| 摘要 |
PROBLEM TO BE SOLVED: To obtain a precoated steel plate capable of attaining excellent characteristics including worked part corrosion resistance even if a chrome based rustproofing pigment is not added in the coating film. SOLUTION: The precoated steel plate is obtained by forming an under coating film, in which a rustproofing additive releasing phosphate ion and a rustproofing additive releasing vanadate ion under a water-existing environment are combined and added, on the surface of a galvanized steel plate, on which a chemically treated coating film containing silica fine particle and a binder is formed, and further a top coating film formed by applying a coating material composition containing the following (a) to (c) in a prescribed ratio on the upper layer. (a) A polyester compound having a repeating unit expressed by formula 1. (In the formula, (n) represents integers of 2-10, R represents polyoxymethylene group, 1,4-cyclohexylene dimethyl group, neopentylene group or-(CH2)m- ((m)=1-10) and R' represents a group expressed by formula 2 or formula 3). (b) A polyol except the polyester compound of (a) and (c) A curing agent.
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