Liquid crystal alignment agent, liquid crystal alignment film and liquid crystal device using the same

Abstract

To provide a liquid crystal alignment film capable of forming a liquid crystal display element having favorable afterimage characteristics and excellent display quality, and liquid crystal alignment agent for alignment.SOLUTION: There are provided a liquid crystal alignment agent and liquid crystal alignment film, and a liquid crystal element using the same. The liquid crystal alignment agent contains a polymer (K) which is at least one polymer selected from a group consisting of a polyamic acid, a polyamic acid ester and a polyimide, where a raw material composition of the polymer (K) contains at least one tetracarboxylic acid derivative represented by formula (I) and at least one diamine having a specific structure.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal device using the same. [Background technology]

[0002] Liquid crystal elements are known that can cause optical phenomena such as refraction, scattering, and reflection of electromagnetic waves incident on the element by controlling or modulating the orientation state of the liquid crystal layer within the element.Specific examples of such elements include liquid crystal display elements described below, as well as liquid crystal antennas, light control windows, optical compensation materials, and variable phase shifters.

[0003] Liquid crystal display elements are known to have various driving modes, including twisted nematic (TN) mode, super twisted nematic (STN) mode, in-plane switching (IPS) mode, fringe field switching (FFS) mode, and vertical alignment multi-domain vertical alignment (VA) mode. These liquid crystal display elements are used in image display devices for various electronic devices, such as televisions and mobile phones, and development is ongoing to further improve display quality. Specifically, improvements in the performance of liquid crystal display elements are achieved not only through improvements in driving modes and element structures, but also through the components used in the elements. Among the components used in liquid crystal display elements, liquid crystal alignment films are one of the important materials related to display quality, and active research is being conducted on liquid crystal alignment films to meet the demand for higher quality liquid crystal display elements.

[0004] Patent Document 1 discloses that a liquid crystal alignment film is formed using a polyamic acid having a Boc structure (Boc is a tertiary butoxycarbonyl group), thereby improving the liquid crystal alignment properties. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2023-155156 Summary of the Invention

[0006] In recent years, the applications of liquid crystal display elements have become diverse, including monitors for personal computers, LCD televisions, mobile phones, smartphone displays, and medical monitors. There is a demand for better display quality, and image retention is an important characteristic that affects display quality. To improve image retention in liquid crystal alignment films, it is necessary to obtain a liquid crystal alignment film that exhibits good liquid crystal alignment properties.

[0007] In order to further improve the quality of liquid crystal display elements, the present inventors have conducted research and discovered that by using a polymer containing a diamine having a structure represented by formula (II) instead of a Boc structure, it is possible to obtain a liquid crystal alignment film that exhibits good liquid crystal alignment properties, regardless of whether the liquid crystal alignment film is produced by rubbing treatment or photo-alignment treatment.

[0008] Therefore, the present inventors have conducted extensive research with the objectives of providing a liquid crystal alignment film that can form a liquid crystal display element having good afterimage characteristics and excellent display quality, and of providing a liquid crystal alignment agent for alignment that can form such a liquid crystal alignment film.

[0009] The present invention employs the following means to solve the above problems.

[0010] [1] A liquid crystal aligning agent containing a polymer (K) which is at least one polymer selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, The raw material composition of the polymer (K) is a liquid crystal aligning agent that contains at least one tetracarboxylic acid derivative represented by formula (I) and at least one diamine having a structure represented by formula (II). [ka] In formula (I), *1, *1', *2 and *2' are bonds, each independently bonded to a hydroxyl group, a chlorine atom or an alkoxy group having 1 to 6 carbon atoms, and at least one pair of *1 and *1' and at least one pair of *2 and *2' may be bonded to the same oxygen atom; R b1 , R b2 , R b3 , and R b4 are each independently a hydrogen atom or a methyl group, and at least one is a methyl group. [ka] In formula (II), *3 and *4 are bonds, each independently a bond bonded to a hydrogen atom or a carbon atom (provided that one or both of *3 and *4 are bonds bonded to a carbon atom); A 1 is a monovalent hydrocarbon group having 5 or more carbon atoms, or a monovalent group having 5 or more carbon atoms and having -O- between the carbon-carbon bonds of the hydrocarbon group. [2] In the formula (II), A 1 is a monovalent hydrocarbon group having 5 to 10 carbon atoms, or a monovalent group having 5 to 10 carbon atoms and having -O- between the carbon-carbon bond of the hydrocarbon group. [3] A liquid crystal aligning agent further comprising a polymer (L) which is at least one polymer selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, The liquid crystal aligning agent according to [2], wherein the raw material composition of the polymer (L) does not contain diamines having a structure represented by formula (II). [4] The liquid crystal aligning agent according to [3], wherein the structure represented by formula (II) is a structure represented by formula (III): [ka] In formula (III), *3 and *4 are bonds, each independently a bond bonded to a hydrogen atom or a carbon atom (provided that one or both of *3 and *4 are bonds bonded to a carbon atom); R a1 , Ra2 and R a3 are each independently a monovalent chain hydrocarbon group having 1 to 7 carbon atoms, or a monovalent group having 1 to 7 carbon atoms and having -O- between the carbon-carbon bonds of the chain hydrocarbon group. a1 , R a2 and R a3 The total number of carbon atoms is 4 to 9. [5] The liquid crystal aligning agent according to [4], wherein the compound represented by formula (I) is a compound represented by formula (I-1): [ka] [6] The liquid crystal aligning agent according to [5], wherein the raw material composition of the polymer (K) contains at least one compound represented by formula (DI-4-1), formula (DI-5-1), or formula (DI-13-1). [ka] In formula (DI-5-1), m is 2 or 4. [7] A liquid crystal aligning agent according to any one of [1] to [6], which is used in a photo-alignment type in-plane switching liquid crystal display element. [8] A liquid crystal alignment film formed from the liquid crystal aligning agent according to any one of [1] to [7]. [9] A liquid crystal element having the liquid crystal alignment film according to [8].

[10] A method for producing a liquid crystal alignment film, comprising the steps of applying the liquid crystal alignment agent according to any one of [1] to [7] to a substrate, baking the substrate, and irradiating the substrate with polarized ultraviolet light.

[0011] By using the liquid crystal aligning agent for alignment of the present invention, it is possible to obtain a liquid crystal alignment film that can form a liquid crystal display element having good image retention characteristics and excellent display quality. Furthermore, by using this liquid crystal alignment film, it is possible to efficiently realize the production of a liquid crystal display element having good image retention characteristics and excellent display quality. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below. The following description of the constituent elements may be based on representative embodiments or specific examples, but the present invention is not limited to such embodiments. The "liquid crystal alignment agent" of the present invention is a liquid crystal alignment agent that can impart anisotropy by forming a film thereof on a substrate and then performing an alignment treatment. Furthermore, the "tetracarboxylic acid derivative" of the present invention refers to a tetracarboxylic acid dianhydride, a tetracarboxylic acid diester, or a tetracarboxylic acid diester dihalide. Tetracarboxylic acid diesters and tetracarboxylic acid diester dihalides are sometimes collectively referred to as derivatives of tetracarboxylic acid dianhydrides. Furthermore, in the present invention, diamines and dihydrazides are sometimes referred to as "diamines." In the chemical formulae of this specification, * represents a bond.

[0013] <Liquid Crystal Alignment Agent of the Present Invention> The liquid crystal alignment agent for alignment of the present invention is a liquid crystal alignment agent containing polymer (K), which is at least one polymer selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, and is characterized in that the raw material composition of the polymer (K) contains at least one tetracarboxylic acid derivative represented by formula (I) and at least one diamine having a structure represented by formula (II).

[0014] In the present invention, the polyamic acid derivative refers to polyimide, partial polyimide, polyamic acid ester, polyamic acid-polyamide copolymer, and polyamideimide.

[0015] <Type of polymer> The polyamic acid and polyamic acid derivatives will be described in detail below.

[0016] Here, polyamic acid is a polymer synthesized by a polymerization reaction between a tetracarboxylic dianhydride represented by formula (AN) and a diamine represented by formula (DI), and has a constitutional unit represented by formula (PAA). When a liquid crystal alignment agent containing polyamic acid is heated and baked in the process of forming a liquid crystal alignment film, the polyamic acid is imidized, and a polyimide liquid crystal alignment film having a constitutional unit represented by formula (PI) can be formed. [ka]

[0017] In formula (AN), formula (PAA), and formula (PI), X 1 is a tetravalent organic group. In formula (DI), formula (PAA), and formula (PI), X 2 is a divalent organic group. 1 For preferred ranges and specific examples of the tetravalent organic group in X, reference can be made to the corresponding structures of the tetracarboxylic dianhydrides described in this specification. 2 For the preferred range and specific examples of the divalent organic group in the formula (I), reference can be made to the description of the corresponding structure of the diamine or dihydrazide described in the section on diamines in this specification.

[0018] Polyamic acid derivatives are compounds in which a portion of a polyamic acid is replaced with another atom or atomic group to modify its properties, and are particularly preferred for their increased solubility in solvents used in liquid crystal aligners. Examples of such polyamic acid derivatives include: 1) polyimides in which all amino and carboxyl groups in a polyamic acid undergo a dehydration ring-closure reaction; 2) partial polyimides in which a portion undergoes a dehydration ring-closure reaction; 3) polyamic acid esters in which the carboxyl groups in a polyamic acid are converted to esters; 4) polyamic acid-polyamide copolymers obtained by replacing some of the acid dianhydrides in a tetracarboxylic acid dianhydride compound with organic dicarboxylic acids; and 5) polyamideimides obtained by dehydration ring-closure of a portion or all of the polyamic acid-polyamide copolymer. Among these derivatives, polyimides include those having a structural unit represented by the above formula (PI), and polyamic acid esters include those having a structural unit represented by the following formula (PAE). [ka] In the formula (PAE), X 1 is a tetravalent organic group, and X 2 is a divalent organic group, and Y is independently an alkyl group. 1 , X 2 The preferred range and specific examples of X in formula (PAA) 1 , X 2 For Y, a linear or branched alkyl group having 1 to 6 carbon atoms is preferred, and a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, or a tertiary butyl group is more preferred.

[0019] The tetracarboxylic dianhydrides and diamines used in the synthesis of the polyamic acid may each be one type or two or more types.

[0020] When the polyamic acid of the present invention is converted into a polyamic acid derivative, a polyimide, the polyimide can be obtained by imidizing the resulting polyamic acid solution with a dehydrating agent such as an acid anhydride, such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride, and a dehydration ring-closing catalyst such as a tertiary amine, such as triethylamine, pyridine, or collidine, at a temperature of 20 to 150° C. Alternatively, the polyamic acid can be precipitated from the resulting polyamic acid solution using a large amount of a poor solvent (an alcoholic solvent such as methanol, ethanol, or isopropyl alcohol, or a glycol solvent), and the precipitated polyamic acid can be imidized in a solvent such as toluene or xylene with the dehydrating agent and dehydration ring-closing catalyst at a temperature of 20 to 150° C.

[0021] In the imidization reaction, the molar ratio of the dehydrating agent to the dehydration ring-closing catalyst is preferably 0.1 to 10. The combined amount of the dehydrating agent and the dehydration ring-closing catalyst is preferably 1.5 to 10 times the total molar amount of the tetracarboxylic dianhydride used in the synthesis of the polyamic acid. The degree of imidization can be controlled by adjusting the amounts of the dehydrating agent and catalyst used in the imidization reaction, the reaction temperature, and the reaction time, thereby obtaining a partial polyimide in which only a portion of the polyamic acid is imidized. The resulting polyimide can be separated from the solvent used in the reaction and redissolved in another solvent and used as a liquid crystal aligning agent, or it can be used as a liquid crystal aligning agent without separating it from the solvent.

[0022] Polyamic acid esters can be obtained by a synthesis method involving reacting a polyamic acid with a hydroxyl group-containing compound, a halide, an epoxy group-containing compound, or the like, or by a synthesis method involving reacting a tetracarboxylic acid diester or tetracarboxylic acid diester dichloride derived from a tetracarboxylic acid dianhydride with a diamine. Tetracarboxylic acid diesters derived from tetracarboxylic acid dianhydrides can be obtained, for example, by reacting the tetracarboxylic acid dianhydride with two equivalents of an alcohol to open the ring, and tetracarboxylic acid diester dichlorides can be obtained by reacting the tetracarboxylic acid diester with two equivalents of a chlorinating agent (e.g., thionyl chloride). The polyamic acid ester may have only an amic acid ester structure, or may be a partially esterified product in which both an amic acid structure and an amic acid ester structure coexist.

[0023] The polyamic acid or its derivative of the present invention can be produced in the same manner as known polyamic acids or their derivatives used in forming polyimide films. The total amount of the tetracarboxylic acid derivatives charged is preferably 0.9 to 1.1 moles per mole of the total amount of diamines.

[0024] The liquid crystal aligning agent of the present invention may contain only one kind of these polyamic acids, polyamic acid esters, and polyimides obtained by imidizing these, or may contain two or more kinds thereof.

[0025] The molecular weight of the polyamic acid or its derivative of the present invention, in terms of polystyrene equivalent weight average molecular weight (Mw), is preferably 5,000 to 500,000, more preferably 5,000 to 50,000. The molecular weight of the polyamic acid or its derivative can be determined by measurement using gel permeation chromatography (GPC).

[0026] The presence of the polyamic acid or its derivatives of the present invention can be confirmed by analyzing the solids obtained by precipitating the polyamic acid or its derivatives with a large amount of poor solvent using IR (infrared spectroscopy) or NMR (nuclear magnetic resonance analysis).Furthermore, the monomers used can be confirmed by analyzing an extract of an organic solvent obtained by decomposing the polyamic acid or its derivatives with an aqueous solution of a strong alkali such as KOH or NaOH using GC (gas chromatography), HPLC (high performance liquid chromatography), or GC-MS (gas chromatography mass spectrometry).

[0027] <Tetracarboxylic acid derivatives> The polymer (K) of the present invention contains the compound represented by formula (I) as a raw material, and may contain other tetracarboxylic acid derivatives. Specific examples of the compound represented by formula (I) and other tetracarboxylic acid derivatives are described below. <Compound represented by formula (I)> The compound represented by formula (I) used as the raw material for the polymer (K) of the present invention will be explained below. [ka] In formula (I), *1, *1', *2 and *2' are bonds, each independently bonded to a hydroxyl group, a chlorine atom or an alkoxy group having 1 to 6 carbon atoms, and at least one pair of *1 and *1' and at least one pair of *2 and *2' may be bonded to the same oxygen atom; R b1 , R b2 , R b3 , and R b4 are each independently a hydrogen atom or a methyl group, and at least one is a methyl group.

[0028] Specific examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, and a tertiary butoxy group. A methoxy group is preferred because of its ease of imidization.

[0029] Formula (I) includes forms in which all four bonds are bonded to a hydroxyl group, a chlorine atom, or an alkoxy group having 1 to 6 carbon atoms; forms in which one of the pair *1 and *1' and the pair *2 and *2' is bonded to the same oxygen atom, and the two bonds of the remaining pair are bonded to a hydroxyl group, a chlorine atom, or an alkoxy group having 1 to 6 carbon atoms; and forms in which both the pair *1 and *1' and the pair *2 and *2' are bonded to the same oxygen atom. Preferred are forms in which all four bonds are bonded to a hydroxyl group, a chlorine atom, or an alkoxy group having 1 to 6 carbon atoms, and forms in which both the pair *1 and *1' and the pair *2 and *2' are bonded to the same oxygen atom.

[0030] From the viewpoint of obtaining a liquid crystal alignment film with high liquid crystal alignment properties, R b1 and R b4 is a methyl group, and R b2 and R b3 is preferably hydrogen.

[0031] Preferred examples of the compound represented by formula (I) are listed below. [ka]

[0032] In the polymer (K) of the present invention, by using the compound represented by formula (I), a liquid crystal aligning agent capable of forming a liquid crystal alignment film having high liquid crystal alignment property can be obtained. Among the compounds represented by formula (I), it is preferable to use the compound represented by formula (I-1).

[0033] In the polymer (K) of the present invention, the compound represented by formula (I) is preferably used in an amount of 50 mol % or more, more preferably 80 mol % or more, and even more preferably 100 mol % of the total amount of the tetracarboxylic acid derivative used. A plurality of compounds represented by formula (I) may be used in combination.

[0034] <Tetracarboxylic acid derivatives other than those of formula (I)>

[0035] Below, we will explain tetracarboxylic acid derivatives other than those of formula (I), including tetracarboxylic acid dianhydrides represented by formulae (AN-1) to (AN-9), (AN-10-1), (AN-10-2), (AN-11), (AN-12), (AN-15), and (AN-16-1) to (AN-16-19). These tetracarboxylic acid dianhydrides may be converted into tetracarboxylic acid diesters or tetracarboxylic acid diester dichlorides, which may be used as raw materials for polymers.

[0036] [Tetracarboxylic acid dianhydride represented by formula (AN-1)] [ka] In formula (AN-1), G 10 R is a single bond, an alkylene group having 1 to 12 carbon atoms, a 1,4-phenylene group, a 1,4-cyclohexylene group, or formula (G10-1). 11 are independently a hydrogen atom or a methyl group. [ka] In formula (G10-1), X independently represents a single bond, —O—, —S—, or —NR 1 - and R 1 is a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, n is independently an integer of 1 to 5, and m is an integer of 1 to 3, and a group that is not fixedly bonded to any of the carbon atoms constituting the ring can be bonded to any available carbon atom in the ring.

[0037] Examples of the tetracarboxylic dianhydride represented by formula (AN-1) are listed below. [ka] [ka] In formulae (AN-1-2) and (AN-1-5), each m is independently an integer of 1 to 12.

[0038] [Tetracarboxylic acid dianhydride represented by formula (AN-2)] [ka] In formula (AN-2), G 11 X is a single bond, an alkylene group having 1 to 12 carbon atoms, a 1,4-phenylene group, or a 1,4-cyclohexylene group. 11 is a single bond or -CH2-. 12 are independently any of the following trivalent groups: [ka] G 12 When is >N-, G 11 is not a single bond or -CH2-, and X 11 is never a single bond.

[0039] Examples of the tetracarboxylic dianhydride represented by formula (AN-2) are listed below. [ka] In formula (AN-2-1), m is an integer of 1 to 12.

[0040] [Tetracarboxylic acid dianhydride represented by formula (AN-3)] [ka] In formula (AN-3), ring A 11 is a cyclohexane ring or a benzene ring.

[0041] Examples of the tetracarboxylic dianhydride represented by formula (AN-3) include compounds represented by the following formulae (AN-3-1) and (AN-3-2). [ka]

[0042] [Tetracarboxylic acid dianhydride represented by formula (AN-4)] [ka] In formula (AN-4), G 13 is a single bond, -(CH2) m -, -O-, -S-, -C(CH3)2-, -SO2-, -CO-, -C(CF3)2-, or a divalent group represented by the following formula (G13-1), where m is an integer of 1 to 12. 11 are each independently a cyclohexane ring or a benzene ring. 13 is ring A 11 It may be attached at any position of the [ka] In formula (G13-1), G 13a and G 13b are each independently a single bond or a divalent group represented by -O-, -CONH-, or -NHCO-. The phenylene group is preferably a 1,4-phenylene group or a 1,3-phenylene group.

[0043] Examples of the tetracarboxylic dianhydride represented by formula (AN-4) include compounds represented by the following formulae (AN-4-1) to (AN-4-31). [ka] [ka] In formula (AN-4-17), m is an integer of 1 to 12.

[0044] [ka] [ka]

[0045] [Tetracarboxylic acid dianhydride represented by formula (AN-5)] [ka] In formula (AN-5), R 11 are independently hydrogen atoms or methyl groups. 11 Among them, R in the benzene ring 11 is attached to any substitutable position on the benzene ring.

[0046] Examples of the tetracarboxylic dianhydride represented by formula (AN-5) include compounds represented by the following formulae (AN-5-1) to (AN-5-3). [ka]

[0047] [Tetracarboxylic acid dianhydride represented by formula (AN-6)] [ka] In formula (AN-6), X 11 are independently a single bond or -CH2-. 12 is -CH2-, -CH2CH2- or -CH=CH-. n is 1 or 2. When n is 2, two X 12 may be the same or different from each other.

[0048] Examples of the tetracarboxylic dianhydride represented by formula (AN-6) include compounds represented by the following formulae (AN-6-1) to (AN-6-12). [ka]

[0049] [Tetracarboxylic acid dianhydride represented by formula (AN-7)] [ka] In formula (AN-7), X 11 is a single bond or -CH2-.

[0050] Examples of the tetracarboxylic dianhydride represented by formula (AN-7) include compounds represented by the following formulae (AN-7-1) and (AN-7-2). [ka]

[0051] [Tetracarboxylic acid dianhydride represented by formula (AN-8)] [ka] In formula (AN-8), X 11 is a single bond or -CH2-. 12 is a hydrogen atom, a methyl group, an ethyl group, or a phenyl group. 12 is a cyclohexane ring or a cyclohexene ring.

[0052] Examples of the tetracarboxylic dianhydride represented by formula (AN-8) include compounds represented by the following formulae (AN-8-1) and (AN-8-2). [ka]

[0053] [Tetracarboxylic acid dianhydride represented by formula (AN-9)] [ka] In formula (AN-9), each r is independently 0 or 1.

[0054] Examples of the tetracarboxylic dianhydride represented by formula (AN-9) include compounds represented by the following formulae (AN-9-1) to (AN-9-3). [ka]

[0055] [Tetracarboxylic acid dianhydrides represented by formula (AN-10-1) and formula (AN-10-2)] [ka]

[0056] [Tetracarboxylic acid dianhydride represented by formula (AN-11)] [ka] In formula (AN-11), ring A 11 are independently a cyclohexane ring or a benzene ring.

[0057] Examples of the tetracarboxylic dianhydride represented by formula (AN-11) include compounds represented by the following formulae (AN-11-1) to (AN-11-3). [ka]

[0058] [Tetracarboxylic acid dianhydride represented by formula (AN-12)] [ka] In formula (AN-12), ring A 11 are each independently a cyclohexane ring or a benzene ring.

[0059] Examples of the tetracarboxylic dianhydride represented by formula (AN-12) include compounds represented by the following formulae (AN-12-1) to (AN-12-3). [ka]

[0060] [Tetracarboxylic acid dianhydride represented by formula (AN-15)] [ka] In formula (AN-15), w is an integer of 1 to 10.

[0061] Examples of the tetracarboxylic dianhydride represented by formula (AN-15) include compounds represented by the following formulae (AN-15-1) to (AN-15-3). [ka]

[0062] [Tetracarboxylic acid dianhydrides represented by formulas (AN-16-1) to (AN-16-19)] Other tetracarboxylic dianhydrides include compounds represented by the following formulae (AN-16-1) to (AN-16-19). [ka] [ka]

[0063] <Diamines> The polymer (K) of the present invention contains at least one diamine having a structure represented by formula (II) as a raw material, and may contain other diamines. Specific examples of the diamine having a structure represented by formula (II) and other diamines are described below.

[0064] <Diamines Having a Structure Represented by Formula (II)> The diamines having the structure represented by formula (II) used as the raw material for the polymer (K) of the present invention will be described below. [ka] In formula (II), *3 and *4 are bonds, each independently a bond bonded to a hydrogen atom or a carbon atom (provided that one or both of *3 and *4 are bonds bonded to a carbon atom); A 1is a monovalent hydrocarbon group having 5 or more carbon atoms, or a monovalent group having 5 or more carbon atoms and having -O- between the carbon-carbon bonds of the hydrocarbon group, and is preferably a monovalent hydrocarbon group having 5 to 10 carbon atoms, or a monovalent group having 5 to 10 carbon atoms and having -O- between the carbon-carbon bonds of the hydrocarbon group.

[0065] In order to obtain a liquid crystal alignment film having high liquid crystal alignment properties, the structure represented by formula (II) is preferably a structure represented by formula (III). [ka] In formula (III), *3 and *4 are bonds, each independently a bond bonded to a hydrogen atom or a carbon atom (provided that one or both of *3 and *4 are bonds bonded to a carbon atom); R a1 , R a2 and R a3 are each independently a monovalent chain hydrocarbon group having 1 to 7 carbon atoms, or a monovalent group having 1 to 7 carbon atoms and having -O- between the carbon-carbon bonds of the chain hydrocarbon group. a1 , R a2 and R a3 The total number of carbon atoms is 4 to 9.

[0066] Specific examples of diamines having the structure represented by formula (III) are given below. [ka] [ka]

[0067] In formulas (III-1) to (III-23), e each independently represents an integer of 2 to 10, and D is preferably a structure represented by formula (IV), more preferably a structure represented by formula (V), and even more preferably a structure represented by formulas (VI-1) to (VI-3). [ka] In formula (IV), A 1 is a monovalent hydrocarbon group having 5 or more carbon atoms, or a monovalent group having 5 or more carbon atoms and having -O- between the carbon-carbon bonds of the hydrocarbon group, and is preferably a monovalent hydrocarbon group having 5 to 10 carbon atoms, or a monovalent group having 5 to 10 carbon atoms and having -O- between the carbon-carbon bonds of the hydrocarbon group. [ka] R a1 , R a2 and R a3 are each independently a monovalent chain hydrocarbon group having 1 to 7 carbon atoms, or a monovalent group having 1 to 7 carbon atoms and having -O- between the carbon-carbon bonds of the chain hydrocarbon group. a1 , R a2 and R a3 The total number of carbon atoms is 4 to 9. [ka]

[0068] <Other diamines> Specific examples of diamines that can be used in combination with the diamines having the structure represented by formula (II) as raw materials for the polymer (K) of the present invention are described below.

[0069] [ka]

[0070] In formula (DI-1), G 20 is an alkylene having 1 to 12 carbon atoms or a group represented by formula (DI-1-a). 20 is alkylene having 1 to 12 carbon atoms, at least one of -CH2- may be replaced with -NH- or -O-, but these are not adjacent to each other, and at least one hydrogen atom of -CH2- may be replaced with a hydroxyl group or a methyl group. [ka] In formula (DI-1-a), each v is independently an integer of 1 to 6.

[0071] In formula (DI-3), formula (DI-6) and formula (DI-7), G 21 are independently a single bond, -NH-, -NCH3-, -O-, -S-, -SS-, -SO2-, -CO-, -COO-, -CONCH3-, -CONH-, -C(CH3)2-, -C(CF3)2-, -(CH2) m -, -O-(CH2) m -O-, -N(CH3)-(CH2) k -N(CH3)-, -(O-C2H4) m -O-, -O-CH2-C(CF3)2-CH2-O-, -O-CO-(CH2) m -CO-O-, -CO-O-(CH2) m -O-CO-, -(CH2) m -NH-(CH2) m -, -CO-(CH2) k -NH-(CH2) k -, -(NH-(CH2) m ) k -NH-, -CO-C3H6-(NH-C3H6) n -CO-, or -S-(CH2) m -S-, m is independently an integer of 1 to 12, k is an integer of 1 to 5, and n is 1 or 2.

[0072] In formula (DI-4), s is independently an integer of 0 to 2.

[0073] In formula (DI-5), G 33 is a single bond, -NH-, -NCH3-, -O-, -S-, -SS-, -SO2-, -CO-, -COO-, -CONCH3-, -CONH-, -C(CH3)2-, -C(CF3)2-, -(CH2) m -, -O-(CH2) m -O-, -(O-C2H4) m -O-, -O-CH2-C(CF3)2-CH2-O-, -O-CO-(CH2) m -CO-O-, -CO-O-(CH2) m-O-CO-, -(CH2) m -NH-(CH2) m -, -CO-(CH2) k -NH-(CH2) k -, -CO-C3H6-(NH-C3H6) n -CO-, or -S-(CH2) m -S-, -N(Boc)-(CH2) e -, -(CH2) m -N(Boc)-CONH-(CH2) m -, -(CH2) m -N(Boc)-(CH2) m -, or a group represented by the following formula (DI-5-a) or (DI-5-b), wherein m is independently an integer of 1 to 12, k is an integer of 1 to 5, e is an integer of 2 to 10, and n is 1 or 2. Boc is a tertiary-butoxycarbonyl group.

[0074] [ka] In formula (DI-5-a), each q is independently an integer of 0 to 6. 44 is a hydrogen atom, a hydroxyl group, an alkyl group having 1 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms.

[0075] In formula (DI-6) and formula (DI-7), G 22 are independently a single bond, -O-, -S-, -CO-, -C(CH3)2-, -C(CF3)2-, or an alkylene group having 1 to 10 carbon atoms.

[0076] At least one hydrogen atom of the cyclohexane ring and the benzene ring in Formulas (DI-2) to (DI-7) may be replaced with a fluorine atom, a chlorine atom, an alkyl group having 1 to 3 carbon atoms, a methoxy group, a hydroxyl group, a trifluoromethyl group, a carboxy group, a carbamoyl group, a phenylamino group, a phenyl group, or a benzyl group. In addition, in Formula (DI-4), at least one hydrogen atom of the cyclohexane ring and the benzene ring may be replaced with one selected from the group of groups represented by any of the following Formulas (DI-4-a) to (DI-4-i). In Formula (DI-5), G 33 When is a single bond, at least one hydrogen atom of the benzene ring may be replaced by NHBoc or N(Boc)2.

[0077] [ka] [ka] In formula (DI-4-a) and formula (DI-4-b), R 20 are independently a hydrogen atom or a methyl group. In formula (DI-4-f) and formula (DI-4-g), m is each independently an integer of 0 to 12, and Boc is a tertiary-butoxycarbonyl group.

[0078] In formulae (DI-2) to (DI-7), a group that is not fixed to a carbon atom constituting a ring indicates that the bonding position in the ring is arbitrary.

[0079] [ka] In formula (DI-11), r is 0 or 1. In formulas (DI-8) to (DI-11), the amino group bonded to the ring may be at any position.

[0080] [ka] In formula (DI-12), R 21and R 22 are each independently an alkyl group having 1 to 3 carbon atoms or a phenyl group, and G 23 are independently an alkylene group having 1 to 6 carbon atoms, a phenylene group, or a phenylene group substituted with an alkyl group; and w is an integer of 1 to 10.

[0081] In formula (DI-13), R 23 are independently an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a chlorine atom; p and q are each independently an integer of 0 to 4.

[0082] In formula (DI-14), ring B is a monocyclic heteroaromatic group, and R 24 is a hydrogen atom, a fluorine atom, a chlorine atom, an alkyl group, an alkoxy group, an alkenyl group, or an alkynyl group having 1 to 6 carbon atoms, and q is independently an integer of 0 to 4. When q is 2 or more, multiple R 24 may be the same or different. In formula (DI-15), ring C is a heterocyclic aromatic group or a heterocyclic aliphatic group. In formula (DI-16), G 24 represents a single bond, an alkylene group having 2 to 6 carbon atoms, or a 1,4-phenylene group; and r is 0 or 1.

[0083] In formula (DI-17), R 23 are independently an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or a chlorine atom, -NHBoc, or -N(Boc)2, p is independently an integer of 0 to 4, and R 25 are independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a tertiary butoxycarbonyl group, and Z is a divalent group containing an alkylene group having 1 to 10 carbon atoms. In the alkylene group having 1 to 10 carbon atoms, any number of -CH2- groups at any position may be replaced with -NH- or -CO-, but -NH- or -CO- groups cannot be adjacent to each other.

[0084] R 25Preferred examples of the divalent group containing alkylene having 1 to 10 carbon atoms in Z are -(CH2)m- and -CO-(CH2)4-CO-, where m is an integer of 1 to 10. Among these, -(CH2) m - is preferred, and -(CH2)2-, -(CH2)4- and -(CH2)6- are more preferred.

[0085] In formulas (DI-13) to (DI-17), a group that is not fixedly bonded to a carbon atom constituting a ring indicates that the bonding position in the ring is arbitrary. The bonding positions of the amino groups in the rings at both ends may be arbitrary, but the para and meta positions are preferred, and the para position is more preferred.

[0086] [ka] In formula (DIH-1), G 25 is a single bond, an alkylene group having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO2-, -C(CH3)2-, or -C(CF3)2-.

[0087] In formula (DIH-2), ring D is a cyclohexylene group, a phenylene group, or a naphthylene group, and at least one hydrogen atom of this group may be replaced with a methyl group, an ethyl group, or a phenyl group.

[0088] In formula (DIH-3), each ring E is independently a cyclohexylene group or a phenylene group, and at least one hydrogen atom of this group may be replaced with a methyl group, an ethyl group, or a phenyl group. The two rings E may be the same or different. Y is a single bond, an alkylene group having 1 to 20 carbon atoms, -CO-, -O-, -S-, -SO2-, -C(CH3)2-, or -C(CF3)2-. In formulas (DIH-2) and (DIH-3), the hydrazide group bonded to the ring may be bonded at any position.

[0089] Examples of diamines represented by formula (DI-1) are shown in the following formulas (DI-1-1) to (DI-1-9). [ka] In formula (DI-1-7) and formula (DI-1-8), each k is independently an integer of 1 to 3. In formula (DI-1-9), each v is independently an integer of 1 to 6.

[0090] Examples of diamines represented by formulas (DI-2) to (DI-3) are shown in the following formulas (DI-2-1), (DI-2-2), and (DI-3-1) to (DI-3-3). [ka]

[0091] Examples of diamines represented by formula (DI-4) are shown in the following formulas (DI-4-1) to (DI-4-27). [ka] [ka] [ka] [ka]

[0092] [ka] [ka] In formulae (DI-4-20) and (DI-4-21), each m is independently an integer of 1 to 12. Among these, it is preferable to use the formula (DI-4-1) as the raw material composition for the polymer (K).

[0093] [ka]

[0094] Examples of diamines represented by formula (DI-5) are shown below. [ka] In formula (DI-5-1), m is an integer of 1 to 12. Of these, it is preferable to use a compound of formula (DI-5-1) in which m is 2 or 4 as the raw material composition for the polymer (K).

[0095] [ka] In formula (DI-5-12) and formula (DI-5-13), each m is independently an integer of 1 to 12.

[0096] [ka] In formula (DI-5-16), v is an integer of 1 to 6.

[0097] [ka]

[0098] [ka] In formulas (DI-5-35) to (DI-5-37), m is independently an integer of 1 to 12; in formula (DI-5-38), k is independently an integer of 1 to 5; and in formula (DI-5-40), n is an integer of 1 or 2.

[0099] [ka] In formula (DI-5-44), each e is independently an integer of 2 to 10, and in formula (DI-5-45), R 43is a hydrogen atom, a (tert-butoxycarbonyl)amino group, or a bis(tert-butoxycarbonyl)amino group.

[0100] [ka] [ka] [ka]

[0101] Examples of diamines represented by formula (DI-6) are shown in the following formulas (DI-6-1) to (DI-6-7). [ka]

[0102] Examples of diamines represented by formula (DI-7) are shown in the following formulas (DI-7-1) to (DI-7-11). [ka] In formula (DI-7-3) and formula (DI-7-4), m is each independently an integer of 1 to 12, and n is independently 1 or 2.

[0103] [ka] [ka]

[0104] Examples of diamines represented by formula (DI-8) are shown in the following formulas (DI-8-1) to (DI-8-4). [ka]

[0105] Examples of diamines represented by formula (DI-9) are shown in the following formulas (DI-9-1) to (DI-9-3). [ka]

[0106] Examples of diamines represented by formula (DI-10) are shown in the following formulas (DI-10-1) and (DI-10-2). [ka]

[0107] Examples of diamines represented by formula (DI-11) are shown in the following formulas (DI-11-1) to (DI-11-3). [ka]

[0108] An example of the diamine represented by formula (DI-12) is shown in formula (DI-12-1) below. [ka]

[0109] Examples of diamines represented by formula (DI-13) are shown in the following formulas (DI-13-1) to (DI-13-13). [ka] [ka] [ka] Among these, it is preferable to use the formula (DI-13-1) as the raw material composition for the polymer (K).

[0110] Examples of diamines represented by formula (DI-14) are shown in the following formulas (DI-14-1) to (DI-14-9). [ka]

[0111] Examples of diamines represented by formula (DI-15) are shown in the following formulas (DI-15-1) to (DI-15-12). [ka] [ka]

[0112] An example of the diamine represented by formula (DI-16) is shown in formula (DI-16-1) below. [ka]

[0113] Examples of diamines represented by formula (DI-17) are shown below. [ka] In formula (DI-17-1) and formula (DI-17-5), k is independently an integer of 1 to 6. In formula (DI-17-2) to formula (DI-17-3), e is independently an integer of 1 to 10, and Boc is a tertiary-butoxycarbonyl group. In formula (DI-17-4), m is independently 1 or 2, and n is 1 or 2.

[0114] Examples of compounds represented by any of formulas (DIH-1) to (DIH-3) are shown below in formulas (DIH-1-1), (DIH-1-2), (DIH-2-1) to (DIH-2-3), and (DIH-3-1) to (DIH-3-6). [ka] In formula (DIH-1-2), m is an integer of 1 to 12.

[0115] [ka] [ka]

[0116] In the polymer (K) of the present invention, the use of diamines having a structure represented by formula (II) can improve image retention properties. In the polymer (K) of the present invention, the total amount of diamines having a structure represented by formula (II) is preferably 10 mol % or more of the total amount of diamines used. Multiple diamines having a structure represented by formula (II) may be used in combination.

[0117] In the polymer (L) of the present invention, the afterimage properties can be improved by not using a diamine having a structure represented by formula (II).

[0118] In the raw material composition used as a raw material for the polymer of the present invention, a portion of the diamines may be replaced with at least one selected from the group consisting of monoamines and monohydrazides. The ratio of the at least one selected from the group consisting of monoamines and monohydrazides to the diamines is preferably 40 mol% or less. Such a substitution can cause termination of the polymerization reaction during the production of polyamic acid and suppress further progress of the polymerization reaction. Therefore, such a substitution can easily control the molecular weight of the resulting polymer (polyamic acid or its derivative), thereby improving, for example, the coating properties of a liquid crystal aligning agent without impairing the effects of the present invention. The diamines that may be replaced with monoamines or monohydrazides may be one type or two or more types, as long as the effects of the present invention are not impaired. Examples of the monoamine include aniline, 4-hydroxyaniline, cyclohexylamine, n-butylamine, n-pentylamine, normal hexylamine, normal heptylamine, normal octylamine, normal nonylamine, normal decylamine, normal undecylamine, normal dodecylamine, normal tridecylamine, normal tetradecylamine, normal pentadecylamine, normal hexadecylamine, normal heptadecylamine, normal octadecylamine, normal eicosylamine, para-aminophenyltrimethoxysilane, and 3-aminopropyltriethoxysilane.

[0119] When the polymer of the present invention is a polyamic acid or a derivative thereof, the raw material composition thereof may further contain a monoisocyanate compound as a monomer. By including a monoisocyanate compound in the monomer, the terminals of the resulting polyamic acid or its derivative are modified, thereby adjusting the molecular weight. By using this terminal-modified polyamic acid or its derivative, for example, it is possible to improve the coating properties of a liquid crystal aligning agent without impairing the effects of the present invention. From the above-mentioned viewpoint, it is preferable that the content of the monoisocyanate compound in the monomer is 1 to 10 mol % relative to the total amount of the diamine and tetracarboxylic dianhydride in the monomer. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

[0120] The liquid crystal aligning agent of the present invention may be composed of two types of polymers, the polymer (K) and the polymer (L) of the present invention, or may be a mixture of the polymer of the present invention and a polymer other than the polymer of the present invention. In this specification, a liquid crystal aligning agent that is a mixture of two or more of the above-mentioned polymers may be referred to as a blend-type liquid crystal aligning agent.

[0121] The liquid crystal aligning agent of the present invention may further contain a solvent from the viewpoint of adjusting the coatability of the liquid crystal aligning agent and the concentration of the polyamic acid or its derivative. The solvent can be any solvent capable of dissolving polymer components without particular limitations. The solvent may be a wide range of solvents commonly used in the manufacturing process or application of polymer components such as polyamic acid and soluble polyimide, and may be appropriately selected depending on the intended use. The solvent may be a single solvent or a mixed solvent of two or more solvents.

[0122] Examples of the solvent include a solvent that is compatible with the polyamic acid or its derivatives, and other solvents intended to improve coating properties.

[0123] Examples of aprotic polar organic solvents that are compatible with polyamic acid or its derivatives include N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, dimethylimidazolidinone, N-methylcaprolactam, N-methylpropionamide, N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, diethylacetamide, N,N-dimethylisobutylamide, γ-butyrolactone, and γ-valerolactone. Among these, N-methyl-2-pyrrolidone, dimethylimidazolidinone, γ-butyrolactone, and γ-valerolactone are preferred.

[0124] Examples of other solvents intended to improve coating properties include ethylene glycol monoalkyl ethers such as ethylene glycol monobutyl ether and ethylene glycol monotertiary butyl ether, diethylene glycol monoalkyl ethers such as diethylene glycol monoethyl ether, and diethylene glycol dialkyl ethers such as diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, and diethylene glycol butyl methyl ether. Other examples include propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether and 1-butoxy-2-propanol, dipropylene glycol monoalkyl ethers such as dipropylene glycol monomethyl ether, triethylene glycol monoalkyl ethers, butyl cellosolve acetate, phenyl acetate, and ester compounds such as these acetates. Further examples include dialkyl malonates such as diethyl malonate, alkyl lactates, diisobutyl ketone, diacetone alcohol, 3-methyl-3-methoxybutanol, 4-methyl-2-pentanol, diisobutyl carbinol, tetralin, and isophorone.

[0125] Among these, diisobutyl ketone, 4-methyl-2-pentanol, diisobutyl carbinol, ethylene glycol monobutyl ether, ethylene glycol monotertiary butyl ether, diethylene glycol monoethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, diethylene glycol butyl methyl ether, 1-butoxy-2-propanol, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, or butyl cellosolve acetate is preferred.

[0126] The solid content concentration of the liquid crystal aligning agent of the present invention is not particularly limited, and an optimum value may be selected according to the various coating methods described below. Usually, in order to prevent unevenness and pinholes during coating, the solid content is preferably 0.1 to 30% by weight, more preferably 1 to 10% by weight, based on the weight of the varnish.

[0127] The preferred viscosity range of the liquid crystal aligning agent of the present invention varies depending on the application method, the concentration of the polyamic acid or its derivative, the type of polyamic acid or its derivative used, and the type and proportion of the solvent. For example, when applying using a printer, the viscosity is 5 to 100 mPa·s (more preferably 10 to 80 mPa·s). A thickness of 5 mPa·s or higher makes it easier to obtain a sufficient film thickness, while a thickness of 100 mPa·s or lower makes it easier to suppress printing unevenness. When applying using spin coating, a viscosity of 5 to 200 mPa·s (more preferably 10 to 100 mPa·s) is suitable. When applying using an inkjet coating device, a viscosity of 5 to 50 mPa·s (more preferably 5 to 20 mPa·s) is suitable. The viscosity of the liquid crystal aligning agent is measured by rotational viscosimetry, for example, using a rotational viscometer (TVE-20L type viscometer manufactured by Toki Sangyo Co., Ltd.) (measurement temperature: 25°C).

[0128] The liquid crystal aligning agent of the present invention may further contain various additives. Various additives can be selected and used according to the respective purposes in order to improve various properties of the liquid crystal alignment film. Examples are shown below.

[0129] <Alkenyl-substituted nadimide compounds> For example, the liquid crystal aligning agent of the present invention may further contain an alkenyl-substituted nadimide compound for the purpose of stabilizing the electrical properties of the liquid crystal display element over a long period of time. The alkenyl-substituted nadimide compound may be used alone or in combination of two or more. For the above-mentioned purpose, the content of the alkenyl-substituted nadimide compound is preferably 1 to 50 wt %, more preferably 1 to 30 wt %, and even more preferably 1 to 20 wt %, relative to the polyamic acid or its derivative. The alkenyl-substituted nadimide compound is preferably a compound that can be dissolved in a solvent that dissolves the polyamic acid or its derivative used in the present invention. Preferred alkenyl-substituted nadimide compounds include the alkenyl-substituted nadimide compounds disclosed in JP-A Nos. 2008-096979, 2009-109987, and 2013-242526. Particularly preferred alkenyl-substituted nadimide compounds include bis{4-(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide)phenyl}methane, N,N'-m-xylylene-bis(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide), or N,N'-hexamethylene-bis(allylbicyclo[2.2.1]hept-5-ene-2,3-dicarboximide).

[0130] <Compounds with radically polymerizable unsaturated double bonds> For example, the liquid crystal aligning agent of the present invention may further contain a compound having a radically polymerizable unsaturated double bond for the purpose of stabilizing the electrical characteristics of the liquid crystal display element over a long period of time. The compound having a radically polymerizable unsaturated double bond may be one type of compound or two or more types of compounds. Note that the compound having a radically polymerizable unsaturated double bond does not include alkenyl-substituted nadiimide compounds. Preferred examples of the compound having a radically polymerizable unsaturated double bond include N,N'-methylenebisacrylamide, N,N'-dihydroxyethylenebisacrylamide, ethylenebisacrylate, 4,4'-methylenebis(N,N-dihydroxyethyleneacrylateaniline), triallyl cyanurate, and other compounds having a radically polymerizable unsaturated double bond disclosed in JP 2009-109987 A, JP 2013-242526 A, WO 2014 / 119682 A, and WO 2015 / 152014 A. For the above purposes, the content of the compound having a radically polymerizable unsaturated double bond is preferably 1 to 50% by weight, more preferably 1 to 30% by weight, based on the polyamic acid or its derivative.

[0131] <Oxazine compounds> For example, the liquid crystal aligning agent of the present invention may further contain an oxazine compound for the purpose of stabilizing the electrical properties of a liquid crystal display element for a long period of time. The oxazine compound may be one type of compound or two or more types of compounds. For the above purpose, the content of the oxazine compound is preferably 0.1 to 50% by weight, more preferably 1 to 40% by weight, and even more preferably 1 to 20% by weight, based on the polyamic acid or its derivative.

[0132] The oxazine compound is preferably soluble in a solvent that dissolves polyamic acid or its derivatives and has ring-opening polymerizability. Preferred oxazine compounds include those represented by formula (OX-3-1), formula (OX-3-9), and formula (OX-3-10), as well as those disclosed in JP-A-2007-286597 and JP-A-2013-242526. [ka]

[0133] <Oxazoline compounds> For example, the liquid crystal aligning agent of the present invention may further contain an oxazoline compound for the purpose of stabilizing the electrical properties of a liquid crystal display element for a long period of time. The oxazoline compound is a compound having an oxazoline structure. The oxazoline compound may be one type of compound or two or more types of compounds. For the above purpose, the content of the oxazoline compound is preferably 0.1 to 50 wt % relative to the polyamic acid or its derivative, more preferably 1 to 40 wt %, and even more preferably 1 to 20 wt %. Preferred oxazoline compounds include the oxazoline compounds disclosed in JP-A Nos. 2010-054872 and 2013-242526. More preferably, 1,3-bis(4,5-dihydro-2-oxazolyl)benzene is used.

[0134] <Epoxy compounds> For example, the liquid crystal aligning agent of the present invention may further contain an epoxy compound for the purposes of stabilizing the electrical properties of a liquid crystal display element for a long period of time, improving the hardness of the film, or improving adhesion to a sealant. The epoxy compound may be one type of compound or two or more types of compounds. For the above purposes, the content of the epoxy compound is preferably 0.1 to 50% by weight, more preferably 1 to 20% by weight, and even more preferably 1 to 10% by weight, based on the polyamic acid or its derivative.

[0135] As the epoxy compound, various compounds having one or more epoxy rings in the molecule can be used. For the purpose of improving the hardness of the film or the adhesion to the sealant, a compound having two or more epoxy rings in the molecule is preferred, and a compound having three or four epoxy rings is more preferred.

[0136] Examples of the epoxy compound include the epoxy compounds disclosed in JP-A-2009-175715, JP-A-2013-242526, JP-A-2016-170409, and WO 2017 / 217413. Preferred epoxy compounds include N,N,N',N'-tetraglycidyl-4,4'-diaminodiphenylmethane, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, (3,3',4,4'-diepoxy)bicyclohexyl, 1,4-butanediol glycidyl ether, tris(2,3-epoxypropyl)isocyanurate, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, and N,N,N',N'-tetraglycidyl-m-xylenediamine. More preferred are 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane. In addition to the above, an oligomer or polymer having an epoxy ring can also be added. As the oligomer or polymer having an epoxy ring, the oligomer or polymer disclosed in JP-A-2013-242526 can be used.

[0137] <Silane compounds> For example, the liquid crystal aligning agent of the present invention may further contain a silane compound for the purpose of improving adhesion to a substrate and a sealant. For the above purpose, the content of the silane compound is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight, and even more preferably 0.5 to 10% by weight, based on the polyamic acid or its derivative.

[0138] Examples of silane compounds that can be used include silane coupling agents disclosed in Japanese Patent Application Laid-Open Nos. 2013-242526, 2015-212807, 2018-173545, and International Publication No. 2018 / 181566. Preferred silane coupling agents include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, para-aminophenyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-isocyanatepropyltriethoxysilane, and 3-ureidopropyltriethoxysilane.

[0139] In addition to the additives described above, compounds having a cyclocarbonate group, a hydroxyalkylamide moiety, or a hydroxyl group can also be added to increase the strength of the liquid crystal alignment film or stabilize the electrical properties of the liquid crystal display element over a long period of time. Specific examples of these compounds include those disclosed in JP 2016-118753 A and WO 2017 / 110976 A. Preferred examples of the compounds include those represented by the following formulae (HD-1) to (HD-4). These compounds are preferably used in an amount of 0.5 to 50% by weight, more preferably 1 to 30% by weight, and even more preferably 1 to 10% by weight, based on the polyamic acid or its derivative. [ka]

[0140] Furthermore, when improved antistatic properties are required, an antistatic agent can be used, and when imidization is to proceed at low temperatures, an imidization catalyst can be used, such as the imidization catalyst disclosed in JP-A-2013-242526.

[0141] <Liquid crystal alignment film>

[0142] The liquid crystal alignment film of the present invention is a film formed by heating a coating film of the liquid crystal aligning agent of the present invention described above. The liquid crystal alignment film of the present invention can be obtained by a conventional method for producing a liquid crystal alignment film from a liquid crystal aligning agent. For example, the liquid crystal alignment film of the present invention can be obtained through a step of forming a coating film of the liquid crystal aligning agent of the present invention, a step of heating and drying, and a step of heating and baking. The liquid crystal alignment film of the present invention is subjected to a treatment to impart anisotropy. Although anisotropy can be imparted by rubbing treatment, it is preferable to impart anisotropy by light irradiation.

[0143] A method for forming a liquid crystal alignment film using the liquid crystal aligning agent of the present invention will be described below.

[0144] The coating film can be formed by applying the liquid crystal aligning agent of the present invention to a substrate of a liquid crystal display element in the same manner as in the preparation of a normal liquid crystal alignment film. The substrate may be made of glass, silicon nitride, acrylic, polycarbonate, polyimide, or the like, which may be provided with an electrode such as ITO (Indium Tin Oxide), IZO (In2O3-ZnO), or IGZO (In-Ga-ZnO) electrode, or a color filter.

[0145] Generally known methods for applying a liquid crystal alignment agent to a substrate include a spinner method, a printing method, a dipping method, a dropping method, an ink jet method, etc. These methods can also be applied to the present invention.

[0146] Commonly known methods for the heat drying step include a method of heat treatment in an oven or infrared furnace, a method of heat treatment on a hot plate, etc. The heat drying step is preferably carried out at a temperature within a range in which the solvent can evaporate, and more preferably at a temperature relatively lower than the temperature in the heat baking step. Specifically, the heat drying temperature is preferably in the range of 30°C to 150°C, and more preferably in the range of 50°C to 120°C.

[0147] The heating and baking step can be carried out under conditions necessary for the polyamic acid or its derivative to undergo an imidization reaction. Baking of a coating film is generally carried out by heating in an oven or infrared furnace, or on a hot plate. These methods are also applicable to the present invention. Generally, the baking is preferably carried out at a temperature of about 90 to 300°C, more preferably 120 to 280°C, and even more preferably 150 to 250°C. The baking time is not particularly limited, but is usually 1 minute to 2 hours, and generally 10 to 40 minutes.

[0148] Heating may be carried out in several steps, and the temperature may be changed during the steps.

[0149] In order to align the liquid crystal in one direction relative to the horizontal and / or vertical direction, a known photo-alignment method can be suitably used as a means for imparting anisotropy to the liquid crystal alignment film.

[0150] The light used in the light irradiation step in the photo-alignment method can be, for example, ultraviolet light or visible light containing light with a wavelength of 150 to 800 nm. The light is not particularly limited as long as it can impart liquid crystal alignment ability to the thin film, but when it is desired to exert a strong alignment control force on the liquid crystal, polarized light is preferred, and linearly polarized light is more preferred.

[0151] The wavelength of the polarized light in the light irradiation step is preferably 150 to 400 nm, more preferably 200 to 400 nm, and even more preferably 200 to 300 nm. The irradiation dose of the polarized light is 0.001 to 10 J / cm 2is preferably 0.1 to 5 J / cm 2 The irradiation angle of the polarized light to the film surface is not particularly limited, but when it is desired to exert a strong alignment control force on the liquid crystal, it is preferable that the irradiation angle be as perpendicular as possible to the film surface from the viewpoint of shortening the alignment treatment time. Furthermore, the liquid crystal alignment film of the present invention can align the liquid crystal in a direction perpendicular to the polarization direction of the linearly polarized light by irradiating it with linearly polarized light.

[0152] The light source used in the light irradiation process can be an ultra-high pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a deep UV lamp, a halogen lamp, a metal halide lamp, a high power metal halide lamp, a xenon lamp, a mercury xenon lamp, an excimer lamp, a KrF excimer laser, a fluorescent lamp, an LED lamp, a sodium lamp, a microwave excited electrodeless lamp, or the like, without any restrictions.

[0153] In order to improve the liquid crystal alignment ability of the liquid crystal alignment film, the liquid crystal alignment film may be irradiated with light while being heated. In this case, the heating temperature is preferably in the range of 50°C to 250°C.

[0154] The light irradiation step can be carried out after the heat drying step or the heat baking step, and is preferably carried out after the heat baking step. Alternatively, the light irradiation step can be carried out simultaneously with the heat drying step.

[0155] The liquid crystal alignment film of the present invention is preferably subjected to additional heating after the light irradiation step. The heating temperature is the same as or higher than the temperature in the heating and baking step, and is preferably 150 to 300° C., more preferably 150 to 250° C., and even more preferably 200 to 250° C. The additional heating time is preferably 5 minutes to 2 hours, more preferably 5 to 60 minutes, and even more preferably 5 to 30 minutes.

[0156] A cleaning step can also be performed after the light irradiation step or the additional heating step. Specifically, the liquid crystal alignment film is immersed in a solvent. The immersion temperature is preferably 10 to 80°C, more preferably 20 to 50°C. Ultrasonic treatment is also preferred. The treatment time is preferably 1 minute to 1 hour, more preferably 1 minute to 30 minutes. The solvent used is not particularly limited as long as it dissolves decomposition products generated from the liquid crystal alignment film by ultraviolet irradiation. Examples of the solvent include water, methanol, ethanol, 2-propanol, acetone, methyl ethyl ketone, 1-methoxy-2-propanol, 1-methoxy-2-propanol acetate, butyl cellosolve, ethyl lactate, methyl lactate, diacetone alcohol, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, propyl acetate, butyl acetate, and cyclohexyl acetate. Among these, water, 2-propanol, 1-methoxy-2-propanol, and ethyl lactate are preferred from the viewpoints of versatility and safety. After immersion, it is preferable to heat or rinse the substrate, or both. The heating temperature is preferably 150 to 300°C, more preferably 200 to 230°C. The heating time is preferably 10 seconds to 30 minutes, more preferably 1 to 10 minutes. A low-boiling solvent such as water, methanol, ethanol, 2-propanol, acetone, or methyl ethyl ketone is preferably used for rinsing.

[0157] The thickness of the liquid crystal alignment film of the present invention is not particularly limited, but is preferably 10 to 300 nm, more preferably 30 to 150 nm. The thickness of the liquid crystal alignment film of the present invention can be measured by a known film thickness measuring device such as a step gauge or an ellipsometer.

[0158] The liquid crystal alignment film of the present invention can be suitably used for controlling the alignment of a liquid crystal composition in a liquid crystal display element. In addition to the use for aligning a liquid crystal composition in a liquid crystal display element, it can also be used for controlling the alignment of a liquid crystal material in all other liquid crystal elements such as a liquid crystal antenna, a light control window, an optical compensation material, a variable phase shifter, etc.

[0159] <Liquid crystal display element> The liquid crystal display element of the present invention is characterized by having the liquid crystal alignment film of the present invention, and can suppress bright spot defects caused by photodecomposition products, have good afterimage characteristics, and realize high display quality.

[0160] The liquid crystal display element of the present invention will be described in detail. The present invention is a liquid crystal display element having a pair of substrates arranged opposite to each other, electrodes formed on one or both of the opposing surfaces of the pair of substrates, liquid crystal alignment films formed on the opposing surfaces of the pair of substrates, a liquid crystal layer formed between the pair of substrates, a pair of polarizing films arranged to sandwich the opposing substrates, a backlight, and a driving device, wherein the liquid crystal alignment films are formed of the liquid crystal alignment film of the present invention.

[0161] The electrode is not particularly limited as long as it is formed on one surface of the substrate. Examples of such electrodes include vapor-deposited films of ITO or metal. The electrode may be formed over the entire surface of one surface of the substrate, or may be formed in a desired patterned shape. Examples of the desired electrode shape include a comb or zigzag structure. The electrode may be formed on one or both of the pair of substrates. The electrode formation pattern varies depending on the type of liquid crystal display element. For example, in the case of an IPS-type liquid crystal display element or an FFS-type liquid crystal display element (in-plane switching mode liquid crystal display element), the electrode is disposed on one of the pair of substrates, while in the case of other liquid crystal display elements, the electrode is disposed on both of the pair of substrates. The liquid crystal alignment film is formed on the substrate or the electrode.

[0162] The liquid crystal layer is formed by sandwiching a liquid crystal composition between the pair of substrates whose surfaces, on which the liquid crystal alignment film is formed, face each other. In forming the liquid crystal layer, spacers, such as fine particles or a resin sheet, which are interposed between the pair of substrates to form an appropriate gap, can be used as needed.

[0163] Known methods for forming a liquid crystal layer include a vacuum injection method and an ODF (One Drop Fill) method.

[0164] In the vacuum injection method, a gap (cell gap) is created so that the liquid crystal alignment film surfaces face each other, and a sealant is printed on the substrates, leaving an injection port for the liquid crystal. The substrates are then bonded together. After the cell gap defined by the substrate surfaces and the sealant is filled with liquid crystal using a vacuum pressure difference, the injection port is sealed to produce a liquid crystal display element.

[0165] In the ODF method, a sealant is printed on the outer periphery of the liquid crystal alignment film surface of one of a pair of substrates, liquid crystal is dropped into the area inside the sealant, and then the other substrate is attached so that the liquid crystal alignment film surface faces the other. The liquid crystal is then spread over the entire surface of the substrate, and then the entire surface of the substrate is irradiated with ultraviolet light to harden the sealant, thereby producing a liquid crystal display element.

[0166] In addition to UV curing sealants, thermosetting sealants are also known for use in bonding substrates. The sealant can be printed by screen printing, for example.

[0167] The liquid crystal composition is not particularly limited, and various liquid crystal compositions having positive or negative dielectric anisotropy can be used. Preferred liquid crystal compositions having positive dielectric anisotropy include those disclosed in Japanese Patent No. 3086228, Japanese Patent No. 2635435, JP-T-5-501735, JP-A-8-157826, JP-A-8-231960, JP-A-9-241644 (EP885272A1), JP-A-9-302346 (EP806466A2), JP-A-8-199168 (EP722998A), and the like. 1), JP-A-9-235552, JP-A-9-255956, JP-A-9-241643 (EP885271A1), JP-A-10-204016 (EP844229A1), JP-A-10-204436, JP-A-10-231482, JP-A-2000-087040, JP-A-2001-48822, and the like.

[0168] Preferable examples of the liquid crystal composition having negative dielectric anisotropy are disclosed in JP-A-57-114532, JP-A-2-4725, JP-A-4-224885, JP-A-8-40953, JP-A-8-104869, JP-A-10-168076, JP-A-10-168453, JP-A-10-236989, JP-A-10-2469 ... JP 10-236990, JP 10-236992, JP 10-236993, JP 10-236994, JP 10-237000 JP-A-10-237004, JP-A-10-237024, JP-A-10-237035, JP-A-10-237075, JP-A-10-23707 6, JP 10-237448 A (EP967261A1), JP 10-287874 A, JP 10-287875 A, JP 10-291945 A, JP 11-029581 A, JP 11-080049 A, JP 2000-256307 A, JP 2001-019965 A, JP 200 Examples of such liquid crystal compositions include those disclosed in JP-A-1-072626, JP-A-2001-192657, JP-A-2010-037428, WO 2011 / 024666, WO 2010 / 072370, JP-T-2010-537010, JP-A-2012-077201, and JP-A-2009-084362.

[0169] There is no problem in using a liquid crystal composition having a positive or negative dielectric anisotropy by adding one or more optically active compounds.

[0170] Furthermore, for example, the liquid crystal composition used in the liquid crystal display element of the present invention may further contain additives, for example, from the viewpoint of improving alignment. Such additives include photopolymerizable monomers, optically active compounds, antioxidants, UV absorbers, dyes, antifoaming agents, polymerization initiators, and polymerization inhibitors. Preferred photopolymerizable monomers, optically active compounds, antioxidants, UV absorbers, dyes, antifoaming agents, polymerization initiators, and polymerization inhibitors include compounds disclosed in International Publication No. WO 2015 / 146330 and the like.

[0171] A polymerizable compound can be mixed into the liquid crystal composition to adapt it to a PSA (polymer sustained alignment) mode liquid crystal display element. Preferred examples of the polymerizable compound include compounds having a polymerizable group, such as acrylate, methacrylate, vinyl compound, vinyloxy compound, propenyl ether, epoxy compound (oxirane, oxetane), and vinyl ketone. Preferred compounds include those disclosed in WO 2015 / 146330, etc. [Example]

[0172] The present invention will be described below with reference to examples, in which the evaluation methods and compounds used are as follows.

[0173] In the synthesis examples, the viscosity of the polymer solution was measured using a rotational viscometer (Model TVE-20L manufactured by Toki Sangyo Co., Ltd.) with a sample volume of 1.1 mL at a temperature of 25°C.

[0174] <Imidization rate of polyimide> The polyimide solution was poured into pure water, and the resulting precipitate was thoroughly dried under reduced pressure at room temperature. It was then dissolved in deuterated dimethyl sulfoxide and measured for 1H-NMR at room temperature using tetramethylsilane as a reference substance. The imidization rate [%] was calculated from the obtained 1H-NMR spectrum using the following formula (1). Imidization rate [%] = (1 - α × A1 / A2) × 100 ... (1) (In formula (1), A1 is the peak area derived from the proton of the NH group appearing at a chemical shift of around 10 ppm, A2 is the peak area derived from other protons, and α is the ratio of the number of other protons to one proton of the NH group in the polymer precursor (polyamic acid).)

[0175] <Tetracarboxylic acid derivatives> [ka]

[0176] <Diamine> [ka] [ka]

[0177] <Additives> [ka]

[0178] <Solvent> NMP: N-methyl-2-pyrrolidone GBL: gamma-butyrolactone BC: Butyl cellosolve (ethylene glycol monobutyl ether)

[0179] Varnish synthesis

[0180] [Synthesis Example 1] Synthesis of Varnish A1 A 100 mL three-neck flask equipped with a stirring blade and nitrogen inlet tube was charged with 1.49 g of the compound represented by formula (D-3) and 2.18 g of the compound represented by formula (D-8), and 54.0 g of NMP was added and stirred. Under a nitrogen atmosphere, 2.32 g of the compound represented by formula (T-1) was added to the solution and stirred at room temperature for 12 hours. 20.0 g of GBL and 20.0 g of BC were added, and the solution was heated and stirred at 60 °C until the viscosity of the solute polymer reached the desired value. Varnish A1, a polyamic acid solution with a solute viscosity of approximately 30 mPa·s and a resin concentration (solids concentration) of 6 wt%, was obtained.

[0181] [Synthesis Examples 2 to 6, 8 to 12] Synthesis of Varnishes A2 to 6, A8, and Varnishes B1 to 4 Varnishes A2 to A6, A8, and B1 to B4, which are polyamic acid solutions with a solids concentration of 6 wt% and a viscosity of approximately 30 mPa s, were synthesized in the same manner as in Synthesis Example 1, except that the compounds used as diamines and tetracarboxylic dianhydrides were changed as shown in Tables 1 and 2. The numbers in square brackets represent weights, and blank spaces indicate that the corresponding compound was not used.

[0182] [Synthesis Example 7] Synthesis of Varnish A7 A 100 mL three-neck flask equipped with a stirring blade and a nitrogen inlet tube was charged with 0.98 g of the compound represented by formula (D-1), 0.77 g of the compound represented by formula (D-2), 0.26 g of the compound represented by formula (D-4), and 1.28 g of the compound represented by formula (D-8), and 44.0 g of NMP was added and stirred. Under a nitrogen atmosphere, 2.72 g of the compound represented by formula (T-1) was added to this solution and stirred at room temperature for 12 hours. 0.96 g of pyridine and 3.73 g of acetic anhydride were added to this solution and heated at 60 °C for 4 hours to carry out a dehydration ring-closing reaction. After the dehydration ring-closure reaction, the solvent in the system was replaced with 44.0 g of fresh NMP, to which 50.0 g of GBL and 10.0 g of BC were added. The solution was heated and stirred at 60°C until the viscosity of the solute polymer reached the desired viscosity, yielding Varnish A7, a polyimide solution with a solute viscosity of approximately 30 mPa·s, a resin concentration (solid concentration) of 6 wt%, and an imidization rate of approximately 60%.

[0183] [Table 1]

[0184] [Table 2]

[0185] Varnish Preparation

[0186] [Example 1] Liquid crystal alignment agent 1 was prepared by blending varnish A1 and varnish B1 at a weight ratio of 3:7, diluting with an NMP / GBL / BC mixed solution (NMP / GBL / BC = 6 / 2 / 2 by weight) to a solids concentration of 4 wt%, stirring, and filtering through a 0.2 μm pore size filter. The liquid crystal alignment agent was then applied to glass substrates with FFS electrodes and column spacers using a spinner. After application, the substrates were heated at 60°C for 80 seconds to evaporate the solvent, and then baked at 230°C for 30 minutes to form a liquid crystal alignment film. Linearly polarized ultraviolet light with a wavelength range of 230 nm to 310 nm was irradiated perpendicularly to the substrates using a high-pressure mercury lamp (manufactured by Ushio Inc.) through a polarizer with a polarization wavelength range of 230 nm to 310 nm. The exposure energy was measured using a UV integrating light meter UIT-150 (photodetector: UVD-S254) manufactured by Ushio Inc., and was 0.4±0.05 J / cm at a wavelength of 254 nm. 2 The exposure time of the linearly polarized light was adjusted so that the film was heated at 230°C for 30 minutes. Next, the two substrates with the liquid crystal alignment films formed thereon were bonded together with the liquid crystal alignment film surfaces facing each other and a gap between the opposing liquid crystal alignment films for injecting a liquid crystal composition. At this time, the polarization directions of the linearly polarized light irradiated on each liquid crystal alignment film were parallel. Negative liquid crystal composition A was injected into this cell to prepare a liquid crystal cell (liquid crystal display element) with a cell thickness of 4 μm.

[0187] <Negative Liquid Crystal Composition A> [ka] (physical properties) Phase transition temperature NI: 75.7°C, dielectric anisotropy Δε: -4.1, refractive index anisotropy Δn: 0.101, viscosity η: 14.5 mPa·s.

[0188] <Evaluation of AC image lag using negative type liquid crystal composition A> AC image retention was measured according to the method described in International Publication WO 2000 / 43833. Specifically, the luminance-voltage characteristics (BV characteristics) of the fabricated liquid crystal cell were measured, and this was designated as the luminance-voltage characteristics before stress application: B (before). Next, a 4.5 V, 30 Hz AC current was applied to the liquid crystal cell for 20 minutes, and the luminance-voltage characteristics (BV characteristics) were measured again. This was designated as the luminance-voltage characteristics after stress application: B (after). Here, the luminance at a voltage of 1.3 V for each measured luminance-voltage characteristic was used as the characteristic value for B (before) and B (after), and the luminance change rate ΔB (%) was calculated using the following formula. The smaller the ΔB (%) value, the more effectively AC image retention was suppressed, i.e., the better the image retention characteristics. ΔB of less than 3% was rated as "good," and ΔB of 3% or more was rated as "poor." ΔB(%)={[B(after)-B(before)] / B(before)}×100

[0189] [Example 2, Comparative Example 1] Liquid crystal alignment agent 2 and comparative alignment agent 1 were prepared in the same manner as in Example 1, except that the varnishes shown in Table 3 were used instead of varnish A1 and varnish B1 and the blend ratios were changed to those shown in Table 3. Using the prepared liquid crystal alignment agents, AC image retention was evaluated in the same manner as in Example 1. The varnishes used, the blend ratios, and the results are shown in Table 3.

[0190] [Example 3] Varnish A3 and varnish B3 were blended at a weight ratio of 6:4 and further diluted with an NMP-GBL-BC mixed solution (NMP / GBL / BC = 4 / 5 / 1 weight ratio) to a solids concentration of 4 wt%. A compound represented by formula (Ad-1) was added to this solution in an amount equivalent to 5 wt% of the solids content in the solution, stirred at room temperature for 2 hours, and then filtered through a filter with a pore size of 0.2 μm to prepare liquid crystal alignment agent 5. AC image retention was evaluated in the same manner as in Example 1, except for the method of preparing the liquid crystal alignment agent. The evaluation results are shown in Table 3.

[0191] [Examples 4 to 6] Liquid crystal alignment agents 4 to 6 were prepared in the same manner as in Example 3, except that the varnishes and additives shown in Table 3 were used instead of varnish A3 and varnish B3, and the blend ratios were changed to those shown in Table 3. Using the prepared liquid crystal alignment agents, AC image retention was evaluated in the same manner as in Example 1. The varnishes used, the blend ratios, and the results are shown in Table 3.

[0192] [Table 3]

[0193] In Examples 1 to 7, the AC afterimage had good results, whereas in Comparative Example 1, the AC afterimage had poor results.

[0194] [Example 8] A liquid crystal cell (liquid crystal display element) having a cell thickness of 4 μm was prepared in the same manner as in Example 1, except that the negative liquid crystal composition A was changed to the positive liquid crystal composition B.

[0195] <Positive Liquid Crystal Composition B> [ka] (physical properties) Phase transition temperature NI: 100.1°C, dielectric anisotropy Δε: 5.1, refractive index anisotropy Δn: 0.093, viscosity η: 25.6 mPa·s.

[0196] Comparative Example 2 A liquid crystal cell (liquid crystal display element) having a cell thickness of 4 μm was produced in the same manner as in Example 8, except that the liquid crystal alignment agent 1 was changed to the comparative alignment agent 1.

[0197] <Evaluation of AC image lag using positive liquid crystal composition B> AC image retention was measured according to the method described in International Publication WO 2000 / 43833. Specifically, the luminance-voltage characteristics (BV characteristics) of the fabricated liquid crystal cell were measured, and this was designated as the luminance-voltage characteristics before stress application: B (before). Next, a 4.5 V, 30 Hz AC current was applied to the liquid crystal cell for 20 minutes, and the luminance-voltage characteristics (BV characteristics) were measured again. This was designated as the luminance-voltage characteristics after stress application: B (after). Here, the luminance at a voltage of 1.3 V for each measured luminance-voltage characteristic was used as the characteristic value for B (before) and B (after), and the luminance change rate ΔB (%) was calculated using the following formula. A smaller ΔB (%) value indicates better suppression of AC image retention, i.e., better image retention characteristics. ΔB less than 5% was rated as "good," and ΔB greater than 5% was rated as "poor." The evaluation results are shown in Table 4. ΔB(%)={[B(after)-B(before)] / B(before)}×100

[0198] [Table 4]

[0199] In Example 8, the AC afterimage was good, whereas in Comparative Example 2, the AC afterimage was poor. [Industrial Applicability]

[0200] By using the liquid crystal aligning agent of the present invention, it is possible to produce a liquid crystal alignment film that can form a liquid crystal display element having good afterimage characteristics and excellent display quality.

Claims

1. At least one selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide A liquid crystal aligning agent containing a polymer (K) which is at least one kind of polymer, The raw material composition of the polymer (K) is a liquid crystal aligning agent containing at least one tetracarboxylic acid derivative represented by formula (I) and at least one diamine having a structure represented by formula (II). 【Chemistry 1】 In formula (I), *1, *1', *2 and *2' are bonds, each independently bonding to a hydroxyl group, a chlorine atom or an alkoxy group having 1 to 6 carbon atoms, and at least one pair of *1 and *1' and at least one pair of *2 and *2' may bond to the same oxygen atom; R ｂ１ , R ｂ２ , R ｂ３ , and R ｂ４ are each independently a hydrogen atom or a methyl group, and at least one is a methyl group. 【Chemistry 2】 In formula (II), *3 and *4 are bonds, each independently a bond bonded to a hydrogen atom or a carbon atom (provided that one or both of *3 and *4 are bonds bonded to a carbon atom); A １ is a monovalent hydrocarbon group having 5 or more carbon atoms, or a monovalent group having 5 or more carbon atoms and having —O— between the carbon-carbon bonds of the hydrocarbon group.

2. In the formula (II), A １ is a monovalent hydrocarbon group having 5 to 10 carbon atoms, or a monovalent group having 5 to 10 carbon atoms and having -O- between the carbon-carbon bonds of the hydrocarbon group, the liquid crystal aligning agent according to claim 1.

3. A liquid crystal aligning agent further comprising a polymer (L) which is at least one polymer selected from the group consisting of polyamic acid, polyamic acid ester, and polyimide, The liquid crystal aligning agent according to claim 2, wherein the raw material composition of the polymer (L) does not contain a diamine having a structure represented by formula (II).

4. The liquid crystal aligning agent according to claim 3 , wherein the structure represented by formula (II) is a structure represented by formula (III): 【Transformation 3】 In formula (III), *3 and *4 are bonds, each independently a bond bonded to a hydrogen atom or a carbon atom (provided that one or both of *3 and *4 are bonds bonded to a carbon atom); R ａ１ , R ａ２ and R ａ３ are each independently a monovalent chain hydrocarbon group having 1 to 7 carbon atoms, or a monovalent group having 1 to 7 carbon atoms and having —O— between the carbon-carbon bonds of the chain hydrocarbon group. ａ１ , R ａ２ and R ａ３ The total number of carbon atoms is 4 to 9.

5. The liquid crystal aligning agent according to claim 4, wherein the compound represented by formula (I) is a compound represented by formula (I-1): 【Chemistry 4】

6. The raw material composition of the polymer (K) contains at least one compound represented by formula (DI-4-1), (DI-5-1) or formula (DI-13-1): A liquid crystal aligning agent according to claim 5. 【Transformation 5】 In formula (DI-5-1), m is 2 or 4.

7. The liquid crystal aligning agent according to claim 1 , which is used in a photo-alignment type in-plane switching liquid crystal display element.

8. A liquid crystal alignment film formed from the liquid crystal aligning agent according to claim 1 .

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

10. A method for producing a liquid crystal alignment film, comprising the steps of: applying the liquid crystal aligning agent according to claim 1 to a substrate; baking the substrate; and irradiating the substrate with polarized ultraviolet light.

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