| 摘要 |
1,263,225. Aliphatic polycarbonates. FARBENFABRIKEN BAYER A.G. 25 March, 1970 [28 March, 1969], No. 14487/70. Heading C3R. Hydroxyl terminated aliphatic polycarbonates having M.Wts. from 600-5000 and a total phenol content of not more than 0À15% by weight, are obtained by (a) in a first stage reacting at least one dihydric alcohol and diphenylcarbonate at 100-170‹ C. under reduced pressure until more than 90% of the theoretical amount of phenol has been removed, (b) in a second stage completing the polycondensation at 170-205‹ C. and (c) if necessary removing the residual phenol at 180-205‹ C. under reduced pressure. In a further embodiment step (c) is carried out by passing an inert gas (e.g. CO 2 ) through the product under reduced pressure. In the examples diphenyl carbonate is reacted with (a) hexane-1,6-diol, (b) mixed o-(2-hydroxyethyl) - hexane - 1,6 - diol-hexane - 1,6 - diol, (c) as (b) with trimethylolpropane, (d) diethylene glycol and (e) triethylene glycol. |
