Patent ID: 6623555
Filing Date: 2003-09-23
Classification: A61K,A61Q,C01P,C09C

Abstract:
A method for making a composite pigment, comprising the steps of:(a) providing lime mink comprising calcium hydroxide suspended in an aqueous medium; (b) inducing a calcium carbonate precipitation reaction by introducing carbon dioxide into the lime milk effective to precipitate calcium carbonate as a reaction product of the calcium hydroxide and the carbon dioxide; (c) introducing a soluble silicate compound into the aqueous medium at a time when the calcium carbonate precipitation reaction in step (b) has progressed to within approximately 90% to 100% of completion; and (d) introducing carbon dioxide into the aqueous medium containing said soluble silicate compound and precipitated calcium carbonate for a period of time effective to precipitate an insoluble silicon compound onto said precipitated calcium carbonate to provide a composite pigment, wherein the aqueous reaction medium has a maximum temperature variation during the silicate precipitation period of less than 20Â° C. during said period of time.