Method for producing fluoroelastomers

Abstract

The present invention relates to a process for producing fluoroelastomers with iodinated / brominated chain ends, in particular vinylidene fluoride (VDF)-based fluoroelastomers, in emulsion polymerization, which does not require the addition of fluorosurfactants or hydrogenated surfactants, and to the fluoroelastomers obtainable from said process.

Description

[Technical Field]

[0001] Cross-reference of related patent applications This application claims priority to European Patent Application No. 20213775.8, filed on 14 December 2020, and the entire contents of this application are incorporated herein by reference for any purpose.

[0002] The present invention relates to a method for producing fluoroelastomers having iodized / brominated chain ends, particularly vinylidene fluoride (VDF)-based fluoroelastomers, in emulsion polymerization, wherein the method does not require the addition of a fluorosurfactant, and to the fluoroelastomers that can be obtained by this method. [Background technology]

[0003] Vulcanized (per)fluoroelastomers have several desirable properties, including heat resistance, chemical resistance, and weather resistance, and have therefore been used in a variety of applications, particularly in the manufacture of sealing articles such as oil seals, gaskets, shaft seals, and O-rings.

[0004] Methods frequently used to produce curable (per)fluoroelastomers, particularly (per)fluoroelastomers having iodine or bromine atoms at the polymer chain ends, include aqueous emulsion polymerization of one or more fluorinated monomers under chain transfer control using iodized or brominated (fluoro)(hydro)carbon compounds; such polymerization is generally carried out in the presence of a fluorinated surfactant necessary to ensure latex stability, enhance kinetics, and avoid reactor buildup or contamination.

[0005] For example, U.S. Patent Application No. 2007 / 0100062 (DuPont Performance Elastomers LLC) discloses fluoroelastomers having bromine and / or iodine-curable moieties prepared by emulsion polymerization. While it is widely disclosed that surfactants are optional components, all examples require the use of fluorinated surfactants (e.g., perfluorohexylethylsulfonic acid). More recently, due to the increasing problems associated with the use of fluorinated surfactants, reactions requiring non-fluorinated surfactants are disclosed in the art, for example, U.S. Patent Application No. 2018 / 0237628 and U.S. Patent Application No. 2018 / 0148527 (both in the name of AGC Inc.).

[0006] Currently, efforts are being made to phase out the use of fluorinated surfactants, and methods are being developed to produce (per)fluoropolymer products by aqueous polymerization procedures that do not require the addition of fluorinated surfactants, and in some cases, the process is carried out entirely in the absence of any surfactants. Stabilized latex without fluorosurfactants is generally achieved by adapting the conditions to produce polar end groups that can positively influence the chemical properties of the end groups, i.e., the stability of the latex.

[0007] As far as methods for producing fluoroelastomers are concerned, when the goal is to produce Br / I-containing fluororubber without the addition of surfactants, managing the delicate balance between the need for hydrocarbon surfactants (also called hydrocarbon emulsifiers) to have as many reactive chain ends as possible to have recognizable crosslinking ability and good sealing performance while ensuring latex stability is a challenging task.

[0008] On the other hand, Solvay Specialty Polymers Italy SpA's International Publication No. 2019 / 002180 (03.01.2019) describes a method for producing VDF-based fluoropolymers, particularly fluoroelastomers, in the presence of an organic radical initiator and a redox initiation system containing a sulfinic acid group, resulting in a polymer structure with fewer branches. According to this document, fluorosurfactants are commonly used, but paragraph

[0068] mentions the possibility of avoiding the use of fluorosurfactants. Further paragraph

[0040] states that the incorporation of iodine or bromine atoms into the fluoroelastomers obtained by this method can be achieved by the addition of iodination and / or brominated chain transfer agents during polymerization. All examples relate to embodiments, on the one hand, use is carried out with surfactants, and iodination or brominated chain ends are not used. [Overview of the project] [Means for solving the problem]

[0009] Herein, surprisingly, the applicant has found that the problem of providing an I / Br-terminated (per)fluoroelastomer with remarkable crosslinking ability and sealing performance, while offering an acceptable polymerization kinetics with no contamination / accumulation and good latex stability, can be solved by carrying out an emulsion polymerization process involving the reaction of at least one unsaturated fluorinated monomer with at least one organic peroxide and at least one compound having a sulfinic acid group in the presence of an I / Br chain transfer agent, under conditions where the amounts of the initiator system components and chain transfer agent are strictly limited while setting the precise ratio of the initiator system components and chain transfer agent.

[0010] Accordingly, in one embodiment, the present invention relates to a method for producing a (per)fluoroelastomer [fluoroelastomer (A)] comprising iodine chain termini and / or bromine chain termini, the method comprising, in the presence of a chain transfer agent [agent (CTA-X)] having an I atom and / or a Br atom (preferably an I atom), and in the presence of at least one composition [composition (CS)] comprising a redox initiation system [system (R)] comprising at least one organic radical initiator [initiator (O)] and at least one compound [compound (S)] having at least one sulfinic acid group, at least 1 / 2 of a (per)fluorinated monomer [monomer (M)] different from vinylidene fluoride (VDF). F This includes polymerizing VDF in the presence of ) Here, - The amount of initiator (O) is at least 1.50 mmol and a maximum of 15.00 mmol of O2 per 1 kg of fluoroelastomer (A); - The amount of compound (S) is at least 0.20 and at most 2.00 g per 1 kg of fluoroelastomer (A); and - The ratio of the drug (CTA-X) to the composition (CS) is at least 2.00 and a maximum of 8.00 g of composition (CS) per X / g, where X is the amount of I and / or Br in the drug (CTA-X); and This emulsion polymerization is carried out without the addition of any fluorinated surfactants or hydrogenation surfactants.

[0011] The applicant has surprisingly found that the method according to the present invention enables the production of a rational dynamic latex of an I / Br-containing (per)fluoroelastomer that has high Mooney viscosity (i.e., high molecular weight), remarkable curing behavior, good sealing properties, and colloidal stability in the aqueous phase, and as a result, no significant accumulation or contamination occurs in the reactor, and no undesirable coagulation phenomena occur.

[0012] Advantageously, the high molecular weight (per) fluoroelastomer latex of the present invention contains no added fluorosurfactants or hydrogenation surfactants, while limiting the amount of polar end groups of formula -CH2OH and limiting the amount of hydrogenation chain ends (such as formula -CF2H, -CF2CH3, -CH2CH3, and -C(CH3)3), while having a high proportion of halogenated chain ends.

[0013] Accordingly, in a second aspect, the present invention relates to an aqueous latex comprising particles of at least one fluoroelastomer (A) including iodine chain ends and / or bromine chain ends, i.e., (per)fluoroelastomer, wherein the fluoroelastomer (A) comprises VDF and at least one monomer (M) different from VDF. F The fluoroelastomer (A) contains repeating units derived from ), Having a Mooney viscosity (ML)(1+10) of at least 10 MU at -121°C; -Fluoroelastomer (A) containing -CH2OH chain termini in amounts less than -0 to 5 mmol / kg; --Contains hydrogen-containing chain ends selected from the group consisting of CF2H and -CF2CH3 in an amount of 0.01 to 10 mmol / kg of fluoroelastomer (A); - Containing I / Br containing chain ends of the formula -CH2-X (where X is I or Br, preferably I) in an amount of at least 65 mol% relative to the total moles of the chain ends, Here, the latex is produced by emulsion polymerization without the addition of any fluorinated surfactant or hydrogenation surfactant.

[0014] In a further embodiment, the present invention relates to a fluoroelastomer (A) containing iodine chain termini and / or bromine chain termini, i.e., a (per)fluoroelastomer, wherein the fluoroelastomer (A) is composed of VDF and at least one monomer different from VDF (M F The fluoroelastomer (A) contains repeating units derived from ), Having a Mooney viscosity (ML)(1+10) of at least 10 MU at -121°C; -Fluoroelastomer (A) containing -CH2OH chain termini in amounts less than -0 to 5 mmol / kg; --Contains hydrogen-containing chain ends selected from the group consisting of CF2H and -CF2CH3 in an amount of 0.01 to 10 mmol / kg of fluoroelastomer (A); - Containing I / Br containing chain ends of the formula -CH2-X (where X is I or Br, preferably I) in an amount of at least 65 mol% relative to the total moles of the chain ends, Here, the fluoroelastomer is produced by emulsion polymerization without the addition of any fluorinated surfactant or hydrogenation surfactant.

[0015] In a further embodiment, the present invention relates to the following: - At least one fluoroelastomer (A), i.e., a (per) fluoroelastomer containing iodine chain ends and / or bromine chain ends (the fluoroelastomer (A) is VDF, and at least one monomer different from VDF (M F The fluoroelastomer (A) includes repeating units derived from ), Having a Mooney viscosity (ML)(1+10) of at least 10 MU at -121°C; -Fluoroelastomer (A) containing -CH2OH chain termini in amounts less than -0 to 5 mmol / kg; --Contains hydrogen-containing chain ends selected from the group consisting of CF2H and -CF2CH3 in an amount of 0.01 to 10 mmol / kg of fluoroelastomer (A); - Containing I / Br containing chain ends of the formula -CH2-X (where X is I or Br, preferably I) in an amount of at least 65 mol% relative to the total moles of the chain ends, Here, the fluoroelastomer is produced by emulsion polymerization without the addition of any fluorinated surfactant or hydrogenation surfactant; and - At least one organic peroxide, This relates to a curable composition containing [a specific compound].

[0016] A method for producing a cured article, and a cured article obtained from the above-mentioned curable composition, are further objectives of the present invention. [Modes for carrying out the invention]

[0017] For the purposes of this specification and the following claims, For example, the use of parentheses around symbols or numbers that identify a formula, such as "fluoroelastomer (A)," is solely for the purpose of better distinguishing the symbols or numbers from the rest of the text, and therefore, such parentheses may be omitted; The expression "essentially consisting of" is intended, when used in conjunction with the repeating units of fluoroelastomer (A), to indicate that small amounts of terminal chains, defects, irregularities, and monomer rearrangements are permissible in fluoroelastomer (A), but their amounts are less than 5 mol%, more preferably less than 2 mol%, and even more preferably less than 1 mol%, based on the total number of moles of fluoroelastomer (A); - The terms "1,1-difluoroethylene," "1,1-difluoroethene," and "vinylidene fluoride" are used as synonyms and are referred to by the acronym "VDF"; - The term "fluoroelastomer" is intended to refer to an essentially amorphous polymer having, preferably a low degree of crystallinity (having a heat of fusion of less than 5 J / g, preferably less than 3 J / g, and more preferably less than 1 J / g, as measured by ASTM D-3418) and a glass transition temperature (Tg) below room temperature. Fluoroelastomers advantageously have a Tg of less than 10°C, preferably less than 5°C, and more preferably less than 0°C; - The term "fluorinated surfactant" is intended to refer to partially and fully fluorinated surfactants.

[0018] Suitable monomer (M F Non-restrictive examples of ) include, among others: (a) C2-C8 perfluoroolefins such as tetrafluoroethylene (TFE) and hexafluoropropylene (HFP); (b) Vinyl fluoride (VF), trifluoroethylene (TrFE), formula CH2=CH-R f (where R f is a C1-C6 perfluoroalkyl group) a hydrogen-containing C2-C8 olefin different from VDF, such as perfluoroalkyl ethylene; (c) C2-C8 chloro and / or bromo and / or iodo-fluoro olefins such as chlorotrifluoroethylene (CTFE); (d) formula CF2=CFOR f (where R f is a C1-C6 (per)fluoroalkyl group, for example -CF3, -C2F5, -C3F7) of (per)fluoroalkyl vinyl ether (PAVE); (e) formula CF2=CFOX (where X is a C1-C 12 [(per)fluoro]-oxyalkyl, for example, perfluoro-2-propoxypropyl group) of (per)fluoro-oxy-alkyl vinyl ether; (f) formula:

Chemical formula

[0019] The fluoroelastomer (A) is generally preferable to contain repeating units derived from HFP in addition to repeating units derived from VDF.

[0020] In this case, the fluoroelastomer (A) typically contains at least 10 mol%, preferably at least 12 mol%, and more preferably at least 15 mol%, of repeating units derived from HFP, relative to the total repeating units of the fluoroelastomer (A).

[0021] Furthermore, fluoroelastomer (A) typically contains up to 45 mol%, preferably up to 40 mol%, and more preferably up to 35 mol%, of repeating units derived from HFP, relative to the total repeating units of fluoroelastomer (A).

[0022] Fluoroelastomer (A) contains repeating units derived from VDF and HFP, in addition to the following: General formula: [ka] (In the formula, R1, R2, R3, R4, R5 and R6 are optionally halogenated C1-C5 groups, which may contain H, a halogen, or one or more oxygen groups; Z is a linear or branched C1-C5 group optionally containing an oxygen atom) 18 Repeating units derived from at least one bis-olefin [bis-olefin (OF)] having an optionally halogenated alkylene or cycloalkylene radical, or a (per)fluoropolyoxyalkylene radical; Repeating units derived from at least one (per)fluorinated monomer different from VDF and HFP; and Repeating units derived from at least one hydrogen-containing monomer It may include one or more of the following.

[0023] Examples of hydrogenation monomers include, among others, non-fluorinated alpha-olefins, such as ethylene, propylene, 1-butene, diene monomers, and styrene monomers, with alpha-olefins being typically used. C2-C8 non-fluorinated alpha-olefins (Ol), more specifically ethylene (E) and propylene (F), would be selected to achieve improved basic resistance.

[0024] The bis-olefin (OF) is preferably selected from the group consisting of those conforming to formulas (OF-1), (OF-2), and (OF-3): [ka] In the formula, j is an integer between 2 and 10, preferably between 4 and 8, and R1, R2, R3, R4 are equal to or different from each other, and are H, F, or C. 1~5 The preferred bis-olefin of type (OF-1) is alkyl or (per)fluoroalkyl; H2C=CH-(CF2)6-CH=CH2. [ka] During the ceremony, Each of A, which is equal to or different from each other and in each occurrence, is independently selected from F, Cl, and H; Each of B is equal to or different from each other and in each occurrence, F, Cl, H and OR B Selected independently from, where R B This may be a branched or linear alkyl chain that can be partially, substantially, or completely fluorinated or chlorinated; E is a divalent group having 2 to 10 carbon atoms, optionally fluorinated, and may have an ether bond inserted; preferably E is -(CF2) m -Based on (m is an integer between 3 and 5); A preferred bis-olefin of the (OF-2) type is F2C=CF-O-(CF2)5-O-CF=CF2. [ka] In the formula, E, A, and B have the same meanings as defined above; R5, R6, and R7, which are equal to or different from each other, are H, F, or C 1~5 It is an alkyl or (per)fluoroalkyl group.

[0025] When bis-olefins are used, the resulting fluoroelastomer (A) typically contains 0.01 mol% to 5 mol% of units derived from bis-olefins relative to the total amount of units of the fluoroelastomer (A).

[0026] Optionally, the fluoroelastomer (A) may include curing sites containing repeating units, i.e., units derived from monomers having curing sites.

[0027] Among the repeating units containing hardened areas, the following are particularly important: (CSM-1) formula: [ka] (In the formula, each A that is equal to or different from each other and each that appears Hf Each of these is independently selected from F, Cl, and H; B Hf F, Cl, H and OR Hf B (Here, R Hf B (These are either branched-chain or linear alkyl radicals that can be partially, substantially, or completely fluorinated or chlorinated; and each W is equal to or different from the others as it appears.) Hf Each of them is independently a covalent bond or an oxygen atom; EHf R is a divalent group having 2 to 10 carbon atoms that is optionally fluorinated; Hf R is a branched or linear alkyl radical that can be partially, substantially, or completely fluorinated; Hf is a halogen atom selected from the group consisting of iodine and bromine, which may have an ether bond inserted; preferably E is -(CF2) m -Iodine or bromine-containing monomers (where m is an integer between 3 and 5): (CSM-2) A cyanide group-containing ethylenically unsaturated compound that may be fluorinated. We can list some examples.

[0028] Among the monomers containing the curing site of type (CSM1), the preferred monomer is as follows: (CSM1-A) formula: [ka] Iodine-containing perfluorovinyl ethers (wherein m is an integer from 0 to 5, n is an integer from 0 to 3, provided that at least one of m and n is non-zero, and Rfi is F or CF3 (as described in particular in U.S. Patent No. 4,745,165 (AUSIMONT SPA), U.S. Patent No. 4,564,662 (MINNESOTA MINING), and European Patent Application Publication No. 199138A (DAIKIN IND., LTD.)) and (CSM-1B) formula: CX 1 X 2 =CX 3 -(CF2CF2) p -I (In the formula, X is equal to or different from each other.) 1 , X 2 and X 3 Each of these is independently either H or F; p is an integer between 1 and 5) an iodine-containing ethylenically unsaturated compound (among these compounds, we can list CH2=CHCF2CF2I, I(CF2CF2)2CH=CH2, ICF2CF2CF=CH2, and I(CF2CF2)2CF=CH2); (CSM-1C) formula: CHR=CH-Z-CH2CHR-I (In the formula, R is H or CH3, and Z is a linear or branched C1-C group optionally containing one or more ether oxygen atoms.) 18 Iodine-containing ethylenically unsaturated compounds (which are (per)fluoroalkyl radicals or (per)fluoropolyoxyalkylene radicals) (among these compounds, CH2=CH-(-F2)4CH2CH2I, CH2=CH-(CF2)6CH2CH2I, CH2=CH-(CF2)8CH2CH2I, and CH2=CH-(CF2)2CH2CH2I can be cited); (CSM-1D) Selected from the group consisting of bromo and / or iodoalphaolefins containing 2 to 10 carbon atoms, such as bromotrifluoroethylene or bromotetrafluorobutene as described in U.S. Patent No. 4035565 (DU PONT), or bromo and / or iodoalphaolefins of other compounds disclosed in U.S. Patent No. 4694045 (DU PONT).

[0029] Among the type (CSM2) curing site-containing monomers, the preferred monomers are as follows: (CSM2-A) Formula CF2=CF-(OCF2CFX CN ) m -O-(CF2) n -CN(X CN A perfluorovinyl ether containing a cyanide group (where m is 0, 1, 2, 3, or 4; n is an integer from 1 to 12); (CSM2-B) Formula CF2=CF-(OCF2CFX CN ) m’ -O-CF2-CF(CF3)-CN(X CN It is selected from the group consisting of perfluorovinyl ethers that have a cyanide group (where m' is 0, 1, 2, 3, or 4), and is F or CF3.

[0030] Specific examples of type CSM2-A and CSM2-B curing site-containing monomers suitable for the purposes of the present invention are described in particular in U.S. Patent No. 4,281,092 (DU PONT), U.S. Patent No. 5,447,993 (DU PONT), and U.S. Patent No. 5,789,489 (DU PONT).

[0031] Nevertheless, it is generally preferable that the fluoroelastomer (A) does not contain repeating units derived from the monomers containing the curing site.

[0032] Preferred fluoroelastomer (A) is the following composition (in mole percent): (i) 35-85% vinylidene fluoride (VDF), 10-45% hexafluoropropene (HFP), 0-30% tetrafluoroethylene (TFE), 0-15% perfluoroalkyl vinyl ether (PAVE), 0-5% bis-olefin (OF); (ii) 50-80% vinylidene fluoride (VDF), 5-50% perfluoroalkyl vinyl ether (PAVE), 0-20% tetrafluoroethylene (TFE), 0-5% bis-olefin (OF); (iii) 20-30% vinylidene fluoride (VDF), 10-30% C2-C8 non-fluorinated olefin (Ol) (especially E or P), 18-27% hexafluoropropene (HFP) and / or perfluoroalkyl vinyl ether (PAVE), 10-30% tetrafluoroethylene (TFE), 0-5% bis-olefin (OF); 50-80% tetrafluoroethylene (TFE), 20-50% perfluoroalkyl vinyl ether (PAVE), 0-5% bis-olefin (OF); (iv) Tetrafluoroethylene (TFE) 45-65%, C2-C8 non-fluorinated olefins (Ol) 20-55%, vinylidene fluoride 0-30%, bis-olefins (OF) 0-5%; (v) Tetrafluoroethylene (TFE) 32-60% mol%, C2-C8 non-fluorinated olefin (Ol) 10-40%, perfluoroalkyl vinyl ether (PAVE) 20-40%, fluorovinyl ether (MOVE) 0-30%, bis-olefin (OF) 0-5%; (vi) Tetrafluoroethylene (TFE) 33-75%, perfluoroalkyl vinyl ether (PAVE) 15-45%, vinylidene fluoride (VDF) 5-30%, hexafluoropropene HFP 0-30%, bis-olefin (OF) 0-5%; (vii) 35-85% vinylidene fluoride (VDF), 5-40% fluorovinyl ether (MOVE), 0-30% perfluoroalkyl vinyl ether (PAVE), 0-40% tetrafluoroethylene (TFE), 0-30% hexafluoropropene (HFP), 0-5% bis-olefin (OF); (viii) Tetrafluoroethylene (TFE) 20-70%, Fluorovinyl ether (MOVE) 30-80%, Perfluoroalkyl vinyl ether (PAVE) 0-50%, Bis-olefin (OF) 0-5%, It possesses the following characteristics.

[0033] A more preferred fluoroelastomer (A) contains 35-85% vinylidene fluoride (VDF), 10-45% hexafluoropropene (HFP), 0-30% tetrafluoroethylene (TFE), 0-15% perfluoroalkyl vinyl ether (PAVE), and 0-5% bis-olefin (OF).

[0034] In fact, as described above, fluoroelastomer (A) has iodine chain ends and / or bromine chain ends, and therefore already provides effective curing sites for crosslinking.

[0035] As described above, the I atom and / or Br atom constitute fluoroelastomer (A) as terminal groups of the fluoroelastomer (A) chain. As explained, this is obtained in the method of the present invention by adding at least one iodizing / brominating chain transfer agent [agent (CTA-X)] to the polymerization medium during the production of the fluoroelastomer. The agent (CTA-X) is preferably the following: Iodinating and / or brominating organic chain transfer agents (preferred organic chain transfer agents are typically those of formula R f (I) x (Br) y (In the formula, R f (wherein x and y are integers between 0 and 2 such that 1 ≤ x + y ≤ 2, and x is a (per)fluoroalkyl or (per)fluorochloroalkyl containing 1 to 8 carbon atoms); and In particular, selected from the group consisting of alkali metal or alkaline earth metal iodides and / or bromides, such as those described in U.S. Patent No. 5,173,553 (AUSIMONT SRL.).

[0036] This means that the preferred agent (CTA-X) is an iodinating and / or brominating organic chain transfer agent, more preferably of formula R f (I) x (Br) y (In the formula, R f However, it is a (per)fluoroalkyl or a (per)fluorochloroalkyl containing 1 to 8 carbon atoms, while x and y are integers from 0 to 2 such that 1 ≤ x + y ≤ 2. Most preferably, formula R' f (I) x’ (Br) y’ (In the formula, R' f However, it is a perfluoroalkyl group containing 1 to 8 carbon atoms, while x' and y' are integers between 0 and 2 such that 1 ≤ x' + y' ≤ 2, and most preferably x' = 2 and y' = 0.

[0037] In the method of the present invention, an iodized drug (CTA-X), particularly formula R f (I)2 or R' f (I)2 is preferred, in the formula R f and R' f The above is true.

[0038] As described above, the ratio of the agent (CTA-X) to the composition (CS) in the method of the present invention is at least 2.00 and up to 8.00 g of composition (CS) in X / g, where X is the amount of I and / or Br in the agent (CTA-X). The applicant has found that careful control of this weight ratio is essential to ensure the production of radicals and chain ends in the targeted fluoroelastomer (A), for example, to provide remarkable colloidal stability and reactivity in crosslinking, thereby resulting in cured articles having remarkable sealing performance.

[0039] Such a weight ratio of halogens between the drug (CTA-X) and composition (CS) is preferably X / g of composition (CS), which is at least 2.50, more preferably at least 3.20, even more preferably at least 3.40, and up to 7.60, preferably up to 7.50, and more preferably up to 7.00 g, where X is the amount of I and / or Br in the drug (CTA-X).

[0040] Since the drug (CTA-X) is preferably an iodation chain transfer agent, the amounts of (CTA-X) and composition (CS) are such that the iodine / composition (CS) ratio is at least 2.00, preferably at least 2.50, preferably at least 3.00, more preferably at least 3.20, even more preferably at least 3.40 and at most 7.60, preferably at most 7.50, and more preferably at most 7.00 g of composition (CS) I / g.

[0041] As described above, the method of the present invention comprises a redox initiation system [system (R)] comprising at least one organic radical initiator [initiator (O)] and at least one composition [composition (CS)] comprising at least one compound [compound (S)] having at least one sulfinic acid group, and optionally in the presence of further components, VDF and at least one monomer (M) F This includes polymerizing ).

[0042] Any initiator (O) known to initiate the polymerization of vinylidene fluoride can be used. Among them, the following can be listed: (a) Azo compounds such as 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile); tert-butylazo-2-cyanobutane, 2,2'-azobis(isobutyronitrile); (b) Diacyl peroxides such as diacetyl peroxide, disuccinate peroxide, dipropionyl peroxide, dibutyryl peroxide, dibenzoyl peroxide, and dilauroyl peroxide; benzoylacetyl peroxide and diglutarate peroxide; (c) In particular di-tert-butyl peroxide (DTBP), t-butylcumyl peroxide; 2,5-dimethyl-2,5-di(t-butylperoxy)hexane; dicumyl peroxide; 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane; dialkyl peroxides, including di-tert-amyl peroxide; (d) Hydroperoxides, particularly t-butyl hydroperoxide (TBHP), cumene hydroperoxide, and tertiary amyl hydroperoxide; (e) Peracid esters and salts thereof, such as ammonium, sodium, or potassium salts. An example of a peracid is peracetic acid. Esters of peracids can also be used in the same way, and examples include: tert-butylperoxybenzoate, tert-butylperoxyacetate, and tert-butylperoxypivalate; (f) Peroxy dicarbonates, particularly diisopropyl peroxydicarbonate, tert-butyl-peroxyisopropyl carbonate; di-n-propyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, di-n-butyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, dimyristil peroxydicarbonate, dicetyl peroxydicarbonate, diethyl peroxydicarbonate, peroxydicarbonate, These are some examples.

[0043] The initiator (O) is preferably selected from among organic peroxides, particularly from those listed in (b) to (f) above.

[0044] As described above, in the method of the present invention, the amount of initiator (O) is at least 1.50 mmol and a maximum of 15.00 mmol of O2 per 1 kg of fluoroelastomer (A).

[0045] Such an amount is expressed as millimoles of the -OO- (peroxide) portion in the initiator (O), and represents the amount of reactive oxygen species that contribute to the generation of radical species.

[0046] For any initiator (O) that does not contain any peroxide moiety, the millimoles of the -OO-(peroxide) moiety in the initiator (O) can be equally determined based on the decomposition mechanism that leads to the generation of radical species; organoazo groups are particularly known to decompose by removing nitrogen and producing two radical species, and are therefore equivalent to the -OO-(peroxide) moiety in terms of radical species generation.

[0047] Preferably, the initiator (O) is used in the method of the present invention in an amount of O2 of up to 15.00, more preferably up to 12.00 mmol, and even more preferably up to 10.00 mmol per 1 kg of fluoroelastomer (A); and / or in an amount of O2 of preferably at least 1.80, more preferably at least 2.00, and even more preferably at least 2.50 mmol per 1 kg of fluoroelastomer (A).

[0048] When using an initiator (O) in combination with composition (CS), as described above, it is essential to use the initiator (O) in an amount of O2 up to 15.00 mmol per kg of fluoroelastomer (A) in order to enable sufficient production of radicals, and therefore polar chain ends, through the action of the materially important components of composition (CS) for achieving latex colloidal stability during polymerization.

[0049] On the other hand, when combined with composition (CS), at least 1.50 mmol of initiator (O) per kg of fluoroelastomer (A) is required to achieve an acceptable polymerization rate, thanks to the synergistic effect of composition (CS).

[0050] It was also found that the best results were found when the molar ratio of the halogen content of (CTA-X) to the peroxide content of the initiator (O) was at least 3.00, preferably at least 3.50, more preferably at least 4.00, and / or up to 15.00, preferably up to 13.00, and more preferably up to 12.00, for X / mol O2.

[0051] Such a molar ratio of the drug (CTA-X) to the initiator (O) is expressed as moles of X / moles of O2, where moles of X are the molar amounts of I and / or Br in the drug (CTA-X) and moles of O2 are the molar amounts of the peroxidized moiety (-OO-) in the initiator (O). The applicant has found that careful control of this weight ratio is essential to ensure the production of radicals and chain ends in the targeted fluoroelastomer (A), for example, to provide remarkable colloidal stability and reactivity in crosslinking, thereby resulting in cured articles having remarkable sealing properties.

[0052] Thus, in the method of the present invention, VDF and at least one monomer (M FPolymerization with ) is carried out in the presence of at least one composition [composition (CS)] comprising at least one compound [composition (S)] having at least one sulfinic acid group.

[0053] Compound (S) is an organic compound having the sulfinic acid group bonded to a carbon atom.

[0054] The expression "possessing at least one sulfinic acid group" means, in this specification, that the compound (S) has an acidic form, i.e., a -S(O)-OH group, or a chloride form, i.e., a -S(O)-O-[ m [Y a m+ ] Used to mean that the sulfinic acid group may be included as a sulfinic salt group, where Y a is an m-valence cation, where m is an integer.

[0055] Generally, compound (S) contains the sulfinic acid group in the form of a sulfinic salt group, as described above.

[0056] Preferably, the compound (S) is of the following formula (SI): [ka] (In the formula, M is a hydrogen atom, an ammonium ion, or a monovalent metal ion; R 20 is -OH or -N(R 4 )(R 5 ) and here, R is either identical or different to each other. 4 and R 5 Each of these is a linear or branched alkyl chain having a hydrogen atom or 1 to 6 carbon atoms; R 21 This is a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, a 5-membered or 6-membered cycloalkyl group, or a 5- or 6-membered aryl group; R 22is -COOM, -SO3M, -C(=O)R 4 , -C(=O)N(R 4 )(R 5 ), -C(=O)OR 4 , where M, R 4 and R 5 are as defined above), and salts thereof having at least one monovalent metal ion.

[0057] Preferably, M is a hydrogen atom or a monovalent metal ion.

[0058] Preferably, the monovalent metal ion is selected from sodium and potassium.

[0059] Preferably, R 20 is selected from a hydroxyl group or an amino group.

[0060] Preferably, R 21 is selected from a hydrogen atom, a linear or branched alkyl group having from 1 to 3 carbon atoms, and a 5- or 6-membered aryl group.

[0061] Preferably, R 22 is selected from -COOM, -SO3M, and C(=O)OR 4 , where M, R 4 and R 5 are as defined above.

[0062] Preferred compound(s) conform to the above formula (S-I) (where M is sodium, R 20 is -OH, R 21 is a hydrogen atom, R 22 is selected from -COOM, -SO3M, and C(=O)OR 4 , where M, R 4 and R 5 are as defined above).

[0063] More preferred compound(s) conform to the above formula (S-I) (where M is sodium, R 20is -OH, and R 21 R is a hydrogen atom, 22 This follows the rule that M is sodium, and -COOM is true.

[0064] Preferably, the composition (CS) contains a compound according to formula (SI) as defined above, in an amount of at least 10% by weight, preferably at least 20% by weight, and more preferably at least 25% by weight, based on the total weight of the composition (CS).

[0065] Preferably, the composition (CS) contains a compound according to formula (SI) as defined above, in an amount of up to 50% by weight, preferably up to 45% by weight, and more preferably at least 40% by weight, based on the total weight of the composition (CS).

[0066] Preferably, the composition (CS) further comprises a compound [compound (S3)] containing at least one sulfonic acid group.

[0067] The expression "possessing at least one sulfonic acid group" means, in this specification, that compound (S) has an acidic form, i.e., a -S(O)2-OH group, or a chloride form, i.e., a -S(O)2-O-[ m [Y a m+ ] Used to mean that the sulfonic acid group may be included as a sulfonic salt group, where Y a is an m-valence cation, where m is an integer.

[0068] Generally, compound (S) contains the sulfonic acid group in the form of a sulfonic salt group, as described above.

[0069] Preferably, the compound (S3) is given by the following formula (S3-I): [ka] (In the formula, M, R 20 , R 21 and R 22This has the same meaning as defined above for compounds of formula (SI); in particular, M is a monovalent metal ion.

[0070] Preferably, the composition (CS) contains a compound according to formula (S3-I) as defined above, in an amount of at least 5% by weight, preferably at least 10% by weight, and more preferably at least 15% by weight, based on the total weight of the composition (CS).

[0071] Preferably, the composition (CS) contains a compound according to formula (S3-I) as defined above, in an amount of up to 50% by weight, preferably up to 45% by weight, and more preferably up to 40% by weight, based on the total weight of the composition (CS).

[0072] According to a particular embodiment, the composition (CS) further comprises a sulfite or a salt thereof (also referred to as "sulfite"), i.e., a compound of the formula MO-S(O)-OM, where each of M is equal to or different from one another, and independent as described above, and M is preferably H and / or Na, in particular in sodium sulfite and sodium bisulfite, etc.

[0073] Preferably, the composition (CS) contains at least 1% by weight, preferably at least 3% by weight, and more preferably at least 5% by weight of the sulfite or its salt, based on the total weight of the composition (CS).

[0074] Preferably, the composition (CS) contains up to 40% by weight, preferably up to 30% by weight, and more preferably up to 25% by weight of the sulfite or its salt, based on the total weight of the composition (CS).

[0075] According to a particular embodiment, the composition (CS) further comprises sulfuric acid or a salt thereof (also referred to as "sulfate"), i.e., a compound of the formula MO-S(O)2-OM, where each of M is equal to or different from one another, and independent as described above, and M is preferably H and / or Na, in particular in sodium sulfate and sodium bisulfate, etc.

[0076] Preferably, the composition (CS) contains at least 5% by weight, preferably at least 8% by weight, and more preferably at least 10% by weight of the sulfite or its salt, based on the total weight of the composition (CS).

[0077] Preferably, the composition (CS) contains up to 40% by weight, preferably up to 30% by weight, and more preferably up to 25% by weight of the sulfite or its salt, based on the total weight of the composition (CS).

[0078] According to a preferred embodiment, composition (CS) is essentially a mixture comprising at least one compound (S) of formula (SI), at least one compound (S) of formula (S3-I), at least one sulfite, and at least one sulfate.

[0079] When used in relation to the components constituting the composition (CS), the expression "essentially consisting of ~" means that further small amounts (less than 1% by weight) of other compounds may be present as by-products or impurities without affecting the effectiveness of the composition (CS) in the method of the present invention.

[0080] According to a preferred embodiment, composition (CS) is as follows: -10 to 50% by weight, preferably 20 to 45% by weight, more preferably 25 to 40% by weight, of at least one compound (S) of formula (SI); -5 to 50% by weight, preferably 10 to 45% by weight, more preferably 15 to 40% by weight, of at least one compound (S) of formula (S3-I); -1 to 40% by weight, preferably 3 to 30% by weight, more preferably 5 to 25% by weight, of at least one sulfite; -5 to 40% by weight, preferably 8 to 30% by weight, more preferably 10 to 25% by weight, of at least one sulfate; A mixture consisting of the following, where weight % is based on the total weight of composition (CS).

[0081] A preferred example of the composition (CS) is commercially available from the BRUEGGEMANN-GROUP under the trade name Bruggolite®. In particular, the mixture marketed as Bruggolite® E28 has been found to be especially useful within the scope of the present invention.

[0082] Thus, in the method of the present invention, the emulsion polymerization is carried out without the addition of any fluorinated surfactant or hydrogenation surfactant.

[0083] In particular, emulsion polymerization is performed using the following formula: R * -X B- (T + ) (In the formula, R * This contains one or more etheric oxygen atoms, C5-C 16 (Per)fluoroalkyl chain or (Per)fluoropolyoxyalkylene chain, X B- -COO - or -SO3 - And, T + H + NH4 + (Selected from alkali metal ions) This is carried out without adding any fluorinated surfactants, in accordance with the following procedure.

[0084] Exemplary embodiments of fluorinated surfactants not added in the methods of the present invention include, among others: ammonium perfluorooctanoate; (per)fluoropolyoxyalkylenes terminated with one or more carboxylic acid groups, optionally chlorinated with sodium, ammonium and alkali metals, more preferably chlorinated with sodium; and partially fluorinated alkyl sulfonates.

[0085] Exemplary embodiments of hydrogenation surfactants not added in the method of the present invention include, in particular, sodium lauryl sulfate and sodium dodecylbenzenesulfonate.

[0086] Advantageously, the method of the present invention involves adding at least one further monomer (M) as defined above to an aqueous emulsion in the presence of the system (R) as defined above and optionally further components. F This includes polymerizing ) and VDF.

[0087] The method according to the present invention can preferably be carried out continuously, or in a semi-batch or batch manner.

[0088] The method of the present invention is carried out at a temperature selectable by those skilled in the art, particularly based on organic peroxides. Preferably, the method of the present invention is carried out at a temperature of 40°C to 120°C, more preferably 50°C to 100°C.

[0089] The method of the present invention is preferably carried out at a pressure of 10 to 60 bar, more preferably 25 to 55 bar.

[0090] As described above, another object of the present invention is an aqueous latex comprising at least one particle of fluoroelastomer (A) which may conform to all the features listed above for fluoroelastomer (A), as detailed above, wherein fluoroelastomer (A) is Having a Mooney viscosity (ML)(1+10) of at least 10 MU at -121°C; -Fluoroelastomer (A) containing -CH2OH chain termini in amounts less than -0 to 5 mmol / kg; --Contains hydrogen-containing chain ends selected from the group consisting of CF2H and -CF2CH3 in an amount of 0.01 to 10 mmol / kg of fluoroelastomer (A); - Containing I / Br containing chain ends of the formula -CH2-X (where X is I or Br, preferably I) in an amount of at least 65 mol% relative to the total moles of the chain ends, Here, the latex is produced by emulsion polymerization without the addition of any fluorinated surfactant or hydrogenation surfactant.

[0091] While not bound by this theory, the applicant argues that although the measured amount of -CH2OH chain ends may be below the detection limit of the technique used for its determination (see Experiments section), the non-zero concentration of -CH2OH chain ends is an inevitable consequence of using an initiator system that combines an initiator (O) and a composition (CS) containing compound (S), which is generally understood to enable achieving sufficient colloidal stability during polymerization and thus avoid phenomena such as contamination, reactor buildup, or premature solidification during the latex production of fluoroelastomers (A).

[0092] The amount of -CH2OH chain ends below the detection limit (0.05 mmol / Kg of fluoroelastomer (A)) is determined in certain preferred embodiments of the present invention; the total colloidal system provided by the components used in the method for producing the fluoroelastomer (A) is thought to have a positive effect on the ability of particles of such fluoroelastomer (A) having a limited number of polar chain ends to possess colloidal stability.

[0093] Another important attribute of fluoroelastomer (A) is the fact that it contains hydrogen-containing chain ends selected from the group consisting of -CF2H and -CF2CH3, which is a typical feature of the use of organic initiators used in their production methods. Nevertheless, the amount of such chain ends is limited in that it does not affect latex stability (related to -CH2OH chain ends) or crosslinking ability and crosslinking density (related to -CH2-X chain ends). Generally, the total amount of chain ends of the formula -CF2H and -CF2CH3 is less than 8 mmol / kg, preferably less than 5 mmol / kg, and more preferably less than 3 mmol / kg.

[0094] Fluoroelastomer (A) contains I / Br-containing chain ends of formula -CH2-X (where X is I or Br, preferably I) in an amount of at least 65 mol%, preferably at least 68 mol%, and more preferably at least 70 mol%, relative to the total moles of chain ends. In particular, fluoroelastomer (A) contains I-containing chain ends of formula -CH2-I in an amount of at least 65 mol%, preferably at least 68 mol%, and more preferably at least 70 mol%, relative to the total moles of chain ends.

[0095] Such terminal groups are not only important for ensuring suitable reactivity in crosslinking and achieving appropriate crosslink density, but they can also contribute to the colloidal stability necessary to maintain emulsion polymerization without the addition of fluorinated surfactants.

[0096] Thus, fluoroelastomer (A), as determined according to ASTM D1646, has a Mooney viscosity (ML)(1+10) of at least 10, preferably at least 15, more preferably at least 20 Mooney units (MU) at 121°C; and / or a Mooney viscosity (ML)(1+10) of up to 80 MU, preferably up to 75 MU, more preferably up to 70 MU at 121°C. In other words, fluoroelastomer (A) is a high molecular weight polymer and not a molecular weight-limited fluorowax or fluororubber. In fact, this is an important characteristic, and techniques for producing fluorubber without the addition of fluorosurfactants may not provide access to such high molecular weight materials.

[0097] In a further embodiment, the present invention relates to a fluoroelastomer (A) containing iodine chain termini and / or bromine chain termini, i.e., a (per)fluoroelastomer, wherein the fluoroelastomer (A) is composed of VDF and at least one monomer different from VDF (M F The fluoroelastomer (A) contains repeating units derived from ), Having a Mooney viscosity (ML)(1+10) of at least 10 MU at -121°C; -Fluoroelastomer (A) containing -CH2OH chain termini in amounts less than -0 to 5 mmol / kg; --Contains hydrogen-containing chain ends selected from the group consisting of CF2H and -CF2CH3 in an amount of 0.01 to 10 mmol / kg of fluoroelastomer (A); - Containing I / Br containing chain ends of the formula -CH2-X (where X is I or Br, preferably I) in an amount of at least 65 mol% relative to the total moles of the chain ends, Here, the fluoroelastomer is produced by emulsion polymerization without the addition of any fluorinated surfactant or hydrogenation surfactant.

[0098] Such fluoroelastomers (A) are advantageously obtained by solidifying them according to standard techniques for latex containing particles of fluoroelastomers (A), as described above.

[0099] When such fluoroelastomer (A) is formulated by adding the following curing components, 30 phr of C-black N990 MT; 4.00 phr of triallyl isocyanurate; 5.00 phr of ZnO and 3.00 phr of 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane may be added as follows: -M L= Minimum torque (lb × in) and M H= While the maximum torque (lb × in) is greater than 20 lb.in, preferably greater than 23 lb.in, and more preferably greater than 25 lb.in, when determined by MDR at 160°C according to ASTM D 5289, the M H -M L The difference; - For O-ring test specimens of standard AS568A type 214, when determined at 200°C for 70 hours according to ASTM D 395, method B, the compression set (C-SET) is less than 30, preferably less than 28, more preferably less than 25. It is something that has the following characteristics.

[0100] In a further embodiment, the present invention relates to the following: - At least one fluoroelastomer (A), i.e., a (per) fluoroelastomer containing iodine chain ends and / or bromine chain ends (the fluoroelastomer (A) is VDF, and at least one monomer different from VDF (M F The fluoroelastomer (A) contains repeating units derived from ), and the fluoroelastomer (A) is as follows: Having a Mooney viscosity (ML)(1+10) of at least 10 MU at -121°C; -Fluoroelastomer (A) containing -CH2OH chain termini in amounts less than -0 to 5 mmol / kg; --Contains hydrogen-containing chain ends selected from the group consisting of CF2H and -CF2CH3 in an amount of 0.01 to 10 mmol / kg of fluoroelastomer (A); - Containing I / Br containing chain ends of the formula -CH2-X (where X is I or Br, preferably I) in an amount of at least 65 mol% relative to the total moles of the chain ends, Here, the fluoroelastomer is produced by emulsion polymerization without the addition of any fluorinated surfactant or hydrogenation surfactant; and - At least one organic peroxide, This relates to a curable composition containing [a specific compound].

[0101] The organic peroxide is selected from those capable of producing radicals under curing conditions.

[0102] Commonly used organic peroxides include dialkyl peroxides (e.g., di-terbutyl peroxide and 2,5-dimethyl-2,5-di(terbutylperoxy)hexane); dicumyl peroxide; dibenzoyl peroxide; diterbutyl perbenzoate; and di[1,3-dimethyl-3-(terbutylperoxy)butyl] carbonate.

[0103] The curable composition of the present invention may further comprise the following: (a) A curing agent in an amount generally in the range of 0.5 to 10 phr, preferably 1 to 7 phr, relative to the fluoroelastomer (A); among those commonly used are triallyl cyanurate; triallyl isocyanurate (TAIC); tris(diallylamine)-s-triazine; triallyl phosphite; N,N-diallyl acrylamide; N,N,N',N'-tetraallyl malonamide; trivinyl isocyanurate; 2,4,6-trivinyl methyltrisiloxane; N,N'-bisallyl bicyclo-octa-7-en-disuccinimide (BOSA); the above bis-olefins (OF), particularly those of the formula CH2=CH-(CF2) n -CH=CH2 bisolefins, where triazine has the general formula: [ka] A curing aid having (wherein X may independently be hydrogen, chlorine, fluorine C1-C3 alkyl, or perfluoroalkyl; n is an integer in the range of 2-20, preferably 4-12, more preferably 4-8). TAIC is particularly preferred as a curing aid; (b) A metal compound in an amount in the range of 1 to 15 phr or 2 to 10 phr relative to fluoroelastomer (A), selected for example from oxides or hydroxides of divalent metals such as Mg, Zn, Ca, or Pb, and optionally bonded to a weak salt such as Ba, Na, K, Pb, Ca stearate, benzoate, carbonate, oxalate, or phosphate; (c) Other conventional additives such as thickeners, pigments, antioxidants, reinforcing agents (e.g., carbon black), and stabilizers.

[0104] A method for producing a cured article, and a cured article obtained from the above-mentioned curable composition, are further objectives of the present invention.

[0105] The cured articles can be selected from, in particular, pipes, joints, O-rings, hoses, and the like.

[0106] In a further embodiment, the present invention relates to a method for producing a cured article, comprising processing and curing a curable composition comprising at least one fluoroelastomer (A) and at least one organic peroxide.

[0107] The curable composition containing fluoroelastomer (A) can be secondarily processed into desired molded products, for example, by molding (injection molding, extrusion molding), calendering, or extrusion. The cured articles may be vulcanized (or cured) during the processing itself and / or in subsequent processes (post-treatment or post-curing).

[0108] If any disclosure of patents, patent applications, and published materials incorporated herein by reference conflicts with any description of this application to such an extent that it could obscure any term, the description herein shall prevail.

[0109] If any disclosure in any patent, patent application, or publication incorporated herein by reference is inconsistent with the description in this application to such an extent that it obscures the terminology, the description in this application shall prevail.

[0110] The present invention will be described in more detail below in relation to the following embodiments, but the purpose is merely illustrative and not to limit the scope of the invention. [Examples]

[0111] Experiment Section material: The following compounds: [ka] Bruggolite® Type E28, a mixture primarily composed of [substance name], was obtained from Bruggemann® and used as is.

[0112] Mooney viscosity: The Mooney viscosity (ML)(1+10) at 121°C was measured in accordance with ASTM D1646.

[0113] Determination of terminal groups The terminal groups were identified and quantified by NMR and / or infrared spectroscopy according to the method described in PIANCA, M., et al. J. Fluor. Chem. 1999, p. 95-71. In the table below, the condition "nd" is used to mean "undetectable" in relation to chain ends present at concentrations below the detection limit, i.e., less than 0.05 mmol / Kg.

[0114] Comparative Example 1 The demineralized water was introduced into a 5 L vertical autoclave equipped with a stirrer operating at 630 rpm after being discharged from the 5 L autoclave. The autoclave was then heated to 60°C and maintained at that temperature for the entire duration of the reaction. The autoclave pressure was increased by 12 bar by supplying HFP monomers. A gaseous mixture of the following monomers was supplied to the autoclave to bring the pressure to 26 bar: vinylidene fluoride (VDF) 48.5 mol%, hexafluoropropene (HFP) 26.5 mol%, and tetrafluoroethylene (TFE) 25 mol%. Subsequently, 3.42 g of C4F8I2 and 0.23 g of the bis-olefin of the formula H2C=CH-(CF2)6-CH=CH2 were introduced. A 29.4 g / L solution of t-butyl hydroperoxide (TBHP) in the demineralized water was pumped into the autoclave at a constant nominal supply rate. Simultaneously, but separately, a 62 g / L solution of Bruggolite® type E28 in desalinated water was pumped into the autoclave at essentially the same feed rate as TBHP. After initiation, the VDF / HFP / TFE mixture was continuously fed to maintain a constant pressure, and a total of 3.77 g of bis-olefins was added in 19 stages as described above. 5.14 g of C4F8I2 was added at a monomer conversion rate of 240 g. A final aliquot of 2.85 g of C4F8I2 was introduced at a monomer conversion rate of 960 g.

[0115] Polymerization was continued until a total monomer consumption of 1200 g was reached after 83 minutes; during such reaction time, detailed solutions of E28 and THBP, as detailed above, were supplied in 80 mL and 78 mL, respectively, and the autoclave was then reduced in pressure, ventilated, and cooled. The resulting latex had a solids content of 27.6 wt%. After coagulation with a solution of Al2(SO4)3 and drying, fluoroelastomer crumbs (1159 g) with a Mooney viscosity (ML) (1+10) of 21 MU were collected at 121 °C.

[0116] Comparative Example 2 The initial loading amounts of C4F8I2 and the bis-olefin of formula H2C=CH-(CF2)6-CH=CH2 were 2.86 g and 0.23 g, respectively, and the procedure was the same as in Example 1C, except that a continuous, constant feed of a 14.7 g / L solution of TBHP in desalinated water was pumped into the autoclave together with a continuous, separate, constant, essentially similar feed of a 31 g / L solution of Bruggolite® type E28 in desalinated water. After initiation, a VDF / HFP / TFE mixture was continuously fed to maintain a constant pressure, and a total of 3.77 g of bis-olefin was added in 19 stages. 4.08 g of C4F8I2 was added at a monomer conversion rate of 240 g. A final aliquot of 2.45 g of C4F8I2 was introduced at a monomer conversion rate of 960 g.

[0117] Polymerization was continued until a total monomer consumption of 1200 g was reached after 160 minutes; during such reaction time, 128 mL and 137 mL of detailed solutions of E28 and THBP, as detailed above, were supplied, respectively, and the autoclave was then reduced in pressure, aerated, and cooled. The resulting latex had a solids content of 27.6 wt%. After coagulation with Al2(SO4)3 solution and drying (1158 g), the Mooney viscosity (ML) (1+10) of the resulting fluoroelastomer aggregates was measured at 121°C at 25 MU.

[0118] Comparative Example 3 The procedure was the same as in Example 2C, except that the initial HFP pressure was 13 bar, and the VDF / HFP / TFE mixture was 26 bar, and the initial loading of C4F8I2 and the bis-olefin of formula H2C=CH-(CF2)6-CH=CH2 was also as in Example 2C. The continuous constant supply of an 8.4 g / L solution of TBHP in desalinated water was accompanied by a continuous, separate, constant, and essentially similar supply of a 17 g / L solution of Bruggolite® type E28 in desalinated water. After initiation, the VDF / HFP / TFE mixture was continuously supplied to maintain a constant pressure, and a total of 3.77 g of bis-olefin was added in 19 steps. 4.08 g of C4F8I2 was added at a monomer conversion rate of 240 g. A final aliquot of 2.45 g of C4F8I2 was introduced at a monomer conversion rate of 960 g.

[0119] Polymerization was continued until a total monomer consumption of 1200 g was reached after 187 minutes; during such reaction time, 160 mL and 171 mL of detailed solutions of E28 and THBP described above were supplied, respectively, and the autoclave was then reduced in pressure, aerated, and cooled. The resulting latex had a solids content of 24.5 wt%. After coagulation with Al2(SO4)3 solution and drying (1027 g), the Mooney viscosity (ML) (1+10) of the resulting fluoroelastomer aggregates was measured at 121°C at 29 MU.

[0120] Example 4 (According to the present invention) The procedure was the same as in Example 1, except that the initial HFP pressure was 12.5 bar, and similarly, 26 bar for the VDF / HFP / TFE mixture, and the initial packing was carried out with C4F8I2 (2.45 g) and bis-olefin of formula H2C=CH-(CF2)6-CH=CH2 (0.23 g). The continuous constant supply of a 2.8 g / L solution of TBHP in the demineralized water was accompanied by a continuous, separate, constant, and essentially similar supply of an 8 g / L solution of Bruggolite® type E28 in the demineralized water.

[0121] After initiation, a VDF / HFP / TFE mixture was continuously supplied to maintain a constant pressure, and a total of 3.77 g of bis-olefin was added in 20 steps. 3.67 g of C4F8I2 was added at a monomer conversion rate of 240 g. A final aliquot of 2.04 g of C4F8I2 was introduced at a monomer conversion rate of 960 g.

[0122] Polymerization was continued until a total monomer consumption of 1200 g was reached after 171 minutes; during such reaction time, 154 mL and 158 mL of detailed solutions of E28 and THBP described above were supplied, respectively, and the autoclave was then reduced in pressure, ventilated, and cooled. The resulting latex had a solids content of 24.6 wt%. After coagulation with Al2(SO4)3 solution and drying (1048 g), the Mooney viscosity (ML) (1+10) of the resulting fluoroelastomer aggregates was measured at 121°C at 48 MU.

[0123] Example 5 (According to the present invention) The same procedure as in Example 4 was followed, with the same initial HFP pressurization, subsequent pressurization with a VDF / HFP / TFE mixture, and the same initial filling with C4F8I2 (2.45 g) and bis-olefin of formula H2C=CH-(CF2)6-CH=CH2 (0.23 g). Initiation was achieved by pumping a 1.4 g / L solution of TBHP in desalinated water at a constant feed rate and separately pumping a 4 g / L solution of Bruggolite® type E28 in desalinated water at essentially the same feed rate.

[0124] After initiation, a VDF / HFP / TFE mixture was continuously supplied to maintain a constant pressure, and a total of 3.77 g of bis-olefin was added in 20 steps. 3.67 g of C4F8I2 was added at a monomer conversion rate of 240 g. A final aliquot of 2.04 g of C4F8I2 was introduced at a monomer conversion rate of 960 g.

[0125] Polymerization was continued until a total monomer consumption of 1200 g was reached after 238 minutes; during such reaction time, 218 mL and 212 mL of detailed solutions of E28 and THBP described above were supplied, respectively, and the autoclave was then reduced in pressure, aerated, and cooled. The resulting latex had a solids content of 22.5% by weight. After coagulation with Al2(SO4)3 solution and drying (935 g), the Mooney viscosity (ML) (1+10) of the resulting fluoroelastomer aggregates was measured at 121°C at 65 MU.

[0126] Example 6 (According to the present invention) After discharging 11.5 L of demineralized water, it was introduced into a 22 L vertical autoclave equipped with a stirrer operating at 450 rpm. The autoclave was then heated to 60°C and maintained at that temperature for the entire duration of the reaction. The autoclave pressure was increased to 13.7 bar by supplying HFP monomers. A gaseous mixture of the following monomers was supplied to the autoclave until the pressure reached 26 bar: vinylidene fluoride (VDF) 48.5 mol%, hexafluoropropene (HFP) 26.5 mol%, and tetrafluoroethylene (TFE) 25 mol%. Then, 10.61 g of C4F8I2 and 0.90 g of bis-olefin of the formula H2C=CH-(CF2)6-CH=CH2 were introduced. An 8.22 g / L solution of t-butyl hydroperoxide in the demineralized water was pumped into the autoclave at a constant supply rate. Simultaneously, but separately, a 23.5 g / L solution of Bruggolite® type E28 in desalinated water was pumped into the autoclave at essentially the same feed rate. After initiation, the VDF / HFP / TFE mixture was continuously fed to maintain a constant pressure, and a total of 16.49 g of bis-olefins was added in 19 steps. After the instantaneous monomer conversion rate exceeded 2000 g / hour, the feed rates of TBHP and Bruggolite® E28 decreased by approximately 25% and were maintained constant for the remainder of the reaction. 16.33 g of C4F8I2 was added at a monomer conversion rate of 1056 g. A final aliquot of 8.98 g of C4F8I2 was introduced at a monomer conversion rate of 4224 g.

[0127] Polymerization was continued until a total monomer consumption of 5280 g was reached after 212 minutes; during such reaction time, 209 mL and 204 mL of detailed solutions of E28 and THBP described above were supplied, respectively; the autoclave was then reduced in pressure, ventilated, and cooled. The resulting latex had a solids content of 26.6 wt%. After coagulation with Al2(SO4)3 solution and drying (4538 g), the Mooney viscosity (ML) (1+10) of the resulting fluoroelastomer aggregates was measured at 121°C at 23 MU.

[0128] Example 7 (According to the present invention) Following the same procedure as in Example 6, the same initial HFP pressurization, subsequent pressurization with the VDF / HFP / TFE mixture, and the same initial filling with C4F8I2 (10.61 g) and bis-olefin of formula H2C=CH-(CF2)6-CH=CH2 (0.90 g) were performed. Initiation was achieved by pumping an 8.22 g / L solution of TBHP in desalinated water at a constant feed rate and separately pumping a 17.3 g / L solution of Bruggolite® type E28 in desalinated water at essentially the same feed rate.

[0129] After initiation, a VDF / HFP / TFE mixture was continuously supplied to maintain a constant pressure, and a total of 16.53 g of bis-olefin was added in 20 steps. 16.33 g of C4F8I2 was added with a monomer conversion rate of 1056 g. A final aliquot of 8.98 g of C4F8I2 was introduced with a monomer conversion rate of 4224 g.

[0130] Polymerization was continued until a total monomer consumption of 5280 g was reached after 197 minutes; during such reaction time, 206 mL and 189 mL of detailed solutions of E28 and THBP, as detailed above, were supplied, respectively, and the autoclave was then reduced in pressure, ventilated, and cooled. The resulting latex had a solids content of 26.1% by weight. After coagulation with Al2(SO4)3 solution and drying (4453 g), the Mooney viscosity (ML) (1+10) of the resulting fluoroelastomer aggregates was measured at 121°C at 25 MU.

[0131] Table 1(a and b) summarizes the most relevant polymerization conditions in tabular form according to Comparative Example 1C, Comparative Example 2C, Comparative Example 3C, and Examples 4, 5, 6, and 7 according to the present invention.

[0132] [Table 1]

[0133] [Table 2]

[0134] Tables 2(a and b) summarize in tabular form the most relevant characteristics of the fluoroelastomers obtained from Comparative Examples 1C, 2C, 3C, and 4, 5, 6, and 7 of the present invention, including MDR and sealing properties, determined by adding the following curing components to the fluoroelastomers described above: 30 phr of Cancarb C-black N990 MT; 4.00 phr of triallyl isocyanurate (Drimix® TAIC 75, manufactured by Finco); 5.00 phr of ZnO (manufactured by Carlo Erba); and 3.00 phr of Luperox® 101 XL 45 (manufactured by Atofina).

[0135] Characterization of curing behavior The curing behavior was characterized at 160°C by a moving direometer (MDR) according to ASTM D 5289, by determining the following properties: M L = Minimum torque (pounds x inches) M H = Maximum Torque (pounds x inches) t s2 This is the scorch time, i.e., the torque is M L The time required to increase by 2 units from t 90 M H This is the time required to reach 90% of the goal.

[0136] O-rings (size class = 214) were formed and cured at 160°C for 10 minutes in a press die containing 12 cavities, and then post-treated in an air-circulating oven at 230°C (1 hour to reach setpoint T°, and 4 hours at setpoint T°). Forming was repeated three times for each recipe, and O-ring specimens were collected. Compression set (C-SET) was determined against O-ring specimen standard AS568A (type 214) according to ASTM D 395, Method B, over 70 hours at 200°C.

[0137] [Table 3]

[0138] (**)Attempts at molding were not effective in obtaining O-ring test specimens according to standard AS568A, making a significant C-Set determination impossible.

[0139] [Table 4]

[0140] By comparing the MDR behavior, the fluoroelastomers of Examples 4 to 7 of the present invention showed significantly higher M values ​​than the corresponding values ​​of the fluoroelastomers of Comparative Examples 1 to 3. H -M L It becomes possible to conclude that it has a value. Such a higher M H -M L The value represents the ability to reach a significantly higher crosslink density, and a lower t 90 As indicated by the values, they have a faster crosslinking rate. As far as C-set is concerned, the fluoroelastomers of Examples 4 to 7 of the present invention have significantly lower C-Set values ​​than the corresponding values ​​of the fluoroelastomers of Comparative Examples 1 to 3. Therefore, their sealing ability is significantly better than that of the comparative fluoroelastomers.

Claims

1. A method for producing a (per)fluoroelastomer [fluoroelastomer (A)] containing iodine chain termini and / or bromine chain termini, wherein the method comprises, in the presence of a chain transfer agent [agent (CTA-X)] having an I atom and / or a Br atom, and in the presence of a redox initiation system [system (R)] comprising at least one composition [composition (CS)] having at least one sulfinic acid group, at least one second (per)fluorinated monomer [monomer (M)] different from vinylidene fluoride (VDF), in an aqueous emulsion. Ｆ This includes polymerizing VDF in the presence of ) Here, - O in the initiator (O) ２ The amount is at least 1.50 and a maximum of 15.00 mmol per 1 kg of fluoroelastomer (A); - The amount of compound (S) is at least 0.20 and a maximum of 2.00 g per 1 kg of fluoroelastomer (A); and - The ratio of the drug (CTA-X) to the composition (CS) is at least 2.00 and at most 8.00 in terms of the weight of X / the weight of the composition (CS), where X is the amount of I and / or Br in the drug (CTA-X); and The polymerization described above is emulsion polymerization, and the emulsion polymerization is carried out without the addition of any fluorinated surfactant or hydrocarbon surfactant, and The molar ratio of the halogen content of (CTA-X) to the peroxide content of the initiator (O) is mol / O ２ The mol of is at least 3.00, and the mol / O of X ２ In mol, the maximum is 15.

00. method.

2. Monomer (M Ｆ ) However, the following: -C ２ ~C ８ Perfluoroolefin; - A hydrogen-containing C different from VDF ２ ~C ８ Fluoroolefin; -C ２ ~C ８ Chloro and / or bromo and / or iodofluoroolefins; -Formula CF ２ = CFOR ｆ (In the formula, R ｆ C １ ~C ６ (Per)fluoroalkyl vinyl ethers (PAVE) that are (per)fluoroalkyl groups; -Formula CF ２ =CFOX (where X is C containing a catenary oxygen atom) １ ~C １２ (Per)fluoro-oxyalkyl vinyl ethers (which are per)fluoro-oxyalkyl; -formula: 【Chemistry 1】 (In the formula, R is either equal to or different from each other) ｆ３ , R ｆ４ , R ｆ５ , R ｆ６ This is a carbon atom optionally containing a fluorine atom and one or more oxygen atoms. １ ~C ６ (Per)fluorodioxole having (independently selected from among per)fluoroalkyl groups; - (Per)fluoro-methoxy-vinyl ether having the following formula (hereinafter, MOVE): CFX ２ = CX ２ OCF ２ OR'' ｆ (In the formula, R'' ｆ C is either linear or branched. １ ~C ６ (Per)fluoroalkyl; C ５ ~C ６ Cyclic (per)fluoroalkyl; and linear or branched C, containing 1 to 3 catenary oxygen atoms. ２ ~C ６ Selected from (per)fluorooxyalkyl groups, X ２ (=F, H) Selected from the group consisting of, And / or The method according to claim 1, wherein the fluoroelastomer (A) comprises repeating units derived from hexafluoropropylene (HFP) in addition to repeating units derived from VDF.

3. - The aforementioned drug (CTA-X) is as follows: Iodinating and / or brominating organic chain transfer agent The organic chain transfer agent is of formula R ｆ (I) ｘ (Br) ｙ (In the formula, R ｆ However, it is a (per)fluoroalkyl or (per)fluorochloroalkyl containing 1 to 8 carbon atoms, while x and y are integers from 0 to 2 such that 1 ≤ x + y ≤ 2; and Alkali metal or alkaline earth metal iodides and / or bromides; Selected from the group consisting of, and / or - The aforementioned drug (CTA-X) is, formula R ｆ (I) ｘ (Br) ｙ (In the formula, R ｆ However, it is selected from the group of (per)fluoroalkyl or (per)fluorochloroalkyl elements containing 1 to 8 carbon atoms, while x and y are integers from 0 to 2 such that 1 ≤ x + y ≤ 2; and / or - The ratio of the drug (CTA-X) to the composition (CS) is at least 2.50 and at most 7.60 in terms of the weight of X / the weight of the composition (CS), where X is the amount of I and / or Br in the drug (CTA-X); and / or - The drug (CTA-X) is an iodation chain transfer agent, and the amounts of (CTA-X) and composition (CS) are such that the iodine / composition (CS) ratio is at least 2.00 and at most 7.60, in terms of weight of I / weight of composition (CS). The method according to claim 1 or 2.

4. The initiator (O) is as follows: (b) Diacyl peroxide; benzoylacetyl peroxide, diglutarate peroxide; (c) Dialkylperoxide; (d) Hydroperoxides; (e) Peracid esters and their salts; (f) Peroxydicarbonate Selected from the group consisting of, and / or In the initiator (O) mentioned above, O ２ The method according to any one of claims 1 to 3, wherein the amount is up to 12.00 mmol per 1 kg of fluoroelastomer (A); and / or at least 1.80 mmol per 1 kg of fluoroelastomer (A).

5. - The compound (S) is given by the following formula (S-I): 【Chemistry 4】 (In the formula, M is a hydrogen atom, an ammonium ion, or a monovalent metal ion; R ２０ However, -OH or -N(R ４ ) (Caution ５ ) and here, R is either identical or different to each other. ４ and R ５ Each of these is a linear or branched alkyl chain having a hydrogen atom or 1 to 6 carbon atoms; R ２１ However, it is a linear or branched alkyl group having a hydrogen atom, 1 to 6 carbon atoms, a 5 or 6-membered cycloalkyl group, or a 5 or 6-membered aryl group; R ２２ However, -COOM, -SO ３ M, -C(=O)R ４ , -C(=O)N(R ４ ) (Caution ５ ), -C(=O)OR ４ And here, M, R ４ and R ５ However, as defined above, and according to a salt thereof having at least one monovalent metal ion; and / or The composition (CS) contains a compound according to formula (S-I) as defined above, in an amount of up to 50% by weight of the total weight of the composition (CS); and / or The composition (CS) is a compound containing at least one sulfonic acid group [compound (S ３ )] further comprises the compound (S ３ ) is expressed in the following equation (S ３ -I): 【Transformation 5】 (In the formula, M, R ２０ , R ２１ and R ２２ However, it has the same meaning as defined above for compounds of formula (S-I); in particular, M is a monovalent metal ion; and / or The composition (CS) is at least 5% by weight of the total weight of the composition (CS), and is a compound of the formula (S) defined above. ３ - According to (including compounds according to I); and / or The composition (CS) is as follows: -Sulfites or salts thereof (also called "sulfites"), i.e., compounds of the formula MO-S(O)-OM, where each of M is equal to or different from one another, independent as detailed above, and M is H and / or Na; and - Sulfuric acid or its salt (also called "sulfate"), i.e., formula MO-S(O) ２ - A compound of OM, where each of M is equal to or different from each other, independent as detailed above, and M is H and / or Na, The method according to any one of claims 1 to 4, further comprising at least one of the above.

6. An aqueous latex comprising particles of at least one (per)fluoroelastomer [fluoroelastomer (A)] having iodine chain termini and / or bromine chain termini, wherein the fluoroelastomer (A) is VDF and at least one (per)fluorinated monomer [monomer (M)] different from VDF. Ｆ The fluoroelastomer (A) contains repeating units derived from ), It has a Mooney viscosity (ML) (1 + 10) of at least 10 MU at -121°C; - Fluoroelastomer (A) in amounts of less than 0 to 5 mmol / kg -CH ２ Including the OH chain terminus; --CF ２ H and -CF ２ CH ３ A hydrogen-containing chain end selected from the group consisting of the above is contained in an amount of 0.01 to 10 mmol per 1 kg of fluoroelastomer (A); - Formula -CH in an amount of at least 65 mol% relative to the total moles at the chain ends ２ -Includes the chain end of X (where X is I or Br), The latex is produced by emulsion polymerization without the addition of any fluorinated surfactant or hydrocarbon surfactant. Water-based latex.

7. The fluoroelastomer (A) has the following composition (in mole percent): (i) 35-85% vinylidene fluoride (VDF), 10-45% hexafluoropropene (HFP), 0-30% tetrafluoroethylene (TFE), 0-15% perfluoroalkyl vinyl ether (PAVE), 0-5% bis-olefin (OF), (ii) 50-80% vinylidene fluoride (VDF), 5-50% perfluoroalkyl vinyl ether (PAVE), 0-20% tetrafluoroethylene (TFE), 0-5% bis-olefin (OF); (iii) 20-30% vinylidene fluoride (VDF), C ２ ~C ８ Non-fluorinated olefin (Ol) 10-30%, hexafluoropropene (HFP) and / or perfluoroalkyl vinyl ether (PAVE) 18-27%, tetrafluoroethylene (TFE) 10-30%, bis-olefin (OF) 0-5%; tetrafluoroethylene (TFE) 50-80%, perfluoroalkyl vinyl ether (PAVE) 20-50%, bis-olefin (OF) 0-5%; (iv) Tetrafluoroethylene (TFE) 33-75%, perfluoroalkyl vinyl ether (PAVE) 15-45%, vinylidene fluoride (VDF) 5-30%, hexafluoropropene HFP 0-30%, bis-olefin (OF) 0-5%; (v) 35-85% vinylidene fluoride (VDF), 5-40% fluorovinyl ether (MOVE), 0-30% perfluoroalkyl vinyl ether (PAVE), 0-40% tetrafluoroethylene (TFE), 0-30% hexafluoropropene (HFP), 0-5% bis-olefin (OF) The latex according to claim 6, selected from the group consisting of those having the following characteristics.

8. A (per)fluoroelastomer [fluoroelastomer (A)] comprising iodine chain termini and / or bromine chain termini, wherein the fluoroelastomer (A) comprises VDF and at least one (per)fluorinated monomer [monomer (M)] different from VDF. Ｆ The fluoroelastomer (A) contains repeating units derived from ), It has a Mooney viscosity (ML) (1 + 10) of at least 10 MU at -121°C; - Fluoroelastomer (A) in amounts of less than 0 to 5 mmol / kg -CH ２ Including the OH chain terminus; --CF ２ H and -CF ２ CH ３ A hydrogen-containing chain end selected from the group consisting of the above is contained in an amount of 0.01 to 10 mmol per 1 kg of fluoroelastomer (A); - Formula -CH in an amount of at least 65 mol% relative to the total moles at the chain ends ２ -X (where X is I or Br) contains an I / Br end chain, The fluoroelastomer is produced by emulsion polymerization without the addition of any fluorinated surfactant or hydrocarbon surfactant. (Per)fluoroelastomer.

9. Formula-CF ２ H and -CF ２ CH ３ The total amount of the chain ends is less than 8 mmol / kg; and / or The above formula -CH ２ - The amount of X (where X is I or Br) at the end of the chain is at least 65 mol% of the total moles of the chain ends; and / or The fluoroelastomer (A) has a Mooney viscosity (ML) (1 + 10) of at least 10 Mooney units (MU) at 121°C, and / or a Mooney viscosity (ML) (1 + 10) of up to 80 MU at 121°C, as determined according to ASTM D1646. The fluoroelastomer (A) according to claim 8.

10. The fluoroelastomer (A) is composed of the following (in mol% units): (i) 35-85% vinylidene fluoride (VDF), 10-45% hexafluoropropene (HFP), 0-30% tetrafluoroethylene (TFE), 0-15% perfluoroalkyl vinyl ether (PAVE), 0-5% bis-olefin (OF), (ii) 50-80% vinylidene fluoride (VDF), 5-50% perfluoroalkyl vinyl ether (PAVE), 0-20% tetrafluoroethylene (TFE), 0-5% bis-olefin (OF); (iii) 20-30% vinylidene fluoride (VDF), C ２ ~C ８ Non-fluorinated olefin (Ol) 10-30%, hexafluoropropene (HFP) and / or perfluoroalkyl vinyl ether (PAVE) 18-27%, tetrafluoroethylene (TFE) 10-30%, bis-olefin (OF) 0-5%; tetrafluoroethylene (TFE) 50-80%, perfluoroalkyl vinyl ether (PAVE) 20-50%, bis-olefin (OF) 0-5%; (iv) Tetrafluoroethylene (TFE) 33-75%, perfluoroalkyl vinyl ether (PAVE) 15-45%, vinylidene fluoride (VDF) 5-30%, hexafluoropropene HFP 0-30%, bis-olefin (OF) 0-5%; (v) 35-85% vinylidene fluoride (VDF), 5-40% fluorovinyl ether (MOVE), 0-30% perfluoroalkyl vinyl ether (PAVE), 0-40% tetrafluoroethylene (TFE), 0-30% hexafluoropropene (HFP), 0-5% bis-olefin (OF) A fluoroelastomer (A) according to claim 8 or 9, selected from the group consisting of those having the following characteristics.

11. A curable composition, - At least one fluoroelastomer (A) according to any one of claims 8 to 10, - At least one organic peroxide, A curable composition containing the following:

12. A method for producing a cured article, wherein the method comprises processing and curing the curable composition described in claim 11.

13. A cured article obtained from the curable composition described in claim 11.

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