merck patents
silver pigments
Patent No. U.S. 7,344,590 B2
Merck Patent has been awarded a patent for a silver pigment, consisting of a transparent, platelet-shaped substrate, which is an SiO2 platelet, Al2O3 platelet, a polymer platelet, a single crystal or a glass platelet, having a refractive index <1.9, and an average thickness of individual platelets within a standard deviation of <20%, and on the substrate a coating of TiO2 and optionally an outer protective layer, the pigment having a silver interference color, whereby the pigment exhibits color travel.