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Method for industrial continuous preparation of high-purity lactide

A lactide, high-purity technology, applied in the direction of organic chemistry, etc., can solve the problems of inability to achieve high-purity lactide, easy to decompose, not very successful, etc., and achieve the effects of being conducive to protection, less equipment investment, and convenient operation.

Active Publication Date: 2019-05-21
北京朗净汇明生物科技有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, it still cannot meet the requirements of high-purity lactide
Multi-stage high-vacuum rectification is currently the main method used in my country's industry. Theoretically, it can achieve effective separation of high and low boiling point substances in crude lactide, but in the actual process, because crude lactide contains a certain amount of acid With water, and the heat sensitivity and reversibility of lactide under high temperature conditions will make lactide very easy to decompose; secondly, although lactide, meso, and lactic acid have a certain difference in boiling point, they are relatively close. To achieve high-purity separation under these conditions is a great challenge to equipment requirements, energy consumption, and ease of operation. Therefore, rectification technology is currently not very successful in lactide purification.

Method used

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  • Method for industrial continuous preparation of high-purity lactide
  • Method for industrial continuous preparation of high-purity lactide
  • Method for industrial continuous preparation of high-purity lactide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] The crude lactide to be treated comprises the following components in mass percentage:

[0039] Lactide 92.9%

[0040] High boilers 3.6%

[0041] Low boilers 3.5%

[0042] The evaporation equipment is a common falling film evaporator:

[0043] (1) Send the treated crude lactide into the falling film evaporator, and the material is continuously evaporated at a temperature of 160°C and a vacuum of 100Pa. The lactide evaporates rapidly under this condition, accompanied by internal The racemization, acid and water are distilled out together, and the crude lactide is collected through the first-stage condenser, and the temperature is controlled at 90°C. The crude lactide collected by the first-stage condenser is 90% of the total evaporated mass, and directly enters the melting crystallization device, melting and crystallization separation;

[0044] The temperature of the secondary condenser is 90°C, collect 10% of the total evaporation, and send it to the post-processing...

Embodiment 2

[0062] The crude lactide to be processed comprises the following components by weight percentage:

[0063] Lactide 93.8%

[0064] High boilers 3.4%

[0065] Low boilers 2.8%

[0066] The evaporation equipment is a common falling film evaporator:

[0067] (1) Send the treated crude lactide into the falling film evaporator, and the material is continuously evaporated at a temperature of 160°C and a vacuum of 100Pa. The lactide evaporates rapidly under this condition, accompanied by internal The racemization, acid and water are distilled out together, and the crude lactide is collected through the first-stage condenser, and the temperature is controlled at 90°C. The crude lactide collected by the first-stage condenser is 90% of the total evaporated mass, and directly enters the melting crystallization device, melting and crystallization separation;

[0068] The temperature of the secondary condenser is 90°C, collect 10% of the total evaporation, and send it to the post-proces...

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Abstract

The invention discloses a method for industrial continuous preparation of high-purity lactide. The method includes the following steps that of crude lactide evaporation and melt crystallization. Crudelactide evaporation includes the following steps that crude lactide is conveyed into evaporation equipment with a secondary condenser, heating and evaporation are carried out under vacuum conditions,and a lactide intermediate product with most high-boiling-point components removed is collected from a primary condenser. Melt crystallization includes the following steps that the lactide intermediate product is collected from the primary condenser and conveyed into a melt crystallizer, the melt crystallizer is used for cooling and crystallization, and mother liquor is discharged; crystals leftin the melt crystallizer are subjected to crystal sweating, and the high-purity lactide is collected. The new technology is short in process, convenient to operate, low in energy consumption and highin product yield and quality, the optical purity and chemical purity of lactide can both reach 99.6% or above, and the purification yield is 90% or above.

Description

technical field [0001] The present invention relates to the preparation method of lactide. Background technique [0002] Polylactic acid is an important biodegradable polymer with great application prospects in plastics, textiles, medical and other fields. Its raw material is lactic acid produced by biological fermentation of crops. Polylactic acid is non-toxic, non-irritating, and has good biocompatibility, and can be biodegraded and absorbed. [0003] At present, the production of polylactic acid mainly adopts a two-step process technology. The lactic acid monomer is pre-polymerized and cracked to produce crude lactide, then purified to produce lactide, and finally ring-opening polymerization to obtain high-molecular polylactic acid. In this process, the purity of lactide directly affects the quality of polylactic acid. Without high-purity lactide, qualified polylactic acid cannot be produced. There has been no effective industrialized solution for this link in China, whi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D319/12
Inventor 钱志良劳含章马谋博孙建荣
Owner 北京朗净汇明生物科技有限公司
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