Method for producing fine particles of metal oxide

Chemistry of inorganic compounds – Oxygen or compound thereof – Metal containing

Reexamination Certificate

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C423S608000, C423S612000, C423S617000, C423S618000, C423S624000, C502S349000, C502S350000, C502S353000, C502S355000

Reexamination Certificate

active

06328947

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for producing fine particles of metal oxide, and more specifically, relates to a method for fine particles of metal oxide with the feature of having narrower particle size distribution and moreover for the particles with a little of aggregation. Titanium dioxide (herein after as titanium oxide) is preferred as the metal oxide.
2. Related Background Art
In late years, in the field of fine particle forming such as ceramic, fine particles of metal oxide having narrower particle size distribution and only a little of aggregation thereof is desired as high dimension accuracy material capable of micro-working. Particularly, titanium oxide attracts attention as useful fine particle material in the field of photocatalyst, optical communication, cosmetics and so forth.
As a method for producing fine particles of metal oxide, a method for producing them by hydrolysis of metal alkoxide with organic solvent is proposed in, for example, the Japanese Patent Application Laid-Open Gazette No. Sho 61-266308 in which antimony is used as metal. A method for producing them by hydrolysis of organometal compound is proposed in the Japanese Patent Application Laid-Open Gazette No. Hei 1-230407. Various kinds of metals are listed in it.
Another method in which inorganic acid solution is added to the mixture of organic titanium compound and water-miscible organic solvent followed by hydrolysis thus producing rutile type titanium oxide is proposed (the Japanese Patent Application Laid-Open Gazette No. Hei 6-305730). However, there is a problem that the particles produced by these methods are apt to have wider particle size distribution and aggregate together.
SUMMARY OF THE INVENTION
This invention was done on the background of the above-mentioned technical problems of the prior arts, and an object of this invention is to provide a method, in which particle size is controlled easily, for producing fine particles of metal oxide, preferably titanium oxide, with the feature of having narrower particle size distribution and only a little of aggregation thereof. Another object of this invention is to provide the above described method in which where the metal oxide is titanium oxide, titanium oxide with desired crystal pattern can be produced by selection of solvent.
As a result of intensive efforts to achieve the above-mentioned purposes, the present inventors accomplished this invention described below.
This invention is a method for producing fine particles of metal oxide, the method comprising a step of hydrolyzing metal halide in the presence of organic solvent to obtain the fine particles of metal oxide.
In the above-mentioned method of this invention, it is preferred that the amount of the organic solvent is from about 200 to about 10,000 parts by volume to 100 parts by volume of water.
It is also preferred that the mean particle size of the fine particles of metal oxide is about 20 nm or less than 20 nm.
In the above-mentioned method of this invention, it is preferred that the metal halide is titanium tetrachloride and the metal oxide is titanium dioxide.
In this case, when the organic solvent may be hydrophilic and the titanium dioxide is anatase type.
Alternatively, when the organic solvent may be hydrophobic and titanium dioxide is rutile type.
According to this invention, fine particles of metal oxide with mean particle size of about 20 nm or less than 20 nm, narrower particle size distribution and only a little of aggregation thereof can be made.


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Barksdale, Jelks, Ph. D. Titanium. The Ronald Press: New York. Copyright 1949, p. 76-79.*
English abstract for JP 61-266308.
English abstract for JP 01-230407.
English abstract for JP 06-305730.

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