Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C257/00—Compounds containing carboxyl groups, the doubly-bound oxygen atom of a carboxyl group being replaced by a doubly-bound nitrogen atom, this nitrogen atom not being further bound to an oxygen atom, e.g. imino-ethers, amidines
  • C07C257/04—Compounds containing carboxyl groups, the doubly-bound oxygen atom of a carboxyl group being replaced by a doubly-bound nitrogen atom, this nitrogen atom not being further bound to an oxygen atom, e.g. imino-ethers, amidines without replacement of the other oxygen atom of the carboxyl group, e.g. imino-ethers
  • C07C257/06—Compounds containing carboxyl groups, the doubly-bound oxygen atom of a carboxyl group being replaced by a doubly-bound nitrogen atom, this nitrogen atom not being further bound to an oxygen atom, e.g. imino-ethers, amidines without replacement of the other oxygen atom of the carboxyl group, e.g. imino-ethers having carbon atoms of imino-carboxyl groups bound to hydrogen atoms, to acyclic carbon atoms, or to carbon atoms of rings other than six-membered aromatic rings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/16—Nitrogen-containing compounds
  • C08K5/29—Compounds containing one or more carbon-to-nitrogen double bonds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/04—Oxygen-containing compounds
  • C08K5/05—Alcohols; Metal alcoholates
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/49—Phosphorus-containing compounds
  • C08K5/50—Phosphorus bound to carbon only
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
  • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L27/12—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms

Definitions

• Fluoroelastomer compositions are particularly useful as seals, gaskets, and molded parts in systems that are exposed to elevated temperatures and/or corrosive materials.
• perfluorinated elastomers are used for sealing applications that require resistance to the most extreme conditions.
• 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.
• a degree of premature curing sometimes referred to in the art as incipient curing
• This premature curing is typically accompanied by a viscosity increase, and is referred to in the elastomer curing art as "scorch".
• 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.
• the present invention provides a method of making a fluoroelastomer composition, the method comprising sequentially:
• 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 1 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:
• each R" independently represents F or CF3; b represents any positive integer;
• Z represents a b-valent organic moiety free of interfering groups
• the present invention provides a curable composition comprising:
• 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:
• 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 neither of the first and second components are fluoropolymers that comprise an interpolymerized monomer unit having a nitrogen-containing cure site;
• the present invention provides catalyst composition preparable by reaction of components comprising:
• 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
• 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.
• the present invention provides a curable composition
• a curable composition comprising: (a) a catalyst composition preparable by reaction of components comprising a first component represented by Formula I:
• 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:
• 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.
• the present invention provides a method of making a fluoroelastomer composition, the method comprising combining: (a) a first component represented by Formula I:
• 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;
• 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 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
• 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.
• 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.
• Fig. 1 is a process flow diagram showing an exemplary method for making a shaped fluoroelastomer composition.
• Fig. 1 depicts method 100 for making a shaped fluoroelastomer composition.
• 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:
• Q + is a non-interfering organophosphonium, organosulfonium, or organoammonium cation.
• 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.
• Q+ examples 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.
• tetrahydrocarbylammonium such as for example,
• 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 may be H, F, Cl, Br, I, C ⁇ -C ⁇ alkyl (for example, methyl, ethyl, hexyl, isooctyl, and isopropyl), C ⁇ -C ⁇ aryl (for example, phenyl, naphthyl, biphenylyl, and phenanthryl), C ⁇ -Cjg alkaryl (for example, toluyl, isodecylphenyl, and isopropylphenyl), C ⁇ -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 (
• 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.
• R' may be H, C ⁇ -C ⁇ alkyl (for example, methyl, ethyl, hexyl, isooctyl, and isopropyl), Cg-C 14 aryl (for example, phenyl, naphthyl, biphenylyl, and phenanthryl), C ⁇ -Cjg alkaryl (for example, toluyl, isodecylphenyl, and isopropylphenyl), C ⁇ -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, methoxymeth,
• 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.
• 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.
• each R is F and R' is selected from H, phenyl, methoxyphenyl, toluyl, phenoxy, fluorophenyl, trifluoromethylphenyl, and CF 3 .
• the first component examples include tetra-alkylammonium 2-phenyl- 1,1,1 ,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 -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:
• each R" independently represents F or CF3 ; b represents any positive integer, and Z represents a b-valent organic moiety free of interfering groups.
• 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.
• b is 1, 2, or 3.
• Z is selected from hydrocarbyl, halogenated hydrocarbyl,
• Z may be perfluorinated hydrocarbyl, perfluorinated hydrocarbylene, -O-,
• Z may be C ⁇ -C ⁇ alkyl (for example, methyl, ethyl, hexyl, isooctyl, and isopropyl), Cg-C ⁇ aryl (for example, phenyl, naphthyl, biphenylyl, and phenanthryl), C ⁇ -Cig alkaryl (for example, toluyl, isodecylphenyl, and isopropylphenyl), C ⁇ -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 alkoxyalkoxylalkoxylalkylal
• the second component should typically be selected such that the equivalent weight is relatively low.
• the equivalent weight of the second component may be less than 500, 400, or even less than 250 grams per equivalent.
• 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.
• 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 + .
• alkali metal cation for example, lithium, sodium, or potassium
• alkaline earth cation for example, magnesium, calcium, or barium
• 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).
• 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).
• 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.
• 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.
• the amides may be dehydrated with other reagents such as P2O5 or PCI3.
• 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.
• adducts of the first component with the second component may be represented by the formula:
• y is any integer greater than or equal to 0 (for example, 0, 1, 2, or 3), and R, R 1 ,
• 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.
• 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.
• 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.
• 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.
• the first and second compositions may be essentially free of any fiuoropolymer comprising an interpolymerized monomer unit having a nitrogen- containing cure site.
• 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.
• 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).
• fluoropolymers include, for example, those referred to in the art as "fluoroelastomer gums" and "perfluoroelastomer gums”.
• the perfluoroalkyl, perfluoroalkoxy, and aliphatic groups have F, Br, I, and/or or Cl substituents.
• 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.
• the fluoropolymer 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.
• the non- fluorinated olefin is absent.
• the fluoropolymer contains at least 50 mole percent of its interpolymerized monomer units derived from TFE and/or CTFE, optionally including HFP.
• 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
• CX 2 CX-R ⁇ , wherein each X is, independently, hydrogen or fluorine or chlorine, R ⁇ is hydrogen, fluorine, or a C 1 -Ci 2 alkyl.
• Useful olefins include, for example, partially- fluorinated monomers (for example, vinylidene fluoride) or hydrogen-containing monomers such as olefins including ⁇ -olef ⁇ ns (for example, ethylene, propylene, butene, pentene, or hexane). Combinations of the above-mentioned materials are also useful.
• 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).
• Nitrogen-containing cure sites enable curing the fluoropolymer to form the fiuoroelastomer composition.
• 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.
• 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).
• 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.
• 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.
• 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 0 C and at a pressure in the range of 2-15 bar (0.3 - 1.5 MPa).
• Cyano groups 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.
• a perfluorosulfinate such as NC(CF2)dSO2G
• Imidate groups 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.).
• the fluoropolymer comprising at least one interpolymerized monomer unit having a nitrogen-containing cure site comprises a perfluoroelastomer
• 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.
• HFE hydrofluoroether
• the conversion of the polymer pendant cyano groups is typically performed at room temperature or at a slightly higher temperature.
• any fluorine containing inert liquid or any fluorine containing alkanol with a boiling point of at least 40 0 C, typically at least 50 0 C may be used.
• 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 0 C.
• 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.
• 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.
• 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 0 C and 230 0 C, preferably between 150 0 C and 205 0 C, 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 0 C and 300 0 C, typically at 230 0 C, for a period of from 2 hours to 50 hours or more, generally increasing with the cross-sectional thickness of the article.
• 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 0 C, 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.
• the parts are returned to ambient temperature such as by shutting off the oven heat.
• SILl silica available under the trade designation "AEROSIL R972" from Degussa AG, D ⁇ sseldorf, Germany
• FILl carbon black available under the trade designation "N-990" from Cabot, Boston, Massachusetts
• 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 0 C. 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 0 C condenser and addition funnel was charged with 1463 g of methyl-3-trifluoromethoxypropionate (6 mol) and 940 g of dimethylformamide.
• CF 3 OCF 2 CF 2 CN above starting with the corresponding acid fluoride, C 7 Fi 5 COF, CF 3 OCF 2 CF 2 CF 2 OCF(CF 3 )COF, and FCOC 4 F 8 COF.
• 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.).
• Hexafluoro-2-arylisopropanols were prepared generally according to the procedure for making hexafluoro-2-arylisopropanols was followed as described in "Perhalo Ketones.
• a 600-mL Parr reactor was loaded with 12 g OfAlCl 3 (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 0 C 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-
• Tetrabutylphosphonium 2-(p-toluyD- 1,1,1,3,3 ,3-hexafluoroisopropoxide (TBPTHD, CH 3 C n H 4 C(CF 1 W + P(C 4 H £ ) 4
• TBPTHI (3.87 g, 7.5 mmol) was placed in a glass vial.
• 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.
• 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 CF3 ⁇ CF2CF2CF2 ⁇ CF(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.
• TBPTHI 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 0 C 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.
• 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 OfCF 3 (CF 2 )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.
• 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 0 C and 7.6 g (36 mmol) of heptafluoro-3-methoxypropanenitrile was added all at once. A reaction occurred at 10 0 C by a change to a yellow colored creamy mixture. The product was warmed to room temperature while maintaining a -78 0 C condenser after which the condenser was allowed to warm to room temperature. A yellow creamy paste product, 24.5 g, was recovered.
• 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 he ⁇ tafluoro-3-methoxypropanenitrile.
• 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 0 C 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 0 C over 45 min, hold at 200 0 C for 2 hr, ramp to 250 0 C over 30 min, hold at 250 0 C for 2 hr, ramp to 300 0 C over 30 min and hold at 300 0 C for 4 hr).
• room temperature to 200 0 C over 45 min, hold at 200 0 C for 2 hr, ramp to 250 0 C over 30 min, hold at 250 0 C for 2 hr, ramp to 300 0 C over 30 min and hold at 300 0 C for 4 hr).
• 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
• 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 0 C, 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.
• MDR Monsanto Moving Die Rheometer
• Press-cured sheets 150 mm x 150 mm x 2.0 mm
• Press-cured sheets were prepared for physical property determination by pressing at a pressure of 6.9 MPa and a temperature of 177 0 C 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.
• 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.
• Mooney Scorch measurements were made at 121 0 C, 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.
• 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.

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