Phase difference film, circular polarizer, display device

Abstract

The present invention provides: a phase difference film that has little change in color tone when applied to a display device as a circular polarizing plate by combining with a polarizer and the display device is observed diagonally at all azimuths; a circular polarizing plate; and a display device. A phase difference film according to the present invention includes an optically anisotropic layer X, an optically anisotropic layer Y, and an optically anisotropic layer Z in the stated order. The optically anisotropic layer X is an A-plate. The optically anisotropic layer Y is a layer obtained by immobilizing a first liquid crystal compound having twisted alignment along a spiral axis extending in the thickness direction. The optically anisotropic layer Z is a layer obtained by immobilizing a second liquid crystal compound having twisted alignment along a spiral axis extending in the thickness direction. Of the first liquid crystal compound and the second liquid crystal compound, one is a rod-shaped liquid crystal compound and the other is a discotic liquid crystal compound. The in-plane slow axis of the optically anisotropic layer X and the in-plane slow axis of the optically anisotropic layer Y on the optically anisotropic layer X-side surface thereof are parallel.

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 project] [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) comprising optical anisotropy layer X, optical anisotropy layer Y, and optical anisotropy layer Z in this order, The optically anisotropic layer X is plate A, The optically anisotropic layer Y is a layer in which a first liquid crystal compound is fixed in a torsion orientation along a helical axis extending in the thickness direction. The optically anisotropic layer Z is a layer in which a second liquid crystal compound is fixed in a torsion orientation along a helical axis extending in the thickness direction. One of the first and second liquid crystal compounds is a rod-shaped liquid crystal compound, and the other is a disc-shaped liquid crystal compound. A phase difference film in which the in-plane slow axis of optical anisotropy layer X and the in-plane slow axis of optical anisotropy layer Y on the surface facing optical anisotropy layer X are parallel. (2) The optically anisotropic layer X includes a positive A plate and a negative A plate, When a positive A plate and a negative A plate are arranged in this order from the surface opposite to the optical anisotropy layer Y side of the optical anisotropy layer X, the first liquid crystal compound is a rod-shaped liquid crystal compound, and the second liquid crystal compound is a disc-shaped liquid crystal compound. The phase difference film according to (1), wherein when a negative A plate and a positive A plate are arranged in this order from the surface of the optically anisotropic layer X opposite to the optically anisotropic layer Y side, the first liquid crystal compound is a disc-shaped liquid crystal compound and the second liquid crystal compound is a rod-shaped liquid crystal compound. (3) The in-plane retardation of plate A on the side of optical anisotropy layer X opposite to optical anisotropy layer Y is 20-90 nm at a wavelength of 550 nm. The phase difference film as described in (2), wherein the in-plane retardation of the A plate on the optical anisotropy layer Y side of the optical anisotropy layer X at a wavelength of 550 nm is 70 to 200 nm. (4) The phase difference film according to (2) or (3), wherein the twist angle of the first liquid crystal compound is within the range of 40 ± 20°. (5) A phase difference film according to any of (2) to (4), wherein the twist angle of the second liquid crystal compound is within the range of 40 ± 20°. (6) A phase difference film according to any of (2) to (5), wherein the product Δnd of the refractive index anisotropy Δn of the optical anisotropy layer Y at a wavelength of 550 nm and the thickness d of the optical anisotropy layer Y is 50 to 120 nm. (7) A phase difference film according to any of (2) to (6), wherein the product Δnd of the refractive index anisotropy Δn of the optical anisotropy layer Z at a wavelength of 550 nm and the thickness d of the optical anisotropy layer Z is 50 to 120 nm. (8) The optically anisotropic layer X is either a positive A plate or a negative A plate, When the optically anisotropic layer X is a positive A plate, the first liquid crystal compound is a disc-shaped liquid crystal compound, and the second liquid crystal compound is a rod-shaped liquid crystal compound. The phase difference film according to (1), wherein, when the optically anisotropic layer X is a negative A plate, the first liquid crystal compound is a rod-shaped liquid crystal compound and the second liquid crystal compound is a disc-shaped liquid crystal compound. (9) The phase difference film according to (8), wherein the in-plane retardation of the optical anisotropy layer X at a wavelength of 550 nm is 120 to 240 nm. (10) The phase difference film according to (8) or (9), wherein the torsion angle of the first liquid crystal compound is 80 ± 30°. (11) A phase difference film according to any of (8) to (10), wherein the torsion angle of the second liquid crystal compound is 175 ± 30°. (12) A phase difference film according to any of (8) to (11), wherein the product Δnd of the refractive index anisotropy Δn of the optical anisotropy layer Y at a wavelength of 550 nm and the thickness d of the optical anisotropy layer Y is 120 to 240 nm. (13) A phase difference film according to any of (8) to (12), wherein the product Δnd of the refractive index anisotropy Δn of the optical anisotropy layer Z at a wavelength of 550 nm and the thickness d of the optical anisotropy layer Z is 70 to 190 nm. (14) A circular polarizer comprising a polarizer and a phase difference film as described in any of (1) to (13). (15) A display device comprising a phase difference film as described in any of (1) to (13) or a circular polarizer as described in (14). [Effects of the Invention]

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

Brief Description of Drawings

[0009] [Figure 1] It is an example of a schematic cross-sectional view of a first embodiment of the retardation film of the present invention. [Figure 2] It is an example of a schematic cross-sectional view of a 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 first to fourth optically anisotropic layers 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 first to fourth optically anisotropic layers 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 a second embodiment of the retardation film of the present invention. [Figure 6] It is an example of a schematic cross-sectional view of a 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 first to fourth optically anisotropic layers 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 first to fourth optically anisotropic layers 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 a third embodiment of the retardation film of the present invention. [Figure 10] It is an example of a schematic cross-sectional view of a third embodiment of the circular polarizing plate of the present invention. [Figure 11]This figure shows the relationship between the absorption axis of the polarizer and the in-plane slow-phase axes of the first to third optical anisotropic layers in a third embodiment of the circular polarizer of the present invention. [Figure 12] This is a schematic diagram showing the relationship between the absorption axis of the polarizer, as observed from the direction of the white arrow in Figure 10, and the in-plane slow phase axis of the first to third optical anisotropic layers, respectively. [Figure 13] This is an example of a schematic cross-sectional view of a fourth embodiment of the phase difference film of the present invention. [Figure 14] This is an example of a schematic cross-sectional view of a fourth embodiment of the circular polarizing plate of the present invention. [Figure 15] This figure shows the relationship between the absorption axis of the polarizer and the in-plane slow-phase axes of the first to third optical anisotropic layers in the fourth embodiment of the circular polarizer of the present invention. [Figure 16] This is a schematic diagram showing the relationship between the absorption axis of the polarizer, as observed from the direction of the white arrow in Figure 14, and the angle between the in-plane slow phase axis of the first to third optical anisotropic layers. [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 average 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 indices nx, ny, and nz are measured using an Abbe refractometer (NAR-4T, manufactured by Atago Corporation) 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 Corporation) in combination with an interference filter. 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, "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°.

[0015] A key feature of the phase difference film of the present invention is that it uses a combination of predetermined optical anisotropic layers. The phase difference film of the present invention comprises an optically anisotropic layer X, an optically anisotropic layer Y, and an optically anisotropic layer Z in this order, wherein the optically anisotropic layer X is an A plate, the optically anisotropic layer Y is a layer in which a first liquid crystal compound is fixed in a twist orientation along a helical axis extending in the thickness direction, and the optically anisotropic layer Z is a layer in which a second liquid crystal compound is fixed in a twist orientation along a helical axis extending in the thickness direction, one of the first liquid crystal compound and the second liquid crystal compound is a rod-shaped liquid crystal compound and the other is a disc-shaped liquid crystal compound, and the in-plane slow axis of the optically anisotropic layer X and the in-plane slow axis of the optically anisotropic layer Y on the surface facing the optically anisotropic layer X are parallel. In the first embodiment of the phase difference film described later, the optical anisotropy layer X is composed of a first optical anisotropy layer 12A and a second optical anisotropy layer 14A, the optical anisotropy layer Y is composed of a third optical anisotropy layer 16A, and the optical anisotropy layer Z is composed of a fourth optical anisotropy layer 18A. Furthermore, in the second embodiment of the phase difference film, the optical anisotropy layer X is composed of the first optical anisotropy layer 12B and the second optical anisotropy layer 14B, the optical anisotropy layer Y is composed of the third optical anisotropy layer 16B, and the optical anisotropy layer Z is composed of the fourth optical anisotropy layer 18B. Furthermore, in the third embodiment of the phase difference film, the optical anisotropy layer X is formed by the first optical anisotropy layer 12C, the optical anisotropy layer Y is formed by the second optical anisotropy layer 14C, and the optical anisotropy layer Z is formed by the third optical anisotropy layer 16C. Furthermore, in the fourth embodiment of the phase difference film, the optical anisotropy layer X is formed by the first optical anisotropy layer 12D, the optical anisotropy layer Y is formed by the second optical anisotropy layer 14D, and the optical anisotropy layer Z is formed by the third optical anisotropy layer 16D.

[0016] <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 positive A 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 LC1, 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 layer in which disc-shaped liquid crystal compounds LC2, which are twisted and oriented along a helical axis extending in the thickness direction, are fixed. The in-plane slow axis of the first optical anisotropy layer 12A and the in-plane slow axis of the second optical anisotropy layer 14A are parallel. 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 are parallel. The in-plane slow axis on the surface of the third optical anisotropy layer 16A facing the fourth optical anisotropy layer 18A is parallel to the in-plane slow axis on the surface of the fourth optical anisotropy layer 18A facing the third optical anisotropy layer 16A. The following provides a detailed description of each layer.

[0017] (First optically anisotropic layer 12A) The first optically anisotropic layer 12A is a positive A plate. The in-plane retardation of the first optical anisotropy layer 12A at a wavelength of 550 nm is not particularly limited, but when the phase difference film and polarizer of the present invention are combined and applied to an image display device as a circular polarizer, and the image 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 20 to 90 nm is preferred, and 20 to 80 nm is more preferred. The retardation in the thickness direction of the first optical anisotropy layer 12A at a wavelength of 550 nm is not particularly limited, but 10 to 45 nm is preferred, and 10 to 40 nm is more preferred, in terms of achieving superior effects of the present invention.

[0018] The first optical anisotropy layer 12A 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.

[0019] The first optical anisotropic layer 12A 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°. As the rod-shaped liquid crystal compound, 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. 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.

[0020] The first optically anisotropic layer 12A is preferably a layer formed by fixing a rod-shaped liquid crystal compound having polymerizable groups by polymerization.

[0021] The thickness of the first optical anisotropy layer 12A 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 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.

[0022] (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 70 to 200 nm is preferred, and 80 to 190 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 -100 to -35 nm is preferred, and -95 to -40 nm is more preferred, in terms of achieving superior effects of the present invention.

[0023] 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.

[0024] 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°. 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. 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.

[0025] The second optically anisotropic layer 14A is preferably a layer formed by fixing a disc-shaped liquid crystal compound having polymerizable groups through polymerization.

[0026] The in-plane slow axis of the first optical anisotropy layer 12A and the in-plane slow axis of the second optical anisotropy layer 14A are parallel.

[0027] 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.

[0028] (Third optical anisotropy layer 16A) The third optically anisotropic layer 16A is a layer in which rod-shaped liquid crystal compounds LC1, which are twisted and oriented along a helical axis extending in the thickness direction, are fixed. 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 liquid crystal compound and a chiral agent described later.

[0029] The torsion angle of the rod-shaped liquid crystal compound (the torsion 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, in terms of achieving superior effects of the present invention, a range of 40±20° (20~60°) is preferred, and a range of 40±15° (25~55°) is more preferred. 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 more preferably in the range of 0 ± 10°.

[0030] 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, a value of 50 to 120 nm is preferred, and 55 to 115 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.

[0031] 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.

[0032] 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. 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.

[0033] 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.

[0034] 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.

[0035] (Fourth optical anisotropy layer 18A) The fourth optical anisotropic layer 18A is a layer in which a disc-shaped liquid crystal compound LC2, which is twisted and oriented along a helical axis extending in the thickness direction, is fixed. When forming the fourth optical anisotropy layer 18A described above, it is preferable to use at least a disc-shaped liquid crystal compound and a chiral agent described later.

[0036] 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 40±20° (20~60°) is preferred, and a range of 40±15° (25~55°) 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 from one main surface to the other main surface of the fourth optical anisotropy layer 18A twists around the thickness direction of the fourth optical anisotropy layer 18A as the axis. 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 layer. 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 is parallel to the thickness direction of the layer. However, strict parallelism is not required; it is preferable that the angle between the disc surface and the thickness direction of the second optical anisotropy layer 14A is in the range of 0 ± 20°, and preferably in the range of 0 ± 10°.

[0037] The in-plane slow axis on the surface of the third optical anisotropy layer 16A facing the fourth optical anisotropy layer 18A is parallel to the in-plane slow axis on the surface of the fourth optical anisotropy layer 18A facing the third optical anisotropy layer 16A.

[0038] The value of the product Δnd, which is the refractive index anisotropy Δn of the fourth optical anisotropy layer 18A at a wavelength of 550 nm and the thickness d of the fourth optical anisotropy layer 18A, is not particularly limited. However, a value of 50 to 120 nm is preferred, and 55 to 115 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.

[0039] The type of disc-shaped liquid crystal compound used to form the fourth optical anisotropy layer 18A 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.

[0040] The fourth optical anisotropic layer 18A 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.

[0041] 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.

[0042] (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.

[0043] (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.

[0044] 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.

[0045] 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.

[0046] (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.

[0047] 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. The alignment film may be peelable from the phase difference film together with the substrate, as described later.

[0048] (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.

[0049] 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 peelable from the phase difference film.

[0050] (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.

[0051] 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.

[0052] 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.

[0053] 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 and the fourth optical anisotropy layer 18A 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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 rod-shaped liquid crystal compounds are homogeneously oriented. When forming the second optical anisotropy layer 14A, the disc-shaped liquid crystal compounds are vertically oriented so that their optical axes (axes perpendicular to the disc surface) are aligned in the same direction. When forming the third optical anisotropy layer, the rod-shaped liquid crystal compounds are twisted. When forming the fourth optical anisotropy layer, the disc-shaped liquid crystal compounds are twisted.

[0058] 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.

[0059] 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.

[0060] <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).

[0061] 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.

[0062] 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 first optical anisotropy layer 12A to the fourth optical anisotropy layer 18A 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 first optical anisotropy layer 12A to the fourth optical anisotropy layer 18A 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 first optical anisotropy layer 12A to the fourth optical anisotropy layer 18A, 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 twist direction is determined by observing from the white arrow in Figure 2, based on the in-plane slow axis on the front side (opposite side from the polarizer 20) of the third optical anisotropy layer 16A and the fourth optical anisotropy layer 18A, determining whether it is a right-handed twist (clockwise) or a left-handed twist (counterclockwise).

[0063] 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 first optical anisotropy layer 12A is 75°. More specifically, the in-plane slow axis of the first optical anisotropy layer 12A is rotated 75° (75° counterclockwise) 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 first optical anisotropy layer 12A is at a position of 75°, the present invention is not limited to this embodiment, and it is preferable that it be in 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 first optical anisotropy layer 12A is within the range of 75±13°. As shown in Figure 3, within the first optical anisotropy layer 12A, the in-plane slow axis at the polarizer 20 side surface 121A of the first optical anisotropy layer 12A and the in-plane slow axis at the second optical anisotropy layer 14A side surface 122A of the first optical anisotropy layer 12A are parallel.

[0064] As shown in Figures 3-4, the in-plane slow axis of the first optical anisotropy layer 12A and the in-plane slow axis of the second optical anisotropy layer 14A are parallel.

[0065] Furthermore, 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 and the in-plane slow axis at the third optical anisotropy layer 16A side surface 142A of the second optical anisotropy layer 14A are parallel.

[0066] Furthermore, as shown in Figure 3, the in-plane slow axis at the surface 142A of the second optical anisotropy layer 14A on the side of the third optical anisotropy layer 16A is parallel to 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.

[0067] As described above, the third optical anisotropy layer 16A is a layer in which rod-shaped liquid crystal compounds, twisted and oriented along a helical axis extending in the thickness direction, are fixed. 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 aforementioned twist angle (40° 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 40°. More specifically, the torsion direction of the rod-shaped liquid crystal compound in the third optical anisotropy layer 16A is left-handed (counterclockwise), and the torsion angle is 40°. Therefore, the angle between the absorption axis of the polarizer 20 and the in-plane slow axis on the surface 162A of the third optical anisotropy layer 16A opposite to the second optical anisotropy layer 14A is 35°. 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 40°. However, 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 40 ± 20°. In other words, it is preferable that the angle between the in-plane slow phase 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 phase 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 40 ± 20°.

[0068] Furthermore, as shown in Figure 3, the in-plane slow axis at the surface 162A of the third optical anisotropy layer 16A on the fourth optical anisotropy layer 18A side and the in-plane slow axis at the surface 181A of the fourth optical anisotropy layer 18A on the third optical anisotropy layer 16A side are parallel.

[0069] As described above, the fourth optical anisotropy layer 18A 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 3-4, the in-plane slow axis at the surface 181A of the fourth optical anisotropy layer 18A on the side of the third optical anisotropy layer 16A and the in-plane slow axis at the surface 182A of the fourth optical anisotropy layer 18A opposite to the side of the third optical anisotropy layer 16A form the aforementioned twist angle (40° in Figure 3). In other words, the angle φa3 between the in-plane slow axis at the surface 181A of the fourth optical anisotropy layer 18A on the side of the third optical anisotropy layer 16A and the in-plane slow axis at the surface 182A opposite to the side of the third optical anisotropy layer 16A is 40°. More specifically, the torsion direction of the disc-shaped liquid crystal compound in the fourth optical anisotropy layer 18A is left-handed (counterclockwise), and the torsion angle is 40°. Therefore, the angle between the absorption axis of the polarizer 20 and the in-plane slow phase axis on the surface 162A of the fourth optical anisotropy layer 18A opposite to the third optical anisotropy layer 16A is 5°. In Figures 3-4, the torsion angle of the disc-shaped liquid crystal compound in the third optical anisotropy layer 16A is shown to be 40°, but the invention is not limited to this embodiment, and it is preferable that the torsion angle of the disc-shaped liquid crystal compound be within the range of 40 ± 20°. In other words, it is preferable that the angle between the in-plane slow axis on the surface 181A of the fourth optical anisotropy layer 18A on the side of the third optical anisotropy layer 16A and the in-plane slow axis on the surface 182A of the fourth optical anisotropy layer 18A on the opposite side of the third optical anisotropy layer 16A is within the range of 40 ± 20°.

[0070] 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 axes of the first optical anisotropy layer 12A and the second optical anisotropy layer 14A are rotated counterclockwise by 75° with respect to the absorption axis of the polarizer 20, the twist direction of the rod-shaped liquid crystal compound in the third optical anisotropy layer 16A is counterclockwise (left twist), and the twist direction of the disc-shaped liquid crystal compound in the fourth optical anisotropy layer 18A is counterclockwise (left twist). Figures 3-4 detail the configuration in which the torsion direction of the liquid crystal compound is counterclockwise, but a clockwise configuration is also possible as long as the predetermined angular relationship is satisfied. More specifically, when observing the circular polarizer 100A from the phase difference film 10A side, the in-plane slow axis of the first optical anisotropy layer 12A and the second optical anisotropy layer 14A is rotated 75° clockwise with respect to the absorption axis of the polarizer 20, the torsion direction of the rod-shaped liquid crystal compound in the third optical anisotropy layer 16A is clockwise (right-handed twist), and the torsion direction of the disc-shaped liquid crystal compound in the fourth optical anisotropy layer 18A is clockwise (right-handed twist).

[0071] 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 first optical anisotropy layer and 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 side of the fourth optical anisotropy layer, and that the twisting direction of the disc-shaped liquid crystal compound in the fourth optical anisotropy layer is counterclockwise with respect to the in-plane slow axis on the surface of the fourth optical anisotropy layer opposite to the side of the third optical anisotropy layer. 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 first optical anisotropy layer and 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 side of the fourth optical anisotropy layer, and that the twisting direction of the disc-shaped liquid crystal compound in the fourth optical anisotropy layer is clockwise with respect to the in-plane slow axis on the surface of the fourth optical anisotropy layer opposite to the side of the third optical anisotropy layer.

[0072] 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 known adhesive layers and bonding layers.

[0073] 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.

[0074] <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 negative A 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 LC1, twisted and oriented along a helical axis extending in the thickness direction, is fixed, and the fourth optical anisotropy layer 18B is a layer in which a rod-shaped liquid crystal compound LC2, twisted and oriented along a helical axis extending in the thickness direction, is fixed. The in-plane slow axis of the first optical anisotropy layer 12B and the in-plane slow axis of the second optical anisotropy layer 14B are parallel. 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 are parallel. The in-plane slow axis on the surface of the third optical anisotropy layer 16B facing the fourth optical anisotropy layer 18B is parallel to the in-plane slow axis on the surface of the fourth optical anisotropy layer 18B facing the third optical anisotropy layer 16B. The following provides a detailed description of each layer.

[0075] (First optical anisotropy layer 12B) The first optically anisotropic layer 12B is a negative A plate. The in-plane retardation of the first optical anisotropy layer 12B at a wavelength of 550 nm is not particularly limited, but 20 to 90 nm is preferred, and 20 to 80 nm is more preferred, in terms of achieving superior effects of the present invention. The retardation in the thickness direction of the first optical anisotropy layer 12B at a wavelength of 550 nm is not particularly limited, but -45 to -10 nm is preferred, and -40 to -10 nm is more preferred, in terms of superior effects of the present invention.

[0076] The first optical anisotropy layer 12B 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.

[0077] The first optical anisotropy layer 12B 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°. The type of disc-shaped liquid crystal compound used to form the first optical anisotropy layer 12B 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.

[0078] The first optically anisotropic layer 12B is preferably a layer formed by fixing a disc-shaped liquid crystal compound having polymerizable groups by polymerization.

[0079] The in-plane slow axis of the first optical anisotropy layer 12B and the in-plane slow axis of the second optical anisotropy layer 14B are parallel.

[0080] 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 these measurements.

[0081] (Second optical anisotropy layer 14B) 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 70 to 200 nm is preferred, and 80 to 190 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 35 to 100 nm is preferred, and 40 to 95 nm is more preferred, in terms of achieving superior effects of the present invention.

[0082] 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.

[0083] 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. The type of rod-shaped liquid crystal compound used to form the second optical anisotropy layer 14B is not particularly limited, and known compounds can be used. The rod-shaped liquid crystal compound may have polymerizable groups. The types of polymerizable groups that the rod-shaped liquid crystal compound may possess are as described above.

[0084] The second optically anisotropic layer 14B is preferably a layer formed by fixing a rod-shaped liquid crystal compound having polymerizable groups by polymerization.

[0085] 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.

[0086] (Third optical anisotropy layer 16B) The third optically anisotropic layer 16B is a layer in which a disc-shaped liquid crystal compound LC1, which is twisted and oriented along a helical axis extending in the thickness direction, is 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.

[0087] 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 40±20° (20~60°) is preferred, and a range of 40±15° (35~55°) 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°.

[0088] The in-plane slow axis of the second optical anisotropy layer 14B is parallel to the in-plane slow axis of the third optical anisotropy layer 16B on the surface facing the second optical anisotropy layer 14B.

[0089] 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, but 50 to 120 nm is preferred, and 55 to 115 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] (Fourth optical anisotropy layer 18B) The fourth optical anisotropic layer 18B is a layer in which rod-shaped liquid crystal compounds LC2, which are twisted and oriented along a helical axis extending in the thickness direction, are fixed. The fourth optical anisotropy layer 18B is preferably a layer formed by fixing a chiral nematic phase having a so-called helical structure. When forming the fourth optical anisotropy layer 18B, it is preferable to use at least a liquid crystal compound and a chiral agent.

[0094] The torsion angle of the rod-shaped liquid crystal compound (the torsion 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, in terms of achieving superior effects of the present invention, a range of 40±20° (20~60°) is preferred, and a range of 40±15° (35~55°) is more preferred. 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 fourth optical anisotropy layer 18B, with the thickness direction of the fourth optical anisotropy layer 18B 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 fourth optical anisotropy layer 18B. In the torsional orientation, the long axis of the rod-shaped liquid crystal compound is positioned parallel to the main surface of the fourth optical anisotropy layer 18B. 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 fourth optical anisotropy layer 18B is preferably in the range of 0 ± 20°, and more preferably in the range of 0 ± 10°.

[0095] The value of the product Δnd, which is the refractive index anisotropy Δn of the fourth optical anisotropy layer 18B at a wavelength of 550 nm and the thickness d of the fourth optical anisotropy layer 18B, is not particularly limited, but 50 to 120 nm is preferred, and 55 to 115 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.

[0096] The in-plane slow axis on the surface of the third optical anisotropy layer 16B facing the fourth optical anisotropy layer 18B is parallel to the in-plane slow axis on the surface of the fourth optical anisotropy layer 18B facing the third optical anisotropy layer 16B.

[0097] The type of rod-shaped liquid crystal compound used to form the fourth optical anisotropy layer 18B is not particularly limited, and known compounds can be used. 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.

[0098] The fourth optical anisotropic layer 18B 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.

[0099] The thickness of the fourth optical anisotropy layer 18B 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 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.

[0100] (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.

[0101] 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.

[0102] <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 image 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.

[0103] 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 first optical anisotropy layer 12B to the fourth optical anisotropy layer 18B 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 first optical anisotropy layer 12B to the fourth optical anisotropy layer 18B represent the in-plane slow axis in each layer. Figure 8 shows the relationship between the angle between the absorption axis of polarizer 20 (dashed line) and the in-plane slow phase axes (solid lines) of the first optical anisotropy layer 12B to the fourth optical anisotropy layer 18B, 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 by observing from the white arrow in Figure 6, based on the in-plane slow axis on the front side (opposite side from the polarizer 20) of the third optical anisotropy layer 16B and the fourth optical anisotropy layer 18B, determining whether it is a right-handed twist (clockwise) or a left-handed twist (counterclockwise).

[0104] 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 first optical anisotropy layer 12B is 15°. More specifically, the in-plane slow axis of the first optical anisotropy layer 12B is rotated by -15° (15° clockwise) 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 first optical anisotropy layer 12B is at a -15° position, the present invention is not limited to this embodiment, and it is preferable that the angle is in 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 first optical anisotropy layer 12B is within the range of 15±13°. As shown in Figure 7, within the first optical anisotropy layer 12B, the in-plane slow axis at the polarizer 20 side surface 121B of the first optical anisotropy layer 12B is parallel to the in-plane slow axis at the second optical anisotropy layer 14B side surface 122B of the first optical anisotropy layer 12B.

[0105] As shown in Figures 7-8, the in-plane slow axis of the first optical anisotropy layer 12B and the in-plane slow axis of the second optical anisotropy layer 14B are parallel.

[0106] Furthermore, 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.

[0107] Furthermore, as shown in Figure 7, the in-plane slow axis at the surface 142B of the second optical anisotropy layer 14B on the side of the third optical anisotropy layer 16B is parallel to the in-plane slow axis at the surface 161B of the third optical anisotropy layer 16B on the side of the second optical anisotropy layer 14B.

[0108] 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 at 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 at the surface 162B of the third optical anisotropy layer 16B opposite to the side of the second optical anisotropy layer 14B form the aforementioned twist angle (40° in Figure 7). In other words, the angle φb2 between the in-plane slow axis at 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 at the surface 162B opposite to the side of the second optical anisotropy layer 14B is 40°. More specifically, the torsion direction of the disc-shaped liquid crystal compound in the third optical anisotropy layer 16B is left-handed (counterclockwise), and the torsion angle is 40°. 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 55°. 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 40°. However, the invention is not limited to this embodiment, and it is preferable that the torsion angle of the disc-shaped liquid crystal compound be within the range of 40 ± 20°. In other words, it is preferable that 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 within the range of 40 ± 20°.

[0109] Furthermore, as shown in Figure 7, the in-plane slow axis at the surface 162B of the third optical anisotropy layer 16B on the fourth optical anisotropy layer 18B side and the in-plane slow axis at the surface 181B of the fourth optical anisotropy layer 18B on the third optical anisotropy layer 16B side are parallel.

[0110] As described above, the fourth optical anisotropy layer 18B 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 7-8, the in-plane slow axis on the polarizer 20 side surface 181B of the fourth optical anisotropy layer 18B and the in-plane slow axis on the opposite side of the polarizer 20 surface 182B of the fourth optical anisotropy layer 18B form the aforementioned twist angle (40° in Figure 7). In other words, the angle φb3 between the in-plane slow axis on the polarizer 20 side surface 181B of the fourth optical anisotropy layer 18B and the in-plane slow axis on the opposite side of the polarizer 20 surface 182B of the fourth optical anisotropy layer 18B is 40°. More specifically, the torsion direction of the disc-shaped liquid crystal compound in the fourth optical anisotropy layer 18B is left-handed (counterclockwise), and the torsion angle is 40°. Therefore, the angle between the absorption axis of the polarizer 20 and the in-plane slow phase axis on the surface 182B of the fourth optical anisotropy layer 18B opposite to the third optical anisotropy layer 16B side is 95°. In Figures 7-8, the torsion angle of the disc-shaped liquid crystal compound in the fourth optical anisotropy layer 18B is shown to be 40°. However, the invention is not limited to this embodiment, and the torsion angle of the disc-shaped liquid crystal compound can be in the range of 40±20°. In other words, it is preferable that the angle between the in-plane slow axis on the surface 181B of the fourth optical anisotropy layer 18B on the side of the third optical anisotropy layer 16B and the in-plane slow axis on the surface 182B of the fourth optical anisotropy layer 18B opposite to the side of the third optical anisotropy layer 16B is within the range of 40±20°.

[0111] 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 phase axes of the first optical anisotropy layer 12B and the second optical anisotropy layer 14B are rotated 15° clockwise with respect to the absorption axis of the polarizer 20, the twist direction of the disc-shaped liquid crystal compound in the third optical anisotropy layer 16B is counterclockwise (left twist), and the twist direction of the rod-shaped liquid crystal compound in the fourth optical anisotropy layer 18B is counterclockwise (left twist). Figures 7-8 detail the configuration in which the torsion direction of the liquid crystal compound is counterclockwise, but a clockwise configuration is also possible as long as the predetermined angular relationship is satisfied. More specifically, when observing the circular polarizer 100B from the phase difference film 10B side, the in-plane slow axis of the first optical anisotropy layer 12B and the second optical anisotropy layer 14B is rotated 15° counterclockwise with respect to the absorption axis of the polarizer 20, the torsion direction of the disc-shaped liquid crystal compound in the third optical anisotropy layer 16B is clockwise (right-handed twist), and the torsion direction of the rod-shaped liquid crystal compound in the fourth optical anisotropy layer 18B is clockwise (right-handed twist).

[0112] 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 first optical anisotropy layer and 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 side of the fourth optical anisotropy layer, and that the twisting direction of the liquid crystal compound in the fourth optical anisotropy layer is counterclockwise with respect to the in-plane slow axis on the surface of the fourth optical anisotropy layer opposite to the side of the third optical anisotropy layer. Furthermore, in a circular polarizer including a 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 first optical anisotropy layer and 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 side of the fourth optical anisotropy layer, and that the twisting direction of the liquid crystal compound in the fourth optical anisotropy layer is clockwise with respect to the in-plane slow axis on the surface of the fourth optical anisotropy layer opposite to the side of the third optical anisotropy layer.

[0113] 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 known adhesive layers and bonding layers.

[0114] 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.

[0115] <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, and a third optical anisotropy layer 16C in that order. The first optically anisotropic layer 12C is a positive A plate, the second optically anisotropic layer 14C is a layer in which a disc-shaped liquid crystal compound LC1 is fixed in a twist orientation along a helical axis extending in the thickness direction, and the third optically anisotropic layer 16C is a layer in which a rod-shaped liquid crystal compound LC2 is fixed in a twist orientation along a helical axis extending in the thickness direction. The in-plane slow axis of the first optical anisotropy layer 12C and the in-plane slow axis of the second optical anisotropy layer 14C on the surface facing the first optical anisotropy layer 12C are parallel. The in-plane slow axis on the surface of the second optical anisotropy layer 14C facing the third optical anisotropy layer 16C is parallel to the in-plane slow axis on the surface of the third optical anisotropy layer 16C facing the second optical anisotropy layer 14C. The following provides a detailed description of each layer.

[0116] (First optical anisotropy layer 12C) The first optically anisotropic layer 12C is a positive A plate. The in-plane retardation of the first optical anisotropy layer 12C 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 superior effects of the present invention. The retardation in the thickness direction of the first optical anisotropy layer 12C 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.

[0117] The first optical anisotropy layer 12C 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.

[0118] The first optical anisotropy layer 12C 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. The type of rod-shaped liquid crystal compound used to form the first optical anisotropy layer 12C is not particularly limited, and known compounds can be used. 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.

[0119] The first optically anisotropic layer 12C is preferably a layer formed by fixing a rod-shaped liquid crystal compound having polymerizable groups by polymerization.

[0120] The thickness of the first optical anisotropy layer 12C 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 12C refers to the average thickness of the first optical anisotropy layer 12C. The above average thickness is obtained by measuring the thickness of any five or more points on the first optical anisotropy layer 12C and taking the arithmetic mean of them.

[0121] (Second optical anisotropy layer 14C) The second optically anisotropic layer 14C is a layer in which disc-shaped liquid crystal compounds LC1, which are twisted and oriented along a helical axis extending in the thickness direction, are fixed. When forming the second optical anisotropy layer 14C described above, it is preferable to use at least a disc-shaped liquid crystal compound and a chiral agent.

[0122] 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 second optical anisotropy layer 14C, from one main surface to the other main surface of the second optical anisotropy layer 14C. Consequently, the orientation direction of the disc-shaped liquid crystal compound (in-plane slow phase axis direction) differs depending on its position in the thickness direction of the second optical anisotropy layer 14C. 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 second optical anisotropy layer 14C are parallel. However, strict parallelism is not required; the angle between the disc surface and the thickness direction of the second optical anisotropy layer 14C is preferably in the range of 0 ± 20°, and preferably in the range of 0 ± 10°.

[0123] The in-plane slow axis of the first optical anisotropy layer 12C is parallel to the in-plane slow axis of the second optical anisotropy layer 14C on the surface facing the first optical anisotropy layer 12C.

[0124] The value of the product Δnd, which is the refractive index anisotropy Δn of the second optical anisotropy layer 14C at a wavelength of 550 nm and the thickness d of the second optical anisotropy layer 14C, 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.

[0125] The type of disc-shaped liquid crystal compound used to form the second optical anisotropy layer 14C 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.

[0126] The second optically anisotropic layer 14C 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.

[0127] The thickness of the second optical anisotropy layer 14C 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 14C refers to the average thickness of the second optical anisotropy layer 14C. The above average thickness is obtained by measuring the thickness of any five or more points on the second optical anisotropy layer 14C and taking the arithmetic mean of these measurements.

[0128] (Third optical anisotropy layer 16C) The third optically anisotropic layer 16C is a layer in which rod-shaped liquid crystal compounds LC2, which are twisted and oriented along a helical axis extending in the thickness direction, are fixed. The third optical anisotropy layer 16C is preferably a layer formed by fixing a chiral nematic phase having a so-called helical structure. When forming the third optical anisotropy layer 16C, it is preferable to use at least a liquid crystal compound and a chiral agent.

[0129] The torsion angle of the rod-shaped liquid crystal compound (the torsion 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, in terms of achieving superior effects of the present invention, a range of 175±30° (145~205°) is preferred, and a range of 175±20° (155~195°) is more preferred. 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 16C, with the thickness direction of the third optical anisotropy layer 16C 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 16C. 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 16C. 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 16C is preferably in the range of 0 ± 20°, and preferably in the range of 0 ± 10°.

[0130] The value of the product Δnd, which is the refractive index anisotropy Δn of the third optical anisotropy layer 16C at a wavelength of 550 nm and the thickness d of the third optical anisotropy layer 16C, is not particularly limited. However, a value of 70 to 190 nm is preferred, and 80 to 180 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.

[0131] In this embodiment, the in-plane slow axis on the surface of the second optical anisotropy layer 14C facing the third optical anisotropy layer 16C is parallel to the in-plane slow axis on the surface of the third optical anisotropy layer 16C facing the second optical anisotropy layer 14C. In the embodiment shown in Figure 9, the in-plane slow axis on the surface of the second optical anisotropy layer 14C facing the third optical anisotropy layer 16C is parallel to the in-plane slow axis on the surface of the third optical anisotropy layer 16C facing the second optical anisotropy layer 14C. However, this embodiment is not limited to the above embodiment, and the in-plane slow axis on the surface of the second optical anisotropy layer 14C facing the third optical anisotropy layer 16C is not necessarily parallel to the in-plane slow axis on the surface of the third optical anisotropy layer 16C facing the second optical anisotropy layer 14C.

[0132] The type of rod-shaped liquid crystal compound used to form the third optical anisotropy layer 16C is not particularly limited, and known compounds can be used. 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.

[0133] The third optically anisotropic layer 16C is preferably a layer formed by fixing rod-shaped liquid crystal compounds having polymerizable groups by polymerization. More specifically, it is more preferable that the layer is formed by fixing rod-shaped liquid crystal compounds having twistedly oriented polymerizable groups by polymerization.

[0134] The thickness of the third optical anisotropy layer 16C 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 16C refers to the average thickness of the third optical anisotropy layer 16C. This average thickness is obtained by measuring the thickness of any five or more points on the third optical anisotropy layer 16C and taking their arithmetic mean.

[0135] (Other components) The phase difference film 10C may include other components besides the first optical anisotropy layer 12C to the third optical anisotropy layer 16C described above. Other components include those described in the first embodiment of the phase difference film mentioned above.

[0136] The method for manufacturing the first optical anisotropy layer 12C to the third optical anisotropy layer 16C 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.

[0137] <Third embodiment of a circular polarizing plate> A third 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.

[0138] Figure 10 shows a schematic cross-sectional view of one embodiment of the circular polarizer 100C. Figure 11 shows the relationship between the absorption axis of the polarizer 20 and the in-plane slow axis of the first optical anisotropy layer 12C to the third optical anisotropy layer 16C in the circular polarizer 100C shown in Figure 10. In Figure 11, the arrow in the polarizer 20 represents the absorption axis, and the arrows in the first optical anisotropy layer 12C to the third optical anisotropy layer 16C represent the in-plane slow axis in each layer. Figure 12 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 first optical anisotropy layer 12C to the third optical anisotropy layer 16C, as observed from the white arrow in Figure 10. 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 10. The torsional direction is determined by whether it is a right-handed twist (clockwise) or left-handed twist (counterclockwise) based on the in-plane slow axis on the front side (opposite side from the polarizer 20) of the second optical anisotropy layer 14C and the third optical anisotropy layer 16C when observed from the white arrow in Figure 10.

[0139] As shown in Figure 10, the circular polarizer 100C includes a polarizer 20, a first optical anisotropy layer 12C, a second optical anisotropy layer 14C, and a third optical anisotropy layer 16C in that order. As shown in Figures 11-12, the angle φc1 between the absorption axis of the polarizer 20 and the in-plane slow axis of the first optical anisotropy layer 12C is 15°. More specifically, the in-plane slow axis of the first optical anisotropy layer 12C is rotated by -15° (15° clockwise) with respect to the absorption axis of the polarizer 20. Although Figures 11-12 show an embodiment where the in-plane slow axis of the first optical anisotropy layer 12C is at a -15° position, the present invention is not limited to this embodiment, and it is preferable that the angle is in 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 first optical anisotropy layer 12C is within the range of 15±13°. As shown in Figure 11, within the first optical anisotropy layer 12C, the in-plane slow axis at the polarizer 20 side surface 121C of the first optical anisotropy layer 12C is parallel to the in-plane slow axis at the second optical anisotropy layer 14C side surface 122C of the first optical anisotropy layer 12C.

[0140] As shown in Figure 11, the in-plane slow axis at the surface 122C of the first optical anisotropy layer 12C on the side of the second optical anisotropy layer 14C is parallel to the in-plane slow axis at the surface 141C of the second optical anisotropy layer 14C on the side of the first optical anisotropy layer 12C.

[0141] As described above, the second optical anisotropy layer 14C 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 11-12, the in-plane slow axis at the surface 141C of the second optical anisotropy layer 14C on the side of the first optical anisotropy layer 12C and the in-plane slow axis at the surface 142C of the second optical anisotropy layer 14C opposite to the side of the first optical anisotropy layer 12C form the aforementioned twist angle (80° in Figure 11). In other words, the angle φc2 between the in-plane slow axis at the surface 141C of the second optical anisotropy layer 14C on the side of the first optical anisotropy layer 12C and the in-plane slow axis at the surface 142C of the second optical anisotropy layer 14C opposite to the side of the first optical anisotropy layer 12C is 80°. More specifically, the torsion direction of the disc-shaped liquid crystal compound in the second optical anisotropy layer 14C is left-handed (counterclockwise), 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 142C of the second optical anisotropy layer 14C opposite to the polarizer 20 side is 95°. In Figures 11-12, the torsion angle of the disc-shaped liquid crystal compound in the second optical anisotropy layer 14C is shown to be 80°. However, the model is not limited to this model, and it is preferable that the torsion angle of the disc-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 141C of the second optical anisotropy layer 14C on the side of the first optical anisotropy layer 12C and the in-plane slow axis on the surface 142C of the second optical anisotropy layer 14C opposite to the side of the first optical anisotropy layer 12C is within the range of 80±30°.

[0142] Furthermore, as shown in Figure 11, the in-plane slow axis at the surface 142C of the second optical anisotropy layer 14C on the side of the third optical anisotropy layer 16C is parallel to the in-plane slow axis at the surface 161C of the third optical anisotropy layer 16C on the side of the second optical anisotropy layer 14C.

[0143] As described above, the third optical anisotropy layer 16C 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 11-12, the in-plane slow axis at the surface 161C of the third optical anisotropy layer 16C on the side of the second optical anisotropy layer 14C and the in-plane slow axis at the surface 162C of the third optical anisotropy layer 16C opposite to the side of the second optical anisotropy layer 14C form the twist angle described above (175° in Figure 11). In other words, the angle φc3 between the in-plane slow axis at the surface 161C of the third optical anisotropy layer 16C on the side of the second optical anisotropy layer 14C and the in-plane slow axis at the surface 162C opposite to the side of the second optical anisotropy layer 14C is 175°. More specifically, the torsion direction of the rod-shaped liquid crystal compound in the third optical anisotropy layer 16C is left-handed (counterclockwise), and the torsion angle is 175°. Therefore, the angle between the absorption axis of the polarizer 20 and the in-plane slow phase axis on the surface 162C of the third optical anisotropy layer 16C opposite to the second optical anisotropy layer 14C is 270°. In Figures 11-12, the twist angle of the rod-shaped liquid crystal compound in the third optical anisotropy layer 16C is shown to be 175°. However, the model is not limited to this model, and it is preferable that the twist angle of the rod-shaped liquid crystal compound be within the range of 175±30°. In other words, it is preferable that the angle between the in-plane slow axis on the surface 161C of the third optical anisotropy layer 16C on the side of the second optical anisotropy layer 14C and the in-plane slow axis on the surface 162C of the third optical anisotropy layer 16C opposite to the side of the second optical anisotropy layer 14C is within the range of 175±30°.

[0144] As described above, in the embodiments shown in Figures 11-12, when the circular polarizer 100C is observed from the phase difference film 10C side, the in-plane slow phase axis of the first optical anisotropy layer 12C is rotated 15° clockwise with respect to the absorption axis of the polarizer 20, the twist direction of the disc-shaped liquid crystal compound in the second optical anisotropy layer 14C is counterclockwise (left twist), and the twist direction of the rod-shaped liquid crystal compound in the third optical anisotropy layer 16C is counterclockwise (left twist). Figures 11-12 detail the configuration in which the torsion direction of the liquid crystal compound is counterclockwise, but a clockwise configuration is also possible as long as the predetermined angular relationship is satisfied. More specifically, when the circular polarizer 100C is observed from the phase difference film 10C side, the in-plane slow axis of the first optical anisotropy layer 12C is rotated 15° counterclockwise with respect to the absorption axis of the polarizer 20, the torsion direction of the disc-shaped liquid crystal compound in the second optical anisotropy layer 14C is clockwise (right-handed twist), and the torsion direction of the rod-shaped liquid crystal compound in the third optical anisotropy layer 16C is clockwise (right-handed twist).

[0145] In other words, in a circular polarizer including a third 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 first optical anisotropy layer is rotated 15° clockwise with respect to the absorption axis of the polarizer, it is preferable that the twisting direction of the liquid crystal compound in the second optical anisotropy layer is counterclockwise with respect to the in-plane slow axis on the surface of the second optical anisotropy layer on the side of the third optical anisotropy layer, and 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 opposite to the side of the second optical anisotropy layer. Furthermore, in a circular polarizer including a third 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 first optical anisotropy layer is rotated 15° counterclockwise with respect to the absorption axis of the polarizer, it is preferable that the twisting direction of the liquid crystal compound in the second optical anisotropy layer is clockwise with respect to the in-plane slow axis on the surface of the second optical anisotropy layer on the side of the third optical anisotropy layer, and 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 opposite to the side of the second optical anisotropy layer.

[0146] 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 known adhesive layers and bonding layers.

[0147] 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.

[0148] <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 13 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, and a third optical anisotropy layer 16D in that order. The first optical anisotropy layer 12D is a negative A plate, the second optical anisotropy layer 14D is a layer in which rod-shaped liquid crystal compounds LC1 are fixed in a twist orientation along a helical axis extending in the thickness direction, and the third optical anisotropy layer 16D is a layer in which disc-shaped liquid crystal compounds LC2 are fixed in a twist orientation along a helical axis extending in the thickness direction. The in-plane slow axis of the first optical anisotropy layer 12D and the in-plane slow axis of the second optical anisotropy layer 14D on the surface facing the first optical anisotropy layer 12D are parallel. The in-plane slow axis on the surface of the second optical anisotropy layer 14D facing the third optical anisotropy layer 16D is parallel to the in-plane slow axis on the surface of the third optical anisotropy layer 16D facing the second optical anisotropy layer 14D. The following provides a detailed description of each layer.

[0149] (First optical anisotropy layer 12D) The first optically anisotropic layer 12D is a negative A plate. The in-plane retardation of the first optical anisotropy layer 12D 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 superior effects of the present invention. The retardation in the thickness direction of the first optical anisotropy layer 12D 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.

[0150] The first optical anisotropy layer 12D 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.

[0151] The first optical anisotropy layer 12D 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. A layer formed by fixing a vertically oriented disc-shaped liquid crystal compound is preferred in that it exhibits superior effects of the present invention. 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°. The type of disc-shaped liquid crystal compound used to form the first optical anisotropy layer 12D 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.

[0152] The first optically anisotropic layer 12D is preferably a layer formed by fixing a disc-shaped liquid crystal compound having polymerizable groups through polymerization.

[0153] The in-plane slow axis of the first optical anisotropy layer 12D and the in-plane slow axis of the second optical anisotropy layer 14D on the surface facing the first optical anisotropy layer 12D are parallel.

[0154] The thickness of the first optical anisotropy layer 12D 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 12D refers to the average thickness of the first optical anisotropy layer 12D. The above average thickness is obtained by measuring the thickness of any five or more points on the first optical anisotropy layer 12D and taking their arithmetic mean.

[0155] (Second optical anisotropy layer 14D) The second optically anisotropic layer 14D is a layer in which rod-shaped liquid crystal compounds LC1, which are twisted and oriented along a helical axis extending in the thickness direction, are fixed. The second optical anisotropic layer 14D is preferably a layer formed by fixing a chiral nematic phase having a so-called helical structure. When forming the second optical anisotropic layer 14D, it is preferable to use at least a liquid crystal compound and a chiral agent.

[0156] 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 second optical anisotropy layer 14D, with the thickness direction of the second optical anisotropy layer 14D as the axis. Consequently, the orientation direction of the rod-shaped liquid crystal compound (in-plane slow phase axis direction) differs depending on its position in the thickness direction of the second optical anisotropy layer 14D. In the torsional orientation, the long axis of the rod-shaped liquid crystal compound is positioned parallel to the main surface of the second optical anisotropy layer 14D. 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 second optical anisotropy layer 14D is preferably in the range of 0 ± 20°, and preferably in the range of 0 ± 10°.

[0157] The value of the product Δnd, which is the refractive index anisotropy Δn of the second optical anisotropy layer 14D at a wavelength of 550 nm and the thickness d of the second optical anisotropy layer 14D, 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.

[0158] The in-plane slow axis on the surface of the first optical anisotropy layer 12D facing the second optical anisotropy layer 14D is parallel to the in-plane slow axis on the surface of the second optical anisotropy layer 14D facing the first optical anisotropy layer 12D.

[0159] The type of rod-shaped liquid crystal compound used to form the second optical anisotropy layer 14D is not particularly limited, and known compounds can be used. 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.

[0160] The second optically anisotropic layer 14D is preferably a layer formed by fixing rod-shaped liquid crystal compounds having polymerizable groups by polymerization. More specifically, it is more preferable that the layer is formed by fixing rod-shaped liquid crystal compounds having twistedly oriented polymerizable groups by polymerization.

[0161] The thickness of the second optical anisotropy layer 14D 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 14D refers to the average thickness of the second optical anisotropy layer 14D. The above average thickness is obtained by measuring the thickness of any five or more points on the second optical anisotropy layer 14D and taking the arithmetic mean of these measurements.

[0162] (Third optical anisotropy layer 16D) The third optically anisotropic layer 16D is a layer in which disc-shaped liquid crystal compounds LC2, which are twisted and oriented along a helical axis extending in the thickness direction, are fixed. When forming the third optical anisotropy layer 16D described above, it is preferable to use at least a disc-shaped liquid crystal compound and a chiral agent.

[0163] 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 175±30° (145~205°) is preferred, and a range of 175±20° (155~195°) is more preferred, as this provides superior effects for 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 16D, from one main surface to the other main surface of the third optical anisotropy layer 16D. Consequently, the orientation direction of the disc-shaped liquid crystal compound (in-plane slow phase axis direction) differs depending on its position in the thickness direction of the third optical anisotropy layer 16D. 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 16D are parallel. However, strict parallelism is not required; the angle between the disc surface and the thickness direction of the third optical anisotropy layer 16D is preferably in the range of 0 ± 20°, and preferably in the range of 0 ± 10°.

[0164] In this embodiment, the in-plane slow axis on the surface of the second optical anisotropy layer 14D facing the third optical anisotropy layer 16D is parallel to the in-plane slow axis on the surface of the third optical anisotropy layer 16D facing the second optical anisotropy layer 14D. In the embodiment shown in Figure 13, the in-plane slow axis on the surface of the second optical anisotropy layer 14D facing the third optical anisotropy layer 16D is parallel to the in-plane slow axis on the surface of the third optical anisotropy layer 16D facing the second optical anisotropy layer 14D. However, this embodiment is not limited to the above embodiment, and the in-plane slow axis on the surface of the second optical anisotropy layer 14D facing the third optical anisotropy layer 16D is not necessarily parallel to the in-plane slow axis on the surface of the third optical anisotropy layer 16D facing the second optical anisotropy layer 14D.

[0165] The value of the product Δnd, which is the refractive index anisotropy Δn of the third optical anisotropy layer 16D at a wavelength of 550 nm and the thickness d of the third optical anisotropy layer 16D, is not particularly limited. However, a value of 70 to 190 nm is preferred, and 80 to 180 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.

[0166] The type of disc-shaped liquid crystal compound used to form the third optical anisotropy layer 16D 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.

[0167] The third optically anisotropic layer 16D 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.

[0168] The thickness of the third optical anisotropy layer 16D 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 16D refers to the average thickness of the third optical anisotropy layer 16D. This average thickness is obtained by measuring the thickness of any five or more points on the third optical anisotropy layer 16D and taking their arithmetic mean.

[0169] (Other components) The phase difference film 10D may include other components besides the first optical anisotropy layer 12D to the third optical anisotropy layer 16D described above. Other components include those described in the first embodiment of the phase difference film mentioned above.

[0170] The method for manufacturing the first optical anisotropy layer 12D to the third optical anisotropy layer 16D 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.

[0171] <Fourth embodiment of a circular polarizing plate> A third 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 image 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.

[0172] Figure 14 shows a schematic cross-sectional view of one embodiment of the circular polarizer 100D. Figure 15 shows the relationship between the absorption axis of the polarizer 20 and the in-plane slow axis of the first optical anisotropy layer 12D to the third optical anisotropy layer 16D in the circular polarizer 100D shown in Figure 14. In Figure 15, the arrow in the polarizer 20 represents the absorption axis, and the arrows in the first optical anisotropy layer 12D to the third optical anisotropy layer 16D represent the in-plane slow axis in each layer. Figure 16 also 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 first optical anisotropy layer 12D to the third optical anisotropy layer 16D, as observed from the white arrow in Figure 14. 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 14. The twist direction is determined by observing from the white arrow in Figure 14, based on the in-plane slow axis on the front side (opposite side from the polarizer 20) of the second optical anisotropy layer 14D and the third optical anisotropy layer 16D, determining whether it is a right-handed twist (clockwise) or a left-handed twist (counterclockwise).

[0173] As shown in Figure 14, the circular polarizer 100D includes a polarizer 20, a first optical anisotropy layer 12D, a second optical anisotropy layer 14D, and a third optical anisotropy layer 16D in that order. As shown in Figures 15-16, the angle φd1 between the absorption axis of the polarizer 20 and the in-plane slow axis of the first optical anisotropy layer 12D is 75°. More specifically, the in-plane slow axis of the first optical anisotropy layer 12D is rotated 75° (75° counterclockwise) with respect to the absorption axis of the polarizer 20. In Figures 14-16, the in-plane slow axis of the first optical anisotropy layer 12D is shown at a position of 75°, but the present invention is not limited to this embodiment, and it is preferable that it be in 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 first optical anisotropy layer 12D is within the range of 75±13°. As shown in Figure 15, within the first optical anisotropy layer 12D, the in-plane slow axis at the polarizer 20 side surface 121D of the first optical anisotropy layer 12D is parallel to the in-plane slow axis at the second optical anisotropy layer 14D side surface 122D of the first optical anisotropy layer 12D.

[0174] As shown in Figure 15, the in-plane slow axis at the surface 122D of the first optical anisotropy layer 12D on the side of the second optical anisotropy layer 14D is parallel to the in-plane slow axis at the surface 141D of the second optical anisotropy layer 14D on the side of the first optical anisotropy layer 12D.

[0175] As described above, the second optical anisotropy layer 14D 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 15-16, the in-plane slow axis at the surface 141D of the second optical anisotropy layer 14D on the side of the first optical anisotropy layer 12D and the in-plane slow axis at the surface 142D of the second optical anisotropy layer 14D opposite to the side of the first optical anisotropy layer 12D form the twist angle described above (80° in Figure 15). In other words, the angle φd2 between the in-plane slow axis at the surface 141D of the second optical anisotropy layer 14D on the side of the first optical anisotropy layer 12D and the in-plane slow axis at the surface 142D opposite to the side of the first optical anisotropy layer 12D is 80°. More specifically, the torsion direction of the disc-shaped liquid crystal compound in the second optical anisotropy layer 14D is left-handed (counterclockwise), 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 142D of the second optical anisotropy layer 14D opposite to the polarizer 20 side is 5°. In Figures 15-16, the torsion angle of the disc-shaped liquid crystal compound in the second optical anisotropy layer 14D is shown to be 80°. However, the invention is not limited to this embodiment, and the torsion angle of the disc-shaped liquid crystal compound can be in the range of 80±30°. In other words, it is preferable that the angle between the in-plane slow axis on the surface 141D of the second optical anisotropy layer 14D on the side of the first optical anisotropy layer 12D and the in-plane slow axis on the surface 142D of the second optical anisotropy layer 14D opposite to the side of the first optical anisotropy layer 12D is within the range of 80±30°.

[0176] Furthermore, as shown in Figure 15, the in-plane slow axis at the surface 142D of the second optical anisotropy layer 14D on the side of the third optical anisotropy layer 16D is parallel to the in-plane slow axis at the surface 161D of the third optical anisotropy layer 16D on the side of the second optical anisotropy layer 14D.

[0177] As described above, the third optical anisotropy layer 16D 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 15-16, the in-plane slow axis at the surface 161D of the third optical anisotropy layer 16D on the side of the second optical anisotropy layer 14D and the in-plane slow axis at the surface 162D of the third optical anisotropy layer 16D opposite to the side of the second optical anisotropy layer 14D form the twist angle described above (175° in Figure 15). In other words, the angle φd3 between the in-plane slow axis at the surface 161D of the third optical anisotropy layer 16D on the side of the second optical anisotropy layer 14D and the in-plane slow axis at the surface 162D opposite to the side of the second optical anisotropy layer 14D is 175°. More specifically, the torsion direction of the disc-shaped liquid crystal compound in the third optical anisotropy layer 16D is left-handed (counterclockwise), and the torsion angle is 175°. Therefore, the angle between the absorption axis of the polarizer 20 and the in-plane slow phase axis on the surface 162D of the third optical anisotropy layer 16D opposite to the polarizer 20 side is 180°. In Figures 15-16, the torsion angle of the disc-shaped liquid crystal compound in the third optical anisotropy layer 16D is shown to be 175°. However, the model is not limited to this model, and it is preferable that the torsion angle of the disc-shaped liquid crystal compound be within the range of 175 ± 30°. In other words, it is preferable that the angle between the in-plane slow axis on the surface 161D of the third optical anisotropy layer 16D on the side of the second optical anisotropy layer 14D and the in-plane slow axis on the surface 162D of the third optical anisotropy layer 16D opposite to the side of the second optical anisotropy layer 14D is within the range of 175 ± 30°.

[0178] As described above, in the embodiments shown in Figures 15-16, when the circular polarizer 100D is observed from the phase difference film 10D side, the in-plane slow axis of the first optical anisotropy layer 12D is rotated 75° counterclockwise with respect to the absorption axis of the polarizer 20, the twist direction of the rod-shaped liquid crystal compound in the second optical anisotropy layer 14D is counterclockwise (left twist), and the twist direction of the disc-shaped liquid crystal compound in the third optical anisotropy layer 16D is counterclockwise (left twist). In FIGS. 15 to 16, although the twisting direction of the liquid crystal compound has been described in detail in the counterclockwise mode, it may be in the clockwise mode as long as the relationship of a predetermined angle is satisfied. More specifically, when observing the circular polarizing plate 100D from the retardation film 10D side, with the absorption axis of the polarizer 20 as a reference, the in-plane slow axis of the first optically anisotropic layer 12D is rotated clockwise by 75°, and the twisting direction of the rod-like liquid crystal compound in the second optically anisotropic layer 14D may be clockwise (right twist), and the twisting direction of the disc-like liquid crystal compound in the third optically anisotropic layer 16D may be clockwise (right twist).

[0179] That is, in a circular polarizing plate including the fourth embodiment of the retardation film, when observing the circular polarizing plate from the retardation film side, with the absorption axis of the polarizer as a reference, when the in-plane slow axis of the first optically anisotropic layer is rotated counterclockwise within a range of 75 ± 13° (preferably 75 ± 10°), based on the in-plane slow axis on the surface of the second optically anisotropic layer on the side of the third optically anisotropic layer, it is preferable that the twisting direction of the liquid crystal compound in the second optically anisotropic layer is counterclockwise, and based on the in-plane slow axis on the surface of the third optically anisotropic layer on the side opposite to the second optically anisotropic layer side, the twisting direction of the liquid crystal compound in the second optically anisotropic layer is counterclockwise. Also, in a circular polarizing plate including the fourth embodiment of the retardation film, when observing the circular polarizing plate from the retardation film side, with the absorption axis of the polarizer as a reference, when the in-plane slow axis of the first optically anisotropic layer is rotated clockwise within a range of 75 ± 13° (preferably 75 ± 10°), based on the in-plane slow axis on the surface of the second optically anisotropic layer on the side of the third optically anisotropic layer, it is preferable that the twisting direction of the liquid crystal compound in the second optically anisotropic layer is clockwise, and based on the in-plane slow axis on the surface of the third optically anisotropic layer on the side opposite to the second optically anisotropic layer side, the twisting direction of the liquid crystal compound in the second optically anisotropic layer is clockwise.

[0180] The above circular polarizing plate may have other members other than the retardation film and the polarizer. The circular polarizing plate may have an adhesion layer between the retardation film and the polarizer. Examples of the adhesion layer include a known adhesive layer and an adhesive agent layer.

[0181] The manufacturing method of the above circular polarizing plate is not particularly limited, and known methods can be mentioned. For example, a method of bonding a polarizer and a retardation film through an adhesive layer can be mentioned.

[0182] <Use> The above-mentioned retardation film can be applied to various uses. For example, by adjusting the optical characteristics of each optically anisotropic layer, it can also be used as a so-called λ / 4 plate or λ / 2 plate. Note that a λ / 4 plate is a plate having a function of converting linearly polarized light of a specific wavelength into circularly polarized light (or converting circularly polarized light into linearly polarized light). More specifically, it is a plate in which the in-plane retardation Re at a predetermined wavelength λ nm indicates λ / 4 (or an odd multiple thereof). The in-plane retardation (Re(550)) of the λ / 4 plate at a wavelength of 550 nm may have an error of about 25 nm around the ideal value (137.5 nm). For example, it is preferably 110 to 160 nm, and more preferably 120 to 150 nm. In addition, a λ / 2 plate refers to an optically anisotropic film in which the in-plane retardation Re(λ) at a specific wavelength λ nm satisfies Re(λ)≒λ / 2. This formula only needs to be achieved at any wavelength in the visible light region (for example, 550 nm). Among them, it is preferable that the in-plane retardation Re(550) at a wavelength of 550 nm satisfies the following relationship. 210 nm ≦ Re(550) ≦ 300 nm

[0183] <Display device> The retardation film (first to fourth embodiments) and the circular polarizing plate (first to fourth embodiments) of the present invention can be suitably applied to a display device. The display device of the present invention includes an image display element and the above-mentioned retardation film or circular polarizing plate. When applying the retardation film of the present invention to a display device, it is preferably applied as the above-mentioned circular polarizing plate. In this case, the circular polarizing plate is arranged on the viewing side, and among the circular polarizing plate, the polarizer is arranged on the viewing side. The image display element is not particularly limited and includes organic electroluminescent display elements and liquid crystal display elements. [Examples]

[0184] 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.

[0185] <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).

[0186] ------------------------------------------------------------------ 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) ------------------------------------------------------------------

[0187] [ka]

[0188]

Chem.

[0189] The dope prepared above was cast using a drum film former. The dope was cast from a die so as to contact a metal support cooled to 0 °C, and then the obtained web (film) was peeled off. The drum was made of SUS.

[0190] After the web (film) obtained by casting was peeled off from the drum, it was dried in a tenter device for 20 minutes at 30 - 40 °C inside the tenter device that clips both ends of the web with clips during film conveyance. Subsequently, the web was post-dried by zone heating while being roll-conveyed. After the obtained web was nicked, it was wound up. The obtained cellulose acetate film had a film thickness of 40 μm, an in-plane retardation of 1 nm at a wavelength of 550 nm, and a thickness-direction retardation of 26 nm at a wavelength of 550 nm.

[0191] (Formation of alignment film) An optical alignment film forming material described in Example 1 of WO2020 / 050305 was coated on the above-prepared long cellulose acetate film. Then, the coating film was heated to 120 °C with warm air to be hardened. Next, the coating film was irradiated with polarized ultraviolet light of 365 nm to obtain an optical alignment film.

[0192] (Formation of optically anisotropic layer (1c)) An optically anisotropic layer forming composition (1c) containing a rod-like liquid crystal compound with the following composition was coated on the above-prepared optical alignment film using a kiss coater and heated with warm air at 80 °C for 60 seconds. Subsequently, the obtained composition layer was subjected to UV irradiation (500 mJ / cm 2 ) at 80 °C to fix the alignment of the liquid crystal compound and form an optically anisotropic layer (1c) corresponding to optically anisotropic layer Z. The optically anisotropic layer (1c) had a thickness of 0.9 μm, a Δnd of 125 nm at a wavelength of 550 nm, and a torsion angle of 175° for the liquid crystal compound. When the width direction of the film 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 185° on the air side and 0° on the side in contact with the cellulose acylate film. The in-plane slow phase axis direction of the optically anisotropic layer is expressed by observing the substrate from the surface side of the optically anisotropic layer, with the width direction of the cellulose acylate film (the substrate) set as 0°, and clockwise (rightward) rotation being negative and counterclockwise (leftward) rotation being positive.

[0193] -------------------------------------------------- Composition for forming optically anisotropic layer (1c) -------------------------------------------------- 100 parts by mass of the following 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): 1.68 parts by mass 0.08 parts by mass of the following fluorine-containing compound C 0.50 parts by mass of the polymer (A) below Methyl ethyl ketone 156 parts by mass --------------------------------------------------

[0194] Rod-shaped liquid crystal compound (A) (hereinafter referred to as a mixture of compounds)

[0195] [ka]

[0196] Left-handed chiral agent (L1)

[0197] [ka]

[0198] Fluorine-containing compound C (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 25% by mass, the content of the repeating unit in the middle was 25% by mass, and the content of the repeating unit on the right was 50% by mass.)

[0199] [ka]

[0200] 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.)

[0201] [ka]

[0202] (Formation of optically anisotropic layer (1b)) The optically anisotropic layer (1c) 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 rotated 95° counterclockwise with respect to the longitudinal direction of the film.

[0203] On the optically anisotropic layer (1c) that had undergone the rubbing treatment described above, an optically anisotropic 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 hot air at 110°C for 2 minutes to dry the solvent and to allow the disc-shaped liquid crystal compound to be oriented and matured. Then, the obtained composition layer was subjected to UV irradiation (500 mJ / cm²) at 80°C. 2 The orientation of the liquid crystal compound was fixed by performing the following procedure, and an optical anisotropic layer (1b) corresponding to the optical anisotropic layer Y was formed. The optically anisotropic layer (1b) 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°), when viewed from the optically anisotropic layer (1c) side, the in-plane slow axis direction was 104° on the air side and 185° on the side in contact with the optically anisotropic layer (1c). 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.

[0204] -------------------------------------------------- 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 0.21 parts by mass of the above fluorine-containing compound C The following left-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 --------------------------------------------------

[0205] Disc-shaped liquid crystal compound 1

[0206] [ka]

[0207] Disc-shaped liquid crystal compound 2

[0208] [ka]

[0209] Orientation film interface orientation agent 1

[0210] [ka]

[0211] Fluorine-containing compound A (In the formula below, a and b represent the content (mass%) of each repeating unit relative to the total repeating units, where a represents 90% by mass and b represents 10% by mass.)

[0212] [ka]

[0213] Fluorine-containing compound B (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 32.5% by mass, and the content of the repeating unit on the right was 67.5% by mass.)

[0214] [ka]

[0215] Left-hand torsional chiral agent (L2)

[0216] [ka]

[0217] Following the procedure described above, a laminate (1b-1c) was fabricated in which an optically anisotropic layer (1c) and an optically anisotropic layer (1b) were laminated on a cellulose acylate film.

[0218] (Formation of optically anisotropic layer (1a)) Next, an optical anisotropic layer-forming composition (1a) containing a rod-shaped liquid crystal compound of the following composition was applied to the optical anisotropic layer (1b) of the laminate (1b-1c) prepared above using a Gieser coating machine, and heated with 80°C hot air for 60 seconds. Subsequently, the resulting composition layer was irradiated with UV light (500 mJ / cm²) at 80°C. 2 The orientation of the liquid crystal compound was fixed by performing the following procedure, and an optical anisotropic layer (1a) corresponding to the optical anisotropic layer X was formed. The thickness of the optically anisotropic layer (1a) was 1.2 μm. The in-plane retardation at 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 with respect to the film plane. Furthermore, assuming the film width direction is 0° (the long direction is 90° counterclockwise and -90° clockwise), the in-plane slow phase axis direction, when viewed from the optically anisotropic layer (1a) side, was 104°.

[0219] -------------------------------------------------- Composition for forming an optically anisotropic layer (1a) -------------------------------------------------- 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 --------------------------------------------------

[0220] Following the procedure described above, a laminate (1a-1b-1c) was fabricated in which an optically anisotropic layer (1c), an optically anisotropic layer (1b), and an optically anisotropic layer (1a) were laminated on a long cellulose acylate film.

[0221] <Example 2> (Formation of optically anisotropic layer (2c)) A photo-oriented film was obtained on a long cellulose acylate film in the same manner as in Example 1 described above. On the photo-alignment film prepared above, an optically anisotropic layer-forming composition (2c) 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 liquid crystal compound was fixed by performing the following procedure, and an optical anisotropic layer (2c) corresponding to the optical anisotropic layer Z was formed. The optically anisotropic layer (2c) had a thickness of 0.8 μm, a Δnd of 135 nm at a wavelength of 550 nm, and a torsion angle of 175° for the liquid crystal compound. When the film width direction was set to 0° (longitudinal direction to 90°), the in-plane slow phase axis direction, when viewed from the optically anisotropic layer (2c) side, was 95° on the air side and 270° on the side in contact with the cellulose acylate film. 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.

[0222] -------------------------------------------------- Composition for forming optically anisotropic layer (2c) -------------------------------------------------- 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 0.78 parts by mass of the above left-handed chiral agent (L2) 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 --------------------------------------------------

[0223] (Formation of optically anisotropic layer (2b)) On the optically anisotropic layer (2c) prepared above, an optically anisotropic layer-forming composition (2b) containing a rod-shaped liquid crystal compound of the following composition was applied using a Gieser coating machine and heated with hot air at 80°C 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 anisotropic layer (2b) corresponding to the optical anisotropic layer Y was formed. The optically anisotropic layer (2b) had a thickness of 1.2 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°), when viewed from the optically anisotropic layer (2b) side, the in-plane slow phase axis direction was 14° on the air side and 95° on the side in contact with the optically anisotropic layer (2c). 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.

[0224] -------------------------------------------------- Composition for forming an optically anisotropic layer (2b) -------------------------------------------------- 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 0.60 parts by mass of the above left-handed chiral agent (L1) 0.08 parts by mass of the above fluorine-containing compound C 0.50 parts by mass of the above polymer (A) Methyl ethyl ketone 156 parts by mass --------------------------------------------------

[0225] Following the procedure described above, a laminate (2b-2c) was fabricated in which an optically anisotropic layer (2c) and an optically anisotropic layer (2b) were laminated on a cellulose acylate film.

[0226] (Formation of optically anisotropic layer (2a)) The optically anisotropic layer (2b) of the laminate (2b-2c) prepared above was continuously rubbed. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle between the longitudinal direction of the film (transport direction) and the rotation axis of the rubbing roller was set to 76°. If the longitudinal direction of the film (transport direction) is set to 90°, and when observed from the film side, with the film width direction as the reference (0°) and clockwise direction represented as a positive value, the rotation axis of the rubbing roller is at 14°. In other words, the position of the rotation axis of the rubbing roller is the position obtained by rotating 76° counterclockwise with respect to the longitudinal direction of the film.

[0227] On the optically anisotropic layer (2b) that had undergone the rubbing treatment 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 allow the disc-shaped liquid crystal compound to be oriented and matured. Then, the obtained composition layer was subjected to UV irradiation (500 mJ / cm²) at 80°C. 2 The orientation of the liquid crystal compound was fixed by performing the following procedure, and an optical anisotropic layer (2a) corresponding to the optical anisotropic layer X was formed. The thickness of the optically anisotropic layer (2a) was 1.1 μm. The in-plane retardation at 550 nm was 168 nm. The average inclination angle of the disc surface of the disc-shaped liquid crystal compound with respect to the film surface was 90°, confirming that it was oriented perpendicular to the film surface. Furthermore, the angle of the slow phase axis of the optically anisotropic layer (2a) was parallel to the rotation axis of the rubbing roller. Assuming the film width direction is 0° (the longitudinal direction is 90° counterclockwise and -90° clockwise), the in-plane slow phase axis direction, when viewed from the optically anisotropic layer (2a) side, was 14°.

[0228] -------------------------------------------------- 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 0.55 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 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 --------------------------------------------------

[0229] Following the procedure described above, a laminate (2a-2b-2c) was fabricated in which an optically anisotropic layer (2c), an optically anisotropic layer (2b), and an optically anisotropic layer (2a) were laminated on a long cellulose acylate film.

[0230] <Example 3> (Formation of optically anisotropic layer (3c)) A photo-aligned film was formed on a long cellulose acylate film in the same manner as in Example 1 described above. On the photo-alignment film prepared above, the optical anisotropy layer-forming composition (1b) containing the disc-shaped liquid crystal compound of Example 1 was applied at varying thicknesses 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 liquid crystal compound was fixed by performing the following procedure, and an optical anisotropic layer (3c) corresponding to the optical anisotropic layer Z was formed. The optically anisotropic layer (3c) had a thickness of 0.6 μm, a Δnd of 82 nm at a wavelength of 550 nm, and a torsion angle of 40.5° of the liquid crystal compound. When the film width direction was set to 0° (longitudinal direction to 90°), the in-plane slow phase axis direction, when viewed from the optically anisotropic layer (3c) side, was 54.5° on the air side and 95° on the side in contact with the cellulose acylate film. 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.

[0231] (Formation of optically anisotropic layer (3b)) On the optically anisotropic layer (3c) prepared above, the optically anisotropic layer-forming composition (2b) containing the rod-shaped liquid crystal compound of Example 2 was applied at varying thicknesses 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 ) was performed to fix the alignment of the liquid crystal compound, and an optically anisotropic layer (3b) corresponding to the optically anisotropic layer Y was formed. The thickness of the optically anisotropic layer (3b) was 0.6 μm, Δnd at a wavelength of 550 nm was 82 nm, and the twist angle of the liquid crystal compound was 40.5°. When the width direction of the film was 0° (the longitudinal direction was 90°), when viewed from the side of the optically anisotropic layer (3b), the in-plane slow axis direction was 14° on the air side and 54.5° on the side contacting the optically anisotropic layer (2c). Note that the in-plane slow axis direction of the optically anisotropic layer is represented with the width direction of the substrate as the reference 0°, observing the substrate from the surface side of the optically anisotropic layer, with clockwise (rightwise) being negative and counterclockwise (leftwise) being positive.

[0232] By the above procedure, a laminate (3b-3c) in which the optically anisotropic layer (3c) and the optically anisotropic layer (3b) were laminated was produced on the cellulose acetate film.

[0233] (Formation of the optically anisotropic layer (3a-3a’)) The optically anisotropic layer (3b) of the above-produced laminate (3b-3c) was continuously rubbed. At this time, the longitudinal direction of the long film and the conveyance direction were parallel, and the angle formed by the longitudinal direction (conveyance direction) of the film and the rotation axis of the rubbing roller was 76°. When the longitudinal direction (conveyance direction) of the film was 90°, and observing from the film side with the film width direction as the reference (0°) and the clockwise direction represented by a positive value, the rotation axis of the rubbing roller was at 14°. In other words, the position of the rotation axis of the rubbing roller was the position rotated counterclockwise by 76° based on the longitudinal direction of the film.

[0234] On the above-rubbed optically anisotropic layer (3b), using a kiss coater, the composition for forming an optically anisotropic layer (2a) containing the disk-shaped liquid crystal compound of Example 2 was applied with different thicknesses to form a composition layer. Then, the obtained composition layer was heated with warm air at 110°C for 2 minutes for drying the solvent and aging the alignment of the disk-shaped liquid crystal compound. Subsequently, the obtained composition layer was irradiated with UV at 80°C (500 mJ / cm 2By performing this procedure, the orientation of the liquid crystal compound was fixed, and an optical anisotropic layer (3a) corresponding to a part of the optical anisotropic layer X was formed. The thickness of the optically anisotropic layer (3a) was 0.8 μm. The in-plane retardation at a wavelength of 550 nm was 128 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 slow phase axis of the optically anisotropic layer (2a) was parallel to the rotation axis of the rubbing roller. Assuming the film width direction is 0° (the longitudinal direction is 90° counterclockwise and -90° clockwise), the in-plane slow phase axis direction, when viewed from the optically anisotropic layer (3a) side, was 14°.

[0235] A laminate (3a-3b-3c) was fabricated by laminating an optically anisotropic layer (3c), an optically anisotropic layer (3b), and an optically anisotropic layer (3a) on a cellulose acylate film using the above procedure.

[0236] On the optically anisotropic layer (3a) of the laminate (3a-3b-3c) prepared above, the optically anisotropic layer-forming composition (1a) containing the rod-shaped liquid crystal compound of Example 1 was applied at varying thicknesses 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 anisotropic layer (3a') corresponding to a part of the optical anisotropic layer (A) was formed. The thickness of the optically anisotropic layer (3a') was 0.3 μm. The in-plane retardation at a wavelength of 550 nm was 40 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. Furthermore, assuming the film width direction is 0° (the longitudinal direction is 90° counterclockwise and -90° clockwise), the in-plane slow phase axis direction, when viewed from the optically anisotropic layer (3a') side, was 14°.

[0237] Following the procedure described above, a laminate (3a'-3a-3b-3c) was fabricated by laminating optically anisotropic layers (3c), (3b), (3a), and (3a') on a long cellulose acylate film.

[0238] <Example 4> (Formation of optically anisotropic layer (4c)) A photo-aligned film was formed on a long cellulose acylate film in the same manner as in Example 1 described above. On the photo-alignment film prepared above, the optical anisotropy layer-forming composition (2b) containing the rod-shaped liquid crystal compound of Example 2 was applied to the film at varying thicknesses 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 anisotropic layer (4c) corresponding to the optical anisotropic layer Z was formed. The optically anisotropic layer (4c) had a thickness of 0.6 μm, a Δnd of 82 nm at a wavelength of 550 nm, and a torsion angle of 40.5° of the liquid crystal compound. When the film width direction is 0° (longitudinal direction is 90°), the in-plane slow phase axis direction, when viewed from the optically anisotropic layer (4c) side, was 144.5° on the air side and 185° on the side in contact with the cellulose acylate film. 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.

[0239] (Formation of optically anisotropic layer (4b)) The optically anisotropic layer (4c) 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 54.5°. 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 144.5°. In other words, the position of the rotation axis of the rubbing roller is the position obtained by rotating 54.5° counterclockwise with respect to the longitudinal direction of the film.

[0240] On the optically anisotropic layer (4c) that had undergone the rubbing treatment described above, the optically anisotropic layer-forming composition (1b) containing the disc-shaped liquid crystal compound of Example 1 was applied at varying thicknesses 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 orient and mature. 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 anisotropic layer (4b) corresponding to the optical anisotropic layer Y was formed. The optically anisotropic layer (4b) had a thickness of 0.6 μm, a Δnd of 82 nm at a wavelength of 550 nm, and a torsion angle of 40.5° of the liquid crystal compound. When the film width direction is 0° (longitudinal direction is 90°), the in-plane slow phase axis direction, when viewed from the optically anisotropic layer (4b) side, was 104° on the air side and 144.5° on the side in contact with the optically anisotropic layer (4c). 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.

[0241] Following the procedure described above, a laminate (4b-4c) was fabricated in which an optically anisotropic layer (4c) and an optically anisotropic layer (4b) were laminated on a cellulose acylate film.

[0242] (Formation of optically anisotropic layer (4a-4a')) An optical anisotropic layer-forming composition (4a) containing a rod-shaped liquid crystal compound of the following composition was applied to the optical anisotropic layer (4b) of the laminate (4b-4c) prepared above, and heated with hot air at 80°C 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 anisotropic layer (4a) corresponding to a part of the optical anisotropic layer X was formed. The thickness of the optically anisotropic layer (4a) was 0.9 μm. The in-plane retardation at 550 nm was 128 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 0°, confirming that it was oriented horizontally with respect to the film surface. Furthermore, assuming the film width direction is 0° (the longitudinal direction is 90° counterclockwise and -90° clockwise), the slow axis was 104° when viewed from the optically anisotropic layer (4a) side.

[0243] -------------------------------------------------- Composition for forming optically anisotropic layer (4a) -------------------------------------------------- 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 0.50 parts by mass of the polymer (A) below Methyl ethyl ketone 156 parts by mass --------------------------------------------------

[0244] A laminate (4a-4b-4c) was fabricated by laminating an optically anisotropic layer (4c), an optically anisotropic layer (4b), and an optically anisotropic layer (4a) on a cellulose acylate film using the above procedure.

[0245] The optically anisotropic layer (4a) of the laminate (4a-4b-4c) prepared above was continuously rubbed. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the angle between the longitudinal direction of the film (transport direction) and the rotation axis of the rubbing roller was set to 76°. If the longitudinal direction of the film (transport direction) is set to 90°, and when observed from the film side, with the film width direction as the reference (0°) and clockwise direction represented as a positive value, the rotation axis of the rubbing roller is at 14°. In other words, the position of the rotation axis of the rubbing roller is the position obtained by rotating 76° counterclockwise with respect to the longitudinal direction of the film.

[0246] On the optically anisotropic layer (4a) that had undergone the rubbing treatment described above, the optically anisotropic layer-forming composition (2a) containing the disc-shaped liquid crystal compound of Example 2 was applied at varying thicknesses 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 undergo orientation maturation. Subsequently, the obtained composition layer was subjected to UV irradiation (500 mJ / cm²) at 80°C. 2 The orientation of the liquid crystal compound was fixed by performing the following procedure, and an optical anisotropic layer (4a') corresponding to a part of the optical anisotropic layer X was formed. The thickness of the optically anisotropic layer (4a') was 0.3 μm. The in-plane retardation 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 90°, confirming that it was oriented perpendicular to the film surface. Furthermore, the angle of the slow phase axis of the optically anisotropic layer (4a') was perpendicular to the rotation axis of the rubbing roller. Assuming the film width direction is 0° (the longitudinal direction is 90° counterclockwise and -90° clockwise), the in-plane slow phase axis direction, when viewed from the optically anisotropic layer (4a') side, was 104°.

[0247] Following the procedure described above, a laminate (4a'-4a-4b-4c) was fabricated by laminating optically anisotropic layers (4c), (4b), (4a), and (4a') on a long cellulose acylate film.

[0248] <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.

[0249] (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.

[0250] <Fabrication of circular polarizing plates> The surface of the optically anisotropic layer X contained in the long optical film prepared in Examples 1 to 4 above, i.e., the optically anisotropic layer (1a), optically anisotropic layer (2a), optically anisotropic layer (3a'), or optically anisotropic layer (4a'), was continuously bonded to the surface of the polarizer of the long linear polarizing plate prepared above (the side opposite the polarizer protective film) using an ultraviolet-curing adhesive. Next, the cellulose acylate film and photoalignment film on the optically anisotropic layer C, i.e., optically anisotropic layer (1c), optically anisotropic layer (2c), optically anisotropic layer (3c), or optically anisotropic layer (4c), were peeled off, exposing the surface of optically anisotropic layer Z that was in contact with the cellulose acylate film. In this way, circular polarizers (P1-P4) were fabricated, consisting of the optical films and linear polarizers of Examples 1-4, with the polarizer protective film, polarizer, optical anisotropy layer X, optical anisotropy layer Y, and optical anisotropy layer Z laminated in this order. At this time, with the width direction as the reference 0°, the absorption axis of the polarizer was 90° and coincided with the longitudinal direction. In the circular polarizer (P1) containing the optical film prepared in Example 1, the relationship between the absorption axis of the polarizer and the in-plane slow axis of each optical anisotropy layer was as described in Figures 10-12 above. In the circular polarizer (P2) containing the optical film prepared in Example 2, the relationship between the absorption axis of the polarizer and the in-plane slow axis of each optical anisotropy layer was as described in Figures 14-16 above. In the circular polarizer (P3) containing the optical film prepared in Example 3, the relationship between the absorption axis of the polarizer and the in-plane slow axis of each optical anisotropy layer was as described in Figures 2 to 4 above. In the circular polarizer (P4) containing the optical film prepared in Example 4, the relationship between the absorption axis of the polarizer and the in-plane slow axis of each optical anisotropy layer was as described in Figures 6 to 8 above.

[0251] <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, on a long cellulose acylate film. At this time, the retardation of the optically anisotropic layer (h1) at a wavelength of 550 nm was 181 nm, and when the film width direction was set to 0° (longitudinal direction to 90°), the slow axis was -13° when viewed from the optically anisotropic layer (h1) side. 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 set to 0° (longitudinal direction to 90°), the in-plane slow 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.

[0252] <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 removed, and the circular polarizer prepared as described above was attached to the display device using a pressure-sensitive adhesive so that the polarizer protective film was positioned on the outside.

[0253] [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.

[0254] (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 difference in color is visible but within an acceptable range, and the reflected light is small, so there are no problems with use. (Acceptable) C: The color difference is visible, and the reflected light is also significant; this is unacceptable.

[0255] [Table 1]

[0256] As shown in Table 1 above, the optical 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 optical 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. [Explanation of Symbols]

[0257] 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 Fourth optical anisotropy layer 20 polarizers 100A, 100B, 100C, 100D Circular Polarizing Plates

Claims

1. It includes optically anisotropic layer X, optically anisotropic layer Y, and optically anisotropic layer Z in this order. The optically anisotropic layer X is plate A, The optically anisotropic layer Y is a layer in which a first liquid crystal compound is fixed in a torsion orientation along a helical axis extending in the thickness direction. The optically anisotropic layer Z is a layer in which a second liquid crystal compound is fixed in a torsion orientation along a helical axis extending in the thickness direction. One of the first liquid crystal compound and the second liquid crystal compound is a rod-shaped liquid crystal compound, and the other is a disc-shaped liquid crystal compound. A phase difference film in which the in-plane slow axis of the optical anisotropic layer X is parallel to the in-plane slow axis of the optical anisotropic layer Y on the surface facing the optical anisotropic layer X.

2. The optically anisotropic layer X includes a positive A plate and a negative A plate. When the positive A plate and the negative A plate are arranged in this order from the surface of the optical anisotropy layer X opposite to the optical anisotropy layer Y side, the first liquid crystal compound is a rod-shaped liquid crystal compound, and the second liquid crystal compound is a disc-shaped liquid crystal compound. The phase difference film according to claim 1, wherein when the negative A plate and the positive A plate are arranged in this order from the surface of the optical anisotropy layer X opposite to the optical anisotropy layer Y side, the first liquid crystal compound is a disc-shaped liquid crystal compound and the second liquid crystal compound is a rod-shaped liquid crystal compound.

3. The in-plane retardation of plate A on the side of the optical anisotropy layer X opposite to the optical anisotropy layer Y is 20 to 90 nm at a wavelength of 550 nm. The phase difference film according to claim 2, wherein the in-plane retardation of the A plate on the optical anisotropy layer Y side of the optical anisotropy layer X at a wavelength of 550 nm is 70 to 200 nm.

4. The phase difference film according to claim 2, wherein the twist angle of the first liquid crystal compound is within the range of 40 ± 20°.

5. The phase difference film according to claim 2, wherein the twist angle of the second liquid crystal compound is within the range of 40 ± 20°.

6. The phase difference film according to claim 2, wherein the product Δnd of the refractive index anisotropy Δn of the optical anisotropy layer Y at a wavelength of 550 nm and the thickness d of the optical anisotropy layer Y is 50 to 120 nm.

7. The phase difference film according to claim 2, wherein the product Δnd of the refractive index anisotropy Δn of the optical anisotropy layer Z at a wavelength of 550 nm and the thickness d of the optical anisotropy layer Z is 50 to 120 nm.

8. The optical anisotropy layer X is a positive A plate or a negative A plate, When the optically anisotropic layer X is a positive A plate, the first liquid crystal compound is a disc-shaped liquid crystal compound, and the second liquid crystal compound is a rod-shaped liquid crystal compound. The phase difference film according to claim 1, wherein, when the optical anisotropy layer X is a negative A plate, the first liquid crystal compound is a rod-shaped liquid crystal compound and the second liquid crystal compound is a disc-shaped liquid crystal compound.

9. The phase difference film according to claim 8, wherein the in-plane retardation of the optical anisotropy layer X at a wavelength of 550 nm is 120 to 240 nm.

10. The phase difference film according to claim 8, wherein the torsion angle of the first liquid crystal compound is 80 ± 30°.

11. The phase difference film according to claim 8, wherein the twist angle of the second liquid crystal compound is 175 ± 30°.

12. The phase difference film according to claim 8, wherein the product Δnd of the refractive index anisotropy Δn of the optical anisotropy layer Y at a wavelength of 550 nm and the thickness d of the optical anisotropy layer Y is 120 to 240 nm.

13. The phase difference film according to claim 8, wherein the product Δnd of the refractive index anisotropy Δn of the optical anisotropy layer Z at a wavelength of 550 nm and the thickness d of the optical anisotropy layer Z is 70 to 190 nm.

14. A circular polarizer comprising a polarizer and a phase difference film according to any one of claims 1 to 13.

15. A display device comprising a phase difference film according to any one of claims 1 to 13.

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