METHOD OF PREPARING POLYTETRAFLUOROETHYLENE Russian patent published in 2000 - IPC

FIELD: preparation of fluoroplastics based on fluorocarbon stock. SUBSTANCE: method comprises pyrolyzing difluorochloromethane in the presence of steam and octafluorocyclobutane and tetrafluorochloroethane additives, hardening pyrolysis product, separating hydrogen chloride by-product, neutralizing compressing and condensing pyrolyzate to isolate tetrafluoroethylene, polymerizing tetrafluoroethylene in reactor-polymerizer in liquid-type medium with previous oxygen removal of reaction volume with inert gas at elevated temperature in the presence of oxidizing-reducing system composed of persulfuric acid salt and divalent iron salt. Persulfuric acid salt and divalent iron salt are added successively, persulfuric acid salt being added prior to or simultaneously with feeding tetrafluoroethylene into reactor polymerizer, and divalent iron is added during feeding tetrafluoroethylene after creating at least 10% working pressure of 2-14 atm gauge in reactor polymerizer. Amount of divalent iron salt in liquid type medium varies from 0.05 to 2.5 mg/l, and amount of persulfuric acid salt varies from 1 to 15 mg/l at rate of divalent iron salt from 0.00016 g to 0.0067 g per 1 kg of tetrafluoroethylene and at rate persulfuric acid salt from 0.0032 g to 0.04 g per 1 kg of tetrafluoroethylene. Invention makes it possible to increase economy due to improving quality and, hence, competition of the resulting polytetrafluoroethylene and to make production more technological due to stabilization of polymerization process, thus stabilizing molecular weight and increasing the yield of the desired product which is 95- 98%. EFFECT: more efficient preparation method. 23 cl, 2 ex