The present invention provides a method for producing a target fluorine-containing olefin with high conversion and selectivity using a process comprising a dehydrofluorination reaction of a hydrofluorocarbon. The method comprises a first reaction step comprising subjecting a hydrofluorocarbon to dehydrofluorination in the presence of a catalyst. The hydrofluorocarbon is a compound represented by Formula (1): R.sup.fCFYCHZ.sub.2, wherein R.sup.f represents a straight or branched C.sub.1-3 perfluoroalkyl group, and Y and Z each independently represent H or F wherein when all Zs are H, Y represents F. The catalyst comprises chromium oxide represented by the chemical formula: CrO.sub.m (1.5<m<3).

A composition includes a fluoroelastomer, a crosslinking initiator, and a crosslinking agent. The crosslinking agent comprises a compound that comprises two or more structures represented by a formula (3), ##STR00001##
wherein R.sup.1, R.sup.2, and R.sup.3 are independently a hydrogen atom, a fluorine atom, an alkyl group, a fluoroalkyl group, or a substituted or unsubstituted aryl group, a plurality of R.sup.1 are identical to or different from each other, a plurality of R.sup.2 are identical to or different from each other, a plurality of R.sup.3 are identical to or different from each other, provided that at least one of R.sup.1, R.sup.2, and R.sup.3 is a hydrogen atom, and at least one of R.sup.1, R.sup.2, and R.sup.3 is a fluorine atom or a fluorine atom-containing group; n are independently an integer from 1 to 5; and each hydrogen on the benzene rings may be substituted.

A composition includes a fluoroelastomer, a crosslinking initiator, and a crosslinking agent. The crosslinking agent comprises a compound that comprises two or more structures represented by a formula (3), ##STR00001##
wherein R.sup.1, R.sup.2, and R.sup.3 are independently a hydrogen atom, a fluorine atom, an alkyl group, a fluoroalkyl group, or a substituted or unsubstituted aryl group, a plurality of R.sup.1 are identical to or different from each other, a plurality of R.sup.2 are identical to or different from each other, a plurality of R.sup.3 are identical to or different from each other, provided that at least one of R.sup.1, R.sup.2, and R.sup.3 is a hydrogen atom, and at least one of R.sup.1, R.sup.2, and R.sup.3 is a fluorine atom or a fluorine atom-containing group; n are independently an integer from 1 to 5; and each hydrogen on the benzene rings may be substituted.

To provide a PTFE aqueous dispersion which is excellent in mechanical stability, while being not susceptible to foaming. A polytetrafluoroethylene aqueous dispersion which is characterized by containing from 15 to 70 mass % of PTFE particles having an average primary particle diameter of from 0.1 to 0.5 m; from 0.1 to 20,000 ppm, to the PTFE particles, of a fluorinated emulsifier selected from a C.sub.4-7 fluorinated carboxylic acid which may have an etheric oxygen atom, and salts of thereof; from 1 to 20 parts by mass, to 100 parts by mass of the PTFE particles, of a nonionic surfactant represented by R.sup.1O-A-H (wherein R.sup.1 is a C.sub.8-18 alkyl group, and A is a polyoxyalkylene chain); from 0.004 to 0.040 parts by mass, to 100 parts by mass of the PTFE particles, of a polyether polysiloxane copolymer, wherein the polyether chain consists solely of a polyoxypropylene group; and water.

The invention pertains to a method of making fluoropolymer dispersions using certain polymeric derivatives including a plurality of ionisable groups selected from the group consisting of SO.sub.3X.sub.a, PO.sub.3X.sub.a and COOX.sub.a, whereas X.sub.a is H, an ammonium group or a monovalent metal, and to fluoropolymer dispersions therefrom.

The invention pertains to a method of making fluoropolymer dispersions using certain polymeric derivatives including a plurality of ionisable groups selected from the group consisting of SO.sub.3X.sub.a, PO.sub.3X.sub.a and COOX.sub.a, whereas X.sub.a is H, an ammonium group or a monovalent metal, and to fluoropolymer dispersions therefrom.

The invention pertains to a method of making fluoropolymer dispersions using certain polymeric derivatives including a plurality of ionisable groups selected from the group consisting of SO.sub.3X.sub.a, PO.sub.3X.sub.a and COOX.sub.a, whereas X.sub.a is H, an ammonium group or a monovalent metal, and to fluoropolymer dispersions therefrom.

The invention pertains to a method of making fluoropolymer dispersions using certain reactive oligomeric dispersing agents, of given molecular weight, comprising I and/or Br, and a plurality of ionisable groups selected from the group consisting of SO.sub.3X.sub.a, PO.sub.3X.sub.a and COOX.sub.a, whereas X.sub.a is H, an ammonium group or a monovalent metal, and to fluoropolymer dispersions therefrom.

The invention pertains to a method of making fluoropolymer dispersions using certain reactive oligomeric dispersing agents, of given molecular weight, comprising I and/or Br, and a plurality of ionisable groups selected from the group consisting of SO.sub.3X.sub.a, PO.sub.3X.sub.a and COOX.sub.a, whereas X.sub.a is H, an ammonium group or a monovalent metal, and to fluoropolymer dispersions therefrom.

The present invention provides a composition comprising 1) an aqueous dispersion of polymer particles having a core-shell morphology wherein the core protuberates from the shell; wherein the core comprises from 5 to 90 weight percent structural units of a fluoroalkylated monomer, and 2) less than 0.09 weight percent structural units of a phosphorus acid monomer; and wherein the shell comprises from 0.1 to 5 weight percent of itaconic acid or a phosphorus acid monomer, based on the weight of the shell. The present invention addresses a need in the art by providing a way of selectively concentrating fluoroalkyl functionality into polymer particles with acorn morphology, thereby providing an improvement in dirt pick-up resistance of the subsequent coating.