| 摘要 |
PURPOSE:To obtain a polycarbonate diol which gives a polyurethane wherein the formation of ether linkages is suppressed and the physical properties are not lowered, by subjecting ethylene carbonate to ester interchange with diol with the concentration of ethylene carbonate controlled to a specified value. CONSTITUTION:The manufacture of a polycarbonate diol by ester interchange of ethylene carbonate with diol, is carried with the concentration of ethylene carbonate in the reaction solution during the reaction period controlled so as not to exceed 25wt.%. Ethylene carbonate that is a raw material is a compound which has a melting point of 36.4 deg.C and is crystalline at ordinary temperatures. The supply of this compound into a reactor can be carried out in a state of crystals, but it is preferred that the compound is heated and melted previously and then supplied. As the diol that is the other raw material, preferably 1,6- hexanediol, cyclohexane-1,4-dimethanol, etc. are included. The final proportion of diol and ethylene carbonate in all to be supplied is of the order of 1/10-10/1 in molar ratio, and the molar ratio is preferably in the range of 1/1.5-1.5/1 from an economical point of view.
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