Surface-modified fluoropolymer membrane

Patent metadata

Field	Value
Publication number	US-9649599-B2
Application number	US-201615169057-A
Country	US
Kind code	B2
Filing date	May 31, 2016
Priority date	Sep 23, 2011
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

A method for use in the manufacture of a filtration article includes providing a porous, fluoropolymer membrane, and applying a force to at least a portion of a first side surface of the membrane to modify the first side surface. The applied force may have a non-normal directional component relative to the first side surface. The surface modification may increase the density of the modified surface and/or reduce the porosity of the modified surface. Particle retention capabilities are thereby enhanced across the modified surface while maintaining permeability across the volume of the membrane.

First claim

What is claimed is:

1. A filtration article, comprising:
a porous fluoropolymer membrane, said membrane comprising a first portion and a second portion, said first portion including a frictionally-modified surface, wherein the second portion is adjacent to a surface of the first portion that is opposite of the frictionally-modified surface, and wherein said first portion has at least one of:
a first average density that is greater than a second average density of said second portion; and,
a first average porosity that is less than a second average porosity of said second portion of said membrane.

2. A filtration article as recited in claim 1 , wherein a total volume of the first portion is less than a total volume of the second portion.

3. A filtration article as recited in claim 1 , said second portion including a second side surface, wherein said frictionally-modified surface and said second side surface of said membrane are located on opposing said sides of membrane.

4. A filtration article as recited in claim 3 , wherein said frictionally-modified surface of said membrane has a specular gloss higher than a specular gloss of the second side surface.

5. A filtration article as recited in claim 1 , wherein said membrane includes a third portion, and wherein said second portion is located between said first portion and said third portion.

6. A filtration article as recited in claim 5 , wherein said third portion has a third average density that is greater than said second average density.

7. A filtration article as recited in claim 1 , said membrane having a microstructure characterized by nodes interconnected by fibrils, wherein a portion of said first surface comprises laterally displaced ones of said node and said fibrils.

8. A filtration article as recited in claim 1 , wherein said membrane provides 28 nm particle retention greater than 30 percent.

9. A filtration article as recited in claim 1 , wherein said membrane is coated with an ionomer coating.

10. A filtration article as recited in claim 1 , further comprising:
at least a first support layer disposed adjacent to one side of said membrane.

11. A filtration article as recited in claim 1 , wherein said filtration article further comprises:
a second support layer disposed on a second side of said membrane, opposite to said first side.

Assignees

• Gore & Ass

Inventors

• Mcclary Bradley Marshall
• Poddar Tarun

Classifications

• B29C59/04

  using rollers or endless belts · CPC title

• D02J1/22

  Stretching or tensioning, shrinking or relaxing, e.g. by use of overfeed and underfeed apparatus, or preventing stretch (stretch spinning D01D5/12) · CPC title

• B01D2325/42

  Ion-exchange membranes · CPC title

• B29K2027/18

  PTFE, i.e. polytetrafluoroethylene {, e.g. ePTFE, i.e. expanded polytetrafluoroethylene} · CPC title

• B01D2323/00

  Details relating to membrane preparation · CPC title