PURPOSE: To obtain the titanium dioxide capable of providing an inorganic coating excellent in long-term suspension stability, nonflammability, weathering resistance and stain resistance because of being chemically stable even in strong alkali solution by coating the surface of particles with SiO2 and Al2O3.
CONSTITUTION: This titanium dioxide consists of particles, having 0.2-0.3μm average particle diameter, whose surface is coated with Si02 and Al2O3. This titanium dioxide is obtained by suspending titanium dioxide powder having 0.2-0.3μm average particle diameter in water, adding a silicic acid salt such as sodium silicate to the suspension so as to gradually control pH to ≤6 at 40-100°C over 20-360min and precipitating silicon on the surface of titanium dioxide, successively adding an Al salt such as sodium aluminate, controlling pH and precipitating aluminum onto the surface of the titanium dioxide. Furthermore, as the titanium dioxide, a rutile type titanium dioxide is preferably used.
FUKUMOTO HIROSHI
TERABE ATSUKI
