Reusing glass-filled propylene scrap - by adding the scrap from separate extruder and then wood flour to stream of polypropylene in an extruder and expressing from flat sheet die

摘要

Composite materials are produced based on wood flour-filled polypropylene which contains 10-50 wt.% wood flour and 2-20 wt.% glass fibres of average length less than 2 mm; in the prodn. process the materials are mixed together and extruded in the form of flat sheeting. The glass fibres used are shavings from scrap glass mat-reinforced polypropylene. Pref. the polypropylene is first melted at 220-280 deg.C in an extruder (1) and the glass-filled polypropylene shavings are fused in a separate extruder before being fed in (3). The wood flour is added at the second stage (4). Any occluded air, water vapour or other decomposition products from the wood flour are drawn off from the degassing vent (5). Additional such vents can also be used, with or without the application of vacuum. The resultant mix is cooled to 200-240 deg.C and expressed from a flat sheet die (6). It solidifies to a sheet 20-200 cm wide 0.1-1 cm thick which can be bent, pressed, thermoformed etc. as required to produce e.g. door trims for cars etc. ADVANTAGE - The process provides a means of utilising glass-reinforced polypropylene scrap. (2pp Dwg.No.1/1)