PHOSPHATE COMPOSITE COATED STEEL SHEET HAVING WHITE RUST RESISTANCE AND COATING CHARACTERISTIC

摘要

PROBLEM TO BE SOLVED: To provide a phosphate composite coated steel sheet having white rust resistance and coating characteristics equivalent to those of chromate sealed material.;SOLUTION: The phosphate composite coated steel sheet has a phosphate film on the surface of a galvanized steel sheet, and a surface-treated film consisting of a surface treatment composition containing (a) a water dispersion of a resin obtained by reacting a polyalkylene glycol modified epoxy resin obtained by reacting a polyalkylene glycol of the specified number average molecular weight, a bisphenol type epoxy resin, an active hydrogen-containing compound and a polyisocyanate compound, an epoxy group containing resin, and an active hydrogen containing compound consisting of a hydrazine derivative partly or totally having active hydrogen, (b) a silane coupling agent, and (c) at least one kind selected from phosphoric acid, a water-soluble phosphate and a hexafluoro metallic acid, is formed on an upper layer thereof.;COPYRIGHT: (C)2006,JPO&NCIPI