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

Abstract

The present invention provides a liquid crystal aligning agent which, while obtaining a liquid crystal alignment film having a pretilt angle of 1 degree or less, also gives a liquid crystal display element with a low incidence of display defects (line burn-in) even when a negative liquid crystal is used as the liquid crystal material. The liquid crystal aligning agent of the present invention contains a polyimide (A) obtained by imidizing a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative component and a diamine component. The tetracarboxylic acid derivative component contains 1,2,3,4-butanetetracarboxylic dianhydride or a derivative thereof, and the diamine component contains at least one or more diamines selected from the following formulas (1a) to (1b) and the diamine shown by the following formula (2). (The meanings of the respective substituents are as described in the specification.)

Description

Technical Field

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

[0002] A liquid crystal display element is configured such that a liquid crystal layer is sandwiched between a pair of transparent substrates each having an electrode. Further, in a liquid crystal display element, an organic film made of an organic material is used as a liquid crystal alignment film in order to make the liquid crystal assume a desired alignment state between the substrates. That is, the liquid crystal alignment film is a constituent member of the liquid crystal display element, is formed on the surface of the substrate sandwiching the liquid crystal and in contact with the liquid crystal, and functions to align the liquid crystal in a certain direction between the substrates. Further, the pretilt angle of the liquid crystal can be controlled by the liquid crystal alignment film. A method of reducing the pretilt angle by selecting the structure of polyimide is known (see Patent Documents 1 and 2).

[0003] In recent years, with the high performance of liquid crystal display elements, in addition to applications such as large-screen and high-definition liquid crystal televisions, liquid crystal display elements are also used in in-vehicle applications such as car navigation systems, instrument panels, surveillance cameras, and monitors for medical cameras. Depending on the requirements of the viewing angle characteristics, a lower pretilt angle than in the past is also required for the rubbed alignment film.

[0004] In particular, a problem has been pointed out regarding the viewing angle dependence of the hue due to the pretilt angle, so-called color shift. To solve this problem, a liquid crystal alignment film having a pretilt angle of 1 degree or less has been proposed.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Laid-Open No. 9-188761

[0008] Patent Document 2: Japanese Patent Laid-Open No. 10-123532

[0009] Patent Document 3: International Publication No. 2019-082975 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] In a liquid crystal display element using a transverse electric field method such as an IPS driving method or an FFS driving method, a positive liquid crystal has been conventionally used. However, by using a negative liquid crystal, the transmission loss above the electrode can be reduced and the contrast can be improved. Therefore, recently, a liquid crystal display element using a negative liquid crystal has been studied.

[0012] However, the inventors of the present application have conducted studies and found that when negative liquid crystal is used as a liquid crystal material, the incidence of display defects (line burn-in (線焼き付き in Japanese)) is high, and a liquid crystal display element with excellent display quality cannot be obtained.

[0013] In addition, polyimide-based liquid crystal alignment agents usually use highly hygroscopic organic polar solvents such as N-methyl-2-pyrrolidone. Therefore, in the case of obtaining a coating film from a polyimide-based liquid crystal alignment agent containing the above-mentioned organic solvent, the resulting film tends to be easily affected by the environment in which the coating is performed. In particular, when coating is performed in an environment with high humidity, the solubility of the polyimide decreases due to moisture absorption, and the polyimide precipitates, causing the film to become white (hygroscopic whitening). In addition, even if the film that has undergone hygroscopic whitening is dried and heated, the problem of not being able to obtain the original characteristics of the liquid crystal alignment film and the problem of the resulting film having a rough surface arises.

[0014] In addition, when a coating film is obtained by flexographic printing using a polyimide-based liquid crystal aligning agent, the polyimide component precipitates on the flexographic plate, generating printed foreign matter; or the polyimide component precipitates on the nozzle head of the inkjet device, causing clogging of the head, etc., sometimes leading to process defects.

[0015] The object of the present invention is to provide a liquid crystal alignment agent, which can obtain a liquid crystal alignment film having a pretilt angle of less than 1 degree, and obtain a liquid crystal display element with a low incidence of display failure (line burn-in) even when a negative liquid crystal is used as a liquid crystal material. In addition, a liquid crystal alignment agent is provided, which can suppress the whitening phenomenon due to moisture absorption, is not easy to generate foreign matter and clogging when obtaining a coating film, and the surface roughness of the obtained film is less, and even if it is dried or heated, the original characteristics of the liquid crystal alignment film can be exerted.

[0016] The inventors have conducted various studies to achieve the above object, and as a result, have found that a liquid crystal aligning agent having the following structure is the best for achieving the above object, thereby completing the present invention.

[0017] Solutions for solving problems

[0018] Thus, the present invention has the following gist based on the above-mentioned findings.

[0019] A liquid crystal aligning agent comprising a polyimide (A) obtained by imidizing a polyimide precursor which is a reaction product of a tetracarboxylic acid derivative component and a diamine component, wherein the tetracarboxylic acid derivative component comprises 1,2,3,4-butanetetracarboxylic dianhydride or a derivative thereof, and the diamine component comprises at least one diamine selected from the following formulas (1a) to (1b) and a diamine represented by the following formula (2).

[0020]

[0021] In the formula, D represents a divalent saturated hydrocarbon group, unsaturated hydrocarbon group, aromatic hydrocarbon group or heterocyclic ring having 1 to 20 carbon atoms, and D optionally has one or more substituents. E is a single bond, or a divalent saturated hydrocarbon group, unsaturated hydrocarbon group, aromatic hydrocarbon group or heterocyclic ring having 1 to 20 carbon atoms, and E optionally has one or more substituents. F represents a single bond, -O-, -OCO- or -COO-. m is an integer of 0 or 1. A represents an organic group that can be detached by heat. The hydrogen atoms of the benzene ring having an amino group at both ends are optionally substituted by one or more substituents.

[0022] It should be noted that in this specification, Boc represents tert-butoxycarbonyl. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0023] Advantages of the Invention

[0024] By using the liquid crystal aligning agent of the present invention, a liquid crystal alignment film having a pretilt angle of 1 degree or less can be obtained, and even when a negative liquid crystal is used as the liquid crystal material, a liquid crystal display element with a low incidence of display defects (line burn-in) can be obtained. In addition, a liquid crystal aligning agent can be obtained that can suppress the phenomenon of moisture absorption and whitening, is not likely to generate foreign matters, blockages, etc. when forming a coating film, and generates less surface roughness of the obtained film. Moreover, even when dried and heated, the characteristics of the original liquid crystal alignment film can be exhibited. Detailed Description of the Invention

[0025] <Specific Polymer>

[0026] The polyimide (A) contained in the liquid crystal aligning agent of the present invention (hereinafter, also referred to as a specific polymer) is obtained by imidizing a polyimide precursor obtained from a tetracarboxylic acid derivative component containing a specific tetracarboxylic dianhydride and a diamine component containing a specific diamine. The polyimide (A) may be composed of one kind or two or more kinds. It should be noted that examples of the polyimide precursor include polyamic acid or its derivatives (for example, polyamic acid ester).

[0027] Hereinafter, specific examples of the materials used and the manufacturing method will be described in detail.

[0028] <Tetracarboxylic Acid Derivative>

[0029] The tetracarboxylic acid derivative component used for manufacturing the specific polymer of the present invention may use not only tetracarboxylic dianhydride but also tetracarboxylic dihalide compounds, tetraalkyl esters of tetracarboxylic acids, and tetraalkyl ester dihalides as its derivatives. The tetracarboxylic acid derivative component may be used alone with one kind of tetracarboxylic dianhydride or its derivative, or two or more kinds may be used in combination.

[0030] The tetracarboxylic acid derivative component contains 1,2,3,4-butanetetracarboxylic dianhydride or its derivative.

[0031] The preferred content of the above 1,2,3,4-butanetetracarboxylic dianhydride or its derivative is preferably 50 to 100 mol%, more preferably 50 to 95 mol%, and still more preferably 50 to 90 mol% of the total tetracarboxylic acid derivative component.

[0032] As the tetracarboxylic acid derivative component for producing the specific polymer contained in the liquid crystal aligning agent of the present invention, in addition to the above 1,2,3,4-butanetetracarboxylic dianhydride or its derivative, various tetracarboxylic acid derivative components can be used according to the characteristics of the required liquid crystal aligning agent or liquid crystal alignment film.

[0033] If specific preferred examples are listed, they include: acyclic aliphatic tetracarboxylic dianhydrides or their derivatives, alicyclic tetracarboxylic dianhydrides or their derivatives, and aromatic tetracarboxylic dianhydrides or their derivatives other than the above. Here, the aromatic tetracarboxylic dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups including at least one carboxyl group bonded to an aromatic ring. The acyclic aliphatic tetracarboxylic dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups bonded to a chain hydrocarbon structure. Among them, it does not need to be composed only of a chain hydrocarbon structure, and an alicyclic structure or an aromatic ring structure may be present in a part thereof. The alicyclic tetracarboxylic dianhydride is an acid dianhydride obtained by intramolecular dehydration of four carboxyl groups including at least one carboxyl group bonded to an alicyclic structure. Among them, none of these four carboxyl groups are bonded to an aromatic ring. In addition, it does not need to be composed only of an alicyclic structure, and a chain hydrocarbon structure or an aromatic ring structure may be present in a part thereof.

[0034] As the tetracarboxylic acid derivative component, preferably, the substance represented by the following formula (3) is used. The tetracarboxylic dianhydride or its derivative represented by the following formula (3) may be used alone or in combination of two or more.

[0035]

[0036] In the formula, X1 is a structure selected from the following formulas (X1-1) to (X1-25).

[0037]

[0038] In the formulas (X1-1) to (X1-4), R3 to R 23 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group. * represents a bonding bond. From the aspect of liquid crystal alignment property, R3 to R 23Preferably a hydrogen atom, a halogen atom, a methyl group or an ethyl group, more preferably a hydrogen atom or a methyl group.

[0039] In formulas (X1-24) to (X1-25), j and k are integers 0 or 1, and A1 and A2 each independently represent a single bond, -O-, -CO-, -COO-, a phenylene group, a sulfonyl group or an amide group. A plurality of A2s may be the same or different.

[0040] As specific examples of formula (X1-1), the following formulas (X1-1-1) to (X1-1-6) can be cited. From the viewpoint of improving the liquid crystal alignment property, (X1-1-1) is particularly preferred. * Synonymous with the above.

[0041]

[0042] As preferred specific examples of the above formulas (X1-24) and (X1-25), the following formulas (X1-26) to (X1-41) can be cited. * Synonymous with the above.

[0043]

[0044]

[0045] From the viewpoint of improving the liquid crystal alignment property, the above X1 is preferably the above formulas (X1-1) to (X1-3), (X1-5), (X1-7) to (X1-9), (X1-10) or (X1-23), more preferably the above formulas (X1-1-1), (X1-1-2), (X1-2) to (X1-3), (X1-5), (X1-7) to (X1-9), (X1-10) or (X1-23).

[0046] <Specific diamine>

[0047] The diamine component of the polyimide (A) contained in the liquid crystal aligning agent for producing the present invention contains at least one or more diamines selected from the following formulas (1a) to (1b) and the diamine represented by the following formula (2). The diamines represented by the following formulas (1a) to (1b) and the following formula (2) may each be used alone or in combination of two or more.

[0048]

[0049] (In the formula, D represents a divalent saturated hydrocarbon group, unsaturated hydrocarbon group, aromatic hydrocarbon group or heterocyclic ring having 1 to 20 carbon atoms, and D optionally has one or more substituents. E is a single bond, or a divalent saturated hydrocarbon group, unsaturated hydrocarbon group, aromatic hydrocarbon group or heterocyclic ring having 1 to 20 carbon atoms, and E optionally has one or more substituents. F represents a single bond, -O-, -OCO- or -COO-. m is an integer of 0 or 1. A represents an organic group that can be detached by heat. The hydrogen atoms of the benzene ring having amino groups at both ends are optionally substituted by one or more substituents.)

[0050] Examples of the substituent for D or E include: a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkenyl group having 2 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, a carboxyl group, a hydroxyl group, an alkoxycarbonyl group having 1 to 10 carbon atoms, a cyano group, a nitro group, etc.

[0051] The above-mentioned organic group that can be detached by heat is not particularly limited as long as it decomposes by heat to be detached, and thus -NHA is converted to an amino group. Examples of the structure of the organic group that can be detached by heat include: urethane-based organic groups represented by benzyloxycarbonyl, 9-fluorenylmethoxycarbonyl, allyloxycarbonyl, tert-butoxycarbonylgroup, etc. In terms of high efficiency of detachment by heat, detachment at a lower temperature, and the view that harmless gas is discharged during detachment, tert-butoxycarbonyl is particularly preferred. It should be noted that in this specification, an organic group refers to, for example, a hydrocarbon group optionally having a nitrogen atom or an oxygen atom.

[0052] The hydrogen atoms of the benzene ring having amino groups at both ends in the above formula (1a) or (1b) are optionally substituted by substituents, specifically substituted by a halogen atom or an alkyl group having 1 to 5 carbon atoms, etc., and various selections are made according to the availability of reagents, etc., and unsubstituted hydrogen atoms are preferred. In addition, the substitution position of the amino group is not particularly limited. From the viewpoints of synthesis difficulty and reagent availability, when based on the amide bond, the meta-position or para-position is preferred, and from the viewpoint of liquid crystal alignment property, the para-position is particularly preferred. In addition, in an aminobenzene without a protected amino group (i.e., -NHA), when based on the amide bond, the meta-position or para-position is preferred, the meta-position is preferred from the viewpoint of solubility, and the para-position is preferred from the viewpoint of liquid crystal alignment property.

[0053] Examples of the divalent saturated hydrocarbon group having 1 to 20 carbon atoms in D or E in the above formula (1a) or (1b) include: -CH2- or -(CH2) m -(m is an integer of 2 to 20) and other linear alkylene groups; cycloalkylene groups such as cyclobutylene, cyclopentylene or cyclohexylene; or the above -(CH2)m - A group in which a part of the carbon-carbon bonds it has is substituted by the above-mentioned sub-cycloalkyl group.

[0054] As the above-mentioned unsaturated hydrocarbon group, for example, a group in which a part of the carbon-carbon bonds of a saturated hydrocarbon group having 2 to 20 carbon atoms is substituted by a double bond or a triple bond can be cited.

[0055] As the above-mentioned aromatic hydrocarbon group, for example, a benzene ring, a biphenyl structure or a naphthalene ring can be cited.

[0056] As the above-mentioned heterocycle, for example, nitrogen-containing heterocycles such as pyrrole, imidazole, pyrazole, triazole, pyridine, pyrimidine, pyridazine, pyrazine, indole, benzimidazole, purine, quinoline, isoquinoline, naphthyridine, quinoxaline, phthalazine, triazine, carbazole, acridine, piperidine, piperazine, pyrrolidine, hexamethyleneimine, etc. can be cited. Among them, pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole or acridine is preferred.

[0057] The diamine selected from the above formulas (1a) to (1b) is preferably a diamine selected from the following formulas (1-1) to (1-4).

[0058]

[0059] The content of at least one or more diamines selected from the above formulas (1a) to (1b) is preferably 5 to 50 mol%, more preferably 10 to 50 mol%, and further preferably 10 to 40 mol% of all diamine components.

[0060] The hydrogen atoms of the benzene rings having amino groups at both ends in the above formula (2) are optionally substituted by substituents. Specifically, for example, they are substituted by halogen atoms or alkyl groups having 1 to 5 carbon atoms. Various selections are made according to the availability of reagents, etc., and unsubstituted hydrogen atoms are preferred.

[0061] The diamine represented by the above formula (2) is preferably a diamine represented by the following formulas (2-1) to (2-2).

[0062]

[0063] The content of the diamine of the above formula (2) is preferably 50 to 95 mol%, more preferably 50 to 90 mol% of all diamine components.

[0064] As the diamine component of the polyimide (A) contained in the liquid crystal aligning agent of the present invention, in addition to the above-mentioned diamine, various diamines (hereinafter, also referred to as other diamines) can be used according to the characteristics of the required liquid crystal aligning agent.

[0065] Examples of other diamines include: diamine (4) having a structure represented by the following formula (iv) in the molecule; diamine represented by the following formula (O); diamines having a photo-orienting group such as p-diaminoazobenzene or 4,4'-diaminodiphenylacetylene (diaminotolan); diamines having an amide bond or a urea bond such as diamines represented by the following formulas (h-1) to (h-6); 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminobenzophenone, 1,4-bis(4-aminophenyl)benzene, 1,3-bis(4-aminophenyl)benzene, 1,4-bis(4-aminobenzyl)benzene, diamines represented by the following formulas (A-1) to (A-6); diamines having a structure containing at least one nitrogen atom selected from the group consisting of a nitrogen-containing heterocycle, a secondary amino group, and a tertiary amino group (hereinafter, also referred to as a specific nitrogen-containing atom structure); 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol; 4,4'-diamino-3,3'-dihydroxybiphenyl, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid, 3,5-diaminobenzoic acid, and diamines represented by the following formulas (3b-1) to (3b-4) and having a carboxyl group; 4-(2-(methylamino)ethyl)aniline, 4-(2-aminoethyl)aniline, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indan-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-indene-6-amine; diamines having a photopolymerizable group at the terminal such as 2-(2,4-diaminophenoxy)ethyl methacrylate and 2,4-diamino-N,N-diallylaniline; diamines having a steroid skeleton such as cholesteryloxy-3,5-diaminobenzene, cholestenyloxy-3,5-diaminobenzene, cholesteryloxy-2,4-diaminobenzene, cholesteryl 3,5-diaminobenzoate, cholestenyl 3,5-diaminobenzoate, lanostanyl 3,5-diaminobenzoate, and 3,6-bis(4-aminobenzoyloxy)cholestane; diamines represented by the following formulas (V-1) to (V-6); 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); diamines in which two amino groups are bonded to a group represented by any one of the formulas (Y-1) to (Y-167) described in International Publication No. 2018 / 117239. The other diamines may be used alone or in combination of two or more.

[0066]

[0067] (In the above formula (iv), D is an organic group that can be removed by heat. * represents a bonding bond, and at least one of them is bonded to an aliphatic hydrocarbon group.)

[0068]

[0069] (Ar represents a divalent benzene ring, biphenyl structure or naphthalene ring. The two Ars may be the same or different, and any hydrogen atom on the benzene ring, biphenyl structure or naphthalene ring is optionally substituted by a monovalent organic group. p is an integer of 0 or 1. Q2 represents -(CH2) n -(n is an integer from 2 to 18), or at least a part of the -CH2- of this -(CH2) n - is replaced by any one of -O-, -C(=O)- or -O-C(=O)- to form a group.)

[0070]

[0071]

[0072] (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-, -CH2O-, -OCH2-, -COO-, -OCO-, -CON(CH3)- or -N(CH3)CO-, m1 and m2 are each independently an integer from 0 to 4, and m1 + m2 is an integer from 1 to 4. In formula (3b-2), m3 and m4 are each independently an integer from 1 to 5. In formula (3b-3), A 2 represents a straight-chain or branched-chain alkyl group having 1 to 5 carbon atoms, and m5 is an integer from 1 to 5. In formula (3b-4), A 3 and A 4 each independently represent 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 is an integer from 1 to 4.)

[0073]

[0074] (X v1 ~X v4 、X p1 ~X p2 each independently represent -(CH2) a-(a is an integer from 1 to 15), -CONH-, -NHCO-, -CON(CH3)-, -NH-, -O-, -CH2O-, -CH2OCO-, -COO- or -OCO-, X v5 represents -O-, -CH2O-, -CH2OCO-, -COO- or -OCO-. Xa represents a single bond, -O-, -NH-, or -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. The two k's can be the same or different.)

[0075]

[0076] In the diamine (4) having the structure of the above formula (iv) within the above molecule, specific examples of the organic group capable of being thermally detached in D in the above formula (iv) include the structures exemplified in the above A. In addition, from the viewpoint of reducing the incidence of display defects (line burn-in), the above diamine (4) is more preferably an aromatic diamine having one or two benzene rings in the molecule.

[0077] Preferred specific examples of the above diamine (4) include diamines represented by the following formulas (4-1) to (4-5).

[0078]

[0079] The content of the diamine (4) having the structure of the above formula (iv) in the molecule is preferably 5 to 40 mol%, more preferably 5 to 35 mol%, and still more preferably 5 to 30 mol% of all diamine components.

[0080] In the diamine represented by the above formula (O), any hydrogen atom on the benzene ring, biphenyl structure or naphthalene ring is optionally substituted with a monovalent organic group. Examples of the monovalent organic group include: halogen atom, alkyl group having 1 to 10 carbon atoms, alkenyl group having 2 to 10 carbon atoms, alkoxy group having 1 to 10 carbon atoms, fluoroalkyl group having 1 to 10 carbon atoms, fluoroalkenyl group having 2 to 10 carbon atoms, fluoroalkoxy group having 1 to 10 carbon atoms, carboxyl group, hydroxyl group, alkoxycarbonyl group having 1 to 10 carbon atoms, cyano group, nitro group, etc.

[0081] As preferred specific examples of the divalent organic group obtained by removing two amino groups from the diamine represented by the above formula (O), divalent organic groups represented by the following formulas (o-1) to (o-16) can be cited. * represents a bonding bond.

[0082]

[0083] (In formula (o-14), the two m's may be the same or different.)

[0084]

[0085] As the heterocycle containing a nitrogen atom that the diamine having the above specific nitrogen atom-containing structure may optionally have, for example, the heterocycles exemplified above can be cited. Among them, pyridine, pyrimidine, pyrazine, piperidine, piperazine, quinoline, carbazole or acridine are preferred.

[0086] The secondary amino group and the tertiary amino group that the diamine having the above specific nitrogen atom-containing structure may optionally have are represented by the following formula (n), for example.

[0087]

[0088] In the above formula (n), R represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms. "*" represents a bonding bond bonded to the hydrocarbon group.

[0089] As the monovalent hydrocarbon group of R in the above formula (n), for example, the following can be cited: alkyl groups such as methyl, ethyl, and propyl; cycloalkyl groups such as cyclohexyl; aryl groups such as phenyl and methylphenyl. R is preferably a hydrogen atom or a methyl group.

[0090] As specific examples of the diamine having the above specific nitrogen atom-containing structure, for example, the following can be cited: 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 1,4-bis-(4-aminophenyl)-piperazine, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, diamines represented by the following formulas (Dp-1) to (Dp-8), and diamines represented by the following formulas (z-1) to (z-18).

[0091]

[0092]

[0093] <Polymer (B)>

[0094] From the viewpoint of reducing the afterimage derived from the residual DC, the liquid crystal aligning agent of the present invention may also contain a polyimide precursor (B) (hereinafter, also referred to as polymer (B)) which is a reaction product of a tetracarboxylic acid derivative component and a diamine component. The polyimide precursor (B) may be composed of one kind or two or more kinds. As specific examples of the polyimide precursor (B), polyamic acid or its derivatives (for example, polyamic acid ester) can be cited, and polyamic acid is preferred.

[0095] As the tetracarboxylic acid derivative component for obtaining the polymer (B), the following can be cited: acyclic aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, aromatic tetracarboxylic dianhydride or their derivatives. As specific examples of the acyclic aliphatic tetracarboxylic dianhydride, alicyclic tetracarboxylic dianhydride, and aromatic tetracarboxylic dianhydride, the tetracarboxylic dianhydrides or their derivatives exemplified in the above specific polymers can be cited. Among them, as a preferred tetracarboxylic acid derivative component, it is preferably to contain 1,2,3,4 - butanetetracarboxylic dianhydride or its derivatives; tetracarboxylic dianhydrides having at least one partial structure selected from the group consisting of a benzene ring, a cyclobutane ring structure, a cyclopentane ring structure, and a cyclohexane ring structure, or their derivatives, and more preferably 1,2,3,4 - butanetetracarboxylic dianhydride, the compound represented by the above formula (3), or their derivatives. The tetracarboxylic acid derivative component may use one kind of tetracarboxylic dianhydride or its derivatives alone, or may use two or more kinds in combination.

[0096] As the tetracarboxylic acid derivative component for obtaining the polymer (B), preferably, the following can be cited: the tetracarboxylic dianhydride represented by the formula (3) in which X is selected from the above formulas (X1 - 1) to (X1 - 10), (X1 - 21), (X1 - 23) to (X1 - 25); 1,2,3,4 - butanetetracarboxylic dianhydride; or their derivatives.

[0097] The usage ratio of the tetracarboxylic dianhydride represented by the above formula (3), 1,2,3,4 - butanetetracarboxylic dianhydride or their derivatives is preferably 1 to 100 mol%, more preferably 5 to 100 mol%, and further preferably 10 to 100 mol% with respect to 1 mol of all the tetracarboxylic acid derivative components used for synthesizing the polymer (B).

[0098] As the diamine component for obtaining the polymer (B), for example, the diamine components exemplified in the above specific polymers can be cited. Among them, it is preferably to contain at least one diamine selected from the group consisting of diamines having at least one group selected from the group consisting of a urea bond, an amide bond, a carboxyl group, and a hydroxyl group in the molecule (hereinafter, also referred to as diamine (b1)); and diamines having the above - mentioned specific nitrogen - atom - containing structure (hereinafter, also referred to as diamine (b2)). The diamine component may use one kind of diamine alone, or may use two or more kinds in combination.

[0099] The polymer (B) may also be composed of one component or two or more components of polyimide precursors. As more preferable specific examples of the polymer (B), at least one polymer (hereinafter, also referred to as copolymer) selected from the group consisting of polyimide precursors which are reactants of a diamine component containing the above diamine (b1) and the above diamine (b2) and a tetracarboxylic acid derivative component; a mixture of at least one polymer (B-p1) selected from the group consisting of polyimide precursors which are reactants of a diamine component containing the above diamine (b1) and a tetracarboxylic acid derivative component and at least one polymer (B-p2) selected from the group consisting of polyimide precursors which are reactants of a diamine component containing the above diamine (b2) and a tetracarboxylic acid derivative component (hereinafter, also referred to as blend polymer). The above copolymer or blend polymer may be used alone or in combination.

[0100] In the above copolymer, the preferable usage amount of the diamine (b1) is 30 to 100 mol%, more preferably 40 to 100 mol%, and further preferably 50 to 100 mol% relative to the total amount of the diamine components used for manufacturing the polymer (B).

[0101] In the above copolymer, the preferable usage amount of the diamine (b2) is 30 to 100 mol%, more preferably 40 to 100 mol%, and further preferably 50 to 100 mol% relative to the total amount of the diamine components used for manufacturing the polymer (B).

[0102] In the above blend polymer, the preferable usage amounts of the diamine (b1) and the diamine (b2) are respectively 20 to 100 mol% relative to the total amounts of the diamine components used for manufacturing the polymer (B-p1) and the polymer (B-p2). The more preferable usage amount of the diamine (b1) is 20 to 90 mol%, and further preferably 20 to 80 mol% relative to the total amount of the diamine components used for manufacturing the polymer (B-p1). The more preferable usage amount of the diamine (b2) is 20 to 80 mol%, and further preferably 30 to 80 mol% relative to the total amount of the diamine components used for manufacturing the polymer (B-p2).

[0103] As specific examples of the above diamine (b1), the diamines represented by the above formulas (1a) to (1b), the diamine represented by the above formula (4-1), the diamines represented by the above formulas (h-1) to (h-6), 2,4-diaminophenol, 3,5-diaminophenol, 3,5-diaminobenzyl alcohol, 2,4-diaminobenzyl alcohol, 4,6-diaminoresorcinol, 4,4'-diamino-3,3'-dihydroxybiphenyl, 2,4-diaminobenzoic acid, 2,5-diaminobenzoic acid or 3,5-diaminobenzoic acid or the diamines represented by the above formulas (3b-1) to (3b-4) can be cited.

[0104] As specific examples of the above diamine (b2), the diamines exemplified in the above specific polymers can be cited. Among them, the diamines represented by the above formulas (Dp-1) to (Dp-8) and the diamines represented by the above formulas (z-1) to (z-18) are preferred.

[0105] The mass ratio of the content of the above polymer (B-p1) to the content of the above polymer (B-p2) is preferably 5 / 95 to 95 / 5, more preferably 10 / 90 to 90 / 10.

[0106] From the viewpoint of less afterimage derived from residual DC, the content ratio of the specific polymer to the polymer (B) is preferably 10 / 90 to 90 / 10, more preferably 20 / 80 to 90 / 10, and particularly preferably 20 / 80 to 80 / 20 in terms of the mass ratio of [specific polymer] / [polymer (B)].

[0107] <Manufacturing methods of specific polymer and polymer (B)>

[0108] The polyimide precursor used in the present invention can be synthesized, for example, by a known method as described in International Publication WO2013 / 157586.

[0109] In addition, polyimide can be obtained by subjecting the above polyimide precursor to ring closure (imidization). It should be noted that in this specification, the imidization rate refers to the ratio of the imide group to the total amount of the imide group and the carboxyl group (or its derivatives) derived from the tetracarboxylic dianhydride or its derivatives. In polyimide, the imidization rate does not necessarily need to be 100%, and it can be arbitrarily prepared according to the use and purpose. From the viewpoint of reducing the incidence of display defects, the imidization rate of the polyimide (A) of the specific polymer used in the present invention is preferably 20% to 100%, more preferably 50% to 99%, and further preferably 70% to 99%.

[0110] As a method for imidizing the polyimide precursor, for example, thermal imidization in which the solution of the polyimide precursor is directly heated, or catalytic imidization in which a catalyst is added to the solution of the polyimide precursor can be cited.

[0111] When thermally imidizing the polyimide precursor in solution, the temperature is preferably 100 to 400 °C, more preferably 120 to 250 °C, and it is preferably carried out while removing the water generated by the imidization reaction outside the system.

[0112] The catalytic imidization of the polyimide precursor can be carried out as follows: Add a basic catalyst and an acid anhydride to a solution of the polyimide precursor, and stir at -20 to 250 °C, preferably at 0 to 180 °C. The amount of the basic catalyst is 0.5 to 30 molar times, preferably 2 to 20 molar times, of the amic acid group, and the amount of the acid anhydride is 1 to 50 molar times, preferably 3 to 30 molar times, of the amic acid group. Examples of the basic catalyst include pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, etc. Among them, pyridine has an appropriate basicity to promote the reaction, so it is preferred. Examples of the acid anhydride include acetic anhydride, trimellitic anhydride, pyromellitic dianhydride, etc. Among them, if acetic anhydride is used, the purification after the reaction is facilitated, so it is preferred. The imidization rate obtained by catalytic imidization can be controlled by adjusting the amount of the catalyst, the reaction temperature, and the reaction time.

[0113] When recovering the resulting polyimide precursor or polyimide from the reaction solution of the polyimide precursor or polyimide, it is sufficient to add the reaction solution to a solvent to precipitate it. Examples of the solvent for precipitation include methanol, ethanol, isopropanol, acetone, hexane, butyl cellosolve, heptane, methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, water, etc. The polymer precipitated by adding it to the solvent can be dried at normal pressure or reduced pressure, at room temperature or by heating after being recovered by filtration. In addition, if the operation of dissolving the precipitated and recovered polymer in an organic solvent again and performing reprecipitation and recovery is repeated 2 to 10 times, the impurities in the polymer can be reduced. Examples of the solvent at this time include alcohols, ketones, or hydrocarbons, etc. If three or more solvents selected therefrom are used, the purification efficiency is further increased, so it is preferred.

[0114] In the case of the polymer used in the present invention, considering the strength of the resulting liquid crystal alignment film, the workability during film formation, and the coating property, the weight-average molecular weight measured by GPC (Gel Permeation Chromatography) is preferably set to 5000 to 1000000, more preferably 10000 to 150000.

[0115] <Terminal modifier>

[0116] When synthesizing the specific polymer, polymer (B) in the present invention, an appropriate terminal modifier can also be used together with the tetracarboxylic acid derivative component and the diamine component as described above to synthesize a terminal-modified polymer. The terminal-modified polymer has the effects of improving the film hardness of the liquid crystal alignment film obtained by coating and improving the adhesion characteristics between the sealant and the liquid crystal alignment film.

[0117] Examples of the terminal of the specific polymer and polymer (B) in the present invention include: amino group, carboxyl group, acid anhydride group, isocyanate group or their derivatives. The amino group, carboxyl group, acid anhydride group, and isocyanate group are obtained by a general condensation reaction, and the derivatives can be obtained, for example, by modifying the terminal using the following terminal modifiers.

[0118] Examples of the terminal modifier include: acetic anhydride, maleic anhydride, nadic anhydride, phthalic anhydride, itaconic anhydride, cyclohexanedicarboxylic anhydride, 3-hydroxyphthalic anhydride, trimellitic anhydride, compounds represented by the following formulas (m-1) to (m-6), 3-(3-trimethoxysilyl)propyl)-3,4-dihydrofuran-2,5-dione, 4,5,6,7-tetrafluoroisobenzofuran-1,3-dione, 4-ethynylphthalic anhydride and other acid anhydrides; di-tert-butyl dicarbonate, diallyl dicarbonate and other dicarbonate compounds; acryloyl chloride, methacryloyl chloride, nicotinoyl chloride and other chlorocarbonyl compounds; aniline, 2-aminophenol, 3-aminophenol, 4-aminosalicylic acid, 5-aminosalicylic acid, 6-aminosalicylic acid, 2-aminobenzoic acid, 3-aminobenzoic acid, 4-aminobenzoic acid, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine and other monoamine compounds; ethyl isocyanate, phenyl isocyanate, naphthyl isocyanate and other monoisocyanate compounds, etc.

[0119]

[0120] The usage ratio of the terminal modifier is preferably 0.01 to 20 mol parts, more preferably 0.01 to 10 mol parts, based on 100 mol parts in total of the diamine components used.

[0121] <Liquid crystal aligning agent>

[0122] The liquid crystal aligning agent of the present invention contains a specific polymer and, if necessary, polymer (B). The content of the polymer component contained in the liquid crystal aligning agent of the present invention is preferably 0.1 to 30% by mass, more preferably 3 to 10% by mass. The total content of the specific polymer and polymer (B) contained in the liquid crystal aligning agent is preferably 1 to 9% by mass, more preferably 1.5 to 9% by mass. It should be noted that in the case of the total, it also includes the case where one or more of the structural unit elements are 0% by mass.

[0123] In addition to containing a specific polymer and polymer (B), the liquid crystal aligning agent of the present invention may also contain other polymers. Examples of the types of other polymers include: polyimide (B) which is an imidized product of polyimide precursor (B) (wherein, except for polyimide (A) which is a specific polymer), polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivative, polyacetal, polystyrene or its derivative, poly(styrene-phenylmaleimide) derivative, poly(meth)acrylate, etc.

[0124] The liquid crystal aligning agent is a substance used for making a liquid crystal alignment film, and in view of forming a uniform thin film, it is in the form of a coating solution. For the liquid crystal aligning agent of the present invention, a coating solution containing the above polymer components and an organic solvent is preferred.

[0125] The organic solvent contained in the liquid crystal aligning agent is not particularly limited as long as it can uniformly dissolve the polymer components. Specific examples thereof include: N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyl lactamide, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethyl sulfoxide, γ-butyrolactone, γ-valerolactone, 1,3-dimethyl-2-imidazolidinone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 3-methoxy-N,N-dimethyl propionamide, 3-butoxy-N,N-dimethyl propionamide, N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(tert-butyl)-2-pyrrolidone, N-(n-pentyl)-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone (collectively referred to as "good solvents"), etc. Among them, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethyl propionamide, 3-butoxy-N,N-dimethyl propionamide or γ-butyrolactone are 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 preferably uses a mixed solvent in which, in addition to the above solvents, a solvent (also called a poor solvent) that improves the coatability and the surface smoothness of the coating film when coating the liquid crystal aligning agent is used in combination. Specific examples of the organic solvent used in combination are as described below, but are not limited thereto.

[0127] For example, the following can be enumerated: 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, propylene glycol diacetate, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol dimethyl ether, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol acetate, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, diisobutyl ketone (2,6-dimethyl-4-heptanone), etc.

[0128] Among them, 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.

[0129] Examples of the preferred combinations of solvents as good solvents and poor solvents include: N-methyl-2-pyrrolidone, γ-butyrolactone, and ethylene glycol monobutyl ether acetate; N-ethyl-2-pyrrolidone, ethylene glycol monobutyl ether, and ethylene glycol monobutyl ether acetate; N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, and ethylene glycol monobutyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, and propylene glycol monobutyl ether; N-ethyl-2-pyrrolidone and propylene glycol monobutyl ether; N-methyl-2-pyrrolidone, γ-butyrolactone, 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, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether, etc. The content of the poor solvent is preferably 1 to 80% by mass, more preferably 10 to 80% by mass, and particularly preferably 20 to 70% by mass of the total solvent contained in the liquid crystal aligning agent. The type and content of the poor solvent can be appropriately selected according to the coating device, coating conditions, coating environment, etc. of the liquid crystal aligning agent.

[0130] The liquid crystal aligning agent of the present invention may also additionally contain components other than the polymer component and the organic solvent (hereinafter, also referred to as additive components). Examples of such additive components include: adhesion aids for improving the adhesion between the liquid crystal alignment film and the substrate, and the adhesion between the liquid crystal alignment film and the sealant; compounds for improving the strength of the liquid crystal alignment film (hereinafter, also referred to as crosslinkable compounds); dielectrics and conductive substances for adjusting the dielectric constant and resistance of the liquid crystal alignment film; imidization accelerators, etc.

[0131] As the above crosslinkable compound, from the viewpoints of exhibiting good resistance to AC afterimage (the afterimage generated due to the decrease in the alignment performance of the liquid crystal alignment film caused by long-term AC driving) and having a high improvement in film strength, it may be a compound having at least one group selected from the group consisting of an epoxyethyl group, an oxetanyl group, a protected isocyanate group, a protected isothiocyanate group, a group containing an oxazoline ring structure, a group containing a mesitylic acid structure, a cyclic carbonate group, and a group represented by the following formula (d); or a compound selected from the compounds represented by the following formula (e) (hereinafter, they are also 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". * represents a bonding bond. A represents an (m + n)-valent organic group having an aromatic ring. m represents an integer of 1 to 6, and n represents an integer of 0 to 4. The aromatic ring of A is optionally substituted with a monovalent group. Specific examples of the monovalent group include the monovalent organic groups shown as the substituents of Ar in the above formula (O) (excluding alkoxy groups having 1 to 10 carbon atoms).)

[0134] 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 Japanese Patent Laid-Open No. 10-338880 and compounds having a triazine ring in the skeleton described in International Publication No. 2017 / 170483. Among them, it may also be a compound containing a nitrogen atom such as N, N, N', N'-tetraglycidyl-m-xylenediamine, 1,3-bis(N, N-diglycidylaminomethyl)cyclohexane, N, N, N', N'-tetraglycidyl-4,4'-diaminodiphenylmethane, N, N, N', N'-tetraglycidyl-p-phenylenediamine, and the compounds represented by the following formulas (r-1) to (r-3).

[0135]

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

[0170] to

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

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

[0046] to

[0047] of Japanese Patent Laid-Open No. 2014-224978 and compounds having three or more protected isocyanate groups described in paragraphs

[0119] to

[0120] of International Publication No. 2015 / 141598. 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 Japanese Patent Laid-Open No. 2016-200798.

[0140] Specific examples of the compound having a group containing an oxazoline ring structure include compounds containing two or more oxazoline structures described in paragraph

[0115] of Japanese Patent Laid-Open No. 2007-286597.

[0141] As a specific example of a compound having a group containing a mesoionic acid structure, compounds having two or more mesoionic acid structures described in International Publication No. 2012 / 091088 can be cited.

[0142] As a specific example of a compound having a cyclic carbonate group, the compounds described in International Publication No. 2011 / 155577 can be cited.

[0143] As the alkyl group having 1 to 3 carbon atoms for R2 and R3 in the group represented by the above formula (d), methyl, ethyl, propyl, etc. can be cited.

[0144] As specific examples of the compound having the group represented by the above formula (d), compounds having two or more groups represented by the above formula (d) described in International Publication No. 2015 / 072554, paragraph

[0058] of Japanese Patent Laid-Open No. 2016-118753, compounds described in Japanese Patent Laid-Open No. 2016-200798, etc. can also be compounds represented by the following formulae (hd-1) to (hd-8).

[0145]

[0146] As the (m + n)-valent organic group having an aromatic ring in A of the above formula (e), for example, a (m + n)-valent aromatic hydrocarbon group having 6 to 30 carbon atoms, a (m + n)-valent organic group formed by directly bonding or bonding via a linking group an aromatic hydrocarbon group having 6 to 30 carbon atoms, and a (m + n)-valent group having an aromatic heterocycle can be cited. As the above aromatic hydrocarbon, for example, benzene, naphthalene, etc. can be cited. As the aromatic heterocycle, for example, 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, an acridine ring, etc. can be cited. As the above linking group, -NR- (R represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms), an alkylene group having 1 to 10 carbon atoms, or a group formed by removing one hydrogen atom from the above alkylene group, a divalent or trivalent cyclohexane ring, etc. can be cited. It should be noted that any hydrogen atom of the above alkylene group is optionally substituted with an organic group such as a fluorine atom or a trifluoromethyl group. If specific examples are cited, the compounds described in International Publication No. 2010 / 074269, compounds represented by the following formulae (e-1) to (e-10) can be cited.

[0147]

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

[0105] to 55

[0116] of International Publication No. 2015 / 060357 can be cited. In addition, two or more crosslinkable compounds can also 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, more preferably 1 to 15 parts by mass, relative to 100 parts by mass of the polymer component contained in the liquid crystal aligning agent, considering that the crosslinking reaction proceeds and good resistance to AC afterimages is exhibited.

[0150] Examples of such adhesion aids 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-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diaza-nonyl acetate, 9-triethoxysilyl-3,6-diaza-nonyl 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-(3,4-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, 3-isocyanatopropyltriethoxysilane and other silane coupling agents. When using a silane coupling agent, from the viewpoint of exhibiting good resistance to AC afterimages, it is preferably 0.1 to 30 parts by mass, 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] The solid content concentration in the liquid crystal aligning agent (the ratio of the total mass of the components other than the solvent of the liquid crystal aligning agent to the total mass of the liquid crystal aligning agent) is appropriately selected in consideration of viscosity, volatility, etc., and is preferably in the range of 0.5 to 15% by mass, more preferably 1 to 10% by mass.

[0152] The range of the concentration of the particularly preferred solid component varies depending on the method used when coating the liquid crystal aligning agent on the substrate. For example, in the case of using the spin coating method, the concentration of the solid component is particularly preferably in the range of 1.5 to 4.5% by mass. In the case of using the printing method, the concentration of the solid component is particularly preferably set in the range of 3 to 9% by mass, whereby the solution viscosity is set in the range of 12 to 50 mPa·s. In the case of using the inkjet method, the concentration of the solid component is particularly preferably set in the range of 1 to 5% by mass, whereby the solution viscosity is set in the range of 3 to 15 mPa·s.

[0153] <Liquid Crystal Alignment Film / Liquid Crystal Display Element>

[0154] The liquid crystal alignment film of the present invention is obtained from the above liquid crystal aligning agent. The liquid crystal alignment film of the present invention can be used for a horizontally aligned type or a vertically aligned type (VA type) liquid crystal alignment film, and is particularly a liquid crystal alignment film suitable for a horizontally aligned type liquid crystal display element such as an IPS mode or an FFS mode. The liquid crystal display element of the present invention includes the above liquid crystal alignment film. The liquid crystal display element of the present invention can be manufactured, for example, by a method including the following steps (1) to (3).

[0155] (1) Step of coating the liquid crystal aligning agent on the substrate

[0156] For example, the liquid crystal aligning agent of the present invention is coated on one side of a substrate provided with a patterned transparent conductive film by an appropriate coating method such as a roll coater method, a spin coating method, a printing method, an inkjet method, etc. Here, the substrate is not particularly limited as long as it has high transparency, and plastic substrates such as acrylic substrates and polycarbonate substrates can be used together with glass substrates and silicon nitride substrates. In addition, in a reflective liquid crystal display element, if it is only a single substrate, an opaque material such as a silicon wafer can be used, and in this case, an electrode can also be made of a light-reflecting material such as aluminum. In addition, in the case of manufacturing an IPS type or an FFS type liquid crystal element, a substrate provided with an electrode composed of a transparent conductive film or a metal film patterned in a comb shape and a counter substrate not provided with an electrode are used.

[0157] (2) Step of firing the coating film

[0158] After the liquid crystal aligning agent is coated, preheating (pre-baking) is preferably carried out first for the purpose of preventing the liquid of the coated aligning agent from dripping. The pre-baking temperature is preferably 30 to 200 °C, more preferably 40 to 150 °C, and particularly preferably 40 to 100 °C. The pre-baking time is preferably 0.25 to 10 minutes, more preferably 0.5 to 5 minutes. Further, a heating (post-baking) step is preferably carried out. The post-baking temperature is preferably 80 to 300 °C, more preferably 120 to 250 °C. The post-baking time is preferably 5 to 200 minutes, more preferably 10 to 100 minutes. The film thickness of the film thus formed is preferably 5 to 300 nm, more preferably 10 to 200 nm.

[0159] The coating film formed in the above step (1) can be directly used as a liquid crystal alignment film, or the coating film can be subjected to an alignment ability imparting treatment. As the alignment ability imparting treatment, for example, there can be mentioned: a rubbing treatment in which a roll wound with a cloth formed of fibers such as nylon, rayon, and cotton rubs the coating film in a certain direction; a photo-alignment treatment in which polarized or non-polarized radiation is irradiated on the coating film, etc.

[0160] In the photo-alignment treatment, as the radiation irradiated on the coating film, for example, ultraviolet rays and visible light containing light having a wavelength of 150 to 800 nm can be used. In the case where the radiation is polarized, it can be linearly polarized or partially polarized. Further, in the case where the used radiation is linearly polarized or partially polarized, the irradiation can be performed from a direction perpendicular to the substrate surface, from an inclined direction, or they can be combined. In the case where non-polarized radiation is irradiated, the irradiation direction is set as an inclined direction.

[0161] (3) Step of manufacturing a liquid crystal cell

[0162] Prepare two substrates formed with a liquid crystal alignment film as described above, and dispose liquid crystal between the two substrates disposed opposite to each other. Specifically, the following two methods can be mentioned. In the first method, first, the two substrates are disposed opposite to each other with a gap (cell gap) therebetween such that their liquid crystal alignment films face each other. Then, the peripheral portions of the two substrates are bonded using a sealant, and after injecting and filling a liquid crystal composition into the cell gap defined by the substrate surfaces and the sealant to contact the film surface, the injection hole is sealed.

[0163] In addition, the second method is a method called the ODF (One Drop Fill) method. On one of the two substrates on which a liquid crystal alignment film is formed, a UV curable sealant is applied, for example, to a specified portion, and a liquid crystal composition is further dropped onto several specified portions on the surface of the liquid crystal alignment film. Then, the other substrate is attached in a manner such that the liquid crystal alignment films face each other, and the liquid crystal composition is spread over the entire surface of the substrate and brought into contact with the film surface. Next, ultraviolet light is irradiated onto the entire surface of the substrate to cure the sealant. In any case, it is desirable to further heat to a temperature at which the liquid crystal composition used becomes an isotropic phase and then slowly cool to room temperature, thereby removing the flow alignment during liquid crystal filling.

[0164] It should be noted that in the case where the coating film is subjected to a rubbing treatment, the two substrates are arranged so that the rubbing directions in the respective coating films form a specified angle, for example, an orthogonal or antiparallel angle.

[0165] As the sealant, for example, an epoxy resin containing a curing agent and alumina balls as spacers can be used. As the liquid crystal, for example, nematic liquid crystals and smectic liquid crystals can be cited, and among them, nematic liquid crystals are preferred.

[0166] Furthermore, a liquid crystal display element can be obtained by attaching a polarizing plate to the outer surface of the liquid crystal cell as needed. As the polarizing plate attached to the outer surface of the liquid crystal cell, for example, a polarizing plate formed by sandwiching a so-called "H film" which is a polarizing film obtained by stretching and orienting polyvinyl alcohol while absorbing iodine with a cellulose acetate protective film on one side; or a polarizing plate composed of the H film itself can be cited.

[0167] The liquid crystal display element of the present invention can be effectively used in various devices. For example, it can be used in various display devices such as clocks, portable game machines, word processors, notebook computers, car navigation systems, portable cameras, PDAs, digital cameras, mobile phones, smart phones, various monitors, liquid crystal televisions, and information displays.

[0168] Examples

[0169] Hereinafter, the present invention will be specifically described by way of examples and the like, and the present invention is not limited to these examples. It should be noted that the abbreviations of compounds and solvents are as follows.

[0170] (Organic solvent)

[0171] NMP: N - methyl - 2 - pyrrolidone.

[0172] GBL: γ - butyrolactone.

[0173] BCA: ethylene glycol monobutyl ether acetate.

[0174] (Diamine)

[0175] DA-1 to DA-10: Compounds represented by the following structural formulas.

[0176]

[0177] (Tetracarboxylic acid derivatives)

[0178] CA-1 to CA-5: Compounds represented by the following structural formulas.

[0179]

[0180] (Additives)

[0181] AD-1: 3-Glycidoxypropyltriethoxysilane.

[0182] AD-2: Compounds represented by the following structural formulas.

[0183]

[0184] <Viscosity>

[0185] In the synthesis example, the viscosity of the polymer solution was measured using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL, a conical rotor TE-1 (1°34’, R24), and a temperature of 25°C.

[0186] <Determination of the imidization rate of polyimide>

[0187] The imidization rate of the polyimide in the synthesis example was determined as follows. 30 mg of polyimide powder was added to an NMR (nuclear magnetic resonance) sample tube (NMR standard sampling tube, φ5 (manufactured by Kusano Kagaku Co., Ltd.)), and deuterated dimethyl sulfoxide (DMSO-d6, a mixture containing 0.05 mass% TMS (tetramethylsilane)) (0.53 ml) was added, and ultrasonic waves were applied to completely dissolve it. Proton NMR at 500 MHz was measured for this solution using an NMR measuring machine (JNW-ECA500) (manufactured by JEOL DATUM Co., Ltd.). The imidization rate was obtained in the following manner: Protons derived from a structure that does not change before and after imidization were determined as reference protons, and using the peak integral value of this proton and the peak integral value of the proton of the NH group of amic acid that appears in the vicinity of 9.5 ppm to 10.0 ppm, it was obtained using the following formula.

[0188] Imidization rate (%) = (1 - α·x / y) × 100

[0189] In the above formula, x is the integral value of the proton peak derived from the NH group of the amic acid, y is the integral 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%).

[0190] [Synthesis of Polymer]

[0191] (Synthesis Example 1)

[0192] 8.04 g (40.2 mmol) of DA-1, 4.36 g (10.9 mmol) of DA-2, and 12.2 g (21.9 mmol) of DA-3 were measured into a 200 mL four-necked flask equipped with a stirring device and a nitrogen inlet tube, 98.4 g of NMP was added, and it was stirred to dissolve while feeding nitrogen. While stirring the diamine solution under water cooling, 9.40 g (47.4 mmol) of CA-1 was added, 37.6 g of NMP was further added, and it was stirred at 50 °C for 2 hours under a nitrogen atmosphere. 4.65 g (23.7 mmol) of CA-2 was further added, 18.6 g of NMP was further added, and it was stirred at 23 °C for 2 hours under a nitrogen atmosphere to obtain a solution of polyamic acid (PAA-0) (viscosity: 1250 mPa·s).

[0193] 100 g of the above-obtained polyamic acid (PAA-0) solution was taken into a 200 mL Erlenmeyer flask equipped with a stir bar, 1.24 g (5.68 mmol) of di-tert-butyl dicarbonate (hereinafter also referred to as Boc2O) as a terminal modifier was added, and after stirring at 40 °C for 15 hours, a solution of end-modified polyamic acid (PAA-0-1) was obtained.

[0194] 100 g of the above (PAA-0-1) solution was aliquoted into a 200 mL Erlenmeyer flask equipped with a stir bar, 66.7 g of NMP, 14.2 g of acetic anhydride, and 4.70 g of pyridine were added, and after stirring at room temperature for 30 minutes, the reaction was carried out at 60 °C for 4 hours. The reaction solution was poured into 650 g of methanol, and the obtained precipitate was filtered out. After washing the precipitate with methanol, it was dried under reduced pressure at 80 °C to obtain a polyimide powder (imidization rate: 89%).

[0195] Furthermore, 9.60 g of the polyimide powder was aliquoted into a 100 mL Erlenmeyer flask equipped with a stir bar, 70.4 g of NMP was added, and it was stirred at 70 °C for 24 hours to dissolve, obtaining a solution of polyimide (SPI-1).

[0196] <Synthesis Examples 2 to 4>

[0197] Using the diamines and tetracarboxylic acid derivatives shown in Table 1 below, the procedures of Synthesis Example 1 were respectively carried out, whereby solutions of polyimides (SPI-2) to (SPI-4) shown in Table 1 below were obtained. In Table 1, for the values recorded below the compound names, for the tetracarboxylic acid derivative component, it represents the mass (g) of the tetracarboxylic acid derivative used for synthesis, and for the diamine component, it represents the mass (g) of the diamine used for synthesis. For the end-capping treatment, the example recorded as Boc2O was carried out according to the same procedure as in Synthesis Example 1.

[0198] [Table 1]

[0199]

[0200] <Synthesis Examples 5 to 11>

[0201] Using the diamines and tetracarboxylic acid derivatives shown in Table 2 below, the procedures of Synthesis Example 1 were respectively carried out, whereby solutions of polyamic acids (PAA-1) to (PAA-7) shown in Table 2 below were obtained. In Table 2, for the values recorded below the compound names, for the tetracarboxylic acid derivative component, it represents the mass (g) of the tetracarboxylic acid derivative used for synthesis, and for the diamine component, it represents the mass (g) of the diamine used for synthesis.

[0202] [Table 2]

[0203]

[0204] [Preparation of Liquid Crystal Alignment Agent]

[0205] <Examples 1 to 6, Comparative Examples 1 to 5>

[0206] Into sample tubes, solutions of the polyamic acids and polyimides obtained in Synthesis Examples 1 to 11 in the amounts shown in the following table were respectively weighed, and further NMP, GBL, BCA, a GBL solution containing 1% by mass of AD-1, and an NMP solution containing 10% by mass of AD-2 in the amounts shown in the following table were respectively weighed and added while stirring. Stirring was carried out at room temperature for 2 hours, whereby liquid crystal alignment agents (1) to (11) were obtained.

[0207] [Table 3]

[0208]

[0209] [Table 4]

[0210]

[0211] Hereinafter, a method for fabricating a liquid crystal display element for evaluating the pretilt angle and the voltage holding ratio is shown.

[0212] [Fabrication of Liquid Crystal Display Element]

[0213] First, a substrate with electrodes was prepared. The substrate was a glass substrate with a size of 30 mm × 40 mm and a thickness of 1.1 mm. An ITO electrode with a film thickness of 35 nm was formed on the substrate, and the electrode was a stripe pattern with a length of 40 mm and a width of 10 mm.

[0214] Next, the liquid crystal aligning agent obtained above was filtered through a filter with a pore diameter of 1.0 μm, and then it was coated on the prepared substrate with the above electrodes by spin coating. After drying on a hot plate at 80 °C for 2 minutes, firing was carried out in an IR oven at 230 °C for 20 minutes to form a coating film with a film thickness of 100 nm, and a substrate with a liquid crystal alignment film was obtained. After rubbing this liquid crystal alignment film with a rayon cloth (roller diameter: 120 mm, roller rotation speed: 1000 rpm, moving speed: 20 mm / sec, indentation length: 0.4 mm), ultrasonic waves were irradiated in pure water for 1 minute for cleaning, and after removing water droplets by blowing, it was dried at 80 °C for 10 minutes to obtain a substrate with a liquid crystal alignment film. Two such substrates with liquid crystal alignment films were prepared. After scattering 4-μm spacers on one of the liquid crystal alignment film surfaces, a sealant was printed from above, and the other substrate was bonded in such a way that the rubbing direction was opposite and the film surfaces faced each other, and then the sealant was cured to fabricate an empty cell. A negative liquid crystal MLC-7026 (manufactured by MERCK) was injected into the empty cell by a vacuum injection method, and the injection port was sealed to obtain a liquid crystal cell. Then, the obtained liquid crystal cell was heated at 120 °C for 1 hour and left overnight at 23 °C for each evaluation.

[0215] <Pretilt Angle>

[0216] An AxoScan Mueller matrix polarimeter manufactured by OPTOMETRICS was used to evaluate the pretilt angle in the above liquid crystal display element. The lower the value of the pretilt angle, the better.

[0217] <Voltage Holding Ratio>

[0218] A voltage of 1 V was applied to the above liquid crystal display element at a temperature of 60 °C for 60 μsec, and the voltage after 500 msec was measured. How much the voltage could be maintained was evaluated as the voltage holding ratio. The higher the value of the voltage holding ratio, the better. It should be noted that it is known that when the voltage holding ratio, which is one of the electrical characteristics of a liquid crystal display element, increases, line burn-in, which is one of the display defects of a liquid crystal display element, is less likely to occur.

[0219] Regarding the liquid crystal display elements having liquid crystal alignment films obtained using the respective liquid crystal aligning agents of the above-described Examples 1 to 6 and Comparative Examples 1 to 5, the results of the above-described pretilt angle evaluation and voltage holding ratio evaluation are shown in Table 5 below.

[0220] [Table 5]

[0221]

[0222] <Evaluation of whitening characteristics>

[0223] 0.1 mL of the liquid crystal aligning agents obtained in Examples 1 to 6 and Comparative Examples 1 to 5 was dropped onto a chromium substrate and allowed to stand in an environment at a temperature of 23°C and a humidity of 68%. The edge and central portions of the droplet were observed with an optical microscope, and the time until the precipitation occurred was measured.

[0224] Note that, in this evaluation, the phenomenon in which the dissolved polyimide precipitates or aggregates, causing the droplet to become cloudy, is defined as the whitening phenomenon. The state where the droplet is completely not whitened is designated as "〇", the state where only the edge of the droplet is whitened is designated as "△", and the state where the entire surface of the droplet is whitened is designated as "×" for evaluation. The longer the time to become 〇, the better.

[0225] [Table 6]

[0226]

[0227] By using the liquid crystal aligning agent of the embodiment of the present invention, a liquid crystal alignment film having a pretilt angle of 1 degree or less was obtained, and even when a negative liquid crystal was used as the liquid crystal material, a liquid crystal display element having a high voltage holding ratio (i.e., a liquid crystal display element having a low incidence of display defects (line burn-in)) was obtained.

[0228] Furthermore, by using the liquid crystal aligning agent of the embodiment of the present invention, a liquid crystal aligning agent can be obtained that can suppress the moisture absorption whitening phenomenon, is less likely to generate foreign matter, clogging, etc. when forming a coating film, and the generation of surface roughness of the obtained film is small, and moreover, even when dried and heated, the characteristics of the original liquid crystal alignment film can be exhibited.

[0229] Industrial applicability

[0230] The liquid crystal display element produced using the liquid crystal aligning agent of the present invention can be made into a liquid crystal display element having excellent display quality, and is preferably used for display elements of various modes represented by horizontal alignment type liquid crystal display elements such as the IPS mode or the FFS mode.

[0231] It should be noted that the entire contents of the specification, claims, drawings, and abstract of Japanese Patent Application No. 2020-071204 filed on April 10, 2020 are incorporated herein by reference as the disclosure of the specification of the present invention.

Claims

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

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

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

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

5. The liquid crystal aligning agent according to claim 1 or 2, wherein the imidization rate of the polyimide (A) is 20% to 100%.

6. The liquid crystal aligning agent according to claim 1 or 2, wherein the tetracarboxylic acid derivative component further contains at least one tetracarboxylic dianhydride or its derivative represented by the following formula (3), wherein X1 is a structure selected from the following structures, R3 to R 17 each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms containing a fluorine atom, or a phenyl group; * represents a bonding bond.

7. The liquid crystal aligning agent according to claim 1 or 2, wherein at least one diamine selected from the formulas (1a) to (1b) is at least one diamine selected from the following formulas (1 - 1) to (1 - 4), Boc represents tert - butyloxycarbonyl.

8. The liquid crystal aligning agent according to claim 1 or 2, wherein the diamine component further contains at least one diamine (4) having the following structure (iv) in the molecule, in the formula (iv), D is an organic group that can be detached by heat; * represents a bonding bond, and at least one of them is bonded to an aliphatic hydrocarbon.

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

10. The liquid crystal aligning agent according to claim 1 or 2, wherein the liquid crystal aligning agent further contains a polyimide precursor (B) which is a reaction product of a tetracarboxylic acid derivative component and a diamine component.

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

12. The liquid crystal aligning agent according to claim 10, wherein, the diamine component used to obtain the polyimide precursor (B) contains at least one diamine selected from the group consisting of diamine (b1) and diamine (b2), the diamine (b1) has at least one group selected from the group consisting of a urea bond, an amide bond, a carboxyl group, and a hydroxyl group in the molecule; the diamine (b2) has at least one nitrogen-containing atom structure selected from the group consisting of a nitrogen-containing heterocycle, a secondary amino group, and a tertiary amino group.

13. The liquid crystal aligning agent according to claim 1 or 2, wherein, the polyimide (A) and / or the polyimide precursor (B) is a polyimide and / or a polyimide precursor modified at the terminal.

14. The liquid crystal aligning agent according to claim 1 or 2, wherein, the liquid crystal aligning agent further contains a crosslinkable compound and / or an adhesion aid.

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

16. A liquid crystal display element including the liquid crystal alignment film according to claim 15.

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