Porous composite membrane and process
First Claim
1. A composite porous membrane which comprises a porous membrane substrate having an average pore size of between about 0.01 and 10 microns formed of a first polymer, said substrate having directly deposited over its entire surface a self-crosslinked second polymer free of a crosslinking agent and being formed from at least one uncrosslinked, self-crosslinkable polymer and a free radical initiator free of a crosslinking agent, said composite porous membrane having essentially the same porous configuration as said porous membrane substrate.
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Abstract
A composite porous membrane is provided which comprises a porous membrane substrate having an average pore size between 0.01 and 10 microns formed of a first polymer which is coated over its entire surface with a crosslinked second polymer. The second polymer is dissolved in a solvent with a free radical polymerization initiator in the absence of a crosslinking agent. The second polymer is crosslinked in situ and rendered insoluble by mild heating and/or exposure to ultraviolet light.
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Citations
37 Claims
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1. A composite porous membrane which comprises a porous membrane substrate having an average pore size of between about 0.01 and 10 microns formed of a first polymer, said substrate having directly deposited over its entire surface a self-crosslinked second polymer free of a crosslinking agent and being formed from at least one uncrosslinked, self-crosslinkable polymer and a free radical initiator free of a crosslinking agent, said composite porous membrane having essentially the same porous configuration as said porous membrane substrate.
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2. The composite porous membrane of claim 1 wherein said self crosslinked second polymer is derived from a hydrophilic polymer deposited on said substrate from an aqueous solution.
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3. The composite porous membrane of any one of claims 1 or 2 wherein said substrate has an average pore size between about 0.05 and 5 microns.
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4. The composite porous membrane of any one of claims 1 or 2 wherein said substrate has an average pore size between 0.1 and 1.0 microns.
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5. The composite porous membrane of claim 1 in the form of a flat sheet.
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6. The composite porous membrane of claim 2 in the form of a flat sheet.
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7. The composite porous membrane of claim 1 in the form of a hollow fiber.
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8. The composite porous membrane of claim 2 in the form of a hollow fiber.
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9. The composite porous membrane of any one of claims 1, 2, 3, 4, 5, 6, 7 or 8 wherein said self crosslinked second polymer is a crosslinked polymer containing hydroxyl groups.
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10. The composite porous membrane of claim 9 wherein said self crosslinked second polymer is a crosslinked polyvinyl alcohol.
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11. The composite porous membrane of any one of claims 1, 2, 3, 4, 5, 6, 7 or 8 wherein said self crosslinked second polymer is a crosslinked polymer containing nitrogen.
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12. The composite porous membrane of claim 11 wherein said self crosslinked second polymer is a crosslinked polyvinylpyrrolidone.
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13. The composite porous membrane of claim 11 wherein said self crosslinked second polymer is a crosslinked polyacrylamide.
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14. The composite porous membrane of claim 11 wherein said self crosslinked second polymer is a crosslinked polyvinyl amine.
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15. The composite porous membrane of any one of claims 1, 2, 3, 4, 5, 6, 7 or 8 wherein said self crosslinked second polymer is a crosslinked polymer containing carboxyl groups.
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16. The composite porous membrane of claim 15 wherein said self crosslinked second polymer is a crosslinked polyacrylic acid.
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17. The composite porous membrane of claim 15 wherein said self crosslinked second polymer is a crosslinked polymethacrylic acid.
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18. The composite porous membrane of any one of claims 1, 2, 3, 4, 5, 6, 7 or 8 wherein said self crosslinked second polymer comprises a crosslinked polymer containing sulfonic acid groups and/or phosphonic acid groups.
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19. The composite porous composition of any one of claims 1, 2, 3, 4, 5, 6, 7 or 8 wherein said self crosslinked second polymer includes at least one additional polymerized monomer.
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20. The composite porous membrane of claim 19 wherein said monomer comprises a sulfonic acid or a phosphonic acid.
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21. The composite porous membrane of claim 19 wherein said monomer is diallyldimethylammonium chloride.
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22. The composite porous membrane of claim 19 wherein said monomer is acrylic acid.
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23. The composite porous membrane of claim 19 wherein said monomer is methacrylic acid.
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24. The composite porous membrane of any of the claims 1, 2, 5, 6, 7, or 8 wherein said first polymer is a halogenated hydrocarbon polymer.
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25. The composite porous membrane of claim 24 wherein said first polymer is a fluorinated hydrocarbon polymer.
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26. The composite porous membrane of claim 25 wherein said first polymer is a polyvinylidene fluoride polymer.
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27. The composite porous membrane of claim 25 wherein said first polymer is a polytetrafluoroethylene polymer.
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28. The composite porous membrane of any one of claims 1, 2, 3, 4, 5, 6, 7, or 8 wherein said first polymer is a perfluoroalkoxy resin.
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29. The composite porous membrane of claim 24 wherein said first polymer is polyvinyl chloride.
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30. The composite porous membrane of any one of claims 1, 2, 5, 6, 7, or 8 wherein said first polymer is a nitrogen containing polymer.
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31. The composite porous membrane of claim 30 wherein said first polymer is a polyamide.
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32. The composite porous membrane of any of the claims 1, 2, 5, 6, 7 or 8 wherein said first polymer is an olefin polymer.
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33. The composite porous membrane of claim 32 wherein said first polymer is polyethylene.
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34. The composite porous membrane of claim 32 wherein said first polymer is polypropylene.
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35. The composite porous membrane of any of the claims 1, 2, 5, 6, 7 or 8 wherein said first polymer is a polysulfone polymer.
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36. The composite porous membrane of claim 35 wherein said first polymer is polyethersulfone.
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37. The composition of any one of claims 1, 2, 5, 6, 7 or 8 wherein said polymerization initiator comprises a persulfate.
Specification