Patent ID: 8899820

Claim:
A melting kneading devolatilizing extruder, comprising: a cylinder; two screws rotatably inserted into a bore of the cylinder, wherein each screw is configured to receive resin raw material supplied from outside the cylinder to an upstream portion of the screw, to knead and to devolatilize the resin raw material at a region of the screw that is downstream from the upstream portion, and to convey the resin raw material to a downstream portion, wherein the screw comprises at least one surface renewable screw segment, each of which includes a plurality of discs that are arrayed such that a phase angle E, which is a deviation angle between the discs around an axis of the screw, is 0°<E<90°, and wherein the surface renewable screw segment comprises void portions disposed between the discs so that the discs are arranged at intervals in a direction of the axis of the screw and spaced apart from each other due to the void portions interposed between adjacent ones of the discs, where each of the void portions is a ring-shaped member having an external diameter equal to or less than a short diameter of the discs, and wherein the void portion of the surface renewable segment has a ratio of 0<L/D≦0.02, where L is the length of an individual one of the void portions and D is the diameter of the cylinder bore; the screw includes an upstream seal portion; and a vent is provided for reducing a pressure in the cylinder, wherein the upstream seal portion, the surface renewable segment and the vent are arranged in this order from the upstream portion to the downstream portion of the screw.