| 摘要 |
1,253,598. Aqueous tetrafluoroethylene polymer dispersions. FARBW'ERKE HOECHST A.G. 1 Aug., 1969 [7 Aug., 1968], No. 38710/69. Heading C3P. An aqueous polymer dispersion having a solids content of from 15 to 40% by weight based on the dispersion, wherein the particles have a core consisting of a copolymer of from 90 to 99% by weight of tetrafluoroethylene, based on the copolymer, and at least one comonomer of the formula R 1 R 2 C = CR 3 R 4 , in which at least one of the radicals R 1 , R 2 and R 3 represents a chlorine, bromine, iodine or hydrogen atom and each of the remaining radicals, which may be the same or different, represents a halogen atom or a perhalogenoalkyl or a perhalogenoalkoxy group having from 1 to 10 carbon atoms, two of the groups possibly being linked by a perhalogenated carbon bridge having from 1 to 10 carbon atoms, and an outer shell consisting of polytetrafluoroethylene, which particles have an average diameter in the range of from 0-2 to 0-5 microns, and an average core diameter of from 0-01 to 0-2 microns and wherein the copolymer of the core has a transition point of the crystalline phase in the range of from 290‹ to 322‹ C. may be prepared by (a) copolymerizing in aqueous or non-aqueous dispersion in the presence of an initiator and an emulsifier the tetrafluoroethylene and comonomer to. give a dispersion having a solids content of from 5 to 15% by weight, based on this dispersion; and (b) homopolymerizing tetrafluoroethylene in aqueous dispersion in the presence of some or all of the copolymer dispersion obtained in step (a) and of an initiator and an emulsifier. In the examples tetrafluoroethylene is copolymerized with CF 2 = CFCI, CF 2 = CFBr, CF 2 = CFI, CF 2 = CFH, CFCI = CFCI, CF 2 Cl-CF=CF 2 , CF 3 -CCl=CCl-CF 3 and CCl 2 = CCl 2 in the presence of water, perfluoroammonium octanate, sodium bisulphite, hydrocarbon oil and ammonium persulphate and then tetrafluoroethylene homopolymerized in the presence of these seed dispersions and the same polymerization ingredients. The dispersions may be coagulated by rapid stirring. |
