Patent ID: 8916007
Filing Date: 2014-12-23
Classification: C08K,C09D,C23C

Abstract:
1. A composition for chemical conversion treatment comprising at least 0.1 g/L of a polyphenol and at least 1.5 g/L in chromium ion equivalent of an aqueous trivalent chromium compound, and having a pH of 6 or less, wherein a chemical conversion coating formed on a metallic surface of a member by contacting the metallic surface with the composition for chemical conversion treatment has a content of hexavalent chromium of 0.04 μg/cm 2 or less as measured by a method compliant with EN15205 after exposure to an environment having a temperature of 80 degrees C. and a relative humidity of 100% for 120 hours, wherein the polyphenol comprises at least one of the compounds selected from the group consisting of pyrogallol, 5-methylpyrogallol, 5-propylpyrogallol, pyrogallol-1,3-dimethylether, pyrogallol-1,3-diethylether, and 5-propylpyrogallol-1-methylether.