JPH04124614A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To obtain the liquid crystal oriented film which is uniform and defect-free and has good orientation property without subjecting the film to a treatment, such as ribbing, by laminating the monomolecular film obtd. by developing an acid anhydride introduced with a hydrophobic group by an esterification reaction and a polyimide precursor obtd. by condensation polymn. of diamine on a water surface on a substrate formed with an electrode layer, then subjecting the film to such a heat treatment as to effect an imidization reaction. CONSTITUTION:The polyimide precursor material used for producing the monomolecular film is a material having high flatness or linearity. Particularly the materials expressed by the following formulas (1), (2) are more preferable. The long chain alkyl amine compd. having 8 to 25C univalent alighat. group has the effect of imparting a hydrophobic property to the polyimide precursor and forming a stable condensed film on the water surface and allows the accumulation of the monomolecular film on the substrate by an LB method. The imidizatioon treatment is executed by heating the substrate laminated with the LB film as the imidization treatment. The imidization treatment by heating is executed preferably under the flow of an inert gas at the temp. required in a liquid crystal assembly stage or above, or at the temp. below the temp. at which the LB film material is decomposed or below, more specifically 150 to 450 deg.C after the formation of the LB film. The imidization reaction is progressed by this heat treatment and even such low-molecular material as the materials mixed at the time of the film formation are removed. The chemical resistance and heat resistance of the LB film are improved as well.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The present invention relates to a liquid crystal element having a new liquid crystal alignment film. [0002]

[Conventional technology]

Conventional 5102.Flat displays using liquid crystals are becoming widely used in watches and televisions. AL
A liquid crystal display element is obtained by aligning the liquid crystal using an alignment film formed by an oblique vapor deposition method such as 1, or by applying a polyimide polymer resin on a substrate and rubbing it in a certain direction with a cloth or the like. There is. [0003]

[Problems to be solved by the invention]

However, since the oblique evaporation method is a vertical vacuum evaporation method that is very advantageous in giving a pre-tilt angle to the liquid crystal, it requires a high vacuum of about 10-5 torr, and the substrate must be tilted. Therefore, it has the disadvantage of poor mass productivity. [0004] The rubbing method also has the disadvantage that the generated dust and static electricity generated during rubbing have an adverse effect. [0005] In order to solve these problems of the conventional technology, the present invention provides a liquid crystal alignment film that is uniform, has very few defects, and has good alignment without rubbing, and is low-cost and highly mass-producible. The purpose is to obtain. Furthermore, it is also aimed at imparting chemical resistance and heat resistance to the liquid crystal alignment film. [0006]

[Means to solve the problem]

In order to solve the above problems, the present invention improves the flatness or linearity of the polyimide precursor material that forms a monomolecular film on the water surface, so that the monomolecular film can be easily flow-oriented when forming the LB peritoneum. The LB film was used as a liquid crystal alignment film. [0007]

[Effect]

According to the present invention, the structure described above has uniform, defect-free, and good orientation without any treatment such as rubbing.
A liquid crystal alignment film can be obtained at low cost and with high mass productivity. Furthermore, the liquid crystal alignment film obtained by the present invention also has good chemical resistance and heat resistance. [0008]

【Example】

Next, the present invention will be explained with reference to examples. The polyimide precursor material used for producing the monomolecular film of the present invention is a material with high planarity or linearity. In particular, materials expressed by the following formulas (1) and (2) are desirable. [0009]

[Chemical formula 16] In the formula, R1 is

[Chemical formula 17]

[Chemical formula 18] or

[Chemical formula 19] and R2 teeth,

[C20] or

[C21]

embedded image Furthermore, the acid anhydride moiety and diamine moiety described as R and R2 in the above formula (1) may be composed of a mixture of materials having high planarity or linearity. For example, the following copolymer materials are suitable. [0010]

[0011] R in formula (1) is a monovalent aliphatic group having 10 to 3 carbon atoms, which imparts hydrophobicity to the polyimide precursor and forms a stable condensed film on the water surface. bring about the effect of
The LB method makes it possible to accumulate a monolayer on a substrate. [0012] JP-A-4-124614 (If) Furthermore, one of the requirements of the present invention is that R3, which provides hydrophobicity, is in the para position as a carboxylic acid ester, which accounts for 40% of the total camic dianhydride. A carboxylic acid diester having R3 at the meta position may be mixed if the ratio is smaller. [0013]

[C24] In the formula, R4 is

[C25] or

[C26]

[C27] or

[C28] and R5 is

[C29] or

embedded image embedded image O Furthermore, the acid anhydride moiety and the dinamine moiety described as R and R5 in the above formula (2) may be composed of a mixture of materials having high planarity or linearity. For example, the following copolymer materials are suitable. [0014] o=O 0=O 0=0 ■=0 [0015] In formula (2), R6, R7, and R8 have 1 to 1 carbon atoms.
25 monovalent aliphatic group or hydrogen atom, R6
At least one of R7 and R8 has 8 or more carbon atoms.
25 monovalent aliphatic group. [0016] The long-chain alkylamine compound having a monovalent aliphatic group having 8 to 25 carbon atoms imparts hydrophobicity to the polyimide precursor, brings about the effect of forming a stable condensation film on the water surface, and LB
The method makes it possible to accumulate monolayers on a substrate. [0017] The long chain alkylamine compound having a hydrophobic group may be at the para position, meta position, or a mixture thereof. [0018] Further, the polyimide precursor of the present invention has a number average molecular weight of
It is desirable that it is between 2.000 and 300.000. When the number average molecular weight is out of the range of 2.000 to 300.000, there is a tendency that the strength of the LB film produced is too low or the viscosity is too high, making it difficult to produce the LB film. [0019] Although there are no particular limitations on the method for producing a monomolecular film, a method that causes flow orientation during accumulation is desirable, and the LB method (vertical dipping method) is one of the preferred embodiments. [0020] At this time, known L such as long chain fatty acids and long chain alcohols
A mixture of the B film material and the polymer LB film material previously proposed by us in JP-A-63-218728 may be used.

It is also a preferred embodiment of the present invention to subject the substrate to a surface treatment before depositing the monolayer. [0022] Another requirement of the present invention is to perform imidization treatment. As the imidization treatment, there is a method in which the substrate on which the LB film is laminated is immersed in an acid anhydride such as acetic anhydride, propionic anhydride, butyric anhydride, or dehydration ring closure by heating. As a result of our extensive studies, we have found that the method of performing imidization treatment by heating is more advantageous than the heat resistance and chemical resistance of the LB film. [0023] The imidization treatment by heating is preferably carried out under the flow of an inert gas at a temperature higher than the temperature used in the liquid crystal element assembly process after the LB film is formed and lower than the temperature at which the LB film material decomposes,
Specifically, 150°C to 450°C, more preferably 150°C
It is carried out at a temperature of 0.degree. C. to 250.degree. By this heat treatment, the imidization reaction progresses, low-molecular substances mixed during film formation are also removed, and the chemical resistance and heat resistance of the LB film are also improved. [0024] (Example 1) ITO was vacuum deposited to a thickness of 200 nm using a mask with a pattern formed on one side of a glass substrate. On the other hand, 2
, 3,6.7-Naphthalenetetracarboxylic dianhydride distearyl ester is used as an acid chloride, and a polyimide precursor of the following formula is obtained by reacting it with para-phenylenediamine. Langmuir on a glass substrate
Eleven layers were accumulated by the Projet method (LB method). Furthermore, the glass substrate on which the LB film was formed was heat-treated at 200° C. for 1 hour. By this heat treatment, the polyimide precursor becomes a polyimide represented by the following formula, and the LB film has very good chemical resistance and heat resistance. [0025] [0026] Two of the same treated glass substrates described above were prepared, and a cell was constructed such that the pulling directions of the two substrates during LB film formation were perpendicular to each other. The surface on which the electrode layer was formed was used as a sealing resin, and an acid anhydride-curing epoxy resin in which plastic beads with a diameter of 8 μm were dispersed was printed with a width of 1 mm on the entire circumference, leaving a length of 5 mm in the center of one side. Then, apply pressure with the transparent electrodes facing each other,
The adhesive was cured by heating at 140° C. for 3 hours. After adhesion, a nematic liquid crystal (manufactured by Merck & Co., Ltd.) is inserted through the opening under reduced pressure.
(trade name: ZLI-2701) was injected. After the injection, the opening was fixed with a commercially available acid anhydride-curable epoxy resin to seal the liquid crystal and complete a TN-type liquid crystal cell. By heating the completed liquid crystal cell to 100° C. and then gradually cooling it for initial alignment, a cell with a uniform, defect-free and good alignment state was obtained. [0027] (Examples 2 to 11) TN type liquid crystal cells were completed in the same manner as in Example 1 using various polyimide precursor materials shown in Tables 1 to 6.

[Table 1] [Table 21 [Table 41] [Table 61 (In Tables 1 to 6, R is stearyl group, A is N. N-dimethyl-n-hexadecylamine) [0028] Contrast was measured using static driving. did. The results are shown in Table 1. It can be seen that the liquid crystal element obtained in the molded example has electro-optical properties equivalent to those of the liquid crystal element obtained by the conventional rubbing method. [0029] Effects of the Invention 1 As explained above, according to the present invention, with the above-described structure, a product having uniform, defect-free and good orientation without any treatment such as rubbing, which is low-cost and highly mass-producible. A liquid crystal alignment film can be obtained. Furthermore, the liquid crystal alignment film obtained by the present invention also has good chemical resistance and heat resistance.

Claims (4)

[Claims] Claim 1: A polyimide obtained by condensation polymerization of the acid anhydride and the diamine into which a hydrophobic group has been introduced by an esterification reaction, using materials with high flatness or linearity as the acid dianhydride and diamine. A liquid crystal element comprising a thin film in which a monomolecular film obtained by spreading a precursor on a water surface is laminated in one or more layers on a substrate on which at least an electrode layer is formed, and then heat-treated to cause an imidization reaction. . [Claim 2] An amphiphilic polymer substance having a repeating unit represented by the following formula (1), [Chemical formula 1] ▲There are mathematical formulas, chemical formulas, tables, etc.▼(1) (In the formula, R^1 [Chemical Formula 2] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Or, [Chemical Formula 3] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Or, [Chemical Formula 4] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ , R^2 is [Chemical formula 5] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Or, [Chemical formula 6] ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Or, [Chemical formula 7] ▲There are mathematical formulas, chemical formulas, tables, etc. ▼ and R^3 is a monovalent aliphatic group having 12 to 30 carbon atoms.) The liquid crystal device according to claim 1, which is used as a thin film formed on an electrode layer. 3. A polyimide obtained by reacting a polyimide precursor obtained by condensation polymerization of a highly planar or linear material with a long-chain alkylamine compound having a hydrophobic group as an acid dianhydride and a diamine. A liquid crystal containing a thin film obtained by laminating one or more monomolecular films obtained by spreading a precursor derivative on a water surface on a substrate on which at least an electrode layer is formed, and then heat-treated to cause an imidization reaction. element. [Claim 4] An amphiphilic polymer substance having a repeating unit represented by the following formula (2), [Claim 8] ▲There are mathematical formulas, chemical formulas, tables, etc.▼(2) (In the formula, R^4 is , [Chemical Formula 9] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Or, [Chemical Formula 10] Or, [Chemical Formula 11] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Or, [Chemical Formula 12] ▲ Numerical formulas, chemical formulas, tables, etc. There is ▼ and R^5 is [Chemical formula 13] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Or, [Chemical formula 14] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ Or, [Chemical formula 15] ▲ Formulas, There are chemical formulas, tables, etc. ▼ where R^6, R^7, and R^8 have 1 to 25 carbon atoms.
is a monovalent aliphatic group or hydrogen atom, R^6,
At least one of R^7 and R^8 has 8 carbon atoms
~25 monovalent aliphatic group. ) The liquid crystal element according to claim 3, wherein the liquid crystal element is used as a thin film formed on an electrode layer.