Patent ID: 9120251
Filing Date: 2015-09-01
Classification: B01D,B29C

Abstract:
1. A method for making an extruded composite material comprising a discontinuous phase of aligned fibers dispersed within a polymeric continuous phase, the method comprising, in order, the steps of: (a) combining from about 5 to 50 weight percent of high tenacity fibers having a tenacity of at least 9.0 grams per denier, a modulus of at least 300 grams per denier and a length of from 0.5 to 15 mm with about 50 to 95 weight percent of a polymer; (b) mixing the fibers and polymer at a temperature sufficient to melt the polymer thus forming a mixture comprising a discontinuous phase of fibers dispersed in a polymeric continuous phase; (c) cooling and forming the resultant mixture into particles or pellets; (d) feeding the pellets from step (c) and natural fiber to a mixer in an amount to produce a final composition comprising from about 2 to 15 weight percent of high tenacity fibers, from about 35 to 60 weight percent of natural fiber, and from about 25 to 63 weight percent of polymer based on the total weight of high tenacity fiber, natural fiber and polymer in the final composition; (e) applying vacuum to the mixer, heating the mixture to a temperature such that the pellets soften but do not melt and further mixing the high tenacity fiber-natural fiber-polymer composition into a homogeneous mass; (f) forming a composite panel by extruding the mixed homogeneous mass through a fiber alignment plate at an extrudate surface temperature not exceeding 260° C. such that at least 70% of the fibers are aligned in the flow direction; and (g) cooling and cutting to length the extruded panel.