Coating composition and method for producing precoated steel sheets

Abstract

This invention relates to a coating composition for precoated steel sheets which are required to have high hardness, high workability and high distinctness of image, and to a method for producing a precoated steel sheet having a coating film of the composition. The composition is prepared by adding a compound of any of the following (a) to (c) to a coating composition consisting essentially of a polyol and containing, as the curing agent, an isocyanate compound or an amino resin, and the coating film of the composition has both high-level workability and high-level hardness. (a) Polyester compounds comprising main repeating units of a general formula (1): ##STR1## wherein n is an integer; and R is an alkylene group having 10 or less carbon atoms, or a 1,4-cyclohexylene-dimethylene group, or a neopentylene group, or a polyoxyalkylene group. (b) Polyester compounds comprising main repeating units of a general formula (2): ##STR2## wherein n is an integer of 10 or less; and R is an alkylene group having 10 or less carbon atoms, or a 1,4-cyclohexylene-dimethylene group, or a neopentylene group. (c) Compounds having the structure of a general formula (3): HO--(CH.sub.2).sub.n --O--R--O--(CH.sub.2).sub.n --OH (3) wherein n is an integer of from 2 to 10; and R is ##STR3##

Dependencies are inferred from the claim text.