The invention pertains to a process for manufacturing a (per)fluoropolymer, said process comprising polymerizing one or more fluorinated monomers in the presence of a multi-phase medium, said medium comprising: (A) a water phase [phase (W)]; (B) at least one fluorinated surfactant [surfactant (FS)] having formula (I) here below:
R.sub.f—(OCF.sub.2CF.sub.2).sub.k-1—O—CF.sub.2—COOX.sub.a  (I) wherein R.sub.f is a C.sub.1-C.sub.3 perfluoroalkyl group comprising, optionally, one or more ether oxygen atoms, k is 2 or 3 and X.sub.a is a selected from a monovalent metal and an ammonium group of formula NR.sup.N.sub.4, wherein R.sup.N, equal or different at each occurrence, is a hydrogen atom or a C.sub.1-C.sub.3 alkyl group; (C) an oil phase [phase (O)] comprising: at least one non-functional (per)fluoropolyether (non-functional PFPE) comprising at least one (per)fluoropolyoxyalkylene chain [chain (R.sub.F)] and at least one functional (per)fluoropolyether (functional PFPE) comprising at least one (per)fluoropolyoxyalkylene chain [chain (R′.sub.F)] and having a number average molecular weight of at least 1000 and a solubility of less than 1% by weight in water at 25° C.

The invention pertains to a process for manufacturing a (per)fluoropolymer, said process comprising polymerizing one or more fluorinated monomers in the presence of a multi-phase medium, said medium comprising: (A) a water phase [phase (W)]; (B) at least one fluorinated surfactant [surfactant (FS)] having formula (I) here below:
R.sub.f—(OCF.sub.2CF.sub.2).sub.k-1—O—CF.sub.2—COOX.sub.a  (I) wherein R.sub.f is a C.sub.1-C.sub.3 perfluoroalkyl group comprising, optionally, one or more ether oxygen atoms, k is 2 or 3 and X.sub.a is a selected from a monovalent metal and an ammonium group of formula NR.sup.N.sub.4, wherein R.sup.N, equal or different at each occurrence, is a hydrogen atom or a C.sub.1-C.sub.3 alkyl group; (C) an oil phase [phase (O)] comprising: at least one non-functional (per)fluoropolyether (non-functional PFPE) comprising at least one (per)fluoropolyoxyalkylene chain [chain (R.sub.F)] and at least one functional (per)fluoropolyether (functional PFPE) comprising at least one (per)fluoropolyoxyalkylene chain [chain (R′.sub.F)] and having a number average molecular weight of at least 1000 and a solubility of less than 1% by weight in water at 25° C.

An object of the present invention is to provide a redox flow secondary battery being low in the electric resistance and excellent in the current efficiency as well, and further having the durability. The present invention relates to an electrolyte membrane for a redox flow secondary battery, the electrolyte membrane containing an ion-exchange resin composition containing a fluorine-based polyelectrolyte polymer, and having an ion cluster diameter of 1.00 to 2.95 nm as measured in water at 25° C. by a small angle X-ray method, and to a redox flow secondary battery using the electrolyte membrane.

An object of the present invention is to provide a redox flow secondary battery being low in the electric resistance and excellent in the current efficiency as well, and further having the durability. The present invention relates to an electrolyte membrane for a redox flow secondary battery, the electrolyte membrane containing an ion-exchange resin composition containing a fluorine-based polyelectrolyte polymer, and having an ion cluster diameter of 1.00 to 2.95 nm as measured in water at 25° C. by a small angle X-ray method, and to a redox flow secondary battery using the electrolyte membrane.

A compound having a group represented by the formula (Ia): ##STR00001##
wherein R.sup.1 represents a C.sub.1 to C.sub.8 fluorinated alkyl group, R.sup.2 represents a group having an optionally substituted C.sub.5 to C.sub.18 alicyclic hydrocarbon group, and * represents a binding site.

A compound having a group represented by the formula (Ia): ##STR00001##
wherein R.sup.1 represents a C.sub.1 to C.sub.8 fluorinated alkyl group, R.sup.2 represents a group having an optionally substituted C.sub.5 to C.sub.18 alicyclic hydrocarbon group, and * represents a binding site.

A method for producing a binder composition for a storage battery device, which comprises an emulsion polymerization step of emulsion polymerizing a monomer mixture containing a fluorinated vinyl monomer in the presence of a first anionic emulsifying agent (A), an aqueous medium and a radical polymerization initiator to obtain a latex containing a fluorinated polymer, and a post addition step of adding a second anionic emulsifying agent (B) to the latex. The first anionic emulsifying agent (A) has no phenyl group in its molecule, and the second anionic emulsifying agent (B) has a phenyl group in its molecule.

A method for producing a binder composition for a storage battery device, which comprises an emulsion polymerization step of emulsion polymerizing a monomer mixture containing a fluorinated vinyl monomer in the presence of a first anionic emulsifying agent (A), an aqueous medium and a radical polymerization initiator to obtain a latex containing a fluorinated polymer, and a post addition step of adding a second anionic emulsifying agent (B) to the latex. The first anionic emulsifying agent (A) has no phenyl group in its molecule, and the second anionic emulsifying agent (B) has a phenyl group in its molecule.

The invention pertains to a method for making a fluoropolymer comprising an aqueous emulsion polymerization of one or more fluorinated monomers wherein said aqueous emulsion polymerization is carried out in the presence of at least one cyclic fluorocompound of the following formula (I): ##STR00001##
wherein X.sub.1, X.sub.2, X.sub.3, equal or different from each other are independently selected among H, F, and C.sub.1-6 (per)fluoroalkyl groups, optionally comprising one or more catenary or non-catenary oxygen atoms; L represents a bond or a divalent group; R.sub.F is a divalent fluorinated C.sub.1-3 bridging group; Y is a hydrophilic function selected among anionic functionalities, cationic functionalities and non-ionic functionalities.

The invention pertains to a method for making a fluoropolymer comprising an aqueous emulsion polymerization of one or more fluorinated monomers wherein said aqueous emulsion polymerization is carried out in the presence of at least one cyclic fluorocompound of the following formula (I): ##STR00001##
wherein X.sub.1, X.sub.2, X.sub.3, equal or different from each other are independently selected among H, F, and C.sub.1-6 (per)fluoroalkyl groups, optionally comprising one or more catenary or non-catenary oxygen atoms; L represents a bond or a divalent group; R.sub.F is a divalent fluorinated C.sub.1-3 bridging group; Y is a hydrophilic function selected among anionic functionalities, cationic functionalities and non-ionic functionalities.