Circular polarizing plate

Abstract

Provided is a circular polarizing plate capable of providing a display device that can operate stably even if the display device on which the circular polarizing plate is mounted is placed in a high-temperature environment, and even if the circular polarizing plate is shaped, perforated, or the like in the display device. The circular polarizing plate includes a first retardation plate including a thermoplastic resin layer having a glass transition temperature of 150 DEG C or more and a tensile modulus of elasticity of 3500 MPa or more, a polarizing plate including a layer of a cured product of a polymerizable liquid crystal composition, and a second retardation plate in this order, and the first retardation plate includes a thermoplastic resin layer having a glass transition temperature of 150 DEG C or more and a tensile modulus of elasticity of 3500 MPa or more. The first retardation plate includes a polymerizable liquid crystal composition including a polymerizable liquid crystal compound and a dichroic dye, and the second retardation plate includes a cured product layer of a polymerizable liquid crystal composition including a polymerizable liquid crystal compound.

Description

Technical Field

[0001] This invention relates to circular polarizing plates. Background Technology

[0002] In the past, circular polarizers were used to bond to image display elements such as liquid crystal cells or organic EL display elements in various image display panels (displays) such as liquid crystal display panels or organic electroluminescent (organic EL) display panels.

[0003] Devices that display images (such as display devices mounted in automobiles) are required to operate stably in high-temperature environments. Furthermore, as a technique for reducing changes in reflected color tone before and after placement in a high-temperature environment, for example, Patent Document 1 discloses a circular polarizer that, from the viewing side when assembled into a display device, sequentially includes a protective film A, a polarizer, a protective film B, and a phase retardation layer, wherein the protective film A is a cyclic olefin resin stretched film that displays the phase retardation.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2019-185007 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] In recent years, due to the diversification of display designs in display devices, it is sometimes necessary to shape or perforate circular polarizing plates. However, circular polarizing plates that have undergone such shaping or perforation sometimes cannot operate stably in high-temperature environments.

[0009] Therefore, the object of the present invention is to provide a circular polarizing plate that enables a display device to operate stably even when the display device equipped with the circular polarizing plate is placed in a high-temperature environment, and even when the circular polarizing plate is shaped or perforated in the display device.

[0010] Methods for solving problems

[0011] The inventors conducted in-depth research to solve the aforementioned problems. As a result, they discovered that the aforementioned problems could be solved by using a circular polarizing plate that sequentially comprises a specific first phase difference plate, a specific polarizing plate, and a specific second phase difference plate, thus completing the present invention.

[0012] That is, the present invention includes the following suitable embodiments.

[0013] [1] A circular polarizing plate, comprising, in sequence, a first phase difference plate, a polarizing plate, and a second phase difference plate.

[0014] The aforementioned first phase retardation plate comprises a thermoplastic resin layer having a glass transition temperature of 150°C or higher and a tensile modulus of elasticity of 3500 MPa or higher.

[0015] The aforementioned polarizing plate comprises a cured layer of a polymeric liquid crystal composition containing a polymeric liquid crystal compound and a dichroic pigment.

[0016] The aforementioned second phase retardation plate comprises a cured layer of a polymeric liquid crystal composition containing a polymeric liquid crystal compound.

[0017] [2] According to the circular polarizer described in [1], the phase difference Re1 (550) of the first phase difference plate at a wavelength of 550 nm and the phase difference Re2 (550) of the second phase difference plate at a wavelength of 550 nm satisfy the following equation (1):

[0018] Re1(550) < Re2(550) Equation (1).

[0019] [3] According to the circular polarizer described in [1] or [2], wherein the thermoplastic resin layer exhibits reverse wavelength dispersion.

[0020] [4] The circular polarizer described in any one of [1] to [3], wherein the first phase retardation plate comprises the thermoplastic resin layer and the phase retardation film, the phase retardation film exhibiting positive wavelength dispersion.

[0021] [5] A circular polarizing plate according to any one of [1] to [4], wherein the solidified layer contained in the second phase difference plate exhibits reverse wavelength dispersion.

[0022] [6] The circular polarizing plate described in any one of [1] to [5], wherein the side of the first phase difference plate opposite to the polarizing plate side further includes a cured resin layer.

[0023] [7] A circular polarizing plate according to any one of [1] to [6], wherein an irregularly shaped processing part is provided in the plane of the circular polarizing plate.

[0024] Invention Effects

[0025] According to the present invention, a circular polarizing plate can be provided, which enables a display device to operate stably even when the display device equipped with the circular polarizing plate is placed in a high-temperature environment, and even when the circular polarizing plate is shaped or perforated in the display device. Detailed Implementation

[0026] The embodiments of the present invention will now be described in detail. It should be noted that the scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the invention.

[0027] [Circular polarizing plate]

[0028] The circular polarizer of the present invention sequentially comprises a specific first phase retardation plate, a specific polarizer plate, and a specific second phase retardation plate. The inventors have discovered that, surprisingly, by giving the circular polarizer the aforementioned specific configuration, when the circular polarizer of the present invention is applied to a display device, the display device can operate stably even when the display device is placed in a high-temperature environment, and even when the circular polarizer plate in the display device has undergone shape processing or perforation.

[0029] <First Phase Difference Plate>

[0030] Throughout this specification, "phase reversal plate" refers to a film containing a phase reversal film or phase reversal membrane, and is a film that exhibits the optical function of such a phase reversal film or phase reversal membrane. A "phase reversal film" is a film that displays a phase difference in the in-plane or thickness direction, and this phase difference is formed by stretching a thermoplastic resin film, etc. A "phase reversal membrane" (liquid crystal phase reversal membrane) refers to a film that displays a phase difference in the in-plane or thickness direction; it is a single layer made of a polymer containing a polymeric liquid crystal compound, or a layer consisting of this layer and an alignment film.

[0031] The first retardation plate comprises a thermoplastic resin layer having a glass transition temperature of 150°C or higher and a tensile modulus of elasticity of 3500 MPa or higher. When the thermoplastic resin layer is a retardation film, the first retardation plate includes the thermoplastic resin layer as a layer that manifests the retardation. When the thermoplastic resin layer is not a retardation film, the first retardation plate includes, in addition to the thermoplastic resin layer (which does not manifest the retardation), a retardation film as a layer that manifests the retardation. Therefore, when the thermoplastic resin layer is a retardation film, the first retardation plate can be a single layer composed of the thermoplastic resin layer or a multilayer composed of the thermoplastic resin layer and other layers; when the thermoplastic resin layer is not a retardation film, the first retardation plate can be a multilayer comprising the thermoplastic resin layer and a retardation film.

[0032] The glass transition temperature of the thermoplastic resin layer is 150°C or higher, preferably 155°C or higher, and more preferably 160°C or higher. If the glass transition temperature of the thermoplastic resin layer is above the aforementioned lower limit, the retardation plate can exhibit superior heat resistance, thus enabling the display device assembled with a circular polarizer including the retardation plate to operate stably even in harsh environments. The upper limit of the glass transition temperature of the thermoplastic resin layer is not particularly limited, and is typically below 200°C. The glass transition temperature of the thermoplastic resin layer can be adjusted to be above the aforementioned lower limit, or above the aforementioned lower limit and below the aforementioned upper limit, by appropriately selecting the composition of the composition forming the thermoplastic resin layer. The glass transition temperature of the thermoplastic resin layer can be measured using a differential scanning calorimeter (DSC), specifically, by the method described in the examples described later.

[0033] The tensile modulus of elasticity of the thermoplastic resin layer is 3500 MPa or more, preferably 3600 MPa or more, and more preferably 3700 MPa or more. If the tensile modulus of elasticity of the thermoplastic resin layer is above the aforementioned lower limit, the retardation plate can exhibit lower stress and strain even under high-temperature conditions, thus enabling the display device equipped with a circular polarizer including the retardation plate to operate stably even in harsh environments. The upper limit of the tensile modulus of elasticity of the thermoplastic resin layer is not particularly limited, and is typically 5000 MPa or less. The tensile modulus of elasticity of the thermoplastic resin layer can be adjusted to be above the aforementioned lower limit, or above the aforementioned lower limit and below the aforementioned upper limit, by appropriately selecting the composition of the composition forming the thermoplastic resin layer. The tensile modulus of elasticity of the thermoplastic resin layer can be measured using a precision universal testing machine, specifically by the method described in the examples described later.

[0034] In order for the first phase difference plate to function as a phase difference plate, the first phase difference plate preferably has a phase difference value that satisfies the following equations (2) to (4):

[0035] 90nm≤Re1(450)≤130nm (2)

[0036] 85nm≤Re1(550)≤120nm (3)

[0037] 80nm≤Re1(650)≤110nm (4)

[0038] [In equations (2) to (4), Re1(λ) represents the in-plane phase difference value of the first phase difference plate at wavelength λnm].

[0039] If the in-plane phase difference Re1(λ) of the first phase difference plate is within the range of equations (2) to (4), then the first phase difference plate becomes a phase difference plate that functions as a 1 / 4 wavelength plate. When a circular polarizer containing the first phase difference plate is applied to a display device, the visibility of the display device can be improved even if the display device is placed in a high-temperature environment, and even if the circular polarizer in the display device is shaped or perforated. It should be noted that in this specification, the in-plane phase difference value is measured at a temperature of 23°C and a relative humidity of 55%. The further preferred ranges of the above-mentioned in-plane phase difference value are 95nm≤Re1(450)≤110nm, 85nm≤Re1(550)≤105nm, and 85nm≤Re1(650)≤105nm.

[0040] In the first phase retardation plate, when the thermoplastic resin layer has a phase difference, the thermoplastic resin layer is preferably a stretched thermoplastic resin film. The in-plane phase difference of the first phase retardation plate can then be adjusted to the aforementioned range by the stretching ratio and / or thickness of the thermoplastic resin film, and / or wavelength dispersion.

[0041] In the first retardation plate, where the thermoplastic resin layer does not have a phase difference but the retardation film does, the retardation film is a single layer made of a polymer containing a polymeric liquid crystal compound, or a layer composed of the single layer and an alignment film. In this case, the in-plane phase difference of the first retardation plate can be adjusted to the aforementioned range by the thickness of the retardation film and / or birefringence.

[0042] In one embodiment of the invention, the first retardation plate preferably does not contain a stretched thermoplastic resin film. By omitting the stretched thermoplastic resin film from the first retardation plate, the crack resistance of the circular polarizer in the invention can be improved. In this embodiment, the first retardation plate may contain a thermoplastic resin layer without phase difference and a retardation film.

[0043] From the viewpoint of desired phase difference and thinness, the thickness of the first phase difference plate is preferably 3 to 30 μm, more preferably 5 to 25 μm. In this invention, the thickness of each layer or film can be measured by conventional methods in this art, such as using a laser microscope, film thickness gauge, ellipsometer, etc.

[0044] (Thermoplastic resin layer)

[0045] When the thermoplastic resin layer contained in the first phase difference plate has a phase difference, the thermoplastic resin layer is preferably a stretched thermoplastic resin film.

[0046] The thermoplastic resin contained in the stretched thermoplastic resin film is not particularly limited as long as the thermoplastic resin layer has a glass transition temperature of 150°C or higher and a tensile modulus of elasticity of 3500 MPa or higher. The stretched thermoplastic resin film preferably contains two or more of the following as resin components: chain polyolefin resin, cyclic polyolefin resin, polycarbonate resin, cellulose resin, cellulose ester resin, polyester resin, (meth)acrylic resin, etc. More preferably, the resin component of the stretched thermoplastic resin film contains one or more of the following.

[0047] Examples of chain polyolefin resins include homopolymers of chain olefins such as polyethylene resin and polypropylene resin, as well as copolymers composed of two or more chain olefins.

[0048] Cyclic polyolefin resins are a general term for resins polymerized using cyclic olefins as polymeric units. Examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic olefins, addition polymers of cyclic olefins, copolymers of cyclic olefins with chain olefins such as ethylene or propylene (typically random copolymers), graft polymers modified with unsaturated carboxylic acids or their derivatives, and their hydrides. From the viewpoint of the glass transition temperature and tensile modulus of elasticity of thermoplastic resin layers, norbornene-based resins using norbornene monomers or polycyclic norbornene monomers as cyclic olefins are preferred.

[0049] Polycarbonate resins are polymers composed of monomer units bonded together via carbonate groups. Polycarbonate resins can be modified polycarbonates (where the polymer backbone is modified), copolymer polycarbonates, etc.

[0050] Examples of cellulose-based resins include cellulose triacetate and cellulose diacetate.

[0051] Cellulose ester resins are esters of cellulose and fatty acids. Examples of cellulose ester resins include cellulose triacetate (TAC), cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Additionally, copolymers of these resins and substances modified by other substituents on a portion of the hydroxyl groups can also be used. From a mechanical property point of view, cellulose triacetate is particularly preferred.

[0052] Polyester resins are resins containing ester bonds, typically composed of polycarboxylic acids or their derivatives and polyols. As polycarboxylic acids or their derivatives, dicarboxylic acids or their derivatives can be used; specific examples include terephthalic acid, isophthalic acid, dimethyl terephthalate, and dimethyl naphthalate. As polyols, diglycols can be used; specific examples include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and cyclohexanediol.

[0053] Specific examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polypropylene terephthalate, polycyclohexanedimethyl terephthalate, and polycyclohexanedimethyl terephthalate.

[0054] (Meth)acrylic resins are resins whose main monomers are compounds having (meth)acryloyl groups. Specific examples of (meth)acrylic resins include poly(meth)acrylates such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymers; methyl methacrylate-(meth)acrylate copolymers; methyl methacrylate-acrylate-(meth)acrylic acid copolymers; methyl methacrylate-styrene copolymers (MS resin, etc.); and copolymers of methyl methacrylate with compounds having alicyclic hydrocarbon groups (e.g., methyl methacrylate-cyclohexyl methacrylate copolymers, methyl methacrylate-norborneol ester copolymers, etc.). It is preferable to use poly(meth)acrylates such as poly(meth)acrylic acid C... 1～6 The polymer is mainly composed of alkyl esters, and more preferably, a methyl methacrylate resin is mainly composed of methyl methacrylate (50-100% by weight, preferably 70-100% by weight).

[0055] In addition to the aforementioned thermoplastic resin, the thermoplastic resin layer may optionally contain additives. Examples of such additives include antioxidants, mold release agents, stabilizers, bluing agents, flame retardants, pH adjusters, silica dispersants, lubricants, thickeners, leveling agents, and combinations of two or more thereof. When the thermoplastic resin layer contains additives, their amount relative to the total mass of the thermoplastic resin layer is preferably 0.001 to 20% by mass, more preferably 0.01 to 15% by mass, and even more preferably 0.1 to 10% by mass.

[0056] From the viewpoint of the desired phase difference value, the stretching ratio of the stretched thermoplastic resin film is preferably 1 to 5 times, more preferably 1 to 3 times, and even more preferably 1 to 2 times.

[0057] From the viewpoint of desired phase difference value and thinness, the thickness of the thermoplastic resin layer contained in the first phase difference plate when the phase difference is present is preferably 3 to 30 μm, more preferably 5 to 28 μm.

[0058] When the thermoplastic resin layer contained in the first phase difference plate has a phase difference, the thermoplastic resin layer preferably exhibits inverse wavelength dispersion. Inverse wavelength dispersion is an optical characteristic in which the in-plane phase difference value at a short wavelength is smaller than the in-plane phase difference value at a long wavelength, and the thermoplastic resin layer preferably satisfies the following equations (5) and (6). It should be noted that Re1(λ) represents the in-plane phase difference value for light with a wavelength of λnm.

[0059] Re1(450) / Re1(550)<1.00(5)

[0060] 1.00<Re1(650) / Re1(550) (6)

[0061] By making the thermoplastic resin layer exhibit reverse wavelength dispersion, the visibility of the display device can be further improved even when the circular polarizer containing the first phase difference plate is applied to the display device, even if the display device is placed in a high-temperature environment, and even if the circular polarizer is shaped or perforated in the display device.

[0062] From the viewpoint that improving the inverse wavelength dispersion can further enhance the visibility of the aforementioned display device, Re1(450) / Re1(550) is preferably 0.70 or higher, more preferably 0.80 or higher, even more preferably 0.90 or higher, and preferably 0.99 or lower. Furthermore, Re1(650) / Re1(550) is preferably 1.01 or higher, and preferably 1.20 or lower, more preferably 1.15 or lower, and even more preferably 1.10 or lower.

[0063] The values ​​of Re1(450) / Re1(550) and Re1(650) / Re1(550) can be adjusted to be above the lower limit and below the upper limit by means of the elongation and / or thickness of the thermoplastic resin film and / or wavelength dispersion.

[0064] Therefore, in this embodiment, the first phase difference plate preferably comprises a thermoplastic resin layer having a phase difference, the thermoplastic resin layer exhibiting inverse wavelength dispersion.

[0065] When the thermoplastic resin layer contained in the first phase difference plate does not have a phase difference, the thermoplastic resin layer is preferably a film equivalent to the thermoplastic resin film before stretching of the above-described stretched thermoplastic resin film.

[0066] From the viewpoint of thinness and / or protection, the thickness of the thermoplastic resin layer contained in the first phase difference plate when it does not have a phase difference is preferably 3 to 30 μm, more preferably 5 to 28 μm.

[0067] There are no particular limitations on the manufacturing method of thermoplastic resin films and stretched thermoplastic resin films; they can be manufactured by known methods.

[0068] (Phase difference film)

[0069] In one embodiment where the thermoplastic resin layer contained in the first retardation plate does not have a phase difference, the first retardation plate includes a retardation film. The retardation film is a single layer made of a polymer containing a polymeric liquid crystal compound, or a layer consisting of the single layer and an alignment film.

[0070] From the viewpoint of phase retardation functionality and thinness, the thickness of the phase retardation film is preferably 0.1–5 μm, more preferably 0.5–5 μm, even more preferably 0.5–3 μm, and even more preferably 1–3 μm. When the phase retardation film includes an alignment film, the thickness of the alignment film is not included in the above-mentioned thickness.

[0071] The retardation film is preferably a "horizontally oriented liquid crystal cured film" formed by curing a polymeric liquid crystal compound in a state of horizontal orientation relative to the plane of the retardation film. The retardation film preferably satisfies the above formulas (7) to (9).

[0072] The retardation film can also be a retardation film serving as a positive C-plate (nx≈ny<nz), or a retardation film functioning as a half-wavelength plate. The retardation film serving as a positive C-plate is a "vertically oriented liquid crystal cured film" formed by curing a polymeric liquid crystal compound in a state of vertical orientation relative to the plane of the retardation film. The circular polarizer of the present invention combines a retardation film functioning as a quarter-wavelength plate and a retardation film serving as a positive C-plate as a first retardation plate and a second retardation plate. Therefore, when this circular polarizer is applied to organic EL display devices, etc., in addition to improving the front reflection color tone, it is also expected to improve the oblique reflection color tone.

[0073] The polymeric liquid crystal compound capable of forming a retardation film in this invention can be appropriately selected from polymeric liquid crystal compounds conventionally known in the field of retardation films, depending on the desired optical properties. The polymeric liquid crystal compounds that can be used in this invention can be classified, for example, according to their shape, as rod-shaped (rod-shaped liquid crystal compounds) and disk-shaped (disc-shaped liquid crystal compounds, disc-shaped liquid crystal compounds), or any single liquid crystal compound can be used. Furthermore, two or more rod-shaped liquid crystal compounds, two or more disk-shaped liquid crystal compounds, or a mixture of rod-shaped and disk-shaped liquid crystal compounds can be used.

[0074] Polymerizable liquid crystal compounds are liquid crystal compounds having polymerizable groups. Examples of polymerizable liquid crystal compounds (cured products) obtained by polymerizing the polymerizable liquid crystal compound individually in a state of orientation along a specific direction include polymerizable liquid crystal compounds exhibiting positive wavelength dispersion and polymerizable liquid crystal compounds exhibiting reverse wavelength dispersion. In this invention, either one polymerizable liquid crystal compound may be used alone, or two polymerizable liquid crystal compounds may be used in combination.

[0075] In this invention, the polymerizable groups in the polymerizable liquid crystal compound forming the phase retardation film are preferably photopolymerizable groups. Photopolymerizable groups refer to groups that can participate in polymerization reactions through active free radicals, acids, etc., generated by a polymerization initiator. Examples of polymerizable groups in the polymerizable liquid crystal compound include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, acryloyloxy, methacryloyloxy, ethylene oxide, and oxetyl. Among these, free radical polymerizable groups are preferred, acryloyloxy, methacryloyloxy, vinyloxy, ethylene oxide, and oxetyl are more preferred, and acryloyloxy or methacryloyloxy is even more preferred. The liquid crystal properties exhibited by the polymerizable liquid crystal compound can be thermotropic or lyotropic, but from the perspective of enabling dense film thickness control, thermotropic liquid crystals are preferred. Furthermore, the phase sequence structure in the thermotropic liquid crystal can be nematic liquid crystal, smectic liquid crystal, or discoid liquid crystal. Two or more polymerizable liquid crystal compounds can be used alone or in combination.

[0076] The aforementioned phase difference film preferably satisfies the following equation (7):

[0077] 85nm≤Re1(550)≤120nm (7)

[0078] [In the formula, Re(λ)1 represents the in-plane phase difference value of the phase difference film at wavelength λnm].

[0079] If the in-plane phase difference Re1 (550) of the retardation film is within the range of Equation (7), then the retardation film functions as a 1 / 4 wavelength plate. When a circular polarizer containing this retardation film is applied to a display device, even if the display device is placed in a high-temperature environment, and even if the circular polarizer is shaped or perforated in the display device, the visibility of the display device can be further improved. A further preferred range for the in-plane phase difference value is 85nm ≤ Re1 (550) ≤ 105nm.

[0080] The retardation film preferably exhibits positive wavelength dispersion. Positive wavelength dispersion refers to the optical characteristic that the in-plane phase difference at a longer wavelength is less than the in-plane phase difference at a shorter wavelength. The retardation film preferably satisfies the following equations (8) and (9).

[0081] Re1(450) / Re1(550)≥1.00(8)

[0082] 1.00≥Re1(650) / Re1(550) (9)

[0083] By enabling the phase retardation film to exhibit positive wavelength dispersion, when a circular polarizer containing the first phase retardation plate is applied to a display device, especially when the first phase retardation plate is positioned closer to the observation side than the second phase retardation plate, the visibility of the display device can be further improved even when the display device is placed in a high-temperature environment, and even when the circular polarizer plate in the display device has undergone shape processing or perforation.

[0084] From the viewpoint that improving the positive wavelength dispersion can further enhance the visibility of the aforementioned display device, Re1(450) / Re1(550) is preferably 1.30 or less, more preferably 1.20 or less, even more preferably 1.10 or less, and preferably 1.01 or more. Furthermore, Re1(650) / Re1(550) is 0.90 or more, more preferably 0.92 or more, and even more preferably 0.94 or more.

[0085] The values ​​of Re1(450) / Re1(550) and Re1(650) / Re1(550) can be adjusted to be above the lower limit and below the upper limit by means of the inherent birefringence of the resin material used.

[0086] Therefore, in this embodiment, the first retardation plate preferably comprises a thermoplastic resin layer without retardation and a retardation film that exhibits positive wavelength dispersion.

[0087] The aforementioned in-plane phase difference value can be adjusted by the film thickness dA of the phase difference film. The in-plane phase difference value is determined according to the following formula:

[0088] ReA(λ)=(nxA(λ)-nyA(λ))×dA

[0089] [In the formula, nxA(λ) represents the principal refractive index at wavelength λnm in the plane of the retardation film, nyA(λ) represents the refractive index at wavelength λnm in the direction orthogonal to the direction of nxA in the same plane as nxA, and dA represents the film thickness of the retardation film.]

[0090] Therefore, in order to obtain the desired in-plane phase difference value (ReA(λ): the in-plane phase difference value of the phase difference film at wavelength λ(nm), the three-dimensional refractive index and film thickness dA can be adjusted.

[0091] As an example of a polymeric liquid crystal compound that produces a phase reversal film with positive wavelength dispersion, one could cite "Paliocolor (registered trademark) LC242" manufactured by BASF Japan.

[0092] Provided that the effects of the present invention are not impaired, the polymeric liquid crystal composition used to form the retardation film (hereinafter also referred to as the "composition for forming the retardation film") may also contain polymeric liquid crystal compounds other than those that provide positive wavelength dispersion. When the composition for forming the retardation film contains two or more polymeric liquid crystal compounds, from the viewpoint of obtaining a retardation film with excellent optical properties, it is preferable that at least one of them is a polymeric liquid crystal compound that provides positive wavelength dispersion, or all of the polymeric liquid crystal compounds contained in the composition for forming the retardation film may be polymeric liquid crystal compounds that provide positive wavelength dispersion.

[0093] The content of the polymeric liquid crystal compound that imparts positive wavelength dispersion in the phase retardation film forming composition is preferably 60 to 99.9% by mass, more preferably 70 to 99.9% by mass, and even more preferably 80 to 99% by mass, relative to the solid content of the composition. If the content of the polymeric liquid crystal compound is within the above range, there is a tendency for the orientation of the polymeric liquid crystal compound to increase. In this specification, solid content refers to the total amount of components after removing the solvent from the phase retardation layer forming composition. Hereinafter, when referred to as solid content in this specification, it also refers to the component after removing volatile components such as solvents from the composition in question.

[0094] The composition for forming a phase retardation film may include a polymerization initiator for initiating a polymerization reaction of a polymerizable liquid crystal compound. As the polymerization initiator, it can be appropriately selected from polymerization initiators conventionally used in the field, including thermal polymerization initiators and photopolymerization initiators. Photopolymerization initiators are preferred from the perspective of being able to initiate polymerization reactions at lower temperatures. The polymerization initiator can be used alone or in combination of two or more.

[0095] As photopolymerization initiators, known photopolymerization initiators can be used, such as self-destructive photopolymerization initiators and hydrogen-abstracting photopolymerization initiators that generate active free radicals.

[0096] As self-destructive photopolymerization initiators, self-destructive compounds such as benzoin, acetophenone, hydroxyacetophenone, α-aminoacetophenone, oxime esters, acylphosphine oxides, and azo compounds can be used. Additionally, as hydrogen-abstraction photopolymerization initiators, hydrogen-abstraction compounds such as benzophenone, benzoin ethers, benzoylacetyl ketals, dibenzocycloheptanone, anthraquinones, xanthones, thioxanthones, haloacetophenones, dialkoxyacetophenones, halodiimidazoles, halotriazines, and triazines can be used.

[0097] Iodonium salts and matte salts can be used as photopolymerization initiators that generate acids.

[0098] From the viewpoint of preventing pigment dissolution, a reaction at low temperature is preferred. From the viewpoint of reaction efficiency at low temperature, a self-destructive photopolymerization initiator is preferred, and acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, and oxime ester compounds are particularly preferred.

[0099] Specifically, the following substances can be cited as photopolymerization initiators.

[0100] Benzoin compounds, such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether;

[0101] Oligomers of 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1,2-diphenyl-2,2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propane-1-one, 1-hydroxycyclohexylphenyl one and oligomers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane-1-one, etc., are hydroxyacetophenone compounds.

[0102] α-aminoacetophenone compounds such as 2-methyl-2-morpholino-1-(4-methylthiophenyl)propane-1-one and 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butane-1-one;

[0103] 1,2-Octanedione, 1-[4-(phenylthio)-,2-(O-benzoyl oxime)], acetone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]-,1-(O-acetyl oxime) and other oxime ester compounds;

[0104] Acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyl diphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide;

[0105] Benzophenone, methyl phthalobenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyl diphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone and 2,4,6-trimethylbenzophenone and other benzophenone compounds;

[0106] Diethoxyacetophenone and other diekoxyacetophenone compounds;

[0107] 2,4-Bis(trichloromethyl)-6-(4-methoxyphenyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxynaphthyl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-(4-methoxystyryl)-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)vinyl]-1,3,5 Triazine compounds, including 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)vinyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)vinyl]-1,3,5-triazine, and 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)vinyl]-1,3,5-triazine.

[0108] The photopolymerization initiator can be appropriately selected from the aforementioned photopolymerization initiators in relation to the polymerizable liquid crystal compound that forms the phase retardation film.

[0109] Alternatively, commercially available photopolymerization initiators can be used. Commercially available polymerization initiators include: Irgacure (イルガキュア) (registered trademark) 907, 184, 651, 819, 250 and 369, 379, 127, 754, OXE01, OXE02, OXE03 (manufactured by BASF); Omnirad BCIM, Esacure 1001M, Esacure KIP160 (manufactured by IDM Resins BV); SEIKUOL (registered trademark) BZ, Z and BEE (manufactured by Seiko Chemical Co., Ltd.); kayacure (カヤキュアー) (registered trademark) BP100 and VUI-6992 (manufactured by Dow Chemical Co., Ltd.); ADEKA Optomer SP-152, N-1717, N-1919, SP-170, and ADEKA ARKLS. NCI-831, ADEKA ARKLS NCI-930 (manufactured by ADEKA Co., Ltd.); TAZ-A and TAZ-PP (manufactured by NIHON SIBER HEGNER Co., Ltd.); and TAZ-104 (manufactured by SANWACHEMICAL Co., Ltd.), etc.

[0110] The composition for forming a phase retardation film may contain, as needed, leveling agents, polymerizable non-liquid crystal compounds, photosensitizers, antioxidants, release agents, stabilizers, colorants such as bluing agents, flame retardants, and lubricants, as well as other additives. When such additives are present, their content relative to the solid content of the composition for forming a phase retardation film is preferably more than 0% and less than 20% by mass, more preferably more than 0% and less than 10% by mass.

[0111] Leveling agents have the function of adjusting the flowability of the composition for forming phase difference films and making the coating obtained by applying the composition smoother. Specifically, surfactants can be cited as examples. As a leveling agent, at least one selected from leveling agents mainly composed of polyacrylate compounds and leveling agents mainly composed of fluorine-containing compounds is preferred. Leveling agents can be used alone or in combination of two or more.

[0112] Examples of leveling agents that are mainly composed of polyacrylate compounds include BYK-350, BYK-352, BYK-353, BYK-354, BYK-355, BYK-358N, BYK-361N, BYK-380, BYK-381 and BYK-392 (BYK Chemie).

[0113] Examples of leveling agents whose main component is a compound containing fluorine atoms include Megaface (registered trademark) R-08, R-30, R-90, F-410, F-411, F-443, F-445, F-470, F-471, F-477, F-479, F-482, F-483, and F-556 (DIC Corporation); Surflon (registered trademark) S-381, S-382, S-383, S-393, SC-101, SC-105, KH-40, and SA-100 (AGC Seimi Chemical Co., Ltd.); E1830 and E5844 (Daikin FineChemical Research Institute, Ltd.); Eftop EF301, Eftop EF303, Eftop EF351, and Eftop EF352 (Mitsubishi Materials Electronic Chemicals Co., Ltd.).

[0114] When the composition for forming the retardation film contains a leveling agent, its content is preferably 0.01 to 5 parts by mass relative to 100 parts by mass of the polymeric liquid crystal compound, more preferably 0.05 to 3 parts by mass. If the content of the leveling agent is within the above range, there is a tendency to easily orient the polymeric liquid crystal compound and avoid unevenness, resulting in a smoother retardation film.

[0115] The composition for forming a phase retardation film can be prepared, for example, by mixing and stirring a polymerizable liquid crystal compound with a desired polymerization initiator, additives, etc. Furthermore, to improve coatability, a solvent can be added to the composition for forming the phase retardation film to adjust the viscosity. As solvents, examples include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropanol, propylene glycol, ethylene glycol methyl ether, ethylene glycol butyl ether, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone or propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-containing solvents such as chloroform and chlorobenzene; amide solvents such as N,N-dimethylacetamide and N,N-dimethylformamide; sulfur-containing solvents such as dimethyl sulfone, dimethyl sulfoxide, and sulfolane; carbonate solvents such as ethylene carbonate and propylene carbonate; and pyrrolidone solvents such as N-methylpyrrolidone. These solvents can be used alone or in combination of two or more.

[0116] The solvent content is preferably 100 to 1900 parts by mass relative to 100 parts by mass of the solid component of the composition for forming the phase difference film, more preferably 150 to 1000 parts by mass, and even more preferably 180 to 800 parts by mass.

[0117] Phase retardation films can be obtained by coating a phase retardation film forming composition onto a substrate or an alignment film, removing the solvent by drying, and curing the polymeric liquid crystal compound in the resulting coating film in an aligned state.

[0118] Without subsequently peeling off the substrate, the substrate is equivalent to the aforementioned thermoplastic resin layer without phase difference. Therefore, the substrate is preferably the same as the thermoplastic resin film before stretching of the aforementioned stretched thermoplastic resin film. Alternatively, a commercially available thermoplastic resin film having a glass transition temperature of 150°C or higher and a tensile modulus of elasticity of 3500 MPa or higher can be used as the substrate. Surface treatments such as corona treatment and plasma treatment can be applied to the substrate.

[0119] In cases where the substrate is subsequently peeled off, in addition to the aforementioned substrates that can be used without peeling off the substrate, conventionally known resin film substrates in the field of optical films can also be used as the substrate. Specifically, examples of resins constituting such conventionally known resin films include, for instance, polyolefin resins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene polymers; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; poly(meth)acrylic acid and poly(meth)acrylate resins such as methyl methacrylate; cellulose ester resins such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; vinyl alcohol resins such as polyvinyl alcohol and polyvinyl acetate; polycarbonate resins; polystyrene resins; polyaryl ester resins; polysulfone resins; polyethersulfone resins; polyamide resins; polyimide resins; polyetherketone resins; polyphenylene sulfide resins; polyphenylene ether resins; and mixtures thereof. These can be used individually or in combination of two or more. Such resins can be used to form resin film substrates through known methods such as solvent casting and melt extrusion. Furthermore, commercially available resins can be used as the film substrate or as components of the film substrate. For subsequent peeling of the substrate, it is preferable to perform a demolding treatment on the substrate.

[0120] After the substrate is subsequently peeled off, by bonding the retardation film with a thermoplastic resin film identical to that used in the case where the substrate is not subsequently peeled off, a laminate comprising the retardation film and a thermoplastic resin layer having a specified glass transition temperature and tensile modulus can be obtained. The bonding of the retardation film to the thermoplastic resin layer can be performed, for example, via an adhesive bonding layer.

[0121] The bonding layer is a layer formed by an adhesive. This bonding layer is not particularly limited as long as it functions as a layer for bonding a phase retardation film to a thermoplastic resin layer having a specified glass transition temperature and tensile modulus; it can be a layer formed by a known adhesive. There are no particular limitations on the adhesive or bonding agent; conventionally known adhesives and bonding agents can be used without particular restriction. Examples of adhesives include those with acrylic, rubber, urethane, silicone, or polyvinyl ether base polymers. Additionally, energy-curing adhesives and thermosetting adhesives can also be used. Examples of adhesives include active energy-curing adhesives, water-based adhesives, organic solvent-based adhesives, and solvent-free adhesives.

[0122] In one embodiment of the present invention, an adhesive is preferably used as the bonding agent for bonding the retardation film to a thermoplastic resin layer having a specified glass transition temperature and tensile modulus. Using an adhesive as the bonding agent for bonding the retardation film to the thermoplastic resin layer having a specified glass transition temperature and tensile modulus improves the crack resistance of the circular polarizer of the present invention and reduces the reflectivity in the display device. When assembling the circular polarizer of the present invention into a display device, the reflectivity reduction effect is further enhanced when the first retardation plate is positioned closer to the observation side than the second retardation plate. The reflectivity can be evaluated using the methods described in the embodiments described later.

[0123] From the viewpoint of sufficient bonding strength between adjacent layers and the thinness of the circular polarizer, the thickness of the bonding layer is preferably 1 to 10 μm, more preferably 1.5 to 8 μm.

[0124] There are no particular limitations on the thickness of the substrate; any suitable thickness within a practical range can be selected. For example, it can be approximately 5μm to 300μm.

[0125] The aforementioned retardation film may include an alignment film. The alignment film possesses an orientation-restricting force that orients the polymerizable liquid crystal compound in a desired direction. By coating the retardation film forming composition onto the alignment film, a retardation film (cured layer) with excellent orientation precision can be easily obtained. Preferably, the alignment film possesses solvent resistance that prevents dissolution due to coating of the aforementioned retardation film forming composition, and also possesses heat resistance during heat treatment for solvent removal and orientation of the polymerizable liquid crystal compound. Furthermore, it is preferable to have a small difference in refractive index with the retardation film or the bonding layer.

[0126] Examples of orientation films include orientation films containing orientation polymers, photo-oriented films, grooved orientation films with raised or recessed patterns or multiple grooves on the surface, and stretched films stretched along the orientation direction. These various orientation films can be appropriately selected from those conventionally known in the field based on the desired orientation restraint force.

[0127] In one embodiment of the invention, a photoalignment film is preferred from the viewpoints of improving alignment accuracy and ensuring good adhesion to the cured layer formed by the phase retardation film forming composition. The photoalignment film is also advantageous because the direction of the alignment restraint force can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light.

[0128] Photoalignment films are typically obtained by coating a composition (hereinafter also referred to as a "photoalignment film forming composition") containing a polymer, oligomer, or monomer having photoreactive groups and a solvent onto a substrate or the like, and then irradiating it with polarized light (preferably polarized UV light). If the polymer or the like contained in the photoalignment film forming composition has the same reactive groups (e.g., (meth)acryloyl groups) as the functional groups of the polymeric liquid crystal compound that forms the phase retardation film, there is a tendency for improved adhesion between the cured layer of the polymeric liquid crystal compound and the alignment film.

[0129] As the substrate for coating the composition for forming a photo-aligned film, the same substrate that can be used in coating the composition for forming a phase retardation film described above can be used.

[0130] Photoreactive groups are groups that generate liquid crystal alignment ability through light irradiation. Specifically, examples include photoreactive groups that participate in orientation-inducing or isomerization reactions, dimerization reactions, photocrosslinking reactions, or photodecomposition reactions of molecules generated by light irradiation, thus becoming the origin of liquid crystal alignment ability. Among these, groups that participate in dimerization reactions or photocrosslinking reactions are preferred from the perspective of excellent alignment. As photoreactive groups, groups having unsaturated bonds, especially double bonds, are preferred, and groups having at least one selected from carbon-carbon double bonds (C=C bond), carbon-nitrogen double bonds (C=N bond), nitrogen-nitrogen double bonds (N=N bond), and carbon-oxygen double bonds (C=O bond) are particularly preferred.

[0131] Specifically, as such an alignment film, for example, the optical alignment film described in Japanese Patent Application Publication No. 2020-56834 and Japanese Patent Application Publication No. 2021-196514 can be used.

[0132] The thickness of the alignment film is preferably 10–3000 nm, more preferably 10–1000 nm, further preferably 10–500 nm, even more preferably 10–300 nm, and particularly preferably 30–300 nm. If the thickness of the alignment film is within the above range, it can exhibit good adhesion at the interface with the cured layer formed by the phase retardation film forming composition formed on the alignment film, and exert orientation confinement force, enabling the formation of a phase retardation film with a high orientation order.

[0133] There are no particular limitations on the method of coating the phase difference film forming composition and the photo-alignment film forming composition onto the substrate or alignment film. Known methods such as spin coating, extrusion coating, gravure coating, die coating, bar coating, applicator coating, and flexographic printing can be used.

[0134] When the composition for forming a phase retardation film contains a solvent, and in the case of a composition for forming a photo-alignment film that typically contains a solvent, the solvent is usually removed from the coated composition. Methods for solvent removal include natural drying, ventilation drying, heating drying, and reduced pressure drying. The coating is preferably dried such that the residual solvent in the coating is less than 1% by weight relative to the total mass of the coating. The amount of residual solvent can be quantified by peeling the coating off a substrate or the like and weighing it, immersing the coating in a solvent such as tetrahydrofuran that dissolves the coating, irradiating it with ultrasound for about 10 minutes to extract the dissolved components, and then analyzing the solution using gas chromatography. Drying conditions such as drying temperature and drying time can be appropriately determined based on the composition of the composition for forming a phase retardation film or the composition for forming an alignment film, the substrate, the material of the alignment film, etc.

[0135] In the coating of a composition for forming a phase retardation film, the polymeric liquid crystal compound is typically heated to a temperature above which it transitions to a liquid crystal state or a solution state, and then cooled to a temperature for liquid crystal orientation, thereby forming a liquid crystal phase.

[0136] The orientation temperature of the polymeric liquid crystal compound in the coating of the composition for forming the phase retardation film can be determined in advance by means of textural observation of the composition containing the polymeric liquid crystal compound. Alternatively, solvent removal and liquid crystal orientation can be performed simultaneously. While the temperature at this time depends on the solvent removed and the type of polymeric liquid crystal compound used, it is preferably in the range of 50–200°C, and more preferably in the range of 80–130°C.

[0137] While maintaining the polymerizable liquid crystal compound in its liquid crystal state, the polymerizable liquid crystal compound is polymerized and cured, thereby forming a phase retardation film as a cured layer of the liquid crystal composition. Photopolymerization is preferred as the polymerization method. In photopolymerization, the light used to irradiate the dried film is appropriately selected based on the type of polymerizable liquid crystal compound contained in the dried film (especially the type of polymerizable groups possessed by the polymerizable liquid crystal compound), the type of polymerization initiator, and their amounts.

[0138] (Thermoplastic resin layer and, in the case of a phase retardation film and / or bonding layer, other than the layer)

[0139] In addition to the thermoplastic resin layer, the phase retardation film and / or the bonding layer, the first phase retardation plate may also contain other layers besides these.

[0140] As other such layers, coating layers (surface treatment layers) can be exemplified both when the thermoplastic resin layer contained in the first retardation plate has a phase difference and when it does not. Specific examples of coating layers include hard coating layers, anti-glare layers, anti-reflective layers, antistatic layers, and antifouling layers. A single coating layer can have two or more functions (e.g., hard coating function and antifouling function). The thickness of the coating layer is not particularly limited, typically 0.5 to 100 μm, preferably 1 to 10 μm. The coating layer can be included in any part of the first retardation plate, preferably disposed adjacent to the thermoplastic resin layer when the thermoplastic resin layer has a phase difference, and adjacent to the thermoplastic resin layer or the retardation film contained in the first retardation plate when the thermoplastic resin layer does not have a phase difference.

[0141] There is no particular limitation on the method for forming the coating layer; known methods can be used. The coating layer can be formed by coating an adjacent layer (e.g., a thermoplastic resin layer or a retardation film), or it can be bonded together after the coating layer has been formed separately. Such bonding can be, for example, via a bonding layer formed by an adhesive. This bonding layer can be the same as the bonding layer described above used to bond the retardation film to a thermoplastic resin layer having a specified glass transition temperature and tensile modulus.

[0142] • Hard coating layer (hereinafter sometimes referred to as "HC layer")

[0143] The HC layer can be formed by curing an HC layer forming composition containing a reactive material that forms a cross-linked structure by irradiation with active energy rays or heat, but preferably a cured layer (cured resin layer) of the HC layer forming composition cured by irradiation with active energy rays.

[0144] In one embodiment of the invention, preferably, a cured resin layer is further included on the side of the first phase difference plate opposite to the polarizer side.

[0145] Reactive energy rays are defined as energy rays capable of decomposing compounds that produce active species to generate active species. Examples of reactive energy rays include visible light, ultraviolet light, infrared light, X-rays, alpha rays, beta rays, gamma rays, and electron beams. Among these, ultraviolet light is particularly preferred.

[0146] The HC layer forming composition contains at least one of a free radical polymerizable compound and a cationic polymerizable compound.

[0147] A free radical polymerizable compound is a compound having free radical polymerizable groups. The free radical polymerizable groups in a free radical polymerizable compound can be any functional group capable of undergoing a free radical polymerization reaction; examples include groups containing carbon-carbon unsaturated double bonds. Specifically, examples include vinyl and (meth)acryloyl groups. When the above-mentioned free radical polymerizable compound has two or more free radical polymerizable groups, these free radical polymerizable groups can be the same or different. From the viewpoint of improving the hardness of the HC layer, it is preferable that the free radical polymerizable compound has two or more free radical polymerizable groups per molecule.

[0148] From the viewpoint of high reactivity, compounds having (meth)acrylyl groups are preferred as free radical polymerizable compounds. For example, compounds called polyfunctional acrylate monomers having 2 to 6 (meth)acrylyl groups per molecule, oligomers having several (meth)acrylyl groups within their molecules and having a molecular weight of several hundred to several thousand, such as epoxy (meth)acrylates, urethane (meth)acrylates, and polyester (meth)acrylates, are preferred. Preferably, the HC layer forming composition contains one or more selected from epoxy (meth)acrylates, urethane (meth)acrylates, and polyester (meth)acrylates.

[0149] Cationic polymerizable compounds refer to compounds having cationic polymerizable groups such as epoxy groups, oxetyl groups, and vinyl ether groups. From the viewpoint of improving the hardness of the HC layer, the number of cationic polymerizable groups in one molecule of the cationic polymerizable compound is preferably 2 or more, more preferably 3 or more. In addition, as a cationic polymerizable compound, it is preferable to have at least one of epoxy groups and oxetyl groups as cationic polymerizable groups.

[0150] From the perspective of minimizing shrinkage associated with polymerization reactions, cyclic ether groups such as epoxy groups and oxetyl groups are preferred. Furthermore, compounds containing epoxy groups within cyclic ether groups offer the following advantages: they readily yield compounds with diverse structures, do not adversely affect the durability of the resulting HC layer, and allow for easy control of compatibility with free radical polymerizable compounds.

[0151] In addition, the oxobutyl group in the cyclic ether group has the following advantages compared with the epoxy group: the degree of polymerization is easy to increase, the toxicity is low, the network formation rate obtained from the cationic polymerizable compound of the obtained HC layer is accelerated, and even in the region where it is mixed with free radical polymerizable compound, unreacted monomers will not remain in the HC layer but will form an independent network.

[0152] Examples of cationic polymerizable compounds with epoxy groups include polyglycidyl ethers of polyols having alicyclic rings and alicyclic epoxy resins obtained by epoxidizing compounds containing cyclohexene or cyclopentene rings with a suitable oxidant such as hydrogen peroxide or peracid; alicyclic epoxy resins such as polyglycidyl ethers of aliphatic polyols or their alkylene oxide adducts, polyglycidyl esters of aliphatic long-chain polyacids, and homopolymers or copolymers of (meth)acrylate glycidyl esters; glycidyl ethers manufactured by reacting bisphenols such as bisphenol A, bisphenol F, or hydrogenated bisphenol A, or their alkylene oxide adducts or caprolactone adducts, with epichlorohydrin; phenolic epoxy resins; and glycidyl ether-type epoxy resins derived from bisphenols.

[0153] The HC layer forming composition may further comprise a polymerization initiator. Examples of polymerization initiators include free radical polymerization initiators, cationic polymerization initiators, and a combination of free radical and cationic polymerization initiators, which may be suitably selected for use. These polymerization initiators are decomposed by at least one of active energy irradiation and heating, generating free radicals or cations to drive free radical polymerization and cationic polymerization.

[0154] A free radical polymerization initiator is any reagent that can release a substance that initiates free radical polymerization by at least one of active energy irradiation and heating.

[0155] Examples of active energy ray free radical polymerization initiators include Type 1 free radical polymerization initiators that generate free radicals through molecular decomposition and Type 2 free radical polymerization initiators that coexist with tertiary amines and generate free radicals through hydrogen abstraction reactions. They can be used alone or in combination.

[0156] Examples of thermal free radical polymerization initiators include organic peroxides such as hydrogen peroxide and perbenzoic acid, as well as azo compounds such as azodibutyl nitrile, which can be used individually or in combination.

[0157] A cationic polymerization initiator is any reagent capable of releasing a substance that initiates cationic polymerization through at least one of irradiation with active energy rays or heating. Examples of cationic polymerization initiators include aromatic iodonium salts, aromatic sulfonium salts, and cyclopentadienyl iron(II) complexes. Depending on their structure, they can initiate cationic polymerization through any one or any of irradiation with active energy rays or heating.

[0158] When the HC layer forming composition contains a polymerization initiator, its content is preferably 0.1 to 10% by mass relative to the total mass of the HC layer forming composition. If the content of the polymerization initiator is above the lower limit mentioned above, the curing of the HC layer forming composition can be sufficiently promoted, and the resulting HC layer can have the desired mechanical properties or adhesion. If the content of the polymerization initiator is below the upper limit mentioned above, poor adhesion, cracking, or curling caused by curing shrinkage can be suppressed.

[0159] The HC layer forming composition may further comprise one or more additives selected from solvents and (other than polymerization initiators). The solvent is known in the art as long as it can dissolve or disperse the polymerizable compound and (if included) the polymerization initiator. Examples of additives include inorganic particles, leveling agents, stabilizers, surfactants, antistatic agents, lubricants, and antifouling agents, and one or more of these may be incorporated into the HC layer forming composition.

[0160] By including a hard coating on the first phase retardation plate, the mechanical strength of the first phase retardation plate can be improved, thereby improving the mechanical strength of the circular polarization plate.

[0161] It should be noted that in the first retardation plate of the present invention, the layers required to ensure, maintain, and / or enhance the function of the retardation film or retardation layer, as well as the layers integrally formed with the retardation layer, specifically, such as the thermoplastic resin layer, the retardation layer, other layers such as the hard coating layer adjacent to or close to the retardation layer, and the bonding layer for bonding these layers, are considered as components constituting the first retardation plate. On the other hand, in the present invention, generally, the bonding layer for bonding the first retardation plate to other layers such as the polarizer is not considered as a component of the first retardation plate or the polarizer.

[0162] <Polarizing plate>

[0163] The circular polarizer of the present invention includes a cured layer of a polymeric liquid crystal composition comprising a polymeric liquid crystal compound and a dichroic pigment. This cured layer corresponds to a polarizing film. The polarizing film can be a single layer or multiple layers comprising two or more of the cured polymeric liquid crystal composition, or it can be multiple layers comprising one or more layers of the cured polymeric liquid crystal composition and one or more alignment films for forming these layers. Preferably, the polarizing film is a horizontally polarizing film (hereinafter also simply referred to as a "horizontally polarizing film" or "linearly polarizing film") cured with the polymeric liquid crystal compound and dichroic pigment aligned horizontally relative to the plane of the polarizing film. Horizontally polarizing films typically function to allow light vibrating in the transmission axis direction to pass through, but block polarized light with vibration components perpendicular to it, thus functioning as a polarizing film that extracts linearly polarized light from incident natural light.

[0164] From the viewpoint of polarization function and thinness, the thickness of the polarizing film is preferably 0.1 to 5 μm, more preferably 0.5 to 4 μm, even more preferably 1 to 3.5 μm, and particularly preferably 1.5 to 3.3 μm. The thickness of the polarizing film is the thickness of the layer containing the cured polymeric liquid crystal composition contained in the polarizing film. In the case where the polarizing film has an alignment film, the thickness of the alignment film is not included in the thickness of the polarizing film.

[0165] A polarization film forming composition for forming a polarization film will be described. The polymerizable liquid crystal compound contained in the polarization film forming composition is a compound having at least one polymerizable group and exhibiting liquid crystal properties. Here, a polymerizable group refers to a group that participates in a polymerization reaction, preferably a photopolymerizable group. Examples of photopolymerizable groups include groups that are the same as those that can be present in the polymerizable liquid crystal compound forming the phase retardation film.

[0166] The polymerizable liquid crystal compound is preferably a liquid crystal compound exhibiting a smectic liquid crystal phase. By using a polymerizable liquid crystal compound exhibiting a smectic liquid crystal phase, a polarizing film with high orientation order and excellent polarization function can be formed. From the viewpoint of achieving higher orientation order, the liquid crystal state exhibited by the polymerizable liquid crystal compound is more preferably a higher-order smectic phase (higher-order smectic liquid crystal state). Here, higher-order smectic phase refers to smectic B phase, smectic D phase, smectic E phase, smectic F phase, smectic G phase, smectic H phase, smectic I phase, smectic J phase, smectic K phase, and smectic L phase, among which smectic B phase, smectic F phase, and smectic I phase are more preferred, and smectic B phase is even more preferred. The liquid crystal property can be thermotropic liquid crystal or lyotropic liquid crystal, and from the viewpoint of being able to achieve dense film thickness control, thermotropic liquid crystal is preferred. In addition, the polymerizable liquid crystal compound can be a monomer, an oligomer formed by polymerization of polymeric groups, or a polymer.

[0167] Examples of such polymeric liquid crystal compounds include compounds represented by formula (A) (hereinafter also referred to as "polymeric liquid crystal compound (A)").

[0168] U 1 -V 1 -W 1 -(X) 1 -Y 1 ) n -X 2 -W 2 -V 2 -U 2 (A)

[0169] In formula (A),

[0170] X 1and X 2 Each of these groups independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom in the divalent aromatic group or divalent alicyclic hydrocarbon group can be substituted by a substituent selected from halogen atoms, alkyl groups with 1 to 4 carbon atoms, fluoroalkyl groups with 1 to 4 carbon atoms, alkoxy groups with 1 to 4 carbon atoms, cyano groups, and nitro groups. The carbon atoms constituting the divalent aromatic group or divalent alicyclic hydrocarbon group can be substituted by oxygen atoms, sulfur atoms, or nitrogen atoms. Wherein, X 1 and X 2 At least one of them is 1,4-phenylene, which may have the above-mentioned substituents, or cyclohexane-1,4-diyl, which may have the above-mentioned substituents.

[0171] Y 1 It is a single bond or a divalent linker.

[0172] When n is 1 to 3, and n is 2 or more, there are multiple X's. 1 They can be the same or different. X 2 Can be used with multiple X 1 Any one or all of them can be the same, or they can be different. Furthermore, when n is 2 or more, multiple Ys... 1 They can be the same or different. From the viewpoint of liquid crystal properties, n is preferably 2 or more.

[0173] U 1 It represents a hydrogen atom or a polymeric group.

[0174] U 2 It indicates a polymerizable group.

[0175] W 1 and W 2 Each is an independent single bond or a divalent linker.

[0176] V 1 and V 2 Each can independently represent an alkyldiyl group with 1 to 20 carbon atoms that can have substituents, wherein the -CH2- group constituting the alkyldiyl group can be replaced by -O-, -CO-, -S- or -NH-.

[0177] In polymeric liquid crystal compound (A), X 1 and X 2 Each is preferably 1,4-phenylene, which may have substituents, or cyclohexane-1,4-diyl, which may have substituents, X 1 and X 2At least one of them is a 1,4-phenylene that may have a substituent, or a cyclohexane-1,4-diyl that may have a substituent, preferably trans-cyclohexane-1,4-diyl. Examples of substituents that may be present in the 1,4-phenylene or the cyclohexane-1,4-diyl that may have a substituent include alkyl groups having 1 to 4 carbon atoms such as methyl, ethyl, and butyl, cyano groups, and halogen atoms such as chlorine and fluorine atoms. Unsubstituted is preferred.

[0178] Furthermore, from the viewpoint of the manifestation of smectic liquid crystal properties, the polymeric liquid crystal compound (A) preferably has an asymmetric structure in the part represented by formula (A1) in formula (A) (hereinafter referred to as "partial structure (A1)").

[0179] -(X) 1 -Y 1 ) n -X 2 - (A1)

[0180] [In the formula, X] 1 Y 1 X 2 [and n] have the same meaning as above.

[0181] As a polymeric liquid crystal compound (A) with a partially asymmetric structure (A1), examples include n=1 and 1 X. 1 With X 2 These are polymeric liquid crystal compounds (A) with different structures from each other. Additionally, examples can be given where n is 2 and there are 2 Y atoms. 1 They have the same structure and two X's 1 For the same structure and 1 X 2 To be with these two X 1 Polymerizable liquid crystal compounds with different structures (A); 2 X 1 In and W 1 bonded X 1 For another X 1 and X 2 Different structures, and another X 1 With X 2 A is a polymeric liquid crystal compound with the same structure as each other. Furthermore, examples can be given where n is 3 and there are 3 Y atoms. 1 They have the same structure and 3 X's 1 And 1 X 2 A polymeric liquid crystal compound (A) with a structure that is completely different from the other three.

[0182] Y 1Preferred bonds include -CH2CH2-, -CH2O-, -CH2CH2O-, -COO-, -OCOO-, single bonds, -N=N-, and -CR. a =CR b -、-C≡C-、-CR a =N- or -CO-NR a -. R a and R b Each can independently represent an alkyl group having 1 to 4 hydrogen atoms or carbon atoms. Y 1 More preferably, it is -CH2CH2-, -COO-, or a single bond, in the presence of multiple Y 1 In the case of X 2 Bonded Y 1 More preferably, it is -CH2CH2- or -CH2O-. In X 1 and X 2 When all of them have the same structure, it is preferable to have two or more Y atoms with different bonding methods. 1 In the existence of multiple Ys as different bonding methods 1 In such cases, it becomes an asymmetric structure, and therefore tends to exhibit smectic liquid crystal properties.

[0183] U 2 It is a polymerizable group. U 1 It is a hydrogen atom or a polymeric group, preferably a polymeric group. U is preferred. 1 and U 2 All of these are polymerizable groups, preferably free radical polymerizable groups. Examples of polymerizable groups include vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, (meth)acryloyl, (meth)acryloyloxy, ethylene oxide, and oxetyl. Free radical polymerizable groups are preferred, (meth)acryloyl, vinyl, and vinyloxy are more preferred, and (meth)acryloyl and (meth)acryloyloxy are even more preferred. 1 The polymeric groups shown are related to U 2 The polymerizable groups shown may be different from each other, but are preferably of the same kind. In addition, the polymerizable groups may be in a polymerized state or an unpolymerized state, but are preferably in an unpolymerized state.

[0184] As V 1 and V 2 Examples of alkyldiyl groups shown include methylene, ethylene, propane-1,3-diyl, butane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, decane-1,10-diyl, undecane-1,11-diyl, tetradecane-1,14-diyl, and eicosane-1,20-diyl.1 and V 2 Preferably, it is an alkyldiyl group with 2 to 12 carbon atoms, and more preferably an alkyldiyl group with 6 to 12 carbon atoms.

[0185] Examples of substituents that may be present in the alkyl diester include cyano groups and halogen atoms. The alkyl diester is preferably unsubstituted, and more preferably an unsubstituted straight-chain alkyl diester.

[0186] W 1 and W 2 The components are preferably single bonds, -O-, -S-, -COO-, or -OCOO-, and more preferably single bonds or -O-.

[0187] As a structure that readily exhibits smectic liquid crystal properties, a molecular structure with asymmetry in its molecular structure is preferred. Specifically, polymeric liquid crystal compounds having structures shown in formulas (Aa) to (Ai) readily exhibit smectic liquid crystal properties and are suitable as polymeric liquid crystal compounds (A). Furthermore, from the viewpoint of readily exhibiting higher-order smectic liquid crystal properties, structures having formulas (Aa), (Ab), or (Ac) are more preferred. It should be noted that in formulas (Aa) to (Ai), Indicates a connection key (single key).

[0188] [Chemical Formula 1]

[0189]

[0190] As a polymerizable liquid crystal compound (A), specifically, compounds represented by formulas (A-1) to (A-25) can be cited as examples. When the polymerizable liquid crystal compound (A) has a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably the trans form.

[0191] [Chemical Formula 2]

[0192]

[0193] [Chemical Formula 3]

[0194]

[0195] [Chemical Formula 4]

[0196]

[0197] Preferably, at least one compound is selected from the compounds shown in formulas (A-2), (A-3), (A-4), (A-5), (A-6), (A-7), (A-8), (A-13), (A-14), (A-15), (A-16), and (A-17). As the polymerizable liquid crystal compound (A), one compound may be used alone, or two or more compounds may be used in combination.

[0198] The polymerizable liquid crystal compound (A) can be manufactured by known methods as described in Lub et al., Recl.Trav.Chim.Pays-Bas, 115, 321-328 (1996), or Japanese Patent No. 4719156.

[0199] Provided that the effects of the present invention are not compromised, the composition for forming a polarizing film may contain polymeric liquid crystal compounds other than polymeric liquid crystal compound (A). From the viewpoint of obtaining a polarizing film with high orientation order, the proportion of polymeric liquid crystal compound (A) relative to the total mass of all polymeric liquid crystal compounds in the composition for forming a polarizing film is preferably 51% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more. It may also be entirely (100% by mass) polymeric liquid crystal compound (A).

[0200] When the polarization film forming composition contains two or more polymeric liquid crystal compounds, it is preferable that at least one of them is a polymeric liquid crystal compound (A), or all of the components in the polarization film forming composition may be polymeric liquid crystal compounds (A).

[0201] The content of the polymeric liquid crystal compound in the polarization film forming composition is preferably 40 to 99.9% by mass, more preferably 60 to 99.9% by mass, and even more preferably 70 to 99% by mass, relative to the solid component of the polarization film forming composition. If the content of the polymeric liquid crystal compound is within the above range, there is a tendency for the orientation of the polymeric liquid crystal compound to become higher.

[0202] The composition for forming polarizing films also includes a dichroic pigment. Here, a dichroic pigment refers to a pigment that has the property that its absorbance along the long axis of the molecule differs from its absorbance along the short axis. There are no particular limitations on the dichroic pigment as long as it possesses the aforementioned property; it can be either a dye or a pigment. Two or more dyes or pigments can be used separately, or a combination of dyes and pigments can be used. Dichroic pigments can be used alone or in combination. To achieve absorption across the entire visible light spectrum, it is preferable to combine two or more dichroic pigments, and more preferably three or more dichroic pigments. In particular, by mixing two or more dichroic pigments with different absorption wavelengths, polarizing films of various hues can be produced, and polarizing films with absorption across the entire visible light spectrum can be manufactured.

[0203] As a dichroic pigment, it is preferable to have the property of absorbing visible light, and preferably to have a maximum absorption wavelength (λ) in the range of 300–700 nm. MAX Examples of such dichroic pigments include acridine pigments, oxazine pigments, anthocyanins, naphthalene pigments, azo pigments, and anthraquinone pigments. Among these, azo pigments are preferred.

[0204] Examples of azo dyes include monoazo dyes, diazo dyes, triazo dyes, tetraazo dyes, and succinylazo dyes, with diazo dyes and triazo dyes being preferred. Examples of compounds represented by formula (I) (hereinafter also referred to as "compound (I)").

[0205] K 1 (-N=NK) 2 ) p -N=NK 3 (I)

[0206] In equation (I), K 1 and K 3 Independently representing phenyl groups that may have substituents, naphthyl groups that may have substituents, benzoic acid ester groups that may have substituents, or monovalent heterocyclic groups that may have substituents. K 2 This indicates a p-phenylene group that may have substituents, a naphth-1,4-diyl group that may have substituents, a 4,4'-pyridyl group that may have substituents, or a divalent heterocyclic group that may have substituents. p represents an integer from 0 to 4. When p is an integer greater than 2, multiple K groups are represented. 2 They can be the same or different. Within the visible absorption range, -N=N- bonds can be replaced by -C=C-, -COO-, -NHCO-, or -N=CH- bonds.

[0207] Examples of monovalent heterocyclic groups include those obtained by removing one hydrogen atom from heterocyclic compounds such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, and benzoxazole. Examples of divalent heterocyclic groups include those obtained by removing two hydrogen atoms from the aforementioned heterocyclic compounds.

[0208] As K 1 and K 3 The phenyl, naphthyl, benzoic acid phenyl ester group and monovalent heterocyclic group, as well as K 2 The substituents that can be arbitrarily present in p-phenylene, naphth-1,4-diyl, 4,4'-indene, and divalent heterocyclic groups include alkyl groups with 1 to 20 carbon atoms, alkyl groups with 1 to 20 carbon atoms having polymerizable groups, alkenyl groups with 1 to 4 carbon atoms; alkoxy groups with 1 to 20 carbon atoms such as methoxy, ethoxy, and butoxy; alkoxy groups with 1 to 20 carbon atoms having polymerizable groups; fluoroalkyl groups with 1 to 4 carbon atoms such as trifluoromethyl; cyano; nitro; halogen atoms; substituted or unsubstituted amino groups such as amino, diethylamino, and pyrrolidinyl (substituted amino groups refer to amino groups having 1 or 2 alkyl groups with 1 to 6 carbon atoms, amino groups having 1 or 2 alkyl groups with 1 to 6 carbon atoms, or amino groups having 2 to 8 alkyl groups bonded together to form an alkyldiyl group. Unsubstituted amino groups are -NH2.) etc. It should be noted that, as examples of the aforementioned polymerizable groups, (meth)acryloyl group, (meth)acryloyloxy group, etc.

[0209] In compound (I), the preferred compound is one of the following formulas (I-1) to (I-8).

[0210] [Chemical Formula 5]

[0211]

[0212] [In formulas (I-1) to (I-8),

[0213] B 1 ~B 30 Each can independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of substituted and unsubstituted amino groups are as described above), a chlorine atom, or a trifluoromethyl group.

[0214] n1 to n4 represent integers from 0 to 3 independently.

[0215] When n1 is 2 or more, multiple B 2 They can be the same or different.

[0216] When n² is greater than 2, multiple B6 They can be the same or different.

[0217] When n3 is 2 or more, multiple B 9 They can be the same or different.

[0218] When n4 is 2 or more, multiple B 14 They can be the same or different.

[0219] The preferred anthraquinone pigment is the compound shown in formula (I-9).

[0220] [Chemical Formula 6]

[0221]

[0222] In equation (I-9),

[0223] R 1 ~R 8 Each independently represents a hydrogen atom, -R x -NH2, -NHR x -NR x 2. -SR x Or halogen atoms.

[0224] R x This refers to an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0225] The preferred compound is the one shown in formula (I-10) as the aforementioned oxazine (Japanese: オキサジン) pigment.

[0226] [Chemical Formula 7]

[0227]

[0228] In formula (I-10),

[0229] R 9 ~R 15 Each independently represents a hydrogen atom, -R x -NH2, -NHR x -NR x 2. -SR x Or halogen atoms.

[0230] R x This refers to an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0231] The preferred acridine dye is the compound shown in formula (I-11).

[0232] [Chemical Formula 8]

[0233]

[0234] In formula (I-11),

[0235] R 16 ~R 23 Each independently represents a hydrogen atom, -R x -NH2, -NHR x -NR x 2. -SR x Or halogen atoms.

[0236] R x This refers to an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms.

[0237] In equations (I-9), (I-10), and (I-11), R is used as... x Alkyl groups having 1 to 6 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, and hexyl, while aryl groups having 6 to 12 carbon atoms include phenyl, tolyl, xylyl, and naphthyl.

[0238] As the aforementioned anthocyanins, the compounds shown in formula (I-12) and formula (I-13) are preferred.

[0239] [Chemical Formula 9]

[0240]

[0241] In equation (I-12),

[0242] D 1 and D 2 The groups represented by any one of formulas (I-12a) to (I-12d) are independently represented.

[0243] [Chemical Formula 10]

[0244]

[0245] n5 represents an integer from 1 to 3.

[0246] [Chemical Formula 11]

[0247]

[0248] In formula (I-13),

[0249] D 3 and D 4 The groups represented by any one of the formulas (I-13a) to (I-13h) are independently represented.

[0250] [Chemical Formula 12]

[0251]

[0252] n6 represents an integer from 1 to 3.

[0253] The weight-average molecular weight of dichroic pigments is typically 300–2000, preferably 400–1000.

[0254] The content of the dichroic pigment in the polarizing film forming composition can be appropriately determined according to the type of dichroic pigment used, etc., and is preferably 1 to 60% by mass, more preferably 1 to 20% by mass, and even more preferably 1 to 15% by mass, relative to the solid content of the polarizing film forming composition. If the content of the dichroic pigment is within the above range, the orientation of the polymerizable liquid crystal compound is not easily disturbed, and a polarizing film with high orientation order can be obtained.

[0255] The composition for forming a polarization film may include a polymerization initiator. The polymerization initiator is a compound capable of initiating a polymerization reaction of polymerizable liquid crystal compounds, etc. Examples of polymerization initiators include those previously exemplified as polymerization initiators that can be used when forming a phase retardation film.

[0256] The content of the polymerization initiator is preferably 0.1 to 20 parts by mass relative to 100 parts by mass of the polymerizable liquid crystal compound, more preferably 0.1 to 15 parts by mass, even more preferably 0.5 to 10 parts by mass, and particularly preferably 0.5 to 8 parts by mass. If the content of the polymerization initiator is within the above range, the polymerization reaction can be carried out without significantly disturbing the orientation of the polymerizable liquid crystal compound.

[0257] The composition for forming a polarizing film may contain a leveling agent. Examples of leveling agents include those previously exemplified that are also used when forming a phase retardation film.

[0258] When the composition for forming the polarizing film contains a leveling agent, its content is preferably 0.01 to 5 parts by mass relative to 100 parts by mass of the polymeric liquid crystal compound, more preferably 0.05 to 3 parts by mass. If the content of the leveling agent is within the above range, there is a tendency to easily orient the polymeric liquid crystal compound, reduce the likelihood of unevenness, and obtain a smoother polarizing film.

[0259] The composition for forming a polarizing film may contain additives other than leveling agents. Examples of such additives include polymerizable non-liquid crystal compounds, photosensitizers, antioxidants, release agents, stabilizers, colorants such as bluing agents, flame retardants, and lubricants. When other additives are included, their content is preferably more than 0% and less than 20% by mass, and more preferably more than 0% and less than 10% by mass, relative to the solid content of the composition for forming a polarizing film.

[0260] The polarizing film forming composition can be manufactured using conventional liquid crystal composition preparation methods. It is typically prepared by mixing and stirring a polymerizable liquid crystal compound, a dichroic pigment, a desired polymerization initiator, and the aforementioned additives. Furthermore, liquid crystal compounds that generally exhibit smectic liquid crystal properties have high viscosity; therefore, from the viewpoint of improving the coatability of the liquid crystal composition to facilitate the formation of a polarizing film, the viscosity can be adjusted by adding a solvent to the composition.

[0261] The solvent can be appropriately selected based on the solubility of the polymerizable liquid crystal compound and dichroic pigment used, and is preferably a solvent that can completely dissolve the above components and is inactive to the polymerization reaction. As a specific solvent, the same solvents previously exemplified as those that can be used to form the phase retardation film can be cited.

[0262] The solvent content is preferably 100 to 1900 parts by mass relative to 100 parts by mass of the solid component of the composition for forming the polarizing film, more preferably 150 to 1000 parts by mass, and even more preferably 180 to 800 parts by mass.

[0263] In this invention, the cured layer formed by the polarizing film forming composition is preferably a liquid crystal cured film with a high degree of orientation order. A liquid crystal cured film with a high degree of orientation order can produce Bragg peaks from higher-order structures such as hexagonal phases and crystalline phases in X-ray diffraction measurements. A Bragg peak refers to a peak arising from a planar periodic structure of molecular orientation. Therefore, the polarizing film (cured layer) constituting the polarizing plate of this invention preferably displays a Bragg peak in X-ray diffraction measurements. That is, in this invention, the polarizing film (cured layer) is preferably oriented in a manner that allows the film to display a Bragg peak in X-ray diffraction measurements. In one embodiment of this invention, the planar periodic interval of molecular orientation is preferably 3.0 to 6.0 Å. A high degree of orientation order, such as displaying a Bragg peak, can be achieved by controlling the type of polymeric liquid crystal compound used, the type and amount of dichroic pigment, and the type and amount of polymerization initiator, etc.

[0264] In this invention, the polarizing film may include an alignment film. Examples of alignment films include those previously exemplified, which are also used when forming a phase retardation film.

[0265] Polarizing films can be manufactured, for example, by a method including the following steps:

[0266] The step of forming a coating film of the composition for forming a polarizing film;

[0267] The step of removing the solvent from the above coating film;

[0268] The steps include heating the liquid crystal compound to a temperature above which the polymeric liquid crystal compound phase transforms into a liquid phase, and then cooling it to transform the polymeric liquid crystal compound phase into a liquid crystal phase (e.g., a smectic liquid crystal phase); and...

[0269] The step of polymerizing a polymerizable liquid crystal compound while maintaining the above-described liquid crystal phase.

[0270] The formation of a coating film of the polarizing film forming composition can be achieved, for example, by coating the polarizing film forming composition onto a substrate, an alignment film, or the like. The substrate can be a layer constituting the polarizing plate of the present invention, but in one embodiment of the present invention, a substrate that is ultimately peeled off is preferred. Examples of substrates include those previously exemplified as substrates that can be used when forming a retardation film.

[0271] The coating method for the composition used to form the polarization film and the curing conditions using active energy rays are examples of methods that can be used in the fabrication of the phase retardation film.

[0272] In addition to the polarizing film, a polarizing plate may also contain other layers.

[0273] Other such layers include, for example, hard coatings, top coatings, anti-reflective layers, anti-fouling layers, vapor barrier layers, tone adjustment layers, and refractive index adjustment layers. One of these other layers may have two or more functions (e.g., hard coating function and anti-fouling function).

[0274] As a hard coating, the same hard coating that can be included in the first phase retardation plate can be used.

[0275] The outer coating can be formed from a composition (composition for forming the outer coating) that possesses excellent solvent properties, transparency, mechanical strength, thermal stability, opacity, and isotropy. Examples of materials constituting the outer coating include photocurable resins or water-soluble polymers; for instance, (meth)acrylic resins, polyvinyl alcohol resins, and polyamide epoxy resins can be used. The thickness of the outer coating can be, for example, from 0.1 μm to 10 μm.

[0276] The method for forming other layers such as hard coatings or outer coatings is not particularly limited, and known methods can be used. Hard coatings or outer coatings can be formed by applying a hard coating forming composition or an outer coating forming composition onto the polarizing film, or by forming a hard coating or outer coating on a substrate and then forming the polarizing film thereon, or by forming the polarizing film and other layers separately and then bonding them together. Such bonding can be, for example, via a bonding layer formed by an adhesive. This bonding layer can be the same as the bonding layer described above used to bond the retardation film to a thermoplastic resin layer having a specified glass transition temperature and tensile modulus. The aforementioned substrate can be a layer constituting the polarizing plate of the present invention, but in one embodiment of the present invention, it is preferable to eventually peel it off. Examples of substrates include those previously exemplified as substrates that can be used when forming the retardation film.

[0277] When stacking the polarizer onto the first retardation plate, it is preferable to stack them such that the absorption axis of the polarizer is substantially 45° to the slow axis (optical axis) of the first retardation plate. By stacking them such that the absorption axis of the polarizer is substantially 45° to the slow axis (optical axis) of the first retardation plate, the function of a circular polarizer can be obtained. It should be noted that substantially 45° is typically in the range of 45 ± 5°. The bonding of the polarizer to the first retardation plate can be performed, for example, via a bonding layer formed by an adhesive. This bonding layer can be the same as the bonding layer described above used to bond the retardation film to a thermoplastic resin layer having a specified glass transition temperature and tensile modulus.

[0278] In one embodiment of the present invention, an adhesive is preferably used as the bonding agent for bonding the polarizer to the first retardation plate. Using an adhesive as the bonding agent for bonding the polarizer to the first retardation plate can reduce the reflectivity in the display device. When assembling the circular polarizer of the present invention into the display device, the effect of reducing reflectivity can be further improved by positioning the first retardation plate closer to the observation side than the second retardation plate.

[0279] <Second phase difference plate>

[0280] In addition to the first phase retardation plate and the polarizing plate described above, the circular polarizing plate of the present invention also includes a second phase retardation plate. The second phase retardation plate comprises a cured layer of a polymeric liquid crystal composition, wherein the polymeric liquid crystal composition comprises a polymeric liquid crystal compound. In the second phase retardation plate, the cured layer corresponds to a phase retardation film. The phase retardation film is either a single layer (the cured layer) made of a polymer comprising a polymeric liquid crystal compound, or a layer composed of the cured layer and an alignment film. In the present invention, the bonding layer used to attach the second phase retardation plate to other layers such as the polarizing plate is not considered a constituent component of the second phase retardation plate or the polarizing plate.

[0281] In order for the second phase difference plate to function as a phase difference plate, the second phase difference plate preferably has a phase difference value that satisfies the following equations (10) to (12):

[0282] 90nm≤Re2(450)≤140nm (10)

[0283] 110nm≤Re2(550)≤170nm (11)

[0284] 120nm≤Re2(650)≤180nm (12)

[0285] [In equations (10) to (12), Re2(λ) represents the in-plane phase difference value of the second phase difference plate at wavelength λnm].

[0286] If the in-plane phase difference Re2(λ) of the second phase retardation plate is within the range of equations (10) to (12), then the second phase retardation plate becomes a phase retardation plate that functions as a 1 / 4 wavelength plate. When a circular polarizer containing the second phase retardation plate is applied to a display device, the visibility of the display device can be improved even if the display device is placed in a high-temperature environment, and even if the circular polarizer in the display device is shaped or perforated. A further preferred range of the above-mentioned in-plane phase difference value is 80nm≤Re2(450)≤130nm, 100nm≤Re2(550)≤160nm and 125nm≤Re2(650)≤170nm.

[0287] The cured layer contained in the second phase difference plate can exhibit either positive wavelength dispersion or reverse wavelength dispersion.

[0288] In one embodiment of the present invention, the cured layer contained in the second phase difference plate preferably exhibits reverse wavelength dispersion, and more preferably satisfies the following equations (13) and (14). It should be noted that Re2(λ) represents the in-plane phase difference value for light with wavelength λnm.

[0289] Re2(450) / Re2(550)<1(13)

[0290] 1<Re2(650) / Re2(550) (14)

[0291] By making the cured layer contained in the second phase retardation plate exhibit reverse wavelength dispersion, when a circular polarizer containing the second phase retardation plate is applied to a display device, especially when the first phase retardation plate is located on the observation side closer to the second phase retardation plate, the visibility of the display device can be further improved even when the display device is placed in a high-temperature environment, and even when the circular polarizer plate in the display device has been shaped or perforated.

[0292] From the viewpoint that improving the inverse wavelength dispersion can further enhance the visibility of the aforementioned display device, Re2(450) / Re2(550) is preferably 0.70 or more, more preferably 0.80 or more, even more preferably 0.83 or more, and preferably 0.99 or less. Furthermore, Re2(650) / Re2(550) is preferably 1.01 or more, and preferably 1.50 or less, more preferably 1.30 or less, and even more preferably 1.20 or less.

[0293] The aforementioned in-plane phase difference values ​​or their ratios can be adjusted using the same method as the in-plane phase difference values ​​or their ratios in the aforementioned first phase difference plate.

[0294] The retardation film is preferably a "horizontally oriented liquid crystal cured film" formed by curing a polymeric liquid crystal compound in a state of horizontal orientation relative to the plane of the retardation film. The retardation film preferably satisfies the above formulas (10) to (12).

[0295] The phase retardation film can also be a phase retardation film that functions as a positive C-plate (nx≈ny<nz), or a phase retardation film that functions as a half-wavelength plate.

[0296] In one embodiment of the present invention, the phase difference value Re1 (550) of the first phase difference plate at a wavelength of 550 nm and the phase difference value Re2 (550) of the second phase difference plate at a wavelength of 550 nm preferably satisfy the following equation (1):

[0297] Re1(550)<Re2(550) (1).

[0298] By satisfying the above formula (1), when the circular polarizing plate of the present invention is applied to a display device, even if the display device is placed in a high-temperature environment, and even if the circular polarizing plate is shaped or perforated in the display device, the visibility of the display device can be further improved.

[0299] As the polymeric liquid crystal compound used to form the retardation film contained in the second retardation plate, the same polymeric liquid crystal compound described with respect to the first retardation plate can be used. Alternatively, the polymeric liquid crystal compound described below can also be used. It should be noted that the components optionally included in the retardation film contained in the second retardation plate, the alignment film and other layers that the second retardation plate may include, the preparation of the composition for forming the aforementioned retardation film, and the formation of the aforementioned retardation film can all follow the same procedures as described with respect to the first retardation plate.

[0300] As an example of a polymeric liquid crystal compound (hereinafter also referred to as "polymeric liquid crystal compound (B)") that forms the phase difference film contained in the second phase difference plate, from the viewpoint of endowing the phase difference properties shown in the above formulas (13) and (14), all compounds that satisfy the following (I) to (IV) can be cited.

[0301] (I) Compounds with thermotropic liquid crystal properties.

[0302] (II) The polymeric liquid crystal compound has π electrons in the long axis direction (a).

[0303] (III) It has π electrons in the direction intersecting the major axis (a) [intersecting direction (b)].

[0304] (IV) D(πa) and D(πb) are in a relationship of 0 ≤ [D(πa) / D(πb)] ≤ 1.

[0305] [That is, the π electron density in the cross direction (b) is greater than the π electron density in the major axis direction (a)]

[0306] The D(πa) is the π electron density in the long axis (a) of the polymeric liquid crystal compound, defined by the following equation (i), when the total number of π electrons present in the long axis direction (a) is set as N(πa) and the total number of molecular weights present in the long axis direction is set as N(Aa):

[0307] D(πa)=N(πa) / N(Aa) (i)

[0308] The D(πb) is the π electron density in the cross direction (b) of the polymeric liquid crystal compound, defined by the following formula (ii), when the total number of π electrons present in the cross direction (b) is set as N(πb) and the total number of molecular weights present in the cross direction (b) is set as N(Ab):

[0309] D(πb)=N(πb) / N(Ab) (ii).

[0310] It should be noted that, for all polymeric liquid crystal compounds (B) that satisfy (I) to (IV) above, a nematic phase or a smectic phase can be formed, for example, by heating to a temperature above the phase transition temperature. The nematic or smectic phase formed by the orientation of this polymeric liquid crystal compound is typically oriented such that the long axis directions of the polymeric liquid crystal compounds are parallel to each other, and this long axis direction becomes the orientation direction of the nematic or smectic phase.

[0311] Polymerizable liquid crystal compounds (B) possessing the above-mentioned properties generally exhibit reverse wavelength dispersion. Specifically, compounds that satisfy the properties described in (I) to (IV) above can be exemplified, for example, by compounds represented by the following formula (B1).

[0312] [Chemical Formula 13]

[0313]

[0314] The compound shown in formula (B1) above can be used alone or in combination of two or more.

[0315] In formula (B1), Ar represents a divalent group having an aromatic group that may have substituents. Examples of such aromatic groups include those exemplified in (Ar-1) to (Ar-23) described later. Furthermore, Ar may have two or more aromatic groups. These aromatic groups may contain at least one of nitrogen, oxygen, or sulfur atoms. When Ar contains two or more aromatic groups, these two or more aromatic groups may be bonded to each other via single bonds, -CO-O-, -O-, or other divalent bonding groups.

[0316] In equation (B1), G 1 and G 2 Each of these groups independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group. Here, the hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group may be replaced by a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and the carbon atom constituting the divalent aromatic group or divalent alicyclic hydrocarbon group may be replaced by an oxygen atom, a sulfur atom, or a nitrogen atom.

[0317] In formula (B1), L 1 L 2 B 1 and B 2 Each is an independent single bond or a divalent linker.

[0318] In equation (B1), k and l independently represent integers from 0 to 3, satisfying the relationship 1 ≤ k + l. Here, in the case of 2 ≤ k + l, B 1 and B 2 G 1and G 2 They can be the same as each other, or they can be different.

[0319] In equation (B1), E 1 and E 2 Each alkyl group independently represents an alkyl group with 1 to 17 carbon atoms, more preferably an alkyl group with 4 to 12 carbon atoms. In addition, the hydrogen atoms contained in the alkyl group can be replaced by halogen atoms, and the -CH2- contained in the alkyl group can be replaced by -O-, -S-, or -C(=O)-.

[0320] In equation (B1), P 1 and P 2 Each of the following groups represents a polymeric group or a hydrogen atom independently, with at least one being a polymeric group.

[0321] G 1 and G 2 Each of the following is preferably 1,4-phenylene diel that can be substituted with at least one substituent selected from halogen atoms and alkyl groups having 1 to 4 carbon atoms, or 1,4-cyclohexane diel that can be substituted with at least one substituent selected from halogen atoms and alkyl groups having 1 to 4 carbon atoms; more preferably methyl-substituted 1,4-phenylene diel, unsubstituted 1,4-phenylene diel, or unsubstituted 1,4-trans-cyclohexane diel; and particularly preferably unsubstituted 1,4-phenylene diel or unsubstituted 1,4-trans-cyclohexane diel.

[0322] In addition, it is preferable that there are multiple Gs. 1 and G 2 At least one of them is a divalent alicyclic hydrocarbon group, and more preferably it is with L 1 or L 2 bonded G 1 and G 2 At least one of them is a divalent alicyclic hydrocarbon group.

[0323] L 1 and L 2 Each is preferably a single bond, an alkylene group having 1 to 4 carbon atoms, or an -O-, -S-, or -R group. a1 OR a2 -、-R a3 COOR a4 -、-R a5 OCOR a6 -、-R a7 OC = OOR a8 -、-N=N-、-CR c =CR d -、or -C≡C-. Here, R a1 ~R a8 Each independently represents a single bond, or an alkylene group having 1 to 4 carbon atoms, Rc and R d L represents an alkyl group or hydrogen atom with 1 to 4 carbon atoms. 1 and L 2 Each independently is more preferably a single bond, -OR a2-1 -、-CH2-、-CH2CH2-、-COOR a4-1 -、or-OCOR a6-1 -. Here, R a2-1 R a4-1 R a6-1 Each can independently represent any one of the following: a single bond, -CH2-, or -CH2CH2-. L 1 and L 2 Each of these can be further preferred independently as a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, or -OCO-.

[0324] B 1 and B 2 Each is preferably a single bond, an alkylene group having 1 to 4 carbon atoms, or an -O-, -S-, or -R group. a9 OR a10 -、-R a11 COOR a12 -、-R a13 OCOR a14 - or -R a15 OC = OOR a16 -. Here, R a9 ~R a16 Each can independently represent a single bond or an alkylene group having 1 to 4 carbon atoms. B 1 and B 2 Each independently is more preferably a single bond, -OR a10-1 -、-CH2-、-CH2CH2-、-COOR a12 -1 -、or-OCOR a14-1 -. Here, R a10-1 R a12-1 R a14-1 Each can independently represent any one of the following: a single bond, -CH2-, or -CH2CH2-. B 1 and B 2 Each of these can be further preferred independently as a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, -OCO-, or -OCOCH2CH2-.

[0325] From the viewpoint of exhibiting inverse wavelength dispersion, k and l are preferably in the range of 2 ≤ k + l ≤ 6, preferably k + l = 4, and more preferably k = 2 and l = 2. If k = 2 and l = 2, it becomes a symmetrical structure, which is therefore preferred. When k is 2 or more, two B 1 They can be the same or different, 2GB 1 They can be the same or different. When l is 2 or more, there are two Bs. 2 They can be the same or different, 2GB 2 They can be the same or different.

[0326] As P 1 or P 2 Examples of polymerizable groups include epoxy, vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, (meth)acryloyl, ethylene oxide, and oxetyl. Among these, (meth)acryloyl, vinyl, and vinyloxy are preferred, and (meth)acryloyl is more preferred.

[0327] Ar preferably has at least one selected from aromatic hydrocarbon rings that may have substituents, aromatic heterocycles that may have substituents, and electron-withdrawing groups. Examples of such aromatic hydrocarbon rings include benzene rings, naphthyl rings, and anthracene rings, with benzene rings and naphthyl rings being preferred. Examples of such aromatic heterocycles include furan rings, benzofuran rings, pyrrole rings, indole rings, thiophene rings, benzothiophene rings, pyridine rings, pyrazine rings, pyrimidine rings, triazole rings, triazine rings, pyrrolidine rings, imidazole rings, pyrazole rings, thiazole rings, benzothiazole rings, thienothiazole rings, oxazole rings, benzoxazole rings, and phenanthroline rings. Among these, a thiazole ring, a benzothiazole ring, or a benzofuran ring is preferred, and a benzothiazole ring is even more preferred. Furthermore, when Ar contains a nitrogen atom, the nitrogen atom preferably has π electrons.

[0328] In formula (B1), N represents the total number of π electrons possessed by the group represented by Ar. π The value is typically 6 or more, preferably 8 or more, more preferably 10 or more, even more preferably 14 or more, and particularly preferably 16 or more. Additionally, it is preferably 36 or less, more preferably 32 or less, even more preferably 26 or less, and particularly preferably 24 or less.

[0329] Examples of aromatic groups contained in Ar include the following groups.

[0330] [Chemical Formula 14]

[0331]

[0332] In equations (Ar-1) to (Ar-23), The mark indicates the connection part, Z 0 Z1 and Z 2 Each of these groups independently represents a hydrogen atom, a halogen atom, an alkyl group (1-12 carbon atoms), a cyano group, a nitro group, an alkylsulfinyl group (1-12 carbon atoms), an alkylsulfonyl group (1-12 carbon atoms), a carboxyl group, a fluoroalkyl group (1-12 carbon atoms), an alkoxy group (1-12 carbon atoms), an alkylthio group (1-12 carbon atoms), an N-alkylamino group (1-12 carbon atoms), an N,N-dialkylamino group (2-12 carbon atoms), an N-alkylaminosulfonyl group (1-12 carbon atoms), or an N,N-dialkylaminosulfonyl group (2-12 carbon atoms). Additionally, Z... 0 Z 1 and Z 2 It can contain polymeric groups.

[0333] In equations (Ar-1) to (Ar-23), Q 1 and Q 2 Each is represented independently - CR 2’ R 3’ -、-S-、-NH-、-NR 2’ -、-CO- or -O-, R 2’ and R 3’ Each can be independently represented as an alkyl group having 1 to 4 hydrogen atoms or carbon atoms.

[0334] In equations (Ar-1) to (Ar-23), J 1 and J 2 Each can be used to represent a carbon atom or a nitrogen atom independently.

[0335] In equations (Ar-1) to (Ar-23), Y 1 Y 2 and Y 3 Each can be independently represented as a substituted aromatic hydrocarbon group or an aromatic heterocyclic group.

[0336] In formula (Ar-1) to formula (Ar-23), W 1 and W 2 Each can independently represent a hydrogen atom, cyano group, methyl group, or halogen atom, and m represents an integer from 0 to 6.

[0337] As Y 1 Y 2 and Y 3 The aromatic hydrocarbon group in the compound can include phenyl, naphthyl, anthraceneyl, phenanthryl, biphenyl, and other aromatic hydrocarbon groups with 6 to 20 carbon atoms, with phenyl and naphthyl being preferred, and phenyl being more preferred. As aromatic heterocyclic groups, can include furanyl, pyrroleyl, thiopheneyl, pyridyl, thiazolyl, benzothiazolyl, and other aromatic heterocyclic groups with 4 to 20 carbon atoms containing at least one heteroatom such as a nitrogen atom, oxygen atom, or sulfur atom, with furanyl, thiopheneyl, pyridyl, thiazolyl, and benzothiazolyl being preferred.

[0338] Y 1 Y 2 and Y 3 Each can be independently a substituted polycyclic aromatic hydrocarbon group or a polycyclic aromatic heterocyclic group. A polycyclic aromatic hydrocarbon group refers to a fused polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. A polycyclic aromatic heterocyclic group refers to a fused polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

[0339] Z 0 Z 1 and Z 2 Each of the following is preferably composed of a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, or an alkoxy group having 1 to 12 carbon atoms. 0 Further preferred are hydrogen atoms, alkyl groups having 1 to 12 carbon atoms, and cyano groups, Z. 1 and Z 2 Further preferred are hydrogen atoms, fluorine atoms, chlorine atoms, methyl groups, and cyano groups. Additionally, Z... 0 Z 1 and Z 2 It can contain polymeric groups.

[0340] Q 1 and Q 2 Preferred types are -NH-, -S-, and -NR. 2’ -、-O-,R 2’ Hydrogen atoms are preferred. Among them, -S-, -O-, and -NH- are particularly preferred.

[0341] Of the formulas (Ar-1) to (Ar-23), formulas (Ar-10) and (Ar-11) are particularly preferred.

[0342] In formula (Ar-16) ~ (Ar-23), Y 1 It can bond with the nitrogen atom and Z 0 Together, they form an aromatic heterocyclic group. Examples of aromatic heterocyclic groups that Ar can possess, as described above, include pyrrole rings, imidazole rings, pyrrololine rings, pyridine rings, pyrazine rings, pyrimidine rings, indole rings, quinoline rings, isoquinoline rings, purine rings, and pyrrolidine rings. This aromatic heterocyclic group may have substituents. Additionally, Y... 1 It can bond with the nitrogen atom and Z 0 Together, these are the aforementioned substituted polycyclic aromatic hydrocarbon groups or polycyclic aromatic heterocyclic groups. Examples include benzofuran rings, benzothiazole rings, and benzoxazole rings.

[0343] The compound shown in formula (B1) can be manufactured, for example, according to the method described in Japanese Patent Application Publication No. 2010-31223.

[0344] From the viewpoint of phase retardation function and thinness, the thickness of the phase retardation film contained in the second phase retardation plate is preferably 0.1 to 5 μm, more preferably 0.5 to 5 μm, even more preferably 0.5 to 3 μm, and even more preferably 1 to 3 μm. When the phase retardation film includes an alignment film, the thickness of the aforementioned phase retardation film does not include the thickness of the alignment film.

[0345] When stacking the polarizer onto the second retardation plate, it is preferable to stack them in such a way that the absorption axis of the polarizer and the slow axis (optical axis) of the second retardation plate are substantially 45° apart. By stacking them in such a way that the absorption axis of the polarizer and the slow axis (optical axis) of the second retardation plate are substantially 45° apart, the function of a circular polarizer can be obtained. The bonding of the polarizer and the second retardation plate can be performed, for example, via a bonding layer formed by an adhesive. As the adhesive, the same adhesive that can be used for bonding the polarizer and the first retardation plate can be used.

[0346] <Any layer>

[0347] In addition to the first phase retardation plate, the polarizing plate, and the second phase retardation plate, the circular polarizing plate of the present invention may optionally include one or more other layers. Examples of such other layers include an adhesive layer for bonding the first phase retardation plate to the polarizing plate, and an adhesive layer for bonding the polarizing plate to the second phase retardation plate. Furthermore, layers that do not impair the function of the circular polarizing plate may be included, as well as adhesive layers for bonding such layers to the first phase retardation plate, the polarizing plate, and / or the second phase retardation plate. The adhesive layer may be the same as the adhesive layer used for bonding the polarizing plate to the first phase retardation plate.

[0348] In one embodiment of the invention, the circular polarizing plate has one or more irregularly shaped processed portions in its plane. In this specification, "irregularly shaped processed portion" refers to a portion processed into a special shape different from the usual processed shape (e.g., a chamfer at a corner). Representative examples of irregularly shaped processed portions include through holes and cutting portions that appear as concave portions when viewed from above. The shape of the through hole is not particularly limited; for example, it can be circular, elliptical, rounded rectangle, or capsule-shaped. Representative examples of concave portions include V-grooves and U-grooves. When the circular polarizing plate has multiple irregularly shaped processed portions, they can be identical or different from each other.

[0349] Typically, cracks are prone to occur in such irregularly shaped machining sections. The circular polarizing plate of the present invention, by sequentially comprising a specific first phase difference plate, a specific polarizing plate, and a specific second phase difference plate, exhibits improved crack resistance (particularly crack resistance during machining of irregularly shaped sections and / or crack resistance after durability tests such as thermal shock tests).

[0350] The irregularly shaped processing section can be placed in any suitable location depending on the purpose. Typically, the irregularly shaped processing section is located at or near the end of the circular polarizing plate.

[0351] The circular polarizer of the present invention enables a display device to operate stably even when the display device equipped with the circular polarizer is placed in a high-temperature environment, and even when the circular polarizer has undergone shape processing or perforation in the display device. Furthermore, in one embodiment of the present invention, the reflectivity of the display device can be reduced. Therefore, the circular polarizer of the present invention is suitable as a component of various display devices.

[0352] A display device is a device that has a display element, including a light-emitting element or light-emitting device as a light source. Examples of display devices include liquid crystal displays (LCDs), organic electroluminescent (EL) displays, inorganic electroluminescent (EL) displays, touch panel displays, electron emission displays (e.g., field emission displays (FEDs) and surface field emission displays (SEDs)), electronic paper (display devices using electronic inks or electrophoretic elements), plasma displays, projection displays (e.g., grating light valve (GLV) displays and displays with digital micromirror devices (DMDs)), and piezoelectric ceramic displays. Liquid crystal displays include transmissive liquid crystal displays, semi-transmissive liquid crystal displays, and reflective liquid crystal displays. This invention relates to any of the following: direct-view liquid crystal display devices and projection liquid crystal display devices. These display devices can be display devices that display two-dimensional images or stereoscopic display devices that display three-dimensional images. In particular, the circular polarizing plate of the present invention can be suitably used in organic electroluminescent (EL) display devices and inorganic electroluminescent (EL) display devices, as well as in liquid crystal display devices and touch panel display devices. Regarding these display devices, the display device incorporating the circular polarizing plate of the present invention can operate stably even when placed in a high-temperature environment, and even when the circular polarizing plate is shaped or perforated in the display device.

[0353] In one embodiment of the present invention, it is preferable that the first phase retardation plate is located on the observation side closer to the second phase retardation plate in the display device. In this embodiment, even if the display device including the circular polarizer of the present invention is placed in a high-temperature environment, and even if the circular polarizer in the display device has undergone shape processing or perforation, the display device can operate more stably.

[0354] In this embodiment, from the viewpoint of the mechanical strength of the surface of the circular polarizer, the outermost surface of the circular polarizer preferably contains a hard coating on the side opposite to the side of the first phase difference plate.

[0355] In one embodiment, when the circular polarizer includes at least one bonding layer, it is preferable that at least one of the bonding layers is a layer formed of adhesive (i.e., an adhesive layer), and more preferably, the entire bonding layer is an adhesive layer. In this embodiment, the reflectivity of the display device including the circular polarizer of the present invention can be reduced. When assembling the circular polarizer of the present invention into the display device, the reflectivity reduction effect can be further improved by positioning the first phase retardation plate closer to the observation side than the second phase retardation plate.

[0356] The present invention will now be described in more detail with examples and comparative examples, but the invention is not limited to these examples. Unless otherwise specified, the amounts used, parts, and percentages of content are indicated on a mass basis.

[0357] Example

[0358] [Measurement]

[0359] 〔thickness〕

[0360] The thickness of the layer or film was measured using a laser microscope ("LEXT" manufactured by Olympus Corporation) or a digital micrometer ("MH-15M" manufactured by Nikon Corporation).

[0361] Glass transition temperature

[0362] The glass transition temperature Tg [°C] of the thermoplastic resin film was determined using a differential scanning calorimeter (Seiko Instruments EXSTAR6000 series DSC6220).

[0363] [Tension modulus of elasticity]

[0364] The tensile modulus of elasticity was determined according to JIS K 7161-1 using the Autograph "AG-IS" manufactured by Shimadzu Corporation. The sample was cut into pieces with a width of 10 mm and a length of 50 mm (excluding the chuck section), and a uniaxial tensile test was performed at a speed of 1 mm / min. The tensile modulus of elasticity was calculated based on the slope of the stress-strain curve obtained from the test.

[0365] [Storage modulus of the adhesive layer]

[0366] Multiple adhesive layers were stacked to a thickness of 0.2 mm (measured using a digital micrometer (Nikon MH-15M)). A cylinder with a diameter of 8 mm was then punched out and used as the test sample. The storage modulus G' [kPa] of this test sample was determined using a viscoelasticity measuring apparatus (Physica MCR300) under the following conditions via the torsional shear method, according to JIS K7244-6.

[0367] <Measurement Conditions>

[0368] Normal force FN: 1N

[0369] Strain γ: 1%

[0370] Frequency: 1Hz

[0371] Temperature: 25℃

[0372] [Pencil Hardness Test]

[0373] The pencil hardness of the first phase difference plate used below was measured using a pencil scratch hardness tester manufactured by Yasuda Seiki Co., Ltd. No. 553-M, in accordance with JIS K5600-5-4.

[0374] [Preparation of Active Energy Ray Curable Composition (Catonic Polymerizable Adhesive Composition)]

[0375] The following components were mixed and degassed to prepare an active energy radiation-curable composition. It should be noted that the photocationic polymerization initiator was formulated as a 50% propylene carbonate solution, and its parts are expressed as solids.

[0376] • Cationic polymerizable compound (1) [3-ethyl-3{[(3-ethyloxetane-3-yl)methoxy]methyl}oxetane (trade name: OXT-221, manufactured by Toa Synthetic Co., Ltd.)]: 60.0 parts

[0377] • Cationic polymeric compound (2) [3,4-epoxycyclohexanecarboxylic acid 3',4'-epoxycyclohexylmethyl ester (trade name: CEL2021P, manufactured by Daicel Co., Ltd.)]: 32.5 parts

[0378] • Cationic polymerizable compound (3) [1,2-epoxy-4-(2-epoxyethylene)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (trade name: EHPE3150, manufactured by Daicel Co., Ltd.)]: 7.5 parts

[0379] • Photocationic polymerization initiator [CPI-100P (manufactured by San-Apro Corporation, 50% by mass solution)]: 2.3 parts

[0380] • Photosensitizer [9,10-dibutoxyanthracene]: 1.0 part

[0381] The energy storage modulus G' of the adhesive layer at 25℃ is 3150MPa.

[0382] [Preparation of the adhesive layer]

[0383] As an adhesive layer, a 5 μm thick (meth)acrylic adhesive layer is prepared through the following steps.

[0384] In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device, and nitrogen inlet tube, 95.0 parts by weight of n-butyl acrylate, 4.0 parts by weight of acrylic acid, 1.0 part by weight of 2-hydroxyethyl acrylate, 200 parts by weight of ethyl acetate, and 0.08 parts by weight of 2,2'-azobisisobutyronitrile were added. The air in the reaction vessel was purged with nitrogen. Under a nitrogen atmosphere, the reaction solution was heated to 60°C with stirring, and after reacting for 6 hours, it was cooled to room temperature. The weight-average molecular weight of a portion of the resulting solution was determined, confirming the formation of a (meth)acrylate polymer of 1.8 million.

[0385] 100 parts by weight of the (meth)acrylate polymer obtained in the above process (conversion value of solid content; the same below), 1.5 parts by weight of trimethylolpropane-modified toluene diisocyanate (manufactured by Tosoh Corporation, trade name "Coronate (registered trademark) L") as an isocyanate-based crosslinking agent, 0.30 parts by weight of 3-epoxypropoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name "KBM403") as a silane coupling agent, 7.5 parts by weight of ethoxylated isocyanurate triacrylate (manufactured by Shin-Nakamura Chemical Industry Co., Ltd., trade name "A-9300") as an ultraviolet curable compound, and 0.5 parts by weight of 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-one (manufactured by BASF Corporation, Irgacure (registered trademark) 907) as a photopolymerization initiator were mixed, stirred thoroughly, and diluted with ethyl acetate to obtain a composition for forming an adhesive layer.

[0386] On the release surface (peel-off layer) of the diaphragm (Lintec Co., Ltd.: SP-PLR382190), the adhesive layer forming composition was applied using an applicator to a thickness of 5 μm after drying. After drying at 100°C for 1 minute, another diaphragm (Lintec Co., Ltd.: SP-PLR381031) was then adhered to the side of the adhesive layer forming composition opposite to the side with which the diaphragm was attached. Using a UV irradiation device with a conveyor belt (Fusion UV Systems, using a D bulb), the dried adhesive layer forming composition was irradiated with UV light (500 mW / cm²) through the diaphragm (SP-PLR38). 2 Cumulative light intensity 500 mJ / cm 2 This yielded an adhesive layer with diaphragms on both sides.

[0387] The energy storage modulus G' of the adhesive layer at 25°C is 106 kPa.

[0388] [Preparation of the composition for photo-alignment film formation]

[0389] Two parts of a photo-oriented polymer with a number-average molecular weight of 28,000 (as shown in the chemical formula below) and 98 parts of o-xylene were mixed, and the resulting mixture was stirred at 80°C for 1 hour to obtain a composition for photo-oriented film formation.

[0390] [Chemical Formula 15]

[0391]

[0392] [In the formula, Me represents methyl]

[0393] [First phase difference plate]

[0394] First phase difference plate A

[0395] A cyclic olefin polymer (COP) membrane (first phase retardation plate A) with an acrylic HC layer (cured resin layer) (3 μm thick) formed on one side of a cyclic olefin polymer (COP) membrane (ZEON Corporation, Japan, "ZD12", 22 μm thick) was prepared. The first phase retardation plate A has an HC layer / COP membrane structure.

[0396] The in-plane phase difference value of the first phase difference plate A was measured using a "KOBRA-WR" manufactured by Oji Measurement Equipment Co., Ltd., and the results are as follows:

[0397] The in-plane phase difference Re1(450) at a wavelength of 450 nm is 105 nm.

[0398] The in-plane phase difference Re1(550) at a wavelength of 550 nm is 100 nm.

[0399] The in-plane phase difference Re1(650) at a wavelength of 650nm is 96nm.

[0400] The ratio of Re1(450) / Re1(550) was calculated to be 1.05, and the ratio of Re1(650) / Re1(550) was calculated to be 0.96. Therefore, it is confirmed that the COP film in the first phase retardation plate A has positive wavelength dispersion. It should be noted that since the HC layer in the first phase retardation plate A does not exhibit phase difference, it will not affect the in-plane phase difference value.

[0401] The COP film in the first retardation plate A has a glass transition temperature of 131°C and a tensile modulus of elasticity of 2200 MPa. Additionally, the pencil hardness of the HC layer in the first retardation plate A is 2B.

[0402] First phase difference plate B

[0403] A uniaxially stretched triacetyl cellulose (TAC) membrane, as described in Japanese Patent Application Publication No. 2023-167428, was obtained. This membrane was used as a first retardation plate B (stretched TAC membrane) with a thickness of 25 μm. The first retardation plate B consisted of only a single layer of stretched TAC.

[0404] The in-plane phase difference value of the first phase difference plate was measured using a "KOBRA-WR" manufactured by Oji Measurement Equipment Co., Ltd., and the results are as follows:

[0405] The in-plane phase difference Re1(450) at a wavelength of 450 nm is 103 nm.

[0406] The in-plane phase difference Re1(550) at a wavelength of 550 nm is 105 nm.

[0407] The in-plane phase difference Re1(650) at a wavelength of 650nm is 107nm.

[0408] The ratio Re1(450) / Re1(550) was calculated to be 0.98, and the ratio Re1(650) / Re1(550) was calculated to be 1.02. Therefore, it was confirmed that the stretched TAC monolayer, which serves as the first phase difference plate B, has inverse wavelength dispersion.

[0409] The glass transition temperature of the tensile TAC monolayer used as the first retardation plate B is 180°C, and the tensile modulus of elasticity is 4000 MPa. Furthermore, the pencil hardness of the surface of the first retardation plate B is 5B.

[0410] First phase difference plate C

[0411] A triacetylcellulose membrane (first phase retardation plate C) with an acrylic HC layer (cured resin layer) (thickness 3 μm) formed on one side of the first phase retardation plate B was prepared. The first phase retardation plate C has an HC layer / stretched TAC membrane structure.

[0412] The in-plane phase difference value of the first phase difference plate C was measured using a "KOBRA-WR" manufactured by Oji Measurement Equipment Co., Ltd., and the results are as follows:

[0413] The in-plane phase difference Re1(450) at a wavelength of 450 nm is 103 nm.

[0414] The in-plane phase difference Re1(550) at a wavelength of 550 nm is 105 nm.

[0415] The in-plane phase difference Re1(650) at a wavelength of 650nm is 107nm.

[0416] The ratio of Re1(450) / Re1(550) was calculated to be 0.98, and the ratio of Re1(650) / Re1(550) was calculated to be 1.02. Therefore, it is confirmed that the stretched TAC film in the first phase retardation plate C has reverse wavelength dispersion. It should be noted that since the HC layer in the first phase retardation plate C does not exhibit phase difference, it will not affect the in-plane phase difference value.

[0417] The glass transition temperature of the stretched TAC film in the first retardation plate C is 180°C, and the tensile modulus is 4000 MPa. Additionally, the pencil hardness of the HC surface of the first retardation plate C is H.

[0418] First phase difference plate D

[0419] A triacetyl cellulose (TAC) membrane with an acrylic HC layer (cured resin layer) (3 μm thick) was prepared on one side of a 25 μm thick triacetyl cellulose (TAC) membrane manufactured by Konica Minolta Corporation. Furthermore, according to Example 1 of Japanese Patent Application Publication No. 2021-124641, a phase retardation film forming composition (a composition containing a polymerizable liquid crystal compound) was coated onto the release-treated side of the TAC membrane after a release treatment and dried, causing the polymerizable liquid crystal compound contained in the dried coating to polymerize, thereby producing a laminate of the TAC membrane and the phase retardation film. After plasma treatment of the TAC surface of the HC-TAC membrane and the phase retardation film surface of the laminate, they were bonded and laminated using the adhesive layer prepared above. Then, the TAC membrane on the phase retardation film side was peeled off, thereby obtaining a first phase retardation plate D. The first phase retardation plate D has a layer structure of HC layer / TAC membrane / adhesive layer / phase retardation film.

[0420] The in-plane phase difference value of the first phase difference plate D was measured using a "KOBRA-WR" manufactured by Oji Measurement Equipment Co., Ltd., and the results are as follows:

[0421] The in-plane phase difference Re1(450) at a wavelength of 450 nm is 125 nm.

[0422] The in-plane phase difference Re1(550) at a wavelength of 550 nm is 113 nm.

[0423] The in-plane phase difference Re1(650) at a wavelength of 650nm is 108nm.

[0424] The ratio of Re1(450) / Re1(550) was calculated to be 1.11, and the ratio of Re1(650) / Re1(550) was calculated to be 0.96. Therefore, it is confirmed that the phase retardation film in the first phase retardation plate D has positive wavelength dispersion. It should be noted that since the HC layer, TAC film and adhesive layer in the first phase retardation plate D do not exhibit phase difference, they will not affect the in-plane phase difference value.

[0425] The TAC film in the first retardation plate D has a glass transition temperature of 180°C and a tensile modulus of elasticity of 4000 MPa. Additionally, the pencil hardness of the HC surface of the first retardation plate D is H.

[0426] First phase difference plate E

[0427] A triacetyl cellulose (TAC) membrane with an acrylic HC layer (curing resin layer) (3 μm thick) was prepared on one side of a 25 μm thick triacetyl cellulose (TAC) membrane manufactured by Konica Minolta Corporation. Furthermore, according to Example 1 of Japanese Patent Application Publication No. 2021-124641, a phase retardation film forming composition (a composition containing a polymerizable liquid crystal compound) was coated onto the release-treated side of the TAC membrane after a release treatment and dried, causing the polymerizable liquid crystal compound contained in the dried coating to polymerize, thereby producing a laminate of the TAC membrane and the phase retardation film. After plasma treatment of the TAC surface of the HC-TAC membrane and the phase retardation film surface of the laminate, the aforementioned active energy radiation curable composition (cationic polymerizable adhesive composition) was coated onto the TAC surface of the HC-TAC membrane, making the adhesive layer thickness 2 μm, and the coated surface was then bonded to the phase retardation film surface of the laminate. Then, using a UV irradiation device with a conveyor belt (manufactured by Fusion UV Systems, using D bulbs), ultraviolet light (irradiation intensity 500mW / cm²) was applied through the TAC film of the aforementioned laminate to irradiate it. 2 Cumulative light intensity 500 mJ / cm 2The TAC film of the above-mentioned laminate is peeled off to obtain the first retardation plate E. The first retardation plate E is composed of an HC layer / TAC film / adhesive layer / retardation film.

[0428] The in-plane phase difference value of the first phase difference plate E was measured using a "KOBRA-WR" manufactured by Oji Measurement Equipment Co., Ltd., and the results are as follows:

[0429] The in-plane phase difference Re1(450) at a wavelength of 450 nm is 125 nm.

[0430] The in-plane phase difference Re1(550) at a wavelength of 550 nm is 113 nm.

[0431] The in-plane phase difference Re1(650) at a wavelength of 650nm is 108nm.

[0432] The ratio of Re1(450) / Re1(550) was calculated to be 1.11, and the ratio of Re1(650) / Re1(550) was calculated to be 0.96. Therefore, it is confirmed that the phase retardation film in the first phase retardation plate E has positive wavelength dispersion. It should be noted that since the HC layer, TAC film and adhesive layer in the first phase retardation plate E do not exhibit phase difference, they will not affect the in-plane phase difference value.

[0433] The TAC film in the first retardation plate E has a glass transition temperature of 180°C and a tensile modulus of elasticity of 4000 MPa. Additionally, the pencil hardness of the HC surface of the first retardation plate E is H.

[0434] First phase difference plate F

[0435] A triacetyl cellulose (TAC) membrane (HC-TAC membrane) with an acrylic HC layer (cured resin layer) (20cm × 30cm × 3μm thickness) was prepared on one side of a triacetyl cellulose (TAC) membrane (25μm thickness) manufactured by Konica Minolta Corporation. After plasma treatment of the TAC side of the HC-TAC membrane, the following photo-alignment polymer composition (1) was coated onto it. The resulting coated membrane was dried at 120°C for 2 minutes and then cooled to room temperature to form a dried film. Furthermore, using a UV irradiation device, 100mJ of polarized ultraviolet light (313nm reference) was continuously irradiated at a 45° angle relative to the length direction of the HC-TAC membrane to form a 100nm photo-alignment film. The following phase retardation film forming composition (1) was coated onto it using a bar coater. The resulting coated membrane was dried at 100°C for 1 minute and then cooled to room temperature to obtain a dried film. Next, the above-mentioned dried film was continuously irradiated with an exposure dose of 1000mJ / cm under a nitrogen atmosphere using a high-pressure mercury lamp. 2Ultraviolet light (365nm reference) is used to solidify a polymeric liquid crystal compound in a horizontally oriented state relative to the substrate surface to form a retardation film, thereby obtaining a first retardation plate F. The first retardation plate F has a layer structure of HC layer / TAC film / orientation film / retardation film.

[0436] Preparation of photooriented polymer composition (1)

[0437] A photooriented material with the following structure (weight average molecular weight: 50,000, m:n = 50:50) was prepared according to the method described in Japanese Patent Application Publication No. 2021-196514. Two parts of the photooriented material and 98 parts of propylene glycol monomethyl ether (PGME, solvent) were mixed, and the resulting mixture was stirred at 80°C for 1 hour to prepare a photooriented polymer composition (1).

[0438] Photooriented materials:

[0439] [Chemical Formula 16]

[0440]

[0441] Preparation of composition (1) for phase difference film formation

[0442] A composition (1) for phase retardation film formation was prepared by adding leveling agent "BYK-361N" (manufactured by BYK-Chemie), photopolymerization initiator "Omnirad907" (manufactured by IGM Resin BV), and additive "Laromer (registered trademark) LR-9000" (manufactured by BASF Japan) to the polymerizable liquid crystal compound Paliocolor (registered trademark) LC242 (manufactured by BASF Japan) shown below. Additionally, propylene glycol 1-monomethyl ether 2-acetic acid (PGME) was added. The mixture was stirred at 80°C for 1 hour. The amounts of each component added are shown in Table 1 below.

[0443]

[0444] Paliocolor (registered trademark), a polymerizable liquid crystal compound: LC242

[0445] [Chemical Formula 17]

[0446]

[0447] The in-plane phase difference value of the first phase difference plate F was measured using a "KOBRA-WR" manufactured by Oji Measurement Equipment Co., Ltd., and the results are as follows:

[0448] The in-plane phase difference Re1(450) at a wavelength of 450 nm is 102 nm.

[0449] The in-plane phase difference Re1(550) at a wavelength of 550 nm is 95 nm.

[0450] The in-plane phase difference Re1(650) at a wavelength of 650nm is 93nm.

[0451] The ratio of Re1(450) / Re1(550) was calculated to be 1.07, and the ratio of Re1(650) / Re1(550) was calculated to be 0.98. Therefore, it is confirmed that the phase retardation film in the first phase retardation plate F has positive wavelength dispersion. It should be noted that since the HC layer, TAC film and alignment film in the first phase retardation plate F do not exhibit phase difference, they will not affect the in-plane phase difference value.

[0452] The TAC film in the first retardation plate F has a glass transition temperature of 180°C and a tensile modulus of elasticity of 4000 MPa. Additionally, the pencil hardness of the HC surface of the first retardation plate F is H.

[0453] [Linear polarizer]

[0454] (Preparation of polymeric liquid crystal compositions for forming linear polarizing films)

[0455] The following components were mixed and stirred at 80°C for 1 hour to obtain a polymerizable liquid crystal composition. The polymerizable liquid crystal compounds (X1) and (X2) have the structures shown below. The dichroic pigments (DP1) to (DP3) are the azo pigments described in the examples of Japanese Patent Application Publication No. 2013-101328, and have the structures shown below.

[0456] Polymerizable liquid crystal compound (X1): 75 parts

[0457] Polymerizable liquid crystal compound (X2): 25 parts

[0458] Dichroic pigment (DP1): 2.5 parts

[0459] Dichroic pigment (DP2): 2.5 parts

[0460] Dichroic pigment (DP3): 2.5 parts

[0461] Polymerization initiator [2-Dimethylamino-2-benzyl-1-(4-morpholinophenyl)butane-1-one (Irgacure (registered trademark) 369; manufactured by BASF Japan): 6 parts

[0462] Leveling agent [polyacrylate compound (BYK-361N; manufactured by BYK-Chemie)]: 1.2 parts

[0463] Solvent [o-xylene]: 250 parts

[0464] • Polymerizable liquid crystal compound (X1):

[0465] [Chemical Formula 18]

[0466]

[0467] • Polymerizable liquid crystal compound (X2):

[0468] [Chemical Formula 19]

[0469]

[0470] • Dichroic pigment (DP1):

[0471] [Chemical Formula 20]

[0472]

[0473] ·Dichroic pigment (DP2):

[0474] [Chemical Formula 21]

[0475]

[0476] ·Dichroic pigment (DP3):

[0477] [Chemical Formula 22]

[0478]

[0479] (Preparation of the composition for HC layer formation)

[0480] The following components were mixed and stirred at 50°C for 4 hours to obtain a composition for HC layer formation.

[0481] • Acrylic ester monomers as shown in the following chemical formula: 70 parts

[0482] [Chemical Formula 23]

[0483]

[0484] • 30 parts of urethane acrylate resin [EBECRYL4858 (manufactured by Daicel Allnex Co., Ltd.)]

[0485] • Polymerization initiator [Omnirad 907 (manufactured by IGM Resins BV)]: 3 parts

[0486] • Solvent [methyl ethyl ketone]: 10 parts

[0487] (Preparation of the composition (water-soluble polymer aqueous solution) for forming the outer coating)

[0488] A water-soluble polymer containing the following structural units was obtained according to the following synthesis scheme.

[0489] [Chemical Formula 24]

[0490]

[0491] 20 g of polyvinyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.) with a molecular weight of 1000, 0.55 mg of N,N-dimethyl-4-aminopyridine (as a nucleophile), and 4.6 g of triethylamine were dissolved in 400 g of dimethyl sulfoxide, and the mixture was heated to 60°C while stirring. Then, a solution containing 10.5 g of methacrylic anhydride dissolved in 50 g of dimethyl sulfoxide was added dropwise over 1 hour, and the mixture was heated and stirred at 60°C for 14 hours to induce a reaction. After cooling the resulting reaction solution to room temperature, 481 g of methanol was added to the reaction solution and stirred until a 1:1 mass ratio of reaction solution to methanol was achieved. The water-soluble polymer was crystallized by gradually adding 1500 mL of acetone to the solution. The resulting solution containing white crystals was filtered, thoroughly washed with acetone, and then vacuum dried to obtain 20.2 g of the water-soluble polymer. The obtained water-soluble polymer was dissolved in water to prepare a 3% (w / w) water-soluble polymer aqueous solution.

[0492] (Fabrication of a linear polarizing plate)

[0493] On the release treatment surface of a roll of 800mm wide release polyethylene terephthalate (PET) film (Unitika Co., Ltd. "FF-50", single-sided release PET film (support substrate thickness: 50μm)), the above-mentioned HC layer forming composition was continuously coated using a slit-type die coater, and dried at 100°C for 2 minutes to form an HC layer with a thickness of 2.00μm. Thus, a film with an HC layer laminated on the release treatment surface of the single-sided release PET film was obtained, which was used as the first substrate layer.

[0494] After plasma treatment of the HC layer of the first substrate layer, the photo-aligned film forming composition prepared above was coated using a slit-type die coater, forming a coating layer with a width of 600 mm in the center of the single-sided demolded PET film. Next, the coating layer on the HC layer was dried by conveying it in a ventilated drying oven at 100°C for 2 minutes to remove the solvent. Then, the dried coating layer was subjected to a strength of 20 mJ / cm². 2Polarized UV light at an intensity of 313 nm (reference value) is applied to the PET film undergoing single-sided demolding treatment at a 90° angle to its length direction, thereby imparting an orientation constraint force and forming a photoalignment film on the HC layer. The thickness of the photoalignment film is approximately 50 nm.

[0495] On the photoalignment film formed on the first substrate layer, the polymeric liquid crystal composition prepared above for forming a linear polarizing film was coated using a slit-type die coater, forming a coating layer with a width of 600 mm in the central part of the first substrate layer. Next, the coating layer on the first substrate layer was dried by conveying it in a ventilated drying oven at a temperature set to 110°C for 2 minutes to remove the solvent. Then, a high-pressure mercury lamp at 1000 mJ / cm² was used to dry the coating layer. 2 Irradiation with ultraviolet light (at a 365nm reference) cures the polymeric liquid crystal compound contained in the dried coating layer, thereby forming a cured layer of the polymeric liquid crystal composition for forming a linear polarization film. This results in a liquid crystal polarization film with a substrate layer, on which a photoalignment film and a cured layer (together forming a liquid crystal polarization film) are sequentially formed on a first substrate layer. The liquid crystal polarization film with the substrate layer has an absorption axis in a direction 90° relative to its length. The thickness of the cured layer is 3 μm.

[0496] Next, after plasma treatment of the liquid crystal polarizing film side of the liquid crystal polarizing film with substrate layer, the water-soluble polymer aqueous solution prepared above was continuously coated using a slit-type die coater, and dried at 100°C for 2 minutes to form an outer coating with a thickness of 2 μm. Thus, a strip of linear polarizing plate with substrate layer was obtained, consisting of a first substrate layer (single-sided release-treated PET film / HC layer), a liquid crystal polarizing film (photoalignment film / cured layer), and an outer coating. The single-sided release-treated PET film was peeled off from the obtained linear polarizing plate with substrate layer and used as a linear polarizing plate.

[0497] In addition, the linear polarizing plate before peeling off the single-sided release-treated PET film was cut into squares of 40mm × 40mm. The outer coating side was then attached to an alkali-free glass plate (Corning Corporation, trade name "Eagle-XG") using an acrylic adhesive (Lintec Co., Ltd., trade name "P-3132") with a thickness of 25μm. The single-sided release-treated PET film was then peeled off to obtain the test specimen.

[0498] The single-cell transmittance (T1) along the transmission axis (orientation perpendicular direction) and the single-cell transmittance (T2) along the absorption axis (orientation direction) of the obtained test specimens were measured using a spectrophotometer (Shimadzu Corporation UV-3150) with a support equipped with a linear polarizer, in a wavelength range of 380–680 nm with a 2 nm step size, by a two-beam method. The single-cell transmittance and polarization degree at each wavelength were calculated using the following equations (15) and (16), and visibility correction was further performed using the 2-degree field of view (C light source) of JISZ 8701, thereby calculating the visibility-corrected single-cell transmittance (Ty) and the visibility-corrected polarization degree (Py).

[0499] Monomer transmittance [%] = (T1 + T2) / 2 (15)

[0500] Degree of polarization [%] = [(T1-T2) / (T1+T2)] × 100 (16)

[0501] The results confirmed that the visibility-corrected monomer transmittance (Ty) of the test specimen was 42%, and the visibility-corrected polarization degree (Py) was 97%, which are useful values ​​for use as a polarizer. Furthermore, after heating the test specimen at 100°C for 120 hours, the visibility-corrected monomer transmittance (Ty) and visibility-corrected polarization degree (Py) were calculated using the same procedure. The results showed that the visibility-corrected monomer transmittance (Ty) of the heated test specimen was also 42%, and the visibility-corrected polarization degree (Py) was also 97%, with no decrease in optical performance observed.

[0502] [Second phase difference plate]

[0503] (Preparation of the composition for phase retardation film formation)

[0504] The following components were mixed and stirred at 80°C for 1 hour to obtain a composition for phase retardation film formation.

[0505] • Polymerizable liquid crystal: Compound (A11-1): 80 parts

[0506] [Chemical Formula 25]

[0507]

[0508] • Polymerizable liquid crystal: compound (x-1): 20 parts

[0509] [Chemical Formula 26]

[0510]

[0511] • Polymerization initiator: 2-Dimethylamino-2-benzyl-1-(4-morpholinophenyl)butane-1-one (Irgacure 369; manufactured by BASF Japan): 8 parts

[0512] Leveling agent: Polyacrylate compound (BYK-361N; manufactured by BYK-Chemie): 0.1 parts

[0513] • Other additives: LALOMER LR9000 (manufactured by BASF Japan): 6.7 parts

[0514] Solvent: Cyclopentanone: 546 parts

[0515] Solvent: N-methylpyrrolidone: 364 parts

[0516] (Fabrication of liquid crystal phase retardation film)

[0517] On the release treatment surface of a roll of 800mm wide release polyethylene terephthalate (PET) film (Unitika Co., Ltd. "FF-50", single-sided release PET film, support substrate thickness: 50μm), the aforementioned photo-alignment film forming composition was coated in a 600mm wide area in the center of the film using a slit-type die coater. The resulting coating was dried at 120°C for 2 minutes and then cooled to room temperature to form a dried coating. The dried coating was then irradiated with 100mJ / cm² at an angle of 0° relative to the conveying direction (strip direction) of the strip film. 2 Polarized ultraviolet light (based on 313nm) forms a long strip of photoalignment film. The thickness of the photoalignment film is 50nm.

[0518] On the photoalignment film, the aforementioned composition for forming a phase retardation film was applied to a 600mm wide area in the center of the film using a slit-type die coater, forming a coating film. This coating film was then heated and dried at 120°C for 2 minutes, followed by cooling to room temperature, forming a dried coating film. The dried coating film was then irradiated with 1000mJ / cm² of ultraviolet light. 2 Ultraviolet light (365nm reference) was used to form a liquid crystal retardation film. The thickness of the liquid crystal retardation film was 2.1μm. Thus, a second retardation plate with a release PET film, consisting of a strip containing a release PET film, a photoalignment film, and a liquid crystal retardation film, was obtained.

[0519] The release PET film was peeled off from the second phase difference plate with the release PET film attached. The in-plane phase difference value of the second phase difference plate was measured using a "KOBRA-WR" manufactured by Oji Measurement Equipment Co., Ltd. The results are as follows:

[0520] The in-plane phase difference Re2(450) at a wavelength of 450 nm is 118 nm.

[0521] The in-plane phase difference Re2(550) at a wavelength of 550 nm is 140 nm.

[0522] The in-plane phase difference Re2(650) at a wavelength of 650nm is 146nm.

[0523] The ratio of Re2(450) / Re2(550) was calculated to be 0.84, and the ratio of Re2(650) / Re2(550) was calculated to be 1.04. Therefore, it is confirmed that the liquid crystal phase retardation film in the second phase retardation plate has reverse wavelength dispersion. It should be noted that since the photo-alignment film in the second phase retardation plate does not exhibit phase difference, it will not affect the in-plane phase difference value.

[0524] [Fabrication of optical laminate A (circular polarizer A)]

[0525] The first phase retardation plate A, the adhesive layer, the linear polarizer, the adhesive layer, and the second phase retardation plate with a release PET film prepared above are sequentially stacked. The release PET film is then peeled off, thereby obtaining the optical laminate A. The first phase retardation plate is stacked with the COP film side and the adhesive layer, the linear polarizer is stacked with the HC layer on the side of the first phase retardation plate A, and the second phase retardation plate is stacked with the liquid crystal phase retardation film side and the adhesive layer. At this time, the slow axis of the first phase retardation plate A is stacked at a 45° angle to the absorption axis of the linear polarizer, and the absorption axis of the linear polarizer is stacked at a 45° angle to the slow axis of the second phase retardation plate.

[0526] In optical laminate A, the phase difference Re1(550) of the first phase retardation plate at a wavelength of 550 nm is 100 nm, and the phase difference Re2(550) of the second phase retardation plate at a wavelength of 550 nm is 140 nm. Therefore, it is confirmed that optical laminate A satisfies the following equation (1):

[0527] Re1(550) < Re2(550) Equation (1).

[0528] [Fabrication of optical laminates B-F (circular polarizers B-F)]

[0529] First phase retardation plates B through F were used to replace first phase retardation plate A, and optical laminates B through F were fabricated in the same manner as optical laminate A. In the fabrication of optical laminate C, the stretchable TAC side of first phase retardation plate C was laminated with an adhesive layer. In the fabrication of optical laminates D through F, the phase retardation film side of first phase retardation plates D through F was laminated with an adhesive layer.

[0530] In optical stacks B and C, the phase difference Re1(550) of the first retardation plate at a wavelength of 550 nm is 105 nm, and the phase difference Re2(550) of the second retardation plate at a wavelength of 550 nm is 140 nm. In optical stacks D and E, the phase difference Re1(550) of the first retardation plate at a wavelength of 550 nm is 113 nm, and the phase difference Re2(550) of the second retardation plate at a wavelength of 550 nm is 140 nm. In optical stack F, the phase difference Re1(550) of the first retardation plate at a wavelength of 550 nm is 95 nm, and the phase difference Re2(550) of the second retardation plate at a wavelength of 550 nm is 140 nm. Therefore, it is confirmed that optical stacks B to F satisfy the following equation (1):

[0531] Re1(550) < Re2(550) Equation (1).

[0532] [Fabrication of the optical laminate G (circular polarizer G)]

[0533] Plasma treatment was performed on the phase retardation film surface of the first phase retardation plate E and the HC layer of the linear polarizer prepared above. The aforementioned active energy radiation-curable composition (cationic polymeric adhesive composition) was coated onto the phase retardation film surface of the first phase retardation plate E with an adhesive layer thickness of 2 μm, and this coated surface was then bonded to the HC layer of the linear polarizer. The resulting laminate was irradiated with an exposure dose of 400 mJ / cm² from the linear polarizer side using an ultraviolet irradiation device. 2 (Based on 365nm) ultraviolet light was used to obtain a laminate consisting of a first retardation plate E (HC layer / TAC film / adhesive layer / retardation film), an adhesive layer, and a linear polarizer (HC layer / liquid crystal polarizing film (photoalignment film / cured layer) / outer coating). Using this laminate to replace the first retardation plate A, the adhesive layer, and the linear polarizer, and otherwise operating in the same manner as optical laminate A, an optical laminate G was obtained. The laminates were then stacked such that the slow axis of the first retardation plate E was at a 45° angle to the absorption axis of the linear polarizer, and the absorption axis of the linear polarizer was at a 45° angle to the slow axis of the second retardation plate.

[0534] In the optical stack G, the phase difference Re1(550) of the first phase retardation plate at a wavelength of 550 nm is 113 nm, and the phase difference Re2(550) of the second phase retardation plate at a wavelength of 550 nm is 140 nm. Therefore, it is confirmed that the optical stack A satisfies the following equation (1):

[0535] Re1(550) < Re2(550) Equation (1).

[0536] [Fabrication of the optical laminate H (circular polarizer H)]

[0537] The first phase retardation plate E was replaced by the first phase retardation plate F. Otherwise, the optical stack H was fabricated in the same manner as the optical stack G.

[0538] In the optical stack H, the phase difference Re1(550) of the first phase retardation plate at a wavelength of 550 nm is 95 nm, and the phase difference Re2(550) of the second phase retardation plate at a wavelength of 550 nm is 140 nm. Therefore, it is confirmed that the optical stack A satisfies the following equation (1):

[0539] Re1(550) < Re2(550) Equation (1).

[0540] Evaluation of Optical Laminates (Circular Polarizing Plates)

[0541] <Performance of the first phase retardation plate after high-temperature exposure>

[0542] Optical laminates A through H were each cut into 100×100mm pieces and heated in a 120°C constant temperature bath for 1 minute. After being removed from the constant temperature bath, the in-plane phase difference value of the first phase difference plate of optical laminates A through H was measured using a "KOBRA-WR" manufactured by Oji Measurement & Testing Co., Ltd., and compared with the in-plane phase difference value of the raw materials used in optical laminates A through H.

[0543] The case where the rate of change of phase difference at 550nm is 0% to 5% is rated as "A", the case where it is 5% to 15% is rated as "B", the case where it is 15% to 25% is rated as "C", and the case where it is above 25% is rated as "D".

[0544] <Evaluation of Crack Resistance>

[0545] Optical laminates A through H were cut into 70×90mm pieces. A 6mm φ through-hole was created in the center of each optical laminate using a UV laser (KEYENCE 3-Axis YVO4 laser marking machine "MD-V9900A"). Using an adhesive of the same shape as the optical laminate with the through-hole, the optical laminate with the through-hole was attached to an alkali-free glass plate (Corning, trade name "Eagle-XG"), thus obtaining samples for evaluating crack resistance. These samples were then placed in an autoclave and subjected to a thermal shock test, exposed at -40°C for 30 minutes, followed by exposure at 85°C for 30 minutes.

[0546] After exposing the samples to 50 cycles of -40℃ for 30 minutes and 85℃ for 30 minutes, the appearance of the optical laminates A to H was evaluated by microscopic observation. The condition where no cracks were formed in the through-hole area was rated "A", the condition where cracks smaller than 50 μm were formed was rated "B", the condition where cracks larger than 50 μm but smaller than 100 μm were formed was rated "C", and the condition where cracks larger than 100 μm were formed was rated "D".

[0547] It should be noted that no cracks were formed in any of the samples before the thermal shock test was conducted.

[0548] <Evaluation of Reflectivity>

[0549] The second retardation plate side of optical laminates A to H was bonded to an aluminum reflector via an adhesive layer. A cover glass was then placed on the surface side via adhesive. After autoclaving, reflectance was measured using a Konica Minolta CM-26d spectrophotometer. The SCI value of the Y stimulus was used as the reflectance. A reflectance of 5.0%–5.2% was rated as "A", 5.2%–5.3% as "B", and 5.3%–5.5% as "C".

[0550] <Indentation Test>

[0551] Indentation tests simulating foreign objects and external indentation during winding were conducted. Specifically, firstly, optical laminates A to H were cut into 40×40mm pieces. Next, an indentation test using an Ericsson pen was performed on the surface of the first retardation plate side of each optical laminate.

[0552] After indentation with an Erickson pen, the following criteria are used to evaluate the condition of the indentation formed on the outermost surface: "A" is defined as the case where no indentation remains immediately after the 1N Erickson pen test; "B" is defined as the case where an indentation remains immediately after the 1N Erickson pen test, but is largely restored upon reconfirmation after 10 minutes; and "C" is defined as the case where an indentation remains and does not disappear after 10 minutes.

[0553] The results of the above evaluation items are summarized in the table below.

[0554]

Claims

1. A circular polarizing plate, comprising, in sequence, a first phase difference plate, a polarizing plate, and a second phase difference plate. The first phase retardation plate comprises a thermoplastic resin layer having a glass transition temperature of 150°C or higher and a tensile modulus of elasticity of 3500 MPa or higher. The polarizing plate comprises a cured layer of a polymeric liquid crystal composition containing a polymeric liquid crystal compound and a dichroic pigment. The second phase retardation plate comprises a cured layer of a polymeric liquid crystal composition containing a polymeric liquid crystal compound.

2. The circular polarizing plate according to claim 1, wherein, The phase difference Re1 (550) of the first phase difference plate at a wavelength of 550 nm and the phase difference Re2 (550) of the second phase difference plate at a wavelength of 550 nm satisfy the following equation (1): Re1(550) < Re2(550) Equation (1).

3. The circular polarizing plate according to claim 1, wherein, The thermoplastic resin layer exhibits reverse wavelength dispersion.

4. The circular polarizing plate according to claim 1, wherein, The first retardation plate includes the thermoplastic resin layer and a retardation film that exhibits positive wavelength dispersion.

5. The circular polarizing plate according to claim 1, wherein, The cured layer contained in the second phase difference plate exhibits reverse wavelength dispersion.

6. The circular polarizing plate according to claim 1, wherein, A cured resin layer is also included on the side of the first phase difference plate opposite to the polarizer side.

7. The circular polarizing plate according to claim 1, wherein, The circular polarizing plate has irregularly shaped machining parts within its surface.

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