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Reaction process for preparing low-acid lactide

A lactide and reaction technology, which is applied in the field of reaction technology for preparing low-acid fraction lactide, can solve the problems of large equipment investment, high production cost, complicated process, etc., and achieves reduction of energy consumption and equipment investment, and reduction of production units. Consumption and production costs, the effect of simplifying the process

Pending Publication Date: 2021-03-12
WANHUA CHEM (SICHUAN) CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Although the existing disclosed technology has solved the problem of lactide impurity separation and control to a certain extent, there are still problems such as complicated process, large equipment investment, and high production cost. In the technical field of preparing low acid value and high purity lactide, there is still New process method is needed

Method used

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  • Reaction process for preparing low-acid lactide
  • Reaction process for preparing low-acid lactide
  • Reaction process for preparing low-acid lactide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Use as attached figure 2 In the process shown, the prepolymerization adopts a batch stirred tank, lactic acid is used as raw material, the control system pressure is 1kPa, the reaction temperature is gradually increased to 150°C, and the temperature is kept for 1.5h. The reaction product lactic acid oligomer Mw=806.

[0038] The first depolymerization reactor adopts a POPE scraper evaporator, the residence time is 2s, the reaction temperature is controlled at 170°C, the pressure is 5kPa, the scraper speed is 400 rpm, the gas phase components are condensed and recycled to the prepolymerization step for use, and the liquid phase products Send to the II depolymerization reactor. The second depolymerization reactor is a tubular falling film evaporator, the reaction temperature of the second depolymerization reactor is controlled at 200°C, the pressure is 0.5kPa, the feed rate is about 3kg / h, and the crude lactide is obtained in the gas phase of the second depolymerization...

Embodiment 2

[0041] Use as attached figure 2 Shown flow process, equipment are the same as embodiment 1. The pre-polymerization adopts batch stirring tank, lactic acid is used as raw material, the pressure of the control system is 20kPa, the reaction temperature is gradually increased to 150°C, and the temperature is kept for 4h. The reaction product lactic acid oligomer Mw=810.

[0042] Depolymerization I uses a POPE scraper evaporator, the residence time is 2s, the reaction temperature is controlled at 180°C, the pressure is 1kPa, the scraper speed is 400 rpm, the gas phase components are condensed and recycled to the prepolymerization step, and the liquid phase products are sent to the second stage. Depolymerization reactor. Depolymerization II is a tubular falling film evaporator. Control the reaction temperature of the depolymerization II reactor at 200°C, the pressure of 0.5kPa, and the feed rate of about 3kg / h. The crude lactide product is obtained in the gas phase of the second ...

Embodiment 3

[0045] Use as attached figure 2 Shown flow process, equipment are the same as embodiment 1. The pre-polymerization adopts a batch stirring tank, lactic acid is used as raw material, the pressure of the control system is 2.5kPa, the reaction temperature is gradually increased to 150°C, and the temperature is kept for 2h. The reaction product lactic acid oligomer Mw=790.

[0046] Depolymerization I uses a POPE scraper evaporator, the residence time is 30s, the reaction temperature is controlled at 190°C, the pressure is 1kPa, the scraper speed is 400 rpm, the gas phase components are condensed and recycled to the prepolymerization step, and the liquid phase products are sent to the second stage Depolymerization reactor. Depolymerization II is a tubular falling film evaporator. The reaction temperature of the depolymerization II reactor is controlled at 200°C, the pressure is 0.5kPa, and the feed rate is about 3kg / h. The gas phase components are condensed and recycled to the p...

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Abstract

The invention discloses a reaction process for preparing low-acid lactide. According to the process, lactic acid is pre-polymerized and cracked to prepare lactide, the raw material polylactic acid passes through at least two depolymerization reaction zones, the single-pass conversion rate of the depolymerization reaction is controlled to be not higher than 10% in the first depolymerization reaction zone, and a gas-phase product is circulated to an upstream polylactic acid preparation procedure; and the liquid-phase product passes through a subsequent depolymerization reaction zone to obtain acrude lactide product. By adopting the process, the acid content of crude lactide can be remarkably reduced, impurities are reduced, byproducts are reduced, and downstream separation energy consumption and production cost are remarkably reduced.

Description

technical field [0001] The invention belongs to the field of lactide, in particular to a reaction process for preparing low-acid lactide. Background technique [0002] Polylactic acid (PLA), also known as polylactide, is a typical biodegradable polymer material prepared by chemical synthesis from renewable plant resources. At present, the PLA global market is growing rapidly, and the annual demand will increase at a rate of 20,000 to 30,000 tons. The premium can reach 20%-30%, and it is expected that the supply will be in short supply for a long time. The largest application field of PLA is food packaging, accounting for more than 65%, and the second largest application field is textile fiber. The global plastic ban and garbage sorting have brought a huge potential market for degradable plastics, especially disposable plastic products. [0003] At present, the industrial production of PLA generally adopts the lactide ring-opening polymerization method. Lactide is the key i...

Claims

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Application Information

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IPC IPC(8): C07D319/12
CPCC07D319/12
Inventor 何岩杨颖田博刘英俊张红涛朱小瑞马朋成张永振乔小飞
Owner WANHUA CHEM (SICHUAN) CO LTD
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