Functional fluoropolymers

Abstract

To provide a fluorinated copolymer comprising a fluorinated vinylic monomer and a hydrophilic comonomer.SOLUTION: The invention relates to novel linear, semi-crystalline, functional fluoropolymers that have been obtained by copolymerizing a fluorinated vinylic monomer and a hydrophilic monomer chosen from vinyl alkyl acids, vinyl phosphonates, functional acrylamides, carbonates, vinyl ethers, alkoxy compounds, and double hydrophilic group monomers.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to novel linear semi-crystalline functional fluoropolymers obtained by copolymerizing fluorinated vinyl monomers with one or more hydrophilic comonomers. The comonomers may optionally have halogen functionality. In the copolymers, up to 10.0% by weight of the comonomer units are present as single monomer units among two fluoromonomer units. The present invention also relates to a method for producing the fluoromonomer / comonomer copolymers. The functional fluoropolymers provide enhanced properties compared to the fluoropolymers alone, such as enhanced adhesion and hydrophilic characteristics. The fluoropolymers of the present invention can be used in applications that benefit from functional fluoropolymers, such as binders in electrode and separator compositions, or in the formation of hydrophilic membranes and hollow fibers. [Background technology]

[0002] Fluoropolymers are traditionally used in applications that require special properties such as low surface energy, high resistance to chemical attack, aging resistance, electrochemical stability, etc. However, these advantageous properties also make fluoropolymers difficult to handle, limiting their use. For example, the lack of functional groups on fluoropolymers makes it difficult to attach them to substrates, promote crosslinking, provide sites for subsequent chemical modification, be wetted by water, or impart hydrophilic characteristics. There is a need for fluorinated polymers with modified properties (such as functional groups) that can enhance their properties.

[0003] However, it is difficult to directly add functional monomer units into the backbone of polymerizing polymer, especially in a random manner, due to the aggressive nature of fluorine-containing free radicals.Functional groups have been added by several means, such as direct copolymerization of functional monomers with fluoromonomers and post-polymerization grafting mechanisms.For example, KYNAR® ADX resin available from Arkema is produced by grafting maleic anhydride onto polyvinylidene fluoride homopolymer or copolymer, as described in US Pat. No. 7,241,817.Furthermore, WO2013 / 110740 and US Pat. No. 7,351,498 describe the functionalization of fluoropolymers by monomer grafting or copolymerization.

[0004] U.S. Pat. No. 5,415,958 describes the copolymerization of vinylidene fluoride with unsaturated dibasic acid monoester polar monomers to improve the adhesion of PVDF to various substrates by introducing carbonyl groups into the PVDF backbone.

[0005] US Pat. No. 8,337,725 discloses copolymerization of vinylidene fluoride with at least one hydrophilic (meth)acrylic monomer of the formula: [ka] Here, R1, R2, and R3 may be the same or different and are independently a hydrogen atom or a C1-C3 hydrocarbon group; R OH is hydrogen or a C1-C5 hydrocarbon moiety containing at least one hydroxyl group. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent No. 7,241,817 [Patent Document 2] International Publication No. WO2013 / 110740 [Patent Document 3] U.S. Patent No. 7,351,498 [Patent Document 4] U.S. Pat. No. 5,415,958 [Patent Document 5] U.S. Patent No. 8,337,725 Summary of the Invention [Problem to be solved by the invention]

[0007] There is a need to further improve the adhesion performance of fluorinated polymers.

[0008] The discovery that copolymerization of a fluorinated vinyl monomer with a hydrophilic comonomer, optionally having halogen functionality, results in a functionalized fluoropolymer that can improve adhesion to substrates compared to non-functionalized fluoropolymers while maintaining good mechanical and thermal properties, was not present in the art. [Means for solving the problem]

[0009] The present invention relates to fluorinated copolymers comprising vinylic monomers and hydrophilic monomers.

[0010] The present invention further relates to a formulation comprising a fluorinated copolymer in a solvent, and optionally further comprising activated carbon and metal particles selected from the group consisting of lithium iron phosphate (LFP), lithium nickel manganese cobalt oxide (NMC), lithium manganese cobalt oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide, and lithium nickel manganese spinel.

[0011] The present invention further provides a process for producing a fluorinated copolymer in an aqueous reaction medium, comprising the steps of: a) forming an aqueous emulsion comprising at least one initiator, a stabilizer, at least one fluoromonomer, and a hydrophilic monomer; b) initiating copolymerization of the at least one fluoromonomer with the hydrophilic monomer under heat and pressure with stirring: Also contemplated is the method comprising:

[0012] The invention further relates to articles formed from said fluorinated copolymers that benefit from the special properties of said functionalized copolymers. These articles are useful in applications such as electrodes or separators for batteries or capacitors, hydrophilic porous or hollow fiber membranes, articles coated on at least one side with said functionalized fluoropolymers, impregnation of woven and nonwoven fibers, and multi-layer constructions in which said functionalized fluoropolymer forms a tie layer between a fluoropolymer layer and a polymer layer that is incompatible with the fluoropolymer layer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Fluoropolymers, especially poly(vinylidene fluoride) (PVDF) and its copolymers, find application as binders in electrode articles used in lithium-ion batteries. As the demand for higher battery performance increases, there is an increasing need to reduce the binder content in the electrodes. To reduce the binder content, it is of utmost importance to improve the performance of the binder material. The initial performance is determined by an adhesion test, according to which the compounded electrodes are subjected to a peel test. Improvements in this test lead to improved binding performance and the possibility to reduce the overall binder loading, increase the active material loading, and improve the battery capacity. Copolymers of fluorinated vinyl monomers and acid-functional comonomers have been shown to provide this type of improved adhesion performance. These approaches also suffer from low reaction productivity and the difficulty of supplying sufficient amounts of material to the rapidly growing market. Here, we present new copolymers and methods with greatly improved productivity (i.e., reduced polymerization time).

[0014] The present invention solves the above problems by providing a fluorinated copolymer comprising a fluorinated vinylic monomer and a hydrophilic comonomer.

[0015] The fluorinated vinyl monomer is selected from the group including: vinylidene fluoride (VDF), tetrafluoroethylene (TFE), trifluoroethylene (TrFE), chlorotrifluoroethylene (CTFE), hexafluoropropene (HFP), vinyl fluoride (VF), hexafluoroisobutylene (HFIB), perfluorobutylethylene (PFBE), pentafluoropropene, 3,3,3-trifluoro-1-propene, 2-trifluoromethyl-3,3,3-trifluoropropene, 2,3,3,3-tetrafluoropropene, fluorinated vinyl ethers such as perfluoromethyl ether (PMVE), perfluoroethyl vinyl ether (PEVE), perfluoropropyl vinyl ether (PPVE), perfluorobutyl vinyl ether (PBVE), long chain alkyl perfluorinated vinyl ethers, fluorinated dioxoles, C4 and higher moieties or perfluorinated α-olefins, C3 and higher moieties or perfluorinated cyclic alkenes, and combinations thereof.

[0016] The hydrophilic comonomers are selected from vinyl alkyl acids, vinyl phosphonates, functional acrylamides, carbonates, vinyl ethers, allyloxy compounds, and vinyl or allyl dual hydrophilic group monomers, and combinations thereof.

[0017] The functional copolymers according to the present invention are further characterized by the following embodiments.

[0018] According to one embodiment, the fluorinated copolymer comprises 0.01-10.0% by weight of one or more hydrophilic monomers and 90.0-99.99% by weight of a fluorinated vinyl-based monomer.

[0019] According to one embodiment, the fluorinated copolymer comprises vinylidene fluoride and one or more hydrophilic monomers.

[0020] According to one embodiment, the fluorinated copolymer comprises vinylidene fluoride and one or more hydrophilic monomers containing at least one halogen atom on at least one of the vinyl carbons.

[0021] According to one embodiment, the hydrophilic monomer contains at least one fluorine atom on at least one of the vinyl carbons.

[0022] The invention further relates to a formulation comprising a fluorinated copolymer in a solvent, preferably chosen from N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), triethylphosphite (TEP), acetone, tetrahydrofuran, methyl ethyl ketone (MEK), methyl isobutyl ketone (MiBK), ethyl acetate (EA), butyl acetate (BA), dimethyl carbonate (DMC), diethyl carbonate (DEC) or methyl ethyl carbonate (MEC).

[0023] According to one embodiment, the formulation further comprises activated carbon and lithium salt particles suspended in the solvent. The lithium salt particles are selected from the group of lithium iron phosphate (LFP), lithium nickel manganese cobalt oxide (NMC), lithium cobalt oxide (LCO), lithium manganese oxide (LMO), lithium nickel-cobalt-aluminum oxide (NCA) and lithium-nickel-manganese oxide (LNMO). Such formulations are particularly suitable for forming battery electrode films, particularly positive electrodes for lithium-ion batteries. The invention encompasses batteries comprising the fluorinated copolymers described herein.

[0024] The present invention further contemplates a process for preparing a fluorinated copolymer in an aqueous reaction medium, the process comprising: a) forming an aqueous emulsion comprising at least one initiator, a stabilizer, at least one fluorinated vinyl monomer, and said hydrophilic monomer; b) initiating copolymerization of the at least one fluorinated vinyl monomer with the hydrophilic monomer under heat and pressure with stirring; This includes:

[0025] The polymerization reaction according to the present invention can be carried out by charging a reactor with water (preferably deionized water), at least one fluorinated vinyl monomer, at least one of said hydrophilic monomers and optionally one or more surfactants, chain transfer agents and / or antifouling agents. The reactor may be purged of air before the introduction of the monomers. Water is added before bringing the reactor to the desired starting temperature, while other materials may be added before or after bringing the reactor to that temperature. At least one radical initiator is added to initiate and sustain the polymerization reaction. Additional monomer may be optionally added to replenish consumed monomer, and other materials may be optionally added as the polymerization proceeds to sustain the reaction and adjust the properties of the final product.

[0026] "Copolymer" is used to mean a polymer having two or more different monomer units. "Polymer" is used to mean both homopolymers and copolymers. The polymers can be linear, branched, star, comb, block or any other structure. The polymers may have a homogeneous, heterogeneous or gradient distribution of the comonomer units. All references cited are incorporated herein by reference. As used herein, percentages mean weight percent unless otherwise specified. Unless otherwise specified, molecular weights are weight average molecular weights measured by GPC using polymethyl methacrylate as standard. If the polymer contains some crosslinking and GPC cannot be applied due to insoluble polymer fractions, the molecular weight of the soluble / gel fraction or the soluble fraction after extraction from the gel is used. Crystallinity and melting temperature are measured by DSC as described in ASTM method D3418 at a heating rate of 10°C / min. Melt viscosity is measured at 230°C according to ASTM method D3835, kilopoise @ 100 seconds -1 It is expressed as:

[0027] Hydrophilic Monomers The hydrophilic comonomers used in combination with one or more fluoromonomers include, but are not limited to, one or more of the following, with mixtures of more than one monomer in a particular class, as well as mixtures of two or more monomers from the various classes below blended together to produce terpolymers:

[0028] A) as comonomer (M1), a vinyl alkyl acid having the formula [ka] Where: R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I); R4 is C1~C 16 Linear, branched, aryl or cyclic alkyl groups, C1-C 16 fluorinated linear, branched, aryl or cyclic alkyl groups, oligomers of hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide, R5 is a carboxylic acid (C(O)OH), an alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - NH4 + ), alkyl ammonium carboxylates (COO - N(Alk)4 + ), alcohols (OH), amides (C(O)NH2), dialkylamides (C(O)NAlk2), sulfonic acids (S(O)(O)OH), and alkali metal sulfonates (S(O)(O)O - M + ), sulfonic acid ammonium salt (S(O)(O)O - NH4 + ), sulfonic acid alkyl ammonium salts (S(O)(O)O - N(Alk)4 + ).

[0029] B) a vinyl alkyl acid having the formula M2: [ka] Where: R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I); R4 and R5 are independently hydrogen, C1-C 16 Linear alkyl, branched alkyl, aryl or cyclic alkyl group, C1-C 16 Fluorinated linear alkyl, branched alkyl, aryl or cyclic alkyl groups, oligomers of hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide, alkali metal ions (Li + , Na + , K + , Rb + , Cs + ), ammonium ion (NH4 + ) or alkylammonium (NAlk4 + ).

[0030] C) Functionalized acrylamide as comonomer (M3) having the formula [ka] Where: R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I); R4 and R6 are independently hydrogen, C1-C 16 Linear, branched, aryl or cyclic alkyl groups, C1-C 16 fluorinated linear, branched, aryl or cyclic alkyl groups, oligomers of hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide, R5 and R7 are each independently a carboxylic acid (C(O)OH), an alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - NH4 + ), alkyl ammonium carboxylates (COO - N(Alk)4 +), alcohols (OH), amides (C(O)NH2), dialkylamides (C(O)NAlk2), sulfonic acids (S(O)(O)OH), alkali metal sulfonates (S(O)(O)O - M + ), ammonium sulfonate (S(O)(O)O - NH4 + ), sulfonic acid alkyl ammonium salts (S(O)(O)O - N(Alk)4 + ), ketones (C(O)) or acetylacetonates (C(O)-CH2-C(O)), or phosphonates (P(O)(OH)2), alkali metal or ammonium phosphonates.

[0031] D) Carbonates containing comonomer M4 [ka] Where: R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I); R4 is a bond, C1~C 16 Linear alkyl, branched alkyl, aryl or cyclic alkyl group, C1-C 16 a fluorinated linear alkyl, branched alkyl, or aryl or cyclic alkyl group; R5 is a C1-C cyclic ring structure that contains a carbonate group. 16 Cyclic alkyl group or C1-C 16 It is a fluorinated cyclic alkyl group.

[0032] E) as comonomer (M5) vinyl ether having the formula [ka] Where: R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I); R4 is C1~C 16 Linear, branched, aryl or cyclic alkyl groups, C1-C 16fluorinated linear, branched, aryl or cyclic alkyl groups, oligomers of hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide, R5 is a carboxylic acid (C(O)OH), an alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - NH4 + ), alkyl ammonium carboxylates (COO - N(Alk)4 + ), alcohols (OH), amides (C(O)NH2), dialkylamides (C(O)NAlk2), sulfonic acids (S(O)(O)OH), and alkali metal sulfonates (S(O)(O)O - M + ), sulfonic acid ammonium salt (S(O)(O)O - NH4 + ), sulfonic acid alkyl ammonium salts (S(O)(O)O - N(Alk)4 + ), ketone (C(O)) or acetylacetonate (C(O)-CH2-C(O)).

[0033] F) as comonomer (M6) an allyloxy compound having the formula [ka] Where: R1, R2 and R3 are hydrogen or halogen (F, Cl, Br, I); R4 is CH2 or CF2; R5 is C1~C 16 Linear, branched, aryl or cyclic alkyl groups, C1-C 16 fluorinated linear, branched, aryl or cyclic alkyl groups, oligomers of hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide, R6 is a carboxylic acid (C(O)OH), an alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - NH4+ ), alkyl ammonium carboxylates (COO - N(Alk)4 + ), alcohols (OH), amides (C(O)NH2), dialkylamides (C(O)NAlk2), sulfonic acids (S(O)(O)OH), alkali metal sulfonates (S(O)(O)O - M + ), ammonium sulfonate (S(O)(O)O - NH4 + ), sulfonic acid alkyl ammonium salts (S(O)(O)O - N(Alk)4 + ), ketones (C(O)) or acetylacetonates (C(O)-CH2-C(O)), or phosphonates (P(O)(OH)2), alkali metal or ammonium phosphonates.

[0034] G) Multiple hydrophilic group comonomers

[0035] Monomers having two or more hydrophilic groups are also contemplated by the present invention, including, but not limited to, itaconic acid, maleic acid, glutaconic acid, fumaric acid, and the anhydrides, alkali metal salts, ammonium salts, and mono-, di-, tri-, and tetraalkylammonium salts thereof.

[0036] The hydrophilic comonomer can be used in the reactor in an amount of, for example, about 0.01 to about 15% by weight based on the total monomers, and is preferably used in an amount of about 0.01 to about 5% by weight based on the total monomers. In various embodiments, the total amount of hydrophilic monomer is at least 0.01, at least 0.05, at least 0.1, at least 1.0, or at least 2.0% by weight based on the total monomers. In other embodiments, the total amount of hydrophilic monomer is 13.0% by weight or less, 10.0% by weight or less, 9.0% by weight or less, 7.0% by weight or less, 6.0% by weight or less, or 5.0% by weight or less based on the total monomers. For convenience of handling, the hydrophilic comonomer can be used in the form of a solution, such as an aqueous solution.

[0037] The polymer may contain 0.01 to 15.0% by weight of the hydrophilic monomer and 85.0 to 99.99% by weight of the fluorinated vinyl monomer.

[0038] Surfactants The surfactant used in the polymerization can be any surfactant known in the art to be useful in PVDF emulsion polymerization, including perfluorinated surfactants, partially fluorinated surfactants, and non-fluorinated surfactants. In a preferred embodiment, the PVDF emulsion of the present disclosure can be fluorosurfactant-free, and no fluorosurfactant is used in any part of the polymerization. Non-fluorinated surfactants useful in PVDF polymerization can be both ionic and non-ionic, and include, but are not limited to, 3-allyloxy-2-hydroxy-1-propanesulfonate, polyvinylphosphonic acid, polyacrylic acid, polyvinylsulfonic acid and their salts, polyethylene glycol and / or polypropylene glycol and their block copolymers, alkylphosphonates, and siloxane-based surfactants.

[0039] Surfactants can also be used in combination with the hydrophilic comonomers to provide additional stability to the polymer emulsion. Preferred surfactants are non-fluorinated hydrocarbon surfactants, siloxane surfactants, or combinations thereof. For example, hydrophilic (meth)acrylic comonomers can be used in combination with sodium dodecylbenzenesulfonate (SDDBS), sodium octyl sulfonate, sodium lauryl sulfate, ammonium lauryl sulfate, sodium laureth sulfate, and others. In some embodiments of the present invention, no fluorosurfactant is present in the aqueous emulsion and / or no fluorosurfactant is introduced during copolymerization of the fluorinated vinyl monomer and the hydrophilic (meth)acrylic comonomer. In one embodiment, the stabilizer is a polyelectrolyte. In another embodiment, the stabilizer of the polymer emulsion is a functionalized cellulose.

[0040] Initiator The terms "initiator" and "radical initiator" and "free radical initiator" refer to chemicals that can provide a source of free radicals, either spontaneously or induced by exposure to heat or light. Examples of suitable initiators include peroxides, peroxydicarbonates, and azo compounds. "Initiators" also include redox systems that are useful for providing a source of free radicals. The terms "radical" and "free radical" refer to chemical species that contain at least one unpaired electron.

[0041] The radical initiator is added to the reaction mixture in an amount sufficient to initiate and maintain the polymerization reaction at the desired reaction rate. The order of addition can vary depending on the desired process and latex emulsion characteristics.

[0042] The radical initiator can include a persulfate, such as sodium persulfate, potassium persulfate, or ammonium persulfate. The amount of persulfate added to the reaction mixture can be, for example, about 0.002 to about 1.0 weight percent (based on the total amount of monomers added to the reaction mixture).

[0043] The radical initiator may include organic peroxides, such as alkyl, dialkyl or diacyl peroxides, peroxydicarbonates and peroxyesters or mixtures thereof. A preferred dialkyl peroxide is di-t-butyl peroxide (DTBP), which may be added to the reaction mixture in an amount of about 0.01 to about 5% by weight based on total monomers, and preferably in an amount of about 0.05 to about 2.5% by weight based on total monomers. Preferred peroxydicarbonate initiators are di-n-propyl peroxydicarbonate and diisopropyl peroxydicarbonate, which may be added to the reaction mixture in an amount of about 0.5 to about 2.5% by weight based on total monomers. Peroxyester initiators include t-amyl peroxypivalate, t-butyl peroxypivalate and succinic acid peroxide.

[0044] The radical initiator can include an azo initiator, such as 2,2'-azobis(2-methylpropionamidine) dihydrochloride.

[0045] The radical initiator may include a redox system. By "redox system" is meant a system that includes an oxidizing agent, a reducing agent, and optionally an accelerator as an electron transfer medium. The oxidizing agents include, for example, persulfates; peroxides such as hydrogen peroxide; hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide; and oxidizing metal salts such as ferric sulfate. The reducing agents include, for example, sodium formaldehyde sulfoxylate, sodium sulfite, potassium sulfite, ascorbic acid, bisulfite, metabisulfite, and reduced metal salts. The accelerator is a component of the redox system that can accelerate the overall reaction by reacting with both the oxidizing agent and the reducing agent in various oxidation states. The accelerator includes, for example, transition metal salts such as ferrous sulfate. In the redox system, the oxidizing agent and the reducing agent can be used in an amount of about 0.01 to about 0.5% by weight based on the total monomer. The optional accelerator can be used in an amount of about 0.005 to about 0.025% by weight based on the total monomer. Redox systems are described in GS Misra and UDN Bajpai, Prog. Polym. Sci., 1982, 8(1-2), pp. 61-131.

[0046] Chain Transfer Agents Chain transfer agents are added to the polymerization to control the molecular weight of the product. They may be added to the polymerization at a single location at the beginning of the reaction or may be added to the polymerization incrementally or continuously throughout the reaction. The amount and method of addition of the chain transfer agent depends on the activity of the chain transfer agent used and the molecular weight desired for the polymer product. The amount of chain transfer agent added to the polymerization reaction is preferably from about 0.05 to about 5 weight percent, and even more preferably from about 0.1 to about 2 weight percent, based on the total weight of monomers added to the reaction mixture.

[0047] Oxygen-containing compounds such as alcohols, carbonates, ketones, esters and ethers can act as chain transfer agents. Examples of oxygen-containing compounds useful as chain transfer agents include isopropyl alcohol, as described in U.S. Pat. No. 4,360,652. Another class of compounds that can act as chain transfer agents in the polymerization of halogen-containing monomers includes halocarbons, such as chlorocarbons, and hydrohalocarbons. Alkanes such as ethane and propane can also act as chain transfer agents.

[0048] Buffer The polymerization reaction mixture may optionally contain a buffer to maintain a controlled pH throughout the polymerization reaction. The pH is preferably controlled within the range of about 4 to about 8 to minimize undesirable color development in the product.

[0049] The buffer is an organic or inorganic acid or an alkali metal salt thereof, or a base or a salt of such an organic or inorganic acid, and has at least one pK in the range of about 4 to about 10, preferably about 4.5 to about 9.5. a value and / or pK b The term "acid buffer" includes those having a value of 0.01 to 0.015. Preferred buffers for the practice of the present invention include, for example, phosphate buffers and acetate buffers. A "phosphate buffer" is a salt or mixture of salts of phosphoric acid. An "acetate buffer" is a salt of acetic acid.

[0050] When potassium persulfate is used as the radical initiator, it is preferred to use a buffer. A preferred buffer for use with a persulfate radical initiator is sodium acetate. A preferred amount of sodium acetate buffer is about 50% to about 150% by weight based on the weight of persulfate initiator added to the reaction. In one preferred embodiment, the initiator feed comprises about equal weights of potassium persulfate and sodium acetate in an aqueous solution.

[0051] Antifouling agent Paraffin wax or hydrocarbon oil, when added to the reaction, acts as an antifouling agent to minimize or prevent polymer deposits on the reactor parts. Any long chain saturated hydrocarbon wax or oil can perform this function. The amount of oil or wax added to the reactor is that amount which serves to minimize the formation of polymer deposits on the reactor parts. This amount is generally proportional to the internal surface area of ​​the reactor, with 1 cm of internal reactor surface area serving as an antifouling agent. 2 The amount of paraffin wax or hydrocarbon oil can vary from about 1 to about 40 mg per cm of reactor surface area. 2 Preferably, the dosage is about 5 mg per serving.

[0052] Copolymerization conditions The temperature employed for the polymerization can vary depending on the initiator system selected, for example from 20 to 130° C. This polymerization temperature is preferably from 35 to 130° C., particularly preferably from 70 to 125° C.

[0053] The pressure employed for the polymerization can vary from 280 to 20000 kPa, depending on the reactor volume, the initiator system selected and the choice of monomers. The polymerization pressure is preferably between 2000 and 11000 kPa, particularly preferably between 2750 and 6900 kPa.

[0054] The polymerization is carried out under stirring or other agitation. The stirring / agitation can be constant or can be varied as the polymerization progresses to optimize process conditions. In one embodiment, both multiple stirring speed settings and multiple temperature settings are employed to control the reaction.

[0055] According to one embodiment of the process of the present invention, a pressurized polymerization reactor equipped with an agitator and heat control means is charged with water, preferably deionized water, one or more halogenated monomers (1) and at least one fluorinated vinyl monomer, which mixture may optionally contain one or more surfactants, buffers, antifouling agents or chain transfer agents for molecular weight control of the polymer product.

[0056] Prior to introducing the monomer(s), it is preferred to remove air from the reactor in order to provide an oxygen-free environment for the polymerization reaction.

[0057] The order of addition of the polymerization ingredients can vary, but it is generally preferred to have at least a portion of the hydrophilic monomer present in the aqueous reaction medium before polymerization of the fluorinated vinyl monomer is initiated. Additional hydrophilic monomer can be fed to the reactor during the reaction.

[0058] In one embodiment, water, initiator, hydrophilic monomer and optional surfactants, antifoulants, chain transfer agents and / or buffers are charged to a reactor, the reactor is heated to the desired reaction temperature, and then fluorinated vinyl monomer is fed to the reactor, preferably at a rate that results in an essentially constant pressure.

[0059] Alternatively, the fluorinated vinyl monomer, hydrophilic monomer and initiator can be fed to the reactor along with one or more optional ingredients. Other variations on the fluoropolymer copolymerization process as known in the art are also contemplated.

[0060] Once the desired weight of monomer has been fed to the reactor, the monomer feed is stopped. Optionally, additional radical initiator is added and the reaction is allowed to run for a suitable period of time to complete the reaction. As the monomer in the reactor is consumed, the pressure drops.

[0061] Once the copolymerization reaction is complete, the reactor is brought to ambient temperature and the residual unreacted monomers are vented to atmospheric pressure. The aqueous reaction medium containing the copolymer is then recovered from the reactor as a latex, which consists of a stable mixture of the reaction components, namely water, hydrophilic monomers, initiator (and / or initiator decomposition products) and copolymer solids.

[0062] Generally, the latex contains from about 10 to about 50 weight percent copolymer solids. The polymer in the latex can be in the form of small particles having sizes ranging from about 30 nm to about 800 nm.

[0063] Product handling The product of the copolymerization is a latex, which can be used in that form, usually after filtering the solid by-products from the polymerization process, or can be coagulated to isolate the solids, which can then be washed and dried. For use in the form of a latex, the latex can be stabilized by adding a surfactant, which can be the same or different from the surfactant present during polymerization (if used). The subsequently added surfactant can be, for example, an ionic or non-ionic surfactant. In one embodiment of the invention, no fluorosurfactant is added to the latex. For solid products, the latex can be coagulated mechanically or by adding salt or acid, and then isolated by well known means such as filtration. Once isolated, the solid product can be purified by washing or other techniques and dried for use as a powder, which can also be further processed into granules or pellets.

[0064] In one embodiment, the functional copolymer according to the invention is applied to the substrate as a latex in water or as a solvent solution, the solvent being selected from those listed above. Optionally, a primer layer can be applied to the substrate prior to the layer of functional copolymer.

[0065] In one embodiment, the substrate is porous, for example a porous membrane. EXAMPLES

[0066] 19 Comonomer incorporation measured by F-NMR

[0067] The degree of comonomer incorporation 19Measurements were performed by F-NMR. 19 F-NMR and 1 H-NMR spectra were acquired at 80 °C using a 5 mm TXO probe on a Bruker AV III 500 (11.7 T). For analysis, each sample was dissolved in DMSO-d6 at 80 °C for at least 24 h. The peak appearing at 93.5 ppm, corresponding to the -CF2- group alpha to the incorporated copolymer unit, was used as the basis for all the determinations for the material [-CH2-CF2-CH2-CH(R)-CH2-CF2- (where R represents a bond or a spacer group carrying a hydrophilic functional group)]. 19 The integrals were then integrated relative to the total integral of the F signal. The ratio of the values ​​determined from these integrals was taken as the comonomer incorporation. Using this method, the minimum detectable incorporation was determined to be 100 ppm. The ppm values ​​for monomer amount measurements are weight / weight.

[0068] Example 1: A solution of sodium undecylenate (NaUDA) was prepared by adding 2.0 g of undecylenic acid (UDA) to a solution of 192.0 g of deionized water and 6.0 g of 1 M sodium hydroxide (NaOH) with vigorous stirring.

[0069] To a 2 liter autoclave were added 1000 g deionized water, 1.6 g low molecular weight poly(acrylic acid) (BASF CP-10S) and 50 g of the NaUDA solution. The autoclave was deoxygenated by venting to 60 psi with nitrogen two more times. Agitation was started, the autoclave was heated to 83°C and pressurized to 650 psi with vinylidene fluoride. Feeds of 2.0 wt% potassium persulfate (KPS) and sodium acetate were started at 5.0 mL / min each. When the pressure began to drop, additional NaUDA feeds were started at 1.0 mL / min, the KPS feed was reduced to 1.0 mL / min, and the pressure was maintained by additional VDF feed. While continuing in this manner, the NaUDA feed rate was increased to relieve instantaneous VDF feed demand and maintained in the range of 500-1000 g / hr. The NaUDA feed was increased to 5.0 mL / min in this manner. All feeds were continued until a total of 700 g VDF had been fed to the reactor. The monomer feeds were stopped and the pressure was allowed to naturally drop for 10 minutes, at which point the reactor was vented to atmospheric pressure and cooled to room temperature. The latex was discharged from the reactor and dried overnight in a convection oven.

[0070] Example 2: The procedure outlined in Example 1 was followed except that the NaUDA solution concentration was increased to 3.0 wt % and the KPS solution concentration was increased to 4.0 wt % by using 6.0 g UDA, 18.0 g NaOH and 176.0 g deionized water.

[0071] Example 3: A solution of sodium vinylphosphonate (NaVPA) was prepared by adding 6.65 g of vinylphosphonic acid (VPA) to a solution of 123.1 g of 0.5N sodium hydroxide solution and 29.8 g of deionized water with vigorous stirring.

[0072] To a 2 liter autoclave were added 900 g deionized water, 2.3 g low molecular weight poly(acrylic acid) (BASF CP-10S), and 25 g of the NaVPA solution. The autoclave was deoxygenated by venting to 60 psi with nitrogen two more times. Agitation was started, the autoclave was heated to 83° C., and pressurized to 650 psi with vinylidene fluoride. Feeds of potassium persulfate (KPS), each 4.0 wt.%, were started at 5.0 mL / min. When the pressure began to drop, additional NaVPA feeds were started at 1.0 mL / min, the KPS feed was reduced to 1.0 mL / min, and pressure was maintained by additional VDF feed. While continuing in this manner, the NaVPA feed rate was increased to relieve momentary VDF feed demands and maintained in the range of 500-1000 g / hr. The NaVPA feed was increased to 5.0 mL / min in this manner. All feeds were continued until a total of 700 g VDF had been fed to the reactor. The monomer feeds were stopped and the pressure was allowed to naturally drop for 10 minutes, at which point the reactor was vented to atmospheric pressure and cooled to room temperature. The latex was discharged from the reactor and dried overnight in a convection oven.

[0073] Example 4: The procedure outlined in Example 3 was followed, except the KPS solution concentration was reduced to 2.5 wt%. The melting point (DSC 2nd heat) was measured to be 161.8° C. The crystallization enthalpy was 48.0 J / g.

[0074] Example 5: Example (Acrylamide): To a 2 liter autoclave is added 900 g deionized water, 2.3 g low molecular weight poly(acrylic acid) (BASF CP-10S) and 25 g of a 1.0 wt% acrylamide solution in water. The autoclave is deoxygenated by pressing to 60 psi with nitrogen and then venting two more times. Agitation is started, the autoclave is heated to 83°C, and pressurized to 650 psi with vinylidene fluoride. Feeds of potassium persulfate (KPS), each 4.0 wt%, are started at 5.0 mL / min. When the pressure begins to drop, an additional acrylamide feed is started at 1.0 mL / min, the KPS feed is reduced to 1.0 mL / min, and the additional VDF feed is added to keep the pressure at 1.0%. Maintain pressure. Continue feeds in this manner while increasing the acrylamide feed rate to relieve momentary VDF feed demands, maintaining the range of 500-1000 g / hr. Increase acrylamide feed in this manner to 5.0 mL / min. Continue all feeds until a total of 700 g VDF has been delivered to the reactor. Stop monomer feeds and allow pressure to naturally drop for 10 minutes, at which point vent the reactor to atmospheric pressure and cool to room temperature. Drain the latex from the reactor and dry overnight in a convection oven.

[0075] Example 6: Example (vinylene carbonate): To a 2 liter autoclave, add 900 g deionized water, 2.3 g low molecular weight poly(acrylic acid) (BASF CP-10S) and 25 g of a 1.0 wt% vinylene carbonate solution in water. The autoclave is deoxygenated by pressing to 60 psi with nitrogen and then venting two more times. Agitation is started, the autoclave is heated to 83°C, and pressurized to 650 psi with vinylidene fluoride. Feeds of 4.0 wt% potassium persulfate (KPS) are started at 5.0 mL / min each. When the pressure begins to drop, additional feeds of vinylene carbonate are started at 1.0 mL / min, the KPS feed is reduced to 1.0 mL / min, and pressure is maintained with additional VDF feed. Continue feeding in this manner while increasing the vinylene carbonate feed rate to relieve momentary VDF feed demands and maintain it in the range of 500-1000 g / hr. Increase the vinylene carbonate feed in this manner to 5.0 mL / min. Continue all feeds until a total of 700 g VDF has been fed to the reactor. Stop the monomer feeds and allow the pressure to naturally drop for 10 minutes, at which point vent the reactor to atmospheric pressure and cool to room temperature. Drain the latex from the reactor and dry overnight in a convection oven.

[0076] Example 7: Example (vinylene carbonate): To a 2 liter autoclave, add 900 g deionized water, 2.3 g low molecular weight poly(acrylic acid) (BASF CP-10S) and 25 g 1.0 wt% carboxyethyl vinyl ether in water. The autoclave is deoxygenated by pressing to 60 psi with nitrogen and then venting two more times. Agitation is started, the autoclave is heated to 83°C, and pressurized to 650 psi with vinylidene fluoride. Feeds of potassium persulfate (KPS), each 4.0 wt%, are started at 5.0 mL / min. When the pressure begins to drop, an additional feed of carboxyethyl vinyl ether is started at 1.0 mL / min, the KPS feed is reduced to 1.0 mL / min, and pressure is maintained by additional VDF feed. Feeds are continued in this manner while the carboxyethyl vinyl ether feed rate is increased to relieve momentary VDF feed demands, maintaining the range of 500-1000 g / hr. Increase the carboxyethyl vinyl ether feed in this manner to 5.0 mL / min. Continue all feeds until a total of 700 g VDF has been fed to the reactor. Stop the monomer feeds and allow the pressure to naturally drop for 10 minutes, at which point vent the reactor to atmospheric pressure and cool to room temperature. Drain the latex from the reactor and dry overnight in a convection oven.

[0077] Example 8: A solution of allyloxyethanol (AOE) was prepared by adding 6.0 g of AOE to 294.0 g of deionized water with vigorous stirring.

[0078] To a 2 liter autoclave were added 900 g deionized water, 2.3 g low molecular weight poly(acrylic acid) (BASF CP-10S), and 10 g of the AOE solution. The autoclave was deoxygenated by venting to 60 psi with nitrogen two more times. Agitation was started, the autoclave was heated to 83°C, and pressurized to 650 psi with vinylidene fluoride. Feeds of 4.0 wt% potassium persulfate (KPS) were started at 5.0 mL / min each. When the pressure began to drop, additional AOE feeds were started at 1.0 mL / min, the KPS feed was reduced to 1.0 mL / min, and pressure was maintained by additional VDF feed. While continuing in this manner, the AOE feed rate was increased to relieve instantaneous VDF feed demand and maintained in the range of 500-1000 g / hr. The AOE feed was increased to 5.0 mL / min in this manner. All feeds were continued until a total of 700 g VDF had been fed to the reactor. The monomer feeds were stopped and the pressure was allowed to naturally drop for 10 minutes, at which point the reactor was vented to atmospheric pressure and cooled to room temperature. The latex was discharged from the reactor and dried overnight in a convection oven.

[0079] Example 9: The procedure outlined in Example 3 was followed, except the AOE solution concentration was increased to 4.0 wt % (12.0 g AOE + 288.0 g deionized water).

[0080] Example 10: A solution of allyloxypropanediol (AOPD) was prepared by adding 12.0 g of AOPD to 288.0 g of deionized water with vigorous stirring.

[0081] To a 2 liter autoclave were added 900 g deionized water, 2.3 g low molecular weight poly(acrylic acid) (BASF CP-10S) and 10 g of the AOPD solution. The autoclave was deoxygenated by venting to 60 psi with nitrogen two more times. Agitation was started, the autoclave was heated to 83°C and pressurized to 650 psi with vinylidene fluoride. Feeds of potassium persulfate (KPS), each 4.0 wt%, were started at 5.0 mL / min. When the pressure began to drop, additional AOPD feeds were started at 1.0 mL / min, the KPS feed was reduced to 1.0 mL / min, and the pressure was maintained by additional VDF feed. While continuing in this manner, the AOPD feed rate was increased to relieve instantaneous VDF feed demand and maintained in the range of 500-1000 g / hr. The AOPD feed was increased to 5.0 mL / min in this manner. All feeds were continued until a total of 700 g VDF had been fed to the reactor. The monomer feeds were stopped and the pressure was allowed to naturally drop for 10 minutes, at which point the reactor was vented to atmospheric pressure and cooled to room temperature. The latex was discharged from the reactor and dried overnight in a convection oven.

[0082] Example 11: The procedure outlined in Example 10 was followed, except the concentration of the KPS solution was reduced to 2.5% by weight.

[0083] Example 12: A solution of acrylic acid (AA) and AOE (AA / AOE) was prepared by adding 6.0 g of AA and 6.0 g of AOE to 288.0 g of deionized water with vigorous stirring.

[0084] To a 2 liter autoclave were added 900 g deionized water, 2.3 g low molecular weight poly(acrylic acid) (BASF CP-10S), and 10 g of the AOPD solution. The autoclave was deoxygenated by venting to 60 psi with nitrogen two more times. Agitation was started, the autoclave was heated to 83°C, and pressurized to 650 psi with vinylidene fluoride. Feeds of potassium persulfate (KPS), each 4.0 wt%, were started at 5.0 mL / min. When the pressure began to drop, additional AA / AOE feeds were started at 1.0 mL / min, the KPS feed was reduced to 1.0 mL / min, and pressure was maintained by additional VDF feed. While continuing in this manner, the AA / AOE feed rate was increased to relieve instantaneous VDF feed demand and maintained in the range of 500-1000 g / hr. The AA / AOE feed was increased to 5.0 mL / min in this manner. All feeds were continued until a total of 700 g VDF had been fed to the reactor. The monomer feeds were stopped and the pressure was allowed to naturally drop for 10 minutes, at which point the reactor was vented to atmospheric pressure and cooled to room temperature. The latex was discharged from the reactor and dried overnight in a convection oven.

[0085] Cathode Formulation and Fabrication: The procedure for preparing the cathode slurry for laboratory scale is described here. First, the PVDF copolymer of the present invention is dissolved in N-methylpyrrolidone (NMP) solvent, typically at a concentration of 5-10% by weight. To this binder solution, a conductive carbon additive, e.g. SuperP-Li from Timcal, is added and mixed for 120 seconds at 2000 rpm using a centrifugal planetary mixer Thinky AR-310. This mixing is repeated three times with 1 minute of air cooling in between. Once the conductive carbon is dispersed in the binder solution, an active material such as Celcore® NMC622 (Umicore) and a small amount of NMP are added to the mixture, typically mixed for 60 seconds at 2000 rpm to form a thick homogenous paste. Then, a small amount of NMP is added to the paste and mixed for 60 seconds / 2000 rpm to gradually reduce the solids content of the slurry (about 1.5% for each addition of NMP solution) and reduce the viscosity. This dilution process is repeated multiple times until the viscosity of the slurry reaches a suitable level for coating (typically 3000-15000 cP@1 / sec shear rate).The typical formulation for our laboratory cathodes is active / carbon / PVDF=97 / 1.5 / 1.5 (wt / wt / wt) on a dry basis.

[0086] The cathode slurry is then cast (15mm thick) onto aluminium foil using an adjustable doctor blade on an automatic film coater (Elcometer 4340). The wet casting is then transferred to a convection oven and dried at 120°C for 30 minutes. After drying, the electrode is calendered using a roll mill (IRM, International Rolling Mills) to a thickness of 3.2-3.6 g / cm. 3 Final density, typical value 3.4g / cm 3 The typical surface mass loading of a dry cathode is 180-220g / m 2 It is.

[0087] Peel strength was obtained for the cathodes by 180° peel testing using ASTM method D903 with three modifications. The first modification was that the pull rate used was 50 mm / min (25 mm / min peel rate). The second modification was that the 2 week conditioning period at controlled humidity and temperature was not performed. The cathodes were tested one day after fabrication. The third modification was that the cathodes were attached to the alignment plate using 3M 401M double-sided paper tape, and the flexible aluminum foil current collector was peeled off by the grips of the testing machine.

[0088] [Table 1] *Rounded to the nearest 100 ppm based on NMR analytical sensitivity. ppm is measured weight / weight.

Claims

1. 1. A fluorinated copolymer comprising a fluorinated vinyl monomer and one or more hydrophilic monomers, wherein the hydrophilic monomers are selected from the group consisting of vinyl alkyl acids, vinyl phosphonates, functional acrylamides, carbonates, vinyl ethers, alkoxy compounds and dual hydrophilic group monomers.

2. 10. The copolymer of claim 1 comprising up to 10.0% by weight of said hydrophilic monomer.

3. The copolymer of claim 1 , wherein the fluorinated vinyl monomer comprises vinylidene fluoride.

4. 2. The copolymer of claim 1, wherein at least one of said hydrophilic monomers contains at least one halogen on a vinyl carbon.

5. The copolymer of claim 4 , wherein the at least one halogen comprises fluorine.

6. 2. The copolymer of claim 1 , wherein the vinyl alkyl acid comonomer has the formula (M1): 【Chemistry 1】 (where: R 1 , R 2 and R 3 is hydrogen or a halogen (F, Cl, Br, I); R 4 is C 1 ~C 16 Linear, branched, aryl or cyclic alkyl groups, C 1 ~C 16 fluorinated linear, branched, aryl or cyclic alkyl groups, oligomers of hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide; R 5 represents carboxylic acid (C(O)OH), alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - N.H. 4 + ), alkyl ammonium carboxylate (COO - N(Alk) 4 + ), alcohols (OH), amides (C(O)NH 2 ), dialkylamide (C(O)NAlk 2 ), sulfonic acid (S(O)(O)OH), alkali metal sulfonate (S(O)(O)O - M + ), ammonium sulfonate (S(O)(O)O - N.H. 4 + ), sulfonic acid alkyl ammonium salt (S(O)(O)O - N(Alk) 4 + )

7. 2. The copolymer of claim 1 , wherein the vinyl phosphonate comonomer has the formula (M2): 【Chemistry 2】 (where: R 1 , R 2 and R 3 is hydrogen or a halogen (F, Cl, Br, I); R 4 and R 5 are hydrogen, C 1 ~C 16 Linear alkyl, branched alkyl, aryl or cyclic alkyl group, C 1 ~C 16 Fluorinated linear alkyl, branched alkyl, aryl or cyclic alkyl groups, oligomers of hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide, alkali metal ions (Li + , Na + , K + , Rb + , Cs + ), ammonium ion (NH 4 + ) or alkyl ammonium (NAlk 4 + )

8. 2. The copolymer of claim 1, wherein the functional acrylamide comonomer has the formula (M3): 【Chemistry 3】 (Here, R 1 , R 2 and R 3 is hydrogen or a halogen (F, Cl, Br, I); R 4 and R 6 are hydrogen, C 1 ~C 16 Linear, branched, aryl or cyclic alkyl groups, C 1 ~C 16 fluorinated linear, branched, aryl or cyclic alkyl groups, oligomers of hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide; R 5 and R 7 are respectively carboxylic acid (C(O)OH), carboxylic acid alkali metal salt (COO - M + ), ammonium carboxylate (COO - N.H. 4 + ), alkyl ammonium carboxylate (COO - N(Alk) 4 + ), alcohols (OH), amides (C(O)NH 2 ), dialkylamide (C(O)NAlk 2 ), sulfonic acid (S(O)(O)OH), alkali metal sulfonate (S(O)(O)O - M + ), ammonium sulfonate (S(O)(O)O - N.H. 4 + ), sulfonic acid alkyl ammonium salt (S(O)(O)O - N(Alk) 4 + ), ketone (C(O)) or acetylacetonate (C(O)-CH 2 -C(O)), or phosphonate (P(O)(OH) 2 ), alkali metal or ammonium phosphonates.

9. 2. The copolymer of claim 1, wherein the carbonate comonomer has the formula (M4): 【Chemistry 4】 (Here, R 1 , R 2 and R 3 is hydrogen or a halogen (F, Cl, Br, I); R 4 is a bond, C 1 ~C 16 Linear alkyl, branched alkyl, aryl or cyclic alkyl group, C 1 ~C 16 a fluorinated linear alkyl, branched alkyl, aryl or cyclic alkyl group; R 5 C contains a carbonate group as part of the cyclic structure 1 ~C 16 Cyclic alkyl group or C 1 ~C 16 It is a fluorinated cyclic alkyl group.

10. 2. The copolymer of claim 1 , wherein the vinyl ether comonomer has the formula (M5): 【Chemistry 5】 (where: R 1 , R 2 and R 3 is hydrogen or a halogen (F, Cl, Br, I); R 4 is C 1 ~C 16 Linear, branched, aryl or cyclic alkyl groups, C 1 ~C 16 fluorinated linear, branched, aryl or cyclic alkyl groups, oligomers of hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide; R 5 represents carboxylic acid (C(O)OH), alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - N.H. 4 + ), alkyl ammonium carboxylate (COO - N(Alk) 4 + ), alcohols (OH), amides (C(O)NH 2 ), dialkylamide (C(O)NAlk 2 ), sulfonic acid (S(O)(O)OH), alkali metal sulfonate (S(O)(O)O - M + ), ammonium sulfonate (S(O)(O)O - N.H. 4 + ), sulfonic acid alkyl ammonium salt (S(O)(O)O - N(Alk) 4 + ), ketone (C(O)) or acetylacetonate (C(O)-CH 2 -C(O)).

11. 2. The copolymer of claim 1, wherein the allyloxy comonomer has the formula (M6): 【Chemistry 6】 (where: R 1 , R 2 and R 3 is hydrogen or a halogen (F, Cl, Br, I); R 4 is CH 2 Or CF 2 and R 5 is C 1 ~C 16 Linear, branched, aryl or cyclic alkyl groups, C 1 ~C 16 fluorinated linear, branched, aryl or cyclic alkyl groups, oligomers of hexafluoropropylene oxide or oligomers of tetrafluoroethylene oxide; R 6 represents carboxylic acid (C(O)OH), alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - N.H. 4 + ), alkyl ammonium carboxylate (COO - N(Alk) 4 + ), alcohols (OH), amides (C(O)NH 2 ), dialkylamide (C(O)NAlk 2 ), sulfonic acid (S(O)(O)OH), alkali metal sulfonate (S(O)(O)O - M + ), ammonium sulfonate (S(O)(O)O - N.H. 4 + ), sulfonic acid alkyl ammonium salt (S(O)(O)O - N(Alk) 4 + ), ketone (C(O)) or acetylacetonate (C(O)-CH 2 -C(O)), or phosphonate (P(O)(OH) 2 ), alkali metal or ammonium phosphonates.

12. 2. The copolymer of claim 1, wherein said multi-hydrophilic functional comonomer is selected from the group consisting of itaconic acid, maleic acid, glutaconic acid, and fumaric acid and their anhydrides, alkali metal salts, ammonium salts, and mono-, di-, tri-, and tetraalkylammonium salts.

13. A formulation comprising a fluorinated copolymer according to any one of claims 1 to 12 in a solvent.

14. 14. The formulation of claim 13, wherein the solvent is selected from the group consisting of N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF), triethylphosphite (TEP), acetone, tetrahydrofuran, methyl ethyl ketone (MEK), methyl isobutyl ketone (MiBK), ethyl acetate (EA), butyl acetate (BA), dimethyl carbonate (DMC), diethyl carbonate (DEC), and methyl ethyl carbonate (MEC).

15. 14. The formulation of claim 13, further comprising activated carbon and metal particles suspended in said solvent, said metal particles being selected from the group consisting of lithium iron phosphate (LFP), lithium nickel manganese cobalt oxide (NMC), lithium manganese cobalt oxide, lithium nickel cobalt aluminum oxide, lithium manganese oxide and lithium nickel manganese (LMNO).

16. 13. A process for producing the fluorinated copolymer of claim 1 in an aqueous reaction medium, comprising: a) forming an aqueous emulsion comprising at least one initiator, a stabilizer, at least one fluorinated vinyl monomer, and at least one hydrophilic monomer selected from the group consisting of vinyl alkyl acids, vinyl phosphonates, functional acrylamides, carbonates, vinyl ethers, alkoxy compounds, and dual hydrophilic group monomers; b) initiating copolymerization of said at least one fluorinated vinyl monomer with said hydrophilic monomer under heat and superatmospheric pressure with stirring; The method comprising:

17. 17. The method of claim 16, wherein the aqueous medium additionally comprises at least one buffering agent.

18. The process of claim 16 or 17, wherein the polymerization is carried out at a temperature of from about 70 to about 125°C.

19. The process of any of claims 16 to 18, wherein the polymerization is carried out at a polymerization pressure of from about 2750 to about 6900 kPa.

20. The method of any one of claims 16 to 19, wherein the initiator is a persulfate or an organic peroxide.

21. An article comprising the formulation according to any one of claims 11 to 13, said article being a battery electrode film, in particular a positive electrode for a lithium-ion battery.

22. A battery comprising the fluorinated copolymer of any one of claims 1 to 12.

23. A coated substrate to which the copolymer of any one of claims 1 to 12 has been applied as a latex in water or as a solvent solution.

24. A porous membrane comprising a copolymer according to any one of claims 1 to 12 applied as a latex in water or as a solvent solution.

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