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: 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 method for producing a fluorinated polymer which does not require an emulsifier as an essential component while an aqueous medium with little environmental burden is used.

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 production method for an aqueous emulsion of modified polytetrafluoroethylene which is environmentally friendly and which is suitable for producing a stretched porous body having excellent breaking strength. A production method for an aqueous emulsion of modified polytetrafluoroethylene, which is a method to obtain an aqueous emulsion of modified polytetrafluoroethylene particles having an average primary particle diameter of from 0.10 to 0.30 ?m, by subjecting tetrafluoroethylene and a perfluoroalkyl ethylene to emulsion polymerization in an aqueous medium, using a polymerization initiator, in the presence of a fluorinated anionic surfactant having a LogPOW of from 2.4 to 3.

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 modified PTFE 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. A modified polytetrafluoroethylene having units based on tetrafluoroethylene, units based on a monomer represented by the following formula (1) and units based on a monomer represented by the following formula (2), wherein the content of the units based on the monomer represented by the formula (1) is from 0.020 to 0.040 mass % to all units of the modified polytetrafluoroethylene, and the content of the units based on the monomer represented by the formula (2) is from 0.003 to 0.080 mass % to all units of the modified polytetrafluoroethylene: CH2?CH—CnF2n+1??(1) wherein n is from 2 to 6; 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 polytetrafluoroethylene aqueous dispersion which is excellent in mechanical stability, while being not susceptible to foaming. The polytetrafluoroethylene aqueous dispersion comprises: 15 to 70 mass % of polytetrafluoroethylene particles having an average primary particle size of 0.1 to 0.5 ?m; 0.1 to 20,000 ppm, to the mass of the polytetrafluoroethylene particles, of a fluorinated emulsifier selected from C4-7 fluorinated carboxylic acids which may have an ether oxygen atom, and salts thereof; 1 to 20 parts by mass, per 100 parts by mass of the PTFE particles, of a nonionic surfactant represented by R1—O-A-H (wherein R1 is a C8-18 alkyl group, and A is a polyoxyalkylene chain); 0.01 to 3.0 parts by mass, per 100 parts by mass of the polytetrafluoroethylene particles, of a compound represented by the formula (2) (wherein R is a C2-4 alkyl group, n is 1 or 2, and each of m1 and m2 is an average repeating number of oxyethylene groups, with (m1+m2) being 1 to 6); and water.

Abstract: To provide a method for producing a tetrafluoroethylene copolymer-containing aqueous dispersion excellent in stability against a mechanical stress.

Abstract: To provide a production method for an aqueous emulsion of modified polytetrafluoroethylene which is environmentally friendly and which is suitable for producing a stretched porous body having excellent breaking strength. A production method for an aqueous emulsion of modified polytetrafluoroethylene, which is a method to obtain an aqueous emulsion of modified polytetrafluoroethylene particles having an average primary particle diameter of from 0.10 to 0.30 ?m, by subjecting tetrafluoroethylene and a perfluoroalkyl ethylene to emulsion polymerization in an aqueous medium, using a polymerization initiator, in the presence of a fluorinated anionic surfactant having a LogPOW of from 2.4 to 3.

Abstract: To provide a process for producing a PTFE molding powder having a high bulk density from granular polymer particles without using an emulsifying agent having problems of bioaccumulation and toxicity. A process for producing a polytetrafluoroethylene molding powder, which comprises a step of suspension-polymerizing a monomer containing at least 99.8 mass % of tetrafluoroethylene in an aqueous medium to produce granular polymer particles and a step of milling the granular polymer particles, wherein the aqueous medium contains a compound represented by RF(OCF(X1)CF2)k-1OCF(X2)COO?M+, at a concentration of from 0.5 to 2,000 ppm. RF is a perfluorinated C1-10 monovalent organic group, X1 and X2 are fluorine atoms, etc., and M+ is an ammonium ion or the like.

Abstract: To produce a PTFE aqueous emulsion, whereby the environmental load is little, the stability of the aqueous emulsion is high, and a molded product having high heat resistance can be obtained. A process for producing a PTFE aqueous emulsion, which comprises emulsion-polymerizing tetrafluoroethylene (TFE) by means of at least one fluorinated emulsifier selected from the group consisting of a C4-8 fluorinated carboxylic acid having from 1 to 4 etheric oxygen atoms in its main chain, and its salts, to obtain an aqueous emulsion containing polytetrafluoroethylene (PTFE) microparticles having an average primary particle size of from 0.1 to 0.3 ?m, wherein at the beginning of the emulsion polymerization of TFE, a (polyfluoroalkyl)ethylene (a) represented by “CH2?CH—Rf1”, and/or a comonomer (b) having a monomer reactivity ratio rTFE of from 0.1 to 8 in copolymerization with tetrafluoroethylene, is incorporated to the emulsion polymerization system, so as to be from 0.001 to 0.

Abstract: To provide a process for producing a PTFE molding powder having a high bulk density from granular polymer particles without using an emulsifying agent having problems of bioaccumulation and toxicity. A process for producing a polytetrafluoroethylene molding powder, which comprises a step of suspension-polymerizing a monomer containing at least 99.8 mass % of tetrafluoroethylene in an aqueous medium to produce granular polymer particles and a step of milling the granular polymer particles, wherein the aqueous medium contains a compound represented by RF(OCF(X1)CF2)k-1OCF(X2)COO?M+, at a concentration of from 0.5 to 2,000 ppm. RF is a perfluorinated C1-10 monovalent organic group, X1 and X2 are fluorine atoms, etc., and M+ is an ammonium ion or the like.

Abstract: To provide a process for producing a PTFE fine powder having a high bulk density, whereby the concentration of non-coagulated PTFE in coagulation wastewater is low. Tetrafluoroethylene is emulsion-polymerized in the presence of an aqueous medium, at least one fluorinated emulsifier selected from the group consisting of a C4-7 fluorinated carboxylic acid having from 1 to 4 etheric oxygen atoms in its main chain, and its salts, and a radical polymerization initiator, to produce a polytetrafluoroethylene emulsion; the obtained polytetrafluoroethylene emulsion is adjusted to a polytetrafluoroethylene concentration of from 10 to 25 mass %, followed by coagulation and stirring at a coagulation temperature of from 5 to 18° C. to separate a wet-state polytetrafluoroethylene fine powder; and the obtained wet-state polytetrafluoroethylene fine powder is dried to produce a polytetrafluoroethylene fine powder.