JPH0634979A - Composition for liquid crystal oriented film, production of liquid crystal oriented film, liquid crystal oriented film, liquid crystal holding substrate and liquid crystal display element - Google Patents

Abstract

PURPOSE:To increase a pretilt angle and to enable the formation of a uniform film thickness by incorporating a specific diamix compd., tetracarboxylic dianhyclride and polyamide acid as well as specific weight ratios of plural solvents into the compsn. CONSTITUTION:This compsn. contains the fluorine atom-contg. cliamine compd. expressed by formula I, the diamine compds. exclusive of the diamine compd. at need, the silicon atom-contg. tetracarboxylic dianhydride expressed by formula II and the polyamide acid obtd. by bringing the tetracarboxylic dianhydride exclusive thereof at need into reaction with the solvent A. The compsn. contains the solvent A, B at the weight ratios expressed by formula III. In the formula I, Ar1 to Ar4 denote an arom. group; R1 to R6 denote a fluorinated alkyl group; X1 and X2 denote -O-, etc. In the formula II, Ar5 and Ar6 denote an arom. group; R1 to R10 denote 1 to 10C alkyl group, etc. The solvent A is N-methyl-2- pyrrolidne, etc.. The solvent B is glycol monoether, etc.. As a result, the pretilt angle is increased to >=7 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for liquid crystal alignment film, a method for producing a liquid crystal alignment film using the same, a liquid crystal alignment film, a liquid crystal holding substrate and a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, an STN (Super Twisted Nematic) system has been used for a liquid crystal display device for a large display in order to improve visual characteristics. This is a method in which the major axis direction of the liquid crystal molecules in the cell is twisted by 200 to 270 ° (200 to 270 ° twist), and the larger the twist angle, the better the visual characteristics. In order to increase the twist angle in these STN devices, it is necessary that the angle (pretilt angle) formed by the liquid crystal molecules and the glass substrate on which the alignment film is formed is large, and specifically, 260 °. In order to obtain the above twist angle, an alignment film material having a pretilt angle of 7 ° or more is required. However, in the conventional polyimide-based alignment film, the pretilt angle could not be set to 7 ° or more.
It was put to practical use with a twist angle of around 0 °.

On the other hand, an alignment film is generally formed by applying a composition for a liquid crystal alignment film onto a substrate by a method such as spin coating or offset printing, but the thickness of the formed alignment film is partially different. Therefore, there is a problem that the threshold voltage is locally different and unevenness of brightness and darkness of the liquid crystal display element occurs, resulting in deterioration of image quality. Since a liquid crystal display device having a twist of 180 to 240 ° has a limit in improving display quality, a liquid crystal display device having a twist of 240 to 270 ° has been studied recently. 260-2 with a particularly large twist angle
The 70 ° twist liquid crystal display element has been actively studied because it can obtain the best visual characteristics in the STN type liquid crystal display element. When an alignment film having a low pretilt angle is used for the liquid crystal display element, domains are generated and display quality is deteriorated. Therefore, it is necessary to use an alignment film having a high pretilt angle in which no domain is generated. In particular, a liquid crystal display device with a twist of 260 to 270 ° requires a pretilt angle of 7 ° or more, but no conventional liquid crystal alignment film has a pretilt angle of 7 ° or more, and a liquid crystal display device with a twist of 260 to 270 ° is required. Was not suitable for. Further, the uneven brightness of the liquid crystal display element due to the non-uniform thickness of the alignment film has been a problem in achieving high display quality.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and is capable of forming a uniform film thickness with a pretilt angle of 7 ° or more, and a liquid crystal alignment film using the same. And a liquid crystal alignment film, a liquid crystal holding substrate, and a liquid crystal display device.

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly studied in view of the above-mentioned problems of the prior art. As a result, when a specific polyimide is used as a liquid crystal alignment film, the pretilt angle becomes 7 ° or more, and a uniform film is obtained. The inventors have found that a thickness can be formed and have reached the present invention. That is, the present invention provides (a) general formula (I)

[Chemical 4] (In the formula, Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ are aromatic groups,
R ₁ and R ₂ are fluorinated alkyl groups having 1 to 5 carbon atoms, R ₃ , R ₄ , R ₅ and R ₆ are fluorinated alkyl groups having 1 to 10 carbon atoms having the same or different structures, X ₁
And X ₂ represent —O— or —S—, a, b and c represent 0 or 1, and d, e, f and g represent 0 or an integer of 1 to 4. However, when all of a, b and c are 0, either or both of d and g are not 0, and when a is 0 and either or both of b and c are 1 d, e, f and g Is not 0, and d,
When all of e, f and g are 0, a will not be 0) A diamine compound having a fluorine atom represented by (b) A diamine compound other than (a) if necessary (c) General formula (II)

[Chemical 5] (In the formula, Ar ₅ and Ar ₆ are aromatic groups, R ₇ , R ₈ and R ₉
And R ₁₀ is an alkyl group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms or an aromatic group, X ₁
And X ₄ is

[Chemical 6] (N is an integer of 1 to 10), k and m are 0 or 1, and L is an integer of 0 or 1 to 5). And (d) if necessary, a polycarboxylic acid obtained by reacting a tetracarboxylic acid dianhydride other than (c) in the following solvent A and the following solvent B in a solvent weight ratio:

[Equation 2] A composition for a liquid crystal alignment film containing as, a method for producing a liquid crystal alignment film using the composition, a liquid crystal alignment film formed from the composition, facing a liquid crystal holding substrate and a liquid crystal having the alignment film, The present invention relates to a liquid crystal display device having the liquid crystal alignment film on a liquid crystal holding substrate provided with electrodes. Solvent A: N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N,
N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, tetramethylsulfone or 1,4-dioxane Solvent B: glycol monoether, glycol diether or glycol acetate

Examples of the diamine compound (a) having a fluorine atom represented by the above general formula (I) used in the present invention include, for example, 2,2-bis (4-aminophenyl)-
1,1,1,3,3,3-hexafluoropropane,
3,3-bis (4-aminophenyl) -1,1,1,
2,2,4,4,5,5,5-decafluoropentane,
2,2-bis (4-aminophenyl) -1,1,1,
3,3,4,4,4-octafluorobutane, 2,2-
Bis (3-aminophenyl) 1,1,1,3,3,3-
Hexafluoropropane, 2,2-bis {4- (4-aminophenoxy) phenyl} -1,1,1,3,3,3
-Hexafluoropropane, 2,2-bis {4- (4-
Aminophenoxy) phenyl} -1,1,1,2,2
4,4,5,5,5-decafluoropentane, 2,2-
Bis {4- (4-aminophenoxy) phenyl} -1,
1,1,3,3,4,4,4-octafluorobutane,
2,2-bis {3- (4-aminophenoxy) phenyl} -1,1,1,3,3,3-hexafluoropropane, 2,2-bis {4- (3-aminophenoxy) phenyl}- 1,1,1,3,3,3-hexafluoropropane, 2,2-bis {3- (3-aminophenoxy) phenyl} -1,1,1,3,3,3-hexafluoropropane, 2 , 2-bis {4- (4-aminophenoxy)
Phenyl} -1,1,1,3,3,3-hexafluoropropane, 4,4'-diamino-3,3'-di (trifluoromethyl) biphenyl, 4,4'-diamino-3,
3'-di (pentafluoroethyl) biphenyl, 4,
4'-diamino-3,3'-di (pentafluoropropyl) biphenyl, 4,3'-diamino-3,4'-di (trifluoromethyl) biphenyl, 3,3'-diamino-4,4'- Di (trifluoromethyl) biphenyl,
4,4'-diamino-3,3'-di (trifluoromethyl) -5,5'-di (pentafluoroethyl) biphenyl, 4,4'-bis (4-amino-3-trifluoromethylphenoxy) Biphenyl, 4,4'-bis (4-amino-3-pentafluoroethyl) biphenyl, 3,
3'-bis (4-amino-3-trifluoromethylphenoxy) biphenyl, 4,4'-bis (3-amino-4)
-Trifluoromethylphenoxy) biphenyl, 4,
4'-bis (4-aminophenoxy) -3,3'-ditrifluoromethylbiphenyl, 3,3'-bis (4-aminophenoxy) -4,4'-ditrifluoromethylbiphenyl, 4,4'-bis (4-aminophenoxy)-
3,3'-dipentafluoroethylbiphenyl, 4,
4 '-(4-aminophenoxy) -3,3'-ditrifluoromethylbiphenyl, 2,2'-bis (4-amino-3-trifluoromethylphenyl) -1,1,1,
3,3,3-hexafluoropropane, 2,2'-bis (4-amino-3-pentafluoroethyl) -1,1,
1,3,3,3-hexafluoropropane, 3,3'-
Bis (4-amino-3-trifluoromethylphenyl)
-1,1,1,2,2,4,4,5,5,5-decafluoropentane, 3,3'-bis (4-amino-3-pentafluoroethylphenyl) -1,1,1, 2, 2,
4,4,5,5,5-decafluoropentane, 2,2 '
-Bis {4- (4-aminophenoxy) -3-trifluoromethylphenyl} -1,1,1,3,3,3-hexafluoropropane, 2,2'-bis {4- (4-amino- 3-trifluoromethylphenoxy)} 1,1,
1,3,3,3-hexafluoropropane, 4,4'-
Bis (4-amino-3-trifluoromethylphenoxy) -3,3'-di (trifluoromethyl) biphenyl, 2,2'-bis {4- (4-amino-3-trifluoromethylphenoxy) phenyl} -1,1,1,3
3,3-hexafluoropropane and the like can be mentioned. These may be used alone or in combination of two or more.

The tetracarboxylic dianhydride (c) having a silicon atom represented by the above general formula (II) used in the present invention is 1,3-bis (3,4-dicarboxyphenyl) -1. , 1,3,3-Tetramethyldisiloxane dianhydride, 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3-tetraethyldisiloxane dianhydride, 1,3-bis (3,4-Dicarboxyphenyl) -1,1,3,3-tetraphenyldisiloxane dianhydride, 1,3-bis {3- (3,4-dicarboxybenzoyloxy) propyl} -1,1 , 3,3-Tetramethyldisiloxane dianhydride, 1,3-bis {2-
(3,4-Dicarboxybenzoyloxy) ethyl}-
1,1,3,3-tetramethyldisiloxane dianhydride,
1,3-bis {5- (3,4-dicarboxybenzoyloxy) pentyl} -1,1,3,3-tetramethyldisiloxane dianhydride, 1,3-bis {3- (3,4- Dicarboxybenzoyloxy) propyl} -1,1,
3,3-tetraphenyldisiloxane dianhydride, bis (3,4-dicarboxybenzoyloxy) diphenylsilane dianhydride, bis (3,4-dicarboxybenzoyloxy) dimethylsilane dianhydride, bis (3,3 4-dicarboxybenzoyloxy) ethylmethylsilane dianhydride, 1,3-bis (3,4-dicarboxyphenyl)
-1,3-Dimethyl-1,3-diethyldisiloxane dianhydride, 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3,5,5-hexamethyltrisiloxane dianhydride Anhydrous, 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3,5,5,7,7-octamethyltetrasiloxane dianhydride, 1,3-bis (3,3
4-dicarboxyphenyl) -1,1,3,3,5
5,7,7,9,9-decamethylpentasiloxane dianhydride, 1,3-bis (3,4-dicarboxyphenyl)
-1,1,3,3,5,5,7,7,9,9,11,1
Examples thereof include 1-dodecamethylhexasiloxane dianhydride, and these can be used alone or in combination of two or more.

The solvent A used in the present invention is a good solvent for the polyamic acid in the present invention. However, the polyamic acid solvent consisting only of the solvent A has a poor wettability and spreadability, and when applied to a substrate, the film thickness becomes nonuniform, and in extreme cases, cissing may occur. On the other hand, the solvent B is a solvent having good wettability, but when it is used alone, the weight ratio of the solvent A to the solvent B is changed because the polyamic acid of the present invention precipitates.

[Equation 3] In that case, the wettability can be improved without precipitating the polyamic acid, and the alignment film having a uniform film thickness can be formed. Each of the solvent A and the solvent B may be used alone or in combination of plural kinds.

As the glycol monoether of the solvent B, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, diethylene glycol. Monomethyl ether, diethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether and the like are used. As glycol diether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether,
Ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, etc. are used. As the glycol ether acetate, ethylene glycol monoacetate, ethylene glycol monomethyl ether acetate, ethylene glycol diacetate, diethylene glycol acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate or the like is used. Solvent A is used during the synthesis of the polyamic acid, but may be added after the synthesis depending on the desired concentration of polyamic acid. Solvent B is added after the synthesis of polyamic acid.

The diamine compound (a) having a fluorine atom represented by the general formula (I) and the general formula (II)
The diamine compound other than (a) and the tetracarboxylic acid dianhydride other than (c) which are optionally used together with the tetracarboxylic acid dianhydride (c) having a silicon atom represented by Not (a)
Examples of other diamine compounds include m-phenylenediamine, p-phenylenediamine, m-xylenediamine, p-xylenediamine, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane and 3,3'-dimethyl. -4,4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetramethyl-4,
4'-diaminodiphenylmethane, 2,2'-bis (4
-Aminophenyl) propane, 4,4'-methylenedianiline, benzine, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 1,
5-diaminonaphthalene, 3,3'-dimethylbenzine, 3,3'-dimethoxybenzine and the like can be mentioned.
These may be used alone or in combination of two or more.

Examples of the tetracarboxylic acid dianhydride other than (c) include, for example, pyrolimellitic dianhydride, 2,
3,6,7-naphthalenetetracarboxylic dianhydride,
3,3 ', 4,4'-diphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2', 3,3'-diphenyltetracarboxylic dianhydride , Thiophene-2,3,4,5-tetracarboxylic dianhydride, 2,2-bis (3,4-carboxyphenyl) propane dianhydride, 3,4-dicarboxyphenyl sulfone dianhydride, perylene -3, 4, 9, 10
-Tetracarboxylic acid dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 3,3 ', 4,4'
-Benzophenone tetracarboxylic acid dianhydride and the like. These may be used alone or in combination of two or more.

The polyamic acid in the present invention comprises (a) a diamine compound having a fluorine atom represented by the above general formula (I) and, if necessary, a diamine compound other than (a),
(C) It is obtained by reacting a tetracarboxylic acid dianhydride having a silicon atom represented by the general formula (II) with a tetracarboxylic acid dianhydride other than (c) in the solvent A, if necessary. In this case, the amount of the fluorine atom-containing diamine compound represented by the general formula (I) used is 0.5 mol% or more based on all diamine components, and the silicon atom represented by the general formula (II) is used. The amount of the tetracarboxylic dianhydride to be used is preferably 0.5 mol% or more with respect to the previous tetracarboxylic dianhydride, and the total number of moles of the diamine component and the tetracarboxylic dianhydride It is preferable that the total number of moles of is substantially equimolar and the reaction is performed. The concentration of the polyamic acid produced is 2 to 30% by weight, preferably 5 to
It is preferable to react the above monomers in an amount in the range of 20% by weight.

The polyamic acid obtained by the above reaction is dehydrated and ring-closed by heating (for example, 100 to 400 ° C.) and / or scientific treatment (for example, acetic anhydride treatment) to form a polyimide.

The composition for liquid crystal alignment film containing the polyamic acid of the present invention is prepared, for example, from ITO (Indium) in advance.
It is applied on a glass substrate on which a transparent electrode such as Tin Oxide) is formed, and dehydrated and ring-closed to form a polyimide layer. As a coating method, a dipping method, a printing method, a spraying method, or the like is used. The dehydration ring closure temperature is 150 to 400 ° C,
Preferably, it can be arbitrarily selected in the range of 150 to 300 ° C. The heating time is 1 minute to 6 hours, preferably 1 minute to 3 hours. A coupling agent such as a silane coupling agent or a titanium coupling agent may be used in the polyimide layer in order to improve the adhesion between the glass substrate and the polyimide layer. The polyimide layer thus formed is used as a liquid crystal alignment film by rubbing the surface. A liquid crystal display device can be obtained by a known method using a liquid crystal holding substrate having a liquid crystal alignment film. The liquid crystal alignment film obtained by using the composition for liquid crystal alignment film of the present invention is particularly suitable for a liquid crystal display element of STN method having a twist angle of 260 to 270 °.

[0015]

EXAMPLES The present invention will be described below with reference to examples. Example 1 N-methyl-2 was obtained by adding 19.44 g (0.037 mol) of 2,2-bis {4- (4-aminophenoxy) phenyl} -1,1,1,3,3,3-hexafluoropropane. −
After adding to 170 g of pyrrolidone and stirring thoroughly,
3 ', 4,4'-diphenylcarboxylic acid dianhydride 4.6
9 g (0.016 mol) and pyromellitic dianhydride 3.48 g (0.016 mol) and 1,3-bis (3,4-dicarboxyphenyl) 1,1,3,3-tetramethyldisiloxane 2.4 g of dianhydride (0.005
Mol) was added and the reaction was carried out at 50 ° C. for 5 hours, resulting in a pale yellow viscous solution. The viscosity of this solution was adjusted, and then 228 g of ethylene glycol monobutyl ether and N-methyl-2-pyrrolidone (172 g) were used to dilute the ethylene glycol monobutyl ether to 40% by weight of the total solvent. The coating solution thus prepared was applied onto two glass substrates with transparent ITO electrodes by spinner coating, heated at 250 ° C. for 1 hour to remove the solvent and dehydrate and ring-close the polyamic acid to form a polyimide layer having a thickness of 500 Å. Was formed. The surface of this layer on two glass substrates is rubbed to obtain a liquid crystal holding substrate as a liquid crystal alignment film, which is combined with two polyimide layers facing each other so that the rubbing directions are antiparallel. It is sealed with an epoxy-based sealant EN-1000 (trade name, manufactured by Hitachi Chemical Co., Ltd.), and after heating and curing at 180 ° C. for 2 hours, liquid crystal ZLI-1132 (trade name, manufactured by Merck) is sealed inside at room temperature. A liquid crystal cell was formed. Liquid crystal cell
A T _NI (71 ℃) above the temperature of the I-1132 120
After heating at 0 ° C. for 1 hour, the pretilt angle of the cell was measured using laser light, and the pretilt angle was 13.8.
And satisfied the requirement of a 270 ° twist alignment film for a liquid crystal display device. Next, a polyimide layer is formed by printing on two glass substrates on which ITO transparent electrodes are formed so as to have 640 × 200 dots by using the coating liquid UN-coater (trade name of a printer manufactured by Nakan Co., Ltd.), The surface of this layer was rubbed to give a twist angle of 27 in the same manner as above.
The liquid crystal prepared by combining the liquid crystal to be 0 °, sealing the periphery, and adding the chiral agent S-811 (trade name, manufactured by Merck & Co., Inc.) to the liquid crystal at room temperature and enclosing the liquid crystal, and heating at 120 ° C. for 1 hour was used. A display element was formed. The liquid crystal display device has a size of 640 × 2.
It was possible to drive with 00 dots, orientation defects such as domains did not occur, and there was no uneven brightness, and the display quality was high. When the film thickness of the polyimide layer formed on the glass substrate was measured at 20 points, the deviation was 4.

Example 2 2,2-bis (4-aminophenyl) -1,1,1,
3,54,3,3-hexafluoropropane 15.54g
(0.046 mol) of N-methyl-2-pyrrolidone 17
After adding to 0 g and stirring thoroughly, 3,3 ', 4,4'-
6.47 g of diphenylcarboxylic dianhydride (0.022
Mol), pyromellitic dianhydride 4.80 g (0.02
2 mol) and 1.3-g (0.002 mol) of 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3-tetraphenyldisiloxane dianhydride, and 50
When the reaction was carried out at ℃ for 5 hours, it became a pale yellow viscous solution. Using this solution, a liquid crystal cell was formed by treating in the same manner as in Example 1, and after heating at 120 ° C. for 1 hour, the pretilt angle was measured. The pretilt angle was 11.0.
It was °. Further, using this solution, a liquid crystal display element was formed in the same manner as in Example 1, but no alignment defect occurred,
There was no unevenness in light and shade, and the display quality was high.

Example 3 16.87 g (0.033 mol) of 4,4'-bis (4-amino-3-trifluoromethylphenoxy) biphenyl was added to 170 g of N-methyl-2-pyrrolidone,
After sufficiently stirring, 3.65 g of pyromellitic dianhydride
(0.017 mol) and 1,3-bis {3- (3,4
-Dicarboxybenzoyloxy) propyl} -1,
1,3,3-Tetramethyldisiloxane dianhydride 9.4
When 8 g (0.017 mol) was added and reacted at 50 ° C. for 5 hours, it became a pale yellow viscous solution. A liquid crystal cell was formed by treating this solution in the same manner as in Example 1, and after heating at 120 ° C. for 1 hour, the pretilt angle was measured. The pretilt angle was 9.0 °. Further, a liquid crystal display element was formed by using this solution in the same manner as in Example 1, but no alignment failure occurred, and there was no uneven brightness,
The display quality was high.

Example 4 2,2-bis {4- (4-aminophenoxy) phenyl} -1,1,1,3,3,3-hexafluoropropane (19.9 g, 0.038 mol) was added to N- After adding 170 g of methyl-2-pyrrolidone and stirring sufficiently,
3 ', 4,4'-diphenylcarboxylic acid dianhydride 5.5
2 g (0.019 mol), pyromellitic dianhydride 4.
09 g (0.019 mol) and 1,3-bis (3,4
When 0.49 g (0.001 mol) of -dicarboxybenzoyloxy) diphenylsilane dianhydride was added and reacted at 50 ° C for 5 hours, a pale yellow viscous solution was obtained. A liquid crystal cell was formed by treating this solution in the same manner as in Example 1, and after heating at 120 ° C. for 1 hour, the pretilt angle was measured. As a result, the pretilt angle was 9.5 °. Furthermore, a liquid crystal display element was formed using this solution in the same manner as in Example 1, but no defective alignment occurred, no uneven brightness and high display quality.

Example 5 The pale yellow viscous solution synthesized in Example 1 was treated with N-methyl-
172 g of 2-pyrrolidone and 228 g of diethylene glycol diethyl ether were used for dilution so that diethylene glycol diethyl ether was 40% by weight in the total solvent. Then, printing was performed using an UN-coater in the same manner as in Example 1 to form a polyimide layer. When the film thickness was measured at 20 points, the deviation was 5.

Example 6 The pale yellow viscous liquid synthesized in Example 1 was treated with N-methyl-
2-Pyrrolidone (172 g) and ethylene glycol monoacetate (228 g) were used to dilute the ethylene glycol monoacetate to 40% by weight of the total solvent. Then, printing was performed using an UN-coater in the same manner as in Example 1 to form a polyimide layer. When the film thickness was measured at 20 points,
The deviation was 5.

Comparative Example 1 The pale yellow viscous solution prepared in Example 1 was treated with N-methyl-
A coating solution was prepared by diluting with 400 g of 2-pyrrolidone. Printing was performed using an UN-coater in the same manner as in Example 1 to form a polyimide layer, but the unevenness of the film thickness was large by visual observation, and the film thickness was measured at 20 points as in Example 1, but the deviation was 50. And the film thickness was quite uneven. When a liquid crystal display device was formed using this coating liquid in the same manner as in Example 1, there was no alignment defect such as domains, but bright and dark unevenness was observed.

Comparative Example 2 The pale yellow viscous solution synthesized in Example 1 was treated with N-methyl-
2-pyrrolidone (115 g) and ethylene glycol monobutyl ether (285 g) were used to dilute the ethylene glycol monobutyl ether to 50% by weight of the total solvent. As a result, a white polyamic acid was deposited and did not dissolve even with stirring.

[0023]

According to the composition for liquid crystal alignment film of the present invention,
A liquid crystal alignment film having a pretilt angle of 7 ° or more can be formed. A liquid crystal display device twisted by 260 to 270 ° using the liquid crystal holding substrate having the liquid crystal alignment film does not have alignment defects such as domains, has no uneven brightness, and has high display quality.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Odagi 4-13-1, Higashimachi, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Factory

Claims (6)

[Claims] 1. (a) General formula (I): (In the formula, Ar ₁ , Ar ₂ , Ar ₃ and Ar ₄ are aromatic groups,
R ₁ and R ₂ are fluorinated alkyl groups having 1 to 5 carbon atoms, R ₃ , R ₄ , R ₅ and R ₆ are fluorinated alkyl groups having 1 to 10 carbon atoms having the same or different structures, X ₁
And X ₂ represent —O— or —S—, a, b and c represent 0 or 1, and d, e, f and g represent 0 or an integer of 1 to 4. However, when all of a, b and c are 0, either or both of d and g are not 0, and when a is 0 and either or both of b and c are 1 d, e, f and g Is not 0, and d,
When all of e, f and g are 0, a will not be 0) A diamine compound having a fluorine atom represented by (b) A diamine compound other than (a) if necessary (c) General formula (II) [Chemical 2] (In the formula, Ar ₅ and Ar ₆ are aromatic groups, R ₇ , R ₈ and R ₉
And R ₁₀ is an alkyl group having 1 to 10 carbon atoms, a substituted alkyl group having 1 to 10 carbon atoms or an aromatic group, X ₃
And X ₄ is (N is an integer of 1 to 10), k and m are 0 or 1, and L is an integer of 0 or 1 to 5). And (d) if necessary, a polycarboxylic acid obtained by reacting a tetracarboxylic acid dianhydride other than (c) in the following solvent A and the following solvent B in a solvent weight ratio of A composition for liquid crystal alignment film, which is contained as. Solvent A: N-methyl-2-pyrrolidone, N, N-dimethylformamide, N, N-diethylformamide, N,
N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphoramide, tetramethylsulfone or 1,4-dioxane Solvent B: glycol monoether, glycol diether or glycol acetate 2. The amount of the diamine compound represented by the general formula (I) used is 0.5 mol% or more with respect to all the diamine components and / or the general formula (II) with respect to all the tetracarboxylic dianhydride components. ) The amount of the tetracarboxylic dianhydride represented by the formula (1) is 0.5 mol% or more.
The composition for a liquid crystal alignment film described. 3. A surface of the liquid crystal holding substrate on which electrodes are formed,
A method for producing a liquid crystal alignment film, which comprises applying the composition for liquid crystal alignment film according to claim 1, drying and dehydration ring closure to form a polyimide layer, and then rubbing. 4. A liquid crystal alignment film formed from the composition for liquid crystal alignment film according to claim 1. 5. A liquid crystal holding substrate having a liquid crystal alignment film formed from the composition for liquid crystal alignment film according to claim 1 or 2. 6. A liquid crystal display device having a liquid crystal alignment film obtained from the composition for a liquid crystal alignment film according to claim 1 on a liquid crystal holding substrate provided with an electrode facing the liquid crystal.