NON-CHROMATE PRECOATED METAL PLATE EXCELLENT IN CORROSION RESISTANCE AFTER DEEP DRAWING AND METHOD FOR PRODUCING THE SAME, AND COATING COMPOSITION FOR PRODUCING THE PRECOATED METAL PLATE

摘要

PPROBLEM TO BE SOLVED: To provide a precoated metal plate which can stably maintain a high-level corrosion resistance without peeling of the coating and formation of blisters, even by not using a chromate rust preventive pigment and even after deep drawing exposed to a severe processing condition, and to provide a coating composition for over coating and under coating suitable for producing the precoated metal plate. PSOLUTION: The precoated metal plate, which has excellent coating adhesion and corrosion resistance even after deep drawing, is provided by subjecting a zinc-plated steel sheet, which has an amount of zinc plating per one side of 45 g/mSP2/SPor more, to conversion treatment on both sides thereof, and on the resultant sheet, forming an under coat and an over coat, each having a specified glass transition temperature, a number average molecular weight and a hydroxyl value. PCOPYRIGHT: (C)2005,JPO&NCIPI