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

Abstract

A liquid crystal alignment agent for a photo-alignment method, comprising at least one polymer (A) selected from the group consisting of a polyimide precursor and an imidized polymer of the polyimide precursor, wherein the polymer (A) has: at least one repeating unit (a1) selected from the group consisting of a repeating unit represented by the following formula (1-a) and a repeating unit represented by the following formula (1-i); and at least one repeating unit (a2) selected from the group consisting of a repeating unit represented by the following formula (2-a) and a repeating unit represented by the following formula (2-i), wherein the polymer (A) contains 1 to 20 mol % of the repeating unit (a1) based on all the repeating units.

Description

Technical Field

[0001] The present invention relates to a liquid crystal alignment agent for a photo-alignment method, a liquid crystal alignment film and a liquid crystal display element. Background Art

[0002] In the past, liquid crystal display devices were widely used as display units for personal computers, smart phones, mobile phones, television receivers, etc. Liquid crystal display devices include, for example: a liquid crystal layer sandwiched between an element substrate and a color filter substrate; pixel electrodes and common electrodes for applying an electric field to the liquid crystal layer; an orientation film for controlling the orientation of liquid crystal molecules in the liquid crystal layer; and a thin film transistor (TFT) for switching the electrical signal supplied to the pixel electrode; etc. As a driving method for liquid crystal molecules, known are longitudinal electric field methods such as TN (Twisted Nematic) method and VA (Vertical Alignment) method; and transverse electric field methods such as IPS (In Plane Switching) method and FFS (Fringe Field Switching) method.

[0003] At present, the most popular liquid crystal alignment film in industry is made by performing a so-called rubbing treatment, which is to use cotton, nylon, polyester and other cloth to unidirectionally rub the surface of the film formed on the electrode substrate and formed by polyamic acid and / or the polyimide formed by imidizing the polyamic acid. The rubbing treatment is a simple and productive industrially useful method. However, with the high performance, high precision and large-scale of liquid crystal display elements, there are various problems such as damage to the surface of the alignment film generated in the rubbing treatment, dust, the influence of mechanical force and static electricity, and then the unevenness in the alignment treatment surface. As an orientation treatment method to replace the rubbing treatment, it is known to impart liquid crystal orientation ability by irradiating polarized radiation. As far as the light orientation method is concerned, a method using photoisomerization reaction; a method using photocrosslinking reaction; a method using photodecomposition reaction, etc. (refer to non-patent document 1, patent document 1) are proposed.

[0004] The liquid crystal alignment film as a component of a liquid crystal display element is a film for uniformly aligning liquid crystals, and liquid crystal orientation is one of its important characteristics. However, the liquid crystal alignment film obtained by the photo-alignment method tends to have lower liquid crystal orientation than the liquid crystal alignment film obtained by the conventional rubbing treatment, and the application range of the liquid crystal display device having the liquid crystal alignment film is limited.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 9-297313

[0008] Non-patent literature

[0009] Non-patent document 1: "Functional Materials", November 1997, Vol. 17, No. 11, pp. 13-22 Summary of the invention

[0010] Problems to be solved by the invention

[0011] In actual liquid crystal display elements, the twist angle of liquid crystal in the liquid crystal display element plane is slightly uneven due to manufacturing variations, and the brightness of black display in the liquid crystal display element is uneven in the plane due to such in-plane variations.

[0012] The present invention has been made in view of the above circumstances, and one of its objects is to provide a liquid crystal aligning agent for a photo-alignment method, which can obtain a liquid crystal display element having high liquid crystal alignment by a photo-alignment method, suppressing brightness unevenness within a plane during black display, and improving contrast.

[0013] Solutions for solving problems

[0014] The present inventors have conducted intensive studies and have found that the above-mentioned problems can be solved by using a liquid crystal aligning agent containing specific components, thereby completing the present invention. Specifically, the following contents are the main points.

[0015] A liquid crystal alignment agent for a photo-alignment method, characterized in that it contains at least one polymer (A) selected from the group consisting of a polyimide precursor and an imidized polymer of the polyimide precursor, wherein the polymer (A) has: at least one repeating unit (a1) selected from the group consisting of a repeating unit represented by the following formula (1-a) and a repeating unit represented by the following formula (1-i); and at least one repeating unit (a2) selected from the group consisting of a repeating unit represented by the following formula (2-a) and a repeating unit represented by the following formula (2-i), and the polymer (A) contains 1 to 20 mol % of the repeating unit (a1) based on all the repeating units.

[0016]

[0017] (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 each may be the same or different. Y1 and Y2 each independently represent a divalent organic group represented by the following formula (O).)

[0018]

[0019] (Where 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-, or -(CH2) n -(n is an integer of 2 to 18), or -(CH2) n A group in which at least a part of -CH2- in - is substituted by any of -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 and containing a fluorine atom, or a phenyl group, c1 ~R c4 At least one of them represents a group other than a hydrogen atom in the above definition.)

[0020]

[0021] (Ar represents a benzene ring, a biphenyl structure or a naphthalene ring, two Ars are optionally the same or different, and any hydrogen atom on the ring is optionally substituted by a monovalent organic group. Q2 represents -CH2-, -(CH2) n -(n is an integer of 2 to 18), or -(CH2) n A group in which at least a part of -CH2- of - is substituted by any of -O-, -C(=O)- or -O-C(=O)-. p is an integer of 0 or 1. When p is 0, Ar represents a biphenyl structure, and when p is 1, at least one of the two Ars represents a naphthalene ring. * represents a bonding bond. )

[0022] It should be noted that in this specification, * represents a bond in any case. 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 and 9-fluorenylmethoxycarbonyl.

[0023] Effects of the Invention

[0024] The liquid crystal alignment agent for the photo-alignment method of the present invention contains at least one polymer (A) selected from the group consisting of a polyimide precursor and an imidized polymer of the polyimide precursor, wherein the polymer (A) has the above-mentioned repeating unit (a1) and the above-mentioned repeating unit (a2), and the polymer (A) contains 1 to 20 mol % of the repeating unit (a1) based on all the repeating units, thereby achieving the following effect: a liquid crystal display element with suppressed brightness unevenness within the plane during black display and improved contrast can be obtained by the photo-alignment method. DETAILED DESCRIPTION

[0025] The liquid crystal aligning agent for photo-alignment methods of the present invention (hereinafter, also simply referred to as a liquid crystal aligning agent) will be described.

[0026] <Polymer (A)>

[0027] The liquid crystal aligning agent of the present invention contains at least one polymer (A) selected from the group consisting of a polyimide precursor and an imidized polymer of the polyimide precursor, wherein the polymer (A) has: at least one repeating unit (a1) selected from the group consisting of a repeating unit represented by the following formula (1-a) and a repeating unit represented by the following formula (1-i); and at least one repeating unit (a2) selected from the group consisting of a repeating unit represented by the following formula (2-a) and a repeating unit represented by the following formula (2-i), wherein the polymer (A) contains 1 to 20 mol% of the repeating unit (a1) of all repeating units. It should be noted that the polymer (A) may also be composed of one or more than two kinds.

[0028] <Repeating unit (a1)>

[0029] The repeating unit (a1) of the present invention is at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (1-a) and a repeating unit represented by the following formula (1-i).

[0030]

[0031] (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. The two R and Z may be the same or different. Y1 represents a divalent organic group represented by the following formula (O).)

[0032]

[0033] (Where 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-, or -(CH2) n -(n is an integer of 2 to 18), or -(CH2) n A group in which at least a part of -CH2- in - is substituted by any of -O-, -C(=O)- or -O-C(=O)-.)

[0034]

[0035] (Ar represents a benzene ring, a biphenyl structure, or a naphthalene ring, two Ars are optionally the same or different, and any hydrogen atom on the ring is optionally substituted by a monovalent organic group. Q2 represents -CH2-, -(CH2) n -(n is an integer of 2 to 18), or -(CH2) n A group in which at least a part of -CH2- in - is substituted by any of -O-, -C(=O)- or -O-C(=O)-. p is an integer of 0 or 1. When p is 0, Ar represents a biphenyl structure, and when p is 1, at least one of the two Ars represents a naphthalene ring.

[0036] From the viewpoint of efficiently obtaining the effects of the present invention, preferred examples of L1 are a single bond, -CH2- or -(CH2) n -(n is an integer from 2 to 18).

[0037] From the viewpoint of efficiently obtaining the effects of the present invention, the R b1 ~R b4 A preferred example of is a hydrogen atom.

[0038] From the viewpoint of improving the liquid crystal orientation, the tetravalent organic group represented by the formula (B) is preferably a tetravalent organic group represented by the following formulae (b-1) to (b-2).

[0039]

[0040] From the viewpoint of efficiently obtaining the effects of the present invention, preferred examples of the divalent organic group represented by the formula (O) are divalent organic groups represented by the following formulae (o-1) to (o-7).

[0041]

[0042] <Repeating unit (a2)>

[0043] The repeating unit (a2) of the present invention is at least one repeating unit selected from the group consisting of a repeating unit represented by the following formula (2-a) and a repeating unit represented by the following formula (2-i).

[0044]

[0045] (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. The two R and Z may be the same or different. Y2, including preferred specific examples, has the same meaning as Y1 above.)

[0046]

[0047] (Where Rc1 ~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 and containing a fluorine atom, or a phenyl group, c1 ~R c4 At least one of them represents a group other than a hydrogen atom in the above definition.)

[0048] Examples of the tetravalent organic group represented by the formula (C) include tetravalent organic groups represented by the following formulae (Xc-1) to (Xc-6). Among them, (Xc-1) is preferred from the viewpoint of improving the liquid crystal orientation.

[0049]

[0050] <Repeating unit (a3)>

[0051] The polymer (A) may also be at least one selected from the group consisting of a polyimide precursor and an imidized polymer of the polyimide precursor, and the polymer (A) has, in addition to 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).

[0052]

[0053] (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 have the same meanings as in the above formula (1-a).)

[0054] *-Ar3-Q3-Ar3-* (3d)

[0055] (Ar3 represents a benzene ring or a biphenyl structure, two Ar3s are optionally the same or different, and any hydrogen atom on the above ring is optionally substituted by a monovalent organic group. Q3 represents -(CH2) n -(n is an integer of 2 to 18), or -(CH2) n A group in which at least a part of -CH2- in - is substituted by any of -O-, -C(=O)- or -O-C(=O)-.)

[0056] Examples of the divalent organic group represented by the formula (3d) include divalent organic groups represented by the following formulae (3d-1) to (3d-8), but are not limited thereto.

[0057]

[0058] The polymer (A) may also be at least one selected from the group consisting of a polyimide precursor and an imidized polymer of the polyimide precursor, and the polymer (A) has, in addition to repeating units (a1) and (a2), at least one 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).

[0059]

[0060] (In the formula, R and Z have the same meanings as in the above 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-based protective group)" in the molecule.)

[0061] 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).

[0062]

[0063] In the formula, Q5 is a single bond, -(CH2) n -(n is an integer from 1 to 20), or -(CH2) n Any -CH2- in - is replaced by -O-, -COO-, -OCO-, -NQ9-, -NQ9-CO-, -CO-NQ9-, -NQ9-CO-NQ 10 -, -NQ9-COO- or -O-COO- substituted groups, Q9 and Q 10 Each independently represents a hydrogen atom or a monovalent organic group; Q6 and Q7 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. At least one of Q5, Q6, and Q7 has a carbamate-based protecting group in the group. 10 Specific examples of the monovalent organic group in 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 containing a fluorine atom, the above-mentioned carbamate-based protecting group, and an alkoxyalkyl group having 1 to 6 carbon atoms.

[0064] Here, Y4 may include, for example, structures represented by the following formulae (Y4-1) to (Y4-4), but is not limited thereto.

[0065]

[0066] The polymer (A) may also be at least one selected from the group consisting of a polyimide precursor and an imidized polymer of the polyimide precursor, and the polymer (A) has, in addition to repeating units (a1) and (a2), at least one 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).

[0067]

[0068] In formula (5-a) and formula (5-i), R and Z have the same meanings as those in formula (1-a). X5 represents a tetravalent organic group, and Y5 represents a divalent organic group. Y5 represents a structure other than the divalent organic group represented by formula (3d) or a divalent organic group having 6 to 30 carbon atoms and having a group "-N(D)- (D represents a carbamate-based protective group)" in the molecule. When X5 is synonymous with 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).

[0069] In formula (5-a) and formula (5-i), specific examples of Y5 include divalent organic groups obtained by removing two amino groups from aromatic diamines, and divalent organic groups exemplified in Y6 described later. The aromatic diamines are 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, 3,3'-dimethyl-4,4'-diaminobiphenyl, 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, 3,4'-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, 1,4-bis(4-aminobenzyl)benzene, etc.

[0070] The structures of the tetravalent organic groups of X3, X4 and X5 are not particularly limited, and any structure can be independently selected. Preferred specific examples include the following formulae (X1-1) to (X1-44).

[0071]

[0072]

[0073] In formulas (X1-1) to (X1-4), R 3 ~R 23 Each of them is 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 Preferred is a hydrogen atom, a halogen atom, a methyl group or an ethyl group, and more preferred is a hydrogen atom or a methyl group.

[0074] Specific examples of the formula (X1-1) include the following formulas (X1-1-1) to (X1-1-6). From the viewpoint of liquid crystal orientation and light reaction sensitivity, (X1-1-1) to (X1-1-2) are more preferred, and (X1-1-2) is particularly preferred.

[0075]

[0076] From the viewpoint of obtaining the effects of the present invention well, the polymer (A) preferably contains 1 to 20 mol %, more preferably 1 to 15 mol % of the repeating unit (a1) based on all the repeating units.

[0077] From the viewpoint of obtaining the effects of the present invention well, the total amount of the repeating units (a1) and the repeating units (a2) in the polymer (A) is preferably 5 mol% or more, more preferably 10 mol% or more, of all the repeating units.

[0078] From the viewpoint of obtaining the effect of the present invention well, polymer (A) preferably comprises 1 to 95 mol %, more preferably 1 to 90 mol %, and further preferably 5 to 90 mol % of repeating units (a3) ​​of all repeating units. In this case, the total amount of repeating units (a1) and repeating units (a2) is preferably 99 mol % or less, more preferably 95 mol % or less.

[0079] From the viewpoint of obtaining the effects of the present invention well, the polymer (A) preferably contains 1 to 40 mol %, more preferably 1 to 30 mol %, and even more preferably 1 to 25 mol % of the repeating unit (a4) based on all the repeating units.

[0080] <Polymer (B)>

[0081] From the perspective of reducing the residual image originating from the residual DC, the liquid crystal aligning agent of the present invention may also contain a polymer (B) having a repeating unit represented by the following formula (6). It should be noted that the polymer (B) does not have the above-mentioned repeating unit (a1) and repeating unit (a2) in the same molecule. In addition, the polymer (B) may be composed of one or more than two kinds, and the repeating units constituting the polymer (B) may also be composed of one or more than two kinds.

[0082]

[0083] (X6 is a tetravalent organic group, Y6 is a divalent organic group. R and Z have the same meanings as in formula (1-a).)

[0084] Examples of the tetravalent organic group in the formula X6 include a tetravalent organic group derived from acyclic aliphatic tetracarboxylic dianhydride, a tetravalent organic group derived from alicyclic tetracarboxylic dianhydride, a tetravalent organic group derived from aromatic tetracarboxylic dianhydride, etc. Specific examples of the tetravalent organic group derived from acyclic aliphatic tetracarboxylic dianhydride and the tetravalent organic group derived from alicyclic tetracarboxylic dianhydride include structures selected from the following formulas (x-1) to (x-13).

[0085]

[0086] (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 having a fluorine atom, or a phenyl group. 5 and R 6 Each independently represents a hydrogen atom or a methyl group. )

[0087] Among the above formula (x-1), a structure selected from the group consisting of the following formulae (x1-1) to (x1-6) is preferred.

[0088]

[0089] In the above formulae (x1-1) to (x1-6), *1 represents a bond to one of the acid anhydride groups, and *2 represents a bond to the other of the acid anhydride groups.

[0090] Aromatic tetracarboxylic dianhydride refers to an acid dianhydride obtained by intramolecular dehydration of a carboxyl group bonded to an aromatic ring such as a benzene ring or a naphthalene ring. Specific examples include tetravalent organic groups represented by the above formulae (X1-28) to (X1-40).

[0091] Examples of the divalent organic group in the formula Y6 include a divalent organic group obtained by removing two amino groups from the following diamine, a group represented by any of the formulas (Y-1) to (Y-167) described in International Publication No. 2018 / 117239, and the like, wherein the diamine is: a diamine having a nitrogen-containing heterocyclic ring, at least one nitrogen-containing atom structure (hereinafter also referred to as a nitrogen-containing atom structure) selected from the group consisting of 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, diamine compounds represented by the following formula (3b-1) to (3b-4) and the like having a carboxyl group; 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 4,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzamide, 4,4'-diamino diamines having urea bonds, such as 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indane-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indane-6-amine, and 1,3-bis(4-aminophenethyl)urea; diamines having photopolymerizable groups at the ends, such as 2-(2,4-diaminophenoxy)ethyl methacrylate and 2,4-diamino-N,N-diallylaniline; cholesteryloxy-3,5-diaminobenzene, cholesteryloxy-3,5- Diamines having a steroidal skeleton such as diaminobenzene, cholesteryloxy-2,4-diaminobenzene, 3,5-diaminobenzoic acid cholesteryl ester, 3,5-diaminobenzoic acid cholesteryl ester, 3,5-diaminobenzoic acid lanostanyl ester, 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), etc.

[0092]

[0093] (In formula (3b-1), A 1represents a single bond, -CH2-, -C2H4-, -C(CH3)2-, -CF2-, -C(CF3)2-, -O-, -CO-, -NH-, -N(CH3)-, -CONH-, -NHCO-, -CH2O-, -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. 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-, -CH2O-, -OCH2-, -COO-, -OCO-, -CON(CH3)- or -N(CH3)CO-, and m6 represents an integer of 1 to 4.)

[0094]

[0095] (X v1 ~X v4 , X p1 ~X p2 Each independently represents -(CH2) a -(a is an integer of 1 to 15), -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -CH2O-, -CH2OCO-, -COO-, or -OCO-, X v5 Represents -O-, -CH2O-, -CH2OCO-, -COO-, or -OCO-. X a Represents a single bond, -O-, -NH-, -O-(CH2) m -O-(m represents an integer from 1 to 6), R v1 ~R v4 , R 1a ~R 1b Each independently represents an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkoxyalkyl group having 2 to 20 carbon atoms. V7 ~X V8 Each independently represents -O-, -CH2O-, -COO- or -OCO-. )

[0096]

[0097] Examples of the nitrogen atom-containing heterocyclic ring include pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, pyridazine, pyrazine, indole, benzimidazole, purine, quinoline, isoquinoline, naphthyridine, quinoxaline, phthalazine, triazine, carbazole, acridine, piperidine, piperazine, pyrrolidine, and hexamethyleneimine. Among them, pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole, or acridine is preferred.

[0098] The secondary amino group and the tertiary amino group which the diamine having a nitrogen atom-containing structure may have are represented by, for example, the following formula (n).

[0099]

[0100] 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 to the hydrocarbon group.

[0101] Examples of the monovalent hydrocarbon group of the formula R include alkyl groups such as methyl, ethyl, and propyl; cycloalkyl groups such as cyclohexyl; and aryl groups such as phenyl and tolyl. R is preferably a hydrogen atom or a methyl group.

[0102] Specific examples of the diamine 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 formulas (z-1) to (z-23).

[0103]

[0104]

[0105] From the viewpoint of less afterimages resulting from residual DC, the polymer (B) is preferably a polymer comprising repeating units in which Y6 is a divalent organic group (also collectively referred to as a specific divalent organic group), wherein the divalent organic group is selected from the group consisting of a divalent organic group formed by removing two amino groups from 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, the above-mentioned diamine having a carboxyl group, or the above-mentioned diamine having a urea bond.

[0106] From the viewpoint of reducing afterimages due to residual DC, the polymer (B) may contain 1 mol % or more of all repeating units contained in the polymer (B), and may contain 5 mol % or more of repeating units in which Y6 is the specific divalent organic group.

[0107] From the viewpoint of reducing afterimages caused by residual DC, the content ratio of polymer (A) to polymer (B) may be 10 / 90 to 90 / 10, 20 / 80 to 90 / 10, or 20 / 80 to 80 / 20 in terms of the mass ratio of [polymer (A)] / [polymer (B)].

[0108] <Production method of polyamic acid, polyamic acid ester, and polyimide>

[0109] The polyamic acid ester, the polyamic acid, and the polyimide which are polyimide precursors used in the present invention can be synthesized by a known method described in, for example, International Publication No. 2013 / 157586.

[0110] Specifically, by making a diamine component and a tetracarboxylic acid derivative component carry out (polycondensation) reaction in a solvent to synthesize. As the above-mentioned tetracarboxylic acid derivative component, tetracarboxylic dianhydride or its derivative (tetracarboxylic acid dihalide, tetracarboxylic acid diester or tetracarboxylic acid diester dihalide) can be listed. In the case where a part of polymer (A) or (B) includes an amic acid structure, for example, by making a tetracarboxylic dianhydride component react with a diamine component, a polymer (polyamic acid) with an amic acid structure can be obtained. As a solvent, as long as the generated polymer can be dissolved, it is not particularly limited.

[0111] The diamine component and the tetracarboxylic acid derivative component of the polyimide precursor for obtaining the polymer (A) are selected and used in accordance with the repeating units represented by the above-mentioned formula (1-a), formula (2-a), and the formula (3-a), formula (4-a), and formula (5-a) contained as required in the polymer (A) so as to obtain the structure of the repeating units.

[0112] For example, in the case of a repeating unit represented by the formula (1-a) possessed by the polymer (A), a diamine having a structure of -N(Z)-Y1-N(Z)- (the definitions of Y1 and Z are the same as above) is used as the diamine component, and a tetracarboxylic acid derivative having a structure of the following formula is used as the tetracarboxylic acid derivative component.

[0113]

[0114] (The definition of X1 is the same as above.)

[0115] Polyamic acid esters can be obtained, for example, by the following known methods: [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; [III] a method of reacting a tetracarboxylic acid diester dihalide with a diamine; etc.

[0116] Examples of the method for obtaining a polyimide include thermal imidization in which a solution containing a polyimide precursor such as a polyamic acid or a polyamic acid ester obtained in the above reaction is directly heated; and catalytic imidization in which a catalyst is added to the above solution.

[0117] In the polyimide used in the present invention, the ring closure ratio (also referred to as imidization ratio) of the amic acid group does not necessarily need to be 100%, and can be arbitrarily adjusted according to the application and purpose.

[0118] For example, from the viewpoint of improving the solubility of the polyimide varnish, the imidization ratio of the polyimide may be 20% to 100%, 50% to 99%, or 70% to 99%.

[0119] <Polymer solution viscosity / molecular weight>

[0120] From the viewpoint of workability, it is preferred that the polyamic acid, polyamic acid ester and polyimide used in the present invention have a solution viscosity of, for example, 10 to 1000 mPa·s when they are made into a solution with a concentration of 10 to 15% by mass, but there is no particular limitation. It should be noted that 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 with a concentration of 10 to 15% by mass prepared using a good solvent for the polymer (e.g., γ-butyrolactone, N-methyl-2-pyrrolidone, etc.).

[0121] The weight average molecular weight (Mw) of the polyamic acid, polyamic acid ester and polyimide measured by gel permeation chromatography (GPC) in terms of polystyrene is preferably 1000 to 500000, more preferably 2000 to 300000. In addition, the molecular weight distribution (Mw / Mn) represented by the ratio of Mw to the number average molecular weight (Mn) in terms of polystyrene measured by GPC is preferably 15 or less, more preferably 10 or less. By being in such a molecular weight range, good orientation and stability of the liquid crystal display element can be ensured.

[0122] <Liquid crystal alignment agent>

[0123] The liquid crystal aligning agent of the present invention contains a polymer (A) and a polymer (B) as required. In addition to the polymer (A) and the polymer (B), the liquid crystal aligning agent of the present invention may also contain other polymers. As the types of other polymers, polyesters, polyamides, polyureas, polyorganosiloxanes, cellulose derivatives, polyacetals, polystyrene or its derivatives, poly(styrene-phenylmaleimide) derivatives, poly(meth)acrylates, etc. can be listed.

[0124] The liquid crystal alignment agent is used to make a liquid crystal alignment film, and from the viewpoint of forming a uniform film, it takes the form of a coating liquid. For the liquid crystal alignment agent of the present invention, it is also preferably a coating liquid containing the polymer component and an organic solvent. At this time, the concentration of the polymer in the liquid crystal alignment agent can be appropriately changed according to the setting of the thickness of the coating film to be formed. From the perspective of forming a uniform and defect-free coating film, it is preferably more than 1% by weight, and from the perspective of the storage stability of the solution, it is preferably less than 10% by mass. The concentration of the polymer is particularly preferably 2 to 8% by mass.

[0125] The organic solvent contained in the liquid crystal aligning agent will not be particularly limited as long as the polymer component is uniformly dissolved. 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-dimethylpropionamide, and 3-butoxy-N,N-dimethylpropionamide (these are also collectively referred to as "good solvents"), etc. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide or γ-butyrolactone is preferred. The content of the good solvent is preferably 20 to 99% by mass of the total solvent contained in the liquid crystal aligning agent, more preferably 20 to 90% by mass, and particularly preferably 30 to 80% by mass.

[0126] In addition, the organic solvent contained in the liquid crystal aligning agent is preferably a mixed solvent containing a solvent (also called a poor solvent) that improves the coating property when the liquid crystal aligning agent is applied and the surface smoothness of the coating film in addition to the above-mentioned solvents. Specific examples of the organic solvent used in combination are described below, but are not limited to these.

[0127] 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 monoisopentyl 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, isopentyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone), etc.

[0128] Among them, diisobutylcarbinol, 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.

[0129] Preferred solvent combinations of good solvent and 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; N-methyl -2-pyrrolidone, γ-butyrolactone, 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; N-methyl-2-pyrrolidone, γ-butyrolactone and dipropylene glycol dimethyl ether, etc. The content of the poor solvent is preferably 1 to 80% by mass of the total solvent contained in the liquid crystal alignment agent, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass. The type and content of the poor solvent are appropriately selected according to the coating device, coating conditions, coating environment, etc. of the liquid crystal alignment agent.

[0130] The liquid crystal aligning agent of the present invention may also contain additional components other than the polymer component and the organic solvent (hereinafter, also referred to as additive components). Such additive components include: a close adhesion aid for improving the close adhesion between the liquid crystal aligning film and the substrate, and the close adhesion between the liquid crystal aligning film and the sealant; a compound for improving the strength of the liquid crystal aligning film (hereinafter, also referred to as a cross-linking compound); a compound for promoting imidization; a dielectric for adjusting the dielectric constant and resistance of the liquid crystal aligning film, a conductive substance, etc.

[0131] The cross-linking compound may be a compound having at least one group selected from the group consisting of an oxirane group, an oxetane group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a Michaelis acid structure, a cyclic carbonate group, and a group represented by formula (d), from the viewpoint of exhibiting good resistance to AC residual images and a high improvement in film strength; or a compound among the compounds represented by the following formula (e) (hereinafter, they are collectively referred to as compound (C)).

[0132]

[0133] (R2 and R3 are each independently 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 atoms on the aromatic ring of the above A may be optionally substituted 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 fluorine atoms.)

[0134] Specific examples of compounds having an oxirane group include compounds described in paragraph

[0037] of Japanese Patent Application Laid-Open No. 10-338880, compounds having a triazine ring in the skeleton described in International Publication No. 2017 / 170483, and compounds having two or more oxirane groups. Among them, compounds containing nitrogen atoms such as N,N,N',N'-tetraglycidyl-m-xylene diamine, 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 also be used.

[0135]

[0136] Specific examples of the compound having an oxetanyl group include compounds having two or more oxetanyl groups described in paragraphs

[0170] to

[0175] of International Publication No. 2011 / 132751.

[0137] Specific examples of the compound having a protected isocyanate group include: a compound having two or more protected isocyanate groups described in paragraphs

[0046] to

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

[0119] to

[0120] of International Publication No. 2015 / 141598, and the like. It may also be a compound represented by the following formulas (bi-1) to (bi-3).

[0138]

[0139] Specific examples of the compound having a protected isothiocyanate group include compounds having two or more protected isothiocyanate groups described in JP-A-2016-200798.

[0140] 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.

[0141] Specific examples of the compound having a group containing a Michaelis acid structure include compounds having two or more Michaelis acid structures described in International Publication No. 2012 / 091088.

[0142] Specific examples of the compound having a cyclic carbonate group include compounds described in International Publication No. 2011 / 155577.

[0143] Examples of the alkyl group having 1 to 3 carbon atoms in R2 and R3 of the group represented by the formula (d) include methyl, ethyl, and propyl groups.

[0144] Specific examples of the compound having a group represented by the formula (d) include: International Publication No. 2015 / 072554, the compound having two or more groups represented by the formula (d) described in paragraph

[0058] of Japanese Patent Application Publication No. 2016-118753, the compound described in Japanese Patent Application Publication No. 2016-200798, etc., and the compound may be represented by the following formulas (hd-1) to (hd-8).

[0145]

[0146] 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 in 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 heterocyclic ring. Examples of the aromatic hydrocarbon group include benzene and naphthalene. Examples of the aromatic heterocyclic ring 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 formed by removing one hydrogen atom from the alkylene group, and a divalent or trivalent cyclohexane ring. It should be noted that 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 the formula (e) include compounds described in International Publication No. 2010 / 074269 and compounds represented by the following formulas (e-1) to (e-10).

[0147]

[0148] The above compound is an example of a crosslinking compound, but is not limited thereto. For example, components other than the above disclosed on pages 53

[0105] to 55

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

[0149] 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, and more preferably 1 to 15 parts by mass, from the viewpoint of allowing the crosslinking reaction to proceed and expressing good resistance to AC afterimages, based on 100 parts by mass of the polymer component contained in the liquid crystal aligning agent.

[0150] 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, and N-ethyl Oxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 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-aminopropyltriethoxy Silane, N-phenyl-3-aminopropyl trimethoxysilane, N-phenyl-3-aminopropyl triethoxysilane, N-bis(oxyethylene)-3-aminopropyl trimethoxysilane, N-bis(oxyethylene)-3-aminopropyl triethoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl trimethoxysilane, 3-glycidoxypropyl methyl dimethoxysilane, 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl methyl diethoxysilane, 3-epoxy Silane coupling agents such as propoxypropyl triethoxysilane, p-styryl trimethoxysilane, 3-methacryloxypropyl methyl dimethoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl methyl diethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, tris-(trimethoxysilylpropyl) isocyanurate, 3-mercaptopropyl methyl dimethoxysilane, 3-mercaptopropyl trimethoxysilane, and 3-isocyanate propyl triethoxysilane. When using a silane coupling agent, from the viewpoint of exhibiting good resistance to AC residual image, the amount is preferably 0.1 to 30 parts by mass, and more preferably 0.1 to 20 parts by mass, relative to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent.

[0151] As the compound for promoting the above-mentioned imidization, a compound having a basic site (for example, a primary amino group, an aliphatic heterocycle (for example, a pyrrolidine skeleton), an aromatic heterocycle (for example, an imidazole ring, an indole ring), or a guanidine group, etc.) is preferred (except for the above-mentioned cross-linking compound and the adhesion aid); or a compound that generates the above-mentioned basic site when calcined. More preferred are compounds that generate the above-mentioned basic site when calcined. If preferred specific examples are listed, amino acids in which a part or all of the basic sites possessed by amino acids are protected can be listed. Specific examples of the above-mentioned amino acids include glycine, alanine, cysteine, methionine, asparagine, glutamic acid, valine, leucine, phenylalanine, tyrosine, tryptophan, proline, hydroxyproline, arginine, histidine, lysine, and ornithine. If more preferred specific examples of the compound for promoting imidization are listed, N-α-(9-fluorenylmethoxycarbonyl)-N-τ-(tert-butyloxycarbonyl)-L-histidine can be listed.

[0152] <Method for producing liquid crystal alignment film>

[0153] The method for manufacturing a liquid crystal alignment film using the liquid crystal alignment agent of the present invention is characterized in that the following steps are performed in sequence: a step of applying the above-mentioned liquid crystal alignment agent (step (1)); a step of firing the applied liquid crystal alignment agent (step (2)); a step of irradiating the film obtained in step (2) with polarized ultraviolet rays (step (3)); and a step of firing the film obtained in step (3) at a temperature above 100°C and higher than that of step (2) (step (4)).

[0154] <Process (1)>

[0155] As the substrate coated with the liquid crystal alignment agent used in the present invention, there is no particular limitation as long as it is a substrate with high transparency, and a glass substrate, a silicon nitride substrate, an acrylic substrate, a plastic substrate such as a polycarbonate substrate, etc. can be used. At this time, if a substrate having an ITO electrode or the like for driving the liquid crystal is used, it is preferred from the perspective of process simplification. In addition, in a reflective liquid crystal display element, if it is only a single-sided substrate, an opaque object such as a silicon wafer can also be used, and the electrode in this case can also use a material that reflects light such as aluminum.

[0156] The coating method of the liquid crystal aligning agent is not particularly limited, and is generally performed industrially by screen printing, offset printing, flexographic printing, or inkjet method, etc. Other coating methods include dipping, roll coating, slit coating, spin coating, or spray coating, and these can be used according to the purpose.

[0157] <Process (2)>

[0158] Step (2) is a step of firing 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 by a heating unit such as a heating plate, a heat circulation oven, or an IR (infrared) oven; or thermal imidization of the amic acid or amic acid ester in the polymer can be performed. The drying and firing steps after the liquid crystal alignment agent of the present invention is applied can be selected at any temperature and time, and can be performed multiple times. As the firing temperature, for example, it can be performed at 40 to 150°C. From the perspective of shortening the process, it can also be performed at 40 to 120°C. There is no particular limitation on the firing time, and 1 to 10 minutes or 1 to 5 minutes can be cited. When thermal imidization of the amic acid or amic acid ester in the polymer is performed, a firing step can be performed after the above-mentioned firing step, for example, in a temperature range of 190 to 250°C or 200 to 240°C. There is no particular limitation on the firing time, and 5 to 40 minutes or 5 to 30 minutes can be cited.

[0159] <Step (3)>

[0160] Step (3) is a step of irradiating the film obtained in step (2) with polarized ultraviolet rays. The wavelength of the ultraviolet rays is preferably 200 to 400 nm, and ultraviolet rays with a wavelength of 200 to 300 nm are more preferred. In order to improve the liquid crystal orientation, the substrate coated with the liquid crystal orientation film may be heated at 50 to 250° C. while irradiating it with ultraviolet rays. In addition, the irradiation amount of the ultraviolet rays is preferably 1 to 10,000 mJ / cm 2 , more preferably 100 to 5000 mJ / cm 2 The liquid crystal alignment film produced in this way can stably align the liquid crystal molecules in a fixed direction.

[0161] The higher the extinction ratio of the polarized ultraviolet light, the higher the anisotropy can be imparted, which is preferred. Specifically, the extinction ratio of the linearly polarized ultraviolet light is preferably 10:1 or more, and more preferably 20:1 or more.

[0162] <Step (4)>

[0163] Step (4) is a step of firing the film obtained in step (3) at a temperature of 100° C. or higher and 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.

[0164] Since the reliability of a liquid crystal display element may fall when the thickness of the liquid crystal aligning film after baking is too thin, it is preferably 5-300 nm, and more preferably 10-200 nm.

[0165] Furthermore, after performing any of the steps (3) and (4), the obtained liquid crystal alignment film may be subjected to contact treatment using water or a solvent.

[0166] As the solvent used in the above-mentioned contact treatment, there is no particular limitation as long as it is a solvent that dissolves the decomposition product generated by the liquid crystal alignment film due to ultraviolet irradiation. As specific examples, 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 or cyclohexyl acetate can be listed. Among them, from the perspective of versatility and safety of the solvent, water, 2-propanol, 1-methoxy-2-propanol or ethyl lactate are preferred. Water, 1-methoxy-2-propanol or ethyl lactate are more preferred. The solvent can be one or a combination of two or more.

[0167] As the above-mentioned contact treatment, that is, the treatment of the liquid crystal alignment film irradiated with polarized ultraviolet rays using water and solvent, immersion treatment and spray treatment (also called spray treatment) can be listed. From the perspective of efficiently dissolving the decomposition products generated by the liquid crystal alignment film due to ultraviolet rays, the treatment time in these treatments is preferably 10 seconds to 1 hour. Among them, it is preferred to perform an immersion treatment for 1 to 30 minutes. In addition, the solvent during the contact treatment can be at room temperature or heated, preferably 10 to 80°C, and more preferably 20 to 50°C. In addition, from the perspective of the solubility of the decomposition product, ultrasonic treatment, etc. can also be performed as needed.

[0168] After the contact treatment, it is preferred to perform rinsing (also referred to as leaching) with a low boiling point solvent such as water, methanol, ethanol, 2-propanol, acetone or methyl ethyl ketone, and calcining of the liquid crystal alignment film. At this time, either leaching or calcining may be performed, or both may be performed. The calcining temperature is preferably 150 to 300°C. Among them, 180 to 250°C is preferred. 200 to 230°C is more preferred. In addition, the calcining time is preferably 10 seconds to 30 minutes. Among them, 1 to 10 minutes is preferred.

[0169] The liquid crystal alignment film of the present invention is preferably used as a liquid crystal alignment film of a liquid crystal display element of a transverse electric field mode such as an IPS mode and an FFS mode, and is particularly useful as a liquid crystal alignment film of a liquid crystal display element of an FFS mode. 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.

[0170] As an example of a method for manufacturing a liquid crystal cell, a passive matrix liquid crystal display element is described as an example. It should be noted that 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.

[0171] Specifically, a transparent glass substrate is prepared, a common electrode is provided on one substrate, and a segment electrode is provided on the other substrate. These electrodes can be, for example, ITO electrodes, and are patterned in a manner that enables the desired image display. Next, an insulating film is provided on each substrate in a manner that covers the common electrode and the segment electrode. The insulating film can be, for example, a SiO2-TiO2 film formed by a sol-gel method.

[0172] Next, a liquid crystal alignment film is formed on each substrate, and the substrate of one side is superimposed with the substrate of the other side in a manner that the liquid crystal alignment film faces face each other, and the periphery is bonded by a sealant. In order to control the substrate gap, a spacer is usually pre-mixed in the sealant. In addition, it is preferred to pre-spread the spacer for substrate gap control in the surface part where the sealant is not provided. In a part of the sealant, an opening that can be filled with liquid crystal from the outside is pre-set. Next, through the opening provided in the sealant, a liquid crystal material is injected into the space surrounded by the two substrates and the sealant, and then the opening is sealed with an adhesive. The injection can use a vacuum injection method or a method that uses capillary phenomena in the atmosphere. The liquid crystal material can use any of a positive liquid crystal material and a negative liquid crystal material. Next, a polarizer is set. Specifically, a pair of polarizers are bonded to the surface of the two substrates on the opposite side of the liquid crystal layer.

[0173] By using the manufacturing method of the present invention, it is possible to suppress the residual image caused by long-term AC driving in the liquid crystal display element of the IPS driving method and the FFS driving method. In addition, by performing step (3) after calcining in the 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 alignment agent of the present invention can be particularly preferably used in the following method for manufacturing a liquid crystal alignment film, the manufacturing method comprising the step of performing step (3) after calcining in the temperature range of 40 to 150° C. in step (2).

[0174] Example

[0175] (Solvent)

[0176] NMP: N-methyl-2-pyrrolidone.

[0177] BCS: Butyl Cellosolve.

[0178] (Diamine)

[0179] DA-1 to DA-9: compounds represented by the following formula (DA-1) to (DA-9), respectively.

[0180] (Tetracarboxylic dianhydride)

[0181] CA-1 to CA-5: compounds represented by the following formula (CA-1) to (CA-5), respectively.

[0182] (additive)

[0183] C-1: 2,2'-bis(4-hydroxy-3,5-dihydroxymethylphenyl)propane (a compound represented by the following formula (C-1)).

[0184] S-1: A compound represented by the following formula (S-1).

[0185] F-1: A compound represented by the following formula (F-1).

[0186]

[0187] (Fmoc represents 9-fluorenylmethoxycarbonyl.)

[0188] <Viscosity measurement>

[0189] The measurement was performed using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample amount of 1.1 mL, a conical rotor TE-1 (1°34', R24), and a temperature of 25°C.

[0190] <Measurement of Imidization Ratio>

[0191] Add polyimide powder (20 mg) to an NMR sample tube (NMR standard sampling tube, φ5 (manufactured by Kusano Scientific Co., Ltd.)), add deuterated dimethyl sulfoxide (DMSO-d6, 0.05% TMS (tetramethylsilane) mixture) (0.53 mL), and apply ultrasonic waves to completely dissolve it. The solution was measured by 500 MHz proton NMR in an NMR measuring machine (JNW-ECA500) (manufactured by JEOL DATUM Co., Ltd.). The imidization rate was calculated as follows: the proton derived from the structure that does not change before and after imidization is determined as the reference proton, and the peak integral value of the proton derived from the NH group of the amic acid appearing near 9.5 ppm to 10.0 ppm is used to calculate it using the following formula.

[0192] Imidization rate (%) = (1-α·x / y) × 100

[0193] In the above formula, x is the peak integral value of protons derived from NH groups of amic acid, y is the peak integral value of reference protons, and α is the number ratio of reference protons to one proton of NH groups of amic acid in the case of polyamic acid (imidation ratio 0%).

[0194] [Synthesis Example of Polymer]

[0195] <Synthesis example 1>

[0196] 4.95 g (20.3 mmol) of DA-1, 5.30 g (18.0 mmol) of DA-2, and 1.60 g (6.75 mmol) of DA-3 were weighed into a 200 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, and NMP was added so that the concentration became 12% by mass, and stirred to dissolve while nitrogen was supplied. While stirring the diamine solution, 9.28 g (41.4 mmol) of CA-1 was added, and NMP was added so that the concentration became 12% by mass, and stirred at 40° C. for 24 hours to obtain a polyamic acid solution.

[0197] Take 35g (8.9mmol) of the obtained polyamic acid solution in a 100mL four-necked flask with a stirring device and a nitrogen introduction tube, add 11.7g of NMP and stir for 30 minutes. Add 2.74g (3 equivalents in molar ratio with polyamic acid) of acetic anhydride and 0.71g (equivalent in molar ratio with polyamic acid) of pyridine to the obtained polyamic acid solution, heat at 50°C for 3 hours, and carry out chemical imidization. The obtained reaction solution is dropped into 150mL of methanol while stirring, filter the precipitate precipitated, implement twice the same operation thus to clean the resin powder, dry at 60°C for 12 hours, thus obtain polyimide resin powder. The imidization rate of the polyimide resin powder is 75%. 3.60 g of the obtained polyimide resin powder was placed in a 100 mL Erlenmeyer flask, NMP was added so that the solid content concentration became 12%, and the mixture was stirred at 70° C. for 24 hours to dissolve the mixture, thereby obtaining a polyimide solution (PI-1).

[0198] <Synthesis Examples 2 to 10>

[0199] The types and amounts of the monomers used were changed as described in Table 1 below. In addition, polyimide solutions (PI-2) to (PI-10) were obtained by the same method as in Synthesis Example 1. It should be noted that in Table 1, the numerical values ​​in parentheses indicate the mixing ratio (mol parts) of each compound relative to 100 mol parts of the total amount of tetracarboxylic acid derivatives used for synthesis, and the mixing ratio (mol parts) of each compound relative to 100 mol parts of the total amount of diamines used for synthesis for the tetracarboxylic acid component, and the mixing ratio (mol parts) of each compound relative to 100 mol parts of the total amount of diamines used for synthesis for the diamine component. For the organic solvent, the mixing ratio (mass parts) of each organic solvent relative to 100 mass parts of the total amount of organic solvents used for the preparation of the polyimide solution is indicated.

[0200] <Synthesis Example 11>

[0201] 3.37 g (8.0 mmol) of DA-7, 2.39 g (8.0 mmol) of DA-8, and 4.78 g (24.0 mmol) of DA-9 were weighed into a 200 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, and NMP was added so that the concentration became 12% by mass, and stirred while nitrogen was supplied to dissolve. While stirring the diamine solution, 11.3 g (38.5 mmol) of CA-5 was added, and NMP was added so that the concentration became 12% by mass, and stirred at 70° C. for 24 hours to obtain a polyamic acid solution (PAA-1).

[0202] [Table 1]

[0203]

[0204] [Preparation of Liquid Crystal Alignment Agent]

[0205] <Comparative Example 1>

[0206] The polyimide solution (PI-1) obtained in Synthesis Example 1, NMP and BCS were added to a sample tube with a stirrer, and S-1, C-1 and F-1 were added in an amount of 1 part by mass, 10 parts by mass and 15 parts by mass, respectively, relative to 100 parts by mass of the polymer solid content, and stirred for 30 minutes. After stirring, a liquid crystal aligning agent (R1) having a solid content concentration of 6% by mass of the polyimide solution (PI-1) and a solvent composition of NMP:BCS=80:20 by mass ratio was obtained.

[0207] <Comparative Examples 2 to 5, Examples 1 to 12>

[0208] The polymer components used were changed as described in Table 2 below. In addition, liquid crystal aligning agents (R2) to (R5) and (1) to (12) were obtained by the same method as in Comparative Example 1. In Table 2, the values ​​in parentheses indicate the proportion (parts by mass) of each polymer component or additive relative to 100 parts by mass of the total polymer component used to prepare the liquid crystal aligning agent for polymers and additives. For organic solvents, the proportion (parts by mass) of each organic solvent relative to 100 parts by mass of the total amount of organic solvents in the liquid crystal aligning agent is indicated.

[0209] [Table 2]

[0210]

[0211] Using the liquid crystal aligning agent obtained as described above, an FFS drive liquid crystal cell was produced by the procedure shown below, and the characteristics were evaluated.

[0212] [Configuration of FFS drive liquid crystal cell]

[0213] In the case of a liquid crystal box for a fringe field switching (FFS) mode, a first glass substrate and a second glass substrate are set as a set, wherein a FOP (Finger on Plate) electrode layer composed of a common electrode in a planar shape, an insulating layer, and a pixel electrode in a comb-tooth shape is formed on the surface of the first glass substrate, and a columnar spacer with a height of 3.5 μm is formed on the surface of the second glass substrate, and an ITO film for antistatic is formed on the back. The pixel electrode has a comb-tooth shape in which a plurality of electrode elements with a width of 3 μm are arranged in parallel at intervals of 6 μm and bent at an inner angle of 160° in the central part, and a pixel has a first region and a second region with a line connecting the bent portions of the plurality of electrode elements as a boundary.

[0214] It should be noted that the liquid crystal orientation film formed on the first glass substrate is oriented in a manner such that the direction dividing the inner angle of the pixel bending portion into equal parts is orthogonal to the orientation direction of the liquid crystal, and the liquid crystal orientation film formed on the second glass substrate is oriented in a manner such that the orientation direction of the liquid crystal on the first substrate is consistent with the orientation direction of the liquid crystal on the second substrate when manufacturing the liquid crystal box.

[0215] [Production of Liquid Crystal Cell]

[0216] The liquid crystal aligning agent filtered through a filter with a pore size of 1.0 μm was applied to the surface of each of the above-mentioned glass substrates by spin coating, and dried on a hot plate at 80° C. for 2 minutes. 2The substrate was irradiated with ultraviolet light having a wavelength of 254 nm and linearly polarized at an extinction ratio of 26:1 via a polarizer, and then baked in a hot air circulation oven at 230° C. for 30 minutes to obtain two substrates with a liquid crystal alignment film having a film thickness of 100 nm.

[0217] Next, a sealant was printed on one side of the above-mentioned set of substrates with a liquid crystal alignment film, and the other substrate was laminated in a manner such that the liquid crystal alignment film faces each other, and the sealant (XN-1500T manufactured by Mitsui Chemicals) was cured to produce an empty box. Liquid crystal (MLC-3019 manufactured by MERCK) was vacuum injected into the empty box at room temperature by the reduced pressure injection method, and the injection port was sealed to obtain an FFS-driven liquid crystal box. Then, the obtained liquid crystal box was heated at 120°C for 1 hour (hereinafter, this treatment is also referred to as ISO treatment), and left overnight for each evaluation.

[0218] <Evaluation of Liquid Crystal Orientation>

[0219] Evaluation was performed using the liquid crystal cells before the ISO treatment, with the liquid crystal cells having an initial flow orientation defined as "bad" and the liquid crystal cells having no initial flow orientation defined as "good".

[0220] <Evaluation of in-plane uniformity of contrast>

[0221] The twist angle of the liquid crystal display element was evaluated using OPTIPRO-micro manufactured by SHINTECH. The produced liquid crystal box was placed on a measuring table, and 20 points were measured in the first pixel plane without applying voltage, and the standard deviation was calculated. For the evaluation, the case where the standard deviation of the twist angle was 0.5 or more was defined as "poor", and the case where it was less than 0.5 was defined as "good", and the evaluation was performed.

[0222] <Voltage holding ratio evaluation>

[0223] The liquid crystal box produced above was subjected to a voltage of 1V for 60 microseconds at 60°C using an apparatus manufactured by TOYO Corporation, and the voltage holding ratio after 1000 milliseconds was measured. At this time, the case where the voltage holding ratio was maintained at 90% or more was defined as "good", and the case where the voltage holding ratio was less than 90% was defined as "poor", and the evaluation was performed.

[0224] <Evaluation Results>

[0225] Table 3 shows the evaluation results of the liquid crystal display elements obtained using the liquid crystal aligning agents (1) to (12) and (R1) to (R5) obtained in Examples 1 to 12 and Comparative Examples 1 to 5.

[0226] [Table 3]

[0227]

Claims

1. A liquid crystal alignment agent for a photo-alignment method, characterized in that: The invention contains at least one polymer (A) selected from the group consisting of a polyimide precursor and an imidized polymer of the polyimide precursor, wherein the polymer (A) has: At least one repeating unit (a1) selected from the group consisting of a repeating unit represented by the following formula (1-a) and a repeating unit represented by the following formula (1-i); and at least one repeating unit (a2) selected from the group consisting of a repeating unit represented by the following formula (2-a) and a repeating unit represented by the following formula (2-i), wherein the polymer (A) contains 1 to 20 mol % of the repeating unit (a1) based on all the repeating units, In formula (1-a), (1-i), (2-a), and (2-i), 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 Rs and Zs may be the same or different; Y1 and Y2 each independently represent a divalent organic group represented by the following formula (O), In formula (B) and (C), 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 -, or the -(CH2) n -CH2- is substituted by any of -O-, -C(=O)- or -O-C(=O)-, wherein -(CH2) n - where n is an integer from 2 to 18; 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 and containing a fluorine atom, or a phenyl group, c1 ~R c4 At least one of represents a group other than a hydrogen atom as defined above, In formula (O), Ar represents a benzene ring, a biphenyl structure or a naphthalene ring, two Ars are optionally the same or different, and any hydrogen atom on the ring is optionally substituted by a monovalent organic group; Q2 represents -CH2-, -(CH2) n -, or the -(CH2) n -CH2- is substituted by any of -O-, -C(=O)- or -O-C(=O)-, wherein -(CH2) n - wherein n is an integer of 2 to 18; p is an integer of 0 or 1; wherein, when p is 0, Ar represents a biphenyl structure, and when p is 1, at least one of the two Ars represents a naphthalene ring; and * represents a bonding bond.

2. The liquid crystal alignment agent for photo-alignment 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), In the formulae (b-1) and (b-2), * represents a bonding bond.

3. The liquid crystal alignment agent for photo-alignment method according to claim 1 or 2, wherein The divalent organic group represented by the formula (O) is a divalent organic group represented by the following formulas (o-1) to (o-7), 4. The liquid crystal alignment agent for photo-alignment method according to claim 1 or 2, wherein 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). In formula (3-a) and (3-i), X3 represents a tetravalent organic group, Y3 represents a divalent organic group represented by the following formula (3d); R and Z have the same meanings as in the above formula (1-a). *-Ar3-Q3-Ar3-* (3d) In formula (3d), Ar3 represents a benzene ring or a biphenyl structure, two Ars are optionally the same or different, and any hydrogen atom on the ring is optionally replaced by a monovalent organic group; Q3 represents -(CH2) n -, or the -(CH2) n -CH2- is substituted by any of -O-, -C(=O)- or -O-C(=O)-, wherein -(CH2) n - where n is an integer from 2 to 18; * represents a bonding key.

5. The liquid crystal alignment agent for photo-alignment method according to claim 1 or 2, wherein 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). In formula (4-a) and (4-i), R and Z have the same meanings as in formula (1-a); X4 represents a tetravalent organic group, Y4 represents a divalent organic group having 6 to 30 carbon atoms and having a group "-N(D)-" in the molecule, and D in the -N(D)- represents a carbamate-based protecting group.

6. The liquid crystal alignment agent for photo-alignment method according to claim 5, wherein The Y4 is a structure represented by the following formula (Y4-1) to (Y4-4), In the formulae (Y4-1) to (Y4-4), Boc represents a tert-butoxycarbonyl group. 7 . A liquid crystal alignment film obtained from the liquid crystal alignment agent for a photo-alignment method according to claim 1 . 8 . A liquid crystal display element 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 alignment agent for photo-alignment method according to any one of claims 1 to 6 onto a substrate; Step (2): a step of heating the applied photo-alignment liquid crystal alignment agent to obtain a film; Step (3): a step of irradiating the film obtained in step (2) with polarized ultraviolet rays.

10. The method for manufacturing a liquid crystal alignment film according to claim 9, wherein: It also includes the following step (4), Step (4): a step of firing 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 heating the liquid crystal aligning agent for a photo-alignment method within a temperature range of 40 to 180° C. to obtain a film. 12 . A liquid crystal display element comprising a liquid crystal alignment film obtained by the method for producing a liquid crystal alignment film according to claim 9 .

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