CN114879296A

CN114879296A - Polarizing element and method for manufacturing the same

Info

Publication number: CN114879296A
Application number: CN202210113372.XA
Authority: CN
Inventors: 铃木纯次; 幡中伸行; 太田阳介; 中野雅也
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2021-02-05
Filing date: 2022-01-29
Publication date: 2022-08-09
Also published as: JP2022120660A; KR20220113269A; TW202242459A

Abstract

The invention aims to provide a polarizing element which is not easy to generate stripping when being bent. The polarizing element of the present invention is formed by sequentially laminating a substrate, an alignment film and a polarizing film, wherein the alignment film is formed by curing an alignment film-forming composition containing an alignment polymer (A-1) and a compound (A-2) having an active hydrogen reactive group.

Description

Polarizing element and method for manufacturing the same

Technical Field

The present invention relates to a polarizing element, a method for manufacturing the polarizing element, and a flat panel display device and a flexible display material including the polarizing element.

Background

Polarizing plates are used in image display devices represented by organic electroluminescence (hereinafter also referred to as organic EL) display devices after being bonded to image display elements such as liquid crystal cells and organic EL display elements. In recent years, with the demand for reduction in thickness of such image display devices, further reduction in thickness has been demanded for polarizing plates and polarizing films, which are one of the components thereof, and various polarizing plates and polarizing films have been proposed in response to the demand. For example, patent document 1 discloses an ultra-thin polarizing element in which a polarizing layer formed by aligning a polymerizable liquid crystal compound and a dichroic dye is provided on a substrate with a photo-alignment layer interposed therebetween.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-102479

Disclosure of Invention

Problems to be solved by the invention

It is expected that the ultra-thin polarizing element can be suitably used for a flexible display or the like. However, when the bending diameter is small, peeling of the polarizing film or the like may occur at the bending portion, and thus a polarizing element having high bending resistance more suitable for use in a flexible display is required.

The invention aims to provide a polarizing element which is not easy to generate stripping when being bent.

Means for solving the problems

The present inventors have conducted extensive studies to solve the above problems, and as a result, the present invention has been completed. That is, the present invention includes the following embodiments.

[1] A polarizing element comprising a substrate, an alignment film and a polarizing film laminated in this order,

the alignment film is formed by curing an alignment film-forming composition containing an alignment polymer (A-1) and a compound (A-2) having an active hydrogen-reactive group.

[2] The polarizing element according to the above [1], wherein the polarizing film is a polarizing film obtained by curing a composition for forming a polarizing film comprising a polymerizable liquid crystal compound (B-1), a compound (B-2) having an active hydrogen reactive group, and a dichroic dye (B-3).

[3] The polarizing element according to the above [1] or [2], wherein the compound (A-2) further has an active hydrogen-containing group.

[4] The polarizing element according to any one of the above [1] to [3], wherein the alignment polymer (A-1) is a polymer having a photoreactive group that causes dimerization reaction.

[5] The polarizing element according to any one of the above [1] to [4], wherein the alignment polymer (A-1) is a (meth) acrylic polymer.

[6] The polarizing element according to any one of [1] to [5], wherein the weight average molecular weight of the alignment polymer (A-1) is 10000 to 1000000.

[7] The polarizing element according to any one of the above [1] to [6], wherein the compound (A-2) is a silane coupling agent.

[8] The polarizing element according to any one of the above [1] to [7], wherein the compound (A-2) is a silane coupling agent containing at least 1 functional group selected from a primary amino group, a secondary amino group, a hydroxyl group and a mercapto group.

[9] The polarizing element according to any one of [1] to [8], wherein the content of the compound (A-2) is 1 part by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the alignment polymer (A-1).

[10] The polarizing element according to any one of the above [2] to [9], wherein the compound (B-2) further has a polymerizable group.

[11] The polarizing element according to [10], wherein the polymerizable group is a (meth) acryloyl group.

[12] The polarizing element according to any one of the above [2] to [11], wherein the compound (B-2) has 1 or more isocyanate groups and 1 or more (meth) acryloyl groups.

[13] The polarizing element according to any one of [2] to [12], wherein the content of the compound (B-2) is 0.1 part by mass or more and 12 parts by mass or less with respect to 100 parts by mass of the polymerizable liquid crystal compound (B-1).

[14] The polarizing element according to any one of [2] to [13], wherein the dichroic dye (B-3) comprises a compound represented by formula (I):

K ¹ (-N＝N-K ² ) _p -N＝N-K ³ (I)

[ in the formula (I),

K ¹ and K ³ Independently represent an optionally substituted phenyl group, an optionally substituted naphthyl group, an optionally substituted phenyl benzoate group or an optionally substituted 1-valent heterocyclic group,

K ² represents 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 (Japanese: 4, 4' - スチルベニレン group) or a 2-valent heterocyclic group which may have a substituent,

p represents an integer of 0 to 4, and when p is an integer of 2 or more, a plurality of K' s ² These may be the same as or different from each other, and may be replaced with a bond of-C ═ C-, -COO-, -NHCO-, -N ═ CH-in a range where absorption is exhibited in the visible region.]。

[15] The polarizing element according to any one of the above [2] to [14], wherein the polymerizable liquid crystal compound (B-1) is a liquid crystal compound exhibiting smectic liquid crystallinity.

[16] The polarizing element according to any one of [1] to [15], wherein the thickness of the base material is 1 μm or more and 10 μm or less.

[17] The polarizing element according to any one of [1] to [16], wherein a surface of the polarizing film opposite to the alignment film includes an overcoat layer.

[18] A method for manufacturing a polarizing element in which a substrate, an alignment film, and a polarizing film are laminated in this order, the method comprising:

(1) a step in which a coating film of an alignment film-forming composition comprising an alignment polymer (A-1) and a compound (A-2) having an active hydrogen-reactive group is formed on a substrate having a polar group, and the active hydrogen-reactive group of the compound (A-2) is reacted with the polar group of the substrate to form a bond by drying the coating film;

(2) forming an alignment film by subjecting the dried coating film obtained in step (1) to rubbing treatment or light irradiation;

(3) forming a coating film of a composition for forming a polarizing film, which comprises a polymerizable liquid crystal compound (B-1), a compound (B-2) having an active hydrogen-reactive group, and a dichroic dye (B-3), on the alignment film obtained in the step (2), and drying the coating film; and

(4) and (3) curing the polymerizable liquid crystal compound (B-1) and the dichroic dye (B-3) in the dried coating film obtained in step (3) in an oriented state to form a polarizing film.

[19] The production method according to [18], further comprising a step of forming an overcoat layer on the polarizing film formed in the step (4).

[20] A flat panel display device comprising the polarizing element according to any one of [1] to [17 ].

[21] A flexible display material comprising the polarizing element according to any one of [1] to [17 ].

Effects of the invention

According to the present invention, a polarizing element in which peeling is less likely to occur when bent can be provided.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail. The scope of the present invention is not limited to the embodiments described herein, and various modifications may be made without departing from the scope of the present invention.

The polarizing element of the present invention comprises a substrate, an alignment film, and a polarizing film in this order. In the polarizing element of the present invention, as a configuration for more easily achieving the effects of the present invention, it is preferable that the substrate, the alignment film, and the polarizing film are adjacent to each other. The polarizing element of the present invention may be configured to include other layers in addition to the substrate, the alignment film, and the polarizing film, as long as the effects of the present invention are not affected. Examples of the other layers include an overcoat layer provided on a polarizing film, and an adhesive layer for bonding to an image display element such as a liquid crystal cell or an organic EL display element.

< alignment film >

The polarizing element of the present invention comprises an alignment film obtained by curing an alignment film-forming composition comprising an alignment polymer (A-1) and a compound (A-2) having an active hydrogen-reactive group. In the present invention, the alignment film has an alignment regulating force for liquid crystal alignment in a desired direction of a polymerizable liquid crystal compound and a dichroic dye forming a polarizing film described later, and a polarizing film having a highly precise alignment can be easily obtained by applying a composition for forming a polarizing film containing a polymerizable liquid crystal compound or the like to the alignment film.

The state of liquid crystal alignment such as horizontal alignment, vertical alignment, hybrid alignment, and tilt alignment can be controlled by the properties of the alignment film and the polymerizable liquid crystal compound, and in the present invention, the combination thereof can be arbitrarily selected according to the desired alignment state. For example, the polymerizable liquid crystal compound can be aligned horizontally or hybrid-aligned by using an alignment film formed of a material exhibiting horizontal alignment as an alignment regulating force, and the polymerizable liquid crystal compound can be aligned vertically or obliquely by using an alignment film formed of a material exhibiting vertical alignment. The orientation direction such as horizontal orientation or vertical orientation refers to the long axis direction of the polymerizable liquid crystal compound that is oriented with the plane of the polarizing film as a reference. For example, the horizontal alignment means a state in which the long axis direction of the polymerizable liquid crystal compound is aligned in a direction parallel to the plane of the polarizing film, and the vertical alignment means a state in which the long axis direction of the polymerizable liquid crystal compound is aligned in a direction perpendicular to the plane of the polarizing film. The term "parallel to the plane of the polarizing film" means 0 ° ± 20 ° with respect to the plane of the polarizing film, and the term "perpendicular" means 90 ° ± 20 ° with respect to the plane of the polarizing film.

The alignment film of the present invention is formed from an alignment film-forming composition containing an alignment polymer (A-1). The orientation regulating force of the orientation film can be arbitrarily controlled by the surface state, the rubbing state, the polarized light irradiation condition, and the like, depending on the kind of the orientation polymer (a-1) contained in the composition for forming an orientation film. Further, the liquid crystal alignment can be controlled by selecting physical properties such as surface tension and liquid crystallinity of the polymerizable liquid crystal compound.

The alignment film is preferably insoluble in a solvent used when a polarizing film is formed on the alignment film, and has heat resistance for removal of the solvent and heat treatment for alignment of liquid crystals. Examples of the alignment film include a rubbing alignment film, a photo alignment film, and a groove (groove) alignment film made of an alignment polymer. In one embodiment of the present invention, the alignment film is preferably a photo-alignment film from the viewpoint of easy control of the alignment direction, accuracy of the alignment angle, and excellent quality in the production of the polarizing element.

When the alignment film is a rubbing alignment film formed of an alignment polymer, examples of the alignment polymer (a-1) include polyamide having an amide bond in the molecule, gelatin, polyimide having an imide bond in the molecule, and polyamic acid as a hydrolysate thereof, polyvinyl alcohol, alkyl-modified polyvinyl alcohol, polyacrylamide, polyoxazoles, polyethyleneimine, polystyrene, polyvinylpyrrolidone, polyacrylic acid, and polyacrylates. Hereinafter, the alignment polymer for a rubbing alignment film is also referred to as a "rubbing alignment polymer". Among them, polyvinyl alcohol is preferable as the rubbing-alignment polymer. The rubbing-alignment polymer may be used alone, or 2 or more kinds thereof may be used in combination.

When the alignment film is a photo-alignment film, the alignment polymer (a-1) is usually an alignment polymer having a photoreactive group. Hereinafter, the alignment polymer for forming the photo-alignment film is also referred to as a "photo-alignment polymer". In the present specification, the photoreactive group means a group that generates liquid crystal aligning ability by light irradiation, and in the polymer forming the photo alignment film, the photoreactive group contributes to imparting the liquid crystal aligning ability by the action of light. Specifically, the groups are groups in which the orientation of polymer molecules is induced by photoreaction, such as dimerization reaction, isomerization reaction, photocrosslinking reaction, or photolysis reaction, which is the origin of the liquid crystal orientation ability by light irradiation. The photo-reactive group of the photo-alignment polymer may be 1 kind or 2 or more kinds.

As the photoreactive group capable of causing the above-described reaction, a group having an unsaturated bond, particularly a double bond is preferable, and examples thereof include a group having at least 1 selected from 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).

Examples of the group having a C ═ C bond include a vinyl group, a polyene group, a stilbene onium group, a chalcone group, and a cinnamoyl group. Examples of the group having a C ═ N bond include groups having structures such as aromatic schiff bases and aromatic hydrazones. Examples of the group having an N ═ N bond include an azophenyl group, an azonaphthyl group, an aromatic heterocyclic azo group, a bisazo group, a formazan group, and a group having azoxybenzene as a basic structure. Examples of the group having a C ═ O bond include a benzophenone group, a coumarin group, an anthraquinone group, and a maleimide group. 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 haloalkyl groups. Among these, from the viewpoint of excellent alignment and reactivity, the photo-alignment polymer preferably has a photoreactive group that causes a dimerization reaction or a photocrosslinking reaction, and more preferably has a photoreactive group that causes a dimerization reaction.

The dimerization reaction is an addition reaction between 2 groups by the action of light, and typically is a reaction forming a ring structure. The group that causes the dimerization reaction is a group containing a carbon-carbon double bond (C ═ C bond) or a carbon-oxygen double bond (C ═ O bond) that causes dimerization reaction by light irradiation, and examples thereof include a group having a cinnamoyl structure, a group having a chalcone structure, a group having a coumarin structure, a group having a benzophenone structure, and a group having an anthracene structure. Among them, from the viewpoint of easy control of reactivity and excellent alignment restriction force in photo-alignment, a group having a cinnamoyl structure and a group having a chalcone structure are preferable, and a group having a cinnamoyl structure is more preferable. Further, the group having the above structure is advantageous in that the amount of polarized light irradiation necessary for photo-alignment is small, and a photo-alignment film having excellent thermal stability and stability with time can be easily obtained.

The photo-alignment polymer preferably has a photoreactive group that causes dimerization reaction at the end of a polymer side chain, more preferably has a group having a cinnamoyl structure or a group having a chalcone structure at the end of a polymer side chain, and even more preferably has a group having a cinnamoyl structure at the end of a polymer side chain. Examples of the photo-alignment polymer include polymers having a structure represented by the following formula (a 1') and/or a structure represented by the following formula (a1 ") in a side chain (hereinafter, these are also collectively referred to as" photo-alignment polymer (a) ").

[ solution 1]

[ formulae (A1 ') and (A1'),

k represents 0 or 1.

L ¹ Represents a single bond or-O-.

L ² Represents a single bond, -O-, -COO-, -OCO-, -N-, -CH-or-CH ₂ -。

R ¹ 、R ² And R ³ Each independently represents a hydrogen atom, a halogen atom, a haloalkyl group, a haloalkoxy 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 group, an amino group or a hydroxyl group, and the carboxyl group and the sulfonic group may form a salt with an alkali metal ion.

R ⁴ Represents a hydrogen atom, an alkyl group or a phenyl group.

It represents the bonding end to the main chain of the polymer. ]

L in the formulae (A1 ') and (A1') ² is-O-, -COO-, -OCO-, -N-, -C-or-CH ₂ In any of the above cases, the production of the photo-alignment polymer (a) becomes easy.

R in the formulae (A1 ') and (A1') ¹ 、R ² And R ³ Preferably, each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. As R ¹ 、R ² And R ³ Examples of the alkyl group 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.

The main chain of the photo-alignment polymer (A) is not particularly limited, and examples of the structure of the monomer unit forming the main chain include (meth) acrylate units selected from those represented by the formula (M-1) or (M-2); a (meth) acrylamide unit represented by the formula (M-3) or the formula (M-4); a vinyl ether unit represented by the formula (M-5) or (M-6); a methylstyrene unit represented by the formula (M-7) or (M-8) and a vinyl ester unit represented by the formula (M-9) or (M-10).

In the formulae (M-1) to (M-10), the bond to the structure represented by the formula (A1 ') or the formula (A1') or the bond to a spacer described later is shown. In the present specification, the "main chain of the photo-alignment polymer (a)" means the longest molecular chain among the molecular chains of the photo-alignment polymer (a).

[ solution 2]

The main chain of the photo-alignment polymer (a) may be a homopolymer formed of 1 kind of monomer unit, or may be a copolymer formed of 2 or more kinds of monomer units. When the main chain of the photo-alignment polymer (a) is a copolymer, the main chain may have any bonding pattern of an alternating type, a block type, a random type, or a graft type.

The structure of the monomer unit forming the main chain of the photo-alignment polymer (A) may be a silsesquioxane structure comprising repeating units represented by formulae (M-11) to (M-16) (シロセスシロキサン, Japanese). In the formulae (M-11) to (M-16), the bond site to the structure represented by the formula (A1 ') or the formula (A1') or the bond site to a spacer described later is shown.

[ solution 3]

In the formulae (M-11) to (M-16), R ⁵ Represents an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or a bond to another silicon atom via an oxygen atom. As R ³ Examples of the alkyl group having 1 to 6 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and the like, and among them, a methyl group and an ethyl group are preferable. As R ⁵ Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group and the like, and among them, methoxy group and ethoxy group are preferable.

In the formulae (M-13) and (M-14), Ph represents a 2-valent benzene ring which may have a substituent (e.g., phenylene). In the formula (M-16), Cy may be a 2-valent cyclohexane ring which may have a substituent (e.g., cyclohexane-1, 4-diyl), or the like.

n represents an integer of 1 to 4.

The main chain of the photo-alignment polymer (A) is preferably formed of a structural unit represented by any one of formulae (M-1) to (M-16), more preferably a structural unit represented by any one of formulae (M-1) to (M-10), and further preferably a structural unit selected from a (meth) acrylate unit and a (meth) acrylamide unit represented by formulae (M-1) to (M-4).

The monomer structural unit forming the main chain of the photo-alignment polymer (A) as shown in any of the formulae (M-1) to (M-16) may be directly bonded to the group shown in the formula (A1') or the formula (A1 "), or may be bonded via a linking group as an appropriate spacer unit. When the linkage is via a linking group, examples of the linking group include a carbonyloxy group (ester bond), an oxygen atom (ether bond), an imide group, a carbonylimino group (amide bond), an iminocarbonylimino group (urethane bond), a 2-valent aliphatic hydrocarbon group which may have a substituent, a 2-valent aromatic hydrocarbon group which may have a substituent, and a 2-valent group obtained by combining these groups. Examples of the substituted or unsubstituted aromatic hydrocarbon group having a valence of 2 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 them, an aliphatic hydrocarbon group is preferable, and an alkanediyl group having 1 to 11 carbon atoms which may have a substituent is more preferable. Examples of the alkanediyl group include a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, a heptamethylene group, an octamethylene group, a nonamethylene group, a decamethylene group, and an undecamethylene group, and these groups may be linear or branched. Examples of the substituent that the alkanediyl group may have include an alkoxy group having 1 to 4 carbon atoms.

The structure represented by formula (a 1') is preferably such that the photo-alignment polymer (a) is formed as a structural unit represented by formula (a1-1) (hereinafter, may be referred to as "structural unit (a 1-1)"), and in one embodiment of the present invention, the photo-alignment polymer (a) includes the structural unit (a 1-1). In addition, the structure represented by formula (a1 ") is preferably such that the photo-alignment polymer (a) is formed 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-alignment polymer (a) includes the structural unit (a 1-2).

[ solution 4]

In the formulae (A1-1) and (A1-2), L ¹ 、L ² 、R ¹ 、R ² 、R ³ 、R ⁴ And k are each synonymous with the letter in said formula (A1 ') or formula (A1'), SP ¹ M is an alkanediyl group having 1 to 11 carbon atoms which may have a substituent ¹ The structure shown is a structure shown by any one of formulas (M-1) to (M-16).

The photo-alignment polymer (a) may have a carboxyl group in addition to a photoreactive group, particularly a photoreactive group that causes dimerization reaction. The photo-alignment polymer (A) having a photoreactive group and a carboxyl group may be, for example, a polymer comprising a structural unit (A1-1), and as another embodiment, a polymer comprising, for example, a structure represented by formula (A1 '), a structure represented by formula (A1'), or a structural unit (A1-1) and/or a structural unit (A1-2), and further comprising a structural unit represented by formula (A1-3) (hereinafter also referred to as "structural unit (A1-3)").

[ solution 5]

In the formula (A1-3), l represents 0 or 1, SP ² Represents an alkanediyl group having 1 to 11 carbon atoms which may have a substituent. SP ² Specific examples of (2) and SP in the formulae (A1-1) and (A1-2) ¹ In the same manner as in the specific example of (A), M ² The structure shown is a structure shown by any one of formulas (M-1) to (M-16).

In the formula (A1-3), L ³ Represents a single bond or-O-, L ⁴ Represents a single bond, -O-, -COO-, -OCO-, -N-, -CH-or-CH ₂ -。

In the formula (A1-3), R ⁶ And R ⁷ Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms. As R ⁶ And R ⁷ Examples of the alkyl group 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.

When the photo-alignment polymer (A) includes the structural unit (A1-1) or the structural unit (A1-2) and the structural unit (A1-3), it is preferable that the molar fractions of the structural unit (A1-1), the structural unit (A1-2) and the structural unit (A1-3) to all the structural units forming the photo-alignment polymer (A) are p, q and r (here, p + r is 1 and q + r is 1) respectively, and the relationships of 0.10 < p, q ≦ 0.90 and 0.10 ≦ r < 0.90 are satisfied. In the photo-alignment polymer comprising the structural unit (A1-1), the number of the structural unit (A1-1) may be 1, or 2 or more. The photo-alignment polymer (a) may have a structural unit (hereinafter, sometimes referred to as "other structural unit") other than the structural units (a1-1), (a1-2) and the structural unit (a1-3) as long as the liquid crystal alignment ability by light irradiation is not significantly impaired.

The photo-alignment polymer (A) can be produced by (co) polymerizing a monomer from which the structural unit (A1-1) or the structural unit (A1-2) is derived and a monomer from which the structural unit (A1-3) and/or another structural unit are derived, which is used as needed. The copolymerization method may be any method known in the art, and may be, for example, a radical polymerization, a chain polymerization such as an anionic polymerization or a cationic polymerization, or an addition polymerization such as a coordination polymerization. The polymerization conditions may be appropriately determined depending on the kind of the monomer used, the amount thereof, and the like, in order to obtain the photo-alignment polymer (a) having a desired molecular weight.

In the present invention, the molecular weight of the oriented polymer (a-1) is a polystyrene-equivalent weight average molecular weight determined by Gel Permeation Chromatography (GPC), and is preferably 10000 or more and 1000000 or less, more preferably 15000 or more, further preferably 20000 or more, further preferably 500000 or less, further preferably 250000 or less. When the weight average molecular weight of the alignment polymer (a-1) is within the above range, the solvent resistance becomes good, and it is easy to obtain an alignment film which exhibits excellent liquid crystal alignment ability while securing high adhesion to a polarizing film to be formed on the alignment film thereafter.

The alignment polymer (a-1) in the present invention is preferably a photo-alignment polymer, more preferably a photo-alignment polymer (a), and even more preferably a (meth) acrylic polymer (particularly a (meth) acrylic photo-alignment polymer (a)). In particular, when the polymerizable liquid crystal compound forming the polarizing film is a compound having a (meth) acryloyl group as a polymerizable group, if the alignment polymer (a-1) is a (meth) acrylic polymer, the affinity is excellent, and even when the bending diameter is small, further improvement in bending resistance that suppresses separation between the polarizing film and the alignment film can be expected. In the present specification, among all structural units forming the polymer main chain, for example, a polymer having the largest proportion of structural units based on a (meth) acrylic acid-based structure, such as a (meth) acrylate unit and a (meth) acrylamide unit, is collectively referred to as a "(meth) acrylic polymer".

The content of the alignment polymer (a-1) in the alignment film forming composition may be appropriately determined depending on the kind of the alignment polymer used, the desired thickness of the alignment film, and the like. The amount of the orientation polymer (a-1) to be used is not particularly limited as long as it can be completely dissolved, but the content (concentration) thereof is preferably 1.0 to 25.0% by mass, more preferably 2.5 to 22.5% by mass, based on the total mass of the orientation film-forming composition. In the composition for forming an alignment film, the number of the alignment polymers (a-1) may be only 1, or 2 or more may be combined, and when 2 or more are contained, the total content thereof is preferably within the above range.

In the present invention, the composition for forming an alignment film contains an alignment polymer (A-1) and a compound (A-2) having an active hydrogen-reactive group (hereinafter also referred to as "compound (A-2)"). The term "active hydrogen-reactive group" as used herein means a group having a carboxyl group (-COOH), a hydroxyl group (-OH), or an amino group (-NH) ₂ ) And a reactive group such as a mercapto group (-SH). When the alignment film is formed from the alignment film-forming composition containing the compound (a-2) having an active hydrogen-reactive group, the adhesion between the base material and the alignment film can be easily controlled, and the effect of suppressing peeling that may occur between the base material and the alignment film when the obtained polarizing element is bent can be enhanced.

Examples of the active hydrogen-reactive group that the compound (a-2) can have include an epoxy group, a glycidyl group, an oxazoline group, a carbodiimide group, an aziridine group, an imide group, an alkoxysilyl group, an isocyanate group, a thioisocyanate group, a maleic anhydride group, and the like. Among them, from the viewpoint of adhesion, the compound (a-2) preferably has at least 1 group selected from an alkoxysilyl group and an isocyanate group, and more preferably has an alkoxysilyl group.

The number of active hydrogen-reactive groups of the compound (A-2) is 1 or more. When a plurality of active hydrogen reactive groups are present, the plurality of active hydrogen reactive groups may be the same or different.

The compound (A-2) preferably has an active hydrogen-containing group in addition to the active hydrogen-reactive group. In the present specification, the "active hydrogen-containing group" refers to a functional group containing active hydrogen. If the compound (a-2) has an active hydrogen-containing group, the adhesion between the alignment film and the polarizing film can be easily controlled, and the effect of suppressing the peeling that may occur between the alignment film and the polarizing film when the obtained polarizing element is bent can be enhanced.

Examples of the active hydrogen-containing group that the compound (a-2) can have include a hydroxyl group, a carboxyl group, an amino group, a mercapto group, a primary amide group, a secondary amide group, and a hydrazide group. Among them, from the viewpoint of reactivity, adhesion, and the like, the compound (a-2) preferably has at least 1 group selected from a hydroxyl group, an amino group, and a mercapto group, and preferably has an amino group or a mercapto group.

The number of active hydrogen-containing groups of the compound (A-2) is 1 or more. When a plurality of active hydrogen-containing groups are present, the plurality of active hydrogen-containing groups may be the same or different.

In one embodiment of the present invention, the compound (A-2) is a silane coupling agent. When a silane coupling agent is used as the compound (a-2), adhesion to a substrate or a polarizing film can be easily controlled, and a polarizing element having excellent bending resistance can be easily obtained. The silane coupling agent may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

As the silane coupling agent, compounds known in the art can be used. Specific examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1, 3-dimethyl-butylidene) propylamine, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, and, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropyldimethoxymethylsilane, and 3-glycidoxypropylethoxydimethylsilane.

The silane coupling agent may be a silicone oligomer type silane coupling agent. Examples of the silicone oligomer type silane coupling agent include a silicone oligomer expressed as a (monomer) oligomer, and include a mercapto-propyl group-containing copolymer such as a 3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, a 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, a 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, and a 3-mercaptopropyltriethoxysilane-tetraethoxysilane copolymer; mercaptomethyl group-containing copolymers such as mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer; 3-glycidoxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-glycidoxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-glycidoxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-glycidoxypropyltriethoxysilane-tetraethoxysilane copolymer, 3-glycidoxypropyl group-containing copolymers such as 3-glycidoxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-glycidoxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-glycidoxypropylmethyldiethoxysilane-tetramethoxysilane copolymer and 3-glycidoxypropylmethyldiethoxysilane-tetraethoxysilane copolymer; 3-methacryloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropyltriethoxysilane-tetraethoxysilane copolymer, methacryloxypropyl-containing copolymers such as 3-methacryloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer; 3-acryloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropyltriethoxysilane-tetraethoxysilane copolymer, acryloxypropyl-containing copolymers such as 3-acryloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer; vinyl group-containing copolymers such as vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, vinylmethyldiethoxysilane-tetraethoxysilane copolymer and the like; amino group-containing copolymers such as 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.

In one embodiment of the present invention, the silane coupling agent preferably has an active hydrogen-containing group. Specifically, the Si element-containing compound having at least 1 functional group selected from an amino group (primary, secondary), a hydroxyl group, and a mercapto group is more preferable, a primary amino group or a secondary amino group is further preferable, and the Si element-containing compound having the at least 1 functional group and at least 1 alkoxysilyl group or silanol group is further preferable. The amino group (primary or secondary), the hydroxyl group, and the mercapto group have polarity, and by appropriately selecting these functional groups, the adhesion between the obtained alignment film and the polarizing film can be controlled, and the bending resistance of the polarizing element can be improved. From this viewpoint, the silane coupling agent is preferably a silane coupling agent having an alkoxysilyl group and the at least 1 functional group. In order to control the reactivity of the silane coupling agent, the functional group may appropriately have a substituent or a protecting group. Examples of the silane coupling agent having a protecting group include KBE-9103P (ketimine type) and X-12-1172ES (aldimine type) manufactured by shin-Etsu chemical industries, Ltd., amino-protected type, and X-12-1056ES (mercapto-protected type).

As the compound (A-2), a commercially available compound can also be used. Examples of such commercially available products include silane coupling agents manufactured by Kjeldahl industry (strain) such as KP321, KP323, KP324, KP326, KP340, KP341, X22-161A, KF6001, KBM-1003, KBE-1003, KBM-303, KBM-402, KBM-403, KBE-403, KBM-1403, KBM-502, KBM-503, KBE-502, KBE-503, KBM-5103, KBM-602, KBM-603, KBM-903, KBE-9103, KBM-573, KBM-575, KBM-9659, KBE-585, KBM-802, KBM-803, KBE-846, KBE-9007, X-12-1172ES, X-12-1154 and KR-519.

The content of the compound (A-2) in the composition for forming an alignment film can be determined appropriately depending on the kind of the compound (A-2), the kind of the substrate, the surface state, the composition of the polarizing film, and the like. In one embodiment of the present invention, the content of the compound (a-2) is preferably 1 part by mass or more and 30 parts by mass or less, more preferably 2.5 parts by mass or more and 25 parts by mass or less, further preferably 5.0 parts by mass or more, and further more preferably 23 parts by mass or less, based on 100 parts by mass of the oriented polymer (a-1). When the content of the compound (a-2) is within the above range, the bending resistance can be further improved while maintaining good optical properties, and an effect of suppressing the peeling of the alignment film from the substrate and/or the polarizing film can be expected even when the bending diameter is small.

The composition for forming an alignment film usually contains a solvent. The solvent is not particularly limited as long as it is a solvent capable of dissolving the components contained in the composition for forming a photo-alignment film, and examples thereof include water; alcohol solvents such as methanol, ethanol, ethylene glycol, isopropanol, 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; chlorinated hydrocarbon solvents such as chloroform and chlorobenzene. These solvents may be used alone, or 2 or more of them may be used in combination.

In the present invention, the composition for forming an alignment film may contain optional components in addition to the above-described components within a range in which the characteristics of the alignment film are not significantly impaired. Examples of such a component include a polymer material and a photosensitizer.

The composition for forming an alignment film can be prepared by, for example, dissolving the alignment polymer (a-1) [ or an oligomer or a monomer capable of forming the alignment polymer (a-1) ], the compound (a-2), and other components used as necessary in a solvent, and can be cured by, for example, a method described below to obtain an alignment film as a cured product thereof.

The thickness of the alignment film is usually in the range of 10nm to 10000nm, preferably 10nm to 2500nm, more preferably 10nm to 1000nm, still more preferably 10nm to 500nm, and particularly preferably 20nm to 250 nm. The thickness of the alignment film can be measured by a laser microscope, a film thickness meter, or the like, and the thickness of each layer such as a polarizing element substrate and a polarizing film is measured in the following manner.

< substrate >

As a substrate for forming the polarizing element of the present invention, a resin film or the like conventionally known in the field of optical films can be used. Examples of the resin forming the substrate include polyolefin resins such as polyethylene and polypropylene; cyclic olefin resins such as norbornene polymers; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; poly (meth) acrylic resins such as (meth) acrylic acid and poly (methyl (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; a polycarbonate-based resin; a polystyrene-based resin; a polyarylate-based resin; a polysulfone-based resin; a polyether sulfone-based resin; a polyamide resin; a polyimide-based resin; a polyether ketone resin; polyphenylene sulfide-based resin; a polyphenylene ether resin; and mixtures thereof, and the like. Among them, from the viewpoint of improvement of bending resistance, versatility, heat resistance and the like, at least 1 selected from the group consisting of vinyl alcohol-based resins, cellulose ester-based resins, cycloolefin-based resins and poly (meth) acrylic resins is preferable.

In the present invention, the substrate preferably has a polar group. Here, in the present specification, the substrate having a polar group means that a polar group is present in the substrate in a state before the alignment film is formed on the substrate. Examples of the polar group include a hydroxyl group, a carboxyl group, and an amino group. Among them, from the viewpoint of being a material for forming the substrate, being easily introduced to the surface of the substrate by surface modification treatment of the substrate, or the like, and having good reactivity with the active hydrogen reactive group of the compound (a-2), the compound (a-2) preferably has at least 1 polar group selected from a hydroxyl group, a carboxyl group, and an amino group, and more preferably has a hydroxyl group. When the base material before formation of the alignment film has the polar group, a bond is generated from a reaction between the polar group present in the base material and the active hydrogen reactive group of the compound (a-2) for forming the alignment film, and the adhesion between the base material and the alignment film is improved, whereby high bending resistance can be imparted to the obtained polarizing element. Therefore, in one embodiment of the present invention, a bond (for example, Si — O bond) resulting from a reaction between the polar group (present in the substrate) and the active hydrogen reactive group (of the compound (a-2)) can be present between the substrate on which the polarizing element of the present invention is formed and the alignment film.

It is preferable that a polar group is present on the surface of the substrate on the side where the alignment film is laminated. Such a substrate may be a substrate obtained by using a resin having a polar group such as a vinyl alcohol resin or a cellulose resin as a material and forming the material into a film, or a substrate obtained by modifying a precursor group contained in a precursor film into a polar group after forming the film (precursor film) by forming a material having a polar group precursor group into a film. Examples of the modification method include plasma treatment under vacuum or atmospheric pressure, corona treatment, laser treatment, ozone treatment, saponification treatment, flame treatment, and the like. The substrate may be one in which a polymer having a polar group is attached to the surface of a substrate containing a material having no polar group or a precursor group thereof, or one in which a polymer having a precursor group of a polar group is attached and then modified to a polar group. The substrate may be obtained by attaching a monomer or a polymer having a polar group to the surface of a substrate containing a material having no polar group or a precursor thereof, and then irradiating the substrate with radiation, plasma, ultraviolet rays, or the like to cause a reaction, thereby performing graft polymerization. Examples of a method for attaching a polymer or a monomer having a polar group or a precursor group of a polar group to the surface of a substrate include a method in which a solution in which the polymer or the monomer is dissolved is applied to the surface of the substrate.

The thickness of the base material is preferably 1 μm or more and 20 μm or less, and more preferably 1 μm or more and 10 μm or less, from the viewpoints of processability, reduction in thickness of the polarizing element, and the like.

< polarizing film >

In the present invention, the polarizing film is a film (layer) having a polarizing function. The polarizing film in the polarizing element of the present invention is preferably a coating layer, and more preferably a polarizing film obtained by curing a composition for forming a polarizing film, which contains a polymerizable liquid crystal compound (B-1), a compound (B-2) having an active hydrogen reactive group, and a dichroic dye (B-3), from the viewpoint of enabling the realization of an ultra-thin type and the securing of bending resistance suitable for a flexible display material.

The polymerizable liquid crystal compound (B-1) contained in the composition for forming a polarizing film is a compound having at least 1 polymerizable group. Here, the polymerizable group means a group capable of participating in a polymerization reaction by an active radical, an acid, or the like generated from a polymerization initiator. Examples of the polymerizable group of the polymerizable liquid crystal compound (B-1) include a vinyl group, a vinyloxy group, a 1-chloroethenyl group, an isopropenyl group, a 4-vinylphenyl group, a (meth) acryloyl group, an epoxyethyl group, and an oxetanyl group. Among these, radical polymerizable groups are preferable, and (meth) acryloyl groups, vinyl groups, and vinyloxy groups are more preferable, and (meth) acryloyl groups are even more preferable. When the polymerizable liquid crystal compound forming the polarizing film has the same functional group (polymerizable group) as the functional group of the compound forming the alignment film, for example, a (meth) acryloyl group, the affinity between the alignment film and the polarizing film becomes high, and excellent bending resistance can be imparted to the obtained polarizing element.

In the present invention, the polymerizable liquid crystal compound (B-1) is preferably a liquid crystal compound exhibiting smectic liquid crystallinity. By using a polymerizable liquid crystal compound exhibiting smectic liquid crystallinity, a polarizing film having a high degree of orientational order can be formed. From the viewpoint of achieving a higher degree of alignment order, the liquid crystal state exhibited by the polymerizable liquid crystal compound (B-1) is more preferably a higher order smectic phase (higher order smectic liquid crystal state). The higher order smectic phase herein means smectic B phase, smectic D phase, smectic E phase, smectic F phase, smectic G phase, smectic H phase, smectic I phase, smectic J phase, smectic K phase and smectic L phase, and among them, smectic B phase, smectic F phase and smectic I phase are more preferable. The liquid crystal may be a thermotropic liquid crystal or a lyotropic liquid crystal, but the thermotropic liquid crystal is preferable in terms of enabling a dense film thickness control. The polymerizable liquid crystal compound (B-1) may be a monomer, an oligomer obtained by polymerizing a polymerizable group, or a polymer.

The polymerizable liquid crystal compound (B-1) is not particularly limited as long as it is a liquid crystal compound having at least 1 polymerizable group, and a known polymerizable liquid crystal compound can be used. Examples of the polymerizable liquid crystal compound include a compound represented by the following formula (B1) (hereinafter, may be referred to as "polymerizable liquid crystal compound (B1)").

U ¹ -V ¹ -W ¹ -(X ¹ -Y ¹ ) _n -X ² -W ² -V ² -U ² (B1)

[ in the formula (B1),

X ¹ and X ² Independently represents a 2-valent aromatic group or a 2-valent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the 2-valent aromatic group or the 2-valent 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 forming the 2-valent aromatic group or the 2-valent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom. Wherein X ¹ And X ² At least 1 of them is a1, 4-phenylene group which may have a substituent or a cyclohexane-1, 4-diyl group which may have a substituent.

Y ¹ Is a single bond or a divalent linking group.

n is 1 to 3, and when n is 2 or more, a plurality of X ¹ May be the same as or different from each other. X ² Can be associated with a plurality of X ¹ Any or all of which may be the same or different. When n is 2 or more, plural Y' s ¹ May be the same as or different from each other. From the viewpoint of liquid crystallinity, 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 Independently of one another, represent a single bond or a divalent linking group.

V ¹ And V ² Independently represent an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and a-CH group forming the alkanediyl group ₂ -may be replaced by-O-, -CO-, -S-or NH-.]

In the polymerizable liquid crystal compound (B1), X ¹ And X ² Independently of one another, it is preferably a1, 4-phenylene group which may have a substituent, or a cyclohexane-1, 4-diyl group which may have a substituent, X ¹ And X ² At least 1 of them is a1, 4-phenylene group which may have a substituent, or a cyclohexane-1, 4-diyl group which may have a substituent, preferably a trans-cyclohexane-1, 4-diyl group. Examples of the optionally substituted 1, 4-phenylene group which may have a substituent or the optionally substituted cyclohexane-1, 4-diyl group which may have a substituent include an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a butyl group and the like, a cyano group, a halogen atom such as a chlorine atom, a fluorine atom and the like. Preferably unsubstituted.

In addition, in the polymerizable liquid crystal compound (B-1), from the viewpoint of easily exhibiting smectic liquid crystallinity, it is preferable that the portion [ hereinafter also referred to as partial structure (B1 ') ] represented by formula (B1') in formula (B1) has an asymmetric structure:

-(X ¹ -Y ¹ ) _n -X ² - (B1’)

[ in the formula, X ¹ 、Y ¹ 、X ² And n each represents the same meaning as above. Angle (c)

Examples of the polymerizable liquid crystal compound (B1) having an asymmetric partial structure (B1 ') include a polymerizable liquid crystal compound having an asymmetric partial structure (B1') in which n is 1 and 1X ¹ And X ² A polymerizable liquid crystal compound (B1) having a structure different from each other. Further, n is 2 or 2Y ¹ Are of the same structure as each other, 2X ¹ Are of the same structure as each other, 1X ² Is equal to the 2X ¹ Polymerizable liquid crystal compounds (B1) having different structures; 2X ¹ And W in ¹ Bonded X ¹ Is X with another party ¹ And X ² Different structure, another party's X ¹ And X ² A polymerizable liquid crystal compound (B1) having the same structure. Further, n is 3,3 of Y ¹ Are of the same structure as each other, 3X ¹ And 1X ² Any 1 of the polymerizable liquid crystal compounds (B1) has a structure different from all the other 3 polymerizable liquid crystal compounds.

Y ¹ Is preferably-CH ₂ CH ₂ -、-CH ₂ O-、-CH ₂ CH ₂ O-, -COO-, -OCOO-, single bond, -N ═ N-, -CR ^a ＝CR ^b -、-C≡C-、-CR ^a N-or-CO-NR ^a -。R ^a And R ^b Independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Y is ¹ More preferably-CH ₂ CH ₂ -, -COO-or single bonds, in the presence of a plurality of Y ¹ In the case of (2), with X ² Bonded Y ¹ More preferably-CH ₂ CH ₂ -or CH ₂ O-is formed. At X ¹ And X ² When all of the same structures are used, it is preferable that 2 or more Y's belonging to different bonding systems exist ¹ . In the presence of a plurality of Y's belonging to mutually different bonding modes ¹ In the case of (2), the smectic liquid crystallinity tends to be easily exhibited because an asymmetric structure is formed.

U ² Is a polymerizable group. U shape ¹ Is a hydrogen atom or a polymerizable group, and is preferably a polymerizable group. U shape ¹ And U ² Preferably, all of them are polymerizable groups, and preferably all of them are radical polymerizable groups. Examples of the polymerizable group include the same groups as those exemplified above as the polymerizable group of the polymerizable liquid crystal compound (B-1). U shape ¹ The polymerizable group shown and U ² The polymerizable groups shown may be different from each other, but are preferably the same kind of group, preferably U ¹ And U ² At least one of (a) and (b) is a (meth) acryloyl group, and more preferably both are (meth) acryloyl groups. The polymerizable group may be in a polymerized state or an unpolymerized state, but is preferably in an unpolymerized state.

As V ¹ And V ² Examples of the alkanediyl group include a methylene group, an ethylene group, a propane-1, 3-diyl group, a butane-1, 4-diyl group, a pentane-1, 5-diyl group, a hexane-1, 6-diyl group, a tert-butyl ether group, a methyl ether group, a butyl ether group, a methyl,Heptane-1, 7-diyl, octane-1, 8-diyl, decane-1, 10-diyl, tetradecane-1, 14-diyl, eicosane-1, 20-diyl, and the like. V ¹ And V ² Preferably an alkanediyl group having 2 to 12 carbon atoms, and more preferably an alkanediyl group having 6 to 12 carbon atoms.

Examples of the substituent optionally contained in the alkanediyl group include a cyano group and a halogen atom, and the alkanediyl group is preferably an unsubstituted, more preferably an unsubstituted, linear alkanediyl group.

W ¹ And W ² Independently of one another, is preferably a single bond, -O-, -S-, -COO-or-OCOO-, more preferably a single bond or-O-.

The structure which easily exhibits smectic liquid crystallinity is preferably a molecular structure having asymmetry in the molecular structure, and specifically, the polymerizable liquid crystal compound (B-1) is more preferably a polymerizable liquid crystal compound having partial structures (B-a) to (B-i) below and exhibiting smectic liquid crystallinity. From the viewpoint of easily exhibiting higher order smectic liquid crystallinity, a partial structure having (B-a), (B-B) or (B-c) is more preferable. In the following (B-a) to (B-i), the bond end (single bond) is represented.

[ solution 6]

Specific examples of the polymerizable liquid crystal compound (B-1) include compounds represented by the formulae (B1-1) to (B1-25). When the polymerizable liquid crystal compound (B-1) has a cyclohexane-1, 4-diyl group, the cyclohexane-1, 4-diyl group is preferably a trans-isomer.

[ solution 7]

[ solution 8]

[ solution 9]

Among them, at least 1 kind selected from the compounds represented by formula (B1-2), formula (B1-3), formula (B1-4), formula (B1-5), formula (B1-6), formula (B1-7), formula (B1-8), formula (B1-13), formula (B1-14), formula (B1-15), formula (B1-16) and formula (B1-17) is preferable. The polymerizable liquid crystal compound (B-1) may be used alone in 1 kind, or may be used in combination with 2 or more kinds.

The polymerizable liquid crystal compound (B-1) can be produced by a known method described in Lub et al, Recl.Trav.Chim.Pays-Bas, 115, 321-328(1996), Japanese patent No. 4719156, and the like.

In the present invention, the composition for forming a polarizing film may contain other polymerizable liquid crystal compounds than the polymerizable liquid crystal compound (B1), but from the viewpoint of obtaining a polarizing film having a high degree of alignment order, the proportion of the polymerizable liquid crystal compound (B1) to the total mass of all the polymerizable liquid crystal compounds contained in the composition for forming a polarizing film is preferably 51 mass% or more, more preferably 70 mass% or more, and still more preferably 90 mass% or more.

When the polarizing film-forming composition contains 2 or more polymerizable liquid crystal compounds, at least 1 of them may be the polymerizable liquid crystal compound (B1), or all of them may be the polymerizable liquid crystal compound (B1). By combining a plurality of polymerizable liquid crystal compounds, the liquid crystal properties can be temporarily maintained even at a temperature not higher than the liquid crystal-to-crystal phase transition temperature.

The content of the polymerizable liquid crystal compound (B-1) in the composition for forming a polarizing film is preferably 40 to 99.9% by mass, more preferably 60 to 99% by mass, and still 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 (B-1) is within the above range, the orientation of the polymerizable liquid crystal compound tends to be high. The solid component of the polarizing film-forming composition means the total amount of components obtained by removing volatile components such as a solvent from the polarizing film-forming composition, and hereinafter, when the "solid component" is referred to in the present specification, the solid component means the component obtained by removing volatile components such as a solvent from the composition to be polarized.

In the present invention, the composition for forming a polarizing film preferably contains a compound (B-2) (hereinafter also referred to as "compound (B-2)") having an active hydrogen-reactive group. The active hydrogen-reactive group of the compound (B-2) may be the same functional group as exemplified as the active hydrogen-reactive group that the compound (A-2) contained in the composition for forming an alignment film can have. Among these, from the viewpoint of reactivity with an active hydrogen-containing group which the compound (a-2) can have, the compound (B-2) preferably has at least 1 group selected from an epoxy group, a glycidyl group, an isocyanate group and an alkoxysilyl group, more preferably has an isocyanate group or an alkoxysilyl group, and still more preferably has an isocyanate group.

The number of active hydrogen-reactive groups of the compound (B-2) is usually 1 to 20, preferably 1 to 10, and in a more preferred embodiment of the present invention, at least 2 active hydrogen-reactive groups are present. When a plurality of active hydrogen reactive groups are present, the plurality of active hydrogen reactive groups may be the same or different.

The compound (B-2) preferably has a polymerizable group in addition to the active hydrogen-reactive group. The polymerizable group may be, for example, a carbon-carbon unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond, and specific examples thereof include a vinyl group, a vinyloxy group, a 1-chloroethenyl group, an isopropenyl group, a 4-vinylphenyl group, a (meth) acryloyl group, an epoxyethyl group, and an oxetanyl group. Among these, in the relationship with the alignment polymer (a-1), (meth) acryloyl is preferable because, if the compound (B-2) has the same functional group (polymerizable group) as the above compound, for example, (meth) acryloyl, the affinity between the alignment film and the polarizing film becomes high, and the bending resistance of the resulting polarizing element can be further improved.

The number of the polymerizable groups of the compound (B-2) is usually 1 to 20, preferably 1 to 10.

In one embodiment of the present invention, the compound (B-2) preferably has at least 1 group selected from an epoxy group, a glycidyl group, an isocyanate group and an alkoxysilyl group as an active hydrogen-reactive group, preferably contains a (meth) acryloyl group as a polymerizable group, and more preferably has 1 or more isocyanate groups and (meth) acryloyl groups each.

Specific examples of the compound (B-2) include compounds having a (meth) acryloyl group (メタ) (アクリル) in Japanese text) and an epoxy group, such as methacryloyloxyglycidyl ether and acryloyloxyglycidyl ether; compounds having a (meth) acryloyl group and an oxetanyl group such as oxetanyl acrylate and oxetanyl methacrylate; compounds having a (meth) acryloyl 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 isopropenyl oxazoline; compounds having a (meth) acryloyl group and an isocyanate group such as isocyanatomethyl acrylate, isocyanatomethyl methacrylate, 2-isocyanatoethyl acrylate, and 2-isocyanatoethyl methacrylate; oligomers of compounds having a (meth) acryloyl group and an alkoxysilyl group, such as 3-acryloyloxypropyltrimethoxysilane and 3-methacryloyloxypropylmethyldimethoxysilane. Further, compounds having a vinyl group, a vinylidene group, and an acid anhydride such as methacrylic anhydride, acrylic anhydride, maleic anhydride, and vinylmaleic anhydride may be mentioned. Among them, methacryloyloxyglycidyl ether, acryloxyglycidyl ether, isocyanatomethyl acrylate, isocyanatomethyl methacrylate, vinyloxazoline, 2-isocyanatoethyl acrylate, 2-isocyanatoethyl methacrylate, 3-acryloxypropyltrimethoxysilane and the oligomers described above are preferable, and isocyanatomethyl acrylate, 2-isocyanatoethyl acrylate, 3-acryloxypropyltrimethoxysilane and the oligomers described above are particularly preferable.

As the compound (B-2), a commercially available product can also be used. Examples of such commercially available products include Laromer (registered trademark) PR9000 (manufactured by BASF Corp.), Karenz AOI (registered trademark) (manufactured by Showa Denko K.K.), Karenz BEI (registered trademark) (manufactured by Showa Denko K.K.), Karenz MOI-EG (registered trademark) (manufactured by Showa Denko K.K.), KBM-5103 (manufactured by shin-Etsu chemical industry Co., Ltd.).

When the polarizing film-forming composition contains the compound (B-2), the compound (B-2) may be the same as or different from the compound (A-2) contained in the alignment film-forming composition.

The content of the compound (B-2) in the polarizing film-forming composition is preferably 0.1 part by mass or more and 12 parts by mass or less, more preferably 0.5 part by mass or more and 10 parts by mass or less, and still more preferably 1 part by mass or more and 10 parts by mass or less, with respect to 100 parts by mass of the polymerizable liquid crystal compound (B-1). When the content of the compound (B-2) is within the above range, the bending resistance of the polarizing element can be easily improved without impairing the orientation of the obtained polarizing film. The compound (B-2) may be used alone or in combination of 2 or more. In the case of using 2 or more compounds (B-2), it is preferable that their total content be within the above range.

In the present invention, the composition for forming a polarizing film usually contains a dichroic dye (B-3). Here, the dichroic dye is a dye having a property that the absorbance of a molecule in the major axis direction is different from the absorbance of a molecule in the minor axis direction. The dichroic dye (B-3) that can be used in the present invention is not particularly limited as long as it has the above-described properties, and may be a dye or a pigment. In addition, 2 or more kinds of dyes or pigments may be used in combination, or a dye and a pigment may be used in combination. The dichroic dye may have polymerizability or liquid crystal properties.

The dichroic dye (B-3) preferably has a maximum absorption wavelength (. lamda.) in the range of 300 to 700nm _MAX ). Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes.

Examples of the azo dye include monoazo dye, disazo dye, trisazo dye, tetraazo dye, stilbene azo dye, and the like, and disazo dye and trisazo dye are preferable, and for example, a compound represented by formula (I) (hereinafter also referred to as "compound (I)") can be mentioned.

K ¹ (-N＝N-K ² ) _p -N＝N-K ³ (I)

[ in the formula (I), K ¹ And K ³ Independently represent an optionally substituted phenyl group, an optionally substituted naphthyl group, an optionally substituted phenyl benzoate group or an optionally substituted 1-valent heterocyclic group. K ² Represents an optionally substituted p-phenylene group, an optionally substituted naphthalene-1, 4-diyl group, an optionally substituted 4, 4' -stilbenylene group or an optionally substituted 2-valent heterocyclic group. 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 as or different from each other. The — N ═ N-bond may be replaced by — C ═ C-, -COO-, -NHCO-, -N ═ CH-bond in the range showing absorption in the visible region.]

Examples of the heterocyclic group having a valence of 1 include groups obtained by removing 1 hydrogen atom from a heterocyclic compound such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole and benzoxazole. The heterocyclic group having a valence of 2 includes a group obtained by removing 2 hydrogen atoms from the above-mentioned heterocyclic compound.

As K ¹ And K ³ In (1) phenyl, naphthyl, phenylbenzoate and heterocyclic group having a valence of 1, and K ² The substituent optionally contained in the p-phenylene group, naphthalene-1, 4-diyl group, 4' -stilbenylene group and 2-valent heterocyclic group in (A) includes an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms and having a polymerizable group, and an alkenyl group having 1 to 4 carbon atoms; alkoxy groups having 1 to 20 carbon atoms such as methoxy, ethoxy, butoxy and the like; an alkoxy group having 1 to 20 carbon atoms and having a polymerizable group; a C1-4 fluoroalkyl group such as a trifluoromethyl group; a cyano group; a nitro group; a halogen atom; substituted or unsubstituted amino group such as amino group, diethylamino group, pyrrolidinyl group and the like(the substituted amino group means an amino group having 1 or 2 alkyl groups having 1 to 6 carbon atoms, an amino group having 1 or 2 alkyl groups having 1 to 6 carbon atoms and having a polymerizable group, or an amino group in which 2 substituted alkyl groups are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms-the unsubstituted amino group is-NH ₂ . ) And the like. Examples of the polymerizable group include a (meth) acryloyl group, a (meth) acryloyloxy group, and the like.

Among the compounds (I), preferred are compounds represented by any of the following formulae (I-1) to (I-8).

[ solution 10]

[ formulae (I-1) to (I-8),

B ¹ ～B ³⁰ independently represents 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 the substituted amino group and the unsubstituted amino group are as described above), a chlorine atom or a trifluoromethyl group.

n1 to n4 each independently represents an integer of 0 to 3.

When n1 is 2 or more, a plurality of B ² May be the same as, or different from,

when n2 is 2 or more, a plurality of B ⁶ May be the same as, or different from,

when n3 is 2 or more, a plurality of B ⁹ May be the same as, or different from,

when n4 is 2 or more, a plurality of B ¹⁴ May be the same as or different from each other.]

As the anthraquinone dye, a compound represented by the formula (I-9) is preferable.

[ solution 11]

[ in the formula (I-9),

R ¹ ～R ⁸ independently of each other, a hydrogen atom, -R ^x 、-NH ₂ 、-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.]

As the oxazinone (oxazone) pigment, a compound represented by the formula (I-10) is preferred.

[ solution 12]

[ in the formula (I-10),

R ⁹ ～R ¹⁵ independently of each other, a hydrogen atom, -R ^x 、-NH ₂ 、-NHR ^x 、-NR ^x ₂ 、-SR ^x Or a halogen atom.

As the acridine pigment, a compound represented by the formula (I-11) is preferable.

[ solution 13]

[ in the formula (I-11),

R ¹⁶ ～R ²³ independently of each other, a hydrogen atom, -R ^x 、-NH ₂ 、-NHR ^x 、-NR ^x ₂ 、-SR ^x Or a halogen atom.

In the formula (I-9), the formula (I-10) and the formula (I-11), as R ^x Examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, propyl, butyl, pentyl and hexyl groups, and those having 6 to 12 carbon atomsExamples of the aryl group include a phenyl group, a tolyl group, a xylyl group, and a naphthyl group.

As the cyanine dye, a compound represented by the formula (I-12) and a compound represented by the formula (I-13) are preferable.

[ solution 14]

[ in the formula (I-12),

D ¹ and D ² Independently represent a group represented by any one of the formulae (I-12a) to (I-12 d).

[ chemical 15]

n5 represents an integer of 1 to 3. ]

[ solution 16]

[ in the formula (I-13),

D ³ and D ⁴ Independently represent a group represented by any one of the formulae (I-13a) to (1-13 h).

[ solution 17]

n6 represents an integer of 1 to 3. ]

Among these dichroic dyes, azo dyes are suitable for producing polarizing films having excellent polarizing properties because of their high linearity. Therefore, in one embodiment of the present invention, the dichroic dye (B-3) contained in the polarizing film-forming composition for forming a polarizing film is preferably an azo dye.

In the present invention, the weight average molecular weight of the dichroic dye (B-3) is usually 300 to 2000, preferably 400 to 1000.

In one embodiment of the present invention, the dichroic dye (B-3) contained in the polarizing film-forming composition forming the polarizing film is preferably hydrophobic. When the dichroic dye (B-3) is hydrophobic, the compatibility between the dichroic dye (B-3) and the polymerizable liquid crystal compound (B-1) is improved, and the dichroic dye (B-3) and the polymerizable liquid crystal compound (B-1) form a uniform phase state, whereby a polarizing film having a high degree of orientation order can be obtained. In the present invention, the hydrophobic dichroic dye means a dye having a solubility of 1g or less with respect to 100g of water at 25 ℃.

The content of the dichroic dye (B-3) in the polarizing film-forming composition may be appropriately determined depending on the kind of the dichroic dye used, and is preferably 0.1 to 50 parts by mass, more preferably 0.1 to 20 parts by mass, and still more preferably 0.1 to 12 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound. When the content of the dichroic dye (B-3) is within the above range, the orientation of the polymerizable liquid crystal compound is not easily disturbed, and a polarizing film having a high degree of orientation order can be obtained.

In the present invention, the composition for forming a polarizing film may contain a polymerization initiator. The polymerization initiator is a compound capable of initiating the polymerization reaction of the polymerizable liquid crystal compound (B-1), and is preferably a photopolymerization initiator in view of being capable of initiating the polymerization reaction under a lower temperature condition. Specifically, there may be mentioned photopolymerization initiators capable of generating active radicals or acids by the action of light, and among them, photopolymerization initiators capable of generating radicals by the action of light are preferred. The polymerization initiator may be used alone or in combination of two or more.

As the photopolymerization initiator, a known photopolymerization initiator can be used, and examples of the photopolymerization initiator that generates active radicals include a self-cleavage type photopolymerization initiator and a hydrogen abstraction type photopolymerization initiator.

As the self-cleavage type photopolymerization initiator, a self-cleavage type benzoin-based compound, an acetophenone-based compound, a hydroxyacetophenone-based compound, an α -aminoacetophenone-based compound, an oxime ester-based compound, an acylphosphine oxide-based compound, an azo-based compound, or the like can be used. Further, as the hydrogen abstraction type photopolymerization initiator, a hydrogen abstraction type benzophenone-based compound, benzoin ether-based compound, benzil ketal-based compound, dibenzosuberone-based compound, anthraquinone-based compound, xanthenone-based compound, thioxanthone-based compound, halogenated acetophenone-based compound, dialkoxyacetophenone-based compound, halogenated bisimidazole-based compound, halogenated triazine-based compound, and the like can be used.

As the photopolymerization initiator generating an acid, iodonium salts, sulfonium salts, and the like can be used.

Among them, from the viewpoint of preventing the dissolution of the dye, a reaction at a low temperature is preferable, and from the viewpoint of reaction efficiency at a low temperature, a self-cleavage type photopolymerization initiator is preferable, and particularly, an acetophenone-based compound, a hydroxyacetophenone-based compound, an α -aminoacetophenone-based compound, and an oxime ester-based compound are preferable.

Specific examples of the photopolymerization initiator include the following photopolymerization initiators.

Benzoin-based compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether;

hydroxyacetophenone-based compounds such as oligomers of 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1, 2-diphenyl-2, 2-dimethoxy-1-ethanone, 2-hydroxy-2-methyl-1- [4- (2-hydroxyethoxy) phenyl ] -1-propanone, 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl ] -1-propanone;

α -aminoacetophenone-based compounds such as 2-methyl-2-morpholinophenyl-1- (4-methylthiophenyl) -1-propanone and 2-dimethylamino-2-benzyl-1- (4-morpholinophenyl) -1-butanone;

oxime ester compounds such as 1- [4- (phenylthio) ]1, 2-octanedione 2- (O-benzoyloxime) and 1- [ 9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl ] ethanone 1- (O-acetyloxime);

acylphosphine oxide-based compounds such as 2, 4, 6-trimethylbenzoyldiphenylphosphine oxide and bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide;

benzophenone compounds such as benzophenone, methyl benzoylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4 ' -methyldiphenyl sulfide, 3 ', 4, 4 ' -tetrakis (t-butylperoxycarbonyl) benzophenone, and 2, 4, 6-trimethylbenzophenone;

dialkoxyacetophenone-based 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) vinyl ] -1, 3, 5-triazine, 2, 4-bis (trichloromethyl) -6- [ 2- (furan-2-yl) vinyl ] -1, 3, 5-triazine Triazine compounds such as (E) -2-methylphenyl) vinyl ] -1, 3, 5-triazine and (E) -2, 4-bis (trichloromethyl) -6- [ 2- (3, 4-dimethoxyphenyl) vinyl ] -1, 3, 5-triazine. The photopolymerization initiator may be appropriately selected from the above photopolymerization initiators in relation to the polymerizable liquid crystal compound (B-1) and the compound (B-2) contained in the polarizing film-forming composition.

Further, a commercially available photopolymerization initiator may be used. Examples of commercially available polymerization initiators include Irgacure (registered trademark) 907, 184, 651, 819, 250, 369, 379, 127, 754, OXE01, OXE02, OXE03 (manufactured by BASF); omnirad BCIM, Escapure 1001M, Escapure KIP160 (manufactured by IDM Resins B.V.); seikuol (registered trademark) BZ, Z and BEE (manufactured by Seiko chemical Co., Ltd.); kayacure (registered trademark) BP100, and UVI-6992 (manufactured by Dow Chemical corporation); adeka Optomer SP-152, N-1717, N-1919, SP-170, Adeka Arkls NCI-831, Adeka Arkls NCI-930 (manufactured by ADEKA Co., Ltd.); TAZ-A and TAZ-PP (manufactured by Siber Hegner, Japan); and TAZ-104 (manufactured by Kabushiki Kaisha, Kagaku Co., Ltd.).

The content of the polymerization initiator in the polarizing film-forming composition for forming a polarizing film is preferably 1 to 10 parts by mass, more preferably 1 to 8 parts by mass, even more preferably 2 to 8 parts by mass, and particularly preferably 4 to 8 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound (B-1). When the content of the polymerization initiator is within the above range, the polymerization reaction of the polymerizable liquid crystal compound can proceed without largely disturbing the orientation of the polymerizable liquid crystal compound.

The composition for forming a polarizing film may further contain a photosensitizer. By using the photosensitizer, the polymerization reaction of the polymerizable liquid crystal compound (B-1) can be further promoted. Examples of the photosensitizer include xanthone compounds such as xanthone and thioxanthone (for example, 2, 4-diethylthioxanthone and 2-isopropylthioxanthone); anthracene compounds such as anthracene and alkoxy-containing anthracene (e.g., dibutoxyanthracene); phenothiazine, rubrene, and the like. The photosensitizers may be used singly or in combination of 2 or more.

When the composition for forming a polarizing film contains a photosensitizer, the content thereof may be determined appropriately depending on the kind and amount of the polymerization initiator and the polymerizable liquid crystal compound (B-1), and is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 10 parts by mass, and still more preferably 0.5 to 8 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound (B-1).

In addition, the polarizing film-forming composition may contain a leveling agent. The leveling agent has a function of adjusting the fluidity of the composition for forming a polarizing film and flattening a coating film obtained by applying the composition for forming a polarizing film, and specifically includes a surfactant. The leveling agent is preferably at least 1 selected from 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 agent may be used alone or in combination of 2 or more.

Examples of the leveling agent containing a polyacrylate compound as a main component include "BYK-350", "BYK-352", "BYK-353", "BYK-354", "BYK-355", "BYK-358N", "BYK-361N", "BYK-380", "BYK-381", and "BYK-392" (BYK Chemie).

Examples of the leveling agent containing a fluorine atom-containing compound as a main component include "Megafac (registered trademark) R-08", "Megafac R-30", "Megafac R-90", "Megafac F-410", "Megafac F-411", "Megafac F-443", "Megafac F-445", "Megafac F-470", "Megafac F-471", "Megafac F-477", "Megafac F-479", "Megafac F-482" and "Megafac F-483" (available from DIC corporation)); "Surflon (registered trademark) S-381", "Surflon S-382", "Surflon S-383", "Surflon S-393", "Surflon SC-101", "Surflon SC-105", "KH-40" and "SA-100" (AGC SEIMI CHEMICAL (strain)); "E1830", "E5844" (strain) DAIKIN FINE CHEMICAL institute); "Eftop EF 301", "Eftop EF 303", "Eftop EF 351" and "Eftop EF 352" (Mitsubishi Material electronics Kabushiki Kaisha).

When the composition for forming a polarizing film contains a leveling agent, the content thereof is preferably 0.05 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, per 100 parts by mass of the polymerizable liquid crystal compound (B-1). When the content of the leveling agent is within the above range, the polymerizable liquid crystal compound (B-1) is easily aligned, and unevenness is less likely to occur, and a smoother polarizing film tends to be obtained.

The composition for forming a polarizing film may contain other additives besides the photosensitizer and the leveling agent. Examples of the other additives include colorants such as antioxidants, mold release agents, stabilizers, and bluing agents, flame retardants, and lubricants. When the polarizing film-forming composition contains other additives, the content of the other additives is preferably more than 0% and 20% by mass or less, more preferably more than 0% and 10% by mass or less, relative to the solid content of the polarizing film-forming composition.

The composition for forming a polarizing film can be produced by a conventionally known method for producing a composition for forming a polarizing film, and can be produced, for example, by mixing and stirring the polymerizable liquid crystal compound (B-1), the compound (B-2), the dichroic dye (B-3), and, if necessary, the polymerization initiator and the above-mentioned additives. In addition, since the compound exhibiting smectic liquid crystallinity has a high viscosity, the viscosity can be adjusted by adding a solvent to the composition for forming a polarizing film, in order to improve the coatability of the composition for forming a polarizing film and facilitate the formation of the polarizing film.

The solvent used in the composition for forming a polarizing film can be appropriately selected depending on the solubility of the polymerizable liquid crystal compound (B-1), the compound (B-2) and the dichroic dye (B-3) to be used. Specifically, the same solvents as those exemplified above as solvents that can be used in the composition for forming an alignment film can be cited. The solvent may be used alone in 1 kind, or may be used in combination of 2 or more kinds. The content of the solvent is preferably 100 to 1900 parts by mass, more preferably 150 to 900 parts by mass, and still more preferably 180 to 600 parts by mass, per 100 parts by mass of the solid content of the composition for forming a polarizing film.

The polarizing film can be obtained by curing the composition for forming a polarizing film, for example, in accordance with the method described later. For example, a polymerizable liquid crystal compound (B-1) such as the polymerizable liquid crystal compound (B1) can form a polarizing film by photopolymerization while maintaining a liquid crystal state of a liquid crystal phase, particularly a smectic phase, preferably a higher order smectic phase. The polarizing film obtained by polymerization while maintaining the liquid crystal state of the smectic phase is accompanied by the action of a dichroic dye, and has an advantage of higher polarizing performance as compared with a conventional guest-host polarizing film, that is, a polarizing film formed in a nematic liquid crystal state. Further, the polarizing film has an advantage of being excellent in strength as compared with a polarizing film coated with only a dichroic dye or a lyotropic liquid crystal.

In the present invention, the polarizing film is preferably a polarizing plate having a high degree of orientation order. The polarizing plate having a high degree of orientation order can obtain bragg peaks derived from a high-order structure such as a hexagonal phase or a crystal phase in X-ray diffraction measurement. The bragg peak is a peak derived from a plane periodic structure of molecular orientation. Thus, the polarizing film forming the polarizing element of the present invention preferably shows bragg peaks in X-ray diffraction measurement. That is, in the polarizing film forming the polarizing element of the present invention, it is preferable to orient the polymerizable liquid crystal compound (B-1) or a polymer thereof so that the polarizing film shows a bragg peak in X-ray diffraction measurement, and it is more preferable to perform "horizontal orientation" in which molecules of the polymerizable liquid crystal compound (B-1) are oriented in a direction of absorbing light. In the present invention, a polarizing plate having a circumferential period interval of molecular orientation of 3.0 to 6.0 is preferable. The high degree of alignment order of the Bragg peak can be achieved by controlling the types and amounts of the polymerizable liquid crystal compound (B-1), the compound (B-2) and the dichroic dye (B-3) to be used, and the types and amounts of the polymerization initiator.

The thickness of the polarizing film is suitably selected depending on the display device to be used, and is preferably 0.1 to 10 μm, more preferably 0.3 to 9 μm, and still more preferably 0.5 to 8 μm. When the film thickness of the polarizing film is equal to or more than the above-described lower limit, it is easy to prevent the failure to obtain necessary light absorption, and when the film thickness is equal to or less than the above-described upper limit, it is easy to suppress the occurrence of alignment defects due to a decrease in the alignment regulating force of the alignment film.

In one embodiment of the present invention, the polarizing element may include an overcoat layer on the side of the polarizing film opposite to the orientation film. The overcoat layer can function, for example, to prevent diffusion of the dichroic dye and damage to the polarizing film. The overcoat layer is not particularly limited as long as it can impart a desired function to the polarizing element, and examples thereof include a layer formed from a resin composition containing a water-soluble polymer, a layer formed from a curable composition containing an active energy ray-curable resin, and the like. Among them, since the water-soluble polymer generally has a polarity greatly different from that of the dichroic dye, the dichroic dye has an excellent diffusion preventing effect, and an improvement in bending resistance due to a bond formation with an active hydrogen reactive group of the compound (B-2) contained in the polarizing film-forming composition can be expected, and therefore, in one embodiment of the present invention, the overcoat layer is preferably a layer formed of a resin composition containing a water-soluble polymer.

Examples of the water-soluble polymer capable of forming the overcoat layer include polyacrylamide polymers; polyvinyl alcohol, and vinyl alcohol polymers such as ethylene-vinyl alcohol copolymers, (meth) acrylic acid or anhydride thereof-vinyl alcohol copolymers; a carboxyvinyl polymer; polyvinylpyrrolidone; starches; sodium alginate; or a polyethylene oxide polymer. These polymers may be used alone, or 2 or more of them may be used in combination.

In the case where the overcoat layer is a layer formed of a resin composition containing a water-soluble polymer (hereinafter also referred to as "water-soluble polymer-containing resin composition"), the content of the water-soluble polymer in the layer is preferably 75% by mass or more, more preferably 80% by mass or more, and still more preferably 85% by mass or more.

In the case where the overcoat layer is a layer formed of a resin composition containing a water-soluble polymer, a crosslinked structure can be introduced by using a crosslinking agent in order to improve the denseness of the layer. As such a crosslinking agent, for example, a water-soluble additive such as glyoxylate or the like, a crosslinking agent, and a crosslinking agent can be used, and for the purpose of imparting water resistance, a hydrophobic crosslinking agent such as an isocyanate-based crosslinking agent, a polyaldehyde-based crosslinking agent such as glyoxal or a glyoxal derivative, or a metal compound-based crosslinking agent such as zirconium chloride or titanium lactate can be used.

When a crosslinking agent is used, the amount of the crosslinking agent to be added may be appropriately determined depending on the kind of the crosslinking agent to be used. For example, the amount of the water-soluble polymer is 0.1 to 100 parts by mass, preferably 1 to 50 parts by mass, and more preferably 10 to 30 parts by mass, based on 100 parts by mass of the water-soluble polymer. When the content of the crosslinking agent is in the above range, the overcoat layer becomes dense, and the effect of shielding the dichroic dye (B-3) in the polarizing film is easily enhanced.

The resin composition containing a water-soluble polymer capable of forming an overcoat layer is generally prepared in the form of a solution in which the water-soluble polymer is dissolved in a solvent. The solvent may be selected depending on the water-soluble polymer to be used, and typically, water, alcohol, a miscible material of water and alcohol, and the like are mentioned, with water being preferred.

The solid content concentration of the water-soluble polymer-containing resin composition obtained by adding a solvent to a component forming the overcoat layer such as a water-soluble polymer and a crosslinking agent is preferably 1 to 50% by mass, more preferably 2 to 30% by mass, and still more preferably 3 to 15% by mass. When the solid content concentration of the resin composition containing a water-soluble polymer is within the above range, the viscosity of the composition is lowered, and thus the coating property and the handling property are improved.

The resin composition containing a water-soluble polymer may contain other components such as additives in addition to the water-soluble polymer, a crosslinking agent, and a solvent such as water. Examples of such other components include a preservative and a leveling agent. When the water-soluble polymer-containing resin composition contains other components such as additives, the amount thereof is preferably 10% by mass or less, more preferably 5% by mass or less, based on the solid content of the resin composition.

The resin composition containing a water-soluble polymer thus prepared is cured, for example, according to a method described later by dissolving the essential components such as a water-soluble polymer and a crosslinking agent in a solvent, whereby an overcoat layer can be formed.

The thickness of the overcoat layer may be appropriately selected depending on the material forming the overcoat layer, the display device to be applied. The thickness of the overcoat layer may be, for example, 0.1 to 5.0 μm, preferably 0.5 to 3.0. mu.m.

The polarizing element of the present invention can be manufactured, for example, by a method including the steps of:

Hereinafter, this manufacturing method is also referred to as "the method for manufacturing a polarizing element of the present invention".

In the step (1), examples of the method for applying the composition for forming an alignment film to a substrate include known methods such as a coating method such as a spin coating method, an extrusion method, a gravure coating method, a die coating method, a bar coating method, and a coater method, and a printing method such as a flexographic method.

The solvent in the coating film of the obtained composition for forming an alignment film is dried, and the active hydrogen reactive group of the compound (a-2) is reacted with the polar group of the substrate, whereby a bond derived from these functional groups can be formed. This ensures higher adhesion between the substrate and the alignment film. Examples of the drying method for removing the solvent contained in the coating film of the composition for forming an alignment film include a natural drying method, a forced air drying method, a heat drying method, a reduced pressure drying method, and the like. Among them, from the viewpoint of promoting the reaction between the active hydrogen reactive group of the compound (a-2) and the polar group of the base material and the viewpoint of productivity, heat drying is preferable. The conditions for the heat drying may be appropriately determined depending on the composition of the composition for forming an alignment film, the type of the substrate, the thickness of the alignment film, and the like. For example, the heating temperature may be 50 to 200 ℃, preferably 100 to 150 ℃. The drying time is usually 20 seconds to 10 minutes, preferably 30 seconds to 5 minutes.

When the alignment film is a rubbing alignment film, a dry coating film of the alignment film-forming composition obtained in step (1) is subjected to a rubbing treatment in step (2), whereby a rubbing alignment film can be obtained. As the rubbing treatment method, for example, a method of bringing a dried coating film of the composition for forming an alignment film obtained in the step (1) into contact with a rotating rubbing roll around which a rubbing cloth is wound can be mentioned.

When the alignment film is a photo-alignment film, the dry coating film of the composition for forming an alignment film obtained in step (1) is irradiated with light in step (2), whereby a photo-alignment film can be obtained. By selecting the polarization direction of the irradiated polarized light, the direction of the orientation restriction force can be arbitrarily controlled.

The method of irradiating polarized light may be a method of directly irradiating a dried coating film of the alignment film forming composition formed on the substrate with polarized light, or a method of irradiating the substrate with polarized light while transmitting the polarized light. The polarized light is preferably substantially parallel light. The wavelength of the polarized light to be irradiated may be a wavelength in a wavelength region in which the photoreactive group of the photo-alignment polymer can absorb light energy. Specifically, UV (ultraviolet) light having a wavelength of 250 to 400nm is preferable. Examples of the light source used for the polarized light irradiation include a xenon lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, and an ultraviolet laser such as KrF and ArF, and more preferably a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp. These lamps are preferable because of their high emission intensity of ultraviolet rays having a wavelength of 313 nm. Polarized UV can be irradiated by irradiating light from the light source after passing through an appropriate polarizing plate. As the polarizing plate, a polarizing prism such as a polarizing filter, a glan thomson prism, or a glan taylor prism, or a wire grid type polarizing plate can be used.

When the rubbing treatment or the polarized light irradiation is performed, a plurality of regions (patterns) having different liquid crystal alignment directions may be formed by masking.

The method of applying the composition for forming a polarizing film on the alignment film in the step (3) includes a method similar to the method of applying the composition for forming an alignment film on the substrate. The resultant coating film of the composition for forming a polarizing film can be dried to form a dry coating film by removing the solvent by drying or the like under the condition that the polymerizable liquid crystal compound (B-1) contained in the coating film is not polymerized. The method of drying may be the same as the method of drying the coating film of the composition for forming an alignment film. In the case where the compound (a-2) in the alignment film-forming composition is a compound having an active hydrogen-containing group, the active hydrogen-containing group of the compound (a-2) may be reacted with the active hydrogen-reactive group of the compound (B-2) to form a bond derived from these functional groups while drying the solvent in the coating film of the polarizing film-forming composition. This ensures higher adhesion between the alignment film and the polarizing film.

Further, in order to change the polymerizable liquid crystal compound (B-1) into a liquid phase, the temperature is raised to a temperature at which the polymerizable liquid crystal compound (B-1) changes into a liquid phase or higher, and then the temperature is lowered to change the polymerizable liquid crystal compound (B-1) into a liquid phase (smectic phase). This phase transition may be performed after the solvent in the coating film is removed in step (3), or may be performed simultaneously with the removal of the solvent.

In the step (4), the polymerizable liquid crystal compound (B-1) is polymerized while maintaining the liquid crystal state of the polymerizable liquid crystal compound (B-1), whereby a polarizing film can be formed as a cured product of the polarizing film-forming composition. The polymerization method is preferably a photopolymerization method. In photopolymerization, the light to be irradiated to the dried coating film can be appropriately selected depending on the type of the polymerizable liquid crystal compound (B-1) contained in the dried coating film (particularly, the type of the polymerizable group contained in the polymerizable liquid crystal compound (B-1)), the type of the polymerization initiator, the amount of the polymerization initiator, and the like. Examples of the light source include the same light sources as those exemplified in the formation of the photo-alignment film. The irradiation energy is preferably such that the irradiation intensity in a wavelength region effective for activation of the polymerization initiator is 10 to 5000mJ/cm ² The mode of (1) is more preferably 100 to 2000mJ/cm ² . It is preferable to select the types of the polymerizable liquid crystal compound (B-1) and the polymerization initiator for forming the composition for forming a polarizing film so as to be photopolymerizable by ultraviolet light. In addition, the polymerization temperature can also be controlled by irradiating light while cooling the dried coating film by an appropriate cooling mechanism at the time of polymerization. In photopolymerization, a polarizing film subjected to a pattern treatment can be obtained by performing masking, development, or the like.

The method for producing a polarizing element of the present invention may further include a step of forming an overcoat layer on the polarizing film formed in step (4).

For example, when the overcoat layer is formed of a resin composition containing a water-soluble polymer, the overcoat layer can be obtained by applying the resin composition containing a water-soluble polymer to the surface of the polarizing film opposite to the orientation film, drying and removing the solvent in the coating film, and curing the coating film.

The method for applying the water-soluble polymer-containing resin composition is not particularly limited, and examples thereof include the same methods as the method for applying the composition for forming an alignment film.

The drying temperature, time, and the like for forming the overcoat layer from the coating film of the water-soluble polymer-containing resin composition are not particularly limited, and may be appropriately determined depending on the composition of the water-soluble polymer-containing resin composition to be used, and the like. The drying treatment may be performed by blowing hot air or the like, and the temperature is usually 40 to 100 ℃, preferably 60 to 100 ℃. The drying time is usually 10 to 600 seconds.

The polarizing element of the present invention is configured to have high bending resistance and to be easily made thinner, and for example, the total thickness of the polarizing element formed of a substrate, an alignment film, and a polarizing film can be set to 1.0 to 10.0 μm.

The polarizing element of the present invention can be used for various display devices.

The display device is a device having a display element, and includes a light-emitting element or a light-emitting device as a light-emitting source. Examples of the display device include a liquid crystal display device, an organic Electroluminescence (EL) display device, an inorganic Electroluminescence (EL) display device, a touch panel display device, an electron emission display device (e.g., an electric field emission display device (FED), a surface field emission display device (SED)), electronic paper (a display device using electronic ink, an electrophoretic element, a plasma display device, a projection display device (e.g., a Grating Light Valve (GLV) display device, a display device having a Digital Micromirror Device (DMD)), a piezoelectric ceramic display, and the like; the liquid crystal display device may include any display device such as a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, a reflective liquid crystal display device, a direct-viewing liquid crystal display device, and a projection liquid crystal display device; these display devices may be display devices that display two-dimensional images, a stereoscopic display device that displays a three-dimensional image may be used. In particular, the polarizing element of the present invention can be suitably used for an organic Electroluminescence (EL) display device and an inorganic Electroluminescence (EL) display device, and can also be suitably used for a liquid crystal display device and a touch panel display device.

The polarizing element of the present invention is suitably usable for a flat panel display device, has high bending resistance, and can be made to be slim, and therefore is suitable for a flexible display material. The flexible display material of the present invention can be suitably incorporated into a flexible image display device.

Examples

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 the following examples. In the examples, "%" and "part(s)" are% by mass and part(s) by mass, respectively, unless otherwise specified.

1. Example 1

(1) Preparation of composition for forming photo-alignment film

Synthesis example 1: synthesis of orientation Polymer 1

The alignment polymer 1 includes the following structural units.

[ orientation Polymer 1]

[ solution 18]

[ Synthesis protocol of orientation Polymer 1]

[ solution 19]

[ Synthesis of Compound (a1-1-1 ]

50g (258mmol) of ferulic acid was dissolved in 360g of methanol. To the resulting solution, 10g of sulfuric acid was added at room temperature, and the mixture was heated until the solvent refluxed, followed by reaction under reflux for 2 hours. After the resulting reaction solution was cooled, 150g of ice and 150g of water were added. The supernatant was removed by decantation, and 150g of water at 5 ℃ was added thereto to crystallize the crystals. The resulting white crystals were filtered. The filtered white crystals were washed with 1M aqueous sodium hydrogencarbonate solution and water and then dried under vacuum to obtain 22.2g of compound (a 1-1-1). The yield was 83% based on ferulic acid.

[ Synthesis of Compound (b1-1-1 ]

Compound (a1-1-1) (25 g (120mmol) was dissolved in dimethylacetamide (250 g). To the resulting solution were added 33.19g (240mmol) of potassium carbonate and 1.99g (12mmol) of potassium iodide. 6-Chlorohexanol was added dropwise to the resulting dispersion, and the mixture was stirred at room temperature for 1 hour and then at 70 ℃ for 8 hours. The resulting reaction solution was filtered to remove insoluble matter. To the filtrate, 200g of methyl isobutyl ketone and 300g of water were added, followed by stirring, standing, and separating the liquid, followed by recovering the organic layer. 200g of water was added to the collected organic layer, and the mixture was stirred, allowed to stand, and separated, and the series of water washing operations was repeated 2 times. The solvent was removed from the recovered organic layer by distillation under reduced pressure using an evaporator to obtain a crude product of compound (b 1-1-1).

[ Synthesis of Compound (c1-1-1 ]

The entire amount of the crude product of the compound (b1-1-1) was dissolved in 185g of ethanol. To the resulting solution were added 92g of water and 14.41g (360mmol) of sodium hydroxide and stirred at 80 ℃ for 1 hour. After the reaction solution was cooled to about 3 ℃, 2M aqueous hydrochloric acid was added while keeping the temperature at 5 ℃ or lower to adjust the pH to 2. The white precipitate obtained by the acid precipitation was collected by filtration, washed 2 times with a mixed solution of 100g of water and 80g of methanol, and then vacuum-dried to obtain 30.4g of compound (c 1-1-1). The yield based on the compound (a1-1-1) was 86%.

[ Synthesis of Compound (M1-1-1) ]

27.46g (93mmol) of compound (c1-1-1) was dissolved in 280g of chloroform. To the resulting solution were added 2.06g of BHT (di-t-butyl-hydroxytoluene) and 37.73g (373mmol) of triethylamine as a polymerization inhibitor, and the mixture was stirred in an ice bath. To the reaction solution, 29.26g (260mmol) of methacryloyl chloride was added dropwise, and the mixture was stirred at 5 ℃ or lower for 5 hours. To the resulting reaction solution were added 5.7g of dimethylaminopyridine and 190g of water, and the mixture was stirred at room temperature for 12 hours. After standing, the organic layer was collected, 100g of a 2N aqueous hydrochloric acid solution was added to the organic layer, and the series of washing operations was repeated 2 times with stirring, standing, and liquid separation. The organic layer was recovered, and 300g of n-heptane was added thereto to collect the precipitated crystals by filtration. After washing 2 times with a mixed solvent containing 100g of water and 80g of methanol, vacuum drying was performed to obtain 22.0g of compound (M1-1-1). The yield based on the compound (c1-1-1) was 65%.

[ Synthesis of orientation Polymer 1]

To a Schlenk tube were added 1.00g (2.76mmol) of the compound (M1-1-1) and 10g of tetrahydrofuran, and after deoxygenation, 2.27mg of Azobisisobutyronitrile (AIBN) was added while passing nitrogen gas through the tube, and the mixture was stirred at 60 ℃ for 72 hours. The resulting reaction solution was added to 200g of toluene. The precipitate was collected by filtration, washed with heptane, and vacuum-dried, whereby 0.75g of oriented polymer 1 was obtained. The yield based on the compound (M1-1-1) was 75%. The molecular weight of the obtained oriented polymer 1 was measured by GPC and showed a number average molecular weight of 28200, a weight average molecular weight of about 51300, Mw/Mn of 1.82, and a monomer content of 0.5%.

Synthesis examples 2 and 3: synthesis of oriented Polymer 2 and oriented Polymer 3

The following structure of the alignment polymer 2 and alignment polymer 3 was synthesized by the method described in Macromolecules, vol.39, No.26, 9357 (2006). In the following structural formulae, the parenthesized numerical values indicate the mole fractions of the respective structural units with respect to the entire structural units of the alignment polymers 2 and 3.

[ solution 20]

[ solution 21]

The weight average molecular weight of the oriented polymer 2 was about 100000, and the weight average molecular weight of the oriented polymer 3 was about 90000.

Synthesis example 4: synthesis of alignment Polymer 4

The following structure of the oriented polymer 4 was synthesized according to the synthesis methods of the oriented polymer 2 and the oriented polymer 3. In the following structural formulae, the numerical values in parentheses indicate the mole fractions of the respective structural units with respect to the total structural units of the alignment polymer 4.

[ solution 22]

The weight average molecular weight of the alignment polymer 4 was about 95000.

Production of composition for Forming photo-alignment film

The oriented polymer solution 1 was obtained by mixing 2 parts of the oriented polymer (oriented polymer 1) produced in the above-described manner with 98 parts of o-xylene and stirring the mixture at 80 ℃ for 1 hour. Then, to the obtained alignment polymer solution 1, 3-aminopropyltriethoxysilane (trade name: KBE-903, manufactured by shin-Etsu chemical Co., Ltd.) was added as a compound (A-2) in an amount of 1.0 part per 100 parts of the alignment polymer, followed by mixing to obtain a composition for forming a photo-alignment film.

(2) Production of polarizing film-Forming composition

The following components were mixed and stirred at 80 ℃ for 1 hour to obtain a composition for forming a polarizing film. As the polymerizable liquid crystal compound and the dichroic dye, the polymerizable liquid crystal compound and the azo dye described in examples of Japanese patent application laid-open No. 2013-101328 are used.

75 parts of a polymerizable liquid crystalline compound represented by the formula (A-6)

[ solution 23]

25 parts of a polymerizable liquid crystalline compound represented by the formula (A-7)

[ solution 24]

2.8 parts of a dichroic dye (1) shown below

[ solution 25]

2.8 parts of a dichroic dye (2) shown below

[ solution 26]

2.8 parts of a dichroic dye (3) shown below

[ solution 27]

Polymerization initiator: 2-dimethylamino-2-benzyl-1- (4-morpholinylphenyl) -1-butanone (Irgacure 369; Ciba Specialty Chemicals) 6 parts

Leveling agent: polyacrylate Compound (BYK-361N; BYK-Chemie Co., Ltd.) 1.2 parts

Compound (B-2): 2 parts of a compound having the following structure (trade name: Laromer (registered trademark) LR-9000, manufactured by BASF Corp.)

[ solution 28]

Solvent: 250 parts of cyclopentanone

(3) Production of acrylic resin film

An acrylic resin film was produced according to the description of Japanese patent laid-open No. 2020 and 56835. An acrylic resin layer-forming composition was obtained by mixing 90 parts of a polyfunctional acrylate monomer (oxiranylated (12) dipentaerythritol hexaacrylate ("NK Ester A-DPH-12E") manufactured by Nippon Mediterranean chemical Co., Ltd.), 10 parts of a urethane acrylate polymer (urethane acrylate ("Violet UV-3310B") manufactured by Nippon synthetic chemical Co., Ltd.), 3 parts of a radical polymerization initiator (phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide ("Irgacure 819") manufactured by BASF Co., Ltd.), and 10 parts of a solvent (methyl ethyl ketone) and stirring the mixture at 50 ℃ for 4 hours.

The release surface of the polyethylene terephthalate film (SP-PLR 382050 manufactured by LINTEC Co., Ltd.) (release film) subjected to the release treatment was subjected to corona treatment, and then the acrylic resin layer-forming composition was applied by a bar coating method (# 230 mm/sec), and the coating layer of the resin layer-forming composition was irradiated with an exposure amount of 500mJ/cm by a UV irradiation apparatus (SPOT CURE SP-7; manufactured by USHIO Motor Co., Ltd.) ² An acrylic resin film having an acrylic resin layer formed on the surface of the release film was obtained by ultraviolet irradiation (365nm basis). The thickness of the acrylic resin layer was 1.5 μm.

(4) Fabrication of polarizing elements

The acrylic resin film produced in the above manner was cut into a square shape (10 cm in length by 10cm in width) as a substrate, and 1 treatment was performed using a corona treatment apparatus (AGF-B10; manufactured by spring Motor Co., Ltd.) at a power output of 0.3kW and a treatment speed of 3 m/min in order to introduce polar groups to the surface of the substrate. The photo-alignment film-forming composition was applied to the corona-treated surface by a bar coater, dried at 80 ℃ for 1 minute, and irradiated at 100mJ/cm using a polarized UV irradiation apparatus (SPOT CURE SP-7 with polarizer unit; manufactured by USHIO Motor Co., Ltd.) ² The cumulative light amount of (2) is subjected to polarized UV exposure to form a photo-alignment film. The thickness of the obtained photo-alignment film was measured by an ellipsometer M-220 (manufactured by Nippon spectral Co., Ltd.), and it was 40 nm.

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 at 120 ℃ for 1 minute.

Thereafter, a high-pressure mercury lamp (manufactured BY UNICURE VB-15201BY-A, USHIO Motor Co., Ltd.) was used to irradiate ultraviolet rays (wavelength: 365nm, cumulative amount of light at wavelength 365nm in nitrogen atmosphere: 1000mJ/cm ² ) Thus, a polarizing film in which the polymerizable liquid crystal compound and the dichroic dye are aligned is formed, and a polarizing element (1) including a substrate, a photo-alignment film, and a polarizing film is obtained. At this time, the thickness of the polarizing film was measured by an ellipsometer, and the result was 2.0 μm.

(5) Evaluation of characteristics

[ evaluation of adhesion ]

The adhesion between the photo-alignment film and the substrate of the obtained polarizing element (1) was evaluated by the following method.

(Cross cut test)

The adhesion between the photo-alignment film and the substrate of the obtained polarizing element (1) was evaluated by the crosscut test (JIS "checkerboard adhesion test") in accordance with JIS D0202-1988. A checkerboard was fabricated by forming scratches penetrating the substrate and the photo-alignment film in a 10X 10 checkerboard pattern at 2mm intervals on the substrate side surface of a 10cm X10 cm polarizer. On the prepared checkerboard surface, an adhesive tape (width 25mm, manufactured by NICIBAN) was completely adhered. The adhesive tape was then pulled in a direction of 90 ° relative to the face.

The number of remaining checkerboards without peeling was measured, and adhesion was evaluated. In addition, it was confirmed by X-ray photoelectron spectroscopy (XPS) that the peeled checkerboard had a peeling interface between the photo-alignment film and the base material. The results are shown in table 1.

[ evaluation of optical Properties (measurement of degree of polarization Py and monomer transmittance Ty) ]

The polarization degree Py and the single transmittance Ty of the polarizing element were measured as follows. In the wavelength range of 380nm to 780nm, the transmittance (Ta) in the transmission axis direction and the transmittance (Tb) in the absorption axis direction were measured by a two-beam method using a device equipped with a holder with a polarizing plate in a spectrophotometer (UV-3150, manufactured by Shimadzu corporation). The reference side of the holder was provided with a mesh that cut off 50% of the light quantity. The monomer transmittance and the degree of polarization at each wavelength were calculated using the following formulae (formula 1) and (formula 2), and the visibility-corrected monomer transmittance (Ty) and the degree of visibility-corrected polarization (Py) were calculated by performing visibility correction using a 2-degree field of view (C light source) according to JIS Z8701. The results are shown in table 1.

Monomer transmittance Ty (%) - (Ta + Tb)/2 (formula 1)

Degree of polarization Py (%) - (Ta-Tb)/(Ta + Tb) × 100 (formula 2)

[ evaluation of bending resistance ]

The coating material described in JIS-K-5600-5-1 was subjected to a method of bending resistance (cylindrical mandrel method) as a general test method, and the bending resistance was evaluated as follows.

The polarizing element (1) was cut into a square of 25 mm. times.200 mm. A mandrel bar having a diameter of 2mm (bending radius R of 1mm) was wound around a cylindrical mandrel bar type II (manufactured by TP techniko corporation) with the polarizing film surface of the cut polarizing element (1) as the outer side at a temperature of 25 ℃ and a relative humidity of 55% RH, and a bending resistance test was performed. The polarizing element (1) after the test was visually checked by transmitted light under illumination in a dark room environment, the occurrence of peeling between the base material and the alignment film was observed, the case where complete peeling was observed was judged to be "x", the case where partial peeling was observed was judged to be "Δ", and the case where no peeling was observed was judged to be "o". The results are shown in table 1.

2. Examples 2 to 23 and comparative example 1

Polarizing elements were produced and evaluated by the same procedure as in example 1, except that the kinds and addition amounts of the alignment polymer (a-1), the compound (a-2) and the compound (B-2) were changed in accordance with the compositions shown in table 1. The obtained results are shown in table 1.

In examples 13 to 18, the following compound (A-2) and compound (B-2) were used.

< Compound (A-2) >)

X-12-1172ES (manufactured by shin-Etsu chemical Co., Ltd.):

[ solution 29]

X-12-1154 (manufactured by shin-Etsu chemical industries, Ltd.): organic chain type, mercapto group-containing

KR-519 (manufactured by shin-Etsu chemical industries, Ltd.): silicone oligomer and mercapto group-containing compound

< Compound (B-2) >)

Karenz A01 (available from Showa Denko K.K.):

[ solution 30]

Karenz BEI (manufactured by Showa Denko K.K.):

[ solution 31]

Karenz MOI-EG (manufactured by Showa Denko K.K.):

[ solution 32]

In Table 1, the amount of the compound (A-2) added represents the amount of the compound (A-2) added per 100 parts by mass of the alignment polymer (A-1), and the amount of the compound (B-2) added represents the amount of the compound (B-2) added per 100 parts by mass of the polymerizable liquid crystal compound.

[ TABLE 1]

Claims

1. A polarizing element comprising a substrate, an alignment film and a polarizing film laminated in this order,

the alignment film is formed by curing an alignment film-forming composition containing an alignment polymer A-1 and a compound A-2 having an active hydrogen-reactive group.

2. The polarizing element of claim 1,

the polarizing film is obtained by curing a composition for polarizing film formation, which contains a polymerizable liquid crystal compound B-1, a compound B-2 having an active hydrogen reactive group, and a dichroic dye B-3.

3. The polarizing element of claim 1 or 2,

compound A-2 also has an active hydrogen-containing group.

4. The polarizing element according to any one of claims 1 to 3,

the alignment polymer a-1 is a polymer having a photoreactive group that causes dimerization reaction.

5. The polarizing element according to any one of claims 1 to 4,

the alignment polymer a-1 is a (meth) acrylic polymer.

6. The polarizing element according to any one of claims 1 to 5,

the weight average molecular weight of oriented polymer A-1 is 10000 to 1000000.

7. The polarizing element according to any one of claims 1 to 6,

the compound A-2 is a silane coupling agent.

8. The polarizing element according to any one of claims 1 to 7,

compound a-2 is a silane coupling agent comprising at least 1 functional group selected from primary amino, secondary amino, hydroxyl, and mercapto.

9. The polarizing element according to any one of claims 1 to 8,

the content of the compound A-2 is 1 to 30 parts by mass relative to 100 parts by mass of the oriented polymer A-1.

10. The polarizing element according to any one of claims 2 to 9,

the compound B-2 further has a polymerizable group.

11. The polarizing element of claim 10,

the polymerizable group is a (meth) acryloyl group.

12. The polarizing element according to any one of claims 2 to 11,

the compound B-2 has 1 or more isocyanate groups and (meth) acryloyl groups, respectively.

13. The polarizing element according to any one of claims 2 to 12,

the content of the compound B-2 is 0.1 to 12 parts by mass per 100 parts by mass of the polymerizable liquid crystal compound B-1.

14. The polarizing element according to any one of claims 2 to 13,

the dichroic dye B-3 comprises a compound represented by the formula (I):

K ¹ (-N＝N-K ² ) _p -N＝N-K ³ (I)

in the formula (I), the compound is shown in the specification,

K ¹ and K ³ Independently of each other, represents an optionally substituted phenyl group, an optionally substituted naphthyl group, an optionally substituted phenylbenzoate group or an optionally substituted 1-valent heterocyclic group,

K ² represents an optionally substituted p-phenylene group, an optionally substituted naphthalene-1, 4-diyl group, an optionally substituted 4, 4' -stilbenylene group or an optionally substituted 2-valent heterocyclic group,

p represents an integer of 0 to 4, and when p is an integer of 2 or more, a plurality of K' s ² Optionally identical or different from each other, optionally in the region of the visible region showing absorption-N ═ N-bonds are replaced by-C ═ C-, -COO-, -NHCO-, -N ═ CH-bonds.

15. The polarizing element according to any one of claims 2 to 14,

the polymerizable liquid crystal compound B-1 is a liquid crystal compound exhibiting smectic liquid crystallinity.

16. The polarizing element according to any one of claims 1 to 15,

the thickness of the base material is 1 μm or more and 10 μm or less.

17. The polarizing element according to any one of claims 1 to 16,

the face of the polarizing film on the side opposite to the orientation film contains an overcoat layer.

18. A method for manufacturing a polarizing element in which a substrate, an alignment film, and a polarizing film are laminated in this order, the method comprising:

(1) a step in which a coating film of an alignment film-forming composition comprising an alignment polymer A-1 and a compound A-2 having an active hydrogen-reactive group is formed on a substrate having a polar group, and the active hydrogen-reactive group of the compound A-2 is reacted with the polar group of the substrate to form a bond by drying the coating film;

(2) forming an alignment film by subjecting the dried coating film obtained in step 1 to rubbing treatment or light irradiation;

(3) forming a coating film of a composition for forming a polarizing film, which comprises a polymerizable liquid crystal compound B-1, a compound B-2 having an active hydrogen-reactive group, and a dichroic dye B-3, on the alignment film obtained in step 2, and drying the coating film; and

(4) and (3) curing the polymerizable liquid crystal compound B-1 and the dichroic dye B-3 in the dried coating film obtained in step 3 in an oriented state to form a polarizing film.

19. The manufacturing method according to claim 18,

further comprises a step of forming an overcoat layer on the polarizing film formed in step 4.

20. A flat panel display device comprising the polarizing element according to any one of claims 1 to 17.

21. A flexible display material comprising the polarizing element of any one of claims 1 to 17.