Elongated molding granules and injection-molding process employing them
AssigneeAmerican Cyanamid Company
InventorsBruce A. Luxon, Malalur V. Murthy
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Abstract
Elongated granules of reinforcing fibers extending generally parallel to each other longitudinally of the granule substantially uniformly dispersed throughout a thermally stable, readily melting, film forming thermoplastic adhesive, providing complete dispersion of the fibers during an injection molding cycle, conserving physical properties and providing significantly better EMI shielding than prior art extruder compounded resin/fiber blends.
Claims19
A method of manufacturing injection molding granules of dispersible filaments comprising the steps of continuously passing reinforcing filaments through at least one bath of a thermally stable, readily melting film forming non-crosslinkable thermoplastic adhesive, which substantially disperses on contract with hot molten plastic, in a liquid medium to impregnate the filaments, passing the impregnated filaments through a sized opening to remove any excess adhesive, passing the treated filaments into a heated zone first to evaporate the liquid medium and then to flux the thermoplastic adhesive, and withdrawing the treated filaments from said zone and thereafter chopping them into elongated granules whereby there are produced granules comprising 67.5-97.5% by volume of reinforcing filaments extending generally parallel to each other longitudinally of the granule and substantially uniformly dispersed throughout said granule in from 2.5-32.5% by volume of said thermoplastic adhesive which substantially surrounds each of said filament.
A method of manufacturing injection molding granules of dispersible filaments comprising the steps of continuously passing reinforcing filaments through at least one bath of a thermally stable, readily melting film forming thermoplastic adhesive consisting of a poly(C.sub.2 -C.sub.6 oxazoline), alone or in further combination with a polymeric plasticizer, in a liquid medium to impregnate the filaments, passing the impregnated filaments through a sized opening to remove any excess adhesive, passing the treated filaments into a heating zone first to evaporate the liquid medium and then to flux the thermoplastic adhesive, and withdrawing the treated filaments from said zone and thereafter chopping them into elongated granules whereby there are produced granules comprising 67.5-97.5% by volume of reinforcing filaments extending generally parallel to each other longitudinally of the granule and substantially uniformly dispersed throughout said granule in from 2.5-32.5% by volume of said thermoplastic adhesive wherein substantially surrounds each said filaments.
Dependencies are inferred from the claim text.