Process for producing natural and / or synthetic fiber-reinforced compounds by means of twin-screw extruders

摘要

Natural and/or synthetic fibers are fed to an extruder, preferably a twin screw extruder, and compounded with a polymer before either granulating or extruding to form sheets or other semi-finished products. In order to achieve maximum physical properties in the compound the fibers and plastics are processed in textile and plastics processing equipment which ensure that the particular characteristics of the materials, e.g. poor or only moderate flow of the fibers or compounds, is considered. Fibers supplied in compacted form are opened up(I) using bale openers, bale mills or shredders with mills, then metal particles(II) and dust(III) are removed. The continuous fiber flow is then converted into an intermittent flow to allow metering(IV) by weight into the plasticizing zone(20a) of the extruder(VII). Pressure build up in the extruder is reduced by a melt pump(24) prior to the nozzle plate(25). Extruded strands of compound are granulated under water(IX), Sheet extrusion is aided by a polishing roll mill or double belt press. Extrusion of semi-finished products is achieved using either a conventional nozzle and take-off unit via nozzle or by continuous laydown of melt followed by intermittent compression.