Process for the preparation of thermoplastic, non-tacky polyurethanes
View Patent ↗Thermoplastic polyurethanes (TPU) with a low tendency towards surface tackiness of the granules are prepared by applying at least one wetting agent satisfying specified criteria and at least one solid powdering agent to the TPU before and/or after comminution of the TPU.
1. A process for the preparation of granules from a thermoplastic polyurethane which is the reaction product of
A) a cycloaliphatic diisocyanate with
B) at least one polyol having a number-average molecular weight between 600 and 8,000 g/mol and
C) at least one chain-lengthening agent having a number-average molecular weight between 60 and 500 g/mol with the addition of
D) optionally, a catalyst and
E) optionally, a conventional auxiliary substance and/or additive, comprising
(1) applying in succession
(a) at least one wetting agent which is liquid at ≦30° C. in a concentration of 0.01 to 0.5 wt. %, based on the sum of the weights of A, B and C, and thereafter
(b) at least one solid powdering agent with a melting temperature of ≧70° C. in a concentration of 0.01 to 0.5 wt. %, based on the sum of the weights of A, B and C to the thermoplastic polyurethane before and/or after
(2) comminuting the thermoplastic polyurethane.
2. The granules produced by the process of claim 1 .