Manufacturing cylindrical pipes formed of PTFE and PTFE recyclate

摘要

A process for the production of a cylindrical hollow article (1) formed of polytetrafluoroethylene (PTFE) or recycled PTFE is claimed. (1) is formed by pressing and sintering a significant portion (L1) of its length (L2) consisting of PTFE or recycled PTFE and having a disk shaped end portion (2) consisting of a weldable polymer, preferably a modified PTFE to form a compact cylindrical blank(3). The length (L2) of (3) corresponds to the circumference of (1). A film like layer (5) is peeled away from (3) and has a thickness (D) and length (L3) that corresponds to the wall thickness (WD) and length (L) of the hollow article (1). The layer (5) is formed into a pipe (8,8a) having a slot (10,10a) with borders (6) formed of the weldable polymer. The borders (6) are heated and welded togethr to form an overlapping or butt joint followed by cooling under pressure.