Stable tetrafluoroethylene copolymers
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First Claim
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1. A melt-fabricable, nonelastomeric, copolymer of recurring units of tetrafluoroethylene, between about 1 and 10 weight percent units of at least one perfluoro(alkyl vinyl)ether where the alkyl group contains 1-8 carbon atoms, which can contain up to about 5 weight percent units of a comonomer selected from the formula ##STR3## wherein R1 is --Rf or --Rf X in which Rf is a perfluoroalkyl radical of 1-12 carbon atoms, and X is H or Cl;
- and R2 is --Rf or --Rf --X, where --Rf -- is a perfluoroalkylene diradical of 1-12 carbon atoms in which the attaching valences are at each end of the chain, which copolymer is substantially free of end groups that can react or decompose to emit HF, said copolymer characterized by having(a) less than 6 endgroups of --CF2 CH2 OH, --CONH2 and --COF per 106 carbon atoms and(b) an extractable fluoride level of 3 ppm or less by weight.
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Abstract
A tetrafluoroethylene/perfluoro(alkyl vinyl)ether copolymer substantially free of unstable end groups and extractable fluoride that cause corrosion of metal surfaces.
243 Citations
5 Claims
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1. A melt-fabricable, nonelastomeric, copolymer of recurring units of tetrafluoroethylene, between about 1 and 10 weight percent units of at least one perfluoro(alkyl vinyl)ether where the alkyl group contains 1-8 carbon atoms, which can contain up to about 5 weight percent units of a comonomer selected from the formula ##STR3## wherein R1 is --Rf or --Rf X in which Rf is a perfluoroalkyl radical of 1-12 carbon atoms, and X is H or Cl;
- and R2 is --Rf or --Rf --X, where --Rf -- is a perfluoroalkylene diradical of 1-12 carbon atoms in which the attaching valences are at each end of the chain, which copolymer is substantially free of end groups that can react or decompose to emit HF, said copolymer characterized by having
(a) less than 6 endgroups of --CF2 CH2 OH, --CONH2 and --COF per 106 carbon atoms and (b) an extractable fluoride level of 3 ppm or less by weight. - View Dependent Claims (3, 4, 5)
- and R2 is --Rf or --Rf --X, where --Rf -- is a perfluoroalkylene diradical of 1-12 carbon atoms in which the attaching valences are at each end of the chain, which copolymer is substantially free of end groups that can react or decompose to emit HF, said copolymer characterized by having
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2. A process for removing unstable end groups and extractable fluoride content from a copolymer of recurring units of tetrafluoroethylene, between about 1 and 10 weight percent units of at least one perfluoro(alkyl vinyl)ether where the alkyl group contains 1-8 carbon atoms, which can contain up to about 5 weight percent units of a comonomer selected from the formula ##STR4## wherein R1 is --Rf or --Ff X in which Rf is a perfluoroalkyl radical of 1-12 carbon atoms, and X is H or Cl;
- and R2 is --Rf or --Rf --X, where --Rf -- is a perfluoroalkylene diradical of 1-12 carbon atoms in which the attaching valences are at each end of the chain, which copolymer contains more than 6 per 106 carbon atoms of end groups of --CF2 CH2 OH, --CONH2 and --COF, which comprises;
(a) contacting the copolymer with a fluorine-containing gas at a temperature, time and pressure sufficient to reduce the unstable end groups --CF2 CH2 OH, --CONH2 and --COF to less than 6 per 106 carbon atoms, and (b) sparging the fluorinated copolymer with an inert gas until the level of extractable fluoride is 3 ppm or less by weight.
- and R2 is --Rf or --Rf --X, where --Rf -- is a perfluoroalkylene diradical of 1-12 carbon atoms in which the attaching valences are at each end of the chain, which copolymer contains more than 6 per 106 carbon atoms of end groups of --CF2 CH2 OH, --CONH2 and --COF, which comprises;
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Litigation Data
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Current AssigneeE. I. du Pont de Nemours and Company (Corteva, Inc.)
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Original AssigneeE. I. du Pont de Nemours and Company (Corteva, Inc.)
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InventorsKerbow, Dewey L., Imbalzano, John F.
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Primary Examiner(s)Schofer, Joseph L.
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Assistant Examiner(s)Teskin, F. M.
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Application NumberUS06/789,893Time in Patent Office932 DaysField of Search525/326.4, 525/326.2, 525/355, 525/356, 526/247, 264/83US Class Current525/326.4CPC Class CodesB29B 9/16 Auxiliary treatment of gran...B29K 2027/12 containing fluorineC08F 214/26 TetrafluoroetheneC08F 214/262 with fluorinated vinyl ethersC08F 216/1408 Monomers containing halogenC08F 8/22 by reaction with free halogens
