| 摘要 |
PROBLEM TO BE SOLVED: To obtain the subject new fine particles high in stability, not having a bluish white color, easily being finely pulverizable and high in transparency by using titanium dioxide, etc., as a core substance and covering surface thereof with titanium dioxide, etc. SOLUTION: The composite metal oxide fine particles having <=0.5μm particle diameter, consists of (A) titanium dioxide, an iron oxide or a mixture of the iron oxide and titanium dioxide as a core of which surface is covered with titanium dioxide and further covered with (B) metal oxides consisting of Mg and Ca of which amount is 2-20wt.% based on the component (B) and in which ratio of Mg to Ca is 0.2-5 in molar ratio in the component (B). Further, is order to obtain the particles, (C) an aqueous titanium tetrachloride solution is heated while agitating for thermally hydrolyzing the chloride to prepare a titanium hydroxide colloid, using a neutralizing hydrolysis method of simultaneously dripping the colloidal component, the component (C) and an aqueous alkali solution for sticking the titanium oxide hydrate to obtain the suspended liquid of the hydrate, preparing an aqueous solution containing Mg ion and Ca ion and an aqueous solution of an alkali metal hydroxide or an alkali metal carbonic acid salt, and simultaneously adding the solutions to the suspended liquid. |
