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Lactide combined purification method

A purification method and lactide technology, applied in the direction of organic chemistry, can solve the problems of long crystallization period of solvents, not suitable for large-scale production, pollution of the environment, etc., and achieve the effect of shortening the purification period

Active Publication Date: 2012-12-12
武汉三江航天固德生物科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to provide a coupling purification method of lactide, which can solve the problems of long cycle of solvent crystallization, environmental pollution, and unsuitability for large-scale production

Method used

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Effect test

Embodiment approach

[0017] Overall implementation of the present invention is as follows:

[0018] 1. A coupling purification method of lactide, mainly comprising the following steps:

[0019] 1) weighing, taking lactide, its purity is 85%~94%;

[0020] 2) Rectification, the rectification pressure is controlled at 1kPa~10kPa, and the rectification temperature is controlled at 130°C~165°C;

[0021] 3) Collect 1, collect fractions, and control the temperature of fractions at 118°C to 122°C;

[0022] 4) Crystallization, carry out non-solvent crystallization, feed at 95°C~105°C, control the crystallization temperature at 97°C~97.5°C, and control the crystallization time at 50min~70min;

[0023] 5) Collect 2, the collection purity is 99.5% lactide.

[0024] The lactide is a left-handed lactide.

[0025] The rectification pressure range is preferably 3kPa~8kPa.

[0026] The rectification temperature is preferably 140°C to 150°C.

Embodiment 1

[0028] 1) Weighing, taking by weighing 200Kg of left-rotating lactide with a purity of 94%;

[0029] 2) Rectification, the rectification pressure is controlled at 1kPa, and the rectification temperature is controlled at 130°C;

[0030] 3) Collect, collect fractions, and control the temperature of fractions at 118°C~122°C;

[0031] 4) Crystallization, feed at 95°C, control the crystallization temperature at 97°C~97.5°C, and control the crystallization time at 50min;

[0032] 5) For the finished product, 99.5% pure lactide is collected to obtain 90Kg, and the remaining low-purity lactide enters the rectification process for recycling.

Embodiment 2

[0034] 1) Weighing, weighing 200Kg of left-rotating lactide with a purity of 94%;

[0035] 2) Rectification, the rectification pressure is controlled at 10kPa, and the rectification temperature is controlled at 165°C;

[0036] 3) Collect, collect fractions, and control the temperature of fractions at 120°C~122°C;

[0037] 4) Crystallization, feed at 105°C, control the crystallization temperature at 97°C~97.3°C, and control the crystallization time at 70min;

[0038] 5) For the finished product, 99.5% pure lactide is collected to obtain 92Kg, and the remaining low-purity lactide enters the rectification process for recycling.

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Abstract

The invention discloses a lactide combined purification method and belongs to the field of lactic acid manufacture. The lactide combined purification method comprises the following steps of weighing low-purity lactide, carrying out rectification, collecting fractions, carrying out non-solvent crystallization, and collecting lactide having purity of 99.5%. The lactide combined purification method adopts a high-vacuum rectification and non-solvent crystallization combined technology, solves the problem that only a high-vacuum rectification technology further improves lactide purity difficultly, and further realizes purification effects by a non-solvent crystallization process. Through the lactide combined purification method, lactide purity reaches to above 99.5%. The rest of low-purity lactide can be distilled sequentially. The lactide combined purification method shortens a purification period, avoids use of a large amount of a solvent and is suitable for large-scale production.

Description

technical field [0001] The invention belongs to the field of lactic acid production, and in particular relates to a lactide coupling purification method. Background technique [0002] Lactide is an important compound that can be used to prepare polylactic acid and its copolymers, and its purity has a direct impact on whether polylactic acid with high relative molecular weight can be synthesized. When the lactide purity index does not meet the specified requirements, only polylactic acid with a relatively low molecular weight can be obtained, which has no application value. Therefore, lactide purification method has been considered as a key technology of polylactic acid synthesis technology. [0003] The purification methods of lactide are generally divided into three types: recrystallization method, gas-assisted evaporation method and hydrolysis method. Recrystallization is currently the most commonly used lactide purification method. Patent documents with application num...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D319/12
Inventor 谢剑宏刘俊飞赵文胜徐仁义梁庭德
Owner 武汉三江航天固德生物科技有限公司
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