Method for forming composite polymer films

Abstract

The invention is a method for forming composite polymer films comprising: (a) forming a dispersion of a first perfluorinated polymer containing sites convertible to ion exchange groups and a dispersant 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; (b) forming a first film of the perfluorinated polymer by depositing the dispersion onto a second polymer film containing ion exchange groups or sites convertible to ion exchange groups; and (c) heating the two films for a time and at a temperature sufficient to fuse the two films to each other. Particularly preferred as a dispersant 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 dispersant is 1,2-dibromotetrafluoroethane.

Dependencies are inferred from the claim text.