Method for fractioning poly (ethylene oxide) formed using a metallic cyanide catalyst
AssigneeThe Dow Chemical Company
InventorsKatherine S. Clement, Louis L. Walker
Life of this patent
Estimating the term…
Abstract
A poly(ethylene oxide) polymer having low and high molecular weight fractions is fractionated by dissolving the polymer in a solvent for the low molecular weight fraction. A good separation of the low and high molecular weight fractions can be obtained. When the poly(ethylene oxide) polymer contains a metal cyanide catalyst, this process also provides a good separation of the catalyst from the low molecular weight fraction. In this instance, the catalyst remains active and the high molecular weight fraction containing the catalyst can be recycled into subsequent polymerization processes.
Claims21
A method for purifying a poly(ethylene oxide) polymer containing a lower molecular weight fraction, and at least one higher molecular weight fraction, comprising
- (a) mixing:
- (1) said poly(ethylene oxide) polymer, and
- (2) a solvent or mixture of solvents, said solvent or mixture of solvents, being a solvent for said low molecular weight fraction but not for said high molecular weight fraction,
- in relative amounts and under conditions such that a solution of said low molecular weight fraction in said solvent or mixture of solvents forms;
- and
- (b) separating said solution from said high molecular weight fraction.
A method for removing a metal cyanide catalyst from a poly(ethylene oxide) polymer containing a metal cyanide catalyst, a lower molecular weight fraction and at least one higher molecular weight fraction, the method comprising
- (a) mixing:
- (1) said poly(ethylene oxide) polymer, and
- (2) a solvent or mixture of solvents, said solvent or mixture of solvents being a solvent for said low molecular weight fraction but not for said metal cyanide catalyst or said high molecular weight fraction;
- in relative amounts and under conditions such that a solution of said low molecular weight fraction in said solvent or mixture of solvents forms and
- (b) separating said solution from said high molecular weight fraction and said metal cyanide catalyst, and
- (c) recovering said low molecular weight fraction from said solution.
Dependencies are inferred from the claim text.