초록 ▼

The invention pertains to a low viscosity curable (per)fluoroelastomer fluoroelastomer (A) having a number-averaged molecular weight of 3 000 to 45 000, said (per)fluoroelastomer comprising at least 1% moles, with respect to the total moles of recurring units, of recurring units derived from at leas

The invention pertains to a low viscosity curable (per)fluoroelastomer fluoroelastomer (A) having a number-averaged molecular weight of 3 000 to 45 000, said (per)fluoroelastomer comprising at least 1% moles, with respect to the total moles of recurring units, of recurring units derived from at least one (per)fluoromethoxyalkylvinylether of formula (I): CFX′═CX″OCF2ORf  formula (I) wherein X′ and X″, equal to or different from each other, are independently H or F; and Rf is selected from the group consisting of C1-C6 (per)fluoroalkyls, linear or branched; C5-C6 cyclic (per)fluoroalkyls; and C2-C6 (per)fluorooxyalkyls, linear or branched, comprising from 1 to 3 catenary ethereal oxygen atoms monomer (M).

대표청구항 ▼

1. A low viscosity curable fluoroelastomer or (per)fluoroelastomer [fluoroelastomer (A)] having a number-averaged molecular weight of 3,000 to 45,000, said fluoroelastomer (A) comprising: at least 1% moles, with respect to the total moles of recurring units, of recurring units derived from at least

1. A low viscosity curable fluoroelastomer or (per)fluoroelastomer [fluoroelastomer (A)] having a number-averaged molecular weight of 3,000 to 45,000, said fluoroelastomer (A) comprising: at least 1% moles, with respect to the total moles of recurring units, of recurring units derived from at least one (per)fluoromethoxyalkylvinylether of formula (I): CFX′═CX″OCF2ORf  formula (I) wherein X′ and X″, equal to or different from each other, are independently H or F; and Rf is selected from the group consisting of C1-C6 (per)fluoroalkyls, linear or branched; C5-C6 cyclic (per)fluoroalkyls; and C2-C6 (per)fluorooxyalkyls, linear or branched, comprising from 1 to 3 catenary ethereal oxygen atoms [monomer (M)], recurring units derived from vinylidene fluoride (VDF), from tetrafluoroethylene (TFE), or from a combination thereof, and optionallyrecurring units derived from at least one additional (per)fluorinated monomer [comonomer (C)], wherein comonomer (C) is different from monomer (M), VDF and TFE. 2. The fluoroelastomer (A) of claim 1, wherein monomer (M) is a perfluoromethoxyalkylvinylether of formula (I): CF2═CFOCF2OR′f  formula (I)wherein R′f is selected from the group consisting of C1-C6 perfluoroalkyls, linear or branched; C5-C6 cyclic perfluoroalkyls; and C2-C6 perfluorooxyalkyls, linear or branched, comprising from 1 to 3 catenary ethereal oxygen atoms. 3. The fluoroelastomer of claim 2, wherein monomer (M) is selected from the group consisting of: CF2═CFOCF2O—CF3;  (M1)CF2═CFOCF2O—CF2CF3; and  (M2)CF2═CFOCF2O—CF2CF2OCF3.  (M3) 4. The fluoroelastomer (A) of claim 1, wherein comonomer (C) is selected from the group consisting of: C2-C8 fluoro- and/or perfluoroolefins;1,2-difluoroethylene, vinylidene fluoride (VDF) and trifluoroethylene (TrFE);(per)fluoroalkylethylenes complying with formula CH2═CH—Rf0, wherein Rf0 is a C1-C6 (per)fluoroalkyl or a C1-C6 (per)fluorooxyalkyl having one or more ether groups;chloro- and/or bromo- and/or iodo-C2-C6 fluoroolefins;fluoroalkylvinylethers complying with formula CF2═CFORf1 wherein Rf1 is a C1-C6 fluoro- or perfluoroalkyl;hydrofluoroalkylvinylethers complying with formula CH2═CFORf1 wherein Rf1 is a C1-C6 fluoro- or perfluoroalkyl;fluoro-oxyalkylvinylethers different from formula (I) and complying with formula CF2═CFOX0, wherein X0 is a C1-C12 oxyalkyl, or a C1-C12 (per)fluorooxyalkyl having one or more ether groups;functional fluoro-alkylvinylethers complying with formula CF2═CFOY0, wherein Y0 is a C1-C12 alkyl or (per)fluoroalkyl, or a C1-C12 oxyalkyl or a C1-C12 (per)fluorooxyalkyl, said Y0 group comprising a carboxylic or sulfonic acid group, in its acid, acid halide or salt form;fluorodioxoles, of formula: wherein each of Rf3, Rf4, Rf5, Rf6, equal or different each other, is independently a fluorine atom, a C1-C6 fluoro- or per(halo)fluoroalkyl, optionally comprising one or more oxygen atom, wherein: if the fluoroelastomer (A) is a VDF-based copolymer, comonomer (C) is not VDF; andif the fluoroelastomer (A) is a TFE-based copolymer, comonomer (C) is not TFE. 5. The fluoroelastomer (A) of claim 1, comprising at least 3% moles with respect to the total moles of recurring units, of recurring units derived from said monomer (M). 6. The fluoroelastomer (A) of claim 1, wherein the sum of recurring units derived from said monomer (M) and said comonomer (C) represents at least 10% moles, with respect to the total amount of recurring units of said fluoroelastomer (A). 7. The fluoroelastomer (A) of claim 6, said fluoroelastomer being selected from the group consisting of VDF-based copolymers comprising, with respect to total moles of recurring units of said fluoroelastomer (A): from 5 to 35% moles of recurring units derived from monomer (M);from 0.5 to 35% moles of recurring units derived from at least one C2-C8 perfluoroolefin; wherein the sum of recurring units derived from said monomer (M) and from the perfluoroolefin is of at least 10% moles; and from 90 to 30% moles of recurring units derived from said VDF. 8. The fluoroelastomer (A) of claim 1, having a number-averaged molecular weight of at least 7,000. 9. The fluoroelastomer (A) of claim 1, having a number-averaged molecular weight of at most 40,000. 10. The fluoroelastomer (A) of claim 1, further comprising cure sites as pendant groups bonded to certain recurring units. 11. The fluoroelastomer (A) of claim 10, wherein said cure-site containing recurring units are selected from the group consisting of: (CSM-1) iodine or bromine containing monomers of formula: wherein each of AHf, equal to or different from each other and at each occurrence, is independently selected from F, Cl, and H; BHf is any of F, Cl, H and ORHfB, wherein RHfB is a branched or straight chain alkyl radical which can be partially, substantially or completely fluorinated or chlorinated; each of WHf equal to or different from each other and at each occurrence, is independently a covalent bond or an oxygen atom; EHf is a divalent group having 2 to 10 carbon atom, optionally fluorinated; RHf is a branched or straight chain alkyl radical, which can be partially, substantially or completely fluorinated; and XHf is a halogen atom selected from the group consisting of Iodine and Bromine; which may be inserted with ether linkages; and (CSM-2) ethylenically unsaturated compounds comprising cyanide groups, optionally fluorinated. 12. The fluoroelastomer (A) of claim 1, further comprising iodine or bromine cure sites in an amount of 0.001 to 10% wt. 13. The fluoroelastomer (A) of claim 12, wherein said iodine or bromine cure sites comprise pendant groups bound to the backbone of the fluoroelastomer (A) polymer chain and/or comprise terminal groups of said polymer chain. 14. The fluoroelastomer (A) of claim 12, wherein said fluoroelastomer (A) is obtained by addition to the polymerization medium during fluoroelastomer manufacture of anyone of: iodinated and/or brominated chain-transfer agent(s); suitable chain-chain transfer agents are typically those of formula Rf(I)x(Br)y, wherein Rf is a (per)fluoroalkyl or a (per)fluorochloroalkyl containing from 1 to 8 carbon atoms, while x and y are integers between 0 and 2, with 1≦x+y≦2; andalkali metal or alkaline-earth metal iodides and/or bromides.