Polyurethane polymers

A polymer modified with alkoxysilane groups, which are obtainable by reacting

• a) compounds or mixtures of compounds having isocyanate-reactive groups and a hydroxyl number or amine or thiol number of greater than 30 mg of KOH/g+
• with
• b) an isocyanate-functional alkoxysilane compound of the general formula (I):
• wherein
• Z1, Z2 and Z3 are identical or different C1-C8-alkoxy or C1-C8-alkyl radicals,
• which can also be bridged, but wherein at least one C1-C8-alkoxy radical must be present on each Si atom,
• Q is an at least difunctional linear or branched organic radical.