WO2007024869A2

WO2007024869A2 - Catalyst for making fluoroelastomer compositions and methods of using the same

Info

Publication number: WO2007024869A2
Application number: PCT/US2006/032796
Authority: WO
Inventors: Werner M. A. Grootaert; Miguel A. Guerrra
Original assignee: 3M Innovative Properties Company
Priority date: 2005-08-25
Filing date: 2006-08-22
Publication date: 2007-03-01
Also published as: BRPI0615198A2; RU2008102406A; JP2009506167A; KR20080038427A; EP1924643A2; TW200718741A; US20070049698A1; US20080033145A1; WO2007024869A3; US7294677B2; US7655591B2; CN101243128A

Abstract

A catalyst is preparable from a first component represented by R'C(CF2R)O-Q+ and a second component (NCCFR'')bZ. The catalyst may be combined with a fluoropolymer having nitrogen-containing cure-sites to form a curable composition that is useful for preparing fluoroelastomer compositions.

Description

CATALYST FOR MAKING FLUOROELASTOMER COMPOSITIONS AND METHODS OF USING THE SAME

BACKGROUND

Fluoroelastomer compositions are particularly useful as seals, gaskets, and molded parts in systems that are exposed to elevated temperatures and/or corrosive materials. For sealing applications that require resistance to the most extreme conditions, perfluorinated elastomers are used. Such parts are used in applications such as automotive, chemical processing, semiconductor, aerospace, and petroleum industries, among others.

Curable compositions used to make fluoroelastomer compositions often include a fluoropolymer comprising monomer units having a nitrogen-containing cure site to facilitate cure in the presence of a curative. One class of useful cure-site components used in fmoroelastomers includes nitrogen-containing groups such as, for example, nitriles and imidates.

Fluoroelastqmer compositions are typically prepared by combining a fluoropolymer resin or gum (sometimes referred to in the art as a fluoroelastomer gum) with one or more curatives to form a curable composition, shaping the curable mixture into a desired shape, and then curing the curable composition until the desired physical properties are achieved. During mixing of the curative(s) and fluoropolymer resin, and in subsequent handling prior to the curing step, the curable mixture may undergo a degree of premature curing (sometimes referred to in the art as incipient curing) that renders the curable composition difficult or impossible to shape. This premature curing is typically accompanied by a viscosity increase, and is referred to in the elastomer curing art as "scorch". Typically, scorch is reported with reference to "Mooney scorch" which is a measure of the incipient curing characteristics of a rubber compound using the Mooney viscometer. Mooney scorch is typically determined according to a standard test method such as, for example, ASTM D1646-04 "Standard Test Methods for Rubber— Viscosity, Stress Relaxation, and Pre- Vulcanization Characteristics (Mooney Viscometer)". In general, the lower the degree of observed scorch, the greater will be the processing window during manufacture of shaped fluoroelastomer articles.

SUMMARY In one aspect, the present invention provides a method of making a fluoroelastomer composition, the method comprising sequentially:

(a) providing a reaction product of first and second compositions, wherein the first composition comprises a first component represented by Formula I:

CF₂R

R'— C-O^" Q⁺ (I)

CF₂R

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 and R¹ 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 the second composition comprises a second component represented by Formula II:

wherein each R" independently represents F or CF3; b represents any positive integer;

Z represents a b-valent organic moiety free of interfering groups; and (b) combining the reaction product from step (a) with at least one component comprising a fluoropolymer to form a curable composition, the fluoropolymer comprising at least one interpolymerized monomer unit having a nitrogen-containing cure site; and

(c) at least partially curing the curable composition to form a fmoroelastomer. In another aspect, the present invention provides a curable composition comprising:

(a) first and second components, or a reaction product thereof, wherein the first component is represented by Formula I:

CF₂R

R¹— C-O^" Q⁺ (I)

CF₂R wherein

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 and 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 the second component is represented by Formula II:

Z represents a b-valent organic moiety free of interfering groups, and wherein neither of the first and second components are fluoropolymers that comprise an interpolymerized monomer unit having a nitrogen-containing cure site; and

(b) a fluoropolymer comprising at least one interpolymerized monomer unit having a nitrogen-containing cure site. In yet another aspect, the present invention provides catalyst composition preparable by reaction of components comprising:

(a) a first component represented by Formula I:

CF₂R

R'— C-O^" Q⁺ (I)

CF₂R

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 and 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

(b) a second component represented by Formula II:

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; and wherein the first and second compositions are essentially free of any fluoropolymer comprising an interpolymerized monomer unit having a nitrogen-containing cure site.

In yet another aspect, the present invention provides a curable composition comprising: (a) a catalyst composition preparable by reaction of components comprising a first component represented by Formula I:

CF₂R

R'— C-O^" Q⁺ (I)

CF₂R 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 and 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 (b) a second component represented by Formula II:

wherein each R" independently represents F or CF3; b represents any positive integer; Z represents a b-valent organic moiety free of interfering groups, and wherein the first and second compositions are essentially free of any fluoropolymer comprising an interpolymerized monomer unit having a nitrogen-containing cure site; and (c) a fluoropolymer comprising at least one interpolymerized monomer unit having a nitrogen-containing cure site.

In yet another aspect, the present invention provides a method of making a fluoroelastomer composition, the method comprising combining: (a) a first component represented by Formula I:

CF₂R

R-C-O^' Q (I)

CF₂R wherein

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 and 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;

(b) a second component represented by Formula II:

Z represents a b-valent organic moiety free of interfering groups, and wherein neither of the first and second components are fluoropolymers that comprise an interpolymerized monomer unit having a nitrogen-containing cure site; and (c) a fluoropolymer comprising at least one interpolymerized monomer unit having a nitrogen-containing cure site thereby forming a curable composition; and

(d) at least partially curing the curable composition to form a fluoroelastomer.

Methods of making fluoroelastomer compositions according to the present invention typically exhibit a low degree of scorch as compared to prior methods that utilize the first component alone.

Catalysts according to the present invention are useful in methods of making fluoroelastomer compositions according to the present invention.

As used herein, the term "essentially free of " means containing less than one percent by weight of;

"fluoropolymer" refers to a polymer having a fluorine content of at least 30 percent by weight, based on the total weight of the fluoropolymer;

"hydrocarbyl" refers to a univalent group formed by removing a hydrogen atom from a hydrocarbon; "hydrocarbylene" refers to a divalent group formed by removing two hydrogen atoms from a hydrocarbon, the free valencies of which are not engaged in a double bond;

"monomer" refers to a molecule that can undergo polymerization thereby contributing constitutional units to the essential structure of an oligomer or polymer, or a substance composed of such molecules; "monomer unit" refers to the largest constitutional unit contributed by a single monomer molecule to the structure of a polymer;

"nitrogen-containing cure site" refers to a nitrogen-containing group capable of participating in a cure. This can include cure by self-condensation into a triazine structure or curing through the use of curatives such as bis-aminophenols, or via free radical cure mechanisms; and

"polymer" refers to a macromolecule formed by the chemical union of at least ten identical combining units called monomers, or a substance composed of such macromolecules.

BRIEF DESCRIPTION OF THE DRAWING

Fig. 1 is a process flow diagram showing an exemplary method for making a shaped fluoroelastomer composition. DETAILED DESCRIPTION

An exemplary embodiment of the present invention is shown in Fig. 1, which depicts method 100 for making a shaped fluoroelastomer composition. In practice of method 100, first composition 10 is combined with second composition 20 to form a reaction product 30. Reaction product 30, which comprises a catalyst, is then combined with fluoropolymer 40 having nitrogen-containing cure site components to form curable composition 50. Curable composition 50 is then shaped to form shaped curable composition 60. Shaped curable composition 60 is then at least partially cured to form fluoroelastomer composition 70, which may be optionally post-cured to form post-cured fluoroelastomer composition 80.

The first composition comprises a first component represented by Formula I:

CF₂R

_N+

R— C-O^" Q (I)

CF₂R

Q⁺ is a non-interfering organophosphonium, organosulfonium, or organoammonium cation. By the term "non-interfering" it is meant that choices of Q+, which either react with the anionic portion of the first component or interfere with the curing process are excluded. Examples of Q+ include tetrahydrocarbylammonium such as for example, tributylbenzylammonium, tetrabutylammonium, and dibutyldiphenylammonium; tetrahydrocarbylphosphonium such as, for example, triphenylbenzylphosphonium, tetrabutylphosphonium, and tributylallylphosphonium; tributyl-2-methoxypropylphosphonium; trihydrocarbylsulfonium such as for example, triphenylsulfonium and tritolylsulfonium; and heteroatom substituted organophosphonium, organosulfonium, or organoammonium cations such as, for example, benzyl tris(dimethylamino)phosphonium or benzyl(diethylamino)diphenylphosphonium. 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.

For example, R may be H, F, Cl, Br, I, C\ -C γχ alkyl (for example, methyl, ethyl, hexyl, isooctyl, and isopropyl), C_β-C^ aryl (for example, phenyl, naphthyl, biphenylyl, and phenanthryl), Cγ-Cjg alkaryl (for example, toluyl, isodecylphenyl, and isopropylphenyl), Cγ-Cjg aralkyl (for example, phenylmethyl, phenethyl, and phenylpropyl), Cg-Cg cycloalkyl groups (for example, cyclohexyl, norbornyl, and [2.2.2]bicyclooctyl), C2-C12 alkoxyalkyl (for example, methoxymethyl, methoxypropyl) and alkoxyalkoxylalkyl (for example, methoxymethoxymethyl, ethoxyethoxyethyl, and methoxyethoxyethyl), C4-C6 heteroaryl (for example, pyridinyl, and pyrazinyl), and partially or perfluorinated derivatives of any of the foregoing.

In some embodiments, R' represents H or an alkyl, aryl, alkaryl, aralkyl, or cycloalkyl group, or a halogenated derivative thereof, wherein a portion of the carbon atoms may be substituted by heteroatoms selected from N, O, and S.

For example, R' may be H, C\ -C γχ alkyl (for example, methyl, ethyl, hexyl, isooctyl, and isopropyl), Cg-C 14 aryl (for example, phenyl, naphthyl, biphenylyl, and phenanthryl), Cγ-Cjg alkaryl (for example, toluyl, isodecylphenyl, and isopropylphenyl), Cγ-C^g aralkyl (for example, phenylmethyl, phenethyl, and phenylpropyl), Cg-Cg cycloalkyl groups (for example, cyclohexyl, norbornyl, and [2.2.2]bicyclooctanyl), C2- C]2 alkoxyalkyl (for example, methoxymethyl, methoxypropyl) and alkoxyalkoxylalkyl (for example, methoxymethoxymethyl, ethoxyethoxyethyl, and methoxyethoxyethyl), C4- Cg heteroaryl (for example, pyridinyl, and pyrazinyl), and partially or perfluorinated derivatives of any of the foregoing. In some embodiments, or any two of R and 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. For example, any two of the R and R' groups may together form a divalent alkyl ene (for example, ethylene, propylene, or butylene), arylene, alkarylene, aralkylene or cycloalkylene group wherein a portion of the carbon atoms may be substituted by heteroatoms selected from N, O and S.

In some embodiments, each R is F and R' is selected from H, phenyl, methoxyphenyl, toluyl, phenoxy, fluorophenyl, trifluoromethylphenyl, and CF₃.

Specific examples of the first component include tetra-alkylammonium 2-phenyl- 1,1,1 ,3 ,3 ,3 -hexafluoroisopropanoate, tetra-alkylammonium 1,1,1,3,3,3- hexafluoroisopropanoate, tetrabutylphosphonium 2-phenyl- 1 , 1 , 1 ,3 ,3 ,3- hexafluoroisopropanoate, tetrabutylphosphonium 1,1,1 ,3 ,3 ,3 -hexafluoroisopropanoate, tetrabutylphosphonium 2-methoxyphenyl- 1,1,1 ,3 ,3 ,3 -hexafluoroisopropanoate, and tetrabutylphosphonium 2-p-toluyl-l ,1 , 1 ,3,3,3-hexafluoroisopropanoate. The first component can be provided in the first composition in any form such as, for example, as a salt or as a solution of the first component dissolved in a solvent. If in solvent, the solvent should be non-interfering (that is, it does not react with the first or second components, their reaction product, or the fluoropolymer used to form the fluoroelastomer composition). Methods for making the first component fluorinated alkoxides are described, for example, iniu. S. Pat. Appln. No. 11/014,042 (Grootaert et al), filed Dec. 16, 2004. The second composition comprises a second component represented by Formula II:

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. By the term "free of interfering groups" it is meant that choices of Z that interfere with the reaction of the first component with the second component, or interfere with the curing process, are excluded. In some embodiments, b is 1, 2, or 3.

In some embodiments, Z is selected from hydrocarbyl, halogenated hydrocarbyl,

I hydrocarbylene, halogenated hydrocarbylene, -O-, -N-, -S-, and combinations thereof.

For example, Z may be perfluorinated hydrocarbyl, perfluorinated hydrocarbylene, -O-,

I -N-, -S-, and combinations thereof. For example, Z may be C\ -C γχ alkyl (for example, methyl, ethyl, hexyl, isooctyl, and isopropyl), Cg-C^ aryl (for example, phenyl, naphthyl, biphenylyl, and phenanthryl), Cγ-Cig alkaryl (for example, toluyl, isodecylphenyl, and isopropylphenyl), Cγ-Cig aralkyl (for example, phenylmethyl, phenethyl, and phenylpropyl), Cg-Cg cycloalkyl groups (for example, cyclohexyl, norbornyl, and [2.2.2]bicyclooctanyl), C2-C12 alkoxyalkyl (for example, methoxymethyl, methoxypropyl) and alkoxyalkoxylalkyl (for example, methoxymethoxymethyl, ethoxyethoxyethyl, and methoxyethoxyethyl), C4-C6 heteroaryl (for example, pyridinyl, and pyrazinyl), or a partially or perfluorinated derivative of any of the foregoing.

In order to minimize the amount of reaction product of the first and second components that must be included in the curable composition in order to achieve a desired level of cure, the second component should typically be selected such that the equivalent weight is relatively low. For example, the equivalent weight of the second component may be less than 500, 400, or even less than 250 grams per equivalent.

The reaction product of the first and second components may be prepared by other synthetic routes, although the method described above is typically the most direct method. For example, a first species represented by the formula:

CF₂R

I R'— C-O^" M⁺

I CF₂R wherein M⁺ is an alkali metal cation (for example, lithium, sodium, or potassium) or an alkaline earth cation (for example, magnesium, calcium, or barium) and R and R are as previously defined; and the second component may be allowed to react, followed by ion exchange or metathesis to replace M⁺ with Q⁺.

The second component may be provided in any form such as, for example, as a liquid or as a solution of the second component dissolved in a solvent. If in solvent, the solvent should be non-interfering (that is, it does not react with the first or second components, their reaction product, or the fluoropolymer used to form the fluoroelastomer composition). A wide variety of nitriles are available commercially or known in the chemical literature. In the case of fluorinated nitriles, which may be desirable in many instances, they may be prepared from the corresponding acid fluorides via subsequent conversion through esters and then amides. The acid fluorides may be prepared by direct fluorination or electrochemical fluorination. For secondary nitriles the acid fluorides may be prepared via hexafluoropropylene (HFPO) coupling. The acid fluorides may be converted to esters via reaction with an appropriate alcohol (such as methanol). The esters may be subsequently converted to the amides via reaction with ammonia. The amides may be dehydrated to the nitriles in an appropriate solvent (such as DMF) with pyridine and trifluoroacetic anhydride. Alternatively the amides may be dehydrated with other reagents such as P2O5 or PCI3. Without wishing to be bound by theory, it is believed that combining the first and second components, under conditions such that they mutually react, results in formation of a catalyst composition. The catalyst composition may contain a single component, but more typically contains a mixture of component species that may include at least one of 1:1, 1 :2, 1 :3, or even higher adducts of the first component with the second component, respectively. Additionally, condensation products of the second component may also be present.

For example, adducts of the first component with the second component may be represented by the formula:

wherein y is any integer greater than or equal to 0 (for example, 0, 1, 2, or 3), and R, R¹,

R", Q⁺, b, and Z are as previously defined.

The first and second components may spontaneously react, for example, as evidenced by an exotherm, or a degree of heating may be necessary in order to induce reaction. Accordingly, in some embodiments, the first and second components may be reacted to form a reaction product and then combined with a fluoropolymer having nitrogen-containing cure sites. In other embodiments such as, for example, those embodiments wherein the first and second components do not react at ambient temperatures, the first and second components and a fluoropolymer having nitrogen- containing cure sites may be combined to form a curable composition that, upon heating, forms a reaction product of the first and second components at a temperature below that wherein significant curing takes place. In such embodiments, the reaction product may then effect curing upon further heating to the curing temperature.

In either case, the reaction between the first and second components involves conversion of at least one cyano group of the second component to another chemical form as it is observed by infrared spectroscopy that the cyano group band in the infrared spectrum at least partially disappears (depending on the reaction stoichiometry) upon reaction of the first and second components.

In some embodiments, it may be desirable to control the equivalent ratio of alkoxide to nitrile that are combined. For example, the equivalent ratio of alkoxide to nitrile that are combined may be at least 1 :1, 2:1, 3:1, 5:1, or even higher, although other ratios may also be used.

In order to preserve the pot life of the resultant reaction product (that is, catalyst composition), the first and second compositions may be essentially free of any fiuoropolymer comprising nitrogen-containing cure sites, whether in pendant groups, end groups, or both. For example, the first and second compositions may be essentially free of any fiuoropolymer comprising an interpolymerized monomer unit having a nitrogen- containing cure site.

If desired, the reaction product of the first and second components may be combined with a fiuoropolymer having nitrogen-containing cure sites, thereby forming a curable composition.

Suitable fluoropolymers having nitrogen-containing cure sites typically comprise interpolymerized monomer units derived from a nitrogen-containing cure site monomer and at least one, more typically at least two, principal monomers. Examples of suitable principal monomers include perfluoroolefins (for example, tetrafluoroethylene (TFE) and hexafluoropropylene (HFP)), chlorotrifluoroethylene (CTFE), perfluorovinyl ethers (for example, perfluoroalkyl vinyl ethers and perfluoroalkoxy vinyl ethers), and optionally, hydrogen-containing monomers such as olefins (for example, ethylene, propylene), and vinylidene fluoride (VDF). Such fluoropolymers include, for example, those referred to in the art as "fluoroelastomer gums" and "perfluoroelastomer gums".

In some embodiments, the fluoropolymer comprises interpolymerized monomer units derived from tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), and/or one or more ethylenically-unsaturated monomers represented by the formulas CF₂=CF-R_f ,

2 1 1 2

CF₂=CF-O-R_f , and CH₂=CR^₂, wherein R_f is a perfluoroalkyl; R_f is a perfluoroalkyl, or a perfluoroalkoxy; and each R^ is independently selected from H, F, Cl, Br, I, or an aliphatic group. In some embodiments, the perfluoroalkyl, perfluoroalkoxy, and aliphatic groups have F, Br, I, and/or or Cl substituents. In some embodiments, the fluoropolymer comprises at least two interpolymerized monomer units derived from tetrafluoroethylene and at least one of a perfluorinated alkyl vinyl ether, perfluorinated alkoxyalkyl vinyl ether, perfluorinated alkenyl vinyl ether, or perfluorinated alkoxyalkenyl vinyl ether, respectively. If the fluoropolymer is not perfluorinated, it may contain from 5 to 90 mole percent of its interpolymerized monomer units derived from TFE, CTFE, and/or HFP, from 5 to 90 mole percent of its interpolymerized monomer units derived from VDF, ethylene, and/or propylene, up to 40 mole percent of its interpolymerized monomer units derived from a vinyl ether, and from 0.1 to 5 mole percent (for example, from 0.3 to 2 mole percent) of a nitrogen-containing cure site monomer.

In some embodiments, the fluoropolymer comprises interpolymerized monomer units corresponding to fluorinated monomers having the formula CF₂=CF-R_f, wherein R_f is fluorine or a C₁-C₈ perfluoroalkyl, and hydrogen-containing C₂-C₉ olefins, which have less than half of the hydrogen atoms substituted with fluorine, for example less than one- fourth of the hydrogen atoms substituted with fluorine. In some embodiments, the non- fluorinated olefin is absent.

In some embodiments, the fluoropolymer contains at least 50 mole percent of its interpolymerized monomer units derived from TFE and/or CTFE, optionally including HFP. In such embodiments, the balance of the interpolymerized monomer units of the fluoropolymer (10 to 50 mole percent) is typically be made up of one or more perfluoro vinyl ethers and a nitrogen-containing cure site (for example, introduced via copolymerization of a cyano group-containing vinyl ether, or by post treatment of pf -CN cure sites after the polymerization by reacting the polymer with alcohols thereby transforming the -CN cure sites into C-alkoxycarbonimidoyl (that is, -C(=NH)-OR5 wherein R5 = alkyl) cure sites). The cure site monomer typically makes up from 0.1 to 5 mole percent (more typically from 0.3 to 2 mole percent) of the fluoropolymer.

Hydrogen-containing olefins useful in the invention include those of the formula

CX₂=CX-R^, wherein each X is, independently, hydrogen or fluorine or chlorine, R^ is hydrogen, fluorine, or a C₁-Ci₂ alkyl. Useful olefins include, for example, partially- fluorinated monomers (for example, vinylidene fluoride) or hydrogen-containing monomers such as olefins including α-olefϊns (for example, ethylene, propylene, butene, pentene, or hexane). Combinations of the above-mentioned materials are also useful. In some embodiments, the fluoropolymer comprises interpolymerized monomer units derived from tetrafluoroethylene, a fluorinated comonomer, and optionally one or more perfluoro vinyl ethers. The fluorinated comonomer may be selected from perfluoroolefms, partially-fluorinated olefins, non-fluorinated olefins, vinylidene fluoride, and combinations thereof. Useful perfluorinated vinyl ethers include, for example, those described in U. S. Pat. Nos. 6,255,536 and 6,294,627 (Worm et al). Examples include CF₂=CFOCF₃, CF₂=CF-O-CF₂-O-CF₃, CF₂=CF-O-CF₂-O-CF₂CF₃, CF₂=CF-O-CF₂-O- CF₂CF₂CF₃, CF₂=CFOCF₂CF₂OCF₃, CF₂=CFOCF₂CF₂CF₂OCF₃, CF₂=CFOCF₂CF₂CF₃, CF₂=CF-O-CF₂CF(CF₃)-O-CF₃, CF₂=CFOCF₂CF(CF₃)OCF₂CF₂CF₃, CF₂=CF-O-CF₂CF₂- 0-CF₂-O-CF₂-O-CF₃, and CF₂=CFOCF₂CF(CF₃)OCF₂CF(CF₃)OCF₂CF₂CF₃.

Nitrogen-containing cure sites enable curing the fluoropolymer to form the fiuoroelastomer composition. Examples of monomers comprising nitrogen-containing groups useful in preparing fluoropolymers comprising a nitrogen-containing cure site include free-radically polymerizable nitriles, imidates, amidines, amides, imides, and amine-oxides.

Useful perfluorinated vinyl ethers that have nitrogen-containing cure sites include, for example, perfluoro(8-cyano-5-methyl-3,6-dioxa-l-octene); CF2=CFO(CF2)LCN wherein L is an integer in a range of from 2 to 12, inclusive; CF₂=CFO(CF₂)_UOCF(CF₃)CN wherein u is an integer in a range of from 2 to 6, inclusive; CF₂=CFO [CF₂CF(CF₃)O] _q(CF₂O)_yCF(CF₃)CN wherein q is an integer in a range of from O to 4, inclusive, and r is an integer in a range of from O to 6, inclusive; or CF₂=CF[OCF₂CF(CF₃)]_rO(CF₂)_tCN wherein r is 1 or 2, and t is an integer in a range of from 1 to 4, inclusive; and derivatives and combinations of the foregoing.

The amount of nitrogen-containing cure sites in a side chain position of the fluoropolymer generally is from 0.05 to 5 mole percent (more preferably from 0.1 to 2 mole percent).

Generally, the effective amount of curative, which may include more than one composition, is at least 0.1 parts curative per hundred parts of the curable composition on a weight basis, more typically at least 0.5 parts curative per hundred parts of the curable composition. On a weight basis, the effective amount of curative is typically below 10 parts curative per hundred parts of the curable composition, more typically below 5 parts curative per hundred parts of the curable composition, although higher and lower amounts of curative may also be used.

The curable composition curing may contain additional curatives such as, for example, those known in the art for curing fluoroelastomer gums, and which should typically be selected so that they do not negatively impact the curing properties of the curable composition. Examples of such additional curative include bis-aminophenols compounds (for example, see U. S. Pat. Nos. 5,767,204 (Iwa et al.) and 5,700,879 (Yamamoto et al.)), organometallic compounds (for example, see U. S. Pat. No. 4,281,092 (Breazeale)), bis-amidooximes (for example, see U. S. Pat. No. 5,621,145 (Saito et al.)), ammonia generating compounds (for example, see U. S. Pat. No. 6,281,296 (MacLachlan et al.), ammonium salts (for example, see U. S. Pat. No. 5,565,512 (Saito et al.), and amidines (for example, see U. S. Pat. No. 6,846,880 (Grootaert et al.)), peroxides, and coagents.

One or more additional fluoropolymers may be combined with the fluoropolymer having interpolymerized monomer units derived from a nitrogen-containing cure site monomer. The additional fluoropolymers may, or may not, comprise nitrogen-containing cure sites, and include the entire array described above, and including homopolymers and copolymers comprising the interpolymerized monomer units mentioned above.

The fluoropolymer comprising a nitrogen-containing cure site (for example, a cyano or imidate group), and any optional additional fluoropolymer(s) that may be incorporated in to the curable composition, may be prepared by methods including, for example, free-radical polymerization of the monomers as an aqueous emulsion polymerization or as a solution polymerization in an organic solvent. Emulsion polymerization typically involves polymerizing monomers in an aqueous medium in the presence of an inorganic free-radical initiator system, such as ammonium persulfate or potassium permanganate, and a surfactant or suspending agent.

Solvent polymerization is typically done in non-telogenic organic solvents, for example, haloperfluoro or perfluoro liquids. Any soluble radical initiator can be used, for example AIBN and bis(perfluoroacyl) peroxides. The polymerization is typically run at a temperature in the range of 25-80 ⁰C and at a pressure in the range of 2-15 bar (0.3 - 1.5 MPa). Cyano groups (that is, -CN) can typically be introduced through selected chain transfer agents like I(CF2)dCN, or by using a free-radical polymerization process can also be carried out in the presence of a perfluorosulfinate such as NC(CF2)dSO2G, where in the two preceding formulas d is an integer from 1 to 10, more typically 1 to 6, and wherein G represents a hydrogen atom or a cation with valence of 1 or 2.

Imidate groups (for example, — C(=NH)O-alkyl) may be introduced by converting cyano groups in selected polymers into imidate groups. One conversion route of cyano group-containing fluoropolymers involves the reaction of nitriles in the presence of an alcohol component and a base component at ambient temperatures. Alkyl alcohols having from 1 to 10 carbon atoms, which may be partially fluorinated, and combinations of more than one such material can be used for the alcohol component. The corresponding salt(s) of the selected alcohol or amines are preferred for the base component. Further details may be found, for example, in U. S. Pat. No. 6,803,425 (Hintzer et al.).

If the fluoropolymer comprising at least one interpolymerized monomer unit having a nitrogen-containing cure site comprises a perfluoroelastomer, then at least one swelling agent may be added to the polymer(s) prior to curing. Such swelling agent(s) may be a partially fluorinated compound such as a hydrofluoroether (HFE), (for example, available under the trade designations "3M NOVEC ENGINEERED FLUID HFE-7100" or " 3M NOVEC ENGINEERED FLUID HFE-7200" from 3M Company), or any other fluorine containing liquid such as, for example, that available under the trade designation "3M FLUORINERT LIQUID FC-75" from 3M. The conversion of the polymer pendant cyano groups is typically performed at room temperature or at a slightly higher temperature. In general, any fluorine containing inert liquid or any fluorine containing alkanol with a boiling point of at least 40 ⁰C, typically at least 50 ⁰C may be used. In the case of non-perfluorinated elastomers, a swelling agent also may be used.

Exemplary swelling agents include alcohols, inert hydrocarbon solvents, and fluorinated compounds. The necessary bases are preferably selected from alkoxides or organic amines, for example, sodium methylate or ethylate, trialkylamines, aryl-containing trialkylamines, and pyridine. The amount of base necessary to convert the nitrites is typically from 0.05 - 10 weight percent based on the weight of polymer, more typically 0.1 - 5 weight percent. If blends of fluoropolymers are desired, one useful route of incorporation is typically through blending the fluoropolymer latices in the selected ratio, followed by coagulation and drying.

Additives such as, for example, carbon black, stabilizers, plasticizers, lubricants, fillers including silica and fluoropolymer fillers (for example, PTFE and/or PFA (perfluoroalkoxy) fillers), and processing aids typically utilized in fluoropolymer compounding may be incorporated into the compositions, provided that they have adequate stability for the intended service conditions and do not substantially interfere with curing of the curable composition. The curable composition can typically be prepared by mixing one or more fluoropolymer(s), the catalyst, any selected additive or additives, any additional curatives (if desired), and any other adjuvants (if desired) in conventional rubber processing equipment. The desired amounts of compounding ingredients and other conventional adjuvants or ingredients can be added to the curable composition and intimately admixed or compounded therewith by employing any of the usual rubber mixing devices such as internal mixers, (for example, Banbury mixers), roll mills, or any other convenient mixing device. The temperature of the mixture during the mixing process typically is kept safely below the curing temperature of the composition. Thus, the temperature typically should not rise above 120 ⁰C. During mixing, it generally is desirable to distribute the components and adjuvants uniformly throughout the gum.

The curable composition is then shaped, for example, by extrusion (for example, into the shape of a film, tube, or hose) or by molding (for example, in the form of sheet, gasket, or an O-ring). The shaped article is then typically heated to at least cure the fluoropolymer composition and form a useful article. Surprisingly, it is discovered that curable compositions according to the present invention typically have an enhanced processing window as compared to corresponding compositions that use equimolar quantities of the corresponding organoonium alkoxide that has not been reacted with a nitrile. This is observed, for example in Mooney scorch times as determined by ASTM D 1646-04 "Standard Test Methods for Rubber — Viscosity, Stress Relaxation, and Pre- Vulcanization Characteristics (Mooney Viscometer)". For example, curable compositions according to the present invention may have a Mooney Scorch Time (tjg) of at least 15 minutes according to ASTM Dl 646-04. Molding or press curing of the curable mixture is typically conducted at a temperature sufficient to cure the mixture in a desired time under a suitable pressure. Generally, this is between 95 ⁰C and 230 ⁰C, preferably between 150 ⁰C and 205 ⁰C, for a period of from 1 minute to 15 hours, typically from 5 minutes to 30 minutes. A pressure of between 700 kPa and 21,000 kPa is usually imposed on the compounded mixture in a mold. The molds may be first coated with a release agent and baked.

The molded mixture or press-cured article may then, optionally, be post-cured (for example, in an oven) at a temperature and for a time sufficient to complete the curing, usually between 150 ⁰C and 300 ⁰C, typically at 230 ⁰C, for a period of from 2 hours to 50 hours or more, generally increasing with the cross-sectional thickness of the article. For thick sections, the temperature during the post-cure is usually raised gradually from the lower limit of the range to the desired maximum temperature. The maximum temperature used is preferably 300 ⁰C, and this value is held for 4 hours or more. This post-cure step generally completes the cross-linking and may also release residual volatiles from the cured compositions. Finally, the parts are returned to ambient temperature such as by shutting off the oven heat.

Objects and advantages of this invention are further illustrated by the following non-limiting examples, but the particular materials and amounts thereof recited in these examples, as well as other conditions and, details, should not be construed to unduly limit this invention.

EXAMPLES

Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, and all reagents used in the examples were obtained, or are available, from general chemical suppliers such as, for example, Sigma- Aldrich Company, Saint Louis, Missouri, or may be synthesized by conventional methods.

These abbreviations are used in the following examples: g = grams, min = minutes, mol = mole; mmol = millimole, phr = parts per hundred parts of rubber, hr = hour, ⁰C = degrees Celsius, mL = milliliter, L = liter, psi = pounds per square inch, MPa = megapascals, FTIR = Fourier transform infrared spectroscopy, and N-m = Newton-meter.

The following abbreviations are used throughout the Examples: ABBREVIATION DESCRIPTION

TFE tetrafluoroethylene

PMVE perfluoro(methyl vinyl ether)

MV5CN CF₂=CFO(CF₂)5CN

THI 2-(p-toluy I)- 1,1,1 ,3 ,3 ,3 -hexafluoroisopropanol TBPTHI tetrabutylphosphonium 2-(p-toluyl)- 1,1,1,3,3,3- hexafluoroisopropoxide

Fluoropolymer A copolymer of 65.7 mole percent TFE, 33.0 mole percent

PMVE and 1.3 mole percent MV5CN made via aqueous emulsion polymerization.

SILl silica available under the trade designation "AEROSIL R972" from Degussa AG, Dϋsseldorf, Germany

FILl carbon black available under the trade designation "N-990" from Cabot, Boston, Massachusetts

NITRILE PREPARATIONS

Preparation of Heptafluoro-3-methoxypropanenitrile, CFTO-CF₂CF₂CN

A 5 -L round bottom 3 -neck flask equipped with a -78 ⁰C condenser and mechanical stirred was charged with 1025 g of methanol and 300 g of sodium fluoride.

3-Trifluoromethoxytetrafluoropropionyl fluoride (1561 g, 6.7 mol), prepared as described in Example 1 of U. S. Pat. No. 6,482,979 (Hintzer et al.), was added to the flask at -20 ⁰C. The reaction mixture was washed with 800g water and phased split to give 1490 g of methyl-3-trifluoromethoxypropionate for a 91% yield after fractionation. A 5 -liter round bottom flask equipped with a mechanical stirrer, a -78 ⁰C condenser and addition funnel was charged with 1463 g of methyl-3-trifluoromethoxypropionate (6 mol) and 940 g of dimethylformamide. The mixture was stirred at room temperature and 125 g of ammonia (7.4 mol) was added to convert the ester to amide. Methanol was vacuum stripped and 1160 g of pyridine (14.7 mol) was added. The mixture was cooled to -14 ⁰C and 1493 g of trifluoroacetic anhydride (7.1 mol) was added. After addition was completed, 1 kg of water was added and the product began to reflux on the condenser. A total of 1165 g of heptafluoro-3-methoxypropanenitrile, CF₃OCF₂CF₂CN was obtained after distillation.

Preparation of the nitriles: C₂F₁SCN, CF₁OCF₂CF₂CF₂OCF(CFJ)CN, and NCC₄FSCN These nitriles were prepared generally as described in the procedure for

CF₃OCF₂CF₂CN above starting with the corresponding acid fluoride, C₇Fi₅COF, CF₃OCF₂CF₂CF₂OCF(CF₃)COF, and FCOC₄F₈COF. The acid fluorides were made by direct fluorination or electrochemical fluorination of the corresponding hydrocarbon analogs as described in U. S. Pat. No. 6,255,536 (Worm et al.).

ALCOHOL PREPARATION

Hexafluoro-2-arylisopropanols were prepared generally according to the procedure for making hexafluoro-2-arylisopropanols was followed as described in "Perhalo Ketones.

V.I The Reaction of Perhaloacetones with Aromatic Hydrocarbons", by B. S. Farah et al.,

Journal of Organic Chemistry (1965), vol. 30, pp. 998-1001. Preparation of 2-(ρ-toluylVU,l,3,3,3-hexafluoroisoρropanol CTiS), CH₁CgH₄C(CFs)ZOH

A 600-mL Parr reactor was loaded with 12 g OfAlCl₃ (0.09 mol, obtained from Fluka Chemika) and 326 g of toluene (3.5mol). The reactor was evacuated and 203 g of hexafluoroacetone (1.22 mol, obtained from SynQuest Laboratories, Inc.) was added over 1.5 hr with stirring at room temperature. The reaction exothermed to 45 ⁰C with a pressure rise up to 49 psi (340 kPa). The reaction was completed after one hour, accompanied by a drop in temperature and pressure. The product mixture was washed twice with 600 ml of water. The organic phase was dried with anhydrous MgSO^., filtered and distilled at 174-

176 ⁰C to give 228 g of THL

ORGANOONIUM PREPARATIONS

Preparation of Tetrabutylphosphonium 2-(p-toluyD- 1,1,1,3,3 ,3-hexafluoroisopropoxide (TBPTHD, CH₃C_nH₄C(CF₁W ⁺P(C₄H_£)₄

A 500-mL round bottom flask equipped with a stir bar was charged with 51 g of THI (0.2 mol) and 42 g of 25 weight percent sodium methoxide in methanol (0.2 mol) was added and heated to a slight methanol reflux. The flask was cooled to room temperature, and a solution of 66 g of tetrabutylphosphonium bromide (0.2 mol) in 66 g of methanol was added. The mixture was heated slightly and stirred for 0.5 hours. The solvent was vacuum stripped and the solid mass was extracted with diethyl ether and the sodium bromide was filtered out. TBPTHI (101 g) was obtained after vacuum stripping the solvent.

CATALYST PREPARATIONS

Catalyst A

TBPTHI (3.87 g, 7.5 mmol) was placed in a glass vial. To this viscous, colorless oil was added 0.945 g of NCCF2CF2CF2CF2CN (perfluoroadipoyl dinitrile, 3.75 mmol) via pipette. The vial was swirled gently at room temperature, and a slight exothermic reaction was observed, with the formation of a yellow viscous oil, which solidified upon standing. The obtained reaction product was dissolved in 5 g of methanol to produce a clear yellow solution. FTIR of Catalyst A (neat sample on KBr plate), compared to the starting TBPTHI, showed the formation of a new chemical compound and the complete loss of the -CN groups during the reaction (absence of peak at -2260 cm^"1).

Catalyst Bl TBPTHI (3.87 g, 7.5 mmol) was placed in a glass vial. To this viscous, colorless oil was added 2.45 g of CF3θCF2CF2CF2θCF(CF3)CN (7.5 mmol) via pipette. The vial was swirled gently at room temperature. The resulting mixture was dissolved in 5 g of methanol. No indication of a reaction at room temperature was observed.

Catalyst B2

As with catalyst Bl, 2.45 g of CF3θCF2CF₂CF2θCF(CF₃)CN and 3.87 g of

TBPTHI were combined in a vial in the neat form and no indication of a reaction at room temperature was observed. The vial was then heated at 60 ⁰C resulting in the rapid formation of a bright yellow-orange color which upon shaking and cooling to room temperature transformed the entire contents of the vial to a viscous, oily, yellow-orange substance. FTIR analysis of the neat reaction product (KBr disc), compared to the starting materials used, indicated the -CN function to be completely reacted.

Catalyst C TBPTHI (3.87 g, 7.5 mmol) was placed in a glass vial. To this viscous, colorless oil was added 2.96 g OfCF₃(CF₂)OCN (7.5 mmol) via pipette. The vial was swirled gently at room temperature, and a slight exothermic reaction was observed, with the formation of a deep yellow viscous oil, which solidified upon standing. The resulting mixture was dissolved in 5 g of methanol.

Catalyst D

TBPTHI (18.6 g, 36 mmol) was charged to a 250-ml round bottom flask equipped with a stir bar and a dry ice condenser. The flask was cooled to 5 ⁰C and 7.6 g (36 mmol) of heptafluoro-3-methoxypropanenitrile was added all at once. A reaction occurred at 10 ⁰C by a change to a yellow colored creamy mixture. The product was warmed to room temperature while maintaining a -78 ⁰C condenser after which the condenser was allowed to warm to room temperature. A yellow creamy paste product, 24.5 g, was recovered.

Catalyst E Catalyst E was prepared as described for catalyst D except that the molar ratio of heptafluoro-3-methoxypropanenitrile to tetrabutylphosphonium hexafluoro-2- tolylisopropoxide was 2: 1 rather than the 1 : 1 of catalyst D. The actual amounts used were 20 mmol of TBPTHI and 40 mmol of heρtafluoro-3-methoxypropanenitrile.

EXAMPLE 1

Fluoropolymer A (300 g) was compounded on a two roll mill with the addition of Catalyst A, SILl, and FILl as indicated in Table 1. The compounded mixture was press- cured at 177 ⁰C for 15 minutes. Subsequently the molded test sheets and O-rings were post-cured in air via a step-post-cure (room temperature to 200 ⁰C over 45 min, hold at 200⁰C for 2 hr, ramp to 250 ⁰C over 30 min, hold at 250 ⁰C for 2 hr, ramp to 300 ⁰C over 30 min and hold at 300 ⁰C for 4 hr).

After press-cure and post-cure, physical properties were measured with dumbbells cut from a post-cured test slab.

EXAMPLES 2 - 6 and COMPARATIVE EXAMPLE A

Example 1 was repeated with the substitution of Catalyst Bl (Example 2), B2 (Example 3), C (Example 4) and D (Example 5) and E (Example 6) for Catalyst A as indicated in Table 1 (Below). Comparative Example A used TBPTHI as the catalyst. TABLE 1

RESULTS

Rheology, physical properties, compression set and scorch are shown in Tables 2- 5.

Cure rheology tests were carried out using uncured, compounded samples using a rheometer marketed under the trade designation Monsanto Moving Die Rheometer (MDR) Model 2000 by Monsanto Company, Saint Louis, Missouri, in accordance with ASTM D 5289-93a at 177 ⁰C, no pre-heat, 30 minute elapsed time, and a 0.5 degree arc. Both the minimum torque (ML) and highest torque attained during a specified period of time when no plateau or maximum torque was obtained (MH) were measured. Also measured were the time for the torque to increase 2 units above M_L (t_s2), the time for the torque to reach a value equal to M_L + 0.5(MR - ML), (t'50), and the time for the torque to reach M_L + 0.9(M_H - ML), (t'90). Results are reported in Table 2 (below). TABLE 2

* measured after scorch test

Press-cured sheets (150 mm x 150 mm x 2.0 mm) of the curable compositions prepared in Examples 1-6 and Comparative Example A, except where indicated in Tables 3 and 4, were prepared for physical property determination by pressing at a pressure of 6.9 MPa and a temperature of 177 ⁰C for 15 min. Press-cured sheets were post-cured by exposure to heat under air using the program detailed in the examples. All specimens were returned to ambient temperature before testing.

Physical Properties

Tensile strength at break, elongation at break, and modulus at 100% elongation were determined according to ASTM D 412-92 using samples cut from the corresponding specimen using ASTM Die D.

Hardness was measured using ASTM D 2240-85 Method A with a Type A-2 Shore Durometer.

Table 3 (below) reports physical properties of the press-cured and post-cured sheets of the curable compositions of Examples 1 - 6 and Comparative Example A, except where indicated. TABLE 3

In Table 3 (above) "nm" means "not measured"

Specimens of the curable compositions of Examples 1-6 and Comparative Example A, except where indicated in Table 4, were press-cured and post-cured to form O-rings having a cross-section thickness of 0.139 inch (3.5 mm). Compression set of O- ring specimens was measured using ASTM 395-89 Method B. Results are reported in Table 4 (below) as a percentage of permanent set, and were measured at 25% deflection.

TABLE 4

EX. 1 EX. 2 EX. 3 EX. 4 EX. 5 EX. 6 COMP. EX. A

Compression set after

51.1 52. 8 nm 45. 8 31. 9 nm 39. 8 72 hr at 316

⁰C, %

In Table 4 (above) "nm" means "not measured".

Mooney Scorch measurements were made at 121⁰C, following the procedure described in ASTM D 1646-96. The procedure used employed a one minute preheat, the small rotor size and additionally measured the tjo value. Table 5 (below) reports Mooney scorch test results for curable compositions of Examples 1 — 6 and Comparative Example A.

In the case of Example 6, after the scorch test was completed, the sample was subjected to rheology tests at 177 °C, which indicated excellent cure (see Table 2). This last rheology test indicated that the catalyst was still functional and active after the 61- minute exposure to 121 °C in the compound. The scorch behavior of Example 6 (using Catalyst E) was distinctively different from Example 5 as it showed a very slight initial rise of 3 points, but then remained flat and even came down a bit during the whole scorch test. The scorch curve for Example 5 (using Catalyst D) reached t-18 at 22 minutes, but there was a steady increase in torque due to cure, and after the scorch test the specimen was cured and could not be remolded.

TABLE 5

Various modifications and alterations of this invention may be made by those skilled in the art without departing from the scope and spirit of this invention, and it should be understood that this invention is not to be unduly limited to the illustrative embodiments set forth herein.

Claims

What is claimed is:

1. A method of making a fluoroelastomer composition, the method comprising sequentially: (a) providing a reaction product of first and second compositions, wherein the first composition comprises a first component represented by Formula I:

CF₂R

R'- C-O- Q⁺ (I)

CF₂R wherein

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 and 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 the second composition comprises a second component represented by Formula II:

wherein each R" independently represents F or CF3; b represents any positive integer; Z represents a b-valent organic moiety free of interfering groups; and (b) combining the reaction product from step (a) with at least one component comprising a fluoropolymer to form a curable composition, the fluoropolymer comprising at least one interpolymerized monomer unit having a nitrogen-containing cure site; and

(c) at least partially curing the curable composition to form a fluoroelastomer.

2. A method according to claim 1, wherein the first and second compositions are essentially free of any fluoropolymer comprising an interpolymerized monomer unit having a nitrogen-containing cure site.

3. A method according to claim 1, wherein at least one of the first or second components is dissolved in solvent.

4. A method according to claim 1, wherein the second component has an equivalent weight of less than or equal to 500 grams per equivalent.

5. A method according to claim 1, wherein Z represents a b-valent group selected from hydrocarbyl, halogenated hydrocarbyl, hydrocarbylene, halogenated hydrocarbylene,

I -O-, -N-, -S-, and combinations thereof.

6. A method according to claim I₅ wherein Z represents a b-valent group selected

I from perfluorinated hydrocarbyl, perfluorinated hydrocarbylene, -O-, -N-, -S-, and combinations thereof.

7. A method according to claim 1, wherein Q⁺ is selected from the group consisting of tetrahydrocarbylammonium, tetrahydrocarbylphosphonium, and trihydrocarbylsulfonium.

8. A method according to claim I₅ wherein each R is F and R' is selected from H₅ phenyl, methoxyphenyl, toluyl, phenoxy, fluorophenyl, trifluoromethylphenyl, and CF₃.

9. A method according to claim 1 , wherein the second component is selected from the group consisting of NCCF₂CF2CF2CF₂CN, CF₃OCF₂CF₂CF₂OCF(CF₃)CN,

CF₃(CF₂)6CN, CF₃OCF₂CF₂CN, and combinations thereof.

10. A method according to claim 1 , wherein at least a portion of the cure sites comprise a cyano group.

11. A method according to claim 1 , wherein the fluoropolymer comprises interpolymerized monomer units derived from tetrafluoroethylene and a fluorinated comonomer having a nitrogen-containing cure site.

12. A method according to claim 11 , wherein the fluorinated comonomer having a nitrogen-containing cure site comprises a perfluorinated vinyl ether.

13. A method according to claim 12, wherein the perfluorinated vinyl ether comprises perfluoro(8-cyano-5-methyl-3,6-dioxa-l-octene); CF₂=CFO(CF₂)_LCN wherein L is an integer in a range of from 2 to 12, inclusive; CF₂=CFO(CF₂)_UOCF(CF₃)CN wherein u is an integer in a range of from 2 to 6, inclusive; CF₂=CFO[CF₂CF(CF₃)O]_q(CF₂O)_yCF(CF₃)CN wherein q is an integer in a range of from 0 to 4, inclusive, and r is an integer in a range of from 0 to 6, inclusive; or

CF₂=CF[OCF₂CF(CF₃)]_rO(CF₂)_tCN wherein r is 1 or 2, and t is an integer in a range of from 1 to 4, inclusive.

14. A method according to claim 13, wherein the fluoropolymers comprises interpolymerized monomer units selected from perfluoroolefins, partially-fluorinated olefins, non-fluorinated olefins, vinylidene fluoride, and combinations thereof.

15. A method according to claim 1 , wherein the fluoropolymer comprises at least two interpolymerized monomer units derived from tetrafluoroethylene and a perfluorinated vinyl ether, respectively.

16. A method according to claim 1, wherein the curable composition has a Mooney scorch time (t_lg) of at least 15 minutes according to ASTM Dl 646-04.

17. A method according to claim 1, wherein the reaction product of the first and second compositions comprises an adduct of one molecule of the first component with two molecules of the second component.

18. A method according to claim 1 , further comprising shaping the curable composition.

19. A shaped fluoroelastomer prepared according to the method of claim 18.

20. A method according to claiml, further comprising post-curing the fluoroelastomer composition.

21. A method according to claiml , wherein the at least one component further comprises filler.

22. A method according to claim 20, wherein the filler comprises at least one of fluoropolymer filler, silica, or carbon black.

23. A method according to claiml, wherein the reaction product comprises at least one component that is a condensation product of one molecule of the first component and two molecules of the second component.

24. A method according to claiml, wherein the reaction product comprises at least one component that is a condensation product of one molecule of the first component and at least three molecules of the second component.

25. A fluoroelastomer prepared according to the method of claim 1.

26. A curable composition comprising: (a) first and second components, or a reaction product thereof, wherein the first component is represented by Formula I:

CF₂R

R'— C-O^" Q⁺ (I)

CF₂R 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 and 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 the second component is represented by Formula II:

(b) a fluoropolymer comprising at least one interpolymerized monomer unit having a nitrogen-containing cure site.

27. A curable composition according to claim 26, wherein the second component is selected from the group consisting of NCCF2CF2CF2CF2CN,

CF₃OCF₂CF₂CF₂OCF(CF₃)CN, CF₃(CF₂)₆CN, CF₃OCF₂CF₂CN, and combinations thereof.

28. A curable composition according to claim 26, wherein the reaction product comprises an adduct of one molecule of the first component with two molecules of the second component.

29. A curable composition according to claim 26, wherein the reaction product comprises at least one component that is a condensation product of one molecule of the first component and at least three molecules of the second component.

30. A catalyst composition preparable by reaction of components comprising: (a) a first component represented by Formula I:

CF₂R

R¹— C-O^" Q⁺ (I)

CF₂R

wherein

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 and 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 N₅ O and S; and

(b) a second component represented by Formula II:

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; and wherein the first and second compositions are essentially free of any fluoropolymer comprising an interpolymerized monomer unit having a nitrogen-containing cure site.

31. A catalyst composition according to claim 1 , wherein the catalyst composition is preparable from one equivalent of the first component and two equivalents of the second component.

32. A curable composition comprising:

(a) a catalyst composition preparable by reaction of components comprising a first component represented by Formula I:

CF₂R

R— C-O^' Q⁺ (I)

CF₂R wherein

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 and R¹ 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 (b) a second component represented by Formula II:

Z represents a b-valent organic moiety free of interfering groups, and wherein the first and second compositions are essentially free of any fiuoropolymer comprising an interpolymerized monomer unit having a nitrogen-containing cure site; and

(c) a fiuoropolymer comprising at least one interpolymerized monomer unit having a nitrogen-containing cure site.

33. A curable composition according to claim 32, wherein the catalyst composition is preparable from one equivalent of the first component and two equivalents of the second component.

34. A method of making a fluoroelastomer composition, the method comprising combining:

(a) a first component represented by Formula I:

CF₂R

R— C-O^" Q⁺ (I)

CF₂R

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 and 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;

(b) a second component represented by Formula II:

(d) at least partially curing the curable composition to form a fiuoroelastomer.