Polyether-modified polyisocyanate mixtures having improved dispersibility in water

A process for the preparation of a water dispersible polyisocyanate mixture having

• a) an average isocyanate functionality of at least 2.0,
• b) a content of 5.0 to 25.0 wt. %, based on resin solids, of isocyanate groups (calculated as NCO;
• molecular weight=42) and
• c) a content of 2 to 50 wt. %, based on resin solids, of ethylene oxide units (calculated as C2H4O;
• molecular weight 44) incorporated within polyether chains containing an average of 5 to 35 ethylene oxide units,
• which comprises reacting at an NCO/OH equivalent ratio of 6:1 to 400:1
• A) a polylsocyanate component containing polyisocyanate molecules prepared from at least two aliphatic, cycloaliphatic, araliphatic and/or aromatic diisocyanate molecules and having an average NCO functionality of 2.0 to 5.0 and having a content of aliphatically, cycloaliphatically, araliphatically and/or aromatically bound Isocyanate groups (calculated as NCO;
• molecular weight=42) of 8.0 to 27.0 wt. % and a content of monomeric diisocyanates of less than 1 wt. % with
• B) a monofunctional polyalkylene oxide polyether alcohol containing an average of 5 to 35 ethylene oxide units,
• and converting sufficient urethane groups initially formed by the NCO/OH reaction to allophanate groups, such that at least 60 mole % of the polyether chains are connected via allophanate groups to two polyisocyanate molecules which are each prepared from at least two dilsocyanate molecules.