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Abstract

A process produces fine particle titanium dioxide essentially transparent to visible light and essentially UV radiation absorbing. During preparation of the titanium dioxide product, tin dioxide with a particle size of 1 to 10 nm, and preferably 1 to 4 nm, is added, in an amount of 0.5 to 10 weight percent with respect to TiO.sub.2. The particle size of the titanium dioxide is specifically adjusted by the tin dioxide addition. Acicular particles are rounded by heat-treatment between 300.degree. and 800.degree. C., and preferably between 400.degree. and 600.degree. C. The particles can be post-treated to produce a coating of inorganic and/or organic substances. The fine particle titanium dioxide can be prepared by the decomposition of sodium titanate with hydrochloric acid or by suitable hydrolysis of a tetravalent titanium compound which leads to rutile formation. A currently preferred way of adding the tin dioxide is as a colloidal sol which is prepared by the reaction of tin tetrachloride with water at a maximum of 22.degree. C.

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