Hardenable mixture of substances, production method and use thereof

A curable composition comprising

• (A) at least one constituent containing at least two carbamate groups of the general formula I:
• —O—C(O)—NHR (I)
• in which R is a hydrogen atom or a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, or a substituted or unsubstituted aryl group,
• (B) at least one constituent containing carbamate-reactive functional groups selected from the group consisting of methylol, methoxyalkyl, N-methylol, N-methoxyalkyl groups, and combinations thereof, an equivalents ratio of carbamate-reactive groups in (B) to carbamate groups in (A) being>0.2,
• (C) at least one adduct comprising a reaction product of
• (c1) at least one polyisocyanate and
• (c2) at least one compound of the general formula II containing an isocyanate-reactive functional group:
• wherein
• R1 and R2:
• independently of one another=hydrogen atoms or alkyl groups having from 1 to 10 carbon atoms;
• X and Y:
• independently of one another=oxygen atom, sulfur atom or a group>N—R6, in which R6=aliphatic group having from 1 to 30 carbon atoms, whose carbon chain may be interrupted by one or more oxygen atoms, or aromatic groups having from 6 to 30 carbon atoms;
• R3:
• alkylene group having from 1 to 5 carbon atoms;
• R4 and R5:
• independently of one another=hydrogen atoms, isocyanate-reactive functional groups or groups R6;
• with the proviso that one group R4, R5, or R6 contains an isocyanate-reactive functional group or one group R4 or R5 is an isocyanate-reactive functional group and the other radicals R4, R5, or R6—where present—contain no isocyanate-reactive functional groups;
• the molar ratio of polyisocyanates (c1) to compounds (c2) being chosen such that the adducts (C) still contain on average per molecule at least one free isocyanate group.