WO2024157869A1

WO2024157869A1 - Liquid crystal aligning agent, liquid crystal alignment film, and liquid crystal display element

Info

Publication number: WO2024157869A1
Application number: PCT/JP2024/001238
Authority: WO
Inventors: 雅倫尹
Original assignee: 日産化学株式会社
Priority date: 2023-01-23
Filing date: 2024-01-18
Publication date: 2024-08-02
Also published as: TW202436600A

Abstract

Provided is a liquid crystal alignment film that suppresses the formation of AC afterimages even when the amount of photoirradiation in an alignment treatment by a photoalignment method is small. Also provided is a liquid crystal alignment film in which the amount of fluctuation (nonuniformity) in the twist angle of a liquid crystal molecule in the plane of the liquid crystal alignment film can be reduced.　The liquid crystal aligning agent contains at least one polymer (P) selected from the group consisting of a polyimide precursor produced by using a tetracarboxylic acid component and a diamine component and an polyimide that is an imidized product of the polyimide precursor, in which the tetracarboxylic acid component comprises at least one component selected from the group consisting of a tetracarboxylic acid dianhydride represented by formula (T1) and derivatives thereof and at least one component selected from the group consisting of tetracarboxylic acid dianhydrides represented by formulae (T2-1) to (T2-3) and derivatives thereof. (In the formulae, the meaning of each symbol is as defined in the description.)

Description

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

The present invention relates to a liquid crystal alignment agent, a liquid crystal alignment film, and a liquid crystal display element.

Liquid crystal display elements are widely used as display units for personal computers, mobile phones, smartphones, televisions, etc. Liquid crystal display elements include, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, pixel electrodes and a common electrode that apply an electric field to the liquid crystal layer, a liquid crystal alignment film that controls the liquid crystal orientation of the liquid crystal molecules in the liquid crystal layer, and thin film transistors (TFTs) that switch the electrical signals supplied to the pixel electrodes. Known methods for driving liquid crystal molecules include vertical electric field methods such as the TN (Twisted Nematic) method and the VA (Vertical Alignment) method, and horizontal electric field methods such as the IPS (In-Plane Switching) method and the FFS (Fringe Field Switching) method. The horizontal electric field method, in which electrodes are formed on only one side of the substrate and an electric field is applied parallel to the substrate, is known as a liquid crystal display element that has a wider viewing angle characteristic and is capable of high-quality display compared to the conventional vertical electric field method, in which a voltage is applied to electrodes formed on the top and bottom substrates to drive the liquid crystal.

The most widely used liquid crystal alignment film in industry is produced by rubbing the surface of a film made of polyamic acid and/or polyimide formed by imidizing polyamic acid on an electrode substrate in one direction with a cloth such as cotton, nylon, or polyester. Rubbing is a simple and highly productive industrially useful method. However, as liquid crystal display elements become more powerful, more precise, and larger, various problems have become evident, such as scratches on the surface of the alignment film caused by rubbing, dust generation, effects of mechanical force and static electricity, and even non-uniformity within the alignment treatment surface. As an alternative alignment treatment method to rubbing, a photoalignment method is known in which liquid crystal alignment ability is imparted by irradiating polarized radiation. As for photoalignment methods, methods using photoisomerization reactions, photocrosslinking reactions, photodecomposition reactions, etc. have been proposed (see, for example, Non-Patent Document 1 and Patent Documents 1-3).

Japanese Patent Application Publication No. 9-297313 JP 2004-206091 A WO2018/117240 publication

The liquid crystal alignment film used in the liquid crystal display element of the IPS driving method or FFS driving method requires a high alignment control force to suppress the afterimage caused by long-term AC driving (hereinafter, also referred to as AC afterimage). In addition, when performing alignment treatment by a photo-alignment method, the amount of light irradiation is a factor that affects energy costs and production speed, so it is preferable to be able to perform alignment treatment with a small amount of light irradiation.
However, the inventors have found that it is difficult for conventional liquid crystal alignment films to achieve a high level of both suppression of AC image retention and suppression of variation (non-uniformity) in the twist angle of liquid crystal molecules within the liquid crystal alignment film. This increases the risk of AC image retention occurring when driving the liquid crystal, and also increases the risk that a liquid crystal display element with excellent contrast and high display quality cannot be obtained because the liquid crystal alignment becomes incomplete in part of the liquid crystal alignment film when the liquid crystal display element is enlarged.

In view of the above circumstances, the object of the present invention is to provide a liquid crystal alignment agent capable of obtaining a liquid crystal alignment film that suppresses AC afterimages even when the amount of light irradiation in the alignment treatment by the photo-alignment method is small, the liquid crystal alignment film, and a liquid crystal display element using the liquid crystal alignment film. It is also to provide a liquid crystal alignment agent capable of obtaining a liquid crystal alignment film that can reduce the variation (non-uniformity) of the twist angle of the liquid crystal molecules within the liquid crystal alignment film plane, the liquid crystal alignment film, and a liquid crystal display element using the liquid crystal alignment film.

The present inventors have conducted various studies to achieve the above object, and have found that the use of a specific tetracarboxylic acid component is effective for achieving the above object. They have also found that a liquid crystal aligning agent having the following composition is optimal for achieving the above object, and have completed the present invention.
Thus, the present invention is based on the above findings and has the following gist.
At least one selected from the group consisting of tetracarboxylic dianhydrides represented by the following formula (T1) and derivatives thereof;
a tetracarboxylic acid component comprising at least one selected from the group consisting of tetracarboxylic acid dianhydrides and derivatives thereof represented by the following formulas (T2-1) to (T2-3);
A liquid crystal aligning agent comprising: a diamine component; and at least one polymer (P) selected from the group consisting of a polyimide precursor obtained by using the diamine component and a polyimide which is an imidized product of the polyimide precursor.

(R ¹ to R ⁴ each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and at least one of R ¹ to R ⁴ represents a group other than a hydrogen atom as defined above.)
Throughout the present specification, examples of halogen atoms include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and * represents a bond. Boc represents a tert-butoxycarbonyl group.

By using the liquid crystal aligning agent of the present invention, a liquid crystal alignment film that suppresses AC afterimages can be obtained even when the amount of light irradiation in the alignment treatment by the photoalignment method is small. In addition, a liquid crystal alignment film that can reduce the variation (non-uniformity) of the twist angle of liquid crystal molecules in the liquid crystal alignment film plane can be obtained.
The mechanism by which the above-mentioned effects of the present invention are obtained is not entirely clear, but the following is thought to be one of the reasons.
First, by introducing a structural unit that is not easily decomposed by light irradiation, the amount of decomposition products generated in the alignment treatment film when irradiated with polarized ultraviolet light is suppressed. Therefore, the resulting liquid crystal alignment film has improved interaction with the liquid crystal molecules, so that it is possible to obtain a liquid crystal alignment film with small variation (non-uniformity) in the twist angle of the liquid crystal molecules in the liquid crystal alignment film plane and suppressed AC afterimages.
In addition, the tetracarboxylic dianhydride and its derivatives represented by the above formula (T2-1) have multiple cyclohexane structures in the molecule, and therefore, compared to conventional tetracarboxylic acid derivatives having a cyclooctane structure, thermal imidization proceeds more easily, which is believed to be why the liquid crystal alignment can be improved and the above-mentioned effects are achieved.
Furthermore, it is considered that the tetracarboxylic dianhydrides and derivatives thereof represented by the above formulas (T2-2) and (T2-3) have a larger three-dimensional structure and a stronger interaction with liquid crystal molecules than conventional tetracarboxylic acid derivatives having a cyclohexane structure, which is why the above effects are obtained.

1 is a schematic cross-sectional view showing an example of a lateral electric field type liquid crystal display element of the present invention. FIG. 4 is a schematic cross-sectional view showing another example of a lateral electric field type liquid crystal display element of the present invention.

<Polymer (P)>
The liquid crystal aligning agent of the present invention contains at least one polymer (P) selected from the group consisting of a polyimide precursor obtained by using a tetracarboxylic acid component consisting of at least one selected from the group consisting of tetracarboxylic acid dianhydrides represented by the above formula (T1) and derivatives thereof (also referred to as a specific alicyclic tetracarboxylic acid derivative (p1) in the present invention) and at least one selected from the group consisting of tetracarboxylic acid dianhydrides represented by the above formulas (T2-1) to (T2-3) and derivatives thereof (also referred to as a specific alicyclic tetracarboxylic acid derivative (p2) in the present invention), and a diamine component. The polymer (P) may be one or more types.
Here, the polyimide precursor is a polymer that can give a polyimide by imidizing a polyamic acid, a polyamic acid ester, or the like.
(Tetracarboxylic acid component)
The polyamic acid (P') which is a polyimide precursor of the polymer (P) can be obtained, for example, by a polymerization reaction of a diamine component, a tetracarboxylic acid dianhydride corresponding to the specific alicyclic tetracarboxylic acid derivative (p1) and a tetracarboxylic acid dianhydride corresponding to the specific alicyclic tetracarboxylic acid derivative (p2).
In producing the polymer (P), the tetracarboxylic acid component to be reacted with the diamine component may be not only a tetracarboxylic acid dianhydride but also a derivative of a tetracarboxylic acid dianhydride such as a tetracarboxylic acid, a tetracarboxylic acid dihalide, a tetracarboxylic acid dialkyl ester, or a tetracarboxylic acid dialkyl ester dihalide.
Specific examples of the alkyl group having 1 to 6 carbon atoms in R ¹ to R ⁴ in formula (T1) include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, etc. Specific examples of the alkenyl group having 2 to 6 carbon atoms in R ¹ to R ⁴ include a vinyl group, a propenyl group, a butenyl group, etc., which may be linear or branched.
Specific examples of the alkynyl group having 2 to 6 carbon atoms in R ¹ to R ⁴ in formula (T1) include an ethynyl group, a 1-propynyl group, a 2-propynyl group, a 1-butynyl group, a 2-butynyl group, a 3-butynyl group, etc. Examples of the monovalent organic group containing a fluorine atom and having 1 to 6 carbon atoms in R ¹ to R ⁴ in formula (T1) include a fluoromethyl group, a trifluoromethyl group, a pentafluoroethyl group, a pentafluoropropyl group, a trifluoromethoxy group, a 2,2,2-trifluoroethyl group, a 2,2,2-trifluoroethoxy group, etc.
From the viewpoint of high photoreactivity, it is more preferable that at least two of R ¹ to R ⁴ in the above formula (T1) represent a group other than a hydrogen atom as defined above. Also, from the viewpoint of high photoreactivity, it is more preferable that R ¹ and R ⁴ represent a group other than a hydrogen atom, and R ² and R ³ represent a hydrogen atom.
From the viewpoint of high photoreactivity, R ¹ to R ⁴ in the above formula (T1) are each independently a hydrogen atom or a methyl group, more preferably at least one of R ¹ to R ⁴ is a methyl group, and even more preferably at least two of R ¹ to R ⁴ are methyl groups. Most preferably, R ¹ and R ⁴ in the above formula (T1) are methyl groups, and R ² and R ³ are hydrogen atoms.
The proportion of the specific alicyclic tetracarboxylic acid derivative (p1) used is more preferably 50 mol % or more, further preferably 60 mol % or more, and most preferably 70 mol % or more, based on 1 mol of the total tetracarboxylic acid components used in the polymer (P).
The proportion of the specific alicyclic tetracarboxylic acid derivative (p1) used is preferably 95 mol % or less, and more preferably 50 to 95 mol %, per mol of the total tetracarboxylic acid components used in the polymer (P).
The proportion of the specific alicyclic tetracarboxylic acid derivative (p2) used is preferably 5 mol % or more per mol of the total tetracarboxylic acid components used in the polymer (P).
The proportion of the specific alicyclic tetracarboxylic acid derivative (p2) used is preferably 50 mol % or less, more preferably 40 mol % or less, and even more preferably 30 mol % or less, based on 1 mol of the total tetracarboxylic acid components used in the polymer (P).
The diamine component used in the production of the polymer (P) is not particularly limited. Examples of diamines are listed below, but are not limited thereto. The diamines may be used alone, in combination of two or more, or in combination of three or more.
Phenylenediamines such as p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, m-phenylenediamine, 2,4-dimethyl-m-phenylenediamine, 2,5-diaminotoluene, and 2,6-diaminotoluene; 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-dihydroxy-4,4'- diaminobiphenyl compounds such as diaminobiphenyl, 2,2'-difluoro-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 4,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,2'-diaminobiphenyl, and 2,3'-diaminobiphenyl; diamines represented by the following formula (d _AL ) (preferably, diamines represented by the following formulas (d _AL -1) to (d _AL 1,7-bis(4-aminophenoxy)heptane, 1,7-bis(3-aminophenoxy)heptane, 1,8-bis(4-aminophenoxy)octane, 1,8-bis(3-aminophenoxy)octane, 1,9-bis(4-aminophenoxy)nonane, 1,9-bis(3-aminophenoxy)nonane, 1,10-bis(4-aminophenoxy)decane, 1,10-bis(3-aminophenoxy)decane, 1,11-bis(4-aminophenoxy)undecane, 1,11-bis(3-aminophenoxy)undecane, 1,12-bis(4-aminophenoxy)dodecane, 1,12-bis(3-aminophenoxy)dodecane, 1,2-bis(6-aminophenoxy)dodecane, 1,2-bis(6-amino-2-naphthyl)ethane, or 6-[2-(4-aminophenoxy)ethoxy]-2-naphthylamine. ), 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-bis(4-aminophenoxy)diphenyl ether, 1,4-bis[4-(4-aminophenoxy)phenoxy]benzene, and other diamines having a diphenyl ether structure (hereinafter, these are collectively referred to as the first diamine). ); diamines having a tetracarboxylic diimide structure such as N,N'-bis(4-aminophenyl)-cyclobutane-(1,2,3,4)-tetracarboxylic diimide, N,N'-bis(4-aminophenyl)-1,3-dimethylcyclobutane-(1,2,3,4)-tetracarboxylic diimide, and N,N'-bis(2,2'-bis(trifluoromethyl)-4'-amino-1,1'-biphenyl-4-yl)-cyclobutane-(1,2,3,4)-tetracarboxylic diimide; aromatic diamines having an azobenzene structure such as 4,4'-diaminoazobenzene, and aromatic diamines having a stilbene structure such as 4,4'-diaminostilbene. aromatic diamines having a tolan structure such as diaminotlan; aromatic diamines having a chalcone structure such as 4,4'-diaminochalcone; aromatic diamines having a phenylbenzoate structure such as 1,4-phenylene bis(4-aminobenzoate), 1,4-phenylene bis(3-aminobenzoate), 1,3-phenylene bis(4-aminobenzoate), 1,3-phenylene bis(3-aminobenzoate), bis(4-aminophenyl)terephthalate, bis(3-aminophenyl)terephthalate, bis(4-aminophenyl)isophthalate, and bis(3-aminophenyl)isophthalate; 3-(4-aminophenyl)acrylate, (E)-4-amino-2-methylphenyl 3-(4-aminophenyl)acrylate, (E)-4-aminophenethyl 3-(4-aminophenyl)acrylate, (E,E)-bis-(4'-aminophenyl) 1,3-benzenediacrylate, (E,E)-bis-(4'-aminophenyl) 1,4-benzenediacrylate, or 4-aminophenyl Diamines having a photoalignment group, such as aromatic diamines having a cinnamate structure, such as (2E)-3-(4-aminophenyl)-2-methyl-2-propenoate; diamines having a photopolymerizable group at the end, such as 2-(2,4-diaminophenoxy)ethyl methacrylate or 2,4-diamino-N,N-diallylaniline; 1-(4-(2-(2,4-diaminophenoxy)ethoxy)phenyl)-2-hydroxy-2-methylpropanone, 2-(4-(2-hydroxy-2-methylpropanoyl)phenoxy)ethyl Diamines having a radical polymerization initiator function such as 3,5-diaminobenzoate; diamines having an amide bond such as 4,4'-diaminobenzanilide; diamines having a urea bond such as 1,3-bis(4-aminophenyl)urea, 1,3-bis(4-aminobenzyl)urea, and 1,3-bis(4-aminophenethyl)urea; 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, phenyl)propane, 2,2-bis(3-aminophenyl)propane, 2,2-bis(3-amino-4-methylphenyl)propane, 4,4'-diaminobenzophenone, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-aminobenzyl)benzene; 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 1,4-bis-(4-aminophenyl)-piperazine, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, N-[3-(1H-imidazol-1-yl)propyl] At least one nitrogen atom-containing structure (hereinafter also referred to as a specific nitrogen atom-containing structure) selected from the group consisting of a nitrogen atom-containing heterocycle, a secondary amino group, and a tertiary amino group, represented by 3,5-diaminobenzamide, 4-[4-[(4-aminophenoxy)methyl]-4,5-dihydro-4-methyl-2-oxazolyl]-benzeneamine, or a diamine represented by the following formula (z-1) to formula (z-13), or a diamine having a diphenylamine structure such as 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenyl-N-methylamine, a diamine represented by the following formula (z-14), N,N'-bis(4-aminophenyl)-benzidine, N,N'-bis(4-aminophenyl)-N,N'-dimethylbenzidine, or N,N'-bis(4-aminophenyl)-N,N'-dimethyl-1,4-benzenediamine. However, the specific nitrogen atom-containing structure is an atomic group other than the two amino groups involved in the polycondensation reaction.) (provided that the molecule does not have an amino group to which a protecting group that is detached by heating and replaced with a hydrogen atom is bonded); 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, 4,4'-diamino-3,3'-dihydroxybiphenyl; 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, 4,4'-diaminobiphenyl-3-carboxylic acid, 4,4'-diaminodiphenylmethane-3-carboxylic acid, 1,2-bis(4-aminophenyl)ethane-3-carboxylic acid, 4,4'-diaminobiphenyl-3,3'-dicarboxylic acid, 4,4'-diaminobiphenyl Diamines having a carboxy group such as phenyl-2,2'-dicarboxylic acid, 3,3'-diaminobiphenyl-4,4'-dicarboxylic acid, 3,3'-diaminobiphenyl-2,4'-dicarboxylic acid, 4,4'-diaminodiphenylmethane-3,3'-dicarboxylic acid, 1,2-bis(4-aminophenyl)ethane-3,3'-dicarboxylic acid, and 4,4'-diaminodiphenylether-3,3'-dicarboxylic acid; 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indan-5-amine, and 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-6-amine; diamines having a group "-N(D)-" such as the above formulae (5-7) to (5-7) (D represents a protecting group which is eliminated by heating and replaced with a hydrogen atom, preferably a carbamate-based protecting group, more preferably a tert-butoxycarbonyl group); diamines having a steroid skeleton such as cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestanyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, and 3,6-bis(4-aminobenzoyloxy)cholestane; diamines represented by the following formulae (V-1) to (V-2); 2,7-diaminofluorene, or 9,9-bis(4-aminobenzoyloxy)cholestane. aromatic diamines typified by diamines having a fluorene skeleton, such as bis(4-aminophenyl)fluorene; diamines having a siloxane bond, such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane; acyclic aliphatic diamines typified by metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, and the like; alicyclic diamines typified by 1,3-bis(aminomethyl)cyclohexane, 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), and diamines in which two amino groups are bonded to a group represented by any one of formulas (Y-1) to (Y-167) described in WO2018/117239, and the like.

(Ar ₁ and Ar _1' each represent a benzene ring, a biphenyl structure, or a naphthalene ring, and one or more hydrogen atoms on the benzene ring, the biphenyl structure, or the naphthalene ring may be substituted with a monovalent group. L ₁ and L _1' each represent a single bond, -O-, -C(=O)-, or -O-C(=O)-. A represents -CH ₂ -, an alkylene group having 2 to 12 carbon atoms, or a divalent organic group in which at least one of -O-, -C(=O)-O-, and -O-C(=O)- is inserted between the carbon-carbon bonds of the alkylene group. Any hydrogen atom possessed by A may be substituted with a halogen atom.

One or more hydrogen atoms on the benzene ring, biphenyl structure, or naphthalene ring may be substituted with a monovalent group, and examples of the monovalent group include a halogen atom, an alkyl group having 1 to 3 carbon atoms, an alkenyl group having 2 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, a fluoroalkyl group having 1 to 3 carbon atoms, a fluoroalkenyl group having 2 to 3 carbon atoms, a fluoroalkoxy group having 1 to 3 carbon atoms, an alkyloxycarbonyl group having 2 to 3 carbon atoms, a cyano group, and a nitro group.)

(In formula (d _AL -2), the sum of l, m and n is 1 to 12. In formula (d _AL -6), the sum of m1, m2 and n is 1 to 12. In formula (d _AL -8), the sum of m1, m2 and n is 3 to 12. In formula (d _AL -11), the sum of l, m and n is 3 to 12.)

In the above formula (V-1), m and n are integers of 0 to 3, and satisfy 1≦m+n≦4. j is an integer of 0 or 1. X ¹ represents -(CH ₂ ) _a - (a is an integer of 1 to 15), -CONH-, -NHCO-, -CO-N(CH ₃ )-, -NH-, -O-, -CH ₂ O-, -CH ₂ -OCO-, -COO-, or -OCO-. R ¹ represents a monovalent group such as a fluorine atom, a fluorine atom-containing alkyl group having 1 to 10 carbon atoms, a fluorine atom-containing alkoxy group having 1 to 10 carbon atoms, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an alkoxyalkyl group having 2 to 10 carbon atoms. In the above formula (V-2), X ² represents —O—, —CH ₂ O—, —CH ₂ —OCO—, —COO—, or —OCO—, and when there are two of m, n, X ¹ and R ¹ , each independently has the above definition.

Examples of the nitrogen atom-containing heterocycle that may be contained in the diamine having the specific nitrogen atom-containing structure include pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, pyridazine, pyrazine, indole, benzimidazole, purine, quinoline, isoquinoline, naphthyridine, quinoxaline, phthalazine, triazine, carbazole, acridine, piperidine, piperazine, pyrrolidine, and hexamethyleneimine. Among these, pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole, and acridine are preferred.
From the viewpoint of obtaining the effects of the present invention, the diamine is preferably a diamine represented by the formula (d _AL ). The content of the diamine represented by the formula (d _AL ) is preferably 5 mol% or more, preferably 10 mol% or more, based on 1 mol of the diamine component used in the production of the polymer (P). The content of the diamine represented by the formula (d _AL ) may be 90 mol% or less, or 80 mol% or less, based on 1 mol of the diamine component used in the production of the polymer (P).

The diamine component used in the production of the polymer (P) may contain, in addition to the diamine represented by the formula (d _AL ), another diamine selected from the group consisting of the phenylenediamine, the diaminobiphenyl compound, the diamine having a diphenyl ether structure, the diamine having a tetracarboxylic diimide structure, the diamine having an amide bond, the diamine having a urea bond, and the diamine having a group "-N(D)-".
The content of the other diamine is more preferably 10 to 95 mol%, even more preferably 10 to 90 mol%, and even more preferably 20 to 90 mol%, relative to 1 mol of the diamine component used in the production of the polymer (P). When two or more kinds of other diamines are contained, the content of each diamine constituting each of the other diamines may be 30 mol% or less.
(Liquid crystal alignment agent)
The liquid crystal aligning agent of the present invention is a liquid composition obtained by dispersing or dissolving the polymer (P) and other components used as necessary, preferably in a suitable solvent.

The liquid crystal alignment agent of the present invention may contain other polymers in addition to the polymer (P). Specific examples of other polymers include, in addition to the polymer (P), at least one polymer (also referred to as polymer (B) in the present invention) selected from the group consisting of polyimide precursors obtained using a tetracarboxylic acid component that does not contain the specific alicyclic tetracarboxylic acid derivative (p1), polyimide precursors obtained using a tetracarboxylic acid component that does not contain the specific alicyclic tetracarboxylic acid derivative (p2), and polyimides that are imidized products of these polyimide precursors; polysiloxanes, polyesters, polyamides, polyureas, polyorganosiloxanes, cellulose derivatives, polyacetals, polystyrene derivatives, poly(styrene-maleic anhydride) copolymers, poly(isobutylene-maleic anhydride) copolymers, poly(vinyl ether-maleic anhydride) copolymers, poly(styrene-phenylmaleimide) derivatives, and polymers selected from the group consisting of poly(meth)acrylates.

Specific examples of poly(styrene-maleic anhydride) copolymers include SMA1000, SMA2000, SMA3000 (manufactured by Cray Valley) and GSM301 (manufactured by Gifu Ceramics Manufacturing Co., Ltd.), and a specific example of poly(isobutylene-maleic anhydride) copolymers includes Isoban-600 (manufactured by Kuraray Co., Ltd.). A specific example of poly(vinyl ether-maleic anhydride) copolymers includes Gantrez AN-139 (methyl vinyl ether maleic anhydride resin, manufactured by Ashland Co., Ltd.). Among these, polymer (B) is more preferred in terms of reducing residual DC-induced afterimages.

The other polymers may be used alone or in combination of two or more. The content of the other polymers is preferably 90 parts by mass or less, more preferably 10 to 90 parts by mass, and even more preferably 20 to 80 parts by mass, based on 100 parts by mass of the total of the polymers contained in the liquid crystal alignment agent.
(Polymer (B))
Specific examples of the tetracarboxylic acid component used in the production of the polymer (B) include acyclic aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, aromatic tetracarboxylic acid dianhydrides, and derivatives thereof.
Here, the acyclic aliphatic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups bonded to a chain hydrocarbon structure, but does not necessarily have to be composed of a chain hydrocarbon structure alone, and may have an alicyclic structure or an aromatic ring structure as a part thereof.

Alicyclic tetracarboxylic dianhydrides are acid dianhydrides obtained by intramolecular dehydration of four carboxy groups, including at least one carboxy group bonded to an alicyclic structure. However, none of these four carboxy groups are bonded to an aromatic ring. In addition, they do not necessarily have to be composed of an alicyclic structure alone, and may have a chain hydrocarbon structure or an aromatic ring structure as part of them.
The aromatic tetracarboxylic acid dianhydride is not particularly limited as long as it is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups, including at least one carboxy group bonded to an aromatic ring.
From the viewpoint of enhancing liquid crystal alignment, the alicyclic tetracarboxylic acid dianhydride or a derivative thereof is preferably a tetracarboxylic acid dianhydride having at least one partial structure selected from the group consisting of a cyclobutane ring structure, a cyclopentane ring structure, and a cyclohexane ring structure, or a derivative thereof.
The aromatic tetracarboxylic dianhydride or a derivative thereof is preferably a tetracarboxylic dianhydride having a benzene ring structure or a derivative thereof from the viewpoint of enhancing the liquid crystal alignment property.
Specific examples of tetracarboxylic dianhydrides or derivatives thereof that can be used as the tetracarboxylic acid component of the polymer (B) include the following tetracarboxylic dianhydrides or derivatives thereof.
acyclic aliphatic tetracarboxylic dianhydride such as 1,2,3,4-butane tetracarboxylic dianhydride or (Q) ₂ -A (Q represents a monovalent succinic anhydride structure, and A represents a divalent organic group in which a part of the -CH ₂ _- of the alkylene group is replaced by at least one of a phenylene group, -O-, -NR- (R represents a hydrogen atom or a methyl group), -C(═O)-NR- (R represents a hydrogen atom or a methyl group), -C(═O)-O-, and -O-C(═O)-); 1,2,3,4-cyclobutane tetracarboxylic dianhydride, 1,2,3,4-cyclopentane tetracarboxylic dianhydride, 1,2,4,5-cyclohexane tetracarboxylic dianhydride, and 3,3',4,4'-dicyclohexyl tetracarboxylic dianhydride; , 2,3,5-tricarboxycyclopentylacetic dianhydride, 4-(2,5-dioxotetrahydrofuran-3-yl)tetrahydronaphthalene-1,2-dicarboxylic anhydride, 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, or alicyclic tetracarboxylic dianhydrides such as the tetracarboxylic dianhydrides represented by the above formulas (T2-1) to (T2-3); pyromellitic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-biphenyl tetracarboxylic dianhydride, 2,2',3,3'-biphenyl tetracarboxylic dianhydride, Aromatic tetracarboxylic dianhydrides such as phenyltetracarboxylic dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)-2,2-diphenylpropane dianhydride, ethylene glycol bisanhydrotrimellitate, 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 4,4'-carbonyldiphthalic anhydride, 4,4'-(1,4-phenylenedioxy)bis(phthalic anhydride), or 4,4'-(1,4-phenylenedimethylene)bis(phthalic anhydride); and tetracarboxylic dianhydrides as described in JP-A-2010-97188.
The tetracarboxylic acid component used in the production of the polymer (B) more preferably contains a tetracarboxylic acid dianhydride having at least one partial structure selected from the group consisting of a benzene ring, a cyclobutane ring, a cyclopentane ring, and a cyclohexane ring, or a derivative thereof.

Examples of the diamine component for obtaining the polymer (B) include the diamines exemplified for the polymer (P) above. Among them, the first diamine, a diamine having a urea bond, a diamine having an amide bond, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-bis(3-amino-4-methylphenyl)hexafluoropropane, 2,2-bis(4-aminophenyl) ... Preferably, the diamine component contains at least one diamine selected from the group consisting of 2,2-bis(3-amino-4-methylphenyl)propane, 4,4'-diaminobenzophenone, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-aminobenzyl)benzene, the diamines having the specific nitrogen atom-containing structure, the diamines having a carboxy group, 4-(2-(methylamino)ethyl)aniline, and 4-(2-aminoethyl)aniline. As the diamine component, one type of diamine may be used alone, or two or more types may be used in combination.
(Production of polyamic acid)
The polyamic acid is produced by reacting a diamine component with a tetracarboxylic acid component in an organic solvent. The ratio of the tetracarboxylic acid component and the diamine component used in the reaction for producing the polyamic acid is preferably such that the acid anhydride group of the tetracarboxylic acid component is 0.5 to 2 equivalents, more preferably 0.8 to 1.2 equivalents, per equivalent of the amino group of the diamine component. As in the case of a normal polycondensation reaction, the closer the equivalent of the acid anhydride group of the tetracarboxylic acid component is to 1 equivalent, the higher the molecular weight of the polyamic acid produced.

The reaction temperature in the production of polyamic acid is preferably −20 to 150° C., more preferably 0 to 100° C. The reaction time is preferably 0.1 to 24 hours, more preferably 0.5 to 12 hours. The production of polyamic acid can be carried out at any concentration, but the concentration of polyamic acid is preferably 1 to 50% by mass, more preferably 5 to 30% by mass. The reaction can be carried out at a high concentration in the early stage of the reaction, and then a solvent can be added.
Specific examples of the organic solvent include cyclohexanone, cyclopentanone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, and 1,3-dimethyl-2-imidazolidinone. In addition, when the polymer has high solubility in the solvent, a solvent such as methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, propylene glycol monomethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, diethylene glycol monomethyl ether, or diethylene glycol monoethyl ether can be used.
(Production of polyamic acid ester)
The polyamic acid ester can be obtained by a known method such as, for example, [I] a method of reacting the polyamic acid obtained by the above-mentioned method with an esterifying agent, [II] a method of reacting a tetracarboxylic acid diester with a diamine, or [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine.
(Production of Polyimide)
Polyimide can be obtained by ring-closing (imidizing) a polyimide precursor such as the polyamic acid or polyamic acid ester. The imidization ratio in this specification refers to the ratio of imide groups to the total amount of imide groups derived from tetracarboxylic dianhydride or its derivatives and carboxyl groups (or their derivatives). The imidization ratio does not necessarily need to be 100% and can be adjusted according to the application and purpose.

Methods for imidizing a polyimide precursor include thermal imidization, in which a solution of the polyimide precursor is heated as is, and catalytic imidization, in which a catalyst is added to a solution of the polyimide precursor.

When thermally imidizing the polyimide precursor in a solution, the temperature is preferably 100 to 400°C, more preferably 120 to 250°C, and it is preferable to carry out the process while removing the water produced by the imidization reaction from the system.

Catalytic imidization of polyimide precursors can be carried out by adding a basic catalyst and an acid anhydride to a solution of the polyimide precursor and stirring the solution at preferably -20 to 250°C, more preferably 0 to 180°C. The amount of the basic catalyst is preferably 0.5 to 30 molar times, more preferably 2 to 20 molar times, the amount of the acid anhydride is preferably 1 to 50 molar times, more preferably 3 to 30 molar times, the amount of the amic acid group. Examples of basic catalysts include pyridine, triethylamine, trimethylamine, tributylamine, and trioctylamine, and among these, pyridine is preferred because it has a suitable basicity for promoting the reaction. Examples of acid anhydrides include acetic anhydride, trimellitic anhydride, and pyromellitic anhydride, and among these, acetic anhydride is preferred because it makes purification after the reaction easy. The imidization rate by catalytic imidization can be controlled by adjusting the amount of catalyst, reaction temperature, and reaction time.

When recovering the polyimide precursor or polyimide produced from a reaction solution of a polyimide precursor or polyimide, the reaction solution may be poured into a solvent to cause precipitation. Examples of solvents used for precipitation include methanol, ethanol, isopropyl alcohol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, and water. The polymer precipitated by pouring into the solvent can be recovered by filtration, and then dried at room temperature or by heating under normal or reduced pressure. The recovered polymer can be redissolved in an organic solvent and the reprecipitation recovery operation repeated 2 to 10 times to reduce the amount of impurities in the polymer. Examples of the solvent used in this case include alcohols, ketones, and hydrocarbons. Using three or more solvents selected from these is preferable because it further increases the efficiency of purification.

When producing the polyimide precursor or polyimide of the present invention, a terminal-capping polymer may be produced using a suitable terminal-capping agent together with a tetracarboxylic acid component containing a tetracarboxylic dianhydride or a derivative thereof, and a diamine component containing a diamine. The terminal-capping polymer has the effect of improving the film hardness of the liquid crystal alignment film obtained by coating, and improving the adhesion properties between the sealant and the liquid crystal alignment film.

Examples of the terminals of the polyimide precursor or polyimide in the present invention include amino groups, carboxy groups, acid anhydride groups, and groups derived from terminal blocking agents described below. The amino groups, carboxy groups, and acid anhydride groups can be obtained by a normal condensation reaction, or by blocking the terminals with the terminal blocking agents described below.

Examples of end-capping agents include acid anhydrides such as acetic anhydride, maleic anhydride, nadic anhydride, phthalic anhydride, itaconic anhydride, 1,2-cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, 3-(3-trimethoxysilyl)propyl)-3,4-dihydrofuran-2,5-dione, 4,5,6,7-tetrafluoroisobenzofuran-1,3-dione, and 4-ethynylphthalic anhydride; dicarbonate diester compounds such as di-tert-butyl dicarbonate and diallyl dicarbonate; chlorocarbonyl compounds such as acryloyl chloride, methacryloyl chloride, and nicotinic acid chloride; Examples of the monoamine compounds include aniline, 2-aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, and n-octylamine; and isocyanates having unsaturated bonds such as ethyl isocyanate, phenyl isocyanate, naphthyl isocyanate, or 2-acryloyloxyethyl isocyanate and 2-methacryloyloxyethyl isocyanate.

The proportion of the end-capping agent used is preferably 0.01 to 20 molar parts, and more preferably 0.01 to 10 molar parts, per 100 molar parts of the total diamine components used.

The polystyrene-equivalent weight average molecular weight (Mw) of the polyimide precursor and polyimide measured by gel permeation chromatography (GPC) is preferably 1,000 to 500,000, and more preferably 2,000 to 300,000. The molecular weight distribution (Mw/Mn), which is expressed as the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC, is preferably 15 or less, and more preferably 10 or less. Having the molecular weight within this range ensures good liquid crystal alignment in the liquid crystal display element.

The organic solvent contained in the liquid crystal alignment agent according to the present invention is not particularly limited as long as it can uniformly dissolve the polymer (P) and other polymers added as necessary. For example, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N,N-dimethylpropionamide, tetramethylurea, N,N-diethylformamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylsulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropaneamide, dimethylsulfon ... Examples of suitable solvents include N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(tert-butyl)-2-pyrrolidone, N-(n-pentyl)-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone (collectively referred to as good solvents). Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, and γ-butyrolactone are preferred. The content of the good solvent is preferably 20 to 99% by mass, more preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass, of the total solvent contained in the liquid crystal alignment agent.

The organic solvent contained in the liquid crystal alignment agent is preferably a mixed solvent that uses, in addition to the above-mentioned solvent, a solvent (also called a poor solvent) that improves the applicability when applying the liquid crystal alignment agent and the surface smoothness of the coating film. Specific examples of poor solvents are listed below, but are not limited to these. The content of the poor solvent is preferably 1 to 80 mass % of the total solvent contained in the liquid crystal alignment agent, more preferably 10 to 80 mass %, and particularly preferably 20 to 70 mass %. The type and content of the poor solvent are appropriately selected depending on the application device, application conditions, application environment, etc. of the liquid crystal alignment agent.

Examples of poor solvents include diisopropyl ether, diisobutyl ether, diisobutyl carbinol (2,6-dimethyl-4-heptanol), ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,2-dibutoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, 4-hydroxy-4-methyl-2-pentanone, diethylene glycol methyl ethyl ether, diethylene glycol dibutyl ether, 3-ethoxybutyl acetate, 1-methylpentyl acetate, 2-ethylbutyl acetate, 2-ethylhexyl acetate, ethylene glycol monoacetate, ethylene glycol diacetate, propylene carbonate, ethylene carbonate, ethylene glycol monobutyl ether, ethylene glycol monoisoamyl ether, ethylene glycol monohexyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, 1-(2-butoxyethoxy)-2-propanol. , 2-(2-butoxyethoxy)-1-propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monopropyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene Examples include glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, cyclohexyl acetate, 4-methyl-2-pentyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, and diisobutyl ketone (2,6-dimethyl-4-heptanone).

Among these, diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, and diisobutyl ketone are preferred.

Preferred combinations of good and poor solvents include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and propylene glycol diacetate, N,N-dimethyl lactamide and diisobutyl ketone, and N-methyl-2-pyrrolidone. and ethyl 3-ethoxypropionate, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether acetate ether, N-ethyl-2-pyrrolidone and dipropylene glycol dimethyl ether, N,N-dimethyl lactamide and ethylene glycol monobutyl ether, N,N-dimethyl lactamide and propylene glycol diacetate, N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone and diethylene glycol monoethyl ether and butyl cellosolve acetate, N-methyl-2-pyrrolidone and diethylene glycol monomethyl ether and butyl cellosolve acetate, N,N-dimethyl lactamide and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone and γ-butyro Lactone and 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone and N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol monomethyl ether N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol diacetate, N-ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol dimethyl ether, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and diisobutyl ketone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol diacetate, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisobutyl ketone, N-methyl- 2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisobutyl carbinol, N-methyl-2-pyrrolidone, γ-butyrolactone, and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, diethylene glycol diethyl ether, ethyl ether and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether and propylene glycol diacetate, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether and diisobutyl ketone, N-ethyl-2-pyrrolidone, γ-butyrolactone and diisobutyl ketone, N-ethyl-2-pyrrolidone, N,N-dimethyl lactamide and diisobutyl ketone, N-methyl-2-pyrrolidone, ethylene glycol monobutyl ether and ethylene glycol monobutyl ether acetate, γ-butyrolactone and ethylene glycol monobutyl ether acetate and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, ethylene glycol monobutyl ether acetate, and propylene glycol dimethyl ether, N-methyl-2-pyrrolidone, 4-methyl-2-pentyl acetate, and ethylene glycol monobutyl ether, N-ethyl-2-pyrrolidone, cyclohexyl acetate, and 4-hydroxy-4-methyl-2-pentanone, cyclohexanone, propylene glycol monomethyl ether, cyclopentanone, and propylene glycol monomethyl ether, and N-methyl-2-pyrrolidone, cyclohexanone, and propylene glycol monomethyl ether.
(Liquid crystal alignment agent)
The liquid crystal aligning agent of the present invention contains the above-mentioned polymer (P), and, if necessary, the above-mentioned other polymers, and the above-mentioned organic solvent.
The total content of the polymers contained in the liquid crystal aligning agent of the present invention can be appropriately changed depending on the thickness of the coating film to be formed, but it is preferably 1% by mass or more from the viewpoint of forming a uniform and defect-free coating film, and is preferably 10% by mass or less from the viewpoint of storage stability of the solution. The particularly preferred total content of the polymers is 2 to 8% by mass.

The content of the polymer (P) used in the present invention is preferably 1 to 100 mass %, more preferably 10 to 100 mass %, particularly preferably 20 to 100 mass %, based on the total amount of the polymer contained in the liquid crystal alignment agent.
The liquid crystal alignment agent of the present invention may contain other components (hereinafter also referred to as additive components) in addition to the above polymer (P), the other polymers, and the organic solvent. Examples of such additive components include at least one crosslinking compound selected from the group consisting of a crosslinking compound having at least one substituent selected from an oxiranyl group, an oxetanyl group, a blocked isocyanate group, an oxazoline group, a cyclocarbonate group, a hydroxyalkyl group, and an alkoxy group, and a crosslinking compound having a polymerizable unsaturated group, a functional silane compound, a metal chelate compound, a curing accelerator, a surfactant, an antioxidant, a sensitizer, a preservative, and a compound for adjusting the dielectric constant or electrical resistance of the resulting liquid crystal alignment film. Specific preferred examples of the crosslinkable compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, bisphenol A type epoxy resins such as Epicoat 828 (manufactured by Mitsubishi Chemical Corporation), bisphenol F type epoxy resins such as Epicoat 807 (manufactured by Mitsubishi Chemical Corporation), hydrogenated bisphenol A type epoxy resins such as YX-8000 (manufactured by Mitsubishi Chemical Corporation), and epoxy resins having a biphenyl skeleton such as YX6954BH30 (manufactured by Mitsubishi Chemical Corporation). epoxy resins containing glyceryl ether, phenol novolac type epoxy resins such as EPPN-201 (manufactured by Nippon Kayaku Co., Ltd.), (o, m, p-)cresol novolac type epoxy resins such as EOCN-102S (manufactured by Nippon Kayaku Co., Ltd.), triglycidyl isocyanurates such as TEPIC (manufactured by Nissan Chemical Industries, Ltd.), alicyclic epoxy resins such as Celloxide 2021P (manufactured by Daicel Corporation), N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N compounds having two or more oxiranyl groups, such as compounds containing a tertiary nitrogen atom, such as N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, and tetrakis(glycidyloxymethyl)methane; compounds having two or more oxetanyl groups, such as those described in paragraphs [0170] to [0175] of WO2011/132751; Compounds having a blocked isocyanate group, such as Table M, Coronate 2503, 2515, 2507, 2513, 2555, Millionate MS-50 (all manufactured by Tosoh Corporation), Takenate B-830, B-815N, B-820NSU, B-842N, B-846N, B-870N, B-874N, B-882N (all manufactured by Mitsui Chemicals, Inc.); 2,2'-bis(2-oxazoline), 2,2'-bis(4-methyl-2-oxazoline), 2 ,2'-bis(5-methyl-2-oxazoline), 1,2,4-tris(2-oxazolinyl)-benzene, and compounds having an oxazoline group such as EPOCROS (manufactured by Nippon Shokubai Co., Ltd.); compounds having a cyclocarbonate group described in paragraphs [0025] to [0030] and [0032] of WO2011/155577; N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide, 2,2-bis(4-hydroxy-3,5- hydroxyl or alkoxyl group-containing compounds such as 2,2-bis(4-hydroxy-3,5-dimethoxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dihydroxymethylphenyl)-1,1,1,3,3,3-hexafluoropropane; and compounds represented by glycerin mono(meth)acrylate, glycerin di(meth)acrylate (1,2-,1,3-mixture), glycerin tris(meth)acrylate, glycerin 1,3-diglycerolate di(meth)acrylate, pentaerythritol tri(meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, pentaethylene glycol mono(meth)acrylate, and hexaethylene glycol mono(meth)acrylate.

The content of the crosslinking compound is preferably 0.1 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the liquid crystal alignment agent.

The compound for adjusting the dielectric constant and electrical resistance is, for example, a monoamine having a nitrogen atom-containing aromatic heterocycle, such as 3-picolylamine. The content of the monoamine having a nitrogen atom-containing aromatic heterocycle is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, per 100 parts by mass of the polymer component contained in the liquid crystal alignment agent.

Preferred specific examples of the functional silane compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycidoxypropylmethyldimethoxysilane. Examples of the functional silane include 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyl diethoxysilane, 3-glycidoxypropyl triethoxysilane, p-styryl trimethoxysilane, 3-methacryloxypropyl methyl dimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyl diethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, tris[3-(trimethoxysilyl)propyl]isocyanurate, 3-mercaptopropyl methyl dimethoxysilane, 3-mercaptopropyl trimethoxysilane, and 3-isocyanate propyl triethoxysilane. The content of the functional silane compound is preferably 0.1 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, based on 100 parts by mass of the polymer component contained in the liquid crystal alignment agent.

The solids concentration in the liquid crystal alignment agent (the ratio of the total mass of the components other than the solvent in the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) is appropriately selected taking into consideration the viscosity, volatility, etc., but is preferably 1 to 10 mass%.

The particularly preferred range of solid content varies depending on the method used to apply the liquid crystal alignment agent to the substrate. For example, when using a spin coating method, it is particularly preferred that the solid content is 1.5 to 4.5% by mass. When using a printing method, it is particularly preferred that the solid content is 3 to 9% by mass, thereby making the solution viscosity 12 to 50 mPa·s. When using an inkjet method, it is particularly preferred that the solid content is 1 to 5% by mass, thereby making the solution viscosity 3 to 15 mPa·s. The temperature when preparing the liquid crystal alignment agent is preferably 10 to 50°C, more preferably 20 to 30°C.
<Liquid crystal alignment film/Liquid crystal display element>
A liquid crystal alignment film can be produced by using the liquid crystal alignment agent. The liquid crystal display element of the present invention is provided with the liquid crystal alignment film. The operation mode of the liquid crystal display element according to the present invention is not particularly limited, and it can be applied to various operation modes such as the TN mode, STN (Super Twisted Nematic) mode, vertical alignment mode (including VA-MVA mode, VA-PVA mode, etc.), IPS mode, FFS mode, optical compensation bend mode (OCB mode), etc. The liquid crystal alignment film of the present invention is a liquid crystal alignment film suitable for liquid crystal display elements of a horizontal alignment mode such as the IPS mode or FFS mode.
The liquid crystal display element of the present invention can be produced, for example, by a method including the following steps (1) to (3), a method including steps (1) to (4), a method including steps (1) to (3), (3b), and (4), a method including steps (1) to (2) and (4), a method including steps (1) to (3), (4), and (5), or a method including steps (1) to (3), (4), and (6).
<Step (1): Step of applying a liquid crystal alignment agent to at least one of the first substrate and the second substrate>
Step (1) is a step of applying the liquid crystal aligning agent of the present invention onto a substrate. Specific examples of step (1) are as follows.

The liquid crystal alignment agent of the present invention is applied to one side of a substrate on which a patterned transparent conductive film is provided by an appropriate application method such as a roll coater method, a spin coat method, a printing method, or an inkjet method. The substrate is not particularly limited as long as it is a highly transparent substrate, and plastic substrates such as acrylic substrates and polycarbonate substrates can be used in addition to glass substrates and silicon nitride substrates. In addition, in a reflective liquid crystal display element, an opaque material such as a silicon wafer can be used for only one substrate, and in this case, a material that reflects light such as aluminum can be used for the electrode. Furthermore, when manufacturing an IPS or FFS liquid crystal display element, a substrate on which an electrode made of a transparent conductive film or a metal film patterned into a comb shape is provided and an opposing substrate on which no electrode is provided are used. The transparent conductive film can be formed by a known method using, for example, indium tin oxide (ITO), indium zinc oxide (IZO), or a mixture thereof.

Examples of the method for applying the liquid crystal alignment agent to a substrate and forming a film include screen printing, offset printing, flexographic printing, an inkjet method, a spray method, etc. Among these, the application and film formation method by the inkjet method is preferably used.
<Step (2): Step of baking the applied liquid crystal alignment agent>
In the step (2), the liquid crystal alignment agent applied on the substrate is baked to form a film. Specific examples of the step (2) are as follows.

After the liquid crystal alignment agent is applied to the substrate in step (1), the solvent can be evaporated or the polyamic acid or polyamic acid ester can be thermally imidized by a heating means such as a hot plate, a heat circulation type oven, or an IR (infrared) type oven. The drying and baking steps after the application of the liquid crystal alignment agent of the present invention can be performed at any temperature and time, and may be performed multiple times. The temperature at which the solvent of the liquid crystal alignment agent is reduced can be, for example, 40 to 180°C. From the viewpoint of shortening the process, the baking can be performed at 40 to 150°C. The baking time is not particularly limited, but can be 1 to 10 minutes or 1 to 5 minutes. When thermally imidizing the polyamic acid or polyamic acid ester, a baking step can be added after the above step, for example, at a temperature range of 150 to 300°C or 150 to 250°C. The baking time is not particularly limited, but can be 5 to 40 minutes or 5 to 30 minutes.

If the film thickness after firing is too thin, the reliability of the liquid crystal display element may decrease, so it is preferable for the film thickness to be 5 to 300 nm, and more preferably 10 to 200 nm.

<Step (3): Step of subjecting the film obtained in step (2) to an alignment treatment>
Step (3) is a step of, in some cases, performing an alignment treatment on the film obtained in step (2). That is, in a horizontal alignment type liquid crystal display element such as an IPS type or FFS type, an alignment ability imparting treatment is performed on the coating film. On the other hand, in a vertical alignment type liquid crystal display element such as a VA type or PSA type, the formed coating film can be used as it is as a liquid crystal alignment film, but the coating film may also be subjected to an alignment ability imparting treatment. Examples of the alignment treatment method for the liquid crystal alignment film include a rubbing treatment method and a photo-alignment treatment method, and more preferably, a photo-alignment treatment method.
The photo-alignment treatment method includes a method in which the surface of the film-like material is irradiated with radiation (more preferably with polarized radiation) to impart liquid crystal alignment properties (also referred to as liquid crystal alignment ability).
The radiation may be ultraviolet light or visible light having a wavelength of 100 to 800 nm, preferably ultraviolet light having a wavelength of 100 to 400 nm, more preferably ultraviolet light having a wavelength of 200 to 400 nm.
The liquid crystal alignment film of the present invention is more preferably a liquid crystal alignment film obtained by irradiating with polarized ultraviolet light.
The rubbing treatment may be carried out by rubbing the coating film in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton.

In the above photo-alignment treatment method, when the radiation is polarized, it may be linearly polarized or partially polarized. Furthermore, when 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. When irradiating with unpolarized radiation, it is preferable that the irradiation direction is oblique.

The radiation dose is more preferably 1 to 10,000 mJ/cm ² , further preferably 100 to 1000 mJ/cm ² , and most preferably 100 to 500 mJ/cm ² .

When radiation is applied in the photo-alignment treatment, in order to improve the liquid crystal alignment, the substrate having the film-like material may be irradiated while being heated at, for example, 50 to 250° C. The liquid crystal alignment film thus produced can stably align liquid crystal molecules in a certain direction.
<Step (3b): Step of performing heat treatment>
The coating film irradiated with the above-mentioned radiation may be subjected to a heat treatment. The temperature for such heat treatment is preferably 50 to 300° C., more preferably 120 to 250° C. The time for the heat treatment is preferably 1 to 30 minutes.
<Step (4): A step of disposing a liquid crystal layer between a first substrate and a second substrate so as to be adjacent to the alignment-treated film to prepare a liquid crystal cell>
Step (4) is a step of preparing a liquid crystal cell by disposing a liquid crystal layer between the first substrate and the second substrate so as to be adjacent to the alignment-treated film. In the following, a case where a liquid crystal alignment film is formed on each of the first substrate and the second substrate is exemplified. Specifically, the following two methods are given.

In the first method, first, two substrates are placed facing each other with a gap (cell gap) between them so that their liquid crystal alignment films face each other. Next, the periphery of the two substrates is attached using a sealant, and the liquid crystal composition is injected and filled into the substrate surfaces and the cell gap defined by the sealant so that it comes into contact with the film surface, and then the injection hole is sealed.

The second method is called the ODF (One Drop Fill) method. For example, a UV-curable resin composition (hereinafter also referred to as a sealant) is applied to a predetermined location on one of the two substrates on which a liquid crystal alignment film has been formed, and the liquid crystal composition is then dropped onto several predetermined locations on the liquid crystal alignment film surface. The other substrate is then attached so that the liquid crystal alignment film faces the other substrate, and the liquid crystal composition is spread over the entire surface of the substrate and brought into contact with the film surface. Next, the entire surface of the substrate is irradiated with UV light to cure the sealant. In either method, it is desirable to further heat the substrate to a temperature at which the liquid crystal composition used assumes an isotropic phase, and then slowly cool it to room temperature to remove the flow alignment that occurs during liquid crystal filling.

When a rubbing treatment is performed on the coating film, the two substrates are placed facing each other so that the rubbing directions of the coating films are at a predetermined angle to each other, for example, perpendicular or anti-parallel.

As the sealing agent, for example, an epoxy resin containing a hardener and aluminum oxide spheres as spacers can be used.
The liquid crystal composition is not particularly limited, and may be any of various liquid crystal compositions containing at least one liquid crystal compound (liquid crystal molecule) and having positive or negative dielectric anisotropy. In the following description, a liquid crystal composition having a positive dielectric anisotropy is also called a positive liquid crystal, and a liquid crystal composition having a negative dielectric anisotropy is also called a negative liquid crystal.

The liquid crystal composition may contain a liquid crystal compound having a fluorine atom, a hydroxy group, an amino group, a fluorine atom-containing group (e.g., a trifluoromethyl group), a cyano group, an alkyl group, an alkoxy group, an alkenyl group, an isothiocyanate group, a heterocycle, a cycloalkane, a cycloalkene, a steroid skeleton, a benzene ring, or a naphthalene ring, and may contain a compound having two or more rigid portions (mesogenic skeletons) that exhibit liquid crystallinity within the molecule (e.g., a bimesogenic compound in which two rigid biphenyl structures or terphenyl structures are linked by an alkylene group).

The liquid crystal composition may be a liquid crystal composition exhibiting a nematic phase, a liquid crystal composition exhibiting a smectic phase, or a liquid crystal composition exhibiting a cholesteric phase.

The liquid crystal composition may further contain additives from the viewpoint of improving the liquid crystal alignment. Such additives include photopolymerizable monomers such as compounds having a polymerizable group; optically active compounds (e.g., S-811 manufactured by Merck Ltd.); antioxidants; UV absorbers; dyes; antifoaming agents; polymerization initiators; and polymerization inhibitors.

Positive liquid crystals include ZLI-2293, ZLI-4792, MLC-2003, MLC-2041, MLC-3019, and MLC-7081 manufactured by Merck; and PA-1492 manufactured by DIC.

Examples of negative type liquid crystals include MLC-6608, MLC-6609, MLC-6610, and MLC-7026-100 manufactured by Merck.

Another example of a liquid crystal containing a compound with a polymerizable group is MLC-3023 manufactured by Merck.

The liquid crystal alignment agent of the present invention is also preferably used in a liquid crystal display element (PSA type liquid crystal display element) manufactured through a process (hereinafter, this process is also referred to as process (5)) in which a liquid crystal composition containing a polymerizable compound that is polymerized by at least one of active energy rays and heat is placed between the pair of substrates having a liquid crystal layer and a voltage is applied between the electrodes while the polymerizable compound is polymerized by at least one of irradiation with active energy rays and heating.

The liquid crystal alignment agent of the present invention is also preferably used in a liquid crystal display element (SC-PVA type liquid crystal display element) that has a liquid crystal layer between a pair of substrates equipped with electrodes, and is manufactured through a process of disposing a liquid crystal alignment film between the pair of substrates that contains a polymerizable group that is polymerized by at least one of active energy rays and heat, and applying a voltage between the electrodes (hereinafter, this process is also referred to as process (6)).

Then, if necessary, a polarizing plate can be attached to the outer surface of the liquid crystal cell to obtain a liquid crystal display element. Examples of polarizing plates that can be attached to the outer surface of the liquid crystal cell include a polarizing film called an "H film" made by stretching and aligning polyvinyl alcohol and absorbing iodine, sandwiched between cellulose acetate protective films, and a polarizing plate made of the H film itself.

The IPS substrate, which is a comb-tooth electrode substrate used in the IPS system, has a base material, a number of linear electrodes formed on the base material and arranged in a comb-tooth pattern, and a liquid crystal alignment film formed on the base material so as to cover the linear electrodes.

The FFS substrate, which is a comb-tooth electrode substrate used in the FFS method, has a base material, a surface electrode formed on the base material, an insulating film formed on the surface electrode, a plurality of linear electrodes formed on the insulating film and arranged in a comb-tooth shape, and a liquid crystal alignment film formed on the insulating film so as to cover the linear electrodes.

FIG. 1 is a schematic cross-sectional view showing an example of a horizontal electric field type liquid crystal display element of the present invention, which is an example of an IPS type liquid crystal display element.

In the in-plane switching type liquid crystal display element 1 illustrated in FIG. 1, liquid crystal 3 is sandwiched between a comb-tooth electrode substrate 2 having a liquid crystal alignment film 2c and a counter substrate 4 having a liquid crystal alignment film 4a. The comb-tooth electrode substrate 2 has a base material 2a, a plurality of linear electrodes 2b formed on the base material 2a and arranged in a comb-tooth shape, and a liquid crystal alignment film 2c formed on the base material 2a so as to cover the linear electrodes 2b. The counter substrate 4 has a base material 4b and a liquid crystal alignment film 4a formed on the base material 4b. The liquid crystal alignment film 2c is, for example, the liquid crystal alignment film of the present invention. The liquid crystal alignment film 4c is also a liquid crystal alignment film of the present invention.

In this in-plane switching type liquid crystal display element 1, when a voltage is applied to the linear electrodes 2b, an electric field is generated between the linear electrodes 2b as shown by the electric field lines L.

FIG. 2 is a schematic cross-sectional view showing another example of a horizontal electric field type liquid crystal display element of the present invention, which is an example of an FFS type liquid crystal display element.

In the in-plane switching type liquid crystal display element 1 illustrated in FIG. 2, liquid crystal 3 is sandwiched between a comb-tooth electrode substrate 2 having a liquid crystal alignment film 2h and a counter substrate 4 having a liquid crystal alignment film 4a. The comb-tooth electrode substrate 2 has a base material 2d, a surface electrode 2e formed on the base material 2d, an insulating film 2f formed on the surface electrode 2e, a plurality of linear electrodes 2g formed on the insulating film 2f and arranged in a comb-tooth shape, and a liquid crystal alignment film 2h formed on the insulating film 2f so as to cover the linear electrodes 2g. The counter substrate 4 has a base material 4b and a liquid crystal alignment film 4a formed on the base material 4b. The liquid crystal alignment film 2h is, for example, the liquid crystal alignment film of the present invention. The liquid crystal alignment film 4a is also the liquid crystal alignment film of the present invention.

In this IPS mode liquid crystal display element 1, when a voltage is applied to the plane electrodes 2e and the linear electrodes 2g, an electric field is generated between the plane electrodes 2e and the linear electrodes 2g as indicated by electric field lines L.
The liquid crystal alignment film of the present invention can be applied to various applications other than the above-mentioned applications. For example, it can be used as a liquid crystal alignment film for a retardation film, a liquid crystal alignment film for a scanning antenna or a liquid crystal array antenna, or a liquid crystal alignment film for a transmissive scattering type liquid crystal light control element.

The liquid crystal display element of the present invention can be effectively applied to various devices, such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, and information displays.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The abbreviations of the compounds used and the methods for measuring the respective physical properties are as follows.
(Organic solvent)
NMP: N-methyl-2-pyrrolidone BCS: Ethylene glycol monobutyl ether (tetracarboxylic dianhydride)
CA-1 to CA-6: Compounds represented by the following formulas (CA-1) to (CA-6), respectively.

Of the above tetracarboxylic dianhydrides, CA-1 corresponds to a specific alicyclic tetracarboxylic acid derivative (p1), and CA-2 to CA-4 correspond to a specific alicyclic tetracarboxylic acid derivative (p2).
(Diamine)
DA-1 to DA-4: Compounds represented by the following formulas (DA-1) to (DA-4), respectively.

<Measurement of Viscosity>
The measurement was performed at 25° C. using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL and a cone rotor TE-1 (1°34′, R24).
<Measurement of molecular weight>
Measurements were carried out using the following room temperature GPC (gel permeation chromatography) device, and Mn and Mw were calculated as values calculated in terms of polyethylene glycol and polyethylene oxide.

GPC apparatus: GPC-101 (Showa Denko K.K.); Column: GPC KD-803, GPC KD-805 (Showa Denko K.K.) in series; Column temperature: 50°C; Eluent: N,N-dimethylformamide (additives: lithium bromide monohydrate (LiBr.H ₂ O) 30 mmol/L, phosphoric acid anhydrous crystal (o-phosphoric acid) 30 mmol/L, tetrahydrofuran (THF) 10 mL/L); Flow rate: 1.0 mL/min. Standard sample for creating calibration curve: TSK standard polyethylene oxide (molecular weight: about 900,000, about 150,000, about 100,000, and about 30,000) (Tosoh Corporation) and polyethylene glycol (molecular weight: about 12,000, about 4,000, and about 1,000) (Polymer Laboratory Co., Ltd.).
<Measurement of imidization rate>
20 mg of polyimide powder was placed in an NMR sample tube (NMR sampling tube standard, φ5 (Kusano Scientific Co., Ltd.)), 1.0 mL of deuterated dimethyl sulfoxide ([D ₆ ]-DMSO, 0.05% tetramethylsilane (TMS) mixture) was added, and the mixture was sonicated to completely dissolve. This solution was measured for proton NMR at 500 MHz using a Fourier transform superconducting nuclear magnetic resonance (FT-NMR) "AVANCE III" (BRUKER Co., Ltd.).

(Chemical) The imidization rate was calculated by the following formula using a proton derived from a structure that does not change before and after imidization as the reference proton, and the peak integrated value of this proton and the proton peak integrated value derived from the NH group of the amic acid that appears around 9.5 to 10.0 ppm. In the formula below, x indicates the proton peak integrated value derived from the NH group of the amic acid, y indicates the peak integrated value of the reference proton, and α indicates the ratio of the number of reference protons to one proton of the NH group of the amic acid in the case of polyamic acid (imidization rate 0%).

Imidization rate (%)=(1−α·x/y)×100
[Polymer synthesis]
<Synthesis Example 1>
CA-1 (4.20 g, 18.7 mmol), CA-2 (1.09 g, 3.60 mmol), DA-1 (0.780 g, 7.21 mmol), DA-2 (1.76 g, 7.20 mmol), DA-3 (1.91 g, 4.80 mmol), DA-4 (1.54 g, 4.80 mmol) and NMP (82.7 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was stirred at 40 ° C. for 30 hours to obtain a solution of polyamic acid (PAA-1) having a solid content concentration of 12% by mass (viscosity: 380 mPa s). The Mn of this polyamic acid was 6,643 and the Mw was 14,885.
<Synthesis Example 2>
CA-1 (3.85 g, 17.2 mmol), CA-2 (1.42 g, 4.70 mmol), DA-1 (0.762 g, 7.05 mmol), DA-2 (1.72 g, 7.05 mmol), DA-3 (1.87 g, 4.70 mmol), DA-4 (1.51 g, 4.70 mmol) and NMP (81.6 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was stirred at 40 ° C. for 30 hours to obtain a solution of polyamic acid (PAA-2) having a solid content concentration of 12 mass% (viscosity: 300 mPa s). The Mn of this polyamic acid was 6,283 and the Mw was 13,669.
<Synthesis Example 3>
CA-1 (4.20 g, 18.7 mmol), CA-2 (1.09 g, 3.60 mmol), DA-1 (0.780 g, 7.21 mmol), DA-2 (1.76 g, 7.20 mmol), DA-3 (1.91 g, 4.80 mmol), DA-4 (1.54 g, 4.80 mmol) and NMP (82.7 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was stirred at 40 ° C. for 30 hours to obtain a solution of polyamic acid (PAA-3) having a solid content concentration of 12% by mass (viscosity: 380 mPa s). The Mn of this polyamic acid was 6,643 and the Mw was 14,885.

The above-obtained polyamic acid (PAA-3) solution (30.0 g) was weighed into a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, NMP was added so that the solids concentration was 9 mass%, acetic anhydride (2.27 g) and pyridine (0.590 g) were added, and the mixture was stirred at room temperature for 30 minutes, and then reacted at 55°C for 3 hours. This reaction solution was poured into methanol (300 g), and the resulting precipitate was filtered off. This precipitate was washed with methanol and dried under reduced pressure at 80°C to obtain polyimide powder. The imidization rate of this polyimide powder was 70%.

NMP was added to the obtained polyimide powder (2.70 g) so that the solid content concentration was 12 mass %, and the mixture was dissolved by stirring at 80° C. for 12 hours to obtain a polyimide solution (SPI-3) (viscosity: 400 mPa s). The Mn and Mw of this polyimide were 8,414 and 28,143, respectively.
<Synthesis Example 4>
CA-1 (4.02 g, 17.9 mmol), CA-3 (0.856 g, 3.45 mmol), DA-1 (0.746 g, 6.90 mmol), DA-2 (1.69 g, 6.90 mmol), DA-3 (1.83 g, 4.60 mmol), DA-4 (1.47 g, 4.60 mmol) and NMP (77.8 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was stirred at 40 ° C. for 30 hours to obtain a solution of polyamic acid (PAA-4) having a solids concentration of 12 mass% (viscosity: 110 mPa s). The Mn of this polyamic acid was 4,958 and the Mw was 10,531.
<Synthesis Example 5>
CA-1 (4.02 g, 17.9 mmol), CA-4 (0.863 g, 3.45 mmol), DA-1 (0.746 g, 6.90 mmol), DA-2 (1.69 g, 6.90 mmol), DA-3 (1.83 g, 4.60 mmol), DA-4 (1.47 g, 4.60 mmol) and NMP (77.9 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was stirred at 40 ° C. for 30 hours to obtain a solution of polyamic acid (PAA-5) having a solids concentration of 12% by mass (viscosity: 420 mPa s). The Mn of this polyamic acid was 6,263 and the Mw was 14,132.
<Synthesis Example 6>
CA-1 (10.2 g, 45.4 mmol), DA-1 (1.56 g, 14.4 mmol), DA-2 (3.52 g, 14.4 mmol), DA-3 (3.83 g, 9.60 mmol), DA-4 (3.08 g, 9.60 mmol) and NMP (162 g) were added to a 200 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was stirred at 40° C. for 30 hours to obtain a solution of polyamic acid (PAA-6) having a solids concentration of 12% by mass (viscosity: 400 mPa·s). The Mn of this polyamic acid was 11,050 and the Mw was 28,671.
<Synthesis Example 7>
CA-1 (4.43 g, 19.7 mmol), CA-5 (0.937 g, 3.75 mmol), DA-1 (0.811 g, 7.50 mmol), DA-2 (1.83 g, 7.50 mmol), DA-3 (1.99 g, 5.00 mmol), DA-4 (1.60 g, 5.00 mmol) and NMP (84.4 g) were added to a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was stirred at 40 ° C. for 30 hours to obtain a solution of polyamic acid (PAA-7) having a solids concentration of 12% by mass (viscosity: 370 mPa s). The Mn of this polyamic acid was 11,803 and the Mw was 34,703.
<Synthesis Example 8>
CA-1 (4.48 g, 20.0 mmol), CA-6 (0.841 g, 3.75 mmol), DA-1 (0.811 g, 7.50 mmol), DA-2 (1.83 g, 7.50 mmol), DA-3 (1.99 g, 5.00 mmol), DA-4 (1.60 g, 5.00 mmol) and NMP (84.8 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was stirred at 40 ° C. for 30 hours to obtain a solution of polyamic acid (PAA-8) having a solids concentration of 12% by mass (viscosity: 390 mPa s). The Mn of this polyamic acid was 13,037 and the Mw was 31,731.

The specifications of each polymer synthesized above are shown in Table 1. In Table 1, the numerical values for the tetracarboxylic acid component and diamine component represent the content (parts by mole) of each tetracarboxylic acid component and diamine component relative to 100 parts by mole of the total amount of the diamine components used in each polymerization step.

[Preparation of liquid crystal alignment agent]
Example 1
The solution of polyamic acid (PAA-1) obtained in Synthesis Example 1 was diluted with NMP and BCS, and stirred at 25°C for 2 hours to obtain a liquid crystal alignment agent (AL-1) having a polymer solid content of 4 mass% and a content of NMP of 76 mass% and BCS of 20 mass%, respectively, when the total of all components in the liquid crystal alignment agent is 100 mass%.
<Examples 2 to 5, Comparative Examples 1 to 3>
As shown in Table 2, except for changing the type of polymer used, the same procedure as in Example 1 was carried out to obtain liquid crystal alignment agents (AL-2) to (AL-5), (AL-R1) to (AL-R3).

The liquid crystal alignment agents (AL-1) to (AL-5), (AL-R1) to (AL-R3) obtained as described above were confirmed to be homogeneous solutions without abnormalities such as turbidity or precipitation. The liquid crystal alignment agents obtained were used to evaluate the liquid crystal alignment properties.
[Preparation of FFS driving liquid crystal cell]
A liquid crystal cell having the structure of an FFS mode liquid crystal display element was prepared.

First, a substrate with electrodes was prepared. The substrate was a rectangular glass substrate measuring 30 mm x 50 mm and 0.7 mm thick. An ITO electrode with a solid pattern was formed on the substrate as the first layer, which constituted a common electrode. A SiN (silicon nitride) film formed by CVD (chemical vapor deposition) was formed as the second layer on the first common electrode. The thickness of the second SiN film was 300 nm, which was a thickness that functioned as an interlayer insulating film. A comb-shaped pixel electrode formed by patterning an ITO film was arranged as the third layer on the second SiN film, and two pixels, a first pixel and a second pixel, were formed, each pixel having a size of 10 mm in length and 5 mm in width. This substrate with electrodes had a structure in which the first common electrode and the third pixel electrode were insulated by the second SiN film.

The pixel electrode of the third layer has a comb-like shape with a central portion bent at an internal angle of 160° and multiple electrode lines 3 μm wide arranged in parallel at intervals of 6 μm. One pixel is formed by multiple electrode lines, and has a first region and a second region separated by a line connecting the bent portions.

Next, the liquid crystal alignment agents (AL-1) to (AL-5), (AL-R1) to (AL-R3) obtained in the above examples and comparative examples were each filtered through a filter with a pore size of 1.0 μm, and then applied by spin coating to the above electrode-attached substrate (hereinafter referred to as the electrode substrate) and a glass substrate (hereinafter referred to as the opposing substrate) having a columnar spacer with a height of 4 μm and an ITO film formed on the back surface. After drying for 2 minutes on a hot plate at 80 ° C., it was baked for 20 minutes in a hot air circulation oven at 230 ° C. to form a coating film with a thickness of 100 nm. This coating surface was irradiated with polarized ultraviolet light through a 254 nm bandpass filter and a polarizer at the exposure doses listed in Tables 3 and 4, and further baked for 30 minutes in an IR oven at 230 ° C. to perform an alignment treatment, thereby obtaining a substrate with a liquid crystal alignment film. The liquid crystal alignment film formed on the electrode substrate was subjected to an alignment treatment so that the direction that divides the inner angle of the pixel bend is parallel to the alignment direction of the liquid crystal, and the alignment film formed on the counter substrate was subjected to an alignment treatment so that the alignment direction of the liquid crystal on the electrode substrate coincides with the alignment direction of the liquid crystal on the counter substrate when the liquid crystal cell was produced. The above two substrates were combined into a set, and a sealant (Mitsui Chemicals XN-1500T) was printed on the substrate using a dispenser, and another substrate was attached to the set so that the alignment directions of the liquid crystal alignment films were 0° and faced each other. The attached substrates were then pressed together and heated for 60 minutes in a hot air circulation oven at 150°C to harden the sealant, producing an empty cell. Positive liquid crystal PA-1492 (DIC) was injected into this empty cell by a reduced pressure injection method, and the injection port was sealed to obtain an FFS drive liquid crystal cell. The obtained liquid crystal cell was then heated at 120°C for 1 hour and left overnight at 23°C before being used for evaluation.
[Evaluation of Liquid Crystal Alignment Stability]
This evaluation is for evaluating image retention (also called AC image retention) that occurs due to deterioration of the alignment performance of a liquid crystal alignment film during long-term AC driving.

An AC voltage of ±4.2 V at a frequency of 60 Hz was applied to the FFS driving liquid crystal cell prepared above on a high-luminance backlight (light source: LED, luminance: 20,000 cd/m ² ) with a surface temperature of 40° C. for 120 hours.

Thereafter, the pixel electrode and the common electrode of the liquid crystal cell were shorted, and the liquid crystal cell was left at room temperature (23°C) for one day. The deviation between the alignment direction of the liquid crystal in the first region of the pixel and the alignment direction of the liquid crystal in the second region of the pixel in the non-voltage-applied state was calculated as an angle for the liquid crystal cell that had been subjected to the above treatment. Specifically, the liquid crystal cell was placed between two polarizing plates arranged so that the polarization axes were perpendicular to each other, the backlight was turned on, and the arrangement angle of the liquid crystal cell was adjusted so that the transmitted light intensity of the first region of the first pixel was minimized. The rotation angle required when the liquid crystal cell was rotated so that the transmitted light intensity of the second region of the first pixel was minimized was calculated as an angle Δ. Similarly, the first region and the second region of the second pixel were compared, and the same angle Δ was calculated. Then, the average value of the angles Δ of the first pixel and the second pixel was calculated as the rotation angle Δ of the liquid crystal cell. It can be said that the stability of the liquid crystal alignment is better as the value of this rotation angle Δ is smaller. As the evaluation criteria, when the rotation angle Δ of the liquid crystal cell obtained above was less than 0.08°, it was marked as “◯”, and when it was 0.08° or more, it was marked as “×”. The results are shown in Tables 3 and 4.
[Evaluation of in-plane uniformity of contrast]
The variation in the twist angle of the liquid crystal cell was evaluated using AxoStep manufactured by AXOMETRICS. The liquid crystal cell prepared above was placed on a measurement stage, and the distribution of circular retardance in the pixel plane was measured without applying voltage to calculate 3σ, which is three times the standard deviation σ. It can be said that the smaller the 3σ value, the better the in-plane uniformity. As an evaluation criterion, when the 3σ value was less than 1.70, it was marked as "○", and when it was 1.70 or more, it was marked as "×". The results are shown in Tables 3 and 4.

As shown in Tables 3 and 4, the liquid crystal alignment film obtained from the liquid crystal alignment agent using the tetracarboxylic acid component containing the specific alicyclic tetracarboxylic acid derivative (p1) and the specific alicyclic tetracarboxylic acid derivative (p2) had better liquid crystal alignment stability and in-plane contrast uniformity than the liquid crystal alignment film obtained from the liquid crystal alignment agent not falling under the above.
More specifically, the liquid crystal alignment agents (AL-1) to (AL-3) containing a polymer obtained by using (CA-2) as the specific alicyclic tetracarboxylic acid derivative (p2) showed better properties than the conventional liquid crystal alignment agents (AL-R1) to (AL-R2) that did not use (CA-2). Also, the liquid crystal alignment agents (AL-4) to (AL-5) containing a polymer obtained by using (CA-3) or (CA-4) as the specific alicyclic tetracarboxylic acid derivative (p2) showed better properties than the conventional liquid crystal alignment agent (AL-R3) that used a tetracarboxylic dianhydride (CA-6) having a cyclohexane structure.

1: In-plane electric field type liquid crystal display element, 2: Comb electrode substrate, 2a: Base material, 2b: Linear electrode, 2c: Liquid crystal alignment film, 2d: Base material, 2e: Planar electrode, 2f: Insulating film, 2g: Linear electrode, 2h: Liquid crystal alignment film, 3: Liquid crystal, 4: Counter substrate, 4a: Liquid crystal alignment film, 4b: Base material, L: Electric field line

The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2023-8329, filed on January 23, 2023, are hereby incorporated by reference as the disclosure of the specification of the present invention.

Claims

At least one selected from the group consisting of tetracarboxylic dianhydrides represented by the following formula (T1) and derivatives thereof;
a tetracarboxylic acid component comprising at least one selected from the group consisting of tetracarboxylic acid dianhydrides and derivatives thereof represented by the following formulas (T2-1) to (T2-3);
A liquid crystal aligning agent comprising: a diamine component; and at least one polymer (P) selected from the group consisting of a polyimide precursor obtained using the diamine component and a polyimide which is an imidized product of the polyimide precursor.

(R 1 to R 4 each independently represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group, and at least one of R 1 to R 4 represents a group other than a hydrogen atom as defined above.)
The liquid crystal aligning agent according to claim 1 , wherein the diamine component contains a diamine represented by the following formula (d AL ):

(Ar 1 and Ar 1' each represent a benzene ring, a biphenyl structure, or a naphthalene ring, and one or more hydrogen atoms on the benzene ring, the biphenyl structure, or the naphthalene ring may be substituted with a monovalent group. L 1 and L 1' each represent a single bond, -O-, -C(=O)-, or -O-C(=O)-. A represents -CH 2 -, an alkylene group having 2 to 12 carbon atoms, or a divalent organic group in which at least one of -O-, -C(=O)-O-, and -O-C(=O)- is inserted between the carbon-carbon bonds of the alkylene group. Any hydrogen atom possessed by A may be substituted with a halogen atom.)
The liquid crystal aligning agent according to claim 1, wherein the content of the tetracarboxylic dianhydrides and their derivatives represented by the formulas (T2-1) to (T2-3) is 5 to 50 mol % relative to 1 mol of the tetracarboxylic acid component used in the production of the polymer (P).
The liquid crystal aligning agent according to claim 1, wherein at least two of R 1 to R 4 in said formula (1) represent a group other than a hydrogen atom in said definitions.
The liquid crystal aligning agent according to claim 1, wherein the content of the tetracarboxylic dianhydride represented by the formula (T1) and its derivatives is 50 to 95 mol % relative to 1 mol of the tetracarboxylic acid component used in the production of the polymer (P).
The liquid crystal alignment agent according to claim 1, wherein the diamine component further contains at least one other diamine selected from the group consisting of phenylenediamine, diaminobiphenyl compound, diamine having a diphenyl ether structure, diamine having a tetracarboxylic diimide structure, diamine having an amide bond, diamine having a urea bond, and diamine having the group "-N(D)-" (D represents a protective group which is eliminated by heating and is replaced by a hydrogen atom).
The liquid crystal aligning agent according to claim 2, wherein the content of the diamine represented by the formula (d AL ) is 5 mol % or more relative to 1 mol of the diamine component used in the production of the polymer (P).
The content of the diamine represented by the formula (d AL ) is 90 mol % or less based on 1 mol of the diamine component used in the production of the polymer (P);
The liquid crystal aligning agent according to claim 6, wherein the content of the other diamine is 10 to 95 mol % relative to 1 mol of the diamine component used in the production of the polymer (P).
A liquid crystal alignment film obtained from the liquid crystal alignment agent according to any one of claims 1 to 8.
The liquid crystal alignment film according to claim 9, which is obtained by irradiating the liquid crystal alignment film with polarized ultraviolet light.
A liquid crystal display element comprising the liquid crystal alignment film of claim 9.
A method for manufacturing a liquid crystal display element, comprising the following steps (1) to (4):
Step (1): A step of applying the liquid crystal alignment agent according to any one of claims 1 to 8 to at least one of a first substrate and a second substrate; Step (2): A step of baking the applied liquid crystal alignment agent to obtain a film; Step (3): A step of subjecting the film obtained in step (2) to a photo-alignment treatment; Step (4): A step of disposing a liquid crystal layer between the first substrate and the second substrate so as to be adjacent to the photo-aligned film to prepare a liquid crystal cell.
The method for producing a liquid crystal display element according to claim 12, further comprising a step (3b) of performing a heat treatment between steps (3) and (4).
The method for manufacturing a liquid crystal display element according to claim 13, wherein the liquid crystal display element is an IPS type or FFS type liquid crystal display element.