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Method for refining lactide

A technology of lactide and fractionation, applied in the direction of organic chemistry, can solve the problems of low lactide, high yield, difficult operation, etc.

Inactive Publication Date: 2010-02-03
TATE & LYLE TECH LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, such a top-mounted three-component separation system is very difficult to operate, especially in view of the fact that the system is located on top of the reactor, and it is difficult to imagine that a lactide with an acid content low enough to produce HMW-PLA can thus be obtained. high yield

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0074] Embodiment 1. The influence of lactic acid impurity on polylactic acid molecular weight

[0075] The molecular weight of polylactic acid is controlled by the amount of hydroxyl impurities in lactide. Lactide with different concentrations of lactic acid and lactic acid oligomers (meq / kg) was polymerized into polylactic acid to illustrate the effect of these impurities on molecular weight. Polymerization was carried out at 180° C. using 0.1 wt. % stannous octoate as catalyst under an inert atmosphere.

[0076] Lactic acid impurity (meq / kg)

Embodiment 2

[0077] Embodiment 2. crude lactide

[0078] Low molecular weight poly(L-lactic acid) (250-300 g) was charged at room temperature into a specially designed laboratory distillation apparatus for the production of crude lactide. The apparatus consists of a 3-neck flask (500ml) with a large magnetic stirring bar and a heated oil bath (210-230°C), a vigreux column wrapped around a controlled heating tape (140-170°C), an insulating tape and a 3-flask sample Composition of the collection system. A vacuum of 30 mbar was maintained for crude lactide production and evaporation. Distilled fractions of crude lactide were collected for 1-2 hours. The solidified crude lactide fraction was retained for analysis of free acid, water and composition. The composition of the analyzed crude lactide is given in the table below together with the molecular weight of the low molecular weight polylactic acid. As can be seen from the free acid content and water content, high molecular weight polyl...

Embodiment 3

[0080] Embodiment 3. crude lactide

[0081] Crude lactide was continuously produced in a stirred tank reactor by continuous addition of low molecular weight poly(D,L-lactic acid). The vaporous crude lactide produced enters a column with a partial condenser. The column is mounted directly on the reactor. At the top of the column, after the condenser, water, lactic acid and some lactide are removed. The liquefied crude lactide fraction is removed in the lower part of the column. Analyze this fraction. The reaction mass was 26 kg and the temperature and pressure were kept constant during the process. The results of continuous crude lactide production are given in the table below.

[0082] Example

[0083] a Determined by NMR.

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PUM

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Abstract

The present case relates to a process for the purification of lactide from a crude lactide vapour product stream which process comprises a rectification / condensation step leading to a lactide-enrichedcondensate.

Description

technical field [0001] The present invention relates to an improved process for refining lactide from a crude lactide vapor product stream comprising at least lactide, lactic acid, water and linear lactic acid oligomers. Background technique [0002] Lactide is a dimeric cyclic ester of lactic acid and is an intermediate in the production process of high molecular weight (HMW) polylactic acid (PLA), which is actually a biodegradable polymer and can be used as a substitute for non-biodegradable polymers. substitution. The use of lactic acid and lactide for the manufacture of biodegradable polymers, such as those used in the manufacture of biodegradable sutures, clamps, bone plates and bioactive controlled release devices, is well known in the biomedical industry. [0003] Lactide is most conveniently produced by a two-step polymerization / depolymerization process. First, lactic acid from a feed source is polymerized into relatively low molecular weight (oligomer) polylactic ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C55/28C07D319/12
CPCC07D319/12
Inventor 约翰尼斯·米尔迪克尼尔斯·丹·安德斯·索德卡德
Owner TATE & LYLE TECH LTD