Liquid crystal aligning agent, liquid crystal alignment film, liquid crystal display element, and method for producing the same

Abstract

To provide a liquid crystal display element, a liquid crystal alignment film, and a liquid crystal aligning agent, characterized by being from defects including display unevenness and high light transmittance.SOLUTION: A liquid crystal aligning agent comprises a polymer selected from a polyimide precursor and a polyimide each having a structural unit represented by formula [A1], and a compound selected from formulas [C1] to [C4]. (Each symbol of the formulas is defined in the specification).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal aligning agent used in the production of a liquid crystal display element, a liquid crystal alignment film obtained from the liquid crystal aligning agent, and a liquid crystal display element using the liquid crystal alignment film. [Background technology]

[0002] Currently, highly durable polyimide-based organic films are used in industrially utilized resin coatings. In particular, these polyimide-based organic films are also used as liquid crystal alignment films for liquid crystal display elements. Polyimide-based liquid crystal alignment films are formed from liquid crystal alignment agents containing polyimide precursors such as polyamic acid and polyimide (see, for example, Patent Document 1). In LCD devices using horizontal electric field driving methods such as IPS (In Plane Switching) and FFS (Fringe Field Switching), the liquid crystal alignment film after baking is usually rubbed in a certain direction with a roll wrapped in cloth made of fibers such as nylon, rayon, or cotton to align the liquid crystal horizontally.

[0003] In recent years, as liquid crystal display elements have become larger and more precise, problems have arisen, such as scratches and dust generation on liquid crystal alignment films caused by rubbing treatment, and poor in-plane uniformity of liquid crystal alignment. In response to these problems, a new alignment treatment method has begun to be adopted, in which the alignment of liquid crystals is controlled by irradiating the liquid crystals with polarized radiation (light) (also known as photo-alignment treatment). As this photo-alignment treatment, methods utilizing photoisomerization reaction, photo-crosslinking reaction, and photodecomposition reaction have been proposed (see, for example, Patent Document 2 and Patent Document 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 9-278724 [Patent Document 2] Japanese Patent Publication No. 9-297313 [Patent Document 3] Japanese Patent Application Publication No. 2004-206091 Summary of the Invention [Problem to be solved by the invention]

[0005] In the manufacturing process of liquid crystal display elements, liquid crystal alignment agents for preparing liquid crystal alignment films are sometimes stored at room temperature for long periods of time. However, polyimide polymers, especially polyimide precursors, have low stability at room temperature and undergo decomposition and oxidation reactions. As a result, liquid crystal alignment agents containing polyimide polymers tend to experience a decrease in viscosity and strong coloration, which can lead to uneven coating and thickness variations in the liquid crystal alignment film and coloration of the liquid crystal alignment film. As liquid crystal display elements become larger and higher definition, the quality requirements for liquid crystal display elements are becoming stricter. Therefore, liquid crystal display elements are required to have no defects such as display unevenness and to have high transmittance. Therefore, an object of the present invention is to provide a liquid crystal aligning agent that does not cause a decrease in viscosity or coloration by using a polyimide polymer having a specific structure and a compound having a specific structure. In particular, an object of the present invention is to provide the liquid crystal aligning agent with its effects even when stored for a long period of time. Another object of the present invention is to provide a liquid crystal alignment film using the liquid crystal aligning agent that does not cause uneven coating, non-uniform film thickness, or coloration. Another object of the present invention is to provide a liquid crystal display element equipped with a liquid crystal alignment film that meets the above requirements. [Means for solving the problem]

[0006] As a result of intensive research by the inventors to achieve the above object, the present invention has been completed, which has the following gist. That is, it is a liquid crystal aligning agent containing the following components (A) and (B). Component (A): At least one polymer (also referred to as a specific polymer) selected from polyimide precursors having a structural unit of the following formula [A1] and polyimides which are imide compounds of the polyimide precursors. Component (B): At least one compound (also referred to as a specific compound) selected from the following formulae [C1] to [C4]. [ka] (X A represents a tetravalent organic group derived from a tetracarboxylic acid component. Y A R represents a divalent organic group derived from a diamine component. A R each independently represents a hydrogen atom or a monovalent organic group. B each independently represents a hydrogen atom or a monovalent organic group. [ka] (Ar represents a monovalent aromatic ring group. The moieties represented by solid and broken lines as shown below represent single or double bonds. m represents an integer of 1 to 4. R c represents an alkyl group having 1 or 3 carbon atoms. [ka]

[0007] The following terms and abbreviations used in this specification represent the following: The halogen atom refers to a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, or the like. * indicates a bond in each case. Boc represents a tert-butoxycarbonyl group, and Fmoc represents a 9-fluorenylmethoxycarbonyl group. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a liquid crystal aligning agent that does not undergo change in viscosity or coloration even when stored at room temperature for a long period of time, and therefore, a liquid crystal alignment film prepared using the agent does not suffer from unevenness in coating film, non-uniformity in film thickness, or coloration, and therefore a liquid crystal display element with excellent display quality can be obtained. The mechanism by which the present invention provides a liquid crystal display device having the above-mentioned excellent characteristics is not entirely clear, but is presumed to be as follows. It is believed that by using the specific compound together with the specific polymer in the liquid crystal aligning agent, the oxidation reaction of the specific polymer component is suppressed, and thus the viscosity change and coloration of the liquid crystal aligning agent can be suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing an example of a lateral electric field type liquid crystal display element of the present invention. [Figure 2] FIG. 10 is a schematic cross-sectional view showing another example of a lateral electric field type liquid crystal display element of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] <Specific polymer> The specific polymer is at least one polymer selected from a polyimide precursor having a structural unit of the above formula [A1] and a polyimide which is an imide compound of the polyimide precursor. The polyimide precursor and polyimide (also collectively referred to as "polyimide polymer") in the present invention are obtained using a tetracarboxylic acid component and a diamine component. The polyimide precursor is preferably a polyamic acid or a polyamic acid ester having the structure of the following formula [A]. [ka] (R a R represents a tetravalent organic group derived from a tetracarboxylic acid component. b represents a divalent organic group derived from a diamine component. 1 A each independently represents a hydrogen atom or a monovalent organic group. 2 each independently represents a hydrogen atom or a monovalent organic group, and n represents a positive integer. Polyimide has a structure of the following formula [A-4] and can be obtained by ring-closing (also called imidization) a polyamic acid of a polyimide precursor. In this case, if the ring-closing rate (also called imidization rate) of the amic acid group is less than 100%, the polyimide contains at least one of the structures of the following formulas [A-1] to [A-3] in addition to the structure of formula [A-4]. [ka] (R a , R b , A 1 and A 2 has the same meaning as defined in the above formula [A].

[0011] The diamine component is a diamine having two primary or secondary amino groups in the molecule, and the tetracarboxylic acid component includes a tetracarboxylic acid compound, a tetracarboxylic acid dianhydride, a tetracarboxylic acid dihalide compound, a tetracarboxylic acid dialkyl ester compound, and a tetracarboxylic acid dialkyl ester dihalide compound. The polyimide polymer is preferably a polyamic acid having a structural formula of a repeating unit of the following formula [D] or a polyimide obtained by imidizing the polyamic acid, because the polyimide polymer can be obtained relatively easily by using a tetracarboxylic dianhydride of the following formula [B] and a diamine of the following formula [C] as raw materials. [ka] (R a and R b has the same meaning as defined in the above formula [A]. [ka] (R a , R b and n are as defined in formula [A] above.

[0012] In addition, by a conventional synthesis method, the polymer of formula [D] is converted into A of formula [A]. 1 and A in formula [A] 2 It is also possible to introduce a monovalent organic group of the formula: X in the formula [A1] A , Y A , R A and R B The details of the above are as described above, but the following are preferred for each. Specific X AAs the formula [X A -1]~expression[X A -25] are listed. [ka] [ka] [ka] (R x are each independently at least one selected from a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, a monovalent organic group having 1 to 6 carbon atoms and a fluorine atom, and a phenyl group. * represents a bond.

[0013] Among them, the formula [X A -1], expression [X A -3], expression [X A -4], expression [X A -7], formula [X A -8] or formula [X A -9] is preferred. More preferred is a compound of the formula [X A -1], expression [X A -3], expression [X A -4] or formula [X A Particularly preferred is a compound of the formula [X A -1]. The more specific formula [X A -1] is the following formula [X A -1-1] ~ expression [X A -1-5], and it is preferable to use these. [ka]

[0014] Furthermore, X A The following formula [X B -1]~expression[X B -21], which can also be used. [ka] [ka]

[0015] X in formula [A1] A may contain other structures than those mentioned above. A One or more types of the structure may be used depending on the properties. Specific examples of other structures include tetravalent organic groups derived from tetracarboxylic dianhydrides of the following formulae [CA1] to [CA24]. [ka] [ka] [ka]

[0016] Y in the formula [A1] A is expressed by the following formula [Y A −1] and the formula [Y A -2] is preferably at least one selected from the following: [ka]

[0017] R Y are each independently at least one selected from a halogen atom, a hydroxy group, an amino group which may be protected, a thiol group, a nitro group, a phosphate group, and a monovalent organic group having 1 to 20 carbon atoms. Of these, a halogen atom, a hydroxy group, an amino group which may be protected, a methyl group, a methoxy group, or a monovalent group in which at least one hydrogen atom of an alkyl group having 1 to 3 carbon atoms has been substituted with a halogen atom or an amino group which may be protected with a protecting group is preferred. A Yrepresents at least one selected from an ester bond, an amide bond, a thioester bond, and a divalent organic group having 2 to 20 carbon atoms, provided that a 1,4-phenylene group, 1 to 4 of the hydrogen atoms on the phenylene group are R Y However, divalent organic groups substituted with R, or divalent organic groups formed by linking these divalent organic groups together, are excluded. Y represents an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, an alkynyl group having 2 to 10 carbon atoms, or a hydrocarbon group in which any methylene group is -O-, -S-, -C(=O)-, -C(=O)-O-, -C(=O)-S-, -NR 3 -, -CO-NR 3 -, -Si(R 3’ )2-, -S(=O)2- (where R 3 represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 10 carbon atoms, or a tert-butoxycarbonyl group. 3’ represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms.

[0018] Among these, from the viewpoint of suitably obtaining the effects of the present invention, the group "-L1-A-L1'-" or a divalent organic group having 2 to 20 carbon atoms and a heterocycle is preferred. L1 and L1' each independently represent a single bond, -O-, -NR-, -C(=O)-NR-, -C(=O)-, or -OC(=O)- (R represents a hydrogen atom, a monovalent hydrocarbon group having 1 to 5 carbon atoms, or a tert-butoxycarbonyl group). A is an alkylene group having 1 to 12 carbon atoms, -CH=CH-, -C≡C-, or -CR 0 =CR 0’ -C(=O)-O-, or -O-, -NR-, -C(=O)-NR-, -C(=O)-NR-C(=O)-, -C(=O)-O-, -Si(R a )2- and -O-C(=O)- are divalent organic groups into which at least one group of -O-Ar-O-, -O-C(=O)-Ar-C(=O)-O-, and -C(=O)-O-Ar-O-C(=O)-. 0 and R 0’are each independently a hydrogen atom or a methyl group. R is a hydrogen atom, a monovalent hydrocarbon group having 1 to 5 carbon atoms, or a tert-butoxycarbonyl group. R a represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 3 carbon atoms. Ar represents a phenylene group or a biphenyl structure. However, when L1 and L1' are single bonds, A represents a group other than a methylene group.

[0019] Examples of the divalent organic group having 2 to 20 carbon atoms and having a heterocycle include a piperidine ring, a piperazine ring, a morpholine ring, a pyrrolidine ring, a pyrrole ring, a furan ring, a thiophene ring, an imidazole ring, a pyrazole ring, an imide ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, a pyridine ring, a pyrimidine ring, a pyridazine ring, or a divalent organic group having 2 to 20 carbon atoms and having a pyrazine ring or a fused ring containing any of these ring structures as part of its structure, and the hydrogen atoms on these rings may be substituted with halogen atoms, methyl groups, or methoxy groups. Each a1 independently represents an integer of 0 to 4. Of these, an integer of 0 to 2 is preferred. When there are multiple a1's, they may be the same or different. a represents an integer of 1 to 4. Among these, an integer of 1 or 2 is preferred. b and c each independently represent an integer of 1 or 2;

[0020] The specific formula [Y A −1] and the formula [Y A -2] is expressed by the following formula [Y A -1-1]~Formula [Y A -1-57], and it is preferable to use these. [ka] [ka] [ka] [ka] [ka] [ka] [ka]

[0021] (In the above formula, the bonding positions of the benzene ring bonded to * are 1,4-positions. A The bonding positions of all benzene rings in [Y-1-9] are 1,4-positions. In the formula, -(CH2)0- represents a single bond. A In formula [Y A In formula [Y A -1-11] and the formula [Y A -1-12], the sum of m1, m2 and n represents an integer of 3 to 12.

[0022] Among them, the above-mentioned formula [Y A -1-1], the formula [Y A -1-6], the formula [Y A -1-9], the formula [Y A -1-10], the formula [Y A -1-13], the formula [Y A -1-15], the formula [Y A -1-17]~Formula [Y A -1-27], the formula [Y A -1-46] or the formula [Y A -1-52]~Formula [Y A -1-57] is preferred. More preferred is a compound represented by the formula [Y A -1-1], the formula [Y A -1-9], the formula [Y A -1-10], the formula [Y A -1-15], the formula [Y A -1-17]~Formula [Y A -1-19], the formula [Y A -1-23], the formula [YA -1-25]~Formula [Y A -1-27], the formula [Y A -1-46] or the formula [Y A -1-52]~Formula [Y A -1-55]. Y in formula [A1] A may contain other structures than those described above. A One or more types of the structure may be used depending on the properties.

[0023] Specific examples of other structures include divalent organic groups derived from the following diamines: 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, 3,6-diaminoacridine, N-ethyl-3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, 4,4'-diaminodiphenylamine, 4,4'-diaminodiphenyl-N-methylamine, 4,4'-diaminobiphenyl-3-carboxylic acid, 4,4'-diaminodiphenylmethane-3-carboxylic acid, 1,2-bis(4-aminophenyl)-2,3-diamine ...ridine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine, 2,4-diaminopyrimidine 4,4'-Diaminobiphenylethane-3,3'-dicarboxylic acid, 4,4'-Diaminobiphenyl-2,2'-dicarboxylic acid, 3,3'-Diaminobiphenyl-4,4'-dicarboxylic acid, 3,3'-Diaminobiphenyl-2,4'-dicarboxylic acid, 4,4'-Diaminodiphenylmethane-3,3'-dicarboxylic acid, 1,2-Bis(4-aminophenyl)ethane-3,3'-dicarboxylic acid, 4,4'-Diaminodiphenylether-3,3'-dicarboxylic acid, 1,2-Bis(6-amino-2-naphthalene)ethane-3,3'-dicarboxylic acid aromatic diamines having a naphthalene ring such as 1,2-bis(6-amino-2-naphthyl)ethane, 1,2-bis(6-amino-2-naphthyl)ethane, or 6-[2-(4-aminophenoxy)ethoxy]-2-naphthylamine, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminobenzophenone, 4-(2-(methylamino)ethyl)aniline amine, 4-(2-aminoethyl)aniline, 1-(4-aminophenyl)-1,3,3-trimethyl-1H-indan-5-amine, 1-(4-aminophenyl)-2,3-dihydro-1,3,3-trimethyl-1H-inden-6-amine, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-3,5-diaminobenzene, cholestanyloxy-2,4-diaminobenzene, cholestanyl 3,5-diaminobenzoate, cholestanyl 3,5-diaminobenzoate, lanostaniyl 3,5-diaminobenzoate and 3,Examples of such diamines include diamines having a steroid skeleton such as 6-bis(4-aminobenzoyloxy)cholestane, diamines having a siloxane bond such as 1,3-bis(3-aminopropyl)-tetramethyldisiloxane, metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 1,3-bis(aminomethyl)cyclohexane, 1,4-diaminocyclohexane, 4,4'-methylenebis(cyclohexylamine), and diamines having two amino groups bonded to a group represented by any one of formulas (Y-1) to (Y-167) described in WO2018 / 117239.

[0024] Furthermore, divalent organic groups derived from diamines of the following formulae [DA-1] to [DA-93] can also be used. [ka] [ka] [ka] [ka]

[0025] [ka] [ka] [ka]

[0026] [ka] [ka]

[0027] [ka] [ka]

[0028] In order to suitably obtain the effects of the present invention, the structural unit of the formula [A1] preferably accounts for 10 to 100 mol %, more preferably 15 to 100 mol %, of all structural units of the specific polymer. The method for synthesizing the polyimide polymer is not particularly limited. Typically, it is obtained by reacting a diamine component with a tetracarboxylic acid component. Specific examples include the method described on pages 35 and 36 of International Publication WO2015 / 012368 (published January 29, 2015). Examples of methods for synthesizing the polyamic acid ester include a known method of reacting a polyamic acid of a polyimide precursor obtained by reacting a diamine component with a tetracarboxylic acid component with an esterifying agent, a method of reacting the tetracarboxylic acid diester with a diamine, or a method of reacting the tetracarboxylic acid diester dihalide with a diamine.

[0029] The reaction between the diamine component and the tetracarboxylic acid component is usually carried out in a solvent containing the diamine component and the tetracarboxylic acid component. The solvent used is not particularly limited as long as it dissolves the produced polyimide precursor. Specific examples include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, γ-butyrolactone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and 1,3-dimethyl-imidazolidinone. Furthermore, when the polyimide precursor has high solvent solubility, methyl ethyl ketone, cyclohexanone, cyclopentanone, 4-hydroxy-4-methyl-2-pentanone, or solvents represented by the following formulas [D1] to [D3] can be used. [ka] (D 1 and D 2represents an alkyl group having 1 to 3 carbon atoms. 3 represents an alkyl group having 1 to 4 carbon atoms.

[0030] These may be used alone or in combination. Furthermore, even if a solvent does not dissolve the polyimide precursor, it may be mixed with the solvent to the extent that it does not precipitate. Furthermore, since moisture in the solvent inhibits the polymerization reaction and further causes hydrolysis of the polyimide precursor, it is preferable to use a solvent that has been dehydrated and dried. In the polymerization reaction of the polyimide precursor, the total number of moles of the tetracarboxylic acid components is preferably 0.8 to 1.2 when the total number of moles of the diamine components is 1.0. When the total number of moles of the tetracarboxylic acid components is less than 1.0, i.e., when the total number of moles of the tetracarboxylic acid components is smaller than the number of moles of the diamine components, the polymer ends in an amino group structure, and when the total number of moles of the tetracarboxylic acid components is greater than 1.0, i.e., when the total number of moles of the tetracarboxylic acid components is greater than the number of moles of the diamine components, the polymer ends in a carboxylic acid anhydride or dicarboxylic acid structure. Polyimides are obtained by ring-closing a polyimide precursor, and the imidization rate does not necessarily need to be 100% and can be adjusted as desired depending on the application and purpose. From the viewpoint of solubility in solvents, an imidization rate of 40 to 90% is preferred, and 50 to 80% is more preferred. The polyimide polymer may be converted into an end-capping polymer by using an end-capping agent. The end-capping polymer has the effect of increasing the film hardness of the liquid crystal alignment film and improving the adhesion between the liquid crystal alignment film and the sealant in a liquid crystal display element.

[0031] The method for obtaining the terminal-capping polymer is not particularly limited. Specific examples include the method described on pages 24 and 25 of International Publication WO2023 / 074568 (published May 4, 2023). In this case, the proportion of the terminal-capping agent used is preferably 0.01 to 20 molar parts per 100 molar parts of all diamine components. More preferably, it is 0.01 to 10 molar parts. From the viewpoints of the strength of the liquid crystal alignment film obtained therefrom, workability during film formation, and coating properties, the molecular weight of the polyimide polymer is preferably 5,000 to 1,000,000, more preferably 10,000 to 150,000, in terms of Mw (weight average molecular weight) measured by GPC (Gel Permeation Chromatography).

[0032] <Specific compound> The specific compound is at least one compound selected from the formulae [C1] to [C4]. Details of the formulae [C1] to [C4] are as described above, but the following are preferred for each. The formula [C1] is a compound in which at least one of the 2- to 6-positions of benzoic acid is substituted with a hydroxy group. A specific example is salicylic acid, which is preferably used. The formula [C2] is a compound in which at least three of the 2- to 6-positions of benzoic acid are substituted with hydroxy groups. A specific example is gallic acid, which is preferably used. Specific examples of the formula [C3] include apigenin, acacetin, chrysin, and naringenin, and it is preferable to use these. Specific examples of the formula [C4] include methyl gallate and propyl gallate, and it is preferable to use these. From the viewpoint of suitably obtaining the effects of the present invention, the use ratio of the specific compound is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and particularly preferably 0.3 parts by mass or more, based on 100 parts by mass of the polymer component contained in the liquid crystal aligning agent. Furthermore, when the polymer component contained in the liquid crystal aligning agent is taken as 100 parts by mass, the content is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and particularly preferably 15 parts by mass or less.

[0033] <Liquid crystal alignment agent> The liquid crystal aligning agent is a solution for forming a liquid crystal alignment film, and is a solution containing a specific polymer, a specific compound, and a solvent. The polymer components do not necessarily have to be all specific polymers, and polyimide-based polymers other than the specific polymers or polymers other than polyimide-based polymers may be mixed. Specific examples include polysiloxane, polyester, polyamide, polyurea, polyorganosiloxane, cellulose derivatives, polyacetal, polystyrene derivatives, poly(styrene-maleic anhydride) copolymers, poly(isobutylene-maleic anhydride) copolymers, poly(vinyl ether-maleic anhydride) copolymers, poly(styrene-phenylmaleimide) derivatives, and poly(meth)acrylates. Specific examples of poly(styrene-maleic anhydride) copolymers include SMA1000, SMA2000, and SMA3000 (manufactured by Cray Valley), and GSM301 (manufactured by Gifu Ceramics Manufacturing Co., Ltd.). Specific examples of poly(isobutylene-maleic anhydride) copolymers include ISOBAM-600 (manufactured by Kuraray Co., Ltd.). A specific example of a poly(vinyl ether-maleic anhydride) copolymer is Gantrez AN-139 (methyl vinyl ether maleic anhydride resin, manufactured by Ashland). When a polymer other than the specific polymer is used as the polymer component, the proportion of the other polymer used is preferably 90 parts by mass or less, more preferably 80 parts by mass or less, and most preferably 70 parts by mass or less, relative to 100 parts by mass of the total of all polymers contained in the liquid crystal aligning agent.

[0034] The content of the solvent in the liquid crystal aligning agent can be appropriately selected from the viewpoint of the coating method and obtaining the desired thickness of the liquid crystal alignment film. In particular, from the viewpoint of forming a uniform liquid crystal alignment film by coating, the content of the solvent in the liquid crystal aligning agent is preferably 50 to 99.9 mass %, more preferably 60 to 99 mass %, and particularly preferably 65 to 99 mass %. The solvent used for the liquid crystal alignment agent is not particularly limited as long as it is a solvent that can dissolve the specific polymer. Among them, the following solvents (hereinafter also referred to as "Solvent A") are preferably used. For example, N,N-dimethylformamide, N,N-dimethylacetamide, N,N-dimethyllactamide, N,N-dimethylpropionamide, tetramethylurea, N,N-diethylformamide, 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-dimethylpropanamide, methyl ethyl ketone ... Examples of suitable solvents include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-butoxy-N,N-dimethylpropanamide, N-(n-propyl)-2-pyrrolidone, N-isopropyl-2-pyrrolidone, N-(n-butyl)-2-pyrrolidone, N-(tert-butyl)-2-pyrrolidone, N-(n-pentyl)-2-pyrrolidone, N-methoxypropyl-2-pyrrolidone, N-ethoxyethyl-2-pyrrolidone, N-methoxybutyl-2-pyrrolidone, and N-cyclohexyl-2-pyrrolidone (collectively referred to as "good solvents"). Among these, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, and γ-butyrolactone are preferred. These solvents may be used alone or in combination of two or more.

[0035] When the specific polymer has high solubility in the solvent, the following solvent (hereinafter also referred to as "Solvent B") can be used. 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-dibutoxyethane, 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 monomethyl 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 monopropyl ether, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, 2-(2-ethoxyethoxy)ethyl acetate, diethylene glycol Examples of suitable lactic acid bacteria include glycerin, glycerin, propylene glycol diacetate, n-butyl acetate, propylene glycol monoethyl ether acetate, cyclohexyl acetate, 4-methyl-2-pentyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, butyl 3-methoxypropionate, n-butyl lactate, isoamyl lactate, diethylene glycol monoethyl ether, and diisobutyl ketone (2,6-dimethyl-4-heptanone).Among these, diisobutyl carbinol, propylene glycol monobutyl ether, propylene glycol diacetate, diethylene glycol diethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether acetate, or diisobutyl ketone are preferably used. These may be used alone or in combination of two or more.

[0036] In the present invention, from the viewpoint of the coating properties of the liquid crystal alignment film, it is preferable to use a solvent that is a combination of Solvent A and Solvent B. Specifically, 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-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone, N-ethyl-2-pyrrolidone and propylene glycol diacetate, N,N-diphenyl ether, N-methyl-2-pyrrolidone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolact ...methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone and γ-butyrolact Methyl lactamide and diisobutyl ketone, N-methyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-ethyl-2-pyrrolidone and ethyl 3-ethoxypropionate, N-methyl-2-pyrrolidone, ethyl 3-ethoxypropionate and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, ethyl 3-ethoxypropionate and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, ethyl 3-ethoxypropionate and diethylene glycol monopropyl ether, N N-Ethyl-2-pyrrolidone, ethyl 3-ethoxypropionate, and diethylene glycol monopropyl ether, N-methyl-2-pyrrolidone and ethylene glycol monobutyl ether acetate, N-ethyl-2-pyrrolidone and dipropylene glycol dimethyl ether, N,N-dimethyl lactamide and ethylene glycol monobutyl ether, N,N-dimethyl lactamide and propylene glycol diacetate, N-ethyl-2-pyrrolidone and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone N-methyl-2-pyrrolidone, diethylene glycol monomethyl ether, and butyl cellosolve acetate, N-methyl-2-pyrrolidone, diethylene glycol monomethyl ether, and butyl cellosolve acetate, N,N-dimethyl lactamide and diethylene glycol diethyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, 4-hydroxy-4-methyl-2-pentanone, and diethylene glycol diethyl ether, N-ethyl-2-pyrrolidone, N-methyl-2-pyrrolidone, and 4-hydroxy-4-methyl-2-pentanone,N-Ethyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and diisobutyl ketone, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and propylene glycol monobutyl ether, N-methyl-2-pyrrolidone, 4-hydroxy-4-methyl-2-pentanone, and dipropylene glycol monomethyl ether Methyl-2-pentanone and propylene glycol diacetate, N-ethyl-2-pyrrolidone and 4-hydroxy-4-methyl-2-pentanone and dipropylene glycol dimethyl ether, γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and diisobutyl ketone, γ-butyrolactone and 4-hydroxy-4-methyl-2-pentanone and propylene glycol diacetate, N-methyl-2-pyrrolidone and γ-butyrolactone and propylene glycol monobutyl ether and diisobutyl ketone, N-methyl-2-pyrrolidone rolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisopropyl ether, N-methyl-2-pyrrolidone, γ-butyrolactone, propylene glycol monobutyl ether, and diisobutylcarbinol, N-methyl-2-pyrrolidone, γ-butyrolactone, and dipropylene glycol dimethyl ether, N-methyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and dipropylene glycol pyrene glycol monomethyl ether, N-ethyl-2-pyrrolidone, diethylene glycol diethyl ether, and dipropylene glycol monomethyl ether, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and propylene glycol diacetate, N-ethyl-2-pyrrolidone, propylene glycol monobutyl ether, and diisobutyl ketone, N-ethyl-2-pyrrolidone, γ-butyrolactone, and diisobutyl ketone, N-ethyl-2-pyrrolidone, N,N-dimethyl lactamide, and diisobutyl ketone,Examples of the combination include N-methyl-2-pyrrolidone, ethylene glycol monobutyl ether, and ethylene glycol monobutyl ether acetate, γ-butyrolactone, ethylene glycol monobutyl ether acetate, and dipropylene glycol dimethyl ether, N-ethyl-2-pyrrolidone, ethylene glycol monobutyl ether acetate, and propylene glycol dimethyl ether, N-methyl-2-pyrrolidone, 4-methyl-2-pentyl acetate, and ethylene glycol monobutyl ether, N-ethyl-2-pyrrolidone, cyclohexyl acetate, and 4-hydroxy-4-methyl-2-pentanone, cyclohexanone, and propylene glycol monomethyl ether, cyclopentanone, and propylene glycol monomethyl ether, and N-methyl-2-pyrrolidone, cyclohexanone, and propylene glycol monomethyl ether. These combinations are preferred. When solvent A and solvent B are used in combination, solvent B preferably accounts for 1 to 80 mass % of the total solvent contained in the liquid crystal aligning agent, more preferably 10 to 80 mass %, and most preferably 20 to 70 mass %.

[0037] In order to increase the film strength of the liquid crystal alignment film, the liquid crystal aligning agent preferably contains a compound having at least one selected from an epoxy group, an isocyanate group, an oxetane group, a cyclocarbonate group, a hydroxy group, a hydroxyalkyl group, and a lower alkoxyalkyl group (collectively referred to as a crosslinkable compound). In this case, the compound must contain two or more of these groups. Specific examples of crosslinkable compounds having an epoxy group or an isocyanate group include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, and bisphenol A esters such as Epikote 828 (manufactured by Mitsubishi Chemical Corporation). epoxy resins, bisphenol F-type epoxy resins such as Epikote 807 (manufactured by Mitsubishi Chemical Corporation), hydrogenated bisphenol A-type epoxy resins such as YX-8000 (manufactured by Mitsubishi Chemical Corporation), biphenyl skeleton-containing epoxy resins such as YX6954BH30 (manufactured by Mitsubishi Chemical Corporation), phenol novolac-type epoxy resins such as EPPN-201 (manufactured by Nippon Kayaku Co., Ltd.), (o, m, p-)cresol novolac-type epoxy resins such as EOCN-102S (manufactured by Nippon Kayaku Co., Ltd.), tetrakis(glycidyloxymethyl)methane, N,N,N',N'-tetraglycidyl-1,4-phenylenediamine, N,N,N',N'-tetraglycidyl-2,2'-dimethyl-4-Compounds in which a tertiary nitrogen atom is bonded to an aromatic carbon atom, such as 4'-diaminobiphenyl, 2,2-bis[4-(N,N-diglycidyl-4-aminophenoxy)phenyl]propane, and N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane; N,N,N',N'-tetraglycidyl-1,2-diaminocyclohexane, N,N,N',N'-tetraglycidyl-1,3-diaminocyclohexane, N,N,N',N'-tetraglycidyl-1,4-diaminocyclohexane, bis(N,N-diglycidyl-4-aminocyclohexyl)methane, bis(N,N-diglycidyl-2-methyl-4-aminocyclohexyl)methane, bis(N,N-diglycidyl-3-methyl-4-aminocyclohexyl)methane, and 1,3-bis(N Examples of suitable tertiary nitrogen compounds include compounds in which a tertiary nitrogen atom is bonded to an aliphatic carbon atom, such as 1,4-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,4-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,3-bis(N,N-diglycidylaminomethyl)benzene, 1,4-bis(N,N-diglycidylaminomethyl)benzene, 1,3,5-tris(N,N-diglycidylaminomethyl)cyclohexane, and 1,3,5-tris(N,N-diglycidylaminomethyl)benzene; isocyanurate compounds such as triglycidyl isocyanurate, such as TEPIC (manufactured by Nissan Chemical Industries, Ltd.); and those described in paragraph

[0037] of Japanese Patent Publication No. 10-338880 and paragraphs

[0051] to

[0054] of International Publication WO2017 / 170483.

[0038] Specific examples of crosslinkable compounds having an oxetanyl group include 1,4-bis{[(3-ethyl-3-oxetanyl)methoxy]methyl}benzene (Aronoxetane OXT-121 (XDO)), bis[2-(3-oxetanyl)butyl]ether (Aronoxetane OXT-221 (DOX)), 1,4-bis[(3-ethyloxetan-3-yl)methoxy]benzene (HQOX), 1,3-bis[(3-ethyloxetan-3-yl)methoxy]benzene (RSOX), 1,2-bis[(3-ethyloxetan-3-yl)methoxy]benzene (CTOX), and those described in paragraphs

[0170] to

[0175] of International Publication WO2011 / 132751.

[0039] Specific examples of crosslinkable compounds having an oxazoline group include compounds such as 2,2'-bis(2-oxazoline) and 2,2'-bis(4-methyl-2-oxazoline), polymers and oligomers having an oxazoline group such as EPOCROS (manufactured by Nippon Shokubai Co., Ltd.), and those described in paragraph

[0115] of Japanese Patent Publication No. 2007-286597. Specific examples of crosslinkable compounds having a cyclocarbonate group include N,N,N',N'-tetra[(2-oxo-1,3-dioxolan-4-yl)methyl]-4,4'-diaminodiphenylmethane, N,N'-di[(2-oxo-1,3-dioxolan-4-yl)methyl]-1,3-phenylenediamine, and those described in paragraphs

[0025] to

[0030] and

[0032] of International Publication WO2011 / 155577. Specific examples of crosslinkable compounds having a blocked isocyanate group include Coronate AP Stable M, Coronate 2503, 2515, 2507, 2513, 2555, and Millionate MS-50 (all manufactured by Tosoh Corporation), Takenate B-830, B-815N, B-820NSU, B-842N, B-846N, B-870N, B-874N, and B-882N (all manufactured by Mitsui Chemicals, Inc.), and those described in paragraphs

[0046] to

[0047] of Japanese Patent Publication No. 2014-224978 and paragraphs

[0119] to

[0120] of International Publication No. WO2015 / 141598.

[0040] Specific examples of crosslinkable compounds having a hydroxy group and an alkoxy group include N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide, 2,2-bis(4-hydroxy-3,5-dihydroxymethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethoxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dihydroxymethylphenyl)-1,1,1,3,3,3-hexafluoropropane, and those described in paragraph

[0058] of Japanese Patent Publication No. 2016-118753, paragraph

[0055] of Japanese Patent Publication No. 2016-200798, and paragraphs

[0017] to

[0029] of International Publication No. WO2010 / 074269.

[0041] Specific examples of crosslinkable compounds having a polymerizable unsaturated group include glycerin mono(meth)acrylate, glycerin di(meth)acrylate (1,2-, 1,3-mixture), glycerin tris(meth)acrylate, glycerol 1,3-diglycerolate di(meth)acrylate, pentaerythritol tri(meth)acrylate, diethylene glycol mono(meth)acrylate, triethylene glycol mono(meth)acrylate, tetraethylene glycol mono(meth)acrylate, pentaethylene glycol mono(meth)acrylate, and hexaethylene glycol mono(meth)acrylate. The proportion of the crosslinkable compound in the liquid crystal aligning agent is preferably 0.1 to 100 parts by mass relative to 100 parts by mass of all polymer components. From the viewpoint of promoting the crosslinking reaction and achieving the desired effect, it is more preferably 0.1 to 50 parts by mass. It is particularly preferably 1 to 30 parts by mass.

[0042] The liquid crystal aligning agent may be a compound that promotes imidization of a specific polymer. Specifically, compounds for promoting imidization represented by formulas [B-1] to [B-17] described on pages 48 and 49 of International Publication WO2022 / 176680 (published August 25, 2022) are preferred. The amount of the compound used is preferably 0.1 to 20 parts by mass, more preferably 1 to 20 parts by mass, and particularly preferably 5 to 15 parts by mass, based on 100 parts by mass of all polymer components.

[0043] The liquid crystal aligning agent may be a compound that improves the uniformity of the film thickness and the surface smoothness of the liquid crystal alignment film, or a compound that improves the adhesion between the liquid crystal alignment film and the substrate. Compounds that improve the uniformity of the film thickness and surface smoothness of the liquid crystal alignment film include fluorine-based surfactants, silicone-based surfactants, and nonionic surfactants. Specific examples include the surfactants described on page 67 of International Publication WO2014 / 171493 (published October 23, 2014). The amount of such surfactants used is preferably 0.01 to 2 parts by mass, more preferably 0.01 to 1 part by mass, per 100 parts by mass of all polymer components.

[0044] Specific examples of compounds that enhance adhesion between a liquid crystal alignment film and a substrate include the compounds described on pages 67 to 69 of International Publication WO2014 / 171493 (published October 23, 2014). More specifically, these compounds 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, vinyltrimethoxysilane, vinyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropylmethyldimethoxysilane. Examples of suitable silanes include 3-acryloxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, tris[3-(trimethoxysilyl)propyl]isocyanurate, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane. The preferred proportion of the silanes used is 0.1 to 30 parts by mass, more preferably 1 to 20 parts by mass, per 100 parts by mass of all polymer components. In addition to the compounds other than those mentioned above, the liquid crystal aligning agent may contain a dielectric or conductive substance for the purpose of changing the electrical properties such as the dielectric constant and conductivity of the liquid crystal alignment film.

[0045] <Liquid crystal alignment film / LCD element> The liquid crystal display element can be manufactured by, for example, a method including the following steps (1) to (3), a method including steps (1) to (4), a method including steps (1) to (3), (3b) and (4), a method including steps (1) to (2) and (4), a method including steps (1) to (3), (4) and (5), or a method including steps (1) to (3), (4) and (6).

[0046] "Step (1): Step of applying a liquid crystal alignment agent to at least one of the first substrate and the second substrate" Step (1) is a step of applying a liquid crystal alignment agent onto a substrate, specifically as follows. That is, a liquid crystal alignment agent is applied to one surface of a substrate provided with a patterned transparent conductive film by a coating method such as a roll coater method, a spin coat method, a printing method, or an inkjet method. The substrate is not particularly limited as long as it is a highly transparent substrate, and plastic substrates such as acrylic substrates and polycarbonate substrates can be used in addition to glass substrates and silicon nitride substrates. In addition, in a reflective liquid crystal display element, an opaque substrate such as a silicon wafer can be used as the substrate on only one side, and in this case, a light-reflecting material such as aluminum can be used for the electrode.

[0047] When manufacturing an IPS or FFS driving liquid crystal display element, a substrate having an electrode made of a transparent conductive film or a metal film patterned into a comb-tooth shape and an opposing substrate having no electrode are used. The transparent conductive film is formed by a known method using indium tin oxide (ITO), indium zinc oxide (IZO), or a mixture thereof. The method for applying the liquid crystal aligning agent to the substrate includes screen printing, offset printing, flexographic printing, ink jet method, spray method, etc. Among these, the ink jet method is preferred in the present invention.

[0048] "Step (2): Step of baking the applied liquid crystal alignment agent" Step (2) is a step of forming a liquid crystal alignment film by baking the liquid crystal alignment agent applied to the substrate. Specifically, the process is as follows. That is, after applying the liquid crystal alignment agent to the substrate in step (1), the solvent is evaporated and the polyamic acid or polyamic acid ester is thermally imidized by baking using a heating means such as a hot plate, a heat circulation oven, or an IR (infrared) oven (this treatment is also referred to as the baking step). The temperature and time of the baking step can be selected arbitrarily, and the baking step may be repeated multiple times. The baking step temperature is preferably 30 to 230°C, more preferably 30 to 200°C. To reduce the residual solvent in the liquid crystal alignment film, the baking temperature may be 40 to 150°C or 40 to 120°C. The baking time is not particularly limited, but may be 1 to 10 minutes or 1 to 5 minutes.

[0049] When thermally imidizing a polyimide precursor such as polyamic acid or polyamic acid ester, an additional baking step (this treatment is also referred to as a main baking step) may be performed after the baking step. The temperature at this time is preferably, for example, 150 to 300°C or 150 to 250°C. The baking time in the main baking step is not particularly limited, but may be 5 to 40 minutes or 5 to 30 minutes. The main baking step may not be performed in step (2), and the main baking step or step (3b) may be performed after the following step (3). The thickness of the liquid crystal alignment film after baking is preferably 5 to 300 nm, more preferably 10 to 200 nm, because if it is too thick, it will be disadvantageous in terms of power consumption of the liquid crystal display element, and if it is too thin, the reliability of the element may decrease.

[0050] "Step (3): A step of performing an alignment treatment on the liquid crystal alignment film obtained in step (2)" Step (3) is a step of performing an alignment treatment on the liquid crystal alignment film obtained in step (2). In a lateral electric field driving type liquid crystal display element such as an IPS driving type or an FFS driving type, as described above, an alignment treatment such as a rubbing treatment or a photo-alignment treatment is performed on the liquid crystal alignment film to align the liquid crystal horizontally. In the present invention, a photo-alignment treatment is preferred. In contrast, a vertical electric field driving type liquid crystal display element such as a VA (Vertical Alignment) driving type or a PSA (Polymer Sustained Alignment) driving type does not require an alignment treatment. The rubbing treatment is a treatment in which the liquid crystal alignment film is rubbed in a certain direction with a roll wrapped with a cloth made of fibers such as nylon, rayon, or cotton.

[0051] Examples of photo-alignment treatment include a method in which the surface of a liquid crystal alignment film is irradiated with polarized radiation in a certain direction to regulate the alignment of the liquid crystals (also referred to as imparting liquid crystal alignment properties or liquid crystal alignment ability). The radiation may be ultraviolet light or visible light having a wavelength of 100 to 800 nm. Of these, ultraviolet light having a wavelength of 100 to 400 nm is preferred. More preferred is ultraviolet light having a wavelength of 200 to 400 nm. The radiation dose is 1 to 10,000 mJ / cm. 2 More preferably, it is 100 to 1,000 mJ / cm. 2 Particularly preferred is 100 to 500 mJ / cm 2 Furthermore, when the radiation is polarized, it may be linearly polarized or partially polarized. When the radiation is linearly polarized or partially polarized, it may be irradiated from a direction perpendicular to the liquid crystal alignment film surface, from an oblique direction, or a combination of these. When irradiating with unpolarized radiation, it is preferable that the irradiation direction is oblique to the liquid crystal alignment film surface. When irradiating with radiation, in order to increase the stability of the liquid crystal alignment, it is preferable to irradiate while heating the liquid crystal alignment film-attached substrate at 50 to 250° C. This allows the liquid crystal to be stably aligned in a certain direction.

[0052] "Step (3b): Step of performing heat treatment" The liquid crystal alignment film irradiated with radiation in step (3) can be subjected to a heat treatment. The temperature at which this is done is preferably 50 to 250° C., more preferably 120 to 230° C. The time is preferably 1 to 30 minutes. "Step (4): A step of disposing a liquid crystal layer between the first substrate and the second substrate so as to be adjacent to the alignment-treated liquid crystal alignment film, thereby producing a liquid crystal cell (liquid crystal display element)." In step (4), a liquid crystal layer is disposed between the first and second substrates so as to be adjacent to the alignment-treated liquid crystal alignment film, thereby preparing a liquid crystal cell. The following illustrates an example in which a liquid crystal alignment film is formed on each of the first and second substrates. In the first method, two substrates are placed opposite each other with a gap (also called a cell gap) between them so that their liquid crystal alignment films face each other. Next, the peripheries of the two substrates are bonded together with a sealant, and a liquid crystal composition is injected into the substrate surfaces and the cell gap defined by the sealant. After the liquid crystal composition contacts the liquid crystal alignment film surface, the injection hole is sealed. The second method is called the ODF (One Drop Fill) method. For example, a UV-curable resin composition (hereinafter also referred to as a "sealant") is applied to a predetermined location on one of two substrates on which a liquid crystal alignment film has been formed, and a liquid crystal composition is then dropped onto several predetermined locations on the liquid crystal alignment film surface. The other substrate is then attached so that the liquid crystal alignment film faces the other substrate, and the liquid crystal composition is spread over the entire surface of the substrate and brought into contact with the film surface. Next, the entire surface of the substrate is irradiated with UV light to cure the sealant.

[0053] In both the first and second methods, it is desirable to heat the liquid crystal composition used to a temperature at which it assumes an isotropic phase, and then slowly cool it to room temperature to remove flow alignment that occurs when the liquid crystal composition is filled. When the rubbing treatment is performed, the two substrates are arranged to face each other so that the rubbing directions of the liquid crystal alignment films are at a predetermined angle, for example, perpendicular or anti-parallel to each other. The sealing agent may be an epoxy resin containing a hardener and aluminum oxide spheres as spacers. The liquid crystal composition is not particularly limited, and any liquid crystal composition containing at least one liquid crystal compound (liquid crystal molecule) and having a positive or negative dielectric anisotropy can be used. In the following, a liquid crystal composition having a positive dielectric anisotropy will also be referred to as a positive liquid crystal, and a liquid crystal composition having a negative dielectric anisotropy will also be referred to as a negative liquid crystal.

[0054] The liquid crystal composition may contain a liquid crystal compound having a fluorine atom, a hydroxy group, an amino group, a fluorine atom-containing group (e.g., a trifluoromethyl group), a cyano group, an alkyl group, an alkoxy group, an alkenyl group, an isothiocyanate group, a heterocycle, a cycloalkane, a cycloalkene, a steroid skeleton, a benzene ring, or a naphthalene ring, or may contain a compound having two or more rigid moieties (mesogenic skeletons) that exhibit liquid crystallinity within the molecule (e.g., a bimesogenic compound in which two rigid biphenyl structures or terphenyl structures are linked by an alkylene group). The liquid crystal composition may be a liquid crystal composition exhibiting a nematic phase, a liquid crystal composition exhibiting a smectic phase, or a liquid crystal composition exhibiting a cholesteric phase. The liquid crystal composition may contain additives to enhance the liquid crystal alignment property, such as photopolymerizable monomers having a polymerizable group, optically active compounds (e.g., S-811 manufactured by Merck Ltd.), antioxidants, ultraviolet absorbers, dyes, antifoaming agents, polymerization initiators, or polymerization inhibitors.

[0055] Examples of positive liquid crystals include ZLI-2293, ZLI-4792, MLC-2003, MLC-2041, MLC-3019, and MLC-7081 manufactured by Merck Co., Ltd.; and PA-1492 manufactured by DIC Corporation. Examples of negative liquid crystals include MLC-6608, MLC-6609, MLC-6610, and MLC-7026-100 manufactured by Merck. An example of a liquid crystal containing a compound having a polymerizable group is MLC-3023 manufactured by Merck.

[0056] The liquid crystal aligning agent can also be used in a liquid crystal display element (PSA-type liquid crystal display element) manufactured through a step (hereinafter, this step may also be referred to as "step (5)") of having a liquid crystal layer between a pair of substrates equipped with electrodes, and disposing a liquid crystal composition containing a polymerizable compound that is polymerized by at least one of active energy rays and heat between the pair of substrates, and polymerizing the polymerizable compound by at least one of irradiation with active energy rays and heating while applying a voltage between the electrodes. The liquid crystal alignment agent can also be used in a liquid crystal display element (SC-PVA type liquid crystal display element) manufactured through a process of having a liquid crystal layer between a pair of substrates equipped with electrodes, disposing a liquid crystal alignment film between the pair of substrates and containing a polymerizable group that polymerizes by at least one of active energy rays and heat, and applying a voltage between the electrodes (hereinafter, this process will also be referred to as "process (6)"). If necessary, a polarizing plate can be attached to the outer surface of the liquid crystal cell obtained as described above. Examples of the polarizing plate to be attached to the outer surface of the liquid crystal cell include a polarizing plate in which a polarizing film called an "H film" made by stretching and aligning polyvinyl alcohol and absorbing iodine is sandwiched between cellulose acetate protective films, and an H film polarizing plate.

[0057] An IPS substrate, which is a comb-tooth electrode substrate used in the IPS driving method, has a substrate, a plurality of linear electrodes formed on the substrate and arranged in a comb-tooth pattern, and a liquid crystal alignment film formed on the substrate to cover the linear electrodes. The FFS substrate, which is a comb-tooth electrode substrate used in the FFS method, has a substrate, a surface electrode formed on the substrate, an insulating film formed on the surface electrode, a plurality of linear electrodes formed on the insulating film and arranged in a comb-tooth pattern, and a liquid crystal alignment film formed on the insulating film to cover the linear electrodes.

[0058] FIG. 1 is a schematic cross-sectional view showing an example of a lateral electric field type liquid crystal display element of the present invention, which is an example of an IPS driving type liquid crystal display element. The in-plane switching liquid crystal display element 1 illustrated in FIG. 1 has a liquid crystal 3 sandwiched between a comb-shaped electrode substrate 2 having a liquid crystal alignment film 2c and a counter substrate 4 having a liquid crystal alignment film 4a. The comb-shaped electrode substrate 2 has a substrate 2a, a plurality of linear electrodes 2b arranged in a comb-like pattern on the substrate 2a, and a liquid crystal alignment film 2c formed on the substrate 2a to cover the linear electrodes 2b. The counter substrate 4 has a substrate 4b and a liquid crystal alignment film 4a formed on the substrate 4b. The liquid crystal alignment film 2c is, for example, a liquid crystal alignment film of the present invention. The liquid crystal alignment film 4a is also a liquid crystal alignment film of the present invention. In this in-plane switching liquid crystal display element 1, when a voltage is applied to the linear electrodes 2b, an electric field is generated between the linear electrodes 2b, as indicated by electric field lines L.

[0059] FIG. 2 is a schematic cross-sectional view showing another example of a liquid crystal display element of the in-plane switching type, which is an example of a liquid crystal display element of the FFS driving system. The in-plane switching liquid crystal display element 1 illustrated in FIG. 2 has a liquid crystal 3 sandwiched between a comb-shaped electrode substrate 2 having a liquid crystal alignment film 2h and a counter substrate 4 having a liquid crystal alignment film 4a. The comb-shaped electrode substrate 2 includes a substrate 2d, a surface electrode 2e formed on the substrate 2d, an insulating film 2f formed on the surface electrode 2e, a plurality of linear electrodes 2g formed on the insulating film 2f and arranged in a comb-like pattern, and a liquid crystal alignment film 2h formed on the insulating film 2f to cover the linear electrodes 2g. The counter substrate 4 includes a substrate 4b and a liquid crystal alignment film 4a formed on the substrate 4b. The liquid crystal alignment film 2h is, for example, a liquid crystal alignment film of the present invention. The liquid crystal alignment film 4a is also a liquid crystal alignment film of the present invention. When a voltage is applied to the surface electrodes 2e and the linear electrodes 2g in this in-plane switching liquid crystal display element 1, an electric field is generated between the surface electrodes 2e and the linear electrodes 2g, as indicated by electric field lines L. The liquid crystal display element of the present invention can be effectively applied to various devices, such as displays for clocks, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, mobile phones, smartphones, various monitors, liquid crystal televisions, and information displays.

[0060] The liquid crystal alignment film of the present invention can be used for applications other than those mentioned above. For example, it can be used as a liquid crystal alignment film for a retardation film, a liquid crystal alignment film for a scanning antenna or a liquid crystal array antenna, or a liquid crystal alignment film for a transmissive / scattering liquid crystal dimming element. Furthermore, it can be used for applications other than liquid crystal alignment films, such as a protective film (e.g., a protective film for a color filter), a spacer film, an interlayer insulating film, an antireflection film, a wiring covering film, an antistatic film, and an insulating film for an electric motor (e.g., a gate insulating film for a flexible display). [Example]

[0061] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. The abbreviations used in the examples and comparative examples and the methods for measuring the various physical properties are as follows. <Solvent> NMP: N-methyl-2-pyrrolidone γ-BL: γ-butyrolactone BCS: Ethylene glycol monobutyl ether <Tetracarboxylic acid dianhydride> A1 to A4: Tetracarboxylic acid dianhydrides represented by the following formulae [A1] to [A4] [ka]

[0062] <Diamine> B1 to B8: Diamines of the following formulae [B1] to [B8] [ka]

[0063] <Specific compound> C1 to C7: Compounds of the following formulae [C1] to [C7] [ka]

[0064] <Additives> K1: A compound of the following formula [K1] K2: N-α-(9-fluorenylmethoxycarbonyl)-N-τ-(tert-butoxycarbonyl)-L-histidine K3: 3-glycidoxypropylmethyldiethoxysilane [ka]

[0065] "Viscosity measurement" Measurements were performed using an E-type viscometer TVE-22H (manufactured by Toki Sangyo Co., Ltd.) at a temperature of 25°C, a sample volume of 1.1 mL, and a cone rotor TE-1 (1°34', R24). "Gardner color number" Measurements were made using a simultaneous spectroscopic colorimeter and turbidity analyzer TZ7700 (manufactured by Nippon Denshoku Industries Co., Ltd.).

[0066] "Synthesis of polyimide polymers" <Synthesis Example 1> B1 (2.16 g, 20.0 mmol), B2 (7.33 g, 30.0 mmol), B4 (9.61 g, 30.0 mmol), B6 ​​(7.97 g, 20.0 mmol), and NMP (311.3 g) were added to a 500 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was dissolved by stirring at 25 °C while supplying nitrogen. Then, A2 (20.9 g, 93.0 mmol) and NMP (40.1 g) were added and the mixture was stirred at 40 °C for 24 hours to obtain a polyamic acid solution (1) with a solids concentration of 12 wt% (viscosity: 405 mPa s).

[0067] <Synthesis Example 2> B7 (6.38 g, 32.0 mmol), B8 (1.22 g, 8.00 mmol), and NMP (110.1 g) were added to a 200 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was dissolved by stirring at 25°C while supplying nitrogen. Subsequently, A4 (11.2 g, 38.0 mmol) and NMP (27.5 g) were added and the mixture was stirred at 25°C for 24 hours to obtain a polyamic acid solution (2) with a solids concentration of 12% by mass (viscosity: 398 mPa s).

[0068] <Synthesis Example 3> B3 (2.29 g, 8.00 mmol) and NMP (16.8 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and dissolved by stirring at 25°C while supplying nitrogen. Then, A2 (1.69 g, 7.52 mmol) and NMP (12.4 g) were added, and the mixture was stirred at 40°C for 24 hours to obtain a polyamic acid solution (3) with a solids concentration of 12% by mass (viscosity: 240 mPa s).

[0069] <Synthesis Example 4> B3 (1.50 g, 5.24 mmol), B5 (0.73 g, 1.75 mmol), and NMP (20.1 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was dissolved by stirring at 25°C while supplying nitrogen. Then, A2 (1.47 g, 6.56 mmol) and NMP (6.90 g) were added and the mixture was stirred at 40°C for 24 hours to obtain a polyamic acid solution (4) with a solids concentration of 12% by mass (viscosity: 236 mPa s).

[0070] <Synthesis Example 5> B1 (0.30 g, 2.80 mmol), B7 (2.33 g, 11.2 mmol), and NMP (39.7 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was dissolved by stirring at 25°C while supplying nitrogen. Then, A3 (2.65 g, 13.5 mmol) and NMP (6.90 g) were added and the mixture was stirred at 25°C for 24 hours to obtain a polyamic acid solution (5) with a solids concentration of 10% by mass (viscosity: 238 mPa s).

[0071] <Synthesis Example 6> B2 (1.95 g, 8.00 mmol), B7 (1.59 g, 8.00 mmol), and NMP (31.9 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was dissolved by stirring at 25 °C while supplying nitrogen. Subsequently, A1 (3.00 g, 12.0 mmol) and NMP (5.20 g) were added and the mixture was stirred at 50 °C for 4 hours. Subsequently, A4 (0.94 g, 3.20 mmol) and NMP (5.30 g) were added and the mixture was stirred at 70 °C for 12 hours to obtain a polyamic acid solution (6) with a solids concentration of 15% by mass (viscosity: 298 mPa s).

[0072] <Synthesis Example 7> B7 (2.07 g, 10.4 mmol), B8 (0.40 g, 2.60 mmol), and NMP (22.2 g) were added to a 50 mL four-neck flask equipped with a stirrer and a nitrogen inlet tube, and the mixture was dissolved by stirring at 25 °C while supplying nitrogen. Subsequently, A1 (0.81 g, 3.25 mmol) and NMP (1.90 g) were added and the mixture was stirred at 50 °C for 4 hours. Subsequently, A4 (2.68 g, 9.10 mmol) and NMP (19.6 g) were added and the mixture was stirred at 70 °C for 12 hours to obtain a polyamic acid solution (7) with a solids concentration of 12% by mass (viscosity: 298 mPa s). The specifications of the polyimide polymer obtained above are shown in Table 1.

[0073] [Table 1]

[0074] "Production of liquid crystal alignment agent" Examples of producing liquid crystal aligning agents will be described in the following Examples 1 to 14 and Comparative Examples 1 to 4. These liquid crystal aligning agents are also used for evaluation purposes. The liquid crystal alignment agents are shown in Table 2. Example 1 Polyamic acid solution (1) (4.33 g) obtained by the method of Synthesis Example 1, polyamic acid solution (2) (4.33 g) obtained by the method of Synthesis Example 2, C1 (0.052 g), 10 mass% NMP solution of K1 (0.52 g), 3 mass% NMP solution of K2 (0.083 g), 3 mass% NMP solution of K3 (0.35 g), NMP (4.33 g) and BCS (6.00 g) were added and stirred at 25 ° C for 30 minutes to obtain a liquid crystal aligning agent (1). No abnormalities such as turbidity or precipitation were observed in this liquid crystal aligning agent, and it was confirmed to be a homogeneous solution. Using the obtained liquid crystal aligning agent (1), "Evaluation of storage stability of liquid crystal aligning agent" was performed.

[0075] <Examples 2 to 4> As shown in Table 2, liquid crystal aligning agents (2) to (4) were obtained by the same method as in Example 1, except that the type of component (B) (specific compound) used was changed. These liquid crystal aligning agents did not show any abnormalities such as turbidity or the occurrence of precipitates, and were confirmed to be homogeneous solutions. Using the obtained liquid crystal aligning agents, "evaluation of storage stability of liquid crystal aligning agents" was performed.

[0076] <Example 5> Polyamic acid solution (1) (3.60 g) obtained by the method of Synthesis Example 1, polyamic acid solution (5) (6.48 g) obtained by the method of Synthesis Example 5, C1 (0.054 g), 10 mass% NMP solution of K1 (0.54 g), 3 mass% NMP solution of K3 (0.36 g), NMP (3.02 g) and BCS (6.00 g) were added and stirred at 25 ° C for 30 minutes to obtain liquid crystal aligning agent (5). This liquid crystal aligning agent did not show any abnormalities such as turbidity or precipitation, and it was confirmed to be a homogeneous solution. Using the obtained liquid crystal aligning agent (5), "Evaluation of storage stability of liquid crystal aligning agent" was performed.

[0077] Example 6 Polyamic acid solution (3) (1.63 g) obtained by the method of Synthesis Example 3, polyamic acid solution (6) (3.90 g) obtained by the method of Synthesis Example 6, C1 (0.0078 g), 10 mass% NMP solution of K1 (0.39 g), 3 mass% NMP solution of K2 (0.78 g), NMP (0.90 g), γ-BL (6.39 g) and BCS (6.00 g) were added and stirred at 25 ° C for 30 minutes to obtain liquid crystal aligning agent (6). No abnormalities such as turbidity or precipitation were observed in this liquid crystal aligning agent, and it was confirmed that it was a homogeneous solution. Using the obtained liquid crystal aligning agent (6), "Evaluation of storage stability of liquid crystal aligning agent" was performed.

[0078] <Examples 7 to 13> As shown in Table 2, liquid crystal aligning agents (7) to (13) were obtained in the same manner as in Example 6, except that the type and blending ratio of the (B) component (specific compound) used were changed. These liquid crystal aligning agents did not show any abnormalities such as turbidity or the generation of precipitates, and were confirmed to be homogeneous solutions. Using the obtained liquid crystal aligning agents, "evaluation of storage stability of liquid crystal aligning agents" was performed.

[0079] Example 14 Polyamic acid solution (4) (2.21 g) obtained by the method of Synthesis Example 4, polyamic acid solution (7) (6.63 g) obtained by the method of Synthesis Example 7, C1 (0.053 g), 10 mass% NMP solution of K1 (0.53 g), 3 mass% NMP solution of K2 (0.35 g), NMP (4.23 g) and BCS (6.00 g) were added and stirred at 25 ° C for 30 minutes to obtain liquid crystal aligning agent (14). This liquid crystal aligning agent did not show any abnormalities such as turbidity or precipitation, and it was confirmed to be a homogeneous solution. Using the obtained liquid crystal aligning agent (14), "Evaluation of storage stability of liquid crystal aligning agent" was performed.

[0080] <Comparative Example 1> As shown in Table 2, a liquid crystal aligning agent (15) was obtained by the same method as in Example 1, except that the component (B) (specific compound) was not used. This liquid crystal aligning agent did not show any abnormalities such as turbidity or the generation of precipitates, and it was confirmed to be a uniform solution. Using the obtained liquid crystal aligning agent, "evaluation of storage stability of liquid crystal aligning agent" was performed.

[0081] <Comparative Example 2> As shown in Table 2, a liquid crystal aligning agent (16) was obtained by the same method as in Example 5, except that the component (B) (specific compound) was not used. This liquid crystal aligning agent did not show any abnormalities such as turbidity or the generation of precipitates, and it was confirmed to be a uniform solution. Using the obtained liquid crystal aligning agent, "evaluation of storage stability of liquid crystal aligning agent" was performed.

[0082] <Comparative Example 3> As shown in Table 2, a liquid crystal aligning agent (17) was obtained by the same method as in Example 6, except that the component (B) (specific compound) was not used. This liquid crystal aligning agent did not show any abnormalities such as turbidity or the generation of precipitates, and it was confirmed to be a uniform solution. Using the obtained liquid crystal aligning agent, "evaluation of storage stability of liquid crystal aligning agent" was performed.

[0083] <Comparative Example 4> As shown in Table 2, a liquid crystal aligning agent (18) was obtained by carrying out the same procedure as in Example 14, except that the component (B) (specific compound) was not used. This liquid crystal aligning agent did not show any abnormalities such as turbidity or the generation of precipitates, and it was confirmed to be a uniform solution. Using the obtained liquid crystal aligning agent, "evaluation of storage stability of liquid crystal aligning agent" was carried out.

[0084] The specifications of the liquid crystal alignment agent are shown in Table 2. The values ​​in parentheses for component (A) (specific polymer) in Table 2 indicate the blending ratio (parts by mass) of each polymer relative to 100 parts by mass of the total polymer components used in the liquid crystal alignment agent. The numerical values ​​in parentheses for component (B) (specific compound) in Table 2 indicate the blending ratio (parts by mass) of the specific compound relative to 100 parts by mass of the polyimide polymer.

[0085] [Table 2]

[0086] "Evaluation of storage stability of liquid crystal alignment agents" The viscosity and Gardner color index of the liquid crystal alignment agents (1) to (18) prepared above were measured immediately after production and after leaving at room temperature (25°C) for 72 hours. In this evaluation, the smaller the difference (amount of change) between the value immediately after production and the value after leaving, the more excellent the storage stability of the liquid crystal alignment agent. Table 3 shows the evaluation results of the storage stability of the liquid crystal aligning agent.

[0087] [Table 3]

[0088] As can be seen from the above results, the liquid crystal aligning agents of the Examples of the present invention had superior storage stability compared to the liquid crystal aligning agents of the Comparative Examples. In particular, the liquid crystal aligning agents of the Examples showed small changes in viscosity and Gardner color index even after being left at room temperature (25°C) for 72 hours. Specifically, the examples and comparative examples differing only in the presence or absence of a specific compound in the liquid crystal aligning agent were compared, i.e., Examples 1 to 4 and Comparative Example 1, Example 5 and Comparative Example 2, Examples 6 to 13 and Comparative Example 3, and Example 14 and Comparative Example 4. [Industrial Applicability]

[0089] The liquid crystal aligning agent containing the polyimide polymer having a specific structure and the compound having a specific structure of the present invention does not undergo change in viscosity or coloration even when stored at room temperature for a long period of time. As a result, the liquid crystal alignment film prepared using the agent does not suffer from uneven coating film, non-uniform film thickness, or coloration, resulting in a liquid crystal display element with excellent display quality. Therefore, the liquid crystal display element of the present invention is useful as a liquid crystal display element for smartphones, tablet terminals, etc. [Explanation of symbols]

[0090] 1: In-plane switching liquid crystal display element, 2: Comb electrode substrate, 2a: Substrate, 2b: Linear electrode, 2c: Liquid crystal alignment film, 2d: Substrate, 2e: Planar electrode, 2f: Insulating film, 2g: Linear electrode, 2h: Liquid crystal alignment film, 3: Liquid crystal, 4: Counter substrate, 4a: Liquid crystal alignment film, 4b: Substrate, L: Electric field line

Claims

1. A liquid crystal aligning agent comprising the following components (A) and (B): Component (A): At least one polymer selected from a polyimide precursor having a structural unit of the following formula [A1] and a polyimide which is an imide compound of the polyimide precursor. Component (B): At least one compound selected from the following formulas [C1] to [C4]. 【Chemical 1】 (X Ａ represents a tetravalent organic group derived from a tetracarboxylic acid component. Ａ represents a divalent organic group derived from a diamine component. Ａ R each independently represents a hydrogen atom or a monovalent organic group. Ｂ each independently represents a hydrogen atom or a monovalent organic group. 【Chemistry 2】 (Ar represents a monovalent aromatic ring group. The moieties represented by solid and broken lines as follows represent single or double bonds. m represents an integer of 1 to 4. R ｃ represents an alkyl group having 1 or 3 carbon atoms. 【Chemistry 3】

2. Y in the formula [A1] Ａ is expressed by the following formula [Y Ａ −1] and the formula [Y Ａ 2. The liquid crystal aligning agent according to claim 1, wherein the divalent organic group is derived from at least one diamine component selected from the group consisting of: 【Chemistry 4】 (R Ｙ A each independently represents at least one selected from a halogen atom, a hydroxy group, an optionally protected amino group, a thiol group, a nitro group, a phosphate group, and a monovalent organic group having 1 to 20 carbon atoms. Ｙ represents at least one selected from an ester bond, an amide bond, a thioester bond, and a divalent organic group having 2 to 20 carbon atoms. Each a1 independently represents an integer of 0 to 4. a represents an integer of 1 to 4. b and c independently represent an integer of 1 or 2. * represents a bond.

3. 3. The liquid crystal aligning agent according to claim 1, wherein the component (B) is at least one selected from the group consisting of salicylic acid, gallic acid, apigenin, acacetin, chrysin, naringenin, methyl gallate, and propyl gallate.

4. A liquid crystal alignment film obtained from the liquid crystal aligning agent according to claim 1 or 2.

5. A liquid crystal display device comprising the liquid crystal alignment film of claim 4.

6. A method for manufacturing a liquid crystal display element, comprising the following steps (1) to (4): Step (1): A step of applying the liquid crystal aligning agent according to claim 1 or 2 to at least one of the first substrate and the second substrate. Step (2): A step of baking the applied liquid crystal alignment agent to obtain a film. Step (3): A step of subjecting the film obtained in step (2) to an alignment treatment. Step (4): A step of disposing a liquid crystal layer between the first substrate and the second substrate so as to be adjacent to the alignment-treated film, thereby preparing a liquid crystal cell.

7. The method for manufacturing a liquid crystal display element according to claim 6 , wherein the alignment treatment is a photo-alignment treatment.

8. 8. The method for producing a liquid crystal display element according to claim 7, further comprising a step (3b) of carrying out a heat treatment between the steps (3) and (4).

9. 7. The method for manufacturing a liquid crystal display element according to claim 6, wherein the liquid crystal display element is of an IPS drive system or an FFS drive system.

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