JPH02181117A - Production of liquid crystal panel - Google Patents

Abstract

PURPOSE:To completely suppress the elution of impurities from a liquid crystal cell substrate into a liquid crystal compsn. by using a specific silicon-contg. treating liquid, coating the surface of glass substrates with this liquid and subjecting the coating to a heating calcination treatment, thereby forming transparent insulating films which prevent the elution of the impurities to a liquid crystal layer. CONSTITUTION:The treating liquid prepd. by adding the element of phosphorus in the form of inorg. acid at a ratio of 1 to 10% of SiO2 to an org. soln. of silicon is used and after the surface of the glass substrates 1 are coated with this treating liquid, the coating is subjected to the heating calcination treatment. The transparent insulating films 4 which prevent the elution of the impurities to the liquid crystal layer are formed at 500 to 3,000Angstrom thickness. The org. soln. of the silicon refers to the orthoalkoxysilane the chemical formula of which is expressed generally by Si(OR)4 (R=alkyl group). The substrates for the liquid crystal panel which can completely suppress the elution of the impurities from the glass substrates 1 to the liquid crystal layer is obtd. in this way. The elution of the impurities from the liquid crystal panel substrates to the liquid crystal compsn. is thus completely suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention mainly relates to a method of manufacturing a glass substrate used in a field-effect liquid crystal panel.

[Prior art] A cell for a field-effect liquid crystal display panel is manufactured by the process shown in Fig. 1 (liquid crystal molecules are oriented) and then applied with an electric field to make the molecules almost parallel to the electric field. The display is made possible by placing polarizing plates above and below this cell. In this case, since the liquid crystal has a high resistance, almost no current flows, resulting in low power consumption. Furthermore, since the current flowing through the liquid crystal is small, there is almost no deterioration of the liquid crystal, and deterioration of the transparent electrodes can also be suppressed, making it possible to create a display panel with a very long life overall. However, impurities may be mixed into ordinary, sufficiently purified liquid crystals from the containers containing the liquid crystals or when the liquid crystals are sealed in cells. Furthermore, if the panel is operated for a long period of time, impurities in the transparent electrode may dissolve in the form of ions.

For this reason, the resistance value of the liquid crystal is low (which causes problems such as increased power consumption and deterioration of the liquid crystal, making it difficult to achieve long life and high reliability).

Conventionally, countermeasures as shown in FIG. 2 have been taken to address the above-mentioned problems. This countermeasure is to apply Si to the surface of the transparent electrode, which has been patterned in advance, by sputtering, vacuum evaporation, CVD, etc.
The O□ film is overcoated to prevent impurities in the transparent electrode from being eluted as ions, or to prevent deterioration of the transparent electrode due to the inevitable flow of current. However, coating processing methods such as sputter evaporation, vacuum evaporation, and CVD are not suitable for mass production, and they also require skilled process management or require a huge investment to acquire equipment, which can slow down the panel manufacturing process. It has become difficult to invest in

In order to avoid the above drawbacks of the vapor deposition method, the following improved techniques have also been proposed. That is, JP-A-52-13
Publication No. 0344 discloses that a solution containing organic silicon as a solute and ethanol as a solvent is applied and fired.
It does not contain 1% to 10% of the amount added to 2, and can simply prevent peeling of the insulating film and the occurrence of cracks. Moreover, a simple SiO□ film can be formed.

Next, JP-A-50-131549 discloses that metals such as PPb and Cd are added in the form of organic or inorganic compounds when forming an insulating film using an organic solution of silicon. Not only is the amount not determined, but the purpose of forming the insulating film is to stabilize the electrode alignment process by rubbing or to extend the life of the electrode. Others include JP-A-1975-
No. 131548 discloses that P and Pb are added to an organic solution of silicon.
Although it is disclosed that organic or inorganic compounds such as Cd are mixed in, the amount is not indicated and the purpose of mixing is
This lowers the heat treatment temperature.

[Problems to be Solved by the Invention] Conventionally known techniques have the problem of not being able to suppress impurities eluted from the liquid crystal cell substrate into the liquid crystal composition. Furthermore, the method of forming an insulating film using vapor deposition technology significantly increases the cost, making it difficult to manufacture the film on an industrial scale.

The present invention aims to solve the above-mentioned problems and provide a manufacturing method that can completely suppress the elution of impurities from a liquid crystal cell substrate into a liquid crystal composition and can be manufactured at low cost.

[Means for Solving the Problems] The method for manufacturing a liquid crystal panel of the present invention utilizes the electrical and optical properties of liquid crystal by enclosing a liquid crystal composition in a twisted orientation in a glass cell formed by vertically opposing transparent electrodes. In the manufacturing method of a liquid crystal display panel that displays images, the surfaces of the cell substrates facing each other are coated with a silicon organic solution (general formula: Si (OR) 4.R;
Using a treatment solution prepared by adding the phosphorus element in the form of an inorganic acid at a ratio of 1% to 10% relative to SiO3 to the alkyl group, the film is coated with a film containing SiO , the coated film has a thickness of 500 to 3000, and the treatment liquid is applied by a brush coating spinner shake-off method, a spraying method, a dipping constant velocity pulling method, or an off-sera 1-printing method. It is something to do.

[Implementation example 1] The present invention will be explained in detail below.

Organic solutions of silicon are orthoalkoxysilanes whose chemical formula is generally represented by Si (OR)-(R=alkyl group).

This substance is mixed with alcohol, methyl acetate, ethyl acetate, acetone, xylene, hydrochloric acid, sulfuric acid, acetic acid, formic vinegar, etc. as a solvent and used as a processing solution for thorough cleaning such as alkaline cleaning, acid cleaning, and pure water cleaning. It is applied to a glass substrate by any of the following methods: brush coating, spinner spin-off method, spraying method, immersion uniform speed pulling method, offset printing method, etc., and pre-baking is performed at a temperature of approximately 150'C to 200°C. This results in a slightly stronger film. Further, by firing at a high temperature of 400° C. or higher, a SiO2 film having a high effect of preventing impurity elution (hereinafter referred to as high quality) is obtained. A liquid crystal display panel assembled using this treated glass substrate can have a quality that is almost the same as or higher than that obtained by conventional treatment. In addition, in order to improve the quality of the pure SiO□ film obtained by the above-mentioned treatment method, a treatment solution is prepared by adding phosphorus element in the form of an inorganic acid in an appropriate proportion to the treatment solution. After applying a treatment solution to a glass substrate for a panel using any one of the above-mentioned methods, pre-baking and high-temperature baking are performed to obtain a SiO□ film to which the above-mentioned substance is added. A liquid crystal display panel in which a panel cell is assembled using this treated glass substrate can have a longer lifespan than a panel treated with a pure SiO□ film overcoat.

This is because a high quality film was obtained by adding the above substance to the SiO□ film. The addition amount ratio is SiO2
1% to 10% is preferable, and the effect will be diminished if it is more or less than that. In particular, if it exceeds 10%, there is a disadvantage that the substance will be eluted into the liquid crystal composition, resulting in disordered alignment. If i-1 is less than 1%, the amount of the substance added will be too small and the result will be close to the conventional result.

As described above, according to the present invention, additives can be added extremely easily compared to conventional SiO□ coating methods (e.g., sputter deposition, vacuum deposition, etc.), and the ratio of additives can be freely adjusted. It is possible to use Con1 Hero. Regarding the film thickness, the thicker the film, the better the long life, but the best range is between 500 and 3000 people. In the method of the present invention, once the conditions for applying the glass treatment liquid are determined, pre-firing and high-temperature firing can be performed in an electric furnace, and detailed process control is not required. There is no need for large capital investment as only a furnace or belt furnace is available, mass production is far greater than conventional methods, and overall rationalization has been made possible.

Next, the present invention will be specifically explained with reference to Examples.

The table below shows a comparison of the characteristics of the conventional silicon coated with organic oxide and fired and the phosphorus-added silicon of the present invention.

* Film thickness: 1000 people The solution was diluted to about 20% using ethanol and formic acid as a solvent to prepare a treatment solution. This treatment solution was applied onto a glass substrate patterned with transparent electrodes using a spinner, pre-baked at 150°C for 30 minutes, and further fired at 500°C for 3 hours. The liquid crystal display panel assembled using this glass substrate had a long lifespan that was approximately equal to or longer than that of a liquid crystal display panel formed using a conventional method.

[Effect of the invention 1] In the silicon organic solution of the present invention, elemental phosphorus is added in the form of an inorganic acid in an amount of 1% to 10% based on 51o2.
S]02+ additive-containing film was coated using a treatment solution prepared by adding at a ratio of 500 to 3000, and the coating method for the treatment solution was a hair-shaving spinner shake-off method, a spraying method, etc. Spraying method, dipping method, etc.
Because the printing method was used, it was possible to form an extremely high-quality and uniform film, completely suppressing the elution of impurities from the liquid crystal panel substrate into the liquid crystal composition, which could not be obtained using conventional methods. We were able to achieve the extraordinary effect of being able to inexpensively manufacture a liquid crystal panel that has a long life and is highly reliable.

[Brief explanation of the drawing]

FIG. 1 shows a sectional view of a conventional liquid crystal display panel. FIG. 2 shows a cross-sectional view of a liquid crystal display panel overcoated with a SiO2 film. Glass substrate NESA (transparent electrode) Liquid crystal composition SiO3 film with phosphorus added Polarizer Reflector plate Figure 2 Procedural amendment (voluntary) Indication of procedural amendment case Name of Heisei invention ρ/--? g,) 39'D Patent application filed on October 30, 1999 (10) Relationship with the case concerning a person amending the manufacturing method of a substrate for a liquid crystal panel Applicant: 2-4-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo (236) Seiko Epson Corporation Representative Director Tsuneya Nakamura

Claims (1)

[Claims] A method for manufacturing a liquid crystal display panel in which a liquid crystal composition is sealed in a twisted orientation in a glass cell formed by vertically facing transparent electrodes, and display is performed using the electrical and optical properties of the liquid crystal, wherein the cells are vertically facing each other. The surface of the cell substrate
Silicon organic solution {general formula: Si (
OR)_4, R: alkyl group}, using a treatment liquid prepared by adding the phosphorus element in the form of an inorganic acid at a ratio of 1% to 10% relative to SiO_2, SiO_2+ additive-containing coated with a film, and the coated film thickness is 500 to 3
000 Å, and the method for applying the treatment liquid is a brush coating spinner shake-off method, a spraying method, a dipping constant velocity pulling method, or an offset printing method.