To provide a membrane/electrode assembly excellent in the power generation characteristics even under low or no humidity conditions or under high humidity conditions, and an electrolyte material suitable for a catalyst layer of the 5 membrane/electrode assembly, an electrolyte material is used which comprises a polymer (H) having a unit (A) which has an ion exchange group and in which all hydrogen atoms (excluding H.sup.+ of the ion exchange group) bonded to carbon atoms are substituted by fluorine atoms, a unit (B) which has a 5-membered ring and in which all hydrogen atoms bonded to carbon 10 atoms are substituted by fluorine atoms, and a unit (C) which has neither an ion exchange group nor a ring structure, has an ether bond, and has an ether equivalent of at most 350 as established by the following formula (I) and in which all hydrogen atoms bonded to carbon atoms are substituted by fluorine atoms:
Ether equivalent=the molecular weight of the monomer forming the unit (C)/the 15 number of ether bonds in the monomer forming the unit (C)(I).

To provide a fluorinated elastomer from which it is possible to produce a crosslinked article excellent in cold resistance and excellent in mechanical strength; a fluorinated elastomer composition containing said elastomer; and a fluorinated elastomer crosslinked article obtained by molding and crosslinking said composition. The fluorinated elastomer comprises units (A) based on vinylidene fluoride and units (B) based on a perfluorovinyl ether represented by CF.sub.2CFOR.sup.f, and has iodine atoms at main chain terminals, wherein the molar ratio [(A)/(B)] of units (A) to units (B) is from 88/12 to 50/50. In the formula, R.sup.f is a C.sub.1-20 perfluoroalkyl group having a branched structure, or a C.sub.2-20 perfluoroalkyl group having a branched structure and also having an etheric oxygen atom between carbon atoms.

Disclosed are copolymers formed by copolymerization of: (1) one or more hydrofluoroolefin monomer(s) selected from the group consisting of hydrofluoroethylenes, hydrofluoropropenes, hydrofluorobutenes, hydrofluoropentenes and combinations of these, and preferably selected from 2,3,3,3-tetrafluoropropene, 1,3,3,3-tetrafluoropropene, with said 1,3,3,3-tetrafluoropropene preferably comprising, consisting essentially of or consisting of trans-1,3,3,3-tetrafluoropropene, and combinations of these, and (2) one or more chlorofluoroethylene monomers, preferably chlorotrifluoroethylene (CTFE) monomers, wherein the mole ratio of monomer (1) to monomer (2) is preferably from about 30:1 to about 1:30.

To provide a binder for a storage battery device whereby favorable adhesion is obtainable and swelling by an electrolytic solution can favorably be suppressed. A binder for a storage battery device, which is made of a fluorinated copolymer comprising structural units (A), structural units (B) and structural units (C), wherein the molar ratio of the structural units (C) to the total of all the structural units excluding the structural units (C) is from 0.01/100 to 3/100: structural units (A): structural units derived from a monomer selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride and chlorotrifluoroethylene; structural units (B): structural units derived from ethylene or propylene; and structural units (C): structural units derived from a C.sub.5-30 organic compound having at least two double bonds and at least one of the double bonds being a double bond of a vinyl ether group or a double bond of a vinyl ester group.

To provide an effective process for producing a fluorinated polymer excellent in adhesion, by using a polymerization medium having a low ozone layer destruction potential.

A process for producing a fluorinated polymer, which comprises polymerizing a monomer mixture comprising a fluorinated monomer and a polar functional group-containing monomer (excluding one having a fluorine atom) in a polymerization medium, wherein the polymerization medium contains a medium compound represented by C.sub.mH.sub.2m+1xF.sub.xOC.sub.nH.sub.2n+1yF.sub.y (wherein m is an integer of from 1 to 6, n is an integer of from 1 to 6, x is from 0 to (2m+1), y is from 0 to 2n, and (x+y) is at least 1), and wherein a solution obtained by dissolving the polar functional group-containing monomer in the polymerization medium is continuously or intermittently added to a polymerization reaction system.

Described herein is a composition comprising a fluorinated polysulfinic acid or a salt thereof having the following formula (I): ##STR00001##
wherein X.sub.1, X.sub.2, and X.sub.3 are independently selected from H, F, Cl, Br, I, CF.sub.3, and CH.sub.3 and wherein at least one of X.sub.1, X.sub.2, or X.sub.3 is H; R.sub.1 is a linking group; Z.sub.1 and Z.sub.2 are independently selected from Br, Cl, I, F, CF.sub.3, and a perfluorinated alkyl group; M is a cation; p is 0 or 1; and n is at least 2. Also described is a method of making the partially fluorinated polysulfinic acid or salt thereof.

Described herein is a composition comprising a fluorinated polysulfinic acid or a salt thereof having the following formula (I): ##STR00001##
wherein X.sub.1, X.sub.2, and X.sub.3 are independently selected from H, F, Cl, Br, I, CF.sub.3, and CH.sub.3 and wherein at least one of X.sub.1, X.sub.2, or X.sub.3 is H; R.sub.1 is a linking group; Z.sub.1 and Z.sub.2 are independently selected from Br, Cl, I, F, CF.sub.3, and a perfluorinated alkyl group; M is a cation; p is 0 or 1; and n is at least 2. Also described is a method of making the partially fluorinated polysulfinic acid or salt thereof.

This invention pertains to a novel perfluoroalkyl-crosslinked fluoropolymer with perfluoroether pendant groups. The perfluoroalkyl-crosslinked fluoropolymer hereof is particularly well-suited for use in chemically and thermally aggressive environments, in part by virtue of the highly stable perfluoroalkyl crosslink. The perfluroalkyl-crosslinked fluoropolymer hereof can be prepared by crosslinking in situ a crosslinkable precursor in the form of a shaped article. A crosslinkable precursor is a fluoropolymer having a dichloroamino-functionalized functionalized perfluoroether pendant group.

The present invention provides a fluorine-containing polymer that is capable of forming a coating film having excellent liquid repellency and liquid slippability. Specifically provided is a fluorine-containing polymer containing a Unit A having a fluorine-containing aliphatic ring structure that constitutes the main chain, and a Unit B based on a fluorine-containing monomer b that has at least one type of hetero atom selected from the group consisting of an oxygen atom and a sulfur atom, and does not have a fluorine-containing aliphatic ring structure constituting the main chain, wherein the residual rate of polymerizable carbon-carbon double bonds is not more than 0.5 mol %.

A copolymer of polytetrafluoroethylene and a perfluoro acid (e.g., Nafion) is neutralized by a base to yield its corresponding salt, and a high-boiling-point compatible solvent is used as a substituting solvent, with the original, low-boiling-point solvent being removed by rotor evaporation. The resulting dispersion is screen printable, and its viscosity is controllable by adjusting its solids content. This screen-printable salt dispersion is especially useful in printed electronics applications such as sensors.