Patent ID: 6395938
Filing Date: 2002-05-28
Classification: C08G

Abstract:
A method for controlling the molecular weight distribution of polyether glycol obtained in producing polyether glycol having a specified number average molecular weight by polymerizing tetrahydrofuran as a starting monomer with the use of a heteropoly-acid as a catalyst, without substantially changing the average molecular weight which method comprises conducting the polymerization in the presence of an amount of water which can form two phases of an organic phase and a catalyst phase, sampling the polymerization product during the polymerization to determine the molecular weight distribution and, when the molecular weight distribution thus found is narrower than the specified molecular weight distribution, making the residence time distribution of the starting monomer in the catalyst phase greater, while, when the found molecular weight distribution is wider than the specified molecular weight distribution, making the residence time distribution of the starting monomer in the catalyst phase less, wherein the residence time distribution in the catalyst phase of the starting monomer is controlled by varying the tetrahydrofuran residence time in the reaction vessel V/F, wherein V is the total liquid volume in the reaction vessel and F is the rate of monomer feed to the reaction vessel, V/F being increased when the molecular weight distribution of the polymer is to be widened, while V/F being decreased when the molecular weight distribution is to be narrowed.