Aqueous polymer compositions comprising polyurethane (meth)acrylates

An aqueous polymer composition comprising in dispersed form

• A at least one polyurethane (meth)acrylate constructed from the following structural components:
• A1 an isocyanate A1 component comprising:
• A1a at least one polyisocyanate obtained by oligomerization of at least one diisocyanate and having an average isocyanate functionality of at least 2.5, the diisocyanate having at least one saturated alicyclic structural unit;
• and
• A1b at least one diisocyanate selected from saturated aliphatic and saturated alicyclic diisocyanates;
• A2 as component A2, at least one compound which has at least one ethylenically unsaturated double bond in a form of an acrylic or methacrylic group, and also has at least one functional group F which reacts with an isocyanate group to form a covalent bond;
• A3 at least one neutral polyol component A3 comprising
• A3a at least one aliphatic, polymeric polyol having an average OH functionality in the range from 1.5 to 2.5;
• A3b at least one low molecular weight diol compound having a molecular weight of not more than 400 g/mol and selected from saturated aliphatic and saturated alicyclic diols;
• and
• A4 as component A4, at least one compound which has at least one ionic or ionizable group I′ and at least one functional group F′ which reacts with an isocyanate group to form a covalent bond;
• and
• B at least one compound B having a molecular weight below 1000 g/mol and having at least two ethylenically unsaturated double bonds per molecule, the ethylenically unsaturated double bond being present in a form of acrylic or methacrylic groups,
• wherein the compound B has a water-solubility of not more than 5 g/L, determined in deionized water at 25° C. and 1 bar.