Direct fusion method for preparing poly lactic acid in high molecular weight

A high-molecular-weight polylactic acid technology, which is applied in the field of direct melting to prepare high-molecular-weight polylactic acid, can solve problems such as high cost polycondensation, inability to fully achieve the effect, and impure products

Active Publication Date: 2005-01-12
马鞍山同杰良生物材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Japanese patent JP62-1017 uses 2-oxazoline as a chain extender, and the intrinsic viscosity of polylactic acid is improved to a certain extent; in patent CN1446836, polyhydric alcohols and polyacids are used as chain extenders to prepare highly branched polylactic acid. The molecular weight has been greatly improved, but organic solvents are used in the preparation process, the product is impure and the cost is higher than that of direct melt polycondensation
Therefore, there are still many deficiencies in these chain extension methods and chain extenders, which cannot fully achieve satisfactory results.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Add 50ml of L-lactic acid with a content of 85% to a 250ml four-necked bottle equipped with a thermometer, a stirrer and a nitrogen inlet tube, feed nitrogen, heat to 110°C, and stir and dehydrate for 2 hours under a vacuum of 80mmHg; then , add 0.2 grams of stannous chloride, gradually increase the temperature from 110°C to 160°C, and polycondense for 10 hours under a vacuum of 10mmHg to obtain a lactic acid polymer with an intrinsic viscosity of 0.15dl / g; finally, add 1wt% (relative to the quality of lactic acid) 1,2 epoxy octanoyl chloride, reacted for 3 hours to obtain polylactic acid with an intrinsic viscosity of 1.1dl / g.

Embodiment 2～6

[0026] Based on Example 1, the chain extender is 1,2 epoxy octanoyl chloride, change the consumption of adding chain extender, obtain the following results:

[0027] The amount of chain extender (relative to the quality of lactic acid) Intrinsic viscosity of polylactic acid

[0028] 0.5wt% 0.8dl / g

[0029] 2wt% 1.4dl / g

[0030] 4wt% 1.1dl / g

[0031] 6wt% 0.65dl / g

[0032] 10wt% 0.4dl / g

Embodiment 8

[0034] Based on Example 1, first polymerize to obtain a lactic acid polymer with an intrinsic viscosity of 0.15dl / g, and then prepare high-molecular-weight polylactic acid by reactive extrusion, and the obtained polylactic acid has an intrinsic viscosity of 1.3dl / g. During the reactive extrusion process, 2 wt % (relative to the mass of lactic acid) of 1,2 epoxy octanoyl chloride was added, the vacuum degree was 50 mmHg, and the reactive extrusion was carried out under the condition of nitrogen flow, and the residence time in the extruder was 10 minutes.

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PUM

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Abstract

In the method, prepolymer of polylactic is obtained by direct melt polycondensation, then chain extender containing two active functional groups in which one is easy to react with hydroxyl and another is easy to react with carboxy is added. The viscosity of polylactic prepared by the chain extendor can be increased up to 1.0-1.5 dl/g.

Description

technical field [0001] The invention belongs to the technical field of polymer materials, and in particular relates to a method for directly melting and preparing high-molecular-weight polylactic acid. Background technique [0002] Lactic acid widely exists in nature, not only harmless to organisms, but also an important component of organisms. The polylactic acid obtained by the polymerization of lactic acid is easily hydrolyzed into harmless small molecules in the presence of water, and can also decompose itself under natural conditions. Therefore, polylactic acid has been widely studied and applied as a general material. [0003] High molecular weight polylactic acid is usually obtained by ring-opening polymerization of lactide (a cyclic dimer of lactic acid). In the patent U.S. Patent No. 2,758,987, L-lactide is first prepared from L-lactic acid, and then polylactic acid is obtained by ring-opening polymerization. Although the polylactic acid prepared by this method h...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G63/06C08G63/80
Inventor 任杰王秦峰张乃文
Owner 马鞍山同杰良生物材料有限公司
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