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    • 6. 发明授权
    • Process for preparing polytetrafluoroethylene fine powder
    • 制备聚四氟乙烯细粉的工艺
    • US4363900A
    • 1982-12-14
    • US268835
    • 1981-06-01
    • Tetsuo ShimizuShun Koizumi
    • Tetsuo ShimizuShun Koizumi
    • C08J3/12C08F2/00C08F2/22C08F2/30C08F2/38C08F2/40C08F14/00C08F14/26C08F114/26C08F114/18
    • C08F114/26Y10T428/2982
    • A process for preparing polytetrafluoroethylene fine powder by polymerization of tetrafluoroethylene in an aqueous medium comprising a water-soluble polymerization initiator and a non-telogenic surfactant capable of keeping colloidal polytetrafluoroethylene particles at a sufficiently stable state, characterized in that the polymerization is carried out at a temperature of 55.degree. to 120.degree. C., and a polymerization retarder chosen from aromatic hydroxy compounds, aromatic amino compounds and quinone compounds which has a water-solubility of not less than 2.5.times.10.sup.-6 mol/liter at 25.degree. C. and does not have any reinitiation ability after its addition or chain transfer to a free radical in the polymerization system is incorporated in the aqueous medium in an amount of 0.7 to 20 ppm at the stage after the initiation of the polymerization and after the consumption of at least 10% by weight of tetrafluoroethylene to be polymerized but before the consumption of 85% by weight of tetrafluoroethylene to be polymerized so that the polymerization time is extended at least 130% in comparison with that of the case wherein the polymerization is effected under the same conditions as above except not using the polymerization retarder, whereby colloidal polytetrafluoroethylene particles, of which the core portions occupying 50% by weight of the total weight of the finally produced particles have a specific gravity of not more than 2.210, of which the specific gravity of the finally produced particles is not more than that of the core portions and of which the average particle size is 0.1 to 0.5 .mu.m, are obtained.
    • 一种通过在含有水溶性聚合引发剂的水性介质中四氟乙烯聚合制备聚四氟乙烯细粉的方法,其能够使胶态聚四氟乙烯颗粒保持在足够稳定的状态,其特征在于聚合反应在 温度为55〜120℃,选自芳香族羟基化合物,芳香族氨基化合物和醌化合物的聚合缓凝剂,其在25℃下的水溶性为2.5×10 -6 mol /升以上, 在聚合体系中添加或链转移到自由基后,在聚合反应开始后的阶段以0.7至20ppm的量掺入水性介质中,并且在消耗至少10 重量%的四氟乙烯待聚合,但在消耗85重量%的四氟乙基之前 烯聚合时间相对于在与上述相同的条件下进行聚合的情况下,聚合时间延长至少130%,除了不使用聚合延迟剂之外,其中胶体聚四氟乙烯颗粒的核心部分 占最终生产的颗粒总重量的50重量%的比重不大于2.210,其中最终生产的颗粒的比重不大于芯部的比重,其平均粒径 为0.1〜0.5μm。