Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Patent
1981-06-04
1983-04-12
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
264323, C08F 1418
Patent
active
043799000
ABSTRACT:
Novel granular, free-flowing, non-melt-fabricable raw polymer powders of tetrafluoroethylene polymers consisting of 0.004 to 0.075 mole % of polymerized units of a perfluoroalkyl vinyl ether and of tetrafluoroethylene units, are described. These powders have an average particle diameter of 450 to 1,400 .mu.m, a bulk density of at least 570 g/l, a powder flow index of .ltoreq.5 seconds/50 g and a grain stability of .ltoreq.5.5 seconds/50 g. They are prepared direct by suspension polymerizing TFE in the presence of the perfluoroalkyl ether, while stirring, the calculated concentration of the ether in the gas phase being kept within the range from 0.1 to 1.0% by volume in the period of time until 1.5% by weight of solid polymer have been formed, and the polymerization being carried out under a total pressure of 5 to 11 bars. A further improvement in bulk density, powder flow and grain stability is achieved if the intensity of stirring is kept at a relatively low level in a critical range, beginning at the formation of 1.5 to 3% by weight of solid polymer and extending to the formation of 8 to 12% by weight of solid polymer. The raw polymer powders which can be obtained in this manner are suitable, as such and without further pretreatment, for the production of ram-extruded articles of all types.
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patent: 4078134 (1978-03-01), Kuhls
patent: 4078135 (1978-03-01), Sulzbach
patent: 4216265 (1980-08-01), Sulzbach
Hoechst Aktiengesellschaft
Michl Paul R.
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