JPH06347800A - Composition for liquid crystal oriented film, production of liquid crystal oriented film, liquid crystal oriented film, liquid crystal holding substrate and liquid crystal display - Google Patents

Abstract

PURPOSE:To provide a compsn. for the liquid crystal oriented film capable of controlling a pretilt angle without changing afterimage characteristics, etc., and other chracteristics by incorporating a specific compd. into a polyamide acid soln. CONSTITUTION:This compsn. for the liquid crystal oriented film is formed by incorporating the polyamide acid soln. obtd. by reacting a diamine compd. with tetracarboxylic dianhydride in a solvent, and a novolak type epoxy compd. having the structure expressed by the formula, into he compsn. In the formula, R denotes hydrogen or a 1 to 20C univalent org. group; (n) denotes an integer from 2 to 20. The novolak type epoxy compd. is not particularly limited, insofar as the compd. satisfies the formula. This compsn. for the liquid crystal oriented film is obtd. by adding the novolak type epoxy compd. having the structure expressed by the formula into the polyamide acid soln. and sufficiently mixing the soln. The amt. of the novolak type epoxy compd. to be added is preferably specified within a 0.05 to 40wt.% range of the polyamide acid from the view point the film formability of the liquid crystal oriented film.

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, a liquid crystal alignment film, a liquid crystal sandwich substrate and a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, as an alignment film for a liquid crystal display device,
For example, polyimide of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether condensation (Japanese Patent Publication No. 55-10).
No. 18), and recently, in view of the requirement for the transparency of the display element or the high pretilt angle of the liquid crystal, a polyimide intended for this purpose has been proposed (JP-A-63-25).
9515, JP-A-64-25126).

[0003]

However, with the recent trend toward higher definition of liquid crystal display devices, the liquid crystal alignment film has a display afterimage characteristic improved, a voltage holding characteristic improved, a charging characteristic improved during rubbing, etc., in addition to the pretilt angle. There has been a demand for improving various properties. Therefore, it is difficult to control only the pretilt angle without changing other characteristics such as afterimage characteristics by the method of changing the pretilt angle by introducing a side chain by changing the main chain skeleton of polyamic acid that has been conventionally used. There is.

The present invention solves the above-mentioned drawbacks of the prior art and is capable of controlling the pretilt angle without changing afterimage characteristics and other characteristics, and a liquid crystal composition using the composition. The present invention provides a method for producing an alignment film, a liquid crystal alignment film obtained from this composition, a liquid crystal sandwich substrate having this alignment film, and a liquid crystal display device.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in view of the above-mentioned problems of the prior art and found that a composition containing a novolac type epoxy in a polyamic acid solution was used as a liquid crystal alignment film. The inventors have found that the pretilt angle can be controlled without deteriorating other characteristics, and have reached the present invention.

That is, the present invention provides (1) a polyamic acid solution obtained by reacting a diamine compound and a tetracarboxylic dianhydride in a solvent, and (2) a general formula [1].

[Chemical 2] (In the formula, R represents hydrogen or a monovalent organic group having 1 to 20 carbon atoms, and n represents an integer of 2 to 20) A liquid crystal alignment containing a novolac type epoxy compound The present invention relates to a film composition, a method for producing a liquid crystal alignment film using the composition, a liquid crystal alignment film formed using the composition, a liquid crystal sandwich substrate having the alignment film, and a liquid crystal display element.

If the molecular weight of the novolac type epoxy compound is large, it will not be compatible with the polyamic acid, so n in the general formula [1] is an integer of 2 to 20. Further, R in the general formula [1] is in the above range because of its solubility in a solvent.

The novolac type epoxy compound having the structure represented by the above general formula [1] used in the present invention is not particularly limited as long as it satisfies the general formula [1]. These are known compounds, and examples thereof include ESCN-195-6, a trade name manufactured by Sumitomo Chemical Co., Ltd., and ADEKA EP-2201, a trade name manufactured by Asahi Denka Co., Ltd.
These novolak type epoxy compounds may be used alone or in combination.
Combinations of more than one species can be used.

The polyamic acid used in the present invention is not particularly limited as long as it is obtained by reacting a diamine compound and a tetracarboxylic acid dianhydride in a solvent. It is preferable that the diamine compound and the tetracarboxylic dianhydride be reacted in substantially equimolar amounts.

Examples of the diamine compound include p-phenylenediamine, m-phenylenediamine, diaminodiphenyl ether, diaminodiphenylmethane and 2,2.
-Diaminodiphenylpropane, diaminodiphenyl sulfone, diaminobenzophenone, diaminonaphthalene, diaminoterphenyl, 1,4-bis (4-aminophenoxy) benzene, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 2,2-bis (4
-(4-aminophenoxy) phenyl) -1,1,1,
Aromatic diamines such as 3,3,3-hexafluoropropane, alicyclic diamines such as diaminodicyclohexyl ether and diaminocyclohexane, aliphatic diamines such as 1,6-diaminohexane and 1,8-diaminooctane, diaminosiloxane, Examples thereof include diaminosilane, and these may be used in combination of two or more kinds.

As the tetracarboxylic dianhydride,
For example, pyromellitic dianhydride, 3,3 ', 4,4'-
Biphenyl tetracarboxylic dianhydride, 3,3 ', 4
4'-benzophenone tetracarboxylic dianhydride, 2,
3,6,7-naphthalenetetracarboxylic dianhydride,
1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-tetracarboxynaphthalene dianhydride, 2,2-bis (3,4-dicarboxyphenyl)
Propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 3,3 ', 4,4'-diphenyl Sulfone tetracarboxylic dianhydride, 3,4,9,10
-Perylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, cyclobutane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, cyclohexane tetracarboxylic dianhydride, and the like,
These may be used in combination of two or more.

Examples of the reaction solvent include N-methyl-2-pyrrolidone, N, N-dimethylformamide,
One or more of N, N-dimethylacetamide, dimethyl sulfoxide, tetramethyl sulfone, 1,4-dioxane and the like are used.

The composition for liquid crystal alignment film of the present invention is prepared by adding the polyamic acid solution obtained by the above reaction to the above-mentioned general formula [1].
It is obtained by adding a novolak type epoxy compound having a structure represented by and mixing them well.

From the viewpoint of film-forming property of the liquid crystal alignment film, the addition amount of the novolac type epoxy compound having the structure represented by the general formula [1] is in the range of 0.05 to 40% by weight with respect to the polyamic acid. Preferably.

The composition for liquid crystal alignment film according to the present invention comprises 10
A polyimide is obtained by heating to 0 to 400 ° C. and / or chemical treatment with a dehydrating agent such as acetic anhydride. An electrode is provided on the liquid crystal holding substrate on the side facing the liquid crystal, and a liquid crystal alignment film obtained from the liquid crystal alignment film composition is formed on the substrate and the electrode to obtain a liquid crystal display element.

To form the polyimide layer of the present invention on the liquid crystal substrate, the composition for the liquid crystal alignment film is previously formed, for example, ITO (Indi).
(Um Tin Oxide) is applied on a glass substrate on which a transparent electrode is formed, and then dried and dehydrated by ring closure 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-closing temperature is 100 to 400 ° C, preferably 150 to 30
It can be arbitrarily selected within the range of 0 ° 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 display substrate having a liquid crystal alignment film.

[0019]

EXAMPLES The present invention will be described below with reference to examples.

Example 1 41.1 g (0.1 mol) of 2,2-bis [4- (4-aminophenoxy) phenyl] propane was treated with N-methyl-
After adding 378 g of 2-pyrrolidone and stirring sufficiently, 10.9 g (0.05 mol) of pyromellitic dianhydride and 14.7 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride ( 0.05 mol) and added at 5 ° C for 10
After reacting for a time, it became a pale yellow viscous liquid.
ESCN195-6 (Sumitomo Chemical Co., Ltd.) 1 to this solution
0.0g (15wt%) was added and mixed well for 8 hours. The viscosity of this solution was adjusted and coated on a glass substrate on which ITO transparent electrodes were formed so as to form two 640 × 200 dots by a spinner, and heated at 250 ° C. for 30 minutes to remove the solvent and dehydrate and ring-close the polyamic acid. Perform 700 Å
The polyimide layer of was formed. The surface of this layer on two glass substrates is rubbed to obtain a liquid crystal sandwich 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 liquid crystal ZLI-22 is inside.
A liquid crystal cell was formed by enclosing 93 (trade name, manufactured by Merck & Co., Inc.). Next, in order to stabilize this liquid crystal cell, the liquid crystal ZLI-2293 was heated at 130 ° C., which is a temperature higher than T _NI (85 ° C.) for 1 hour, and the pretilt angle was measured by the crystal rotation method. Was 6.5 °, which was higher than the pretilt angle of 4.6 ° in the case where ESN195-6 was not added. Then, a polyimide layer is formed on the substrate having the ITO transparent electrode so as to form 640 × 200 dots using the above solution in the same manner as described above, and the surface thereof is rubbed. ° Assemble the cell so that it becomes a twist and put the chiral agent CB-1 inside.
The above-mentioned liquid crystal to which 5 (trade name, manufactured by Merck & Co., Inc.) was added was sealed, and an aging treatment was performed to produce a liquid crystal cell. This liquid crystal display device could be driven at 640 × 200 dots, had no defect in alignment such as domains, had good contrast, and had high display quality, and had the same characteristics as in the case where ESCN195-6 was not added.

Example 2 Liquid crystal alignment film material for STN manufactured by Hitachi Chemical Co., Ltd. LQ-
1800 (polyamic acid, resin content 14.7% by weight) 10
Adeka EP-2201 (made by Asahi Denka Kogyo) 0.74 in 0 g
g (5% by weight) was added and mixed well for 10 hours. This solution is treated in the same manner as in Example 1 to obtain 250 ° C.
After heating for 60 minutes to form a liquid crystal cell, and after aging treatment by heating at 130 ° C. for 1 hour, the pretilt angle was measured, and the pretilt angle was 8.0 °.
The pretilt angle was higher than the pretilt angle of 6.3 ° of LQ-1800. Furthermore, using this solution, Example 1
A 260 ° twist liquid crystal cell was formed in the same manner as in, but the liquid crystal cell could be driven with 640 × 200 dots,
Alignment defects such as domains did not occur, the contrast was good, and the display quality was high, and the characteristics were the same as when ADEKA EP-2201 was not added.

[0022]

When the composition for liquid crystal alignment film of the present invention is used to form a liquid crystal alignment film, the pretilt angle can be changed without changing the device characteristics of the liquid crystal display device. In addition, since the liquid crystal display device produced by using the liquid crystal display substrate having this liquid crystal alignment film has high display quality in electro-optical characteristics without causing alignment defects such as domains, the composition for liquid crystal compounded film of the present invention is It is preferably used for a liquid crystal display device having high display quality.

Claims (10)

[Claims] 1. A polyamic acid solution obtained by reacting (1) a diamine compound and a tetracarboxylic dianhydride in a solvent, and (2) a general formula [1]: (In the formula, R represents hydrogen or a monovalent organic group having 1 to 20 carbon atoms, and n represents an integer of 2 to 20) A liquid crystal alignment containing a novolac type epoxy compound Membrane composition. 2. The composition for liquid crystal alignment film according to claim 1, wherein the novolac type epoxy compound represented by the general formula [1] is contained in an amount of 0.05 to 40% by weight based on the polyamic acid. 3. A liquid crystal holding substrate, on the surface of which an electrode is formed,
A method for producing a liquid crystal alignment film, comprising applying the composition for a liquid crystal alignment film according to claim 1, drying and dehydration ring closure to form a polyimide layer, and then rubbing the polyimide layer. 4. The surface of the liquid crystal sandwich substrate on which the electrodes are formed,
A method for producing a liquid crystal alignment film, comprising applying the composition for a liquid crystal alignment film according to claim 2, drying and dehydration ring closure to form a polyimide layer, and then rubbing the polyimide layer. 5. A liquid crystal alignment film formed from the liquid crystal alignment film composition according to claim 1. 6. A liquid crystal alignment film formed from the liquid crystal alignment film composition according to claim 2. 7. A liquid crystal sandwich substrate having the liquid crystal alignment film according to claim 5. 8. A liquid crystal sandwich substrate having the liquid crystal alignment film according to claim 6. 9. A liquid crystal display device having an electrode provided on the side of a liquid crystal holding substrate facing the liquid crystal, and a liquid crystal alignment film obtained from the composition for liquid crystal alignment film according to claim 1 formed on the substrate and the electrode. 10. A liquid crystal display device having an electrode provided on a liquid crystal holding substrate on the side facing the liquid crystal, and a liquid crystal alignment film obtained from the composition for liquid crystal alignment film according to claim 2 formed on the substrate and the electrode.