Patent ID: 8268203

Claim:
A method for producing microcrystalline titanium dioxide in the rutile form having a crystal size below 15 nm by an aqueous process, the method comprising: a) treating a titanium dioxide starting material with a base to give an alkaline pH value to obtain a first intermediate precipitate; b) adding a silicon containing compound to the first intermediate precipitate having an alkaline pH, to obtain a second intermediate precipitate, wherein the silicon containing compound is added in an amount to give a final product with a content of silicon, calculated as SiO 2 , ranging between 0.5% and 10% by weight of TiO 2 ; c) treating the second intermediate precipitate with hydrochloric acid adjusted to a final concentration ranging between 15 and 65 g/l, to obtain a precipitate of rutile TiO 2 in an acidic pH, and d) neutralizing the rutile TiO 2 precipitate obtained in step c) to a pH between 4 and 6.