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

Abstract

To provide a liquid crystal aligning agent capable of obtaining a liquid crystal display element which has high liquid crystal alignment property, suppresses variation in brightness in a plane during black display, and has improved contrast.SOLUTION: The liquid crystal-aligning agent contains at least one polymer (A) of a polyimide precursor having a repeating unit (a1) represented by formula (1) and a specific repeating unit (a2) and an imidized polymer thereof.SELECTED DRAWING: None

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] Liquid crystal display devices have traditionally been widely used as display units for personal computers, smartphones, mobile phones, televisions, etc. Liquid crystal display devices typically include 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, an alignment film that controls the orientation of liquid crystal molecules in the liquid crystal layer, and thin-film transistors (TFTs) that switch electrical signals supplied to the pixel electrodes. Known methods for driving liquid crystal molecules include vertical electric field methods such as the TN method and the VA method, and horizontal electric field methods such as the IPS (In Plane Switching) method and the FFS (Fringe Field Switching) method.

[0003] The most widely used liquid crystal alignment films in industry are prepared by rubbing the surface of a film made of polyamic acid and / or its imidized polyimide formed on an electrode substrate in one direction with a cloth made of cotton, nylon, polyester, or the like. Rubbing is a simple, productive, and industrially useful method. However, as liquid crystal display devices become increasingly sophisticated, precise, and large, various problems have emerged, including scratches on the alignment film surface, dust generation, mechanical force and static electricity, and unevenness within the alignment-treated surface. As an alternative to rubbing, a photoalignment method has been proposed, in which liquid crystal alignment ability is imparted by irradiation with polarized radiation. Photoalignment methods utilizing photoisomerization, photocrosslinking, and photodecomposition have been proposed (see Non-Patent Document 1, Patent Documents 1 and 2).

[0004] A liquid crystal alignment film, which is a component of a liquid crystal display element, is a film for uniformly aligning liquid crystals, and liquid crystal alignment is one of its important properties. However, liquid crystal alignment films obtained by the above-mentioned photoalignment method tend to have lower liquid crystal alignment properties than liquid crystal alignment films obtained by conventional rubbing treatments, and this has limited the range of application of liquid crystal display devices equipped with such liquid crystal alignment films. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 9-297313 [Patent Document 2] International Publication No. 2015 / 050135 Brochure [Non-patent literature]

[0006] [Non-Patent Document 1] "Functional Materials" November 1997 Vol. 17, No. 11, pp. 13-22 Summary of the Invention [Problem to be solved by the invention]

[0007] Furthermore, in actual liquid crystal display elements, the twist angle varies slightly within the plane of the liquid crystal display element due to variations in manufacturing, etc. This in-plane variation causes variations in brightness within the plane of the liquid crystal display element when displaying black. The present invention has been made in view of the above circumstances, and one object of the present invention is to provide a liquid crystal aligning agent that can provide a liquid crystal display element having high liquid crystal alignment properties, suppressing variations in brightness within the plane during black display, and improving contrast. [Means for solving the problem]

[0008] The present inventors have conducted extensive research and found that the above-mentioned problems can be solved by using a liquid crystal aligning agent containing a specific component, and have thus completed the present invention. Specifically, the present invention is summarized as follows.

[0009] A liquid crystal aligning agent characterized by containing at least one polymer (A) selected from the group consisting of polyimide precursors having a repeating unit (a1) represented by the following formula (1) and a repeating unit (a2) represented by the following formula (2), and imidized polymers thereof:

[0010] [ka] (In the formula, R1 to R4 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 and containing a fluorine atom, or a phenyl group, and at least one of R1 to R4 represents a group other than a hydrogen atom as defined above. R and Z each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Y1 represents a divalent organic group represented by the following formula (H):

[0011] [ka] (Q1 represents a divalent organic group having 1 to 18 carbon atoms and having *1-NH-C(=O)-*1 or *1-NH-C(=O)-NH-*1. * represents a bond. *1 represents a bond bonding to a carbon atom.)

[0012] [ka] (In the formula, R1 to R4, R, and Z have the same meanings as in the formula (1). Y2 represents a divalent organic group represented by the following formula (O).)

[0013] [ka] (Ar each independently represents a benzene ring, a biphenyl structure, or a naphthalene ring, and at least one of the two Ar represents a naphthalene ring. Any hydrogen atom on the ring may be replaced with a halogen atom or a monovalent organic group. Q2 is -(CH2) n -(n is an integer of 2 to 18), or the above -(CH2) n represents a group in which part of - is replaced with either -O-, -C(=O)- or -OC(=O)-. * represents a bond. In this specification, when it is obvious that the term is an integer, such as "n is an integer of 2 to 18," the "integer" may be omitted. In addition, * represents a bond in all cases. Boc represents a tert-butoxycarbonyl group. Fmoc represents a 9-fluorenylmethyloxycarbonyl group. [Effects of the Invention]

[0014] According to the present invention, there are provided a liquid crystal display element having high liquid crystal alignment properties and excellent contrast with suppressed in-plane brightness variations during black display, and a liquid crystal aligning agent capable of obtaining the same. DETAILED DESCRIPTION OF THE INVENTION

[0015] <Polymer (A)> The liquid crystal aligning agent of the present invention contains at least one polymer (A) selected from the group consisting of polyimide precursors having a repeating unit (a1) represented by the following formula (1) and a repeating unit (a2) represented by the following formula (2) and imidized polymers thereof. The polymer (A) may be composed of one or more types. By containing the repeating unit (a1) or an imidized structural unit of the repeating unit (a1), the polymer (A) has hydrogen-bonding amide bonds or urea bonds within the molecule, thereby enhancing the heat resistance of the resulting liquid crystal alignment film and suppressing contrast degradation due to variations in the in-plane twist angle of the liquid crystal display device that occur during production. Furthermore, by further containing the repeating unit (a2) or an imidized structural unit of the repeating unit (a2), the polymer (A) has a naphthalene skeleton within the molecule, which has excellent heat resistance and liquid crystal alignment properties. This enhances the heat resistance and liquid crystal alignment properties of the resulting liquid crystal alignment film, allowing for the production of liquid crystal display devices with excellent contrast. Due to the synergistic effects described above, the liquid crystal aligning agent of the present invention allows the production of liquid crystal display devices with high liquid crystal alignment properties and excellent contrast.

[0016] [ka] (In the formula, R1 to R4 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 and containing a fluorine atom, or a phenyl group, and at least one of R1 to R4 represents a group other than a hydrogen atom as defined above. R and Z each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Y1 represents a divalent organic group represented by the following formula (H):

[0017] [ka] (Q1 represents a divalent organic group having 1 to 18 carbon atoms and having *1-NH-C(=O)-*1 or *1-NH-C(=O)-NH-*1. *1 represents a bond bonding to a carbon atom.)

[0018] [ka] (In the formula, R1 to R4, R, and Z have the same meanings as in the formula (1). Y2 represents a divalent organic group represented by the following formula (O).)

[0019] [ka] (Ar each independently represents a benzene ring, a biphenyl structure, or a naphthalene ring, and at least one of the two Ar represents a naphthalene ring. Any hydrogen atom on the ring may be replaced with a halogen atom or a monovalent organic group. Q2 is -(CH2) n -(n is an integer of 2 to 18), or the above -(CH2) n represents a group in which a portion of - is replaced with either -O-, -C(=O)- or -OC(=O)-.

[0020] Specific examples of the alkyl group having 1 to 6 carbon atoms in R1 to R4 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, and an n-pentyl group. Specific examples of the alkenyl group having 2 to 6 carbon atoms in R1 to R4 include a vinyl group, a propenyl group, and a butynyl group, which may be linear or branched. Specific examples of the alkynyl group having 2 to 6 carbon atoms in R1 to R4 include an ethynyl group, a 1-propynyl group, and a 2-propynyl group. Specific examples of the halogen atom in R1 to R4 include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Specific examples of the monovalent organic group having 1 to 6 carbon atoms and containing a fluorine atom in R1 to R4 include a fluoromethyl group and a trifluoromethyl group. From the viewpoint of high photoreactivity, R1 to R4 are hydrogen atoms or methyl groups, preferably at least one of R1 to R4 is a methyl group, more preferably at least two of R1 to R4 are methyl groups, and even more preferably, R1 and R3 are methyl groups, and R2 and R4 are hydrogen atoms. In order to obtain the effects of the present invention satisfactorily, at least one of R1 to R4 represents a group other than a hydrogen atom as defined above. This configuration increases the photoreactivity of the polyimide film and increases the in-plane anisotropy of the resulting liquid crystal alignment film, thereby suppressing a decrease in contrast due to variations in the twist angle within the plane of the liquid crystal display element that occur during production.

[0021] Q1 in the above formula (H) represents a divalent organic group having 1 to 18 carbon atoms and having *1-NH-C(=O)-*1 or *1-NH-C(=O)-NH-*1, and among these, -NH-C(=O)-, -NH-C(=O)-NH-, or a divalent organic group having 2 to 18 carbon atoms and having *1-NH-C(=O)-*1 or *1-NH-C(=O)-NH-*1 is preferred. *1 is defined as in the above formula (H). Specific examples of the divalent organic group having 2 to 18 carbon atoms and having *1-NH-C(=O)-*1 or *1-NH-C(=O)-NH-*1 include a divalent organic group (a1) having 2 to 18 carbon atoms in an alkylene group having 2 to 18 carbon atoms, in which some of the -CH2- groups in the alkylene group are replaced with either *1-NH-C(=O)-*1 or *1-NH-C(=O)-NH-*1, and a divalent organic group (a2) having 2 to 18 carbon atoms in which some of the -CH2- groups in the divalent organic group (a1) are replaced with at least one group selected from the group consisting of -O-, -C(=O)O-, -C=C-, -C≡C-, a cyclohexylene group, and a phenylene group. Among these, from the viewpoint of obtaining the effects of the present invention favorably, the above divalent organic group (a1) or a group in which part of the -CH2- in the above divalent organic group (a1) is replaced with -O- is preferred.

[0022] As the divalent organic group represented by the above formula (H), a divalent organic group represented by any one of the following formulae (h-1) to (h-6) is preferred from the viewpoint of obtaining the effects of the present invention favorably.

[0023] [ka]

[0024] Any hydrogen atom on the ring of Ar in the above formula (O) may be replaced with a halogen atom or a monovalent organic group such as 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, or a monovalent organic group containing 1 to 6 carbon atoms and a fluorine atom. Specific examples of these monovalent organic groups include the structures exemplified above for R1 to R4. As a specific example of the divalent organic group represented by the above formula (O), a divalent organic group represented by any one of the following formulae (o-1) to (o-6) is preferred from the viewpoint of improving the liquid crystal alignment property.

[0025] [ka]

[0026] From the viewpoint of obtaining the effects of the present invention satisfactorily, the polymer (A) may further be at least one polymer selected from the group consisting of polyimide precursors having a repeating unit (a2') represented by the following formula (2') and imidized polymers thereof: [ka] (X 2’ represents a tetravalent organic group, and Y 2’ represents a divalent organic group represented by the following formula (O2). R and Z are the same as those in the above formula (1). [ka] (Ar 2’ represents a benzene ring, and any hydrogen atom on the ring may be replaced by a halogen atom or a monovalent organic group. 2’ is a single bond, -O-, -C(=O)-, -OC(=O)-, -(CH2) n -(n is 2 to 18), or the above -(CH2) n represents a group in which part of - is replaced with -O-, -C(=O)-, or -OC(=O)-. m is an integer of 0 to 2. Ar 2’ , Q 2’ When there are multiple, they may be the same or different.)

[0027] X 2’ Examples of the tetravalent organic group include a tetravalent organic group represented by the following formula (g), a tetravalent organic group represented by any one of the following formulae (X-1) to (X-25), and a tetravalent organic group derived from an aromatic tetracarboxylic dianhydride.

[0028] [ka] (R1, R2, R3, and R4 have the same meanings as R1, R2, R3, and R4 in the above formula (1).)

[0029] [ka] [ka]

[0030] Here, the aromatic tetracarboxylic acid dianhydride refers to an acid dianhydride obtained by intramolecular dehydration of a carboxy group bonded to an aromatic ring such as a benzene ring or a naphthalene ring. Specific examples include a tetravalent organic group represented by any one of the following formulae (Xa-1) to (Xa-2) and a tetravalent organic group represented by any one of the following formulae (Xr-1) to (Xr-7).

[0031] [ka] (x and y each independently represent a single bond, an ether, a carbonyl, an ester, an alkanediyl group having 1 to 10 carbon atoms, 1,4-phenylene, a sulfonyl, or an amido group; j and k are 0 or 1.)

[0032] [ka]

[0033] The tetravalent organic group represented by the above formula (Xa-1) or (Xa-2) may have a structure represented by any one of the following formulae (Xa-3) to (Xa-19).

[0034] [ka]

[0035] [ka]

[0036] Ar in the above formula (O2) 2’ Any hydrogen atom on the ring may be replaced with a monovalent organic group such as 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, or a monovalent organic group having 1 to 6 carbon atoms and containing a fluorine atom. Specific examples of these monovalent organic groups include the structures exemplified above for R1 to R4. As the divalent organic group represented by the above formula (O2), a divalent organic group represented by any one of the following formulae (o2-1) to (o2-11) is preferred from the viewpoint of reducing the occurrence of AC afterimages.

[0037] [ka]

[0038] From the viewpoint of improving adhesion to a sealing agent and voltage retention characteristics, the polymer (A) may further be at least one polymer selected from the group consisting of polyimide precursors having a repeating unit (a3) ​​represented by the following formula (3) and imidized polymers thereof:

[0039] [ka] (In the formula, R and Z are defined as in the formula (1). X3 represents a tetravalent organic group, and Y3 represents a divalent organic group having 6 to 30 carbon atoms and containing the group "-N(D)- (D represents a carbamate protecting group)" in the molecule.)

[0040] Specific examples of X3 include the above X 2’In order to satisfactorily obtain the effects of the present invention, X3 is preferably a tetravalent organic group represented by the above formula (g) or a tetravalent organic group represented by any one of the above formulae (X-1) to (X-25), and more preferably a tetravalent organic group represented by the above formula (g).

[0041] Specific examples of the divalent organic group having 6 to 30 carbon atoms and having the group "-N(D)- (D represents a carbamate protecting group)" in the molecule in Y3 include a divalent organic group having a partial structure represented by the following formula (3-1) or a divalent organic group represented by the following formula (3-2).

[0042] [ka]

[0043] In the formula, Q5 is a single bond, -(CH2) n -(n is 1 to 20), or the -(CH2) n Any -CH2- in - can be -O-, -COO-, -OCO-, -NQ9-, -NQ9CO-, -CONQ9-, -NQ9-CO-NQ 10 -, -NQ9-COO- or -O-COO-, and Q9 and Q 10 each independently represents a hydrogen atom or a monovalent organic group. Q6 and Q7 each independently represent -H, -NHD, -N(D)2, a group having -NHD, or a group having -N(D)2. Q8 represents -NHD, -N(D)2, a group having -NHD, or a group having -N(D)2. D represents a carbamate protecting group, and examples of the carbamate protecting group include a tert-butoxycarbonyl group and a 9-fluorenylmethoxycarbonyl group. However, at least one of Q5, Q6, and Q7 has a carbamate protecting group in the group.

[0044] Specific preferred examples of Y3, from the viewpoint of reducing AC afterimages, include divalent organic groups represented by any of the following formulae (Y3-1) to (Y3-5).

[0045] [ka]

[0046] The polymer (A) may be at least one polymer selected from the group consisting of polyimide precursors having a repeating unit (a4) represented by the following formula (4) in addition to the repeating unit (a1), repeating unit (a2), repeating unit (a2'), and repeating unit (a3) ​​and imidized polymers thereof:

[0047] [ka]

[0048] In the formula, X4 represents a tetravalent organic group, and Y4 represents a divalent organic group. R and Z are respectively defined as R and Z in the above formula (1). However, Y4 represents a divalent organic group having 6 to 30 carbon atoms and having a group "-N(D)- (D represents a carbamate-based protecting group)" in the molecule, or a structure other than the divalent organic group represented by the above formula (O2). When X4 is defined as the tetravalent organic group represented by the above formula (g), Y4 represents a divalent organic group represented by the above formula (H) or a structure other than the divalent organic group represented by the above formula (O). Specific examples of X4 include the structures exemplified for X3.

[0049] Specific examples of X4 include the above X 2’ In order to satisfactorily obtain the effects of the present invention, X4 is preferably a tetravalent organic group represented by the above formula (g) or a tetravalent organic group represented by any one of the above formulas (X-1) to (X-25), and more preferably a tetravalent organic group represented by the above formula (g).

[0050] Specific examples of the divalent organic group for Y4 include a divalent organic group represented by the above formula (H), a divalent organic group represented by the above formula (O), a divalent organic group represented by the above formula (O2), a divalent organic group having 6 to 30 carbon atoms and having the group "-N(D)- (D represents a carbamate protecting group)" in the molecule, a divalent organic group represented by any of the following formulas (g-1) to (g-5), and a divalent organic group derived from a diamine described below (a divalent organic group obtained by removing two amino groups from a diamine). Diamines 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 (hereinafter also referred to as a nitrogen atom-containing structure; however, in the above secondary amino group and tertiary amino group, the amino group is not bonded to a carbamate-based protecting group), 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, 2,4- Diaminobenzoic acid, 2,5-diaminobenzoic acid or 3,5-diaminobenzoic acid, diamines having a carboxy group such as diamine compounds represented by the following formulas (3b-1) to (3b-4), 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 4,4'-diaminobenzophenone, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indan-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl- Diamines having a photopolymerizable group at the terminal such as 1H-inden-6-amine, 2-(2,4-diaminophenoxy)ethyl methacrylate, 2,4-diamino-N,N-diallylaniline, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestanyl 3,5-diaminobenzoate, lanostannyl 3,5-diaminobenzoate, 3,6-bis Diamines having a steroid skeleton such as (4-aminobenzoyloxy)cholestane, diamines represented by any one of the following formulae (V-1) to (V-6), diamines having a siloxane bond such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, diamines having an oxazoline ring structure such as those represented by the following formulae (Ox-1) to (Ox-2), and other divalent organic groups derived from diamines, and groups represented by any one of formulae (Y-1) to (Y-167) described in WO 2018 / 117239.

[0051] [ka] [ka] (In (3b-1) above, A 1 represents a single bond, -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -C2O-, -OCH2-, -COO-, -OCO-, -CON(CH3)- or -N(CH3)CO-, and m1 and m2 each independently represent 0 to 4, and m1 + m2 represents 1 to 4. In formula (3b-2), m3 and m4 each independently represent 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 1 to 5. In formula (3b-4), A 3 and A 4 each independently represents a single bond, -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -C2O-, -OCH2-, -COO-, -OCO-, -CO-N(CH3)- or -N(CH3)-CO-, and m6 is an integer of 1 to 4.

[0052] [ka]

[0053] (In the above formulas (V-1) to (V-6), X v1 ~X v4 , X p1 ~X p2 are each independently -(CH2) a - (a is 1 to 15), -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -CHO-, -CH2-OCO-, -COO-, or -OCO-; X v5 represents -O-, -CHO-, -CHOCO-, -COO-, or -OCO-. Xa represents a single bond, -O-, -NH-, or -O-(CH) m -O- (m is 1 to 6), R v1 ~R v4 , R 1a ~R 1beach 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.

[0054] [ka]

[0055] Examples of the nitrogen atom-containing heterocycle include pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, pyridazine, pyrazine, indole, benzimidazole, purine, quinoline, isoquinoline, naphthyridine, quinoxaline, phthalazine, triazine, carbazole, acridine, piperidine, piperazine, pyrrolidine, hexamethyleneimine, etc. Among these, pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole, and acridine are preferred.

[0056] The secondary amino group and tertiary amino group that the diamine having a nitrogen atom-containing structure may have are represented by, for example, the following formula (n). [ka]

[0057] In the above formula (n), R represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. "*1" represents a bond bonded to the hydrocarbon group. Examples of the monovalent hydrocarbon group represented by R in the above formula (n) include alkyl groups such as methyl, ethyl, and propyl; cycloalkyl groups such as cyclohexyl; and aryl groups such as phenyl and methylphenyl. R is preferably a hydrogen atom or a methyl group.

[0058] Specific examples of diamines having a 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, N,N'-bis(4-aminophenyl)-benzidine, N,N'-bis(4-aminophenyl)-N,N'-dimethylbenzidine, 4,4'-diaminodiphenylamine, N,N-bis(4-aminophenyl)-methylamine, and compounds represented by any of the following formulae (z-1) to (z-28).

[0059] [ka] [ka] [ka] (In the formula, Py represents a pyridine ring or a pyrimidine ring.)

[0060] From the viewpoint of obtaining the effects of the present invention satisfactorily, the sum of the repeating unit (a1) and the imidized structural units of the repeating unit (a1) of the polymer (A) is preferably 1 to 40 mol %, more preferably 1 to 35 mol %, and even more preferably 1 to 30 mol % of all repeating units. Note that this total includes cases where either the repeating unit (a1) or the imidized structural units of the repeating unit (a1) is 0 mol %. Hereinafter, the term "total" also includes cases where one or more of the constituent structural units are 0 mol %.

[0061] From the viewpoint of obtaining the effects of the present invention satisfactorily, the polymer (A) preferably contains the repeating unit (a1), the repeating unit (a2) and their imidized structural units in a total amount of 5 mol % or more, more preferably 10 mol % or more, of all repeating units.

[0062] From the viewpoint of obtaining the effects of the present invention satisfactorily, the sum of the repeating unit (a2) and the imidized structural unit of the repeating unit (a2) in the polymer (A) is preferably 1 to 95 mol %, more preferably 1 to 90 mol %, and even more preferably 5 to 90 mol % of all repeating units.

[0063] From the viewpoint of obtaining the effects of the present invention satisfactorily, the sum of the repeating unit (a3) ​​and the imidized structural unit of the repeating unit (a3) ​​in the polymer (A) is preferably 1 to 40 mol %, more preferably 1 to 30 mol %, and even more preferably 1 to 25 mol % of all repeating units.

[0064] <Polymer (B)> The liquid crystal aligning agent of the present invention may contain, in addition to the polymer (A), a polymer (B) that does not have both the repeating unit (a1) and the repeating unit (a2) in the same molecule. The polymer (B) may be composed of one type or two or more types. From the viewpoint of achieving the effects of the present invention favorably, examples of the polymer (B) include polymers having at least one repeating unit selected from the group consisting of the repeating unit (b1) represented by the following formula (5) and imidized structural units of the repeating unit (b1). The repeating units constituting the polymer (B) may be composed of one type or two or more types. [ka] (In the formula, X5 represents a tetravalent organic group, Y5 represents a divalent organic group, each Z independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, an alkynyl group having 2 to 10 carbon atoms which may have a substituent, a tert-butoxycarbonyl group, or a 9-fluorenylmethoxycarbonyl group, and R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.)

[0065] Examples of the tetravalent organic group in the formula X5 include a tetravalent organic group derived from an aliphatic tetracarboxylic dianhydride, a tetravalent organic group derived from an alicyclic tetracarboxylic dianhydride, or a tetravalent organic group derived from an aromatic tetracarboxylic dianhydride, and specific examples include the tetravalent organic groups exemplified for X4 above. From the viewpoint of achieving the effects of the present invention favorably, X5 is preferably a tetravalent organic group represented by the formula (g) above, a tetravalent organic group represented by any one of the formulae (X-1) to (X-25) above, a tetravalent organic group represented by any one of the formulae (Xa-1) to (Xa-2) above, or a tetravalent organic group represented by any one of the formulae (Xr-1) to (Xr-7) above (these are also collectively referred to as specific tetravalent organic groups).

[0066] In order to obtain the effects of the present invention satisfactorily, the polymer (B) preferably contains repeating units in which X5 is the above-mentioned specific tetravalent organic group in an amount of 5 mol % or more, and more preferably 10 mol % or more, of all repeating units contained in the polymer (B).

[0067] Examples of the divalent organic group in the formula Y5 include the divalent organic groups exemplified for Y4. From the viewpoint of reducing afterimages resulting from residual DC, the polymer (B) is preferably a polymer containing a repeating unit in which Y5 is a divalent organic group selected from the group consisting of the diamine having the nitrogen atom-containing structure, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, the divalent organic group derived from the diamine having a carboxy group, and the divalent organic group represented by the formula (H) (these are also collectively referred to as specific divalent organic groups).

[0068] From the viewpoint of reducing afterimages caused by residual DC, polymer (B) may contain repeating units in which Y5 is the above-mentioned specific divalent organic group in an amount of 1 mol % or more, or 5 mol % or more, of all repeating units contained in polymer (B).

[0069] From the viewpoint of reducing afterimages caused by residual DC, the content ratio of polymer (A) to polymer (B) in terms of the mass ratio of [polymer (A)] / [polymer (B)] may be 10 / 90 to 90 / 10, 20 / 80 to 90 / 10, or 20 / 80 to 80 / 20.

[0070] <Method for producing polymer (A) and polymer (B)> The polyimide precursors (polyamic acid esters, polyamic acids) that are the polymers (A) and (B) used in the present invention, and the polyimides that are imidized polymers thereof, can be synthesized by known methods, for example, as described in International Publication WO2013 / 157586. Specifically, the compound is synthesized by reacting a diamine component with a tetracarboxylic acid derivative component in a solvent (condensation polymerization). Examples of the tetracarboxylic acid derivative component include tetracarboxylic acid dianhydride or its derivatives (tetracarboxylic acid dihalides, tetracarboxylic acid diesters, or tetracarboxylic acid diester dihalides). When the polymer (A) or (B) contains an amic acid structure in part, a polymer (polyamic acid) having an amic acid structure can be obtained by, for example, reacting the tetracarboxylic acid dianhydride component with a diamine component. The solvent is not particularly limited as long as it dissolves the resulting polymer.

[0071] The diamine component and the tetracarboxylic acid derivative component for obtaining the polyimide precursor of polymer (A) are selected and used depending on the repeating units represented by the above formulas (1), (2), (2'), (3), and (4) contained in polymer (A) so as to obtain the structure of such repeating units. For example, when polymer (A) has a repeating unit represented by formula (1), a diamine having a structure of -N(Z)-Y1-N(Z)- (where Y1 and Z are defined as above) is used as the diamine component, and a tetracarboxylic acid derivative having a structure of the following formula (g) (where R1 to R4 are defined as above) is used as the tetracarboxylic acid derivative component. [ka]

[0072] The polyamic acid ester can be obtained by known methods, such as [I] a method of reacting the polyamic acid obtained by the above 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. Methods for obtaining polyimide include thermal imidization, in which a solution containing a polyimide precursor such as polyamic acid or polyamic acid ester obtained by the above reaction is heated as is, and catalytic imidization, in which a catalyst is added to the above solution.

[0073] <Polymer solution viscosity and molecular weight> The polyamic acid, polyamic acid ester, and polyimide used in the present invention preferably have a solution viscosity of, for example, 10 to 1,000 mPa·s when made into a 10 to 15% by mass solution from the viewpoint of workability, but are not particularly limited thereto. The solution viscosity (mPa·s) of the polymer is a value measured at 25°C using an E-type rotational viscometer for a 10 to 15% by mass polymer solution prepared using a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.). The polystyrene-equivalent weight-average molecular weight (Mw) of the polyamic acid, polyamic acid ester, 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), 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. With the molecular weight in this range, good alignment and stability of the liquid crystal display device can be ensured.

[0074] <Liquid crystal alignment agent> The liquid crystal aligning agent of the present invention contains a polymer (A) and, if necessary, a polymer (B). The liquid crystal aligning agent of the present invention may contain other polymers in addition to the polymer (A) and the polymer (B). Examples of the other polymers include polyesters, polyamides, polyureas, polyorganosiloxanes, cellulose derivatives, polyacetals, polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, and poly(meth)acrylates.

[0075] The liquid crystal aligning agent is used to prepare a liquid crystal alignment film, and is in 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. In this case, the concentration of the polymer in the liquid crystal aligning agent can be appropriately changed depending on the thickness of the coating film to be formed. From the viewpoint of forming a uniform and defect-free coating film, the concentration is preferably 1% by mass or more, and from the viewpoint of storage stability of the solution, the concentration is preferably 10% by mass or less. A particularly preferred polymer concentration is 2 to 8% by mass.

[0076] The organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as it can uniformly dissolve the polymer component. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethylpropanamide, and 3-butoxy-N,N-dimethylpropanamide (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 mass %, more preferably 20 to 90 mass %, and particularly preferably 30 to 80 mass %, of the total solvent contained in the liquid crystal aligning agent.

[0077] In addition, the organic solvent contained in the liquid crystal aligning agent is preferably a mixed solvent containing, in addition to the above solvent, a solvent (also called a poor solvent) that improves the coating property when coating the liquid crystal aligning agent and the surface smoothness of the coating film. Specific examples of the poor solvent to be used in combination are listed below, but are not limited to these. 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, 2-(2-butoxy)-2-propanol, Examples of the alkyl esters include (2-ethoxy)-1-propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, ethylene glycol monoacetate, ethylene glycol diacetate, 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).

[0078] 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.

[0079] The content of the poor solvent is preferably 1 to 80 mass % of the total solvent contained in the liquid crystal aligning agent, more preferably 10 to 80 mass %, particularly preferably 20 to 70 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 aligning agent. Preferred solvent combinations of a good solvent and a poor solvent 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-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether, and N-methyl-2-pyrrolidone and γ- Examples include 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, and N-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether.

[0080] The liquid crystal aligning 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 aids for improving 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), compounds for promoting imidization, and dielectrics or conductive substances for adjusting the dielectric constant or electrical resistance of the liquid crystal alignment film.

[0081] From the viewpoint of exhibiting good resistance to AC afterimages and significantly improving film strength, the crosslinkable compound may be at least one compound selected from the group consisting of compounds 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), and a compound represented by the following formula (e) (hereinafter these may be collectively referred to as compound (C)). [ka] In formula (d), R2 and R3 each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH2-OH". * represents a bond. In formula (e), A represents an (m+n)-valent organic group having an aromatic ring, R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, m is 1 to 6, and n is 0 to 4. The aromatic ring of A may be substituted with a monovalent group, and specific examples of the monovalent group include Ar in formula (O2) above. 2’ Examples of the monovalent groups include those shown as the substituents of

[0082] Specific examples of the compound having an oxiranyl group include compounds having two or more oxiranyl groups, such as the compound described in paragraph

[0037] of Japanese Patent Application Laid-Open No. 10-338880 and compounds having a triazine ring skeleton described in International Publication 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 any of the following formulas (r-1) to (r-3), may also be used. [ka]

[0083] 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. 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, and may also be a compound represented by any of the following formulas (bi-1) to (bi-3). [ka]

[0084] Specific examples of compounds having a protected isothiocyanate group include compounds having two or more protected isothiocyanate groups described in JP 2016-200798 A. Specific examples of compounds having a group containing an oxazoline ring structure include compounds containing two or more oxazoline ring structures described in paragraph

[0115] of JP-A No. 2007-286597.

[0085] Specific examples of compounds having a group containing a Meldrum's acid structure include compounds having two or more Meldrum's acid structures described in International Publication WO2012 / 091088. Specific examples of compounds having a cyclocarbonate group include compounds described in International Publication WO2011 / 155577. Examples of the alkyl group having 1 to 3 carbon atoms for R2 and R3 in the group represented by the above formula (d) include a methyl group, an ethyl group, a propyl group, and an isopropyl group.

[0086] 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 International Publication No. WO2015 / 072554 and paragraph

[0058] of Japanese Patent Application Publication No. 2016-118753, and compounds described in Japanese Patent Application Publication No. 2016-200798, and may also be compounds represented by any of the following formulae (hd-1) to (hd-8). [ka]

[0087] Examples of the (m+n)-valent organic group having an aromatic ring in A of 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 group include benzene and naphthalene. Examples of the aromatic heterocycle include the structures exemplified above for the nitrogen-containing heterocycle. 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, a group obtained by removing one hydrogen atom from the alkylene group, and a divalent or trivalent cyclohexane ring. Any hydrogen atom in the alkylene group may be substituted with an organic group such as a fluorine atom or a trifluoromethyl group. Examples of the alkyl group having 1 to 5 carbon atoms for R in the above formula (e) include the alkyl groups exemplified for R1 to R4 in the above formula (1). Specific examples of the above formula (e) include the compounds described in International Publication No. WO2010 / 074269 and compounds represented by any of the following formulae (e-1) to (e-10). [ka]

[0088] 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. Two or more crosslinkable compounds may be combined. 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 more preferably 1 to 15 parts by mass from the viewpoint of promoting the crosslinking reaction and exhibiting good resistance to AC afterimages.

[0089] 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, and N-trimethoxysilylpropyltriethoxysilane. 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 thereof 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.

[0090] The compound for promoting imidization is preferably a compound having a basic site (e.g., a primary amino group, an aliphatic heterocycle (e.g., a pyrrolidine skeleton), an aromatic heterocycle (e.g., an imidazole ring, an indole ring), or a guanidino group) (excluding the crosslinkable compound and adhesion aid), or a compound that generates the basic site upon baking. A compound that generates the basic site upon baking is more preferred, and preferred specific examples include amino acids in which some or all of the basic sites of the amino acid are protected. Specific examples of the amino acid include glycine, alanine, cysteine, methionine, asparagine, glutamine, valine, leucine, phenylalanine, tyrosine, tryptophan, proline, hydroxyproline, arginine, histidine, lysine, and ornithine. A more preferred specific example of the compound for promoting imidization is N-α-(9-fluorenylmethoxycarbonyl)-N-τ-(tert-butoxycarbonyl)-L-histidine.

[0091] <Method of manufacturing liquid crystal alignment film> The method for producing a liquid crystal alignment film using the liquid crystal aligning agent of the present invention is characterized by sequentially carrying out the steps of applying the liquid crystal aligning agent (step (1)), heating the applied liquid crystal aligning agent to obtain a film (step (2)), irradiating the film obtained in step (2) with polarized ultraviolet light (step (3)), and baking the film obtained in step (3) at a temperature of 100°C or higher and higher than that of step (2) (step (4)).

[0092] <Process (1)> The substrate onto which the liquid crystal aligning agent used in the present invention is applied is not particularly limited as long as it is a highly transparent substrate, and glass substrates, silicon nitride substrates, and plastic substrates such as acrylic substrates and polycarbonate substrates can also be used. In this case, it is preferable to use a substrate on which an ITO electrode for driving the liquid crystal is formed from the viewpoint of simplifying the process. Furthermore, 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 light-reflecting material such as aluminum can also be used for the electrode. The method for applying the liquid crystal aligning agent is not particularly limited, but industrially, it is generally performed by screen printing, offset printing, flexographic printing, inkjet printing, etc. Other application methods include a dipping method, a roll coater method, a slit coater method, a spinner method, a spray method, etc., and these may be used depending on the purpose.

[0093] <Process (2)> Step (2) is a step of heating the liquid crystal aligning agent applied to the substrate to form a film. Specifically, the liquid crystal aligning agent applied to the substrate in step (1) can be heated using a heating means such as a hot plate, a heat circulation oven, or an IR (infrared) oven to evaporate the solvent or to thermally imidize the amic acid or amic acid ester in the polymer. The heating step of the liquid crystal aligning agent applied to the substrate in step (1) can be performed at any temperature and for any time, and may be performed multiple times. The heating temperature can be, for example, 40 to 180°C. From the viewpoint of shortening the process, it is preferably 40 to 150°C, and more preferably 40 to 120°C. The heating time is not particularly limited, but can be 1 to 10 minutes or 1 to 5 minutes. When thermally imidizing the amic acid or amic acid ester in the polymer, a heating step can be performed at a temperature range of, for example, 190 to 250°C or 200 to 240°C after the above heating step. The heating time is not particularly limited, but may be 5 to 40 minutes or 5 to 30 minutes.

[0094] <Process (3)> Step (3) is a step of irradiating the film obtained in step (2) with polarized ultraviolet light. The wavelength of the ultraviolet light is preferably 200 to 400 nm, and more preferably, ultraviolet light having a wavelength of 200 to 300 nm is used. In order to improve the liquid crystal alignment, the substrate coated with the liquid crystal alignment film may be irradiated with ultraviolet light while being heated at 50 to 250°C. The irradiation dose of the ultraviolet light is 1 to 10,000 mJ / cm. 2 is preferred, and 100 to 5,000 mJ / cm 2 The liquid crystal alignment film thus prepared can stably align the liquid crystal molecules in a certain direction. The higher the extinction ratio of the polarized UV light, the higher the anisotropy that can be imparted, which is preferable. Specifically, the extinction ratio of linearly polarized UV light is preferably 10:1 or greater, and more preferably 20:1 or greater.

[0095] <Process (4)> Step (4) is a step of firing the film obtained in step (3) at 100°C or higher and at a temperature higher than that in step (2). The firing temperature is not particularly limited as long as it is 100°C or higher and higher than the firing temperature in step (2), but is preferably 150 to 300°C, more preferably 150 to 250°C, and even more preferably 200 to 250°C. The firing time is preferably 5 to 120 minutes, more preferably 5 to 60 minutes, and even more preferably 5 to 30 minutes. The thickness of the liquid crystal alignment film after baking is preferably 5 to 300 nm, more preferably 10 to 200 nm, since if it is too thin, the reliability of the liquid crystal display element may decrease.

[0096] Furthermore, after carrying out either the step (3) or (4) above, the obtained liquid crystal alignment film can be subjected to a contact treatment using water or a solvent. The solvent used in the contact treatment is not particularly limited as long as it dissolves the decomposition products generated from the liquid crystal alignment film upon irradiation with ultraviolet light. Specific examples include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. Among these, water, 2-propanol, 1-methoxy-2-propanol, and ethyl lactate are preferred, and water, 1-methoxy-2-propanol, and ethyl lactate are more preferred, from the viewpoints of versatility and solvent safety. The solvent may be used alone or in combination of two or more.

[0097] Examples of the contact treatment, i.e., treating the liquid crystal alignment film irradiated with polarized UV light with water or a solvent, include immersion treatment and spray treatment (also called spray treatment). The treatment time in these treatments is preferably 10 seconds to 1 hour from the viewpoint of efficiently dissolving decomposition products generated from the liquid crystal alignment film by UV light. In particular, immersion treatment for 1 to 30 minutes is preferred. The solvent during the contact treatment may be at room temperature or heated, but is preferably at 10 to 80°C, more preferably 20 to 50°C. In addition, ultrasonic treatment or the like may be performed as necessary from the viewpoint of the solubility of the decomposition products. After the contact treatment, it is preferable to rinse the liquid crystal alignment film with a low-boiling solvent such as water, methanol, ethanol, 2-propanol, acetone, or methyl ethyl ketone, or to bake the liquid crystal alignment film. Either rinsing or baking may be performed, or both may be performed. The baking temperature is preferably 150 to 300°C, more preferably 180 to 250°C, and even more preferably 200 to 230°C. The baking time is preferably 10 seconds to 30 minutes, more preferably 1 to 10 minutes.

[0098] <Liquid crystal alignment film> The liquid crystal alignment film of the present invention is obtained from the liquid crystal aligning agent. The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film for in-plane switching mode liquid crystal display elements such as IPS mode and FFS mode, and is particularly useful as a liquid crystal alignment film for FFS mode liquid crystal display elements.

[0099] <Liquid crystal display element> The liquid crystal display element of the present invention comprises the above-mentioned liquid crystal alignment film. A liquid crystal display element can be obtained by preparing a substrate with a liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention, and then preparing a liquid crystal cell by a known method, and using the liquid crystal cell. As an example of a method for fabricating a liquid crystal cell, a passive matrix liquid crystal display element will be described below. However, an active matrix liquid crystal display element in which a switching element such as a TFT (Thin Film Transistor) is provided in each pixel portion constituting an image display may also be used.

[0100] Specifically, transparent glass substrates are prepared, and a common electrode is provided on one substrate and segment electrodes are provided on the other substrate. These electrodes can be, for example, ITO electrodes and are patterned to display the desired image. Next, an insulating film is provided on each substrate so as to cover the common electrode and segment electrodes. The insulating film can be, for example, a SiO2-TiO2 film formed by the sol-gel method. Next, a liquid crystal alignment film is formed on each substrate, and one substrate is placed on the other substrate with the liquid crystal alignment film facing each other, and the periphery is bonded with a sealant. Spacers are typically mixed into the sealant to control the gap between the substrates. It is also preferable to spray spacers for controlling the gap between the substrates on the inner surfaces where no sealant is applied. An opening is provided in a portion of the sealant to allow liquid crystal to be filled from the outside. Next, liquid crystal material is injected into the space surrounded by the two substrates and sealant through the opening in the sealant, and the opening is then sealed with an adhesive. The injection can be performed using a vacuum injection method or a method utilizing capillary action in the atmosphere. Either a positive-type or negative-type liquid crystal material can be used as the liquid crystal material. Next, polarizers are installed. Specifically, a pair of polarizers are attached to the surfaces of the two substrates opposite the liquid crystal layer.

[0101] By using the manufacturing method of the present invention, it is possible to suppress image retention caused by long-term AC driving in IPS drive type or FFS drive type liquid crystal display elements. Furthermore, by carrying out heating in a temperature range of 40 to 150°C in step (2) and then carrying out step (3), a liquid crystal alignment film can be obtained with fewer steps than conventional methods. The liquid crystal aligning agent of the present invention can be particularly preferably used in a manufacturing method of a liquid crystal alignment film, which includes a step of removing the organic solvent in a temperature range of 40 to 150°C in step (2) and then carrying out step (3). [Example]

[0102] 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 for compounds and the methods for measuring the respective properties are as follows. (solvent) NMP: N-methyl-2-pyrrolidone BCS: butyl cellosolve, (diamine) DA-1 to DA-12: Compounds represented by the following formulas (DA-1) to (DA-12), (Tetracarboxylic acid dianhydride) CA-1 to CA-2: Compounds represented by the following formulae (CA-1) to (CA-2), (additives) C-1: A compound represented by the following formula (C-1): S-1: a compound represented by the following formula (S-1): F-1: A compound represented by the following formula (F-1):

[0103] [ka]

[0104] [ka]

[0105] [ka]

[0106] <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.)), and deuterated dimethyl sulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) (0.53 mL) was added. The solution was then sonicated to completely dissolve it. Proton NMR at 500 MHz was measured using an NMR spectrometer (JNW-ECA500) (JEOL Datum Co., Ltd.). The imidization ratio was calculated using the integrated peak value of this proton and the integrated peak value of the proton derived from the NH group of the amic acid, which appeared around 9.5 ppm to 10.0 ppm, according to the following equation: Imidization rate (%) = (1 - α x / y) x 100 In the above formula, x is the integrated value of the proton peak derived from the NH group of the amide 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 amide acid in the case of polyamide acid (imidization rate 0%).

[0107] [Polymer synthesis example] <Synthesis Example 1> 9.34 g (38.3 mmol) of DA-1 and 1.60 g (6.75 mmol) of DA-3 were weighed into a 200 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and NMP was added to a concentration of 12% by mass. The mixture was stirred and dissolved under nitrogen. 9.28 g (41.4 mmol) of CA-1 was added to the diamine solution while stirring, and NMP was added to a concentration of 12% by mass. The mixture was stirred at 40°C for 24 hours to obtain a polyamic acid solution. 35 g (9.3 mmol) of the resulting polyamic acid solution was placed in a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and 11.7 g of NMP was added and stirred for 30 minutes. To the resulting solution, 2.86 g of acetic anhydride (3 molar equivalents relative to the polyamic acid) and 0.74 g of pyridine (1 molar equivalent relative to the polyamic acid) were added and heated at 55 °C for 3 hours to perform chemical imidization. The resulting reaction solution was poured into 150 mL of methanol with stirring, and the precipitate was collected by filtration. The same procedure was repeated twice to wash the resin powder, which was then dried under reduced pressure at 60 °C for 12 hours to obtain a polyimide resin powder. The imidization rate of this polyimide resin powder was 71%. 3.60 g of the resulting polyimide resin powder was placed in a 100 mL Erlenmeyer flask, and NMP was added to a solids concentration of 12%. The solution was dissolved by stirring at 70 °C for 24 hours to obtain a polyimide solution (PI-1).

[0108] <Synthesis Examples 2 to 11> Polyimide solutions (PI-2) to (PI-12) were obtained in the same manner as in Synthesis Example 1, except that the types and amounts of monomers used were changed as shown in Table 1 below. In Table 1, the numbers in parentheses indicate the blending ratio (parts by mole) of each compound for the tetracarboxylic acid component relative to 100 parts by mole of the total amount of tetracarboxylic acid derivatives used in the synthesis, and the numbers in parentheses indicate the blending ratio (parts by mole) of each compound for the diamine component relative to 100 parts by mole of the total amount of diamines used in the synthesis. Regarding organic solvents, the numbers indicate the blending ratio (parts by mass) of each organic solvent relative to 100 parts by mass of the total amount of organic solvents used in preparing the polyimide solutions.

[0109] <Synthesis Example 13> 2.69 g (9.0 mmol) of DA-6 and 7.17 g (36.0 mmol) of DA-11 were weighed into a 200 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and NMP was added to a concentration of 12% by mass. The mixture was dissolved by stirring under nitrogen. 12.2 g (41.4 mmol) of CA-2 was added to the diamine solution while stirring, and NMP was added to a concentration of 12% by mass. The mixture was stirred at 70°C for 24 hours to obtain a polyamic acid solution (PAA-1).

[0110] [Table 1]

[0111] [Preparation of liquid crystal alignment agent] <Comparative Example 1> In a sample tube containing a stirrer, the polyimide solution (PI-1) obtained in Synthesis Example 1 and the polyamic acid solution (PAA-1) obtained in Synthesis Example 13 were mixed so that the polymer solids ratio was 50:50 by mass, and NMP and BCS were added to dilute. S-1, C-1, and F-1 were added so that the amounts were 1 part by mass, 10 parts by mass, and 15 parts by mass, respectively, per 100 parts by mass of the total polymer solids, and the mixture was stirred for 30 minutes. After stirring, a liquid crystal alignment agent (R1) was obtained, in which the polymer solids ratio between polyimide (PI-1) and polyamic acid (PAA-1) was 50:50, the polymer solids concentration was 6% by mass, and the solvent composition was NMP:BCS = 80:20 by mass.

[0112] <Comparative Examples 2 to 5, Examples 1 to 14> Liquid crystal aligning agents (R2) to (R5) and liquid crystal aligning agents (1) to (14) were obtained in the same manner as in Comparative Example 1, except that the polymer components used were changed as shown in Table 2 below. In Table 2, the numbers in parentheses for the polymers and additives represent the blending ratio (parts by mass) of each polymer component or additive relative to 100 parts by mass of the total polymer components used in preparing the liquid crystal aligning agent. For the organic solvents, the numbers represent the blending ratio (parts by mass) of each organic solvent relative to 100 parts by mass of the total amount of organic solvents contained in the liquid crystal aligning agent.

[0113] [Table 2]

[0114] Using the liquid crystal alignment agent obtained as described above, an FFS drive liquid crystal cell was fabricated according to the following procedure, and its characteristics were evaluated.

[0115] [Configuration of FFS drive liquid crystal cell] The Fringe Field Switching (FFS) mode liquid crystal cell was constructed by combining a first glass substrate with a finger-on-plate (FOP) electrode layer formed on its surface, consisting of a planar common electrode, an insulating layer, and comb-shaped pixel electrodes, and a second glass substrate with 3.5 μm-high columnar spacers on its surface and an ITO film on its backside for antistatic purposes. The pixel electrodes were comb-shaped, with multiple 3 μm-wide electrode elements bent at a 160° interior angle in the center and arranged parallel to each other at 6 μm intervals. Each pixel had a first and second region, separated by a line connecting the bent portions of the multiple electrode elements. The liquid crystal alignment film formed on the first glass substrate is oriented so that the direction dividing the interior angles of the pixel bends is perpendicular to the alignment direction of the liquid crystal, and the liquid crystal alignment film formed on the second glass substrate is oriented so that the alignment direction of the liquid crystal on the first substrate coincides with the alignment direction of the liquid crystal on the second substrate when the liquid crystal cell is fabricated.

[0116] [Fabrication of liquid crystal cells] A liquid crystal alignment agent filtered through a 1.0 μm filter was applied to the surface of each of the glass substrates by spin coating, and then dried on a hot plate at 80°C for 2 minutes. Then, linearly polarized ultraviolet light with a wavelength of 254 nm and an extinction ratio of 26:1 was applied to the coated surface through a polarizer at a dose of 150 to 350 mJ / cm. 2 The coating was then irradiated and baked in a hot air circulating oven at 230° C. for 30 minutes to obtain two substrates with a liquid crystal alignment film having a thickness of 100 nm. Next, a sealant was printed on one of the pair of substrates with the liquid crystal alignment film, and the other substrate was attached so that the liquid crystal alignment film faces the other substrate. The sealant was then cured to prepare an empty cell. Liquid crystal (MLC-3019, manufactured by Merck) was injected into this empty cell at room temperature using a reduced pressure injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell. The resulting liquid crystal cell was then heated at 120°C for 1 hour and left overnight before being used for various evaluations.

[0117] <Evaluation of liquid crystal alignment> The liquid crystal cells before the ISO treatment were used and the evaluation was carried out by defining those with initial flow alignment as "poor" and those without initial flow alignment as "good". <Evaluation of in-plane contrast uniformity> The twist angle of the liquid crystal display element was evaluated using an OPTIPRO-micro manufactured by Shintech Co., Ltd. The fabricated liquid crystal cell was placed on a measurement stage, and 20 points within the first pixel plane were measured with no voltage applied, and the standard deviation was calculated. The evaluation was performed by defining a twist angle standard deviation of 0.5 or more as "poor" and one less than 0.5 as "good."

[0118] <Evaluation results> Table 3 shows the evaluation results of the liquid crystal display elements obtained using the liquid crystal alignment agents (1) to (14) and (R1) to (R5) obtained in Examples 1 to 14 and Comparative Examples 1 to 5 above.

[0119] [Table 3] [Industrial Applicability]

[0120] The liquid crystal aligning agent of the present invention is widely used in vertical electric field modes such as TN mode and VA mode, and particularly in horizontal electric field modes such as IPS mode and FFS mode liquid crystal display elements.

[0121] The entire contents of the specifications, claims and abstracts of Japanese Patent Application No. 2020-039386 filed on March 6, 2020, and Japanese Patent Application No. 2020-123011 filed on July 17, 2020, are hereby incorporated by reference as the disclosure of the specification of the present invention.

Claims

1. Below Y ４ a repeating unit represented by the following formula (4), which is a divalent organic group represented by the following formula (O2): Below Y ４ a repeating unit represented by the following formula (4), which is a divalent organic group having 6 to 30 carbon atoms and having a group "-N(D)- (D represents a carbamate protecting group)" in the molecule; A liquid crystal alignment film obtained from a liquid crystal aligning agent containing at least one polymer selected from the group consisting of a polyimide precursor having the formula: and an imidized polymer thereof. 【Chemistry 1】 (In formula (4), X ４ represents a tetravalent organic group, and R and Z each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. ４ represents a divalent organic group represented by the following formula (O2) or a divalent organic group having 6 to 30 carbon atoms and having a group "-N(D)- (D represents a carbamate protecting group)" in the molecule, and is not limited to a single bond, -O-, -NH-, -ND-, -(CH ２ ) ｎ -(n is 2 to 18) or -(CH ２ ) ｎ at least one group selected from the group consisting of groups in which a part of - is replaced with any of -O-, -NH-, and -ND-, and -C(=O)-, -O-C(=O)-, or the -(CH ２ ) ｎ - has at least one group selected from the group consisting of groups in which a portion of - has been replaced with any of -C(=O)-, -O-C(=O)-, -NH-C(=O)-, -ND-C(=O)-, -NH-C(=O)-NH-, -ND-C(=O)-NH-, -NH-C(=O)-ND-, and -ND-C(=O)-ND-, provided that divalent organic groups derived from diamines represented by the following formulae D-DA-1 and D-DA-2 are excluded.) 【Chemistry 2】 (In formula (O2), Ar ２’ represents a benzene ring, and any hydrogen atom on the ring may be replaced by a halogen atom or a monovalent organic group. ２’ represents a single bond, -O-, -C(=O)-, -O-C(=O)-, -NH-, -ND-, -(CH ２ ) ｎ -(n is 2 to 18), or the -(CH ２ ) ｎ represents a group in which a part of - is replaced with any of -O-, -C(=O)-, -O-C(=O)-, -NH-, -ND-, -NH-C(=O)-, -ND-C(=O)-NH-, -ND-C(=O)-NH-, -NH-C(=O)-ND-, and -ND-C(=O)-ND-. D represents a carbamate protecting group. m is 0 to 2. Ar ２’ , Q ２’ When there are multiple, they may be the same or different.) 【Transformation 3】

2. The Y ４ a repeating unit represented by formula (4) which is a divalent organic group represented by the following formula (H), The Y ４ a repeating unit represented by formula (4) which is a divalent organic group having 6 to 30 carbon atoms and having a group "-N(D)- (D represents a carbamate protecting group)" in the molecule, The Y ４ and a repeating unit represented by formula (4), which is a divalent organic group represented by the following formula (O): and at least one polymer selected from the group consisting of a polyimide precursor having the repeating unit represented by formula (4), and an imidized polymer thereof. 【Chemistry 4】 (In formula (H), Q １ represents a divalent organic group having 1 to 18 carbon atoms and having the structure *1-NH-C(=O)-*1 or *1-NH-C(=O)-NH-*1. *1 represents a bond bonding to a carbon atom.) 【Transformation 5】 In formula (O), each Ar independently represents a benzene ring, a biphenyl structure, or a naphthalene ring, and at least one of the two Ar represents a naphthalene ring. Any hydrogen atom on the ring may be replaced with a halogen atom or a monovalent organic group. ２ Ha-(CH ２ ) ｎ -(n is an integer of 2 to 18), or the -(CH ２ ) ｎ represents a group in which a portion of - is replaced with -O-, -C(=O)-, or -O-C(=O)-.

3. 3. The liquid crystal alignment film according to claim 1, wherein the imidization rate of the polyimide contained in the polymer is 71% or more.

4. The liquid crystal alignment film according to claim 2 or 3, comprising a polymer (B) other than the polymer, which does not have both a repeating unit represented by formula (4) which is a divalent organic group represented by formula (H) and a repeating unit represented by formula (4) which is a divalent organic group represented by formula (O) in the same molecule.

5. The liquid crystal alignment film according to claim 4, wherein the polymer (B) is a polymer having at least one repeating unit selected from the group consisting of a repeating unit (b1) represented by the following formula (5) and an imidized structural unit of the repeating unit (b1): 【Transformation 6】 (In the formula, X ５ is a tetravalent organic group, and Y ５ is a divalent organic group. Each Z independently represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an alkenyl group having 2 to 10 carbon atoms which may have a substituent, an alkynyl group having 2 to 10 carbon atoms which may have a substituent, a tert-butoxycarbonyl group, or a 9-fluorenylmethoxycarbonyl group. R represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.

6. The Y ５ is a divalent organic group selected from the group consisting of a diamine having a nitrogen atom-containing structure, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, a divalent organic group derived from a diamine having a carboxy group, and a divalent organic group represented by formula (H):

7. 7. The liquid crystal alignment film according to claim 6, wherein the diamine having a nitrogen atom-containing structure is a diamine 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.

8. The liquid crystal alignment film according to claim 7 , wherein the secondary amino group and the tertiary amino group are represented by the following formula (n): 【Transformation 7】 (In formula (n), R represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. "*1" represents a bond bonded to the hydrocarbon group.)

9. The liquid crystal alignment film according to any one of claims 1 to 8, further comprising a crosslinkable compound.

10. The divalent organic group represented by the formula (H) is a divalent organic group represented by any one of the following formulas (h-1) to (h-6): A liquid crystal alignment film according to any one of claims 1 to 9. 【Transformation 8】

11. The divalent organic group represented by the formula (O) is a divalent organic group represented by any one of the following formulas (o-1) to (o-6): A liquid crystal alignment film according to any one of claims 2 to 9. 【Chemistry 9】

12. The divalent organic group having 6 to 30 carbon atoms and having the group "-N(D)- (D represents a carbamate-based protecting group)" in the molecule is a divalent organic group having a partial structure represented by the following formula (3-1), or a divalent organic group represented by the following formula (3-2): The liquid crystal alignment film according to any one of claims 1 to 11. 【Chemistry 10】 (In the formula, Q ５ is a single bond, -(CH ２ ) ｎ -(n is 1 to 20), or the -(CH ２ ) ｎ Any of -CH ２ - is -O-, -COO-, -OCO-, -NQ ９ --, --NQ ９ CO-, -CONQ ９ --, --NQ ９ -CO-NQ １０ --, --NQ ９ is a group substituted with —COO— or —O—COO—, and Q ９ and Q １０ each independently represents a hydrogen atom or a monovalent organic group. Q ６ and Q ７ are each independently -H, -NHD, -N(D) ２ , a group having —NHD, —N(D) ２ represents a group having the formula: ８ -NHD, -N(D) ２ , a group having —NHD, —N(D) ２ D represents a carbamate protecting group. ５ , Q ６ and Q ７ At least one of the groups has a carbamate protecting group in the group.

13. The divalent organic group having 6 to 30 carbon atoms and having the group "-N(D)- (D represents a carbamate-based protecting group)" in the molecule is a structure represented by any one of the following formulas (Y3-1) to (Y3-5): The liquid crystal alignment film according to any one of claims 1 to 12. 【Chemistry 11】 (In each formula, Boc represents a tert-butoxycarbonyl group, and * represents a bond.)

14. The X ４ The liquid crystal alignment film according to any one of claims 1 to 13, wherein is a tetravalent organic group represented by the following formula (g): 【Chemistry 12】 (R １ , R ２ , R ３ , R ４ 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 and containing a fluorine atom, or a phenyl group; R １ ~R ４ At least one of represents a group other than a hydrogen atom as defined above.)

15. In the formula (g), R １ and R ４ is a methyl group, and R ２ and R ３ The liquid crystal alignment film according to claim 14 , wherein is a hydrogen atom.

16. A liquid crystal display device comprising the liquid crystal alignment film according to any one of claims 1 to 15.

17. A method for producing a liquid crystal alignment film according to any one of claims 1 to 15, comprising the following steps (1) and (2): Step (1): A step of heating a liquid crystal alignment agent in a temperature range of 40 to 180° C. to obtain a liquid crystal alignment film. Step (2): A step of irradiating the liquid crystal alignment film obtained in step (1) with polarized ultraviolet light.

18. The method for producing a liquid crystal alignment film according to claim 17, further comprising the following step (3): Step (3): A step of baking at a temperature of 200 to 250°C for 5 to 120 minutes.

19. 19. The method for producing a liquid crystal alignment film according to claim 17, wherein the ultraviolet light has a wavelength of 200 to 300 nm.

20. A liquid crystal display device comprising a liquid crystal alignment film obtained by the method for producing a liquid crystal alignment film according to any one of claims 17 to 19.

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