Patent No. U.S. 7,485,365 B2
Eckart GmbH has been granted a patent for lustrous copper-based metal flakes that contain, in addition to 70-98% weight copper, at least one additional metallic alloy component comprised of 2% to up to 30% weight zinc and are produced via vacuum evaporating of the separate components and wherein each component of the alloy is evaporated separately, deposition of alloy metal films onto a carrier sheet, stripping of the films from the carrier sheet and subsequent comminuting of the films wherein the flakes have plane-parallel surfaces and a thickness of between 20 and 60 nm.