Liquid crystal alignment agent for photoalignment method, liquid crystal alignment film, and liquid crystal display element

Abstract

A liquid crystal aligning agent for optical alignment methods, said liquid crystal aligning agent containing at least one polymer (A) which is selected from the group consisting of polyimide precursors and imidized polymers thereof. The polyimide precursors have at least one repeating unit (a1) that is selected from the group consisting of a repeating unit represented by formula (1-a) and a repeating unit represented by formula (1-i) and at least one repeating unit (a2) that is selected from the group consisting of a repeating unit represented by formula (2-a) and a repeating unit represented by formula (2-i), with the repeating unit (a1) accounting for from 1% by mole to 20% by mole of all repeating units.

Description

[Technical field]

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

[0002] Conventionally, liquid crystal display devices have been widely used as display units for personal computers, smartphones, mobile phones, television receivers, etc. A liquid crystal display device includes, for example, a liquid crystal layer sandwiched between an element substrate and a color filter substrate, pixel electrodes and a common electrode for applying an electric field to the liquid crystal layer, an alignment film for controlling the alignment of liquid crystal molecules in the liquid crystal layer, and thin film transistors (TFTs) for switching electric signals supplied to the pixel electrodes. Known driving methods for liquid crystal molecules include vertical electric field methods such as the Twisted Nematic (TN) method and the Vertical Alignment (VA) method, and horizontal electric field methods such as the In Plane Switching (IPS) method and the Fringe Field Switching (FFS) method.

[0003] At present, the most industrially widespread liquid crystal alignment film is produced by rubbing the surface of a film made of polyamic acid and / or polyimide obtained by imidizing the polyamic acid formed on an electrode substrate in one direction with a cloth such as cotton, nylon, or polyester, which is called a rubbing treatment. The rubbing treatment is a simple and industrially useful method with excellent productivity. However, with the increase in performance, definition, and size of liquid crystal display elements, various problems have become evident, such as scratches on the surface of the alignment film caused by the rubbing treatment, dust generation, effects due to mechanical force and static electricity, and even non-uniformity within the alignment treatment surface. As an alignment treatment method replacing the rubbing treatment, a photoalignment method is known in which liquid crystal alignment ability is imparted by irradiating polarized radiation. As the photoalignment method, methods utilizing photoisomerization reaction, photocrosslinking reaction, photodecomposition reaction, and the like have been proposed (see Non-Patent Document 1 and Patent Document 1).

[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 characteristics. However, the liquid crystal alignment film obtained by the photoalignment method tends to have lower liquid crystal alignment properties than the liquid crystal alignment film obtained by the conventional rubbing treatment, and the range of application of liquid crystal display devices equipped with the liquid crystal alignment film has been limited. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-297313 [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 of the liquid crystal varies slightly within the plane of the liquid crystal display element due to manufacturing variations, etc. This in-plane variation then causes the brightness of the liquid crystal display element when displaying black to vary within the plane. The present invention has been made in consideration of the above circumstances, and has as its object to provide a liquid crystal alignment agent for a photo-alignment method, which can provide a liquid crystal display element having high liquid crystal alignment properties, suppressed brightness variation within the plane during black display, and improved contrast by a photo-alignment method. [Means for solving the problem]

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

[0009] At least one repeating unit (a1) selected from the group consisting of repeating units represented by the following formula (1-a) and repeating units represented by the following formula (1-i), A liquid crystal aligning agent for photoalignment method, comprising at least one repeating unit (a2) selected from the group consisting of repeating units represented by the following formula (2-a) and repeating units represented by the following formula (2-i), and containing at least one polymer (A) selected from the group consisting of polyimide precursors and imidized polymers thereof, the repeating unit (a1) accounting for 1 to 20 mol % of the total repeating units:

[0010] [ka]

[0011] [ka] (In the formula, X1 represents a tetravalent organic group represented by the following formula (B), and X2 represents a tetravalent organic group represented by the following formula (C). R and Z each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. A plurality of R and Z may be the same or different. Y1 and Y2 each independently represent a divalent organic group represented by the following formula (O).

[0012] [ka] (In the formula, R b1 ~R b4 each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms. L1 represents a single bond, -CH2-, -(CH2) n -(n is an integer of 2 to 18), or the -(CH2) n R represents a group in which at least a part of the -CH2- is replaced with -O-, -C(=O)- or -OC(=O)-. c1 ~R c4each 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; R c1 ~R c4 At least one of represents a group other than a hydrogen atom as defined above.

[0013] [ka] (Ar represents a benzene ring, a biphenyl structure, or a naphthalene ring, and two Ar may be the same or different, and any hydrogen atom in the ring may be replaced with a monovalent organic group. Q represents -CH-, -(CH) n -(n is an integer of 2 to 18), or the -(CH2) n represents a group in which at least a part of -CH2- in - is replaced with either -O-, -C(=O)- or -OC(=O)-. p is an integer of 0 or 1. However, when p is 0, Ar represents a biphenyl structure, and when p is 1, at least one of the two Ar represents a naphthalene ring. * represents a bond.)

[0014] In this specification, * represents a bond in all cases. Boc represents a tert-butoxycarbonyl group. Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. Examples of carbamate-based protecting groups include tert-butoxycarbonyl groups and 9-fluorenylmethoxycarbonyl groups. Effect of the Invention

[0015] The liquid crystal alignment agent for photoalignment of the present invention has the repeating unit (a1) and the repeating unit (a2), and contains at least one polymer (A) selected from the group consisting of polyimide precursors and imidized polymers thereof, the polymer (A) comprising 1 to 20 mol % of the total repeating units of the polyimide precursors and imidized polymers thereof. This suppresses variations in brightness within the plane during black display, and provides an effect that a liquid crystal display element having improved contrast can be obtained by the photoalignment method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The liquid crystal aligning agent for photoalignment method (hereinafter, simply referred to as liquid crystal aligning agent) of the present invention will be described.

[0017] <Polymer (A)> The liquid crystal aligning agent of the present invention contains at least one repeating unit (a1) selected from the group consisting of repeating units represented by the following formula (1-a) and repeating units represented by the following formula (1-i), and at least one repeating unit (a2) selected from the group consisting of repeating units represented by the following formula (2-a) and repeating units represented by the following formula (2-i), and contains at least one polymer (A) selected from the group consisting of polyimide precursors and imidized polymers thereof, the repeating unit (a1) accounting for 1 to 20 mol % of the total repeating units. The polymer (A) may be composed of one type or two or more types.

[0018] <Repeating unit (a1)> The repeating unit (a1) of the present invention is at least one repeating unit selected from the group consisting of repeating units represented by the following formula (1-a) and repeating units represented by the following formula (1-i).

[0019] [ka] (In the formula, X1 represents a tetravalent organic group represented by the following formula (B). R and Z each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Two R's and two Z's may be the same or different. Y1 represents a divalent organic group represented by the following formula (O).)

[0020] [ka] (In the formula, R b1 ~R b4 each independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms. L1 represents a single bond, -CH2-, -(CH2) n-(n is an integer of 2 to 18), or the -(CH2) n represents a group in which at least a portion of the -CH2- is replaced with -O-, -C(=O)- or -OC(=O)-.

[0021] [ka] (Ar represents a benzene ring, a biphenyl structure, or a naphthalene ring, and two Ar may be the same or different, and any hydrogen atom in the ring may be replaced with a monovalent organic group. Q represents -CH-, -(CH) n -(n is an integer of 2 to 18), or the -(CH2) n represents a group in which at least a part of the -CH2- in - is replaced with any one of -O-, -C(=O)-, or -OC(=O)-. p is an integer of 0 or 1. However, when p is 0, Ar represents a biphenyl structure, and when p is 1, at least one of the two Ar represents a naphthalene ring.

[0022] Preferred examples of L1 are a single bond, -CH2- or -(CH2) from the viewpoint of efficiently obtaining the effects of the present invention. n -(n is an integer from 2 to 18). R b1 ~R b4 A preferred example of is a hydrogen atom, from the viewpoint of efficiently obtaining the effects of the present invention.

[0023] From the viewpoint of improving liquid crystal alignment properties, the tetravalent organic group represented by the formula (B) is preferably a tetravalent organic group represented by the following formulas (b-1) to (b-2).

[0024] [ka]

[0025] Preferred examples of the divalent organic group represented by the formula (O) are the divalent organic groups represented by the following formulae (o-1) to (o-7) from the viewpoint of efficiently obtaining the effects of the present invention.

[0026] [ka]

[0027] <Repeating unit (a2)> The repeating unit (a2) of the present invention is at least one repeating unit selected from the group consisting of repeating units represented by the following formula (2-a) and repeating units represented by the following formula (2-i).

[0028] [ka] (In the formula, X2 represents a tetravalent organic group represented by the following formula (C). R and Z each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Two R's and two Z's may be the same or different. Y2 has the same meaning as Y1 above, including preferred specific examples.)

[0029] [ka] (In the formula, R c1 ~R c4 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; R c1 ~R c4 At least one of represents a group other than a hydrogen atom as defined above.

[0030] Examples of the tetravalent organic group represented by formula (C) include tetravalent organic groups represented by the following formulae (Xc-1) to (Xc-6). Among these, (Xc-1) is preferred from the viewpoint of improving liquid crystal alignment properties.

[0031] [ka]

[0032] <Repeating unit (a3)> The polymer (A) may be at least one selected from the group consisting of polyimide precursors having, in addition to the repeating units (a1) and (a2), at least one repeating unit (a3) ​​selected from the group consisting of repeating units represented by the following formula (3-a) and repeating units represented by the following formula (3-i), and imidized polymers thereof:

[0033] [ka] (In the formula, X3 represents a tetravalent organic group, and Y3 represents a divalent organic group represented by the following formula (3d). R and Z are the same as those in the formula (1-a).)

[0034] [ka] (Ar3 represents a benzene ring or a biphenyl structure, and two Ar3 may be the same or different, and any hydrogen atom on the ring may be replaced with a monovalent organic group. Q3 is -(CH2) n -(n is an integer of 2 to 18), or the -(CH2) n represents a group in which at least a portion of the -CH2- is replaced with -O-, -C(=O)- or -OC(=O)-.

[0035] Examples of the divalent organic group represented by the formula (3d) include, but are not limited to, divalent organic groups represented by the following formulas (3d-1) to (3d-8).

[0036] [ka]

[0037] The polymer (A) may be at least one selected from the group consisting of polyimide precursors having at least one kind of repeating unit (a4) selected from the group consisting of repeating units represented by the following formula (4-a) and repeating units represented by the following formula (4-i), in addition to the repeating units (a1) and (a2), and imidized polymers thereof.

[0038] [ka] (In the formula, R and Z are the same as those in the formula (1-a). X4 represents a tetravalent organic group, and Y4 represents 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.)

[0039] Specific examples of the 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 in Y4 include a divalent organic group having a partial structure represented by the following formula (4-1) or a divalent organic group represented by the following formula (4-2).

[0040] [ka]

[0041] In the formula, Q5 is a single bond, -(CH2) n -(n is an integer from 1 to 20), or -(CH2) n Any -CH2- in - can be -O-, -COO-, -OCO-, -NQ9-, -NQ9-CO-, -CO-NQ9-, -NQ9-CO-NQ 10 -, -NQ9-COO- or -O-COO-; 10 each independently represents a hydrogen atom or a monovalent organic group; Q6 and Q7 each independently represent -H, a group having -NHD, or a group having -N(D)2. Q8 represents a group having -NHD, or a group having -N(D)2. D represents a carbamate-based protecting group. However, at least one of Q5, Q6, and Q7 has a carbamate-based protecting group in the group. Q9 and Q 10 Specific examples of the monovalent organic group in the formula (I) include 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, an alkyl group having 1 to 6 carbon atoms and containing a fluorine atom, the above-mentioned carbamate-based protecting groups, and an alkoxyalkyl group having 1 to 6 carbon atoms.

[0042] Here, examples of Y4 include structures represented by the following formulae (Y4-1) to (Y4-4), but are not limited thereto.

[0043] [ka]

[0044] The polymer (A) may be at least one selected from the group consisting of polyimide precursors having at least one kind of repeating unit (a5) selected from the group consisting of repeating units represented by the following formula (5-a) and repeating units represented by the following formula (5-i), in addition to the repeating units (a1) and (a2), and imidized polymers thereof.

[0045] [ka] In formula (5-a) and formula (5-i), R and Z are the same as those in formula (1-a). X5 represents a tetravalent organic group, and Y5 represents a divalent organic group. However, Y5 represents a structure other than the divalent organic group represented by formula (3d) or the 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, and when X5 is the same as the tetravalent organic group represented by formula (B) or the tetravalent organic group represented by formula (C), Y5 represents a structure other than the divalent organic group represented by formula (O).

[0046] In the formula (5-a) and the formula (5-i), specific examples of Y5 include p-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, m-phenylenediamine, 2,4-dimethyl-m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,4'-diaminobiphenyl, and 3,3'-dimethyl-4,4'-diaminobiphenyl. nyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-difluoro-4,4'-diaminobiphenyl, 3,3'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 3,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 2,2'-diaminobiphenyl, 2,3'-diaminobiphenyl, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3, Examples of the divalent organic group include divalent organic groups obtained by removing two amino groups from aromatic diamines such as 4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 4,4'-diaminobenzanilide, 4,4'-diaminoazobenzene, 1,5-diaminonaphthalene, 1,6-diaminonaphthalene, 1,7-diaminonaphthalene, 2,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,7-diaminonaphthalene, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, and 1,4-bis(4-aminobenzyl)benzene, as well as divalent organic groups exemplified by Y6 described later.

[0047] The structure of the tetravalent organic group of X3, X4, and X5 is not particularly limited, and any structure can be independently selected. Preferred specific examples include the following formulae (X1-1) to (X1-44).

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] [ka]

[0053] [ka] In formulae (X1-1) to (X1-4), R 3 ~R 23 are each independently 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. 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.

[0054] Specific examples of formula (X1-1) include the following formulas (X1-1-1) to (X1-1-6): In terms of liquid crystal alignment properties and photoreaction sensitivity, (X1-1-1) to (X1-1-2) are more preferred, and (X1-1-2) is particularly preferred.

[0055] [ka]

[0056] In order to obtain the effects of the present invention satisfactorily, the polymer (A) preferably contains the repeating unit (a1) in an amount of 1 to 20 mol %, more preferably 1 to 15 mol %, of all repeating units.

[0057] To obtain the effects of the present invention satisfactorily, the polymer (A) preferably contains the repeating units (a1) and (a2) in total at 5 mol % or more, more preferably 10 mol % or more, of all repeating units.

[0058] To obtain the effects of the present invention satisfactorily, the polymer (A) preferably contains 1 to 95 mol %, more preferably 1 to 90 mol %, and even more preferably 5 to 90 mol % of the repeating units (a3) ​​based on the total repeating units. In this case, the sum of the repeating units (a1) and (a2) is preferably 99 mol % or less, more preferably 95 mol % or less.

[0059] To obtain the effects of the present invention satisfactorily, the polymer (A) contains the repeating unit (a4) in an amount of preferably 1 to 40 mol %, more preferably 1 to 30 mol %, and even more preferably 1 to 25 mol %, of the total repeating units.

[0060] <Polymer (B)> The liquid crystal aligning agent of the present invention may contain a polymer (B) having a repeating unit represented by the following formula (6) from the viewpoint of reducing residual images derived from residual DC. The polymer (B) does not have the repeating unit (a1) and the repeating unit (a2) in the same molecule. The polymer (B) may be composed of one or more types, and the repeating units constituting the polymer (B) may be composed of one or more types.

[0061] [ka] (X6 is a tetravalent organic group, and Y6 is a divalent organic group. R 、 Z has the same meaning as in formula (1-a).

[0062] The tetravalent organic group in the formula X6 includes a tetravalent organic group derived from an acyclic aliphatic tetracarboxylic dianhydride, a tetravalent organic group derived from an alicyclic tetracarboxylic dianhydride, a tetravalent organic group derived from an aromatic tetracarboxylic dianhydride, etc. Specific examples of the tetravalent organic group derived from an acyclic aliphatic tetracarboxylic dianhydride and the tetravalent organic group derived from an alicyclic tetracarboxylic dianhydride include structures selected from the following formulae (x-1) to (x-13).

[0063] [ka] (In the above formulas (x-1) to (x-13), R 1 ~R 4 R 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 and a fluorine atom, or a phenyl group. 5 and R 6 each independently represents a hydrogen atom or a methyl group.

[0064] The above formula (x-1) is preferably one selected from the group consisting of the following formulas (x1-1) to (x1-6).

[0065] [ka] In the above formulae (x1-1) to (x1-6), *1 represents a bond bonded to one acid anhydride group, and *2 represents a bond bonded to the other acid anhydride group.

[0066] The aromatic tetracarboxylic acid dianhydride is an acid dianhydride obtained by intramolecular dehydration of a carboxyl group bonded to an aromatic ring such as a benzene ring, a naphthalene ring, etc. Specific examples include the tetravalent organic groups represented by the above formulas (X1-28) to (X1-40).

[0067] The divalent organic group in the formula Y6 includes a diamine having at least one nitrogen atom-containing structure (hereinafter also referred to as a nitrogen atom-containing structure) selected from the group consisting of a nitrogen atom-containing heterocycle, a secondary amino group, and a tertiary amino 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, 3,5-diaminobenzoic acid, and the following compounds represented by the formulae (3b-1) to (3b-4): ), 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 4,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylether, 4,4'-diaminobenzanilide, 4,4'-diaminoazobenzene, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indan-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H- Diamines having a urea bond such as indene-6-amine and 1,3-bis(4-aminophenethyl)urea, diamines having a photopolymerizable group at the end such as 2-(2,4-diaminophenoxy)ethyl methacrylate and 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, 3,5-diaminobenzoic acid laminyl, Examples of the diamine include diamines having a steroid skeleton such as nostanyl and 3,6-bis(4-aminobenzoyloxy)cholestane, diamines represented by the following formulas (V-1) to (V-8), diamines having a siloxane bond such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, diamines having an oxazoline structure such as the following formulas (Ox-1) to (Ox-2), and divalent organic groups obtained by removing two amino groups from diamines such as these, and groups represented by any of the formulas (Y-1) to (Y-167) described in WO 2018 / 117239.

[0068] [ka] (In formula (3b-1), A 1 represents a single bond, -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -CHO-, -OCH2-, -COO-, -OCO-, -CON(CH3)- or N(CH3)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 represents an integer of 1 to 5. 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-, -CHO-, -OCH2-, -COO-, -OCO-, -CON(CH3)- or -N(CH3)CO-, and m6 represents an integer of 1 to 4.

[0069] [ka] (X v1 ~X v4 , X p1 ~X p2 are each independently -(CH2) a -(a is an integer of 1 to 15), -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -CHO-, -CHOCO-, -COO-, or -OCO-; v5 represents -O-, -CH2O-, -CH2OCO-, -COO-, or -OCO-. X a is a single bond, -O-, -NH-, -O-(CH2) m -O- (m represents an integer of 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. X V7 ~X V8 each independently represents -O-, -CHO-, -COO- or -OCO-.

[0070] [ka]

[0071] 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, or acridine is preferred.

[0072] The secondary amino group and tertiary amino group that the diamine having a nitrogen atom-containing structure may have are represented, for example, by the following formula (n).

[0073] [ka] 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.

[0074] Examples of the monovalent hydrocarbon group of the above formula R 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.

[0075] 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 the following formulae (z-1) to (z-23).

[0076] [ka]

[0077] [ka]

[0078] [ka]

[0079] From the viewpoint of reducing the afterimage caused by residual DC, it is preferable that polymer (B) is a polymer containing a repeating unit in which Y6 is a divalent organic group (collectively referred to as a specific divalent organic group) selected from the group consisting of diamines having a nitrogen atom-containing structure, 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, the above-mentioned diamines having a carboxy group, or the above-mentioned diamines having a urea bond, from which two amino groups have been removed.

[0080] From the viewpoint of reducing afterimages caused by residual DC, polymer (B) may contain repeating units in which Y6 is the 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).

[0081] 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.

[0082] <Methods of producing polyamic acid, polyamic acid ester, and polyimide> The polyimide precursors, ie, polyamic acid ester, polyamic acid and polyimide, used in the present invention can be synthesized by known methods such as those described in WO 2013 / 157586. Specifically, it is synthesized by reacting a diamine component with a tetracarboxylic acid derivative component in a solvent (condensation polymerization). The tetracarboxylic acid derivative component may be tetracarboxylic acid dianhydride or a derivative thereof (tetracarboxylic acid dihalide, tetracarboxylic acid diester, or tetracarboxylic acid diester dihalide). When a part of the polymer (A) or (B) contains an amic acid structure, for example, a polymer having an amic acid structure (polyamic acid) can be obtained by reacting a tetracarboxylic acid dianhydride component with a diamine component. The solvent is not particularly limited as long as it dissolves the produced polymer.

[0083] The diamine component and the tetracarboxylic acid derivative component for obtaining the polyimide precursor of the polymer (A) are selected and used according to the repeating units represented by the above-mentioned formulas (1-a), (2-a), and, if necessary, the repeating units represented by the formulas (3-a), (4-a), and (5-a) contained in the polymer (A) so as to obtain the structure of such repeating units. For example, when the polymer (A) has a repeating unit represented by formula (1-a), a diamine having a structure of -N(Z)-Y1-N(Z)- (wherein Y1 and Z are defined as above) is used as the diamine component, and a tetracarboxylic acid derivative having a structure represented by the following formula is used as the tetracarboxylic acid derivative component.

[0084] [ka] (The definition of X1 is the same as above.)

[0085] The polyamic acid ester can be obtained by a known method, for example, [I] a method of reacting the polyamic acid obtained by the above-mentioned method with an esterifying agent, [II] a method of reacting a tetracarboxylic acid diester with a diamine, or [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine.

[0086] 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. In the polyimide used in the present invention, the ring closure rate of the amic acid groups (also called the imidization rate) does not necessarily need to be 100%, and can be adjusted as desired depending on the application or purpose. For example, the imidization rate of the polyimide may be 20 to 100%, 50 to 99%, or 70 to 99%, from the viewpoint of increasing the solubility of the polyimide varnish.

[0087] <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 1000 mPa·s when made into a solution of 10 to 15% by mass from the viewpoint of workability, but are not particularly limited thereto. The solution viscosity (mPa·s) of the above polymer is a value measured at 25°C using an E-type rotational viscometer for a polymer solution of 10 to 15% by mass prepared using a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0088] 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), which is expressed as the ratio of Mw to the polystyrene-equivalent number average molecular weight (Mn) measured by GPC, is preferably 15 or less, and more preferably 10 or less. With the molecular weight in this range, good alignment and stability of the liquid crystal display element can be ensured.

[0089] <Liquid crystal alignment agent> The liquid crystal alignment agent of the present invention contains a polymer (A) and, if necessary, a polymer (B). The liquid crystal alignment 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.

[0090] 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. 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 concentration of the polymer is 2 to 8% by mass.

[0091] The organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as the polymer component can be uniformly dissolved therein. Specific examples thereof include N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N-methyl-2-pyrrolidone, N-ethyl-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, N-cyclohexyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, γ-valerolactone, 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 them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide or γ-butyrolactone is preferable. The content of the good solvent is preferably 20 to 99 mass % of the total solvent contained in the liquid crystal alignment agent, more preferably 20 to 90 mass %, and particularly preferably 30 to 80 mass %.

[0092] 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.

[0093] 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-butoxyethoxy)-1-propanol, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol 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, diisobutyl ketone (2,6-dimethyl-4-heptanone), and the like.

[0094] 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.

[0095] Preferred combinations of good and poor solvents include N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and ethylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone and propylene glycol monobutyl ether, N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone and diethylene glycol diethyl ether, and N-methyl-2-pyrrolidone and γ-butyrolactone. Examples of the poor solvent include propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanone, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and diisopropyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether and 2,6-dimethyl-4-heptanol, 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. The content of the poor solvent is preferably 1 to 80 mass % of the total solvent contained in the liquid crystal alignment agent, more preferably 10 to 80 mass %, and particularly preferably 20 to 70 mass %. The type and content of the poor solvent are appropriately selected depending on the coating device, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

[0096] 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), compounds for promoting imidization, and dielectrics and conductive substances for adjusting the dielectric constant and electrical resistance of the liquid crystal alignment film.

[0097] From the viewpoint of exhibiting good resistance to AC afterimages 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 formula (d), or a compound selected from compounds represented by the following formula (e) (hereinafter these are collectively referred to as compound (C)).

[0098] [ka] (R2 and R3 each independently represent a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or "*-CH2-OH". 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. R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. The hydrogen atom on the aromatic ring of A 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.)

[0099] 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.

[0100] [ka]

[0101] 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.

[0102] 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 JP2014-224978A, and the compound having three or more protected isocyanate groups described in paragraphs

[0119] to

[0120] of WO2015 / 141598A. Alternatively, the compound may be one of the compounds represented by the following formulae (bi-1) to (bi-3).

[0103] [ka]

[0104] Specific examples of compounds having a protected isothiocyanate group include compounds having two or more protected isothiocyanate groups described in JP2016-200798A.

[0105] Specific examples of the compound having a group containing an oxazoline ring structure include compounds containing two or more oxazoline ring structures described in paragraph

[0115] of JP-A-2007-286597.

[0106] 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.

[0107] Specific examples of the compound having a cyclocarbonate group include the compounds described in WO 2011 / 155577.

[0108] Examples of the alkyl group having 1 to 3 carbon atoms for R2 and R3 in the group represented by formula (d) include a methyl group, an ethyl group, and a propyl group.

[0109] Specific examples of the compound having a group represented by formula (d) include compounds having two or more groups represented by formula (d) described in WO 2015 / 072554 and paragraph

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

[0110] [ka]

[0111] Examples of the (m+n)-valent organic group having an aromatic ring in A of the 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 an alkylene group having 1 to 10 carbon atoms, -NR- (R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms), a group in which one hydrogen atom has been removed 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 of the compound represented by formula (e) include the compounds described in International Publication No. 2010 / 074269 and the compounds represented by the following formulas (e-1) to (e-10).

[0112] [ka]

[0113] 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.

[0114] 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.

[0115] 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.

[0116] The compound for promoting the 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, etc.) (excluding the crosslinkable compound and the adhesion aid), or a compound that generates the basic site when baked. More preferably, it is a compound that generates the basic site when baked, and a preferred specific example is an amino acid in which a part or all of the basic site of the amino acid is 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 the imidization is N-α-(9-fluorenylmethoxycarbonyl)-N-τ-(tert-butoxycarbonyl)-L-histidine.

[0117] <Method of manufacturing liquid crystal alignment film> The method for producing a liquid crystal alignment film using the liquid crystal alignment agent of the present invention is characterized by sequentially carrying out the steps of applying the above-mentioned liquid crystal alignment agent (step (1)), baking the applied liquid crystal alignment agent (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 at a temperature higher than that of step (2) (step (4)).

[0118] <Process (1)> The substrate to which the liquid crystal alignment agent used in the present invention is applied is not particularly limited as long as it is a highly transparent substrate, and a glass substrate, a silicon nitride substrate, a plastic substrate such as an acrylic substrate or a polycarbonate substrate, etc. 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. 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 light-reflecting material such as aluminum can be used for the electrode.

[0119] The method of applying the liquid crystal alignment agent is not particularly limited, but in industry, it is generally performed by screen printing, offset printing, flexographic printing, inkjet printing, etc. Other application methods include a dip 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.

[0120] <Process (2)> Step (2) is a step of baking the liquid crystal alignment agent applied on the substrate to form a film. After the liquid crystal alignment agent is applied on the substrate, the solvent can be evaporated or the amic acid or amic acid ester in the polymer can be thermally imidized by a heating means such as a hot plate, a heat circulation type oven, or an IR (infrared) type oven. The drying and baking steps after the application of the liquid crystal alignment agent of the present invention can be performed at any temperature and time, and may be performed multiple times. The baking temperature can be, for example, 40 to 150°C. From the viewpoint of shortening the process, it may be performed at 40 to 120°C. The baking time is not particularly limited, but may be 1 to 10 minutes or 1 to 5 minutes. When the amic acid or amic acid ester in the polymer is thermally imidized, a baking step can be performed after the baking step, for example, at a temperature range of 190 to 250°C or 200 to 240°C. The baking time is not particularly limited, but may be 5 to 40 minutes or 5 to 30 minutes.

[0121] <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. In order to improve the liquid crystal alignment, the substrate on which the liquid crystal alignment film is coated 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 preferable, and 100 to 5,000 mJ / cm 2 The liquid crystal alignment film thus prepared can stably align liquid crystal molecules in a certain direction.

[0122] 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 the linearly polarized UV light is preferably 10:1 or more, and more preferably 20:1 or more.

[0123] <Process (4)> Step (4) is a step of baking the film obtained in step (3) at 100° C. or higher and at a temperature higher than that in step (2). The baking temperature is not particularly limited as long as it is 100° C. or higher and higher than the baking 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 baking time is preferably 5 to 120 minutes, more preferably 5 to 60 minutes, and even more preferably 5 to 30 minutes.

[0124] 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.

[0125] Furthermore, after carrying out either the step (3) or (4), the obtained liquid crystal alignment film can be subjected to a contact treatment using water or a solvent.

[0126] The solvent used in the contact treatment is not particularly limited as long as it dissolves the decomposition product generated from the liquid crystal alignment film by 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 them, water, 2-propanol, 1-methoxy-2-propanol, and ethyl lactate are preferred from the viewpoint of versatility and solvent safety. Water, 1-methoxy-2-propanol, and ethyl lactate are more preferred. The solvent may be one type or a combination of two or more types.

[0127] The contact treatment, i.e., the treatment of the liquid crystal alignment film irradiated with polarized ultraviolet light with water or a solvent, includes 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 the decomposition products generated from the liquid crystal alignment film by ultraviolet light. In particular, immersion treatment for 1 to 30 minutes is preferable. The solvent during the contact treatment may be at room temperature or heated, preferably 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.

[0128] After the contact treatment, it is preferable to rinse the film with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone, or methyl ethyl ketone, or to bake the liquid crystal alignment film. In this case, either the rinsing or the baking may be performed, or both may be performed. The baking temperature is preferably 150 to 300°C. Of these, 180 to 250°C is preferable, and 200 to 230°C is more preferable. The baking time is preferably 10 seconds to 30 minutes, and more preferably 1 to 10 minutes.

[0129] The liquid crystal alignment film of the present invention is suitable as a liquid crystal alignment film for a horizontal electric field type liquid crystal display element such as an IPS type or an FFS type, and is particularly useful as a liquid crystal alignment film for a FFS type liquid crystal display element. The liquid crystal display element is obtained by preparing a liquid crystal cell by a known method after obtaining a substrate with a liquid crystal alignment film obtained from the liquid crystal alignment agent of the present invention, and using the liquid crystal cell.

[0130] As an example of a method for fabricating a liquid crystal cell, a liquid crystal display element having a passive matrix structure will be described below. However, a liquid crystal display element having an active matrix structure 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.

[0131] Specifically, transparent glass substrates are prepared, and a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes may be, for example, ITO electrodes, and are patterned to display a desired image. Next, an insulating film is provided on each substrate so as to cover the common electrode and the segment electrode. The insulating film may be, for example, a SiO2-TiO2 film formed by the sol-gel method.

[0132] Next, a liquid crystal alignment film is formed on each substrate, and one substrate is superimposed on the other substrate so that the liquid crystal alignment film faces each other, and the periphery is bonded with a sealant. In order to control the gap between the substrates, a spacer is usually mixed into the sealant, and it is also preferable to scatter spacers for controlling the gap between the substrates on the inner surface where the sealant is not provided. An opening is provided in a part of the sealant so that liquid crystal can be filled from the outside. Next, a liquid crystal material is injected into the space surrounded by the two substrates and the sealant through the opening provided in the sealant, and then the opening is sealed with an adhesive. For the injection, a vacuum injection method or a method utilizing capillary action in the atmosphere may be used. The liquid crystal material may be either a positive type liquid crystal material or a negative type liquid crystal material. Next, a polarizing plate is installed. Specifically, a pair of polarizing plates is attached to the surface of the two substrates opposite to the liquid crystal layer.

[0133] By using the manufacturing method of the present invention, it is possible to suppress image retention caused by long-term AC driving in liquid crystal display elements of IPS driving type or FFS driving type. In addition, by carrying out step (3) after baking at a temperature range of 40 to 150°C in step (2), a liquid crystal alignment film can be obtained with fewer steps than in the past. The liquid crystal aligning agent of the present invention can be particularly preferably used in a manufacturing method of a liquid crystal alignment film including a step of carrying out step (3) after baking at a temperature range of 40 to 150°C in step (2). EXAMPLES

[0134] (solvent) NMP: N-methyl-2-pyrrolidone BCS: Butyl cellosolve (Diamine) DA-1 to DA-9: Compounds represented by the following formulas (DA-1) to (DA-9), respectively. (Tetracarboxylic acid dianhydride) CA-1 to CA-5: Compounds represented by the following formulae (CA-1) to (CA-5), respectively (Additives) C-1: 2,2'-bis(4-hydroxy-3,5-dihydroxymethylphenyl)propane (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):

[0135] [ka]

[0136] [ka]

[0137] [ka] (Fmoc represents a 9-fluorenylmethyloxycarbonyl group.)

[0138] <Viscosity measurement> Measurements were performed using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL, a cone rotor TE-1 (1°34', R24), and a temperature of 25°C.

[0139] <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.)), deuterated dimethyl sulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) (0.53 mL) was added, and the mixture was completely dissolved by ultrasonication. 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 peak integrated value of this proton and the proton peak integrated value of the proton peak 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%).

[0140] [Polymer synthesis example] <Synthesis Example 1> 4.95g (20.3mmol) of DA-1, 5.30g (18.0mmol) of DA-2, and 1.60g (6.75mmol) of DA-3 were weighed out into a 200mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and NMP was added to the mixture so that the concentration was 12% by mass. The mixture was stirred and dissolved while feeding nitrogen. 9.28g (41.4mmol) of CA-1 was added while stirring this diamine solution, and NMP was added to the mixture so that the concentration was 12% by mass. The mixture was stirred at 40°C for 24 hours to obtain a polyamic acid solution. 35 g (8.9 mmol) of the obtained polyamic acid solution was taken in a 100 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, 11.7 g of NMP was added, and the mixture was stirred for 30 minutes. 2.74 g of acetic anhydride (3 equivalents relative to the molar amount of polyamic acid) and 0.71 g of pyridine (equivalent to the molar amount of polyamic acid) were added to the obtained polyamic acid solution, and the mixture was heated at 50 ° C for 3 hours to perform chemical imidization. The obtained reaction solution was poured into 150 mL of methanol while stirring, the precipitate was filtered off, and the resin powder was washed by performing the same operation twice, and then dried at 60 ° C for 12 hours to obtain a polyimide resin powder. The imidization rate of this polyimide resin powder was 75%. 3.60 g of the obtained polyimide resin powder was taken in a 100 mL Erlenmeyer flask, NMP was added so that the solid concentration was 12%, and the mixture was stirred and dissolved at 70 ° C for 24 hours to obtain a polyimide solution (PI-1).

[0141] <Synthesis Examples 2 to 10> Polyimide solutions (PI-2) to (PI-10) 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 relative to 100 parts by mole of the total amount of tetracarboxylic acid derivatives used in the synthesis for the tetracarboxylic acid component, and the blending ratio (parts by mole) of each compound relative to 100 parts by mole of the total amount of diamines used in the synthesis for the diamine component. The organic solvents 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 the preparation of the polyimide solution. <Synthesis Example 11> 3.37g (8.0mmol) of DA-7, 2.39g (8.0mmol) of DA-8, and 4.78g (24.0mmol) of DA-9 were weighed out into a 200mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and NMP was added to the mixture so that the concentration was 12% by mass. The mixture was stirred and dissolved while feeding nitrogen. 11.3g (38.5mmol) of CA-5 was added while stirring this diamine solution, and NMP was added to the mixture so that the concentration was 12% by mass. The mixture was stirred at 70°C for 24 hours to obtain a polyamic acid solution (PAA-1).

[0142] [Table 1]

[0143] [Preparation of liquid crystal alignment agent] <Comparative Example 1> The polyimide solution (PI-1) obtained in Synthesis Example 1, NMP, and BCS were added to a sample tube containing a stirrer, and S-1, C-1, and F-1 were added in amounts of 1 part by mass, 10 parts by mass, and 15 parts by mass, respectively, per 100 parts by mass of polymer solid content, and the mixture was stirred for 30 minutes. After stirring, a liquid crystal alignment agent (R1) was obtained in which the solid content concentration of the polyimide solution (PI-1) was 6% by mass and the solvent composition was NMP:BCS=80:20 by mass ratio.

[0144] <Comparative Examples 2 to 5, Examples 1 to 12> Liquid crystal alignment agents (R2) to (R5) and (1) to (12) 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 indicate 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 the preparation of the liquid crystal alignment agent, for the polymers and additives, respectively. For the 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 the organic solvents in the liquid crystal alignment agent.

[0145] [Table 2]

[0146] Using the liquid crystal alignment agent obtained as described above, an FFS drive liquid crystal cell was produced according to the procedure described below, and its characteristics were evaluated.

[0147] [FFS drive liquid crystal cell configuration] The liquid crystal cell for Fringe Field Switching (FFS) mode is a set of a first glass substrate on which an FOP (Finger on Plate) electrode layer consisting of a planar common electrode, an insulating layer, and a comb-shaped pixel electrode is formed on the surface, and a second glass substrate on which a columnar spacer with a height of 3.5 μm is formed on the surface and an ITO film for antistatic is formed on the back surface. The pixel electrode has a comb shape in which multiple electrode elements with a width of 3 μm and bent at an internal angle of 160° at the center are arranged in parallel with a 6 μm gap, and one pixel has a first region and a second region with a line connecting the bent parts of the multiple electrode elements as the boundary. 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.

[0148] [Preparation of liquid crystal cells] A liquid crystal alignment agent filtered through a filter with a pore size of 1.0 μm was applied to the surface of each of the above-mentioned pair of glass substrates by spin coating, and then dried on a hot plate at 80° C. for 2 minutes. After that, linearly polarized ultraviolet light with a wavelength of 254 nm and an extinction ratio of 26:1 was applied to the coating surface through a polarizing plate at a rate of 150 to 350 mJ / cm. 2 The substrate was then irradiated and then 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 liquid crystal alignment film, and the other substrate was attached so that the liquid crystal alignment film surface faced each other, and the sealant (Mitsui Chemicals, Inc., XN-1500T) was cured to prepare an empty cell. Liquid crystal (Merck, Inc., MLC-3019) was vacuum-injected into this empty cell at room temperature by a reduced pressure injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal cell. The obtained liquid crystal cell was then heated at 120°C for 1 hour (hereinafter, this treatment is also referred to as ISO treatment), and left overnight before being used for each evaluation.

[0149] <Evaluation of liquid crystal alignment> Using liquid crystal cells before the ISO treatment, the evaluation was performed by defining those with initial flow alignment as "bad" and those without as "good". <Evaluation of in-plane uniformity of contrast> The twist angle of the liquid crystal display element was evaluated using OPTIPRO-micro manufactured by Shintech Co., Ltd. The fabricated liquid crystal cell was placed on the measurement stage, and 20 points within the first pixel plane were measured without applying voltage, 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."

[0150] <Voltage holding ratio evaluation> A voltage of 1 V was applied for 60 microseconds to the liquid crystal cell prepared above using a device manufactured by Toyo Corporation, and the voltage retention rate after 1,000 milliseconds was measured at 60°C. In this case, a voltage retention rate of 90% or more was defined as "good", and a voltage retention rate of less than 90% was defined as "poor".

[0151] <Evaluation Results> Table 3 shows the evaluation results of the liquid crystal display elements obtained by using the liquid crystal alignment agents (1) to (12) and (R1) to (R5) obtained in the above Examples 1 to 12 and Comparative Examples 1 to 5.

[0152] [Table 3]

Claims

1. At least one repeating unit (a1) selected from the group consisting of repeating units represented by the following formula (1-a) and repeating units represented by the following formula (1-i), A liquid crystal aligning agent for a photoalignment method, comprising at least one repeating unit (a2) selected from the group consisting of repeating units represented by the following formula (2-a) and repeating units represented by the following formula (2-i), and containing at least one polymer (A) selected from the group consisting of polyimide precursors and imidized polymers thereof, the repeating unit (a1) accounting for 1 to 20 mol % of all repeating units: 【Chemistry 1】 【Chemistry 2】 (In the formula, X １ represents a tetravalent organic group represented by the following formula (B), and X ２ represents a tetravalent organic group represented by the following formula (C). R and Z each independently represent a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. A plurality of R and Z may be the same or different. Y １ , Y ２ each independently represents a divalent organic group represented by the following formula (O): 【Chemistry 3】 (In the formula, R ｂ１ ~R ｂ４ Each of L independently represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 6 carbon atoms. １ is a single bond, -CH ２ -, -(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 -O-C(=O)-. ｃ１ ~R ｃ４ 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; R ｃ１ ~R ｃ４ At least one of represents a group other than a hydrogen atom as defined above.) 【Chemistry 4】 (Ar represents a benzene ring, a biphenyl structure, or a naphthalene ring, and two Ar may be the same or different, and any hydrogen atom in the ring may be replaced with a monovalent organic group. Q ２ Ha-CH ２ -, -(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 - is replaced with any of -O-, -C(=O)-, or -O-C(=O)-. p is an integer of 1, and at least one of the two Ar's represents a naphthalene ring. * represents a bond.

2. The liquid crystal aligning agent for photoalignment method according to claim 1, wherein the tetravalent organic group represented by the formula (B) is a tetravalent organic group represented by the following formulas (b-1) to (b-2): 【Chemistry 5】 (* represents a bond.)

3. The divalent organic group represented by the formula (O) is a divalent organic group represented by the following formulas (o-1) to (o-6). 【Chemistry 6】

4. The polymer (A) has at least one repeating unit (a3) ​​selected from the group consisting of a repeating unit represented by the following formula (3-a) and a repeating unit represented by the following formula (3-i): The liquid crystal aligning agent for photoalignment method according to any one of claims 1 to 3. 【Chemistry 7】 (In the formula, X ３ represents a tetravalent organic group; Y ３ represents a divalent organic group represented by the following formula (3d). R and Z are the same as those in the formula (1-a). 【Chemistry 8】 (Ar ３ represents a benzene ring or a biphenyl structure, two Ar's may be the same or different, and any hydrogen atom on the ring may be replaced with a monovalent organic group. ３ 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 -O-C(=O)-. * represents a bond.

5. The polymer (A) has at least one repeating unit (a4) selected from the group consisting of a repeating unit represented by the following formula (4-a) and a repeating unit represented by the following formula (4-i): The liquid crystal aligning agent for photoalignment method according to any one of claims 1 to 4. 【Chemistry 9】 (In the formula, R and Z are the same as those in the formula (1-a). X ４ represents a tetravalent organic group; Y ４ 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.

6. The Y ４ The liquid crystal aligning agent for photoalignment method according to claim 5, wherein is a structure represented by the following formulas (Y4-1) to (Y4-4). 【Chemistry 10】 (Boc represents a tert-butoxycarbonyl group.)

7. A liquid crystal alignment film obtained from the liquid crystal alignment agent for photoalignment according to any one of claims 1 to 6.

8. A liquid crystal display device comprising the liquid crystal alignment film according to claim 7.

9. A method for producing a liquid crystal alignment film, comprising the following steps (1) to (3): Step (1): A step of applying the liquid crystal aligning agent for photoalignment method according to any one of claims 1 to 6 onto a substrate. Step (2): A step of heating the applied liquid crystal alignment agent for photoalignment method to obtain a film. Step (3): A step of irradiating the film obtained in step (2) with polarized ultraviolet light.

10. The method for producing a liquid crystal alignment film according to claim 9, further comprising the following step (4): Step (4): A step of baking the film obtained in step (3) at a temperature of 100° C. or higher and higher than that in step (2).

11. The method for producing a liquid crystal alignment film according to claim 9 or 10, wherein the step (2) is a step of obtaining a film by heating at a temperature in the range of 40 to 180° C.

12. 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 9 to 11.

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