Patent ID: 7705113

Claim:
A process for preparing peroxidic perfluoropolyethers of formula (I) A-CF 2 O(CF 2 CF 2 O) m (CF 2 O) n —(CF 2 CF 2 OO) m1 (CF 2 OO) n1 CF 2 —B (I) wherein A, B, equal to or different from each other are selected from the group consisting of —Cl, —F, —F 2 CCl, —COF, —OCOF, —OF 3 ; m, m1, n, n1 are integers such that the (m+m1)/(n+n1) ratio is between 0.6 and 1.3, where (n+n1) is different from 0 and the m/n ratio is between 0.5 and 1.2, where n is different from 0; having a peroxidic content (PO) lower than or equal to 1.2 and a number average molecular weight in the range of 35,000-45,000, wherein: when m/n is between 0.5 and 0.8 (n being different from 0); the PO is between 0.5 and 1.0; when m/n is above 0.8 and less than or equal to 1.2 (n being different from 0), the PO is above 1.0 and less than or equal to 1.2; the process comprising tetrafluoroethylene (TFE) photooxidation in the presence of UV light and oxygen, at a temperature of from −80° C. to −40° C. in the presence of a mixture of solvents formed of HFC-227 (heptafluoropropane) and a solvent selected from HFC-125 (pentafluoroethane) and FC-218 (perfluoropropane), in a volumetric ratio HFC 125 (or FC 218)/HFC 227 between 90/10 and 10/90 in the presence of a regulating transfer agent.