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Improved porous membrane

A technology of water inlet and extrudate, applied in the field of porous membrane

Inactive Publication Date: 2011-11-09
BHA ALTAIR
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When exposed to elevated temperatures such as during steam sterilization, some previously known films do not maintain the pore size that directly affects breathability

Method used

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Examples

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Embodiment Construction

[0032] An improved membrane 20 made according to one aspect of the present invention ( figure 1 ) in the form of a sheet 22. slice 22 ( figure 2 ) combines at least two identical layers or components. The parts are in the form of extrudates 24, 26 made by a slurry extrusion process. The extrudates 24, 26 form an integral belt structure 40 ( image 3 and Figure 4 ). The unitary belt structure 40 is then biaxially stretched to form the sheet 22 of film 20 .

[0033] The resulting sheet 22 of membrane 20 is porous, and preferably microporous, with a three-dimensional matrix or lattice type structure of a plurality of nodes 62 linked by a plurality of fibrils 64 . The material from which sheet 22 of membrane 20 is made is made of expanded polytetrafluoroethylene (ePTFE) which may or may not be sintered.

[0034] The surfaces of nodes 62 and fibrils 64 define a plurality of interconnected pores that extend completely through sheet 22 of membrane 20 along tortuous paths bet...

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Abstract

The invention relates to an improved porous membrane. The membrane including a sheet of expanded polytetrafluoroethylene. The sheet is porous and has a gas permeability of at least 0.2 CFM according to ASTM D737 testing. The gas permeability of the membrane changes by less than 30% when the membrane is exposed to a temperature of 180 DEG C for a time of one hour. The sheet also has an average Mullen Hydrostatic Entry pressure of at least 135 psi according to ASTM D751 testing. The average Mullen Hydrostatic Entry pressure is substantially unchanged after exposure to a temperature of 180 DEG C for a time of one hour. The membrane has a bubble point value that changes by less than 20% when the membrane is exposed to a temperature of 180 DEG C for a time of one hour.

Description

technical field [0001] The present invention relates generally to porous membranes. In particular, the present invention relates to porous expanded polytetrafluoroethylene membranes having improved properties. Background technique [0002] Membranes made of expanded polytetrafluoroethylene (ePTFE) are known. Due to their chemical inertness, such known membranes are used in a variety of applications. Exemplary applications for the use of ePTFE membranes include waterproof and breathable clothing, fluid filtration, medical implants, and ventilation. [0003] Membranes are typically manufactured to achieve specific properties, such as breathability, resistance to water ingress, and / or stable pore size. Desired properties can often be obtained by controlling the pore size, thickness and / or basis weight of the membrane. When exposed to elevated temperatures, such as during steam sterilization, some previously known films do not maintain the pore size that directly affects bre...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B32B3/24B32B27/30
CPCA61L31/146B32B2307/724B32B27/322B01D69/02B32B5/30B32B2305/026A61L31/14B32B2038/0028A61L31/048B01D69/12B01D71/36B01D67/0027B32B2305/80B32B2309/02B32B2307/518B32B2264/0257B01D2325/20B32B37/153B32B2327/18B32B38/164B01D67/002B32B5/16B32B27/065Y10T428/249981Y10T428/249978C08L27/18B01D69/00B01D69/1212
Inventor G·托图普拉图
Owner BHA ALTAIR
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