[en] A radiation-curing binder containing allophanate groups is prepared by reacting at =130[deg]C compound(s) containing uretdione groups with OH-functional compounds containing groups reacting with polymerization with ethylenically unsaturated compounds on exposure to actinic radiation, optionally other NCO-reactive compounds, in the presence of a catalyst comprising at least one zinc compound to form allophanate groups by opening the uretdione ring. Independent claims are also included for: (A) a coating composition comprising the radiation-curing binder(s) containing allophanate groups, optionally polyisocyanate(s) containing free or blocked isocyanate groups, which are free from groups which react, with polymerization, with ethylenically unsaturated compounds on exposure to actinic radiation, optionally other compounds containing groups which react, with polymerization, with ethylenically unsaturated compounds on exposure to actinic radiation, and optionally contain free or blocked NCO groups, optionally one or more isocyanate-reactive compounds, initiator(s), and optionally solvents; and (B) a substrate coated with a coating obtained from the radiation-curing binder containing allophanate groups.
