Patent ID: 8177412

Claim:
A method of kneading a rubber-based composition comprising rubber and compounding ingredients using a kneading apparatus comprising a barrel having a cylindrical chamber; a screw assembly rotating in the chamber for extruding a material to be kneaded in the axial direction, said screw assembly comprising a screw section having helical blades and a kneading blade section for allowing the material to flow into the clearance between the inner wall of the chamber and a kneading blade of said kneading blade section, and for applying shearing forces to the material to be kneaded; a metering feeder for feeding the material at a substantially constant volumetric rate or at a substantially constant gravimetric rate from a feed port provided on the barrel into the chamber; an injecting device provided on the barrel for injecting a heat-removing medium into the chamber; a dewatering device that separates the heat-removing medium in a liquid state from the material by subjecting the rubber-based composition to a filling and compressing action; and a discharging device for separating the heat-removing medium in a vapor state from the material, wherein the heat-removing medium has been injected into the chamber by said injecting device and mixed with the material, and discharging the heat-removing medium from the chamber, the method comprising: a feeding step of feeding the rubber-based composition into the chamber of the kneading apparatus at a substantially constant volumetric rate or at a substantially constant gravimetric rate by the metering feeder, wherein the rubber-based composition has a Mooney viscosity at 100° C. of not less than 100; a kneading step of allowing the rubber-based composition to flow into the clearance between the inner wall of the chamber and the kneading blade section and moving the rubber-based composition in the chamber while mixing and dispersing the rubber-based composition by means of shearing forces; a mixing step of injecting a liquid heat-removing medium into the chamber by the injecting device and mixing the rubber-based composition with the heat-removing medium before or during kneading, sufficient to maintain the temperature of the rubber-based composition at 160° C. or less during kneading; a dewatering step of separating the heat-removing medium in a liquid state from the rubber-based composition by the dewatering device by subjecting the rubber-based composition to a filling and compressing action; and a discharging step of discharging the separated heat-removing medium in a vapor state by the discharging device provided at the location in the axial direction of the dewatering device.