Liquid crystal alignment agent, liquid crystal alignment film, and liquid crystal element

Abstract

To provide a liquid crystal alignment agent having a high coating property, capable of forming a liquid crystal alignment film that is excellent in seal adhesion and high in a refractive index, and of reducing an afterimage generated in a liquid crystal element.SOLUTION: The liquid crystal alignment agent includes a polymer component containing a polymer (A), and a compound (B). Content of the compound (B)is 50 mass % or less with respect to the polymer component 100 mass%. The polymer (A) is polyamic acid, for example, and includes 5 mol% or more of a structural unit (D) derived from diamine containing a specific nitrogen-containing group with respect to the total amount of a diamine compound unit composing the polymer (A). The compound (B)is a compound including at least one selected from a group consisting of a naphthalene ring structure, a fluorene ring structure, a carbazole ring structure, and a triazine ring structure, and a cross-linking group (however, excluding a compound having the triazine ring structure and a (meth) acryloyloxy group, containing only one (meth) acryloyloxy group).SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal element. [Background technology]

[0002] Liquid crystal elements generally comprise an electrode structure made of a transparent conductive film or the like, and a liquid crystal alignment film that has the function of aligning liquid crystal molecules in the liquid crystal layer in a certain direction. The liquid crystal alignment film is generally formed on the substrate by coating the substrate surface with a liquid crystal alignment agent, which is made by dissolving polymer components in an organic solvent, and preferably by heating it.

[0003] In recent years, with the rise of large-screen, high-definition LCD televisions and the increasing popularity of small display devices such as smartphones and tablet PCs, the demand for higher quality liquid crystal elements has increased even further. In light of these factors, various liquid crystal alignment agents have been proposed to improve the performance of liquid crystal alignment films and enhance the various characteristics of liquid crystal elements (see, for example, Patent Documents 1 and 2). Patent Document 1 discloses the inclusion of a compound having a structure in which a methylol group is bonded to an aromatic ring as a crosslinking agent, along with polyimide or a polyimide precursor, in the liquid crystal alignment agent. Patent Document 2 also discloses the inclusion of a monofunctional (meth)acrylic compound having a triazine skeleton and a (meth)acryloyloxy group, along with polyimide or a polyimide precursor, in the liquid crystal alignment agent. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2010 / 074269 [Patent Document 2] International Publication No. 2013 / 094618 [Overview of the project] [Problems that the invention aims to solve]

[0005] As the applications of liquid crystal elements expand, they are expected to be used in harsher environments than before. Furthermore, it is conceivable that the liquid crystal alignment film may become more prone to peeling off the substrate when liquid crystal elements are used in harsh environments. In particular, in recent years, sealants are sometimes placed on the liquid crystal alignment film to achieve narrower bezels for liquid crystal panels. In this case, when external force is applied to the liquid crystal element, the liquid crystal alignment film tends to peel off the substrate at the sealant portion. On the other hand, if the liquid crystal alignment film peels off the substrate, there is a concern that it will lead to a decrease in the display quality of the liquid crystal element. Therefore, the liquid crystal alignment film is required to have properties that make it difficult for the liquid crystal alignment film to peel off the substrate even when a sealant is placed on it (hereinafter also referred to as "seal adhesion").

[0006] The transparent conductive film provided on liquid crystal elements is usually formed from an ITO film. While the ITO film has a relatively high refractive index, the liquid crystal alignment film has a relatively low refractive index. Therefore, when attempting to transmit light, such as from a backlight, to the liquid crystal element, reflection is likely to occur at the interface between the transparent conductive film and the liquid crystal alignment film, which tends to reduce the light transmittance of the liquid crystal element. One way to overcome this problem is to increase the refractive index of the liquid crystal alignment film. However, the materials used to increase the refractive index of the film generally have poor solubility, so when the liquid crystal alignment agent is applied to the substrate, unevenness and repulsion are likely to occur, raising concerns that the liquid crystal alignment agent cannot be uniformly applied to the substrate surface. In addition, there are concerns that increasing the refractive index of the liquid crystal alignment film may make afterimages more likely to occur in the liquid crystal element.

[0007] The present invention has been made in view of the above problems, and its main objective is to provide a liquid crystal alignment agent that can form a liquid crystal alignment film with excellent sealing adhesion and a high refractive index, can reduce the generation of afterimages in liquid crystal elements, and has excellent coatability. [Means for solving the problem]

[0008] According to the present invention, the following means are provided. [1] A liquid crystal alignment agent containing a polymer component containing the polymer (A) shown below and a compound (B), wherein the content of the compound (B) is 50 parts by mass or less with respect to 100 parts by mass of the polymer component. (A) Polymer: at least one selected from the group consisting of polyamic acid, polyamic acid ester and polyimide, and * 1 -NR 1 -* 1 , * 1 -NR 1 R 2 , * 1 -NR 1 -CO-* 1 , * 1 -NR 1 -CO-NR 3 -* 1 and at least one selected from the group consisting of nitrogen-containing heterocyclic groups, which is a nitrogen-containing group different from the amino group involved in polymerization (however, R 1 and R 3 are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent thermally dissociable group. R 2 is a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent thermally dissociable group. "* 1 " represents a bond to a carbon atom.) The polymer contains 5 mol% or more of the structural unit (D) derived from a diamine having a nitrogen-containing group different from the amino group involved in polymerization with respect to the total amount of the structural units derived from the diamine compound constituting the polymer (A). (B) Compound: a compound having at least one selected from the group consisting of a naphthalene ring structure, a fluorene ring structure, a carbazole ring structure and a triazine ring structure and a crosslinkable group, and different from the polymer (A) (however, excluding a compound having a triazine ring structure and a (meth)acryloyloxy group and having 1 (meth)acryloyloxy group).

[0009] [2] A liquid crystal alignment film formed using the liquid crystal alignment agent of [1] above. [3] A liquid crystal device including the liquid crystal alignment film of [2] above.

Advantages of the Invention

[0010] The liquid crystal alignment agent of the present invention contains the above-mentioned polymer (A) and compound (B), and by setting the content of compound (B) to a predetermined amount or less, it is possible to form a liquid crystal alignment film that exhibits excellent coatability, excellent seal adhesion, and a high refractive index. Furthermore, according to the liquid crystal alignment agent of the present invention, it is possible to obtain a liquid crystal element in which the generation of afterimages is reduced. [Modes for carrying out the invention]

[0011] Liquid crystal alignment agent The liquid crystal alignment agent of this disclosure contains a polymer component and a compound having a crosslinkable group (hereinafter also referred to as the "crosslinkable group-containing compound"). The components contained in the liquid crystal alignment agent, and other components that may be optionally added as needed, are described below.

[0012] In this specification, "hydrocarbon group" includes linear hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Linear hydrocarbon group" means a linear hydrocarbon group or a branched hydrocarbon group that does not contain a cyclic structure in its main chain and is composed solely of a linear structure. However, linear hydrocarbon groups may be saturated or unsaturated. "Alicyclic hydrocarbon group" means a hydrocarbon group that contains only the structure of an alicyclic hydrocarbon as its ring structure and does not contain an aromatic ring structure. However, an alicyclic hydrocarbon group does not have to be composed solely of the structure of an alicyclic hydrocarbon; it may also include a linear structure as part of it. "Aromatic hydrocarbon group" means a hydrocarbon group that contains an aromatic ring structure as its ring structure. However, an aromatic hydrocarbon group does not have to be composed solely of an aromatic ring structure; it may also include a linear structure or the structure of an alicyclic hydrocarbon as part of it.

[0013] <Polymer components> The liquid crystal alignment agent of this disclosure contains the polymer (A) shown below as a polymer component. (A) Polymer: At least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, * 1 -NR 1 -* 1 , * 1 -NR 1 R2 , * 1 -NR 1 -CO-* 1 , * 1 -NR 1 -CO-NR 3 -* 1 and at least one nitrogen-containing group selected from the group consisting of nitrogen-containing heterocyclic groups, which is different from the amino group involved in polymerization (however, R 1 and R 3 R is independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a monovalent thermally desorbable group. 2 This is a monovalent hydrocarbon group or a monovalent thermally desorbable group having 1 to 10 carbon atoms. 1 A polymer containing 5 mol% or more of structural units (D) derived from a diamine (hereinafter also called "specific diamine") having a bond with a carbon atom, relative to the total amount of structural units derived from the diamine compound constituting the polymer (A).

[0014] (A) Polymer (A) Polymers are * 1 -NR 1 -* 1 , * 1 -NR 1 R 2 , * 1 -NR 1 -CO-* 1 , * 1 -NR 1 -CO-NR 3 -* 1 The structure includes a structural unit having a nitrogen-containing group (hereinafter also referred to as "nitrogen-containing group FN") which is selected from the group consisting of nitrogen-containing heterocyclic groups. The nitrogen-containing group FN is a substructure that is introduced into one or both of the main chain and side chains of polymer (A) without participating in the polymerization reaction when polymerizing monomers containing a specific diamine to obtain polymer (A).

[0015] R 1 , R 2 or R 3Examples of monovalent hydrocarbon groups having 1 to 10 carbon atoms include monovalent linear hydrocarbon groups having 1 to 10 carbon atoms, monovalent alicyclic hydrocarbon groups having 3 to 10 carbon atoms, and monovalent aromatic hydrocarbon groups having 6 to 10 carbon atoms. Of these, alkyl groups, cyclohexyl groups, or phenyl groups having 1 to 6 carbon atoms are preferred, and alkyl groups having 1 to 3 carbon atoms are more preferred. Examples of monovalent thermally detachable groups include tert-butoxycarbonyl group (Boc group), benzyloxycarbonyl group, 1,1-dimethyl-2-haloethyloxycarbonyl group, allyloxycarbonyl group, 2-(trimethylsilyl)ethoxycarbonyl group, and 9-fluorenylmethyloxycarbonyl group. Of these, the Boc group is preferred because it exhibits excellent thermal detachment properties and can reduce the amount of residual structure in the film after detachment. 1 It is preferable that the carbon atom constituting the hydrocarbon group is bonded to it.

[0016] A nitrogen-containing heterocyclic group is an m-valent group (where m is an integer of 1 or more) obtained by removing any m hydrogen atoms from the ring portion of a substituted or unsubstituted nitrogen-containing heterocyclic group. The nitrogen-containing heterocyclic group may be a monocyclic or fused ring, and may be an aromatic or unaromatic ring. Furthermore, the nitrogen-containing heterocyclic group may contain only nitrogen atoms as heteroatoms in the ring portion, or it may contain other atoms (specifically, oxygen atoms or sulfur atoms) along with nitrogen atoms. It is preferable that the nitrogen-containing heterocyclic group FN is a ring having only nitrogen atoms as heteroatoms.

[0017] Specific examples of nitrogen-containing heterocycles include, when the nitrogen-containing heterocycle contained in the nitrogen-containing group FN is a non-aromatic heterocycle, it is preferable that the non-aromatic heterocycle is a piperidine ring or a piperazine ring. Specific examples of nitrogen-containing aromatic heterocycles include pyrrole rings, pyrazole rings, imidazole rings, 1,2,4-triazole rings, 1,2,3-triazole rings, pyridine rings, pyrimidine rings, pyridazine rings, pyrazine rings, 1,2,4-triazine rings, 1,3,5-triazine rings, 1,2,3-triazine rings, carbazole rings, benzimidazole rings, quinoline rings, isoquinoline rings, indole rings, purine rings, acridine rings, oxazole rings, thiazole rings, oxadiazole rings, benzothiazole rings, and the like. The nitrogen-containing aromatic heterocycles included in the nitrogen-containing group FN are preferably pyrrole rings, pyrazole rings, imidazole rings, 1,2,4-triazole rings, 1,2,3-triazole rings, pyridine rings, pyrimidine rings, pyridazine rings, pyrazine rings, 1,2,4-triazine rings, 1,3,5-triazine rings, 1,2,3-triazine rings, carbazole rings, benzimidazole rings, or purine rings, and more preferably pyrazole rings, imidazole rings, 1,2,4-triazole rings, pyridine rings, pyrimidine rings, or benzimidazole rings.

[0018] When the nitrogen-containing heterocycle in the nitrogen-containing group FN has substituents, examples of substituents include halogen atoms, monovalent hydrocarbon groups having 1 to 10 carbon atoms, and monovalent thermally desorbable groups. Of these, alkyl groups or Boc groups having 1 to 3 carbon atoms are preferred, and methyl or ethyl groups are more preferred. From the viewpoint of increasing the refractive index of the liquid crystal alignment film, it is preferable that the nitrogen-containing heterocycle in the nitrogen-containing group FN does not have substituents.

[0019] * 1 -NR 1 -* 1 , * 1 -NR 1 R 2 , * 1 -NR 1 -CO-* 1 and * 1 -NR 1 -CO-NR 3 -*1 may be contained in the linear structure or the cyclic structure of the specific diamine. For example, when the structural unit (D) is * 1 -NR 1 -* 1 has, * 1 -NR 1 -* 1 may be a group constituting a part of the linear structure or a group constituting a part of the piperidine ring or the piperidine ring. When the structural unit (D) is * 1 -NR 1 R 2 , * 1 -NR 1 -CO-* 1 or * 1 -NR 1 -CO-NR 3 -* 1 has, these groups preferably constitute a part of the linear structure.

[0020] The number of nitrogen-containing groups FN in the specific diamine is not particularly limited, and may be 1 or a plurality. Also, when the specific diamine has two or more nitrogen-containing groups FN, the two or more nitrogen-containing groups in the specific diamine may be the same or different from each other. The structural unit (D) may have the nitrogen-containing group FN in the main chain of the polymer or in the side chain. From the viewpoint of being able to further increase the refractive index of the liquid crystal alignment film, the structural unit (D) preferably has the nitrogen-containing group FN in the polymer side chain.

[0021] When the structural unit (D) has the nitrogen-containing group FN in the side chain, from the viewpoint of further increasing the refractive index of the liquid crystal alignment film, R 1 , R 2 and R 3 in the nitrogen-containing group FN are preferably a hydrogen atom, a methyl group or an ethyl group, and more preferably a hydrogen atom. Also, when the structural unit (D) has the nitrogen-containing group FN in the main chain of the polymer, the nitrogen-containing group FN is * 1 -NR 1 -* 1 , * 1 -NR 1 -CO-* 1 , * 1 -NR1 -CO-NR 3 -* 1 Preferably, it is at least one selected from the group consisting of and nitrogen-containing heterocyclic groups.

[0022] Specific examples of specific diamines include 4,4'-diaminodiphenylamine, 1,4-bis-(4-aminophenyl)-piperazine, 4,4'-[4,4'-propane-1,3-diylbis(piperidine-1,4-diyl)]dianiline, 4,4'-diaminobenzanilide, N,N'-bis(4-aminophenyl)-benzidine, N,N'-bis(4-aminophenyl)-N,N'-dimethylbenzidine, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, and compounds represented by formulas (da-1) to (da-44) below. [ka] [ka] [ka] [ka] (In equation (da-34), t is an integer between 1 and 10.) [ka]

[0023] (A) The content of structural unit (D) in polymer is 5 mol% or more relative to the total amount of structural units derived from the diamine compound contained in polymer (A). If the content of structural unit (D) is less than 5 mol%, a highly refractory liquid crystal alignment film cannot be obtained, and the transmittance of the liquid crystal element tends to decrease, or afterimages tend to occur in the liquid crystal element. From these viewpoints, the content of structural unit (D) in polymer (A) is more preferably 7 mol% or more, and even more preferably 10 mol% or more, relative to the total amount of structural units derived from the diamine compound contained in polymer (A). Furthermore, from the viewpoint of suppressing a decrease in the refractive index of the liquid crystal alignment film and suppressing a decrease in coatability due to polymer aggregation, the content of structural unit (D) is preferably 90 mol% or less, more preferably 85 mol% or less, and even more preferably 80 mol% or less, relative to the total amount of structural units derived from the diamine compound contained in polymer (A).

[0024] (A) The polymer is at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide. (A) The polymer can be obtained by polycondensation reaction of a tetracarboxylic acid derivative with a diamine. In this specification, the term tetracarboxylic acid derivative includes tetracarboxylic acid dianhydrides, tetracarboxylic acid diesters, and tetracarboxylic acid diester halides.

[0025] (Polyamic acid) (A) Polyamic acid as a polymer (hereinafter also referred to as "polyamic acid (A)") can be obtained by reacting a tetracarboxylic dianhydride with a diamine compound.

[0026] Examples of tetracarboxylic dianhydrides used in the synthesis of polyamic acid (A) include aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides. Aliphatic tetracarboxylic dianhydrides include linear tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides.

[0027] Specific examples of these include 1,2,3,4-butanetetracarboxylic dianhydride, which is a chain-like tetracarboxylic dianhydride. Examples of alicyclic tetracarboxylic dianhydrides include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid 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-tetracarboxybicyclo[3.3.0]octane-2:4,6:8-dianhydride, cyclopentanetetracarboxylic dianhydride, and cyclohexanetetracarboxylic dianhydride.

[0028] Examples of aromatic tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, ethylene glycol bisanhydrotrimate, 4,4'-carbonyl diphthalic anhydride, and 4,4'-oxyphthalic anhydride. In addition, tetracarboxylic dianhydrides described in Japanese Patent Publication No. 2010-97188 can also be used. Tetracarboxylic dianhydrides can be used individually or in combination of two or more.

[0029] (A) Polymers preferably contain structural units derived from aromatic tetracarboxylic acid derivatives, as this allows for a higher refractive index of the liquid crystal alignment film and enables the production of liquid crystal elements with reduced afterimages. Therefore, when obtaining polyamic acid (A) as polymer (A), it is preferable that the tetracarboxylic dianhydride used in the synthesis of polyamic acid (A) contains aromatic tetracarboxylic dianhydride. From the above viewpoint, it is more preferable that the aromatic tetracarboxylic acid derivative used in the production of polymer (A) contains at least one selected from the group consisting of pyromellitic acid derivatives and biphenyltetracarboxylic acid derivatives.

[0030] Specific examples of pyromellitic acid derivatives include pyromellitic acid dianhydride, pyromellitic acid diester, and pyromellitic acid diester dihalides. Specific examples of biphenyltetracarboxylic acid derivatives include 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid diester, and 3,3',4,4'-biphenyltetracarboxylic acid diester dihalides.

[0031] (A) In polymer, the content of structural units derived from aromatic tetracarboxylic acid derivatives is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, relative to the total amount of structural units derived from tetracarboxylic acid derivatives in polymer (A). Furthermore, from the viewpoint of ensuring the solubility of polymer (A), the content of structural units derived from aromatic tetracarboxylic acid derivatives is preferably 80 mol% or less, more preferably 70 mol% or less, and even more preferably 60 mol% or less, relative to the total amount of structural units derived from tetracarboxylic acid derivatives in polymer (A).

[0032] (A) The diamine compound used in the synthesis of polyamic acid contains at least a specific diamine. In addition, (A) the specific diamine and other diamines may be used in combination in the synthesis of polyamic acid. As other diamines, known diamines used in the synthesis of polyamic acid can be used. Examples of such diamines include aliphatic diamines, aromatic diamines, and diaminoorganosiloxanes. Aliphatic diamines include linear diamines and alicyclic diamines.

[0033] Other specific examples of diamines include chain-type diamines such as metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, and hexamethylenediamine. Examples of alicyclic diamines include 1,4-diaminocyclohexane and 4,4'-methylenebis(cyclohexylamine).

[0034] Aromatic diamines include p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4-aminophenyl-4-aminobenzoate, 4,4'-diaminoazobenzene, 1,5-bis(4-aminophenoxy)pentane, 1,2-bis(4-aminophenoxy)ethane, 1,6-bis(4-aminophenoxy)hexane, bis[2-(4-aminophenyl)ethyl]hexanediacid, 2,2'-dimethyl-4,4'-diaminobiphenyl, and 2,2'-bis(trifluoromethyl)-4 Main-chain diamines such as ,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(phenylenediisopropylidene)bisaniline, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diaminosylbenzene, 3,5-diaminobenzoic acid, and 2,4-diaminobenzoic acid: Dodecanoxy-2,4-diaminobenzene, pentadecanoxy-2,4-diaminobenzene, hexadecanoxy-2,4-diaminobenzene, octadecanoxy-2,4-diaminobenzene, pentadecanoxy-2,5-diaminobenzene, octadecanoxy-2,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestenyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, lanostanyl 3,5-diaminobenzoate, 3,6-bis(4-aminobenzoyloxy)cholestane, 3,6-bis(4-aminophenoxy)cholestane, 4-(4'-trifluoromethoxybenzoyloxy)cyclohexyl 3,5-diaminobenzoate, 1,1-bis(4-((aminophenyl)methyl)phenyl)-4-butylcyclohexane, cholestan-3-yl 3,5-diaminobenzoate, the following formula (E-1) [Chemical formula] (In formula (E-1), X I and X II are each independently a single bond, -O-, *-COO- or *-OCO- (where "*" represents the bond to X I ).) R I is an alkanediyl group having 1 to 3 carbon atoms. R II s is a single bond or an alkanediyl group having 1 to 3 carbon atoms. R III is an alkyl group, an alkoxy group, a fluoroalkyl group, or a fluoroalkoxy group having 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. However, 1≤a + b + c≤3.) Side-chain diamines such as the compound represented by Examples of diaminoorganosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, and diamines described in Japanese Patent Publication No. 2010-97188 can also be used. In the synthesis of polyamic acid, the diamine compound can be used individually or in combination of two or more.

[0035] (A) The polymer preferably further contains structural unit (D) and structural unit (C) which is derived from a diamine having a carboxyl group and is different from structural unit (D). By further containing structural unit (C) in polymer (A), it is possible to increase the refractive index of the liquid crystal alignment film and improve the seal adhesion, and to obtain a liquid crystal element in which the generation of afterimages is further reduced. The reason for these effects is thought to be due to the interaction between the nitrogen-containing group of structural unit (D) and the carboxyl group of structural unit (C), although this does not limit the present invention.

[0036] Specific examples of diamines that provide a structural unit (C) include, for example, the compounds represented by formulas (dc-1) to (dc-7) below. [ka]

[0037] (A) When the polymer contains structural unit (C), the content of structural unit (C) is preferably 2 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, relative to the total amount of structural units derived from the diamine compound in polymer (A). Furthermore, the content of structural unit (C) is preferably 60 mol% or less, and more preferably 50 mol% or less, relative to the total amount of structural units derived from the diamine compound in polymer (A). By setting the content of structural unit (C) within the above range, it is possible to further increase the refractive index of the liquid crystal alignment film and improve the seal adhesion, and to obtain a liquid crystal element in which the generation of afterimages is further reduced.

[0038] Polyamic acid (A) can be obtained by reacting a tetracarboxylic dianhydride and a diamine as described above, together with a molecular weight modifier as needed. The preferred ratio of tetracarboxylic dianhydride and diamine compound used in the synthesis reaction of polyamic acid (A) is such that the acid anhydride groups of the tetracarboxylic dianhydride are 0.2 to 2 equivalents per 1 equivalent of amino groups of the diamine compound. Examples of molecular weight modifiers include acid monoanhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride; monoamine compounds such as aniline, cyclohexylamine, and n-butylamine; and monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate. The preferred ratio of molecular weight modifier is 20 parts by mass or less per 100 parts by mass of the total amount of tetracarboxylic dianhydride and diamine compound used.

[0039] The synthesis reaction of polyamic acid (A) 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 to 24 hours. 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, hexamethylphosphortriamide, m-cresol, xylenol, and halogenated phenol, or a mixture of one or more of these and another organic solvent (e.g., butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount of organic solvent used (a) is preferably such that the total amount of tetracarboxylic dianhydride and diamine (b) is 0.1 to 50% by mass of the total amount of the reaction solution (a + b).

[0040] As described above, a reaction solution is obtained by dissolving polyamic acid (A). This reaction solution may be used directly for the preparation of the liquid crystal alignment agent, or the polyamic acid (A) contained in the reaction solution may be isolated before being used for the preparation of the liquid crystal alignment agent.

[0041] (Polyamic acid ester) (A) Polyamic acid esters as polymers can be obtained, for example, by [I] reacting the polyamic acid (A) obtained by the above synthesis reaction with an esterifying agent, [II] reacting a tetracarboxylic acid diester with a diamine compound, [III] reacting a tetracarboxylic acid dihalide with a diamine compound, etc. According to these methods [I] to [III], polyamic acid esters can be obtained by polycondensation reaction between a tetracarboxylic acid derivative and a diamine compound. The polyamic acid ester to be contained in the liquid crystal alignment agent may have only an amic acid ester structure, or it may be a partially esterified product in which both an amic acid structure and an amic acid ester structure coexist. The reaction solution obtained by dissolving the polyamic acid ester may be used as is for the preparation of the liquid crystal alignment agent, or the polyamic acid ester contained in the reaction solution may be isolated before being used for the preparation of the liquid crystal alignment agent.

[0042] (Polyimide) (A) Polyimide as a polymer can be obtained, for example, by dehydrating and cyclizing polyamic acid (A) synthesized as described above to imide it. Polyimide may be a complete imidide obtained by dehydrating and cyclizing all of the amic acid structure that the precursor polyamic acid had, or it may be a partial imidide obtained by dehydrating and cyclizing only a part of the amic acid structure, in which amic acid structure and imide ring structure coexist. The polyimide used in the preparation of liquid crystal alignment agents preferably has an imidization rate of 20 to 99%, and more preferably 30 to 90%. This imidization rate is expressed as a percentage of the ratio of the number of imide ring structures to the total number of amic acid structures and imide ring structures of the polyimide. Here, part of the imide ring may be an isoimide ring.

[0043] Dehydration and ring closure of polyamic acid (A) is preferably carried out by dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration and ring closure catalyst to the solution, and heating as necessary. In this method, as the dehydrating agent, for example, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used. The amount of dehydrating agent used is preferably 0.01 to 20 moles per mole of the amic acid structure of polyamic acid (A). As the dehydration and ring closure catalyst, for example, tertiary amines such as pyridine, colidine, lutidine, and triethylamine can be used. The amount of dehydration and ring closure catalyst used is preferably 0.01 to 10 moles per mole of the dehydrating agent used. Examples of organic solvents used in the dehydration and ring closure reaction include the organic solvents exemplified for use in the synthesis of polyamic acid (A). The reaction temperature for the dehydration and ring closure reaction is preferably 0 to 180°C. The reaction time is preferably 1.0 to 120 hours. The reaction solution containing the polyimide obtained by the above reaction may be used directly for the preparation of the liquid crystal alignment agent, or the polyimide may be isolated before being used for the preparation of the liquid crystal alignment agent. The polyimide can also be obtained by imidization of a polyamic acid ester.

[0044] The solution viscosity of polymer (A) contained in the liquid crystal alignment agent is preferably 10 to 800 mPa·s when it is a 10% by mass solution, and more preferably 15 to 500 mPa·s. The solution viscosity (mPa·s) is the value measured at 25°C using an E-type rotational viscometer for a 10% by mass polymer solution prepared using a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0045] (A) The weight-average molecular weight (Mw) of the polymer in terms of polystyrene, as measured by gel permeation chromatography (GPC), is preferably 1,000 to 500,000, and 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) in terms of polystyrene, as measured by GPC, is preferably 15 or less, and more preferably 10 or less.

[0046] Furthermore, when imparting liquid crystal alignment ability to an organic film formed using a liquid crystal alignment agent using a photo-alignment method, a photo-aligned film can be obtained by making at least a portion of the polymer component a polymer having a photo-aligning group. Here, a photo-aligning group refers to a functional group that can impart anisotropy to a film through photoreactions such as photoisomerization, photodimerization, photofleece rearrangement, or photodegradation by light irradiation. A polymer (A) having a photo-aligning group can be obtained, for example, by polymerization using a tetracarboxylic acid derivative having a cyclobutane ring structure, a diamine having a cinnamate structure, etc.

[0047] The polymer component contained in the liquid crystal alignment agent of this disclosure may consist only of polymer (A), but may also include polymers other than (A) (hereinafter also referred to as "other polymers").

[0048] The main skeleton of other polymers is not particularly limited. Examples of other polymers include polyamic acid, polyamic acid esters, polyimides, polyamines, polyenamines, polyorganosiloxanes, polyesters, polyamides, polyamideimides, polystyrene, polybenzoxazole precursors, polybenzoxazoles, cellulose derivatives, polyacetals, polymaleimides, and addition polymers (e.g., styrene-maleimide copolymers, styrene polymers, maleimide polymers, poly(meth)acrylates). Note that (meth)acrylate refers to both acrylate and methacrylate. Polyenamines are polymers having a carbon-carbon double bond adjacent to the amino group of a polyamine, and examples include polyenaminoketones, polyenaminoesters, polyenaminonitriles, and polyenaminosulfonyls.

[0049] Of the other polymers, at least one selected from the group consisting of polyamic acids, polyamic acid esters, polyimides, polyorganosiloxanes, and addition polymers is preferred because it allows for the creation of liquid crystal elements with superior liquid crystal alignment and electrical properties.

[0050] Other polymers may be used individually or in combination. For example, a first polymer and a second polymer having higher polarity than the first polymer may be included in the liquid crystal alignment agent. This is preferable because the second polymer with higher polarity will be unevenly distributed in the lower layer and the first polymer will be unevenly distributed in the upper layer, allowing for phase separation. Preferred embodiments of the polymer component of the liquid crystal alignment agent include the following (I) to (III). (I) A manifestation in which the first polymer and the second polymer are polymers selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide. (II) An embodiment in which one of the first polymer and the second polymer is a polymer selected from the group consisting of polyamic acid, polyamic acid ester and polyimide, and the other is a polyorganosiloxane. (III) An embodiment in which one of the first polymer and the second polymer is at least one polymer selected from the group consisting of polyamic acid, polyamic acid ester and polyimide, and the other is an addition polymer.

[0051] The polymer components contained in the liquid crystal alignment agent of this disclosure can further improve the refractive index and seal adhesion of the liquid crystal alignment film, and it is preferable that at least one selected from the group consisting of polymer (A) and other polymers contains a structural unit derived from a diamine having a carboxyl group, in order to obtain a liquid crystal element with further reduced afterimage generation. Therefore, if polymer (A) does not have structural unit (C), the liquid crystal alignment agent of this disclosure preferably contains other polymers, and it is preferable that the other polymers contain a structural unit having a carboxyl group.

[0052] Other methods for obtaining polymers containing structural units having carboxyl groups can be appropriately selected depending on the main skeleton of the polymer. For example, if the other polymer is a polymer selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, a polymer containing structural units having carboxyl groups can be obtained by polymerization using a diamine that gives the structural unit (C) described above. Also, if the other polymer is an addition polymer, a polymer containing structural units having carboxyl groups can be obtained by polymerization using an unsaturated carboxylic acid (e.g., (meth)acrylic acid, maleic acid, fumaric acid, etc.).

[0053] If the other polymer contains structural units having a carboxyl group, the content of such structural units is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 15 mol% or more, relative to the total amount of structural units in the other polymer. Furthermore, the content of structural units having a carboxyl group is preferably 70 mol% or less, and more preferably 60 mol% or less, relative to the total amount of structural units in the other polymer.

[0054] From the viewpoint of increasing the refractive index of the liquid crystal alignment film, further improving the seal adhesion, and obtaining a liquid crystal element with reduced afterimage generation, it is preferable that the liquid crystal alignment agent of this disclosure satisfies either (A) polymer further containing structural unit (C), or further containing a polymer containing a structural unit having a carboxyl group as another polymer, or both. In particular, using a polymer further containing structural unit (C) as polymer (A) is preferable because it is possible to obtain a liquid crystal element with reduced afterimage generation.

[0055] The content of polymer components in the liquid crystal alignment agent is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on the total mass of solids contained in the liquid crystal alignment agent (i.e., the total mass of components other than the solvent in the liquid crystal alignment agent). Furthermore, the content of (A) polymer is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more, based on 100 parts by mass of the total amount of polymer components in the liquid crystal alignment agent.

[0056] <(B) Compound> The liquid crystal alignment agent of this disclosure contains the following compound (B) as a crosslinkable group-containing compound. (B) Compound: A compound having at least one selected from the group consisting of a naphthalene ring structure, a fluorene ring structure, a carbazole ring structure, and a triazine ring structure (hereinafter also referred to as "specific ring structure") and a crosslinkable group, and different from the polymer (A). However, compound (B) included in the liquid crystal alignment agent of this disclosure is a different compound from a compound having a triazine ring structure and a (meth)acryloyloxy group, and having one (meth)acryloyloxy group.

[0057] (B) Compound is a different component from (A) polymer. The molecular weight of (B) compound is preferably 3,000 or less, more preferably 2,000 or less, and even more preferably 1,000 or less, from the viewpoint of obtaining a liquid crystal alignment film with higher seal adhesion.

[0058] (B) The crosslinkable group of compound (B) is preferably a group that can react with the functional group of polymer (A). In particular, the crosslinkable group of compound (B) is preferably at least one selected from the group consisting of methylol group, alkoxymethyl group, hydroxyalkylamide group, alkoxysilyl group, oxyranyl group, oxetanyl group, and carbon-carbon unsaturated bond-containing group.

[0059] Here, the alkoxy group of the alkoxymethyl group and the alkoxysilyl group is preferably having 1 to 4 carbon atoms, more preferably 1 to 3 carbon atoms, and even more preferably a methoxy group or an ethoxy group, from the viewpoint of reactivity. The alkyl group of the hydroxyalkylamide group is preferably having 1 to 5 carbon atoms, and more preferably 2 to 4 carbon atoms. Examples of carbon-carbon unsaturated bond-containing groups include (meth)acryloyloxy group, (meth)acryloylamino group, vinyl group, vinylphenyl group, vinyl ether group, maleimide group, etc.

[0060] In terms of improving the seal adhesion and refractive index of the liquid crystal alignment film, the crosslinkable group is more preferably at least one selected from the group consisting of methylol group, alkoxymethyl group, hydroxyalkylamide group, alkoxysilyl group, oxyranyl group, and oxetanyl group, and even more preferably at least one selected from the group consisting of methylol group, alkoxymethyl group, and hydroxyalkylamide group.

[0061] The number of crosslinkable groups in one molecule of compound (B) is preferably two or more, more preferably 2 to 10, and even more preferably 3 to 8, in order to further enhance the seal adhesion and refractive index improvement effect of the liquid crystal alignment film. In the case of alkoxysilyl groups, the number of alkoxy groups corresponds to the number of crosslinkable groups, and in the case of hydroxyalkylamide groups, the number of hydroxyalkyl groups corresponds to the number of crosslinkable groups. For example, if compound (B) has three triethoxysilyl groups (-Si(OC2H5)3) in one molecule, the total number of triethoxy groups (-OC2H5) (9) is the number of crosslinkable groups in compound (B). Also, if compound (B) has two "-CO-N(C2H4OH)2" hydroxyethylamide groups in one molecule, the total number of hydroxyethyl groups (-OC2H4OH) (4) is the number of crosslinkable groups in compound (B).

[0062] (B) The compound is preferably a compound represented by the following formula (1). [ka] (In formula (1), X 1 R is a methylol group, alkoxymethyl group, hydroxyalkylamide group, alkoxysilyl group, oxyranyl group, oxetanyl group, or a carbon-carbon unsaturated bond-containing group. 5 This is an m-valent group having a naphthalene ring structure, a fluorene ring structure, a carbazole ring structure, or a triazine ring structure. m is an integer from 2 to 10. Multiple X in the formula 1 They are either identical or different from one another.

[0063] In the above equation (1), R 5 Examples of m-valent groups represented by include organic groups having 3 to 40 carbon atoms that have a naphthalene ring structure, a fluorene ring structure, a carbazole ring structure, or a triazine ring structure. 5 The m-valent group represented by may have either a chain structure or a cyclic structure, or both, together with a naphthalene ring, a fluorene ring, a carbazole ring, or a triazine ring. Also, X 1 The crosslinking group represented by R 5 The naphthalene ring, fluorene ring, carbazole ring, or triazine ring may be directly bonded to the naphthalene ring, fluorene ring, carbazole ring, or triazine ring within the molecule, or it may be bonded via either or both a chain structure and a cyclic structure.

[0064] (B)Specific examples of compounds include those represented by formulas (a-1) to (a-4), (b-1) to (b-4), (c-1) to (c-4), and (e-1) to (e-5), respectively. [ka] [ka] [ka] [ka]

[0065] (B) The content of compound (B) is 50 parts by mass or less per 100 parts by mass of polymer component contained in the liquid crystal alignment agent. If the content of compound (B) exceeds 50 parts by mass, it leads to a decrease in the strength of the liquid crystal alignment film and poor seal adhesion. In addition, an excessive amount of compound (B) can lead to a decrease in the afterimage characteristics of the liquid crystal element, and the compound (B) tends to aggregate, which can reduce the coatability of the liquid crystal alignment agent. From these viewpoints, the content of compound (B) is preferably 45 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less, per 100 parts by mass of polymer component contained in the liquid crystal alignment agent. Furthermore, from the viewpoint of sufficiently obtaining the improvement effect of the refractive index of the liquid crystal alignment film, seal adhesion, and coatability of the liquid crystal alignment agent by incorporating compound (B), and from the viewpoint of obtaining a liquid crystal element in which the generation of afterimages is sufficiently suppressed, the content of compound (B) is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, per 100 parts by mass of polymer component contained in the liquid crystal alignment agent. (B) The compound may be used individually or in combination of two or more compounds.

[0066] <Other ingredients> The liquid crystal alignment agent of this disclosure may further contain components other than polymer components and (B) compounds (hereinafter also referred to as other components) as needed. Specific examples of other components include crosslinkable group-containing compounds that do not have the above-mentioned specific ring structure, antioxidants, metal chelating compounds, curing accelerators, surfactants, fillers, dispersants, photosensitizers, solvents, etc. The content of the other compounds can be appropriately selected depending on each compound, within a range that does not impair the effects of this disclosure.

[0067] (solvent) The liquid crystal alignment agent of this disclosure is preferably prepared as a liquid composition in which a polymer component, a compound (B), and optionally added components are dissolved in a solvent. The solvent is preferably an organic solvent, such as aprotic polar solvents, phenolic solvents, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc.

[0068] Specific examples of organic solvents used include, for example, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolidinone, γ-butyrolactone, γ-butyrolactam, 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, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, and ethylene glycol-n Examples include 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, diisopentyl ether, ethylene carbonate, propylene carbonate, cyclohexanone, diisobutyl ketone, 3-methoxy-1-butanol, etc. These can be used individually or in combination of two or more.

[0069] The solid content concentration in the liquid crystal alignment agent (the ratio of the total mass of components other than the solvent to the total mass of the liquid crystal alignment agent) is appropriately selected considering viscosity, volatility, etc., but is preferably in the range of 1 to 10% by mass. When the solid content concentration is 1% by mass or more, it is possible to ensure sufficient film thickness of the coating and tend to yield a good liquid crystal alignment film. On the other hand, when the solid content concentration is 10% by mass or less, the film thickness of the coating does not become excessive, and the viscosity of the liquid crystal alignment agent can be made moderately high, which tends to result in good coatability.

[0070] <Liquid crystal alignment films and liquid crystal elements> The liquid crystal alignment film of this disclosure is formed from a liquid crystal alignment agent prepared as described above. The liquid crystal element of this disclosure comprises 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 TN type, STN type, VA type (including VA-MVA type, VA-PVA type, etc.), IPS (In-Plane Switching) type, FFS (Fringe Field Switching) type, OCB (Optically Compensated Bend) type, and PSA (Polymer Sustained Alignment) type. The liquid crystal element can be manufactured by a method including, for example, the following steps 1 to 3. In step 1, the substrate used differs depending on the desired operating mode. Steps 2 and 3 are common to each operating mode.

[0071] <Step 1: Formation of the coating> First, a liquid crystal alignment agent is applied to the substrate, and preferably the applied surface is heated to form a coating on the substrate. For example, transparent substrates made of glass such as float glass or soda glass, or resins such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, or poly(alicyclic olefin) can be used as the substrate. As the transparent conductive film provided on one surface of the substrate, NESA films (registered trademark of PPG, Inc., USA) made of tin oxide (SnO2), ITO films made of indium oxide-tin oxide (In2O3-SnO2), etc., can be used. When manufacturing TN, STN, or VA type liquid crystal elements, two substrates with patterned transparent conductive films are used. On the other hand, when manufacturing IPS or FFS type liquid crystal elements, a substrate with comb-shaped patterned electrodes and a counter substrate without electrodes are used. The liquid crystal alignment agent is applied to the substrate on the electrode formation surface, preferably by offset printing, flexographic printing, spin coating, roll coating, or inkjet printing.

[0072] After applying the liquid crystal alignment agent, preheating (pre-bake) is preferably performed to prevent dripping of the applied liquid crystal alignment agent. The pre-bake temperature is preferably 30 to 200°C, and the pre-bake time is preferably 0.25 to 10 minutes. Subsequently, a firing (post-bake) process is performed to further remove the solvent. The firing temperature (post-bake temperature) at this time is preferably 80 to 250°C, more preferably 80 to 200°C. The post-bake time is preferably 5 to 200 minutes. The film thickness of the film formed in this way is preferably 0.001 to 1 μm.

[0073] <Step 2: Orientation Treatment> When manufacturing TN, STN, IPS, or FFS type liquid crystal elements, a process (alignment treatment) is performed to impart liquid crystal alignment ability to the coating film formed in step 1 above. This imparts the liquid crystal molecule alignment ability to the coating film, making it a liquid crystal alignment film. As an alignment treatment, methods such as rubbing, in which the coating film formed on the substrate is rubbed in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton, or photo-alignment, in which light is irradiated onto the coating film formed on the substrate to impart liquid crystal alignment ability to the coating film, can be used. On the other hand, when manufacturing vertical alignment (VA) type liquid crystal elements, the coating film formed in step 1 above can be used as is as a liquid crystal alignment film, but an alignment treatment may be applied to the coating film to further enhance its liquid crystal alignment ability. A liquid crystal alignment film suitable for vertical alignment type liquid crystal elements is also suitable for PSA type liquid crystal elements.

[0074] In the photo-alignment process, light irradiation can be performed by methods such as irradiating the coating film after the post-bake process, irradiating the coating film after the pre-bake process but before the post-bake process, or irradiating the coating film while it is being heated in at least one of the pre-bake or post-bake processes. As radiation to irradiate the coating film, for example, ultraviolet light and visible light including light with wavelengths of 150 to 800 nm can be used. Preferably, ultraviolet light including light with wavelengths of 200 to 400 nm is used. If the radiation is polarized, it may be linearly polarized or partially polarized. If the radiation used is linearly polarized or partially polarized, irradiation may be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these. In the case of unpolarized radiation, the irradiation direction should be oblique.

[0075] Examples of light sources that can be used include low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonance lamps, xenon lamps, and excimer lasers. The radiation dose to the substrate surface is preferably 400 to 50,000 J / m². 2 And more preferably 1,000 to 20,000 J / m 2 In addition, after light irradiation to impart orientation ability, the substrate surface may be washed with, for example, water, an organic solvent (e.g., methanol, isopropyl alcohol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.), or a mixture thereof, or the substrate may be heated.

[0076] <Step 3: Liquid Crystal Cell Construction> Two substrates with liquid crystal alignment films formed on them as described above are prepared, and a liquid crystal cell is manufactured between the two substrates so that liquid crystal is arranged adjacent to the liquid crystal alignment film. To manufacture the liquid crystal cell, for example, two substrates are placed opposite each other with a gap in between so that the liquid crystal alignment films face each other, the periphery of the two substrates is bonded together with a sealant, and liquid crystal is injected and filled into the cell gap surrounded by the substrate surface and the sealant, sealing the injection hole, or an ODF method can be used. As the sealant, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as spacers can be used. As the liquid crystal, nematic liquid crystal and smectic liquid crystal can be used, and among these, nematic liquid crystal is preferred. In PSA mode, after the construction of the liquid crystal cell, a voltage is applied between the conductive films of the pair of substrates, and the liquid crystal cell is irradiated with light.

[0077] PSA-type liquid crystal elements can be manufactured by a method that includes the following steps. A step of forming a coating film by applying the liquid crystal alignment agent of this disclosure onto the conductive film of each of a pair of substrates having a conductive film. A process for constructing a liquid crystal cell by arranging a pair of substrates coated with a liquid crystal alignment agent so that the coating films face each other with a liquid crystal layer in between. • A process of applying a voltage between conductive films and irradiating a liquid crystal cell with light.

[0078] Specifically, a liquid crystal cell is constructed in the same manner as in steps 1 to 3 above, except that a photopolymerizable monomer is injected or dropped together with the liquid crystal between a pair of substrates having a conductive film. Conventionally known compounds can be used as the photopolymerizable monomer injected or dropped together with the liquid crystal. Preferably, it is a polyfunctional (meth)acrylic monomer.

[0079] In the manufacturing of PSA-type liquid crystal elements, after constructing the liquid crystal cell, a voltage is applied between the conductive films of a pair of substrates, and the liquid crystal cell is irradiated with light. The applied voltage can be, for example, 5 to 50 V DC or AC. As the irradiated light, ultraviolet light and visible light including wavelengths of 150 to 800 nm can be used. Of these, ultraviolet light including wavelengths of 300 to 400 nm is preferred. As the light source for the irradiation light, 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, an excimer laser, etc. can be used. The amount of light irradiated is preferably 1,000 to 200,000 J / m 2 More preferably, 1,000 to 100,000 J / m 2 That is the case.

[0080] For each mode of liquid crystal cell, a polarizing plate is then attached to the outer surface of the liquid crystal cell as needed to form a liquid crystal element. Examples of polarizing plates include a polarizing plate made by sandwiching a polarizing film called an "H film," which is made by stretching and oriented polyvinyl alcohol while absorbing iodine, between cellulose acetate protective films, or a polarizing plate made of the H film itself.

[0081] The liquid crystal elements of this disclosure can be effectively applied to a variety of applications. Specifically, they can be applied to various display devices such as watches, portable game consoles, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, information displays, as well as dimming films, phase difference films, and the like.

[0082] Based on the details of this disclosure described above, the following means are provided. [Method 1] A liquid crystal alignment agent comprising a polymer component containing the polymer (A) described above and a compound (B) described above, wherein the content of compound (B) is 50 parts by mass or less per 100 parts by mass of the polymer component. [Method 2] The liquid crystal alignment agent according to [Method 1], wherein the polymer (A) contains structural units derived from an aromatic tetracarboxylic acid derivative. [Method 3] The liquid crystal alignment agent according to [Method 2], wherein the aromatic tetracarboxylic acid derivative comprises at least one selected from the group consisting of pyromellitic acid derivatives and biphenyltetracarboxylic acid derivatives. [Method 4] A liquid crystal alignment agent according to any one of [Method 1] to [Method 3], wherein at least one selected from the group consisting of polymer (A) and polymers different from polymer (A) contains a structural unit derived from a diamine having a carboxyl group (excluding structural unit (D)). [Method 5] The liquid crystal alignment agent according to any one of [Method 1] to [Method 4], wherein the structural unit (D) has the nitrogen-containing group in the side chain of the polymer. [Method 6] The nitrogen-containing group is * 1 -NR 1 -* 1 , * 1 -NR 1 -CO-* 1 , * 1 -NR 1 -CO-NR 3 -* 1 A liquid crystal alignment agent according to any one of the means 1 to 5, wherein the structural unit (D) is at least one selected from the group consisting of and nitrogen-containing heterocyclic groups, and the nitrogen-containing group is present in the main chain of the polymer. [Method 7] The liquid crystal alignment agent according to any one of [Method 1] to [Method 6], wherein the crosslinkable group of compound (B) is at least one selected from the group consisting of a methylol group, an alkoxymethyl group, a hydroxyalkylamide group, an alkoxysilyl group, an oxyranyl group, an oxetanyl group, and a carbon-carbon unsaturated bond-containing group. [Method 8] A liquid crystal alignment agent according to any one of [Method 1] to [Method 7], wherein the content of compound (B) is 0.1 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the polymer component. [Method 9] A liquid crystal alignment agent according to any one of [Method 1] to [Method 8], wherein the content of the structural unit (D) in the polymer (A) is 85 mol% or less relative to the total amount of structural units derived from the diamine. [Method 10] A liquid crystal alignment agent according to any one of [Method 1] to [Method 9], further comprising a polymer different from the polymer (A) mentioned above. [Method 11] The liquid crystal alignment agent according to [Method 10], wherein the polymer different from polymer (A) is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane and addition polymer. [Method 12] A liquid crystal alignment film formed using a liquid crystal alignment agent described in any of [Method 1] to [Method 11]. [Method 13] A liquid crystal element comprising the liquid crystal alignment film described in [Method 12]. [Examples]

[0083] The present invention will be described in detail below with reference to examples, but it is not limited to the following examples.

[0084] In the following examples, the solution viscosity, weight-average molecular weight (Mw), and number-average molecular weight (Mn) of the polymer, as well as the imidation rate of the polyimide, were measured by the following methods. <Solution viscosity of polymers> The solution viscosity of the polymer was measured at 25°C using an E-type viscometer. <Weight-average molecular weight and number-average molecular weight> Mw and Mn were measured by gel permeation chromatography (GPC) under the following conditions. The molecular weight distribution (Mw / Mn) was calculated from the obtained Mw and Mn values. Equipment: Showa Denko Corporation's "GPC-101" GPC columns: Combining "GPC-KF-801", "GPC-KF-802", "GPC-KF-803", and "GPC-KF-804" manufactured by Shimadzu GLC Co., Ltd. Mobile phase: Tetrahydrofuran (THF) Column temperature: 40℃ Flow rate: 1.0mL / min Sample concentration: 1.0% by mass Sample injection volume: 100 μL Detector: Differential refractometer Standard material: Monodisperse polystyrene <Imidification rate of polyimides> A polyimide solution was added to pure water, and the resulting precipitate was thoroughly dried under reduced pressure at room temperature. Then it was dissolved in deuterated dimethyl sulfoxide, with tetramethylsilane as the reference material, at room temperature. 1 1H-NMR measurements were performed. 1 The imidization rate [%] was determined from the 1H-NMR spectrum using the following formula (1). Imidization rate [%] = (1 - (β 1 / ( β 2 ×α)))×100 …(1) (In formula (1), β 1 This represents the peak area originating from the proton of the NH group, appearing around a chemical shift of 10 ppm, and β 2 α represents the peak area derived from other protons, and α is the ratio of other protons to one proton of the NH group in the polymer precursor (polyamic acid).

[0085] The abbreviations for the compounds used in the examples below are shown below. For convenience, the compound represented by formula (X) may be simply referred to as "compound (X)" below. [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0086] <Synthesis of polymers> 1. Synthesis of polyimides [Synthesis Example 1] A solution containing 20% ​​by mass of polyamic acid was obtained by dissolving 30 mole parts of compound (T-1), 10 mole parts of compound (T-2), 40 mole parts of compound (T-3), and 20 mole parts of compound (T-5) as tetracarboxylic dianhydrides, and 20 mole parts of compound (D-1), 30 mole parts of compound (D-3), 30 mole parts of compound (D-4), and 20 mole parts of compound (D-13) as diamine compounds in N-methyl-2-pyrrolidone (NMP) and reacting at 40°C for 24 hours. Next, NMP was added to the obtained polyamic acid solution, and pyridine and acetic anhydride were added in amounts of 3 mole equivalents each relative to the carboxyl groups of the polyamic acid, and a dehydration and cyclization reaction was carried out at 80°C for 4 hours. After the dehydration and cyclization reaction, NMP was added and the solution was further concentrated to obtain a solution containing 20% ​​by mass of polyimide with an imidization rate of 64% (referred to as polymer (P-1)). A small amount of this solution was taken, and NMP was added to make a 10% by mass solution. The measured viscosity of this solution was 44.5 mPa·s.

[0087] [Synthesis examples 5-9, 12, 23, 25] Polymerization was carried out in the same manner as in Synthesis Example 1, except that the types and amounts of tetracarboxylic dianhydride and diamine compounds used for polymerization were changed as shown in Table 1, and solutions containing polymers (P-5) to (P-9), polymer (P-12), polymer (P-23), and polymer (P-25), which are polyimides, were obtained.

[0088] 2. Synthesis of polyamic acids [Synthesis Example 2] A solution containing 20% ​​by mass of polyamic acid (referred to as polymer (P-2)) was obtained by dissolving 50 mole parts of compound (T-1), 30 mole parts of compound (T-2), and 20 mole parts of compound (T-5) as tetracarboxylic dianhydrides, and 30 mole parts of compound (D-1), 30 mole parts of compound (D-3), 10 mole parts of compound (D-5), and 30 mole parts of compound (D-14) as diamine compounds in NMP and reacting at 40°C for 24 hours. A small amount of this solution was taken, and NMP was added to make a 10% by mass solution. The viscosity of the solution measured was 50.4 mPa·s.

[0089] [Synthesis examples 3, 4, 10, 11, 13-22, 24] Polymerization was carried out in the same manner as in Synthesis Example 2, except that the types and amounts of tetracarboxylic dianhydride and diamine compounds used for polymerization were changed as shown in Table 1, and solutions containing polymers (P-3), (P-4), (P-10), (P-11), (P-13) to (P-22), and (P-24), which are polyamic acids, were obtained.

[0090] Polymerization was carried out by adjusting the molar ratio of diamine to tetracarboxylic dianhydride (diamine / tetracarboxylic dianhydride) to 0.95-1.00 so that the viscosity of the NMP solution with a polymer concentration of 10% by mass was 40-60 mPa·s. In Table 1, the values ​​for tetracarboxylic dianhydride represent the proportion (moles) of each compound relative to 100 moles of the total amount of tetracarboxylic dianhydride used in the synthesis. The values ​​for diamine represent the proportion (moles) of each compound relative to 100 moles of the total amount of diamine used in the synthesis.

[0091] [Table 1]

[0092] 3. Synthesis of addition polymers [Synthesis Example 26] Under nitrogen, 10 moles of compound (M-1), 5 moles of compound (M-3), 30 moles of compound (M-4), 45 moles of compound (M-5), and 10 moles of compound (M-6) as polymerization monomers, 2 moles of 2,2'-azobis(2,4-dimethylvaleronitrile) as a radical polymerization initiator, and 50 mL of tetrahydrofuran as a solvent were added to a 100 mL two-necked flask, and polymerization was carried out at 70°C for 5 hours. After reprecipitation in methanol, the precipitate was filtered and vacuum-dried at room temperature for 8 hours to obtain a styrene-maleimide copolymer (referred to as polymer (PM-1)). The weight-average molecular weight Mw, measured in polystyrene equivalent by GPC, was 30,000, and the molecular weight distribution Mw / Mn was 2.

[0093] [Synthesis Example 27] Polymerization was carried out in the same manner as in Synthesis Example 26, except that the type and amount of monomers used for polymerization were changed as shown in Table 2, to obtain polymer (PM-2), which is a styrene-maleimide copolymer.

[0094] [Table 2]

[0095] 4. Synthesis of polyorganosiloxanes [Synthesis Example 28] 90.0 g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 500 g of methyl isobutyl ketone, and 10.0 g of triethylamine were charged into a 1000 mL three-necked flask and mixed at room temperature. Then, 100 g of deionized water was added dropwise from a dropping funnel over 30 minutes, and the reaction was carried out at 80°C for 6 hours while mixing under reflux. After the reaction was complete, the organic layer was removed and washed with 0.2% by mass aqueous solution of ammonium nitrate until the water after washing was neutral, and then the solvent and water were removed under reduced pressure. An appropriate amount of methyl isobutyl ketone was added to obtain a 50% by mass solution of the polymer (ESSQ-1), which is a polyorganosiloxane having epoxy groups. In a 500 mL three-necked flask, 6.28 g of compound (CA-1) (20 mol% relative to the amount of epoxy groups in polymer (ESSQ-1)), 3.44 g of compound (CA-2) (10 mol% relative to the amount of epoxy groups in polymer (ESSQ-1)), 2.00 g of tetrabutylammonium bromide, 80 g of a solution containing polymer (ESSQ-1), and 239 g of methyl isobutyl ketone were added, and the mixture was stirred at 90°C for 18 hours. After cooling to room temperature, the mixture was subjected to 10 separate washings with distilled water. The organic layer was then collected, concentrated and diluted twice using a rotary evaporator, and then adjusted using NMP to a solid content concentration of 10% by mass to obtain an NMP solution of polymer (PS-1).

[0096] <Preparation and evaluation of liquid crystal alignment agents> [Example 1: PSA-type liquid crystal display element] (1) Preparation of liquid crystal alignment agent (AL-1) To a solution containing 95 parts by mass of polymer (P-1) obtained in Synthesis Example 1, 5 parts by mass of polymer (PM-1) obtained in Synthesis Example 26, 10 parts by mass of compound (a-1), and NMP and butyl cellosolve (BC) as solvents were added to prepare a solution with a solvent composition of NMP / BC = 50 / 50 (mass ratio) and a solid content concentration of 4.0% by mass. Liquid crystal alignment agent (AL-1) was prepared by filtering this solution through a pore size 0.2 μm filter.

[0097] (2) Preparation of liquid crystal composition To 10 g of nematic liquid crystal (Merck, MLC-6608), 5% by mass of a liquid crystalline compound represented by the following formula (L1-1) and 0.3% by mass of a photopolymerizable compound represented by the following formula (L2-1) were added and mixed to obtain liquid crystal composition LC1. [ka]

[0098] (3) Manufacturing of PSA type liquid crystal display elements The liquid crystal alignment agent (AL-1) prepared above was applied to each electrode surface of two glass substrates, each having a conductive film consisting of slit-patterned ITO electrodes, using a liquid crystal alignment film printing machine (manufactured by Nippon Printing Co., Ltd.). The film was then heated on an 80°C hot plate for 2 minutes (pre-bake) to remove the solvent, and then heated on a 230°C hot plate for 10 minutes (post-bake) to form a coating with an average thickness of 0.06 μm. These coatings were ultrasonically cleaned in ultrapure water for 1 minute, and then dried in a 100°C clean oven for 10 minutes to obtain a pair (2 substrates) with liquid crystal alignment films. The electrode patterns used were the same as those used in PSA mode. Next, an epoxy resin adhesive containing aluminum oxide spheres with a diameter of 5.5 μm was applied to the outer edge of the surface of one of the pair of substrates having a liquid crystal alignment film. Then, the two substrates were overlapped and pressed together so that the liquid crystal alignment film surfaces faced each other, and the adhesive was cured. Next, the liquid crystal composition LC1 prepared above was filled between the pair of substrates through the liquid crystal injection port, and the liquid crystal injection port was sealed with an acrylic photocurable adhesive to manufacture a liquid crystal cell. Subsequently, an AC voltage of 10V at a frequency of 60Hz was applied between the conductive films of the liquid crystal cell, and while the liquid crystal was in operation, an ultraviolet irradiation device using a metal halide lamp as the light source was used to irradiate it with an intensity of 100,000 J / m². 2 Ultraviolet light was irradiated at the specified dose. This dose was measured using a light meter that measures at a wavelength of 365 nm. Subsequently, a PSA-type liquid crystal display element was manufactured by bonding polarizing plates to both outer surfaces of the substrate so that their polarization directions were perpendicular to each other and that they formed a 45° angle with the projection direction of the ultraviolet light axis of the liquid crystal alignment film onto the substrate surface.

[0099] (4) Evaluation of seal adhesion A liquid crystal alignment agent (AL-1) was applied to a glass substrate using a spinner, pre-baked on an 80°C hot plate for 2 minutes, and then heated in a 230°C oven with nitrogen purging for 30 minutes (post-bake) to form a coating with an average thickness of 0.10 μm. Two glass substrates with the coating were prepared by repeating the same procedure. On the coating of one glass substrate, an ODF sealant (Sekisui Chemical Co., Ltd., S-WB42) was applied to a width of 1 mm, and the other glass substrate was bonded so that the coating and the ODF sealant were in contact. After that, a metal halide lamp was used to irradiate the substrate at 30,000 J / m². 2 After irradiating with light (equivalent to 365 nm), the sample was heated in a 120°C oven for 1 hour. Then, the seal adhesion was evaluated by measuring the adhesion force using an Imada Seisakusho tensile and compression testing machine (model number: SDWS-0201-100SL). The evaluation was based on an adhesion force of 180 N / cm². 2 If the result is above this, it is classified as "Excellent (◎)", 160 N / cm 2 More than 180N / cm 2If the value is less than 140 N / cm², it is considered "Good (○)". 2 More than 160N / cm 2 If it is less than 140 N / cm², it is marked as "Acceptable (△)". 2 A result below the specified value was classified as "Poor (×)". As a result, in this example, it received an excellent (◎) rating.

[0100] (5) Evaluation of the refractive index of the film A liquid crystal alignment agent (AL-1) was spin-coated onto a silicon wafer, pre-baked on an 80°C hot plate for 2 minutes, and then heated in a 230°C oven with nitrogen purging for 30 minutes (post-bake) to form a coating with an average thickness of 0.10 μm. Next, the refractive index at wavelengths of 400 to 800 nm was measured using a spectroscopic ellipsometer (SE-2000, Semilab) and fitting with the CAUCHY model. The refractive index at a wavelength of 550 nm was also evaluated. A refractive index of 1.635 or higher was rated as "Excellent (◎)", a refractive index of 1.630 or higher and less than 1.635 was rated as "Good (○)", a refractive index of 1.625 or higher and less than 1.630 was rated as "Acceptable (△)", and a refractive index of less than 1.625 was rated as "Poor (×)". As a result, this example received an evaluation of Excellent (◎).

[0101] (6) Evaluation of afterimage characteristics The PSA-type liquid crystal display element obtained in (3) above was driven with an AC voltage of 4.5V to set the brightness difference between any two pixels to 0. Then, while driving with AC 4.5V, a DC voltage of 1V was applied to only one of the pixels for 20 minutes to accumulate charge. When the application of DC 1V was terminated and the drive was returned to AC 4.5V only, a brightness difference was created between the two pixels due to the accumulated charge. By observing the change in this brightness difference over time, the relaxation time during the decay process of the residual DC value was calculated. A relaxation time of less than 10 seconds was judged as "Excellent (◎)", a relaxation time of 10 seconds or more but less than 20 seconds was judged as "Good (○)", a relaxation time of 20 seconds or more but less than 30 seconds was judged as "Acceptable (△)", and a relaxation time of 30 seconds or more was judged as "Poor". As a result, in this embodiment, the evaluation was Excellent (◎).

[0102] (7) Evaluation of applicability (in-plane uniformity) The liquid crystal alignment agent (AL-1) prepared in (1) above was stored in a freezer at -15°C for 7 days. After thawing the liquid crystal alignment agent to room temperature, the coatability (in-plane uniformity) was evaluated using the thawed liquid crystal alignment agent. The evaluation was performed as follows. After thawing, the liquid crystal alignment agent was continuously coated onto an ITO substrate using a JET-CM continuous inkjet printer (manufactured by Kishu Giken Kogyo Co., Ltd.) at a volume that resulted in a film thickness of 0.1 μm after drying. The time required from the start of application of the liquid crystal alignment agent to the completion of coating the entire substrate and baking was 10 minutes. The resulting alignment-coated substrate was pre-baked on a hot plate at 80°C for 2 minutes, and then post-baked at 230°C for 30 minutes in a clean oven under a nitrogen atmosphere. After that, the peripheral and central parts of the liquid crystal alignment film were observed with a 20x microscope. At this time, if the total number of uneven and repelled areas was 0, it was judged as "Excellent (◎)", if the total number of uneven and repelled areas was 1 or more but less than 3, it was judged as "Good (○)", if the total number of uneven and repelled areas was 3 or more but less than 5, it was judged as "Acceptable (△)", and if the total number of uneven and repelled areas was 5 or more, it was judged as "Poor (×)". As a result, this embodiment received an excellent (◎) rating.

[0103] [Examples 2-4, 7, 11-31 and Comparative Examples 1-7] Except for the changes in the compound composition shown in Tables 3 and 4, the liquid crystal alignment agents (AL-2) to (AL-4), (AL-7), (AL-11) to (AL-31), and (AR-1) to (AR-7) were prepared with the same solvent composition and solid content concentration as in Example 1. Furthermore, using each liquid crystal alignment agent, the seal adhesion, refractive index of the film, and in-plane uniformity were evaluated in the same manner as in Example 1, and PSA-type liquid crystal display elements were manufactured to evaluate the afterimage characteristics. The evaluation results are shown in Tables 3 and 4. In Tables 3 and 4, blank spaces indicate that the compound was not used.

[0104] [Example 5: Optical vertical liquid crystal display element] (1) Preparation of liquid crystal alignment agent, and evaluation of seal adhesion, refractive index and in-plane uniformity of the film. Except for the changes in the compound composition shown in Table 3, the liquid crystal alignment agent (AL-5) was prepared with the same solvent composition and solid content concentration as in Example 1. Furthermore, the seal adhesion, refractive index of the film, and in-plane uniformity were evaluated using the liquid crystal alignment agent (AL-5) in the same manner as in Example 1. The evaluation results are shown in Table 3.

[0105] (2) Manufacturing of vertical optical liquid crystal display elements The liquid crystal alignment agent (AL-5) prepared above was applied to the transparent electrode surface of a glass substrate with a transparent electrode made of ITO film using a spinner, and pre-baked on a hot plate at 80°C for 1 minute. Then, it was heated in an oven with nitrogen purging at 230°C for 1 hour to form a coating with a thickness of 0.1 μm. Next, the surface of this coating was exposed to polarized ultraviolet light containing a 313 nm emission line at 1,000 J / m using a Hg-Xe lamp and a Gran-Taylor prism. 2 The substrate was irradiated from a direction tilted 40° from the substrate normal to impart liquid crystal alignment capability. The same operation was repeated to create a pair (2 substrates) of substrates with a liquid crystal alignment film. An epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was screen printed onto the outer periphery of one of the substrates having a liquid crystal alignment film. Then, the liquid crystal alignment film surfaces of the pair of substrates were placed facing each other, and they were pressed together so that the projection direction of the ultraviolet optical axis of each substrate onto the substrate surface was opposite parallel. The adhesive was then heat-cured at 150°C for 1 hour. Next, negative liquid crystal (Merck MLC-6608) was filled into the gap between the substrates through the liquid crystal injection port, and the liquid crystal injection port was sealed with epoxy adhesive. Furthermore, to remove the flow orientation during liquid crystal injection, it was heated at 130°C and then slowly cooled to room temperature. Next, polarizing plates were bonded to both outer surfaces of the substrates so that their polarization directions were perpendicular to each other and formed a 45° angle with the projection direction of the ultraviolet optical axis of the liquid crystal alignment film onto the substrate surface, thereby manufacturing a vertical-optical liquid crystal display element.

[0106] (3) Evaluation of afterimage characteristics The afterimage characteristics were evaluated using the optically perpendicular liquid crystal display element manufactured as described above, in the same manner as in Example 1. As a result, this example received an excellent (◎) rating.

[0107] [Example 6] Except for the change in the compound composition shown in Table 3, the liquid crystal alignment agent (AL-6) was prepared with the same solvent composition and solid content concentration as in Example 1. Furthermore, using the liquid crystal alignment agent (AL-6), the seal adhesion, film refractive index, and in-plane uniformity were evaluated in the same manner as in Example 1. Additionally, a vertical-optical liquid crystal display element was manufactured in the same manner as in Example 5, and the afterimage characteristics were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3.

[0108] [Example 8: Rubbing-type liquid crystal display element] (1) Preparation of liquid crystal alignment agent, and evaluation of seal adhesion, refractive index and in-plane uniformity of the film. Except for the changes in the compound composition shown in Table 3, the liquid crystal alignment agent (AL-8) was prepared with the same solvent composition and solid content concentration as in Example 1. Furthermore, the seal adhesion, refractive index of the film, and in-plane uniformity were evaluated using the liquid crystal alignment agent (AL-8) in the same manner as in Example 1. The evaluation results are shown in Table 3.

[0109] (2) Manufacturing of rubbing-type liquid crystal display elements A glass substrate (referred to as the first substrate) was prepared, in which a flat electrode (bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) were laminated on one side in this order, and a glass substrate (referred to as the second substrate) was prepared without electrodes. Next, a liquid crystal alignment agent (AL-8) was applied to the electrode-forming surface of the first substrate and one side of the second substrate using a spinner, and heated on a 110°C hot plate for 3 minutes (pre-bake). After that, it was dried for 30 minutes in a 230°C oven with nitrogen purging (post-bake) to form a coating with an average film thickness of 0.1 μm. Next, the surface of the coating was rubbed using a rubbing machine with a roll wrapped in rayon cloth at a roll rotation speed of 1,000 rpm, a stage movement speed of 3 cm / second, and a pile insertion length of 0.3 mm. After that, it was ultrasonically cleaned in ultrapure water for 1 minute, and then dried in a 100°C clean oven for 10 minutes to obtain a pair of substrates having a liquid crystal alignment film. Next, for a pair of substrates having a liquid crystal alignment film, an epoxy resin adhesive containing 3.5 μm diameter aluminum oxide spheres was screen-printed and applied, leaving a liquid crystal injection port at the edge of the surface where the liquid crystal alignment film was formed. Then, the substrates were stacked and pressed together, and the adhesive was heat-cured at 150°C for 1 hour. Next, negative liquid crystal (Merck MLC-6608) was filled into the gap between the pair of substrates through the liquid crystal injection port, and the liquid crystal injection port was sealed with epoxy adhesive. Furthermore, to eliminate the flow orientation during liquid crystal injection, this was heated to 120°C and then slowly cooled to room temperature to manufacture a liquid crystal cell. When stacking the pair of substrates, the rubbing directions of each substrate were made antiparallel. Next, polarizing plates were bonded to both outer surfaces of the substrate in the liquid crystal cell to obtain a rubbing-type liquid crystal display element.

[0110] (3) Evaluation of afterimage characteristics The afterimage characteristics were evaluated using the rubbing-type liquid crystal display element manufactured as described above, in the same manner as in Example 1. As a result, this example received an excellent (◎) rating.

[0111] [Example 32] Except for the changes in the compound composition shown in Table 4, the liquid crystal alignment agent (AL-32) was prepared with the same solvent composition and solid content concentration as in Example 1. Furthermore, using the liquid crystal alignment agent (AL-32), the seal adhesion, film refractive index, and in-plane uniformity were evaluated in the same manner as in Example 1. Additionally, a rubbing-type liquid crystal display element was manufactured in the same manner as in Example 8, and the afterimage characteristics were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

[0112] [Example 10: Optical horizontal type liquid crystal display element] (1) Preparation of liquid crystal alignment agent, and evaluation of seal adhesion, refractive index and in-plane uniformity of the film. Except for the changes in the compound composition shown in Table 3, the liquid crystal alignment agent (AL-10) was prepared with the same solvent composition and solid content concentration as in Example 1. Furthermore, the seal adhesion, refractive index of the film, and in-plane uniformity were evaluated using the liquid crystal alignment agent (AL-10) in the same manner as in Example 1. The evaluation results are shown in Table 3.

[0113] (2) Manufacturing of horizontal optical liquid crystal display elements A first substrate and a second substrate were prepared in the same manner as in Example 8. Next, a liquid crystal alignment agent (AL-10) was applied to the electrode formation surface of the first substrate and one substrate surface of the second substrate using a spinner, and heated on an 80°C hot plate for 1 minute (pre-bake). After that, drying was performed for 30 minutes in a 230°C oven with nitrogen purging (post-bake) to form a coating film with an average thickness of 0.1 μm. The obtained coating film was exposed to 1,000 J / m of ultraviolet light containing linearly polarized 254 nm emission lines using an Hg-Xe lamp. 2 The substrate was irradiated from the direction normal to the substrate to perform photoalignment treatment. The irradiation dose was measured using a light meter that measures at a wavelength of 254 nm. Next, the photoaligned coating was heat-treated by heating it in a clean oven at 230°C for 30 minutes to form a liquid crystal alignment film. Next, on one of the pair of substrates on which the liquid crystal alignment film was formed, an epoxy resin adhesive containing aluminum oxide spheres with a diameter of 3.5 μm was screen printed onto the outer edge of the surface with the liquid crystal alignment film. Then, the substrates were stacked and pressed together so that the projection direction of the polarization axis onto the substrate surface during light irradiation was antiparallel, and the adhesive was heat-cured at 150°C for 1 hour. Subsequently, negative liquid crystal (Merck, MLC-6608) was filled between the pair of substrates through the liquid crystal injection port, and the liquid crystal injection port was sealed with epoxy adhesive to obtain a liquid crystal cell. Furthermore, to remove the flow orientation during liquid crystal injection, it was heated at 120°C and then slowly cooled to room temperature. After that, polarizing plates were bonded to both outer surfaces of the substrate in the liquid crystal cell to obtain a liquid crystal display element. The above series of operations was performed with a post-bake UV irradiation dose of 100 to 10,000 J / m². 2 By modifying each element within the specified range, three or more liquid crystal display elements with different UV irradiation levels were manufactured. The liquid crystal display element exhibiting the best orientation characteristics (optimal exposure) was used to evaluate the afterimage characteristics in the same manner as in Example 1. As a result, this example received an excellent (◎) rating.

[0114] [Example 33] Except for the changes in the compound composition shown in Table 4, the liquid crystal alignment agent (AL-33) was prepared with the same solvent composition and solid content concentration as in Example 1. Furthermore, using the liquid crystal alignment agent (AL-33), the seal adhesion, film refractive index, and in-plane uniformity were evaluated in the same manner as in Example 1. Additionally, a horizontal optical liquid crystal display element was manufactured in the same manner as in Example 10, and the afterimage characteristics were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

[0115] [Table 3]

[0116] [Table 4]

[0117] In addition, the "Overall Evaluation" in Tables 3 and 4 was evaluated according to the following criteria: "◎" if all four evaluation items received the highest evaluation; "○" if there were no poor (×) or good (△) evaluation results among the four evaluation items, but one or more evaluation items did not receive the highest evaluation; "△" if there were no poor (×) evaluation results among the four evaluation items, but one or more evaluation items received a good (△) evaluation; and "×" if any one of the four evaluation items received a poor (×) evaluation.

[0118] As shown in Tables 3 and 4, the liquid crystal alignment agents of Examples 1 to 33 all exhibited excellent (◎), good (○), or acceptable (△) properties in terms of seal adhesion, film refractive index, afterimage characteristics, and coatability (in-plane uniformity), demonstrating a good balance of various characteristics. In contrast, Comparative Examples 1, 3-7, which did not contain compound (B), were unsatisfactory (×) in one or more of the following evaluations: seal adhesion, film refractive index, afterimage characteristics, and coatability (in-plane uniformity). Furthermore, Comparative Example 2, which contained 60 parts by mass of compound (B), was unsatisfactory (×) in all three evaluations: seal adhesion, afterimage characteristics, and coatability.

[0119] From the above results, it has become clear that by using a liquid crystal alignment agent containing a predetermined amount of compound (B) together with polymer (A), it is possible to form a liquid crystal alignment film with less in-plane unevenness and repulsion, excellent seal adhesion, and a high refractive index, and moreover, a liquid crystal element that produces less afterimage.

Claims

1. The following polymer component is included: (A) polymer and (B) compound. The content of compound (B) is 50 parts by mass or less per 100 parts by mass of the polymer component. A liquid crystal alignment agent wherein the polymer component further comprises a polymer different from the polymer (A) above. (A) Polymer: at least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, and * １ -NR １ -* １ *, １ -NR １ R ２ *, １ -NR １ -CO-* １ *, １ -NR １ -CO-NR ３ -* １ and at least one selected from the group consisting of a nitrogen-containing heterocyclic group, which is a nitrogen-containing group different from the amino group participating in polymerization (however, R １ and R ３ are each independently a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a monovalent thermally dissociable group. R ２ is a monovalent hydrocarbon group having 1 to 10 carbon atoms or a monovalent thermally dissociable group. "* １ " represents a bond to a carbon atom.) A polymer containing 5 mol% or more of a structural unit (D) derived from a diamine having such a group with respect to the total amount of the structural units derived from the diamine compound constituting the (A) polymer (B) Compounds: Compounds having at least one selected from the group consisting of a naphthalene ring structure, a fluorene ring structure, a carbazole ring structure, and a triazine ring structure, and a crosslinkable group, and different from the polymer (A) (except for compounds having a triazine ring structure and a (meth)acryloyloxy group, and having one (meth)acryloyloxy group).

2. The liquid crystal alignment agent according to claim 1, wherein the polymer (A) comprises structural units derived from an aromatic tetracarboxylic acid derivative.

3. The liquid crystal alignment agent according to claim 2, wherein the aromatic tetracarboxylic acid derivative comprises at least one selected from the group consisting of pyromellitic acid derivatives and biphenyltetracarboxylic acid derivatives.

4. The liquid crystal alignment agent according to claim 1, wherein at least one selected from the group consisting of the polymer (A) and polymers different from the polymer (A) comprises a structural unit derived from a diamine having a carboxyl group (excluding structural unit (D)).

5. The liquid crystal alignment agent according to claim 1, wherein the structural unit (D) has the nitrogen-containing group in the side chain of the polymer.

6. The aforementioned nitrogen-containing group is * １ -NR １ - * １ , * １ -NR １ -CO-* １ , * １ -NR １ -CO-NR ３ - * １ and at least one selected from the group consisting of nitrogen-containing heterocyclic groups, The liquid crystal alignment agent according to claim 1, wherein the structural unit (D) has the nitrogen-containing group in the main chain of the polymer.

7. The liquid crystal alignment agent according to claim 1, wherein the crosslinkable group of compound (B) is at least one selected from the group consisting of a methylol group, an alkoxymethyl group, a hydroxyalkylamide group, an alkoxysilyl group, an oxyranyl group, an oxetanyl group, and a carbon-carbon unsaturated bond-containing group.

8. The liquid crystal alignment agent according to claim 1, wherein the content of compound (B) is 0.1 parts by mass or more and 40 parts by mass or less per 100 parts by mass of the polymer component.

9. The liquid crystal alignment agent according to claim 1, wherein the content of the structural unit (D) in the polymer (A) is 85 mol% or less relative to the total amount of structural units derived from the diamine.

10. The liquid crystal alignment agent according to claim 1, wherein the polymer different from polymer (A) is at least one selected from the group consisting of polyamic acid, polyamic acid ester, polyimide, polyorganosiloxane, and addition polymer.

11. A liquid crystal alignment film formed using the liquid crystal alignment agent described in any one of claims 1 to 10.

12. A liquid crystal element comprising the liquid crystal alignment film described in claim 11.

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