Process for the preparation of polyether glycol

Abstract

In the process for preparing polyether glycol comprising (A) polymerizing tetrahydrofuran or a mixture of tetrahydrofuran and other copolymerizable cyclic ether(s) in the presence of a ring-opening polymerization catalyst comprising fuming sulfuric acid and/or fluorosulfuric acid as principal component, (B) adding water or an aqueous alkali solution to the polymerization product, and heating said reaction product under the strongly acidic condition to hydrolyze the same and (C) washing the hydrolysis product comprising polytetramethylene glycol and polyether glycol having oxytetramethylene groups as principal constituent, the polymerization of the tetrahydrofuran or the mixture of tetrahydrofuran and other copolymerizable cyclic ether(s) in the (A) step is carried out by (1) contacting the same with a ring-opening polymerization catalyst at a temperature within the range of -30.degree. C. to 10.degree. C. in the first stage, and (2) elevating the reaction temperature, when the conversion of said monomer into the polymer has reached 5% or more, to a temperature which falls within the range of 0.degree. C. to 40.degree. C. and is at least 10.degree. C. higher than the reaction temperature in the first stage and continuing the polymerization at this temperature. This process enables the effective and easy preparation of a highly functional polyether glycol having a relatively low molecular weight of about 500 to 5,000 and comprising oxytetramethylene groups as principal constituent, said polyether glycol being useful as a starting material for the preparation of polyurethanes, elastomeric polyesters, elastomeric polyamides and the like.