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Synthesis of poly lactic acid by microwave radiation melt polycondensation method

A technology of microwave radiation and melt polycondensation, applied in the field of polylactic acid synthesis, can solve problems such as the cost reduction of polylactic acid

Inactive Publication Date: 2005-03-16
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In China, some scholars have applied microwave radiation technology to the ring-opening polymerization of polylactic acid, which has reduced the cost of polylactic acid to a certain extent; but microwave radiation has not been reported in the direct polycondensation of lactic acid; Only the Hungarian scholar Keki and others have preliminary research, and the obtained polylactic acid has a molecular weight of no more than 2000.

Method used

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Experimental program
Comparison scheme
Effect test

specific Embodiment approach 1

[0004] Specific embodiment 1: This embodiment is realized as follows: a. Place L-lactic acid on the auxiliary reaction medium, increase the vacuum degree of the system from 0.050~0.070MPa to 0.080~0.099MPa, and microwave radiation for 30~50min to obtain Prepolymer (OLLA) with a viscosity average molecular weight of 3000~5000; b. Add catalyst to the prepolymer and irradiate microwave for 2~5min under normal pressure; c. Then, the vacuum degree is 0.085~0.1Mpa and the microwave power is 500 Under the condition of ~550W, irradiate for 25-50min to obtain polylactic acid with a viscosity average molecular weight of 40,000 to 60,000. The auxiliary reaction medium is SiC; the catalyst is SnCl 2 And p-toluenesulfonic acid (TSA), of which SnCl 2 ·2H 2 O accounts for 0.3~0.50% of the weight of the prepolymer, p-toluenesulfonic acid and SnCl 2 ·2H 2 The molar ratio of O is 1: (0.5-2.0).

specific Embodiment approach 2

[0005] Specific embodiment two: This embodiment is realized as follows: a. Place L-lactic acid on the auxiliary reaction medium, increase the vacuum of the system from 0.06MPa to 0.095MPa, and microwave radiation for 40 minutes to obtain a viscosity average molecular weight of 4000 Prepolymer (OLLA); b. Add catalyst to the prepolymer and irradiate microwave for 3min under normal pressure; c. Then irradiate for 40min under the conditions of vacuum degree of 0.095Mpa and microwave power of 528W to obtain a viscosity average molecular weight of 50000 Of polylactic acid.

specific Embodiment approach 3

[0006] Specific embodiment three: This embodiment is realized as follows: a. Add 20ml of L-lactic acid with a weight concentration of 70-90% in a 150ml single-neck round bottom flask equipped with a stirrer, and place the reaction flask on the SiC auxiliary reaction medium. During the reaction, gradually increase the vacuum of the system from 0.05 to 0.07 MPa to 0.080 to 0.099 MPa, and use microwave radiation for 30 to 50 minutes to obtain a prepolymer (OLLA) with a viscosity average molecular weight of 3000-5000; b. Release the vacuum and move toward prepolymerization. Add SnCl 2 And TSA catalyst, in which SnCl 2 ·2H 2 O accounts for 0.35~0.50% of OLLA weight, p-toluenesulfonic acid (TSA) and SnCl 2 ·2H 2 The molar ratio of O is 1:(0.5~2.0), microwave irradiation is stirred and dissolved under normal pressure for 2~5min; c. Then, it is irradiated for 25~50min under the conditions of vacuum degree of 0.085~0.1Mpa and microwave power of 500~550W, A polylactic acid having a viscosit...

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Abstract

The invention discloses the synthesis of poly lactic acid by microwave radiation melt polycondensation method which comprises, (1) placing L-lactic acid on auxiliary reaction medium, increasing the system vacuum from 0.050-0.070 Mpa to 0.080-0.099Mpa, microwave radiating 30-50 min, obtaining prepolymer (OLLA), (2) charging catalyst into the prepolymer, microwave radiating 2-5 min under normal pressure, (3) under the condition of vacuum 0.085-0.1Mpa, microwave power 500-550W, radiating 25-50min, thus obtaining polylactic acid.

Description

Technical field: [0001] The present invention relates to a method for synthesizing polylactic acid. Background technique: [0002] Polylactic acid is a new type of polymer material. It has good biodegradability, biocompatibility and mechanical strength. It is an ideal biodegradable material. It is used in human tissue repair, wound suture, and controlled release of medicines and pesticides. It has broad application prospects; in some other fields, polylactic acid can replace traditional polymer materials, which can also reduce environmental pollution and harm. There are two main ways to synthesize polylactic acid: ring-opening polymerization method and direct polycondensation method. The ring-opening polymerization method requires high-purity lactide, which is usually prepared by recrystallization. This method has a long route and a complicated process, resulting in high price of polylactic acid, which is difficult to compete with general-purpose plastics. The direct polycondensa...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G63/06C08G63/78
Inventor 王鹏舒静田六一
Owner HARBIN INST OF TECH
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