Composition for forming photo-alignment films, photo-alignment films, laminates, and polarizing elements

Abstract

To provide a photoalignment film-forming composition which allows for forming a photoalignment film that features good adhesion to a base material and has improved liquid stability.SOLUTION: A photoalignment film-forming composition is provided, containing a photoalignment polymer having a photoreactive group, silane coupling agent, acid, and solvent.SELECTED DRAWING: None

Description

[Technical Field] 【0001】 The present invention relates to a composition for forming photo-alignment films, a photo-alignment film, a laminate, and a polarizing element. [Background technology] 【0002】 Polarizing elements are known that include a laminate in which a photo-alignment film and a polarizing film are laminated on a substrate, and it is known that the photo-alignment film of the polarizing element is formed by coating the substrate with a photo-alignment film forming composition containing photoreactive groups that undergo a dimerization reaction (Patent Document 1). In such laminates, attempts have been made to further improve the adhesion between the photo-alignment film and the substrate and to further suppress peeling. For example, Patent Document 2 discloses a liquid crystal alignment agent containing a photo-aligning polymer and a silane compound as a suitable liquid crystal alignment agent for phase difference films that can form a liquid crystal alignment film with good adhesion to a substrate. [Prior art documents] [Patent Documents] 【0003】 [Patent Document 1] Japanese Patent Publication No. 2017-102479 [Patent Document 2] Japanese Patent Publication No. 2014-123091 [Overview of the project] [Problems that the invention aims to solve] 【0004】 However, in the aforementioned photo-alignment film forming compositions, in addition to good adhesion between the photo-alignment film obtained from the composition and the substrate, further improvement in the liquid stability of the photo-alignment film forming composition was required. 【0005】 Therefore, the object of the present invention is to provide a photo-alignment film forming composition that can form a photo-alignment film with good adhesion to a substrate and has improved liquid stability. [Means for solving the problem] 【0006】 As a result of diligent research to solve the aforementioned problems, the present inventors have found that a photo-alignment film-forming composition comprising a photo-oriented polymer having a photoreactive group, a silane coupling agent, an acid, and a solvent can solve the aforementioned problems, and have completed the present invention. That is, the present invention includes the following preferred embodiments. 【0007】 [1] A composition for forming a photo-aligned film, comprising a photo-oriented polymer having a photoreactive group, a silane coupling agent, an acid, and a solvent. [2] The composition according to [1], wherein the photo-oriented polymer has a photoreactive group that undergoes a dimerization reaction. [3] The composition according to [1] or [2], wherein the photo-oriented polymer is a (meth)acrylic polymer. [4] The composition according to any one of [1] to [3], wherein the photo-oriented polymer further has a carboxyl group. [5] The composition according to any one of [1] to [4], wherein the weight-average molecular weight of the photo-oriented polymer is 10,000 or more and 1,000,000 or less. [6] The silane coupling agent is a composition according to any one of [1] to [5], having at least one group selected from the group consisting of a primary amino group and a secondary amino group. [7] The composition according to any one of [1] to [6], wherein the content of the silane coupling agent is 0.5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the photo-oriented polymer. [8] The composition according to any one of [1] to [7], wherein the acid comprises at least one selected from the group consisting of formic acid, toluenesulfonic acid, acrylic acid, and acetic acid. [9] The composition according to any one of [1] to [8], wherein the molar ratio of the acid to the silane coupling agent is 1 or more and 50 or less. A photo-oriented film obtained by curing any of the compositions described in

[10] , [1], to [9].

[11] A laminate comprising a substrate and the photo-alignment film described in

[10] .

[12] The laminate according to

[11] , wherein the film thickness of the substrate is 1 μm or more and 20 μm or less.

[13] A polarizing element comprising a substrate, the photo-alignment film and polarizing film described in

[10] .

[14] A polarizing element as described in

[13] , having a thickness of 1 μm or more and 10 μm or less. [Effects of the Invention] 【0008】 According to the present invention, it is possible to provide a photo-alignment film forming composition that can form a photo-alignment film with good adhesion to a substrate and has improved liquid stability. [Modes for carrying out the invention] 【0009】 The embodiments of the present invention will be described in detail below. However, the scope of the present invention is not limited to the embodiments described herein, and various modifications can be made without departing from the spirit of the invention. 【0010】 [Composition for forming photo-alignment film] The photo-alignment film-forming composition of the present invention comprises a photo-aligning polymer having a photoreactive group, a silane coupling agent, an acid, and a solvent. 【0011】 [Photo-oriented polymer] The photo-orienting polymer of the present invention has a photoreactive group. A photoreactive group is a group that generates liquid crystal alignment ability when irradiated with light (photoirradiation). Specifically, this includes groups that are involved in photoreactions that are the origin of liquid crystal alignment ability, such as orientation induction of polymer molecules or isomerization reactions, dimerization reactions, photocrosslinking reactions, or photodegradation reactions, which are generated when irradiated with light. As photoreactive groups, groups having unsaturated bonds, especially double bonds, are preferred, and groups having at least one selected from the group consisting of carbon-carbon double bonds (C=C bonds), carbon-nitrogen double bonds (C=N bonds), nitrogen-nitrogen double bonds (N=N bonds), and carbon-oxygen double bonds (C=O bonds) are preferred. The photo-orienting polymer may have one type of photoreactive group or two or more types. 【0012】 Examples of photoreactive groups having a C=C bond include vinyl groups, polyene groups, stilbene groups, stilbazole groups, stilbazolium groups, chalcone groups, and cinnamoyl groups. Examples of photoreactive groups having a C=N bond include groups having structures such as aromatic Schiff bases and aromatic hydrazones. Examples of photoreactive groups having an N=N bond include azobenzene groups, azonaphthalene groups, aromatic heterocyclic azo groups, bisazo groups, formazan groups, and groups having an azoxybenzene structure. Examples of photoreactive groups having a C=O bond include benzophenone groups, coumarin groups, anthraquinone groups, and maleimide groups. These groups may have substituents such as alkyl groups, alkoxy groups, aryl groups, allyloxy groups, cyano groups, alkoxycarbonyl groups, hydroxyl groups, sulfonic acid groups, and halogenated alkyl groups. In particular, from the viewpoint of excellent orientation and responsiveness, photo-oriented polymers are preferably those having photoreactive groups that undergo dimerization reactions or photocrosslinking reactions, and more preferably those having photoreactive groups that undergo dimerization reactions. 【0013】 A dimerization reaction is a reaction in which an addition reaction occurs between two groups due to the action of light, typically forming a ring structure. Groups that undergo such dimerization reactions include groups containing a carbon-carbon double bond (C=C bond) or a carbon-oxygen double bond (C=O bond) that triggers a dimerization reaction upon light irradiation. Examples include groups having a cinnamoyl structure, a chalcone structure, a coumarin structure, a benzophenone structure, and an anthracene structure. Among these, groups having a cinnamoyl structure and a chalcone structure are preferred, with groups having a cinnamoyl structure being more preferred, because their reactivity is easy to control and they exhibit excellent orientation-regulating power during photo-alignment. Furthermore, groups having the above structures are advantageous because they require a relatively small amount of polarized irradiation for photo-alignment, and it is easy to obtain photo-alignment films with excellent thermal stability and chronological stability. 【0014】 In the present invention, in order to easily form a photo-alignment film with good adhesion to the substrate and to easily obtain a photo-alignment film composition having improved liquid stability, it is preferable that the photo-aligning polymer has a photoreactive group that undergoes a dimerization reaction at the end of the polymer side chain, more preferably a group having a cinnamoyl structure or a chalcone structure at the end of the polymer side chain, and even more preferably a group having a cinnamoyl structure at the end of the polymer side chain. Examples of such photo-aligning polymers include polymers having a structure represented by the following formula (A1') and / or a structure represented by formula (A1'') in their side chains (hereinafter, these are collectively referred to as "photo-aligning polymer (A)"). 【0015】 [ka] [In formulas (A1') and (A1''), k represents either 0 or 1. L 1 represents a single bond or -O-. L 2 The '-' represents a single bond, -O-, -COO-, -OCO-, -N=N-, -CH=CH-, or -CH2-. R 1 , R 2 and R 3 Each of these independently represents a hydrogen atom, a halogen atom, a halogenated alkyl group, a halogenated alkoxy group, a cyano group, a nitro group, an alkyl group, an alkoxy group, an aryl group, an allyloxy group, an alkoxycarbonyl group, a carboxyl group, a sulfonic acid group, an amino group, or a hydroxyl group, wherein the carboxyl group and the sulfonic acid group may form salts with alkali metal ions. R 4 represents a hydrogen atom, an alkyl group, or a phenyl group. * represents a bond to the polymer backbone. 【0016】 In equations (A1') and (A1''), L 2When it is any one of a single bond, -O-, -COO-, -OCO-, -N=N-, -C=C- and -CH2-, the production of the photo-aligning polymer (A) becomes easy. 【0017】 In formula (A1') and formula (A1''), R 1 , R 2 and R 3 are each independently preferably an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms because it is easy to form a photo-alignment film having good adhesion to the substrate and it is easy to obtain a composition for a photo-alignment film having improved liquid stability. The alkyl groups represented by R 1 , R 2 and R 3 include a methyl group, an ethyl group, a butyl group, etc., and the alkoxy groups include a methoxy group, an ethoxy group, a butoxy group, etc. 【0018】 The main chain of the photo-aligning polymer (A) is not particularly limited. As the structure of the monomer unit forming the main chain, for example, (meth)acrylate units represented by formula (M-1) or formula (M-2); (meth)acrylamide units represented by formula (M-3) or formula (M-4); vinyl ether units represented by formula (M-5) or formula (M-6); methylstyrene units represented by formula (M-7) or formula (M-8), and vinyl ester units represented by formula (M-9) or formula (M-10) are included. In formulas (M-1) to (M-10), * represents a bond to the structure represented by formula (A1') or formula (A''), or a bond to a spacer unit described later. In the present specification, the "main chain of the photo-aligning polymer (A)" refers to the longest molecular chain among the molecular chains possessed by the photo-aligning polymer (A). 【0019】 【Chemical formula】 【0020】 The main chain of the photo-oriented polymer (A) may be a homopolymer formed from one type of monomer unit, or a copolymer formed from two or more types of monomer units. If the main chain of the photo-oriented polymer (A) is a copolymer, it may be an alternating, block, random, or graft-type bond. 【0021】 Furthermore, the structure of the monomer units forming the main chain of the photo-oriented polymer (A) may be a silocethsiloxane structure containing repeating units represented by the following formulas (M-11) to (M-16). In formulas (M-11) to (M-16), * represents a bond with the structure represented by formula (A1') or formula (A1''), or a bond with the spacer unit described later. 【0022】 [ka] 【0023】 In formulas (M-11) to (M-16), R 5 R indicates that the silicon atom is bonded to an alkyl group with 1 to 6 carbon atoms, an alkoxy group with 1 to 6 carbon atoms, or via an oxygen atom. 5 Examples of C1-C6 alkyl groups represented by include methyl, ethyl, n-propyl, isopropyl, and n-butyl groups, with methyl and ethyl groups being preferred. 5 Examples of alkoxy groups having 1 to 6 carbon atoms represented by include methoxy, ethoxy, n-propyloxy, isopropyloxy, and n-butoxy groups, with methoxy and ethoxy groups being preferred. 【0024】 In formulas (M-13) and (M-14), Ph represents a optionally substituted divalent benzene ring (e.g., a phenylene group). In formula (M-16), Cy represents an optionally substituted divalent cyclohexane ring (e.g., a cyclohexane-1,4-diyl group). n represents an integer between 1 and 4. 【0025】 In particular, the main chain of the photo-oriented polymer (A) is preferably composed of structural units represented by any of formulas (M-1) to (M-16), more preferably composed of structural units represented by any of formulas (M-1) to (M-10), and even more preferably composed of structural units selected from the group consisting of (meth)acrylic acid ester units and (meth)acrylamide units represented by formulas (M-1) to (M-4), because it is easy to form a photo-oriented film with good adhesion to the substrate and easy to obtain a photo-oriented film composition with good liquid stability. Furthermore, a polymer in which the proportion of structural units selected from the group consisting of (meth)acrylic acid ester units and (meth)acrylamide units is the largest among all structural units constituting the main chain is sometimes referred to as a "(meth)acrylic polymer." In other words, the photo-oriented polymer in the present invention is preferably a (meth)acrylic polymer. 【0026】 The monomer structural units forming the main chain of the photo-oriented polymer (A), such as those represented by any of formulas (M-1) to (M-16), may be directly bonded to a group represented by formula (A1') or formula (A1''), or they may be bonded via a linking group, which is a suitable spacer unit. When bonded via a linking group, examples of linking groups include carbonyloxy groups (ester bonds), oxygen atoms (ether bonds), imide groups, carbonylimino groups (amide bonds), iminocarbonylimino groups (urethane bonds), optionally substituted divalent aliphatic hydrocarbon groups and optionally substituted divalent aromatic hydrocarbon groups, and divalent groups formed by combinations thereof. Specific examples of divalent aromatic hydrocarbon groups that may have substituents include phenylene, 2-methoxy-1,4-phenylene, 3-methoxy-1,4-phenylene, 2-ethoxy-1,4-phenylene, 3-ethoxy-1,4-phenylene, and 2,3,5-trimethoxy-1,4-phenylene. Among these, the linking group is preferably an aliphatic hydrocarbon group, and more preferably an alkanediyl group having 1 to 11 carbon atoms that may have substituents. Examples of such alkanediyl groups include methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, and undecamethylene, and these may be linear or branched. Furthermore, such alkanediyl groups may have substituents. These substituents are, for example, alkoxy groups having 1 to 4 carbon atoms. 【0027】 The structure represented by formula (A1') preferably constitutes the photo-oriented polymer (A) as a structural unit represented by formula (A1-1) (hereinafter sometimes referred to as "structural unit (A1-1)'"), and in one embodiment of the present invention, the photo-oriented polymer (A) includes structural unit (A1-1). Furthermore, the structure represented by formula (A1'') preferably constitutes the photo-oriented polymer (A) as a structural unit represented by formula (A1-2) (hereinafter also referred to as "structural unit (A1-2)''"), and in one embodiment of the present invention, the photo-oriented polymer (A) includes structural unit (A1-2). 【0028】 [ka] 【0029】 In equations (A1-1) and (A1-2), L 1 , L 2 , R 1 , R 2 , R 3 , R 4 and k are equivalent to those in formula (A1') or formula (A1''), respectively, SP 1 M is an alkanediyl group having 1 to 11 carbon atoms, which may have substituents. 1 The structure represented by is the structure represented by any of the equations (M-1) to (M-16). 【0030】 The photo-oriented polymer (A) may have carboxyl groups in addition to photoreactive groups, particularly photoreactive groups that undergo dimerization reactions. One embodiment of the photo-oriented polymer (A) having photoreactive groups and carboxyl groups may be a polymer consisting of structural units (A1-1), and another embodiment may be composed of, for example, a structure represented by formula (A1'), a structure represented by formula (A''), or structural units (A1-1) and / or structural units (A1-2), in addition to a structural unit represented by formula (A1-3) (hereinafter also referred to as "structural unit (A1-3)"). [ka] 【0031】 In equation (A1-3), l represents 0 or 1, SP 2 SP represents an alkanediyl group having 1 to 11 carbon atoms, which may have substituents. 2 A concrete example is SP in equations (A1-1) and (A1-2). 1 This is the same as the specific example, M 2 The structure represented by is the structure represented by any of the equations (M-1) to (M-16). 【0032】 In formula (A1-3), L 3 represents a single bond or -O-, and L 4 represents a single bond, -O-, -COO-, -OCO-, -N=N-, -CH=CH- or -CH2-. R 6 and R 7 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. Examples of the alkyl group represented by R 6 and R 7 include a methyl group, an ethyl group and a butyl group, and examples of the alkoxy group include a methoxy group, an ethoxy group and a butoxy group. 【0033】 When the photoalignable polymer (A) contains the structural unit (A1-1) or the structural unit (A1-2) and the structural unit (A1-3), when the molar fractions of the structural unit (A1-1), the structural unit (A1-2) and the structural unit (A1-3) with respect to all the structural units constituting the photoalignable polymer (A) are p, q and r, respectively (where p + r = 1 and q + r = 1), it is preferable to satisfy the relationships of 0.10 < p or q ≤ 0.90 and 0.10 ≤ r < 0.90. In the photoalignable polymer composed of the structural unit (A1-1), the structural unit (A1-1) may be one kind or two or more kinds. Further, the photoalignable polymer (A) may have structural units other than the structural unit (A1-1), (A1-2) and the structural unit (A1-3) (hereinafter sometimes referred to as "other structural units") as long as the alignment ability by light irradiation is not significantly impaired. 【0034】 The photoalignable polymer (A) can be produced by (co)polymerizing a monomer that induces the structural unit (A1-1) or the structural unit (A1-2) and, if necessary, a monomer that induces the structural unit (A1-3) and / or other structural units. As the method of (co)polymerization, a method conventionally known in the art may be adopted. For example, chain polymerizations such as radical polymerization, anionic polymerization and cationic polymerization, and addition polymerization methods such as coordination polymerization can be adopted. The polymerization conditions can be appropriately determined according to the type and amount of the monomers used so as to obtain the photoalignable polymer (A) having a desired molecular weight. 【0035】 The weight-average molecular weight (Mw) of the photo-oriented polymer (A) is preferably 10,000 or more, more preferably 15,000 or more, even more preferably 20,000 or more, preferably 1,000,000 or less, more preferably 500,000 or less, and even more preferably 250,000 or less. When the weight-average molecular weight of the photo-oriented polymer (A) is above the lower limit, it is easier to form a photo-oriented film with good adhesion to the substrate, and when the weight-average molecular weight is below the upper limit, the photo-oriented film tends to be easier to handle. The weight-average molecular weight can be adjusted to be above the lower limit and below the upper limit by appropriately adjusting, for example, the type of constituent units of the photo-oriented polymer (A); the reaction temperature and / or reaction time when synthesizing the photo-oriented polymer (A); etc. The weight-average molecular weight of the photo-oriented polymer (A) can be determined, for example, by performing gel permeation chromatography (GPC) measurement and converting it to standard polystyrene. 【0036】 In the photo-alignment film-forming composition, polymer (A) may be used alone or in combination of two or more types. 【0037】 The content of the photo-aligning polymer in the photo-alignment film-forming composition is not particularly limited as long as the concentration allows the photo-aligning polymer to be completely dissolved in the solvent. However, it is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, preferably 20% by mass or less, and more preferably 10% by mass or less, relative to the total mass of the photo-alignment film-forming composition. When the concentration of the photo-aligning polymer is above the lower limit, the resulting alignment film tends not to become too thin, and adhesion to the substrate tends to improve. Also, when the concentration of the photo-aligning polymer is below the upper limit, the viscosity of the composition decreases, and unevenness in the thickness of the coating film of the composition tends to occur less easily. Note that if the photo-alignment film-forming composition contains two or more types of photo-aligning polymers, the above content refers to the total amount of the two or more types of photo-aligning polymers. 【0038】 [Silane coupling agent] In the present invention, the silane coupling agent can be any compound known in the art. Specifically, examples include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, and 3-glycidoxypropylethoxydimethylsilane. 【0039】 Furthermore, the silane coupling agent may be of the silicone oligomer type. When the silicone oligomer is expressed in the form of a (monomer) oligomer, examples include mercaptopropyl group-containing copolymers such as 3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymer, and 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymer; and mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltriethoxysilane-tetraethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer. Copolymers containing a 3-glycidoxypropyl group; such as 3-glycidoxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-glycidoxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-glycidoxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-glycidoxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-glycidoxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-glycidoxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-glycidoxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, 3-glycidoxypropylmethyldiethoxysilane-tetraethoxysilane copolymer, etc.3-Methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-Methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-Methacryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-Methacryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-Methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-Methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer Methacryloyloxypropyl group-containing copolymers such as xysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer; 3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, and 3-acryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer Acryloyloxypropyl group-containing copolymers such as 3-acryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer; vinyl trimethoxy Vinyl group-containing copolymers such as sisilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer;Examples of amino group-containing copolymers include 3-aminopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-aminopropylmethyldiethoxysilane-tetraethoxysilane copolymer. The silane coupling agent may be used alone or in combination of two or more types. 【0040】 Among the silane coupling agents described above, in the present invention, a silane coupling agent having at least one functional group selected from the group consisting of primary amino groups, secondary amino groups, and mercapto groups is preferred, and a silane coupling agent having at least one functional group selected from the group consisting of primary amino groups and secondary amino groups is more preferred. By having at least one functional group selected from the group consisting of the aforementioned functional groups, the silane coupling agent is likely to form a photo-alignment film with good adhesion to the substrate and to be a photo-alignment film-forming composition with improved liquid stability. The functional group may have substituents or protecting groups as appropriate to control the reactivity of the silane coupling agent. Examples of silane coupling agents having protecting groups include KBE-9103P (ketimine type) and X-12-1172ES (aldimine type) manufactured by Shin-Etsu Chemical Co., Ltd. as amino group-protected types, and X-12-1056ES as a mercapto group-protected type. 【0041】 Among the silane coupling agents mentioned above, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, and N-phenyl-3-aminopropyltrimethoxysilane are preferred because they readily form photo-aligned films with better adhesion to the substrate. Commercially available compounds can also be used as such silane coupling agents, for example, KBE-903, KBM-602, KBM-603, KBM-903, KBE-9103P, and KBM-573 (manufactured by Shin-Etsu Chemical Co., Ltd.). 【0042】 The silane coupling agent is preferably contained in the photo-alignment film-forming composition in an amount of 0.5 parts by mass or more, more preferably 1 part by mass or more, even more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more, preferably 30 parts by mass or less, more preferably 25 parts by mass or less, and even more preferably 14 parts by mass or less, per 100 parts by mass of the photo-aligning polymer. If the content of the silane coupling agent is above the lower limit, the photo-alignment film-forming composition tends to form a photo-alignment film with good adhesion to the substrate and tends to have improved liquid stability. If the content of the silane coupling agent is below the upper limit, the orientation of the aligning film formed from the photo-alignment film-forming composition tends to be good after storage of the photo-alignment film-forming composition. 【0043】 [acid] In the present invention, the photo-alignment film-forming composition contains an acid. The acid contributes particularly to improving the liquid stability of the photo-alignment film-forming composition. In the present invention, the acid may be an organic acid or an inorganic acid. Examples of inorganic acids include acids derived from hydrogen halides (e.g., hydrochloric acid, hydrobromic acid, etc.), acids derived from halogen oxoacids (e.g., hypochlorous acid, chlorous acid, perchloric acid, hypobromous acid, bromous acid, perbromic acid, etc.), sulfuric acid, nitric acid, phosphoric acid, hexafluorophosphate, chromic acid, boric acid, etc. Examples of organic acids include glycolic acid, carboxylic acids (acetic acid, citric acid, formic acid, gluconic acid, lactic acid, oxalic acid, tartaric acid, etc.), sulfonic acids (methanesulfonic acid, ethanesulfonic acid, benzenesulfonic acid, toluenesulfonic acid, etc.), acrylic acid, methacrylic acid, etc. One type of acid may be used alone, or two or more types may be used in combination. 【0044】 In a preferred embodiment of the present invention, the acid preferably has an acid dissociation constant (pKa) of 5.0 or less, more preferably 4.5 or less, and even more preferably 4.0 or less. When the pKa of the acid is below the above upper limit, it is easier to form a photo-alignment film with good adhesion to the substrate, and the photo-alignment film forming composition tends to have improved liquid stability. The lower limit of the pKa is not particularly limited, but is preferably -5.0 or more, more preferably -4.0 or more, and even more preferably -3.0 or more. When the pKa of the acid is above the above lower limit, it is easier to suppress acid corrosion of manufacturing equipment. The pKa of the acid can be obtained from materials such as the "Chemical Handbook" (The Chemical Society of Japan). When the photo-alignment film forming composition contains two or more acids, it is preferable that at least one of them satisfies the above pKa. 【0045】 In the present invention, the boiling point of the acid is preferably 70°C or higher, more preferably 80°C or higher, even more preferably 90°C or higher, preferably 150°C or lower, and more preferably 140°C or lower. If the boiling point of the acid is above the lower limit, it is easier to form a photo-alignment film with good adhesion to the substrate and the photo-alignment film forming composition is likely to have improved liquid stability. If the boiling point of the acid is below the upper limit, it is easier to reduce the amount of residual acid in the photo-alignment film. The boiling points of acids can be obtained from materials such as the "Chemical Handbook" (The Chemical Society of Japan). If the photo-alignment film forming composition contains two or more acids, it is preferable that at least one of them satisfies the above boiling point. 【0046】 A preferred example of the acid in the present invention is that it readily forms a photo-alignment film with good adhesion to the substrate and has improved liquid stability, and therefore preferably contains at least one selected from the group consisting of formic acid, toluenesulfonic acid, acrylic acid, and acetic acid. 【0047】 In the present invention, the molar ratio of the acid to the silane coupling agent (acid [moles] / silane coupling agent [moles]) is preferably 1 or more, more preferably 2 or more, even more preferably 6 or more, even more preferably 15 or more, preferably 100 or less, more preferably 60 or less, and even more preferably 50 or less. When the molar ratio of the acid to the silane coupling agent is above the lower limit, it is easy to form a photo-alignment film with good adhesion to the substrate and the photo-alignment film forming composition tends to have improved liquid stability. Furthermore, the orientation of the alignment film formed from the photo-alignment film forming composition tends to be good. When the molar ratio of the acid to the silane coupling agent is below the upper limit, it is easy to reduce the amount of residual acid in the photo-alignment film. 【0048】 Our investigations have shown that adding a specific acid, particularly an acid with a specific pKa, to a photo-alignment film-forming composition containing a photo-aligning polymer, a silane coupling agent, and a solvent makes it easier to improve the liquid stability of the conventional photo-alignment film-forming composition. Although the reason for this is not clear, it is presumed that adding a specific acid enhances the suppression effect of side reactions in the composition that impair the liquid stability of the photo-alignment film-forming composition. 【0049】 [solvent] In the photo-alignment film-forming composition of the present invention, the solvent is not particularly limited as long as it is a solvent that can dissolve the components contained in the photo-alignment film-forming composition. Specifically, examples include water; alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene; nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; and chlorine-substituted hydrocarbon solvents such as chloroform and chlorobenzene. These solvents may be used individually or in combination of two or more. 【0050】 [Other ingredients] In the present invention, the photo-alignment film forming composition may contain any components other than those described above, as long as the properties of the photo-alignment film are not significantly impaired. Examples of such optional components include polymer materials and photosensitizers. 【0051】 The solution properties of the photo-alignment film-forming composition can be improved by using polymer materials. Examples of such polymer materials include polyvinyl alcohol, polyimide, and cellulose derivatives. One polymer material may be used alone, or two or more may be used in combination. The content of the polymer material in the photo-alignment film-forming composition (total amount if multiple types are included) is usually 0.1 to 10 parts by mass, preferably 1 to 8 parts by mass, per 100 parts by mass of the photo-aligning polymer. When the content of the polymer material is within the above range, a composition with excellent coatability can be obtained. 【0052】 Photosensitizers can improve the film strength of photo-aligned films. Examples of photosensitizers include xanthone compounds such as xanthone or thioxanthone (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.), anthracene compounds having substituents such as anthracene or alkyl ether (e.g., dibutoxyanthracene, etc.), phenothiazine, or rubrene. Photosensitizers may be used individually or in combination of two or more. 【0053】 When the photo-alignment film-forming composition contains a photosensitizer, its content (total amount if multiple types are included) is preferably 0.1 to 30 parts by mass, more preferably 0.3 to 10 parts by mass, and even more preferably 0.5 to 8.0 parts by mass, per 100 parts by mass of the photo-aligning polymer. When the photosensitizer content is within the above range, a composition with improved film strength can be obtained. 【0054】 The photo-alignment film-forming composition can be manufactured by conventionally known preparation methods, and can usually be prepared by mixing and stirring the above-mentioned components. 【0055】 The viscosity of the photo-alignment film-forming composition is preferably 0.1 to 50 mPa·s, more preferably 0.5 to 40 mPa·s, and even more preferably 1 to 30 mPa·s. When the viscosity of the photo-alignment film-forming composition is within the above range, the composition has excellent handling and coating properties, and it is easy to achieve a uniform thickness in the resulting photo-alignment film. 【0056】 [Photoalignment film] The present invention encompasses a photo-alignment film, which is a cured product of the photo-alignment film-forming composition of the present invention, and a laminate comprising the photo-alignment film and a substrate. In the present invention, the photo-alignment film can be obtained, for example, by applying the photo-alignment film-forming composition to a surface on which the photo-alignment film is to be formed, such as a substrate, drying the solvent, and then irradiating it with polarized light (preferably polarized UV). In the present invention, the photo-alignment film and the substrate may be laminated with other layers (e.g., a primer layer) in between, but in one aspect of the present invention, it is preferable that the photo-alignment film and the substrate are adjacent to each other. 【0057】 In the present invention, it is preferable that the substrate has polar groups. Here, in this specification, it means that polar groups are present in the substrate before the orientation film is formed on the substrate. Examples of polar groups include hydroxyl groups, carboxyl groups, and amino groups. Among these, it is preferable that the substrate has at least one polar group selected from the group consisting of hydroxyl groups, carboxyl groups, and amino groups, and it is more preferable that it has hydroxyl groups, from the viewpoint of being easy to introduce into the substrate surface by surface modification treatment of the substrate or other means, and reactivity with the silane coupling agent. By having the polar groups in the substrate before the orientation film is formed, bonds are formed from the reaction between the polar groups present in the substrate and the silicon present in the silane coupling agent that forms the orientation film, and adhesion between the substrate and the orientation film tends to be good. Therefore, in one embodiment of the present invention, Si-O bonds may exist between the substrate and the orientation film constituting the laminate of the present invention, originating from the reaction between the polar groups (present in the substrate) and the silicon (present in the silane coupling agent). 【0058】 It is preferable that the polar groups are present on the substrate surface on the side to which the alignment film is laminated. Such a substrate may be obtained by using a resin having polar groups, such as a vinyl alcohol resin or a cellulose resin, as the material and forming a film of these resins. Alternatively, a material having precursor groups of polar groups may be formed into a film (precursor film), and then the precursor groups contained in the precursor film may be modified into polar groups. Examples of such modification include plasma treatment under vacuum or atmospheric pressure, laser treatment, ozone treatment, saponification treatment, or flame treatment. Furthermore, the substrate may be one on which a polymer having polar groups is attached to the surface of a substrate made of a material that does not have polar groups or their precursor groups, or a substrate on which a polymer having precursor groups of polar groups is attached and then modified into polar groups. In addition, it may be obtained by a method of graft polymerization in which a monomer having polar groups or a polymer having polar groups is attached to the surface of a substrate made of a material that does not have polar groups or their precursor groups, and then reacted by irradiation with radiation, plasma, ultraviolet light, etc. Methods for attaching a polymer or monomer having a polar group or a precursor group of a polar group to a substrate surface include, for example, applying a solution of the polymer or monomer dissolved in it to the substrate surface. 【0059】 The above-described substrate may undergo known pretreatment on the side on which the alignment film is laminated, either before or after the modification treatment and the treatment of attaching a polymer or monomer having polar groups or precursors of polar groups to the substrate surface, in order to further improve the adhesion between the substrate surface and the alignment film. Examples of such pretreatments include corona treatment, plasma treatment, flame treatment, and primer treatment. The specific methods and conditions for each treatment can be appropriately selected from methods and conditions known in the art, depending on the desired application or characteristics of the laminate. 【0060】 The film thickness of the substrate is preferably 1 μm or more, more preferably 1.5 μm or more, preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. When the film thickness of the substrate is above the lower limit, it tends to have excellent processability, and when the film thickness of the substrate is below the upper limit, it is easier to achieve thin film formation of the laminate. The film thickness of the substrate can be measured using, for example, a laser microscope or a stylus-type film thickness gauge. 【0061】 In the present invention, the laminate can be obtained, for example, by a method comprising applying the photo-alignment film-forming composition of the present invention onto a substrate, removing the solvent contained in the composition, and curing the photo-alignment film-forming composition from which the solvent has been removed. 【0062】 Methods for applying the photo-alignment film-forming composition onto a substrate include known methods such as spin coating, extrusion, gravure coating, die coating, bar coating, and applicator coating, as well as printing methods such as flexographic coating. 【0063】 Methods for drying and removing the solvent include natural drying, forced-air drying, heat drying, and reduced-pressure drying. This forms a dried coating film. The drying temperature may be, for example, 50 to 200°C, preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, and also preferably 150°C or lower. When the drying temperature is within the above range, the solvent can be removed efficiently. In addition, the effect of temperature on the photo-alignment film can be suppressed, making it less likely for the liquid crystal alignment ability exhibited by the photo-alignment film to decrease. The drying time is preferably 20 seconds to 10 minutes, more preferably 30 seconds to 5 minutes. 【0064】 Methods for curing the photo-alignment film-forming composition include, for example, polarized irradiation (preferably polarized UV irradiation). The direction of the alignment restricting force of the photo-alignment film can be arbitrarily controlled by selecting the polarization direction of the irradiated polarized light. 【0065】 The method of irradiating with polarized light may involve directly irradiating the dried coating film, which is obtained by removing the solvent from the photo-alignment film-forming composition, with polarized light, or by irradiating with polarized light from the side of the substrate on which the dried coating film is formed, and allowing the polarized light to pass through. Furthermore, it is particularly preferable that the polarized light is substantially parallel light. The wavelength of the polarized light to be irradiated should be in a wavelength range in which the photoreactive groups of the photo-alignment film-forming polymer can absorb light energy. Specifically, UV (ultraviolet light) in the wavelength range of 250 to 400 nm is particularly preferred. 【0066】 Examples of light sources used for polarization irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF, with high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps being more preferred. These lamps are preferred because they have a high emission intensity of ultraviolet light at a wavelength of 313 nm. Polarization can be irradiated by passing light from the light source through a suitable polarizer. Examples of polarizers that can be used include polarizing filters, polarizing prisms such as Grant-Thomson and Grant-Taylor, and wire grid type polarizers. 【0067】 In the present invention, the thickness (film thickness) of the photo-alignment film is preferably 10 nm or more, more preferably 20 nm or more, preferably 1000 nm or less, and more preferably 500 nm or less. If the thickness of the photo-alignment film is above the lower limit, sufficient alignment control force cannot be obtained, and if the thickness of the photo-alignment film is below the upper limit, thinning becomes possible. The thickness of the photo-alignment film can be measured using, for example, a laser microscope or a stylus-type film thickness gauge. 【0068】 The present invention further encompasses a polarizing element including a substrate, the photo-alignment film of the present invention, and a polarizing film. 【0069】 In the present invention, the polarizing film is not particularly limited, but examples include films in which polarizing absorption selectivity is imparted by aligning iodine or a dichroic dye in a polyvinyl alcohol (PVA) resin or an oriented liquid crystal. 【0070】 Iodine-pVA polarizing films can be produced, for example, by a sequential stretching method in which a film of PVA is stretched while heated, followed by iodine staining and crosslinking with boric acid, or by a simultaneous stretching method in which a film of PVA is stretched while undergoing iodine staining and crosslinking with boric acid in water. The stretching ratio in this case is preferably 4 to 8 times, and the film is produced by continuously immersing it in an iodine aqueous solution and a boric acid aqueous solution to impregnate the PVA film with each molecule. After staining, the PVA film is dried to remove moisture and allow boric acid crosslinking to proceed, thereby obtaining a PVA polarizing film. The drying method in this case is preferably air drying or infrared drying, and the temperature is preferably in the range of 40°C to 150°C, more preferably 60°C to 130°C. 【0071】 A polarizing film in which a dichroic dye is oriented in a liquid crystal can be fabricated, for example, by pre-mixing the dichroic dye into a layer consisting of a polymer in the oriented state of a polymerizable liquid crystal compound. 【0072】 Examples of polymerizable liquid crystal compounds include the compound represented by the following formula (I) (hereinafter sometimes referred to as "compound (I)"). These polymerizable liquid crystal compounds may be used individually or in combination of two or more types. U 1 -V 1 -W 1 -X 1 -Y 1 -X 2 -Y 2 -X 3 -W 2 -V A -U 2 (I) [In formula (I), X 1 , X 2 and X 3Each of these independently represents a divalent aromatic group or a divalent alicyclic hydrocarbon group, where the hydrogen atoms in the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with halogen atoms, C1-C4 alkyl groups, C1-C4 fluoroalkyl groups, C1-C4 alkoxy groups, cyano groups, or nitro groups, and the carbon atoms constituting the divalent aromatic group or divalent alicyclic hydrocarbon group may be substituted with oxygen atoms, sulfur atoms, or nitrogen atoms. However, X 1 , X 2 and X 3 At least one of these is a optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group. Y 1 , Y 2 , W 1 and W 2 These are, independently of each other, single or divalent linking groups. V 1 and V 2 Each of these independently represents an alkanediyl group having 1 to 20 carbon atoms, which may have substituents, and the -CH2- constituting the alkanediyl group may be replaced with -O-, -S-, or -NH-. U 1 and U 2 Each of these independently represents a polymerizable group or a hydrogen atom, and at least one of them is a polymerizable group. 【0073】 In compound (I), X 1 , X 2 and X 3 At least one of these is an optionally substituted 1,4-phenylene group or an optionally substituted cyclohexane-1,4-diyl group. In particular, X 1 and X 3Preferably, the group is a substituted cyclohexane-1,4-diyl group, and more preferably, the cyclohexane-1,4-diyl group is a trans-cyclohexane-1,4-diyl group. When the structure includes a trans-cyclohexane-1,4-diyl group, smectic liquid crystallinity tends to be easily exhibited. Optional substituents on the substituted 1,4-phenylene group or the substituted cyclohexane-1,4-diyl group include C1-C4 alkyl groups such as methyl, ethyl, and butyl groups, cyano groups, and halogen atoms such as chlorine and fluorine atoms. Preferably, the group is unsubstituted. 【0074】 Y 1 and Y 2 These are independent of each other: single bonds, -CH2CH2-, -CH2O-, -COO-, -OCO-, -N=N-, -CR a =CR b -, -C≡C- or -CR a =N- is preferred, R a and R b Each of these independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. 1 and Y 2 It is more preferably -CH2CH2-, -COO-, -OCO- or a single bond, Y 1 and Y 2 It is more preferable that the two are different coupling methods. 1 and Y 2 When the bonding methods are different from each other, smectic liquid crystal properties tend to be more likely to occur. 【0075】 W 1 and W 2 The bonds are preferably single bonds, -O-, -S-, -COO-, or -OCO-, and more preferably single bonds or -O-, independently of each other. 【0076】 V 1 and V 2Examples of C1-C20 alkanediyl groups represented by include methylene, ethylene, propane-1,3-diyl, butane-1,3-diyl, butane-1,4-diyl, pentane-1,5-diyl, hexane-1,6-diyl, heptane-1,7-diyl, octane-1,8-diyl, decane-1,10-diyl, tetradecane-1,14-diyl, and eicosan-1,20-diyl. 1 and V 2 The group is preferably an alkanediyl group having 2 to 12 carbon atoms, and more preferably a linear alkanediyl group having 6 to 12 carbon atoms. Using a linear alkanediyl group having 6 to 12 carbon atoms improves crystallinity and tends to easily exhibit smectic liquid crystal properties. The substituents that may be optionally present on an alkanediyl group having 1 to 20 carbon atoms include cyano groups and halogen atoms such as chlorine and fluorine atoms, but the alkanediyl group is preferably unsubstituted, and more preferably unsubstituted and linear. 【0077】 U 1 and U 2 Preferably, both are polymerizable groups, and more preferably, both are photopolymerizable groups. Polymerizable liquid crystal compounds having photopolymerizable groups are advantageous in that they can be polymerized under lower temperature conditions. 【0078】 U 1 and U 2 The polymerizable groups represented by may be different from each other, but are preferably the same. Examples of polymerizable groups include vinyl group, vinyloxy group, 1-chlorovinyl group, isopropenyl group, 4-vinylphenyl group, acryloyloxy group, methacryloyloxy group, oxyranil group, and oxetanil group. Among these, acryloyloxy group, methacryloyloxy group, vinyloxy group, oxyranil group, and oxetanil group are preferred, and acryloyloxy group is more preferred. 【0079】 Specific examples of the nematic liquid crystal compound (I) are described in, for example, JP-A-2017-167517, and can be produced by known methods described in, for example, Lub et al., Recl. Trav. Chim. Pays-Bas, 115, 321-328 (1996), or Japanese Patent No. 4719156. 【0080】 A dichroic dye means a dye having the property that the absorbance in the long axis direction of the molecule is different from the absorbance in the short axis direction. The dichroic dye that can be used in the present invention is not particularly limited as long as it has the above property, and may be a dye or a pigment. Further, two or more dyes or pigments may be used in combination, or a dye and a pigment may be used in combination. Further, the dichroic dye may have polymerizability or may have liquid crystallinity. 【0081】 In one embodiment of the present invention, the dichroic dye preferably has a maximum absorption wavelength (λ MAX ) in the range of 300 to 700 nm. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes. Among them, azo dyes are suitable for producing a polarizing film having excellent polarization performance because of their high linearity. Therefore, in one embodiment of the present invention, the dichroic dye is preferably an azo dye. 【0082】 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. Examples of such azo dyes include compounds represented by formula (II). K 1 (-N=N-K 2 ) p -N=N-K 3 (II) [In formula (II), K 1 and K 3 each independently represent a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or a monovalent heterocyclic group which may have a substituent. K 2represents a p-phenylene group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent, or a divalent heterocyclic group which may have a substituent. p represents an integer of 1 to 4. When p is an integer of 2 or more, a plurality of K 2 may be the same as or different from each other. In the range showing absorption in the visible region, the -N=N- bond may be replaced by a -C=C-, -COO-, -NHCO-, or -N=CH- bond.] 【0083】 In formula (II), examples of the monovalent heterocyclic group include groups obtained by removing one hydrogen atom from heterocyclic compounds such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, and benzoxazole. Examples of the divalent heterocyclic group include groups obtained by removing two hydrogen atoms from the heterocyclic compounds. 【0084】 K in formula (II) 1 and K 3 For the phenyl group, naphthyl group, and monovalent heterocyclic group in, and the substituents optionally possessed by the p-phenylene group, naphthalene-1,4-diyl group, and divalent heterocyclic group in K 2 include an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms and having a polymerizable group, 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; a cyano group; a nitro group; a halogen atom; a substituted or unsubstituted amino group such as an amino group, a diethylamino group, or a pyrrolidino group (a substituted amino group means an amino group having one or two alkyl groups having 1 to 6 carbon atoms, an amino group having one or two alkyl groups having 1 to 6 carbon atoms and having a polymerizable group, or an amino group in which two substituted alkyl groups are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms. An unsubstituted amino group is -NH2.).) etc. are mentioned. Examples of the polymerizable group include an acryloyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, etc. 【0085】 Specific examples of azo dyes represented by formula (II) include, for example, compounds represented by any of the following formulas (II-1) to (II-8). These azo dyes may be used individually or in mixtures of two or more. 【0086】 [ka] [In formulas (II-1) to (II-8), B 1 ~B 30 These independently represent a hydrogen atom, a C1-C6 alkyl group, a C1-C6 alkenyl group, a C1-C4 alkoxy group, a cyano group, a nitro group, a substituted or unsubstituted amino group (as defined above), a chlorine atom, or a trifluoromethyl group. n1 to n4 represent integers from 0 to 3, independently of each other. If n1 is 2 or more, multiple B 2 They may be the same or different from each other. If n2 is 2 or more, multiple B 6 They may be the same or different from each other. If n3 is 2 or more, multiple B 9 They may be the same or different from each other. If n4 is 2 or more, multiple B 14 They may be the same or different from each other. 【0087】 In the present invention, a polarizing element can be manufactured by, for example, the following method. A composition containing a polymerizable liquid crystal compound and a dichroic dye, optionally diluted with a solvent (hereinafter also referred to as the "polarizing film forming composition") is applied to an alignment film formed on a substrate by the method described above. Next, by polymerizing the mixture containing the polymerizable liquid crystal compound and the dichroic dye after drying the solvent as needed, a polymer of the polymerizable liquid crystal compound in an oriented state is obtained. By polymerizing the polymerizable liquid crystal compound while maintaining the horizontal orientation of the polymerizable liquid crystal compound and the dichroic dye, a liquid crystal cured film maintaining the orientation state is obtained, and such a liquid crystal cured film constitutes a polarizing film, forming a polarizing element including a substrate, an alignment film, and a polarizing film. The polarizing film forming composition may also contain components such as a solvent, a polymerization initiator, a photosensitizer, a leveling agent, and a reactive additive. Furthermore, the preparation of the polarizing film forming composition and the method of applying it can be similarly illustrated by the methods described for the preparation of the alignment film and the method of applying it. 【0088】 The content of polymerizable liquid crystal compounds in the polarizing film-forming composition (total amount if multiple types are included) is usually 60 to 99 parts by mass, preferably 70 to 95 parts by mass, and more preferably 75 to 90 parts by mass, per 100 parts by mass of solid content of the polarizing film-forming composition, from the viewpoint of exhibiting liquid crystal properties. Furthermore, the content of dichroic dyes (total amount if multiple types are included) is usually 1 to 30 parts by mass, preferably 2 to 20 parts by mass, and more preferably 3 to 15 parts by mass, per 100 parts by mass of solid content of the polarizing film-forming composition, from the viewpoint of obtaining good light absorption characteristics. Here, "solid content" refers to the total amount of components from the polarizing film-forming composition excluding the solvent. 【0089】 The solvent used in the polarizing film-forming composition can be appropriately selected depending on the solubility of the polymerizable liquid crystal compound and dichroic dye used. Specifically, the same solvents as those previously exemplified can be used in the alignment film-forming composition. One solvent may be used alone, or two or more solvents may be used in combination. The solvent content is preferably 100 to 1900 parts by mass, and more preferably 150 to 900 parts by mass, per 100 parts by mass of solid content of the polarizing film-forming composition. 【0090】 Polymerization initiators used in polarizing film-forming compositions are compounds capable of initiating the polymerization reaction of polymerizable liquid crystal compounds, and photopolymerization initiators are preferred because they can initiate the polymerization reaction under lower temperature conditions. Specifically, photopolymerization initiators that can generate active radicals or acids upon the action of light are mentioned, and among these, photopolymerization initiators that generate radicals upon the action of light are preferred. Polymerization initiators can be used alone or in combination of two or more types. 【0091】 As photopolymerization initiators, known photopolymerization initiators can be used. For example, photopolymerization initiators that generate active radicals include self-cleaving type photopolymerization initiators and hydrogen abstraction type photopolymerization initiators. Self-cleaving photopolymerization initiators include self-cleaving benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, azo compounds, etc. In addition, hydrogen abstraction type photopolymerization initiators include hydrogen abstraction benzophenone compounds, benzoin ether compounds, benzyl ketal compounds, dibenzosverone compounds, anthraquinone compounds, xanthone compounds, thioxanthone compounds, halogenoacetophenone compounds, dialkoxyacetophenone compounds, halogenobisimidazole compounds, halogenotriazine compounds, triazine compounds, etc. iodonium salts and sulfonium salts can be used as photopolymerization initiators that generate acid. 【0092】 Among these, reactions at low temperatures are preferred from the viewpoint of preventing the dissolution of the dye, and self-cleaving photopolymerization initiators are preferred from the viewpoint of reaction efficiency at low temperatures, with acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, and oxime ester compounds being particularly preferred. 【0093】 The content of the polymerization initiator in the polarizing film-forming composition is preferably 1 to 10 parts by mass, and more preferably 1 to 8 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. 【0094】 The photosensitizer used in the polarizing film-forming composition is the same as the photosensitizer previously exemplified for use in the alignment film-forming composition. The photosensitizer may be used alone or in combination of two or more types. The content of the photosensitizer is preferably 0.1 to 30 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. 【0095】 The leveling agent used in the polarizing film-forming composition has the function of adjusting the fluidity of the polarizing film-forming composition and making the coating obtained by applying the polarizing film-forming composition flatter. Specifically, surfactants are examples of such agents. As the leveling agent, at least one selected from the group consisting of leveling agents mainly composed of polyacrylate compounds and leveling agents mainly composed of fluorine atom-containing compounds is preferred. Leveling agents can be used alone or in combination of two or more types. 【0096】 If the polarizing film-forming composition contains a leveling agent, its content is preferably 0.05 to 5 parts by mass, and more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. 【0097】 Reactive additives used in compositions for forming polarizing films can generally improve the adhesion of the polarizing film. Preferred reactive additives have carbon-carbon unsaturated bonds and active hydrogen reactive groups within their molecules. Here, "active hydrogen reactive groups" refer to groups that react to active hydrogen, such as carboxyl groups (-COOH), hydroxyl groups (-OH), and amino groups (-NH2). Typical examples include glycidyl groups, oxazoline groups, carbodiimide groups, aziridine groups, imide groups, isocyanate groups, thioisocyanate groups, and maleic anhydride groups. The number of carbon-carbon unsaturated bonds and active hydrogen reactive groups in a reactive additive is usually 1 to 20, preferably 1 to 10. 【0098】 In reactive additives, it is preferable that at least two active hydrogen reactive groups are present, and in this case, the multiple active hydrogen reactive groups may be the same or different. 【0099】 The carbon-carbon unsaturated bond in the reactive additive may be a carbon-carbon double bond, a carbon-carbon triple bond, or a combination thereof, but a carbon-carbon double bond is preferred. In particular, the reactive additive preferably contains a carbon-carbon unsaturated bond as a vinyl group and / or a (meth)acrylic group. Furthermore, the reactive additive is preferably one in which the active hydrogen reactive group is selected from the group consisting of epoxy groups, glycidyl groups, and isocyanate groups, and a reactive additive having both an acrylic group and an isocyanate group is more preferred. 【0100】 Specific examples of reactive additives include compounds having a (meth)acrylic group and an epoxy group, such as methacryloxyglycidyl ether and acryloxyglycidyl ether; compounds having a (meth)acrylic group and an oxetane group, such as oxetane acrylate and oxetane methacrylate; compounds having a (meth)acrylic group and a lactone group, such as lactone acrylate and lactone methacrylate; compounds having a vinyl group and an oxazoline group, such as vinyl oxazoline and isopropenyloxazoline; and oligomers of compounds having a (meth)acrylic group and an isocyanate group, such as isocyanatomethyl acrylate, isocyanatomethyl methacrylate, 2-isocyanatoethyl acrylate and 2-isocyanatoethyl methacrylate. In addition, compounds having a vinyl group or vinylene group and an acid anhydride, such as methacrylic anhydride, acrylic anhydride, maleic anhydride and vinyl maleic anhydride, are also included. Among these, methacryloxyglycidyl ether, acryloxyglycidyl ether, isocyanatomethyl acrylate, isocyanatomethyl methacrylate, vinyl oxazoline, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, and the above oligomers are preferred, and isocyanatomethyl acrylate, 2-isocyanatoethyl acrylate, and the above oligomers are particularly preferred. 【0101】 When the polarizing film-forming composition contains a reactive additive, the amount of the reactive additive is usually 0.01 to 10 parts by mass, preferably 0.1 to 5 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound. 【0102】 A polarizing film is formed by polymerizing a liquid crystalline substance while maintaining its liquid crystal state. The polymerization method can be appropriately selected from photopolymerization or thermal polymerization, etc., depending on the type of polymerizable group. In one embodiment of the present invention, photopolymerization is preferred as the polymerization method because polymerization can be performed at low temperatures and it is easy to manufacture industrially. In photopolymerization, the light irradiated onto the dry coating film is appropriately selected depending on the type of polymerizable liquid crystal compound etc. contained in the dry coating film (particularly the type of polymerizable group possessed by the polymerizable liquid crystal compound etc.), the type of polymerization initiator and their amounts, etc. Specific examples include one or more active energy rays selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, alpha rays, beta rays and gamma rays, and active electron beams. Among these, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and because photopolymerization equipment widely used in this field can be used. It is preferable to select the types of polymerizable liquid crystal compound and polymerization initiator contained in the polarizing film forming composition so that photopolymerization is possible with ultraviolet light. Furthermore, the polymerization temperature can be controlled by cooling the dried coating film with an appropriate cooling method while irradiating it with light during polymerization. Patterned polarizing films can also be obtained by performing masking and development during photopolymerization. 【0103】 Examples of the light sources for the activated 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 380-440 nm, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, and the like. 【0104】 The UV irradiation intensity is typically 10-3,000 mW / cm². 2The ultraviolet irradiation intensity is preferably in the wavelength range effective for activating the polymerization initiator. The 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 irradiation is performed once or multiple times at such ultraviolet irradiation intensity, the accumulated light amount is 10 to 3,000 mJ / cm². 2 Preferably 50 to 2,000 mJ / cm² 2 More preferably 100-1,000 mJ / cm² 2 That is the case. 【0105】 The thickness of the polarizing element, which includes a substrate, an alignment film, and a polarizing film (preferably a polarizing element consisting of a substrate, an alignment film, and a polarizing film), can be appropriately determined depending on the application of the optical laminate into which the polarizing element is incorporated, but is preferably 1 μm or more, more preferably 2 μm or more, preferably 10 μm or less, and more preferably 9 μm or less. When the thickness of the polarizing element is within the above range, it is easily possible to make it ultra-thin. The thickness of the polarizing element can be measured using an interferometer, laser microscope, or stylus-type thickness gauge, etc. 【0106】 Since a photo-alignment film having a desired orientation-regulating force can be produced from the photo-alignment film-forming composition of the present invention, various liquid crystal compounds can be liquid crystal-aligned in a desired direction using the photo-alignment film-forming composition of the present invention. Therefore, on the photo-alignment film formed from the photo-alignment film-forming composition of the present invention, a phase difference film can be formed, for example, by polymerizing a polymerizable liquid crystal compound instead of the polarizing film. [Examples] 【0107】 The present invention will be described more specifically below based on examples and comparative examples, but the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" in the examples mean mass percent and parts by mass, respectively. 【0108】 (1) Preparation of composition for photoalignment film formation Synthesis Example 1: Synthesis of Photo-Orienting Polymer 1 The photo-oriented polymer 1 consists of the following structural units. [Photo-oriented polymer 1] [ka] 【0109】 [Synthesis scheme for photo-oriented polymer 1] [ka] 【0110】 [Synthesis of compound (a1-1-1)] 50 g (258 mmol) of ferulic acid was dissolved in 360 g of methanol. To the resulting solution, 10 g of sulfuric acid was added at room temperature, and the mixture was heated until reflux occurred. The reaction was then carried out under reflux for 2 hours. After cooling the resulting reaction solution, 150 g of ice and 150 g of water were added. The supernatant was removed by decantation, and 150 g of water at 5°C was added to induce crystallization. The resulting white crystals were filtered. The filtered white crystals were further washed with 1 M aqueous sodium bicarbonate solution and water, and then vacuum-dried to obtain 22.2 g of compound (a1-1-1). The yield was 83% based on ferulic acid. 【0111】 [Synthesis of compound (b1-1-1)] Compound (a1-1-1) 25 g (120 mmol) was dissolved in 250 g of dimethylacetamide. To the resulting solution, 33.19 g (240 mmol) of potassium carbonate and 1.99 g (12 mmol) of potassium iodide were added. 6-chlorohexanol was added dropwise to the resulting dispersion, and the mixture was stirred at room temperature for 1 hour, then stirred at 70°C for 8 hours. The resulting reaction solution was filtered to remove insoluble matter. 200 g of methyl isobutyl ketone and 300 g of water were added to the filtrate, stirred, allowed to stand, and the organic layer was recovered by liquid-liquid extraction. 200 g of water was added to the recovered organic layer, and the washing procedure of stirring, standing, and liquid-liquid extraction was repeated twice. The solvent was removed from the recovered organic layer by vacuum distillation using an evaporator to obtain the crude product of compound (b1-1-1). 【0112】 [Synthesis of compound (c1-1-1)] The entire amount of the crude product of compound (b1-1-1) was dissolved in 185 g of ethanol. To the resulting solution, 92 g of water and 14.41 g (360 mmol) of sodium hydroxide were added and the mixture was stirred at 80°C for 1 hour. After cooling the reaction solution to approximately 3°C, the pH was adjusted to 2 by adding 2 M hydrochloric acid aqueous solution while maintaining the temperature below 5°C. The acid-precipitated white precipitate was collected by filtration, washed twice with a mixed solution of 100 g of water and 80 g of methanol, and then vacuum-dried to obtain 30.4 g of compound (c1-1-1). The yield was 86% based on compound (a1-1-1). 【0113】 [Synthesis of compound (M1-1-1)] 27.46 g (93 mmol) of compound (c1-1-1) was dissolved in 280 g of chloroform. To the resulting solution, 2.06 g of BHT (di-t-butyl-hydroxytoluene) and 37.73 g (373 mmol) of triethylamine were added as polymerization inhibitors, and the mixture was stirred under ice cooling. 29.26 g (260 mmol) of methacrylate chloride was added dropwise to the reaction solution, and the mixture was stirred for 5 hours while maintaining a temperature below 5°C. 5.7 g of dimethylaminopyridine and 190 g of water were added to the resulting reaction solution, and the mixture was stirred at room temperature for 12 hours. After standing, the organic layer was collected, and 100 g of 2N hydrochloric acid aqueous solution was added to this organic layer. A series of washing operations involving stirring, standing, and liquid-liquid extraction were repeated twice. The organic layer was collected, and 300 g of n-heptane was added, and the precipitated crystals were collected by filtration. After washing twice with a mixed solvent consisting of 100 g of water and 80 g of methanol, the compound (M1-1-1) was vacuum-dried to obtain 22.0 g. The yield was 65% based on compound (c1-1-1). 【0114】 [Synthesis of photo-oriented polymer 1] In a Schlenk tube, 1.00 g (2.76 mmol) of compound (M1-1-1) and 10 g of tetrahydrofuran were added. After deoxygenation, 2.27 mg of azobisisobutyronitrile (AIBN) was added while flowing nitrogen, and the mixture was stirred at 60°C for 72 hours. The resulting reaction solution was added to 200 g of toluene. The precipitate was filtered, washed with heptane, and vacuum-dried to obtain 0.75 g of photo-oriented polymer 1. The yield was 75% based on compound (M1-1-1). GPC measurement revealed that the obtained photo-oriented polymer 1 had a number-average molecular weight of 28200, a weight-average molecular weight of approximately 51300, and a Mw / Mn ratio of 1.82, with a monomer content of 0.5%. 【0115】 Synthesis Examples 2 and 3: Synthesis of Photo-Oriented Polymer 2 and Photo-Oriented Polymer 3 Photo-oriented polymers 2 and 3 were synthesized according to the method described in Macromolecules, Vol.39, No.26, 9357 (2006). The numbers in parentheses in the following structural formulas represent the mole fraction of each structural unit relative to the total structural units of photo-oriented polymers 2 and 3. [ka] [ka] 【0116】 Synthesis Example 4: Synthesis of Photo-Orienting Polymer 4 Following the synthesis methods for photo-oriented polymers 2 and 3 described above, photo-oriented polymer 4 was prepared with the following structure. The numbers in parentheses in the following structural formula represent the mole fraction of each structural unit relative to the total structural units of photo-oriented polymer 4. [ka] 【0117】 The weight-average molecular weights of the polymers, calculated on a polystyrene basis, were approximately 100,000 for polymer 2, 90,000 for polymer 3, and 95,000 for polymer 4. 【0118】 Two parts of the photo-orienting polymer (any of photo-orienting polymers 1 to 4) prepared above were mixed with 98 parts of o-xylene, and the mixture was stirred at 80°C for 1 hour to obtain a polymer solution. Hereinafter, the polymer solution containing polymer 1, the polymer solution containing polymer 2, the polymer solution containing polymer 3, and the polymer solution containing polymer 4 will be referred to as polymer solution 1, polymer solution 2, polymer solution 3, and polymer solution 4, respectively. 【0119】 (2) Formation of photoalignment film composition and laminate Example 1 To a polymer solution, 10 parts by mass of KBE-903 (manufactured by Shin-Etsu Chemical Co., Ltd.) and an amount of formic acid with a molar ratio of 5 [mol / mol] to KBE-903 were added to prepare a photo-alignment film forming composition. 【0120】 (3) Preparation of a composition for forming a polarizing film A polarizing film-forming composition was obtained by mixing the following components and stirring at 80°C for 1 hour. The polymerizable liquid crystal compound and dichroic dye listed below were prepared by the methods described in the examples of Japanese Patent Application Publication No. 2013-101328. 【0121】 • Polymerizable liquid crystal compound represented by formula (A-6) 75 parts [ka] 【0122】 • 25 parts of polymerizable liquid crystal compound represented by formula (A-7) [ka] 【0123】 • Dichroic dye (1) shown below: 2.8 parts [ka] 【0124】 • Dichroic dye (2) shown below: 2.8 parts [ka] 【0125】 • Dichroic dye (3) shown below: 2.8 parts [ka] 【0126】 • Polymerization initiator: 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369; manufactured by Ciba Specialty Chemicals) 6 parts • Leveling agent: Polyacrylate compound (BYK-361N; manufactured by BYK-Chemie) 1.2 parts 【0127】 Compound B-2: Compound having the following structure (Trade name: Laromer® LR-9000, manufactured by BASF) 2 copies [ka] • Solvent: Cyclopentanone 250 parts 【0128】 (4) Creation of acrylic resin film Based on the description in Japanese Patent Publication No. 2020-56835, an acrylic resin film was prepared. A composition for forming an acrylic resin layer was obtained by mixing 90 parts of a polyfunctional acrylate monomer (ethylene oxide-modified (12-unit) dipentaerythritol hexaacrylate (manufactured by Shin Nakamura Chemical Co., Ltd., "NK Ester A-DPH-12E"), 10 parts of a urethane acrylate polymer (urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., "Shiko UV-3310B")), 3 parts of a radical polymerization initiator (phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (manufactured by BASF, "Irgacure 819")), and 10 parts of a solvent (methyl ethyl ketone), and stirring at 50°C for 4 hours. After corona treatment was applied to the release-treated surface of a polyethylene terephthalate film (SP-PLR382050, manufactured by Lintec Corporation) (release film), an acrylic resin layer-forming composition was applied by bar coating (#2 30 mm / sec), and an exposure dose of 500 mJ / cm² was applied using a UV irradiation device (SPOT CURE SP-7; manufactured by Ushio Inc.). 2 By irradiating the coating layer of the resin layer-forming composition with ultraviolet light (based on 365 nm), a release film with a resin layer was obtained in which an acrylic resin layer was formed on the surface of the release film. The thickness of the acrylic resin layer was 1.5 μm. 【0129】 (5) Fabrication of polarizing elements An acrylic resin film, used as the base material, was cut into a 10cm x 10cm rectangle. To introduce polar groups to the surface of the base material, it was treated once using a corona treatment device (AGF-B10; manufactured by Kasuga Electric Co., Ltd.) at an output of 0.3kW and a processing speed of 3m / min. The photo-alignment film-forming composition was applied to the corona-treated surface using a bar coater, dried at 80°C for 1 minute, and then treated with a polarizing UV irradiation device (SPOT CURE SP-7 with polarizer unit; manufactured by Ushio Inc.) at a rate of 100mJ / cm². 2 A photo-aligned film was formed by polarized UV exposure with the integrated light intensity. The thickness of the obtained photo-aligned film was measured using an ellipsometer M-220 (manufactured by JASCO Corporation) and was found to be 40 nm. 【0130】 The obtained photo-alignment film was coated with a polarizing film-forming composition using a bar coater, and then dried in a drying oven set to 120°C for 1 minute. 【0131】 Subsequently, ultraviolet light was irradiated using a high-pressure mercury lamp (UniCure VB-15201BY-A, manufactured by Ushio Inc.) (under a nitrogen atmosphere, wavelength: 365 nm, integrated light intensity at 365 nm: 1000 mJ / cm²). 2 By doing so, a polarizing film in which polymerizable liquid crystal compounds and dichroic dyes are oriented was formed, and a laminate (1) consisting of a substrate / photo-alignment film / polarizing film was obtained. At this time, the thickness of the polarizer was measured with an ellipsometer and was found to be 2.0 μm. 【0132】 Examples 2-9 The photo-alignment film-forming composition and laminate were prepared in the same manner as in Example 1, except that the amount of acid added to the photo-alignment film-forming composition was changed as shown in Table 1. 【0133】 Examples 10-17 In the photo-alignment film formation composition, the photo-alignment film formation composition and laminate were prepared in the same manner as in Example 4, except that the amount of silane coupling agent added was changed as shown in Table 1. 【0134】 Example 18 A photo-alignment film-forming composition and laminate were prepared in the same manner as in Example 1, except that p-toluenesulfonic acid was used as the acid and the molar ratio of the acid to the silane coupling agent was set to 3. 【0135】 Example 19 A photo-alignment film-forming composition and laminate were prepared in the same manner as in Example 1, except that acrylic acid was used as the acid and the molar ratio of the acid to the silane coupling agent was set to 22. 【0136】 Example 20 A photo-alignment film-forming composition and laminate were prepared in the same manner as in Example 19, except that acetic acid was used as the acid. 【0137】 Example 21 A photoalignment film-forming composition was prepared in the same manner as in Example 3, except that polymer solution 2 was used instead of polymer solution 1. 【0138】 Example 22 A photoalignment film-forming composition was prepared in the same manner as in Example 3, except that polymer solution 3 was used instead of polymer solution 1. 【0139】 Example 23 A photo-alignment film-forming composition and laminate were prepared in the same manner as in Example 3, except that polymer solution 4 was used instead of polymer solution 1. 【0140】 Comparative Example 1 A photo-alignment film-forming composition and laminate were prepared in the same manner as in Example 1, except that a silane coupling agent and acid were not added. 【0141】 Comparative Example 2 A photo-alignment film-forming composition and laminate were prepared in the same manner as in Example 1, except that an acid was not added. 【0142】 Comparative Example 3 A photo-alignment film-forming composition and laminate were prepared in the same manner as in Comparative Example 2, except that polymer solution 2 was used instead of polymer solution 1. 【0143】 Comparative Example 4 A photo-alignment film-forming composition and laminate were prepared in the same manner as in Comparative Example 2, except that polymer solution 3 was used instead of polymer solution 1. 【0144】 Comparative Example 5 A photo-alignment film-forming composition and laminate were prepared in the same manner as in Comparative Example 2, except that polymer solution 4 was used instead of polymer solution 1. 【0145】 (6) Evaluation (6)-1. Liquid stability of composition for forming photo-alignment film The liquid stability of the photo-alignment film composition was evaluated as follows. After the production of the photo-alignment film-forming composition, it was filled into brown bottles and stored at 25°C. After a predetermined time had elapsed since production (1 hour, 2 hours, 3 hours, 1 day, 5 days, and 7 days), the presence or absence of turbidity and precipitates was visually checked, and the liquid stability was evaluated according to the following criteria. ○: No cloudiness (no cloudiness can be observed even when light is shone on it) △: Slight clouding (clouding can be seen when light is shone on it) ×: Cloudy (Cloudiness can be seen even without shining a light on it) 【0146】 (6)-2. Adhesion between the substrate and the orientation film The adhesion between the substrate (acrylic resin film) and the photo-alignment film in the resulting laminate was evaluated by the following cross-hatch test. (Cross-hatch test) The adhesion between the photo-alignment film and the acrylic resin film in the resulting laminate was evaluated by a cross-hatch test (JIS "grid adhesion test") in accordance with JIS D0202-1988. A grid pattern was created on the acrylic resin film surface of a 10cm x 10cm laminate by making 10 x 10 scratches at 2mm intervals, penetrating through to the acrylic resin film and the photo-alignment film. Adhesive tape (25mm wide, manufactured by Nichiban) was completely adhered to this grid surface. The adhesive tape was then peeled off at a 90° angle to the surface. The number of grids that remained attached was measured, and the adhesion was evaluated according to the following criteria. 〇:50 or more remaining △: 10 or more and 49 or less remaining ×: Less than 9 Furthermore, X-ray photoelectron spectroscopy (XPS) was used to confirm that the delamination interface for the detached grid pattern was between the photo-aligned film and the substrate. 【0147】 (6) - Presence or absence of poor orientation after 3.7 days An alignment film was formed from a photo-alignment film-forming composition that had been manufactured 7 days prior, and a laminate was created using this alignment film in the same procedure as described above. A 10cm x 10cm laminate was placed under a backlight and visually observed, and evaluated according to the following criteria. ○: No orientation defects △: Partially occurring orientation defects ×: Orientation defects occur throughout the entire surface. 【0148】 Table 1 shows the evaluation results of the photo-alignment film-forming compositions and laminates obtained in the examples and comparative examples. In Table 1, SC represents a silane coupling agent, and bp represents the boiling point. The amount of silane coupling agent added is expressed in parts by mass per 100 parts by mass of the photo-aligning polymer. In the table, "-" in the evaluation results indicates that evaluation was not performed. 【0149】 [Table 1] 【0150】 Compared to Comparative Example 1, which does not contain a silane coupling agent or acid, the adhesion between the photo-alignment film formed from the photo-alignment film-forming compositions of Examples 1 to 20 and the substrate is excellent. Furthermore, compared to Comparative Examples 2 to 5, which contain a silane coupling agent but do not contain acid, the photo-alignment film-forming compositions of Examples 1 to 23 show improved liquid stability.

Claims

[Claim 1] The polymer comprises a photo-orienting polymer having a photoreactive group, a silane coupling agent, an acid, and a solvent. The molar ratio of the acid to the silane coupling agent (acid [moles] / silane coupling agent [moles]) is 15 or more and 50 or less. The weight-average molecular weight of the photo-oriented polymer is 51,300 or more and 1,000,000 or less. A composition for forming a photo-aligned film, wherein the acid is formic acid. [Claim 2] The composition according to claim 1, wherein the photo-oriented polymer has a photoreactive group that undergoes a dimerization reaction. [Claim 3] The composition according to claim 1 or 2, wherein the photo-oriented polymer is a (meth)acrylic polymer. [Claim 4] The composition according to any one of claims 1 to 3, wherein the photo-oriented polymer further has a carboxyl group. [Claim 5] The composition according to any one of claims 1 to 4, wherein the silane coupling agent has at least one group selected from the group consisting of a primary amino group and a secondary amino group. [Claim 6] The composition according to any one of claims 1 to 5, wherein the content of the silane coupling agent is 0.5 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the photo-oriented polymer. [Claim 7] A photo-aligned film obtained by curing the composition according to any one of claims 1 to 6. [Claim 8] A laminate comprising a substrate and the photo-alignment film described in claim 7. [Claim 9] The laminate according to claim 8, wherein the film thickness of the substrate is 1 μm or more and 20 μm or less. [Claim 10] A polarizing element comprising a substrate, a photoalignment film according to claim 7, and a polarizing film. [Claim 11] The polarizing element according to claim 10, wherein the thickness is 1 μm or more and 10 μm or less.

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