Titanium dioxide finishing process

Details Titanium dioxide finishing process Titanium dioxide finishing process

2007-07-24

2007-07-24

Green, Anthony J. (Department: 1755)

Compositions: coating or plastic

Materials or ingredients

Pigment, filler, or aggregate compositions, e.g., stone,...

C106S436000, C423S610000, C423S611000, C423S612000

Reexamination Certificate

active

11263702

ABSTRACT:
This disclosure relates to process for producing titanium dioxide (TiO2) pigments, comprising the following steps: a) oxidizing a mixture of titanium tetrahalide and a rutile forming agent, such as aluminum halide, present in the vapor phase and in the presence of a nucleant to form a gaseous suspension comprising titanium dioxide particles; b) passing the gaseous suspension to a cooling conduit; c) introducing scouring material into the cooling conduit; wherein the particles of the scouring material have a diameter in the range of about 0.25 mm to about 12.7 mm; d) separating the vapor phase to form a powder comprising the titanium dioxide particles and the scouring material; and e) simultaneously subjecting the powder to substantially uniform heating at a temperature of about 300° C. to about 600° C. and reducing the size of the titanium dioxide particles and the particles of the scouring material in the powder to a mean particle size of about 50 nm to about 1000 nm, whereby the titanium dioxide pigment has a chloride content of less than about 500 ppm. The so treated powder may have a residual free chlorine content of less than about 1 ppm.

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