Polarizing plate and circularly polarizing plate comprising same

Abstract

To provide a polarizing plate which hardly curls and a circularly polarizing plate including the polarizing plate.SOLUTION: A polarizing plate comprising a polarizing film and a protective layer adjacent to the polarizing film, wherein the polarizing film comprises a cured product of a polymerizable liquid crystal composition comprising a polymerizable liquid crystal compound and a dichroic dye and has a thickness of 0.1 to 5 μ m, and the protective layer is a cured product layer of a curable composition comprising a cationic polymerizable compound and has a thickness of 0.2 to 3 μm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polarizing plate and a circular polarizing plate including the polarizing plate. [Background technology]

[0002] Conventionally, polarizing plates are used by being attached to image display elements such as liquid crystal cells or organic EL display elements in various image display panels such as liquid crystal display panels and organic electroluminescence (organic EL) display panels. In recent years, there has been a continuous demand for thinner displays such as image display panels, and further thinner polarizing plates and polarizers, which are one of the components thereof, are also required. In response to this demand, for example, a thin host-guest polarizer made of a polymerizable liquid crystal compound and a compound exhibiting dichroism has been proposed. For example, Patent Document 1 listed below discloses a laminate including a polarizing plate with a linear polarizing layer and a pressure-sensitive adhesive layer, the laminate having a protective film on one and / or both sides of the linear polarizing layer, and Patent Document 2 listed below discloses a polarizing film having a resin layer on each side of a polarizer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-062652 [Patent Document 2] Japanese Patent Publication No. 2020-56834 Summary of the Invention [Problem to be solved by the invention]

[0004] It has been found that when attempting to thin a polarizing plate having a polarizing film and a protective layer adjacent to the polarizing film, curling may occur during production of the polarizing plate depending on the materials constituting each layer of the polarizing plate. Such curled polarizing plates are difficult to handle when producing an image display device or the like that includes the polarizing plate, and may be difficult to transfer to a transfer target material. In particular, polarizing plates having thin polarizing films and protective layers tend to curl more easily, and the demand for curl suppression is increasing along with the demand for thinner polarizing plates.

[0005] Therefore, an object of the present invention is to provide a polarizing plate that is less likely to curl and a circularly polarizing plate that includes the polarizing plate. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that the above-mentioned problems can be solved by a polarizing plate including a specific polarizing film and a specific protective layer adjacent to the polarizing film, thereby completing the present invention.

[0007] That is, the present invention includes the following preferred embodiments. [1] A polarizing plate including a polarizing film and a protective layer adjacent to the polarizing film, the polarizing film contains a cured product of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye, and has a thickness of 0.1 to 5 μm; the protective layer is a cured layer of a curable composition containing a cationically polymerizable compound and has a thickness of 0.2 to 5 μm; Polarizing plate. [2] The polarizing plate according to [1], wherein the cationically polymerizable compound includes a polymerizable compound having a cyclic ether structure. [3] The polarizing plate according to [1] or [2], wherein the protective layer has an in-plane average refractive index of 1.50 to 1.55. [4] The polarizing plate according to any one of [1] to [3], wherein the polarizing film is a horizontal polarizing film. [5] The polarizing plate according to any one of [1] to [4], wherein the protective layer is the outermost layer of the polarizing plate. [6] The polarizing plate according to any one of [1] to [5], wherein the cationically polymerizable compound includes a polymerizable compound having an oxetane ring. [7] The polarizing plate according to any one of [1] to [6], further comprising a cured resin layer on the side of the polarizing film opposite to the side adjacent to the protective layer. [8] The polarizing plate according to [7], wherein the cured resin layer is a cured product layer of a curable resin composition containing a polyfunctional (meth)acrylate compound, and has a thickness of 0.1 to 5 μm. [9] A circularly polarizing plate in which the polarizing plate according to any one of [1] to [8] and a retardation film are laminated via an attachment layer, wherein the protective layer of the polarizing plate, the attachment layer, and the retardation film are adjacent in this order.

[10] The circularly polarizing plate according to [9], wherein the attachment layer has a thickness of 1 to 10 μm.

[11] The circularly polarizing plate according to [9] or

[10] , wherein the retardation film has a thickness of 0.1 to 5 μm. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a polarizing plate that is less likely to curl and a circularly polarizing plate including the polarizing plate. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[0010] <Polarizing plate> The polarizing plate of the present invention is a polarizing plate comprising a polarizing film and a protective layer adjacent to the polarizing film, wherein the polarizing film comprises a cured product of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye and has a thickness of 0.1 to 5 μm, and the protective layer is a cured product layer of a curable composition containing a cationically polymerizable compound and has a thickness of 0.2 to 5 μm.

[0011] (polarizing film) In the polarizing plate of the present invention, the polarizing film is composed of a cured product of a polymerizable liquid crystal composition (hereinafter also referred to as a "polarizing film-forming composition") containing a polymerizable liquid crystal compound and a dichroic dye, and has a thickness of 0.1 to 5 μm. The polarizing film may be a single layer or a multilayer of two or more layers composed of the cured product of the polymerizable liquid crystal composition, or a multilayer of one or more layers composed of the cured product of the polymerizable liquid crystal composition and one or more alignment films for forming the cured product. The polarizing film may be a horizontal polarizing film (hereinafter also simply referred to as a "horizontal polarizing film") obtained by curing the polymerizable liquid crystal compound and the dichroic dye in a state where they are aligned horizontally relative to the plane of the polarizing film, or a vertical polarizing film (hereinafter also simply referred to as a "vertical polarizing film") obtained by curing the polymerizable liquid crystal compound and the dichroic dye in a state where they are aligned vertically (thickness direction) relative to the plane of the polarizing film. A horizontal polarizing film typically transmits light vibrating in the direction of its transmission axis but blocks polarized light vibrating perpendicularly to the transmission axis, thereby functioning as a polarizing film that extracts linearly polarized light from incident natural light. Furthermore, the vertical polarizing film can absorb light from an oblique direction and function as a polarizing film having an oblique optical compensation effect. The polarizing plate of the present invention may include either a horizontal polarizing film or a vertical polarizing film as a polarizing film, or may include both. When the polarizing plate includes both a horizontal polarizing film and a vertical polarizing film, the polarizing film located on the protective layer side may be either a horizontal polarizing film or a vertical polarizing film.

[0012] In a preferred embodiment of the present invention, from the viewpoint of suppressing curling, the polarizing film is preferably a single layer made of a cured product of a polymerizable liquid crystal composition, the layer made of the cured product of the polymerizable liquid crystal composition being adjacent to a protective layer, or the polarizing film is preferably made of a layer made of a cured product of a polymerizable liquid crystal composition and an alignment film for forming the layer, the layer made of the cured product of the polymerizable liquid crystal composition being adjacent to a protective layer.

[0013] The thickness of the polarizing film is 0.1 to 5 μm. The thickness of the polarizing film is the thickness of a polarizing layer made of a cured product of the polymerizable liquid crystal composition contained in the polarizing film. If the polarizing film has an alignment film, the thickness of the alignment film is not included in the thickness of the polarizing film. From the viewpoint of further thinning and suppressing curling, the thickness of the polarizing film is preferably 0.5 to 4 μm, more preferably 1 to 3.5 μm, and even more preferably 1.5 to 3 μm. The thickness of the polarizing film can be measured using a laser microscope, a film thickness meter, an ellipsometer, or the like. The same applies to the measurement of the thickness of each layer, such as a protective layer, constituting the polarizing plate and circular polarizing plate, hereinafter.

[0014] A polarizing film-forming composition for forming a polarizing film will be described. This description applies to both horizontal and vertical polarizing films unless otherwise specified. The polymerizable liquid crystal compound contained in the polarizing film-forming composition is a compound having at least one polymerizable group and liquid crystallinity. Here, the polymerizable group refers to a group that participates in a polymerization reaction, preferably a photopolymerizable group. The photopolymerizable group refers to a group that can participate in a polymerization reaction by an active radical generated from a polymerization initiator or an acid. Examples of polymerizable groups that the polymerizable liquid crystal compound has include vinyl groups, vinyloxy groups, 1-chlorovinyl groups, isopropenyl groups, 4-vinylphenyl groups, acryloyloxy groups, methacryloyloxy groups, oxiranyl groups, and oxetanyl groups. Among these, radically polymerizable groups are preferred, with acryloyloxy groups, methacryloyloxy groups, vinyloxy groups, oxiranyl groups, and oxetanyl groups being more preferred, and acryloyloxy groups and methacryloyloxy groups being even more preferred.

[0015] In the present invention, 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 a high degree of orientational order and excellent polarizing function can be formed. From the viewpoint of achieving a higher degree of orientational order, the liquid crystal state exhibited by the polymerizable liquid crystal compound is more preferably a high-order smectic phase (high-order smectic liquid crystal state). Here, the high-order smectic phase refers to a smectic B phase, a smectic D phase, a smectic E phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic I phase, a smectic J phase, a smectic K phase, and a smectic L phase. Among these, the smectic B phase, the smectic F phase, and the smectic I phase are more preferred, and the smectic B phase is even more preferred. The liquid crystal property may be either a thermotropic or lyotropic liquid crystal, but a thermotropic liquid crystal is preferred because it allows for precise film thickness control. The polymerizable liquid crystal compound may be a monomer, or may be an oligomer or polymer in which a polymerizable group is polymerized.

[0016] An example of such a polymerizable liquid crystal compound is a compound represented by formula (A) (hereinafter, also referred to as "polymerizable liquid crystal compound (A)"). U 1 -V 1 -W 1 -(X 1 -Y 1 ) n -X 2 -W 2 -V 2 -U 2 (A)

[0017] In formula (A), X 1 and X 2are each independently a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with a substituent selected from the group consisting of 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, and a nitro group, and a carbon atom constituting the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom, provided that X 1 and X 2 At least one of the groups is a 1,4-phenylene group which may have the above-mentioned substituents, or a cyclohexane-1,4-diyl group which may have the above-mentioned substituents. Y 1 is a single bond or a divalent linking group. n is 1 to 3, and when n is 2 or more, multiple X 1 may be the same or different. 2 Multiple X 1 In addition, when n is 2 or more, a plurality of Y 1 may be the same or different. From the viewpoint of liquid crystal properties, n is preferably 2 or more. U 1 represents a hydrogen atom or a polymerizable group. U 2 represents a polymerizable group. W 1 and W 2 are each independently a single bond or a divalent linking group. V 1 and V 2 are each independently an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and -CH2- constituting the alkanediyl group may be replaced by -O-, -CO-, -S- or -NH-.

[0018] In the polymerizable liquid crystal compound (A), X 1 and X 2are each independently preferably an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group, and X 1 and X 2 At least one of these is an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group, preferably a trans-cyclohexane-1,4-diyl group. The optionally substituted 1,4-phenylene group or the optionally substituted cyclohexane-1,4-diyl group may optionally have a substituent, such as an alkyl group having 1 to 4 carbon atoms, a cyano group, or a halogen atom, such as a chlorine atom or a fluorine atom. Preferably, the group is unsubstituted.

[0019] The polymerizable liquid crystal compound (A) is a compound represented by the formula (A1): -(X 1 -Y 1 ) n -X 2 - (A1) [In the formula, X 1 , Y 1 , X 2 and n have the same meanings as above.] (hereinafter referred to as "partial structure (A1)") preferably has an asymmetric structure from the viewpoint of the development of smectic liquid crystal properties. Examples of the polymerizable liquid crystal compound (A) in which the partial structure (A1) has an asymmetric structure include: n is 1 and one X 1 and X 2 and (B) are different from each other in structure. n is 2 and two Y 1 are compounds having the same structure as each other, and two X 1 have the same structure as each other, and one X 2 These two X 1 a polymerizable liquid crystal compound (A) having a structure different from that of Two Xs 1 Of the W 1 X binds to1 But the other X 1 and X 2 The other X 1 and X 2 The polymerizable liquid crystal compound (A) may also be a compound having the same structure as the compound (A). n is 3 and there are three Y 1 are compounds having the same structure as each other, and three X 1 and one X 2 The polymerizable liquid crystal compound (A) may have a structure in which any one of the following three is different from all of the other three:

[0020] Y 1 -CH2CH2-, -CH2O-, -CH2CH2O-, -COO-, -OCOO-, single bond, -N=N-, -CR a =CR b -, -C≡C-, -CR a =N- or -CO-NR a - is preferred. a and R b are each independently a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 1 is more preferably -CH2CH2-, -COO- or a single bond, and 1 If there is an X 2 Y bonded with 1 is more preferably -CH2CH2- or -CH2O-. 1 and X 2 When all of Y are the same structure, two or more Y 1 It is preferable that there are plural Y 1 When the compound has an asymmetric structure, the compound tends to exhibit smectic liquid crystallinity.

[0021] U 2 is a polymerizable group. 1 is a hydrogen atom or a polymerizable group, preferably a polymerizable group. 1 and U 2Preferably, both of U are polymerizable groups, and preferably both are radically polymerizable groups. Examples of the polymerizable group include the same groups as those exemplified above as the polymerizable group contained in the polymerizable liquid crystal compound (A). 1 and a polymerizable group represented by U 2 The polymerizable groups represented by may be different from each other, but are preferably the same type of group. The polymerizable groups may be in a polymerized state or an unpolymerized state, but are preferably in an unpolymerized state.

[0022] V 1 and V 2 Examples of the alkanediyl group represented by the formula (V) include a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a decane-1,10-diyl group, a tetradecane-1,14-diyl group, and an icosane-1,20-diyl group. 1 and V 2 is preferably an alkanediyl group having 2 to 12 carbon atoms, and more preferably an alkanediyl group having 6 to 12 carbon atoms.

[0023] Examples of the substituent that the alkanediyl group may optionally have include a cyano group and a halogen atom, but the alkanediyl group is preferably unsubstituted, and more preferably an unsubstituted linear alkanediyl group.

[0024] W 1 and W 2 are each independently preferably a single bond, -O-, -S-, -COO- or -OCOO-, more preferably a single bond or -O-.

[0025] As a structure that readily exhibits smectic liquid crystallinity, it is preferable for the polymerizable liquid crystal compound to have an asymmetric molecular structure. Specifically, polymerizable liquid crystal compounds having structures represented by the following formulae (Aa) to (Ai) readily exhibit smectic liquid crystallinity and are suitable as the polymerizable liquid crystal compound (A). Furthermore, from the viewpoint of readily exhibiting higher-order smectic liquid crystallinity, it is more preferable for the polymerizable liquid crystal compound to have a structure represented by formula (Aa), formula (Ab), or formula (Ac). In the following formulae (Aa) to (Ai), * represents a bond (single bond).

[0026] [ka]

[0027] Specific examples of the polymerizable liquid crystal compound (A) include compounds represented by formulae (A-1) to (A-25). When the polymerizable liquid crystal compound (A) has a cyclohexane-1,4-diyl group, the cyclohexane-1,4-diyl group is preferably a trans isomer.

[0028] [ka]

[0029] [ka]

[0030] [ka]

[0031] Among these, at least one selected from the group consisting of compounds represented by formula (A-2), formula (A-3), formula (A-4), formula (A-5), formula (A-6), formula (A-7), formula (A-8), formula (A-13), formula (A-14), formula (A-15), formula (A-16), and formula (A-17) is preferred. As the polymerizable liquid crystal compound (A), one compound may be used alone, or two or more compounds may be used in combination.

[0032] The polymerizable liquid crystal compound (A) can be produced by a known method such as that described in Lub et al., Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996) or Japanese Patent No. 4719156.

[0033] The composition for forming a polarizing film may contain a polymerizable liquid crystal compound other than the polymerizable liquid crystal compound (A) as long as the effects of the present invention are not impaired. From the viewpoint of obtaining a polarizing film with a high degree of orientational order, the proportion of the polymerizable liquid crystal compound (A) to the total mass of all polymerizable 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, and all (100% by mass) may be the polymerizable liquid crystal compound (A).

[0034] When the composition for forming a polarizing film contains two or more polymerizable liquid crystal compounds, it is preferable that at least one of them is the polymerizable liquid crystal compound (A), and all of the compounds contained in the composition for forming a polarizing film may be the polymerizable liquid crystal compound (A).

[0035] The content of the polymerizable liquid crystal compound in the composition for forming a polarizing film 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, based on the solid content of the composition for forming a polarizing film. When the content of the polymerizable liquid crystal compound is within the above range, the orientation of the polymerizable liquid crystal compound tends to be high. In this specification, the solid content refers to the total amount of components excluding the solvent from the composition for forming a polarizing film. Hereinafter, when the solid content is referred to in this specification, it similarly refers to the components excluding volatile components such as the solvent from the target composition.

[0036] The polarizing film-forming composition further contains a dichroic dye. Here, the dichroic dye refers to a dye having different absorbance in the long axis direction and the short axis direction of the molecule. The dichroic dye is not particularly limited as long as it has the above-mentioned properties, and may be a dye or a pigment. Two or more dyes or pigments may be used in combination, or a dye and a pigment may be used in combination. The dichroic dyes may be used alone or in combination. However, to achieve absorption across the entire visible light range, it is preferable to combine two or more dichroic dyes, and more preferably to combine three or more dichroic dyes. In particular, mixing two or more dichroic dyes with different absorption wavelengths allows the production of polarizing films of various hues and polarizing films that absorb across the entire visible light range.

[0037] The dichroic dye preferably has the property of absorbing visible light, and has a maximum absorption wavelength (λ ) in the range of 300 to 700 nm. MAX ) is preferred. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes. Of these, azo dyes are preferred.

[0038] Examples of azo dyes include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbene azo dyes, and bisazo dyes and trisazo dyes are preferred, such as a compound represented by formula (I) (hereinafter also referred to as "compound (I)").

[0039] K 1 (-N=NK 2 ) p -N=NK 3 (I) [In formula (I), K 1 and K. 3 represent, independently of each other, a phenyl group which may have a substituent, a naphthyl group which may have a substituent, a phenyl benzoate group which may have a substituent, or a monovalent heterocyclic group which may have a substituent. 2represents a p-phenylene group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent, a 4,4'-stilbenylene group which may have a substituent, or a divalent heterocyclic group which may have a substituent. p represents an integer of 0 to 4. When p is an integer of 2 or more, a plurality of K 2 may be the same or different. The -N=N- bond may be replaced with a -C=C-, -COO-, -NHCO-, or -N=CH- bond as long as the compound exhibits absorption in the visible region.

[0040] Examples of monovalent heterocyclic groups include groups in which one hydrogen atom has been removed from a heterocyclic compound such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, benzoxazole, etc. Examples of divalent heterocyclic groups include groups in which two hydrogen atoms have been removed from the above heterocyclic compounds.

[0041] K 1 and K. 3 Phenyl group, naphthyl group, benzoic acid phenyl ester group and monovalent heterocyclic group in 2 In the formula (I), the p-phenylene group, the naphthalene-1,4-diyl group, the 4,4'-stilbenylene group, and the divalent heterocyclic group may optionally have a substituent, such as an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms and having a polymerizable group, or an alkenyl group having 1 to 4 carbon atoms; an alkoxy group having 1 to 20 carbon atoms, such as a methoxy group, an ethoxy group, or a butoxy group; an alkoxy group having 1 to 20 carbon atoms and having a polymerizable group; a fluorinated alkyl group having 1 to 4 carbon atoms, such as a trifluoromethyl group; Examples of the polymerizable group include an ano group, a nitro group, a halogen atom, and substituted or unsubstituted amino groups such as an amino group, a diethylamino group, and a pyrrolidino group (a substituted amino group refers to an amino group having one or two alkyl groups of 1 to 6 carbon atoms, an amino group having one or two alkyl groups of 1 to 6 carbon atoms and a polymerizable group, or an amino group in which two substituted alkyl groups are bonded to form an alkanediyl group of 2 to 8 carbon atoms. An unsubstituted amino group is -NH2). Examples of the polymerizable group include a (meth)acryloyl group and a (meth)acryloyloxy group.

[0042] Among the compounds (I), compounds represented by any one of the following formulae (I-1) to (I-8) are preferred. [ka] [In formulas (I-1) to (I-8), B 1 ~B 30 are each independently 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 a substituted amino group and an unsubstituted amino group are as defined above), a chlorine atom, or a trifluoromethyl group. n1 to n4 each independently represent an integer of 0 to 3. If n1 is 2 or more, multiple B 2 may be the same or different from each other, If n2 is 2 or more, multiple B 6 may be the same or different from each other, If n3 is 2 or more, multiple B 9 may be the same or different from each other, If n4 is 2 or more, multiple B 14 may be the same or different.]

[0043] The anthraquinone dye is preferably a compound represented by formula (I-9). [ka] [In formula (I-9), R 1 ~R 8 are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.]

[0044] The oxazone dye is preferably a compound represented by formula (I-10). [ka] [In formula (I-10), R 9 ~R 15 are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.]

[0045] The acridine dye is preferably a compound represented by formula (I-11). [ka] [In formula (I-11), R 16 ~R 23 are, independently of each other, a hydrogen atom, -R x , -NH2, -NHR x , -NR x 2, -SR x or a halogen atom. R x represents an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 12 carbon atoms.] In formula (I-9), formula (I-10) and formula (I-11), R x Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group, and examples of the aryl group having 6 to 12 carbon atoms include a phenyl group, a toluyl group, a xylyl group, and a naphthyl group.

[0046] As the cyanine dye, compounds represented by formula (I-12) and compounds represented by formula (I-13) are preferred. [ka] [In formula (I-12), D 1 and D 2 represent, independently of each other, a group represented by any one of formulae (I-12a) to (I-12d). [ka] n5 represents an integer from 1 to 3. [ka] [In formula (I-13), D 3 and D 4 each independently represents a group represented by any one of formulas (1-13a) to (1-13h). [ka] n6 represents an integer from 1 to 3.

[0047] The weight-average molecular weight of the dichroic dye is usually 300 to 2,000, and preferably 400 to 1,000.

[0048] The content of the dichroic dye in the composition for forming a polarizing film can be appropriately determined depending on the type of dichroic dye used, but is preferably 1 to 60 mass %, more preferably 1 to 20 mass %, and even more preferably 1 to 15 mass %, based on the solid content of the composition for forming a polarizing film. When the content of the dichroic dye is within the above range, the orientation of the polymerizable liquid crystal compound is unlikely to be disturbed, and a polarizing film having a high degree of orientational order can be obtained.

[0049] The polarizing film-forming composition may contain a polymerization initiator. The polymerization initiator is a compound capable of initiating a polymerization reaction of a polymerizable liquid crystal compound or the like. As the polymerization initiator, a photopolymerization initiator that generates an active radical or an acid by the action of light is preferred, since it can initiate a polymerization reaction under lower temperature conditions, and a photopolymerization initiator that generates a radical by the action of light is more preferred. The polymerization initiators may be used alone or in combination of two or more.

[0050] As the photopolymerization initiator, known photopolymerization initiators can be used. For example, photopolymerization initiators that generate active radicals include self-cleavage type photopolymerization initiators and hydrogen abstraction type photopolymerization initiators. Examples of the self-cleaving photopolymerization initiator that can be used include self-cleaving benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, and azo compounds. Examples of the hydrogen abstraction photopolymerization initiator that can be used include hydrogen abstraction benzophenone compounds, benzoin ether compounds, benzil ketal compounds, dibenzosuberone compounds, anthraquinone compounds, xanthone compounds, thioxanthone compounds, halogenoacetophenone compounds, dialkoxyacetophenone compounds, halogenobisimidazole compounds, halogenotriazine compounds, and triazine compounds.

[0051] As the photopolymerization initiator that generates an acid, an iodonium salt, a sulfonium salt, or the like can be used.

[0052] Among these, a reaction at low temperature is preferred from the viewpoint of preventing dissolution of the dye, and a self-cleaving photopolymerization initiator is preferred from the viewpoint of reaction efficiency at low temperature, and an acetophenone-based compound, a hydroxyacetophenone-based compound, an α-aminoacetophenone-based compound, or an oxime ester-based compound is particularly preferred.

[0053] Specific examples of the photopolymerization initiator include the following: benzoin compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether and benzoin isobutyl ether; hydroxyacetophenone compounds such as 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethan-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexyl phenyl ketone, and oligomers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one; α-aminoacetophenone compounds such as 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one and 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one; Oxime ester compounds such as 1,2-octanedione, 1-[4-(phenylthio)-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime); acylphosphine oxide compounds such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; benzophenone compounds such as benzophenone, methyl o-benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, and 2,4,6-trimethylbenzophenone; Dialkoxyacetophenone compounds such as diethoxyacetophenone; 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)ethenyl]-1,3,5-triazine Triazine compounds such as riazine, 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine, and 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine. The photopolymerization initiator may be appropriately selected, for example, in relation to the polymerizable liquid crystal compound that forms the polarizing film from the photopolymerization initiator.

[0054] Alternatively, commercially available photopolymerization initiators may be used. Examples of commercially available polymerization initiators include Irgacure (registered trademark) 907, 184, 651, 819, 250, 369, 379, 127, 754, OXE01, OXE02, and OXE03 (manufactured by BASF); Omnirad BCIM, Esacure 1001M, and Esacure KIP160 (manufactured by IDM Resins). BV); Seikuol (registered trademark) BZ, Z, and BEE (Seiko Chemical Co., Ltd.); Kayacure (registered trademark) BP100 and UVI-6992 (Dow Chemical Co., Ltd.); Adeka Optomer SP-152, N-1717, N-1919, SP-170, Adeka Arcles NCI-831, Adeka Arcles NCI-930 (ADEKA Corporation); TAZ-A and TAZ-PP (Nihon SiberHegner Co., Ltd.); and TAZ-104 (Sanwa Chemical Co., Ltd.).

[0055] The content of the polymerization initiator is preferably 0.1 to 20 parts by mass, 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, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the polymerization initiator is within the above range, the polymerization reaction can be carried out without significantly disturbing the alignment of the polymerizable liquid crystal compound.

[0056] The polarizing film-forming composition may contain a leveling agent. The leveling agent adjusts the fluidity of the polarizing film-forming composition and functions to make the coating film obtained by applying the composition flatter. Specific examples include surfactants. The leveling agent is preferably at least one selected from the group consisting of leveling agents containing a polyacrylate compound as a main component and leveling agents containing a fluorine atom-containing compound as a main component. The leveling agents can be used alone or in combination of two or more.

[0057] Examples of leveling agents containing polyacrylate compounds as their main components include BYK-350, BYK-352, BYK-353, BYK-354, BYK-355, BYK-358N, BYK-361N, BYK-380, BYK-381, and BYK-392 (BYK Chemie).

[0058] Examples of leveling agents containing a fluorine atom-containing compound as a main component include Megafac (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, E5844 (Daikin Fine Chemical Research Institute, Inc.); F-top EF301, F-top EF303, F-top EF351, and F-top EF352 (Mitsubishi Materials Electronic Chemicals Co., Ltd.).

[0059] When the composition for forming a polarizing film contains a leveling agent, the content thereof is preferably 0.01 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, relative to 100 parts by mass of the polymerizable liquid crystal compound. When the content of the leveling agent is within the above range, the polymerizable liquid crystal compound is easily aligned, unevenness is less likely to occur, and a smoother polarizing film tends to be obtained.

[0060] The polarizing film-forming composition may contain additives other than the leveling agent. Examples of the additives include a polymerizable non-liquid crystal compound, a photosensitizer, an antioxidant, a release agent, a stabilizer, a colorant such as a bluing agent, a flame retardant, and a lubricant. When the polarizing film-forming composition contains other additives, the content of the additives is preferably more than 0% and not more than 20% by mass, more preferably more than 0% and not more than 10% by mass, based on the solid content of the polarizing film-forming composition.

[0061] The composition for forming a polarizing film can be produced by a conventionally known method for preparing a liquid crystal composition, and can usually be prepared by mixing and stirring a polymerizable liquid crystal compound and a dichroic dye, and, if necessary, a polymerization initiator and the above-mentioned additives, etc. Furthermore, since liquid crystal compounds exhibiting smectic liquid crystallinity generally have high viscosity, the viscosity may be adjusted by adding a solvent to the composition from the viewpoint of improving the coatability of the liquid crystal composition and facilitating the formation of a polarizing film.

[0062] The solvent may be appropriately selected depending on the solubility of the polymerizable liquid crystal compound and dichroic dye used, and is preferably a solvent that can completely dissolve the above components and is inactive to the polymerization reaction.

[0063] Specific examples of the solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, 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; and acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, 2-heptanone, and methyl isobutyl ketone. Examples of suitable solvents include ketone solvents, 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 may be used alone or in combination of two or more.

[0064] The content of the solvent is preferably 100 to 1900 parts by mass, more preferably 150 to 1000 parts by mass, and even more preferably 180 to 800 parts by mass, based on 100 parts by mass of the solid content of the composition for forming a polarizing film.

[0065] In the present invention, the cured product layer formed from the polarizing film-forming composition is preferably a liquid crystal cured film with a high degree of orientational order. A liquid crystal cured film with a high degree of orientational order exhibits a Bragg peak derived from a higher-order structure such as a hexatic phase or a crystalline phase in X-ray diffraction measurement. A Bragg peak refers to a peak derived from the planar periodic structure of molecular orientation. Therefore, the polarizing film (cured product layer) constituting the polarizing plate of the present invention preferably exhibits a Bragg peak in X-ray diffraction measurement. That is, in the polarizing film (cured product layer) of the present invention, the polymerizable liquid crystal compound or its polymer is preferably oriented so that the film exhibits a Bragg peak in X-ray diffraction measurement. In one embodiment of the present invention, the planar periodic spacing of the molecular orientation is preferably 3.0 to 6.0 Å. A high degree of orientational order that exhibits a Bragg peak can be achieved by controlling the type of polymerizable liquid crystal compound used, the type and amount of dichroic dye, and the type and amount of polymerization initiator.

[0066] In the present invention, the polarizing film may include an alignment film. The alignment film has an alignment-regulating force that aligns the polymerizable liquid crystal compound in a desired direction, and a precisely aligned polarizing film (cured product layer) can be easily obtained by applying a polarizing film-forming composition onto the alignment film. The alignment film preferably has solvent resistance that prevents the polarizing film-forming composition from dissolving when applied, and also has heat resistance during heat treatment for removing the solvent or orienting the polymerizable liquid crystal compound. Furthermore, it is preferable that the difference in refractive index between the alignment film and the polarizing film or the protective film is small.

[0067] Examples of the alignment film include an alignment film containing an orientable polymer, a photo-alignment film, a groove alignment film having a concave-convex pattern or a plurality of grooves on the surface, a stretched film stretched in the alignment direction, etc. These various alignment films can be appropriately selected from those conventionally known in the art according to the desired alignment control force.

[0068] In one embodiment of the present invention, a photo-alignment film is preferred from the viewpoint of improving alignment accuracy and adhesion to a cured product layer formed from a polarizing film-forming composition, etc. The photo-alignment film is also advantageous in that the direction of the alignment regulating force can be arbitrarily controlled by selecting the polarization direction of the polarized light to be irradiated.

[0069] A photo-alignment film is usually obtained by applying a composition containing a polymer, oligomer, or monomer having a photoreactive group and a solvent (hereinafter also referred to as a "photo-alignment film-forming composition") to a substrate or the like, and irradiating the substrate with polarized light (preferably polarized UV). When the polymer or the like contained in the photo-alignment film-forming composition has the same reactive group (e.g., a (meth)acryloyl group) as the functional group contained in the polymerizable group of the polymerizable liquid crystal compound that forms the polarizing film, the adhesion between the cured layer of the polymerizable liquid crystal compound and the alignment film tends to be improved.

[0070] The photoreactive group refers to a group that exhibits liquid crystal alignment ability upon irradiation with light. Specific examples include groups involved in photoreactions that induce molecular alignment upon irradiation with light or that are the origin of liquid crystal alignment ability, such as isomerization, dimerization, photocrosslinking, or photodecomposition. Among these, groups involved in dimerization or photocrosslinking are preferred because of their excellent alignment properties. As the photoreactive group, groups having an unsaturated bond, particularly a double bond, are preferred, and groups having at least one bond selected from the group consisting of a carbon-carbon double bond (C=C bond), a carbon-nitrogen double bond (C=N bond), a nitrogen-nitrogen double bond (N=N bond), and a carbon-oxygen double bond (C=O bond) are particularly preferred.

[0071] Specifically, such an alignment film may be a photo-alignment film such as those described in JP-A-2020-56834, JP-A-2021-196514, etc.

[0072] The thickness of the alignment film is preferably 10 to 3,000 nm, more preferably 10 to 1,000 nm, even more preferably 10 to 500 nm, still more preferably 10 to 300 nm, and particularly preferably 30 to 300 nm. When the thickness of the alignment film is within the above range, good adhesion is exhibited at the interface with a cured product layer formed from the polarizing film-forming composition on the alignment film, while an alignment regularity can be exerted, allowing a polarizing film to be formed with high alignment order. The thickness of the alignment film can be measured using an ellipsometer.

[0073] The polarizing film can be produced by, for example, forming a coating film of a polarizing film-forming composition; removing the solvent from the coating; raising the temperature to a temperature at which the polymerizable liquid crystal compound undergoes a phase transition to a liquid phase or higher, and then lowering the temperature to cause the polymerizable liquid crystal compound to undergo a phase transition to a liquid crystal phase (e.g., a smectic liquid crystal phase); and polymerizing the polymerizable liquid crystal compound while maintaining the liquid crystal phase; It can be produced by a method comprising:

[0074] The coating film of the composition for forming a polarizing film can be formed, for example, by applying the composition for forming a polarizing film onto a substrate, an alignment film, etc. The substrate can be a layer constituting the polarizing plate of the present invention, but in one embodiment of the present invention, it is preferably one that is finally peeled off.

[0075] As the substrate, a resin film substrate conventionally known in the field of optical films can be used. Specific examples of resins constituting such resin films include polyolefin resins such as polyethylene and polypropylene; cycloolefin resins such as norbornene-based polymers; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; poly(meth)acrylic acid resins such as (meth)acrylic acid and polymethyl(meth)acrylate; 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; polyarylate resins; polysulfone resins; polyethersulfone resins; polyamide resins; polyimide resins; polyether ketone resins; polyphenylene sulfide resins; polyphenylene oxide resins, and mixtures thereof. These resins may be used alone or in combination of two or more. These resins can be formed into a film by known means such as solvent casting or melt extrusion to form a resin film substrate. Commercially available products may also be used as the film substrate or the resin constituting the film substrate. The film substrate may be subjected to a surface treatment such as corona treatment or plasma treatment, and may also be subjected to a release treatment in the case where the substrate is to be peeled off later. The thickness of the substrate is not particularly limited and may be appropriately selected within a practical range, for example, about 5 μm to 300 μm.

[0076] The method for applying the polarizing film-forming composition is not particularly limited, and any known method can be used, such as a coating method such as spin coating, extrusion, gravure coating, die coating, bar coating, or applicator method, or a printing method such as a flexographic method.

[0077] When the polarizing film-forming composition contains a solvent, the solvent is usually removed from the coated composition. Examples of methods for removing the solvent include natural drying, forced air drying, heat drying, and vacuum drying. The dried film is preferably dried so that the residual solvent in the polarizing film is 1% by weight or less of the total mass of the polarizing film. The amount of residual solvent can be determined by peeling the polarizing film from the substrate, weighing it, immersing the polarizing film in a solvent that dissolves polarizing films, such as tetrahydrofuran, and irradiating it with ultrasound for about 10 minutes to extract the dissolved components, followed by analyzing the solution by gas chromatography. The drying conditions, such as the drying temperature and drying time, can be appropriately determined depending on the composition of the polarizing film-forming composition, the materials of the substrate and alignment film, and other factors.

[0078] The polymerizable liquid crystal compound in the coating film is usually heated to a temperature at which it transitions to a liquid crystal state or a solution state or higher, and then cooled to a temperature at which the liquid crystal aligns, whereby the compound aligns together with the dichroic dye to form a liquid crystal phase.

[0079] The temperature at which the polymerizable liquid crystal compound in the coating film is oriented can be determined in advance by observing the texture of a composition containing the polymerizable liquid crystal compound. Alternatively, the solvent removal and liquid crystal orientation may be performed simultaneously. The temperature at this time varies depending on the type of solvent to be removed and the type of polymerizable liquid crystal compound used, but is preferably in the range of 50 to 200°C, more preferably 80 to 130°C.

[0080] A polarizing film is formed as a cured layer of the liquid crystal composition by polymerizing and curing the polymerizable liquid crystal compound while maintaining its liquid crystal state. Photopolymerization is a preferred polymerization method. In photopolymerization, the light irradiated onto the dried film is appropriately selected depending on the type of polymerizable liquid crystal compound contained in the dried film (particularly the type of polymerizable group possessed by the polymerizable liquid crystal compound), the type and amount of polymerization initiator, etc. A cured layer containing a polymerizable liquid crystal compound polymerized while maintaining a smectic liquid crystal phase has higher polarization performance than conventional host-guest type liquid crystal cured layer, i.e., a liquid crystal cured layer obtained by polymerizing a polymerizable liquid crystal compound while maintaining a nematic liquid crystal phase, and also has superior polarization performance and film strength compared to layers coated with only a dichroic dye or lyotropic liquid crystal.

[0081] (protective layer) The polarizing plate of the present invention includes a protective layer adjacent to the polarizing film. The protective layer is a cured product layer of a curable composition containing a cationically polymerizable compound and has a thickness of 0.2 to 5 μm. The polarizing plate of the present invention has a protective layer of a cured product layer of a curable composition containing a cationically polymerizable compound adjacent to the polarizing film. This protective layer can suppress the diffusion of the dichroic dye in a polarizing film formed using a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye, and can suppress curling of the polarizing plate even though the polarizing film includes a thin polarizing film and a protective layer. Polarizing films using dichroic dyes may have protective layers to prevent the diffusion of the dichroic dye. However, protective layers using conventional radically polymerizable compounds, for example, can cause severe curling, especially in thin polarizing films. The present inventors have found that such severe curling is likely to occur when a radically polymerizable compound that is prone to cure shrinkage is used or when lamination is performed by heating, for example. They have also found that providing a protective layer that is a cured product layer of a curable composition containing a cationically polymerizable compound can suppress curling while sufficiently suppressing the diffusion of the dichroic dye.

[0082] The protective layer, which is a cured layer of the curable composition containing a cationically polymerizable compound, has a thickness of 0.2 to 5 μm. If the protective layer is less than 0.2 μm, the diffusion suppression ability is insufficient, and if it exceeds 5 μm, curing may be insufficient. From the viewpoint of further thinning and suppressing curling, the thickness of the protective layer is preferably 0.5 to 4 μm, more preferably 0.7 to 3 μm, and even more preferably 1 to 2.5 μm.

[0083] A curable composition containing a cationically polymerizable compound for forming a protective layer (hereinafter also referred to as a "protective layer-forming composition") will be described. The cationically polymerizable compound contained in the protective layer-forming composition refers to a compound or oligomer that undergoes a cationic polymerization reaction and hardens when exposed to active energy rays such as ultraviolet light, visible light, electron beams, or X-rays or when heated, and examples of such compounds include epoxy compounds, oxetane compounds, and vinyl compounds. Among these, the cationically polymerizable compound is preferably a polymerizable compound having a cyclic ether structure, and more preferably a polymerizable compound having an epoxy group and / or an oxetanyl group.

[0084] A polymerizable compound having an epoxy group (also referred to as an "epoxy compound") is a compound having one or more, preferably two or more, epoxy groups in the molecule. The epoxy compound may be used alone or in combination of two or more. Examples of the epoxy compound include alicyclic epoxy compounds, aromatic epoxy compounds, hydrogenated epoxy compounds, and aliphatic epoxy compounds. Among these, from the viewpoints of suppressing curling, weather resistance, and reducing the curing rate, it is preferable that the epoxy compound contains an alicyclic epoxy compound and / or an aliphatic epoxy compound.

[0085] Alicyclic epoxy compounds are compounds having one or more epoxy groups bonded to an alicyclic ring in the molecule, such as alicyclic epoxy compounds having an epoxycyclopentane structure or an epoxycyclohexane structure. Specific examples include 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate, ethylene bis(3,4-epoxycyclohexanecarboxylate), bis(3,4-epoxycyclohexylmethyl)adipate, bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, diethylene glycol bis(3,4-epoxycyclohexylmethyl) ether), ethylene glycol bis(3,4-epoxycyclohexyl methyl ether), 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro[5.2.2.5.2.2]heneicosane, 3-(3,4-epoxycyclohexyl)-8,9-epoxy-1,5-dioxaspiro[5.5]undecane, 4-vinylcyclohexene dioxide, limonene dioxide, bis(2,3-epoxycyclopentyl)ether, dicyclopentadiene dioxide, etc.

[0086] Aromatic epoxy compounds are compounds having an aromatic ring and an epoxy group in the molecule. Specific examples include bisphenol-type epoxy compounds or oligomers thereof, such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; novolac-type epoxy resins, such as phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; polyfunctional epoxy compounds, such as glycidyl ether of 2,2',4,4'-tetrahydroxydiphenylmethane and glycidyl ether of 2,2',4,4'-tetrahydroxybenzophenone; and polyfunctional epoxy resins, such as epoxidized polyvinylphenol.

[0087] The hydrogenated epoxy compound is a glycidyl ether of a polyol having an alicyclic ring, and may be a glycidyl ether of a nuclear-hydrogenated polyhydroxy compound obtained by selectively hydrogenating the aromatic ring of an aromatic polyol in the presence of a catalyst under pressure. Specific examples of aromatic polyols include bisphenol-type compounds such as bisphenol A, bisphenol F, and bisphenol S; novolac-type resins such as phenol novolac resin, cresol novolac resin, and hydroxybenzaldehyde phenol novolac resin; and polyfunctional compounds such as tetrahydroxydiphenylmethane, tetrahydroxybenzophenone, and polyvinylphenol. A glycidyl ether can be obtained by reacting epichlorohydrin with an alicyclic polyol obtained by hydrogenating the aromatic ring of an aromatic polyol, for example, a diglycidyl ether of hydrogenated bisphenol A.

[0088] Aliphatic epoxy compounds are compounds that have at least one oxirane ring (three-membered cyclic ether) bonded to an aliphatic carbon atom in the molecule. Examples include monofunctional epoxy compounds such as butyl glycidyl ether and 2-ethylhexyl glycidyl ether; bifunctional epoxy compounds such as 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and neopentyl glycol diglycidyl ether; trifunctional or higher epoxy compounds such as trimethylolpropane triglycidyl ether and pentaerythritol tetraglycidyl ether; and epoxy compounds that have one epoxy group directly bonded to an alicyclic ring and an oxirane ring bonded to an aliphatic carbon atom, such as 4-vinylcyclohexene dioxide and limonene dioxide. Among these, bifunctional epoxy compounds (also known as aliphatic diepoxy compounds) that have two oxirane rings bonded to an aliphatic carbon atom in the molecule are preferred.

[0089] Polymerizable compounds having an oxetanyl group (also referred to as "oxetane compounds") are compounds containing one or more oxetane rings (oxetanyl groups) in the molecule. Specific examples include 3-ethyl-3-hydroxymethyloxetane (also known as oxetane alcohol), 2-ethylhexyloxetane, 1,4-bis[{(3-ethyloxetan-3-yl)methoxy}methyl]benzene (also known as xylylene bisoxetane), 3-ethyl-3[{(3-ethyloxetan-3-yl)methoxy}methyl]oxetane, 3-ethyl-3-(phenoxymethyl)oxetane, and 3-(cyclohexyloxy)methyl-3-ethyloxetane. The oxetane compound may be used as the main component of a cationic polymerizable compound or in combination with an epoxy compound. The use of an oxetane compound in combination can improve the curing speed of the protective layer and suppress dye diffusion.

[0090] Examples of vinyl compounds that can be cationic polymerizable compounds include aliphatic or alicyclic vinyl ether compounds. Specific examples thereof include vinyl ethers of alkyl or alkenyl alcohols having 5 to 20 carbon atoms, such as n-amyl vinyl ether, i-amyl vinyl ether, n-hexyl vinyl ether, n-octyl vinyl ether, 2-ethylhexyl vinyl ether, n-dodecyl vinyl ether, stearyl vinyl ether, and oleyl vinyl ether; hydroxyl group-containing vinyl ethers, such as 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, and 4-hydroxybutyl vinyl ether; vinyl ethers of monoalcohols having an aliphatic or aromatic ring, such as cyclohexyl vinyl ether, 2-methylcyclohexyl vinyl ether, cyclohexylmethyl vinyl ether, and benzyl vinyl ether; glycerol monovinyl ether, 1,4-butanediol monovinyl ether, 1,4-butanediol divinyl ether, and 1,6-hexanediol divinyl ether. Examples of vinyl compounds include mono- and polyvinyl ethers of polyhydric alcohols such as 1,4-dihydroxycyclohexane monovinyl ether, 1,4-dihydroxycyclohexane divinyl ether, 1,4-dihydroxymethylcyclohexane monovinyl ether, and 1,4-dihydroxymethylcyclohexane divinyl ether; polyalkylene glycol mono- and divinyl ethers such as diethylene glycol divinyl ether, triethylene glycol divinyl ether, and diethylene glycol monobutyl monovinyl ether; and other vinyl ethers such as glycidyl vinyl ether and ethylene glycol vinyl ether methacrylate. Vinyl compounds may be used as the main component of the cationically polymerizable compound, or may be used in combination with an epoxy compound, or an epoxy compound and an oxetane compound. The use of vinyl compounds in combination can improve the curing speed and reduce the viscosity of the protective layer.

[0091] In addition to the above-mentioned polymerizable compounds, the composition for forming a protective layer may further contain other cationically polymerizable compounds other than those mentioned above, such as a cyclic lactone compound, a cyclic acetal compound, a cyclic thioether compound, or a spiroorthoester compound.

[0092] In one embodiment of the present invention, the composition for forming a protective layer preferably contains an epoxy compound and / or an oxetane compound as a cationically polymerizable compound from the viewpoint of suppressing curling. In this case, the content of the epoxy compound and / or the oxetane compound (the total content when two or more types are contained) is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, relative to 100% by mass of the total amount of the cationically polymerizable compounds.

[0093] In a preferred embodiment of the present invention, the protective layer-forming composition preferably contains an oxetane compound as a cationically polymerizable compound from the viewpoints of suppressing curling and suppressing diffusion of the dichroic dye. In this case, the content of the oxetane compounds (the total content when two or more types are contained) is preferably 10% by mass or more, more preferably 30% by mass or more, even more preferably 40% by mass or more, even more preferably 50% by mass or more, and particularly preferably 60% by mass or more, relative to 100% by mass of the total amount of the cationically polymerizable compounds. For example, it may be 70% by mass or more, 80% by mass or more, or even 100% by mass.

[0094] The content of the cationic polymerizable compound contained in the composition for forming a protective layer is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, even more preferably 80% by mass or more, and particularly preferably 90% by mass or more, based on the solid content of the composition for forming a protective layer.

[0095] The content of aromatic cationically polymerizable compounds, such as aromatic epoxy compounds and / or aromatic oxetane compounds, in the protective layer-forming composition is preferably 50% by mass or less, more preferably 40% by mass or less, even more preferably 30% by mass or less, even more preferably 20% by mass or less, and particularly preferably 10% by mass or less, relative to 100% by mass of the total amount of cationically polymerizable compounds contained in the protective layer-forming composition, from the viewpoint of suppressing diffusion of dichroic dyes in the resulting polarizing plate and circular polarizing plate.

[0096] The protective layer-forming composition preferably further contains a cationic photopolymerization initiator. The cationic photopolymerization initiator generates cationic species or Lewis acids upon irradiation with active energy rays such as visible light, ultraviolet light, X-rays, or electron beams, thereby initiating the polymerization reaction of the cationic curable compound. Because the cationic photopolymerization initiator acts catalytically under light, it exhibits excellent storage stability and workability even when mixed with the cationic photocurable compound. Examples of compounds that generate cationic species or Lewis acids upon irradiation with active energy rays include onium salts such as aromatic iodonium salts and aromatic sulfonium salts, aromatic diazonium salts, and iron-arene complexes.

[0097] The aromatic iodonium salt is a compound having a diaryliodonium cation, typically a diphenyliodonium cation. The aromatic sulfonium salt is a compound having a triarylsulfonium cation, typically a triphenylsulfonium cation or a 4,4'-bis(diphenylsulfonio)diphenylsulfide cation. The aromatic diazonium salt is a compound having a diazonium cation, typically a benzenediazonium cation. The iron-arene complex is typically a cyclopentadienyliron(II) arene cation complex salt.

[0098] The cations shown above are paired with anions (negative ions) to form cationic photopolymerization initiators. Examples of anions that form cationic photopolymerization initiators include special phosphorus anions [(Rf) n PF 6-n ] - , hexafluorophosphate anion PF6 - , hexafluoroantimonate anion SbF6 - , pentafluorohydroxyantimonate anion SbF5(OH) - , hexafluoroarsenate anion AsF6 - , tetrafluoroborate anion BF4 - , tetrakis(pentafluorophenyl)borate anion B(C6F5)4 - Among them, from the viewpoint of the curability of cationic polymerizable compounds and the safety of the resulting protective layer, special phosphorus-based anions [(Rf) n PF 6-n ] - , hexafluorophosphate anion PF6 - It is preferable that:

[0099] The cationic photopolymerization initiator may be used alone or in combination of two or more. Among them, aromatic sulfonium salts are preferred because they have ultraviolet absorption properties even in the wavelength region around 300 nm, and therefore can form a protective layer with excellent curability and good mechanical strength.

[0100] The content of the cationic photopolymerization initiator in the composition for forming a protective layer is preferably 1 to 10 mass %, more preferably 2 to 8 mass %, based on the solid content of the composition for forming a protective layer. When the content of the cationic photopolymerization initiator is within the above range, the cationic polymerizable compound can be sufficiently cured, and the resulting protective layer can be imparted with high mechanical strength and an enhanced curl suppression effect.

[0101] The protective layer can be formed by forming a coating film of a protective layer-forming composition on the polarizing film produced as described above; removing the solvent from the coating; Polymerizing the cationically polymerizable compound contained in the protective layer-forming composition. It can be produced by a method comprising:

[0102] The method for forming a coating film of the protective layer-forming composition is not particularly limited, and the composition may be applied to the polarizing film produced as described above in the same manner as the method for applying the polarizing film-forming composition. When the protective layer-forming composition contains a solvent, the solvent is usually removed from the applied composition. Methods for removing the solvent include natural drying, forced air drying, heat drying, and reduced pressure drying. The dried coating is preferably dried so that the residual solvent in the protective layer is 1 wt % or less relative to the total mass of the polarizing film. The drying conditions, such as the drying temperature and drying time, can be appropriately determined depending on the composition of the protective layer-forming composition, the materials constituting the polarizing film, and the like.

[0103] The protective layer is preferably produced by irradiating the coating film with active energy rays at room temperature to polymerize the cationically polymerizable compound. Examples of light sources for active energy rays include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources emitting light in the wavelength range of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

[0104] The irradiation energy of the active energy rays may be appropriately determined depending on the type of cationic polymerizable compound contained in the protective layer-forming composition, and the irradiation intensity in the wavelength region effective for activation is 10 to 5000 mJ / cm. 2 It is preferable to set it so that the intensity is within the range of 100 to 2000 mJ / cm. 2 is.

[0105] The protective layer does not function as an adhesive layer. Therefore, in a preferred embodiment of the present invention, when the protective layer is cured, one side of the protective layer is adjacent to the polarizing film, but the other side is not adjacent to another film or the like. In this embodiment, the protective layer is the outermost layer of a polarizing plate including a polarizing film and the protective layer adjacent to the polarizing film.

[0106] From the viewpoint of suppressing the reflectance of the resulting polarizing plate, the in-plane average refractive index of the protective layer is preferably 1.50 to 1.55, more preferably 1.50 to 1.53, and even more preferably 1.50 to 1.52. One method for adjusting the in-plane average refractive index within the above range is to adjust the composition of the protective layer-forming composition, for example.

[0107] (cured resin layer) The polarizing plate of the present invention preferably further comprises a cured resin layer on the polarizing film surface opposite to the surface adjacent to the protective layer. When the polarizing plate is incorporated into a display device, the cured resin layer is usually located on the viewing side, and can enhance the protective function of the polarizing plate.

[0108] The thickness of the cured resin layer is preferably 0.1 to 5 μm, more preferably 0.5 to 4 μm, and even more preferably 0.8 to 3 μm. A thickness of the cured resin layer within the above range is preferred from the viewpoint of suppressing dye diffusion.

[0109] In one embodiment of the present invention, the cured resin layer is preferably a cured product layer of a curable resin composition (also referred to as a "cured resin layer-forming composition") containing an active energy ray-curable component. Examples of the active energy ray-curable component contained in the cured resin layer-forming composition include cationically polymerizable compounds and radically polymerizable compounds. Specific examples of the cationically polymerizable compound include an epoxy compound having one or more epoxy groups in the molecule, an oxetane compound having one or more oxetane rings in the molecule, and a vinyl compound. Specific examples of the radically polymerizable compound include a (meth)acrylic compound having one or more (meth)acryloyl groups in the molecule and a vinyl compound. Among these, the curable resin composition preferably contains a radically polymerizable compound as the active energy ray-curable component, more preferably a (meth)acrylic compound, and even more preferably a polyfunctional (meth)acrylate compound. (Meth)acrylic compounds, particularly polyfunctional (meth)acrylate compounds, are preferred from the viewpoint of suppressing dye diffusion.

[0110] A (meth)acrylic compound is a compound having at least one (meth)acryloyloxy group in the molecule, and may be a monomer, oligomer, or polymer. Examples of (meth)acrylic compounds include (meth)acrylate compounds such as monofunctional (meth)acrylate compounds and polyfunctional (meth)acrylate compounds; urethane (meth)acrylate compounds such as polyfunctional urethane (meth)acrylate compounds; epoxy (meth)acrylate compounds such as polyfunctional epoxy (meth)acrylate compounds; carboxyl group-modified epoxy (meth)acrylate compounds, polyester (meth)acrylate compounds, and the like. One (meth)acrylic compound may be used alone, or two or more may be used in combination. In this specification, "(meth)acrylate" means "acrylate" or "methacrylate," and similarly, "(meth)acryloyl" and the like mean "acryloyl" or "methacryloyl."

[0111] Examples of the (meth)acrylate compound include a monofunctional (meth)acrylate compound having one (meth)acryloyloxy group in the molecule, and a polyfunctional (meth)acrylate compound having two or more (meth)acryloyloxy groups in the molecule.

[0112] An example of a monofunctional (meth)acrylate monomer is alkyl(meth)acrylate. In the alkyl(meth)acrylate, when the alkyl group has three or more carbon atoms, the alkyl(meth)acrylate may be linear or branched. Specific examples of alkyl(meth)acrylate include methyl(meth)acrylate, ethyl(meth)acrylate, isopropyl(meth)acrylate, butyl(meth)acrylate, isobutyl(meth)acrylate, t-butyl(meth)acrylate, and 2-ethylhexyl(meth)acrylate. Also, aralkyl (meth)acrylates such as benzyl (meth)acrylate; (meth)acrylates of terpene alcohols such as isobornyl (meth)acrylate; (meth)acrylates having a tetrahydrofurfuryl structure such as tetrahydrofurfuryl (meth)acrylate; (meth)acrylates having a cycloalkyl group in the alkyl group moiety such as cyclohexyl (meth)acrylate, cyclohexylmethyl methacrylate, dicyclopentanyl acrylate, dicyclopentenyl (meth)acrylate, and 1,4-cyclohexanedimethanol monoacrylate. (Meth)acrylates having a group; aminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate; and (meth)acrylates having an ether bond in the alkyl moiety such as 2-phenoxyethyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, and phenoxypolyethylene glycol (meth)acrylate can also be used as monofunctional (meth)acrylate monomers.

[0113] Examples of bifunctional (meth)acrylate monomers include alkylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate; diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and dipropylene glycol. Polyoxyalkylene glycol di(meth)acrylates such as di(meth)acrylate, tripropylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polytetramethylene glycol di(meth)acrylate; di(meth)acrylates of halogen-substituted alkylene glycols such as tetrafluoroethylene glycol di(meth)acrylate; trimethylolpropane di(meth)acrylate, ditrimethylolpropane di(meth)acrylate di(meth)acrylates of aliphatic polyols such as pentaerythritol di(meth)acrylate; di(meth)acrylates of hydrogenated dicyclopentadiene or tricyclodecane dialkanol such as hydrogenated dicyclopentadienyl di(meth)acrylate and tricyclodecane dimethanol di(meth)acrylate; di(meth)acrylates of dioxane glycol or dioxane dialkanol such as 1,3-dioxane-2,5-diyl di(meth)acrylate (also known as dioxane glycol di(meth)acrylate); bisphenol A esters Di(meth)acrylates of alkylene oxide adducts of bisphenol A or bisphenol F, such as ethylene oxide adduct diacrylate and bisphenol F ethylene oxide adduct diacrylate; epoxy di(meth)acrylates of bisphenol A or bisphenol F, such as acrylic acid adduct of bisphenol A diglycidyl ether and acrylic acid adduct of bisphenol F diglycidyl ether; silicone di(meth)acrylate; di(meth)acrylate of hydroxypivalic acid neopentyl glycol ester;Examples include 2,2-bis[4-(meth)acryloyloxyethoxyethoxyphenyl]propane; 2,2-bis[4-(meth)acryloyloxyethoxyethoxycyclohexyl]propane; di(meth)acrylate of 2-(2-hydroxy-1,1-dimethylethyl)-5-ethyl-5-hydroxymethyl-1,3-dioxane; and tris(hydroxyethyl)isocyanurate di(meth)acrylate.

[0114] The trifunctional (meth)acrylate monomer is a monomer having three (meth)acryloyloxy groups in the molecule, and examples thereof include glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, reaction products of pentaerythritol tri(meth)acrylate and acid anhydride, caprolactone-modified trimethylolpropane tri(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified trimethylolpropane tri(meth)acrylate, tri(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, propylene oxide-modified pentaerythritol tri(meth)acrylate, isocyanurate tri(meth)acrylate, a reaction product of caprolactone-modified pentaerythritol tri(meth)acrylate with an acid anhydride, a reaction product of ethylene oxide-modified pentaerythritol tri(meth)acrylate with an acid anhydride, and a reaction product of propylene oxide-modified pentaerythritol tri(meth)acrylate with an acid anhydride.

[0115] The tetrafunctional (meth)acrylate monomer is a monomer having four (meth)acryloyloxy groups in the molecule, and examples thereof include ditrimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, tripentaerythritol tetra(meth)acrylate, caprolactone-modified pentaerythritol tetra(meth)acrylate, caprolactone-modified tripentaerythritol tetra(meth)acrylate, ethylene oxide-modified pentaerythritol tetra(meth)acrylate, ethylene oxide-modified tripentaerythritol tetra(meth)acrylate, propylene oxide-modified pentaerythritol tetra(meth)acrylate, and propylene oxide-modified tripentaerythritol tetra(meth)acrylate.

[0116] Examples of the pentafunctional (meth)acrylate monomer include dipentaerythritol penta(meth)acrylate, tripentaerythritol penta(meth)acrylate, a reaction product of dipentaerythritol penta(meth)acrylate with an acid anhydride, caprolactone-modified dipentaerythritol penta(meth)acrylate, caprolactone-modified tripentaerythritol penta(meth)acrylate, ethylene oxide-modified dipentaerythritol penta(meth)acrylate, and ethylene oxide-modified tripentaerythritol penta(meth)acrylate. Examples of the dipentaerythritol penta(meth)acrylate include dipentaerythritol penta(meth)acrylate, propylene oxide-modified dipentaerythritol penta(meth)acrylate, propylene oxide-modified tripentaerythritol penta(meth)acrylate, a reaction product of caprolactone-modified dipentaerythritol penta(meth)acrylate with an acid anhydride, a reaction product of ethylene oxide-modified dipentaerythritol penta(meth)acrylate with an acid anhydride, and a reaction product of propylene oxide-modified dipentaerythritol penta(meth)acrylate with an acid anhydride.

[0117] Examples of hexafunctional (meth)acrylate monomers include dipentaerythritol hexa(meth)acrylate, tripentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, caprolactone-modified tripentaerythritol hexa(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified tripentaerythritol hexa(meth)acrylate, propylene oxide-modified dipentaerythritol hexa(meth)acrylate, and propylene oxide-modified tripentaerythritol hexa(meth)acrylate.

[0118] Examples of the heptafunctional (meth)acrylate monomer include tripentaerythritol hepta(meth)acrylate, a reaction product of tripentaerythritol hepta(meth)acrylate and an acid anhydride, caprolactone-modified tripentaerythritol hepta(meth)acrylate, a reaction product of caprolactone-modified tripentaerythritol hepta(meth)acrylate and an acid anhydride, ethylene oxide-modified tripentaerythritol hepta(meth)acrylate, a reaction product of ethylene oxide-modified tripentaerythritol hepta(meth)acrylate and an acid anhydride, propylene oxide-modified tripentaerythritol hepta(meth)acrylate, and a reaction product of propylene oxide-modified tripentaerythritol hepta(meth)acrylate and an acid anhydride.

[0119] The octafunctional (meth)acrylate monomer is a monomer having eight (meth)acryloyloxy groups in the molecule, and examples thereof include tripentaerythritol octa(meth)acrylate, caprolactone-modified tripentaerythritol octa(meth)acrylate, ethylene oxide-modified tripentaerythritol octa(meth)acrylate, and propylene oxide-modified tripentaerythritol octa(meth)acrylate.

[0120] When a polyfunctional (meth)acrylate compound is used, the crosslink density of the cured resin layer can be adjusted by controlling the molecular weight between crosslinks and the number of crosslinks of the compound. More specifically, the smaller the molecular weight between crosslinks, the higher the crosslink density, and the more the number of crosslinks, the denser the crosslink density. This can also improve the diffusion suppression function of the dichroic dye in the polarizing film.

[0121] The urethane (meth)acrylate compound generally refers to a reaction product of an isocyanate compound, a polyol compound, and a (meth)acrylate compound, and is preferably a polyfunctional urethane (meth)acrylate compound having two or more (meth)acryloyloxy groups in the molecule. Polyfunctional urethane (meth)acrylate compounds can form a crosslinked structure, which is advantageous from the viewpoints of improving adhesion to the polarizing film and the function of inhibiting the diffusion of dichroic dyes, and also imparting appropriate toughness. The number of functional groups in the polyfunctional urethane (meth)acrylate compound is preferably 2 to 5.

[0122] In one embodiment of the present invention, the composition for forming a cured resin layer preferably contains a polyfunctional (meth)acrylate compound and a urethane (meth)acrylate compound as radical polymerizable compounds from the viewpoint of suppressing dye diffusion. In this case, the polyfunctional (meth)acrylate compound and the urethane (meth)acrylate compound are preferably contained in a ratio (mass ratio of polyfunctional (meth)acrylate compound:urethane (meth)acrylate compound) of preferably 95:5 to 50:50, more preferably 90:10 to 70:30. By containing the polyfunctional (meth)acrylate compound and the urethane (meth)acrylate compound in the above blending ratio, adhesion to the polarizing film is likely to be improved. The urethane (meth)acrylate compound is preferably a polyfunctional urethane (meth)acrylate compound. The urethane (meth)acrylate compound may be a resin such as an oligomer.

[0123] In one embodiment of the present invention, when the composition for forming a cured resin layer contains a radically polymerizable compound, the radically polymerizable compound preferably contains a (meth)acrylate compound, and more preferably contains a polyfunctional (meth)acrylate compound. In this case, the content of the (meth)acrylate compound (the total content when two or more types are contained) may be preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more, based on 100% by mass of the total amount of the radically polymerizable compounds. When the content of the (meth)acrylate compound, particularly the polyfunctional (meth)acrylate compound, is within the above range, the dichroic dye diffusion suppression function can be enhanced.

[0124] In the above embodiment, the composition for forming a cured resin layer preferably further contains a urethane (meth)acrylate compound as a radically polymerizable compound. In this case, the content of the urethane (meth)acrylate compound is preferably 10% by mass or more, more preferably 15% by mass or more, even more preferably 20% by mass or more, and preferably 60% by mass or less, more preferably 55% by mass or less, even more preferably 50% by mass or less, based on 100% by mass of the total amount of radically polymerizable compounds. When the content of the urethane (meth)acrylate compound is within the above range, adhesion to the polarizing film and the function of suppressing the diffusion of the dichroic dye can be improved.

[0125] In one embodiment of the present invention, when the composition for forming a cured resin layer contains a monofunctional (meth)acrylate compound, the content thereof (the total content thereof when two or more types are contained) is, from the viewpoint of adhesion to the polarizing film, preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, and even more preferably 10% by mass or less, relative to 100% by mass of the total amount of the radically polymerizable compounds.

[0126] When the composition for forming a cured resin layer contains a radically polymerizable compound, it preferably contains a photoradical polymerization initiator. The photoradical polymerization initiator initiates the polymerization reaction of the radically curable compound by irradiation with active energy rays such as visible light, ultraviolet light, X-rays, or electron beams. The photoradical polymerization initiator may be used alone or in combination of two or more.

[0127] Specific examples of the photoradical polymerization initiator include acetophenone-based initiators such as acetophenone, 3-methylacetophenone, benzyl dimethyl ketal, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone-based initiators such as benzophenone, 4-chlorobenzophenone, and 4,4'-diaminobenzophenone; and 2,2-dimethylbenzophenone. Alkylphenone initiators such as 1,2-diphenylethan-1-one and 1-hydroxycyclohexylphenyl ketone; benzoin ether initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone initiators such as 4-isopropylthioxanthone; acylphosphine oxide initiators such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide; and others such as xanthone, fluorenone, camphorquinone, benzaldehyde, and anthraquinone.

[0128] The content of the photoradical polymerization initiator in the composition for forming a cured resin layer is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, per 100 parts by mass of the solid content of the curable compound. When the content of the photoradical polymerization initiator is within the above range, the polymerization initiation ability can be fully exhibited, and the curability can be improved.

[0129] The composition for forming a cured resin layer may contain additives such as a cationic polymerization accelerator, a photosensitizer, an ion trapping agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow adjuster, a plasticizer, an antifoaming agent, an antistatic agent, and a leveling agent, as needed.

[0130] The composition for forming a cured resin layer may contain an organic solvent to adjust the viscosity to a level suitable for the coating method to be used, or may be substantially solvent-free (solvent-free). Note that "substantially solvent-free" does not exclude cases where solvent is inevitably mixed in.

[0131] The solvent may be any solvent capable of dissolving each component of the cured resin layer-forming composition, and may be appropriately selected from aliphatic hydrocarbons such as hexane and octane; aromatic hydrocarbons such as toluene and xylene; alcohols such as ethanol, 1-propanol, isopropanol, and 1-butanol; ketones such as methyl ethyl ketone and methyl isobutyl ketone; esters such as ethyl acetate, butyl acetate, and isobutyl acetate; glycol ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether; and esterified glycol ethers such as ethylene glycol monomethyl ether acetate and propylene glycol monomethyl ether acetate. These solvents may be used alone or in combination of two or more.

[0132] The type and content of the solvent are appropriately selected depending on the type and content of the components constituting the composition for forming a cured resin layer, the shape, the application method, the thickness of the cured resin layer, etc. When a solvent is included, the amount thereof is, for example, preferably 3 to 1000 parts by mass, more preferably 5 to 100 parts by mass, and even more preferably 7 to 50 parts by mass per 100 parts by mass of the solid content of the composition for forming a cured resin layer.

[0133] The cured resin layer can be obtained, for example, by applying a composition for forming a cured resin layer to the surface of a resin film or the polarizing film opposite the protective layer and then irradiating the coating with active energy rays to cure the coating. The method for applying the composition for forming a cured resin layer is not particularly limited, and known methods such as spin coating, extrusion, gravure coating, die coating, bar coating, and applicator coating, and printing methods such as flexography can be used. In one embodiment of the present invention, it is preferable to use a film that has been subjected to a release treatment as the resin film, laminate a cured resin layer on the cured resin layer, and form a polarizing film on the cured resin layer. In this embodiment, it is preferable that the final polarizing plate is a polarizing plate that includes a peelable resin film on the cured resin layer, or a polarizing plate that has, as the outermost layer, a cured resin layer obtained after peeling off the peelable resin film.

[0134] The active energy rays are appropriately selected depending on the type of curable compound, the type of polymerization initiator, and the amounts thereof. Specific examples include visible light, ultraviolet light, infrared light, X-rays, α-rays, β-rays, and γ-rays. Among these, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and photopolymerization devices widely used in this field can be used.

[0135] Examples of light sources for actinic rays include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon lamps, halogen lamps, carbon arc lamps, tungsten lamps, gallium lamps, excimer lasers, LED light sources emitting light in the wavelength range of 380 to 440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

[0136] The ultraviolet irradiation intensity is appropriately determined depending on the composition of the cured resin layer-forming composition and is not particularly limited, but is usually 10 to 3,000 mW / cm 2The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating the polymerization initiator. The light irradiation time is usually 0.1 seconds to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and even more preferably 10 seconds to 1 minute. When irradiating once or multiple times with such ultraviolet irradiation intensity, the cumulative light amount is 10 to 3,000 mJ / cm. 2 , preferably 50 to 2,000 mJ / cm 2 , more preferably 100 to 1,000 mJ / cm 2 The thickness of the cured resin layer is not particularly limited, but may be, for example, 0.1 to 5.0 μm.

[0137] (Layer composition) The polarizing plate of the present invention is not particularly limited as long as it includes a polarizing film and a protective layer adjacent to the polarizing film, and may or may not include layers other than those described above. In a preferred embodiment of the present invention, the polarizing plate of the present invention preferably includes a polarizing film and a protective layer adjacent to each other in this order, and the polarizing film includes a layer made of a cured product of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye, and the layer is adjacent to the protective layer.

[0138] In a preferred embodiment, the polarizing plate of the present invention further comprises a cured resin layer, and comprises a cured resin layer, a polarizing film, and a protective layer adjacent to each other in this order.

[0139] In a preferred embodiment of the present invention, the protective layer adjacent to the polarizing film does not function as an adhesive layer, and therefore the protective layer adjacent to the polarizing film may be one of the outermost layers of the polarizing plate, or may have an adhesive layer on the surface opposite to the surface adjacent to the polarizing film. Therefore, in a preferred embodiment of the present invention, the protective layer included in the polarizing plate of the present invention may be adjacent to the polarizing film on one side and may be the outermost layer of the polarizing plate on the other side, or may have an adhesive layer on the other side.

[0140] In a preferred embodiment of the present invention, the cured resin layer optionally contained in the polarizing plate of the present invention is the outermost layer of the polarizing plate.

[0141] Furthermore, in a preferred embodiment of the present invention, the protective layer included in the polarizing plate of the present invention is adjacent to the polarizing film on one side and is one of the outermost layers of the polarizing plate on the other side, or has an adhesive layer on the other side, and the cured resin layer optionally included in the polarizing plate is the other outermost layer of the polarizing plate. When the protective layer and / or the cured resin layer is the outermost layer of the polarizing plate of the present invention, a peelable release film may be laminated on the outermost layer. A polarizing plate of the present invention having such a configuration is expected to have excellent reflective appearance and further improved curl suppression effect.

[0142] The polarizing plate of the present invention may contain layers other than the above-described layers as long as they do not affect the effects of the present invention. Examples of such layers include an adhesive layer for bonding with a retardation layer, etc., which will be described later, a protective film, a separation film, an antistatic layer, etc.

[0143] <Circular polarizer> The polarizing plate of the present invention is excellent in suppressing curling and the diffusion of dichroic dyes and the like from the polarizing film into other layers, and also has excellent reflective appearance during black display, so that it is expected to have high optical properties and can be suitably used as a constituent material for liquid crystal displays, organic electroluminescence (EL) displays, and the like. The polarizing plate of the present invention can also be used as a circular polarizing plate in combination with a retardation film. In a preferred embodiment of the present invention, the polarizing plate of the present invention may be used as a circular polarizing plate in which the polarizing plate and the retardation film are laminated via an adhesive layer, and the protective layer of the polarizing plate, the adhesive layer, and the retardation film are adjacent in this order. Therefore, the present invention also provides a circular polarizing plate in which the polarizing plate of the present invention and the retardation film are laminated via an adhesive layer, and the protective layer of the polarizing plate, the adhesive layer, and the retardation film are adjacent in this order.

[0144] (phase contrast film) The retardation film included in the circular polarizer is preferably composed of a polymer of a polymerizable liquid crystal compound. When the retardation film is a cured layer (cured film) of a polymerizable liquid crystal compound, a thinner circular polarizer can be formed compared to when the layer having retardation is made of a stretched film, but curling is more likely to occur due to the retardation film being thin (for example, 5 μm or less). The optical laminate of the present invention has a specific protective layer, so curling can be suppressed.

[0145] From the viewpoint of making the above-mentioned effect more pronounced, in one embodiment of the present invention, the thickness of the retardation film 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. In the present invention, the retardation film is a film that exhibits retardation in the in-plane or thickness direction, and may be a layer made of a polymer of a polymerizable liquid crystal compound alone, or may be a layer made of the polymer and, if an alignment film for forming the polymer is present adjacent to the layer, the alignment film. When the retardation film includes an alignment film, the thickness of the retardation film does not include the thickness of the alignment film.

[0146] In this specification, the retardation film may include one or more retardation films. When two or more retardation films are included, the thickness of each retardation film can be appropriately determined depending on the optical properties required for each retardation film, the configuration and use of the optical laminate, etc., and the thicknesses may be the same or different from each other.

[0147] In order for the polarizing plate of the present invention to function as a circular polarizing plate, the circular polarizing plate has a structure represented by the following formula (1): 120nm≦Re(550)≦170nm (1) (wherein Re(λ) represents the in-plane retardation value of the retardation film at a wavelength of λ nm) That is, when the circularly polarizing plate of the present invention includes only one retardation film, the retardation film preferably satisfies the above formula (1). When the in-plane retardation Re(550) of the retardation film is within the range of formula (1), the retardation film functions as a quarter-wave plate, and the effect of improving the front reflection hue (the effect of suppressing coloration) is likely to be enhanced when a circular polarizer including the retardation film is applied to an organic EL display device, etc. A more preferable range of the in-plane retardation value is 130 nm≦Re(550)≦150 nm.

[0148] In addition to formula (4), the retardation film may also be represented by the following formulas (2) and (3): Re(450) / Re(550)≦1.00 (2) 1.00≦Re(650) / Re(550) (3) (wherein Re(λ) represents the in-plane retardation value of the retardation film at a wavelength of λ nm) It is preferable that the following is satisfied. When the retardation film satisfies formulas (2) and (3), the retardation film exhibits so-called reverse wavelength dispersion, in which the in-plane retardation value at short wavelengths is smaller than the in-plane retardation value at long wavelengths. A circularly polarizing plate having such a retardation film tends to have excellent front hue when incorporated into an organic EL display device or the like. From the viewpoint of improving the reverse wavelength dispersion and further enhancing the effect of improving the reflected hue in the front direction, Re(450) / Re(550) is preferably 0.70 or more, more preferably 0.78 or more, and also preferably 0.92 or less, more preferably 0.90 or less, even more preferably 0.87 or less, particularly preferably 0.86 or less, and even more particularly preferably 0.85 or less. Furthermore, Re(650) / Re(550) is preferably 1.01 or more, more preferably 1.02 or more.

[0149] The in-plane retardation value can be adjusted by the film thickness dA of the retardation film. The in-plane retardation value is determined by the formula ReA(λ) = (nxA(λ) - nyA(λ)) × dA [where nxA(λ) represents the principal refractive index at a wavelength of λ nm in the plane of the retardation film, nyA(λ) represents the refractive index at a wavelength of λ nm in the direction orthogonal to the direction of nxA in the same plane as nxA, and dA indicates the film thickness of the retardation film]. Therefore, in order to obtain a desired in-plane retardation value (ReA(λ): the in-plane retardation value of the retardation film at a wavelength of λ (nm)), it is only necessary to adjust the three-dimensional refractive index and the film thickness dA.

[0150] The optical laminate of the present invention preferably includes a retardation film composed of a "horizontally aligned liquid crystal cured film" in which the polymerizable liquid crystal compound is cured in a state of being horizontally aligned with respect to the plane of the retardation film. When the optical laminate of the present invention includes only one retardation film, usually, the retardation film is a "horizontally aligned liquid crystal cured film", and preferably satisfies the above formulas (1) to (3).

[0151] Examples of the retardation film that the circular polarizing plate of the present invention may include are a retardation film that is a positive C plate (nx ≈ ny < nz), a retardation film having a half-wave plate function, and the like. The retardation film that is a positive C plate is a "vertically aligned liquid crystal cured film" in which the polymerizable liquid crystal compound is cured in a state of being vertically aligned with respect to the plane of the retardation film. By combining a retardation film having a quarter-wave plate function and a retardation film that is a positive C plate, when the circular polarizing plate is applied to an organic EL display device or the like, in addition to the improvement of the front reflection color phase, an improvement in the oblique reflection color phase can also be expected.

[0152] The polymerizable liquid crystal compound capable of forming the retardation film in the present invention can be appropriately selected from polymerizable liquid crystal compounds conventionally known in the field of retardation films according to the desired optical properties. Polymerizable liquid crystal compounds usable in the present invention can be classified, for example, into rod-shaped types (rod-shaped liquid crystal compounds) and discotic types (discotic liquid crystal compounds, discotic liquid crystal compounds) based on their shape, and any liquid crystal compound can be used. Furthermore, a mixture of two or more rod-shaped liquid crystal compounds, two or more discotic liquid crystal compounds, or a mixture of a rod-shaped liquid crystal compound and a discotic liquid crystal compound may be used.

[0153] The polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable group. Generally, the polymerizable liquid crystal compound is polymerized alone in a state where the polymerizable liquid crystal compound is aligned in a specific direction, and the polymer (cured product) obtained by polymerizing the polymerizable liquid crystal compound alone exhibits positive wavelength dispersion, and the polymerizable liquid crystal compound exhibits reverse wavelength dispersion. In the present invention, only one type of polymerizable liquid crystal compound may be used, or both types of polymerizable liquid crystal compounds may be mixed and used.

[0154] In the present invention, the polymerizable group possessed by the polymerizable liquid crystal compound forming the retardation film is preferably a photopolymerizable group. Examples of the photopolymerizable group include the same as those exemplified as the polymerizable group that may be possessed by the polymerizable liquid crystal compound forming the polarizing film. The liquid crystal property exhibited by the polymerizable liquid crystal compound may be thermotropic or lyotropic, but thermotropic liquid crystal is preferred in terms of enabling precise film thickness control. Furthermore, the phase-ordered structure in the thermotropic liquid crystal may be nematic, smectic, or discotic. The polymerizable liquid crystal compounds may be used alone or in combination of two or more.

[0155] As the polymerizable liquid crystal compound (hereinafter also referred to as "polymerizable liquid crystal compound (B)") that forms the retardation film, compounds that satisfy all of the following (a) to (d) can be mentioned, from the viewpoint of imparting the retardation properties represented by the above formulas (2) and (3).

[0156] (A) A compound having thermotropic liquid crystal properties; (a) The polymerizable liquid crystal compound has π electrons in the long axis direction (a). (c) It has π electrons in a direction intersecting the long axis direction (a) [intersecting direction (b)]. (D) The π electron density in the long axis direction (a) of a polymerizable liquid crystal compound defined by the following formula (i), where N(πa) is the total number of π electrons present in the long axis direction (a) and N(Aa) is the total number of molecular weights present in the long axis direction: D(πa)=N(πa) / N(Aa) (i) The π electron density in the cross direction (b) of the polymerizable liquid crystal compound is defined by the following formula (ii), where N(πb) is the total number of π electrons present in the cross direction (b) and N(Ab) is the total molecular weight present in the cross direction (b): D(πb)=N(πb) / N(Ab) (ii) But, 0≦[D(πa) / D(πb)]≦1 (i.e., the π electron density in the cross direction (b) is greater than the π electron density in the long axis direction (a)). The polymerizable liquid crystal compound (B) satisfying all of the above (A) to (D) can form a nematic phase or a smectic phase, for example, by heating it to a temperature equal to or higher than the phase transition temperature. In the nematic phase or smectic phase formed by the orientation of this polymerizable liquid crystal compound, the long axes of the polymerizable liquid crystal compounds are usually aligned so as to be parallel to each other, and these long axes become the orientation direction of the nematic phase or smectic phase.

[0157] The polymerizable liquid crystal compound (B) having the above characteristics generally exhibits reverse wavelength dispersion. Specific examples of the compound satisfying the above characteristics (a) to (d) include compounds represented by the following formula (B1): [ka] The compounds represented by formula (B1) can be used alone or in combination of two or more.

[0158] In formula (B1), Ar represents a divalent group having an aromatic group which may have a substituent. Examples of the aromatic group include the groups exemplified by (Ar-1) to (Ar-23) described below. Ar may also have two or more aromatic groups. The aromatic group may contain at least one of a nitrogen atom, an oxygen atom, and a sulfur atom. When Ar contains two or more aromatic groups, the two or more aromatic groups may be bonded to each other via a divalent bonding group such as a single bond, -CO-O-, or -O-.

[0159] In formula (B1), G 1 and G 2 each independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with 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 a carbon atom constituting the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom.

[0160] In formula (B1), L 1 , L 2 , B 1 and B 2 are each independently a single bond or a divalent linking group.

[0161] In formula (B1), k and l each independently represent an integer of 0 to 3, and satisfy the relationship 1≦k+l. When 2≦k+l, B 1 and B 2 , G 1 and G 2 may be the same as or different from each other.

[0162] In formula (B1), E 1 and E 2are each independently an alkanediyl group having 1 to 17 carbon atoms, and more preferably an alkanediyl group having 4 to 12 carbon atoms. Furthermore, a hydrogen atom contained in the alkanediyl group may be substituted with a halogen atom, and -CH2- contained in the alkanediyl group may be substituted with -O-, -S-, or -C(=O)-.

[0163] In formula (X), P 1 and P 2 each independently represents a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group.

[0164] G 1 and G 2 are each independently preferably a 1,4-phenylenediyl group optionally substituted with at least one substituent selected from the group consisting of halogen atoms and alkyl groups having 1 to 4 carbon atoms, or a 1,4-cyclohexanediyl group optionally substituted with at least one substituent selected from the group consisting of halogen atoms and alkyl groups having 1 to 4 carbon atoms, more preferably a 1,4-phenylenediyl group substituted with a methyl group, an unsubstituted 1,4-phenylenediyl group, or an unsubstituted 1,4-trans-cyclohexanediyl group, and particularly preferably an unsubstituted 1,4-phenylenediyl group or an unsubstituted 1,4-trans-cyclohexanediyl group. Also, there are multiple G 1 and G 2 At least one of L is preferably a divalent alicyclic hydrocarbon group. 1 or L 2 G binds to 1 and G 2 It is more preferable that at least one of the groups is a divalent alicyclic hydrocarbon group.

[0165] L 1 and L 2 are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R a1 OR a2 -, -R a3 COOR a4 -, -Ra5 OCOR a6 -, -R a7 OC=OOR a8 -, -N=N-, -CR c =CR d -, or -C≡C-, where R a1 ~R a8 each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms, and R c and R d represents an alkyl group having 1 to 4 carbon atoms or a hydrogen atom. 1 and L 2 are each independently preferably a single bond, -OR a2-1 -, -CH2-, -CH2CH2-, -COOR a4-1 -, or -OCOR a6-1 -, where R a2-1 , R a4-1 , R a6-1 Each independently represents a single bond, -CH2-, or -CH2CH2-. 1 and L 2 are each independently more preferably a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, or -OCO-.

[0166] B 1 and B 2 are each independently preferably a single bond, an alkylene group having 1 to 4 carbon atoms, -O-, -S-, -R a9 OR a10 -, -R a11 COOR a12 -, -R a13 OCOR a14 -, or -R a15 OC=OOR a16 -, where R a9 ~R a16 each independently represents a single bond or an alkylene group having 1 to 4 carbon atoms. 1 and B 2 are each independently preferably a single bond, -OR a10-1 -, -CH2-, -CH2CH2-, -COOR a12-1 -, or -OCOR a14-1 -, where Ra10-1 , R a12-1 , R a14-1 Each independently represents a single bond, -CH2-, or -CH2CH2-. B 1 and B 2 are each independently more preferably a single bond, -O-, -CH2CH2-, -COO-, -COOCH2CH2-, -OCO-, or -OCOCH2CH2-.

[0167] From the viewpoint of exhibiting reverse 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. When k=2 and l=2, a symmetric structure is obtained, which is preferable.

[0168] P 1 or P 2 Examples of the polymerizable group represented by the formula (I) include an epoxy group, a vinyl group, a vinyloxy group, a 1-chlorovinyl group, an isopropenyl group, a 4-vinylphenyl group, a (meth)acryloyl group, an oxiranyl group, and an oxetanyl group. Among these, a (meth)acryloyl group, a vinyl group, and a vinyloxy group are preferred, and a (meth)acryloyl group is more preferred.

[0169] Ar preferably has at least one selected from an aromatic hydrocarbon ring which may have a substituent, an aromatic heterocyclic ring which may have a substituent, and an electron-withdrawing group. Examples of the aromatic hydrocarbon ring include a benzene ring, a naphthalene ring, and an anthracene ring, with a benzene ring and a naphthalene ring being preferred. Examples of the aromatic heterocyclic ring include a furan ring, a benzofuran ring, a pyrrole ring, an indole ring, a thiophene ring, a benzothiophene ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, a triazole ring, a triazine ring, a pyrroline ring, an imidazole ring, a pyrazole ring, a thiazole ring, a benzothiazole ring, a thienothiazole ring, an oxazole ring, a benzoxazole ring, and a phenanthroline ring. 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, it is preferred that the nitrogen atom has π electrons.

[0170] In formula (B1), the total number of π electrons possessed by the group represented by Ar is N π is usually 6 or more, preferably 8 or more, more preferably 10 or more, even more preferably 14 or more, and particularly preferably 16 or more. It is also preferably 36 or less, more preferably 32 or less, even more preferably 26 or less, and particularly preferably 24 or less.

[0171] Examples of the aromatic group contained in Ar include the following groups.

[0172] [ka]

[0173] In formulas (Ar-1) to (Ar-23), * represents a linking portion, and Z 0 , Z 1 and Z 2each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cyano group, a nitro group, an alkylsulfinyl group having 1 to 12 carbon atoms, an alkylsulfonyl group having 1 to 12 carbon atoms, a carboxyl group, a fluoroalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, an alkylthio group having 1 to 12 carbon atoms, an N-alkylamino group having 1 to 12 carbon atoms, an N,N-dialkylamino group having 2 to 12 carbon atoms, an N-alkylsulfamoyl group having 1 to 12 carbon atoms, or an N,N-dialkylsulfamoyl group having 2 to 12 carbon atoms. 0 , Z 1 and Z 2 may contain a polymerizable group.

[0174] In formula (Ar-1) ~ formula (Ar-23), Q 1 and Q 2 are each independently -CR 2’ R 3’ -, -S-, -NH-, -NR 2’ represents -, -CO- or -O-, and R 2’ and R 3’ each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

[0175] In formula (Ar-1) ~ formula (Ar-23), J 1 and J. 2 each independently represents a carbon atom or a nitrogen atom.

[0176] In formula (Ar-1) ~ formula (Ar-23), Y 1 , Y 2 and Y 3 each independently represents an optionally substituted aromatic hydrocarbon group or an optionally substituted aromatic heterocyclic group.

[0177] In formulas (Ar-1) to (Ar-23), W 1 and W 2 each independently represents a hydrogen atom, a cyano group, a methyl group or a halogen atom; and m represents an integer of 0 to 6.

[0178] Y 1 , Y 2and Y 3 Examples of the aromatic hydrocarbon group in the formula (I) include aromatic hydrocarbon groups having 6 to 20 carbon atoms, such as a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, and a biphenyl group, with a phenyl group and a naphthyl group being preferred, and a phenyl group being more preferred. Examples of the aromatic heterocyclic group include aromatic heterocyclic groups having 4 to 20 carbon atoms and containing at least one heteroatom, such as a nitrogen atom, an oxygen atom, or a sulfur atom, such as a furyl group, a pyrrolyl group, a thienyl group, a pyridinyl group, a thiazolyl group, and a benzothiazolyl group being preferred.

[0179] Y 1 , Y 2 and Y 3 may each independently be an optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group. The polycyclic aromatic hydrocarbon group refers to a fused polycyclic aromatic hydrocarbon group or a group derived from an aromatic ring assembly. The polycyclic aromatic heterocyclic group refers to a fused polycyclic aromatic heterocyclic group or a group derived from an aromatic ring assembly.

[0180] Z 0 , Z 1 and Z 2 are each independently preferably 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, and Z 0 is more preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, or a cyano group, and Z 1 and Z 2 is more preferably a hydrogen atom, a fluorine atom, a chlorine atom, a methyl group, or a cyano group. 0 , Z 1 and Z 2 may contain a polymerizable group.

[0181] Q 1 and Q 2 -NH-, -S-, -NR 2’ -, -O- are preferred, and R 2’ is preferably a hydrogen atom, and among these, -S-, -O-, and -NH- are particularly preferred.

[0182] Among the formulae (Ar-1) to (Ar-23), the formulae (Ar-6) and (Ar-7) are preferred from the viewpoint of molecular stability.

[0183] In formulas (Ar-16) to (Ar-23), Y 1 is the nitrogen atom to which it is bonded and Z 0 and Y may form an aromatic heterocyclic group together. Examples of the aromatic heterocyclic group include those mentioned above as aromatic heterocycles that Ar may have, such as a pyrrole ring, an imidazole ring, a pyrroline ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an indole ring, a quinoline ring, an isoquinoline ring, a purine ring, and a pyrrolidine ring. This aromatic heterocyclic group may have a substituent. In addition, Y 1 is the nitrogen atom to which it is bonded and Z 0 and may be the above-mentioned optionally substituted polycyclic aromatic hydrocarbon group or polycyclic aromatic heterocyclic group, such as a benzofuran ring, a benzothiazole ring, or a benzoxazole ring.

[0184] The compound represented by formula (B1) can be produced, for example, according to the method described in JP-A-2010-31223.

[0185] The polymerizable liquid crystal composition for forming a retardation film (hereinafter also referred to as "retardation film-forming composition") may contain other polymerizable liquid crystal compounds than the polymerizable liquid crystal compound (B1) as long as the effects of the present invention are not impaired. When the retardation film-forming composition contains two or more polymerizable liquid crystal compounds, from the viewpoint of obtaining a retardation film having excellent optical properties, it is preferable that at least one of them is the polymerizable liquid crystal compound (B1), and all of the compounds contained in the retardation film-forming composition may be the polymerizable liquid crystal compound (B1).

[0186] The content of the polymerizable liquid crystal compound (B) in the composition for forming a retardation film is preferably 60 to 99.9 mass %, more preferably 70 to 99.9 mass %, and even more preferably 80 to 99 mass %, based on the solid content of the composition for forming a polarizing film. When the content of the polymerizable liquid crystal compound is within the above range, the orientation of the polymerizable liquid crystal compound tends to be high.

[0187] The retardation film-forming composition may contain a polymerization initiator for initiating the polymerization reaction of the polymerizable liquid crystal compound. The polymerization initiator may be appropriately selected from those conventionally used in the field, and may be a thermal polymerization initiator or a photopolymerization initiator. However, a photopolymerization initiator is preferred because it can initiate the polymerization reaction under lower temperature conditions. Suitable examples of the photopolymerization initiator usable in the polarizing film-forming composition include those previously exemplified. Furthermore, the retardation film-forming composition may contain, as necessary, a photosensitizer, a leveling agent, and additives such as those exemplified as additives contained in the polarizing film-forming composition. Examples of the photosensitizer and leveling agent include those previously exemplified as those usable in the polarizer-forming composition.

[0188] The retardation film-forming composition is prepared, for example, by mixing and stirring a polymerizable liquid crystal compound and, if necessary, a polymerization initiator, additives, etc. In addition, in order to improve the coating property, a solvent may be added to the retardation film-forming composition to adjust the viscosity. Examples of the solvent include the solvents exemplified above as the solvent contained in the polarizer-forming composition.

[0189] The retardation film can be obtained by applying a retardation film-forming composition onto a substrate or an alignment film, removing the solvent by drying, and curing the polymerizable liquid crystal compound in the resulting coating film in an aligned state. Examples of the alignment film include the same ones as those exemplified above as those that can be used when producing a polarizing film.

[0190] The coating method of the retardation film-forming composition, the conditions for curing with active energy rays, and the like may be the same as those that can be employed in the method for producing a polarizing film.

[0191] When a retardation film is laminated on a polarizing plate, it is preferable to laminate the retardation film so that the slow axis (optical axis) of the retardation film and the absorption axis of the polarizing film form an angle of substantially 45°. By laminating the retardation film so that the slow axis (optical axis) of the retardation film and the absorption axis of the polarizing film form an angle of substantially 45°, it is possible to obtain the function of a circular polarizing plate. Note that substantially 45° is usually in the range of 45±5°. The polarizing plate and the retardation film can be laminated via an adhesive layer formed, for example, from an adhesive.

[0192] (Laminating layer) In the circular polarizing plate of the present invention, the polarizing plate and the retardation film are laminated via an adhesive layer. The adhesive layer is a layer formed from a pressure-sensitive adhesive. The adhesive layer is not particularly limited as long as it can function as a layer for bonding the polarizing plate, particularly the protective layer of the polarizing plate, to the retardation film, and may be a layer formed from a known pressure-sensitive adhesive. The adhesive or adhesive is not particularly limited, and conventionally known pressure-sensitive adhesives and adhesives can be used without particular restriction. Examples of the adhesive include pressure-sensitive adhesives having a base polymer such as acrylic, rubber, urethane, silicone, and polyvinyl ether. Energy ray-curable adhesives and heat-curable adhesives may also be used. Examples of the adhesive include active energy ray-curable adhesives, water-based adhesives, organic solvent-based adhesives, and solventless adhesives.

[0193] The thickness of the laminating layer is preferably 1 to 10 μm, more preferably 3 to 8 μm, from the viewpoint of reducing the thickness of the circularly polarizing plate.

[0194] The polarizing plate and circular polarizing plate of the present invention are less likely to curl during production, are easy to handle when producing an image display device or the like that includes the polarizing plate or circular polarizing plate, and are easily transferred to a transfer target material. Furthermore, they have an excellent reflective appearance effect, are less likely to curl over time, and are expected to have high optical performance. Therefore, the polarizing plate and circular polarizing plate of the present invention are suitable as components of various display devices. A display device is a device having a display element, and includes a light-emitting element or a light-emitting device as a light source. Examples of display devices include liquid crystal display devices, organic electroluminescence (EL) display devices, inorganic electroluminescence (EL) display devices, touch panel display devices, electron emission display devices (e.g., field emission displays (FEDs) and surface field emission displays (SEDs)), electronic paper (display devices using electronic ink or electrophoretic elements), plasma display devices, projection display devices (e.g., grating light valve (GLV) displays and displays having a digital micromirror device (DMD)), and piezoelectric ceramic displays. Liquid crystal display devices include any of transmissive liquid crystal display devices, semi-transmissive liquid crystal display devices, reflective liquid crystal display devices, direct-view liquid crystal display devices, and projection liquid crystal display devices. These display devices may be displays that display two-dimensional images or stereoscopic display devices that display three-dimensional images. In particular, the polarizing plate and circular polarizing plate of the present invention can be suitably used in organic electroluminescence (EL) display devices and inorganic electroluminescence (EL) display devices, and can also be suitably used in liquid crystal display devices and touch panel display devices. These display devices can exhibit good image display characteristics because the polarizing plate and circular polarizing plate of the present invention have an excellent reflective appearance effect and high visibility. [Example]

[0195] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Hereinafter, the parts and percentages representing amounts used and contents are by mass unless otherwise specified.

[0196] 1. Preparation of Cured Resin Layer and Horizontal Polarizer (1) Preparation of the composition (i) Preparation of composition for forming cured resin layer The following components were mixed and stirred at 50° C. for 4 hours to obtain a composition for forming a cured resin layer. Polyfunctional acrylate monomer [dipentaerythritol hexaacrylate]: 70 parts [ka] Urethane acrylate resin [EBECRYL 4858 (manufactured by Daicel Allnex Co., Ltd.)]: 30 parts Polymerization initiator [2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one [Omnirad 907 (manufactured by IGM Resins BV)]]: 3 parts Solvent [methyl ethyl ketone]: 10 parts

[0197] (ii) Preparation of composition (1) for forming a photo-alignment film A copolymer having the following structure was prepared by the following procedure: Copolymer: [ka]

[0198] Chlorodimethyl ether was added dropwise to a solution of 4-((6-(methacryloyloxy)hexyl)oxy)benzoic acid dissolved in toluene together with an amine catalyst, and the reaction was allowed to proceed by heating and maintaining the temperature at 40°C. The reaction solution was then cooled and water was added. A 50% aqueous solution of acetic acid was added to the separated organic layer and stirred. The separated organic layer was concentrated to obtain methoxymethyl 4-((6-(methacryloyloxy)hexyl)oxy)benzoate. 8.8 g (25.2 mmol) of methoxymethyl 4-((6-(methacryloyloxy)hexyl)oxy)benzoate, 1.0 g (3.6 mmol) of 6-(4-hydroxyphenoxy)hexyl methacrylate, 3.2 g (7.2 mmol) of 4-((6-(methacryloyloxy)hexyl)oxy)phenyl(E)-3-(4-methoxyphenyl)acrylate, and 0.2 g of 2,2'-azobis(2,4-dimethylvaleronitrile) were dissolved in tetrahydrofuran. Nitrogen was bubbled through the solution for 1 hour, and the reaction was allowed to proceed by heating and maintaining the temperature at 60°C. The reaction solution was then cooled to room temperature. 1.1 g (3.6 mmol) of 4-((6-(methacryloyloxy)hexyl)oxy)benzoic acid and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride were added to the reaction solution to obtain a mixed solution. The reaction was allowed to proceed by heating the mixture to 40°C, and then the reaction mixture was cooled. Methanesulfonic acid was added to the reaction mixture at room temperature, and the mixture was heated to 70°C. The reaction mixture was then cooled to approximately room temperature. The cooled reaction mixture was added dropwise to normal hexane to produce a precipitate. The precipitate was collected and dried under reduced pressure to obtain a polymer (copolymer). The weight-average molecular weight of the resulting copolymer was measured by GPC and found to be 24,000.

[0199] The 4-((6-(methacryloyloxy)hexyl)oxy)phenyl(E)-3-(4-methoxyphenyl)acrylate and 4-((6-(methacryloyloxy)hexyl)oxy)benzoic acid used above were prepared by the following procedure.

[0200] 4-((6-(methacryloyloxy)hexyl)oxy)phenyl(E)-3-(4-methoxyphenyl)acrylate [ka]

[0201] 6-(4-hydroxyphenoxy)-1-bromohexane was synthesized by heating 1,4-dihydroxybenzene and 1,6-dibromohexane under alkaline conditions. This product was reacted with lithium methacrylate to synthesize 6-(4-hydroxyphenoxy)hexyl methacrylate. To this was added p-methoxycinnamic acid chloride under basic conditions to synthesize 4-((6-(methacryloyloxy)hexyl)oxy)phenyl (E)-3-(4-methoxyphenyl)acrylate.

[0202] 4-((6-(methacryloyloxy)hexyl)oxy)benzoic acid [ka]

[0203] It was synthesized using methacrylic acid chloride as a raw material according to the method described in Makromol. Chem., 190, pp. 2255-2268, 1989.

[0204] 2 parts of the obtained copolymer and 98 parts of propylene glycol methyl ether acetate were mixed, and the mixture was stirred at 80° C. for 1 hour to obtain a composition (1) for forming a photo-alignment film.

[0205] (iii) Preparation of composition for forming horizontal polarizing film The following components were mixed and stirred at 80°C for 1 hour to obtain a composition for forming a horizontal polarizing film. The polymerizable liquid crystal compounds (A1) and (A2) have the structures shown below. The dichroic dyes (DP1) to (DP3) are azo dyes described in the examples of JP 2013-101328 A and have the structures shown below. Polymerizable liquid crystal compound (A1): 75 parts Polymerizable liquid crystal compound (A2): 25 parts Dichroic dye (DP1): 2.5 parts Dichroic dye (DP2): 2.5 parts Dichroic dye (DP3): 2.5 parts Polymerization initiator [2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure (registered trademark) 369; manufactured by BASF Japan Ltd.)]: 6 parts Leveling agent [polyacrylate compound (BYK-361N; manufactured by BYK-Chemie)]: 1.2 parts Solvent [o-xylene]: 250 parts

[0206] ·Polymerizable liquid crystal compound (A1): [ka] ·Polymerizable liquid crystal compound (A2): [ka]

[0207] ·Dichroic dye (DP1): [ka] Dichroic dye (DP2): [ka] Dichroic dye (DP3): [ka]

[0208] (2) Preparation of laminated film with polarizing film (i) Preparation of cured resin layer After corona treatment was performed on the release-treated surface of a release-treated polyethylene terephthalate film (SP-PLR382050 manufactured by Lintec Corporation) (release film), the composition for forming a cured resin layer was applied by a bar coating method (#2 30 mm / s) and dried by heating in a drying oven set at 80°C for 1 minute to obtain a dried coating. Next, using a UV irradiation device (UniCure VB-15201BY-A manufactured by Ushio Inc.), ultraviolet light was irradiated onto the dried coating of the composition for forming a cured resin layer (under a nitrogen atmosphere, cumulative light dose at a wavelength of 365 nm: 500 mJ / cm). 2) to obtain a release film with a cured resin layer, in which a cured resin layer was formed on the surface of the release film. The thickness of the obtained cured resin layer was measured using an ellipsometer M-220 (manufactured by JASCO Corporation) and was found to be 1.5 μm.

[0209] (ii) Preparation of horizontal polarizing film Next, the surface of the cured resin layer of the release film with the cured resin layer was subjected to a corona treatment once using a corona treatment device (AGF-B10; manufactured by Kasuga Electric Co., Ltd.) under conditions of an output of 0.3 kW and a treatment speed of 3 m / min. The photoalignment film-forming composition (1) was applied to the corona-treated surface using a bar coater, dried at 80°C for 1 minute, and then irradiated with 50 mJ / cm using a polarized UV irradiation device (SPOT CURE SP-9 with polarizer unit; manufactured by Ushio Inc.). 2 Polarized UV exposure (in air, cumulative light intensity at wavelength 313 nm: 50 mJ / cm 2 ) was carried out to form a photo-alignment film (1). The thickness of the obtained photo-alignment film (1) was measured with an ellipsometer M-220 (manufactured by JASCO Corporation) and was found to be 100 nm.

[0210] A composition for forming a horizontal polarizing film was applied onto the obtained photo-alignment film (1) using a bar coater, and then heated and dried for 1 minute in a drying oven set at 120°C to obtain a dried film. Next, using a UV irradiation device (UniCure VB-15201BY-A, manufactured by Ushio Inc.), ultraviolet light was irradiated onto the dried film surface of the composition for forming a polarizing film (under a nitrogen atmosphere, cumulative light intensity at a wavelength of 365 nm: 500 mJ / cm). 2By this process, a polarizing film in which the polymerizable liquid crystal compound and dichroic dye were aligned horizontally relative to the film surface was formed, yielding a laminate film with a horizontal polarizing film consisting of a release film, a cured resin layer, a photoalignment film, and a horizontal polarizing film. The thickness of the polarizing film was measured using an M-220 ellipsometer (manufactured by JASCO Corporation) and found to be 2.0 μm. Next, X-ray diffraction measurements of the polarizing film were performed using an X'Pert PRO MPD X-ray diffractometer (manufactured by Spectris Inc.). A sharp diffraction peak (Bragg peak) with a full width at half maximum (FWHM) of approximately 0.17° was observed near 2θ = 20.2°. The order period (d) calculated from the peak position was approximately 4.4 Å, confirming the formation of a structure reflecting a high-order smectic phase.

[0211] [Measurement of weight-average molecular weight] The weight average molecular weight (Mw) was measured using a GPC system with a TSKgel GMH column manufactured by Tosoh Corporation. HR Two "-H(S)" were connected in series, and tetrahydrofuran was used as the eluent. Measurements were performed in terms of standard polystyrene under the following conditions: sample concentration 2 mg / mL, sample introduction volume 100 μL, temperature 40°C, and flow rate 1 mL / min.

[0212] 2. Preparation of the Protective Layer (1) Preparation of the composition (i) Preparation of protective layer-forming composition (1) The components shown below were mixed in the following proportions (unit: parts by mass) to obtain a composition (1) for forming a protective layer. Epoxy compound 1 [3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (product name: CEL2021P, manufactured by Daicel Corporation)]: 32.5 parts Epoxy compound 2 [1,2-epoxy-4-(2-oxiranyl)cyclohexane adduct of 2,2-bis(hydroxymethyl)-1-butanol (trade name: EHPE3150, manufactured by Daicel Corporation)]: 7.5 parts 60 parts of oxetane compound [3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane (product name: OXT-221, manufactured by Toagosei Co., Ltd.)] Polymerization initiator [cationic polymerization initiator (product name: CPI-100P, 50% by mass solution, manufactured by San-Apro Co., Ltd.)]: 2.25 parts Photosensitizer coagent [E-1: 1,4-diethoxynaphthalene]: 2 parts Leveling agent [silicone leveling agent (product name: SH710, manufactured by Toray Dow Corning Co., Ltd.)]: 0.25 parts

[0213] (ii) Preparation of protective layer-forming composition (2) The components shown below were mixed in the following proportions (unit: parts by mass) and then degassed to obtain a protective layer-forming composition (2). The cationic polymerization initiator was blended as a 50% propylene carbonate solution, and the solid content is shown. 40 parts of polyfunctional aromatic epoxy resin [bisphenol A epoxy resin (trade name: jER828, manufactured by Mitsubishi Chemical Corporation, viscosity 13 Pa·s (temperature 25°C)]] Alicyclic epoxy resin [3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (product name: CEL2021P, manufactured by Daicel Corporation, viscosity 0.25 Pa·s (temperature 25°C)]: 7 parts by mass Polyfunctional aliphatic epoxy resin [neopentyl glycol diglycidyl ether (product name: EX-211L, manufactured by Nagase ChemteX Corporation, viscosity 0.02 Pa·s (temperature 25°C)]: 33 parts by mass Oxetane resin [3-ethyl-3-(phenoxymethyl)oxetane (product name: OXT-211, manufactured by Toagosei Co., Ltd., viscosity 0.014 Pa·s (temperature 25°C)]: 20 parts by mass Cationic polymerization initiator [cationic polymerization initiator (product name: CPI-100P, manufactured by San-Apro Co., Ltd., 50% by weight solution)]: 2.25 parts by weight Photosensitizer assistant [1,4-diethoxynaphthalene]: 1 part by mass

[0214] (iii) Preparation of protective layer-forming composition (3) The components shown below were mixed in the following proportions to obtain a composition for forming a protective layer (3). Cationic polymerizable compound [3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (product name: CEL2021P, manufactured by Daicel Corporation)]: 70 parts Neopentyl glycol diglycidyl ether (product name: EX-211, manufactured by Nagase ChemteX Corporation): 20 parts 2-Ethylhexyl glycidyl ether (product name: EX-121, manufactured by Nagase ChemteX Corporation): 10 parts Photocationic polymerization initiator [product name: CPI-100 (manufactured by San-Apro Co., Ltd., 50% propylene carbonate solution)]: 4.5 parts (actual solid content: 2.25 parts) Photosensitizer [1,4-diethoxynaphthalene]: 2 parts

[0215] (iv) Preparation of protective layer-forming composition (4) The components shown below were mixed in the following proportions to obtain a composition for forming a protective layer (4). ·Pure water: 100 parts by mass Polyvinyl alcohol film (Kuraray Co., Ltd., "Kuraray Poval KL318" (product name): carboxyl group-modified polyvinyl alcohol): 3.0 parts by mass Water-soluble polyamide epoxy resin (manufactured by Sumika Chemtex Co., Ltd., "Sumirez Resin 650" (trade name), working solution with a solids concentration of 30%): 1.5 parts by mass The parts by mass of "Sumirez Resin 650" indicates the mass of the solid content.

[0216] (v) Preparation of protective layer-forming composition (5) The components shown below were mixed in the following proportions to obtain a composition for forming a protective layer (5). Multifunctional acrylate monomer [dipentaerythritol hexaacrylate (new Nakamura Chemical Co., Ltd., "NK Ester A-DPH": 50 parts Urethane acrylate polymer [Urethane acrylate (Daicel Allnex Co., Ltd., "Ebecryl 4858": 50 copies Radical polymerization initiator [2-[4-(methylthio)benzoyl]-2-(4-mol (Irgacure 907, manufactured by BASF) propane (3 parts) Solvent [methyl ethyl ketone]: 10 parts [ka]

[0217] (2) Preparation of polarizing plate with release film (Example 1a) (i) Preparation of protective layer (1) After corona treatment was performed on the polarizer surface of the laminate film with the horizontal polarizing film obtained above, the protective layer-forming composition (1) was applied using a bar coater so that the film thickness after curing would be about 0.5 μm. Next, a UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.) was used to apply the protective layer-forming composition (1) at an integrated light dose of 500 mJ / cm2 per unit film thickness. 2 The layer made of the curable composition for forming a protective layer was irradiated with ultraviolet light so that the wavelength of the curable composition for forming a protective layer was 365 nm (based on 365 nm), thereby curing the protective layer-forming composition (1), and a polarizing plate (1a) with a release film was obtained, which was made of a cured product of release film / cured resin layer / photo-alignment film / horizontal polarizing film / protective layer-forming composition.

[0218] 3. Preparation of retardation film (1) Preparation of the composition (i) Preparation of composition (2) for forming photoalignment film The photo-alignment material (weight average molecular weight: 50,000, m:n = 50:50) having the following structure was produced in accordance with the method described in JP 2021-196514 A. Two parts of the photo-alignment material were mixed with 98 parts of cyclopentanone (solvent), and the resulting mixture was stirred at 80°C for one hour to prepare a composition (2) for forming a photo-alignment film. ·Photoalignable materials: [ka]

[0219] (ii) Preparation of a composition for forming a retardation film Polymerizable liquid crystal compound (B1) and polymerizable liquid crystal compound (B2) having the structures shown below were prepared. Polymerizable liquid crystal compound (B1) was prepared in the same manner as described in JP-A-2019-003177. Polymerizable liquid crystal compound (B2) was prepared in the same manner as described in JP-A-2009-173893. Polymerizable liquid crystal compound (B1): [ka] Polymerizable liquid crystal compound (B2): [ka]

[0220] A solution was obtained by dissolving 1 mg of polymerizable liquid crystal compound (B1) in 10 mL of chloroform. The obtained solution was placed in a measurement cell with an optical path length of 1 cm, and the measurement sample was placed in a UV-visible spectrophotometer (Shimadzu Corporation, "UV-2450") to measure the absorption spectrum. The wavelength at which the maximum absorbance was obtained was read from the obtained absorption spectrum, and the maximum absorption wavelength λmax in the wavelength range of 300 to 400 nm was 356 nm.

[0221] Polymerizable liquid crystal compound (B1) and polymerizable liquid crystal compound (B2) were mixed in a mass ratio of 90:10 to obtain a mixture. To 100 parts of the obtained mixture, 0.1 parts of a leveling agent "BYK-361N" (manufactured by BM Chemie) and 3 parts of a photopolymerization initiator "Irgacure OXE-03" (manufactured by BASF Japan Ltd.) were added. Furthermore, N-methyl-2-pyrrolidone (NMP) was added to obtain a solids concentration of 13%. The mixture was stirred at 80°C for 1 hour to prepare a retardation film-forming composition.

[0222] (2) Preparation of retardation film with release film (i) Preparation of retardation film The release-treated surface of a release-treated polyethylene terephthalate film (SP-PLR382050 manufactured by Lintec Corporation) (release film) was subjected to a corona treatment once using a corona treatment device (AGF-B10 manufactured by Kasuga Electric Co., Ltd.) at an output of 0.3 kW and a treatment speed of 3 m / min, and the photoalignment film-forming composition (2) was applied using a bar coater. The resulting coating was dried at 120°C for 2 minutes and then cooled to room temperature to form a dried film. The film was then irradiated with 100 mJ of polarized ultraviolet light (313 nm standard) using a UV irradiation device (SPOT CURE SP-9 manufactured by Ushio Inc.) to obtain a photoalignment film (2). The film thickness of the photoalignment film (2) was measured using an ellipsometer M-220 manufactured by JASCO Corporation and was 100 nm.

[0223] The retardation film-forming composition was applied onto the obtained photo-alignment film (2) using a bar coater to form a coating film. This coating film was dried by heating at 120°C for 2 minutes and then cooled to room temperature to obtain a dried film. Next, a high-pressure mercury lamp ("Uniquer VB-15201BY-A" manufactured by Ushio Inc.) was used to expose the film to light at a dose of 500 mJ / cm under a nitrogen atmosphere. 2 The dried film was irradiated with ultraviolet light (365 nm standard) to form a retardation film in which the polymerizable liquid crystal compound was cured in a state of being aligned horizontally relative to the substrate surface, and a retardation film with a release film was obtained, consisting of a release film / photo-alignment film / retardation film. The thickness of the retardation film measured using a laser microscope LEXT OLS4100 manufactured by Olympus Corporation was 2.0 μm.

[0224] The retardation film with release film was corona-treated on the retardation film side, and then attached to glass using a 25 μm pressure-sensitive adhesive from Lintec Corporation. The release film was then peeled off and removed to prepare a sample for in-plane retardation measurement. The in-plane retardation values ​​were measured using a KOBRA-WR from Oji Scientific Instruments. The in-plane retardation values ​​for light with wavelengths of 450 nm, 550 nm, and 650 nm were calculated using Cauchy's dispersion formula, which was obtained from the in-plane retardation values ​​measured for light with wavelengths of 448.2 nm, 498.6 nm, 548.4 nm, 587.3 nm, 628.7 nm, and 748.6 nm. As a result, the in-plane retardation values ​​were Re(450)=122 nm, Re(550)=140 nm, and Re(650)=144 nm, and the relationship between the in-plane retardation values ​​at each wavelength was as follows: Re(450) / Re(550)=0.87 Re(650) / Re(550)=1.03 (In the formula, Re(450) represents the in-plane retardation value for light with a wavelength of 450 nm, Re(550) represents the in-plane retardation value for light with a wavelength of 550 nm, and Re(650) represents the in-plane retardation value for light with a wavelength of 650 nm.)

[0225] 4. Fabrication of Circular Polarizers (1) Preparation of polarizing plate with lamination layer The protective layer side of the polarizing plate with release film obtained above was subjected to corona treatment, and a 5 μm pressure-sensitive adhesive manufactured by Lintec Corporation was attached to obtain a polarizing plate with an attachment layer. The refractive index of the adhesive was 1.48. (2) Preparation of a circularly polarizing plate (Example 1b) Next, the retardation film side of the retardation film with the release film obtained above was subjected to corona treatment, and the polarizing plate with the laminating layer was attached to the retardation film with the laminating layer via the laminating layer to prepare a polarizer laminate (circular polarizing plate with release film) (1b) of Example 1b. The release film was peeled off to prepare a circular polarizing plate.

[0226] 5. Example 2 A polarizing plate (2a) and a polarizer laminate (circular polarizing plate) (2b) of Example 2 were produced in the same manner as in Example 1 (Examples 1a and 1b), except that the thickness of the protective layer was 1.5 μm.

[0227] 6. Example 3 A polarizing plate (3a) and a polarizer laminate (circularly polarizing plate) (3b) of Example 3 were produced in the same manner as in Example 1, except that the thickness of the protective layer was changed to 2.0 μm.

[0228] 7. Example 4 A polarizing plate (4a) and a polarizer laminate (circularly polarizing plate) (4b) of Example 4 were produced in the same manner as in Example 1, except that the thickness of the protective layer was set to 3.0 μm.

[0229] 8. Example 5 A polarizing plate (5a) and a polarizer laminate (circular polarizing plate) (5b) were prepared in the same manner as in Example 1, except that a protective layer-forming composition (2) was used instead of a protective layer-forming composition (1) as the curable composition for forming the protective layer, and the thickness of the protective layer was set to 2.0 μm.

[0230] 9. Example 6 A polarizing plate (6a) and a polarizer laminate (circular polarizing plate) (6b) were prepared in the same manner as in Example 1, except that a protective layer-forming composition (3) was used instead of a protective layer-forming composition (1) as the curable composition for forming the protective layer, and the thickness of the protective layer was set to 2.0 μm.

[0231] 10. Comparative Example 1 A polarizing plate (1x) and a polarizer laminate (circular polarizing plate) (1y) of Comparative Example 1 were each prepared in the same manner as in Example 1, except that a protective layer-forming composition (4) was used instead of a protective layer-forming composition (1) as the curable composition for forming the protective layer, and the thickness of the protective layer was set to 1.0 μm.

[0232] 11. Comparative Example 2 A polarizing plate (2x) and a polarizer laminate (circular polarizing plate) (2y) of Comparative Example 2 were prepared in the same manner as in Example 1, except that a protective layer-forming composition (5) was used instead of a protective layer-forming composition (1) as the curable composition for forming the protective layer, and the thickness of the protective layer was set to 2.0 μm.

[0233] <Curling> The occurrence of curling was evaluated using the circularly polarizing plates of Examples 1 to 6 and Comparative Examples 1 and 2. The results are shown in Table 1. (Evaluation criteria) Good: Almost no curl, or slight curl but no cylindrical shape. ×: The curl is large and rolls into a cylindrical shape.

[0234] <Water resistance> A warm water immersion test was carried out on the circularly polarizing plates of Examples 1 to 6 and Comparative Examples 1 and 2 according to the following method. First, a polarizing plate was cut into a 5 cm x 2 cm strip with the absorption axis of the circularly polarizing plate as the long side, and then attached to a glass plate via an adhesive to prepare a sample. This sample was immersed in a water bath at 60°C and held for 4 hours, after which the sample was removed from the water bath and the moisture was wiped off. Next, cellophane tape was attached to one side of the film, and the state of the sample edge when peeled off was used to evaluate the water resistance of adhesion according to the following evaluation criteria. The results are shown in Table 2. (Evaluation criteria) ◯: No peeling occurs at the film edge. ×: Partial peeling occurs at the edge of the film.

[0235] <Evaluation of ΔTy before and after forming the protective layer> The single-piece transmittance Ty was measured using the following method for a polarizing plate with a layer structure of PET / cured resin layer / photo-alignment layer / horizontal polarizing film before lamination of a protective layer, and a polarizing plate with a layer structure of PET / cured resin layer / photo-alignment layer / horizontal polarizing film / protective layer, and the change in single-piece transmittance (ΔTy) before and after formation of the protective layer was calculated. The optical properties were evaluated based on the calculated ΔTy values ​​using the evaluation criteria below. The results are shown in Table 2. Note that a small change in single-piece transmittance Ty (ΔTy) before and after formation of the protective layer indicates that dye diffusion was not occurring due to heat during curing. (Evaluation criteria) 〇: |ΔTy|<1.0 △:1.0≦|ΔTy|<5.0 ×:5.0≦|ΔTy|

[0236] <Measurement of single unit transmittance Ty> The polarizer's single transmittance was measured using a spectrophotometer equipped with an integrating sphere (JASCO Corporation, model V7100) with linearly polarized light incident from a prism on the horizontal polarizing film side. The MD and TD transmittances were determined over a wavelength range of 380 nm to 780 nm, and the single transmittance at each wavelength was calculated using formula (A). Luminosity correction was then performed using the 2-degree viewing angle (illuminant C) of JIS Z 8701 to determine the luminosity-corrected single transmittance (Ty). Note that "MD transmittance" refers to the transmittance when the direction of the polarized light exiting the Glan-Thompson prism is parallel to the transmission axis of the polarizer sample. In formula (A), "MD transmittance" is represented as "MD." Furthermore, "TD transmittance" refers to the transmittance when the direction of the polarized light exiting the Glan-Thompson prism is perpendicular to the transmission axis of the polarizer sample. In formulas (A) and (B), "TD transmittance" is represented as "TD." Single transmittance (%) = (MD + TD) / 2 Formula (A)

[0237] <Reflective appearance> The circularly polarizing plates of Examples 1 to 6 and Comparative Examples 1 and 2 were attached to a black acrylic plate with the retardation film side of the circularly polarizing plate attached via an adhesive, and the laminate was visually observed from the front under illumination by a three-band fluorescent lamp. The three-band fluorescent lamp was positioned so that it would not be reflected in the laminate. From the visual observation results, the reflective appearance was evaluated based on the following evaluation criteria. The results are shown in Table 1. (Evaluation criteria) ◯: No light reflection was observed at the interface inside the laminate, and the laminate appeared black and firm. Δ: A small amount of light reflection was visible at the interface within the laminate, making the laminate appear slightly whitish. ×: The laminate appeared whitish due to light reflection at the interface within the laminate.

[0238] <In-plane average refractive index> The prepared protective layer-forming composition was applied to one side of a stretched norbornene resin film (ZEON Corporation, Zeonor Film) using a bar coater (Daiichi Rika Co., Ltd.) so that the thickness after ultraviolet irradiation would be approximately 30 μm, and the coating was then irradiated with an ultraviolet irradiation device (Fusion UV Systems Co., Ltd.) under a nitrogen atmosphere with an integrated light dose of 600 mJ / cm. 2 The norbornene resin film was peeled off from the cured product, and the in-plane average refractive index (589 nm) of the cured product layer was measured at 25°C using a multi-wavelength Abbe refractometer (DR-M2, manufactured by Atago Co., Ltd.). For the protective layer forming composition of Comparative Example 1, the protective layer forming composition was coated using a bar coater so that the thickness after drying would be approximately 30 μm, and then placed in an oven and dried at 100°C for 10 minutes to obtain a cured product. The average in-plane refractive index of the protective layers in Examples 1 to 4 and 6 was 1.51, and the average in-plane refractive index of the protective layer in Example 5 was 1.54. The average in-plane refractive index of the protective layers in Comparative Examples 1 and 2 was 1.51 and 1.53, respectively.

[0239] [Table 1]

Claims

1. A polarizing plate including a polarizing film and a protective layer adjacent to the polarizing film, the polarizing film is configured to include a cured product of a polymerizable liquid crystal composition containing a polymerizable liquid crystal compound and a dichroic dye, and has a thickness of 0.1 to 5 μm; the protective layer is a cured product layer of a curable composition containing a cationically polymerizable compound and has a thickness of 0.2 to 5 μm; Polarizing plate.

2. The polarizing plate according to claim 1 , wherein the cationically polymerizable compound includes a polymerizable compound having a cyclic ether structure.

3. 2. The polarizing plate according to claim 1, wherein the protective layer has an in-plane average refractive index of 1.50 to 1.

55.

4. The polarizing plate according to claim 1 , wherein the polarizing film is a horizontal polarizing film.

5. The polarizing plate according to claim 1 , wherein the protective layer is an outermost layer of the polarizing plate.

6. The polarizing plate according to claim 1 , wherein the cationically polymerizable compound includes a polymerizable compound having an oxetane ring.

7. The polarizing plate according to claim 1 , further comprising a cured resin layer on the side of the polarizing film opposite to the surface adjacent to the protective layer.

8. 8. The polarizing plate according to claim 7, wherein the cured resin layer is a cured product layer of a curable resin composition containing a polyfunctional (meth)acrylate compound, and has a thickness of 0.1 to 5 μm.

9. A circularly polarizing plate in which the polarizing plate according to any one of claims 1 to 8 and a retardation film are laminated via an attachment layer, wherein the protective layer of the polarizing plate, the attachment layer, and the retardation film are adjacent to each other in this order.

10. 10. The circularly polarizing plate according to claim 9, wherein the attachment layer has a thickness of 1 to 10 μm.

11. 10. The circular polarizer according to claim 9, wherein the retardation film has a thickness of 0.1 to 5 μm.

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