摘要:
The present invention provides methods of preparing a titanium dioxide pigment having improved gloss properties which involves heating an aqueous slurry of base titanium dioxide pigment to a temperature below about 75° C., coating the base titanium dioxide pigment with a silica compound at a temperature below about 75° C. to form a silica coated titanium dioxide pigment; and coating the silica coated titanium dioxide pigment with an alumina compound at a temperature below about 75° C. to form the titanium dioxide pigment having improved gloss.
摘要:
Titanium dioxide pigments having improved gloss and durability are disclosed. These pigments are prepared by continuous processes, where pH, temperature, and addition times of hydrous silica and alumina coatings are carefully controlled.
摘要:
The present invention provides a coated titanium dioxide pigment which includes a base titanium dioxide pigment; a first deposit of a phosphate compound contiguous with the base titanium dioxide pigment; a deposit of a silica or zirconia compound contiguous with the phosphate deposit; a second deposit of a phosphate compound contiguous with the silica or zirconia compound; and a deposit of an alumina compound contiguous with the second phosphate deposit. Titanium dioxide pigments of the present invention are easily dispersible, and display excellent durability and gloss. The present invention also provides processes for preparing coated titanium dioxide pigments which include the steps of: preparing an aqueous slurry of base titanium dioxide pigment, adding a first phosphate compound to the slurry to form a first phosphate coating, adding a silica or zirconia compound to the slurry to form a silica compound coating, adding a second phosphate compound to the slurry, and adding an alumina compound coating to the slurry to form an alumina compound coating, thereby forming the coated titanium dioxide pigment.