| 摘要 |
PROBLEM TO BE SOLVED: To obtain a zinc oxide powder which influences the stability of various products and is suppressed in various activity such as photocatalytic activity and solid acid properties by heating a zinc oxide powder to a specified temperature. SOLUTION: The zinc oxide powder used desirably have a mean particle diameter of 5nm to 100μm. Particularly, a microparticulate zinc oxide powder having a mean primary particle diameter in this range has high activity, and its activity is markedly influenced by heat treatment. The zinc oxide powders include powders of titanium oxide treated with zinc oxide and mica coated with zinc oxide as well as pure zinc oxide represented by ZnO. The heat treatment consists of heating to a temperature of 600-1,700 deg.C, desirably 800-1,200 deg.C. Although the heating time depends on the heating temperature, it is desirably 0.1-48hr, more desirably 1-12hr. This method is useful to suppress the photocatalytic activity and solid acid activity of the powder which are factors important in cosmetics.
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