| 摘要 |
A method for producing a medium-molecular weight polyalkylene oxide having a viscosity-average molecular weight of from 100,000 to 2,500,000, including heat-treating a polyalkylene oxide having a viscosity-average molecular weight of 3,000,000 or more at a temperature of from 30° to 70°C in an aliphatic hydrocarbon solvent having a dissolved oxygen concentration of 0.5 mg/L or more, in the presence of a radical initiator in an amount of from 0.001 to 1 part by mass, based on 100 parts by mass of the polyalkylene oxide, and thereafter adding an antioxidant to a mixture in an amount of from 0.001 to 5 parts by mass, based on 100 parts by mass of the polyalkylene oxide to remove the solvent. According to the method of the present invention, a medium-molecular weight polyalkylene oxide having a viscosity-average molecular weight of from 100,000 to 2,500,000 which has excellent storage stability can be industrially obtained without subjecting to a gamma-ray irradiation treatment. |
