Patent ID: 6068466
Filing Date: 2000-05-30
Classification: B29C

Abstract:
A twin shaft continuous kneading extruder comprising:a twin kneading feeder portion provided with two passage portions juxtaposed to each other within a casing and having a cocoon-shape in cross-section, in which a first kneading shaft and a second kneading shaft are rotatably disposed in the respective passage portions, said casing having innerwalls that define said two passage portions, said twin kneading feeder portion having a final end portion and a feeding end portion at ends of said passage portions;single screw portion substantially extending one of said passage portions within the casing, and having a screw disposed within said single screw portion and substantially extending said first kneading shaft;a material feeding port provided at said feeding end portion of the casing for feeding resin material to said twin kneading feeder portion;a discharge port provided in the casing for discharging kneaded resin material from an end portion of said single screw portion;a plurality of mixing portions provided in said twin kneading feeder portion and including mixing rotors on said first kneading shaft and said second kneading shaft, and a gap defined between said mixing rotors and said innerwalls of said casing, said gap having a varying first width either smaller toward said final end portion of said twin kneading feeder portion than the first width at said feeding end portion of said twin kneading feeder portion when the viscosity of said resin material is lowered in the process of melting said resin material or said first width of the gap is larger toward said final end portion of said twin kneading feeder portion than the first width at said feeding end portion when the viscosity of said resin material is increased in the process of melting the resin material;a first degassing open vent provided in the casing for communicating with at least one mixing portion of the plurality of mixing portions and said kneading shafts within said one mixing portion; anda second vacuum degassing open vent provided in communication with an interior of the casing at a predetermined position of said single screw portion;wherein said twin kneading feeder portion semi-gels, melts, kneads and degasses said resin material fed from said material feeding port, and said single screw portion vacuum degasses and extrudes said resin material.