Curable fluoropolymer compositions comprising a catalyst and a bishphonitrile-containing compound and articles cured

Abstract

Described herein are fluoropolymer compositions comprising an organic # imgabs0 # catalyst and a bisphthalonitrile-containing compound. As disclosed herein, by curing a highly fluorinated amorphous fluoropolymer using an organic # imgabs 1 # catalyst and a bisphthalonitrile-containing compound, a highly fluorinated elastomer can be achieved with low compression set at temperatures above 300 DEG C.

Description

Technical Field

[0001] The present disclosure relates to a curable fluoroelastomer composition comprising an organic Catalyst compounds and additives containing two phthalonitrile groups. Also described are the use of such compounds to cure amorphous fluoropolymers containing nitrile cure site groups and the cured compositions. Summary of the invention

[0002] Compression set resistance is the ability of a material to recover to its original thickness after being compressed under a load for a certain period of time at a given temperature. When highly fluorinated elastomers are tested for compression set resistance at elevated temperatures, the temperature is typically 275°C or even 300°C. However, in some applications, fluoroelastomers are used under extreme temperature conditions (e.g., at least 325°C, 330°C, or even 335°C). Therefore, there is a need to identify compositions that exhibit good compression set when subjected to extreme temperatures.

[0003] In one aspect, a composition is described comprising (i) an uncured highly fluorinated amorphous polymer comprising nitrile groups, wherein at least 80 mol % of the hydrogen atoms of the polymer backbone of the highly fluorinated amorphous polymer have been replaced by fluorine atoms, and (ii) an organic A catalyst having a cation and an anion of formula I:

[0004]

[0005] wherein each R and R' is independently H, halogen, alkyl, aryl, aralkyl or cycloalkyl, and they may also be halogenated, fluorinated or perfluorinated, optionally wherein each R group or R' group may independently contain one or more heteroatoms; wherein two or more of the R groups and R' groups may together form a ring, provided that R' cannot be halogen; and

[0006] (iii) Additives according to formula II

[0007]

[0008] Where X 1 and X 2 is independently selected from O or S, and L comprises at least one multivalent six-membered aromatic hydrocarbon group.

[0009] In another aspect, an article is described. An article comprising a cured elastomer is described, the cured elastomer being derived from a composition comprising (i) an uncured highly fluorinated amorphous polymer comprising nitrile groups, wherein at least 80 mol % of the hydrogen atoms of the polymer backbone of the highly fluorinated amorphous polymer have been replaced by fluorine atoms, and (ii) an organic A catalyst having a cation and an anion of formula I:

[0010]

[0011] wherein each R and R' is independently H, halogen, alkyl, aryl, aralkyl or cycloalkyl, and they may also be halogenated, fluorinated or perfluorinated, optionally wherein each R group or R' group may independently contain one or more heteroatoms; wherein two or more of the R groups and R' groups may together form a ring, provided that R' cannot be halogen; and

[0012] (iii) Additives according to formula II

[0013]

[0014] Where X 1 and X 2 is independently selected from O or S, and L comprises at least one multivalent six-membered aromatic hydrocarbon group.

[0015] In yet another aspect, a method comprising: Use of a catalyst of a cation and an anion of formula I and an additive according to formula II for curing uncured highly fluorinated amorphous polymers containing nitrile groups:

[0016]

[0017] wherein each R and R' is independently H, halogen, alkyl, aryl, aralkyl or cycloalkyl, and they may also be halogenated, fluorinated or perfluorinated, optionally wherein each R group or R' group may independently contain one or more heteroatoms; wherein two or more of the R groups and R' groups may together form a ring, provided that R' cannot be halogen;

[0018]

[0019] Where X 1 and X 2 is independently selected from O or S, and L comprises at least one multivalent six-membered aromatic hydrocarbon group, wherein at least 80 mol % of the hydrogen atoms of the polymer backbone of the highly fluorinated amorphous polymer have been replaced by fluorine atoms.

[0020] The above summary of the invention is not intended to describe every embodiment. The details of one or more embodiments of the present invention are also listed in the following detailed description. Other features, objectives and advantages will be apparent from this specification and claims. DETAILED DESCRIPTION

[0021] As used herein, the term

[0022] "A", "an" and "the" are used interchangeably and refer to one or more; and

[0023] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B);

[0024] "Backbone" means the main continuous chain of a polymer;

[0025] “Cross-linking” refers to the use of chemical bonds or chemical groups to connect two preformed polymer chains;

[0026] “Cure sites” refer to functional groups that can participate in cross-linking;

[0027] "Interpolymerization" means polymerizing monomers together to form a polymer backbone;

[0028] A "monomer" is a molecule that can be polymerized and then form the basic structural part of a polymer;

[0029] "Perfluorinated" means a group or compound derived from hydrocarbons in which all hydrogen atoms are replaced by fluorine atoms. However, perfluorinated compounds may also contain other atoms besides fluorine and carbon atoms, such as oxygen, chlorine, bromine and iodine atoms; and

[0030] "Polymer" refers to a macrostructure having a number average molecular weight (Mn) of at least 30,000 Daltons, at least 50,000 Daltons, at least 100,000 Daltons, at least 300,000 Daltons, at least 500,000 Daltons, at least 750,000 Daltons, at least 1,000,000 Daltons, or even at least 1,500,000 Daltons, and the molecular weight is not so high as to cause premature gelation of the polymer.

[0031] As used herein, and as known in the art, such structures The horizontal line intersecting the benzene ring shown in represents a bond connected to any one of the vertices of the ring.

[0032] Also herein, ranges recited by endpoints include all numbers subsumed within that range (eg, 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0033] Moreover, as used herein, the expression "at least one" includes all numbers from one to greater than one (eg, at least 2, at least 4, at least 6, at least 8, at least 10, at least 25, at least 50, at least 100, etc.).

[0034] As used herein, "comprising at least one of A, B, and C" means comprising only element A, only element B, only element C, A and B, A and C, B and C, and a combination of all three.

[0035] The present invention relates to compounds containing diphthalonitrile and organic Use of a catalyst to cure highly fluorinated amorphous fluoropolymers containing nitrile cure sites. It has been found that the resulting cured highly fluorinated elastomers have good high temperature properties.

[0036] Fluoropolymers

[0037] As used herein, a "highly fluorinated" polymer is one in which at least 80 mol % (e.g., at least 90 mol % or even at least 95 mol %) of the hydrogen atoms of the polymer backbone have been replaced by fluorine atoms. In some embodiments, 0 to 20 mol % (e.g., 5 to 15 mol %) of the hydrogen atoms of the polymer backbone may be replaced by chlorine atoms. In some embodiments, these highly fluorinated polymers may include one or more hydrogen-containing end groups or side groups that are not considered part of the polymer backbone.

[0038] In some embodiments, the highly fluorinated fluoropolymer is a copolymer of tetrafluoroethylene (TFE) and one or more perfluorinated comonomers. In some embodiments, at least one perfluorinated comonomer is a perfluoroalkyl vinyl ether (PAVE), including perfluoroalkyl alkoxy vinyl ether. Suitable PAVE includes perfluoromethyl vinyl ether (PMVE), perfluoroethyl vinyl ether (PEVE) and perfluoropropyl vinyl ether (PPVE-1 and PPVE-2). In some embodiments, at least one perfluorinated comonomer is a perfluoroalkyl allyl ether (PAAE), including perfluoroalkyl alkoxy allyl ether. Suitable PAAE includes perfluoromethyl allyl ether (MA-1), perfluoroethyl allyl ether (MA-2) and perfluoropropyl allyl ether (MA-3).

[0039] In some embodiments, at least one perfluorinated comonomer is a perfluorinated α-olefin other than TFE, such as hexafluoropropylene (HFP). Additional optional comonomers include partially fluorinated α-olefins (e.g., CH 2 =CF 2, VDF); F- and Cl-containing olefins, such as chlorotrifluoroethylene; and non-fluorinated alpha olefins, such as ethylene or propylene.

[0040] In some embodiments, the fluoropolymer is perfluorinated, i.e., at least 99 mol % or even 100 mol % of the hydrogen atoms of the polymer backbone have been replaced by fluorine atoms or chlorine atoms (preferably fluorine atoms). If chlorine atoms are present, they account for no more than 20 mol %, e.g., no more than 10 mol %, based on the total moles of fluorine atoms and chlorine atoms on the polymer backbone. In some embodiments, the perfluorinated polymer comprises no more than 5 mol % (e.g., no more than 1 mol % or even no more than 0.01 mol %) of chlorine atoms, based on the total moles of fluorine atoms and chlorine atoms on the polymer backbone.

[0041] Typically, highly fluorinated fluoropolymers contain a sufficient number of nitrile groups (C≡N) to achieve the desired degree of curing (i.e., crosslinking). In some embodiments, the fluoropolymer contains at least 0.1 mol % of nitrile groups, such as at least 0.5 mol % or even at least 1 mol % of nitrile groups. In some embodiments, the fluoropolymer contains no more than 5 mol %, such as no more than 2 mol % or even no more than 1.5 mol % of nitrile groups.

[0042] In some embodiments, the nitrile groups are introduced by copolymerizing a cure site monomer containing a nitrile group with other comonomers (e.g., TFE, PAVE, and PAAE comonomers). Examples of nitrile-containing cure site monomers correspond to the following formula: CF 2 =CF-CF 2 -O-Rf-CN; CF 2 =CFO(CF 2 ) r CN; CF 2 =CF[OCF 2 CF(CF 3 )] k O(CF 2 ) u CN; and CF 2 =CFO[CF 2 CF(CF 3 )O] p (CF 2 ) v OCF(CF 3 )CN, wherein r represents an integer from 2 to 12; p represents an integer from 0 to 4; k represents 1 or 2; v represents an integer from 0 to 6; u represents an integer from 1 to 6, and Rf is a perfluoroalkylene group or a divalent perfluoroether group. Specific examples of nitrile-containing fluorinated monomers include, but are not limited to, CF 2 =CFOCF 2 CF(CF3 )OCF 2 CF 2 CN、CF 2 =CFOCF 2 (CF 2 ) 3 CF 2 CN and CF 2 =CFOCF 2 (CF 2 ) 3 CF(CF 3 )CN.

[0043] If the amorphous fluoropolymer is perfluorinated, then typically at least 50 mol% (mol%) of its interpolymerized units are derived from TFE, optionally including HFP. The remainder of the interpolymerized units of the amorphous fluoropolymer (e.g., 10 mol% to 50 mol%) is composed of one or more perfluorinated vinyl ethers or perfluorinated allyl ethers as described above in its embodiments and a curing site monomer as described above in its embodiments. In some embodiments, the molar ratio of the unit derived from the TFE comonomer unit to the comonomer unit derived from the above-mentioned perfluorinated vinyl ether or perfluorinated allyl ether can be, for example, 1:1 to 4:1, wherein the unsaturated ether can be used as a single compound or as a combination of two or more unsaturated ethers. A typical composition comprises 44 wt% to 62 wt% of TFE and 38 wt% to 56 wt% of PMVE and 0.1 wt% to 10 wt% of curing site monomers and 0 wt% to 10 wt% of other comonomers or modifiers, wherein the amount of each component is selected so that the total amount is 100 wt%.

[0044] If the amorphous fluoropolymer is not perfluorinated, it generally contains about 5 mol% to about 90 mol% of its interpolymerized units derived from TFE, CTFE and / or HFP; about 5 mol% to about 90 mol% of its interpolymerized units derived from VDF, ethylene and / or propylene; up to about 40 mol% of its interpolymerized units derived from perfluorinated vinyl ethers or perfluorinated allyl ethers as described above in any embodiment thereof; and about 0.1 mol% to about 5 mol%, in some embodiments, about 0.3 mol% to about 2 mol% of cure site monomers. Some typical compositions contain about 22 wt% to 30 wt% TFE, 30 wt% to 38 wt% VDF, 34 wt% to 42 wt% HFP, and 0.1 wt% to 10 wt% of cure site monomers and 0 wt% to 10 wt% of other comonomers or modifiers, wherein the amount of each ingredient is selected so that the total amount is 100 wt%.

[0045] Examples of amorphous perfluoropolymers useful in the present disclosure include TFE / perfluoromethyl vinyl ether (PMVE) copolymers, TFE / perfluoromethyl allyl ether (PMAE) copolymers, TFE / CF 2 =CFOC 3 F 7 Copolymer, TFE / CF 2 =CFCF 2 OC 3 F 7 Copolymer, TFE / CF 2 =CFOCF 3 / CF 2 =CFOC 3 F 7 Copolymer, TFE / CF 2 =CFCF 2 OCF 3 / CF 2 =CFCF 2 OC 3 F 7 In some embodiments, the amorphous fluoropolymers useful in the present disclosure include TFE / propylene copolymers, TFE / propylene / VDF copolymers, VDF / HFP copolymers, TFE / VDF / HFP copolymers, TFE / ethyl vinyl ether (EVE) copolymers, TFE / butyl vinyl ether (BVE) copolymers, TFE / EVE / BVE copolymers, VDF / CF 2 =CFOC 3 F 7 Copolymers, ethylene / HFP copolymers, CTFE / VDF copolymers, TFE / VDF copolymers, TFE / VDF / PMVE / ethylene copolymers and TFE / VDF / CF 2 =CFO(CF 2 ) 3 OCF 3 Copolymers. Each of the foregoing copolymers will contain monomer units having cure sites.

[0046] organic catalyst

[0047] The catalyst of the present disclosure comprises an organic The cation and the anion represented by formula I:

[0048]

[0049] In Formula I, each R and R' is independently hydrogen, halogen (i.e., -F, -Cl, -Br or -I), alkyl, aryl, arylalkylene or alkylarylene, wherein alkyl, aryl, arylalkylene or alkylarylene can each be unsubstituted or each can be substituted by one or more halogens, provided that R' is not halogen. In some embodiments, any two of the R and R' groups can be connected together to form a ring. For example, any two of the R and R' groups can be connected together to form a divalent alkylene (e.g., ethylene, propylene or butylene), arylene, alkylarylene or arylalkylene group, wherein a portion of the carbon atoms can be substituted by heteroatoms selected from N, O and S.

[0050] In some embodiments, each R is independently hydrogen, halogen (i.e., -F, -Cl, -Br, or -I), alkyl having up to 12 carbon atoms (e.g., methyl, ethyl, hexyl, isooctyl, isopropyl, cyclohexyl, norbornyl, and [2.2.2]bicyclooctyl), C 6 -C 14 Aryl (e.g., phenyl, naphthyl, biphenyl, pyridyl, pyrazinyl, and phenanthryl), C 7 -C 18 Alkyl arylene (e.g., toluoyl, isodecylphenyl and isopropylphenyl), C 7 -C 18 Arylalkylene (e.g., benzyl, phenethyl, and phenylpropyl), C 2 -C 12 Alkoxyalkyl (eg, methoxymethyl, methoxypropyl) and alkoxyalkoxyalkyl (eg, methoxymethoxymethyl, ethoxyethoxyethyl, and methoxyethoxyethyl), and partially or fully fluorinated derivatives of any of the foregoing. In some embodiments, each R is -F.

[0051] In some embodiments, R' is independently alkyl having up to 12 carbon atoms (eg, methyl, ethyl, hexyl, isooctyl, isopropyl, cyclohexyl, norbornyl, and [2.2.2]bicyclooctyl), C 6 -C 14 Aryl (e.g., phenyl, naphthyl, biphenyl, pyridyl, pyrazinyl, and phenanthryl), C 7 -C 18 Alkyl arylene (e.g., toluoyl, isodecylphenyl and isopropylphenyl), C 7 -C 18 Arylalkylene (e.g., benzyl, phenethyl, and phenylpropyl), C 2 -C 12In some embodiments, R' is a perfluoroalkyl radical having a maximum of 12 carbon atoms, 11 carbon atoms, 10 carbon atoms, 9 carbon atoms, 8 carbon atoms, 7 carbon atoms, 6 carbon atoms, 5 carbon atoms, 4 carbon atoms, 3 carbon atoms, or 2 carbon atoms. In some embodiments, R' is not a perfluoroalkyl radical having a maximum of 12 carbon atoms, 11 carbon atoms, 10 carbon atoms, 9 carbon atoms, 8 carbon atoms, 7 carbon atoms, 6 carbon atoms, 5 carbon atoms, 4 carbon atoms, 3 carbon atoms, or 2 carbon atoms. In some embodiments, R' is hydrogen, phenyl, methoxyphenyl, toluoyl, fluorophenyl, trifluoromethylphenyl, or trifluoromethyl. In some embodiments, R' is not trifluoromethyl. In some embodiments, R' is toluoyl.

[0052] Organic compounds that can be used in catalysts Cations include sulfonium cations, phosphonium cations and ammonium cations. The cation may be a trialkylsulfonium, tetraalkylphosphonium or tetraalkylammonium cation. Useful hydrocarbon groups include alkyl, aryl, arylalkylene and alkylarylene groups, each of which can be unsubstituted or substituted with at least one of a halogen, an alkoxy, a (di)alkylamino, a hydroxyl group. The cation may be a trialkylsulfonium, tetraalkylphosphonium, or tetraalkylammonium cation. In the trialkylsulfonium, tetraalkylphosphonium, or tetraalkylammonium cation, each alkyl group independently has up to 12 carbon atoms. In some embodiments, each alkyl group independently has up to 11 carbon atoms, 10 carbon atoms, 9 carbon atoms, 8 carbon atoms, 7 carbon atoms, 6 carbon atoms, 5 carbon atoms, 4 carbon atoms, 3 carbon atoms, or 2 carbon atoms. Available organic Examples of cations include tributylbenzylammonium, tetrabutylammonium, dibutyldiphenylammonium, triphenylbenzylphosphonium, tetrabutylphosphonium and tributylallylphosphonium, tributyl-2-methoxypropylphosphonium, triphenylsulfonium, tritolylsulfonium, benzyltris(dimethylamino)phosphonium and benzyl(diethylamino)diphenylphosphonium. In some embodiments, the cation is tetramethylammonium or tetrabutylphosphonium. In some embodiments, the cation is tetrabutylphosphonium.

[0053] In some embodiments, the catalyst that can be used in the composition of the present disclosure is not tetramethylammonium perfluoro-tert-butyl alcohol and tetrabutylphosphonium perfluoro-tert-butyl alcohol. In some embodiments, the catalyst that can be used in the composition of the present disclosure includes 2-p-toluoyl-1,1,1,3,3,3-tetrabutylphosphonium hexafluoroisopropionate. Organic The catalyst composition can be prepared using methods known in the art, for example, as disclosed in US Pat. No. 8,906,821 (Grootaert et al.).

[0054] Exemplary catalysts include tetra-alkylammonium 2-phenyl-1,1,1,3,3,3-hexafluoroisopropanoate, tetra-alkylammonium 1,1,1,3,3,3-hexafluoroisopropanoate, tetra-butylphosphonium 2-phenyl-1,1,1,3,3,3-hexafluoroisopropanoate, tetra-butylphosphonium 1,1,1,3,3,3-hexafluoroisopropanoate, tetra-butylphosphonium 2-methoxyphenyl-1,1,1,3,3,3-hexafluoroisopropanoate, or tetra-butylphosphonium 2-p-toluoyl-1,1,1,3,3,3-hexafluoroisopropanoate.

[0055] Compounds containing diphthalonitrile

[0056] The bisphthalonitrile-containing compounds of the present disclosure are according to formula (II):

[0057]

[0058] Where X 1 and X 2 are independently selected from O or S, and L comprises at least one polyvalent aromatic hydrocarbon group. 1 -LX 2 The group is bonded to the ortho or meta position of a nitrile group in the nitrile (-C≡N) group. L is a polyvalent linking group comprising at least one polyvalent aromatic hydrocarbon group. L may comprise one or more hexavalent aromatic hydrocarbon groups. In one embodiment, L comprises a polyvalent fused polycyclic portion. The polyvalent linking group L may be divalent, trivalent or tetravalent.

[0059] In one embodiment, L is

[0060]

[0061] The two horizontal lines represent (i) a vertex of the 6-membered aromatic ring and X 1 The bonds between (ii) different vertices of the aromatic ring and X 2 The two bonds can be ortho, meta or para to each other. 1 Between the aromatic ring and X 2 In addition to the two bonds between the aromatic hydrocarbon groups, there may also be other non-functional groups bonded to the aromatic hydrocarbon groups which do not cause steric hindrance, such as at least one methyl, methoxy, ethyl and / or ethoxy group.

[0062] In one embodiment, L is phenylene or substituted phenylene. For example, in one embodiment, L is

[0063]

[0064] The two horizontal lines in each structure represent (i) the connection between a vertex of the aromatic ring and X 1 and (ii) different vertices of the aromatic ring and X 2 The two bonds may be ortho, meta or para to each other. In addition to the two bonds, other non-functional groups bonded to the aromatic ring may also be present, such as those indicated by R above. 1 and R 2 As shown, these non-functional groups do not cause steric hindrance, and such non-functional groups include short chain (e.g., C1-C4) alkyl groups and alkoxy groups. 1 Group and R 2 Groups include: methyl, methoxy, ethyl and ethoxy groups.

[0065] In another embodiment, L comprises more than one aromatic group, such as naphthalene, anthracene, phenanthrene, or a divalent group having the structure:

[0066]

[0067] Where R 4 Select from free bonds, -S-, -O-, -C(CF 3 ) 2 -、-C(CH 3 ) 2 -、-CH 2 -、-SO 2 -, -C(=O)- and -C(CH 3 ) 2 -C 6 H 4 -C(CH 3 ) 2 In the above structure of L, L and X of the compound containing diphthalonitrile are connected 1 and X 2 The bond can be located relative to R 4 For example, with X 1 and X 2 The bonds can be independently R 4 More preferably, with X 1 and X 2 The bond relative to R 4 The groups are all ortho, all meta or all para. 1 Between phenylene and R 4In addition to the two bonds between the phenylene groups, there may be other non-functional groups bonded to the phenylene groups that do not cause steric hindrance, such as at least one methyl, methoxy, ethyl and / or ethoxy group. 1 and R 2 Groups include: methyl, methoxy, ethyl and ethoxy groups.

[0068] In one embodiment, L comprises a fused polyaryl ring such as naphthalene, anthracene, phenanthrene or

[0069] Exemplary compounds of formula (II) include:

[0070]

[0071] Curable composition

[0072] According to the organic The catalyst and the bisphthalonitrile-containing compound of formula (II) can be used to cure highly fluorinated amorphous fluoropolymers containing nitrile groups.

[0073] In one embodiment, at least 0.05, 0.1, or even 1 part by weight and at most 2, 4, 6, or even 10 parts by weight of organic acid are used per 100 grams of amorphous highly fluorinated polymer. Catalyst. In one embodiment, the compound containing bisphthalonitrile according to formula (II) is used in an amount of at least 0.05 parts by weight, 0.1 parts by weight or even 1 part by weight, and at most 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 8 parts by weight or even 10 parts by weight per 100 grams of amorphous highly fluorinated polymer.

[0074] In some embodiments, an amorphous fluoropolymer comprising highly fluorinated nitrile-containing groups, an organic The curable composition of the catalyst and the bisphthalonitrile-containing compound of formula (II) may also contain various types of additives commonly used in preparing elastomeric compositions, such as acid acceptors, processing aids, pigments, fillers, pore formers and those additives known in the art.

[0075] Such fillers include organic or inorganic fillers such as clay, silica (SiO 2 ), alumina, red iron, talc, diatomaceous earth, barium sulfate, wollastonite (CaSiO 3 ), calcium carbonate (CaCO 3), calcium fluoride, titanium oxide, iron oxide and carbon black fillers, polytetrafluoroethylene powder, PFA (TFE / perfluorovinyl ether copolymer) powder, conductive fillers, heat dissipation fillers, etc. can be added to the composition as optional components. Those skilled in the art can select the desired amount of specific fillers to achieve the desired physical properties of the vulcanized compound. The filler component can produce a compound that can maintain the preferred elasticity and physical tension (as indicated by the elongation and tensile strength values) while maintaining the desired properties such as shrinkage at lower temperatures (TR-10).

[0076] In one embodiment, the composition comprises less than 50%, 40%, 30%, 20%, 15% or even 10% by weight of inorganic filler.

[0077] Conventional adjuvants may also be incorporated into the compositions of the present disclosure to enhance the properties of the resulting compositions. For example, acid acceptors may be used to promote the curing stability and thermal stability of the compound. Suitable acid acceptors may include magnesium oxide, lead oxide, calcium oxide, calcium hydroxide, lead hydrogen phosphite, zinc oxide, barium carbonate, strontium hydroxide, calcium carbonate, hydrotalcite, alkaline stearate, magnesium oxalate or a combination thereof. Acid acceptors are preferably used in an amount in the range of about 1 part to about 20 parts per 100 parts by weight of polymer.

[0078] Usually, organic Catalysts, compounds containing diphthalonitrile and optional additives are blended with highly fluorinated amorphous fluoropolymers and formed into articles such as sheets and O-rings using commonly known equipment and methods. For example, the compounded composition can be press-cured at a temperature of at least 175°C (e.g., at least 185°C). In some embodiments, the press-curing temperature does not exceed 225°C or even does not exceed 200°C. The degree of cure can be determined according to the curing rheology test described in the examples. The press-curing time is selected to achieve the desired level of cure, which can be determined by the temperature of the press-curing agent in the M H Typically, sufficient curing is indicated by the H The curing time is preferably not more than 0.5, such as not more than 0.2, or even not more than 0.1, as measured according to the Curing Rheology Test described below. For most applications, t'90 (as measured according to the Curing Rheology Test) should be less than 20 minutes, such as not more than 10 minutes. In order to minimize the risk of scorch, t'90 should be at least 2 minutes. In some embodiments, longer curing times (e.g., t'90 values ​​of at least 4 minutes) may be beneficial.

[0079] Ideally, the molded mixture or pressurized cured article (e.g., in an oven) is post-cured at a temperature and time sufficient to complete the curing. Post-curing is usually between about 150°C and about 300°C, typically at about 230°C, for about 2 hours to 50 hours or longer, usually increasing with the cross-sectional thickness of the article. For thick sections, the temperature during post-curing is usually gradually increased from the lower limit of the range to the desired maximum temperature. The maximum temperature used is usually about 300°C, and the temperature is maintained for about 4 hours or more. The post-curing step usually completes cross-linking, and residual volatiles can also be released from the cured composition. In one embodiment, post-curing involves exposing the molded parts to non-isothermal thermal cycles. For example, the temperature is increased from room temperature to 150°C in 2 hours and maintained at 150°C for 7 hours, then raised to 300°C in 2 hours and maintained at 300°C for 2 hours. Finally, the part is raised to 320°C over 15 minutes and held for 15 minutes, then returned to ambient temperature (e.g., by turning off the oven heat). Another example of a suitable post-cure cycle involves exposing the molded part to heat under nitrogen using six stages of conditions. First, the temperature is increased from 25°C to 200°C over a period of 6 hours, then the part is held at 200°C for 16 hours, after which the temperature is increased from 200°C to 250°C over a period of 2 hours. The part is then held at 250°C for 8 hours, after which the temperature is increased from 250°C to 300°C over a period of 2 hours. The part is then held at 300°C for 16 hours. Finally, the part is returned to ambient temperature by, for example, turning off the oven heat.

[0080] In some applications, such as O-rings and seals, compression set is a key property. In some embodiments, the cured compositions of the present disclosure have improved compression set, especially at higher temperatures, such as at 300°C, 325°C, 335°C, or even 350°C. In some embodiments, the cured compositions have a compression set of no more than 60%, 55%, 50%, 40%, 35%, 30%, or even 25% after 70 hours at 300°C, as measured according to ASTM D 395-03 Method B and ASTM D 1414-94 at an initial deflection of 25%. In some embodiments, the cured compositions have a compression set of no more than 80%, 70%, 60%, 55%, 50%, or even 45% after 70 hours at 335°C, as measured according to ASTM D 395-03 Method B and ASTM D 1414-94 at an initial deflection of 25%. In some embodiments, the compositions of the present disclosure maintain article integrity when exposed to elevated temperatures, e.g., the cured article does not melt. Although not wishing to be bound by theory, it is believed that the presence of the additive according to Formula II helps maintain crosslinking of the cured article when exposed to elevated temperatures.

[0081] Example

[0082] Unless otherwise indicated, all parts, percentages, ratios, etc. in the examples and the rest of the specification are by weight, and all materials are commercially available, for example, from Sigma-Aldrich Chemical Company, Milwaukee, WI, USA, or are known to those skilled in the art, unless otherwise indicated or obvious not to be the case.

[0083] The following abbreviations are used in this section: g = gram, lb = pound, cm = centimeter, min = minute, h = hour, N = Newton, dNm = Newton meter, MV = Mooney viscosity, ° C = Celsius, ° F = Fahrenheit, PSI = pounds per square inch, MPa = megapascals, mol = mole. Abbreviations of materials used in this section and descriptions of the materials are provided in Table 1.

[0084] Table 1 .

[0085]

[0086] Preparation Example 1: BF6Phth

[0087] In a three-necked 500 mL reaction flask, 50.0 g (0.289 mol) of 4-nitrophthalonitrile, 48.55 g (0.144 mol) of 4,4'-(hexafluoroisopropylidene)diphenol, and 49.9 g (0.361 mol) of anhydrous K 2 CO 3 And 225g of dry DMSO. The reaction solution is heated to 70°C and mechanically stirred with bubbling nitrogen for 3.5h. Stirring is stopped and the reaction salt is settled to the bottom of the container. Some reaction products have begun to crystallize from the reaction liquid. The reaction solution liquid and product are decanted from the reaction salt into a stirred cooling mixture of 250g 80 / 20 methanol / water (by mass). Additional products are crystallized from the DMSO / methanol / water solution. The reaction salt is washed with 25g DMSO, and the washed DMSO is decanted into the stirred DMSO / methanol / water solution. The product solid is collected on a Buchner funnel and washed with methanol, water and methanol. The solid is collected in an aluminum pan and dried in a convection oven at 140°C to remove methanol and water for 2h. The solid is further heated to 250°C for 15min, which melts the solid and discharges residual DMSO. The product melt is taken out from the oven and allowed to cool to ambient temperature. The product 79.0 g (92.9% yield) had a melt temperature of 231° C.-232° C. as measured by differential scanning calorimetry (DSC Q 2000, TA Instruments, New Castle, DE). The product was identified as bis(3,4-dicyanophenyl)ether of 4,4′-(hexafluoroisopropylidene)diphenol by infrared analysis and NMR and had a purity of >99%.

[0088] Preparation Example 2: Diphenyl Phth

[0089] 4-nitrophthalonitrile (48.8g) and 4,4'-biphenylene glycol (26.24g) are added to two-necked 500mL round-bottomed flasks. 200g of DMF is added to the flask. By stirring on a magnetic stirring plate with an egg-shaped stirring bar, 4-nitrophthalonitrile and 4,4'-biphenylene glycol are dissolved in DMF. DBU (53.6g) is added once. The bottleneck of the flask is sealed with a rubber septum, and a hot probe is inserted through a rubber septum. The solution is stirred with an egg-shaped stirring bar and heated to 70°C with a heating mantle. The flask solution is kept at 70°C for 2h. Allow the solution to cool to ambient temperature. The product is precipitated by being added to the methanol stirred by 500mL. The precipitate is collected under suction on a Buchner funnel with #4Whatman filter paper, and washed with 200mL of methanol, 200mL of water and 200mL of methanol. The collected solids were air dried overnight and further dried in a vacuum oven at 180° C. for 1 hour the next day. The solids 59.1 g (95.6% yield) had a melt temperature of 236° C. as measured by differential scanning calorimetry and were identified as 4,4′-bis(3,4-dicyanophenoxy)biphenyl by IR and NMR analysis.

[0090] Preparation Example 3: Resorc Phth

[0091] In a three-necked 500 mL reaction flask, 50.0 g (0.289 mol) of 4-nitrophthalonitrile, 15.90 g (0.144 mol) of resorcinol, and 49.9 g (0.361 mol) of anhydrous K 2 CO 3 And 175g dry DMSO.The reaction solution is heated to 70 ℃ and mechanically stirred for 3.5h with bubbling nitrogen.Stirring is stopped and the reaction salt is settled to the bottom of the container.The reaction solution liquid and product are decanted from the reaction salt into a stirred cooling mixture of 200g 80 / 20 methanol / water (by mass).The product is crystallized from the DMSO / methanol / water solution.The reaction salt is washed with 25g DMSO, and the washed DMSO is decanted into the stirred DMSO / methanol / water solution.The product solid is collected on a Buchner funnel and washed with methanol, water and methanol.The solid is collected in an aluminum pan and dried in a convection oven at 140 ℃ to remove methanol and water for 2h.The solid is further heated to 200 ℃ in a vacuum oven for 1h, which melts the solid and strips off the residual DMSO.The product melt is taken out from the oven and allowed to cool to ambient temperature. The product 47.3 g (90.4% yield) had a melt temperature of 185° C. as measured by differential scanning calorimetry on a TA Instruments DSC Q 2000. The product was identified as bis(3,4-dicyanophenyl)ether of resorcinol by IR analysis and NMR and had a purity of >99%.

[0092] Preparation Example 4: BPT Phth

[0093] In a three-necked 500 mL reaction flask, 50.0 g (0.289 mol) of 4-nitrophthalonitrile, 31.52 g (0.144 mol) of bisphenol T, and 49.9 g (0.361 mol) of anhydrous K 2 CO 3 And 225g of dry DMSO.The reaction solution is heated to 70°C and mechanically stirred for 3.5h with bubbling nitrogen.Stirring is stopped and the reaction salt is settled to the bottom of the container.The reaction solution liquid and product are decanted from the reaction salt into a stirred cooling mixture of 250g 80 / 20 methanol / water (by mass).Product is crystallized from the DMSO / methanol / water solution.The reaction salt is washed with 25g DMSO, and the washed DMSO is decanted into the stirred DMSO / methanol / water solution.The product solid is collected on a Buchner funnel and washed with methanol, water and methanol.The solid is collected in an aluminum pan and dried in a convection oven at 140°C to remove methanol and water for 2h.The solid is further heated to 200°C in a vacuum oven for 1h, which melts the solid and strips off the residual DMSO.The product melt is taken out from the oven and allowed to cool to ambient temperature. The product 60.6 g (89.2% yield) had a melt temperature of 178° C. as measured by differential scanning calorimetry on a TA Instruments DSC Q 2000. The product was identified as bis(3,4-dicyanophenyl)ether of bisphenol T by IR analysis and NMR and had a purity of >99%.

[0094] Samples were made in 100 g polymer batches by compounding on a two-roll mill the materials in the amounts listed in Table 1. For example, 0.7 g of catalyst was added to 100 g of fluoropolymer A in CE-1.

[0095] Curing rheology testing was performed using uncured, compounded samples using a rheometer available from Alpha technologies, Hudson, OH under the trade designation PPA 2000, according to ASTM D 5289-93a at 177°C, no preheat, 15 minutes elapsed time, and 0.5 degrees arc. The plateau or maximum torque (M) was not reached. H ) is the minimum torque (M) obtained during the specified time period L ) and the maximum torque. The torque reaching M L +0.5(M H -M L ) value (t'50) and the torque reaches M L +0.9(M H -M L) time, and the value of the tan d curve at maximum torque (tanδM H ). The results are reported in Table 3.

[0096] O-rings (214, AMS AS568) were molded at 177°C for 15 min. The press-cured O-rings were post-cured under one of two conditions: (A) 250°C for 16 h, or (B) ramped from room temperature to 150°C in 2 h and held at 150°C for 7 h, then ramped to 300°C in 2 h and held at 300°C for 2 h, and finally ramped to 320°C in 15 min and held for 15 min. The compression set resistance of the post-cured O-rings was tested at 300°C, 325°C, and 335°C for 70 h at an initial deflection of 25% according to ASTM D 395-03 Method B and ASTM D 1414-94. The results are reported in percentage in Table 4.

[0097] Table 2.

[0098]

[0099] Table 3 .

[0100]

[0101] Table 4 .

[0102]

[0103] FT-IR analysis

[0104] CE-1 and EX-2 were analyzed in transmission by Fourier transform infrared (FT-IR) spectroscopy (Perkin Elmer FT-IR Frontier spectrometer, Waltham, MA). A sample (6 g to 8 g) of the uncured compound was placed in a PPA 2000 rheometer and cured at 177°C for 15 minutes to form a pressurized cured disk. The disk was then post-cured according to the conditions (B) described above for the O-ring. An initial IR spectrum of the post-cured disk was obtained. The disk was then placed on a stainless steel plate and heat aged at 335°C for 70 hours. The heat aged sample was allowed to cool for 30 minutes before obtaining an IR spectrum.

[0105] Data analysis of absorbance spectra was performed using Perkin Elmer Spectrum IR software. For the peaks of interest, a baseline was first established. For the CF overtone peak, a baseline was established from 2210 cm -1 -2750cm -1 Establish a baseline and by using 2210cm -1 and 2700cm -1 The peak area is determined by the endpoint of 1525 cm -1 and 1575cm -1 The baseline from the triazine peak was determined by using the 1525 cm -1 and 1575cm -1 The peak area is determined by using the endpoint of . The results are listed in Table 5.

[0106] Table 5 .

[0107]

[0108] CE-1 and EX-2 were prepared at the same thickness and had similar initial integrated peak areas for the CF overtone peak as observed in Table 5. CE-1 and EX-2 also had similar initial integrated peak areas for the triazine peak. However, upon heat aging, CE-1 appears to show a decrease in both the CF overtone and triazine peak areas, while the integrated peak area for EX-2 appears to be relatively unchanged, indicating retention of crosslinking sites, which may explain the unexpectedly good compression set data for the O-ring samples of the present disclosure.

[0109] Without departing from the scope and spirit of the present invention, foreseeable modifications and changes of the present invention will be apparent to those skilled in the art. The present invention should not be limited to the embodiments shown in this application for illustrative purposes. If there is any conflict or contradiction between the disclosure in this specification written and any document incorporated herein by reference, then the written specification will prevail.

Claims

1. A composition comprising (i) an uncured highly fluorinated amorphous polymer comprising nitrile groups, wherein at least 80 mol % of the hydrogen atoms of the polymer backbone of the highly fluorinated amorphous polymer have been substituted by fluorine atoms; (ii) Contains organic A catalyst having a cation and an anion of formula I: wherein each R and R' is independently H, halogen, alkyl, aryl, aralkyl or cycloalkyl, and they may also be halogenated, fluorinated or perfluorinated, optionally wherein each R group or R' group may independently contain one or more heteroatoms; wherein two or more of the R groups and R' groups may together form a ring, provided that R' cannot be halogen; and (iii) Additives containing compounds of formula II Where X 1 and X 2 is independently selected from O or S, and L comprises at least one multivalent six-membered aromatic hydrocarbon group.

2. The composition of claim 1, wherein each R is F and R' is selected from the group consisting of H, phenyl, methoxyphenyl, toluoyl, phenoxy, fluorophenyl, trifluoromethylphenyl and CF3.

3. A composition according to any one of the preceding claims, wherein Formula I comprises at least one of 2-phenyl-1,1,1,3,3,3-hexafluoroisopropionic acid tetraalkylammonium, 1,1,1,3,3,3-hexafluoroisopropionic acid tetraalkylammonium, 2-phenyl-1,1,1,3,3,3-hexafluoroisopropionic acid tetrabutylphosphonium, 1,1,1,3,3,3-hexafluoroisopropionic acid tetrabutylphosphonium, 2-methoxyphenyl-1,1,1,3,3,3-hexafluoroisopropionic acid tetrabutylphosphonium or 2-p-toluoyl-1,1,1,3,3,3-hexafluoroisopropionic acid tetrabutylphosphonium.

4. The composition according to any one of the preceding claims, wherein at least 95 mol % of the hydrogen atoms of the polymer backbone of the uncured highly fluorinated amorphous polymer have been substituted with fluorine atoms.

5. The composition according to any one of the preceding claims, wherein the uncured highly fluorinated amorphous polymer comprises repeating units derived from a perfluorinated monomer comprising nitrile groups, tetrafluoroethylene (TFE) and at least one comonomer selected from the group consisting of perfluoroalkyl vinyl ether (PAVE) and perfluoroalkyl allyl ether (PAAE).

6. The composition of any one of the preceding claims, wherein the uncured highly fluorinated amorphous polymer comprises at least 1 mol% and no more than 5 mol% nitrile groups.

7. The composition of any one of the preceding claims, wherein the composition comprises at least 0.05 wt% to at most 5 wt% of the catalyst.

8. A composition according to any one of the preceding claims, wherein the composition comprises at least 0.05 wt% to at most 9 wt% of the compound according to formula (II).

9. A composition according to any one of the preceding claims, wherein L is a divalent, trivalent or tetravalent group.

10. A composition according to any one of the preceding claims, wherein L is or Where R 1 is selected from the group consisting of methyl, methoxy, ethyl and ethoxy groups, and R 2 Selected from the group consisting of methyl, methoxy, ethyl and ethoxy groups.

11. The composition according to any one of claims 1 to 10, wherein L is as well as Where R 4 is selected from the group consisting of a bond, -S-, -O-, -C(CF3)2-, -C(CH3)2-, -CH2-, -SO2-, -C(=O)-, and -C(CH3)2-C6H4-C(CH3)2-; each R 1 are independently selected from the group consisting of methyl, methoxy, ethyl and ethoxy groups, and each R 2 Independently selected from the group consisting of methyl, methoxy, ethyl and ethoxy groups.

12. The composition of any one of the preceding claims, wherein the composition further comprises a filler, wherein the filler is at least one of carbon black or polytetrafluoroethylene.

13. An article comprising a cured elastomer derived from the composition of any one of claims 1 to 12.

14. The article of claim 13, wherein the article has a compression set of no greater than 80% after 70 hours at 335°C.

15. A method of making a highly fluorinated elastomer, the method comprising: (a) combining the following to form a mixture: (i) a highly fluorinated amorphous polymer comprising nitrile groups, wherein at least 80 mol % of the hydrogen atoms of the polymer backbone of the highly fluorinated amorphous polymer have been replaced by fluorine atoms; (ii) an organic A catalyst having a cation and an anion of formula I: wherein each R and R' is independently H, halogen, alkyl, aryl, aralkyl or cycloalkyl, and they may also be halogenated, fluorinated or perfluorinated, optionally wherein each R group or R' group may independently contain one or more heteroatoms; wherein two or more of the R groups and R' groups may together form a ring, provided that R' cannot be halogen; and (iii) an additive comprising a compound of formula II Where X 1 and X 2 is independently selected from O or S, and L comprises at least one multivalent six-membered aromatic hydrocarbon group.

16. The method according to claim 15, further comprising (b) molding the article at a temperature suitable for pressurized curing to form a molded article; and (c) contacting the molded article with a non-isothermal thermal cycle.

17. The method of claim 16, wherein the non-isothermal thermal cycle comprises a final ramp to a temperature of at least 300°C in less than 1 hour.

18. Use of a catalyst and an additive for curing a highly fluorinated amorphous polymer containing nitrile groups, wherein at least 80 mol % of the hydrogen atoms of the polymer backbone of the highly fluorinated amorphous polymer have been replaced by fluorine atoms; the catalyst comprising an organic The cation and anion of formula I: wherein each R and R' is independently H, halogen, alkyl, aryl, aralkyl or cycloalkyl, and they may also be halogenated, fluorinated or perfluorinated, optionally wherein each R group or R' group may independently contain one or more heteroatoms; wherein two or more of the R groups and R' groups may together form a ring, provided that R' cannot be halogen; and The additive comprises a compound of formula II Where X 1 and X 2 is independently selected from O or S, and L comprises at least one multivalent six-membered aromatic hydrocarbon group.

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