Daikin Industries, Ltd.

Yoshiki Maruya

Katsuhide Otani

Mitsuru Kishine

Yutaka Ueta

Satoshi Komatsu

Masanori Kitaichi

Yoshiyuki Hiraga

Hideya Saito

Kiyohiko Ihara

Sadashige Irie

Hiroshi Aihara

Mitsuo Tsukamoto

Kazuhiro Nakai

A process for preparing a fluorine-containing polymer through emulsion polymerization method which enhances productivity while maintaining excellent physical properties of the fluorine-containing polymer and comprises (a) a first polymerization step for emulsion-polymerizing a fluorine-containing monomer or a mixture of a fluorine-containing monomer and a non-fluorine-containing monomer in an aqueous medium in the presence of a radical polymerization initiator and an emulsifying agent, (b) a dilution step for diluting the obtained aqueous emulsion of polymer particles with water to reduce the number of emulsified polymer particles per unit amount of aqueous medium in the emulsion and a concentration of emulsifying agent, and (c) a second polymerization step for emulsion-polymerizing a fluorine-containing monomer and/or a non-fluorine-containing monomer in the obtained diluted emulsified solution.

Process for preparing fluorine-containing polymer

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.

Process for the polymerizing of flourine-containing olefin monomer

Process for preparing low molecular weight polytetrafluoroethylene

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Settsu, Japan

Yoshiki Maruya