Patent ID: 8475582

Claim:
A process for making a water dispersible titanium dioxide slurry comprising: (a) mixing dry titanium dioxide pigment with water to form a first mixture having a pigment concentration of from about 14 to 40 weight percent based on the weight of the first mixture then adjusting the pH of this first mixture to about 7 with aqueous sodium hydroxide; (b) heating the first mixture of step a) to a temperature of about 40 C to form a heated first mixture; (c) adding to the heated first mixture about 0.15 to 0.65 moles of a phosphoric acid per kilogram of dry titanium dioxide pigment and a sodium aluminate aqueous solution to form a second mixture comprising aluminum phosphate, wherein the phosphoric acid and the sodium aluminate aqueous solutions are added to the heated first mixture at a rate such that the pH of the second mixture is maintained at about 5 to 8; (d) curing the second mixture for about 10 to 30 minutes to form a cured mixture; (e) filtering the cured mixture and recovering, washing, drying, and fluid energy milling a treated titanium dioxide pigment consisting of a coating consisting of aluminum phosphate; (f) blending the treated titanium dioxide pigment consisting of a coating consisting of aluminum phosphate with water to form a third mixture; (g) adjusting the pH of the third mixture to form a slurry wherein the slurry comprises 70 to 80 percent by weight of the treated titanium dioxide pigment consisting of a coating consisting of aluminum phosphate based on the weight of the slurry.