Circular polarizer

Abstract

To provide a circular polarization plate suitable for an on-vehicle display, which can reduce reflected light upon reflecting display light on a windshield in a vehicle and can reduce change in color of the reflected light.SOLUTION: A circular polarization plate has a first optically anisotropic layer, a polarizer, and a second optically anisotropic layer in this order from a viewing side. The first optically anisotropic layer has optical characteristics represented by Re(450) / Re(550)≤1.00, 1.00≤Re(650) / Re(550), 90 nm≤Re(550)≤180 nm. The first optically anisotropic layer and the second optically anisotropic layer are layers containing a polymer polymerized in a state in which a polymerizable liquid crystal compound is oriented.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a circular polarizing plate, and more particularly to an organic electroluminescent (hereinafter also referred to as organic EL) display device equipped with a circular polarizing plate. [Background technology]

[0002] In recent years, image display devices, such as organic EL displays, have become rapidly widespread. Generally, organic EL displays are equipped with a circular polarizer having a polarizer and a λ / 4 plate in that order from the viewing side. Patent Document 1 proposes a λ / 4 plate formed from a composition containing a liquid crystal compound. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2015-187717 [Overview of the project] [Problems that the invention aims to solve]

[0004] Image display devices equipped with circular polarizers are sometimes used as in-vehicle displays. When such displays are illuminated inside a vehicle at night, the light from the display may reflect off the windshield, and the color change of the reflected light may vary greatly depending on the viewing angle, potentially compromising driving safety.

[0005] The present invention aims to provide a circular polarizing plate suitable for in-vehicle displays that reduces reflected light when display light is reflected off the windshield inside a vehicle, reduces color changes of the reflected light, and has excellent light resistance. [Means for solving the problem]

[0006] The present invention provides the following circular polarizer and organic electroluminescent display device. [1] A circular polarizer having, from the viewing side, a first optical anisotropy layer, a polarizer, and a second optical anisotropy layer in that order, The first optical anisotropy layer is given by the following formulas (I), (II), and (III): Re(450) / Re(550)≦1.00 (I) 1.00 ≤ Re(650) / Re(550) (II) 90nm ≤ Re(550) ≤ 180nm (III) [In the formula, Re(450) represents the in-plane phase difference value at a wavelength of 450 nm in the optically anisotropic layer.] Re(550) represents the in-plane phase difference value at a wavelength of 550 nm in the optically anisotropic layer. Re(650) represents the in-plane phase difference value at a wavelength of 650 nm in the optically anisotropic layer. It has optical properties represented by, A circular polarizing plate in which the first optical anisotropic layer and the second optical anisotropic layer are layers containing polymers obtained by polymerizing polymerizable liquid crystal compounds in an oriented state. [2] The circular polarizer according to [1], wherein the second optical anisotropy layer has optical properties represented by formula (III). [3] The circular polarizer according to [1] or [2], wherein the second optical anisotropy layer further comprises formula (I) and formula (II). [4] The following formula (IV): 200nm ≤ Re(550) ≤ 320nm (IV) A circular polarizer according to any one of [1] to [3], further comprising a third optical anisotropic layer having optical properties represented by [wherein Re(550) represents the in-plane phase difference value of the optical anisotropic layer at a wavelength of 550 nm]. [5] A circular polarizer according to any one of [1] to [4], wherein the angle between the slow axis of the first optical anisotropy layer and the slow axis of the second optical anisotropy layer is 90° ± 10°. [6] The circular polarizer according to any one of [1] to [5], wherein the polarizer is a polarizer in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol-based resin film. [7] The circular polarizing plate according to any one of [1] to [5], wherein the polarizer is a polarizer in which a dichroic dye is oriented in a cured film obtained by polymerization of a polymerizable liquid crystal compound. [8] An organic electroluminescence display device including the circular polarizing plate according to any one of [1] to [7]. [9] An in-vehicle display including the organic electroluminescence display device according to [8]. [Advantages of the Invention]

[0007] According to the present invention, it is possible to provide a circular polarizing plate suitable for an in-vehicle display, which reduces the reflected light when the in-vehicle display light is reflected by the windshield, reduces the color change of the reflected light, and has excellent light resistance. [Brief Description of the Drawings]

[0008] [Figure 1] It is an example of a schematic cross-sectional view showing the layer structure of the circular polarizing plate. [Figure 2] It is an example of a schematic cross-sectional view showing the layer structure of the circular polarizing plate. [Figure 3] It is an example of a schematic cross-sectional view showing the layer structure of the circular polarizing plate. [Figure 4] It is an example of a schematic cross-sectional view showing the layer structure of the circular polarizing plate. [Figure 5] It is an example of a schematic cross-sectional view showing the layer structure of the circular polarizing plate. [Figure 6] It is an example of a schematic cross-sectional view showing an example of a method for manufacturing the circular polarizing plate. [Figure 7] It is an example of a schematic cross-sectional view showing the layer structure of the organic EL display device. [Figure 8] It is a schematic view showing a method for evaluating the reflected light of display light. [Modes for Carrying Out the Invention]

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In all the following drawings, the scales are appropriately adjusted for easy understanding of each component, and the scales of each component shown in the drawings do not necessarily match the scales of the actual components.

[0010] <Circular polarizing plate> The circular polarizing plate of the present invention has a first optical anisotropic layer, a polarizer, and a second optical anisotropic layer in this order. The first optical anisotropic layer, the second optical anisotropic layer, and the polarizer can be laminated via, for example, an adhesive layer described later.

[0011] Hereinafter, with reference to FIG. 1, an example of the layer structure of the circular polarizing plate of the present invention will be described. The circular polarizing plate 100 shown in FIG. 1 has a layer structure in which a first optical anisotropic layer 11, a polarizer 10, and a second optical anisotropic layer 12 are laminated in order from the viewing side. The viewing side means the side opposite to the image display element side of the circular polarizing plate 100 when the circular polarizing plate 100 is applied to an image display device.

[0012] The circular polarizing plate 100 can have layers other than the layers shown in FIG. 1. Examples of the layers that the circular polarizing plate 100 may further have include a front panel, a protective film, a light-shielding pattern, an adhesive layer, and the like.

[0013] The shape of the main surface of the circular polarizing plate 100 can be substantially rectangular. The main surface means the surface having the largest area corresponding to the display surface. Substantially rectangular means a shape in which at least one of the four corners (corners) is cut off so that the corner is an obtuse angle, or a shape provided with a roundness, or a recess (notch) in which a part of the end face perpendicular to the main surface is recessed in the in-plane direction, or a part in the main surface has a hole part hollowed out in a shape such as a circle, an ellipse, a polygon, and a combination thereof.

[0014] The size of the circular polarizer 100 is not particularly limited. If the circular polarizer 100 is substantially rectangular, the length of the longer side is preferably 6 cm or more and 35 cm or less, more preferably 10 cm or more and 30 cm or less, and the length of the shorter side is preferably 5 cm or more and 30 cm or less, more preferably 6 cm or more and 25 cm or less.

[0015] (Optical anisotropy layer) The first optical anisotropy layer 11 is positioned on the viewing side of the circular polarizer 100 compared to the second optical anisotropy layer 12. The first optical anisotropy layer 11 has optical properties represented by formulas (I), (II), and (III). Re(450) / Re(550)≦1.00 (I) 1.00 ≤ Re(650) / Re(550) (II) 90nm ≤ Re(550) ≤ 180nm (III) [In the formula, Re(450) represents the in-plane phase difference value at a wavelength of 450 nm in the optically anisotropic layer.] Re(550) represents the in-plane phase difference value at a wavelength of 550 nm in the optically anisotropic layer. Re(650) represents the in-plane phase difference value at a wavelength of 650 nm in the optically anisotropic layer. The in-plane phase difference value is defined by the following formula. Re(λ)=(nx(λ)-ny(λ))×d [In the formula, Re(λ) represents the in-plane phase difference value of the optical anisotropy layer at a wavelength of λnm, d represents the thickness of the optical anisotropy layer, nx represents the principal refractive index at a wavelength of λnm in the direction parallel to the plane of the optical anisotropy layer in the refractive index ellipsoid formed by the optical anisotropy layer, and ny represents the refractive index at a wavelength of λnm in the direction parallel to the plane of the optical anisotropy layer and perpendicular to the direction of nx in the refractive index ellipsoid formed by the optical anisotropy layer.]

[0016] The first optical anisotropy layer 11 can have inverse wavelength dispersion by having optical properties represented by formulas (I) and (II). Preferably, the first optical anisotropy layer 11 has optical properties represented by formula (I-1), and more preferably by formula (I-2). Re(450) / Re(550)≦0.93 (I-1) 0.81 ≤ Re(450) / Re(550) (I-2)

[0017] The first optical anisotropic layer 11 preferably has optical properties represented by formula (II-1), and more preferably has optical properties represented by formula (II-2). 1.00 <Re(650) / Re(550) (II-1) Re(650) / Re(550)≦1.10 (II-2)

[0018] The first optical anisotropic layer 11 preferably has optical properties represented by formula (III-1), and more preferably has optical properties represented by formula (III-2). 100nm≦Re(550)≦160nm (III-1) 110nm≦Re(550)≦150nm (III-2) When the first optical anisotropy layer 11 has the above optical properties, color changes and coloring tend to be reduced when the display device is viewed from an oblique angle.

[0019] The second optical anisotropy layer 12 may have optical properties represented by formula (III). Preferably, the second optical anisotropy layer 12 has optical properties represented by formula (III-1), and more preferably, optical properties represented by formula (III-2). The second optical anisotropy layer 12 can have inverse wavelength dispersion by further possessing optical properties represented by formulas (I) and (II). The second optical anisotropy layer 12 preferably has optical properties represented by formula (I-1), and more preferably has optical properties represented by formula (I-2). The second optical anisotropy layer 12 preferably has optical properties represented by formula (II-1), and more preferably has optical properties represented by formula (II-2). When the second optical anisotropy layer 12 has the above optical properties, color changes and coloring tend to be reduced when the display device is viewed from an oblique angle.

[0020] A circular polarizer is given by equation (IV): 200nm ≤ Re(550) ≤ 320nm (IV) A third optical anisotropic layer having optical properties represented by the formula [wherein Re(550) represents the in-plane phase difference value of the optical anisotropic layer at a wavelength of 550 nm] may be further provided.

[0021] The third optical anisotropic layer is preferably an optical anisotropic layer having optical properties represented by formula (IV-1), and more preferably an optical anisotropic layer having optical properties represented by formula (IV-2). 250nm≦Re(550)≦300nm (IV-1) 265nm≦Re(550)≦285nm (IV-2)

[0022] The third optical anisotropy layer is given by equation (V): nx≒ny <nz (V) It may also have optical properties represented by the following: nx represents the principal refractive index in the refractive index ellipsoid formed by the optical anisotropy layer, in the direction parallel to the plane of the optical anisotropy layer. ny represents the refractive index in the refractive index ellipsoid formed by the optical anisotropy layer, in the direction parallel to the plane of the optical anisotropy layer and perpendicular to the direction of nx. nz represents the refractive index in the refractive index ellipsoid formed by the optical anisotropy layer, in the direction perpendicular to the plane of the optical anisotropy layer.

[0023] If the circular polarizer 100 has a third optical anisotropy layer, the third optical anisotropy can be located between the polarizer 10 and the second optical anisotropy layer 12, or on the side of the second optical anisotropy layer 12 opposite to the polarizer 10.

[0024] The first optical anisotropy layer 11, the second optical anisotropy layer 12, and the third optical anisotropy layer may include the alignment films described later.

[0025] The first optical anisotropy layer 11 is preferably a phase difference layer that has inverse wavelength dispersion and provides a phase difference of λ / 4. The second optically anisotropic layer 12 can be a retardation layer such as a layer that provides a retardation of, for example, λ / 4 (positive A layer), a layer that provides a retardation of λ / 2, and a positive C layer. The second optically anisotropic layer 12 is preferably a layer that provides a retardation of λ / 4, and more preferably a retardation layer that has reverse wavelength dispersion and provides a retardation of λ / 4. The third optically anisotropic layer can be a retardation layer such as a layer that provides a retardation of λ / 2 and a positive C layer. The third optically anisotropic layer is preferably a layer that provides a retardation of λ / 2.

[0026] The layer that provides a retardation of λ / 4 means a layer in which the in-plane retardation value at a wavelength of 550 nm is preferably 90 nm or more and 180 nm or less, more preferably 100 nm or more and 160 nm or less, and even more preferably the in-plane retardation value is 110 nm or more and 150 nm or less. The layer that provides a retardation of λ / 2 means a layer in which the in-plane retardation value at a wavelength of 550 nm is preferably 200 nm or more and 320 nm or less, more preferably the in-plane retardation value is 250 nm or more and 300 nm or less, and even more preferably the in-plane retardation value is 265 nm or more and 285 nm or less. The positive C layer can be a layer that exhibits the refractive index relationship of nx≒ny<nz. The retardation value in the thickness direction of the positive C layer can be -150 nm or more and -30 nm or less at a wavelength of 550 nm, and can be -120 nm or more and -50 nm or less.

[0027] The retardation value in the thickness direction is defined by the following formula. Rth(λ)=[{nx(λ)+ny(λ)} / 2 - nz(λ)]×d [In the formula, Rth(λ) represents the phase difference value in the thickness direction at a wavelength of λnm of the optical anisotropy layer, d represents the thickness of the optical anisotropy layer, nx(λ) represents the principal refractive index at a wavelength of λnm in the direction parallel to the plane of the optical anisotropy layer in the refractive index ellipsoid formed by the optical anisotropy layer, ny(λ) represents the refractive index at a wavelength of λnm in the direction parallel to the plane of the optical anisotropy layer and perpendicular to the direction of nx(λ) in the refractive index ellipsoid formed by the optical anisotropy layer, and nz(λ) represents the refractive index at a wavelength of λnm in the direction perpendicular to the film plane in the refractive index ellipsoid formed by the optical anisotropy layer.]

[0028] The slow axis of the first optical anisotropy layer 11 and the second optical anisotropy layer 12 may have an angle of, for example, 45°±10° with respect to the absorption axis of the polarizer 10, from the viewpoint of function as a circular polarizer, preferably 45°±5°, and more preferably 45°±2°.

[0029] The angle between the slow axis of the first optical anisotropy layer 11 and the slow axis of the second optical anisotropy layer 12 is preferably 90°±15°, more preferably 90°±10°, even more preferably 90°±5°, and particularly preferably 90°, from the viewpoint of suppressing curling.

[0030] When the second optical anisotropy layer 12 has optical properties represented by formula (III), preferably the angle between the slow axis of the second optical anisotropy layer 12 and the absorption axis of the polarizer 10 is 45°, and the angle between the slow axis of the first optical anisotropy layer 11 and the slow axis of the second optical anisotropy layer 12 is 90°.

[0031] The first optical anisotropic layer 11 and the second optical anisotropic layer 12 are layers containing polymers (hereinafter also referred to as cured layers) in which polymerizable liquid crystal compounds are polymerized in an oriented state. If the circular polarizer contains a third optical anisotropic layer, the third optical anisotropic layer may be a cured layer. The cured layer is formed, for example, on an alignment film provided on a substrate. The substrate may be a long substrate that has the function of supporting the alignment film. This substrate functions as a release support and can support the cured layer for transfer. Furthermore, it is preferable that its surface has sufficient adhesive strength to be peelable. Examples of substrates include resin films, which will be exemplified as materials for protective films later. The substrate and the alignment film may be contained within the circular polarizer. The alignment film may be removed together with the substrate when the substrate is removed. The first optical anisotropy layer 11 includes a cured layer and satisfies the above formulas (I), (II), and (III), which makes it possible to reduce the reflected light when the in-car display light is reflected off the windshield, reduce the color change of the reflected light, and tend to improve the light resistance of the circular polarizer.

[0032] The thickness of the base material is not particularly limited, but can be in the range of 20 μm to 200 μm. When the thickness of the base material is 20 μm or more, it tends to be easier to impart strength. On the other hand, when the thickness is 200 μm or less, it tends to be easier to suppress the increase in processing waste and wear of the cutting blade when cutting the base material into individual sheets.

[0033] The substrate may be subjected to various anti-blocking treatments. Examples of anti-blocking treatments include easy-adhesion treatments, treatments involving the incorporation of fillers, and embossing (knurling). By applying such anti-blocking treatments to the substrate, it is possible to effectively prevent the substrates from sticking together when winding them up, so-called blocking, and to manufacture optical films with high productivity.

[0034] The cured layer is formed on the substrate via an alignment film. That is, the substrate and the alignment film are laminated in that order, and the layer in which the polymerizable liquid crystal compound has cured is laminated on top of the alignment film.

[0035] The alignment film is not limited to a vertical alignment film; it may also be an alignment film that horizontally aligns the molecular axis of the polymerizable liquid crystal compound, or an alignment film that tilts the molecular axis of the polymerizable liquid crystal compound. Preferably, the alignment film has solvent resistance so as not to dissolve when coated with a composition containing the polymerizable liquid crystal compound described later, and also has heat resistance for solvent removal and heat treatment for alignment of the polymerizable liquid crystal compound. Examples of alignment films include an alignment film containing an aligning polymer, a photo-alignment film, and a groove-alignment film that forms an uneven pattern or multiple grooves on its surface for alignment. The thickness of the alignment film is usually in the range of 10 nm to 10,000 nm, preferably in the range of 10 nm to 1,000 nm, more preferably 500 nm or less, and even more preferably in the range of 10 nm to 20 nm.

[0036] The resin used for the orientation film is not particularly limited as long as it is a resin used as a known material for orientation films, and conventionally known monofunctional or polyfunctional (meth)acrylate monomers cured under polymerization initiators can be used. Specifically, examples of (meth)acrylate monomers include 2-ethylhexyl acrylate, cyclohexyl acrylate, diethylene glycol mono-2-ethylhexyl ether acrylate, diethylene glycol monophenyl ether acrylate, tetraethylene glycol monophenyl ether acrylate, trimethylolpropane triacrylate, lauryl acrylate, lauryl methacrylate, isobornyl acrylate, isobornyl methacrylate, 2-phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, 2-hydroxypropyl acrylate, benzyl acrylate, tetrahydrofurfuryl methacrylate, 2-hydroxyethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, methacrylic acid, urethane acrylate, and the like. These resins can be used individually or as a mixture of two or more types.

[0037] While there are no particular limitations on the types of polymerizable liquid crystal compounds, they can be classified into rod-shaped types (rod-shaped liquid crystal compounds) and disc-shaped types (discotic liquid crystal compounds). Furthermore, each of these can be further divided into low-molecular-weight and high-molecular-weight types. Note that high-molecular-weight compounds generally refer to those with a degree of polymerization of 100 or more (Polymer Physics and Phase Transition Dynamics, by Masao Doi, p. 2, Iwanami Shoten, 1992). In this embodiment, any polymerizable liquid crystal compound can be used. Furthermore, two or more rod-shaped liquid crystal compounds, two or more disc-shaped liquid crystal compounds, or mixtures of rod-shaped and disc-shaped liquid crystal compounds may be used.

[0038] As the rod-shaped liquid crystal compound, for example, those described in claim 1 of Japanese Patent Publication No. 11-513019, or paragraphs

[0026] to

[0098] of Japanese Patent Application Publication No. 2005-289980 can be suitably used. As the disc-shaped liquid crystal compound, for example, those described in paragraphs

[0020] to

[0067] of Japanese Patent Application Publication No. 2007-108732, or paragraphs

[0013] to

[0108] of Japanese Patent Application Publication No. 2010-244038 can be suitably used.

[0039] Polymerizable liquid crystal compounds have polymerizable groups capable of polymerization reactions. Preferred polymerizable groups include functional groups that can undergo addition polymerization reactions, such as polymerizable ethylenically unsaturated groups and cyclic polymerizable groups. More specifically, examples of polymerizable groups include (meth)acryloyl groups, vinyl groups, styryl groups, and allyl groups. Among these, (meth)acryloyl groups are preferred. Note that the (meth)acryloyl group is a concept that encompasses both methacryloyl groups and acryloyl groups.

[0040] More than one polymerizable liquid crystal compound may be used in combination, in which case at least one of them must have two or more polymerizable groups in its molecule. The polymerizable liquid crystal compound does not need to exhibit liquid crystalline properties after it has polymerized. The polymerizable liquid crystal compounds used to form the first optical anisotropy layer, the second optical anisotropy layer, and the third optical anisotropy layer may be the same polymerizable liquid crystal compound or different polymerizable liquid crystal compounds.

[0041] The cured layer can be formed by coating a composition containing a polymerizable liquid crystal compound (hereinafter also referred to as a polymerizable liquid crystal composition) onto, for example, an alignment film, and curing it by irradiation with active energy rays, as described later. The polymerizable liquid crystal composition may contain components other than the polymerizable liquid crystal compound described above. For example, it is preferable that the polymerizable liquid crystal composition contains a polymerization initiator. Depending on the type of polymerization reaction, the polymerization initiator used may be selected, for example, a thermal polymerization initiator or a photopolymerization initiator. For example, examples of photopolymerization initiators include α-carbonyl compounds, acyloin ethers, α-hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, and combinations of triarylimidazole dimers and p-aminophenyl ketones. The amount of polymerization initiator used is preferably 0.01% to 20% by mass, and more preferably 0.5% to 5% by mass, relative to the total solid content in the polymerizable liquid crystal composition.

[0042] Furthermore, polymerizable liquid crystal compositions may contain polymerizable monomers from the viewpoint of uniformity of the coating film and strength of the film. Examples of polymerizable monomers include radical polymerizable or cationic polymerizable compounds. Among these, polyfunctional radical polymerizable monomers are preferred.

[0043] Furthermore, it is preferable that the polymerizable monomer can copolymerize with the polymerizable liquid crystal compound described above. The amount of polymerizable monomer used is preferably 1% to 50% by mass, and more preferably 2% to 30% by mass, relative to the total mass of the polymerizable liquid crystal compound.

[0044] Furthermore, polymerizable liquid crystal compositions may contain surfactants from the viewpoint of uniformity and strength of the coating film. Examples of surfactants include conventionally known compounds. Among these, fluorine-based compounds are particularly preferred.

[0045] Furthermore, polymerizable liquid crystal compositions may contain a solvent, and organic solvents are preferably used. Examples of organic solvents include amides (e.g., N,N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene, hexane), alkyl halides (e.g., chloroform, dichloromethane), esters (e.g., methyl acetate, ethyl acetate, butyl acetate), ketones (e.g., acetone, methyl ethyl ketone), and ethers (e.g., tetrahydrofuran, 1,2-dimethoxyethane). Among these, alkyl halides and ketones are preferred. In addition, two or more organic solvents may be used in combination.

[0046] Furthermore, the polymerizable liquid crystal composition may contain various alignment agents, such as vertical alignment agents, including polarizer interface-side vertical alignment agents and air interface-side vertical alignment agents, as well as horizontal alignment agents, including polarizer interface-side horizontal alignment agents and air interface-side horizontal alignment agents. In addition, the polymerizable liquid crystal composition may contain other components besides those mentioned above, such as adhesion improvers, plasticizers, and polymers.

[0047] The above-mentioned active energy rays include ultraviolet light, visible light, electron beams, and X-rays, and are preferably ultraviolet light. Examples of light sources for the active energy rays include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources emitting in the wavelength range of 380 to 44 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, and the like.

[0048] The intensity of ultraviolet radiation is typically 100 mW / cm². 2 More than 3,000mW / cm 2 The following applies: The ultraviolet irradiation intensity is preferably in the wavelength range effective for activating the cationic polymerization initiator or radical polymerization initiator. The irradiation time with ultraviolet light is usually 0.1 seconds to 10 minutes, preferably 0.1 seconds to 5 minutes, more preferably 0.1 seconds to 3 minutes, and even more preferably 0.1 seconds to 1 minute.

[0049] Ultraviolet light can be irradiated once or in multiple passes. Multiple irradiations of ultraviolet light are preferable. As the polymerization rate of the liquid crystal compound increases, the puncture modulus tends to increase. Depending on the polymerization initiator used, the integrated light intensity at a wavelength of 365 nm is approximately 700 mJ / cm². 2 Preferably, it should be 1,100 mJ / cm² or higher. 2 It is more preferable to set it to 1,300 mJ / cm² or higher. 2 It is even more preferable to set it to the above. Setting the above integrated light intensity is advantageous for increasing the polymerization rate of the polymerizable liquid crystal compound constituting the optical anisotropic layer. The integrated light intensity at a wavelength of 365 nm is 2,000 mJ / cm². 2 Preferably, the following is used: 1,800 mJ / cm² 2 The following is more preferable. Using the above integrated light quantity may cause discoloration of the optical anisotropy layer.

[0050] Furthermore, to prevent the orientation of the liquid crystal compound from being disrupted by the heat immediately after UV irradiation, it is preferable to include a cooling step after UV irradiation. By including a cooling step after UV irradiation, the disruption of the orientation of the liquid crystal compound due to the heat generated immediately after irradiation can be suppressed. As a result, the degree of orientation of the liquid crystal compound increases, and a film with higher rigidity can be obtained. The cooling temperature can be, for example, 20°C or lower, or 10°C or lower. The cooling time can be, for example, 10 seconds or more, or 20 seconds or more.

[0051] The thickness of the optical anisotropy layer is preferably 0.5 μm or more. Furthermore, the thickness of the optical anisotropy layer is preferably 10 μm or less, and more preferably 5 μm or less. The above-mentioned upper and lower limits can be combined arbitrarily. If the thickness of the optical anisotropy layer is greater than or equal to the lower limit, sufficient durability can be obtained. If the thickness of the optical anisotropy layer is less than or equal to the upper limit, it can contribute to the thinning of the circular polarizer. The thickness of the optical anisotropy layer can be adjusted to obtain a desired in-plane phase difference value and a phase difference value in the thickness direction for a layer that gives a phase difference of λ / 4, a layer that gives a phase difference of λ / 2, or a positive C layer.

[0052] When the circular polarizer includes a third optical anisotropy layer, the second and third optical anisotropy layers can be manufactured by creating cured layers on an alignment film and laminating them together via an adhesive layer. After lamination, the substrate and the alignment film can be peeled off. The thicknesses of the first optical anisotropy layer 11, the second optical anisotropy layer 12, and the third optical anisotropy layer are preferably 0.1 μm to 15 μm, more preferably 0.3 μm to 10 μm, and even more preferably 0.5 μm to 8 μm. The thicknesses of the first optical anisotropy layer 11, the second optical anisotropy layer 12, and the third optical anisotropy layer may be the same or different.

[0053] (Polarizer) A polarizer can be an absorbing type polarizer that absorbs linearly polarized light having a vibration plane parallel to its absorption axis and transmits linearly polarized light having a vibration plane perpendicular to the absorption axis (parallel to the transmission axis). A suitable polarizer is one in which a dichroic dye is adsorbed and oriented onto a uniaxially stretched polyvinyl alcohol-based resin film. A polarizer can be manufactured, for example, by a method including the steps of: uniaxially stretching a polyvinyl alcohol-based resin film; dyeing the polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dye; treating the polyvinyl alcohol-based resin film with the adsorbed dichroic dye with a crosslinking solution such as an aqueous boric acid solution; and washing with water after treatment with the crosslinking solution.

[0054] As the polyvinyl alcohol-based resin, a saponified polyvinyl acetate-based resin can be used. Examples of polyvinyl acetate-based resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylamides having an ammonium group.

[0055] In this specification, "(meth)acrylic" means at least one selected from acrylic and methacrylic. The same applies to "(meth)acryloyl," "(meth)acrylate," etc.

[0056] The degree of saponification of the polyvinyl alcohol resin is usually between 85 mol% and 100 mol%, with 98 mol% or higher being preferred. The polyvinyl alcohol resin may be modified; for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can be used. The average degree of polymerization of the polyvinyl alcohol resin is usually between 1000 and 10000, with 1500 and 5000 being preferred. The average degree of polymerization of the polyvinyl alcohol resin can be determined in accordance with JIS K 6726.

[0057] A film made from such a polyvinyl alcohol-based resin is used as the base film for polarizers. The method for producing the polyvinyl alcohol-based resin film is not particularly limited, and known methods can be used. The thickness of the polyvinyl alcohol-based base film is not particularly limited, but in order to make the thickness of the polarizer 15 μm or less, it is preferable to use one that is between 5 μm and 35 μm. More preferably, it is 20 μm or less.

[0058] Uniaxial stretching of polyvinyl alcohol-based resin films can be performed before, simultaneously with, or after dyeing with a dichroic dye. If uniaxial stretching is performed after dyeing, it may be performed before or during the crosslinking process. Furthermore, uniaxial stretching may be performed at multiple stages.

[0059] Uniaxial stretching may be performed using rolls with different peripheral speeds, or using heated rolls. Uniaxial stretching may also be performed using dry stretching in the atmosphere, or wet stretching in which the polyvinyl alcohol-based resin film is swollen with a solvent or water before stretching. The stretching ratio is usually between 3 and 8 times.

[0060] One method for dyeing a polyvinyl alcohol-based resin film with a dichroic dye is to immerse the film in an aqueous solution containing the dichroic dye. Iodine or dichroic organic dyes are used as the dichroic dye. It is preferable to immerse the polyvinyl alcohol-based resin film in water before the dyeing treatment.

[0061] For crosslinking treatment after dyeing with a dichroic dye, a method is usually employed in which the dyed polyvinyl alcohol-based resin film is immersed in a boric acid-containing aqueous solution. When iodine is used as the dichroic dye, it is preferable that this boric acid-containing aqueous solution contains potassium iodide.

[0062] The thickness of the polarizer is usually 30 μm or less, preferably 15 μm or less, more preferably 13 μm or less, even more preferably 10 μm or less, and particularly preferably 8 μm or less. The thickness of the polarizer is usually 2 μm or more, preferably 3 μm or more.

[0063] As a polarizer, for example, as described in Japanese Patent Publication No. 2016-170368, a polarizer may be used in which a dichroic dye is oriented in a cured film polymerized from a liquid crystal compound. As the dichroic dye, one that has absorption in the wavelength range of 380 nm to 800 nm can be used, and it is preferable to use an organic dye. Examples of dichroic dyes include azo compounds. The liquid crystal compound is a liquid crystal compound that can be polymerized while maintaining orientation and can have polymerizable groups in its molecule. Alternatively, as described in WO2011 / 024891, a polarizer may be formed from a liquid crystal dichroic dye.

[0064] (Protective film) A circular polarizer may have one or more protective films. The protective films may have the function of protecting the optical anisotropy, polarizer, etc. The protective films may be placed on one or both sides of at least one of the optical anisotropy layer and the polarizer, preferably on at least one of the side of the optical anisotropy layer opposite the polarizer and the viewing side of the polarizer, and more preferably on at least one of the side of the first optical anisotropy layer opposite the polarizer and the viewing side of the polarizer. The optical anisotropy layer or polarizer and the protective film can be bonded together, for example, via an adhesive layer as described later. Hereinafter, a laminate consisting of a polarizer and a protective film will also be called a linear polarizer.

[0065] When the circular polarizer is substantially rectangular and the protective film is a stretched film, it is preferable that the stretching direction of the protective film and the short-side direction of the circular polarizer are substantially parallel. When the stretching direction and the short-side direction are in this relationship, the hue change of the circular polarizer tends to be smaller in high-temperature environments, regardless of the direction of the slow-phase axis of the phase difference film. When the stretching direction of the protective film is parallel to the short side, the contraction force of the protective film in the stretching direction due to the relaxation of the polarizer and protective film in high-temperature environments is smaller compared to when it is parallel to the long side, and it is thought that the hue change is smaller.

[0066] The stretching direction of the protective film and the short-side direction of the circular polarizer are substantially parallel, which includes not only cases where they are strictly parallel, but also cases where the angle between them is 0 ± 10°. The angle between the stretching direction of the protective film and the short-side direction of the circular polarizer is preferably 0 ± 5°.

[0067] The protective film may be made of a light-transmitting (preferably optically transparent) thermoplastic resin, such as polyolefin resins like chain polyolefin resins (polypropylene resins, etc.) and cyclic polyolefin resins (norbornene resins, etc.); cellulose resins like triacetylcellulose and diacetylcellulose; polyester resins like polyethylene terephthalate and polybutylene terephthalate; polycarbonate resins; (meth)acrylic resins like methyl methacrylate resins; polystyrene resins; polyvinyl chloride resins; acrylonitrile-butadiene-styrene resins; acrylonitrile-styrene resins; polyvinyl acetate resins; polyvinylidene chloride resins; polyamide resins; polyacetal resins; modified polyphenylene ether resins; polysulfone resins; polyethersulfone resins; polyarylate resins; polyamide-imide resins; polyimide resins, etc.

[0068] Examples of chain-like polyolefin resins include homopolymers of chain-like olefins such as polyethylene resin (a homopolymer of ethylene, or a copolymer mainly composed of ethylene) and polypropylene resin (a homopolymer of propylene, or a copolymer mainly composed of propylene), as well as copolymers composed of two or more chain-like olefins.

[0069] Cyclic polyolefin resins are a general term for resins polymerized using cyclic olefins as polymerization units, and examples include resins described in Japanese Patent Publication No. 1-240517, Japanese Patent Publication No. 3-14882, and Japanese Patent Publication No. 3-122137. Specific examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins with chain-like olefins such as ethylene and propylene (typically random copolymers), graft polymers modified with unsaturated carboxylic acids or their derivatives, and their hydrides. Among these, norbornene resins using norbornene monomers such as norbornene or polycyclic norbornene monomers as the cyclic olefin are preferred.

[0070] Polyester resins, excluding the cellulose ester resins described below, are resins containing ester bonds and are generally composed of polycondensates of polycarboxylic acids or their derivatives and polyhydric alcohols. Divalent dicarboxylic acids or their derivatives can be used as polycarboxylic acids or their derivatives, such as terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalenedicarboxylate. Divalent diols can be used as polyhydric alcohols, such as ethylene glycol, propanediol, butanediol, neopentyl glycol, and cyclohexanedimethanol. A representative example of a polyester resin is polyethylene terephthalate, which is a polycondensate of terephthalic acid and ethylene glycol.

[0071] (Meth)acrylic resins are resins whose main constituent monomers are compounds having a (meth)acryloyl group. Specific examples of (meth)acrylic resins include, for example, poly(meth)acrylic acid esters such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymers; methyl methacrylate-(meth)acrylic acid ester copolymers; methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymers; (meth)acrylic acid-styrene copolymers (MS resin, etc.); and copolymers of methyl methacrylate and compounds having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth)acrylic acid copolymer, etc.). Preferably, poly(meth)acrylic acid C such as poly(meth)acrylate 1-6 A polymer mainly composed of alkyl esters is used, and more preferably, a methyl methacrylate resin mainly composed of methyl methacrylate (50% to 100% by mass, preferably 70% to 100% by mass) is used.

[0072] Cellulose ester resins are esters of cellulose and fatty acids. Specific examples of cellulose ester resins include cellulose triacetate, cellulose diacetate, cellulose trippropionate, and cellulose dipropionate. Also included are copolymers of these, and those in which some of the hydroxyl groups are modified with other substituents. Among these, cellulose triacetate (triacetylcellulose) is particularly preferred.

[0073] Polycarbonate resins are engineering plastics composed of polymers in which monomer units are bonded together via carbonate groups.

[0074] The thickness of the protective film is usually between 1 μm and 100 μm, but from the viewpoint of strength and handling, it is preferably between 5 μm and 60 μm, more preferably between 10 μm and 55 μm, and even more preferably between 15 μm and 40 μm.

[0075] If a circular polarizer has two or more protective films, the protective films may be made of the same type of thermoplastic resin or of different types of thermoplastic resin. They may also have the same or different thicknesses. Furthermore, they may have the same or different phase difference characteristics.

[0076] As described above, at least one of the protective films may have a surface treatment layer (coating layer) on its outer surface (the side opposite to the polarizer), such as a hard coat layer, anti-glare layer, light diffusion layer, anti-reflective layer, low refractive index layer, anti-static layer, or anti-fouling layer. The thickness of the protective film includes the thickness of the surface treatment layer.

[0077] The protective film can be bonded to other layers, such as an optical anisotropy layer or a polarizer, via an adhesive layer described later.

[0078] (Adhesive layer) The adhesive layer is placed between the first optical anisotropy layer 11 and the polarizer 10, and between the polarizer 10 and the second optical anisotropy layer 12 or the third optical anisotropy layer. The adhesive layer may be an adhesive layer or a tack layer. The adhesive layer may be a single layer or a multilayer layer.

[0079] As the adhesive forming the adhesive layer, a water-based adhesive, an active energy ray-curable adhesive, or a thermosetting adhesive can be used, and a water-based adhesive or an active energy ray-curable adhesive is preferred. The adhesive layer described later can be used.

[0080] Examples of water-based adhesives include adhesives made from aqueous solutions of polyvinyl alcohol-based resins and water-based two-component urethane emulsion adhesives. Among these, water-based adhesives made from aqueous solutions of polyvinyl alcohol-based resins are preferred. As polyvinyl alcohol-based resins, vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as polyvinyl alcohol copolymers obtained by saponifying a copolymer of vinyl acetate and other monomers copolymerizable thereto, or modified polyvinyl alcohol polymers obtained by partially modifying the hydroxyl groups thereof. Water-based adhesives may contain crosslinking agents such as aldehyde compounds (glyoxal, etc.), epoxy compounds, melamine compounds, methylol compounds, isocyanate compounds, amine compounds, and polyvalent metal salts.

[0081] When using a water-based adhesive, it is preferable to perform a drying step to remove the water contained in the adhesive after bonding the layers together. After the drying step, a curing step may be provided, for example, by curing at a temperature of 20°C to 45°C.

[0082] The above-mentioned active energy ray curable adhesive is an adhesive containing a curable compound that hardens upon irradiation with active energy rays such as ultraviolet light, visible light, electron beams, and X-rays, and is preferably an ultraviolet-curable adhesive.

[0083] The curable compound described above can be a cationically polymerizable curable compound or a radically polymerizable curable compound. Examples of cationically polymerizable curable compounds include epoxy compounds (compounds having one or more epoxy groups in the molecule), oxetane compounds (compounds having one or more oxetane rings in the molecule), or combinations thereof. Examples of radically polymerizable curable compounds include (meth)acrylic compounds (compounds having one or more (meth)acryloyloxy groups in the molecule), other vinyl compounds having a radically polymerizable double bond, or combinations thereof. Cationically polymerizable curable compounds and radically polymerizable curable compounds may be used in combination. Active energy ray curable adhesives usually further include at least one of a cationic polymerization initiator and a radical polymerization initiator for initiating the curing reaction of the curable compound described above.

[0084] The adhesive layer can be composed of an adhesive composition mainly composed of resins such as (meth)acrylic, rubber, urethane, ester, silicone, or polyvinyl ether. Among these, an adhesive composition using a (meth)acrylic resin as the base polymer, which has excellent transparency, weather resistance, and heat resistance, is preferred. The adhesive composition may be of the active energy ray curing type or thermosetting type. The thickness of the adhesive layer is usually 3 μm to 30 μm, preferably 3 μm to 25 μm.

[0085] As the (meth)acrylic resin (base polymer) used in the adhesive composition, polymers or copolymers using one or more (meth)acrylic acid esters as monomers, such as butyl (meth)acrylate, ethyl (meth)acrylate, isooctyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, are preferably used. It is preferable to copolymerize polar monomers into the base polymer. Examples of polar monomers include monomers having carboxyl groups, hydroxyl groups, amide groups, amino groups, epoxy groups, etc., such as (meth)acrylic acid, 2-hydroxypropyl (meth)acrylate, hydroxyethyl (meth)acrylate, (meth)acrylamide, N,N-dimethylaminoethyl (meth)acrylate, and glycidyl (meth)acrylate.

[0086] The adhesive composition may contain only the above-mentioned base polymer, but usually further contains a crosslinking agent. Examples of crosslinking agents include divalent or higher metal ions that form metal carboxylate salts with carboxyl groups; polyamine compounds that form amide bonds with carboxyl groups; polyepoxy compounds or polyols that form ester bonds with carboxyl groups; and polyisocyanate compounds that form amide bonds with carboxyl groups. Among these, polyisocyanate compounds are preferred.

[0087] To enhance adhesion, surface activation treatment may be applied to at least one of the bonding surfaces of the adhesive layer and the layer to be bonded to the adhesive layer. Examples of surface activation treatments include dry treatments such as corona treatment, plasma treatment, electrical discharge treatment (glow discharge treatment, etc.), flame treatment, ozone treatment, UV ozone treatment, and ionizing ray treatment (ultraviolet treatment, electron beam treatment, etc.); and wet treatments such as ultrasonic treatment, saponification treatment, and anchor coating treatment using solvents such as water or acetone. These surface activation treatments may be performed individually or in combination of two or more.

[0088] If two or more adhesive layers are provided, the adhesives used in the adhesive layers may be of the same type or different types. If two or more adhesive layers are provided, the adhesives used in the adhesive layers may be of the same type or different types.

[0089] (Front plate) The front panel is positioned so that it faces the viewer side when the circular polarizer 100 is bonded to the image display element. Preferably, the front panel is positioned so that it is the outermost surface on the viewer side of the circular polarizer 100. When a circular polarizer with the front panel on the outermost surface on the viewer side is used in an image display device, the circular polarizer is positioned so that the front panel is the outermost surface on the viewer side of the image display device. The front panel is bonded via an adhesive layer.

[0090] Examples of front panels include glass and resin films with a hard coat layer on at least one surface. For example, high-transparency glass or tempered glass can be used as the glass. Chemically strengthened glass is preferred, especially when using thin transparent panels. The thickness of the glass can be, for example, 20 μm to 5 mm.

[0091] A front panel comprising a resin film with a hard coat layer on at least one surface can have flexible properties rather than being rigid like existing glass. The thickness of the hard coat layer is not particularly limited and may be, for example, 5 μm or more and 20 μm or less.

[0092] The resin film may be a film formed from polymers such as norbornene or polycyclic norbornene monomers containing monomer units of cycloolefins, cellulose (diacetylcellulose, triacetylcellulose, acetylcellulose butyrate, isobutyl ester cellulose, propionylcellulose, butyrylcellulose, acetylpropionylcellulose) ethylene-vinyl acetate copolymer, polycycloolefin, polyester, polystyrene, polyamide, polyetherimide, polyacrylic, polyimide, polyamideimide, polyethersulfone, polysulfone, polyethylene, polypropylene, polymethylpentene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl acetal, polyether ketone, polyetherether ketone, polyethersulfone, polymethyl methacrylate, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyurethane, epoxy, etc. The resin film can be unstretched, uniaxially oriented, or biaxially oriented. These polymers can be used individually or in mixtures of two or more. Preferred resin films include polyamide-imide films or polyimide films with excellent transparency and heat resistance, uniaxial or biaxially oriented polyester films, cycloolefin derivative films with excellent transparency and heat resistance that can accommodate larger film sizes, polymethyl methacrylate films, and triacetylcellulose and isobutyl ester cellulose films that are transparent and optically anisotropic. The thickness of the resin film may be 5 μm to 200 μm, preferably 20 μm to 100 μm.

[0093] The hard coat layer can be formed by curing a hard coat composition containing a reactive material that forms a crosslinked structure when irradiated with light or thermal energy. The hard coat composition may simultaneously contain a photocurable (meth)acrylate monomer or oligomer and a photocurable epoxy monomer or oligomer. The photocurable (meth)acrylate monomer may include one or more selected from the group consisting of epoxy (meth)acrylate, urethane (meth)acrylate, and polyester (meth)acrylate. Epoxy (meth)acrylate can be obtained by reacting an epoxy compound with a carboxylic acid having a (meth)acryloyl group.

[0094] The hard coat composition may further include one or more selected from the group consisting of solvents, photoinitiators, and additives. The additives may include one or more selected from the group consisting of inorganic nanoparticles, leveling agents, and stabilizers, and may further include components commonly used in the art, such as antioxidants, UV absorbers, surfactants, lubricants, and antifouling agents.

[0095] (Light-blocking pattern) The light-shielding pattern can be formed on the polarizer-side surface of the front panel. The light-shielding pattern can be formed on the frame (non-display area) of the image display device to prevent the wiring of the image display device from being visible to the user. The light-shielding pattern can be provided as at least a part of the front panel or the bezel or housing of the display device to which the front panel is applied. The color and material of the light-shielding pattern are not particularly limited and can be formed from a resin material having various colors such as black, white, and gold. In one embodiment, the thickness of the light-shielding pattern may be 2 μm or more and 50 μm or less, preferably 4 μm or more and 30 μm or less, and more preferably in the range of 6 μm or more and 15 μm or less. Furthermore, a shape can be given to the light-shielding pattern to suppress the inclusion of air bubbles due to the step between the light-shielding pattern and the display area and to suppress the visibility of the boundary.

[0096] The circular polarizer 200 shown in Figure 2 has, in this order, a protective film 14, an adhesive layer 13, a first optical anisotropy layer 11, an adhesive layer 15, a polarizer 10, an adhesive layer 18, and a second optical anisotropy layer 12.

[0097] The circular polarizer 300 shown in Figure 3 has, in this order, a first optical anisotropy layer 11, an adhesive layer 13, a linear polarizer 16 in which a protective film 14 and a polarizer 10 are laminated, an adhesive layer 15, and a second optical anisotropy layer 12. The adhesive layer that bonds the protective film 14 and the polarizer 10 is not shown.

[0098] The circular polarizer 400 shown in Figure 4 has, in this order, a protective film 14, an adhesive layer 13, a first optical anisotropy layer 11, an adhesive layer 15, a polarizer 10, an adhesive layer 18, a third optical anisotropy layer 17, and a second optical anisotropy layer 12. The adhesive layer bonding the third optical anisotropy layer 17 and the second optical anisotropy layer 12 is not shown.

[0099] The circular polarizer 500 shown in Figure 5 has, in this order, a first optical anisotropy layer 11, an adhesive layer 13, a linear polarizer 16 in which a protective film 14 and a polarizer 10 are laminated, an adhesive layer 15, a third optical anisotropy layer 17, and a second optical anisotropy layer 12. The adhesive layer that bonds the protective film 14 and the polarizer 10, and the adhesive layer that bonds the third optical anisotropy layer 17 and the second optical anisotropy layer 12 are not shown.

[0100] (Manufacturing method for circular polarizing plates) An example of a manufacturing method for the circular polarizer 300 will be described with reference to Figure 6. First, a second optical anisotropy layer 12 is laminated on the polarizer 10 side of the linear polarizer 16 via an adhesive layer 15 [Figure 6(a)]. Next, the circular polarizer 300 is obtained by laminating the first optical anisotropy layer 11 on the protective film 14 side of the linear polarizer 16 via an adhesive layer 13 [Figure 6(b)]. When the second optical anisotropy layer 12 includes an optical anisotropy layer having optical properties represented by formula (III), it is preferable to laminate the layers such that the angle between the absorption axis of the polarizer 10 and the slow axis of the second optical anisotropy layer 12 is 45°, and the angle between the slow axis of the first optical anisotropy layer 11 and the slow axis of the second optical anisotropy layer 12 is 90°.

[0101] A linear polarizing plate 16 can be manufactured by laminating a polarizer 10 and a protective film 14 with an adhesive layer in between. The linear polarizing plate 16 may also be manufactured by preparing a long piece of material, laminating the pieces together using a roll-to-roll method, and then cutting it into a predetermined shape, or by cutting the pieces into a predetermined shape and then laminating them together. After laminating the protective film to the polarizer, a heating process and a humidity control process may be included.

[0102] The first optical anisotropy layer 11 and the second optical anisotropy layer 12 can be manufactured, for example, as follows: An alignment film is formed on a substrate, and a coating solution containing a polymerizable liquid crystal compound is applied to the alignment film. With the polymerizable liquid crystal compound oriented, an active energy ray is irradiated to cure the polymerizable liquid crystal compound. An adhesive layer 15 formed on a release film is laminated onto the layer in which the polymerizable liquid crystal compound has been cured, and the substrate and / or alignment film are peeled off. The optically anisotropic layer may be manufactured by preparing long components, bonding them together using a roll-to-roll method, and then cutting them into a predetermined shape, or by cutting the components into a predetermined shape and then bonding them together. The release film is peeled off when bonding the optically anisotropic layer to the polarizer or linear polarizer, exposing the adhesive layer.

[0103] <Application> Circular polarizers can be used in a variety of display devices. A display device is a device having a display element, and includes a light-emitting element or light-emitting device as a light source. Examples of display devices include liquid crystal displays, organic EL displays, inorganic electroluminescent (hereinafter also referred to as inorganic EL) displays, electron emission displays (e.g., electric field emission displays (also referred to as FEDs), surface field emission displays (also referred to as SEDs)), electronic paper (display devices using electronic ink or electrophoretic elements, plasma displays, projection-type displays (e.g., grating light bulb (also referred to as GLV) displays, displays having digital micromirror devices (also referred to as DMDs)) and piezoelectric ceramic displays. Liquid crystal displays include transmissive liquid crystal displays and semi-transmissive liquid crystal displays. These display devices may be displays that display two-dimensional images or stereoscopic displays that display three-dimensional images. Circular polarizers can be used particularly effectively in organic EL displays or inorganic EL displays. The circular polarizing plate can be attached to a display element using an adhesive layer such that the first optical anisotropy layer faces the viewing side of the display device. The circular polarizing plate of the present invention is suitable for in-vehicle image display devices because it can reduce reflected light when in-vehicle display light is reflected off the windshield, reduce the color change of that reflected light, and has excellent light resistance.

[0104] In Figure 7, the organic EL display device 600 has a layered structure in which the organic EL display element 20 is laminated via an adhesive layer 19 laminated on the second optical anisotropy layer 12 side of the circular polarizing plate 101. The front plate 22 is bonded to the circular polarizing plate 101 via an adhesive layer 21 laminated on the first optical anisotropy layer 11. [Examples]

[0105] The present invention will be described in more detail below with reference to examples. In the examples, "%" and "parts" refer to mass%, and parts, respectively, unless otherwise specified.

[0106] [Evaluation of reflected light from display] As shown in FIG. 8, the display 23, the black acrylic plate 25, etc. were arranged. The obtained circular polarizing plate 24 was bonded to the viewing side (black acrylic plate 25 side) of the white display 23. The light emitted from the white display 23 was reflected by the black acrylic plate 25 installed so that the angle with respect to the display 23 was 45°. The display 23 was rotated horizontally with the axis 26 perpendicular to the display surface of the display 23 as the rotation axis, and the black acrylic plate 25 was visually observed from the observation direction 27. At this time, those with a small change in the color tone of the reflected light were evaluated as A, and those with a large change were evaluated as B.

[0107] [Evaluation of Circular Polarizing Plate Curl] An acrylic adhesive layer B and a separator film were bonded to the second optically anisotropic layer of the circular polarizing plate obtained in the example. The obtained circular polarizing plate with an adhesive was cut out to a size of 200 mm × 100 mm. The curl of the cut circular polarizing plate with an adhesive was evaluated. Those with curl were designated as B, and those without curl were designated as A.

[0108] [Evaluation of Light Resistance of Circular Polarizing Plate] An acrylic adhesive layer B and a separator film were bonded to the second optically anisotropic layer of the circular polarizing plate obtained in the example. The obtained circular polarizing plate with an adhesive was cut out to a size of 40 mm × 40 mm. The separator film was peeled off, and the exposed adhesive was bonded to non-alkali glass to obtain glass with a circular polarizing plate. The obtained sample was irradiated with a UV exposure amount of 95400 kJ / m 2 using a desktop xenon arc lamp type accelerated light resistance tester (manufactured by ATLAS, SUNTEST XLS+). The irradiation was performed from the first optically anisotropic layer side of the circular polarizing plate. The in-plane retardation values of the circular polarizing plate after irradiation with light of wavelengths 450 nm, 550 nm, and 650 nm were measured using KOBRA-WR manufactured by Oji Scientific Instruments Co., Ltd. ΔRe(550) of the second optically anisotropic layer was calculated from the obtained data. ΔRe(550) = Re(550) after the test - initial Re(550) [Evaluation Criteria] A: Those with ΔRe(550) smaller than that of Comparative Example 1 were considered to have good light resistance. B: ΔRe(550) values ​​equivalent to or greater than those of Comparative Example 1 were considered to indicate low lightfastness.

[0109] [Optical anisotropy layer A] A composition for forming an orientation film was obtained by mixing 5 parts of a photo-orienting material with the structure shown below (weight-average molecular weight: 30,000) with 95 parts of cyclopentanone (solvent), and stirring the resulting mixture at 80°C for 1 hour.

[0110] To 100 parts of a mixture of polymerizable liquid crystal compound a and polymerizable liquid crystal compound b shown below in a mass ratio of 90:10, 1.0 part of a leveling agent (F-556; manufactured by DIC Corporation) and 6 parts of a polymerization initiator, 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one ("Irg369," manufactured by BASF Japan Ltd.) were added.

[0111] Furthermore, N-methyl-2-pyrrolidone (NMP) was added to achieve a solid content concentration of 13%, and the mixture was stirred at 80°C for 1 hour to obtain a liquid crystal curing film formation composition.

[0112] Polymerizable liquid crystal compound a was produced by the method described in Japanese Patent Publication No. 2010-31223. Polymerizable liquid crystal compound b was produced according to the method described in Japanese Patent Publication No. 2009-173893. The molecular structures of each compound are shown below.

[0113] (Polymerizable liquid crystal compound a) [ka]

[0114] (Polymerizable liquid crystal compound b) [ka]

[0115] (Manufacturing of a laminate consisting of a substrate, an alignment film, and a layer of polymerizable liquid crystal compound that has been cured) A 50 μm thick cycloolefin film (product name "ZF-14-50" manufactured by Nippon Zeon Co., Ltd.) was subjected to corona treatment as a substrate. An alignment film-forming composition was applied to the corona-treated surface using a bar coater. The coated film was dried at 80°C for 1 minute. The dried coated film was irradiated with polarized UV light at an axis angle of 45° using a polarized UV irradiation device (product name "SPOT CURE SP-9" manufactured by Ushio Inc.) to obtain an alignment film. The polarized UV irradiation was performed with an integrated light amount of 100 mJ / cm² at a wavelength of 313 nm. 2 It was done in such a way.

[0116] Next, a liquid crystal curing film-forming composition was applied to the alignment film using a bar coater. The coated film was dried at 120°C for 1 minute. The dried coated film was irradiated with ultraviolet light using a high-pressure mercury lamp (product name: "UniCure VB-15201BY-A" from Ushio Inc.). The ultraviolet irradiation process involved an integrated light dose of 250 mJ / cm² at a wavelength of 365 nm. 2 The process was carried out under a nitrogen atmosphere. Immediately after irradiation, as a cooling step, the cured film was placed in an oven set to 5°C for 20 seconds. After removing it from the oven, the UV irradiation and cooling steps were immediately repeated to obtain a laminate consisting of a substrate, an alignment film, and a layer of polymerizable liquid crystal compound that had been cured.

[0117] (Measurement of phase difference value) An adhesive layer was laminated onto a cured layer of polymerizable liquid crystal compound in a laminate. The laminate was then bonded to glass via this adhesive layer. Subsequently, the substrate of the laminate was peeled off to obtain a sample for evaluating the phase difference value. As a result, the cured polymerizable liquid crystal compound layer had phase difference values ​​Re(λ) at each wavelength as follows: Re(450)=121nm, Re(550)=142nm, and Re(650)=146nm. Consequently, Re(450) / Re(550)=0.85 and Re(650) / Re(550)=1.03 were calculated. The cured polymerizable liquid crystal compound layer was a layer that provided a phase difference of λ / 4.

[0118] [Optical anisotropy layer B] A first optically anisotropic layer (H) [Re(550)=250nm] was fabricated as described in paragraphs 0026 to 0051 of Japanese Patent Publication No. 2015-187717.

[0119] [Optical anisotropy layer C] A second optical anisotropy layer (Q) [Re(550)=120nm] was fabricated as described in paragraphs 0053 to 0062 of Japanese Patent Publication No. 2015-187717.

[0120] [Optical anisotropy layer D] A stretched film made of norbornene-based resin with a thickness of 25 μm was prepared. When the phase difference values ​​were measured, Re(450) = 99.0 nm, Re(550) = 98.6 nm, and Re(650) = 98.5 nm, and the values ​​were calculated as Re(450) / Re(550) = 1.004 and Re(650) / Re(550) = 0.999.

[0121] [Optical anisotropy layer E] A polyvinyl alcohol film (0.1 μm thick) was formed on the surface of a substrate (TAC film, 40 μm thick). An oriented substrate was fabricated by rubbing the surface of the polyvinyl alcohol film with a rubbing cloth at a 45° angle to the longitudinal direction of the substrate.

[0122] A coating solution was prepared by dissolving 10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystal phase (BASF, trade name PaliocolorLC242) and 0.5 g of a photopolymerization initiator for the polymerizable liquid crystal compound (Ciba Specialty Chemicals, trade name Irgacure 907, containing 1% benzotriazole-based UV absorber) in 40 g of toluene.

[0123] The coating solution was applied to the surface of the oriented substrate obtained above using a bar coater, and then dried at 100°C for 1 minute. An optically anisotropic layer E was obtained by irradiating the coating film with ultraviolet light using a high-pressure mercury lamp. The ultraviolet irradiation was carried out under a nitrogen atmosphere, and the integrated light intensity at a wavelength of 365 nm was 1200 mJ / cm². 2The thickness of the obtained optically anisotropic layer E was measured using a laser microscope and found to be 973 nm. The orientation angle was 45° with respect to the longitudinal direction of the substrate. The phase difference values ​​of the optically anisotropic layer E were measured and found to be Re(450)=145 nm, Re(550)=135 nm, and Re(650)=132 nm. The relationship between the in-plane phase difference values ​​at each wavelength was as follows. Re(450) / Re(550)=1.07 Re(650) / Re(550)=0.98

[0124] [Linear polarizing plate A] A polarizer was prepared by adsorbing and oriented iodine onto a PVA-based resin. The thickness of this polarizer was 7 μm. A cycloolefin polymer (COP) film (ZF-14, manufactured by Nippon Zeon Co., Ltd.) was laminated to one side of the polarizer. The thickness of the COP film was 13 μm. In this way, a linear polarizer A was fabricated with a protective film on one side of the polarizer.

[0125] [Linear polarizer B] A polarizer-forming composition was prepared containing polymerizable liquid crystal compounds represented by the following formulas (1-6), polymerizable liquid crystal compounds represented by the following formulas (1-7), and azo dyes described in the examples of Japanese Patent Application Publication No. 2013-101328, represented by the following formulas (2-1a), (2-1b), and (2-3a). [ka] [ka] [ka] [ka] [ka]

[0126] An alignment film was formed on a substrate. A polarizing layer-forming composition was applied to the alignment film by a bar coating method. The coating film was irradiated with ultraviolet light to cure the polymerizable liquid crystal compound. In this way, a linear polarizing plate B was fabricated.

[0127] [Acrylic adhesive layer A] A sheet-type adhesive with a thickness of 5 μm (manufactured by Lintec Corporation) was prepared.

[0128] [Acrylic adhesive layer B] A sheet-type adhesive with a thickness of 25 μm (manufactured by Lintec Corporation) was prepared.

[0129] <Example 1> An acrylic adhesive layer A was bonded to the polarizer side of a linear polarizing plate A. The side of the optical anisotropy layer A with the cured polymerizable liquid crystal compound was bonded to the polarizer side via this adhesive layer so that the angle between the absorption axis of the polarizer and the slow phase axis of the optical anisotropy layer A (second optical anisotropy layer) was 45°. An acrylic adhesive layer A was bonded to the COP-side surface of the linear polarizing plate A. The side of the optical anisotropic layer A where the polymerizable liquid crystal compound had hardened was bonded to the second optical anisotropic layer via this adhesive layer such that the angle between the slow axis of the second optical anisotropic layer and the slow axis of optical anisotropic layer A (the first optical anisotropic layer) was 90°. In this way, a circular polarizer was fabricated comprising an optical anisotropy layer A (first optical anisotropy layer), a polarizer A, and an optical anisotropy layer A (second optical anisotropy layer) in this order.

[0130] <Example 2> An optically anisotropic layer laminate was fabricated by bonding optically anisotropic layer B (the third optically anisotropic layer) and optically anisotropic layer C (the second optically anisotropic layer) together with an acrylic adhesive layer A. In Example 1, instead of laminating the optical anisotropy layer A (second optical anisotropy layer) so that the angle between the absorption axis of the polarizer and the slow axis of the optical anisotropy layer A was 45°, a circular polarizer was fabricated in the same manner as in Example 1, except that the surface of the optical anisotropy layer laminate on the optical anisotropy layer B (third optical anisotropy layer) side and the polarizer side of the linear polarizer A were laminated via an acrylic adhesive layer A so that the angle between the absorption axis of the polarizer and the slow axis of the optical anisotropy layer C (second optical anisotropy layer) of the optical anisotropy layer laminate was 45°.

[0131] <Example 3> A circular polarizer was fabricated in the same manner as in Example 1, except that polarizer B was used instead of linear polarizer A.

[0132] <Example 4> A circular polarizing plate was fabricated in the same manner as in Example 1, except that the optical anisotropy layer A (first optical anisotropy layer) was laminated so that the angle between the slow axis of optical anisotropy layer A (second optical anisotropy layer) and the slow axis of optical anisotropy layer A (first optical anisotropy layer) was 0°.

[0133] <Comparative Example 1> A circular polarizing plate was fabricated in the same manner as in Example 1, except that optical anisotropy layer D was used instead of optical anisotropy layer A (the first optical anisotropy layer).

[0134] <Comparative Example 2> A circular polarizing plate was fabricated in the same manner as in Example 1, except that optical anisotropy layer E was used instead of optical anisotropy layer A (the first optical anisotropy layer).

[0135] [Table 1] [Explanation of symbols]

[0136] 10 Polarizer, 11 First optical anisotropy layer, 12 Second optical anisotropy layer, 13, 15, 18, 21 Adhesive layer, 19 Adhesive layer, 14 Protective film, 16 Linear polarizer, 17 Third optical anisotropy layer, 20 Organic EL display element, 22 Front panel, 23 Display, 24 Circular polarizer, 25 Black acrylic plate, 26 Axis, 27 Observation direction, 100, 101, 200, 300, 400, 500 Circular polarizer, 600 Organic EL display device.

Claims

1. A circular polarizer having, from the viewing side, a first optical anisotropy layer, a polarizer, and a second optical anisotropy layer in that order, The first optical anisotropy layer and the second optical anisotropy layer are given by the following formulas (I), (II), and (III): Re(450) / Re(550)≦1.00 (I) 1.00≦Re(650) / Re(550) (II) 90nm≦Re(550)≦180nm (III) [In the formula, Re(450) represents the in-plane phase difference value at a wavelength of 450 nm in the optically anisotropic layer.] Re(550) represents the in-plane phase difference value at a wavelength of 550 nm in the optically anisotropic layer. Re(650) represents the in-plane phase difference value at a wavelength of 650 nm in the optically anisotropic layer. It has optical properties represented by, The first optically anisotropic layer and the second optically anisotropic layer are layers containing polymers obtained by polymerizing polymerizable liquid crystal compounds in an oriented state. The first optical anisotropy layer and the second optical anisotropy layer are directly bonded to the polarizer or the linear polarizer plate including the polarizer and a protective film by an adhesive layer. A circular polarizer having a front plate on the side of the first optical anisotropy layer opposite to the polarizer (except in cases where two or more optical anisotropy layers are included on the viewing side of the polarizer).

2. Formula (IV): 200nm≦Re(550)≦320nm (IV) The circular polarizer according to claim 1, further comprising a third optical anisotropic layer having optical properties represented by the formula [wherein Re(550) represents the in-plane phase difference value at a wavelength of 550 nm of the optical anisotropic layer].

3. The circular polarizer according to claim 1 or 2, wherein the polarizer is a polarizer formed by adsorbing and oriented a dichroic dye on a uniaxially stretched polyvinyl alcohol-based resin film.

4. The circular polarizer according to claim 1 or 2, wherein the polarizer is a polarizer in which a dichroic dye is oriented in a cured film obtained by polymerizing a polymerizable liquid crystal compound.

5. An organic electroluminescent display device comprising a circular polarizer according to any one of claims 1 to 4.

6. An in-vehicle display comprising the organic electroluminescent display device described in claim 5.

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