Process for producing a fluoropolymer

Abstract

The present invention relates to the use of an additive A 2 as an anti-fouling agent in a process for producing a fluoropolymer P 1. The present invention also relates to the implementation of a process for producing a fluoropolymer P1 in the presence of said additive A2.

Description

Title of the invention: Process for producing a fluoropolymer Technical field

[0001] The present invention relates to a method for producing a fluoropolymer. In particular, the present invention relates to a method for producing a fluoropolymer in the presence of an antifouling agent. Technological background of the invention

[0002] Fluoropolymers exhibit excellent mechanical and thermal properties, in addition to their exceptional chemical inertness. They are used in high-performance applications such as lithium-ion batteries, coatings, or water treatment. Fluoropolymers are notably prepared by aqueous emulsion of free radicals or suspension polymerization. Among the fluoropolymers, vinylidene fluoride is of particular importance in applications related to new energies. Since vinylidene fluoride is a gas or a supercritical fluid depending on the polymerization process, the polymerization mechanism can be more complex than most emulsion polymerization processes.However, the overall polymerization mechanism follows the standard emulsion polymerization process and the recipe includes water, vinylidene fluoride, a surfactant, a water-soluble initiator, and some additives (chain transfer agent, buffer, antifouling agent). The polymerization takes place in a high-pressure reactor, where vinylidene fluoride is initially present in both the gas and aqueous phases, and in the PVDF particles during polymerization.

[0003] Polyvinylidene fluoride (PVDF) is used as a binder in lithium-ion batteries due to its excellent electrochemical stability, good binding capacity, and strong adhesion to electrode materials and current collectors. In wet-slurry processes for preparing an electrode, the active materials and binders are dispersed in a liquid solution. The liquid solution is usually based on organic solvents or water. The dispersion is cast onto a current collector and then dried in a high-temperature oven to produce an electrode. Unfortunately, the excellent properties provided by fluoropolymers such as PVDF can also limit the applications in which they can be used. For example, it is difficult to adhere fluoropolymers to other materials.Therefore, organic solvents and other organic additives are generally used in a coating formulation to provide good adhesion (non-reversible adhesion) between PVDF-based polymers, a porous separator or an electrode, and possibly . powder particles added. Alternatively, fluoropolymer binders can carry functional groups to promote the adhesive behavior of the polymer. The functional groups are usually introduced by a functionalized vinyl compound used as a comonomer during the production of the fluoropolymer. However, the use of these functionalized vinyl compounds leads to significant fouling of the reactor during the polymerization step.

[0004] Therefore, it is necessary to find new solutions for the production of fluoropolymers by limiting the fouling of the reactor during polymerization. Summary of the invention

[0005] According to a first aspect, the present invention relates to a process for producing a fluoropolymer PI comprising a step of polymerizing, in a reactor, a fluoromonomer Mla and a monomer Mlb in the presence of an initiator and from 0.05% to 50% by weight of an additive A2 based on the total weight of fluoromonomer Mla; said additive A2 comprising repeating units derived from a monomer M 2 ; said monomer Mlb and said monomer M2 are independently of each other of formula (I), (II), (III), (IV), (V) or a mixture thereof

[0006] R1R2C=C(R3)((X2)PC(O)R4) (I)

[0007] R5R6C=C(R7)(OC(O)R8) (II)

[0008] R9R10C=CRnC(O)OC(O)CR12=CR13R14 (III)

[0009] R30R31C=CR32(CN) (VI)

[0010] R33R34C=CR35(C(O)NR36R37) (VII)

[0011] in which

[0012] R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and C1-C5 alkyl;

[0013] R4 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 and -OR25 with R25 selected from the group consisting of H and C1-C18 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, SO3H, -OPO32, -C(O)OR25, -OC(O)R25, and a five or six membered heterocycle comprising at least one nitrogen atom in its ring chain;

[0014] R25 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted by one or more CO2H functional groups;

[0015] X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wr and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R26, R27, R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl;

[0016] p' is 0 or 1;

[0017] R5, R6 and R7 are independently of each other selected from the group consisting of H and C1-C5 alkyl;

[0018]

[0019] R8 is C1-C5 alkyl; R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R30 R31 R32 , R , R , R are independently of each other selected from the group consisting of H and C1-C5 alkyl, preferably selected from the group consisting of H and CH3;

[0020] R36 and R37 are, independently of each other, selected from the group consisting of H and C1-C10 alkyl optionally substituted by one or more groups -OH, -CO2H, SO3H, -OPO32, -C(O)OR38, -OC(O)R38; R38 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted by one or more functional groups CO2H.

[0021] According to a preferred embodiment, said monomer M1 b is of formula R1R2C=C(R3)((X2)PC(O)R4) in which the substituents R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2 H and C1-C5 alkyl; R4 is selected from the group consisting of -NHC(CH3)2CH 2C(O)CH3 or -OR25 with R25 selected from the group consisting of H and C1-C18 alkyl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H, -OC(O)R25, -C(O)O-R25 or a five- or ten-membered heterocycle comprising at least one nitrogen atom in its ring chain; R25 being selected from the group consisting of C1-C6 alkyl or C6-C12 aryl optionally substituted by one or more group(s) -OH, -CO2H, -SO3H, -PO3H; p' is 0 or 1;X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]W 1- and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R26, R27, ; R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl.

[0022] According to a preferred embodiment, said monomer Mlb is added, into said reactor, in the form of an aqueous solution and continuously.

[0023] According to a preferred embodiment, said additive A2 is added before the initiation of the reaction when the pressure in said reactor is lower than the critical pressure of vinylidene fluoride or is added continuously in said reactor.

[0024] According to a preferred embodiment, said additive A2 is water-soluble.

[0025] According to a preferred embodiment, said selected fluorinated monomer Mla from the group consisting of vinyl fluoride; vinylidene fluoride (VDF); trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) and perfluoro(propyl vinyl) ether (PPVE); perfluoro(l,3-dioxole); perfluoro(2,2-dimethyl-l,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2 X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R1CH2OCF=CF2 in which R1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product of formula R2OCF=CH 2 in which R2 is F(CF2)p and p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE);trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof. ;

[0026] According to a preferred embodiment, said monomer Mla is vinylidene fluoride.

[0027] According to a preferred embodiment, said monomer M1 b is of formula R1R2C=C(R3)((X2)PC(O)R4) in which the substituents R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2 H and CrC3 alkyl; R4 is -OR25 with R25 selected from the group consisting of H and C1-C10 alkyl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H, -OC(O)R25, -C(O)O-R25; R25 being selected from the group consisting of C1-C5 alkyl or C6 aryl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H; p' is 0 or 1; X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]W r and a C1-C5 alkyl hydrocarbon group optionally carrying one or more group(s) -OH, -CO2H or ester(s); with wl being an integer from 1 to 5; R26, R27, R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and CrC3 alkyl.

[0028] According to a preferred embodiment, said additive A2 comprises repeating units derived from a monomer M2 of formula (I), (II), (VI), (VII) or a mixture thereof

[0029] R1R2C=C(R3)((X2)p -C(O)R4) (I)

[0030] R5R6C=C(R7)(OC(O)R8) (II)

[0031] R30R31C=CR32(CN) (VI)

[0032] R33R34C=CR35(C(O)NR36R37) (VII)

[0033] in which

[0034] R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and C1-C5 alkyl;

[0035] R4 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 and -OR25 with R25 selected from the group consisting of H and CrCi8 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, -SO3H, -OPO32, -C(O)OR25, -OC(O)R25, and a five or six membered heterocycle comprising at least one nitrogen atom in its ring chain;

[0036] R25' is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted by one or more CO2H functional groups;

[0037] X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wr and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R26, R27, R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl;

[0038] p' is 0 or 1;

[0039] R5, R6 and R7 are independently of each other selected from the group consisting of H and C1-C5 alkyl;

[0040] R8 is CrC5 alkyl;

[0041] R30, R31, R32, R33, R34, R35 are independently of each other selected from the group consisting of H and C1-C5 alkyl, preferably selected from the group consisting of H and CH3;

[0042] R36 and R37 are, independently of each other, selected from the group consisting of H and Ci-Cio alkyl optionally substituted by one or more groups -OH, -CO2H, SO3H, -OPO32, -C(O)OR38, -OC(O)R38; R38 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted with one or more CO2H functional groups.

[0043] According to a preferred embodiment, said additive A2 comprises repeating units derived from a monomer M2 of formula R'R2C=C(R3)(C(O)R4) (I) in which

[0044] R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and C1-C3 alkyl;

[0045] R4 is -OR25 with R25 selected from the group consisting of H and C1-C5 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, -SO3H, -OPO32, -C(O)OR25, -OC(O)R25;

[0046] R25 is selected from the group consisting of C1-C5 alkyl and C6 substituted aryl by one or more CO2H functional groups.

[0047] According to another aspect, the present invention relates to the use of an additive A2 as defined in the present application as an anti-fouling agent in a process for producing a fluoropolymer PI.

[0048] According to a preferred embodiment, said fluoropolymer PI comprises repeating units derived from a fluorinated monomer Mla selected from the group consisting of vinyl fluoride; vinylidene fluoride (VDF); trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) and perfluoro(propyl vinyl) ether (PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2 =CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R1CH2OCF=CF2 in which R1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product of formula R2OCF=CH2 in which R2 is F(CF2)p and p is 1, 2, 3 or 4;perfluorobutylethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof. ;

[0049] According to a preferred embodiment, said fluorinated polymer PI comprises repeating units derived from a fluorinated monomer Mla being vinylidene fluoride.

[0050] According to a preferred embodiment, said fluorinated polymer PI also comprises repeating units derived from a monomer M1 b as defined in the present application.

[0051] According to a preferred embodiment, said fluoropolymer PI also comprises repeating units derived from a monomer Mlb of formula R'R2C=C(R3)(C(O)R4 ) in which the substituents R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and Ci-C3 alkyl; R4 is -OR25 with R25 selected from the group consisting of H and Ci-Cio alkyl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H, -OC(O)R25, -C(O)O-; Rd” being selected from the group consisting of C1-C5 alkyl or C6 aryl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO 3H. Detailed description of the invention

[0052] The present invention makes it possible to prepare a functionalized fluoropolymer while avoiding the problems of reactor fouling which can occur during polymerization reactions.

[0053] According to a first aspect of the present invention, a method for producing a fluorinated polymer PI is provided. Said method comprises a step of polymerizing, in a reactor, a fluorinated monomer Mla and a monomer Mlb.

[0054] Fluorinated monomer Mla

[0055] Said fluorinated monomer Mla used in the present method is selected from the group consisting of vinyl fluoride; vinylidene fluoride (VDF); trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) and perfluoro(propyl vinyl) ether (PPVE); perfluoro(l,3-dioxole); perfluoro(2,2-dimethyl-l,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2 X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R1CH2OCF=CF2 in which R1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product of formula R2OCF=CH 2 in which R2 is F(CF2)p and p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE);trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof. Among the trifluoropropenes, mention may be made of 3,3,3-trifluoropropene. ; Among the tetrafluoropropenes, we can cite 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene. Among the pentafluoropropenes, we can cite 1,1,3,3,3-pentafluoropropene or 1,2,3,3,3-pentafluoropropene. Chlorofluoroethylene can denote either 1-chloro-1-fluoroethylene or 1-chloro-2-fluoroethylene. The 1-chloro-1-fluoroethylene isomer is preferred. Chlorotrifluoropropene is preferably 1-chloro-3,3,3-trifluoropropene or 2-chloro-3,3,3-trifluoropropene.

[0056] Preferably, said monomer Mla is selected from the group consisting of vinyl fluoride, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene and hexafluoropropylene. In particular, said monomer Mla is vinylidene fluoride.

[0057] Monomer Mlb

[0058] According to a preferred embodiment, said process is carried out in the presence of a monomer Mlb. Said monomer Mlb may be of formula (I), (II), (III), (IV), (V), (VI) or (VII) or a mixture thereof.

[0059] R1R2C=C(R3)((X2)PC(O)R4) (I)

[0060] R5R6C=C(R7)(OC(O)R8) (II)

[0061] R9R10C=CRnC(O)OC(O)CR12=CR13R14 (III)

[0062] R30R31C=CR32(CN) (VI)

[0063] R33R34C=CR35(C(O)NR36R37) (VII)

[0064] in which

[0065] R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and C1-C5 alkyl;

[0066] R4 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 and -OR25 with R25 selected from the group consisting of H and CrCi8 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, SO3H, -OPO32, -C(O)OR25, -OC(O)R25, and a five or six membered heterocycle comprising at least one nitrogen atom in its ring chain;

[0067] R25 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted by one or more CO2H functional groups;

[0068] X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wr and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R26, R27,

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077] R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl; p' is 0 or 1; R5, R6 and R7 are independently selected from the group consisting of H and C1-C5 alkyl; R8 is C1-C5 alkyl; R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R30 R31 R32 33 34 35 , R , R , R are independently of each other selected from the group consisting of H and C1-C5 alkyl, preferably selected from the group consisting of H and CH3; R36 and R37 are, independently of each other, selected from the group consisting of H and C1-C10 alkyl optionally substituted by one or more -OH, -CO2H, SO3H, -OPO32, -C(O)OR38, -OC(O)R38 groups; R38 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted by one or more CO2H functional groups. Preferably, said monomer Mlb may be of formula (I), (II), (III), (IV), (V), (VI) or (VII) or a mixture thereof. R1R2C=C(R3)((X2)PC(O)R4) (I) R5R6C=C(R7)(OC(O)R8) (II) R9R10C=CR11C(O)OC(O)CR12=CR13R14 (III)

[0078]

[0079]

[0080]

[0081]

[0082]

[0083] R30R31C=CR32(CN) (VI) r33r34C=CR35(C(O)NR36R37) (VII) in which R1, R2 and R3 are independently selected from the group consisting of H, CO2H and C1-C5 alkyl; R4 is -OR25 with R25 selected from the group consisting of H and CrCi 0 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, SO3H, -OPO32, -C(O)OR25, -OC(O)R25; R25 is selected from the group consisting of C1-C5 alkyl and C6-C10 aryl substituted with one or more CO2H functional groups;

[0084] X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wl- and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 5; R 26 27 28 29 , R , R , R are independently of each other, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl;

[0085] p' is 0 or 1;

[0086] R5, R6 and R7 are independently of each other selected from the group consisting of H and C1-C3 alkyl;

[0087]

[0088] R8 is CrC3 alkyl; R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R30 R31 R32 33 34 35 , R , R , R are independently of each other selected from the group consisting of H and CrC3 alkyl, preferably selected from the group consisting of H and CH3;

[0089] R36 and R37 are, independently of each other, selected from the group consisting of H and C1-C5 alkyl optionally substituted by one or more groups -OH, -CO2H, SO3H, -OPO32, -C(O)OR38, -OC(O)R38; R38 is selected from the group consisting of C1-C3 alkyl and C6-C10 aryl substituted by one or more CO2H functional groups.

[0090] According to a particular embodiment, said monomer Mlb is of formula R*R2 C=C(R )((X )PC(O)R ) in which the substituents R , and R are independently of each other selected from the group consisting of H, CO2H and Ci-C5 alkyl; R4 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 or -OR25 with R25 selected from the group consisting of H and CrCi8 alkyl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H, -OC(O)R25, -C(O)O-R25 or a five- or ten-membered heterocycle comprising at least one nitrogen atom in its cyclic chain; R25 being selected from the group consisting of C1-C6 alkyl or C6-C12 aryl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H; p' is 0 or 1;X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]W r and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO 2H or ester group(s); with w1 being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular beyond 5;R ,R ,R ,R are independently of each other, independently for each unit w2, selected from the group consisting of H and C1-C5 alkyl. Said heterocycle may be saturated or unsaturated or aromatic. Said heterocycle may be monocyclic or bicyclic. Said ; heterocycle may be a pyrrole, pyrrolidine, pyridine, piperidine, pyrimidine, pyrazine, 1,4-dihydropyridine, indole, oxindole, isatin, quinoline, isoquinoline, quinazoline, imidazoline, pyrazolidine, 2-pyrrolidone, deltalactam, succinimide, 2-imidazolidinone, 4-imidazolidinone ring. Said heterocycle may be substituted by one or more C1-C5 alkyl groups. As mentioned above, the CrCi8 alkyl is optionally substituted by said heterocycle. The latter may be linked to the alkyl chain by the nitrogen atom or any other atom forming the heterocycle. Preferably the heterocycle is 2-pyrrolidone, delta-lactam, succinimide, 2-imidazolidinone, 4-imidazolidinone.

[0091] Advantageously, said monomer M 1b may be of formula R'R2C=C(R3)((X 2 4 12 3 )PC(O)R ) wherein the substituents R , R and R are independently selected from the group consisting of H, CO2H and C1-C5 alkyl; R4 is -OR25 with R25 selected from the group consisting of H and C1-C8 alkyl optionally substituted with one or more groups -OH, -CO2H, -SO3H, -PO3H, -OC(O)R25, -C(O)O-R25 or a five- or ten-membered heterocycle comprising at least one nitrogen atom in its ring chain; R25 being selected from the group consisting of C1-C6 alkyl or C6-C12 aryl optionally substituted with one or more groups -OH, -CO2H, -SO3H, -PO3H; p' is 0 or 1; X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]W r and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with w1 being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular beyond 5;R ,R ,R ,R are independently of each other, independently for each wl unit, selected from the group consisting of H and C 1-C 5 alkyl. ;

[0092] Preferably, said monomer M 1b may be of formula R1R2C=C(R3)((X2)P' C(O)R4) in which the substituents R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and C1-C5 alkyl; R4 is -OR25 with R25 selected from the group consisting of H and C1-C5 alkyl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO 3H, -OC(O)R25, -C(O)O-R25; R25 being selected from the group consisting of C1-C5 alkyl or C6-C10 aryl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H; p' is 0 or 1; X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]W r and a C 1 -C 10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with w1 being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular beyond 5;R ,R ,R ,R are independently one of the following: others, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl.

[0093] More preferably, said monomer M 1b may be of formula R'R^^CR3 )((X )PC(O)R ) in which the substituents R , R and R are independently of each other selected from the group consisting of H, CO2H and Ci-C3 alkyl; R4 is -OR25 with R25 selected from the group consisting of H and CrCi 0 alkyl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO 3H, -OC(O)R25, -C(O)O-R25; R25 being selected from the group consisting of CrC 5 alkyl or C6 aryl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H; p' is 0 or 1; X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wr and a C1-C5 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 5;R ,R ,R ,R are independently of each other, independently for each wl unit, selected from the group consisting of H and CrC3 alkyl. ;

[0094] In particular, said monomer M 1b may be of formula R1R2C=C(R3)((X2)PC(O)R 4) in which the substituents R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and C1-C3 alkyl; R4 is -OR25 with R25 selected from the group consisting of H and C1-C3 alkyl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H, -OC(O)R25, -C(O)O-R25; R25 being selected from the group consisting of C1-C5 alkyl or C6 aryl optionally substituted by one or more groups -OH, -CO2H, -SO3 H, -PO3H.

[0095] More particularly, said monomer M 1b may be acrylic acid, methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-dodecyl acrylate, amyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, diacetone acrylamide, lauryl acrylate, n-octyl acrylate, hydroxypropyl methacrylate, hydroxybutyl methacrylate, hydroxyethyl methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, methyl acrylic acid, methyl methacrylate, ethyl methacrylate, methacrylate propyl, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-dodecyl methacrylate, amyl methacrylate, isoamyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, n-octyl methacrylate,ureido methacrylate, monomers of formula CH2=CH(CO2CH2CH2CO2H), CH2=CH(CO2CH2CH2-OC(O)- , CH2CH2CO2H), CH2=CH(CO2CH2CH2CH2-OC(O)-CH2CH2CO2H), CH2=CH(CO2 CH(CH3)CH2-OC(O)-CH2CH2CO2H),CH2=CH(CO2CH2CH2-OC(O)-C6H4CO2H), CH2=CH(CO2CH2CH2CH2CH(CO2H)CH2CH2CO2H); and mixtures thereof.

[0096] Monomer Mlc

[0097] Said method can also be carried out in the presence of a monomer Ml c, different from the monomer Mla. Preferably, said monomer Mlc is selected from the group consisting of vinyl fluoride, vinylidene fluoride, trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) and perfluoro(propyl vinyl) ether (PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R1CH2OCF=CF2 in which R1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4; the product of formula R2 OCF=CH2 in which R2 is F(CF2)p and p is 1, 2, 3 or 4;perfluorobutyl ethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof. More preferably, when said monomer Mla is vinylidene fluoride, said fluorinated monomer Ml c selected from the group consisting of vinyl fluoride; trifluoroethylene; chlorotrifluoroethylene; 1,2-difluoroethylene, tetrafluoroethylene; hexafluoropropylene; perfluoro(alkyl vinyl)ethers such as perfluoro(methyl vinyl)ether, perfluoro(ethyl vinyl)ether or perfluoro(propyl vinyl)ether; perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF 2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5;the product of formula R'CH2OCF=CF2 in which R' is hydrogen or F(CF2 )z and z is 1, 2, 3 or 4; the product of formula R”OCF=CH2 in which R” is F(CF2 )z and z is 1, 2, 3 or 4; trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene or 2-trifluoromethyl-3,3,3-trifluoro-1-propene or a mixture thereof. In particular, when said monomer Mla is vinylidene fluoride, said fluorinated monomer Ml c is selected from; group consisting of trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene and hexafluoropropylene or a mixture thereof.

[0098] Additive A2

[0099] As mentioned above, in the present process, an additive A2 is added. This acts as an anti-fouling agent for the reactor.

[0100] According to a preferred embodiment, said additive A2 comprises repeating units derived from a monomer M2 of formula (I), (II), (III), (IV), (V), (VI), (VII) or a mixture thereof

[0101] R1R2C=C(R3)((X2)PC(O)R4) (I)

[0102] R5R6C=C(R7)(OC(O)R8) (II)

[0103] R9R10C=CRnC(O)OC(O)CR12=CR13R14 (III)

[0104] R30R31C=CR32(CN) (VI)

[0105] R33R34C=CR35(C(O)NR36R37) (VII)

[0106] in which

[0107] R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and C1-C5 alkyl;

[0108] R4 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 and -OR25 with R25 selected from the group consisting of H and CrCi8 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, SO3H, -OPO32, -C(O)OR25, -OC(O)R25, and a five or six membered heterocycle comprising at least one nitrogen atom in its ring chain;

[0109] R25 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted by one or more CO2H functional groups;

[0110] X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wr and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R26, R27, R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl; [YES] p' is 0 or 1;

[0112]

[0113]

[0114]

[0115]

[0116]

[0117]

[0118]

[0119] R5, R6 and R7 are independently selected from the group consisting of H and C1-C5 alkyl; R8 is C1-C5 alkyl; R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R30 R31 R32 33 34 35 , R , R , R are independently of each other selected from the group consisting of H and C1-C5 alkyl, preferably selected from the group consisting of H and CH3; R36 and R37 are, independently of each other, selected from the group consisting of H and C1-C10 alkyl optionally substituted by one or more -OH, -CO2H, SO3H, -OPO32, -C(O)OR38, -OC(O)R38 groups; R38 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted by one or more CO2H functional groups. Advantageously, additive A2 comprises repeating units derived from a monomer M2 of formula (I), (II), (III), (IV), (V), (VI), (VII) or a mixture thereof. R1R2C=C(R3)((X2)PC(O)R4) (I) R5R6C=C(R7)(OC(O)R8) (II) R9R10C=CR* 1C(O)OC(O)CR12=CR13R14 (III)

[0120]

[0121]

[0122]

[0123]

[0124]

[0125] R30R31C=CR32(CN) (VI) R33R34C=CR35(C(O)NR36R37) (VII) in which R1, R2 and R3 are independently selected from the group consisting of H, CO2H and C1-C5 alkyl; R4 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 and -OR25 with R25 selected from the group consisting of H and CrCi 5 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, SO3H, -OPO32, -C(O)OR25, -OC(O)R25, and a five or six membered heterocycle comprising at least one nitrogen atom in its ring chain; R25 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted with one or more CO2H functional groups;

[0126] X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wr and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 10, 26 27 28 29 in particular beyond5;R ,R ,R ,R are independently of each other, independently for each wl unit, selected from the group consisting of H and Ci-C5 alkyl;

[0127] p' is 0 or 1;

[0128] R5, R6 and R7 are independently of each other selected from the group consisting of H and C1-C3 alkyl;

[0129]

[0130] R8 is CrC3 alkyl; R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 R30 R31 R32 33 34 35 , R , R , R are independently of each other selected from the group consisting of H and C1-C3 alkyl, preferably selected from the group consisting of H and CH3;

[0131] R36 and R37 are, independently of each other, selected from the group consisting of H and C1-C5 alkyl optionally substituted by one or more groups -OH, -CO2H, SO3H, -OPO32, -C(O)OR38, -OC(O)R38; R38 is selected from the group consisting of C1-C5 alkyl and C6-Ci2 aryl substituted by one or more functional groups CO2H.

[0132] Preferably, said additive A2 comprises repeating units derived from a monomer M2 of formula (I), (II), (VI), (VII) or a mixture thereof.

[0133] R1R2C=C(R3)((X2)PC(O)R4) (I)

[0134] R5R6C=C(R7)(OC(O)R8) (II)

[0135] R30R31C=CR32(CN) (VI)

[0136] R33R34C=CR35(C(O)NR36R37) (VII)

[0137] in which

[0138] R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and C1-C5 alkyl;

[0139] R4 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 and -OR25 with R25 selected from the group consisting of H and C1-C18 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, -SO3H, -OPO32, -C(O)OR25, -OC(O)R25, and a five or six membered heterocycle comprising at least one nitrogen atom in its ring chain;

[0140] R25 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted by one or more CO2H functional groups;

[0141] X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wr and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R26, R27, R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl;

[0142] p' is 0 or 1;

[0143] R5, R6 and R7 are independently of each other selected from the group consisting of H and C1-C5 alkyl;

[0144] R8 is CrC5 alkyl;

[0145] R30, R31, R32, R33, R34, R35 are independently of each other selected from the group consisting of H and C1-C5 alkyl, preferably selected from the group consisting of H and CH3;

[0146] R36 and R37 are, independently of each other, selected from the group consisting of H and C1-C10 alkyl optionally substituted by one or more groups -OH, -CO2H, SO3H, -OPO32, -C(O)OR38, -OC(O)R38; R38 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted by one or more functional groups CO2H.

[0147] More preferably, said additive A 2 is of formula R'R2C=C(R3)((X2)p -C(O)R 4) (I) in which R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and Ci-C3 alkyl;

[0148] R4 is -OR25 with R25 selected from the group consisting of H and C1-C15 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, SO3H, -OPO32, -C(O)OR25, -OC(O)R25, and a five or six membered heterocycle comprising at least one nitrogen atom in its ring chain;

[0149] R25 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted by one or more CO2H functional groups;

[0150] X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wr and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R26, R27, R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl;

[0151] p' is 0 or 1.

[0152] In particular, said additive A 2 is of formula R1R2C=C(R3)((X2)PC(O)R4) (I) in which R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and Ci-C3 alkyl;

[0153] R4 is -OR25 with R25 selected from the group consisting of H and C1-C10 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, SO3H, -OPO32, -C(O)OR25, -OC(O)R25, and a five or six membered heterocycle comprising at least one nitrogen atom in its ring chain;

[0154] R25 is selected from the group consisting of C1-C5 alkyl and C6 substituted aryl by one or more CO2H functional groups;

[0155] X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wr and a C1-C5 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 5; R26, R27, R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl;

[0156] p' is 0 or 1.

[0157] More particularly, additive A 2 comprises repeating units derived from a monomer M2 of formula (I) R1R2C=C(R3)((X2)PC(O)R4) (I) in which

[0158] R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and CrC3 alkyl;

[0159] R4 is -OR25 with R25 selected from the group consisting of H and C1-C10 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, SO3H, -OPO32, -C(O)OR25, -OC(O)R25;

[0160] R25 is selected from the group consisting of C1-C5 alkyl and C6 substituted aryl by one or more CO2H functional groups;

[0161] X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wr and a C1-C5 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being an integer from 1 to 5; R26, R27, R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl;

[0162] p'est 0 yes.

[0163] Preferably, additive A 2 comprises repeating units derived from a monomer M2 of formula (I) R'R2C=C(R3)(C(O)R4) (I) in which

[0164] R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and C1-C3 alkyl;

[0165] R4 is -OR25 with R25 selected from the group consisting of H and CrCi 0 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, SO3H, -OPO32, -C(O)OR25, -OC(O)R25;

[0166] R25 is selected from the group consisting of C1-C3 alkyl and C6 substituted aryl by one or more CO2H functional groups.

[0167] According to one embodiment, said additive A 2 is a homopolymer of said monomer M2 according to any one of formulas (I) to (VII) above. According to another embodiment, said additive A 2 is a copolymer of several monomers M2 according to any one of formulas (I) to (VII) above. By copolymer is meant repeating units derived from at least two monomers M2 according to any one of formulas (I) to (VII) above.

[0168] Said additive A 2 may have a molar mass by weight of between 500 g / mol and 10000000 g / mol, advantageously between 600 g / mol and 9000000 g / mol, preferably between 700 g / mol and 8000000 g / mol, more preferably between 700 g / mol and 7000000 g / mol, in particular between 800 g / mol and 6000000 g / mol, more particularly between 900 g / mol and 5000000 g / mol, preferably between 1000 g / mol and 4000000 g / mol. The molecular or molar mass is determined by Size Exclusion Chromatography (CES). A test portion of the polymer solution corresponding to 90 mg of dry matter is introduced into a 10 mL bottle. Mobile phase, containing 0.04% dimethylformamide (DMF), is added to a total mass of 10 g. The composition of this mobile phase is as follows: NaHCO3: 0.05 mol / L, NaNO3: 0.1 mol / L, triethanolamine: 0.02 mol / L, NaN3 0.03% by mass.The CES system consists of a Waters 510 isocratic pump with a flow rate set at 0.8 mL / min, a Waters 717+ autosampler, an oven containing a 6 cm long, 40 mm inner diameter Waters Guard Column Ultrahydrogel precolumn, followed by a 30 cm long, 7.8 mm inner diameter Waters Ultrahydrogel linear column. Detection is performed using a Waters RI 410 differential refractometer. The oven is heated to 60°C and the refractometer is heated to 45°C. The CES device is calibrated with a series of sodium polyacrylate standards supplied by Polymer Standards Service with a peak molecular weight between 1000 g / mol and 1.106 g / mol and a polydispersity index between 1.4 and 1.7. The calibration curve is linear and takes into account the correction obtained using the flow marker: dimethylformamide (DMF).

[0169] Method

[0170] The polymerization step may be carried out at a temperature above the critical temperature of the monomers used therein. The polymerization step can be carried out at a temperature above 20°C, advantageously above 30°C, preferably above 40°C. The polymerization step can be carried out at a temperature of 20°C to 120°C, preferably 30°C to 110°C, in particular 40°C to 90°C.

[0171] The polymerization step can be carried out over a wide pressure range. Generally, the polymerization step can be carried out at a pressure of 10 to 150 bara, advantageously at a pressure of 15 bara to 130 bara, preferably at a pressure of 20 bara to 120 bara, in particular 40 to 110 bara.

[0172] Preferably, said monomer Mlb is added, into said reactor, in the form of an aqueous solution. According to a preferred embodiment, said monomer Mlb is added, into said reactor, continuously.

[0173] Said additive A2 is added before the initiation of the reaction when the pressure in said reactor is lower than the critical pressure of vinylidene fluoride. Alternatively, said additive A2 is added continuously into said reactor.

[0174] Said additive A2 is added in a mass content of 0.05% to 50% based on the total weight of fluorinated monomer Mla. The total weight of monomer Mla is that added over the entire polymerization step. Said additive A2 may be added in a mass content of 0.05 to 48% or 0.05 to 46% or 0.05 to 44% or 0.05 to 42% or 0.05 to 40% or 0.05 to 38% or 0.05 to 36% or 0.05 to 34% or 0.05 to 32% or 0.05 to 30% or 0.05 to 28% or 0.05 to 26% or 0.05 to 24% or 0.05 to 22% or 0.05 to 20% or 0.05 to 18% or 0.05 to 16% or 0.05 to 14% or 0.05 to 12% or 0.05 to 10% or 0.05 to 8% or 0.05 to 6% or 0.05 to 5%. Said additive A2 may be added in a mass content of 0.1 to 48% or 0.1 to 46% or 0.1 to 44% or 0.1 to 42% or 0.1 to 40% or 0.1 to 38% or 0.1 to 36% or from 0.1 to 34% or from 0.1 to 32% or from 0.1 to 30% or from 0.1 to 28% or from 0.1 to 26% or from 0.1 to 24% or from 0.1 to 22% or from 0.1 to 20% or from 0.1 to 18% or from 0.1 to 16% or from 0.1 to 14% or from 0.1 to 12% or from 0.1 to 10% or from 0.1 to 8% or from 0.1 to 6% or from 0.1 to 5%. Said additive A2 may be added in a mass content of 0.25 to 48% or 0.25 to 46% or 0.25 to 44% or 0.25 to 42% or 0.25 to 40% or 0.25 to 38% or 0.25 to 36% or 0.25 to 34% or 0.25 to 32% or 0.25 to 30% or 0.25 to 28% or 0.25 to 26% or 0.25 to 24% or 0.25 to 22% or 0.25 to 20% or 0.25 to 18% or 0.25 to 16% or 0.25 to 14% or 0.25 to 12% or 0.25 to 10% or 0.25 to 8% or 0.25 to 6% or 0.25 to 5%. Said additive A2 can be added in a mass content of 0.5 to 48% or 0.5 to 46% or 0.5 to 44% or 0.5 to 42% or 0.5 to 40% or 0.5 to 38% or 0.5 to 36% or 0.5 to 34% or 0.5 to 32% or 0.5 to 30% or 0.5 to 28% or 0.5 to 26% or 0.5 to 24% or 0.5 to 22% or 0.5 to 20% or 0.5 to 18% or 0.5 to 16% or 0.5 to 14% or 0.5 to 12% or 0.5 to 10% or 0.5 to 8% or from 0.5 to 6% or from 0.5 to 5%.

[0175] Said process is preferably carried out in the presence of an initiator. The initiator may be one or a combination of several of the initiators known in the art to be useful in the dispersion polymerization of halogenated monomers. Suitable non-limiting classes of initiators include persulfate salts, peroxides, and redox systems. Examples of persulfate salts are sodium persulfate, potassium persulfate, or ammonium persulfate. The amount of persulfate salt added to the reaction mixture based on the total weight of monomer added to the reaction mixture is typically about 0.005 to about 1.0 wt. %. The initiator may comprise a redox system. By "redox system" is meant a system comprising an oxidizing agent, a reducing agent, and optionally a promoter acting as an electron transfer medium.The promoter is a component that, in different oxidation states, is capable of reacting with both the oxidant and the reducing agent, thereby accelerating the overall reaction. Oxidizing agents include, for example, persulfate salts; peroxides, such as hydrogen peroxide; hydroperoxides, such as tert-butyl hydroperoxide and cumene hydroperoxide; and oxidizing metal salts such as, for example, ferric sulfate and potassium permanganate. Examples of reducing agents include sodium formaldehyde sulfoxylate; sodium or potassium sulfite, bisulfite, or metabisulfite; ascorbic acid; oxalic acid; and reduced metal salts. Typical promoters include transition metal salts such as ferrous sulfate.In redox systems, the oxidizing agent and reducing agent are typically used in an amount of about 0.01 to about 0.5 wt.% based on the total weight of monomer added to the reaction mixture. The promoter, if used, is typically employed in an amount of about 0.005 to about 0.025 wt.% based on the total weight of monomer added to the reaction mixture. Preferably, the initiator is selected from organic peroxides which are useful include dialkyl peroxides, alkyl hydroperoxides, peroxyesters and peroxydicarbonates. A suitable example of a dialkyl peroxide is di-tert-butyl peroxide. Examples of suitable peroxy esters include tert-amyl peroxypivalate, tert-butyl peroxypivalate and succinic acid peroxide.Examples of suitable peroxydicarbonate initiators include di-n-propyl peroxydicarbonate (NPP) and diisopropyl peroxydicarbonate, which are typically added to the reaction mixture in an amount based on the total weight of monomer added to the reaction mixture of about 0.05 to about 2.5 wt. %.

[0176] Said method can be carried out in the presence of a phase transfer agent. This can be a dispersant. The dispersant can be polyvinyl alcohol (PVA) or a compound comprising a cellulose unit such as methylcellulose, hydroxypropyl ethylcellulose, carboxymethylcellulose. Said phase transfer agent may be a surfactant. For example, said surfactant comprises a polyethylene glycol segment and a polypropylene glycol segment. Preferably, said surfactant has an HLB value of 1 to 20, in particular an HLB value of 1 to 5 or 10 to 15. In particular, said surfactant comprising a polyethylene glycol segment and a polypropylene glycol segment, has an HLB value of 1 to 5 and a weight average molecular weight of 2500 to 10000 g.mol-1. Alternatively, said surfactant comprising a polyethylene glycol segment and a polypropylene glycol segment, has an HLB value of 10 to 15 and a weight average molecular weight of 500 to 2500 g.mol-1.

[0177] A paraffin antifoulant is optionally used in the polymerization. Any long-chain saturated hydrocarbon wax or oil may be used. The oil or wax is added to the reactor prior to fluoropolymer formation in an amount sufficient to minimize polymer adhesion to the reactor components. This amount is generally proportional to the interior surface area of ​​the reactor and may vary from about 1 to about 40 mg / cm2 of interior surface area of ​​the reactor. If a paraffin wax or hydrocarbon oil is used as the antifoulant, the amount used is generally about 5 mg / cm2 of interior surface area of ​​the reactor.

[0178] The polymerization reaction mixture may optionally contain a buffering agent to maintain a controlled pH during the polymerization reaction. The pH is generally controlled in the range of 3 to 8. The buffering agent may be added at the beginning, at different points or throughout the polymerization. Suitable exemplary buffering agents are phosphate buffers and acetate buffers, which are well known to those skilled in the art.

[0179] Molecular weight regulators, also known as chain transfer agents, may optionally be used to adjust the molecular weight profile of the product. They may be added in a single portion at the beginning of the reaction, gradually, or continuously throughout the reaction. The amount of molecular weight regulator added to the polymerization reaction is generally from about 0.05 to about 5% by weight, more generally from about 0.1 to about 2% by weight based on the total weight of monomer added to the reaction mixture. Oxygenated compounds such as alcohols, carbonates, ketones, esters, and ethers may serve as molecular weight regulators. Examples of suitable oxygenated compounds include isopropyl alcohol, acetone, ethyl acetate, and diethyl carbonate.Other classes of molecular weight regulators include halogenated compounds such as chlorocarbons, hydrochlorocarbons, hydrofluorocarbons, chlorofluorocarbons, and hydrochlorofluorocarbons. Particular examples of weight regulators . Halogenated molecular weight regulators include 1-fluoroethane, trichlorofluoromethane, and 1,1-dichloro-2,2,2-trifluoroethane. Certain hydrocarbons can be used as molecular weight regulators, such as hydrocarbons that contain two to five carbon atoms, with ethane and propane as particular examples.

[0180] The fluoropolymer PI obtained at the end of the reaction can be washed and dried to form a powder. Alternatively, the fluoropolymer PI obtained at the end of the reaction can be washed and used in the form of a latex.

[0181] Fluorinated polymer PI

[0182] The present invention allows the production of a fluoropolymer PI. In this, the mass content of repeating units derived from the monomer Mla is at least 50%, preferably at least 60%, more preferably at least 70%, in particular at least 80%, more particularly at least 90%, preferably at least 95%.

[0183] Preferably, when it contains it, said fluoropolymer PI comprises from 0.01% to 10%, preferably from 0.05% to 5%, in particular from 0.1% to 5% by weight of repeating units derived from said monomer M 1b as defined in the present application based on the total weight of said fluoropolymer PI.

[0184] Preferably, when it contains it, said fluoropolymer PI comprises from 1% to 40%, preferably from 1% to 30%, in particular from 2% to 20% by weight of repeating units derived from said monomer M le as defined in the present application based on the total weight of said polymer.

[0185] Said fluorinated polymer PI may comprise repeating units derived from a monomer Mla being vinylidene fluoride, repeating units derived from a monomer Mlb, repeating units derived from a monomer Ml c; said monomers Mlb and Ml c being as defined above in the proportions as defined above.

[0186] According to one embodiment, the average particle size of said fluorinated polymer PI is between 10 and 1000 nm. According to another embodiment, the average particle size is between 1 pm and 500 pm, preferably between 10 pm and 500 pm. The average particle size is determined by laser granulometry. A particle size analyzer of the Malvem INSITEC System type is used for the measurement. This is carried out in a dry process by laser diffraction on a powder with a focal length of 100 mm. The method can be implemented in a vertical reactor.

[0187] Use

[0188] Said additive A2 as described in the present application is used as an anti-fouling agent in a process for producing a fluoropolymer PI. Said fluoropolymer PI is as defined in the present application according to any one of the embodiments. It may therefore comprise repeating units derived from a monomer Mla and a monomer Mlb and optionally a monomer Mlc; said monomers Mla, Mlb or Mlc are as defined above. Said additive A2 can be used according to any of the embodiments described in the present application. Examples

[0189] Example 1

[0190] The reaction was carried out in a 3L high-pressure reactor. 1373 g of demineralized water and 30 g of a phase transfer agent (dispersant or surfactant) were introduced into the reactor followed by 1224 g of vinylidene fluoride. The pressure was increased. 1.84 g of di-n-propyl peroxydicarbonate (NPP) was introduced into the reactor. The reactor was then heated to 50°C. Demineralized water was introduced to increase the pressure. The reactor was stirred at 750 rpm and the pressure was kept constant by the continuous injection of an aqueous solution containing 12 g / L of acrylic acid and 4 g / L of polyacrylic acid. The reaction was stopped after 325 minutes by venting the reactor to atmospheric pressure. A total of 784 g of solution was injected during the polymerization. The product was finally washed and dried. 945g of dry powder was recovered, representing a conversion rate of around 77%.Acrylic acid incorporation was measured at 0.77 mol% relative to the VF2 unit by NMR. No reactor fouling was observed.

[0191] Example 2

[0192] Example 1 was reproduced with a 12 g / L solution of acrylic acid and 32 g / L of polyacrylic acid. 886 g of solution were injected in 395 minutes before degassing the reactor at atmospheric pressure. 900 g of dry product were recovered, representing a conversion rate of approximately 73%. No fouling of the reactor was observed.

[0193] Example 3

[0194] Example 2 was reproduced by introducing a 32 g / L solution of polyacrylic acid before the initiation of the reaction, i.e. when the pressure in the reactor is lower than the critical pressure of vinylidene fluoride. The injection of a 12 g / L solution of acrylic acid is carried out continuously as in Example 2. No fouling was observed.

[0195] Comparative example 1

[0196] Example 1 was reproduced with a 20 g / L solution of acrylic acid and without polyacrylic acid. 790 g of solution were injected over 280 minutes before degassing the reactor at atmospheric pressure. 1050 g of dry product were recovered, representing a conversion rate of approximately 86%. Block formation was observed and the reactor was heavily fouled.

Claims

1. Claims A process for producing a fluorinated polymer PI comprising a step of polymerizing, in a reactor, a fluorinated monomer Mla and a monomer Mlb in the presence of an initiator and from 0.05% to 50% by weight of an additive A2 based on the total weight of fluorinated monomer Mla; said additive A2 comprising repeating units derived from a monomer M 2 ; said monomer Mlb and said monomer M2 are independently of each other of formula (I), (II), (III), (IV), (V), (VI) or (VII) or a mixture thereof R1R2C=C(R3)((X2)PC(O)R4) (I) R5R6C=C(R7)(OC(O)R8) (II) R9R1 °C=CR11C(O)OC(O)CR12=CR13R14 (III) R30R31C=CR32(CN) (VI) r33r34C=CR35(C(O)NR36R37) (VII) in which R1, R2 and R3 are independently selected from the group consisting of H, CO2H and C1-C5 alkyl; R4 is selected from the group consisting of -NHC(CH3)2CH2 C(O)CH3 and -OR25 with R25 selected from the group consisting of H and C1-C18 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO2H, SO3H, -OPO32, -C(O)OR25, -OC(O)R25, and a five or six membered heterocycle comprising at least one nitrogen atom in its ring chain; R25 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted with one or more CO2 H functional groups; X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wr and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2 H or ester group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R26, R27, R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and Cr C5 alkyl; p' is 0 or 1; R5, R6 and R7 are independently of each other selected from the group consisting of H and Ci-C5 alkyl; R8 is CrC5 alkyl; R9 R10 R11 R12 R13 R14 R15 R16 R17 R18 R19 R20 R21 R22 R23 R24 , R30, R31, R32, R33, R34, R35are independently of each other selected from the group consisting of H and Ci-C5 alkyl, preferably selected from the group consisting of H and CH3; R36 and R37 are, independently of each other, selected from the group consisting of H and Ci-Cio alkyl optionally substituted by one or more groups -OH, -CO2H, SO3 H, -OPO32, -C(O)OR38, -OC(O)R38;R38 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted with one or more CO2H functional groups.;

2. Process according to the preceding claim characterized in that said monomer Ml b is of formula R1R2C=C(R3)((X2)PC(O)R4) in which the substituents R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and Ci-C5 alkyl; R4 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 or -OR25 with R25 selected from the group consisting of H and CrCi8 alkyl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H, -OC(O)R25, -C(O)O-R25 or a five- or ten-membered heterocycle comprising at least one nitrogen atom in its cyclic chain; R25 being selected from the group consisting of C1-C6 alkyl or C6-C12 aryl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H; p' is 0 or 1;X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]W r and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being; an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R26, R27, R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and C1-C5 alkyl.

3. Process according to any one of the preceding claims, characterized in that said monomer Ml b is added, into said reactor, in the form of an aqueous solution and continuously.

4. Method according to any one of the preceding claims, characterized in that said additive A 2 is water-soluble.

5. A method according to any one of the preceding claims characterized in that said fluorinated monomer Mla selected from the group consisting of vinyl fluoride; vinylidene fluoride (VDF); trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) and perfluoro(propyl vinyl) ether (PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2=CFOCF2CF2SO2F; the product of formula F(CF2 )nCH2OCF=CF2 in which n is 1, 2, 3, 4 or 5; the product of formula R1CH2OCF=CF2 in which R1 is hydrogen or F(CF2 )m and m is 1, 2, 3 or 4; the product of formula R2OCF=CH2 in which R2 is F(CF2)p and p is 1, 2, 3 or 4;perfluorobutylethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-l-propene or a mixture thereof.;

6. Process according to any one of the preceding claims, characterized in that said monomer Mla is vinylidene fluoride.

7. Process according to the preceding claim characterized in that said additive A2 is added before the initiation of the reaction when the pressure in said reactor is lower than the critical pressure of vinylidene fluoride or said additive A2 is added continuously in said reactor.

8. A process according to any one of the preceding claims characterized in that said monomer M1 b is of formula R*R2 C=C(R3)((X2)pC(O)R4) in which the substituents R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and C1-C3 alkyl; R4 is -OR25 with R25 selected from the group consisting of H and C1-C10 alkyl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H, -OC(O)R25, -C(O)O-R25; R25 being selected from the group consisting of C1-C5 alkyl or C6 aryl optionally substituted by one or more groups -OH, -CO2H, -SO3H, -PO3H; p' is 0 or 1; X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]W r and a C1-C5 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2H or ester group(s); with wl being 26 27 28 29 an integer from 1 to 5; R , Rz', R. R are independently of each other, independently for each wl unit, selected from the group consisting of H and Ci-C3 alkyl.

9. A method according to any one of the preceding claims, characterized in that said additive A 2 comprises repeating units derived from a monomer M 2 of formula (I), (II), (VI), (VII) or a mixture thereof R1R2C=C(R3)((X2)PC(O)R4) (I) R5R6C=C(R7)(OC(O)R8) (II) R30R31C=CR32(CN) (VI) r33r34C=CR35(C(O)NR36R37) (VII) in which R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and Ci-C5 alkyl; R4 is selected from the group consisting of -NHC(CH3)2CH2 C(O)CH3 and -OR25 with R25 selected from the group consisting of H and C1-C18 alkyl optionally substituted with one or more group(s) selected from the group consisting of -OH, -CO 2H, -SO3H, -OPO32, -C(O)OR25, -OC(O)R25, and a five or six membered heterocycle comprising at least one nitrogen atom in its ring chain; R25 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted with one or more CO2 H functional groups; X2 is selected from the group consisting of -[-C(O)OC(R26)(R27)C(R28)(R29)-]wi- and a C1-C10 alkyl hydrocarbon group optionally carrying one or more -OH, -CO2 H or ester group(s); with wl being an integer from 1 to 50, advantageously from 1 to 25, preferably from 1 to 10, in particular from 1 to 5; R26, R27, R28, R29 are independently of each other, independently for each wl unit, selected from the group consisting of H and Cr C5 alkyl; p' is 0 or 1; R5, R6 and R7 are independently of each other selected from the group consisting of H and C1-C5 alkyl; R8 is C1-C5 alkyl; R30, R31, R32, R33, R34, R35 are independently of each other selected from the group consisting of H and C1-C5 alkyl, preferably selected from the group consisting of H and CH3;R36 and R37 are, independently of each other, selected from the group consisting of H and C1-C10 alkyl optionally substituted by one or more -OH, -CO2H, SO3 H, -OPO32, -C(O)OR38, -OC(O)R38 groups; R38 is selected from the group consisting of C1-C5 alkyl and C6-C12 aryl substituted by one or more CO2H functional groups.;

10. A method according to any one of the preceding claims characterized in that said additive A2 comprises repeating units derived from a monomer M 2 of formula R'R2C=C(R3)(C(O)R4) (I) in which R1, R2 and R3 are independently of each other selected from the group consisting of H, CO2H and Ci-C3 alkyl; R4 is -OR25 with R25 selected from the group consisting of H and Ci-C5 alkyl optionally substituted by one or more group(s) selected from the group consisting of -OH, -CO2 H, -SO3H, -OPO32, -C(O)OR25, -OC(O)R25; R25 is selected from the group consisting of C1-C5 alkyl and C6 aryl substituted with one or more CO2H functional groups.

11. Use of an additive A2 as defined in any one of claims 1, 5, 9 or 10 as an antifouling agent in a process for producing a fluoropolymer PI.

12. Use according to the preceding claim characterized in that said fluoropolymer PI comprises repeating units derived from a fluorinated monomer Mla selected from the group consisting of vinyl fluoride; vinylidene fluoride (VDF); trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether (PMVE), perfluoro(ethyl vinyl) ether (PEVE) and perfluoro(propyl vinyl) ether (PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); the product of formula CF2=CFOCF2CF(CF3)OCF2CF2X in which X is SO2F, CO2 H, CH2OH, CH2OCN or CH2OPO3H; the product of formula CF2 =CFOCF2CF2SO2F; the product of formula F(CF2)nCH2OCF=CF 2 in which n is 1, 2, 3, 4 or 5; the product of formula R'CH2 OCF=CF2 in which R1 is hydrogen or F(CF2)m and m is 1, 2, 3 or 4;the product of formula R2OCF=CH2 in which R2 is F(CF2)p and p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); trifluoropropene, tetrafluoropropene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, bromotrifluoroethylene, chlorofluoroethylene, chlorotrifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-l-propene or a mixture thereof.;

13. Use according to any one of the preceding claims 11 or 12 characterized in that said fluorinated polymer PI comprises repeating units derived from a fluorinated monomer Mla being vinylidene fluoride.

14. Use according to the preceding claim, characterized in that said fluorinated polymer PI also comprises repeating units derived from a monomer Mlb as defined in claim 1, 2 or Q

15. o. Use according to the preceding claim, characterized in that said fluorinated polymer PI also comprises repeating units derived from a monomer Mlb of formula R'R2C=C(R3)(C(O)R4) in wherein the substituents R1, R2 and R3 are independently selected from the group consisting of H, CO2H and C1-C3 alkyl; R4 is -OR25 with R25 selected from the group consisting of H and C1-C10 alkyl optionally substituted with one or more groups -OH, -CO2H, -SO3H, -PO3H, -OC(O)R25, -C(O)O-; Rd” being selected from the group consisting of Cr C5 alkyl or C6 aryl optionally substituted with one or more groups -OH, -CO2H, -SO3H, -PO3H.