JPH0648339B2 - Alignment treatment agent for liquid crystal display cells - Google Patents

Description

TECHNICAL FIELD The present invention relates to an alignment treatment agent for liquid crystal display cells, and more specifically to liquid crystal molecules having an increased tilt alignment angle with respect to a substrate and being transparent. The present invention relates to an alignment treatment agent for liquid crystal display cells, which has excellent properties and heat resistance.

(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 conducted extensive studies to solve the above problems, and as a result, from tetracarboxylic acids having an alicyclic structure and derivatives thereof and diamines having a perfluoroalkyl group, The present invention has been completed by discovering a new fact that an alignment treatment agent for a liquid crystal display cell, which is composed of a polyimide resin having a constitutional repeating unit, has an extremely large tilt alignment angle of liquid crystal molecules with respect to a substrate surface.

That is, the present invention is represented by the general formula [I]. (In the formula, R ¹ and R ² have the same or different carbon numbers 1 to 1
6, a perfluoroalkyl group, R ³ is an organic group constituting a tetracarboxylic acid having an alicyclic structure or a derivative thereof,
R ⁴ , R ⁵ , R ⁶ , and R ⁷ are halogen atoms and have 1 to 4 carbon atoms.
And may represent the same or different from each other, and a, b, c and d are 0, 1, or 2
And n is 0 or 1. ) The constitutional ratio A of the repeating unit is 5 mol% ≦ A <100 mol% and is represented by the general formula [II]. (In the formula, R ⁸ represents an organic group constituting a diamine having no perfluoroalkyl group, and R ⁹ represents an organic group constituting an aromatic tetracarboxylic acid or a derivative thereof.) The constitutional ratio B of repeating units is 95 mols. The present invention relates to an alignment treatment agent for a liquid crystal display cell, which is made of a polyimide resin of% ≧ B> 0 mol%.

The alignment treatment agent for a display cell of the present invention is a liquid crystal that gives an enhanced tilt alignment angle by forming a polyimide resin film on a transparent substrate such as glass or a plastic film with a transparent electrode, and then subjecting it to a rubbing treatment. It is used as an alignment treatment agent for display cells.

The constitutional ratio A of the repeating unit represented by the general formula [I] of the present invention is 5 mol% ≦ A <100 mol% and the constitutional ratio B of the repeating unit represented by the general formula [II] is 95 mol% ≧ A>
A polyimide resin composed of 0 mol% is represented by the general formula [III]. (In the formula, R ³ represents a tetravalent organic group forming a tetracarboxylic acid having an alicyclic structure.) One or more kinds selected from tetracarboxylic acids having an alicyclic structure and derivatives thereof. Represented by a compound and general formula [IV] (In the formula, R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ , a,
b, c, d and n are the same as above. ) Represented by one or more diamine compounds and the general formula [V] (In the formula, R ⁹ is the same as above.) One or more aromatic tetracarboxylic acids and their derivatives and H ₂ N—R ⁸ —NH ₂ [VI] (VI) represented by the general formula [VI]. In the formula, R ⁸ is the same as the above.) One or more diamines are obtained as a starting material.

According to the method of the present invention, the general formula [I] in the polyimide resin is
The tilt orientation angle of the liquid crystal can be freely adjusted by the constitutional ratio of the repeating unit represented by.

That is, the constitutional ratio A of the repeating unit represented by the general formula [I] having a tetracarboxylic acid having an alicyclic structure and its derivative and a diamine residue containing a perfluoroalkyl group as a constitutional component is 5 mol% ≦ By using a polyimide resin in the range of A <100 mol% as a liquid crystal display cell alignment treatment agent, a high liquid crystal tilt alignment angle can be obtained, and the tilt alignment angle can be adjusted within the above range.

If the constitutional ratio A of the repeating unit of the general formula [I] is less than 5% by mole, the effect of increasing the tilt orientation angle is not sufficient.

Specific examples of the tetracarboxylic acid having an alicyclic structure represented by the general formula [III] and derivatives thereof used in the present invention are represented by the general formula [VII], [VIII], [IX] or [X]. Ru (In the formula, m ¹ , m ² , m ³ and m ⁴ are integers of 0, 1 or 2 and may be the same or different from each other.) Tetracarboxylic acid having a monocyclic structure or a polycyclic structure And derivatives thereof such as dianhydrides and dicarboxylic acid halides.

Specific examples thereof include cyclobutane tetracarboxylic acid,
Examples thereof include cyclopentanetetracarboxylic acid, cyclohexanetetracarboxylic acid and dianhydrides thereof, and further dicarboxylic acid dihalide.

Specific examples of the diamine compound represented by the general formula [IV] include 1,1,
1,3,3,3-hexafluoro-2,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,1,1,3,3,3-hexafluoro-2,2-bis [ 3,5-dimethyl-4- (4-
Aminophenoxy) phenyl] propane, 1,1,1,3,3,3
-Hexafluoro-2,2-bis [3,5-dibromo-4 (4
-Aminophenoxy) phenyl] propane, 1,1,1,3,3,
3-hexafluoro-2,2-bis [3-methyl-4- (4
-Aminophenoxy) phenyl] propane, 1,1,1,3,3,
3-hexafluoro-2,2-bis [4- (3-aminophenoxy) phenyl] propane, 1,1,1,3,3,4,4,4-octafluoro-2,2-bis [4- (4-Aminophenoxy) phenyl] butane, 1,1,1,2,2,4,4,5,5,5-decafluoro-3,3-bis [4- (4-aminophenoxy) phenyl] pentane , 1,1,1,3,3,3-hexafluoro-2,2
-Bis (4-aminophenyl) propane, 1,1,1,3,3,3
-Hexafluoro-2,2-bis (3-aminophenyl)
Propane, 1,1,1,3,3,3-hexafluoro-2,2-bis (3-methyl-4-aminophenyl) propane, 1,1,1,
3,3,4,4,4-octafluoro-2,2-bis (4-aminophenyl) butane and the like can be mentioned.

Specific examples of the aromatic tetracarboxylic acid of the general formula [V] and its derivatives include aromatic tetracarboxylic acids such as pyromellitic acid, benzophenonetetracarboxylic acid and biphenyltetracarboxylic acid, and their dianhydrides, and Examples thereof include dicarboxylic acid dihalides.

Further, specific examples of the diamine of the general formula [VI] 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-aminophenoxy) diphenyl sulfone, 2,2-
Aromatic diamines such as bis- [4- (4-aminophenoxy) phenyl] propane, diaminodicyclohexylmethane, diaminodicyclohexyl ether, alicyclic diamines such as diaminocyclohexane, 1,2-diaminoethane, 1,3-diaminopropane , 1,4-diaminobutane, 1,
Aliphatic diamines such as 6-diaminohexane may be mentioned.

The method for producing the polyimide resin comprising the repeating units of the general formulas [I] and [II] of the present invention is not particularly limited, but in general, one or two or more general formulas [II
I] Tetracarboxylic acid dianhydride and diamine of the general formula [IV] are reacted and polymerized in an organic solvent in a molar ratio of 0.50 to 0.99 or 2.00 to 1.01, and then the repeating unit of the general formula [I] is used. Within the range of 5 mol% or more and less than 100 mol% to the desired mol% and further within the range represented by the following relational expression. A method of adding a predetermined amount of a tetracarboxylic dianhydride of the general formula [V] and a diamine of the general formula [VI], reacting and polymerizing to obtain a polyimide resin precursor, and then dehydrating and ring-closing to form a polyimide resin. Can be adopted.

In this case, the reaction polymerization temperature of the tetracarboxylic dianhydride of the general formula [V] and the diamine of the general formula [VI] is −20 to 1
Any temperature of 50 ° C. can be employed, but especially −
The range of 5 to 100 ° C is preferable.

Furthermore, a solution method is usually suitable as a method for polymerizing the polyimide resin precursor.

Specific examples of the solvent used in the solution polymerization method, N, N-
Dimethylformamide, N, N-dimethylacetamide,
Examples thereof include N-methylpyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethylurea, pyridine, dimethyl sulfone, hexamethylphosphoamide and butyrolactone.

These may be used alone or in combination.

Furthermore, even if the solvent does not dissolve the polyimide resin precursor, the solvent may be added to the above-mentioned solvent within the range where a uniform solution can be obtained.

Further, in order to add the polyimide resin precursor to the polyimide resin, a method of dehydration ring closure by heating is usually adopted.

The heat dehydration ring-closing temperature can be selected from any temperature of 150 to 450 ° C, preferably 170 to 350 ° C.

The time required for this dehydration ring closure is 30 depending on the reaction temperature.
Seconds to 10 hours, preferably 5 minutes to 5 hours are suitable.

As another method of converting the polyimide resin precursor into a polyimide resin, a known dehydration ring-closing catalyst may be used for ring closure.

In the present invention, the constitutional ratio A of the repeating unit of the general formula [I] is 5 mol% ≦ A <100 mol% and the constitutional ratio B of the repeating unit of the general formula [II] is 95 mol% ≧ B> 0. Mol%
The polyimide resin consisting of or a polyimide resin precursor solution thereof is applied on a transparent substrate such as 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 to 2 hours. A polyimide resin film having a cured film thickness of 200 to 3000 Å is formed, and then the resin film is rubbed to be used as an alignment treatment agent for liquid crystal display cells.

(E) Effect of the Invention The alignment treatment agent for liquid crystal display cells of the present invention can be used as an alignment treatment agent for liquid crystal display cells having a large liquid crystal tilt alignment angle.

Further, the constitutional ratio A of the repeating unit of the general formula [I] of the polyimide resin used as an alignment treatment agent for liquid crystal display cells is
The liquid crystal tilt alignment angle is arbitrarily adjusted as long as 5 mol% ≦ A <100 mol% and the constitutional ratio B of the repeating unit of the general formula [II] is 95 mol% ≧ B> 0 mol%. It is possible.

(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 1,1,1,3,3,3-hexafluoro-2,2-bis [4- (4-
Aminophenoxy) phenyl] propane (hereinafter HFB
It is abbreviated as PA. ) 32.63 g (0.063 mol) and 11.76 g (0.06 mol) of cyclobutane tetracarboxylic acid dianhydride were stirred in 430 g of N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP) at room temperature for 3 hours to react. After that, 1.96 g (0.009 mol) of pyromellitic dianhydride, 4,4'-
1.40 g (0.007 mol) of diaminodiphenyl ether was sequentially added, and the reaction was further performed at room temperature for 3 hours to prepare a polyimide resin precursor solution.

The reduced viscosity η _{SP / C} of the obtained polyimide resin precursor solution is
It was 0.78 d / g (0.5 wt% NMP solution, 30 ° C.).

After diluting this solution with NMP to a total solid content of 2% by weight,
A glass substrate with a transparent electrode is spin-coated at 3500 rpm and then heat-treated at 250 ° C. for 60 minutes to give a thickness of 1000.
A polyimide resin film of ˜1500Å was formed.

After rubbing this polyimide resin film with a cloth, assemble it with rubbing directions parallel to each other with a 50μ spacer in between.
Next, a liquid crystal (ZL1-2293 manufactured by Merck & Co., Inc.) was injected to prepare a homogeneously aligned cell.

When this cell was rotated in crossed Nicols, clear light and darkness was observed, 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 crystal rotation method and found to be 9.3 °.

The cell was stable for a long time.

Example 2 18.13 g (0.035 mol) of HFBPA and 5.88 g (0.03 mol) of cyclobutanetetracarboxylic dianhydride were added to NMP39.
After stirring in 2 g at room temperature for 3 hours, 3,3 ', 4,4'-
Benzophenone tetracarboxylic acid dianhydride 12.56 g (0.0
399 mol), 4,4'-diaminodiphenyl ether 7.0 g
(0.035 mol) were sequentially added, and the reaction was further performed at room temperature for 3 hours to prepare a polyimide resin precursor solution.

The reduced viscosity η _{SP / C} of the obtained polyimide resin precursor solution is
It was 0.80 d / g (0.5 wt% NMP solution, 30 ° C.).

Using this polyimide resin precursor solution, dilution, spin coating and heat treatment were carried out in the same manner as in Example 1 to form a polyimide resin film, and then cells were prepared.

The liquid crystal tilt orientation angle of this cell was 6.9 °, the orientation was good, and it was stable for a long time.

Comparative Example 1 1.45 g (0.0028 mol) of HFBPA, 0.53 g (0.0027 mol) of cyclobutanetetracarboxylic dianhydride, 14.45 g (0.063 mol) of pyromellitic dianhydride, 13.44 g (0.0672 mol) of 4,4'-diaminodiphenyl ether and NMP26
A polyimide resin precursor solution was prepared in the same manner as in Example 1 except that the amount was 9 g.

Using this polyimide resin precursor solution, dilution, spin coating and heat treatment were carried out in the same manner as in Example 1 to form a polyimide resin film, and then cells were prepared.

The tilt orientation angle of this cell was as low as 2.6 °.

Comparative Example 2 Without using HFBPA, 11.76 g (0.06 mol) of cyclobutanetetracarboxylic dianhydride, pyromellitic anhydride 1.9
6 g (0.009 mol) and diaminodiphenyl ether 14.0
g (0.07 mol) was reacted in 249 g of NMP at room temperature with stirring for 3 hours to prepare a polyimide resin precursor solution.

The reduced viscosity η _{SP / C} of the obtained polyimide resin precursor resin is
It was 0.90 d / g (0.5 wt% NMP solution, 30 ° C.).

Using this polyimide resin precursor solution, dilution, spin coating and heat treatment were carried out in the same manner as in Example 1 to form a polyimide resin film, and then cells were prepared.

The liquid crystal tilt alignment angle of this cell was as low as 3.2 °.

Claims (1)

[Claims] 1. An alignment treatment agent for a liquid crystal display cell, which is applied on a transparent substrate with a transparent electrode, heat-cured, and then rubbed to form an alignment treatment layer of a liquid crystal, wherein the treatment agent comprises:
General formula [I] (In the formula, R ¹ and R ² are the same or different from each other and have 1 carbon atoms.
To 6 are perfluoroalkyl groups, R ³ is an organic group constituting a tetracarboxylic acid having an alicyclic structure or a derivative thereof, and R ⁴ , R ⁵ , R ⁶ and R ⁷ are halogen atoms and have 1 to 10 carbon atoms. 4 are alkyl groups or alkoxy groups and may be the same or different from each other, and a, b, c and d are 0, 1
Or 2, and n is 0 or 1. ), The constitutional ratio A of the repeating unit is 5 mol% ≦ A <100 mol% and the general formula [II] (In the formula, R ⁸ represents an organic group forming a diamine having no perfluoroalkyl group, and R ⁹ represents an organic group forming an aromatic tetracarboxylic acid or a derivative thereof.) B is 95 mol% ≧ B>
An alignment treatment agent for liquid crystal display cells, which comprises 0 mol% of a polyimide resin.