The present invention relates to a process for preparing a mixed silane-terminated polymer by reacting a polyol component A) with a diisocyanate component B) comprising 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), at least one isocyanatosilane C) and an aminosilane E), in which the urethanization reaction is carried out in the presence of at least one catalyst D) which is free of organically bonded tin. The invention further relates to the use of the polymers thus obtained.