The purpose of the present invention is to obtain a fluorine-containing compound which is easily stabilized without irradiation of ultraviolet light, by efficiently converting a CI bond in an iodine-containing compound having a group represented by CFRfI (wherein Rf is a fluorine atom or a perfluoroalkyl group) to a CH bond. A method for producing a fluorine-containing compound having an iodine atom content reduced than the following iodine-containing compound, which comprises subjecting an iodine-containing compound having a group represented by CFRfI (wherein Rf is a fluorine atom or a perfluoroalkyl group) to deiodinating treatment in the presence of an organic peroxide and a hydrogen-containing compound having a group represented by CHR.sup.1CHR.sup.2CHR.sup.3 (wherein R.sup.1, R.sup.2 and R.sup.3 are each independently a hydrogen atom or an alkyl group).

The present invention aims to provide a fluorine-containing polymer powder that is environmentally less harmful and forms a sufficiently smooth film without impairing the properties of the fluorine-containing polymers. The present invention relates to a fluorine-containing polymer powder including a fluorine-containing polymer prepared by suspension polymerization, which contains less than 0.1 ppm of a fluorine-containing surfactant and has an average particle size of not less than 1 m and less than 100 m and a bulk density of 0.90 to 1.50 g/cm.sup.3.

The present invention aims to provide a fluorine-containing polymer powder that is environmentally less harmful and forms a sufficiently smooth film without impairing the properties of the fluorine-containing polymers. The present invention relates to a fluorine-containing polymer powder including a fluorine-containing polymer prepared by suspension polymerization, which contains less than 0.1 ppm of a fluorine-containing surfactant and has an average particle size of not less than 1 m and less than 100 m and a bulk density of 0.90 to 1.50 g/cm.sup.3.

The invention relates to an efficient polymerization process and its use to produce novel copolymers with a specific micro structure. In particular, the invention relates to butyl rubbers with novel micro structure, preferably those obtainable by copolymerization of monomer mixtures comprising isobutylene and isoprene in diluents comprising 2,3,3,3 -tetrafluoro-1-propene. In a further aspect the invention relates to halogenated copolymers obtainable from such novel copolymers by halogenation.

To provide a curable fluorinated polymer excellent in solubility in an alcohol, a method for its production and a cured product of the fluorinated polymer. A fluorinated polymer comprising units represented by the following formula (1), wherein in at least some of the units represented by the formula (1), Z.sup.1 is NR.sup.1NR.sup.2H or NR.sup.3OR.sup.4:

##STR00001##

in the formula (1), X.sup.1 and X.sup.2 are each independently a hydrogen atom or a fluorine atom, Q.sup.1 is a single bond or an etheric oxygen atom, R.sup.f1 is a fluoroalkylene group, or a fluoroalkylene group with at least 2 carbon atoms, having an etheric oxygen atom between carbon-carbon atoms, Z.sup.1 is NR.sup.1NR.sup.2H, NR.sup.3OR.sup.4 or OR.sup.5, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently a hydrogen atom or an alkyl group, and R.sup.5 is an alkyl group.

To provide a curable fluorinated polymer excellent in solubility in an alcohol, a method for its production and a cured product of the fluorinated polymer. A fluorinated polymer comprising units represented by the following formula (1), wherein in at least some of the units represented by the formula (1), Z.sup.1 is NR.sup.1NR.sup.2H or NR.sup.3OR.sup.4:

##STR00001##

in the formula (1), X.sup.1 and X.sup.2 are each independently a hydrogen atom or a fluorine atom, Q.sup.1 is a single bond or an etheric oxygen atom, R.sup.f1 is a fluoroalkylene group, or a fluoroalkylene group with at least 2 carbon atoms, having an etheric oxygen atom between carbon-carbon atoms, Z.sup.1 is NR.sup.1NR.sup.2H, NR.sup.3OR.sup.4 or OR.sup.5, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently a hydrogen atom or an alkyl group, and R.sup.5 is an alkyl group.

A method for recovering a hydrofluorocarbon, including: producing a wet fluoropolymer by suspension polymerization, solution polymerization, or bulk polymerization in the presence of a hydrofluorocarbon; vaporizing and discharging vaporizable substances including the hydrofluorocarbon by heating the wet fluoropolymer in a container; and transferring the discharged vaporizable substances to a cooling means to cool the substances.

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).

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).

To provide a polymerization initiator composition for a fluorinated polymer which will not destroy ozone layer and which has less influence over polymerization of a monomer for a fluorinated polymer, and a method for producing a fluorinated polymer by which a fluorinated polymer having a sufficient molecular weight can be obtained.

An initiator composition for a fluorinated polymer, which comprises an organic peroxide, and a saturated hydrocarbon compound having at least one tertiary or quaternary carbon atom, and a method for producing a fluorinated polymer using the polymerization initiator composition, and a polymerization method comprising a step of recovering a polymerization solvent and a step of separating the saturated hydrocarbon compound from the recovered polymerization solvent.