Fluoropolymer barrier material
A novel densified fluoropolymer article is described which has a water vapor permeation of about 0.015 g-mm/m 2 /day or less, and preferably has a matrix tensile strength of at least 10,000 psi in two orthogonal directions. The articles are made by compressing expanded porous PTFE at pressures, temperatures and times which result in elimination of the pores, and subsequent stretching above the crystalline melt temperature.
1 . An article comprising an expanded PTFE film having a water vapor permeability coefficient of about 0.015 g-mm/m 2 /day or less and a matrix tensile strength of at least 10,000 psi in two orthogonal directions.
2 . The article of claim 1 , wherein said film has a matrix tensile strength of at least 15,000 psi in at least one direction.
3 . The article of claim 1 , wherein said film has a matrix tensile strength of at least 25,000 psi in at least one direction.
4 . The article of claim 1 , wherein said film has a water vapor permeability coefficient of about 0.010 g-mm/m 2 day or less.
5 . The article of claim 1 , wherein said film has a water vapor permeability coefficient of about 0.003 g-mm/m 2 /day or less.
6 . The article of claim 1 , wherein said film further contains a filler.
7 . The article of claim 1 , wherein said expanded PTFE film has a thickness of 250 micrometers (μm) or less.
8 . The article of claim 1 , wherein said expanded PTFE film has a thickness of 150 micrometers (μm) or less.
9 . The article of claim 1 , wherein said expanded PTFE film has a thickness of 50 micrometers (μm) or less.
10 . The article of claim 1 , wherein said expanded PTFE film has a thickness of 10 micrometers (μm) or less.
11 . The article of claim 1 , wherein said expanded PTFE film has a thickness of 5 micrometers (μm) or less.
12 . The article of claim 1 , wherein said expanded PTFE film has a thickness of 1 micrometer (μm) or less.
13 . A laminate comprising:
(a) an expanded PTFE film having a water vapor permeability coefficient of about 0.015 g-mm/m 2 day or less and a matrix tensile strength of at least 10,000 psi in two orthogonal directions; and
at least one substrate.
14 . The article of claim 13 , wherein said film has a water vapor permeability coefficient of about 0.010 g-mm/m 2 day or less.
15 . The laminate of claim 13 , wherein said substrate comprises a fluoropolymer.
16 . The laminate of claim 13 , wherein said substrate comprises PFA.
17 . The laminate of claim 13 , wherein said substrate comprises FEP.
18 . The laminate of claim 13 , wherein said substrate comprises THV.
19 . The laminate of claim 13 , wherein said substrate comprises PTFE.
20 . The laminate of claim 13 , wherein said laminate comprises the expanded PTFE film oriented between two substrates.
21 . The laminate of claim 13 , wherein said substrate comprises PCTFE.
22 . The laminate of claim 13 , wherein said substrate comprises at least one material selected from the group consisting of polyurethane, polyethylene, polyamide, EVOH and PVDC.
23 . The laminate of claim 13 , wherein said substrate comprises at least one pressure sensitive adhesive.
24 . The laminate of claim 13 , wherein said substrate comprises at least one textile.
25 . The laminate of claim 13 , wherein said substrate comprises metal.
26 . The laminate of claim 13 , wherein said substrate comprises glass.
27 . The laminate of claim 13 , wherein said substrate comprises an inorganic sheet.
28 . A method of making a polytetrafluoroethylene (PTFE) film having a water vapor permeability coefficient of about 0.015 g-mm/m 2 /day or less, the method comprising the steps:
(a) preparing of a biaxially expanded PTFE film;
(b) densifying said expanded PTFE film;
(c) stretching the densified expanded PTFE film at a temperature exceeding the crystalline melt temperature of PTFE.
29 . The method of claim 28 , wherein the expanded PTFE film is sintered prior to step (b).
30 . The method of claim 28 , wherein said biaxially expanded PTFE film comprises two or more plies of expanded PTFE.
31 . The method of claim 28 , wherein said steps are carried out in a continuous manner.