Abstract: The present invention provides a low-molecular weight polytetrafluoroethylene powder that, when used as an additive in a coating material, etc., can form a coating with excellent texture and gliding properties, while also improving dispersibility and viscosity; and a production process therefor. The present invention is a process for producing a low-molecular weight polytetrafluoroethylene powder, the process comprising: an emulsion polymerization step of polymerizing at least tetrafluoroethylene in the presence of a polymerization initiator and an aqueous medium to produce emulsified particles thereof; an agglomeration step of agglomerating the emulsified particles to form an agglomerated powder thereof; and a suspension polymerization step of polymerizing at least tetrafluoroethylene in the presence of the agglomerated powder, a polymerization initiator, and an aqueous medium.

Abstract: The present invention provides a fluororubber composition that has excellent heat resistance and excellent mechanical properties at high temperatures. The fluororubber composition comprises a peroxide cross-linkable fluororubber (A); a carbon black (B); a peroxide cross-linking agent (C); and a low-self-polymerizing cross-linking accelerator (D), wherein to 100 parts by mass of the fluororubber (A), the amount of the carbon black (B) is 5 to 50 parts by mass, the amount of the cross-linking agent (C) is 0.01 to 10 parts by mass, and the amount of the cross-linking accelerator (D) is 2.5 parts by mass or smaller.

Abstract: The present invention relates to a coating agent for a solar cell module obtained by dispersing silica fine particles (A) with an average particle diameter of 15 nm or less and low-refractive index resin particles (B) with a refractive index of 1.36 or less in an aqueous medium, in which the solid content is 5% by mass or less, and the mass ratio of the silica fine particles (A) to the low-refractive index resin particles (B) in the solid content (silica fine particles (A)/low-refractive index resin particles (B)) is more than 20/80 and less than 70/30. The coating agent for a solar cell module is capable of forming an anti-reflection film at room temperature with excellent reflectance-reducing effect, abrasion resistance and weather resistance.

Abstract: The present invention provides an aqueous fluororesin dispersion comprising a melt-processable fluororesin which is low in fluorinated surfactant concentration and excellent in dispersion stability even when the concentration of the melt-processable fluororesin is high. The present invention is related to an aqueous fluororesin dispersion comprising a melt-processable fluororesin particle dispersed in an aqueous medium, wherein a concentration of the melt-processable fluororesin is 55 to 75% by mass relative to the aqueous fluororesin dispersion, and a fluorinated surfactant content in the aqueous fluororesin dispersion is not higher than a level corresponding to 100 ppm of the melt-processable fluororesin.

Abstract: The present invention provides a method for producing a fluororubber composition that has excellent heat resistance and excellent mechanical properties at high temperatures. The production method comprises the step of mixing a fluororubber (A) and a carbon black (B) in the presence of an organic amine compound (C1) and/or an acid acceptor (C2) to prepare a mixed product, wherein the mixed product has a highest temperature Tm of 80° C. to 220° C. while being mixed and has a highest temperature of 80° C. to 220° C. upon being discharged.

Abstract: A catalyst composition comprising a cation and an anion of the formula Anq?Qpm+, wherein m, n, p, and q are positive integers, wherein m*p=n*q, wherein Qm+ is an organo onium, and Aq? is an anion, provided that at least one Aq? is selected from the formula (I) wherein each R independently is H, halo, alkyl, aryl, aralkyl, or cycloalkyl, and which also may be halogenated, fluorinated, or perfluorinated, wherein two or more of R and R? groups may together form a ring, wherein each R group independently may contain one or more heteroatom(s), wherein R? can be the same as R, with the proviso that R? cannot be halo, and wherein the catalyst composition is essentially free of hydrocarbon containing alcohol.

Abstract: An antireflective coating composition includes a photopolymerizable acrylate monomer (C1); a particle-type metal fluoride (C2) with a refractive index of 1.40 or less; a photopolymerization initiator (C3); and at least one liquid dispersion-enhancing chelating agent (C4) selected from the group consisting of Mg(CF3COO)2, Na(CF3COO), K(CF3COO), Ca(CF3COO)2, Mg(CF2COCHCOCF3)2 and Na(CF2COCHCOCF3). This composition ensures good mechanical strength, excellent adhesion to a substrate, short curing time by UV curing, prevention of dust attachment, good erasure of stain, good dust removal and good scratch resistance, so it is usefully for making an antireflective coating film of a display.

Abstract: The present invention provides a low-staining room temperature curable coating composition having an excellent low-staining property and recoatability, and comprising (A) a hydroxyl-containing resin, (B) an isocyanate based curing agent, (C) an organosilicate based hydrophilizing agent, (D) a recoatability modifier and (E) an organic solvent, in which the recoatability modifier (D) comprises at least (D1) an amide-containing polymer and (D2) a silane coupling agent.

Abstract: Provided is a filled fluororesin sheet excellent in stress relaxation properties, in particular stress relaxation properties at a high temperature. The filled fluororesin sheet includes a fluororesin and an inorganic filler having a revised Mohs hardness of not less than 8, in a fluororesin:inorganic filler volume ratio of 30-55:70-45 (wherein the total of the two is 100).

Abstract: Disclosed is an antistaining sheet including a base material sheet and an antistaining layer formed on the base material sheet. The antistaining layer includes a photocatalyst and a thermoplastic resin to be decomposed by the photocatalyst, and thus has a self-collapsing property. The antistaining layer is stronger in self-collapsing property in the surface portion thereof than in the interior portion.

Abstract: An aqueous fluoropolymer dispersion comprising an aqueous medium, fluoropolymer particles, and an amine oxide surfactant. Coagulated fluoropolymer resin is produced from the dispersion by adding an acidic reagent in sufficient amount to cause coagulation and separation of the coagulated fluoropolymer resin from the aqueous medium. Another particulate component such as particular polymer, filler, pigment, solid lubricant, etc., may be added to the dispersion and co-coagulated to form a mixture of coagulated fluoropolymer resin and particulate component.

Abstract: Disclosed herein is a water-based erasable ink for use in a writing instrument. The ink comprises platy-like pigment particles, film formers and an aqueous vehicle. Also disclosed are writing instruments using such inks as well as comprising a reservoir containing a water based erasable ink having a non-shear-thinning composition and a porous fiber nib in fluid communication with this reservoir. Related methods of forming an erasable marking are also disclosed.

Abstract: This invention is comprised of the following innovations: various devices/instruments which may be used in the preparation of a compact monolayer [made up of a suitable organic material (or organic compound)] as well as the carbonization of the latter; efficient methods for preparing a compact monolayer which is free from all “other” materials that were used in the various processes involved in the said preparation of the said compact monolayer; various methods for carbonizing a compact monolayer by means of a suitable “heat source” (which allows the application of a sudden searing “heat” extremely quickly) in order to produce a graphene layer, where the said heat source may be a “hot surface” or a suitable “radiation type beam” such as a suitable laser beam, or a suitable maser beam, or a suitable electron beam; and finally, various methods to provide a protective layer for a graphene layer.

Abstract: A peroxide curable perfluoroelastomer comprising: recurring units derived from tetrafluoroethylene (TFE); recurring units derived from perfluoroethylvinylether (EVE), in an amount of between 2 and 17% by moles, with respect to total recurring units derived from TFE, perfluoromethylvinylether (MVE) and EVE; and recurring units derived from perfluoromethylvinylether (MVE), in an amount of between 23 and 35% by moles, with respect to total recurring units derived from TFE, perfluoromethylvinylether (MVE) and EVE. A process for its manufacture and its use for the manufacture of cured articles.

Abstract: The present invention provides an aqueous fluoropolymer dispersion having good mechanical characteristics and storage stability and containing substantially no fluorinated surfactant. The present invention is related to an aqueous fluoropolymer dispersion comprising a dispersed fluoropolymer particle with an average primary particle diameter of 50 to 400 nm, a surface layer of the dispersed fluoropolymer particle being obtained by emulsion polymerization of a monomer composition consisting of 99.999 to 98 mole percent of tetrafluoroethylene and 0.001 to 2 mole percent of a modifier monomer, a fluorinated surfactant content being not higher than 50 ppm, a fluoropolymer content being 20 to 75% by mass, and a nonfluorinated nonionic surfactant content being 2 to 15% by mass relative to 100% by mass of the fluoropolymer.

Abstract: A peroxide curable perfluoroelastomer comprising: recurring units derived from tetrafluoroethylene (TFE); and recurring units derived from perfluoromethylvinylether (MVE); such perfluoroelastomer possessing a Mooney Viscosity (ML2+9) at 121° C. of from 25 to 140 MU, when measured according to ASTM D1646 standard, and comprising such MVE recurring units in an amount of from 26 to 33% by moles with respect to total moles of TFE and MVE. A process for the manufacture of such perfluoroelastomer, and cured articles obtainable therefrom.

Abstract: Described herein is a belt comprising a body made of elastomeric material, embedded in which is a plurality of longitudinal filiform resistant inserts, and a working surface covered with a covering fabric; advantageously the working surface is constituted by a toothing. The covering fabric is treated with a coating treatment. The coating treatment comprises a fluorinated elastomer. Advantageously, the coating treatment moreover comprises an antifriction agent and an elastomer formed by at least one copolymer obtained starting from a diene monomer and a monomer containing nitrile groups, more advantageously modified with a salt of an unsaturated carboxylic acid.

Abstract: The present invention provides a method of coating at least one surface of a substrate comprising the step of applying a coating comprising fibres onto the at least one surface of the substrate, wherein upon application of the coating on the at least one surface of the substrate, the surface exhibits hydrophilicity or greater hydrophilicity compared to an uncoated surface. The present invention also provides a coating for coating at least one surface of a substrate, wherein the coating comprises fibres, and wherein a surface coated with the coating exhibits hydrophilicity or greater hydrophilicity compared to an uncoated surface. The anti-wetting coating may have a high degree of transparency.

Abstract: Highly fluorinated ion-exchange polymers achieve dissolution in aqueous tetrahydrofuran at lower pressures and temperatures than in other solvents, with few or no side products being formed.

Abstract: A composition for aqueous coating material which has a low content of an organic solvent and presents little burden on the environment and which is excellent in storage stability. A composition for aqueous coating material, which comprises a synthetic resin containing a fluorinated copolymer (A) comprising from 40 to 60 mol % of a fluoroolefin unit, from 3 to 50 mol % of an alkyl vinyl ether or alkyl vinyl ester unit, from 4 to 30 mol % of a hydroxyl group-containing vinyl ether unit and 0.

Abstract: The subject invention provides a process for efficiently producing electret coarse powder useful as electrophoretic particles for a large-screen display. The process for producing electret coarse powder comprises irradiating a fluorine-containing resin sheet with an electron beam or a radial ray to convert the fluorine-containing resin sheet into an electret sheet, and pulverizing the electret sheet.

Abstract: Exemplary embodiments provide materials and methods for polymer-based fixing members that have a textured surface with reduced surface energy and increased surface hydrophobicity.

Abstract: A fluoropolymer composition comprising: at least one thermoplastic partially fluorinated fluoropolymer [polymer (F)]; water; less than 15% wt (based on total weight of composition) of a water-soluble solvent mixture [mixture (M)] comprising: at least one alcohol solvent [solvent (A)]; at least one glycol derivative solvent having a boiling point of at least 100° C. [solvent (GD)], wherein the solvent (GD) is a derivative of a compound comprising at least two hydroxyl groups, wherein at least one of the hydroxyl group has been derivatized to yield an ether or an ester bond.

Abstract: Methods for preparing an electrode comprise: providing a mixture of carbon particles and a solvent and shearing the mixture to form a dispersion of the carbon particles in the solvent; adding non-fibrillated POLY(TETRAFLUOROETHYLENE) to the dispersion to provide a resultant mixture and shearing the resultant mixture until at least a portion of the poly(tetrafluoroethylene) has been fibrillated; processing the resultant mixture into a sheet; and attaching the sheet onto a current collector. Methods for preparing sheet for the electrode and composition for the sheet are also provided.

Abstract: The present invention provides a processing additive which can bring about improvements in moldability at Mooney viscosity levels at which the dispersibility in a melt-processable resin is high and which further can work at reduced addition levels. The present invention is a processing additive comprising a fluoropolymer having an acid value of not lower than 0.5 KOH mg/g.

Abstract: It is an object of the present invention to provide a fluororesin film usable as the outermost layer of a back sheet for a solar cell module, which is a dark type fluororesin film having a sufficient electric insulation property and weather resistance, and which is particularly excellent in thermal resistance; and a back sheet for a solar cell module employing such a film. A dark type fluororesin film, which is a fluororesin film to be used for a back sheet of a solar cell module, which contains an ethylene-tetrafluoroethylene copolymer as the main component and contains from 1.0 to 4.5 parts by mass of a carbon black having a pH of from 8 to 10 as measured according to JIS K6221 section 6.4.2 based on 100 parts by mass of the ethylene-tetrafluoroethylene copolymer. Further, a back sheet 1 comprising a laminate including a fluororesin film 11 being the dark type fluororesin film as the outermost layer.

Abstract: The seal member includes a tetrafluoroethylene-propylene copolymer (FEPM) and carbon nanofibers. The seal member has a number of cycles to fracture of 10 or more when subjected to a tension fatigue test at a temperature of 150° C., a maximum tensile stress of 2 N/mm, and a frequency of 1 Hz. The seal member exhibits excellent heat resistance and abrasion resistance.

Abstract: The present invention relates generally to the use of talc as a chemical foaming agent in perfluoropolymers to form foamable and foamed compositions. For example, in one aspect, a foamable composition is disclosed, which comprises (i) one or more base perfluoropolymers comprising at least 50 percent by weight of the composition, and (ii) talc blended with the one or more base perfluoropolymers, where the talc comprises 3 percent to about 15 percent by weight of the composition. Each of the perfluoropolymers is selected from the group consisting of tetrafluoroethylene/perfluoromethylvinyl ether copolymer (MFA), hexafluoropropylene/tetrafluoroethylene copolymer (FEP) and perfluoroalkoxy (PFA) and any blend thereof, where hydrogen-containing fluoropolymers are absent from the composition. The one or more base perfluoropolymers are melt-processable at one or more elevated processing temperatures of at least about 600° F.

Abstract: A non-stick coating application for high heat welding environments comprised of a fluorinated polymer combined with acidified graphite to which a hardening agent, such as alumina, may be added in some embodiments.

Abstract: A method of manufacturing a polymer material which is allowed to manufacture ?-phase PVDF easily and stably in a short time is provided. The method of manufacturing a polymer material includes a step of mixing an ionic liquid and a polymer compound including ?-phase polyvinylidene difluoride to form a mixture, and then heating the mixture.

Abstract: Tensile strength after heat aging of articles molded from melt-fabricable perfluoropolymer is improved by incorporating polytetrafluoroethylene as dispersed submicrometer-size particles into the melt-fabricable perfluoropolymer.

Abstract: An object of the present invention is to provide an aqueous fluoropolymer dispersion inhibited from viscosity rising and excellent in mechanical stability in spite of a low fluorinated surfactant concentration. The invention provides an aqueous fluoropolymer dispersion comprising particles of a fluoropolymer as dispersed in an aqueous medium wherein a fluorinated surfactant (A) having a molecular weight lower than 1000 amounts to not higher than 100 ppm of the mass of the fluoropolymer, the aqueous fluoropolymer dispersion containing an anionic surfactant (B) other than the fluorinated surfactant (A) as well as a water-soluble polymer (C).

Abstract: The present teachings include a coating composition which includes a liquid, fluoropolymer particles, carbon nanotubes, and a dispersant. The dispersant has a thermal degradation temperature below the melting temperature of the fluoropolymer particles.

Abstract: A resin material for a refrigeration circuit comprising a compressor for a refrigerant, a condenser, a depressurizing/expanding means, and an evaporator, the resin material being disposed in the refrigeration circuit at such a position that the resin part comes into direct contact with the refrigerant. The resin material is characterized in that when R1234yf is used as the refrigerant, the resin material has chemical resistance at least to the refrigerant itself or ingredients generated by the decomposition of the refrigerant. This resin material is prevented from undergoing a chemical reaction with the refrigerant R1234yf itself or ingredients generated by the decomposition thereof. Consequently, refrigerant leakage caused by the decomposition of the resin material is prevented. Furthermore, clogging and a decrease in refrigerating performance, which are caused by the circulation of an undesirable compound through the circuit, are prevented.

Abstract: An aqueous fluoropolymer dispersion comprising an aqueous medium, fluoropolymer particles, and an amine oxide surfactant. Coagulated fluoropolymer resin is produced from the dispersion by adding an acidic reagent in sufficient amount to cause coagulation and separation of the coagulated fluoropolymer resin from the aqueous medium. Another particulate component such as particular polymer, filler, pigment, solid lubricant, etc., may be added to the dispersion and co-coagulated to form a mixture of coagulated fluoropolymer resin and particulate component.

Abstract: An aqueous fluoropolymer dispersion comprising an aqueous medium, fluoropolymer particles, and an amine oxide surfactant. Coagulated fluoropolymer resin is produced from the dispersion by adding an acidic reagent in sufficient amount to cause coagulation and separation of the coagulated fluoropolymer resin from the aqueous medium. Another particulate component such as particular polymer, filler, pigment, solid lubricant, etc., may be added to the dispersion and co-coagulated to form a mixture of coagulated fluoropolymer resin and particulate component.

Abstract: Aqueous dispersions on non-melt flowable PTFE and melt-fabricable perfluoropolymer are mixed together, followed by recovery of the resultant mixture of the dispersed particles of each of these polymers, and melt mixing of the resultant mixture of particles to obtain a blend in which the PTFE particles form the disperse phase and the perfluoropolymer forms the continuous phase, the melt mixing producing advantageous melt viscosities and the blend exhibiting advantageous physical properties even at high PTFE contents of about 30 wt %.

Abstract: The invention relates to the field of chemistry and relates to long-term stable oil PTFE dispersions, such as can be used, for example, in transmissions or bearings, and a method for the production thereof. The object of the present invention is therefore to disclose a long-term stable oil PTFE dispersion as well as a simple and cost-effective method for the production thereof. The object is attained with an oil PTFE dispersion comprising PTFE particles and a monoolefinically or polyolefinically unsaturated oil, wherein molecules of the olefinically unsaturated oil are covalently/chemically coupled to PTFE (primary) particle surfaces via radical reactions, and wherein a permanent charge separation between the PTFE particle surfaces and the coupled oil molecules is present and a fine dispersion of the PTFE particles in the oil or oil mixture is present.

Abstract: The present disclosure relates to a resin composition having excellent thermal stability, light reflectivity and color, and, preferably, flame retardancy. The present disclosure also relates to a method for producing a resin composition which comprises mixing 60 to 99.9 parts by weight of polycarbonate resin (component A) with 0.1 to 40 parts by weight of titanium dioxide pigment (component B), wherein component B (i) satisfies 0.05?(b)?(a)?0.6, when weight. reduction at 23 to 100° C. by thermogravimetric analysis (TGA) is (a) wt % and weight reduction at 23 to 300° C. by TGA is (b) wt %, and (ii) satisfies 0.001?(d)/(c)?0.01 and 0.001?(e)/(c)?0.02, when weight percentages derived from Ti, Al and Si elements in X-ray fluorescence analysis are (c) wt %, (d) wt % and (e) wt %, respectively.

Abstract: Provided are fuser members and printing apparatuses including fuser members. The fuser member can include a substrate and a top coat layer including a hyper nanocomposite disposed over the substrate, wherein the hyper nanocomposite can include a plurality of nanoparticles substantially uniformly dispersed in one or more cross-linked hyperbranched polymers selected from the group consisting of polycarbosilane, polycarbosilixane, polycarbosilazene, and polyfluorocarbon.

Abstract: A highly heat-resistant fluororesin, such as tetrafluoroethylene resin or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, is filled with 0.5 to 1 weight % of a non-black insulating pigment that has a heat resistance such that discoloration does not occur when the fluororesin is baked. Green insulating pigment whose main component is a TiO2—CoO—NiO—ZnO system or a ZnO—CoO system, or blue insulating pigment whose main component is a CoO—Al2O3 system or a CoO—Al2O3—Cr2O3 system is used singly or in a combination, as the non-black insulating pigment. A highly arc-resistant insulator is provided that secures an insulating capacity and at the same time that secures an excellent ability to prevent both interior and exterior deterioration of the insulator and that avoids color heterogeneity and localized discoloration.

Abstract: An aqueous coating composition which has a low content of an organic solvent, whereby a burden on an environment is small; in which an increase of the molecular weight, gelation, etc. are suppressed; which performs excellent storage stability and provides a coating film having good water permeability/water which composition is obtained by dispersing a fluorocopolymer (A) obtained by solution polymerization in an aqueous medium, and which comprises a repeating unit (1) of fluoroolefin, a repeating unit (2) of a vinyl or allyl monomer, a repeating unit (3) of a vinyl or allyl monomer having a hydroxyl group bonded thereto, and a unit (4) of a vinyl or allyl monomer having a carboxylate group bonded thereto, and which comprises a fluorocopolymer (A) wherein a proportion of the repeating unit (4) is from 0.4 mol % to less than 4 mol % based on the total repeating units, and an aqueous medium, wherein an amount of an organic solvent contained in the composition is from 0 to 1 mass %.

Abstract: A composition for forming a gasket comprises a curable elastomer material and 0.1-20 weight % (e.g., 4-10 weight %) carbon nanotubes dispersed throughout the elastomer material. A dispensed bead of elastomer material exhibits a Slump ratio of at least 0.7. The composition provides the correct balance of rheology/dispensing characteristics, seal characteristics, and contamination profile characteristics required in form-in-place gasket applications, while simultaneously providing a conductive form-in-place gasket.

Abstract: A protective coating applied to the underwater portion of a marine vessel operable to inhibit the growth of marine foulants. The coating comprises a polymer, a marine biocide, a preservative, and optionally an antimicrobial agent. In certain embodiments, the marine biocide, preservative, and optional antimicrobial agent are chemically bonded with the polymer thereby significantly reducing the ability of the biocide, preservative, and antimicrobial agent to leach from the coating into the surrounding environment.

Abstract: Disclosed is a diamond film that can solve a problem of a conventional thin film of diamond which, due to insoluble, infusible and hardly machinable properties of the diamond, is produced by plasma CVD requiring the use of a disadvantageously large apparatus. Specifically, a nanodiamond film, which can be simply produced without the need to use a large apparatus, is disclosed. The nanodiamond film is characterized by comprising a nanodiamond. The nanodiamond film has a thickness of not more than 5000 nm.

Abstract: A non-stick coating application for high heat welding environments comprised of a fluorinated polymer combined with acidified graphite to which a hardening agent, such as alumina, may be added in some embodiments.

Abstract: The invention pertains to a multi-phase thermoplastic fluoropolymer composition, comprising a thermoplastic fluoropolymer and discrete domains of melt-processable perfluoropolymer, to the articles therefrom and to a process for manufacturing thermoplastic fluoropolymer compositions. The multi-phase thermoplastic fluoropolymer composition comprises: —at least one thermoplastic fluoropolymer (A); and —from 0.1 to 10% by weight of (A) of at least one melt-processible perfluoropolymer (B), and is characterized in that the polymer (B) is present in the composition in phase-separated domains in a continuous phase mainly comprising (A), at least 75% by volume of said domains having maximal dimension not exceeding 1 ?m. The process of the invention comprises mixing: (i) a thermoplastic fluoropolymer (A); (ii) a melt-processible perfluoropolymer (B) under the form of particles having an average primary particle size not exceeding 300 nm; (iii) and optionally other additives or filling materials.

Abstract: To provide a method for producing a melt-processable fluororesin, which is capable of increasing the molecular weight of the fluororesin and preventing coloration of the fluororesin, by using a specific fluorinated emulsifier other than ammonium perfluorooctanoate. A method for producing a melt-processable fluororesin which is characterized in that a fluorinated monomer is emulsion-polymerized in an aqueous medium containing a fluorinated emulsifier of a formula (I) 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.

Abstract: The present invention describes polymer compositions comprising fluoroelastomer and expanded perlite and uses thereof.

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.