US Patent 7902315 Low viscosity allophanates containing actinically curable groups

The present invention relates to a process for preparing radiation-curing binders containing allophanate groups by reacting at temperatures of ≦130° C.A) one or more compounds containing uretdione groups withB) one or more OH-functional compounds which contain groups which react, with polymerization, with ethylenically unsaturated compounds on exposure to actinic radiation (radiation-curing groups),C) optionally NCO-reactive compounds other than B),in the presence ofD) a catalyst containing at least one zinc compound,to form allophanate groups by opening the uretdione ring.