Daikin Industries, Ltd.

Yoshiyuki Hiraga

Satoshi Komatsu

Tomohisa Noda

Masayuki Namimatsu

Hiroyuki Imanishi

Tadahiro Yabu

Yoshiyuki Takase

Kenji Otoi

Hideki Nakaya

Mitsuo Tsukamoto

Yuji Imahori

Katsuhide Otani

Yoshiki Maruya

Yasuhiro Utsumi

Mai Taguchi

Hideya Saitou

The present invention provides a polymerization inhibitor preventing the self-polymerization of TFE and the generation of a modified polymer of a polymerization inhibitor in a distillation step, particularly in a rectification step, of TFE. The present invention provides a method of distilling tetrafluoroethylene in the presence of a polymerization inhibitor comprising a cyclohexadiene compound of the formula:R-A-Rwherein Ris a hydrocarbon group having 1 to 5 carbon atoms, Ris a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and A is a cyclohexadiene ring. The cyclohexadiene compound is preferably &#x3b1;-terpinene or &#x3b3;-terpinene.

Polymerization inhibitor for tetrafluoroethylene

The present invention provides a fluororesin composition, which is excellent in moldability and crack resistance, a process for preparing the composition and a cable evenly coated with the composition. Specifically, the present invention provides a fluororesin composition wherein polytetrafluoroethylene is compounded to a terpolymer comprising tetrafluoroethylene, hexafluoropropylene and perfluoroalkyl vinylether. Also, the present invention provides a process for preparing the composition which comprises kneading with a multi-screw kneader. Furthermore, the present invention provides a cable which is coated with the resin.

Fluororesin composition, process for preparing the same and cable coated with the same

The present invention provides a fluororesin composition, which is excellent in moldability and crack resistance and particularly, does not cause cone break when coating an electric wire, a process for preparing the composition and a cable coated with the composition. Specifically, the present invention provides a fluororesin composition comprising a tetrafluoroethylene/hexafluoropropylene copolymer and polytetrafluoroethylene compounded thereto, which has a melt flow rate of at least 15 at 372&#xb0; C. Also, the present invention provides a process for preparing the composition which comprises kneading with a multi-screw kneader. Furthermore, the present invention provides a cable which is coated with the resin.

A method of purifying a treatment target substance containing a fluorine-containing surfactant which includes removing at least part of the fluorine-containing surfactant from the treatment target substance by contacting the treatment target substance with a gas containing carbon dioxide. The fluorine-containing surfactant is an ether oxygen-free anionic compound represented by one of general formulae (1) and (2) as defined herein.

Method for purifying material to be treated and method for producing coagulated material

The present invention has for its object to provide a method of producing fluoropolymers with high productivity under comparatively low temperature and low pressure conditions which are conducive to reduced cost of commercial-scale production equipment. The present invention is directed to a method of producing a fluoropolymer which comprises polymerizing a radical polymerizable monomer in a defined reaction-field, said radical polymerizable monomer comprising a fluorine-containing ethylenic monomer and said defined reaction-field being in supercriticality-expression state with a monomer density [&#x3c1;]-monomer critical density [&#x3c1;] ratio of [&#x3c1;/&#x3c1;] not less than 1.1.

Process for producing fluoropolymer

To a fluorine-containing polymer, 0.1 to 10% of a compound having an alkali metal or an alkaline earth metal in terms of the number of atoms of the alkali metal or the alkaline earth metal based on the total number of the above terminal groups, 0.1 to 10% of ammonia in terms of the number of ammonia molecules based on the total number of the above terminal groups, or 0.1 to 10% of a compound having an ammonium group in terms of the number of the ammonium groups based on the total number of the above terminal groups is added, and heated at a temperature of at least 200&#xb0; C. in an atmosphere containing moisture. By this process, unstable terminal groups such as terminal carboxylic acid groups and coloration caused by such terminal groups are effectively removed from the fluorine-containing polymer, and furthermore unstable bonds in the backbones can be removed. The obtained fluorine-containing polymer contains 1.0&#xd7;10spins/g or less of unpaired electrons on the carbon atoms in terms of a spin density measured with electron spin resonance at a temperature of 10K.

Stabilized fluorine-containing polymer and method for stabilizing fluorine-containing polymer

After a melt-processable fluorine-containing copolymer is heated and molten, the copolymer is reheatd in a closed apparatus under a non-static condition at a temperature of, for example, 130&#xb0; C. to the melting point of the fluorine-containing polymer, whereby a content of volatile materials in the copolymer is reduced to 30% or less of an initial content of volatile materials. Thereby, the content of volatile materials in the melt-processable fluorine-containing copolymer, which has been once molten, can be effectively decreased without using a large apparatus while avoiding the contamination of the copolymer with foreign particles.

Method for stabilizing fluorocopolymers

A melt-processable fluorine-containing polymer is melt kneaded with a kneader which has a residence time of at least 10 minutes, a usable volume ratio (usable space in a container/space in a container) of larger than 0.3, and a power factor K of less than 8000, the power factor K being represented by the formula: K&equals;Pv/&mgr;/n in which Pv is a power requirement per unit volume (W/m ), &mgr; is a melt viscosity (Pa.s), and n is a rotation speed (rps), to effectively remove terminal groups and bonds in the backbones, which are unstable during melt kneading, from the melt-processable fluorine-containing polymer, and obtain a colorless fluorine-containing polymer.

Method for stabilizing fluorine-containing polymer

To a fluorine-containing polymer, 0.1 to 10% of a compound comprising an alkali metal or an alkaline earth metal in terms of the number of atoms of the alkali metal or the alkaline earth metal based on the total number of the above terminal groups, 0.1 to 10% of ammonia in terms of the number of ammonia molecules based on the total number of the above terminal groups, or 0.1 to 10% of a compound having an ammonium group in terms of the number of the ammonium groups based on the total number of the above terminal groups is added, and heated at a temperature of at least 2000C in an atmosphere containing moisture. By this process, unstable terminal groups such as terminal carboxylic acid groups and coloration caused by such terminal groups are effectively removed from the fluorine-containing polymer, and furthermore unstable bonds in the backbones can be removed. The obtained fluorine-containing polymer contains 1.0&times;10 spins/g or less of unpaired electrons on the carbon atoms in terms of a spin density measured with spin resonance at a temperature of 10K.

Stabilized fluorine-containing polymer and method for stabilizing fluorine containing polymer

Method of stabilizing fluorine-containing polymer

Coagulated particles having a low water content are separated and recovered from an emulsified dispersion of fluorine-containing polymer particles. A solid-liquid separation method comprising: a step for adding a coagulant in an emulsified dispersion of fluorine-containing polymer particles to coagulate the fluorine-containing polymer particles with stirring and obtain a slurry of coagulated particles, a step for filtrating the slurry, and a step for pressing the obtained cake. It is preferable to continuously carry out the filtration step and pressing step with a filter press or a belt press. Also a washing step may be provided after the filtration step.

Solid-liquid separation method of fluorine-containing polymer particles

A polymerization process, in which when at least one of fluorine-containing olefin monomers in gaseous phase or supercritical phase or a monomer mixture of the fluorine-containing olefin monomer and other monomer copolymerizable therewith is subjected to batch polymerization in an aqueous medium while being diffused to the aqueous medium, a diffusing amount of the monomer or monomer mixture to the aqueous medium is not less than 80% of the theoretical consumption of the monomer or monomer mixture when polymerized at the theoretical polymerization rate. According to the present invention, a polymerization rate is determined by the polymerization reaction but not by the diffusion of monomer gas, and thus higher polymerization rate can be achieved.

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Settsu, Japan

Yoshiyuki Hiraga