Functional fluoropolymer

Abstract

The present invention relates to a novel linear semicrystalline functional fluoropolymer obtained by copolymerizing a fluorinated vinyl monomer with a hydrophilic monomer selected from vinyl alkyl acids, vinyl phosphonates, functional acrylamides, carbonates, vinyl ethers, alkoxy compounds, and bihydrophilic group monomers.

Description

Technical Field

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

Background Art

[0002] Fluoropolymers have conventionally been used in applications that require special properties such as low surface energy, high resistance to chemical attack, aging resistance, and electrochemical stability. However, these advantageous properties also make the handling of fluoropolymers difficult and limit their use. For example, since there are no functional groups on the fluoropolymer, it is difficult to adhere to a substrate, promote cross-linking, provide a site for later chemical modification, be wetted by water, or add hydrophilic characteristics. There is a need for fluorinated polymers having modified properties (such as functional groups) that can enhance these properties.

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

[0004] U.S. Patent No. 5,415,958 describes the copolymerization of vinylidene fluoride and an unsaturated dibasic acid monoester polar monomer to introduce a carbonyl group into the main chain of PVDF to improve its adhesion to various substrates.

[0005] U.S. Patent No. 8,337,725 discloses the copolymerization of vinylidene fluoride with at least one hydrophilic (meth)acrylic monomer of the following formula.

Chemical formula

Prior art documents

Patent documents

[0006]

Patent document 1

Patent document 2

Patent document 3

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

[0008] There was no knowledge in this technical field that a functional fluoropolymer capable of improving the adhesion to a substrate compared to a non-functional fluoropolymer while maintaining good mechanical and thermal properties could be obtained by copolymerizing a fluorinated vinyl monomer and a hydrophilic comonomer which may optionally have a halogen functional group. [Means for Solving the Problems]

[0009] The present invention relates to a fluorinated copolymer containing a vinyl monomer and a hydrophilic monomer.

[0010] The present invention further relates to a formulation containing a fluorinated copolymer in a solvent, which may further contain 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 relates to a method for producing a fluorinated copolymer in an aqueous reaction medium, a) forming an aqueous emulsion containing at least one initiator, a stabilizer, at least one fluoromonomer, and a hydrophilic monomer; b) Initiating the copolymerization of the at least one fluoromonomer and the hydrophilic monomer under heat and pressure while stirring: The method including this is also contemplated.

[0012] The present invention further relates to an article formed from the fluorinated copolymer, which benefits from the special properties of the functionalized copolymer. These articles include electrodes or separators for batteries or capacitors; hydrophilic porous membranes or hollow fiber membranes; articles having at least one surface coated with the functional fluoropolymer, impregnation of woven and non-woven fibers, and multi-layer structures in which the functional fluoropolymer forms a tie layer between a fluoropolymer layer and a polymer layer incompatible with the fluoropolymer layer, etc., and are useful for such applications.

Embodiments for Carrying Out the Invention

[0013] Fluoropolymers, particularly poly(vinylidene fluoride) (PVDF) and its copolymers, find use as binders in electrode articles used in lithium-ion batteries. As the demand for higher battery performance increases, the need to reduce the binder content in the electrodes has been increasing. To reduce the binder content, it is most important to improve the performance of the binder material. The initial performance is determined by an adhesion test. According to this test, the formulated electrode is subjected to a peel test. Improvement in this test leads to the possibility of improving the binding performance, reducing the overall binder loading, increasing the loading of the active material, and improving the battery capacity. Copolymers of fluorinated vinyl monomers and acid-functional comonomers have been shown to provide an improvement in this type of adhesion performance. These approaches also have the problem that the reaction productivity is low and it is difficult to supply a sufficient amount of material to a rapidly growing market. Here, the present inventors present a novel copolymer and method with greatly improved productivity (i.e., shortened polymerization time).

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

[0015] The fluorinated vinyl monomer is selected from the group consisting of: 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 vinyl 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 comonomer is selected from vinyl alkyl acids, vinyl phosphonates, functional acrylamides, carbonates, vinyl ethers, allyloxy compounds, and vinyl or allyl double hydrophilic group monomers and combinations thereof.

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

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

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

[0022] The present invention further relates to a formulation comprising a fluorinated copolymer in a solvent. The solvent is preferably selected from the following: N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), triethyl phosphite (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 contains activated carbon and lithium salt particles in suspension in the solvent. The lithium salt particles are selected from the group consisting 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 a formulation is particularly suitable for forming a battery electrode film, especially a positive electrode for a lithium-ion battery. The present invention encompasses a battery comprising the fluorinated copolymer described herein.

[0024] The present invention further contemplates a method for preparing a fluorinated copolymer in an aqueous reaction medium, the method comprising a) forming an aqueous emulsion comprising at least one initiator, a stabilizer, at least one fluorinated vinyl monomer and the hydrophilic monomer described above, b) starting the copolymerization of the at least one fluorinated vinyl monomer and the hydrophilic monomer under heat and pressure while stirring including this.

[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 the hydrophilic monomers, and optionally one or more surfactants, chain transfer agents, and / or antifouling agents. The air may be purged from the reactor before introducing the monomers. Water is added before bringing the reactor to the desired starting temperature, but the other substances may be added before or after bringing the reactor to that temperature. To initiate and maintain the polymerization reaction, at least one radical initiator is added. Additional monomers may be optionally added to replenish the consumed monomers, and other substances may be optionally added during the progress of the polymerization to maintain 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 polymer can be linear, branched, star-shaped, comb-shaped, block, or any other arbitrary structure. The copolymer units of the polymer may be homogeneously, heterogeneously, or gradient-distributed. All documents cited are incorporated herein by reference. As used herein, unless otherwise specified, percentages mean weight %. Unless otherwise specified, the molecular weight is the weight average molecular weight measured by GPC using polymethyl methacrylate as the standard substance. When the polymer contains some crosslinking and GPC cannot be applied due to the insoluble polymer fraction, the molecular weight of the soluble fraction / gel fraction or the soluble fraction after extraction from the gel is used. The crystallinity and melting temperature are measured by DSC described in ASTM method D3418 at a heating rate of 10 °C / min. The melt viscosity is measured at 230 °C according to ASTM method D3835 and is represented by kilopascals @ 100 seconds -1 represented by.

[0027] Hydrophilic monomer The hydrophilic comonomer used in combination with one or more fluoromonomers includes, but is not limited to, one or more of the following, mixtures of more than one monomer in a particular class, and mixtures of two or more monomers from the various classes below that are blended together to form a terpolymer:

[0028] A) Vinyl alkyl acid having the following formula as comonomer (M1)

Chemical formula

[0029] B) Vinyl alkyl acid having the following formula M2: [Chemical formula] Here, R1, R2, and R3 are hydrogen or halogen (F, Cl, Br, I), R4 and R5 are each 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 group, oligomer of hexafluoropropylene oxide or oligomer of tetrafluoroethylene oxide, alkali metal ion (Li + , Na + , K + , Rb + , Cs + ), ammonium ion (NH4 + ), or alkylammonium (NAlk4 + ).

[0030] C) As comonomer (M3), a functionalized acrylamide having the following formula [Chemical formula] Here, R1, R2, and R3 are hydrogen or halogen (F, Cl, Br, I), R4 and R6 are each independently hydrogen, C1-C 16 linear, branched, aryl or cyclic alkyl group, C1-C 16 fluorinated linear, branched, aryl or cyclic alkyl group, oligomer of hexafluoropropylene oxide or oligomer of tetrafluoroethylene oxide, R5 and R7 are each independently carboxylic acid (C(O)OH), alkali metal salt of carboxylic acid (COO - M + ), ammonium salt of carboxylic acid (COO - NH4 + ), alkylammonium salt of carboxylic acid (COO - N(Alk)4 +) Alcohol (OH), amide (C(O)NH2), dialkylamide (C(O)NAlk2), sulfonic acid (S(O)(O)OH), alkali metal sulfonate (S(O)(O)O - M + ) Ammonium sulfonate (S(O)(O)O - NH4 + ) Alkylammonium sulfonate (S(O)(O)O - N(Alk)4 + ) Ketone (C(O)) or acetylacetonate (C(O)-CH2-C(O)), or phosphonate (P(O)(OH)2), alkali metal or ammonium phosphonate.

[0031] D) Carbonate containing comonomer M4

Chemical formula

[0032] E) Vinyl ether having the following formula as comonomer (M5)

Chemical formula

[0033] F) An allyloxy compound having the following formula as a comonomer (M6)

Chemical formula

[0034] G) Multiple hydrophilic group comonomers

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

[0036] The hydrophilic comonomer can be used in the reactor, for example, in an amount of about 0.01 to about 15% by weight, based on all monomers, preferably in an amount of about 0.01 to about 5% by weight, based on all monomers. In various embodiments, the total amount of the 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 all monomers. In another embodiment, the total amount of the 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, 5.0% by weight or less, based on all monomers. The hydrophilic comonomer can be used in solution form, such as an aqueous solution, for convenience of handling.

[0037] The polymer can 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] Surfactant The surfactant used for polymerization can be any surfactant well-known in the art to be useful in the emulsion polymerization of PVDF, and includes perfluorinated surfactants, partially fluorinated surfactants, and non-fluorinated surfactants. In a preferred embodiment, the PVDF emulsion of the present disclosure can be free of fluorosurfactants, and fluorosurfactants are not used at any stage 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, alkyl phosphonates, and siloxane-based surfactants.

[0039] The surfactant can also be used in combination with the hydrophilic comonomer to provide further stability to the polymer emulsion. Preferred surfactants are non-fluorinated hydrocarbon surfactants, siloxane-based surfactants, or combinations thereof. For example, a hydrophilic (meth)acrylic comonomer can be used in combination with sodium dodecylbenzenesulfonate (SDDBS), sodium octylsulfonate, sodium lauryl sulfate, ammonium lauryl sulfate, sodium laureth sulfate, and others. In certain embodiments of the present invention, no fluorosurfactant is present in the aqueous emulsion and / or no fluorosurfactant is introduced during the 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 functionalized cellulose.

[0040] Initiator The terms "initiator", as well as the expressions "radical initiator" and "free radical initiator", refer to chemical substances 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. "Initiator" also includes redox systems useful for providing a source of free radicals. The expressions "radical" and "free radical" refer to chemical species containing at least one unpaired electron.

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

[0042] The radical initiator can include persulfates, 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 wt% (based on the total amount of monomers added to the reaction mixture).

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

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

[0045] The radical initiator can include a redox system. The "redox system" means a system containing an oxidizing agent, a reducing agent, and optionally an accelerator as an electron transfer medium. Examples of the oxidizing agent include persulfates; peroxides such as hydrogen peroxide; hydroperoxides such as t-butyl hydroperoxide and cumene hydroperoxide; and oxidizing metal salts such as ferric sulfate. Examples of the reducing agent include sodium formaldehyde sulfoxylate, sodium sulfite, potassium sulfite, ascorbic acid, bisulfites, metabisulfites, and reduced metal salts. The accelerator is a component of the redox system and can promote the overall reaction by reacting with both the oxidizing agent and the reducing agent in various oxidation states. Examples of the accelerator include 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 monomers. The optional accelerator can be used in an amount of about 0.005 to about 0.025% by weight based on the total monomers. The redox system is described in G.S. Misra and U.D.N. Bajpai, Prog. Polym. Sci., 1982, 8(1-2), pp. 61-131.

[0046] Chain transfer agent The chain transfer agent is added to the polymerization to control the molecular weight of the product. These can be added to the polymerization at a single location at the beginning of the reaction, or can be added to the polymerization gradually or continuously throughout the reaction. The amount and method of adding the chain transfer agent depend on the activity of the chain transfer agent used and the molecular weight desired for the polymer product. The amount of the chain transfer agent added to the polymerization reaction is preferably about 0.05 to about 5% by weight, more preferably about 0.1 to about 2% by weight, based on the total weight of the monomers added to the reaction mixture.

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

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

[0049] The buffer is an organic acid or inorganic acid or their alkali metal salts, or a base or a salt of such an organic acid or inorganic acid, having 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 value and can include those having such values. 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. The preferred amount of the sodium acetate buffer is about 50 wt% to about 150 wt% based on the weight of the persulfate initiator added to the reaction. In one preferred embodiment, the initiator feed contains potassium persulfate and sodium acetate in approximately equal weights in an aqueous solution.

[0051] Antifouling agent Paraffin wax or hydrocarbon oil, when added to the reaction, acts as an anti-fouling agent to minimize or prevent the adhesion of polymers to the parts of the reactor. Any long-chain saturated hydrocarbon wax or oil can perform this function. The amount of oil or wax added to the reactor is an amount that functions to minimize the formation of polymer deposits on the parts of the reactor. This amount generally varies in proportion to the internal surface area of the reactor, and can be changed from about 1 to about 40 mg per 1 cm of the internal surface area of the reactor. 2 It can be changed. The amount of paraffin wax or hydrocarbon oil is preferably about 5 mg per 1 cm of the reactor surface area. 2

[0052] Copolymerization conditions The temperature employed for the polymerization can be changed, for example, from 20 to 130 °C, depending on the selected initiator system. 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 be changed from 280 to 20000 kPa, depending on the capacity of the reactor, the selected initiator system and the selection of the monomers. This polymerization pressure is preferably from 2000 to 11000 kPa, particularly preferably from 2750 to 6900 kPa.

[0054] The polymerization is carried out under stirring or other agitation. The stirring / agitation can be constant or can be changed to optimize the process conditions during the progress of the polymerization. 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 method of the present invention, a pressurized polymerization reactor equipped with a stirrer and heat control means is charged with water, preferably deionized water, one or more halogenated monomers (1) and at least one fluorinated vinyl monomer. This mixture may optionally contain one or more surfactants, buffers, anti-fouling agents or chain transfer agents for adjusting the molecular weight of the polymer product.

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

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

[0058] In one embodiment, water, initiator, hydrophilic monomer and optionally surfactant, antifouling agent, chain transfer agent and / or buffer are charged to the reactor and the reactor is heated to the desired reaction temperature. Then the fluorinated vinyl monomer is fed to the reactor, preferably at a rate that provides a substantially constant pressure.

[0059] Alternatively, the fluorinated vinyl monomer, hydrophilic monomer and initiator can be fed to the reactor together with one or more optional components. Other variations of 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 left for an appropriate 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 monomer is vented to atmospheric pressure. Then the aqueous reaction medium containing the copolymer is recovered from the reactor as a latex. This latex consists of a stable mixture of the reaction components, namely water, hydrophilic monomer, initiator (and / or decomposition products of the initiator) and copolymer solids.

[0062] Generally, the latex contains about 10 to about 50% by weight of copolymer solids. The polymers in the latex can be in the form of small particles having a size in the range of about 30 nm to about 800 nm.

[0063] Handling of the product The product of the copolymerization is a latex, which can usually be used in that form after filtering out solid by-products from the polymerization process, or it 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 may be the same as or different from the surfactant present during polymerization (if used). The surfactant added later can be, for example, an ionic or non-ionic surfactant. In one embodiment of the present invention, no fluorosurfactant is added to the latex. For the solid product, the latex can be coagulated mechanically or by adding a salt or an 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 present invention is applied to a substrate as a latex in water or as a solvent solution, and the solvent is selected from those listed above. Optionally, a primer layer can also be applied to the substrate before the layer of the functional copolymer.

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

Examples

[0066] 19 Measurement of comonomer incorporation by F-NMR

[0067] Degree of comonomer incorporation 19Measured by F-NMR. 19 F-NMR and 1 H-NMR spectra were acquired at 80 °C using a 5 mm TXO probe for 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 α-position -CF2- group for the incorporated copolymer units was integrated in relation to the total integration of all 19 F signals. The ratio of the values determined from these integrations was adopted as the incorporation amount of the comonomer. Using this method, it was determined that the minimum detectable incorporation amount was 100 ppm. The ppm of the monomer amount measurement is 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] Into a 2-liter autoclave, 1000 g of deionized water, 1.6 g of low molecular weight poly(acrylic acid) (BASF CP-10S), and 50 g of the NaUDA solution were added. The autoclave was deoxygenated by repeating the operation of pressurizing to 60 psi with nitrogen and then venting two or more times. Stirring was started, the autoclave was heated to 83 °C, and pressurized to 650 psi with vinylidene fluoride. The supply of 2.0 wt% potassium persulfate (KPS) and sodium acetate was started at 5.0 mL / min each. When the pressure began to drop, an additional supply of NaUDA was started at 1.0 mL / min, the KPS supply was reduced to 1.0 mL / min, and the pressure was maintained by an additional supply of VDF. While continuing the supply in this manner, the supply rate of NaUDA was increased to relieve the instantaneous VDF supply demand and maintained in the range of 500 - 1000 g / hour. The NaUDA supply was increased to 5.0 mL / min in this manner. All supplies were continued until a total of 700 g of VDF was supplied to the reactor. The monomer supply was stopped, left for 10 minutes to allow the pressure to drop naturally, 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 of UDA, 18.0 g of NaOH, and 176.0 g of 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 0.5 N sodium hydroxide solution and 29.8 g of deionized water with vigorous stirring.

[0072] Into a 2-liter autoclave, 900 g of deionized water, 2.3 g of low molecular weight poly(acrylic acid) (BASF CP-10S), and 25 g of the NaVPA solution were added. The autoclave was deoxygenated by repeating the operation of pressurizing to 60 psi with nitrogen and then venting two or more times. Stirring was started, the autoclave was heated to 83 °C, and pressurized to 650 psi with vinylidene fluoride. The supply of 4.0 wt% potassium persulfate (KPS) was started at 5.0 mL / min each. When the pressure began to drop, the additional supply of NaVPA was started at 1.0 mL / min, the KPS supply was reduced to 1.0 mL / min, and the pressure was maintained by additional VDF supply. While continuing the supply in this manner, the NaVPA supply rate was increased to relieve the instantaneous VDF supply demand and maintained in the range of 500 - 1000 g / hour. The NaVPA supply was increased to 5.0 mL / min in this manner. All supplies were continued until a total of 700 g of VDF was supplied to the reactor. The monomer supply was stopped, left for 10 minutes to allow the pressure to drop naturally, 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 that the KPS solution concentration was lowered to 2.5 wt%. The melting point (second heating by DSC) was measured to be 161.8 °C. The crystallization enthalpy was 48.0 J / g.

[0074] Example 5: Example (Acrylamide): Add 900 g of deionized water, 2.3 g of low molecular weight poly(acrylic acid) (BASF CP-10S), and 25 g of a 1.0 wt% acrylamide aqueous solution to a 2-liter autoclave. Deoxygenate the autoclave by repeating the operation of pressurizing to 60 psi with nitrogen and then venting two or more times. Start stirring, heat the autoclave to 83 °C, and pressurize to 650 psi with vinylidene fluoride. Start the supply of 4.0 wt% potassium persulfate (KPS) at 5.0 mL / min each. When the pressure begins to drop, start the additional supply of acrylamide at 1.0 mL / min, reduce the KPS supply to 1.0 mL / min, and maintain the pressure by additional VDF supply. While continuing the supply in this manner, increase the acrylamide supply rate to relieve the instantaneous VDF supply demand and maintain a range of 500 - 1000 g / hour. Increase the acrylamide supply to 5.0 mL / min in this manner. Continue all supplies until a total of 700 g of VDF is supplied to the reactor. Stop the monomer supply, leave it for 10 minutes to allow the pressure to drop naturally, then vent the reactor to atmospheric pressure and cool it to room temperature. Drain the latex from the reactor and dry it overnight in a convection oven.

[0075] Example 6: Example (Vinylene Carbonate): Add 900 g of deionized water, 2.3 g of low molecular weight poly(acrylic acid) (BASF CP-10S), and 25 g of a 1.0 wt% vinylene carbonate aqueous solution to a 2-liter autoclave. Deoxygenate the autoclave by repeating the operation of pressurizing to 60 psi with nitrogen and then venting two or more times. Start stirring, heat the autoclave to 83 °C, and pressurize to 650 psi with vinylidene fluoride. Start the supply of 4.0 wt% potassium persulfate (KPS) at 5.0 mL / min each. When the pressure starts to drop, start the additional supply of vinylene carbonate at 1.0 mL / min, reduce the KPS supply to 1.0 mL / min, and maintain the pressure with an additional VDF supply. While continuing the supply in this manner, increase the vinylene carbonate supply rate to relieve the instantaneous VDF supply demand and maintain it in the range of 500 - 1000 g / hour. Increase the vinylene carbonate supply to 5.0 mL / min in this manner. Continue all supplies until a total of 700 g of VDF is supplied to the reactor. Stop the monomer supply, let it stand for 10 minutes to allow the pressure to drop naturally, then vent the reactor to atmospheric pressure and cool it to room temperature. Drain the latex from the reactor and dry it overnight in a convection oven.

[0076] Example 7: Example (Vinylene Carbonate): Add 900 g of deionized water, 2.3 g of low molecular weight poly(acrylic acid) (BASF CP-10S), and 25 g of a 1.0 wt% aqueous solution of carboxyethyl vinyl ether to a 2-liter autoclave. The autoclave is deoxygenated by repeating the operation of pressurizing to 60 psi with nitrogen and then evacuating two or more times. Start stirring, heat the autoclave to 83 °C, and pressurize to 650 psi with vinylidene fluoride. The supply of 4.0 wt% potassium persulfate (KPS) is started at 5.0 mL / min each. When the pressure starts to drop, start the additional supply of carboxyethyl vinyl ether at 1.0 mL / min, reduce the KPS supply to 1.0 mL / min, and maintain the pressure by additional VDF supply. While continuing the supply in this manner, increase the carboxyethyl vinyl ether supply rate to relieve the instantaneous VDF supply demand and maintain a range of 500 - 1000 g / hour. Increase the carboxyethyl vinyl ether supply to 5.0 mL / min in this manner. Continue all supplies until a total of 700 g of VDF is supplied to the reactor. Stop the monomer supply, leave it for 10 minutes to allow the pressure to drop naturally, then evacuate the reactor to atmospheric pressure and cool it to room temperature. Drain the latex from the reactor and dry it 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, 900 g of deionized water, 2.3 g of low molecular weight poly(acrylic acid) (BASF CP-10S), and 10 g of the AOE solution were added. The autoclave was deoxygenated by repeating the operation of pressurizing to 60 psi with nitrogen and then venting two or more times. Stirring was started, the autoclave was heated to 83 °C, and pressurized to 650 psi with vinylidene fluoride. The supply of 4.0 wt% potassium persulfate (KPS) was started at 5.0 mL / min respectively. When the pressure began to drop, an additional supply of AOE was started at 1.0 mL / min, the KPS supply was reduced to 1.0 mL / min, and the pressure was maintained by additional VDF supply. While continuing the supply in this manner, the AOE supply rate was increased to relieve the instantaneous VDF supply demand and maintained in the range of 500 - 1000 g / hour. The AOE supply was increased to 5.0 mL / min in this manner. All supplies were continued until a total of 700 g of VDF was supplied to the reactor. The monomer supply was stopped, left for 10 minutes to allow the pressure to drop naturally, 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 that the AOE solution concentration was increased to 4.0 wt% (12.0 g of AOE + 288.0 g of deionized water).

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

[0081] 900 g of deionized water, 2.3 g of low molecular weight poly(acrylic acid) (BASF CP-10S), and 10 g of the AOPD solution were added to a 2-liter autoclave. The autoclave was deoxygenated by repeating the operation of pressurizing to 60 psi with nitrogen and then venting two or more times. Stirring was started, the autoclave was heated to 83 °C, and pressurized to 650 psi with vinylidene fluoride. The supply of 4.0 wt% potassium persulfate (KPS) was started at 5.0 mL / min each. When the pressure began to drop, the additional supply of AOPD was started at 1.0 mL / min, the KPS supply was reduced to 1.0 mL / min, and the pressure was maintained by additional VDF supply. While continuing the supply in this manner, the AOPD supply rate was increased to relieve the instantaneous VDF supply demand and maintained in the range of 500 - 1000 g / hour. The AOPD supply was increased to 5.0 mL / min in this manner. All supplies were continued until a total of 700 g of VDF was supplied to the reactor. The monomer supply was stopped, left for 10 minutes to allow the pressure to drop naturally, 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 that the concentration of the KPS solution was reduced to 2.5 wt%.

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

[0084] To a 2-liter autoclave, 900 g of deionized water, 2.3 g of low molecular weight poly(acrylic acid) (BASF CP-10S), and 10 g of the AOPD solution were added. The autoclave was deoxygenated by repeating the operation of pressurizing to 60 psi with nitrogen and then venting two or more times. Stirring was started, the autoclave was heated to 83 °C, and pressurized to 650 psi with vinylidene fluoride. The supply of 4.0 wt% potassium persulfate (KPS) was started at 5.0 mL / min each. When the pressure began to drop, the additional supply of AA / AOE was started at 1.0 mL / min, the KPS supply was reduced to 1.0 mL / min, and the pressure was maintained by additional VDF supply. While continuing the supply in this manner, the AA / AOE supply rate was increased to relieve the instantaneous VDF supply demand and maintained in the range of 500 - 1000 g / hour. The AA / AOE supply was increased to 5.0 mL / min in this manner. All supplies were continued until a total of 700 g of VDF was supplied to the reactor. The monomer supply was stopped, left for 10 minutes to allow the pressure to drop naturally, 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 Manufacturing: The cathode slurry preparation procedure for laboratory scale is described here. First, the PVDF copolymer of the present invention is dissolved in an N-methylpyrrolidone (NMP) solvent, generally at a concentration of 5-10 wt%. To this binder solution, a conductive carbon additive, such as SuperP-Li obtained from Timcal, is added and mixed at 2000 rpm for 120 seconds 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 this mixture and generally mixed at 2000 rpm for 60 seconds to form a thick homogeneous paste. Then a small amount of NMP is added to this paste and mixed at 60 seconds / 2000 rpm to gradually reduce the solid content of the slurry (by about 1.5% for each addition of the NMP solution) and lower the viscosity. This dilution process is repeated multiple times until the viscosity of the slurry reaches a level suitable for coating (generally 3000-15000 cP @ 1 / sec shear rate). A typical formulation for the inventors' laboratory cathode is active material / carbon / PVDF = 97 / 1.5 / 1.5 (wt / wt / wt) on a dry basis.

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

[0087] The peel strength for the cathode was obtained by an ASTM D903 modified 180° peel test with three changes. The first change was that the tensile speed used was 50 mm / min (a peel speed of 25 mm / min). The second change was that no two-week conditioning period at the adjusted humidity and temperature was taken. The cathode was tested one day after manufacturing. The third change was that the cathode was adhered to the alignment plate using 3M's 401M paper double-sided tape, and the flexible aluminum foil current collector was peeled by the grips of the testing machine.

[0088]

Table 1

Claims

1. Fluorinated copolymer particles, wherein the monomer units of the copolymer particles consist of vinylidene fluoride and one or more hydrophilic monomers, the one or more hydrophilic monomers include a vinyl alkyl acid comonomer having the formula (M1), and the copolymer particles are in the form of particles having a size of 30 nm to 800 nm and do not have a fluorosurfactant, the fluorinated copolymer particles. 【Chemical Formula 1】 (wherein, R 1 、R 2 and R 3 are hydrogen; R 4 is a C 1 to C 16 linear alkylene group, branched alkylene group, or cyclic alkylene group; R 5 is carboxylic acid (C(O)OH), alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - NH 4 + ), alkylammonium carboxylate (COO - N(Alk) 4 + ), alcohol (OH), amide (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 - NH 4 + ), alkylammonium sulfonate (S(O)(O)O ammonium (S(O)(O)O - N(Alk) 4 + ).)

2. Fluorinated copolymer particles, wherein the monomer units of the copolymer particles consist of vinylidene fluoride and one or more non-fluorinated hydrophilic monomers, the hydrophilic monomer is a functional acrylamide comonomer, the functional acrylamide comonomer has the formula (M3), the copolymer particles are in the form of particles having a size of 30 nm to 800 nm, and the fluorinated copolymer particles do not have a fluorosurfactant. 【Chemical 2】 (wherein R 1 、R 2 and R 3 are hydrogen; R 4 and R 6 are each independently a C 1 - C 16 linear alkylene group, branched alkylene group, or cyclic alkylene group; R 5 and R 7 are each independently a carboxylic acid (C(O)OH), alkali metal carboxylate (COO - M + ), ammonium carboxylate (COO - NH 4 + ), alkylammonium carboxylate (COO - N(Alk) 4 + ), or phosphonate (P(O)(OH) 2 ), an alkali metal or ammonium phosphonate. )

3. Fluorinated copolymer particles, wherein the monomer units of the copolymer particles consist of vinylidene fluoride and one or more non-fluorinated hydrophilic monomers, the hydrophilic monomer is an allyloxy comonomer, has the formula (M6), the copolymer particles are in the form of particles having a size of 30 nm to 800 nm, and the fluorinated copolymer particles do not have a fluorosurfactant. 【Chemical 3】 (wherein, R 1 、R 2 and R 3is hydrogen; R 4 is CH 2 ; R 5 is C 1 ~ C 16 is a linear alkylene group, a branched alkylene group, or a cyclic alkylene group; R 6 is a carboxylic acid (C(O)OH), an alkali metal carboxylate (COO - M + ), an ammonium carboxylate (COO - NH 4 + ), an alkylammonium carboxylate (COO - N(Alk) 4 + ), an alcohol (OH), an amide (C(O)NH 2 ), a dialkylamide (C(O)NAlk 2 ), a sulfonic acid (S(O)(O)OH), an alkali metal sulfonate (S(O)(O)O - M + ), an ammonium sulfonate (S(O)(O)O - NH 4 + ), an alkylammonium sulfonate (S(O)(O)O - N(Alk) 4 + ), or a phosphonate (P(O)(OH) 2 ), an alkali metal or ammonium phosphonate.

4. The copolymer particles according to any one of claims 1 to 3, comprising up to 10.0% by weight of the hydrophilic monomer.

5. A method for producing the fluorinated copolymer particles according to any one of claims 1 to 3 in an aqueous reaction medium, a) forming an aqueous reaction medium comprising a stabilizer, vinylidene fluoride, and at least one hydrophilic monomer selected from the group consisting of vinyl alkyl acids having the formula (M1), functional acrylamides having the formula (M3), and allyloxy compounds having the formula (M6); b) Initiating the copolymerization of the vinylidene fluoride and the hydrophilic monomer by introducing at least one initiator, and carrying out the copolymerization under heat and superatmospheric pressure with stirring: including carrying out the polymerization at a temperature of 70 to 125 °C, carrying out the polymerization at a polymerization pressure of 2750 to 6900 kPa, the said method.

6. The method according to claim 5, wherein the aqueous reaction medium additionally contains at least one buffer.

7. The method according to claim 5 or 6, wherein the initiator is a persulfate or an organic peroxide.

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