Importance

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Abstract

The invention is a method for sizing polyterafluoroethylene fibers, yarns, or threads comprising: (a) contacting polytetrafluoroethylene fibers, yarns, or threads with a sizing composition of a perfluorinated polymer containing sites convertible to ion exchange groups and a treating agent having: a boiling point less than about 110.degree. C.; a density of from about 1.55 to about 2.97 grams per cubic centimeter; and a solubility parameter of from greater than about 7.1 to about 8.2 hildebrands; and (b) removing the treating agent from the sizing composition, thereby depositing the perfluorinated polymer onto the surface of the polytetrafluoroethylene. Particularly preferred as a treating agent is a compound represented by the general formula: XCF.sub.2 --CYZX' wherein: X is selected from the group consisting of --F, --Cl, --Br, and --I; X' is selected from the group consisting of --Cl, --Br, and --I; Y and Z are independently selected from the group consisting of --H, --F, --Cl, --Br, --I and --R'; R' is selected from the group of perfluoroalkyl radicals and chloroperfluoroalkyl radicals having from 1 to 6 carbon atoms. The most preferred treating agent is 1,2-di-bromotetrafluoroethane.

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First Claim