JPS6310844B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a transparent insulating coating for liquid crystal cells, etc.
In particular, a transparent film used as a film to prevent alkali ion elution from the lower substrate of a liquid crystal cell, an insulating film that separates an electrode layer formed on a substrate from a liquid crystal layer, a liquid crystal alignment film in a TN type liquid crystal display device, etc. The present invention relates to a paste for forming a transparent insulating film for forming an insulating film. Conventionally, this type of transparent insulating film is a film mainly composed of SiO ₂ and has been formed by vacuum evaporation, dipping, or the like. However, the vacuum deposition method has poor productivity and tends to require large equipment. In addition, the dipping method has the disadvantage that a film is formed in unnecessary locations and cannot correspond to finer patterns. In order to overcome these drawbacks, attempts have been made to print a paste into a desired shape onto a substrate using screen printing and bake it to form a transparent insulating film, 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. Furthermore, when an In-Sn-based oxide film is used as the transparent electrode material used in liquid crystal cells, external light is reflected at the electrode part, and even when the display device is not lit, depending on the viewing angle, There was a drawback that the electrodes were visible. The present invention has been made for the purpose of solving the conventional drawbacks and providing an insulating coating that can be formed by screen printing, which is dense, has high coating strength, has good electrical insulation, and has a great effect of preventing electrode reflection of external light. It is something that The feature of the present invention is that an insulating film can be formed by dissolving a mixture of an organic titanium compound, an organic zirconium compound, and an organic silicon compound in an organic solvent, adding and mixing a viscous agent, making a paste, and using a screen printing method. be. In other words, the film properties are improved by adding TiO ₂ to SiO ₂ , which has the effect of preventing external light from reflecting on the electrode, and ZrO ₂ , which has the effect of improving paste film formation and printability. This is because we measured the In order to be able to form a transparent insulating film by screen printing, the titanium compound, silicon compound, and zirconium compound must be stably dissolved in an organic solvent with a high boiling point (180° or higher), and the paste must be baked. It must completely become an oxide at a temperature of 450 to 700°C, and organic titanium compounds such as tetraoctylene glycol titanate (TOG) and organic silicones such as vinyltris(2-methoxyethoxy)silane (V-5000) This includes organic zirconium compounds such as zirconium tetraacetylacetonate (Zr(acac) ₄ ). The organic solvent required for paste preparation is a mixture of these organometallic compounds, which has poor reactivity.
The boiling point must be 180 to 350℃, and high-boiling point alcohols such as benzyl alcohol, dipropylene glycol, and 2-ethylhexanol, high-boiling point esters such as benzyl acetate and carbitol acetate, and high-boiling point ethers such as butyl cellosolve are required. , etc. can be applied, and two or more types of solvents may be used in combination. The viscosity agent must also have good solubility in the organic solvent and be completely thermally decomposed at the firing temperature of 450 to 700°C. As long as this condition is met,
Cellulose-based viscosity agents such as ethylcellulose and nitrocellulose can be used. The insulating coating obtained by applying the paste of the present invention onto an insulating substrate such as a glass substrate by screen printing and baking it is dense, has high coating strength, has good electrical insulation, and has a high effect of preventing electrode reflection of external light. It was hot. The present invention will be explained in more detail based on the above embodiments. Examples Tetraoctylene glycol titanate (TOG) is used as an organic titanium compound, vinyltris(2-methoxyethoxy)silane (V-5000) is used as an organic silicon compound, and tetraacetylacetonate zirconium (Zr(acac) is used as an organic zirconium compound. ₄ ), pastes were prepared with the following compositions by changing the mixing ratio of these organometallic compounds. Metal part (TOG + V-5000 + Zr (acac) ₄ ) 5wt% Solvent part (butyl cellosolve) 83wt% Viscous agent (ethyl cellulose) 12wt% In addition, as the metal part, organic silicon compound V-
A paste was prepared using only 5000 and used as a comparative example. Add the paste you created to 250 meters of stainless steel,
A screen plate with a resist thickness of 10 μm was used to print on a soda glass insulating substrate, pre-dried at 150° C. for 15 minutes, and baked at 500° C. for 30 minutes to form a film. Table 1 shows the results of comparing the characteristics of these films.

[Table] ×: Bad ○: Good
The paste of the present invention has good film forming properties, and also has a first
As can be seen from the table, the resulting coating has good adhesion strength, good insulation properties, and is silvery white and transparent.
It has a great effect of preventing electrode reflection of external light and is suitable as a transparent insulating film for liquid crystal display devices.

Claims (1)

[Claims] 1. A paste for forming a transparent insulating film obtained by dissolving a mixture of an organic titanium compound to which oxygen is directly bonded, an organic silicon compound, and an organic zirconium compound in an organic solvent, and further adding and mixing a viscosity agent.