Method for synthesizing high molecular weight polylactic acid

A technology of high molecular weight and polylactic acid, applied in the field of synthesis of organic polymer compounds, can solve problems such as low production efficiency and long reaction time

Inactive Publication Date: 2010-06-23
BEIJING INSTITUTE OF CLOTHING TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The solid-state polycondensation method has a l

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] In the 250mL reaction bottle, add L-lactic acid and polylactic acid (viscosity-average molecular weight is 3,000) altogether 120 grams, the two mass ratios are 3: 7, and the catalyst stannous chloride of 0.5% (W / W), at 104 Distill under reduced pressure at ~110°C for 2 hours to remove moisture in L-lactic acid, and keep the absolute pressure at 1kPa. Then the temperature was raised to 160-180° C., the absolute pressure was reduced to 70 Pa, and the reaction was carried out under stirring for 10 hours to obtain the product polylactic acid, whose viscosity-average molecular weight was measured to be 17,600.

Embodiment 2

[0017] In a 250mL reaction bottle, add a total of 100 grams of dehydrated L-lactic acid and polylactic acid (viscosity average molecular weight: 6,000), the mass ratio of the two is 5:5, and add 0.5% (W / W) catalyst chlorinated chlorinated acid. Tin, heated to 160-180°C, stirred and reacted for 10 hours under an absolute pressure of 70 Pa to obtain polylactic acid, and its viscosity-average molecular weight was measured to be 22,600.

Embodiment 3

[0019] In a 250mL reaction bottle, add 36 grams of polylactic acid (viscosity-average molecular weight: 8,500), raise the temperature to 160-180°C, keep an absolute pressure below 70Pa, and continuously add 80 grams of dehydrated L-lactic acid ( Containing 0.5% (W / W) of the catalyst stannous chloride), the dripping time is 4 hours, and the total reaction time is 10 hours to obtain the product polylactic acid, and the viscosity-average molecular weight is 42,600.

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Abstract

The invention relates to a novel method for preparing high molecular weight polylactic acid through direct-melting polycondensation. The method has the key that a certain amount of low molecular weight polylactic acid serving as base material is added to a reaction system for participating in the polycondensation of lactic acid, and the addition of the base material can reduce the concentration of the lactic acid in the system so as to reduce the ring formation probability in the polycondensation of lactic acid, promote the proceeding of polycondensation, raise polymerization rate, greatly increase the molecular weight of polylactic acid products and overcome the disadvantages that the direct polycondensation method of lactic acid is long in reaction time, low in molecular weight of products and the like. Change in the polymerization process ensures simple process of lactic acid polymerization, single product structure and high molecular weight.

Description

technical field [0001] The invention relates to a method for synthesizing organic macromolecular compounds, in particular to a new method for preparing high-molecular-weight polylactic acid through direct condensation of lactic acid. Background technique [0002] At present, countries all over the world are devoting themselves to the research of biological / environmentally degradable materials. Among the degradable polymer materials found so far, aliphatic polyester is the most attractive. Under natural conditions, they can be completely degraded into substances that exist in the natural ecological cycle: water and carbon dioxide. Polylactic acid (PLA) in aliphatic polyester is a completely degradable and environmentally friendly material prepared from lactic acid obtained from starch fermentation as a basic raw material. It not only has excellent performance comparable to engineering plastics, but also recovers lactic acid monomers by physical or chemical methods after use...

Claims

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Application Information

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IPC IPC(8): C08G63/78C08G63/06
Inventor 张天骄吕延松罗莎
Owner BEIJING INSTITUTE OF CLOTHING TECHNOLOGY
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