JPH0995627A - Coating agent for forming metallic oxide thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject coating agent, comprising a polyhydric alcohol derivative of acetic acid as a solvent, capable of being readily coated, having practically desirable transparency and film thickness as a plasma display panel and forming a metallic oxide thin film according to a coating and thermal decomposition method. SOLUTION: This coating agent for forming a metallic oxide thin film comprises (A) a metallic salt of an alkaline earth metal and/or a rare earth metal with an organic acid, (B) a polyhydric alcohol derivative of acetic acid as a solvent (e.g. ethylene glycol monomethyl ether acetate) and (C) an additive comprising an organic substance. Furthermore, a metallic salt of Mg, Ba or Sr alone or a mixture of two or more thereof with the organic acid is preferably used with one or more metallic salts of Ca or a rare earth metal with the organic acids in combination as the component (A).

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a coating agent for forming a metal oxide thin film (hereinafter referred to as a coating agent) for forming a transparent dielectric protective film of a color plasma display panel by a coating pyrolysis method. Is.

[0002]

2. Description of the Related Art Conventionally, in an AC type plasma display panel (hereinafter referred to as PDP), protection of discharge electrodes,
In order to reduce the discharge start voltage and the discharge sustaining voltage, the electrodes are covered with a dielectric protective film made of an alkaline earth metal oxide.

Since the dielectric protective film of the full-color AC type surface discharge reflection type PDP is formed on the front glass, it is necessary to have particularly excellent transparency and electric characteristics. Therefore, the protective film is formed by the vapor deposition method, but it is expensive and requires complicated equipment, and the productivity is poor, so that there is an economical problem.

Therefore, there is no need for expensive and complicated equipment,
Moreover, there is a coating pyrolysis method as a method of forming a dielectric protective film in a simple process, and a specific example is a paste for forming a transparent film containing an alkaline earth metal compound soluble in an organic solvent (Japanese Patent Laid-Open No. SHO11-96, 58-135155),
A method for forming a dielectric protective layer (Japanese Patent Laid-Open No. Hei 6-162920), in which an organic compound containing an alkaline earth metal is applied to a dielectric and pyrolyzed to form a protective layer made of a metal oxide, and Mg or the like is applied to the dielectric layer. PDP coated with a metal alkoxide and thermally decomposed to cover a metal oxide protective film (Japanese Patent Laid-Open No. 6-2203).
72), alkali metal oxide particles, Al, S
A dielectric protective agent composed of a metal organic compound such as i, Ti, and Zr (JP-A-6-31667), a cathode of an AC type PDP, and a PDP in which a dielectric layer is covered with a metal oxide protective film (JP-A-6-31970). 7-14516) has been proposed.

[0005]

However, in the above-mentioned prior art, organic acid metal salt of alkaline earth metal,
Alternatively, when a metal alkoxide is used as a dielectric protective film precursor, it is possible to form a metal oxide thin film,
The thickness of the formed uniform and transparent film is 0.3 μm or less, and the film has poor adhesion to the dielectric. Moreover, the film thickness is set to 0.
When the thickness is 3 μm or more, a non-uniform and opaque film is formed, which is a practical problem.

An object of the present invention is to provide a coating agent containing a metal salt of an organometallic acid which forms a metal oxide thin film on a dielectric by a coating pyrolysis method, and a solvent which dissolves it and an additive consisting of an organic substance. Is easy to apply in PDP
It is an object of the present invention to provide a coating agent capable of forming a dielectric protective film, which has transparency and a film thickness which are practically desirable as the panel characteristics.

[0007]

In order to achieve the object of the present invention, when a polyhydric alcohol acetic acid derivative is used together with another solvent as a solvent for dissolving an organic acid salt of an alkaline earth metal and / or a rare earth metal, It is easy to apply by a method such as screen printing, spin coating, dipping, or spraying, and has a transparency and a film thickness that are practically desirable as panel properties of PDP by coating and drying and baking at 350 to 600 ° C. They have found that a dielectric protective film can be formed.

That is, the present invention is a coating agent for forming a metal oxide thin film containing an organic acid metal salt of an alkaline earth metal and / or a rare earth metal, a solvent, and an additive, which is a polyvalent solvent. It is a coating agent for forming a metal oxide thin film which forms a metal oxide thin film by a coating pyrolysis method, which comprises an alcohol acetic acid derivative.

According to the present invention, the organic acid metal salt, the solvent and the additive are each an organic substance, and these organic components are vaporized or thermally decomposed when the coating agent is applied, dried or baked to be put into the atmosphere. Dissipate. Therefore, the coating agent is decomposed into a metal and an organic component by coating and drying and baking, and the subsequent oxidation by heating forms a transparent metal oxide thin film having a high light transmittance.

The organic acid metal salt of an alkaline earth metal and / or a rare earth metal in the present invention is not limited to these solvents, but includes, for example, xylene, toluene, isopropyl alcohol, methyl isobutyl ketone, butyl acetate, diethylene glycol monobutyl ether, Solvents such as mineral spirits, cyclohexane, cyclohexanone can be dissolved alone or in combination, and the solution is combined with a thickener or a diluting solvent to form a coating agent that is easy to apply. 350-6
Even if baked at 00 ° C. for 1 to 30 minutes, a metal oxide thin film having good adhesion to the dielectric cannot be formed.

However, although it has not been theoretically clarified at present, the polyhydric alcohol acetic acid derivative of the present invention, for example, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate is used. , Ethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether acetate, ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol methyl ether acetoate, propylene glycol monoethyl ether acetoate, etc. in combination with other solvent Alternatively, when used alone, it is possible to form a uniform and transparent thin film having good adhesion to the dielectric. There is no limitation on how to use those solvents, and the organic acid metal salt may be simply mixed in a necessary amount in the preparation process or the preparation process of the coating agent.

In the present invention, one kind or two or more kinds of organic acid metal salts may be mixed and used, and in particular, one kind or two or more kinds of organic acid metal salts of Mg, Ba and Sr and Ca or rare earth metal. When one or more kinds of the organic acid metal salts are mixed and used, the physical strength of the metal oxide thin film mainly containing Mg, Ba, and Sr can be increased and the adhesion to the dielectric can be improved. I can.

The type of the organic acid forming the organic acid metal salt used in the coating agent of the present invention is not particularly limited as long as the formed organic acid metal salt can be dissolved in an organic solvent. For example, capron. Acid, caprylic acid, capric acid, octylic acid, secanoic acid, neodecanoic acid, neoheptanoic acid, neononanoic acid, N-heptanoic acid, naphthenic acid, tall oil fatty acid, etc. are preferably used alone or in combination of two or more kinds. . However, it is also possible to use a mixture of an organic acid having 6 or less carbon atoms, such as acetic acid or propionic acid, mixed with one having 7 or more carbon atoms. In addition, it is difficult to use a metal salt having an average carbon number of 6 or less as a starting material because the metal salt has poor solubility in a solvent, but it is used in a range in which it is soluble in another organic acid metal salt. It doesn't matter.

The solvent used in the present invention is diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether acetate, monoacetic acid. In addition to polyhydric alcohol acetic acid derivatives such as ethylene glycol, diethylene glycol monoacetate, glycerol monoacetate, propylene glycol methyl ether acetoate, propylene glycol monoethyl ether acetoate, etc. There is no particular limitation as long as it does, xylene, toluene, isopropyl alcohol, methyl isobutyl ketone, Butyl, diethylene glycol monobutyl ether, it is preferably used in combination as a solvent plurality of such mineral spirits.

As the organic additive used in the present invention, it is desirable to use ethyl cellulose, nitrocellulose, acrylic resin or the like as a thickener.

When the coating agent of the present invention is used as a paste for screen printing, a thickening agent such as ethyl cellulose, nitrocellulose, or acrylic resin is added to a solution of a metal salt of an organic acid in a necessary amount and dissolved. It is necessary to adjust the viscosity suitable for printing with a solvent such as diethylene glycol monobutyl ether, terpineol, and Texanol. When applying a spin coater or spray coating,
It is possible to use the screen printing paste diluted with a solvent, but it is not necessary to use a thickener, and it is sufficient to simply dilute the organic acid metal salt with the solvent. Further, an antifoaming agent or a leveling agent can be used as necessary.

However, whichever coating method is used, if the total metal content in the coating agent is high, it is difficult to coat thinly and uniformly, so that a desired transparent and uniform metal oxide thin film is formed. Becomes difficult. On the other hand, if the total metal content in the coating agent is low, a uniform thin film can be formed, but 0.4-
The coating pyrolysis must be repeated several times to obtain a film thickness of 1.3 μm. Therefore, the total metal content in the coating agent needs to be 4.0% by weight or less, preferably 0.5 to 2.0% by weight, by adjusting the amounts of the solvent and the thickener.

The method for preparing the coating agent for forming a metal oxide thin film of the present invention is not particularly limited, and a solution prepared by previously dissolving a thickener in a solvent is added to an organic acid metal salt solution and dissolved.
It is preferable to adjust the viscosity with a diluting solvent.

[0019]

【Example】

(Example 1) A Mg octylate solution having a Mg content of 2% by weight was diluted with a solvent shown in Table 1 by a weight ratio of 2 times, and the solution was cast on a slide glass (25 mm x 75 x 2) and then coated at room temperature. The state after drying for 30 minutes and the state after baking at 450 ° C. for 5 minutes were visually observed. As a result, No. 1 using an acetic acid derivative of a polyhydric alcohol as a solvent. 12 to 18
The product formed a transparent film having a thickness of 0.2 to 0.7 μm. No. No. 21 was in good condition after drying,
A uniform film was not formed after firing. Others did not form a uniform dry film.

[0020]

[Table 1]

Example 2 The metal contents of the organic acid salts of alkaline earth metals and rare earth metals shown in Table 2 were adjusted to 2% by weight with respective solvents,
A sample solution was prepared by adjusting the metal content to 1% by weight with a solvent in which diethylene glycol monobutyl ether acetate and xylene were mixed at a ratio of 8: 2 (weight ratio). The solution was cast on a slide glass, dried at 70 ° C. for 5 minutes, and then baked at 400 ° C. for 2 minutes. As a result, as shown in Table 2, it was possible to form a transparent thin film having good adhesion to glass.

[0022]

[Table 2]

Comparative Example No. 2 in Table 2 Each of 1 to 8 whose metal content was adjusted to 1% by weight with each diluting solvent was coated and dried under the same conditions, but a uniform film was not formed in the stage before firing.

Example 3 The same organic acid metal salt as in Example 2 was mixed at the mixing ratio shown in Table 3 with the metal content adjusted to 2% by weight with each solvent. The solution was further diluted by a factor of 2 (weight ratio) with a solvent in which diethylene glycol monobutyl ether acetate and xylene were mixed in a ratio of 8: 2 (weight ratio) to prepare a sample solution, which was applied and baked under the same conditions as in Example 2, The state of the formed film was examined. The results are as shown in Table 3. Nos. 2 to 10 formed a film having good adhesion to glass, but Mg octylate alone was liable to be scratched and had slightly poor adhesion to glass.

[0025]

[Table 3]

(Example 4) A coating agent was prepared at the compounding ratio shown in Table 4, and air spray coating was carried out.
After drying for 5 minutes, baking at 420 ° C. for 5 minutes, and after cooling, the light transmittance and film thickness were examined. As a result, a transparent thin film having a light transmittance of 85 to 95% and a film thickness of 0.1 to 1.3 μm was formed. did.

[0027]

[Table 4]

[0028]

The transparent MgO protective film of the dielectric of the surface discharge reflection type color PDP is conventionally formed by the vapor deposition method, but the productivity is poor and there is an economical problem. However, the coating material for forming a metal oxide thin film of the present invention is screen-printed or spray-coated on the dielectric of PDP, and after drying, 350 to 6
By baking at 00 ° C for 1 to 30 minutes, the film thickness becomes 0.1
It became possible to form a transparent metal oxide thin film of ˜1.3 μm. As a result, a significant economic effect can be expected.

Claims (2)

[Claims] 1. A coating agent for forming a metal oxide thin film, which comprises an organic acid metal salt of an alkaline earth metal and / or a rare earth metal, a solvent, and an additive, and a polyhydric alcohol acetic acid derivative as a solvent. A coating agent for forming a metal oxide thin film, which comprises a metal oxide thin film formed by a coating pyrolysis method. 2. An organic acid metal salt of Mg, Ba, Sr alone or a mixture of two or more kinds of organic acid metal salts, and one or more kinds of organic acid metal salts of Ca or rare earth metals are used in combination. The coating agent for forming a metal oxide thin film according to claim 1.