A method for removing pigment and impurities in crude lactide

A technology for lactide and impurities, applied in the fields of organic chemistry, products, reagents, etc., can solve the problem of a large number of theoretical plates, achieve good removal effect, reduce operating temperature and operating difficulty, and improve product quality.

Active Publication Date: 2021-03-05
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, it is difficult to achieve an excessively high vacuum degree in actual operation, and because the boiling points of the components are close, the number of theoretical plates required is also large.

Method used

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  • A method for removing pigment and impurities in crude lactide

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] Preparation of crude L-lactide: using zinc oxide and stannous octoate as catalyst, 88% L-lactic acid as raw material, after dehydration, polycondensation and depolymerization of lactic acid, the crude L-lactide with a purity of 85.7% was obtained, wherein, meso-lactide ( m -Lactide) content is 5.7%, lactic acid content is 6.3%, lactic acid dimer, trimer content is 1.8%, also includes a small amount of water and other impurities.

[0034] Take 5000 g of the above-mentioned crude L-lactide, grind it to 35-100 mesh with a pulverizer, and put it into a crude lactide storage tank. Before feeding materials, the temperature and pressure of the rectification tower need to be increased. The temperature of the rectification tower is set in three sections. When the pressure in the rectification tower reaches 10MPa, the temperature of the three-stage packing reaches 36°C from bottom to top. At 60°C and 80°C, the supercritical CO 2 Sent into the rectification tower, the supercriti...

Embodiment 2

[0037] Preparation of crude L-lactide: Zinc oxide and stannous octoate are used as catalysts, lactate is used as raw material (self-made, mass fraction 92%), lactate is dehydrated and dealcoholized first, and then oligomers are formed by polycondensation Lactic acid ester is depolymerized at high temperature to obtain crude L-lactide with a purity of 83.1%. in, m -The content of lactide is 6.2%, the content of lactic acid is 4.7%, the content of dimer and trimer lactate is 2.9%, and it also includes a small amount of water and other impurities.

[0038] Take 5000 g of the above-mentioned crude L-lactide, heat and melt at 98°C. Before feeding materials, the temperature and pressure of the rectification tower need to be increased. The temperature of the rectification tower is set in three sections. When the pressure in the rectification tower reaches 10MPa, the temperature of the three-stage packing reaches 36°C from bottom to top. At 60°C and 80°C, the supercritical CO 2 Sen...

Embodiment 3

[0041] Preparation of crude L-lactide: using zinc oxide and stannous octoate as catalyst, 88% L-lactic acid as raw material, after dehydration, polycondensation and depolymerization of lactic acid, the crude L-lactide with a purity of 85.7% was obtained, wherein, meso-lactide ( m -Lactide) content is 5.7%, lactic acid content is 6.3%, lactic acid dimer, trimer content is 1.8%, also includes a small amount of water and other impurities.

[0042] Take 5000 g of the above-mentioned crude L-lactide, grind it to 35-100 mesh with a pulverizer, and put it into a crude lactide storage tank. The temperature and pressure of the rectification tower need to be raised before feeding the material. The pressure in the rectification tower is 9MPa, and the temperature of the rectification tower is gradually raised from the bottom to the top of the tower, that is, from 40°C to 60°C. Supercritical CO 2 Sent into the rectification tower, the supercritical CO entering the rectification tower 2 T...

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Abstract

The invention relates to a method for removing pigments and impurities in crude lactide. First, the temperature and pressure in the rectification tower are adjusted, and supercritical CO 2 into the rectification tower; then the crude lactide is crushed or heated and melted, and then sent into the rectification tower for decolorization and impurity removal; the product after rectification and CO 2 Separation to obtain de-impurity and decolorized lactide. The present invention uses supercritical CO 2 The combination of extraction and rectification process can not only effectively remove the pigment and impurities in the crude lactide, but also effectively reduce the operating temperature and difficulty of the rectification process, and reduce the coking, oxidation and polymerization of lactide caused by high temperature And side reactions such as mesization, to ensure the yield and quality of lactide products, is a purification method with high operational feasibility, simple separation process, and high-efficiency removal of impurities.

Description

technical field [0001] The invention belongs to the technical field of polymer materials, and in particular relates to a method for removing pigments and impurities in crude lactide. Background technique [0002] Polylactic acid (PLA), with good mechanical strength, biocompatibility, biodegradability and bioabsorbability, is a green polymer material with broad application prospects and fields. With the continuous maturity of polylactic acid production technology and the continuous development of its application market, the production of polylactic acid from non-food crops → lactic acid → polylactic acid has begun to enter the period of industrialization development. Natureworks of the United States is currently the largest polylactic acid producer in the world, with a production capacity of 140,000 tons, of which L-lactide production capacity has reached 150,000 tons. It is estimated that by 2020, the global production capacity of L-lactide and D-lactide will exceed 500,000...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D319/12
CPCC07D319/12Y02P20/141Y02P20/54
Inventor 孙启梅彭绍忠高大成王鹏翔姚新武朱化雷
Owner CHINA PETROLEUM & CHEM CORP
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