Kneading method for use with kneading apparatus with first and second extruders

A kneading method comprising:

• continuously melting and mixing materials in a processor to form melted materials;
• and
• using the melted materials as raw materials and continuously discharging kneaded materials produced by kneading the raw materials with a screw in an extruder, wherein
• the screw comprises a screw main body configured to rotate on a straight axial line in a conveyance direction of the raw materials such that tubes are coaxially joined to an axis of rotation whereby each of the tubes and the axis of the rotation are integrally assembled to form the screw,
• in the screw main body, a conveyance portion configured to convey the raw materials, a barrier portion configured to limit conveyance of the raw materials, and a plurality of paths through which raw materials flow are provided at places in a direction of the axial line, and the plurality of paths are arranged in a circumferential direction of the screw main body at intervals,
• each of the plurality of paths is provided inside each respective one of the tubes, and each of the plurality of paths comprises an entrance, an exit, and path main body communicating between the entrance and the exit,
• the entrance is opened in an outer circumferential surface of the tube in the conveyance portion to cause the raw materials, the conveyance of which is limited by the barrier portion to increase pressure on the raw materials, to flow in the entrance,
• each of plurality of paths is respectively configured to allow the raw materials to flow in from the entrance, pass through the path main body, and flow out of the exit,
• the exit is opened in the outer circumferential surface of the tube at a position remote from the entrance in a direction of the axial line,
• in the extruder, the raw materials conveyed along an outer circumferential surface of the screw main body flow through the paths and then return to an outer circumferential surface of the screw, while the kneaded materials are continuously discharged,
• conveyance of the raw materials conveyed along the outer circumferential surface of the screw main body is limited by the barrier portion provided on the screw main body to increase pressure on the raw materials, and
• the raw materials, the pressure on which is increased by the barrier portion, are made to flow into the paths from the outer circumferential surface of the screw main body.