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US 5,690,878 AGranted
Method for forming solution cast tetrafluoroethylene polymer films
AssigneeE. I. Du Pont de Nemours and Company
InventorsWilliam Howard Tuminello, Robert John Cavanaugh
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Abstract
Perfluorinated cycloalkane solvents for dissolving high melting polymers containing tetrafluoroethylene, are disclosed. These solvents dissolve such polymers more rapidly, and/or are more stable, than previously known solvents. Also disclosed is a process for dissolution of the polymers and their resulting solutions. The solutions are useful for making polymer films, coatings and for encapsulating objects.
Claims2
In a process for making a film of a polymer containing tetrafluoroethylene units by using a solution of the polymer in a perfluorinated cycloalkane, said process comprising:
- (1) making a thin film of the solution and removing the solvent by evaporation or extraction, or
- (2) drawing the solution and evaporating the solvent, or
- (3) extruding or co-extruding the solution, followed by removal of the solvent;
- the improvement wherein:
- the solvent is a perfluorinated cycloalkane or a perfluorinated cycloalkane containing one or more perfluoroalkyl and perfluoroalkylene groups;
- wherein a total number of carbon atoms in said perfluoroalkyl and perfluoroalkylene groups, when present, is less than a total number of ring carbon atoms in said perfluorocycloalkane;
- and wherein
- (a) the solvent has a critical temperature of 340.degree. C. or more;
- and
- (b) the polymer has a melting point of about 250.degree. C. or more.
7 more elements
Dependencies are inferred from the claim text.