JPH09208695A - Alignment film, optically anisotropic substance, and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prepare an alignment film for optically anisotropic substances by using a polyimide obtained by reacting a diamino compound represented by a specified formula with a tetracarboxylic acid dianhydride as the principal component. SOLUTION: A tetracarboxylic acid dianhydride (e.g. pyromellitic dianhydride) represented by formula II (wherein Y is a 2C or higher tetravalent organic group) is added to a solution prepared by dissolving a diamino compound (e.g. 1.1-bis([4-(4-aminophenoxy)-3-t-butyl-6-methylphenyl]butane) represented by formula I (wherein X is a 1-20C hydrocarbon group or the like; and (a) is 0-4) in N-methyl-2-pyrrolidone and reacted at room temperature to obtain a polyamic acid solution. A solution prepared by heating the polyamic acid solution to imidize the polyamic acid is added dropwise to methanol under agitation to deposit a polyimide powder. A solution prepared by dissolving this powder in, e.g. toluene is applied to a polymer film to obtain an alignment film having a film thickness of about 0.1-100μm and used for optically anisotropic substances.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an alignment film for an optically anisotropic substance, an optically anisotropic substance, a liquid crystal cell using the optically anisotropic substance, and a liquid crystal display device.

[0002]

2. Description of the Related Art As a method for favorably orienting an optically anisotropic substance on a substrate, there is a technique of forming an orientation film on the substrate and orienting the optically anisotropic substance thereon. Examples of the type of alignment film include polyimide and polyvinyl alcohol. However, polyvinyl alcohol has a problem that it has a high hygroscopic property, the substrates stick to each other during storage, and the heat resistance is poor. In addition, the conventional polyimide alignment film has excellent physical properties such as high heat resistance, high adhesion, good insulation, low moisture absorption, and low dielectric constant. However, since polyimide is generally insoluble in a solvent, in order to form an alignment film, after coating a substrate with a polyamic acid precursor,
It is necessary to dry and imidize. However, since polyamic acid is easily hydrolyzed and lacks long-term storage stability, it is necessary to treat the polyamic acid at a high temperature of 200 ° C. or higher for several hours at the time of imidization, so that an inexpensive general-purpose polymer film cannot be used. However, there is a problem that the coated substrate is limited to glass or engineering plastic, which has poor handleability. Further, in order to solve the above problem, a solvent-soluble polyimide has been developed, but the soluble solvent is limited, and it cannot be used for an inexpensive polymer film.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an alignment film which can be formed by a low temperature process that can withstand a general-purpose polymer while maintaining the excellent physical properties peculiar to polyimide, particularly polycarbonate, cellulose triacetate or An object of the present invention is to provide an alignment film that can be formed below the glass transition temperature of a polymer such as polyether sulfone. It is another object of the present invention to provide an optically anisotropic substance, a liquid crystal cell using the same, and a liquid crystal display device by using the alignment film at a low cost and without a complicated process.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the inventors have found that a polyimide having a specific structure is soluble in an organic solvent without impairing the physical properties peculiar to the polyimide. It has been found that it has excellent moldability and can be a good alignment film of an optically anisotropic substance. further,
The present invention was found to show that when an optically anisotropic substance obtained by orienting an optically anisotropic substance using this orientation film is used in a liquid crystal display device as an optical compensation film, good viewing angle characteristics are exhibited. Has been completed. That is, the present invention
It consists of the following inventions. [1] General formula (1)

Embedded image (In the formula, X represents a hydrocarbon group having 1 to 20 carbon atoms or a sulfur atom. R represents a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms or a halogen-containing hydrocarbon group having 1 to 6 carbon atoms,
a is an integer of 0 to 4 and represents the number of substituents. However, multiple R
And a may independently have different substituents and values. ) And a diamino compound represented by the general formula (2)

[Chemical 6] (In the formula, Y represents a tetravalent organic group having 2 or more carbon atoms.) A main component is a polyimide obtained by reacting a tetracarboxylic dianhydride represented by Alignment film for isotropic substances. [2] The diamino compound of the general formula (1) has the formula (a)

Embedded image (In the formula, X represents a butylidene group or a sulfur atom.) The alignment film for an optically anisotropic substance according to [1]. [3] In the general formula (1), X is the formula (b), (c) or (d).

Embedded image An alignment film for an optically anisotropic substance according to [1], which is represented by: [4] An alignment film for an optically anisotropic substance, characterized in that the alignment film described in [1], [2] or [3] is formed on a polymer film. [5] Alignment for an optically anisotropic substance, characterized in that the alignment film described in [1], [2], [3] or [4] is formed on a conductor or a semiconductor. film. [6] The alignment film described in [1], [2], [3], [4] or [5] is applied on a substrate on which an inorganic transparent substance is obliquely vapor-deposited. An alignment film for a characteristic optically anisotropic substance. [7] An optically anisotropic substance obtained by aligning an optically anisotropic substance on the alignment film described in [1], [2], [3], [4], [5] or [6]. . [8] An optical system in which the alignment films described in [1], [2], [3], [4], [5] or [6] are opposed to each other and an optically anisotropic substance is aligned therebetween. Anisotropy.

[9] An optically anisotropic substance, characterized in that the optically anisotropic substance according to [7] or [8] is oriented obliquely with respect to the surface of the substrate. [10] In a liquid crystal display cell in which two alignment films are opposed to each other and an optically anisotropic substance is aligned therebetween, and the orientation of the optically anisotropic substance is controlled by an electric field applied between the alignment films, At least one of the alignment films is [1],
A liquid crystal cell, which is the alignment film as described in [2], [3], [4], [5] or [6]. [11] A liquid crystal display device using the liquid crystal cell according to [10]. [12] The above [7], [8] or

A liquid crystal display device using the optically anisotropic body according to [9]. Next, the present invention will be described in detail.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The alignment film for an optically anisotropic substance of the present invention has the general formula (1).

Embedded image (In the formula, X represents a hydrocarbon group having 1 to 20 carbon atoms or a sulfur atom. R represents a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms or a halogen-containing hydrocarbon group having 1 to 6 carbon atoms,
a is an integer of 0 to 4 and represents the number of substituents. However, multiple R
And a may independently have different substituents and values. ) And a diamino compound represented by the general formula (2)

Embedded image (In the formula, Y represents a tetravalent organic group having 2 or more carbon atoms.) A resin composition containing polyimide as a main component obtained by reacting a tetracarboxylic dianhydride is formed into a film. , Orientated.

In the general formula (1), examples of the halogen atom used as R include fluorine, chlorine, bromine and iodine, and a hydrocarbon group having 1 to 6 carbon atoms and a halogen-containing compound having 1 to 6 carbon atoms. As the hydrocarbon group, methyl,
Hydrocarbon groups such as ethyl, propyl, butyl, pentyl, hexyl linear or branched alkyl groups, cyclohexyl groups, phenyl groups, and groups in which one or more hydrogen atoms of these hydrocarbon groups are substituted with halogen atoms. Is mentioned.

In the general formula (1), the hydrocarbon group having 1 to 20 carbon atoms used as X has 1 to 6 carbon atoms.
And an alkylene group having 2 to 14 carbon atoms, a phenylalkylidene group having 7 to 20 carbon atoms, or a hydrocarbon group having 5 to 20 carbon atoms and containing an alicyclic structure. Representative examples of the alkylene group having 1 to 6 carbon atoms include a methylene group and an ethylene group, and representative examples of the alkylidene group having 2 to 14 carbon atoms include an ethylidene group, a propylidene group, a butylidene group, a pentylidene group and a hexylidene group. Typical examples of a linear or branched alkylidene group such as a heptylidene group and a phenylalkylidene group having 7 to 20 carbon atoms include
Examples thereof include linear or branched phenylalkylidene groups such as phenylmethylidene group, phenylethylidene group, and phenylpropylidene group. Moreover, as a typical example of a C5-C20 hydrocarbon group containing an alicyclic structure, there may be mentioned formulas (b), (c), (d), (e), (f), or (g).

Embedded image And groups in which one or more hydrogen atoms in these alicyclic groups are substituted with an alkyl group such as a methyl group or an ethyl group. Among these, the groups represented by the formulas (b), (c) and (d) are preferable. Furthermore, among the diamino compounds represented by the general formula (1), those represented by the formula (a)

[0008]

Embedded image (In the formula, X represents a butylidene group or a sulfur atom) is also a preferred group of compounds. further,
A group of compounds in which the amino group is para to the substitution position of the ether oxygen atom in the general formula (1) is also a preferred group.

Typical examples of the diamino compounds represented by the general formula (1) are as follows. Bis [4- (4-aminophenoxy) -3-t-butyl-6-methylphenyl] sulfide, bis [3- (4-aminophenoxy)
-3-t-butyl-6-methylphenyl] sulfide,
1,1-bis [4- (4-aminophenoxy) -3-t
-Butyl-6-methylphenyl] butane, 1,1-bis [3- (4-aminophenoxy) -3-t-butyl-6
-Methylphenyl] butane, 1,1-bis [4- (4-
Aminophenoxy) -3-t-butyl-6-methylphenyl] pentane, 1,1-bis [3- (4-aminophenoxy) -3-t-butyl-6-methylphenyl] pentane, 1,1-bis [4- (4-aminophenoxy)-
3-t-butyl-6-methylphenyl] hexane, 1,
1-bis [3- (4-aminophenoxy) -3-t-butyl-6-methylphenyl] hexane, 1,1-bis [4- (4-aminophenoxy) -3-t-butyl-6
-Methylphenyl] heptane, 1,1-bis [3- (4
-Aminophenoxy) -3-t-butyl-6-methylphenyl] heptane, bis [4- (4-aminophenoxy) phenyl] menthane, bis [2- (4-aminophenoxy) phenyl] mentane, 1- [2 -(4-Aminophenoxy) phenyl] -8- [4- (4-aminophenoxy) phenyl] menthane, bis [4- (3-aminophenoxy) phenyl] mentane, bis [2- (3-aminophenoxy) phenyl ] Mentan, 1- [2- (3
-Aminophenoxy) phenyl] -8- [4- (3-aminophenoxy) phenyl] menthane, bis [4- (4
-Aminophenoxy) -3-methylphenyl] menthane, bis [4- (4-aminophenoxy) -3,5-dimethylphenyl] mentane, bis [4- (4-aminophenoxy) -3-butyl-6-methyl Phenyl] menthane, bis [4- (4-amino-5-methylphenoxy)
-3-Methylphenyl] menthane, bis [4- (4-amino-5-methylphenoxy) -3,5-dimethylphenyl] mentane, bis [4- (4-amino-5-methylphenoxy) -3-butyl -6-Methylphenyl] menthane, bis [2- (4-aminophenoxy) -3-methylphenyl] mentane, 1- [2- (4-aminophenoxy) -3-methylphenyl] -8- [4- ( 4-aminophenoxy) -3-methylphenyl] menthane, bis [4- (4-aminophenoxy) phenyl] tricyclo [5,2,1,0 ^2,6 ] decane, bis [2- (4-aminophenoxy) Phenyl] tricyclo [5,2,1,0
^2,6 ] decane, [2- (4-aminophenoxy) phenyl]-[4- (4-aminophenoxy) phenyl] tricyclo [5,2,1,0 ^2,6 ] decane, bis [4- (3
-Aminophenoxy) phenyl] tricyclo [5,2,2]
1,0 ^2,6] decane, bis [2- (3-aminophenoxy) phenyl] tricyclo [5,2,1,0 ^2,6] decane, [2- (3-aminophenoxy) phenyl] - [4
-(3-Aminophenoxy) phenyl] tricyclo [5,2,1,0 ^2,6 ] decane, bis [4- (4-aminophenoxy) -3-methylphenyl] tricyclo [5,2,1,0 ^{2 , 6} ] decane, bis [4- (4-aminophenoxy) -3,5-dimethylphenyl] tricyclo [5,2,1,0 ^2,6 ] decane, bis [4- (4-aminophenoxy) -3 -Butyl-6-methylphenyl]
Tricyclo [5,2,1,0 ^2,6 ] decane, bis [4-
(4-Amino-5-methylphenoxy) -3-methylphenyl] tricyclo [5,2,1,0 ^2,6 ] decane, bis [4- (4-amino-5-methylphenoxy) -3,
5-Dimethylphenyl] tricyclo [5,2,1,0
^2,6 ] decane, bis [4- (4-amino-5-methylphenoxy) -3-butyl-6-methylphenyl] tricyclo [5,2,1,0 ^2,6 ] decane, bis [2- ( 4-
Aminophenoxy) -3-methylphenyl] tricyclo [5,2,1,0 ^2,6 ] decane, [2- (4-aminophenoxy) -3-methylphenyl]-[4- (4-aminophenoxy)- 3-Methylphenyl] tricyclo [5,2,1,0 ^2,6 ] decane and the like are exemplified. Among these, 1,1-bis [4- (4-aminophenoxy) -3-t-butyl-6-methylphenyl] butane,
Bis [4- (4-aminophenoxy) phenyl] menthane and bis [4- (4-aminophenoxy) -3,5
-Dimethylphenyl] tricyclo [5,2,1,
0 ^2,6 ] decane is preferred.

The diamino compound represented by the general formula (1) may be mixed with another diamino compound. Representative examples of other diamino compounds include the following. m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, 3,3′-diaminodiphenyl ether, 3,
4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,
4'-diaminodiphenylmethane, 3,3 ', 5,5'
-Tetrabromo-4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenyl sulfide, 3,
4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 1,3-
Examples include bis (4-aminophenoxy) benzene and 1,4-bis (4-aminophenoxy) benzene. These diamino compounds may be used alone or in combination of two or more, but in order to obtain good solubility, the diamino compound represented by the general formula (1) accounts for 70% by weight or more of the total amount of the diamino compound. It is preferable.

The tetracarboxylic acid dianhydride represented by the general formula (2) is applicable as long as it can undergo a condensation reaction with the above diamino compound, and typical examples thereof include the following. Ethylene tetracarboxylic dianhydride,
Cyclopentanecarboxylic acid dianhydride, pyromellitic acid dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic acid dianhydride , 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,
3'-biphenyltetracarboxylic dianhydride, 3,
3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride, 3,3', 4,4'-diphenylhexafluoroisopropylidene tetracarboxylic dianhydride, 4,
4'-oxydiphthalic acid dianhydride, 2,3,6,7-naphthalene tetracarboxylic acid dianhydride, 1,4,5,8-
Naphthalenetetracarboxylic dianhydride, 1,2,5,6
-Naphthalenetetracarboxylic dianhydride, 2,3,6
7-anthracene tetracarboxylic dianhydride, 1,2,
7,8-phenanthracene tetracarboxylic dianhydride,
4- (1,2-dicarboxylethyl) -4-methyl-
1,2,3,4-tetrahydro-1,2-naphthalenedicarboxylic acid dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride,
5- (1,2-dicarboxylethyl) -3-methyl-
1,2,5,6-tetrahydrophthalic acid dianhydride, 6
Examples include -methyl-tricyclo [6,2,2,0 ^2,7 ] -dodeca-6,11-diene-3,4,9,10-tetracarboxylic acid dianhydride. These tetracarboxylic dianhydrides are used alone or in combination of two or more.

As the method for producing a polyimide in the present invention, any method can be applied as long as it can produce a polyimide. Among them, a polyimide is obtained by reacting a diamino compound and a tetracarboxylic dianhydride in a suitable solvent. A method of obtaining a solution of a polyamic acid as a precursor and then thermally ring-closing it in the solution is preferable. The molar ratio of the diamino compound and the tetracarboxylic dianhydride is 1 / 0.5 to 1
/ 2 in the range of 1 and 1 to obtain a high molecular weight product.
The reaction is carried out at a molar ratio close to / 1. Further, in order to control the molecular weight, a method of adding an aromatic monoamine or an aromatic dicarboxylic acid anhydride to make the terminal non-reactive can also be used. Benzoic acid, isoquinoline or the like may be added as a catalyst for promoting the reaction. Further, in order to improve the physical properties of the obtained polyimide, an appropriate reactive or non-reactive additive may be added. The reactive additive is not particularly limited as long as it does not interfere with the desired characteristics, but examples include epoxy resin, thermosetting polyimide resin, phenol resin, resole resin, urethane resin, vinyl group-containing compound, allyl group-containing compound. , Propargyl group-containing compounds, and cyanic acid esters, and these may be used in any combination. Known compounds may be used as the curing agent of the reactive additive as long as they do not interfere with the desired properties. Specific examples include amines, phenols, acid anhydrides, and the like. Further, as a catalyst of the reactive additive, imidazoles, tertiary amines, 4
Examples include primary ammonium salts and phosphine compounds. Specific examples of the tertiary amines include triethylamine, tributylamine, pyridine and quinoline. Examples of the quaternary ammonium salt include tetraethylammonium chloride, tetramethylammonium bromide, benzylammonium chloride and the like. Examples of the phosphine compound include triphenylphosphine. The non-reactive additive is not particularly limited as long as it does not hinder the object of the present invention, but a rubber component or a thermoplastic polymer is exemplified.

Any solvent that can dissolve the above-mentioned diamino compound and tetracarboxylic acid dianhydride can be used as the synthetic solvent for the polyimide used in the present invention. , The following are listed. N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as NMP), N, N-dimethylacetamide, N, N-diethylacetamide, N, N-
Dimethylformamide, dimethyl sulfoxide, N-methyl-ε-caprolactam, N-cyclohexyl-2-
Pyrrolidone, γ-butyrolactone, 1,3-dimethyl-
2-imidazolidinone, tetramethylurea, hexamethylphosphoramide, m-cresol, p-cresol,
o-cresol, xylenol, pyridine, 1,2-dimethoxyethane, tetrahydrofuran, 1,4-dioxane, diglyme, cyclohexane, benzene, toluene, ethylbenzene, xylene, o-xylene, m-xylene, p-xylene, mesitylene, cumene , O-cymene, m-cymene, p-cymene, benzonitrile, nitrobenzene, chlorobenzene and the like. You may use these solvent individually or in mixture of 2 or more types.
The concentration is 1 to 50% by weight, preferably 5 to 20% by weight, which is the sum of the weights of the diamino compound and the tetracarboxylic dianhydride.
Adjust to the extent.

Prior to the production of the polyimide, it is preferable to sufficiently remove the water content in the raw materials and the reaction solvent by a known method and to carry out the reaction under a dry nitrogen stream. The reaction temperature for polyamic acid synthesis is usually 250 ° C. or lower, preferably 60.
It is below ° C. The reaction pressure is not particularly limited and can be carried out at normal pressure. The reaction time varies depending on the type of diamine and dianhydride used, the solvent and the reaction temperature, but is usually 1
0 minutes to 24 hours. By further heating the obtained polyamic acid to 100 to 250 ° C. for imidization,
A polyimide is obtained.

The obtained polyimide may be used by diluting the reaction solution as it is or by diluting it with a suitable solvent, or by pouring the reaction solution into a poor solvent to precipitate the polyimide, filtering and drying, and then re-dissolving in a suitable solvent. If present, a reactive type or non-reactive type additive can be added and used for forming an alignment film. The solvent used here may be any as long as it dissolves the polyimide of the present invention and does not attack the surface of the coating substrate, but as a typical example, N-methyl-2-pyrrolidone (hereinafter, Abbreviated as NMP), N, N-dimethylacetamide, N, N-diethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, N-methyl-ε-caprolactam, N-cyclohexyl-2-pyrrolidone, γ. -Butyrolactone, 1,3-dimethyl-2-imidazolidinone,
Tetramethylurea, hexamethylphosphoramide, m-
Cresol, p-cresol, o-cresol, xylenol, pyridine, 1,2-dimethoxyethane, tetrahydrofuran, 1,4-dioxane, diglyme, cyclohexane, benzene, toluene, ethylbenzene, xylene, o-xylene, m-xylene, p -Xylene,
Mesitylene, cumene, o-cymene, m-cymene, p-cymene, benzonitrile, nitrobenzene, chlorobenzene, methylene chloride and the like are exemplified. Among these, N-methyl-2-pyrrolidone, N, N-diethylacetamide, xylene, toluene, and methylene chloride are preferably used. The polyimide used at this time may be alone or 2
You may mix and use a polyimide more than a kind. In this case, the method of mixing and the state of the polyimide to be mixed are not particularly limited as long as a uniformly mixed film can be formed during film formation.

To form a polyimide film on a substrate, the solution is applied to a uniform thickness by using a known coating means such as a coater, doctor blade, bar coating, spin coating, gravure coating, micro gravure coating and printing. After being applied to, the solvent is evaporated and dried. Also,
The solid content concentration varies depending on the thickness of the polyimide layer to be formed and the coating means, but is preferably 0.1 to 50% by weight from the viewpoint of the viscosity of the coating liquid and the uniformity of the formed film thickness. At this time, the temperature for volatilizing and drying the solvent is appropriately determined depending on the solvent used, but if it is too low, the productivity is poor, and if it is too high, the applied liquid boils and becomes uneven, or the applied substrate is deformed. Therefore, it is preferable that the drying temperature is 20 ° C. or higher and the temperature is lower than the lower one of the glass transition point or softening temperature of the substrate and the boiling point of the applied liquid. The film thickness of the polyimide film formed on the base material is 0.
It is preferably 005 to 10 μm. More preferably, it is 0.01 to 1 μm.

As a method of performing the alignment treatment of the polyimide film, the same method as the alignment treatment of the alignment film for aligning the liquid crystal can be used. For example, SiO ₂ , SiO,
MgO, MgF ₂ , ITO (Indium Tin Oxide), Z
By applying polyimide to a substrate on which a transparent inorganic substance such as nO is obliquely vapor-deposited, rubbing the surface of the polyimide film with a rubbing roll or a cloth or skin material in which fine fibers such as nylon or rayon are flocked. A technique such as orientation can be used. Above all, from the viewpoint of productivity, it is preferable to rub the surface of the alignment film using a rubbing roll.

The material of the base material to which the polyimide is applied is not particularly limited as long as it is not attacked by the polyimide solution at the time of coating, but a polymer film is preferable from the viewpoint of handleability and processability. When the alignment films are opposed to each other and the optically anisotropic substance is aligned therebetween, a polymer film or a glass plate is preferably used from the viewpoint of the smoothness of the surface and the uniformity of the cap. Further, even when the substrate is attacked by the polyimide solution, it can be preferably used as a substrate film as long as a protective layer that is not attacked by the polyimide solution can be formed on the substrate. As the material used as the protective layer, a hardened acrylate hard coat agent or SiO ₂ , SiO, MgO, Mg
Examples thereof include deposits of inorganic substances such as F ₂ , ITO (indium tin oxide), and ZnO. In addition, in order to control the orientation of the optically anisotropic substance oriented on the substrate by an electric field, IT
A transparent conductor or semiconductor exemplified by O (indium tin oxide) or ZnO may be formed on the surface of the base material. For the purpose of orienting the optically anisotropic substance oriented on the substrate obliquely with respect to the substrate surface, SiO ₂ , SiO, Mg
O, MgF ₂ , ITO (indium tin oxide), ZnO
The inorganic transparent substance exemplified in 1. may be obliquely vapor-deposited on the surface of the substrate. In this case, the thickness of the deposit is preferably 10 to 3000 nm from the viewpoint of uniform film forming property and film forming time. More preferably, it is 50 to 500 nm.

When a polymer film is used as a substrate, it is preferable that the polymer does not change its optical properties or shape at the use temperature or the temperature in the assembling step. In particular, a polymer having a glass transition temperature to a certain extent, or a polymer to which a plasticizer is added, a polymer having a fluidity temperature to a certain extent is preferably used. The preferred lower limit of the glass transition temperature or softening temperature of the polymer of the base material is determined within a range where the liquid crystal display device is not deformed such as a change in optical properties or film shrinkage within a temperature range to be exposed when the liquid crystal display device is assembled and used. it can. In particular,
The glass transition temperature or softening temperature required for the substrate is preferably 80 ° C or higher, more preferably 90 ° C or higher. Examples of the polymer satisfying these conditions include polycarbonate, polysulfone, polyarylate, polyether sulfone, cellulose diacetate, cellulose triacetate, ethylene vinyl alcohol copolymer, polyethylene terephthalate, polyethylene naphthalate, and the like, preferably polycarbonate. , Polyarylate, polysulfone, cellulose triacetate, and polyethylene terephthalate.

In the case of the use of an optically anisotropic body, it is preferable to use a polymer having a small birefringence as the base material. However, if it is used in a display system utilizing birefringence, such as a super twist nematic (hereinafter sometimes referred to as STN) type or electric field control birefringence (hereinafter sometimes referred to as ECB) type liquid crystal display device. The birefringence combined with the optically anisotropic substance coated and oriented thereon can take an appropriate value within the range where it can be matched with the liquid crystal cell.

The polymer base material having a small birefringence can be prepared by using a substance having a small intrinsic birefringence or by reducing the molecular orientation at the time of film formation. As a polymer with a small intrinsic birefringence, polymethylmethacrylate,
Polymethacrylic acid derivatives such as poly-n-butyl methacrylate, poly-t-butyl methacrylate and polyglycol methacrylate, polyacrylic acid derivatives such as polyacrylic acid, polymethyl acrylate and polyethyl acrylate, polyvinyl acetate, polyvinyl butyrate, poly Oxymethylphenylsilylene, norbornene-ethylene copolymer (for example, Mitsui Petrochemical Co., Ltd .: trade name APEL, etc.), norbornene resin (for example, Nippon Synthetic Rubber Co., Ltd .: trade name ARTON, etc.), Amorphous polyolefin (eg Nippon Zeon Co., Ltd.)
Manufactured by Torayac Co., Ltd. (trade name: TOYOLAC transparent grade, etc.) and the like. Among these, polymethyl methacrylate, poly-n-butyl methacrylate, poly-t-butyl methacrylate, norbornene-ethylene copolymer, and amorphous polyolefin are preferable.

Further, even if a material having a large intrinsic birefringence is mixed with a polymer having a positive intrinsic birefringence and a polymer having a negative intrinsic birefringence, the apparent intrinsic birefringence should be reduced. You can Examples of the polymer having a positive intrinsic birefringence include polyvinyl chloride, polyvinylidene fluoride, vinylidene fluoride / trifluoroethylene copolymer, polyethylene oxide, polyphenylene oxide, and polycarbonate. Examples of the polymer possessed include polymethylmethacrylate and polystyrene. A polymer having a positive or negative intrinsic birefringence, and a mixture ratio (weight ratio) in which the combination of compatible polymers and the apparent intrinsic birefringence become small is 20:80 for polyphenylene oxide and polystyrene.
~ 30: 70, polyethylene oxide and polymethyl methacrylate 30:70 to 40:60, vinylidene fluoride / trifluoroethylene copolymer and polymethyl methacrylate 5:95 to 15:85, polyvinylidene fluoride and polymethyl 15: 85-2 for methacrylate
For example, 5:75, and polyvinyl chloride and polymethyl methacrylate may be 15:85 to 25:75. Among these, combinations of polyphenylene oxide and polystyrene, which are easily dissolved in a solvent, and combinations of polyethylene oxide and polymethylmethacrylate are preferable.

In order to obtain a film having a small birefringence by reducing the molecular orientation in the substrate, a polymer such as a solvent casting method is dissolved in a solvent to lower the apparent glass transition temperature and a method that does not stress the film. A film forming method is preferably used. Examples of the polymer suitable for the method include polycarbonate, polysulfone, polyarylate, polyether sulfone, cellulose diacetate, cellulose triacetate, polystyrene, ethylene vinyl alcohol copolymer, polyethylene terephthalate, polyethylene naphthalate, and the like. Is polycarbonate,
Examples include polyarylate, polysulfone, cellulose triacetate, polyethylene terephthalate, and polystyrene.

Here, a plasticizer may be added in order to lower the glass transition temperature or softening temperature of the polymer and suppress the orientation. The type and amount of the plasticizer are not particularly limited as long as they do not impair the object of the present invention. Further, an additive may be used for the purpose of imparting mechanical strength to the base material, improving the handling property, and maintaining the thickness of the optically anisotropic substance portion when superposed. The kind and amount of the additive are not particularly limited as long as they do not impair the object of the present invention. Additives are used for the purpose of imparting mechanical strength to these substrates or improving the adhesiveness when they are bonded to a panel of a liquid crystal display device (hereinafter, sometimes referred to as LCD). Good. The type and amount of the additive are not particularly limited as long as the purpose of the present invention is not impaired.

The optically anisotropic substance of the present invention is obtained by orienting an optically anisotropic substance on the alignment film of the present invention. Further, as the optically anisotropic substance of the present invention, there may be mentioned one in which the above-mentioned alignment films of the present invention are opposed to each other and an optically anisotropic substance is aligned therebetween. The optically anisotropic substance in the present invention is a substance capable of having an optically anisotropic structure, such as a liquid crystalline substance or a dichroic dye. Among these, a liquid crystalline substance is preferably used from the viewpoint of easy alignment control.

Further, regarding the state of alignment of the liquid crystal, SiO ₂ , SiO, MgO, MgF ₂ , I between the substrate and the alignment film.
An electric field or magnetic field is provided to change the chemical structure of the side chain of the liquid crystalline substance or the chemical structure of the polyimide resin composition, providing a layer in which a transparent inorganic substance exemplified by TO (indium tin oxide) or ZnO is obliquely vapor-deposited. The liquid crystal can have various known alignment states by using a technique such as cooling or photopolymerizing after alignment between the two and changing the angle formed by the rubbing directions of the facing alignment films. is there. For example, see page 2.2 of “Liquid Crystal Applied Edition” (Koji Okano, Shunsuke Kobayashi, Baifukan, 1990).
It is possible for the liquid crystal molecules to assume the alignment state as shown in FIG. 2.3 on page 55 and FIG. 2.4 on page 56. Examples of the method for orienting the optically anisotropic substance include a method of spontaneously orienting the applied optically anisotropic substance by heating, a method of orienting in an electric field or a magnetic field, and the like. Among these, it is preferable from the viewpoint of equipment and uniformity that the liquid crystal is spontaneously oriented by heating. When the liquid crystal is polymerized after the alignment, existing polymerization methods such as photopolymerization, thermal polymerization and electron beam polymerization may be used. Among these, the method by photopolymerization is preferable from the viewpoint of polymerization time and uniformity.

Examples of the liquid crystal substance used for the optically anisotropic substance include low-molecular liquid crystals, liquid crystal oligomers, and high-molecular liquid crystals. From the viewpoint of alignment property and alignment time, low-molecular liquid crystals or liquid crystal oligomers are preferably used. The liquid crystal phase is also not particularly limited, and various phases such as a nematic phase, a smectic phase, a cholesteric phase and a discotic phase can be taken. The liquid crystal substance may be used as a single component, or a plurality of substances having different molecular weights / structures may be mixed and used.

Regarding the molecular weight of the liquid crystal used, an appropriate one can be selected depending on the use of the optically anisotropic substance. For example, when the optically anisotropic substance is used as a liquid crystal cell for a liquid crystal display device, low molecular weight liquid crystal is preferably used because the response of the enclosed liquid crystalline substance to an electric field is important. When an optically anisotropic substance is used as an optical compensator for a liquid crystal cell, the liquid crystal substance has a low transition temperature and a small change in the optical physical property due to a change in temperature, and the liquid crystal substance cannot withstand use. If it is large, the viscosity of the liquid becomes high and the time required for orientation becomes long, which is not practical. Therefore, when used in a system that does not like the change of the optical property value due to a temperature change, and when using a low-molecular liquid crystal, it has a polymerized group in order to continue to maintain the orientation after polymerization after polymerization. Preferably, one is used. In this case, the number average molecular weight of the liquid crystal is preferably 1200 to 10,000 in terms of polystyrene when it is non-polymerizable, and 10,000 or less when it is polymerizable. When the optical characteristics of the compensating partner change due to temperature change and it is necessary to follow this and perform optical compensation, select a liquid crystalline substance as disclosed in Japanese Patent Application No. 7-26984. Thus, it is also possible to create an optically anisotropic body having such characteristics.

When the substrate is coated with the optically anisotropic substance, when it is coated on one substrate, the coater, doctor blade, bar coat,
It is carried out by applying a known coating means such as spin coating, gravure coating, micro gravure coating and printing to a uniform thickness, and then volatilizing and drying the solvent.
The optically anisotropic substance used for coating is coated as it is or diluted with a solvent that does not attack the polyimide alignment film, depending on the coating means, the viscosity and the target coating thickness. Examples of the solvent include alcohols, ketones, dimethylsulfoxide, petroleum ether, and aliphatic hydrocarbons. Specific examples of alcohols include ethanol, methanol, isopropanol, propanol, butanol and the like. As ketones, acetone,
Methyl ethyl ketone and the like can be mentioned. Hexane etc. are mentioned as an aliphatic hydrocarbon. The concentration of the optically anisotropic substance is appropriately determined depending on the coating method, coating liquid viscosity and coating thickness, but is preferably 5 to 100% by weight. The thickness of the optically anisotropic substance layer is the refractive index anisotropy of the optically anisotropic substance,
Depending on the orientation form and the desired optical physical properties, from the viewpoint of cost and uniformity of the coated product, it is 0.1 to 100 μm.
It is preferred that More preferably, 0.3-1
0 μm.

Further, in the case of encapsulating between the base materials facing each other, another base material is pasted on the above-mentioned one base material, and the above-mentioned one base material is applied. It is exemplified by the method of sticking together the ones that have been made, infiltrating between facing substrates by utilizing the capillary phenomenon,
Known methods can be used. The thickness of the optically anisotropic substance layer is determined by the refractive index anisotropy of the optically anisotropic substance, the orientation form and the desired optical properties, but from the viewpoint of cost and uniformity of the coated product, it is 0.1 to 100 μm. Is preferred. More preferably, it is 0.3 to 10 μm.

A filler made of an inorganic substance such as a polymer or silica may be added to the optically anisotropic substance for the purpose of maintaining the thickness of the layer. The shape, material, size and amount of the filler are not particularly limited as long as they do not impair the object of the present invention. Further, a top coat may be applied on the alignment layer to protect the alignment layer and control the alignment state.

When the optical anisotropic body of the present invention is used as a compensating plate for a liquid crystal cell in a liquid crystal display device, there is no particular limitation on the place or number of the optical anisotropic body, and there is no limitation between the polarizing film and the liquid crystal cell. It can be anywhere. Further, it may be used in combination with an optically anisotropic body obtained by stretching a polymer. The absorption axis of the polarizing film and the angle formed by the rubbing direction of the liquid crystal display cell and the optical axis of the optically anisotropic body are determined so that the contrast and viewing angle characteristics are optimized.

[0033]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. The measuring methods and devices used in the following synthesis examples, examples and comparative examples are as follows. Regarding the physical properties of polyimide, the intrinsic viscosity η _inh. Was calculated by preparing the NMP solution of 0.5 g / dl, measuring the drop time in a constant temperature bath at 30 ° C. using an Ubbelohde viscometer, and calculating by the following formula. η _inh. = [ln (t / t ₀ )] / 0.5 [dl / g] where t: drop time (second) of solution measured by viscometer t ₀ : drop of solvent similarly measured Time (second) Infrared absorption spectrum is IR-70 manufactured by JASCO Corporation
It was measured using a No. 0 device. Liquid crystal compounds, elemental analysis,
The structure was confirmed by infrared absorption spectrum and 1 H-NMR spectrum, and the molecular weight was confirmed by GPC. The retardation of the obtained optically anisotropic film was measured using a Senarmont method with a polarizing microscope [OPTIPHOTO2-POL, manufactured by Nikon Corporation]. The wavelength of the measurement light is 546 nm. The retardation value when tilted was determined from the value when the tilt stage was attached to the polarizing microscope and the sample was tilted in the rubbing direction of polyimide or in the same plane as and perpendicular to the rubbing direction. The temperature dependence of the retardation was determined by measuring the retardation while heating the obtained optically anisotropic film on a hot stage (Mettler, trade name: FP82 hot stage).

Synthesis Example 1 1,2-bis [4- (4-aminophenoxy) -3-t-butyl-6-, was placed in a 2-liter four-necked flask equipped with a nitrogen gas inlet tube, a thermometer, and a stirrer. 197.4 g (0.35 mol) of methylphenyl] butane and NMP10
76.3 g (0.35 mol) of pyromellitic dianhydride was charged to the place where 29.6 g of the compound had been charged and dissolved, and the mixture was stirred overnight at room temperature under a nitrogen stream to obtain a polyamic acid solution.
The intrinsic viscosity of the obtained polyamic acid was 1.16 dl / g. Next, the polyamic acid solution is heated to 190 ° C.,
The mixture was stirred in a nitrogen stream for 7 hours (the generated water was removed to the outside of the system together with nitrogen) for imidization to obtain an NMP solution of polyimide. The reaction solution was dropped into methanol with vigorous stirring, and the powdery polyimide deposited was collected by filtration and dried to obtain a polyimide powder. 1650cm The infrared absorption spectrum of the polyimide was measured for an absorption around 5 membered 1720 cm ^-1 and 1780 cm ^-1 which is the characteristic absorption band of the cyclic imide group is observed, derived from an amide group
^No absorption around ^-1 was observed, confirming the completion of imidization.
The intrinsic viscosity of the obtained polyimide was 0.73 dl / g.

Synthesis Example 2 Cyclic pentasiloxane liquid crystals were prepared by reacting vinyl monomers (3) and (4) with pentamethylcyclopentasiloxane at a mixing ratio of 7: 3 in the same manner as described in JP-B-63-41400. An oligomer was obtained.

Embedded image

Embedded image The glass transition temperature of the selected liquid crystal oligomer is 14 ° C., the transition temperature to the isotropic phase is 114 ° C., 14 ° C. to 114 ° C.
Showed a cholesteric phase. Further, as a result of extrapolation from the measured value of the selective reflection wavelength of the composition of the liquid crystal oligomer and the nematic liquid crystal, the selective reflection wavelength of the liquid crystal oligomer alone was 280 nm. From this wavelength, the cholesteric phase spiral pitch of this liquid crystal oligomer is calculated to be 0.2 μm.

Example 1 The powdery polyimide obtained in Synthesis Example 1 was dissolved in toluene to prepare a 2% toluene solution. This was spin-coated on a triacetyl cellulose substrate hard-coated with an ester acrylate-based hard coating agent to obtain a polyimide film having a thickness of 0.15 μm. The surface of this film was rubbed with a rubbing roll in which a large number of fine nylon fibers were flocked to obtain a polyimide alignment film. A 30% acetone solution of 4-pentyl-4′-cyanobiphenyl was spin-coated on this. 4-pentyl-4′-cyanobiphenyl has a nematic orientation parallel to the rubbing direction,
The retardation value measured from the film normal direction is 8
It was 24 nm.

Example 2 4- (allyl-oxy) -benzoic acid-4'-methoxyphenyl ester was reacted with pentamethylcyclopentasiloxane in the same manner as described in JP-B-63-41400. A membered-ring pentasiloxane liquid crystal polymer was obtained. This liquid crystal exhibited a nematic layer.

A 30% acetone solution of the liquid crystal polymer was spin-coated on the same substrate as in Example 1. When the substrate was heated to 60 ° C., the molecules had a nematic orientation parallel to the rubbing direction. The retardation value measured from the film normal direction was 654 nm.

Example 3 The liquid crystal oligomer of Synthesis Example 2 was dissolved in acetone to a concentration of 30%, and 2.0 g by weight of Irgacure-907 (manufactured by Ciba-Geigy) as a photopolymerization initiator was added to the liquid crystal oligomer. Mixed so that This solution was spin-coated on the same substrate as in Example 1. When this substrate was heated to 80 ° C., it showed cholesteric orientation. The retardation value of the film is shown in Table 1.

Example 4 4- (allyl-oxy) -benzoic acid-4'-methoxyphenyl ester and pentamethylcyclopentasiloxane were reacted in the same manner as in JP-B-63-41400 to give a 5-membered ring. A pentasiloxane liquid crystal polymer was obtained.
The 5-membered ring pentasiloxane liquid crystal polymer and the liquid crystal oligomer of Synthesis Example 2 were mixed at a ratio of 1: 1. The mixture was dissolved in acetone to obtain a 30 wt% acetone solution of the mixture. The acetone solution was spin-coated on the same substrate as in Example 1. When this substrate was heated to 80 ° C., cholesteric orientation was observed and green selective reflection was observed.

Example 5 The powdery polyimide obtained in Synthesis Example 1 was dissolved in toluene to prepare a 2% toluene solution. This was spin-coated on a glass substrate on which SiO ₂ was vapor-deposited at a thickness of 150 nm obliquely from the substrate surface normal direction by 80 degrees to obtain a polyimide alignment film. 4- (allyl-oxy) -benzoic acid-4'-methoxyphenyl ester and pentamethylcyclopentasiloxane are reacted in the same manner as the method described in JP-B-63-41400 to give a 5-membered pentasiloxane liquid crystal polymer. Obtained. This liquid crystal exhibited a nematic layer. A 30% acetone solution of the above liquid crystal polymer was spin-coated on the polyimide alignment film. When this substrate was heated to 60 ° C., the molecules were oriented such that the projection of the molecules on the substrate surface was parallel to the rubbing direction and was inclined by 30 ° with respect to the substrate surface.
The retardation value of the film is shown in Table 1.

Example 6 The powdery polyimide obtained in Synthesis Example 1 was dissolved in toluene to prepare a 2% toluene solution. This was spin-coated on an ITO glass substrate to obtain a polyimide film. The surface of this film was rubbed with a rubbing roll to obtain a polyimide alignment film. Face this substrate so that the rubbing directions are parallel to each other, and insert a 6 μm silica spacer between them.
4-Pentyl-4′-cyanobiphenyl added with wt% was encapsulated. 4-pentyl-4′-cyanobiphenyl has a nematic orientation parallel to the rubbing direction,
Coloring due to birefringence was observed under crossed Nicols. I
When a voltage was applied to the TO, the 4-pentyl-4′-cyanobiphenyl molecules were oriented in the substrate normal direction, and the transmitted light under crossed Nicols became a very weak white color.

Comparative Example 1 0.54 g of p-phenylenediamine was placed in a 2-liter four-necked flask equipped with a nitrogen gas introducing tube, a thermometer and a stirrer.
(5.5 mmol) and 18.0 g of NMP were charged and dissolved, and then biphenyl-3,4,3 ', 4'-.
Tetracarboxylic acid-3,4; 3 ', 4'-dianhydride 1.
47 g (5.5 mmol) was charged and stirred overnight at room temperature under a nitrogen stream to obtain a polyamic acid NMP solution. This solution was diluted 5-fold with NMP, and this was spin-coated on a triacetyl cellulose substrate hard-coated with an ester acrylate-based hard coating agent. For imidization,
During firing at 200 ° C., the triacetyl cellulose base material contracted, deformed and turned yellow, and could not be used as a base material for orienting an optically anisotropic substance. In order to suppress the deformation of the triacetyl cellulose substrate, it was baked at 100 ° C. for 3 hours, but imidization could not be sufficiently advanced.

[0044]

[Table 1]

The axis of rotation at the time of tilting was perpendicular to the rubbing direction of the film or the oblique deposition direction of the substrate surface and parallel to the alignment film. The sign of the inclination angle is positive when the rubbing start side of the substrate or the side close to the vapor deposition source is inclined toward you. The sign of the phase difference was positive when the component oscillating parallel to the rubbing direction of the film or the oblique deposition direction of the substrate surface with respect to the linearly polarized light incident on the film lags behind the component oscillating perpendicularly thereto.

[0046]

The alignment film for an optically anisotropic substance of the present invention comprises:
A film can be formed by a low-temperature process that can withstand a general-purpose polymer while maintaining the excellent physical properties peculiar to polyimide. In particular, a film can be formed below the glass transition temperature of a polymer such as polycarbonate, cellulose triacetate or polyether sulfone. Further, by using the alignment film, an optical anisotropic body in which an optically anisotropic substance is aligned and a liquid crystal display device using the same, which is excellent in viewing angle characteristics, are provided at low cost without complicated steps. You can

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Mitsuhiro Shibata 6 Kitahara, Tsukuba, Ibaraki Sumitomo Chemical Co., Ltd.

Claims (12)

[Claims] 1. A compound of the general formula (1) (In the formula, X represents a hydrocarbon group having 1 to 20 carbon atoms or a sulfur atom. R represents a halogen atom, a hydrocarbon group having 1 to 6 carbon atoms or a halogen-containing hydrocarbon group having 1 to 6 carbon atoms,
a is an integer of 0 to 4 and represents the number of substituents. However, multiple R
And a may independently have different substituents and values. ) And a diamino compound represented by the general formula (2): (In the formula, Y represents a tetravalent organic group having 2 or more carbon atoms.) A main component is a polyimide obtained by reacting a tetracarboxylic dianhydride represented by Alignment film for isotropic substances. 2. A diamino compound represented by the general formula (1) is represented by the following formula (a): (In the formula, X represents a butylidene group or a sulfur atom.) The alignment film for an optically anisotropic substance according to claim 1. 3. In the general formula (1), X is the formula (b),
(C) or (d) The alignment film for an optically anisotropic substance according to claim 1, which is represented by: 4. An alignment film for an optically anisotropic substance, characterized in that the alignment film according to claim 1, 2 or 3 is formed on a polymer film. 5. An alignment film for an optically anisotropic substance, wherein the alignment film according to claim 1, 2, 3 or 4 is formed on a conductor or a semiconductor. 6. An optical anisotropy characterized in that the alignment film according to claim 1, 2, 3, 4 or 5 is coated on a substrate on which an inorganic transparent substance is obliquely vapor-deposited. Alignment film for substances. 7. An optical anisotropic body obtained by orienting an optically anisotropic substance on the alignment film according to claim 1, 2, 3, 4, 5 or 6. 8. An optical anisotropic body obtained by aligning the alignment films according to claim 1, 2, 3, 4, 5 or 6 and aligning an optically anisotropic substance therebetween. 9. An optically anisotropic substance, characterized in that the optically anisotropic substance according to claim 7 or 8 is oriented obliquely with respect to the surface of the substrate. 10. A liquid crystal cell in which two alignment films are opposed to each other and an optically anisotropic substance is aligned therebetween, and the alignment of the optically anisotropic substance is controlled by an electric field applied between the alignment films, At least one of the alignment films is defined by claim 1.
A liquid crystal cell, which is the alignment film described in 2, 3, 4, 5 or 6. 11. A liquid crystal display device using the liquid crystal cell according to claim 10. 12. A liquid crystal display device using the optical anisotropic body according to claim 7.