JP3201273B2 - Method for forming liquid crystal alignment film and liquid crystal display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a liquid crystal alignment film of a liquid crystal display device , and more particularly, to a method using a liquid crystal alignment agent.
Crystal orientation have a thickness uniformity high liquid crystal alignment film by a printing method can be formed by, good liquid crystal alignment property, the reliability in high pretilt angle and long-term use can be expressed on a liquid crystal display device Film formation method, arrangement
And a liquid crystal display device .

[0002]

2. Description of the Related Art At present, as a liquid crystal display device, a liquid crystal alignment film is formed on a surface of a substrate on which a transparent conductive film is provided to form a substrate for a liquid crystal display device. A nematic liquid crystal layer having a positive dielectric anisotropy is formed therein to form a sandwich cell, and the major axis of the liquid crystal molecules is continuously twisted by 90 degrees from one substrate to the other substrate. The so-called TN (Twi
2. Description of the Related Art A TN-type liquid crystal display device having a stable nematic (liquid crystal) type liquid crystal cell is known. Orientation of liquid crystal molecules in a liquid crystal display device such as a TN type liquid crystal display device is usually
This is realized by a liquid crystal alignment film provided with an alignment ability for liquid crystal molecules by rubbing treatment. Here, as a material of the liquid crystal alignment film constituting the liquid crystal display element, polyamic acid and an imidized polymer obtained by dehydrating and cyclizing polyamic acid are conventionally known. These materials have heat resistance and affinity for liquid crystal. It is used in many liquid crystal display devices because of its excellent properties and mechanical strength.

[0003]

However, a conventionally known liquid crystal aligning agent containing a polyamic acid and / or an imidized polymer is applied to a substrate for a liquid crystal display element by, for example, a printing method. In such a case, it is difficult to form a thin film having a high uniformity of the film thickness. For example, the thin film is formed in a state having a considerably large thickness unevenness exceeding 50 °. There is a problem that it is not possible to form a liquid crystal alignment film that can obtain characteristics. Further, it is difficult to develop a high pretilt angle (for example, 3 ° or more) in a liquid crystal alignment film formed by a conventionally known liquid crystal alignment agent containing a polyamic acid and / or an imidized polymer, The recent demand for higher brightness and higher definition of liquid crystal display devices cannot be sufficiently satisfied. Furthermore, in a liquid crystal display device having a liquid crystal alignment film formed by a conventionally known liquid crystal alignment agent containing a polyamic acid and / or an imidized polymer, when the liquid crystal display device is used for a long time, white A spot-like display defect may occur, which has impaired the reliability of the liquid crystal display element.

The present invention has been made in view of the above circumstances, and an object of the present invention is to use a small amount of a liquid crystal aligning agent.
As a result, a thin film with high film thickness uniformity is formed, and the liquid crystal alignment is excellent.
To achieve a high pretilt angle in the liquid crystal display device
It is an object of the present invention to provide a method for forming a liquid crystal alignment film that can be used.
Another object of the present invention is to provide a liquid crystal display even after prolonged use.
Highly reliable liquid crystal that does not cause display defects in the device
It is to provide a display element.

[0005]

Means for Solving the Problems To achieve the above object, the inventors of the present invention have conducted intensive studies, and as a result, the uniformity of the thickness of a thin film formed by a liquid crystal aligning agent has been found to be small. ), It depends not only on the surface free energy of the liquid crystal alignment agent (polymer solution) for obtaining the thin film, but also by setting these two surface free energies to specific ranges. Among them, they found that outstandingly excellent film thickness uniformity was exhibited irrespective of the type of the solvent, and based on this finding, completed the present invention.

[0006] The method for forming a liquid crystal alignment film of the present invention comprises at least one kind selected from polyamic acid (hereinafter also referred to as "polymer A") and its imidized polymer (hereinafter also referred to as "polymer B"). Contains polymer , surface free energy
Exceeds 30 dyn / cm, but not more than 38 dyn / cm
By applying and drying a liquid crystal alignment agent consisting of a liquid,
The surface free energy exceeds 38 dyn / cm and 50 dy
n / cm or less, with a maximum thickness difference of 25 ° or less
The method is characterized in that a film is formed. Liquid crystal display element of the present invention
Gives orientation ability to the thin film formed by the above method
It is characterized by comprising a liquid crystal alignment film formed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The liquid crystal aligning agent used in the method of the present invention (hereinafter, referred to as
Polymer A Constituting "Liquid Crystal Alignment Agent of the Present Invention")
Is a polyamic acid obtained by reacting a tetracarboxylic dianhydride with a diamine compound. The polymer B constituting the liquid crystal aligning agent of the present invention is an imide having a structure obtained by dehydrating and ring-closing this polymer A. Polymer.

<Tetracarboxylic dianhydride> The tetracarboxylic dianhydride used in the synthesis of the polymer A is not particularly limited. For example, butanetetracarboxylic dianhydride, 1,2,3 , 4-cyclobutanetetracarboxylic dianhydride, 1,2-dimethyl-1,2,3,4
-Cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dichloro-1,2,3,4-cyclobutanetetracarboxylic dianhydride Anhydride, 1,2,3,4-
Tetramethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride Thing, 3,3 ', 4,4'-
Dicyclohexyltetracarboxylic dianhydride, 2,3
5-tricarboxycyclopentylacetic acid dianhydride, 3,
5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5 (tetrahydro-2 , 5-Dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5-
Methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5
-Ethyl-5 (tetrahydro-2,5-dioxo-3-
Furanyl) -naphtho [1,2-c] -furan-1,3-
Dione, 1,3,3a, 4,5,9b-hexahydro-
7-methyl-5 (tetrahydro-2,5-dioxo-3
-Furanyl) -naphtho [1,2-c] -furan-1,3
-Dione, 1,3,3a, 4,5,9b-hexahydro-7-ethyl-5 (tetrahydro-2,5-dioxo-
3-furanyl) -naphtho [1,2-c] -furan-1,
3-dione, 1,3,3a, 4,5,9b-hexahydro-8-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-
1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-ethyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan- 1,3-dione, 1,3,3a, 4,5,9b-hexahydro-5,8-dimethyl-5 (tetrahydro-2,
5-dioxo-3-furanyl) -naphtho [1,2-c]
-Furan-1,3-dione, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, bicyclo [2,2,
2] -oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, aliphatic tetracarboxylic dianhydrides such as compounds represented by the following general formulas [I] to [II], and Alicyclic tetracarboxylic dianhydride;

Pyromellitic dianhydride, 3,3 ', 4
4'-benzophenonetetracarboxylic dianhydride, 3,
3 ', 4,4'-biphenylsulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3 , 3 ′, 4,4′-biphenylethertetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride,
3,3 ', 4,4'-tetraphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic dianhydride, 4,4'-bis (3,4-dicarboxyphenoxy) ) Diphenyl sulfide dianhydride, 4,4 '
-Bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 3,
3 ', 4,4'-perfluoroisopropylidene diphthalic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p -Phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4'-diphenyl ether dianhydride, bis (tri Phenylphthalic acid) -4,4′-diphenylmethane dianhydride, ethylene glycol-bis (anhydrotrimellitate), propylene glycol-bis (anhydrotrimellitate), 1,4-butanediol-bis (anhydrotrimeritate) Trimellitate), 1,6-hexanediol-bis (anhydrotrimellitate),
1,8-octanediol-bis (anhydrotrimellitate), 2,2-bis (4-hydroxyphenyl) propane-bis (anhydrotrimellitate), represented by the following formulas (1) to (4) And aromatic tetracarboxylic dianhydrides such as These are used alone or in combination of two or more.

[0010]

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(Where R¹And R^ThreeHas an aromatic ring
A divalent organic group represented by^TwoAnd R ^FourIs a hydrogen atom
Or an alkyl group. Multiple R^TwoAnd R
^FourMay be the same or different. )

[0012]

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Of these, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride Anhydride, 1,2,3,4-
Cyclopentanetetracarboxylic dianhydride, 2,3,5
-Tricarboxycyclopentylacetic dianhydride, 5-
(2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5-
(Tetrahydro-2,5-dioxo-3-furanyl)-
Naphtho [1,2-c] furan-1,3-dione, 1,
3,3a, 4,5,9b-hexahydro-8-methyl-
5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione;
1,3,3a, 4,5,9b-hexahydro-5,8-
Dimethyl-5- (tetrahydro-2,5-dioxo-3
-Furanyl) -naphtho [1,2-c] furan-1,3-
Dione, bicyclo [2,2,2] -oct-7-ene-
2,3,5,6-tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′- Biphenylsulfonetetracarboxylic dianhydride, 1,4
5,8-Naphthalenetetracarboxylic dianhydride, among the compounds represented by the above general formula [I], the following formulas (5) to
Of the compounds represented by the formula (7) and the compounds represented by the above general formula [II], the compounds represented by the following formula (8) are preferable from the viewpoint that good liquid crystal alignment can be exhibited. Preferred are 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride and 2,3,5-tricarboxy. Cyclopentylacetic acid dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3- Zeon,
1,3,3a, 4,5,9b-hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione; Examples thereof include pyromellitic dianhydride and a compound represented by the following formula (5).

[0014]

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<Diamine Compound> The diamine compound used for the synthesis of the polymer A is not particularly limited, and for example, p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane,
4'-diaminodiphenylethane, 4,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminobenzanilide, 4 ,
4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4'-diaminobiphenyl, 5-amino-1- (4'-aminophenyl)
-1,3,3-trimethylindane, 6-amino-1-
(4′-aminophenyl) -1,3,3-trimethylindane, 3,4′-diaminodiphenyl ether, 3,
3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone,
2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexa Fluoropropane,
2,2-bis [4- (4-aminophenoxy) phenyl] sulfone, 1,4-bis (4-aminophenoxy)
Benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) -10-hydroanthracene, 2,7-diamino Fluorene, 9,9
-Bis (4-aminophenyl) fluorene, 4,4'-
Methylene-bis (2-chloroaniline), 2,2 ′,
5,5′-tetrachloro-4,4′-diaminobiphenyl, 2,2′-dichloro-4,4′-diamino-5
5'-dimethoxybiphenyl, 3,3'-dimethoxy-
4,4'-diaminobiphenyl, 1,4.4 '-(p-
Phenyleneisopropylidene) bisaniline, 4,4 '
-(M-phenyleneisopropylidene) bisaniline,
2,2′-bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane, 4,4′-diamino-2,2′-bis (trifluoromethyl) biphenyl, 4,4 Aromatic diamines such as' -bis [(4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl;

1,1-meta-xylylenediamine, 1,3
-Propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclo Pentadienylenediamine, hexahydro-4,7-methanoindanylene dimethylenediamine, tricyclo [6,2,1,02.7]-
Aliphatic and alicyclic diamines such as undecylenedimethyldiamine and 4,4'-methylenebis (cyclohexylamine); monosubstituted phenylenediamines represented by the following general formula [III]; represented by the following general formula [IV] Diaminoorganosiloxane; and compounds represented by the following formulas (9) to (13). These diamine compounds can be used alone or in combination of two or more.

[0017]

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(Wherein R ⁵ represents —O—, —COO—,
OCO-, -NHCO-, -CONH- and -CO-
And R ⁶ represents a monovalent organic group having a steroid skeleton or a trifluoromethyl group. )

[0019]

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(Wherein, R ⁷ represents a hydrocarbon group having 1 to 12 carbon atoms, and a plurality of R ^{7 s} may be the same or different. P is an integer of 1 to 3) , Q is an integer of 1 to 20.)

[0021]

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(In the formula, y is an integer of 2 to 12, and z is an integer of 1 to 5.)

Of these, p-phenylenediamine,
4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 1,5-diaminonaphthalene, 2,7-diaminofluorene, 4,4'-diaminodiphenylether, 2,2-bis [4- (4- Aminophenoxy) phenyl] propane, 9,9-bis (4-
Aminophenyl) fluorene, 2,2-bis [4- (4
-Aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4 ′-(p-phenylenediisopropylidene) bisaniline, 4,4 ′-(m-phenylene Isopropylidene) bisaniline, 1,4-cyclohexanediamine, 4,4′-methylenebis (cyclohexylamine), 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl, Among the compounds represented by the above formulas (9) to (13) and the compound represented by the above general formula [III], the following formula (1)
Compounds represented by 4) to (18) are preferred.

[0024]

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<Polymer A> The ratio of the tetracarboxylic dianhydride and the diamine compound used in the synthesis reaction of the polymer A is such that the tetracarboxylic dianhydride is equivalent to 1 equivalent of the amino group contained in the diamine compound. Acid anhydride groups of 0.2 to
The ratio is preferably 2 equivalents, more preferably 0.3 to 1.2 equivalents.

The synthesis reaction of the polymer A is carried out in an organic solvent at a reaction temperature of usually 0 to 150 ° C., preferably 0 to 100 ° C. for 1 to 48 hours. The organic solvent is not particularly limited as long as it can dissolve the polymer A produced by the reaction. Specifically, for example, N-methyl-2-
Pyrrolidone, N, N-dimethylacetamide, N, N-
Aprotic polar solvents such as dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, and hexamethylphosphortriamide; and phenolic solvents such as m-cresol, xylenol, phenol and halogenated phenol. Usually, the amount of the organic solvent used is preferably such that the total amount of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 30% by weight based on the total amount of the reaction solution.

The above-mentioned organic solvent precipitates polymer A, which produces alcohols, ketones, esters, ethers, halogenated hydrocarbons, hydrocarbons, etc., which are poor solvents for polymer A. It can be used together within the range not to do. Specific examples of such poor solvents include, for example, methyl alcohol, ethyl alcohol, isopropyl alcohol,
Cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, triethylene glycol, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, diethyl malonate, methyl lactate, ethyl lactate, lactic acid Purpyl, butyl lactate, pentyl lactate, diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, ethylene glycol hexyl ether,
Ethylene glycol monophenyl ether, ethylene glycol methyl phenyl ether, ethylene glycol ethyl phenyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether,
Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, ethylene glycol methyl ether acetate, ethylene glycol ethyl ether acetate, 4-hydroxy-4-methyl-2-
Pentanone, ethyl 2-hydroxypropionate, 2-
Ethyl hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2-hydroxy-3-
Methyl methylbutanoate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl 3-ethoxypropionate, methyl 3-ethoxypropionate,
3-methyl-3-methoxybutanol, 3-ethyl-3
-Methoxybutanol, 2-methyl-2-methoxybutanol, 2-ethyl-2-methoxybutanol, 3-methyl-3-ethoxybutanol, 3-ethyl-3-ethoxybutanol, 2-methyl-2-methoxybutanol, 2 -Ethyl-2-ethoxybutanol, tetrahydrofuran, dichloromethane, 1,2-dichloroethane,
1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane,
Octane, benzene, toluene, xylene and the like can be mentioned. These may be used alone or in combination of two or more.

By the above synthesis reaction, a reaction solution obtained by dissolving the polymer A is obtained. The reaction solution is poured into a large amount of a poor solvent to obtain a precipitate, and the precipitate is dried under reduced pressure to obtain a polymer A. Further, by performing the step of dissolving the polymer A again in the organic solvent and then precipitating with the poor solvent once or several times,
Purification of polymer A can be performed.

<Polymer B> The polymer B constituting the liquid crystal aligning agent of the present invention can be prepared by subjecting the polymer A to dehydration and ring closure. The dehydration ring closure of the polymer A is performed by (i)
By heating polymer A, or (ii) polymer A
Is dissolved in an organic solvent, a dehydrating agent and a dehydration ring-closing catalyst are added to the solution, and the solution is heated if necessary.

The reaction temperature in the method (i) for heating the polymer A is usually 50 to 200 ° C., preferably 60 to 170 ° C. When the reaction temperature is lower than 50 ° C., the dehydration ring-closing reaction does not sufficiently proceed, and when the reaction temperature exceeds 200 ° C., the molecular weight of the obtained polymer B may decrease.

On the other hand, in the method (ii) of adding a dehydrating agent and a dehydration ring-closing catalyst to the solution of the polymer A, the dehydrating agent may be, for example, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride. Things can be used. The amount of the dehydrating agent used is preferably 0.01 to 20 mol per 1 mol of the repeating unit of the polymer A. Examples of the dehydration ring-closing catalyst include, but are not limited to, tertiary amines such as pyridine, collidine, lutidine, and triethylamine. The amount of the dehydration ring-closing catalyst used is preferably 0.01 to 10 mol per 1 mol of the dehydrating agent used. In addition,
The organic solvent used in the dehydration ring closure reaction includes polymer A
The organic solvents exemplified as those used in the synthesis of can be mentioned. And the reaction temperature of the dehydration ring closure reaction is
Usually, it is 0 to 180 ° C, preferably 10 to 150 ° C. The polymer B can be purified by performing the same operation as the method for purifying the polymer A on the reaction solution thus obtained.

<Terminal-Modified Polymer> The polymer constituting the liquid crystal aligning agent of the present invention may be a terminal-modified polymer having a controlled molecular weight. By using this terminal-modified polymer, the coating characteristics of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. Such a terminal-modified type can be synthesized by adding an acid monoanhydride, a monoamine compound, a monoisocyanate compound, or the like to the reaction system when synthesizing the polymer A. Here, as the acid monoanhydride, for example, maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride,
Examples thereof include n-tetradecyl succinic anhydride and n-hexadecyl succinic anhydride.
Examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine, n-pentylamine, n-hexylamine, n-heptylamine, and n-butylamine.
-Octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-
Examples thereof include tridecylamine, n-tetradecylamine, n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine, and n-eicosylamine. In addition, examples of the monoisocyanate compound include phenyl isocyanate and naphthyl isocyanate.

<Logarithmic Viscosity of Polymer> The polymer constituting the liquid crystal aligning agent of the present invention has a logarithmic viscosity (ηln) of:
It is preferably 0.05 to 10 dl / g, more preferably 0.05 to 5 dl / g. Here, the value of the logarithmic viscosity (ηln) is obtained by measuring the viscosity at 30 ° C. of a solution having a polymer concentration of 0.5 g / 100 ml using N-methyl-2-pyrrolidone as a solvent. Is required by

[0034]

(Equation 1)

<Liquid Crystal Alignment Agent> The liquid crystal alignment agent of the present invention comprises a solution (polymer solution) containing the polymer A and / or the polymer B in an organic solvent. The liquid crystal alignment agent of the present invention is applied to the substrate surface by, for example, a printing method or a spin coating method, and the coating film is dried to remove the solvent, thereby forming a thin film as an alignment film material.

The content ratio of the polymer (Polymer A and / or Polymer B) in the liquid crystal aligning agent of the present invention is selected in consideration of viscosity, volatility, and the like. The content is in the range of 1 to 20% by weight, more preferably 1 to 10% by weight. 0.1% by weight of polymer
If it is less than 10%, the thickness of the formed thin film may be too small to obtain a good liquid crystal alignment film, and if it exceeds 20% by weight, the thickness of the thin film may become too large. In some cases, it is difficult to obtain a good liquid crystal alignment film, and the viscosity of the liquid crystal alignment agent is increased, resulting in poor coating characteristics.

As the organic solvent for dissolving the polymer, the polymer is dissolved and the surface free energy is 30 dyn / c.
m can be used alone or in combination of two or more from among those capable of obtaining a solution having a viscosity of more than m and not more than 38 dyn / cm. The surface free energy of the solution is 38
If it exceeds dyn / cm, the wettability of the solution to the substrate is not sufficient, and if it is 30 dyn / cm or less,
Since the compatibility of the polymer with the solvent is not sufficient, the resulting thin films are all poor in film thickness uniformity.

The liquid crystal aligning agent of the present invention has a surface free energy as a solution of more than 30 dyn / cm and 38 dyn / cm.
/ Cm or less, preferably 32 to 38 dyn / cm
It is said. The surface free energy refers to a value at 25 ° C. By setting the surface free energy of the solution within the above range, the uniformity of the thickness of the formed thin film becomes remarkably excellent. As a result, excellent display characteristics are exhibited in the finally obtained liquid crystal display element, and various characteristics (film thickness) excellent in the liquid crystal display element even when the amount of application to the substrate is small. Uniformity, liquid crystal alignment, and high pretilt angle). This surface free energy is 30d
In both cases where the surface free energy is not more than 38 dynes / cm and when the surface free energy exceeds 38 dynes / cm, the uniformity of the thickness of the formed thin film is sharply reduced and the obtained liquid crystal display device has excellent liquid crystal. It does not have orientation.

As a method of adjusting the surface free energy of the solution to the above range, for example, a method of obtaining a liquid crystal aligning agent by using an organic solvent capable of dissolving a polymer and a poor solvent for the polymer is used. . Examples of the organic solvent capable of dissolving the polymer include the solvents exemplified as those used in the synthesis reaction of polymer A and the dehydration ring closure reaction. Examples of the poor solvent include the poor solvents exemplified as those that can be used in combination during the synthesis reaction of the polymer A. By using these poor solvents together, the surface free energy of the solution is reduced. And can be adjusted to the above range.

The liquid crystal aligning agent of the present invention forms a thin film having a surface free energy of more than 38 dyn / cm and not more than 50 dyn / cm. When the liquid crystal aligning agent is 38
When a thin film having a surface free energy of dyn / cm or less is applied, the film tends to foam, the uniformity of the film thickness is impaired, and the obtained liquid crystal display element does not have good liquid crystal alignment. On the other hand, when the liquid crystal aligning agent gives a thin film having a surface free energy exceeding 50 dyn / cm, a high pretilt angle cannot be exhibited in the obtained liquid crystal display element, and the liquid crystal display element cannot be used for a long time. Display defects occur when the device is used.

As a method of adjusting the surface free energy of the formed thin film to the above range, for example, as a polymer constituting the liquid crystal aligning agent, a polymer giving a thin film having a high surface free energy and a polymer having a low surface free energy are used. A method in which a polymer for forming a thin film is mixed with an appropriate ratio and used. In particular, a polymer that gives a thin film with low surface free energy by introducing a compound containing a fluorine atom or a long-chain alkyl group into a tetracarboxylic dianhydride and / or a diamine compound used for the synthesis of the polymer Is obtained.

The liquid crystal aligning agent of the present invention may contain a functional silane-containing compound or an epoxy group-containing compound from the viewpoint of improving the adhesion of the thin film to the substrate surface. Examples of such functional silane-containing compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-amino Ethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3 -Aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N-triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 1
0-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-trimethoxysilyl-3,6-diazanonyl acetate, 9-triethoxysilyl-3 , 6-Diazanonyl acetate, N-benzyl-3-aminopropyltrimethoxysilane, N-benzyl-3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3- Examples thereof include aminopropyltriethoxysilane, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, and N-bis (oxyethylene) -3-aminopropyltriethoxysilane. Further, as the epoxy group-containing compound, for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether,
Polypropylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin diglycidyl ether, 2,2-dibromoneopentyl glycol diglycidyl ether, 1,3,5,6-tetraglycidyl −2,4-hexanediol, N, N,
N ', N',-tetraglycidyl-m-xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ', N',-tetraglycidyl-4,4 ' -Diaminodiphenylmethane and the like can be mentioned as preferred. The mixing ratio of these functional silane-containing compounds and epoxy group-containing compounds is usually 40 parts by weight or less, preferably 0.1 to 30 parts by weight, based on 100 parts by weight of the polymer.

<Liquid Crystal Display Device> A liquid crystal display device having a liquid crystal alignment film according to the present invention can be manufactured, for example, by the following method. (1) The liquid crystal aligning agent of the present invention is applied to the transparent conductive film side of the substrate on which the patterned transparent conductive film is provided, for example, by a method such as a roll coater method, a spinner method, or a printing method. A film is formed by heating. Here, as the substrate, for example, float glass,
A transparent substrate made of glass such as soda glass, a plastic film of polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, polycarbonate, or the like can be used. As the transparent conductive film provided on one surface of the substrate, NE made of SnO ₂ is used.
An SA film, an ITO film made of In ₂ O ₃ —SnO, or the like can be used. For the patterning of these transparent conductive films, a photo-etching method, a method using a mask in advance, or the like is used. In applying the liquid crystal aligning agent, a functional silane-containing compound, titanate, or the like may be applied on the substrate and the transparent conductive film in advance to further improve the adhesion between the substrate and the transparent conductive film and the thin film. . The heating temperature is set to 80 to 250 ° C., preferably 120 to 250 ° C.
~ 200 ° C. The thickness of the formed film is usually
0.001 to 1 μm, preferably 0.005 to 0.5 μm
m.

(2) The formed film is subjected to a rubbing treatment of rubbing in a certain direction with a roll around which a cloth made of a synthetic fiber such as nylon or rayon is wound, so that the film is provided with the ability to align liquid crystal molecules. It becomes an alignment film. Also,
In addition to the rubbing method, a liquid crystal alignment film may be formed by irradiating the surface of the film with polarized ultraviolet rays to impart alignment ability, or by a method of obtaining a film by a uniaxial stretching method, a Langmuir-Blodgett method, or the like. it can. Note that the formed liquid crystal alignment film is preferably washed with isopropyl alcohol or the like in order to remove fine powder (foreign matter) generated during the rubbing treatment and keep the surface clean. Further, by partially irradiating the liquid crystal alignment film formed by the liquid crystal alignment agent of the present invention with ultraviolet rays as shown in, for example, JP-A-6-222366 and JP-A-6-281937. A process in which a pretilt angle is changed or a resist film is partially formed on a rubbed liquid crystal alignment film as shown in JP-A-5-107544, which is different from the preceding rubbing process. After performing the rubbing process in the direction, by removing the resist film and performing a process for changing the alignment ability of the liquid crystal alignment film, the visibility characteristics of the liquid crystal display element can be improved.

(3) Two substrates on which the liquid crystal alignment films are formed as described above are prepared, and the two substrates are separated by a gap (so that the rubbing directions of the respective liquid crystal alignment films are orthogonal or antiparallel). (A cell gap), the peripheral portions of the two substrates are bonded together with a sealant, and liquid crystal is filled into the surface of the substrate and the cell gap defined by the sealant, and the filling hole is sealed. To form a liquid crystal cell.
Then, a polarizing plate is provided on the outer surface of the liquid crystal cell, that is, on the other surface side of each substrate constituting the liquid crystal cell, and the polarization direction thereof coincides with or is orthogonal to the rubbing direction of the liquid crystal alignment film formed on one surface of the substrate. Thus, a liquid crystal display element is obtained. As the sealant,
For example, an epoxy resin containing a hardening agent and aluminum oxide spheres as a spacer can be used. Examples of the liquid crystal include a nematic liquid crystal and a smectic liquid crystal, and among them, a nematic liquid crystal is preferable, for example, a Schiff base liquid crystal, an azoxy liquid crystal, a biphenyl liquid crystal, a phenylcyclohexane liquid crystal, an ester liquid crystal, and a terphenyl liquid crystal. Liquid crystal, biphenylcyclohexane liquid crystal, pyrimidine liquid crystal, dioxane liquid crystal, bicyclooctane liquid crystal, cubane liquid crystal and the like are used. In addition, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonaate and cholesteryl carbonate, and chiral agents such as those sold under the trade names "C-15" and "CB-15" (manufactured by Merck & Co.) It can also be used by adding thereto. In addition, ferroelectric liquid crystals such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate can be used. Further, as a polarizing plate used outside the liquid crystal cell, a polarizing plate in which a polarizing film called an H film absorbing iodine is sandwiched between cellulose acetate protective films while stretching and aligning polyvinyl alcohol,
Alternatively, a polarizing plate composed of the H film itself can be used.

[0046]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. The measuring method and evaluation method for the liquid crystal aligning agents prepared by the following Examples and Comparative Examples and the manufactured liquid crystal display devices are as follows.

[Surface Free Energy of Liquid Crystal Alignment Agent (Solution)] The surface free energy was measured at a temperature of 25 ° C. using a surface free energy meter (manufactured by Kyowa Interface Science Co., Ltd.) equipped with a platinum ring by a suspension ring method.

[Surface Free Energy of Thin Film] Reference "JO
URNAL OF APPLIED POLYMER
SCIENCE VOL. 13, PP. 1741-17
47 (1969) ". K. OWE
According to the method of NS et al., It was determined from the contact angle of pure water and the contact angle of methylene iodide on the thin film as follows.

In a system in which a liquid is in contact with the surface of a solid, the relationship between the surface free energy (also referred to as surface tension) of the liquid, the surface free energy of the solid, and the contact angle is given by the following equation (1). Is represented by

(Equation 2)

Here, γ _L : surface free energy of liquid γ _L ^d : dispersion component of surface free energy of liquid γ _L ^p : polar component of surface free energy of liquid γ _S ^d : dispersion component of surface free energy of solid γ _S ^p : Polar component of surface free energy of solid θ: Contact angle

Thus, at 20 ° C., for pure water, γ _L = 72.8, γ _L ^d = 21.8 and γ _L ^p =
51.0 (unit is dyn / cm). For methylene iodide, γ _L = 50.8, γ _L ^d = 49.5, and γ _L ^p = 1.3. When these values are substituted into Expression (1), Expression (2) below is obtained in the case of pure water, and Expression (3) is obtained in the case of methylene iodide. Where θ ₁
And θ ₂ are the contact angles of pure water and methylene iodide, respectively.

[0052]

(Equation 3)

Therefore, in the equations (2) and (3),
By substituting the measured value of the contact angle to obtain the gamma _S ^d and gamma _S ^p from the simultaneous equations to determine the surface free energy gamma _S of the thin film by further following formula (4).

[0054]

(Equation 4)

The contact angle was measured using a contact angle measuring device “CA-
Using Type A (manufactured by Kyowa Interface Science Co., Ltd.), 4 microliters of water or methylene iodide was dropped on the thin film, and 1
It was determined by measuring the contact angle after a lapse of minutes.

[Thickness uniformity of thin film] A liquid crystal aligning agent is applied on a substrate made of a silicone wafer by a printing method, and the substrate is dried at 180 ° C. for 1 hour. Selective stylus type film thickness meter "Alpha Step" (Tencor INS, USA)
The thickness of the thin film was measured using a TRUMENTS company, and the average value and the maximum difference (difference between the maximum film thickness and the minimum film thickness) of the thin film were determined.

[Required Amount of Liquid Crystal Alignment Agent] When a liquid crystal alignment agent is applied to a transparent substrate (10 inch square) provided with an ITO film electrode by a printing method, it is necessary to apply the liquid crystal alignment agent to the surface of 100 substrates. The amount of the liquid crystal alignment agent thus obtained was determined.

[Orientation of Liquid Crystal] The presence or absence of an abnormal domain in the liquid crystal cell when the voltage is turned on / off in the liquid crystal display element is observed with a polarizing microscope. Was determined to be "poor".

[Pretilt Angle of Liquid Crystal Display Element]
J. Schffer, et. al. , J. et al. Appl. P
hys. , Vol. 19, 2013 (1980) ", and measured by a crystal rotation method using a He-Ne laser beam.

[Reliability in long-term use (presence or absence of display defects)] High-temperature and high-humidity environment (temperature 80 ° C., relative humidity 80%)
Below, the liquid crystal display element was driven by a rectangular wave of 5 V, 60 Hz, and the presence or absence of a white spot-like display defect after 1000 hours was visually observed.

Synthesis Example 1 224.17 g of 2,3,5-tricarboxycyclopentylacetic acid dianhydride (1.00
Mol), 21.63 g of p-phenylenediamine (0.2
0 mol), 4,4'-diaminodiphenylmethane 14
8.70 g (0.75 mol) and 26.04 g (0.05 mol) of cholesteryl 3,5-diaminobenzoate in N
-Methyl-2-pyrrolidone was dissolved in 2000 g, and this solution was reacted at 50 ° C. for 6 hours. Next, the obtained reaction solution was poured into a large excess of pure water to precipitate a reaction product. Thereafter, the solid is separated, washed with pure water, and dried under reduced pressure for 4 hours.
By drying at 0 ° C. for 15 hours, the logarithmic viscosity (ηl
n) 386.9 g of 1.28 dl / g polymer (A-1)
I got

[Synthesis Example 2] 30.0 g of the polymer (A-1) obtained in Synthesis Example 1 was dissolved in 570 g of γ-butyrolactone, 33.3 g of pyridine and 25.8 acetic anhydride.
g was added and dehydration ring closure was performed at 110 ° C. for 3 hours. Next, in the same manner as in Synthesis Example 1, precipitation, separation,
By performing washing and drying, logarithmic viscosity (ηln) 1.
28.0 g of a polymer (B-1) of 31 dl / g was obtained.

[Synthesis Example 3] Instead of the tetracarboxylic dianhydride used in Synthesis Example 1, 1,3,3a, 4,4
5,9b-Hexahydro-8-methyl-5 (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,
2-c] -furan-1,3-dione 314.30 g
In the same manner as in Synthesis Example 1 except that (1.00 mol) was used, 469.8 g of a polymer (A-2) having an intrinsic viscosity (ηln) of 1.08 dl / g was obtained. Then, the polymer (A-
Except that 30.0 g of the polymer (A-2) was used in place of 1), the logarithmic viscosity (ηln) was 1.
26.9 g of a polymer (B-2) of 01 dl / g was obtained.

[Synthesis Example 4] Instead of the diamine compound used in Synthesis Example 3, p-phenylenediamine 81.1 was used.
Synthesis example except that 1 g (0.75 mol), 39.65 g (0.20 mol) of 4,4′-diaminodiphenylmethane and 26.04 g (0.05 mol) of cholesteryl 3,5-diaminobenzoate were used. Polymer (A-3) 42 having a logarithmic viscosity (ηln) of 1.18 dl / g in the same manner as in Example 3.
4.1 g were obtained. Thereafter, Synthesis Example 2 was repeated except that 30.0 g of the polymer (A-3) was used instead of the polymer (A-1).
In the same manner as in the above, 27.2 g of a polymer (B-3) having a logarithmic viscosity (ηln) of 1.11 dl / g was obtained.

[Synthesis Example 5] In place of the diamine compound used in Synthesis Example 3, p-phenylenediamine 21.6 was used.
3g (0.20 mol), 138.79 g (0.70 mol) of 4,4'-diaminodiphenylmethane and 3,5-
52.08 g of cholesteryl diaminobenzoate (0.10 g)
(A-4) 4 having a logarithmic viscosity (ηln) of 0.88 dl / g in the same manner as in Synthesis Example 3 except that (mol) was used.
84.8 g were obtained. Thereafter, logarithmic viscosity (ηln) 0.74 dl / g was obtained in the same manner as in Synthesis Example 2 except that 30.0 g of polymer (A-4) was used instead of polymer (A-1).
26.8 g of a polymer (B-4) was obtained.

[Synthesis Example 6] The same as Synthesis Example 1 except that pyromellitic dianhydride 218.12 (1.00 mol) was used in place of the tetracarboxylic dianhydride used in Synthesis Example 1. And logarithmic viscosity (ηln) 1.58 dl
/ G of polymer (A-5) 385.4 g was obtained.

[Synthesis Example 7] Instead of the diamine compound used in Synthesis Example 1, p-phenylenediamine 107.
315.7 g of a polymer (A-6) having an intrinsic viscosity (ηln) of 1.39 dl / g was obtained in the same manner as in Synthesis Example 1 except that 06 g (0.99 mol) was used.

[Synthesis Example 8] Instead of the diamine compound used in Synthesis Example 3, p-phenylenediamine 21.6 was used.
3g (0.20 mol), 118.96 g (0.60 mol) of 4,4'-diaminodiphenylmethane and 3,5-
104.16 g of cholesteryl diaminobenzoate (0.2
Polymer (A-7) having an logarithmic viscosity (ηln) of 0.68 dl / g in the same manner as in Synthesis Example 1 except that 0 mol) was used.
508.7 g were obtained. Thereafter, the logarithmic viscosity (ηln) was 0.54 dl / in the same manner as in Synthesis Example 2 except that 30.0 g of the polymer (A-7) was used instead of the polymer (A-1).
Thus, 26.5 g of a polymer (B-7) was obtained.

<Example 1> (1) Preparation of liquid crystal aligning agent: 1 g of the polymer (A-1) obtained in Synthesis Example 1 was mixed with N-methyl-2-pyrrolidone and 3-
It was dissolved in a mixed solvent with ethyl ethoxypropionate (mixing weight ratio: 60/40) to obtain a solution having a solid content of 4% by weight, and this solution was filtered through a filter having a pore size of 1 μm to prepare a liquid crystal aligning agent. The obtained liquid crystal aligning agent (solution)
Had a surface free energy of 35.2 dyn / cm.

(2) Formation of Thin Film: This liquid crystal aligning agent is applied to the transparent electrode surface of a glass substrate provided with a transparent electrode made of an ITO film using a printing machine for applying an aligning agent. A thin film was formed by drying on a plate for 20 minutes. The average value of the film thickness of this thin film is 500 °, the maximum thickness difference is 15 °,
The film had excellent film thickness uniformity. The surface free energy of this thin film was 45.3 dyn / cm.

(3) Formation of liquid crystal alignment film: The surface of the formed thin film is subjected to a rubbing treatment using a rubbing machine having a roll around which a cloth made of rayon is wound, so that the alignment ability of the liquid crystal molecules is reduced. It was applied to a thin film to form a liquid crystal alignment film. Here, the rubbing treatment conditions were as follows: the number of rotations of the roll was 500 rpm, and the moving speed of the stage was 1 cm /
Seconds, the length of the pressed foot was 0.4 mm.

(4) Production of liquid crystal display element: Two substrates on which a liquid crystal alignment film was formed as described above were produced, and an epoxy resin containing aluminum oxide spheres having a diameter of 17 μm on the outer edge of each substrate. Is applied by a screen printing method, and two substrates are opposed to each other with a gap therebetween so that the rubbing directions of the respective liquid crystal alignment films are antiparallel. Was cured. Next, a nematic liquid crystal “ZLI-5080” (manufactured by Merck) is injected and filled into the cell gap defined by the adhesive on the surface of the substrate and the outer edge, and the injection hole is sealed with an epoxy adhesive. Thus, a liquid crystal cell was formed. Next, a polarizing plate is attached to the outer surface of the liquid crystal cell, that is, the other surface of each substrate constituting the liquid crystal cell, such that the polarization direction matches the rubbing direction of the liquid crystal alignment film formed on one surface of the substrate. Thus, a liquid crystal display element was manufactured.

(5) Evaluation of liquid crystal display element: The liquid crystal display element produced as described above was examined for liquid crystal orientation. When the voltage was turned on and off, abnormal domains were found in the liquid crystal cell. It was confirmed that the composition had excellent orientation. In addition, the pretilt angle of this liquid crystal display element was as high as 5.3 °, and white stain-like display defects were not observed even after long-term use under high temperature and high humidity, which was highly reliable. .

<Examples 2 to 10> Each of the polymers A and B shown in Table 1 was dissolved in each of the mixed solvents having the compositions shown in Table 1 to obtain a solution having a solid concentration of 4% by weight. In the same manner as in Example 1 except that this solution was used, a liquid crystal alignment agent of the present invention was prepared, a thin film was formed on a substrate, and a rubbing treatment was performed on the thin film to form a liquid crystal alignment film. A liquid crystal display device including the liquid crystal alignment film was manufactured.

Comparative Examples 1 to 6 Polymers A and B shown in Table 2 were each dissolved in each of the mixed solvents having the compositions shown in Table 2 to obtain a solution having a solid content of 4% by weight. A liquid crystal alignment agent for comparison was prepared in the same manner as in Example 1 except that this solution was used, a thin film was formed on a substrate, and a rubbing process was performed on the thin film to form a liquid crystal alignment film. A liquid crystal display device including the liquid crystal alignment film was manufactured.

The surface free energy of each of the liquid crystal aligning agents (solutions) prepared in Examples 1 to 10 and Comparative Examples 1 to 6, the surface free energy of the formed thin film, the film thickness uniformity of the thin film, Measurement results and evaluation results are shown in Tables 1 and 2 for the required coating amount of the liquid crystal alignment agent, the liquid crystal alignment property of the manufactured liquid crystal display element, the pretilt angle, and the presence or absence of display defects during long-term use.

In Tables 1 and 2, the types of the solvents (a) to (e) constituting the mixed solvent are as follows. Solvent (a): N-methyl-2-pyrrolidone Solvent (b): ethyl 3-ethoxypropionate Solvent (c): ethylene glycol monohexyl ether Solvent (d): γ-butyrolactone Solvent (e) ： Ethylene glycol butyl ether

[0078]

[Table 1]

[0079]

[Table 2]

<Relationship between Surface Free Energy of Liquid Crystal Alignment Agent (Solution) and Uniformity of Film Thickness> Examples 3 to 5 and Comparative Example 3
FIG. 1 shows the relationship between the surface free energy of the liquid crystal aligning agent (solution) and the thickness uniformity of the formed thin film for the liquid crystal aligning agents prepared in Nos. 1 to 4. Each of the liquid crystal alignment agents according to the above Examples and Comparative Examples is prepared by dissolving the polymer (A-1) in a mixed solvent of the solvent (a) and the solvent (c), and has a surface free energy of Is 45.3 dy
It forms a thin film of n / cm. As shown in FIG. 1, a remarkable difference was observed between the liquid crystal aligning agents according to Examples 3 to 5 and the liquid crystal aligning agents according to Comparative Examples 3 and 4 with respect to the effect of uniformity of the thickness of the formed thin film. Can be

Further, Examples 1 to 10 and Comparative Examples 1 to
FIG. 2 shows the relationship between the surface free energy of the liquid crystal aligning agent (solution) and the thickness uniformity of the formed thin film for the liquid crystal aligning agent prepared in 4 above. As shown in FIG. 2, by controlling the surface free energy of the liquid crystal aligning agent (solution) to a specific range (more than 30 dyn / cm and less than 38 dyn / cm), regardless of the type of the polymer and the type of the solvent. A remarkable effect of uniformity of film thickness is recognized.

[0082]

According to the method for forming a liquid crystal alignment film of the present invention, a thin film having a high uniformity of the film thickness can be formed even when the amount of the liquid crystal alignment agent applied to the substrate is small, resulting in excellent display. A liquid that can exhibit properties in a liquid crystal display device
A crystalline orientation film is obtained. Further, formation of the liquid crystal alignment film of the present invention
According to the method , a liquid crystal alignment film having excellent liquid crystal alignment properties can be formed, and a high pretilt angle can be exhibited in a liquid crystal display device. Further, the method of the present invention
According to such a liquid crystal alignment film , a display defect does not occur in the liquid crystal display element even after long-term use, and the liquid crystal display element can exhibit high reliability.

The liquid crystal alignment film formed by the method of the present invention can be used not only for TN type liquid crystal display devices but also for STN (Super
(Twisted Nematic) type liquid crystal display element,
SH (Super Homeotropic) type liquid crystal display device, IPS (In-Plane-Switchin)
It can be suitably used for forming various liquid crystal display elements such as a g) type liquid crystal display element, a ferroelectric liquid crystal display element, and an antiferroelectric liquid crystal display element. In addition, a liquid crystal display device provided with the liquid crystal alignment film has excellent liquid crystal alignment and reliability, and can be effectively used for various devices.
For example, it can be suitably used as a display device such as a desk calculator, a wristwatch, a clock, a counting display, a word processor, a personal computer, and a liquid crystal television.

[Brief description of the drawings]

FIG. 1 shows the relationship between the surface free energy of a liquid crystal aligning agent (solution) and the thickness uniformity of a formed thin film for liquid crystal aligning agents prepared in Examples 3 to 5 and Comparative Examples 3 and 4. It is a graph.

FIG. 2 shows the relationship between the surface free energy of a liquid crystal aligning agent (solution) and the thickness uniformity of a formed thin film for the liquid crystal aligning agents prepared in Examples 1 to 10 and Comparative Examples 1 to 4. It is a graph.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeo Kawamura 2--11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (72) Inventor Yasuo Matsuki 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (56) References JP-A-63-178213 (JP, A) JP-A-59-121023 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1 / 1337

Claims (2)

(57) [Claims] 1. A surface containing at least one polymer selected from a polyamic acid and an imidized polymer thereof.
Free energy exceeds 30 dyn / cm and 38 dyn
/ Cm or less solution of liquid crystal aligning agent and dry
As a result, the surface free energy becomes 38 dyn / cm
Exceeds 50 dyn / cm, the maximum thickness difference
Liquid crystal alignment characterized by forming a thin film of 25 ° or less
Method of forming a film. 2. Formed by the method of claim 1.
Liquid crystal alignment film in which alignment ability is imparted to a thin film.
A liquid crystal display device characterized by the following.