Extruder screw including conveyance portions and paths within the conveyance portions, extruder, and extrusion method

An extruder screw comprising:

• in order from a proximal end of the extruder screw to a distal end thereof:
• a transfer portion configured to continuously convey supplied materials;
• a melting and mixing portion configured to continuously melt and mix the conveyed materials;
• and
• a kneading portion configured to continuously knead a raw material obtained by melting and mixing the materials, wherein
• the transfer portion, the melting and mixing portion, and the kneading portion are provided on a screw main body rotating around a linear axis line,
• a part of the screw main body in which the kneading portion is provided is composed of a rotating shaft, coaxially extending from a portion in which the melting and mixing portion is provided, and a plurality of cylindrical bodies fitted and supported in the rotating shaft,
• a plurality of conveyance portions conveying the raw materials and a plurality of barrier portions limiting conveyance of the raw materials are alternately arranged on the plurality of cylindrical bodies coaxially connected along the rotating shaft,
• a path is provided in each of the plurality of conveyance portions, inside each of the cylindrical bodies, and includes an entrance and an exit,
• the entrance is opened at an outer circumferential surface of the cylindrical body of a distal end side at the conveyance portion in such a manner that the raw material pressure of which is enhanced by being restricted in conveyance by the barrier portion flows into the entrance,
• the path is formed in such a manner that the raw material flowing into the path from the entrance flows toward the exit in a direction opposite to the direction of conveyance carried out by the conveyance portion, and
• the exit is opened on the circumferential surface of the cylindrical body of a proximal end side in the conveyance portion.