JPH0971650A - Polyamic acid, polyimide and liquid crystal orienting agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new polyamic acid useful as a liquid crystal orienting agent capable of manifesting good orienting characteristics and providing a liquid crystal oriented film having a short afterimage erasing time by reacting a specific tetracarboxylic dianhydride with a specified diamine compound. SOLUTION: This polyamic acid is obtained by reacting (A) a tetracarboxylic dianhydride containing a compound of the formula [R<1> is a bivalent organic group; R<2> and R<3> are each a monovalent organic group; R<4> and R<5> are each H or methyl; (a) and (b) are each 0-4] with a diamine compound of the formula H2 N-R<6> -NH2 (R<6> is a bivalent organic group) (e.g. 4,4'-diaminodiphenylmethane). Furthermore, the ratio of the components (A) to (B) used is regulated so as to provide 0.3-1.2 equiv. acid anhydride groups of the component (A) based on 1 equiv. amino groups contained in the component (B) and both the components are preferably reacted under temperature conditions of 0-100 deg.C in an organic solvent such as N,N-dimethylacetamide.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel polyamic acid and a novel polyimide, and a liquid crystal aligning agent containing at least one of them.

[0002]

2. Description of the Related Art At present, as a liquid crystal display device, a liquid crystal alignment film made of polyimide or the like is formed on the surface of a substrate on which a transparent conductive film is provided to form a substrate for the liquid crystal display device.
The two sheets are arranged opposite to each other and a nematic liquid crystal layer having a positive dielectric anisotropy is formed in the gap to form a cell having a sandwich structure. The major axis of the liquid crystal molecules is transferred from one substrate to the other substrate. It was made to twist continuously 90 degrees toward
2. Description of the Related Art A TN type liquid crystal display device having a so-called TN (Twisted Nematic) liquid crystal cell is known. In addition, recently, STN (S has a higher contrast than a TN type liquid crystal display element and has less viewing angle dependence.
An upper Twisted Nematic type liquid crystal display device has been developed. This STN type liquid crystal display element uses a nematic type liquid crystal blended with a chiral agent as an optically active substance as a liquid crystal, and the major axis of the liquid crystal molecule is continuously twisted over 180 degrees between substrates. This makes use of the birefringence effect generated by this. The alignment of the liquid crystal in the TN type liquid crystal display element and the STN type liquid crystal display element is usually expressed by a rubbed liquid crystal alignment film.

[0003]

However, in the conventional liquid crystal display element, since the ionic charge generated when a voltage is applied is adsorbed to the liquid crystal alignment film, the voltage after the application of the voltage is released. There is a problem that a sufficient contrast cannot be obtained because an afterimage is generated on the display screen and the difference in brightness of the liquid crystal display element between when the voltage is applied and when it is released is small.
The present invention has been made to solve such a problem.

A first object of the present invention is to provide a novel polyamic acid useful as a liquid crystal aligning agent. A second object of the present invention is to provide a novel polyimide useful as a liquid crystal aligning agent. A third object of the present invention is that, in addition to being able to exhibit good alignment characteristics, the time from the application of a voltage to the liquid crystal display element until the afterimage is erased (hereinafter referred to as “afterimage erasing time”). It is to provide a liquid crystal aligning agent capable of forming a liquid crystal aligning film having a short (.

[0005]

The polyamic acid of the present invention comprises a tetracarboxylic dianhydride containing a compound represented by the following general formula (I) and a diamine compound represented by the following general formula (II). It is characterized by being obtained by reacting with.

[0006]

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The polyimide of the present invention has the following general formula:
It has a repeating unit represented by (III).

[0008]

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The liquid crystal aligning agent of the present invention is characterized by containing the above polyamic acid and / or the above polyimide.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. <Tetracarboxylic acid dianhydride> The polyamic acid of the present invention is a compound represented by the above general formula (I) (hereinafter,
It is called "specific tetracarboxylic dianhydride". ) Is used.

In the general formula (I) representing the specific tetracarboxylic dianhydride, the divalent organic group represented by R ¹ is a phenylene group, or the following general formulas (IV) to (VI) There may be mentioned valent organic groups.

[0012]

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The monovalent organic groups represented by R ² and R ³ include alkyl groups such as methyl group, ethyl group and butyl group; aryl groups such as phenyl group and naphthyl group;
An acetyl group etc. can be mentioned.

The specific tetracarboxylic dianhydride comprises a bismaleimide compound and a styrene compound in a Diels-
It can be synthesized by an Alder reaction and ene reaction of the reaction product with maleic anhydride.

The bismaleimide compound used in the Diels-Alder reaction is N, N'-1,3.
-Phenylene dimaleimide, N, N'-1,4-phenylene dimaleimide, 3,3'-bismaleimide diphenylmethane, 3,4'-bismaleimide diphenylmethane, 4,4'-bismaleimide diphenylmethane and the like can be mentioned. . Among these, N, N'-1,4-phenylene dimaleimide and 4,4'-bismaleimide diphenylmethane are preferable from the viewpoint of the coating film strength of the polymer to be synthesized.

Examples of styrene compounds used in the Diels-Alder reaction include styrene, 4-methylstyrene, 4-t-butylstyrene, 4-hydroxystyrene, 4-phenylstyrene, 4-acetylstyrene,
4-fluorostyrene, 4-nitrostyrene, 4-naphthylstyrene, α-methylstyrene, 4-methyl-α-methylstyrene, 3,4-dimethyl-α-methylstyrene, 4-t-butyl-α-methyl Examples thereof include styrene, 4-phenyl-α-methylstyrene, 4-acetyl-α-methylstyrene, and 4-naphthyl-α-methylstyrene. Among these, styrene is used from the viewpoint of reactivity with the bismaleimide compound. Is preferred.

Specific examples of the specific tetracarboxylic dianhydride include compounds represented by the following chemical formulas (1) and (2). For example, the compound represented by the chemical formula (1) is as follows: According to reaction formula A, N, N′-1,4-phenylenedimaleimide and styrene are subjected to a Diels-Alder reaction, and the reaction product is subjected to an ene reaction with maleic anhydride.

[0018]

[Chemical 6]

[0019]

[Chemical 7]

As the tetracarboxylic acid dianhydride used in the synthesis reaction of the polyamic acid, compounds other than the specific tetracarboxylic acid dianhydride can be used in combination within the range where the effect of the present invention is not impaired. is there. Here, the ratio of the specific tetracarboxylic dianhydride to the tetracarboxylic dianhydride used in the synthesis reaction is 0.1 to 1
The amount is set to 00 mol%, preferably 50 to 100 mol%.

Examples of the tetracarboxylic dianhydride which can be used in combination include butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4- Cyclopentane tetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofuran tetra Carboxylic dianhydride, 5- (2,5-
Dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid dianhydride, bicyclo [2,2,2] -oct-7-ene-2,3,5,6-
Aliphatic tetracarboxylic dianhydrides such as tetracarboxylic dianhydride; pyromellitic dianhydride, 3,3 ', 4
4'-benzophenone tetracarboxylic 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'-diphenylether dianhydride, bis (tri Phenylphthalic acid) -4,4'-diphenylmethane dianhydride, 1,3,3a, 4,5,9b-hexahydro-5- (tetrahydro-2,5-dioxo-
3-furanyl) -naphtho [1,2-c] -furan-1,
Aromatic tetracarboxylic dianhydrides such as 3-dione can be mentioned, and these can be used alone or in combination of two or more kinds.

Of these, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride and 2,3,5-tricarboxycyclopentyl acetic acid. Dianhydride, 1,3,3
a, 4,5,9b-Hexahydro-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 acid dianhydride and the like are preferable, and 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride and 2,3,5-tricarboxycyclopentylacetic acid dianhydride are particularly preferable.

<Diamine compound> The polyamic acid of the present invention
Represented by the above general formula (II), which is used in the acid synthesis reaction
As the diamine compound, p-phenylenediamine, m
-Phenylenediamine, 4,4'-diaminodiphenyl
Methane, 4,4'-diaminodiphenylethane, 4,
4'-diaminodiphenyl sulfide, 4,4'-dia
Minodiphenyl sulfone, 3,3'-dimethyl-4,
4'-diaminobiphenyl, 4,4'-diaminobenz
Anilide, 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'-diaminodipheny
Ether, 3,3'-diaminobenzophenone, 3,
4'-diaminobenzophenone, 4,4'-diaminophen
Nzophenone, 2,2-bis [4- (4-aminopheno
Xy) phenyl] propane, 2,2-bis [4- (4-
Aminophenoxy) phenyl] hexafluoropropa
2,2-bis (4-aminophenyl) hexafluor
L-propane, 2,2-bis [4- (4-aminophenoxy
Si) phenyl] sulfone, 1,4-bis (4-aminoph
Enoxy) benzene, 1,3-bis (4-aminopheno)
Xy) benzene, 1,3-bis (3-aminophenoxy)
Si) benzene, 9,9-bis (4-aminophenyl)-
10-hydroanthracene, 2,7-diaminofluore
1,9,9-bis (4-aminophenyl) fluorene,
4,4'-methylene-bis (2-chloroaniline),
2,2 ', 5,5'-tetrachloro-4,4'-diami
Noviphenyl, 2,2'-dichloro-4,4'-diami
No-5,5'-dimethoxybiphenyl, 3,3'-dime
Toxy-4,4'-diaminobiphenyl, 1,4.4 '
-(P-phenylene isopropylidene) bisaniline,
4,4 '-(m-phenylene isopropylidene) bisua
Niline, 2,2'-bis [4- (4-amino-2-tri
Fluoromethylphenoxy) phenyl] hexafluoro
Propane, 4,4'-diamino-2,2'-bis (tri
Fluoromethyl) biphenyl, 4,4'-bis [(4-
Amino-2-trifluoromethyl) phenoxy] -octyl
Aromatic diamines such as tafluorobiphenyl; diamino
Aromatic compounds containing heteroatoms such as tetraphenylthiophene
Aromatic diamine; 1,1-meta-xylylenediamine, 1,
3-propanediamine, tetramethylenediamine, pen
Tamethylenediamine, hexamethylenediamine, hepta
Methylenediamine, octamethylenediamine, nonamechi
Diamine, 4,4-diaminoheptamethylenediami
1,4-diaminocyclohexane, isophoronedia
Min, tetrahydrodicyclopentadiene diamine
Hexahydro-4,7-methanoindanylene dimethy
Diamine, tricyclo [6,2,1,0 ^2.7] -U
Ndecylenedimethyldiamine, 4,4'-methylenebis
Aliphatic diamines such as (cyclohexylamine) and
Alicyclic diamine; represented by the following chemical formulas (3) to (5)
There may be mentioned compounds, which may be used alone or in two kinds.
The above can be used in combination.

[0024]

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Of these, p-phenylenediamine,
4,4'-diaminodiphenylmethane, 1,5-diaminonaphthalene, 2,7-diaminofluorene, 4,4 '
-Diaminodiphenyl ether, 4.4 '-(p-phenylene isopropylidene) bisaniline, 2,2-bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexa Fluoropropane, 2,2'-bis [4- (4-amino-2-trifluoromethylphenoxy) phenyl]
Hexafluoropropane, 4,4'-diamino-2,
2'-bis (trifluoromethyl) biphenyl, 4,
4'-bis [(4-amino-2-trifluoromethyl)
Phenoxy] -octafluorobiphenyl and the like are preferable, and p-phenylenediamine, 4,
4'-diaminodiphenylmethane and 4,4 '-(p
-Phenylene isopropylidene) bisaniline.

<Polyamic Acid> The polyamic acid of the present invention comprises a tetracarboxylic dianhydride containing a compound represented by the general formula (I) and a diamine compound represented by the general formula (II). It is synthesized by ring-opening polyaddition.

The ratio of tetracarboxylic dianhydride and diamine compound used in the polyamic acid synthesis reaction is
The ratio in which the acid anhydride group of the tetracarboxylic dianhydride is 0.2 to 2 equivalents is preferable with respect to 1 equivalent of the amino group contained in the diamine compound, and more preferably 0.3 to 1.
It is a ratio of 2 equivalents.

The synthesis reaction of polyamic acid is usually 0 to 150 ° C., preferably 0 to 100 ° C. in an organic solvent.
It is performed under the temperature conditions of. Here, as the organic solvent,
There is no particular limitation as long as it can dissolve the synthesized polyamic acid, for example, N-methyl-2-pyrrolidone,
Aprotic polar solvent such as N, N-dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide; m-cresol, xylenol, phenol, halogenated phenol, etc. The phenolic solvent can be exemplified. The amount (a) of the organic solvent used is usually such that the total amount (b) of the tetracarboxylic dianhydride and the diamine compound is 0.1 to 30% by weight based on the total amount (a + b) of the reaction solution. It is preferable that the amount is large.

The organic solvent includes 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, ethylene glycol monomethyl ether, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, butyl acetate, diethyl oxalate, diethyl malonate, diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene Glycol-n-propyl ether, ethylene glycol-i-propyl ether, ethylene glycol-n-
Butyl ether, ethylene glycol dimethyl ether, ethylene glycol ethyl ether acetate, 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, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1 , 4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene and the like can be mentioned.

The reaction solution obtained by dissolving the polyamic acid of the present invention is obtained as described above. 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. The polyamic acid can be purified by dissolving the polyamic acid in an organic solvent again and then performing a step of precipitating with a poor solvent once or several times.

The polyamic acid obtained as described above has a logarithmic viscosity (ηln) value of usually from 0.05 to 10
dl / g, preferably 0.05 to 5 dl / g. The value of logarithmic viscosity (ηln) in the present invention is N-methyl-
Using 2-pyrrolidone as a solvent, the concentration is 0.5 g / 1
The viscosity is measured at 30 ° C. with respect to a solution having a volume of 00 ml, and is obtained by the following mathematical formula.

[0032]

[Equation 1]

<Polyimide> The polyimide of the present invention is
(I) dehydration ring closure (imidization) by heating the polyamic acid or by dissolving the polyamic acid in an organic solvent and adding a dehydrating agent and an imidization catalyst to the solution and heating if necessary. Or (ii) the above-mentioned specific tetracarboxylic acid dianhydride and a diisocyanate compound are mixed and heated as necessary to cause condensation to be synthesized.

In the reaction (i), the reaction temperature in the method of heating the polyamic acid is usually 60 to
The temperature is set to 250 ° C, preferably 100 to 170 ° C. If the reaction temperature is lower than 60 ° C, the imidization reaction may not proceed sufficiently, and if the reaction temperature exceeds 250 ° C, the molecular weight of the polyimide obtained may decrease.

On the other hand, in the above reaction (i), the dehydrating agent in the method of adding the dehydrating agent and the imidization catalyst to the solution of polyamic acid may be, for example, acetic anhydride, propionic anhydride, trifluoroacetic anhydride or the like. Anhydrides can be used. The amount of the dehydrating agent used is preferably 1.6 to 20 mol per 1 mol of the repeating unit of the polyamic acid. Further, as the imidation catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, and triethylamine can be used, but are not limited thereto. The amount of imidization catalyst used is
The amount is preferably 0.5 to 10 mol with respect to 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 the polyamic acid can be exemplified. The reaction temperature for dehydration ring closure is usually 0 to 180 ° C, preferably 60 to 150 ° C. Further, the polyimide of the present invention can be purified by performing the same operation on the reaction solution thus obtained as in the method for purifying a polyamic acid.

Specific examples of the diisocyanate compound used in the reaction (ii) above include aliphatic diisocyanate compounds such as hexamethylene diisocyanate; cycloaliphatic diisocyanate compounds such as cyclohexane diisocyanate; diphenylmethane-4,4 '.
-Diisocyanate, diphenyl ether-4,4'-
Diisocyanate, diphenylsulfone-4,4'-diisocyanate, diphenylsulfide-4,4'-diisocyanate, 1,2-diphenylethane-p, p '
-Diisocyanate, 2,2-diphenylpropane-
p, p'-diisocyanate, 2,2-diphenyl-
1,1,1,3,3,3-hexafluoropropane-
p, p'-diisocyanate, 2,2-diphenylbutane-p, p'-diisocyanate, diphenyldichloromethane-4,4'-diisocyanate, diphenylfluoromethane-4,4'-diisocyanate, benzophenone-4,4 'diisocyanate, Aromatic diisocyanate compounds such as N-phenylbenzoic acid amide-4,4′-diisocyanate can be mentioned, and these can be used alone or in combination of two or more.
A catalyst is not particularly required for the above reaction (ii),
The reaction temperature is usually 50 to 200 ° C, preferably 100 to 200 ° C.
160 ° C.

The polyimide obtained by the above reactions (i) and (ii) has a logarithmic viscosity (ηln) of usually 0.05 to 10 dl / g, preferably 0.05 to 5 d.
1 / g.

<Liquid Crystal Aligning Agent> The liquid crystal aligning agent of the present invention comprises the polyamic acid and / or polyimide of the present invention dissolved and contained in an organic solvent. Examples of the organic solvent that constitutes the liquid crystal aligning agent include the solvents exemplified as those used for the synthetic reaction of polyamic acid. 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 concentration of polyamic acid and / or polyimide in the liquid crystal aligning agent of the present invention is selected in consideration of viscosity, volatility, etc., but preferably 1 to 10% by weight.
Range. That is, the liquid crystal aligning agent of the present invention is applied to the surface of a substrate to form a coating film to be a liquid crystal alignment film, but when the concentration is less than 1% by weight, the film thickness of this coating film is too small. When the concentration exceeds 10% by weight, the film thickness of the coating film becomes too large to obtain a good liquid crystal alignment film. The viscosity of the aligning agent increases and the coating characteristics deteriorate.

The polyamic acid and polyimide used in the liquid crystal aligning agent of the present invention may be of a terminal-modified type in which the molecular weight is adjusted. By using this end-modified polyamic acid and polyimide, the application characteristics of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. Such end-modified types are
When synthesizing polyamic acid or polyimide, acid-
It can be synthesized by adding an anhydride or a monoamine compound to the reaction system.

Here, examples of the acid-anhydride include maleic anhydride, phthalic anhydride, and nadic acid anhydride, and examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine, and n. -Pentylamine, n-hexylamine, n-heptylamine, n-octylamine, n-nonylamine, n-decylamine, n-undecylamine, n-dodecylamine, n-tridecylamine, n-tetradecylamine, Examples thereof include n-pentadecylamine, n-hexadecylamine, n-heptadecylamine, n-octadecylamine and n-eicosylamine.

The liquid crystal aligning agent of the present invention may contain a functional silane-containing compound from the viewpoint of improving the adhesion of polyamic acid and / or polyimide to the substrate surface. Examples of such functional silane-containing compounds include 3-aminopropyltrimethoxysilane and 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-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
-Aminopropyltriethoxysilane, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, N-bis (oxyethylene) -3-aminopropyltriethoxysilane and the like can be mentioned.

<Liquid Crystal Display Device> A liquid crystal display device obtained by using the liquid crystal aligning agent of 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 one surface of a substrate provided with a patterned transparent conductive film by, for example, a roll coater method, a spinner method, a printing method or the like, and then the applied surface. A coating film is formed by heating. Here, as the substrate, for example, a transparent substrate made of glass such as float glass or soda glass; or a plastic such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone, or polycarbonate can be used. As the transparent conductive film provided on one surface of the substrate, a NESA film made of tin oxide (SnO ₂ ) (registered trademark of PPG Co. in the United States) and I made of indium oxide-tin oxide (In ₂ O ₃ —SnO ₂ ).
A TO film or the like can be used, and a photo-etching method or a method using a mask in advance is used for patterning these transparent conductive films. In applying the liquid crystal aligning agent, a functional silane-containing compound, a functional titanium-containing compound, etc. are applied in advance to the substrate surface and the surface of the substrate in order to further improve the adhesion between the transparent conductive film and the coating film. You can also. The heating temperature after applying the liquid crystal aligning agent is 80 to 2
The temperature is set to 50 ° C., preferably 120 to 200 ° C.
The liquid crystal aligning agent of the present invention containing a polyamic acid forms a coating film to be an alignment film by removing the organic solvent after coating, but further heated to promote dehydration ring closure and imidization. It can also be a coating film. The thickness of the formed coating film is usually 0.001 to 1 μm.
m, and preferably 0.005 to 0.5 μm.

(2) A rubbing treatment is performed in which the formed coating film surface is rubbed in a certain direction with a roll around which a cloth made of fibers such as nylon, rayon, and cotton is wound. Thereby, the alignment ability of the liquid crystal molecules is imparted to the coating film to form a liquid crystal alignment film.

Further, the liquid crystal alignment film formed by the liquid crystal aligning agent of the present invention is partially irradiated with ultraviolet rays as disclosed in, for example, JP-A-6-222366 and JP-A-6-281937. Processing for changing the pretilt angle by
As shown in Japanese Patent No. 544, a resist film is partially formed on the surface of a liquid crystal alignment film that has been subjected to a rubbing treatment, and the rubbing treatment is performed in a direction different from the previous rubbing treatment, and then the resist film is removed. By performing a treatment that changes the liquid crystal alignment ability of the liquid crystal alignment film, it is possible to improve the visibility characteristics of the liquid crystal display element.

(3) Two substrates on which the liquid crystal alignment film is 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. Facing each other through (cell gap),
The peripheral portions of the two substrates are bonded together using a sealant, and liquid crystal is injected and filled into the cell gap defined by the substrate surface and the sealant, and the injection holes are 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.

Here, as the sealant, for example, a curing agent and an epoxy resin containing aluminum oxide spheres as spacers can be used. Examples of the liquid crystal include a nematic liquid crystal and a smectic liquid crystal. Among them, a nematic liquid crystal is preferable. For example, a Schiff base liquid crystal, an azoxy liquid crystal,
Biphenyl-based liquid crystal, phenylcyclohexane-based liquid crystal, ester-based liquid crystal, terphenyl-based liquid crystal, biphenylcyclohexane-based liquid crystal, pyrimidine-based liquid crystal, dioxane-based liquid crystal, bicyclooctane-based liquid crystal, cubane-based liquid crystal, and the like can be 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 it. Further, p-decyloxybenzylidene-p
Ferroelectric liquid crystals such as -amino-2-methylbutyl cinnamate can also be used. Further, as a polarizing plate to be bonded to the outer surface of the liquid crystal cell, a polarizing plate or an H film in which a polarizing film called an H film absorbing iodine is sandwiched by a cellulose acetate protective film while stretching and aligning polyvinyl alcohol. A polarizing plate composed of itself can be mentioned.

[0049]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the following examples and comparative examples, the evaluation methods for the afterimage erasing time and the liquid crystal orientation in the liquid crystal display element are as follows.

[Afterimage erasing time] After a direct current voltage of 10 V is applied to the liquid crystal display element for 1 hour, the application of the voltage is released, the display screen is visually observed, and after the application of the voltage is released, on the screen. The time until the afterimage of is erased was measured.

[Alignment of Liquid Crystal] The presence or absence of an abnormal domain when a voltage was turned on / off (applied / released) to the liquid crystal display element was observed with a polarizing microscope, and when there was no abnormal domain, it was determined as “good”.

(Synthesis Example 1) 77.29 g of the specific tetracarboxylic acid dianhydride represented by the above chemical formula (1) (114.
5 mmol) and 4,4'-diaminodiphenylmethane 2
2.71 g (114.5 mmol) and N-methyl-
It was dissolved in 900 g of 2-pyrrolidone and reacted at 60 ° C. for 6 hours. Then, the reaction solution was poured into a large excess of methyl alcohol to precipitate a reaction product. Then, it is washed with methyl alcohol and dried under reduced pressure at 40 ° C. for 15 hours to obtain a polyamic acid of the present invention having an inherent viscosity of 0.96 dl / g [this will be referred to as “polyamic acid (a)”]. ] 89.85 g was obtained.

Synthesis Example 2 50.00 g of the polyamic acid (a) obtained in Synthesis Example 1 was dissolved in 950 g of N-methyl-2-pyrrolidone, and 9.06 g of pyridine was added to this solution.
And 11.70 g of acetic anhydride were added, and the mixture was dehydrated and ring-closed by heating at 115 ° C. for 4 hours. Then, the reaction product solution is precipitated and dried in the same manner as in Synthesis Example 1 to obtain the polyimide of the present invention having an inherent viscosity of 0.96 dl / g [this is referred to as "polyimide (a)"]. ] 39.05g was obtained.

(Synthesis Example 3) The amount of the specific tetracarboxylic dianhydride used was changed to 86.18 g (127.7 mmol), and p was replaced with 4,4'-diaminodiphenylmethane.
-A polyamic acid of the present invention having a logarithmic viscosity of 1.08 dl / g in the same manner as in Synthesis Example 1 except that 13.81 g (127.7 mmol) of phenylenediamine was used [this is referred to as "polyamic acid (b)"]. ". ] 92.3
0 g was obtained.

(Synthesis Example 4) 76.24 g of the specific tetracarboxylic acid dianhydride represented by the above chemical formula (1) (113.
0 mmol) and 1.17 g (6.0 mmol) of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride and p-
5.79 g (53.5 mmol) of phenylenediamine and 10.61 g (5 of 4,4'-diaminodiphenylmethane)
(3.5 mmol) and 6.19 g (11.9 mmol) of the diamine compound represented by the above chemical formula (3) were dissolved in 900 g of N-methyl-2-pyrrolidone and the mixture was mixed at 60 ° C. for 6 hours.
The polyamic acid of the present invention having a logarithmic viscosity of 0.88 dl / g was obtained in the same manner as in Synthesis Example 1 except that the reaction was carried out for a time. This is referred to as "polyamic acid (c)". ] 88.4
1 g was obtained. Then, the polyimide of the present invention having a logarithmic viscosity of 0.88 dl / g is prepared in the same manner as in Synthesis Example 2 except that the polyamic acid (c) is used in place of the polyamic acid (a). ) ”. ] 3
Obtained 8.27 g.

COMPARATIVE SYNTHESIS EXAMPLE 1 Instead of the specific tetracarboxylic acid dianhydride, 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride 49.73 g (253.6 mmol)
Was used and the amount of 4,4′-diaminodiphenylmethane used was changed to 50.27 g (253.6 mmol), and the logarithmic viscosity was 1.20 d.
A polyamic acid for comparison having a ratio of 1 / g [this is referred to as "polyamic acid (x)". ] 83.44g was obtained. Then, in the same manner as in Synthesis Example 2 except that the polyamic acid (x) was used in place of the polyamic acid (a), a comparative polyimide having a logarithmic viscosity of 1.20 dl / g [this was referred to as "polyimide (x ) ”. ] 40.02g
I got

COMPARATIVE SYNTHESIS EXAMPLE 2 Instead of the specific tetracarboxylic acid dianhydride, 64.46 g (328.7 mmol) of 1,2,3,4-cyclobutanetetracarboxylic acid dianhydride was used.
Was used in the same manner as in Synthesis Example 1 except that 35.54 g (328.7 mmol) of p-phenylenediamine was used in place of 4,4′-diaminodiphenylmethane.
A polyamic acid for comparison having a logarithmic viscosity of 1.26 dl / g [this is referred to as "polyamic acid (y)". ] 8
3.25 g was obtained.

(Comparative Synthesis Example 3) 1,3,3 instead of the specific tetracarboxylic dianhydride represented by the above chemical formula (1)
a, 4,5,9b-Hexahydro-5- (tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2
-C] -furan-1,3-dione 34.36 g (11
Comparative Polyamic acid having a logarithmic viscosity of 1.00 dl / g in the same manner as in Synthesis Example 1 except that 4.5 mmol) was used [this is referred to as "polyamic acid (z)". ] 46.95g was obtained. Then, in the same manner as in Synthesis Example 2 except that 40.00 g of the polyamic acid (z) was used instead of the polyamic acid (a), a comparative polyimide having a logarithmic viscosity of 1.00 dl / g [ Polyimide (z) ”. ] 30.64 g was obtained.

Example 1 (1) Preparation of Liquid Crystal Alignment Agent: The polyimide (a) obtained in Synthesis Example 2 was dissolved in γ-butyrolactone to obtain a solution having a solid content concentration of 4% by weight, and this solution had a pore size of The liquid crystal aligning agent of the present invention was prepared by filtering with a 1 μm filter.

(2) Fabrication of liquid crystal display element: ITO provided on one surface of a glass substrate having a thickness of 1 mm
On a transparent conductive film made of a film, the liquid crystal alignment agent of the present invention prepared as described above is applied using a spinner,
By drying at 80 ° C. for 1 hour, a coating film having a dry film thickness of 800 ° was formed.

The formed coating film surface was subjected to rubbing treatment using a rubbing machine having a roll around which a cloth made of nylon was wound to prepare a liquid crystal alignment film. Here, the rubbing treatment condition is the rotation speed of the roll of 50.
The speed was 0 rpm and the moving speed of the stage was 1 cm / sec.

Two substrates on which the liquid crystal alignment film was formed as described above were prepared, and an epoxy resin adhesive containing aluminum oxide spheres having a diameter of 17 μm was applied to the outer edge of each substrate by screen printing. After that, the two substrates were arranged so as to face each other with a gap so that the rubbing directions of the respective liquid crystal alignment films were antiparallel, and the outer edge portions were brought into contact with each other and pressure-bonded to cure the adhesive.

Nematic liquid crystal “MLC-2001” (manufactured by Merck Ltd.) was injected and filled into the cell gap defined by the adhesive on the surface and the outer edge of the substrate, and then the injection hole was sealed with an epoxy adhesive. Then, the liquid crystal cell was constructed. Thereafter, a polarizing plate was attached to the outer surface of the liquid crystal cell such 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 element.

In the liquid crystal display element manufactured as described above, no abnormal domain was observed when a voltage was applied and released, and the liquid crystal alignment was good. Further, the afterimage erasing time of the liquid crystal display element was 0.20 seconds, which was extremely short.

Example 2 Instead of the polyimide (a),
A liquid crystal aligning agent was prepared and a liquid crystal display device was produced in the same manner as in Example 1 except that the polyamic acid (b) obtained in Synthesis Example 3 was used. The produced liquid crystal display element had no abnormal domain when a voltage was applied and released, and the liquid crystal orientation was good. In addition, the afterimage erasing time of the liquid crystal display element was 0.14 seconds, which was extremely short.

Example 3 A liquid crystal aligning agent was prepared and a liquid crystal display device was prepared in the same manner as in Example 2 except that the drying temperature after coating the liquid crystal aligning agent was 250 ° C. By setting the drying temperature to 250 ° C., the imidization of the coating film proceeded simultaneously with the removal of the solvent, and the liquid crystal alignment film mainly containing polyimide was formed. The produced liquid crystal display element has no abnormal domain when a voltage is applied or released,
The alignment of the liquid crystal was good. The afterimage erasing time of the liquid crystal display element was 0.25 seconds, which was extremely short.

Example 4 Instead of the polyimide (a),
A liquid crystal aligning agent was prepared and a liquid crystal display device was produced in the same manner as in Example 1 except that the polyimide (b) obtained in Synthesis Example 4 was used. The produced liquid crystal display element had no abnormal domain when a voltage was applied and released, and the liquid crystal orientation was good. Further, the afterimage erasing time of the liquid crystal display element was 0.10 seconds, which was extremely short.

[Comparative Example 1] Instead of the polyimide (a),
A liquid crystal aligning agent was prepared and a liquid crystal display element was produced in the same manner as in Example 1 except that the polyimide (x) obtained in Comparative Synthesis Example 1 was used. The produced liquid crystal display device showed no abnormal domains when a voltage was applied and released, and the liquid crystal alignment was good, but the afterimage erasing time of the liquid crystal display device was 12 seconds, and the afterimage disappeared. It took a long time to be played.

[Comparative Example 2] Instead of the polyimide (a),
A liquid crystal aligning agent was prepared and a liquid crystal display device was produced in the same manner as in Example 1 except that the polyamic acid (y) obtained in Comparative Synthesis Example 2 was used. The produced liquid crystal display element showed no abnormal domains when a voltage was applied and released, and the liquid crystal orientation was good, but the afterimage erasing time of the liquid crystal display element was 10 seconds, and the afterimage disappeared. It took a long time to be played.

[Comparative Example 3] Instead of the polyimide (a),
A liquid crystal aligning agent was prepared and a liquid crystal display device was prepared in the same manner as in Example 1 except that the polyimide (z) obtained in Comparative Synthesis Example 3 was used. The produced liquid crystal display element showed no abnormal domains when a voltage was applied and released, and the liquid crystal alignment was good, but the afterimage erasing time of the liquid crystal display element was 6 seconds, and the afterimage disappeared. It took a long time to be played.

[0071]

According to the invention described in claim 1, a novel polyamic acid useful as a liquid crystal aligning agent can be provided.

According to the invention described in claim 2, a novel polyimide useful as a liquid crystal aligning agent can be provided.

According to the third aspect of the present invention, it is possible to provide a liquid crystal aligning agent which has good alignment characteristics and can form a liquid crystal aligning film having a short afterimage erasing time in a liquid crystal display device.

The liquid crystal alignment film formed by the liquid crystal aligning agent of the present invention is applicable not only to TN type liquid crystal display elements and STN type liquid crystal display elements but also to SH (Super Homeotrope).
ic) type liquid crystal display elements and can be suitably used for forming various liquid crystal display elements. In addition, a liquid crystal display device including the liquid crystal alignment film has excellent liquid crystal alignment and reliability, and can be effectively used for various devices. For example, a desk calculator, a wristwatch, a clock, a counting display,
It can be suitably used as a display device such as a word processor, a personal computer, and a liquid crystal television.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Akio Hiraharu 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (3)

[Claims] 1. A tetracarboxylic acid dianhydride containing a compound represented by the following general formula (I) and the following general formula (II):
A polyamic acid obtained by reacting with a diamine compound represented by. Embedded image 2. A polyimide having a repeating unit represented by the following general formula (III). Embedded image 3. The polyamic acid according to claim 1, and / or
Alternatively, a liquid crystal aligning agent containing the polyimide according to claim 2.