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

Abstract

Provided is a liquid crystal aligning agent with which a liquid crystal alignment layer having a pretilt angle of at most 1 degree is obtained, and a liquid crystal display element, having a reduced incidence of display defects (line burn-in) even when a negative-type liquid crystal is used as a liquid crystal material, is obtained.　This liquid crystal aligning agent contains a polyimide (A) obtained by imidizing a polyimide precursor, which is a reaction product of a tetracarboxylic acid derivative component and a diamine component, wherein: the tetracarboxylic acid derivative component contains a 1,2,3,4-butane tetracarboxylic dianhydride or a derivative thereof; and the diamine component contains at least one diamine selected from among formulae (1a)-(1b) and a diamine represented by formula (2).　(The meaning of each substituent is as described in the specification.)

Description

[Technical field]

[0001] The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element. [Background technology]

[0002] A liquid crystal display element is constructed by sandwiching a liquid crystal layer between a pair of transparent substrates equipped with electrodes. In the liquid crystal display element, an organic film made of an organic material is used as a liquid crystal alignment film so that the liquid crystal is aligned in a desired state between the substrates. That is, the liquid crystal alignment film is a component of the liquid crystal display element, and is formed on the surface of the substrates that sandwich the liquid crystal and contacts the liquid crystal, and plays a role of aligning the liquid crystal in a certain direction between the substrates. Furthermore, the liquid crystal alignment film can control the pretilt angle of the liquid crystal. Methods of lowering the pretilt angle mainly by selecting a polyimide structure (see Patent Documents 1 and 2) are known. In recent years, with the advancement of performance of liquid crystal display elements, in addition to applications such as large-screen, high-definition liquid crystal televisions, liquid crystal display elements are being used in vehicles, such as car navigation systems, meter panels, and monitors for surveillance cameras and medical cameras. In order to meet the demand for viewing angle characteristics, a lower pretilt angle than conventional ones is now being required even for rubbed alignment films. In particular, the viewing angle dependency of color resulting from the pretilt angle, so-called color shift, has been pointed out as a problem, and in order to solve this problem, a liquid crystal alignment film having a pretilt angle of 1 degree or less has been proposed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-188761 [Patent Document 2] Japanese Patent Application Publication No. 10-123532 [Patent Document 3] International Publication No. 2019-082975 Summary of the Invention [Problem to be solved by the invention]

[0004] In the past, positive-type liquid crystals were used in in-plane switching type liquid crystal display elements such as the IPS driving type and the FFS driving type. However, the use of negative-type liquid crystals makes it possible to reduce the transmission loss above the electrodes and improve contrast, so liquid crystal display elements using negative-type liquid crystals have recently been investigated. However, as a result of investigations conducted by the present inventors, it was found that the use of negative type liquid crystal as the liquid crystal material results in a high incidence of display defects (line burn-in), making it impossible to obtain a liquid crystal display element with excellent display quality. In addition, polyimide-based liquid crystal alignment agents generally use organic polar solvents with high hygroscopicity, such as N-methyl-2-pyrrolidone. Therefore, when a coating film is obtained from a polyimide-based liquid crystal alignment agent containing the above organic solvent, the obtained film tends to be easily affected by the environment in which the coating is performed. In particular, when coating is performed in a high humidity environment, there is a problem that the solubility of polyimide decreases due to moisture absorption, the polyimide precipitates, and the film turns white (hygroscopic whitening). In addition, even if a film that has undergone hygroscopic whitening is dried or heated, there is a problem that the original liquid crystal alignment film properties cannot be obtained, and the obtained film has a rough surface. Furthermore, when a coating film is obtained by flexographic printing using a polyimide-based liquid crystal alignment agent, the polyimide component may precipitate on the flexographic plate, resulting in printing foreign matter, or the polyimide component may precipitate in the ejection head of an inkjet device, causing clogging of the head, leading to defects in the process.

[0005] In view of the above circumstances, the object of the present invention is to provide a liquid crystal aligning agent that can obtain a liquid crystal alignment film having a pretilt angle of 1 degree or less, and at the same time, can obtain a liquid crystal display element with a low incidence of display defects (line burn-in) even when a negative liquid crystal is used as the liquid crystal material. Another object of the present invention is to provide a liquid crystal aligning agent that can suppress the hygroscopic whitening phenomenon, is less likely to cause foreign matter or clogging when obtaining a coating film, and the obtained film has little surface roughness, and furthermore, can exhibit the inherent properties of a liquid crystal alignment film even after drying or heating.

[0006] As a result of extensive investigations to achieve the above object, the inventors have found that a liquid crystal aligning agent having the following composition is optimal for achieving the above object, and have completed the present invention. [Means for solving the problem]

[0007] Thus, the present invention is based on the above findings and has the following gist. A liquid crystal aligning agent containing a polyimide (A) obtained by imidizing a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative component and a diamine component, wherein the tetracarboxylic acid derivative component contains 1,2,3,4-butanetetracarboxylic dianhydride or a derivative thereof, and the diamine component contains at least one diamine selected from the following formulas (1a) to (1b) and a diamine represented by the following formula (2). [ka] In the formula, D represents a divalent saturated hydrocarbon group, unsaturated hydrocarbon group, aromatic hydrocarbon group or heterocycle having 1 to 20 carbon atoms, and D may have one or more substituents. E represents a single bond, or a divalent saturated hydrocarbon group, unsaturated hydrocarbon group, aromatic hydrocarbon group or heterocycle having 1 to 20 carbon atoms, and E may have one or more substituents. F represents a single bond, -O-, -OCO- or -COO-. m is an integer of 0 or 1. A represents an organic group that can be eliminated by heat. The hydrogen atoms of the benzene ring having amino groups at both ends may be substituted with one or more substituents.

[0008] In this specification, Boc represents a tert-butoxycarbonyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Effect of the Invention

[0009] By using the liquid crystal aligning agent of the present invention, a liquid crystal alignment film having a pretilt angle of 1 degree or less can be obtained, and a liquid crystal display element having a low incidence of display defects (line burn-in) can be obtained even when a negative liquid crystal is used as the liquid crystal material. In addition, a liquid crystal aligning agent can be obtained which can suppress the moisture absorption whitening phenomenon, is less likely to cause foreign matter or clogging when obtaining a coating film, has less surface roughness, and can exhibit the inherent properties of a liquid crystal alignment film even after drying or heating. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] <Specific polymer> The polyimide (A) (hereinafter also referred to as the specific polymer) contained in the liquid crystal alignment agent of the present invention is obtained by imidizing a polyimide precursor obtained from a tetracarboxylic acid derivative component containing a specific tetracarboxylic acid dianhydride and a diamine component containing a specific diamine. The polyimide (A) may be composed of one type or two or more types. The polyimide precursor may be a polyamic acid or a derivative thereof (e.g., a polyamic acid ester). Specific examples of the materials used and the manufacturing method will be described in detail below.

[0011] <Tetracarboxylic acid derivatives> The tetracarboxylic acid derivative component used in the production of the specific polymer of the present invention can be not only a tetracarboxylic acid dianhydride but also its derivatives, such as a tetracarboxylic acid dihalide compound, a tetracarboxylic acid dialkyl ester, and a tetracarboxylic acid dialkyl ester dihalide. As the tetracarboxylic acid derivative component, one type of tetracarboxylic acid dianhydride or its derivative may be used alone, or two or more types may be used in combination. The tetracarboxylic acid derivative component contains 1,2,3,4-butanetetracarboxylic dianhydride or a derivative thereof.

[0012] The content of the 1,2,3,4-butanetetracarboxylic dianhydride or a derivative thereof is preferably 50 to 100 mol %, more preferably 50 to 95 mol %, and further preferably 50 to 90 mol %, of the total tetracarboxylic acid derivative components.

[0013] The tetracarboxylic acid derivative component used in the production of the specific polymer contained in the liquid crystal alignment agent of the present invention may be the above-mentioned 1,2,3,4-butanetetracarboxylic dianhydride or its derivative, or various other tetracarboxylic acid derivative components may be used depending on the desired properties of the liquid crystal alignment agent or liquid crystal alignment film. Preferable specific examples thereof include acyclic aliphatic tetracarboxylic dianhydrides or derivatives thereof other than those mentioned above, alicyclic tetracarboxylic dianhydrides or derivatives thereof, and aromatic tetracarboxylic dianhydrides or derivatives thereof. Here, the aromatic tetracarboxylic dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups including at least one carboxy group bonded to an aromatic ring. The acyclic aliphatic tetracarboxylic dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxy groups bonded to a chain hydrocarbon structure. However, it is not necessary to be composed of only a chain hydrocarbon structure, and it may have an alicyclic structure or an aromatic ring structure in part. The alicyclic tetracarboxylic dianhydride is an acid dianhydride 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, it is not necessary to be composed of only an alicyclic structure, and it may have a chain hydrocarbon structure or an aromatic ring structure in part. Among them, the tetracarboxylic acid derivative component is preferably one represented by the following formula (3): The tetracarboxylic acid dianhydride or its derivative represented by the following formula (3) may be used alone or in combination of two or more.

[0014] [ka] X in the formula 1is a structure selected from the following formulas (X1-1) to (X1-25).

[0015] [ka]

[0016] [ka]

[0017] [ka]

[0018] [ka]

[0019] In formulae (X1-1) to (X1-4), R 3 ~R 23 each independently represents 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. * represents a bond. From the viewpoint of liquid crystal alignment, R 3 ~R 23 is preferably a hydrogen atom, a halogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom or a methyl group. In formulae (X1-24) to (X1-25), j and k are integers of 0 or 1; 1 and A 2 each independently represents a single bond, -O-, -CO-, -COO-, phenylene, sulfonyl, or an amide group. 2 may be the same or different.

[0020] Specific examples of formula (X1-1) include the following formulae (X1-1-1) to (X1-1-6). From the viewpoint of improving the liquid crystal alignment property, (X1-1-1) is particularly preferable. * is as defined above.

[0021] [ka]

[0022] Preferred specific examples of the above formulae (X1-24) and (X1-25) include the following formulae (X1-26) to (X1-41), in which * is as defined above. [ka] [ka]

[0023] From the viewpoint of enhancing the liquid crystal alignment, the above X 1 is preferably the above formula (X1-1) to (X1-3), (X1-5), (X1-7) to (X1-9), (X1-10) or (X1-23), and more preferably the above formula (X1-1-1), (X1-1-2), (X1-2) to (X1-3), (X1-5), (X1-7) to (X1-9), (X1-10) or (X1-23).

[0024] <Specific diamine> The diamine component used in the production of the polyimide (A) contained in the liquid crystal aligning agent of the present invention contains at least one diamine selected from the following formulas (1a) to (1b) and a diamine represented by the following formula (2). The diamines represented by the following formulas (1a) to (1b) and (2) may each be used alone or in combination of two or more. [ka] (In the formula, D represents a divalent saturated hydrocarbon group, unsaturated hydrocarbon group, aromatic hydrocarbon group or heterocycle having 1 to 20 carbon atoms, which may have one or more substituents. E represents a single bond, or a divalent saturated hydrocarbon group, unsaturated hydrocarbon group, aromatic hydrocarbon group or heterocycle having 1 to 20 carbon atoms, which may have one or more substituents. F represents a single bond, -O-, -OCO- or -COO-. m is an integer of 0 or 1. A represents an organic group that can be eliminated by heat. The hydrogen atoms of the benzene ring having amino groups at both ends may be substituted with one or more substituents.)

[0025] Examples of the substituent for D or E include a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, a carboxy group, a hydroxy group, an alkyloxycarbonyl group having 1 to 10 carbon atoms, a cyano group, and a nitro group. The organic group that can be detached by heat is not particularly limited as long as it is an organic group that is decomposed by heat and detached, thereby converting -NHA into an amino group. Examples of the structure of the organic group that can be detached by heat include carbamate-based organic groups such as benzyloxycarbonyl group, 9-fluorenylmethyloxycarbonyl group, allyloxycarbonyl group, and tertiary butoxycarbonyl group (tert-butoxycarbonyl group). In terms of being efficiently detached by heat, being detached at a relatively low temperature, and being discharged as a harmless gas when detached, the tertiary butoxycarbonyl group is particularly preferred. In this specification, the organic group is, for example, a hydrocarbon group that may have a nitrogen atom or an oxygen atom.

[0026] In the above formula (1a) or (1b), the hydrogen atom of the benzene ring having amino groups at both ends may be substituted with a substituent, specifically a halogen atom or an alkyl group having 1 to 5 carbon atoms, and is selected from various types depending on the availability of reagents, but unsubstituted ones are preferred. The substitution position of the amino group is not particularly limited, but from the viewpoint of the difficulty of synthesis and the availability of reagents, the meta or para position is preferred based on the amide bond, and from the viewpoint of liquid crystal alignment, the para position is particularly preferred. Similarly, in aminobenzenes that do not have a protected amino group (i.e., -NHA), the meta or para position is preferred based on the amide bond, the meta position is preferred based on solubility, and the para position is preferred based on liquid crystal alignment.

[0027] The saturated hydrocarbon group having 1 to 20 carbon atoms for D and E in the above formula (1a) or (1b) is, for example, -CH 2 -or-(CH 2 ) m - (m is an integer of 2 to 20); a cycloalkylene group such as a cyclobutylene group, a cyclopentylene group, or a cyclohexylene group; or the above -(CH 2 ) m and groups in which part of the carbon-carbon bonds in - have been replaced by the above cycloalkylene groups. Examples of the unsaturated hydrocarbon group include groups in which some of the carbon-carbon bonds in a saturated hydrocarbon group having 2 to 20 carbon atoms have been replaced with double bonds or triple bonds. Examples of the aromatic hydrocarbon group include a benzene ring, a biphenyl structure, and a naphthalene ring. Examples of the heterocycle include nitrogen atom-containing heterocycles such as 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.

[0028] The diamine selected from the above formulae (1a) to (1b) is preferably a diamine selected from the following formulae (1-1) to (1-4). [ka]

[0029] The content of at least one diamine selected from the above formulae (1a) and (1b) is preferably 5 to 50 mol %, more preferably 10 to 50 mol %, and further preferably 10 to 40 mol % of the total diamine components.

[0030] In the above formula (2), the hydrogen atom of the benzene ring having amino groups at both ends may be substituted with a substituent, specifically, for example, a halogen atom or an alkyl group having 1 to 5 carbon atoms, and is selected from various types depending on the availability of reagents, etc., but unsubstituted ones are preferred.

[0031] The diamine represented by the above formula (2) is preferably a diamine represented by the following formulas (2-1) to (2-2). [ka]

[0032] The content of the diamine of the above formula (2) is preferably 50 to 95 mol %, and more preferably 50 to 90 mol %, of the total diamine components.

[0033] In addition to the above diamines, various diamines (hereinafter also referred to as other diamines) can be used as the diamine component used in the production of the polyimide (A) contained in the liquid crystal alignment agent of the present invention depending on the desired properties of the liquid crystal alignment agent. Other diamines include diamines (4) having a structure of the following formula (iv) in the molecule; diamines represented by the following formula (O); diamines having a photoalignment group such as 4,4'-diaminoazobenzene or diaminotolane; diamines having an amide bond or a urea bond such as diamines represented by the following formulas (h-1) to (h-6); 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-aminobenzyl)benzene, and diamines represented by the following formulas (A-1) to (A-6); and at least one nitrogen atom-containing structure selected from the group consisting of a nitrogen atom-containing heterocycle, a secondary amino group, and a tertiary amino group (hereinafter also referred to as a specific nitrogen atom-containing structure).diamines having the formula (3b-1) to (3b-4) below; 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, and diamines having the formula (3b-1) to (3b-4) below. Diamines containing oxy groups; 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indan-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-6-amine; 2-(2,4-diaminophenoxy)ethyl methacrylate and 2,4-diamino-N,N-diallylaniline. diamines having a photopolymerizable group at the end; cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestanyl 3,5-diaminobenzoate, cholestanyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, and 3,6-bis(4-aminobenzoyloxy)cholestane and other steroid skeletons; diamines represented by the following formulas (V-1) to (V-6); diamines having siloxane bonds such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane; diamines having an oxazoline structure such as the following formulas (Ox-1) to (Ox-2); and diamines having two amino groups bonded to a group represented by any of the formulas (Y-1) to (Y-167) described in International Publication No. 2018 / 117239. The other diamines may be used alone or in combination of two or more.

[0034] [ka] (In the above formula (iv), D is an organic group that can be removed by heat. * represents a bond, at least one of which is bonded to an aliphatic hydrocarbon group.)

[0035] [ka] (Ar represents a divalent benzene ring, a biphenyl structure, or a naphthalene ring. Two Ar may be the same or different, and any hydrogen atom on the benzene ring, the biphenyl structure, or the naphthalene ring may be replaced with a monovalent organic group. p is an integer of 0 or 1. Q 2 Ha-(CH 2 ) n -(n is an integer of 2 to 18), or the -(CH 2 ) n -of-CH 2 represents a group in which at least a portion of - has been replaced with -O-, -C(=O)-, or -OC(=O)-.

[0036] [ka]

[0037] [ka]

[0038] [ka] (In formula (3b-1), A 1 is a single bond, -CH 2 -, -C 2 H 4 -, -C(CH 3 ) 2 -, -CF 2 -, -C(CF 3 ) 2 -, -O-, -CO-, -NH-, -N(CH 3 )-, -CONH-, -NHCO-, -CH 2 O-, -OCH 2 -, -COO-, -OCO-, -CON(CH 3 )- or -N(CH 3)CO-, m1 and m2 each independently represent an integer of 0 to 4, and m1+m2 represents an integer of 1 to 4. In formula (3b-2), m3 and m4 each independently represent an integer of 1 to 5. In formula (3b-3), A 2 represents a linear or branched alkyl group having 1 to 5 carbon atoms, and m5 is an integer of 1 to 5. 3 and A 4 are each independently a single bond, -CH 2 -, -C 2 H 4 -, -C(CH 3 ) 2 -, -CF 2 -, -C(CF 3 ) 2 -, -O-, -CO-, -NH-, -N(CH 3 )-, -CONH-, -NHCO-, -CH 2 O-, -OCH 2 -, -COO-, -OCO-, -CON(CH 3 )- or -N(CH 3 )-CO-, and m6 is an integer of 1 to 4.

[0039] [ka] (X v1 ~X v4 , X p1 ~X p2 are each independently -(CH 2 ) a -(a is an integer from 1 to 15), -CONH-, -NHCO-, -CON(CH 3 )-, -NH-, -O-, -CH 2 O-, -CH 2 represents OCO-, -COO-, or -OCO-; X v5 -O-, -CH 2 O-, -CH 2 Xa represents a single bond, -O-, -NH-, or -O-(CH 2 ) m -O- (m represents an integer of 1 to 6), R v1 ~R v4 , R1a ~R 1b each independently represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms. Two k's may be the same or different.

[0040] [ka]

[0041] In the diamine (4) having the structure of the above formula (iv) in the molecule, specific examples of the organic group in D of the above formula (iv) that can be eliminated by heat include the structures exemplified in the above A, including preferred embodiments. From the viewpoint of reducing the incidence of display defects (line burn-in), the above diamine (4) is more preferably an aromatic diamine having one or two benzene rings in the molecule.

[0042] Preferred specific examples of the diamine (4) include diamines represented by the following formulas (4-1) to (4-5). [ka]

[0043] The content of the diamine (4) having the structure of the above formula (iv) in the molecule is preferably 5 to 40 mol %, more preferably 5 to 35 mol %, and further preferably 5 to 30 mol % of the total diamine components.

[0044] In the diamine represented by the above formula (O), any hydrogen atom on the benzene ring, biphenyl structure, or naphthalene ring may be replaced with a monovalent organic group. Examples of the monovalent organic group include a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, a carboxy group, a hydroxy group, an alkyloxycarbonyl group having 1 to 10 carbon atoms, a cyano group, and a nitro group.

[0045] Preferred specific examples of the divalent organic group obtained by removing two amino groups from the diamine represented by the above formula (O) include divalent organic groups represented by the following formulas (o-1) to (o-16), in which * represents a bond.

[0046] [ka]

[0047] [ka] (In formula (o-14), the two m's may be the same or different.)

[0048] [ka]

[0049] Examples of the nitrogen atom-containing heterocycle that may be contained in the diamine having the specific nitrogen atom-containing structure include the heterocycles exemplified above. Among these, pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole, and acridine are preferred.

[0050] The secondary amino group and tertiary amino group that the diamine having the specific nitrogen atom-containing structure may have are represented, for example, by the following formula (n). [ka] In the above formula (n), R represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. "*" represents a bond bonded to the hydrocarbon group.

[0051] Examples of the monovalent hydrocarbon group R in the above formula (n) include alkyl groups such as methyl, ethyl, and propyl groups; cycloalkyl groups such as cyclohexyl groups; and aryl groups such as phenyl and methylphenyl groups. R is preferably a hydrogen atom or a methyl group.

[0052] Specific examples of diamines having the specific nitrogen atom-containing structure include 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, diamines represented by the following formulae (Dp-1) to (Dp-8), and diamines represented by the following formulae (z-1) to (z-18).

[0053] [ka]

[0054] [ka]

[0055] [ka]

[0056] <Polymer (B)> The liquid crystal aligning agent of the present invention may contain a polyimide precursor (B) (hereinafter also referred to as polymer (B)) which is a reaction product of a tetracarboxylic acid derivative component and a diamine component, from the viewpoint of reducing residual images derived from residual DC. The polyimide precursor (B) may be composed of one type or two or more types. Specific examples of the polyimide precursor (B) include polyamic acid or its derivatives (e.g., polyamic acid esters), and among them, polyamic acid is preferable.

[0057] Examples of the tetracarboxylic acid derivative component for obtaining the polymer (B) include acyclic aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, aromatic tetracarboxylic acid dianhydrides, or derivatives thereof. Specific examples of the acyclic aliphatic tetracarboxylic acid dianhydrides, alicyclic tetracarboxylic acid dianhydrides, and aromatic tetracarboxylic acid dianhydrides include the tetracarboxylic acid dianhydrides or derivatives thereof exemplified in the above specific polymer. Among them, preferred tetracarboxylic acid derivative components include 1,2,3,4-butanetetracarboxylic acid dianhydride or its derivatives, tetracarboxylic acid dianhydrides having at least one partial structure selected from the group consisting of a benzene ring, a cyclobutane ring structure, a cyclopentane ring structure, and a cyclohexane ring structure, or derivatives thereof, and more preferred are 1,2,3,4-butanetetracarboxylic acid dianhydride, a compound represented by the above formula (3), or derivatives thereof. As the tetracarboxylic acid derivative component, one type of tetracarboxylic acid dianhydride or its derivative may be used alone, or two or more types may be used in combination.

[0058] The tetracarboxylic acid derivative component for obtaining the polymer (B) is preferably a tetracarboxylic acid dianhydride represented by formula (3) in which X is selected from the above formulas (X1-1) to (X1-10), (X1-21), and (X1-23) to (X1-25), 1,2,3,4-butanetetracarboxylic acid dianhydride, or a derivative thereof.

[0059] The proportion of the tetracarboxylic dianhydride represented by the above formula (3), 1,2,3,4-butanetetracarboxylic dianhydride, or a derivative thereof used is preferably 1 to 100 mol%, more preferably 5 to 100 mol%, and even more preferably 10 to 100 mol%, based on 1 mol of the total tetracarboxylic acid derivative components used in the synthesis of the polymer (B).

[0060] Examples of the diamine component for obtaining the polymer (B) include the diamine components exemplified in the specific polymer. Among them, it is preferable to include at least one diamine selected from the group consisting of a diamine having at least one group selected from the group consisting of a urea bond, an amide bond, a carboxy group, and a hydroxy group in the molecule (hereinafter also referred to as diamine (b1)), and a diamine having the specific nitrogen atom-containing structure (hereinafter also referred to as diamine (b2)). The diamine component may be a single diamine or a combination of two or more diamines.

[0061] The polymer (B) may be composed of one or more polyimide precursors. More preferred specific embodiments of the polymer (B) include at least one polymer (hereinafter also referred to as a copolymer) selected from the group consisting of a polyimide precursor which is a reaction product between a diamine component containing the diamine (b1) and the diamine (b2) and a tetracarboxylic acid derivative component, and a mixture (hereinafter also referred to as a polymer blend) of at least one polymer (B-p1) selected from the group consisting of a polyimide precursor which is a reaction product between a diamine component containing the diamine (b1) and a tetracarboxylic acid derivative component, and at least one polymer (B-p2) selected from the group consisting of a diamine component containing the diamine (b2) and a polyimide precursor which is a reaction product between a tetracarboxylic acid derivative component. The above copolymers or polymer blends may be used alone or in combination.

[0062] In the above copolymer, the amount of diamine (b1) used is preferably 30 to 100 mol %, more preferably 40 to 100 mol %, and further preferably 50 to 100 mol %, based on the total amount of diamine components used to produce polymer (B). In the above copolymer, the amount of diamine (b2) used is preferably 30 to 100 mol %, more preferably 40 to 100 mol %, and further preferably 50 to 100 mol %, based on the total amount of diamine components used to produce polymer (B). In the above polymer blend, the amount of diamine (b1) and diamine (b2) used is preferably 20 to 100 mol % based on the total amount of diamine components used to produce polymer (B-p1) and polymer (B-p2), respectively. The amount of diamine (b1) used is more preferably 20 to 90 mol %, and even more preferably 20 to 80 mol %, based on the total amount of diamine components used to produce polymer (B-p1). The amount of diamine (b2) used is more preferably 20 to 80 mol %, and even more preferably 30 to 80 mol %, based on the total amount of diamine components used to produce polymer (B-p2).

[0063] Specific examples of the diamine (b1) include diamines represented by the above formulas (1a) to (1b), diamines represented by the above formulas (4-1), diamines represented by the above formulas (h-1) to (h-6), 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, and diamines represented by the above formulas (3b-1) to (3b-4).

[0064] Specific examples of the diamine (b2) include the diamines exemplified in the specific polymer. Among them, the diamines represented by the formulas (Dp-1) to (Dp-8) and the diamines represented by the formulas (z-1) to (z-18) are preferred.

[0065] The mass ratio of the content of the polymer (B-p1) to the content of the polymer (B-p2) is preferably from 5 / 95 to 95 / 5, and more preferably from 10 / 90 to 90 / 10.

[0066] From the viewpoint of reducing afterimages caused by residual DC, the content ratio of the specific polymer to polymer (B) in terms of the mass ratio of [specific polymer] / [polymer (B)] is preferably 10 / 90 to 90 / 10, more preferably 20 / 80 to 90 / 10, and particularly preferably 20 / 80 to 80 / 20.

[0067] <Production method of specific polymer, polymer (B)> The polyimide precursor used in the present invention can be synthesized by a known method such as that described in International Publication WO2013 / 157586.

[0068] Moreover, polyimide can be obtained by ring-closing (imidization) the polyimide precursor. The imidization ratio in this specification means the ratio of imide groups to the total amount of imide groups derived from tetracarboxylic dianhydride or its derivatives and carboxyl groups (or its derivatives). In polyimide, the imidization ratio does not necessarily need to be 100%, and can be adjusted arbitrarily depending on the application and purpose. The imidization ratio of polyimide (A), which is a specific polymer used in the present invention, is preferably 20 to 100%, more preferably 50 to 99%, and even more preferably 70 to 99%, from the viewpoint of reducing the occurrence rate of display defects.

[0069] Examples of methods for imidizing the 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.

[0070] The temperature when thermally imidizing the polyimide precursor in a solution is preferably 100 to 400° C., more preferably 120 to 250° C., and it is preferable to carry out the imidization while removing water generated by the imidization reaction from the system.

[0071] The catalytic imidization of the polyimide precursor can be carried out by adding a basic catalyst and an acid anhydride to a solution of the polyimide precursor and stirring at -20 to 250°C, preferably 0 to 180°C. The amount of the basic catalyst is 0.5 to 30 times by mol, preferably 2 to 20 times by mol, the amount of the acid anhydride is 1 to 50 times by mol, preferably 3 to 30 times by mol, the amount of the amic acid group. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, etc., among which pyridine is preferred because it has a suitable basicity for promoting the reaction. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic anhydride, etc., among which acetic anhydride is preferred because it is easy to purify after the reaction. The imidization rate by catalytic imidization can be controlled by adjusting the amount of the catalyst, the reaction temperature, and the reaction time.

[0072] When recovering the polyimide precursor or polyimide produced from the reaction solution of the polyimide precursor or polyimide, the reaction solution may be poured into a solvent to cause precipitation. Examples of the solvent 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. In addition, the polymer precipitated and recovered can be redissolved in an organic solvent and the reprecipitation and recovery operation can be repeated 2 to 10 times to reduce impurities in the polymer. Examples of the solvent in this case include alcohols, ketones, and hydrocarbons, and it is preferable to use three or more solvents selected from these because the efficiency of purification is further improved.

[0073] The molecular weight of the polymer used in the present invention is preferably 5,000 to 1,000,000, more preferably 10,000 to 150,000, in terms of weight average molecular weight measured by GPC (Gel Permeation Chromatography), taking into consideration the strength of the liquid crystal alignment film obtained therefrom, workability during film formation, and coating properties.

[0074] <Terminal Modifier> In synthesizing the specific polymer, polymer (B) in the present invention, a terminal-modified polymer may be synthesized using a suitable terminal modifier together with the above-mentioned tetracarboxylic acid derivative component and diamine component. The terminal-modified polymer has the effect of improving the film hardness of the liquid crystal alignment film obtained by coating and improving the adhesion property between the sealant and the liquid crystal alignment film. Examples of the terminal of the specific polymer, polymer (B) in the present invention include an amino group, a carboxy group, an acid anhydride group, an isocyanate group, or a derivative thereof. The amino group, the carboxy group, the acid anhydride group, and the isocyanate group can be obtained by a normal condensation reaction, and the derivative can be obtained by modifying the terminal, for example, using the following terminal modifier.

[0075] Examples of the terminal modifier include acid monoanhydrides such as acetic anhydride, maleic anhydride, nadic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, compounds represented by the following formulas (m-1) to (m-6), 3-(3-trimethoxysilyl)propyl)-3,4-dihydrofuran-2,5-dione, 4,5,6,7-tetrafluoroisobenzofuran-1,3-dione, and 4-ethynylphthalic anhydride; [ka] Examples of the dicarbonate diester compounds include di-tert-butyl dicarbonate and diallyl dicarbonate; chlorocarbonyl compounds include acryloyl chloride, methacryloyl chloride and nicotinic acid chloride; 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 monoisocyanate compounds include ethyl isocyanate, phenyl isocyanate and naphthyl isocyanate.

[0076] The proportion of the terminal modifier used is preferably 0.01 to 20 parts by mol, and more preferably 0.01 to 10 parts by mol, relative to 100 parts by mol of the total of the diamine components used.

[0077] <Liquid crystal alignment agent> The liquid crystal aligning agent of the present invention contains a specific polymer and, if necessary, a polymer (B). The content of the polymer component contained in the liquid crystal aligning agent of the present invention is preferably 0.1 to 30 mass%, more preferably 3 to 10 mass%. The total content of the specific polymer and the polymer (B) contained in the liquid crystal aligning agent is preferably 1 to 9 mass%, more preferably 1.5 to 9 mass%. The total also includes the case where one or more of the constituent unit elements are 0 mass%. The liquid crystal alignment agent of the present invention may contain other polymers in addition to the specific polymer, polymer (B). Examples of the other polymers include polyimide (B) which is an imidized product of polyimide precursor (B) (excluding polyimide (A) which is a specific polymer), polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivative, polyacetal, polystyrene or its derivative, poly(styrene-phenylmaleimide) derivative, poly(meth)acrylate, etc.

[0078] The liquid crystal aligning agent is used to prepare a liquid crystal alignment film, and takes the form of a coating liquid from the viewpoint of forming a uniform thin film. The liquid crystal aligning agent of the present invention is also preferably a coating liquid containing the above-mentioned polymer component and an organic solvent.

[0079] The organic solvent contained in the liquid crystal alignment agent is not particularly limited as long as the polymer component is uniformly dissolved in the organic solvent. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, 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-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 3-methyl ... Examples of the good solvent include N-propanamide, 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 solvent"). 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.

[0080] In addition, the organic solvent contained in the liquid crystal alignment agent is preferably a mixed solvent containing the above-mentioned solvent and a solvent (also called a poor solvent) that improves the coating property when applying the liquid crystal alignment agent and the surface smoothness of the coating film. Specific examples of the organic solvent to be used in combination are shown below, but are not limited thereto.

[0081] For example, 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-butoxyethane, 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 monobutyl ether, 1-(2-butoxyethoxy)-2-propanol, Examples of the esters include 2-(2-butoxyethoxy)-1-propanol, propylene glycol monomethyl ether acetate, propylene glycol diacetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether 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).

[0082] Of 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, or diisobutyl ketone is preferred.

[0083] Preferred combinations of good and poor solvents include N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether acetate, N-ethyl-2-pyrrolidone, ethylene glycol monobutyl ether and ethylene glycol monobutyl ether acetate, 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-methyl-2-pyrrolidone, γ-butyrolactone and 4-hydroxy-4- Examples of the poor solvent include methyl-2-pentanone and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanone, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisopropyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanol, N-methyl-2-pyrrolidone and γ-butyrolactone and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone and propylene glycol monobutyl ether and dipropylene glycol dimethyl ether, etc. The content of the poor solvent is preferably 1 to 80% by mass of the total solvent contained in the liquid crystal alignment agent, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass. The type and content of the poor solvent are appropriately selected depending on the coating device, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

[0084] The liquid crystal alignment agent of the present invention may additionally contain components other than the polymer component and the organic solvent (hereinafter also referred to as additive components). Examples of such additive components include adhesion assistants for increasing the adhesion between the liquid crystal alignment film and the substrate or between the liquid crystal alignment film and the sealant, compounds for increasing the strength of the liquid crystal alignment film (hereinafter also referred to as crosslinking compounds), dielectrics or conductive substances for adjusting the dielectric constant or electrical resistance of the liquid crystal alignment film, imidization promoters, etc.

[0085] From the viewpoint of exhibiting good resistance to AC image retention (image retention caused by a decrease in the alignment performance of a liquid crystal alignment film that occurs with long-term AC driving) and highly improving film strength, the crosslinkable compound may be a compound having at least one group selected from the group consisting of an oxiranyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Meldrum's acid structure, a cyclocarbonate group, and a group represented by the following formula (d), or a compound selected from compounds represented by the following formula (e) (hereinafter these are also collectively referred to as compound (C)). [ka] (R 2 and R 3 are each independently a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH 2 "-OH". * indicates a bond. A represents an (m+n)-valent organic group having an aromatic ring. m represents an integer of 1 to 6, and n represents an integer of 0 to 4. The aromatic ring of A may be substituted with a monovalent group, and specific examples of the monovalent group include the monovalent organic groups shown as the substituents of Ar in the above formula (O) (excluding alkoxy groups having 1 to 10 carbon atoms).

[0086] Specific examples of the compound having an oxiranyl group include compounds having two or more oxiranyl groups, such as the compounds described in paragraph

[0037] of JP-A-10-338880 and compounds having a triazine ring skeleton described in WO 2017 / 170483. Among these, compounds containing nitrogen atoms, such as N,N,N',N'-tetraglycidyl-m-xylylenediamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N,N,N',N'-tetraglycidyl-p-phenylenediamine, and compounds represented by the following formulas (r-1) to (r-3), may be used.

[0087] [ka]

[0088] Specific examples of the compound having an oxetanyl group include compounds having two or more oxetanyl groups described in paragraphs

[0170] to

[0175] of WO 2011 / 132751.

[0089] Specific examples of the compound having a protected isocyanate group include the compound having two or more protected isocyanate groups described in paragraphs

[0046] to

[0047] of JP 2014-224978 A, and the compound having three or more protected isocyanate groups described in paragraphs

[0119] to

[0120] of WO 2015 / 141598 A. The compound may be any of the compounds represented by the following formulae (bi-1) to (bi-3). [ka]

[0090] Specific examples of compounds having a protected isothiocyanate group include compounds having two or more protected isothiocyanate groups described in JP 2016-200798 A.

[0091] Specific examples of the compound having a group containing an oxazoline ring structure include compounds containing two or more oxazoline structures described in paragraph

[0115] of JP 2007-286597 A.

[0092] Specific examples of the compound having a group containing a Meldrum's acid structure include compounds having two or more Meldrum's acid structures described in WO 2012 / 091088.

[0093] Specific examples of the compound having a cyclocarbonate group include the compounds described in WO 2011 / 155577.

[0094] R of the group represented by the above formula (d) 2 , R 3 Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, and a propyl group.

[0095] Specific examples of the compound having a group represented by the above formula (d) include compounds having two or more groups represented by the above formula (d) described in WO 2015 / 072554 and paragraph

[0058] of JP 2016-118753 A, and compounds described in JP 2016-200798 A. Also include compounds represented by the following formulae (hd-1) to (hd-8). [ka]

[0096] Examples of the (m+n)-valent organic group having an aromatic ring in A of the above formula (e) include an (m+n)-valent aromatic hydrocarbon group having 6 to 30 carbon atoms, an (m+n)-valent organic group to which an aromatic hydrocarbon group having 6 to 30 carbon atoms is bonded directly or via a linking group, and an (m+n)-valent group having an aromatic heterocycle. Examples of the aromatic hydrocarbon include benzene and naphthalene. Examples of the aromatic heterocycle include a pyrrole ring, an imidazole ring, a pyrazole ring, a pyridine ring, a pyrimidine ring, a quinoline ring, an isoquinoline ring, a carbazole ring, a pyridazine ring, a pyrazine ring, a benzimidazole ring, an indole ring, a quinoxaline ring, and an acridine ring. Examples of the linking group include -NR- (R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms), an alkylene group having 1 to 10 carbon atoms, or a group obtained by removing one hydrogen atom from the alkylene group, and a divalent or trivalent cyclohexane ring. Any hydrogen atom of the alkylene group may be substituted with a fluorine atom or an organic group such as a trifluoromethyl group. Specific examples include the compounds described in WO 2010 / 074269 and the compounds represented by the following formulae (e-1) to (e-10). [ka]

[0097] The above compounds are examples of crosslinkable compounds, and are not limited thereto. For example, components other than those described above are disclosed on pages 53

[0105] to 55

[0116] of International Publication No. 2015 / 060357. In addition, two or more types of crosslinkable compounds may be combined.

[0098] The content of the crosslinkable compound in the liquid crystal aligning agent of the present invention is preferably 0.5 to 20 parts by mass relative to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent, and from the viewpoint of proceeding with the crosslinking reaction and exhibiting good resistance to AC afterimages, it is more preferably 1 to 15 parts by mass.

[0099] Examples of the adhesion aid 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, N-ethoxycarbonyl-3-aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxy ... triethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis(oxyethylene)-3-aminopropyltrimethoxysilane, N-bis(oxyethylene)-3-aminopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,Examples of silane coupling agents include 4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris-(trimethoxysilylpropyl)isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatepropyltriethoxysilane. When a silane coupling agent is used, the amount 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, from the viewpoint of exhibiting good resistance to AC afterimages.

[0100] The solid content concentration in the liquid crystal alignment agent (the ratio of the total mass of the components other than the solvent of the liquid crystal alignment agent to the total mass of the liquid crystal alignment agent) is appropriately selected taking into consideration viscosity, volatility, etc., but is preferably in the range of 0.5 to 15 mass%, more 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, in the case of the spin coating method, the solid content is particularly preferably in the range of 1.5 to 4.5 mass%. In the case of the printing method, the solid content is particularly preferably in the range of 3 to 9 mass%, thereby making the solution viscosity in the range of 12 to 50 mPa·s. In the case of the inkjet method, the solid content is particularly preferably in the range of 1 to 5 mass%, thereby making the solution viscosity in the range of 3 to 15 mPa·s.

[0101] <Liquid crystal alignment film / Liquid crystal display element> The liquid crystal alignment film of the present invention is obtained from the above liquid crystal alignment agent. The liquid crystal alignment film of the present invention can be used as a horizontal alignment type or vertical alignment type (VA type) liquid crystal alignment film, and is particularly suitable for a horizontal alignment type liquid crystal display element such as an IPS mode or FFS mode. The liquid crystal display element of the present invention is provided with the above liquid crystal alignment film. The liquid crystal display element of the present invention can be produced, for example, by a method including the following steps (1) to (3). (1) A process of applying a liquid crystal alignment agent onto a substrate 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. In addition, when manufacturing an IPS type or FFS type liquid crystal element, a substrate on which an electrode made of a transparent conductive film or a metal film patterned into a comb tooth shape is provided and an opposing substrate on which no electrode is provided are used. (2) The coating is baked After applying the liquid crystal alignment agent, preliminary heating (pre-baking) is preferably performed first for the purpose of preventing dripping of the applied alignment agent. The pre-baking temperature is preferably 30 to 200°C, more preferably 40 to 150°C, and particularly preferably 40 to 100°C. The pre-baking time is preferably 0.25 to 10 minutes, more preferably 0.5 to 5 minutes. Then, it is preferable to further perform a heating (post-baking) step. The post-baking temperature is preferably 80 to 300°C, more preferably 120 to 250°C. The post-baking time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. The film thickness of the film thus formed is preferably 5 to 300 nm, more preferably 10 to 200 nm.

[0102] The coating film formed in the above step (1) can be used as a liquid crystal alignment film as it is, but the coating film may be subjected to an alignment ability imparting treatment, such as a rubbing treatment in which the coating film is rubbed in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton, or a photoalignment treatment in which the coating film is irradiated with polarized or non-polarized radiation.

[0103] In the photo-alignment treatment, the radiation to be irradiated to the coating film may be, for example, ultraviolet light and visible light containing light with a wavelength of 150 to 800 nm. When the radiation is polarized, it may be linearly polarized or partially polarized. When the radiation used is linearly polarized or partially polarized, the radiation may be applied from a direction perpendicular to the substrate surface, from an oblique direction, or a combination of these. When non-polarized radiation is applied, the radiation is applied in an oblique direction. (3) The process of producing liquid crystal cells Two substrates on which a liquid crystal alignment film is formed are prepared as described above, and liquid crystal is placed between the two substrates arranged opposite each other. Specifically, the following two methods can be mentioned. In the first method, the two substrates are arranged opposite each other with a gap (cell gap) between them so that the liquid crystal alignment films face each other. Next, the peripheries of the two substrates are bonded together using a sealant, and a liquid crystal composition is injected and filled into the substrate surfaces and the cell gap partitioned by the sealant so that it comes into contact with the film surface, and then the injection hole is sealed.

[0104] The second method is a method called ODF (One Drop Fill) method. For example, a UV-curable sealant is applied to a predetermined location on one of the two substrates on which a liquid crystal alignment film is formed, and a liquid crystal composition is dropped at a predetermined number of locations on the liquid crystal alignment film surface. Thereafter, the other substrate is bonded 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 contacted 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 preferable to further remove the flow alignment during liquid crystal filling by heating to a temperature at which the liquid crystal composition used has an isotropic phase and then slowly cooling to room temperature. When the coating films are subjected to a rubbing treatment, the two substrates are disposed opposite each other so that the rubbing directions of the coating films are at a predetermined angle, for example, perpendicular or anti-parallel to each other. The sealing agent may be, for example, an epoxy resin containing a hardener and aluminum oxide spheres as spacers. The liquid crystal may be, for example, a nematic liquid crystal or a smectic liquid crystal, of which nematic liquid crystal is preferred.

[0105] A liquid crystal display element can be obtained by attaching a polarizing plate to the outer surface of the liquid crystal cell as necessary. Examples of the polarizing plate to be attached to the outer surface of the liquid crystal cell include a polarizing plate in which a polarizing film called an "H film" made by absorbing iodine while stretching and aligning polyvinyl alcohol is sandwiched between cellulose acetate protective films, and a polarizing plate made of the H film itself.

[0106] The liquid crystal display element of the present invention can be effectively applied to various devices, and can be used in various display 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. EXAMPLES

[0107] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The abbreviations for compounds and solvents are as follows. (Organic solvent) NMP: N-methyl-2-pyrrolidone GBL: gamma-butyrolactone BCA: Ethylene glycol monobutyl ether acetate

[0108] (Diamine) DA-1 to DA-10: Compounds shown in the following structural formulas

[0109] [ka]

[0110] (Tetracarboxylic acid derivatives) CA-1 to CA-5: Compounds represented by the following structural formulas

[0111] [ka]

[0112] (Additives) AD-1: 3-glycidoxypropyltriethoxysilane AD-2: A compound shown in the following structural formula.

[0113] [ka]

[0114] <Viscosity> In the synthesis examples, the viscosity of the polymer solution was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample amount of 1.1 mL, a cone rotor TE-1 (1°34', R24), and a temperature of 25°C.

[0115] <Measurement of imidization rate of polyimide> The imidization rate of the polyimide in the synthesis example was measured as follows. 30 mg of polyimide powder was placed in an NMR (nuclear magnetic resonance) sample tube (NMR sampling tube standard, φ5 (Kusano Scientific Co., Ltd.)), deuterated dimethyl sulfoxide (DMSO-d6, 0.05 mass% TMS (tetramethylsilane) mixture) (0.53 ml) was added, and ultrasonic waves were applied to completely dissolve the polyimide. This solution was measured by 500 MHz proton NMR using an NMR measurement device (JNW-ECA500) (JEOL Datum Co., Ltd.). The imidization rate was calculated by the following formula, using the proton derived from the 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 ppm to 10.0 ppm. Imidization rate (%) = (1-α·x / y) × 100 In the above formula, x is the integrated value of the proton peak derived from the NH group of the amic acid, y is the integrated value of the peak of the reference proton, and α is the ratio of the number of reference protons to one NH group proton of the amic acid in the case of polyamic acid (imidization rate 0%).

[0116] [Polymer synthesis] (Synthesis Example 1) In a 200mL four-neck flask equipped with a stirrer and nitrogen inlet tube, 8.04g (40.2mmol) of DA-1, 4.36g (10.9mmol) of DA-2, and 12.2g (21.9mmol) of DA-3 were weighed out, 98.4g of NMP was added, and the mixture was dissolved by stirring while feeding nitrogen. While stirring this diamine solution under water cooling, 9.40g (47.4mmol) of CA-1 was added, and 37.6g of NMP was further added, and the mixture was stirred for 2 hours at 50°C under a nitrogen atmosphere. Furthermore, 4.65g (23.7mmol) of CA-2 was added, and 18.6g of NMP was further added, and the mixture was stirred for 2 hours at 23°C under a nitrogen atmosphere to obtain a solution of polyamic acid (PAA-0) (viscosity: 1250mPa·s). 100 g of the above polyamic acid (PAA-0) solution was placed in a 200 mL Erlenmeyer flask containing a stirrer, and the terminal modifier, di-tert-butyl dicarbonate (hereinafter, Boc 2 After adding 1.24 g (5.68 mmol) of polyamic acid (PAA-0-1) and stirring at 40° C. for 15 hours, a solution of terminal-modified polyamic acid (PAA-0-1) was obtained. In a 200 mL Erlenmeyer flask containing a stirrer, 100 g of the above (PAA-0-1) solution was taken, 66.7 g of NMP, 14.2 g of acetic anhydride, and 4.70 g of pyridine were added, and the mixture was stirred at room temperature for 30 minutes, and then reacted at 60°C for 4 hours. The reaction solution was poured into 650 g of methanol, and the resulting precipitate was filtered off. The precipitate was washed with methanol and then dried under reduced pressure at a temperature of 80°C to obtain a polyimide powder (imidization rate: 89%). Furthermore, 9.60 g of this polyimide powder was dispensed into a 100 mL Erlenmeyer flask containing a stirrer, 70.4 g of NMP was added, and the mixture was stirred at 70° C. for 24 hours to dissolve, thereby obtaining a solution of polyimide (SPI-1).

[0117] <Synthesis Examples 2 to 4> The diamines and tetracarboxylic acid derivatives shown in Table 1 were used and the same procedures as in Synthesis Example 1 were carried out to obtain solutions of polyimides (SPI-2) to (SPI-4) shown in Table 1. In Table 1, the numerical values ​​shown under the compound names indicate the mass (g) of the tetracarboxylic acid derivative used in the synthesis for the tetracarboxylic acid derivative component, and the mass (g) of the diamine used in the synthesis for the diamine component. 2 The cases marked with O were carried out in the same manner as in Synthesis Example 1.

[0118] [Table 1]

[0119] <Synthesis Examples 5 to 11> Solutions of polyamic acids (PAA-1) to (PAA-7) shown in Table 2 were obtained by using the diamines and tetracarboxylic acid derivatives shown in Table 2 below and carrying out the same procedure as in Synthesis Example 1. In Table 2, the numerical values ​​shown under the compound names indicate the mass (g) of the tetracarboxylic acid derivative used in the synthesis for the tetracarboxylic acid derivative components, and the mass (g) of the diamine used in the synthesis for the diamine components.

[0120] [Table 2]

[0121] [Preparation of liquid crystal alignment agent] <Examples 1 to 6 and Comparative Examples 1 to 5> The polyamic acid and polyimide solutions obtained in Synthesis Examples 1 to 11 were weighed out in the amounts shown in the table below, and NMP, GBL, BCA, a GBL solution containing 1 mass% of AD-1, and an NMP solution containing 10 mass% of AD-2 were weighed out in the amounts shown in the table below and added with stirring. The mixture was stirred at room temperature for 2 hours to obtain liquid crystal alignment agents (1) to (11).

[0122] [Table 3]

[0123] [Table 4]

[0124] A method for producing a liquid crystal display device for evaluating the pretilt angle and voltage holding ratio will be described below. [Fabrication of liquid crystal display element] First, a substrate with electrodes was prepared. The substrate was a glass substrate with dimensions of 30 mm x 40 mm and a thickness of 1.1 mm. An ITO electrode with a thickness of 35 nm was formed on the substrate, and the electrode had a stripe pattern of 40 mm in length and 10 mm in width. Next, the liquid crystal alignment agent obtained above was filtered through a filter with a pore size of 1.0 μm, and then applied by spin coating to the prepared substrate with the electrodes. After drying for 2 minutes on a hot plate at 80° C., it was baked for 20 minutes in an IR oven at 230° C. to form a coating film with a thickness of 100 nm, and a substrate with a liquid crystal alignment film was obtained. This liquid crystal alignment film was rubbed with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 1000 rpm, moving speed: 20 mm / sec, indentation length: 0.4 mm), and then ultrasonically irradiated in pure water for 1 minute to wash it, and water droplets were removed by air blowing, and then it was dried at 80° C. for 10 minutes to obtain a substrate with a liquid crystal alignment film. Two substrates with this liquid crystal alignment film were prepared, and 4 μm spacers were sprayed on the liquid crystal alignment film surface of one of them, and then a sealant was printed on it, and the other substrate was attached so that the rubbing direction was in the opposite direction and the film surfaces faced each other, and then the sealant was cured to prepare an empty cell. Negative liquid crystal MLC-7026 (Merck) was injected into this empty cell by the reduced pressure injection method, and the injection port was sealed to obtain a liquid crystal cell. The obtained liquid crystal cell was then heated at 120°C for 1 hour and left at 23°C overnight before being used for each evaluation.

[0125] <Pretilt angle> The pretilt angle in the liquid crystal display element was evaluated using an AxoScan Mueller matrix polarimeter manufactured by Optometrics Co., Ltd. The lower the pretilt angle, the better the display.

[0126] <Voltage holding ratio> A voltage of 1V was applied to the liquid crystal display element at 60°C for 60μsec, and the voltage was measured after 500msec to evaluate how long the voltage could be maintained as the voltage retention rate. The higher the voltage retention rate, the better. It is known that an increase in the voltage retention rate, which is one of the electrical properties of a liquid crystal display element, makes it less likely that line burn-in, which is one of the display defects of liquid crystal display elements, will occur.

[0127] For the liquid crystal display elements having liquid crystal alignment films obtained using the liquid crystal aligning agents of Examples 1 to 6 and Comparative Examples 1 to 5, the results of the pretilt angle evaluation and voltage holding ratio evaluation are shown in Table 5 below.

[0128] [Table 5]

[0129] <Evaluation of whitening properties> 0.1 mL of the liquid crystal alignment agents obtained in Examples 1 to 6 and Comparative Examples 1 to 5 was dropped onto a chrome substrate and left to stand in an environment with a temperature of 23° C. and a humidity of 68%. The edge and center of the droplet were observed with an optical microscope, and the time until a precipitate was generated was measured. In this evaluation, the whitening phenomenon is defined as the phenomenon in which the droplets become cloudy white due to precipitation or aggregation of dissolved polyimide. The state in which the droplets are not whitened at all is evaluated as "good", the state in which only the edges of the droplets are whitened is evaluated as "good", and the state in which the entire surface of the droplets is whitened is evaluated as "bad". The longer the time for which the droplets are whitened, the better the result.

[0130] [Table 6]

[0131] By using the liquid crystal alignment agent of the embodiment of the present invention, a liquid crystal alignment film having a pretilt angle of 1 degree or less was obtained, and a liquid crystal display element having a high voltage retention rate (i.e., a liquid crystal display element having a low incidence of display defects (line burn-in)) was obtained even when a negative liquid crystal was used as the liquid crystal material. In addition, by using the liquid crystal alignment agent of the embodiment of the present invention, it is possible to suppress the phenomenon of whitening due to moisture absorption, and it is difficult for foreign matter or clogging to occur when obtaining a coating film, and the obtained film has little surface roughness. Furthermore, even when dried or heated, a liquid crystal alignment agent that can exhibit the original properties of a liquid crystal alignment film can be obtained. [Industrial Applicability]

[0132] A liquid crystal display element prepared using the liquid crystal alignment agent of the present invention can be a liquid crystal display element with excellent display quality, and is suitably used for display elements of various types, represented by horizontal alignment type liquid crystal display elements such as IPS type or FFS type.

[0133] The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2020-071204, filed on April 10, 2020, are hereby incorporated by reference as the disclosure of the specification of the present invention.

Claims

1. A liquid crystal aligning agent containing a polyimide (A) obtained by imidizing a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative component and a diamine component, wherein the tetracarboxylic acid derivative component contains 1,2,3,4-butanetetracarboxylic dianhydride or a derivative thereof, and the diamine component contains at least one diamine selected from the following formulas (1a) to (1b) and a diamine represented by the following formula (2): 【Chemistry 1】 In the formula, D represents a divalent saturated hydrocarbon group, unsaturated hydrocarbon group, aromatic hydrocarbon group or heterocycle having 1 to 20 carbon atoms, and D may have one or more substituents. E represents a single bond, or a divalent saturated hydrocarbon group, unsaturated hydrocarbon group, aromatic hydrocarbon group or heterocycle having 1 to 20 carbon atoms, and E may have one or more substituents. F represents a single bond, -O-, -OCO-, or -COO-. m is an integer of 0 or 1. A represents an organic group that can be eliminated by heat. The hydrogen atoms of the benzene ring having amino groups at both ends may be substituted with one or more substituents.

2. The liquid crystal aligning agent according to claim 1, wherein the content of the diamine of the formula (2) is 50 to 95 mol % based on the diamine component.

3. The liquid crystal aligning agent according to claim 1 or 2, wherein the content of at least one diamine selected from the formulas (1a) to (1b) is 5 to 50 mol % based on the diamine component.

4. The liquid crystal aligning agent according to any one of claims 1 to 3, wherein the content of 1,2,3,4-butanetetracarboxylic dianhydride or a derivative thereof is 50 to 100 mol % based on the tetracarboxylic acid derivative component.

5. The liquid crystal aligning agent according to any one of claims 1 to 4, wherein the polyimide (A) has an imidization rate of 20 to 100%.

6. The liquid crystal aligning agent according to any one of claims 1 to 5, wherein the tetracarboxylic acid derivative component further comprises at least one tetracarboxylic acid dianhydride represented by the following formula (3) or a derivative thereof: 【Chemistry 2】 X in the formula １ is a structure selected from the following structures: 【Chemistry 3】 (R ３ ~R １７ each independently represents 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. * represents a bond.

7. The at least one diamine selected from the formulas (1a) to (1b) is at least one diamine selected from the following formulas (1-1) to (1-4): Liquid crystal aligning agent according to any one of claims 1 to 6. 【Chemistry 4】 (Boc represents a tert-butoxycarbonyl group.)

8. The liquid crystal aligning agent according to any one of claims 1 to 7, wherein the diamine component further contains at least one diamine (4) having a structure represented by the following formula (iv) in the molecule: 【Chemistry 5】 In the above formula (iv), D is an organic group that can be removed by heat. * represents a bond, at least one of which is bonded to an aliphatic hydrocarbon.

9. The liquid crystal aligning agent according to claim 8, wherein the diamine (4) is a diamine selected from structures represented by the following formulas (4-1) to (4-5): 【Chemistry 6】 Boc represents a tert-butoxycarbonyl group.

10. The liquid crystal aligning agent according to any one of claims 1 to 9, further comprising a polyimide precursor (B) which is a reaction product of a tetracarboxylic acid derivative component and a diamine component.

11. The liquid crystal aligning agent according to claim 10, wherein the polyimide precursor (B) is a polyamic acid.

12. The diamine component for obtaining the polyimide precursor (B) contains at least one diamine selected from the group consisting of a diamine (b1) having at least one group selected from the group consisting of a urea bond, an amide bond, a carboxy group, and a hydroxy group in the molecule, and a diamine (b2) having at least one nitrogen atom-containing structure selected from the group consisting of a nitrogen atom-containing heterocycle, a secondary amino group, and a tertiary amino group. The liquid crystal aligning agent according to claim 10 or 11.

13. The liquid crystal aligning agent according to any one of claims 1 to 12, wherein the polyimide (A) and / or the polyimide precursor (B) are terminal-modified polyimide and / or polyimide precursor.

14. The liquid crystal aligning agent according to any one of claims 1 to 13, further comprising a crosslinkable compound and / or an adhesion assistant.

15. A liquid crystal alignment film obtained from the liquid crystal aligning agent according to any one of claims 1 to 14.

16. A liquid crystal display device comprising the liquid crystal alignment film of claim 15.

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