Patent ID: 7288682
Filing Date: 2007-10-30
Classification: C08G

Abstract:
1. A process for separating bifunctional perfluoropolyethers having two methylol terminations —CH 2 OH from their mixtures with monofunctional perfluoropolyethers with one methylol termination —CH 2 OH, optionally containing perfluoropolyethers with non functionalized end groups, having general formula wherein: comprising the following steps: a) addition of the perfluoropolyether mixture to an adsorbing solid phase, optionally dispersed in an apolar solvent, contained in a reactor equipped with stirring, with a mixture/solid phase ratio from 0.1 to 10 w/w, leaving under stirring for a time between 15 minutes and 6 hours at a temperature between 10° and 150° C.; b) filtration of the mixture obtained from step a), with separation of a solid phase containing adsorbed perfluoropolyether mixture enriched in bifunctional perfluoropolyethers and a liquid containing a perfluoropolyether mixture having diminished bifunctional species; c) addition to the solid phase obtained in b), of a perfluoropolyether mixture having an average functionality higher than that of the perfluoropolyether mixture of the liquid obtained in b), in a mixture/solid phase ratio between 0.1 and 2 w/w, optionally together with an apolar solvent, leaving under stirring for a time between 15 minutes and 6 hours, at a temperature between 10° and 150° C.; c1) optional repetitions of the operations of steps b) and c), until reaching the desired high functionality of the adsorbed perfluoropolyether; c2) filtration to separate the adsorbing solid phase from the liquid; d) addition to the solid phase separated in c2) containing adsorbed the perfluoropolyether having the desired high functionality, of a polar solvent in an amount of 1-10 w/w, stirring at 5°-150° C.; e) filtration of the mixture resulting from step d) with separation of a liquid containing the perfluoropolyether having the desired high functionality which is then isolated from the solvent.