Microporous hollow fiber membranes from perfluorinated thermoplastic polymers
AssigneeMykrolis Corporation
InventorsKwok-Shun Cheng, Rajnikant B. Patel, T. Dean Gates
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Abstract
High flux porous hollow fiber membranes are produced from perfluorinated thermoplastic polymers by extruding a heated solution of the polymer having a lower critical solution temperature directly into a cooling bath to form the porous membrane by liquid-liquid phase separation. Extrusion can be conducted either vertically or horizontally.
Claims29
A hollow fiber porous membrane made of a perfluorinated thermoplastic polymer having an essentially skinless surface on at least one surface and an IPA flow time of less than about 3000 seconds.
A method of producing a hollow fiber porous membrane from a perfluorinated thermoplastic polymer having an essentially skinless surface on at least one surface comprising;
- a) dissolving said perfluorinated thermoplastic polymer in a solvent that forms an upper critical solution temperature solution with said polymer,
- b) extruding said solution through an annular die, a portion of said die being submerged in a cooling bath, and maintained at a temperature sufficiently high to prevent said solution from prematurely cooling,
- c) extruding said solution into said cooling bath,
- d) cooling said solution to below the upper critical solution temperature to cause separation into two phases by liquid-liquid phase separation, said phases being a polymer rich solid phase, and a solvent rich liquid phase, to form a gel fiber,
- e) extracting said solvent from said gel fiber to form a porous hollow fiber membrane,
- f) drying said porous hollow fiber membrane under restraint.
A hollow fiber contactor membrane made of a perfluorinated thermoplastic comprising a porous surface on both diameters.
A hollow fiber contactor membrane made of perfluorinated thermoplastic comprising a unskinned surface both diameters capable of liquid-gas mass transfer with a Sherwood number equal to about 1.64 times the Graetz number to the 0.33 power in a range of Graetz numbers of from about 5 to about 1000.
Dependencies are inferred from the claim text.