Abstract: A screw has a spiral blade for extruding and kneading a high-silica plastic elastomer containing not less than 100 phr of silica. The screw has a first section located on the most downstream side in the extrusion direction and provided with a barrier extending between the adjacent spiral blade threads, while inclining with respect to the screw axial direction. The length of the barrier is 1.5 to 3.0 times the lead length of the spiral blade in the first section. The height of the barrier is 2 to 10 mm lower than the height of the spiral blade. The barrier thickness is 0.9 to 3.0 times the height difference between the spiral blade and barrier.

Abstract: A screw with a spiral blade for extruding a plastic elastomer while kneading the plastic elastomer, the screw includes a kneading region where the spiral blade is provided with cutout portions being configured to pass pins, and a plasticizing region being arranged on a downstream side in an extrusion direction of the kneading region. The plasticizing region includes a barrier extending between portions adjacently in the extrusion direction of the spiral blade.

Abstract: To provide a rubber extruder capable of efficiently removing volatile components in unvulcanized rubber without decreasing productivity of the unvulcanized rubber. The rubber extruder 1 is for extruding the unvulcanized rubber (G) while kneading. It includes a barrel 2 having an input port 5 for introducing the unvulcanized rubber (G) and a discharge port 6 for discharging the unvulcanized rubber (G), a screw 3, which is arranged in the barrel 2, for extruding the unvulcanized rubber (G), and a vent 4 for sucking out air in the barrel 2. The screw 3 has a dam portion 7 which locally controls an extrusion amount of the unvulcanized rubber (G), a first screw portion 8 defined between the input port 5 and the dam portion 7, and a second screw portion 9 defined between the dam portion 7 and the discharge port 6. An effective screw length (L1) of the first screw portion 8 is 50% or more of a total effective screw length (L) of the screw 3.