TECHNICAL FIELD

[0001] Curing of compositions comprising a partially fluorinated amorphous

fluoropolymer with a curing agent comprising a terminal olefin with at least one olefinic hydrogen and a nucleophilic group are disclosed.

SUMMARY [0002] There is a desire to identify a novel curing system for partially fluorinated amorphous fluoropolymers.

[0003] In one aspect, a curable partially fluorinated polymer is disclosed comprising:

(i) a partially fluorinated amorphous fluoropolymer, wherein the partially fluorinated amorphous fluoropolymer comprises carbon-carbon double bonds or is capable of forming carbon-carbon double bonds along the partially fluorinated amorphous fluoropolymer chain;

(ii) 1 to 10 millimoles of a curing agent per 100 parts of the partially fluorinated amorphous fluoropolymer wherein the curing agent is of the formula CXiX2=CX3-L-M, wherein Xi, X ₂ , and X ₃ are independently selected from H, CI, and F and at least one of Xi, X ₂ , and X ₃ is H; L is a bond or a linking group; and M is a nucleophilic group;

(iii) an acid acceptor; and

(iv) an organoonium compound.

[0004] In another aspect, an article comprising the cured composition described above is disclosed.

[0005] In yet another aspect a method of making a partially fluorinated elastomer is disclosed comprising curing the curable partially fluorinated polymer composition disclosed above.

[0006] The above summary is not intended to describe each embodiment. The details of one or more embodiments of the invention are also set forth in the description below. Other features, objects, and advantages will be apparent from the description and from the claims. DETAILED DESCRIPTION

[0007] As used herein, the term

"a", "an", and "the" are used interchangeably and mean one or more; and

"and/or" is used to indicate one or both stated cases may occur, for example A and/or B includes, (A and B) and (A or B);

"backbone" refers to the main continuous chain of the polymer;

"crosslinking" refers to connecting two pre-formed polymer chains using chemical bonds or chemical groups;

"cure-site" refers to functional groups, which may participate in crosslinking; and "interpolymerized" refers to monomers that are polymerized together to form a polymer backbone.

Also herein, recitation of ranges by endpoints includes all numbers subsumed within that range (e.g., 1 to 10 includes 1.4, 1.9, 2.33, 5.75, 9.98, etc.).

[0008] Also herein, recitation of "at least one" includes all numbers of one and greater (e.g., 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.).

[0009] In the present disclosure, it has been found that a partially fluorinated amorphous fluoropolymer such as those disclosed herein can be cured with a curing agent comprising a terminal olefin with at least one olefinic hydrogen along with an acid acceptor and an onium compound.

[0010] Fluoropolymer

[0011] The amorphous fluoropolymers of the present disclosure are partially fluorinated polymers. As disclosed herein, an amorphous partially fluorinated polymer is a polymer comprising at least one carbon-hydrogen bond and at least one carbon-fluorine bond on the backbone of the polymer. In one embodiment, the amorphous partially fluorinated polymer is highly fluorinated, wherein at least 60, 70, 80, or even 90% of the polymer backbone comprises C-F bonds.

[0012] The amorphous fluoropolymer of the present disclosure also comprises carbon- carbon double bonds and/or is capable of forming carbon-carbon double bonds along the polymer chain. In one embodiment, the partially fluorinated amorphous fluoropolymer comprises carbon-carbon double bonds along the backbone of the partially fluorinated amorphous fluoropolymer or is capable of forming carbon-carbon double bonds along the backbone of the partially fluorinated amorphous fluoropolymer. In another embodiment, the partially fluorinated amorphous fluoropolymer comprises carbon-carbon double bonds or is capable of forming carbon-carbon double bonds in a pendent group off of the backbone of the partially fluorinated amorphous fluoropolymer.

[0013] The fluoropolymer capable of forming carbon-carbon double bonds means that the fluoropolymer contains units capable of forming double bonds. Such units include, for example, two adjacent carbons, along the polymer backbone or pendent side chain, wherein a hydrogen is attached to the first carbon and a leaving group is attached to the second carbon. During an elimination reaction (e.g., thermal reaction, and/or use of acids or bases), the leaving group and the hydrogen leave forming a double bond between the two carbon atoms. An exemplary leaving group includes: a halide, an alkoxide, a hydroxide, a tosylate, a mesylate, an amine, an ammonium, a sulfide, a sulfonium, a sulfoxide, a sulfone, and combinations thereof. Also contemplated would be a

fluoropolymer comprising adjacent carbons either having both bromine or both iodine atoms attached resulting in the leaving of Br ₂ or I ₂ .

[0014] The amorphous fluoropolymer comprises a plurality of these groups (carbon- carbon double bonds or groups capable of forming double bonds) to result in a sufficient cure. Generally, this means at least 0.1, 0.5, 1, 2, or even 5 mol % at most 7, 10, 15, or even 20 mol % (i.e., moles of these carbon-carbon double bonds or precursors thereof per mole of polymer).

[0015] In one embodiment, the amorphous partially fluorinated polymer is derived from at least one hydrogen containing monomer such as vinylidene fluoride.

[0016] In one embodiment, the amorphous fluoropolymer comprises adjacent

copolymerized units of vinylidene fluoride (VDF) and hexafluoropropylene (HFP);

copolymerized units of VDF (or tetrafluoroethylene) and a fluorinated comonomer capable of delivering an acidic hydrogen atom to the polymer backbone, such as trifluoroethylene; vinyl fluoride; 3,3,3-trifluoropropene-l ; pentafluoropropene (e.g., 2- hydropentafluoropropylene and 1 -hydropentafiuoropropylene); 2,3,3, 3-tetrafiuoropropene; and combinations thereof

[0017] In some embodiments, small amounts (e.g., less than 10, 5, 2, or even 1 wt%) of additional monomers may be added so long as the amorphous fluoropolymer is able to be cured using the curing agent disclosed herein. [0018] In one embodiment, the amorphous fluoropolymer is additionally derived from a hydrogen containing monomer including: pentafluoropropylene (e.g., 2- hydropentafluropropylene), propylene, ethylene, isobutylene, and combinations thereof.

[0019] In one embodiment, the amorphous fluoropolymer is additionally derived from a perfluorinated monomer. Exemplary perfluorinated monomers include:

hexafluoropropene; tetrafluoroethylene; chlorotrifluoroethylene; perfluoro(alkylvinyl ether) such as perfluoromethyl vinyl ether,

CF2=CFOCF ₂ OCF2CF ₂ CF3, and

perfluoro(alkylallyl ether) such as perfluoromethyl allyl ether, perfluoro(alkyloxyallyl ether) such as perfluoro-4,8-dioxa-l-nonene (i.e.,

CF2=CFCF ₂ OCF ₂ )30CF3], and combinations thereof.

[0020] Exemplary types of polymers include those comprising interpolymerized units derived from (i) vinylidene fluoride, tetrafluoroethylene, and propylene; (ii) vinylidene fluoride, tetrafluoroethylene, ethylene, and perfluoroalkyl vinyl ether, such as

perfluoro(methyi vinyl ether); (iii) vinylidene fluoride with hexafluoropropylene; (iv) hexafluoropropylene, tetrafluoroethylene, and vinylidene fluoride; (v)

hexafluoropropylene and vinylidene fluoride, (vi) vinylidene fluoride and perfluoroalkyl vinyl ether; (vii) vinylidene fluoride, tetrafluoroethylene, and perfluoroalkyl vinyl ether, (viii) vinylidene fluoride, perfluoroalkyl vinyl ether, hydropentafluoroethylene and optionally, tetrafluoroethylene; (ix) tetrafluoroethylene, propylene, and 3,3,3- trifluoropropene; (x) tetrafluoroethylene, and propylene; (xi) ethylene, tetrafluoroethylene, and perfluoroalkyl vinyl ether, and optionally3,3,3-trifluoropropylene; (xii) vinylidene fluoride, tetrafluoroethylene, and perfluoroalkyl allyl ether, (xiii) vinylidene fluoride and perfluoroalkyl allyl ether; (xiv) ethylene, tetrafluoroethylene, and perfluoroalkyl vinyl ether, and optionally3,3,3-trifluoropropylene; (xv) vinylidene fluoride, tetrafluoroethylene, and perfluoroalkyl allyl ether, (xvi) vinylidene fluoride and perfluoroalkyl allyl ether; (xvii) vinylidene fluoride, tetrafluoroethylene, and perfluoroalkyloxyallyl ether, (xviii) vinylidene fluoride and perfluoroalkyloxyallyl ether; (xiv) vinylidene fluoride,

tetrafluoroethylene, and perfluoroalkyloxyallyl ether, (xv) vinylidene fluoride and perfluoroalkyloxyallyl ether; and (xvi) combinations thereof.

[0021] Advantageously, by using the curing agent disclosed herein, the amorphous fluoropolymer of the present disclosure can be cured without the need for pendent bromine or iodine cure sites. Often, the iodine and bromine-containing cure site monomers, which are polymerized into the fluoropolymer and/or the chain ends, can be expensive among other things. However, in one embodiment, the partially fluorinated amorphous polymer comprises iodine and/or bromine cure sites, which can be used, for example, to enhance the cure of the fluoropolymer.

[0022] In one embodiment the partially fluorinated amorphous polymer is further derived from a bromine and/or iodine-containing cure site monomer capable of participating in a peroxide curing reaction.

[0023] Such bromine and/or iodine-containing cure site monomers include:

(a) bromo- or iodo- (per)fluoroalkyl-(per)fluorovinylethers having the formula:

Z-Rf -0-CX=CX ₂

wherein each X may be the same or different and represents H or F, Z is Br or I, Rf is a (per)fluoroalkylene Ci-Ci ₂ , optionally containing chlorine and/or ether oxygen atoms; for example: BrCF ₂ -0-CF=CF ₂ , BrCF ₂ CF ₂ -0-CF=CF ₂ , BrCF ₂ CF ₂ CF ₂ -0-CF=CF ₂ , CF ₃ CFBrCF ₂ -0-CF=CF ₂ , ICF ₂ CF ₂ CH=CH ₂ , ICF ₂ CF ₂ CF ₂ -0-CF=CF ₂ , and the like;

(b) bromo- or iodo perfluoroolefins such as those having the formula:

wherein each X independently represents H or F, Z' is Br or I, Rf is a perfluoroalkylene Ci-Ci ₂ , optionally containing chlorine atoms and r is 0 or 1 ; for instance: bromotrifluoroethylene, 4-bromo-perfluorobutene-l, and the like; or bromofluoroolefins such as l-bromo-2,2-difluoroethylene and 4-bromo-3,3,4,4-tetrafluorobutene-l ;

(c) non-fluorinated bromo- olefins such as vinyl bromide and 4-bromo-l-butene.

[0024] In one embodiment, the amorphous fluoropolymer is polymerized in the presence of a bromine and/or iodine-containing chain transfer agent, as is known in the art, such as those having the formula RfPx, wherein P is Br or I, preferably I, Rf is an x-valent alkyl radical having from 1 to 12 carbon atoms, which, optionally may also contain chlorine atoms. Typically, x is 1 or 2. Useful chain transfer agents include perfluorinated alkyl monoiodide, perfluorinated alkyl diiodide, perfluorinated alkyl monobromide,

perfluorinated alkyl dibromide, and combinations thereof. Specific examples include CF ₂ Br ₂ , Br(CF ₂ ) ₂ Br, Br(CF ₂ ) ₄ Br, CF ₂ ClBr, CF ₃ CFBrCF ₂ Br, I(CF ₂ )J wherein n is an integer from 3-10 (e.g., I(CF ₂ ) ₄ I), and combinations thereof. [0025] In one embodiment, the amorphous fluoropolymer is substantially free of I, or Br, wherein the amorphous fluoropolymer comprises less than 0.1, 0.05, 0.01, or even 0.005 mole percent relative to the total polymer.

[0026] In one embodiment, the amorphous fluoropolymer of the present disclosure is non- grafted, meaning that it does not comprise pendant groups including vinyl, allyl, acrylate, amido, sulfonic acid salt, pyridine, carboxylic ester, carboxylic salt, hindered silanes that are aliphatic or aromatic tri-ethers or tri-esters. In one embodiment, the amorphous fluoropolymer does not comprise a monophenol graft.

[0027] Curing Agent

[0028] The curing agent of the present disclosure is a compound containing at least one terminal olefin with at least one olefinic hydrogen. In one embodiment, the curing agent of the present disclosure is represented by Formula I:

wherein Xi, X ₂ , and X ₃ are independently selected from H, CI, and F and at least one of Xi, X ₂ , and X ₃ is H; L is a bond or a linking group; and M is a nucleophilic group.

[0029] L represents a single bond or a linking group. The linking group can be a catenated O, S, or N atom (e.g., an ether linkage), or a divalent organic group, optionally comprising a catenated heteroatom (e.g., O, S or N), and/or optionally substituted. The divalent organic group may be linear, branched, or cyclic. The divalent organic group may be aromatic or aliphatic. The divalent organic group may be non-fluorinated (comprising no fluorine atoms), partially fluorinated (comprising at least one C-H bond and at least one C- F bond, or perfluorinated (comprising no C-H bonds and at least one C-F bond).

[0030] In one embodiment, the divalent organic group is -(CH ₂ ) _n (0)m- P-(Rf) _P -(P)q - where n is an integer from 1-10; m is 0 or 1; P is selected from at least one of: an aromatic, a substituted aromatic, and (CH ₂ ) _n where n is an integer from 1-10; Rf is selected from at least one of: (CF ₂ ) _n where n is an integer from 1-10, and C(CF ₃ ) ₂ wherein Rf may be cyclic or aliphatic and/or contain at least one catenated heteroatoms such as O, S and N; p is 0 or 1; and q is 0 or 1. Exemplary divalent organic groups include: -CH ₂ -C6H4(OCH ₃ )-, -CH ₂ -0-CH ₂ (CF ₂ ) ₄ -CH ₂ - and -CH ₂ -0-C ₆ H4-C(CF ₃ ) ₂ -C ₆ H4-, and -CH ₂ -0-C ₆ H ₄ -C(CF ₃ ) ₂ - C ₆ H ₄ -0-CH ₂ -. [0031] M is nucleophilic group, meaning it comprises an unshared electron pair. An exemplary nucleophilic group includes: an alcohol (-OH), an amine (- H2, - HR, and - NRR' where R and R' are an organic group), a thiol (-SH), and carboxylic acid (-COOH).

[0032] In one embodiment, the curing agent comprises at least one nonfluorinated terminal olefin group, in other words, the olefin does not comprise any fluorine atoms. In one embodiment, the curing agent comprises a non-aromatic terminal olefin and/or non- aromatic alcohol.

[0033] Exemplary curing agent include:

and combinations thereof, where n is independently selected from an integer from 1 to 50, 1 to 20, 1 to 10, or even 2 to 10, and Rf is a fluorinated alkyl group. Rf may be partially or fully fluorinated. In one embodiment, Rf may comprise catenated heteroatoms such as O, S, or N. Rf may be linear or branched, saturated or unsaturated. In one embodiment Rf is a CI to C12 fluorinated alkyl group (optionally, perfluorinated).

[0034] The curing agent should be used in quantities substantial enough to cause the amorphous fluoropolymer to cure, as indicated by a rise in torque on a moving die rheometer. For example, at least 1, 1.5, 2, 2.5, 3, or even 4 or more millimoles per 100 parts of the amorphous fluoropolymer is used. If too little curing agent is used, the amorphous fluoropolymer will not cure. For example, no more than 20, 15, 10, or even 8 millimoles of the curing agent per 100 parts of the amorphous fluoropolymer is used. If too much curing agent is used, the amorphous fluoropolymer can become brittle.

[0035] In one embodiment, the curable partially fluorinated polymer composition is substantially free of a monophenol, meaning that the composition comprising the amorphous fluoropolymer comprises less than 0.1, 0.01, or even 0.001 % moles of monophenol versus the moles of amorphous fluoropolymer.

[0036] Acid Acceptor

[0037] In one embodiment, an acid acceptor is used in the present disclosure, such acid acceptors include organic, inorganic, or blends of thereof. Examples of inorganic acceptors include magnesium oxide, lead oxide, calcium oxide, calcium hydroxide, dibasic lead phosphate, zinc oxide, barium carbonate, strontium hydroxide, calcium carbonate, hydrotalcite, etc. Organic acceptors include amines, epoxies, sodium stearate, and magnesium oxalate. Particularly suitable acid acceptors include calcium hydroxide, magnesium oxide and zinc oxide. Blends of acid acceptors may be used as well. The amount of acid acceptor will generally depend on the nature of the acid acceptor used. [0038] In one embodiment, at least 0.5, 1, 2, 3, or even 4 parts of the acid acceptor per 100 parts of the amorphous fluoropolymer are used. In one embodiment, no more than 10, 7, or even 5 parts of the acid acceptor per 100 parts of the amorphous fluoropolymer are used.

[0039] Onium Compound

[0040] In one embodiment, an organo onium compound is added to the composition as a phase transfer catalyst to assist with the crosslinking of the amorphous fluoropolymer and/or may be used to generate the double bonds on the fluoropolymer through

dehydrofluorination. Such organo onium compounds include quaternary ammonium hydroxides or salts, quaternary phosphonium hydroxides or sails, and ternary sulf onium hydroxides or salts.

[0041] Briefly, a phosphonium and ammonium salts or compounds comprise a central atom of phosphorous or nitrogen, respectively, covalently bonded to four organic moieties by means of a carbon-phosphorous (or carbon-nitrogen) covalent bonds and is ionicaliy associated with an anion. The organic moieties can be the same or different.

[0042] Briefly, a sulfonium compound is a sulfur-containing organic compound in which at least one sulfur atom is covalently bonded to three organic moieties having from 1 to 20 carbon atoms by means of carbon-sulfur covalent bonds and is ionicaliy associated with an anion. The organic moieties can be the same or different. The sulfonium compounds may have more than one relatively positive sulfur atom, e.g. [(C& 1 ί.-Φ S ⁺ (CH ₂ ) ₄ S ^÷ (C6H5)2]2C , and two of the carbon-sulfur covalent bonds may be between the carbon atoms of a divalent organic moiety, i.e., the sulfur atom may be a heteroatom in a cyclic structure.

[0043] The organo onium compounds suitable for use in this disclosure are known and are described in the art. See, for example, U.S. Pat. Nos. 5,262,490 (Kolb et al.) and 4,912, 171 (Grootaert et al), herein incorporated by reference.

[0044] Exemplary organo onium compounds include: C3 symmetrical

tetraalkylammonium salts, unsymmetrical tetraalkylammonium salts wherein the sum of alky] carbons is between 8 and 24 and benzyltrialkyj ammonium salts wherein the sum of alkyl carbons is between 7 and 19 (for example tetrabutylammonium bromide,

tetrabutyl ammonium chloride, benzyitributyiammonium chloride,

benzyltriethyiammonium chloride, tetrabutylammonium hydrogen sulfate and

tetrabutylammonium hydroxide, phenyltrimethylammonium chloride,

tetrapentylammonium chloride, tetrapropyl ammonium bromide, tetrahexylammonim chloride, and tetraheptylammonium bromidetetramethy!ammonium chloride); quaternary phosphonium salts, such as tetrabutylphosphonium salts, tetraphenylphosphonium chloride, benzyitriphenylphosphonium chloride, tributylaliylphosphonium chloride, tributylbenzyl phosphonium chloride, tributyl-2-methoxypropyl.phosphonium chloride, benzyldiphenyl(dirnethylamino)phosphonium chloride, 8-benzyl-l ,8-diazobicyc!o[5.4.0]7- undeceniuni chloride, benzyltris(dimethylamino)phosphonium chloride, and

bis(benzyldipheny]phosphine)iminiurn chloride. Other suitable organo onium compounds include 1 ,8-diazabicyclo[5. .0]undec-7-ene and l,5-diazabicyclo[4.3.0]non-5-ene.

Phenol ate is a preferred anion for the quaternary ammonium and phosphonium salts.

[0045] In one embodiment, the organo onium compound is used between 1 and 5 millimoles per 100 parts of the amorphous fluoropolymer (mmhr).

[0046] Free Radical Source

[0047] In one embodiment, the curable composition comprises a free radical source, used to initiate the cure. Such free radical sources include peroxides such as organic peroxides. In many cases it is preferred to use a tertiary butyl peroxide having a tertiary carbon atom attached to a peroxy oxygen.

[0048] Exemplary peroxides include: 2,5-dimethyl-2,5-di(t-butylperoxy)hexane; dicumyl peroxide; di(2-t-butylperoxyisopropyl)benzene; dialkyl peroxide; bis (dialkyl peroxide); 2,5-dimethyl-2,5-di(tertiarybutylperoxy)3-hexyne; dibenzoyl peroxide; 2,4- dichlorobenzoyl peroxide; tertiarybutyl perbenzoate; a,a'-bis(t-butylperoxy- diisopropylbenzene); t-butyl peroxy isopropyl carbonate, t-butyl peroxy 2-ethylhexyl carbonate, t-amyl peroxy 2-ethylhexyl carbonate, t-hexylperoxy isopropyl carbonate, di[l,3-dimethyl-3-(t-butylperoxy)butyl] carbonate, carbonoperoxoic acid, Ο,Ο'- 1,3- propanediyl 00,00'-bis(l,l-dimethylethyl) ester, and combinations thereof.

[0049] The amount of free radical source used generally will be at least 0.1, 0.2, 0.4, 0.6, 0.8, 1, 1.2, or even 1.5; at most 2, 2.25, 2.5, 2.75, 3, 3.5, 4, 4.5, 5, or even 5.5 parts by weight per 100 parts of the amorphous fluoropolymer. In one embodiment, the curable composition is substantially free of a free radical source, in other words, less than 0.05 or even 0.01 parts by weight per 100 parts of the amorphous fluoropolymer.

[0050] A typical coagent is a compound that comprises a terminal unsaturation site, which is incorporated into the polymer during curing to assist with curing, typically peroxide curing. Exemplary coagents include: tri(methyl)allyl isocyanurate (TMAIC), triallyl isocyanurate (TAIC), tri(methyl)allyl cyanurate, poly-triallyl isocyanurate (poly-TAIC), triallyl cyanurate (TAC), xylylene-bis(diallyl isocyanurate) (XBD), N,N'-m-phenylene bismaleimide, diallyl phthalate, tris(diallylamine)-s-triazine, triallyl phosphite, 1,2- polybutadiene, ethyleneglycol diacrylate, diethyleneglycol diacrylate, and combinations thereof. Another useful coagent may be represented by the formula CH ₂ =CH-Rn-CH=CH ₂ wherein Rn may be a perfluoroalkylene of 1 to 8 carbon atoms. By using the curing agent disclosed herein, the amorphous fluoropolymers of the present disclosure can be cured without the use of these coagents. In other words, the curable composition is substantially free (less than 1, 0.5, or even 0.1 part per 100 parts per amorphous fluoropolymer% or even below detection) of a typical coagent. This can be advantageous because of the coagents expense, incompatibility with fluorinated polymers, and impact on processing (e.g., bleeding out of compositions, mold fouling).

[0051] The curable composition can also contain a wide variety of additives of the type normally used in the preparation of elastomeric compositions, such as pigments, fillers (such as carbon black), pore-forming agents, and those known in the art.

[0052] The curable amorphous fluoropolymer compositions may be prepared by mixing the amorphous fluoropolymer and the curing agent, along with the other components (e.g., the acid acceptor, the onium compound, the free radical source, and/or the additional additives) in conventional rubber processing equipment to provide a solid mixture, i.e. a solid polymer containing the additional ingredients, also referred to in the art as a

"compound". This process of mixing the ingredients to produce such a solid polymer composition containing other ingredients is typically called "compounding". Such equipment includes rubber mills, internal mixers, such as Banbury mixers, and mixing extruders. The temperature of the mixture during mixing typically will not rise above about 120°C. During mixing the components and additives are distributed uniformly throughout the resulting fluorinated polymer "compound" or polymer sheets. The

"compound" can then be extruded or pressed in a mold, e.g., a cavity or a transfer mold and subsequently be oven-cured. In an alternative embodiment curing can be done in an autoclave.

[0053] Curing is typically achieved by heat-treating the curable amorphous fluoropolymer composition. The heat-treatment is carried out at an effective temperature and effective time to create a cured fluoroelastomer. Optimum conditions can be tested by examining the cured fluoroelastomer for its mechanical and physical properties. Typically, curing is carried out at temperatures greater than 120°C or greater than 150°C. Typical curing conditions include curing at temperatures between 160°C and 210°C or between 160°C and 190°C. Typical curing periods include from 3 to 90 minutes. Curing is preferably carried out under pressure. For example pressures from 10 to 100 bar may be applied. A post curing cycle may be applied to ensure the curing process is fully completed. Post curing may be carried out at a temperature between 170°C and 250°C for a period of 1 to 24 hours.

[0054] The partially fluorinated amorphous fluoropolymer in the curable composition has a Mooney viscosity in accordance with ASTM D 1646-06 TYPE A by a MV 2000 instrument (available from Alpha Technologies, Ohio, USA) using large rotor (ML 1+10) at 121 °C. Upon curing, using the curing agent disclosed herein, the amorphous fluoropolymer becomes an elastomer, becoming a non-flowing fluoropolymer, and having an infinite viscosity (and therefore no measurable Mooney viscosity).

[0055] In one embodiment of the present disclosure, the cure system comprising the curing agent and amorphous fluoropolymer disclosed herein, may exhibit both the chemical resistance of a typical iodine/bromine and coagent containing peroxide cure system, while at the same time elevating the poor heat resistance of these conventional iodine or bromine containing fluoroelastomers, due to their lack of bromine or iodine and therefore resulting in a cured fluoropolymer having simultaneously sufficient heat and chemical resistance.

[0056] The cured fluoroelastomer is particularly useful as seals, gaskets, and molded parts in automotive, chemical processing, semiconductor, aerospace, and petroleum industry applications, among others.

[0057] Exemplary embodiments of the present disclosure include:

[0058] Embodiment 1. A curable partially fluorinated polymer composition comprising:

(i) a partially fluorinated amorphous fluoropolymer, wherein the partially fluorinated amorphous fluoropolymer comprises carbon-carbon double bonds or is capable of forming carbon-carbon double bonds along the partially fluorinated amorphous fluoropolymer chain;

(ii) 1 to 10 millimoles of a curing agent per 100 parts of the partially fluorinated amorphous fluoropolymer wherein the curing agent is of the formula CXiX2=CX3-L-M, wherein Xi, X ₂ , and X ₃ are independently selected from H, CI, and F and at least one of Xi, X ₂ , and X3 is H; L is a bond or a linking group; and M is a nucleophilic group;

(iii) an acid acceptor; and

(iv) an organo onium compound.

[0059] Embodiment 2. The curable partially fluonnated polymer composition of embodiment 1 wherein the partially fluorinated amorphous fluoropolymer comprises (i) adjacent copolymerized units of VDF and HFP; (ii) copolymerized units of VDF and a fluonnated comonomer having an acidic hydrogen atom; (iii) copolymerized units of TFE and a fluo inated comonomer having an acidic hydrogen atom; and (iv) combinations thereof.

[0060] Embodiment 3 , The curable partially fluorinated polymer composition of a embodiment 2 wherein the fluorinated comonomer having an acidic hydrogen atom is selected from: trifluoroethylene; vinyl fluoride; 3,3,3-trifluoropropene-l;

pentafluoropropene; and 2,3,3,3-tetrafluoropropene.

[0061] Embodiment 4. The curable partially fluorinated polymer composition of any one of the previous embodiments, wherein the partially fluorinated amorphous fluoropolymer is derived from (i) vinylidene fluoride, tetrafluoroethylene, and propylene; (ii) vinylidene fluoride, tetrafluoroethylene, ethylene, and perfluoroalkyl vinyl ether, such as

perfluoro(methyl vinyl ether); (iii) vinylidene fluoride with hexafluoropropylene; (iv) hexafluoropropylene, tetrafluoroethylene, and vinylidene fluoride; (v)

hexafluoropropylene and vinylidene fluoride, (vi) vinylidene fluoride and perfluoroalkyl vinyl ether; (vii) vinylidene fluoride, tetrafluoroethylene, and perfluoroalkyl vinyl ether, (viii) vinylidene fluoride, perfluoroalkyl vinyl ether, hydropentafluoroethylene and optionally, tetrafluoroethylene; (ix) tetrafluoroethylene, propylene, and 3,3,3- trifluoropropene; (x) tetrafluoroethylene, and propylene; (xi) ethylene, tetrafluoroethylene, and perfluoroalkyl vinyl ether, and optionally3,3,3-trifluoropropylene; (xii) vinylidene fluoride, tetrafluoroethylene, and perfluoroalkyl allyl ether, (xiii) vinylidene fluoride, and perfluoroalkyl allyl ether; (xiv) vinylidene fluoride, tetrafluoroethylene, and

perfluoroalkyloxyallyl ether, (xv) vinylidene fluoride and perfluoroalkyloxyallyl ether; (xvi) vinylidene fluoride, tetrafluoroethylene, and perfluoroalkyloxyallyl ether, (xv) vinylidene fluoride and perfluoroalkyloxyallyl ether; and (xvi) combinations thereof. [0062] Embodiment 5. The curable partially fluorinated polymer composition of any one of the previous embodiments, wherein the partially fluorinated amorphous fluoropolymer comprises carbon-carbon double bonds along the backbone of the partially fluorinated amorphous fluoropolymer or is capable of forming carbon-carbon double bonds along the backbone of the partially fluorinated amorphous fluoropolymer.

[0063] Embodiment 6. The curable partially fluorinated polymer composition of any one of the previous embodiments, wherein the nucleophilic group is selected from an alcohol, an amine, and a thiol.

[0064] Embodiment 7. The curable partially fluorinated polymer composition of any one of the previous embodiments, wherein the curing agent comprises a nonfluorinated terminal olefin group.

[0065] Embodiment 8. The curable partially fluorinated polymer composition of any one of the previous embodiments, wherein the curing agent comprises a non-aromatic alcohol.

[0066] Embodiment 9. The curable partially fluorinated polymer composition of any one of the previous embodiments, wherein the curable partially fluorinated polymer composition is substantially free of a monophenol.

[0067] Embodiment 10. The curable partially fluorinated polymer composition of any one of the previous embodiments, wherein the curing agent is selected from at least one of:

and combinations thereof, wherein n is an integer from 1 to 10.

[0068] Embodiment 11. The curable partially fluorinated polymer composition of any one of the previous embodiments, wherein the organo onium compound is selected from at least one of a phosphonium or a sulfonium.

[0069] Embodiment 12. The curable partially fluorinated polymer composition of any one of the previous embodiments, wherein the partially fluorinated amorphous fluoropolymer is further derived from a cure site monomer comprising at least one of I and Br.

[0070] Embodiment 13. The curable partially fluorinated polymer composition of any one of embodiments 1-11, wherein the fluoropolymer is substantially free of I, Br, and CI.

[0071] Embodiment 14. The curable partially fluorinated polymer composition of any one of the previous embodiments, wherein the acid acceptor is selected from at least one of magnesium oxide, lead oxide, calcium oxide, calcium hydroxide, dibasic lead phosphate, zinc oxide, barium carbonate, strontium hydroxide, calcium carbonate, and hydrotalcite.

[0072] Embodiment 15. The curable partially fluorinated polymer composition of any one of the previous embodiments, further comprising a free radical source.

[0073] Embodiment 16. The curable partially fluorinated polymer composition of embodiment 15, wherein the free radical source is selected from at least one of a peroxide.

[0074] Embodiment 17. The curable partially fluorinated polymer composition of embodiment 16, wherein the composition is substantially free of a cogent.

[0075] Embodiment 18. An article comprising the cured composition of any one of embodiments 1-17.

[0076] Embodiment 19. The method of making a partially fluorinated elastomer comprising:

providing the curable partially fluorinated polymer composition of any one of

embodiments 1- 17; and

curing the curable partially fluorinated polymer composition.

EXAMPLES

[0077] Advantages and embodiments of this disclosure are further illustrated by the following 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. In these examples, all percentages, proportions and ratios are by weight unless otherwise indicated.

[0078] All materials are commercially available, for example from Sigma-Aldrich

Chemical Company; Milwaukee, WI, or known to those skilled in the art unless otherwise stated or apparent.

[0079] These abbreviations are used in the following examples: phr = parts per hundred rubber; g

= grams, kg = kilograms; min = minutes; mol = mole; hr = hour, °C = degrees Celsius;, mL = milliliter; L = liter; mm= millimeter; kN= Kilo-Newtons; kPa = Kilo-Pascals; GC/MS = gas chromatography mass spectrometry; Pa = Pascal; psig = pounds per square inch; LC/UV= liquid chromatography ultraviolet detection; and phr = per hundred parts rubber (or amorphous polymer).

Materials

Name Description

(OFHDAE)

BF6MAE Terminal olefin, prepared as per "Curative Monoallyl Ether of

Bisphenol AF (BF6MAE)"

Peroxide Peroxide commercially available under the trade designation

"VAROX DBPH-50" from R.T. Vanderbilt Company, Inc.,

Norwalk, CT

Hydrotalcite An acid acceptor. Layered double hydroxide of general formula

Mg6Al2C03(OH)i6'4(H20), commercially available from Kyowa Chemical, Tokyo, JP under the trade designation "DHT-4A"

MgO An acid acceptor. Magnesium oxide powder commercially available from Akrochem Corp., Akron, Ohio under the trade designation "ELASTOMAG 170"

Ca(OH) ₂ An acid acceptor. Calcium hydroxide commercially available under the trade designation "Rhenofit CF" from

RheinChemie, Mannheim, Germany

[0080] Preparation of VDF/BTFE/MA31

[0081] Under oxygen-free condition a 4 liter kettle was charged with 3400 mL deionized water. 12g CF3-0-(CF ₂ )3-0-CFH-CF ₂ -COONH4 was added as emulsifier. After heating to 90 °C 40g tetrafluoroethene (TFE), 77g VDF, 3g 1-bromotrifluoroethene (BTFE) were added and 140g perfluoro-4,8-dioxa-l-nonene (MA31, prepared analogously to "PMEAE" in U.S. Pat. No.

5,891,965 Worm et al.) was added as preemulsion (described in WO200149752). The reaction was initiated with addition of l,4g ammonium peroxodisulphate (APS) dissolved in 280mL deionized water by continuously feeding. At 10 bar pressure and 90 °C 200g TFE, 380g VDF, 6.2g BTFE, 560g MA31 (as preemulsion) were fed over a period of 190 min. The resulting latex had a solid content of 27% and was coagulated with 12g MgCh. The resulting 1.1kg polymer was dried at 130 °C.

[0082] The composition of the resulted polymer was 13.5 mole % MV31, 69.7 mole% VDF, 16.1mole% TFE, and 0.7mole% BTFE. The glass transition temperature (by DSC) was Tg=-42 °C and Mooney-Viscosity (1+10', 121°C) was 51.

[0083] Curative Monoallyl Ether of Bisphenol AF (BF6MAE)

[0084] In a 3 -neck 2 liter round bottom flask equipped with a mechanical stirrer, condenser and a thermocouple was charged with 250g, 0.7mol of HO-C ₆ H4C(CF3)2C6H4- OH, 30g, 0.3mol allyl bromide, 5g, 0.02mol tetrabutyl ammonium bromide that was dissolved in 4g deionized (DI) water and 500g glyme. The solution was stirred and heated to 50°C. A solution of 16g, 0.3mol KOH dissolved in 18g DI water was added drop wise over 15 min resulting in a precipitate and a temperature increase to 62°C. The reaction was heated to 65°C for one hr before cooling to 25°C. The top glyme solution phase was removed and placed in a round bottom flask and rotary evaporated at 50°C/2 torr. This was followed by heating to 50°C at 0.13 kPa (1 torr) using a vacuum pump for one hour followed by the addition of 400g of chloroform and stirred slurry for 20 hrs. The slurry was filtered and the solution was rotary evaporated at 50°C/20 torr isolated 50g viscous oily product. A second chloroform extraction done to the solids gave 21g of additional oily product for a 76% yield. LC/UV analysis gave mole percent of the following: 66.8% CH2=CHCH2-OC6H4C(CF3)2C ₆ H4-OH, 6.6%

CH ₂ CH=CH ₂ , and 23.7% of HO-C ₆ H ₄ C(CF3) ₂ C6H4-OH. The isolation of allyl ether phenyl hexafluorofluoroisopropylidene phenol was done by flash chromatography (available under the trade designation "INTELLIFLASH 280", Analogix Co., Santa Clara, CA) with a silica gel column eluding first with heptane as the nonpolar solvent and ending with ethyl acetate as the polar solvent. LC/UV analysis gave 99.23 mole percent of CH ₂ =CHCH ₂ -OC6H ₄ C(CF3) ₂ C ₆ H4-OH. The material as synthesized was diluted in methanol to a 50% solids concentration in order to better facilitate the incorporation into the polymer.

[0085] Curative Allyl Ether of Octafluorohexane Diol (OFHDAE /CH ₂ =CHCH ₂ -

[0086] In a 3-neck 500 ml round bottom flask equipped with a mechanical stirrer, condenser and a thermocouple was charged with 50g, 0.19mol of HO-CH ₂ C4F8CH ₂ -OH (available from Exfluor Research Corporation, Round Rock, TX) and 150g of methyl-t- butyl ether. The solution was stirred and added a solution of 12g, 0.18mol KOH dissolved in 26g DI water followed by 2g, O.Olmol tetrabutyl ammonium bromide that was dissolved in 3g DI water. The solution was stirred and heated to 50°C and 22g, 0.18mol allyl bromide was added drop wise over 20 min and kept at 50°C for two hrs before cooling to 25°C.

[0087] The top methyl-t-butyl ether solution phase was removed and placed in a round bottom flask and evaporated at 50°C/1.33 kPa (10 torr), using a rotary evaporator. A charge of 55g of hexane to the product mixture and stirred to give two phases. The bottom phase was extracted with an additional 50g of hexane. The bottom phase was washed twice with chloroform to extract the desired product and filtered to remove insoluble starting diol. The chloroform solution was removed and placed in a round bottom flask and evaporated at 55°C/10torr using a rotary evaporator to isolate 19g product mixture. GC/MS analysis gave mole percent of the following: 84% CH ₂ =CHCH ₂ - OCH ₂ C ₄ F ₈ CH ₂ - OH, 12.5% CH ₂ =CHCH ₂ - OCH ₂ C ₄ F ₈ CH ₂ 0-CH ₂ CH=CH ₂ and 3.9% HO-CH ₂ C ₄ F ₈ CH ₂ - OH. The material as synthesized was diluted in methanol to a 50% solids concentration in order to better facilitate the incorporation into the polymer.

[0088] Preparation VDF/TFE/HFP

[0089] In a 2000 gallon (7570 L) kettle was charged 13,180 pounds (5978 kg) of DI water, 50 pounds (22.6 kg) of a 50% solution of potassium hydrogen phosphate in water, 2 pounds (0.9 kg) of hexamethyldisilane, and then the solution was heated to 160°F. Agitation was set at 100 rpm. The kettle was pressurized with 155 pounds (70 kg) of HFP, 38 pounds (17 kg) of VDF and 53 pounds (24 kg) of TFE to a pressure of 130 psig (896 kPa). The polymerization was initiated with 12 pounds (5 kg) of ammonium persulfate. As the reaction started the pressure was maintained at 130 psig (896 kPA) by adding VDF/TFE/HFP at a ratio of 1/0.739/1.330. The reaction temperature of 160°F (71 °C) was maintained. When 1726 pounds (783 kg) of VDF was added the HFP valve was closed and an additional amount of VDF and TFE was added at a ratio of VDF/TFE = 1.4/1 until 70 pounds (32 kg) of VDF was added. The latex was free of coagulum and had a solids content of approximately 28%. The polymer was isolated by coagulation with magnesium chloride, washed with DI water, and oven dried at 266°F (130°C) for until a moisture content of < 0.5 weight % was reached.

[0090] Preparation VDF/TFE/P#1

[0091] In a 2000 gallon (7570 L) kettle was charged 12,940 pounds (5869 kg) of DI water and 50 pounds (23 kg) of a 50% solution of potassium hydrogen phosphate in water, the solution was then heated to 160°F (71 °C). Agitation was set at 100 rpm. The kettle was pressurized with 189 pounds (86 kg) of VDF and 111 pounds (50 kg) of TFE to a pressure of 220 psig (1516 kPa). Then the polymerization was initiated with 60 pounds (27 kg) of ammonium persulfate. As the reaction started the pressure was maintained at 220 psig by adding VDF/TFE/propylene at a ratio of

1/1.885/0.394. The reaction temperature of 160°F (71 °C) was maintained. When 1487 pounds (674 kg) of VDF was added the VDF valve was closed and an additional amount of TFE and propylene was added at a ratio of TFE/P = 4: 1 until 40 pounds (18 kg) of TFE was added. The latex was free of coagulum and had a solids content of approximately 27%. The polymer was isolated by coagulation with magnesium chloride, washing with DI water, and drying at 280°F (138°C) until a moisture content of < 0.5 weight per cent was reached.

[0092] Methods

[0093] HARDNESS: [0094] Hardness Shore A (2") was measured on post cured samples according to ASTM D-2240-05 (2010) and as indicated in Table 2 and 3.

[0095] TENSILE STRENGTH AND ELONGATION:

[0096] Tensile strength and elongation were determined on post cured samples using a mechanical tensile tester (Instron, Norwood, MA) with a 1 kN load cell in accordance with DIN 53504 (2009) (S2 DIE) at a constant cross head displacement rate of 200 mm/min as indicated in Table 2 and 3.

[0097] CURE RHEOLOGY

[0098] 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 °C, no pre-heat, 30 min 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 (MH) was obtained were measured. Also measured were the time for the torque to increase 2 units above ML (t _s 2), the time for the torque to reach a value equal to ML + 0.5(MH - ML), (t'50), and the time for the torque to reach ML +

0.9(MH - ML), (t'90) as well as the tan(delta) at ML and MH. Tan(delta) is equal to the ratio of the tensile loss modulus to the tensile storage modulus (lower tan(delta) means more elastic).

[0099] O-RING MOLDING AND COMPRESSION SET

[00100] O-rings having a cross-section thickness of 0.139 inch (3.5 mm) were molded (15 min cure at 177 °C) followed by a postcure in air for 16 hrs at 232°C. The O- rings were subjected to compression set testing following a similar method as described in ASTM 395-89 method B (analyzed in triplicate), with 25 % initial deflection at variable time and temperature as per Tables 2 and 3.

[00101] For each of the Examples (E) and Comparative Examples (CE), the amounts of the components used (with the amount per 100 parts of rubber listed in parenthesis) as shown in Table 1 were compounded on a two-roll mill. Cure Rheology evaluations were carried out for each Example and Comparative Example using the test method described above. The results are shown in Table 2 and 3. O-rings were molded, cured (press cured for 15 min at 177 °C and postcured for 16 hrs at 232 °C) and evaluated using the method "O-Ring Molding and Compression Set" as described above. The results are shown in Table 4.

TABLE 1

1H -NMR analysis shows that VDF/TFE/P #2 (AFLAS 200P) contains an onium. The combined ID and 2D ¾-NMR spectral data were used to positively confirm the presence of a small amount of a component with a tetrabutylammonium cationic specie (0.36 wt.% of (CH ₃ CH ₂ CH ₂ CH ₂ ) ₄ -N ⁽⁺⁾ . TABLE 2

NT= not tested TABLE 3

NT= not tested

Table 4

NT= not tested

[00102] Foreseeable modifications and alterations of this invention will be apparent to those skilled in the art without departing from the scope and spirit of this invention. This invention should not be restricted to the embodiments that are set forth in this application for illustrative purposes.