| 摘要 |
<p>The invention describes a process for the preparation of polycarbonate copolyester diols with a molecular weight ranging between 1000 and 6000 units having the following general formula: <CHEM> wherein the polycarbonate or polyether polycarbonate diol units <CHEM> represent a proportion of between 30 and 70% by weight of the whole polycarbonate or polyether carbonate copolyester diol -- R1 is a divalent organic radical deriving from one or more polyetherglycols or aliphatic glycols containing from 4 to 20 carbon atoms; R2 is a divalent organic radical corresponding to a cyclic lactone having a ring with 4, 6, 7 atoms or an organic residue deriving from a lactide or glycolide; n and m, the same or different, can have any value between 2 and 40; said process being characterized in that cyclic esters having the formula: <CHEM> wherein R2 has the meaning defined above, are reacted with polycarbonate or polyethercarbonate diols having the formula: <CHEM> wherein R1 and m have the meaning defined above, at a temperature RANGING between 100 DEG and 180 DEG C and for a time between 2 and 10 hours.</p> |
