JPH07287235A - Liquid crystal orienting agent and liquid crystal display element using the same - Google Patents

Abstract

PURPOSE:To make it possible to obtain an oriented film which is workable at a low temp. and is high in pretilt angle by using a polyamide having a straight chain alkyl structure at the terminal of the molecule and a polyamide acid having an aliphat. tetracarboxylic acid structure as esiential components. CONSTITUTION:This liquid crystal orienting agent is composed of the polyamide which is capable of exhibiting the high pretilt angle in spite of low-temp. baking and the polyamide acid which has the aliphat. tetracarboxylic acid structure exhibiting a good adhesion property and electrical characteristics as the essential components. The ratio of the polyamide having the long chain alkyl structure and the polyamino acid having the aliphat. tetracarboxylic acid structure is preferably 0.05/0.95 to 0.95/0.05 by weight in order to attain compatibility of these characteristics. The polyamide is provided with a good effect of suppressing particularly the electric current consumption to a low level by having the aliphat. tetracarboxylic acid structure. As a result, the oriented film which is workable at a low temp. of <=150 deg.C, has the good adhesion property to the substrate and rubbing resistance and exhibits the high pretilt angle is obtd.

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 in the manufacture of liquid crystal display devices, and more specifically, it can be processed at low temperatures and has excellent adhesion to a substrate and rubbing resistance and exhibits a high pretilt angle. The present invention relates to a liquid crystal aligning agent capable of obtaining a liquid crystal aligning film, and to a liquid crystal display device using this liquid crystal aligning agent and having excellent reliability.

[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 element is a twisted nematic (T
The N) method and the super twisted nematic (STN) method are used. However, when manufacturing these liquid crystal display elements, the liquid crystal sandwiched between the substrates with transparent electrodes is used as a substrate as shown in Japanese Patent Publication No. 62-38689. On the other hand, a liquid crystal alignment film that aligns in a fixed direction is required. An item required for the liquid crystal aligning agent for STN is that the angle formed by the alignment direction of the liquid crystal molecules and the substrate, that is, the pretilt angle is 4 to 8 degrees, which is higher than that for the twisted nematic (TN) type. Examples of the liquid crystal aligning agent capable of obtaining such a high pretilt angle include a polyimide precursor solution as described in JP-A-1-177514.

Generally, a substrate of a liquid crystal display device has a thickness of 0.3 mm.
Glass with a thickness of about 1.0 mm is used. recent years,
In order to further reduce the thickness and weight of electronic devices equipped with liquid crystal display elements, polyethylene terephthalate (hereinafter abbreviated as PET) or polyether sulfone (hereinafter PES) is used as the substrate.
Abbreviated. ), The use of a plastic substrate such as polyarylate has been studied, and some have begun to put it into practical use. By using these plastic substrates,
It can be made thinner and lighter, and it is also possible to manufacture a display with a curved display surface or a flexible display by taking advantage of the flexibility of plastics.

However, in manufacturing such a plastic liquid crystal display device, there arises a problem regarding a liquid crystal aligning agent used therein. That is, since a plastic substrate is used, about 120 ° C. for PET, about 150 ° C. for PES or polyarylate is the maximum temperature allowed in the process, and the liquid crystal aligning agent for STN as described above whose firing temperature is 200 to 300 ° C. Is that you cannot use.

On the other hand, as a liquid crystal aligning agent which can be baked at 200 ° C. or lower, a liquid crystal aligning agent containing a soluble polyimide as a resin component described in JP-A-61-205924 and JP-A-5-158047 are disclosed. A liquid crystal aligning agent containing a silicone-modified polyamic acid as a resin component has been proposed. The former is because the resin component is not a polyimide precursor, but a polyimide that has already been imidized,
The alignment film can be obtained by evaporating the solvent. In the latter case, thermal imidization is more likely to proceed than a normal polyimide precursor, and therefore firing at low temperature is possible. However, although they exhibit sufficient performance when fired at 150 to 200 ° C, a sufficient pretilt angle cannot be obtained at a firing temperature of less than 150 ° C, or the stability is insufficient and the pretilt angle is increased by an accelerated test. A phenomenon such as a change may occur. It has become a problem about yield and reliability of plastic liquid crystal display elements.

Further, when a liquid crystal aligning agent containing soluble polyimide as a resin component is used, the adhesiveness between the alignment film and the substrate is not sufficient and the alignment film may peel off in the rubbing process. The polyimide used as the alignment film is required to have a highly linear and rigid structure for uniaxially aligning the liquid crystal, but the polyimide having such a structure has a glass transition temperature of 150 ° C. or higher, and is high at a temperature below this. It is essentially impossible to obtain adhesion. On the other hand, when a liquid crystal aligning agent containing a silicone-modified polyamic acid as a resin component is used, the glass transition temperature during film formation is low and the adhesion is good, but if the temperature is lower than 150 ° C., imidization does not proceed sufficiently and liquid crystals are formed. It is not possible to obtain an orientation property for uniform uniaxial orientation.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above problems of liquid crystal aligning agents, can be processed at a low temperature of 150 ° C. or less, has good adhesion to a substrate, and is excellent in rubbing resistance and high. The present invention provides a liquid crystal aligning agent capable of obtaining an alignment film exhibiting a pretilt angle, and a liquid crystal display device using this liquid crystal aligning agent, which has a high yield and is excellent in reliability.

[0008]

The present invention is directed to a liquid crystal aligning agent containing a polyamide having a linear alkyl structure at a molecular end and a polyamic acid having an aliphatic tetracarboxylic acid structure as essential components, and a liquid crystal display using the same. It is an element.

The liquid crystal aligning agent of the present invention requires a polyamide having a linear alkyl structure capable of exhibiting a high pretilt angle even at low temperature firing and a polyamic acid having an aliphatic tetracarboxylic acid structure exhibiting good adhesion and electric characteristics. It is a liquid crystal aligning agent as a component. In order to achieve both of these characteristics, the weight ratio of the polyamide having a long-chain alkyl structure to the polyamic acid having an aliphatic tetracarboxylic acid structure is preferably 0.05 / 0.95 to 0.95 / 0.05.

As mentioned above, a soluble polyimide is generally used as a resin component of a liquid crystal aligning agent that can be fired at a low temperature of 150 ° C. or lower. However, since the soluble polyimide is incompatible with the polyamic acid, it is not compatible with the polyamic acid. It is impossible to improve the adhesion by using them together. On the other hand, the polyamide of the present invention and the polyamic acid show good compatibility, and a uniform and transparent state can be obtained both in the state of solution and in the state of forming an alignment film.

The structure of the polyamic acid is as follows:
The one having an aromatic tetracarboxylic acid structure as shown in Japanese Patent No. 38689 is more general and good adhesion can be achieved by using this, but compared with a polyamic acid having an aliphatic tetracarboxylic acid structure Since it is susceptible to decomposition, imidization does not proceed sufficiently, it lacks long-term stability when used by baking at 150 ° C or lower, causing an electrical characteristic problem that increases the current consumption in the reliability test of liquid crystal display elements. There is a case. These problems do not occur when the polyamic acid having an aliphatic tetracarboxylic acid structure in the present invention is used. Furthermore, when the polyamide has an aliphatic dicarboxylic acid structure, the effect of suppressing the current consumption is particularly good. Among these structures, when the polyamide is the structure represented by the general formula (1) or the general formula (2) and the polyamic acid is the structure represented by the general formula (3), stability of orientation is particularly high. Excellent and preferable.

[0012]

[Chemical 1]

[0013]

[Chemical 2]

[0014]

[Chemical 3]

[0015]

[Chemical 4]

Further, when R ₄ in the general formula (4) is represented by —CH ₂ —, the stability of orientation is particularly excellent among these.

Among the structures of the polyamides represented by the general formulas (1) and (2) in the liquid crystal aligning agent of the present invention, R ₁ ,
The straight chain alkyl group of R ₂ imparts a high pretilt angle of 3 degrees or more. The carbon number of R ₁ and R ₂ is 4 or more and 30 or less. When the number of carbons is 3 or less, the effect of giving the pretilt angle cannot be clearly obtained. It deteriorates, and good display cannot be obtained.

The polyamide having a linear alkyl structure in the liquid crystal aligning agent of the present invention can be obtained by dehydration condensation of a linear alkylcarboxylic acid or a linear alkylamine, a dicarboxylic acid and a diamine in a polar solvent, or a linear alkylcarboxylic acid. It can be obtained by reacting chloride or linear alkylamine, dicarboxylic acid chloride and diamine in a polar solvent.

The linear alkyl carboxylic acid, linear alkyl carboxylic acid chloride, and linear alkyl amine preferably have an alkyl chain length of 4 or more and 30 or less for the above reason.

Examples of dicarboxylic acids include 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, succinic acid, adipic acid, 1,6-diaminohexane, 1,7. -Diaminoheptane, 1,8-diaminooctane, 1,10-diaminodecane, dodecanedioic acid, terephthalic acid, isophthalic acid, 4,4'-oxydibenzoic acid, 4,4'-sulfonyldibenzoic acid, 2,2 Examples thereof include, but are not limited to, -bis (4-carboxyphenyl) propane and 2,2-bis (4-carboxyphenyl) hexafluoropropane. When the acid chloride is used, as an example of, a dicarboxylic acid chloride corresponding to the above dicarboxylic acid can be mentioned.
It is not limited to these. Also, two or more kinds can be used simultaneously. Of these dicarboxylic acid components, 1,4-cyclohexanedicarboxylic acid that gives an aliphatic dicarboxylic acid structure, 1,2-cyclohexanedicarboxylic acid,
1,3-cyclohexanedicarboxylic acid, succinic acid, adipic acid, 1,6-diaminohexane, 1,7-diaminoheptane, 1,
8-diaminooctane, 1,10-diaminodecane, dodecanedioic acid or an acid chloride thereof is preferably used, and more preferably 1,4-cyclohexanedicarboxylic acid or an acid chloride thereof is used.

As the diamine used as a raw material for polyamide in the present invention, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 1 , 3- (4-aminophenoxy) benzene, 2,2-bis
[4,4 '-(4-Aminophenoxy) phenyl] propane, 2,2-
Aromatic diamines such as bis [4,4 '-(4-aminophenoxy) phenyl] hexafluoropropane and 1,2-ethylenediamine, tetramethylenediamine, 1,5-diaminopentane, 1,6-diaminohexane, 1, 7-diaminoheptane, 1,
8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,4-diaminocyclohexane, 1,3-bis
Aliphatic diamines such as (aminomethyl) cyclohexane and 4,4′-diaminodicyclohexylmethane are not limited to these. Further, Ar ₁ in the general formulas (1) and (2) is a diamine having the general formula (3).
2,2-bis (4,4 '-(4-aminophenoxy) phenyl) 4,
4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 1,4-
Bis (4-aminophenoxy) benzene, 2,2-bis [4,4 '-(4
-Aminophenoxy) phenyl] propane, 2,2-bis [4,4 '
-(4-aminophenoxy) phenyl] hexafluoropropane is preferable from the viewpoint of obtaining good uniaxial orientation, and 4,4'-diamino in which R ₄ in the general formula (4) is -CH _2-. More preferably, it is diphenylmethane. Also,
In the present invention, it is possible to use two or more kinds of diamines.

The polyamic acid having an aliphatic tetracarboxylic acid structure in the present invention can be obtained by reacting an aliphatic tetracarboxylic dianhydride with a diamine in a polar solvent. Examples of the aliphatic tetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic acid Dianhydride, 5- (2,5-dioxotetrahydrofuranyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, bicyclo [2,2,2] oct-7-ene, 1, 3,3a, 4,5,9b-
Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, bicyclo [2,2,
1] heptane-2,3,5,6-tetracarboxylic dianhydride, 2,3,5
-Tricarboxycyclopentyl acetic acid dianhydride and the like are included, but not limited thereto. Also, two or more kinds may be used in combination. Among these aliphatic tetracarboxylic dianhydrides, butanetetracarboxylic dianhydride or 5- (2,5-dioxotetrahydrofuranyl) -3-
More preferably, methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride is used.

Examples of the diamine used as a raw material for the polyamic acid having an aliphatic tetracarboxylic acid structure in the present invention include p-phenylenediamine, m-phenylenediamine, 2,5-diaminotoluene, 3,5-diaminotoluene,
2,5-diaminoxylene, 3,3'-dimethylbenzidine, 3,
4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-
Diaminodiphenyl sulfone, 1,3- (4-aminophenoxy) benzene, 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, ethylenediamine, hexamethylenediamine, 1,7-diaminopentane, 1,8-diaminooctane and the like, but not limited thereto. Among these diamines, it is more preferable to use 4,4′-diaminodiphenylmethane.

[0024] a structure represented by the general formula (1) in the present invention the polyamide, R _1, an alkyl carboxylic acid chloride with an alkyl carboxylic acid or R _1, the R ₂ structure having a structure of R ₂ and H It can be obtained by reacting a diamine represented by ₂ N-Ar-NH ₂ with 1,4-diaminocyclohexane or an acid chloride thereof. The polyamide represented by the general formula (2) can be obtained by adding an alkyldiamine having a structure of R ₁ and R ₂ instead of the above-mentioned alkyldicarboxylic acid or alkylcarboxylic acid chloride.

The liquid crystal aligning agent is composed of 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 ethyl carbitol, a mixed solvent of dimethylacetamide and butyl cellosolve, and the like, but are not limited thereto. Furthermore, a silane coupling agent or a titanium-based coupling agent may be added in a trace amount in order to further improve the adhesion to the substrate.

When a liquid crystal display device is manufactured using the liquid crystal aligning agent of the present invention, the liquid crystal aligning agent is applied on a substrate with a transparent electrode by flexographic printing, spin coating, dipping, etc., and 100 ° C. to 250 ° C. Preferably, after baking at 110 ° C to 150 ° C, rubbing is performed. A cell in which a sealant is printed is made to face the periphery of this substrate to assemble a cell in which a gap is held by a spacer, a liquid crystal is injected, the injection port is sealed, and a polarizing plate is attached to form a liquid crystal display element. The alignment film develops an alignment regulating force by rubbing after firing, but its ability may be reduced if treated at a temperature higher than the firing temperature after rubbing. Therefore, it is preferable that the highest temperature process is the alignment film baking process.

As the substrate with a transparent electrode used in the liquid crystal display device of the present invention, a substrate with a color filter having a lower heat resistance than the most general glass / ITO substrate or a plastic substrate having a lower heat resistance can be used. it can. Preferred examples of the plastic substrate include, but are not limited to, polyethylene terephthalate (abbreviated as PET), polyether sulfone (PES), polycarbonate (PC), polyarylate, and the like.

[0028]

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

(Synthesis Example 1) In a four-necked separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube, 19,83 g (0.100 g) of 4,4'-diaminodiphenylmethane was prepared.
Mol), triphenyl phosphite 62.06 g (0.200 mol) N
-Dissolve in a mixed solvent of 300 g of methyl-2-pyrrolidone (NMP) and 75 g of pyridine. To this system, 16.36 g (0.095 mol) of 1,4-cyclohexanedicarboxylic acid and 15.0 g of lithium chloride were charged from the raw material charging port, and the temperature of the system was kept at 100 ° C.
Stirring was continued for hours. Continue to lauric acid from the raw material inlet 2.
003 g (0.010 mol) was added and stirring was continued for 10 hours while maintaining the system temperature at 100 ° C. The temperature of the system was lowered to room temperature, the obtained suspension was added dropwise to 10 liters of methanol, and the solid content was filtered off. Dissolve this solid content in NMP / methanol system /
After reprecipitation was repeated 3 times, it was dried under reduced pressure at 80 ° C. for 24 hours. After drying, 5 g of solid content was added to NMP and butyl cellosolve (BCS)
A polyamide solution (a) having a concentration of 5% was obtained by dissolving it in 95 g of a mixed solvent for 3.

(Synthesis Example 2) 2,2-bis [4,4 '-(4-aminophenoxy) 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. ) Phenyl] propane 41.05 (0.100 mol), triethylamine 20.
Dissolve 24 g in 400 g NMP. While keeping the temperature of the system at 5 ° C, 19.29 g (0.
(095 mol) was added, stirring was continued for 2 hours while maintaining the system temperature at 5 ° C., 2.348 g (0.010 mol) of lauric chloride was added from the raw material charging port, and stirring was continued for 5 hours while maintaining at 5 ° C. . The temperature of the system was returned to room temperature, the obtained liquid was filtered and then added dropwise to 10 liters of methanol, and the solid content was separated by filtration. This solid content was dissolved / reprecipitated again in 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 dissolved in 95 g of a 7/3 mixed solvent of NMP and BCS to obtain a polyamide solution (b) having a concentration of 5%.

(Synthesis Example 3) 18.84 g (0.095 g) of 4,4'-diaminodiphenylmethane 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.
Mol), 1.854 g of laurylamine (0.010 mol) and 20.24 g of triethylamine are dissolved in 375 g of NMP. System temperature is 5 ℃
Then, 20.91 g (0.100 mol) of 1,4-cyclohexanedicarboxylic acid chloride was charged from the raw material charging port, and stirring was continued for 3 hours while maintaining the system temperature at 5 ° C. The temperature of the system was returned to room temperature, and the obtained suspension was filtered. The filtrate was dropped into 10 liters of methanol, and the solid content was filtered off. After this solid content was dissolved / reprecipitated again in NMP / methanol system, 8
It was dried under reduced pressure at 0 ° C. for 24 hours. Dissolve 5 g of the dried solid in 95 g of a 7/3 mixed solvent of NMP and butyl cellosolve to give a concentration of 5
% Polyamide solution (c) was obtained.

Synthesis Example 4 In Synthesis Example 1, 16.87 g of 1,4-cyclohexanedicarboxylic acid (16.36 g (0.095 mol)) was added.
A polyamide solution (d) was obtained in the same manner as in (0.098 mol) except that lauric acid (2.003 g, 0.010 mol) was changed to stearic acid (1.138 g, 0.004 mol).

Synthesis Example 5 In Synthesis Example 1, 16.36 g (0.095 mol) of 1,4-cyclohexanedicarboxylic acid was added to 16.70 g.
Polyamide solution (e) was obtained in the same manner as above, except that 2.003 g (0.010 mol) of lauric acid was replaced with 1.539 g (0.006 mol) of palmitic acid.

(Synthesis Example 6) In Synthesis Example 1, 19,83 g (0.100 mol) of 4,4'-diaminodiphenylmethane was added to 29.23 g (0.100 mol) of 1,4-bis (4-aminophenoxy) benzene and 1,4 -Cyclohexanedicarboxylic acid 16.36 g (0.095
A polyamide solution (f) was obtained in the same manner except that 13.88 g (0.095 mol) of adipic acid was used instead of adipic acid.

(Synthesis Example 7) In Synthesis Example 1, 19,83 g (0.100 mol) of 4,4'-diaminodiphenylmethane was added to 20.02 g (0.100 mol) of 4,4-diaminodiphenyl ether and 1,4
-A polyamide solution (g) was obtained by performing the same synthesis except that 16.36 g (0.095 mol) of cyclohexanedicarboxylic acid was replaced with 11.22 g (0.095 mol) of succinic acid.

(Synthesis Example 8) In Synthesis Example 3, 1.854 g (0.010 mol) of laurylamine was replaced with 1.293 g (0.10 mol) of n-octylamine.
A polyamide solution (h) was obtained in the same manner except that the amount was changed to 010 mol).

Synthesis Example 9 In a four-necked separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube, 19,83 g (0.100 g) of 4,4'-diaminodiphenylmethane was prepared.
Mol) in 300 g of NMP. 19.81 g (0.100 mol) of butanetetracarboxylic dianhydride was added to this system and reacted at 0-10 ° C for 12 hours under an inflow of dry nitrogen to synthesize a polyamic acid. NMP and BCS are added to this solution and the solvent composition is NMP / BCS = 7.
A polyamic acid solution (A) having a concentration of / 5, which is 5%, was obtained.

Synthesis Example 10 In Synthesis Example 9, 4,4'-
Diaminodiphenylmethane 19.83 g (0.100 mol) 1,4-
A polyamic acid solution (B) was obtained in the same manner except that 8.815 g (0.100 mol) of tetramethylenediamine was used.

Synthesis Example 11 In Synthesis Example 9, 19.81 g (0.100 mol) of butanetetracarboxylic dianhydride was added to 5- (2,
5-Dioxotetrahydrofuranyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride 26.42 g (0.100 mol)
A polyamic acid solution (C) was obtained in the same manner except that it was replaced with.

(Synthesis Example 12) In Synthesis Example 9, 19.81 g (0.100 mol) of butanetetracarboxylic dianhydride was added to 19.61 g (0.100 mol) of cyclobutanetetracarboxylic dianhydride.
In addition, 19.83 g (0.100 mol) of 4,4'-diaminodiphenylmethane was added to 24.83 g (0.100 mol) of 4,4'-diaminodiphenylsulfone.
Polyamide acid solution (D)
Got

(Synthesis Example 13) In Synthesis Example 9, 19.81 g (0.100 mol) of butanetetracarboxylic dianhydride was added to 21.01 g (0.100 mol) of cyclopentanetetracarboxylic dianhydride and 4,4'-diaminodiphenylmethane. 19.83g (0.100
20.02 g (0.1 mol) of 4,4'-diaminodiphenyl ether
A polyamic acid solution (E) was obtained in the same manner except that the amount was changed to 00 mol).

Example 1 50 parts by weight of the polyamide solution (a) obtained in Synthesis Example 1 and 50 g by weight of the polyamic acid solution (A) obtained in Synthesis Example 9 were mixed to prepare a liquid crystal aligning agent. This liquid crystal aligning agent was printed on a polyether sulfone substrate having an ITO electrode having an area of 1 cm @ 2 using a flexographic printing machine and heated in a dryer at 120 DEG C. for 2 hours to form an alignment film on the substrate.
Using a rubbing roll with a diameter of 4 cm, in which nylon yarn with a length of 2 mm was electrostatically flocked, a rubbing was performed with a tip pushing length of 0.5 mm, a roll speed of 1500 rpm, and a table feed speed of 10 cm / min. No peeling was observed.

The two substrates are opposed to each other in such a manner that the rubbing directions are antiparallel to each other, a spacer of 50 μm is sandwiched between the substrates and the periphery is sealed with an epoxy resin, and a liquid crystal (ZLI-Merck ZLI-
2293) was injected to prepare a liquid crystal cell. When this liquid crystal cell was sandwiched between two polarizing plates and the orientation was observed, no unevenness or defects were observed and good orientation was exhibited. When the pretilt angle was measured by the crystal rotation method,
It was 7 degrees. Furthermore, after the liquid crystal cell was left in a constant temperature bath at 90 ° C. for 1 week, the orientation and the pretilt angle were similarly confirmed. No change was observed in the orientation and the pretilt angle was 7 degrees.

An STN type liquid crystal display device having a cell gap of 7 μm and a twist angle of 240 ° was manufactured by using the substrate on which the alignment film was formed in the same manner as described above. At this time, the curing of the sealant
Performed at 120 ° C. The liquid crystal was used by adding a chiral agent to the above liquid crystal. When the display property of this liquid crystal display element when not driven was visually confirmed, it was good with no unevenness or defects. When the liquid crystal display device was driven by a rectangular wave of 33 Hz, ± 5 V, the consumption current was measured and found to be 0.9 μA. Furthermore, when the display property when driven was confirmed, no unevenness or defects were found and it was good. When this liquid crystal display device was left in a constant temperature bath at 90 ° C. for 1 week, the current consumption was measured in the same manner to find that it was 0.9 μA. When the display property was confirmed, no unevenness or defects were found and it was good.

(Examples 2 to 9) Example 2 was repeated except that the combination of polyamide and polyamic acid and the twist angle of the liquid crystal display device were changed as shown in Table 1.

[0046]

[Table 1]

Comparative 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 NMP. To this system, using a dropping funnel, 9.2-g (0.04 mol) of 1,2-bis (aminopropyl) tetramethyldisiloxane was dropped, and after the dropping, reaction was carried out for 1 hour while maintaining the temperature of the system at 20 ° C. . Next, 2,2-bis (4
-(4-Aminophenoxy) phenyl) propane 16.42 g (0.04
Mol) was added all at once, and stirring was continued for 5 hours while maintaining the temperature at 20 ° C. to obtain a silicone-modified polyamic acid solution. This silicone-modified polyamic acid solution was diluted with a 6: 4 mixed solvent of NMP and butyl cellosolve so that the resin concentration was 5%, to obtain a liquid crystal aligning agent.

Using this liquid crystal aligning agent, a liquid crystal cell was prepared in the same manner as in Example 1. During rubbing, some scratches were observed, but no peeling was observed. When the display property of the liquid crystal display device produced in the same manner as in Example 1 was confirmed when it was not driven, the orientation was poor and display unevenness was observed.

Comparative Example 2 5- (2,5-dioxotetrahydrofuranyl) -3-methyl in a four-neck separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube. -3-Cyclohexene-1,2-dicarboxylic anhydride 21.14g
(0.08 mol) is dissolved in 250 g of NMP. Then, p-phenylenediamine 8.651 g (0.08 mol) was added all at once, and 20
Stirring was continued for 3 hours while maintaining the temperature at 0 ° C. Toluene in this system
Add 25 g, remove the dry nitrogen gas inlet tube and replace it with a Dean Starch reflux condenser to raise the system temperature. Heating was continued while removing water generated by imidization from the system by azeotropic distillation with toluene, and the reaction was terminated 5 hours after the imidization proceeded at 160 to 170 ° C. and no more water was produced. The resulting polyimide varnish was added dropwise to 30 liters of methanol with stirring for 1 hour to precipitate the polymer, and the solid content was collected by filtration,
It was dried in a dryer at 80 ° C. for 8 hours. 5 parts by weight of this soluble polyimide resin was dissolved in 95 parts by weight of γ-butyrolactone to obtain a liquid crystal aligning agent.

When a liquid crystal cell was produced using this liquid crystal aligning agent in the same manner as in Example 1, peeling of the alignment film was observed during rubbing. When the display property of the liquid crystal display device manufactured in the same manner as in Example 1 was checked when it was not driven, display unevenness due to peeling of the alignment film during rubbing was observed.

Comparative Example 3 A liquid crystal cell was prepared in the same manner as in Example 1 except that the polyamide solution (a) obtained in Synthesis Example 1 was used as a liquid crystal aligning agent. As a result, peeling of the alignment film was observed during rubbing. . When the display property of the liquid crystal display element produced in the same manner as in Example 1 was confirmed when it was not driven, a display defect due to peeling of the alignment film during rubbing was observed.

(Comparative Example 4) A liquid crystal cell was prepared in the same manner as in Example 1 except that the polyamic acid solution (B) obtained in Synthesis Example 8 was used as a liquid crystal aligning agent. No peeling was observed during rubbing. . Furthermore, when the liquid crystal display element produced in the same manner as in Example 1 was confirmed for display characteristics when not driven,
The orientation was poor, and display unevenness was observed.

Comparative Example 5 A polyimide solution was obtained in the same manner as in Comparative Example 2, except that 95 parts by weight of γ-butyrolactone was replaced with 95 parts by weight of NMP. When 50 parts by weight of this polyimide solution and 50 parts by weight of the polyamic acid solution (A) obtained in Synthesis Example 7 were mixed to form a liquid crystal aligning agent, it became cloudy and a uniform solution could not be obtained. When a liquid crystal display device was coated and baked on a substrate in the same manner as in Example 1, a uniform film could not be obtained.

Comparative Example 6 2,2-bis (4- (4-aminophenoxy) phenyl) in a four-necked separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube. 32.84 g (0.08 mol) of propane is dissolved in 200 g of NMP. Subsequently, 17.45 g (0.08 mol) of pyromellitic dianhydride was added all at once, and stirring was continued for 5 hours while maintaining the temperature at 20 ° C. to obtain a polyamic acid solution. A liquid crystal aligning agent was prepared by mixing 50 parts by weight of this polyamic acid solution with 50 parts by weight of the polyamide solution (a) obtained in Synthesis Example 1. When rubbing was performed in the same manner as in Example 1, no scratch or peeling of the alignment film was observed.

Subsequently, a liquid crystal cell was prepared in the same manner as in Example 1, and the pretilt angle was evaluated. The pretilt angle was 7 degrees both before and after standing at 90 ° C. When a liquid crystal display element was produced in the same manner as in Example 1 and the consumption current was evaluated, it was 1.2 μA before being left at 90 ° C. and 3.0 μA after being left at 90 ° C. The display property was good both before driving and after driving at 90 ° C, but after driving at 90 ° C, display defects occurred during driving.

In each of Examples 1 to 9, the rubbing resistance was excellent, the peeling of the alignment film and the display defect due to it did not occur, and the pretilt angle was 4 even though the firing temperature was as low as 120 ° C. The displayability and current consumption of the liquid crystal display element were good, satisfying the values required for STN type LCDs. Further, even after the high temperature storage test of 90 ° C./one week, the deterioration of the performance such as the decrease of the pretilt angle, the decrease of the display property and the increase of the current consumption did not occur, which was good.

In Comparative Example 1, when a liquid crystal aligning agent containing a silicone-modified polyamide as a resin component was used, the firing temperature was low, so that the orientation was poor and good displayability was not obtained.

In Comparative Example 2, when a liquid crystal aligning agent containing a soluble polyimide as a resin component was used, when adhesiveness was insufficient and peeling occurred during rubbing, and a liquid crystal display device was formed, a display defect based on this occurred, which was good. I couldn't get a proper display.

In Comparative Example 3, when a liquid crystal aligning agent containing only a polyamide having an aromatic group as a resin component was used, the adhesiveness was insufficient and peeling occurred during rubbing, so that a display based on this was used. A defect was generated and a good display could not be obtained.

In Comparative Example 4, when a liquid crystal aligning agent containing only a polyamic acid having an aliphatic tetracarboxylic acid structure as a resin component was used, the firing temperature was low, and the orientation was poor and good display properties were obtained. There wasn't.

In Comparative Example 5, when a polyimide solution and a polyamic acid solution were mixed and used, a uniform aligning agent could not be obtained, and even when an alignment film was formed, it was non-uniform and unusable. It was

In Comparative Example 6, since the polyamic acid having the aromatic tetracarboxylic acid structure was used instead of the polyamic acid having the aliphatic tetracarboxylic acid structure, good performance was obtained before the high temperature storage test at 90 ° C./one week. As shown, after the high temperature storage test, there was a problem in reliability due to a large increase in current consumption and defective display during driving.

[0063]

The liquid crystal aligning agent of the present invention exhibits good rubbing resistance even when fired at an extremely low temperature of 120 ° C., and requires color STN-LCDs, color active matrix LCDs, and plastics that require a low process temperature. It is a liquid crystal aligning agent that can be used in the manufacture of panel or plastic film substrate LCD and is especially suitable for the manufacture of plastic substrate STN-LCD. Further, the liquid crystal display device using the present alignment agent is a liquid crystal display device which can realize a high yield in processing at low temperature and is excellent in display property and electric property reliability.

Claims (5)

[Claims] 1. A liquid crystal aligning agent comprising a polyamide having a linear alkyl structure at a molecular end and a polyamic acid having an aliphatic tetracarboxylic acid structure as essential components. 2. The liquid crystal aligning agent according to claim 1, wherein the polyamide is a polyamide having an aliphatic dicarboxylic acid structure. 3. The liquid crystal alignment according to claim 2, wherein the polyamide has a structure represented by the general formula (1) or the general formula (2), and the polyamic acid has a structure represented by the general formula (3). Agent. [Chemical 1] [Chemical 2] [Chemical 3] [Chemical 4] 4. The liquid crystal aligning agent according to claim 3, wherein R ₄ in the general formula (4) is represented by —CH ₂ —. 5. A liquid crystal display device using the liquid crystal aligning agent according to claim 1.