Organopolysiloxane resins formed with catalysts of formic acid and

Abstract

A process for forming organopolysiloxanes from trialkoxysilanes and the resulting resinous products are disclosed, characterized in that the organopolysiloxane resins have increased abrasion and solvent resistance with good shelf life. The organopolysiloxanes are formed by dual catalysts that operate preferably in sequence. Hydrolysis and condensation of the trialkoxysilanes are carried out in an aqueous solution and catalyzed by formic acid at a relatively high strength, such as an amount greater than 700 ppm. Cross-linking of the resulting partially condensed, curable organopolysiloxane is then catalyzed by a hydrocarbyl substituted ammonium hydroxide in which the hydrocarbyl substituent may be alkyl or alkenyl up to about 6 carbon atoms. The resinous products are especially useful as coating compositions.