Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1991-08-01
1996-09-24
Choi, Kathleen L.
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
428395, 428398, 21050023, 21050039, 210506, 96 14, D02G 302, B01D 3900, B01D 6302
Patent
active
055589367
ABSTRACT:
PVP-coated asymmetric hollow fibers made from SIXEFT.TM.-Durene, a polyimide made from 2,2-bis[3,4-dicarboxyphenyl] hexafluoropropane dianhydride and 2,3,5,6-tetramethylphenylene diamine monomers, and a process for making such fibers. These coated fibers have a separation factor that exceeds 6 for oxygen and nitrogen and a permeance of at least about 10 ppm cc(STP)/(sec cm.sup.2 cm-Hg). A polymer dope comprising SIXEF.TM.-Durene in a solvent system containing N-methyl-2-pyrrolidone ("NMP") and an organic acid such as propionic acid ("PA") is prepared by polymerizing the polyimide monomers in NMP to form a polyamic acid polymer and imidizing this polymer using the acid anhydride. Water released from the polymer in the imidization reaction converts the anhydride to acid. The dope is wet-spun into hollow fibers; the fibers are coagulated in water. The fibers are then evenly coated with PVP, preferably by dipping the fibers in a dilute PVP solution.
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Chung Tai-Shung
Kafchinski Edward R.
Choi Kathleen L.
Ferrell Michael W.
Hoechst Celanese Corp
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