JPH10274772A - Composition for liquid crystal orienting film, production of liquid crystal orienting film, liquid crystal orienting film, liquid crystal holding substrate and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a compsn. for a liq. crystal orienting film excellent in printability at the time of film formation and free from unevenness in film thickness by using a solvent contg. a specified amt. of a ketone solvent. SOLUTION: A solvent contg. >=10 wt.% ketone solvent is used as the solvent of a compsn. for a liq. crystal orienting film. Since most of a liq. crystal orienting film forming resin in the compsn. is insoluble in the ketone solvent, the ketone solvent is used by <=60 wt.% of the total amt. so as to prevent the deposition of the resin. In order to satisfactorily reduce surface tension, a satd. aliphatic or alicyclic ketone compd. is used as the ketone solvent. The liq. crystal orienting film forming resin is, e.g. polyimide resin, its precursor, polyamide imide resin, its precursor or polyamide resin. The resultant compsn. for a liq. crystal orienting film is applied on the surfaces of liq. crystal holding substrates with formed electrodes, drying and dehydration ring closure are carried out to form layers of the resin and the layers are rubbed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a composition for a liquid crystal alignment film, a method for producing a liquid crystal alignment film, a liquid crystal alignment film, a liquid crystal sandwiching substrate, and a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, trimethyl-2-pyrrolidone (Japanese Patent Application Laid-Open No.
JP-A-1-177440), γ-butyrolactone (see JP-A-1-295226, etc.) and 2-butoxyethanol (butyl cellosolve) (see JP-A-6-349).
No. 79) is generally used. Particularly, 2-butoxyethanol is used to ensure good printability.

In general, a printing method is used for forming an alignment film. In order to improve wettability during printing and to prevent repelling and contraction of a liquid after printing as the size of the liquid crystal display element becomes smaller. A solvent having a low surface tension is added to ensure good printability. As the solvent having a low surface tension, N-methyl-2 which is a solvent used in the composition for a liquid crystal alignment film is used.
The surface tension is lower than that of pyrrolidone (surface tension 41 dyn / cm) or γ-butyrolactone (surface tension 43.9 dyn / cm);
2-butoxyethanol (surface tension 27.4 dyn / cm) compatible with these solvents is generally used.

However, with the recent high quality of liquid crystal display devices, unevenness in film thickness during printing has influenced display characteristics, and it has become necessary to ensure good printability. ing. Since 2-butoxyethanol, which is usually used for ensuring good printability, has an alcohol terminal, it decomposes polyimide or polyamide used in the composition for liquid crystal alignment film by solvolysis and causes a decrease in viscosity. It was necessary to store frozen at a low temperature of 5 ° C. or less. In addition, since the liquid crystal alignment film is used at room temperature during printing, the viscosity may decrease during use. Therefore, the liquid crystal alignment film composition may be continuously left at room temperature for 24 hours or more. could not. Therefore, in order to ensure good printability, it is necessary to control the viscosity of the liquid crystal alignment film composition and frequently finely adjust the conditions of the liquid crystal alignment film printing machine depending on the viscosity.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, and hardly causes a change in viscosity. Therefore, the present invention provides a composition and a film for a liquid crystal alignment film, which have excellent printability during film formation and have no unevenness in film thickness. A method for producing a liquid crystal alignment film having no thickness unevenness, a liquid crystal alignment film having no thickness unevenness obtained from this composition, a liquid crystal sandwiching substrate having the liquid crystal alignment film having no thickness unevenness, and a liquid crystal display element It is.

[0006]

Means for Solving the Problems The present invention provides a composition for a liquid crystal alignment film containing a resin for forming a liquid crystal alignment film and a solvent,
The present invention relates to a composition for a liquid crystal alignment film in which a solvent contains a ketone-based solvent in an amount of 10 to 60% by weight. Further, the present invention provides the composition for a liquid crystal alignment film, wherein the liquid crystal alignment film-forming resin is a resin selected from the group consisting of a polyimide resin, a polyamideimide resin, a precursor thereof, and a polyamide resin. Composition. Further, the present invention, on the surface of the liquid crystal sandwich substrate on which the electrodes are formed, after applying any of these liquid crystal alignment film composition, dried, dehydration ring closure to form a liquid crystal alignment film forming resin layer, Next, the present invention relates to a method for producing a liquid crystal alignment film, characterized by rubbing.
Further, the present invention relates to a liquid crystal alignment film formed by the method of manufacturing the liquid crystal alignment film. The present invention also relates to a liquid crystal sandwich substrate having the liquid crystal alignment film. Further, according to the present invention, an electrode is provided on the liquid crystal sandwiching substrate on the side facing the liquid crystal, and a liquid crystal alignment film obtained from any of the liquid crystal alignment film compositions is formed on the substrate and the electrode. Liquid crystal display device.

The composition for a liquid crystal alignment film in the present invention is intended to improve its printability. For this purpose, a ketone-based solvent is used as a solvent in the composition in an amount of 10% by weight or more based on the total amount of the solvent. use. Thereby, the surface tension can be sufficiently reduced, and the printability can be improved. Most of the liquid crystal alignment film-forming resin in the composition for a liquid crystal alignment film is insoluble in a ketone-based solvent, so that the precipitation of the liquid crystal alignment film-forming resin is prevented. It is preferred to use. In order to sufficiently lower the surface tension of the composition for a liquid crystal alignment film, a saturated aliphatic or alicyclic ketone compound is preferable as the ketone solvent.

The ketone solvents used in the present invention include 2-pentanone, 3-pentanone, 2-hexanone, methyl isobutyl ketone, 2-heptanone, 4-heptanone, diisobutyl ketone, cyclohexanone,
5 carbon atoms such as octanone, 2-nonanone, 3-heptanone, diisopropyl ketone, methyl isobutyl ketone
~ 9 ketone compounds are preferred. These may be used in combination of two or more.

As the other solvent, a solvent which dissolves a resin for forming a liquid crystal alignment film is preferable. For example, N-methyl-2-pyrrolidone, N, N-dimethylformamide,
One or more polar solvents such as N, N-dimethylacetamide, dimethylsulfoxide, tetramethylsulfone, and 1,4-dioxane are used.

As the liquid crystal alignment film forming resin, polyimide resin, polyamide imide resin, precursors thereof, polyamide resin and the like are used.

The polyimide resin and its precursor are not particularly limited as long as they are obtained by reacting a diamine compound and a tetracarboxylic dianhydride in a solvent. It is preferable that the diamine compound and the tetracarboxylic dianhydride are reacted in substantially equimolar amounts.

Examples of the diamine compound include 1,4-diaminobenzene, 1,3-diaminobenzene, 1,2-diaminobenzene, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, and 3,3 '.
-Diaminodiphenyl ether, 1,4-diamino-
2,3,5,6-tetramethylbenzene, 2,2-bis (4- (4-aminophenoxy) phenyl) propane,
2,2-bis (4- (4-aminophenoxy) phenyl) -1,1,1,3,3,3-hexafluoropropane, 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 1,8 -Diaminooctane, 1,6
-Diaminohexane and the like, and these can be used in combination of two or more.

As the diamine, diaminosilicon is represented by the following general formula (I)

Embedded image (Wherein, R ¹ and R ² represent a phenylene group which may have an alkyl group having 1 to 3 carbon atoms as a substituent,
Represents a divalent hydrocarbon group such as an alkylene group, which may be the same or different, and R ³ and R ⁴ have 1 to 1 carbon atoms.
A monovalent hydrocarbon group such as a phenyl group which may have 3 alkyl groups as a substituent or an alkyl group having 1 to 5 carbon atoms, which may be the same or different, and m is 1
May be used. Diaminosilicon is preferably from 0 to 80% by weight, particularly preferably from 0 to 5% by weight, based on the total amount of the diamine compound.
0% by weight is used.

The tetracarboxylic dianhydrides include pyromellitic dianhydride, methyl pyromellitic dianhydride, dimethyl pyromellitic dianhydride, di (triple-olomethyl) hiromellitic dianhydride, 3,3 ',
4,4'-biphenyltetracarboxylic dianhydride, 5,
5'-dimethyl-3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, p- (3,4-dicarboxydiphenyl) benzenene dianhydride, 3,3', 4,4'-tetracarboxy Diphenyl ether dianhydride, 2,3
3 ', 4'-tetracarboxydiphenyl ether dianhydride, 3,3', 4,4'-tetracarboxybenzophenone dianhydride, 1,4,5,7-tetracarboxynaphthalene dianhydride, 1,2,5 2,6-tetracarboxynaphthalene dianhydride, 3,3 ', 4,4'-tetracarboxydiphenylmethane dianhydride, 2,2-bis (3,
4-dicarboxyphenyl) propane dianhydride, 2,2
-Bis (3,4-dicarboxidiphenyl) -1,1,
1,3,3,3-hexafluoropropane dianhydride,
3,3 ', 4,4'-tetracarboxydiphenylsulfone dianhydride, 3,4,9,10-tetracarboxyberylene dianhydride, 3,3', 4,4'-ethylene glycol bis (phenyl) Tetracarboxylic dianhydride, 1,
2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclophthalanetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride and the like can be mentioned. 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, dimethylsulfoxide, tetramethylsulfone, 1,4-dioxane and the like are used. In addition to these solvents, a solvent for improving coatability on a glass substrate can be added before or after the reaction. As these solvents, for example, butyl cellosolve, butyl cellososolve acetate, xylene, toluene and the like are used.

The reaction is preferably carried out at 80 ° C. or lower, particularly preferably at 0 to 50 ° C. This produces polyamic acid. The polyamic acid may be partially imidized, and these are collectively referred to as a polyimide resin precursor. Therefore, the reaction temperature is 250 ° C.
Temperature may be increased. The polyimide precursor is preferable because it is soluble in the solvent of the composition for a liquid crystal alignment film. This precursor is preferably completely imidized to form a polyimide resin when a liquid crystal alignment film forming resin layer is formed on the substrate. The polyimide resin precursor can be imidized in advance if it is soluble in the solvent of the composition for a liquid crystal alignment film. For imidization, the above reaction is carried out in 12
There are thermal imidization performed at 0 to 250 ° C. and chemical imidization performed in the presence of a dehydrating agent. As the dehydrating agent, acid anhydrides such as acetic anhydride, propionic anhydride and benzoic anhydride, carbodiimide compounds such as dicyclohexylcarbodiimide and the like are preferable, and 1 to 8 mol is used per 1 mol of tetracarboxylic dianhydride. preferable. At this time, pyridine, isoquinoline, trimethylamine, aminopyridine, imidazole and the like can be used as a dehydration catalyst as required. The dehydration catalyst is preferably used in an amount of 1 to 8 mol per 1 mol of tetracarboxylic dianhydride.

As the polyamide-imide resin and its precursor, those produced in the same manner as the above-mentioned polyimide resin and its precursor can be used. However, instead of tetracarboxylic dianhydride, trimellitic anhydride or a derivative such as chloride of trimellitic anhydride is used. Further, in the above method for producing a polyamideimide and a precursor thereof, a diisocyanate compound may be used instead of the diamine compound to produce the same. Further, similarly to the above, after these reactions, the resin is separated, and may be again dissolved in an organic solvent to obtain the composition for a liquid crystal alignment film in the present invention. By adding, it can be used as the composition for a liquid crystal alignment film in the present invention.

As the polyamide resin, those produced in the same manner as the above-mentioned polyimide resin and its precursor can be used. However, instead of tetracarboxylic dianhydride, terephthalic acid, isophthalic acid, a divalent aromatic dicarboxylic acid of phthalic acid, or a derivative thereof such as dichloride is used. Further, similarly to the above, after these reactions, the resin is separated, and may be again dissolved in an organic solvent to obtain the composition for a liquid crystal alignment film in the present invention. By adding, it can be used as the composition for a liquid crystal alignment film in the present invention.

In addition, a phenol resin can be used as the liquid crystal alignment film forming resin. The phenolic resin is obtained by reacting a phenol such as an alkylphenol having an alkyl group such as phenol, butyl group, and octyl group with an aldehyde compound such as formaldehyde. There are no restrictions. Either a novolak phenol resin or a resol phenol resin may be used as the phenol resin. Further, a novolak type phenol resin, particularly a novolak type phenol resin having an alkyl side chain, is preferable from the viewpoint of compatibility with the polyamic acid. These phenolic resins are 1
They can be used alone or in combination of two or more. The phenol resin is preferably used in combination with the above-mentioned polyimide, polyamide imide, a precursor thereof or a polyamide resin, and is used in an amount of 5 to 70% by weight based on the weight of the resin. By using the phenol resin, it is possible to eliminate the need for the flattening treatment of the base of the liquid crystal alignment film, which is considered to be necessary for ensuring display uniformity.

The composition for a liquid crystal alignment film has a viscosity of 1 when used.
It is preferable that the pressure be 0 mPa · s to 200 mPa · s (25 ° C.). The viscosity can be adjusted by appropriately selecting the concentration and the solvent according to the liquid crystal alignment film forming resin.

After printing the composition for a liquid crystal alignment film of the present invention on a substrate, the composition is heated to 100 to 400 ° C. to form a resin layer. Provide an electrode on the liquid crystal sandwiching substrate on the side facing the liquid crystal,
A liquid crystal alignment film obtained from a liquid crystal alignment film composition is formed on the substrate and the electrodes to obtain a liquid crystal display device.

The liquid crystal alignment film of the present invention is formed on a liquid crystal substrate by applying the above-mentioned composition for a liquid crystal alignment film to, for example, ITO (Individual).
um Tin Oxide) is printed on a glass substrate on which a transparent electrode is formed, and then heated to form a resin layer. Heating temperature is 100-400 ° C, preferably 150-
It can be arbitrarily selected in the range of 300 ° C. The heating time is 1 minute to 6 hours, preferably 1 minute to 3 hours.

The resin 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.

[0024]

The present invention will be described below with reference to examples. Example 1 4.0 g of 4,4'-diaminodiphenylmethane (0.0 g)
2 mol) and 13.1 g (0.08 mol) of 1,4-diamino-2,3,5,6-tetramethylbenzene were added with 221 g of N-methyl-2-pyrrolidone, and the mixture was stirred sufficiently. 21.8 g (0.10 mol) of acid dianhydride was added and reacted at 20 ° C. for 8 hours to obtain a pale yellow viscous polyimide resin solution. N-methyl-2 was added to this solution.
-259.4 g of pyrrolidone and 25 of diisobutyl ketone
8.7 g was added and diisobutyl ketone was added at 35% by weight of the solvent.
A composition for a liquid crystal alignment film having a resin content of 5% by weight and a viscosity of 30 mPa · s was prepared. This composition for a liquid crystal alignment film is printed on two glass substrates on which ITO transparent electrodes are formed so as to form 640 × 200 dots, and heated at 250 ° C. for 30 minutes to remove the solvent and dehydrate the polyamic acid for dehydration and ring closure. Do
A 60 nm polyimide layer was formed. A rubbing process is performed on the surface of the polyimide layer on these two glass substrates to obtain a liquid crystal sandwiching substrate as a liquid crystal alignment film, and the two polyimide layers are combined such that the rubbing directions are anti-parallel, Surrounding epoxy sealant EN-10
00 (Hitachi Kasei Kogyo Co., Ltd.), assemble the cell, and use the chiral agent C so that it becomes a 240 degree twist.
Liquid crystal ZLI- added with B-15 (trade name, manufactured by Merck)
2293 (trade name, manufactured by Merck) was sealed to prepare an STN-type liquid crystal display device. The liquid crystal display element showed good alignment without unevenness by visual lighting observation. After leaving the composition for a liquid crystal alignment film of the present invention at 25 ° C. for 1 day, a polyimide layer was formed by the method described above, but no unevenness in the thickness of the polyimide layer was observed. In addition, an STN-type liquid crystal display device was prepared in the same manner, and the liquid crystal display device showed good alignment without unevenness by visual observation. When the composition for a liquid crystal alignment film used in this example was stored in a refrigerator at 7 ° C., the viscosity was 30 mPA · s even after 6 months.

Comparative Example 1 259.4 g of N-methyl-2-pyrrolidone and 258.2-butoxyethanol were added to the polyimide resin solution of Example 1.
7 g was added, and 2-butoxyethanol was added at 35% by weight of the solvent.
A composition for a liquid crystal alignment film having a resin content concentration of 5% by weight and a viscosity of 30 mPA · s was prepared. Using this composition for a liquid crystal alignment film, a polyimide layer was formed in the same manner as in Example 1, but no unevenness in the thickness of the polyimide layer was observed. Also,
The STN-type liquid crystal display element produced by the same method showed good alignment without unevenness by visual lighting observation. After the liquid crystal alignment film composition was left at 25 ° C. for 1 day, a polyimide layer was formed by the above-described method. Unevenness was seen. In addition, an STN-type liquid crystal display device was prepared in the same manner, but the liquid crystal display device was found to be uneven by visual observation. In addition, the composition for a liquid crystal alignment film used in
When stored in a refrigerator at ℃, the viscosity after one month was 23 mPA
s had dropped.

[0026]

When a liquid crystal alignment film is formed from the composition for a liquid crystal alignment film of the present invention and a liquid crystal display device is produced using a liquid crystal display substrate having the liquid crystal alignment film, printability and workability are good. And, since it is possible to obtain a liquid crystal display device of good display quality, the composition for a liquid crystal alignment film of the present invention,
It is preferably used for a liquid crystal display element of high display quality. The composition for a liquid crystal alignment film according to claims 1 and 2 has good printability and workability, and further has excellent storage stability. Accordingly, it is possible to form a liquid crystal alignment film having excellent liquid crystal alignment without a thickness unevenness. By the method in claim 3, therefore:
A liquid crystal alignment film having excellent properties can be formed. Claim 4
The liquid crystal alignment film of No. 3 has no thickness unevenness and is excellent in liquid crystal alignment. The liquid crystal sandwiching substrate according to claim 5 has a liquid crystal alignment film having no unevenness in film thickness, and thus has a good liquid crystal alignment property. Since the liquid crystal display element according to claim 6 has the liquid crystal alignment film without unevenness in film thickness, the liquid crystal alignment is good.

Claims (6)

[Claims] A liquid crystal alignment film composition comprising a liquid crystal alignment film forming resin and a solvent, wherein the solvent is a ketone-based solvent.
A composition for a liquid crystal alignment film, which comprises about 60% by weight. 2. The liquid crystal alignment film-forming resin is a resin selected from the group consisting of a polyimide resin, a polyamide-imide resin, a precursor thereof, and a polyamide resin.
The composition for a liquid crystal alignment film according to the above. 3. A liquid crystal sandwiching substrate on 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 or 2, followed by drying to form a layer of a resin for forming a liquid crystal alignment film, and then rubbing. 4. A liquid crystal alignment film formed by the method according to claim 3. 5. A liquid crystal sandwiching substrate having the liquid crystal alignment film according to claim 4. 6. A liquid crystal sandwiching substrate according to claim 5, wherein an electrode is provided on the side facing the liquid crystal, and the electrode is provided on the substrate and the electrode.
Or a liquid crystal display element formed with a liquid crystal alignment film obtained from the composition for a liquid crystal alignment film according to 2.