| abstract |
This invention provides an organic composite coated steel sheet comprising, as the base, a zinc or zinc alloy coated steel sheet, which can be used in automobile bodies and electric appliances. The coated steel sheet has excellent press formability with oil, while having excellent perforation corrosion resistance and excellent corrosion resistance in a rust-contaminated environment. The coated steel sheet comprises a zinc or zinc alloy plated steel sheet having, on its surface, a chromate layer and an organic film formed in that order, in which the organic film has a thickness of from 0. 1 to 3. 0 µm and comprises (i) an epoxy resin mixture composed of a base resin as prepared by adding at least one basic nitrogen atom and at least two primary hydroxyl groups to the ends of an epoxy resin, and a curing agent for the resin of a polyisocyanate compound, as mixed in a particular ratio by weight of the two, (ii) a composite lubricant comprising a polyolefin wax as prepared through coordination-anionic polymerization using a Ziegler catalyst, and fine powder of a fluorine resin, as combined in a particular ratio by weight of the two, and (iii) a rust preventive additive, as combined in a particular ratio of (i) , (ii) and (iii). |