JPH1073821A - Production of liquid crystal orienting film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal orienting film which has orientating ability for a liquid crystal and excellent mass productivity without producing electrostatic charges by forming a thin film which can orient liquid crystal molecules in the perpendicular direction and irradiating a thin film with linearly polarized light. SOLUTION: This method includes a process to form a thin film which can orient liquid crystal molecules in the perpendicular direction on a substrate and a process to irradiate the formed thin film with linearly polarized light beams. As for the material to form the thin film as described above, a polyamide imide acid having a skeleton selected from branched-chain or straight-chain alkyl skeletons, fluorine atoms and alicyclic skeletons can be used. To irradiate the thin film with linearly polarized light beams, light beams emitted from a light source are changed into linearly polarized light by a polarizing plate or Glan polarlzer disposed between the thin film and the light source. The irradiation angle of the linearly polarized light beams on the thin film is usually <90 deg. from the thin film surface. If the irradiation angle is 90 deg., the direction of pretilt angle of the liquid crystal molecules can not be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a liquid crystal alignment film. More specifically, the present invention relates to a method for manufacturing a liquid crystal alignment film, which can control a pretilt angle by irradiating linearly polarized light without performing a rubbing treatment.

[0002]

2. Description of the Related Art Conventionally, a nematic liquid crystal having a positive dielectric anisotropy has a sandwich structure with a substrate having a transparent electrode having a liquid crystal alignment film, and a long axis of liquid crystal molecules is continuously twisted by 90 ° or more between the substrates. TN (Twisted Nema)
2. Description of the Related Art A liquid crystal display device having a (tic) type or STN (Super Twisted Nematic) type liquid crystal cell is known. As means for aligning the liquid crystal in the liquid crystal cell, an organic film is formed on the substrate surface, and then the organic film surface is rubbed in one direction with a cloth material such as rayon to impart liquid crystal alignment capability (rubbing treatment). Method, oblique deposition of silicon oxide on the substrate surface, Langmuir-Blodgett method (LB
There is a method of forming a molecular film having a long-chain alkyl group by using the method, but there are restrictions on the size of the substrate to be processed, and in terms of processing time and processing cost, industrially, the liquid crystal by rubbing is not used. Orientation is common.

[0003]

However, when the liquid crystal is aligned by rubbing, there is a problem that static electricity is easily generated during the rubbing process. When static electricity is generated, dust adheres to the surface of the alignment film, causing display defects.
In the case of a liquid crystal cell having an ansister element, a circuit of the TFT element is destroyed by the generated static electricity, which causes a reduction in yield. Further, in a liquid crystal display device which is increasingly finer in the future, uniformity of the rubbing process becomes a problem because the pixel density is increased. Also, in order to solve the above problem, using polyvinyl cinnamate for the alignment film,
Method of aligning liquid crystal molecules by irradiating linearly polarized light (Jp
nJ Appl. Phys., 21, 2155-2164 (1992)) has been proposed, but there is a problem in that the pretilt angle obtained is small, so that poor orientation occurs in the liquid crystal display element when a voltage is applied.

An object of the present invention is to provide a method for producing a liquid crystal alignment film having a liquid crystal alignment ability which does not generate static electricity and is excellent in mass productivity. Another object of the present invention is to solve the above-mentioned conventional problems and to provide a method of manufacturing a liquid crystal alignment film having a high display quality without performing a rubbing process. Still other objects and advantages of the present invention will be apparent from the following description.

[0005]

According to the present invention, the above objects and advantages of the present invention are attained by forming a thin film for vertically aligning liquid crystal molecules on a substrate, and irradiating the formed thin film with a linearly polarized light beam. And a method for producing a liquid crystal alignment film.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. The liquid crystal alignment film of the present invention comprises a thin film for vertically aligning liquid crystal molecules. As a material for forming such a thin film, a polyamide-imide acid containing at least one skeleton selected from a branched or linear alkyl skeleton, a fluorine atom and an alicyclic skeleton, an imidized polymer thereof,
Examples thereof include polyamide, polyamic acid, its imidized polymer, acrylic resin, silicone resin, and silane coupling agent. Among these, in particular, at least one of the organic groups shown below (hereinafter, referred to as an organic group)
Also referred to as “specific organic group”. )) And / or an imidized polymer thereof are preferable because they exhibit good liquid crystal alignment over a long period of time. An aromatic group having a branched or straight-chain alkyl skeleton having 4 or more carbon atoms in a main chain or a side chain. Organic group having a fluorine atom. An aromatic group having an alicyclic skeleton having 4 or more carbon atoms in a main chain or a side chain.

The above polyamic acid and its imidized polymer can be synthesized, for example, by reacting a tetracarboxylic dianhydride with a diamine compound in an organic solvent or, if necessary, by dehydrating and ring-closing the compound. . At this time, by using a tetracarboxylic dianhydride and / or a diamine compound having a specific organic group, a polyamic acid and an imidized polymer thereof, which form a thin film for vertically aligning liquid crystal molecules, can be synthesized.

[Tetracarboxylic dianhydride] Examples of the tetracarboxylic dianhydride having a specific organic group used in the synthesis of the polyamic acid include 1,4-butanediol-bis (anhydrotrimellitate). 1,6
-Hexanediol-bis (anhydrotrimellitate), 1,8-octanediol-bis (anhydrotrimellitate), 1,10-decanediol-bis (anhydrotrimellitate), 1,12-dodecane Aromatic tetracarboxylic dianhydride having a branched or linear alkyl skeleton such as diol-bis (anhydrotrimellitate); 3,3 ', 4,4'-perfluoroisopropylidene diphthalic acid dianhydride; Tetracarboxylic dianhydride having a fluorine atom such as anhydride; 1,4-cyclohexanediol-bis (anhydrotrimellitate), 3,6
-Bis (anhydrotrimellitate) cholestane, and aromatic tetracarboxylic dianhydrides having an alicyclic skeleton such as compounds represented by the following formulas (1) to (3). These are used alone or in combination of two or more.

[0009]

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In the synthesis of the polyamic acid, another tetracarboxylic dianhydride is used in combination with the above-mentioned tetracarboxylic dianhydride having a specific organic group and / or a diamine having a specific organic group. Can be. As these other tetracarboxylic dianhydrides, for example, butanetetracarboxylic dianhydride,
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-cyclopentanetetracarboxylic dianhydride, 1,2,
4,5-cyclohexanetetracarboxylic dianhydride, 3,
3 ', 4,4'-dicyclohexyltetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 3,5,6-tricarboxynorbornane-2-
Acetic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-
1,2-dicarboxylic dianhydride, bicyclo [2.2.2]
Aliphatic and cycloaliphatic tetracarboxylic dianhydrides such as oct-7-ene-2,3,5,6-tetracarboxylic dianhydride;

1,3,3a, 4,5,9b-hexahydro-
5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione;
1,3,3a, 4,5,9b-hexahydro-5-methyl-
5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione;
1,3,3a, 4,5,9b-hexahydro-5-ethyl-
5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione;
1,3,3a, 4,5,9b-hexahydro-7-methyl-
5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione;
1,3,3a, 4,5,9b-hexahydro-7-ethyl-
5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione;
1,3,3a, 4,5,9b-hexahydro-8-methyl-
5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione;
1,3,3a, 4,5,9b-hexahydro-8-ethyl-
5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, a compound represented by the following formula (I), and a compound represented by the following formula (II) Aliphatic tetracarboxylic dianhydride having an aromatic ring such as a compound to be obtained;

[0012]

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(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 present , May be the same or different.)

Pyromellitic dianhydride, 3,3 ', 4,
4'-benzophenonetetracarboxylic dianhydride, 3,
3 ', 4,4'-biphenylsulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3 , 3 ', 4,4'-biphenylethertetracarboxylic 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) diphenyl sulfone dianhydride,
4,4'-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenyl phosphine oxide dianhydride , P-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4'-diphenyl ether dianhydride, bis (Triphenylphthalic acid) -4,4'-diphenylmethane dianhydride, ethylene glycol-bis (anhydrotrimellitate), propylene glycol-bis (anhydrotrimellitate), 2,2-bis (4-hydroxy And aromatic tetracarboxylic dianhydrides such as phenyl) propane-bis (anhydrotrimellitate). These are used alone or in combination of two or more.

Of these other tetracarboxylic dianhydrides, butanetetracarboxylic dianhydride, 1,2,
3,4-cyclobutanetetracarboxylic dianhydride, 1,3
-Dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,
2-dicarboxylic dianhydride, 1,3,3a, 4,5,9b-
Hexahydro-8-methyl-5- (tetrahydro-2,
5-dioxo-3-furanyl) -naphtho [1,2-c]
Furan-1,3-dione, bicyclo [2,2,2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 1,3,3a, 4,5,9b- Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, pyromellitic dianhydride, 3,3 ′, 4,4 ′ -Benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4'-biphenylsulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, the following formulas (4) to
The compound represented by (6) and the compound represented by the following formula (7) are preferable from the viewpoint of exhibiting good liquid crystal alignment, and particularly preferable are 1, 2, and
3,4-cyclobutanetetracarboxylic dianhydride, 1,3
-Dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- ( Tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione;
1,3,3a, 4,5,9b-hexahydro-8-methyl-
5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, pyromellitic dianhydride and a compound represented by the following formula (4) Can be mentioned.

[0016]

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[Diamine Compound] Examples of the diamine compound having a specific organic group used in the synthesis of the polyamic acid include octadecyl 3,5-diaminobenzoate, 1,4-bis (4-aminophenoxy) butane, One,
6-bis (4-aminophenoxy) hexane, 1,8-
Aromatic diamine having a branched or straight-chain alkyl skeleton such as bis (4-aminophenoxy) octane, 1,10-bis (4-aminophenoxy) decane, and 1,12-bis (4-aminophenoxy) dodecane 2,2
-Bis (4-aminophenyl) hexafluoropropane, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoro Propane, 2,
2′-bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane,
4,4′-bis [4- (4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl, a diamine having a fluorine atom such as a compound represented by the following formula (8);

[0018]

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Examples thereof include aromatic diamines having an alicyclic skeleton such as 1,4-bis (4-aminophenoxy) cyclohexane and compounds represented by the following formulas (9) to (15). These may be used alone or in combination of two or more.

[0020]

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[0021]

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In the synthesis of the above-mentioned polyamic acid, the tetracarboxylic dianhydride having the specific organic group and / or the diamine having the specific organic group are used in combination.
Other diamines can be used. Examples of these other diamines include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane,
3,3′-diaminodiphenylmethane, 3,5-diaminobenzoic acid, 4,4′-diaminodiphenylethane,
4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4'-diaminobiphenyl, 5-amino-1
-(4'-aminophenyl) -1,3,3-trimethylindane, 6-amino-1- (4'-aminophenyl)-
1,3,3-trimethylindane, 4,4′-diaminobenzanilide, 3,4′-diaminodiphenyl ether, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 2,7-diaminofluorene, 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, 2,2-bis [4- (4-aminophenoxy)
Phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] sulfone, 1,4-bis (4-
Aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) -biphenyl, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9- Bis (4-aminophenyl) -10-hydroanthracene, 9,9-bis (4
-Aminophenyl) fluorene, 4,4 '-(p-phenylenediisopropylidene) bisaniline, 4,4'-
Aromatic diamines such as (m-phenylenediisopropylidene) bisaniline;

An aromatic diamine having two amino groups bonded to an aromatic ring such as diaminotetraphenylthiophene and a hetero atom other than a nitrogen atom of the amino group;

1,1-methaxylylenediamine, 1,3-
Bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,2-ethylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine , Nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, 1,
2-diaminocyclohexane, 1,3-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylenediethylenediamine, tricyclo [6.2.1.0 ^2.7 ] -undecylene Dimethyldiamine,
Aliphatic or alicyclic diamines such as 4,4'-methylenebis (cyclohexylamine); 1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylene Diamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylenediethylenediamine , Tricyclo [6.2.
1.0 ^2.7 ] -Undecylenedimethyldiamine, 4,4 '
Aliphatic and cycloaliphatic diamines, such as methylenebis (cyclohexylamine);

A monosubstituted phenylenediamine represented by the following formula (III); a diaminoorganosiloxane represented by the following formula (IV):

[0026]

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(Wherein R ⁵ represents —O—, —COO—,
OCO-, -NHCO-, -CONH- and -CO-
And R ⁶ represents a monovalent organic group having a steroid skeleton or a trifluoromethyl group. )

[0028]

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(Wherein, R ⁷ represents a hydrocarbon group having 1 to 12 carbon atoms, a plurality of R ^{7 s} may be the same or different, p is an integer of 1 to 3, and q is 1-2
It is an integer of 0. )

Examples include the compound represented by the following formula (16). These diamine compounds can be used alone or in combination of two or more.

[0031]

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(In the formula, z is an integer of 1 to 5.)

Of these other diamine compounds,
p-phenylenediamine, m-phenylenediamine,
4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 1,5
-Diaminonaphthalene, 2,7-diaminofluorene,
4,4′-diaminodiphenyl ether, 2,2-bis [4- (4-aminophenoxy) phenyl] propane,
9,9-bis (4-aminophenyl) fluorene,
4 '-(p-phenylenediisopropylidene) bisaniline, 4,4'-(m-phenylenediisopropylidene) bisaniline, 2,2-bis [4- (4-aminophenoxy) phenyl] sulfone, 1,4- Diaminocyclohexane, 1,3-diaminocyclohexane, 4,4 '
-Methylenebis (cyclohexylamine), 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) -biphenyl, m-xylylenediamine, represented by the above formula (16) Compounds are preferred.

[Polyamic acid] The ratio of the tetracarboxylic dianhydride and the diamine compound used for the synthesis reaction of the polyamic acid is such that the total amount of the tetracarboxylic dianhydride is based on 1 equivalent of the amino group contained in all the diamine compounds. The ratio is preferably such that the acid anhydride group of the product is 0.2 to 2 equivalents, more preferably 0.3 to 1.2 equivalents. The synthesis reaction of the polyamic acid is usually carried out in an organic solvent at 0 to 150.
C., preferably at a reaction temperature of 0-100.degree. C. for 1-48 hours. The organic solvent is not particularly limited as long as it can dissolve the reactant generated in the reaction. For example, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide,
Aprotic polar solvents such as dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, and hexamethylphosphortriamide; and phenolic solvents such as m-cresol, xylenol, phenol, and halogenated phenol. The amount of the organic solvent used is usually
It is preferable that the total amount of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 30% by weight based on the total amount of the reaction solution.

The organic solvent includes alcohols, ketones, esters, and the like, which are poor solvents for polyamic acid.
Ethers, halogenated hydrocarbons, hydrocarbons and the like can be used in combination as long as the generated polyamic acid does not precipitate. Specific examples of such poor solvents include, for example, methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol,
Triethylene glycol, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, diethyl malonate, diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol monophenyl ether, ethylene glycol methyl phenyl Ether, ethylene glycol ethyl phenyl ether, 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, ethylene glycol methyl ether acetate, ethylene glycol Lumpur ethyl ether acetate, 4
-Hydroxy-4-methyl-2-pentanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2- Methyl hydroxy-3-methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate,
Methyl 3-ethoxypropionate, 3-methyl-3-methoxybutanol, 3-ethyl-3-methoxybutanol, 2-methyl-2-methoxybutanol, 2-ethyl-2-methoxybutanol, 3-methyl-3-ethoxy Butanol, 3-ethyl-3-ethoxybutanol, 2
-Methyl-2-methoxybutanol, 2-ethyl-2-
Ethoxybutanol, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene,
Examples include toluene and xylene. These may be used alone or in combination of two or more.

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

[Imidated polymer] The imidized polymer constituting the liquid crystal alignment film of the present invention can be prepared by dehydrating and ring-closing the above polyamic acid. In addition, in this specification, "imidated polymer" means polyimide and / or polyisoimide. The dehydration and ring closure of the polyamic acid can be performed by (i) heating the polyamic acid or (ii) dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration ring-closing catalyst to the solution, and heating as necessary. Done by the method.

The reaction temperature in the method (i) for heating a polyamic acid is usually from 50 to 200 ° C., preferably from 60 to 170 ° C. When the reaction temperature is lower than 50 ° C., the dehydration ring closure reaction does not proceed sufficiently, and the reaction temperature is lower than 20 ° C.
If it exceeds 0 ° C., the molecular weight of the obtained imidized polymer may decrease. On the other hand, in the above method (ii) of adding a dehydrating agent and a dehydration ring-closing catalyst to a solution of a polyamic acid, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride is used as the dehydrating agent. Can be. The amount of the dehydrating agent used is preferably 0.01 to 20 mol per 1 mol of the repeating unit of the polymer A. As the dehydration ring-closing catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, and triethylamine can be used. However, it is not limited to these. The amount of the dehydration ring-closing catalyst used is preferably 0.01 to 10 mol per 1 mol of the dehydrating agent used. In addition, as the organic solvent used for the dehydration ring closure reaction, the organic solvents exemplified as those used for the synthesis of polyamic acid can be exemplified. The reaction temperature of the dehydration ring closure reaction is usually 0 to 180 ° C, preferably 10 ° C.
１５０150 ° C. The imidized polymer can be purified by subjecting the reaction solution thus obtained to the same operation as the method for purifying a polyamic acid.

[Terminal-Modified Polymer] The polyamic acid and / or imidized polymer constituting the liquid crystal alignment film of the present invention may be a terminal-modified polymer having a controlled molecular weight. By using this terminal-modified polymer,
The coating characteristics of the thin film forming agent comprising the polymer solution 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,
and n-hexadecyl succinic anhydride. Examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine,
n-pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n
-Decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, n -Eicosylamine and the like.
In addition, examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

[Logarithmic Viscosity of Polymer] The polymer constituting the thin film forming agent used in the present invention has a logarithmic viscosity (ηln) value of preferably 0.05 to 10 dl / g, more preferably 0.05. ~ 5 dl / g. Here, the value of the logarithmic viscosity (ηln) is obtained by measuring the viscosity at 30 ° C. of a solution having a polymer concentration of 0.5 g / 100 ml using N-methyl-2-pyrrolidone as a solvent. It is obtained by the equation shown in (1).

[0041]

(Equation 1)

[Thin Film Forming Agent] The content of the polymer in the thin film forming agent used in the present invention is selected in consideration of viscosity, volatility, etc., but is preferably 0.1 to 0.1% based on the whole thin film forming agent. 20% by weight, more preferably 1 to 10% by weight
Range. That is, the thin film forming agent composed of the weight solution is applied to the substrate surface by a printing method, a spin coating method, or the like, and then dried to form a thin film as an alignment film material. If the combined content is less than 0.1% by weight, the thickness of this thin film may be too small to obtain a good liquid crystal alignment film, and if it exceeds 20% by weight, In some cases, it is difficult to obtain a good liquid crystal alignment film due to an excessively large thickness of the thin film, and the viscosity of the thin film forming agent is increased, resulting in poor coating characteristics. The organic solvent for dissolving the polymer is not particularly limited as long as it can dissolve the polymer, and examples thereof include the solvents exemplified as those used in the synthesis reaction of polyamic acid and the dehydration ring closure reaction. . In addition, the poor solvents exemplified as those which can be used together in the synthesis reaction of the polyamic acid can be appropriately selected and used in combination.

The thin film forming agent used in the present invention may contain a functional silane-containing compound or an epoxy group-containing compound from the viewpoint of improving the adhesion between the polymer and the surface of the substrate to be coated. Such functional silane-containing compounds include, for example, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane,
Aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl) -3
-Aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3-aminopropyltri Methoxysilane, N-
Ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7
-Triazadecane, 10-triethoxysilyl-1,4,
7-triazadecane, 9-trimethoxysilyl-3,6
-Diazanonyl acetate, 9-triethoxysilyl-
3,6-diazanonyl acetate, N-benzyl-3-
Aminopropyltrimethoxysilane, N-benzyl-3
-Aminopropyltriethoxysilane, N-phenyl-
3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltriethoxysilane, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxy Examples include silane. Examples of the epoxy group-containing compound include, for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 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-xylylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane and the like can be mentioned as preferable ones. The compounding ratio of these functional silane-containing compounds and epoxy group-containing compounds is usually 40 parts by weight or less, preferably 0.1 to 30 parts by weight, based on 100 parts by weight of the polymer.

[Liquid crystal display device] Using the method of the present invention,
The liquid crystal display element can be manufactured, for example, by the following method. (1) The thin film forming agent is applied to the transparent conductive film side of the substrate provided with the patterned transparent conductive film by a method such as a roll coater method, a spinner method, or a printing method, and then the coated surface is heated. Thus, a thin film is formed. Here, as the substrate, for example, float glass, glass such as soda glass, polyethylene terephthalate,
Polybutylene terephthalate, polyether sulfone,
A transparent substrate made of a plastic film such as polycarbonate can be used. The transparent conductive film provided on one surface of the substrate is NESA made of SnO _2.
A film, an ITO film made of In ₂ O ₃ —SnO _2, or the like can be used. For the patterning of these transparent conductive films, a photo-etching method, a method using a mask in advance, or the like is used. In applying the thin film forming agent, a functional silane-containing compound, titanate, or the like may be applied on the substrate and the transparent conductive film in advance to further improve the adhesion between the substrate and the transparent conductive film. it can. The heating temperature is set to 80 to 250 ° C., preferably 12
0 to 200 ° C. The thickness of the formed thin film is usually 0.001 to 1 μm, preferably 0.005 to 0.5.
μm.

(2) Then, the formed thin film is irradiated with a linearly polarized light beam, and if necessary, is further heated to 150 to 250 ° C.
To form a liquid crystal alignment film having a controlled pretilt angle. The light beam used in the present invention has a wavelength of 150 nm to 450 nm, and among them, ultraviolet light having a wavelength of 190 nm to 380 nm is preferable. Examples of the light source include a low-pressure mercury lamp, a high-pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, a xenon-mercury lamp, and an excimer laser.

To irradiate the linearly polarized light beam to the thin film,
The light beam emitted from the light source can be achieved by disposing a polarizing plate or a Gran polarizer between the thin film and the light source. The irradiation angle of the linearly polarized light beam on the thin film is usually less than 90 ° with respect to the thin film surface. If the irradiation angle is 90 °, the direction of the pretilt angle of the liquid crystal molecules cannot be controlled.
The irradiation angle and irradiation intensity of the linearly polarized light beam can be arbitrarily selected depending on the type of the polymer constituting the thin film, the magnitude of the pretilt angle to be expressed, and the like.

Further, by changing the direction of the polarization axis of the linearly polarized light beam to be irradiated, the angle of the linearly polarized light beam, and the irradiation intensity of the linearly polarized light beam, the thin film is irradiated with the linearly polarized light beam a plurality of times, so that the orientation of the liquid crystal molecules is improved. By changing the direction and the pretilt angle in the plane of the liquid crystal alignment film, it is possible to improve the viewing angle characteristics of the liquid crystal display device.

(3) Two substrates on which a liquid crystal alignment film is formed are irradiated with the linearly polarized light beam as described above, and the two substrates are oriented such that the polarization axes of the respective liquid crystal alignment films are orthogonal or antiparallel. The substrates are opposed to each other with a gap (cell gap) therebetween, and the peripheral portions of the two substrates are bonded to each other using a sealant. The surface of the substrate and the cell gap defined by the sealant are filled with liquid crystal, and a filling hole is formed. To form a liquid crystal cell. Then, a polarizing plate is provided on the outer surface of the liquid crystal cell, that is, on the other surface side of each substrate constituting the liquid crystal cell, and the polarization direction thereof coincides with the polarization axis direction of the liquid crystal alignment film formed on one surface of the substrate. A liquid crystal display element is obtained by sticking them at right angles. As the sealant, for example, an epoxy resin containing a hardening agent and aluminum oxide spheres as a spacer can be used.

As the liquid crystal, nematic liquid crystal,
Smectic liquid crystals can be mentioned, among which nematic liquid crystals are preferable.For example, Schiff base liquid crystals, azoxy liquid crystals, biphenyl liquid crystals, phenylcyclohexane liquid crystals, ester liquid crystals, terphenyl liquid crystals, biphenylcyclohexane liquid crystals, pyrimidine Liquid crystal, dioxane liquid crystal, bicyclooctane liquid crystal, cubane liquid crystal, and the like are used. In addition, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonaate and cholesteryl carbonate, and chiral agents sold under the trade names “C-15” and “CB-15” (manufactured by Merck & Co.) It can also be used by adding it. In addition, ferroelectric liquid crystals such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate can be used. Also,
As a polarizing plate used outside the liquid crystal cell, a polarizing plate formed by sandwiching a polarizing film called an H film absorbing iodine with a cellulose acetate protective film or a H film itself while stretching and aligning polyvinyl alcohol is used. And the like.

[0050]

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 evaluation method for each liquid crystal display device manufactured by the following Examples and Comparative Examples is described below.

[Orientation of Liquid Crystal] The presence or absence of abnormal domains in the liquid crystal cell when the voltage was turned on / off in the liquid crystal display element was observed with a polarizing microscope, and the case where there was no abnormal domain was judged as “good”. [Pretilt Angle of Liquid Crystal Display Element] The pretilt angle of the liquid crystal display element is described in [TJ Schffer et al., J. Appl. Phys., 1
9, 2013 (1980)], and measured by a crystal rotation method using He-Ne laser light.

Synthesis Example 1 224.17 g (1.00 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride and 520.78 g (1.00 mol) of the diamine represented by the above formula (12) were added to N −
It was dissolved in 2800 g of methyl-2-pyrrolidone, and this solution was reacted at 60 ° C. for 6 hours. Next, the obtained reaction solution was poured into a large excess of pure water to precipitate a reaction product.
Thereafter, the solid matter was separated, washed with pure water, and reduced pressure at 40 ° C.
For 15 hours, the logarithmic viscosity (ηln)
0.76 dl / g of polyamic acid (A-1) 692.8
g was obtained. Synthesis Example 2 Polyamic acid (A-1) obtained in Synthesis Example 1 30.0
g in 570 g of N-methyl-2-pyrrolidone,
33.3 g of pyridine and 25.8 g of acetic anhydride were added, followed by dehydration and ring closure at 110 ° C. for 3 hours. Next, 28.0 g of an imidized polymer (B-1) having a logarithmic viscosity (ηln) of 0.75 dl / g was obtained by performing precipitation, separation, washing and drying of the reaction product in the same manner as in Synthesis Example 1. Obtained.

Synthesis Example 3 In Synthesis Example 1, 224.17 (1.00 mol) of 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride was used as the tetracarboxylic dianhydride. In the same manner as in Synthesis Example 1 except that the logarithmic viscosity (ηln) was
692.7 g of 68 dl / g polyamic acid (A-2)
I got Synthesis Example 4 Logarithmic viscosity (ηln) was obtained in the same manner as in Synthesis Example 1 except that octadecyl 3,5-diaminobenzoate 404.64 (1.00 mol) was used as the diamine.
0.66 dl / g of polyamic acid (A-3) 565.8
g was obtained.

Example 1 (1) Preparation of Thin Film Forming Agent 5.0 g of polyamic acid (A-1) obtained in Synthesis Example 1
Was dissolved in N-methyl-2-pyrrolidone to obtain a solution having a solid concentration of 4% by weight, and this solution was filtered with a filter having a pore size of 1 μm to prepare a thin film forming agent.

(2) Production of Liquid Crystal Display Element IT provided on one surface of a glass substrate having a thickness of 1.1 mm
The thin film forming agent of the present invention is applied on a transparent conductive film composed of an O film using a printing machine for applying a liquid crystal alignment film,
After drying for a time, a thin film was formed. The surface of the formed thin film was irradiated with a light from a high-pressure mercury lamp through a Glan polarizer at an angle of 45 ° to the thin film. As described above, two liquid crystal alignment film forming substrates irradiated with the linearly polarized light beam are prepared, and the outer edge of each substrate is
After screen-printing an epoxy resin containing aluminum oxide spheres having a diameter of 17 μm, the two substrates are arranged to face each other with a gap therebetween so that the polarization axes of linearly polarized light beams in the respective liquid crystal alignment films are antiparallel. The outer edges were brought into contact with each other and pressed to cure the adhesive. The nematic liquid crystal “MLC-200” is placed in the cell gap defined by the adhesive on the surface of the substrate and the outer edge.
1 "(Merck Japan Ltd.)
The injection hole was sealed with an epoxy adhesive to form a liquid crystal cell. Thereafter, a polarizing plate was attached to the outer surface of the liquid crystal cell such that the polarization direction coincided with the polarization axis of the linearly polarized light in the liquid crystal alignment film formed on one surface of the substrate, thereby producing a liquid crystal display device. The irradiation energy amount (measured at 254 nm) of the linearly polarized light beam is 0 to 10 J / cm.
Fig. 1 shows the pretilt angle of the liquid crystal display element when it is varied to ² .
Shown in In addition, the liquid crystal alignment of the liquid crystal display device irradiated with the linearly polarized light was good.

Example 2 A liquid crystal display device was prepared in the same manner as in Example 1 except that the imidized polymer (B-1) was used instead of the polyamic acid (A-1). The irradiation energy amount (measured at 254 nm) of the linearly polarized light beam is 0 to 10 J /
FIG. 2 shows the pretilt angle of the liquid crystal display element when the amount was varied to cm ² . In addition, the liquid crystal alignment of the liquid crystal display device irradiated with the linearly polarized light was good.

Example 3 A liquid crystal display device was produced in the same manner as in Example 1, except that the polyamic acid (A-2) was used instead of the polyamic acid (A-1). The irradiation energy amount (measured at 254 nm) of the linearly polarized light beam is 0 to 10 J /
FIG. 3 shows the pretilt angle of the liquid crystal display element when the variable amount was changed to cm ² . In addition, the liquid crystal alignment of the liquid crystal display device irradiated with the linearly polarized light was good. Example 4 A liquid crystal display device was produced in the same manner as in Example 1, except that the polyamic acid (A-3) was used instead of the polyamic acid (A-1). The irradiation energy amount (measured at 254 nm) of the linearly polarized light beam is 0 to 10 J /
FIG. 4 shows the pretilt angle of the liquid crystal display element when the variable amount was changed to cm ² . In addition, the liquid crystal alignment of the liquid crystal display device irradiated with the linearly polarized light was good.

Reference Example 1 In Example 1, polyvinyl cinnanate was used in place of the polyamic acid (A-1), and the coating was dried at 100 ° C.
A liquid crystal display device was manufactured in the same manner as in Example 1 except that the above was performed. Irradiation energy of linearly polarized light (254 nm
Was measured, the liquid crystal display element was varied from 0 to 10 J / cm ^2. However, no pretilt angle was exhibited, and poor alignment of liquid crystal molecules was observed when voltage was applied.

[0059]

According to the present invention, there is provided a method for producing a liquid crystal alignment film which provides a liquid crystal display device having a high display quality without performing a rubbing treatment and thus without generating static electricity. The liquid crystal display device manufactured by using the method for manufacturing a liquid crystal alignment film of the present invention includes a TN type liquid crystal display device,
By selecting the liquid crystal to be used, the IPS (In P
lane switching) type, STN (SUPE)
r Twisted Nematic, SH (Su
per Homeotropic) type, OCB (Opt
allyly Compensated Birefr
Intense type, ferroelectric and antiferroelectric liquid crystal display devices and the like can be suitably used. Further, the liquid crystal display device having the liquid crystal alignment film obtained by the method of the present invention has excellent liquid crystal alignment and reliability, and can be effectively used for various devices. For example, a desk calculator, a wristwatch, a clock, a coefficient display plate, a word processor Used for display devices such as personal computers and liquid crystal televisions.

[Brief description of the drawings]

FIG. 1 shows the dependence of the pretilt angle on the irradiation energy amount of a linearly polarized light beam in Example 1.

FIG. 2 shows the dependence of the pretilt angle on the irradiation energy amount of a linearly polarized light beam in Example 2.

FIG. 3 shows the dependence of the pretilt angle on the irradiation energy of a linearly polarized light beam in Example 3.

FIG. 4 shows the dependence of the pretilt angle on the irradiation energy amount of a linearly polarized light beam in Example 4.

Claims (1)

[Claims] 1. A method for producing a liquid crystal alignment film, comprising: forming a thin film for vertically aligning liquid crystal molecules on a substrate; and irradiating the formed thin film with a linearly polarized light beam.