JP7576408B2 - Polarizing film, polarizing plate, optical laminate, elliptical polarizing plate, organic EL display device, and flexible image display device - Google Patents

Description

The present invention relates to a polarizing film, a polarizing plate including the polarizing film, an optical laminate, an elliptical polarizing plate, an organic EL display device, and a flexible image display device.

Polarizing plates are used in various image display panels such as liquid crystal display panels and organic electroluminescence (organic EL) display panels. Examples of such polarizing plates include polarizing plates having a polarizer in which a dichroic dye such as iodine is oriented and adsorbed on a polyvinyl alcohol resin film, as well as polarizing films having a polarizer obtained by polymerizing a polymerizable liquid crystal compound that is applied to a substrate via a photoalignment film.

JP 2013-33249 A

A polarizing film formed from a coating layer of a liquid crystal compound is often used in the form of a laminate having a polarizer and an alignment film used to form the polarizer. In a polarizing film having such a configuration, a decrease in adhesion between the alignment film and the polarizer can be a factor affecting the optical properties, etc., of the polarizing film.
Therefore, an object of the present invention is to provide a polarizing film having excellent adhesion between a polarizer and an alignment film.

［式（ＩＩ）中、
Ｍａ、ＭｂおよびＭｃは、コポリマーの主鎖を形成するモノマー単位を表し；
ｍ、ｎおよびｌは、コポリマーのモル分率を表すものであって、いずれの場合にも０＜ｍ＜１かつ０＜ｎ＜１かつ０＜ｌ＜１であり；
ＳＰＣＲａ、ＳＰＣＲｂおよびＳＰＣＲｃは、各々独立してスペーサー単位を表し；
環Ａ、環Ｂおよび環Ｃは、各々独立して非置換もしくは置換脂環式炭化水素または非置換もしくは置換芳香環であり；
Ｘは、共有単結合、炭素数１～１０個のアルキレン鎖、または炭素数３～８個のシクロアルキレン鎖であり；
Ｙは、－Ｏ－ＣＯ－ＣＨ＝ＣＨ_２－（いずれの結合手が環Ｂと結合していてもよい）、または－Ｎ＝Ｎ－であり；
Ｚは、共有単結合；非置換、または水酸基および／またはカルボニル基によって置換された炭素数１～１０個のアルキレン鎖；炭素数３～８個のシクロアルキレン鎖；－Ｏ－；－ＣＯＯ－；およびそれらの組み合わせからなる群より選択され；
Ｒ^１は、炭素数１～６個のアルキル基、炭素数１～６個のアルコキシ基、シアノ基およびハロゲン原子から選択される少なくとも１つの置換基を有するフェニル基であり；
Ｒ^２は、－ＣＷ＝ＣＨ_２、または－Ｖ－ＣＷ＝ＣＨ_２（式中、Ｗは水素原子またはメチル基であり、Ｖは－Ｏ－ＣＯ－または－ＣＯ－である）である］
で表される繰り返し単位を有する、［１］～［４］のいずれかに記載の偏光膜。
［６］二色性色素はアゾ色素を含む、［１］～［５］のいずれかに記載の偏光膜。
［７］偏光子は重合性液晶化合物の重合体を含む、［１］～［６］のいずれかに記載の偏光膜。
［８］偏光子はＸ線回折測定においてブラッグピークを示す、［１］～［７］のいずれかに記載の偏光膜。
［９］［１］～［８］のいずれかに記載の偏光膜と、該偏光膜の光配向膜側に配置される基材とを含む偏光板。
［１０］［９］に記載の偏光板と、該偏光板の偏光子側に粘接着層を介して貼合される層とを含む光学積層体。
［１１］［１］～［８］のいずれかに記載の偏光膜と１／４波長板機能を有する位相差層とを含む楕円偏光板。
［１２］［１１］に記載の楕円偏光板を含む、有機ＥＬ表示装置。
［１３］［１１］に記載の楕円偏光板を含む、フレキシブル画像表示装置。
［１４］ウインドウとタッチセンサとをさらに含む、［１３］に記載のフレキシブル画像表示装置。 The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, the present invention provides the following preferred embodiments.
[1] A polarizing film including a photo-aligned film and a polarizer adjacent to the photo-aligned film,
the photoalignment film is formed from a polymer including a structural unit having a photoreactive group and a structural unit having a polymerizable group,
The polarizer is a cured product of a liquid crystal composition containing a liquid crystal compound and a dichroic dye, and the polarizing film contains a structural unit having a polymerizable group derived from the liquid crystal compound or the dichroic dye.
[2] The polarizing film according to [1], wherein the photoreactive group is a group that undergoes a dimerization reaction or an isomerization reaction.
[3] The polarizing film according to [1] or [2], wherein the polymer forming the photo-alignment film further contains a structural unit having a carboxy group.
[4] The polarizing film according to any one of [1] to [3], wherein the polymer forming the photoalignment film has a weight average molecular weight of 20,000 or more and 150,000 or less.
[5] The polymer forming the photoalignment film has the formula (II):

[In the formula (II),
Ma, Mb and Mc represent monomer units forming the backbone of the copolymer;
m, n, and l represent mole fractions of the copolymer, with 0<m<1 and 0<n<1 and 0<l<1 in each case;
SPCRa, SPCRb, and SPCRc each independently represent a spacer unit;
Ring A, ring B and ring C are each independently an unsubstituted or substituted alicyclic hydrocarbon or an unsubstituted or substituted aromatic ring;
X is a single covalent bond, an alkylene chain having 1 to 10 carbon atoms, or a cycloalkylene chain having 3 to 8 carbon atoms;
Y is -O-CO-CH=CH ₂ - (either bond may be bonded to ring B), or -N=N-;
Z is selected from the group consisting of a single covalent bond; an alkylene chain having 1 to 10 carbon atoms which is unsubstituted or substituted with a hydroxyl group and/or a carbonyl group; a cycloalkylene chain having 3 to 8 carbon atoms; -O-; -COO-; and combinations thereof;
R ¹ is a phenyl group having at least one substituent selected from an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group, and a halogen atom;
R ² is -CW=CH ₂ or -V-CW=CH ₂ (wherein W is a hydrogen atom or a methyl group, and V is -O-CO- or -CO-).
The polarizing film according to any one of [1] to [4], which has a repeating unit represented by the following formula:
[6] The polarizing film according to any one of [1] to [5], wherein the dichroic dye comprises an azo dye.
[7] The polarizing film according to any one of [1] to [6], wherein the polarizer contains a polymer of a polymerizable liquid crystal compound.
[8] The polarizing film according to any one of [1] to [7], wherein the polarizer exhibits a Bragg peak in X-ray diffraction measurement.
[9] A polarizing plate comprising the polarizing film according to any one of [1] to [8] and a substrate disposed on the photo-alignment film side of the polarizing film.
[10] An optical laminate comprising the polarizing plate according to [9] and a layer attached to the polarizer side of the polarizing plate via a pressure-sensitive adhesive layer.
[11] An elliptical polarizing plate comprising the polarizing film according to any one of [1] to [8] and a retardation layer having a quarter-wave plate function.
[12] An organic electroluminescence display device comprising the elliptically polarizing plate according to [11].
[13] A flexible image display device comprising the elliptically polarizing plate according to [11].
[14] The flexible image display device according to [13], further comprising a window and a touch sensor.

The present invention provides a polarizing film that has excellent adhesion between the polarizer and the alignment film.

The following describes in detail the embodiments of the present invention. Note that the scope of the present invention is not limited to the embodiments described here, and various modifications can be made without departing from the spirit of the present invention.

[Polarizing film]
The polarizing film of the present invention includes a photo-alignment film and a polarizer adjacent to the photo-alignment film, and is essentially composed of the photo-alignment film and the polarizer. In this specification, a laminate consisting of the photo-alignment film and the polarizer laminated adjacent to the photo-alignment film is referred to as a polarizing film, and when a substrate is disposed on the photo-alignment film side in addition to the photo-alignment film and the polarizer adjacent to the photo-alignment film, a laminate consisting of each layer from the substrate to the polarizer is referred to as a polarizing plate.

The photo-alignment film constituting the polarizing film of the present invention is preferably formed from a polymer containing a structural unit having a photoreactive group and a structural unit having a polymerizable group, and is preferably formed from a copolymer containing a structural unit having a photoreactive group and a structural unit having a polymerizable group. In the present invention, the polymer and the copolymer are usually (co)polymers. In the polymer forming the photo-alignment film, the structural unit having a photoreactive group contributes to imparting liquid crystal alignment ability by the action of light, and the structural unit having a polymerizable group contributes to improving adhesion with the polarizer formed on the photo-alignment film.

In one embodiment of the present invention, the structural unit having a photoreactive group (hereinafter also referred to as "structural unit (i)") is derived from a monomer having at least one photoreactive group. The photoreactive group refers to a group that generates liquid crystal alignment ability upon light irradiation. Specifically, it refers to a group that generates a photoreaction that is the origin of liquid crystal alignment ability upon light irradiation, such as a dimerization reaction, an isomerization reaction, or a photodecomposition reaction, and induces alignment of polymer molecules. The photoreactive group possessed by the structural unit (i) may be one type or two or more types.

A dimerization reaction is a reaction in which an addition reaction occurs between two groups due to the action of light, typically forming a ring structure. Groups that cause such a dimerization reaction include groups containing a carbon-carbon double bond (C=C bond) or a carbon-oxygen double bond (C=O bond) that causes a dimerization reaction when irradiated with light, such as groups having a cinnamoyl structure, groups having a chalcone structure, groups having a coumarin structure, groups having a benzophenone structure, and groups having an anthracene structure. Among these, groups having a cinnamoyl structure and groups having a chalcone structure are preferred, and groups having a cinnamoyl structure are more preferred, from the viewpoint that the amount of polarized light irradiation required for photo-alignment is relatively small and that a photo-alignment film having excellent thermal stability and stability over time can be easily obtained.

An isomerization reaction is a reaction in which a single compound is transformed into other isomers, such as stereoisomerization or structural isomerization, by the action of light. Groups that cause such isomerization reactions include groups that contain a nitrogen-nitrogen double bond (N=N bond) or a carbon-carbon double bond (C=C bond) that induces an isomerization reaction when irradiated with light, such as groups with an azobenzene structure, groups with a stilbene structure, groups with a hydrazono-β-ketoester structure (skeleton), and groups with a spiropyran structure (skeleton).

A photodecomposition reaction is a reaction in which the action of light cuts polymer chains and causes anisotropy.

In the present invention, the photoreactive group is preferably a group that undergoes a dimerization reaction or a group that undergoes an isomerization reaction, and more preferably a group that undergoes a dimerization reaction. Groups that undergo a dimerization reaction and groups that undergo an isomerization reaction are preferred from the standpoint of reactivity and cost. In particular, with regard to reactivity, it is important to react the photoreactive group without reacting the structural unit having a polymerizable group described later.

In one embodiment of the present invention, the structural unit having a polymerizable group (hereinafter also referred to as "structural unit (ii)") is derived from a monomer having at least one polymerizable group. The polymerizable group means a group involved in a polymerization reaction, and examples of such groups include a thermally polymerizable group and a photopolymerizable group. However, it is preferable that the polymerizable group contained in the structural unit having a polymerizable group is a photopolymerizable group. The structural unit (ii) may have one type of polymerizable group or two or more types of polymerizable groups.

Examples of polymerizable groups constituting the structural unit (ii) include vinyl groups, vinyloxy groups, 1-chlorovinyl groups, isopropenyl groups, 4-vinylphenyl groups, (meth)acryloyl groups, (meth)acryloyloxy groups, oxiranyl groups, and oxetanyl groups. Among these, from the viewpoint of ease of reaction control and improved adhesion to the polarizer, preferred are (meth)acryloyl groups, (meth)acryloyloxy groups, vinyloxy groups, oxiranyl groups, and oxetanyl groups, more preferred are (meth)acryloyl groups and (meth)acryloyloxy groups, and even more preferred are (meth)acryloyloxy groups. In this specification, "(meth)acryloyl" refers to methacryloyl and acryloyl.

When the photo-alignment film is formed from a polymer containing a structural unit (ii) having a polymerizable group, a polarizing film having excellent adhesion between the photo-alignment film and the polarizer laminated adjacent thereto can be formed. One of the factors that produces such an effect is that when forming a polarizer, which is a cured product of a liquid crystal composition, the polymerizable group contained in the photo-alignment film reacts with the polymerization reaction of the liquid crystal compound or the liquid crystal substance such as a dichroic dye for forming the polarizer, and can bond with the polymerizable group of the liquid crystal compound or the liquid crystal substance such as a dichroic dye that forms the polarizer. Therefore, when the dichroic dye or polymerizable liquid crystal compound that forms the polarizer has the same polymerizable group as the polymerizable group of the polymer, the adhesion between the polarizer and the photo-alignment film is more likely to be improved.

In the present invention, the polymer forming the photo-alignment film has an unreacted polymerizable group as a structural unit (ii). The structural unit (ii) is derived from a monomer having the polymerizable group. In the polymer, the polymerizable group of at least a part of the monomers forming the polymer remains unreacted. In the structural unit derived from the monomer having the polymerizable group, all of the polymerizable groups may remain unreacted. When a sufficient proportion of unreacted polymerizable groups are present in the polymer, when the polarizer is formed after the formation of the photo-polarizing film, a sufficient amount of polymerizable groups that can react simultaneously with the polymerization reaction of the liquid crystal material to form the polarizer can be present in the photo-alignment film, and therefore the adhesion between the photo-alignment film and the polarizer is likely to be improved.

The polymer that forms the photo-alignment film in the present invention is preferably a polymer having structural units (i) and (ii), since it is easy to form an alignment film that exhibits high liquid crystal alignment ability and has excellent adhesion to a polarizer, and more preferably a polymer in which a photoreactive group and a polymerizable group are located at the ends of the polymer side chains.

Examples of polymers containing structural units (i) and (ii) include polymers obtained by copolymerizing a monomer that derives structural unit (i) with a monomer that derives structural unit (ii), or by introducing a polymerizable group possessed by structural unit (ii) into a (co)polymer containing structural unit (i). Examples of such polymers include copolymers having a structure represented by the following formula (I) as a repeating unit.

［式（Ｉ）中、
ＭｂおよびＭｃは、コポリマーの主鎖を形成するモノマー単位を表し；
ｎおよびｌは、コポリマーのモル分率を表すものであって、いずれの場合にも０＜ｎ＜１かつ０＜ｌ＜１であり；
ＳＰＣＲｂおよびＳＰＣＲｃは、各々独立してスペーサー単位を表し；
環Ｂおよび環Ｃは、各々独立して非置換もしくは置換脂環式炭化水素または非置換もしくは置換芳香環であり；
Ｙは、－Ｏ－ＣＯ－ＣＨ＝ＣＨ_２－（いずれの結合手が環Ｂと結合していてもよい）、または－Ｎ＝Ｎ－であり；
Ｚは、共有単結合；非置換、または水酸基および／またはカルボニル基によって置換された炭素数１～１０個のアルキレン鎖；炭素数３～８個のシクロアルキレン鎖；－Ｏ－；－ＣＯＯ－；およびそれらの組み合わせからなる群より選択され；
Ｒ^１は、炭素数１～６個のアルキル基、炭素数１～６個のアルコキシ基、シアノ基およびハロゲン原子から選択される少なくとも１つの置換基を有するフェニル基であり；
Ｒ^２は、－ＣＷ＝ＣＨ_２、または－Ｖ－ＣＷ＝ＣＨ_２（式中、Ｗは水素原子またはメチル基であり、Ｖは－Ｏ－ＣＯ－または－ＣＯ－である）である。］

[In formula (I),
Mb and Mc represent monomer units forming the backbone of the copolymer;
n and l represent the mole fractions of the copolymer, with 0<n<1 and 0<l<1 in each case;
SPCRb and SPCRc each independently represent a spacer unit;
Ring B and Ring C are each independently an unsubstituted or substituted alicyclic hydrocarbon or an unsubstituted or substituted aromatic ring;
Y is -O-CO-CH=CH ₂ - (either bond may be bonded to ring B), or -N=N-;
Z is selected from the group consisting of a single covalent bond; an alkylene chain having 1 to 10 carbon atoms which is unsubstituted or substituted with a hydroxyl group and/or a carbonyl group; a cycloalkylene chain having 3 to 8 carbon atoms; -O-; -COO-; and combinations thereof;
R ¹ is a phenyl group having at least one substituent selected from an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group, and a halogen atom;
R ² is -CW=CH ₂ or -V-CW=CH ₂ (wherein W is a hydrogen atom or a methyl group, and V is -O-CO- or -CO-).

In formula (I), the structures of Mb and Mc, which are monomer units forming the main chain of the copolymer, include, for example, those selected from the group consisting of (meth)acrylic acid ester units represented by formula (M-1) or formula (M-2); (meth)acrylamide units represented by formula (M-3) or formula (M-4); vinyl ether units represented by formula (M-5) or formula (M-6); (methyl)styrene units represented by formula (M-7) or formula (M-8), and vinyl ester units represented by formula (M-9) or formula (M-10). In formulas (M-1) to (M-10), * represents a bond to the spacer units SPCRb and SPCRc. The main chain of the copolymer in formula (I) is preferably composed of units selected from the above group, and more preferably composed of units selected from the group consisting of (meth)acrylic acid ester units and (meth)acrylamide units. The term "copolymer main chain" used herein refers to the longest molecular chain among the molecular chains contained in the copolymer.

In formula (I), examples of the spacer units SPCRb and SPCRc include a carbonyloxy group (ester bond), an oxygen atom (ether bond), an imide group (imide bond), a carbonylimino group (amide bond), an iminocarbonylimino group (urethane bond), a divalent aliphatic hydrocarbon group which may have a substituent, a divalent aromatic hydrocarbon group which may have a substituent, and a divalent group formed by combining these. Specific examples of the divalent aromatic hydrocarbon group which may have a substituent include a phenylene group, a 2-methoxy-1,4-phenylene group, a 3-methoxy-1,4-phenylene group, a 2-ethoxy-1,4-phenylene group, a 3-ethoxy-1,4-phenylene group, and a 2,3,5-trimethoxy-1,4-phenylene group. Among these, the linking group is preferably an aliphatic hydrocarbon group, and more preferably an alkanediyl group having 1 to 11 carbon atoms which may have a substituent. Examples of such alkanediyl groups include methylene, ethylene, trimethylene, tetramethylene, pentamethylene, hexamethylene, heptamethylene, octamethylene, nonamethylene, decamethylene, and undecamethylene groups, which may be linear or branched. The alkanediyl group may have a substituent. The substituent is, for example, an alkoxy group having 1 to 4 carbon atoms.

In formula (I), examples of ring B and ring C include ring structures represented by formulae (X-1) to (X-5).

In the above structure, X ¹ to X ³⁸ are each independently a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, or a cyano group. The alkyl group represented by X ¹ to X ³⁸ includes an alkyl group having 1 to 4 carbon atoms, and the alkoxy group represented by X ¹ to X ³⁸ includes an alkoxy group having 1 to 4 carbon atoms. Each of X ¹ to X ³⁸ is preferably a hydrogen atom or a halogen atom, and more preferably a hydrogen atom.

Ring B and ring C are preferably ring structures represented by formula (X-1) or (X-5), and more preferably ring structures represented by formula (X-1).

In formula (I), R ¹ is preferably an alkyl group having 1 to 6 carbon atoms, or a phenyl group having at least one substituent selected from a cyano group and a halogen atom, more preferably an alkyl group having 1 to 6 carbon atoms, or a phenyl group substituted with a cyano group, and even more preferably an alkyl group having 1 to 6 carbon atoms. As the alkyl group for ^{R 1} , an alkyl group having 1 to 4 carbon atoms is preferable, and a methyl group is more preferable.

In formula (I), R ² is preferably --CW=CH ₂ or --V-CW=CH ₂ (wherein W is a hydrogen atom or a methyl group, and V is --O--CO-- or --CO--).

In formula (I), n and l are the molar fractions of structural unit (i) and structural unit (ii) relative to the total structural units of the polymer forming the photoalignment film, and preferably satisfy the relationships of 0.1≦n≦0.9 and 0.1≦l≦0.9. It is preferable from the viewpoints of alignment and adhesion that the molar fractions of structural unit (i) and structural unit (ii) are within the above ranges.

Formula (I) is a schematic representation of the presence of a monomer that derives structural unit (i) and a monomer that derives structural unit (ii) in a molar ratio of n:l, and does not necessarily represent that the monomer that derives structural unit (i) and the monomer that derives structural unit (ii) are alternately bonded to form a copolymer. In other words, formula (I) may include any copolymer in which a monomer that derives structural unit (i) and a monomer that derives structural unit (ii) are polymerized in a molar ratio of n:l, such as an alternating type, block type, random type, or graft type.

In one embodiment of the present invention, the polymer that forms the photoalignment film preferably further contains a structural unit having a carboxy group (hereinafter also referred to as "structural unit (iii)") in addition to structural unit (i) and structural unit (ii).

When the photo-alignment film contains the structural unit (iii), the polymer forming the photo-alignment film is preferably a polymer having the structural unit (i), the structural unit (ii) and the structural unit (iii), and more preferably a polymer in which the photoreactive group, the polymerizable group and the carboxy group are each located at the end of the polymer side chain. When the polymer has such a structure, an alignment film having excellent adhesion to the polarizer is easily formed.

Examples of polymers containing structural units (i), (ii), and (iii) include polymers obtained by copolymerizing a monomer that derives structural unit (i), a monomer that derives structural unit (ii), and a monomer that derives structural unit (iii), or by introducing a polymerizable group possessed by structural unit (ii) into a (co)polymer containing structural unit (i) and/or structural unit (iii). Examples of such polymers include copolymers having the structure represented by the following formula (II) as a repeating unit.

［式（ＩＩ）中、
Ｍａ、ＭｂおよびＭｃは、コポリマーの主鎖を形成するモノマー単位を表し；
ｍ、ｎおよびｌは、コポリマーのモル分率を表すものであって、いずれの場合にも０＜ｍ＜１かつ０＜ｎ＜１かつ０＜ｌ＜１であり；
ＳＰＣＲａ、ＳＰＣＲｂおよびＳＰＣＲｃは、各々独立してスペーサー単位を表し；
環Ａ、環Ｂおよび環Ｃは、各々独立して非置換もしくは置換脂環式炭化水素または非置換もしくは置換芳香環であり；
Ｘは、共有単結合、炭素数１～１０個のアルキレン鎖、または炭素数３～８個のシクロアルキレン鎖であり；
Ｙは、－Ｏ－ＣＯ－ＣＨ＝ＣＨ_２－（いずれの結合手が環Ｂと結合していてもよい）、または－Ｎ＝Ｎ－であり；
Ｚは、共有単結合；非置換、または水酸基および／またはカルボニル基によって置換された炭素数１～１０個のアルキレン鎖；炭素数３～８個のシクロアルキレン鎖；－Ｏ－；－ＣＯＯ－；およびそれらの組み合わせからなる群より選択され；
Ｒ^１は、炭素数１～６個のアルキル基、炭素数１～６個のアルコキシ基、シアノ基およびハロゲン原子から選択される少なくとも１つの置換基を有するフェニル基であり；
Ｒ^２は、－ＣＷ＝ＣＨ_２、または－Ｖ－ＣＷ＝ＣＨ_２（式中、Ｗは水素原子またはメチル基であり、Ｖは－Ｏ－ＣＯ－または－ＣＯ－である）である。］

[In the formula (II),
Ma, Mb and Mc represent monomer units forming the backbone of the copolymer;
m, n, and l represent mole fractions of the copolymer, with 0<m<1 and 0<n<1 and 0<l<1 in each case;
SPCRa, SPCRb, and SPCRc each independently represent a spacer unit;
Ring A, ring B and ring C are each independently an unsubstituted or substituted alicyclic hydrocarbon or an unsubstituted or substituted aromatic ring;
X is a single covalent bond, an alkylene chain having 1 to 10 carbon atoms, or a cycloalkylene chain having 3 to 8 carbon atoms;
Y is -O-CO-CH=CH ₂ - (either bond may be bonded to ring B), or -N=N-;
Z is selected from the group consisting of a single covalent bond; an alkylene chain having 1 to 10 carbon atoms which is unsubstituted or substituted with a hydroxyl group and/or a carbonyl group; a cycloalkylene chain having 3 to 8 carbon atoms; -O-; -COO-; and combinations thereof;
R ¹ is a phenyl group having at least one substituent selected from an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group, and a halogen atom;
R ² is -CW=CH ₂ or -V-CW=CH ₂ (wherein W is a hydrogen atom or a methyl group, and V is -O-CO- or -CO-).

In formula (II), the structures of Ma, Mb, and Mc, which are monomer units that form the main chain of the copolymer, include structures similar to those exemplified as the structures of Mb and Mc in formula (I).

In formula (II), the spacer units SPCRa, SPCRb, and SPCRc include structures similar to those exemplified as the structures of SPCRb and SPCRc in formula (I).

In formula (II), ring A, ring B and ring C include the same structures as those exemplified as the structures of ring B and ring C in formula (I).
In formula (II), ring A is preferably a ring structure represented by formula (X-1), and ring B and ring C are preferably ring structures represented by formula (X-1) or (X-5), more preferably ring structures represented by formula (X-1).

Examples of R ¹ and R ² in formula (II) include the same structures as those exemplified as the structures of R ¹ and R ² in formula (II).

In formula (II), m, n, and l are the molar fractions (m+n+l=1) of structural unit (iii), structural unit (i), and structural unit (ii) relative to the total structural units of the polymer forming the photo-alignment film, and preferably satisfy the relationships of 0.1≦m≦0.8, 0.1≦n≦0.5, and 0.1≦l≦0.5, and more preferably satisfy the relationships of 0.3≦m≦0.8, 0.1≦n≦0.3, and 0.1≦l≦0.3. It is preferable from the viewpoint of alignment and adhesion that the molar fractions of structural unit (i), structural unit (ii), and structural unit (iii) are within the above ranges.

Formula (II) is a schematic representation of the presence of a monomer that derives structural unit (i), a monomer that derives structural unit (ii), and a monomer that derives structural unit (iii) in a molar ratio of n:l:m, and does not necessarily represent that the monomer that derives structural unit (i), the monomer that derives structural unit (ii), and the monomer that derives structural unit (iii) are alternately bonded to form a copolymer. In other words, formula (I) may include any of the copolymers obtained by polymerizing the monomer that derives structural unit (i), the monomer that derives structural unit (ii), and the monomer that derives structural unit (iii) in a molar ratio of n:l:m, such as an alternating type, block type, random type, or graft type.

In one embodiment of the present invention, the polymer forming the photoalignment film may contain structural units other than the structural units (i), (ii), and (iii) (hereinafter also referred to as "other structural units") as long as the effect of the present invention is not affected.

The polymer forming the photo-alignment film preferably has a weight-average molecular weight of 20,000 or more and 150,000 or less. When the weight-average molecular weight is equal to or more than the lower limit, the solvent resistance is improved, and the photo-alignment film exhibiting high liquid crystal alignment ability is easily obtained while ensuring high adhesion with the polarizer formed later on the photo-alignment film. In addition, after the photo-alignment film is produced, the alignment tends to be more likely to occur when the liquid crystal composition (polarizer forming composition) is applied. Furthermore, the present inventors have found that within the above range, the larger the weight-average molecular weight of the polymer forming the photo-alignment film, the higher the liquid crystal alignment ability tends to be, and even if the processing temperature when forming the photo-alignment film is relatively high, excellent liquid crystal alignment ability can be exhibited. In the present invention, the weight-average molecular weight of the polymer forming the photo-alignment film is more preferably 30,000 or more, more preferably 50,000 or more, and more preferably 140,000 or less, and more preferably 130,000 or less.
The weight average molecular weight of the polymer can be measured and calculated using a measuring device such as gel permeation chromatography.

The polymer (hereinafter also referred to as "polymer (I')") that forms a photo-alignment film containing structural units (i) and (ii) can be produced by mixing a predetermined amount of a monomer that derives structural unit (i) and a monomer that derives structural unit (ii), and if necessary, a monomer that derives structural unit (iii) and a monomer that derives other structural units in a solventless or solvent-free state and copolymerizing them, or by introducing a polymerizable group possessed by structural unit (ii) during (co)polymerization of a monomer that derives structural unit (i) and/or a monomer that derives structural unit (iii). As a copolymerization method, a method conventionally known in the field may be adopted, and examples of the copolymerization include chain polymerization such as radical polymerization, anionic polymerization, and cationic polymerization, and coordination polymerization. The polymerization conditions are appropriately determined so as to obtain a polymer having a desired molecular weight depending on the type and amount of the monomer used.

When polymerization is performed in a solvent, known organic solvents can be used without any particular limitation. Specific examples of the solvent include alcohol-based solvents such as ethanol, propanol, and butanol; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and cyclopentanone; ester-based solvents such as ethyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate; ether-based solvents such as diethyl ether and diglyme; hydrocarbon-based solvents such as hexane, cyclohexane, methylcyclohexane, toluene, and xylene; nitrile-based solvents such as acetonitrile; and amide-based solvents such as N-methyl-2-pyrrolidone and dimethylacetamide. Any of these solvents may be used alone, or two or more of them may be used in combination.

A polymerization initiator may be used for the polymerization. The polymerization initiator may be appropriately selected from known polymerization initiators, and examples of such initiators include azo-based polymerization initiators such as azobisisobutyronitrile (AIBN), diethyl-2,2'-azobisisobutyrate (V-601), 2,2'-azobis(2,4-dimethylvaleronitrile), and dimethylazobismethylpropionate; peroxide-based polymerization initiators such as benzoyl peroxide, hydrogen peroxide, and lauroyl peroxide; and persulfate-based polymerization initiators such as potassium persulfate and ammonium persulfate. Any of these polymerization initiators may be used alone, or two or more of them may be used in combination.

The polymerization conditions are appropriately determined depending on the type and amount of the monomer used, so as to obtain a polymer having a desired molecular weight.
For example, the temperature during polymerization may be appropriately set depending on the type of monomer, polymerization solvent, polymerization initiator, etc., but is preferably in the range of 40 to 150°C, more preferably 50 to 120°C.

The photo-alignment film is obtained by applying a composition containing a polymer (I') and a solvent that can dissolve the polymer (I') (hereinafter also referred to as the "photo-alignment film forming composition") to a surface of a substrate or the like on which the photo-alignment film is to be formed, drying to remove the solvent, and then irradiating the substrate with polarized light (preferably polarized UV). The photo-alignment film forming composition may contain a polymer material such as polyvinyl alcohol or polyimide, or a photosensitizer, as long as the properties of the photo-alignment film are not significantly impaired.

The content of polymer (I') in the composition for forming a photo-alignment film can be adjusted as appropriate depending on the structure of polymer (I') and the thickness of the desired photo-alignment film, but is preferably at least 0.1% by mass, more preferably 0.3 to 10% by mass, calculated as solid content relative to the mass of the composition for forming a photo-alignment film. In this specification, the solid content refers to the total amount of components excluding volatile components such as solvents from the composition for forming a photo-alignment film. Hereinafter, in the composition for forming a polarizer, etc., it similarly refers to the total amount of components excluding volatile components such as solvents from the target composition.

The solvent used in the photoalignment film forming composition can be appropriately selected depending on the type of polymer (I') used. For example, water; alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, and methyl isobutyl ketone; aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; aromatic hydrocarbon solvents such as toluene and xylene, and nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorine-substituted hydrocarbon solvents such as chloroform and chlorobenzene; and the like. These solvents may be used alone or in combination of two or more.

Methods for applying the photoalignment film-forming composition to a substrate or the like include known methods such as coating methods such as spin coating, extrusion, gravure coating, die coating, bar coating, and applicator methods, and printing methods such as flexography.

Methods for drying and removing the solvent include natural drying, ventilation drying, heat drying, and reduced pressure drying. This results in the formation of a dry coating film.

The method of irradiating polarized light may be a method of irradiating polarized light directly onto a dried coating film obtained by removing the solvent from the composition for forming a photo-aligned film, or a method of irradiating polarized light from the side of the substrate on which the dried coating film is formed and then transmitting the polarized light. It is particularly preferable that the polarized light is substantially parallel light. The wavelength of the polarized light to be irradiated is preferably in a wavelength range in which the photoreactive group in the polymer (I') can absorb light energy. Specifically, UV (ultraviolet light) with a wavelength in the range of 250 to 400 nm is particularly preferable.

Light sources used for the polarized light irradiation include xenon lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, and ultraviolet lasers such as KrF and ArF, with high-pressure mercury lamps, ultra-high-pressure mercury lamps, and metal halide lamps being more preferred. These lamps are preferred because they emit ultraviolet light with a wavelength of 313 nm with high intensity. Polarized light can be irradiated by passing the light from the light source through an appropriate polarizer. Examples of such polarizers include polarizing filters, polarizing prisms such as Glan-Thompson and Glan-Taylor, and wire grid type polarizers.

By masking during polarized light irradiation, it is possible to form multiple regions (patterns) with different liquid crystal alignment directions.

The thickness of the photo-alignment film is preferably 10 to 5000 nm, more preferably 10 to 1000 nm, and even more preferably 30 to 300 nm. When the thickness of the photo-alignment film is in the above range, it can exert an alignment control force while exhibiting good adhesion with the polarizer, and a polarizer can be formed with high alignment order.

The polarizer constituting the polarizing film of the present invention is a cured product of a liquid crystal composition, i.e., a coating layer formed from a liquid crystal composition. The liquid crystal composition that forms the polarizer (hereinafter also referred to as "polarizer-forming composition") contains a liquid crystal compound and a dichroic dye.

The dichroic dye means a dye having different absorbance in the long axis direction of the molecule and absorbance in the short axis direction. The dichroic dye that can be used in the present invention is not particularly limited as long as it has the above-mentioned properties, and may be a dye or a pigment. In addition, two or more types of dyes or pigments may be used in combination, or a dye and a pigment may be used in combination. In addition, the dichroic dye may be polymerizable or liquid crystalline.

In one embodiment of the present invention, the dichroic dye preferably has a maximum absorption wavelength (λ _MAX ) in the range of 300 to 700 nm. Examples of such dichroic dyes include acridine dyes, oxazine dyes, cyanine dyes, naphthalene dyes, azo dyes, and anthraquinone dyes. Among them, azo dyes have high linearity and are therefore suitable for producing a polarizer with excellent polarization performance. Therefore, in one embodiment of the present invention, the dichroic dye contained in the polarizer-forming composition that forms the polarizer is preferably an azo dye.

Examples of the azo dye include monoazo dyes, bisazo dyes, trisazo dyes, tetrakisazo dyes, and stilbene azo dyes. Of these, bisazo dyes and trisazo dyes are preferred, and examples thereof include compounds represented by formula (1).
K ¹ (-N=N-K ² ) _p -N=N-K ³ (1)
[In formula (1), K ¹ and K ³ each independently represent a phenyl group which may have a substituent, a naphthyl group which may have a substituent, or a monovalent heterocyclic group which may have a substituent. K ² represents a p-phenylene group which may have a substituent, a naphthalene-1,4-diyl group which may have a substituent, or a divalent heterocyclic group which may have a substituent. p represents an integer of 1 to 4. When p is an integer of 2 or more, multiple K ^2's may be the same or different from each other. -N=N- bonds may be replaced with -C=C-, -COO-, -NHCO-, or -N=CH- bonds within the range in which absorption is exhibited in the visible range.]

In formula (1), examples of the monovalent heterocyclic group include groups in which one hydrogen atom has been removed from a heterocyclic compound such as quinoline, thiazole, benzothiazole, thienothiazole, imidazole, benzimidazole, oxazole, and benzoxazole. Examples of the divalent heterocyclic group include groups in which two hydrogen atoms have been removed from the above heterocyclic compounds.

In the formula (1), K ¹ and K ³ each represent a phenyl group, a naphthyl group, or a monovalent heterocyclic group, and K In ² , the p-phenylene group, the naphthalene-1,4-diyl group, and the divalent heterocyclic group may optionally have a substituent, such as an alkyl group having 1 to 20 carbon atoms, an alkyl group having 1 to 20 carbon atoms having a polymerizable group, an alkenyl group having 1 to 4 carbon atoms; an alkoxy group having 1 to 20 carbon atoms such as a methoxy group, an ethoxy group, or a butoxy group, an alkoxy group having 1 to 20 carbon atoms having a polymerizable group; a fluorinated alkyl group having 1 to 4 carbon atoms such as a trifluoromethyl group; a cyano group; a nitro group; a halogen atom; an amino group, a diethylamino group, or a substituted or unsubstituted amino group such as a pyrrolidino group (a substituted amino group means an amino group having one or two alkyl groups having 1 to 6 carbon atoms, an amino group having one or two alkyl groups having 1 to 6 carbon atoms having a polymerizable group, or an amino group in which two substituted alkyl groups are bonded to each other to form an alkanediyl group having 2 to 8 carbon atoms. An unsubstituted amino group is _-NH2 .) and the like. Examples of the polymerizable group include an acryloyl group, a methacryloyl group, an acryloyloxy group, and a methacryloyloxy group.

［式（１－１）～（１－８）中、
Ｂ^１～Ｂ^３０は、互いに独立して、水素原子、炭素数１～６のアルキル基、炭素数１～６のアルケニル基、炭素数１～４のアルコキシ基、シアノ基、ニトロ基、置換または無置換のアミノ基（置換アミノ基および無置換アミノ基の定義は前記のとおり）、塩素原子またはトリフルオロメチル基を表わす。
ｎ１～ｎ４は、互いに独立に０～３の整数を表わす。
ｎ１が２以上である場合、複数のＢ^２は互いに同一でも異なっていてもよく、
ｎ２が２以上である場合、複数のＢ^６は互いに同一でも異なっていてもよく、
ｎ３が２以上である場合、複数のＢ^９は互いに同一でも異なっていてもよく、
ｎ４が２以上である場合、複数のＢ^１４は互いに同一でも異なっていてもよい。］ Examples of the azo dye represented by formula (1) include compounds represented by any of the following formulas (1-1) to (1-8). These azo dyes may be used alone or in combination of two or more.

[In formulas (1-1) to (1-8),
B ¹ to B ³⁰ each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, a substituted or unsubstituted amino group (the definitions of a substituted amino group and an unsubstituted amino group are as defined above), a chlorine atom, or a trifluoromethyl group.
n1 to n4 each independently represent an integer of 0 to 3.
When n1 is 2 or more, each ^B2 may be the same or different,
When n2 is 2 or more, multiple ^B6 may be the same or different from each other,
When n3 is 2 or more, multiple ^B9s may be the same or different from each other,
When n4 is 2 or more, multiple B ¹⁴ may be the same or different.

The polarizer constituting the polarizing film of the present invention contains a structural unit having a polymerizable group derived from a liquid crystal compound or a dichroic dye. When the polarizer contains such a structural unit, a bond can be formed between the structural unit (ii) constituting the polymer (I') forming the photo-alignment film and the polymerizable group, making it easier to form a polarizing film with excellent adhesion between the photo-alignment film and the polarizer. Therefore, the dichroic dye in the present invention may be a dichroic dye having a polymerizable group.

When the dichroic dye has a polymerizable group, examples of the polymerizable group include the groups exemplified as the polymerizable group of the structural unit (ii) constituting the polymer (I'). Among them, from the viewpoint of ease of reaction control, a (meth)acryloyl group, a (meth)acryloyloxy group, a vinyloxy group, an oxiranyl group, and an oxetanyl group are preferable, a (meth)acryloyl group and a (meth)acryloyloxy group are more preferable, and a (meth)acryloyloxy group is even more preferable. The polymerizable group in the dichroic dye may be one type alone or a combination of two or more types, but is preferably the same polymerizable group as the polymerizable group of the structural unit (ii). The number of polymerizable groups in the dichroic dye is not particularly limited, and may be one or more.

［式（２）において、
ｍは、０～３の整数を表し；
Ａ^１、Ａ^２およびＡ^３は、互いに独立に、置換基を有していてもよい二価の芳香族基を表し；
Ｌ^１およびＬ^２は、互いに独立に、単結合、－ＣＨ_２－、－ＣＨ_２ＣＨ_２－、－Ｏ－、－ＣＨ_２Ｏ－、－ＯＣＨ_２－、－ＣＯ－、－ＣＯＯ－、－ＯＣＯ－、－ＯＣＯＯ－、－ＣＲ^ｃ＝ＣＲ^ｄ－、－Ｃ≡Ｃ－、－ＣＲ^ｃ＝Ｎ－、－ＣＯＮＲ^ｃ－、－ＮＲ^ｃＣＯ－、または、－Ｎ＝Ｎ－を表し、ここで、Ｒ^ｃおよびＲ^ｄは、互いに独立に、水素原子または炭素数１～４のアルキル基を表す；
Ｚ^１は、重合性基を表し、Ｚ^２は、水素原子または重合性基を表し；
Ｑ^１およびＱ^２は、互いに独立に、置換基を有していてもよい炭素数１～２０の直鎖または分枝アルキレン基、置換基を有していてもよい炭素数１～２０のアルケニレン基、または、置換基を有していてもよい炭素数１～２０のアルキニレン基を表し、これらのアルキレン基、アルケニレン基、または、アルキニレン基に含まれる－ＣＨ_２－は、－Ｏ－、－Ｓ－またはＮＲ^ｅ－で置換されていてもよく、ここで、Ｒ^ｅは水素原子または炭素数１～４のアルキル基を表す；
Ｔ^１は、単結合、－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＯＣＯ－、－ＯＣＯＯ－、または、－ＣＯＮＲ^ｆ－、または、－ＮＲ^ｆＣＯ－を表し、Ｔ^２は、単結合、－Ｏ－、－Ｓ－、－ＣＯ－、－ＣＯＯ－、－ＯＣＯ－、－ＯＣＯＯ－、－ＣＯＮＲ^ｆ－、－ＮＲ^ｆＣＯ－、または、－ＮＲ^ｇ－を表し、ここで、Ｒ^ｆおよびＲ^ｇは、互いに独立に、水素原子または炭素数１～４のアルキル基を表すが、Ｒ^ｇで表されるアルキル基はＱ^１またはＱ^２と環を形成していてもよいが、Ａ^１－（Ｌ^１－Ａ^２）_ｍ－Ｌ^２－Ａ^３は少なくとも一つの－Ａ^Ｘ１－Ｎ＝Ｎ－Ａ^Ｘ２－（式中、Ａ^Ｘ１およびＡ^Ｘ２は、それぞれ２価の芳香族基を表す）を表される構造を含み、Ｔ^２が－ＮＲ^ｇ－である場合にはＺ^２は水素原子を表す］
で表される化合物等が挙げられる。 The dichroic dye having a polymerizable group may be a compound represented by the above formula (1) having a polymerizable group, or a compound represented by the following formula (2):

[In formula (2),
m represents an integer of 0 to 3;
A ¹ , A ² and A ³ each independently represent a divalent aromatic group which may have a substituent;
L ¹ and L ² each independently represent a single bond, -CH ₂ -, -CH ₂ CH ₂ -, -O-, -CH ₂ O-, -OCH ₂ -, -CO-, -COO-, -OCO-, -OCOO-, -CR ^c ═CR ^d -, -C≡C-, -CR ^c ═N-, -CONR ^c -, -NR ^c CO-, or -N═N-, where R ^c and R ^d each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;
Z ¹ represents a polymerizable group, Z ² represents a hydrogen atom or a polymerizable group;
Q ¹ and Q ² each independently represent a linear or branched alkylene group having 1 to 20 carbon atoms which may have a substituent, an alkenylene group having 1 to 20 carbon atoms which may have a substituent, or an alkynylene group having 1 to 20 carbon atoms which may have a substituent, and -CH ₂ - contained in these alkylene groups, alkenylene groups, or alkynylene groups may be substituted with -O-, -S- or NR ^e -, where R ^e represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms;
T ¹ represents a single bond, -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, -CONR ^f -, or -NR ^f CO-; T ² represents a single bond, -O-, -S-, -CO-, -COO-, -OCO-, -OCOO-, -CONR ^f -, -NR ^f CO-, or -NR ^g -; R ^f and R ^g each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and the alkyl group represented by R ^g may form a ring with Q ¹ or Q ² ; and A ¹ -(L ¹ -A ² ) _m -L ² -A ³ represents at least one of -A ^X1 -N═N-A ^X2 - (wherein A ^X1 and A ^X2 each represents a divalent aromatic group, and when ^T2 is -NR ^g -, ^Z2 represents a hydrogen atom.
and the like.

The content of the dichroic dye may be appropriately determined depending on the type of the dichroic dye used. From the viewpoint of easily increasing the adhesion to the photoalignment film and the dichroic ratio, the content may be, for example, 1 to 99 parts by mass, preferably 2 parts by mass or more, more preferably 3 parts by mass or more, relative to 100 parts by mass of the solid content of the composition for forming a polarizing film. In addition, from the viewpoint of easily increasing the degree of orientation order of the polarizer, the content is preferably 80 parts by mass or less, more preferably 50 parts by mass or less, even more preferably 25 parts by mass or less, and particularly preferably 10 parts by mass or less. When a plurality of dichroic dyes are included as the dichroic dye, it is preferable that the total amount of all the dichroic dyes included in the composition for forming a polarizer is within the above range.
The dichroic ratio is the ratio of the absorption intensities of two linearly polarized lights that vibrate perpendicularly to each other when they are incident on a polarizer. It is defined as the ratio (AV/AH) of the absorbance (AV) along the extinction axis (measured at normal incidence) to the absorbance (AH) along the transmission axis. The transmission axis (polarization axis) refers to the polarization direction of the component that transmits through the polarizing film among the light incident on the polarizing film, and the extinction axis (absorption axis) refers to the polarization direction of the component that is absorbed by the polarizing film among the light incident on the polarizing film.

The structural unit having a polymerizable group in the polarizer may be derived from a liquid crystal compound having a polymerizable group. In one embodiment of the present invention, the composition for forming a polarizer preferably contains a polymerizable liquid crystal compound from the viewpoint of easily improving adhesion to the photoalignment film and easily increasing the alignment. Here, the liquid crystal compound refers to a liquid crystal substance exhibiting liquid crystallinity, and the dichroic dye having a polymerizable group described above can also be a type of liquid crystal substance having a polymerizable group, but the polymerizable liquid crystal compound referred to here does not include a dichroic dye having a polymerizable group. Hereinafter, a polymerizable liquid crystal compound other than a dichroic dye having a polymerizable group is referred to as a "polymerizable liquid crystal compound (A)". In the present invention, the composition for forming a polarizer preferably contains a liquid crystal substance having a polymerizable group, and in one embodiment of the present invention, the composition for forming a polarizer contains a polymerizable liquid crystal compound (A) as a liquid crystal substance having a polymerizable group.

Examples of the polymerizable group possessed by the polymerizable liquid crystal compound (A) include the groups exemplified as the polymerizable group possessed by the structural unit (ii) constituting the polymer (I') forming the photo-alignment film. Among them, from the viewpoint of easy control of the reaction, preferred polymerizable groups are (meth)acryloyl group, (meth)acryloyloxy group, vinyloxy group, oxiranyl group and oxetanyl group, more preferably (meth)acryloyl group and (meth)acryloyloxy group, and even more preferably (meth)acryloyloxy group. The polymerizable group in the polymerizable liquid crystal compound (A) may be one type or a combination of two or more types. Since a bond can be formed between the polymerizable group possessed by the structural unit (ii) constituting the polymer (I'), it is easy to form a polarizing film having excellent adhesion between the photo-alignment film and the polarizer, so it is preferable that the polymerizable group possessed by the polymerizable liquid crystal compound (A) is the same polymerizable group as the polymerizable group in the structural unit (ii).

The polymerizable liquid crystal compound (A) may be a thermotropic liquid crystal or a lyotropic liquid crystal, but is preferably a thermotropic liquid crystal. The polymerizable liquid crystal compound (A) may be a thermotropic liquid crystal compound exhibiting a nematic liquid crystal phase or a thermotropic liquid crystal compound exhibiting a smectic liquid crystal phase. In the present invention, the polymerizable liquid crystal compound (A) is preferably a thermotropic liquid crystal compound exhibiting a smectic liquid crystal phase, more preferably a thermotropic liquid crystal compound exhibiting a high-order smectic liquid crystal phase, from the viewpoint of obtaining higher polarization characteristics. Among them, a thermotropic liquid crystal compound exhibiting a smectic B phase, a smectic D phase, a smectic E phase, a smectic F phase, a smectic G phase, a smectic H phase, a smectic I phase, a smectic J phase, a smectic K phase, or a smectic L phase is more preferable, and a thermotropic liquid crystal compound exhibiting a smectic B phase, a smectic F phase, or a smectic I phase is even more preferable. When the liquid crystal phase formed by the polymerizable liquid crystal compound (A) is one of these higher-order smectic phases, it becomes easier to obtain a polarizer with higher polarization performance. In addition, such a polarizer with high polarization performance exhibits Bragg peaks derived from higher-order structures such as hexatic and crystalline phases in X-ray diffraction measurement. The polarizer of the present invention preferably contains a polymer of such a polymerizable liquid crystal compound, preferably a polymer of a polymerizable liquid crystal compound polymerized in a smectic phase state, from the viewpoint of obtaining higher polarization characteristics.

The polymerizable liquid crystal compound (A) is not particularly limited as long as it is a liquid crystal compound having at least one polymerizable group, and a known polymerizable liquid crystal compound can be used, but a compound exhibiting smectic liquid crystallinity is preferable. Examples of such polymerizable liquid crystal compounds include a compound represented by the following formula (A1) (hereinafter, sometimes referred to as "polymerizable liquid crystal compound (A1)").
U ^1A -V ^1A -W ^1A -(X ^1A -Y ^1A -) _n -X ^2A -W ^A2 -V ^2A -U ^2A (A1)
[In formula (A1),
X ^1A and X ^2A each independently represent a divalent aromatic group or a divalent alicyclic hydrocarbon group, wherein a hydrogen atom contained in the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with a halogen atom, an alkyl group having 1 to 4 carbon atoms, a fluoroalkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, or a nitro group, and a carbon atom constituting the divalent aromatic group or the divalent alicyclic hydrocarbon group may be substituted with an oxygen atom, a sulfur atom, or a nitrogen atom, provided that at least one of X ^1A and X ^2A is a 1,4-phenylene group which may have a substituent or a cyclohexane-1,4-diyl group which may have a substituent.
Y ^1A is a single bond or a divalent linking group.
n is 1 to 3, and when n is 2 or more, the multiple ^X1A may be the same as or different from each other. ^X2A may be the same as or different from any or all of the multiple ^X1A . When n is 2 or more, the multiple ^Y1A may be the same as or different from each other. From the viewpoint of liquid crystal properties, n is preferably 2 or more.
U ^1A represents a hydrogen atom or a polymerizable group.
^U2A represents a polymerizable group.
W ^1A and W ^2A are each independently a single bond or a divalent linking group.
V ^1A and V ^2A each independently represent an alkanediyl group having 1 to 20 carbon atoms which may have a substituent, and -CH ₂ - constituting the alkanediyl group may be replaced by -O-, -CO-, -S- or NH-.]

In the polymerizable liquid crystal compound (A1), X ^1A and X ^2A are each independently preferably a 1,4-phenylene group which may have a substituent, or a cyclohexane-1,4-diyl group which may have a substituent, and at least one of X ^1A and X ^2A is a 1,4-phenylene group which may have a substituent, or a cyclohexane-1,4-diyl group which may have a substituent, and is preferably a trans-cyclohexane-1,4-diyl group. Examples of the optional substituent of the 1,4-phenylene group which may have a substituent or the 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, and a butyl group, a cyano group, and a halogen atom such as a chlorine atom or a fluorine atom. It is preferably unsubstituted.

The polymerizable liquid crystal compound (A1) is a compound represented by the formula (A1-1):
-(X ^1A -Y ^1A -) _n -X ^2A - (A1-1)
[In the formula, X ^1A , Y ^1A , X ^2A and n are each as defined above.]
[hereinafter, also referred to as partial structure (A1-1)] preferably has an asymmetric structure in that smectic liquid crystallinity is easily exhibited.
Examples of the polymerizable liquid crystal compound (A1) having an asymmetric structure of the partial structure (A1-1) include a polymerizable liquid crystal compound (A1) in which n is 1 and one X ^1A and one X ^2A have a structure different from each other. Examples of the polymerizable liquid crystal compound (A1) include a compound in which n is 2 and two Y ^1A have the same structure, where the two X ^1A have the same structure and one X ^2A has a structure different from these two X ^1A , and a polymerizable liquid crystal compound (A1) in which the X ^1A bonded to W ^1A of the two X ^1A has a structure different from the other X ^1A and X ^2A , and the other X ^1A and X ^2A have the same structure. Examples of the polymerizable liquid crystal compound (A1) include a compound in which n is 3 and three Y ^1A have the same structure, where one of the three X ^1A and one X ^2A has a structure different from all of the other three.

Y ^1A is preferably -CH ₂ CH ₂ -, -CH ₂ O-, -CH ₂ CH ₂ O-, -COO-, -OCOO-, a single bond, -N=N-, -CR ^a ≡CR ^b -, -C≡C-, -CR ^a ≡N- or -CO-NR ^a -. ^{R a} and R ^b each independently represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Y ^1A is more preferably -CH ₂ CH ₂ -, -COO- or a single bond, and when a plurality of Y ^1A are present, the Y ^1A bonded to X ^2A is more preferably -CH ₂ CH ₂ - or -CH ₂ O-. When X ^1A and X ^2A all have the same structure, it is preferable that there are two or more Y ^1A having different bonding modes. When a plurality of Y ^1A having mutually different bonding modes are present, the structure becomes asymmetric, and therefore smectic liquid crystallinity tends to be easily exhibited.

U ^2A is a polymerizable group. U ^1A is a hydrogen atom or a polymerizable group, preferably a polymerizable group. It is preferable that both U ^1A and U ^2A are polymerizable groups, and it is preferable that both are radically polymerizable groups. Examples of the polymerizable group include the same groups as those exemplified above as the polymerizable group possessed by the polymerizable liquid crystal compound (A). If the polymerizable group is the same polymerizable group as the polymerizable group in the structural unit (ii) constituting the polymer (I') forming the photo-alignment film, the adhesion between the photo-alignment film and the polarizer tends to be improved, which is preferable. The polymerizable group represented by U ^1A and the polymerizable group represented by U ^2A may be different from each other, but are preferably the same type of group. Furthermore, it is preferable that at least one of U ^1A and U ^2A is a (meth)acryloyl group, and it is more preferable that both are (meth)acryloyl groups. In addition, the polymerizable group may be in a polymerized state or an unpolymerized state, but is preferably in an unpolymerized state.

Examples of the alkanediyl group represented by V ^1A and V ^2A include a methylene group, an ethylene group, a propane-1,3-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diyl group, a heptane-1,7-diyl group, an octane-1,8-diyl group, a decane-1,10-diyl group, a tetradecane-1,14-diyl group, and an icosane-1,20-diyl group, etc. V ^1A and V ^2A are preferably alkanediyl groups having 2 to 12 carbon atoms, more preferably alkanediyl groups having 6 to 12 carbon atoms.

Substituents that the alkanediyl group may optionally have include a cyano group and a halogen atom, but the alkanediyl group is preferably unsubstituted, and more preferably an unsubstituted linear alkanediyl group.

W ^1A and W ^2A each independently preferably represent a single bond, —O—, —S—, —COO— or —OCOO—, more preferably a single bond or —O—.

The polymerizable liquid crystal compound (A) is not particularly limited as long as it has at least one polymerizable group and exhibits liquid crystallinity, and known polymerizable liquid crystal compounds can be used. As the polymerizable liquid crystal compound (A), a polymerizable liquid crystal compound exhibiting smectic liquid crystallinity is preferable, and a compound exhibiting high-order smectic liquid crystallinity is more preferable. As a structure that is likely to exhibit smectic liquid crystallinity, it is preferable to have an asymmetric molecular structure in the molecular structure, and specifically, it is more preferable to have a polymerizable liquid crystal compound having a structure represented by the following formulas (A-a) to (A-i) and exhibiting smectic liquid crystallinity. From the viewpoint of being likely to exhibit high-order smectic liquid crystallinity, it is more preferable to have a structure represented by any of formulas (A-a), (A-b), and (A-c), and it is particularly preferable to have a structure represented by formula (A-a) or formula (A-c). In the following formulas, * represents a bond.

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

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

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

In the present invention, when the polarizer-forming composition contains the polymerizable liquid crystal compound (A), the content thereof may be, for example, 1 to 99 parts by mass relative to 100 parts by mass of the solid content of the polarizer-forming composition, and is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, even more preferably 60 parts by mass or more, particularly preferably 70 parts by mass or more, and especially preferably 80 parts by mass or more, and is preferably 98 parts by mass or less, more preferably 95 parts by mass or less.

When the polarizer-forming composition contains two or more polymerizable liquid crystal compounds (A), at least one of them may be a polymerizable liquid crystal compound (A1), or all of them may be polymerizable liquid crystal compounds (A1). By combining multiple polymerizable liquid crystal compounds, it may be possible to temporarily maintain liquid crystallinity even at temperatures below the liquid crystal-crystal phase transition temperature.

The polarizer-forming composition may further include a polymerization initiator. The polymerization initiator is a compound capable of initiating a polymerization reaction of a liquid crystal material having a polymerizable group that may be included in the polarizer-forming composition. The polymerization initiator is not particularly limited as long as it is a compound capable of initiating a polymerization reaction of a liquid crystal material having a polymerizable group, and a known polymerization initiator, preferably a photopolymerization initiator, may be used. Specifically, a photopolymerization initiator that generates active radicals upon irradiation with light, or a photopolymerization initiator that generates an acid may be used. The photopolymerization initiator may be used alone or in combination of two or more kinds.

Examples of photopolymerization initiators that generate active radicals include self-cleavage type photopolymerization initiators such as benzoin compounds, acetophenone compounds, hydroxyacetophenone compounds, α-aminoacetophenone compounds, oxime ester compounds, acylphosphine oxide compounds, and azo compounds, and hydrogen abstraction type photopolymerization initiators such as benzophenone compounds, alkylphenone compounds, benzoin ether compounds, benzyl ketal compounds, dibenzosuberone compounds, anthraquinone compounds, xanthone compounds, thioxanthone compounds, halogenoacetophenone compounds, dialkoxyacetophenone compounds, halogenobisimidazole compounds, halogenotriazine compounds, and triazine compounds.
Examples of photopolymerization initiators that generate an acid include iodonium salts and sulfonium salts.
Among these photopolymerization initiators, photopolymerization initiators which generate active radicals upon irradiation with light are preferred, and among these, from the viewpoint of excellent reaction efficiency at low temperatures, self-cleavage type photopolymerization initiators are preferred, and in particular, acetophenone-based compounds, hydroxyacetophenone-based compounds, α-aminoacetophenone-based compounds, and oxime ester-based compounds are preferred.

Examples of benzoin compounds include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether.

Examples of acetophenone compounds include diethoxyacetophenone, 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexyl phenyl ketone, and oligomers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one.

Examples of oxime ester compounds include Irgacure (registered trademark) OXE-01, Irgacure (registered trademark) OXE-02, Irgacure (registered trademark) OXE-03 (all manufactured by BASF Japan Ltd.), ADEKA Optomer (registered trademark) N-1919, ADEKA Arcles (registered trademark) NCI-831 (all manufactured by ADEKA Corporation).

Examples of acylphosphine oxide compounds include 2,4,6-trimethylbenzoyldiphenylphosphine oxide and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide.

Examples of benzophenone compounds include benzophenone, o-benzoylmethylbenzoate, 4-phenylbenzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(tert-butylperoxycarbonyl)benzophenone, and 2,4,6-trimethylbenzophenone.

Examples of alkylphenone compounds include diethoxyacetophenone, 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1,2-diphenyl-2,2-dimethoxyethane-1-one, 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one, 1-hydroxycyclohexyl phenyl ketone, and oligomers of 2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propan-1-one.

Examples of triazine compounds include 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, and 2,4-bis(trichloromethyl)-6-[2-(5-methylfuran-2-yl)ethenyl] yl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(furan-2-yl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(4-diethylamino-2-methylphenyl)ethenyl]-1,3,5-triazine, 2,4-bis(trichloromethyl)-6-[2-(3,4-dimethoxyphenyl)ethenyl]-1,3,5-triazine, etc.

Polymerization initiators include Irgacure 907, Irgacure 184, Irgacure 651, Irgacure 819, Irgacure 250, Irgacure 369 (all manufactured by Chiba Japan Co., Ltd.), Seikuol BZ, Seikuol Z, Seikuol BEE (all manufactured by Seiko Chemical Co., Ltd.), Kayacure BP100 (manufactured by Nippon Kayaku Co., Ltd.), Kayacure UVI-6992 (manufactured by Dow), Adeka Optomer SP-152 or Adeka Optomer SP-170 (all manufactured by ADEKA Co., Ltd.), TAZ-A, TAZ-PP (manufactured by Nippon SiberHegner Co., Ltd.), TAZ-104 (manufactured by Sanwa Chemical Co., Ltd.), Esacure One, Esacure Commercially available photopolymerization initiators such as KIP 150 (all manufactured by IGM Resins) can also be used.

When the polarizer-forming composition contains a polymerization initiator, the content of the polymerization initiator may be appropriately adjusted according to the type and amount of the liquid crystal substance having a polymerizable group contained in the polarizer-forming composition that is involved in the polymerization reaction. The content of the polymerization initiator is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, per 100 parts by mass of the solid content of the polarizer-forming composition.

The polarizer-forming composition may contain additives as necessary, as long as they do not impair the effects of the present invention. Examples of additives include sensitizers, polymerization inhibitors, and leveling agents.

The polarizer-forming composition may contain a sensitizer. The sensitizer is preferably a photosensitizer. Examples of the sensitizer include xanthone compounds such as xanthone or thioxanthone (e.g., 2,4-diethylthioxanthone, 2-isopropylthioxanthone, etc.), anthracene or anthracene compounds having a substituent such as an alkyl ether (e.g., dibutoxyanthracene, etc.), phenothiazine, or rubrene.

When the polarizer-forming composition contains a sensitizer, the polymerization reaction of the liquid crystal substance having a polymerizable group contained in the composition is promoted, and the film strength of the resulting polarizer is likely to be improved. When the polarizer-forming composition contains a photosensitizer, the content of the sensitizer is preferably 0.1 to 30 parts by mass, more preferably 0.3 to 10 parts by mass, and even more preferably 0.5 to 8.0 parts by mass, relative to 100 parts by mass of the solid content of the polarizer-forming composition, from the viewpoint of easily promoting the polymerization reaction without impairing the alignment of the resulting polarizer.

Examples of polymerization inhibitors include hydroquinone or hydroquinones with a substituent such as alkyl ether, catechols with a substituent such as alkyl ether, such as butylcatechol, pyrogallols, radical scavengers such as 2,2,6,6-tetramethyl-1-piperidinyloxy radical, thiophenols, β-naphthylamines, and β-naphthols.

When the polarizer-forming composition contains a polymerization inhibitor, the composition can be polymerized while suppressing the occurrence of alignment disorder of the liquid crystal material having a polymerizable group. When the polarizer-forming composition contains a polymerization inhibitor, the content of the polymerization inhibitor is preferably 0.1 to 30 parts by mass, more preferably 0.3 to 10 parts by mass, and even more preferably 0.5 to 8.0 parts by mass, relative to 100 parts by mass of the solid content of the polarizer-forming composition, from the viewpoint of the effect of suppressing alignment disorder of the liquid crystal material having a polymerizable group.

The polarizer-forming composition may contain a leveling agent. The leveling agent is an additive that adjusts the fluidity of the composition and makes the film obtained by applying the composition flatter. Examples of the leveling agent include organic modified silicone oil-based, polyacrylate-based, and perfluoroalkyl-based leveling agents. Specifically, DC3PA, SH7PA, DC11PA, SH28PA, SH29PA, SH30PA, ST80PA, ST86PA, SH8400, SH8700, FZ2123 (all manufactured by Dow Corning Toray Co., Ltd.), KP321, KP323, KP324, KP326, KP340, KP341, X22-161A, KF6001 (all manufactured by Shin-Etsu Chemical Co., Ltd.), TSF400, TSF401, TSF410, TSF4300, TSF4440, TSF4445, TSF-4446, TSF4452, TSF4460 (all manufactured by Momentive Performance Materials, Inc.) Japan LLC), Fluorinert (registered trademark) FC-72, FC-40, FC-43, FC-3283 (all manufactured by Sumitomo 3M Limited), Megafac (registered trademark) R-08, R-30, R-90, F-410, F-411, F-443, F-445, F-470, F-477, F-479, F-482, F-483 (all manufactured by DIC Corporation), F-top (trade name) EF301, EF303, EF351, EF352 (all manufactured by Mitsubishi Materials Electronics Co., Ltd.), Surflon (registered trademark) S-381, S-382, S-383, S-393, SC-101, SC-105, KH-40, SA-100 (all manufactured by AGC Seimi Chemical Co., Ltd.), trade names E1830, E5844 (manufactured by Daikin Fine Chemical Research Institute Co., Ltd.), BM-1000, BM-1100, BYK-352, BYK-353 and BYK-361N (all trade names manufactured by BM Chemie Co., Ltd.), etc. Among them, polyacrylate-based leveling agents and perfluoroalkyl-based leveling agents are preferred.

When the polarizer-forming composition contains a leveling agent, the amount of the leveling agent is preferably 0.01 to 30 parts by mass, more preferably 0.03 to 10 parts by mass, and even more preferably 0.05 to 8.0 parts by mass, per 100 parts by mass of the solid content of the polarizer-forming composition, from the viewpoints of improving the alignment and making it easier to smooth the resulting polarizer. The leveling agents may be used alone or in combination of two or more kinds.

Additives other than the sensitizer, polymerization inhibitor, and leveling agent that may be contained in the polarizer-forming composition include, for example, antioxidants, release agents, stabilizers, colorants such as bluing agents, flame retardants, and lubricants. When the polarizer-forming composition contains these additives, the total mass of the additive content is preferably more than 0% and not more than 20% by mass, more preferably more than 0% and not more than 10% by mass, based on the solid content of the polarizer-forming composition.

The polarizer-forming composition can be produced by a conventionally known preparation method, and can usually be prepared by mixing and stirring a dichroic dye, a polymerizable liquid crystal compound (A) if necessary, a polymerization initiator, and the above-mentioned additives. In addition, since compounds that exhibit smectic liquid crystal properties generally have high viscosity, the viscosity may be adjusted by adding a solvent to the polarizer-forming composition in order to improve the coatability of the polarizer-forming composition and facilitate the formation of a polarizer.

As a solvent, an organic solvent that can dissolve the components contained in the polarizer-forming composition and is inactive in the polymerization reaction is preferred. Specific examples of the organic solvent include alcohol solvents such as methanol, ethanol, ethylene glycol, isopropyl alcohol, propylene glycol, methyl cellosolve, butyl cellosolve, and propylene glycol monomethyl ether; ester solvents such as ethyl acetate, butyl acetate, ethylene glycol methyl ether acetate, γ-butyrolactone, propylene glycol methyl ether acetate, and ethyl lactate; ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl amyl ketone, and methyl isobutyl ketone; non-chlorinated aliphatic hydrocarbon solvents such as pentane, hexane, and heptane; non-chlorinated aromatic solvents such as toluene, xylene, and phenol, and nitrile solvents such as acetonitrile; ether solvents such as tetrahydrofuran and dimethoxyethane; chlorinated aliphatic hydrocarbon solvents such as chloroform and chlorobenzene; and amide solvents such as dimethylacetamide, dimethylformamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone. These organic solvents may be used alone or in combination of two or more.

When the polarizer-forming composition contains a solvent, the solids concentration of the polarizer-forming composition is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, and is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. If the solids concentration is equal to or higher than the lower limit, the resulting polarizer does not become too thin, and the dichroism required for the polarizer is easily obtained. If the solids concentration is equal to or lower than the upper limit, the viscosity of the polarizer-forming composition is low, and the coating thickness of the composition tends to be less uneven.

The viscosity of the polarizer-forming composition is preferably 0.1 to 10 mPa·s, more preferably 0.1 to 7 mPa·s, and even more preferably 0.1 to 5 mPa·s. When the viscosity of the polarizer-forming composition is within the above range, the composition has excellent handleability and coatability, and the thickness of the resulting polarizer is easily made uniform.

In the present invention, the polarizer is a cured product of a liquid crystal composition (composition for forming a polarizer), and can be obtained by polymerizing the liquid crystal substance contained in the composition. A polarizer is a device that decomposes unpolarized incident light into two orthogonal polarized components, transmits one polarized component, and absorbs the other polarized component. The axial direction of the transmitted polarized component is called the transmission axis, and the axial direction of the absorbed polarized component is called the absorption axis.

In the present invention, the polarizer is adjacent to the photo-alignment film, and can exhibit high adhesion to the photo-alignment film. One of the factors that produces this effect is that when forming a polarizer, which is a cured product of a liquid crystal composition, the liquid crystal compound or dichroic dye having a polymerizable group for forming the polarizer undergoes a polymerization reaction, and the polymerizable group contained in the polymer (I') that constitutes the photo-alignment film reacts and bonds with the polymerizable group of the liquid crystal compound or dichroic dye that forms the polarizer, resulting in a tighter bond between the polarizer and the photo-alignment film.

In addition, the photo-alignment film formed from the polymer (I') has excellent solvent resistance, and therefore exhibits high liquid crystal alignment ability, making it easy to form a polarizer with a high degree of alignment order. A polarizer with a high degree of alignment order exhibits a Bragg peak derived from a higher-order structure such as a hexatic phase or a crystalline phase in X-ray diffraction measurement. The Bragg peak means a peak derived from the planar periodic structure of molecular alignment, and it is preferable that the polarizer constituting the polarizing film of the present invention exhibits a Bragg peak in X-ray diffraction measurement. That is, in the polarizer constituting the polarizing film of the present invention, it is preferable that the polymerizable liquid crystal compound or its polymer is oriented so that the polarizer exhibits a Bragg peak in X-ray diffraction measurement, and it is more preferable that the molecules of the polymerizable liquid crystal compound are "horizontally oriented" in the direction in which light is absorbed. In the present invention, a polarizer with a planar periodicity interval of the molecular alignment of 3.0 to 6.0 Å is preferable. A high degree of alignment order that exhibits a Bragg peak can be achieved by controlling the type of polymerizable liquid crystal compound used, the type and amount of the dichroic dye, and the type and amount of the polymerization initiator.

The thickness of the polarizer can be appropriately determined depending on the application of the optical laminate in which the polarizing film is incorporated, but is preferably 0.1 μm to 10 μm, more preferably 0.3 μm to 5 μm, and even more preferably 0.5 μm to 3 μm. If the thickness of the polarizer is equal to or greater than the lower limit, the liquid crystal material is less likely to be oriented in the vertical direction, and the orientation order is more likely to be improved. If the thickness of the polarizer is equal to or less than the upper limit, the liquid crystal material is less likely to be oriented randomly, and the orientation order is more likely to be improved. The thickness of the polarizer can be measured using an interference film thickness gauge, a laser microscope, a stylus film thickness gauge, or the like.

The polarizer can be obtained, for example, by a method including applying a polarizer-forming composition onto a photo-alignment film and curing the applied polarizer-forming composition.
In one embodiment of the present invention, when the polarizer-forming composition contains a solvent, a polarizer may be formed by applying the polarizer-forming composition, removing the solvent contained in the composition, and curing the polarizer-forming composition from which the solvent has been removed.
Furthermore, when the composition for forming a polarizer contains a polymerizable liquid crystal compound as a liquid crystalline substance, the polarizer can be obtained, for example, by a method including raising the temperature to a temperature at which the polymerizable liquid crystal compound undergoes a phase transition to a liquid phase or higher, and then lowering the temperature to cause the polymerizable liquid crystal compound to undergo a phase transition to a liquid crystal phase (smectic phase), and polymerizing the polymerizable liquid crystal compound while maintaining the liquid crystal phase.

Methods for applying the polarizer-forming composition onto the photoalignment film include known methods such as spin coating, extrusion, gravure coating, die coating, bar coating, and applicator coating, and printing methods such as flexography.

When removing the solvent, the solvent is removed by drying or the like, preferably under conditions in which the polymerizable liquid crystal compound contained in the coating film of the polarizer-forming composition does not polymerize, to form a dry coating film. Drying methods include natural drying, forced air drying, heat drying, and reduced pressure drying.

The drying temperature may be, for example, 50 to 200°C, and is preferably 100°C or higher, more preferably 110°C or higher, even more preferably 120°C or higher, and is preferably 150°C or lower. When the drying temperature is within the above range, the solvent in the coating film can be efficiently removed. In addition, the effect of temperature on the photo-alignment film on which the coating film is formed can be suppressed, making it difficult for the liquid crystal alignment ability of the photo-alignment film to decrease. The drying time is preferably 20 seconds to 10 minutes, and more preferably 30 seconds to 5 minutes.

When the liquid crystalline substance is caused to undergo a phase transition to a liquid phase, such phase transition may be carried out after the solvent in the coating film is removed, or may be carried out simultaneously with the removal of the solvent.

By polymerizing the liquid crystal substance while maintaining the liquid crystal state, a polarizer is formed as a cured product of the polarizer-forming composition. The polymerization method may be appropriately selected from photopolymerization, thermal polymerization, etc., depending on the type of polymerizable group. When polymerization is performed by photopolymerization, polymerization at low temperatures is possible and industrial production is easy, so in one embodiment of the present invention, photopolymerization is preferred as the polymerization method. In photopolymerization, the light irradiated to the dried coating film is appropriately selected depending on the type of polymerizable liquid crystal compound, etc. contained in the dried coating film (particularly, the type of polymerizable group possessed by the polymerizable liquid crystal compound, etc.), the type of polymerization initiator, and the amount thereof. Specific examples include one or more active energy rays and active electron rays selected from the group consisting of visible light, ultraviolet light, infrared light, X-rays, α rays, β rays, and γ rays. Among them, ultraviolet light is preferred because it is easy to control the progress of the polymerization reaction and because photopolymerization devices widely used in this field can be used. It is preferable to select the type of polymerizable liquid crystal compound and polymerization initiator contained in the polarizer-forming composition so that they can be photopolymerized by ultraviolet light. In addition, the polymerization temperature can be controlled by irradiating light while cooling the dried coating film with an appropriate cooling means. During photopolymerization, a patterned polarizer can also be obtained by performing masking and development.

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

The ultraviolet irradiation intensity is usually 10 to 3,000 mW/ ^cm2 . The ultraviolet irradiation intensity is preferably an intensity in a wavelength region effective for activating a polymerization initiator. The time for irradiating light is usually 0.1 seconds to 10 minutes, preferably 1 second to 5 minutes, more preferably 5 seconds to 3 minutes, and even more preferably 10 seconds to 1 minute. When irradiating once or multiple times with such ultraviolet irradiation intensity, the integrated light amount is 10 to 3,000 mJ/ ^cm2 , preferably 50 to 2,000 mJ/ ^cm2 , and more preferably 100 to 1,000 mJ/ ^cm2 .

When the composition for forming a polarizer contains a polymerizable liquid crystal compound (A), the polymerizable liquid crystal compound (A) is polymerized by photopolymerization while maintaining the liquid crystal state of the liquid crystal phase, particularly the smectic phase, and preferably the high-order smectic phase, to form a polarizer. The polarizer obtained by polymerizing the polymerizable liquid crystal compound while maintaining the liquid crystal state of the smectic phase has the advantage of having higher polarization performance due to the action of the dichroic dye compared to conventional host-guest type polarizing films, i.e., polarizers consisting of a liquid crystal state of a nematic phase. Furthermore, it has the advantage of having superior strength compared to those coated with only a dichroic dye or lyotropic liquid crystal.

[Polarizing Plate]
The present invention also includes a polarizing plate comprising the polarizing film of the present invention and a substrate disposed on the photoalignment film side of the polarizing film.

Examples of the substrate include glass substrates and film substrates, with film substrates being preferred. Examples of the resin constituting the film substrate include polyolefins such as polyethylene, polypropylene, and norbornene-based polymers; cyclic olefin-based resins; polyvinyl alcohol; polyethylene terephthalate; polymethacrylic acid esters; polyacrylic acid esters; cellulose esters such as triacetyl cellulose, diacetyl cellulose, and cellulose acetate propionate; polyethylene naphthalate; polycarbonate; polysulfone; polyether sulfone; polyether ketone; polyphenylene sulfide, and polyphenylene oxide.

Examples of commercially available cellulose ester substrates include "FUJITAC FILM" (manufactured by Fuji Photo Film Co., Ltd.); "KC8UX2M", "KC8UY" and "KC4UY" (all manufactured by Konica Minolta Opto, Inc.).
Examples of commercially available cyclic olefin resins include "Topas" (registered trademark) (manufactured by Ticona (Germany)), "Arton" (registered trademark) (manufactured by JSR Corporation), "ZEONOR" (registered trademark), "ZEONEX" (registered trademark) (all manufactured by Zeon Corporation), and "Apel" (registered trademark) (manufactured by Mitsui Chemicals, Inc.). Such cyclic olefin resins can be formed into a film by known means such as a solvent casting method or a melt extrusion method to form a substrate. Commercially available cyclic olefin resin substrates can also be used. Examples of commercially available cyclic olefin resin substrates include "S-Cina" (registered trademark), "SCA40" (registered trademark) (all manufactured by Sekisui Chemical Co., Ltd.), "ZEONOR Film" (registered trademark) (manufactured by Optes Co., Ltd.), and "Arton Film" (registered trademark) (manufactured by JSR Corporation).

The properties required of the substrate vary depending on the configuration of the polarizing plate, but generally, a substrate with as little retardation as possible is preferred. Examples of substrates with as little retardation as possible include cellulose ester films with no retardation, such as Zerotac (Konica Minolta Opto, Inc.) and Ztac (Fujifilm Corporation). Unstretched cyclic olefin resin substrates are also preferred. The surface of the substrate on which the polarizing film is not laminated may be subjected to a hard coat treatment, anti-reflection treatment, anti-static treatment, etc.

The thickness of the substrate is preferably thin from the viewpoint of practical handling, but is preferably thick from the viewpoint of strength and processability. In one embodiment of the present invention, the thickness of the substrate is preferably 5 μm to 300 μm, and more preferably 20 μm to 200 μm. In addition, since it is possible to apply only the polarizing film of the present invention to an optical laminate such as an elliptical polarizing plate by peeling the polarizing film from the substrate and transferring the polarizing film, the effect of further reducing the thickness of the optical laminate used in an image display panel, etc. can be obtained.

[Optical laminate]
The present invention also includes an optical laminate including the polarizing plate of the present invention and a layer attached to the polarizer side of the polarizing plate via a tacky adhesive layer. In such an optical laminate, examples of the layer attached to the polarizer of the present invention include various optical layers, protective layers, and the like. Examples of the various optical layers include layers that function for image display (display screen, etc.) (for example, layers that function to improve the visibility of images) and films having various optical properties that can be incorporated into image display devices. Such optical layers may be, for example, a single-layer structure (for example, optically functional films such as retardation films, brightness-enhancing films, anti-glare films, anti-reflection films, diffusion films, and light-collecting films) or a multilayer structure (for example, retardation plates, etc.).

In the optical laminate of the present invention, the adhesive layer for adhesively bonding the polarizer and the layer to be attached to the polarizer is a layer formed from an adhesive. As the adhesive forming the adhesive layer, any adhesive conventionally known in the art can be used depending on the type of layer to be attached to the polarizer, the layer configuration of the optical laminate, and the like.
The thickness of the adhesive layer may be appropriately determined depending on the layer structure of the optical laminate, and may be, for example, 0.1 to 30 μm.

The present invention also includes an elliptical polarizing plate comprising the polarizing film of the present invention and a retardation layer having a quarter-wave plate function (hereinafter also referred to as a "λ/4 retardation layer"). The (elliptical) circular polarizing plate is a functional layer having a function of transmitting only right- or left-handed circularly polarized light components by laminating a λ/4 retardation plate on a linear polarizing plate. The elliptical polarizing plate of the present invention may have a λ/4 retardation layer on either side of the polarizing film of the present invention.

The λ/4 retardation layer constituting the elliptically polarizing plate of the present invention preferably satisfies the optical properties represented by the following formulas (a), (b) and (c).
Re(450)/Re(550)≦1.00 (a)
1.00≦Re(650)/Re(550) (b)
120≦Re(550)≦180 (c)
[In the formula, Re(λ) represents an in-plane retardation value of the retardation layer at a wavelength of λ nm, and Re=(nx(λ)-ny(λ))×d (d represents a thickness of the retardation layer, nx represents a principal refractive index at a wavelength of λ nm in a direction parallel to the plane of the retardation layer in an index ellipsoid formed by the retardation layer, and ny represents a refractive index at a wavelength of λ nm in a direction parallel to the plane of the retardation layer and perpendicular to the direction of nx in an index ellipsoid formed by the retardation layer).]

When the retardation layer satisfies the formulas (a) and (b), the retardation layer exhibits so-called reverse wavelength dispersion, in which the in-plane retardation value at a short wavelength is smaller than the in-plane retardation value at a long wavelength. Since the reverse wavelength dispersion is improved and the optical characteristics are more likely to be improved when the retardation layer is incorporated into an image display device or the like, Re(450)/Re(550) is preferably 0.70 or more, more preferably 0.78 or more, and preferably 0.92 or less, more preferably 0.90 or less, even more preferably 0.87 or less, particularly preferably 0.86 or less, and even more particularly preferably 0.85 or less. In addition, Re(650)/Re(550) is preferably 1.0 or more, more preferably 1.01 or more, and even more preferably 1.02 or more.

The retardation layer may be a stretched film that imparts retardation by stretching a polymer, or a liquid crystal cured layer made of a cured liquid crystal composition that contains a polymerizable liquid crystal compound. These λ/4 retardation layers can be manufactured by appropriately selecting and employing materials and methods that are conventionally known in the field.

The thickness of the λ/4 retardation layer is not particularly limited and may be, for example, 100 μm or less. From the viewpoint of thinning the image display device in which it is incorporated, the thickness is preferably 0.5 μm to 20 μm, and more preferably 1 μm to 3 μm. A very thin retardation layer having a thickness of 1 μm to 3 μm can be manufactured from a liquid crystal cured layer in which a polymerizable liquid crystal compound is cured in an aligned state.

When laminating the polarizing film of the present invention and a λ/4 retardation layer, it is preferable to laminate them so that the slow axis (optical axis) of the λ/4 retardation layer and the absorption axis of the polarizer form substantially 45°. By laminating them so that the slow axis (optical axis) of the retardation layer and the absorption axis of the polarizer form substantially 45°, it is possible to obtain the function of an elliptical polarizing plate. Note that substantially 45° is usually in the range of 45±5°.

The elliptical polarizing plate of the present invention may have a configuration similar to that of a conventional general elliptical polarizing plate and/or retardation film. Examples of such configurations include an adhesive layer (sheet) for attaching the elliptical polarizing plate to a display element of an optical display, a protective film used to protect the surface of a polarizer or retardation layer from scratches and dirt, etc.

The elliptically polarizing plate of the present invention can be used in 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 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 flexible image display device, a touch panel display device, an electron emission display device (e.g., a field emission display device (FED), a surface field emission display device (SED)), an electronic paper (a display device using electronic ink or an electrophoretic element, a plasma display device, a projection display device (e.g., a display device having a grating light valve (GLV) display device, a digital micromirror device (DMD)), and a piezoelectric ceramic display. The liquid crystal display device includes any of a transmissive liquid crystal display device, a semi-transmissive liquid crystal display device, a reflective liquid crystal display device, a direct-view liquid crystal display device, and a projection liquid crystal display device. These display devices may be display devices that display two-dimensional images, or may be stereoscopic display devices that display three-dimensional images. In particular, the elliptical polarizing plate of the present invention can be suitably used for an organic electroluminescence (EL) display device.

In one embodiment of the present invention, the display device is preferably a flexible image display device, and the present invention also includes a flexible image display device that includes the elliptically polarizing plate of the present invention.

The flexible image display device having the elliptically polarizing plate of the present invention preferably further has a window and a touch sensor.
The flexible image display device is, for example, composed of a laminate for a flexible image display device and an organic EL display panel, and the laminate for a flexible image display device is disposed on the viewing side of the organic EL display panel and is configured to be foldable. The laminate for a flexible image display device may include a window, a (touch panel) touch sensor, etc., in addition to the above-mentioned elliptically polarizing plate of the present invention. The order of lamination of these is arbitrary, but it is preferable that they are laminated in the order of window, elliptically polarizing plate, and touch sensor, or the order of window, touch sensor, and elliptically polarizing plate from the viewing side.

It is preferable to have an elliptical polarizing plate on the visible side of the touch sensor, since the touch sensor pattern is less visible and the visibility of the displayed image is improved. Each member can be laminated using an adhesive, a pressure sensitive adhesive, or the like. The laminate for a flexible image display device can also be provided with a light blocking pattern formed on at least one surface of any of the layers of the window, the elliptical polarizing plate, and the touch sensor.

The window is disposed on the viewing side of the flexible image display device, and serves to protect the other components from external impacts or environmental changes such as temperature and humidity. Conventionally, glass has been used as such a protective layer, but the window in a flexible image display device is not rigid and hard like glass, but has flexible properties. The window is made of a flexible transparent substrate, and may include a hard coat layer on at least one surface.

The windows, touch sensors, etc. that make up the laminate for flexible image display devices are not particularly limited, and conventionally known ones may be used.

The present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited to the following examples. In the examples, "%" and "parts" mean mass % and mass parts, respectively, unless otherwise specified.

1. Example 1
(1) Preparation of composition for forming photo-alignment film Copolymer (1) was prepared according to the following procedure.
Copolymer (1)

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

The 4-((6-(methacryloyloxy)hexyl)oxy)phenyl(E)-3-(4-methoxyphenyl)acrylate (monomer that derives the photoreactive group-containing structural unit (i)) and 4-((6-(methacryloyloxy)hexyl)oxy)benzoic acid (monomer that derives the carboxy group-containing structural unit (iii)) were prepared according to the following procedure.

１，４－ジヒドロキシベンゼンと１，６－ジブロモヘキサンを、アルカリ条件下で加熱することにより、６－（４－ヒドロキシフェノキシ）－１－ブロモヘキサンを合成した。この生成物に、リチウムメタクリレートを反応させ、６－（４－ヒドロキシフェノキシ）ヘキシル メタクリレートを合成した。
これを、塩基性の条件下において、ｐ－メトキシ桂皮酸クロライドを加え、４－（（６－（メタクリロイルオキシ）ヘキシル）オキシ）フェニル （Ｅ）－３－（４－メトキシフェニル）アクリレートを合成した。 Monomer from which the photoreactive group-containing structural unit (i) is derived: 4-((6-(methacryloyloxy)hexyl)oxy)phenyl (E)-3-(4-methoxyphenyl)acrylate

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

Ｍａｋｒｏｍｏｌ．Ｃｈｅｍ．，１９０，ｐ２２５５－２２６８，１９８９に記載された方法を用い、メタクリル酸クロライドを原料として合成した。 Monomer from which the carboxyl group-containing structural unit (iii) is derived: 4-((6-(methacryloyloxy)hexyl)oxy)benzoic acid

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

Next, 2 parts of the obtained copolymer (1) was mixed with 98 parts of o-xylene, and the mixture was stirred at 80°C for 1 hour to obtain a composition for forming a photoalignment film.

(2) Preparation of a composition for forming a polarizer The following components were mixed and stirred for 1 hour at 80° C. to obtain a composition for forming a polarizer. The azo-based dye described in the examples of JP-A-2013-101328 was used as the dichroic dye.
75 parts of a polymerizable liquid crystal compound represented by formula (A-6)

25 parts of a polymerizable liquid crystal compound represented by formula (A-7):

2.8 parts of the dichroic dye (1) shown below

2.8 parts of the dichroic dye (2) shown below

2.8 parts of the dichroic dye (3) shown below

Polymerization initiator: 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one (Irgacure 369; manufactured by Ciba Specialty Chemicals) 6 parts Leveling agent: polyacrylate compound (BYK-361N; manufactured by BYK-Chemie) 1.2 parts Solvent: cyclopentanone 250 parts

(3) Preparation of polarizing plate A triacetyl cellulose film (KC4UY-TAC manufactured by Konica Minolta, Inc., thickness 40 μm) as a substrate was cut into a square shape and treated once using a corona treatment device (AGF-B10; manufactured by Kasuga Electric Co., Ltd.) under the conditions of an output of 0.3 kW and a treatment speed of 3 m/min. The photo-alignment film-forming composition was applied to the corona-treated surface with a bar coater, dried at 80° C. for 1 minute, and exposed to polarized UV light with an integrated light amount of 100 mJ/cm ² using a polarized UV irradiation device (SPOT CURE SP-7 with polarizer unit; manufactured by Ushio Inc.) to form a photo-alignment film. The thickness of the obtained photo-alignment film was measured with an ellipsometer M-220 (manufactured by JASCO Corporation) and found to be 100 nm.

A polarizer-forming composition was applied onto the obtained photo-alignment film using a bar coater, and then dried for 1 minute in a drying oven set at 100°C.

Thereafter, a high pressure mercury lamp (Uniqure VB-15201BY-A, manufactured by Ushio Inc.) was used to irradiate ultraviolet light (under a nitrogen atmosphere, wavelength: 365 nm, accumulated light amount at wavelength 365 nm: 1000 mJ/cm ² ) to form a polarizer in which the polymerizable liquid crystal compound and the dichroic dye were aligned, thereby obtaining a polarizing plate (1) consisting of a substrate/photo-aligned film/polarizer. At this time, the thickness of the polarizer was measured by an ellipsometer to be 1.0 μm.

(4) Property Evaluation [Evaluation of Adhesion]
The adhesion between the polarizer and the photo-alignment film in the obtained polarizing plate (1) was evaluated by the following method.

(Cross-hatch test)
The adhesion between the photo-alignment film and the polarizer in the obtained polarizing plate (1) was evaluated by a cross-hatch test in accordance with JIS D0202-1988 (JIS "checkerboard adhesion test"). A checkerboard pattern was created on the polarizer surface of the polarizing plate (1) by making scratches in a 10 x 10 checkerboard pattern at 2 mm intervals that penetrated to the polarizer and the photo-alignment film. An adhesive tape (25 mm wide, manufactured by Nichiban) was completely attached to the checkerboard surface. The adhesive tape was then peeled off in a direction at 90° to the surface.

The number of remaining squares that did not peel off was counted, and the adhesion was evaluated according to the following criteria. For the peeled squares, it was confirmed by X-ray photoelectron spectroscopy (XPS) that the peeled interface was between the photo-alignment film and the polarizer. The results are shown in Table 1.
<Evaluation criteria>
〇: 90 or more pieces △: 80 or more and 89 or less ×: 79 or less

[Evaluation of Orientation]
The obtained polarizing plate (1) was placed in a cross-Nicol arrangement through the polarizing plate from the backlight, and the orientation state of the polarizer was visually confirmed and the orientation was evaluated according to the following criteria. In addition, samples were separately prepared by drying the polarizer-forming composition for 1 minute in a drying oven set at a drying temperature of 110° C. or 120° C. in the same manner, and evaluated. The results are shown in Table 1.
<Evaluation criteria>
◯: No disturbance in orientation. ×: Disturbance in orientation or no orientation.

重合性基含有構造単位（ｉｉ）

カルボキシ基含有構造単位（ｉｉｉ）

2. Examples 2 to 7 and Comparative Example 1
Polarizing plates were prepared in the same manner as in Example 1, except that the composition of the copolymer forming the photo-alignment film was changed as shown in Table 1, and the adhesion and alignment properties were evaluated. The results are shown in Table 1.
The photoreactive group-containing structural unit (i), the polymerizable group-containing structural unit (ii), and the carboxy group-containing structural unit (iii) each have a structure derived from the following structure.
Photoreactive group-containing structural unit (i)

Polymerizable Group-Containing Structural Unit (ii)

Carboxy Group-Containing Structural Unit (iii)

As shown in Table 1, it was confirmed that the polarizing plates obtained in Examples 1 to 7 had high adhesion between the polarizer and the photo-alignment film. In contrast, the adhesion between the polarizer and the photo-alignment film of the polarizing plate obtained in Comparative Example 1 was insufficient.

Claims (11)

A polarizing film including a photo-alignment film and a polarizer adjacent to the photo-alignment film,
the photoalignment film is formed from a polymer including a structural unit having a photoreactive group and a structural unit having a polymerizable group,
The polymer forming the photoalignment film is represented by the formula (II):

[In the formula (II),
Ma, Mb and Mc represent monomer units forming the backbone of the copolymer;
m, n, and l represent mole fractions of the copolymer, with 0<m<1 and 0<n<1 and 0<l<1 in each case;
SPCRa, SPCRb, and SPCRc each independently represent a spacer unit;
Ring A, ring B and ring C are each independently an unsubstituted or substituted alicyclic hydrocarbon or an unsubstituted or substituted aromatic ring;
X is a single covalent bond, an alkylene chain having 1 to 10 carbon atoms, or a cycloalkylene chain having 3 to 8 carbon atoms;
Y is -O-CO-CH=CH ₂ - (either bond may be bonded to ring B), or -N=N-;
Z is selected from the group consisting of a single covalent bond; an alkylene chain having 1 to 10 carbon atoms which is unsubstituted or substituted with a hydroxyl group and/or a carbonyl group; a cycloalkylene chain having 3 to 8 carbon atoms; -O-; -COO-; and combinations thereof;
R ¹ is a phenyl group having at least one substituent selected from an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a cyano group, and a halogen atom;
R ² is -CW=CH ₂ or -V-CW=CH ₂ (wherein W is a hydrogen atom or a methyl group, and V is -O-CO- or -CO-).
The repeating unit has the following structure:
The weight average molecular weight of the polymer forming the photoalignment film is 50,000 or more and 150,000 or less,
The polarizer comprises a liquid crystal compound and a dichroic dye, and is a cured product of a liquid crystal composition containing a structural unit having a polymerizable group derived from the liquid crystal compound or the dichroic dye. The polarizing film according to claim 1, wherein the photoreactive group is a group that undergoes a dimerization reaction or an isomerization reaction. 3. The polarizing film according to claim 1, wherein the dichroic dye comprises an azo dye. 4. The polarizing film according to claim 1, wherein the polarizer comprises a polymer of a polymerizable liquid crystal compound. The polarizing film according to any one of claims 1 to 4 , wherein the polarizer exhibits a Bragg peak in X-ray diffraction measurement. A polarizing plate comprising the polarizing film according to any one of claims 1 to 5 and a substrate disposed on the photo-alignment film side of the polarizing film. 7. An optical laminate comprising the polarizing plate according to claim 6 and a layer attached to a polarizer side of the polarizing plate via a pressure-sensitive adhesive layer. 6. An elliptical polarizing plate comprising the polarizing film according to claim 1 and a retardation layer having a quarter-wave plate function. An organic electroluminescence display device comprising the elliptically polarizing plate according to claim 8 . A flexible image display comprising the elliptically polarizing plate according to claim 8 . The flexible visual display device of claim 10 further comprising a window and a touch sensor.