EP0407566B1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Highly air permeable expanded polytetrafluoroethylene membranes and process for making them
Assignee: W.L. Gore and Associates Inc
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Filing: 1990-01-24
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Granted: 1994-11-30
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Expires: 2010-01-24
Abstract
Abstract A thin, low density porous polytetrafluoroethylene membrane having very large pores and heretofore unknown high air permeabilities is described. The membrane is produced by a particular series of longitudinal and transverse stretching steps carried out under particular conditions.
Inventors
- 👤 John E. Bacino
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 21:54
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; B; B01; B01D; B01D39/00; B01D39/14; B01D39/16; B01D39/1692; B01D67/00; B01D67/0002; B01D67/0023; B01D67/0025; B01D67/0027; B01D71/00; B01D71/06; B01D71/30; B01D71/32; B01D71/36; B29; B29C; B29C55/00; B29C55/005; B01D2239/00; B01D2239/10; B01D2325/00; B01D2325/04; B01D2325/20; B29K; B29K2027/00; B29K2027/12; B29K2027/18; B29K2105/00; B29K2105/04; B29K2995/00; B29K2995/0037; B29K2995/0065; C08J2327/00; C08J2327/02; C08J2327/12; C08J2327/18
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
61 words
A thin, low density, porous expanded polytetrafluoroethylene membrane having a very open structure defined by small nodes interconnected with fibrils, said membrane characterized by having a porosity equal to or greater than 90%, a density of 0.2 g/cm 3 or less and an air permeability of 3.0 to 10.7 litres/min/cm 2 at 12.7 mm water-pressure (Frazier numbers of 100 and 350).
Claim 2
Dependent Claim
61 words
A thin, low density, porous expanded polytetrafluoroethylene membrane having a very open structure defined by small nodes interconnected with fibrils, said membrane characterized by having a porosity equal to or greater than 90%, a density of 0.2 g/cm 3 or less and an air permeability of 3.0 to 10.7 litres/min/cm 2 at 12.7 mm water-pressure (Frazier numbers of 100 and 350).
Claim 3
Dependent Claim
46 words
The membrane of claim 1, wherein the majority of the nodes are arranged in series of generally aligned parallel rows across the membrane, and are connected node to node by fibrils and bundles of fibrils and the rows are connected to each other by long fibrils.
Claim 4
Dependent Claim
21 words
The membrane of claim 1 wherein the membrane is a film of a thickness of less than 25.4 micrometres (1 mil.).
Claim 5
Dependent Claim
21 words
A membrane of claim 2 wherein the membrane is a film of a thickness of less than 25.4 micrometres (1 mil.).
Claim 6
Dependent Claim
27 words
The membrane of claim 4 wherein the permeability to air is between 4.6 and 9.1 litres/min/cm 2 at 12.7 mm water-pressure (Frazier numbers of 150 to 300).
Claim 7
Dependent Claim
13 words
An air filtration device containing a membrane of claim 1 as the filter.
Claim 8
Dependent Claim
13 words
An air filtration device containing a membrane of claim 2 as the filter.
Claim 9
Dependent Claim
48 words
A process for the production of a thin low density, porous polytetrafluoroethylene membrane as claimed in claim 1 having a very open structure, including the step of wetting with extrusion assisting agent a polytetrafluoroethylene membrane tape formed from coagulated polytetrafluoroethylene dispersion powder and expanding the tape by wet-stretching.
Claim 10
Dependent Claim
25 words
A process as claimed in claim 8 wherein a further stretching step is carried out subsequent to the drying out of said extrusion assisting agent.
References Cited (Backward Citations)
No citation records indexed.
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