| 摘要 |
836,024. Extruding polytetrafluoroethylene. RAYBESTOS-MANHATTAN Inc. Aug. 9, 1956 [Aug. 18, 1955], No. 24399/56. Class 87(2). Extruded polytetrafluoroethylene tubing 3 is passed downwardly through a vertical tower 1 where inflammable lubricant, e.g. naptha, is removed in a zone 4 by blowing a hot inert gas, e.g. nitrogen, carbon dioxide, superheated steam or flue gases, through an inlet 8 and upwardly through the tower and out at exit 10. To prevent excessive volatilization of the lubricant, the hot gas may be cooled by a coil 14. Air is prevented from entering the tower by providing a water trap 11 at the exit from the tower. Any air entering at the upper end of the tower is withdrawn at the exit 10 and may provide a cooling effect. The material is sintered in zone 5 by radiant heat from a heater 6 surrounded by an insulating jacket 7. After sintering, the hot gas acts to provide a soaking zone 13. In order to limit the growth of crystallinity in the material, it may be partly and suddenly cooled by a water spray 17. In order that the tube may be sufficiently flexible for the bend of the water trap, some of the hot gas may be drawn downwardly by a blower 21 to heat this portion of the material. In a modification, the trap may be replaced by a gasket and the blower 21 used to draw off any air that leaks through the gasket. Alternatively the material can be collected within the bottom of the chamber 19 on a reel and emptied at the end of a run. |
