| abstract |
(57) [Summary] [PROBLEMS] Suitable for metal, especially galvanized steel sheet, A rust-preventive coating agent that does not contain chromium, can impart excellent corrosion resistance to painted metal, and has excellent topcoat adhesion and storage stability. SOLUTION: One liter of a rust-preventive coating agent containing an aqueous polyurethane resin and an aqueous polyolefin resin in a resin solid content ratio of 3: 7 to 7: 3, in an amount of 10 to 500 g. Water-dispersible silica, 0.02 to 20 g of a silane coupling agent and / or a hydrolyzed condensate thereof, 0.2 to 50 g per liter of the aqueous resin composition (a) obtained by reacting at a temperature of at least 0 ° C. and at most the boiling point of the resin composition. A thiocarbonyl group-containing compound, and 0.1 to 5 g of phosphate ions. |