High purity transparent perfluoroelastomer parts and a process to produce the same
View Patent ↗Crosslinkable perfluoroelastomer compositions having low metal content and low compression set when crosslinked, and processes for producing the same, are provided. Compositions comprising terpolymers of TFE, PAVE, and CNVE having a metal content of less than 3000 ppb may be formed into high purity transparent perfluoroelastomer parts.
1. A method of making a cured perfluoroelastomer article comprising the steps of:
a) providing a composition comprising a crosslinkable perfluoroelastomer composition consisting essentially of a terpolymer of tetrafluoroethylene (TFE), perfluoroalkyl vinyl ether (PAVE), and perfluoro cyano vinyl ether (CNVE),
b) shaping the composition comprising the crosslinkable perfluoroelastomer composition into a shaped article,
c) heating the composition at about 250° C. or greater, and
d) crosslinking the crosslinkable perfluoroelastomer by heating the composition to form a crosslinked article
wherein the method occurs in the absence of an additional crosslinking agent, coagent or catalyst, and
wherein the crosslinked article has a metal content of less than about 3000 ppb and a compression set of less than or equal to about 50% when tested at about 200° C.
2. The method of claim 1 , comprising heating to form a crosslinked article having a compression set of less than or equal to about 40%.
3. The method of claim 1 , comprising heating to form a crosslinked article having a compression set of less than or equal to about 35%.
4. The method of claim 1 , comprising heating to form a crosslinked article having a compression set of less than or equal to about 10%.
5. The method of claim 1 , wherein the step of heating comprises heating the composition at about 250° C. or greater for about 30 minutes or longer.
6. The method of claim 1 , wherein the step of heating comprises heating the composition at about 250° C. or greater for about 60 minutes or longer.
7. The method of claim 1 , wherein the step of heating comprises heating the composition at about 300° C. or greater for about 5 minutes or longer.
8. The method of claim 1 , wherein the crosslinked article has a metal content of less than about 2000 ppb.
9. The method of claim 1 , wherein the crosslinked article has a metal content of less than about 1000 ppb.
10. The method of claim 1 , wherein the crosslinked article has a metal content of less than about 500 ppb.
11. The method of claim 1 , wherein the composition comprising the crosslinkable perfluoroelastomer has a fluorosurfactant concentration of less than 2 ppm.
12. The method of claim 1 , wherein the composition comprising the crosslinkable perfluoroelastomer has a fluorosurfactant concentration of less than 1 ppm.
13. The method of claim 1 , wherein the composition comprising the crosslinkable perfluoroelastomer has a perfluoro carboxylic acid concentration of less than 2 ppm.
14. The method of claim 1 , wherein the composition comprising the crosslinkable perfluoroelastomer has a perfluoro carboxylic acid concentration of less than 1 ppm.
15. The method of claim 1 , wherein the composition comprising the crosslinkable perfluoroelastomer has a fluoro sulfonic surfactant concentration of less than 2 ppm.
16. The method of claim 1 , wherein the composition comprising the crosslinkable perfluoroelastomer has a fluoro sulfonic acid surfactant concentration of less than 1 ppm.
17. The method of claim 1 , wherein the composition consists essentially of a crosslinkable perfluoroelastomer consisting essentially of a terpolymer of tetrafluoroethylene (TFE), perfluoroalkyl vinyl ether (PAVE), and perfluoro cyano vinyl ether (CNVE).
18. The method of claim 1 , wherein the method consists essentially of the steps of:
a) providing a composition comprising a crosslinkable perfluoroelastomer composition consisting essentially of a terpolymer of tetrafluoroethylene (TFE), perfluoroalkyl vinyl ether (PAVE), and perfluoro cyano vinyl ether (CNVE),
b) shaping the composition comprising the crosslinkable perfluoroelastomer composition into a shaped article,
c) heating the composition at about 250° C. or greater in the absence of an additional crosslinking agent, coagent or catalyst, and
d) crosslinking the crosslinkable perfluoroelastomer by heating the composition to form a crosslinked article.
19. The method of claim 18 , wherein the composition consists essentially of a crosslinkable perfluoroelastomer composition consisting essentially of a terpolymer of tetrafluoroethylene (TFE), perfluoroalkyl vinyl ether (PAVE), and perfluoro cyano vinyl ether (CNVE).