JP2008046615A - Liquid crystal aligning agent, liquid crystal aligning film and liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal aligning agent giving a liquid crystal aligning film having a high voltage retention and good burn-in property. <P>SOLUTION: The liquid crystal aligning agent has amic acid repeating units including 2,7-diaminofluorene as a diamine component, wherein the amic acid repeating units occupy 50-90 wt.% of the sum of the amic acid repeating units and imide repeating units. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

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

Up to now, studies have been made on improving display quality, such as higher definition of liquid crystal display elements, and lowering power consumption. As a result, remarkable progress has been made as a high-performance display element. Liquid crystal display elements having a high retention rate and high reliability have been developed. However, in recent years, in addition to the conventional transmission type, the range of use of liquid crystal display elements such as a reflection type and a semi-transmission type has been expanded. As a result, the required performance for liquid crystal alignment films has become increasingly severe. In particular, demands for image sticking characteristics have become severe in a low-voltage drive type liquid crystal display element aiming at low power consumption, and it cannot be said that the performance of a conventional liquid crystal display element is sufficient. Among liquid crystal alignment films composed of polyamic acid, which is a precursor of conventional polyimide, and imide-based polymers having a structure obtained by dehydrating and cyclizing it, a liquid crystal display element is formed using the liquid crystal alignment film. When prepared, there were many having problems in image sticking characteristics even if the liquid crystal alignment ability was excellent and a sufficient voltage holding ratio was obtained.
Japanese Patent Laid-Open No. 2001-228481

  An object of the present invention is to provide a liquid crystal alignment film composed of polyamic acid and / or polyimide, which is a precursor of polyimide, which is useful as a liquid crystal alignment film, and exhibiting a high voltage holding ratio but having good image sticking characteristics. It is in providing the liquid crystal aligning agent to give.

  Another object of the present invention is to provide a liquid crystal alignment film obtained from the liquid crystal aligning agent and having excellent performance as described above.

  Still another object of the present invention is to provide a liquid crystal display device comprising the liquid crystal alignment film of the present invention.

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

The above objects and advantages of the present invention are, according to the present invention, firstly,
A polymer having an amic acid repeating unit represented by the following formula (A) and an imide repeating unit represented by the following formula (B), the amic acid repeating unit represented by the formula (A) and the formula (B) The ratio of the amic acid repeating unit represented by the formula (A) to the total of imide repeating units represented by: 50 to 90% by weight,
At least 1 part of the amic acid repeating unit represented by Formula (A) is represented by following formula (A-1), The liquid crystal aligning agent characterized by the above-mentioned.

In the formula, P ¹ is a tetravalent organic group and Q ¹ is a divalent organic group.

In the formula, P ² is a tetravalent organic group and Q ² is a divalent organic group.

In the formula, P ⁰ is a tetravalent aromatic group, and R ⁰¹ and R ⁰² are each independently a hydrogen atom or a monovalent organic group.
Achieved by:

  According to the present invention, the above objects and advantages of the present invention are secondly achieved by a liquid crystal alignment film formed from the liquid crystal aligning agent of the present invention.

  According to the present invention, thirdly, the above objects and advantages of the present invention are achieved by a liquid crystal display device comprising the liquid crystal alignment film of the present invention.

The liquid crystal alignment film formed by the liquid crystal aligning agent of the present invention has excellent image sticking characteristics as compared with conventional alignment films, and includes a TN liquid crystal display element, an STN liquid crystal display element, a reflective liquid crystal display element, and a transflective liquid crystal display element. For example, it can be suitably used for constituting various liquid crystal display elements.
The liquid crystal display element of the present invention can be effectively used in various devices, and is suitably used as a display device for, for example, a desk calculator, a wristwatch, a table clock, a mobile phone, a counting display board, a word processor, a personal computer, and a liquid crystal television. Can be used.

  Hereinafter, the present invention will be described in detail.

The liquid crystal aligning agent in this invention contains the polymer which has an amic acid repeating unit represented by the said Formula (A), and an imide repeating unit represented by the said Formula (B). The polymer may be a polymer mixture of a polyamic acid composed of an amic acid repeating unit represented by the above formula (A) and a polyimide composed of an imide repeating unit represented by the above formula (B). It may be a copolymer having an amic acid repeating unit represented by the formula (A) and an imide repeating unit represented by the above formula (B) (hereinafter sometimes referred to as “partially imidized polymer”).
The polyamic acid is obtained by ring-opening polyaddition of a tetracarboxylic dianhydride and a diamine compound, and the polyimide is usually obtained by dehydrating and ring-closing the polyamic acid. The above copolymer can be usually obtained by a method of synthesizing a block copolymer by bonding an amic acid prepolymer and an imide prepolymer.

<Polyamic acid and polyimide>
[Tetracarboxylic dianhydride]
The tetravalent organic group represented by P ¹ in the repeating unit (amic acid unit) represented by the above formula (A) and the repeating unit (imide unit) P ² represented by the above formula (B) These tetravalent organic groups are all groups derived from tetracarboxylic dianhydride. In these, the tetravalent organic groups of P ¹ and P ² are preferably not the same but different. In other words, a tetravalent organic group (P ¹ ) derived from a tetracarboxylic dianhydride constituting an amic acid bond unit and a tetravalent organic group derived from a tetracarboxylic dianhydride constituting an imide bond unit. It is preferably different from (P ² ). P ¹ in the above formula (A) preferably contains an organic group derived from pyromellitic dianhydride represented by the following formula (i).

Examples of the tetracarboxylic dianhydride constituting the amic acid unit or imide unit other than the formula (i) include 1,2,3,4-cyclobutanetetracarboxylic dianhydride and 2,3,5-tricarboxycyclopentyl. Acetic dianhydride and 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3- Dione, 2,3,6,7-naphthalenetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1, 3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dichloro-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4- Tetra Til-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride 3,3 ′, 4,4′-dicyclohexyltetracarboxylic dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride 1,3,3a, 4,5,9b-hexahydro-5-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3- Dione, 1,3,3a, 4,5,9b-hexahydro-5-ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3- Dione, 1, 3, 3a , 4,5,9b-Hexahydro-7-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a , 4,5,9b-Hexahydro-7-ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a , 4,5,9b-Hexahydro-8-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a , 4,5,9b-Hexahydro-8-ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a , 4,5,9b-Hexahydro-5,8-dimethyl-5 (tetra Dro-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), 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3 -Cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxynorbornane-2: 3,5: 6-dianhydride, 4,9-dioxatricyclo "5.3 .1.0 ^2,6 "undecane-3,5,8,10-te An aliphatic and alicyclic tetracarboxylic dianhydride such as a compound represented by the following formula (I) and (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.)
3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride Anhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl ether tetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenyl Silane 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-dicarboxyphenoxy) diphenylsulfone dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) ) Gife Nylpropane dianhydride, 3,3 ′, 4,4′-perfluoroisopropylidenediphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3 , 3′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) Dianhydride, bis (triphenylphthalic acid) -4,4'-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4'-diphenylmethane dianhydride, ethylene glycol-bis (anhydro trimellitate) ), Propylene glycol-bis (anhydro trimellitate), 1,4-butanediol-bis (anhydro trimellitate), 1,6-he Sundiol-bis (anhydro trimellitate), 1,8-octanediol-bis (anhydro trimellitate), 2,2-bis (4-hydroxyphenyl) propane-bis (anhydro trimellitate), Aromatic tetracarboxylic dianhydrides such as compounds represented by the following formulas (1) to (4) can be mentioned. 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, 5- (2,5-dioxotetrahydrofural) -3-methyl- 3-cyclohexene-1,2-dicarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic 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 − 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), 5- (2,5- Dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 3,5,6-tricarboxy-2-carboxynorbornane-2: 3,5: 6-dianhydride , 4,9-dioxatricyclo "5.3.1.0 ^2,6 Undecane-3,5,8,10-tetraone, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone Tetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, represented by the above formula (I) Among the compounds, the compound represented by each of the following formulas (5) to (7) and the compound represented by the following formula (8) among the compounds represented by the above formula (II) have good liquid crystal orientation. It is preferable because it can be expressed.

[Diamine compound]
In the repeating unit (amic acid unit) represented by the above formula (A), the divalent organic group represented by Q ¹ and the repeating unit (imide unit) Q ² represented by the above formula (B) are represented. These divalent organic groups are all derived from a diamine compound. In these, the divalent organic groups of Q ¹ and Q ² are preferably not the same but different. In other words, the divalent organic group (Q ¹ ) derived from the diamine compound constituting the amic acid bond unit and the divalent organic group (Q ² ) derived from the diamine compound constituting the imide bond unit are different. It is preferable. At least a part of Q ¹ in the above formula (A) is represented by the following formula (ii).

(Here, R ⁰¹ and R ⁰² are each independently a hydrogen atom or a monovalent organic group.)
Specific examples of the diamine compound used for the divalent organic group (Q ¹ ) include 2,7-diaminofluorene, 9,9-dimethyl-2,7-diaminofluorene, 9,9-dihexyl-2,7- Diaminofluorene, dialkylfluorene such as 9,9-dioctyl-2,7-diaminofluorene, 9,9-diphenyl-2,7-diaminofluorene, etc. (hereinafter sometimes referred to as “2,7-diaminofluorene”) Is mentioned.
2,7-diamino fluorene and the like, it can be used with the diamine to be used in describing Q ² below, the preferred amount of such 2,7-diamino fluorene is 5-100% of the ^{Q 1.}

Examples of the diamine compound used for the divalent organic group (Q ² ) include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, and 4,4′-. Diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminobenzanilide, 1,5-diamino Naphthalene, 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′-trifluoromethyl-4,4′-diaminobiphenyl, 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-amino) Phenyl) -10-hydroanthracene, 9,9-bis (4-aminophenyl) fluorene, 4,4′-methylene-bis (2-chloroaniline), 2,2 ′, 5,5′-tetrachloro-4,4′-diaminobiphenyl, 2,2′-dichloro-4,4′-diamino-5,5′-dimethoxybiphenyl, 3,3′-dimethoxy- 4,4′-diaminobiphenyl, 1,4,4 ′-(p-phenyleneisopropylidene) bisaniline, 4,4 ′-(m-phenyleneisopropylidene) bisaniline, 2,2′-bis [4- (4- Amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, 4,4′-bis [(4-amino-2-tri Aromatic diamines such as fluoromethyl) phenoxy] -octafluorobiphenyl, 4- (4′-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate;
1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1 , 4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylene methylenediamine, tricyclo [6.2.1.0 ^2,7 ] -undecylenedimethyldiamine, 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 Phenylphenanthridine, 1,4-diaminopiperazine, 3,6-diaminoacridine, bis (4-aminophenyl) phenylamine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N-ethyl -3,6-diaminocarbazole, N-phenyl-3,6-diaminocarbazole, N, N′-di (4-aminophenyl) -benzidine, and each of the following formulas (III) to (IV) A diamine having two primary amino groups and a nitrogen atom other than the primary amino group in the molecule, such as a compound;

(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 ¹ represents a divalent organic group.)

(Wherein X ² 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 there are a plurality of them. X ² may be the same or different.)
Monosubstituted phenylenediamine represented by the following formula (V); diaminoorganosiloxane 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.)

(In the formula, 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, 2,2-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) biphe 4- (4′-trifluoromethoxybenzoyloxy) cyclohexyl-3,5-diaminobenzoate, compounds represented by the above formulas (9) to (13), 2,6-diaminopyridine, 3, 4-diaminopyridine, 2,4-diaminopyrimidine, 3,6-diaminoacridine, 3,6-diaminocarbazole, N-methyl-3,6-diaminocarbazole, N-ethyl-3,6-diaminocarbazole, N- Of the compounds represented by phenyl-3,6-diaminocarbazole, N, N′-di (4-aminophenyl) -benzidine, and the above formula (III), the compound represented by the following formula (14), the above formula ( IV) Among the compounds represented by the following formula (15) and among the compounds represented by the above formula (V), among the compounds represented by the following formulas (16) to (21): The compound represented 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 0.8 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]
For the organic solvent, alcohol, ketone, ester, ether, halogenated hydrocarbon, hydrocarbon and the like, which are poor solvents for polyamic acid, can be used in combination as long as the polyamic acid to be produced does not precipitate. 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, diisobutyl ketone, isoamylpropionate, isoamylisobutyrate, diisopentyl ether, etc. In That.

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

[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 as described above. The imidized polymer used in the present invention may be partially dehydrated and ring-closed with an imidation rate of less than 100%. The “imidation ratio” here is a value representing the ratio of the repeating unit having an imide ring or an isoimide ring as a percentage in all repeating units of the polymer. An alignment film composed of an imidized polymer having an imidization ratio of 20 to 100% can be evaluated to have high image sticking and high reliability, particularly when used in a TFT type device. The polyamic acid is dehydrated and closed 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 dehydrating ring-closing catalyst to this solution, and heating as necessary. By the method.
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 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.

  The imidized polymer used in the present invention may be partially dehydrated and closed and have a low imidization rate. The imidation ratio in the imidized polymer used in the present invention is preferably 80% or more, more preferably 85% or more. Here, the “imidation rate” 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.

[Terminal modification]
The polyamic acid, and the partially imidized block polymer and the partially imidized random polymer, which are imidized polymers, may be of a terminal modified type having 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, as the acid monoanhydride, for example, maleic anhydride, phthalic anhydride, itaconic anhydride, n-decyl succinic anhydride, n-dodecyl succinic anhydride, n-tetradecyl succinic 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.

[Solution viscosity]
The polymer used in the aligning agent of the present invention preferably has a viscosity of 20 to 800 mPa · s, and preferably has a viscosity of 30 to 500 mPa · s when a 10% solution is obtained. Is more preferable.
The solution viscosity (mPa · s) of the polymer was measured at 25 ° C. using an E-type rotational viscometer for a solution diluted to a predetermined solid content concentration using a predetermined solvent.

<Liquid crystal aligning agent>
The liquid crystal aligning agent of the present invention is constituted by dissolving and containing the polymer in an organic solvent. The ratio of the repeating unit represented by the above formula (A) to the repeating unit represented by the above formula (B) in the polymer constituting the liquid crystal aligning agent of the present invention is preferably 9: 1 to 5: 5. It is.
As an organic solvent which comprises the liquid crystal aligning agent of this invention, the same thing as the solvent illustrated as what is used for the synthesis reaction of a polyamic acid can be mentioned. In addition, the same poor solvents exemplified as those that can be used together in the synthesis reaction of the polyamic acid can be appropriately selected and used together.

The solid content concentration in the liquid crystal aligning agent of the present invention is selected in consideration of viscosity, volatility and the like. Preferably it is the range of 1-10 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 film thickness of this coating film is too small. It is difficult 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 due to excessive film thickness, and the viscosity of the liquid crystal aligning agent increases, resulting in poor coating characteristics. .
The particularly preferable solid content concentration range 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 range of 1.5 to 4.5% by weight is particularly preferable. 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 ink jet 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.

Particularly preferable organic solvents used in the liquid crystal aligning agent of the present invention include, for example, 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, diisobutyl ketone (DIBK), isoamyl propionate, isoamyl isobutyrate, diisopentyl ether, etc. Can be mentioned. These can be used alone or in admixture of two or more.
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 for forming the liquid crystal alignment film of the present invention contains a compound having at least one epoxy group in the molecule (hereinafter also referred to as “epoxy group-containing compound”) from the viewpoint of improving the adhesion to the substrate surface. It is preferable that 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-4,4 ′ Diaminodiphenylmethane, N, N-diglycidyl - benzylamine, N, N-diglycidyl - such as aminomethyl cyclohexane may be mentioned as preferred. The compounding ratio of these epoxy group-containing compounds 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 polymer.

Moreover, the liquid crystal aligning agent of this invention may contain the functional silane containing compound. Examples of such functional silane-containing compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, and N- (2-aminoethyl). -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-amino Propyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl- , 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 (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane, etc. can be mentioned.
The blending ratio of these functional silane-containing compounds is preferably 40 parts by weight or less with respect to 100 parts by weight of the polymer.

<Liquid crystal display element>
The liquid crystal aligning film and 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 provided with a patterned transparent conductive film 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, glass such as float glass or soda glass; a transparent substrate made of plastic such as polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, alicyclic polyolefin, or the like 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. For patterning these transparent conductive films, a photo-etching method or a method using a mask in advance is 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-containing compound, a functional titanium-containing compound, or the like is previously applied to the surface of the substrate. You can also After applying the liquid crystal aligning agent, preheating (pre-baking) is preferably performed for the purpose of preventing dripping of the applied aligning agent. The pre-baking temperature is preferably 30 to 300 ° C, more preferably 40 to 200 ° C, and particularly preferably 50 to 150 ° C. Thereafter, a baking (post-baking) step is performed for the purpose of completely removing the solvent and heat imidizing the polyamic acid. The firing (post-bake) temperature is preferably 80 to 300 ° C, more preferably 120 to 250 ° C. Thus, 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, but further proceeds with dehydration ring closure by further heating. It can also be set as the imidized coating film. The film thickness of the formed coating film is preferably 0.001-1 μm, more preferably 0.005-0.5 μm.

(2) A rubbing process is performed in which the formed coating film surface is rubbed in a certain direction with a roll wound with a cloth made of a fiber such as nylon, rayon, or cotton. Thereby, the orientation ability of liquid crystal molecules is imparted to the coating film to form a liquid crystal orientation film.
Further, by partially irradiating the liquid crystal alignment film formed of the liquid crystal alignment agent of the present invention with ultraviolet rays as disclosed in, for example, JP-A-6-222366 and JP-A-6-281937. A resist film is partially formed on the surface of the liquid crystal alignment film that has been subjected to a treatment for changing the pretilt angle or a rubbing treatment as disclosed in JP-A-5-107544, which is different from the previous rubbing treatment. The visibility characteristics of the liquid crystal display element can be improved by removing the resist film after performing the rubbing treatment in the direction and changing the liquid crystal alignment ability of the liquid crystal alignment film.

(3) Two substrates on which the liquid crystal alignment film is formed as described above are manufactured, and the two substrates are separated by a gap (cell gap) so that the rubbing directions in the respective liquid crystal alignment films are orthogonal or antiparallel. ), And the periphery of the two substrates are bonded together using a sealant, and liquid crystal is injected and filled in the cell gap defined by the substrate surface and the sealant, and the injection hole is sealed. A liquid crystal cell is constructed. 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. Liquid crystals, biphenylcyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubane liquid crystals, 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. The imidization rate and voltage holding rate of the imidized polymer in Examples and Comparative Examples were evaluated by the following methods.

[Imidation rate]
Peaks of absorption around 1,381 cm ⁻¹ (C—N—C bending vibration = imido bond absorption) and absorption around 1,503 cm ⁻¹ (absorption of amic acid bond) in FT-IR measurement. From the area ratio, the imidization rate was calculated by the following formula,
Imidation ratio = {α ₁ / (α ₁ + α ₂ )} × 100 (%)
α _1: 1,381cm ^-1 vicinity of the absorption peak area alpha _2: peak area of absorption around 1,503Cm ^-1 Incidentally, alpha ₂ although was heated for 10 minutes on a hot plate at 300 ° C. The coating 1,503Cm ^This is a value obtained by determining the peak area with the absorption near ^-1 being 0.

[Solution viscosity]
The solution viscosity (mPa · s) of the polymer was measured at 25 ° C. using an E-type rotational viscometer for a solution diluted to a predetermined solid content concentration using a predetermined solvent.

[Voltage holding ratio]
A voltage of 5 V was applied to the liquid crystal display element with an application time of 60 microseconds and a span of 167 milliseconds, and then the voltage holding ratio after 167 milliseconds from the release of application was measured. The measuring apparatus used was VHR-1 manufactured by Toyo Corporation.

[Burn-in test]
A cell having an ITO electrode as shown in FIG. 1 was produced. A DC voltage of 6.0 V was applied to electrode A and a DC voltage of 0.5 V was applied to electrode B at room temperature for 72 hours. After releasing the stress, a DC voltage of 0.1 to 5.0 V was applied to the electrodes A and B in increments of 0.1 V. The image sticking characteristics were determined based on the luminance difference between the electrodes A and B at each voltage. When the luminance difference was large, it was judged that the image sticking characteristic was bad.

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 96 g (0.89 mol) as the diamine compound, 3 , 3 ′-(tetramethyldisiloxane-1,3-diyl) bis (propylamine) 25 g (0.10 mol) and 3,6-bis (4-aminobenzoyloxy) cholestane 13 g (0.02 mol) As a monoamine, 8.1 g (0.03 mol) of n-octadecylamine was dissolved in 960 g of N-methyl-2-pyrrolidone and reacted at 60 ° C. for 6 hours.
A small amount of the obtained polyamic acid solution was taken, NMP was added, and the viscosity was measured with a solution having a solid content concentration of 10%. As a result, it 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 was performed at 110 ° C. for 4 hours. After the imidation reaction, the solvent in the system was replaced with new γ-butyrolactone (the pyridine and acetic anhydride used for the imidation reaction were removed from the system in this operation), and the imidization with a solid content concentration of 15 wt% was performed. About 2,000 g of a polymer solution (referred to as “polyimide (A-1)”) was obtained.

Synthesis example 2
224 g (1.0 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride as tetracarboxylic dianhydride, 108 g (1.0 mol) of p-phenylenediamine as a diamine compound, and cholesteryl-3,5- 7.8 g (0.015 mol) of diaminobenzoate was dissolved in 4,500 g of N-methyl-2-pyrrolidone and reacted at 60 ° C. for 6 hours. To the obtained polyamic acid solution (427 g), 173 g of N-methyl-2-pyrrolidone was added, 23.4 g of pyridine and 18.1 g of acetic anhydride were added, and dehydration ring closure was performed at 110 ° C. for 4 hours. After the imidation reaction, the solvent in the system was replaced with new γ-butyrolactone (the pyridine and acetic anhydride used for the imidation reaction were removed from the system in this operation), and the imidization with a solid content concentration of 15 wt% was performed. About 150 g of a polymer solution (referred to as “polyimide A-2”) was obtained.

Synthesis example 3
218 g (1.0 mol) of 1,2,4,5-benzenetetracarboxylic dianhydride as tetracarboxylic dianhydride and 196 g (1.0 mol) of 2,7-diaminofluorene as a diamine compound were added to N-methyl- About 4,800 g of polyamic acid (this is referred to as “polyamic acid (B-1)”) dissolved in 4,500 g of 2-pyrrolidone and reacted at 40 ° C. for 3 hours was obtained.

Synthesis example 4
196 g (1.0 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride as tetracarboxylic dianhydride and 212 g (1 of 2,2′-dimethyl-4,4′-diaminobiphenyl as diamine compound) 0.0 mol) is dissolved in 370 g of N-methyl-2-pyrrolidone and 3,300 g of γ-butyrolactone and reacted at 40 ° C. for 3 hours (this is referred to as “polyamic acid (B-2)”) solution. About 3,700 g was obtained.

Example 1
The polyimide (A-1) obtained in Synthesis Example 1 and the polyamic acid (B-1) obtained in Synthesis Example 3 were mixed with γ-butyrolactone so that polyimide: polyamic acid = 20: 80 (weight ratio). / N-methyl-2-pyrrolidone / butyl cellosolve mixed solvent (weight ratio 71/17/12) to dissolve N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane as a polymer 100 2 parts by weight was dissolved to give a solution having a solid concentration of 3.5% by weight. After sufficient stirring, the solution was filtered using a filter having a pore size of 1 μm to prepare the liquid crystal aligning agent of the present invention. Imidation rate The above liquid crystal aligning agent is applied onto a transparent conductive film made of an ITO film provided on one surface of a 1 mm thick glass substrate using a spinner (rotation speed: 2500 rpm, application time: 1 minute) And it dried at 200 degreeC for 1 hour, and formed the film with a dry film thickness of 0.08 micrometer. When the imidization rate of this film was measured, the imidation rate was 53%. A rubbing machine having a roll in which a rayon cloth was wound around this film was subjected to a rubbing treatment at a roll rotation speed of 400 rpm, a stage moving speed of 3 cm / second, and a hair foot pushing length of 0.4 mm. The liquid crystal alignment film-coated substrate was subjected to ultrasonic cleaning for 1 minute in ultrapure water and dried in a 100 ° C. clean oven for 10 minutes. Next, after applying an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 5.5 μm to the outer edges of the pair of transparent electrodes / transparent electrode substrates having the liquid crystal alignment film of the liquid crystal alignment film coated substrate, the liquid crystal alignment film The adhesive was cured by overlapping and pressing so that the surfaces were opposed. Next, a nematic liquid crystal (MLC-6221 manufactured by Merck & Co., Inc.) was filled between the substrates from the liquid crystal injection port, and then the liquid crystal injection port was sealed with an acrylic photo-curing adhesive to produce a liquid crystal display element. The voltage holding ratio of the obtained liquid crystal display element was evaluated. The liquid crystal aligning agent obtained in the present invention showed a high voltage holding ratio of 99% or more. Moreover, when the image sticking test was conducted, good results were shown.

Comparative Examples 1-2
Polyimide (A-2) obtained in Synthesis Examples 1 and 2, polyamic acid (B-2) obtained in Synthesis Example 4 and N, N, N ′, N′-tetraglycidyl-4,4′-diamino Diphenylmethane was dissolved in a mixed solvent containing γ-butyrolactone as a main component with the composition shown in Table 1 to obtain a solution having a solid content concentration of 3.5%, and this solution was filtered with a filter having a pore size of 1 μm. The alignment agent was adjusted. 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, voltage holding ratio and image sticking characteristics were evaluated. The results are shown in Table 1.

Comparative Example 3
The polyimide (A-1) obtained in Synthesis Example 1 and the polyamic acid (B-2) obtained in Synthesis Example 4 are mainly composed of γ-butyrolactone so that polyimide: polyamic acid = 20: 80 (weight ratio). It is dissolved in a mixed solvent as a component, and 2 parts by weight of N, N, N ′, N′-tetraglycidyl-4,4′-diaminodiphenylmethane is dissolved in the polymer 100 to obtain a solid content concentration of 3.5% by weight. A liquid crystal aligning agent of the present invention was prepared by preparing a solution and filtering the solution with 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, voltage holding ratio and image sticking characteristics were evaluated. The results are shown in Table 1.

Explanatory drawing of the arrangement of the electrode of the cell produced for the burn-in test

Claims (4)

A polymer having an amic acid repeating unit represented by the following formula (A) and an imide repeating unit represented by the following formula (B), the amic acid repeating unit represented by the formula (A) and the formula (B) The ratio of the amic acid repeating unit represented by the formula (A) to the total of imide repeating units represented by: 50 to 90% by weight,
At least 1 part of the amic acid repeating unit represented by Formula (A) is represented by following formula (A-1), The liquid crystal aligning agent characterized by the above-mentioned.

In the formula, P ¹ is a tetravalent organic group and Q ¹ is a divalent organic group.

In the formula, P ² is a tetravalent organic group and Q ² is a divalent organic group.

In the formula, P ⁰ is a tetravalent aromatic group, and R ⁰¹ and R ⁰² are each independently a hydrogen atom or a monovalent organic group. The liquid crystal aligning agent of Claim 1 by which the amic acid repeating unit represented by a formula (A-1) is represented by a following formula (A-2).

In the formula, the definitions of R ⁰¹ and R ⁰² are the same as those in the above formula (A-1). The liquid crystal aligning film formed from the liquid crystal aligning agent of Claim 1 or 2. A liquid crystal display element comprising a liquid crystal alignment film formed from the liquid crystal aligning agent according to claim 1.

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