JPH1172794A - Polyimide precursor composition and liquid crystal orienting agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyimide precursor compsn. from which a liquid crystal orienting film is obtd. and a liquid crystal display with excellent reliability can be produced, by incorporating a specified repeating unit into the compsn. SOLUTION: The compsn. has a repeating unit expressed by formula I. In the formula, X is a quadrivalent org. group, and preferably a group expressed by formula II and/or formula III, R is H or alkyl group, and n is a number >=4 and <=16, and preferably 6 or 8. The polyimide precursor compsn. can be obtd. by the reaction of a tetracarboxylic acid dianhydride or its half-alkylester with a diamine expressed by formula IV in a polar org. solvent. In formula IV, n is a number >=4 and <=16. Thereby, by using the obtd. polyimide precursor compsn. and a liquid crystal orienting agent using this compsn., a liquid crystal display excellent in reliability with little deterioration in the display due to irregularity can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyimide precursor composition, and more particularly to a polyimide precursor composition and a liquid crystal alignment agent suitable for forming an alignment film of a liquid crystal display.

[0002]

2. Description of the Related Art Liquid crystal displays are used in many devices as thin, lightweight, low power displays. Conventionally, a method of using an organic polymer film such as polyvinyl alcohol, a polyamide resin, a polyamideimide resin, or a polyimide resin as an alignment film of a liquid crystal display has been known.

However, in recent years, as the characteristics of liquid crystal displays have been improved, it has been required that alignment layer materials have better characteristics than ever before. Specifically, in terms of the function of the liquid crystal alignment film, the liquid crystal alignment film exhibits excellent liquid crystal alignment properties and good electro-optical properties under various conditions, and has little deterioration with time. In conventional alignment agents, when used for recently developed low threshold voltage nematic liquid crystals, ferroelectric liquid crystals, and antiferroelectric liquid crystals, display failures such as image sticking occur when used for a long time. There is a problem.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above problems and provides a polyimide precursor composition capable of obtaining a liquid crystal alignment film capable of producing a liquid crystal display having excellent reliability, and a liquid crystal alignment using the same. Agent.

[0005]

The present invention provides: Polyimide precursor composition having a repeating unit represented by the general formula (1)

[0006]

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(Wherein, X represents a tetravalent organic group, R represents H or an alkyl group, and n represents a number of 4 or more and 16 or less), X is the above-mentioned polyimide precursor composition represented by the formula (2) and / or the formula (3)

[0008]

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[0009]

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[0010] 3. 3. The polyimide precursor composition as described above, wherein n is 6 or 8. A liquid crystal aligning agent containing the polyimide precursor composition as a resin component.

The polyimide precursor composition of the present invention can be obtained by reacting tetracarboxylic dianhydride or its half alkyl ester with a diamine represented by the general formula (4) in a polar organic solvent.

[0012]

Embedded image (In the formula, n represents a number of 4 or more and 16 or less.)

Examples of preferred tetracarboxylic dianhydrides include pyromellitic dianhydride, 3,3 ′,
4,4'-biphenyltetracarboxylic dianhydride, 3,3 ', 4,4'
-Benzophenonetetracarboxylic dianhydride, 3,3 ', 4,4'
-Diphenylsulfonetetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride , 1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5- (2 , 5-dioxotetrahydrofuryl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 3,4-dicarboxy-1,2 , 3,4-tetrahydro-1-naphthalenesuccinic dianhydride and the like, but are not limited thereto. Also, two or more of these may be used simultaneously. Of these, the use of pyromellitic dianhydride and / or cyclobutanetetracarboxylic dianhydride is particularly favorable.

When R in the general formula (1) is an alkyl group, methanol, ethanol, 1-propanol, 2-
It can be obtained by reacting an alcohol such as propanol with a tetracarboxylic dianhydride to form a tetracarboxylic diester and then dehydrating and condensing with a diamine, or by dehydrating and condensing an alcohol and a polyamic acid.

As the diamine, those having the structure represented by the general formula (4) are used, and those in which n is 6 or 8 are particularly preferable.

The polyimide precursor of the present invention having the structure represented by the general formula (1) may use another diamine as a raw material as long as the effect of the structure represented by the general formula (1) is not impaired. Absent. For example, p-phenylenediamine, m-
Phenylenediamine, 2,5-diaminotoluene, 3,5-diaminotoluene, 2,5-diamino-p-xylene, 3,3'-dimethylbenzidine, 3,4'-diaminodiphenyl ether, 4,
4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 1,3-
(3-aminophenoxy) benzene, 1,3- (4-aminophenoxy) benzene, 1,4- (3-aminophenoxy) benzene,
1,4- (4-aminophenoxy) benzene, 4,4 '-(4-aminophenoxy) biphenyl, 2,2-bis [4,4'-(4-aminophenoxy) phenyl] propane, 2,2- Bis [4,4 '-(4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis
[4,4 '-(4-aminophenoxy) phenyl] sulfone, 1,3-
Bis (4-aminophenoxy) propane, 1,4-bis (4-aminophenoxy) butane, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diamino Hexane, 1,7-diaminoheptane, 1,
Examples include, but are not limited to, 8-diaminooctane, 1,10-diaminodecane, 1,12-diaminododecane 1,4-diaminocyclohexane, and 4,4′-diaminodicyclohexylmethane.

Preferred examples of the organic polar solvent used in the reaction include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, γ-butyrolactone, m-cresol, and the like. Absent.

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

[0019]

【Example】

Example 1 27.23 g (0.10 mol) of 1,4-bis (4-aminophenoxy) butane 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. N-
Dissolve in 300 g of methyl-2-pyrrolidone (NMP).
After charging 21.81 g (0.10 mol) of pyromellitic dianhydride from the raw material inlet, stirring was continued for 5 hours while stirring under nitrogen inflow while maintaining the system temperature at 10 ° C. The temperature of the system was returned to room temperature to obtain a polyimide precursor composition which was an NMP solution of polyamic acid. This polyimide precursor composition was treated with NM
With P and butyl cellosolve, the concentration of resin component is 5%,
The mixture was diluted so that the ratio of NMP to butyl cellosolve was 8: 2 to obtain a liquid crystal aligning agent. This liquid crystal aligning agent was applied on a glass substrate with an ITO transparent electrode by flexographic printing, and baked at 250 ° C. for 60 minutes in a clean oven to form an alignment film. Using this substrate, a TN liquid crystal cell having a cell gap of 6 μm was prepared using a liquid crystal having a threshold voltage of 1.0 V according to a conventional method. The display of this liquid crystal cell was good. Further, when this liquid crystal cell was driven in a 60 ° C. environment with a rectangular wave of 1 Hz for 1,000 hours, a similar test was performed, and good display was obtained.

(Example 2) In a four-neck separable flask equipped with a thermometer, a stirrer, a dropping funnel, and a dry nitrogen gas introducing tube, 21.81 g (0.10 mol) of pyromellitic dianhydride was prepared.
6.41 g (0.20 mol) of methanol are dissolved in 200 g of NMP. 15.82 g (0.20 mol) of pyridine was added dropwise from the dropping funnel, and the reaction was allowed to proceed at 25 ° C. for 16 hours. In another dropping funnel, 41.27 g (0.20 mol) of dicyclohexylcarbodiimide was added with N
It was dissolved in 100 g of MP, attached and dropped into the system.
After dripping, 1,6-bis (4-aminophenoxy) hexane 30.04 g
(0.10 mol), and stirring was continued at 25 ° C. for 5 hours. The resulting suspension was filtered to remove dicyclohexylcarbodiurea, and NMP of polyamic acid methyl ester was removed.
A solution of the polyimide precursor composition was obtained. This polyimide precursor composition by NMP and butyl cellosolve,
The liquid crystal aligning agent was diluted so that the concentration of the resin component was 5% and the ratio of NMP to butyl cellosolve was 8: 2. Thereafter, a TN liquid crystal cell was prepared in the same manner as in Example 1. The display of this liquid crystal cell was good. In addition, this liquid crystal cell
When the same test was performed after driving for 500 hours and 1000 hours with a 1 Hz rectangular wave in an environment of 60 ° C., good display was obtained in each case.

Examples 3 to 8 The same procedure as in Example 1 was carried out except that the tetracarboxylic dianhydride and the diamine were changed, and the results shown in Table 1 were obtained.

[0022]

[Table 1]

Comparative Example 1 27.23 g (0.10 mol) of 1,4-bis (4-aminophenoxy) butane was converted to 41.05 g (0.10 mol) of 2,2-bis (4,4 '-(4-aminophenoxyphenyl) propane. TN liquid crystal cell was produced in the same manner as in Example 1 except that the liquid crystal cell was replaced with the same compound (mol), and the display of this liquid crystal cell was good. When a similar test was performed, unevenness in shading occurred, and good display could not be performed.

Comparative Example 2 Except that 27.23 g (0.10 mol) of 1,4-bis (4-aminophenoxy) butane was changed to 25.83 g (0.10 mol) of 1,3-bis (4-aminophenoxy) propane A TN liquid crystal cell was formed in the same manner as in Example 1. The display of this liquid crystal cell was good. When this liquid crystal cell was driven in a 60 ° C. environment with a rectangular wave of 1 Hz for 500 hours, a similar test was carried out.

Comparative Example 3 Except that 27.23 g (0.10 mol) of 1,4-bis (4-aminophenoxy) butane was changed to 49.68 g (0.10 mol) of 1,20-bis (4-aminophenoxy) eicosane A TN liquid crystal cell was formed in the same manner as in Example 1. In this liquid crystal cell, the orientation of the liquid crystal was not uniform, and good display was not obtained.

In Examples 1 to 8, good display without unevenness was obtained, and even after driving for 500 hours with a 1 Hz rectangular wave in a 60 ° C. environment, good display was obtained without unevenness. Equation 2 and Equation 3
In the case where n is 6 or 8, the display after 1000 hours did not show unevenness and was particularly excellent.

In Comparative Example 1, since the diamine having the structure represented by the general formula (4) was not used, the same test was performed after driving for 500 hours under a 60 ° C. environment with a rectangular wave of 1 Hz. Good display could not be obtained.

In Comparative Example 2, since n in the general formula (1) was less than 4, a similar test was conducted after driving for 500 hours with a rectangular wave of 1 Hz in a 60 ° C. environment, and unevenness in shading occurred. No good display was obtained.

In Comparative Example 3, since n in the general formula (1) was a number exceeding 16, good display was not obtained even before driving for 500 hours with a rectangular wave of 1 Hz in a 60 ° C. environment.

[0030]

As described above, the polyimide precursor composition of the present invention and the liquid crystal aligning agent using the same can produce a liquid crystal display having little reliability and excellent display reliability due to unevenness.

Claims (4)

[Claims] 1. A polyimide precursor composition having a repeating unit represented by the general formula (1). Embedded image (In the formula, X represents a tetravalent organic group, R represents H or an alkyl group, and n represents a number of 4 or more and 16 or less.) 2. The polyimide precursor composition according to claim 1, wherein X is the formula (2) and / or the formula (3). Embedded image Embedded image 3. The polyimide precursor composition according to claim 1, wherein n is 6 or 8. 4. A liquid crystal aligning agent comprising the polyimide precursor composition according to claim 1 as a resin component.