Extruder screw with alternately-arranged conveyance portions and extruders and extrusion methods using the extruder screw

An extruder screw comprising:

• a transfer portion continuously conveying supplied materials;
• a melting and mixing portion continuously melting and mixing the conveyed materials;
• and
• a kneading portion continuously kneading raw materials obtained by melting and mixing the materials,
• wherein
• the transfer portion, the melting and mixing portion, and the kneading portion are provided in a screw main body rotating about a straight axis,
• a part of the screw main body in which the kneading portion is provided is composed of a plurality of cylindrical bodies and a rotating shaft supporting the plurality of cylindrical bodies and rotating about the axis,
• 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,
• each of the barrier portions includes a path provided across the two conveyance portions disposed adjacent to both sides of the barrier portion and inside the cylindrical body of the barrier portion, the path comprising an entrance and an exit,
• the entrance is opened in an outer circumferential surface of the cylindrical body in the conveyance portion adjacent to the barrier portion to urge the raw materials, having the conveyance limited by the barrier portion from a proximal end side of the screw main body to increase pressure on the raw materials, to flow into the entrance,
• the path is configured to urge the raw materials flowing from the entrance to flow toward the exit in a same direction as a direction of the conveyance of the conveyance portion, and
• the exit is opened in the circumferential surface of the cylindrical body in the conveyance portion adjacent to the barrier portion from a distal end side of the screw main body.