Method for preparing high-molecular-weight polylactic acid through direct condensation polymerization

A high-molecular-weight, polylactic acid technology, applied in the field of preparing high-molecular-weight polylactic acid, can solve the problems of high polylactic acid material price, high equipment requirements, complex process, etc., and achieve the effects of accelerating the lactic acid polycondensation reaction, low equipment requirements, and simple process.

Inactive Publication Date: 2013-06-26
SHAANXI UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although the above method can obtain high-molecular-weight polylactic acid, there are disadvantages such as high equipment requirements, high energy consumption, and complicated processes, which make the price of polylactic acid materials relatively high, and the wide application of its products is limited.

Method used

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  • Method for preparing high-molecular-weight polylactic acid through direct condensation polymerization

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] 1) Mix 35g of lactic acid aqueous solution with a mass concentration of 85-90% (Tianjin Kemiou Chemical Reagent Co., Ltd.) and 10mL of toluene, and then rotate and dehydrate under reduced pressure at 65°C and a vacuum of 0.085MPa for 1h, that is Dehydrated lactic acid;

[0025] 2) Add dehydrated lactic acid into a 250mL three-neck flask, stir and raise the temperature to 100°C, then keep it warm for 10min under a vacuum of 0.065MPa, then drop the mixed solution of stannous octoate within 0.5h, keep it warm for 30min, stir and raise the temperature Temperature to 170°C and heat preservation for 5 hours under a vacuum of 0.095MPa to obtain a crude product, then purify, filter and dry the crude product to obtain a high molecular weight polylactic acid with a molecular weight of 60,000;

[0026] Among them, the mass of stannous octoate in the mixed solution of stannous octoate is 0.5% of the mass of dehydrated lactic acid, and the mixed solution of stannous octoate is compo...

Embodiment 2

[0028] 1) Mix 35g of lactic acid aqueous solution with a mass concentration of 85-90% (Tianjin Kemiou Chemical Reagent Co., Ltd.) and 10mL of toluene, and then rotate and dehydrate under reduced pressure at 65°C and a vacuum of 0.085MPa for 1h, that is Dehydrated lactic acid;

[0029] 2) Add dehydrated lactic acid into a 250mL three-necked flask, stir and raise the temperature to 90°C, keep it warm for 10min under a vacuum of 0.065MPa, then drop the mixed solution of stannous octoate within 0.5h, then keep it warm for 30min, stir and raise the temperature To 180°C and keep it under a vacuum of 0.095MPa for 5 hours to obtain a crude product, then purify, filter and dry the crude product to obtain a high molecular weight polylactic acid with a molecular weight of 80,000;

[0030] Among them, the mass of stannous octoate in the mixed solution of stannous octoate is 0.5% of the mass of dehydrated lactic acid, and the mixed solution of stannous octoate is composed of 0.15 g of stan...

Embodiment 3

[0033] 1) Mix 35g of lactic acid aqueous solution with a mass concentration of 85-90% (Tianjin Kemiou Chemical Reagent Co., Ltd.) and 10mL of toluene, and then rotate and dehydrate under reduced pressure at 65°C and a vacuum of 0.085MPa for 1h, that is Dehydrated lactic acid;

[0034] 2) Add dehydrated lactic acid into a 250mL three-necked flask, stir and heat up to 100°C, keep warm for 10min under a vacuum of 0.065MPa, then drop the mixed solution of stannous octoate within 0.5h, then keep warm for 30min, stir and heat up Heat at 190°C and keep it under a vacuum of 0.095MPa for 5 hours to obtain a crude product, then purify, filter and dry the crude product to obtain a high molecular weight polylactic acid with a molecular weight of 100,000;

[0035] Among them, the mass of stannous octoate in the mixed solution of stannous octoate is 0.5% of the mass of dehydrated lactic acid, and the mixed solution of stannous octoate is composed of 0.15 g of stannous octoate and 20 mL of t...

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Abstract

The invention provides a method for preparing high-molecular-weight polylactic acid through direct condensation polymerization, which comprises the following steps of: stirring and heating dehydrated lactic acid to 90-120 DEG C; carrying out heat preservation for 10-30 minutes at a vacuum degree of 0.060-0.065MPa; dropwise adding the mixed solution of a tin catalyst, and carrying out heat preservation and reacting for 10-30 minutes; heating to 160-200 DEG C, and carrying out heat preservation and reacting for 4-9 hours at a vacuum degree of 0.065-0.095MPa to obtain a crude product; and purifying, filtering and drying the crude product to obtain high-molecular-weight polylactic acid. According to the invention, the tin catalyst is dispersed in an organic solvent and dropwise added into the reaction system, the inactivation of the tin catalyst can be effectively prevented, the condensation polymerization reaction of lactic acid can be uniformly accelerated, and the reaction time is shortened; and moreover, the reaction byproduct can be discharged out of the reaction system along with the organic solvent in the mixed solution of the tin catalyst at low vacuum degree so that the reaction goes rightward and the reaction speed is increased.

Description

technical field [0001] The invention relates to a method for preparing high-molecular-weight polylactic acid, in particular to a method for preparing high-molecular-weight polylactic acid by direct polycondensation. Background technique [0002] In recent years, environmental friendly materials have been paid attention to. Lactic acid can be obtained by fermenting crop straw or its fruit (such as corn, etc.) as a raw material, and polylactic acid, a biodegradable material with high molecular weight, can be obtained through condensation polymerization of lactic acid. This polylactic acid material can be biodegraded by microorganisms in a short period of time to generate water and carbon dioxide, and will not cause white pollution to the environment. It is a green plastic material. Polylactic acid materials have been used in medical fields, packaging fields, etc. [0003] At present, domestic reports on the preparation of polylactic acid include: Zhou Xinggui et al.’s invent...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G63/06C08G63/78C08G63/85
Inventor 樊国栋黎永利张昭崔梦雅
Owner SHAANXI UNIV OF SCI & TECH
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