JP2841348B2 - Electro-optic electrode substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Effect of the Invention] (Industrial application field) The present invention relates to an electro-optical electrode substrate excellent in heat resistance, orientation, and durability.

(Prior Art) In recent years, applications of display devices utilizing optical anisotropy of liquid crystal have been advanced in various fields. The main method used for this display is the use of a dynamic scattering phenomenon in which a nematic liquid crystal compound having negative dielectric anisotropy scatters light when applied to an electric field (referred to as a DS type device). There is also an FE device in which the optical rotation is changed and used for display by aligning a nematic liquid crystal compound having a positive dielectric anisotropy. DS-type devices do not necessarily require uniformity of the initial alignment of the liquid crystal compound due to the principle of operation, but FE-type devices control or rearrange the initial compounding of the liquid crystal compound by an electric field. Since the change in properties is used, uniformity of the initial alignment of the liquid crystal compound is particularly important.

Conventionally, as a means for obtaining uniformity of the initial alignment of a liquid crystal compound, a method of rubbing one side of light with an electrode substrate with a cloth or the like is known. However, this method has the drawbacks that the alignment of liquid crystal compound molecules is partially different, the alignment uniformity is not sufficient, and the alignment is lost in a short time. As a method of improving this disadvantage, there is a method of rubbing the electrode substrate against one side by using a certain kind of surfactant in combination.However, although the uniformity of the orientation is improved to some extent, the surfactant used in combination has a heat resistance. However, there is a disadvantage that this leads to deterioration of the liquid crystal compound. Further, there is a disadvantage that if the electric field is continuously applied, the surfactant is decomposed and deteriorated by the electric field to destroy the orientation.

Further, a conventional method of rubbing an electrode substrate coated with a condensed polyimino resin in one direction has been used. This case has the advantage of being excellent in the alignment effect and heat resistance to the liquid crystal compound, but has the disadvantage that it cannot be applied to a flexible electrode substrate because the curing temperature of the polyimide resin is high and the resin is hard.

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above-mentioned drawbacks, and has excellent heat resistance, orientation, and durability, and can be used for a flexible electrode substrate. It is intended to provide an electrode substrate.

[Constitution of the Invention] (Means for Solving the Problems) The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that the above object can be achieved by using a novel polyimide resin. The present invention has been completed.

That is, the present invention provides: (A) (a) a compound having an imide group and an epoxy group represented by the following general formula and (b) phenylenediacrylic acid on a part or all of the surface of a substrate having a transparent conductive film. A polyimide resin, (Where R is (B) An electro-optical electrode substrate comprising a coating film of a heat-resistant photosensitive composition containing a sensitizer and a photoinitiator, wherein the coating film is subjected to an orientation treatment.

 Hereinafter, the present invention will be described in detail.

As the transparent conductive film used in the present invention, for example, indium oxide, tin oxide, a mixture of tin oxide and indium oxide, a mixture of tin oxide and antimony oxide, titanium oxide,
Metallic thin films of metal oxides such as rhodium oxide and platinum oxide are exemplified. Glass, ceramic, plastic film and the like are used as a substrate on which the transparent conductive film is coated, and a vapor deposition method, a sputtering method,
The transparent conductive film is coated by a CVD method, a spray method, or the like.

As the heat-resistant photosensitive composition used in the present invention, a composition comprising (A) a polyimide resin, (B) a sensitizer and a photoinitiator is used. The (A) polyimide resin used here is obtained by subjecting (a) a compound having an imide group and an epoxy group and (b) phenylenediacrylic acid to an addition reaction. (A) As the compound having an imide group and an epoxy group, a compound represented by the following general formula is used.

(Where R is (B) Phenylenediacrylic acid is represented by the following structural formula.

In this addition reaction, the above-mentioned compound having an imide group and an epoxy group and approximately equimolar amounts of phenylenediacrylic acid having a photopolymerizable unsaturated group are mixed in an organic solvent at a temperature of 150 to 200 ° C. for 3 to 12 minutes. The addition reaction is carried out for a time, and a polyimide is obtained. At this time, it is preferable to use a basic reaction catalyst such as a tertiary amine. If necessary in this addition reaction, a solvent can be used. Examples of the solvent in this case include N-methyl-2-pyrrolidone, dimethylacetamide, dimethylformamide, dioxane, diglyme, and the like, and these can be used alone or as a mixture of two or more.

The (B) sensitizer and photoinitiator used in the present invention include:
Benzoin alkyl ethers such as benzoin, benzoin ethyl ether, benzoin isopropyl ether, benzoin phenyl ether, benzoin thioethers, benzophenone, acetophenone, 2-ethyl-
Anthraquinone, decyl chloride, thioxanthones and the like can be mentioned, and these can be used alone or in combination of two or more.

The heat-resistant photosensitive composition used in the present invention contains a polyimide resin, a sensitizer and a photoinitiator, but, as far as it does not violate the purpose of the present invention, and if necessary, further incorporates a heat polymerization inhibitor and the like. be able to.

Examples of such a thermal polymerization inhibitor include p-methoxyphenol, hydroquinone, 2,6-di-tert-butyl-4-methylphenol, methyl ether hydroquinone, benzoate, benzoquinone, and 4-hydroxymethyl-2,6.
-Di-t-butylphenol and the like, and these can be used alone or in combination of two or more. The mixing ratio of the thermal polymerization inhibitor is preferably in the range of 0.05 to 2.0 parts by weight based on 100 parts by weight of the heat-resistant photosensitive composition.

The heat-resistant photosensitive composition is soluble in an organic solvent.
It is used as a solution (photosensitive resin liquid) dissolved at a ratio of 4040% by weight, preferably 15-30% by weight. Examples of the organic solvent include N, N-dimethylsulfoxide, N, N-dimethylformamide, N, N-diethylformamide, N, N-dimethylacetamide, N, N-diethylacetamide, N-methyl-2-pyrrolidone, Examples thereof include diglyme, hexamethylenephosphamide, γ-butyllactone, cyclohexane, and the like, and these can be used alone or as a mixture of two or more.

In order to form a protective coating film on an electrode substrate using a photosensitive resin solution, it is usually formed as follows. The photosensitive resin solution was dissolved in a solvent to form a 0.01 to 25% by weight resin solution, which was applied to the electrode substrate by a brush coating method, an immersion method, a printing method such as offset or stamping, a spin coating method, a spray method, or the like. Later, 60
The solvent is dried by heat treatment at a temperature of 100100 ° C., and thereafter, a cured coating film is formed by irradiating ultraviolet rays such as a hydraulic mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp and a xenon lamp. Next, the coating film surface is rubbed and oriented in a certain direction with a cloth or the like, so that an electro-optical electrode substrate can be manufactured.

An electro-optical display device can be manufactured by sealing and sealing a nematic liquid crystal compound having a positive dielectric anisotropy between a pair of alignment-treated surfaces of the electro-optical electrode substrate manufactured as described above in a known manner. . Such an electrode substrate can be effectively used for various electro-optical devices such as a calculator, a wristwatch, a clock, a counting display, and a personal computer.

(Function) The electrode substrate for electro-optics of the present invention could be made excellent in heat resistance, orientation and durability by using a novel polyimide resin.

The present invention provides a reaction between an imide substrate represented by the aforementioned general formula, a compound having an epoxy group, and a phenylenediacrylic acid having a photopolymerizable unsaturated group, to form a ring-closed imide group and a photocurable group in the molecule. By using a polyimide resin having the formula (1), heat resistance is imparted since a combined use of a surfactant is not required, and excellent orientation can be obtained. In addition, since the film can be photocured in a short time after being dried by heating at a low temperature, the film can be applied to a flexible substrate without becoming hard.

(Examples) Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples, “parts” means “parts by weight”.

Example 1 After passing dry nitrogen through a three-necked flask and replacing the inside of the flask with nitrogen, a compound 27.5 having an imide group and an epoxy group derived from benzophenonetetracarboxylic anhydride was used.
0.03 part of triethylamine was added to 0 part and 6.97 parts of phenylenediacrylic acid. After heating the flask to a temperature of 150 ° C., the temperature was raised to 200 ° C. at a heating rate of 20 ° C./one hour, and the reaction was stirred at 200 ° C. for 4 hours while suppressing the heat generation due to the reaction. After the reaction was completed, diglyme was added and the mixture was cooled, and the mixture was poured into a mixed solution of methanol and water to precipitate a polyimide resin. The precipitate was dried to obtain 34.0 g of a brown polyimide resin powder. 20 parts of this polyimide resin powder was dissolved in 80 parts of diglyme, and 2 parts of benzoin isopropyl ether was added and blended as a photoinitiator to prepare a photosensitive resin liquid.

Example 2 After the atmosphere in the flask was replaced with nitrogen by passing dry nitrogen through a three-necked flask, 23.93 parts of a compound having an imide group and an epoxy group derived from pyrometic anhydride and 6.97 parts of phenylenediacrylic acid were added to 0.03 part of triethylamine. added. After heating the inside of the flask to a temperature of 150 ° C., the temperature was raised to 200 ° C. at a heating rate of 20 ° C./one hour, and the reaction was stirred at 200 ° C. for 4 hours while suppressing the heat generated by the reaction. After the reaction was completed, diglyme was added and the mixture was cooled, and the mixture was poured into a mixed solution of methanol and water to precipitate a polyimide resin.
The precipitate was dried to obtain 29.83 g of a brown polyimide resin powder. 20 parts of this polyimide resin powder was dissolved in 80 parts of diglyme, and 2 parts of benzoin isopropyl ether was added and blended as a photoinitiator to prepare a photosensitive resin liquid.

Example 3 After the atmosphere in the flask was replaced with nitrogen by passing dry nitrogen through a three-necked flask, 26.88 parts of a compound having an imide group and an epoxy group derived from 4,4'-oxydiphthalic anhydride and 6.97 parts of phenylenediacrylic acid were added. , Triethylamine
0.03 parts were added. After heating the flask to a temperature of 150 ° C., the temperature was raised to 200 ° C. at a heating rate of 20 ° C./one hour, and the reaction was stirred at 200 ° C. for 4 hours while suppressing the heat generation due to the reaction. After the completion of the reaction, diglyme was added and cooled, and then added to a mixed solution of methanol and water to precipitate a polyimide resin. The precipitate was dried to obtain 33.0 g of a brown polyimide resin powder. 20 parts of this polyimide resin powder was dissolved in 80 parts of diglyme, and 2 parts of benzoin isopropyl ether was added and blended as a photoinitiator to prepare a photosensitive resin liquid.

The electrode substrate, which was formed by etching a Nesa glass having a transparent conductive film of indium oxide in a pattern and then washed by a usual method, was immersed in the photosensitive resin solution manufactured in Examples 1 to 3. After being lifted from the dipping and dried at a temperature of 100 ° C. for 30 minutes, it was photosensitive-cured by a 250 W high-pressure mercury lamp to form a 1000 A thick heat-resistant photosensitive composition coating film on the electrode substrate. The pair of electrode substrates on which the coating film was formed was rubbed in one direction with a cloth and subjected to an orientation treatment to produce an electro-optical electrode substrate. Thereafter, the cells are assembled so that the friction directions are orthogonal to each other, and a nematic liquid crystal compound having a positive dielectric anisotropy is encapsulated.
Further, a polarizing film was attached to both outer surfaces of the cell such that the polarization directions of the polarizing films were respectively parallel to the friction directions of the adjacent substrates, thereby producing a display device. These display devices were tested for moisture resistance (60 ° C x 95% RH x 500H) and heat resistance (80 ° C x 500H). In any of the tests, no destruction of the orientation was observed, and uniformity of the orientation was observed. It was good and excellent in durability, and the effect of the present invention was confirmed.

Comparative Example 1 Nesa glass having a transparent conductive film of indium oxide was washed, applied by immersing it in a 0.5% aqueous solution of polyoxyethylene nonylphenyl ether as an alignment treatment agent, then dried by heating under vacuum, and the coated surface was unidirectionally covered with a cloth. Nesa glass that was subjected to orientation treatment by friction was produced. The pair of Nesa glasses thus obtained is assembled into a cell such that the friction directions are orthogonal to each other, a nematic liquid crystal compound having a positive dielectric anisotropy is sealed, and a polarizing film is further provided on both outer surfaces of the cell. Were bonded to each other so that the polarization directions were parallel to the friction direction of the adjacent substrates to produce a display device. In this display device, unevenness of light and dark orientation was observed in a display portion when an electrode was applied, and after 60 ° C. × 95% RH × 100 H, the orientation was destroyed and durability was poor.

Comparative Example 2 A display device was produced in the same manner as in Comparative Example 1, except that the alignment treatment was not performed and the Nesa glass surface was directly frictionally rubbed in one direction with a cloth. In this display device, there was light and dark alignment unevenness in the display portion when an electrode was applied, and after 50 ° C. × 3 H, the alignment began to be destroyed and completely destroyed two days later, resulting in poor heat resistance and durability.

[Effects of the Invention] As is clear from the above description, the electro-optical electrode substrate of the present invention is excellent in heat resistance, direction resistance, durability, and moisture resistance, and particularly, uniformity of initial alignment of the liquid crystal compound. It has a special advantage that it can be applied to a film substrate which is weak to heat, such as polyester, because the film is formed by photo-curing. Also, even if the temperature of the electrode substrate was increased, the alignment effect of the molecules of the liquid crystal compound was not affected, and the molecules of the liquid crystal compound in the cell could be stably present for a long period of time.

Claims (1)

(57) [Claims] 1. A method comprising: (A) (a) a compound having an imide group and an epoxy group represented by the following general formula and (b) phenylenediacrylic acid on a part or all of the surface of a substrate having a transparent conductive film. Polyimide resin that reacts, (Where R is (B) An electro-optical electrode substrate comprising: a coating film of a heat-resistant photosensitive composition containing (B) a sensitizer and a photoinitiator, wherein the coating film is subjected to an orientation treatment.