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US 4,985,296 AGranted
Polytetrafluoroethylene film
AssigneeW. L. Gore & Associates, Inc.
InventorWilliam P. Mortimer, Jr.
Life of this patent
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Abstract
A filled PTFE film is prepared by compressing an expanded, porous PTFE film that contains filler material. The films have high strength with substantially few pinholes.
Claims16
A thin film of filled polytetrafluoroethylene that:
- (a) contains 25-85 volume percent particulate filler,
- (b) has a film thickness of between 0.1 and 5 mil, and
- (c) is substantially free of visual pinholes.
Process comprising:
- (a) mixing 25-85 volume percent particulate filler of an average size of 40 micron or less with polytetrafluoroethylene in aqueous dispersion,
- (b) cocoagulating the filler and the polytetrafluoroethylene,
- (c) lubricating the filled polytetrafluoroethylene with lubricant,
- (d) (i) calendering or (ii) paste extruding and optionally calendering, to form a film,
- (e) expanding said film by stretching it so as to form an expanded porous polytetrafluoroethylene having said filler distributed therein,
- (f) densifying the stretched material by compressing it until a desired thickness is obtained.
3 more elements
Dependencies are inferred from the claim text.