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A composition and method of making having a perfluoroelastomer gum with a nitrogen-containing cure site and an end group represented by —CF3—CF2H, —CFH2, and/or —CH3, and having a low carbonyl-containing end group ratio, which yield cured fluoroelastomers with improved retained sealing force and art

A composition and method of making having a perfluoroelastomer gum with a nitrogen-containing cure site and an end group represented by —CF3—CF2H, —CFH2, and/or —CH3, and having a low carbonyl-containing end group ratio, which yield cured fluoroelastomers with improved retained sealing force and articles therefrom.

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1. A composition comprising: a perfluoroelastomer gum, which is thermally stable having (a) a nitrogen-containing cure site and (b) an end group represented by at least one of the following: —CF3, —CF2H, —CFH2, and —CH3;wherein an integrated absorbance ratio of carbonyl-containing end groups of the

1. A composition comprising: a perfluoroelastomer gum, which is thermally stable having (a) a nitrogen-containing cure site and (b) an end group represented by at least one of the following: —CF3, —CF2H, —CFH2, and —CH3;wherein an integrated absorbance ratio of carbonyl-containing end groups of the perfluoroelastomer gum is less than 0.08 before a heat treatment and about 16 hours after the heat treatment, the integrated absorbance ratio of carbonyl-containing end groups of the perfluoroelastomer gum is less than 0.08, wherein the heat treatment consists of heating the perfluoroelastomer gum for 30 minutes at 300° C. 2. The composition as in claim 1 wherein the perfluoroelastomer gum is a copolymer of tetrafluoroethylene and one or more perfluoro(alkyl vinyl)ether(s). 3. The composition as in claim 2 wherein the perfluoro(alkyl vinyl)ether is selected from CF3OCF2CF2CF2OCF═CF2; CF3OCF═CF2; CF3CF2OCF2OCF═CF2; CF3CF2CF2OCF2OCF═CF2; or combinations thereof. 4. The composition as in claim 1 wherein the nitrogen-containing cure site is a nitrile-containing cure site monomer. 5. The composition as in claim 4 wherein the nitrile-containing cure site monomer is selected from CF2═CFOCF2(CF2)3CF2CN; CF2═CFOCF2CF(CF3)OCF2CF2CN; or combinations thereof. 6. The composition as in claim 1 further comprising a curing agent. 7. The composition as in claim 6 wherein the curing agent is a triazine forming curing agent; a benzoxyzole forming curing agent; a benzimidazole forming curing agent; or combinations thereof. 8. The composition as in claim 6 wherein the curing agent is selected from 2,2-bis [3-amino-4-hydroxyphenyl]hexafluoropropane; 4,4′-sulfonylbis(2-aminophenol); 3,3′-diaminobenzidine; tetraphenyltin, bistetrabutylphosphonium perfluoro adipate; or combinations thereof. 9. The composition as in claim 6 wherein the curing agent is selected from a reaction product of a first component represented by the formula wherein Q+ is a non-interfering organophosphonium, organosulfonium, or organoammonium cation; each R independently represents H, halogen, a hydrocarbyl group or a halogenated hydrocarbyl group, wherein at least one carbon atom of the hydrocarbyl group may be further substituted with one or more heteroatoms selected from N, O and S; R′ represents H, a hydrocarbyl group or a halogenated hydrocarbyl group, wherein at least one carbon atom of the hydrocarbyl group may be further substituted with one or more heteroatoms selected from N, O and S; or any two of R or R′ may together form a divalent hydrocarbylene group, wherein at least one carbon atom of the hydrocarbylene group may be further substituted by one or more heteroatoms selected from N, O, and S, and a second component represented by the formula [N≡CCFR″]bZ, wherein each R″ independently represents F or CF3; b represents any positive integer; and Z represents a b-valent organic moiety free of interfering groups. 10. The composition as in claim 9 wherein the curing agent is a reaction product of CF3OCF2CF2CN and tetrabutylphosphonium 2-(p-toluoyl)-1,1,1,3,3,3-hexafluoroisopropoxide;CF3OCF2CF2CN and tetrabutylammonium 2-(p-toluoyl)-1,1,1,3,3,3-hexafluoroisopropoxide;or combinations thereof. 11. The composition as in claim 1 wherein the integrated absorbance ratio of carbonyl-containing end groups of the perfluoroelastomer gum is less than 0.05. 12. The composition as in claim 1 wherein the integrated absorbance ratio of carbonyl-containing end groups of the perfluoroelastomer gum is less than 0.01. 13. The composition as in claim 1 wherein the perfluoroelastomer gum is substantially free of at least one of the following: a) ionizable or ionized end groups other than those having carbonyl-containing end groups;b) bromine, chlorine, iodine, and nitrile end groups; andc) COF end groups. 14. The composition as in claim 1 wherein the end group comprises greater than 50% of the end groups of the perfluoroelastomer gum. 15. The composition as in claim 1 wherein the perfluoroelastomer gum further comprises a bromine end group; a chlorine end group; an iodine end group; a nitrile end group; or combinations thereof. 16. An article comprising the cured composition of claim 1. 17. The article as in claim 16, wherein the article is a gasket; seal; or sheet. 18. A method of making a fluoropolymer comprising: polymerizing in an aqueous solution at least one perfluorinated monomer and a nitrogen-containing cure site monomer in the presence of a suitable initiator, and an anion selected from a chloride anion, a cyanate anion, a thiocyanate anion or combinations thereof. 19. The method of making as in claim 18 wherein the initiator is a perfluoroalkyl sulfinate and a suitable oxidizing agent capable of oxidizing the perfluoroalkyl sulfinate to a perfluoroalkyl sulfonyl radical, which subsequently generates a perfluoroalkyl radical; oran organic peroxide. 20. The method of making as in claim 18 further comprising curing the fluoropolymer. 21. The method as in claim 19, wherein the oxidizing agent is selected from a persulfate, a bromate, a chlorate, a hypochlorite, or combinations thereof.