Circular polarizer, display device

Abstract

To provide a circular polarizing plate and a display device with which, when a display device obtained by pasting the circular polarizing plate to a display element is turned to black display and viewed from the front direction under a sunlight environment, tinting by a black color is suppressed.SOLUTION: Provided is a circular polarizing plate comprising a polarizer, a first optical anisotropic layer, and a second optical anisotropic layer in this order, the first optical anisotropic layer being a layer formed by fixing a liquid crystal compound that is torsion oriented along a spiral axis that extends in the thickness direction, the second optical anisotropic layer being a plate A, the absorption axis of the polarizer and the in-plane slow axis of the second optical anisotropic layer being parallel or orthogonal to each other, the first optical anisotropic layer and second optical anisotropic layer exhibiting prescribed optical characteristics.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Circular polarizers containing retardation films with refractive index anisotropy are used in various applications such as image display devices. More specifically, circular polarizers are used in organic electroluminescence (EL) displays and LCD displays to suppress the adverse effects of external light reflection. For example, Patent Document 1 discloses a circular polarizing plate having, in that order, a polarizing film, a first optically anisotropic layer exhibiting predetermined optical properties, and a second optically anisotropic layer exhibiting predetermined optical properties, and indicates that a coloring (black coloring) that appears when black is mixed with other colors when viewed from the front in a display device including the circular polarizing plate is suppressed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5966079 Summary of the Invention [Problem to be solved by the invention]

[0004] On the other hand, the present inventors evaluated the characteristics of a display device including the circular polarizer described in Patent Document 1 by displaying black under harsher conditions, such as under sunlight, and found that a black tint was observed when viewed from the front, indicating that there is room for improvement.

[0005] In view of the above-described circumstances, an object of the present invention is to provide a circularly polarizing plate that suppresses black tinting when the display device obtained by attaching the circularly polarizing plate to a display element displays black and is viewed from the front in a sunlight environment. Another object of the present invention is to provide a display device. [Means for solving the problem]

[0006] As a result of extensive research into the problems of the prior art, the present inventors have found that the above-mentioned problems can be solved by the following configuration.

[0007] (1) A circularly polarizing plate having a polarizer, a first optically anisotropic layer, and a second optically anisotropic layer in this order, the first optically anisotropic layer is a layer in which liquid crystal compounds are fixed and twisted along a helical axis extending in the thickness direction; the second optically anisotropic layer is an A plate, the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are parallel or perpendicular to each other; the value of the product Δnd of the refractive index anisotropy Δn of the first optically anisotropic layer at a wavelength of 550 nm and the thickness d of the first optically anisotropic layer satisfies the relationship of formula (1) described below, the in-plane retardation Re(550) of the second optically anisotropic layer at a wavelength of 550 nm satisfies the relationship of formula (2) described below, When the circular polarizing plate is observed from the polarizer side, and the absorption axis of the polarizer is taken as 90°, and a counterclockwise rotation is expressed as a positive angle value, the angle of the in-plane slow axis on the polarizer-side surface of the first optically anisotropic layer is defined as X. When the circular polarizing plate is observed from the polarizer side, and the in-plane slow axis on the polarizer-side surface of the first optically anisotropic layer is taken as a reference, and a counterclockwise rotation is expressed as a positive angle value and a clockwise rotation is expressed as a negative angle value, the twist angle of the liquid crystal compound in the first optically anisotropic layer is defined as Y. When the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are parallel to each other, X and Y satisfy any one of the requirements 1 to 4 described below, A circularly polarizing plate, wherein X and Y satisfy requirement 5 or 6 described below when the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are perpendicular to each other. (2) the value of the product Δnd of the refractive index anisotropy Δn of the first optically anisotropic layer at a wavelength of 550 nm and the thickness d of the first optically anisotropic layer satisfies the relationship of the below-described formula (1-1), the in-plane retardation Re(550) of the second optically anisotropic layer at a wavelength of 550 nm satisfies the relationship of formula (2-1) described below, When the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are parallel to each other, X and Y satisfy any one of the requirements 1-1 to 4-1 described below, The circularly polarizing plate according to (1), wherein X and Y satisfy requirement 5-1 or 6-1 described below when the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are perpendicular to each other. (3) The circularly polarizing plate according to (1) or (2), wherein the second optically anisotropic layer is a stretched film or a layer in which a liquid crystal compound is fixed. (4) A display device comprising the circular polarizer according to any one of (1) to (3). [Effects of the Invention]

[0008] According to the present invention, a circularly polarizing plate can be provided that suppresses black tinting when the display device obtained by attaching the circularly polarizing plate to a display element is made to display black and viewed from the front in a sunlight environment. The present invention also provides a display device. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view of a circularly polarizing plate according to an embodiment of the present invention; [Figure 2] FIG. 1 is a diagram showing the relationship between the absorption axis of a polarizer and the in-plane slow axes of the first optically anisotropic layer and the second optically anisotropic layer in an embodiment of the circularly polarizing plate of the present invention that satisfies Requirement 1. [Figure 3] 3 is a schematic diagram showing the relationship between the absorption axis of a polarizer and the angle between the in-plane slow axes of a first optically anisotropic layer and a second optically anisotropic layer when observed from the direction of the white arrow in FIG. 2. FIG. [Figure 4] FIG. 1 is a diagram showing the relationship between the absorption axis of a polarizer and the in-plane slow axes of the first optically anisotropic layer and the second optically anisotropic layer in an embodiment of the circularly polarizing plate of the present invention that satisfies Requirement 2. [Figure 5] FIG. 5 is a schematic diagram showing the relationship between the absorption axis of a polarizer and the angle between the in-plane slow axes of a first optically anisotropic layer and a second optically anisotropic layer when observed from the direction of the white arrow in FIG. [Figure 6]FIG. 1 is a diagram showing the relationship between the absorption axis of a polarizer and the in-plane slow axes of the first optically anisotropic layer and the second optically anisotropic layer in an embodiment of the circularly polarizing plate of the present invention that satisfies Requirement 3. [Figure 7] FIG. 7 is a schematic diagram showing the relationship between the absorption axis of a polarizer and the angle between the in-plane slow axes of the first optically anisotropic layer and the second optically anisotropic layer when observed from the direction of the white arrow in FIG. [Figure 8] FIG. 1 is a diagram showing the relationship between the absorption axis of a polarizer and the in-plane slow axes of the first optically anisotropic layer and the second optically anisotropic layer in an embodiment of the circularly polarizing plate of the present invention that satisfies Requirement 4. [Figure 9] 9 is a schematic diagram showing the relationship between the absorption axis of a polarizer and the angle between the in-plane slow axes of the first optically anisotropic layer and the second optically anisotropic layer when observed from the direction of the white arrow in FIG. 8. FIG. [Figure 10] FIG. 10 is a diagram showing the relationship between the absorption axis of a polarizer and the in-plane slow axes of the first optically anisotropic layer and the second optically anisotropic layer in an embodiment of the circularly polarizing plate of the present invention that satisfies Requirement 5. [Figure 11] 11 is a schematic diagram showing the relationship between the absorption axis of a polarizer and the angle between the in-plane slow axes of the first optically anisotropic layer and the second optically anisotropic layer when observed from the direction of the white arrow in FIG. [Figure 12] FIG. 10 is a diagram showing the relationship between the absorption axis of a polarizer and the in-plane slow axes of the first optically anisotropic layer and the second optically anisotropic layer in an embodiment of the circularly polarizing plate of the present invention that satisfies Requirement 6. [Figure 13] 13 is a schematic diagram showing the relationship between the absorption axis of a polarizer and the angle between the in-plane slow axes of the first optically anisotropic layer and the second optically anisotropic layer when observed from the direction of the white arrow in FIG. 12. FIG. DETAILED DESCRIPTION OF THE INVENTION

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

[0011] In the present invention, Re(λ) and Rth(λ) respectively represent the in-plane retardation and the thickness direction retardation at a wavelength λ, which is 550 nm unless otherwise specified. In the present invention, Re(λ) and Rth(λ) are values ​​measured at a wavelength λ using an AxoScan OPMF-1 (manufactured by Optoscience). 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 is calculated. Note that R0(λ) is displayed as a numerical value calculated by AxoScan OPMF-1, but 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 Co., Ltd.) with a sodium lamp (λ=589 nm) as the light source. When measuring wavelength dependency, measurements can be made using a multi-wavelength Abbe refractometer DR-M2 (manufactured by Atago Co., Ltd.) in combination with an interference filter. Alternatively, 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 listed below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), and polystyrene (1.59).

[0013] In this specification, the A-plate is defined as follows. There are two types of A plates: positive A plates and negative A plates. When the refractive index in the in-plane slow axis direction (the direction in which the in-plane refractive index is greatest) of the film is nx, the refractive index in the in-plane direction perpendicular to the in-plane slow axis is ny, and the refractive index in the thickness direction is nz, the positive A plate satisfies the relationship in formula (A1), and the negative A plate satisfies the relationship in formula (A2). Note that the positive A plate has a positive Rth value, and the negative A plate has a negative Rth value. Formula (A1) nx>ny≒nz Formula (A2) ny <nx≒nz The above "≒" not only refers to the case where the two are completely identical, but also to the case where the two are substantially identical. For example, "substantially the same" means that "ny≒nz" ​​also includes the case where (ny-nz)×d (where d is the film thickness) is -10 to 10 nm, preferably -5 to 5 nm, and "nx≒nz" also includes the case where (nx-nz)×d is -10 to 10 nm, preferably -5 to 5 nm.

[0014] In this specification, "visible light" refers to light with a wavelength of 400 to 700 nm, and "ultraviolet light" refers to light with a wavelength of 10 nm or more and less than 400 nm. In addition, in this specification, the terms "perpendicular" and "parallel" include the range of error permitted in the technical field to which the present invention pertains. and This means that the angle is within the precise range of ±5°. do .

[0015] A feature of the circularly polarizing plate of the present invention is that it is used in combination with a predetermined optically anisotropic layer.

[0016] The circular polarizer of the present invention will be described below with reference to the drawings: Figure 1 shows a schematic cross-sectional view of the circular polarizer of the present invention. The circularly polarizing plate 10 has a polarizer 12, a first optically anisotropic layer 14, and a second optically anisotropic layer 16 in this order. The first optically anisotropic layer 14 is a layer in which a liquid crystal compound is fixed and twisted and aligned along a helical axis extending in the thickness direction, and the second optically anisotropic layer 16 is an A plate. Each layer will be described in detail below.

[0017] <Polarizer> The polarizer may be any member that has the function of converting natural light into specific linearly polarized light, and examples thereof include an absorptive polarizer. The type of polarizer is not particularly limited, and any commonly used polarizer can be used, such as an iodine-based polarizer, a dye-based polarizer using a dichroic material, and a polyene-based polarizer. Iodine-based polarizers and dye-based polarizers are generally produced by adsorbing iodine or a dichroic dye into polyvinyl alcohol and stretching the resulting material. A protective film may be disposed on one or both surfaces of the polarizer.

[0018] <First Optically Anisotropic Layer> The first optically anisotropic layer 14 is a layer in which liquid crystal compounds are fixed and twisted along a helical axis extending in the thickness direction. When forming the first optically anisotropic layer 14, it is preferable to use at least a liquid crystal compound and a chiral agent, which will be described later. In this specification, the "fixed" state refers to a state in which the alignment of the liquid crystal compound is maintained. Specifically, it is preferable that the layer has no fluidity and the alignment is not changed by an external field or external force in a temperature range of usually 0 to 50°C, or under more severe conditions, −30 to 70°C, and that the fixed alignment can be stably maintained.

[0019] The twist angle of the liquid crystal compound (the twist angle of the alignment direction of the liquid crystal compound) varies depending on the relationship between the in-plane slow axis of the second optically anisotropic layer 16 and the absorption axis of the polarizer, and will be described in detail later. The torsion angle is measured using an AxoScan (polarimeter) device manufactured by Axometrics and the device analysis software of the same company. Furthermore, the term "twisted alignment of the liquid crystal compound" means that the liquid crystal compound is twisted from one main surface to the other main surface of the first optically anisotropic layer 14 around an axis in the thickness direction of the first optically anisotropic layer 14. Accordingly, the alignment direction (in-plane slow axis direction) of the liquid crystal compound differs depending on the position in the thickness direction of the first optically anisotropic layer 14. When the liquid crystal compound is a rod-shaped liquid crystal compound, in the twisted orientation, the long axis of the rod-shaped liquid crystal compound is preferably arranged parallel to the main surface of the first optically anisotropic layer 14. However, it is not required that they be strictly parallel, and the angle formed between the long axis of the rod-shaped liquid crystal compound and the main surface of the first optically anisotropic layer 14 is preferably in the range of 0±20°, more preferably 0±10°.

[0020] The value of the product Δnd of the refractive index anisotropy Δn of the first optically anisotropic layer 14 at a wavelength of 550 nm and the thickness d of the first optically anisotropic layer 14 satisfies the relationship of formula (1): That is, Δnd is within the range of 317 to 377 nm. Formula (1) 317nm≦Δnd≦377nm In particular, it is preferable that the relationship of formula (1-1) be satisfied in that when a display device obtained by attaching a circularly polarizing plate to a display element is set to black display and viewed from the front in a sunlight environment, black tinting is further suppressed (hereinafter, simply referred to as "the advantage of the present invention being better"). Formula (1-1) 327nm≦Δnd≦367nm The above Δnd is measured using an AxoScan (polarimeter) device from Axometrics and the device analysis software from the same company.

[0021] The type of liquid crystal compound used to form the first optically anisotropic layer 14 is not particularly limited, and known compounds can be used. The liquid crystal compound may be a rod-shaped liquid crystal compound or a discotic liquid crystal compound, with a rod-shaped liquid crystal compound being preferred. Examples of the rod-shaped liquid crystal compound include compounds described in claim 1 of JP-A No. 11-513019 and in paragraphs 0026 to 0098 of JP-A No. 2005-289980. Examples of discotic liquid crystal compounds include compounds described in paragraphs 0020 to 0067 of JP-A No. 2007-108732 and paragraphs 0013 to 0108 of JP-A No. 2010-244038. The liquid crystal compound may have a polymerizable group. The types of polymerizable groups that the liquid crystal compound may have are as described above.

[0022] The first optically anisotropic layer 14 is preferably a layer formed by fixing a liquid crystal compound having a polymerizable group by polymerization. More specifically, it is more preferably a layer formed by fixing a liquid crystal compound (preferably a rod-shaped liquid crystal compound) having a twistedly aligned polymerizable group by polymerization.

[0023] The thickness of the first optically anisotropic layer 14 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. The thickness of the first optically anisotropic layer 14 refers to the average thickness of the first optically anisotropic layer 14. The average thickness is determined by measuring the thickness at any five or more points of the first optically anisotropic layer 14 and calculating the arithmetic average.

[0024] <Second Optically Anisotropic Layer> The second optically anisotropic layer 16 is an A plate. The A plate includes a negative A plate and a positive A plate. The in-plane retardation Re(550) of the second optically anisotropic layer 16 at a wavelength of 550 nm satisfies the relationship of formula (2). Formula (2) 67.5nm≦Re(550)≦127.5nm In particular, it is preferable that the relationship of formula (2-1) is satisfied, in that the effects of the present invention are more excellent. Formula (2-1) 77.5nm≦Re(550)≦117.5nm

[0025] The second optically anisotropic layer 16 may exhibit either forward wavelength dispersion (a property in which in-plane retardation decreases as the measured wavelength increases) or reverse wavelength dispersion (a property in which in-plane retardation increases as the measured wavelength increases). Note that the forward wavelength dispersion and reverse wavelength dispersion are preferably exhibited in the visible light region.

[0026] The second optically anisotropic layer 16 may be a positive A plate or a negative A plate. The second optically anisotropic layer 16 may be a layer in which a liquid crystal compound is fixed, or a stretched film. The layer in which a liquid crystal compound is fixed is preferably a layer in which a rod-like liquid crystal compound in a homogeneous alignment is fixed. In this specification, homogeneous orientation refers to a state in which the molecular axis of a liquid crystal compound (for example, the long axis in the case of a rod-shaped liquid crystal compound) is aligned horizontally and in the same direction relative to the layer surface (optical uniaxiality). Here, horizontal does not necessarily mean strictly horizontal, but means an orientation in which the average molecular axis of the liquid crystal compound forms an inclination angle of less than 20° with respect to the main surface of the layer. Furthermore, the term "same orientation" does not necessarily mean that the orientation is strictly the same, but rather means that when the orientations of the slow axes are measured at any 20 positions within the plane, the maximum difference between the slow axis orientations at the 20 positions (the difference between the two slow axis orientations with the largest difference among the 20 slow axis orientations) is less than 10°.

[0027] Examples of the liquid crystal compound include the liquid crystal compounds exemplified for the first optically anisotropic layer 14. The liquid crystal compound may have a polymerizable group. The types of polymerizable groups that the liquid crystal compound may have are as described above.

[0028] The second optically anisotropic layer 16 is preferably a layer formed by fixing a liquid crystal compound having a polymerizable group by polymerization, and more preferably a layer formed by fixing a liquid crystal compound having a homogeneously oriented polymerizable group by polymerization.

[0029] The thickness of the second optically anisotropic layer 16 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. The thickness of the second optically anisotropic layer 16 refers to the average thickness of the second optically anisotropic layer 16. The average thickness is determined by measuring the thickness of the second optically anisotropic layer 16 at any five or more points and calculating the arithmetic average.

[0030] <Other components> The circularly polarizing plate 10 may include other members in addition to the polarizer 12, the first optically anisotropic layer 14, and the second optically anisotropic layer 16 described above.

[0031] (adhesion layer) The circularly polarizing plate 10 may have an adhesive layer between each of the optically anisotropic layers. Examples of the adhesive layer include known pressure-sensitive adhesive layers and adhesive layers.

[0032] As described in JP-A-11-149015, it is generally preferable to adjust the refractive index of each layer (for example, an optically anisotropic layer) from the viewpoint of suppressing reflection. The difference in refractive index between the layer and the object to be adhered is preferably 0.1 or less, more preferably 0.08 or less, even more preferably 0.06 or less, and particularly preferably 0.03 or less.

[0033] When an adhesive layer is disposed between optically anisotropic layers each having a liquid crystal compound fixed therein, a highly refractive adhesive or pressure sensitive adhesive may be used. To increase the refractive index, it is also preferable to use a highly refractive monomer or highly refractive metal fine particles. The highly refractive monomer preferably has a benzene ring skeleton in the molecule. Examples of monofunctional monomers having a benzene ring skeleton in the molecule include ethoxylated O-phenylphenol (meth)acrylate, O-phenylphenol glycidyl ether (meth)acrylate, para-cumylphenoxyethylene glycol (meth)acrylate, 2-methacryloyloxyethyl phthalate, 2-acryloyloxyethyl phthalate, 2-acryloyloxyethyl-2-hydroxyethyl phthalate, 2-acryloyloxypropyl phthalate, phenoxyethyl (meth)acrylate, EO-modified phenol (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, EO-modified nonylphenol (meth)acrylate, PO-modified nonylphenol (meth)acrylate, phenyl glycidyl ether (meth)acrylate, neopentyl glycol benzoate (meth)acrylate, nonylphenoxy polyethylene glycol (meth)acrylate, ECH-modified phenoxy (meth)acrylate, benzyl (meth)acrylate, and vinyl carbazole. Examples of highly refractive metal fine particles include inorganic particles. Components constituting inorganic particles include metal oxides, metal nitrides, metal oxynitrides, and simple metals. Metal atoms contained in the metal oxides, metal nitrides, metal oxynitrides, and simple metals include titanium atoms, silicon atoms, aluminum atoms, cobalt atoms, and zirconium atoms. Specific examples of inorganic particles include inorganic oxide particles such as alumina particles, alumina hydrate particles, silica particles, zirconia particles, and clay minerals (e.g., smectite). Zirconium oxide particles are preferred in terms of refractive index. The refractive index can be adjusted to a desired 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.

[0034] (Alignment film) The circular polarizer 10 may further include an alignment film, which may be disposed between each of the optically anisotropic layers. As shown in FIG. 1, the circularly polarizing plate 10 preferably does not have an alignment film between the optically anisotropic layers.

[0035] The alignment layer can be formed by means of rubbing an organic compound (preferably a polymer), oblique evaporation of an inorganic compound, formation of a layer with microgrooves, or deposition of an organic compound (e.g., ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearate) by the Langmuir-Blodgett technique (LB film). Furthermore, alignment films are also known that exhibit alignment functions when an electric field is applied, a magnetic field is applied, or light (preferably polarized light) is irradiated. The alignment film is preferably formed by rubbing a polymer. The alignment film may also be a photo-alignment film. The thickness of the alignment film is not particularly limited as long as it can exhibit an alignment function, but 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.

[0036] (substrate) The circularly polarizing plate 10 may further include a substrate. The substrate is preferably a transparent substrate. The transparent substrate means a substrate having 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.

[0037] The substrate may also be made up of multiple laminated sheets. The surface of the substrate may be subjected to a surface treatment (e.g., glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, or flame treatment) to improve adhesion with the layer provided thereon. An adhesive layer (undercoat layer) may also be provided on the substrate. The substrate may be a so-called temporary support. For example, after the optically anisotropic layer is produced on the substrate, the substrate may be peeled off from the optically anisotropic layer, if necessary.

[0038] <Positional relationship between the absorption axis of the circular polarizer and the in-plane slow axis of the optically anisotropic layer> The positional relationship between the absorption axis of the circular polarizer and the in-plane slow axis of the optically anisotropic layer in the circular polarizer of the present invention will be described below. In the circularly polarizing plate of the present invention, the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are parallel to or perpendicular to each other. First, when the circular polarizer is observed from the polarizer side, the absorption axis of the polarizer is set to 90°, and counterclockwise rotation is expressed as a positive angle value, the angle of the in-plane slow axis on the polarizer-side surface of the first optically anisotropic layer is defined as X. When the circular polarizer is observed from the polarizer side, and counterclockwise rotation is expressed as a positive angle value and clockwise rotation is expressed as a negative angle value, the twist angle of the liquid crystal compound in the first optically anisotropic layer is defined as Y. When the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are parallel, X and Y satisfy any of requirements 1 to 4. Requirement 1: 0°≦X<20°, and -X+20°≦Y≦-X+60° Requirement 2: 0°≦X≦20°, and -X-60°≦Y≦-X-20° Requirement 3: 160°≦X≦180°, and -X+200°≦Y≦-X+240° Requirement 4: 160° <X≦180°、および、-X+120°≦Y≦-X+160° Furthermore, in terms of the superior effects of the present invention, any one of requirements 1-1 to 4-1 is satisfied. Requirement 1-1: 0°≦X<20°, and -X+30°≦Y≦-X+50° Requirement 2-1: 0°≦X≦20°, and -X-50°≦Y≦-X-30° Requirement 3-1: 160°≦X≦180°, and -X+210°≦Y≦-X+230° Requirement 4-1: 160° <X≦180°、および、-X+130°≦Y≦-X+150° Requirements 1 to 4 are explained below.

[0039] (Requirement 1) Requirement 1 satisfies the relationship between the following two equations. Formula (A-1) 0°≦X<20° Formula (A-2) -X+20°≦Y≦-X+60° That is, this means that X is in the range of 0° or more and less than 20°, and Y is in the range of −X+20° to −X+60°. Hereinafter, one embodiment of a circularly polarizing plate that satisfies the above requirement 1 will be described with reference to the drawings. Fig. 2 is a diagram showing the relationship between the absorption axis of the polarizer 12 and the in-plane slow axes of the first optically anisotropic layer 14A and the second optically anisotropic layer 16A in the circular polarizing plate 10A. Note that the arrow in the polarizer 12 in Fig. 2 represents the absorption axis, and the arrows in the first optically anisotropic layer 14A and the second optically anisotropic layer 16A represent the in-plane slow axes in the respective layers. FIG. 3 shows the relationship between the angle between the absorption axis (thick line) of the polarizer 12 and the in-plane slow axes (solid lines) of the first optically anisotropic layer 14A and the second optically anisotropic layer 16A when observed from the white arrow in FIG. The angle of the in-plane slow axis, when observed from the white arrow in Fig. 2, is expressed as a positive angle value counterclockwise with the absorption axis of polarizer 12 being 90°. The twist angle of the liquid crystal compound, when observed from the white arrow in Fig. 2, is determined as a right twist (clockwise) or left twist (counterclockwise) based on the in-plane slow axis on surface 141A on the front side (polarizer 12 side) of first optically anisotropic layer 14A, and a counterclockwise angle is expressed as a positive angle value, and a clockwise angle is expressed as a negative angle value.

[0040] As shown in FIG. 2, the circularly polarizing plate 10A includes a polarizer 12, a first optically anisotropic layer 14A, and a second optically anisotropic layer 16A in this order. 2 and 3, when the absorption axis of the polarizer 12 is set to 90°, the in-plane slow axis of the surface 141A of the first optically anisotropic layer 14A facing the polarizer 12 is 10°. More specifically, the in-plane slow axis of the surface 141A of the first optically anisotropic layer 14A facing the polarizer 12 is rotated by 10° (10° counterclockwise) with respect to the direction (dashed line in FIG. 3) perpendicular to the absorption axis of the polarizer 12. In other words, the angle φa1 formed by the direction perpendicular to the absorption axis of the polarizer 12 and the in-plane slow axis of the surface 141A of the first optically anisotropic layer 14A facing the polarizer 12 is 10°. Although Figures 2 and 3 show an embodiment in which the in-plane slow axis on surface 141A of first optically anisotropic layer 14A is at a position of 10°, the present invention is not limited to this embodiment, and it is sufficient that the relationship of formula (A-1) is satisfied, specifically, it is sufficient that the angle is within the range of 0° or more and less than 20°.

[0041] As described above, the first optically anisotropic layer 14A is a layer in which a liquid crystal compound is fixed and twisted along a helical axis extending in the thickness direction. Therefore, the in-plane slow axis of the first optically anisotropic layer 14A on the polarizer 12 side of the surface 141A forms a predetermined twist angle with the in-plane slow axis of the first optically anisotropic layer 14A on the surface 142A opposite the polarizer 12 side of the first optically anisotropic layer 14A. Specifically, as shown in FIGS. 2 and 3, the angle φa2 formed by the in-plane slow axis of the first optically anisotropic layer 14A on the polarizer 12 side of the surface 141A and the in-plane slow axis of the first optically anisotropic layer 14A on the surface 142A opposite the polarizer 12 side of the first optically anisotropic layer 14A is 30°. More specifically, the twist direction of the liquid crystal compound in the first optically anisotropic layer 14A is left-handed (counterclockwise), and the twist angle is 30°. 2 and 3, the twist direction of the liquid crystal compound in the first optically anisotropic layer 14A is left-handed (counterclockwise) and the twist angle is 30°, but the present invention is not limited to this and may be any other suitable structure as long as it satisfies the relationship of formula (A-2), specifically, within the range of -X+20° to -X+60°. More specifically, when X is 10° as described above, Y may be within the range of 10 to 50°.

[0042] As shown in FIGS. 2 and 3, the absorption axis of the polarizer 12 is parallel to the in-plane slow axis of the surface 161A of the second optically anisotropic layer 16A on the polarizer 12 side. The second optically anisotropic layer 16A is an A plate, and the in-plane slow axis on the surface 161A of the second optically anisotropic layer 16A facing the polarizer 12 is parallel to the in-plane slow axis on the surface 162A of the second optically anisotropic layer 16A opposite the polarizer 12 side.

[0043] (Requirement 2) Requirement 2 satisfies the relationship between the following two equations. Formula (B-1) 0°≦X≦20° Formula (B-2) -X-60°≦Y≦-X-20° That is, X is in the range of 0 to 20 degrees, and Y is in the range of -X-60 degrees to -X-20 degrees. An embodiment of a circularly polarizing plate that satisfies the above requirement 2 will be described below with reference to the drawings. Fig. 4 is a diagram showing the relationship between the absorption axis of the polarizer 12 and the in-plane slow axes of the first optically anisotropic layer 14B and the second optically anisotropic layer 16B in the circular polarizing plate 10B. Note that the arrow in the polarizer 12 in Fig. 4 represents the absorption axis, and the arrows in the first optically anisotropic layer 14B and the second optically anisotropic layer 16B represent the in-plane slow axes in the respective layers. FIG. 5 shows the relationship between the angle between the absorption axis (thick line) of the polarizer 12 and the in-plane slow axes (solid lines) of the first optically anisotropic layer 14B and the second optically anisotropic layer 16B when observed from the white arrow in FIG. The angle of the in-plane slow axis, when observed from the white arrow in Fig. 4, is expressed as a positive angle value counterclockwise with the absorption axis of polarizer 12 being 90°. The twist angle of the liquid crystal compound, when observed from the white arrow in Fig. 4, is determined as a right twist (clockwise) or left twist (counterclockwise) based on the in-plane slow axis on surface 141B on the front side (polarizer 12 side) of first optically anisotropic layer 14B, and a counterclockwise angle is expressed as a positive angle value, and a clockwise angle is expressed as a negative angle value.

[0044] As shown in FIG. 4, the circularly polarizing plate 10B includes a polarizer 12, a first optically anisotropic layer 14B, and a second optically anisotropic layer 16B in this order. 4 and 5, when the absorption axis of the polarizer 12 is set to 90°, the in-plane slow axis of the surface 141B of the first optically anisotropic layer 14A facing the polarizer 12 is 10°. More specifically, the in-plane slow axis of the surface 141B of the first optically anisotropic layer 14B facing the polarizer 12 is rotated by 10° (10° counterclockwise) with respect to the direction (dashed line in FIG. 5) perpendicular to the absorption axis of the polarizer 12. In other words, the angle φb1 formed by the direction perpendicular to the absorption axis of the polarizer 12 and the in-plane slow axis of the surface 141B of the first optically anisotropic layer 14B facing the polarizer 12 is 10°. Although Figures 4 and 5 show an embodiment in which the in-plane slow axis on surface 141B of first optically anisotropic layer 14B is at a position of 10°, the present invention is not limited to this embodiment, and it is sufficient that the relationship of formula (B-1) is satisfied, specifically, it is sufficient that the angle is within the range of 0 to 20°.

[0045] As described above, the first optically anisotropic layer 14B is a layer in which a liquid crystal compound is fixed and twisted along a helical axis extending in the thickness direction. Therefore, the in-plane slow axis of the first optically anisotropic layer 14B on the polarizer 12 side, the surface 141B, and the in-plane slow axis of the first optically anisotropic layer 14B on the opposite side from the polarizer 12 form a predetermined twist angle. Specifically, as shown in FIGS. 4 and 5, the angle φb2 formed by the in-plane slow axis of the first optically anisotropic layer 14B on the polarizer 12 side, the surface 141B, and the in-plane slow axis of the first optically anisotropic layer 14B on the opposite side from the polarizer 12, the surface 142B, is 50°. More specifically, the twist direction of the liquid crystal compound in the first optically anisotropic layer 14B is right-handed (clockwise), and the twist angle is −50°. 4 and 5, the twist direction of the liquid crystal compound in the first optically anisotropic layer 14B is right-handed (clockwise) and the twist angle is -50°, but the present invention is not limited to this and may be any other suitable structure as long as it satisfies the relationship of formula (B-2), specifically, within the range of -X-60° to -X-20°. More specifically, when X is 10° as described above, Y may be within the range of -70° to -30°.

[0046] As shown in FIGS. 4 and 5, the absorption axis of the polarizer 12 is parallel to the in-plane slow axis of the surface 161B of the second optically anisotropic layer 16B on the polarizer 12 side. The second optically anisotropic layer 16B is an A plate, and the in-plane slow axis at the surface 161B of the second optically anisotropic layer 16B facing the polarizer 12 is parallel to the in-plane slow axis at the surface 162B of the second optically anisotropic layer 16B opposite the polarizer 12 side.

[0047] (Requirement 3) Requirement 3 satisfies the relationship between the following two equations. Formula (C-1) 160°≦X≦180° Formula (C-2) -X+200°≦Y≦-X+240° That is, this means that X is in the range of 160 to 180 degrees, and Y is in the range of -X+200 degrees to -X+240 degrees. An embodiment of a circularly polarizing plate that satisfies the above requirement 3 will be described below with reference to the drawings. Fig. 6 is a diagram showing the relationship between the absorption axis of the polarizer 12 and the in-plane slow axes of the first optically anisotropic layer 14C and the second optically anisotropic layer 16C in a circular polarizing plate 10C. Note that the arrow in the polarizer 12 in Fig. 6 represents the absorption axis, and the arrows in the first optically anisotropic layer 14C and the second optically anisotropic layer 16C represent the in-plane slow axes in the respective layers. FIG. 7 shows the relationship between the angle between the absorption axis (thick line) of the polarizer 12 and the in-plane slow axes (solid lines) of the first optically anisotropic layer 14C and the second optically anisotropic layer 16C when observed from the white arrow in FIG. When observed from the white arrow in Fig. 6, the angle of the in-plane slow axis is expressed as a positive angle value, with the absorption axis of polarizer 12 being 90°. When observed from the white arrow in Fig. 6, the twist angle of the liquid crystal compound is determined as a right twist (clockwise) or left twist (counterclockwise) based on the in-plane slow axis on surface 141C on the front side (polarizer 12 side) of first optically anisotropic layer 14C, and a counterclockwise twist is expressed as a positive angle value, and a clockwise twist is expressed as a negative angle value.

[0048] As shown in FIG. 6, the circularly polarizing plate 10C includes a polarizer 12, a first optically anisotropic layer 14C, and a second optically anisotropic layer 16C in this order. 6 and 7, when the absorption axis of the polarizer 12 is set to 90°, the in-plane slow axis of the surface 141C of the first optically anisotropic layer 14C facing the polarizer 12 is 170°. More specifically, the in-plane slow axis of the surface 141C of the first optically anisotropic layer 14C facing the polarizer 12 is rotated by 170° (170° counterclockwise) with respect to the direction (dashed line in FIG. 7) perpendicular to the absorption axis of the polarizer 12. In other words, the angle φc1 formed by the direction perpendicular to the absorption axis of the polarizer 12 and the in-plane slow axis of the surface 141C of the first optically anisotropic layer 14C facing the polarizer 12 is 170°. Although Figures 6 and 7 show an embodiment in which the in-plane slow axis on the surface 141C of the first optically anisotropic layer 14C is at a position of 170°, the present invention is not limited to this embodiment, and it is sufficient that the relationship of formula (C-1) is satisfied, specifically, it is sufficient that the angle is within the range of 160 to 180°.

[0049] As described above, the first optically anisotropic layer 14C is a layer in which a liquid crystal compound is fixed and twisted along a helical axis extending in the thickness direction. Therefore, the in-plane slow axis of the first optically anisotropic layer 14C on the polarizer 12 side and the in-plane slow axis of the first optically anisotropic layer 14C on the opposite side from the polarizer 12 form a predetermined twist angle. Specifically, as shown in FIGS. 6 and 7, the angle φc2 formed by the in-plane slow axis of the first optically anisotropic layer 14C on the polarizer 12 side and the in-plane slow axis of the first optically anisotropic layer 14C on the opposite side from the polarizer 12 is 50°. More specifically, the twist direction of the liquid crystal compound in the first optically anisotropic layer 14C is left-handed (counterclockwise), and the twist angle is 50°. 6 and 7, the twist direction of the liquid crystal compound in the first optically anisotropic layer 14C is left-handed (counterclockwise) and the twist angle is 50°, but the present invention is not limited to this and may be any other suitable structure as long as it satisfies the relationship of formula (C-2), specifically, within the range of -X+200° to -X+240°. More specifically, when X is 170° as described above, Y may be within the range of 30 to 70°.

[0050] As shown in FIGS. 6 and 7, the absorption axis of the polarizer 12 is parallel to the in-plane slow axis of the surface 161C of the second optically anisotropic layer 16C facing the polarizer 12. The second optically anisotropic layer 16C is an A plate, and the in-plane slow axis at the surface 161C of the second optically anisotropic layer 16C facing the polarizer 12 is parallel to the in-plane slow axis at the surface 162C of the second optically anisotropic layer 16C opposite the polarizer 12 side.

[0051] (Requirement 4) Requirement 4 satisfies the relationship between the following two equations. Formula (D-1) 160° <X≦180° Formula (D-2) -X+120°≦Y≦-X+160° That is, this means that X is in the range of more than 160° and not more than 180°, and Y is in the range of −X+120° to −X+160°. An embodiment of a circularly polarizing plate that satisfies the above requirement 4 will now be described with reference to the drawings. Fig. 8 is a diagram showing the relationship between the absorption axis of the polarizer 12 and the in-plane slow axes of the first optically anisotropic layer 14D and the second optically anisotropic layer 16D in a circular polarizing plate 10D. Note that the arrow in the polarizer 12 in Fig. 8 represents the absorption axis, and the arrows in the first optically anisotropic layer 14D and the second optically anisotropic layer 16D represent the in-plane slow axes in the respective layers. FIG. 9 shows the relationship between the angle between the absorption axis (thick line) of the polarizer 12 and the in-plane slow axes (solid lines) of the first optically anisotropic layer 14D and the second optically anisotropic layer 16D when observed from the white arrow in FIG. When observed from the white arrow in Fig. 8, the angle of the in-plane slow axis is expressed as a positive angle value, with the absorption axis of polarizer 12 being 90°. When observed from the white arrow in Fig. 8, the twist angle of the liquid crystal compound is determined as a right twist (clockwise) or left twist (counterclockwise) based on the in-plane slow axis on surface 141D on the front side (polarizer 12 side) of first optically anisotropic layer 14D, and a counterclockwise twist is expressed as a positive angle value, and a clockwise twist is expressed as a negative angle value.

[0052] As shown in FIG. 8, the circularly polarizing plate 10D includes a polarizer 12, a first optically anisotropic layer 14D, and a second optically anisotropic layer 16D in this order. 8 and 9, when the absorption axis of the polarizer 12 is set to 90°, the in-plane slow axis of the surface 141D of the first optically anisotropic layer 14D facing the polarizer 12 is 170°. More specifically, the in-plane slow axis of the surface 141D of the first optically anisotropic layer 14D facing the polarizer 12 is rotated by 170° (170° counterclockwise) with respect to the direction (dashed line in FIG. 9) perpendicular to the absorption axis of the polarizer 12. In other words, the angle φd1 formed by the direction perpendicular to the absorption axis of the polarizer 12 and the in-plane slow axis of the surface 141D of the first optically anisotropic layer 14D facing the polarizer 12 is 170°. 8 and 9 show an embodiment in which the in-plane slow axis on the surface 141D of the first optically anisotropic layer 14D is at a position of 170°, but the present invention is not limited to this embodiment, and it is sufficient that the relationship of formula (D-1) is satisfied, specifically, it is sufficient that the angle is in the range of more than 160° and not more than 180°.

[0053] As described above, the first optically anisotropic layer 14D is a layer in which a liquid crystal compound is fixed and twisted along a helical axis extending in the thickness direction. Therefore, the in-plane slow axis of the first optically anisotropic layer 14D on the polarizer 12 side of the surface 141D and the in-plane slow axis of the first optically anisotropic layer 14D on the opposite side of the polarizer 12 form a predetermined twist angle. Specifically, as shown in FIGS. 8 and 9, the angle φd2 formed by the in-plane slow axis of the first optically anisotropic layer 14D on the polarizer 12 side of the surface 141D and the in-plane slow axis of the first optically anisotropic layer 14D on the opposite side of the polarizer 12 is 30°. More specifically, the twist direction of the liquid crystal compound in the first optically anisotropic layer 14D is right-handed (clockwise), and the twist angle is −30°. 8 and 9, the twist direction of the liquid crystal compound in the first optically anisotropic layer 14D is right-handed (clockwise) and the twist angle is -30°, but the present invention is not limited to this and may be any other suitable structure as long as it satisfies the relationship of formula (D-2), specifically, within the range of -X+120° to -X+160°. More specifically, when X is 170° as described above, Y may be within the range of -50 to -10°.

[0054] As shown in FIGS. 8 and 9, the absorption axis of the polarizer 12 is parallel to the in-plane slow axis of the surface 161D of the second optically anisotropic layer 16D on the polarizer 12 side. The second optically anisotropic layer 16D is an A plate, and the in-plane slow axis at the surface 161D of the second optically anisotropic layer 16D facing the polarizer 12 is parallel to the in-plane slow axis at the surface 162D of the second optically anisotropic layer 16D opposite the polarizer 12 side.

[0055] Furthermore, when the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are perpendicular to each other, X and Y satisfy requirement 5 or 6. Requirement 5: 70°≦X<110°, and -X+110°≦Y≦-X+150° Requirement 6: 70° <X≦110°、および、-X+30°≦Y≦-X+70° Among these, it is more preferable to satisfy requirement 5-1 or 6-1 in terms of obtaining better effects of the present invention. Requirement 5-1: 70°≦X<110°, and -X+120°≦Y≦-X+140° Requirement 6-1: 70° <X≦110°、および、-X+40°≦Y≦-X+60° Requirements 5 and 6 are explained below.

[0056] (Requirement 5) Requirement 5 satisfies the relationship between the following two equations. Formula (E-1) 70°≦X<110° Formula (E-2) -X+110°≦Y≦-X+150° That is, this means that X is in the range of 70° or more and less than 110°, and Y is in the range of −X+110° to −X+150°. An embodiment of a circularly polarizing plate that satisfies the above requirement 5 will be described below with reference to the drawings. Fig. 10 is a diagram showing the relationship between the absorption axis of the polarizer 12 and the in-plane slow axes of the first optically anisotropic layer 14E and the second optically anisotropic layer 16E in a circular polarizing plate 10E. Note that the arrow in the polarizer 12 in Fig. 10 represents the absorption axis, and the arrows in the first optically anisotropic layer 14E and the second optically anisotropic layer 16E represent the in-plane slow axes in the respective layers. FIG. 11 shows the relationship between the angle between the absorption axis (thick line) of the polarizer 12 and the in-plane slow axes (solid lines) of the first optically anisotropic layer 14E and the second optically anisotropic layer 16E when observed from the white arrow in FIG. 10. When observed from the white arrow in Fig. 10, the angle of the in-plane slow axis is expressed as a positive angle value, with the absorption axis of polarizer 12 being 90°. When observed from the white arrow in Fig. 10, the twist angle of the liquid crystal compound is determined as a right twist (clockwise) or left twist (counterclockwise) based on the in-plane slow axis on surface 141E on the front side (polarizer 12 side) of first optically anisotropic layer 14E, and a counterclockwise twist is expressed as a positive angle value, and a clockwise twist is expressed as a negative angle value.

[0057] As shown in FIG. 10, the circularly polarizing plate 10E includes a polarizer 12, a first optically anisotropic layer 14E, and a second optically anisotropic layer 16E in this order. 10 and 11, when the absorption axis of the polarizer 12 is set to 90°, the in-plane slow axis of the surface 141E of the first optically anisotropic layer 14E facing the polarizer 12 is 90°. More specifically, the in-plane slow axis of the surface 141E of the first optically anisotropic layer 14E facing the polarizer 12 is rotated by 90° (90° counterclockwise) with respect to the direction (dashed line in FIG. 11) perpendicular to the absorption axis of the polarizer 12. In other words, the angle φe1 formed by the direction perpendicular to the absorption axis of the polarizer 12 and the in-plane slow axis of the surface 141E of the first optically anisotropic layer 14E facing the polarizer 12 is 90°. 10 and 11 show an embodiment in which the in-plane slow axis at the surface 141E of the first optically anisotropic layer 14E is at a position of 90°, but the present invention is not limited to this embodiment as long as it satisfies the relationship of formula (E-1), specifically, it is sufficient if it is within the range of 70° or more and less than 110°.

[0058] As described above, the first optically anisotropic layer 14E is a layer in which a liquid crystal compound is fixed and twisted along a helical axis extending in the thickness direction. Therefore, the in-plane slow axis of the first optically anisotropic layer 14E on the polarizer 12 side forms a predetermined twist angle with the in-plane slow axis of the first optically anisotropic layer 14E on the surface 141E opposite the polarizer 12 side. Specifically, as shown in FIGS. 10 and 11, the angle φe2 formed by the in-plane slow axis of the first optically anisotropic layer 14E on the polarizer 12 side and the in-plane slow axis of the first optically anisotropic layer 14E on the surface 142E opposite the polarizer 12 side is 40°. More specifically, the twist direction of the liquid crystal compound in the first optically anisotropic layer 14E is left-handed (counterclockwise), and the twist angle is 40°. 10 and 11 show an embodiment in which the twist direction of the liquid crystal compound in the first optically anisotropic layer 14E is left-handed (counterclockwise) and the twist angle is 40°, but the present invention is not limited to this embodiment and may be any other embodiment as long as it satisfies the relationship of formula (E-2), specifically, within the range of -X+110° to -X+150°. More specifically, when X is 90° as described above, Y may be within the range of 20 to 60°.

[0059] As shown in FIGS. 10 and 11, the absorption axis of the polarizer 12 and the in-plane slow axis of the surface 161E of the second optically anisotropic layer 16E facing the polarizer 12 are perpendicular to each other. The second optically anisotropic layer 16E is an A plate, and the in-plane slow axis at the surface 161E of the second optically anisotropic layer 16E facing the polarizer 12 is parallel to the in-plane slow axis at the surface 162E of the second optically anisotropic layer 16E opposite the polarizer 12 side.

[0060] (Requirement 6) Requirement 6 satisfies the relationship between the following two equations. Formula (F-1) 70° <X≦110° Formula (F-2) -X+30°≦Y≦-X+70° That is, this means that X is in the range of more than 70° and not more than 110°, and Y is in the range of −X+30° to −X+70°. An embodiment of a circularly polarizing plate that satisfies the above requirement 6 will now be described with reference to the drawings. Fig. 12 is a diagram showing the relationship between the absorption axis of the polarizer 12 and the in-plane slow axes of the first optically anisotropic layer 14F and the second optically anisotropic layer 16F in a circular polarizing plate 10F. Note that the arrow in the polarizer 12 in Fig. 12 represents the absorption axis, and the arrows in the first optically anisotropic layer 14F and the second optically anisotropic layer 16F represent the in-plane slow axes in the respective layers. Figure 13 shows the relationship between the angle between the absorption axis (thick line) of the polarizer 12 and the in-plane slow axes (solid lines) of the first optically anisotropic layer 14F and the second optically anisotropic layer 16F when observed from the white arrow in Figure 12. When observed from the white arrow in Fig. 12, the angle of the in-plane slow axis is expressed as a positive angle value, with the absorption axis of polarizer 12 being 90°. When observed from the white arrow in Fig. 10, the twist direction of the liquid crystal compound is determined as a right twist (clockwise) or left twist (counterclockwise) based on the in-plane slow axis on surface 141F on the front side (polarizer 12 side) of first optically anisotropic layer 14F, and a counterclockwise direction is expressed as a positive angle value, and a clockwise direction is expressed as a negative angle value.

[0061] As shown in FIG. 12, the circular polarizing plate 10F includes a polarizer 12, a first optically anisotropic layer 14F, and a second optically anisotropic layer 16F in this order. 12 and 13, when the absorption axis of the polarizer 12 is set to 90°, the in-plane slow axis of the surface 141F of the first optically anisotropic layer 14F facing the polarizer 12 is 90°. More specifically, the in-plane slow axis of the surface 141F of the first optically anisotropic layer 14F facing the polarizer 12 is rotated by 90° (90° counterclockwise) with respect to the direction (dashed line in FIG. 13) perpendicular to the absorption axis of the polarizer 12. In other words, the angle φf1 formed between the direction perpendicular to the absorption axis of the polarizer 12 and the in-plane slow axis of the surface 141F of the first optically anisotropic layer 14F facing the polarizer 12 is 90°. 12 and 13 show an embodiment in which the in-plane slow axis on the surface 141F of the first optically anisotropic layer 14F is at a position of 90°, but the present invention is not limited to this embodiment, and it is sufficient that the relationship of formula (F-1) is satisfied, specifically, it is sufficient that the angle is in the range of more than 70° and not more than 110°.

[0062] As described above, the first optically anisotropic layer 14F is a layer in which a liquid crystal compound is fixed and twisted along a helical axis extending in the thickness direction. Therefore, the in-plane slow axis of the surface 141F of the first optically anisotropic layer 14F facing the polarizer 12 forms a predetermined twist angle with the in-plane slow axis of the surface 142F of the first optically anisotropic layer 14F opposite the polarizer 12 side. Specifically, as shown in Figures 12 and 13, the angle φf2 formed by the in-plane slow axis of the surface 141F of the first optically anisotropic layer 14F facing the polarizer 12 and the in-plane slow axis of the surface 142F of the first optically anisotropic layer 14F opposite the polarizer 12 side is -40°. More specifically, the twist direction of the liquid crystal compound in the first optically anisotropic layer 14F is right-handed (clockwise), and the twist angle is −40°. 12 and 13, the twist direction of the liquid crystal compound in the first optically anisotropic layer 14F is right-handed (clockwise) and the twist angle is -40°, but the present invention is not limited to this and may be any other suitable structure as long as it satisfies the relationship of formula (F-2), specifically, within the range of -X+30° to -X+70°. More specifically, when X is 90° as described above, Y may be within the range of -60° to -20°.

[0063] As shown in FIGS. 12 and 13, the absorption axis of the polarizer 12 and the in-plane slow axis of the surface 161F of the second optically anisotropic layer 16F facing the polarizer 12 are perpendicular to each other. The second optically anisotropic layer 16F is an A plate, and the in-plane slow axis at the surface 161F of the second optically anisotropic layer 16F facing the polarizer 12 is parallel to the in-plane slow axis at the surface 162F of the second optically anisotropic layer 16F opposite the polarizer 12 side.

[0064] (Manufacturing method of circularly polarizing plate) The method for producing the circularly polarizing plate is not particularly limited, and any known method can be used. For example, a circularly polarizing plate can be produced by separately preparing a polarizer, a first optically anisotropic layer, and a second optically anisotropic layer, and then bonding them together in a predetermined order via an adhesive layer (e.g., a pressure-sensitive adhesive layer or an adhesive layer). The first and second optically anisotropic layers can be produced using compositions for forming optically anisotropic layers, each of which contains a liquid crystal compound having a polymerizable group.

[0065] Hereinafter, a method for producing optically anisotropic layers (first optically anisotropic layer to second optically anisotropic layer) using a composition for forming an optically anisotropic layer containing a liquid crystal compound having a polymerizable group will be described in detail.

[0066] The liquid crystal compound having a polymerizable group (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, a rod-shaped liquid crystal compound or a discotic liquid crystal compound is appropriately selected depending on the properties of the optically anisotropic layer to be formed. The content of the polymerizable liquid crystal compound in the composition for forming an optically anisotropic layer is preferably from 60 to 99 mass %, more preferably from 70 to 98 mass %, based on the total solid content of the composition for forming an optically anisotropic layer. The solid content means a component capable of forming an optically anisotropic layer from which the solvent has been removed, and is considered to be a solid content even if the component is in a liquid state.

[0067] The composition for forming an optically anisotropic layer may contain compounds other than the liquid crystal compound having a polymerizable group. For example, the optically anisotropic layer-forming composition for forming the first optically anisotropic layer 14 preferably contains a chiral agent to cause the liquid crystal compound to undergo twisted alignment. The chiral agent is added to cause the liquid crystal compound to undergo twisted alignment, but of course, if the liquid crystal compound is an optically active compound, such as one having an asymmetric carbon atom in the molecule, the addition of a chiral agent is not necessary. Furthermore, depending on the production method and twist angle, the addition of a chiral agent may not be necessary. The chiral agent is not particularly limited in structure 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 the chiral agent used is not particularly limited, and is adjusted so as to achieve the above-mentioned twist angle.

[0068] The composition for forming an optically anisotropic layer may contain a polymerization initiator. The polymerization initiator to be used is selected depending on the type of polymerization reaction, and examples thereof include a thermal polymerization initiator and a photopolymerization initiator. The content of the polymerization initiator in the composition for forming an optically anisotropic layer is preferably from 0.01 to 20% by mass, more preferably from 0.5 to 10% by mass, based on the total solid content of the composition for forming an optically anisotropic layer.

[0069] Other components that may be contained in the composition for forming an optically anisotropic layer include, in addition to those mentioned above, polyfunctional monomers, alignment control agents (vertical alignment agents, horizontal alignment agents), surfactants, adhesion improvers, plasticizers, and solvents.

[0070] Examples of methods for applying the composition for forming an optically anisotropic layer include curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, blade coating, gravure coating, and wire bar coating.

[0071] Next, the formed coating film is subjected to an alignment treatment to align the polymerizable liquid crystal compound in the coating film. The alignment treatment can be carried out by drying the coating film at room temperature or by heating the coating film. In the case of a thermotropic liquid crystal compound, the liquid crystal phase formed by the alignment treatment can generally be transitioned by a change in temperature or pressure. In the case of a lyotropic liquid crystal compound, the transition can also be achieved by changing the composition ratio, such as the amount of solvent. The conditions for heating the coating are not particularly limited, but the heating temperature is preferably 50 to 250° C., more preferably 50 to 150° C., and the heating time is preferably 10 seconds to 10 minutes. After heating the coating film, the coating film may be cooled, if necessary, before the curing treatment (light irradiation treatment) described below.

[0072] Next, the coating film in which the polymerizable liquid crystal compound is aligned is subjected to a curing treatment. The method of curing the coating film in which the polymerizable liquid crystal compound is oriented is not particularly limited, and examples thereof include light irradiation treatment and heat treatment. Among these, from the viewpoint of manufacturability, light irradiation treatment is preferred, and ultraviolet irradiation treatment is more preferred. The irradiation conditions for the light irradiation treatment are not particularly limited, but are preferably 50 to 1000 mJ / cm 2 The irradiation dose is preferably 1000 ppm or more. The atmosphere during the light irradiation treatment is not particularly limited, but a nitrogen atmosphere is preferred.

[0073] <Application> The circular polarizing plate of the present invention is an optical element that converts unpolarized light into circularly polarized light. The circularly polarizing plate of the present invention is suitable for use in anti-reflection applications in displays such as liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescent displays (ELDs), and cathode ray tube displays (CRTs).

[0074] <Display device> The circularly polarizing plate of the present invention can be suitably applied to display devices. The display device of the present invention includes a display element and the above-described circular polarizer. The circular polarizer is disposed on the viewing side of the display element, and the polarizer in the circular polarizer is disposed on the viewing side. The display element is not particularly limited, and examples thereof include an organic electroluminescence display element and a liquid crystal display element. [Example]

[0075] The features of the present invention will be explained in more detail below with reference to examples and comparative examples. The materials, amounts used, ratios, treatment details, and treatment procedures shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[0076] Example 1 (1) Preparation of the first optically anisotropic layer (Preparation of Cellulose Ester Solution A-1) The following components were placed in a mixing tank and stirred under heating to prepare a cellulose ester solution A-1.

[0077] Composition of Cellulose Ester Solution A-1 ---------------------------------------------------------------------------------- Cellulose acetate (acetylation degree 2.86) 100 parts by mass Methylene chloride (first solvent) 320 parts by mass Methanol (second solvent) 83 parts by weight 1-butanol (third solvent) 3 parts by mass Triphenyl phosphate 7.6 parts by mass Biphenyl diphenyl phosphate 3.8 parts by mass ----------------------------------------------------------------------------------

[0078] (Preparation of Matting Agent Dispersion B-1) The following components were placed in a disperser and stirred to prepare matting agent dispersion B-1.

[0079] Composition of Matting Agent Dispersion B-1 ---------------------------------------------------------------------------------- Silica particle dispersion (average particle size 16nm) "AEROSIL R972", manufactured by Nippon Aerosil Co., Ltd. 10.0 parts by mass Methylene chloride 72.8 parts by mass Methanol 3.9 parts by mass Butanol 0.5 parts by mass Cellulose ester solution A-1 10.3 parts by mass ----------------------------------------------------------------------------------

[0080] (Preparation of UV absorber solution C-1) The following components were placed in a separate mixing tank and stirred while heating to prepare an ultraviolet absorber solution C-1.

[0081] Composition of UV absorber solution C-1 ---------------------------------------------------------------------------------- Ultraviolet absorber (UV-1 below) 10.0 parts by mass Ultraviolet absorber (UV-2 below) 10.0 parts by mass Methylene chloride 55.7 parts by mass Methanol 10 parts by mass Butanol 1.3 parts by mass Cellulose ester solution A-1 12.9 parts by mass ----------------------------------------------------------------------------------

[0082] [ka]

[0083] (Preparation of Cellulose Ester Film) To a mixture of cellulose ester solution A-1 (94.6 parts by mass) and matting agent dispersion B-1 (1.3 parts by mass), ultraviolet absorber solution C-1 was added so that the ultraviolet absorber (UV-1) and ultraviolet absorber (UV-2) were each 1.0 part by mass per 100 parts by mass of cellulose acylate, and the mixture was heated and stirred to dissolve each component, thereby preparing a dope. The obtained dope was heated to 30°C and cast onto a mirror-finished stainless steel support, which was a drum with a diameter of 3 m, through a casting giesser. The surface temperature of the mirror-finished stainless steel support was set to -5°C, and the coating width was 1470 mm. The cast dope film was blown onto the drum with 150 m of dry air at 34°C. 3The film was dried by applying a sieve at 1 / min, and peeled off from the drum when the residual solvent was 150%. During peeling, the film was stretched by 15% in the transport direction (longitudinal direction). Thereafter, the film was transported while being held at both ends in the width direction (direction perpendicular to the casting direction) with pin tenters (the pin tenter shown in FIG. 3 of JP-A-4-001009), and no stretching treatment was performed in the width direction. The obtained film was further dried by transporting it between the rolls of a heat treatment device, thereby producing a cellulose acylate film (T1). The produced long cellulose acylate film (T1) had a residual solvent content of 0.2% by mass, a thickness of 60 μm, and Re (in-plane retardation) and Rth (thickness direction retardation) at a wavelength of 550 nm of 0.8 nm and 40 nm, respectively.

[0084] (Alkaline saponification treatment) The cellulose acylate film (T1) was passed through a dielectric heating roll at a temperature of 60°C to raise the film surface temperature to 40°C, and then an alkaline solution having the composition shown below was applied to the band surface of the film using a bar coater in an amount of 14 ml / m 2 The resulting film was then transported for 10 seconds under a steam-type far-infrared heater manufactured by Noritake Co., Ltd. that had been heated to 110°C. Subsequently, using the same bar coater, pure water was applied to the resulting film at a rate of 3 ml / m. 2 The obtained film was then washed with water using a fountain coater and then drained with an air knife three times, and then transported to a drying zone at 70°C for 10 seconds to dry, thereby preparing an alkali-saponified cellulose acylate film.

[0085] Alkaline solution composition ──────────────────────────────────── Potassium hydroxide 4.7 parts by mass ·Water 15.8 parts by mass Isopropanol 63.7 parts by weight Surfactant SF-1:C 14 H 29 O(CH2CH2O) 20H 1.0 parts by mass Propylene glycol 14.8 parts by mass ────────────────────────────────────

[0086] (Formation of alignment film) An alignment film coating solution (A) having the following composition was continuously applied to the alkaline saponified surface of the cellulose acylate film (T1) using a wire bar #14. The film with the coating was dried with hot air at 60°C for 60 seconds and then with hot air at 100°C for 120 seconds. The saponification degree of the modified polyvinyl alcohol used was 88%.

[0087] Composition of alignment film coating solution (A) ---------------------------------------------------------------------------------- 10 parts by weight of the following modified polyvinyl alcohol ·Water 308 parts by mass Methanol 70 parts by weight 29 parts by weight of isopropanol Photopolymerization initiator (Irgacure 2959, manufactured by Ciba Japan) 0.8 parts by mass ----------------------------------------------------------------------------------

[0088] [ka]

[0089] (Formation of First Optically Anisotropic Layer) The alignment film thus prepared was subjected to continuous rubbing treatment. At this time, the longitudinal direction of the long film was parallel to the conveying direction, and the angle between the longitudinal direction of the film (conveying direction) and the rotation axis of the rubbing roller was 40° (the longitudinal direction of the film (conveying direction) was set to 90°, and when observed from the alignment film side, the film width direction was set as the reference (0°), and if the counterclockwise direction is expressed as a positive value, the rotation axis of the rubbing roller was at -50°. In other words, the position of the rotation axis of the rubbing roller corresponded to a position rotated 40° counterclockwise with the longitudinal direction of the film as the reference).

[0090] An optically anisotropic layer-forming composition (A) containing the following rod-like liquid crystal compound was applied to the above-mentioned rubbed film using a Giesser coater to form a composition layer. Next, the obtained composition layer was heated at 100°C for 80 seconds, and then irradiated with ultraviolet light (irradiation dose: 500 mJ / cm) using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at 57°C under a nitrogen atmosphere. 2 ), a first optically anisotropic layer in which the alignment state of the liquid crystal compound was fixed was formed, thereby producing an optical film (A).

[0091] ---------------------------------------------------------------------------------- Optically anisotropic layer-forming composition (A) ---------------------------------------------------------------------------------- 80 parts by mass of the following rod-shaped liquid crystal compound (A): 3 parts by mass of the following rod-shaped liquid crystal compound (B): 17 parts by mass of the following rod-shaped liquid crystal compound (C): Ethylene oxide modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass Photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan) 3 parts by weight 0.11 parts by mass of the following chiral agent (A): 0.08 parts by mass of the following polymer (A): Methyl isobutyl ketone 117 parts by mass Ethyl propionate 39 parts by mass ----------------------------------------------------------------------------------

[0092] Rod-like liquid crystal compound (A) (hereinafter referred to as a mixture of compounds)

[0093] [ka]

[0094] Rod-shaped liquid crystal compound (B)

[0095] [ka]

[0096] Rod-shaped liquid crystal compound (C)

[0097] [ka]

[0098] Chiral agent (A)

[0099] [ka]

[0100] Polymer (A) (wherein the numerical value for each repeating unit represents the content (% by mass) of each repeating unit relative to all repeating units.)

[0101] [ka]

[0102] The optical properties of the first optically anisotropic layer prepared above were determined using an Axoscan from Axometrics and its analysis software (Multi-Layer Analysis). The product (Δnd) of Δn and thickness d at a wavelength of 550 nm was 347 nm, the twist angle of the liquid crystal compound was 40°, and the alignment axis angle of the liquid crystal compound relative to the width direction of the film was 40° on the alignment film side and 0° on the air side. The alignment axis angle of the liquid crystal compound contained in the first optically anisotropic layer is expressed as negative clockwise (right-handed) and positive counterclockwise (left-handed) when observed from the air side of the first optically anisotropic layer, with the width direction of the film being the reference 0°. The twist angle of the liquid crystal compound is expressed here as negative when the orientation direction of the liquid crystal compound on the film side (rear side) is clockwise (right-handed) and positive when the orientation direction of the liquid crystal compound on the film side (rear side) is counterclockwise (left-handed) when observed from the air side of the first optically anisotropic layer, with the orientation direction of the liquid crystal compound on the air side (front side) as the reference.

[0103] (2) Preparation of the second optically anisotropic layer Following the same procedure as in the above (preparation of the first optically anisotropic layer), an alignment film was formed on a cellulose acylate film (T1), and the alignment film was continuously subjected to a rubbing treatment. At this time, the longitudinal direction of the long film was parallel to the conveying direction, and the angle between the longitudinal direction of the film (conveying direction) and the rotation axis of the rubbing roller was 90° (if the longitudinal direction of the film (conveying direction) is 90° and the counterclockwise direction is expressed as a positive value based on the film width direction when observed from the alignment film side, the rotation axis of the rubbing roller is 0°. In other words, the position of the rotation axis of the rubbing roller corresponds to the position rotated 90° counterclockwise based on the longitudinal direction of the film). An optically anisotropic layer-forming composition (B) containing the following rod-like liquid crystal compound was applied to the above-mentioned rubbed film using a Giesser coater to form a composition layer. Next, the obtained composition layer was heated at 100°C for 80 seconds, and then irradiated with ultraviolet light (irradiation dose: 500 mJ / cm) using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at 57°C under a nitrogen atmosphere. 2), a second optically anisotropic layer (A plate) in which the alignment state of the liquid crystal compound was fixed was formed, and an optical film (B) was produced.

[0104] ---------------------------------------------------------------------------------- Optically anisotropic layer-forming composition (B) ---------------------------------------------------------------------------------- 80 parts by mass of the rod-shaped liquid crystal compound (A) 3 parts by mass of the above rod-shaped liquid crystal compound (B) 17 parts by mass of the rod-shaped liquid crystal compound (C) Ethylene oxide modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass Photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan) 3 parts by weight 0.08 parts by mass of the above polymer (A) Methyl isobutyl ketone 117 parts by mass Ethyl propionate 39 parts by mass ----------------------------------------------------------------------------------

[0105] The optical properties of the second optically anisotropic layer prepared as described above were determined using an Axoscan from Axometrics and its analysis software (Multi-Layer Analysis). The in-plane retardation at a wavelength of 550 nm was 97.5 nm, the twist angle of the liquid crystal compound was 0°, and the alignment axis angle of the liquid crystal compound relative to the longitudinal direction of the film was 90° on both the alignment film side and the air side. The alignment axis angle of the liquid crystal compound contained in the second optically anisotropic layer is expressed as negative for clockwise (right-handed) and positive for counterclockwise (left-handed) when observed from the air side of the second optically anisotropic layer, with the width direction of the film being the reference angle of 0°.

[0106] (3) Preparation of polarizer A polyvinyl alcohol (PVA) film with a thickness of 80 μm was dyed by immersing it in an iodine aqueous solution with an iodine concentration of 0.05% by mass at 30°C for 60 seconds, and then stretched longitudinally to 5 times its original length while immersing it in a boric acid aqueous solution with a boric acid concentration of 4% by mass for 60 seconds.Then, the film was dried at 50°C for 4 minutes to obtain a polarizer with a thickness of 20 μm. A commercially available cellulose acylate film "TD80UL" (manufactured by Fujifilm Corporation) was prepared and immersed in a 1.5 mol / L aqueous solution of sodium hydroxide at 55°C, after which the sodium hydroxide was thoroughly rinsed off with water. The film was then immersed in a 0.005 mol / L aqueous solution of dilute sulfuric acid at 35°C for 1 minute, and then immersed in water to thoroughly rinse off the dilute sulfuric acid. Finally, the sample was thoroughly dried at 120°C to produce a polarizer protective film.

[0107] The polarizer protective film prepared above was attached to one side of the polarizer prepared above using a polyvinyl alcohol-based adhesive to prepare a polarizing plate including a polarizer and a polarizer protective film disposed on one side of the polarizer.

[0108] An adhesive (SK-2057, manufactured by Soken Chemical & Engineering Co., Ltd.) was applied to the polarizer (without the polarizer protective film) side of the prepared polarizing plate to form an adhesive layer, and the prepared optical film (A) having the cellulose acylate film, alignment film, and first optically anisotropic layer was attached so that the adhesive layer and the first optically anisotropic layer were in close contact with each other. Thereafter, the cellulose acylate film and alignment film were peeled off to obtain a laminate. Next, an adhesive (SK-2057, manufactured by Soken Chemical & Engineering Co., Ltd.) was applied to the first optically anisotropic layer in the obtained laminate to form an adhesive layer. Next, the laminate on which the adhesive layer was arranged was bonded to the optical film (B) having the cellulose acylate film, alignment film, and second optically anisotropic layer prepared above so that the adhesive layer and the second optically anisotropic layer were in close contact. Thereafter, the cellulose acylate film and alignment film were peeled off. By the above procedure, a circularly polarizing plate 1 was produced in which a polarizer, a first optically anisotropic layer, and a second optically anisotropic layer were arranged in this order.

[0109] <Example 2> (Formation of First Optically Anisotropic Layer) An alignment film was formed on a cellulose acylate film (T1) and continuously subjected to rubbing treatment according to the same procedure as in Example 1. At this time, the longitudinal direction of the long film was parallel to the conveying direction, and the angle between the longitudinal direction of the film (conveying direction) and the rotation axis of the rubbing roller was 40° (when the longitudinal direction of the film (conveying direction) was 90° and the film width direction as observed from the alignment film side was expressed as a reference (0°) and the counterclockwise direction was expressed as a positive value, the rotation axis of the rubbing roller was at 50°. In other words, the position of the rotation axis of the rubbing roller corresponded to a position rotated 40° clockwise with the longitudinal direction of the film as a reference). An optically anisotropic layer-forming composition (C) containing the following rod-like liquid crystal compound was applied to the above-mentioned rubbed film using a Giesser coater to form a composition layer. Next, the obtained composition layer was heated at 100°C for 80 seconds, and then irradiated with ultraviolet light (irradiation dose: 500 mJ / cm) using a metal halide lamp (manufactured by Eye Graphics Co., Ltd.) at 57°C under a nitrogen atmosphere. 2 ), a first optically anisotropic layer in which the alignment state of the liquid crystal compound was fixed was formed, thereby preparing an optical film (C).

[0110] ---------------------------------------------------------------------------------- Optically anisotropic layer-forming composition (C) ---------------------------------------------------------------------------------- 80 parts by mass of the rod-shaped liquid crystal compound (A) 3 parts by mass of the above rod-shaped liquid crystal compound (B) 17 parts by mass of the rod-shaped liquid crystal compound (C) Ethylene oxide modified trimethylolpropane triacrylate (V#360, manufactured by Osaka Organic Chemical Co., Ltd.) 4 parts by mass Photopolymerization initiator (Irgacure 819, manufactured by Ciba Japan) 3 parts by weight 0.10 parts by mass of the following chiral agent (B): 0.08 parts by mass of the above polymer (A) Methyl isobutyl ketone 117 parts by mass Ethyl propionate 39 parts by mass ----------------------------------------------------------------------------------

[0111] (Chiral agent B)

[0112] [ka]

[0113] The optical properties of the first optically anisotropic layer prepared above were determined using an Axoscan from Axometrics and its analysis software (Multi-Layer Analysis). The product of Δn and thickness d (Δnd) at a wavelength of 550 nm was 347 nm, the twist angle of the liquid crystal compound was -40°, and the alignment axis angle of the liquid crystal compound relative to the width direction of the film was -40° on the alignment film side and 0° on the air side. The alignment axis angle of the liquid crystal compound contained in the first optically anisotropic layer is expressed as negative clockwise (right-handed) and positive counterclockwise (left-handed) when observed from the air side of the first optically anisotropic layer, with the width direction of the film being the reference 0°. The twisted structure of the liquid crystal compound is expressed here as negative when the orientation direction of the liquid crystal compound on the film side (rear side) is clockwise (right-handed) and positive when counterclockwise (left-handed) when observed from the air side of the first optically anisotropic layer, with the orientation direction of the liquid crystal compound on the air side (front side) as the reference.

[0114] Thereafter, the same procedures as in Example 1 were followed to prepare a second optically anisotropic layer and a circularly polarizing plate 2.

[0115] <Examples 3 to 14, 17 to 40, 43 to 52, and Comparative Examples 1 to 6> A circularly polarizing plate was prepared using the same procedure as in Example 1, except that the rubbing angle of the alignment film, the type and amount of chiral agent (A or B) in the first optically anisotropic layer, and the amount of application of the second optically anisotropic layer were adjusted to achieve the desired optical properties.

[0116] <Examples 15, 16, 41, and 42> Circularly polarizing plates were produced in the same manner as in Examples 1, 2, 27 and 28, except that a cycloolefin polymer film (trade name: Arton Film, manufactured by JSR Corporation, Re=95 nm) was used for the second optically anisotropic layer.

[0117] <Evaluation> A Samsung GALAXY S4 equipped with an organic EL panel (organic EL display element) was disassembled, and the touch panel with a circular polarizer was peeled off from the organic EL display device. The circular polarizers produced in the above examples and comparative examples were then attached to the touch panel without allowing air to enter, thereby producing an organic EL display device. The organic EL display device with the circularly polarizing plate prepared above was placed in a sunlight environment and evaluated for color tint in the front direction during black display according to the following criteria. In practice, a grade of B or higher is preferable. A: No visible color change at all. B: Coloring is visible, but very slight. C: Coloring is visible and there is also reflected light.

[0118] The column "Relationship between polarizer and second layer" in the table indicates the relationship between the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer, where "parallel" means that the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are parallel, and "orthogonal" means that the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are perpendicular. The column "Polarizer absorption axis [°]" in the table indicates the position of the polarizer absorption axis when the width direction of the film is taken as the reference angle of 0° and counterclockwise rotation is expressed as a positive angle value. In the table, the column "Material of first layer" indicates the material used to form the first optically anisotropic layer, and "rod-like liquid crystal" indicates a rod-like liquid crystal compound. The column "Δnd of first layer" in the table shows the product Δnd of the refractive index anisotropy Δn of the first optically anisotropic layer at a wavelength of 550 nm and the thickness d of the first optically anisotropic layer. In the table, the column "Material of second layer" indicates the material used to form the second optically anisotropic layer, "rod-like liquid crystal" indicates a rod-like liquid crystal compound, and "COP" indicates a cycloolefin polymer. The column "Re of second layer" in the table indicates the in-plane retardation Re(550) of the second optically anisotropic layer at a wavelength of 550 nm. The column "Polarizer-side axis X [°] of first layer" in the table indicates the angle (°) of the in-plane slow axis on the polarizer-side surface of the first optically anisotropic layer when the circular polarizer is observed from the polarizer side, with the absorption axis of the polarizer being 90°, and counterclockwise represented as a positive angle value and clockwise represented as a negative angle value. The column "Twist angle Y [°] of first layer" in the table indicates the twist angle (°) of the liquid crystal compound in the first optically anisotropic layer. The "Axis of second layer [°]" column in the table indicates the position of the in-plane slow axis of the second optically anisotropic layer, with the width direction of the film being the reference 0° and counterclockwise being represented as a positive angle value. The second optically anisotropic layer in each example was an A plate.

[0119] [Table 1]

[0120] [Table 2]

[0121] [Table 3]

[0122] As shown in the above table, it was confirmed that the desired effects were obtained when the circularly polarizing plate of the present invention was used. Furthermore, it was confirmed from the above table that better effects could be obtained when any one of requirements 1-1 to 6-1 was satisfied. [Explanation of symbols]

[0123] 10, 10A, 10B, 10C, 10D, 10E, 10F Circular polarizer 12 Polarizer 14, 14A, 14B, 14C, 14D, 14E, 14F First optically anisotropic layer 16, 16A, 16B, 16C, 16D, 16E, 16F Second optically anisotropic layer

Claims

1. A circularly polarizing plate having a polarizer, a first optically anisotropic layer, and a second optically anisotropic layer in this order, the first optically anisotropic layer is a layer in which a liquid crystal compound is fixed and twisted along a helical axis extending in a thickness direction, the second optically anisotropic layer is an A plate, an absorption axis of the polarizer and an in-plane slow axis of the second optically anisotropic layer are parallel to or perpendicular to each other; a value of the product Δnd of the refractive index anisotropy Δn of the first optically anisotropic layer at a wavelength of 550 nm and the thickness d of the first optically anisotropic layer satisfies the relationship of formula (1), the in-plane retardation Re(550) of the second optically anisotropic layer at a wavelength of 550 nm satisfies the relationship of formula (2), Formula (1) 317nm≦Δnd≦377nm Formula (2) 67.5nm≦Re(550)≦127.5nm When the circular polarizing plate is observed from the polarizer side, and the absorption axis of the polarizer is taken as 90°, and a counterclockwise direction is expressed as a positive angle value, the angle of the in-plane slow axis on the surface of the first optically anisotropic layer on the polarizer side is defined as X. When the circular polarizing plate is observed from the polarizer side, and the in-plane slow axis on the surface of the first optically anisotropic layer on the polarizer side is taken as a reference, and a counterclockwise direction is expressed as a positive angle value and a clockwise direction is expressed as a negative angle value, the twist angle of the liquid crystal compound in the first optically anisotropic layer is defined as Y. when the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are parallel to each other, X and Y satisfy any one of requirements 1 to 4, Requirement 1: 0°≦X<20°, and −X+20°≦Y≦−X+60° Requirement 2: 0°≦X≦20°, and -X-60°≦Y≦-X-20° Requirement 3: 160°≦X≦180°, and −X+200°≦Y≦−X+240° Requirement 4: 160°<X≦180°, and −X+120°≦Y≦−X+160° A circularly polarizing plate, wherein X and Y satisfy requirement 5 or 6 when the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are perpendicular to each other. Requirement 5: 70°≦X<110°, and −X+110°≦Y≦−X+150° Requirement 6: 70°<X≦110°, and −X+30°≦Y≦−X+70°

2. a value of the product Δnd of the refractive index anisotropy Δn of the first optically anisotropic layer at a wavelength of 550 nm and the thickness d of the first optically anisotropic layer satisfies the relationship of formula (1-1), the in-plane retardation Re(550) of the second optically anisotropic layer at a wavelength of 550 nm satisfies the relationship of formula (2-1), Formula (1-1) 327nm≦Δnd≦367nm Formula (2-1) 77.5nm≦Re(550)≦117.5nm when the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are parallel to each other, X and Y satisfy any one of requirements 1-1 to 4-1; Requirement 1-1: 0°≦X<20°, and −X+30°≦Y≦−X+50° Requirement 2-1: 0°≦X≦20°, and -X-50°≦Y≦-X-30° Requirement 3-1: 160°≦X≦180°, and -X+210°≦Y≦-X+230° Requirement 4-1: 160°<X≦180°, and -X+130°≦Y≦-X+150° 2. The circularly polarizing plate according to claim 1, wherein, when the absorption axis of the polarizer and the in-plane slow axis of the second optically anisotropic layer are perpendicular to each other, X and Y satisfy requirement 5-1 or 6-1. Requirement 5-1: 70°≦X<110°, and −X+120°≦Y≦−X+140° Requirement 6-1: 70°<X≦110°, and -X+40°≦Y≦-X+60°

3. 3. The circularly polarizing plate according to claim 1, wherein the second optically anisotropic layer is a stretched film or a layer in which a liquid crystal compound is fixed.

4. A display device comprising the circular polarizer according to any one of claims 1 to 3.

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