| 摘要 |
PURPOSE:To provide a lactide low in hygroscopicity and useful as a raw material for polylactic acid. CONSTITUTION:The lactide free from water and low in hygroscopicity. The objective lactide is produced by the steps of dissolving calcium lactate in the mixture of concentrated hydrochloric acid with crushed ice; subjecting the solution to a countercurrent extraction using butanol; subjecting the extract to a dehydrative reaction and to an esterification reaction; and subsequently heating the continuously produced butyl lactate in the presence of transesterification catalyst (preferably dibutyl stannic dichloride, dibutyl stannic lactate, zinc dichloride, stannic tetrachloride, phosphoric acid, para-toluenesulfonic acid) under atmospheric pressure or a reduced pressure, while distilling out the by-produced butanol. |
