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    FREE-FLOWING SINTERING POWDERS WHICH HAVE IMPROVED PROPERTIES AND ARE BASED ON TETRAFLUOROETHYLENE POLYMERS, AND A PROCESS FOR THEIR MANUFACTURE
    2.
    发明专利
    FREE-FLOWING SINTERING POWDERS WHICH HAVE IMPROVED PROPERTIES AND ARE BASED ON TETRAFLUOROETHYLENE POLYMERS, AND A PROCESS FOR THEIR MANUFACTURE 未知

    公开(公告)号：CA1192348A

    公开(公告)日：1985-08-20

    申请号：CA366609

    申请日：1980-12-11

    Applicant: HOECHST AG

    Inventor： KUHLS JUERGEN ,  HARTWIMMER ROBERT

    IPC: C08J3/12 ,  C08F14/00 ,  C08F14/26 ,  C08F214/26 ,  C08F259/08 ,  C08J3/16 ,  C08L1/00 ,  C08L27/00 ,  C08L27/12 ,  C08L27/18

    Abstract: of the disclosure Free-flowing sintering powders based on polymers containing at least 98.5 % by weight of tetrafluoroethylene units can be prepared from colloidal polymer dispersions obtained in a customary manner by emulsion polymerization, stirring being carried out initially, optionally with the addition of an inorganic salt, until thickening, indicated by optical inhomogeneities, is achieved, an organic liquid which wets the polymer particles and is soluble in water to the extent of not more than 15 % by weight then being added and stirring then being continued until granules are produced. The polymers preferably contain up to 1.5 % by weight of polymerized units of at least one modifying, perfluorinated monomer. The free-flowing sintering powders have a high bulk density, an excellent flow time and further advantageous properties. They can be provided with customary fillers and are suitable for ram extrusion and for press-sinter processing to give sintered blocks and subsequently veneer-cut films.

    COPOLYMERS OF TETRAFLUOROETHYLENE AND PROCESS FOR THEIR MANUFACTURE
    3.
    发明专利
    COPOLYMERS OF TETRAFLUOROETHYLENE AND PROCESS FOR THEIR MANUFACTURE 未知

    公开(公告)号：CA1102491A

    公开(公告)日：1981-06-02

    申请号：CA285724

    申请日：1977-08-30

    Applicant: HOECHST AG

    Inventor： HARTWIMMER ROBERT ,  KUHLS JUERGEN

    IPC: C08F14/00 ,  C08F2/16 ,  C08F14/28 ,  C08F16/00 ,  C08F16/14 ,  C08F214/26

    Abstract: of the disclosure The invention relates to a process for the copolymerization of tetrafluoroetbylene with fluorinated alkylvinyl ethers of the formula XCF2-(CF2)n-O-CF=CF2 wherein X is H, C1 or F, and n is 1 to ?, in the presence of hexafluoropropene, and the thermoplastic terpolymers so obtained. The copolymerization may be carried out according to the suspension process or the emulsion process in liquid phase in the presence of liquid chain transfer agents . In the presence of hexafluoropropene, the amount of fluorinated alkylvinyl ethers incorporated is considerably increased. The terpolymers in accordance with this invention are distinguished by a number of interesting properties.

    CONTINUOUS PROCESS FOR THE AGGLOMERATION OF PTFE POWDERS IN A LIQUID MEDIUM, AND MODIFIED PTFE POWDER OBTAINED THEREBY
    7.
    发明专利
    CONTINUOUS PROCESS FOR THE AGGLOMERATION OF PTFE POWDERS IN A LIQUID MEDIUM, AND MODIFIED PTFE POWDER OBTAINED THEREBY 未知

    公开(公告)号：CA1184728A

    公开(公告)日：1985-04-02

    申请号：CA410946

    申请日：1982-09-08

    Applicant: HOECHST AG

    Inventor： KUHLS JUERGEN ,  WEISS EDUARD ,  BURGSTALLER GOTTFRIED

    IPC: C08J3/16 ,  C08F14/00 ,  C08F16/00 ,  C08F16/14 ,  C08F214/26 ,  C08J3/12

    Abstract: of the disclosure: A process for the continuous agglomeration of granular tetrafluoroethylene polymer powders which cannot be processed from the melt to give molding powders having a high bulk density, an improved powder flow and particle stability and a narrow particle size distribution is described. In this process, the powder to be agglomerated is first introduced uniformly into a pretreatment stage and is dispersed and pre-agglomerated in this stage in the liquid agglomeration medium, composed of water and an organic liquid capable of wetting polytetrafluoroethylene, is then agglomerated to the desired average particle diameter in an agglomeration stage and is finally treated further in an after-treatment stage in order to develop the final shape of the particles. Finally, the powder is separated from the liquid medium and is dried. This makes it possible to obtain, in an economical manner and with excellent processing properties, high-grade agglomerated molding powders of such tetrafluoroethylene polymers, in particular of such polymers which have been modified with small quantities of perfluoro-(alkyl-vinyl) ethers.

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