Liquid crystal alignment agents, liquid crystal alignment films and their manufacturing methods, liquid crystal elements, liquid crystal display devices, and polymers

Abstract

This invention provides a liquid crystal element with minimal change in liquid crystal alignment even after prolonged backlighting and high reliability. The liquid crystal alignment agent contains a polymer (P) having a partial structure represented by formula (1). In the formula, Rβ is a monovalent hydrocarbon group (1-10 carbon atoms), cyano, nitro, chlorine atom, bromine atom, iodine atom, -SiR2R3R4, -P(=O)R2R3, -C≡CR2, or -NR2R3; any methylene group in the monovalent hydrocarbon group (2-10 carbon atoms) is substituted with -O-, -S-, or -NR2- to form a monovalent group Rω1; or any hydrogen atom in the monovalent hydrocarbon group (1-10 carbon atoms) is substituted with a halogen atom, cyano, hydroxyl, amino, thiol, or nitro group to form a monovalent group. Rα is a hydrogen atom, a monovalent hydrocarbon group (1-10 carbon atoms), etc.

Description

Technical Field

[0001] This invention relates to a liquid crystal alignment agent, a liquid crystal alignment film and a method for manufacturing the same, a liquid crystal element, a liquid crystal display device, and a polymer. Prior Technology

[0002] In liquid crystal elements, liquid crystal alignment films are used to control the alignment of liquid crystal molecules in the liquid crystal layer. Liquid crystal alignment films are generally formed using liquid crystal alignment agents containing polymer components. Methods for obtaining organic films with liquid crystal alignment constraints have been known, including methods of rubbing the organic film, methods of oblique evaporation of silicon oxide, and methods of forming monolayers with long-chain alkyl groups. In addition, methods of irradiating photosensitive organic films with light (photoalignment methods) are also known.

[0003] Photoalignment can impart liquid crystal alignment properties to a film uniformly while suppressing the generation of static electricity or dust, and therefore various studies have been conducted in recent years (for example, see Patent Document 1 and Patent Document 2). Patent Document 1 and Patent Document 2 disclose the use of polymers having cinnamate ester structures to form liquid crystal alignment films by photoalignment.

[0004] [Existing technical documents] [Patent Literature] [Patent Document 1] International Publication No. 2007 / 071091 [Patent Document 2] International Publication No. 2016 / 080033 Summary of the Invention

[0005] [The problem the invention aims to solve] Compared to rubbing treatment, liquid crystal alignment films obtained through photoalignment treatment (photoalignment films) tend to have insufficient alignment constraint of liquid crystal molecules. Therefore, if the liquid crystal element is driven for a long time, changes in latency may sometimes be visible due to prolonged backlight exposure, or the initial alignment direction of the liquid crystal may gradually shift relative to its manufacturing origin. This change in alignment can manifest as image burn-in (image retention), reduced transmittance, or decreased black level. To meet the increasingly higher performance requirements of recent years, it is desirable to further improve display quality for liquid crystal elements.

[0006] The present invention was made in view of the above-mentioned problems, and its main objective is to provide a liquid crystal element with low change in liquid crystal alignment even after long-term backlighting and high reliability.

[0007] [Technical means to solve the problem] The following means are provided in accordance with the present invention.

[0008] <1> A liquid crystal alignment agent comprising a polymer (P) having a partial structure represented by the following formula (1). [Chemistry 1] In formula (1), Rβ is a monovalent hydrocarbon group with 1 to 10 carbon atoms, a cyano group, a nitro group, a chlorine atom, a bromine atom, an iodine atom, -SiR2R3R4, -P(=O)R2R3, -C≡CR2, or -NR2R3; a monovalent group Rω1 formed by substituting any methylene group in a monovalent hydrocarbon group with 2 to 10 carbon atoms with -O-, -S-, or -NR2-; or a monovalent group Rω1 or any hydrogen atom in a monovalent hydrocarbon group with 1 to 10 carbon atoms with halogen atoms, a cyano group, a hydroxyl group, an amino group, a thiol group, or a nitro group. Rα is a hydrogen atom, a monovalent hydrocarbon group with 1 to 10 carbon atoms, a cyano group, a nitro group, a halogen atom, -SiR2R3R4, -P(=O)R2R3, -COOR2, -C≡CR2, or -NR2R 3; A monovalent group Rω2 formed by substituting any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms with -O-, -S-, or -NR 2- substitution; or a monovalent group formed by substituting any hydrogen atom in a monovalent hydrocarbon group having 1 to 10 carbon atoms with a halogen atom, cyano, hydroxyl, amino, thiol, or nitro substitution. R2, R3, and R4 are each independently a hydrogen atom or a monovalent organic group. X1 is an oxygen atom or -NR 5-. R5 is a hydrogen atom or a monovalent organic group. R1 is a substituent. n is an integer from 0 to 4. m is 0 or 1. "*" indicates a bond.

[0009] <2> A method for manufacturing a liquid crystal alignment film includes: taking a liquid crystal alignment film according to the... <1> The steps of coating the liquid crystal alignment agent onto the substrate to form a coating film; and the step of irradiating the coating film with light. <3> A liquid crystal alignment film, using according to the... <1> It is formed by the liquid crystal alignment agent. <4> A liquid crystal element, comprising according to the... <3> The liquid crystal alignment film.

[0010] <5> A liquid crystal display device is disclosed, comprising a plurality of pixels, and including: a first substrate; a second substrate facing the first substrate; a liquid crystal layer disposed between the first substrate and the second substrate, and containing liquid crystal molecules; a first alignment film formed on the first substrate and aligning the liquid crystal molecules; and a second alignment film formed on the second substrate and aligning the liquid crystal molecules. In the liquid crystal display device, at least one of the first alignment film and the second alignment film is a photoalignment film. Each pixel in the plurality of pixels has a first alignment region, a second alignment region, a third alignment region, and a fourth alignment region as regions where the alignment orientations of the liquid crystal molecules are different from each other. The first alignment region, the second alignment region, the third alignment region, and the fourth alignment region are arranged along the long side direction of the pixel. The alignment orientations of the first alignment region, the second alignment region, the third alignment region, and the fourth alignment region are... In the alignment orientation of the fourth alignment region, the difference between any two alignment orientations is approximately an integer multiple of 90 degrees. The plurality of pixels are arranged along the short side of the pixel such that the alignment orientations of adjacent alignment regions are identical. In each alignment region of the first, second, third, and fourth alignment regions, one of the pretilt angles defined by the first alignment film and the pretilt angle defined by the second alignment film is less than 90 degrees, and the other is substantially 90 degrees. The photoalignment film is used according to... <1> It is formed by the liquid crystal alignment agent.

[0011] <6> An aggregate having a partial structure represented by the formula (1).

[0012] [The effects of the invention] Based on the above structure, a liquid crystal element with low change in liquid crystal alignment and high reliability can be obtained even after long-term backlight irradiation. Simple Explanation of the Diagram

[0013] Figure 1 is a schematic diagram showing the general structure of a liquid crystal display device. Figures 2(a) to 2(c) are diagrams showing an example of the alignment pattern in a pixel of a liquid crystal display device. Figures 3(a) and 3(b) are diagrams showing an example of the alignment pattern in each pixel of a liquid crystal display device. (a) shows the first substrate, and (b) shows the second substrate. Implementation

[0014] The following is a detailed description of matters related to the form of the present invention. Furthermore, in this specification, the term "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Chain hydrocarbon group" refers to a straight-chain hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure but is composed only of a chain structure. It can be saturated or unsaturated. "Alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only an alicyclic hydrocarbon structure as a ring structure and does not contain an aromatic ring structure. It is not necessary for it to be composed only of an alicyclic hydrocarbon structure; it may also include a group that has a chain structure in a portion thereof. "Aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. It is not necessary for it to be composed only of an aromatic ring structure; it may also include a chain structure or an alicyclic hydrocarbon structure in a portion thereof.

[0015] The term "aliphatic hydrocarbon group" encompasses both chain-like and alicyclic hydrocarbon groups. The "main chain" of a polymer refers to the longest segment of its atomic chain. The "side chain" of a polymer refers to the branching segments from the main chain. An "organic group" is a radical formed by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound). "(meth)acrylate" encompasses both acrylates and methacrylates. "(meth)acrylic acid" encompasses both acrylic acid and methacrylic acid.

[0016] "Liquid Crystal Alignment Agent" The liquid crystal alignment agent of the present invention contains a polymer (P) having a partial structure represented by the following formula (1). [Chemistry 2] In formula (1), Rβ is a monovalent hydrocarbon group with 1 to 10 carbon atoms, a cyano group, a nitro group, a chlorine atom, a bromine atom, an iodine atom, -SiR2R3R4, -P(=O)R2R3, -C≡CR2, or -NR2R3; a monovalent group Rω1 formed by substituting any methylene group in a monovalent hydrocarbon group with 2 to 10 carbon atoms with -O-, -S-, or -NR2-; or a monovalent group Rω1 or any hydrogen atom in a monovalent hydrocarbon group with 1 to 10 carbon atoms with halogen atoms, a cyano group, a hydroxyl group, an amino group, a thiol group, or a nitro group. Rα is a hydrogen atom, a monovalent hydrocarbon group with 1 to 10 carbon atoms, a cyano group, a nitro group, a halogen atom, -SiR2R3R4, -P(=O)R2R3, -COOR2, -C≡CR2, or -NR2R 3; A monovalent group Rω2 formed by substituting any methylene group in a monovalent hydrocarbon group having 2 to 10 carbon atoms with -O-, -S-, or -NR 2- substitution; or a monovalent group formed by substituting any hydrogen atom in a monovalent hydrocarbon group having 1 to 10 carbon atoms with a halogen atom, cyano, hydroxyl, amino, thiol, or nitro substitution. R2, R3, and R4 are each independently a hydrogen atom or a monovalent organic group. X1 is an oxygen atom or -NR 5-. R5 is a hydrogen atom or a monovalent organic group. R1 is a substituent. n is an integer from 0 to 4. m is 0 or 1. "*" indicates a bond.

[0017] <Aggregate (P)> The polymer (P) has a partial structure represented by formula (1) with a substituent (R β) at the β position of the carbonyl carbon. In formula (1), examples of monovalent hydrocarbon groups with 1 to 10 carbons represented by R β include: alkyl groups with 1 to 10 carbons, cycloalkyl groups with 3 to 10 carbons, aryl groups with 6 to 10 carbons, and aralkyl groups with 6 to 10 carbons.

[0018] Alkyl groups having 1 to 10 carbon atoms can be straight-chain or branched. Examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl. Cycloalkyl groups having 3 to 10 carbon atoms include cyclopentyl, cyclohexyl, and methylcyclohexyl. Aryl groups having 6 to 10 carbon atoms include phenyl and tolyl. Aryl alkyl groups having 6 to 10 carbon atoms include benzyl.

[0019] Specific examples of R β representing a monovalent hydrocarbon group having any methylene group having 2 to 10 carbon atoms substituted with -O-, -S-, or -NR 2- (R ω1) include: alkyl groups having 2 to 10 carbon atoms, cycloalkyl groups having 3 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, or aralkyl groups having one or more methylene groups having -O-, -S-, or -NR 2- substituted with methylene groups. Further specific examples of R ω1 include: alkoxy groups, alkoxyalkyl groups, groups having a (poly)alkyldiol chain, cycloalkoxy groups, arylalkoxy groups, aralkyloxy groups, etc.

[0020] When the group represented by Rβ is a monovalent hydrocarbon group with 1 to 10 carbon atoms, and any hydrogen atom is replaced by a halogen atom, examples of halogen atoms include: fluorine, chlorine, bromine, iodine, etc. Specific examples of monovalent groups represented by Rβ that are formed by the substitution of halogen atoms include: trifluoromethyl, perfluoroethyl, 2,2,2-trifluoroethyl, trichloromethyl, bromomethyl, etc.

[0021] Specific examples of monovalent groups formed by substituting any hydrogen atom of a monovalent hydrocarbon group having 1 to 10 carbon atoms with cyano, hydroxy, amino, thiol, or nitro groups as represented by Rβ include: cyanomethyl, aminomethyl, 2-aminoethyl, N-(aminomethyl)methyl, hydroxymethyl, 1-hydroxyethyl, 2-hydroxyethyl, hydroxymethyloxymethyl, thiolmethyl, 2-thiolethyl, nitromethyl, etc.

[0022] Examples of monovalent organic groups represented by R2, R3, and R4 include monovalent hydrocarbon groups having 1 to 10 carbon atoms and alkoxy groups having 1 to 10 carbon atoms. Specific examples of monovalent hydrocarbon groups having 1 to 10 carbon atoms include groups identical to those exemplified in the description of groups represented by Rβ. Examples of alkoxy groups having 1 to 10 carbon atoms include methoxy, ethoxy, propoxy, butoxy, and pentoxy.

[0023] In terms of obtaining a liquid crystal element that is not easily degraded even after prolonged exposure to backlight and has high reliability, Rβ is preferably a monovalent hydrocarbon group with 1 to 10 carbon atoms, a cyano group, a nitro group, a chlorine atom, a bromine atom, an iodine atom, -SiR2R3R4, -P(=O)R2R3, -C≡CR2, or -NR2R3; a monovalent group Rω1 formed by substituting any methylene group in the monovalent hydrocarbon group with 2 to 10 carbon atoms with -O-, -S-, or -NR2-; or a monovalent group formed by substituting any hydrogen atom in the monovalent hydrocarbon group with 1 to 10 carbon atoms with a halogen atom, a cyano group, or a nitro group, preferably an alkyl group with 1 to 6 carbon atoms, a fluoroalkyl group with 1 to 6 carbon atoms, a trialkylsilyl group, a cyano group, a bromine atom, an iodine atom, or -NR12R13 (wherein, R12 and R R13 is independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, or contains a -O-, -S-, or -NR2- monovalent group between carbon-carbon bonds of a monovalent hydrocarbon group having 2 to 10 carbon atoms (wherein R2 is a hydrogen atom or a monovalent organogroup). Among these, Rβ is particularly preferably an alkyl group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms, a trialkylsilyl group, or -NR12R13, and even more preferably a methyl, ethyl, or trialkylsilyl group.

[0024] The partial structure represented by formula (1) has a hydrogen atom or substituent at the α position of the carbonyl carbon. Specific examples of R α in formula (1) being a monovalent hydrocarbon group having 1 to 10 carbon atoms, -SiR 2R 3R 4, -P(=O)R 2R 3, -C≡CR 2 or -NR 2R 3, a radical R ω2, or a monovalent group formed by substituting any hydrogen atom of a radical R ω2 or a monovalent hydrocarbon group having 1 to 10 carbon atoms with a halogen atom, cyano or nitro group, can be listed as groups identical to those exemplified as R β. Specific examples of R α being a halogen atom include: fluorine atom, chlorine atom, bromine atom, iodine atom, etc. Specific examples of "-COOR 2" include: alkyloxycarbonyl, cycloalkyloxycarbonyl, aryloxycarbonyl, etc.

[0025] In terms of obtaining a liquid crystal element with minimal change in liquid crystal alignment even after prolonged exposure to backlight and high reliability, the group represented by Rα is preferably a monovalent group formed by substituting any methylene group from a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a cyano group, or a monovalent hydrocarbon group having 2 to 10 carbon atoms with -O-, -S-, or -NR2- substitution (where R2 is a hydrogen atom or a monovalent organic group), more preferably a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or a cyano group, and even more preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a cyano group, and even more preferably a hydrogen atom.

[0026] When the group represented by X1 is -NR5-, examples of monovalent organic groups represented by R5 include monovalent hydrocarbon groups having 1 to 10 carbon atoms and monovalent thermally detachable groups. Specific examples of R5 being a monovalent hydrocarbon group include alkyl groups having 1 to 6 carbon atoms, cycloalkyl groups having 4 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and aralkyl groups having 6 to 10 carbon atoms. Among these, alkyl groups having 1 to 6 carbon atoms, cycloalkyl groups, and phenyl groups are more preferred, and alkyl groups having 1 to 3 carbon atoms are even more preferred. Furthermore, R5 can also be a ring structure formed by bonding with other groups and together with the nitrogen atom bonded to R5. Examples of such ring structures include piperidine structures and piperazine structures.

[0027] When R5 is a monovalent thermally detachable group, it is more preferably a monovalent group that detaches due to heating during film formation. Specific examples of thermally detachable groups include: tert-butoxycarbonyl (Boc group), benzyloxycarbonyl, 1,1-dimethyl-2-haloethyloxycarbonyl, allyloxycarbonyl, 2-(trimethylsilyl)ethoxycarbonyl, etc. Among these, the Boc group is particularly preferred in terms of excellent thermally detachable properties and the reduction of the amount of detached structure remaining in the film.

[0028] In terms of further improving the photoalignment of the partial structure represented by formula (1), X1 is preferably an oxygen atom, -NH-, -N(CH3)- or -NR15- (R15 is a Boc group), and more preferably an oxygen atom.

[0029] Examples of substituents for R1 include: alkyl groups with 1 to 5 carbon atoms, alkoxy groups with 1 to 5 carbon atoms, halogen atoms, hydroxyl groups, carboxyl groups, amino groups, cyano groups, alkylsilyl groups, alkoxysilyl groups, ester groups, etc. n is preferably 0 to 2, more preferably 0 or 1, and even more preferably 0. Furthermore, when m is 1, the bond (*) in formula (1) represents a bond bonded to other groups (organic groups). When m is 1, the bond (*) in formula (1) can be bonded to atoms constituting the main chain of the polymer or to atoms constituting the side chain. When m is 0, the partial structure represented by formula (1) can exist at the end of the polymer main chain or at the end of the side chain.

[0030] The main framework of polymer (P) is not particularly limited. From the viewpoint of good heat resistance or mechanical strength, affinity for liquid crystals, etc., polymer (P) is preferably selected from at least one of the group consisting of polyamide, polyimide, polyamide ester, polyorganosiloxane and addition polymer. Polymer (P) may have the partial structure represented by formula (1) in the main chain, or the partial structure in the side chain, or the partial structure in both the main chain and the side chain. Hereinafter, a preferred example of polymer (P) will be described.

[0031] [Polyamide] Polyamide (hereinafter also referred to as "polyamide (P)") as polymer (P) can be obtained by polymerization using a monomer having a partial structure represented by the formula (1). Examples of methods for manufacturing polyamide (P) include: [1] a method for polymerizing a monomer containing a tetracarboxylic dianhydride (hereinafter also referred to as "specific acid dianhydride") having a partial structure represented by the formula (1); [2] a method for polymerizing a monomer containing a diamine (hereinafter also referred to as "specific diamine") having a partial structure represented by the formula (1); [3] a method for polymerizing a monomer containing a specific acid dianhydride and a specific diamine, etc. Of these, the use of a specific diamine is preferred in terms of ease of monomer synthesis, and the method described in [2] is even more preferred.

[0032] (Tetracarboxylic acid dianhydride) ·Specific acid dianhydrides The structure of other parts of a specific acid dianhydride is not particularly limited as long as it has the partial structure represented by formula (1). Preferably, the specific acid dianhydride has the partial structure represented by formula (1) in its main chain. Specific examples of specific acid dianhydrides include compounds represented by formulas (5-1) to (5-4) respectively. [Chemistry 3]

[0033] Other acid dianhydrides In the cases of methods [1] and [3], the tetracarboxylic dianhydride used in the synthesis of polyacrylic acid (P) may be only a specific acid dianhydride, but may also be a tetracarboxylic dianhydride that does not have the partial structure represented by formula (1) (hereinafter also referred to as "other acid dianhydrides"). In method [2], other acid dianhydrides are used as tetracarboxylic dianhydrides in the synthesis of polyacrylic acid (P). Examples of other acid dianhydrides include aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides. Examples of aliphatic tetracarboxylic dianhydrides include chain tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides.

[0034] Specific examples of them include 1,2,3,4-butanetetracarboxylic dianhydrides, etc. Examples of alicyclic tetracarboxylic dianhydrides include: 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxylated cyclopentylacetic dianhydride, 5-(2,5-dioxotetrahydrofuran-3-yl)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 2,4,6,8-tetracarboxylated bicyclo[3.3.0]octane-2:4,6:8-dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, etc. Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 4,4'-(hexafluoroisopropylidene)phthalic anhydride, ethylene glycol bis(triphenyl)phthalic anhydride, and 4,4'-carbonyl phthalic anhydride. In addition, tetracarboxylic dianhydrides described in Japanese Patent Application Publication No. 2010-97188 may be used. One tetracarboxylic dianhydride may be used alone or in combination of two or more.

[0035] Regarding the improvement of the solubility of the polymer and the acquisition of a liquid crystal alignment film exhibiting good electrical properties, the tetracarboxylic dianhydride used in the synthesis of polyacrylic acid is preferably at least one selected from the group consisting of chain-like tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides, and more preferably alicyclic tetracarboxylic dianhydrides. The amount of alicyclic tetracarboxylic dianhydride used is preferably 20 mol% or more, more preferably 40 mol% or more, and more preferably 50 mol% or more, relative to the total amount of tetracarboxylic dianhydrides used in the synthesis of polyacrylic acid.

[0036] (Diamine) ·Specific diamine The specific diamine used in the synthesis of polyamide (P) is not particularly limited as long as it has the partial structure represented by formula (1). The specific diamine may have the partial structure represented by formula (1) in the main chain or in the side chain. Examples of specific diamines include compounds represented by formula (6-1) and compounds represented by formula (6-2) below. [Chemistry 4] (In formula (6-1), A1 is the divalent group represented by formula (1). Y1 and Y2 are independently single bonds or divalent organic groups, respectively.) [Chemistry 5] (In formula (6-2), A2 is the divalent group represented by formula (1). Y3 is a trivalent aromatic cyclic group. Y4 is a single bond or a divalent linker. Y5 is a hydrogen atom or a monovalent organic group.)

[0037] In formula (6-1), examples of divalent organic groups represented by Y1 and Y2 include: divalent hydrocarbon groups with 1 to 20 carbon atoms; divalent groups and divalent heterocyclic groups formed by substituting a portion of the methylene group with -O-, -CO-, -COO-, or -NR 30- (where R 30 is a hydrogen atom or an alkyl group with 1 to 6 carbon atoms); these groups may also have substituents. Examples of divalent heterocyclic groups include groups obtained by removing two hydrogen atoms from nitrogen-containing heterocycles such as pyridine, piperazine, and piperidine. Examples of substituents that Y1 and Y2 may have include: halogen atoms, alkoxy groups, hydroxyl groups, carboxyl groups, cyano groups, nitro groups, etc.

[0038] In formula (6-2), the trivalent aromatic ring group represented by Y3 is a group obtained by removing three hydrogen atoms from the ring portion of an aromatic ring. Examples of such aromatic rings include: aromatic hydrocarbon rings such as benzene rings, naphthalene rings, and anthracene rings; and aromatic heterocycles such as pyridine rings and pyridazine rings. Among these, benzene rings and pyridine rings are particularly preferred. Furthermore, substituents may be introduced into the aromatic ring of the aromatic ring group. Examples of such substituents include: alkyl groups having 1 to 3 carbon atoms, halogen atoms, and hydroxyl groups.

[0039] Examples of divalent linkages represented by Y4 include: -O-, -CO-, -COO-, -NR 30-, -CO-NR 30-, and alkyl diols with 1 to 3 carbon atoms.

[0040] Examples of monovalent organic groups represented by Y 5 include: monovalent hydrocarbon groups with 1 to 20 carbon atoms, monovalent groups formed by substituting a portion of the methylene group with -O-, -CO-, -COO- or -NR 30-, monovalent heterocyclic groups, etc., which may also have substituents.

[0041] As specific examples of a particular diamine, the compounds represented by formula (6-1) may include, for example, the compounds represented by formulas (6-1-1) to (6-1-22) below; the compounds represented by formula (6-2) may include, for example, the compounds represented by formulas (6-2-1) to (6-2-4) below. [Chemistry 6] [Chemistry 7] [Chemistry 8] [Chemistry 9]

[0042] [Chemistry 10]

[0043] Other diamines In methods [2] and [3], the diamine used in the synthesis of polyacrylic acid (P) may be only a specific diamine, but may also include diamines that do not have the partial structure represented by formula (1) (hereinafter also referred to as "other diamines"). In method [1], other diamines are used as diamines in the synthesis of polyacrylic acid (P). Examples of other diamines include aliphatic diamines, aromatic diamines, and diamino organosilicones. Examples of aliphatic diamines include chain diamines and alicyclic diamines.

[0044] Specific examples of diamines used in the synthesis of polyamides include: m-phenylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, etc. Examples of alicyclic diamines include: 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), etc. Aromatic diamines include: p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4-aminophenyl-4-aminobenzoic acid ester, 4,4'-diaminoazobenzene, 3,5-diaminobenzoic acid, 1,5-bis(4-aminophenoxy)pentane, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,6-bis(4-aminophenoxy)hexane, bis[2-(4-aminophenyl)ethyl]adipic acid, 2,6-diaminopyridine, 1,4-bis-(4-aminophenyl)piperazine, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis(triphenyl)-diaminodiphenylmethane, etc. Main-chain diamines include fluoromethyl)-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(phenylene diisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-[4,4'-propane-1,3-diylbis(piperidine-1,4-diyl)]diphenylamine, 4,4'-diaminobenzylaniline, 4,4'-diaminostyrylbenzene, and 1,4-bis(4-aminophenyl)-piperazine; Dodecyloxy-2,4-diaminobenzene, pentadecyloxy-2,4-diaminobenzene, hexadecyloxy-2,4-diaminobenzene, octadecyloxy-2,4-diaminobenzene, pentadecyloxy-2,5-diaminobenzene, octadecyloxy-2,5-diaminobenzene, cholesteryloxy-3,5-diaminobenzene, cholesteryloxy-3,5-diaminobenzene, cholesteryloxy-2,4-diaminobenzene, cholesteryloxy-2,4-diaminobenzene, cholesteryl 3,5-diaminobenzoate Alkyl ester, 3,5-diaminobenzoic acid cholesterol, 3,5-diaminobenzoic acid lanosteryl ester, 3,6-bis(4-aminobenzoyloxy)cholestan, 3,6-bis(4-aminophenoxy)cholestan, 4-(4'-trifluoromethoxybenzoyloxy)cyclohexyl-3,5-diaminobenzoic acid ester, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, 3,5-diaminobenzoic acid =5ξ-cholestan-3-yl, and the following formula (E-1) [Chemistry 11] (In formula (E-1), XI and XII independently represent a single bond, -O-, *-COO-, or *-OCO- (where "*" indicates a bond with XI). RI is an alkyldiyl group with 1 to 3 carbon atoms. RII is a single bond or an alkyldiyl group with 1 to 3 carbon atoms. RIII is an alkyl, alkoxy, fluoroalkyl, or fluoroalkoxy group with 1 to 20 carbon atoms. a is 0 or 1. b is an integer from 0 to 3. c is an integer from 0 to 2. d is 0 or 1. Wherein, 1 ≦ a + b + c ≦ 3.) The compounds represented include side-chain diamines, etc. Examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, and the diamine described in Japanese Patent Application Publication No. 2010-97188 may also be used.

[0045] In addition, other diamines include -NR- (where R is a monovalent hydrocarbon group or a thermally detachable group with 1 to 10 carbon atoms) or diamines having a nitrogen-containing heterocyclic structure (hereinafter also referred to as "nitrogen-containing diamines"). Besides the corresponding compounds among the other diamines listed above, other nitrogen-containing diamines include, for example: N4,N4'-bis-(4-aminophenyl)-N4,N4'-dimethylbiphenyl-4,4'-diamine, N,N'-bis(5-amino-2-pyridyl)-N,N'-bis(tert-butoxycarbonyl)ethylenediamine, 6,6'-(pentamethylenedioxy)bis(3-aminopyridine), 3,5-diamino-N,N-bis(pyridin-3-ylmethyl)benzylamine, 4-(4-aminophenoxycarbonyl)-1-(4-aminophenyl)piperidine, etc. In the synthesis of polyamide (P), one or more diamines can be used alone or in combination as specific diamines.

[0046] In polyacrylic acid (P), the proportion of the partial structure represented by formula (1) is preferably 5 mol% or more, more preferably 10 mol% or more, and more preferably 15 mol% or more, relative to all diamine units contained in polyacrylic acid (P). Furthermore, the proportion of the partial structure represented by formula (1) in polyacrylic acid (P) is preferably 95 mol% or less, more preferably 90 mol% or less, and more preferably 85 mol% or less, relative to all diamine units contained in polyacrylic acid (P). If the proportion of the partial structure represented by formula (1) in polyacrylic acid (P) is within the aforementioned range, the polyacrylic acid (P) exhibits good photoreactivity and can form an alignment film that shows good liquid crystal alignment even after prolonged exposure to backlight; in this respect, it is even more preferable.

[0047] Synthesis of polyacrylic acid Polyacrylic acid (P) can be obtained by reacting a tetracarboxylic dianhydride as described above with a diamine and, if necessary, a molecular weight adjuster. The preferred ratio of tetracarboxylic dianhydride to diamine used in the synthesis of polyacrylic acid (P) is 1 equivalent of the amino group of the diamine and 0.2 to 2 equivalents of the anhydride group of the tetracarboxylic dianhydride.

[0048] Examples of molecular weight modifiers include: maleic anhydride, phthalic anhydride, itaconic anhydride, and other monohydric anhydrides; aniline, cyclohexylamine, n-butylamine, and other monoamine compounds; and phenyl isocyanate, naphthyl isocyanate, and other monoisocyanate compounds. The proportion of the molecular weight modifier used is preferably set to 20 parts by mass or less, relative to the total 100 parts by mass of the tetracarboxylic dianhydride and diamine used.

[0049] The synthesis reaction of polyacrylic acid (P) is preferably carried out in an organic solvent. The reaction temperature is preferably -20°C to 150°C, and the reaction time is preferably 0.1 h to 24 h. Examples of organic solvents used in the reaction include: aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons. Particularly preferred organic solvents are one or more selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphoric acid triamine, m-cresol, xylenol, and halogenated phenols, or mixtures of these or more with other organic solvents (e.g., butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount of organic solvent used (a) is preferably set as the total amount (b) of tetracarboxylic acid dianhydride and diamine relative to the total amount (a+b) of the reaction solution, which is 0.1% to 50% by mass.

[0050] A reaction solution containing polyacrylic acid (P) is obtained in the manner described above. The reaction solution can be used directly for the preparation of liquid crystal alignment agents, or it can be used for the preparation of liquid crystal alignment agents after separating the polyacrylic acid (P) contained in the reaction solution.

[0051] (Polyamide) Polyamide esters (hereinafter also referred to as "polyamide ester (P)") as polymers (P) can be obtained, for example, by methods such as: [I] reacting polyamide ester (P) obtained by the synthesis reaction with an esterifying agent; [II] reacting a tetracarboxylic acid diester with a diamine containing a specific diamine; [III] reacting a tetracarboxylic acid diester dihalide with a diamine containing a specific diamine. The polyamide ester (P) contained in the liquid crystal alignment agent of the present invention may have only an amide ester structure, or it may be a partial esterification with both an amide ester structure and an amide ester structure. The reaction solution obtained by dissolving polyamide ester (P) can be directly used in the preparation of the liquid crystal alignment agent, or it can be used in the preparation of the liquid crystal alignment agent after separating the polyamide ester (P) contained in the reaction solution.

[0052] (Polyimide) Polyimide (hereinafter also referred to as "polyimide (P)") as polymer (P) can be obtained, for example, by dehydrating and ring-closing polyamide (P) synthesized in the manner described above and then amide-imidizing it. Polyimide (P) can be a fully amided compound obtained by dehydrating and ring-closing all the amide structures of the polyamide (P) as its precursor, or it can be a partially amided compound obtained by dehydrating and ring-closing only a portion of the amide structure, resulting in the coexistence of amide and amide ring structures. The amide-imidization rate of polyimide (P) is preferably 20% or more, more preferably 30% to 95%. The amide-imidization rate is expressed as a percentage representing the proportion of the number of amide ring structures relative to the total number of amide structures and amide ring structures in the polyimide. Here, a portion of the aceimine ring may be an isoaceimine ring.

[0053] The dehydration and ring-closure of polyacrylic acid (P) is preferably carried out by dissolving polyacrylic acid (P) in an organic solvent, adding a dehydrating agent and a dehydration and ring-closure catalyst to the solution, and heating as needed. In this method, anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used as dehydrating agents. The amount of dehydrating agent used is preferably 0.01 mol to 20 mol relative to 1 mol of the polyacrylic acid structure of polyacrylic acid (P). Tertiary amines such as pyridine, trimethylpyridine, dimethylpyridine, and triethylamine can be used as dehydration and ring-closure catalysts. The amount of dehydration and ring-closure catalyst used is preferably 0.01 mol to 10 mol relative to 1 mol of the dehydrating agent used. Examples of organic solvents used in the synthesis of polyacrylic acid (P) can be cited as examples of organic solvents used in the dehydration and ring-closure reaction. The reaction temperature of the dehydration and ring-closure reaction is preferably 0°C to 180°C. The reaction time is preferably 1.0 hour to 120 hours. Furthermore, the reaction solution containing the polyimide (P) obtained by the above reaction can be used directly in the preparation of liquid crystal alignment agents, or it can be used in the preparation of liquid crystal alignment agents after the polyimide (P) is separated. Alternatively, polyimide (P) can also be obtained by amide imidization of polyamide ester (P).

[0054] Regarding the solution viscosity of polyamide, polyamide ester, and polyimide contained in the liquid crystal alignment agent, when preparing a 10% by mass solution, a solution viscosity of 10 mPa·s to 800 mPa·s is preferred, and a solution viscosity of 15 mPa·s to 500 mPa·s is even more preferred. Furthermore, the solution viscosity (mPa·s) is a value obtained by measuring a 10% by mass polymer solution prepared using a type E rotational viscometer at 25°C with a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0055] The weight-average molecular weight (Mw) of polystyrene, determined by gel permeation chromatography (GPC) for polyamides, polyamide esters, and polyimides, is preferably 1,000 to 500,000, more preferably 5,000 to 100,000. The molecular weight distribution (Mw / Mn), expressed as the ratio of Mw to the number-average molecular weight (Mn) of polystyrene determined by GPC, is preferably 15 or less, more preferably 10 or less.

[0056] (Polyorganosiloxane) The method of manufacturing a polyorganosiloxane (hereinafter also referred to as "polysiloxane (P)") as a polymer (P) is not particularly limited as long as it has the partial structure represented by the formula (1). Polysiloxane (P) can be obtained, for example, by hydrolysis / condensation reaction of a hydrolyzable silica compound. Specifically, the methods described in [1] and [2] below can be cited.

[0057] [1] A method for synthesizing an epoxy-containing polyorganosiloxane by hydrolyzing and condensing an epoxy-containing hydrolyzable silane compound (ms-1) or a mixture of silane compound (ms-1) and other silane compounds, and then reacting the obtained epoxy-containing polyorganosiloxane with a carboxylic acid having a partial structure represented by the formula (1) (hereinafter also referred to as "specific carboxylic acid"). [2] A method for hydrolyzing and condensing a hydrolytic silane compound (ms-2) having a partial structure represented by formula (1), or a mixture of silane compound (ms-2) and other silane compounds. Of these, the method of [1] is simple and can improve the incorporation rate of the partial structure represented by formula (1) in polysiloxane (P), which is better in this respect.

[0058] Specific examples of silane compounds (ms-1) include: 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-glycidoxyethyltrimethoxysilane, 2-glycidoxyethylmethyldimethoxysilane, 2-glycidoxyethyldimethylmethoxysilane, 2-glycidoxyethyldimethylmethoxysilane, 2-glycidoxyethyldimethylethoxysilane. Silanes, including 4-glycidoxybutyltrimethoxysilane, 4-glycidoxybutylmethyldimethoxysilane, 4-glycidoxybutylmethyldiethoxysilane, 4-glycidoxybutyldimethylmethoxysilane, 4-glycidoxybutyldimethylethoxysilane, 4-glycidoxybutyldimethylethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, and 3-(3,4-epoxycyclohexyl)propyltrimethoxysilane, etc. As a silane compound (ms-1), one or more of these can be used.

[0059] There are no particular limitations on other silane compounds used in the synthesis of epoxy-containing polyorganosiloxanes, as long as they exhibit hydrolytic properties. Specific examples include, for instance, alkoxysilanes such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane. 3-Mercaptopropyltrimethoxysilane, 3-Mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, 3-ureapropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(3-cyclohexylamino)propyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and other nitrogen / sulfur-containing alkoxysilanes; 3-(meth)propenylated propyltrimethoxysilane, 3-(meth)propenyloxypropyltriethoxysilane, 6-(meth)propenyloxyhexyltrimethoxysilane, 3-(meth)propenyloxypropylmethyldimethoxysilane, 3-(meth)propenyloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, and other alkoxysilanes containing unsaturated hydrocarbons, and in addition, trimethoxysilylpropylsuccinic anhydride, etc., may be listed. Other silane compounds may be used alone or in combination of two or more. Furthermore, in this specification, "(meth)propenyloxy" includes both "propenyloxy" and "methpropenyloxy".

[0060] The hydrolysis / condensation reaction of silane compounds can be carried out by reacting one or more of the silane compounds described above with water, preferably in the presence of a suitable catalyst and an organic solvent. During the reaction, the ratio of water used is preferably 1 to 30 mol relative to 1 mol of the total silane compound (total mass). Examples of catalysts used include acids, alkali metal compounds, organic bases, titanium compounds, zirconium compounds, etc. The amount of catalyst used varies depending on the type of catalyst, reaction conditions such as temperature, etc., and should be appropriately set; for example, it is preferably 0.01 to 3 mol relative to the total silane compound. Examples of organic solvents used include hydrocarbons, ketones, esters, ethers, alcohols, etc. Among these, it is preferable to use an organic solvent that is insoluble in water or poorly soluble in water. The ratio of organic solvent used is preferably 10 to 10,000 parts by mass relative to 100 parts by mass of the total silane compound used in the reaction.

[0061] The hydrolysis / condensation reaction is preferably carried out by heating, for example, in an oil bath. In this case, the heating temperature is preferably set below 130°C, and the heating time is preferably set to 0.5 hours to 12 hours. After the reaction is complete, the organic solvent layer separated from the reaction solution is dried with a desiccant as needed to remove the solvent, thereby obtaining the target polysiloxane. Furthermore, the synthesis method of polysiloxane is not limited to the hydrolysis / condensation reaction described above; for example, it can also be carried out by reacting hydrolyzable silane compounds in the presence of oxalic acid and alcohol.

[0062] In the method described in [1], the epoxy-containing polyorganosiloxane obtained by the reaction is then reacted with a specific carboxylic acid. Thus, the epoxy groups of the epoxy-containing polyorganosiloxane react with the carboxyl groups of the specific carboxylic acid to obtain a polyorganosiloxane (P) having a partial structure represented by the formula (1) in the side chain.

[0063] Specific examples of a particular carboxylic acid include, for example, the compounds represented by formulas (7-1) to (7-5) below. [Chemistry 12]

[0064] In a molecule of polysiloxane (P), the proportion of the partial structure represented by formula (1) relative to the number of silicon atoms in polysiloxane (P) is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more. Furthermore, in a molecule of polysiloxane (P), the proportion of the partial structure represented by formula (1) relative to the number of silicon atoms in polysiloxane (P) is preferably 70 mol% or less, more preferably 60 mol% or less, and even more preferably 50 mol% or less. If the proportion of the partial structure represented by formula (1) in polysiloxane (P) is within the aforementioned range, it is more advantageous in terms of the good photoreactivity of polysiloxane (P) and the formation of an alignment film that exhibits good liquid crystal alignment even after prolonged exposure to backlight.

[0065] Furthermore, in the synthesis of polysiloxanes (P), the carboxylic acid used in the reaction with the epoxy-containing polyorganosiloxane may be a specific carboxylic acid, but other carboxylic acids besides the specific carboxylic acid may also be used. Any other carboxylic acid can be used as long as it does not have the partial structure represented by formula (1). Examples of other carboxylic acids include, for instance, carboxylic acids with a mesocrystalline structure.

[0066] The reaction of epoxy-containing polyorganosiloxanes with carboxylic acids is preferably carried out in the presence of a catalyst and an organic solvent. As the catalyst used, for example, compounds known as curing accelerators that promote the reaction of organic bases and epoxy compounds (e.g., tertiary organic amines, quaternary organic amines, quaternary ammonium salts, etc.) can be used. The amount of catalyst used is preferably less than 100 parts by mass relative to 100 parts by mass of the epoxy-containing polyorganosiloxane, more preferably 0.1 to 20 parts by mass.

[0067] Examples of organic solvents used in the reaction include hydrocarbons, ethers, esters, ketones, amides, and alcohols. Preferably, the organic solvent is used at a concentration of 0.1% by mass or more (the ratio of the total mass of components other than the solvent in the reaction solution to the total mass of the solution), more preferably at a concentration of 5% to 50% by mass. In the reaction, the reaction temperature is preferably 0°C to 200°C, more preferably 50°C to 150°C. The reaction time is preferably 0.1 hours to 50 hours, more preferably 0.5 hours to 20 hours. After the reaction is complete, it is preferable to wash the organic solvent layer separated from the reaction solution with water. After washing with water, the organic solvent layer is dried with a suitable desiccant if necessary, and the solvent is removed, thereby obtaining the polysiloxane (P) as the target material.

[0068] The polysiloxane (P) preferably has a solution viscosity of 1 mPa·s to 500 mPa·s when prepared as a 10% by mass solution, more preferably a solution viscosity of 3 mPa·s to 200 mPa·s. Regarding the polysiloxane (P), the weight-average molecular weight (Mw) of the polystyrene, as determined by GPC, is preferably 1,000 to 200,000, more preferably 2,000 to 50,000, and even more preferably 3,000 to 20,000.

[0069] (Addition polymer) The method of manufacturing an addition polymer (hereinafter also referred to as "addition polymer (P)") is not particularly limited as long as it has the partial structure represented by the formula (1). An addition polymer (P) is a polymer having structural units derived from monomers having polymerizable carbon-carbon unsaturated bonds. An addition polymer (P) can be obtained, for example, by polymerizing an unsaturated monomer (ma-1) having the partial structure represented by the formula (1), or a mixture of an unsaturated monomer (ma-1) and other unsaturated monomers.

[0070] As an unsaturated monomer, any monomer having polymerizable carbon-carbon unsaturated bonds can be used. Examples of such monomers include compounds having (meth)acrylic, vinyl, vinylphenyl, and maleimide groups. Regarding the formation of liquid crystal alignment films with excellent liquid crystal alignment properties, at least one selected from the group consisting of poly(meth)acrylates, maleimide polymers, and styrene-maleimide copolymers is more preferably used as the unsaturated polymer (P).

[0071] The unsaturated monomer (ma-1) is only required to have the partial structure represented by formula (1), and there is no particular limitation. Specific examples of unsaturated monomers (ma-1) include compounds represented by formulas (8-1) to (8-10) respectively. [Chemistry 13] (In formulas (8-1) to (8-4), R is a hydrogen atom or a methyl group.) [Chemistry 14]

[0072] Other specific examples of unsaturated monomers include: unsaturated carboxylic acids such as (meth)acrylic acid, α-ethylacrylic acid, maleic acid, fumaric acid, and vinylbenzoic acid; unsaturated carboxylic acid esters such as alkyl (meth)acrylates (e.g., methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cycloalkyl (meth)acrylates, benzyl (meth)acrylate, trimethoxysilylpropyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, glycidyl (meth)acrylate, 3,4-epoxycyclohexyl methyl (meth)acrylate, 3,4-epoxybutyl (meth)acrylate, and 4-hydroxybutyl glycidyl (meth)acrylate; and unsaturated polycarboxylic anhydrides such as maleic anhydride, etc., and other (meth)acrylic acid compounds. Aromatic vinyl compounds such as styrene, methylstyrene, divinylbenzene, and 4-(glycidoxymethyl)styrene; conjugated diene compounds such as 1,3-butadiene and 2-methyl-1,3-butadiene; N-Methylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, 4-(2,5-dioxo-3-pyrrololin-1-yl)benzoic acid, N-(4-glycidyloxyphenyl)maleimide, N-glycidylmaleimide, 3-maleimidebenzoic acid, 3-maleimidepropionic acid, 3-(2,5-dioxo-3-pyrrololin-1-yl)benzoic acid, and methyl 4-(2,5-dioxo-3-pyrrololin-1-yl)benzoate, etc., are maleimide compounds. In the synthesis of addition polymers (P), they can be used alone or in combination as other unsaturated monomers.

[0073] In one molecule of the addition polymer (P), the proportion of the partial structure represented by formula (1) is preferably 1 mol% or more, more preferably 2 mol% or more, and even more preferably 5 mol% or more, relative to all the structural units of the addition polymer (P). Furthermore, in one molecule of the addition polymer (P), the proportion of the partial structure represented by formula (1) is preferably 60 mol% or less, more preferably 50 mol% or less, and even more preferably 40 mol% or less, relative to all the structural units of the addition polymer (P). If the proportion of the partial structure represented by formula (1) in the addition polymer (P) is within the aforementioned range, the addition polymer (P) can exhibit good photoreactivity, and an alignment film exhibiting good liquid crystal alignment even after prolonged exposure to backlight can be formed, which is more preferable than the above.

[0074] Addition polymers (P) can be obtained, for example, by polymerizing monomers in the presence of a polymerization initiator. Preferably, the polymerization initiator used is an azo compound such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), or 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile). The proportion of the polymerization initiator used is preferably set to 0.01 to 30 parts by mass relative to 100 parts by mass of all monomers used in the reaction.

[0075] The polymerization reaction is preferably carried out in an organic solvent. Examples of organic solvents used in the reaction include alcohols, ethers, ketones, amides, esters, and hydrocarbon compounds, with diethylene glycol ethyl methyl ether and propylene glycol monomethyl ether acetate being more preferred. The reaction temperature is preferably set to 30°C to 120°C, and the reaction time is preferably set to 1 hour to 36 hours. The amount of organic solvent used (a) is preferably set to 0.1% to 60% by mass relative to the total amount of monomers used in the reaction (b) and the total amount of the reaction solution (a+b).

[0076] For addition polymers (P), the weight-average molecular weight (Mw) of polystyrene, as determined by GPC, is preferably 250 to 500,000, more preferably 500 to 100,000.

[0077] Furthermore, the method for manufacturing addition polymers (P) is not limited to those described above. For example, it can also be obtained by polymerizing a monomer containing an unsaturated monomer (m-1) with an epoxy group in the presence of a polymerization initiator, and then reacting the polymer of the obtained monomer with a specific carboxylic acid.

[0078] When polymer (P) has a partial structure represented by formula (1) in its main chain, from the viewpoint of ease of incorporation of the partial structure represented by formula (1), polymer (P) is preferably selected from at least one of the group consisting of polyamide, polyimide, and polyamide ester. When polymer (P) has a partial structure represented by formula (1) in its side chain, polymer (P) is preferably selected from at least one of the group consisting of polyamide, polyimide, polyamide ester, polyorganosiloxane, and addition polymer.

[0079] <Other Ingredients> The liquid crystal alignment agent of the present invention may further contain components different from polymer (P) (hereinafter also referred to as "other components"). Examples of other components include polymers (hereinafter also referred to as "polymer (Q)") that do not have the partial structure represented by the formula (1), crosslinking agents, and solvents.

[0080] (Aggregate (Q)) The polymer (Q) can be used to improve the solubility of the polymer components, or the alignment and electrical properties of the liquid crystal alignment film. Examples of polymers (Q) with polyamide, polyamide ester, polyimide, polyorganosiloxane, polyester, polyamide, polybenzoxazole precursor, polybenzoxazole, cellulose derivatives, polyacetal, and addition polymers as the main framework can be included. In the preparation of liquid crystal alignment agents, polymers (Q) can be used alone or in combination of two or more.

[0081] In terms of improving the liquid crystal alignment and electrical properties of the obtained liquid crystal element, polymer (Q) is preferably at least one selected from the group consisting of polyacrylic acid, polyacrylic ester, polyimide, and addition polymers. Specific examples of polyacrylic acid, polyacrylic ester, and polyimide in polymer (Q) include polymers obtained by reacting the other acid dianhydrides with other diamines. Addition polymers in polymer (Q) are preferably polymers obtained using one or more monomers having (meth)acrylic, vinyl, vinylphenyl, or maleimide groups, and more preferably at least one selected from the group consisting of poly(meth)acrylate, maleimide polymers, and styrene-maleimide copolymers.

[0082] When the liquid crystal alignment agent contains polymer (Q), the proportion of polymer (Q) in the liquid crystal alignment agent is preferably set to 20 parts by mass to 99.9% by mass, and more preferably 30 parts by mass to 99% by mass, relative to 100 parts by mass of the total mass of polymer (P) and polymer (Q).

[0083] Furthermore, when the liquid crystal alignment agent contains polymer (Q), the content of polymer (P) in the liquid crystal alignment agent is preferably set to 0.5 parts by mass or more, more preferably 1% by mass or more, relative to 100 parts by mass of polymer (Q). Furthermore, the content of polymer (P) is preferably set to 150 parts by mass or less, more preferably 120 parts by mass or less, and even more preferably 100 parts by mass or less, relative to 100 parts by mass of polymer (Q).

[0084] (Cross-linking agent) The liquid crystal alignment agent of the present invention may contain a crosslinking agent. By incorporating a crosslinking agent into the liquid crystal alignment agent, the reliability under long-term irradiation with respect to backlight can be improved, which is even better.

[0085] The crosslinking agent is preferably a compound having functional groups that can react with functional groups (e.g., amino groups, carboxyl groups, epoxy groups, polymeric unsaturated groups, etc.) present in the polymer (P). Specifically, it is more preferably a compound having at least one selected from the group consisting of cyclic ether groups, carboxyl groups, cyclic carbonate groups, alcoholic hydroxyl groups, amino groups, protected amino groups, protected isocyanate groups, trialkoxysilyl groups, and polymeric unsaturated groups, and having a molecular weight of 1000 or less. The crosslinking agent preferably has two or more crosslinking groups, more preferably three or more, and more preferably three to eight.

[0086] When formulating a crosslinking agent, the content of the crosslinking agent in the liquid crystal alignment agent is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, relative to 100 parts by mass of the total polymer component in the liquid crystal alignment agent. Furthermore, from the viewpoint of suppressing performance degradation caused by excessive addition, the content of the crosslinking agent is preferably 40 parts by mass or less, and more preferably 30 parts by mass or less, relative to 100 parts by mass of the total polymer component in the liquid crystal alignment agent. Moreover, one type of crosslinking agent or a combination of two or more types can be used as the crosslinking agent.

[0087] (solvent) The liquid crystal alignment agent of the present invention is preferably prepared as a liquid composition formed by dispersing or dissolving the polymer (P) and, as needed, other components in a suitable solvent. The solvent used is preferably an organic solvent, such as: N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolium ketone, γ-butyrolactone, γ-butyrolactamine, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone (diacetone alcohol), ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, etc. Glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-isopropyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisoamyl ether, ethylene carbonate, propylene carbonate, etc. These can be used alone or in combination of two or more.

[0088] Other components, besides solvents, include, for example, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, and photosensitizers. The proportions of these components can be appropriately selected based on the specific compounds, without compromising the effectiveness of the invention.

[0089] The concentration of solid components in the liquid crystal alignment agent (the proportion of the total mass of components other than the solvent in the total mass of the liquid crystal alignment agent) can be appropriately selected considering factors such as viscosity and volatility, and is preferably in the range of 1% to 10% by mass. That is, the liquid crystal alignment agent is coated onto the substrate surface as described later, preferably by heating, thereby forming a coating that serves as a liquid crystal alignment film or a coating that forms a liquid crystal alignment film. At this point, if the solid component concentration is 1% by mass or more, the film thickness of the coating can be sufficiently ensured, making it easier to obtain a good liquid crystal alignment film, which is preferable from this perspective. Furthermore, if the solid component concentration is 10% by mass or less, the film thickness of the coating will not become excessive, resulting in a good liquid crystal alignment film, and the viscosity of the liquid crystal alignment agent can be appropriately ensured, leading to good coatability.

[0090] From the viewpoint of fully obtaining the effects of the present invention, the proportion of polymer components in the liquid crystal alignment agent is more preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 50 parts by mass or more, relative to the total 100 parts by mass of solid components (i.e., components other than solvents) in the liquid crystal alignment agent.

[0091] Liquid crystal alignment films and liquid crystal elements The liquid crystal alignment film of the present invention can be formed from the liquid crystal alignment agent prepared as described above. Furthermore, the liquid crystal element of the present invention includes a liquid crystal alignment film formed using the liquid crystal alignment agent described above. The operating mode of the liquid crystal in the liquid crystal element is not particularly limited, and can be applied to various modes such as twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA) (including vertical alignment-multi-domain vertical alignment (VA-MVA), vertical alignment-patterned vertical alignment (VA-PVA), etc.), in-plane switching (IPS), fringe field switching (FFS), and optically compensated bending (OCB), etc. The liquid crystal element can be manufactured, for example, by a method including steps 1 to 3 below. In step 1, the substrate used varies depending on the desired operating mode. Steps 2 and 3 share common operating modes.

[0092] (Step 1: Coating Formation) First, a liquid crystal alignment agent is coated onto a substrate, preferably by heating the coated surface, thereby forming a coating film on the substrate. Examples of substrates that can be used include: float glass, soda glass, etc.; and transparent substrates containing plastics such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly(alicyclic olefins). As a transparent conductive film disposed on one side of the substrate, a NESA film (a registered trademark of PPG Industries, Inc.) containing tin oxide (SnO₂) or an indium tin oxide (ITO) film containing indium oxide-tin oxide (In₂O₃-SnO₂) can be used. In the case of manufacturing TN, STN, or VA type liquid crystal elements, two substrates with patterned transparent conductive films are used. On the other hand, in the case of manufacturing IPS or FFS type liquid crystal elements, a substrate with electrodes containing a patterned comb-shaped transparent conductive film or metal film, and an opposing substrate without electrodes are used. As a metal film, for example, a film containing metals such as chromium can be used. The coating of the liquid crystal alignment agent on the substrate is preferably performed on the electrode forming surface using offset printing, spin coating, roller coating, or inkjet printing.

[0093] After applying the liquid crystal alignment agent, it is preferable to preheat (pre-baking) to prevent the applied liquid crystal alignment agent from sagging. The pre-baking temperature is preferably 30℃~150℃, and more preferably 40℃~120℃. The pre-baking time is preferably 0.25 minutes~10 minutes.

[0094] Subsequently, a calcination (post-baking) step is performed to further remove the solvent and, if necessary, to thermally amide the amide structure present in the polymer. From the viewpoint of suppressing degradation such as fading caused by high temperatures during the formation of the liquid crystal alignment film on the color filter, and from the viewpoint of reducing environmental impact, the calcination temperature (post-baking temperature) at this time is preferably 250°C or lower, more preferably 230°C or lower, and even more preferably 180°C or lower. Furthermore, from the viewpoint of suppressing the reduction in liquid crystal alignment or reliability due to the influence of residual solvent components in the film, the post-baking temperature is preferably 80°C or higher, and more preferably 120°C or higher. The post-baking time is preferably 5 minutes to 150 minutes. The film thickness thus formed is preferably 0.001 μm to 1 μm. After coating the liquid crystal alignment agent onto the substrate, the organic solvent is removed, thereby forming a liquid crystal alignment film, or a coating that becomes a liquid crystal alignment film.

[0095] (Step 2: Orientation Treatment) When manufacturing TN, STN, IPS, or FFS type liquid crystal elements, an alignment process (alignment treatment) is performed to impart liquid crystal alignment capability to the coating film formed in step 1. This imparts alignment capability to the liquid crystal molecules, creating a liquid crystal alignment film. Preferably, the alignment treatment involves rubbing the surface of the coating film formed on the substrate with cotton or similar material, or photoalignment treatment by irradiating the coating film with light to impart liquid crystal alignment capability. When manufacturing vertically aligned liquid crystal elements, the coating film formed in step 1 can be used directly as a liquid crystal alignment film; however, alignment treatment can also be performed on the coating film to further improve the liquid crystal alignment capability.

[0096] The photo-alignment process can be performed by methods such as: irradiating the coating after the post-baking step, irradiating the coating after the pre-baking step and before the post-baking step, or irradiating the coating during the heating process in at least one of the pre-baking and post-baking steps. In the photo-alignment process, the radiation used to irradiate the coating can be, for example, ultraviolet light or visible light with wavelengths from 150 nm to 800 nm. Ultraviolet light with wavelengths from 200 nm to 400 nm is more preferred. When the radiation is polarized, it can be linearly polarized or partially polarized. Furthermore, when using linearly polarized or partially polarized radiation, irradiation can be performed from a direction perpendicular to the substrate surface, from an inclined direction, or a combination of these. When irradiating unpolarized radiation, the irradiation direction is set to an inclined direction.

[0097] The light source used can be, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, or an excimer laser. The radiation dose is preferably 400 J / m² to 20,000 J / m², more preferably 1,000 J / m² to 5,000 J / m². To improve reactivity, the coating can be heated while being irradiated with light. Furthermore, the process may include contacting the light-irradiated organic film with water, a water-soluble organic solvent, or a mixture of water and a water-soluble organic solvent.

[0098] (Step 3: Construction of liquid crystal cells) Two substrates with liquid crystal alignment films formed as described above are prepared, and liquid crystal is disposed between the two substrates facing each other, thereby manufacturing a liquid crystal cell. Examples of methods for manufacturing a liquid crystal cell include: [1] arranging two substrates facing each other with liquid crystal alignment films facing each other and a gap (spacer) between them, bonding the peripheries of the two substrates together with a sealant, injecting liquid crystal to fill the cell gap defined by the substrate surface and the sealant, and then sealing the injection hole; [2] applying a sealant to a predetermined area on one of the substrates with the liquid crystal alignment film, then dropping liquid crystal at predetermined locations on the surface of the liquid crystal alignment film, bonding the other substrate with the liquid crystal alignment films facing each other, and allowing the liquid crystal to diffuse across the entire surface of the substrate (one-drop filling (ODF) method), etc. More preferably, the manufactured liquid crystal cell is further treated by heating it to a temperature at which the liquid crystal used achieves an isotropic phase, and then slowly cooling it to room temperature, thereby removing the flow alignment during liquid crystal filling.

[0099] As a sealant, for example, a hardener and epoxy resin containing alumina balls as spacers can be used. As spacers, photospacers, bead spacers, etc., can be used.

[0100] Examples of liquid crystals used include nematic liquid crystals and smectic liquid crystals, with nematic liquid crystals being more preferred. Examples of nematic liquid crystals include: Schiff base-based liquid crystals, azo-based liquid crystals, biphenyl-based liquid crystals, phenylcyclohexane-based liquid crystals, ester-based liquid crystals, terphenyl-based liquid crystals, biphenylcyclohexane-based liquid crystals, pyrimidine-based liquid crystals, dioxane-based liquid crystals, dicyclooctane-based liquid crystals, and cubane-based liquid crystals. Furthermore, cholesteric liquid crystals, chiral reagents, and ferroelectric liquid crystals can be added to these liquid crystals for further processing.

[0101] Next, a polarizing plate is attached to the outer surface of the liquid crystal cell as needed. Examples of polarizing plates include those formed by sandwiching a polarizing film called an "H-film" with a cellulose acetate protective film, or those containing an H-film itself, wherein the "H-film" is formed by absorbing iodine while extending and aligning polyvinyl alcohol. Thus, a liquid crystal element is obtained.

[0102] The liquid crystal element of this invention can be effectively applied to a variety of uses. Specifically, it can be used in various display devices such as clocks, portable game consoles, word processors, notebook computers, car navigation systems, camcorders, personal digital assistants (PDAs), digital cameras, mobile phones, smartphones, various monitors, LCD TVs, and message displays, or in dimming films. Furthermore, the liquid crystal element formed using the liquid crystal alignment agent of this invention can also be applied to optical films such as retardation films.

[0103] Liquid Crystal Display Devices One embodiment of the liquid crystal display device of the present invention includes a photoalignment film formed using the liquid crystal alignment agent described above as the liquid crystal alignment film. Hereinafter, the liquid crystal display device of the present invention will be described with reference to the accompanying drawings.

[0104] As shown in Figure 1, the liquid crystal display device 10 includes: a pair of substrates, including a first substrate 11 and a second substrate 12; and a liquid crystal layer 13 disposed between the first substrate 11 and the second substrate 12. The liquid crystal display device 10 is a thin film transistor (TFT) type liquid crystal display device. Furthermore, this invention can also be applied to other driving methods (e.g., passive matrix method, plasma address method, etc.).

[0105] The first substrate 11 is a TFT substrate in which pixel electrodes containing a transparent conductor such as indium tin oxide (ITO), TFTs as switching elements, scan lines, or signal lines are disposed on the surface of a transparent substrate 14 containing glass or resin on the side of the liquid crystal layer 13. The second substrate 12 is a color filter (CF) substrate in which a black matrix 17, a color filter 18, and a counter electrode 19 (also called a common electrode) containing a transparent conductor are disposed on the surface of a transparent substrate 16 containing glass or resin on the side of the liquid crystal layer 13.

[0106] A liquid crystal alignment film is formed on a pair of substrates 11 and 12, which aligns liquid crystal molecules in a predetermined orientation relative to the film surface. The liquid crystal alignment film is a vertical alignment film. The liquid crystal display device 10 includes a first alignment film 22 formed on the electrode arrangement surface of the first substrate 11 and a second alignment film 23 formed on the electrode arrangement surface of the second substrate 12 as liquid crystal alignment films.

[0107] The first substrate 11 and the second substrate 12 are arranged with the electrode mounting surfaces of the first substrate 11 and the second substrate 12 facing each other, separated by a spacer 24 and with a predetermined gap (cell spacing). Furthermore, in FIG1, columnar spacers are shown as spacers 24, but other spacers such as bead spacers may also be used. The pair of opposing substrates 11 and 12 are bonded together at their peripheries via a sealing material 25. A liquid crystal composition is filled into the space surrounded by the first substrate 11, the second substrate 12, and the sealing material 25. Thus, a liquid crystal layer 13 is formed between the first substrate 11 and the second substrate 12. The liquid crystal layer 13 is filled with liquid crystal having a negative dielectric anisotropy.

[0108] A polarizing plate (not shown) is disposed on the outer side of each of the first substrate 11 and the second substrate 12. A terminal area is provided on the outer edge of the first substrate 11. By connecting a driver integrated circuit (IC) or the like for driving the liquid crystal to the terminal area, the liquid crystal display device 10 is driven.

[0109] At least one of the first alignment film 22 and the second alignment film 23 is a photoalignment film. In this embodiment, at least the first alignment film 22 is a photoalignment film. Furthermore, in this specification, "photoalignment film" refers to a liquid crystal alignment film in which liquid crystal alignment capability is acquired by irradiating a coating formed using a polymer having photoalignment groups with polarized or unpolarized light. "Photoalignment groups" are functional groups that impart anisotropy to the film through photoisomerization, photodimerization, photodecomposition, or photorearrangement reactions caused by light irradiation.

[0110] The first alignment film 22 is segmented and exposed in a manner that differentiates the alignment orientation of liquid crystal molecules in each region by photoalignment processing. The first alignment film 22 is formed by repeatedly irradiating a coating film containing a polymer (P) having a partial structure represented by the formula (1) with polarized radiation using a light mask (e.g., a polarizer). On the other hand, the second alignment film 23 is not segmented and exposed. Regarding the second alignment film 23, in this embodiment, a coating film formed directly using the same liquid crystal alignment agent as the first alignment film 22 is used without irradiation. As a result, the pretilt angle defined by the first alignment film 22 is different from the pretilt angle defined by the second alignment film 23. Specifically, the pretilt angle defined by the first alignment film 22 is set to be less than 90 degrees, and the pretilt angle defined by the second alignment film 23 is set to be substantially 90 degrees.

[0111] Alternatively, instead of irradiating the organic film formed by the liquid crystal alignment agent to make the pretilt angle of the second alignment film 23 substantially 90 degrees during its formation, the entire surface of the organic film formed by the liquid crystal alignment agent can be exposed to unpolarized light from the substrate normal direction without using a light shield, thus making the pretilt angle of the second alignment film 23 substantially 90 degrees. In this case, the exposure of the second substrate 12 can be either parallel light or diffused light. The "pretilt angle" refers to the angle between the surface of the alignment film and the long axis direction of the liquid crystal molecules near the alignment film when the voltage is off.

[0112] The liquid crystal display device 10 has a plurality of pixels 30, which are arranged in a matrix in the display area of ​​the liquid crystal display device 10. Each pixel 30 is oriented and divided into multiple regions with different alignment orientations of liquid crystal molecules. This compensates for the viewing angle characteristics of the liquid crystal display device 10.

[0113] Furthermore, in this specification, the term "pixel" refers to the smallest unit that describes the shades (grayscale) of each color in a display. For example, in a color filter-based display device, it is equivalent to the unit describing the individual grayscale levels of red (R), green (G), and blue (B). Therefore, when referred to as "pixel," it refers to each individual R pixel, G pixel, and B pixel, rather than a combination of R pixels, G pixels, and B pixels (image points). That is, in the case of a color liquid crystal display device, one pixel corresponds to any color of the color filter.

[0114] Figures 2(a) to 2(c) show an example of the alignment pattern of pixel 30. Furthermore, in Figure 2(a), the cone represents the liquid crystal molecule 35, the apex side of the cone represents the first substrate 11 side, and the base side of the cone represents the second substrate 12 side. Figure 2(a) is a view of the liquid crystal display device 10 taken from the second substrate 12 side.

[0115] As an example, as shown in FIG2(a), four alignment regions with different alignment orientations of liquid crystal molecules 35 are formed in each pixel 30. The four alignment regions (first region 31, second region 32, third region 33, and fourth region 34) are arranged in a pixel along the long side direction of the pixel 30 (Y direction in FIG2(a) to FIG2(c)). Among the alignment orientations of liquid crystal molecules 35 in the first region 31 to the fourth region 34, the difference between any two alignment orientations is approximately equal to an integer multiple of 90 degrees. Furthermore, in this specification, "alignment orientation of liquid crystal molecules" refers to the alignment orientation of liquid crystal molecules near the center in the layer and thickness direction of the liquid crystal layer 13 when a voltage is applied to the liquid crystal display device 10, unless otherwise specified.

[0116] Specifically, when the short side direction of pixel 30 (the X direction in Figures 2(a) to 2(c)) is set to 0 degrees, the alignment orientation of the liquid crystal molecules 35 is substantially 45 degrees in the first domain 31, substantially 135 degrees in the second domain 32, substantially 225 degrees in the third domain 33, and substantially 315 degrees in the fourth domain 34. As shown in Figure 2(a), the four domains 31 to 34 are arranged within a pixel in the order of fourth domain 34, second domain 32, third domain 33, and first domain 31 along the long side direction of pixel 30. Signal lines 36 are arranged at positions where the light-transmitting area (hereinafter also referred to as the "pixel area") of each pixel 30 is divided into two along the long side direction of pixel 30. In the two domains (fourth domain 34 and second domain 32) that form one of the pixel regions divided by the signal line 36, and in the two domains (third domain 33 and first domain 31) that form the other pixel region, the alignment orientations of the liquid crystal molecules 35 in each domain differ by 180 degrees from each other (see Figure 2(a)).

[0117] Furthermore, in this specification, the terms "substantially 45 degrees," "substantially 135 degrees," "substantially 225 degrees," and "substantially 315 degrees" refer to the ranges of 45 degrees ± 0.5 degrees, 135 degrees ± 0.5 degrees, 225 degrees ± 0.5 degrees, and 315 degrees ± 0.5 degrees, respectively. More preferably, each angle is β degrees ± 0.2 degrees, and even more preferably β degrees ± 0.1 degrees (where β is 45, 135, 225, or 315).

[0118] Figures 2(b) and 2(c) schematically illustrate the orientation (tilt orientation) of the long axis direction of the liquid crystal molecules on the surface of the alignment film in each substrate of a pixel 30 projected onto the substrate when the voltage is off. In Figures 2(a) to 2(c), Figure 2(b) represents the first substrate 11, and Figure 2(c) represents the second substrate 12. Arrow 37 in Figures 2(a) to 2(c) indicates the tilt orientation. In the liquid crystal display device 10, by irradiating the first alignment film 22 of the first alignment film 22 and the second alignment film 23 with polarized radiation in a direction corresponding to the alignment orientation of the liquid crystal molecules 35, the desired pretilt angle characteristics are imparted to each region 31 to 34. On the other hand, polarized ultraviolet radiation is not irradiated onto the second alignment film 23. By means of this exposure process, in each alignment region of the first domain 31 to the fourth domain 34, the pretilt angle θ1 specified by the first alignment film 22 is set to be less than 90 degrees, and the pretilt angle θ2 specified by the second alignment film 23 is set to be substantially 90 degrees.

[0119] The pretilt angle θ1 only needs to be smaller than the pretilt angle θ2 specified by the second alignment film 23. From the viewpoint of suppressing the response delay of the liquid crystal molecules 35, the pretilt angle θ1 is preferably 89.0 degrees or less, and more preferably 88.5 degrees or less. In addition, from the viewpoint of suppressing the decrease in contrast of the liquid crystal display device 10, the pretilt angle θ1 is preferably 81.0 degrees or more, and more preferably 83.0 degrees or more. Furthermore, in this specification, "substantially 90 degrees" means a range of 90 degrees ± 0.5 degrees.

[0120] As shown in Figure 2(b), the tilt orientation of the first substrate 11 side is different in each of the first domain 31 to the fourth domain 34, and the difference between the tilt orientations in any two domains is approximately an integer multiple of 90 degrees. Specifically, regarding the tilt orientation in each domain, when the short side direction (X direction) of pixel 30 is set to 0 degrees, it is substantially 45 degrees in the first domain 31, substantially 135 degrees in the second domain 32, substantially 225 degrees in the third domain 33, and substantially 315 degrees in the fourth domain 34.

[0121] Furthermore, as shown in Figures 3(a) and 3(b), the plurality of pixels 30 of the liquid crystal display device 10 are arranged in such a way that the alignment orientations of adjacent domains in the short-side direction (X direction) of the pixel 30 are identical. In addition, in Figures 3(a) and 3(b), arrow 41 indicates the exposure orientation of the polarizing radiation on the coating formed using the liquid crystal alignment agent. Symbol 44 indicates the region corresponding to the fourth domain 34 of each pixel.

[0122] By using a polymer (P) having a partial structure represented by the formula (1) to form the photoalignment film in the liquid crystal display device 10, a liquid crystal display device with high transmittance and high reliability that does not easily decrease liquid crystal alignment even after long-term backlight irradiation can be obtained.

[0123] The liquid crystal display device 10 can be effectively applied to a variety of uses. For example, the liquid crystal display device 10 can be used as a clock, portable game console, word processor, notebook computer, car navigation system, camera, personal digital assistant, digital camera, mobile phone, smartphone, various monitors, LCD TV, message display and other display devices.

[0124] [Example] The present invention will be described in more detail below by way of examples, but the present invention is not limited to these examples.

[0125] In the following examples and comparative examples, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer, the amide content of the polyimide, and the epoxy equivalent were determined by the following methods.

[0126] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polymer] Mw and Mn are polystyrene conversion values ​​determined by gel permeation chromatography under the following conditions. Tube column: Manufactured by Tosoh (stock), TSKgelGRCXLII Solvents: tetrahydrofuran (for polyorganosiloxanes and addition polymers), or lithium bromide and phosphoric acid-containing N,N-dimethylformamide solution (for polyamide esters). Temperature: 40℃ Pressure: 68 kgf / cm²

[0127] [Acetimation rate] A solution containing polyimide was added to pure water. The resulting precipitate was thoroughly dried under reduced pressure at room temperature and then dissolved in deuterated dimethyl silane. Using tetramethylsilane as a reference, 1H-NMR spectra were measured at room temperature. The amide concentration was determined using the following formula (E-1) based on the obtained 1H-NMR spectrum. Acrylimization rate (%) = (1 - A1 / A2 × α) × 100 … (E-1) (In equation (E-1), A1 is the peak area of ​​protons originating from NH groups that appear near a chemical shift of 10 ppm, A2 is the peak area of ​​other protons, and α is the proportion of other protons relative to the number of 1 proton of NH groups in the precursor of the polymer (polyacrylic acid).)

[0128] [Epoxy Equivalent] The epoxy equivalent was determined using the hydrochloric acid-methyl ethyl ketone method as described in Japanese Industrial Standards (JIS) C 2105.

[0129] The structural formulas of the compounds used in this embodiment are shown below. Furthermore, for convenience, the "compound represented by formula (X)" will be simply referred to as "compound (X)".

[0130] (Tetracarboxylic acid derivative) [Chemistry 15]

[0131] (Diamine) [Chemistry 16]

[0132] (Carboxylic acid for modification) [Chemistry 17]

[0133] (Unsaturated monomers) [Chemistry 18] [Chemistry 19]

[0134] (additive) [Chemistry 20] [Chemistry 21]

[0135] 1. Synthesis of compounds [Synthesis Example 1-1] Compound (DA-1) was synthesized following the procedure described below. [Chemistry 22]

[0136] Synthesis of compound (DA-1-1) 16.5 g (100 mmol) of 4-nitrobenzaldehyde and 11.3 g (100 mmol) of cyanomalic acid were dissolved in 500 ml of pyridine. 25 ml of piperidine was added, and the mixture was reacted at 80 °C for 5 hours. After the reaction, the mixture was cooled to room temperature, and 300 ml of ethyl acetate was added, followed by 200 ml of hydrochloric acid. The mixture was separated into layers. After two separate layers using 300 ml of water, the solvent was removed by rotary evaporation to obtain a solid. The obtained solid was stirred under reflux with 100 ml of water and 5 g of sodium hydroxide for 3 hours. After stirring, the pH was adjusted to 4 using hydrochloric acid. The precipitated solid was filtered, washed with water, and dried to obtain 20.3 g of the intermediate compound (DA-1-1).

[0137] Synthesis of compound (DA-1-2) 2.61 g (10.0 mmol) of compound (DA-1-1) and 1.38 g (10.0 mmol) of 4-nitroaniline were dissolved in 50 mL of dichloromethane and cooled to 0 °C. Then, 1.86 g (12.0 mmol) of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimidine and 0.61 g (4.99 mmol) of 4-dimethylaminopyridine were added, and the mixture was allowed to react overnight at room temperature. The mixture was then subjected to a single separation using 50 mL of 1 equivalence hydrochloric acid and three separate separations using 50 mL of water. The organic layer was removed by solvent distillation using a rotary evaporator, yielding 3.27 g of compound (DA-1-2).

[0138] Synthesis of compound (DA-1) In a mixture of 3.52 g (10.0 mmol) of compound (DA-1-2), 30 ml each of THF and water were added, along with 10 equivalents of tin chloride. The mixture was reacted at 60 °C for 2 hours. After the reaction, 50 ml of ethyl acetate was added for separation. This was followed by two more separations using 50 ml of water, and the organic layer was removed by solvent distillation using a rotary evaporator. The obtained solid was dissolved in 50 ml of THF, with 30 ml of ethanol and 10 ml of water added. The solvent was slowly removed by distillation using a rotary evaporator, and the precipitated solid was filtered and dried to obtain 2.48 g of compound (DA-1).

[0139] [Synthesis Example 1-2] The compound (DA-3) was synthesized according to the following procedure. [Chemistry 23]

[0140] Synthesis of compound (DA-3-1) 200 ml of a dehydrated THF solution containing 30.2 g (120 mmol) of triethyl phosphonoacetate was added dropwise to 4.8 g (120 mmol) of sodium hydride, and the mixture was stirred at 0 °C for 2 hours. Then, 100 ml of a THF solution containing 21.9 g (100 mmol) of 4'-nitro-2,2,2-trifluoroacetophenone was added dropwise, and the mixture was stirred at room temperature for 1 hour, followed by reflux for 2 hours. After the reaction was complete, 300 ml of ethyl acetate was added, and the mixture was separated twice using saturated NH₄Cl solution and three times using water. The organic layer was removed by solvent distillation using a rotary evaporator, and then stirred under reflux for 3 hours with 300 ml of water and 10 g of sodium hydroxide. After stirring, the mixture was prepared to pH 4 using hydrochloric acid, and the precipitated solid was filtered off, washed with water, and dried to obtain 17.7 g of the intermediate compound (DA-3-1). Subsequently, compound (DA-3) was synthesized using the same method as compounds (DA-1-2) and (DA-1).

[0141] [Synthesis Example 1-3] The following procedure was followed to synthesize compound (DA-4). [Chemistry 24]

[0142] Synthesis of compound (DA-4-2) 2.51 g (10.0 mmol) of compound (DA-4-1) was reacted with 3.85 g (50.0 mmol) of ammonium acetate and 4.65 g (50.0 mmol) of aniline in 100 ml of ethanol, and the mixture was refluxed for 3 hours. After the reaction, the solvent was removed by rotary evaporation, and the mixture was dissolved in 50 ml of ethyl acetate and 50 ml of THF. The mixture was separated three times using hydrochloric acid of 1 stoichiometric concentration and three times using water. After removing the organic layer by solvent distillation, the mixture was stirred under reflux for 3 hours with 100 ml of water and 3 g of sodium hydroxide. After stirring, the pH was adjusted to 4 using hydrochloric acid, the precipitated solid was filtered off, washed with water, and dried to obtain 2.76 g of compound (DA-4-2) as an intermediate. Subsequently, compound (DA-4) was synthesized using the same method as compounds (DA-1-2) and (DA-1).

[0143] [Synthesis Example 1-4] Compound (M-1) was synthesized following the procedure described below. [Chemistry 25]

[0144] Synthesis of compound (M-1-2) Compound (M-1-1) 31.0 g (100 mmol), 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) 76.0 g (500 mmol), Pd(PPh 3) 2Cl 287.8 mg (2.50 mmol), and 1,4-bis(diphenylphosphine)butane 2.130 g (10.0 mmol) were dissolved in 200 ml of dimethyl sulfoxide (DMSO) under nitrogen atmosphere. Then, 7.01 g (100 mmol) of propynic acid was added, and the reaction was carried out at 50 °C for 5 hours. The reaction mixture was then injected into 200 ml of ethyl acetate, and separated twice using 200 ml of saturated sodium bicarbonate solution, twice using 200 ml of 1 equivalence hydrochloric acid, and three times using 200 ml of water. The organic layer was removed by solvent distillation under reduced pressure, thereby obtaining 21.7 g of compound (M-1-2).

[0145] Synthesis of compound (M-1-3) 3.00 g (10.1 mmol) of compound (M-1-2) was dissolved in 100 ml of dichloromethane and cooled to 0°C in an ice bath. Then, 9 g of hydrobromic acid (47.0%-49.0%) was added, and the reaction was allowed to proceed for 5 hours. The reaction mixture was slowly injected into a saturated sodium hydroxide aqueous solution for separation. Subsequently, two separations were performed using 50 ml of 1-equivalent hydrochloric acid and 100 ml of water. The organic layer was removed by solvent distillation under reduced pressure. The obtained solid was purified by column chromatography to obtain 1.68 g of compound (M-1-3).

[0146] Synthesis of compound (M-1) 1.13 g (3.00 mmol) of compound (M-1-3) was mixed with 10 ml of thionyl chloride and a catalyst amount of dimethylformamide (DMF) and reacted at 60 °C for 2 hours. After the reaction, the thionyl chloride was removed by vacuum distillation. The obtained solid was dissolved in 20 ml of dehydrated THF to prepare solution A. Separating solution A from solution A, 0.391 g (3.00 mmol) of 2-hydroxyethyl methacrylate and 0.500 g of triethylamine were dissolved in 10 ml of dehydrated THF and cooled to 0 °C in an ice bath. Solution A was added dropwise to the solution, and the mixture was reacted overnight at room temperature. After the reaction, the reaction solution was separated twice with 1 stoichiometric amount of hydrochloric acid and three times with water. The organic layer was removed by vacuum distillation. The obtained viscous body was purified by column chromatography to obtain 1.03 g of compound (M-1).

[0147] [Synthesis Example 1-5] Compound (M-2) was synthesized following the procedure described below. [Chemistry 26]

[0148] Synthesis of compound (M-2-2) Except for changing the raw materials, compound (M-2-2) was synthesized using the same method as compound (DA-3-1).

[0149] Synthesis of compound (M-2) 3.70 g (10.0 mmol) of compound (M-2-2) was mixed with 20 ml of thionyl chloride and a catalyst amount of DMF, and the mixture was reacted at 60 °C for 2 hours. After the reaction, the thionyl chloride was removed by vacuum distillation. The obtained solid was dissolved in 50 ml of dehydrated THF to prepare solution A. Meanwhile, 1.90 g (10.0 mmol) of 4-hydroxyphenylmaleimide and 1.20 g of triethylamine were dissolved in 50 ml of dehydrated THF and cooled to 0°C in an ice bath. Solution A was added dropwise, and the mixture was reacted overnight at room temperature. After the reaction, the reaction mixture was separated twice with 1 stoichiometric amount of hydrochloric acid and three times with water, and the organic layer was removed by vacuum distillation. The obtained solid was then dissolved in 50 ml of THF, and 30 ml of ethanol and 10 ml of water were added. The solvent was slowly removed by distillation using a rotary evaporator, and the precipitated solid was filtered and dried to obtain 3.31 g of compound (M-2).

[0150] [Synthesis Example 1-6] Compound (M-3) was synthesized following the procedure described below. [Chemistry 27]

[0151] Synthesis of compound (M-3-2) The methyl ester of compound (M-3-2) was synthesized using the same method as described in the Journal of the American Chemical Society (J. Am. Chem. Soc.) 2001, 123, 40, 9918-9919. Then, compound (M-3-2) was hydrolyzed using the same method as compound (DA-1-1). Subsequently, the same method as compound (M-2) was used for further synthesis.

[0152] [Synthetic Examples 1-7 and 1-8] Except for replacing the raw materials, compounds (M-4) and (M-5) were synthesized using the same method as compound (M-2). [Chemistry 28] [Chemistry 29]

[0153] [Synthesis Example 1-9] Compound (M-6) was synthesized following the procedure described below. [Chemistry 30]

[0154] Synthesis of compound (M-6-1) 15.46 g (50.0 mmol) of compound (M-1-1), 16.0 ml (150.0 mmol) of methyl methacrylate, 1.52 g (5.00 mmol) of phosphorus (o-tolyl)3 (P(o-tolyl)3), 26.1 ml (150 mmol) of iPr2NEt, 561 mg (2.50 mmol) of palladium acetate, and 250 ml of DMF were added. The mixture was completely purged with nitrogen, heated to 100 °C, and reacted for 6 hours. After confirming the disappearance of the starting material by liquid chromatography (LC), the mixture was cooled to room temperature. 200 ml of ethyl acetate was added after cooling, and the mixture was stirred briefly at room temperature. The precipitate was filtered off. 200 ml of hexane was added to the filtrate, and the mixture was washed twice with 100 ml of 1 N HCl, twice with 100 ml of distilled water, and once with 100 ml of saturated saline solution. The organic layer was dried using anhydrous sodium sulfate, and the solvent was removed by vacuum distillation using a rotary evaporator and oil pump. The obtained solid was then mixed with 300 ml of water and 5 g of sodium hydroxide and stirred under reflux for 3 hours. After stirring, the pH was adjusted to 4 using hydrochloric acid, the precipitated solid was filtered off, washed with water, and dried to obtain 17.2 g of the intermediate compound (DA-6-2). Subsequently, compound (M-6) was synthesized using the same method as compound (M-2).

[0155] [Synthesis Example 1-10] Except for replacing the raw materials, compound (M-7) was synthesized using the same method as compound (M-6). [Chemistry 31]

[0156] 2. Synthesis of polymers Synthesis of Polyamides [Synthesis example 2-1] 50 moles of 2,3,5-tricarboxycyclopentylacetic dianhydride (compound (T-1)), 50 moles of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 70 moles of compound (DA-1) and 30 moles of compound (DA-2) were dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at 40°C for 3 hours to obtain a solution containing 10% by mass of polymer (P-1).

[0157] [Synthetic Examples 2-4, 2-11, 2-12, 2-13, Comparative Synthetic Example 3, Comparative Synthetic Example 4] Except for changing the types and amounts of the tetracarboxylic acid derivatives and diamines used as described in Table 1 below, the same operation as in Synthesis Example 2-1 was performed to obtain solutions containing polymers (P-10), (PAA-S), (PAA-1), (PAA-2), (P-13), and (P-14), respectively. Furthermore, in Table 1, the values ​​for the tetracarboxylic acid derivatives indicate the percentage (in moles) of each compound used in the synthesis of the polymers relative to the total amount of the tetracarboxylic acid derivatives. The values ​​for the diamines indicate the percentage (in moles) of each compound used in the synthesis of the polymers relative to the total amount of the diamines.

[0158] Synthesis of Polyimide [Synthesis example 2-2] 100 mol of 2,3,5-tricarboxycyclopentylacetic dianhydride (compound (T-1)), 20 mol of compound (DA-2), and 80 mol of compound (DA-3) were dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at 40°C for 3 hours to obtain a solution containing 10% by mass of polyacrylic acid. One mol each of pyridine and acetic anhydride, relative to 1 mol of tetracarboxylic dianhydride used in the polymerization, were added to the obtained polyacrylic acid solution, and a dehydration and ring-closure reaction was carried out at 100°C for 8 hours. The reaction mixture was then injected into a large amount of excess methanol to precipitate the reaction products. The recovered precipitate was washed with methanol and dried under reduced pressure at 40°C for 15 hours to obtain polymer (P-2). The acetylation rate of the obtained polymer (P-2) was 68%.

[0159] Synthesis of Polyamides [Synthesis example 2-3] In a 200 mL three-necked flask including a nitrogen inlet tube, a reflux condenser, and a thermometer, 22.42 g of the compound represented by formula (TA-3), 100 mL of tetrahydrofuran, and 0.79 g of pyridine were placed and stirred under a nitrogen stream to suspend the mixture. 15.14 g of β-methylallyl alcohol was added to this suspension, and the mixture was stirred at room temperature for 2 hours. The reaction was then carried out at 60 °C for 8 hours to obtain a colorless, transparent solution. This reaction solution was concentrated under reduced pressure at 60 °C and then dried under vacuum to obtain 36.84 g of a mixture of the compounds represented by formula (DE-1a) and (DE-1b) (hereinafter referred to as "mixture (DE-1a / b)"). [Chemistry 32]

[0160] Subsequently, 18.42 g of the mixture (DE-1a / b) and 100 mL of toluene were placed in a 100 mL round-bottom flask including a nitrogen inlet tube and a reflux cooling tube, and stirred at 80 °C for 30 minutes. Then, the mixture was cooled to room temperature while stirring, and then stirred again at room temperature for 30 minutes. The resulting suspension was filtered and washed twice with 5 mL of toluene. The obtained solid was dried under vacuum at 60 °C to obtain 15.47 g of compound (DE-1a) as a white powder (yield 84%).

[0161] In a 500 mL three-necked flask including a nitrogen inlet tube, a reflux condenser, and a thermometer, 14.74 g of compound (DE-1a), 80 mL of heptane, and 0.032 g of pyridine were placed and stirred at 75 °C under a nitrogen flow. 14.28 g of thionyl chloride was slowly added dropwise over 20 minutes, and foaming was observed during the reaction. After the addition was complete, the reaction was carried out at 75 °C for 2 hours to obtain a colorless and transparent solution. The reaction solution was concentrated under reduced pressure at 60 °C to remove excess thionyl chloride by distillation. 80 mL of heptane was added to the obtained liquid, and the mixture was stirred at room temperature. The precipitated insoluble components were removed by filtration. The filtrate was concentrated under reduced pressure at 60 °C and then dried under high vacuum at 60 °C for 4 hours to obtain 15.89 g (98% yield) of the compound represented by the following formula (DE-1a) as a colorless and transparent liquid. [Chemistry 33]

[0162] In a 50 ml three-necked flask containing a nitrogen inlet tube and a thermometer, 100 moles of compound (T-3), 70 moles of compound (DA-2), 30 moles of compound (DA-4), 57 g of NMP, and 24 g of triethylamine were placed. The mixture was cooled to approximately 10 °C, and 83 g of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM) was added as a triazine dehydrating condensing agent. The reaction was carried out under a nitrogen atmosphere at room temperature for 24 hours. The resulting polymerization solution was diluted with NMP and slowly injected into methanol while stirring to allow it to solidify. The precipitated solid was recovered and washed twice with stirring in methanol, then vacuum dried at 60°C to obtain a white polyamide powder (hereinafter referred to as "polymer (P-3)"). The polymer has a number-average molecular weight Mn of 14,000 and a molecular weight distribution Mw / Mn of 2.8.

[0163] [Table 1] Synthesis example polymer name Tetracarboxylic acid derivatives diamine T-1 T-2 T-3 DA-1 DA-2 DA-3 DA-4 DA-5 DA-6 DA-7 DA-8 DA-9 Synthesis example 2-1 P-1 50 50 70 30 Synthesis example 2-2 P-2 100 20 80 Synthesis example 2-3 P-3 100 70 30 Synthesis example 2-4 P-10 100 20 80 Synthesis example 2-11 PAA-S 100 100 Synthesis example 2-12 PAA-1 100 100 Synthesis example 2-13 PAA-2 100 80 20 Comparative Synthesis Example 3 P-13 70 30 20 80 Comparative Synthesis Example 4 P-14 100 50 50

[0164] Synthesis of Polyorganosiloxanes [Synthesis example 2-5] In a reaction vessel including a stirrer, thermometer, dropping funnel, and reflux cooling tube, 100.0 g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 500 g of methyl isobutyl ketone, and 10.0 g of triethylamine were mixed at room temperature. Then, 100 g of pure water was slowly added dropwise, and the mixture was stirred at 80°C for 6 hours. The organic layer was then removed and washed with a 0.2% (w / w) ammonium nitrate aqueous solution until the washing water was neutral. The mixture was then concentrated to obtain an epoxy-containing polyorganosiloxane (EPS-1) as a viscous, transparent liquid. The Mw of the epoxy-containing polyorganosiloxane (EPS-1) was 2,200, and the epoxy equivalent was 186 g / mole. Subsequently, 8.0 g of the epoxy-containing polyorganosiloxane (EPS-1) obtained above, 26 g of methyl isobutyl ketone, 15.3 g of compound (CA-1), and 0.10 g of "UCAT 18X" (a quaternary amine salt manufactured by San-Apro) were added to a 100 mL three-necked flask, and the reaction was carried out under stirring at 80 °C for 12 hours. After the reaction was completed, the reaction mixture was added to methanol, the precipitate was recovered, dissolved in ethyl acetate to prepare a solution, the solution was washed three times with water, and the solvent was removed by distillation, thereby obtaining 23.2 g of polymer (P-4) as a white powder. The weight average molecular weight (Mw) of the polymer (P-4) was 14,100.

[0165] Synthesis of Addition Polymers [Synthesis example 2-6] Under nitrogen atmosphere, 9.0 g of compound (M-1), 3.0 g of compound (M-9), and 1.8 g of compound (M-10) as monomers were added to a 100 mL two-necked flask; 0.70 g of 2,2'-azobis(2,4-dimethylpentanilonitrile) as a free radical polymerization initiator; 0.20 g of 2,4-diphenyl-4-methyl-1-pentene as a chain transfer agent; and 50 mL of N-methyl-2-pyrrolidone (NMP) as a solvent. Polymerization was carried out at 70 °C for 6 hours. After reprecipitation in methanol, the precipitate was filtered and dried under vacuum at room temperature for 8 hours to obtain the target polymer (P-5). The weight-average molecular weight (Mw) determined by GPC and converted to polystyrene was 42,000, and the molecular weight distribution (Mw / Mn) was 2.1.

[0166] [Synthesis Examples 2-7 to 2-10, Comparative Synthesis Example 1, Comparative Synthesis Example 2, Comparative Synthesis Example 5] Except for changing the types and amounts of polymerizing monomers used as described in Table 2 below, the same operations as in Synthesis Examples 2-6 were performed to obtain polymers (P-6) to (P-9), (P-11), (P-12), and (P-15). Furthermore, in Table 2, the values ​​for polymerizing monomers represent the proportion (in moles) of each compound used in the synthesis of the polymer relative to the total amount of polymerizing monomers.

[0167] [Table 2] Synthesis example polymer name unsaturated monomers M-1 M-2 M-3 M-4 M-5 M-6 M-7 M-8 M-9 M-10 M-11 M-12 M-13 Synthesis example 2-6 P-5 30 35 35 Synthesis example 2-7 P-6 10 45 35 10 Synthesis example 2-8 P-7 25 37.5 12.5 25 Synthesis example 2-9 P-8 20 10 40 30 Synthesis example 2-10 P-9 5 47.5 42.5 5 Comparative synthesis example 1 P-11 10 45 35 10 Comparative Synthesis Example 2 P-12 30 35 5 30 Comparative Synthesis Example 5 P-15 15 42.5 42.5

[0168] 3. Manufacturing and evaluation of liquid crystal alignment agents and liquid crystal display devices. [Example 1] (1) Preparation of liquid crystal alignment agent In a container containing 5 parts by mass of polymer (P-1) obtained in Synthesis Example 2-1, 100 parts by mass of polymer (PAA-1) obtained in Synthesis Example 2-12, and 10 parts by mass of compound (ADD-1), NMP and butyl cellolsolve (BC) were added as solvents to prepare a solution with a solvent composition of NMP / BC = 50 / 50 (mass ratio) and a solid content concentration of 3.5% by mass. The solution was filtered using a filter with a pore size of 1 μm to prepare the liquid crystal alignment agent (AL-1).

[0169] (2) Manufacturing of optical FFS type liquid crystal display element Prepare a glass substrate having chromium-containing 2-system metal electrodes (electrode A and electrode B) patterned in a comb-like shape, and be capable of independently applying voltage to electrodes A and B. Pair the glass substrate with an opposing glass substrate without electrodes, and use a spin coater to coat the electrode-containing surface of the glass substrate and one surface of the opposing glass substrate with the liquid crystal alignment agent (AL-1) prepared above. Then, after pre-baking at 80°C for 1 minute, heat for 1 hour in a 200°C oven purged with nitrogen (post-baking) to form a coating with an average thickness of 0.08 μm. This process is repeated to obtain a pair (two pieces) of glass substrates with a coating on the transparent conductive film. The coating obtained above is then photo-aligned by irradiating the substrate with 2,000 J / cm² of polarized ultraviolet light containing a bright line at 313 nm from the substrate normal direction using an Hg-Xe lamp and a Glan-Taylorprism. This irradiation dose is measured using a photometer with a wavelength of 313 nm as a reference. Next, for one of the pair of substrates with the liquid crystal alignment film, an epoxy resin adhesive containing alumina spheres with a diameter of 3.5 μm is applied to the outer edge of the surface with the liquid crystal alignment film. The two substrates are then overlapped and pressed together with the liquid crystal alignment film surfaces facing each other, allowing the adhesive to harden. Subsequently, a liquid crystal composition (Merck, MLC-6221) is filled between the two substrates through the liquid crystal injection port, and the liquid crystal injection port is sealed using an acrylic photocurable adhesive to obtain a liquid crystal cell. Furthermore, two polarizing plates are attached to the outer surfaces of the substrate in the liquid crystal cell with their polarization directions orthogonal to each other.

[0170] (3) Evaluation of backlight reliability (BL reliability) The liquid crystal display element prepared above was placed on a high brightness backlight of 27,000 cd / m² for 500 hours, and the changes in characteristics before and after backlight irradiation were evaluated by the method described below (3A). (3A) Evaluate BL reliability based on lag rate of change The delay of the liquid crystal display element was measured using an Axoscan manufactured by Optoscience, and the rate of change of delay α before and after backlighting was calculated using the following formula (z-1). The smaller the rate of change α, the less likely the liquid crystal display element is to produce image retention even after long-term driving, and the better the reliability of the backlight. The case where the rate of change α is less than 0.5% is set as "best (◎)", the case where it is greater than 0.5% but less than 1% is set as "good (○)", the case where it is greater than 1% but less than 2% is set as "acceptable (△)", and the case where it is greater than 2% is set as "unacceptable (×)". α = Δθ / θ1 …(z-1) (In equation (z-1), Δθ represents the difference in delay before and after irradiation, and θ1 represents the delay before irradiation.) The result is rated as "good (○)" in this embodiment.

[0171] [Example 2, Example 3 and Comparative Example 3] Except for changing the formulation of the liquid crystal alignment agent as shown in Table 3, the liquid crystal alignment agent was prepared in the same manner as in Example 1. Furthermore, using the prepared liquid crystal alignment agent, an optical FFS type liquid crystal display element was manufactured in the same manner as in Example 1, and the same evaluation was performed as in Example 1. The results are shown in Table 3.

[0172] [Example 4] (1) Preparation of liquid crystal alignment agent In a container containing 50 parts by mass of polymer (P-4) obtained in Synthesis Examples 2-5, 100 parts by mass of polymer (PAA-1) obtained in Synthesis Examples 2-12, and 5 parts by mass of compound (ADD-4), NMP and BC were added as solvents to prepare a solution with a solvent composition of NMP / BC = 50 / 50 (mass ratio) and a solid content concentration of 3.5% by mass. The solution was filtered using a filter with a pore size of 1 μm to prepare the liquid crystal alignment agent (AL-4).

[0173] (2) Manufacturing of vertically oriented liquid crystal display elements (UV2A) The liquid crystal alignment agent (AL-4) prepared in (1) above was coated onto the transparent electrode surface of a glass substrate with a transparent electrode containing an ITO film using a rotator. After pre-baking at 80°C for 1 minute, it was formally calcined at 200°C for 40 minutes to form a coating with a thickness of 0.08 μm. Subsequently, the surface of the coating was irradiated with 200 J / m² of polarized ultraviolet light containing bright lines of 313 nm at room temperature from a direction tilted at 40° relative to the substrate normal using an Hg-Xe lamp and a Glan-Taylor prism. The same operation was repeated to fabricate a pair (two pieces) of substrates with liquid crystal alignment films. On the outer periphery of the surface of one of two substrates with a liquid crystal alignment film, an epoxy resin adhesive containing alumina spheres with a diameter of 3.5 μm is screen-printed onto the substrate. The substrates are then pressed together with their liquid crystal alignment film surfaces facing each other, so that the projection direction of the ultraviolet light axis irradiating each substrate onto the substrate surface is antiparallel. The adhesive is then heat-cured at 150°C for 1 hour. Next, a liquid crystal composition (Merck, MLC-6608) is filled into the gap between the substrates from the liquid crystal injection port, and the injection port is sealed with an epoxy adhesive to obtain a liquid crystal cell. Furthermore, to remove the flow alignment during liquid crystal injection, the liquid crystal cell is heated at 150°C and then slowly cooled to room temperature. Finally, polarizing plates are attached to the outer sides of the substrate in the liquid crystal cell, with their polarization directions orthogonal to each other and at a 45° angle to the projection direction of the ultraviolet light axis irradiated during the formation of the liquid crystal alignment film onto the substrate surface.

[0174] (3) Evaluation of BL reliability The liquid crystal display element prepared above was placed on a high brightness backlight of 27,000 cd / m² for 500 hours, and the changes in characteristics before and after backlight irradiation were evaluated by the method described below (3B). (3B) Evaluation of BL reliability based on tilt recovery The pretilt angle of the liquid crystal was measured using an Optipro instrument manufactured by Shintech Corporation. The pretilt angle before and after backlighting was compared to evaluate the reliability of the liquid crystal backlight (BL). A difference of less than 0.1 degrees between the pretilt angle and the backlighting was defined as "Best (◎)", greater than 0.1 degrees but less than 0.5 degrees as "Good (○)", greater than 0.5 degrees but less than 1.0 degrees as "Acceptable (△)", and greater than 1.0 degrees as "Unacceptable (×)". In this embodiment, the evaluation is "Acceptable (△)".

[0175] [Examples 5-10 and Comparative Examples 1, 2, 4, and 5] Except for changing the formulation of the liquid crystal alignment agent as shown in Table 3, the liquid crystal alignment agent was prepared in the same manner as in Example 4. Furthermore, using the prepared liquid crystal alignment agent, a vertically aligned liquid crystal display element was manufactured in the same manner as in Example 4, and the same evaluation was performed. The results are shown in Table 3.

[0176] [Table 3] Liquid crystal alignment agent composition Liquid crystal display element Polymer 1 Polymer 2 additive model BL reliability (alignment) type Quality type Quality type Quality Delayed rate of change Tilt recovery Example 1 P-1 5 PAA-1 100 ADD-1 10 Light FFS 〇 — Example 2 P-2 1 PAA-1 100 ADD-2 1 Light FFS 〇 — Example 3 P-3 10 PAA-1 100 ADD-3 5 Light FFS 〇 — Example 4 P-4 50 PAA-1 100 ADD-4 5 UV2A — △ Example 5 P-5 10 PAA-1 100 ADD-5 20 UV2A — △ Example 6 P-6 20 PAA-1 100 ADD-6 / ADD-7 5 / 5 UV2A — △ Example 7 P-7 30 PAA-1 100 UV2A — 〇 Example 8 P-8 20 PAA-2 100 ADD-8 30 UV2A — 〇 Example 9 P-9 100 PAA-2 100 PAA-S 20 UV2A — ◎ Example 10 P-10 50 PAA-1 100 UV2A — ◎ Comparative Example 1 P-11 10 PAA-1 100 UV2A — × Comparative Example 2 P-12 50 PAA-1 100 UV2A — × Comparative Example 3 P-13 25 PAA-1 100 Light FFS × — Comparative Example 4 P-14 1 PAA-1 100 UV2A — × Comparative Example 5 P-15 15 PAA-1 100 UV2A — ×

[0177] Based on the above results, it can be seen that in Examples 1 to 10, which prepared liquid crystal alignment agents containing polymer (P), the liquid crystal alignment was good even after prolonged exposure to backlight, and the BL reliability was excellent. In particular, in Example 7, Example 8, Example 9, Example 10 ...

[0178] In contrast, in Comparative Examples 1 to 5, which used liquid crystal alignment agents that did not contain polymer (P), the reliability of BL was evaluated as poor. Furthermore, in Comparative Example 5, which used a polymer (P-15) with an ester group (-COOMe) introduced at the β-position of the cinnamic acid ester structure, the reliability of BL was evaluated as unacceptable. The reason for this is presumably due to the decarboxylation of the ester group (-COOMe) during post-baking at high temperature.

[0179] [Example 11] (1) Preparation of liquid crystal alignment agent Using the polymer (P-9) obtained in Synthesis Examples 2-10, a liquid crystal alignment agent (AL-11) was prepared by the same composition and preparation method as in Example 9.

[0180] (2) Manufacturing and evaluation of liquid crystal display devices A liquid crystal display device corresponding to Figure 1 was manufactured. First, a TFT substrate having pixel electrodes and a CF substrate having opposing electrodes were prepared. As the pixel electrodes of the TFT substrate and the opposing electrodes of the CF substrate, full-surface electrodes without slits were used. The liquid crystal alignment agent (AL-11) prepared in (1) was coated on each electrode arrangement surface of the TFT substrate and the CF substrate by spin casting. After pre-baking at 80°C for 1 minute, it was baked at 230°C for 40 minutes to make the final film thickness 120 nm. Then, the coating (liquid crystal alignment film) formed on the TFT substrate was scanned and exposed. Regarding the scan exposure, according to Figures 2(a) to 2(c), four linearly polarized lights of 313 nm were applied with an intensity of 20 mJ / cm2 to form four domains with different alignment orientations of liquid crystal molecules within a pixel. On the other hand, the liquid crystal alignment film formed on the CF substrate using the liquid crystal alignment agent (AL-11) was not exposed.

[0181] Next, nematic liquid crystal with negative dielectric anisotropy was dropped onto the liquid crystal alignment film formation surface of the TFT substrate, and thermosetting epoxy resin was placed as a sealant at the outer edge of the CF substrate. Then, the alignment film surfaces of the TFT substrate and the CF substrate were bonded together with their inner surfaces facing each other. The epoxy resin was then cured by heating at 130°C for 1 hour to obtain a liquid crystal cell. The transmittance of the obtained liquid crystal cell was measured when driven with an alternating current (AC) of 6 V. The transmittance was evaluated using an Expert Liquid Crystal Display (LCD) manufactured by LinkGlobal 21 and calculated through simulation. As calculation conditions, the following liquid crystal properties were used: Δε=3, Ne=1.6, No=1.5, cell spacing: 3.2 μm, and pretilt angle: measured value (TFT substrate side: 88.0°, CF substrate side: 90.0°). The transmittance was evaluated based on the applied voltage of 6 V. A transmittance value less than 0.275 is rated as "Acceptable (△)", a value of 0.275 or higher but less than 0.280 is rated as "Good (○)", a value of 0.280 or higher but less than 0.285 is rated as "Excellent (◎)", and a value of 0.285 or higher is rated as "Best (◎◎)". Furthermore, similar to Example 4, the liquid crystal display device fabricated above was placed under a high-brightness backlight of 27,000 cd / m² for 500 hours, and the characteristic changes before and after backlight irradiation (BL reliability based on tilt recovery) were evaluated using the method described in (3B). The results are shown in Table 4.

[0182] [Comparative Example 6 and Reference Example 1] Except for the changes to the polymers used as shown in Table 4 below, liquid crystal alignment agents were prepared in the same manner as in Example 11. Furthermore, a liquid crystal display device was manufactured using the prepared liquid crystal alignment agents in the same manner as in Example 11, and the same evaluation was performed as in Example 11. The results are shown in Table 4.

[0183] [Table 4] Liquid crystal alignment agent LCD display device Transmission rate BL reliability (Tilt Restoration) Example 11 P-9 ◎◎ ◎ Comparative Example 6 P-11 〇 × Reference Example 1 P-12 ◎ 〇

[0184] As shown in Table 4, Example 11, which uses a liquid crystal alignment agent containing polymer (P), exhibits high transmittance and excellent BL reliability. In contrast, Comparative Example 6, which uses a liquid crystal alignment agent without polymer (P), shows worse transmittance and BL reliability than Example 11. Furthermore, in Reference Example 1, which uses a polymer containing a partial structure such that a substituent (methyl) is present at the α-position of the carbonyl carbon in Formula (1) instead of the β-position, the transmittance is rated as "◎", and the BL reliability based on tilt recovery is rated as "○". Based on these results, it is clear that using a liquid crystal alignment agent containing polymer (P) can improve the transmittance and BL reliability of the liquid crystal display device.

[0185] 10: Liquid crystal display device 11: First substrate / substrate 12: Second substrate / substrate 13: Liquid Crystal Layer 14:Transparent substrate 15: Pixel Electrode 16:Transparent substrate 17: Black Matrix 18: Color Filter 19: Opposite Electrodes 22: First alignment film 23: Second alignment film 24: Spacers 25: Sealing material 30 pixels 31: First Domain / Domain 32: Second domain / domain 33: Third Domain / Domain 34: Fourth Domain / Domain 35: Liquid crystal molecules 36: Wiring / Signal Cables 37, 41: Arrows 44: Corresponding region of the fourth domain X, Y: Direction

Claims

1. A liquid crystal alignment agent comprising a polymer (P) having a partial structure represented by the following formula (1), wherein in formula (1), Rβ is an alkyl group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms, a trialkylsilyl group, or -NR12R13, R12 and R13 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms; Rα is a hydrogen atom; X1 is an oxygen atom or -NR5-; R5 is a hydrogen atom or a monovalent organic group; R1 is a substituent, said substituent being an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a halogen atom, a hydroxyl group, a carboxyl group, an amino group, a cyano group, an alkylsilyl group, an alkoxysilyl group, or an ester group; n is an integer from 0 to 4; m is 0 or 1; "*" represents a bond.

2. The liquid crystal alignment agent as claimed in claim 1, wherein, The polymer (P) has a partial structure represented by formula (1) in its side chain.

3. The liquid crystal alignment agent as described in claim 2, wherein, The polymer (P) is at least one selected from the group consisting of polyamide, polyamide ester, polyimide, polyorganosiloxane and addition polymers.

4. The liquid crystal alignment agent as claimed in claim 1, wherein, The polymer (P) has a partial structure in the main chain represented by the formula (1).

5. The liquid crystal alignment agent as claimed in claim 4, wherein, The polymer (P) is at least one selected from the group consisting of polyamide, polyamide ester and polyimide.

6. The liquid crystal alignment agent as claimed in claim 1, wherein, The polymer (P) is at least one selected from the group consisting of polyamide, polyamide ester, polyimide, polyorganosiloxane and addition polymers.

7. The liquid crystal alignment agent as claimed in claim 1 further comprises a polymer (Q) that does not have the partial structure represented by formula (1).

8. The liquid crystal alignment agent as claimed in claim 7, wherein, The polymer (Q) is at least one selected from the group consisting of polyamide, polyamide ester, polyimide and addition polymers.

9. A method for manufacturing a liquid crystal alignment film, including: The step of forming a coating by coating a liquid crystal alignment agent as described in any one of claims 1 to 8 onto a substrate; The step of irradiating the coating with light.

10. A liquid crystal alignment film formed using a liquid crystal alignment agent as described in any one of claims 1 to 8.

11. A liquid crystal element comprising a liquid crystal alignment film as described in claim 10.

12. A liquid crystal display device, comprising a plurality of pixels, and further comprising: First substrate; The second substrate faces the first substrate; A liquid crystal layer is disposed between a first substrate and a second substrate and contains liquid crystal molecules; a first alignment film is formed on the first substrate and aligns the liquid crystal molecules; and a second alignment film is formed on the second substrate and aligns the liquid crystal molecules. At least one of the first alignment film and the second alignment film is a photoalignment film. Each pixel in the plurality of pixels has a first alignment region, a second alignment region, a third alignment region, and a fourth alignment region as regions where the alignment orientations of the liquid crystal molecules are different from each other. The first alignment region, the second alignment region, the third alignment region, and the fourth alignment region are arranged along the long side direction of the pixel. The difference between any two alignment orientations of the first alignment region, the second alignment region, the third alignment region, and the fourth alignment region is approximately equal to an integer multiple of 90 degrees. The plurality of pixels are arranged along the short side direction of the pixel such that the alignment orientations of adjacent alignment regions in the short side direction of the pixel are the same. In each alignment region of the first alignment region, the second alignment region, the third alignment region, and the fourth alignment region, one of the pretilt angles defined by the first alignment film and the second alignment film is less than 90 degrees, and the other is substantially 90 degrees. The photoalignment film is formed using a liquid crystal alignment agent as described in any one of claims 1 to 6.

13. A polymer having a partial structure represented by the following formula (1), wherein in formula (1), Rβ is an alkyl group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms, a trialkylsilyl group, or -NR12R13, R12 and R13 are each independently a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms; Rα is a hydrogen atom; X1 is an oxygen atom or -NR5-; R5 is a hydrogen atom or a monovalent organic group; R1 is a substituent, said substituent being an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a halogen atom, a hydroxyl group, a carboxyl group, an amino group, a cyano group, an alkylsilyl group, an alkoxysilyl group, or an ester group; n is an integer from 0 to 4; m is 0 or 1; "*" represents a bond.

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