ORIENTED FLUOROPOLYMER FILM
The present invention provides oriented film comprising the composition 55 to 95 wt % tetrafluoroethylene/hexafluoropropylene/-perfluoro(alkyl vinyl ether) copolymer and 45 to 5 wt % tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer to total 100 wt % based on the combined weight of said copolymers, wherein the alkyl in each copolymer comprises 1 to 4 carbon atoms and wherein the presence of the tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer in the composition and the presence of perfluoro(alkyl vinyl ether) in both copolymers improves the thermoformability of the film as compared to oriented film of the same film thickness comprising the tetrafluoroethylene/hexafluoropropylene/perfluoro-(alkyl vinyl ether) copolymer by itself.
1 . Oriented film comprising the composition 55 to 95 wt % tetrafluoroethylene/hexafluoropropylene/perfluoro(alkyl vinyl ether) copolymer and 45 to 5 wt % tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer to total 100 wt % based on the combined weight thereof, wherein said alkyl in each said copolymer comprises 1 to 4 carbon atoms.
2 . The oriented film of claim 1 wherein the presence of said tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer and said perfluoro(alkyl vinyl ether) in both said copolymers in said composition improves the thermoformability of said film.
3 . The oriented film of claim 2 wherein the total amount of said perfluoro(alkyl vinyl ether) in both said copolymers of said composition is effective is to improve said thermoformability of said film.
4 . The oriented film of claim 2 wherein said film exhibits an improved thermoformability of at least 25%.
5 . The oriented film of claim 1 wherein the thickness of said film is no greater than 6 mils (0.015 mm).
6 . The oriented film of claim 4 wherein said thickness of said film is no greater than 3 mils (0.076 mm).
7 . The oriented film of claim 1 wherein the orientation of said film is anisotropic.
8 . The oriented film of claim 6 wherein the orientation of said film is characterized by shrinkage at 200° C. of at least 0.1%.
9 . The oriented film of claim 1 wherein said composition has a melt flow rate (MFR) of at least 10 g/10 min.
10 . The oriented film of claim 1 wherein the total amount of said perfluoro(alkyl vinyl ether) in both said copolymers of said composition is at least 2.4 wt % based on the combined weight of said copolymers.
11 . The oriented film of claim 1 wherein said perfluoro(alkyl vinyl ether) of said tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer is at least 5 wt % of said copolymer.
12 . The composition of claim 1 wherein perfluoro(alkyl vinyl ether) in said tetrafluoroethylene/hexafluoropropylene/perfluoro(alkyl vinyl ether) copolymer and said tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer is the same.
13 . The composition of claim 1 wherein said composition is the product of melt blending said 55 to 95 wt % tetrafluoroethylene/hexafluoro-propylene/perfluoro(alkyl vinyl ether) copolymer and said 45 to 5 wt % tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer to total 100 wt % based on the combined weight thereof.
14 . Process comprising thermoforming an oriented film comprising 55 to 95 wt % tetrafluoroethylene/hexafluoropropylene/perfluoro(alkyl vinyl ether) copolymer and 5 to 45 wt % tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer to total 100 wt % based on the combined weight thereof, wherein said alkyl in each said copolymer comprises 1 to 4 carbon atoms,
15 . The process of claim 14 wherein the presence of said tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer and said perfluoro(alkyl vinyl ether) in both said copolymers in said composition improves the thermoformability of said film.