Reflux coolers to limit filtered melt temperatures - for continuous extrusion, esp. of polyesters, at controlled melt temp.

摘要

System for restricting heat build-up in polymeric melts due to passage through a filter, comprises locating downstream from the filter a passage intersected by >=1 hollow finger contg. a volatile fluid beneath reflux condensers. Used esp. for limiting the upper melt temps. of non-Newtonian polymers during high speed extrusion of fine filaments or other applications requiring filtered material of controlled melt viscosity. System is partic. claimed for extruding polyesters at a nominal melt temp. of 286 degrees C with coolant chamber melt temp. maintained at 288-292 degrees C max. System can accept melt of varying temp. resulting from successive alternate use of two filter units installed in parallel between an extruder and a filament die, to allow each filter to be purged without stopping throughput. By suitable choices of reflux fluids and reflux chamber pressure, the cooling chamber may be adjusted to control to specific limits with a tolerance of =4 degrees C.