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    Polytetrafluoroethylene fine powder and process for producing the same
    3.
    发明授权
    Polytetrafluoroethylene fine powder and process for producing the same 失效
    聚四氟乙烯细粉及其制造方法

    公开(公告)号：US4159370A

    公开(公告)日：1979-06-26

    申请号：US850539

    申请日：1977-11-11

    申请人： Shun Koizumi ,  Shigeru Ichiba ,  Tetsuo Simizu ,  Chuzo Okuno ,  Tosinori Kadowaki ,  Katsutoshi Yamamoto

    发明人： Shun Koizumi ,  Shigeru Ichiba ,  Tetsuo Simizu ,  Chuzo Okuno ,  Tosinori Kadowaki ,  Katsutoshi Yamamoto

    IPC分类号： C08F14/00 ,  C08F2/00 ,  C08F2/16 ,  C08F2/18 ,  C08F14/26 ,  C08F214/26 ,  C08J3/12 ,  C08F114/26

    CPC分类号： C08F14/26

    摘要： Polytetrafluoroethylene fine powders which have an average molecular weight of not less than 5,000,000, preferably not less than 5,500,000, an amorphous index of not more than 0.1, preferably not more than 0.09, a number average primary particle size of 0.1 to 0.4 micron, preferably 0.15 to 0.38 micron, and a sharp endothermic peak at a temperature between 343.degree. C. and 350.degree. C. on the melting diagram by a differential scanning calorimeter, said sharp peak having an endothermic ratio of not more than 0.3, preferably not more than 0.27, and a half value width of the endothermic peak of not more than 8 degrees, preferably not more than 6 degrees, and a process for producing the polytetrafluoroethylene fine powders. The polytetrafluoroethylene fine powders have an excellent stretchability and are useful for electric wire coating, small diameter tubes, large diameter tubes, sealing tapes and the like.

    摘要翻译： 平均分子量不小于5,000,000，优选不小于5,500,000的聚四氟乙烯细粉末，数均一次粒径为0.1〜0.4微米，优选为0.15以下的无定形指数为0.1以下，优选为0.09以下 通过差示扫描量热计在熔点上在343℃和350℃之间的温度下具有尖锐的吸热峰，所述尖峰的吸热比不大于0.3，优选不大于0.27 ，吸热峰的半值宽度为8度以下，优选为6度以下，以及聚四氟乙烯细粉的制造方法。 聚四氟乙烯细粉末具有优异的拉伸性，可用于电线涂布，小直径管，大直径管，密封带等。

    Process for preparing polytetrafluoroethylene fine powders
    4.
    发明授权
    Process for preparing polytetrafluoroethylene fine powders 失效
    制备聚四氟乙烯精细粉末的方法

    公开(公告)号：US4098975A

    公开(公告)日：1978-07-04

    申请号：US776919

    申请日：1977-03-11

    申请人： Tetsuo Shimizu ,  Shigeru Ichiba ,  Shun Koizumi ,  Chuzo Okuno

    发明人： Tetsuo Shimizu ,  Shigeru Ichiba ,  Shun Koizumi ,  Chuzo Okuno

    IPC分类号： C08F2/00 ,  C08F2/16 ,  C08F2/18 ,  C08F14/00 ,  C08F14/26

    CPC分类号： C08F14/26

    摘要： A process for preparing a polytetrafluoroethylene fine powder by polymerizing tetrafluoroethylene in an aqueous medium containing a polymerization initiator and a dispersant, coagulating the resulting polymer, washing the coagulated polymer when desired, and drying the polymer, characterized in that after at least 30 wt. % of the whole amount of the tetrafluoroethylene to be polymerized has been polymerized at a constant temperature, the polymerization is conducted at an altered temperature at which the same whole amount, when polymerized, gives a polymer having an amorphous index at least 0.01 higher than when the whole amount is polymerized at the first-mentioned temperature.