Weather-resistant radiation curable polyurethanes

摘要

A water dispersible, radiation curable polyurethane comprises organic aliphatic or alicyclic polyisocyanates, cycloaliphatic diols and/or cycloaliphatic diamines, compounds having at least one isocyanate reactive group and at least one radically polymerizable unsaturated group and compounds having at least one isocyanate reactive group and at least one dispersion aiding group. A water dispersible, radiation curable polyurethane (I) comprises: (A) organic aliphatic or alicyclic polyisocyanates; (B) cycloaliphatic diols and/or cycloaliphatic diamines; (C) compounds having at least one isocyanate reactive group and at least one radically polymerizable unsaturated group; (D) compounds having at least one isocyanate reactive group and at least one dispersion aiding group; (E) optionally compounds having at least two isocyanate reactive groups having a mol. wt. of less than 1000 g/mol; (F) optionally compounds having at least one isocyanate reactive group that are different to (A)-(D). Independent claims are included for: (i) a polyurethane dispersion (II) comprising the polyurethane (I) and optionally 0-10 wt.% of a photochemical and/or thermal initiator and 0-10 wt.% of a UV absorber and a HALS compound; (ii) a process for the coating of substrates by application of the polyurethane dispersion (II), optionally containing conventional paint additives, onto a substrate and curing by means of electron irradiation or UV light under oxygen, or preferably under inert gas; (iii) the resulting coated substrate.