The present invention relates to A coating composition comprising a silicon heterocyclic compound and a hydroxyl-reactive cross-linker, wherein the silicon heterocyclic compound is a compound comprising at least one spiro-ortho silicate group, characterized in that the hydroxyl-reactive groups of the hydroxyl-reactive cross linker are selected from isocyanate groups, thioisocyanate groups, epoxy groups, episulfide groups, acetal groups, carboxylic acid groups, carboxylic anhydride groups, carboxylic acid ester groups, carbodiimide groups, alkoxy silane groups, Michael-acceptor groups, etherified amino groups, and mixtures thereof.