Composite titania-calcined kaolin opacifying pigments and method for making and using same
AssigneeEngelhard Corporation
InventorSaad Nemeh
Life of this patent
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Abstract
Novel titania-calcined kaolin composite pigments wherein structuring and adhesion of titania and calcined kaolin particles is achieved by use of a cationic polyelectrolyte. Methods for compositing titania and calcined kaolin pigments which feature the presence of at least one polyanionic dispersant (such as sodium polyacrylate, sodium silicate, sodium condensed phosphate or mixtures thereof) in the pigment slurry into which cationic polyelectrolyte is introduced and the use of strongly alkaline pH (e.g., above 9).
Claims21
A composite opacifying pigment comprising particles of titania pigment and particles of calcined kaolin coflocculated and bound together in the form of coherent aggregates by an organic cationic polyelectrolyte.
A method for manufacturing a composite opacifying pigment which comprises:
- providing particles of titania pigment, providing particles of calcined kaolin pigment, mixing said particles together in the presence of water to form a slurry containing a physical admixture of said particles, introducing a water-soluble cationic polyelectrolyte in the presence of water either to said particles of titania pigment, said particles of calcined kaolin pigment or a physical admixture thereof, at a pH above 9 and in the presence of at least one anionic pigment dispersant, a sufficient amount of said cationic polyelectrolyte being added to coflocculate and bind together said particles of titania and said particles of calcined kaolin into unitary coherent particles, and recovering the coflocculated particles of titania pigment and calcined kaolin pigment, and, optionally adding additional anionic pigment dispersant to said coflocculated bulked particles.
Dependencies are inferred from the claim text.