Fluorocopolymer film and its application
View Patent ↗A fluorocopolymer film formed by molding at a molding temperature of at most 320° C. a fluorocopolymer comprising repeating units based on ethylene, repeating units based on tetrafluoroethylene, repeating units based on hexafluoropropylene and repeating units based on a fluoroalkyl vinyl ether represented by CF 2 ═CFOR f (wherein R f represents a C 1-10 fluoroalkyl group), having a molar ratio of the repeating units based on ethylene/the repeating units based on tetrafluoroethylene of from 10/90 to 60/40, a content of the repeating units based on hexafluoropropylene to the total repeating units of from 0.1 to 20 mol % and a content of the fluoroalkyl vinyl ether to the total repeating units of from 0.1 to 10 mol %, and having a volumetric flow rate of from 0.1 to 30 mm 3 /sec at 297° C.
1. A method of preparing a fluorocopolymer film, comprising: molding a fluorocopolymer at a molding temperature of at most 320° C. to obtain the fluorocopolymer film, wherein: the fluorocopolymer comprises repeating units based on ethylene, repeating units based on tetrafluoroethylene, repeating units based on hexafluoropropylene and repeating units based on a fluoroalkyl vinyl ether represented by CF 2 ═CFOR f (wherein R f represents a C 1-10 fluoroalkyl group),
a molar ratio of the repeating units based on ethylene to the repeating units based on tetrafluoroethylene in the fluorocopolymer is from 10/90 to 60/40;
a content of the repeating units based on hexafluoropropylene to the total repeating units in the fluorocopolymer is from 0.1 to 20 mol %;
a content of the repeating units based on fluoroalkyl vinyl ether to the total repeating units in the fluorocopolymer is from 0.1 to 10 mol %;
the fluorocopolymer has a volumetric flow rate of from 0.1 to 30 mm 3 /sec at 297° C. a number of fisheyes contained in the obtained fluorocopolymer film having a size of at least 0.05 mm 2 and less than 0.1 mm 2 is at most 50 per m 2 ; and a number of fisheyes contained in the obtained fluorocopolymer film having a size of at least 0.1 mm 2 is at most 15 per m 2 .
2. The method according to claim 1 , wherein R f is a perfluoroalkyl group.
3. The method according to claim 1 , wherein the fluoroalkyl vinyl ether is CF 2 ═CFO(CF 2 ) 3 F.
4. The method according to claim 1 , wherein the obtained fluorocopolymer film has an Elmendorf tear strength of at least 70N.
5. The method according to claim 1 , wherein the obtained fluorocopolymer film has a haze of at most 15%.
6. The method according to claim 1 , wherein the obtained fluorocopolymer film a tensile strength of at least 50 MPa.
7. The method according to claim 2 , wherein the obtained fluorocopolymer film has an Elmendorf tear strength of at least 70N.
8. The method according to claim 2 , wherein the obtained fluorocopolymer film has a haze of at most 15%.
9. The method according to claim 2 , wherein the obtained fluorocopolymer film has a tensile strength of at least 50 MPa.
10. The method according to claim 3 , wherein the obtained fluorocopolymer film has an Elmendorf tear strength of at least 70N.
11. The method according to claim 3 , wherein the obtained fluorocopolymer film has a haze of at most 15%.
12. The method according to claim 3 , wherein the obtained fluorocopolymer film has a tensile strength of at least 50 MPa.