JP2000001614A - Liquid crystal orientating agent and liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal orientating agent useful for providing a liquid crystal orientated film for a liquid crystal display element having a TN type sequence cell by including a specific soluble polyimide. SOLUTION: This liquid crystal orientating agent contains a soluble polyimide having a structural unit of formula I (R1 is a bifunctional organic group; R2 is fluorine or a monofunctional organic group; (a) is 0-2). The structural unit of formula I is obtained by bringing preferably 0.6-2.4 mols of a tetracarboxylic acid dianhydride of formula II into contact with 1 mol of a diamine compound of the formula H2N-R1-NH2 (e.g. paraphenylenediamine or the like) in an organic solvent preferably at 0-100 deg.C to form a polyamic acid and then heating the formed polyamic acid in an organic solvent preferably at 100-170 deg.C or imidating the polyamic acid in the presence of both a dehydrating agent (e.g. acetic anhydride or the like) and a basic catalyst (e.g. pyridine or the like) preferably at 60-150 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal aligning agent and a liquid crystal display device. More specifically, the present invention relates to a liquid crystal aligning agent which can be suitably used for providing a liquid crystal alignment film of a liquid crystal display element having a TN type array cell (hereinafter referred to as a TN type display element), and a liquid crystal display element using the same.

[0002]

2. Description of the Related Art Conventionally, a nematic liquid crystal having a positive dielectric anisotropy is sandwiched between substrates having a transparent electrode having a liquid crystal alignment film made of polyimide or the like, and the major axis of the liquid crystal molecules is continuous at 90 degrees between the substrates. 2. Description of the Related Art A liquid crystal display element (TN-type display element) having a TN-type alignment cell which is twisted likewise is known. The alignment of the liquid crystal in this TN type display element is formed by a liquid crystal alignment film subjected to a rubbing treatment.

However, in a conventional liquid crystal alignment film using polyimide, since the polyimide is insoluble in an organic solvent, an organic solvent-soluble polyamic acid, which is a precursor of the polyimide, is applied to a substrate with a transparent electrode.
It has been prepared by heating to ~ 350 ° C and converting to polyimide on the substrate.

However, when stored as an organic solvent solution, the polyamic acid has poor storage stability such as precipitation of insoluble components or a decrease in viscosity, and when converted to polyimide, it is heated to a relatively high temperature as described above. Therefore, there is a disadvantage that it is necessary to consider heat resistance of other elements and components. In order to avoid the latter disadvantage, the conversion and baking of the polyamic acid to the polyimide is 150-
Although it can be carried out at a temperature of 250 ° C., in such a case, the imidization is insufficient and a carboxyl group remains, which causes a new problem that the carboxyl group disturbs the orientation of liquid crystal molecules. JP-A-61-205924 discloses the following formula:

[0005]

Embedded image Here, R ⁴ is a divalent organic acid.

There is disclosed a liquid crystal display device provided with a liquid crystal alignment film made of polyimide having a monomer unit represented by the following formula. This polyimide has the advantage that it is soluble in an organic solvent and can be applied as an organic solvent solution.

[0007]

An object of the present invention is to provide a novel liquid crystal aligning agent containing a polyimide soluble in an organic solvent. Another object of the present invention is to provide a novel liquid crystal aligning agent that provides a liquid crystal alignment film that produces good alignment of liquid crystals.

It is still another object of the present invention to provide a novel liquid crystal aligning agent which can be fired at a temperature of 200 ° C. or less to provide an excellent liquid crystal alignment film as described above. Still another object of the present invention is to provide a liquid crystal display device using the liquid crystal aligning agent of the present invention. Still other objects and advantages of the present invention will be apparent from the following description.

[0009]

According to the present invention, the above objects and advantages of the present invention are firstly achieved by the following formula (1).

[0010]

Embedded image Wherein R ¹ is a divalent organic group, R ² is a fluorine atom or a monovalent organic group, and a is an integer of 0 to 2,

This is achieved by a liquid crystal aligning agent characterized by containing a soluble polyimide having a structural unit represented by the following formula (hereinafter referred to as “polymer (I)”). Secondly, the above objects and advantages of the present invention are achieved by a liquid crystal display device having a liquid crystal alignment film comprising the liquid crystal alignment agent of the present invention. The structural unit represented by the above formula (1) is represented by the following formula (1) -a

[0012]

Embedded image Here, the definitions of R ² and a are the same as in the above formula (1).

The tetracarboxylic dianhydride represented by the following formula (1) -b H ₂ NR ¹ -NH ₂ (1) -b wherein R ¹ is defined by the above formula (1) It can be produced by using the same diamine compound represented by as a starting material and reacting both.

In the above diamine compound of the formula (1) -b, R ^{1 in the} formula (1) -b is a divalent organic acid, preferably a divalent aromatic group, an aromatic group having a hetero atom, Examples thereof include an aliphatic group having an aliphatic group, an alicyclic group, and an organosiloxy group.

Examples of such diamine compounds include paraphenylenediamine, metaphenylenediamine,
4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone,
4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,4'-diaminobenzanilide, 3,4 '
-Diaminodiphenyl ether, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,
4'-diaminobenzophenine, 2,2-bis [4-
(4-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] hexafluoropropane, bis [4- (4-aminophenoxy) phenyl] sulfone, 1,4-bis (4-aminophenoxy ) Benzene, 1,3-bis (4-aminophenoxy)
Benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) -10-hydro-anthracene, 9,9-bis (4-aminophenyl) fluorene, 4,4 ' -Methylene-bis (2-chloroaniline), 2,2 ', 5,5'-tetrachloro-4,
4'-diaminobiphenyl, 2,2'-dichloro-4,
4'-diamino-5,5'-dimethoxybiphenyl, 3,
3'-dimethoxy-4,4'-diaminobiphenyl, 2,
Aromatic diamines such as 2-bis (4-aminophenyl) hexafluoropropane and 4,4'-diaminobenzanilide; aromatic diamines having a hetero atom such as diaminotetraphenylthiophene; 1,1-metaxylylenediamine 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane,
Isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-methanoindanylene dimethylenediamine, tricyclo [6,2,1,0
^2.7 ]-aliphatic or cycloaliphatic diamines such as undecylenedimethyldiamine; and

[0016]

Embedded image

Wherein R ³ is an alkyl group having 1 to 12 carbon atoms such as a methyl group, an ethyl group or a propyl group, a cycloalkyl group such as a cyclohexyl group, or an aryl group such as a phenyl group; And q represents an integer of 1 to 20).

Among these, paraphenylenediamine,
Metaphenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 2,
2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis (4-aminophenyl) hexafluoropropane, 4,4'-diaminobenzanilide, bis [4- (4-aminophenoxy) ) Phenyl] hexafluoropropane, 9,9-bis (4-aminophenyl)
Fluorene is preferred.

The reaction of the tetracarboxylic dianhydride of the above formula (1) -a with the diamine compound of the above formula (1) -b is as follows:
First, both compounds are brought into contact in an organic solvent to produce a polyamic acid, and then the resulting polyamic acid is imidized by heating it in an organic solvent as it is or by treating it in the presence of a dehydrating agent and a basic catalyst. Can be implemented.

The tetracarboxylic dianhydride and the diamine compound are usually used in an amount of 0.4 to 4 mol of the tetracarboxylic dianhydride per 1 mol of the diamine compound.
Preferably it is used in a proportion of up to 2.4 mol. The reaction for producing a polyamic acid is usually carried out at a temperature of 0 to 150 ° C, preferably 0 to 100 ° C. The reaction solvent used was a total amount of tetracarboxylic dianhydride and diamine compound of 0.1.
It is used so as to have a concentration of ３０30% by weight.

The reaction temperature for imidizing the polyamic acid obtained by the above reaction in an organic solvent is usually from 60 to 200 ° C, preferably from 100 to 170 ° C. If the temperature is lower than 60 ° C., the progress of the imidization reaction is delayed, and 2
If it exceeds 00 ° C., the molecular weight of the polyimide compound may decrease. The reaction temperature for imidization in the presence of a dehydrating agent and a basic catalyst is usually 0 to 180 ° C, preferably 60 to 150 ° C. As the dehydrating agent, for example, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride 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.

The basic catalyst is not particularly limited. For example, tertiary amines such as pyridine, collidine, lutidine and triethylamine can be used. The amount of the basic catalyst used is 0.5 to 1 per mol of the dehydrating agent used.
0 mole is preferred.

The organic solvent used in the imidation reaction is not particularly limited as long as it can dissolve the imidation product. For example, N-methyl-2-pyrrolidone, N, N-
Non-protonic polar solvents such as dimethylacetamide, N, N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphoryltriamide, phenolic solvents such as m-cresol, xylenol, phenol and halogenated phenol Can be mentioned.

The thus obtained polymer (I) used in the present invention has an intrinsic viscosity [ηinh = ln (ηrel / C), in N-methyl-2-pyrrolidone, C = 0.5 / dl, 30 ° C.] Is preferably 0.05 to 10 dl / g, more preferably 0.05 to 10 dl / g.
Those having 5 to 5 dl / g are more preferable.

The liquid crystal aligning agent of the present invention comprises a polymer (I)
It preferably comprises an organic solvent solution. The organic solvent solution is
The solid content concentration is preferably 0.1 to 30% by weight, more preferably 0.5 to 20% by weight.

Examples of the organic solvent to be used include an organic solvent which can be used in the above imidization reaction and a mixed solvent thereof with a general organic solvent as described below. That is, general organic solvents such as alcohols, ketones, esters, ethers, halogenated hydrocarbons, and hydrocarbons such as methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 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, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1,4- Dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, benzene, toluene, xylene and the like can be used. Naturally, these general organic solvents are used in such a ratio that the polymer (I) is not precipitated. The liquid crystal aligning agent of the present invention may contain a functional silane-containing compound or a titanate in addition to the polymer (I) for the purpose of improving adhesiveness to a substrate.

As the functional silane-containing compound, for example, 3
-Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane,
N- (2-aminoethyl) -3-amino-propyltrimethoxysilane, N- (2-aminoethyl) -3-amino-propylmethyldimethoxysilane, 3-ureido-
Propyltrimethoxysilane, 3-ureido-propyltriethoxysilane, N-ethoxycarbonyl-3-amino-propyltrimethoxysilane, N-ethoxycarbonyl-3-amino-propyltriethoxysilane, N
Trimethoxysilylpropyl-triethylenetriamine, N-triethoxysilylpropyl-triethylenetriamine, 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-amino-propyltriethoxysilane, N-phenyl-3-
Amino-propyltrimethoxysilane, N-phenyl-
Examples thereof include 3-amino-propyltriethoxysilane, N-bis (oxyethylene) -3-aminopropyltrimethoxysilane, and N-bis (oxyethylene) -3-amino-propyltriethoxysilane. These can be used alone or in combination of two or more.

Examples of the titanate compound include isopropyl triisostearoyl titanate, isopropyl trimiristil titanate, bis (triethanolamine) diisopropyl titanate, and bis (triethanolamine) dibutyl titanate. These titanates can be used alone or in combination of two or more. In the present invention, a liquid crystal display device using the liquid crystal alignment agent of the present invention is also provided.

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. First, the liquid crystal aligning agent of the present invention is applied to the transparent conductive film side of the substrate on which the transparent conductive film is provided by a roll coater method, a spinner method, a printing method, or the like.
C., more preferably at a temperature of 120 to 200.degree. C. to form a coating film. The thickness of this coating film is usually 0.00
It is 1 to 1 μm, preferably 0.005 to 0.5 μm.

The formed coating film is made of the polymer (I), and is subjected to a rubbing treatment with a roll around which a cloth made of synthetic fiber such as nylon is wound, thereby forming a liquid crystal alignment film. As the substrate, for example, float glass, glass such as soda glass, polyethylene terephthalate,
Polybutylene terephthalate, polyether sulfone,
A transparent substrate made of a plastic film such as polycarbonate can be used.

As the transparent conductive film, a NESA film made of SnO ₂ , an ITO film made of In ₂ O ₃ —SnO ₂ and the like can be used. For the patterning of these transparent conductive films, a photo-etching method, a method using a mask in advance, or the like is used. When applying the liquid crystal alignment agent, a functional silane-containing compound, titanate, or the like may be applied on the substrate and the transparent conductive film in advance to further improve the adhesion between the substrate and the transparent conductive film. it can.

The substrates having the liquid crystal alignment film formed thereon are opposed to each other so that the surfaces of the liquid crystal alignment films are orthogonal or antiparallel to the rubbing direction, and the peripheral portion between the substrates is sealed with a sealant. And filling the filling port to form a liquid crystal cell,
A liquid crystal display device is obtained by laminating a polarizing plate on both surfaces of the substrate such that the polarization directions thereof coincide with or perpendicular to the rubbing direction of the liquid crystal alignment film of the substrate.

As the sealant, for example, an epoxy resin containing a hardener and aluminum oxide spheres as spacers can be used. As the liquid crystal, a liquid crystal that forms a nematic liquid crystal is preferably used. For example, Schiff base liquid crystal, 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, and Cuban-based liquid crystal are used.

In addition, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonaate and cholesteryl carbonate, and trade names C-15, C-15
A chiral agent or the like sold as B-15 (manufactured by British Drag House) can also be used. Furthermore, p-decyloxybenzylidene-
Ferroelectric liquid crystals such as p'-amino-2-methylbutylcinnamate can also be used.

As the polarizing plate used outside the liquid crystal cell, a polarizing plate in which a polarizing film called an H film in which polyvinyl alcohol is stretched and oriented and iodine is absorbed by a cellulose acetate protective film or the H film itself is used. And the like.

[0036]

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 addition, the orientation of the liquid crystal cell was evaluated by turning on the voltage.
The presence or absence of an abnormal domain (reverse twist / reverse tilt) in the liquid crystal cell when the liquid crystal cell was turned off was observed with a polarizing microscope.

Synthesis Example 1 19.7 g of 4,4'-diaminodiphenylmethane was dissolved in 366 g of γ-butyrolactone, and the mixture was sufficiently stirred at 25 ° C., and then bicyclo [2.2.2] oct-7-enetetracarboxylic acid was dissolved. 24.8 g of dianhydride was added and reacted at 60 ° C. for 5 hours. Next, 39.5 g of pyridine and 30.6 g of acetic anhydride were added and reacted at 120 ° C. for 3 hours. Next, the reaction solution was poured into a large excess of methanol to precipitate a reaction product, which was washed with methanol, and then reduced under reduced pressure at 40 ° C. for 15 minutes.
After drying for an hour, 31.1 g of a polymer (Ia) having an intrinsic viscosity of 1.15 dl / g was obtained. The infrared absorption spectrum of the obtained polymer (Ia) (KBr pellet method) were measured, an imido group characteristic absorption in 1720 cm ^-1 and 1780 cm ^-1 was observed, it was confirmed that the polyimide.

Synthesis Example 2 In Synthesis Example 1, the tetracarboxylic dianhydride was changed to 21.8 g of pyromellitic dianhydride and reacted at 0 ° C. for 3 hours. The reaction was then washed with a large excess of methanol,
Dry under reduced pressure at 40 ° C for 15 hours to obtain an intrinsic viscosity of 1.51d
31.1 g of 1 / g polyamic acid were obtained.

Example 1 6.12 g of the polymer (1a) obtained in Synthesis Example 1 was
It was dissolved in 146.9 g of methyl-2-pyrrolidone to prepare a solution having a solid content of 4% by weight. This solution was added with a pore size of 1μ.
The mixture was filtered with a filter of m to prepare a liquid crystal aligning agent solution. This solution was applied to the transparent electrode surface on a glass substrate with a transparent electrode made of an ITO film using a spinner and dried at 180 ° C. for 1 hour to form a coating film having a dry film thickness of 0.05 μm. A rubbing machine having a roll in which a nylon-type cloth is wound around the formed coating film has a roll rotation number of 500.
The rubbing treatment was performed at a rpm of 1 cm / sec.

Next, the outer edge of each of the pair of rubbed substrates on the side having the liquid crystal alignment film has a diameter of 17 μm.
After the epoxy resin adhesive containing aluminum oxide spheres was screen-printed and applied, a pair of substrates was overlapped with each other vertically so that the rubbing directions were orthogonal to each other and pressed to cure the adhesive. Next, between the pair of substrates from the liquid crystal injection port,
After filling a nematic liquid crystal (ZLI-1132, manufactured by Merck), the liquid crystal injection port is sealed with an epoxy-based adhesive, and a polarizing plate is provided on both outer surfaces of the obtained device. The substrates were bonded together so as to match the rubbing direction of the liquid crystal alignment film on the substrate, thereby producing a liquid crystal display device.
When a voltage was applied to the obtained liquid crystal display device, favorable display without occurrence of abnormal domains was obtained.

Comparative Example 1 Using the polyamic acid obtained in Synthesis Example 2, a liquid crystal display device was produced in the same manner as in Example 1. When voltage was applied to the obtained liquid crystal display device, abnormal domains were observed along the rubbing direction.

[0042]

According to the liquid crystal aligning agent of the present invention, 200 ° C.
Firing at the following temperatures is possible. Since this liquid crystal alignment agent has good liquid crystal alignment properties, it can be suitably used particularly for TN type display devices. A liquid crystal display device having an alignment film made of polyimide formed using the liquid crystal alignment agent of the present invention can be suitably used for a ferroelectric display device by selecting a liquid crystal to be used. further,
A liquid crystal display device having a liquid crystal alignment film formed by using the liquid crystal alignment agent of the present invention has excellent liquid crystal alignment and reliability. For example, a desk calculator, a wristwatch, a clock, a coefficient display plate, a word processor, and a personal computer ,
It is particularly useful for display devices such as liquid crystal televisions.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kimiyasu Sano 2--11-24 Tsukiji, Chuo-ku, Tokyo Inside JSR Co., Ltd. (72) Inventor Yasuyama Yasuaki 2-11-24 Tsukiji, Chuo-ku, Tokyo JSR Inside the corporation

Claims (2)

[Claims] [Claim 1] The following formula (1) Wherein R ¹ is a divalent organic group, R ² is a fluorine atom or a monovalent organic group, and a is an integer of 0 to 2,
A liquid crystal aligning agent comprising a soluble polyimide having a structural unit represented by: 2. A liquid crystal display device comprising a liquid crystal alignment film comprising the liquid crystal alignment agent according to claim 1.