Radiation-curable formulations with high adhesion

A radiation-curable formulation comprising

• (A) 20 to 50 weight % of at least one condensation resin synthesized from urea or urea derivatives a1) and ketones or aldehydes a2) selected from C—H acidic aldehydes and ketones or mixtures thereof with formaldehyde,
• (B) 20 to 40 weight % of at least one radiation-curable compound having at least 2 acryloyl or methacryloyl groups,
• (C) 2 to 10 weight % of at least one radiation-curable compound having free acid groups,
• (D) 10 to 30 weight % of at least one (meth)acrylic acid alkyl ester whose alkyl radical has at least 8 carbon atoms,
• (E) 1 to 10 weight % of at least one coating auxiliary and/or additive, and
• (F) 0.5 to 5 weight % at least one photoinitiator,
• wherein:
• amounts for components (A), (B), (C), (D), (E), and (F) sum to 100 weight %, and
• the formulation has an acid number of 10 to 100 mg KOH/g, based on the sum of components (A) to (F).