JPH07270803A - Liquid crystal orienting agent and its production - Google Patents

Abstract

PURPOSE:To obtain a high pretilt angle without damaging color filters by using a specific polyamide acid and silicone denatured polyamide acid as resin components and specifying solvent components and the compsn. ratios thereof. CONSTITUTION:The polyamide acid having the aliphat. acid structure expressed by formula I and the silicone denatured polyamide acid expressed by formula II are used as the resin components. The solvent components and the compsn. ratios thereof are specified to 1 to 10wt.% N-methyl-2-pyrrolidone, 20 to 40wt.% butylcellsolve and 50 to 80wt.% ethyl carbitol. In the formulas I, II, R denotes a quadrivalent aliphat. group; Ar1 and Ar3 denote the structure selected from formula III, etc.; Ar2 denotes the structure selected from formula IV, etc.; n, m denote the charging molar ratios at the time of synthesizing the resin components; n:m denote a range of 30:70 to 95:5; k denotes an integer from 1 to 20 and denotes the average repeating number of a siloxane unit. Good uniformity of films when the films are formed on the color filters formed by a dyeing method is obtainable with this liquid crystal orienting agent.

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 particularly to a color filter for use in a liquid crystal display device in which a color filter is formed inside a transparent electrode. The present invention relates to a liquid crystal aligning agent which can be processed at a low temperature and can obtain a high pretilt angle without causing damage such as dissolution and swelling of a liquid crystal, and a method for producing the same.

[0002]

2. Description of the Related Art At present, liquid crystal display devices have been widely used as thin displays. There are various types of liquid crystal display elements depending on the operation mode and driving method.
There is a Super Twisted Nematic (STN) type liquid crystal display element as a method that is low in cost and relatively excellent in display quality, and is widely used for portable word processors and computers. A liquid crystal aligning agent is used in a liquid crystal display device to form an alignment film on a substrate that uniformly aligns liquid crystals inside the liquid crystal display device. An item required for the liquid crystal aligning agent for STN is an alignment direction of liquid crystal molecules. The angle formed by 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 polyimide precursor solutions described in JP-A-62-297819 and JP-A-1-177514.

On the other hand, color display is performed by combining a liquid crystal display element with a color filter. Generally, when a color filter is combined, it is formed on the outside of a transparent electrode substrate sandwiching a liquid crystal, but in recent years, a method of forming the color filter on the inside of the transparent electrode substrate for the purpose of cost reduction of a color liquid crystal display device. Have been put to practical use mainly for TN type liquid crystal display elements. This liquid crystal display element is mainly used in liquid crystal televisions and the like, but there is a strong demand for improvement in display image quality. Therefore, in order to improve the image quality of these low-cost color liquid crystal display elements, ST
Similar methods have been investigated using the N type. However, the following is a problem here.

A liquid crystal alignment film is formed inside the transparent electrode of the liquid crystal display element. When a color filter is formed inside the transparent electrode, the liquid crystal alignment film should be formed on the color filter. Liquid crystal aligning agent containing N-methyl-2-pyrrolidone (NMP) as a main solvent component as described in JP-A-297819 and γ-butyrolactone (GBL) as described in JP-A-61-205924. When a soluble polyimide type liquid crystal aligning agent containing () as a main solvent component is printed, the solvent dissolves the color filter,
It will become unusable due to damage such as swelling or cracking.

On the other hand, in a TN type liquid crystal display element in which a color filter is formed inside a transparent electrode, the following liquid crystal aligning agent is used to solve this problem. That is, to the extent that a polyamic acid composed of an aliphatic tetracarboxylic acid dianhydride and a diamine as disclosed in JP-B-4-33010 is synthesized in ethyl carbitol (ECT) and does not damage the color filter. Butyl cellosolve (BCS) is added and used. But,
JP 62-297819 A and JP 1-1775.
When an aliphatic tetracarboxylic acid dianhydride is used as the tetracarboxylic acid dianhydride in the liquid crystal aligning agent described in JP-A No. 14-2004, the temperature of 4 to 8 degrees required for STN type is required unless firing at 220 to 250 ° C. Since the pretilt angle cannot be exhibited, it cannot be used for the color STN type liquid crystal display device of the above-mentioned method in which the firing temperature is limited to about 180 ° C. due to the heat resistance of the color filter.

[0006]

The present invention solves the problems of the liquid crystal aligning agent as described above, and can process at a low temperature of 180 ° C. or less without damaging the color filter, and can obtain a high pretilt angle. A liquid crystal aligning agent and a method for producing the same are provided.

[0007]

The present invention is based on the general formula (1)
The polyamic acid having an aliphatic acid structure represented by and the silicone-modified polyamic acid represented by the general formula (2) are used as resin components, and the solvent component and the composition ratio thereof are 1 to 10% by weight of N-methyl-2-pyrrolidone. , Butyl cellosolve 20 to 40% by weight, and ethyl carbitol 50 to 80% by weight, and a method for producing the same.

[0008]

[Chemical 1]

[Chemical 2]

(In the formula, R represents a tetravalent aliphatic group, and Ar ₁
And Ar ₃

[Chemical 3] Represents a structure selected from among, and may be the same as or different from each other, Ar ₂ is

[Chemical 4] Represents a structure selected from among. n and m represent a charged molar ratio at the time of synthesizing the resin component, and n: m represents a range of 30:70 to 95: 5. k is a number of 1 or more and 20 or less and represents the average number of repeating siloxane units. )

Further, R in the general formula (1) is

[Chemical 5] And Ar ₂ in the general formula (2) is

[Chemical 6] The liquid crystal aligning agent and the method for producing the same, wherein Ar ₁ in the general formula (1) is

[Chemical 7] And Ar ₃ in the general formula (2) is

[Chemical 8] The above liquid crystal aligning agent and the method for producing the same.

The liquid crystal aligning agent of the present invention comprises a polyamic acid having an aliphatic acid structure represented by the general formula (1), which can be synthesized even in ECT which causes less damage to a color filter than NMP or GBL, and in ECT. Although the synthesis is impossible, after the synthesis, the resin component is a silicone-modified polyamic acid represented by the general formula (2) which is dissolved in this solvent and exhibits a high pretilt angle even at low temperature firing. Therefore, with the present alignment agent as a whole, a uniform solution can be obtained even if the concentration of NMP in the solvent component is 10% by weight or less.

The solvent component of the liquid crystal aligning agent of the present invention and the composition ratio thereof are NMP1 to 10 when the whole solvent is 100%.
% By weight, BCS 20-40% by weight, ECT 50-80% by weight. When NMP exceeds 10% by weight, the color filter is damaged. If NMP is less than 1%, it becomes difficult to synthesize a silicone-modified polyamic acid. BC
S alone has no effect on the color filter at all, and the more it is, the better it is, but if it exceeds 40% by weight, the volatility of the whole solvent becomes too high, and the printability is deteriorated. If it is less than 20% by weight, the color filter is damaged. BCS is 30-35 due to the balance of both characteristics.
More preferably, it is wt%. The most abundant solvent component, ECT, has the ability to dissolve the resin component of the liquid crystal aligning agent of the present invention, and has less influence on the color filter than NMP. If the ECT is less than 50% by weight, the solubility is insufficient and the liquid crystal aligning agent becomes non-uniform, resulting in problems such as clouding or gelation. If it is more than 80% by weight, the color filter is damaged. In the present invention, NMP,
Other solvents can be added within the range of BCS and ECT in the above composition range. NMP, BCS, E
Examples of substances that can be added in addition to CT include GBL, ethyl cellosolve, ethyl cellosolve acetate, butyl cellosolve acetate, phenoxyethanol, methyl carbitol, butyl carbitol, dimethyl diglyme, diethyl diglyme, dibutyl diglyme, dimethyl triglyme, dimethyl. Examples thereof include, but are not limited to, tetraglyme, cyclohexanone, propylene carbonate, toluene and xylene.

The polyamic acid having an aliphatic acid structure represented by the general formula (1) in the present invention is obtained by reacting an aliphatic tetracarboxylic dianhydride with a diamine using ECT as a reaction solvent. As the reaction solvent, NMP, dimethylacetamide, dimethylformamide or the like can be used, but when the reaction is carried out in a solvent other than ECT, the solvent is replaced in order to finally obtain the solvent composition of the present invention. However, it is not preferable because the cost must be increased and the amount of waste increases. Examples of the aliphatic tetracarboxylic dianhydride include butanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, 1,2,4,5-
Cyclohexane tetracarboxylic acid dianhydride, 5- (2,5-
Dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, bicyclo
Examples include [2,2,2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride and 2,4,5-tricarboxycyclopentylacetic acid dianhydride, but are not limited thereto. Not a thing. Furthermore, it is more preferable to use butanetetracarboxylic dianhydride among these aliphatic tetracarboxylic dianhydrides. As the diamine, p-phenylenediamine, 2,5-diamino-p-xylene, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, 1,4-bis (4 -Aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, 2,2-bis [4,4 '-(4-
Aminophenoxy) phenyl] propane, 2,2-bis [4,
4 '-(4-aminophenoxy) phenyl] hexafluoropropane can be used, and among these diamines, 4,4'-
More preferably, diaminodiphenylmethane is used.

The silicone-modified polyamic acid represented by the general formula (2) in the present invention is obtained by reacting an aromatic tetracarboxylic dianhydride with silicone diamine and other diamines using NMP as a reaction solvent. As the aromatic tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride It is possible to use 2,3,6,7-naphthalenetetracarboxylic acid dianhydride, 3,3 ', 4,4'-benzophenonetetracarboxylic acid dianhydride, and use pyromellitic acid dianhydride Is more preferable. As the silicone diamine, 1,3-bis (3-aminopropyl) tetramethyldisiloxane, 1,11-bis (3-aminopropyl) hexa (dimethylsiloxane) or the like can be used. Diamines other than silicone diamine include p-phenylenediamine, 2,5-diamino-p-xylene, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 1,4 -Screw
(4-Aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, 2,2-bis [4,4 '-(4-aminophenoxy) phenyl] propane, 2,2-bis [4 ,
4 '-(4-aminophenoxy) phenyl] hexafluoropropane can be used, and of these diamines, it is more preferable to use 2,2-bis [4,4'-(4-aminophenoxy) phenyl] propane. In the general formula (2), the ratio n: m of the diamine other than the silicone diamine and the silicone diamine is in the range of 30:70 to 95: 5. n is 30
If it is in the smaller range, good orientation cannot be obtained, and if n is in the range of more than 95, the required pretilt angle cannot be exhibited.

[0015]

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

(Example 1) 4,4'-diaminodiphenyl ether 20.0 in a four-neck separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube.
2 g (0.100 mol) are dissolved in 250 g ECT. To this system, 26.42 g (0.100 mol) of 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride was added and dry nitrogen was added. A polyamic acid was synthesized by reacting at 10 to 15 ° C. for 12 hours while flowing. ECT 124.01g to 100g of this solution
And 89.29 g of BCS are added, and the solvent composition is ECT / BCS.
A polyamic acid solution (A) having an aliphatic acid structure with a concentration of 5%, which is 70/30, was obtained. On the other hand, in a four-neck separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube, 26.82 g (0.100 g) of 1,4,5,8-naphthalenetetracarboxylic dianhydride was prepared. Mol) to NMP 13
Disperse in 1.8 g and bring the system temperature to 0-5 ° C. A dropping funnel was attached to the raw material inlet, and 1,3-bis (3-aminopropyl) tetramethyldisiloxane 14.91 g (0.0)
(60 mol) was added dropwise under a dry nitrogen inflow over 1 hour, and after the addition, stirring was continued at 0 to 5 ° C. for 2 hours. The dropping funnel was removed from the raw material charging port, and 14.74 g (0.040 mol) of 4,4'-bis (4-aminophenoxy) biphenyl was charged and the reaction was continued for another 5 hours. A silicone-modified polyamic acid was synthesized by reacting at 10 to 15 ° C. for 12 hours. 100 g of this solution contains 329.0 g of ECT and 171.0 g of BCS.
And the solvent composition is NMP / ECT / BCS = 12/58
A silicone-modified polyamic acid solution (B) with a concentration of 5/30 was obtained. A polyamic acid solution (A) having an aliphatic acid structure (50.0 g) and a silicone-modified polyamic acid solution (B) (50.0 g) were sufficiently mixed to obtain a solvent composition of NMP / E.
A liquid crystal aligning agent having CT / BCS = 6/64/30 was obtained.

This liquid crystal aligning agent was printed on a substrate having a color filter formed on a transparent electrode by a dyeing method, prebaked in an oven at 80 ° C. for 5 minutes, and then baked at 165 ° C. for 1 hour. When observed with the naked eye, there was no printing unevenness and a uniform film was formed. When observed with a microscope, no damage such as cracks was found on the color filter. An alignment film was similarly formed on a transparent glass substrate, rubbing was performed, and then an antiparallel cell having a cell gap of 50 μm was produced. Liquid crystal is Merck ZLI-
2293 was injected. The pretilt angle measured by the crystal rotation method was 5.0 degrees.

(Example 2) 4,4'-diaminodiphenylmethane 19.83 in a four-neck separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube.
g (0.100 mol) is dissolved in 250 g of ECT.
In this system, butane tetracarboxylic dianhydride 19.81
g (0.100 mol) was added and dry nitrogen was infused for 10 to 15
A polyamic acid was synthesized by reacting at 12 ° C. for 12 hours. To 100 g of this solution, 53.12 g of ECT and 75.08 g of BCS were added to obtain a polyamic acid solution (C) having a solvent composition of ECT / BCS = 65/35 and a concentration of 6% and having an aliphatic acid structure. On the other hand, in a four-neck separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet pipe, 21.81 g (0.100 mol) of pyromellitic dianhydride was NMP.
Disperse in 127.8 g and bring the system temperature to 0-5 ° C.
Attaching a dropping funnel to the raw material inlet, 1,3-bis (3-aminopropyl) tetramethyldisiloxane 12.43g
(0.050 mol) was added dropwise under a dry nitrogen flow over 1 hour, and after the addition, stirring was continued at 0 to 5 ° C for 2 hours. Remove the dropping funnel from the raw material inlet 2,2-bis [4,4'-
(4-Aminophenoxy) phenyl] propane 20.53g
(0.050 mol) was added and the reaction was continued for another 5 hours. A silicone-modified polyamic acid was synthesized by reacting at 10 to 15 ° C. for 12 hours. ECT 23 was added to 100 g of this solution.
5.5g and BCS 164.5g are added and the solvent composition is NMP.
A silicone-modified polyamic acid solution (D) having a concentration of / ECT / BCS = 15/50/35 and a concentration of 6% was obtained. The polyamic acid solution (C) having an aliphatic acid structure (C) (80.0 g) and the silicone-modified polyamic acid solution (D) (20.0 g) were sufficiently mixed to have a solvent composition of NMP / ECT / BCS = 3/62 /
A liquid crystal aligning agent of 35 was obtained.

This liquid crystal aligning agent was printed on a substrate having a color filter formed on a transparent electrode by a dyeing method, prebaked in an oven at 80 ° C. for 5 minutes, and then baked at 180 ° C. for 1 hour. When observed with the naked eye, there was no printing unevenness and a uniform film was formed. When observed with a microscope, no damage such as cracks was found on the color filter. An alignment film was similarly formed on a transparent glass substrate, rubbing was performed, and then an antiparallel cell having a cell gap of 50 μm was produced. Liquid crystal is Merck ZLI-
2293 was injected. The pretilt angle measured by the crystal rotation method was 8.0 degrees.

(Example 3) 2,2-bis [4,4 '-(4-aminophenoxy) in a four-necked separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube. ) Phenyl] propane 41.05 g (0.100 mol) ECT
Dissolve in 250 g. 19.81 g (0.100 mol) of butanetetracarboxylic dianhydride was added to this system and reacted at 10 to 15 ° C. for 12 hours under a dry nitrogen flow to synthesize a polyamic acid. ECT 118. was added to 100 g of this solution.
9g and BCS 107.4g are added and the solvent composition is ECT / B
A polyamic acid solution (E) having a 6% concentration of CS = 65/35 and having an aliphatic acid structure was obtained. On the other hand, in a four-neck separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube, pyromellitic dianhydride 21.8
1 g (0.100 mol) is dispersed in 137.1 g NMP and the temperature of the system is brought to 0-5 ° C. A dropping funnel was attached to the raw material charging port, and 7,456 g (0.030 mol) of 1,3-bis (3-aminopropyl) tetramethyldisiloxane was added dropwise over 1 hour while inflowing dry nitrogen, and further 0 to 5 after the addition. Continue stirring at 0 ° C for 2 hours. The dropping funnel was removed from the raw material charging port, and 4,4'-diaminodiphenyl ether 14.02g
(0.070 mol) was added and the reaction was continued for another 5 hours. A silicone-modified polyamic acid was synthesized by reacting at 10 to 15 ° C. for 12 hours. ECT 16 was added to 100 g of this solution.
8.4g and BCS 131.6g are added and the solvent composition is NMP.
A silicone modified polyamic acid solution (F) having a concentration of / ECT / BCS = 19/46/35 and a concentration of 6% was obtained. The polyamic acid solution (E) having an aliphatic acid structure (E) (80.0 g) and the silicone-modified polyamic acid solution (F) (20.0 g) were sufficiently mixed to have a solvent composition of NMP / ECT / BCS = 4.8 / 6.
A liquid crystal aligning agent having a ratio of 0.2 / 35 was obtained.

This liquid crystal aligning agent was printed on a substrate having a color filter formed on a transparent electrode by a dyeing method, prebaked in an oven at 80 ° C. for 5 minutes, and then baked at 150 ° C. for 2 hours. When observed with the naked eye, there was no printing unevenness and a uniform film was formed. When observed with a microscope, no damage such as cracks was found on the color filter. An alignment film was similarly formed on a transparent glass substrate, rubbing was performed, and then an antiparallel cell having a cell gap of 50 μm was produced. Liquid crystal is Merck ZLI-
2293 was injected. The pretilt angle measured by the crystal rotation method was 4.0 degrees.

(Examples 4 to 9) Example 3 was repeated except that the raw material acid dianhydride and diamine, the mixing ratio of the polyamic acid having an aliphatic acid structure and the silicone-modified polyamic acid, and the solvent composition ratio were changed. In the same manner as described above, printing unevenness, color filter damage, and pretilt angle were evaluated, and the results in Table 1 were obtained.

[0023]

[Table 1]

(Abbreviations in Table) BTA; butanetetracarboxylic dianhydride DDS; 4,4'-diaminodiphenylsulfone G1; 1,3-bis (aminopropyl) tetramethyldisiloxane (in the general formula (2) Which gives k = 1) 1,4-APB; 1,4-bis (aminophenoxy) benzene FMCDA; 5- (2,5-dioxotetrahydro-3-furanyl) -3-methyl-3-cyclohexene- 1,2-dicarboxylic acid anhydride 2,5-DPX; 2,5-diamino-p-xylene BTDA; 3,3 ', 4,4'-benzophenone tetracarboxylic acid dianhydride G5; bis (aminopropyl) poly (Dimethylsiloxane) giving k = 5 in the general formula (2) BAPB; 4,4′-bis (4-aminophenoxy) biphenyl CBTA; cyclobutanetetracarboxylic dianhydride DDE; 4,4′-diaminodiphe Nyl ether NTDA; 2,3,6,7-naphthalenetetracarboxylic dianhydride G9; Bis (aminopropyl) poly (dimethylsiloxane) that gives k = 9 in the general formula (2) BOEDA; Bicyclo [2, 2,2] Oct-7-En-2,
3,5,6-Tetracarboxylic dianhydride PPD; p-Phenylenediamine BPDA; 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride HFBAPP; 2,2-bis [4,4'- (4-Aminophenoxy) phenyl] hexafluoropropane CPTA; 1,2,3,4-cyclopentanetetracarboxylic dianhydride PMDA; pyromellitic dianhydride CHTA; 1,2,4,5-cyclohexanetetracarboxylic Acid dianhydride BAPP; 2,2-bis [4,4 '-(4-aminophenoxy) phenyl] propane

(Comparative Example 1) The silicone-modified polyamic acid solution (D) having a solvent composition of NMP / ECT / BCS = 15/50/35 and a concentration of 6% in Example 2 was used alone as a liquid crystal aligning agent. This liquid crystal aligning agent was printed on a substrate having a color filter formed by a dyeing method on a transparent electrode, prebaked in an oven at 80 ° C for 5 minutes, and then 180 ° C.
Firing was performed for 1 hour. When observed with the naked eye, there was no printing unevenness and a uniform film was formed. When observed under a microscope, many cracks were seen on the color filter and discoloration had occurred, which gave irreversible damage to the color filter.

(Comparative Example 2) In Example 2, the polyamic acid solution (C) having an aliphatic acid structure having a solvent composition of ECT / BCS = 65/35 and a concentration of 6% was used alone as a liquid crystal aligning agent. This liquid crystal aligning agent was printed on a substrate having a color filter formed on a transparent electrode by a dyeing method, prebaked in an oven at 80 ° C. for 5 minutes, and then baked at 150 ° C. for 2 hours. When observed with the naked eye, there was no printing unevenness and a uniform film was formed. When observed under a microscope,
No damage such as cracks was found on the color filter. An alignment film was similarly formed on a transparent glass substrate, rubbing was performed, and then an antiparallel cell having a cell gap of 50 μm was produced. Liquid crystal is ZLI-2 made by Merck
293 was injected. The pretilt angle measured by the crystal rotation method was 0.8 degree.

(Comparative Example 3) In Example 2, the concentration was 6%.
The amount of ECT and BCS added when obtaining the polyamic acid solution (C) having an aliphatic acid structure of is changed from 53.12 g to 31.67 g and 75.08 g to 96.53 g, respectively, and the solvent composition is changed to ECT / BCS = A polyamic acid solution (C ′) having an aliphatic acid structure of 55/45 was obtained. Further, the amounts of ECT and BCS added when obtaining the silicone-modified polyamic acid solution (D) were 235.5 g to 188.
A silicone-modified polyamic acid solution (D ′) having a solvent composition of NMP / ECT / BCS = 15/40/45 was obtained in place of 5 g, 164.5 g to 211.5 g. Sufficiently mixing 80.0 g of polyamic acid solution (C ') having an aliphatic acid structure and 20.0 g of silicone-modified polyamic acid solution (D') to obtain a solvent composition of NMP / ECT / BCS = 3/52/4.
A liquid crystal aligning agent of No. 5 was obtained. This liquid crystal aligning agent was printed on a substrate having a color filter formed on a transparent electrode by a dyeing method, prebaked in an oven at 80 ° C. for 5 minutes, and then 1
Firing was performed at 80 ° C. for 1 hour. When observed under a microscope, no damage such as cracks was found on the color filter, but when the film was observed with the naked eye, the film thickness was uneven and a uniform film was not formed.

With respect to the liquid crystal aligning agents produced in Examples 1 to 9, the uniformity of the coating film when printed on the substrate having the color filter formed by the dyeing method was good and the color filter was damaged. Absent. In addition, the pretilt angle is 4 to 8 degrees, and ST
It can be used for N-type liquid crystal display elements.

In Comparative Example 1, since the amount of NMP in the solvent was too much, the color filter was damaged.

In Comparative Example 2, the uniformity of the coating film when printed on a substrate having a color filter formed by a dyeing method was good and did not damage the color filter, but the pretilt angle was as low as 0.8 degree. , STN type liquid crystal display devices cannot be used.

In Comparative Example 3, although the color filter was not damaged, the BCS in the solvent was too much and the film thickness of the coating became non-uniform.

[0032]

The liquid crystal aligning agent and the method for producing the same according to the present invention, when a film is formed on a color filter formed by a dyeing method, good film uniformity can be obtained and the color filter is not damaged. Further, the present invention provides a liquid crystal aligning agent which can be processed at a low temperature of 180 ° C. or lower to avoid thermal deterioration of a color filter and can obtain a high pretilt angle required for STN type liquid crystal display elements.

Claims (6)

[Claims] 1. A polyamic acid having an aliphatic acid structure represented by the general formula (1) and a silicone-modified polyamic acid represented by the general formula (2) are used as resin components, and a solvent component and its composition ratio are N. -Methyl-2-pyrrolidone 1-10% by weight, butyl cellosolve 20-40% by weight, ethyl carbitol 5
Liquid crystal aligning agent of 0 to 80% by weight. [Chemical 1] [Chemical 2] (In the formula, R represents a tetravalent aliphatic group, and Ar ₁ and Ar ₃ are Represents a structure selected from among and may be the same or different, and Ar ₂ is Represents a structure selected from among. n and m represent a charged molar ratio at the time of synthesizing the resin component, and n: m represents a range of 30:70 to 95: 5. k is a number of 1 or more and 20 or less and represents the average number of repeating siloxane units. ) 2. R in the general formula (1) is And Ar ₂ in the general formula (2) is The liquid crystal aligning agent according to claim 1, wherein 3. Ar ₁ in the general formula (1) is represented by: And Ar ₃ in the general formula (2) is The liquid crystal aligning agent according to claim 1 or 2, wherein 4. The method for producing a liquid crystal aligning agent according to claim 1. 5. The method for producing a liquid crystal aligning agent according to claim 2. 6. The method for producing a liquid crystal aligning agent according to claim 3.