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US 7,922,946 B2Granted
PTFE membrane
AssigneeDonaldson Company, Inc.
InventorsRichard Brandimarte, Kirit Patel
Life of this patent
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Abstract
A method for improving the dimensional stability of PTFE membranes by the application of elevated temperature and elevated pressure to a PTFE membrane. The process reduces and/or eliminates the relaxation stress normally associated with PTFE membranes made using previously existing methods.
Claims15
A method of affecting the dimensional stability of a porous PTFE membrane, comprising:
- a) subjecting a PTFE membrane to an elevated temperature above the melting point of the PTFE membrane for a given exposure time;
- and
- b) subjecting the PTFE membrane at an elevated temperature to an elevated pressure for a given exposure time of less then 1 second;
- wherein the PTFE membrane after being subjected to the elevated temperature and pressure has air permeability of at least 4 liters per minute per square centimeter at 0.7 bar.
1 more element
A method of processing a PTFE membrane, the comprising the steps of:
- a) providing an oriented PTFE membrane that has been at least unilaterally oriented;
- b) simultaneously subjecting the PTFE membrane to a temperature of at least 340° C. for a period of less than 1 second and a pressure of at least 1 pound per square inch such that the PTFE membrane after being subjected to the elevated temperature and pressure has an air permeability of at least 4 liters per minute per square centimeter at 0.7 bar.
Dependencies are inferred from the claim text.