Expandable TFE copolymers, method of making, and porous, expended articles thereof
First Claim
Patent Images
1. An expandable core-shell tetrafluoroethylene (TFE) copolymer comprising:
- (a) a first, core portion comprising a polymer chain of TFE monomers and at least one comonomer, said comonomer being an ethylenically unsaturated comonomer; and
(b) a second, shell portion consisting of a polymer chain consisting of TFE monomers,wherein said expandable core-shell tetrafluoroethylene copolymer comprises at least 3.0% by weight polymerized units of said at least one comonomer based on total weight of said copolymer.
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Abstract
A process for the polymerization of a true tetrafluoroethylene (TFE) copolymer of the fine powder type is provided, wherein the copolymer contains polymerized comonomer units of at least one comonomer other than TFE in concentrations of at least or exceeding 1.0 weight percent, and which can exceed 5.0 weight percent, wherein the copolymer is expandable, that is, the copolymer may be expanded to produce strong, useful, expanded TFE copolymeric articles having a microstructure of nodes interconnected by fibrils.
235 Citations
36 Claims
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1. An expandable core-shell tetrafluoroethylene (TFE) copolymer comprising:
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(a) a first, core portion comprising a polymer chain of TFE monomers and at least one comonomer, said comonomer being an ethylenically unsaturated comonomer; and (b) a second, shell portion consisting of a polymer chain consisting of TFE monomers, wherein said expandable core-shell tetrafluoroethylene copolymer comprises at least 3.0% by weight polymerized units of said at least one comonomer based on total weight of said copolymer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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34. A paste extrudable and expandable core-shell tetrafluoroethylene (TFE) copolymer of the fine powder type comprising:
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(a) a first, core portion comprising a polymer chain of TFE monomers and at least one comonomer, said comonomer being an ethylenically unsaturated comonomer; and (b) a second, shell portion consisting of a polymer chain consisting of TFE monomers, wherein said paste extrudable and expandable core-shell tetrafluoroethylene copolymer comprises greater than 3.0% by weight, polymerized monomer units of said at least one comonomer, based on total weight of copolymer. - View Dependent Claims (35)
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36. An expandable core-shell tetrafluoroethylene (TFE) copolymer comprising:
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(1) a first, core portion comprising a polymer chain of TFE monomers and at least one comonomer, said comonomer being an ethylenically unsaturated comonomer; and (2) a second, shell portion consisting of a polymer chain consisting of TFE monomers, wherein said expandable core-shell tetrafluoroethylene copolymer comprises less than 95.0% by weight polymerized tetrafluoroethylene (TFE) monomer units and greater than 5.0% by weight polymerized monomer units of said at least one comonomer based on total weight of polymer and produced by the following process; (a) copolymerizing said TFE monomer and said at least one comonomer in a pressurized reactor by feeding less than 95.0% by weight of said TFE monomer into said pressurized reactor and feeding greater than 5.0% by weight of said at least one comonomer into said pressurized reactor, wherein percentages are based upon total weight of monomers fed, (b) initiating polymerization of said TFE monomers and said at least one comonomer with a free radical initiator, and (c) stopping the feeding of said at least one comonomer prior to completion of the polymerization reaction, and, optionally, (d) removing excess said at least one comonomer from said reactor prior to completion of polymerization.
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Specification