Ared from methyltrialkoxy silanes - ared from methltrialkoxy silanes

摘要

Easily cleaned, hard, weather-proof, solvent-resistant coating on metal, pref. Cu or Al, is obtained by applying a hardenable organopolysiloxane (A) dissolved in an organic solvent, pref. with addition of a u.v. absorber, e.g. 2-hydroxy-4-methoxybenzophenone. (A) is prepared from a methyltrialkoxysilane or mixture thereof with a phenyltrialkoxysilane in which the alkoxy groups contain less than 5 C atoms, by hydrolysis with water at 50-80 degrees C in 1-10 hrs. with formation of a partly condensed organopolysiloxane; heating to 80-300 degrees C to remove alkanol by-product formed and water, and converting the product by heating at temp. below its gelation point but within the 90-183 degrees C rang into the prehardened, still hardenable organopolysiloxane, which hardens on the metal surface by evaporating the solvent.