Polymerisation of hexafluoropropylene oxide
View Patent ↗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 (the remaining oligomers) having an average molecular weight ranging between 1100 and 4000 g/mol, characterized in that the process comprises the steps of contacting hexafluoropropylene oxide (HFPO) at a temperature between −30° C. to +50° C. with a catalyst system selected from potassium fluoride and di-, tri- or tetraethyleneglycol-dimethylether in the presence of a solvent which is selected from perfluorinated 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 partially fluorinated 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 3 bars by controlled monomer addition continuous feeding or by adding the monomer in one or two portions (shots).
1. 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).
2. A process according to claim 1 , wherein the solvent is not fully fluorinated and the solvent contains an aromatic group, an ether or an ester group.
3. A process according to claim 2 , wherein the solvent is selected from the group consisting of nonafluorobutyl-methylether, 1,3-bis-(trifluoromethyl)-benzene and 1,1,1,3,3-pentafluorobutane.
4. A process according to claim 1 , wherein the process is carried out at temperatures ranging between −20° C. and +20° C.
5. A process according to claim 1 , wherein the process is carried out by continuous controlled monomer addition.
6. A process according to claim 1 , wherein the process is carried out with a weight ratio of the di-, tri- or tetraethyleneglycol-dimethylether and the potassium fluoride ranging between 1.0 and 10.0.
7. A process according to claim 2 , wherein the process is carried out with a weight ratio of the perfluorinated solvent and the di-, tri- or tetraethyleneglycol-dimethylether ranging between 1 and 25.
8. An oligomerized hexafluoropropylene oxide made in accordance with the process of claim 1 .