JPH05247208A - Coating fluid for oriented liquid-crystal film and production thereof - Google Patents

Abstract

PURPOSE:To obtain an oriented liquid-crystal film having excellent storage stability by using a solution in an organic solvent of a poly(amic acid amide) having a specific molecular structure serving as a polyimide precursor. CONSTITUTION:The title fluid consists mainly of an organic solvent and a poly(amic acid amide) having repeating units represented by formula I (wherein R<1> is a tetravalent organic group, R<2> is a divalent organic group, R<3> is H or a monovalent organic group, and R<6> is a monovalent organic group). A particularly preferred method for synthesizing the polymer comprises adding a dihydroquinoline derivative represented by formula II (wherein R4 and R5 each is a monovalent organic group) to a solution of a poly(amic acid) in an organic solvent and reacting the reactants to synthesize a polyisoimide. If necessary, an amine represented by the formula R<3>R<6>NH (wherein R<3> and R<6> each is a monovalent organic group) is added to the resulting solution and reacted.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a coating liquid for a liquid crystal alignment film and a method for producing the same.

[0002]

2. Description of the Related Art A polyimide film has been conventionally used as an alignment film for a liquid crystal display device. As a method for forming a polyimide film, a solution of polyamic acid or polyimide dissolved in an organic solvent is applied on a substrate by a printing method, and then baked to form a polyimide thin film having a thickness of several hundred to several thousand angstroms. It is a common method to blame. However, polyimide has poor solubility in organic solvents, and only polyimide having a special structure is soluble. Therefore, in many cases, a coating solution is formed by converting a polyamic acid into a polyimide by applying a solution obtained by dissolving a polyamic acid in an organic solvent and baking the solution. On the other hand, polyamic acid has a drawback that it is easily hydrolyzed by a trace amount of water present in the solvent, the viscosity of the solution changes with time, and therefore the film thickness changes. Particularly when applied by the printing method, since the polyamic acid solution is exposed to the air for a long time, the solution absorbs moisture in the air and the viscosity change becomes more severe.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal alignment film having excellent storage stability, and to provide a method for producing the same.

[0004]

[Means for Solving the Problems] The present inventors have conducted various studies in order to solve the above-mentioned problems associated with known techniques.
As a result, it was found that, as a polyimide precursor, polyamic acid amide was adopted, and by using a solution dissolved in an organic solvent thereof, a liquid crystal alignment film coating liquid in which the above problems were solved was obtained, The present invention has been completed based on the findings. The present invention has the following configurations (1) and (2). (1) A coating liquid for a liquid crystal alignment film containing a polyamic acid amide having a repeating unit represented by the following general formula (I) and an organic solvent as main components.

[Chemical 3] (However, R ¹ is tetravalent, R ² is divalent, R ³ is a hydrogen atom or a monovalent organic group, and R ⁶ is a monovalent organic group).

(2) The following general formula (II) is added to a solution containing polyamic acid and an organic solvent.

[Chemical 4] (However, R ⁴ and R ⁵ are independently a monovalent organic group.) A polyisoimide is synthesized by adding a dihydroquinoline derivative represented by the following general formula (III) R ³ R ⁶ NH (III) (provided that R ³ and R ⁶ are as described above)
A method for producing a coating liquid for a liquid crystal alignment film, characterized in that a polyamic acid amide solution is prepared by adding an amine represented by the above and carrying out a reaction.

The structure and effect of the present invention will be described in detail below. There are various possible methods for synthesizing the polyamic acid amide used in the liquid crystal alignment film coating liquid and the method for producing the liquid crystal alignment film of the present invention. A method of synthesizing and further reacting with an amine represented by the general formula (III) is particularly preferable.

The polyamic acid used in the method for producing the coating liquid for a liquid crystal alignment film of the present invention can be synthesized by reacting a tetracarboxylic dianhydride and a diamine in an organic solvent according to a conventional method.

Specific examples of the tetracarboxylic dianhydride used in the method for producing a coating liquid for a liquid crystal alignment film of the present invention include, as the aromatic tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4'-biphenyltetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetracarboxylic dianhydride, 3 , 3 ', 4,4'-Benzophenonetetracarboxylic dianhydride, 2,2', 3,3 '
-Benzophenone tetracarboxylic dianhydride, 2,3
3 ', 4'-benzophenone tetracarboxylic dianhydride, bis- (3,4-dicarboxyphenyl) ether dianhydride, bis- (3,4-dicarboxyphenyl) sulfone dianhydride, 1, 2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 2,2-bis- (3,4-dicarboxyphenyl) hexafluoropropane dianhydride Things,
Examples of the alicyclic tetracarboxylic acid dianhydride include cyclobutane tetracarboxylic acid dianhydride and methylcyclobutane tetracarboxylic acid dianhydride, and aliphatic tetracarboxylic acid dianhydrides include 1,2,3,4-tetraanhydride. Known compounds such as carboxybutane dianhydride can be mentioned. However, it is not necessarily limited to these.

Specific examples of the diamine include 4,4'-diaminodiphenyl ether and 3,4 as the aromatic diamine.
4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, 4,
4'-diaminodiphenyl sulfide, 4,4'-di (metaaminophenoxy) diphenyl sulfone, 4,
4'-di (paraaminophenoxy) diphenyl sulfone, orthophenylenediamine, metaphenylenediamine, paraphenylenediamine, benzidine, 3,3'-
Diaminobenzophenone, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl-2,2-propane, 1,5-diaminonaphthalene, 1,8-diaminonaphthalene, 4,4'-bis (4-aminophenoxy) )
Biphenyl, 2,2-bis {4- (4-aminophenoxy) phenyl} hexafluoropropane, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4
-Aminophenoxy) benzene, 4,4'-diamino-
3,3'-diethyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3 ', 5,5'-tetramethyldiphenylmethane, 1,4-diaminotoluene, metaxylylenediamine, 2, 2'-dimethylbenzidine, 2,2-bis {4- (4-aminophenoxy)
Phenyl} octane, 1,1-bis {4- (4-aminophenoxy) phenyl} cyclohexane, 1,1-bis {4- (4-aminophenoxy) phenyl} -4-methylcyclohexane, 1,1-bis { 4- (4-aminophenoxy) phenyl} -4-ethylcyclohexane,
1,1-bis {4- (4-aminophenoxy) phenyl} -4- (n-propyl) cyclohexane and the like, as the aliphatic diamine, trimethylenediamine, tetramethylenediamine, hexamethylenediamine, 2,11-dodecanediamine. As the silicon-based diamine, bis (paraaminophenoxy) dimethylsilane, 1,4-bis (3-aminopropyldimethylsilyl) benzene, etc., and as the alicyclic diamine, 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) ) Methane, isophoronediamine and the like, and guanamines include acetoguanamine and benzoguanamine. However, it is not necessarily limited to these.

The following compounds may be mentioned as specific examples of the coating liquid for a liquid crystal alignment film of the present invention and the solvent used in the method for producing the same. N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide,
Dimethyl sulfoxide, tetramethylurea, pyridine,
Hexamethylphosphoramide, methylformamide, N
-Acetyl-2-pyrrolidone, 2-methoxyethano-
2-ethoxyethanol, 2-butoxyethanol
, Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, cyclopentanone, methylcyclopentanone, cyclohexanone, cresol, γ-
Butyrolactone, isophorone, N, N-diethylacetamide, N, N-diethylformamide, N, N-dimethylmethoxyacetamide, tetrahydrofuran, N
-Methyl- [epsilon] -caprolactam, tetrahydrathiophene dioxide {sulpholan
e)}.

Further, the above-mentioned organic solvent is replaced with another aprotic (neutral) organic solvent such as aromatic, alicyclic or aliphatic hydrocarbon, or a chlorinated derivative thereof (for example,
(Benzene, toluene, xylenes, cyclohexane, pentane, hexane, petroleum ether, methylene chloride, etc.)
Alternatively, it may be diluted with dioxane or the like. Further, by-products such as alcohol and quinoline represented by the reaction formula (Formula 5) and amines represented by the general formula (III), which will be described later, can also be referred to as the organic solvent of the coating liquid and the production method of the present invention.

In the reaction of the tetracarboxylic dianhydride and the diamine in the synthesis of the polyamic acid, it is possible to improve the adhesion to the substrate by introducing aminosilane at the polymer terminal. Specific examples of the aminosilane include aminomethyl-di-n-propoxy-methylsilane, (β-aminoethyl) -n-propoxy-methylsilane, (β-aminoethyl) -diethoxy-phenylsilane, (β-aminoethyl). -Tri-n-propoxysilane, (β-aminoethyl) -dimethoxy-methylsilane, (γ-aminopropyl) -di-n-propoxy-methylsilane, (γ-aminopropyl) -di-n-
Butoxy-methylsilane, (γ-aminopropyl) -triethoxysilane, (γ-aminopropyl) -di-n-
Pentoxy-phenylsilane, (γ-aminopropyl)
-Methoxy-n-propoxy-methylsilane, (δ-aminobutyl) -dimethoxy-methylsilane, (3-aminophenyl) -di-n-propoxysilane, (4-aminophenyl) -tri-n-propoxysilane, {β −
(4-Aminophenyl) ethyl} -diethoxy-methylsilane, {β- (3-aminophenyl) ethyl} -di-
n-propoxy-phenylsilane, {γ- (4-aminophenyl) propyl} -di-n-propoxy-methylsilane, {γ- (4-aminophenoxy) propyl} -di-n-propoxy-methylsilane, {γ- (3-Aminophenoxy) propyl} -di-n-butoxy-methylsilane, {γ- (3-aminophenoxy) propyl} -dimethyl-methoxysilane, (γ-aminopropyl) -methyl-diethoxysilane, (γ- Aminopropyl) ethyl-di-n-propoxysilane, (4-aminophenyl) -trimethoxysilane, (3-aminophenyl)-
Trimethoxysilane, (4-aminophenyl) -methyl-dimethoxy-silane, (3-aminophenyl) -dimethyl-methoxysilane, (4-aminophenyl) -triethoxysilane, {3- (triethoxysilyl) propyl} Known compounds such as urea can be mentioned. However, it is not limited to these.

In addition to these compounds, one acid anhydride or a compound having an amino group, such as phthalic anhydride, maleic anhydride, aniline or monoallylamine, is used for the purpose of controlling the molecular weight of polyamic acid. It is also possible to carry out the reaction by adding.

The liquid crystal alignment film coating liquid of the present invention and the polyamic acid amide used in the method for producing the same are usually synthesized by two methods.
There is One of them is to synthesize polyamic acid with acid chloride such as thionyl chloride.
I) is a method of reacting an alcohol, and the other is to synthesize a polyisoimide by adding a dehydrating agent such as dicyclohexylcarbodiimide or a dihydroquinoline derivative represented by the general formula (II) to polyamic acid. Is a method of reacting this with an amine represented by the general formula (III). In this case, the dehydrating agent is preferably a dihydroquinoline derivative from the viewpoint of workability.

Specific examples of the dihydroquinoline derivative represented by the general formula (II) used in the method for producing the coating liquid of the present invention include N-methoxycarbonyl-2-methoxy-1,
2-dihydroquinoline, N-methoxycarbonyl-2-
Ethoxy-1,2-dihydroquinoline, N-ethoxycarbonyl-2-methoxy-1,2-dihydroquinoline,
N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline, N-propoxycarbonyl-2-propoxy-1,2-dihydroquinoline, N-propoxycarbonyl-2-propoxy-1,2-dihydroquinoline,
N-isobutoxycarbonyl-2-methoxy-1,2-
Dihydroquinoline, N-isobutoxycarbonyl-2-
Ethoxy-1,2-dihydroquinoline, N-isobutoxycarbonyl-2-isobutoxy-1,2-dihydroquinoline, N-pentoxycarbonyl-2-pentoxy-
1,2-dihydroquinoline and the like can be mentioned.
However, it is not limited to these.

In a solution of polyamic acid in an organic solvent, the above formula (I
By adding the dihydroquinoline derivative represented by I), a polyisoimide is produced. The reaction formula is shown below.

[Chemical 5] (However, R ¹ , R ² , R ⁴ , and R ⁵ are n as described above.
Is a positive integer. ) That is, a solution of the polyamic acid (a) in an organic solvent is added with the formula (I
The polyisoimide (b) is produced by adding the dihydroquinoline derivative represented by I).

Here, the carbon dioxide produced as a by-product is removed as a gas from the outside of the system, and since the alcohol and quinoline are dissolved in the solvent, it is not necessary to remove them again. The reaction temperature is 0 to 100 ° C, preferably 20 to 60 ° C. The reaction time is 0.5 to 50 hours, preferably 1 to 20 hours. Regarding the amount of the dihydroquinoline derivative added to the polyamic acid, theoretically all polyamic acid can be converted to polyisoimide by adding 2 molecules of the dihydroquinoline derivative to one amic acid repeating unit. However, there is no particular problem even if the hydroquinoline derivative is added in excess, and the amount may be small. When the amount is small, a polymer in which isoimide repeating units and amic acid repeating units are mixed is obtained. In addition, depending on the reaction conditions, the produced isoimide may be partially converted to an imide, and a polymer containing imide, isoimide and amic acid repeating units may be produced.

The reaction can be carried out by adding the amine represented by the general formula (III) to the solution of the polyisoimide thus obtained in the organic solvent.

Specific examples of the amine represented by the general formula (III) used in the method for producing the coating liquid for a liquid crystal alignment film of the present invention include methylamine, ethylamine, n-propylamine, i-propylamine and t-butylamine. , Primary amines such as 2-ethylhexylamine, allylamine, ventilamine, aniline, and ethanolamine, dimethylamine, diethylamine, methyl-n-propylamine, methyl-t-butylamine, diallylamine, methylventilamine, diethylanol, etc. Secondary amines and the like. However, it is not limited to these.

The reaction of polyisoimide and amine in the method for producing a coating liquid for liquid crystal alignment film of the present invention is 0 to 100 ° C.
It is preferably at 20 to 60 ° C. for 0.5 hours to 50 hours, preferably about 1 to 20 hours.

The solution of the polyamic acid amide in the organic solvent obtained by the method for producing a coating liquid for a liquid crystal alignment film of the present invention can be used as it is as a coating liquid for a liquid crystal alignment film of the present invention. In addition, one or more solvents used in the coating solution and the production method of the present invention may be added to dilute and be used, or may be concentrated and used. Alternatively, the reaction solution may be transferred to a large amount of a non-solvent to precipitate a polyamic acid amide, which is fractionated and dried, and then dissolved in one or more of the above organic solvents for use.

The method for forming a polyimide cured film from the liquid crystal alignment film coating liquid of the present invention may be any known method. The printing method is usually used as the coating method,
A known method such as a spin coat method is used. The coating film is heated to 100 to 400 ° C., preferably 180 to 28 by a heating means such as hot plate, far infrared ray or oven.
A polyimide cured film can be obtained by heating at 0 ° C. for 0.2 to 5 hours, preferably 0.5 to 2 hours. The alignment film for liquid crystal is obtained by rubbing the cured film in one direction with a cloth or the like.

[0023]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Rotational viscosity in Examples and Comparative Examples is an E-type viscometer (manufactured by Tokyo Keiki Co., Ltd.
Viscosity measured at a temperature of 25 ± 0.1 ° C. using EMD). Further, the change with time of the viscosity was determined by keeping the polyamic acid amide solutions obtained in Examples and the polyamic acid solutions obtained in Comparative Examples 1 to 6 at a temperature of 20 to 25 ° C. for 30 days, and then measuring the rotational viscosities of the respective solutions. It was measured.

(Example 1) A 1-liter flask equipped with a stirrer, a thermometer, a condenser and a nitrogen purging device was fixed in a constant temperature bath. After replacing the inside of the system with nitrogen gas, 500 g of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP), pyromellitic dianhydride (hereinafter PMD)
6.20 g (0.0284 mol) and 1,1-bis {4- (4-aminophenyloxy) phenyl} -4-ethylcyclohexane 11.93 g (0.0).
249 mol) was added and the reaction was carried out at 20 to 30 ° C. for 20 hours to obtain a polyamic acid solution having a rotational viscosity of 19 centipoise. N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (hereinafter referred to as EE) was added to half of this solution.
7.16 g (0.0290 mol) of DQ) was added and reacted at 30 to 40 ° C. for 30 hours to obtain a polyisoimide solution. The infrared absorption spectrum of the film obtained by drying this solution at room temperature is shown in FIG. To this solution was added 1.65 g (0.0290 mol) of allylamine, and 30
The reaction was carried out at -40 ° C for 20 hours to obtain a polyamic acid amide solution having a rotational viscosity of 19 centipoise, that is, a coating liquid for a liquid crystal alignment film of the present invention. The infrared absorption spectrum of the film obtained by drying this solution at room temperature is shown in FIG. (Comparative Example 1) Table 2 shows changes in viscosity of the polyamic acid solution obtained in Example 1 with time.

Example 2 By the same apparatus and method as in Example 1, N, N-dimethylacetamide (hereinafter DMA)
500 g, PMDA 5.05 g (0.0)
232 mol), 2,2-bis {4- (4-aminophenoxy) phenyl} octane 13.09 g (0.0232)
Mol) and carry out a reaction at 20 to 30 ° C. for 20 hours,
A polyamic acid solution having a rotational viscosity of 32 centipoise was obtained. 5.73 g of EEDQ (0.03%) was added to half of this solution.
232 mol) was added and reacted at 20 to 30 ° C. for 30 hours to obtain a polyisoimide solution. 2.25 g (0.0232 mol) of diallylamine was added to this solution,
The reaction was carried out at 30 ° C. for 15 hours to obtain a polyamic acid amide solution having a rotational viscosity of 30 centipoise, that is, a coating liquid for a liquid crystal alignment film of the present invention. (Comparative Example 2) Table 2 shows the change with time of the viscosity of the polyamic acid solution obtained in Example 2.

(Example 3) Using the same apparatus and method as in Example 1, 500 g of NMP and 7.19 g (0.02 g) of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride.
45 mol), 1,1-bis {4- (4-aminophenoxy) phenyl} cyclohexane 10.48 g (0.02
32 mol) and 4-aminophenyltrimethoxysilane (0.469 g, 0.00220 mol) were added, and 20 to
The reaction was carried out at 30 ° C. for 20 hours to obtain a polyamic acid solution having a rotational viscosity of 31 centipoise. 6.18 g (0.0250 mol) of EEDQ was added to half of this solution, and 2
Reaction was carried out at 0 to 30 ° C. for 30 hours to obtain a polyisoimide solution. 2.68 g of benzylamine (0.
0250 mol) and reacted at 20 to 30 ° C. for 15 hours to obtain a polyamic acid amide solution of the present invention having a rotational viscosity of 33 centipoise, that is, a liquid crystal alignment film coating solution of the present invention. (Comparative Example 3) Table 2 shows the change with time of the viscosity of the polyamic acid solution obtained in Example 3.

(Embodiment 4) Using the same apparatus and method as in Embodiment 1, NMP300g, DMAC200g, PMD
A 9.46 g (0.0434 mol) and 4,4'-diaminodiphenyl ether 8.65 g (0.0433 mol) were added, the reaction was carried out at 20 to 30 ° C for 20 hours, and the rotational viscosity was 33 centipoise. A polyamic acid solution was obtained. 11.1 g (0.04%) of EEDQ was added to half of this solution.
50 mol) was added and reacted at 20 to 30 ° C. for 30 hours to obtain a polyisoimide solution. To this solution, 5.81 g (0.0450 mol) of 2-ethylhexylamine was added, and the mixture was reacted at 30 to 40 ° C for 24 hours, and the rotational viscosity was 3
A 1 centipoise polyamic acid amide solution, that is, a coating liquid for a liquid crystal alignment film of the present invention was obtained. (Comparative Example 4) Table 2 shows changes with time in viscosity of the polyamic acid solution obtained in Example 4.

(Example 5) By the same apparatus and method as in Example 1, NMP 500 g, 3,3 ', 4,4'-benzophenone tetracarboxylic acid dianhydride 7.74 g (0.
Polyamic acid having a rotational viscosity of 38 centipoise and 20.30 ° C. for 20 hours, charged with bis {4- (4-aminophenoxy) phenyl} sulfone 10.39 g (0.0240 mol). A solution was obtained. 5.93 g (0.02 g) of EEDQ was added to half of this solution.
(40 mol) and reacted at 20 to 30 ° C. for 30 hours to obtain a polyisoimide solution. To this solution was added 1.47 g (0.0240 mol) of ethanolamine, and 30
The reaction was carried out at -40 ° C for 10 hours to obtain a polyamic acid amide solution of the present invention having a rotational viscosity of 34 centipoise, that is, a liquid crystal alignment film coating liquid of the present invention. (Comparative Example 5) Table 2 shows the change with time of the viscosity of the polyamic acid solution obtained in Example 5.

Example 6 Using the same apparatus and method as in Example 1, NMP 400 g, γ-butyrolactone 100
g, 4,4'-oxydiphthalic anhydride 11.06 g
(0.0357 mol) and 4,4'-diaminodiphenylmethane (7.06 g, 0.0357 mol) were added and 2
The reaction was carried out at 0 to 30 ° C. for 20 hours to obtain a polyamic acid solution having a rotational viscosity of 29 centipoise. To the half amount of this solution, 9.02 g (0.0365 mol) of EEDQ was added and reacted at 20 to 30 ° C. for 30 hours to obtain a polyisoimide solution. 3. Add cyclohexylamine to this solution.
Add 62 g (0.0365 mol), and add 3 at 10-20 ° C.
The reaction was carried out for 0 hours to obtain a polyamic acid amide solution having a rotational viscosity of 27 centipoise, that is, a coating liquid for liquid crystal alignment film of the present invention. (Comparative Example 6) Table 2 shows the change with time of the viscosity of the polyamic acid solution obtained in Example 6.

[Example 7 (application example)] An indium oxide-based transparent conductive film (ITO film) was provided as an electrode on one surface, and a silane coupling agent APS-E {Chisso Corporation) was prepared in advance.
Example 1 on a transparent glass substrate surface-treated with
Each of the coating liquids for a liquid crystal alignment film of the present invention obtained in Examples 1 to 6 was spin-coated. After coating, heating was performed at 250 ° C. for 1 hour to obtain a polyimide thin film having a film thickness of 1000 ± 200 angstrom. The infrared absorption spectrum of the polyimide thin film obtained from Example 1 is shown in FIG. Next, the coated surfaces of the two substrates were rubbed with a rubbing device to obtain a liquid crystal alignment film.
Using a substrate having this alignment film, a liquid crystal cell having a cell thickness of 10 μm was assembled so that the rubbing directions were parallel and opposed to each other, and a liquid crystal composition YY-400 manufactured by Chisso Corporation was assembled.
6 was enclosed. After the encapsulation, the liquid crystal element was obtained by heating to an isotropic liquid temperature and gradually cooling. The orientation of these liquid crystal elements was all good.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

According to the production method of the present invention, a coating liquid (polyamic acid amide solution) for a liquid crystal alignment film can be easily obtained, and the viscosity of the coating liquid does not change with time and has excellent storage stability. The practicality as a coating liquid is excellent.

[Brief description of drawings]

FIG. 1 is an infrared absorption spectrum of polyisoimide.

FIG. 2 is an infrared absorption spectrum of polyamic acid amide.

FIG. 3 is an infrared absorption spectrum of polyimide.

Claims (2)

[Claims] 1. A coating liquid for a liquid crystal alignment film, which comprises a polyamic acid amide having a repeating unit represented by the following general formula (I) and an organic solvent as main components. [Chemical 1] (However, R ¹ is tetravalent, R ² is divalent, R ³ is a hydrogen atom or a monovalent organic group, and R ⁶ is a monovalent organic group). 2. A solution containing polyamic acid and an organic solvent is represented by the following general formula (II): (However, R ⁴ and R ⁵ are independently a monovalent organic group.) A polyisoimide is synthesized by adding a dihydroquinoline derivative represented by the following general formula (III) R ³ R ⁶ NH (III) (wherein R ³ and R ⁶ are monovalent organic groups) are added to carry out a reaction to prepare a polyamic acid amide solution. A characteristic method for producing a coating liquid for a liquid crystal alignment film.