JPH07218920A - 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 prevent fluctuation in pretilt angle in aging after liquid crystal encapsulation by incorporating a specific polyamide acid into a compsn. for liquid crystal oriented films. CONSTITUTION:The polyamide acid obtd. by bringing (1) a diamine having a bicyclic alicyclic hydrocarbon group copossessing >=3 atoms of 7 to 9c or its derived group, (2) an aliphat. tetracarboxylic dianhydride and (3) diamines exclusive of (1) at need into reaction is incorporated into the compsn. described above. The polyamide acid to be incorporated into such compsn. for the liquid crystal oriented films is heated to 100 to 400 deg.C and/or is subjected to a chemical treatment by a dehydrating agent such as acetic anhydride and is thereby made into a polyimide. The surfaces of the substrates clamping the liquid crystals are provided with electrodes on the side facing the liquid crystals and the liquid crystal oriented films obtd. from the compsn. for the liquid crystal oriented films are formed on such substrates and electrodes, by which the liquid crystal display element is obtd.

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).

[0003]

However, with the recent increase in the size of liquid crystal display devices, the pretilt angle of the current alignment film fluctuates due to aging near the nematic-isotropic transition temperature (T _NI ) after liquid crystal encapsulation. , And the display quality was degraded.

The present invention solves the above-mentioned drawbacks of the prior art,
Composition for liquid crystal alignment film in which domain does not occur and pretilt angle does not change by aging after liquid crystal encapsulation, method for producing liquid crystal alignment film using this composition, liquid crystal alignment film obtained from this composition, and alignment film A liquid crystal holding substrate and a liquid crystal display device having the above.

[0005]

Means for Solving the Problems 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 specific polyimide is used as a liquid crystal alignment film, a domain does not occur,
The inventors have found that the pretilt angle does not change due to aging after the liquid crystal is sealed, and have reached the present invention.

That is, according to the present invention, (1) the carbon number is 7 to 9
A diamine having a bicyclic alicyclic hydrocarbon group or a derivative group thereof that shares three or more atoms, (2) an aromatic tetracarboxylic dianhydride, and (3) if necessary (1)
Composition for liquid crystal alignment film containing polyamic acid obtained by reacting diamine other than the above, method for producing liquid crystal alignment film using this composition, liquid crystal alignment film formed using this composition, and alignment film The present invention relates to a liquid crystal holding substrate and a liquid crystal display element.

The diamine having a bicyclic alicyclic hydrocarbon group or a derivative thereof having 3 or more carbon atoms having 7 to 9 carbon atoms used in the present invention is 2,3-diaminobicyclo [2 , 2,1] Heptane, 2,5-diaminobicyclo [2,2,1] heptane, 2,6-diaminobicyclo [2,2,1] heptane, 2,7-diaminobicyclo [2,2,1] Heptane, 2,3-diamino-7-azabicyclo [2,2,1] heptane, 2,5-diamino-7-azabicyclo [2,2,1] heptane, 2,6-
Diamino-7-azabicyclo [2,2,1] heptane,
2,3-Diamino-7-oxabicyclo [2,2,1]
Heptane, 2,5-diamino-7-oxabicyclo [2,2,1] heptane, 2,6-diamino-7-oxabicyclo [2,2,1] heptane, 2,3-diamino-7-thiabicyclo [ 2,2,1] Heptane, 2,5-
Diamino-7-thiabicyclo [2,2,1] heptane,
2,6-diamino-7-thiabicyclo [2,2,1] heptane, 2,3-diaminobicyclo [2,2,2] octane, 2,5-diaminobicyclo [2,2,2] octane, 2, 6-diaminobicyclo [2,2,2] octane, 2,5-diaminobicyclo [2,2,2] octane-7ene, 2,5-diamino-7-azabicyclo [2,2]
2,2] octane, 2,5-diamino-7-oxabicyclo [2,2,2] octane, 2,5-diamino-7-
Thiabicyclo [2,2,2] octane, 2,6-diamino-bicyclo [3,2,1] octane, 2,6-diamino-7-azabicyclo [3,2,1] octane, 2,6
-Diamino-7-oxabicyclo [3,2,1] octane, 2,6-diamino-7-thiabicyclo [3,2,2]
1] octane, 2,6-diaminobicyclo [3,2,2]
2] nonane, 2,6-diamino-bicyclo [3,2,2]
2] nonane-8ene, 2,6-diamino-8-azabicyclo [3,2,2] nonane, 2,6-diamino-8-oxabicyclo [3,2,2] nonane, 2,6-diamino- 8-thiabicyclo [3,2,2] nonane and the like can be mentioned. These may be used in combination of two or more. The reason why the number of carbon atoms of this diamine is set to 7 to 9 is that a polymer having a small structural change due to temperature can be obtained in this range.

In the present invention, a derivatized group in which a bicyclic alicyclic hydrocarbon group is alkyl-substituted can also be used, and for example, 2,5-diamino-7-methylbicyclo [2,2,2].
1] Heptane, 2,6-diamino-7-ethylbicyclo [2,2,2] octane and the like. These are 2
You may use together 1 or more types.

The number of moles of the diamine having a bicyclic alicyclic hydrocarbon group having 3 or more carbon atoms having 7 to 9 carbon atoms or a derivative thereof used in the present invention is the same as that of the diamine used in the reaction. It is preferably 50% or more of the number of moles.

The aromatic tetracarboxylic dianhydride used in the present invention includes 1,2,4,5-benzenetetracarboxylic dianhydride and 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride. Anhydrous, 3,3 ', 4,4'-
Biphenyltetracarboxylic dianhydride, 2,3,3 ',
4'-biphenyltetracarboxylic dianhydride, 1,4
5,8-naphthalenetetracarboxylic dianhydride, 2,
Examples thereof include 3,6,7-naphthalenetetracarboxylic acid dianhydride and oxydiphthalic acid dianhydride, and these can be used in combination of two or more kinds.

The diamine other than the above diamine having a bicyclic alicyclic hydrocarbon group or a derivative thereof is not particularly limited, and 4,4'-diaminodiphenyl ether, 1,4-diaminobenzene, 2,2 -Bis (4-
(4-Aminophenoxy) phenyl) propane, 1,6-
Diaminohexane, 1,8-diaminooctane, 1,1
0-diaminodecane, 1,12-diaminododecane,
1,4-diaminocyclohexane, 4,4'-diaminodiphenylmethane, 1,3-diaminobenzene, 2,2
-Bis (4- (4-aminophenoxy) phenyl)-
1,1,1,3,3,3-hexafluoropropane,
1,4-bis (2- (4-aminophenyl) propyl)
Benzene, 1,3-bis (2- (4-aminophenyl)
Propyl) benzene, bis (4- (4-aminophenoxy) phenyl) sulfone, bis (3- (4-aminophenoxy) phenyl) sulfone, bis (4- (3-aminophenoxy) phenyl) sulfone and the like, These may be used in combination of two or more.

In the present invention, the sum total of the number of moles of the diamines (1) and (3) and the sum total of the number of moles of the tetracarboxylic dianhydride of the above (2) are set to be approximately equimolar. It is preferable to react.

The above (1) diamine having a bicyclic alicyclic hydrocarbon group having 3 to 9 carbon atoms and sharing three or more atoms or a derivative thereof, and (2) aromatic tetracarboxylic dianhydride. And optionally a diamine other than (3) and (1) are dissolved in an inert solvent and reacted to give a polyamic acid. The reaction temperature is preferably -30 ° C to 100 ° C, and the reaction time is preferably 30 minutes to 48 hours.

As the inert solvent, it is not necessary to dissolve all of the above-mentioned monomers, but it is preferable to dissolve the produced polyamic acid, for example, N-methyl-2-pyrrolidone, N, N-dimethyl. One or more of formamide, N, N-dimethylacetamide, dimethyl sulfoxide, tetramethyl sulfone, 1,4-dioxane and the like are used. In addition to these solvents, a solvent for improving the wettability to the glass substrate can be added before or after the reaction. As these solvents, for example, butyl cellosolve, butyl cellosolve acetate, xylene, toluene and the like are used.

The polyamic acid contained in the composition for liquid crystal alignment film according to the present invention is made into a polyimide by heating it at 100 to 400 ° C. and / or chemically treating it 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 composition for liquid crystal alignment film containing the inert solvent used in the reaction is previously prepared, for example, from ITO (Indium Tin Oxid).
It is carried out by applying a transparent electrode such as e) on a glass substrate on which a transparent electrode 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. Dehydration ring closure temperature is 100-400
C., preferably 150 to 300.degree. C., can be arbitrarily selected. The heating time is 1 minute to 6 hours, preferably 1 minute to 3 hours.

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.

[0018]

EXAMPLES The present invention will be described below with reference to examples. Example 1 2,5-Diaminobicyclo [2,2,1] heptane 1
After adding 225 g of N-methyl-2-pyrrolidone to 0.4 g (0.1 mol) and stirring sufficiently, 3,3 ', 4,4
29.4 g of 4'-biphenyltetracarboxylic dianhydride
(0.1 mol) was added, and the mixture was reacted at room temperature for 6 hours, resulting in a pale yellow viscous liquid. The viscosity of this solution is adjusted, and the solution is applied onto a glass substrate on which an ITO transparent electrode is formed so as to form two 640 × 200 dots by a spinner,
The mixture was heated at 250 ° C. for 60 minutes to remove the solvent and dehydrate and ring-close the polyamic acid to form a 600 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. Epoxy sealant E
N-1000 (trade name manufactured by Hitachi Chemical Co., Ltd.) is used to assemble the cell, and liquid crystal ZLI-2293 (trade name manufactured by Merck) is sealed to form a liquid crystal cell, and a pretilt angle is set by a crystal rotation method. When measured, the pretilt angle was 3.3 °. In addition, this liquid crystal cell is
LI-2293 T _NI (85 ° C) or higher 13
After heating at 0 ° C. for 1 hour, the pretilt angle was measured.
There was almost no change at 2 °. Next, a liquid crystal alignment film is formed by the same method as described above, and two polyimide layers are opposed to each other so as to form a 240 ° twist, and an epoxy sealant EN-1000 (a product manufactured by Hitachi Chemical Co., Ltd.) Liquid crystal ZL in which a cell is assembled by sealing with a chiral agent CB-15 (trade name, manufactured by Merck & Co., Inc.)
A liquid crystal display device was prepared by enclosing I-2293 (trade name, manufactured by Merck & Co., Inc.). Next, in order to stabilize this liquid crystal display element, it was heated at 130 ° C. for 1 hour as an aging treatment. The liquid crystal display device could be driven at 640 × 200 dots, alignment defects such as domains did not occur, the contrast was good, and the display quality was high.

Example 2 2,5-Diamino-7-methylbicyclo [2,2,1]
220 g of N-methyl-2-pyrrolidone was added to 8.3 g (0.07 mol) of heptane and 6.0 g (0.03 mol) of 4,4'-diaminodiphenyl ether, and after sufficiently stirring, 3,3 ', 29.4 g (0.10 mol) of 4,4'-biphenyltetracarboxylic dianhydride was added, and 2
When reacted at 0 ° C. for 5 hours, a yellow viscous liquid was formed. The pretilt angle was 3.5 ° when the pretilt angle was measured by treating this solution in the same manner as in Example 1.
After heating this liquid crystal cell at 130 ° C. for 1 hour, the pretilt angle was measured, but it was 3.6 °, and there was almost no change in the pretilt angle. Further, using this solution, a liquid crystal display device was prepared in the same manner as in Example 1. The liquid crystal display device,
It was possible to drive at 640 × 200 dots, orientation defects such as domains did not occur, and the contrast was good and the display quality was high.

[0020]

INDUSTRIAL APPLICABILITY When a liquid crystal alignment film is formed from the composition for liquid crystal alignment film of the present invention and a liquid crystal display substrate having the liquid crystal alignment film is used to prepare a liquid crystal display element, no domain is generated and the STN A liquid crystal display device of the type can be produced. Further, since the pretilt angle does not change due to aging after the liquid crystal is filled, the display quality does not deteriorate, and the STN liquid crystal display device of high display quality can be manufactured by the composition for liquid crystal alignment film of the present invention.

Claims (6)

[Claims] 1. A diamine having (1) a bicyclic alicyclic hydrocarbon group having 7 to 9 carbon atoms and sharing three or more atoms or a derivative thereof, (2) an aromatic tetracarboxylic dianhydride. And (3) a composition for a liquid crystal alignment film, which comprises a polyamic acid obtained by reacting a diamine other than (1) as necessary. 2. The number of moles of a diamine having a bicyclic alicyclic hydrocarbon group or a derivative thereof having a carbon number of 7 to 9 and sharing three or more atoms is 50% or more of the number of moles of the diamine. The composition for liquid crystal alignment film according to claim 1. 3. A surface of the liquid crystal holding substrate on which electrodes are formed,
After applying the composition for liquid crystal alignment film according to claim 1 or 2,
A method for producing a liquid crystal alignment film, which comprises drying, dehydrating and ring-closing to form a polyimide layer and then rubbing. 4. A liquid crystal alignment film formed from the liquid crystal alignment film composition according to claim 1. 5. A liquid crystal holding substrate having the liquid crystal alignment film according to claim 3. 6. A liquid crystal display in which an electrode is 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 a liquid crystal alignment film according to claim 1 is formed on the substrate and the electrode. element.