Radiation-curable water-emulsifiable polyisocyanates

A water-emulsifiable, radiation-curable polyisocyanate (A) comprising, as synthesis components:

• a) at least one organic di- or polyisocyanate,
• b) at least one compound having at least one isocyanate-reactive group and at least one free-radically polymerizable unsaturated group and/or at least one cationically polymerizable group selected from optionally substituted acryloyl groups and optionally substituted vinyl ether groups,
• c) optionally, at least one further organic di- or polyisocyanate, different than a)
• d) at least one compound having precisely one isocyanate-reactive group and at least one saturated dispersive group,
• e) optionally, at least one compound having at least two isocyanate-reactive groups, and
• f) optionally, compounds different than a) to d) and having at least one isocyanate-reactive group,
• wherein
• the polyisocyanate (A) has an allophanate group, calculated as C2N2HO3 =101 g/mol, content of 1% to 30% by weight;
• the majority of the compound b) is attached via the allophanate groups;
• compounds carrying capped amino groups, carbamate end groups and/or urea end groups are excluded as synthesis components;
• the isocyanate content, calculated as NCO with the molecular weight 42 g/mol, is at least 3% by weight and up to 25% by weight;
• and
• the compound d) is at least one compound d3) which carries at least one nonionic group as a dispersive group, and is a monohydric polyalkylene oxide polyether alcohol comprising 5 to 90 ethylene oxide units.