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Prepn of high molecular weight polylactic acid

A high molecular weight, polylactic acid technology, applied in the field of polylactic acid preparation, can solve the problems of high cost, complicated operation, and environmental pollution, and achieve the effect of low cost and simple equipment

Inactive Publication Date: 2007-01-03
DONGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The biggest disadvantage of this method is that it needs to prepare lactide of polymerization grade purity, the process is complex and the cost is relatively high
H.Ajioka et al reported in Bull.Chem.Soc.Jpn.1995,68:2125 that the polylactic acid of high molecular weight was obtained by solution polymerization direct method, but due to the need to use high boiling point solvent azeotrope, the operation is more complicated and the condition control is more complex. The most strict, the solvent is not easy to remove when the polymer is purified and there is a problem of solvent recovery
Moon S I et al reported in Polym SciA: Polym Chem2000, 38: 1673 ~ 1679 by direct melt polycondensation of lactic acid, using protonic acid-activated divalent tin compounds as catalysts to obtain high molecular weight polylactic acid (Mw=100000), and no Severe racemization and color change, but the use of a large amount of strong protonic acid will seriously pollute the environment and corrode equipment, and the strong acid in the product is not easy to remove

Method used

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Examples

Experimental program
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Effect test

Embodiment 1

[0017] Add L-lactic acid with a concentration of 90% into a three-necked flask with a stirring device, slowly heat to 100°C, depressurize to 1000Pa, stir and dehydrate for 3 hours; then remove the vacuum, and raise the temperature to 160°C in a nitrogen atmosphere , add L-lactic acid weight 1wt% stannous chloride as a catalyst, react for 7 hours; then gradually reduce the pressure to 200Pa within 7 hours, continue to react for 30 hours. figure 1 For the nuclear magnetic resonance spectrum of the polylactic acid prepared in this embodiment, figure 2 Its infrared spectrum. The spectrogram proves the structure of the synthesized polylactic acid, and the weight average molecular weight of the polylactic acid obtained by the viscosity method is 116,000.

Embodiment 2

[0019] Add L-lactic acid with a concentration of 90% into a three-necked flask with a stirring device, slowly heat to 150°C, depressurize to 10,000Pa, stir and dehydrate for 15 hours; then remove the vacuum, and raise the temperature to 220°C in a nitrogen atmosphere , add tetrabutyl titanate with 4wt% L-lactic acid weight as a catalyst, and react for 1 hour; then gradually reduce the pressure to 1000 Pa within 50 hours, and continue the reaction for 30 hours. The weight-average molecular weight of polylactic acid obtained by viscometry is 91,000.

Embodiment 3

[0021] Add L-lactic acid with a concentration of 90% into a three-necked flask with a stirring device, slowly heat to 70°C, depressurize to 300Pa, stir and dehydrate for 1 hour; then remove the vacuum, and raise the temperature to 100°C in a nitrogen atmosphere , adding tetrabutyl titanate with 5wt% L-lactic acid weight as a catalyst, and reacting for 50 hours; then gradually reducing the pressure to 10 Pa within 1 hour, and continuing the reaction for 40 hours. The weight-average molecular weight of polylactic acid obtained by viscometry is 120,000.

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Abstract

The preparation process of high molecular weight polylactic acid includes the following steps: 1. decompression reflux evaporation to eliminate water from lactic acid material; 2. esterifying the dewatered lactic acid in inert gas atmosphere; 3. pre-condensating the esterified product in the presence of catalyst through gradual decompression; and 4. low vacuum polycondensing the pre-polymer through gradual decompression and in the presence of catalyst to obtain high molecular weight polylactic acid. The present invention adopts direct smelting polycondensation, and has simple production process, simple production apparatus, low cost and easy realization in industrial production.

Description

technical field [0001] The invention relates to a preparation method of an organic polymer material, in particular to a preparation method of high molecular weight polylactic acid. Background technique [0002] Polylactic acid is a renewable biodegradable material with good biocompatibility. Because of its non-toxic, degradable, renewable and other characteristics, it meets the requirements of environmental protection and sustainable development, so it has attracted more and more attention from material researchers and business people. High molecular weight polylactic acid has a glass transition temperature of about 60°C and a melting point of about 180°C. It is a thermoplastic polymer with similar physical and mechanical properties to polystyrene (PS) and polyester (PET), and its processing performance is good. , can be extruded, injected, and blow-molded using general-purpose plastic processing equipment, and can also be blended or copolymerized with general-purpose plast...

Claims

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Application Information

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IPC IPC(8): C08G63/08C08G63/78C08G63/85
Inventor 余木火马海艳滕翠青韩克青
Owner DONGHUA UNIV
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