| 摘要 |
PROBLEM TO BE SOLVED: To obtain a one coat precoated steel sheet in which cracking, or the like, is hard to be generated on a coating film even to severe forming and capable of high speed operation at the time of the production. SOLUTION: The surface of a galvanized steel sheet subjected to chemical conversion treatment has a coating film of <=10μm dry film thickness formed by coating and baking a solvent type coating material compsn. essentially consisting of (A) 100 pts.wt. (in the ratio of the solid content) polyester resin having 5000 to 25000 number average molecular weight, 20 to 80 deg.C glass transition temp., 3 to 30 KOHmg/g hydroxyl group value and 0 to 10 KOHmg/g acid value, (C) 5 to 30 pts.wt. (in the ratio of the solid content) melamine resin and more preferably (B) 5 to 25 pts.wt. (in the ratio of the solid content) epoxy resin having 180 to 1000 epoxy equivalent, and in which 20 to 70 mol% in the polyhydric alcohol components of the polyester resin (A) is composed of cyclohexanedimethanol. |
