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Melt polycondensation method for preparing high molecular weight polylactic acid

A technology of melt polycondensation and high molecular weight, applied in the field of organic polymer materials, can solve the problems of high viscosity, difficult removal of by-product water, difficulty in obtaining high molecular weight polylactic acid, etc., and achieve high molecular weight, low cost and high yield Effect

Inactive Publication Date: 2010-06-16
江西省科院生物技术有限责任公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to overcome the problem of high viscosity of the reaction system in the existing polylactic acid melt polycondensation process, and the difficult removal of by-product water so that it is difficult to obtain high molecular weight polylactic acid. Lactic acid methods to meet production and application needs

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Add 100 g of L-lactic acid with a content of 90% into a three-necked flask with a stirring device, and install a condensing device. Raise the temperature to 150°C and react at normal pressure for 3 hours; depressurize to 13KPa and react for 2 hours; continue to depressurize to 4KPa and dehydrate for 2 hours; the prepolymer OLLA is obtained. Add the prepolymer into a 250ml three-neck flask with a stirring device, install the condensing device, add 0.1wt% SnCl 2 2H 2 O (relative to lactic acid mass) and p-toluenesulfonic acid (TSA) (with SnCl 2 2H 2 (2 molar ratio is 1: 1), and add 3.5wt% lactide (relative to lactic acid quality), depressurize to 300Pa, reaction temperature is set to 170 ℃, condensation temperature is set to 85 ℃, reacted for 12 hours, obtained 69g polylactic acid. The weight average molecular weight of polylactic acid measured by GPC method is 12,000.

Embodiment 2

[0027] Add 90 g of L-lactic acid with a content of 90% into a three-neck flask with a stirring device, and install a condensing device. Raise the temperature to 150°C and react at normal pressure for 3 hours; depressurize to 13KPa and react for 2 hours; continue to depressurize to 4KPa and dehydrate for 2 hours; the prepolymer OLLA is obtained. Add the prepolymer into a 250ml three-neck flask with a stirring device, install the condensing device, add 0.1wt% SnCl 2 2H 2 O (relative to lactic acid mass) and p-toluenesulfonic acid (TSA) (with SnCl 2 2H 2 (2 molar ratio is 1: 1), and add 3.5wt% lactide (relative to lactic acid quality), depressurize to 3000Pa, reaction temperature is set to 190 ℃, condensation temperature is set to 85 ℃, reacted for 20 hours, obtained 62g polylactic acid. The weight average molecular weight of polylactic acid measured by GPC method is 37,000.

Embodiment 3

[0029] Add 98g of L-lactic acid with a content of 90% into a three-necked flask with a stirring device, and install a condensing device. Raise the temperature to 150°C and react at normal pressure for 3 hours; depressurize to 13KPa and react for 2 hours; continue to depressurize to 4KPa and dehydrate for 2 hours; the prepolymer OLLA is obtained. Add the prepolymer into a 250ml three-neck flask with a stirring device, install the condensing device, add 0.35wt% SnCl 2 2H 2 O (relative to lactic acid mass) and p-toluenesulfonic acid (TSA) (with SnCl 2 2H 2 (2 molar ratio is 1: 1), and add the lactide of 1wt% (relative to lactic acid quality), depressurize to 3000Pa, reaction temperature is set as 180 ℃, condensation temperature is set as 85 ℃, reacts for 12 hours, obtains 67g polylactic acid. The weight average molecular weight of polylactic acid measured by GPC method is 17,000.

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PUM

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Abstract

The invention discloses a melt polycondensation method for preparing high molecular weight polylactic acid. The method is characterized by comprising the steps of: (1) pre-polymerizing, namely adopting a heating decompression dehydration process to remove free water and partial bound water in a raw material, namely lactic acid, to obtain a prepolymer, wherein the temperature of a reaction system is between 100 and 200 DEG C, and the pressure of the reaction system is between 0 and 30kPa; and 2) performing azeotropic water removal polycondensation by lactide, namely taking the prepolymer prepared in the step (1) as a raw material for polycondensation under the condition of adding a catalyst, a cocatalyst and an azeotropic water removal agent, namely the lactide, wherein the temperature of the reaction system is between 150 and 250 DEG C, the pressure of the reaction system is between 0 and 20kPa, the reaction time is between 1 and 45 hours, the adding amount of the catalyst is between 0.001 and 5 weight percent, the adding amount of the cocatalyst is between 0.001 and 5 weight percent, and the adding amount of the azeotropic water removal agent, namely the lactide is between 0.01 and 50 weight percent.

Description

technical field [0001] The invention belongs to the field of organic polymer materials, and relates to a preparation method of polylactic acid, in particular to a method for directly synthesizing high-molecular-weight polylactic acid by a melting polycondensation method. Background technique [0002] Polylactic acid (PLA) is a biodegradable polymer material produced from renewable resources such as corn starch. An ideal ecological cycle that participates in the process of regeneration of biomass resources is part of the natural carbon cycle. Polylactic acid is non-toxic and non-irritating, and is a typical green chemical. High molecular weight polylactic acid has a glass transition temperature of about 60°C and a melting point of 170-200°C. It is a thermoplastic polymer with similar physical and mechanical properties to polystyrene (PS) and polyester (PET), and has excellent properties. Physical and mechanical properties, and good processing performance, can be processed b...

Claims

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Application Information

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IPC IPC(8): C08G63/08C08G63/78
Inventor 唐颂超印培民王庆海蒲文亮侯文婷
Owner 江西省科院生物技术有限责任公司
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