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United States Patent 4944597
Douris , ê et al. July 31, 1990

Extrusion apparatus

Geyer July 31, 1990

Abstract

An extruder, including a rotor and a barrel having a mixing or working section therein, in which all of the material being worked is in barrel grooves and is moved only in a circumferential direction by a smooth cylindrical rotor. The barrel groove consists of wide tapering in depth area, which starts deep and progressively decreases in depth to the downstream end where the depth is restrictive to oversize and viscous material. Well worked material passing the barrier is separated from and directed downstream, thus providing fast forward flow of the fluent phase material, minimizing the rework of already worked material and exposing the less worked material to extruder action. The tapering depth area coacting with the smooth rotor generates progressively high pressure, and an increasing shear rate along its length and thereby provides the ideal conditions for dispersing powdered chemicals into the polymer. All of the material being worked uniformly, need for dwell time is eliminated, extruder length can be such that the input work is only equal to the heat required to raise the material to temperature or adiabatic operation. Thus a short high speed inexpensive extrusion apparatus is provided which produces a superior pulseless extrusion.