JPH06250191A - Oriented film for liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide the oriented film adequately usable for the liquid crystal display element of a TFT system, STN system or ferroelectric system in order to stably develop a high liquid crystal pretilt angle by incorporating a polymer incorporated with a specific repeating unit in its main chain. CONSTITUTION:This oriented film contains the polymer incorporated with the repeating unit expressed by formula I in its main chain. In the formula I, R1, R2 are bivalent org. groups and R3 are a univalent org. group. R1 is a bivalent org. group constituting dicarboxylic acid and exhibits excellent characteristics as the oriented film for the liquid crystal display element in the case of the structure expressed by formula II. R2 is a bivalent org. group constituting diamine and exhibits excellent characteristics as the oriented film for the liquid crystal display element in the case of the structure expressed by formula III. In the formula III, R4, R5, R6, R7, R8, R9, are any of a hydrogen atom, 1 to 8 alkyl group, alkoxy group or trifluoromethyl group.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an alignment film for a liquid crystal display device.

[0002]

2. Description of the Related Art Conventionally, there has been known a method of using an organic polymer film such as polyvinyl alcohol, polyamide resin or polyimide resin as an alignment film for a liquid crystal display. In particular, the polyimide resin is widely used as a liquid crystal alignment film because it has the function of aligning various liquid crystals and is excellent in heat resistance and the like. However, as the characteristics of liquid crystal displays have been improved in recent years, the characteristics of the alignment film material have been required to be better than ever. Specifically, it exhibits good liquid crystal alignment characteristics such as stably giving a high pretilt angle, and has excellent electro-optical characteristics such as high voltage holding ratio and low power consumption. Among these, the pretilt angle of the liquid crystal has a characteristic that directly affects the visual characteristics of the liquid crystal display, and particularly in the case of STN type, TFT type, and ferroelectric type displays, it is very possible to give a stable high pretilt angle. Importantly, current alignment layers do not fully meet that need.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned drawbacks and provides an alignment film for a liquid crystal display device, which provides a stable and high pretilt angle.

[0004]

The present invention is an alignment film for a liquid crystal display device, characterized in that it contains a polymer having a repeating unit represented by the formula (1) in the main chain. .

[Chemical 1] (Here, R ₁ and R ₂ are divalent organic groups, and R ₃ is a monovalent organic group)

In the formula (1), R ₁ is a divalent organic group constituting a dicarboxylic acid. Among them, the structure shown below shows excellent properties as an alignment film for a liquid crystal display device. Furthermore, among these, in the case of a 1,4-cyclohexyl group, more excellent orientation characteristics, high voltage holding characteristics,
Furthermore, it shows a very low current consumption value.

[Chemical 2]

Further, R ₂ in the formula (1) is a divalent organic group constituting diamine, and particularly when it has the structure shown below, it shows excellent properties as an alignment film for a liquid crystal display device.

[Chemical 3] (Here, R ₄ , R ₅ , R ₆ , R ₇ , R ₈ , and R ₉ are each a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group, or a trifluoromethyl group.)

Further, the R ₃ group bonded to the amide nitrogen in the formula (1) is a monovalent organic group. Among them, particularly an organic group having 6 or more carbon atoms, more preferably 6 or more carbon atoms. When it is an organic group containing an aromatic ring or an aliphatic ring, it exhibits particularly good liquid crystal uniaxial orientation and a stable high pretilt angle. Further, when R ₃ is an organic group having 2 or more carbon atoms and containing 3 or more fluorine atoms, a higher pretilt angle is stably given, and an excellent alignment film for liquid crystal display device is obtained.

The R ₃ group of the formula (1) is preferably introduced into 30% or more, preferably 50% or more, more preferably 70% or more of all amide nitrogen atoms of the polymer. R ₃
When the group introduction rate is 30% or less, the effect of improving the pretilt angle of the liquid crystal is small, and it is soluble only in a highly polar solvent system containing NMP or the like as a main component, which causes inconveniences in the alignment agent coating and printing processes. It's easy.

In the present invention, the polyamide-based polymer containing the formula (1) can be used alone, but it can stably exhibit a high pretilt angle even when used in combination with other polymers. At that time, the other polymer is represented by the formula (1):
Polyamide, polyimide in which all R ₃ groups of are hydrogen atoms,
Polyamic acid etc. are mentioned. Also, the equation (1) in that case
The proportion of the polyamide containing is preferably 0.5% or more by weight. When it is 0.5% or less, the effect of stably exhibiting a high pretilt angle is reduced.

To obtain the polyamide polymer of the present invention,
A known method can be applied, and various conditions are not particularly limited, but the following method is generally performed. First, when the raw materials are dicarboxylic acid and diamine, N-methyl-2-pyrrolidone (NM
P), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc) and the like in a mixed solvent system of pyridine and coexisting with triphenyl phosphite, lithium chloride and the like to react with polyamide To synthesize. When an acid halide such as dicarboxylic acid dichloride is used as the dicarboxylic acid raw material, it is reacted with a diamine compound in the presence of triethylamine or pyridine in a solvent such as NMP or DMAc to synthesize a polyamide. Next, the polyamide thus obtained is dissolved in dimethyl sulfoxide (DMSO), potassium hydroxide is added, and then R ₃ -Cl or R ₃ -Br is added.
A polymer of formula (1) is synthesized by adding a halide such as.

When forming a liquid crystal alignment film, a polyamide-based polymer containing a repeating unit represented by the formula (1) obtained by the above-mentioned reaction in the main chain is dissolved in a solvent. Then, after applying this solution to the substrate, the solvent is removed by heating. The solvent is not limited as long as the polyamide polymer is uniformly dissolved, for example, NMP, DMF, DM
Ac, γ-butyrolactone, butyl cellosolve, ethyl cellosolve, diglyme, ethyl carbitol and the like can be mentioned, and these can be used alone or in a mixture of two or more kinds. The coating on the substrate is carried out by a method such as spin coating or printing, and the baking condition is generally 100 ° C. or higher, although it depends on the solvent used.

[0012]

EXAMPLES Examples of the present invention will be described in detail below.
The invention is in no way limited by these examples.

(Synthesis Example 1) 500 ml equipped with a thermometer, a stirrer, a raw material charging port, a reflux condenser and a dry nitrogen gas inlet
In a four-necked separable flask, 1,4-cyclohexanedicarboxylic acid 13.78 g (0.08 mol), 2,2-bis (4- (4-aminophenoxy) phenyl) propane 32.84 g (0.08 mol), trisulfite trioxide Put 49.65 g of phenyl (0.16 mol), 17.8 g of lithium chloride, 200 g of NMP, 150 g of pyridine, and
The reaction was carried out at 00 ° C for 3 hours to obtain a viscous solution. After reprecipitating this solution in methanol, the polymer was isolated and further reprecipitated in pure water 3 times to perform sufficient drying.

(Synthesis Example 2) Under the same reaction conditions as in Synthesis Example 1, a polyamide was synthesized using 13.78 g of 1,4-cyclohexanedicarboxylic acid as a dicarboxylic acid and 15.86 g of diaminodiphenylmethane as a diamine raw material.

(Synthesis Example 3) Under the same reaction conditions as in Synthesis Example 1, 13.78 g of 1,4-cyclohexanedicarboxylic acid as a dicarboxylic acid and 2,2-bis (4-(-aminophenoxy) phenyl) as a diamine raw material. A polyamide was synthesized using 41.48 g of hexafluoropropane.

(Synthesis Example 4) Under the same reaction conditions as in Synthesis Example 1, 13.29 g of terephthalic acid as a dicarboxylic acid and 15.86 g of diaminodiphenylmethane as a diamine raw material were used to synthesize a polyamide.

(Synthesis Example 5) Under the same reaction conditions as in Synthesis Example 1, 13.29 g of terephthalic acid as a dicarboxylic acid and 32.84 g of 2,2-bis (4- (4-aminophenoxy) phenyl) propane as a diamine raw material were used. The polyamide used was synthesized.

(Synthesis Example 6) Under the same reaction conditions as in Synthesis Example 1, 13.29 g of terephthalic acid as a dicarboxylic acid and 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane as a diamine raw material 41.48 Polyamide was synthesized using g.

(Synthesis Example 7) Under the same reaction conditions as in Synthesis Example 1, 4,4'-biphenyldicarboxylic acid 1 was obtained as a dicarboxylic acid.
9.38 g, 41.48 g of 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane as a diamine raw material
Was used to synthesize polyamide.

(Synthesis Example 8) 2,6-naphthalenedicarboxylic acid 1 as a dicarboxylic acid was prepared under the same reaction conditions as in Synthesis Example 1.
7.30 g, 41.48 g of 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoropropane as a diamine raw material
Was used to synthesize polyamide.

(Synthesis Example 9) Polymer obtained in Synthesis Example 1
10 g of DMSO was dissolved in 150 g of DMSO with stirring, and 2.9 g (0.044 mol) of powdery potassium hydroxide (85%) was added. Further, 5.3 g (0.044 mol) of 1-chlorohexane was added, and the reaction was carried out at 70 ° C for 6 hours. The reaction solution was reprecipitated in methanol to isolate the polymer, which was then dissolved in NMP and reprecipitated in pure water to purify the polymer.
It was confirmed by NMR measurement that hexyl groups were introduced into 90% of all amide nitrogens.

(Synthesis Examples 10 to 27) The polymers obtained in Synthesis Examples 1 to 8 were replaced with the protons of the amide nitrogen by the same procedure as in Synthesis Example 9. The halides (R ₃ -Cl or R ₃ -Br) used at that time are as shown in Table 1.

(Example 1) The polymer obtained in Synthesis Example 9 was dissolved in NMP to a concentration of 5 to 6%, and the pore size was adjusted.
After filtering with a 0.5 μm membrane filter, it was applied on the transparent electrode surface of the glass substrate with a transparent electrode by a spin coater and heated at 180 ° C. for 1 hour to form a coating film of about 800 Å. Subsequently, the coated surface was rubbed by a rubbing machine, two substrates were bonded together with a gap of 20 μm, and liquid crystal (ZLI-1132 manufactured by Merck & Co., Inc.) was injected to prepare a liquid crystal cell. When the orientation of the liquid crystal was evaluated by a microscope, it was uniform over the entire surface, and the pretilt angle was measured by the crystal rotation method. As a result, the pretilt angle was 8.4 degrees. In addition, 100 cells
The liquid crystal alignment and pretilt angle were measured after one month of treatment at 60 ° C and 60% RH, but there was no change compared to before treatment.

Examples 2 to 19 Liquid crystal cells were prepared in the same manner as in Example 1 using the polymers obtained in Synthesis Examples 10 to 27, and the alignment state and pretilt angle of the liquid crystal were measured. Show. In all cases, the cell is 100 ℃, 60% R
After treatment for 1 month under H condition, the liquid crystal orientation and pretilt angle were measured, but there was no change compared with before treatment.

Example 20 An NMP solution containing 10 parts by weight of the polymer obtained in Synthesis Example 9 and 90 parts by weight of the polymer obtained in Synthesis Example 1 was prepared, and a liquid crystal cell was prepared in the same manner as in Example 1. Table 2 shows the results of measurement of the liquid crystal alignment state and the pretilt angle. After the cell was treated at 100 ° C. and 60% RH for 1 month, the liquid crystal orientation and pretilt angle were measured, but there was no change compared with that before the treatment.

[0026]

[Table 1]

(Examples 21 to 23) As in Example 20, NMP solutions containing two kinds of polymers were prepared and the liquid crystal cell characteristics were evaluated. The polymers and their proportions used at that time and the evaluation results are shown in Table 2.

[0028]

[Table 2]

Comparative Examples 1 to 8 Liquid crystal cells were prepared in the same manner as in Example 1 using the polymers obtained in Synthesis Examples 1 to 8 and the alignment state and pretilt angle of the liquid crystal were measured. Show.

[0030]

[Table 3]

[0031]

INDUSTRIAL APPLICABILITY The liquid crystal alignment film of the present invention stably exhibits a high liquid crystal pretilt angle, and is therefore suitably used for a liquid crystal display device of TFT type, STN type or ferroelectric type.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

[0026]

[Table 1]

Claims (6)

[Claims] 1. An alignment film for a liquid crystal display device, comprising a polymer in which a repeating unit represented by the formula (1) is contained in a main chain. [Chemical 1] (Here, R ₁ and R ₂ are divalent organic groups, and R ₃ is a monovalent organic group) 2. In the formula (1), R ₁ is represented by the following 2
The alignment film for a liquid crystal display device according to claim 1, which is a kind of a valent organic group. [Chemical 2] 3. In the formula (1), R ₂ is 2 shown below.
The alignment film for a liquid crystal display device according to claim 1, which is a kind of a valent organic group. [Chemical 3] (Where R ₄ , R ₅ , R ₆ , R ₇ , R ₈ and R ₉ are hydrogen atoms,
8 is an alkyl group, an alkoxy group, or a trifluoromethyl group. ) 4. The alignment film for a liquid crystal display device according to claim 1, wherein R ₃ in the formula (1) is an organic group having 6 or more carbon atoms. 5. The alignment film for a liquid crystal display device according to claim 1, wherein R ₃ in the formula (1) is an organic group containing an aromatic ring having 6 or more carbon atoms or an aliphatic ring. 6. The alignment film for a liquid crystal display element according to claim 1, wherein R ₃ in the formula (1) is an organic group having 3 or more fluorine atoms and having 2 or more carbon atoms.