RADIATION CURABLE AQUEOUS COMPOSITIONS WITH CONTROLLED POLYMER FLOW

Provided in the invention is an aqueous radiation curable composition (I) comprising : - at least one ethylenically unsaturated polyurethane (A) obtained from the reaction of at least one polyisocyanate compound (Ai); at least one ethylenically unsaturated compound (Aii) containing at least one reactive group capable to react with isocyanate groups; at least one hydrophilic compound (Aiii) containing at least one reactive group capable to react with isocyanate groups and at least one other group which is capable to render the polyurethane polymer dispersible in aqueous medium as such or after the formation of a salt; optionally, at least one polyol (Aiv); optionally, at least one further compound (Av) different from the polyol (Aiv) and comprising at least one reactive group capable to react with isocyanate groups; and optionally, at least one reactive electrophilic compound (Avi); said ethylenically unsaturated polyurethane (A) preferably being characterized by a molecular weight that is above 1,000 Daltons; - at least one ethylenically unsaturated polyurethane (B), different from the polyurethane (A), obtained from the reaction of at least one polyisocyanate compound (Bi); at least one ethylenically unsaturated compound (Bii) containing at least one reactive group capable to react with isocyanate groups; optionally, at least one polyol (Biv); optionally, at least one further compound (Bv) different from the polyol (Biv) and comprising at least one reactive group capable to react with isocyanate groups; and optionally, at least one reactive electrophilic compound (Bvi); said ethylenically unsaturated polyurethane (B) preferably being characterized by a molecular weight that is below 10,000 Daltons; and - optionally, at least one ethylenically unsaturated compound (C) different from (A) and (B); wherein the radiation curable composition (I) in dry form has a steady-state creep viscosity · 30 , expressed as the apparent viscosity after a deformation time of 30 minutes with a load Ã0 = 50 Pa at 23°C, that is above 1.10 3 Pa.s, more preferably above 1.10 4 Pa.s. Compositions (I) of the invention are characterized by an improved creep viscosity · 30 and provide polymer materials with a good flow and mirror effect. In general these materials are less sensitive to dust pick-up and fingerprints. Further provided in the invention is a one-vessel solvent free process for preparing such materials.