JP3171796B2 - Liquid crystal alignment agent - 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 aligning agent used for manufacturing a liquid crystal display device, and more particularly, to a liquid crystal aligning agent capable of obtaining a liquid crystal display device having a high pretilt angle and excellent stability. It is about.

[0002]

2. Description of the Related Art At present, liquid crystal display devices have been widely used as thin displays. A commonly used liquid crystal display device is a twisted nematic (T
N) method and super twisted nematic (STN) method.When these liquid crystal display elements are manufactured, as shown in JP-B-62-38689, a liquid crystal sandwiched between substrates with transparent electrodes is used as a substrate. On the other hand, a liquid crystal alignment film for aligning in a certain direction is required. Further, TN and STN type liquid crystal display devices require a pretilt angle for inclining and orienting liquid crystal with respect to a substrate surface, and this property is required for a liquid crystal aligning agent. For example, the STN method requires a pretilt angle of 4 to 8 degrees. Examples of the liquid crystal aligning agent capable of obtaining such a high pretilt angle include a polyimide precursor solution described in JP-A-1-177514 and a soluble polyimide solution described in JP-A-3-261915. No.
However, liquid crystal display devices manufactured using these liquid crystal aligning agents have insufficient pretilt stability, and in a high-temperature environment of 80 ° C or higher, the pretilt angle may decrease and display defects may occur. Has become.

On the other hand, as a method different from the above method for obtaining a high pretilt angle, there is a method of introducing a siloxane structure as described in JP-A-3-164714.
However, in the case of a siloxane structure, if the introduction ratio is high, the orientation of the liquid crystal becomes poor, so that the introduction may not be sufficient to obtain a sufficient pretilt angle.

[0004]

SUMMARY OF THE INVENTION The present invention is directed to a liquid crystal aligning agent which solves the above-mentioned problems of the liquid crystal aligning agent and which can obtain a high pretilt angle and a liquid crystal display element having excellent stability. It is.

[0005]

The present invention is a liquid crystal aligning agent containing a polyamide having a chemical structure represented by the formula (1) as a resin component.

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The polyamide of the present invention having the structure represented by the general formula (1) has a good liquid crystal orientation and a high pretilt angle.

The polyamide of the present invention having the structure represented by the general formula (1) is obtained by reacting 1,4-bis (3-aminopropyldimethylsilyl) benzene with dicarboxylic acid or dicarboxylic acid chloride in a polar solvent. Can be obtained by

Examples of dicarboxylic acids and dicarboxylic acid chlorides include succinic acid, adipic acid, 1,6-hexanedicarboxylic acid, 1,8-octanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid Acid, 1,3-cyclobutanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, 2,5-dimethylphenyldicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 3,
Examples include, but are not limited to, dicarboxylic acids such as 3'-biphenyldicarboxylic acid, 4,4'-benzophenonedicarboxylic acid, and acid chlorides thereof.

The polyamide having a structure represented by the general formula (1) of the present invention is 1,4-bis (3-aminopropyldimethylsilyl) as long as the effect of the structure represented by the general formula (1) is not impaired. ) Diamines other than benzene may be used as raw materials. Examples include 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-amino (Phenoxy)
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-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,10-diaminodecane, 1,12-diaminododecane 1,4-diaminocyclohexane, 4,4′-diaminodicyclohexylmethane, etc. Is not limited to these.

Examples of the polar organic solvent for performing polymerization for obtaining polyamide include, but are not limited to, N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, and γ-butyrolactone. .

The liquid crystal aligning agent comprises a resin component and a solvent component. Preferred examples of the solvent component of the liquid crystal aligning agent of the present invention include a mixed solvent of N-methyl-2-pyrrolidone (NMP) and butyl cellosolve, NMP And a mixed solvent of NMP and propylene glycol mono-n-butyl ether, a mixed solvent of NMP and propylene glycol diacetate, a mixed solvent of dimethylacetamide and butyl cellosolve, and the like, but are not limited thereto. Absent. Further, in order to further improve the adhesion to the substrate, a small amount of a silane coupling agent or a titanium-based coupling agent may be added.

[0013]

The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. (Synthesis Example 1) 25.24 g of 1,4-bis (3-aminopropyldimethylsilyl) benzene in a four-neck separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube.
(0.10 mol) and 20.24 g (0.20 mol) of triethylamine
Dissolve in 400 g of N-methyl-2-pyrrolidone (NMP). While maintaining the system at 10 ° C., 20.30 g (0.10 mol) of terephthaloyl chloride was charged from the raw material inlet, and stirring was continued for 5 hours. The resulting suspension was subjected to suction filtration, and the filtrate was dropped into 10-fold amount of methanol to separate a solid (polyamide) by filtration.
This solid was repeatedly dissolved / reprecipitated three times with an NMP / methanol system and then dried under reduced pressure at 80 ° C. for 24 hours. 5 g of the solid content after drying was mixed with an 8: 2 mixed solvent of NMP and butyl cellosolve (BCS) 9
It was dissolved in 5 g to obtain a liquid crystal aligning agent (1).

(Synthesis Example 2) 1,4-bis (3-aminopropyldimethylsilyl) was placed in a four-neck separable flask equipped with a thermometer, a stirrer, a dropping funnel, and a dry nitrogen gas inlet tube.
12.62 g (0.05 mol) of benzene, 20.53 g (0.05 mol) of 2,2-bis [4,4 '-(4-aminophenoxy) phenyl] propane,
Dissolve and disperse 17.22 g (0.10 mol) of 1,4-cyclohexanedicarboxylic acid and 15.82 g (0.20 mol) of pyridine in 200 g of NMP. A solution prepared by dissolving 41.27 g (0.20 mol) of dicyclohexylcarbodiimide in 123.81 g of NMP was added dropwise to this system from a dropping funnel, and stirring was continued for 5 hours while maintaining the system temperature at 100 ° C. The temperature of the system was lowered to room temperature, and the obtained suspension was filtered and then added dropwise to 10 times the amount of methanol to separate a solid (polyamide) by filtration. This solid was repeatedly dissolved / reprecipitated three times with an NMP / methanol system and then dried under reduced pressure at 80 ° C. for 24 hours. After drying, 5g of the solid content is NMP and butyl cellosolve (BC
It was dissolved in 95 g of an 8: 2 mixed solvent of S) to obtain a liquid crystal aligning agent (2).

Synthesis Example 3 20.53 g (0.05 mol) of 2,2-bis [4,4 ′-(4-aminophenoxy) phenyl] propane was
To bis [4,4 '-(4-aminophenoxy) phenyl] hexafluoropropane 25.92 g (0.05 mol), 17.22 g (0.10 mol) of 1,4-cyclohexanedicarboxylic acid and 11.81 g of succinic acid
(0.10 mol), and a liquid crystal aligning agent (3) was obtained in the same manner as in Synthesis Example 2.

Example 1 The liquid crystal aligning agent (1) obtained in Synthesis Example 1 was spin-coated on a glass substrate and dried in a clean oven at 170 ° C. for 120 minutes. This substrate was rubbed to form an anti-parallel cell having a cell gap of 50 μm. Liquid crystal (ZLI-2293 manufactured by Merck) was injected, heated to 100 ° C., and then gradually cooled to room temperature. Observation with a polarizing microscope showed that the orientation was good. The pretilt angle measured by the crystal rotation method was 7.1 degrees. After leaving this liquid crystal cell at 90 ° C. for 1000 hours, the pretilt angle was measured to be 7.1 °.

(Example 2) When the same procedure as in Example 1 was carried out using the liquid crystal aligning agent (2) obtained in Synthesis Example 2, the alignment was good, and the pretilt angle was 90 ° C before leaving for 1000 hours.
It was 6.2 degrees and 6.0 hours after 1000 hours.

Example 3 When the same procedure as in Example 1 was carried out using the liquid crystal aligning agent (3) obtained in Synthesis Example 3, the alignment was good, and the pretilt angle was 90 ° C. for 1000 hours.
It was 7.3 degrees and after 1000 hours it was 7.3 degrees.

Comparative Example 1 In a four-neck separable flask equipped with a thermometer, a stirrer, a dropping funnel, and a dry nitrogen gas inlet tube, 2,2-bis [4,4 '-(4-aminophenoxy)) was used. [Phenyl] propane 41.05 g (0.10 mol), 1,4-cyclohexanedicarboxylic acid 17.22 g (0.10 mol), pyridine 15.82 g (0.20 mol)
Mol) is dissolved and dispersed in 200 g of NMP. To this system, 41.27 g of dicyclohexylcarbodiimide (0.
(20 mol) in 123.81 g of NMP was added dropwise, and stirring was continued for 5 hours while maintaining the temperature of the system at 100 ° C. The temperature of the system was lowered to room temperature, and the obtained suspension was filtered and then added dropwise to 10 times the amount of methanol to separate a solid (polyamide) by filtration. Dissolve / reprecipitate this solid with NMP / methanol system.
After repeating this process twice, the resultant was dried under reduced pressure at 80 ° C. for 24 hours. 5 g of the solid content after drying was dissolved in 95 g of an 8: 2 mixed solvent of NMP and butyl cellosolve (BCS) to obtain a liquid crystal aligning agent (4). When the same procedure as in Example 1 was performed using the liquid crystal aligning agent (4), the alignment was good, and the pretilt angle was 90 ° C. for 1000 hours.
It was 2.0 degrees and after 1000 hours it was 2.0 degrees.

Comparative Example 2 In a four-necked separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube, 1,3-bis (3-aminopropyl) tetramethyldisiloxane was 24.85. g (0.10 mol), triethylamine 20.2
4 g (0.20 mol) are dissolved in 400 g of N-methyl-2-pyrrolidone (NMP). While maintaining the system at 10 ° C., 20.30 g (0.10 mol) of terephthaloyl chloride was charged from the raw material inlet, and 5
Stirring was continued for hours. The resulting suspension was subjected to suction filtration, and the filtrate was dropped into 10-fold amount of methanol to separate a solid (polyamide) by filtration. This solid was repeatedly dissolved / reprecipitated three times with an NMP / methanol system and then dried under reduced pressure at 80 ° C. for 24 hours. After drying, 5g of the solid content is NMP and butyl cellosolve (BC
The mixture was dissolved in 95 g of an 8: 2 mixed solvent of S) to obtain a liquid crystal aligning agent (5). When the same procedure was performed as in Example 1 using the liquid crystal aligning agent (5), the alignment was poor.

In Examples 1 to 3, good orientation was obtained.
A high pretilt angle of 6.0 to 7.3 degrees was obtained, and even after standing at 90 ° C for 1000 hours, the change in the pretilt angle was extremely small, indicating good stability.

In Comparative Example 1, the pretilt angle was as low as 2.0 degrees because polyamide having no chemical structure represented by the formula (1) was used as the liquid crystal aligning agent.

In Comparative Example 2, since the polyamide having a siloxane structure was used instead of the chemical structure represented by the formula (1), the orientation was poor.

[0024]

The liquid crystal aligning agent of the present invention is a liquid crystal aligning agent capable of stably obtaining good alignment and a high pretilt angle, and obtaining a liquid crystal display element having good display properties and high reliability.

Claims (1)

(57) [Claims] 1. A liquid crystal aligning agent containing a polyamide having a chemical structure represented by the formula (1) as a resin component. Embedded image