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Assignee3M Innovative Properties Company
InventorsWerner M. A. Grootaert, Klaus Hintzer, Bernhard Hirsch, Harald Kaspar, Gernot Löhr, Franz März, Guy Van Gool
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A fluoropolymer having a reduced amount of polar end groups. The fluoropolymer is produced by free radical polymerization of fluorinated monomers and the initiation of the polymerization is carried out in the presence of a chloride salt. Polar end groups include hydroxy groups and ionized or ionizable end groups. Examples of ionized or ionizable end groups include acid groups and salts thereof such as sulfonic acid and salts thereof, —CH2—OSO3H groups, sulfates and carbonyl containing end groups such as carboxylic and carboxylate groups. Due to the presence of chloride salt at the initiation of the free radical polymerization, CF2Cl end groups are formed instead of the polar end groups. As a result, a fluoropolymer is obtained that has improved processibility and heat resistance.
Process for preparing a fluoropolymer comprising a free radical polymerization of one or more fluorinated monomers, said free radical polymerization being initiated with an initiator in the presence of a chloride salt and whereby the ratio of said chloride salt to said initiator is selected such that the resulting fluoropolymer has at least 10% less polar end groups relative to a similar fluoropolymer produced in absence of a chloride salt, with the proviso that when said one or more fluorinated monomers consist of a mixture of tetrafluoroethylene, hexafluoropropylene and C3F7[(CF2)3O]2CF═CF2, the free radical polymerization is carried out in the absence of I(CF2)4I.
Fluoropolymer comprising CF2Cl end groups and being fee of acid groups and salts thereof or having said acid groups and their salts in an amount of not more than 0.1 milli equivalents NaOH per gram fluoropolymer, with the proviso that when said fluoropolymer is a terpolymer of tetrafluoroethylene, hexafluoropropylene and C3F7[(CF2)3O]2CF═CF2, the fluoropolymer is free of iodide containing end groups.
Method of utilizing a chloride salt in the initiation of a free radical polymerization of one or more fluorinated monomers to improve the processibility and/or heat resistance of the fluoropolymer resulting from said free radical polymerization.
Dependencies are inferred from the claim text.