JPH09127512A - Liquid crystal orienting agent and liquid crystal display element formed by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an orienting agent yielding an oriented film which exhibits stable liquid crystal orientability and pretilt angle without depending on the processing conditions in assembly of the liquid crystal display element and use environment and exhibits stable electro-optical characteristics by incorporating polyamide and polyamide acid which are respectively specific into the agent. SOLUTION: This orienting agent contains the polyamide essentially consisting of aliphatic dicarboxylic acid, the polyamide acid essentially consisting of arom. tetracarboxylic dianhydride and the polyamide acid essentially consisting of aliphat. tetracarboxylic dianhydride. The polyamide essentially consisting of the aliphat. dicarboxylic acid exhibits particularly the excellent characteristics as the liquid crystal oriented film when the compd. expressed by the formula is used. such aliphat. dicarboxylic acids are usable alone or in combination of >=2 kinds. In the formula, (n) denotes as integer from 2 to 16.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid crystal aligning agent. More specifically, the present invention relates to a liquid crystal aligning agent that can be preferably used to provide a liquid crystal alignment film of a liquid crystal display device of a TN system, an STN system, or a ferroelectric liquid crystal system, and a liquid crystal display device using the same. More specifically, the present invention relates to a liquid crystal aligning agent capable of arbitrarily controlling various characteristics required in various liquid crystal display elements and a liquid crystal display element using the same.

[0002]

2. Description of the Related Art Conventionally, there has been known a method of using an organic polymer film such as polyvinyl alcohol, polyamide resin, polyamide imide resin, and polyimide resin as an alignment film of a liquid crystal display. Of these, polyimide resins and polyamide resins are widely used as liquid crystal alignment films because they have the function of aligning various liquid crystals and are relatively excellent in heat resistance and the like. However, as the characteristics of liquid crystal displays have been improved in recent years, the characteristics of the alignment film material have been required to be better than ever. Specifically, in terms of liquid crystal alignment film properties, excellent liquid crystal alignment under various conditions and stable pre-tilt angle (range of 1 to 20 degrees) required in each method under various conditions In addition, the film has excellent electro-optical characteristics, and in the process, uniform film forming property, rubbing resistance, baking at low temperature, and the like can be mentioned. In particular, in order to shorten the product cycle time, improve the product yield, and prevent thermal damage to various peripheral materials in the process, lower the firing temperature of the aligning agent and each step while maintaining the above various alignment film characteristics. It is hoped that the process margin will be expanded. Conventional liquid crystal aligning agents include aromatic polyamic acid, aliphatic polyamic acid, aliphatic soluble polyimide, aromatic polyamide, and aliphatic polyamide. Of these, aromatic polyamic acid-based aligning agents generally have poor electrical characteristics as a liquid crystal display element,
Further, the aliphatic polyamic acid-based aligning agent is inferior in the liquid crystal aligning property, and a high firing temperature is required to obtain a liquid crystal aligning property and a stable pretilt angle to some extent. Further, since the aliphatic soluble polyimide-based material has poor adhesion to the substrate, there is a problem that the coating film is easily peeled off by rubbing. In addition, although polyamide-based aligning agents can be fired at low temperatures, aromatic polyamides generally have poor electrical characteristics as liquid crystal display elements, and aliphatic polyamides generally have low pretilt angles, similar to aromatic polyamic acids. Even the one that gives a relatively high pretilt angle has a problem in its stability. As described above, the polyimide-based or polyamide-based liquid crystal aligning agents currently used cannot be said to sufficiently meet various requirements, and more excellent liquid crystal alignment film materials are required.

[0003]

DISCLOSURE OF THE INVENTION The present invention shows stable liquid crystal alignment and pretilt angle irrespective of the process conditions for assembling a liquid crystal display element and the use environment, as compared with the conventional liquid crystal alignment film materials, and has a good electro-optical property. A liquid crystal aligning agent that gives a liquid crystal aligning film exhibiting characteristics and a liquid crystal display device using the same.

[0004]

The present invention is directed to a polyamide containing an aliphatic dicarboxylic acid as an essential component, a polyamic acid containing an aromatic tetracarboxylic acid dianhydride as an essential component, and an aliphatic tetracarboxylic acid dianhydride. It is a liquid crystal aligning agent characterized by containing a polyamic acid as an essential component.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Polyamides containing an aliphatic dicarboxylic acid as an essential component used in the present invention, and polyamic acids containing an aromatic tetracarboxylic dianhydride as an essential component,
And for the polyamic acid having an aliphatic tetracarboxylic acid dianhydride as an essential component, the constituent raw materials are not particularly limited, but in a polyamide having an aliphatic dicarboxylic acid as an essential component, the following as an aliphatic dicarboxylic acid: When the compound shown in 1 is used, it exhibits particularly excellent properties as a liquid crystal alignment film. These aliphatic dicarboxylic acids can be used alone or in combination of two or more.

[0006]

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Further, in a polyamic acid containing an aromatic tetracarboxylic dianhydride as an essential component, particularly excellent characteristics as a liquid crystal alignment film are obtained when the aromatic tetracarboxylic dianhydride is a compound shown below. Show. These aromatic tetracarboxylic dianhydrides can be used alone or in combination of two or more.

[0008]

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Further, in a polyamic acid containing an aliphatic tetracarboxylic acid dianhydride as an essential component, when the aliphatic tetracarboxylic acid dianhydride is a compound shown below, particularly excellent properties as a liquid crystal alignment film are obtained. Show. These aliphatic tetracarboxylic dianhydrides can be used alone or in combination of two or more.

[0010]

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On the other hand, in the polyamic acid containing an aromatic tetracarboxylic dianhydride as an essential component and the polyamic acid containing an aliphatic tetracarboxylic dianhydride as an essential component,
The diamine component is not particularly limited,
For example, paraphenylenediamine, metaphenylenediamine, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl Sulfide, 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, bis (4- (4-aminophenoxy) Phenyl) sulfone, 4,4 '
-Diaminobenzoanilide, bis (4- (4-aminophenoxy) phenyl) hexafluoropropane, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 3,3'-diaminobenzophenone, 3,4'-diamino Benzophenone, 4,4'-diaminobenzophenone, aromatic compounds such as 2,4-diaminotoluene, or 4,4'-diaminodicyclohexylmethane, 1,4-diaminocyclohexane, and fats such as silicone diamine represented by the following formula Group compounds,
These can be used alone or in combination of two or more.

[0012]

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The polyamide of the present invention containing an aliphatic dicarboxylic acid as an essential component, the polyamic acid containing an aromatic tetracarboxylic dianhydride as an essential component, and the polyamide acid containing an aliphatic tetracarboxylic dianhydride as an essential component are synthesized. To this end, a known method can be applied, and the various conditions are not particularly limited, but the following method is generally performed. First, in a polyamide containing an aliphatic dicarboxylic acid as an essential component, when the raw materials are dicarboxylic acid and diamine, N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), N, N-dimethyl In a mixed solvent system of acetamide (DMAc) and pyridine, an inorganic salt such as triphenyl phosphite and lithium chloride is allowed to coexist and reacted at a temperature of about 80 to 150 ° C. to synthesize a polyamide. When an acid halide such as dicarboxylic acid dichloride is used as the raw material for dicarboxylic acid, it is allowed to react with a diamine compound in the presence of triethylamine or pyridine in a solvent such as NMP or DMAc to synthesize a polyamide. The concentration of the reaction solution is preferably between 1 and 40%.

On the other hand, in order to synthesize a polyamic acid containing an aromatic tetracarboxylic dianhydride as an essential component and a polyamic acid containing an aliphatic tetracarboxylic dianhydride as an essential component, N-methyl- 2-pyrrolidone (NMP),
N, N-Dimethylformamide (DMF), N, N-Diaminoacetamide (DMAc), Dimethyl sulfoxide (DMSO), γ
-Butyrolactone (GBL), diglyme, tetraglyme, ethyl carbitol, phenoxyethanol, butyl cellosolve, ethyl cellosolve, m-cresol, xylene, toluene, etc. are used alone or in a mixture of two or more, and a diamine compound and a tetracarboxylic acid are used. Dianhydride
Reacts at temperatures between 0 ° C and 100 ° C. The concentration of the reaction solution is preferably between 1 and 40%.

In preparing a liquid crystal aligning agent, a polyamide containing an aliphatic dicarboxylic acid obtained by the above-mentioned method as an essential component, a polyamic acid containing an aromatic tetracarboxylic dianhydride as an essential component, an aliphatic Polyamic acid containing tetracarboxylic dianhydride as an essential component is mixed in a predetermined ratio according to the required characteristics as a liquid crystal alignment film. At that time, the required liquid crystal alignment characteristics (including pretilt angle), electro-optic The mixing ratio of each component is arbitrarily changed in order to bring out the characteristics and the like. Therefore, the mixing ratio of each component is not particularly specified.

The point of the present invention is that it is difficult for the conventional liquid crystal aligning agent to satisfy all the various requirements required for a liquid crystal display device. Therefore, a polyamide or an aromatic tetracarboxylic acid containing an aliphatic dicarboxylic acid as an essential component is required. Polyamide acid having carboxylic acid dianhydride as an essential component and polyamic acid having aliphatic tetracarboxylic acid dianhydride as an essential component are compounded to form respective features in a complementary manner, As a result, the composite alignment film as a whole satisfies a plurality of characteristics. The liquid crystal alignment film obtained by using the liquid crystal aligning agent of the present invention can be formed, for example, by the following method. First, the liquid crystal aligning agent of the present invention is applied to the transparent conductive film side of a substrate such as glass or plastic provided with a transparent conductive film by a method such as a roll coater method, a spinner method, or a printing method.
Bake at a temperature of ℃ to 300 ℃ to form a coating film. Thereafter, a rubbing treatment is performed to form a liquid crystal alignment film.

By using the liquid crystal aligning agent of the present invention,
In the manufacturing process of the liquid crystal display element, the coating film has good uniformity and excellent adhesion to the substrate, so that there is no trouble such as peeling even in the step of rubbing or the like. Further, in terms of the characteristics of the liquid crystal display element, the alignment property of the liquid crystal and the stability of the pretilt angle reflect the good characteristics of the polyamic acid containing an aromatic tetracarboxylic dianhydride as an essential component, and the electro-optical characteristics of the element are shown. In the above, the liquid crystal aligning agent of the present invention provides an unprecedented excellent liquid crystal aligning film, because the liquid crystal aligning agent of the present invention reflects the good characteristics of the polyamide containing an aliphatic dicarboxylic acid as an essential component.

[0018]

The present invention will now be described in detail with reference to Examples.
The present invention is not limited by these examples.

(Synthesis example 1) 500 ml equipped with a thermometer, a stirrer, a raw material charging port, a reflux condenser and a dry nitrogen gas inlet
In a four-neck separable flask, 13.78 g of 1,4-cyclohexanedicarboxylic acid, 32.84 g of 2,2-bis (4- (4-aminophenoxy) phenyl) propane, 49.65 g of triphenyl phosphite, 17.8 g of lithium chloride. , NMP200g, Pyridine 1
50 g was added and the reaction was carried out at 100 ° C. for 3 hours to obtain a viscous solution. After reprecipitating this solution in methanol, the polymer was isolated and further reprecipitated in pure water 3 times to perform sufficient drying.

(Synthesis Example 2) 1,4-cyclohexanedicarboxylic acid 1 was used as a dicarboxylic acid under the same reaction conditions as in Synthesis Example 1.
3.78 g, diaminodiphenylmethane as a diamine raw material
A polyamide was synthesized using 15.86 g.

(Synthesis Example 3) 1,4-cyclohexanedicarboxylic acid 1 as a dicarboxylic acid under the same reaction conditions as in Synthesis Example 1
A polyamide was synthesized using 3.78 g and 41.48 g of 2,2-bis (4-(-aminophenoxy) phenyl) hexafluoropropane as a diamine raw material.

(Synthesis Example 4) 1,4-cyclohexanedicarboxylic acid 1 as dicarboxylic acid under the same reaction conditions as in Synthesis Example 1
A polyamide was synthesized using 3.78 g and 4,02'-diaminodiphenyl ether 16.02 g as a diamine raw material.

(Synthesis Example 5) Under the same reaction conditions as in Synthesis Example 1, 9.45 g of succinic acid as a dicarboxylic acid and 15.86 g of diaminodiphenylmethane as a raw material of a diamine were used to synthesize a polyamide.

Synthesis Example 6 Under the same reaction conditions as in Synthesis Example 1, 9.45 g of succinic acid as a dicarboxylic acid and 2,2-bis (4- (4-aminophenoxy) phenyl) as a diamine raw material
A polyamide was synthesized using 32.84 g of propane.

(Synthesis Example 7) Under the same reaction conditions as in Synthesis Example 1, a polyamide was synthesized using 11.69 g of adipic acid as a dicarboxylic acid and 15.86 g of diaminodiphenylmethane as a raw material of a diamine.

(Synthesis Example 8) Under the same reaction conditions as in Synthesis Example 1, 11.69 g of adipic acid as a dicarboxylic acid and 32.84 g of 2,2-bis (4- (4-aminophenoxy) phenyl) propane as a diamine raw material were prepared. The polyamide used was synthesized.

(Synthesis Example 9) 1,4-cyclohexanedicarboxylic acid as a dicarboxylic acid under the same reaction conditions as in Synthesis Example 1.
A polyamide was synthesized by using 89 g of terephthalic acid 6.64 g and 15.86 g of diaminodiphenylmethane as a diamine raw material.

(Synthesis Example 10) 1,4-cyclohexanedicarboxylic acid was used as the dicarboxylic acid under the same reaction conditions as in Synthesis Example 1.
6.89 g terephthalic acid 6.64 g, diamine raw material 2,2-
A polyamide was synthesized using 41.48 g of bis (4- (4-aminophenoxy) phenyl) hexafluoropropane.

(Synthesis Example 11) 21.81 g of pyromellitic dianhydride and dehydrated NMP250 were placed in a 500 ml four-neck separable flask equipped with a thermometer, a stirrer, a raw material inlet and a nitrogen gas inlet.
g was added and the mixture was stirred under a stream of dry nitrogen. Set the temperature of the reaction system to 20
While maintaining at ℃, add 9.94 g of bisaminopropyltetramethyldisiloxane, and then add 2,2-bis (4-
(4-Aminophenoxy) phenyl) propane (24.63 g) was added and the mixture was reacted for 5 hours with stirring to obtain a pale yellow viscous solution.

(Synthesis example 12) 21.81 g of pyromellitic dianhydride was used as a raw material by the same apparatus and reaction method as in synthesis example 13.
Bisaminopropyl tetramethyldisiloxane 9.94 g,
A pale yellow viscous solution was obtained using 12.01 g of 4,4'-diaminodiphenyl ether.

(Synthesis Example 13) 21.81 g of pyromellitic dianhydride was used as a raw material by the same apparatus and reaction method as in Synthesis Example 13.
Bisaminopropyl tetramethyldisiloxane 9.94 g,
A pale yellow viscous solution was obtained using 31.11 g of 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane.

(Synthesis Example 14) 21.81 g of pyromellitic dianhydride was used as a raw material by the same apparatus and reaction method as in Synthesis Example 13.
Bisaminopropyl tetramethyldisiloxane 9.94 g,
A pale yellow viscous solution was obtained using 11.90 g of diaminodiphenylmethane.

(Synthesis Example 15) 4,300 g of 4,4'-diaminodiphenylmethane and 150 g of dehydrated NMP were placed in a 300 ml four-neck separable flask equipped with a thermometer, a stirrer, a raw material inlet and a nitrogen gas inlet, and a dry nitrogen stream was introduced. It was stirred under. While maintaining the temperature of the reaction system at 20 ° C., 19.81 g of butanetetracarboxylic dianhydride was added, and the mixture was stirred and reacted for 5 hours to obtain a pale yellow viscous solution.

(Synthesis Example 16) 4,4'-diaminodiphenylmethane 1 was used as a raw material by the same apparatus and reaction method as in Synthesis Example 15.
9.83g, 5- (2,5-dioxotetrahydro-3-furanyl) -3
-Methyl-3-cyclohexene-1,2-dicarboxylic acid dianhydride 2
A pale yellow viscous solution was obtained using 6.42 g.

(Synthesis Example 17) Using the same apparatus and reaction method as in Synthesis Example 15, using 10.81 g of p-phenylenediamine and 19.81 g of butanetetracarboxylic dianhydride as starting materials, a pale yellow viscous solution was obtained. .

Synthesis Example 18 Using the same apparatus and reaction method as in Synthesis Example 15, p-phenylenediamine 10.81 g, 5-
(2,5-dioxotetrahydro-3-furanyl) -3-methyl-3
A pale yellow viscous solution was obtained using 26.42 g of -cyclohexene-1,2-dicarboxylic acid dianhydride.

(Synthesis example 19) 4,4'-diaminodiphenyl ether as a raw material 20.02 g, cyclobutanetetracarboxylic dianhydride 19.6 as a raw material by the same apparatus and reaction method as in synthesis example 15
A pale yellow viscous solution was obtained using 1 g.

(Synthesis Example 20) 4,4'-diaminodiphenylmethane 1 was used as a raw material by the same apparatus and reaction method as in Synthesis Example 15.
9.83 g, cyclobutane tetracarboxylic dianhydride 19.61 g
Was used to obtain a pale yellow viscous solution.

Example 1 The polyamide containing the aliphatic dicarboxylic acid obtained in Synthesis Example 1 as an essential component was dissolved in NMP,
Further, a polyamic acid containing the aromatic tetracarboxylic dianhydride obtained in Synthesis Example 11 as an essential component and a polyamic acid containing the aliphatic tetracarboxylic acid dianhydride obtained in Synthesis Example 15 as an essential component are respectively resin. 20:30:50 by weight ratio of minutes
To obtain a total resin content of 6
%, NMP was added, and the mixture was filtered through a membrane filter having a pore size of 0.5 micron to obtain a liquid crystal aligning agent. This liquid crystal aligning agent is applied to the transparent electrode surface of the glass substrate with a transparent electrode by a spinner and baked at 180 ° C. for 1 hour,
A coating film of about 600 Å was formed. Subsequently, the coating film surface was rubbed by a rubbing machine, two substrates were bonded together with a gap of 5 μm, and a liquid crystal (ZLI-5081 manufactured by Merck) was injected to prepare a TN liquid crystal cell. When the orientation of the liquid crystal was evaluated by a microscope, it was uniform over the entire surface, and the orientation of the liquid crystal was not disturbed at all even after the treatment at 120 ° C. for 500 hours. Moreover, the voltage holding ratio was evaluated as 98.7% as the electrical characteristics of the cell, and it was 97.5% even after the treatment at 120 ° C. for 500 hours. Further, the evaluation of the pretilt angle by the anti-parallel cell was 3.5 degrees, and it was 3.6 degrees after the treatment at 120 ° C. for 50 hours.

(Example 2-20) A polyamide containing the aliphatic dicarboxylic acid obtained in Synthesis Examples 1 to 10 as an essential component,
Polyamic acid having an aromatic tetracarboxylic acid dianhydride obtained in Synthesis Examples 11 to 14 as an essential component, and polyamic acid having an aliphatic tetracarboxylic acid dianhydride obtained in Synthesis Examples 15 to 20 as an essential component Liquid crystal cells were prepared and evaluated in the same manner as in Example 1 by changing the combination and mixing ratio. The liquid crystal alignment was good before and after the treatment at 120 ° C. for 500 hours. Other results are shown in Table 1.

[0041]

[Table 1] The mixing ratio in the table is a polyamide having an aliphatic dicarboxylic acid as an essential component, a polyamic acid having an aromatic tetracarboxylic acid dianhydride as an essential component, and a polyamic acid having an aliphatic tetracarboxylic acid dianhydride as an essential component. Weight ratio. Further, the heat treatments for the items of pretilt angle and voltage holding ratio are after 120 ° C./500 hours.

(Comparative Example 1) Example 1 was prepared using only the polyamide containing the aliphatic dicarboxylic acid obtained in Synthesis Example 2 as an essential component.
When a liquid crystal cell was prepared in the same manner as described in 1., the alignment uniformity of the liquid crystal was good, but the pretilt angle was as low as 1.1 degrees.

Comparative Example 2 A liquid crystal cell was prepared in the same manner as in Example 1 using only the polyamic acid containing the aliphatic dicarboxylic acid dianhydride obtained in Synthesis Example 15 as an essential component. Was good, but the pretilt angle was as low as 1.1 degrees.

Comparative Example 3 A liquid crystal cell was prepared in the same manner as in Example 1 using only the polyamic acid containing the aromatic tetracarboxylic dianhydride obtained in Synthesis Example 12 as an essential component.
The orientation of the liquid crystal was uniform over the entire surface, and the orientation of the liquid crystal was not disturbed at all even after treatment at 120 ° C. for 500 hours. However, when the voltage holding ratio was evaluated, it showed a relatively high value of 97.2% before the heat treatment, but it was 9% after the treatment at 120 ° C for 5 hours.
It had dropped to 1.5%.

[0045]

The liquid crystal aligning agent of the present invention has excellent properties as a liquid crystal aligning film, and is therefore suitably used for various liquid crystal display devices.

Claims (5)

[Claims] 1. A polyamide containing an aliphatic dicarboxylic acid as an essential component, a polyamic acid containing an aromatic tetracarboxylic dianhydride as an essential component, and a polyamide acid containing an aliphatic tetracarboxylic dianhydride as an essential component. A liquid crystal aligning agent characterized by containing. 2. The liquid crystal aligning agent according to claim 1, wherein in the polyamide containing an aliphatic dicarboxylic acid as an essential component, the aliphatic dicarboxylic acid is selected from the compounds shown below. Embedded image 3. The liquid crystal according to claim 1, wherein in the polyamic acid containing an aromatic tetracarboxylic dianhydride as an essential component, the aromatic tetracarboxylic dianhydride is selected from the compounds shown below. Alignment agent. Embedded image 4. The liquid crystal according to claim 1, wherein in the polyamic acid containing an aliphatic tetracarboxylic dianhydride as an essential component, the aliphatic tetracarboxylic dianhydride is selected from the compounds shown below. Alignment agent. Embedded image 5. A liquid crystal display device using the liquid crystal aligning agent according to any one of claims 1 to 4.