Perfluorinated thermoplastic filter cartridge
View Patent ↗A filtration cartridge having a housing with an inlet and an outlet and a filtration membrane contained within the housing and located between the inlet and the outlet is described. The membrane is sealed in such a manner that all fluid must flow through the membrane between entering the inlet and leaving the outlet of the housing. The entire cartridge, housing, membrane and any other components are all formed of one or more perfluorinated thermoplastic resins. These resins preferably are PFA, MFA, FEP and blends thereof. The membrane may be in the form of hollow fibers, wound fibers such as in a depth filter, or a flat sheet which may be formed into various configurations such as spiral filters, pleated filters, spiral pleated filters, disks and the like. These cartridges provide an inert, high temperature and acid/oxidative chemical resistant filter having properties similar to that of PTFE resins.
1. A perfluorinated thermoplastic resin filtration cartridge comprising:
a housing having an inlet and an outlet; and
one or more membrane filters located between the inlet and the outlet;
sealing means forming a liquid-tight seal between the one or more membrane filters and the outlet;
such that an integral filtration device is formed, wherein all fluid must pass through the one or more membrane filters from the inlet to the outlet;
wherein the seal and the one or more membrane filters are formed of perfluorinated thermoplastic resins,
said membrane formed by thermally induced phase separation from perfluorinated thermoplastic resins,
said resins being selected from the group consisting of poly(tetrafluoroethylene-co-perfluoro(alkylvinylether)), poly(tetrafluoroethylene-co-hexafluoropropylene)) and blends thereof; and
wherein the sealing means has a melting point equal to or less than that of the membrane filter resins;
wherein the membrane is a depth filter formed of one or more wound fibers.
2. The cartridge of claim 1 , wherein the perfluorinated thermoplastic polymer is poly(tetrafluororethylene)-co-perfluoro(alkylvinylether)) and the alkyl is selected from the group consisting of propyl, methyl and blends of propyl and methyl.
3. The filter cartridge of claim 1 , wherein the filter cartridge comprises a cylindrical form.
4. The filter cartridge of claim 1 , wherein the liquid tight seal prevents fluid entering the housing from mixing with filtered fluid exiting the housing.
5. The filter cartridge of claim 1 , wherein the potting material has a lower melting temperature than the melting or softening temperature of the material used to make the membrane.
6. The filter cartridge of claim 5 , wherein the melting or softening temperature of the potting material is at least about 5° C. lower than the melting temperature of the material used to make the membrane.
7. The filter cartridge of claim 5 , wherein the melting temperature of the seal material is at least about 10° C. lower than the melting or softening temperature of the material used to make the membrane.
8. The filter cartridge of claim 1 , further comprising one or more end caps for the housing wherein the end caps are formed of perfluorinated thermoplastic resin.
9. The filter cartridge of claim 8 , wherein each end cap is liquid tightly joined to an end of the housing.
10. The filter cartridge of claim 9 , wherein the end caps and the housing form a unitary end structure.
11. The filter cartridge of claim 1 , wherein the membrane further comprises in combination a microporous membrane.
12. The filter cartridge of claim 1 , wherein the membrane further comprises in combination an ultrafiltration membrane.
13. The filter cartridge of claim 1 , wherein the perfluorinated thermoplastic resin is poly(TFE-co-PFAVE).
14. The filter cartridge of claim 1 , wherein the perfluorinated thermoplastic resin is selected from the group consisting of poly(tetrafluoroethylene-co-perfluoro(alkylvinylether)), poly(tetrafluoroethylene-co-hexafluoropropylene), and blends thereof.