Titanium dioxide pigment and method of preparation

A method of preparing a pigmentary composite comprising the steps of:

• (a) preparing an aqueous slurry comprising water and a particulate titanium dioxide base;
• (b) depositing a layer of a hydrous zirconium oxide precipitate on said titanium dioxide base;
• and
• (c) depositing a layer of a hydrous alumina precipitate on said layer of hydrous zirconium oxide precipitate, said hydrous alumina precipitate consisting essentially of boehmite alumina, pseudoboehmite alumina, or a combination thereof

A method of preparing a pigmentary composite consisting essentially of the steps of:

• (a) dispersing a particulate titanium dioxide base in water to form an aqueous titanium dioxide slurry;
• (b) adding a water soluble zirconium compound to said slurry which is hydrolyzable to form a hydrous zirconium oxide precipitate;
• (c) forming a layer consisting essentially of hydrous zirconium oxide on said titanium dioxide base by allowing said hydrous zirconium oxide precipitate to deposit on said titanium dioxide base while maintaining the pH of said slurry in the range of from about 7 to about 9;
• (d) after step (c), adding a water soluble aluminum compound to said slurry which is hydrolyzable to form a hydrous alumina precipitate;
• (e) forming a layer consisting essentially of hydrous alumina on said layer of hydrous zirconium oxide by allowing said hydrous alumina precipitate to deposit on said layer of hydrous zirconium oxide;
• (f) during steps (d) and (e), maintaining the pH of said slurry in the range of from about 7 to about 9 and the temperature of said slurry in the range of from about 115.degree. F. to about 122.degree. F.;
• and
• (g) recovering said pigmentary composite from said slurry.