| 摘要 |
PURPOSE:To prevent the thermal discoloration of polyethylene glycol (PEG) without using a stabilizer, by treating PEG synthesized in the presence of an alkali catalyst with an alkali adsorbent, adding an acid to the system, mixing with a neutral solution of ethanol and water, and adjusting to a specific pH. CONSTITUTION:A PEG preferably having a molecular weight of 200-6,000 and prepared by adding ethylene oxide to ethylene glycol, etc. in the presence of an alkali catalyst such as NaOH, is treated with an alkali adsorbent such as magnesium silicate to adsorb and remove said catalyst, and the product is filtered and then added with a slight amount (e.g. 10<-6>-10<-4>mol per 1,000mol of PEG) of an acid such as sulfuric acid. Separately, ethanol is mixed with distilled water at a volume ratio of 8:2 and adjusted to 7.0pH with NaOH. The former solution is mixed with the latter solution at a volume ratio of 1:1 and adjusted to 4.0- 7.0pH at 25 deg.C.
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