values ​​indicated within each repeating unit represent the content (mass%) of each repeating unit relative to the total number of repeating units. From left to right, the content was 43% by mass, 27% by mass, and 30% by mass. The weight-average molecular weight was 69800.)

[0186] [ka]

[0187] Surfactant B-1 (weight-average molecular weight was 2200).

[0188] [ka]

[0189] (Formation of optically anisotropic layer (1c)) Next, an optically anisotropic layer-forming composition (1c) containing a rod-shaped liquid crystal compound with the following composition was applied onto the optically anisotropic layer (1d) prepared above using a Gieser coating machine, and heated with 80°C hot air for 60 seconds. Subsequently, the resulting composition layer was irradiated with UV light (500 mJ / cm²) at 80°C. 2 The orientation of the liquid crystal compound was fixed by performing the following procedure, and an optical anisotropy layer (1c) corresponding to the third optical anisotropy layer was formed. The optically anisotropic layer (1c) had a thickness of 1.2 μm, a Δnd of 164 nm at a wavelength of 550 nm, and a torsion angle of 81° of the liquid crystal compound. When the film width direction is 0° (longitudinal direction is 90°), when viewed from the optically anisotropic layer (1c) side, the in-plane slow axis direction (orientation axis angle of the liquid crystal compound) was 14° on the air side and 95° on the side in contact with the optically anisotropic layer (1d). The in-plane slow-moving axis direction of the optical anisotropic layer is expressed by observing the substrate from the surface side of the optical anisotropic layer, with the substrate width direction being the reference 0°, and clockwise (rightward) rotation being negative and counterclockwise (leftward) rotation being positive.

[0190] -------------------------------------------------- Composition for forming optically anisotropic layer (1c) -------------------------------------------------- 100 parts by mass of the above rod-shaped liquid crystal compound (A) 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): 0.60 parts by mass 0.08 parts by mass of the above fluorine-containing compound C Methyl ethyl ketone 156 parts by mass --------------------------------------------------

[0191] Left-hand twist chiral agent (L1) (Bu represents a butyl group.)

[0192] [ka]

[0193] Following the procedure described above, a laminate (1c-1d) was fabricated in which an optically anisotropic layer (1d) and an optically anisotropic layer (1c) were directly laminated onto a long cellulose acylate film. The difference in refractive index between the average refractive index of the optically anisotropic layer (1c) and the average refractive index of the optically anisotropic layer (1d) was within 0.05.

[0194] The surface side of the optically anisotropic layer (1b) formed on the optically anisotropic layer (1a) made of the long cellulose acylate film prepared above, and the surface side of the optically anisotropic layer (1c) of the laminate (1c-1d) formed on the long cellulose acylate film prepared above, were bonded together using an ultraviolet-curing adhesive in a continuous machine such that the angle between the in-plane slow axis of the optically anisotropic layer (1b) and the in-plane slow axis of the surface side of the optically anisotropic layer (1c) was 0°. Furthermore, as the UV-curing adhesive, an adhesive was used in which a high-refractive-index monomer was added to an acrylic compound to control the refractive index after curing to 1.58. The difference in refractive index between the adhesive layer and the adjacent optically anisotropic layer, and between the adhesive layer and the adhesive layer, was both within 0.05. Next, the cellulose acylate film on the optically anisotropic layer (1d) side was peeled off, exposing the surface of the optically anisotropic layer (1d) that had been in contact with the cellulose acylate film. In this way, an optical film (1a-1b-1c-1d) was obtained in which an optically anisotropic layer (1b), an optically anisotropic layer (1c), and an optically anisotropic layer (1d) were laminated in this order on an optically anisotropic layer (1a) made of a long cellulose acylate film.

[0195] (Fabrication of linear polarizing plates) The surface of a cellulose triacetate film TJ25 (manufactured by Fujifilm Corporation: 25 μm thick) support was subjected to alkaline saponification treatment. Specifically, the support was immersed in a 1.5 N sodium hydroxide aqueous solution at 55°C for 2 minutes, then washed in a water bath at room temperature, and further neutralized with 0.1 N sulfuric acid at 30°C. After neutralization, the support was washed in a water bath at room temperature and further dried with hot air at 100°C to obtain a polarizer protective film. A 60 μm thick roll of polyvinyl alcohol (PVA) film was continuously stretched longitudinally in an iodine aqueous solution and dried to obtain a polarizer with a thickness of 13 μm. The luminous efficiency-corrected single-unit transmittance of the polarizer was 43%. At this time, the absorption axis direction and the longitudinal direction of the polarizer coincided. A linear polarizer was fabricated by attaching the polarizer protective film to one side of the polarizer using the PVA adhesive described below.

[0196] (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 to obtain an aqueous solution.

[0197] (Fabrication of circular polarizing plates) The surface of the optically anisotropic layer (1a) of the long optical film (1a-1b-1c-1d) prepared above and the surface of the polarizer of the long linear polarizing plate prepared above (the side opposite the polarizer protective film) were continuously bonded together using an ultraviolet-curing adhesive. In this manner, a circular polarizer (P1) consisting of optical films (1a-1b-1c-1d) and a linear polarizer was fabricated. At this time, the polarizer protective film, polarizer, optical anisotropy layer (1a), optical anisotropy layer (1b), optical anisotropy layer (1c), and optical anisotropy layer (1d) were stacked in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optical anisotropy layer (1b) was 76°. The angle between the in-plane slow axis of the optical anisotropy layer (1b) and the in-plane slow axis of the optical anisotropy layer (1c) on the optical anisotropy layer (1b) side surface was 0°. The twist angle of the liquid crystal compound in the optical anisotropy layer (1c) was 81°. The angle between the polarizer absorption axis and the in-plane slow axis of the optical anisotropy layer (1c) on the optical anisotropy layer (1d) side surface was 5°.

[0198] <Example 2> A long cellulose acylate film was prepared in the same manner as in Example 1 above, and an orientation film coating solution 2 with the following composition was continuously applied to the surface that had undergone alkali saponification treatment using a #14 wire bar. The resulting coating film was dried with hot air at 60°C for 60 seconds, and then with hot air at 100°C for 120 seconds to obtain the orientation film 2.

[0199] -------------------------------------------------- Orientation film coating solution 2 -------------------------------------------------- 10 parts by mass of the following polyvinyl alcohol Water 371 parts by mass 119 parts by mass of methanol Glutaraldehyde (crosslinking agent) 0.5 parts by mass Citrate ester (manufactured by Sankyo Chemical Co., Ltd.) 0.175 parts by mass --------------------------------------------------

[0200] Polyvinyl alcohol

[0201] [ka]

[0202] (Formation of optically anisotropic layer (2a)) On the alignment film 2 described above, an optically anisotropic layer-forming composition (2a) 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 hot air at 110°C for 2 minutes to dry the solvent and mature the alignment of the disc-shaped liquid crystal compound. Subsequently, the obtained composition layer was irradiated with UV light (500 mJ / cm²) at 80°C. 2 The orientation of the liquid crystal compound was fixed by performing the following procedure, and an optical anisotropy layer (2a) corresponding to the first optical anisotropy layer was formed. The thickness of the optically anisotropic layer (2a) was 0.3 μm. Furthermore, 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 40 nm. The average inclination angle of the disc-shaped liquid crystal compound's disc surface relative to the film surface was 0°, confirming that it was oriented horizontally to the film surface.

[0203] -------------------------------------------------- Composition for forming optically anisotropic layer (2a) -------------------------------------------------- 180 parts by mass of the above-mentioned disc-shaped liquid crystal compound 20 parts by mass of the above-mentioned disc-shaped liquid crystal compound 2 0.21 parts by mass of the above fluorine-containing compound C 0.50 parts by mass of the polymer (A) below Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 10 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by BASF) 3.0 parts by mass Methyl ethyl ketone 200 parts by mass --------------------------------------------------

[0204] Polymer (A) (In the formula, the numerical values ​​listed for each repeating unit represent the content (mass %) of each repeating unit relative to the total number of repeating units.)

[0205] [ka]

[0206] (Formation of optically anisotropic layer (1b)) The optically anisotropic layer (2a) prepared as described 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 rotation represented as a positive value, the rotation axis of the rubbing roller is at -14°. In other words, the position of the rotation axis of the rubbing roller is the position obtained by rotating 76° clockwise with respect to the longitudinal direction of the film.

[0207] The optically anisotropic layer-forming composition (1b) was applied to the optically anisotropic layer (2a) that had undergone the rubbing treatment using a Gieser coating machine to form a composition layer. Subsequently, the obtained composition layer was heated with 110°C hot air for 2 minutes to dry the solvent and allow the disc-shaped liquid crystal compound to be oriented and matured. Then, the obtained composition layer was irradiated with UV light (500 mJ / cm²) at 80°C. 2 The orientation of the liquid crystal compound was fixed by performing the following procedure, and an optical anisotropy layer (1b) corresponding to the second optical anisotropy layer was formed. The thickness of the optically anisotropic layer (1b) was 1.1 μm. The retardation at a wavelength of 550 nm was 168 nm. The average tilt angle of the disc surface of the disc-shaped liquid crystal compound with respect to the film surface was 90°, confirming that it was oriented perpendicular to the film surface. Furthermore, the angle of the in-plane slow axis of the optically anisotropic layer (1b) 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 direction of the optically anisotropic layer (1b) was -14° when viewed from the optically anisotropic layer (1b) side.

[0208] A laminate (2a-1b) was fabricated by laminating an optically anisotropic layer (2a) and an optically anisotropic layer (1b) on a cellulose acylate film using the above procedure. The difference in refractive index between the average refractive index of the optically anisotropic layer (2a) and the average refractive index of the optically anisotropic layer (1b) was within 0.05.

[0209] The surface side of the optically anisotropic layer (1b) of the laminate (2a-1b) formed on the long cellulose acylate film prepared as described above and the surface side of the optically anisotropic layer (1c) of the laminate (1c-1d) formed on the long cellulose acylate film prepared in Example 1 were bonded together using an ultraviolet-curing adhesive in a continuous machine, such that the angle between the in-plane slow axis of the optically anisotropic layer (1b) and the in-plane slow axis of the surface side of the optically anisotropic layer (1c) was 0°. Furthermore, as the UV-curing adhesive, an adhesive was used in which a high-refractive-index monomer was added to an acrylic compound to control the refractive index after curing to 1.58. The difference in refractive index between the adhesive layer and the adjacent optically anisotropic layer, and between the adhesive layer and the adhesive layer, was both within 0.05. Next, the cellulose acylate film and alignment film 2 on the optically anisotropic layer (2a) side were peeled off, exposing the surface of the optically anisotropic layer (2a) that had been in contact with the alignment film 2. In this way, an optical film (2a-1b-1c-1d) was obtained in which the optically anisotropic layer (1d), optically anisotropic layer (1c), optically anisotropic layer (1b), and optically anisotropic layer (2a) were laminated in this order on a long cellulose acylate film.

[0210] (Fabrication of circular polarizing plates) The surface of the optical anisotropic layer (2a) of the long optical film (2a-1b-1c-1d) prepared above and the surface of the polarizer of the long linear polarizing plate prepared in Example 1 (the side opposite the polarizer protective film) were continuously bonded together using an ultraviolet-curing adhesive whose cured refractive index was controlled to 1.53. The difference in refractive index between the average refractive index of adjacent optical anisotropic layers and the average refractive index of the adhesive layer was 0.08 or less. Next, the cellulose acylate film on the optically anisotropic layer (1d) side was peeled off, exposing the surface of the optically anisotropic layer (1d) that had been in contact with the cellulose acylate film. In this manner, a circular polarizer (P2) consisting of optical films (2a-1b-1c-1d) and a linear polarizer was fabricated. At this time, the polarizer protective film, polarizer, optical anisotropy layer (2a), optical anisotropy layer (1b), optical anisotropy layer (1c), and optical anisotropy layer (1d) were stacked in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optical anisotropy layer (1b) was 76°. The angle between the in-plane slow axis of the optical anisotropy layer (1b) and the in-plane slow axis of the optical anisotropy layer (1c) on the optical anisotropy layer (1b) side surface was 0°. The twist angle of the liquid crystal compound in the optical anisotropy layer (1c) was 81°. The angle between the polarizer absorption axis and the in-plane slow axis of the optical anisotropy layer (1c) on the optical anisotropy layer (1d) side surface was 5°.

[0211] <Example 3> (Formation of optically anisotropic layer (3a)) In forming the optically anisotropic layer (1d) of Example 1, an optically anisotropic layer (3a) corresponding to the first optically anisotropic layer, which has orientation control capability on its surface, was formed in the same manner except for changing the thickness of the composition layer. The thickness of the formed optically anisotropic layer (3a) was 0.4 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 -45 nm. The average tilt angle of the rod-shaped liquid crystal compound in the direction of the long axis with respect to the film surface was 90°, confirming that it was oriented perpendicular to the film surface.

[0212] (Formation of optically anisotropic layer (3b)) Next, an optically anisotropic layer-forming composition (3b) containing a rod-shaped liquid crystal compound with the following composition was applied onto the optically anisotropic layer (3a) prepared above using a Gieser coating machine, and heated with 80°C hot air for 60 seconds. Subsequently, the resulting composition layer was irradiated with UV light (500 mJ / cm²) at 80°C. 2 The orientation of the liquid crystal compound was fixed by performing the following procedure, and an optical anisotropy layer (3b) corresponding to the second optical anisotropy layer was formed. The thickness of the optically anisotropic layer (3b) was 1.2 μm. The in-plane retardation at a wavelength of 550 nm was 168 nm. The average tilt angle of the rod-shaped liquid crystal compound with respect to the film plane in the direction of the long axis was 0°, confirming that it was oriented horizontally to the film plane (homogenous orientation). Furthermore, assuming the film width direction was 0° (the long direction being 90° counterclockwise and -90° clockwise), the in-plane slow axis direction of the optically anisotropic layer (3b) was 104° when viewed from the optically anisotropic layer (3b) side.

[0213] -------------------------------------------------- Composition for forming optically anisotropic layer (3b) -------------------------------------------------- 100 parts by mass of the above rod-shaped liquid crystal compound (A) 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 0.08 parts by mass of the above fluorine-containing compound C Methyl ethyl ketone 156 parts by mass --------------------------------------------------

[0214] Following the procedure described above, a laminate (3a-3b) was fabricated in which an optically anisotropic layer (3a) and an optically anisotropic layer (3b) were directly laminated on a long cellulose acylate film. The difference in refractive index between the average refractive index of the optically anisotropic layer (3a) and the average refractive index of the optically anisotropic layer (3b) was within 0.05. Furthermore, when the surface of the optically anisotropic layer (3a) in contact with the optically anisotropic layer (3b) was examined using the method described above, it was confirmed that a photo-oriented polymer was present.

[0215] (Formation of optically anisotropic layer (3d)) In forming the optical anisotropic layer (2a) of Example 2, an optical anisotropic layer (3d) corresponding to the fourth optical anisotropic layer was formed in the same manner, except that the thickness of the composition layer was changed. The thickness of the optically anisotropic layer (3a) was 0.4 μm. Furthermore, 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 55 nm. The average inclination angle of the disc-shaped liquid crystal compound's disc surface relative to the film surface was 0°, confirming that it was oriented horizontally to the film surface.

[0216] (Formation of optically anisotropic layer (3c)) The optically anisotropic layer (3d) prepared as described 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 85°. 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 5°. In other words, the position of the rotation axis of the rubbing roller is the position obtained by rotating 85° counterclockwise with respect to the longitudinal direction of the film.

[0217] On the optically anisotropic layer (3d) that had undergone the rubbing process described above, the following optically anisotropic layer-forming composition (3c) was applied using a Gieser coating machine to form a composition layer. Subsequently, the obtained composition layer was heated with hot air at 110°C for 2 minutes to dry the solvent and allow the disc-shaped liquid crystal compound to be oriented and matured. Then, the obtained composition layer was irradiated with UV light (500 mJ / cm²) at 80°C. 2 The orientation of the liquid crystal compound was fixed by performing the following procedure, and an optical anisotropy layer (3c) corresponding to the third optical anisotropy layer was formed. The optically anisotropic layer (3c) had a thickness of 1.1 μm, Δnd at a wavelength of 550 nm was 164 nm, and the torsion angle of the liquid crystal compound was 81°. When the width direction of the film was set to 0° (the longitudinal direction to 90°), the in-plane slow axis direction, when viewed from the optically anisotropic layer (3c) side, was 76° on the air side and -5° on the side in contact with the optically anisotropic layer (3d). The in-plane slow-moving axis direction of the optical anisotropic layer is expressed by observing a circular polarizer from the surface side of the optical anisotropic layer, with the substrate width direction being the reference 0°, and clockwise (right-handed) rotation being negative and counterclockwise (left-handed) rotation being positive.

[0218] -------------------------------------------------- Composition for forming optically anisotropic layer (3c) -------------------------------------------------- 180 parts by mass of the above-mentioned disc-shaped liquid crystal compound 20 parts by mass of the above-mentioned disc-shaped liquid crystal compound 2 0.55 parts by mass of the above-mentioned orientation agent for the interface of the orientation film. 0.1 parts by mass of the above-mentioned fluorine-containing compound A 0.05 parts by mass of the above-mentioned fluorine-containing compound B 0.21 parts by mass of the above fluorine-containing compound C The following right-handed chiral agent (L2): 0.30 parts by mass Ethylene oxide-modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 10 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by BASF) 3.0 parts by mass Methyl ethyl ketone 200 parts by mass --------------------------------------------------

[0219] Right-handed chiral agent (L2)

[0220] [ka]

[0221] A laminate (3c-3d) was fabricated by laminating an optically anisotropic layer (3d) and an optically anisotropic layer (3c) on a cellulose acylate film using the above procedure. The difference in refractive index between the average refractive index of the optically anisotropic layer (3c) and the average refractive index of the optically anisotropic layer (3d) was within 0.05.

[0222] The surface side of the optically anisotropic layer (3b) of the laminate (3a-3b) formed on the long cellulose acylate film prepared above and the surface side of the optically anisotropic layer (3c) of the laminate (3c-3d) formed on the long cellulose acylate film prepared above were bonded together using an ultraviolet-curing adhesive in a continuous machine, such that the angle between the in-plane slow axis of the optically anisotropic layer (3b) and the in-plane slow axis of the surface side of the optically anisotropic layer (3c) was 0°. Furthermore, as the UV-curing adhesive, an adhesive was used in which a high-refractive-index monomer was added to an acrylic compound to control the refractive index after curing to 1.58. The difference in refractive index between the adhesive layer and the adjacent optically anisotropic layer, and between the adhesive layer and the adhesive layer, was both within 0.05. Next, the cellulose acylate film on the optically anisotropic layer (3a) side was peeled off, exposing the surface of the optically anisotropic layer (3a) that had been in contact with the cellulose acylate film. In this way, an optical film (3a-3b-3c-3d) was obtained in which the optically anisotropic layer (3d), optically anisotropic layer (3c), optically anisotropic layer (3b), and optically anisotropic layer (3a) were laminated in this order on a long cellulose acylate film.

[0223] (Fabrication of circular polarizing plates) The surface of the optical anisotropic layer (3a) of the long optical film (3a-3b-3c-3d) prepared above and the surface of the polarizer of the long linear polarizer prepared in Example 1 (the side opposite the polarizer protective film) were continuously bonded together using an ultraviolet-curing adhesive whose cured refractive index was controlled to 1.53. The difference in refractive index between the average refractive index of adjacent optical anisotropic layers and the average refractive index of the adhesive layer was 0.08 or less. Next, the cellulose acylate film on the optically anisotropic layer (3d) side was peeled off, exposing the surface of the optically anisotropic layer (3d) that had been in contact with the cellulose acylate film. In this manner, a circular polarizer (P3) consisting of optical films (3a-3b-3c-3d) and a linear polarizer was fabricated. At this time, the polarizer protective film, polarizer, optical anisotropy layer (3a), optical anisotropy layer (3b), optical anisotropy layer (3c), and optical anisotropy layer (3d) were stacked in this order, and the angle between the absorption axis of the polarizer and the slow axis of the optical anisotropy layer (3b) was 14°. The angle between the in-plane slow axis of the optical anisotropy layer (3b) and the in-plane slow axis of the optical anisotropy layer (3c) on the optical anisotropy layer (3b) side surface was 0°. The twist angle of the liquid crystal compound in the optical anisotropy layer (3c) was 81°. The angle between the polarizer absorption axis and the in-plane slow axis of the optical anisotropy layer (3c) on the optical anisotropy layer (3d) side surface was 95°.

[0224] In the circular polarizer (P3), when the circular polarizer (P3) is observed from the optical anisotropy layer side, the in-plane slow axis of the optical anisotropy layer (3b) is rotated 14° counterclockwise with respect to the absorption axis of the polarizer, and the torsion direction of the liquid crystal compound in the optical anisotropy layer (3c) is clockwise. The torsional direction of the liquid crystal compound is determined by observing the circular polarizer (P3) from the optically anisotropic layer side, and then determining whether it is clockwise or counterclockwise based on the in-plane slow axis on the surface of the optically anisotropic layer (3c) on the optically anisotropic layer (3d) side (the surface closer to the viewer).

[0225] <Example 4> (Formation of optically anisotropic layer (4a)) A composition for forming an optically anisotropic layer (4a) containing a disc-shaped liquid crystal compound with the following composition was applied to a cellulose triacetate film TG40 (manufactured by Fujifilm Corporation: 40 μm thick) using a Gieser coating machine to form a composition layer. Then, with both ends of the film held, 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 (110°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 90 seconds. Next, the obtained film was heated with hot air at 116°C for 1 minute, and while purging with nitrogen to maintain an atmosphere with an oxygen concentration of 100 ppm by volume or less, it was irradiated with a 365 nm UV-LED at a dose of 150 mJ / cm². 2 The surface was irradiated with ultraviolet light. Subsequently, the resulting coating was annealed with hot air at 115°C for 25 seconds to form an optical anisotropic layer (4a) corresponding to the first optical anisotropic layer. The resulting optically anisotropic layer (4a) was exposed to UV light (ultra-high pressure mercury lamp; UL750; manufactured by HOYA) at room temperature, through a wire grid polarizer, at a rate of 7.9 mJ / cm². 2 By irradiating the surface with a wavelength of 313 nm, the ability to control orientation was imparted to the surface. The thickness of the formed optically anisotropic layer (4a) was 1.0 μm. The in-plane retardation Re at a wavelength of 550 nm was 0 nm, and the thickness-direction retardation Rth at a wavelength of 550 nm was 40 nm. The average inclination angle of the disc surface of the disc-shaped liquid crystal compound with respect to the film surface was 0°, confirming that it was oriented horizontally with respect to the film surface.

[0226] -------------------------------------------------- Composition for forming optically anisotropic layer (4a) -------------------------------------------------- 18 parts by mass of the above-mentioned disc-shaped liquid crystal compound 2 parts by mass of the above-mentioned disc-shaped liquid crystal compound 2 The following disc-shaped liquid crystal compound 3: 95.6 parts by mass 14.0 parts by mass of the following polymerizable monomer 1 3.0 parts by mass of the polymerization initiator S-1 (oxime type) mentioned above 3.0 parts by mass of the above photoacid generator D-1 The following photo-oriented polymer A-2: 1.0 parts by mass Triisopropylamine 0.2 parts by mass o-Xylene 634 parts by mass --------------------------------------------------

[0227] Disc-shaped liquid crystal compound 3

[0228] [ka]

[0229] Polymerizable monomer 1

[0230] [ka]

[0231] Photo-oriented polymer A-2 (The letters within each repeating unit represent the mass percentage of each repeating unit relative to the total number of repeating units. The percentages were 37% by mass, 37% by mass, and 26% by mass from left to right. The weight-average molecular weight was 73,000.)

[0232] [ka]

[0233] (Formation of optically anisotropic layer (4b)) Next, an optical anisotropic layer-forming composition (4b) containing a disc-shaped liquid crystal compound with the following composition was applied to the optical anisotropic layer (4a) prepared above using a Gieser coating machine, and heated with hot air at 95°C for 120 seconds. Subsequently, the resulting composition layer was irradiated with UV light (100 mJ / cm²) at 95°C. 2 The orientation of the liquid crystal compound was fixed by performing the following procedure, and an optical anisotropy layer (4b) corresponding to the second optical anisotropy layer was formed. The optically anisotropic layer (4b) had a thickness of 1.5 μm, and its Δnd at a wavelength of 550 nm was 153 nm. The average inclination angle of the disc surface of the disc-shaped liquid crystal compound with respect to the film surface was 90°, confirming that it was oriented perpendicular to the film surface. Furthermore, the angle of the in-plane slow axis of the optically anisotropic layer (4b) 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 direction of the optically anisotropic layer (4b) was -14° when viewed from the optically anisotropic layer (4b) side.

[0234] -------------------------------------------------- Composition for forming optically anisotropic layer (4b) -------------------------------------------------- 180 parts by mass of the above-mentioned disc-shaped liquid crystal compound 20 parts by mass of the above-mentioned disc-shaped liquid crystal compound 2 1.8 parts by mass of the above-mentioned orientation film interface orientation agent 1 10.0 parts by mass of the polymerizable monomer 1 mentioned above. 5.0 parts by mass of the above polymerization initiator S-1 (oxime type) 0.1 parts by mass of the above-mentioned fluorine-containing compound A 0.2 parts by mass of the following fluorine-containing compound D 0.1 parts by mass of the following fluorine-containing compound E The following defoaming agent: 1 2.1 parts by mass Methyl ethyl ketone 419 parts by mass --------------------------------------------------

[0235] Fluorine-containing compound D (The numerical values ​​within each repeating unit represent the content (mass%) relative to the total number of repeating units; the content of the repeating unit on the left was 52 mass%, and the content of the repeating unit on the right was 48 mass%).

[0236] [ka]

[0237] Fluorine-containing compound E (The content of the repeating units on the left was 36% by mass, and the content of the repeating units on the right was 64% by mass.)

[0238] [ka]

[0239] Antifoaming agent 1

[0240] [ka]

[0241] Following the procedure described above, a laminate (4a-4b) was fabricated in which an optically anisotropic layer (4a) and an optically anisotropic layer (4b) were directly laminated on a cellulose acylate film TG40. The difference between the average refractive index of the optically anisotropic layer (4a) and the average refractive index of the optically anisotropic layer (4b) was 0.05 or less.

[0242] (Formation of optically anisotropic layer (4d)) In forming the optically anisotropic layer (1d) of Example 1, an optically anisotropic layer (4d), which corresponds to the fourth optically anisotropic layer, was formed in the same manner except for changing the thickness of the composition layer. The thickness of the formed optically anisotropic layer (4d) was 0.7 μm. The in-plane retardation Re at a wavelength of 550 nm was 0 nm, and the retardation Rth in the thickness direction at a wavelength of 550 nm was -85 nm. The average tilt 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.

[0243] (Formation of optically anisotropic layer (4c)) Next, on the optically anisotropic layer (4d) prepared above, an optically anisotropic layer (4c), which corresponds to the third optically anisotropic layer, was formed in the same manner as in the formation of the optically anisotropic layer (1c) of Example 1, except that the thickness of the composition layer was changed. The optically anisotropic layer (4c) had a thickness of 1.25 μm, Δnd at a wavelength of 550 nm was 170 nm, and the torsion angle of the liquid crystal compound was 85°. When the width direction of the film was set to 0° (the longitudinal direction to 90°), when viewed from the optically anisotropic layer (4c) side, the in-plane slow axis direction (orientation axis angle of the liquid crystal compound) was 10° on the air side and 95° on the side in contact with the optically anisotropic layer (4d). The in-plane slow-moving axis direction of the optical anisotropic layer is expressed by observing the substrate from the surface side of the optical anisotropic layer, with the substrate width direction being the reference 0°, and clockwise (rightward) rotation being negative and counterclockwise (leftward) rotation being positive.

[0244] Following the procedure described above, a laminate (4c-4d) was fabricated in which an optically anisotropic layer (4d) and an optically anisotropic layer (4c) were directly laminated onto a long cellulose acylate film. The difference in refractive index between the average refractive index of the optically anisotropic layer (4c) and the average refractive index of the optically anisotropic layer (4d) was within 0.05.

[0245] The surface side of the optically anisotropic layer (4b) of the laminate (4a-4b) formed on the cellulose acylate film TG40 prepared above and the surface side of the optically anisotropic layer (4c) of the laminate (4c-4d) formed on the long cellulose acylate film prepared above were bonded together using an ultraviolet-curing adhesive in a continuous machine, such that the in-plane slow axis of the surface side of the optically anisotropic layer (4b) of the laminate (4a-4b) was +4° with respect to the in-plane slow axis of the surface side of the optically anisotropic layer (4c) of the laminate (4c-4d). The in-plane slow-moving axis direction of the optical anisotropic layer is expressed by observing the laminate from the surface side of the optical anisotropic layer (4a), with the substrate width direction being the reference 0°, and clockwise (right-handed) rotation being negative and counterclockwise (left-handed) rotation being positive. As an UV-curing adhesive, we used an adhesive in which a high-refractive-index monomer was added to an acrylic compound to control the refractive index after curing to 1.58. The difference in refractive index between the adhesive layer and the adjacent optically anisotropic layer, and between the adhesive layer and the adhesive layer, was both within 0.05. Next, the cellulose acylate film on the optically anisotropic layer (4a) side was peeled off from the optically anisotropic layer (4a), exposing the surface of the optically anisotropic layer (4a) that had been in contact with the cellulose acylate film. In this way, an optical film (4a-4b-4c-4d) was obtained in which the optically anisotropic layer (4d), optically anisotropic layer (4c), optically anisotropic layer (4b), and optically anisotropic layer (4a) were laminated in this order on a long cellulose acylate film.

[0246] (Fabrication of circular polarizing plates) The surface of the optical anisotropic layer (4a) of the long optical film (4a-4b-4c-4d) prepared above and the surface of the polarizer of the long linear polarizer prepared in Example 1 (the side opposite the polarizer protective film) were continuously bonded together using an ultraviolet-curing adhesive whose cured refractive index was controlled to 1.53 in the same manner as described above. The difference in refractive index between the average refractive index of adjacent optical anisotropic layers and the average refractive index of the adhesive layer was 0.08 or less. Next, the cellulose acylate film on the optically anisotropic layer (4d) side was peeled off, exposing the surface of the optically anisotropic layer (4d) that had been in contact with the cellulose acylate film. In this manner, a circular polarizer (P4) consisting of optical films (4a-4b-4c-4d) and a linear polarizer was fabricated. At this time, the polarizer protective film, polarizer, optical anisotropy layer (4a), optical anisotropy layer (4b), optical anisotropy layer (4c), and optical anisotropy layer (4d) were stacked in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optical anisotropy layer (4b) was 76°. The angle between the in-plane slow axis of the optical anisotropy layer (4b) and the in-plane slow axis of the optical anisotropy layer (4c) on the optical anisotropy layer (4b) side surface was 4°. The twist angle of the liquid crystal compound in the optical anisotropy layer (4c) was 85°. The angle between the polarizer absorption axis and the in-plane slow axis of the optical anisotropy layer (4c) on the optical anisotropy layer (4d) side surface was 5°.

[0247] <Example 5> Optical anisotropic layer (1b), optical anisotropic layer (1c), optical anisotropic layer (1d), and circular polarizer were fabricated in the same manner as in Example 1, except that optical anisotropic layer (1a), which is made of cellulose acylate film corresponding to the first optical anisotropic layer in Example 1, was replaced with cellulose acetate TJ25 (manufactured by Fujifilm Corporation: thickness 25 μm) (optical anisotropic layer (5a)).

[0248] <Example 6> An optical anisotropic layer (1b), an optical anisotropic layer (1c), an optical anisotropic layer (1d), and a circular polarizer were fabricated in the same manner as in Example 1, except that the optical anisotropic layer (1a), which is made of a cellulose acylate film and corresponds to the first optical anisotropic layer in Example 1, was replaced with the following optical anisotropic layer (6a). (Preparation of cellulose acylate film) The following composition 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 a dope. The solid content concentration of the dope was 19.0% by mass, and the solvent of the dope was methylene chloride / methanol = 87 / 13 (by mass).

[0249] ------------------------------------------------------------------ Cellulose acylate dope ------------------------------------------------------------------ Cellulose acylate (acetyl substitution degree 2.88) 100.0 parts by mass Ester oligomer (dicarboxylic acid: adipic acid / phthalic acid = 3 / 7, ethylene glycol, acetyl group-terminated, molecular weight 1000) 10.0 parts by mass Polarizer durability improver (compound with the following structural formula) 4.0 parts by mass UV absorber (compound with the following structural formula) 2.0 parts by mass Retardation enhancer (compound with the following structural formula) 3.0 parts by mass Solvent (methylene chloride / methanol) ------------------------------------------------------------------

[0250] Polarizer durability improver

[0251] [ka]

[0252] UV absorber

[0253] [ka]

[0254] Retardation enhancer

[0255] [ka]

[0256] The dope prepared as described above was cast using a band deposition machine. The dope was cast from the die onto a metal support heated to 20°C, and then the resulting web (film) was peeled off. The band was made of stainless steel (SUS).

[0257] The web (film) obtained by casting was peeled from the band with a solvent content of approximately 20% by mass. During film transport, it was dried while being stretched 1.1 times in the transverse direction, with a residual solvent content of 3-15%. Subsequently, it was further dried by transporting it between rolls in a heat treatment apparatus to produce a cellulose acylate film with a thickness of 25 μm. The obtained cellulose acylate film exhibited an in-plane retardation of 1 nm at a wavelength of 550 nm and a thickness-direction retardation of 30 nm at a wavelength of 550 nm.

[0258] <Example 7> Using adhesive A, which is the UV-curing adhesive used in Example 6, optical anisotropy layers (6a), optical anisotropy layer (1b), optical anisotropy layer (1c), optical anisotropy layer (1d), and a circular polarizer were fabricated, all consisting of a cellulose acylate film corresponding to the first optical anisotropy layer. The surface side of the optically anisotropic layer (1b) of the laminate (6a-1b) formed on the long cellulose acylate film prepared in Example 6 and the surface side of the optically anisotropic layer (1c) of the laminate (1c-1d) formed on the long cellulose acylate film prepared in Example 1 were bonded together using adhesive A in a continuous machine, such that the angle between the in-plane slow axis of the optically anisotropic layer (1b) and the in-plane slow axis of the surface side of the optically anisotropic layer (1c) was 0°. The adhesive A described above had its refractive index controlled to 1.54, and an adhesive layer with a thickness of 15 μm was formed. The difference in refractive index between the adhesive and the average refractive index of the adjacent optically anisotropic layer in the axial direction was both within 0.08. Next, the cellulose acylate film on the optically anisotropic layer (1d) side was peeled off, exposing the surface of the optically anisotropic layer (1d) that had been in contact with the cellulose acylate film. In this way, an optical film (6a-1b-1c-1d) was obtained in which an optically anisotropic layer (6a) made of a long cellulose acylate film was laminated with an optically anisotropic layer (1b), an optically anisotropic layer (1c), and an optically anisotropic layer (1d) in that order.

[0259] (Fabrication of circular polarizing plates) The surface of the optically anisotropic layer (6a) of the long optical film (6a-1b-1c-1d) prepared above and the surface of the polarizer of the long linear polarizing plate prepared above (the side opposite the polarizer protective film) were continuously bonded together using the PVA adhesive described above. In this manner, a circular polarizer (P7) consisting of optical films (6a-1b-1c-1d) and a linear polarizer was fabricated. At this time, the polarizer protective film, polarizer, optical anisotropy layer (6a), optical anisotropy layer (1b), optical anisotropy layer (1c), and optical anisotropy layer (1d) were stacked in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optical anisotropy layer (1b) was 76°. The angle between the in-plane slow axis of the optical anisotropy layer (1b) and the in-plane slow axis of the optical anisotropy layer (1c) on the optical anisotropy layer (1b) side surface was 0°. The twist angle of the liquid crystal compound in the optical anisotropy layer (1c) was 81°. The angle between the polarizer absorption axis and the in-plane slow axis of the optical anisotropy layer (1c) on the optical anisotropy layer (1d) side surface was 5°.

[0260] <Example 8> Using adhesive B described below, instead of the UV-curing adhesive used in Example 6, optical anisotropy layers (6a), optical anisotropy layer (1b), optical anisotropy layer (1c), optical anisotropy layer (1d), and a circular polarizer were fabricated, all consisting of a cellulose acylate film corresponding to the first optical anisotropy layer. The surface side of the optically anisotropic layer (1b) of the laminate (6a-1b) formed on the long cellulose acylate film prepared in Example 6 and the surface side of the optically anisotropic layer (1c) of the laminate (1c-1d) formed on the long cellulose acylate film prepared in Example 1 were bonded together using adhesive B in a continuous machine, such that the angle between the in-plane slow axis of the optically anisotropic layer (1b) and the in-plane slow axis of the surface side of the optically anisotropic layer (1c) was 0°. The above adhesive B contains UV-2 as an ultraviolet absorber, as described in International Publication WO2021 / 006097, and its refractive index is controlled to 1.54, forming an adhesive layer with a thickness of 25 μm. The difference in refractive index between the adhesive and the average refractive index in the axial direction of the adjacent optical anisotropy layer was both within 0.08. Next, the cellulose acylate film on the optically anisotropic layer (1d) side was peeled off, exposing the surface of the optically anisotropic layer (1d) that had been in contact with the cellulose acylate film. In this way, an optical film (6a-1b-1c-1d) was obtained in which an optically anisotropic layer (6a) made of a long cellulose acylate film was laminated with an optically anisotropic layer (1b), an optically anisotropic layer (1c), and an optically anisotropic layer (1d) in that order.

[0261] (Fabrication of circular polarizing plates) The surface of the optically anisotropic layer (6a) of the long optical film (6a-1b-1c-1d) prepared above and the surface of the polarizer of the long linear polarizing plate prepared above (the side opposite the polarizer protective film) were continuously bonded together using the PVA adhesive described above. In this manner, a circular polarizer (P7) consisting of optical films (6a-1b-1c-1d) and a linear polarizer was fabricated. At this time, the polarizer protective film, polarizer, optical anisotropy layer (6a), optical anisotropy layer (1b), optical anisotropy layer (1c), and optical anisotropy layer (1d) were stacked in this order, and the angle between the absorption axis of the polarizer and the in-plane slow axis of the optical anisotropy layer (1b) was 76°. The angle between the in-plane slow axis of the optical anisotropy layer (1b) and the in-plane slow axis of the optical anisotropy layer (1c) on the optical anisotropy layer (1b) side surface was 0°. The twist angle of the liquid crystal compound in the optical anisotropy layer (1c) was 81°. The angle between the polarizer absorption axis and the in-plane slow axis of the optical anisotropy layer (1c) on the optical anisotropy layer (1d) side surface was 5°. Furthermore, the transmittance of the circular polarizer P7 at 380 nm was less than 1%. The transmittance was measured using a Shimadzu UV-3150 spectrophotometer.

[0262] <Comparative Example 1> An optical film was prepared by directly laminating, in the same manner as in Example 1 of Japanese Patent No. 5960743, an optically anisotropic layer (h1) consisting of vertically oriented disc-shaped liquid crystals and an optically anisotropic layer (h2) consisting of torsionally oriented disc-shaped liquid crystals, in that order, onto a long cellulose acylate film. At this time, the in-plane retardation of the optically anisotropic layer (h1) at a wavelength of 550 nm was 181 nm, and when the film width direction was 0° (longitudinal direction was 90°), the in-plane slow phase axis direction when viewed from the optically anisotropic layer (h1) side was -13°. Furthermore, the Δnd of the optically anisotropic layer (h2) at a wavelength of 550 nm was 172 nm, the twist angle of the liquid crystal compound was 81°, and when the film width direction was 0° (longitudinal direction was 90°), the in-plane slow phase axis direction when viewed from the optically anisotropic layer (h2) side was -94° on the air side and -13° on the side in contact with the cellulose acylate film. The surface of the cellulose acylate film of the laminate (h1-h2) formed on the long cellulose acylate film prepared above and the surface of the polarizer of the long linear polarizer prepared above (the side opposite the polarizer protective film) were continuously bonded together using an ultraviolet-curing adhesive. In this way, a circular polarizer (PH) was prepared.

[0263] <Fabrication of Organic EL Display Devices> (Implementation on display devices) A Samsung GALAXY S4 equipped with an organic EL panel was disassembled, the circular polarizer was peeled off, and the circular polarizers prepared in Examples 1-6 and Comparative Example 1 were attached to the display device using a pressure-sensitive adhesive so that the polarizer protective film was positioned on the outside.

[0264] <Measuring refractive index> Samples were prepared by transferring each optically anisotropic layer used in each example and comparative example onto glass using an adhesive. The reflectance spectra of the optically anisotropic layers were measured using a reflectance spectrometer FE3000 (manufactured by Otsuka Electronics Co., Ltd.), and the average refractive index was calculated from the obtained reflectance spectra. In calculating the average refractive index, assuming that the refractive indices at both interfaces of the optically anisotropic layer are equal, the average refractive index n at a wavelength of 550 nm was determined by fitting the reflectance spectra to the following Cauchy dispersion formula using the least squares method. Here, C1, C2, and C3 are parameters of the n-Cauchy model, λ is the wavelength, and k is the attenuation coefficient. In addition, the thickness of the samples from which the reflectance spectra were measured was measured using a scanning electron microscope (Hitachi High-Technologies Corporation, S-4800), and this value was used as the thickness during fitting. As mentioned above, the average refractive index calculated by the above method corresponds to the average refractive index ((nx+ny) / 2) expressed by the above formula (N1).

[0265]

number

[0266] The average refractive index of the adhesive layer and the tack layer was also measured using the same method as described above.

[0267] [Evaluation of display performance] (Front direction) The fabricated organic EL display device was shown in black, observed from the front under bright light, and the color rendering was evaluated according to the following criteria. The results are shown in Table 1 below. A: No color tint is visible at all, or only a slight tint is visible. (Acceptable) B: A slight tint is visible, but the reflected light is minimal and does not pose a problem for use. (Acceptable) C: The color tint is visible, and the reflected light is significant; this is unacceptable.

[0268] (Diagonal direction) The fabricated organic EL display device was shown in black, and under bright light conditions, a fluorescent lamp was projected from an extreme angle of 45°, and the reflected light was observed from all directions. The azimuth angle dependence of the color change was evaluated according to the following criteria. The results are shown in Table 1 below. A: No color difference is visible at all, or only a very slight difference is visible. (Acceptable) B: A slight color difference is visible but within an acceptable range, and the reflected light is small, so there are no problems in use. (Acceptable) C: The color difference is visible, and the reflected light is also significant; this is unacceptable.

[0269] [Table 1]

[0270] As shown in Table 1 above, the phase difference film of the present invention was confirmed to be able to suppress the black coloration in the front and oblique directions when used as a circular polarizer in an organic EL display device. On the other hand, the phase difference film of the comparative example was inferior in suppressing the black coloration in the oblique direction when used as a circular polarizer in an organic EL display device. Furthermore, Examples 7 and 8 demonstrated the same effects of the present invention as Example 6. [Explanation of symbols]

[0271] 10A, 10B, 10C, 10D Phase difference film 12A, 12B, 12C, 12D First optical anisotropic layer 14A, 14B, 14C, 14D Second optical anisotropy layer 16A, 16B, 16C, 16D Third optical anisotropy layer 18A, 18B, 18C, 18D: Fourth optical anisotropy layer 20 polarizers 22 Close contact layer 100A, 100B Circular Polarizing Plates

Claims

1. The first optical anisotropy layer, the second optical anisotropy layer, the third optical anisotropy layer, and the fourth optical anisotropy layer are present in this order. The first optical anisotropy layer is a C plate, The second optical anisotropy layer is plate A, The third optically anisotropic layer is a layer in which a liquid crystal compound is fixed in a torsion orientation along a helical axis extending in the thickness direction. The fourth optical anisotropy layer is a C plate, The first optical anisotropic layer is a negative C plate, the second optical anisotropic layer is a negative A plate, the liquid crystal compound in the third optical anisotropic layer is a rod-shaped liquid crystal compound, and the fourth optical anisotropic layer is a positive C plate. A phase difference film in which the angle between the in-plane slow axis of the second optical anisotropy layer and the in-plane slow axis of the third optical anisotropy layer on the surface facing the second optical anisotropy layer is in the range of 0 to 30°.

2. Having a first optical anisotropy layer, a second optical anisotropy layer, a third optical anisotropy layer, and a fourth optical anisotropy layer in this order, The first optical anisotropy layer is a C plate, The second optical anisotropy layer is plate A, The third optically anisotropic layer is a layer in which a liquid crystal compound is fixed in a torsion orientation along a helical axis extending in the thickness direction. The fourth optical anisotropy layer is a C plate, If the first optical anisotropy layer is a negative C plate, the second optical anisotropy layer is a negative A plate, the liquid crystal compound in the third optical anisotropy layer is a rod-shaped liquid crystal compound, and the fourth optical anisotropy layer is a positive C plate. If the first optical anisotropy layer is a positive C plate, the second optical anisotropy layer is a positive A plate, the liquid crystal compound of the third optical anisotropy layer is a disc-shaped liquid crystal compound, and the fourth optical anisotropy layer is a negative C plate. The angle between the in-plane slow axis of the second optical anisotropy layer and the in-plane slow axis of the third optical anisotropy layer on the surface facing the second optical anisotropy layer is in the range of 0 to 30°. A phase difference film having a thickness of 0.1 to 5.0 μm for the first optically anisotropic layer.

3. The phase difference film according to claim 1 or 2, wherein the twist angle of the liquid crystal compound is within the range of 80 ± 30°.

4. The phase difference film according to any one of claims 1 to 3, wherein the absolute value of the retardation in the thickness direction at a wavelength of 550 nm of the first optical anisotropy layer is 5 to 100 nm.

5. The phase difference film according to any one of claims 1 to 4, wherein the in-plane retardation of the second optical anisotropy layer at a wavelength of 550 nm is 120 to 240 nm.

6. A phase difference film according to any one of claims 1 to 5, wherein the value of the product Δnd of the refractive index anisotropy Δn of the third optical anisotropy layer and the thickness d of the third optical anisotropy layer at a wavelength of 550 nm is 120 to 240 nm.

7. The phase difference film according to any one of claims 1 to 6, wherein the absolute value of the retardation in the thickness direction at a wavelength of 550 nm of the fourth optical anisotropy layer is 5 to 100 nm.

8. The first optical anisotropy layer, the second optical anisotropy layer, the third optical anisotropy layer, and the fourth optical anisotropy layer are present in this order. The first optical anisotropy layer and the second optical anisotropy layer are in direct contact or are laminated with an adhesion layer in between. The second optical anisotropy layer and the third optical anisotropy layer are in direct contact or are laminated with an adhesion layer in between. The third optical anisotropy layer and the fourth optical anisotropy layer are in direct contact or are laminated with an adhesion layer in between. The first optical anisotropic layer is a negative C plate, the second optical anisotropic layer is a negative A plate, the third optical anisotropic layer is a layer in which a liquid crystal compound is fixed in a torsion orientation along a helical axis extending in the thickness direction, and the fourth optical anisotropic layer is a positive C plate. A phase difference film that satisfies at least one of the following requirements 1 to 4. Requirement 1: The difference between the average refractive index of the first optical anisotropy layer and the average refractive index of the layer in contact with the surface of the first optical anisotropy layer on the second optical anisotropy layer side is 0.10 or less. Requirement 2: At least one of the differences between the average refractive index of the second optical anisotropy layer and the average refractive index of the layer in contact with the surface of the second optical anisotropy layer on the first optical anisotropy layer side, and the difference between the average refractive index of the second optical anisotropy layer and the average refractive index of the layer in contact with the surface of the second optical anisotropy layer on the third optical anisotropy layer side, is 0.10 or less. Requirement 3: At least one of the differences between the average refractive index of the third optical anisotropy layer and the average refractive index of the layer in contact with the surface of the third optical anisotropy layer on the second optical anisotropy layer side, and the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the layer in contact with the surface of the third optical anisotropy layer on the fourth optical anisotropy layer side, is 0.10 or less. Requirement 4: The difference between the average refractive index of the fourth optical anisotropy layer and the average refractive index of the layer in contact with the surface of the fourth optical anisotropy layer on the third optical anisotropy layer side is 0.10 or less.

9. The first optical anisotropy layer, the second optical anisotropy layer, the third optical anisotropy layer, and the fourth optical anisotropy layer are present in this order. The first optical anisotropy layer is a negative C plate, The second optical anisotropy layer is a negative A plate, The third optically anisotropic layer is a layer in which a liquid crystal compound is fixed in a torsion orientation along a helical axis extending in the thickness direction. The fourth optical anisotropy layer is a positive C plate, At least one of the first optical anisotropy layer and the second optical anisotropy layer, the second optical anisotropy layer and the third optical anisotropy layer, and the third optical anisotropy layer and the fourth optical anisotropy layer are laminated with an adhesion layer in between. A phase difference film in which the difference between the average refractive index of the adhesion layer and the average refractive index of the optical anisotropy layer adjacent to the adhesion layer is 0.10 or less.

10. The second optical anisotropy layer and the third optical anisotropy layer are laminated with an adhesion layer in between. The difference between the average refractive index of the adhesion layer and the average refractive index of the second optical anisotropy layer is 0.08 or less. The phase difference film according to claim 8 or 9, wherein the difference between the average refractive index of the adhesion layer and the average refractive index of the third optical anisotropy layer is 0.08 or less.

11. A phase difference film according to claim 9, which satisfies all of the following requirements 1 to 4. Requirement 1: The difference between the average refractive index of the first optical anisotropy layer and the average refractive index of the layer in contact with the surface of the first optical anisotropy layer on the second optical anisotropy layer side is 0.10 or less. Requirement 2: At least one of the differences between the average refractive index of the second optical anisotropy layer and the average refractive index of the layer in contact with the surface of the second optical anisotropy layer on the first optical anisotropy layer side, and the difference between the average refractive index of the second optical anisotropy layer and the average refractive index of the layer in contact with the surface of the second optical anisotropy layer on the third optical anisotropy layer side, is 0.10 or less. Requirement 3: At least one of the differences between the average refractive index of the third optical anisotropy layer and the average refractive index of the layer in contact with the surface of the third optical anisotropy layer on the second optical anisotropy layer side, and the difference between the average refractive index of the third optical anisotropy layer and the average refractive index of the layer in contact with the surface of the third optical anisotropy layer on the fourth optical anisotropy layer side, is 0.10 or less. Requirement 4: The difference between the average refractive index of the fourth optical anisotropy layer and the average refractive index of the layer in contact with the surface of the fourth optical anisotropy layer on the third optical anisotropy layer side is 0.10 or less.

12. A circular polarizer comprising a polarizer and a phase difference film according to any one of claims 1 to 11.

13. A display device comprising a phase difference film according to any one of claims 1 to 11 or a circular polarizing plate according to claim 12.

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