PROCESS FOR PRODUCING COATED TIO2 PIGMENT USING COOXIDATION TO PROVIDE HYDROUS OXIDE COATINGS

摘要

The present invention provides a process for producing titanium dioxide (TiO2) pigment having a coating comprising silica and a second oxide selected from the group consisting of oxides of boron, phosphorus, magnesium, niobium, germanium, and mixtures thereof, comprising the steps of (a) reacting titanium tetrachloride (TiCl4) in the vapor phase with an aluminum compound and an oxygen-containing gas in a reactor at a temperature in the range of about 900 ~C to about 1600 ~C to provide a gaseous suspension comprising TiO2 particles, (b) contacting the gaseous suspension comprising the TiO2 particles with a silicon halide and an oxide precursor of boron, phosphorus, magnesium, niobium, germanium, and mixtures thereof, and (c) cooling the gaseous suspension to produce TiO2 pigment having a coating comprising silica and a second oxide.