Process for the preparation of polyurethanes which are dispersible in water

A process for the preparation of water dispersible, substantially linear polyurethanes characterized by a content of from 0.5 to 10%, by weight, of ethylene oxide units built into terminal polyether chains and from 0.1 to 15 milliequivalents of ionic groups per 100 grams of polyurethane, said process comprising reacting:

• (a) an organic diisocyanate,
• (b) an organic compound, which behaves as a difunctional material in the reaction with the diisocyanate and which contains isocyanate reactive hydrogen atoms,
• (c) a first hydrophilic material selected from the group consisting of
• (i) monoisocyanates which contain hydrophilic chains containing ethylene oxide (i.e., --CH.sub.2 --CH.sub.2 --O--) units,
• (ii) compounds which are monofunctional in the isocyanate polyaddition reaction, which contain isocyanate reactive hydrogen atoms, and which contain ethylene oxide units, and
• (iii) mixtures thereof, and
• (d) a second hydrophilic material selected from the group consisting of
• (i) mono- and/or diisocyanates which contain ionic groups and/or groups capable of conversion into ionic groups,
• (ii) compounds which are mono- and/or difunctional in the isocyanate polyaddition reaction, which contain isocyanate reactive hydrogen atoms and which contain ionic groups and/or groups capable of conversion into ionic groups.