JPS62291623A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To obtain an element which is free from the disturbance of orientability by consisting an oriented film of a heat-treated film consisting of a specific polyamide acid, tertiary amine compd. and specific silanol compd. and/or the partial condensation product thereof. CONSTITUTION:The oriented film consists of the heat-treated film of the polyamide acid having the structural unit expressed by the formula I, the tertiary amine compd. and the signal compd. expressed by the formula II and/or the partial condensation product thereof. In the formula, R1 is a trivalent or tetravelent org. group, R2 is a bivalent org. group, m is 1 or 2, R3 is a monovalent org. group, n is 1-3. The tertiary amine of the compd. consisting of the polyamide acid and silanol compd. expressed by the formulas I and II and the tertiary amine compd. has the effect of improving the transparency of the film, the effect of accelerating imide ring closure and the effect of accelerating the condensation of the silanol compd. The satisfactory film performance is thus obtd. by the interaction thereof even if the film is subjected to the heat treatment at a low temp.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a liquid crystal display element, and more particularly to a liquid crystal display element using a specific alignment control film.

[Prior Art] Conventionally, liquid crystal display elements, particularly nematic liquid crystal display elements that operate under the action of an electric field and utilize the electro-optic effect, have been made using amorphous materials such as vapor-deposited films of silicon oxide, organic polymers such as polyimide, etc. Molecular materials were known as alignment control films.

Although inorganic materials have advantages such as having no factors that adversely affect liquid crystals when in contact with liquid crystals and having good heat resistance, they have the disadvantage of high manufacturing costs.

For this reason, organic polymer materials with excellent ω productivity and therefore low manufacturing costs are currently the mainstream.

Among organic polymer materials, polyimide can be cited as a material that forms an alignment film with relatively excellent alignment properties. For example, it is obtained by coating polyamic acid, which is a polyimide precursor obtained by condensation of pyromellitic dianhydride and 4°4°-diaminodiphenyl ether as described in JP-A No. 51-65960, and then ring-closing it by heating. Polyimide has good properties in terms of uniformity of orientation and durability in deterioration tests. However, many polyimides, typified by polyimides obtained from pyromellitic dianhydride and diaminodiphenyl ether, are 300'C-
This method requires an imide ring-closing temperature of 350'C, and there is a problem in that the substrate (glass) is damaged due to thermal strain during this heat treatment process.

In addition, to prevent damage to the substrate, the imide ring-closing temperature was set to 2.
When lowered to 50'C, the deterioration test (70°C, 95% R81
After 100 hours), the orientation was disturbed and there was a problem that characters were blurred.

[Problems to be Solved by the Invention] It is an object of the present invention to solve the above-mentioned problems and provide a liquid crystal display element in which imide ring closure can be performed at low temperatures and alignment is not disturbed in a deterioration test.

[Means for Solving the Problems] The present invention provides (1) a liquid crystal display element having a liquid crystal alignment film on a substrate on which transparent electrodes are formed, in which the alignment film has the following formula: In the middle, R1 is a trivalent or tetravalent organic group, and R2 is 2
The valent organic group, m, is 1 or 2. ), B, a tertiary amine compound and C9 general formula % formula % [ (wherein (R3) is a monovalent organic group, n is 1, 2
, 3. ) A liquid crystal display element comprising a heat-treated film of a silanol compound [n] and/or a partial condensate thereof.

In the present invention, the polyamic acid having the structural unit [, -I] refers to a polymer having the structure represented by the above general formula and having an imide ring or other cyclic structure by heating or using a suitable catalyst (Ishitoshi, Polyimide 1q).

In the above structural unit [I], R is a trivalent or tetravalent organic group having at least two or more carbon atoms. From the viewpoint of heat resistance of the polyimide polymer, R1 preferably has a structure in which the bond to the carbonyl group of the polymer main chain is directly formed from an aromatic ring or an aromatic heterocycle. Therefore,
R1 is preferably a trivalent or tetravalent group containing an aromatic ring or an aromatic heterocycle and having 6 to 30 carbon atoms.

More preferable specific examples of R1 include -o-, -o
-o-o-, -o-sO=-o-.

(In the formula, the bond represents a bond with the carbonyl group of the polymer main chain, and the carboxyl group is located at the ortho position to the bond, but this bond is not described in the above @structure).

Examples include, but are not limited to, the following.

Further, in the polymer having the structural unit [I], R1 may be composed of only one type of these, or may be a copolymer composed of two or more types.

Particularly desirable R1 is (however, in the formula, the definition of the bond is the same as above).

In the @ structural unit [I] above, R2 is a divalent carrier group having at least two or more carbon atoms, but from the viewpoint of heat resistance when used as a polyimide polymer, it is difficult to combine it with the amide group of the polymer main chain. It is preferable to have a structure in which the bonding is carried out directly from an aromatic ring or an aromatic heterocycle. Therefore, R2 contains an aromatic ring or an aromatic heterocycle and has 6 carbon atoms.
-30 divalent groups are preferred.

Preferred specific examples of R2 include (in the formula, the bond represents a bond with the amide group of the main chain). Furthermore, these may have substituents such as amine groups, amide groups, carboxyl groups, and sulfonamide groups within the range that does not adversely affect the heat resistance of the polyimide polymer. Particularly preferred examples of those having each of these substituents are listed below.

In the polymer having the structural unit [1], R2 may be composed of only one type of these, or may be a copolymer composed of two or more types.

Furthermore, in order to improve the adhesiveness of the polyimide polymer, it is also possible to copolymerize an aliphatic group having a siloxane structure as R2 within a range that does not reduce the heat resistance. Preferred specific examples are listed.

Specific examples of polymers containing the structural unit [I] as main components include pyromellitic dianhydride and 4,4-diaminodiphenyl ether, pyromellitic dianhydride and 3.3' /l,
4"-Benzophenonetetracarboxylic acid and 4,4-diaminodiphenyl ether, 3.3°, 4,4-benzophenonetetracarboxylic dianhydride and 4,4-diaminodiphenyl ether, 3.3
”, 4,4-biphenyltetracarboxylic dianhydride and 4
, 4°-diaminodiphenyl ether, 3.3°, 4,
4-biphenyltetracarboxylic dianhydride and 3.3
', 4,4-benzophenonetetracarboxylic dianhydride and 4,4°-diaminodiphenyl ether, pyromellitic dianhydride and 3,3-diaminodiphenylsulfone, pyromellitic dianhydride and 3,3°, 4.4'-benzophenone tetracarboxylic dianhydride and 3,3-(or 4.4'-)diaminodiphenylsulfone, 3.3°
, 4,4°-benzophenonetetracarboxylic dianhydride and 3,3°-(or 4,4°-)diaminodiphenylsulfone, 3.3°,4,4°-biphenyltetracarboxylic dianhydride and 3.3'-(or 4.4'-)diaminodiphenylsulfone, 3.3°, 4,4°-biphenyltetracarboxylic dianhydride and 3,3°,4,4-penzophenonetetracarboxylic acid Acid dianhydride and 3,3°-(or 4,4°-)diaminodiphenylsulfone, pyromellitic dianhydride and 4,4°-diaminodiphenyl ether and bis(3-aminopropyl)tetramethyldisiloxane, pyromellitic dianhydride and 4,4°-diaminodiphenyl ether, Mellitic dianhydride and 3,3°,4,4°-benzophenonetetracarboxylic dianhydride and 4,4°-diaminodiphenyl ether and bis(3-aminopropyl>tetramethyldisiloxane, 3.3°,4 ,4-
Benzophenone tetracarboxylic dianhydride and 4,4°-
Diaminodiphenyl ether and bis(3-aminopropyl)tetramethyldisiloxane, 3.3°,4,4-biphenyltetracarboxylic dianhydride and 4,4°-diaminodiphenyl ether and bis(3-aminopropyl)tetramethyldisiloxane. Siloxane, 3.3°, 4.4'-biphenyltetracarboxylic dianhydride and 3,3°, 4.4'-benzophenonetetracarboxylic dianhydride, 4,4'-diaminodiphenyl ether and bis(3- aminopropyl) tetramethyldisiloxane, pyromellitic dianhydride and 3,3°-(or 4.4'-
) diaminodiphenylsulfone and bis(3-aminopropyl)tetramethyldisiloxane, pyromellitic dianhydride and 3,3",4,4°-benzophenonetetracarboxylic dianhydride and 3,3°-(or 4 ,4°−
) diaminodiphenylsulfone and bis(3-aminopropyl)tetramethyldisiloxane, 3.3°:4,4-benzophenonetetracarboxylic dianhydride and 3.3'-(or 4,4°-)diaminodiphenylsulfone and bis(3-aminopropyl)te(~
3.3°, 4.4′-biphenyltetracarboxylic dianhydride and 3.3′-(or 4.4′-)diaminodiphenylsulfone and bis(3-aminopropyl)tetramethyldisiloxane. Siloxane, 3.3°, 4,4-biphenyltetracarboxylic dianhydride and 3,3°, 4,4°-benzophenonetetracarboxylic dianhydride and 3,3°-(or 4./l'- ) A polyamic acid synthesized from diaminodiphenylsulfone, bis(3-aminopropyl)tetramethyldisiloxane, etc. is preferably used.

The third amine compound in the present invention is represented by the following general formula [A], where R3, R4, and R5 are hydrocarbon groups having 1 to 30 carbon atoms, and each of R3 to R5 is as follows. It can contain various substituents and bonding groups, and n is 1, 2.3. ) is preferably used.

Preferred specific examples include trimethylamine, 1-ethylamine, 1-ri-n-
Propylamine, tri-n-butylamine, methyldiethylamine, dimethyl-〇-propylamine, N,N-
Dibutyl-2-ethylhexylamine, tomethyldiallylamine, 3-dimethylamitublobanol, N-isobutylgetanolamine, dimethyl-3-dimethoxypropylamine, N,N,N"N'-tetramethyl-1
,2-diaminoethane, N,N,N',N'-tetramethyldiaminopropane, N,N,N',N'-tetraallyl-1,4-diaminobutane, N,N,N',N'-
Examples include pentamethyldiethylenetriamine, N,N-dimethylbenzylamine, dimethylaminoacetaldehyde diethyl acetal, 2-dimethylaminoethyl acetate, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, etc. Not limited to these.

In particular, it is preferable to use a highly basic aliphatic tertiary amine because the transparency of the coating film is further improved.

Particularly preferred specific examples include, but are not limited to, triethylamine, tripropylamine, tributylamine, 2-dimethylaminoethyl acetate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl acrylate, etc. .

These compounds may be used alone or in combination
It may be used as a mixture of more than one species.

In addition, primary amines, secondary amines, quaternary amines, and organic basic compounds such as pyridine derivatives and imidazole derivatives may be used within the range that does not adversely affect coating properties, solution stability, and coating film transparency. may be added.

The amount of tertiary amine added is preferably 0.3 to 4.0 equivalents, more preferably 0.5 to 3.0 equivalents, based on the carboxyl group of the polyamic acid. It is preferable to add O equivalent. If the amount is less than the lower limit, the effect of promoting imide ring closure and the effect of improving the transparency of the coating cannot be sufficiently compared, and if the amount is added above the upper limit, A, B, C
The viscosity stability of the composition during storage deteriorates.

The silanol compound [nl] in the present invention is a compound having a structure represented by the above general formula [■], which can be dehydrated and condensed by heating to form a siloxane structure.

Further, a partial condensate of a silanol compound refers to a compound in which a portion of a silanol group is dehydrated and condensed to form a siloxane structure. Usually these are obtained as mixtures of dimers, trimers, tetramers and higher condensates.

In the above structural formula [nl, R3 is a monovalent group with 1 carbon number]
~20 alkyl groups, allyl groups, aromatic groups, alkoxy groups, and vinyl groups are preferred.

As a more preferable specific example of R3, Ct-Is
-, C2H5-, (CH3)2CH-.

(CH3)2CHCH2+, (CCto13>20
1-(CH2CH2-, (OCH3)-, (CC2t-
Is)-, (OC3H?)-, CeHs-, CH2=
Examples include, but are not limited to, C1''- and the like.

In addition, in the compound of the structural formula [nl, R3 is only one of these
It may be composed of a species, or it may be composed of two or more species.

These compounds are provided in the form of a solution in an organic solvent containing alcohol as a main component. As the alcohol, aliphatic alcohols such as methanol, ethanol, butanol are preferably used.

As the silanol compound [II] that can be used, for example, ethyl silicate 40. Examples include "O, C, D," manufactured by Tokyo Ohka Kogyo Co., Ltd.

The amount S (wt%) of the silanol compound [nl or its partial condensate] is preferably 0.5 to 90 (wt%), more preferably 2 to 80 (wt%). Note that the addition of the silanol compound = s (wt%) is given by the following formula.

5i02 amount (g) S (wt%) = x
100Si02ω ((]) + polyamide acid amount ((])
If it is added in an amount below the lower limit, the effect of improving properties will not be significant, and if it is added in an amount exceeding the upper limit, the coating film forming ability will deteriorate.

Next, an example of a method for manufacturing a liquid crystal display element of the present invention will be explained.

The polyamic acid having the structural unit [I] in the present invention is preferably produced by reacting a diamine and a tetracarboxylic dianhydride in an organic solvent at a temperature of about 15°C to 50°C for several hours.

A tertiary amine compound and a silanol compound are added and mixed to the resulting polymer solution, the viscosity and 0 degrees are adjusted with a diluent, and the mixture is filtered and used.

Examples of organic solvents and diluents used in this reaction are:
Examples include aprotic polar solvents such as N-methyl-2-pyrrolidone and N,N-dimethylacetamide.

Next, it is coated on the glass substrate provided with the 5i02 layer and the conductive layer by a method such as a printing method, and is heat-treated to form a heat-treated film according to the present invention.

The film thickness is usually around 1,000 J: Applied, 20
Heat treated at a temperature of 0'C to 300C for 30 to 60 minutes. The alignment film can be obtained by lightly rubbing the heat-treated film with a cotton cloth or the like. The two substrates thus obtained are combined to create a cell.

As the liquid crystal sealed in the liquid crystal display element, any known liquid crystal may be appropriately selected. It may be a nematic type liquid crystal or a ferroelectric smectic type liquid crystal.

In the manner described above, the liquid crystal display element of the present invention can be obtained.

[Function] In the composition comprising the polyamic acid of the @structuring unit [I] of the present invention, a silanol compound, and a tertiary amine compound,
The tertiary amine has the effect of improving the transparency of the film, promoting imide ring closure, and promoting the condensation of silanol compounds.

Therefore, it is thought that due to these interactions, sufficient film performance can be obtained even when heat-treated at low temperatures.

[Example] The present invention will be explained based on examples.

Examples 1 to 5 110 Cl of diaminodiphenyl ether was dissolved in 278 g of N-methylpyrrolidone to prepare an amine solution. Anhydrous pyromellitone 1120c] was dispersed in 308 g of dimethylacetamide, and then N-methylpyrrolidone 18
4q was added and dissolved to obtain an M 2U solution. By adding an acid solution to the amine solution and reacting at 60°C for 3 hours, a solution (A>) of 60 poise at 30°C was obtained.

A tertiary amine compound as shown in Table 1 was added to the solution (A) in an amount equivalent to the polyamic acid, and γ-aminopropyltriethoxysilane was added as an adhesion improver in 11.
50 and mixed. Next, as a silanol compound, ethyl silicate 40 or OCD T manufactured by Tokyo Ohka Kogyo Co., Ltd.
YPE2 was added only as much as listed in Table 1, and after mixing, N-methyl-2-
A coating solution was obtained by diluting with pyrrolidone and filtering.

It was coated on a glass substrate with an In2O3 transparent electrode using a spinner and heated at 250° C. for 1 hour to form a film with a thickness of 1000 μm. An alignment film was formed by rubbing in a certain direction with a cotton cloth. After removing the polyimide in the sealed portions of the two glass substrates thus obtained by plasma etching, they were sealed using epoxy resin to form cells. Next, thick-type nematic liquid crystal was injected, and a liquid crystal display element was completed. After being left in an atmosphere of 70° C. and 95% RH for 100 hours, the light was turned on and the occurrence of bleeding was examined. The results are shown in Table 1.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the tertiary amine compound and silanol compound were not added.

The results are shown in Table 1.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the silanol compound was not added. The results are shown in Table 1.

Comparative Example 3 The same procedure as in Example 1 was carried out except that the tertiary @amine compound was not added. The results are shown in Table 1.

As is clear from the above, the liquid crystal display element of the present invention has two
Under the heat treatment condition of 50°C, it shows good characteristics even after the deterioration test.

[Effects of the Invention] The present invention uses a heat-treated film of a composition comprising a polyamic acid of the structural unit [I], a silanol compound, and a tertiary amine compound as an alignment film, so that even when heat-treated at a low temperature, After the deterioration test, 1q of liquid crystal display elements with no disordered orientation or blurred characters were produced.

Claims (1)

[Claims] (1) In a liquid crystal display element having a liquid crystal alignment film on a substrate on which transparent electrodes are formed, the alignment film has a general formula ▲ mathematical formula, chemical formula, table, etc. ▼ (I) (However , where R_1 is a trivalent or tetravalent organic group, R_2
is a divalent organic group, and m is 1 or 2. ), B, a tertiary amine compound and C, general formula (R_3)_nSi(OH)_4_-_n... [II] (
However, in the formula (R_3) is a monovalent organic group, and n is 1, 2
, 3. ) A liquid crystal display element comprising a heat-treated film of a silanol compound [II] and/or a partial condensate thereof.