PURPOSE: To increase the rate of sedimentation of an alkali catalyst and to separate and remove the catalyst in a polyether by a simple operation efficiently, by adding a dissolution solvent to the polyether containing the alkali catalyst and separating the catalyst in the vicinity of the critical state of the solvent by gravitational sedimentation.
CONSTITUTION: A polyether 1 synthesized in the presence of an alkali catalyst is blended with a dissolution solvent 2 such as n-hexane, etc., and the catalyst is separated 4 by gravitational sedimentation in the vicinity of the critical state of the solvent. Consequently part of the polyether is selectively aggregated on particles of the catalyst, the particle size of the catalyst is enlarged so the catalyst 5 is readily removed from a mixed solution 6 of the polyether and the dissolution solvent. Further the dissolution solvent 2 is separated 7 by evaporation separation method, etc., from the mixed solution 6 to obtain the purified polyether 8 containing no catalyst at low cost and in high quality without requiring complicated operations.
MAKIHARA HIROSHI
NAKAMOTO AYAO
HORII KEISUKE
SANYO CHEMICAL IND LTD