Coupling refining method of high-purity L-lactide

A lactide and crystallizer technology, applied in the direction of organic chemistry and the like, can solve the problems of increasing the difficulty of process operation and operation cost, and achieve the effects of simple equipment and process, less process pollution and low operation cost.

Inactive Publication Date: 2013-06-12
TIANJIN UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since rectification needs to be operated in a high temperature area, this increases the difficulty and operating cost of the process operation to a certain extent
At the same time, lactide is easy to react in the high temperature area, which may introduce new impurity components in the purification process

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0023] Dissolve 96.2g of crude L-lactide with a purity of 80.5% in 200g of ethanol solution at a temperature of 60°C, add 1% seed crystals, and start to cool down at a cooling rate of 0.33°C / min after growing the crystals for 30 minutes. 10°C, vacuum filtration and drying to obtain lactide crystals with a purity of 98.5%; heat up and melt the lactide with a purity of 98.5%, then add it to a melting crystallizer at a temperature of 90°C for film-hanging treatment, and grow crystals for 30 minutes Finally, cool down to 75°C at a rate of 4°C / h and grow crystals for 30 minutes; discharge the crystallized residual leaves for sweating operation, the heating rate is 4°C / h, and the final temperature of sweating is 87°C. After sweating, the temperature of the crystals was raised to 97° C. and melted to obtain 49.2 g of L-lactide with a purity of 99.91%.

example 2

[0025] Dissolve 76.4g of crude L-lactide with a purity of 80.9% and 20.0g of molten crystal sweating solution in 220g of ethanol solution at a temperature of 60°C, add 0.8% seed crystals, and grow the crystals for 30 minutes at a rate of 0.25°C / min. The cooling rate starts to drop the temperature down to 8°C, vacuum filtration and drying to obtain lactide crystals with a purity of 98.8%. The lactide with a purity of 98.8% was heated and melted, and then added to a melting crystallizer at a temperature of 91°C that had undergone film-hanging treatment. After 40 minutes of crystal growth, the temperature began to drop at a rate of 3.5°C / h. After cooling down to 75°C, grow crystals for 40 minutes, and then discharge the crystallized residual leaves for sweating operation. The heating rate is 5°C / h, and the final sweating temperature is 85°C. After sweating, the temperature of the crystal was raised to 97° C. and melted to obtain 52.6 g of L-lactide with a purity of 99.95%.

example 3

[0027] Dissolve 63.4g of crude L-lactide with a purity of 81.2% in 200g of ethanol solution at a temperature of 50°C, add 0.8% seed crystals, and start cooling at a cooling rate of 0.2°C / min after growing the crystals for 30 minutes, down to 15°C, vacuum filtration and drying to obtain lactide with a purity of 98.9%. The lactide with a purity of 98.9% was heated and melted, and then added to a melting crystallizer at a temperature of 90°C that had undergone film-hanging treatment. After 20 minutes of crystal growth, the temperature began to drop at a rate of 4°C / h. After cooling down to 75°C, grow the crystals for 15 minutes, then discharge the residual crystallized leaves for sweating operation, the heating rate is 4°C / h, and the final sweating temperature is 87°C. After sweating, the temperature of the crystals was raised to 97° C. and melted to obtain 37.2 g of L-lactide with a purity of 99.95%.

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PUM

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Abstract

The invention provides a method for refining high-purity L-lactide by way of liquid crystallization and melt crystallization. The method comprises the following steps of: based on 80% L-lactide crude product as a raw material, initially purifying the L-lactide crude product by way of liquid crystallization; and then secondarily purifying the L-lactide by way of melt crystallization. The method specifically comprises cooling and crystallizing, melt crystallization, sweating, and melting. L-lactide with purity over 99.5% can be prepared by applying the method.

Description

technical field [0001] The purpose of the present invention is to provide a production method of high-purity L-lactide. Background technique [0002] Polylactic acid (PLA) is a new type of ester material that can be completely biodegradable. It has good mechanical and physical properties and can replace traditional polymers derived from petroleum as a new generation of environmentally friendly polymer materials. has received widespread attention. L-lactide is an important raw material that can be used to prepare polylactic acid, and its purity directly determines the quality of polylactic acid. Only when the purity of lactide reaches a certain requirement can it be used as a raw material to synthesize valuable polylactic acid. Therefore, the purification method of lactide has been considered as a key link in the production process of polylactic acid. [0003] The traditional purification methods of L-lactide are mainly divided into three categories: gas-assisted evaporati...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D319/12
Inventor 朱亮沙作良王彦飞杨立斌刘跃文
Owner TIANJIN UNIV OF SCI & TECH
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