Abstract: To provide a method for producing a PTFE fine powder having a low paste extrusion pressure property by a simple method. The method for producing a PTFE fine power comprises emulsion polymerizing tetrafluoroethylene in the presence of an aqueous medium, a fluorinated surfactant and a radical polymerization initiator, to produce an aqueous PTFE emulsion, and coagulating it in the presence of at least one bulk density-reducing compound selected from the group consisting of ammonia, an ammonium salt and urea in an amount of from 0.4 to 10 parts by mass per 100 parts by mass of PTFE.

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: The present invention provides a method for producing a polytetrafluoroethylene fine powder, which comprises emulsion polymerizing tetrafluoroethylene in the presence of an aqueous medium, a fluorinated surfactant and a radical polymerization initiator to produce an aqueous polytetrafluoroethylene emulsion, mixing and coagulating the aqueous emulsion to separate a polytetrafluoroethylene fine powder, and then drying the polytetrafluoroethylene fine powder in a wet state in an atmosphere containing ammonia.

Abstract: To provide a method for producing a PTFE fine powder having a low paste extrusion pressure property by a simple method. The method for producing a PTFE fine power comprises emulsion polymerizing tetrafluoroethylene in the presence of an aqueous medium, a fluorinated surfactant and a radical polymerization initiator, to produce an aqueous PTFE emulsion, and coagulating it in the presence of at least one bulk density-reducing compound selected from the group consisting of ammonia, an ammonium salt and urea in an amount of from 0.4 to 10 parts by mass per 100 parts by mass of PTFE.

Abstract: To provide a method for producing a PTFE fine powder which can produce a PTFE fine powder having a low paste extrusion pressure property by a simple method. In the presence of an aqueous medium, a fluorinated surfactant and a radical polymerization initiator, tetrafluoroethylene is subjected to emulsion polymerization to produce an aqueous polytetrafluoroethylene and the aqueous medium is mixed and coagulated to separate a polytetrafluoroethylene fine powder, and then the polytetrafluoroethylene fine powder in a wet state is dried in an atmosphere containing ammonia to produce the polytetrafluoroethylene fine powder.

Abstract: To provide an aqueous polytetrafluoroethylene (PTFE) emulsion which does not substantially contain ammonium perfluorooctanoate, and which is obtained by emulsion polymerization. Further, to provide a PTFE fine powder which is obtained from the aqueous PTFE emulsion and is excellent in a paste extrusion processability, and a porous material. An aqueous polytetrafluoroethylene emulsion obtained by carrying out emulsion polymerization of tetrafluoroethylene alone or together with another copolymerizable monomer in an aqueous medium, wherein a fluorinated emulsifier of the formula (1): CF2CF2(O)mCF2CF2OCF2COOA wherein X is a hydrogen atom or a fluorine atom, A is a hydrogen atom, an alkali metal or NH4, and m is an integer of 0 or i, is used in an amount of from 1,500 to 20,000 ppm, based on the final yield of polytetrafluoroethylene.

Abstract: Provided is a process for producing an aqueous fluorinated polymer dispersion having a reduced content of a fluorinated emulsifier by using a weakly basic anion-exchange resin to adsorb and remove a fluorinated emulsifier with excellent efficiency from an aqueous fluorinated polymer dispersion. Also provided is a process for producing an aqueous fluorinated polymer dispersion having a reduced content of a fluorinated emulsifier, wherein the process includes: adding an organic carboxylic acid represented by the following formula (1): Q(CH2)m(CH(OH))nCOOH??(1) wherein Q is H, CH3 or COOH, m and n each independently represent 0 or an integer of from 1 to 4, and 4?n+m?1, to an aqueous fluorinated polymer dispersion containing a fluorinated emulsifier; and then contacting with a weakly basic anion-exchange resin to adsorb and remove the fluorinated emulsifier.

Abstract: To provide a polytetrafluoroethylene (PTFE) aqueous dispersion, which does not substantially contain ammonium perfluorooctanoate and is excellent in mechanical stability, wettability, permeability and coating property, and its product. A PTFE aqueous dispersion comprising from 15 to 70 mass % of PTFE fine particles having an average particle size of from 0.1 to 0.5 ?m, from 1×10?5 to 0.5 mass %, based on the mass of the PTFE, of a fluorinated emulsifier of the formula (1): XCF2CF2(O)mCF2CF2OCF2COOA, wherein X is a hydrogen atom or a fluorine atom, A is a hydrogen atom, an alkali metal or NH4 and m is an integer of 0 or 1, and from 1 to 20 mass %, based on the mass of the PTFE, of a nonionic surfactant.

Abstract: A fluororesin aqueous dispersion comprising from 20 to 70 mass % of microparticles of a fluororesin and from 1 to 12 mass %, based on the mass of the fluororesin, of a non-ionic surfactant represented by the formula (1): R1—O-A-X??(1) wherein R1 is a C6-18 alkyl group, O is an oxygen atom, A is a polyoxyalkylene group comprising from 1 to 3 oxybutylene groups and from 5 to 20 oxyethylene groups, and X is a hydrogen atom or a methyl group.

Abstract: A simple and efficient method for regenerating a basic anion-exchange resin, whereby at the time of removing a fluorinated emulsifier from a basic anion-exchange resin having the fluorinated emulsifier adsorbed thereon, it is unnecessary to provide a safety device/recovery technique necessary for handling an organic solvent by the use of a combustible organic solvent represented by an alcohol, and a burden imposed by e.g. treatment against COD load, is eliminated. A basic anion-exchange resin having a fluorinated emulsifier adsorbed thereon is contacted with an aqueous alkaline solution having a temperature of from 60 to 105° C. to elute the fluorinated emulsifier thereby to regenerate the basic anion-exchange resin.

Abstract: The present invention provides a process for producing an aqueous fluorinated polymer dispersion having a reduced content of a fluorinated emulsifier by using a weakly basic anion-exchange resin to let it adsorb and remove a fluorinated emulsifier with excellent efficiency from an aqueous fluorinated polymer dispersion. A process for producing an aqueous fluorinated polymer dispersion having a reduced content of a fluorinated emulsifier, which comprises adding an organic carboxylic acid represented by the following formula (1) Q(CH2)m(CH(OH))nCOOH??(1) (wherein Q is H, CH3 or COOH, each of m and n which are independent of each other, is 0 or an integer of from 1 to 4, and 4?n+m?1.) to an aqueous fluorinated polymer dispersion containing a fluorinated emulsifier, followed by contact with a weakly basic anion-exchange resin to adsorb and remove the fluorinated emulsifier.

Abstract: To obtain a high concentration aqueous PTFE dispersion containing PTFE at a concentration of from 60 to 75 mass % by dissolving from 0.001 to 0.1 mass %, based on the mass of PTFE, of a specific carboxylic acid salt such as ammonium laurate in a low concentration aqueous dispersion of polytetrafluoroethylene (PTFE) comprising from 1 to 40 mass % of PTFE fine particles, from 0.0001 to 0.02 mass %, based on the mass of PTFE, of a specific fluorine-containing carboxylic acid type emulsifier (for example, ammonium perfluorooctanoate), and from 1 to 20 mass %, based on the mass of PTFE, of a specific nonionic surfactant, and then concentrating the low concentration aqueous dispersion of PTFE.

Abstract: An aqueous dispersion of polytetrafluoroethylene (PTFE) comprising from 55 to 70 mass % of PTFE fine particles having an average particle diameter of from 0.1 to 0.5 ?m, from 0.0001 to 0.02 mass %, based on PTFE, of a specific C8 fluorine-containing carboxylic acid salt (APFO) such as ammonium perfluorooctanoate, from 1 to 20 mass %, based on PTFE, of a specific nonionic surfactant and from 0.01 to 0.3 mass %, based on PTFE, of a specific C5-7 fluorine-containing carboxylic acid salt such as ammonium perfluorohexanoate. The aqueous dispersion of PTFE has excellent properties which can form crack-resistant coatings which do not undergo coloration during baking or form problematic ionic impurities by improving the friction stability of aqueous PTFE dispersions even at APFO concentrations without viscosity increase.

Abstract: To provide a polytetrafluoroethylene (PTFE) aqueous dispersion, which does not substantially contain ammonium perfluorooctanoate and is excellent in mechanical stability, wettability, permeability and coating property, and its product. A PTFE aqueous dispersion comprising from 15 to 70 mass % of PTFE fine particles having an average particle size of from 0.1 to 0.5 ?m, from 1×10?5 to 0.5 mass %, based on the mass of the PTFE, of a fluorinated emulsifier of the formula (1): XCF2CF2(O)mCF2CF2OCF2COOA, wherein X is a hydrogen atom or a fluorine atom, A is a hydrogen atom, an alkali metal or NH4 and m is an integer of 0 or 1, and from 1 to 20 mass %, based on the mass of the PTFE, of a nonionic surfactant.

Abstract: To provide a fluororesin which does not substantially contain perfluorooctanoic acid or its salt, and which has a low residual amount of a fluorinated emulsifier. A fluororesin which is obtained by emulsion-polymerizing a fluorinated monomer in an aqueous medium containing a fluorinated emulsifier of the formula (1): XCF2CF2(O)mCF2CF2OCF2COOA wherein X is a hydrogen atom or a fluorine atom, A is a hydrogen atom, an alkali metal or NH4, and m is an integer of from 0 or 1, and coagulating the obtained aqueous emulsion, followed by drying, wherein the residual amount of the fluorinated emulsifier of the formula (1) is at most 10 ppm.

Abstract: To provide an aqueous polytetrafluoroethylene (PTFE) emulsion which does not substantially contain ammonium perfluorooctanoate, and which is obtained by emulsion polymerization. Further, to provide a PTFE fine powder which is obtained from the aqueous PTFE emulsion and is excellent in a paste extrusion processability, and a porous material. An aqueous polytetrafluoroethylene emulsion obtained by carrying out emulsion polymerization of tetrafluoroethylene alone or together with another copolymerizable monomer in an aqueous medium, wherein a fluorinated emulsifier of the formula (1): XCF2CF2(O)mCF2CF2OCF2COOA wherein X is a hydrogen atom or a fluorine atom, A is a hydrogen atom, an alkali metal or NH4, and m is an integer of 0 or 1, is used in an amount of from 1,500 to 20,000 ppm, based on the final yield of polytetrafluoroethylene.

Abstract: A simple and efficient method for regenerating a basic anion-exchange resin, whereby at the time of removing a fluorinated emulsifier from a basic anion-exchange resin having the fluorinated emulsifier adsorbed thereon, it is unnecessary to provide a safety device/recovery technique necessary for handling an organic solvent by the use of a combustible organic solvent represented by an alcohol, and a burden imposed by e.g. treatment against COD load, is eliminated. A basic anion-exchange resin having a fluorinated emulsifier adsorbed thereon is contacted with an aqueous alkaline solution having a temperature of from 60 to 105° C. to elute the fluorinated emulsifier thereby to regenerate the basic anion-exchange resin.

Abstract: [OBJECT]Providing a polytetrafluoroethylene (PTFE) aqueous dispersion, whereby polytetrafluoroethylene (PTFE) coating film wherein cissing is prevented, the thickening temperature is high, the defoaming property is good, shear stability is good and there is no coloration after the baking, can be obtained. [MEANS OF SOLVING PROBLEMS]A PTFE aqueous dispersion comprising from 20 to 70 mass % of microparticles of a PTFE and from 1 to 12 mass %, based on the mass of the PTFE, of a non-ionic surfactant represented by the formula (1): R1—O-A-X ??(1) wherein R1 is a C6-18 alkyl group, O is an oxygen atom, A is a polyoxyalkylene group comprising from 1 to 3 oxybutylene groups and from 5 to 20 oxyethylene groups, and X is a hydrogen atom or a methyl group.

Abstract: A process for producing an aqueous dispersion of purified polytetrafluoroethylene (PTFE), comprising passing a crude aqueous dispersion of PTFE comprising from 10 to 50 mass % of PTFE fine particles having an average particle diameter of from 0.1 to 0.5 ?m, from 0.05 to 1.0 mass %, based on PTFE, of a fluorine-containing carboxylic acid salt (APFO) and from 2 to 20 mass %, based on PTFE, of a nonionic surfactant through a column packed with a weak basic AER upward at a linear velocity of 0.1 to 2 mm/sec with a contact time of 0.2 to 4 hours to reduce the APFO concentration. The process can increase the absorption of APFO by the anion exchange resin, prevents agglomeration of PTFE during passage and makes it easy to elute the absorbed APFO.

Abstract: A process for producing an aqueous dispersion of purified polytetrafluoroethylene (PTFE), comprising passing a crude aqueous dispersion of PTFE comprising from 10 to 50 mass % of PTFE fine particles having an average particle diameter of from 0.1 to 0.5 ?m, from 0.05 to 1.0 mass %, based on PTFE, of a fluorine-containing carboxylic acid salt (APFO) and from 2 to 20 mass %, based on PTFE, of a nonionic surfactant through a column packed with a weak basic AER upward at a linear velocity of 0.1 to 2 mm/sec with a contact time of 0.2 to 4 hours to reduce the APFO concentration. The process can increase the absorption of APFO by the anion exchange resin, prevents agglomeration of PTFE during passage and makes it easy to elute the absorbed APFO.