Process for extraction of fluorinated copolymers with fluorocarbons
AssigneeE. I. Du Pont de Nemours and Company
InventorsTerry M. Copeland, Paul R. Resnick
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Abstract
A process for extracting a fluorinated polymer which contains carboxylic ester functional groups with a liquid compound which is preferably a perchlorofluorocarbon having a boiling point in the range of 30.degree. to 125.degree. C. is described. Polymer so extracted can be fabricated into a membrane and hydrolyzed to ion exchange form to provide a membrane for electrolytic cells. When used as the membrane for a chloralkali cell, such membrane provides improved performance, e.g., a high level of current efficiency and low power consumption are maintained for an extended period of time when compared against a membrane of like construction fabricated from polymer which has not been so extracted.
Claims14
A process comprising extracting a fluorinated polymer having --COOR functional groups, where R is lower alkyl, with a liquid compound having the formula:
- C.sub.j Cl.sub.g F.sub.f H.sub.h,
- where:
- j is an integer of at least 1,
- each of g, f and h is zero or an integer of at least 1,
- provided that g+f+h is 2j+2 in the case of alkanes, and is 2j in the case of cycloalkanes, and
- further provided that the normal boiling point is in the range of 30.degree. to 125.degree. C.,
- said extraction being carried out for a total period of time of from 15 minutes to 72 hours at a pressure in the range of 10.sup.4 to 10.sup.6 pascals, and drying the resulting extracted polymer.
Dependencies are inferred from the claim text.