Method for producing fluoropolymers

Abstract

The present invention is -SO3X a , -PO3X a , and -COOX a (X a is H, an ammonium group, or a monovalent metal), and a method for making a fluoropolymer dispersion therefrom. [Selection diagram] None

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to European Patent Application Publication No. 17161665.9, filed March 17, 2017, and European Patent Application Publication No. 17192376.6, filed September 21, 2017, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to a method for making a fluoropolymer dispersion using a particular multifunctional polymer derivative, and the fluoropolymer dispersion therefrom. [Background technology]

[0003] Fluoropolymers, i.e., polymers with a fluorinated backbone, have been known for a long time and have been used in a variety of applications due to several desirable properties such as heat resistance, chemical resistance, weather resistance, and UV stability.

[0004] A frequently used method for producing fluoropolymers involves the aqueous emulsion polymerization of one or more fluorinated monomers, which generally involves the use of fluorinated surfactants, including perfluorooctanoic acid and its salts, particularly ammonium perfluorooctanoate.

[0005] More recently, perfluoroalkanoic acids having 8 or more carbon atoms have raised environmental concerns. For example, they have been found to exhibit bioaccumulation. Thus, efforts are currently being made to phase out such compounds and to develop methods for producing fluoropolymer products using alternative surfactants with more favorable toxicity profiles.

[0006] Several approaches have been recently pursued towards this goal, typically involving fluorosurfactants that comprise perfluoroalkyl chains interrupted by one or more catenary oxygen atoms, said chains bearing an ionic carboxylate group at one of their termini.

[0007] Examples of these compounds having improved bioaccumulation profiles over perfluoroalkanoic acids having 8 or more carbon atoms can be found, inter alia, in US Patent Application Publication No. 2007276103 (3M INNOVATIVE PROPERTIES CO) 29 / 11 / 2007, US Patent Application Publication No. 2007015864 (3M INNOVATIVE PROPERTIES CO) 18 / 01 / 2007, US Patent Application Publication No. 2007015865 (3M INNOVATIVE PROPERTIES CO) 18 / 01 / 2007, US Patent Application Publication No. 2007015866 (3M INNOVATIVE PROPERTIES CO) 18 / 01 / 2007.

[0008] In general, all these approaches targeting alternative fluorinated surfactants that desirably exhibit lower bioaccumulation / biopersistence than perfluoroalkanoic acids with 8 or more carbon atoms may still involve the use of fluoro compounds, which may be highly fluorinated and / or may have a sufficiently low molecular weight such that they may be able to penetrate living cell membranes, and may nevertheless have a certain (bio)persistence.

[0009] Additional attempts have therefore been made to develop solutions using stabilizer / dispersant systems that are substantially free of such potentially harmful compounds, but which allow the polymerization to be carried out in a convenient, cost-effective manner, with reasonable productivity and acceptable latex stability, using the same equipment commonly used in the aqueous emulsion polymerization of fluorinated monomers with conventional surfactants.

[0010] EP 0341716A (ASAHI GLASS CO LTD) 15 / 11 / 1989 relates to a method for preparing an aqueous dispersion, which comprises emulsion polymerizing monomers in an aqueous medium in the presence of a fluorine-containing copolymer having a number average molecular weight of 1,000 to 500,000, in particular 3,000 to 400,000, which comprises units derived from fluoroolefins and units having hydrophilic side chains, the units having hydrophilic side chains having groups which may be (i) carboxylic acid groups or carboxylate groups of formula -COOM, (ii) sulfonic acid groups or sulfonate groups of formula -SO3M, and (iii) phosphonic acid groups or phosphonate groups of formula -PO3M, where M is hydrogen, an alkali metal, a quaternary ammonium group, or a quaternary phosphonium group, and (iv) an amide group. As the monomer, a fluoroolefin having 2 to 4 carbon atoms, such as hexafluoropropylene, pentafluoropropylene, tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, or vinylidene fluoride, and a vinyl compound, an allyl compound, a vinyl fluoride compound, or an allyl fluoride compound are preferred, since they produce an aqueous dispersion capable of imparting a coating layer having excellent weather resistance by polymerization. Summary of the Invention

[0011] Certain polyfunctional dispersing agents, detailed below, have been found to be effective in the aqueous emulsion polymerization of fluoromonomers, particularly tetrafluoroethylene and / or vinylidene fluoride, allowing for significant polymerization rates and providing stable dispersions, even when used without the addition of other surfactants, such as fluorinated surfactants.

[0012] Thus, in one aspect, the present invention relates to a process for the preparation of a fluoropolymer comprising the emulsion polymerization in an aqueous medium of one or more fluorinated monomers, said aqueous emulsion polymerization being carried out in an aqueous medium in the presence of at least one radical initiator and at least one multifunctional dispersing agent [dispersing agent (D)], said dispersing agent (D) being: - comprising a backbone chain containing repeat units derived from one or more ethylenically unsaturated monomers, - said dispersant (D) has a molecular weight and a molecular weight distribution such that it is substantially free of a fraction with a molecular weight below 3000; -SO3X in an amount of at least 1.75 meq / g based on the weight of the dispersant (D). a , -PO3X a , and -COOX a (X a is H, an ammonium group, or a monovalent metal; The dispersant (D) is used in an amount of 0.01% by weight and 5.00% by weight based on the total weight of the aqueous medium.

[0013] The applicant has surprisingly found that dispersant (D), despite its high molecular weight, has sufficient surface-active effect and dispersing ability to ensure efficient stabilization of fluoropolymer dispersion during polymerization due to the presence of an appropriate concentration of ionizable groups as pendant groups in fluorinated chains.In addition, although dispersant (D) residues may be contained in the fluoropolymer thus produced, due to its low volatility and high thermal stability, further processing of the fluoropolymer does not cause discoloration or foaming problems.

[0014] In the process for preparing a fluoropolymer, one or more dispersing agents (D) are used in the aqueous emulsion polymerization of one or more fluorinated monomers, in particular gaseous fluorinated monomers.

[0015] By gaseous fluorinated monomer is meant a monomer that exists as a gas under the polymerization conditions. In a particular embodiment, the polymerization of the fluorinated monomer is initiated in the presence of a dispersant (D). That is, the polymerization is initiated in its presence. The amount of dispersant (D) used can vary within the stated ranges depending on the desired properties such as the amount of solids, the conversion of the monomers, etc. Usually, the amount of dispersant (D) is at least 0.05% by weight, preferably at least 0.10% by weight, advantageously up to 4.00% by weight, preferably up to 3.50% by weight, more preferably up to 3.00% by weight, based on the total weight of the aqueous medium. A practical range is 0.15% by weight to 2.75% by weight, based on the total weight of the aqueous medium.

[0016] While the polymerization is usually initiated in the presence of dispersing agent (D), it is not excluded to add additional dispersing agent (D) during the polymerization, but this will not usually be necessary.

[0017] As explained above, the dispersant (D) is a polymer having a molecular weight and distribution thereof such that it is substantially free of any fraction having a molecular weight below 3000.

[0018] The determination of the substantial absence of fractions having a molecular weight less than 3000 can be accomplished using GPC techniques against polystyrene standards using dimethylacetamide as the eluent.

[0019] The term "substantially free" in relation to dispersant (D) and fractions having a molecular weight below 3000 is intended to mean that said fractions are not detectable by the GPC techniques detailed above.

[0020] The selection of a dispersant (D) that is substantially free of fractions having a molecular weight below 3000 is particularly advantageous in ensuring that the dispersant (D) has a toxicological profile such that it is unable to penetrate the membranes of living cells.

[0021] Generally, the dispersant (D) has a weight average molecular weight (M) of at least 10,000, preferably at least 15,000, as measured by GPC against polystyrene standards, usually using dimethylacetamide as the eluent. w ).

[0022] On the other hand, as long as the dispersant (D) has a certain amount of ionizable groups as described above that can give it sufficient dispersibility, the weight average molecular weight (M) of the dispersant (D) measured by GPC against polystyrene standards using dimethylacetamide as the eluent will be w The upper limit of is not particularly important.

[0023] However, it will be appreciated that the practical range of weight average molecular weight of the dispersant (D) is usually up to 1,000,000, preferably up to 600,000, more preferably up to 300,000.

[0024] Preferably, the dispersant (D) has a weight average molecular weight of at least 20,000, preferably at least 25,000, and / or advantageously at most 250,000, preferably at most 200,000.

[0025] Particularly good results were obtained with dispersants having a weight average molecular weight of 25,000 to 150,000.

[0026] As mentioned above, the dispersant (D) is -SO3X a , -PO3X a , and -COOX a and X comprises a plurality of ionizable groups selected from the group consisting of a is H, an ammonium group, or a monovalent metal. Preferably, the dispersant (D) is -SO3X a and COOX a and X comprises a plurality of ionizable groups selected from the group consisting of a is H, an ammonium group, or a monovalent metal.

[0027] The amount of said ionizable groups in dispersant (D) is usually at least 1.80, preferably at least 1.90, more preferably at least 2.00 meq / g based on the total weight of dispersant (D). Dispersants (D) with an amount of ionizable groups less than 1.75 meq / g are not polar enough to solubilize in the aqueous phase and produce a stabilizing / surfactant-like effect. There is no practical limit on the maximum amount of said ionizable groups contained in dispersant (D). It is usually understood that said ionizable groups are usually present in an amount of up to 2.50 meq / g, preferably up to 2.20 meq / g, more preferably up to 2.00 meq / g.

[0028] Dispersant (D) comprises said ionizable groups as pendant groups covalently attached to repeat units derived from an ethylenically unsaturated functional monomer, hereafter monomer (X).

[0029] The dispersant (D) may consist essentially of repeat units derived from one or more monomers (X) as detailed above, or may be a copolymer comprising repeat units derived from one or more monomers (X) and one or more additional monomers different to the monomers (X).

[0030] Typically, monomer (X) is a fluorinated monomer, and one or more additional monomers different from monomer (X) may also be fluorinated monomers. The expression "fluorinated monomer" is intended to encompass ethylenically unsaturated monomers containing at least one fluorine atom.

[0031] According to a particular embodiment of the invention, the dispersant (D) is a mixture of a plurality of -SO3X a The polymer containing the group, i.e. the dispersant (D SO3X ).

[0032] Dispersant (D SO3X ) is -SO3X a one or more ethylenically unsaturated functional monomers containing a group [monomer (X SO3X) ) , or may be composed essentially of repeat units derived from one or more monomers (X SO3X ) and monomer (X SO3X ), in particular one or more additional monomers different from the monomers (X SO3X ) and one or more additional repeat units derived from different fluorinated monomers.

[0033] A specific monomer (X SO3X The expression "repeating units derived from" in relation to one or more monomers (X) is intended to encompass repeating units derived / obtained directly from the polymerization of said particular monomers, as well as the corresponding repeating units derived / obtained from further modification / post-treatment thereof (e.g. hydrolysis). SO3X A dispersant containing a repeat unit derived from may be obtained, for example, by polymerizing a monomer containing a sulfonyl halide group and then hydrolyzing the polymer.

[0034] Multiple -SO3X a Suitable preferred dispersants containing the group (D SO3X ) is at least one -SO2X group (wherein X is a halogen (e.g., F) or -OX a and X a is as described above) (hereinafter, monomer (A)) and at least one ethylenically unsaturated fluorinated monomer not containing the -SO2X group (hereinafter, monomer (B)) described in detail above.

[0035] The phrase "at least one monomer" means that at least one of each type of monomer is a dispersant (D SO3X (A) and (B) monomers may be present in the reaction system. Hereinafter, the term "monomer" will be used to refer to both one and more than one monomer of the indicated type.

[0036] Non-limiting examples of suitable monomers (A) are: - Formula: CF2=CF(CF2) p SO2X (X is OX a (X a is as described above in detail), F, or Cl, preferably F, and p is an integer of 0 to 10, preferably 1 to 6, more preferably p is 2 or 3; - Formula: CF2=CF-O-(CF2) m SO2X (X is OX a (X a is as described above in detail), F, or Cl, preferably F, and m is an integer of 1 to 10, preferably 1 to 6, more preferably 2 to 4, and even more preferably m is 2); - Formula: CF2=CF-(OCF2CF(R F1 )) w -O-CF2(CF(R F2 )) y SO2X (X is OX a (X a is as described above), F, or Cl, preferably F; w is an integer of 0 to 2; R F1 and R F2 are equal to or different from each other and independently represent C1-C optionally substituted with F, Cl, or one or more ether oxygens; 10 is a fluoroalkyl group, y is an integer of 0 to 6; preferably, w is 1; R F1 is -CF3, y is 1, and R F2 is F); - Formula CF2 = CF-Ar-SO2X (X is OX a (X a is as detailed above), F, or Cl, preferably F; Ar is C 5~ C 15 halogenated sulfonyl aromatic fluoroolefins, It is.

[0037] Preferably, the monomer (A) has the formula CF2=CF-O-(CF2) m -SO2F (wherein m is an integer of 1 to 6, preferably 2 to 4),

[0038] More preferably, monomer (A) is CF2=CFOCF2CF2-SO2F (perfluoro-5-sulfonylfluoride-3-oxa-1-pentene).

[0039] Non-limiting examples of suitable ethylenically unsaturated fluorinated monomers of type (B) are: - C2-C8 perfluoroolefins such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoroisobutylene; - C2-C8 hydrogen-containing fluoroolefins such as trifluoroethylene (TrFE), vinylidene fluoride (VDF), vinyl fluoride (VF), pentafluoropropylene, and hexafluoroisobutylene; - C2-C8 chloro- and / or bromo- and / or iodo-containing fluoroolefins such as chlorotrifluoroethylene (CTFE) and bromotrifluoroethylene; - Formula CF2=CFOR f1 (In the formula, R f1 is C1-C6 fluoroalkyl, for example, -CF3, -C2F5, -C3F7) fluoroalkyl vinyl ether; - In particular, the formula CF2 = CFOCF2OR f2 Fluoromethoxyalkyl vinyl ether (R f2 is a C1-C3 fluoro(oxy)alkyl group, such as -CF2CF3, -CF2CF2-O-CF3, and -CF3. 12 fluorooxyalkyl vinyl ethers, - Formula: TIFF0007670460000001.tif39161 (in the formula, R f3 , R f4 , R f5 , and R f6 each of which is equal to or different from one another and is independently a fluorine atom, a C1-C6 fluoro(halo)fluoroalkyl optionally containing one or more oxygen atoms, e.g., -CF3, -C2F5, -C3F7, -OCF3, -OCF2CF2OCF3) fluorodioxole; It is.

[0040] Preferably, the monomer (B) is - C2 to C8 perfluoroolefins selected from tetrafluoroethylene (TFE) and / or hexafluoropropylene (HFP); - C2 to C8 hydrogen-containing fluoroolefins selected from trifluoroethylene (TrFE), vinylidene fluoride (VDF), and vinyl fluoride (VF); and - their mixture; is selected from.

[0041] According to these embodiments, preferably, a dispersant (D SO3X ) is a multiple of -SO3X a The fluorinated polymer comprises a repeating unit derived from at least one ethylenically unsaturated fluorinated monomer (A) containing at least one sulfonyl fluoride functional group, and at least one ethylenically unsaturated fluorinated monomer (B).

[0042] End groups, impurities, defects, and other pseudo-units in limited amounts (less than 1 mole % based on the total moles of repeating units) are considered to be dispersants (D SO3X ) may be present in the preferred polymer in addition to the recited repeat units without appreciably affecting the properties of the polymer.

[0043] According to a particular embodiment, the dispersant (D SO3X At least one monomer (B) of the dispersant (D) is TFE.SO3X ) is referred to herein as a dispersant (D TFE SO3X )

[0044] Preferred dispersants (D TFE SO3X )teeth, (1) A repeating unit derived from tetrafluoroethylene (TFE), which is a dispersant (D TFE SO3X ), a repeating unit usually in an amount of 50 to 99 mol %, preferably 50 to 98 mol %, based on the total number of moles of (2) (j) Formula: CF2=CF-O-(CF2) m SO2X (X is OX a (X a is as described above in detail), F, or Cl, preferably F, and m is an integer of 1 to 10, preferably 1 to 6, more preferably 2 to 4, and even more preferably m is 2); (jj) expression: CF2=CF-(OCF2CF(R F1 )) w -O-CF2(CF(R F2 )) y SO2X (X is OX a (X a is as described above), F, or Cl, preferably F; w is an integer of 0 to 2; R F1 and R F2 are equal to or different from each other and independently represent C1-C optionally substituted with F, Cl, or one or more ether oxygens; 10 is a fluoroalkyl group, y is an integer of 0 to 6; preferably, w is 1; R F1 is -CF3, y is 1, and R F2 is F); (jjj) their mixture; A repeating unit derived from at least one monomer selected from the group consisting of a dispersant (D TFESO3X ), the repeating unit being usually in an amount of 1 to 50 mol %, preferably 2 to 50 mol %, based on the total number of moles of (3) optionally, hexafluoropropylene, formula CF2=CFOR' f1 (In the formula, R' f1 is C1-C6 perfluoroalkyl, for example -CF3, -C2F5, -C3F7), perfluoroalkyl vinyl ether of the formula CF2=CFOR' O1 (In the formula, R' O1 For example, the formula CF2 = CFOCF2OR' f2 (In the formula, R' f2 is a C1-C6 perfluoroalkyl, for example, a C2-C6 perfluoroalkyl-methoxy-vinyl ether having one or more ether groups, such as -CF3, -C2F5, -C3F7, or a C1-C6 perfluorooxyalkyl having one or more ether groups (-C2F5-O-CF3, etc.). 12 at least one hydrogenated monomer and / or a fluorinated monomer different from TFE, preferably a perfluoromonomer, repeating units derived from the dispersant (D TFE SO3X a repeating unit which is usually present in an amount of 0 to 45 mol %, preferably 0 to 40 mol %, based on the total number of moles of The polymer is selected from the group consisting essentially of:

[0045] According to a particular embodiment, preferred dispersants (D TFE SO3X ) is usually (1) 50 to 95 mol %, preferably 55 to 93 mol %, of repeating units derived from TFE; (2) 5 to 50 mol %, preferably 7 to 45 mol %, of repeating units derived from the -SO2X group-containing monomer (2) described above in detail; (3) 0 to 25 mol %, preferably 0 to 20 mol %, of repeat units derived from a fluorinated monomer (3) other than TFE as described above; It essentially consists of:

[0046] According to certain other embodiments, the dispersant (D SO3X At least one monomer (B) of the dispersant (D) is VDF. SO3X ) is referred to herein as a dispersant (D VDF SO3X ) is called

[0047] Preferred dispersants (D VDF SO3X )teeth, (1) A repeating unit derived from vinylidene fluoride (VDF), which is a dispersant (D VDF SO3X ), a repeating unit which is usually present in an amount of 55 to 99 mol %, preferably 65 to 95 mol %, based on the total number of moles of (2) (j) Formula: CF2=CF-O-(CF2) m SO2X (X is OX a (X a is as described above in detail), F, or Cl, preferably F, and m is an integer of 1 to 10, preferably 1 to 6, more preferably 2 to 4, and even more preferably m is 2); (jj) expression: CF2=CF-(OCF2CF(R F1 )) w -O-CF2(CF(R F2 )) y SO2X (X is OX a (X a is as described above), F, or Cl, preferably F; w is an integer of 0 to 2; R F1 and R F2 are equal to or different from each other and independently represent C1-C optionally substituted with F, Cl, or one or more ether oxygens; 10 is a fluoroalkyl group, y is an integer of 0 to 6, and preferably w is 1; R F1 is -CF3, y is 1, and R F2is F); and (jjj) A mixture of these A repeating unit derived from at least one monomer selected from the group consisting of a dispersant (D VDF SO3X (a) a repeating unit, usually in an amount of 1 to 45 mol %, preferably 5 to 35 mol %, based on the total number of moles of (a); (3) Optionally, at least one repeat unit derived from a hydrogenated monomer or a fluorinated monomer other than VDF, which is a dispersant (D VDF SO3X a repeating unit which is usually present in an amount of 0 to 25 mol %, preferably 0 to 15 mol %, based on the total number of moles of The polymer is selected from the group consisting essentially of:

[0048] According to a particular embodiment, preferred dispersants (D VDF SO3X ) is usually - 55 to 95 mol %, preferably 60 to 92 mol %, of repeat units derived from VDF; (2) 5 to 45 mol %, preferably 8 to 40 mol %, of repeating units derived from the -SO2X group-containing monomer (2) described above in detail; (3) 0 to 15 mol %, preferably 0 to 10 mol %, of repeat units derived from the hydrogenated or fluorinated monomer (3) other than VDF as described above; It essentially consists of:

[0049] Dispersant (D SO3X ) can be prepared by any polymerization method known in the art. Suitable methods for the preparation of such polymers are, for example, those described in U.S. Pat. No. 4,940,525 (THE DOW CHEMICAL COMPANY) 10 / 07 / 1990, European Patent Application Publication No. 1323751A (SOLVAY SOLEXIS SPA) 02 / 07 / 2003, and European Patent Application Publication No. 1172382A (SOLVAY SOLEXIS SPA) 16 / 11 / 2002.

[0050] The aqueous emulsion polymerization may be carried out at a temperature of from 10° C. to 150° C., preferably from 20° C. to 130° C., and the pressure is typically from 2 to 60 bar, in particular from 5 to 45 bar.

[0051] The reaction temperature may be varied during the polymerization, for example to influence the molecular weight distribution, i.e. to obtain a broad molecular weight distribution or to obtain a bimodal or multimodal molecular weight distribution.

[0052] The pH of the polymerization medium may be in the range of pH 2-11, preferably 3-10, most preferably 4-10.

[0053] As mentioned above, the process of the present invention is carried out in an aqueous medium in the presence of at least one radical initiator, i.e. any initiator known for initiating the free radical polymerization of ethylenically unsaturated monomers. Suitable radical initiators include in particular peroxides and azo compounds as well as redox initiators. Specific examples of peroxide initiators include hydrogen peroxide, sodium or barium peroxide, diacyl peroxides such as diacetyl peroxide, disuccinyl peroxide, dipropionyl peroxide, dibutyryl peroxide, dibenzoyl peroxide, di-tert-butyl-peroxide, benzoylacetyl peroxide, diglutaric acid peroxide and dilauryl peroxide, and also peracids and their salts, for example ammonium, sodium or potassium salts. Examples of peracids include peracetic acid. Esters of peracids can be used as well, examples of which include tert.-butyl peroxyacetate and tert.-butyl peroxypivalate. Examples of inorganic initiators include, for example, ammonium, alkali, or alkaline earth salts of persulfuric acid, permanganic acid, or manganic acid, or manganic acid. Persulfate initiators, such as ammonium persulfate (APS), can be used alone or in combination with a reducing agent. Suitable reducing agents include bisulfites, such as ammonium bisulfite or sodium metabisulfite, thiosulfates, such as ammonium, potassium, or sodium thiosulfate, hydrazine, azodicarboxylates, and azodicarboxyldiamide (ADA). Additional reducing agents that can be used include sodium hydroxymethanesulfinate (Rongalite) or fluoroalkylsulfinates, such as those disclosed in U.S. Pat. No. 5,285,002. Reducing agents typically reduce the half-life of persulfate initiators. In addition, metal salt catalysts, such as, for example, copper, iron, or silver salts, may be added.

[0054] The amount of initiator may be from 0.01% by weight (based on the fluoropolymer produced) to 1% by weight, more preferably from 0.05 to 0.5% by weight, more preferably from 0.05 to 0.3% by weight, based on the fluoropolymer produced.

[0055] The aqueous emulsion polymerization can be carried out in the presence of other materials such as paraffin wax, buffers, and, if necessary, complex-forming or chain transfer agents.

[0056] Examples of chain transfer agents that can be used include dimethyl ether, methyl t-butyl ether, alkanes having 1 to 5 carbon atoms (such as ethane, propane, and n-pentane), halogenated hydrocarbons (such as CCl4, CHCl3, and CH2Cl2), and hydrofluorocarbon compounds such as CH2F-CF3 (R134a). Additionally, esters such as ethyl acetate and malonic acid esters may be effective as chain transfer agents in the process of the present invention.

[0057] Furthermore, the aqueous emulsion polymerization of the process of the present invention can be carried out in the presence of certain fluorinated fluids that are devoid of ionizable groups, typically allowing the formation of nano-sized droplets (average size less than 50 nm, preferably less than 30 nm), advantageously stabilized in the aqueous dispersion by the presence of a dispersing agent (D).

[0058] When the process of the invention is carried out in the presence of a fluorinated fluid, as detailed above, it may be preferred to first mix the dispersant (D) and said fluid homogeneously in an aqueous medium and then feed the aqueous mixture of dispersant (D) and said fluid thus obtained to the polymerization medium. This approach is particularly advantageous since this premix advantageously allows the preparation of an emulsion of said fluid in an aqueous phase containing dispersant (D), said emulsion comprising dispersed droplets of said fluid preferably having an average size of less than 50 nm, more preferably less than 40 nm and even more preferably less than 30 nm.

[0059] The fluids that can be used according to this embodiment are preferably (per)fluoropolyethers comprising a repeating unit (R1), said repeating unit comprising at least one ether bond and at least one fluorine atom in the main chain (fluoropolyoxyalkylene chain). Preferably, the repeating unit R1 of the (per)fluoropolyether is (I) -CF-O- (wherein X is -F or -CF); and (II) -CF2-CFX-O- (wherein X is -F or -CF3); and (III) -CF2-CF2-CF2-O-; and (IV) -CF2-CF2-CF2-CF2-O-; and (V)-(CF2) j -CFZ-O-, where j is an integer selected from 0 and 1, and Z is a fluoropolyoxyalkene chain containing 1 to 10 repeat units selected from classes (I) to (IV) herein above; and mixtures thereof. is selected from the group consisting of:

[0060] When the (per)fluoropolyether comprises different types of repeating units R1, advantageously said repeating units are randomly distributed along the fluoropolyoxyalkylene chain.

[0061] Preferably the (per)fluoropolyether has the following formula (Ip): T1-(CFX) p -OR f -(CFX) p’ -T2(Ip) [In the formula, - each X is independently F or CF3; - p and p' are equal or different and are integers from 0 to 3; - R f is a fluoropolyoxyalkene chain comprising a repeat unit R°, said repeat unit being (i) -CFXO- (wherein X is F or CF3), (ii) -CF2CFXO- (wherein X is F or CF3), (iii) -CF2CF2CF2O-, (iv) -CF2CF2CF2CF2O-, (v)-(CF2) j -CFZ-O-, where j is an integer selected from 0 and 1, and Z is a group of the general formula -OR f 'T3 group, R f ' is a fluoropolyoxyalkene chain containing 0 to 10 repeat units, said repeat units being selected from the group consisting of: each X is independently selected from among -CFXO-, -CF2CFXO-, -CF2CF2CF2O-, -CF2CF2CF2CF2O-, where each X is F or CF3; T3 is a C1-C3 perfluoroalkyl group), and mixtures thereof; - T1 and T2 are equal to or different from each other and are H, a halogen atom, or a C1-C3 fluoroalkyl group optionally containing one or more H or halogen atoms different from fluorine. It is a compound according to the following:

[0062] As previously mentioned, the process of the present invention involves emulsion polymerizing one or more fluorinated monomers.

[0063] The expression "fluorinated monomer" is intended in this specification to mean an ethylenically unsaturated monomer which contains at least one fluorine atom.

[0064] The fluorinated monomer may further contain one or more other halogen atoms (Cl, Br, I).

[0065] Non-limiting examples of suitable ethylenically unsaturated fluorinated monomers include: - C2-C8 perfluoroolefins such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoroisobutylene; - C2-C8 hydrogen-containing fluoroolefins such as trifluoroethylene (TrFE), vinylidene fluoride (VDF), vinyl fluoride (VF), pentafluoropropylene, and hexafluoroisobutylene; - C2-C8 chloro- and / or bromo- and / or iodo-containing fluoroolefins such as chlorotrifluoroethylene (CTFE) and bromotrifluoroethylene; - Formula CF2=CFOR f1 (In the formula, R f1 is C1-C6 fluoroalkyl, for example, -CF3, -C2F5, -C3F7) fluoroalkyl vinyl ether; - In particular, the formula CF2 = CFOCF2OR f2 Fluoromethoxyalkyl vinyl ether (R f2 is a C1-C3 fluoro(oxy)alkyl group, such as CF2CF3, -CF2CF2-O-CF3, and -CF3. 12 fluorooxyalkyl vinyl ethers, - Formula: TIFF0007670460000002.tif37161 (in the formula, R f3 , R f4 , R f5 , and R f6 each of which is equal to or different from one another and is independently a fluorine atom, a C1-C6 fluoro(halo)fluoroalkyl optionally containing one or more oxygen atoms, e.g., -CF3, -C2F5, -C3F7, -OCF3, -OCF2CF2OCF3) fluorodioxole; It is.

[0066] Preferred fluorinated monomers for use in the process of the present invention include tetrafluoroethylene (TFE), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), vinyl fluoride (VF), vinylidene fluoride (VDF), alone or in combination, or in combination with other monomers, most preferably TFE or VDF.

[0067] The process of the present invention may further include one or more fluorine-free ethylenically unsaturated monomers, also called "hydrogenated monomers". The selection of said hydrogenated comonomers is not particularly limited, and α-olefins, (meth)acrylic monomers, vinyl ether monomers, and styrene monomonomers can be used.

[0068] The method of the present invention can be used to produce a variety of fluoropolymers, such as perfluoropolymers with fully fluorinated backbones, as well as partially fluorinated fluoropolymers. The method of the present invention can also result in melt-processable fluoropolymers, as well as those that are not melt-processable, such as polytetrafluoroethylene and so-called modified polytetrafluoroethylene. The method of the present invention can further produce fluoropolymers that can be cured to produce fluoroelastomers and fluorothermoplasts. Fluorothermoplasts are generally fluoropolymers that have a well-defined and well-recognized melting point, typically in the range of 60°C to 320°C, or 100°C to 320°C. Thus, they have a substantial crystalline phase. Fluoropolymers used to produce fluoroelastomers are typically amorphous and / or have a negligible amount of crystallinity such that the melting point is not or barely discernible for these fluoropolymers.

[0069] The Applicant has found that the dispersing agent (D) is particularly effective for the preparation of thermoplastic vinylidene fluoride polymers by polymerization of vinylidene fluoride (VDF), optionally in combination with one or more hydrogenated monomers and / or fluorinated monomers different from VDF, and / or for the preparation of thermoplastic tetrafluoroethylene polymers by polymerization of tetrafluoroethylene (TFE), optionally in combination with one or more hydrogenated monomers and / or fluorinated monomers different from TFE.

[0070] Particularly good results have been obtained when the dispersants (D) according to the invention are used for the emulsion polymerization of TFE, either alone or in combination with one or more fluorinated monomers different from TFE.

[0071] Generally, the process of the present invention is carried out in the substantial absence of fluorinated emulsifiers having a molecular weight of less than 1000.

[0072] The term "substantially absent" when used in relation to fluorinated emulsifiers means that no surfactant is intentionally added to the polymerization. Impurities that may be considered fluorinated surfactants having molecular weights less than 1000 may be tolerated, but the amounts are usually below the detection limits of standard analytical techniques (less than 1 ppm for aqueous media).

[0073] More typically, the process of the present invention is carried out in the substantial absence of fluorinated emulsifiers having a molecular weight of less than 3000.

[0074] More specifically, the process of the present invention involves polymerization in an aqueous medium that is substantially free of fluorinated emulsifiers [surfactants (FS)] of the formula: R f§ (X - ) j (M + ) j (In the formula, R f§ is C3~C 30 (per)fluoroalkyl chain, (per)fluoro(poly)oxyalkylene chain, X - -COO - , -PO3 - , or -SO3 - And M + is H + , NH4 + , an alkali metal ion, and j can be 1 or 2).

[0075] Non-limiting examples of surfactants (FS) include ammonium and / or sodium (per)fluoro(oxy)carboxylates and / or (per)fluoropolyoxyalkylenes having one or more carboxyl end groups.

[0076] Examples of fluorinated surfactants, in particular (per)fluorooxyalkylene surfactants, are described in particular in US Patent Application Publication No. 2007015864 (3M INNOVATIVE PROPERTIES) 8 / 01 / 2007, US Patent Application Publication No. 2007015865 (3M INNOVATIVE PROPERTIES CO) 18 / 01 / 2007, US Patent Application Publication No. 2007015866 (3M INNOVATIVE PROPERTIES CO) 18 / 01 / 2007, US Patent Application Publication No. 2007025902 (3M INNOVATIVE PROPERTIES CO) 1 / 02 / 2007.

[0077] For example, fluorinated emulsifiers [surfactants (FS)] which are substantially excluded from the process of the present invention are in particular: - CF3 (CF2) n1 COOM' (wherein n1 is an integer ranging from 4 to 10, preferably from 5 to 7, more preferably 6; M' represents H, NH4, Na, Li, or K, preferably NH4); -T(C3F6O) n0 (CFXO) m0 CF2COOM″ (wherein T is Cl or k F 2k+1 represents a perfluoroalkoxide group of O, k is an integer of 1 to 3, and optionally one F atom may be replaced by a Cl atom; n0 is an integer ranging from 1 to 6; m0 is an integer ranging from 0 to 6; M″ represents H, NH4, Na, Li, or K; and X represents F or CF3); - F-(CF2-CF2) n2-CH2-CH2-RO3M''', where R is P or S, preferably S, M''' represents H, NH4, Na, Li, or K, preferably H; n2 is an integer ranging from 2 to 5, preferably n2=3; - AR f -B bifunctional fluorinated surfactant, where A and B are equal to or different from each other, -(O) p CFX-COOM * And;M * represents H, NH4, Na, Li, or K, preferably M * represents NH4; X=F or CF3; p is an integer equal to 0 or 1; R f AR f - B is a linear or branched perfluoroalkyl chain or (per)fluoropolyether chain such that the number average molecular weight of B is in the range of 300 to 1,000; - R' f -O-(CF2) r -OL-COOM' (where R' f is a linear or branched perfluoroalkyl chain, optionally containing a catenary oxygen atom; M' is H, NH4, Na, Li, or K, preferably M' represents NH4; r is 1 to 3; L is a divalent fluorinated bridging group, preferably -CF2CF2- or CFX-, with X=F or CF3); - R'' f -(OCF2) u -O-(CF2) v -COOM''(in the formula, R'' f is a linear or branched perfluoroalkyl chain optionally containing a catenary oxygen atom, M″ is H, NH4, Na, Li, or K, preferably M″ represents NH4; u and v are integers from 1 to 3; - R''' f -(O) t -CHQ-L-COOM''' (in the formula, R''' fis a linear or branched perfluoroalkyl chain optionally containing a catenary oxygen atom, Q=F or CF3, t is 0 or 1, M''' is H, NH4, Na, Li, or K, preferably M''' is NH4; L is a divalent fluorinated bridging group, preferably -CF2CF2- or CFX-, and X=F or CF3); - a cyclic fluorine compound of the following formula (I): TIFF0007670460000003.tif35161 (wherein X1, X2, and X3 are equal to or different from each other and independently represent H, F, and C which may optionally contain one or more catenary or non-catenary oxygen atoms). 1~6 (per)fluoroalkyl groups; L represents a bond or a divalent group; R F is divalent fluorinated C 1~3 is a bridging group; Y is a group of the formula TIFF0007670460000004.tif27161; X a is H, a monovalent metal (preferably an alkali metal) or a group of the formula -N(R' n ) 4 is an ammonium group, and R' n are equal or different in each occurrence and are a hydrogen atom or C 1~6 represents a hydrocarbon group) It is.

[0078] The process of the present invention typically results in an aqueous dispersion of a fluoropolymer which further contains a dispersing agent (D) as detailed above, which is another object of the present invention.

[0079] The present invention therefore relates to an aqueous dispersion of fluoropolymer particles containing at least one dispersant (D) as detailed above.

[0080] All preferred embodiments detailed above for the dispersant (D) and the fluoropolymer in connection with the process of the present invention are equally applicable to the aqueous dispersion of the present invention insofar as these features can be characterized in the same way.

[0081] The particle size (volume average diameter) of the fluoropolymer is typically from 40 nm to 400 nm, with typical particle sizes of 60 nm to about 350 nm being preferred.

[0082] The fluoropolymer may be isolated from the dispersion by coagulation if a solid form of the polymer is desired, and depending on the requirements of the application in which the fluoropolymer is to be used, the fluoropolymer may be subsequently fluorinated to convert any thermally unstable end groups to stable CF3- end groups.

[0083] For coating applications, an aqueous dispersion of the fluoropolymer is desired, and therefore the fluoropolymer would not need to be separated or coagulated from the dispersion. To obtain a fluoropolymer dispersion suitable for use in coating applications, such as in the impregnation of fabrics or in the coating of metal substrates, for example to produce cookware, it will generally be desirable to add additional stabilizing surfactants and / or further increase the fluoropolymer solids content. For example, non-ionic stabilizing surfactants may be added to the fluoropolymer dispersion. Typically, these will be added thereto in amounts of 1-12% by weight based on the fluoropolymer solids content. Examples of non-ionic surfactants that may be added include R 1 -O-[CH2CH2O] n -[R 2 O] m -R 3 (NS)(wherein, R 1 represents an aromatic or aliphatic hydrocarbon group having 6 to 18 carbon atoms, R 2 represents an alkylene group having 3 carbon atoms, R 3 is hydrogen or C 1~3represents an alkyl group, n has a value of 0-40, m has a value of 0-40, and the sum of n+m is at least 2). It will be understood that in the above formula (NS), the units indexed by n and m may appear as blocks, or they may be present in alternating or random configuration. Examples of nonionic surfactants according to the above formula (NS) include, for example, TRITON, in which the number of ethoxy units is about 10. TM X 100 or TRITON with about 7-8 ethoxy units TM X114 and other brand names TRITON TM Still further examples include alkylphenol oxyethylates such as ethoxylated p-isooctylphenol, which is commercially available at 1 represents an alkyl group having 4 to 20 carbon atoms, m is 0, and R 3 where R is hydrogen. An example is isotridecanol ethoxylated with about 8 ethoxy groups, which is commercially available as GENAPOL® X080 from Clariant GmbH. Nonionic surfactants according to formula (NS) in which the hydrophilic part comprises a block copolymer of ethoxy and propoxy groups may be used as well. Such nonionic surfactants are commercially available under the trade names GENAPOL® PF 40 and GENAPOL® PF 80 from Clariant GmbH.

[0084] The amount of fluoropolymer solids in the dispersion may be concentrated as necessary or desired to an amount of 30-70% by weight. Any known concentration technique may be used, such as ultrafiltration and thermal concentration.

[0085] To the extent that the disclosures of any patents, patent applications, and publications incorporated herein by reference conflict with the statements of this application to the extent that the term may be unclear, this statement shall control.

[0086] The invention will now be described in more detail hereinafter with reference to the following examples, the purpose of which is merely illustrative and is not intended to limit the scope of the invention. EXAMPLES

[0087] Preparation Example 1 - Preparation of Dispersant (D-1) by Polymerization of Tetrafluoroethylene (TFE) and Perfluoro-5-sulfonylfluoride-3-oxa-1-pentene (SFVE) and Subsequent Hydrolysis

[0088] Step 1-Polymerization The following reagents were placed in a 5 L autoclave: - 1.9L demineralized water - Formula: CF2=CF-O-CF2CF2-SO2F (SFVE) monomer 185g - Formula: 500 g of a 46 wt.% aqueous solution of the ammonium salt of the fluoro compound (Xa is NH4) of TIFF0007670460000005.tif35161. The autoclave, stirred at 650 rpm, was heated to 65 °C. An aqueous solution of potassium persulfate at 16 g / L was added in an amount of 90 mL. The pressure was maintained at a value of 10 bar (abs.) by feeding tetrafluoroethylene (TFE) at 4 bar pf, CO2 at 5.5 bar, and ethane at 0.1 bar. After adding 68 g of tetrafluoroethylene to the reactor, 40 g of monomeric SFVE were fed to the autoclave. A further 22 g of tetrafluoroethylene was added to the reactor, followed by the addition of 55 g of monomeric SFVE for every 22 g of tetrafluoroethylene consumed by the reaction. The reaction was stopped after 540 min by stopping the stirring, cooling the autoclave, degassing the TFE and reducing the pressure, and a total of 450 g of TFE was fed to the autoclave. A copolymer was obtained containing about 2.2 eq / g of sulfonyl fluoride groups and having the following composition: TFE; 63.3 mol%; SFVE: 36.7 mol% (determined by NMR measurements). A weight average molecular weight of 95000 was obtained from GPC measurements performed against polystyrene standards in dimethylacetamide as solvent. Fractions with molecular weights below 3000 were practically not detected by GPC.

[0089] Step 2 - Hydrolysis and purification The latex obtained in step 1 was degassed overnight with a stream of nitrogen to remove monomer residues, placed in a stirred glass vessel and heated at 90° C. under gentle stirring. An aqueous solution of NaOH (5% concentrated) was added dropwise until a molar amount of NaOH corresponding to 20% of the -SO2F groups present in the polymer was reached. After 30 minutes, additional NaOH was added so that the molar ratio between the equivalent of NaOH added and the total amount of SO2F groups present in the polymer was 4:1. The solution thus obtained was kept at 90° C. for 1 hour under gentle stirring. No coagulum was formed during the entire process.

[0090] A sample of the solution was dried overnight in a ventilated oven and the solid residue was characterized by infrared spectroscopy to confirm that all SO2F groups originally contained in the dispersant precursor had been converted to -SO3Na groups. No sign of residual SO2F was detected. The solution, cooled to ambient temperature, was loaded onto a column containing the resin Dowex Monosphere® 650C UPW, pretreated with 1M nitric acid, and washed with demineralized water to remove the cations, especially the excess Na + cations) and the SO3Na groups of the dispersant (D-1) were converted to -SO3H groups. In the next step, the solution of dispersant (D-1) so obtained was fed to a second column containing Dowex Monosphere® 550A pretreated with 1M NaOH and washed with demineralized water to remove the fluorides generated by -SO2F conversion and other anionic species present in the dispersion (such as anionic sites of fluorosurfactants). After these treatments, the pH of the solution was found to be about 2. Dilute NaOH was added dropwise to reach a neutral pH, resulting in the conversion of the -SO3H groups of the dispersant (D-1) to -SO3Na groups.

[0091] ICP analysis showed the absence of cations other than Na, and liquid chromatography analysis showed the absence of fluoride or other anionic species. A reverse osmosis system was used to concentrate the aqueous solution of dispersant (D-1) to a solids content of 15%. The result was completely stable (no coagulum).

[0092] Polymerization Example 2: Polymerization of Tetrafluoroethylene (TFE) in the Presence of Dispersant (D-1) The following reagents were placed in a 5 L autoclave: - 2.0L demineralized water; 150 g of a 15% by weight aqueous solution of dispersant (D-1) obtained from Preparation Example 1 (i.e. corresponding to 22.5 g of dispersant (D-1)), resulting in a concentration of about 1.12% based on the aqueous phase.

[0093] The autoclave, stirred at 500 rpm, was heated to 80° C. An aqueous solution of 6 g / L potassium persulfate was added in an amount of 15 mL. The pressure was maintained at a value of 12.4 bar (abs.) by feeding tetrafluoroethylene (TFE).

[0094] The pressure of the autoclave was maintained at a constant value of 12.4 bar by feeding TFE until an amount of 600 g of TFE was fed, after 182 minutes the feeding of TFE was stopped. The autoclave was cooled to ambient temperature by maintaining a constant stirring of 500 rpm and kept under nitrogen bubbling for 16 hours to remove residual monomers from the polymerization, after which the latex was removed and stored in a plastic tank. No sign of coagulation / precipitation of the latex was observed. The PTFE dispersion thus produced was characterized by laser light scattering to determine the average particle size, which was found to be 72 nm.

[0095] The PTFE thus formed was cryogenically coagulated and dried. NMR analysis of a sample of the aqueous liquid separated from the coagulate showed no detectable traces of dispersant (D-1), leading to the conclusion that the dispersant (D-1) remains trapped within the coagulated PTFE. The PTFE was analyzed by DSC, revealing a ΔH f is 47.98 J / g, and T f was found to be 329.89 °C. These two properties are determined in the second heating cycle according to ASTM D3418.

[0096] Comparative Example 3: Polymerization of Tetrafluoroethylene (TFE) Using Prior Art Fluorinated Surfactants The following reagents were placed in a 5 L autoclave: - 2.0L demineralized water; - Formula: TIFF0007670460000006.tif35161(X a38 g of a 46% by weight aqueous solution of the ammonium salt of the fluoro compound (NH4), corresponding to a concentration of approximately 0.9% based on the aqueous phase.

[0097] The autoclave, stirred at 500 rpm, was heated to 80° C. An aqueous solution of 6 g / L potassium persulfate was added in an amount of 15 mL. The pressure was maintained at a value of 12.4 bar (abs.) by feeding tetrafluoroethylene (TFE).

[0098] The pressure of the autoclave was maintained at a constant value of 12.4 bar by feeding TFE until an amount of 600 g of TFE was fed, after 300 min the TFE feed was stopped. The autoclave was cooled to ambient temperature by maintaining a constant stirring of 500 rpm and kept under nitrogen bubbling for 16 h to remove residual monomers from the polymerization, after which the latex was removed and then stored in a plastic tank. No signs of coagulation / precipitation of the latex were observed.

[0099] The PTFE dispersion so produced was characterized by laser light scattering to determine the average particle size and found to be 134 nm, which is significantly larger than the size of the dispersion of Example 2, clearly demonstrating the effectiveness of dispersing agent (D) in forming fine, isolated emulsion polymerization sites.

[0100] When PTFE was analyzed by DSC, ΔH f is 46.07 J / g, and T f was found to be 329.14° C. These two properties were determined in a second heating cycle according to ASTM D3418, leading to the conclusion that the PTFE materials obtained from Example 2 and Example 3C have essentially the same properties, including substantially the same molecular weight.

Claims

1. A process for the preparation of a fluoropolymer comprising emulsion polymerizing one or more fluorinated monomers in an aqueous medium, the aqueous emulsion polymerization being carried out in an aqueous medium in the presence of at least one radical initiator and at least one multifunctional dispersing agent [dispersing agent (D)], the dispersing agent (D) being: - comprises a backbone chain comprising repeat units derived from one or more ethylenically unsaturated monomers, the dispersant (D) has a molecular weight and a distribution thereof such that it is substantially free of any fraction with a molecular weight below 3000, in an amount of at least 1.75 meq / g relative to the weight of the dispersant (D), ３ X ａ (X ａ is H, an ammonium group, or a monovalent metal; The amount of dispersant (D) is at least 0.05% by weight and at most 4.00% by weight, based on the total weight of the aqueous medium; The dispersant (D) is (i) (1) Repeating units derived from tetrafluoroethylene (TFE), the repeating units being present in an amount of 50 to 99 mol % based on the total number of moles of the dispersant (D); and (2) Repeating units derived from halogenated sulfonyl fluorovinyl ethers of the formula: CF 2 ═CF—O—(CF 2 ) m SO 2 X, where X is OX a (where X a is as defined above) and m is an integer from 1 to 10, in an amount of 1 to 50 mol % based on the total number of moles of dispersant (D). or a polymer consisting of (ii) (1) Repeating units derived from vinylidene fluoride (VDF), the repeating units being present in an amount of 55 to 99 mol % based on the total number of moles of the dispersant (D); and (2) Repeating units derived from halogenated sulfonyl fluorovinyl ethers of the formula: CF 2 ═CF—O—(CF 2 ) m SO 2 X, where X is OX a (where X a is as defined above) and m is an integer from 1 to 10, in an amount of 1 to 45 mol % based on the total number of moles of dispersant (D). A polymer consisting of A method selected from the group consisting of

2. The dispersant (D) has a weight average molecular weight (M) of at least 10,000 and / or at most 1,000,000 as measured by GPC. ｗ 2. The method of claim 1 , comprising:

3. 3. The method according to claim 1 or 2, wherein the amount of ionizable groups in the dispersant (D) is at least 1.80 and / or at most 2.50 meq / g relative to the weight of the dispersant (D).

4. The method according to claim 1, wherein the aqueous emulsion polymerization is carried out at a temperature between 10°C and 150°C and / or at a pressure between 2 and 60 bar.

5. A method according to any one of claims 1 to 4, wherein the radical initiator is selected from peroxides and azo compounds and redox initiators, and / or the amount of initiator is 0.01% by weight to 1% by weight (based on the fluoropolymer produced).

6. The method of claim 1, wherein the aqueous emulsion polymerization is carried out in the presence of a fluorinated fluid lacking ionizable groups.

7. the fluorinated fluid is selected from the group consisting of (per)fluoropolyethers comprising repeating units (R1) (fluoropolyoxyalkylene chains) containing at least one ether bond and at least one fluorine atom in the main chain; The repeating unit R1 of the (per)fluoropolyether is (I) -CFX-O- (wherein X is -F or -CF ３ (wherein (II) -CF ２ -CFX-O- (wherein X is -F or -CF ３ (wherein (III)-CF ２ -CF ２ -CF ２ -O-; and (IV)-CF ２ -CF ２ -CF ２ -CF ２ -O-; and (V)-(CF ２ ) ｊ -CFZ-O-, where j is an integer selected from 0 and 1, and Z is a fluoropolyoxyalkene chain containing 1 to 10 repeat units selected from classes (I) to (IV) above; and mixtures thereof; The method of claim 6, wherein the compound is selected from the group consisting of:

8. - C such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP), and perfluoroisobutylene ２ ~C ８ Perfluoroolefin; C such as trifluoroethylene (TrFE), vinylidene fluoride (VDF), vinyl fluoride (VF), pentafluoropropylene and hexafluoroisobutylene ２ ~C ８ hydrogen-containing fluoroolefins; - C such as chlorotrifluoroethylene (CTFE) and bromotrifluoroethylene ２ ~C ８ Chloro-, and / or bromo-, and / or iodo-containing fluoroolefins; - Formula CF ２ =CFOR ｆ１ (In the formula, R ｆ１ is C １ ~C ６ Fluoroalkyl, such as -CF ３ , -C ２ F ５ , -C ３ F ７ Fluoroalkyl vinyl ethers of the formula: In particular of the formula CF ２ = CFOCF ２ OR ｆ２ Fluoromethoxyalkyl vinyl ether (R ｆ２ is -CF ２ CF ３ , -CF ２ CF ２ -O-CF ３ , and -CF ３ Such as C １ ~C ３ CF, which is a fluoro(oxy)alkyl group. ２ =CFOX ０ (In the formula, X ０ is a C group containing one or more ethereal oxygen atoms １ ~C １２ fluorooxyalkyl vinyl ethers, - Formula: (In the formula, R ｆ３ , R ｆ４ , R ｆ５ , and R ｆ６ are equal to or different from each other, and independently each independently represent a C which optionally contains a fluorine atom, one or more oxygen atoms. １ ~C ６ Fluoro(halo)fluoroalkyl, such as -CF ３ , -C ２ F ５ , -C ３ F ７ , -OCF ３ , -OCF ２ CF ２ O.C.F. ３ Fluorodioxoles of the formula: The method of any one of claims 1 to 7, comprising polymerizing one or more fluorinated monomers selected from the group consisting of:

Images