Method For Producing Porous Articles From Ultra High Molecular Weight Polyethylene

Patent metadata

Field	Value
Publication number	US-2016297937-A1
Application number	US-201615145879-A
Country	US
Kind code	A1
Filing date	May 4, 2016
Priority date	Jan 30, 2013
Publication date	Oct 13, 2016
Grant date	—

Abstract

Ultra high molecular weight polyethylene (UHMWPE) polymers that have an average molecular weight of at least 500,000 g/mol and an enthalpy of at least 190 J/g is provided. The UHMWPE polymer may include at least one comonomer. The UHMWPE polymer is used to form a membrane, that when expanded, has a node and fibril structure. The UHMWPE membrane has an endotherm of about 150° C., associated with the fibrils in the membrane. The membrane has a percent porosity of at least 25%, and in exemplary embodiments, the percent porosity is at least 60%. Additionally, the UHMWPE membrane has a thickness less than 1 mm. An UHMWPE membrane may be formed by lubricating the UHMWPE polymer, subjecting the lubricated polymer to pressure at a temperature below the melting point of the UHMWPE polymer to form a tape, and expanding the tape at a temperature below the melting temperature of the UHMWPE polymer.

First claim

1 .- 28 . (canceled)

29 . A porous ultra high molecular weight polyethylene (UHMWPE) article comprising:
a porous membrane formed from a UHMWPE polymer having a molecular weight of at least about 500,000 g/mol and a melt enthalpy of about 190 J/g, said membrane having a node and fibril structure, wherein said UHMWPE membrane has a first endotherm associated with said UHMWPE polymer and a second endotherm associated with said fibril.

30 . The porous article of claim 29 , wherein said second endotherm is at a temperature higher than said first endotherm associated with said UHMWPE polymer.

31 . The porous article of claim 30 , wherein said first endotherm is from about 139° C. to about 143° C. and said second endotherm is from about 145° C. to about 155° C.

32 . The porous article of claim 29 , wherein said second endotherm is about 150° C.

33 . The porous article of claim 29 , wherein said UHMWPE polymer includes from about 0.001 mol % to about 10 mol % of a comonomer.

34 . The porous article of claim 33 , wherein said comonomer is an alpha-olefin or cyclic olefin having 3 to 20 carbon atoms.

35 . The porous article of claim 29 , wherein said UHMWPE membrane has a thickness less than about 1 mm.

36 . The process of claim 29 , wherein said UHMWPE membrane has a thickness from about 0.08 mm to about 0.5 mm.

37 . (canceled)

38 . The porous article of claim 29 , wherein said UHMWPE membrane has a porosity of at least about 60%.

39 . The porous article of claim 29 , wherein said UHMWPE membrane has a percent porosity of at least about 75%.

40 . The porous article of claim 29 , wherein said UHMWPE membrane has a percent porosity of at least about 85%.

41 . The porous article of claim 29 , wherein said UHMWPE polymer has a molecular weight from about 2,000,000 g/mol and about 4,000,000 g/mol.

42 . The porous article of claim 29 , wherein said article is selected from a sheet, membrane, fiber, tube and three dimensional self-supporting structure.

43 . The porous article of claim 29 , wherein said UHMWPE membrane has a porosity of at least about 25%.

Assignees

• Gore & Ass

Inventors

• Sbriglia Guy A

Classifications

• Y10T428/139

  Open-ended, self-supporting conduit, cylinder, or tube-type article · CPC title

• B29K2995/0077

  Yield strength; Tensile strength · CPC title

• B29C67/205

  comprising surface fusion, and bonding of particles to form voids, e.g. sintering · CPC title

• C08J5/18 Primary

  Manufacture of films or sheets · CPC title

• B29C55/12

  biaxial · CPC title