JP2000075274A - Insulation film coating liquid composition and liquid crystal display device provided with the insulation film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liq. crystal display device having excellent quality without inter-substrates short circuit and enabling to obtain a dense insulation film with low temp. backing by incorporating peroxy-titanium in an insulation film coating liq. compsn. forming an insulation film on a transparent electrode. SOLUTION: In an insulation film coating liq. compsn. coated on a transparent electrode substrate and forming the insulation film on the transparent electrode, peroxy-titanium is incorporated. The peroxy-titanium is a polymeric compd. of a peroxo-titanic acid having a peroxo-linkage. This peroxy-titanium is obtained by adding hydrogen peroxide to titanium hydroxide and at ambient temp. or heating at a temp. of <=90 deg.C or the like. Thus, since the dense insulation film is obtained with low temp. baking by using the insulation film coating liq. contg. peroxy-titanium, the liq. crystal display device of excellent quality without an inter-substrates short circuit is obtained and it is pref. especially for a color liq. crystal display device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating film coating liquid composition and a liquid crystal display device having the insulating film, and more particularly, to forming an insulating film on a transparent electrode of a liquid crystal display device. In particular, the present invention relates to an insulating film coating liquid composition suitable for a color liquid crystal display device, which can be fired at low temperature.

[0002]

2. Description of the Related Art A liquid crystal display element has a basic structure.
A pair of transparent electrode substrates on which transparent electrodes are formed is bonded via a peripheral sealing material, and a predetermined liquid crystal is sealed in the cell. In this case, insulation between the opposing transparent electrodes is ensured. For this purpose, an insulating film is formed on the transparent electrode.

In the case of forming this insulating film, a so-called sol-gel coating solution has been widely used. The composition of this coating solution is a metal alkoxide and a hydrolyzate solution thereof, and as the metal, silicon, titanium, zirconium and the like are mainly selected. Of these, titanium is the most suitable.

[0004] The main reason for this is that titania obtained by firing alkoxytitanium has a high dielectric constant and a small decrease in driving voltage. Not only that, titania has a high refractive index of light, and ITO (Indium) is a transparent electrode.
This is because it is possible to minimize the so-called “bone appearance” phenomenon, which is similar to the refractive index of Tin Oxide (Tin Oxide) and the pixel contour looks thin when not lit.

However, titanium alkoxide has a high decomposition temperature and cannot be converted to titanium oxide unless fired at a high temperature of 400 ° C. or higher. However, when the transparent electrode substrate is heated to 400 ° C. or higher, the resistivity of the transparent electrode made of ITO increases. Thus, by irradiating the titanium alkoxide with ultraviolet rays to promote its decomposition and then firing, it has become possible to fire at a temperature of about 300 ° C.

[0006]

SUMMARY OF THE INVENTION However, 300
Even at ℃, the firing temperature may still be too high. This is the case, for example, when a color filter is attached to a transparent electrode substrate.

That is, the color filter has a heat resistant temperature of 2
Since the temperature is 50 ° C. or lower, it is difficult to form a good film even by the above-described ultraviolet irradiation method. Even when the firing temperature is about 300 ° C., the ITO
Has a tendency to increase slightly, so that a thicker ITO film is required to obtain the same conductivity.

[0008]

In order to solve the above-mentioned problems, the present invention relates to an insulating film coating liquid composition which is applied to a transparent electrode substrate and forms an insulating film on the transparent electrode. Is included.

In this case, it is preferable that the titanium oxide contains another kind of metal element other than titanium, and that the titanium oxide has an alternate bond with the other kind of metal oxide.

Further, the present invention has a transparent electrode, and a pair of transparent electrode substrates having an insulating film formed on the transparent electrode are bonded together via a peripheral sealing material, and a predetermined liquid crystal is sealed in the cell. In the liquid crystal display device, the insulating film is formed of an insulating film coating liquid composition containing titanium peroxide.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, titanium peroxide is a polymer of peroxotitanic acid having a peroxo bond. This titanium peroxide is obtained by adding hydrogen peroxide to titanium hydroxide and heating it at room temperature or at 90 ° C. or lower.

Titanium hydroxide is produced by a method of hydrolyzing an inorganic titanium compound such as titanium tetrachloride or titanium dioxide or an organic titanium compound such as titanium alkoxide. Next, hydrogen peroxide is added thereto, and the mixture is stirred and heated to obtain titanium peroxide. In addition, titanium peroxide, titanium tetrachloride, dititanium sulfate,
It can also be obtained by directly reacting aqueous hydrogen peroxide with titanium alkoxide.

In order to apply the insulating film coating liquid composition to an insulating film of a liquid crystal display element, a film obtained by mixing with a silicon compound, a zirconium compound or the like and firing the mixture is used to minimize the so-called bone appearance. It is preferable to optimize the refractive index.

The silicon compound and zirconium compound include silicon hydroxide (silicic acid), zirconium hydroxide (zirconic acid), alkoxides and halides of silicon and zirconium, and hydrolyzates thereof.
And mixtures thereof. The mixing ratio of titanium and another metal is appropriately determined according to the refractive index of the film obtained by firing.

Incidentally, it is known that titanium oxide has a photocatalytic action. That is, when light in a certain wavelength range is irradiated, an organic substance in contact with titanium oxide may be oxidized and decomposed, and therefore, when applied to a liquid crystal display device, a display defect may occur due to exposure to light. There is.

To prevent this, Ti—O—Ti
Reduce the homo bond of the hetero bond Ti-OM (M is T
Alternate bonding that increases the number of metals other than i) is effective. The homo bond can be basically reduced by uniformly mixing a Ti compound as a starting material with another metal starting material in advance and then preparing a liquid.

This insulating film coating liquid composition is printed as a solution of a high boiling point, high viscosity polyhydric alcohol or a derivative thereof on a transparent electrode substrate by an offset flexographic printing method or the like.

The drying temperature for the main purpose of removing the solvent after printing is usually in the range of about 50 to 150 ° C. The calcination is a step performed for converting titanium peroxide to titanium oxide and for converting other metal compounds such as silicon to metal oxide.
The range is from 0 to 300 ° C, especially from 200 to 250 ° C.

[0019]

EXAMPLES Example 1 100 ml of a 50% titanium tetrachloride solution (manufactured by Sumitomo Chemicals) was diluted 70-fold with pure water. 2.5% aqueous ammonia was added to this solution to cause a reaction to have a pH of 2, and after standing, the supernatant was discarded. The remaining gel of Ti (OH) ₄ orthotitanate was repeatedly washed with water and purified.

This gel is suspended again in pure water and TiO ₂
To a slurry having a concentration of 2% by weight, 35% aqueous hydrogen peroxide was separately added and stirred at 5 ° C. for 10 hours, followed by stirring at room temperature for 7 days to obtain yellow transparent titanium peroxide. And
Silica sol “Snowtex EG-ST (trade name)” (SiO ₂ solid content: 20%, ethylene glycol solution, manufactured by Nissan Chemical Industries, Ltd.) was calcined with TiO ₂ :
SiO ₂ was mixed at a weight ratio of 1: 1 to prepare an inorganic insulating film coating solution.

Separately from this, a pair of transparent electrode substrates (mother substrates with a plurality of faces) formed by forming transparent electrodes made of ITO in a predetermined pattern on a glass substrate are prepared. The insulating film coating liquid was printed.
Next, each of the transparent electrode substrates was dried at 100 ° C. for 10 minutes, and then heated and baked at 250 ° C. for 30 minutes to obtain about 500 °
To obtain an insulating film of titanium oxide-silicon oxide.

Thereafter, a polyimide-based alignment film was formed according to a conventional method, and a rubbing alignment treatment was performed. Then, an in-plane spacer was scattered, and two transparent electrode substrates were bonded together through a peripheral sealing material and pressed to produce a liquid crystal display cell. After injecting liquid crystal into this cell under vacuum, each liquid crystal display cell was cut into individual cells to complete a liquid crystal display element. When this liquid crystal display element was turned on, a display with no short-circuit defect between the substrates was obtained.

Example 2 A color liquid crystal display device was obtained in the same manner as in Example 1 except that a transparent electrode substrate with a color filter was used as the transparent electrode substrate. When this color liquid crystal display element was turned on, a display free from short-circuit defects between the substrates was obtained as in Example 1.

[0024]

As described above, according to the present invention,
By using the insulating film coating solution containing titanium peroxide, the following effects can be obtained.

Since a dense insulating film can be obtained by sintering at a low temperature, a high-quality liquid crystal display element having no short circuit between substrates can be obtained, which is particularly suitable for a color liquid crystal display element. Since the insulating film is curable at a low temperature, both the equipment cost and the running cost can be reduced. Due to the strong adhesion to the substrate, which is a feature of titanium peroxide, a highly reliable insulating film can be obtained.

Claims (3)

[Claims] 1. An insulating film coating liquid composition applied to a transparent electrode substrate and forming an insulating film on the transparent electrode, comprising titanium peroxide. 2. The composition for coating an insulating film according to claim 1, wherein the composition further contains a metal element other than titanium, and the titanium oxide has an alternate bond with the oxide of another metal. 3. A liquid crystal comprising a pair of transparent electrode substrates having a transparent electrode and having an insulating film formed on the transparent electrode via a peripheral sealing material, and enclosing a predetermined liquid crystal in the cell. 2. A liquid crystal display device according to claim 1, wherein said insulating film is formed of an insulating film coating liquid composition containing titanium peroxide.