RUST-PREVENTIVE COATING AGENT AND RUST-PREVENTIVE TREATMENT

摘要

PROBLEM TO BE SOLVED: To obtain an inexpensive rust-preventive coating agent free of chromium having better anticorrosion that a chromium-containing rust-preventive agent and to provide a method of rust-preventive treatment using the same. SOLUTION: A rust-preventive coating agent contains 0.2-50 g of a thiocarbonyl group-containing compound and 0.1-5 g of phosphate ion in 1 liter of a composition comprising an aqueous resin and water as major components. Further, the rust-preventive coating agent contains 10-500 g of water dispersible silica. A method of rust-preventive treatment is to coat zinc-coated or non-zinc- coated steel with the rust-preventive coating agent.