Verfahren zur Herstellung von thermoplastisch verarbeitbaren Polyurethanen

Die Erfindung betrifft ein mehrstufiges Verfahren zur Herstellung von thermoplastisch verarbeitbaren Polyurethanen mit verbessertem Verarbeitungsverhalten, insbesondere verbesserter Homogenität. Production of thermoplastic polyurethane elastomers (TPU) involves (A) mixing (a) linear hydroxyl (OH)-terminated polyol(s) (molecular weight (Mw) 500-5000) with (b) organic diisocyanate in isocyanate (NCO)-reactive/NCO group equivalent ratio of (1.1-5.0):1 in mixing aggregate with high shear energy; (B) over 90% conversion to OH-terminated prepolymer (I) by reaction at over 80[deg]C; (C) mixing (I) with (c) chain extender(s) (Mw 60-490); (D) conversion to TPU by reaction with (b) to adjust overall equivalent ratio of NCO/NCO-reactive groups to (0.9-1.1):1. Production of thermoplastic polyurethane elastomers (TPU) with improved processability uses a multistage reaction comprising (A) mixing (a) linear hydroxyl (OH)-terminated polyol(s) of weight average molecular weight 500-5000 with (b) an organic diisocyanate in an equivalent ratio of isocyanate (NCO)-reactive groups to NCO groups of (1.1-5.0):1 in a mixing aggregate with high shear energy; (B) reacting the resultant mixture at temperatures above 80[deg]C to over 90% conversion with respect to (b), to a OH-terminated prepolymer (I); (C) mixing (I) with (c) chain extender(s) of molecular weight 60-490; (D) conversion to the TPU by reacting the mixture with component (b) in such an amount that the overall equivalent ratio of NCO/NCO-reactive groups is adjusted to (0.9-1.1):1. Stages (A) to (D) may take place in the presence of catalyst and with addition of 0-20 wt.% ancillaries and additives with respect to the total amount of TPU. An independent claim is included for use of the TPU for producing injection molded and extruded articles.