JP3211664B2 - Liquid crystal alignment agent and liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a liquid crystal aligning agent and a liquid
The present invention relates to a crystal display element . More specifically, a liquid crystal aligning agent which has good liquid crystal alignment and a high pretilt angle and
And a liquid crystal display device .

[0002]

2. Description of the Related Art Conventionally, a sandwich structure is formed by forming a layer of a nematic liquid crystal having a positive dielectric anisotropy between two substrates having a liquid crystal alignment film formed on the surface thereof through a transparent conductive film. TN in which the major axis of the liquid crystal molecules is continuously twisted by 90 degrees from one substrate to the other substrate.
2. Description of the Related Art A TN liquid crystal display device having a (Twisted Nematic) liquid crystal cell is known. Orientation of the liquid crystal in the TN type liquid crystal display device or the like is usually realized by a liquid crystal alignment film provided with an alignment ability of liquid crystal molecules by a rubbing process. Here, as a material for the liquid crystal alignment film, resins such as polyimide, polyamide, and polyester have been conventionally known. In particular, polyimide is excellent in heat resistance, affinity with liquid crystal, and mechanical strength. It is used in many liquid crystal display devices.

[0003]

However, when a conventionally known liquid crystal alignment film made of polyimide or the like is formed to manufacture a TN type liquid crystal display device or the like, display defects are caused due to a low pretilt angle of the liquid crystal display device. There is a problem that occurs. For this reason, development of a liquid crystal aligning agent capable of providing a liquid crystal display element having a good liquid crystal alignment property and a high pretilt angle is desired. The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide a liquid crystal aligning agent capable of obtaining a liquid crystal alignment film having good liquid crystal alignment. . A second object of the present invention is to provide a liquid crystal aligning agent capable of obtaining a high pretilt angle. Still other objects and advantages of the present invention will become apparent from the following description.

[0004]

SUMMARY OF THE INVENTION The above objects and advantages of the present invention are as follows: a polyamic acid and an imidized polymer having a structure obtained by dehydrating and ring-closing a polyamic acid and having two different imidization rates. A liquid crystal aligning agent containing the above polymer, the polymer contained in the liquid crystal aligning agent, the larger the imidation rate, the more its surface
This is achieved by a liquid crystal aligning agent characterized by being a polymer having a low free energy . The effect of the liquid crystal aligning agent of the present invention is that there is little afterimage .

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polymer used in the liquid crystal aligning agent of the present invention is prepared by reacting a tetracarboxylic dianhydride and a diamine compound described below in an organic solvent to synthesize a polyamic acid, and further dehydrating the polyamic acid as necessary. It can be obtained by ring closure.

[Tetracarboxylic dianhydride] Examples of the tetracarboxylic dianhydride used in the synthesis of the polyamic acid include butanetetracarboxylic dianhydride and
1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dichloro-1,
2,3,4-cyclobutanetetracarboxylic dianhydride,
1,2,3,4-cyclopentanetetracarboxylic dianhydride, 1,2,4,5-cyclohexanetetracarboxylic dianhydride, 3,3 ′, 4,4′-dicyclohexyltetracarboxylic dianhydride 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5
-Tetrahydrofurantetracarboxylic dianhydride, 5-
(2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, bicyclo [2,2,2] -oct-7-ene-2,
Aliphatic and cycloaliphatic tetracarboxylic dianhydrides such as 3,5,6-tetracarboxylic dianhydride;

1,3,3a, 4,5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] furan-1,3-dione, , 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- Aliphatic tetracarboxylic dianhydride having an aromatic ring, such as 1,3-dione, a compound represented by the following formula (I), and a compound represented by the following formula (II);

[0008]

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(Wherein, R ¹ and R ^{3 each} represent a divalent organic group having an aromatic ring, R ² and R ^{4 each} represent a hydrogen atom or an alkyl group, and a plurality of R ² and R ⁴ represent , May be the same or different.)

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), 3,6-
Aromatic tetracarboxylic dianhydrides such as bis (anhydrotrimellitate) cholestane, the following formulas (1) to (4)
And aromatic tetracarboxylic dianhydrides such as the compounds represented by These may be used alone or in combination.
Used in combination of more than one species.

[0011]

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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-8-
Methyl-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, 1,3
3a, 4,5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,
R> 2-c] furan-1,3-dione, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl Sulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, the following formulas (5) to
The compound represented by the formula (7) and the compound represented by the following formula (8) are preferable from the viewpoint that good liquid crystal alignment can be exhibited.
3,4-cyclobutanetetracarboxylic dianhydride, 1,
3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic 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-
Examples thereof include 1,3-dione, pyromellitic dianhydride and a compound represented by the following formula (5).

[0013]

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[Diamine compound] The diamine compound used for the synthesis of the polyamic acid includes, for example, p-
Phenylenediamine, m-phenylenediamine, 4,
4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,5-diaminobenzoic acid, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylsulfone, 4, 4'-diaminodiphenyl ether, 4,4 '
-Diaminodiphenyl sulfide, 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, 4,4′-diaminobenzanilide, 3,4 ′
-Diaminodiphenyl ether, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone,
4,4'-diaminobenzophenone, 2,7-diaminofluorene, 2,2-bis (4-aminophenyl) hexafluoropropane, 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, 4,4'-diamino-2,2'-bis (trifluoromethyl) biphenyl, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] sulfone, 1,4-bis (4-aminophenoxy) benzene , 4,4'-bis (4-aminophenoxy) -biphenyl, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9-bis (4 Aminophenyl)
-10-hydroanthracene, 9,9-bis (4-aminophenyl) fluorene, 4,4 '-(p-phenylenediisopropylidene) bisaniline, 4,4'-(m-
Phenylenediisopropylidene) bisaniline, 2,
2′-bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl] hexafluoropropane,
Aromatic diamines such as 4,4′-bis [(4-amino-2-trifluoromethyl) phenoxy] -octafluorobiphenyl;

An aromatic diamine having two amino groups bonded to an aromatic ring such as diaminotetraphenylthiophene and a hetero atom other than a nitrogen atom of the amino group;

1,1-meta-xylylenediamine, 1,3
-Bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, 1,2-ethylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylene Diamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane,
1,2-diaminocyclohexane, 1,3-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7
-Methanoindanylene dimethylene diamine, tricyclo [6,2,1,02.7] -undecylenedimethyl diamine, 4,4'-methylene bis (cyclohexylamine)
Aliphatic or alicyclic diamines such as 1,1-methaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylenediethylenediamine, tricyclo [6,
2,1,02.7] -undecylenedimethyldiamine,
Aliphatic and cycloaliphatic diamines such as 4,4'-methylenebis (cyclohexylamine);

A monosubstituted phenylenediamine represented by the following formula (III); a diaminoorganosiloxane represented by the following formula (IV):

[0018]

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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. )

[0020]

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(Wherein R ⁷ represents a hydrocarbon group having 1 to 12 carbon atoms, a plurality of R ^{7 s} may be the same or different, p is an integer of 1 to 3, and q is 1-2
It is an integer of 0. )

Examples include compounds represented by the following formulas (9) to (13). These diamine compounds can be used alone or in combination of two or more.

[0023]

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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,
m-phenylenediamine, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 3,
3′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfide, 1,5-diaminonaphthalene,
2,7-diaminofluorene, 4,4′-diaminodiphenyl ether, 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-phenylenediisopropylidene) bisaniline, 2,2-bis [4- (4
-Aminophenoxy) phenyl] sulfone, 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 4,4'-methylenebis (cyclohexylamine), 1,4-bis (4-aminophenoxy) benzene, 4,4 ' -Bis (4-aminophenoxy) -biphenyl, m-xylylenediamine, the above formulas (9) to (1)
The compound represented by 3) and the compounds represented by the following formulas (14) to (18) are preferable.

[0026]

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[Polyamic acid] The ratio of the tetracarboxylic dianhydride and the diamine compound used in the synthesis reaction of the polyamic acid is such that the ratio of the tetracarboxylic dianhydride to the equivalent of the amino group contained in the diamine compound is 1 equivalent. The ratio in which the amount of the acid anhydride group is 0.2 to 2 equivalents is preferable, and the ratio is more preferably 0.3 to 1.2 equivalents. The synthesis reaction of the polyamic acid is usually performed in an organic solvent at 0 to 150 ° C.
The reaction is preferably performed at a reaction temperature of 0 to 100 ° C for 1 to 48 hours. The organic solvent is not particularly limited as long as it can dissolve the reactant generated in the reaction. For example, aprotic polar solvents such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide; Phenolic solvents such as cresol, xylenol, phenol and halogenated phenol can be mentioned. 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 organic solvents include alcohols, ketones, esters which are poor solvents for polyamic acid,
Ethers, halogenated hydrocarbons, hydrocarbons and the like can be used in combination as long as the generated polyamic acid does not precipitate. 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, diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl 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 Lumpur ethyl ether acetate, 4
-Hydroxy-4-methyl-2-pentanone, ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl 2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate, 2- Methyl hydroxy-3-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-ethoxy Butanol, 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,
Examples include toluene and xylene. These may be used alone or in combination of two or more.

By the above synthesis reaction, a reaction solution obtained by dissolving the polyamic acid is obtained. Then, 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 polyamic acid. Further, the polyamic acid can be purified by dissolving the polyamic acid in an organic solvent again and then performing the step of precipitating with a poor solvent once or several times.

[Imidated polymer] The imidized polymer constituting the liquid crystal aligning agent of the present invention can be prepared by subjecting the above polyamic acid to dehydration and ring closure. The dehydration and ring closure of the polyamic acid can be performed by (i) heating the polyamic acid or (ii) dissolving the polyamic acid in an organic solvent, adding a dehydrating agent and a dehydration ring-closing catalyst to the solution, and heating as necessary. Done by the method.

The reaction temperature in the method (i) for heating a polyamic acid is usually 50 to 200 ° C., preferably 60 to 170 ° C. When the reaction temperature is lower than 50 ° C., the dehydration ring closure reaction does not proceed sufficiently, and the reaction temperature is lower than 20 ° C.
If it exceeds 0 ° C., the molecular weight of the obtained imidized polymer may decrease. On the other hand, in the above method (ii) of adding a dehydrating agent and a dehydration ring-closing catalyst to a solution of a polyamic acid, an acid anhydride such as acetic anhydride, propionic anhydride, or trifluoroacetic anhydride is used as the dehydrating agent. Can be. 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. As the dehydration ring-closing catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, and triethylamine can be used. However, it is not limited to these. 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, as the organic solvent used for the dehydration ring closure reaction, the organic solvents exemplified as those used for the synthesis of polyamic acid can be exemplified. The reaction temperature of the dehydration ring closure reaction is usually 0 to 180 ° C, preferably 10 ° C.
１５０150 ° C. The imidized polymer can be purified by subjecting the reaction solution thus obtained to the same operation as the method for purifying a polyamic acid.

[Imidation rate of polymer] The imidation rate of the polymer used in the liquid crystal aligning agent of the present invention can be arbitrarily adjusted by controlling the amount of the catalyst, the reaction time and the reaction temperature. Here, “imidation rate” in the present specification
Is defined as a percentage of the number of repeating units forming an imide ring or an isoimide ring with respect to the total number of repeating units in the polymer, and in this specification, a polyamic acid which does not undergo a dehydration ring-closing reaction Is 0%. The imidation ratio of each polymer is determined by dissolving the polymer in deuterated dimethyl sulfoxide, measuring ¹ H-NMR at room temperature using tetramethylsilane as a reference substance, and calculating by the formula shown by the following formula (1). Things.

[0033]

## EQU1 ## Imidation rate (%) = (1-A ¹ / A ² × α) × 100 (1) A ¹ : Peak area derived from proton of NH group (10 ppm)
A ² ): Peak area derived from other protons α: N in polymer precursor (polyamic acid)
Number ratio of other protons to one proton of H group

[Terminal-modified type polymer] The polymer constituting the liquid crystal aligning agent of the present invention may be a terminal-modified type 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 polyamic acid. Here, as the acid monoanhydride, for example, maleic anhydride, phthalic anhydride, itaconic anhydride, n-decylsuccinic anhydride, n-dodecylsuccinic anhydride, n-tetradecylsuccinic anhydride , N-
Hexadecyl succinic anhydride may be mentioned. Examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine, and n-butylamine.
Pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine,
n-pentadecylamine, n-hexadecylamine, n
-Heptadecylamine, n-octadecylamine, n-
Eicosylamine and the like can be mentioned. 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) value 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. It is obtained by the equation shown in (2).

[0036]

(Equation 2)

[Liquid Crystal Alignment Agent] The liquid crystal alignment agent of the present invention comprises two or more polymers having different imidization ratios dissolved in an organic solvent. The two or more polymers in the liquid crystal alignment agent of the present invention have a correlation between the degree of imidization and the degree of surface free energy of the polymer, and the higher the degree of imidization, the higher the surface free energy of the polymer. Is small ,
It has the characteristic that the afterimage is small. In the two or more polymers constituting the liquid crystal aligning agent of the present invention, the difference in the imidation ratio between the polymer having the largest imidization ratio and the polymer having the smallest imidation ratio is preferably 5% or more, and particularly preferably 10%. As described above, the average imidation ratio of the entire polymer in each liquid crystal alignment agent is preferably 50% or more. The surface free energy of the liquid crystal alignment film obtained by the liquid crystal alignment agent of the present invention is preferably 40 to 60 dyn / cm.

The content ratio of the polymer in the liquid crystal aligning agent of the present invention is selected in consideration of viscosity, volatility, etc., but is preferably 0.1 to 20% by weight based on the whole liquid crystal aligning agent.
More preferably, it is in the range of 1 to 10% by weight. That is, the liquid crystal alignment agent composed of the weight solution is applied to the substrate surface by a printing method, a spin coating method, and the like, and then dried to form a coating film as an alignment film material. If the content of the polymer is less than 0.1% by weight, the thickness of the coating film may be too small to obtain a good liquid crystal alignment film, and if it exceeds 20% by weight. In some cases, it is difficult to obtain a good liquid crystal alignment film due to an excessively large thickness of the coating film, and the viscosity of the liquid crystal alignment agent may be increased, resulting in poor coating characteristics. The organic solvent for dissolving the polymer is not particularly limited as long as it can dissolve the polymer, and examples thereof include the solvents exemplified as those used in the synthesis reaction of polyamic acid and the dehydration ring closure reaction. . In addition, the poor solvents exemplified as those which can be used together in the synthesis reaction of the polyamic acid can be appropriately selected and used in combination.

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 between the polymer and the surface of the substrate to be coated. Such functional silane-containing compounds include, for example, 3-aminopropyltrimethoxysilane, 3
-Aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl)
-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltrimethoxysilane, 3-ureidopropyltriethoxysilane, N-ethoxycarbonyl-3
-Aminopropyltrimethoxysilane, N-ethoxycarbonyl-3-aminopropyltriethoxysilane, N
-Triethoxysilylpropyltriethylenetriamine, N-trimethoxysilylpropyltriethylenetriamine, 10-trimethoxysilyl-1,4,7-triazadecane, 10-triethoxysilyl-1,4,7-triazadecane, 9-tri Methoxysilyl-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-aminopropyltrimethoxysilane Ethoxysilane, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, N
-Bis (oxyethylene) -3-aminopropyltriethoxysilane and the like. 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 and the like can be mentioned as preferable ones. 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 obtained by using the liquid crystal aligning agent of the present invention can be produced, 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 ₂ , or the like can be used. A photo-etching method, a method using a mask in advance, or the like is used for patterning these transparent conductive films. In applying the liquid crystal alignment 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 coating film. it can. 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 is wound, so that the film is provided with the ability to align liquid crystal molecules. Becomes In addition to the method using a rubbing treatment, a method of irradiating polarized ultraviolet light to the coating surface to impart orientation ability, a uniaxial stretching method, a Langmuir method,
The liquid crystal alignment film can also be formed by a method of obtaining a film by a blow jet method or the like. 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. Also,
For example, JP-A-6-222366 and JP-A-6-281 disclose a liquid crystal alignment film formed by the liquid crystal alignment agent of the present invention.
No. 937, a process in which the pretilt angle is changed by partially irradiating ultraviolet rays, or a rubbed liquid crystal, as described in JP-A-5-107544. After partially forming a resist film on the alignment film, performing a rubbing process in a direction different from the preceding rubbing process, removing the resist film, and performing a process of changing the alignment ability of the liquid crystal alignment film. By doing so, it is possible to improve the visibility characteristics of the liquid crystal display element.

(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, 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. In addition, the polarizing plate used outside the liquid crystal cell includes a polarizing plate or a H film itself in which a polarizing film called an H film that absorbs iodine and sandwiched by a cellulose acetate protective film while stretching and aligning polyvinyl alcohol is used. A polarizing plate and the like can be given.

[0043]

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 evaluation method for each liquid crystal display device manufactured by the following Examples and Comparative Examples is described below.

[Surface Free Energy of Polymer and Liquid Crystal Alignment Film] Each polymer was dissolved in N-methyl-2-pyrrolidone, applied on a silicon wafer by spin coating, and heated at 100 ° C. for 3 hours. A thin film was formed.
Then, the document "JOURNAL OF APPLIED"
POLYMER SCIENCE VOL. 13, P
P. 1741-1747 (1969). K. According to the method of OWENS et al., From the contact angle of pure water and the contact angle of methylene iodide on the thin film and the liquid crystal alignment film obtained in each example, the surface free energy of the polymer and the liquid crystal alignment film was determined as follows. I asked. In a system where a liquid is in contact with the surface of a solid,
The relationship between the surface free energy of the liquid (also referred to as surface tension), the surface free energy of the solid, and the contact angle is represented by the following equation (3).

[0045]

Equation 3] _{(1 + cosθ) × γ L} = 2 (γ s d × γ L d) 1/2 +2 (γ s p × γ L p) 1/2 ··· (3) γ L: the free surface of the liquid Energy 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

Under the condition of 20 ° C., for pure water, γ _L = 72.8, γ _L ^d = 21.8 and γ _L ^p = 5
1.0 (all units are dyn / cm), and for methylene iodide, γ _L = 50.8 and γ _L ^d = 49.5.
And γ _L ^p = 1.3. When these values are substituted into Expression (3), the following Expression (4) is obtained in the case of pure water, and the following Expression (5) is obtained in the case of methylene iodide. Here, θ ₁ and θ ₂ are the contact angles of pure water and methylene iodide, respectively.

[0047]

(1 + cos θ ₁ ) × 72.8 = 2 (γ _s ^d × 21.8) ^1/2 +2 (γ _s ^p × 51.0) ^1/2 (4) (1 + cos θ ₂ ) × 50.8 = 2 (γ _s ^d × 49.5) ^1/2 +2 (γ _s ^p × 1.3) ^1/2・ ・ ・ (5)

Therefore, the above equations (4) and (5)
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 film by further following formula (6).

[0049]

Γ _S = γ _S ^d + γ _S ^p (6) The contact angle was measured using water or a contact angle measuring device “CA-A” (manufactured by Kyowa Interface Science Co., Ltd.). 4 microliters of methylene iodide was dropped on the film, and the contact angle after 1 minute was measured.

[Orientation of Liquid Crystal] The presence or absence of abnormal domains in the liquid crystal cell when the voltage was turned on / off in the liquid crystal display element was observed with a polarizing microscope, and the case where there was no abnormal domain was judged as “good”. [Pretilt Angle of Liquid Crystal Display Element] The pretilt angle of the liquid crystal display element is described in [TJ Schffer et al., J. Appl. Phys., 1
9, 2013 (1980)], and measured by a crystal rotation method using He-Ne laser light. [Uniformity of coating film] The average film thickness of the coating film and the difference between the maximum film thickness value and the minimum film thickness value (hereinafter referred to as "maximum difference") are measured using a stylus-type film thickness meter. ). [Residual voltage of liquid crystal display element] A DC voltage of 5 V was applied to the liquid crystal display element under a temperature condition of 80 ° C for 2 hours, and after applying the voltage, the maximum voltage remaining in the liquid crystal display element was measured. .

Synthesis Example 1 224.17 g (1.00 mol) of 2,3,5-tricarboxycyclopentylacetic acid dianhydride, 102.73 g (0.95 mol) of p-phenylenediamine and 3,5-
26.04 g of cholesteryl diaminobenzoate (0.05
Mol) was dissolved in 2000 g of N-methyl-2-pyrrolidone, and this solution was reacted at 50 ° C. for 6 hours. Then
The obtained reaction solution was poured into a large excess of pure water to precipitate a reaction product. After that, the solid is separated and washed with pure water,
By drying at 40 ° C. under reduced pressure for 15 hours, a polymer (A- having a logarithmic viscosity (ηln) of 1.31 dl / g, an imidation ratio of 0%, and a surface free energy of 52.2 dyn / cm) was obtained.
1) 335.3 g was obtained. Synthesis Example 2 30.0 g of the polymer (A-1) obtained in Synthesis Example 1 was used in γ-
Dissolved in 570 g of butyrolactone, 33.3 pyridine
g and 25.8 g of acetic anhydride were added thereto, followed by dehydration and ring closure at 110 ° C. for 3 hours. Then, in the same manner as in Synthesis Example 1, by precipitating, separating, washing and drying the reaction product,
Logarithmic viscosity (ηln) 1.33 dl / g, imidization ratio 95
%, And 28.0 g of a polymer (A-2) having a surface free energy of 44.6 dyn / cm was obtained. Synthesis Example 3 Except that 13.3 g of pyridine and 17.2 g of acetic anhydride were used, the logarithmic viscosity (ηln) was 1.
13 dl / g, imidization ratio 80%, surface free energy
27.8 g of a polymer (A-3) having 45.9 dyn / cm was obtained. Synthesis Example 4 Logarithmic viscosity (ηln) 0.86 in the same manner as in Synthesis Example 1 except that 6.7 g of pyridine and 8.6 g of acetic anhydride were used.
dl / g, imidation ratio 45%, surface free energy 4
27.5 g of a polymer (A-4) having 8.8 dyn / cm was obtained.

Synthesis Example 5 The logarithm was obtained in the same manner as in Synthesis Example 1 except that 21.12 g (0.05 mol) of the compound represented by the above formula (14) was used instead of cholesteryl 3,5-diaminobenzoate. Polymer (B-1) having a viscosity (ηln) of 1.18 dl / g, an imidization ratio of 0%, and a surface free energy of 50.2 dyn / cm.
330.6 g were obtained. Thereafter, Synthesis Example 2 was repeated except that 30.0 g of the polymer (B-1) was used instead of the polymer (A-1).
Logarithmic viscosity (ηln) 1.07 dl / g,
Imidation ratio 93%, surface free energy 43.8 dyn
/ Cm of polymer (B-2) was obtained. Synthesis Example 6 Polymer (B-1) 30.0 g instead of polymer (A-1)
Was used in the same manner as in Synthesis Example 3 except that the logarithmic viscosity (ηl
n) Polymer (B-3) 2 having 0.89 dl / g, an imidation ratio of 82%, and a surface free energy of 44.6 dyn / cm.
6.7 g were obtained.

Synthesis Example 7 1,3,3a, 4,5,9b-Hexahydro-8-methyl-5- (tetrahydro-2,5-dioxo) was replaced with 2,3,5-tricarboxycyclopentylacetic acid dianhydride -3-furanyl) -naphtho [1,2-c] furan-1,
Except that 314.30 g (1.00 mol) of 3-dione was used, the logarithmic viscosity (ηln) was 1.0 in the same manner as in Synthesis Example 1.
2 dl / g, imidation ratio 0%, surface free energy 5
420.9 g of a polymer (C-1) of 0.1 dyn / cm was obtained. Then, instead of the polymer (A-1), the polymer (C-
1) In the same manner as in Synthesis Example 2 except that 30.0 g was used,
Logarithmic viscosity (ηln) 0.86 dl / g, imidization ratio 99
% Of a polymer (C-2) having a surface free energy of 42.2 dyn / cm was obtained.

Synthesis Example 8 218.12 g (1.00 mol) of pyromellitic dianhydride as tetracarboxylic dianhydride and 108.14 g (1.00 mol) of p-phenylenediamine as diamine compound
(E-1) in the same manner as in Synthesis Example 1 except that the polymer (E-1) had a logarithmic viscosity (ηln) of 1.89 dl / g, an imidation ratio of 0%, and a surface free energy of 57.2 dyn / cm.
313.0 g were obtained.

Synthesis Example 9 1,3-dimethyl-tetracarboxylic dianhydride
224.17 g (1.00 mol) of 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 410.52 g of 2,2-bis [4- (4-aminophenoxy) phenyl] propane as a diamine compound ( Logarithmic viscosity (ηln) in the same manner as in Synthesis Example 1 except that 1.00 mol) was used.
Polymer (G-1) 603.0 having 1.59 dl / g, imidation ratio of 0%, and surface free energy of 53.3 dyn / cm.
g was obtained.

Synthesis Example10 2,3,5-trical as tetracarboxylic dianhydride
Boxycyclopentylacetic dianhydride 224.17g
(1.00 mol), p-phenylene as a diamine compound
108.14 g (1.00 mol) of diamine
Other than the above, the logarithmic viscosity (ηln) is 1.6 in the same manner as in Synthesis Example 1.
315.7 g of a polymer (H-1) of 9 dl / g was obtained. So
After that, the polymer (H-1) 3 was used instead of the polymer (A-1).
Logarithmic viscosity was obtained in the same manner as in Synthesis Example 2 except that 0.0 g was used.
Degree (ηln) 1.70 dl / g, imidization rate 95%, table
Polymer having a surface free energy of 57.5 dyn / cm (H-
2) 28.4gObtained.

[0057] Example 1 (1) the polymer obtained in Preparation Synthesis Example 1 of the liquid crystal aligning agent (A-1) 2.5 g and if
2.5 g of the polymer (A-2) obtained in Example 2 was dissolved in N-methyl-2-pyrrolidone to obtain a solution having a solid concentration of 4% by weight, and this solution was filtered through a filter having a pore size of 1 μm. A liquid crystal aligning agent was prepared.

(2) Preparation of Liquid Crystal Display Element The liquid crystal alignment agent of the present invention was formed on a transparent conductive film made of an ITO film provided on one surface of a glass substrate having a thickness of 1 mm by using a printing machine for coating a liquid crystal alignment film. And dried at 180 ° C. for 1 hour to form a coating film. When the uniformity of this coating film was evaluated, the average film thickness was 489 ° and the maximum range was 1
It was 7Å. The formed coating film surface was subjected to a rubbing treatment using a rubbing machine having a roll around which a cloth made of rayon was wound, so that the alignment ability of liquid crystal molecules was imparted to the coating film to prepare 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.
/ Sec. Two substrates on each of which the liquid crystal alignment film was formed as described above were prepared, and an epoxy resin containing aluminum oxide spheres having a diameter of 17 μm was screen-printed and applied to the outer edge of each substrate. The two substrates were opposed to each other with a gap between them so that the rubbing directions were orthogonal or antiparallel, and the outer edges were brought into contact with each other and pressed to cure the adhesive. The nematic liquid crystal “MLC-200” is placed in the cell gap defined by the adhesive on the surface of the substrate and the outer edge.
1 "(Merck Japan Ltd.)
The injection hole was sealed with an epoxy adhesive to form a liquid crystal cell. Thereafter, a polarizing plate was attached to the outer surface of the liquid crystal cell so that the polarization direction coincided with the rubbing direction of the liquid crystal alignment film formed on one surface of the substrate, thereby producing a liquid crystal display device. When the orientation of the liquid crystal and the pretilt angle of the obtained liquid crystal display device were evaluated, the orientation of the liquid crystal was good, and the pretilt angle was a high value of 4.3 °. Table 1 shows the results.

[0059]

[0060]

Examples 2 to 9 According to the formulation shown in Table 1 , each of the polymers obtained in Synthesis Examples 1 to 10 was used to prepare the liquid crystal aligning agent of the present invention in the same manner as in Example 1 (1). Prepared. Next, using each of the liquid crystal aligning agents thus obtained, Example 1 was used.
A liquid crystal display device was produced in the same manner as in (2). In each example, the orientation, pretilt angle, and residual voltage of the liquid crystal in the liquid crystal display device were evaluated. The results are shown in Table 1 .

[0062]

[Table 1]

Comparative Examples 1 to 5 According to the formulations shown in Table 2 , using each of the polymers obtained in Synthesis Examples 1 to 10 , a liquid crystal aligning agent for comparison was prepared in the same manner as in Example 1 (1). . Next, using each of the liquid crystal aligning agents thus obtained, Example 1 was used.
A liquid crystal display device was produced in the same manner as in (2). In each comparative example, the uniformity of the coating film, the orientation of the liquid crystal in the liquid crystal display device, the pretilt angle, and the residual voltage were evaluated. The results are shown in Table 2 .

[0064]

[Table 2]

[0065]

According to the present invention, it is possible to obtain a liquid crystal aligning agent having a small afterimage of a liquid crystal display element and a high pretilt angle. A liquid crystal display device having a liquid crystal alignment film formed using the liquid crystal alignment agent of the present invention includes a TN type liquid crystal display device,
By selecting the liquid crystal to be used, the IPS (InPl
ane Switching) type, STN (Super)
Twisted Nematic type, SH (SUPE)
r Homeotropic), ferroelectric and antiferroelectric liquid crystal display devices and the like. Further, a liquid crystal display device having a liquid crystal alignment film formed using the liquid crystal alignment agent of the present invention has excellent liquid crystal alignment and reliability, and can be effectively used for various devices, for example, a desk calculator, a wrist watch, a table clock, Used for display devices such as coefficient display boards, word processors, personal computers, and liquid crystal televisions.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsukasa Toshima 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-6-51316 (JP, A) JP-A-62-165628 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1 / 1337 525

Claims (5)

(57) [Claims] 1. A liquid crystal aligning agent comprising two or more polymers having different imidation rates selected from the group consisting of a polyamic acid and an imidized polymer having a structure obtained by dehydration and ring closure of a polyamic acid. The higher the imidization ratio of the polymer contained in the liquid crystal alignment agent, the higher the polymer.
A liquid crystal aligning agent, characterized in that it is a polymer having a small surface free energy . 2. The surface free energy of a liquid crystal alignment film to be formed.
Gyr is 40-60 dyn / cm
The liquid crystal aligning agent according to claim 1 . 3. The polyamic acid is selected from the group consisting of the following compounds:
Selected tetracarboxylic dianhydride and diamine compound
Characterized by being obtained by reacting
The liquid crystal aligning agent according to claim 1 or claim 2. [Compound Group] 1,2,3,4-cyclobutanetetracarboxylic dianhydride
Objects, 1,3-dimethyl-1,2,3,4 Shikurobutanteto
Lacarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dianhydride
Thing, 1,3,3a, 4,5,9b- hexahydro-5- (te
Trahydro-2,5-dioxo-3-furanyl) -naph
[1,2-c] furan-1,3-dione, 1,3,3a, 4,5,9b-hexahydro-8-methyl
Ru-5- (tetrahydro-2,5-dioxo-3-fura
Nyl) -naphtho [1,2-c] furan-1,3-dio
, Pyromellitic dianhydride, and represented by the following formula (a)
Compound. Embedded image 4. It contains two kinds of polymers having different imidation ratios.
The polymer having a low imidation ratio is 2,3,5-tricarbohydrate.
Xycyclopentylacetic acid dianhydride, 1,3,3a, 4
5,9b-Hexahydro-8-methyl-5- (tetrahi
Dro-2,5-dioxo-3-furanyl) -naphtho
[1,2-c] furan-1,3-dione, pyromerit
Acid dianhydride and 1,3-dimethyl-1,2,3,4-
Te selected from cyclobutanetetracarboxylic dianhydride
Reaction of tracarboxylic dianhydride with diamine compound
Claim 1 characterized by being obtained by
4. The liquid crystal aligning agent according to claim 3. 5. The method according to claim 1, wherein
Characterized by having a liquid crystal alignment film obtained from a liquid crystal alignment agent
Liquid crystal display element.