Twin screw extruder for processing natural fibers in wood flour or similar form has a screw profile to create frictional heat in the fibers and high pressures

摘要

The screw geometry is designed so that natural fibers are heated to 140-200degreesC by friction and a pressure of not less than1400bar is produced. Only small quantities of additives are added to the natural fibers. An Independent claim is included for a process for extruding natural fibers in the form of wood flour or similar in the claimed twin screw extruder in which the fibers are conveyed and mixed in a hopper and fed into the twin screw extruder barrel by a stuffing mechanism. In the barrel the fibers are heated and degassed and the resin content of the fibers melts to form a binder matrix for the fibers before being extruded through a die. Pressure in front of the screw tip is not less than1400bar.