JPH09197411A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal display element of a lateral electric field method having excellent visual characteristics, especially having a large angle of view field by constituting electrodes to generate an electric field almost parallel to the substrates and using a specified alignment layer. SOLUTION: Two substrates having alignment layers for a liquid crystal are disposed with the alignment layers facing each other. Each substrate consists of a substrate, an electrode to form display pixels on the substrate, and an alignment layer formed directly on the display pixels or with an insulating film interposed. A liquid crystal layer is held between these substrate having alignment layers. The electrodes are designed to generate an electric field almost parallel to the substrates. Moreover, the alignment layer is formed by irradiating a coating film of polyimide and/or polyamic acid with polarized UV rays and has 0 deg. to 0.1 deg. pretilt angle. By this method, a liquid crystal display element having excellent visual characteristics can be obtd. Since deposition of dust or breaking of TFT element due to electrostatic charges during a rubbing treatment by a conventional method is prevented, the alignment layers can be produced at a high production yield.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a liquid crystal display device. More specifically, the present invention relates to a horizontal electric field type liquid crystal display device having excellent visual characteristics.

[0002]

2. Description of the Related Art Conventionally, in a TN (Twisted Nematic type) liquid crystal display element, a transparent electrode facing the interface between two substrates is used as an electrode for driving the liquid crystal, and the direction of the electric field applied to the liquid crystal is changed to the substrate surface. A method of making the direction perpendicular to (a vertical electric field method or a vertical electric field control type) is adopted. This vertical electric field type liquid crystal display device has a drawback that the visual characteristics are poor due to the difference in refractive index between the long axis and the short axis of the liquid crystal molecules, which is a major obstacle to increasing the screen size. In order to improve the visual characteristics due to the refractive index of the liquid crystal molecules, a method in which an electric field applied to the liquid crystal is in a direction parallel to the substrate interface (called a lateral electric field method or a lateral electric field control type) is effective. As this lateral electric field method, a method using a comb-shaped electrode pair is disclosed in, for example, JP-A-56-91277 or JP-A-1-120528.
No. proposed. However, since the characteristics of the alignment film are insufficient, a horizontal electric field type liquid crystal display device has not yet been put into practical use.

[0003]

In the horizontal electric field type liquid crystal display device, stable display cannot be achieved unless the angle between the long axis of the liquid crystal molecule and the electrode surface is reduced. Therefore, in the liquid crystal alignment film, it is necessary to reduce the angle between the alignment film surface and the long axis of the liquid crystal molecules, that is, the pretilt angle.
Generally, in order to reduce the pretilt angle of liquid crystal, a liquid crystal alignment film is strongly rubbed in one direction with a buff cloth, but it is extremely difficult to obtain a pretilt angle of 1 ° or less, for example. Further, when the alignment film is physically strongly rubbed, peeling or misalignment of the film occurs, which also causes a decrease in the yield of liquid crystal display device manufacturing. An object of the present invention is to provide a lateral electric field type liquid crystal display device having excellent visual characteristics, particularly a large viewing angle.

[0004]

According to the present invention, a substrate,
Two liquid crystal alignment film holding substrates each composed of a display pixel formed on the substrate by electrodes and a liquid crystal alignment film formed on the display pixel directly or via an insulating film are arranged so that the alignment films face each other. A liquid crystal display element in which a liquid crystal layer is sandwiched between two alignment film holding substrates, the electrodes being configured to generate an electric field substantially parallel to the substrates, and the alignment film And a polyimide and / or polyamic acid coating film irradiated with polarized ultraviolet rays, wherein the alignment film has a pretilt angle of 0 ° to 0.1 °. .

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. As the liquid crystal aligning agent used for obtaining the coating film of polyimide and / or polyamic acid for forming the liquid crystal aligning film used in the present invention, polyamic acid and / or imidized polymer of polyamic acid is preferably used. . The polyamic acid is obtained by reacting a tetracarboxylic dianhydride and a diamine compound, and the imidized polymer is obtained by subjecting the obtained polyamic acid to a dehydration ring closure.

[Tetracarboxylic acid dianhydride] The tetracarboxylic acid dianhydride used in the present invention is not particularly limited, and may be either an aromatic tetracarboxylic acid dianhydride or an aliphatic tetracarboxylic acid dianhydride. Good. Specifically, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3, 5-tricarboxycyclopentyl acetic acid dianhydride, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,
4,5-Tetrahydrofuran tetracarboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5-tetrahydro- (2,5-dioxo-3-furanyl) -naphtho [1,2-c] -Fran-1,3-dione, 1,3,3
a, 4,5,9b-Hexahydro-5-methyl-5-tetrahydro- (2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 1,3 , 3
a, 4,5,9b-Hexahydro-8-methyl-5-tetrahydro- (2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione, 5- ( Two,
5-dioxotetrahydrofural) -3-methyl-3-
Cyclohexene-1,2-dicarboxylic 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) diphenyl sulfone 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 ( Examples thereof include aromatic tetracarboxylic dianhydrides such as (triphenylphthalic acid) -4,4′-diphenylmethane dianhydride, and aliphatic tetracarboxylic dianhydrides are particularly preferable. These may be used alone or in combination of two or more.

[Diamine Compound] The diamine compound is not particularly limited and may be either an aromatic diamine compound or an aliphatic diamine compound. Specifically, p-phenylenediamine, m-phenylenediamine, 4,4′-
Diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-
Dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminobenzanilide, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4'-diaminobiphenyl, 5- Amino-1- (4′-aminophenyl) -1,3,3-trimethylindane, 6-amino-1- (4′-aminophenyl)-
1,3,3-Trimethylindane, 3,4'-diaminodiphenyl ether, 3,3'-diaminobenzophenone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 2,2-bis [4- ( 4-Aminophenoxy) phenyl] propane, 2,2-bis [4-
(4-Aminophenoxy) phenyl] hexafluoropropane, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] sulfone, 1,4-bis (4-Aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9-bis (4-aminophenyl)
-10-hydroanthracene, 3,7-diaminofluorenone, 2,6-diaminofluorenone, 3,6-diaminofluorenone, 2,7-diaminofluorenone, 2,7
-Diaminofluorene, 9,9-bis (4-aminophenyl) fluorene, 4,4'-methylene-bis (2-chloroaniline), 2,2 ', 5,5'-tetrachloro-4,
4'-diaminobiphenyl, 2,2'-dichloro-4,
4'-diamino-5,5'-dimethoxybiphenyl, 3,
3'-dimethoxy-4,4'-diaminobiphenyl, 1,
4,4 '-(p-phenylene isopropylidene) bisaniline, 4,4'-(m-phenylene isopropylidene) bisaniline, 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, etc. Aromatic diamine compounds of

1,1-meta-xylylenediamine, 1,3-
Propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine,
1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine,
Hexahydro-4,7-methanoindanylene dimethylene diamine, tricyclo [6,2,1,0 ^2,7 ] -undecylenedimethyl diamine, 4,4'-methylene bis (cyclohexyl amine) and other aliphatic diamine compounds You can These may be used alone or in combination of two or more.

[Polyamic Acid] The polyamic acid used in the present invention is obtained by reacting a tetracarboxylic dianhydride and a diamine compound. Such a reaction is carried out in an organic solvent at a reaction temperature of usually 0 to 150 ° C, preferably 0 to 100 ° C. The usage ratio of the tetracarboxylic dianhydride and the diamine compound is the amino group 1 in the diamine compound.
The acid anhydride group of the tetracarboxylic dianhydride is preferably 0.2 to 2 equivalents, more preferably 0.2.
It is 3 to 1.2 equivalents. The organic solvent is not particularly limited as long as it can dissolve the polyamic acid generated in the reaction. For example, N-methyl-2-pyrrolidone, N,
Aprotic polar solvent such as N-dimethylacetamide, N, N-dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphortriamide; phenol such as m-cresol, xylenol, phenol and halogenated phenol. A system solvent can be mentioned. The amount of organic solvent used is
Usually, the total amount of tetracarboxylic dianhydride and diamine compound is 0.1 to 30% by weight based on the total amount of the reaction solution.
It is preferable that

The organic solvent includes alcohols, ketones, esters, which are poor solvents for polyamic acid,
Ethers, halogenated hydrocarbons, and hydrocarbons can be used together to the extent that the polyamic acid that is produced does not precipitate. Examples of the poor solvent include 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 polyamic acid may be a terminal modified type. By using this end-modified polyamic acid, the molecular weight can be adjusted, and the coating properties of the liquid crystal aligning agent can be improved without impairing the effects of the present invention. Such a terminal-modified type can be synthesized by attaching an acid monoanhydride or a monoamine compound to the reaction system when synthesizing the polyamic acid.

Here, examples of the acid monoanhydride include maleic anhydride, phthalic anhydride, and nadic acid anhydride, and examples of the monoamine compound include aniline, cyclohexylamine, n-butylamine, 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.

[Imidized Polymer] The imidized polymer of the polyamic acid used in the present invention is obtained by heating the polyamic acid or by dehydration ring closure in the presence of a dehydrating agent and an imidizing catalyst. . The imidized polymer is mainly a polyimide, but polyisoimide may be generated during dehydration ring closure, and the “imidized polymer” includes “polyimide” and “polyisoimide”. The reaction temperature for dehydration ring closure by heating is usually 60 to 250 ° C, preferably 100 to 170 ° C.
If the reaction temperature is less than 60 ° C, the reaction progresses slowly,
If the temperature exceeds 0 ° C, the molecular weight of the imidized polymer may be significantly reduced. The reaction in the case of dehydration ring closure in the presence of a dehydrating agent and an imidization catalyst can be carried out in the above-mentioned organic solvent. The reaction temperature is generally 0 to 180 ° C, preferably 60 to 150 ° C. As the dehydrating agent, acid anhydrides such as acetic anhydride, propionic anhydride, and trifluoroacetic anhydride can be used. Further, as the imidization catalyst, for example, tertiary amines such as pyridine, collidine, lutidine, and triethylamine can be used.
It is not limited to these. The amount of dehydrating agent used is
The amount is preferably 1.6 to 20 mol per 1 mol of the repeating unit of the corresponding polyamic acid. The amount of imidization catalyst used is 0.5 to 1 mol of the dehydrating agent used.
It is preferably 10 mol.

[Liquid Crystal Alignment Film] The liquid crystal alignment agent for forming the liquid crystal alignment film used in the present invention comprises the polyamic acid and / or the imidized polymer of the polyamic acid 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 synthesis reaction of polyamic acid and the dehydration ring closure reaction. In addition, the poor solvents exemplified as those which can be used together in the synthesis reaction of the polyamic acid can be appropriately selected and used in combination.

The concentration of the polyamic acid and / or the imidized polymer of the polyamic acid in the liquid crystal aligning agent is selected in consideration of viscosity, volatility, etc., but is preferably 1 to 10% by weight based on the whole solution. The range is.
That is, the liquid crystal aligning agent is applied to the surface of the substrate to form a coating film which becomes a liquid crystal aligning film. However, when the concentration is less than 1% by weight, the film thickness of this coating film becomes too small, which is good. If the liquid crystal alignment film cannot be obtained and 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 increases and the coating properties deteriorate.

The liquid crystal aligning agent may contain a functional silane-containing compound from the viewpoint of improving the adhesion of the polyamic acid and / or the imidized polymer of the polyamic acid to the substrate surface. Examples of such functional silane-containing compounds include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, 2-aminopropyltriethoxysilane, and N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N-
(2-Aminoethyl) -3-aminopropyltrimethyldimethoxysilane, 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-diaza Nonyl 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)-
Examples thereof include 3-aminopropyltriethoxysilane.

[Liquid Crystal Display Element] The liquid crystal display element of the present invention can be manufactured, for example, by the following method.

(1) First, a liquid crystal aligning agent is applied by a roll coater method directly or through an insulating film formed in advance to a display pixel formed of electrodes, for example, a substrate on which a comb-shaped transparent conductive film is provided. , Spinner method, printing method, etc., and heated at a temperature of 80 to 250 ° C., preferably 120 to 200 ° C. to form a coating film of polyimide and / or polyamic acid. The film thickness of this coating is usually 0.1.
001 to 1 μm, preferably 0.005 to 0.5 μm. As the substrate, for example, a transparent substrate made of glass such as float glass or soda glass, or a plastic film such as polyethylene terephthalate, polybutylene terephthalate, polyether sulfone or polycarbonate can be used. As the transparent conductive film, a NESA film made of SnO ₂ , In ₂ O ₃ —SnO ₂
It is possible to use an ITO film made of, for example, a photo-etching method for patterning these transparent conductive films.
A method using a mask in advance is used.

(2) Next, the entire surface of the coating film is irradiated with polarized ultraviolet rays, and if necessary, further 150 to 25
A heat treatment is performed at a temperature of 0 ° C. to impart liquid crystal aligning ability.
The ultraviolet rays used in the present invention are 150 to 450 n.
m having a wavelength of m, particularly 190 to 380 nm
Those having a wavelength of are preferred. The irradiation dose of ultraviolet rays is usually 1 to 10,000 mJ. As the light source of ultraviolet rays, for example, a low pressure mercury lamp, a high pressure mercury lamp, a deuterium lamp, a metal halide lamp, an argon resonance lamp, a xenon lamp, an excimer laser, etc. can be used.
The polarization of ultraviolet rays can be obtained by combining the light source with optical elements such as a polarizing plate and a polarizing prism.

(3) The two substrates on which the liquid crystal alignment film is formed on the display pixels are opposed to each other so that the polarized directions of the polarized ultraviolet rays irradiated on the liquid crystal alignment film are parallel to each other, and the peripheral portion between the substrates is arranged. Is sealed with a sealant, the liquid crystal is filled, the filling hole is sealed to form a liquid crystal cell, and polarizing plates are attached to both surfaces of the liquid crystal cell so as to be orthogonal or parallel to each other to form a liquid crystal display element. As the sealing agent, for example, an epoxy resin containing a hardening agent and aluminum oxide spheres as a spacer can be used. The liquid crystal is preferably a nematic liquid crystal, a smectic liquid crystal, and among them, a liquid crystal forming a nematic liquid crystal, for example, a Schiff base liquid crystal, an azoxy liquid crystal, a biphenyl liquid crystal, a phenylcyclohexane liquid crystal, an ester liquid crystal, a terphenyl liquid crystal. Liquid crystals, biphenylcyclohexane-based liquid crystals, pyrimidine-based liquid crystals, dioxane-based liquid crystals, bicyclooctane-based liquid crystals, cubane-based liquid crystals and the like are used. In addition to these liquid crystals, for example, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonaate and cholesteryl carbonate, and trade names C-15 and CB-
It is also possible to add a chiral agent such as that sold as No. 15 (Merck Ltd.). Furthermore, p-decyloxybenzylidene-p-amino-2-
Ferroelectric liquid crystals such as methylbutyl cinnamate can also be used. As a polarizing plate used outside the liquid crystal cell, while stretching and aligning polyvinyl alcohol,
Examples thereof include a polarizing plate in which a polarizing film called an H film absorbing iodine is sandwiched between cellulose acetate protective films, or a polarizing plate formed of the H film itself.

[0021]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

As for the visual characteristics, the optical characteristics at the time of driving the liquid crystal display device at 20 ° C. were measured by a liquid crystal panel evaluation device LCD-5000 manufactured by Otsuka Electronics. The pretilt angle of the liquid crystal alignment film was measured using the crystal rotation method. Further, the liquid crystal orientation of the liquid crystal display element was judged to be good when a voltage was applied to the liquid crystal cell and no abnormal domain was observed under a microscope.

Synthesis Example 1 22.42 g of 2,3,5-tricarboxycyclopentylcarboxylic acid dianhydride as tetracarboxylic acid dianhydride
(100.00 mmol), and 21.23 g (10) of 4,4'-diaminobenzophenone as a diamine compound.
0.00 mmol) of N-methyl-2-pyrrolidone 39
It was dissolved in 2.85 g and reacted at 60 ° C. for 6 hours. The reaction mixture was then poured into a large excess of methanol, causing the reaction product to precipitate. Then, it wash | cleaned with methanol and dried at 40 degreeC under reduced pressure for 15 hours, and obtained the polyamic acid A.

Synthesis Example 2 43.65 g of the polyamic acid A obtained in Synthesis Example 1 was added to 8
Dissolved in 29.35 g of N-methyl-2-pyrrolidone,
15.82 g of pyridine and 20.41 g of acetic anhydride were added, and dehydration ring closure was performed at 115 ° C. for 4 hours. Then, the reaction product solution was precipitated in the same manner as in Synthesis Example 1 to obtain polyimide A.

Synthesis Example 3 As tetracarboxylic dianhydride, 3,3 ', 4,4'-
Benzophenone tetracarboxylic dianhydride 32.23g
(100.00 mmol), and as diamine compound 4,4'-diaminodiphenylmethane 19.83 g (1
(0.000 mmol) N-methyl-2-pyrrolidone 4
It was dissolved in 68.54 g and reacted at 60 ° C. for 6 hours.
The reaction mixture was then poured into a large excess of methanol, causing the reaction product to precipitate. Then, it was washed with methanol and dried under reduced pressure at 40 ° C. for 15 hours to obtain polyamic acid B.

Example 1 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 the solution was filtered through a filter having a pore size of 1 μm to give a liquid crystal aligning agent solution. Prepared. This solution was applied to the transparent electrode surface of a glass substrate having a comb-shaped electrode with a transparent electrode made of an ITO film using a spinner so that the film thickness would be 800 Å, and dried at 220 ° C. for 1 hour to form a coating film. did. On the surface of the thin film, from the low pressure mercury lamp, the Glen laser prism G
Irradiation was performed by LP-0-1015-AN (manufactured by Sigma Koki Co., Ltd.) so that the polarization direction of the linearly polarized ultraviolet light was perpendicular to that of the comb electrodes. The irradiation amount of ultraviolet rays was 100 mJ. Next, the two substrates on which the liquid crystal alignment film is formed are stuck together with the liquid crystal alignment film surface inside so that the irradiated polarization directions are parallel to each other, and a liquid crystal ZLI-4792 manufactured by Merck & Co., Inc. is sealed, and a liquid crystal display device is provided. Was produced. The liquid crystal orientation of the produced liquid crystal display element was good, and the viewing angle was measured to be 140 °.
Met. Further, the pretilt angle was not developed by this ultraviolet polarized light irradiation treatment.

Example 2 Except that the polyamic acid B obtained in Synthesis Example 3 was used,
When a liquid crystal display element was produced in the same manner as in Example 1, the liquid crystal had good orientation and a viewing angle of 140 °. Further, when the pretilt angle was measured, the pretilt angle did not appear.

Comparative Example 1 Using the polyimide A obtained in Synthesis Example 2, a liquid crystal aligning agent was prepared in the same manner as in Example 1, coated on the substrate used in Example 1, and dried at 220 ° C. for 1 hour. To form a coating film.
Using a rubbing machine having a roll in which a nylon cloth is wrapped around this coating film, the roll indentation length is 0.6
The rubbing treatment was performed at a roll speed of 500 mm, a roll rotation speed of 500 rpm, and a stage moving speed of 1 cm / sec. Next, the two substrates on which the liquid crystal alignment film is formed are laminated so that the rubbing directions are anti-parallel with the liquid crystal alignment film surface inside, and a liquid crystal ZLI-4792 manufactured by Merck Ltd. is enclosed to form a liquid crystal display device. It was made. The liquid crystal alignment of the produced liquid crystal display element was good, but the viewing angle was 100 ° when measured. The pretilt angle developed by this rubbing treatment was 1.2 °.

Comparative Example 2 Except that the polyamic acid B obtained in Synthesis Example 3 was used,
When a liquid crystal display device was produced in the same manner as in Comparative Example 1, the liquid crystal had good orientation, but the viewing angle was 105 °. Moreover, when the pretilt angle was measured, the pretilt angle was 1.3 °.

[0030]

According to the present invention, it is possible to obtain a horizontal electric field type liquid crystal display device having excellent visual characteristics, particularly a wide viewing angle. Further, since the adhesion of dust and the destruction of the TFT element due to static electricity generated during the conventional rubbing treatment do not occur, the alignment film can be manufactured with a high yield.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuo Matsuki 2-11-24 Tsukiji, Chuo-ku, Tokyo Inside Nippon Gosei Rubber Co., Ltd.

Claims (1)

[Claims] 1. A liquid crystal alignment film holding substrate composed of a substrate and a display pixel formed on the substrate by electrodes and a liquid crystal alignment film formed directly on the display pixel or through an insulating film, and A liquid crystal display element in which a liquid crystal layer is sandwiched between two alignment film holding substrates, the electrodes being configured to generate an electric field substantially parallel to the substrates. Further, the alignment film is formed by irradiating a coating film of polyimide and / or polyamic acid with polarized ultraviolet light, and the pretilt angle of the alignment film is 0 ° to 0 °.
A liquid crystal display device characterized by being 0.1 °.