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

Abstract

This invention provides a liquid crystal alignment agent that can form a liquid crystal alignment film with high mechanical strength and can obtain a liquid crystal element with low light intensity and low transmittance, which is less prone to image retention caused by the accumulation of residual charge. The liquid crystal alignment agent contains a polymer having structural units derived from the compound represented by formula (1). In formula (1), Ar 1 is a divalent aromatic cyclic group. X 1 is a single bond, -O-, -S- or -NR 1-. Ar 2, Ar 3 and Y 1 satisfy specific requirements. In the case that X 1 is a single bond, Y 1 is bonded to Ar 1 through a carbon atom. (i) Ar 2 is a divalent aromatic cyclic group, Ar 3 is a monovalent aromatic cyclic group, and Y 1 is a divalent organic group with more than 1 carbon atom. (ii) Ar 2 and Ar 3 represent nitrogen-containing aromatic fused ring structures. Y 1 is a divalent organic group with more than 1 carbon atom. (iii) Ar 2 is a divalent aromatic cyclic group. Ar3 and Y1 are divalent groups containing nitrogen-containing aromatic fused ring structures.

Description

[Technical Field]

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

[0002] Liquid crystal elements are used in a wide range of applications, from relatively large display devices such as LCD TVs or information displays to small display devices such as smartphones. The performance of a liquid crystal element is determined by various characteristics such as the alignment or pretilt angle of the liquid crystal and the voltage holding rate. In order to improve the performance of liquid crystal elements, in addition to improving the liquid crystal material, improvements have also been made to the liquid crystal alignment film used to align the liquid crystal in a certain direction.

[0003] In liquid crystal elements, when charge accumulates within the liquid crystal cells, it is sometimes perceived by the observer as a residual image (direct current (DC) image), which degrades the display quality of the liquid crystal element. Therefore, as one of the required characteristics of liquid crystal alignment films, low charge accumulation is one such characteristic.

[0004] Therefore, various techniques for suppressing charge accumulation within liquid crystal cells and improving the display quality of liquid crystal elements have been proposed in the past (for example, see Patent Document 1). Patent Document 1 discloses a method for reducing accumulated charge by making a liquid crystal alignment agent contain a polyamide, specifically a polyamide obtained by reacting a diamine compound containing a nitrogen-containing diamine, such as N4,N4'-bis(4-aminophenyl)-benzidine, with a tetracarboxylic acid dianhydride. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2008-107811 [Summary of the Invention]

[0006] [Problem to be Solved by the Invention] In recent years, with the increasing precision of liquid crystal elements, the quality requirements for liquid crystal elements have become more stringent. Therefore, it is also required to minimize the charge accumulated in the liquid crystal element due to the application of voltage to reduce image retention, or to achieve high transmittance of the liquid crystal element. Furthermore, when considering the application of rubbing methods, or improving liquid crystal alignment and voltage retention rate, and suppressing yield reduction, it is required that the organic film formed using liquid crystal alignment agents has sufficiently high strength.

[0007] In the manufacturing process of liquid crystal alignment films or liquid crystal elements, sometimes polymers or other decomposition products are generated by applying a heat or light load to the liquid crystal alignment film or the organic film that becomes the liquid crystal alignment film. Furthermore, the generation of these thermal or photodecomposition products can sometimes result in display defects (bright spots) in the obtained liquid crystal element. In order to achieve further high quality in liquid crystal elements, it is necessary to suppress the generation of these bright spots.

[0008] The purpose of this invention is to provide a liquid crystal alignment agent that can form a liquid crystal alignment film with high mechanical strength, and can obtain a liquid crystal element that is less prone to image retention caused by the accumulation of residual charge, has fewer bright spots, and has high transmittance. [Technical Means for Solving the Problem]

[0009] The inventors have conducted diligent research and discovered that the aforementioned problem can be solved by using a diamine having a specific structure, thus completing the present invention. Specifically, the present invention can provide the following means.

[0010] <1> A liquid crystal alignment agent comprising a polymer (P) having structural units derived from a compound represented by the following formula (1). [Chemistry 1] (In formula (1), Ar 1 is a divalent aromatic cyclic group; X 1 is a single bond, -O-, -S- or -NR 1-; R 1 is a hydrogen atom, an alkyl group with 1 to 3 carbon atoms, or a thermally detachable group; Ar 2, Ar 3 and Y 1 satisfy the following requirements (i), (ii) or (iii); wherein, in the case that X 1 is a single bond, Y 1 is bonded to Ar 1 through a carbon atom; (i) Ar 2 is a divalent aromatic cyclic group; Ar 3 is a monovalent aromatic cyclic group; Y 1 is a divalent organic group with 1 or more carbon atoms; (ii) Ar 2 and Ar 3 represent nitrogen-containing aromatic fused ring structures formed together with nitrogen atoms bonded to Ar 2 and Ar 3; Y 1 is a divalent organic group with 1 or more carbon atoms; (iii) Ar 2 is a divalent aromatic cyclic group; Ar 3 and Y 1 contain nitrogen atoms bonded together with Ar 3 and Y 1. (a divalent group of a nitrogen-containing aromatic fused ring structure formed by the nitrogen atoms bonded together)

[0011] <2> A liquid crystal alignment film, formed using the liquid crystal alignment agent of <1>. <3> A liquid crystal element comprising the liquid crystal alignment film of <2>. [Effects of the Invention]

[0012] The liquid crystal alignment agent of the present invention can form a liquid crystal alignment film with high mechanical strength, and can obtain a liquid crystal element with high transmittance that is not prone to image retention and bright spots.

Implementation Method

[0013] Liquid Crystal Alignment Agent Hereinafter, the components contained in the liquid crystal alignment agent disclosed herein and other components that may be arbitrarily added as needed will be described.

[0014] Furthermore, in this specification, the term "hydrocarbon group" includes chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. "Chain hydrocarbon group" refers to a straight-chain hydrocarbon group or branched hydrocarbon group whose main chain does not contain a ring structure and is composed only of a chain structure. The chain hydrocarbon group can be saturated or unsaturated. "Alicyclic hydrocarbon group" refers to a hydrocarbon group that contains only the structure of an alicyclic hydrocarbon as a ring structure and does not contain an aromatic ring structure. The alicyclic hydrocarbon group does not necessarily need to contain only the structure of an alicyclic hydrocarbon, but may also include groups with a chain structure in a portion thereof. "Aromatic hydrocarbon group" refers to a hydrocarbon group that contains an aromatic ring structure as a ring structure. The aromatic hydrocarbon group does not necessarily need to contain only the aromatic ring structure, but may also contain a chain structure or an alicyclic hydrocarbon structure in a portion thereof. "Aromatic ring" includes aromatic hydrocarbon rings and aromatic heterocycles. "Organic group" refers to a group of atoms formed by removing any hydrogen atom from a carbon-containing compound (i.e., an organic compound).

[0015] The "main chain" of a polymer refers to the portion of the polymer containing the longest atomic chain, the "stem". The "stem" portion may contain ring structures. For example, "having a specific structure in the main chain" means that the specific structure constitutes part of the main chain. The term "side chain" refers to a portion that branches off from the "stem" of the polymer. "Tetracarboxylic acid derivative" means that it includes tetracarboxylic dianhydride, tetracarboxylic acid diester, and tetracarboxylic acid diester dihalides.

[0016] The liquid crystal alignment agent disclosed herein contains a polymer (P) having structural units derived from a compound represented by the following formula (1) (hereinafter also referred to as "specific diamine"). [Chemistry 2] (In formula (1), Ar 1 is a divalent aromatic cyclic group; X 1 is a single bond, -O-, -S- or -NR 1-; R 1 is a hydrogen atom, an alkyl group with 1 to 3 carbon atoms, or a thermally detachable group; Ar 2, Ar 3 and Y 1 satisfy the following requirements (i), (ii) or (iii); wherein, in the case that X 1 is a single bond, Y 1 is bonded to Ar 1 through a carbon atom; (i) Ar 2 is a divalent aromatic cyclic group; Ar 3 is a monovalent aromatic cyclic group; Y 1 is a divalent organic group with 1 or more carbon atoms; (ii) Ar 2 and Ar 3 represent nitrogen-containing aromatic fused ring structures formed by mutual bonding and together with nitrogen atoms bonded to Ar 2 and Ar 3; Y 1 is a divalent organic group with 1 or more carbon atoms; (iii) Ar 2 is a divalent aromatic cyclic group; Ar 3 and Y 1 contain mutual bonding and together with Ar 3 and Y (a divalent group of a nitrogen-containing aromatic fused ring structure formed by the nitrogen atoms bonded together)

[0017] Hereinafter, the polymer (P) and any other components that may be blended will be described in detail. In addition, unless otherwise specified, each component may be used alone or in combination of two or more.

[0018] <Polymer (P)> In the formula (1), when Ar 2, Ar 3 and Y 1 satisfy the requirement (i), the divalent aromatic ring group represented by Ar 1 or Ar 2 is a group formed by removing two arbitrary hydrogen atoms from the ring portion of the aromatic ring. Examples of aromatic rings include: aromatic hydrocarbon rings such as benzene ring, naphthalene ring, anthracene ring, and biphenyl ring; nitrogen-containing aromatic heterocycles such as pyrrole ring, imidazole ring, pyrazole ring, pyridine ring, pyrimidine ring, pyridazine ring, pyrazine ring, quinoline ring, isoquinoline ring, benzimidazole ring, carbazole ring, and acridine ring. Among these, Ar 1 and Ar 2 are preferably groups having a structure formed by removing two hydrogen atoms from the ring portion of the benzene ring or pyridine ring, and more preferably substituted or unsubstituted phenyl groups. Substituents may also be introduced independently of the primary amine base into the aromatic ring group represented by Ar 1 and Ar 2. Examples of substituents include alkyl groups having 1 to 3 carbon atoms, alkoxy groups having 1 to 3 carbon atoms, and halogen atoms.

[0019] The monovalent aromatic ring group represented by Ar 3 is a group formed by removing an arbitrary hydrogen atom from the ring portion of an aromatic ring. Specific examples of aromatic rings may be listed as groups identical to those exemplified in the descriptions of the divalent aromatic ring groups represented by Ar 1 and Ar 2. Ar 3 is preferably a group having a structure formed by removing a hydrogen atom from the ring portion of a benzene ring, naphthalene ring, or pyridine ring, and more preferably a substituted or unsubstituted phenyl group. Examples of substituents present in the ring portion of Ar 3 include: alkyl groups having 1 to 3 carbon atoms, alkoxy groups having 1 to 3 carbon atoms, halogen atoms, etc.

[0020] When R1 is an alkyl group having 1 to 3 carbon atoms, the alkyl group can be linear or branched. The thermally releasable group is a group that is desorbed by heat and generates hydrogen atoms. Examples of R1 that can be thermally releasable include: groups containing an aminocarbamate structure, groups containing an amide structure, groups containing an imine structure, groups containing a sulfonamide structure, etc. Among these, groups containing an aminocarbamate structure are preferred for their high thermal releasability. Specific examples include: tributoxycarbonyl, benzyloxycarbonyl, 1,1-dimethyl-2-haloethyloxycarbonyl, allyloxycarbonyl, 2-(trimethylsilyl)ethoxycarbonyl, 9-fluorenylmethyloxycarbonyl, etc. Among these, tributoxycarbonyl (Boc group) is particularly preferred for its excellent thermal releasability and ability to reduce the amount of deprotected portion remaining in the film.

[0021] In terms of obtaining a liquid crystal alignment film with high mechanical strength, R1 is preferably a hydrogen atom, a methyl group or a thermally detachable group, and more preferably a hydrogen atom.

[0022] As represented by Y 1, examples include: divalent hydrocarbon groups with 1 to 20 carbon atoms; divalent hydrocarbon groups with 1 to 20 carbon atoms formed by replacing any of the extended methyl groups with -O-, -S-, -CO-, -COO-, -OCO-, -NR-, -NR 10CO-, -CONR 10-, -NR 10COO-, -OCONR 10-, -NR 10-CO-NR 11-, etc. (where R 10 and R 11 are independently hydrogen atoms, monovalent hydrocarbon groups with 1 to 10 carbon atoms, or thermally detachable groups, respectively; the same applies below); groups with heterocyclic structures, etc.

[0023] When Y1 is a divalent hydrocarbon group with 1 to 20 carbon atoms, examples of such hydrocarbon groups include: chain hydrocarbon groups with 1 to 20 carbon atoms, alicyclic hydrocarbon groups with 3 to 20 carbon atoms, and aromatic hydrocarbon groups with 6 to 20 carbon atoms. Specific examples of such divalent chain hydrocarbon groups with 1 to 20 carbon atoms include: alkyl dimethyl, alkyl ethyl, 1,3-propanediyl, 1,2-propanediyl, 2,2-propanediyl, 1,4-butanediyl, 1,3-butanediyl, 1,2-butanediyl, 2,2-butanediyl, pentanediyl, etc.; alkyl dimethyl, 1,3-propenediyl, 1,4-butenediyl, 1,5-pentenediyl, etc.; alkyl dimethyl, 1,3-propenediyl, 1,4-butenediyl, 1,5-pentenediyl, etc.

[0024] Examples of divalent alicyclic hydrocarbon groups with 3 to 20 carbon atoms include: monocyclic alicyclic saturated hydrocarbon groups such as cyclopropanediyl, cyclobutanediyl, cyclopentanediyl, and cyclohexanediyl; polycyclic alicyclic saturated hydrocarbon groups such as norbornanediyl, adamantanediyl, tricyclodecanediyl, and tetracyclododecanediyl; monocyclic alicyclic unsaturated hydrocarbon groups such as cyclopropenediyl, cyclobutenediyl, cyclopentenediyl, and cyclohexenediyl; and polycyclic alicyclic saturated hydrocarbon groups such as norbornenediyl and tricyclodecenediyl. Furthermore, the divalent alicyclic hydrocarbon group represented by Y1 can also be a group formed by bonding a divalent aliphatic cyclic group such as cyclopropanediyl or cyclopentanediyl with the aforementioned divalent chain hydrocarbon group.

[0025] As divalent aromatic hydrocarbon groups with 6 to 20 carbon atoms, examples include: phenylene, methyl phenylene, xylene, naphthyl, anthracene, etc.; and groups represented by *1-Ar4-R22- or *1-R22-Ar4- (where Ar4 is a substituted or unsubstituted phenylene, R22 is a divalent chain hydrocarbon group, and "*1" indicates a bond with X1 in formula (1)).

[0026] Furthermore, when X1 is a single bond, Y1 is bonded to Ar1 via a carbon atom. Specific examples of Y1 that are bonded to Ar1 via a carbon atom include groups that are saturated or unsaturated chain hydrocarbon groups, saturated or unsaturated alicyclic hydrocarbon groups, aromatic hydrocarbon groups, or carbonyl groups. Further specific examples of Y1 when Y1 bonds with Ar1 through a carbon atom include: * 2-CH 2-R 23-, * 2-CH=CH-R 23-, * 2-C≡CR 23-, * 2-CO-R 23-, * 2-Ph 1-R 23-, * 2-Cy 1-R 23- (Ph 1 is a substituted or unsubstituted phenyl group, Cy 1 is a substituted or unsubstituted cycloalkyl group, R 23 is a single bond or a divalent organic group, and "* 2" indicates the bond with Ar1), etc. Specific examples of divalent organic groups represented by R 23 include: divalent hydrocarbon groups with 1 to 18 carbon atoms; divalent hydrocarbon groups with 1 to 18 carbon atoms formed by substitution of any methyl group with -O-, -S-, -CO-, -COO-, -OCO-, -NR-, -NR 10CO-, -CONR 10-, -NR 10COO-, -OCONR 10-, -NR 10-CO-NR 11-, etc.; and groups with heterocyclic structures.

[0027] From the viewpoint of sufficiently reducing the residual charge accumulated in the liquid crystal element and improving the transmittance of the liquid crystal element, Y1 in formula (1) is preferably partially or entirely a chain structure, and is bonded to the nitrogen atom of Ar3 through the chain structure. In this case, the chain structure of Y1 at the nitrogen atom bonding site (i.e., the end of Y1 on the Ar2 side) can be saturated or unsaturated, and can be straight-chain or branched. From the viewpoint of further improving the effect of reducing the accumulated residual charge and improving the transmittance, Y1 is preferably bonded to the nitrogen atom of Ar3 through a divalent straight-chain hydrocarbon group, and more preferably bonded to the nitrogen atom of Ar3 through a straight-chain alkane group.

[0028] From the viewpoint of minimizing image retention and bright spots in liquid crystal elements, the group represented by "-X1-Y1-" preferably has X1 as -O-, -S-, or -NR1- and Y1 as a divalent organic group, or X1 as a single bond and part or all of Y1 as a chain structure and Y1 as bonded to Ar1 through the chain structure. In the case of X1 as a single bond, from the viewpoint of further improving the reduction effect of accumulated residual charge and the improvement effect of transmittance, Y1 is preferably bonded to Ar1 through a divalent straight-chain hydrocarbon group, and more preferably through a straight-chain alkane diene group.

[0029] In the above, the base represented by "-X 1-Y 1-" is preferably Y 1, which is a divalent chain base. Specifically, Y1 is preferably a divalent chain hydrocarbon group having 1 to 20 carbons, or a divalent group having 1 to 20 carbons in which any of the elongated methyl groups of the chain hydrocarbon group is replaced by -O-, -S-, -CO-, -COO-, -OCO-, -NR-, -NR 10CO-, -CONR 10-, -NR 10COO-, -OCONR 10- or -NR 10-CO-NR 11-. More preferably, it is an alkadiyl group having 1 to 20 carbons, or a divalent group having 1 to 20 carbons in which any of the elongated methyl groups of the alkadiyl group is replaced by -O-, -S-, -CO-, -COO-, -OCO-, -NR-, -NR 10CO-, -CONR 10-, -NR 10COO-, -OCONR 10- or -NR 10-CO-NR 11-. Furthermore, R 10 and R 11 have the same meaning as described above.

[0030] When Y1 is a divalent chain group, from the viewpoint of obtaining a liquid crystal alignment film with sufficiently high mechanical strength, the number of carbons in Y1 is preferably 10 or less, more preferably 4 or less. Furthermore, from the viewpoint of reducing the accumulated charge in the liquid crystal alignment film or liquid crystal element, the number of carbons in Y1 is preferably 1 or more, more preferably 2 or more. When X1 is a single bond and Y1 is a divalent chain group, from the viewpoint of compound stability, the number of carbons in Y1 is preferably 2 or more.

[0031] In terms of significantly improving the transmittance of the obtained liquid crystal alignment film, X1 is preferably -O- or -S-, and more preferably -O-.

[0032] When Ar 2, Ar 3, and Y 1 satisfy the aforementioned requirement (ii), the nitrogen-containing aromatic fused ring structure formed by the interweaving of Ar 2 and Ar 3 and together with the nitrogen atoms bonded to Ar 2 and Ar 3 can be exemplified by carbazole ring structures, acridine ring structures, etc. Among these, the nitrogen-containing aromatic fused ring structure is preferably a carbazole ring structure. In the nitrogen-containing aromatic fused ring structure, the nitrogen-containing aromatic fused ring may have substituents. Examples of such substituents include: methyl, ethyl, hydroxyl, halogen atoms, etc. Specific and preferred examples of the divalent aromatic ring group represented by Ar 1, the group represented by X 1, and the divalent organic group represented by Y 1 can be exemplified by groups that are the same as those described when Ar 2, Ar 3, and Y 1 satisfy the aforementioned requirement (i).

[0033] When Ar2, Ar3, and Y1 satisfy the aforementioned requirement (iii), in the divalent group (hereinafter also referred to as "divalent group ArY") comprising a nitrogen-containing aromatic fused ring structure in which Ar3 and Y1 are bonded together and together with the nitrogen atoms bonded to Ar3 and Y1, specific examples and preferred examples of the nitrogen-containing aromatic fused ring structure can be cited as the same groups described when Ar2, Ar3, and Y1 satisfy the aforementioned requirement (ii). In the divalent group ArY, the nitrogen-containing aromatic fused ring can be directly bonded to X1 or Ar1, or the nitrogen-containing aromatic fused ring can be bonded to X1 or Ar1 via a divalent linker. The divalent linker is preferably partially or entirely a chain structure, more preferably a straight-chain alkanediol, and even more preferably a straight-chain alkanediol with 1 to 4 carbon atoms. Specific and preferred examples of the divalent aromatic cyclic group represented by Ar 1 or Ar 2, and the group represented by X 1, can be listed as the same groups as those described when Ar 2, Ar 3 and Y 1 satisfy the stated requirement (i).

[0034] Specific examples of a particular diamine include compounds represented by formulas (1-1) to (1-26) below. [Chemical 3][Chemical 4][Chemical 5]

[0035] In the polymer (P), the proportion of structural units derived from a specific diamine is preferably 0.5 mol% or more, more preferably 5 mol% or more, and more preferably 10 mol% or more, relative to all structural units derived from the monomer constituting the polymer (P). Furthermore, the proportion of structural units derived from a specific diamine is preferably 50 mol% or less, relative to all structural units derived from the monomer constituting the polymer (P).

[0036] The polymer (P) can be any polymer containing structural units derived from a specific diamine, and the type of its main backbone is not particularly limited. Examples of polymers (P) include: polyamide, polyamide ester, polyimide, polyamide, polyamide-polyimide, polyurea, polyenamine, etc. In terms of forming liquid crystal alignment films with high mechanical strength and obtaining liquid crystal elements with high reliability, the polymer (P) is preferably at least one selected from the group consisting of polyamide, polyamide ester, and polyimide. That is, the polymer (P) is preferably a polymer containing structural units derived from tetracarboxylic acid derivatives and structural units derived from diamine compounds.

[0037] [Polyamide] In the case where the polymer (P) is polyamide, the polyamide (hereinafter also referred to as "polyamide (P)") can be obtained by reacting a tetracarboxylic acid dianhydride with a diamine compound containing a specific diamine.

[0038] • Tetracarboxylic dianhydrides used in the synthesis of polyacrylic acid (P) include, for example, aliphatic tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides. As aliphatic tetracarboxylic dianhydrides, examples include chain tetracarboxylic dianhydrides and alicyclic tetracarboxylic dianhydrides.

[0039] Specific examples of these include, as chain-like tetracarboxylic dianhydrides, 1,2,3,4-butanetetracarboxylic dianhydride and ethylenediaminetetraacetic acid dianhydride, etc. Examples of alicyclic tetracarboxylic dianhydrides include: 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxylated cyclopentylacetic 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)-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, etc. Oxotetrahydrofuran-3-yl)-8-methyl-3a,4,5,9b-tetrahydronaphtho[1,2-c]furan-1,3-dione, 2,4,6,8-tetracarboxylic bicyclo[3.3.0]octane-2:4,6:8-dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, 3,5,6-tricarboxy-2-carboxymethylnorbornene-2:3,5:6-dianhydride, etc.

[0040] Examples of aromatic tetracarboxylic acid dianhydrides include: pyromellitic dianhydride, 4,4'-(hexafluoroethylene isopropyl) phthalic anhydride, ethylene glycol dimethacrylate anhydride, 4,4'-carbonyl phthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, and 3,3',4,4'-biphenyl ether tetracarboxylic acid dianhydride. Furthermore, in the synthesis of polyamide (P), the tetracarboxylic acid dianhydride described in Japanese Patent Application Publication No. 2010-97188 can be used.

[0041] (Diamine Compounds) The diamine compound used in the synthesis of polyamide (P) may be only a specific diamine, or it may combine a specific diamine with a diamine different from the specific diamine (hereinafter also referred to as "other diamines"). Examples of other diamines include: aliphatic diamines, aromatic diamines, diamino organosilicones, etc. Examples of aliphatic diamines include chain diamines and alicyclic diamines.

[0042] Specific examples of other diamines include, as chain diamines, meta-xylylenediamine, hexamethylenediamine, etc. As alicyclic diamines, 1,4-diaminocyclohexane, 4,4'-amethylenebis(cyclohexylamine), etc.

[0043] Examples of aromatic diamines include: p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4-aminophenyl-4-aminobenzoic acid ester, 4,4'-diaminoazobenzene, 3,5-diaminobenzoic acid, 1,5-bis(4-aminophenoxy)pentane, 1,2-bis(4-aminophenoxy)ethane, 1,3-bis(4-aminophenoxy)propane, 1,6-bis(4-aminophenoxy)hexane, 6,6'-(pentanedimethyldioxy)bis(3-aminopyridine), N,N'-di(5-amino-2-pyridyl)-N,N'-di(tert-butoxycarbonyl)ethylenediamine, and bis[2-(4-aminophenyl)ethyl] Adipic acid, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenylethyl urea, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 2,2'-dimethyl-4,4'-diaminobiphenyl, 4,4'-(dipropylphenyldiisopropyl)bisaniline, 2,6-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 3,6-diaminoacridine, and other main-chain diamines represented by the following formula (D-1); [Chemical 6] (In formula (D-1), R11 and R12 are each independently an alkyl group; R13 is a hydrogen atom, an alkyl group with 1 to 3 carbon atoms, or a thermally detachable group; n1 is an integer from 1 to 3; when n1 is 2 or 3, multiple R12s may be the same or different from each other, and multiple R13s may be the same or different from each other) Hexadecyloxy-2,4-diaminobenzene, Octadecyloxy-2,4-diaminobenzene, Octadecyloxy-2,5-diaminobenzene, Cholesteryloxy-3,5-diaminobenzene, Cholesteryloxy-3,5-diaminobenzene, Cholesteryloxy-2,4-diaminobenzene, Cholesteryloxy-2,4-diaminobenzene, Cholesteryl ester of 3,5-diaminobenzoate, Cholesteryl ester of 3,5-diaminobenzoate, 3,5-diaminobenzoate Side-chain diamines such as cyclohexyl esters, 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, 3,5-diaminobenzoic acid =5ξ-cholestane-3-yl, and compounds represented by the following formula (E-1); [Chemical 7] (in formula (E-1), XI and XII are independently single bonds, -O-, *-COO- or *-OCO- (where "*" indicates a bond with XI); RI is an alkyl dieny with 1 to 3 carbon atoms; RII is a single bond or an alkyl dieny with 1 to 3 carbon atoms;R III is an alkyl, alkoxy, fluoroalkyl, or 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; where 1 ≦ a + b + c ≦ 3). Examples of diamino organosiloxanes include 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, etc.

[0044] Examples of compounds represented by formula (D-1) include those represented by formulas (D-1-1) to (D-1-3). Examples of compounds represented by formula (E-1) include those represented by formulas (E-1-1) to (E-1-4). Examples of other diamines include those represented by formulas (F-1) to (F-7). Other diamines may be used individually or in combination of two or more. Furthermore, in the formula, "Boc" represents a third butoxycarbonyl group (the same applies below). [Chemical 8][Chemical 9]

[0045] When synthesizing polyacrylic acid (P), the amount of a specific diamine used is preferably 1 mol% or more, more preferably 5 mol% or more, and even more preferably 10 mol% or more, and even more preferably 20 mol% or more, relative to the total amount of diamine compound used in the synthesis of polyacrylic acid (P). By setting the amount of the specific diamine used within the aforementioned range, the improvement effect of suppressing bright spots and reducing image retention in the liquid crystal element can be sufficiently obtained.

[0046] • Synthesis of polyamide Polyamide (P) can be obtained by reacting a tetracarboxylic acid dianhydride and a diamine compound with a molecular weight modifier as needed.

[0047] In the synthesis reaction of polyacrylic acid (P), the ratio of tetracarboxylic dianhydride to diamine compound is preferably such that the ratio of the anhydride group of the tetracarboxylic dianhydride to the amino group of the diamine compound is 0.2 to 2 equivalents. Examples of molecular weight modifiers include: maleic anhydride, phthalic anhydride, itaconic anhydride, and other monohydric anhydrides; monoamine compounds such as aniline, cyclohexylamine, and n-butylamine; and monoisocyanate compounds such as phenyl isocyanate and naphthyl isocyanate. The ratio of the molecular weight modifier to the total 100 parts by mass of the tetracarboxylic dianhydride and diamine compound used is preferably 20 parts by mass or less.

[0048] In the synthesis reaction of polyacrylic acid (P), the reaction temperature is preferably -20°C to 150°C, and the reaction time is preferably 0.1 hours to 24 hours. Examples of organic solvents used for the reaction include: aprotic polar solvents, phenolic solvents, alcoholic solvents, ketone solvents, ester solvents, ether solvents, halogenated hydrocarbons, and hydrocarbons. Among these, it is preferred to use one or more solvents selected from the group consisting of N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphoric acid triamine, m-cresol, xylenol, and halogenated phenols, or a mixture of one or more of these solvents with other organic solvents (e.g., butyl cellosolve, diethylene glycol diethyl ether, etc.). The amount of organic solvent used is preferably set relative to the total amount of the reaction solution, while the total amount of tetracarboxylic acid dianhydride and diamine compound is 0.1% to 50% by mass.

[0049] When a polymer solution containing polyacrylic acid (P) is obtained by the polymerization, the polymer solution can be directly used in the preparation of a liquid crystal alignment agent, or it can be used in the preparation of a liquid crystal alignment agent after separating the polyacrylic acid (P) contained in the polymer solution.

[0050] [Polyamide] When the polymer (P) is a polyamide, the polyamide can be obtained, for example, by the following methods: [I] reacting polyamide (P) with an esterifying agent; [II] reacting a tetracarboxylic acid diester with a diamine compound; [III] reacting a tetracarboxylic acid diester dihalide with a diamine compound. The polyamide may have only a polyamide structure, or it may be a partial esterification in which both a polyamide structure and a polyamide structure coexist. The reaction solution obtained by dissolving the polyamide can be directly used in the preparation of a liquid crystal alignment agent. Alternatively, the polyamide contained in the reaction solution can be separated, and the separated polyamide can be used in the preparation of a liquid crystal alignment agent.

[0051] [Polyimide] When the polymer (P) is a polyimide, the polyimide (hereinafter also referred to as "polyimide (P)") can be obtained, for example, by dehydrating and ring-closing polyamide (P) and then amide-imidizing it. The polyimide (P) can be a fully amide-imidized product obtained by completely dehydrating and ring-closing the amide structure of the polyamide (P) as its precursor, or it can be a partially amide-imidized product obtained by dehydrating and ring-closing only a portion of the amide structure, resulting in the coexistence of the amide structure and the amide ring structure. Preferably, the polyimide (P) has an amide-imidization rate of 20% to 99%, more preferably 30% to 90%. Furthermore, the amide ratio is expressed as a percentage, representing the proportion of the number of amide ring structures relative to the total number of amide acid structures and amide ring structures in the polyamide. Here, a portion of the amide ring may be an isoamide ring.

[0052] The dehydration and ring-closing of polyacrylic acid (P) is preferably carried out by the following method: dissolving polyacrylic acid (P) in an organic solvent, adding a dehydrating agent and a dehydration and ring-closing catalyst to the solution, and heating as needed. In this method, anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used as dehydrating agents. The amount of dehydrating agent used is preferably 0.01 mol to 20 mol relative to 1 mol of the polyacrylic acid structure of polyacrylic acid (P). Tertiary amines such as pyridine, trimethylpyridine, dimethylpyridine, and triethylamine can be used as dehydration and ring-closing catalysts. The amount of dehydration and ring-closing catalyst used is preferably 0.01 mol to 10 mol relative to 1 mol of the dehydrating agent used.

[0053] Examples of organic solvents used in the dehydration ring-closure reaction include those used in the synthesis of polyamide (P). The reaction temperature for the dehydration ring-closure reaction is preferably 0°C to 180°C. The reaction time is preferably 1.0 h to 120 h. The reaction solution containing polyimide (P) obtained by the dehydration ring-closure reaction of polyamide (P) can be directly used in the preparation of liquid crystal alignment agents. Alternatively, polyimide (P) can be separated from the reaction solution and used in the preparation of liquid crystal alignment agents. Polyimide (P) can also be obtained by the dehydration ring-closure of polyamide esters.

[0054] When preparing a solution with a concentration of 10% by mass, the solution viscosity of the polymer (P) is preferably between 10 mPa·s and 800 mPa·s, and more preferably between 15 mPa·s and 500 mPa·s. Furthermore, the solution viscosity (mPa·s) is a value obtained by measuring a 10% by mass polymer solution prepared using a good solvent for the polymer (P) (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.) at 25°C using an E-type rotational viscometer.

[0055] The weight-average molecular weight (Mw) of the polymer (P) converted from polystyrene, as determined by gel permeation chromatography (GPC), is preferably 1,000 to 500,000, more preferably 2,000 to 300,000. The molecular weight distribution (Mw / Mn) expressed as the ratio of Mw to the number-average molecular weight (Mn) of polystyrene determined by GPC is preferably 7 or less, more preferably 5 or less.

[0056] Relative to the total amount of solid components contained in the liquid crystal alignment agent (i.e., the total mass of components other than the solvent in the liquid crystal alignment agent), the content of polymer (P) in the liquid crystal alignment agent is preferably 20% by mass or more, more preferably 40% by mass or more, and even more preferably 60% by mass or more.

[0057] Here, in order to suppress image retention caused by charge accumulation, it is ideal to reduce both the image retention observed immediately after the voltage is released (i.e., short-term) and the image retention observed after a sufficient time has elapsed since the voltage was released (i.e., long-term) (hereinafter also referred to as "long-term image retention"). On the other hand, based on the research of the inventors, there is a trade-off between short-term and long-term image retention, and there is a tendency that if one is improved, the other will deteriorate. In addition, the same applies to the transmittance of the liquid crystal element, for example, if the long-term image retention is reduced, there is a tendency that the transmittance of the liquid crystal element will decrease. In contrast, according to this disclosure, by using a polymer (P) to form a liquid crystal alignment film, both short-term and long-term image retention can be reduced, while high transmittance can be achieved. In addition, regarding the diamine represented by the formula (1) constituting the polymer (P), when a reference axis is placed in the direction intersecting the direction in which the main chain extends, it has an asymmetrical structure on both sides of the reference axis. Therefore, it can be considered that the polymer (P) containing structural units derived from the diamine represented by formula (1) has low crystallinity, and even if decomposition products are generated due to heat or light, the decomposition products are difficult to crystallize. As a result, it can be considered that the generation of bright spots can be suppressed according to the liquid crystal alignment agent containing the polymer (P).

[0058] <Other Components> In addition to the polymer (P), the liquid crystal alignment agent may also contain components different from the polymer (P) as needed (hereinafter also referred to as "other components").

[0059] [Polymer (Q)] The liquid crystal alignment agent disclosed herein may further contain a polymer (hereinafter also referred to as "polymer (Q)") that does not contain structural units derived from a specific diamine. The main skeleton of the polymer (Q) is not particularly limited. Examples of polymer (Q) include: polyamide, polyamide ester, polyimide, polyorganosiloxane, polyester, polyenamine, polyurea, polyamide, polyamide-imide, polybenzoxazole precursor, polybenzoxazole, cellulose derivative, polyacetal, addition polymer (e.g., (meth)acrylic acid polymer, styrene polymer, maleimide polymer, styrene-maleimide copolymer), etc. Among these, polymer (Q) is preferably selected from at least one of the group consisting of polyamide, polyamide ester, polyimide, polyorganosiloxane and addition polymer.

[0060] When the liquid crystal alignment agent contains polymer (Q), the proportion of polymer (Q) is preferably 1 part by mass or more, and more preferably 2 parts by mass or more, relative to 100 parts by mass of the total amount of polymer (P) and polymer (Q) contained in the liquid crystal alignment agent. Furthermore, the proportion of polymer (Q) is preferably 95 parts by mass or less, and more preferably 90 parts by mass or less, relative to 100 parts by mass of the total amount of polymer (P) and polymer (Q) contained in the liquid crystal alignment agent.

[0061] [Solvent] The liquid crystal alignment agent of this disclosure is prepared as a liquid composition in which the polymer (P) and other components used as needed are preferably dispersed or dissolved in a suitable solvent.

[0062] Organic solvents are preferably used as solvents. Specific examples include: N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,2-dimethyl-2-imidazolium ketone, 1,3-dimethyl-2-imidazolium ketone, phenol, γ-butyrolactone, γ-butyrolactamine, N,N-dimethylformamide, N,N-dimethylacetamide, 4-hydroxy-4-methyl-2-pentanone, diacetone alcohol, 1-hexanol, 2-hexanol, propane-1,2-diol, 3-methoxy-1-butanol, ethylene glycol monomethyl ether, methyl lactate, ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, acetoacetic acid. Methyl acetate, ethyl acetate, ethyl propionate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-isopropyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diisobutyl ketone, isoamyl propionate, isoamyl isobutyrate, diisoamyl ether, ethyl carbonate, propyl carbonate, propylene glycol monomethyl ether (PGME), diethylene glycol diethyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol diacetate, cyclopentanone, cyclohexanone, etc. As a solvent, it can be used alone or in combination with two or more.

[0063] Other components formulated into the liquid crystal alignment agent, besides those described above, may include, for example, crosslinking agents, antioxidants, metal chelate compounds, curing accelerators, surfactants, fillers, dispersants, photosensitizers, etc. The formulation ratio of other components may be appropriately selected according to each compound, within the range that does not impair the effects of this disclosure.

[0064] The solid content concentration of the liquid crystal alignment agent (the ratio of the total mass of the liquid crystal alignment agent's components other than the solvent to the total mass of the liquid crystal alignment agent) is appropriately selected considering factors such as viscosity and volatility. The solid content concentration of the liquid crystal alignment agent is preferably in the range of 1% to 10% by mass. If the solid content concentration is 1% by mass or more, the film thickness of the coating can be sufficiently ensured, and a liquid crystal alignment film exhibiting better liquid crystal alignment properties can be obtained, which is suitable in this respect. On the other hand, if the solid content concentration is 10% by mass or less, there is a tendency that the coating can be set to an appropriate thickness, a liquid crystal alignment film exhibiting good liquid crystal alignment properties can be easily obtained, and the viscosity of the liquid crystal alignment agent becomes moderate, resulting in good coatability.

[0065] Liquid Crystal Alignment Film and Liquid Crystal Element The liquid crystal alignment film disclosed herein can be manufactured using a liquid crystal alignment agent prepared as described above. Furthermore, the liquid crystal element disclosed herein includes a liquid crystal alignment film formed using the liquid crystal alignment agent described above. The driving method of the liquid crystal in a liquid crystal element is not particularly limited. For example, it can be applied to various modes such as twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA) (including vertical alignment-multi-domain vertical alignment (VA-MVA) and vertical alignment-patterned vertical alignment (VA-PVA), in-plane switching (IPS), fringe field switching (FFS), optically compensated bending (OCB), and polymer-stable alignment (PSA). The liquid crystal element can be manufactured, for example, using a method including steps 1 to 3. In step 1, the substrate used varies depending on the desired operating mode. Steps 2 and 3 are common in all operating modes.

[0066] <Step 1: Formation of the coating> First, a coating is formed on the substrate by coating a liquid crystal alignment agent onto the substrate, preferably by heating the coated surface. Examples of substrates that can be used include: float glass, soda glass, etc.; and transparent substrates containing plastics such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, and poly(alicyclic olefins). As a transparent conductive film disposed on one side of the substrate, a NESA film (a registered trademark of PPG Industries, Inc.) containing tin oxide (SnO 2) or an indium tin oxide (ITO) film containing indium oxide-tin oxide (In 2O 3-SnO 2) can be used. In the case of manufacturing TN, STN, or VA type liquid crystal elements, two substrates with patterned transparent conductive films are used. On the other hand, when manufacturing IPS or FFS type liquid crystal elements, a substrate with electrodes patterned into a comb shape and an opposing substrate without electrodes are used.

[0067] There is no particular limitation on the method of coating the substrate with the liquid crystal alignment agent. The coating of the liquid crystal alignment agent onto the substrate can be performed by, for example, spin coating, printing (e.g., offset printing, flexographic printing, etc.), inkjet printing, slot coating, bar coating, extrusion die coating, direct gravure coating, chamber doctor coating, offset gravure coating, impregnation coating, MB coating, etc.

[0068] After coating the liquid crystal alignment agent, it is preferable to perform preheating (pre-baking) to prevent sagging of the coated liquid crystal alignment agent. The pre-baking temperature is preferably 30°C to 200°C, and the pre-baking time is preferably 0.25 minutes to 10 minutes. Afterward, the solvent is completely removed, and a calcination (post-baking) step is performed as needed for the purpose of thermally imidizing the amide structure present in the polymer. The calcination temperature (post-baking temperature) is preferably 80°C to 280°C, more preferably 80°C to 250°C. The post-baking time is preferably 5 minutes to 200 minutes. The thickness of the formed film is preferably 0.001 μm to 1 μm.

[0069] <Step 2: Alignment Processing> In the case of manufacturing TN, STN, IPS, or FFS type liquid crystal elements, a process (alignment processing) is performed to impart liquid crystal alignment capability to the coating film formed in step 1. As a result, the alignment capability of the liquid crystal molecules is imparted to the coating film, forming a liquid crystal alignment film. Preferably, the alignment processing involves rubbing the surface of the coating film formed on the substrate with cotton or nylon, or photoalignment processing by irradiating the coating film with light to impart liquid crystal alignment capability. In the case of manufacturing vertically aligned liquid crystal elements, the coating film formed in step 1 can be used directly as a liquid crystal alignment film. Alternatively, alignment processing can be performed on the coating film to further improve the liquid crystal alignment capability. A liquid crystal alignment film suitable for vertically aligned liquid crystal elements can also preferably be used for PSA type liquid crystal elements.

[0070] Light irradiation for photoalignment can be performed by methods such as: irradiating a coating after a post-baking step; irradiating a coating after a pre-baking step and before a post-baking step; or irradiating the coating during heating in at least one of the pre-baking and post-baking steps. As the radiation irradiating the coating, for example, ultraviolet light and visible light containing wavelengths of 150 nm to 800 nm can be used. Ultraviolet light containing wavelengths of 200 nm to 400 nm is preferred. When the radiation is polarized, it can be linearly polarized or partially polarized. When the radiation used is linearly polarized or partially polarized, irradiation can be performed from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these directions. For unpolarized radiation, the irradiation direction is set to an oblique direction.

[0071] Examples of light sources used include: low-pressure mercury lamps, high-pressure mercury lamps, deuterium lamps, metal halide lamps, argon resonant lamps, xenon lamps, and excimer lasers. The radiation dose is preferably 200 J / m² to 30,000 J / m², more preferably 500 J / m² to 10,000 J / m². After irradiation with light to impart alignment capability, the substrate surface may be cleaned using, for example, water, an organic solvent (e.g., methanol, isopropanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, etc.), or a mixture thereof, or the substrate may be heated.

[0072] <Step 3: Construction of the liquid crystal cell> Two substrates with liquid crystal alignment films formed as described above are prepared, and a liquid crystal cell is manufactured by distributing liquid crystal between the two substrates arranged facing each other. When manufacturing the liquid crystal cell, methods such as: arranging the two substrates facing each other with the liquid crystal alignment films facing each other and a gap between them; bonding the peripheries of the two substrates together using a sealant; injecting and filling liquid crystal into the cell gap surrounded by the substrate surface and the sealant and sealing the injection hole; or using a liquid crystal drop filling (ODF) method. As a sealant, for example, epoxy resin containing a hardener and alumina spheres as spacers can be used. As a liquid crystal, nematic liquid crystal and smectic liquid crystal can be used, with nematic liquid crystal being preferred.

[0073] In the PSA mode, the following process is performed: a polymeric compound (e.g., a polyfunctional (meth)acrylate compound, etc.) is filled into the cell gap along with the liquid crystal, and after the liquid crystal cell is constructed, the liquid crystal cell is irradiated with light while a voltage is applied between the conductive films of a pair of substrates. When manufacturing a PSA type liquid crystal element, the proportion of the polymeric compound used relative to 100 parts by mass of the total liquid crystal is, for example, 0.01 parts by mass to 3 parts by mass, preferably 0.05 parts by mass to 1 part by mass.

[0074] In the case of manufacturing a liquid crystal display device, a polarizing plate is then attached to the outer surface of the liquid crystal cell. Examples of polarizing plates include: a polarizing plate made by clamping a polarizing film called an "H film" which is formed by extending and aligning polyvinyl alcohol on one side and absorbing iodine on the other side using a cellulose acetate protective film, or a polarizing plate that includes the H film itself.

[0075] The liquid crystal element disclosed herein can be effectively applied to a variety of uses. Specifically, it can be used, for example, as a clock, handheld game console, word processor, laptop computer, car navigation system, camcorder, personal digital assistant (PDA), digital camera, mobile phone, smartphone, various monitors, LCD TVs, information displays and other display devices or dimming devices, phase retardation film, etc.

[0076] The present disclosure described above provides the following means. [Means 1] A liquid crystal alignment agent comprising a polymer (P) having a structural unit derived from a compound represented by formula (1). [Means 2] The liquid crystal alignment agent according to [Means 1], wherein X1 in formula (1) is -O-, -S-, or -NR1-, or X1 is a single bond and Y1 is partially or entirely chain-like, and Y1 is bonded to Ar1 through the chain-like structure. [Means 3] The liquid crystal alignment agent according to [Means 1] or [Means 2], wherein Y1 in formula (1) is a divalent organic group having one or more carbon atoms, is partially or entirely chain-like, and is bonded to a nitrogen atom bonded to Ar3 through the chain-like structure. [Means 4] The liquid crystal alignment agent according to any one of [Means 1] to [Means 3], wherein the polymer (P) is at least one selected from the group consisting of polyamide, polyamide ester, and polyimide. [Method 5] The liquid crystal alignment agent according to any one of [Method 1] to [Method 4] further comprises a polymer (Q) that does not have a structural unit derived from the compound represented by formula (1). [Method 6] The liquid crystal alignment agent according to [Method 5], wherein the polymer (Q) is at least one selected from the group consisting of polyamide, polyamide ester, polyimide, polyorganosiloxane and addition polymers. [Method 7] A liquid crystal alignment film formed using the liquid crystal alignment agent according to any one of [Method 1] to [Method 6]. [Method 8] A liquid crystal element comprising the liquid crystal alignment film according to [Method 7]. [Examples]

[0077] Hereinafter, the implementation will be described in more detail based on the embodiments, but the present invention is not to be interpreted in a limited manner by the following embodiments.

[0078] In the following examples, the amide content of the polyimide in the polymer solution, as well as the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the polymer, are determined by the following methods. The required amounts of the starting material compounds and polymers used in the following examples are ensured by repeating the synthesis at the scale shown in the following synthesis examples as needed.

[0079] [Imidification rate of polyimide] A solution of polyimide was added to pure water, and the resulting precipitate was thoroughly dried under reduced pressure at room temperature. It was then dissolved in deuterated dimethyl silane and measured by 1H-NMR at room temperature using tetramethylsilane as a reference. Based on the obtained 1H-NMR spectrum, the amide ratio [%] was calculated using the following formula (I). Imidification rate [%] = (1 - (A1 / (A2×α))) × 100 … (I) (In formula (I), A1 is the peak area of ​​protons originating from NH groups appearing near a chemical shift of 10 ppm, A2 is the peak area of ​​other protons, and α is the ratio of other protons to the number of protons in the precursor of the polymer (polyimide) of one proton of an NH group).

[0080] [Weight-average molecular weight (Mw) and number-average molecular weight (Mn)] Mw and Mn are polystyrene conversion values ​​determined by GPC under the following conditions: Column: Tosoh Corporation, TSKgelGRCXLII; Solvent: Tetrahydrofuran; Temperature: 40°C; Pressure: 68 kgf / cm²

[0081] The abbreviation for the compound is as follows. Furthermore, in the following, the compound represented by formula (X) is sometimes simply referred to as "compound (X)". (Tetracarboxylic acid dianhydride) [Chemical 10]

[0082] (Diamine compound) [Chemical 11][Chemical 12][Chemical 13][Chemical 14]

[0083] [Chemistry 15][Chemistry 16]

[0084] (Other monomers) [Chemistry 17][Chemistry 18][Chemistry 19]

[0085] (Additive) [Chemical 20]

[0086] <Synthesis of Polymers> 1. Synthesis of Polyamide [Synthesis Example 1] 95 moles of compound (TA-3) as a tetracarboxylic dianhydride, 5 moles of compound (TA-8), 80 moles of compound (DA-1) as a diamine compound, and 20 moles of compound (DB-5) were dissolved in N-methyl-2-pyrrolidone (NMP) and reacted at room temperature for 6 hours to obtain a solution containing 15% by mass of polyamide (which is designated as polymer (PI-1)).

[0087] [Synthetic Examples 2-10, 12-14, 16-18, 20, 21, 24, 26, 28-30, 32, 33, 35-38] The types and amounts of tetracarboxylic dianhydrides and diamine compounds used were changed as described in Tables 1 and 2. Otherwise, the same operation as in Synthetic Example 1 was performed to obtain a solution containing polyamide (polymers (PI-2)-(PI-10), (PI-12)-(PI-14), (PI-16)-(PI-18), (PI-20), (PI-21), (PI-24), (PI-26), (PI-28)-(PI-30), (PI-32), (PI-33), (PI-35)-(PI-38)).

[0088] 2. Synthesis of Polyimide [Synthesis Example 11] 80 moles of compound (DA-11) and 20 moles of compound (DB-12), which are diamine compounds, were dissolved in N-methyl-2-pyrrolidone (NMP), and 90 moles of compound (TA-1) and 10 moles of compound (TA-3), which are tetracarboxylic dianhydrides, were added. The reaction was carried out at 40°C for 24 hours to obtain a solution containing 20% ​​by mass of polyamide. Subsequently, NMP was added to the obtained polymer solution to prepare a solution with a polyamide concentration of 10% by mass. Pyridine and acetic anhydride were added, and a dehydration and ring-closing reaction was carried out at 90°C for 4 hours. After the dehydration and ring-closing reaction, the solvent in the system was replaced with fresh NMP to obtain a solution containing 15% by mass of polyimide (designated as polymer (PI-11)) with a amide content of about 60%.

[0089] [Synthetic Examples 15, 19, 22, 23, 25, 27, 31, 34] The types and amounts of the tetracarboxylic dianhydride and diamine compounds used were changed as described in Tables 1 and 2. Otherwise, the same operation as in Synthetic Example 11 was performed to obtain a solution containing polyimides (polymers (PI-15), (PI-19), (PI-22), (PI-23), (PI-25), (PI-27), (PI-31), (PI-34)). The amide content of each polymer is shown in Table 1.

[0090] [Table 1] Polymer Name Acid dianhydride 1 acid dianhydride 2 Diamine 1 Diamine 2 Diamine 3 Diamine 4 aceimide rate (%) type Mörby type Mörby type Mörby type Mörby type Mörby type Mörby Synthesis example 1 PI-1 TA-3 95 TA-8 5 DA-1 80 DB-5 20 Synthesis example 2 PI-2 TA-8 100 DA-2 50 DB-5 50 Synthesis example 3 PI-3 TA-2 100 DA-3 60 DA-7 40 Synthesis example 4 PI-4 TA-1 95 TA-4 5 DA-4 80 DB-3 20 Synthesis example 5 PI-5 TA-3 90 TA-7 10 DA-5 30 DB-5 40 DB-8 30 Synthesis example 6 PI-6 TA-6 90 TA-9 10 DA-6 90 DB-14 10 Synthesis Example 7 PI-7 TA-3 70 TA-5 30 DA-7 50 DB-5 40 DB-8 10 Synthesis example 8 PI-8 TA-8 95 TA-3 5 DA-8 30 DB-4 50 DB-10 20 Synthesis example 9 PI-9 TA-9 100 DA-9 70 DB-11 30 Synthesis example 10 PI-10 TA-8 80 TA-9 20 DA-10 10 DB-2 40 DB-13 30 DB-15 20 Synthesis example 11 PI-11 TA-1 90 TA-3 10 DA-11 80 DB-12 20 60 Synthesis example 12 PI-12 TA-3 100 DA-12 90 DB-6 10 Synthesis example 13 PI-13 TA-1 95 TA-3 5 DA-13 70 DB-5 20 DB-6 10 Synthesis example 14 PI-14 TA-3 100 DA-14 50 DA-1 20 DB-16 30 Synthesis Example 15 PI-15 TA-1 100 DA-15 50 DB-5 40 DB-16 10 30 Synthesis Example 16 PI-16 TA-3 95 TA-8 5 DA-16 80 DB-5 20 Synthesis Example 17 PI-17 TA-1 100 DA-17 70 DB-1 30 Synthesis example 18 PI-18 TA-2 90 TA-9 10 DA-18 30 DB-5 40 DB-2 30 Synthesis example 19 PI-19 TA-8 100 DA-19 50 DB-5 50 30 Synthesis example 20 PI-20 TA-1 100 DA-20 80 DB-3 20

[0091] [Table 2] Polymer name Acid dianhydride 1 acid dianhydride 2 Diamine 1 Diamine 2 Diamine 3 Diamine 4 aceimide ratio (%) type Mörby type Mörby type Mörby type Mörby type Mörby type Mörby Synthesis Example 21 PI-21 TA-3 100 DB-1 60 DB-11 40 Synthesis example 22 PI-22 TA-1 100 DB-1 60 DB-11 40 30 Synthesis example 23 PI-23 TA-6 100 DA-1 30 DB-8 50 DB-1 20 80 Synthesis example 24 PI-24 TA-6 100 DA-14 40 DB-8 40 DB-1 20 Synthesis example 25 PI-25 TA-6 100 DB-1 50 DB-8 50 80 Synthesis Example 26 PI-26 TA-6 100 DA-17 30 DB-8 50 DB-1 20 Synthesis Example 27 PI-27 TA-6 100 DB-7 100 30 Synthesis example 28 PI-28 TA-8 90 TA-7 10 DA-15 50 DB-10 30 DB-11 20 Synthesis Example 29 PI-29 TA-8 90 TA-7 10 DB-10 80 DB-11 20 Synthesis example 30 PI-30 TA-3 100 DA-2 50 DB-5 30 DB-16 10 DB-17 10 Synthesis Example 31 PI-31 TA-1 100 DA-1 60 DB-5 30 DB-16 5 DB-18 5 60 Synthesis example 32 PI-32 TA-1 50 TA-2 50 DA-1 40 DB-5 30 DB-17 30 Synthesis example 33 PI-33 TA-3 100 DA-18 50 DB-5 30 DB-16 10 DB-17 10 Synthesis example 34 PI-34 TA-1 100 DB-5 90 DB-16 5 DB-18 5 60 Synthesis Example 35 PI-35 TA-1 50 TA-2 50 DA-18 40 DB-5 30 DB-17 30 Synthesis example 36 PI-36 TA-3 70 TA-1 30 DA-21 100 Synthesis Example 37 PI-37 TA-3 70 TA-2 30 DA-22 60 DB-5 40 Synthesis example 38 PI-38 TA-3 100 DA-23 70 DB-2 20 DB-5 10

[0092] 3. Synthesis of Polyorganosiloxanes [Synthesis Example 39] 100.0 g of 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (the compound represented by formula (S-1)) 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 mixture was refluxed while the reaction was carried out at 80°C for 6 hours. After the reaction was completed, the organic layer was removed and washed with 0.2% ammonium nitrate aqueous solution until the water was neutral. The solvent and water were then removed by distillation under reduced pressure. An appropriate amount of methyl isobutyl ketone was added to obtain a 50% solution of a polymer (ESSQ-1) as an epoxy-containing polyorganosiloxane. In a 500 mL three-necked flask, 3.10 g of compound (C-1) (20 mol% relative to the amount of epoxy groups in polymer (ESSQ-1), 3.24 g of compound (C-2) (10 mol% relative to the amount of epoxy groups in polymer (ESSQ-1), 1.00 g of tetrabutylammonium bromide, 20.0 g of a solution containing polymer (ESSQ-1), and 290.0 g of methyl isobutyl ketone were added and stirred at 90 °C for 18 hours. After cooling to room temperature, the mixture was subjected to 10 separate washing operations using distilled water. Subsequently, the organic layer was recovered, and the solution was concentrated twice using a rotary evaporator and diluted with NMP. The solution was then adjusted with NMP to a solids concentration of 10% by mass to obtain an NMP solution of the polyorganosiloxane (designated as polymer (PSQ-1)).

[0093] 4. Synthesis of styrene-maleimide copolymer [Synthesis Example 40] Under nitrogen atmosphere, 5.00 g of compound (M-1), 1.05 g of compound (M-2), 4.80 g of compound (M-3), and 2.26 g of compound (M-4) as monomers, 0.39 g of 2,2'-azobis(2,4-dimethylpentanilide) as a free radical polymerization initiator, 0.39 g of 2,4-diphenyl-4-methyl-1-pentene as a chain transfer agent, and 52.5 mL of N-methyl-2-pyrrolidone (NMP) as a solvent were added to a 100 mL two-necked flask, and polymerization was carried out at 70 °C for 6 hours. After reprecipitation in methanol, the precipitate was filtered and dried under vacuum at room temperature for 8 hours to obtain a styrene-maleimide copolymer (designated as polymer (MI-1)). The weight-average molecular weight (Mw) measured by GPC and converted to polystyrene is 30,000, and the molecular weight distribution (Mw / Mn) is 2.

[0094] [Synthesis Example 41] Under nitrogen atmosphere, 10 moles of compound (M-5), 10 moles of compound (M-6), 30 moles of compound (M-7), 10 moles of compound (M-8), 20 moles of compound (M-9), and 20 moles of compound (M-10) as monomers, 2 moles of 2,2'-azobis(2,4-dimethylpentanonitrile) as a free 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 6 hours. After reprecipitation in methanol, the precipitate was filtered and dried under vacuum at room temperature for 8 hours to obtain a styrene-maleimide copolymer (designated as polymer (MI-2)). The weight-average molecular weight (Mw) measured by GPC and converted to polystyrene was 92,700, and the molecular weight distribution (Mw / Mn) was 4.78.

[0095] <Preparation and Evaluation of Liquid Crystal Alignment Agent> • FFS Type Liquid Crystal Display Element [Example 1] 1. Preparation of Liquid Crystal Alignment Agent In the solution containing polymer (PI-23) obtained in Synthesis Example 23, a solution containing polymer (PI-21) obtained in Synthesis Example 21 was added in a mass ratio of polymer (PI-23): polymer (PI-21) = 70:30 based on solid content. Then, an additive (AD-2) of 3 parts by mass relative to a total of 100 parts by mass of polymer (PI-23) and polymer (PI-21) was added. The solution was diluted with NMP and butyl cellosolve (BC) to prepare a solution with a solvent composition of NMP / BC = 80 / 20 (mass ratio) and a solid content concentration of 3.5% by mass. The solution was filtered using a filter with a pore size of 0.2 μm to prepare the liquid crystal alignment agent (AL-1).

[0096] 2. Preparation for manufacturing an FFS-type liquid crystal cell using photoalignment: A glass substrate (designated as the first substrate) having a flat plate electrode (bottom electrode), an insulating layer, and a comb-shaped electrode (top electrode) sequentially deposited on one side, and a glass substrate without electrodes (designated as the second substrate). Then, a liquid crystal alignment agent (AL-1) is applied to the electrode forming surface of the first substrate and one side of the second substrate using a spin coater, and heated (pre-baked) at 80°C for 1 minute using a hot plate. Subsequently, it is dried (post-baked) for 30 minutes in a 230°C oven where the chamber has been purged with nitrogen, forming a coating with an average film thickness of 0.1 μm. Photoalignment is performed by irradiating the obtained coating with 1,000 J / m² of ultraviolet light containing a linearly polarized 254 nm bright line from the substrate normal direction using an Hg-Xe lamp. Furthermore, the irradiation amount is a value measured using a photometer with a wavelength of 254 nm as a reference. Next, the photo-aligned coating was heat-treated in a clean oven at 230°C for 30 minutes to form a liquid crystal alignment film. Then, for one of the pair of substrates with the liquid crystal alignment film, an epoxy resin adhesive containing 3.5 μm diameter alumina spheres was screen-printed onto the outer edge of the surface with the liquid crystal alignment film. Subsequently, the substrates were overlapped and pressed together so that the projection direction of the polarization axis on the substrate surface during light irradiation was antiparallel, and the adhesive was heat-cured at 150°C for 1 hour. Then, negative liquid crystal (Merck, MLC-6608) was filled between the pair of substrates through the liquid crystal injection port, and the injection port was sealed with an epoxy adhesive to obtain a photo-FFS type liquid crystal cell. Finally, to remove the flow alignment during liquid crystal injection, it was heated at 120°C and then slowly cooled to room temperature. In addition, the series of operations were performed by varying the amount of ultraviolet irradiation after baking within the range of 100 J / m² to 10,000 J / m², thereby producing three or more liquid crystal cells with different amounts of ultraviolet irradiation. The liquid crystal cell with the exposure amount (optimal exposure amount) that showed the best alignment characteristics was evaluated.

[0097] 3. Evaluation (1) Evaluation of charge accumulation characteristics (high-temperature short-term image retention) The liquid crystal cell manufactured in step 2 was placed in an environment of 60°C and 1 atmosphere. Using an AC rectangular wave (Alternating Current, AC) with a frequency of 30 Hz, the cell was driven with a relative transmittance of 100% and the brightness difference between any two pixels was set to 0. AC driving was performed under a backlight of 5000 cd / m², while a DC 0.1 V was applied to a single pixel for 60 minutes to accumulate charge. When the DC 0.1 V application ended and the cell was driven back to AC with a relative transmittance of 50%, a brightness difference ΔL was generated between the two pixels due to the accumulated charge. Furthermore, the smaller the brightness difference, the more difficult it is to accumulate charge at high temperatures, and the better the high-temperature short-term image retention characteristics. The value obtained by dividing the brightness difference ΔL by the average brightness of the two pixels is less than 1% and is set as "Very Good (◎)"; the value is 1% or more but less than 2% and is set as "Good (○)"; the value is 2% or more but less than 3% and is set as "Acceptable (△)"; and the value is 3% or more and is set as "Poor (×)". In this embodiment, the result is an evaluation of "Very Good (◎)".

[0098] (2) Evaluation of image retention characteristics (long-term image retention) The liquid crystal cell manufactured in step 2. was placed in an environment of 25°C and 1 atmosphere. A 30 Hz AC rectangular wave was used to drive the image with 100% relative transmittance. After setting the brightness difference between any two pixels to 0, AC driving was performed under backlight illumination of 5000 cd / m², while a 0.5 V DC was applied to a single pixel for 60 minutes to accumulate charge. When the application of 0.5 V DC ended and the image was driven back to AC with 50% relative transmittance, a brightness difference ΔL was generated between the two pixels due to the accumulated charge. The change in brightness difference ΔL over time was observed, and the time from the end of the application of 0.5 V DC until the brightness difference ΔL reached less than 36.8% of its initial value was defined as the image retention time. Furthermore, the shorter the time, the easier it is for the image retention caused by the accumulated charge to disappear, indicating better long-term image retention characteristics at room temperature. Regarding the evaluation, a case where the afterimage removal time is less than 10 minutes is defined as "Very Good (◎)", a case where it is more than 10 minutes but less than 20 minutes is defined as "Good (○)", a case where it is more than 20 minutes but less than 30 minutes is defined as "Acceptable (△)", and a case where it is more than 30 minutes is defined as "Poor (×)". The result in this embodiment is an evaluation of "Very Good (◎)".

[0099] (3) Evaluation of Emerging Bright Spots The liquid crystal cell manufactured in step 2 was observed using a polarizing microscope (ECLIPSE E600WPOL) (manufactured by Nikon Corporation), and the bright spots (emerging bright spots) were evaluated. Specifically, the liquid crystal cell was placed between two polarizing plates arranged orthogonally to the polarizing axes, and the liquid crystal cell was observed using a polarizing microscope with a magnification of 5x (observation area: approximately 2500 μm × 2500 μm). The fewer the number of bright spots, the less the generation of highly crystalline thermal decomposition products or photodecomposition products, which can be said to be better. The case with fewer than 10 bright spots was defined as "excellent (◎)", the case with more than 10 but less than 50 bright spots was defined as "good (○)", the case with more than 50 but less than 100 bright spots was defined as "acceptable (△)", and the case with more than 100 bright spots was defined as "poor (×)". As a result, the evaluation in the above embodiment was "excellent (◎)".

[0100] (4) Evaluation of the mechanical properties of the film: The liquid crystal alignment agent (AL-1) prepared in step 1 was coated onto a glass substrate using a spin coater and heated (pre-baked) for 3 minutes using a hot plate at 110°C. Subsequently, it was dried (post-baked) for 30 minutes in an oven at 230°C with nitrogen purging to form a coating with an average thickness of 0.08 μm, and the haze value of the coating was measured using a haze meter. Then, the coating was subjected to five rubbing treatments using a friction machine with a roller wound with cotton cloth, at a roller speed of 1000 rpm, a platform movement speed of 3 cm / s, and a bristle indentation length of 0.3 mm. Subsequently, the haze value of the liquid crystal alignment film was measured using a haze meter, and the difference between the haze value and the haze value before the rubbing treatment (haze change value) was calculated. With the haze value of the film before rubbing treatment set as Hz1 (%) and the haze value of the film after rubbing treatment set as Hz2 (%), the haze change value is expressed by the following formula (z-2): Haze change value (%) = Hz2 - Hz1 … (z-2) A haze change value of less than 0.5 for the liquid crystal alignment film is evaluated as "Excellent (◎)", a haze change value of 0.5 or more but less than 0.8 is evaluated as "Good (○)", a haze change value of 0.8 or more but less than 1.0 is evaluated as "Acceptable (△)", and a haze change value of 1.0 or more is evaluated as "Poor (×)". If the haze change value is less than 1.0, it can be said that the film strength is sufficiently high and the rubbing resistance is high, that is, the mechanical properties of the film are good. As a result, in the above embodiment, the film strength is evaluated as "Excellent (◎)".

[0101] (5) Evaluation of transmittance: The liquid crystal alignment agent (AL-1) prepared in step 1 was coated onto a quartz substrate using a spin coater. After heating on a hot plate at 80°C for 1 minute, it was heated for 30 minutes in an oven at 230°C with nitrogen purging to form a coating with an average thickness of 100 nm. For the quartz substrate with the coating, the absorption spectrum in the ultraviolet-visible region was measured using a UV-Vis near-infrared spectrophotometer (manufactured by Nippon Spectrophotometer Co., Ltd., product name "V-670") with a quartz substrate of the same type without the coating as a reference. In addition, the incident angle to the substrate was set to Brewster's angle using a polarizing filter and P-polarized light to suppress the effect caused by reflection. A transmittance of 98% or higher at a wavelength of 400 nm is defined as "Excellent (◎)", 95% or higher but less than 98% is defined as "Good (○)", 90% or higher but less than 95% is defined as "Acceptable (△)", and less than 90% is defined as "Poor (×)". In this embodiment, the result is evaluated as "Excellent (◎)".

[0102] [Examples 2, 4, 5, 9, 10, 12-14, 16, 19, 21 and Comparative Examples 1, 2, 4, 6] The composition of the liquid crystal alignment agent was changed as shown in Table 3. Otherwise, the liquid crystal alignment agent was prepared in the same manner as in Example 1. Furthermore, using the obtained liquid crystal alignment agent, optical FFS-type liquid crystal cells were manufactured in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 3.

[0103] [Example 3] 1. Preparation of liquid crystal alignment agent: NMP and butyl cellosolve (BC) were added to the solution containing polymer (PI-28) obtained in Synthesis Example 28 to prepare a solution with a solvent composition of NMP / BC = 80 / 20 (mass ratio) and a solid content concentration of 3.5% by mass. The solution was filtered using a filter with a pore size of 0.2 μm to prepare the liquid crystal alignment agent (AL-3).

[0104] 2. The preparation of the first and second substrates for manufacturing the FFS-type liquid crystal cell using the friction method is the same as in Example 1. Then, a liquid crystal alignment agent (AL-3) is applied to the electrode forming surface of the first substrate and one side of the second substrate using a spin coater, and heated (pre-baked) for 3 minutes using a hot plate at 110°C. Subsequently, it is dried (post-baked) for 30 minutes in an oven at 230°C with nitrogen purging, forming a coating with an average film thickness of 0.08 μm. Next, the coating surface is rubbed using a friction machine with rollers wound with rayon cloth, at a roller speed of 1000 rpm, a platform movement speed of 3 cm / s, and a bristle indentation length of 0.3 mm. Afterward, it is ultrasonically cleaned in ultrapure water for 1 minute, and then dried in a clean oven at 100°C for 10 minutes, thereby obtaining a pair of substrates with a liquid crystal alignment film. Next, for a pair of substrates with a liquid crystal alignment film, a liquid crystal injection port remains at the edge of the surface where the liquid crystal alignment film is formed. An epoxy resin adhesive containing alumina spheres with a diameter of 3.5 μm is then screen-printed onto the port. The substrates are then overlapped and pressed together, and the adhesive is thermo-cured at 150°C for 1 hour. Then, negative liquid crystal (manufactured by Merck, MLC-6608) is filled into the gap between the two substrates through the injection port, and the injection port is sealed using an epoxy adhesive. Furthermore, to remove the flow alignment during liquid crystal injection, the liquid crystal is heated at 120°C and then slowly cooled to room temperature to manufacture a liquid crystal cell (a triboelectric FFS type liquid crystal cell). In addition, when the pair of substrates are overlapped, the rubbing directions of each substrate are made antiparallel.

[0105] 3. The liquid crystal alignment agent prepared in 1. and the liquid crystal cell manufactured in 2. were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 3.

[0106] [Examples 6-8, 11, 15, 17, 18, 20 and Comparative Examples 3, 5, 7, 8] The composition of the liquid crystal alignment agent was changed as shown in Table 3, except that the liquid crystal alignment agent was prepared in the same manner as in Example 3. Furthermore, using the obtained liquid crystal alignment agent, a tactile FFS type liquid crystal cell was manufactured in the same manner as in Example 3, and various evaluations were performed. The evaluation results are shown in Table 3.

[0107] [Table 3] Liquid crystal alignment agent Orientation treatment evaluate Alignment agent name Polymer 1 Polymer 2 Polymer 3 additive afterimage Emerging highlights Mechanical properties Transmission rate type mass ratio type mass ratio type mass ratio type mass ratio High temperature short-term long Example 1 AL-1 PI-23 70 PI-21 30 AD-2 3 Light ◎ ◎ ◎ ◎ ◎ Example 2 AL-2 PI-24 100 Light ◎ ◎ ◎ ○ ◎ Example 3 AL-3 PI-28 100 friction ◎ ◎ ◎ ○ ◎ Example 4 AL-4 PI-25 10 PI-1 90 AD-1 1 Light ◎ ◎ ◎ ◎ ◎ Example 5 AL-5 PI-27 30 PI-2 70 AD-6 3 Light ◎ ◎ ◎ ◎ ○ Example 6 AL-6 PI-28 30 PI-3 70 friction ◎ ◎ ◎ ○ ○ Example 7 AL-7 PI-28 50 PI-4 50 friction ◎ ◎ ◎ ○ ○ Example 8 AL-8 PI-23 20 PI-5 80 friction ◎ ◎ ◎ ○ ◎ Example 9 AL-9 PI-25 10 PI-6 90 AD-2 5 Light ◎ ◎ ◎ ◎ ◎ Example 10 AL-10 PI-25 50 PI-7 50 Light ○ ◎ ◎ ○ ○ Example 11 AL-11 PI-29 70 PI-8 30 friction ○ ◎ ◎ ○ ○ Example 12 AL-12 PI-25 20 PI-9 60 PI-21 20 Light ○ ◎ ◎ ○ ○ Example 13 AL-13 PI-25 20 PI-10 80 Light ◎ ◎ ◎ ○ ○ Example 14 AL-14 PI-27 40 PI-11 60 Light ◎ ◎ ◎ ◎ ◎ Example 15 AL-15 PI-27 30 PI-12 70 friction ◎ ◎ ◎ ◎ ◎ Example 16 AL-16 PI-25 15 PI-13 85 AD-3 10 Light ◎ ◎ ◎ ◎ ◎ Example 17 AL-17 PI-23 20 PI-14 80 friction ◎ ◎ ◎ ○ ◎ Example 18 AL-18 PI-24 50 PI-15 30 PI-22 20 AD-3 3 friction ◎ ◎ ◎ ◎ ◎ Example 19 AL-19 PI-27 20 PI-36 80 Light ◎ ◎ ◎ ○ ◎ Example 20 AL-20 PI-29 50 PI-37 50 friction ○ ◎ ◎ ○ ○ Example 21 AL-21 PI-25 70 PI-38 30 Light ◎ ◎ ◎ ◎ ○ Comparative Example 1 AL-22 PI-25 70 PI-21 30 Light ◎ × ◎ ○ ◎ Comparative Example 2 AL-23 PI-26 100 Light × ◎ × × × Comparative Example 3 AL-24 PI-29 100 friction ◎ × ◎ ○ ◎ Comparative Example 4 AL-25 PI-25 20 PI-16 80 Light ◎ ◎ × × ◎ Comparative Example 5 AL-26 PI-26 30 PI-17 70 friction × ◎ × × × Comparative Example 6 AL-27 PI-25 30 PI-18 70 Light × ◎ × ○ × Comparative Example 7 AL-28 PI-27 50 PI-19 50 AD-3 3 friction ◎ ◎ × ◎ × Comparative Example 8 AL-29 PI-29 20 PI-20 80 friction ◎ × △ ○ ◎

[0108] • PSA type liquid crystal display element [Example 22] 1. Preparation of liquid crystal alignment agent In the solution containing polymer (PI-32) obtained in Synthesis Example 32, 5 parts by mass of additive (AD-4) relative to 100 parts by mass of polymer (PI-32) were added, and the solution was diluted with NMP and BC to prepare a solution with a solvent composition of NMP / BC = 50 / 50 (mass ratio) and a solid component concentration of 3.5% by mass. The solution was filtered using a filter with a pore size of 0.2 μm, thereby preparing liquid crystal alignment agent (AL-30).

[0109] 2. Manufacturing of PSA-type liquid crystal cells (1) Preparation of liquid crystal composition: 10 g of nematic liquid crystal (Merck, MLC-6608) was mixed with 5% by mass of the liquid crystal compound represented by the following formula (L1-1) and 0.3% by mass of the photopolymerizable compound represented by the following formula (L2-1) to obtain liquid crystal composition LC1. [Chemical 21]

[0110] (2) Manufacturing of the liquid crystal cell: The prepared liquid crystal alignment agent (AL-30) is coated onto the transparent electrode surface of a glass substrate with a transparent electrode containing an ITO film using a spin coater. After pre-baking on a hot plate at 80°C for 1 minute, the solvent is removed by heating at 200°C for 1 hour in an oven filled with nitrogen, thereby forming a coating film (liquid crystal alignment film) with a thickness of 0.08 μm. The coating film is then rubbed using a friction machine with a roller wound with rayon cloth, at a roller speed of 400 rpm, a platform movement speed of 3 cm / s, and a bristle indentation length of 0.1 mm. Subsequently, it is ultrasonically cleaned in ultrapure water for 1 minute, and then dried in a clean oven at 100°C for 10 minutes, thereby obtaining a substrate with a liquid crystal alignment film. The above operation is repeated to obtain a pair (two) substrates with liquid crystal alignment films. Furthermore, the rubbing treatment is a weak rubbing treatment performed for the purpose of controlling the collapse of the liquid crystal and performing alignment separation by a simple method. After applying an epoxy resin adhesive containing 3.5 μm diameter alumina spheres via screen printing to the outer periphery of the surface of one substrate with a liquid crystal alignment film, the liquid crystal alignment films of a pair of substrates are overlapped and pressed together, and the adhesive is thermosetting at 150°C for 1 hour. Then, a liquid crystal composition LC1 is filled into the gaps between the substrates through a liquid crystal injection port, and the injection port is sealed with an epoxy adhesive. To remove flow alignment during liquid crystal injection, the mixture is heated at 150°C for 10 minutes and then slowly cooled to room temperature. Next, the obtained liquid crystal cell is irradiated with ultraviolet light at a dose of 50,000 J / m² using an ultraviolet irradiation device with a metal halide lamp as the light source, under liquid crystal driving conditions with an AC 10 V frequency of 60 Hz applied between the electrodes. This irradiation dose is measured using a photometer with a wavelength of 365 nm as the reference. Thus, a PSA-type liquid crystal cell is manufactured.

[0111] 3. The liquid crystal alignment agent prepared in 1. and the liquid crystal cell manufactured in 2. were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 4.

[0112] [Examples 23-26 and Comparative Examples 9-12] The composition of the liquid crystal alignment agent was changed as shown in Table 4. Otherwise, the liquid crystal alignment agent was prepared in the same manner as in Example 22. Furthermore, using the obtained liquid crystal alignment agent, a PSA-type liquid crystal cell was manufactured in the same manner as in Example 22, and various evaluations were performed. The evaluation results are shown in Table 4.

[0113] [Table 4] Liquid crystal alignment agent evaluate Alignment agent name Polymer 1 Polymer 2 additive afterimage Emerging highlights Mechanical properties Transmission rate type mass ratio type mass ratio type mass ratio short term long Example 22 AL-30 PI-32 100 AD-4 5 ◎ ◎ ◎ ◎ ◎ Example 23 AL-31 PI-32 30 PI-30 70 AD-1 2 ◎ ◎ ◎ ◎ ◎ Example 24 AL-32 PI-32 60 PI-34 40 ◎ ◎ ◎ ○ ◎ Example 25 AL-33 PSQ-1 10 PI-31 90 AD-5 10 ◎ ◎ ◎ ◎ ◎ Example 26 AL-34 MI-2 20 PI-11 80 ◎ ◎ ◎ ○ ◎ Comparative Example 9 AL-35 PI-35 100 × ◎ × ○ × Comparative Example 10 AL-36 PI-35 30 PI-33 70 AD-5 5 × ◎ × ◎ × Comparative Example 11 AL-37 PSQ-1 10 PI-34 90 ◎ × ◎ ○ ◎ Comparative Example 12 AL-38 MI-2 20 PI-20 80 ◎ × △ ○ ◎

[0114] • Vertical-position liquid crystal display element [Example 27] 1. Preparation of liquid crystal alignment agent In the solution containing polymer (PI-1) obtained in Synthesis Example 1, polymer (MI-1) obtained in Synthesis Example 40 was added in such a way that, based on the conversion of solid content, polymer (MI-1) is 10 parts by mass relative to 90 parts by mass of polymer (PI-1). The solution was diluted with NMP and BC to prepare a solution with a solvent composition of NMP / BC = 80 / 20 (mass ratio) and a solid content concentration of 3.5% by mass. The solution was filtered using a filter with a pore size of 0.2 μm to prepare liquid crystal alignment agent (AL-39).

[0115] 2. Fabrication of the vertically aligned liquid crystal cell (UV2A): The liquid crystal alignment agent (AL-39) prepared in step 1 is coated onto the transparent electrode surface of a glass substrate with a transparent electrode containing an ITO film using a spin coater, and pre-baked for 1 minute using a hot plate at 80°C. Subsequently, a coating with a thickness of 0.1 μm is formed by heating at 230°C for 1 hour in an oven with nitrogen purging. Then, the surface of the coating is irradiated with 1,000 J / m² of polarized ultraviolet light containing a bright line of 313 nm from a direction tilted at 40° relative to the substrate normal using an Hg-Xe lamp and a Glan-Taylor prism to impart liquid crystal alignment capability. The same operation is repeated to fabricate a pair (two) substrates with liquid crystal alignment films. After applying an epoxy resin adhesive containing 3.5 μm diameter alumina spheres via screen printing to the outer periphery of the liquid crystal alignment film surface of one substrate, the liquid crystal alignment film surfaces of the two substrates are faced together and pressed together with the projection directions of the ultraviolet light axes of each substrate onto the substrate surface antiparallel. The adhesive is then thermosetting at 150°C for 1 hour. Subsequently, negative liquid crystal (manufactured by Merck, MLC-6608) is filled into the gap between the substrates through the liquid crystal injection port, and the liquid crystal injection port is sealed using an epoxy adhesive. Furthermore, to remove the flow alignment during liquid crystal injection, it is heated at 130°C and then slowly cooled to room temperature.

[0116] 3. The liquid crystal alignment agent prepared in 1. and the liquid crystal cell manufactured in 2. were evaluated in the same manner as in Example 1. The evaluation results are shown in Table 5.

[0117] [Example 28 and Comparative Examples 13, 14] The composition of the liquid crystal alignment agent was changed as shown in Table 5, and the liquid crystal alignment agent was prepared in the same manner as in Example 27. Furthermore, using the obtained liquid crystal alignment agent, a vertically aligned liquid crystal cell was manufactured in the same manner as in Example 27, and various evaluations were performed. The evaluation results are shown in Table 5.

[0118] [Table 5] Liquid crystal alignment agent evaluate Alignment agent name Polymer 1 Polymer 2 additive afterimage Emerging highlights Mechanical properties Transmission rate type mass ratio type mass ratio type mass ratio short term long Example 27 AL-39 MI-1 10 PI-1 90 ◎ ◎ ◎ ○ ◎ Example 28 AL-40 MI-1 30 PI-2 70 AD-7 5 ◎ ◎ ◎ ◎ ○ Comparative Example 13 AL-41 MI-1 10 PI-16 90 ◎ ◎ × × ◎ Comparative Example 14 AL-42 MI-1 30 PI-19 70 AD-7 5 ◎ ◎ × ◎ ×

[0119] Based on the above results, it is clear that by using a liquid crystal alignment agent containing a polymer (P), a liquid crystal alignment film with high mechanical strength can be formed, and a liquid crystal element with high transmittance that is not prone to image retention and bright spots can be obtained.

Claims

1. A liquid crystal alignment agent comprising a polymer (P) having a structural unit derived from a compound represented by the following formula (1), said polymer (P) being at least one selected from the group consisting of polyamide, polyamide ester and polyimide; wherein, in formula (1), Ar1 is a divalent aromatic cyclic group; X1 is a single bond, -O-, -S- or -NR1-; R1 is a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a thermally detachable group; Ar2, Ar3 and Y1 satisfy the following requirements (i), (ii) or (iii); wherein, When X1 is a single bond, Y1 is bonded to Ar1 through a carbon atom; (i) Ar2 is a divalent aromatic cyclic group; Ar3 is a monovalent aromatic cyclic group; Y1 is a divalent organic group with more than one carbon atom; (ii) Ar2 and Ar3 represent nitrogen-containing aromatic fused ring structures formed together with nitrogen atoms bonded to Ar2 and Ar3; Y1 is a divalent organic group with more than one carbon atom; (iii) Ar2 is a divalent aromatic cyclic group; Ar3 and Y1 are divalent groups that contain nitrogen-containing aromatic fused ring structures formed together with nitrogen atoms bonded to Ar3 and Y1.

2. The liquid crystal alignment agent as claimed in claim 1, wherein X1 in formula (1) is -O-, -S- or -NR1-; or X1 is a single bond and part or all of Y1 is a chain structure, and Y1 is bonded to Ar1 through the chain structure.

3. The liquid crystal alignment agent as claimed in claim 1, wherein Y1 in formula (1) is a divalent organic group with 1 or more carbon atoms, is partially or entirely chain-like, and is bonded to nitrogen atoms bonded to Ar3 through the chain-like structure.

4. The liquid crystal alignment agent as claimed in claim 1 further comprises a polymer (Q) that does not have structural units derived from the compound represented by formula (1).

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

6. A liquid crystal alignment film formed using a liquid crystal alignment agent as described in any one of claims 1 to 5.

7. A liquid crystal element comprising a liquid crystal alignment film as described in claim 6.