process for the production of hochviskosem polyhexamethylenadipamid

摘要

The invention relates to a process for the preparation of high-viscosity polyhexamethyleneadipamide by post-polycondensation of the melt of a polymer having a relative viscosity of 2.5-2.7 (measured in 1% solution in 96% sulphuric acid) in a twin-screw extruder having co-rotating, mutually engaging screws and vent (degassing) zones, where the polymer melt is polycondensed by treatment in a plurality of successively arranged zones of alternating increased and reduced pressure in the extruder, where steam superheated to the temperature of the melt is fed to the melt in the zones of increased pressure in an amount of 0.05-0.7 kg/kg of polymer, the vapour (steam) phase which has been fed in and the water of condensation are removed in the zones of reduced pressure, and the temperature of the melt is increased uniformly over the length of the extruder from 260-280 DEG C in the first zone to 280-310 DEG C in the final zone.