Continuous production of polyols for producing polyurethane, e.g. (semi)rigid foam or cell-free material, involves premixing crushed polyurethane or waste and polyol and reaction in extruder then at lower temperature in secondary reactor

摘要

In continuous production of polyols from polyurethane (waste) (PUR) by reaction with polyhydric alcohol (I), especially diol (IA), crushed PUR is mixed with (I/IA) in a separate stage (3) to a touch-dry, pourable mixture, which is stable in storage for several weeks under dry air; reacted in a multi-screw extruder (4) at 170-250[deg]C and elevated pressure not 50 bar to liquid product; and transferred in liquid form directly from extruder, with continuous stirring, to secondary reaction system (5a, 5b) operating at lower reaction temperature than extruder.