| abstract |
An object of the present invention is to provide a rust prevention method capable of reducing the rust prevention treatment cost of a vehicle body or a home appliance part. A metal surface partially comprising at least 90% zinc, aluminum and / or magnesium and / or an alloy of such metals or an alloy of such metal and other alloy elements; A rust-proofing method for a vehicle body or home appliance part to be cleaned, passivated and coated with a paint, wherein the vehicle body or home appliance part is subjected to pH 1-12, Ti, Zr, Hf, Si for the passivation. And / or B complex fluoride containing 20 to 500 mg / L as Ti, Zr, Hf, Si and / or B, and further containing a specific organic polymer 50 to 2000 mg / L, the composition thereof A rust preventive treatment method comprising contacting a treatment solution which is an aqueous solution set so that a crystalline zinc-containing phosphate layer is not formed on the metal surface. [Selection figure] None |