JP2009157351A - Liquid crystal aligning agent and liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal aligning agent providing a liquid crystal alignment layer with superior durability with respect to prolonged thermal stress, and to provide a liquid crystal display element preventing degradation of display performance even if it is driven for a long period of time. <P>SOLUTION: The liquid crystal aligning agent contains a polyamic acid obtained by a reaction of tetracarboxylic acid dianhydride including 2,3,5-tricarboxycyclopentylacetic acid dianhydride and a diamine including a compound represented by a formula A, and at least one type of a polymer selected from a group comprising a polyamide comprised by carrying out dehydration cyclization of a polyamic acid. The liquid crystal display element includes the liquid crystal alignment layer formed from the liquid crystal aligning agent. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal aligning agent and a liquid crystal display element. More specifically, the present invention relates to a liquid crystal aligning agent that provides a liquid crystal aligning film having excellent heat resistance, and a liquid crystal display element that can be driven for a long time while suppressing display deterioration due to thermal stress.

Currently, as a liquid crystal display element, a liquid crystal alignment film is formed on the surface of a substrate on which a transparent conductive film is provided to form a liquid crystal display element substrate. A so-called TN type (twisted) in which a layer of a nematic liquid crystal having a property is formed into a sandwich cell and the major axis of liquid crystal molecules is continuously twisted by 90 ° from one substrate to the other. A TN liquid crystal display element having a (Nematic) liquid crystal cell is widely known. In addition, an STN (Super Twisted Nematic) type liquid crystal display element capable of realizing a high contrast ratio as compared with a TN type liquid crystal display element, an IPS (In-Plane Switching) type liquid crystal display element with less viewing angle dependency, and an IPS type electrode structure FFS (Fringe Field Switching) type liquid crystal display element with improved aperture by increasing the aperture ratio of the display element part, and VA (Vertical Alignment) type liquid crystal display element with less viewing angle dependency and high-speed response of the video screen An OCB (Optical Compensated Bend) type liquid crystal display element having excellent properties has been developed.
As materials for the liquid crystal alignment film in these liquid crystal display elements, resin materials such as polyamic acid, polyimide, polyamide, and polyester are known, and in particular, a liquid crystal alignment film made of polyamic acid or polyimide has heat resistance, mechanical strength, It has excellent affinity with liquid crystal and is used in many liquid crystal display elements (see, for example, Patent Documents 1 to 3).

Since the liquid crystal display element having a liquid crystal alignment film made of these resin materials has improved its performance to such an extent that it can be used for television applications, it is designed on the assumption that the service life will exceed 10 years. Compared with the use of a display element, driving for an extremely long time is required.
When a conventionally known liquid crystal display device is continuously driven for a long time (for example, 1,000 hours or more), there is a problem that the contrast of light and darkness of the device is lowered. This defect is considered to be caused by the thermal stress of the liquid crystal alignment film due to thermal stress due to long-time driving, resulting in a decrease in the voltage holding ratio of the liquid crystal. Therefore, there is a demand for a liquid crystal alignment film excellent in heat resistance that exhibits a stable voltage holding ratio even when the liquid crystal display element is driven for a long time. However, a liquid crystal alignment agent that provides such a liquid crystal alignment film is not yet known.
JP-A-9-197411 JP 2003-149648 A JP 2003-107486 A JP-A-6-222366 JP-A-6-281937 JP-A-5-107544

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal alignment film that provides a liquid crystal alignment film excellent in durability (heat resistance) and exhibiting a stable voltage holding ratio against a long-term thermal stress. It is to provide an agent.
Another object of the present invention is to provide a liquid crystal display element in which display performance (particularly contrast) does not deteriorate even when driven for a long time.
Still other objects and advantages of the present invention will become apparent from the following description.

According to the present invention, the object of the present invention is firstly as follows:
Tetracarboxylic dianhydride including 2,3,5-tricarboxycyclopentylacetic dianhydride, and the following formula (A)

It is achieved by a liquid crystal aligning agent containing at least one polymer selected from the group consisting of a polyamic acid obtained by reaction with a diamine containing a compound represented by formula (I) and a polyimide formed by dehydrating and ring-closing the polyamic acid.
The above object of the present invention is secondly,
This is achieved by a liquid crystal display element comprising a liquid crystal alignment film formed from the above liquid crystal aligning agent.

The liquid crystal aligning agent of the present invention can form a liquid crystal aligning film excellent in heat resistance, that is, a liquid crystal aligning film in which the liquid crystal aligning ability does not deteriorate even when a long-term heat stress is applied. The liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention can be suitably applied to various liquid crystal display elements.
The liquid crystal display element of the present invention having such a liquid crystal alignment film does not deteriorate in display performance even when driven for a long time. Therefore, the liquid crystal display element of the present invention can be effectively applied to various devices, such as watches, portable games, word processors, notebook computers, car navigation systems, camcorders, PDAs, digital cameras, cellular phones, various monitors. Used for display devices such as liquid crystal televisions.

Hereinafter, the present invention will be described in detail.
The liquid crystal aligning agent of the present invention is obtained by reacting a tetracarboxylic dianhydride containing 2,3,5-tricarboxycyclopentylacetic acid dianhydride with a diamine containing a compound represented by the above formula (A). And at least one polymer selected from the group consisting of polyimides obtained by dehydrating and ring-closing the polyamic acid.
<Polyamic acid>
The polyamic acid that can be contained in the liquid crystal aligning agent of the present invention includes a tetracarboxylic dianhydride including 2,3,5-tricarboxycyclopentylacetic dianhydride and a compound represented by the above formula (A). It is obtained by reacting with the diamine containing.

[Tetracarboxylic dianhydride]
The tetracarboxylic dianhydride used for synthesizing the polyamic acid contained in the liquid crystal aligning agent of the present invention includes 2,3,5-tricarboxycyclopentylacetic acid dianhydride.
As the tetracarboxylic dianhydride, only 2,3,5-tricarboxycyclopentylacetic acid dianhydride may be used alone or in combination with other tetracarboxylic dianhydrides.
Other tetracarboxylic dianhydrides that can be used in the present invention include, for example, alicyclic tetracarboxylic dianhydrides other than 2,3,5-tricarboxycyclopentylacetic acid dianhydride, aliphatic tetracarboxylic acids Mention may be made of dianhydrides and aromatic tetracarboxylic dianhydrides.
Specific examples of the alicyclic tetracarboxylic dianhydride other than the 2,3,5-tricarboxycyclopentylacetic acid dianhydride include, for example, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 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-cyclo Pentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3 ′, 4,4′-dicyclohexyltetracarboxylic dianhydride, cis-3,7-dibutylsilane Loocta-1,5-diene-1,2,5,6-tetracarboxylic dianhydride, 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2 -Dicarboxylic anhydride, 3,5,6-tricarbonyl-2-carboxynorbornane-2: 3,5: 6-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 ( Trahydro-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-c] -furan-1,3-dione, 5- (2,5-dioxotetrahydrofural) -3-methyl-3 -Cyclohexene-1,2-dicarboxylic dianhydride, 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), the following formula (TI) or (T-II)

(Wherein R ¹ and R ³ are each a divalent organic group having an aromatic ring, R ² and R ⁴ are each a hydrogen atom or an alkyl group, and a plurality of R ² and R ^{4 are present.} May be the same or different.)
The compound etc. which are represented by these can be mentioned.
Specific examples of the aliphatic tetracarboxylic dianhydride include butanetetracarboxylic dianhydride.
Specific examples of the aromatic tetracarboxylic dianhydride include, for example, 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'-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3 ', 4,4'-tetraphenylsilane tetracarboxylic dianhydride 1,2,3,4-furantetracarboxylic dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-di Carboxyphenoxy Diphenylsulfone dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidenediphthalic dianhydride, 3, 3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (tri Phenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4'-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4'-diphenylmethane dianhydride, ethylene glycol-bis (an Hydrotrimellitate), propylene glycol-bis (anhydrotrimellitate), 1,4-butanediol-bis (anhydro) Remellitate), 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-4)

And the like, and the like.
Other tetracarboxylic dianhydrides that can be used to synthesize the polyamic acid contained in the liquid crystal aligning agent of the present invention include alicyclics other than 2,3,5-tricarboxycyclopentylacetic acid dianhydride. Of the tetracarboxylic dianhydrides and aromatic tetracarboxylic dianhydrides, pyromellitic dianhydride and 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride (hereinafter referred to as pyromellitic dianhydride) And 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride may be collectively referred to as “specific aromatic tetracarboxylic dianhydride”)) Among them, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic acid Dianhydride, 1,2,3,4-tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 5- (2,5-dioxotetrahydrofural) -3-methyl-3- Cyclohexene-1,2-dicarboxylic dianhydride, cis-3,7-dibutylcycloocta-1,5-diene-1,2,5,6-tetracarboxylic dianhydride, 3,5,6-tri Carbonyl-2-carboxynorbornane-2: 3,5: 6-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-hexahydro-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 Among the compounds represented by -2,4-dione-6-spiro-3 '-(tetrahydrofuran-2', 5'-dione) and the above formula (TI), the following formulas (T-5) to (T -7)

Of the compounds represented by formula (T-II), the following formula (T-8)

A tetracarboxylic dianhydride containing at least one selected from the group consisting of a compound represented by the formula: pyromellitic dianhydride and 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride Is more preferable from the viewpoint of exhibiting good liquid crystal orientation, and more preferably 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutane. Tetracarboxylic dianhydride, 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 1,3,3a, 4,5 9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, cis-3,7-dibutylcycloocta-1,5 Diene-1,2,5,6-tetracarboxylic dianhydride, 3,5,6-tricarbonyl-2-carboxynorbornane-2: 3,5: 6-dianhydride, 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), a compound represented by the above formula (T-5), pyromellitic dianhydride And a tetracarboxylic dianhydride containing at least one selected from the group consisting of 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, particularly preferably 1,2,3,4-tetra Carboxylic dianhydride, 1,3,3a, 4,5 9b-Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, pyromellitic dianhydride and 2,2 A tetracarboxylic dianhydride containing at least one selected from the group consisting of ', 3,3'-biphenyltetracarboxylic dianhydride.
When the tetracarboxylic dianhydride includes a tetracarboxylic dianhydride other than the alicyclic tetracarboxylic dianhydride and the specific aromatic tetracarboxylic dianhydride, the alicyclic tetracarboxylic dianhydride and Preferred tetracarboxylic dianhydrides other than the specific aromatic tetracarboxylic dianhydride include, for example, butanetetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3, Examples thereof include 3 ′, 4,4′-biphenylsulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, and the like.
The tetracarboxylic acid dianhydride used for synthesizing the polyamic acid contained in the liquid crystal aligning agent of the present invention is 2,3,5-tricarboxycyclopentylacetic acid dianhydride to all tetracarboxylic acid dianhydrides. On the other hand, the content is preferably 50 mol% or more, more preferably 80 mol% or more.

[Diamine]
The diamine used for synthesizing the polyamic acid contained in the liquid crystal aligning agent of the present invention contains a compound represented by the above formula (A).
Preferable specific examples of the compound represented by the above formula (A) include 3,5-diaminobenzoic acid.
As the diamine, only the compound represented by the above formula (A) may be used alone, or the compound represented by the above formula (A) and another diamine may be used in combination.
Examples of other diamines that can be used in the present invention include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, and 4,4′-diaminodiphenyl sulfide. 4,4′-diaminodiphenyl sulfone, 3,3′-dimethyl-4,4′-diaminobiphenyl, 4,4′-diaminobenzanilide, 4,4′-diaminodiphenyl ether, 1,5-diaminonaphthalene, 2, , 2′-dimethyl-4,4′-diaminobiphenyl, 5-amino-1- (4′-aminophenyl) -1,3,3-trimethylindane, 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-hydroanthracene, 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] hexafluoro Propane, 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, 4,4′-bis [(4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl, di (4 -Aromatic diamines such as aminophenyl) benzidine;

1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1 , 4-diaminocyclohexane, isophorone diamine, tetrahydrodicyclopentadienylenediamine, tricyclo [6.2.1.0 ^2,7 ] -undecylene diamine, 4,4′-methylenebis (cyclohexylamine), 1,3 -Aliphatic and alicyclic diamines such as bis (aminomethyl) cyclohexane;
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, 1- (3,5-diaminophenyl) -3-decylsuccinimide, 1- (3 5-Diaminophenyl) -3-octadecylsuccinimide, the following formula (DI)

(In the formula (DI), R ⁵ is 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 is a divalent group. Organic group.)
A compound represented by formula (D-II):

(In formula (D-II), X ² is 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 R ⁶ is (It is a divalent organic group, and a plurality of X ² may be the same or different.)
A diamine having two primary amino groups and a nitrogen atom other than the primary amino group in a molecule such as a compound represented by:
The following formula (D-III)

(In the formula (D-III), R ⁷ is —O— ^* , —COO— ^* , —OCO— ^* , —NHCO— ^* , —CONH— ^* and —CO— ^* (provided with “*”). A bond is bonded to R ⁸ )), and R ⁸ has a skeleton or group selected from the group consisting of a steroid skeleton, a trifluoromethyl group, and a fluoro group It is a monovalent organic group or an alkyl group having 6 to 30 carbon atoms.)
A mono-substituted phenylenediamine represented by:
The following formula (D-IV)

(In the formula (D-IV), each 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 p is each 1 is an integer of 1 to 3, and q is an integer of 1 to 20.)
Diaminoorganosiloxanes such as compounds represented by:
The following formulas (D-1) to (D-5)

(Y in the formula (D-4) is an integer of 2 to 12, and z in the formula (D-5) is an integer of 1 to 5.)
The compounds represented by each of the above can be mentioned.
These diamines can be used alone or in combination of two or more.
Among these, p-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 2,7-diaminofluorene, 4,4′-diaminodiphenyl ether, 2, 2-bis [4- (4-aminophenoxy) phenyl] propane, 9,9-bis (4-aminophenyl) fluorene, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2 , 2-bis (4-aminophenyl) hexafluoropropane, 4,4 ′-(p-phenylenediisopropylidene) bisaniline, 4,4 ′-(m-phenylenediisopropylidene) bisaniline, 1,4-cyclohexanediamine 4,4′-methylenebis (cyclohexylamine), 1,4-bis (4-amino) Enoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, compounds represented by the above formulas (D-1) to (D-5), 2,6-diaminopyridine, 3,4- Of the compounds represented by diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, and the above formula (DI), the following formula (D-6)

  Of the compounds represented by formula (D-II), the following formula (D-7)

1,3-bis (-3-diaminopropyl) tetramethyldisiloxane is preferable among the compounds represented by formula (D-III) and the compound represented by formula (D-IV). In particular, p-phenylenediamine is preferred.
Among the compounds represented by the above formula (D-III), in the above formula (D-III), R ⁷ is —O— ^* or —COO— ^* (however, a bond marked with “*” is R ^8. And a compound in which R ⁸ is a monovalent organic group having a steroid skeleton is preferable, and the following formulas (D-8) to (D-16) are particularly preferable.

The compounds represented by each of these are preferred.
The diamine used for synthesizing the polyamic acid contained in the liquid crystal aligning agent of the present invention preferably contains 1 mol% or more of the compound represented by the above formula (A) with respect to the total diamine. More preferably, it contains 10 mol% or more. In addition to the compound represented by the above formula (A), the diamine used in the present invention is at least one selected from the group consisting of the compound represented by the above formula (D-III) and p-phenylenediamine. It is preferable that it is included. In this case, it is more preferable that the compound represented by the formula (D-III) is contained in an amount of 1 to 50 mol% based on the total diamine. Moreover, it is more preferable that 30 to 90 mol% of p-phenylenediamine is contained with respect to the total diamine.

[Synthesis of polyamic acid]
The polyamic acid contained in the liquid crystal aligning agent of the present invention includes a tetracarboxylic dianhydride including 2,3,5-tricarboxycyclopentylacetic acid dianhydride and a diamine including a compound represented by the above formula (A). It is obtained by reacting.
The ratio of the tetracarboxylic dianhydride and the diamine used in the polyamic acid synthesis reaction is 0.2 to 2 for the tetracarboxylic dianhydride acid anhydride group to 1 equivalent of the amino group of the diamine. The ratio which becomes an equivalent is preferable, More preferably, it is a ratio which becomes 0.7-1.2 equivalent.
The polyamic acid is preferably synthesized in an organic solvent, preferably at −20 ° C. to 150 ° C., more preferably at 0 to 100 ° C., preferably 1 to 72 hours, more preferably 3 to 48 hours. Done. Here, the organic solvent is not particularly limited as long as it can dissolve the produced polyamic acid. For example, 1-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, 3-butoxy Amide compounds such as -N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, 3-hexyloxy-N, N-dimethylpropanamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexa Examples include aprotic compounds such as methyl phosphortriamide; phenolic compounds such as m-cresol, xylenol, phenol, and halogenated phenol. The amount of organic solvent used (α) is usually such that the total amount (β) of tetracarboxylic dianhydride and diamine compound is 0.1 to 30% by weight based on the total amount of the reaction solution (α + β). It is preferable that Here, when the organic solvent is used in combination with the poor solvent described below, the amount (α) of the organic solvent refers to the total amount of the organic solvent and the poor solvent.

For the organic solvent, alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc., which are generally believed to be poor solvents for polyamic acids, may be used in combination as long as the resulting polyamic acid does not precipitate. Good. Specific examples of such poor solvents include, for example, methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, 4-hydroxy-4-methyl-2-pentanone, 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, malon Acid diethyl, diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-propyl ether, ethylene glycol-i Propyl ether, ethylene glycol-n-butyl 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, diisobutyl ketone, isoamylpropionate, isoamylisobutyrate , And the like di-iso-pentyl ether.
When the organic solvent and the poor solvent are used in combination, the amount of the poor solvent used can be appropriately set within a range in which the polyamic acid to be produced does not precipitate, but is preferably 30% by weight or less with respect to the total amount of the solvent. 20% by weight or less is more preferable.

  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.

<Polyimide>
The polyimide that can be contained in the liquid crystal aligning agent of the present invention can be obtained by dehydrating and ring-closing the polyamic acid as described above.
The polyimide contained in the liquid crystal aligning agent of the present invention may be a completely imidized product obtained by dehydrating and cyclizing all of the amic acid structure that the polyamic acid as a raw material had, and only a part of the amic acid structure is dehydrated. It may be a partially imidized product that is ring-closed and has both an amic acid structure and an imide ring structure.
The polyimide contained in the liquid crystal aligning agent of the present invention preferably has an imidation ratio of 40 mol% or more, and more preferably 80 mol% or more. By using a polyimide having an imidization ratio of 40 mol% or more, a liquid crystal aligning agent capable of forming a liquid crystal alignment film having a shorter afterimage erasing time can be obtained.
The said imidation rate represents the ratio which the number of the imide ring structure accounts with respect to the sum total of the number of the amic acid structures of polyimide, and the number of imide ring structures in percentage. At this time, a part of the imide ring may be an isoimide ring. The imidation rate is as follows from the result of measuring ¹ H-NMR at room temperature (for example, 25 ° C.) using tetramethylsilane as a reference substance by dissolving polyimide in a suitable deuterated solvent (for example, deuterated dimethyl sulfoxide). It can obtain | require by numerical formula (i).

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

(In Formula (i), A ¹ is a peak area derived from protons of NH groups appearing near a chemical shift of 10 ppm, A ² is a peak area derived from other protons, and α is a polyimide precursor (polyamic acid). The number ratio of other protons to one proton of NH group in

The dehydration ring closure of the polyamic acid is preferably performed by (i) a method of heating the polyamic acid, or (ii) dissolving the polyamic acid in an organic solvent, and adding a dehydrating agent and a dehydration ring closure catalyst to this solution as necessary. This is done by heating.
The reaction temperature in the method (i) of heating the polyamic acid is preferably 50 to 200 ° C, more preferably 60 to 170 ° C. The reaction time is preferably 1 to 8 hours, more preferably 3 to 5 hours. When the reaction temperature is less than 50 ° C., the dehydration ring-closing reaction does not proceed sufficiently, and when the reaction temperature exceeds 200 ° C., the molecular weight of the resulting polyimide may decrease.
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. Although the usage-amount of a dehydrating agent is based on the desired imidation rate, it is preferable to set it as 0.01-20 mol with respect to 1 mol of the amic acid structure 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. The imidation rate can be increased as the amount of the above dehydrating agent and dehydrating ring-closing agent increases. Examples of the organic solvent used in the dehydration ring-closing reaction include the organic solvents exemplified as those used for the synthesis of polyamic acid. The reaction temperature of the dehydration ring closure reaction is preferably 0 to 180 ° C, more preferably 10 to 150 ° C. The reaction time is preferably 1 to 8 hours, more preferably 3 to 5 hours.

    In the method (ii), a reaction solution containing polyimide is obtained as described above. This reaction solution may be used as it is for the preparation of a liquid crystal aligning agent, or may be used for the preparation of a liquid crystal aligning agent after removing the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution. It may be used for the preparation of a liquid crystal aligning agent or may be used for the preparation of a liquid crystal aligning agent after purifying the isolated polyimide. In order to remove the dehydrating agent and the dehydrating ring-closing catalyst from the reaction solution, for example, a method such as solvent replacement can be applied. The isolation and purification of the polyimide can be performed by performing the same operation as described above as the isolation and purification method of the polyamic acid.

-End-modified polymer-
The polyamic acid or polyimide contained in the liquid crystal aligning agent of the present invention may be of a terminal modified type whose molecular weight is adjusted. 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 regulator is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, based on 100 parts by weight of the total of tetracarboxylic dianhydride and diamine used when synthesizing the polyamic acid. is there.

-Solution viscosity-
The polyamic acid or polyimide obtained as described above preferably has a solution viscosity of 20 to 800 mPa · s, and a solution viscosity of 30 to 500 mPa · s when a 10% by weight solution is obtained. It is more preferable to have it.
The solution viscosity (mPa · s) of the polymer is a value measured at 25 ° C. using an E-type rotational viscometer for a polymer solution having a concentration of 10% by weight prepared using a good solvent for the polymer. .

<Other additives>
The vertical alignment type liquid crystal alignment film of the present invention contains, as an essential component, at least one selected from the group consisting of the polyamic acid as described above and a polyimide obtained by dehydrating and ring-closing the same, and other components as necessary. May be contained. Examples of such other components include other polymers and adhesion improvers.
These other polymers can be used to improve solution and electrical properties. Such other polymer is a polyamic obtained by reacting a tetracarboxylic dianhydride containing 2,3,5-tricarboxycyclopentylacetic acid dianhydride with a diamine containing a compound represented by the above formula (A). A polymer other than polyimide formed by dehydrating and ring-closing an acid and the polyamic acid, for example, tetracarboxylic dianhydride not containing 2,3,5-tricarboxycyclopentylacetic dianhydride and represented by the above formula (A) A polyamic acid (hereinafter referred to as “other polyamic acid”) obtained by reacting with a diamine that does not contain the compound, and a polyimide obtained by dehydrating and ring-closing the polyamic acid (hereinafter referred to as “other polyimide”). , Polyamic acid ester, polyester, polyamide, polysiloxane, cellulose derivative, polyacetal, polystyrene Derivatives, poly (styrene - phenylmaleimide) derivative, poly (meth) acrylate, and the like. Of these, other polymic acids or other polyimides are preferred.
As other polymer use ratios, the total polymer (tetracarboxylic dianhydride including the above 2,3,5-tricarboxycyclopentyl acetic dianhydride and the compound represented by the above formula (A)) may be used. The total of the polyamic acid obtained by reacting the diamine and the polyimide obtained by dehydrating and ring-closing the polyamic acid and other polymers. The same shall apply hereinafter.), Preferably 30% by weight or less, more preferably Is 20% by weight or less.

The said adhesive improvement agent can be used in order to improve the adhesiveness with respect to the substrate surface of the liquid crystal aligning film obtained. Examples of the adhesion improver include a compound having at least one epoxy group in the molecule (hereinafter referred to as “epoxy compound”), a functional silane compound, and the like.
Examples of the epoxy compound 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′-diame Diphenylmethane, 3- (N-allyl--N- glycidyl) aminopropyltrimethoxysilane, 3- (N, N- diglycidyl) and the like aminopropyltrimethoxysilane.
The use ratio of the epoxy compound as described above is preferably 40 parts by weight or less, more preferably 0.1 to 30 parts by weight with respect to 100 parts by weight of the total polymer.

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, N-bis ( Examples thereof include oxyethylene) -3-aminopropyltrimethoxysilane and N-bis (oxyethylene) -3-aminopropyltriethoxysilane.
The use ratio of the functional silane compound as described above is preferably 2 parts by weight or less, more preferably 0.01 to 0.2 parts by weight with respect to 100 parts by weight of the total polymer.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention preferably contains at least one selected from the group consisting of polyamic acid and polyimide as described above and other additives optionally blended as necessary, preferably dissolved in an organic solvent. Configured.
Examples of the organic solvent that can be 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-dimethylacetamide, 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, 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, 3-butoxy-N, N-dimethylpropanamide, 3-methoxy-N, N-dimethylpropanamide, 3-hexyloxy-N, N-dimethylpropanamide and the like can be mentioned.

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 appropriately selected in consideration of viscosity, volatility, and the like. The range is preferably 1 to 10% by weight. That is, the liquid crystal aligning agent of the present invention is applied to the substrate surface as described later, and preferably, when heated, a coating film that becomes a liquid crystal aligning film is formed, but the solid content concentration is less than 1% by weight. In this case, 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 10% by weight, the film thickness of the coating film becomes excessive. Thus, a good liquid crystal alignment film cannot be obtained, and the viscosity of the liquid crystal aligning agent increases, resulting in poor coating properties.
The particularly preferable range of the solid content concentration varies depending on the method used when the liquid crystal aligning agent is applied to the substrate. For example, when the spinner method is used, the solid content concentration is particularly preferably in the range of 1.5 to 4.5% by weight. In the case of the printing method, it is particularly preferable that the solid content concentration is in the range of 3 to 9% by weight, and thereby the solution viscosity is in the range of 12 to 50 mPa · s. In the case of the inkjet method, it is particularly preferable that the solid content concentration is in the range of 1 to 5% by weight, and thereby the solution viscosity is in the range of 3 to 15 mPa · s.
The temperature at the time of preparing the liquid crystal aligning agent of this invention becomes like this. Preferably it is 0 to 200 degreeC, More preferably, it is 20 to 60 degreeC.

<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.
As a preferable operation mode in the liquid crystal display element of the present invention, TN type, VA type or IPS type can be mentioned.
The liquid crystal display element of the present invention can be produced, for example, by the following steps (1) to (3). In the step (1), the substrate to be used, the preferred application method of the liquid crystal aligning agent, and the heating temperature after applying the liquid crystal aligning agent differ depending on the desired operation mode. Steps (2) and (3) are common to each operation mode.
(1) First, the liquid crystal aligning agent of this invention is apply | coated on a board | substrate, Then, a coating film is formed on a board | substrate by heating an application surface.
(1-1) When manufacturing a TN type or VA type liquid crystal display element, a pair of two substrates provided with a patterned transparent conductive film is used as a pair on the transparent conductive film forming surface of the present invention. The liquid crystal aligning agent is preferably applied by an offset printing method, a spin coating method, or an ink jet printing method, respectively, and then each coated surface is heated to form a coating film. Here, as the substrate, for example, a glass such as float glass or soda glass; a transparent substrate made of a plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, or poly (alicyclic olefin) can be used. As a transparent conductive film provided on one surface of the substrate, 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 ), etc. In order to obtain a patterned transparent conductive film which can be used, for example, a method of forming a pattern by photo-etching after forming a transparent conductive film without a pattern, a mask having a desired pattern when forming the transparent conductive film The method using can be used. 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 or functional titanium is formed on the surface of the substrate surface on which the coating film is to be formed. You may give the pretreatment which apply | coats a compound etc. previously.
The heating temperature after application of the liquid crystal alignment agent is preferably 30 to 300 ° C, more preferably 40 to 250 ° C, and the heating time is preferably 1 to 60 minutes, more preferably 10 to 30 minutes. The film thickness of the formed coating film is preferably 0.001-1 μm, more preferably 0.005-0.5 μm.

(1-2) On the other hand, when manufacturing an IPS type liquid crystal display element, the conductive film forming surface of the substrate provided with the comb-shaped transparent conductive film and the counter substrate provided with no conductive film On one surface, the liquid crystal aligning agent of the present invention is preferably applied by a roll coater method, a spinner method or an ink jet printing method, respectively, and then each coated surface is heated to form a coating film.
The material of the substrate and transparent conductive film used at this time, the patterning method of the transparent conductive film, and the pretreatment of the substrate are the same as in (1-1) above.
The heating temperature after applying the liquid crystal aligning agent is preferably 80 to 300 ° C, more preferably 120 to 250 ° C, and the heating time is preferably 1 to 60 minutes, more preferably 10 to 30 minutes. It is.
The preferable film thickness of the coating film to be formed is the same as (1-1) above.
In both cases (1-1) and (1-2), the liquid crystal aligning agent of the present invention forms a coating film that becomes an alignment film by removing the organic solvent after coating. In the case where the polymer contained in the agent is a polyamic acid or a polyimide having both an imide ring structure and an amic acid structure, the dehydration cyclization reaction proceeds by further heating after the coating film is formed, and is further imidized. It is good also as a coating film.

(2) Next, the rubbing process which rubs the coating-film surface formed as mentioned above in a fixed direction with the roll which wound the cloth which consists of fibers, such as nylon, rayon, cotton, for example is performed. Thereby, the orientation ability of a liquid crystal molecule is provided to a coating film, and it becomes a liquid crystal aligning film. In the case of a VA liquid crystal display element, the rubbing process may not be performed.
Further, for example, Patent Document 4 (Japanese Patent Laid-Open No. 6-222366) and Patent Document 5 (Japanese Patent Laid-Open No. 6-281937) show liquid crystal alignment films formed with the liquid crystal aligning agent of the present invention. A process for changing the pretilt angle of a part of the liquid crystal alignment film by irradiating a part of the liquid crystal alignment film with ultraviolet rays, as disclosed in Japanese Patent Application Laid-Open No. 5-107544 After a resist film is formed on a part of the liquid crystal alignment film surface, the resist film is removed after the rubbing process in a direction different from the previous rubbing process. It is possible to improve the visual field characteristics of the liquid crystal display element obtained by having it.

(3) The pair of substrates on which the liquid crystal alignment films are formed as described above are arranged to face each other through a gap (cell gap) so that the rubbing directions of the liquid crystal alignment films of the two substrates are orthogonal or antiparallel. Then, the peripheral portions of the two substrates are bonded using a sealing agent, liquid crystal is injected and filled into the cell gap defined by the substrate surface and the sealing agent, and the injection hole is sealed to form a liquid crystal cell. And a liquid crystal display element can be obtained by bonding a polarizing plate on the outer surface of a liquid crystal cell so that the polarization direction thereof coincides with or is orthogonal to the rubbing direction of a liquid crystal alignment film formed on each substrate. Here, as the sealing agent, for example, an epoxy resin containing a curing agent and aluminum oxide spheres as a spacer can be used. Examples of the liquid crystal include nematic liquid crystals and smectic liquid crystals. Among them, nematic liquid crystals are preferable. For example, Schiff base liquid crystals, azoxy liquid crystals, biphenyl liquid crystals, phenylcyclohexane liquid crystals, ester liquid crystals, terphenyl liquid crystals. Liquid crystals, biphenylcyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubane liquid crystals, and the like can be used. In addition, cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, and cholesteryl carbonate; chiral products such as those sold under the trade names “C-15” and “CB-15” (manufactured by Merck) Agent: Ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate may be added and used.
As a polarizing plate to be bonded to the outer surface of the liquid crystal cell, a polarizing film or an H film itself in which a polarizing film called “H film” in which iodine is absorbed while stretching and aligning polyvinyl alcohol is sandwiched between cellulose acetate protective films The polarizing plate which consists of can be mentioned.
The liquid crystal display element of the present invention manufactured as described above does not deteriorate in display performance even when it is continuously driven for a long time as compared with a conventionally known liquid crystal display element. Has an advantage that the light leakage of the backlight, which seems to be caused by the alignment failure of the liquid crystal due to the thermal deterioration of the liquid crystal alignment film, is not angry.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.
In the following synthesis examples, 3,5-diaminobenzoic acid used was a commercial product of Tokyo Chemical Industry Co., Ltd. as it was.
Moreover, the solution viscosity of the polymer in the synthesis example is a value measured at 25 ° C. using an E-type viscometer.
Synthesis Example 1 (Polyimide Synthesis Example 1)
2,3,5-tricarboxycyclopentyl acetic acid dianhydride 112 g (0.50 mol) and 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro) as tetracarboxylic dianhydride -2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3-dione 157 g (0.50 mol), p-phenylenediamine 83 g (0.78 mol) as diamine, 3, 15.2 g (0.10 mol) of 5-diaminobenzoic acid, 25 g (0.10 mol) of bisaminopropyltetramethyldisiloxane and 13 g (0.020 mol) of 3,6-bis (4-aminobenzoyloxy) cholestane In addition, 2.7 g (0.030 mol) of aniline as a monoamine was dissolved in 960 g of N-methyl-2-pyrrolidone and reacted at 60 ° C. for 6 hours. To obtain a polyamic acid solution by making. A small amount of the obtained polyamic acid solution was collected, and N-methyl-2-pyrrolidone was added, and the solution viscosity measured as a solution having a concentration of 10% by weight was 48 mPa · s.
Next, 2,700 g of N-methyl-2-pyrrolidone was added to the obtained polyamic acid solution, 396 g of pyridine and 409 g of acetic anhydride were added, and dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration ring-closing reaction, the solvent in the system is replaced with new γ-butyrolactone (in this operation, pyridine and acetic anhydride used for the dehydration ring-closing reaction were removed from the system. The same shall apply hereinafter) and further concentrated. As a result, about 2,640 g of a solution containing 15% by weight of polyimide (A-1) having an imidation ratio of about 90% was obtained.
A small amount of this solution was collected, and γ-butyrolactone was added to measure the solution viscosity as a solution having a concentration of 6.0% by weight of 15 mPa · s.

Synthesis Example 2 (Polyimide Synthesis Example 2)
224 g (1.0 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride, 76 g (0.7 mol) of p-phenylenediamine as diamine, 15 g of 3,5-diaminobenzoic acid (0.10 mol) and 105 g (0.20 mol) of the compound represented by the above formula (D-10) are dissolved in 4,500 g of N-methyl-2-pyrrolidone and reacted at 60 ° C. for 6 hours. A solution containing polyamic acid was obtained. A small amount of the obtained polyamic acid solution was collected and concentrated under reduced pressure, and the solution viscosity measured as a solution having a concentration weight of 10% was 60 mPa · s.
Next, 2,700 g of N-methyl-2-pyrrolidone was added to the obtained polyamic acid solution, 396 g of pyridine and 409 g of acetic anhydride were added, and dehydration ring closure reaction was performed at 110 ° C. for 4 hours. After the dehydration and cyclization reaction, the solvent in the system was replaced with new γ-butyrolactone, and further concentrated to obtain about 2, a solution containing 15% by weight of polyimide (A-2) having an imidization ratio of about 90%. 770 g was obtained.
A small amount of this solution was taken, and γ-butyrolactone was added to measure the solution viscosity as a solution having a concentration of 6.0% by weight of 16 mPa · s.

Synthesis Example 3 (Polyimide Synthesis Example 3)
77 g (0.34 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic anhydride and 19 g (0.18 mol) of p-phenylenediamine and 27 g of 3,5-diaminobenzoic acid as diamine ( 0.18 mol) was dissolved in 1,260 g of N-methyl-2-pyrrolidone and reacted at room temperature for 6 hours to obtain a solution containing polyamic acid. A small amount of the obtained polyamic acid solution was collected and concentrated under reduced pressure, and the solution viscosity measured as a solution having a concentration weight of 10% was 80 mPa · s.
Next, 600 g of N-methyl-2-pyrrolidone was added to the obtained polyamic acid solution, 136 g of pyridine and 105 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 γ-butyrolactone and further concentrated to obtain 600 g of a solution containing 20% by weight of polyimide (A-3) having an imidization ratio of about 85%. .
A small amount of this solution was collected, and γ-butyrolactone was added to measure the solution viscosity as a solution having a concentration of 6.0% by weight of 22 mPa · s.

Synthesis Example 4 (Polyimide Synthesis Example 4)
224 g (1.0 mol) of 2,3,5-tricarboxycyclopentyl acetic acid dianhydride as tetracarboxylic anhydride, 76 g (0.7 mol) of p-phenylenediamine as diamine, 24 g of 3,5-diaminobenzoic acid ( 0.1 mol), 23 g (0.1 mol) of 4,4′-diaminodiphenylmethane and 32 g (0.1 mol) of 2,2′-trifluoromethyl-4,4′-diaminobiphenyl were added to N-methyl-2 -A solution containing polyamic acid was obtained by dissolving in 2,700 g of pyrrolidone and reacting at room temperature for 6 hours. A small amount of the obtained polyamic acid solution was collected and concentrated under reduced pressure, and the solution viscosity measured as a solution having a concentration weight of 10% was 80 mPa · s.
Next, 2,000 g of N-methyl-2-pyrrolidone was added to the obtained polyamic acid solution, 150 g of pyridine and 200 g of acetic anhydride were added, and a dehydration ring closure reaction 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 and further concentrated to obtain 2,430 g of a solution containing 15% by weight of polyimide (A-4) having an imidization ratio of about 85%. Obtained.
A small amount of this solution was collected, and γ-butyrolactone was added to measure the solution viscosity as a solution having a concentration of 6.0% by weight of 20 mPa · s.

Synthesis Example 5 (Polyimide Synthesis Example 5)
66 g (0.29 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic anhydride and 50 g (0.33 mol) of 3,5-diaminobenzoic acid as diamine were added to N-methyl-2- A solution containing polyamic acid was obtained by dissolving in 1,260 g of pyrrolidone and reacting at room temperature for 6 hours. A small amount of the obtained polyamic acid solution was collected and concentrated under reduced pressure, and the solution viscosity measured as a solution having a concentration weight of 10% was 55 mPa · s.
Next, 600 g of N-methyl-2-pyrrolidone was added to the obtained polyamic acid solution, 116 g of pyridine and 90 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 γ-butyrolactone, and further concentrated to obtain about 760 g of a solution containing 15% by weight of polyimide (A-5) having an imidization ratio of about 85%. It was.
A small amount of this solution was collected, and γ-butyrolactone was added thereto, and the solution viscosity measured as a solution having a concentration of 6.0% by weight was 18 mPa · s.

Synthesis Example 6 (Synthesis Example 1 of other polyimide)
2,3,5-tricarboxycyclopentyl acetic acid dianhydride 112 g (0.50 mol) and 1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro) as tetracarboxylic dianhydride -2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3-dione 157 g (0.50 mol), p-phenylenediamine 94 g (0.88 mol) as diamine, bisamino 25 g (0.10 mol) of propyltetramethyldisiloxane and 13 g (0.020 mol) of 3,6-bis (4-aminobenzoyloxy) cholestane and 2.7 g (0.030 mol) of aniline as monoamine were added to N-methyl. A solution containing polyamic acid was obtained by dissolving in 960 g of 2-pyrrolidone and reacting at 60 ° C. for 6 hours. A small amount of the obtained polyamic acid solution was collected and concentrated under reduced pressure, and the solution viscosity measured as a solution having a concentration weight of 10% was 58 mPa · s.
2,700 g of N-methyl-2-pyrrolidone was added to the obtained polyamic acid solution, 396 g of pyridine and 409 g of acetic anhydride were added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the dehydration cyclization reaction, the solvent in the system was replaced with new γ-butyrolactone, and further concentrated to obtain about 2,620 g of a solution containing 15% by weight of polyimide (A-6) having an imidation ratio of about 95%. Got.
A small amount of this solution was collected, and γ-butyrolactone was added thereto, and the solution viscosity measured as a solution having a concentration of 6.0% by weight was 18 mPa · s.

Synthesis Example 7 (Synthesis example 2 of other polyimide)
As tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride 73 g (0.33 mol) and p-phenylenediamine 30 g (0.28 mol) as a diamine compound and the formula (D-10) A solution containing polyamic acid was obtained by dissolving 36 g (0.069 mol) of the diamine represented in 560 g of N-methyl-2-pyrrolidone and reacting at 60 ° C. for 6 hours. A small amount of the obtained polyamic acid solution was collected, and the solution viscosity measured as a 10 wt% solution by adding N-methyl-2-pyrrolidone was 80 mPa · s.
1,600 g of N-methyl-2-pyrrolidone was added to 600 g of the obtained polyamic acid solution, 26 g of pyridine and 34 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 γ-butyrolactone and further concentrated to obtain 790 g of a solution containing 10% by weight of polyimide (A-7) having an imidization ratio of about 92%. .
A small amount of this solution was collected, and γ-butyrolactone was added to measure the solution viscosity as a solution having a concentration of 6% by weight of 30 mPa · s.

Synthesis Example 8 (Synthesis Example 3 of other polyimide)
77 g (0.34 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic anhydride and 38 g (0.36 mol) of p-phenylenediamine as diamine were added to N-methyl-2-pyrrolidone 1, A solution containing polyamic acid was obtained by dissolving in 260 g and reacting at room temperature for 6 hours. A small amount of the obtained polyamic acid solution was collected and concentrated under reduced pressure, and the solution viscosity measured as a solution having a concentration weight of 10% was 90 mPa · s.
Next, 600 g of N-methyl-2-pyrrolidone was added to the obtained polyamic acid solution, 136 g of pyridine and 105 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 γ-butyrolactone and further concentrated to obtain 760 g of a solution containing 15% by weight of polyimide (A-8) having an imidation ratio of about 95%. .
A small amount of this solution was collected, and γ-butyrolactone was added thereto, and the solution viscosity measured as a solution having a concentration of 6.0% by weight was 25 mPa · s.

Synthesis Example 9 (Synthesis Example 4 of other polyimide)
224 g (1.0 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic anhydride, 87 g (0.8 mol) of p-phenylenediamine as diamine, 23 g of 4,4′-diaminodiphenylmethane ( 0.1 mol) and 32 g (0.1 mol) of 2,2′-trifluoromethyl-4,4′-diaminobiphenyl are dissolved in 2,700 g of N-methyl-2-pyrrolidone and reacted at room temperature for 6 hours. As a result, a solution containing polyamic acid was obtained. A small amount of the obtained polyamic acid solution was collected, and the solution viscosity measured as a 10 wt% solution by adding N-methyl-2-pyrrolidone was 80 mPa · s.
Next, 2,000 g of N-methyl-2-pyrrolidone was added to the obtained polyamic acid solution, 150 g of pyridine and 200 g of acetic anhydride were added, and a dehydration ring closure reaction 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 and further concentrated to obtain 2,400 g of a solution containing 15% by weight of polyimide (A-9) having an imidization ratio of about 95%. Obtained.
A small amount of this solution was collected, and γ-butyrolactone was added thereto, and the solution viscosity measured as a solution having a concentration of 6.0% by weight was 25 mPa · s.

Synthesis Example 10 (Synthesis example 5 of other polyimide)
1,3,3a, 4,5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) naphtho [1,2-c] furan-1,3-dione as tetracarboxylic anhydride 150 g (0.50 mol) and 43.2 g (0.40 mol) of p-phenylenediamine and 15.2 g (0.10 mol) of 3,5-diaminobenzoic acid as N-methyl-2-pyrrolidone 1, A solution containing polyamic acid was obtained by dissolving in 220 g and reacting at room temperature for 6 hours. A small amount of the obtained polyamic acid solution was taken, N-methyl-2-pyrrolidone was added, and the solution viscosity measured as a solution having a concentration of 10% by weight was 90 mPa · s.
Next, 600 g of N-methyl-2-pyrrolidone was added to the obtained polyamic acid solution, 136 g of pyridine and 105 g of acetic anhydride were added, and dehydration ring closure reaction 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 and further concentrated to obtain 1,380 g of a solution containing 15% by weight of polyimide (A-10) having an imidization ratio of about 91%. Obtained.
A small amount of this solution was collected, and γ-butyrolactone was added thereto, and the solution viscosity measured as a solution having a concentration of 6.0% by weight was 25 mPa · s.

Synthesis Example 11 (Synthesis Example 1 of other polyamic acid)
196 g (1.0 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride as tetracarboxylic dianhydride and 212 g (1, .2) of 2,2′-dimethyl-4,4′-diaminobiphenyl as diamine. 0 mol) is dissolved in a mixed solvent composed of 370 g of N-methyl-2-pyrrolidone and 3,300 g of γ-butyrolactone, and reacted at 40 ° C. for 3 hours to contain 10% by weight of polyamic acid (B-1). About 4,200 g of solution was obtained.
The solution viscosity of this solution was 210 mPa · s.
Synthesis Example 12 (Synthesis Example 2 of other polyamic acid)
1,2,3,4-cyclobutanetetracarboxylic dianhydride 20 g (0.1 mol) and pyromellitic anhydride 196 g (0.9 mol) as tetracarboxylic dianhydride and 4,4′- as diamine By dissolving 159 g (0.8 mol) of diaminodiphenyl ether and 21 g (0.2 mol) of p-phenylenediamine in 3,600 g of N-methyl-2-pyrrolidone and reacting at 40 ° C. for 4 hours, polyamic acid (B About 4,000 g of a solution containing 10% by weight of -2).
The solution viscosity of this solution was 400 mPa · s.

Example 1
<Preparation of liquid crystal aligning agent>
An amount corresponding to 20 parts by weight of the solution containing the polyimide (A-1) obtained in Synthesis Example 1 in terms of polyimide (A-1) and the polyamic acid (B-1) obtained in Synthesis Example 11 An amount corresponding to 80 parts by weight in terms of polyamic acid (B-1) was added to the solution containing γ-butyrolactone, N-methyl-2-pyrrolidone and butyl cellosolve, and γ-butyrolactone: N-methyl. In addition, the weight ratio of 2-pyrrolidone: butyl cellosolve is 71:17:12, and N, N, N ′, N′-tetraglycidyl-4,4 ′, which is an epoxy compound as an adhesion improver. -2 parts by weight of diaminodiphenylmethane was added to prepare a solution having a solid content of 3.5 weight. After sufficiently stirring this solution, a liquid crystal aligning agent was prepared by filtering using a filter having a pore size of 1 μm.
Evaluation was performed as follows using this liquid crystal aligning agent.

<Manufacture and evaluation of liquid crystal display elements>
[Manufacture of liquid crystal display elements]
The liquid crystal aligning agent prepared above was applied on a transparent conductive film made of an ITO film provided on one surface of a glass substrate having a thickness of 1 mm using a spinner under conditions of a rotation speed of 2,000 rpm and a rotation time of 20 seconds. By heating at 200 ° C. for 1 hour to remove the solvent, a film having a thickness of 0.08 μm was formed. A rubbing machine having a roll in which a rayon cloth is wound around this film is subjected to a rubbing process under the conditions of a roll rotation speed of 400 rpm, a stage moving speed of 3 cm / second, and a hair foot indentation length of 0.4 mm. A liquid crystal alignment film was prepared by imparting liquid crystal alignment ability to the above. The substrate having the liquid crystal alignment film was subjected to ultrasonic cleaning for 1 minute in ultrapure water and then dried in a clean oven at 100 ° C. for 10 minutes. By repeating the same operation, two substrates (a pair) having a liquid crystal alignment film were prepared.
Next, after applying an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm to each outer edge of the substrate having the liquid crystal alignment film of 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, a nematic liquid crystal (MLC-6221, manufactured by Merck & Co., Inc.) having a positive dielectric anisotropy is filled between the liquid crystal inlet and the substrate, and then the liquid crystal inlet is filled with an acrylic photo-curing adhesive. The liquid crystal display element was manufactured by sealing and bonding a polarizing plate on both surfaces of the outer side of a board | substrate.

[Evaluation of liquid crystal display elements]
(1) Evaluation of liquid crystal orientation The liquid crystal display element manufactured above was observed under a crossed nicols using a polarizing microscope. At this time, the liquid crystal orientation "good" and light leakage were observed when there was no light leakage. When the liquid crystal orientation was evaluated as “poor”, the liquid crystal orientation of this liquid crystal display element was “good”.
(2) Evaluation of heat resistance (heat stress test)
For the liquid crystal display device manufactured above, a voltage of 5 V was first applied with an application time of 60 microseconds and a span of 167 milliseconds, and then the voltage holding ratio after 167 milliseconds from the application release was measured. The value of this time was the initial voltage holding ratio _{(VHR BF).} After the VHR _BF measurement, the liquid crystal display element was put in an oven at 100 ° C., and thermal stress was applied for 1,000 hours. Next, the liquid crystal display element was allowed to stand at room temperature and cooled to room temperature, and then the voltage holding ratio VHR _AF after application of thermal stress was measured.
Using the following formula (ii), the rate of change of the voltage holding ratio before and after the application of thermal stress is obtained, and when the rate of change is less than 3%, the heat resistance is “good”, and when it is 3% or more, the heat resistance is “bad” As a result, the heat resistance of this liquid crystal display element was “good”.

  In addition, "VHR-1" manufactured by Toyo Corporation was used for measurement of the voltage holding ratio.

Example 2
<Preparation of liquid crystal aligning agent>
An amount corresponding to 100 parts by weight in terms of the polyimide (A-2) in the solution containing the polyimide (A-2) obtained in Synthesis Example 2 was taken, and γ-butyrolactone, N-methyl-2- Pyrrolidone and butyl cellosolve are added so that the ratio of γ-butyrolactone: N-methyl-2-pyrrolidone: butyl cellosolve is 40:30:20 by weight, and N, N, N which is an epoxy compound as an adhesion improver 2 parts by weight of ', N'-tetraglycidyl-4,4'-diaminodiphenylmethane was added to prepare a solution having a solid content concentration of 3.5 wt. After sufficiently stirring this solution, a liquid crystal aligning agent was prepared by filtering using a filter having a pore size of 1 μm.
<Manufacture and evaluation of liquid crystal display elements>
In Example 1, a liquid crystal display device was produced in the same manner as in Example 1 except that nematic liquid crystal (MLC-2038, manufactured by Merck & Co., Inc.) having a negative dielectric anisotropy was used as the liquid crystal. The orientation and heat resistance were evaluated. The results are shown in Table 1.

Example 3
<Preparation of liquid crystal aligning agent>
An amount corresponding to 100 parts by weight in terms of the polyimide (A-2) in the solution containing the imidized polymer (A-3) obtained in Synthesis Example 3 was taken, and an epoxy compound was used as an adhesion improver for this. 10 parts by weight of N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane and methyl 3- [2- (3-trimethoxysilylpropylamino) ethylamino which is a functional silane compound 0.75 parts by weight of propionate was added, and γ-butyrolactone and butyl cellosolve were added so that the γ-butyrolactone: butyl cellosolve ratio was 90:10 by weight to obtain a solution having a solid content concentration of 4% by weight. A liquid crystal aligning agent was prepared by filtering this solution using a filter having a pore diameter of 1 μm.
<Manufacture and evaluation of liquid crystal display elements>
In Example 1, a liquid crystal display element was manufactured in the same manner as in Example 1 except that nematic liquid crystal (MLC-2019, manufactured by Merck & Co., Inc.) having a positive dielectric anisotropy was used as the liquid crystal. The orientation and heat resistance were evaluated. The results are shown in Table 1.

Examples 4 and 5
As the polymer, liquid crystal aligning agents were prepared in the same manner as in Example 3 except that the types shown in Table 1 were used in the amounts shown in Table 1, and liquid crystal display elements were produced and evaluated. The results are shown in Table 1.
Comparative Example 1
As the polymer, a liquid crystal aligning agent was prepared in the same manner as in Example 1 except that the types shown in Table 1 were used in the amounts shown in Table 1, and liquid crystal display elements were produced and evaluated. The results are shown in Table 1.
Comparative Examples 2 and 5
As the polymer, liquid crystal aligning agents were prepared in the same manner as in Example 2 except that the types shown in Table 1 were used in the amounts shown in Table 1, and liquid crystal display elements were produced and evaluated. The results are shown in Table 1.
Comparative Examples 3 and 4
As the polymer, liquid crystal aligning agents were prepared in the same manner as in Example 3 except that the types shown in Table 1 were used in the amounts shown in Table 1, and liquid crystal display elements were produced and evaluated. The results are shown in Table 1.

In addition, the abbreviation in the “type” column of the adhesion improver in Table 1 has the following meaning.
Epoxy compound GAPM: N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane functional silane compound MSPP: methyl 3- [2- (3-trimethoxysilylpropylamino) ethylamino] propionate , “Liquid crystal name” column has the following meanings.
6221: MLC-6221 (trade name, manufactured by Merck & Co., Inc.)
2038: MLC-2038 (trade name, manufactured by Merck & Co., Inc.)
2019: MLC-2019 (trade name, manufactured by Merck & Co., Inc.)

Claims (6)

Tetracarboxylic dianhydride including 2,3,5-tricarboxycyclopentylacetic dianhydride, and the following formula (A)

Liquid crystal alignment characterized by containing at least one polymer selected from the group consisting of a polyamic acid obtained by reaction with a diamine containing a compound represented by formula (I) and a polyimide formed by dehydrating and ring-closing the polyamic acid. Agent. Diamine is further represented by the following formula (D-III)

(In the formula (D-III), R ⁷ is —O— ^* , —COO— ^* , —OCO— ^* , —NHCO— ^* , —CONH— ^* and —CO— ^* (provided with “*”). A bond is bonded to R ⁸ )), and R ⁸ has a skeleton or group selected from the group consisting of a steroid skeleton, a trifluoromethyl group, and a fluoro group It is a monovalent organic group or an alkyl group having 6 to 30 carbon atoms.)
The liquid crystal aligning agent of Claim 1 containing the compound represented by these. The formula (D-III) ^{R 7} in the -O- ^* or -COO- ^* (However, bond marked with "*" is bonded to ^{R 8.)} A and one ^{of R 8} has a steroid skeleton The liquid crystal aligning agent of Claim 2 which is a valent organic group.   The liquid crystal aligning agent as described in any one of Claims 1-3 whose diamine contains p-phenylenediamine further.   The liquid crystal aligning agent as described in any one of Claims 1-4 whose polymer contained is a polyimide.   A liquid crystal display element comprising a liquid crystal alignment film formed from the liquid crystal aligning agent according to claim 1.