Copolymers of one or more halogenated olefins and one or more halogenated co-monomers selected from the group consisting of halogenated alkenyl ethers, halogenated alkenyl esters, and halogenated (meth)acrylates are useful in various end-use applications wherein the presence of halogen (e.g., fluorine) in the copolymer imparts one or more desirable properties, as compared to analogous copolymers not containing halogen.

A polymer composition of cross-linked fluoropolymers is provided, that is generated using a fluoropolymer compatibilizer. The cross-linked fluoropolymers have excellent mechanical and dielectric characteristics at high temperatures, making them useful for such applications as insulation for automotive communications cables and PCB laminates.

The copolymer includes divalent units represented by formula —[CF.sub.2—CF.sub.2]—, divalent units represented by formula; and one or more divalent units independently represented by formula: The copolymer has an —SO.sub.2X equivalent weight in a range from 300 to 2000. A polymer electrolyte membrane that includes the copolymer and a membrane electrode assembly that includes such a polymer electrolyte membrane are also provided.

A water repellent composition comprising a fluorinated copolymer having structural units based on a monomer (a) having a C.sub.1-6 polyfluoroalkyl group, structural units based on a monomer (b) having a C.sub.1-6 alkyl group and structural units based on a monomer (c) (halogenated olefin), and a medium, wherein the proportion of the structural units based on the monomer (a) is from 50 to 90 mass % of the structural units (100 mass %) based on all the monomers.

To provide a membrane/electrode assembly excellent in the power generation characteristics in a wide temperature range and a wide humidity range; an electrolyte material suitable for a catalyst layer of the membrane/electrode assembly; and a liquid composition suitable for forming a catalyst layer of the membrane/electrode assembly.

To use an electrolyte material which is formed of a polymer (H) obtained by converting precursor groups in a polymer (F) having structural units (A) based on a perfluoromonomer having a precursor group represented by the formula (g1), structural units (B) represented by the formula (u2), and structural units (C) based on tetrafluoroethylene, wherein the proportion of the structural units (A) is from 8 to 19 mol %, the proportion of the structural units (B) is from 65 to 80 mol %, and the proportion of the structural units (C) is from 1 to 27 mol %, to ion exchange groups.

##STR00001##

The fluorine-containing copolymer of the present invention includes: a structural unit (A) represented by the following formula (1); and at least one selected from the group consisting of a structural unit (B) represented by the following formula (2), a structural unit (C) represented by the following formula (3), and a structural unit (D) represented by the following formula (4):

##STR00001##

in the formula (1), R.sub.ff.sup.1 to R.sub.ff.sup.4 each independently represent a fluorine atom, a perfluoroalkyl group having 1 to 7 carbon atoms, or a perfluoroalkyl ether group having 1 to 7 carbon atoms, and R.sub.ff.sup.1 and R.sub.ff.sup.2 are optionally linked to form a ring;

##STR00002##

in the formula (2), R.sup.1 to R.sup.3 each independently represent a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms, R.sup.4 represents a perfluoroalkyl group having 1 to 7 carbon atoms, the perfluoroalkyl group optionally has a ring structure, one or some of the fluorine atoms are optionally substituted by a halogen atom other than a fluorine atom, and one or some of fluorine atoms in the perfluoroalkyl group are optionally substituted by a halogen atom other than a fluorine atom;

##STR00003##

in the formula (3), R.sup.5 to R.sup.8 each independently represent a fluorine atom or a perfluoroalkyl group having 1 to 7 carbon atoms, the perfluoroalkyl group optionally has a ring structure, one or some of the fluorine atoms are optionally substituted by a halogen atom other than a fluorine atom, and one or some of fluorine atoms in the perfluoroalkyl group are optionally substituted by a halogen atom other than a fluorine atom; and

##STR00004##

in the formula (4), Z represents an oxygen atom, a single bond, or —OC(R.sup.19R.sup.20)O—, R.sup.9 to R.sup.20 each independently represent a fluorine atom, a perfluoroalkyl group having 1 to 5 carbon atoms, or a perfluoroalkoxy group having 1 to 5 carbon atoms, one or some of the fluorine atoms are optionally substituted by a halogen atom other than a fluorine atom, one or some of fluorine atoms in the perfluoroalkyl group are optionally substituted by a halogen atom other than a fluorine atom, one or some of fluorine atoms in the perfluoroalkoxy group are optionally substituted by a halogen atom other than a fluorine atom, s and t are each independently 0 to 5, and s+t represents an integer of 1 to 6 (when Z is —OC(R.sup.19R.sup.20)O—, s+t is optionally 0).

To provide a method for producing a fluorinated polymer which does not require an emulsifier as an essential component while an aqueous medium with little environmental burden is used.

A method for producing a fluorinated polymer, which comprises polymerizing at least one fluorinated monomer selected from tetrafluoroethylene, chlorotrifluoroethylene and vinylidene fluoride, in an aqueous medium in the presence of a first polymer having units based on a compound represented by the following formula (1):

CXY═CR.sup.1-L-R.sup.2  (1)

wherein X and Y are each independently a hydrogen atom, a halogen atom or a methyl group, R.sup.1 is a hydrogen atom, a halogen atom or a C.sub.1-3 alkyl group, L is —CO—O—*, —O—CO—* or —O—, provided that * represents the binding position to R.sup.2, and R.sup.2 is a cyclic alkyl group, a monovalent aromatic hydrocarbon group or a C.sub.1-6 linear alkyl group, provided that the C.sub.1-6 linear alkyl group as R.sup.2 may have an etheric oxygen atom in a carbon-carbon bond, and the hydrogen atom in the cyclic alkyl group, the monovalent aromatic hydrocarbon group or the C.sub.1-6 linear alkyl group as R.sup.2 may be replaced with a halogen atom.

To provide a method for producing a fluorinated polymer which does not require an emulsifier as an essential component while an aqueous medium with little environmental burden is used.

A method for producing a fluorinated polymer, which comprises polymerizing at least one fluorinated monomer selected from tetrafluoroethylene, chlorotrifluoroethylene and vinylidene fluoride, in an aqueous medium in the presence of a first polymer having units based on a compound represented by the following formula (1):

CXY═CR.sup.1-L-R.sup.2  (1)

wherein X and Y are each independently a hydrogen atom, a halogen atom or a methyl group, R.sup.1 is a hydrogen atom, a halogen atom or a C.sub.1-3 alkyl group, L is —CO—O—*, —O—CO—* or —O—, provided that * represents the binding position to R.sup.2, and R.sup.2 is a cyclic alkyl group, a monovalent aromatic hydrocarbon group or a C.sub.1-6 linear alkyl group, provided that the C.sub.1-6 linear alkyl group as R.sup.2 may have an etheric oxygen atom in a carbon-carbon bond, and the hydrogen atom in the cyclic alkyl group, the monovalent aromatic hydrocarbon group or the C.sub.1-6 linear alkyl group as R.sup.2 may be replaced with a halogen atom.

An aqueous dispersion comprising a tetrafluoroethylene core-shell polymer and at least one surfactant corresponding to the general formula R.sub.10-[CH.sub.2CH.sub.20].sub.n[R.sub.20].sub.m-R.sub.3 wherein R.sub.1 represents a linear or branched aliphatic hydrocarbon group having at least 8 carbon atoms, preferably 8 to 18 carbon atoms, R2 represents an alkylene having 3 carbon atoms, R3 represents hydrogen, a C1-C3 alkyl group, or a C1-C3 hydroxyalkyl group, n has a value of 0 to 40, m has a value of 0 to 40 and the sum of n+m is at least 2, wherein the dispersion is free of fluorinated emulsifiers or contains them in an amount of less than 50 ppm based on the weight of the dispersion and wherein the core-shell polymer contains an outer shell of tetrafluoroethylene homopolymer. Further provided are methods of making the dispersions, coating compositions comprising the dispersions and article coated by the coating composition.

A method for producing a fluoropolymer which includes polymerizing a fluoromonomer in an aqueous medium in the presence of a fluorine-containing diacyl peroxide represented by the formula (1): XRf.sup.aC(═O)OOC(═O)Rf.sup.bY (wherein X and Y are each independently H or F; and Rf.sup.a and Rf.sup.b are each independently a C1-C6 linear or branched perfluoroalkylene group optionally containing an ether bond) and a fluorine-containing carboxylic acid represented by the following formula (2): Z.sup.2Rf.sup.cCOOH (wherein Z.sup.2 is H or F; and Rf.sup.c is a C1-C3 linear or branched perfluoroalkylene group optionally containing an ether bond when Z.sup.2 is H, and Rf.sup.c is a C1 or C2 linear or branched perfluoroalkylene group optionally containing an ether bond when Z.sup.2 is F) to provide a fluoropolymer.