Dual-screw extruder removing volatile liquids from thermoplastic melt

摘要

The extrusion unit volatilises liquids in thermoplastic melts. It comprises an extruder cylinder having openings for water injection and subsequent venting. In the cylinder, the dual screws rotate in the same direction, in engagement. The filling zone (10) is followed by a water injection and distribution zone (11). In the expansion zone (17), the pressure is let down, ahead of the evaporation zone (12) and vent opening. A ring (15) is located downstream of the water injection opening into the distribution zone. There is at least one water injection and distribution zone. Also claimed is the corresponding process, in which the water is injected in the kneading zone of the extruder, and in which the injected water removes fluid components from the molten polymer.