| 摘要 |
PURPOSE: A method for preventing nonchromium rust is provided which is improved in the rust-preventing property and the adhesion for re-coating. CONSTITUTION: The method comprises:washing a zinc-electroplated steel sheet with a solution containing one or more phosphor-containing compounds of 0.1-200 g/l, which are selected from the group consisting of phosphoric ion, condensed phosphoric ion, phitinic acid and phosphonic acid; and coating the surface with a rust-preventing coating agent comprising one or more sulfur-containing compounds of 0.1-20 g/l, which are selected from the group consisting of sulfate, sulfur powder, triazinethiol compound, thiocarbonyl-containing compound, thiosulfuric acid, thiosulfate, persulfuric acid, persulfate and sulfur oxide, a water-soluble resin, and water-dispersing silica of 10-500 g/l. The water-soluble resin is polyolefin-type resin, polyurethane-type resin, acryl-type resin, polycarbonate-type resin, epoxy-type resin, polyester-type resin, alkid-type resin, phenol-type resin and other thermosetting resins.
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