Melt‐spinning process of a tetrafluoroethylene– hexafluoropropylene copolymer

Abstract

An industrial melt-spinning process of tetrafluoroethylene-hexafluoropropylene copolymer (FEP) using an extruder was studied. The novel "spinneret," having both a large-diameter spinning nozzle and a high-temperature vessel, was used to solve the problem of filament breakage on the spinning line caused by high melting viscosity of FEP. The extruder, with its long feed zone, was newly designed to function with a geared pump. The strength of fibers increased with drawing of as-spun fiber. FEP fibers up to six denier were continuously produced through long-run production. According to this new process, FEP fibers can be supplied for textile or industrial application.

Melt-spun poly(tetrafluoroethylene) fibers

“…The air inside the chamber reached the temperature at half height. A similar setup was used by Uno et al [4] for melt-spinning of fluorinated ethylene-propylene copolymer (FEP) fibers. Two spinnerets of different entrance angles and orifice lengths were used.…”

“…A drawback of the latter fibers, however, is their relatively high linear density, which is 38 tex for Gore TM Rastex Ò 4300, i.e. more than 40 times higher than that of melt-spun FEP, PFA and PTFE fibers of~1 tex [4,20]. In addition, melt-spun fibers have a highly regular cross-section and a smooth surface.…”

“…These processes include the split-peel process (i.e. skiving from sintered preforms, which may take 48 h or more to produce), matrix spinning followed by sintering of PTFE and removal of the matrix material, and paste extrusion and sintering of the polymer [2][3][4]. The mechanical properties of the asproduced fibers most often are improved by subsequent tensile drawing techniques [see also 5,6].…”

Study on vacuum membrane distillation (VMD) using FEP hollow fiber membrane

“…Currently, polypropylene (PP) and polyvinylidenefluoride (PVDF) are the most common membrane materials used in the MD process [9][10][11] which are prepared through the phase inversion method or the melting spinning-stretching method (M-S) [12][13][14]. However, as for some MD processes with harsh water environments (high temperature, containing acid or alkali, and organic solvents), PVDF and PP are impossible to be used.…”

Fabrication and properties of poly(tetrafluoroethylene-co-hexafluoropropylene) hollow fiber membranes

“…To overcome these poor processing properties, many researchers have focused on tetrafluoroethylene copolymers to improve the melting properties of PTFE. [19][20][21][22] Common second monomers are hexafluoropropylene, perfluoroalkyl vinylether, and so on. Several past attempts to fabricate polytetrafluoroethylene-co-hexafluoropropylene (FEP) membranes can be found in the patent literature.…”