PRE-COATED STEEL PLATE WHICH IS EXCELLENT IN ENVIRONMENTAL HARMONY, WORKED SECTION ANTICORROSIVE PROPERTY, AND WORKED SECTION ADHESION

摘要

PROBLEM TO BE SOLVED: To provide a pre-coated steel plate wherein excellent worked section anticorrosive property and worked section adhesion being equivalent to those of a highly anticorrosive chrome based pre-coated steel plate can be obtained without adding a chrome based rustproof pigment in the coating film. SOLUTION: An undercoating film is formed on the surface of a zinc-based plated steel plate wherein a chemical conversion treatment film containing a silica particle and its binder is formed. In addition, a finish coating film is formed on the upper layer of the undercoating film for this pre-coated steel plate. In this case, the finish coating film contains 1 to 20 pts.wt. of a rustproof additive component comprising one kind or two kinds or more of organic compounds selected from among a molybdate, or a molybdate and triazoles, thiols, thiadiazoles, thiazoles, and thiurams, based on 100 pts.wt. of a resin solid portion.