Patent ID: 8673440
Filing Date: 2014-03-18
Classification: B01D,B29C,B29K,B29L,Y10T

Abstract:
1. A membrane comprising: a sheet of expanded polytetrafluoroethylene, wherein the sheet includes a first extrudate made from a first PTFE fine powder resin mixed with processing lubricant at a first lube rate of between 14 wt-% to 17 wt-% of the processing lubricant to the first PTFE fine powder resin, wherein the sheet further includes a second extrudate made from the first PTFE fine powder resin mixed with the processing lubricant at the first lube rate, wherein each of the first and second extrudates have a predefined thickness that is based on a die configuration of an extruder; the first extrudate forced into a portion of the second extrudate to form an integrated tape structure that is bi-axially stretched; the sheet is porous and has a gas permeability of in the range of 0.1 CFM to 0.30 CFM according to ASTM D737; and the sheet has an average Mullen Hydrostatic Burst pressure in the range of 135 psi to 175 psi according to ASTM D751.