| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a purified polyalkylene glycol, with which low-molecular compounds such as water, ethylene glycol, diethylene glycol, a lower aldehyde, etc., are removed from a crude polyalkylene glycol in a large amount. SOLUTION: A polyethylene glycol having 200-10,000 molecular weight is defoamed and subjected to thin film evaporation so that impurities having molecular weight not more than the molecular weight of diethylene glycol are removed to give a purified polyalkylene glycol. The temperature of the defoaming is≥100°C and≤220°C and the pressure is≥13.3 Pa and≤4,000 Pa. The temperature of the thin film evaporation is≥100°C and≤250°C and the pressure is >1.33 Pa and≤13.3 Pa. COPYRIGHT: (C)2005,JPO&NCIPI
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