| abstract |
TWO-STACE PROCESS FOR THE PREPARATION OF THERMOPLASTIC POLYURETHANE ELASTOMERS Abstract of the Disclosure In order to prepare thermoplastic polyurethane elastomers a) organic diisocyanate, b) polyhydroxyl compounds with molecular weights of 500 to 8,000, and c) chain extenders with molecular weights of 60 to 400 in the presence of d) catalysts, and optionally e) auxiliaries, and/or f) additives are reacted in two reaction stages at temperatures from 60°C to 250°C. In the first reaction stage the components are continuously mixed, the reaction mixture is applied to a carrier, preferably a conveyor band of thermoplastic material, and is allowed to react at the reaction tempera-ture until solidified. Suhsequently, the solidified reaction mixture is melted in an extruder and the reaction is completed in the second reaction stage. |