JPH05249473A - Oriented film and liquid crystal display body - Google Patents

Abstract

(57) [Abstract] [Purpose] Improvement of crosstalk in STN and NTN liquid crystal displays and development of new alignment films. [Structure] An alignment film containing nitrogen (excluding imide-bonded nitrogen) in its skeleton is used instead of the conventional alignment film. [Effect] The frequency characteristic becomes almost flat.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel liquid crystal alignment film and a liquid crystal display.

[0002]

2. Description of the Related Art A liquid crystal alignment film is applied to a surface of a liquid crystal cell of a liquid crystal display body of which a liquid crystal display is opposed to a surface in contact with liquid crystal and is rubbed to regulate the alignment direction of the liquid crystal. Is responsible for improving the display quality of. In FIG. 1, 1 is a glass substrate, 2 is a transparent electrode, 3 is an alignment film, 4 is a spacer, 5 is a liquid crystal, 6 is a compensation plate, and 7 is a polarizing plate. Heretofore, a polyimide-based polymer composed of tetracarboxylic sun anhydride and a diamino compound has been used as the liquid crystal alignment film. The characteristic of this polyimide compound was that the nitrogen atom was only the atom of the imide group and was not contained in other atoms.

[0003]

However, when the conventional alignment film is used, the transmittance of the liquid crystal display differs depending on the frequency. For this reason, in a display body in which different frequencies are overlapped due to driving, there is a drawback in that the transmittance is partially different, that is, so-called crosstalk occurs, and the display quality is degraded. The development of an alignment film that solves this drawback is an important issue in the field of liquid crystal displays.

[0004]

The present invention has been made to solve the above problems, and it has been solved by using a novel alignment film having the following features. The alignment film of the present invention is basically a polyimide containing nitrogen other than the nitrogen of the imide group in the basic skeleton. The polyimide-based alignment film of the present invention is obtained by copolymerizing a normal tetracarboxylic acid dianhydride containing no nitrogen with a diamino compound having nitrogen in addition to the amino group, or a tetracarboxylic acid dianhydride containing nitrogen and other than the amino group. Can be obtained by copolymerizing a nitrogen-free diamino compound or by copolymerizing a nitrogen-containing tetracarboxylic acid dianhydride with a nitrogen-containing diamino compound other than an amino group. Examples of the nitrogen-free tetracarboxylic acid dianhydride, which is a raw material of the polyimide-based polymer of the present invention, include pyromellitic dianhydride, 3, 3 ′, 4,
4'-biphenyl tetracarboxylic acid dianhydride, 1,
2,3,4-cyclobutanetetracarboxylic dianhydride,
2,3,5-Tricarbonyloxypentyl acetic acid dianhydride, 3,3 ', 4,4'-benzophenone tetracarboxylic acid dianhydride, 1,4,5,8 naphthalene tetracarboxylic acid dianhydride, ethylene Glycol bis (anhydrotrimellitate), 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride, 3,4-dicarboxy-1,
2,3,4-Tetrahydronaphthalene-1-succinic dianhydride, etc.
Anhydrides can be used. Further, the nitrogen-containing tetracarboxylic acid dianhydride is 2,3,5,6-benzenetetracarboxylic acid dianhydride, 3,3 ′, 4,4 ′-(2,2′-bipyridyl) tetracarboxylic acid 2 anhydride. Anhydrate or the like is considered. The diamino compound containing nitrogen in addition to the amino group is 3,5-diaminotriazole, 3,6
-Diaminoacridine, 2,6-diaminoacridine,
2,6-diaminophenazine, 2,5-diaminopyridine, 2,3-diaminopyridine, 2,6-diaminopyridine, 3,6-diaminopyridine, 4,6-diaminopyrimidine, 2,4-diamino-S-triazine 3, 5
-Diaminotriazole, etc. can be considered. Examples of diamino compounds containing no nitrogen other than amino groups include 1,4-diaminobenzene, 4,4′-diaminobiphenyl,
4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 2,2-bis (4- (4
-Aminophenoxy) phenyl) propane, bis (4- (4-aminophenoxy) phenyl) sulfone,
4,4'-bis (4-aminophenoxy) biphenyl,
Bis (4- (4-aminophenoxy) phenyl) ether, 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis ( 4-Aminophenoxy) benzene, 4,4'-diaminodiphenyl sulfide and the like can be considered.

By properly combining these compounds, a polyimide compound having nitrogen other than the imide group in the polymer main chain can be obtained.

[0006]

【Example】

(Example 1) Synthesis of Alignment Film 0.0545 g of 2,5-diaminopyridine, 0.098 g of cyclobutanetetracarboxylic dianhydride and 10 millitorr of N-methyl-2-pyrrolidone were placed in a test tube, and the atmosphere was replaced with nitrogen. The reaction was carried out for 5 hours while stirring occasionally.

Preparation and Evaluation of Display Body The polyamic acid solution obtained by the above method was spin-coated (2000 rpm, 20 rpm) on the cell substrate of the liquid crystal display body.
Minute) and then baked at 250 ° C. for 30 minutes in a nitrogen atmosphere to form a polyimide film.

This substrate was rubbed under the following rubbing conditions in the rubbing direction so that the twist angle of the injected liquid crystal was 210 degrees, and then a liquid crystal cell was assembled.

Rubbing conditions 1. Roller radius with nylon brush 6cm 2. Roller rotation speed 800 rpm 3. Substrate moving speed 1 m / min 4. Number of substrate movements 2 times Liquid crystal cell assembled (cell thickness 5.1 micrometer)
A liquid crystal (ss-4062 (manufactured by Chisso Petrochemical Co., Ltd.) adjusted with a chiral liquid crystal S-811 (manufactured by Merck)) was injected and a constant voltage (2v) was applied to the relationship between the transmittance and the frequency. I checked. The obtained results are shown in FIG. For comparison, a commercially available general alignment film sp-74
The characteristics of a liquid crystal cell obtained by using 0 (a Toray product is a copolymer of pyromellitic dianhydride and 4,4′-diaminophenyl ether) under the same conditions are shown in FIG. 1 and 2, the horizontal axis represents frequency (Hz) and the vertical axis represents transmittance.

As can be seen from the figure, the frequency characteristic of the liquid crystal display using the alignment film of the present invention is almost flat, but the liquid crystal display using the conventional alignment film has a large dropout at low frequencies.

Example 2 Synthesis of Alignment Film 3,5-diamino-1,2,4-triazole 0.0
495 grams, cyclobutane tetracarboxylic acid dianhydride 0.098 grams and N-methyl-2-pyrrolidone 10
After taking millitorr in a test tube and replacing with nitrogen, 60 ° C
The reaction was carried out for 5 hours while stirring occasionally.

Preparation and Evaluation of Display Body The polyamic acid solution obtained by the above method was spin-coated (2000 rpm, 20 minutes) on the cell substrate of the liquid crystal display body.
And then baked at 250 ° C. for 30 minutes in a nitrogen atmosphere to form a polyimide film.

When a cell was produced, this substrate was rubbed under the following rubbing conditions in a rubbing direction such that the injected liquid crystal had a twist angle of 210 degrees, and then a liquid crystal cell was assembled.

Rubbing conditions 1. Roller radius with nylon brush 6cm 2. Roller rotation speed 800 rpm 3. Substrate moving speed 1 m / min 4. Number of substrate movements 2 times Liquid crystal cell assembled (cell thickness: 5.2 micrometer)
The liquid crystal used in Example 1 was injected into the substrate and a constant voltage (2 v) was applied.
Was applied to investigate the relationship between transmission law and frequency. The obtained results are shown in FIG. In the figure, the horizontal axis represents frequency (Hz) and the vertical axis represents transmittance.

Example 3 Synthesis of Alignment Film 0.1645 g of 3,6-diaminoacridine, 0.098 g of cyclobutanetetracarboxylic acid dianhydride and 10 millitorr of N-methyl-2-pyrrolidone were placed in a test tube and replaced with nitrogen. The reaction was carried out at 60 ° C for 5 hours with occasional stirring.

Preparation and Evaluation of Display Body The polyamic acid solution obtained by the above method was spin-coated (2000 rpm, 20 rpm) on the cell substrate of the liquid crystal display body.
Minute) and then baked at 250 ° C. for 30 minutes in a nitrogen atmosphere to form a polyimide film.

When a cell was produced, this substrate was rubbed under the following rubbing conditions in a rubbing direction such that the twist angle of the injected liquid crystal was 210 degrees, and then a liquid crystal cell was assembled.

Rubbing conditions 1. Roller radius with nylon brush 6cm 2. Roller rotation speed 800 rpm 3. Substrate moving speed 1 m / min 4. Number of substrate movements 2 times Liquid crystal cell assembled (cell thickness 5.1 micrometer)
The liquid crystal used in Example 1 was injected into the substrate and a constant voltage (2 v) was applied.
Was applied to investigate the relationship between transmission law and frequency. The obtained results are shown in FIG. In the figure, the horizontal axis represents frequency (Hz) and the vertical axis represents transmittance.

Example 4 Synthesis of Alignment Film 0.055 g of 2,5-diaminopyridine, 0.109 g of pittomellitic anhydride and 10 millitorr of N-methyl-2-pyrrolidone were placed in a test tube, and the atmosphere was replaced with nitrogen. The reaction was carried out for 5 hours while stirring occasionally.

Preparation and Evaluation of Display Body The polyamic acid solution obtained by the above method was spin-coated (2000 rpm, 20 rpm) on the cell substrate of the liquid crystal display body.
Minute) and then baked at 250 ° C. for 30 minutes in a nitrogen atmosphere to form a polyimide film.

When a cell was produced, this substrate was rubbed under the following rubbing conditions in a rubbing direction such that the twist angle of the injected liquid crystal was 210 degrees, and then a liquid crystal cell was assembled.

Rubbing conditions 1. Roller radius with nylon brush 6cm 2. Roller rotation speed 800 rpm 3. Substrate moving speed 1 m / min 4. Number of substrate movements 2 times Liquid crystal cell assembled (cell thickness 5.1 micrometer)
The liquid crystal used in Example 1 was injected into the substrate and a constant voltage (2 v) was applied.
Was applied to investigate the relationship between transmission law and frequency. The obtained results are shown in FIG. In the figure, the horizontal axis represents frequency (Hz) and the vertical axis represents transmittance.

Example 5 Synthesis of Alignment Film 3,5-diamino-1,2,4-triazole 0.0
495 grams, 0.109 grams of pyromellitic dianhydride, and 10 millitorr of N-methyl-2-pyrrolidone were placed in a test tube, and after substituting with nitrogen, the mixture was reacted at 60 ° C for 5 hours with occasional stirring.

Preparation and Evaluation of Display Body The polyamic acid solution obtained by the above method was spin-coated (2000 rpm, 20 rpm) on the cell substrate of the liquid crystal display body.
Minute) and then baked at 250 ° C. for 30 minutes in a nitrogen atmosphere to form a polyimide film.

When a cell was produced, this substrate was rubbed under the following rubbing conditions in a rubbing direction such that the twist angle of the injected liquid crystal was 210 degrees, and then a liquid crystal cell was assembled.

Rubbing conditions 1. Roller radius with nylon brush 6cm 2. Roller rotation speed 800 rpm 3. Substrate moving speed 1 m / min 4. Number of substrate movements 2 times Liquid crystal cell assembled (cell thickness 5.1 micrometer)
The liquid crystal used in Example 1 was injected into the substrate and a constant voltage (2 v) was applied.
Was applied to investigate the relationship between transmission law and frequency. The obtained results are shown in FIG. In the figure, the horizontal axis represents frequency (Hz) and the vertical axis represents transmittance.

Example 6 Synthesis of Alignment Film 3,6-Diaminoacridine 0.1045 g, pyromellitic dianhydride 0.109 g and N-methyl-2-pyrrolidone 10 millitorr were placed in a test tube, and after nitrogen substitution, 60 ° C. The reaction was carried out at C for 5 hours with occasional stirring.

Preparation and Evaluation of Display Body The polyamic acid solution obtained by the above method was spin-coated (2000 rpm, 20 rpm) on the cell substrate of the liquid crystal display body.
Minute) and then baked at 250 ° C. for 30 minutes in a nitrogen atmosphere to form a polyimide film.

During the cell fabrication, this substrate was rubbed under the following rubbing conditions in the rubbing direction so that the twist angle of the injected liquid crystal was 210 degrees, and then the liquid crystal cell was assembled.

Rubbing conditions 1. Roller radius with nylon brush 6cm 2. Roller rotation speed 800 rpm 3. Substrate moving speed 1 m / min 4. Number of substrate movements 2 times Liquid crystal cell assembled (cell thickness 5.1 micrometer)
The liquid crystal used in Example 1 was injected into the substrate and a constant voltage (2 v) was applied.
Was applied to investigate the relationship between transmission law and frequency. The obtained results are shown in FIG. In the figure, the horizontal axis represents frequency (Hz) and the vertical axis represents transmittance.

[0031]

As described in the above examples, the liquid crystal display using the novel alignment film of the present invention has very good frequency characteristics. For this reason, the contrast which is partially present in the conventional display body and which has a non-uniform display surface is eliminated, and a high quality display body can be provided. Further, since this alignment film is basically made of polyimide resin, there is no problem in terms of stability. The alignment film having such excellent properties is very useful as a basic material for the display portion of word processors and computers, which are expected to develop further.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross-sectional view of a liquid crystal display body.

FIG. 2 is a diagram showing a relationship between a transmittance and a frequency of a liquid crystal display body using the alignment film of the present invention.

FIG. 3 is a diagram showing a relationship between a transmittance and a frequency of a liquid crystal display body using a conventional general alignment film.

FIG. 4 is a diagram showing a relationship between a transmittance and a frequency of a liquid crystal display body using the alignment film of the present invention.

FIG. 5 is a diagram showing a relationship between a transmittance and a frequency of a liquid crystal display body using the alignment film of the present invention.

FIG. 6 is a diagram showing a relationship between a transmittance and a frequency of a liquid crystal display body using the alignment film of the present invention.

FIG. 7 is a diagram showing a relationship between a transmittance and a frequency of a liquid crystal display body using the alignment film of the present invention.

FIG. 8 is a diagram showing a relationship between a transmittance and a frequency of a liquid crystal display body using the alignment film of the present invention.

[Explanation of symbols]

 1: Glass substrate 2: Transparent electrode 3: Alignment film 4: Spacer 5: Liquid crystal 6: Compensation plate 7: Polarization plate

Claims (2)

[Claims] 1. A polyimide-based liquid crystal alignment film comprising a tetracarboxylic dianhydride-based compound and a diano-based compound, wherein the alignment film has nitrogen in addition to nitrogen in the imide bond. 2. A polyimide liquid crystal alignment film comprising a tetracarboxylic dianhydride compound and a diano compound,
A liquid crystal display characterized by using a polyimide compound having nitrogen other than imide-bonded nitrogen.