IT1170628B - Rust resistant coating for steels - Google Patents

Abstract

Rust resistance of steel material, e.g. rolled steel plate, cast iron, etc., is improved by application of an aqueous soln. or emulsion which contains (1) 0.001 to 10 wt. % 1-hydroxybenzotriazole with the formula (I)(where X, Y is a hydrogen atom, or hydroxy, alkyl, carboxyl, nitro or sulfo gp.) and (2) 0.01 to 5 wt. % of one or more aliphatic dicarboxylic acids, e.g., suberic, azelaic or brasilic acid, and whose pH is adjusted to 7-10 by neutralization with aqueous ammonia, hydrazine, or monoethanolamine, triethanolamine or similar alkanolamine. The amount of both components (1) and (2) is pref. 0.1 to 2 wt. %. The soln. or emulsion may also contain 0.01 to 2 wt. % high polymer cpd. or 0.001 to 0.5 wt. % surfactant to impart uniformity or corrosion resistance to the applied film.. The method gives rust protection without requiring removal of protective coating before a subsequent steel material treatment stage, but avoids the problems of discoloured stains that occur in high-temperature, moist atmosphere storage of steel protected with coating using 1-hydrobenzotriazole alone.