| 摘要 |
1,004,406. Extruding plastics tubing. BTR. INDUSTRIES Ltd. Oct. 23, 1963 [Oct. 29, 1962], No. 40812/62. Heading B5A. Polytetrafluoroethylene tubing is manufactured by preforming a polytetrafluorethylene composition by compression in a chamber, extruding a solid rod from the preformed material, coiling the rod formed around a central pin within the compression chamber of a conventional extruder and extruding the tube which is then sintered. Preferably, the extruded rod is passed through a bath of solvent, e.g. naphtha, before it is introduced into the compression chamber. In an alternative process the extruded rod may be coiled around a central pin a secured preforming chamber, compressed and then introduced into the compression chamber of the extruder.
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