The invention pertains to a method for making a fluoropolymer comprising an aqueous emulsion polymerization of one or more fluorinated monomers wherein said aqueous emulsion polymerization is carried out in the presence of at least one cyclic fluorocompound of the following formula (I): ##STR00001##
wherein X.sub.1, X.sub.2, X.sub.3, equal or different from each other are independently selected among H, F, and C.sub.1-6 (per)fluoroalkyl groups, optionally comprising one or more catenary or non-catenary oxygen atoms; L represents a bond or a divalent group; R.sub.F is a divalent fluorinated C.sub.1-3 bridging group; Y is a hydrophilic function selected among anionic functionalities, cationic functionalities and non-ionic functionalities.

The present invention relates to methods of producing polymerized 2,3,3,3-tetrafluoropropene (poly-1234yf) using one or a combination of the techniques provided herein. In certain embodiments, such techniques include (1) emulsion polymerization; (2) suspension polymerization; (3) solution polymerization; (4) supercritical carbon dioxide polymerization; (5) transition metal catalyzed polymerization; (6) radiation or thermal polymerization; and combinations thereof. A wide array of initiators, catalysts, and solvents may be used in such polymerization processes and may include, but are not limited to, (1) radical initiators; (2) ionic initiators; and (3) single-site and multiple-site catalysts.

The present invention relates to methods of producing polymerized 2,3,3,3-tetrafluoropropene (poly-1234yf) using one or a combination of the techniques provided herein. In certain embodiments, such techniques include (1) emulsion polymerization; (2) suspension polymerization; (3) solution polymerization; (4) supercritical carbon dioxide polymerization; (5) transition metal catalyzed polymerization; (6) radiation or thermal polymerization; and combinations thereof. A wide array of initiators, catalysts, and solvents may be used in such polymerization processes and may include, but are not limited to, (1) radical initiators; (2) ionic initiators; and (3) single-site and multiple-site catalysts.

A composition comprising a mixture of fluoropolyether acids or salts having a number average value of about 800 to about 2500 g/mol. The amount of fluoropolyether acids or salt in the mixture having a molecular weight of not more than 500 g/mol is not more than 50 ppm by weight of the total amount of fluoropolyether acids or salts in the mixture. The amount of fluoropolyether acids or salts in the mixture having a molecular weight of 2500 g/mol or greater is not more than 40% by weight of the total amount of fluoropolyether acids or salts in the mixture. Preferably the fluoropolyether acids or salts comprise an anionic group selected from the group consisting of carboxylate, sulfonate, sulfonamide anion and phosphonate. Also disclosed is an aqueous dispersion polymerization process for fluoropolymer manufacture employing polymerization agent comprising the specified mixture of fluoropolyether acids or salts.

A composition comprising a mixture of fluoropolyether acids or salts having a number average value of about 800 to about 2500 g/mol. The amount of fluoropolyether acids or salt in the mixture having a molecular weight of not more than 500 g/mol is not more than 50 ppm by weight of the total amount of fluoropolyether acids or salts in the mixture. The amount of fluoropolyether acids or salts in the mixture having a molecular weight of 2500 g/mol or greater is not more than 40% by weight of the total amount of fluoropolyether acids or salts in the mixture. Preferably the fluoropolyether acids or salts comprise an anionic group selected from the group consisting of carboxylate, sulfonate, sulfonamide anion and phosphonate. Also disclosed is an aqueous dispersion polymerization process for fluoropolymer manufacture employing polymerization agent comprising the specified mixture of fluoropolyether acids or salts.

A composition comprising a mixture of fluoropolyether acids or salts having a number average value of about 800 to about 2500 g/mol. The amount of fluoropolyether acids or salt in the mixture having a molecular weight of not more than 500 g/mol is not more than 50 ppm by weight of the total amount of fluoropolyether acids or salts in the mixture. The amount of fluoropolyether acids or salts in the mixture having a molecular weight of 2500 g/mol or greater is not more than 40% by weight of the total amount of fluoropolyether acids or salts in the mixture. Preferably the fluoropolyether acids or salts comprise an anionic group selected from the group consisting of carboxylate, sulfonate, sulfonamide anion and phosphonate. Also disclosed is an aqueous dispersion polymerization process for fluoropolymer manufacture employing polymerization agent comprising the specified mixture of fluoropolyether acids or salts.

A crosslinking agent includes a compound represented by the following formula (1).

##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, m is an integer from 2 to 6, l is an integer from 0 to 2, and each hydrogen on the benzene ring(s) may be substituted.

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.

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.

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.