U.S. 8,632,895 B2
PPG has obtained a patent for a coated article comprised of a decorative metal substrate having a specular gloss greater than 400, with the proviso that the decorative metal substrate does not contain a pigmented coating thereon, a transparent cured coating thereon applied directly to the decorative metal substrate containing a resinous binder, 0.5 to 10 percent by weight based on total solids weight of the coating of a surface active agent and inorganic particles in which the concentration of particles in the exposed surface region of the cured coating is greater than the bulk region of the cured coating.
Source:
http://www.coatingsworld.com/issues/2014-12/view_patents/ppg-patents-coating-for-decorative-metals/
