JPH075472A - Production of liquid crystal oriented film composition therefor liquid crystal holding substrate, liquid crystal oriented film, and liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide a compsn. for a liquid crystal oriented film to form a liquid crystal oriented film having a pretilt angle >=3 deg. suitable for an active matrix-type liquid crystal display element. CONSTITUTION:(1) This compsn. for a liquid crystal oriented film contains a polyimide soln. and tetracarboxylic acid expressed by formula. The polyimide soln. contains polyimide obtd. by imidization of polyamide acid obtd. by the reaction of diamine compd. and tetracarboxylic acid dianhydride in a solvent In the formula, R is a quadrivalent hydrocarbon group or hydrocarbon group containing silicon and/or siloxane bond. This compsn. is used to form a liquid crystal oriented film of this invention.

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, there is known an active matrix type liquid crystal display element in which an active element (TFT type or MIM type) for switching is provided for each pixel of the liquid crystal display element. A polyimide-based alignment film is used for the display element, and the twist angle of liquid crystal molecules in the element is 90 °.
TN type is used. However, since the conventional polyimide-based alignment film has an angle (pretilt angle) between liquid crystal molecules and the alignment film of less than 3 °, it may cause a reverse tilt phenomenon when the liquid crystal display element is driven, resulting in display failure. The display failure is likely to occur particularly at the stepped portion on the active element, and the pretilt angle is set to 3 to prevent this.
There is a demand for a material for an alignment film having a temperature of at least °.

[0003]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, a composition for a liquid crystal alignment film capable of setting a pretilt angle of 3 ° or more, 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 are provided.

[0004]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies in view of the above-mentioned problems of the prior art, and as a result, formed a liquid crystal alignment film using a composition containing tetracarboxylic acid in a polyimide solution. Then, they found that the pretilt angle was 3 ° or more, and reached the present invention. That is, the present invention is
(1) A polyimide solution containing a polyimide imidized with a polyamic acid obtained by reacting a diamine compound and a tetracarboxylic dianhydride in a solvent, and (2) the general formula (I).

[Chemical 5] (In the formula, R is a tetravalent hydrocarbon group or silicon and / or
Or a liquid crystal alignment film containing a tetracarboxylic acid represented by (meaning a hydrocarbon group containing a siloxane bond), a method for producing a liquid crystal alignment film using this composition, and a composition formed from this composition The present invention relates to a liquid crystal alignment film, a liquid crystal holding substrate on which the liquid crystal alignment film is formed, and a liquid crystal display element having the liquid crystal holding substrate.

The tetracarboxylic acid represented by the general formula (I) used in the present invention includes pyromellitic acid,
3,3 ', 4,4'-diphenyltetracarboxylic acid,
3,3 ', 4,4'-dicyclohexyltetracarboxylic acid, 1,3-bis (3,4-dicarboxyphenyl)-
1,1,3,3-tetramethyldisiloxane, bis (3,4-dicarboxyphenyl) -dimethylsilane,
The tetracarboxylic acid etc. which are represented by the following general formula (II) are mentioned, These can be used individually or in combination of 2 or more types.

General formula (II)

[Chemical 6] (In the formula, Ar ₁ and Ar ₂ are aromatic groups, R ₁ , R ₂ and R ₃
And R ₄ is an alkyl group having 1 to 10 carbon atoms, and 1 to 1 carbon atoms.
10 substituted alkyl groups or substituted or unsubstituted aromatic groups, X ₁ and X ₂ are

[Chemical 7]

[Chemical 8] (N is an integer of 1 to 10), and a and c are 0.
Alternatively, 1 or b is 0 or an integer of 1 to 5) is preferably used.

The tetracarboxylic acid represented by the general formula (II) is 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3-tetramethyldisiloxane, 1,3 -Bis (3,4-dicarboxyphenyl)-
1,1,3,3-tetraethyldisiloxane, 1,3-
Bis (3,4-dicarboxyphenyl) -1,1,3
3-tetraphenyldisiloxane, 1,3-bis {3-
(3,4-dicarboxybenzoyloxy) propyl}
-1,1,3,3-tetramethyldisiloxane, 1,3
-Bis {2- (3,4-dicarboxybenzoyloxy) ethyl} -1,1,3,3-tetramethyldisiloxane, 1,3-bis {5- (3,4-dicarboxybenzoyloxy) pentyl } -1,1,3,3-Tetramethyldisiloxane, 1,3-bis {3- (3,4-dicarboxybenzoyloxy) propyl} -1,1,3
3-tetraphenyldisiloxane, bis (3,4-dicarboxybenzoyloxy) diphenylsilane, bis (3,4-dicarboxybenzoyloxy) dimethylsilane, bis (3,4-dicarboxybenzoyloxy)
Ethylmethylsilane, 1,3-bis (3,4-dicarboxyphenyl) -1,3-dimethyl-1,3-diethyldisiloxysan, 1,3-bis (3,4-dicarboxyphenyl) -1 , 1,3,3,5,5-hexamethyltrisiloxane, 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3,5,5,7,7-octamethyltetra Siloxane, 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3,5,5,7,7,
9,9-decamethylpentasiloxane, 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3,
5,5,7,7,9,9,11,11-dodecamethylhexasiloxane and the like can be mentioned, and these can be used alone or in combination of two or more kinds.

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

Examples of the diamine compound include m-phenylenediamine, p-phenylenediamine and 4,4'-
Diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3 ', 5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 2,2 -Bis (4-aminophenyl) propane, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,2-bis (4- Aminophenoxyphenyl) propane, 2,2-bis (4-aminophenoxyphenyl) -1,1,1,3,3,3-hexafluoropropane, 1,3-bisaminopropyl-1,
1,3,3-tetramethyldisiloxane, bis (4-
(3-Aminophenoxy) phenyl) sulfone, 1,3
-Diamino-2,3,5,6-tetramethylbenzene 9,9-bis (4-aminophenyl) fluorene, 9,
9-bis (4-aminophenyl) anthracene (1
0), 3,3'-diaminodiphenyl sulfone, 4,
4'-diaminodiphenyl ether-3-carbonamide, 1,4-diaminocyclohexane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diamino Decane, 1,11-diaminoundecane, 1,1
2-diaminododecane and the like can be mentioned, and these can be used in combination of two or more kinds.

Examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ', 4,4'-diphenyltetracarboxylic dianhydride, 3,3', 4,4 '.
-Benzophenone tetracarboxylic dianhydride, 2,3
6,7-naphthalenetetracarboxylic dianhydride, 1,
2,5,6-naphthalenetetracarboxylic dianhydride,
2,2 ', 3,3'-diphenyltetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 3 , 3 ', 4,4'-dicyclohexyltetracarboxylic acid dianhydride, bis {exo-bicyclo (2,2,1) heptane-2,3-dicarboxylic acid dianhydride} sulfone, and the like. One or more species can be used in combination.

The organic solvent used for reacting the diamine compound and the tetracarboxylic dianhydride is not particularly limited as long as it dissolves the polyamic acid produced in the reaction, and for example, N-methyl-2-pyrrolidone. , N,
One or more of N-dimethylacetamide, N, N-dimethylformamide, N, N-diethylformamide, dimethyl sulfoxide, hexamethylphosphoramide, tetramethylsulfone, 1,4-dioxane, γ-butyrolactone and the like. Are used in combination.

The polyimide solution used in the present invention is prepared by heating the above polyamic acid or by imidizing it in the presence of a dehydrating agent and an imidizing catalyst. The reaction temperature for imidization by heating is usually 6
It is 0 to 200 ° C, preferably 100 to 170 ° C. In addition, imidization in the presence of a dehydrating agent and an imidization catalyst,
It can be carried out in the above-mentioned organic solvent, and the reaction temperature is usually 0 to 180 ° C, preferably 60 to 150 ° C. As the dehydrating agent, acetic anhydride, propionic anhydride, trifluoroacetic anhydride or the like can be used. As the imidization catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, and triethylamine can be used, but the imidization catalyst is not limited thereto. As the polyimide solution, a polyamic acid solution may be imidized and used as it is, or after the polyamic acid solution is imidized, the polyimide may be separated and dissolved in a solvent to prepare a polyimide solution.

In the composition for liquid crystal alignment film of the present invention, the tetracarboxylic acid represented by the general formula (I), preferably the tetracarboxylic acid represented by the general formula (II) is added to the polyimide solution. And then thoroughly mixed. The tetracarboxylic acid represented by the general formula (I), preferably the tetracarboxylic acid represented by the general formula (II), is added in an amount of 0 relative to polyimide from the viewpoint of film-forming property of the liquid crystal alignment film. It is preferably from 0.05 to 40% by weight, more preferably from 0.5 to 20% by weight.

A solvent for improving the wettability to a glass substrate can be added to the composition for liquid crystal alignment film. As these solvents, for example, butyl cellosolve,
Butyl cellosolve acetate, xylene, toluene and the like are used. Further, a silane coupling agent or the like may be added for the purpose of improving the adhesiveness with the substrate. Examples of the silane coupling agent include γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, δ-aminopropyl methyldiethoxysilane, γ-aminopropyltriethoxysilane and the like.

The composition for liquid crystal alignment film of the present invention can be prepared, for example, by
It is applied by a method such as a dipping method, a printing method or a spraying method on a liquid crystal holding substrate on which a transparent electrode such as ITO (Indium Tin Oxide) is formed in advance, and the temperature is 80 to 230 ° C., preferably 1
It is heated at a temperature of 20 to 200 ° C., dried to form a polyimide layer, and the surface thereof is rubbed to obtain a liquid crystal alignment film. A liquid crystal display device can be obtained by a known method using the liquid crystal holding substrate having this 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 an active matrix type liquid crystal display device.

[0017]

EXAMPLES The present invention will be described below with reference to comparative examples and examples. In addition,% in the examples is% by weight. Example 1 15.770 g (0.038 mol) of 2,2-bis {4- (4-aminophenoxy) phenyl} propane N-
After dissolving in 170 g of methyl-2-pyrrolidone and stirring sufficiently, bis {exo-bicyclo (2,2,1) heptane-2,3-dicarboxylic acid dianhydride} sulfone 14.23
0 g (0.038 mol) was added and reacted at 50 ° C. for 5 hours to synthesize a polyamic acid solution. 84 g of acetic anhydride and 42 g of pyridine were added to the obtained polyamic acid solution, and the mixture was stirred for 2 hours and then left standing at room temperature for 12 hours. The resin was then precipitated in methanol under high shear in a mixer (methanol / polyamic acid solution = 10/1
(Weight ratio), stirring time 2-3 hours). The precipitated resin was recovered and washed with a large amount of methanol by boiling (3 times for 30 minutes). Then, it was dried under reduced pressure at 80 ° C. for 10 hours to obtain a powdery polyimide. 5 g of this polyimide powder was added to N-methyl-
2-pyrrolidone was dissolved in 95 g to prepare a polyimide solution (polyimide solution I) having a total solid content of 5% by weight. To this solution, 1,3-bis (3,4-dicarboxyphenyl)
-1,1,3,3-tetramethyldisiloxane 0.25
g was added and sufficiently stirred to obtain a polyimide solution containing tetracarboxylic acid. This solution was applied onto two glass substrates with transparent ITO electrodes by spinner coating, and the solution was applied at 200 ° C for 1 hour.
It heated for time and the solvent was removed and the polyimide layer was formed. The surface of this layer on two glass substrates is rubbed, and two polyimide layers are made to face each other so that the rubbing direction is antiparallel, and the epoxy sealing agent EN-1000 (Hitachi Chemical Sealed with Kogyo Co., Ltd. product name) and liquid crystal ZLI-4792 inside
(Merc Co., Ltd. product name) was sealed to form a liquid crystal cell.
Next, in order to stabilize this liquid crystal cell, after heating for 1 hour at 120 ° C. which is a temperature above T _NI (95 ° C.) of liquid crystal ZLI-4792 as an aging treatment, the pretilt angle was measured using laser light. The corner is 3.2
And satisfied the requirements for an alignment film for an active matrix type liquid crystal display device.

Example 2 The polyimide solution I used in Example 1 was mixed with 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3-
0.75 g of tetramethyldisiloxane was added, and the mixture was stirred for half to obtain a polyimide solution containing tetracarboxylic acid. Using this solution, a liquid crystal cell was formed in the same manner as in Example 1 and the pretilt angle was measured. As a result, the pretilt angle was 4.0 °, which satisfied the requirements of the active matrix type alignment film for a liquid crystal display element. Was there.

Example 3 The polyimide solution I used in Example 1 was mixed with 1,3-bis (3,4-dicarboxyphenyl) -1,1,3,3-
Tetramethyldisiloxane (1.25 g) was added, and the mixture was thoroughly stirred to obtain a polyimide solution containing tetracarboxylic acid. Using this solution, a liquid crystal cell was formed in the same manner as in Example 1 and the pretilt angle was measured. As a result, the pretilt angle was 4.2 °, which satisfied the necessary conditions for the alignment film for an active matrix type liquid crystal display device. Was there.

Comparative Example 1 Using the polyimide solution I used in Example 1, Example 1
When a liquid crystal cell was formed by the same method as described above and the pretilt angle was measured, the pretilt angle was 2.5 °, which did not satisfy the requirements for the alignment film for an active matrix type liquid crystal display device.

[0021]

According to the composition for liquid crystal alignment film of the present invention,
A liquid crystal alignment film having a pretilt angle of 3 ° or more can be formed. Further, since this liquid crystal alignment film can be formed at a temperature of 200 ° C. or lower, it can be suitably used especially for an active matrix liquid crystal display device.

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

Claims (7)

[Claims] 1. A polyimide solution containing (1) a polyimide imidized with a polyamic acid obtained by reacting a diamine compound and a tetracarboxylic dianhydride in a solvent, and (2) a compound represented by the general formula (I): ] (In the formula, R is a tetravalent hydrocarbon group or silicon and / or
Or a tetracarboxylic acid represented by a hydrocarbon group having a siloxane bond). 2. A tetracarboxylic acid is represented by the general formula (II): (In the formula, Ar ₁ and Ar ₂ are aromatic groups, R ₁ , R ₂ and R ₃
And R ₄ is an alkyl group having 1 to 10 carbon atoms, and 1 to 1 carbon atoms.
10 substituted alkyl groups or substituted or unsubstituted aromatic groups, X ₁ and X ₂ are [Chemical 4] (N is an integer of 1 to 10), and a and c are 0.
Alternatively, 1, b is a tetracarboxylic acid represented by 0 or an integer of 1 to 5), The composition for liquid crystal alignment film according to claim 1. 3. The tetracarboxylic acid represented by the general formula (I) or the tetracarboxylic acid represented by the general formula (II) is contained in an amount of 0.05 to 40% by weight based on the polyimide. The composition for liquid crystal alignment film of. 4. The composition for liquid crystal alignment film according to claim 1, 2 or 3 is applied and dried on a surface of a liquid crystal holding substrate on which an electrode is formed to form a polyimide layer, and then the surface of the polyimide layer. Of rubbing liquid crystal alignment film. 5. A liquid crystal alignment film formed from the composition for liquid crystal alignment film according to claim 1. 6. A liquid crystal holding substrate having a liquid crystal alignment film formed from the composition for liquid crystal alignment film according to claim 1. 7. 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.