JPS63243918A - Formation of liquid crystal orientation film - Google Patents

Abstract

PURPOSE:To obtain the titled film having excellent heat resistance and mechanical properties by forming a coated film obtd. by applying a polyamidic acid contg. a repeatedly structural unit having a prescribed composition, on a substrate forming a liquid crystal element, followed by treating the obtd. coated film with a silane compd. and/or a monoamine having a prescribed composition. CONSTITUTION:The liquid crystal orientation film is formed by applying the polyamidic acid contg. the repeatedly structural unit shown by formula I, on the substrate forming the liquid crystal display element, and then, treating the obtd. coated film with the silane compd. and/or the monoamine shown by formula II. In formula I, R<0> is a four valent aliphatic or alicyclic ring group, R<1> is a bivalent org. group. And, in formula II, R<2> is a monovalent org. group, X is alkyl, acyloxy, aryloxy group or halogen atom, Y is hydrogen atom, alkyl, aryl, alkoxy, acyloxy or aryloxy group.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for forming a liquid crystal alignment film, and more specifically, after coating a polyamic acid to form a coating film, the coating film is further treated in a specific manner. The present invention relates to a method for forming a liquid crystal alignment film that is treated with a silane compound and/or a monoamine.

[Conventional technology]

Conventionally, a nematic liquid crystal with positive dielectric anisotropy is sandwiched between transparent electrodes coated with a liquid crystal alignment film, and the long axis of the liquid crystal molecules is twisted continuously by 90 degrees between the upper and lower substrates.
A display element having N array cells (TN type display element) is known.

This alignment of liquid crystals can be achieved by rubbing a liquid crystal alignment film made of polyimide or the like coated on a transparent electrode in one direction with a roll wrapped with synthetic fiber cloth, and then rubbing the alignment films on the upper and lower substrates. This can be achieved by incorporating them so that their directions are perpendicular to each other.

However, this TN type display element has problems with contrast and viewing angle dependence, and recently S B E (Su
per twsited Birefrency
Effect) display elements have become known. This display element uses a nematic liquid crystal blended with an optically active substance as the liquid crystal, and utilizes the birefringence effect produced by continuously twisting the long axis of the liquid crystal molecules by 180 degrees or more between the upper and lower substrates. It is.

Conventionally, this display element uses SiO to orient the liquid crystal.
However, this method has problems in terms of display reproducibility and manufacturing cost.

Furthermore, when an SBE display element is manufactured using polyimide as described above as a liquid crystal alignment film, the pretilt angle between the long axis of the aligned liquid crystal molecules and the liquid crystal alignment film becomes small, so that it is difficult to twist the liquid crystal by more than 180 degrees. It has problems in that the contrast is poor, the viewing angle dependency is large, and the display function is not fully expressed compared to the TN type display element.

[Problem that the invention seeks to solve]

An object of the present invention was to solve the above-mentioned conventional technical problems, and to provide a liquid crystal display element having excellent heat resistance, mechanical properties, electrical properties, chemical resistance, and adhesive properties and a large pretilt angle, particularly SBE. The present invention provides a method for forming a liquid crystal alignment film for display elements.

[Means for solving problems]

In the present invention, a polyamic acid having a repeating structural unit represented by the following general formula (I) is coated on a substrate forming a liquid crystal display element to form a coating film, and then the coating film is coated with the following general formula (I). The present invention provides a method for forming a liquid crystal aligning film, which is characterized in that it is treated with a silane compound represented by It) and/or a monoamine.

(In the formula, Ro represents a tetravalent aliphatic group or alicyclic group, and R1 represents a divalent organic group.)
(In the formula, R2 is a monovalent organic group, X is an alkyl group, an acyloxy group, an aryloxy group, or a halogen atom, and Y is a hydrogen atom, an alkyl group, an aryl group, an alkoxy group, an acyloxy group, or an aryoxy group. ) RO in the general formula (1) is, for example, butanetetracarboxylic acid, 1,2,3,4-cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopenkunetetracarboxylic acid, 2,3 .5-tricarboxycyclopentyl acetic acid, 3,5,6-tricarboxynorbornane-2-acetic acid, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-cyclohexenedicarboxylic acid, bicyclo(2,2, , 2)-octo-7-nin-tetracarboxylic acid, etc., with four carboxyl groups removed, such as a tetravalent aliphatic group or alicyclic group.

R1 in the general formula (1) is, for example, (wherein, XI, Xt, X3 and X4 may be the same or different, -Hl-CH3 or -CHs
, Yo is −CHt −, −Cz
a divalent aromatic group represented by Ha -, -0-1-S-1-C-2 -CONH-, where n is 0 or 1), -(CHt)n'- (in the formula, n' represents an integer of 2 to 20; and R# is C1,"Hz,,"-+ (where n# is 1 to 20
represents a monovalent aliphatic, alicyclic or aromatic hydrocarbon group such as
Examples include divalent organic groups such as organosiloxane groups represented by:

The polyamic acid represented by the general formula (I) used in the present invention can be obtained, for example, by reacting an aliphatic or alicyclic tetracarboxylic dianhydride with a diamine.

The aliphatic or alicyclic tetracarboxylic dianhydride used in the present invention includes, for example, butanetetracarboxylic dianhydride, 1,2,3°4-cyclobutanetetracarboxylic dianhydride, 1° 2.3.4-Cyclopentanetetracarboxylic dianhydride, 2.3.5-tricarboxycyclopentyl acetic dianhydride, 3.5.6-) Licarboxynorbornane-2-acetic dianhydride, 5-
(2゜5-dioxotetrahydrofuryl)-3-methyl-cyclohexenedicarboxylic anhydride, bicyclo(2
, 2,23-octo-7-nin-tetracarboxylic dianhydride, etc., and tetracarboxylic acid can also be used in combination with these.

Further, these aliphatic or alicyclic tetracarboxylic dianhydrides can be used in combination with other tetracarboxylic dianhydrides.

Here, examples of other tetracarboxylic dianhydrides include pyromellitic dianhydride and 3.3'.

4.4'-benzophenonetetracarboxylic dianhydride-
, 3,3', 4.4'-biphenylsulfonetetracarboxylic dianhydride, 1,4,5.8-naphthalenetetracarboxylic dianhydride, 2,3,6°7-naphthalenetetracarboxylic dianhydride 3゜3', 4.4'-Biphenyl ether tetracarboxylic 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)diphenylsulfide anhydride; 4.
4'-bis(3,4-dicarboxyphenoxy)diphenylsulfone dianhydride, 4.4'-bis(3,4-dicarboxyphenoxy)diphenylpropanihydride, 3
．． 3', 4゜4'-perfluoroisopropylidene tetracarboxylic dianhydride, 3.3', 4.4'-biphenyl ether tetracarboxylic dianhydride, bis(phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis-(triphenylphthalic acid) di=hydrate,
m-phenylene-bis-(triphenylphthalic acid) dianhydride, bis(triphenylphthalic acid)-4,4'-
Diphenyl ether dianhydride, bis(triphenylphthalic acid).

Aromatic tetracarboxylic dianhydrides such as -4,4'-diphenylmethane dianhydride can be mentioned, and these can also be used in combination.

The mixture v1 of these tetracarboxylic dianhydrides is about 0.2 to 0.95 mol based on 1 mol of the total amount of the aliphatic and alicyclic tetracarboxylic dianhydrides.

Further, as the diamine to be reacted with the tetracarboxylic dianhydride, a compound represented by the general formula; HzPfi R' NH2 (R'
are the same as above).

Specific examples of the diamine include 1, para-phenylene diamine, meta-phenylene diamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, benzidine, 4,4'-diaminodiphenyl sulfide, 4,4'- Diaminodiphenylsulfone, 4.4'
-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'-diaminobenzophenone, 2,2-bis(4-
(4-aminophenoxy)phenyl]propane, bis(
4-(4-aminophenoxy)phenyl]sulfone,
1.4-bis(4-aminophenoxy)benzene, l,
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)
Aromatic diamines such as -5,5'-dimethoxybiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, metaxylylene diamine, l,3-propanediamine, tetramethylene diamine, pentamethylene diamine, hexa Methylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, 4
．． 4'-dimethylhebutamethylene diamine, 1,4-diaminocyclohexane, isophorone diamine, tetrahydrodicyclopentadienyl diamine, hexahydro-4,7-methanoindanilene shimethylene diamine, tricyclo(6,2,1,0 Examples include aliphatic or alicyclic diamines such as ".7]-randecylendimethyldiamine, and diaminoorganosiloxanes represented by the following formulas, and these diamines can also be used in combination.

The polyamic acid of the present invention can be obtained by reacting the tetracarboxylic dianhydride and diamine in a solvent by a conventionally known method.

The organic solvent that can be used for producing the polyamic acid is not particularly limited as long as it can dissolve the polyamic acid, such as N-methyl-2-pyrrolidone,
Aprotic polar solvents such as N,N-dimethylacetamide, N,N-dimethylformamide, dimethylsulfoxide, γ-butyrolactone, tetramethylurea, hexamethylphosphorotriamide, m-cresol, xylenol, phenol, halogenated phenol, etc. Examples include phenolic solvents, and these organic solvents can also be used in combination.

The reaction temperature when synthesizing polyamic acid is usually 0 to 1
The reaction may be carried out at 00°C.

The polyamic acid used in the present invention may be partially dehydrated and ring-closed and imidized in the synthesis step, or may be partially imidized chemically or thermally after synthesis.

Furthermore, the intrinsic viscosity [η
5nh=ln(ηraL/C), C”0.5g/
d1.30℃, in dimethylformamide] is usually 0
．． 05-10dl/g, preferably 0.05-5dl/
It is g.

Preferred examples of the polyamic acid used in the present invention are 2,
It is a polyamic acid having a repeating structural unit represented by the following general formula (I[[) or (IV)] obtained using 3.5-tricarboxycyclopentyl acetic dianhydride and a diamine, (wherein R' is the same as above.) In particular, polyamic acids containing repeating structural units represented by the general formula (II) or (IV), preferably 50% by weight or more, particularly preferably 75% by weight or more, are suitable. .

The polyamic acid used in the present invention is easily soluble in a solvent and is very stable even in a solution state, and does not become cloudy or change in viscosity even after long-term storage.

In the present invention, this polyamic acid is usually first applied as a solution to the substrate of a liquid crystal display element.

The solvent used when preparing this polyamic acid solution is preferably a solvent that dissolves the polyamic acid, and other general organic solvents such as alcohols, phenols, ketones, esters, lactones, ethers, Halogenated hydrocarbons, hydrocarbons such as methyl alcohol, ethyl alcohol, i-propyl 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 chelate, diethyl malonate, diethyl ether, ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol-n-
Propyl ether, ethylene glycol-1-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, 0-dichlorobenzene, hexane, heptane, octane, benzene, toluene , xylene, etc. can be mixed to an extent that the polyamic acid is not precipitated.

In the present invention, when preparing a polyamide acid solution, polyamide is usually dissolved in a solvent and the solid content concentration is 0.
A solution of 1 to 30% by weight, preferably 0.5 to 20% by weight is prepared.

The polyamic acid solution prepared in this way is applied to a substrate by a roll coater method, a spinner method, a printing method, etc., and then heated to a temperature of 80 to 400°C, preferably 100 to
A coating film of polyamic acid can be formed by heating and drying at 50° C. for 5 to 180 minutes, preferably 10 to 120 minutes.

The thickness of this polyamic acid coating is usually 0.01=1
．． crm, preferably 0.01-0.5 μm.

In addition, if necessary, in order to further improve the adhesion with the substrate, a silane coupling agent,
It is also possible to apply a titanium coupling agent or the like to improve the adhesion between the substrate and polyamic acid.

In the present invention, after a coating film of polyamic acid is first formed on a substrate in this manner, it is further treated with a silane compound represented by the general formula (II) and/or a monoamine.

R2 in the general formula (II) is a monovalent organic group, such as 2-cyanoethyl group, 3-cyanopropyl group, 2-cyanopropyl group,
Organic groups having a cyano group such as cyanopropyl group, 2-cyanobutyl group, 3-cyanobutyl group, 4-cyanobutyl group, cyanomethylphenethyl group, methyl group, ethyl group, propyl group, n-butyl group, i-butyl group , alkyl groups such as n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-dodecyl group, amino such as 2-aminoethyl group, 3-aminopropyl group, 4-aminobutyl group, etc. organic group having a group, 2-ureidoethyl group,
List organic groups having a ureido group such as 3-ureidopropyl group and 4-ureidobutyl group, and organic groups having halogen atoms such as fluorine atom, chlorine atom, and bromine atom such as methyl group, ethyl group, and propyl group. Can be done.

Further, as X in the general formula (II), for example, a methyl group, an ethyl group, an n-propyl group, an n-butyl group,
Alkyl groups having 1 to 5 carbon atoms such as n-pentyl group, acyloxy groups such as acetoxy group, propanoyloxy group, butanoyloxy group, phenoxy group, methylphenoxy group,
Examples include acyloxy groups such as a dimethylphenoxy group and a nutracenoxy group, and halogen atoms such as a fluorine atom, a chlorine atom, and a bromine atom.

Further, as Y in the general formula (II), for example, a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, an n-
- Alkyl groups having 1 to 5 carbon atoms such as butyl group and n-pentyl group, aryol groups such as phenyl group, tolyl group and xylyl group, methoxy group, ethoxy group, n-propoxy group,
1 to 5 carbon atoms such as n-butoxy group and n-pentoxy group
alkoxy group, acetoxy group, propanoyloxy group,
Examples include acyloxy groups such as a butanoyloxy group, aryloxy groups such as a phenoxy group, a methylphenoxy group, a dimethyphenoxy group, and a natutarenoxy group.

Specific examples of the silane compound represented by the general formula (II) include 2-cyanoethyltriethoxysilane, 3-cyanopropyltriethoxysilane, 3-cyanopropyldimethylmethoxysilane, 2-cyanoethyltrichlorosilane, and 2-cyanoethyltriethoxysilane. Ethylmethyldichlorosilane, 3-
Cyano group-containing silane compounds such as cyanobutylmethyldichlorosilane and cyanomethylphenethyltriethoxysilane; propyltriethoxysilane, octyltriethoxysilane, dodecylmethyljethoxysilane, dodecyltriethoxysilane, octylmethyldichlorosilane, octyltrichlorosilane, Alkylsilane compounds such as octylmethyldimethoxysilane, octylphenoxydiacetoxysilane, dodecylmethyljethoxysilane; 3-aminopropyltriethoxysilane, 2-aminopropyltrimethoxysilane, N7(2-aminoethyl)-3-propyl Methyldimethoxysilane, N-ethoxycarbonyl-3-amino-propyltrimethoxysilane, N-methyl-3-aminopropyltrimethoxysilane, N,N-dimethyl-3-aminopropyltriethoxysilane, 4-aminophenethyltriethoxy Silane compounds containing amino groups such as silane and 3-aminobutyltriethoxysilane; 3-ureido-propyltriethoxysilane, 3-ureido-butyltriethoxysilane, 3-ureido-propyltrimethoxysilane, 3-ureidobutyl Ureido group-containing silane compounds such as trimethoxysilane, 3-ureido-propyltrichlorosilane, 3-ureido-butyltrichlorosilane, 4-ureidophenethyltriethoxysilane; 3.3.3-
Trifluoropropyltrimethoxysilane, 3,3.3
-trifluoropropylmethyldimethoxysilane, heptadecafluoro-1,1,2,2-tetrahydrodecyltriethoxysilane, heptadecafluoro-1,1,2
, 2-tetrahydrodecyltriethoxysilane, tridecafluoro-1,1,2゜2-tetrahydrooctyltriethoxysilane, 3-trifluoroacetoxypropylenetrimethoxysilane, 1,1.2.2-tetrafluoroethyltrichlorosilane , 3,3.3-trifluoropropyldimethylchlorosilane 77.3,3.3-trifluoropropylmethyldichlorosilane, 3°3.3-
Examples include fluorine-containing silane compounds such as trifluoropropyldichlorosilane, and among these, cyano group-containing silane compounds or fluorine-containing silane compounds are preferred.

These silane compounds can also be used in combination.

Next, examples of the monoamine include hexylamine, octylamine, decylamine, dodecylamine, butylamine, pentylamine, dibutylamine, dipentylamine, dioctylamine, dioctylamine, methylhexylamine, ethyloctylamine, dimethyldodecylamine, etc. Alkylamines; Aromatic amines such as aniline, phenylethylamine, phenylpropylamine, diphenylamine, 2,4-dimethylphenylamine, α-naphthylmethylamine, α-naphthylethylamine; iminodipropionitrile, p-cyanoaniline, 2-cyanoethyl Amine, 3-cyanopropylamine, 4-cyanocyclohexylamine, p-cyanoaniline, p-cyanophenylmethylamine, di(p-
Examples include cyano group-containing amines such as cyanophenyl) amines, and among these, alkyl amines or cyano group-containing amines are preferred.

These monoamines can also be used in combination.

Moreover, the silane compound represented by general formula (II) and a monoamine can also be used together.

The above-mentioned silane compound and/or monoamine are applied as they are or dissolved in a suitable solvent onto a coating film made of polyamic acid.

When adding an organic solvent to the silane compound and/or monoamine used in the present invention and using it as a solution,
A substance that does not dissolve or significantly swell the coating film made of the polyamic acid, and which does not contain these silane compounds and/or
Alternatively, it is not particularly limited as long as it does not react rapidly with monoamines.

Specific examples of this organic solvent include benzene, toluene,
Aromatic hydrocarbons such as xylene, ethylbenzene, propylbenzene, diethylbenzene; halogenated hydrocarbons such as methylene chloride, chloroform, benzene chloride, benzene bromide; methanol1. Alcohols such as ethanol, propatool, cyclohexanol, methyl cellosolve, ethyl cellosolve, butyl cellosolve, carpitol, cyclohexanol; ethers such as tetrahydrofuran, dioxane, diglyme, carpitol ethyl ether; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexane.

Ketones such as Sanone, methylcyclohexylketone;
Examples include esters such as ethyl acetate, butyl cellosolve acetate, carpitol acetate, butyl carbitol, and -ruacetate, among which aromatic hydrocarbons or halogenated hydrocarbons are preferred.

When using this silane compound and/or monoamine as an organic solvent solution, the solid content concentration is usually 0.1.
~20% by weight, preferably 0. It is adjusted to 5-10% by weight.

The silane compound and/or monoamine is applied onto the coating film of polyamic acid present on the substrate using a roll coater method,
It is applied by a spinner method, a printing method, a dipping method, etc., and then at a temperature of, for example, 80 to 400°C, preferably 100 to 350°C.
Dry for 5 to 180 minutes, preferably 10 to 120 minutes.

The thickness of the coating film after treatment with the silane compound and/or monoamine is usually 0.01 to 1 μm, preferably 0.01 to 0.5 μm.

After drying, a normal rubbing treatment is performed to form a liquid crystal alignment film.

A liquid crystal display element using a liquid crystal alignment film formed according to the present invention can be manufactured, for example, by the following method.

First, the polyamic acid solution is applied to an area other than the electrode wiring part of a substrate having a transparent electrode by the method described above, heated and dried to form a coating film of polyamic acid, and the silane compound and/or monoamine is applied to the polyamic acid solution. A liquid crystal aligning film is formed by coating on the coating film, heating and drying.

The thus obtained liquid crystal alignment film is rubbed with a roll wrapped with a synthetic fiber cloth such as nylon to perform liquid crystal alignment treatment.

Next, the periphery of the substrate treated as described above and the substrate on the counter electrode electrode side having a liquid crystal alignment film on the substrate are sealed with a sealant so as to leave a gap, and liquid crystal is filled between the two substrates. Then, the sealing port is sealed with a sealant to form a liquid crystal display cell.
By pressing orthogonal polarizing plates to both surfaces, a liquid crystal display element is obtained.

Here, substrates used for liquid crystal display elements include float glass, soda glass, flexible polyester films such as polyethylene terephthalate and polybutylene terephthalate, as well as polyether sulfone, polycarbonate, and other plastic films. A transparent substrate can be used.

The transparent electrode (electrode) is NESA made of SnO.
An ITO film consisting of In, 0s-3nO, and the like can be used for patterning these electrodes.
An etching method or a method using a mask in advance is used.

As the sealant, for example, an epoxy resin composition containing a filler, a hardening agent, and aluminum oxide spheres as spacers can be used.

Examples of liquid crystals used in liquid crystal display elements include Schiff base liquid crystals, azoxy liquid crystals, biphenyl liquid crystals, phenylcyclohexane liquid crystals, ester liquid crystals, terphenyl liquid crystals, biphenylcyclohexane liquid crystals,
Examples include nematic liquid crystals such as pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, and cupane liquid crystals. Furthermore, in addition to these liquid crystals, cholesteric liquid crystals such as cholesteryl chloride, cholesteryl nonaate, and cholesteryl carbonate, and the product name C-
It is also possible to add chiral nematic liquid crystal such as CB-15 (manufactured by British Druckhaus, UK). Also, D
OBAMBC (Dodecyl Oxy Benzyl
idene Aa+ino Methyl Butyl
Ferroelectric liquid crystals such as Cinnamate) can also be used.

The polarizing plate used on the outside of the substrate (outside of the liquid crystal cell) is a polarizing plate made of cellulose acetate protective film or H film sandwiching a polarizing film called H film, which is made by stretching and aligning polyvinyl alcohol and absorbing iodine. Examples include a polarizing plate made of the same.

〔Example〕

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1-9 4.4'-diaminodiphenyl ether (D D E)
After dissolving 18.00 g (0,0899 mol) in 343 g of N-methylpyrrolidone (NMP), 2.3
．． 5-) Lycarboxycyclopentyl acetic dianhydride (T
CA-AH) 20.15 g (0,0899 mol) was added as a powder and reacted for 3 hours at room temperature with stirring to obtain a polyamic acid solution with a polymer concentration of 10% by weight (polyamic acid A).

ηi of the obtained polyamic acid A, 1k (0.5g/
8230°C, in dimethylformamide) is 0.9 dl
/g. The 10% by weight polyamic acid solution thus obtained was filtered through a membrane filter with a pore size of 0.22 μm to remove insoluble matter.

This polyamic acid solution was applied onto the transparent electrode surface of a glass substrate with a transparent electrode made of ITO using a spinner at a rotation speed of 5. It was applied at OOOrpm and dried at 180°C for 1 hour. The thickness of the coating film at this time was 0.12 μm.

Next, the substrate having the dried polyamic acid coating film was immersed in a solution containing 2% by weight of various treatment agents (silane compounds or monoamines) shown in Table 1, and then heated and dried at a predetermined temperature. The heat-treated coating film on the dried substrate was rubbed using a rubbing machine having a roll wrapped with a nylon cloth at a roll rotation speed of 5 QQ rpm and a stage movement speed of 1 c+a/sec.

Next, an adhesive containing a spacer (manufactured by Mitsui Toatsu Kagaku ■, Structbond XN-5A) having a diameter of 17 μm was screen printed on the substrate, and then the upper and lower substrates were pressed together so that the rubbing directions were antiparallel.

Next, we introduced the nematic liquid crystal ZLI-2293 (USA,
After injecting the solution (manufactured by Merck & Co., Ltd.), the injection port was sealed to produce a liquid crystal display cell.

The fabricated liquid crystal display cell is described in the literature (T, J, 5che
ffer.

et al., J. Appl., Phys.
48.1783 (1977), F. Nakano,
et al, + JPN* J, Appl, Ph
ys, +19.

The pretilt angle was measured by a crystal rotation method using laser light (He-Ne) according to the method described in 2013 (1980). The results are shown in Table 1.

Example 10-1) Paraphenylenediamine 2.16g (20 mmol)
, 3.93 g (18 mmol) of pyromellitic anhydride and 58.8 g of NMP were reacted in the same manner as in Example 1 to obtain a polyamic acid solution (polyamic acid B).

'74. of the obtained polyamic acid B. lk (0,5g
/dj130℃, in dimethylformamide)
It's 0.9d17g.

The polyamic acid solution obtained in this way was used in Example 1.
The mixture was filtered in the same manner as above to remove insoluble matter.

Using this solution, a liquid crystal display cell was produced in the same manner as in Example 1, and the pretilt angle was measured.

The results are shown in Table 1.

Comparative Examples 1 to 2 In Example 1 or Example 1O, a liquid crystal display cell was prepared in the same manner as in Example 1 or Example 10, except that the coating film of polyamic acid was not treated with a silane compound or a monoamine, and the pretilt angle was measured. did. The results are shown in Table 1.

(Leaving space below) Example 12 The polyamic acid solution obtained in Example 5 was applied onto the transparent electrode surface of a glass substrate with a transparent electrode made of ITO using a spinner at a rotation speed of 5.00 rpm, and then heated at 180°C. It was dried for 1 hour to form a coating film with a thickness of 0.12 μm.

The substrate with the dried polyamic acid coating was then operated in the same manner as in Example 5 using the same silane compound as in Example 5.

Next, an adhesive containing a spacer (manufactured by Mitsui Toatsu Kagaku ■, Structbond XN-5A) having a diameter of 10 μm was screen printed on the substrate, and then the upper and lower substrates were pressed together so that the rubbing directions were perpendicular to each other.

Next, a liquid crystal consisting of a mixture of nematic liquid crystal ZLI-2293 (manufactured by Merck & Co., USA) and chiral agent CB-15 (manufactured by British Drug House, UK) was injected, and the injection port was sealed. An SBE liquid crystal display element was manufactured by pressing orthogonal polarizing plates onto both sides of a liquid crystal display cell.

When this viewing angle dependence was investigated, it was clearly visible from +60° to -60″ with respect to the direction orthogonal to the substrate surface.

Comparative Example 3 A liquid crystal display element was produced in the same manner as in Example 12, except that the polyamic acid coating was not treated with a silane compound.

This liquid crystal display element has a dislocation in the alignment of the liquid crystal, and the SB
As an E-liquid crystal display element, its display function was insufficient.

〔Effect of the invention〕

The liquid crystal alignment film obtained by the present invention has excellent heat resistance, mechanical properties, electrical properties, chemical resistance, and adhesion to substrates, and is particularly suitable as a liquid crystal alignment film for liquid crystal display elements with a large pretilt angle. Useful.

The liquid crystal alignment film obtained by the present invention can be used for any display such as SBE display, TN type display, or ferroelectric liquid crystal display by selecting the liquid crystal used, but it is particularly suitable for SBE display. can be used.

In particular, the liquid crystal display element using the liquid crystal alignment film obtained by the present invention has excellent alignment properties and high reliability, and can be used in combination with a polarizer such as a linear polarizing plate or a circular polarizing plate, or a reflecting plate. It can be effectively used in various devices, such as electronic desktop calculators, wristwatches, table clocks, coefficient display boards, word processors, personal computers, and display devices for liquid crystal televisions.

Claims (1)

[Claims] (1) On the substrate forming the liquid crystal display element, apply the following general formula (
It is characterized by coating a polyamic acid having a repeating structural unit represented by I) to form a coating film, and then treating the coating film with a silane compound and/or monoamine represented by the following general formula (II). A method for forming a liquid crystal alignment film. ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(I) (In the formula, R^0 is a tetravalent aliphatic group or alicyclic group, R^
1 represents a divalent organic group. ) R^2-SiX_2Y...(II) (In the formula, R^2 is a monovalent organic group, X is an alkyl group, acyloxy group, aryloxy group, or halogen atom, Y is a hydrogen atom, an alkyl group, (Indicates an aryl group, alkoxy group, acyloxy group, or aryloxy group.)