PROCESS FOR PREPARING AN AQUEOUS DISPERSION OF POLYTETRAFLUOROETHYLENE

摘要

An aqueous PTFE dispersion containing colloidal PTFE particles having a comparatively large average particle size is prepared by polymerizing TFE in an aqueous medium at a temperature of from 10 DEG to 100 DEG C. in the presence of a fluorine-containing dispersant and a water soluble polymerization initiator, in which, after the initiation of the polymerization and before consumption of 30% of TFE to be polymerized, TFE is polymerized at a pressure not higher than 4 Kg/cm2 for a period in which at least 1 g of TFE per liter of the aqueous medium is consumed, and then the rest of TFE is polymerized at a pressure of from 6 to 30 Kg/cm2, which dispersion does not contain any metal ion that reduces interfacial potential of the colloidal particle.