Aqueous polyurethane dispersions which can be hardened with mit UV-radiation and thermally, and use thereof

A UV- and heat-curable aqueous polyurethane dispersion synthesized essentially from

• a) aliphatic polyisocyanates having an NCO functionality of from 2 to 4.5,
• b) compounds containing at least one isocyanate-reactive group and at least one C═C double bond UV-polymerizable, in the presence of a photoinitiator,
• c) aliphatic compounds containing at least two isocyanate-reactive hydroxyl, mercapto, primary and/or secondary amino groups, having a molecular weight of less than 500 g/mol,
• d) compounds containing at least one isocyanate-reactive group and also at least one carboxyl group or sulfonic acid group,
• e) at least one basic compound for full or partial neutralization of the acid groups of the compounds d),
• f) an isocyanate blocking agent (f1) which converts isocyanate groups into blocked isocyanate groups with an unblocking temperature in the range from 70 to 160° C., or addition of a low molecular mass compound (f2) containing blocked isocyanate groups, and
• g) if desired, a compound other than compounds b) to f) which contains only one isocyanate-reactive group,
• the reaction products of a) with b) and c), prepared with a stoichiometric excess of NCO groups in relation to hydroxyl groups, having been reacted with compounds d) and e) in amounts sufficient for dispersibility in aqueous medium, blocked isocyanate groups having been introduced into the molecule by reaction with isocyanate blocking agents (f1), or compounds (f2) containing blocked isocyanate groups having been added.