PROCESS FOR THE PRODUCTION OF RADIATION-CROSSLINKED THERMOPLASTIC POLYURETHANES

摘要

Mo-2901 LeA 24,492 A PROCESS FOR THE PRODUCTION OF RADIATION CROSSLINKED THERMOPLASTIC POLYURETHANES The invention is directed to a process for the production of polyurethanes suitable for thermoplastic processing comprising mixing I. at least 75 % by weight of preformed thermoplastic polyurethane elastomers, or of a blend of (A) substantially bifunctional, compounds (B) substantially bifunctional chain-extending agents (C) organic diisocyanates and optionally (D) lubricants or other known additives said blend characterized in that it contains no peroxides and polymerization initiators which decompose into radicals under the effect of actinic light and further in that the molar ratio of the sum of said (A) and said (B) to said (C) is between 0.9 to 1.1, with II. (E) from 4 to 24X by weight of a crosslinking agent and III. (F) from 0,01 to 3% by weight of a polymerization inhibitor and/or an antioxidant, by adding said II and said III to said I as a temperature below 230.degree.C, and then cooling the mixture to below 130.degree.C in less than 5 minutes in a continuous extruder and optionally granulating the resulting polyurethane. Mo-2901