METHOD OF PREPARING POLYTETRAFLUOROETHYLENE Russian patent published in 2001 - IPC

FIELD: organochemical technologies more particularly preparation of fluoroplastics based on fluorocarbon stock. SUBSTANCE: method comprises successively carrying out pyrolysis of difluorochloromethane in the presence of steam and adding octafluorocyclobutane and tetrafluorochloroethane, hardening the pyrolysis products, separating hydrogen chloride, neutralization, compression and condensation of pyrolysate to recover tetrafluoroethylene, polymerization of tetrafluroethylene in polymerization reactor in liquid medium and preliminary deoxidization of reaction volume with inert gas at higher pressure in the presence of redox system composed of persulfuric acid salt and ferrous salt. Addition of persulfuric acid salt and ferrous salt is carried out in succession, persulfuric acid salt being added prior to or simultaneously with addition of tetrafluoroethylene into polymerization reactor, and ferrous salt, when feeding tetrafluoroethylene after building up at least 10% of operating pressure of 2-14 atm gauge in polymerization reactor. The desired product is then separated from mother liquor, medium ranges from 0.05 to 99.0 mg/l, and content of persulfuric acid salt, ranges from 1 to 15 mg/l at consumption rate of ferrous salt from 0.00016 to 0.26532 g per 1 kg of tetrafluroethylene and consumption rate of persulfuric acid salt from 0.0032 to 0.04 g per 1 kg of tetrafluoroethylene, greater efficiency due to better quality and, hence, competitiveness of the resulting polytetrafluoroethylene and better production due to stabilization of polymerization process. This stabilizers molecular weight and increases yield of the desired product. Yield is 75- 98%. EFFECT: more efficient preparation method. 22 cl