METHOD OF PREPARING POLYTETRAFLUOROETHYLENE Russian patent published in 2000 - IPC

FIELD: chemistry of polymers. SUBSTANCE: method comprises polymerizing tetrafluoroethylene in reactor polymerizer in liquid-type medium with previous of reaction volume with inert gas at elevated pressure in the presence of oxidizing-reducing system composed of persulfuric acid salt and divalent iron salt. Addition of persulfuric acid salt and divalent iron is carried out successively. Persulfuric acid salt is added prior to or simultaneously with feeding tetraluoroethylene into reactor polymerizer. Divalent iron salt is added during feeding tetrafluoroethylene after treating at least 10% of working pressure in reactor polymerizer during polymerization process. Polymerization process is carried out at 2-14 atm gauge. 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 calculated for ammonium persulfate at rate of divalent iron salt from 0.00016 g to 0.0067 g per 1 kg of tetrafluoroethylene and at rate of 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 improved quality and, hence, competitiveness of the resulting polytetrafluoroethane and make production more technological due to stabilized polymerization process, thus stabilizing molecular weight and increasing the yield of the desired product which is 95-58%. EFFECT: more efficient preparation method. 24 cl, 2 ex