Method for the preparation of radiation-curable urethane (meth)acrylates

The invention relates to urethane (meth)acrylates that can be obtained by performing the following steps: (r1) partially reacting an alkoxylated polyol (A) with (meth)acrylic acid (B) in the presence of at least one esterification catalyst (C) and at least one polymerization inhibitor (D) and optionally a solvent (E) that forms an azeotrope with water, (01) optionally removing at least part of the water arising in (r1) from the reaction mixture, wherein (01) can occur during and/or after (r1), (02) optionally neutralizing the reaction mixture, (03) if a solvent (E) was used, optionally removing said solvent by distillation and/or (04) stripping by means of a gas that is inert under the reaction conditions, (r2) reacting the reaction mixture obtained after the last of the preceding reaction steps with a compound (G) having at least two epoxy groups optionally in the presence of a catalyst (H), and (r3) reacting the reaction mixture from (r2) with at least one polyisocyanate (J) and at least one hydroxyalkyl (meth)acrylate (K) and optionally at least one further compound (M) containing one or more groups reactive with isocyanate, in the presence of a catalyst (L), provided that the catalyst (L) used in step (r3) is a catalyst that contains bismuth.