[en] PROBLEM TO BE SOLVED: To provide a process for preparing a binder which contains (1) an allophanate group, (2) a group that reacts with an ethylenically unsaturated compound with polymerization on exposure to actinic radiation (radiation-curing group) and (3) optionally an NCO-reactive group; and to provide the binder obtained by the process. ; SOLUTION: The process comprises reacting at a temperature <=130[deg.]C, (A) one or more NCO-functional compounds containing uretdione groups with (B) one or more compounds that contain isocyanate-reactive groups and radiation-curing groups and then (C) with one or more saturated hydroxy-containing compounds other than (B), at least one of these compounds having an OH functionality of >=2, in the presence of (D) a catalyst containing one or more zinc compounds, the reaction with compounds (C) taking place at least proportionally with the formation of allophanate groups.