Nihon Parkerizing Co., Ltd.

Yoshihiko Nishizawa

Kazuhiko Mori

Mitsuru Nakamura

Masanobu Tanaka

A hydrophilic, photocatalytic, transparent and adhesive aqueous TiO.sub.2 ceramic paint comprises orthotitanic acid, Ti.sup.4+ ions and/or peroxotitanic acid and crystalline TiO.sub.2 colloidal particles with an average particle size of 0.001 to 0.2 .mu.m, and is produced by applying (a) semipermeable membrane dialysis, (b) semipermeable membrane electrodialysis or (c) ion-exchange treatment to an aqueous Ti salt solution to thereby hydrolyze and convert at least a portion of the Ti salt to the orthotitanic acid and the TiO.sub.2 colloidal particles and simultaneously to remove impurity ions from the aqueous solution, or by heating the Ti salt solution at 50.degree. to 100.degree. C. after or without mixing an alkali metal hydroxide or ammonia to the Ti salt solution, and then applying the treatment (a), (b) or (c) to the resultant solution, or by mixing an alkali metal hydroxide or ammonia to the heated Ti salt solution followed by collecting a resultant precipitate and dispersing the precipitate in water or an aqueous solution of a peroxide compound or complexing agent.

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Tokyo, Japan

Yoshihiko Nishizawa