Patent ID: 8653229

Claim:
Process for the oligomerization of hexafluoropropylene oxide (HFPO) in which the sum of the dimers, trimers, tetramers, pentamers and hexamers represents less than 20% of the weight of the polymerized HFPO, the oligomers other than the dimers, trimers, tetramers, pentamers and hexamers having an average molecular weight ranging between 1100 and 4000 g/mol, comprising the steps of contacting hexafluoropropylene oxide at a temperature ranging between −30° C. to +50° C. with a catalytic system formed from potassium fluoride (KF) with a glycol ether in the presence of a solvent, wherein the solvent is a perfluorinated saturated aliphatic or aromatic hydrocarbon with more than 3 and less than 12 C-atoms and optionally a polar group but not comprising chlorine or bromine or partially fluorinated saturated aliphatic or aromatic hydrocarbon with more than 3 and less than 12 C-atoms and optionally a polar group but not comprising chlorine or bromine at a pressure of less than 5 bars by controlled, continuous controlled monomer addition or by adding the hexafluoropropylene oxide in one or two portions, wherein the process is performed in the absence of hexafluoropropylene (HFP).