Coating composition for metal substrates

摘要

The present invention relates to a composition for coating a metal substrate which is intended to be fabricated and overcoated, and wherein the binder comprises an aqueous silica sol or alkali metal silicate having a SiO2/M2O mole ratio of at least 6:1, where M represents total alkali metal and ammonium ions, and wherein the silica particles have an average size equal to or smaller than 10 nm. Very good results are obtained if the dried coating is post-treated with a film-strengthening solution.