The present invention is directed to partially fluorinated copolymers and the production thereof. More specifically, the copolymers, which are preferably produced by a solution polymerization process, preferably have at least three units, the first unit selected from 2,3,3,3-tetrafluoropropene and 1,3,3,3-tetrafluoropropene, the second unit having a polymerized monomer selected from the vinyl esters and vinyl ethers, and the third unit having a polymerized monomer derived from a hydroxyl group-containing vinyl ether. The resulting copolymer is environmentally friendly, has favorable molecular weight characteristics, and may be shipped economically in high concentration.

To provide an ion exchange membrane for alkali chloride electrolysis which has high membrane strength and low membrane resistance, thereby capable of reducing the electrolysis voltage during alkali chloride electrolysis. In this ion exchange membrane (1) for alkali chloride electrolysis, a reinforcing material 20 formed by weaving reinforcing yarns 22 and sacrificial yarns 24 is disposed in a layer (S) 14, and layer (S) 14 has elution portions 28 formed by elution of at least portions of the sacrificial yarns 24. In a cross section perpendicular to reinforcing yarns of the warp, the average distance (d1) from the center of a reinforcing yarn 22 to the center of the adjacent reinforcing yarn 22, the total area (P) obtained by adding the cross-sectional area of an elution portion 28 and the cross-sectional area of a sacrificial yarn 24 remaining in the elution portion 28, the number (n) of elution portions between adjacent reinforcing yarns 22, and the ion exchange capacity of a layer (Sa) located on the most anode side in the layer (S) 14 during alkali chloride electrolysis, are controlled to be within specific ranges, respectively.

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.

An acrylic rubber sheet excellent in storage stability and processability, a method for producing the same, an acrylic rubber bale obtained by laminating the sheets, a mixture obtained by mixing the acrylic rubber sheet and the acrylic rubber bale, a method for producing the mixture and a rubber cross-linking product obtained by cross-linking the mixture. The acrylic rubber sheet comprises, an acrylic rubber mainly composed of a (meth) acrylic acid ester and having a weight average molecular weight (Mw) of 100,000 to 5,000,000 and a ratio (Mz/Mw) of a Z-average molecular weight (Mz) and a weight average molecular weight (Mw) is 1.3 or more, and the acrylic rubber sheet contains a phenolic anti-aging agent, and a gel amount is 50 wt % or less. The acrylic rubber sheet is extremely excellent in storage stability and processability and the sheet can be easily produced by the claimed method.

An acrylic rubber sheet excellent in storage stability and processability, a method for producing the same, an acrylic rubber bale obtained by laminating the sheets, a mixture obtained by mixing the acrylic rubber sheet and the acrylic rubber bale, a method for producing the mixture and a rubber cross-linking product obtained by cross-linking the mixture. The acrylic rubber sheet comprises, an acrylic rubber mainly composed of a (meth) acrylic acid ester and having a weight average molecular weight (Mw) of 100,000 to 5,000,000 and a ratio (Mz/Mw) of a Z-average molecular weight (Mz) and a weight average molecular weight (Mw) is 1.3 or more, and the acrylic rubber sheet contains a phenolic anti-aging agent, and a gel amount is 50 wt % or less. The acrylic rubber sheet is extremely excellent in storage stability and processability and the sheet can be easily produced by the claimed method.

A fluorine-containing elastomer including a vinylidene fluoride unit and an unsaturated ether unit selected from a unit based on a monomer (1) represented by the general formula (1): CH.sub.2═CFCF.sub.2—O—Rf.sup.1 and a unit based on a monomer (2) represented by the general formula (2): CH.sub.2═CF—O—Rf.sup.2, and having a glass transition temperature of 20° C. or lower, a crosslinkable composition including the fluorine-containing elastomer, and a molded article obtained from the fluorine-containing elastomer or the crosslinkable composition.

A fluorine-containing elastomer including a vinylidene fluoride unit and an unsaturated ether unit selected from a unit based on a monomer (1) represented by the general formula (1): CH.sub.2═CFCF.sub.2—O—Rf.sup.1 and a unit based on a monomer (2) represented by the general formula (2): CH.sub.2═CF—O—Rf.sup.2, and having a glass transition temperature of 20° C. or lower, a crosslinkable composition including the fluorine-containing elastomer, and a molded article obtained from the fluorine-containing elastomer or the crosslinkable composition.

To provide a sulfonic acid group-containing polymer which is capable of forming a low hydrogen permeable membrane, which shows a high ion exchange capacity, and which shows a proper softening temperature. The sulfonic acid group-containing polymer has units u1 represented by the following formula u1, units u2 represented by the following formula u2, and units u3 based on tetrafluoroethylene,

##STR00001##

in the formula u1, R.sup.F1 and R.sup.F2 are each independently a C.sub.1-3 perfluoroalkylene group, and Z.sup.+ is a hydrogen ion, a metal ion, or an ammonium ion,

—[CF.sub.2—CF(CF.sub.2O—R.sup.f1)]—  Formula u2

in the formula u2, R.sup.f1 is a perfluoroalkyl group which may contain a SO.sub.3.sup.−Z.sup.+ group and/or an etheric oxygen atom.

To provide a sulfonic acid group-containing polymer which is capable of forming a low hydrogen permeable membrane, which shows a high ion exchange capacity, and which shows a proper softening temperature. The sulfonic acid group-containing polymer has units u1 represented by the following formula u1, units u2 represented by the following formula u2, and units u3 based on tetrafluoroethylene,

##STR00001##

in the formula u1, R.sup.F1 and R.sup.F2 are each independently a C.sub.1-3 perfluoroalkylene group, and Z.sup.+ is a hydrogen ion, a metal ion, or an ammonium ion,

—[CF.sub.2—CF(CF.sub.2O—R.sup.f1)]—  Formula u2

in the formula u2, R.sup.f1 is a perfluoroalkyl group which may contain a SO.sub.3.sup.−Z.sup.+ group and/or an etheric oxygen atom.

Disclosed are copolymers formed by copolymerization of: (1) one or more hydrofluoroolefin monomer(s) such as hydrofluoropropenes, (2) one or more of an alkyl vinyl ether monomer(s) that are not substituted with a reactive group, and (3) one or more reactive group substituted, lower alkyl vinyl ether monomer(s) wherein the copolymer has a MWn of from about 1000 to about 6000 grams/mole and other advantageous properties.