SINGLE-SHAFT SCREW TYPE EXTRUSION MACHINE OR DOUBLE-SHAFT SCREW TYPE EXTRUSION MACHINE FOR BLEEDING GAS FROM THERMOPLASTIC RESIN MELT

摘要

PURPOSE: To obtain a good degassed product without making the structure or manufacture of the subject extruder expensive by providing a disc having a specific thickness and a profile on a back portion of the disc directed toward an inner cylinder of an extruder. CONSTITUTION: Discs 5 each having a thickness of 0.1 to 0.5 D (D is a diameter of a screw) are alternately provided at spacer members 6 at a lower side of a degassing port 4. Intermediate spaces 16 to 22 are opened between the discs 5 and the members 6. A melt to be degassed is fed from screws 12, 13 to, for example, the space 16, and then arrived at next space 17 at opposed side. In a next lapse, the melt is fed to the spaces 18 to 22 via a groove 9 and the back part 15 of the disc. Accordingly, it is reciprocatingly conveyed from the disc on one coupling rod 14 to the disc provided on adjacent coupling rod 13 and hence a very thin melt layer is formed. Gaseous monomer residue and the like are removed from these layers.