JPH1068950A - Liquid crystal orienting agnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal orienting agent with which a liquid crystal display excellent in reliability which does not cause display defects such as burning even used for a long time can be produced, by incorporating a resin component expressed by a specified repeating unit. SOLUTION: This orienting agnet contains a resin component expressed by the repeating unit of formula I. In formula, R is a quadrivalent aliphatic group, n is an integer >=2 and <=16, and k/l ranges from 1/4 to 24. R is preferably expressed by formula II and n is 4. This resin component is obtd. by the reaction of aliphatic tetracarboxylic acid dianhydride, aliphatic diamine and diaminosiloxane compd. in a polar org. solvent. As for the aliphatic tetracarboxylic acid diandhydride, for example, butane tetracarboxylic acid dianhydride and cyclobutane tetracarboxylic acid dianhydride are preferably used. As for aliphatic diamine, for example, ethylene diamine, 1,3- diaminopropane and 1,4-diaminobutane can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal aligning agent, and more particularly to a liquid crystal aligning agent suitable for forming an alignment film of a TN type, STN type or ferroelectric type 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]

SUMMARY OF THE INVENTION The present invention is a liquid crystal aligning agent which can solve the above-mentioned problems and can manufacture a liquid crystal display having excellent reliability.

[0005]

The present invention provides a liquid crystal aligning agent containing a resin component represented by a repeating unit of the general formula (1).

[0006]

Embedded image

(Wherein, R represents a tetravalent aliphatic group, n represents a number from 2 to 16; m represents a number from 1 to 10; k / l represents 1/4
From 24. Wherein R is represented by the formula (2)

[0008]

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Wherein n is 4.

The resin component in the liquid crystal aligning agent of the present invention can be obtained by reacting an aromatic tetracarboxylic dianhydride, an aliphatic diamine and a diaminosiloxane compound in a polar organic solvent. Preferred examples of the aliphatic tetracarboxylic dianhydride include butanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride,
1,2,4,5-cyclohexanetetracarboxylic dianhydride, bicyclo [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, 5- (2, 5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 3,4-dicarboxy-1 , 2,3,4-tetrahydro-1-naphthalene succinic dianhydride and the like, but are not limited thereto. Among these, the use of cyclobutanetetracarboxylic dianhydride is particularly favorable.

Examples of aliphatic diamines include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane,
Examples include, but are not limited to, 7-diaminoheptane, 1,8-diaminooctane, 1,10-diaminodecane, 1,12-diaminododecane, and the like. Among them, 1,4-diaminobutane is particularly preferable. As a liquid crystal aligning agent using an aliphatic diamine, there is a liquid crystal aligning agent described in JP-A-3-75727. However, in this example, the effect on display defects such as image sticking is not described and the purpose is to control the pretilt angle. Further, there is no description about the use of diaminosiloxane, and a problem to be solved and a method for solving the problem are different from those of the present invention.

Preferred examples of the diaminosiloxane compound include compounds represented by the general formula (3) wherein m, which is the number of repeating units of the siloxane, is 1 or more and 10 or less.

[0013]

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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.

[0016]

【Example】

Example 1 In a four-neck separable flask equipped with a thermometer, a stirrer, a dropping funnel, and a dry nitrogen gas inlet tube, 19.61 g (0.10 mol) of cyclobutanetetracarboxylic dianhydride was added.
Dissolve in 300 g of N-methyl-2-pyrrolidone (NMP). In a dropping funnel, 100 g of NMP, 9.30 g (0.08 mol) of 1,6-diaminohexane, and 6.45 g (0.02 mol) of the diaminosiloxane compound of formula (3) where m is 2 are uniformly dissolved. While maintaining the temperature of the system at 10 ° C. and stirring under nitrogen flow, the entire amount of the solution in the dropping funnel was dropped, and the solution was further cooled for 24 hours.
Stirring was continued for hours. The temperature of the system was returned to room temperature to obtain a polyamic acid NMP solution. This solution was diluted with NMP and butyl cellosolve such that the concentration of the resin component was 5% and the ratio of NMP to butyl cellosolve was 8: 2 to obtain a liquid crystal aligning agent.

This liquid crystal aligning agent is flexibly printed by IT.
O was applied on a glass substrate with a transparent electrode, and baked at 250 ° C. for 60 minutes in a clean oven to form an alignment film.
Using this substrate, a 240-degree twisted STN 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.
In addition, this liquid crystal cell was subjected to 1000 Hz
When the same test was performed after the time drive, a good display was obtained.

Examples 2 to 7 The same procedure was performed except that the aliphatic tetracarboxylic dianhydride, the aliphatic diamine and the diaminosiloxane compound were changed, and the results shown in Table 1 were obtained.

[0019]

[Table 1]

Comparative Example 1 9.30 g of 1,6-diaminohexane
(0.08 mol) was changed to 11.63 g (0.10 mol), and an STN liquid crystal cell was prepared in the same manner as in Example 1 except that no diaminosiloxane compound was added. 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 1000 hours, a similar test was carried out.

Comparative Example 2 9.30 g of 1,6-diamihexane
(0.08 mol) in 25.01 g of 1,20-diaminoeicosan (0.08
(Mol), to produce an STN liquid crystal cell. In this liquid crystal cell, the orientation of the liquid crystal was not uniform, and good display was not obtained.

COMPARATIVE EXAMPLE 3 6.45 g (0.02 mol) of bis (aminopropyl) siloxane of formula (3) wherein m is 2 was converted to 28.70 of bis (aminopropyl) siloxane of formula (3) wherein m was 16. An STN liquid crystal cell was prepared in the same manner as in Example 1 except that g (0.02 mol) was used. In this liquid crystal cell, the orientation of the liquid crystal was not uniform, and good display was not obtained.

(Comparative Example 4) 9.30 g of 1,6-diaminohexane
(0.08 mol) to 1.16 g (0.01 mol), m of general formula (3)
6.45 g of bis (aminopropyl) siloxane having a value of 2.
Example 1 except that 02 mol) was changed to 29.03 g (0.09 mol).
In the same manner as in the above, an STN liquid crystal cell was prepared. In this liquid crystal cell, the orientation of the liquid crystal was not uniform, and good display was not obtained.

Comparative Example 5 9.30 g of 1,6-diaminohexane
(0.08 mol) to 11.39 g (0.098 mol) of the general formula (3)
6.45 g of bis (aminopropyl) siloxane where m is 2
(STN liquid crystal cell) was prepared in the same manner as in Example 1 except that (0.02 mol) was changed to 0.65 g (0.002 mol). 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 1000 hours, a similar test was carried out.

In Examples 1 to 7, good display was obtained.
Even after driving for 1 hour with a rectangular wave of 1 Hz in an environment of 60 ° C., no unevenness was generated, and good display was obtained.

In Comparative Example 1, since bis (aminopropyl) siloxane was not added, the same test was conducted after driving for 1000 hours with a rectangular wave of 1 Hz in a 60 ° C. environment. Did not.

In Comparative Example 2, since n in the general formula (1) was a number exceeding 16, a square wave of 1 Hz at 60 ° C. and 1000 Hz was used.
Good display could not be obtained even before the time drive.

In Comparative Example 3, since m in the general formula (1) was a number exceeding 10, good display could not be obtained even after driving for 1 hour with a rectangular wave of 1 Hz in a 60 ° C. environment.

In Comparative Example 4, since k / l was less than 1/4, good display could not be obtained even before driving for 1000 hours with a rectangular wave of 1 Hz in a 60 ° C. environment.

In Comparative Example 5, since the value of k / l exceeded 24, a similar test was performed after driving for 1000 hours with a rectangular wave of 1 Hz in a 60 ° C. environment. could not.

[0031]

The liquid crystal aligning agent of the present invention is a liquid crystal aligning agent capable of producing a liquid crystal display which is less likely to deteriorate in display due to unevenness and has excellent reliability.

Claims (3)

[Claims] 1. A liquid crystal aligning agent containing a resin component represented by a repeating unit of the general formula (1). Embedded image (In the formula, R represents a tetravalent aliphatic group, n represents a number of 2 to 16, m represents a number of 1 to 10, and k / l is 1/4 to 24.) 2. The liquid crystal aligning agent according to claim 1, wherein R is represented by the formula (2). Embedded image 3. The liquid crystal aligning agent according to claim 2, wherein n is 4.