Abstract: A tetrafluoroethylene(TFE)/perfluoro (alkyl vinyl ether) (PVE) copolymer and a method for producing the copolymer, wherein the molar ratio of polymerized units based on TFE/polymerized units based on PVE is in the range of from 98.1/1.9 to 95.0/5.0, and its melt flow rate at 372° C. is from 35 to 60 g/10 min., and a weight-average molecular weight/a number-average molecular weight is from 1 to 1.7. The copolymer of TFE/PVE is excellent in the mechanical properties and the injection molding properties.

Abstract: A method for producing a tetrafluoroethylene/perfluoro (alkyl vinyl ether) type copolymer (PFA), which comprises carrying out the polymerization in a polymerization medium (such as CHFClCF2CF2Cl) in the presence of a chain transfer agent of a C1 or 2 hydrofluorocarbon (such as CH3CF2H) by means of a polymerization initiator (such as (FCF2CF2CF2COO)2). PFA obtained by this method has a small amount of unstable terminal groups contained in its molecule and is excellent in thermal stability and cracking resistance against a liquid reagent. Further, the amount of elution of fluorine ions is little even when it is applied to a component of e.g. an equipment for the production of semiconductors.

Abstract: An agricultural covering material made of a fluorine-containing polymer film having a dynamic viscoelastic modulus of from 1 to 70 kg/mm2, a tensile strength of from 1.5 to 5.0 kg/mm2, a specific gravity of from 1.0 to 2.0 and a contact angle with water of at most 106°.

Abstract: A fluorine-containing copolymer containing polymer units (A) based on tetrafluoroethylene or chlorotrifluoroethylene, polymer units (B) based on ethylene, polymer units (C) based on vinyl acetate and polymer units (D) based on a compound represented by the general formula CH2═CX(CF2)nY wherein each of X and Y which are independent of each other, is a hydrogen atom or a fluorine atom, and n is an integer of from 2 to 10, wherein (A)/(B) is from 20/80 to 80/20 in a molar ratio, (C)/((A)+(B)) is from 1/1,000 to 15/100 in a molar ratio, (D)/((A)+(B)) is from 1/1,000 to 15/100 in a molar ratio, and the volumetric rate of flow is from 1 to 1,000 mm3/sec.

Abstract: A method for producing a tetrafluoroethylene/perfluoro (alkyl vinyl ether) type copolymer (PFA), which comprises carrying out the polymerization in a polymerization medium (such as CHFClCF2CF2Cl) in the presence of a chain transfer agent of a C1 or 2 hydrofluorocarbon (such as CH3CF2H) by means of a polymerization initiator (such as (FCF2CF2CF2COO)2). PFA obtained by this method has a small amount of unstable terminal groups contained in its molecule and is excellent in thermal stability and cracking resistance against a liquid reagent. Further, the amount of elution of fluorine ions is little even when it is applied to a component of e.g. an equipment for the production of semiconductors.

Abstract: A method for producing a fluorine-containing polymer having polymer units based on a fluoroolefin as the main constituting units, wherein a hydrofluoroalkyl ether is used as a polymerization medium.

Abstract: A polytetrafluoroethylene powder having an average particle size of at most 200 &mgr;m is stirred and granulated in a 2 phase liquid medium comprising water and perfluoroalkyl alkyl ether, to obtain a granulated powder of polytetrafluoroethylene.

Abstract: A fluorine-containing copolymer comprising:(a) from 0.05 to 20 mol % of polymer units based on at least one fluorinated comonomer selected from the group consisting of fluorinated comonomers of the following formulae (1), (2) and (3):X--R.sup.f --CY.dbd.CH.sub.2 (1)X--R.sup.f --O--CF.dbd.CF.sub.2 (2)CF.sub.3 --(CF.sub.2).sub.n --(O--CF(CF.sub.3)--CF.sub.2).sub.m --O--CF.dbd.CF.sub.2 (3)wherein Y is a fluorine atom or a hydrogen atom, R.sup.f is a C.sub.2-12 bivalent fluorinated organic group, X is a fluorine atom, a chlorine atom or a hydrogen atom, n is an integer of from 0 to 3, and m is an integer of from 1 to 4,(b) from 30 to 85 mol % of polymer units based on tetrafluoroethylene,(c) from 1 to 30 mol % of polymer units based on propylene, and(d) from 5 to 68.5 mol % of polymer units based on vinylidene fluoride.

Abstract: A method for producing a fluorine-containing copolymer, which comprises suspension-polymerizing at least one fluoroolefin, or at least one fluoroolefin and at least one monomer copolymerizable with the fluoroolefin, in a polymerization medium comprising at least one solvent selected from the group consisting of a perfluorocarbon, a hydrofluorocarbon and a hetero atom-containing perfluorocarbon, water and a fluorine-containing surfactant.

Abstract: A method for producing a fluorinated polymer containing fluoroolefin units as the main constituting units, wherein CF.sub.3 (CF.sub.2).sub.n CH.sub.2 CH.sub.3 or CF.sub.3 (CF.sub.2).sub.n H, wherein n is an integer of from 1 to 8), the is used as the polymerization medium, and CF.sub.2 ClCF.sub.2 CHClF and/or CF.sub.3 CF.sub.2 CHCl.sub.2 as a chain transfer agent.Using the polymerization medium which is less likely to bring about an environmental destruction, it is possible to obtain a fluorinated polymer excellent in the heat resistance, solvent resistance, chemical resistance, etc. Further, the above chain transfer agent has good compatibility with the polymerization medium which scarcely brings about the environmental destruction, whereby it is possible to efficiently produce a fluorinated polymer excellent in the heat resistance and solvent resistance.

Abstract: A flame-retardant resin having excellent moldability composed essentially of a fluorine-containing copolymer obtained by the copolymerization of tetrafluoroethylene, chlorotrifluoroethylene and ethylene, wherein the copolymer comprises from 10 to 60 molar % of tetrafluoroethylene, from 20 to 60 molar % of chlorotrifluoroethylene and from 20 to 40 molar % of ethylene, and has a thermal decomposition temperature of at least 325.degree. C.