JP3095100B2 - Liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device. And a liquid crystal display device having excellent reliability.

[0002]

2. Description of the Related Art Conventionally, the material constituting a cell into which a liquid crystal is injected in a liquid crystal display device includes upper and lower substrates with transparent electrodes, a liquid crystal alignment film formed thereon, sealing materials and sealing materials surrounding the periphery, And a spacer for taking a cell gap. In recent years, a film called a flattening film or an insulating film is formed between a substrate with a transparent electrode and a liquid crystal alignment film in order to improve reliability and display quality, particularly to improve in-plane display uniformity. Things are going on. However, since these coatings are inorganic materials such as silica, 350-400
A high temperature process of ° C. is required. For this reason, the cost is increased, and furthermore, when the substrate is a plastic film, these coatings cannot be formed, and there is a problem that only those having a display quality inferior to a liquid crystal display element of a glass substrate can be manufactured.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the liquid crystal display element and can easily form a good film in an insulating film forming step in a liquid crystal display element manufacturing process. Another object of the present invention is to provide a liquid crystal display device having high display quality and excellent reliability.

[0004]

The silicone-modified polyimide film between the substrate with a transparent electrode and the alignment film in the present invention serves as a conventional insulating film and a flattening film, and is further formed at 120 to 200 ° C. Is possible. For this reason, it is possible to reduce the cost of the process of the conventional glass substrate liquid crystal, and it is possible to form a film even when the substrate is a plastic film.

[0005] The silicone-modified polyimide film in the present invention is formed by applying a solution of a silicone-modified polyimide precursor or a solution of a soluble silicone-modified polyimide by printing, spin coating, or the like, at 120 to 200 ° C, more preferably 150 to 200 ° C.
It can be obtained by forming a film at 00 ° C. If the temperature is lower than 120 ° C., it is difficult to completely remove the solvent, which is not preferable.

The silicone-modified polyimide precursor solution or the soluble silicone-modified polyimide solution used in the present invention comprises a diamine having silicone in its structure, an aromatic or aliphatic dianhydride, and an aromatic or aliphatic diamine in a polar solvent. In the reaction.

Preferred examples of the diamine having a silicone in its structure include 1,3-bis (aminopropyl) tetramethyldisiloxane and the diaminosilicone compound represented by the formula (1), but are not limited thereto. Not something.

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Preferred examples of the aromatic or aliphatic acid dianhydride include 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 3,3', 4,4'-benzophenone Tetracarboxylic dianhydride, 3,3'-oxydiphthalic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 3,3 ', 4,4'-diphenyl Sulfonetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 5- (2,5-dioxo Tetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, bicyclo [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic acid It is anhydrous, but is not limited to these.

Preferred examples of the aromatic or aliphatic diamine include p-phenylenediamine, m-phenylenediamine, 2,5-diamino-p-xylene, 3,3'-dimethylbenzidine, 2,2- Bis (trifluoromethyl) benzidine, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 2,2-bis [4,
4 '-(4-aminophenoxy) phenyl] propane, 2,2-bis
[4,4 '-(4-aminophenoxy) phenyl] hexafluoropropane, 1,4-diaminocyclohexane, 1,3-bis (aminomethyl) cyclohexane, 4,4'-diaminodicyclohexylmethane, etc. However, the present invention is not limited to this.

Examples of preferred polar solvents include N-methyl-2-pyrrolidone, dimethylformamide,
Dimethylacetamide, m-cresol, γ-butyrolactone, and the like, but are not limited thereto.

The silicone-modified polyimide film of the present invention comprises:
As described above, it is more effective when the substrate is made of plastic. Preferred examples of the plastic film serving as the substrate in the present invention include, but are not limited to, polyethylene terephthalate, polyethersulfone, and polyarylate.

[0012]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 17.45 g (0.08 mol) of pyromellitic dianhydride was placed in a four-neck separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube.
Disperse in 200 g of methyl-2-pyrrolidone. A diaminosilicone compound represented by the formula (1)
10.90 g (0.02 mol) was added dropwise.
The reaction was carried out while maintaining the temperature. Subsequently, 24.63 g (0.06 mol) of 2,2-bis (4- (4-aminophenoxy) phenyl) propane was charged at once, and stirring was continued for 5 hours while maintaining the temperature at 20 ° C. to obtain a silicone-modified polyamic acid solution. .

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This silicone-modified polyamic acid solution is diluted with γ-butyrolactone so that the resin concentration becomes 5%, and the line width is 900 μm and the pitch is 1000 μm using a flexographic printing machine.
It is printed on a 60 mm × 60 mm polyethersulfone film substrate on which a μm ITO electrode pattern is formed and
Heating was performed at 0 ° C. for 1 hour to form a silicone-modified polyimide film on the substrate.

A liquid crystal aligning agent (Sumitomo Bakelite) is formed on the silicone-modified polyimide film by using a flexographic printing machine.
(Sumiresin Excel CRD-4009, manufactured by Co., Ltd.) was printed and heated in a dryer at 150 ° C. for 2 hours to form a liquid crystal alignment film. An STN cell having a cell gap of 7 μm was prepared by the usual method using two substrates on which the above-mentioned coatings were formed. The liquid crystal used was "ZLI-2293" manufactured by Merck.

When a rectangular wave of ± 5 V and 33 Hz was applied between the upper and lower ITO patterns of the obtained liquid crystal display element, good display without unevenness was obtained over the entire surface. When this liquid crystal display element was left in a constant temperature bath at 85 ° C. for 168 hours, returned to room temperature, and then applied with the same waveform, good display without unevenness was obtained over the entire surface.

(Examples 2 and 3 and Comparative Examples 1 and 2)
As shown in (1), a liquid crystal display element was manufactured in the same manner as in Example 1 except that the substrate material, the insulating film material, and the insulating film forming conditions were changed, and the display unevenness was evaluated.

[0018]

[Table 1] 1) PET; polyethylene terephthalate 2) Silicone-modified polyimide solution; Sumitomo Bakelite
Sumirejin Excel CRC-7040 manufactured by 3) PA; polyarylate 4) PES; polyether sulfone

In Examples 1 to 3, the liquid crystal display devices had good display quality without unevenness immediately after fabrication and after standing at 85 ° C. for 168 hours. In Comparative Example 1, since the silica-based coating agent was used, the insulating film forming temperature had to be as high as 300 ° C. For this reason, although PES was used as a plastic with relatively high heat resistance, the substrate deteriorated, and a liquid crystal display element could not be manufactured. In Comparative Example 2,
Since there was no silicone-modified polyimide film between the substrate with the transparent electrode and the liquid crystal alignment film, the display immediately after the preparation was good, but unevenness occurred in the entire surface after standing at 85 ° C for 168 hours. .

[0020]

According to the liquid crystal display device of the present invention, a good film can be easily formed in the insulating film forming step in the process of manufacturing the liquid crystal display device, and the display quality is high and the reliability is excellent. It is.

Claims (2)

(57) [Claims] 1. A liquid crystal display device comprising a silicone-modified polyimide film between a substrate with a transparent electrode constituting a liquid crystal cell and a liquid crystal alignment film. 2. The liquid crystal display device according to claim 1, wherein the substrate is a plastic film.