Process for the continuous production of aqueous polyurethane dispersions

A process for producing an aqueous polyurethane dispersion of a polyurethane having carboxyl groups, said method comprising

• i. providing a liquid mixture of polyol compounds consisting essentially of
• a) at least one aliphatic diol compound a) bearing at least one carboxyl group;
• b) at least one polymeric polyol compound b) having on average from 1.5 to 2.5 hydroxyl groups per molecule;
• c) optionally one or more further active hydrogen compounds c) which are different from the compounds a) and b);
• wherein all components of the liquid mixture are present in mutually dissolved form;
• ii. continuously feeding the liquid mixture of polyol compounds provided in step i. and at least one isocyanate compound having at least 2 isocyanate groups per molecule simultaneously into a continuously operated reactor under conditions, wherein a polyurethane having carboxyl groups is produced;
• and
• iii. continuously discharging the polyurethane produced in step ii. from the reactor and continuously dispersing the polyurethane of step ii. in water.