Process for the preparation of aqueous polyurethane-polyurea dispersions

摘要

The present invention is directed to a process for the preparation of stable polyurethane-polyurea dispersions in a multi-stage process by forming an isocyanate-terminated prepolymer having an ionic group content of up to about 50 milliequivalents per 100 g of prepolymer by reacting an organic polyisocyanate (a) with at least two isocyanate-reactive components (b1) and (b2) wherein component (b1) has at least one ionic or potential ionic hydrophilic group, characterized in that (1) the isocyanate (a) is initially reacted with component (b1), and (2) the resulting product is then reacted with component (b2) and optionally with a component (b3) containing ethylene oxide units to form a prepolymer, and (3) the resulting prepolymer is dispersed in water. The present invention further release to products obtained according to this process and to their use for the preparation of coatings on flexible or rigid substrates and in particular to their use as ahdesives.