Twin screw extruder for processing mixtures of plastics and natural fibers has screw profile to generate high pressures which squeeze natural resins out of fibers

摘要

The screw profile along its length is designed such that with mixtures containing 5-15% of plastic as a binder a pressure of not less than1000bar is produced in the output segment of the screw. An Independent claim is included for a process for extruding mixtures of plastic and natural fibers in the claimed extruder in which a mixture of natural fibers, e.g. wood flour and plastics, are conveyed and mixed in a hopper and fed into the twin screw barrel by a stuffing mechanism where it is plasticized, degassed and melted. Final extrusion through a die is effected with a pressure of not less than1000bar at the screw tip.