Kao patents pigments

U.S. 8,153,163 B2
Kao Corporation has been granted a process for producing a pearl pigment comprised of adding an aqueous solution of a colored metal oxide precursor to an aqueous dispersion of a flaky powder so that the amount of metal ion is 5×10−4 to 12×10−4 mol/min per 100 g of the flaky powder; adding an alkaline solution to the mixed solution so that the pH of the mixed solution is adjusted to 5 to 8; separating the solid from the mixed solution; baking the separated solid at 500 to 1000° C to obtain a pearl pigment; suspending the obtained pearl pigment in water; adding an aqueous solution of a colorless metal or colorless metal oxide precursor to the suspension; adding an alkaline solution to the mixed solution so that the pH of the mixed solution is adjusted to 5 to 8; separating the solid from the mixed solution; and baking the separated solid at 500 to 1000° C; or adding an aqueous solution of a colored metal oxide precursor to an aqueous dispersion of a flaky powder so that the amount of metal ion is 5×10−4 to 12×10−4 mol/min per 100 g of the flaky powder; adding an alkaline solution to the mixed solution so that the pH of the mixed solution is adjusted to 5 to 8; separating the obtained solid from the mixed solution; adding an aqueous solution of a colorless metal or colorless metal oxide precursor to a dispersion of the solid; separating the obtained solid from the mixed solution; and baking the separated solid at 500 to 1000° C.