| 摘要 |
PURPOSE:To markedly enhance corrosion-proofness, by applying an aqueous under-coat, wherein the water absorption of a dried paint film shows a specific value or more, to a zinc plated steel material and subsequently applying a paint having corrosion-proof pigment, wherein the electric conductivity of an aqueous extract is a specific value or more, compounded therein. CONSTITUTION:An aqueous paint A, wherein water absorption of a dried paint film is 0.3-20wt% at 50 deg.C, is at first applied to a zinc plated steel material. This paint A is selected from an electrodeposition paint based on a vehicle component and water, an aqueous solution paint or an emulsion paint. Next, a paint B having corrosion-proof pigment, wherein the electric conductivity of a water extract is 100muV/cm or more, compounded therein is applied to the coating surface of the paint A. In this case, as the corrosion-proof pigment, lead pigment or chromate pigment having function suppressing or preventing the corrosion of a metal is used. By this paint film forming method, the corrosion proofness of an aqueous under-coat is enhanced without lowering the storage stability and paint finishing property thereof.
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