JP2006010896A - Vertical liquid crystal aligning agent, and vertical alignment liquid crystal display element having reflection electrode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal aligning agent which brings about a vertical liquid crystal alignment layer excellent in image persistence characteristics and reliability even when used with a reflection electrode. <P>SOLUTION: The vertical liquid crystal aligning agent includes 100 weight parts of a polymer with an amic acid repeating unit and/or an imide repeating unit and at least 5 weight parts of a compound having at least two epoxy groups in a molecule. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vertical liquid crystal display element having a vertical liquid crystal aligning agent and a reflective electrode. More specifically, the present invention relates to a vertical liquid crystal aligning agent that provides a vertical liquid crystal alignment film having good image sticking characteristics regardless of the type of electrode constituting the liquid crystal display element, and a liquid crystal display element having a reflective electrode including the vertical liquid crystal alignment film.

  Conventionally, a cell of a sandwich structure is formed by forming a nematic liquid crystal layer having positive dielectric anisotropy between two substrates having a liquid crystal alignment film formed on the surface via a transparent conductive film, There is known a TN liquid crystal display element having a TN (Twisted Nematic) type liquid crystal cell in which the major axis of liquid crystal molecules is continuously twisted by 90 degrees from one substrate toward the other substrate.

  Further, the addition of a chiral agent achieves a state in which the major axis of the liquid crystal molecules is continuously twisted between the substrates by 180 degrees or more, and an STN (Super Twisted Nematic) type liquid crystal display element utilizing the birefringence effect generated thereby. Is also present. More recently, a homeotropically aligned nematic liquid crystal layer having negative dielectric anisotropy between opposing substrates and a cholesteric liquid crystal layer in which the helical axis is parallel to the substrate normal are formed. A guest-host type reflective liquid crystal display element in which a dye is added to the above has also been developed. The alignment of the liquid crystal in these liquid crystal display elements is usually expressed by a liquid crystal alignment film subjected to a rubbing treatment. Here, as a material for the liquid crystal alignment film constituting the liquid crystal display element, polyimide, polyamide, polyester, and the like are conventionally known. In particular, polyimide is used in many liquid crystal display elements because of its excellent heat resistance, affinity with liquid crystals, mechanical strength, and the like.

  Recently, studies on improving display quality such as higher definition of liquid crystal display elements and lowering power consumption have been made, and the range of use of liquid crystal display elements has been expanded. In particular, reflective or transflective liquid crystal display elements that can maintain high display quality when used outdoors are used in mobile terminals, so that various metal electrodes (hereinafter referred to as reflective electrodes) are used to exhibit the function of reflecting external light. Is used. However, in a vertical liquid crystal display element having a reflective electrode, when using an alignment film that has been used in a conventional ITO electrode, the reliability such as image sticking or alignment stains occurs during long-term lighting. There was a problem.

  An object of the present invention is to provide a liquid crystal aligning agent that provides a vertical liquid crystal alignment film having excellent image sticking characteristics and reliability even when used with a reflective electrode.

  Another object of the present invention is to provide a vertical liquid crystal display element having a reflective electrode comprising a vertical liquid crystal alignment film obtained from the liquid crystal aligning agent of the present invention.

  Still other objects and advantages of the present invention will become apparent from the following description.

  According to the present invention, the above objects and advantages of the present invention are as follows: 100 parts by weight of a polymer having a repeating unit represented by the following formula (A) and / or a repeating unit represented by the following formula (B): It is achieved by a liquid crystal aligning agent characterized in that it contains at least 5 parts by weight of a compound having at least two epoxy groups therein.

(Wherein P ¹ is a tetravalent organic group and Q ¹ is a divalent organic group.)

(Wherein P ² is a tetravalent organic group and Q ² is a divalent organic group.)

The vertical liquid crystal alignment film formed by the liquid crystal aligning agent of the present invention is not limited to the case where it is used with an ITO electrode, but is excellent in seizure characteristics and reliability even when used with a reflective electrode, and is suitable for constituting a liquid crystal display element. Can be used for

  The liquid crystal display element of the present invention can be effectively used in various devices, and is suitable for display devices such as desk calculators, watches, table clocks, mobile phones, counting display boards, word processors, personal computers, and liquid crystal televisions. Can be used.

  Hereinafter, the present invention will be described in detail.

  The liquid crystal aligning agent in the present invention contains a polymer having a repeating unit represented by the above formula (A) and / or a repeating unit represented by the above formula (B) (hereinafter referred to as “specific polymer”). . The specific polymer may be (1) a mixture of a polyamic acid having a repeating unit represented by the above formula (I) and a polyimide having a repeating unit represented by the above formula (B), (2) A polymer in which the repeating unit represented by the above formula (I) and the repeating unit represented by the above formula (B) are bonded in the same molecule in a random or block form (hereinafter referred to as “partially imidized polymer”). May also be referred to).

  The polyamic acid is obtained by ring-opening polyaddition of a tetracarboxylic dianhydride and a diamine compound. Polyimide is usually obtained by dehydrating and ring-closing polyamic acid. The partially imidized polymer can be usually obtained by a method of partially dehydrating and ring-closing polyamic acid or a method of synthesizing a block copolymer by combining an amic acid prepolymer and an imide prepolymer.

<Polyamic acid>
[Tetracarboxylic dianhydride]
Examples of tetracarboxylic dianhydride include butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutane. Tetracarboxylic 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-tricarboxycyclopentylacetic acid dianhydride, 3,5,6- Recarboxynorbornane-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) -naphth [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-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 (I ) And aliphatic and alicyclic tetracarboxylic dianhydrides such as compounds represented by (II);

(Wherein R ¹ and R ³ represent a divalent organic group having an aromatic ring, R ² and R ⁴ represent a hydrogen atom or an alkyl group, and a plurality of R ² and R ⁴ are the same. But it may be different.)

  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′-bi (3,4-Dicarboxyphenoxy) diphenylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidenediphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid Dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenyl) Phthalic acid) -4,4'-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4'-diphenylmethane dianhydride, ethylene glycol-bis (anhydrotrimellitate), propylene glycol-bis (an Hydrotrimellitate), 1,4-butanediol-bis (anhydrotrimellitate), 1,6-hexa Diol-bis (anhydro trimellitate), 1,8-octanediol-bis (anhydro trimellitate), 2,2-bis (4-hydroxyphenyl) propane-bis (anhydro trimellitate), below Aromatic tetracarboxylic dianhydrides such as compounds represented by formulas (1) to (4) can be given. These may be used alone or in combination of two or more.

  Of these, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 5- ( 2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic 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 − Oxo-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 Acid dianhydride, 3-oxabicyclo [3.2.1] octane-2,4-dione-6-spiro-3 ′-(tetrahydrofuran-2 ′, 5′-dione), pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride Of the anhydrides, compounds represented by the above formula (I) Among the compounds represented by the formulas (5) to (7) and the compound represented by the above formula (II), the compound represented by the following formula (8) can exhibit good liquid crystal alignment. It is preferable from the viewpoint. Particularly preferred are 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5 Cyclohexanetetracarboxylic dianhydride, 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'-Geo ), It may be mentioned compounds represented by pyromellitic dianhydride and the following formula (5).

In particular, when both the repeating unit (amic acid unit) represented by the above formula (a) and the repeating unit (imide unit) represented by the above formula (b) are present, it is represented by P ¹ in (a). and tetravalent organic group, tetravalent organic group represented by P ² in the repeating unit (imide units) represented by the (b), but each may be the same or different and the P ¹ Preferable examples include groups represented by the following formulas (i) and (i ′). P ² is preferably a group having an alicyclic skeleton, particularly preferably a group represented by each of the following formulas (ii) and (ii ′).

Wherein R is a halogen atom, a methyl group or an ethyl group, a is an integer of 0 or 1, b is an integer of 0 to 5, and c and d are each independently an integer of 0 to 4. is there.)

  Specific examples of preferable tetracarboxylic dianhydrides in each repeating unit include tetracarboxylic dianhydrides constituting the amic acid unit, such as 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1 , 3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, pyromellitic dianhydride and the like. The tetracarboxylic dianhydride constituting the imide unit is preferably an alicyclic tetracarboxylic dianhydride, particularly 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, 3-oxabicyclo [3.2.1 And octane-2,4-dione-6-spiro-3 ′-(tetrahydrofuran-2 ′, 5′-dione).

[Diamine compound]
Examples of the diamine compound 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′-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, , 4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexa Fluoropropane, 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′-tetra Loro-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] -octafluorobiphenyl, 4 -Aromatic diamines such as (4-n-heptylcyclohexyl) phenoxy-2,4-diaminobenzene;

1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1 , 4-diaminocyclohexane, isophorone diamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylene methylene diamine, tricyclo [6.2.1.0 ^2,7 ] -undecylenedimethyl diamine, 4 Aliphatic and cycloaliphatic diamines such as 4,4'-methylenebis (cyclohexylamine);
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 2 in the molecule such as phenylphenanthridine, 1,4-diaminopiperazine, 3,6-diaminoacridine, bis (4-aminophenyl) phenylamine and compounds represented by the following formulas (III) to (IV) A diamine having one primary amino group and a nitrogen atom other than the primary amino group;

(In the formula, R ⁵ represents a monovalent organic group having a ring structure containing a nitrogen atom selected from pyridine, pyrimidine, triazine, piperidine and piperazine, and X represents a divalent organic group.)

Wherein X represents a divalent organic group having a ring structure containing a nitrogen atom selected from pyridine, pyrimidine, triazine, piperidine and piperazine, R ⁶ represents a divalent organic group, and a plurality of X May be the same or different.)
Mono-substituted phenylenediamines represented by the following formula (V); diaminoorganosiloxanes represented by the following formula (VI);

(Wherein R ⁷ represents a divalent organic group selected from —O—, —COO—, —OCO—, —NHCO—, —CONH— and —CO—, and R ⁸ represents a steroid skeleton, A monovalent organic group having a group selected from a fluoromethyl group and a fluoro group or an alkyl group having 6 to 30 carbon atoms is shown.)

(Wherein R ⁹ represents a hydrocarbon group having 1 to 12 carbon atoms, and a plurality of R ⁹ may be the same or different, p is an integer of 1 to 3, and q is 1 to 20) Is an integer.)
Examples include compounds represented by the following formulas (9) to (13). These diamine compounds can be used alone or in combination of two or more.

(In the formula, y is an integer of 2 to 12, and z is an integer of 1 to 5.)

  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 Aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, 4- (4-n-heptylcyclohexyl) phenoxy-2,4-diaminobenzene, represented by the above formulas (9) to (13) Of the compounds represented by formula (III), 2,6-diaminopyridine, 3,4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, and the compound represented by the above formula (III) Of the compounds represented by the formula (IV), the compounds represented by the following formula (15) and the compounds represented by the formula (V) are represented by the following formulas (16) to (21). Are preferred.

[Synthetic reaction of polyamic acid]
The ratio of the tetracarboxylic dianhydride and the diamine compound used for the polyamic acid synthesis reaction is such that the acid anhydride group of the tetracarboxylic dianhydride is 0.1 relative to 1 equivalent of the amino group contained in the diamine compound. A ratio of 2 to 2 equivalents is preferable, and a ratio of 0.3 to 1.2 equivalents is more preferable.

  The synthetic reaction of polyamic acid is preferably carried out in an organic solvent under a temperature condition of -20 to 150 ° C, more preferably 0 to 100 ° C. Here, the organic solvent is not particularly limited as long as it can dissolve the synthesized polyamic acid. For example, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide And aprotic polar solvents such as 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

[Poor solvent]
Alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc., which are poor solvents for polyamic acid, may be used in combination with the organic solvent as long as the resulting polyamic acid does not precipitate. it can. 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 and the like.

  As described above, a reaction solution obtained by dissolving polyamic acid is obtained. The reaction solution is poured into a large amount of poor solvent to obtain a precipitate, and the precipitate is dried under reduced pressure to obtain a polyamic acid. The polyamic acid can be purified by dissolving the polyamic acid again in an organic solvent and then precipitating with a poor solvent once or several times.

[Imidized polymer]
<Imidized polymer>
The imidized polymer constituting the liquid crystal aligning agent of the present invention can be prepared by dehydrating and ring-closing the polyamic acid. The dehydration and ring closure of the polyamic acid can be performed, for example, by (i) a method of heating the polyamic acid or (ii) dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration ring closure catalyst to this solution, and heating as necessary. This method is advantageously performed.

  The reaction temperature in the method of heating the polyamic acid (i) is preferably 50 to 200 ° C, more preferably 60 to 170 ° C. If the reaction temperature is less than 50 ° C., the dehydration ring-closure reaction does not proceed sufficiently, and if the reaction temperature exceeds 200 ° C., the molecular weight of the imidized polymer obtained 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. The amount of the dehydrating agent used is preferably 0.01 to 20 mol relative to 1 mol of the polyamic acid repeating unit. 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 same organic solvent as 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. In addition, the imidized polymer can be purified by performing the same operation as the polyamic acid purification method on the reaction solution thus obtained.

[Partial imide]
<Partially imidized polymer>
The partially imidized polymer used in the present invention has a structure obtained by partially imidizing the polyamic acid. The imidation ratio in the partially imidized polymer used in the present invention is preferably 10 to 90%, more preferably 30 to 70%. Here, the “imidation ratio” is the percentage of the number of repeating units that form an imide ring with respect to the total number of repeating units in the polymer. At this time, a part of the imide ring may be an isoimide ring.

  As a method for synthesizing a partially imidized polymer, for example, (i) a method of synthesizing by partially dehydrating and cyclizing the polyamic acid by heating, and (ii) dissolving the polyamic acid in an organic solvent, this solution A method in which a dehydrating agent and a dehydrating ring-closing catalyst are added and heated as necessary to partially dehydrate and cyclize, or (iii) tetracarboxylic dianhydride, diamine compound and diisocyanate compound are mixed And the method of condensing and synthesizing by heating as needed is used.

  In the method (i), the reaction temperature is preferably 300 ° C. or less, more preferably 100 to 250 ° C. When the reaction temperature exceeds 300 ° C., the molecular weight of the resulting imide group-containing polyamic acid may decrease.

  On the other hand, examples of the dehydrating agent used in the method (ii) include acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride. The amount of the dehydrating agent used is preferably 0.2 to 20 mol with respect to 1 mol of the polyamic acid repeating unit. Moreover, as a dehydration ring closure catalyst, tertiary amines, such as a pyridine, a collidine, a lutidine, a triethylamine, can be used, for example. It is not limited to these. Moreover, it is preferable that the usage-amount of an imidation catalyst shall be 0.1-10 mol with respect to 1 mol of dehydrating agents to be used. In addition, as an organic solvent used for reaction of dehydration ring closure, the same organic solvent as 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 becomes like this. Preferably it is 0-180 degreeC, More preferably, it is 60-150 degreeC. Further, the partially imidized polymer can be purified by performing the same operation as the polyamic acid purification method on the reaction solution thus obtained.

  Specific examples of the diisocyanate compound used in the reaction (iii) include aliphatic diisocyanates such as hexamethylene diisocyanate; cyclohexane-1,2-diisocyanate, 1-methylcyclohexane-2,4-diisocyanate, 1,2-dimethyl. Cyclohexane-ω, ω′-diisocyanate, 1,4-dimethylcyclohexane-ω, ω′-diisocyanate, isophorone diisocyanate, 1,3,5-trimethyl-2-propylcyclohexane-1ω, 2ω-diisocyanate, dicyclohexylmethane-4, Cycloaliphatic diisocyanates such as 4′-diisocyanate; diphenylmethane-4,4′-diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, 1-methyl And aromatic diisocyanates such as bets - 2,4-phenylene diisocyanate, 1-methyl-2,6-phenylene diisocyanate, diisocyanates represented by the following formula (22) to (26).

  Of these, preferred are dicyclohexylmethane-4,4′-diisocyanate, diphenylmethane-4,4′-diisocyanate, 1-methyl-2,4-phenylene diisocyanate, and 1-methyl-2,6-phenylene diisocyanate. . These can be used alone or in combination of two or more. In addition, a catalyst is not particularly required for the reaction (iii), and the reaction temperature is preferably 50 to 200 ° C, more preferably 100 to 160 ° C.

[Terminal modification]
<End-modified polymer>
The polyamic acid and the partially imidized polymer may be of a terminal modified type with a controlled molecular weight. By using this terminal-modified polymer, the coating characteristics of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. Such a terminal-modified type can be synthesized by adding an acid monoanhydride, a monoamine compound, a monoisocyanate compound or the like to the reaction system when synthesizing the polyamic acid. Here, 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 and the like. Examples of monoamine compounds include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, and n-undecylamine. N-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n-eicosylamine, etc. Can do. Examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

[Logarithmic viscosity]
<Logarithmic viscosity of polymer>
The logarithmic viscosity (η _ln ) of the polyamic acid and the partially imidized polymer obtained as described above is preferably 0.05 to 10 dl / g, more preferably 0.05 to 5 dl / g.

The value of the logarithmic viscosity (η _ln ) in the present invention is determined by measuring the viscosity at 30 ° C. for a solution having a concentration of 0.5 g / 100 ml using N-methyl-2-pyrrolidone as a solvent. ).

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention is constituted by dissolving a specific polymer in an organic solvent.

  As an organic solvent which comprises the liquid crystal aligning agent of this invention, the same solvent as the solvent illustrated as what is used for the synthesis reaction of a polyamic acid can be mentioned. Moreover, the same solvent as the poor solvent illustrated as what can be used together in the synthesis reaction of a polyamic acid can also be selected suitably, and can be used together.

  The solid content concentration in the liquid crystal aligning agent of the present invention is selected in consideration of viscosity, volatility, etc., but is preferably in the range of 1 to 10% by weight. That is, the liquid crystal aligning agent of the present invention is applied to the substrate surface to form a coating film that becomes a liquid crystal alignment film. When the solid content concentration is less than 1% by weight, the coating film thickness is It is too small to obtain a good liquid crystal alignment film. When the solid content concentration exceeds 10% 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 is increased, so that the coating properties tend to be inferior. Moreover, 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.

  The liquid crystal aligning agent of the present invention contains at least 5 parts by weight of a compound having at least two epoxy groups in the molecule (hereinafter also referred to as “epoxy group-containing compound”) with respect to 100 parts by weight of the specific polymer. To do.

  Examples of the epoxy group-containing 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, 1,6 -Hexanediol 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 , And the like as preferred 4'-diaminodiphenylmethane. The content of the epoxy compound is preferably 5 to 40 parts by weight, more preferably 10 to 30 parts by weight with respect to 100 parts by weight of the specific polymer contained in the aligning agent, and the characteristics as the aligning agent are impaired. It can be contained to the extent that it is not.

  Moreover, the liquid crystal aligning agent of this invention may contain the functional silane containing compound (henceforth "silane coupling agent"). Examples of the silane coupling agent 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- Examples thereof include bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, and 3-glycidoxypropyltrimethoxysilane.

  The blending ratio of these silane coupling agents 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 specific polymer.

<Liquid crystal display element>
The liquid crystal display element obtained using the liquid crystal aligning agent of this invention can be manufactured, for example with the following method.
(1) The liquid crystal aligning agent of the present invention is applied to one surface of a substrate on which a patterned transparent conductive film is provided by a method such as a roll coater method, a spinner method, a printing method, an ink jet method, etc. 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, or polycarbonate can be used. As the 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. Can be used. For patterning these transparent conductive films, a photo-etching method or a method using a mask in advance is used. A metal such as Al or Ag or an alloy containing these metals can be used for the reflective electrode. As long as it has sufficient reflectivity, it is not limited to these. When applying the liquid crystal aligning agent, a functional silane-containing compound, a functional titanium-containing compound, or the like is provided on the surface of the substrate in order to further improve the adhesion between the substrate surface and the transparent conductive film or reflective electrode and the coating film. Can also be applied in advance. The heating temperature after application of the liquid crystal aligning agent is preferably 80 to 300 ° C, more preferably 120 to 250 ° C. The liquid crystal aligning agent of the present invention containing a polyamic acid forms a coating film that becomes an alignment film by removing the organic solvent after coating. It can also be a membrane. The film thickness of the formed coating film is preferably 0.001-1 μm, more preferably 0.005-0.5 μm.
(2) As shown in Japanese Patent Application Laid-Open No. 2002-327058, a structure is formed on a substrate using a photosensitive resin, and a vertical liquid crystal alignment film is formed thereon. To do.
(3) Two substrates on which the vertical liquid crystal alignment film is formed as described above are manufactured, the two substrates are arranged to face each other with a gap (cell gap) therebetween, and the peripheral portions of the two substrates are sealed. A liquid crystal cell is formed by laminating using an agent, injecting and filling liquid crystal into the cell gap defined by the substrate surface and the sealing agent, and sealing the injection hole. And a liquid crystal display element is obtained by arrange | positioning a polarizing plate to the outer surface of a liquid crystal cell, ie, the transparent substrate side which comprises 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.

  Examples of the liquid crystal include nematic liquid crystal and smectic liquid crystal. Among them, nematic liquid crystal is preferable, for example, Schiff base liquid crystal, azoxy liquid crystal, biphenyl liquid crystal, phenyl cyclohexane liquid crystal, ester liquid crystal, terphenyl liquid crystal, biphenyl cyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, bicyclooctane. Type liquid crystal, cubane type liquid crystal and the like can be used. Further, for these liquid crystals, for example, cholesteric liquid crystals such as cholestyl chloride, cholesteryl nonate, cholesteryl carbonate, and chiral agents such as those sold under the trade names “C-15” and “CB-15” (manufactured by Merck). Etc. can also be used. Furthermore, a ferroelectric liquid crystal such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate can also be used.

  Further, as a polarizing plate to be 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 sandwiching and stretching polyvinyl alcohol is sandwiched between cellulose acetate protective films. 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. Transparency, voltage holding ratio, and image sticking in Examples and Comparative Examples were evaluated by the following methods.

[transparency]
A HITACHI U-2010 spectrophotometer (manufactured by Hitachi, Ltd.) was used as the measuring apparatus. A liquid crystal aligning agent of the present invention prepared as described above was applied onto a quartz substrate having a thickness of 1.5 mm using a spinner and dried at 180 ° C. for 1 hour to form a coating film having a dry film thickness of 800 mm. Formed. The transmittance of the prepared coating film was measured. In the transmittance measurement, values at wavelengths of 700 nm, 600 nm, 500 nm, 450 nm, 400 nm, 350 nm, and 300 nm were obtained. The case where the transmittance was 90% or higher at any measurement wavelength was judged as good, and the other cases were judged as bad.

[Vertical alignment]
The liquid crystal display element at the time of voltage OFF and AC 12V (peak-peak) was observed under crossed Nicols.

[Burn in]
A 30 Hz, 2.0 V rectangular wave with 1.0 V DC superimposed on the liquid crystal display element is applied at an environmental temperature of 50 ° C. for 1 hour, and the voltage remaining in the liquid crystal cell immediately after the DC voltage is turned off is flicker-erased. Was obtained as a residual DC voltage. The value of the residual DC is 2V or less regardless of the electrode type constituting the liquid crystal display element, and the case where the difference of the residual DC between each electrode type is 0.5V or less is good, and the case other than that is bad. .

[Reliability test of liquid crystal display elements (presence of display defects)]
In a high-temperature and high-humidity environment (temperature 70 ° C., relative humidity 80%), the liquid crystal display element was driven with a rectangular wave of 5 V and 60 Hz, and the presence or absence of display defects after 100 hours was observed with a polarizing microscope.

Synthesis example 1
2,3,4-tricarboxycyclopentylacetic acid dianhydride 224.17 g (1.0 mol) as tetracarboxylic dianhydride, p-phenylenediamine 54.07 g (0.5 mol) as the diamine compound, 161.41 g (0.5 mol) of the diamine compound represented by 16) was dissolved in 4,500 g of N-methyl-2-pyrrolidone and reacted at 60 ° C. for 6 hours. The reaction solution was then poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 520 g of polyamic acid having a logarithmic viscosity of 0.57 dl / g (referred to as “polyamic acid (A-1)”).

Synthesis example 2
In Synthesis Example 1, Synthesis Example 1 except that 94.62 g (0.8 mol) of p-phenylenediamine and 104.56 g (0.2 mol) of the diamine compound represented by the above formula (16) were used as the diamine compound. In the same manner as above, 390 g of polyamic acid having a logarithmic viscosity of 0.46 dl / g was obtained. 30 g of the resulting polyamic acid was dissolved in 570 g of N-methyl-2-pyrrolidone, 5.7 g of pyridine and 7.4 g of acetic anhydride were added, and dehydration was carried out at 110 ° C. for 4 hours, followed by precipitation, washing, The pressure was reduced to obtain 19.5 g of polyimide having a logarithmic viscosity of 0.53 dl / g (referred to as “polyimide (A-2)”).

Synthesis example 3
In Synthesis Example 2, Synthesis Example 2 except that p-phenylenediamine 64.88 g (0.6 mol) and diamine compound 209.13 g (0.4 mol) represented by the above formula (16) were used as the diamine compound. In the same manner as above, 450 g of polyamic acid having a logarithmic viscosity of 0.33 dl / g was obtained. Thereafter, a polyimide having a logarithmic viscosity of 0.41 dl / g (referred to as “polyimide (A-3)”) in the same manner as in Synthesis Example 2 except that 4.8 g of pyridine and 6.1 g of acetic anhydride were used. 1 g was obtained.

Synthesis example 4
In Synthesis Example 2, as a diamine compound, 75.70 g (0.7 mol) of p-phenylenediamine, 39.65 g (0.2 mol) of 1,1-bis (4-aminophenyl) methane, and the above formula (16) Except for using 52.28 g (0.1 mol) of the diamine compound represented, 363 g of polyamic acid having a logarithmic viscosity of 0.39 dl / g was obtained in the same manner as in Synthesis Example 2. Thereafter, a polyimide having a logarithmic viscosity of 0.50 dl / g (referred to as “polyimide (A-4)”) is obtained in the same manner as in Synthesis Example 2 except that 12.1 g of pyridine and 15.6 g of acetic anhydride are used. 3 g was obtained.

Synthesis example 5
In Synthetic Example 4, logarithmic viscosity of 0.8 was obtained in the same manner as in Synthetic Example 4 except that 37.66 g (0.1 mol) of 2,4-diamino-1-octadecyloxybenzene was used instead of diamine compound (16). 24.3 g of 42 dl / g of polyimide (this is referred to as “polyimide (A-5)”) was obtained.

Synthesis Example 6
In Synthesis Example 4, the same procedure as in Synthesis Example 4 except that 36.65 g (0.1 mol) of 4- (4-n-heptylcyclohexyl) phenoxy-2,4-diaminobenzene was used instead of the diamine compound (16). Thus, 24.0 g of polyimide having a logarithmic viscosity of 0.49 dl / g (referred to as “polyimide (A-6)”) was obtained.

Synthesis example 7
In Synthesis Example 1, the tetracarboxylic dianhydride was pyromellitic anhydride 109.06 g (0.5 mol) and cyclobutanetetracarboxylic dianhydride 98.06 g (0.5 mol). A polyamic acid having a logarithmic viscosity of 0.95 dl / g (this is referred to as “polyamic acid (B-1)”, except that 198.27 g (1.0 mol) of 4′-diaminodiphenylmethane was used. ) 401 g was obtained.

Synthesis example 8
In Synthesis Example 7, a polyamic acid (having a logarithmic viscosity of 0.81 dl / g) was prepared in the same manner as in Synthesis Example 7 except that 200.5 g (1.01 mol) of 4,4′-diaminodiphenylmethane was used as the diamine compound. 410 g of polyamic acid (B-2) ”was obtained.

Synthesis Example 9
In Synthesis Example 2, an imide prepolymer was synthesized in the same manner as in Synthesis Example 2 except that 85.43 g (0.79 mol) of p-phenylenediamine was used, and dissolved in N-methyl-2-pyrrolidone to obtain a solid content. A solution having a concentration of 10% by weight was obtained. Further, the polyamic acid (B-2) obtained in Synthesis Example 8 was used as an amic acid prepolymer, and similarly dissolved in N-methyl-2-pyrrolidone to obtain a solution having a solid content concentration of 10% by weight. Next, 500 g of the imide prepolymer solution and 500 g of the amic acid prepolymer were mixed and stirred for 2 hours, and then the reaction solution was poured into a large excess of methyl alcohol to precipitate the reaction product. Thereafter, it was washed with methyl alcohol and dried at 40 ° C. under reduced pressure for 15 hours to obtain 99 g of a partially imidized polymer having a logarithmic viscosity of 0.67 dl / g (referred to as “polymer (C-1)”). Obtained.

Synthesis Example 10
In Synthesis Example 3, an imide prepolymer was synthesized in the same manner as in Synthesis Example 3 except that p-phenylenediamine was changed to 63.80 g (0.59 mol), and thereafter, logarithmic viscosity was 0 as in Synthesis Example 9. 98 g of partially imidized polymer (referred to as “polymer (C-2)”) of .55 dl / g was obtained.

Synthesis Example 11
In Synthesis Example 4, an imide prepolymer was synthesized in the same manner as in Synthesis Example 4 except that 74.62 g (0.69 mol) of p-phenylenediamine was used. Thereafter, the logarithmic viscosity was 0 in the same manner as in Synthesis Example 9. 99 g of a partially imidized polymer (referred to as “polymer (C-3)”) of 0.72 dl / g was obtained.

Example 1
The polyamic acid (A-1) obtained in Synthesis Example 1 is dissolved in a mixed solvent of N-methyl-2-pyrrolidone / γ-butyrolactone (weight ratio 30/70) to obtain polyethylene glycol diglycidyl ether (molecular weight of about 400 ) Is dissolved in 10 parts by weight with respect to 100 parts by weight of the polymer to obtain a solution having a solid content concentration of 4% by weight. After sufficient stirring, the solution is filtered using a filter having a pore size of 1 μm to obtain the liquid crystal aligning agent of the present invention. Prepared. The liquid crystal aligning agent is 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 and a reflective film made of Al using a spinner and dried at 200 ° C. for 1 hour. As a result, a film having a dry film thickness of 0.08 μm was formed. Next, an epoxy containing aluminum oxide spheres having a diameter of 5.5 μm is disposed on the outer edges of the pair of transparent electrodes / transparent electrode substrates and the liquid crystal alignment films of the pair of transparent electrodes / reflection electrode substrates. After applying the resin adhesive, the liquid crystal alignment film surfaces were overlapped and pressed so as to face each other, and the adhesive was cured. Next, a negative type liquid crystal (MLC-6608, manufactured by Merck & Co., Inc.) is filled between the substrates through the liquid crystal injection port, and then the liquid crystal injection port is sealed with an acrylic photocuring adhesive, and polarizing plates are formed on both sides of the substrate. Were laminated to prepare a liquid crystal display element. The obtained liquid crystal display element was evaluated for image sticking and reliability. The liquid crystal aligning agent of the present invention prepared as described above was applied on a quartz substrate having a thickness of 1.5 mm using a spinner, and a coating film was formed in the same manner as in the production of a liquid crystal display element. Transparency was evaluated from the transmittance measurement of the prepared coating film. The results are shown in Table 2. It was confirmed that the liquid crystal aligning agent obtained in the present invention has good image sticking and reliability.

Examples 2-30
According to the formulations shown in Tables 1 and 2 below, polyimides (A-2) to (A-6), polyamic acids (B-1) to (B-2) obtained in Synthesis Examples 2 to 7, partial imidization weights The compounds (C-1) to (C-3), the epoxy group-containing compound and the silane coupling agent were dissolved in a mixed solvent containing γ-butyrolactone as a main component to obtain a solution having a solid content concentration of 4.0%. The liquid crystal aligning agent of the present invention was prepared by filtering the solution through a filter having a pore size of 1 μm. Using each of the liquid crystal aligning agents thus adjusted, a film was formed on the substrate surface in the same manner as in Example 1, and a liquid crystal display element was produced using the substrate on which the liquid crystal aligning film was formed. . Then, transparency, image sticking characteristics and reliability were evaluated. The results are shown in Table 2.

Comparative Examples 1-5
In accordance with the formulations shown in Tables 1 and 2 below, crystal display elements were produced in the same manner as in the examples. Then, transparency, voltage holding ratio and image sticking characteristics were evaluated. The results are shown in Table 2.

Claims (4)

100 parts by weight of a polymer having a repeating unit represented by the following formula (I) and / or a repeating unit represented by the following formula (B), and at least 5 parts by weight of a compound having at least two epoxy groups in the molecule A vertical liquid crystal aligning agent comprising:

(Wherein P ¹ is a tetravalent organic group and Q ¹ is a divalent organic group.)

(Wherein P ² is a tetravalent organic group and Q ² is a divalent organic group.) The compound having at least two epoxy groups in the molecule is at least one epoxy-containing compound selected from the group consisting of a compound represented by the following formula (c) and a compound represented by the following formula (d): 2. The vertical liquid crystal aligning agent according to 1.

(In the formula, R ⁰¹ represents a divalent aliphatic group.)

(In the formula, R ⁰² represents a divalent organic group.) The vertical liquid crystal aligning agent according to claim 1, wherein the polymer has a transmittance of 90% or more in a wavelength region of 300 nm to 700 nm. A vertical liquid crystal display element having a reflective electrode, comprising a liquid crystal alignment film formed from the vertical liquid crystal alignment agent according to claim 1.