The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 12, 1983
Filed:
Jun. 04, 1981
Reinhard A Sulzbach, Burghausen/Salzach, DE;
Hoechst Aktiengesellschaft, , DE;
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.