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US 5,840,775 AGranted
Porous polytetraflouroethylene and preparation
AssigneeE. I. Du Pont de Nemours and Company
InventorsEdward George Howard, Jr., Arthur Zenker Moss
Life of this patent
Estimating the term…
Abstract
This invention relates to porous polyfluoroethylene (PTFE), shaped articles prepared therefrom, and to methods of preparing said articles.
Claims46
Process for preparing porous polytetrafluoroethylene (PTFE) polymer comprising:
- (a) contacting PTFE with a fluid which penetrates and swells but does not significantly dissolve the polymer or eliminate viscoelastic memory therefrom, at a temperature in the range of about 250.degree.-400.degree. C.;
- (b) cooling and separating the penetrated polymer from unabsorbed fluid, said polymer containing up to about 80% by weight of absorbed fluid;
- and
- (c) removing the absorbed fluid, to form a porous product having a single DSC melting endotherm, said endotherm being in the range of about 315.degree. to 333.degree. C. with an associated heat of fusion of at least 35 J/g.
1 more element
Process for preparing a non-draining PTFE composition comprising:
- (a) contacting PTFE, in an inert atmosphere, with a fluid which penetrates but does not significantly dissolve the PTFE or eliminate viscoelastic memory therefrom, at a temperature in the range of about 250.degree.-400.degree. C.;
- and
- (b) cooling and separating the penetrated PTFE/fluid composition from unabsorbed fluid, said composition containing up to about 80% by weight of absorbed fluid wherein said PTFE of said PTFE/fluid composition has a single DSC melting endotherm, said endotherm being in the range of about 315.degree. to 333.degree. C. with an associated heat of fusion of at least 35 J/g.
Process of preparing a composite comprising:
- (a) contacting PTFE, in an inert atmosphere, with a fluid which penetrates and swells but does not significantly dissolve the PTFE or eliminate viscoelastic memory therefrom, at a temperature in the range of about 250.degree.-400.degree. C.;
- (b) cooling and separating the penetrated, swollen PTFE from unabsorbed fluid;
- (c) removing the absorbed fluid to form a porous product;
- (d) infusing one or more polymerizable monomers and appropriate initiators into the porous product wherein the resultant PTFE porous product has a single DSC melting endotherm, said endotherm being in the range of about 315.degree. to 333.degree. C. with an associated heat of fusion of at least 35 J/g from step (c);
- and
- (e) polymerizing the one or more monomers to form the said composite.
3 more elements
Process for preparing a porous shaped solid PTFE article comprising:
- (a) forming a shaped solid article of PTFE;
- (b) contacting the shaped article, at a temperature in the range of about 250.degree. C. to 450.degree. C., with fluid which penetrates and swells the shaped article, the shaped article thereby substantially retaining its shape;
- (c) removing the fluid from the shaped article to form said porous PTFE article;
- and
- (d) stretching said article wherein the PTFE of said article has a single DSC melting endotherm, said endotherm being in the range of about 315.degree. to 333.degree. C. with an associated heat of fusion of at least 35 J/g to increase its porosity.
2 more elements
Dependencies are inferred from the claim text.