Patent ID: 8663376
Filing Date: 2014-03-04
Classification: C08G,C09D,C23C,Y10T

Abstract:
1. A surface treatment solution for autodeposition coating treatment of a metallic material, comprising an aqueous solution comprising: at least one tannin; at least one crosslinking agent having a crosslinking group capable of thermosetting reaction with a phenolic hydroxyl group and/or a phenolic nucleus; ferric ions; soluble elemental fluorine comprising hydrofluoric acid; at least one fluoride selected from the group consisting of cerium fluoride, yttrium fluoride, aluminum fluoride and strontium fluoride; said at least one fluoride having low solubility in an aqueous solution of hydrofluoric acid, and being present in an amount in the surface treatment solution such that said at least one fluoride is mostly present in a form of solid particles; and an oxidizing agent; wherein a solids mass concentration ratio of the tannin to the crosslinking agent ranges from 1:1 to 1:10, a molar concentration of the soluble elemental fluorine is at least 3 times molar concentration of the ferric ions, and the solution has a pH of from 2.3 to 6.