摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a one-coat precoated steel panel less prone to generate a crack in a coating film even in severe molding processing and enabling high speed operation at a time of production. SOLUTION: The surface of a galvanized steel panel to which chemical forming treatment is applied is coated with a solvent type paint compsn. wherein a polyester resin with a number average mol.wt. of 5,000-25,000, a glass transition temp. of 20-80 deg.C, a hydroxyl number of 3-30 KOH mg/g and an acid value of 0-10 KOH mg/g, an epoxy resin with an epoxy equivalent of 180-1,000 and a curing agent consisting of a blocked polyisocyanate compd. and a melamine resin are compounded as main components in a specific ratio and, especially pref., 20-70 mol% of the polyhydric alcohol of the polyester resin is an ethylene oxide adduct of bisphenol A and/or a propylene oxide aduct of bisphenol A represented by the formula and the coated steel panel is baked to form a coating film with a dry film thickness of 10μm or less.</p> |