Method for preparing lactide

Abstract

The invention refers to a method for producing lactide. The character lies in: under the protection of inert gas, the invention uses instillation to eliminate the water in lactic acid, then uses an azeotropic solvent which can make the condensation reaction advantage to generate lactide, the solvent is good solvent to lactide and the bad solvent to lactic acid polymer, the solvent flows back in the protection of inert gas continuously, make the lactic acid is condensed into lactide, then decompression distillation is carried on, through recrystallization there gets the high purity lactide.

Description

[technical field]

[0001] The invention relates to the field of chemistry, in particular to a method for preparing lactide. [technical background]

[0002] Polylactic acid is a synthetic polymer compound that is completely biodegradable. Since the raw material lactic acid can be produced by fermentation of agricultural products, it is considered to be a sustainable and environmentally friendly compound. And because polylactic acid has good biocompatibility, the intermediate product of metabolism in the body is lactic acid, the normal metabolite of sugar, and the final metabolites are carbon dioxide and water. Therefore, polylactic acid has broad research and application prospects as the mechanism material of drug controlled release system, surgical suture, tissue engineering scaffold material and bone repair material.

[0003] Generally, there are two routes for the preparation of polylactic acid, namely direct polycondensation method and ring-opening polymerization method....