JPH06194671A - Composition for liquid crystal oriented film, production of liquid crystal oriented film, liquid crystal oriented film, liquid crystal clamping substrate and liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide a composition for the liq. crystal oriented film capable of changing the pretilt angle without changing the characteristic of a liq. crystal display element. CONSTITUTION:This composition for the liq. crystal oriented film contains (1) a polyamic acid soln. obtained by allowing a diamine compd. to react with tetracrboxylic dianhydride in a solvent and (2) a diamine compd. shown by the general formula (where n is an integer of 4 to 18). A liq. crystal oriented film, etc., are formed by using the composition.

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 holding 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).

However, with the recent trend toward higher definition of liquid crystal display devices, it is required for the liquid crystal alignment film to improve various characteristics other than the pretilt angle, such as display afterimage characteristics, voltage holding characteristics, and charging characteristics during rubbing. It has started to be done. Therefore, in the method of changing the pretilt angle by introducing a side chain into the main chain skeleton of polyamic acid that has been conventionally used, afterimage characteristics,
It has become difficult to control only the pretilt angle without changing other characteristics.

[0004]

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

[0005]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted intensive studies in view of the above-mentioned problems of the prior art, and as a result, when a composition containing a specific diamine compound in a polyamic acid solution was used, other characteristics were obtained. The present invention has been achieved by finding that the pretilt angle can be controlled without lowering it.

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, n represents an integer from 4 to 18) A composition for a liquid crystal alignment film containing a diamine compound, a method for producing a liquid crystal alignment film using the composition, and the composition The present invention relates to a liquid crystal alignment film formed by the above method, a liquid crystal holding substrate having the alignment film, and a liquid crystal display element.

From the viewpoints of orientation stability and changes in the pretilt angle, n of the diamine compound represented by the general formula [1] is an integer from 4 to 18.

Examples of the diamine compound represented by the above general formula [1] used in the present invention include 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane and 1,7-. Diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-
Diaminodecane, 1,11-diaminoundecane, 1,
12-diaminododecane, 1,13-diaminotridecane, 1,14-diaminotetradecane, 1,15-diaminopentadecane, 1,16-diaminohexadecane,
1,17-diaminoheptadecane, 1,18-diaminooctadecane, etc., which may be used alone or
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, Diaminosilane etc. are mentioned. You may use the diamine compound represented by General formula [1]. These can also be used in combination of two or more.

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 (3,4carboxyphenyl) propane dianhydride, 2, 2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride , 3,4,9,10-perylenetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexanetetracarboxylic dianhydride, etc. And two or more of these may be used in combination.

As the reaction solvent, for example, N-methyl-2-pyrrolidone, N, N-dimethylformamide,
N, N-dimethylacetamide, dimethyl sulfoxide, tetramethyl sulfone, 1,4-dioxane and the like are used alone or in combination of two or more kinds.

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 the diamine compound represented by and mixing them well.

From the viewpoint of the film-forming property of the liquid crystal alignment film, the amount of the diamine compound represented by the general formula [1] added is preferably in the range of 0.05 to 40% by weight based on the polyamic acid.

The composition for liquid crystal alignment film according to the present invention is 100
A polyimide is obtained by heating to ˜400 ° C. and / or chemical treatment with a dehydrating agent such as acetic anhydride. An electrode is provided on the side of the liquid crystal holding substrate 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 above composition for a liquid crystal alignment film is prepared in advance by using, for example, ITO (I
It is carried out by coating a glass substrate on which a transparent electrode such as ndium tin oxide) is formed, followed by drying and dehydration 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 400 ° C.
It can be arbitrarily selected within the range of 300 ° C. The heating time is 1 minute to 6 hours, preferably 1 minute to 3 hours.

In the polyimide layer of the present invention, a coupling agent such as a silane coupling agent or a titanium coupling agent may be used 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]

In the polyimide of the present invention, since the specific diamine compound is added to the polyamic acid, it is considered that the pretilt angle can be controlled without deteriorating the characteristics peculiar to the polyamic acid. .

[0020]

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.
To this solution, 10.0 g (15% by weight) of 1,4-diaminobutane was added and thoroughly mixed for 8 hours. The viscosity of this solution was adjusted, and the solution was applied onto two glass substrates with ITO by a spinner and heated at 250 ° C. for 30 minutes to remove the solvent and dehydrate and ring-close the polyamic acid to form a 700 Å polyimide layer. 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 anti-parallel, and the surroundings. A liquid crystal cell was formed by sealing with an epoxy sealant EN-1000 (trade name, manufactured by Hitachi Chemical Co., Ltd.) and enclosing liquid crystal ZLI-2293 (trade name, manufactured by Merck & Co., Inc.) therein. Next, in order to stabilize this liquid crystal cell, liquid crystal ZL is used as an aging treatment.
130, which is the temperature above T _NI (85 ° C) of I-2293
After heating at ℃ for 1 hour, the pretilt angle was measured by the crystal rotation method. The pretilt angle was 5.4.
And the pretilt angle was higher than the pretilt angle of 4.6 ° in the case where 10.0 g (15% by weight) of 1,4-diaminobutane was not added. Then, using the above solution, the same method as described above was performed to obtain 640 × 200 dots.
A polyimide layer is formed on the substrate on which the TO transparent electrode is formed, and the surface of the polyimide layer is rubbed.
A cell was assembled so as to have a twist of 0 °, the above liquid crystal to which a chiral agent CB-15 (trade name, manufactured by Merck & Co., Inc.) was added, and the liquid crystal display element was manufactured by performing aging treatment. The liquid crystal display device was capable of being driven by 640 × 200 dots, had good contrast and good display quality without causing alignment defects such as domains, and the display device characteristics were the same as when no addition was made.

Example 2 Liquid crystal alignment film material for STN manufactured by Hitachi Chemical Co., Ltd. LQ-
1800 (polyamic acid solution, resin content 14.7% by weight)
0.74 g (5% by weight) of 1,9-diaminononane was added to 100 g, and they were sufficiently mixed for 10 hours. This solution was treated in the same manner as in Example 1 and heated at 250 ° C. for 60 minutes to form a liquid crystal cell, which was then aged by heating at 130 ° C. for 1 hour, and then the pretilt angle was measured. , The pretilt angle is 7.3 °, and LQ-18
The pretilt angle was higher than the pretilt angle of 6.3 ° when 00 was used. Further, using this solution, a liquid crystal display device having a 260 ° twist was formed in the same manner as in Example 1. The liquid crystal display device could be driven at 640 × 200 dots, and alignment defects such as domains did not occur, resulting in contrast. The display quality was good, and the display element characteristics were the same as those without addition.

[0023]

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. Further, since the liquid crystal display device produced using the liquid crystal holding 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 alignment film of the present invention is It is preferably used for a liquid crystal display device having high display quality.

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

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]: A composition for a liquid crystal alignment film comprising a diamine compound represented by the formula (n represents an integer from 4 to 18). 2. The composition for liquid crystal alignment film according to claim 1, wherein the diamine 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 surface of the liquid crystal holding substrate on which 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 1, drying and dehydration ring closure to form a polyimide layer, and then rubbing the polyimide layer. 4. A surface of the liquid crystal holding substrate on which 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 holding substrate having the liquid crystal alignment film according to claim 5. 8. A liquid crystal holding substrate having the liquid crystal alignment film according to claim 6. 9. A liquid crystal display device comprising 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 a liquid crystal alignment film according to claim 1 formed on the substrate and the electrode. 10. A liquid crystal display device comprising 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 a liquid crystal alignment film according to claim 2 formed on the substrate and the electrode.