Abstract: To provide a modified polytetrafluoroethylene excellent in breaking strength. The modified polytetrafluoroethylene comprises a polymer having units based on tetrafluoroethylene and a polymer having units based on a monomer represented by formula (1), wherein the content of the units based on a monomer represented by formula (1) is from 10 to 500 mass ppm, to all units in the modified polytetrafluoroethylene, and the standard specific gravity is from 2.155 to 2.175, CH2?CR1-L-R2??Formula (1): wherein R1 represents a hydrogen atom or an alkyl group, L represents a single bond, —CO—O—*, —O—CO—*, or —O—, * represents a bonding position to R2, and R2 represents a hydrogen atom, an alkyl group, or a nitrile group.

Abstract: To provide a method for producing an aqueous polytetrafluoroethylene dispersion, whereby the formation of fluorinated oligomers as byproducts is minimized, CFT of the formed coating film is large, and a highly concentrated aqueous polytetrafluoroethylene dispersion is easily obtainable.

Abstract: To provide a method for producing modified polytetrafluoroethylene, in which formation of a fluorinated oligomer as a by-product is little. A method for producing modified polytetrafluoroethylene which contains substantially no C6-34 fluorinated oligomer containing hydrophilic functional groups and which contains substantially no fluorinated surfactant, the method comprising conducting copolymerization of tetrafluoroethylene and a monomer having a polar group, in a liquid dispersion 1 comprising a polymer containing units derived from a non-fluorinated monomer and an aqueous medium, or in a solution 2 obtainable by mixing at least one member selected from the group consisting of a polyalkylene oxide compound and a hydrocarbon-containing surfactant, with an oxidizing agent, in an aqueous medium, under such a condition that the amount of the monomer having a polar group to be used, is at most 0.150 mass % to the whole amount of tetrafluoroethylene, to obtain modified polytetrafluoroethylene.

Abstract: To provide a fluorinated elastic copolymer and a fluorinated elastic copolymer composition, whereby it is possible to obtain a crosslinked rubber article which has practically sufficient rubber physical properties and which is, at the same time, excellent in low-temperature characteristics; a crosslinked rubber article; and a method for producing a fluorinated elastic copolymer. The fluorinated elastic copolymer comprises units based on tetrafluoroethylene, units based on CF2?CFORf1 (Rf1 is a C1-10 perfluoroalkyl group), units based on CF2?CF(OCF2CF2)n—(OCF2)m—ORf2 (Rf2 is a C1-4 perfluoroalkyl group, n is an integer of from 0 to 3, m is an integer of from 0 to 4, and n+m is an integer of from 1 to 7), and units based on a fluorinated monomer having at least two polymerizable unsaturated bonds.

Abstract: A method for producing a modified polytetrafluoroethylene, the method including: polymerizing tetrafluoroethylene in an aqueous medium in which a polymer having units based on a fluorine-free monomer is present. The fluorine-free monomer is a monomer represented by formula (1): CH2?CR1-L-R2, where R1 is a hydrogen atom or an alkyl group, L is a single bond, —CO—O—*, —O—CO—* or —O—, * is a bonding position to R2, and R2 is an alkyl group. To the total amount of tetrafluoroethylene supplied to the polymerization, a proportion of the polymer is from 0.001 to 0.050 mass %.

Abstract: A modified polytetrafluoroethylene which can be formed under a low extrusion pressure and with which changes of the extrusion pressure are suppressed, even in paste extrusion at a high RR ratio, and its production method. The modified polytetrafluoroethylene having units based on tetrafluoroethylene, 0.020 to 0.040 mass % of units based on a monomer represented by the following formula (1), and 0.003 to 0.080 mass % of units based on a monomer represented by the following formula (2), each based on all units of the modified polytetrafluoroethylene. The monomers of formulae (1) and (2) are represented by: CH2?CH—CnF2n+1 (1), wherein n is from 2 to 6; and CF2?CFO(LO)mRf (2), wherein L is a perfluoroalkylene group, Rf is a perfluoroalkyl group, and m is an integer of from 0 to 4.

Abstract: To provide a method for producing an aqueous dispersion of polytetrafluoroethylene, whereby formation of fluorinated oligomers as byproducts is little and CFT of a coating film to be formed is large. A method for producing an aqueous dispersion of polytetrafluoroethylene, which comprises step A1 of polymerizing a non-fluorinated monomer in an aqueous medium to obtain a solution 1 containing a polymer comprising units based on said non-fluorinated monomer, step A2 of conducting polymerization of tetrafluoroethylene in said solution 1 without substantially adding a surfactant to said solution 1, to obtain an aqueous emulsion containing polytetrafluoroethylene particles, and step A3 of adding a nonionic surfactant to said aqueous emulsion, and then concentrating said aqueous emulsion to obtain an aqueous dispersion of polytetrafluoroethylene, wherein the amount of said non-fluorinated monomer used is at most 200 mass ppm to the amount of said tetrafluoroethylene supplied to the polymerization system.

Abstract: To provide a fluorinated elastic copolymer excellent in adhesion, processability, mechanical properties, heat resistance and chemical resistance. A fluorinated elastic copolymer having units based on a monomer (a), units based on a monomer (b) and optionally units based on a monomer (c), which has an iodine atom bonded to a terminal of a molecular chain and the unit based on the monomer (b) adjacent to the iodine atom, and which has a proportion of the units based on the monomer (b) of from 0.09 to 2.0 mol % to all units. Monomer (a): monomer selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene, a perfluoro(alkyl vinyl ether) and 2,3,3,3-tetrafluoropropene; monomer (b): a monomer having at least one type of functional group selected from the group consisting of an epoxy group, a hydroxy group, a carbonyl group-containing group and an isocyanate group; monomer (c): a monomer selected from the group consisting of ethylene and propylene.

Abstract: To provide a method for producing crosslinked rubber excellent in hardness and transparency. The method for producing crosslinked rubber of the present invention is a method for producing crosslinked rubber, which comprises crosslinking a fluorinated copolymer in a composition comprising the fluorinated copolymer, a crosslinking agent and a crosslinking co-agent, wherein the fluorinated copolymer is a copolymer having units based on tetrafluoroethylene and units based on a perfluoro(alkyl vinyl ether), the content of the units based on tetrafluoroethylene is from 65 to 90 mol % to all units of the fluorinated copolymer, in the composition, the content of the crosslinking agent is from 0.03 to 0.7 part by mass to 100 parts by mass of the fluorinated copolymer, the content of the crosslinking co-agent is from 0.1 to 2.5 parts by mass to 100 parts by mass of the fluorinated copolymer, and the hardness is from 65 to 100.

Abstract: To provide a fluorinated elastic copolymer having a low content of metal elements and being excellent in crosslinkability. This fluorinated elastic copolymer has iodine atoms and has units a based on tetrafluoroethylene, units b based on a monomer having one polymerizable unsaturated bond (but excluding tetrafluoroethylene), and units c based on a fluorinated monomer having at least two polymerizable unsaturated bonds, wherein the metal content is at least 0.3 ppm by mass and at most 20.0 ppm by mass.

Abstract: To provide a fluorinated copolymer excellent in low temperature properties and crosslinking property as a fluororubber, and a method for producing it. A fluorinated copolymer which has units based on tetrafluoroethylene, units based on propylene and units based on a compound represented by the following formula 1, and which has either one or both of iodine atoms and bromine atoms: CF2?CFO(Rf1O)nRf2??formula 1 wherein Rf1 is a C1-3 perfluoroalkylene group, Rf2 is a C1-6 perfluoroalkyl group, n is an integer of from 1 to 4, and in a case where n is from 2 to 4, a plurality of Rf1 may be the same or different.

Abstract: To provide a method for producing modified polytetrafluoroethylene, in which formation of a fluorinated oligomer as a by-product is little. A method for producing modified polytetrafluoroethylene which contains substantially no C6-34 fluorinated oligomer containing hydrophilic functional groups and which contains substantially no fluorinated surfactant, the method comprising conducting copolymerization of tetrafluoroethylene and a monomer having a polar group, in a liquid dispersion 1 comprising a polymer containing units derived from a non-fluorinated monomer and an aqueous medium, or in a solution 2 obtainable by mixing at least one member selected from the group consisting of a polyalkylene oxide compound and a hydrocarbon-containing surfactant, with an oxidizing agent, in an aqueous medium, under such a condition that the amount of the monomer having a polar group to be used, is at most 0.150 mass % to the whole amount of tetrafluoroethylene, to obtain modified polytetrafluoroethylene.

Abstract: To provide a fluorinated elastic copolymer capable of obtaining a crosslinked rubber which is excellent in tensile strength and has a low compression set under high temperature conditions; a method for producing such a fluorinated elastic copolymer; a crosslinked rubber; and a method for producing such a crosslinked rubber. A fluorinated elastic copolymer having structural units based, respectively, on monomers (a), (b) and (c), and further having iodine atoms. Monomer (a): at least one member selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene and perfluoro(alkyl vinyl ether). Monomer (b): at least one member selected from the group consisting of compounds represented by formula (I): CR1R2?CR3—R4—CR5?CR6R7 (I) (wherein R1, R2, R3, R5, R6 and R7 are each independently a hydrogen atom, a fluorine atom or a methyl group; and R4 is a C1-10 perfluoroalkylene group which may have an etheric oxygen atom inserted between carbon atoms).

Abstract: To provide a fluorinated elastic copolymer excellent in adhesion, processability, mechanical properties, heat resistance and chemical resistance. A fluorinated elastic copolymer having units based on a monomer (a), units based on a monomer (b) and optionally units based on a monomer (c), which has an iodine atom bonded to a terminal of a molecular chain and the unit based on the monomer (b) adjacent to the iodine atom, and which has a proportion of the units based on the monomer (b) of from 0.09 to 2.0 mol % to all units. Monomer (a): monomer selected from the group consisting of tetrafluoroethylene, hexafluoropropylene, vinylidene fluoride, chlorotrifluoroethylene, a perfluoro(alkyl vinyl ether) and 2,3,3,3-tetrafluoropropene; monomer (b): a monomer having at least one type of functional group selected from the group consisting of an epoxy group, a hydroxy group, a carbonyl group-containing group and an isocyanate group; monomer (c): a monomer selected from the group consisting of ethylene and propylene.

Abstract: To provide a modified PTFE excellent in heat resistance. The modified polytetrafluoroethylene comprises a polymer having units based on tetrafluoroethylene and a polymer having units based on a fluorine-free monomer, wherein the endothermic amount ratio R calculated by a prescribed method is at least 0.65.

Abstract: To provide a modified polytetrafluoroethylene excellent in breaking strength. The modified polytetrafluoroethylene comprises a polymer having units based on tetrafluoroethylene and a polymer having units based on a monomer represented by formula (1), wherein the content of the units based on a monomer represented by formula (1) is from 10 to 500 mass ppm, to all units in the modified polytetrafluoroethylene, and the standard specific gravity is from 2.155 to 2.175, CH2?CR1-L-R2??Formula (1) wherein R1 represents a hydrogen atom or an alkyl group, L represents a single bond, —CO—O—*, —O—CO—*, or —O—, * represents a bonding position to R2, and R2 represents a hydrogen atom, an alkyl group, or a nitrile group.

Abstract: To provide a novel method for producing a modified PTFE. The method for producing a modified polytetrafluoroethylene comprises polymerizing tetrafluoroethylene in an aqueous medium in which a polymer comprising units based on a fluorine-free monomer is present.

Abstract: To provide a fluorinated elastic copolymer composition whereby it is possible to obtain a crosslinked rubber article which is excellent in low temperature characteristics and which has sufficient hardness; and a crosslinked rubber article which is excellent in low temperature characteristics and which has sufficient hardness. The fluorinated elastic copolymer composition comprises a fluorinated elastic copolymer having units based on tetrafluoroethylene and units based on CF2?CFORf1 (wherein Rf1 is a C1-10 perfluoroalkyl group), and an organic silicon compound which has a perfluoropolyether chain and at least two polymerizable unsaturated bonds.

Abstract: To provide a fluorinated elastic copolymer and a fluorinated elastic copolymer composition, whereby it is possible to obtain a crosslinked rubber article which has practically sufficient rubber physical properties and which is, at the same time, excellent in low-temperature characteristics; a crosslinked rubber article; and a method for producing a fluorinated elastic copolymer. The fluorinated elastic copolymer comprises units based on tetrafluoroethylene, units based on CF2?CFORf1 (Rf1 is a C1-10 perfluoroalkyl group), units based on CF2?CF(OCF2CF2)n—(OCF2)m?OR f2 (Rf2 is a C1-4 perfluoroalkyl group, n is an integer of from 0 to 3, m is an integer of from 0 to 4, and n+m is an integer of from 1 to 7), and units based on a fluorinated monomer having at least two polymerizable unsaturated bonds.

Abstract: To provide a fluorinated elastic copolymer in which the contents of metal elements and chloride ions are low, and a method for producing a fluorinated elastic copolymer, whereby it is possible to obtain a fluorinated elastic copolymer in which the contents of metal elements and chloride ions are low. A fluorinated elastic copolymer in which the content of metal elements is at most 20.0 ppm by mass and the content of chloride ions is at most 1 ppm by mass; and a method for producing a fluorinated elastic copolymer, which comprises coagulating a fluorinated elastic copolymer in a latex containing the fluorinated elastic copolymer by using an acid containing no metal elements or no chloride ions, and washing the coagulated fluorinated elastic copolymer with a liquid medium having a content of metal elements of at most 2.0 ppm by mass and a content of chloride ions of at most 2 ppm by mass.