Abstract: The invention relates to coating agents, containing (A) at least 50 wt. %, (in relation to the content of non-volatile substances in said coating agent), of at least one compound (A1) and/or (A1?) comprising at least two reactive groups of formula (I): —X—SiR?x(OR?)3-x, in which R?=hydrogen, alkyl or cycloalkyl, whereby the carbon chain can be interrupted by non-adjacent oxygen, sulphur or NRa groups, Ra=alkyl, cycloalkyl, aryl or aralkyl, X=a linear and/or branched alkene or cycloalkene group comprising between 2 and 20 carbon atoms, R?=alkyl, cycloalkyl, aryl or aralkyl, whereby the carbon chain can be interrupted by non-adjacent oxygen, sulphur or NRa groups, and x=0 to 2, (B) a catalyst for cross-linking the —Si(OR?)3-x units, and (C) an organic solvent or a mixture of organic solvents.