Abstract: A method for producing an aqueous dispersion of a fluorine-containing elastomer, which includes polymerizing a fluorine-containing monomer in the presence of an aqueous medium and a fluorine-containing compound (A), wherein the fluorine-containing elastomer contains a methylene group in a main chain, the fluorine-containing compound (A) is a compound represented by general formula (A): CXiXk?CXjRa—(CZ1Z2)k—Y3??(A) wherein Xi, Xj, and Xk are the same or different and are F, Cl, H, or CF3; Y3 is a hydrophilic group; Ra is a linking group; Z1 and Z2 are the same or different and are H, F, or CF3; and k is 0 or 1; provided that at least one of Xi, Xk, Xj, Ra, Z1, and Z2 includes F; and the number of carbon atoms in a portion excluding the hydrophilic group is 6 or less, and the fluorine-containing compound (A) is fed after polymerization is initiated.

Abstract: A method for producing a fluoropolymer which method includes polymerizing a perfluoromonomer in an aqueous medium in the presence of a polymer (1) to obtain a fluoropolymer, wherein the content of a polymerized unit derived from the perfluoromonomer in the fluoropolymer is 90 mol % or more based on all polymerized units of the fluoropolymer, the polymer (1) is a polymer of a monomer (1) represented by the general formula (1): CF2?CF—O—R-(Rf-SO3M)m, a polymerized unit (1) derived from the monomer (1) in the polymer (1) is 50% by mass or more based on all polymerized units of the polymer (1), and the content of a dimer and a trimer of the monomer (1) in the polymer (1) is 1.0% by mass or less based on the polymer (1).

Abstract: Provided is a method for producing an aqueous dispersion of a fluorine-containing elastomer, comprising polymerizing a fluorine-containing monomer in the presence of a polymer (1) containing a polymerization unit (1) based on a monomer (1) represented by general formula (1) and an aqueous medium, CF2?CF—R—CZ1Z2—COOM??(1) wherein R is a linking group, Z1 and Z2 are each independently F or CF3, and M is H, a metal atom, NR74, imidazolium optionally having a substituent, pyridinium optionally having a substituent, or phosphonium optionally having a substituent, wherein R7 is H or an organic group.

Abstract: The present disclosure provides a method for producing a perfluoroelastomer aqueous dispersion by polymerizing a perfluoromonomer in the presence of a polymer (1) and an aqueous medium to produce an aqueous dispersion of a perfluoroelastomer, the polymer (1) containing a polymerization unit (1) based on a monomer (1) represented by a general formula (1) and the polymer (1) having an ion exchange capacity of 1.50 meq/g or more.

Abstract: A method for producing an aqueous dispersion of a fluorine-containing elastomer, including polymerizing a fluorine-containing monomer in the presence of a compound (1) having an aromatic ring, a hydrophilic group, and an unsaturated double bond, and an aqueous medium, to produce an aqueous dispersion of a fluorine-containing elastomer containing -CH2- in a main chain.

Abstract: Provided is a method for producing an aqueous dispersion of a fluorine-containing elastomer, comprising polymerizing a fluorine-containing monomer in the presence of a fluorine-containing compound (1) represented by general formula (1) and an aqueous medium to produce an aqueous dispersion of a fluorine-containing elastomer: CX1X2?CX3—Z??General formula (1): wherein X1 to X3 are each independently H, F, or a fluorine-containing alkyl group; when X1 and X2 are both H, X3 is F or a fluorine-containing alkyl group; Z is a group represented by —COOM, —SO3M, —OSO3M, —PO(OM)2, —OPO(OM)2, —BO(OM)2, or —OBO(OM)2; M is H, a metal atom, NR14, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium; and R1 is independently H or an organic group, and any two R1 are optionally bonded to each other to form a ring.

Abstract: A method for producing an aqueous dispersion of a fluorine-containing elastomer, which includes polymerizing a fluorine-containing monomer in the presence of a fluorine-free compound (1) represented by general formula (1): CR1X1?CX2—R2—COOM and an aqueous medium, to produce an aqueous dispersion of the fluorine-containing elastomer containing —CH2— in a main chain. Also disclosed is an aqueous dispersion of the fluorine-containing elastomer and a composition containing the fluorine-containing elastomer.

Abstract: Provided is a method for producing an aqueous dispersion of a fluorine-containing elastomer, comprising polymerizing a fluorine-containing monomer in the presence of a compound (1) having a triple bond and a hydrophilic group and an aqueous medium to produce an aqueous dispersion of a fluorine-containing elastomer.

Abstract: Provided is a method for producing a fluorine-containing polymer, comprising polymerizing a fluorine-containing monomer in the presence of a fluorine-free compound (1) represented by general formula (1), a polymerization initiator, and an aqueous medium to produce the fluorine-containing polymer: CX1X2?CX3—R—Z??General formula (1): wherein X1, X2, and X3 are each independently H or an alkyl group; R is a single bond or an alkylene group; the total number of carbon atoms of X1, X2, X3, and R is 0 to 5; Z is —SO3M, —OSO3M, —P(?O)(OM)2, —OP(O)(OM)2, or —B(OM)2; M is H, a metal atom, NR14, optionally substituted imidazolium, optionally substituted pyridinium, or optionally substituted phosphonium; and R1 is independently H or an organic group, and any two R1 may be bonded to each other to form a ring.

Abstract: A method for producing a fluorine-containing elastomer, which includes carrying out an emulsion polymerization of a fluorine-containing monomer in an aqueous medium in the presence of (A) a fluorine-containing compound containing a functional group capable of reaction by radical polymerization and a hydrophilic group and (B) a hydrocarbon surfactant to provide a fluorine-containing elastomer.

Abstract: A composition including a fluorine-containing polymer and a cross-linking agent, wherein the fluorine-containing polymer contains a vinylidene fluoride unit, a unit of a fluorine-containing monomer (1) represented by the following general formula (1): CHX1?CX2Rf ??(1) wherein one of X1 and X2 is H, the other is F, and Rf is a linear or branched fluoroalkyl group having 1 to 12 carbon atoms, and a unit of a monomer providing a crosslinking site. The monomer providing a crosslinking site is a monomer having at least one crosslinkable group selected from a cyano group, a carboxyl group, an alkoxycarbonyl group and a hydroxyl group. Also disclosed is a crosslinked rubber molded article obtained by crosslinking the composition.