Ishihara Sangyo Kaisha, Ltd.

Masakazu Hattori

Akihito Sakai

Hideo Takahashi

Haruo Okuda

Hideo Futamata

Dendrite or asteroidal titanium dioxide micro-particles having a length of 0.2 to 0.5 .mu.m, a thickness of 0.05 to 0.1 .mu.m, and a specific surface area of 20 to 130 m.sup.2 /gram, are produced by treating hydrated titanium oxide particles with an alkali, mixing instantaneously the resulting reaction product with an amount of hydrochloric acid in a ratio of 1 to 4 mols of hydrochloric acid to one mol of the titanium oxide in the reaction product to effect a reaction, then aging under heat at 85.degree. C. or higher, and then drying or, if necessary, firing after the drying, and subsequently may be coated with at least one from oxides and hydrated oxides of elements selected from aluminum, silicon, titanium, zirconium, tin and antimony to improve the dispersibility and resistance to light of the particles, or may be coated with tin oxide containing antimony or indium oxide containing tin to make the particles electroconductive. These titanium dioxide micro-particles are useful for use in electroconductive paints, electroconductive resin compositions, paints and electroconductive paints for magnetic recording media, sunscreen cosmetics, UV screening paints and UV shielding plastic compositions and the like.

Dendrite or asteroidal titanium dioxide micro-particles and process for

Ultrafine iron-containing rutile type titanium dioxide particles useful for UV shielding cosmetics, pharmaceutical compositions and UV shielding paints are disclosed. They are rutile type crystalline titanium dioxide particles having an average single particle size of 0.01 to 0.1 .mu.m and containing an iron component at a concentration of 1 to 15% by weight as expressed as Fe based on the titanium dioxide in the crystalline structure. They can be produced by using a fine titania sol comprising rutile crystallites as basic particles, precipitating iron oxide or hydrated iron oxide onto the surfaces of the titania particles to effect coating, then firing and grinding.

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Yokkaichi, Japan

Masakazu Hattori