JPS6143723A - Paste for forming transparent insulating film - Google Patents

Abstract

PURPOSE:To improve a film forming characteristic, film strength, orientation to liquid crystal molecules, etc. by dissolving a mixture composed of an org. aluminum compd. and org. indium compd. into an org. solvent and adding and mixing a viscosity builder thereto. CONSTITUTION:A mixture composed of the org. aluminum compd. and org. indium compd. is dissolved in the org. solvent and further the viscosity builder is added thereto to prepare the paste. The paste is coated on a substrate by screen printing and is then baked by which a liquid crystal display device is obtd. The org. indium compd. includes indium alkoxide, indium acetyl acetonate, etc. and the org. aluminum compd. includes aluminum alkoxide, alminum acetyl acetonate, etc. The cellulosic viscosity builder such as ethyl cellulose or nitricellulose is adequate as the viscosity builder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transparent insulating coating for liquid crystal cells, etc., and particularly to an IE film for preventing alkali ion elution from a lower substrate of a liquid crystal cell, etc.
The present invention relates to a paste for forming a transparent insulating film, which is used as an insulating film that separates an electrode layer and a liquid crystal layer formed on a substrate, a liquid crystal alignment film in a TN type liquid crystal display device, and the like.

Conventionally, this type of transparent insulating film has generally been an inorganic film containing Sin as a main component or an organic polymer such as polyimide. The former is formed by a vacuum evaporation method, a dipping method, a spin coating method, etc., and the latter is formed by a dipping method, a spin coating method, etc. However, the vacuum evaporation method has poor productivity and tends to require large equipment, while the dipping method and spin coating method result in coatings being formed in unnecessary areas, and resulting in excessive 100% undesirable effects such as pattern knitting due to etching. He had a flaw that required Mu.

In order to overcome these drawbacks, attempts have been made to form a transparent insulating film by printing paste into a desired shape onto a substrate using screen printing and baking it, but the formed film is brittle and porous. In many cases, the properties of the film itself were inferior to those formed by vacuum evaporation or immersion methods.

The present invention has been made for the purpose of eliminating the above-mentioned drawbacks, and providing a transparent insulating film that has good electrical insulation, good transparency, high film strength, good orientation for liquid crystal molecules, and can be formed by screen printing. It is.

A feature of the present invention is that a mixture of an organic indium compound that becomes an In, O, -A403-based oxide upon firing and an organic aluminum compound is used as the main component of the paste for forming a transparent insulating film.

The characteristics required of a transparent insulating film used in a liquid crystal display device include high electrical insulation, uniform film formability, high adhesion strength to a glass substrate, and alignment force for liquid crystal molecules. Especially in field effect IjlTN liquid crystal display devices,
It is important to uniformly align liquid crystal molecules in a certain direction in order to improve the display effect. In! O,, A4
0. Transparent insulating coatings each having separate components are known, but each has the following drawbacks. In other words, a film containing In and O8 as a component has good orientation to the liquid crystal component and film formability, but is not good in electrical insulation because it is transparent to the extent that it is used as the main component of the pole.

Hereinafter, a film containing Alzos as a component has high film strength and good electrical insulation, but the liquid crystal molecules are oriented perpendicularly to the substrate and not parallel to the substrate. However, the transparent coating H formed by firing a paste obtained using certain compounds of indium and aluminum is uniform with good coating strength, has good electrical insulation properties, and has good orientation with respect to liquid crystal molecules. I got something good. That is, in the present invention,
By outlawing In2O2-Altos-based oxides as transparent insulating coating compositions, it is possible to create transparent insulating coatings that have good film formability, good film strength, good orientation to liquid crystal molecules, and good electrical insulation properties. Furthermore, a paste obtained by dissolving a mixture of an organic indium compound and a specific aluminum compound in a solvent and adding a viscosity agent is applied onto a substrate by screen printing. However, by firing, there is no need for large-scale manufacturing equipment, and there is an advantage that inexpensive devices such as liquid crystal display devices can be provided.

Examples of organic indium compounds applicable to the present invention include indium alkoxide and indium acetylacetonate.
) Specific aluminum compounds such as acac3 include aluminum alkoxide, aluminum acetylacetonate AA! (acac), etc.
Any material may be used as long as it is stably dissolved in a high boiling point organic solvent and completely becomes an oxide upon firing at 450 to 700°C. Next, the organic solvents necessary for making a paste include those that have poor reactivity and a boiling point of 180 to 350°C, such as organic indicum compounds and certain aluminum compounds; Robylene glycol,
High boiling point organic solvents such as high boiling point alcohols, high boiling point esters such as benzyl acetate and carpitol acetate, and high boiling point ethers such as butyl cellosolve can be used. As the viscosity agent, cellulose-based viscosity agents such as cellulose, ethyl cellulose, and nitrocellulose can be used as long as they have a good solubility in the above-mentioned solvent and are not completely thermally decomposed by firing at 450 to 700°C. is applicable.

Hereinafter, K will be explained in more detail based on examples of the present invention.

Example 1 Using Al(acac) as an organoaluminum compound, and using n(acac)3 as an organic indium compound,
The mixing ratio of these organometallic compounds was varied to create a paste with the following composition.

Metal part 3vt% (-X+Y')A
J(acac)I
7.1wt% dimethyl phthalate 17wt viscosity agent 115wt cellulose H80M 115wt Also, for comparison, all metal parts are AA! (acac)3 or In(acac)3
As a chisel, I made a paste. The prepared paste was printed on a soda glass substrate using a stainless steel 250 mesh screen plate with a resist thickness of 10 μm.
An initial film was formed by pre-drying at 150°C for 15 minutes and baking at 500°C for 30 minutes, and various film properties were compared. The first table of happiness is this result.

Table 1 From the first batter, A40s Int with a lot of A7tO and ingredients.
It can be seen that the broken 03-based compound film has good film formability, is dense, has a large coating strength, has good adhesion to the substrate, and has good electrical insulation, transparency, and orientation for liquid crystal molecules.

Example 2 In Example 1, nitrocellulose was used as the viscous material I, but in this example, ethyl cellulose N 200 was used to prepare a paste with the following composition.

Metal part 3wt% (=X+Y)Ar
(acac)3 Xwt%In(acac
c) I Ywt% solvent part 85
．． 5 wt% 2-ethylhexanol 51.3 w
t% benzyl alcohol 34.2 wt thickener 11.5 wt% ethyl cellulose
Using the paste prepared at 11.5 wt%,
AltO,-In,O obtained in the same manner as in Example 1
, we investigated the properties of membrane removal from the system, and found that the results were not much different from those obtained when nitrocellulose was used.

Claims (1)

[Claims] A paste for forming a transparent insulating film obtained by dissolving a mixture of an organic aluminum compound and an organic indium compound in an organic solvent, and further adding and mixing a viscosity agent.