JP2009265486A - Liquid crystal-aligning agent, liquid crystal alignment layer, and liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal-aligning agent which gives a liquid crystal alignment layer that shows excellent liquid crystal alignment regulating power (pretilt angle developing property of liquid crystal) and prevents residual DC from accumulating when heat stress is applied, the accumulation of the residual DC being considered to be one of the causes of the burn-in of a liquid crystal panel. <P>SOLUTION: The liquid crystal-aligning agent contains: a polymer having specific repetition units; and at least one polymer selected from the group consisting of polyamic acid, which is obtained by reacting tetracarboxylic acid 2-anhydride with diamine, and an imidized polymer thereof. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal aligning agent, a liquid crystal alignment film, and a liquid crystal display element. More specifically, a liquid crystal aligning agent that provides a liquid crystal aligning film that exhibits excellent liquid crystal alignment regulating power (pretilt angle developability) and that can suppress the accumulation of residual DC when a thermal stress is applied, and a liquid crystal formed from the liquid crystal aligning agent The present invention relates to an alignment film and a liquid crystal display element containing the liquid crystal alignment film.

Since LCD calculators were mass-produced for the first time, liquid crystal display devices have been developed from the viewpoint of space saving and low power consumption, such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, personal digital assistants, digital cameras, Applications in various fields such as mobile phones, various monitors, and LCD TVs are advancing, and active development is continuing.
As the liquid crystal display element, a nematic liquid crystal is used, and a TN (twisted nematic) type liquid crystal display element or TN type in which the major axis of liquid crystal molecules is continuously twisted by 90 ° from one substrate to the other substrate. STN (Super Twisted Nematic) type liquid crystal display elements that have a higher contrast than liquid crystal display elements have been widely used. In order to further improve the display quality of the liquid crystal display, a VA (Vertical Alignment) type liquid crystal display element having a small viewing angle dependency, an IPS (In Plane Switching) type liquid crystal display element, a small viewing angle dependency and a high-speed video screen. Optically compensated bend (Optical Compensated Birefringence = OCB) type liquid crystal display elements having excellent responsiveness have been developed.

In the liquid crystal display element, a member that controls liquid crystal alignment is a liquid crystal alignment film. A liquid crystal alignment film is generally formed by applying a so-called “rubbing process” in which a liquid crystal aligning agent containing an organic resin is applied to a substrate, then the solvent is removed to form a coating film, and the coating film is rubbed in a certain direction. Has been. Here, as the organic resin, polyamic acid or imidized polymer obtained by imidizing polyamic acid is widely used, but conventionally known polyamic acid or liquid crystal aligning agent containing the imidized polymer thereof is used. In order to impart a liquid crystal alignment regulating force (pretilt angle developability of liquid crystal) to the liquid crystal alignment film to be formed, a method of introducing a large hydrophobic substituent into the side chain of the polymer has been proposed (Patent Documents 1 to 3). 3). According to this technique, with the introduction of a large hydrophobic substituent, the solubility of the polyamic acid or its imidized polymer in the solvent decreases, and problems such as deterioration in the coating property of the liquid crystal aligning agent occur. There is a demand for a new liquid crystal aligning agent that can impart a liquid crystal alignment regulating force without causing a problem.
In addition, since the liquid crystal alignment film is a member that is in direct contact with liquid crystal molecules, it is known that the electrical characteristics of the liquid crystal alignment film have a very large effect on the image sticking (charge accumulation) and voltage holding ratio of the liquid crystal panel. Yes. Therefore, it is expected to improve the seizure resistance of the liquid crystal panel by improving the liquid crystal alignment film. For example, Patent Document 4 and Patent Document 5 propose a technique for optimizing the composition of the liquid crystal alignment film to facilitate the diffusion of accumulated charges (reducing the afterimage erasing time). However, even with this technique, the improvement of the seizure property upon application of heat stress is insufficient.
In recent years, as liquid crystal panels are applied to liquid crystal televisions and high-quality monitors, the liquid crystal alignment film has a characteristic that panel burn-in does not occur even if the liquid crystal panel is driven for a long time in order to achieve high-quality display performance. There is an urgent need for further improvement.
JP-A-6-136122 Japanese Patent No. 2893671 JP-A-9-241646 JP 2003-295194 A JP 2004-94179 A JP 2002-327058 A JP-A-6-222366 JP-A-6-281937 JP-A-5-107544

The present invention has been made based on the circumstances as described above, and its purpose is to exhibit excellent liquid crystal alignment regulating power (liquid crystal pre-tilt angle expression) and is considered to be one of the factors that cause liquid crystal panel image sticking. To provide a liquid crystal aligning agent capable of providing a liquid crystal aligning film capable of suppressing the accumulation of residual DC upon application of thermal stress, a liquid crystal aligning film having the above characteristics, and a liquid crystal display element excellent in seizure resistance after heat stress. It is in.
Other objects and advantages of the present invention will become apparent from the following description.

In accordance with the present invention, the above objects and advantages of the present invention are primarily as follows:
Following formula (1)

(In the formula (1), R ^I is a hydrogen atom or a methyl group, A ¹ is a single bond, a phenylene group, or the following formulas (A ¹ -1) to (A ¹ -5)

_{^{- (CH 2) k -O- *}} (A 1 -5)
(In the above formula, i is 0 or 2, respectively, j is 0 or 1, k is an integer of 1 to 6, and “*” is a bond attached thereto, respectively. Is bound to B ^1. )
B ¹ is an alkylphenyl group or an alkylcyclohexyl group having an alkyl group having 4 to 10 carbon atoms. )
A polymer having a repeating unit represented by:
This is achieved by a liquid crystal aligning agent containing a polyamic acid obtained by reacting tetracarboxylic dianhydride and diamine and at least one polymer selected from the group consisting of imidized polymers thereof.
The above objects and advantages of the present invention are secondly achieved by a liquid crystal alignment film formed from the above liquid crystal aligning agent, and thirdly by a liquid crystal display device comprising the above liquid crystal alignment film.

  According to the present invention, a liquid crystal aligning agent that provides a liquid crystal alignment film that exhibits excellent liquid crystal alignment regulating power (liquid crystal pretilt angle expression) while suppressing the accumulation of residual DC upon application of thermal stress. A liquid crystal alignment film having the above characteristics and a liquid crystal display element excellent in seizure resistance are provided.

Hereinafter, the present invention will be described in detail.
The liquid crystal aligning agent of this invention reacts the polymer (henceforth "polymer (1)") which has a repeating unit represented by the said Formula (1), tetracarboxylic dianhydride, and diamine. It contains at least one polymer selected from the group consisting of the resulting polyamic acid and its imidized polymer.
<Polymer (1)>
The polymer (1) contained in the liquid crystal aligning agent of this invention is a polymer which has a repeating unit represented by the said Formula (1).
In the phenylene group of A ¹ in the above formula (1) or the divalent group represented by the above formulas (A ¹ -1) to (A ¹ -4), the bond position of the bond is 4-position in any case. Preferably there is. K in (A ¹ -5) is preferably an integer of 2 to 4, and particularly preferably 2.
As the alkyl group having 4 to 10 carbon atoms of the alkylphenyl group or alkylcyclohexyl group represented by B ¹ in the above formula (1), a linear alkyl group is preferable, and the substitution position of the alkyl group is a phenyl group or cyclohexyl. The 4-position of the group is preferred. Examples of the alkylcyclohexyl group having an alkyl group having 4 to 8 carbon atoms of B ¹ in the above formula (1) include 4-n-pentylcyclohexyl group, 4-n-hexylcyclohexyl group, 4-n-heptylcyclohexyl group, A 4-n-octylcyclohexyl group, a 4-n-nonylcyclohexyl group, a 4-n-decylcyclohexyl group, and the like can be given.
Specific examples of the repeating unit represented by the above formula (1) include, for example, the following formulas (1-1) to (1-8):

The repeating unit represented by each of these can be mentioned. Among these, the repeating unit represented by the above formula (1-1) is preferable because it is particularly excellent in the balance between the pretilt angle expression and the electrical characteristics.
In addition to the repeating unit represented by the above formula (1), the polymer (1) has the following formula (2)

(In Formula (2), R ^II is a hydrogen atom or a methyl group, A ² is a single bond, a methylene group or an alkylene group having 2 to 10 carbon atoms, and B ² is a cyclic ether structure having 2 to 10 carbon atoms. A group having
A repeating unit represented by the following formula (3):

(In Formula (3), R ^III is a hydrogen atom, a methyl group or a carboxymethyl group; B ³ is a hydrogen atom, a methyl group or a carboxyl group; provided that when R ^III is a carboxymethyl group, B ³ is It is not a carboxyl group.)
A repeating unit represented by the following formula (4):

(In Formula (4), A ⁴ is a divalent group containing a single bond, oxygen atom, sulfur atom, nitrogen atom or silicon atom, and B ⁴ is an aryl group having 6 to 30 carbon atoms or 4 to 10 carbon atoms. Of the alicyclic group.)
A repeating unit represented by the following formula (5):

(In Formula (5), R ^IV is a hydrogen atom or a methyl group, A ⁵ is a divalent group containing a single bond, an oxygen atom, a sulfur atom, a nitrogen atom or a silicon atom, and B ⁵ is a hydrogen atom, It is an alkyl group having 1 to 20 carbon atoms or an aryl group having 6 to 30 carbon atoms.)
And a repeating unit represented by the following formula (6)

(In the formula (6), R ^V is a hydrogen atom or a methyl group, A ⁶ is a single bond or —C (═O) —O— * (where “*” is a bond attached thereto) denotes a bond with B ^{6.), B 6} is an alkylene group, a divalent alicyclic group an arylene group or a 4 to 10 carbon atoms having from 6 to 30 carbon atoms of 2 to 10 carbon atoms.)
It may have at least one repeating unit selected from the group consisting of repeating units represented by:
The cyclic ether structure contained in the repeating unit represented by the above formula (2) is subjected to a thermal crosslinking reaction by applying a liquid crystal aligning agent of the present invention to form a coating film, followed by heat treatment (post-baking), Thereby, the heat resistance, liquid crystal resistance (solvent resistance) and film density of the liquid crystal alignment film obtained can be further improved, and the diffusion of impurity ions contained in the liquid crystal into the liquid crystal alignment film can be further reduced. Liquid crystal alignment in which the decrease in voltage holding ratio and burn-in problem can be solved more reliably even when thermal stress is applied to the liquid crystal display element obtained by these effects or the liquid crystal panel is driven for a long time. Since the liquid crystal aligning agent which gives a film | membrane can be obtained, it is preferable that a polymer (1) has a repeating unit represented by the said Formula (2) with the repeating unit represented by the said Formula (1).
Therefore, as the cyclic ether structure having 2 to 10 carbon atoms of B ² in the above formula (2), a 1,2-epoxy structure or a 1,3-epoxy structure having thermal crosslinking reactivity is preferable, and the reactivity is excellent. And a 1,2-epoxy structure is more preferable. As the repeating unit represented by the above formula (2), in the above formula (2), A ² is a methylene group or an alkylene group having 2 to 10 carbon atoms, and B ² is a group having a 1,2-epoxy structure. A certain repeating unit is preferable, and a repeating unit in which A ² is a methylene group or an alkylene group having 2 or 5 carbon atoms and B ² is a group having a 1,2-epoxy structure is more preferable.
The repeating unit represented by the above formula (3) improves the compatibility between the polymer (1) and at least one polymer selected from the group consisting of polyamic acid and its imidized polymer. When the polymer (1) has a repeating unit represented by the above formula (2), it can be contained in the polymer (1) for the purpose of promoting the crosslinking reaction of the cyclic ether structure.

The repeating unit represented by the above formula (4) or the repeating unit represented by the above formula (5) can be included in the polymer (1) in order to further improve the heat resistance of the obtained liquid crystal alignment film. .
A ⁴ in the above formula (4) is preferably a single bond. Examples of the aryl group having 6 to 30 carbon atoms of B ⁴ in the formula (4) include, for example, a phenyl group, a naphthyl group, an anthracenyl group, a fluorenyl group, etc .; For example, a cyclopentyl group, a cyclohexyl group, etc. can be mentioned, respectively, and especially a phenyl group or a cyclohexyl group is preferable.
A ⁵ in the above formula (5) is preferably a single bond. Examples of the alkyl group having 1 to 20 carbon atoms of B ⁵ in the above formula (5) include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, and n-to. Examples of the aryl group having 6 to 30 carbon atoms include a phenyl group, a 4-biphenyl group, a 2-biphenyl group, a 1-naphthalenyl group, and a 2-naphthalenyl group. Of these, a phenyl group is preferred.
The repeating unit represented by the above formula (6) is for the purpose of improving the compatibility between the polymer (1) and at least one polymer selected from the group consisting of a polyamic acid and an imidized polymer thereof. It can be included in the polymer (1).
Examples of the alkylene group having 2 to 10 carbon atoms of B ⁶ in the above formula (6) include an ethylene group and a 1,4-butylene group; and examples of the arylene group having 6 to 30 carbon atoms include a phenylene group; Examples of the divalent alicyclic group having 4 to 10 carbon atoms include a cyclohexane-1,4-diyl group.

The polystyrene-converted weight average molecular weight (hereinafter referred to as “Mw”) measured using gel permeation chromatography (GPC) for the polymer (1) is preferably 2 × 10 ³ to 1 × 10 ⁶ , more preferably. Is 5 × 10 ^{3 to} 5 × 10 ⁵ , particularly preferably 1 × 10 ⁴ to 4 × 10 ⁵ . If Mw is less than 2 × 10 ³ , panel characteristics may be deteriorated due to elution of low molecular components (causing a decrease in voltage holding ratio or panel seizure). On the other hand, when it exceeds 1 × 10 ⁶ , the solution viscosity of the obtained liquid crystal aligning agent becomes too high, which may cause a problem in applicability. The molecular weight distribution (hereinafter referred to as “Mw / Mn”. Mn represents the number average molecular weight in terms of polystyrene) is preferably 20.0 or less, more preferably 15.0 or less, and particularly preferably 10.0 or less. is there. By reducing Mw / Mn, it becomes easy to obtain a liquid crystal aligning agent that has excellent coating properties and does not cause the problem of deterioration of panel characteristics due to elution of the low molecular components described above.
The polymer (1) as described above is, for example, the following formula (1 ′)

(In formula (1 ′), R ^I , A ¹ and B ¹ have the same meanings as in formula (1)).
(Hereinafter referred to as “monomer (1 ′)”) or compound (1 ′) and the following formula (2 ′)

(In the formula (2 ′), R ^II , A ² and B ² have the same meaning as in the above formula (2).)
(Hereinafter referred to as “monomer (2 ′)”), the following formula (3 ′)

(In formula (3 ′), R ^III and B ³ each have the same meaning as in formula (3) above.)
(Hereinafter referred to as “monomer (3 ′)”), the following formula (4 ′)

(In the formula (4 ′), A ⁴ and B ⁴ have the same meaning as in the above formula (4).)
(Hereinafter referred to as “monomer (4 ′)”), the following formula (5 ′)

(In formula (5 ′), R ^IV , A ⁵ and B ⁵ have the same meanings as in formula (5) above.)
(Hereinafter referred to as “monomer (5 ′)”) and the following formula (6 ′)

(In the formula (6 ′), R ^V , A ⁶ and B ⁶ have the same meaning as in the above formula (6).)
And at least one selected from the group consisting of compounds represented by the formula (hereinafter referred to as “monomer (6 ′)”), preferably in a suitable solvent in the presence of a suitable polymerization initiator. Can be synthesized.
The monomer (1 ′) is a monomer that leads to the repeating unit represented by the above formula (1). The monomer (1 ′) can be obtained, for example, by reacting a halogenated (meth) acryloyl and the compound B ¹ -A ¹ -OH according to a known esterification reaction.
The monomer (2 ′) is a monomer that leads to the repeating unit represented by the above formula (2), and specific examples thereof include, for example, glycidyl acrylate, glycidyl methacrylate, and 3,4-epoxy acrylate. Examples include butyl, methacrylic acid-3,4-epoxybutyl, acrylic acid-6,7-epoxyheptyl, methacrylic acid-6,7-epoxyheptyl, α-ethylacrylic acid-6,7-epoxyheptyl, and the like. . Among these, glycidyl acrylate or glycidyl methacrylate is preferable in that the obtained liquid crystal alignment film has a high film density and can exhibit excellent electrical characteristics and reliability of electrical characteristics.
The monomer (3 ′) is a monomer that leads to the repeating unit represented by the above formula (3). Specific examples thereof include maleic acid, fumaric acid, citraconic acid, mesaconic acid, itaconic acid, acrylic Examples include acid, methacrylic acid, and crotonic acid. Among these, the compatibility between the polymer (1) and the polyamic acid and its imidized polymer is good, and the obtained liquid crystal alignment film has a high film density and exhibits high reliability in electrical characteristics and electrical characteristics. Acrylic acid or methacrylic acid is preferred.

The monomer (4 ′) is a monomer that leads to the repeating unit represented by the above formula (4). Specific examples thereof include N-phenylmaleimide, N-naphthylmaleimide, and N-anthracenylmaleimide. , N-fluorenylmaleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide, and the like. Among these, N-phenylmaleimide or N-cyclohexylmaleimide is preferable.
The monomer (5 ′) is a monomer that leads to the repeating unit represented by the above formula (5). Specific examples thereof include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, Mention of α-olefins such as 1-heptene, 1-octene, 1-nonene, 1-decene and styrene, 4-vinylbiphenyl, 2-vinylbiphenyl, 1-vinylnaphthalene, 2-vinylnaphthalene, α-methylstyrene Of these, styrene is preferred.
The monomer (6 ′) is a monomer that leads to the repeating unit represented by the above formula (6), and specific examples thereof include, for example, isopropenylphenol, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, Examples thereof include 4-hydroxybutyl acrylate and 1,4-cyclohexanedimethanol monoacrylate.

The use ratio (copolymerization ratio) of the monomers (1 ′) to (6 ′) in synthesizing the polymer (1) can be appropriately set depending on the desired composition of the polymer (1). For example, the copolymerization ratio of the monomer (1 ′) is preferably 1% by weight or more, more preferably 1 to 60% by weight, still more preferably 2 to 40% by weight, particularly preferably based on the total amount of the monomers. Is in the range of 3 to 30% by weight. By setting the copolymerization ratio of the monomer (1 ′) within this range, it is possible to impart good pretilt angle expression to the obtained liquid crystal alignment film.
The copolymerization ratio of the monomer (2 ′) is preferably 50% by weight or less, more preferably 5 to 50% by weight, still more preferably 15 to 45% by weight, particularly preferably 20 based on the total amount of monomers. It is in the range of ˜40% by weight. By setting the copolymerization ratio of the monomer (2 ′) within this range, it is possible to improve the film density of the obtained liquid crystal alignment film, thereby diffusing impurity ions contained in the liquid crystal into the liquid crystal alignment film. Can be further reduced, and seizure of the liquid crystal display element can be further suppressed.
The copolymerization ratio of the monomer (3 ′) is preferably 50% by weight or less, more preferably 5 to 50% by weight, still more preferably 7 to 45% by weight, particularly preferably 10 based on the total amount of the monomers. It is in the range of ˜40% by weight. The copolymerization ratio of the monomer (3 ′) is preferably approximately the same as the copolymerization ratio of the monomer (2 ′).
The copolymerization ratio of the monomer (4 ′) is preferably 30% by weight or less, more preferably 1 to 30% by weight, and further preferably 2 to 20% by weight based on the total amount of the monomers.
The copolymerization ratio of the monomer (5 ′) is preferably 30% by weight or less, more preferably 1 to 30% by weight, and further preferably 2 to 20% by weight based on the total amount of the monomers.
The copolymerization ratio of the monomer (6 ′) is preferably 50% by weight or less, more preferably 40% by weight or less, and further preferably 30% by weight or less based on the total amount of the monomers.

Examples of the solvent used for the synthesis of the polymer (1) include alcohol, ether, glycol ether, ethylene glycol alkyl ether acetate, diethylene glycol alkyl ether, propylene glycol monoalkyl ether, propylene glycol alkyl ether acetate, propylene glycol alkyl ether propio. Nates, aromatic hydrocarbons, ketones, esters and the like.
Specific examples thereof include alcohols such as methanol, ethanol, benzyl alcohol, 2-phenylethyl alcohol, and 3-phenyl-1-propanol;
Tetrahydrofuran, di-n-amyl ether, etc. as ether; Glycol ether, eg, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, etc .; Ethylene glycol alkyl ether acetate, eg, methyl cellosolve acetate, ethyl cellosolve acetate, ethylene glycol monobutyl ether acetate , Ethylene glycol monoethyl ether acetate, etc .;
Diethylene glycol alkyl ethers such as diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol ethyl methyl ether and the like; propylene glycol monoalkyl ethers such as propylene glycol monomethyl ether, propylene glycol monoethyl ether and propylene glycol mono Propyl ether, propylene glycol monobutyl ether, etc .;
As propylene glycol alkyl ether propionate, for example, propylene glycol methyl ether propionate, propylene glycol ethyl ether propionate, propylene glycol propyl ether propionate, propylene glycol butyl ether propionate, etc .;
Examples of propylene glycol alkyl ether acetates include propylene glycol methyl ether acetate, propylene glycol ethyl ether acetate, propylene glycol propyl ether acetate, propylene glycol butyl ether acetate;
Aromatic hydrocarbons such as toluene, xylene, etc .;
Examples of ketones include methyl ethyl ketone, cyclohexanone, 4-hydroxy-4-methyl-2-pentanone, diisobutyl ketone and the like;

Examples of esters include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, methyl hydroxyacetate, hydroxy Ethyl acetate, hydroxybutyl acetate, methyl lactate, ethyl lactate, propyl lactate, butyl lactate, methyl 3-hydroxypropionate, ethyl 3-hydroxypropionate, propyl 3-hydroxypropionate, butyl 3-hydroxypropionate, 2-hydroxy -3-methylbutanoate, methyl methoxyacetate, ethyl methoxyacetate, propyl methoxyacetate, butyl methoxyacetate, methyl ethoxyacetate, ethyl ethoxyacetate, propyl ethoxyacetate, butyl ethoxyacetate, propoxy Methyl acetate, ethyl propoxyacetate, propyl propoxyacetate, butyl propoxyacetate, methyl butoxyacetate, ethyl butoxyacetate, propyl butoxyacetate, butylbutoxyacetate, methyl 2-methoxypropionate, ethyl 2-methoxypropionate, 2-methoxypropionic acid Propyl, butyl 2-methoxypropionate, methyl 2-ethoxypropionate, ethyl 2-ethoxypropionate, propyl 2-ethoxypropionate, butyl 2-ethoxypropionate, methyl 2-butoxypropionate, ethyl 2-butoxypropionate Propyl 2-butoxypropionate, butyl 2-butoxypropionate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, propyl 3-methoxypropionate, 3-methoxypropyl Butyl pionate, methyl 3-ethoxypropionate, ethyl 3-ethoxypropionate, propyl 3-ethoxypropionate, butyl 3-ethoxypropionate, methyl 3-propoxypropionate, ethyl 3-propoxypropionate, 3-propoxypropionate Examples thereof include propyl acid, butyl 3-propoxypropionate, methyl 3-butoxypropionate, ethyl 3-butoxypropionate, propyl 3-butoxypropionate, and butyl 3-butoxypropionate.

Of these, ethylene glycol alkyl ether acetate, diethylene glycol alkyl ether, propylene glycol monoalkyl ether, and propylene glycol alkyl ether acetate are preferable. Particularly, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol. Methyl ether acetate or methyl 3-methoxypropionate is preferred.
As the polymerization initiator used for the synthesis of the polymer (1), those generally known as radical polymerization initiators can be used. For example, 2,2′-azobisisobutyronitrile, 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobis- (4-methoxy-2,4-dimethylvaleronitrile) Azo compounds such as; benzoyl peroxide, lauroyl peroxide, t-butyl peroxypivalate, organic peroxides such as 1,1′-bis- (t-butylperoxy) cyclohexane; and hydrogen peroxide. When a peroxide is used as the radical polymerization initiator, the peroxide may be used together with a reducing agent to form a redox initiator.
In the synthesis of the polymer (1), a molecular weight modifier can be used to adjust the molecular weight of the polymer (1). Specific examples thereof include halogenated hydrocarbons such as chloroform and carbon tetrabromide; mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, tert-dodecyl mercaptan and thioglycolic acid; dimethylxanthogen sulfide, Xanthogens such as diisopropylxanthogen disulfide; terpinolene, α-methylstyrene dimer and the like.

In the synthesis of the polymer (1), the polymerization conditions (solvent species, solvent / monomer charge ratio), polymerization temperature, initiator species and addition amount thereof, molecular weight regulator type and addition amount thereof, and the like are appropriately adjusted. It is preferable to control to the above molecular weight range. Appropriate polymerization conditions for realizing the above molecular weight range can be easily estimated by a person skilled in the art by performing a few preliminary experiments.
A polymer solution containing the polymer (1) is obtained as described above. This polymer solution may be used as it is for the preparation of the liquid crystal aligning agent, or may be used for the preparation of the liquid crystal aligning agent after the polymer (1) contained in the polymer solution is isolated or isolated. You may use for preparation of a liquid crystal aligning agent, after refine | purifying a polymer (1). The polymer (1) is isolated by pouring the polymer solution into a large amount of a poor solvent to obtain a precipitate, and drying the precipitate under reduced pressure, or distilling the polymer solution under reduced pressure using an evaporator. It can be done by a method. Further, the polymer (1) can be obtained by dissolving the isolated polymer (1) again in an organic solvent and then precipitating with a poor solvent, or by performing the step of evaporating under reduced pressure with an evaporator once or several times. Can be purified.

<Polyamic acid>
The polyamic acid that can be used in the present invention can be obtained by reacting a tetracarboxylic dianhydride with a diamine.
[Tetracarboxylic dianhydride]
Examples of the tetracarboxylic dianhydride used for the synthesis of the polyamic acid include butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1, 2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dichloro-1,2,3,4- Cyclobutanetetracarboxylic dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3 ′, 4,4′-dicyclohexyltetracarboxylic dianhydride, 2,3,5-tricarboxycyclo Ntylacetic acid dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1,3,3a, 4,5,9b -Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro- 5-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro- 5-ethyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro -7-methyl-5- (tetrahydro-2,5 -Dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-7-ethyl-5- (tetrahydro-2, 5-Dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2 , 5-Dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-ethyl-5- (tetrahydro- 2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5,8-dimethyl-5 (Tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2- ] -Furan-1,3-dione, 5- (2,5-dioxotetrahydrofuranyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, bicyclo [2,2,2] -oct -7-ene-2,3,5,6-tetracarboxylic dianhydride, 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 '-(tetrahydrofuran-2 ', 5'-dione), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy- 2-carboxynorbornane-2: 3,5: 6-dianhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10-tetraone, Formula (T-I) or (T-II)

(Wherein R ¹ and R ³ each represents a divalent organic group having an aromatic ring, R ² and R ⁴ each represent a hydrogen atom or an alkyl group, and a plurality of R ² and R ^{4 are present.} May be the same or different.)
Aliphatic and alicyclic tetracarboxylic dianhydrides such as compounds represented by:
Pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 1,4,5, 8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride, 3,3 ′, 4,4′-tetraphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic dianhydride 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, 4,4′-bis ( 3,4-dicar Boxyphenoxy) diphenylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidene diphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2 , 2 ′, 3,3′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis ( Triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4′-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4′-diphenylmethane dianhydride, ethylene glycol-bis ( Anhydrotrimellitate), propylene glycol-bis (anhydrotrimellitate), 1,4-butanediol-bis (anhydrotrimellitate) Retate), 1,6-hexanediol-bis (anhydrotrimellitate), 1,8-octanediol-bis (anhydrotrimellitate), 2,2-bis (4-hydroxyphenyl) propane-bis ( Anhydrotrimellitate), the following formulas (T-1) to (T-3)

And aromatic tetracarboxylic dianhydrides such as compounds represented by each of the above. These may be used alone or in combination of two or more.
Among tetracarboxylic dianhydrides used in the synthesis of polyamic acid, among the above, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl- 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 1,3 , 3a, 4,5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4 , 5,9b-Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4 , 5,9b- Xahydro-5,8-dimethyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, bicyclo [2,2,2] -oct -7-ene-2,3,5,6-tetracarboxylic dianhydride, 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 '-(tetrahydrofuran-2 ', 5'-dione), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy- 2-carboxynorbornane-2: 3,5: 6-dianhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10-tetraone, pyro Mellitic dianhydride 3,3 ', 4,4'-benzofu Non-tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 2,3 ′, 2,3′-biphenyltetracarboxylic dianhydride, 1,4,5 , 8-Naphthalenetetracarboxylic dianhydride, among the compounds represented by the above formula (TI), the following formulas (T-4) to (T-6)

Of the compound represented by each of the above and the compound represented by the above formula (T-II), the following formula (T-7)

It is possible to develop good liquid crystal alignment properties including at least one selected from the group consisting of the compounds represented by (hereinafter referred to as “specific tetracarboxylic dianhydride (1)”). It is preferable from the viewpoint. Particularly preferred specific tetracarboxylic dianhydrides (1) are 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl- 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1, 2-c] furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1, 2-c] furan-1,3-dione, 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 ′-(tetrahydrofuran-2 ′, 5′-dione), 5- (2,5-Dioxotetra Dro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxynorbornane-2: 3,5: 6-dianhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10-tetraone and at least one selected from the group consisting of pyromellitic dianhydride .
The tetracarboxylic dianhydride used for the synthesis of polyamic acid should contain 30 mol% or more of the specific tetracarboxylic dianhydride (1) as described above with respect to the total tetracarboxylic dianhydride. Preferably, it contains 50 mol% or more.

[Diamine]
Examples of the diamine used for the synthesis of the polyamic acid include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenyl sulfide, 4 , 4′-diaminodiphenylsulfone, 3,3′-dimethyl-4,4′-diaminobiphenyl, 4,4′-diaminobenzanilide, 4,4′-diaminodiphenyl ether, 1,5-diaminonaphthalene, 2,2 '-Dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 2,2'-ditrifluoromethyl-4,4'-diaminobiphenyl, 3,3'-ditri Fluoromethyl-4,4′-diaminobiphenyl, 5-amino-1- (4′-aminophenyl) -1,3,3-to Methylindane, 6-amino-1- (4′-aminophenyl) -1,3,3-trimethylindane, 3,4′-diaminodiphenyl ether, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2- Bis (4-aminophenyl) hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] sulfone, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4- Aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) -10-hydride Anthracene, 2,7-diaminofluorene, 9,9-dimethyl-2,7-diaminofluorene, 9,9-bis (4-aminophenyl) fluorene, 4,4′-methylene-bis (2-chloroaniline), 2,2 ′, 5,5′-tetrachloro-4,4′-diaminobiphenyl, 2,2′-dichloro-4,4′-diamino-5,5′-dimethoxybiphenyl, 3,3′-dimethoxy- 4,4′-diaminobiphenyl, 1,4,4 ′-(p-phenyleneisopropylidene) bisaniline, 4,4 ′-(m-phenyleneisopropylidene) bisaniline, 2,2′-bis [4- (4- Amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, 4,4′-bis [(4-amino 2-trifluoromethyl) phenoxy] - aromatic diamines such as octafluoro biphenyl;

2,3-diaminopyridine, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 5,6-diamino-2,3-dicyanopyrazine, 5,6-diamino-2,4 -Dihydroxypyrimidine, 2,4-diamino-6-dimethylamino-1,3,5-triazine, 1,4-bis (3-aminopropyl) piperazine, 2,4-diamino-6-isopropoxy-1,3 , 5-triazine, 2,4-diamino-6-methoxy-1,3,5-triazine, 2,4-diamino-6-phenyl-1,3,5-triazine, 2,4-diamino-6-methyl -S-triazine, 2,4-diamino-1,3,5-triazine, 4,6-diamino-2-vinyl-s-triazine, 2,4-diamino-5-phenylthiazole, 2,6- Aminopurine, 5,6-diamino-1,3-dimethyluracil, 3,5-diamino-1,2,4-triazole, 6,9-diamino-2-ethoxyacridine lactate, 3,8-diamino-6 Phenylphenanthridine, 1,4-diaminopiperazine, 3,6-diaminoacridine, bis (4-aminophenyl) phenylamine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N-ethyl -3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, N, N'-di (4-aminophenyl) -benzidine, the following formula (DI)

(In the formula (DI), R ⁵ represents a monovalent organic group having a ring structure containing a nitrogen atom selected from the group consisting of pyridine, pyrimidine, triazine, piperidine and piperazine, and X ¹ represents a divalent organic group. R ⁶ represents an alkyl group having 1 to 4 carbon atoms, and a1 represents an integer of 0 to 3).
A compound represented by formula (D-II):

(In formula (D-II), R ⁷ represents a divalent organic group having a ring structure containing a nitrogen atom selected from the group consisting of pyridine, pyrimidine, triazine, piperidine and piperazine, and X ² represents 2 A plurality of X ² may be the same or different, R ⁸ represents an alkyl group having 1 to 4 carbon atoms, and a2 represents an integer of 0 to 3, respectively. Show.)
A diamine having two primary amino groups and a nitrogen atom other than the primary amino group in the molecule, such as a compound represented by:
1,3-bis (aminomethyl) cyclohexane, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine 1,4-diaminocyclohexane, isophorone diamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoin danylene dimethylene diamine, tricyclo [6.2.1.0 ^2,7 ] -undecylenedimethyl diamine , Aliphatic or cycloaliphatic diamines such as 4,4′-methylenebis (cyclohexylamine);
The following formula (D-III)

(In Formula (D-III), R ⁹ represents a hydrocarbon group having 1 to 12 carbon atoms, and a plurality of R ⁹ may be the same or different, and s represents 1 to 3 respectively. And t is an integer of 1 to 20.)
The diaminoorganosiloxane represented by these can be mentioned. These diamines may be used alone or in combination of two or more.
The benzene ring of the aromatic diamine may be substituted with one or two or more alkyl groups having 1 to 4 carbon atoms (preferably a methyl group). R ⁶ and R ⁸ in the above formulas (DI) and (D-II) are each preferably a methyl group, and a1 and a2 are each preferably 0 or 1, and are preferably 0 It is more preferable.
Among the above, the diamine used for the synthesis of the polyamic acid used in the liquid crystal aligning agent of the present invention is p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 1,5- Diaminonaphthalene, 2,7-diaminofluorene, 4,4′-diaminodiphenyl ether, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2 , 2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 1,4-bis (4-aminophenoxy) benzene, 4,4 '-Bis (4-aminophenoxy) biphenyl, 4,4'-diamino-2,2'-bis (trifluoromethyl) Biphenyl, 4,4'-diamino-2,2'-dimethylbiphenyl, 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, the above formula (D- Of the compounds represented by I), the following formula (D-1)

Of the compounds represented by formula (D-II), the following formula (D-2)

Of the compounds represented by formula (1), 1,3-bis (aminomethyl) cyclohexane, 1,4-cyclohexanediamine, 4,4′-methylenebis (cyclohexylamine), and the compound represented by the above formula (D-III) Formula (D-3)

3,3 ′-(tetramethyldisiloxane-1,3-diyl) bis (propylamine), 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N-ethyl-3 , 6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, and N, N′-di (4-aminophenyl) -benzidine (hereinafter referred to as “specific diamine”). ) Is preferred.
Particularly preferred specific diamines include p-phenylenediamine, 4,4′-diaminodiphenylmethane, 2,7-diaminofluorene, 4,4′-diaminodiphenyl ether, 4,4′-diamino-2,2′-dimethylbiphenyl and It is at least one selected from the group consisting of 1,3-bis (aminomethyl) cyclohexane.
As the diamine used for the synthesis of the polyamic acid, the specific diamine as described above is preferably contained in an amount of 1 mol% or more, more preferably 10 mol% or more, based on the total diamine.

The liquid crystal aligning agent of the present invention can express a desired pretilt angle by adjusting the composition and content of the polymer (1) to an appropriate range. When used in a TN, STN, OCB, or VA type liquid crystal display element, a diamine having a pretilt angle manifestation site as a diamine used in the synthesis of a polyamic acid contained in a liquid crystal aligning agent or an imidized polymer thereof. It is also possible to control the pretilt angle of the obtained liquid crystal alignment film.
Examples of the diamine having such a pretilt angle expression site include the following formula (D-IV):

(In formula (D-IV), R ¹⁰ and R ¹¹ are each independently a hydrogen atom or a methyl group, R ¹² is a linear or branched alkyl group having 1 to 20 carbon atoms, R ¹³ and R ¹⁴ are each independently a divalent organic group.)
A compound represented by the following formula (D-V)

(In the formula (D-V), R ¹⁵ represents an oxygen atom, a sulfur atom, —CO—, —COO—, —OCO—, —NHCO—, —CONH— or a methylene group, and R ¹⁶ represents a cholestanyl skeleton or cholestenyl. A monovalent group having a skeleton, a monovalent group having a trifluoromethylphenyl group or a trifluoromethoxyphenyl group, or an alkyl group having 1 to 22 carbon atoms, and R ¹⁷ is an alkyl group having 1 to 4 carbon atoms. , A3 is an integer of 0-3.)
The compound etc. which are represented by these can be mentioned. These diamine compounds having a pretilt angle expression site are used singly or in combination of two or more.
R ¹⁷ in the above formula (D-V) is preferably a methyl group, a3 is preferably 0 or 1, and more preferably 0.
Specific examples of the compound represented by the above formula (D-IV) include, for example, the following formula (D-4) or (D-5)

Specific examples of the compound represented by the above formula (DV) include, for example, the following formulas (D-6) to (D-10):

The compounds represented by each of the above can be mentioned.
When the liquid crystal aligning agent of the present invention is used for a VA type liquid crystal display device, it exhibits excellent liquid crystal vertical alignment. It is preferable to use a compound represented by formula (D-6) to (D-10), and it is more preferable to use at least one selected from the compounds represented by formulas (D-6) to (D-10). It is preferable to use at least one of the compound represented by (D-6) and the compound represented by the above formula (D-7).
The usage-amount of the diamine which has a pretilt angle expression site | part becomes like this. Preferably it is 8-60 mol% with respect to all the diamine, More preferably, it is 9-50 mol%, Especially preferably, it is 10-40 mol%. In this case, the diamine having a pretilt angle expression site and the specific diamine may be used in combination, and the amount of the specific diamine used in this case is preferably 1 to 90 mol% with respect to the total diamine. Preferably it is 10-90 mol%.

[Synthesis of polyamic acid]
The ratio of the tetracarboxylic dianhydride and the diamine used in the polyamic acid synthesis reaction is such that the acid anhydride group of the tetracarboxylic dianhydride is 0.2 with respect to 1 equivalent of the amino group contained in the diamine. The ratio which becomes -2 equivalent is preferable, More preferably, it is the ratio which becomes 0.3-1.2 equivalent.
The polyamic acid synthesis reaction is preferably carried out in an organic solvent under a temperature condition of preferably -20 to 150 ° C, more preferably 0 to 100 ° C. The reaction time is preferably 0.1 to 100 hours, more preferably 1 to 50 hours.
The organic solvent that can be used here is not particularly limited as long as it can dissolve the produced polyamic acid. For example, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide And aprotic polar solvents such as dimethyl sulfoxide, γ-butyrolactone, tetramethylurea and hexamethylphosphortriamide; and phenolic solvents such as m-cresol, xylenol, phenol and halogenated phenol. The amount of the organic solvent used (a) is such that the total amount (b) of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 30% by weight with respect to the total amount (a + b) of the reaction solution. It is preferable that Here, when the organic solvent is used in combination with the poor solvent described below, the amount of the organic solvent used (a) should be understood as meaning the total amount of the organic solvent and the poor solvent. is there.

From the viewpoint of improving printability, the organic solvent is used in combination with alcohol, ketone, ester, ether, halogenated hydrocarbon, hydrocarbon, etc., which are poor solvents for polyamic acid at the time of polymerization, in such a range that the generated polyamic acid does not precipitate. can do. Specific examples of the poor solvent include, for example, methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, ethylene glycol monomethyl ether, ethyl lactate, butyl lactate, Acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, diethyl malonate, diethyl ether, ethylene glycol methyl ether, ethylene Glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n- Chill ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1 , 4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene, isoamylpropionate, isoamylisobutyrate, diisopentyl ether and the like.
When a poor solvent is used in combination with an organic solvent, the use ratio of the poor solvent can be appropriately set within a range in which the polyamic acid to be produced does not precipitate, but is preferably 70% by weight or less, more preferably based on the total solvent. Is 50% by weight or less.

  As described above, a reaction solution obtained by dissolving polyamic acid is obtained. This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, may be used for the preparation of the liquid crystal aligning agent after isolating the polyamic acid contained in the reaction solution, or the isolated polyamic acid was purified. You may use for preparation of a liquid crystal aligning agent. Polyamic acid can be isolated by pouring the reaction solution into a large amount of poor solvent to obtain a precipitate, and drying the precipitate under reduced pressure, or by distilling the reaction solution under reduced pressure using an evaporator. it can. The polyamic acid can be purified by a method of dissolving the polyamic acid again in an organic solvent and then precipitating with a poor solvent, or a method of performing the step of evaporating under reduced pressure with an evaporator once or several times.

<Imidized polymer>
The imidized polymer of polyamic acid that can be used in the present invention can be obtained by dehydrating and ring-closing the polyamic acid obtained as described above. The imidized polymer referred to here is a concept including a partially imidized product obtained by partially imidizing the polyamic acid and a completely imidized product obtained by imidizing 100%. It is called "union".
[Tetracarboxylic dianhydride]
Examples of the tetracarboxylic dianhydride used for the synthesis of the imidized polymer include the same compounds as the tetracarboxylic dianhydride used for the synthesis of the polyamic acid described above.
The tetracarboxylic dianhydride used for the synthesis of the imidized polymer contained in the liquid crystal aligning agent of the present invention is selected from the group consisting of alicyclic tetracarboxylic dianhydrides and pyromellitic dianhydrides. A tetracarboxylic dianhydride containing at least one (hereinafter referred to as “specific tetracarboxylic dianhydride (2)”) is preferred.

Particularly preferred specific tetracarboxylic dianhydride (2) is 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5 -Dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5 -Dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3'- (Tetrahydrofuran-2 ′, 5′-dione), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6 -Tricarboxy-2-carboxy Ruborunan -2: 3,5: selected from 6-dianhydride and 4,9-dioxatricyclo [5.3.1.0 ^{2, 6]} undecane -3,5,8,10- tetraone group consisting Is at least one kind.
The tetracarboxylic dianhydride used for the synthesis of the imidized polymer contains the specific tetracarboxylic dianhydride (2) in an amount of 30 mol% or more based on the total tetracarboxylic dianhydride. It is preferable that the content is 50 mol% or more.
[Diamine]
Examples of the diamine used for the synthesis of the imidized polymer include the same diamine as that used for the synthesis of the polyamic acid described above.

[Method for synthesizing imidized polymer]
The dehydration ring closure reaction of polyamic acid can be carried out by (i) heating the polyamic acid or (ii) dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydrating ring closure catalyst to this solution, and heating if necessary. It is done by the method to do.
The reaction temperature in the method (i) of heating the polyamic acid is preferably 50 to 300 ° C, more preferably 60 to 170 ° C. When the reaction temperature is less than 50 ° C., the dehydration ring-closing reaction does not proceed sufficiently, and when the reaction temperature exceeds 300 ° C., the molecular weight of the imidized polymer obtained may decrease. The reaction time is preferably 2 to 24 hours, more preferably 3 to 10 hours.
On the other hand, in the method (ii) of adding a dehydrating agent and a dehydrating ring-closing catalyst to the polyamic acid solution, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride is used as the dehydrating agent. Can do. It is preferable that the usage-amount of a dehydrating agent shall be 0.01-20 mol with respect to 1 mol of amic acid structures of a polyamic acid. Moreover, as a dehydration ring closure catalyst, tertiary amines, such as a pyridine, a collidine, a lutidine, a triethylamine, can be used, for example. However, it is not limited to these. The amount of the dehydration ring-closing catalyst used is preferably 0.01 to 10 mol with respect to 1 mol of the dehydrating agent used. In addition, as an organic solvent used for dehydration ring closure reaction, the organic solvent illustrated as what is used for the synthesis | combination of a polyamic acid can be mentioned. And the reaction temperature of dehydration ring closure reaction becomes like this. Preferably it is 0-180 degreeC, More preferably, it is 10-150 degreeC, Reaction time becomes like this. Preferably it is 2-8 hours, More preferably, it is 3-6 hours.

  The imidized polymer obtained in the above method (i) may be used for the preparation of a liquid crystal aligning agent as it is, or may be used for the preparation of a liquid crystal aligning agent after purifying the obtained imidized polymer. . On the other hand, in the method (ii), a reaction solution containing an imidized polymer is obtained. This reaction solution may be used as it is for the preparation of the liquid crystal aligning agent, or may be used for the preparation of the liquid crystal aligning agent after removing the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution. After separation, the liquid crystal aligning agent may be used for preparation, or the isolated imidized polymer may be purified and then used for preparation of the liquid crystal aligning agent. In order to remove the dehydrating agent and the dehydration ring closure catalyst from the reaction solution, for example, a method such as solvent replacement can be applied. Isolation and purification of the imidized polymer can be performed by performing the same operations as described above as the method for isolating and purifying the polyamic acid.

-Imidization rate of imidized polymer-
The imidation ratio in the imidized polymer used in the present invention is preferably 10 to 99%, more preferably 20 to 99%, and particularly preferably 45 to 99%. Here, the “imidization rate” is a numerical value representing the ratio of the number of imide ring structures as a percentage of the total number of amic acid structures and the number of imide ring structures in the imidized polymer. At this time, what is part of the imide ring is an isoimide ring is also included in the number of imide ring structures. Such imidization ratio, the imidized polymer, after preferably sufficiently dried, dissolved in a suitable deuterated solvent (e.g. deuterated dimethyl sulfoxide), at room temperature with tetramethylsilane as a reference substance ¹ H- It can obtain | require by the following numerical formula (A) from the result of having measured NMR.

Imidization rate (%) = (1-A ¹ / A ² × α) × 100 (A)

A ¹ : Peak area derived from protons of NH groups appearing in the vicinity of 10 ppm A ² : Peak area derived from other protons α: Other protons relative to one proton of NH group in the precursor (polyamic acid) of imidized polymer Number ratio

-End-modified polymer-
The polyamic acid or imidized polymer contained in the liquid crystal aligning agent of the present invention may be a terminal-modified type having a controlled molecular weight. By using the terminal-modified polymer, the coating properties of the liquid crystal aligning agent can be further improved without impairing the effects of the present invention. Such a terminal-modified polymer can be obtained by adding a molecular weight modifier to a polymerization reaction system when synthesizing a polyamic acid. Examples of molecular weight regulators include acid monoanhydrides, monoamine compounds, monoisocyanate compounds, and the like.
Examples of the acid monoanhydride include maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic anhydride, n -Hexadecyl succinic anhydride etc. can be mentioned. Examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-eicosylamine, etc. it can. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.
The use ratio of the molecular weight modifier is preferably 5 mol% or less, more preferably 2 mol% or less, based on the total tetracarboxylic dianhydride or total diamine.

-Solution viscosity-
The polyamic acid or its imidized polymer obtained as described above preferably has a solution viscosity of 500 to 10,000 mPa · s when it is made into a solution having a concentration of 20% by weight. More preferably, it has a solution viscosity of ˜7,000 mPa · s.
The solution viscosity (mPa · s) of the above polymer is E for a polymer solution having a concentration of 20% by weight prepared using a good solvent for the polymer (for example, N-methyl-2-pyrrolidone, γ-butyrolactone, etc.). It is a value measured at 25 ° C. using a mold rotational viscometer.
[Use ratio of polyamic acid and imidized polymer]
The use ratio of at least one polymer selected from the group consisting of a polyamic acid and an imidized polymer in the liquid crystal aligning agent of the present invention is the weight (W ¹ ) of the polymer (1), the polyamic acid and the imidized weight. The ratio to the total weight (W ² ) of the coalescence is preferably an amount such that W ¹ : W ² = 1: 99 to 90:10, and W ¹ : W ² = 2: 98 to 80:20. it is preferable that the amount, in particular ^{W 1: W 2 = 3:} 97~60: it is preferable that the 40 and qs.

<Other additives>
The liquid crystal alignment film of the present invention contains, as an essential component, at least one selected from the group consisting of the polymer (1) as described above and a polyamic acid and an imidized polymer thereof. May be contained. Examples of such other components include functional silane compounds and low molecular compounds having two or more epoxy groups in the molecule (hereinafter referred to as “epoxy compounds”). These functional silane compounds or epoxy compounds can be added to the liquid crystal aligning agent of the present invention in order to further improve the adhesion and electrical properties of the obtained liquid crystal aligning film to the substrate surface.
Examples of the functional silane compound include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl)- 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyl Trimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4 7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3,6-diazanonyl acetate, N- Benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, 3-glycid Examples thereof include xylpropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, and N-bis (oxyethylene) -3-aminopropyltriethoxysilane. When these functional silane compounds are used, the use ratio thereof is based on 100 parts by weight of the total amount of the polymer of the present invention (the total amount of the polymer (1), polyamic acid and imidized polymer; the same applies hereinafter). The amount is preferably 1 to 50 parts by weight, more preferably 2 to 40 parts by weight, and particularly preferably 3 to 20 parts by weight.

  The epoxy compound is distinguished from the case where the polymer (1) has a cyclic ether bond, and specifically refers to those having a molecular weight of less than 2,000. Examples of such epoxy compounds 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, and 1,6-hexane. Diol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl-2,4-hexanediol, N, N, N ′, N′— Tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-4, 4 ′ Diaminodiphenylmethane, N, N, N ', N'- tetraglycidyl -p- phenylenediamine, N, N-diglycidyl - benzylamine, N, N-diglycidyl - such as aminomethyl cyclohexane may be mentioned as preferred. When these epoxy compounds are used, the use ratio thereof is preferably 1 to 60 parts by weight, more preferably 5 to 40 parts by weight, particularly preferably 10 to 30 parts by weight based on 100 parts by weight of the polymer of the present invention. Parts by weight.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention is at least one selected from the group consisting of the polymer (1), polyamic acid and its imidized polymer as described above, and other additives optionally blended as necessary. Is preferably dissolved and contained in an organic solvent.
As an organic solvent which can be used for the liquid crystal aligning agent of this invention, the same thing as the solvent illustrated as what is used for the synthesis reaction of a polymer (1) can be mentioned.
Particularly preferable organic solvents used in the liquid crystal aligning agent of the present invention include N-methyl-2-pyrrolidone, γ-butyrolactone, γ-butyrolactam, N, N-dimethylformamide, N, N-dimethyl from the viewpoint of printability. Acetamide, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, butyl lactate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene Glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-butyl ether (butyl cellosolve), ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, diethyl Examples include lenglycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, isoamyl propionate, isoamyl isobutyrate, and diisopentyl ether. These can be used alone or in admixture of two or more.

A particularly preferable solvent composition in the liquid crystal aligning agent of the present invention is a composition obtained by combining the above-mentioned solvents, in which a solid component does not precipitate in the liquid crystal aligning agent, and the surface tension of the liquid crystal aligning agent is 25 to 40 mN / The composition is in the range of m.
The solid content concentration in the liquid crystal aligning agent of the present invention (the ratio of the total weight of components other than the solvent of the liquid crystal aligning agent to the total weight of the liquid crystal aligning agent) is selected in consideration of viscosity, volatility, etc., preferably 1 -50% by weight, more preferably 2-40% by weight, still more preferably 3-30% by weight. That is, the liquid crystal aligning agent of the present invention forms a coating film that becomes a liquid crystal aligning film by applying this to the substrate surface and removing the solvent, but when the solid content concentration is less than 1% by weight, In some cases, the film thickness of the coating film becomes too small to obtain a good liquid crystal alignment film. On the other hand, when the solid content concentration exceeds 50% by weight, it is difficult to obtain a good liquid crystal alignment film because the film thickness is excessive, and the viscosity of the liquid crystal aligning agent increases, resulting in poor coating characteristics. In some cases, a liquid crystal alignment film having excellent internal uniformity cannot be obtained.
Note that the particularly preferable range of the solid content concentration differs depending on the coating method used when the liquid crystal aligning agent is applied to the substrate, and more specifically, it is appropriate for the liquid crystal aligning agent to have an appropriate solution viscosity for each coating method. It is preferable to adjust to a certain solid concentration. For example, when the spinner method is used, the solution viscosity of the liquid crystal aligning agent is preferably adjusted to a range of 3.0 to 10.0 mPa · s. When using the printing method, it is preferable to adjust the solution viscosity of the liquid crystal aligning agent to a range of 12 to 50 mPa · s. In the case of the ink jet method, the solution viscosity of the liquid crystal aligning agent is preferably in the range of 3 to 15 mPa · s.
The temperature for preparing the liquid crystal aligning agent of the present invention is preferably 0 ° C to 200 ° C, more preferably 20 ° C to 60 ° C.

<Liquid crystal display element>
The liquid crystal display element of the present invention comprises a liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention as described above.
The liquid crystal display element of the present invention can be produced, for example, by the following method.
(1) First, the liquid crystal alignment film of the present invention is applied onto a pair of substrates, and the solvent is removed to form a coating film. Here, when the display mode of the liquid crystal display element to be manufactured is a vertical electric field system such as a TN type, an STN type, or a VA type, two substrates on which a transparent conductive film patterned on one side is provided. Are used as a pair of substrates. On the other hand, when the display mode of the liquid crystal display element to be manufactured is a horizontal electric field method, a pair of a substrate provided with a transparent conductive film having a comb-like pattern and a substrate not having a transparent conductive film is used. Used as a substrate.
In any of the above cases, the liquid crystal aligning agent is applied onto the substrate (on the surface having the transparent conductive film of the substrate when the substrate has a transparent conductive film). As the substrate, for example, glass such as float glass or soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, poly (cycloaliphatic olefin) can be used. Examples of the transparent conductive film provided on one surface of the substrate include an NESA film (registered trademark of PPG, USA) made of tin oxide (SnO ₂ ), an ITO film made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ), and the like. Can be used. In addition, in order to obtain these patterned transparent conductive films, a method of forming a pattern by a photo-etching method after forming a transparent conductive film without a pattern, and a mask having a desired pattern when forming the transparent conductive film. For example, a method of directly forming a patterned transparent conductive film can be employed.
The liquid crystal aligning agent is applied onto the substrate by an appropriate application method such as a roll coater method, a spinner method, a printing method, or an ink jet method. When applying the liquid crystal aligning agent, in order to further improve the adhesion between the substrate surface and the transparent conductive film and the coating film, a functional silane compound, a functional titanium compound, or the like is applied in advance to the coated surface of the substrate. You may keep it.

After the application, preheating (pre-baking) is preferably performed for the purpose of preventing dripping of the applied alignment agent. The pre-bake temperature is preferably 30 to 200 ° C, more preferably 40 to 150 ° C, and particularly preferably 40 to 100 ° C. The pre-bake time is preferably 0.5 to 10 minutes, more preferably 0.5 to 5 minutes. Thereafter, a baking (post-baking) step is performed for the purpose of completely removing the solvent. This Portobake is intended to completely remove the solvent from the coating film, and the polymer (1) contained in the liquid crystal aligning agent of the present invention has a cyclic ether structure represented by the above formula (2). When it has a repeating unit, it can also be carried out for the purpose of promoting the thermal crosslinking reaction of the cyclic ether structure. The post-baking temperature is preferably 80 to 300 ° C, more preferably 120 to 250 ° C. The post-bake time is preferably 5 to 180 minutes, more preferably 10 to 120 minutes.
Thus, the coating film used as a liquid crystal aligning film can be formed. The film thickness of the formed coating film is preferably 0.001-1 μm, more preferably 0.005-0.5 μm.
When the liquid crystal display element to which the liquid crystal aligning agent of the present invention is applied is a VA type liquid crystal display element, a projecting building as described in Patent Document 6 (Japanese Patent Application Laid-Open No. 2002-327058) is used. After forming on the substrate, a liquid crystal aligning agent may be applied to improve the viewing angle characteristics.

(2) When the display mode of the liquid crystal display element to be manufactured is the VA type, the coating film formed as described above can be used as a liquid crystal alignment film as it is. The rubbing process described may be performed. On the other hand, when the display mode of the liquid crystal display element to be manufactured is a vertical electric field method other than the VA type or a horizontal electric field method, a rubbing process is performed on the formed coating film surface.
The rubbing treatment can be performed by a method of rubbing in a certain direction with a roll around which a cloth made of fibers such as nylon, rayon, and cotton is wound. Thereby, the orientation ability of a liquid crystal molecule is provided to a coating film, and it becomes a liquid crystal aligning film. Furthermore, a part of the liquid crystal alignment film as shown in, for example, Patent Document 7 (Japanese Patent Laid-Open No. 6-222366) or Patent Document 8 (Japanese Patent Laid-Open No. 6-281937) is applied to the coating film after the rubbing treatment. Or a part of the surface of the liquid crystal alignment film as shown in Patent Document 9 (Japanese Patent Laid-Open No. 5-107544). By forming a resist film on the substrate and performing a rubbing treatment in a direction different from the previous rubbing treatment, and then removing the resist film, so that the liquid crystal alignment film has different liquid crystal alignment capabilities for each region, It is possible to improve the visibility characteristics of the obtained liquid crystal display element.

(3) A liquid crystal cell is manufactured by preparing two substrates on which a liquid crystal alignment film is formed as described above, and disposing a liquid crystal between the two substrates opposed to each other. Here, when the rubbing process is performed on the coating film, the two substrates are disposed to face each other so that the rubbing directions in the respective coating films are at a predetermined angle, for example, orthogonal or antiparallel.
In order to manufacture a liquid crystal cell, the following two methods are mentioned, for example.
The first method is a conventionally known method. First, two substrates are arranged to face each other through a gap (cell gap) so that the respective liquid crystal alignment films are opposed to each other, and the peripheral portions of the two substrates are bonded using a sealant, and the substrate surface and the sealant are bonded. A liquid crystal cell can be manufactured by injecting and filling liquid crystal into the cell gap partitioned by the step, and then sealing the injection hole.
The second method is a method called an ODF (One Drop Fill) method. For example, an ultraviolet light curable sealing material is applied to a predetermined location on one of the two substrates on which the liquid crystal alignment film is formed, and liquid crystal is dropped on the liquid crystal alignment film surface. The other substrate is bonded so as to face each other, and then the entire surface of the substrate is irradiated with ultraviolet light to cure the sealant, whereby a liquid crystal cell can be manufactured.
Regardless of which method is used, the liquid crystal cell produced as described above is further heated to a temperature at which the liquid crystal used takes an isotropic phase, and then gradually cooled to room temperature, so that the flow alignment during liquid crystal injection is achieved. It is desirable to remove.
And the liquid crystal display element of this invention can be obtained by bonding a polarizing plate on the outer surface of a liquid crystal cell.

Here, as the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used.
As the liquid crystal, for example, a nematic liquid crystal, a smectic liquid crystal, or the like can be used, and among these, a nematic liquid crystal is preferable. In the case of a VA liquid crystal cell, a nematic liquid crystal having negative dielectric anisotropy is preferable. For example, a dicyanobenzene liquid crystal, a pyridazine liquid crystal, a Schiff base liquid crystal, an azoxy liquid crystal, a biphenyl liquid crystal, or a phenylcyclohexane liquid crystal is used. It is done. In the case of a TN type liquid crystal cell or an STN type liquid crystal cell, a nematic type liquid crystal having positive dielectric anisotropy is preferable. For example, biphenyl type liquid crystal, phenyl cyclohexane type liquid crystal, ester type liquid crystal, terphenyl type liquid crystal, biphenyl cyclohexane type A liquid crystal, a pyrimidine liquid crystal, a dioxane liquid crystal, a bicyclooctane liquid crystal, a cubane liquid crystal, or the like is used. Examples of these liquid crystals include cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, and cholesteryl carbonate; chiral agents such as those sold under the trade names C-15 and CB-15 (Merck); p-decyloxybenzylidene Ferroelectric liquid crystals such as -p-amino-2-methylbutyl cinnamate may be further added and used.
As a polarizing plate bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film in which a polarizing film called an “H film” that absorbs iodine while stretching and aligning polyvinyl alcohol is sandwiched between protective films of cellulose acetate The polarizing plate which consists of itself can be mentioned.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
Measurement of the solution viscosity, weight average molecular weight and molecular weight distribution of the polymers in Examples and Comparative Examples, production of liquid crystal display elements, and evaluation of vertical alignment, voltage holding ratio and seizure resistance of the liquid crystal display elements were performed by the following methods. It was.
[Measurement of solution viscosity]
The solution viscosity (mPa · s) of the polymer was measured at 25 ° C. using an E-type rotational viscometer for the polymer solution shown in each synthesis example.
[Measurement of weight average molecular weight and molecular weight distribution]
The weight average molecular weight (Mw) and number average molecular weight (Mn) in terms of polystyrene were measured using gel permeation chromatography (GPC) under the following conditions to obtain the value of molecular weight distribution (Mw / Mn).
GPC measuring device: “HLC-8020” manufactured by Tosoh Corporation
Column: Columns TSK guardcolumn α, TSK gel α-M and TSK gel α-2500 manufactured by Tosoh Corporation are used in series. Solvent: 9.4 g of lithium bromide monohydrate with respect to 3 L of dimethylformamide Solution in which 1.7 g of phosphoric acid is dissolved Measurement temperature: 35 ° C.

[Manufacture of liquid crystal display elements]
The liquid crystal aligning agent prepared in each example or comparative example was applied on a transparent conductive film made of an ITO film provided on one surface of a glass substrate using a spinner, prebaked at 80 ° C. for 1 minute on a hot plate, and then cleaned in an oven A substrate having a film thickness of 60 nm on the transparent conductive film was obtained by post-baking at 200 ° C. for 1 hour in a nitrogen atmosphere. The substrate is rubbed once with a rubbing machine having a roll around which a rayon cloth is wound, with a roll rotation speed of 400 rpm, a stage moving speed of 30 mm / sec, and a hair foot pushing length of 0.4 mm. A liquid crystal alignment ability was imparted. Next, the substrate was ultrasonically cleaned in pure water for 1 minute, and then dried in a clean oven at 100 ° C. for 10 minutes to obtain a substrate having a liquid crystal alignment film. These operations were repeated to produce a pair (two) of substrates having a liquid crystal alignment film.
Next, after applying an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm to the outer edges of the surfaces having the liquid crystal alignment film of the substrate having the pair of liquid crystal alignment films, the liquid crystal alignment film surfaces face each other. The adhesive was cured by overlapping and pressing.
Next, after filling negative liquid crystal (MLC-2038, manufactured by Merck & Co., Inc.) into the gap between the substrates through the liquid crystal injection port, the liquid crystal injection port is sealed with an acrylic photo-curing adhesive, and polarizing plates are formed on both sides of the substrate. A vertical alignment type liquid crystal display element was manufactured by bonding together.
[Evaluation of vertical alignment]
With respect to the vertical alignment type liquid crystal display device manufactured as described above, the pretilt angle was measured with an anchoring strength measuring device “OMS-J3” manufactured by Chuo Seiki Co., Ltd.
[Evaluation of voltage holding ratio]
The liquid crystal display device manufactured as described above was applied with a voltage of 5 V at 60 ° C. with an application time of 60 microseconds and a span of 1,670 milliseconds, and then held for 1,670 milliseconds after release of the application. The rate was measured under an atmosphere of 60 ° C. The measuring device of voltage holding ratio used VHR-1 made by Toyo Corporation. The voltage holding ratio is “good” if the value of the voltage holding ratio is 97.5% or more, and “bad” if it is less than 97.5%.
[Evaluation of seizure resistance (measurement of residual DC voltage)]
After applying a DC voltage of 17 V to the liquid crystal display device manufactured as described above for 20 hours in an atmosphere of 100 ° C., the application of the voltage is released, and after relaxing in a room temperature environment for 15 minutes, The residual voltage (residual DC voltage) was obtained by the flicker elimination method. It can be determined that the smaller the value of the residual DC voltage is, the liquid crystal display element is excellent in seizure resistance. A liquid crystal display element having a residual DC voltage value of 500 mV or less can be said to have “good” seizure resistance, and if the residual DC voltage value is larger than 500 mV, it can be said to be “bad”.

Synthesis Example 1 (Synthesis of Compound (1 ′))
68 g of 4- (4′-n-pentylbicyclohexyl-4-yl) phenol was dissolved in 800 mL of dehydrated tetrahydrofuran (THF), 27 g of triethylamine was added, and 36 g of methacryloyl chloride was gradually added dropwise at room temperature for 3 hours. The reaction was carried out with stirring. After completion of the reaction, triethylamine hydrochloride was removed by filtration, THF was removed by distillation under reduced pressure, and then 400 mL of chloroform was added. This solution was washed with water, the organic layer was dried over magnesium sulfate, and then chloroform was removed by distillation under reduced pressure to obtain 65 g of the desired 4- (4′-n-pentylbicyclohexyl-4-yl) phenyl methacrylate. (Yield: 79%).
Synthesis Example 2 (Synthesis of polymer (1))
To a four-necked flask equipped with a stir bar, a three-way cock and a thermometer, 40 g (0.10 mol) of 4- (4′-pentylbicyclohexyl-4-yl) phenyl methacrylate obtained in Synthesis Example 1 as a monomer, 20 g (0.14 mol) of glycidyl methacrylate, 13 g (0.15 mol) of methacrylic acid, 7.0 g (0.067 mol) of styrene, 7.0 g (0.039 mol) of N-cyclohexylmaleimide and 2-hydroxyethylmeta 13 g (0.10 mol) of crelate was charged, 200 g of diethylene glycol ethyl methyl ether as a solvent, 4.5 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as a polymerization initiator, and α-as a molecular weight regulator. 2.0 g of methylstyrene dimer was added. This was bubbled in a nitrogen stream for about 10 minutes to replace the nitrogen in the system, and then reacted at 70 ° C. for 5 hours in a nitrogen atmosphere to obtain a solution containing 33% by weight of the polymer (1-1). Obtained. When the molecular weight of the polymer (1-1) was measured by GPC, Mw = 22,000 and Mw / Mn = 2.3, and no peak attributable to the residual monomer was observed.

Synthesis Example 3 (Synthesis of polyamic acid (1))
196 g (1.0 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride as tetracarboxylic dianhydride and 212 g (1 of 2,2′-dimethyl-4,4′-diaminobiphenyl as diamine compound) 0.0 mol) is dissolved in a mixed solvent consisting of 370 g of N-methyl-2-pyrrolidone and 3,300 g of γ-butyrolactone, and reacted at 40 ° C. for 3 hours, whereby 10% by weight of polyamic acid (PA-1) is obtained. About 4,070 g of the contained solution was obtained.
The solution viscosity of this polyamic acid solution was 160 mPa · s.
Synthesis Example 4 (Synthesis of polyamic acid (2))
1,2,3,4-cyclobutanetetracarboxylic dianhydride 98 g (0.50 mol) and pyromellitic dianhydride 109 g (0.50 mol) as tetracarboxylic dianhydride and 4,4 as diamine compound 198 g (1.0 mol) of '-diaminodiphenylmethane was dissolved in a mixed solvent consisting of 230 g of N-methyl-2-pyrrolidone and 2,060 g of γ-butyrolactone, reacted at 40 ° C. for 3 hours, then γ-butyrolactone 1 , 350 g was added to obtain about 4,040 g of a solution containing 10% by weight of polyamic acid (PA-2).
The solution viscosity of this polyamic acid solution was 125 mPa · s.
Synthesis Example 5 (Synthesis of polyamic acid (3))
109 g (0.50 mol) of pyromellitic dianhydride as tetracarboxylic dianhydride and 98 g (0.50 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 4,4 as diamine compound -200 g (1.0 mol) of diaminodiphenyl ether was dissolved in a mixed solvent consisting of 230 g of N-methyl-2-pyrrolidone and 2,060 g of γ-butyrolactone, reacted at 40 ° C. for 3 hours, γ-butyrolactone 1, By adding 350 g, about 4,040 g of a solution containing 10% by weight of polyamic acid (PA-3) was obtained.
The solution viscosity of this polyamic acid solution was 200 mPa · s.

Synthesis Example 6 (Synthesis of imidized polymer (1))
2,3,5-tricarboxycyclopentylacetic acid dianhydride 21 g (0.094 mol) as tetracarboxylic dianhydride and 9.2 g (0.085 mol) p-phenylenediamine as diamine compound and the above formula (D- 6) The compound represented by 4.9 g (0.0094 mol) is dissolved in 140 g of N-methyl-2-pyrrolidone (NMP) and reacted at 60 ° C. for 5 hours to contain 20% by weight of polyamic acid. A solution was obtained. The solution viscosity of this solution was 2,400 mPa · s.
To this polyamic acid solution, 325 g of NMP was added, and further 7.4 g of pyridine and 9.5 g of acetic anhydride were added, and dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration cyclization reaction, the solvent in the system was replaced with new NMP (by this solvent replacement operation, pyridine and acetic anhydride used for the dehydration cyclization reaction were removed from the system. The same applies hereinafter). A solution containing 15% by weight of an imidized polymer (PI-1) having a rate of about 51% was obtained.
A small amount of this imidized polymer solution was taken, diluted by adding NMP, and the solution viscosity measured as a solution having a polymer concentration of 7.7% by weight was 22 mPa · s.

Synthesis Example 7 (Synthesis of imidized polymer (2))
19 g (0.085 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride and 7.3 g (0.068 mol) of p-phenylenediamine as a diamine compound and the above formula (D- A polymer containing polyamic acid by dissolving 8.9 g (0.017 mol) of the compound represented by 6) in 140 g of N-methyl-2-pyrrolidone (NMP) and reacting at 60 ° C. for 5 hours. A solution was obtained. A small amount of this solution was collected, and NMP was added thereto, and the solution viscosity measured as a solution having a polymer concentration of 20% by weight was 2,200 mPa · s.
325 g of NMP was added to this polyamic acid solution, 7.3 g of pyridine and 9.4 g of acetic anhydride were further added, and a dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration ring closure reaction, the solvent in the system was replaced with new NMP to obtain a solution containing 15% by weight of an imidized polymer (PI-2) having an imidization ratio of about 50%.
A small amount of this imidized polymer solution was taken, diluted by adding NMP, and the solution viscosity measured as a solution having a polymer concentration of 7.7% by weight was 22 mPa · s.

Synthesis Example 8 (Synthesis of imidized polymer (3))
21 g (0.094 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride and 9.2 g (0.085 mol) of p-phenylenediamine as a diamine compound and the above formula (D- 7) Compound 4.7 g (0.0095 mol) represented by N-methyl-2-pyrrolidone (NMP) is dissolved in 140 g and reacted at 60 ° C. for 5 hours to contain 20% by weight of polyamic acid. A solution was obtained. The solution viscosity of this solution was 5,800 mPa · s.
325 g of NMP was added to this polyamic acid solution, 7.4 g of pyridine and 9.6 g of acetic anhydride were further added, and dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration ring closure reaction, the solvent in the system was replaced with new NMP to obtain a solution containing 15% by weight of an imidized polymer (PI-3) having an imidization ratio of about 53%.
A small amount of this imidized polymer solution was taken, diluted by adding NMP, and the solution viscosity measured as a solution having a polymer concentration of 7.5% by weight was 40 mPa · s.

Synthesis Example 9 (Synthesis of imidized polymer (4))
19 g (0.085 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride and 7.4 g (0.068 mol) of p-phenylenediamine as a diamine compound and the above formula (D- 7) The compound represented by 8.5) (0.017 mol) is dissolved in 140 g of N-methyl-2-pyrrolidone (NMP) and reacted at 60 ° C. for 5 hours to contain 20% by weight of polyamic acid. A solution was obtained. The solution viscosity of this solution was 5,300 mPa · s.
325 g of NMP was added to this polyamic acid solution, 6.7 g of pyridine and 8.7 g of acetic anhydride were further added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the dehydration ring closure reaction, the solvent in the system was replaced with new NMP to obtain a solution containing 15% by weight of an imidized polymer (PI-4) having an imidization ratio of about 51%.
A small amount of this imidized polymer solution was taken, diluted by adding NMP, and the solution viscosity measured as a solution having a polymer concentration of 7.5% by weight was 39 mPa · s.

Synthesis Example 10 (Synthesis of imidized polymer (5))
20 g (0.089 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride and 6.8 g (0.063 mol) of p-phenylenediamine as a diamine compound, the above formula (D- 6) 4.7 g (0.0090 mol) of the compound represented by 4) and 4,4′-diaminodiphenylmethane 3.6 g (0.018 mol) are dissolved in 140 g of N-methyl-2-pyrrolidone (NMP). By reacting at 4 ° C. for 4 hours, a solution containing 20% by weight of polyamic acid was obtained. The solution viscosity of this solution was 2,400 mPa · s.
325 g of NMP was added to this polyamic acid solution, 14 g of pyridine and 18 g of acetic anhydride were further added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system was replaced with new γ-butyrolactone to obtain a solution containing 15% by weight of an imidized polymer (PI-5) having an imidation ratio of about 78%.
A small amount of this imidized polymer solution was taken, diluted by adding γ-butyrolactone, and the solution viscosity measured as a solution having a polymer concentration of 6.5% by weight was 21 mPa · s.

Comparative Synthesis Example 1 (Synthesis of Comparative Polymer)
A four-necked flask equipped with a stir bar, a three-way cock and a thermometer was charged with 40 g (0.28 mol) of glycidyl methacrylate, 20 g (0.23 mol) of methacrylic acid, 20 g (0.19 mol) of styrene and N- 20 g (0.11 mol) of cyclohexylmaleimide was added, 200 g of diethylene glycol ethyl methyl ether as a solvent, 4.5 g of 2,2′-azobis (2,4-dimethylvaleronitrile) as an initiator, and α-methyl as a molecular weight regulator. 2.0 g of styrene dimer was added. This was bubbled with a nitrogen stream for about 10 minutes to replace the nitrogen in the system, and then reacted at 70 ° C. for 5 hours in a nitrogen atmosphere, thereby containing 33% by weight of the comparative polymer (R-1). A solution was obtained.
When the molecular weight of the polymer (R-1) was measured by GPC, Mw = 22,000 and Mw / Mn = 2.4, and no peak attributable to the residual monomer was observed.

Example 1
A solution containing the polymer (1-1) obtained in Synthesis Example 2 and a solution containing the polyamic acid (PA-1) obtained in Synthesis Example 3 were combined with the polymer (1-1) / The polymer (PA-1) is mixed so that the weight ratio is 30/70, N-methyl-1-pyrrolidone (NMP) and butyl cellosolve are added thereto, and the solvent composition is NMP / butyl cellosolve / γ-butyrolactone / Diethylene glycol ethyl methyl ether = 23/50/25/2 (weight ratio), a solution having a solid content concentration of 3.5% by weight was obtained. After sufficiently stirring, this solution was filtered using a filter having a pore size of 0.2 μm. Thus, a liquid crystal aligning agent was prepared.
Using this liquid crystal aligning agent, evaluation was performed according to the above method. The evaluation results are shown in Table 1.
Example 2
A solution containing the polymer (1-1) obtained in Synthesis Example 2 and a solution containing the polyamic acid (PA-1) obtained in Synthesis Example 3 were combined with the polymer (1-1) / The polymer (PA-1) was mixed so that the weight ratio was 30/70, and N, N, N ′, N′-tetraglycidyl-m-xylenediamine was added to this as an epoxy compound in a total of 100 weight of the polymer. 10 parts by weight with respect to parts was added. N-methyl-1-pyrrolidone (NMP) and butyl cellosolve were further added thereto, and the solvent composition was NMP / butyl cellosolve / γ-butyrolactone / diethylene glycol ethyl methyl ether = 23/50/25/2 (weight ratio), solid content concentration Gave a 3.5 wt% solution. After sufficiently stirring this solution, a liquid crystal aligning agent was prepared by filtering using a filter having a pore size of 0.2 μm.
Using this liquid crystal aligning agent, evaluation was performed according to the above method. The evaluation results are shown in Table 1.

Examples 3-5, 9 and 12
In Example 1 above, a liquid crystal aligning agent was prepared and evaluated in the same manner as in Example 1 except that the types and amounts of the polymers used were as shown in Table 1.
The evaluation results are shown in Table 1.
Examples 6-8, 10, 11, 13-15 and Comparative Examples 1 and 2
In Example 2 above, the type and amount of polymer used and the amount of epoxy compound (N, N, N ′, N′-tetraglycidyl-m-xylenediamine) used were as shown in Table 1. A liquid crystal aligning agent was prepared and evaluated in the same manner as in Example 2.
The evaluation results are shown in Table 1.
Comparative Example 3
N-methyl-2-pyrrolidone (NMP) and butyl cellosolve are added to the solution containing the imidized polymer (PI-1) obtained in Synthesis Example 6 and diluted, and the solvent composition is NMP / butyl cellosolve = 50/50. (Weight ratio), a solution having a solid content concentration of 3.5% by weight. After sufficiently stirring this solution, a liquid crystal aligning agent was prepared by filtering using a filter having a pore size of 0.2 μm.
Using this liquid crystal aligning agent, evaluation was performed according to the above method. The evaluation results are shown in Table 1.
Comparative Example 4
N, N, N ′, N′-tetraglycidyl-m-xylenediamine was added as an epoxy compound to the solution containing the imidized polymer (PI-1) obtained in Synthesis Example 6 with respect to 100 parts by weight of the polymer. 5 parts by weight, and N-methyl-2-pyrrolidone (NMP) and butyl cellosolve are added thereto for dilution. The solvent composition is NMP / butyl cellosolve = 50/50 (weight ratio) and the solid content concentration is 3.5% by weight. Solution. After sufficiently stirring this solution, a liquid crystal aligning agent was prepared by filtering using a filter having a pore size of 0.2 μm.
Using this liquid crystal aligning agent, evaluation was performed according to the above method. The evaluation results are shown in Table 1.

Comparative Examples 5-7
In Comparative Example 4, a liquid crystal aligning agent was prepared and evaluated in the same manner as Comparative Example 4 except that the type of polymer and the amount of the epoxy compound used were as shown in Table 1.
The evaluation results are shown in Table 1.
Comparative Example 8
N, N, N ′, N′-tetraglycidyl-m-xylenediamine as an epoxy compound was added to the solution containing the imidized polymer (PI-5) obtained in Synthesis Example 16 with respect to 100 parts by weight of the polymer. 10 parts by weight, and γ-butyrolactone, N-methyl-2-pyrrolidone (NMP) and butyl cellosolve are added and diluted. The solvent composition is γ-butyrolactone / NMP / butyl cellosolve = 40/30/40 (weight ratio). ), A solution having a solid content concentration of 3.5% by weight. After sufficiently stirring this solution, a liquid crystal aligning agent was prepared by filtering using a filter having a pore size of 0.2 μm.
Using this liquid crystal aligning agent, evaluation was performed according to the above method. The evaluation results are shown in Table 1.

However, the abbreviations in the column of the solvent composition in Table 1 have the following meanings.
NMP: N-methyl-2-pyrrolidone BC: Butyl cellosolve (ethylene glycol monobutyl ether)
EDM: Diethylene glycol ethyl methyl ether γ-BL: γ-butyrolactone

In Table 1 above, it can be seen that the liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention can simultaneously realize excellent liquid crystal alignment regulating power (particularly vertical alignment), high voltage holding ratio and good seizure resistance. (Examples 1 to 15). On the other hand, the liquid crystal aligning film formed from the conventionally known liquid crystal aligning agent was not able to satisfy all the said characteristics simultaneously (Comparative Examples 1-8).
The liquid crystal display element of the present invention having the liquid crystal alignment film as described above exhibits an excellent liquid crystal alignment regulating force (particularly vertical alignment) and suppresses the accumulation of residual DC when a thermal stress is applied. This has the advantage that seizure is reduced.

Claims (9)

Following formula (1)

(In the formula (1), R ^I is a hydrogen atom or a methyl group, A ¹ is a single bond, a phenylene group, or the following formulas (A ¹ -1) to (A ¹ -5)

_{^{- (CH 2) k -O- *}} (A 1 -5)
(In the above formula, i is 0 or 2, respectively, j is 0 or 1, k is an integer of 1 to 6, and “*” is a bond attached thereto, respectively. Is bound to B ^1. )
B ¹ is an alkylphenyl group or an alkylcyclohexyl group having an alkyl group having 4 to 10 carbon atoms. )
A polymer having a repeating unit represented by:
A liquid crystal aligning agent comprising a polyamic acid obtained by reacting tetracarboxylic dianhydride and a diamine, and at least one polymer selected from the group consisting of imidized polymers thereof. The repeating unit represented by the above formula (1) is represented by the following formula (1-1):

2. The liquid crystal aligning agent according to claim 1, which is a repeating unit represented by: A polymer having a repeating unit represented by the above formula (1) is further represented by the following formula (2):

(In Formula (2), R ^II is a hydrogen atom or a methyl group, A ² is a single bond, a methylene group or an alkylene group having 2 to 10 carbon atoms, and B ² is a cyclic ether structure having 2 to 10 carbon atoms. A group having
The liquid crystal aligning agent of Claim 1 or 2 which is a polymer which also has a repeating unit represented by these. The formula (2) in the ^{B 2} is a group having a 1,2-epoxy structure or 1,3 epoxy structure, the liquid crystal aligning agent of claim 3. An alkylene group of ^{A 2} is a methylene group or a C2-10 in the formula (2), ^{B 2} is a group having a 1,2-epoxy structure, the liquid crystal aligning agent of claim 4. At least one polymer selected from the group consisting of polyamic acid and imidized polymer thereof is 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3 -Furanyl) -naphtho [1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3 -Furanyl) -naphtho [1,2-c] furan-1,3-dione, 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 '-(tetrahydrofuran-2) ', 5'- ON), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxynorbornane- 2: 3,5: 6-dianhydride, 4,9-dioxatricyclo [5.3.1.0 ^2,6 ] undecane-3,5,8,10-tetraone and pyromellitic dianhydride A tetracarboxylic dianhydride containing at least one selected from the group consisting of:
p-phenylenediamine, 4,4'-diaminodiphenylmethane, 2,7-diaminofluorene, 4,4'-diaminodiphenyl ether, 4,4'-diamino-2,2'-dimethylbiphenyl and 1,3-bis (amino A polyamic acid obtained by reacting a diamine containing at least one selected from the group consisting of (methyl) cyclohexane and at least one polymer selected from the group consisting of imidized polymers thereof. Liquid crystal aligning agent as described in any one of these. Diamine is represented by the following formula (D-V)

(In the formula (D-V), R ¹⁵ represents an oxygen atom, a sulfur atom, —CO—, —COO—, —OCO—, —NHCO—, —CONH— or a methylene group, and R ¹⁶ represents a cholestanyl skeleton or cholestenyl. A monovalent group having a skeleton, a monovalent group having a trifluoromethylphenyl group or a trifluoromethoxyphenyl group, or an alkyl group having 1 to 22 carbon atoms, and R ¹⁷ is an alkyl group having 1 to 4 carbon atoms. , A3 is an integer of 0-3.)
The liquid crystal aligning agent as described in any one of Claims 1-6 containing the compound represented by these.   The liquid crystal aligning film formed from the liquid crystal aligning agent as described in any one of Claims 1-7.   A liquid crystal display device comprising the liquid crystal alignment film according to claim 8.