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Purification method of crude lactide and application

A purification method and crude lactide technology are applied in the field of polymer synthesis, which can solve the problems of environmental pollution, low production efficiency and high energy consumption, and achieve the effects of reducing cost, high yield and purity

Active Publication Date: 2019-03-01
普立思生物科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the prior art, the method of decompression and vacuuming is mostly used to remove residual solvents, which has high energy consumption, low production efficiency, and the removal efficiency needs to be improved; in addition, residual solvents are difficult to recover and pollute the environment

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0056] The invention provides a kind of preparation method of polylactic acid, comprises the following steps:

[0057] a1) mixing crude lactide with a solvent at 60-150°C to obtain a mixed solution; the solvent is selected from one or more of ε-caprolactone, δ-valerolactone and γ-valerolactone;

[0058] a2) cooling and crystallizing the mixed solution, and centrifuging to obtain purified lactide;

[0059] a3) Carry out bulk polymerization of the purified lactide in the presence of a catalyst to obtain polylactic acid.

[0060] The preparation method of polylactic acid provided by the present invention firstly obtains purified lactide according to the purification method described above, and then performs bulk polymerization of the purified lactide in the presence of a catalyst to obtain polylactic acid.

[0061] In the present invention, the content of the step of obtaining purified lactide is as described above, and will not be repeated here. In the embodiment of the prese...

Embodiment 1

[0077] In crude glycolide, the content of glycolide was 96.5 wt%, the content of hydroxy acid and oligomeric hydroxy acid was 3.5 wt%, and the content of free carboxyl group was 380 mmol / kg.

[0078] Add 100 g of crude glycolide and 100 g of ε-caprolactone into a sealed, clean and dry three-neck flask equipped with a thermometer, and heat to 100°C to completely dissolve the crude glycolide in ε-caprolactone to 20°C / min Cool to 20°C, glycolide crystallizes out, then cool at 20°C for 0.3h, remove the supernatant by decantation, and then centrifuge at 3000 rpm for 30min to remove residual ε-hexyl Ester mother liquor to obtain purified glycolide.

[0079] After testing, it can be seen that the content of glycolide in the purified glycolide is 98.5wt%, glycolic acid and oligoglycolic acid are 0.4wt%, ε-caprolactone residual rate is 1.1wt%, and the content of free carboxyl groups is 72.6 mmol / kg, and the yield of purified glycolide was 67.0%.

[0080] The obtained purified glycoli...

Embodiment 2

[0082] In the crude glycolide, the content of glycolide was 98.5 wt%, the content of glycolic acid and oligoglycolic acid was 1.5 wt%, and the content of free carboxyl groups was 200 mmol / kg.

[0083] Add 100 g of crude glycolide and 100 g of γ-valerolactone into a sealed, clean and dry three-neck flask equipped with a thermometer, and heat to 120°C to completely dissolve the crude glycolide in γ-valerolactone to 30°C / min Cool to 0°C, glycolide crystallizes out, then cool at 0°C for 0.6h, remove the supernatant by decantation, and then centrifuge at 3000 rpm for 30min to remove residual γ-valerolide Ester mother liquor to obtain purified glycolide.

[0084] It can be seen through testing that the content of glycolide in the purified glycolide is 99.1wt%, glycolic acid and oligoglycolic acid are 0.1wt%, the content of free carboxyl groups is 13.2mmol / kg, and the residual amount of gamma-valerolactone 0.8 wt%, the yield of purified glycolide was 81%.

[0085] The obtained puri...

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Abstract

The invention provides a purification method of crude lactide. The purification method includes the steps that A, the crude lactide and a solvent are mixed at 60-150 DEG C to obtain a mixed solution,wherein the solvent is selected from one or more of epsilon-caprolactone, delta-valerolactone and gamma-valerolactone; B, the mixed solution is subjected to cooling crystallization, and after centrifugal separation, purified lactide is obtained. The purification method can effectively remove meso-lactide and acidic impurities in the crude lactide and also can effectively remove acidic impurities in crude glycolide, the finally obtained lactide is high in purity and is polymeric lactide, and meanwhile the yield is high. Besides, the purified lactide obtained by the method can be directly polymerized without removing a trace amount of residual solvent, and the residual solvent can be effectively utilized.

Description

technical field [0001] The invention relates to the technical field of polymer synthesis, in particular to a method for purifying crude lactide and its application. Background technique [0002] Polylactic acid or polyglycolide is a degradable polyester with good mechanical strength and processability, and can partially replace traditional petroleum-based plastics. At present, polylactic acid has been produced on a large scale, and the cost is continuously reduced, and the waste polylactic acid can be biodegraded in the soil, which is expected to solve the environmental problem of "white pollution". The industrial production of polylactic acid usually prepares lactide from L-lactic acid through oligomeric dehydration and cracking, and then prepares poly-L-lactic acid by ring-opening polymerization of purified polymer-grade L-lactide. Equally, polyglycolide is prepared glycolide through cleavage of oligoglycolic acid, and glycolide is prepared high molecular weight polyglyco...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D319/12C08G63/08C08G63/78
CPCC07D319/12C08G63/08C08G63/78
Inventor 项盛冯立栋边新超陈学思李杲
Owner 普立思生物科技有限公司
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