METAL PRETREATED WITH AN AQUEOUS SOLUTION CONTAINING A DISSOLVED INORGANIC SILICATE OR ALUMINATE, AN ORGANOFUNCTIONAL SILANE AND A NON-FUNCTIONAL SILANE FOR ENHANCED CORROSION RESISTANCE.

摘要

Painted metal sheet pretreated with an insoluble, composite layer containing siloxane. The composite layer is formed by rinsing the sheet with an alkaline solution containing at least 0.005 M of a dissolved silicate or a dissolved aluminate, at least 0.1 vol.-percent of an organofunctional silane and at least 0.02 vol.-percent of a crosslinking agent having two or more trialkoxysilyl groups. After the sheet is dried, the composite layer has a thickness of at least 10 Å. After being painted, the siloxane forms a tenacious covalent bond between the paint and the metal substrate.