JPH0648336B2 - Method for forming liquid crystal alignment treatment layer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a liquid crystal alignment treatment layer, and more specifically, a liquid crystal alignment in which liquid crystal molecules have an increased tilt alignment angle with respect to a substrate. The present invention relates to a method for forming a treatment layer.

(B) Conventional technology As a substrate treating agent for orienting nematic liquid crystal molecules almost parallel to a transparent substrate such as glass or a plastic film with a transparent electrode, organic resin films such as polyimide resin film have been conventionally used. Most commonly used.

In this case, by rubbing the organic resin film formed on the substrate with a cloth in a certain direction, liquid crystal molecules are aligned in the rubbing direction, and at the same time, a liquid crystal tilt alignment angle of about 1 to 3 ° is usually formed with respect to the substrate surface. Is known to cause

Further, as a method of largely orienting liquid crystal molecules, a method of depositing an inorganic film such as silicon oxide on a substrate has been conventionally performed.

(C) Problems to be Solved by the Invention It is difficult to largely orient the liquid crystal molecules by the method of rubbing the organic resin film formed on the substrate.

Further, the method of depositing an inorganic film on a substrate is more complicated than the rubbing method, and is not necessarily an appropriate method in actual industrial production.

(D) Means for Solving the Problems The inventors of the present invention have completed the present invention as a result of diligent studies to solve the above problems.

That is, the present invention relates to a method for forming a liquid crystal alignment treatment layer, which comprises applying a liquid crystal alignment treatment agent to a transparent substrate with a transparent electrode, heat-curing it, and then rubbing it.
I] (In the formula, R ¹ represents a hydrocarbon group having 6 to 20 carbon atoms, R ² ,
R ^3's each represent the same or different hydrocarbon group having 4 to 20 carbon atoms. ) Represented by at least one compound selected from amino compounds and the general formula [III] (In the formula, R ⁴ is a tetravalent organic group constituting a tetracarboxylic acid or a derivative thereof, R ⁵ is a divalent organic group constituting a diamine, and n is a positive integer.) Liquid crystal comprising a polyimide resin precursor The present invention relates to a method for forming a liquid crystal alignment treatment layer characterized by using an alignment treatment agent.

The method for forming a liquid crystal alignment treatment layer of the present invention comprises applying a liquid crystal alignment treatment agent used in the method of the present invention on a transparent substrate such as glass or a plastic film having a transparent electrode, and after curing,
By forming a polyimide resin film and then performing a rubbing treatment.

The organic group R ¹ of the amine compound of the general formula [I] used in the liquid crystal alignment treatment agent used in the method of the present invention has 6 to 20 carbon atoms.
And examples thereof include an alkyl group, a nuclear-substituted or non-nuclear-substituted aryl group, an aralkyl group, and a cycloalkyl group.

When the organic group R ¹ has 5 or less carbon atoms, the effect of increasing the tilt alignment angle of the liquid crystal molecules is not sufficient.

Further, if the carbon number exceeds 20, problems such as deterioration of coating property on the substrate are likely to occur.

Specific examples of the amine compound represented by the general formula [I] include n-hexylamine, n-octylamine, n-decylamine, n-dodecylamine, n-hexadecylamine, 1,
3-dimethylbutylamine, 1,5-dimethylhexylamine, 2-ethylhexylamine, p-aminobiphenyl, p-aminoethylbenzene, benzylamine, p-
Examples thereof include methylbenzylamine and 4-ethylcyclohexylamine.

Further, the organic groups R ² and R ³ of the amine compound of the general formula [II]
Are the same or different hydrocarbon groups having 4 to 20 carbon atoms.

For the same reason as the above-mentioned amine compound of the general formula [I], R
^The number of carbon atoms of ² and R ³ is appropriately in the range of 4 to 20, and examples of the hydrocarbon groups R ² and R ³ include an alkyl group, a nuclear-substituted or non-nuclear-substituted aryl group, an aralkyl group and a cycloalkyl group. .

Specific examples of the amine compound represented by the general formula [II] include di-n-
Butylamine, di-i-butylamine, di-n-amylamine, di-i-amylamine, di-n-hexylamine, di-n-octylamine, di-n-dodecylamine, di-n-hexadecylamine, di -Benzylamine, diphenylamine, dicyclohexylamine and the like.

Further, the polyimide resin precursor of the general formula [III] used in the liquid crystal alignment treatment agent used in the method of the present invention is represented by the general formula [IV] (In the formula, R ⁴ represents a tetravalent organic group constituting tetracarboxylic acid, and the four carbonyl groups bonded to R ⁴ are directly bonded to different carbon atoms.) Tetracarboxylic acid and its One or more compounds selected from derivatives and H ₂ N—R ⁵ —NH ₂ [V] represented by the general formula [V] (In the formula, R ⁵ is a divalent organic group constituting diamine. It is obtained by reacting diamine.

Specific examples of the tetracarboxylic acid of the general formula [IV] and its derivatives include aromatic tetracarboxylic acids such as pyromellitic acid, benzophenonetetracarboxylic acid, and 3,4,3 ', 4'-biphenyltetracarboxylic acid, and these. Dianhydride and dicarboxylic acid diacid halide, cyclobutanetetracarboxylic acid, cyclopentanetetracarboxylic acid, alicyclic tetracarboxylic acid such as cyclohexanetetracarboxylic acid, and dianhydrides thereof and dicarboxylic acid diacid thereof Examples thereof include halides, aliphatic tetracarboxylic acids such as butanetetracarboxylic acid, dianhydrides thereof, and dicarboxylic acid diacid halides thereof.

The tetracarboxylic acid of the general formula [IV] and its derivative may be used alone or in combination of two or more.

Specific examples of the amine of the general formula [V] include p-phenylenediamine, m-phenylenediamine, diaminodiphenylmethane, diaminodiphenyl ether, 2,2-diaminodiphenylpropane, diaminodiphenylsulfone, diaminobenzophenone, diaminonaphthalene, 1,
3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4'-di (4-
Aromatic diamines such as aminophenoxy) diphenyl sulfone and 2,2'-bis [4 (4-aminophenoxy) phenyl] propane.

Other alicyclic diamines and aliphatic diamines may be used depending on the purpose.

Further, one kind or a mixture of two or more kinds of these diamines can be used.

The amine compounds represented by the general formulas [I] and [II] of the liquid crystal alignment treatment agent used in the method of the present invention can be used alone or in combination of two or more kinds.

The amount of the amine compound of the general formula [I] and the general formula [II] used is not particularly limited, but is preferably in the range of 1 to 100% by weight based on the polyimide resin precursor of the general formula [III].

That is, within the above range, the orientation angle of the liquid crystal molecules can be arbitrarily adjusted by the amount of the amine compound of the general formula [I] and the general formula [II] used.

If the amount of the amine compound of the general formula [I] and the general formula [II] used is less than 1% by weight, the effect may not be sufficiently observed, and if it exceeds 100% by weight, the coating property on the substrate may deteriorate. Inconvenience tends to occur.

A solvent is used to prepare the liquid crystal alignment treatment agent used in the method of the present invention. These solvents are not particularly limited as long as they dissolve the compounds of the general formulas [I] and [II] and the polyimide resin precursor of the general formula [III].

Specific examples of these solvents include N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethylurea, pyridine, dimethyl sulfone, hexamethylphosphoramide and Butyrolactone and the like can be mentioned.

These may be used alone or in combination.

Furthermore, even if the solvent alone does not provide a uniform solution,
The solvent may be used in addition to the above solvent as long as a uniform solution can be obtained.

The amount of the solvent used is such that the amine compounds of the general formulas [I] and [II] (hereinafter simply referred to as amine compounds) and the polyimide resin precursor of the general formula [III] are uniformly dissolved. The amount may be in the range of 0.5 to 100 parts by weight based on 1 part by weight of the total amount of the amine compound and the polyimide resin precursor of the general formula [III].

As a method for preparing the liquid crystal alignment treatment agent used in the method of the present invention,
(1) a method of simultaneously dissolving an amine compound and a compound of the general formula [III], (2) a method of dissolving the compound of the general formula [III] in a solvent, and then adding and dissolving the amine compound, (3) an amine compound After the compound is dissolved in a solvent, a compound of the general formula [III] is added and dissolved, (4) an amine compound and a general formula [I
A method in which the compounds of II] are separately dissolved in a solvent and then mixed. (5) A method of adding the amine compound or a solution thereof dissolved in a solvent after the compound of the general formula [III] is produced can be mentioned.

The liquid crystal alignment treatment agent used in the method of the present invention thus obtained is applied on a transparent substrate such as a glass or plastic film having a transparent electrode by a spin coating method or a printing method, and then at 150 to 250 ° C. for 1 minute. The liquid crystal alignment treatment layer can be formed by the method of the present invention by curing for 2 hours to form a polyimide resin film having a film thickness of 200 to 3000 Å and then rubbing the polyimide resin film layer.

(E) Effects of the Invention The liquid crystal tilt alignment angle can be increased by the method for forming a liquid crystal alignment treatment layer of the present invention.

In addition, the liquid crystal tilt alignment angle is calculated by the general formula [I] and the general formula [II].
It is possible to arbitrarily adjust the amount by changing the amount of the amine compound used.

(F) Examples The present invention will be described in more detail below with reference to Examples, but the present invention is not limited thereto.

Example 1 A commercially available polyimide resin precursor solution [trade name: manufactured by Nissan Chemical Industries, Ltd .: SanEver 130, 15 wt% N-2-methylpyrrolidone (hereinafter abbreviated as NMP) solution] was polyimide-containing n-hexadecylamine. 1 for resin precursor component
It was added so as to be 0% by weight, and the total solid content was diluted to 2% by weight with NMP, and then sufficiently stirred to obtain a uniform solution.

This solution was spin-coated on two glass substrates with transparent electrodes and heat-treated at 170 ° C. for 60 minutes to give a thickness of 10
A polyimide resin coating film of 00 to 1500Å was formed.

After rubbing this coating film with a cloth, assemble it with a 5μ spacer in between with the rubbing direction parallel.
(Manufactured by the company: E-7) was injected to prepare a homogeneously oriented cell.

When this cell was rotated in crossed Nicols, clear light and dark were seen, and it was confirmed that the cell was well oriented in the rubbing direction.

The liquid crystal tilt alignment angle of this cell was measured by the magnetic field capacitance method and found to be 12 °.

Example 2 When the same treatment as in Example 1 was carried out except that n-hexadecylamine was changed to n-octylamine, the liquid crystal tilt alignment angle was 6 ° and the alignment was good.

Example 3 The same treatment as in Example 1 was carried out except that the amount of n-hexadecylamine was changed to 3% by weight based on the polyimide resin precursor, and the liquid crystal tilt alignment angle was 6 ° and the alignment was good.

Example 4 The same process as in Example 1 was carried out except that the liquid crystal was changed to ZLI-2293 (manufactured by Merck), and the liquid crystal tilt alignment angle was 15
And the orientation was good.

Example 5 When the same treatment as in Example 1 was carried out except that a spacer having a thickness of 6 μm was used, the liquid crystal tilt alignment angle was 15 ° and the alignment was good.

Comparative Example When the same treatment as in Example 1 was carried out except that n-hexadecylamine was not used, the liquid crystal tilt alignment angle was 2.4 °.

Claims (2)

[Claims] 1. A method for forming a liquid crystal alignment treatment layer, comprising applying a liquid crystal alignment treatment agent to a transparent substrate with a transparent electrode, heating and curing, and then rubbing treatment, which is represented by the following general formula [I] and general formula [II]. Ru (In the formula, R ¹ is a hydrocarbon group having 6 to 20 carbon atoms, R ² or R ² .
³ each represents the same or different hydrocarbon group having 4 to 20 carbon atoms. ) At least one compound selected from amine compounds and represented by the general formula [III] (In the formula, R ⁴ is an organic group constituting a tetracarboxylic acid or a derivative thereof, R ⁵ is a divalent organic group constituting a diamine,
n represents a positive integer. ) A method for forming a liquid crystal alignment treatment layer, which comprises using a liquid crystal alignment treatment agent comprising a polyimide precursor. 2. A method according to claim 1, wherein R ^{1 of the} amine compound represented by the general formula [I] is CH ₃ CH ₂ (m represents a positive integer of 5 to 19). A method for forming a liquid crystal alignment treatment layer according to the description.