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Method for preparing polylactic acid material, and apparatus thereof

A technology of polylactic acid and lactic acid, which is applied in the field of devices for producing degradable biomaterials, and can solve problems such as poor heat resistance and hindering stereocomplexes

Inactive Publication Date: 2013-08-14
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When high molecular weight polylactic acid is used for melt blending, homopolylactic acid is easy to crystallize by itself, which hinders the formation of stereocomplexes. The polymer has two melting peaks and poor heat resistance

Method used

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  • Method for preparing polylactic acid material, and apparatus thereof
  • Method for preparing polylactic acid material, and apparatus thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] Add 15kg of D-lactide into a polymerization kettle with a capacity of 40L, remove the air in the kettle and fill it with nitrogen. Tin, stir evenly and heat up to 180°C, then polymerize at 0.1Mpa for 4 hours, the number-average molecular weight of D-polylactic acid is about 40,000, and then reduce the pressure in the polymerization system to remove lactide, the polymerization system The pressure inside is 20kPa. After removal, the residual amount of D-lactide monomer is 0.08%, and then the D-polylactic acid and the melted L monomer are mixed according to the mass ratio of 20 / 80 and then enter the tubular reactor. The residence time is 3h. The obtained polymer is a PLLA-b-PDLA diblock copolymer, and the obtained copolymer is subjected to a differential calorimetry scanning test, and a melting peak appears at 214°C.

Embodiment 2

[0039] Add 15kg of D-lactide into a polymerization kettle with a capacity of 40L, remove the air in the kettle and fill it with nitrogen. Tin, stir evenly and heat up to 180°C, then polymerize at 0.1Mpa for 4 hours, the number-average molecular weight of D-polylactic acid is about 40,000, and then reduce the pressure in the polymerization system to remove lactide, the polymerization system The pressure inside is 20kPa. After removal, the residual amount of D-lactide monomer is 0.09%, and then the D-polylactic acid and the molten L monomer are mixed according to the mass ratio of 40 / 60 and then enter the tubular reactor, and the material is in the tubular reactor The residence time is 3h. The obtained polymer is a PLLA-b-PDLA diblock copolymer, and the obtained copolymer is subjected to a differential calorimetry scanning test, and a melting peak appears at 216°C.

Embodiment 3

[0041] Add 15kg of D-lactide into a polymerization kettle with a volume of 40L, remove the air in the kettle and fill it with nitrogen, vacuumize and fill it with nitrogen several times, then raise the temperature to 120°C, and add 18g of octanoic acid after the D-lactide is completely melted Stannous, stir evenly and heat up to 180°C, then polymerize at 0.1Mpa for 4 hours, the number-average molecular weight of D-polylactic acid is about 40,000, and then reduce the pressure in the polymerization system to remove lactide, polymerize The pressure in the system is 20kPa. After removal, the residual amount of D-lactide monomer is 0.07%, and then the D-polylactic acid and the melted L monomer are mixed according to the mass ratio of 60 / 40 and then enter the tubular reactor. The residence time is 3h. The obtained polymer is a PLLA-b-PDLA diblock copolymer, and the obtained copolymer is subjected to a differential calorimetry scanning test, and a melting peak appears at 218°C.

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Abstract

The invention discloses a method for preparing polylactic acid only having stereocomplex crystallization, and an apparatus thereof. The method comprises the following steps: 1, carrying out ring opening polymerization of first lactide including lactic acid units having a same chirality under the action of a catalyst in an inert atmosphere to obtain homopolymerized polylactic acid having a number-average molecular weight of 4000-50000; 2, removing unreacted first lactide from the homopolymerized polylactic acid in a self-molten state under a reduced pressure to obtain purified homopolymerized polylactic acid; 3, pre-melting second lactide different from the first lactide in chiralities in the inert atmosphere; and 4, mixing the purified homopolymerized polylactic acid with molten second lactide monomers in the inert atmosphere according to a weight ratio of 96:4-4:96, and initiating polymerization of the second lactide monomers by treating the purified homopolymerized polylactic acid as a macromolecular initiator to obtain a PLLA-b-PDLA diblock copolymer. The PLLA-b-PDLA diblock copolymer is the polylactic acid only having isotactic complex crystallization, the weight ratio of L-polylactic acid to D-polylactic acid is 96:4-4:96, and the melting point of the PLLA-b-PDLA diblock copolymer is 180-230DEG C.

Description

technical field [0001] The invention relates to a device and method for producing degradable biomaterials, in particular to a method and device for producing polylactic acid containing only stereocomplex crystals. Background technique [0002] Polylactic acid (PLA) is a biodegradable polymer material produced from biomass resources formed through photosynthesis as the main starting material. After use, it can be degraded into lactic acid by microorganisms and finally decomposed into carbon dioxide and water. The synthesis and application of polylactic acid is actually an ideal ecological cycle that comes from renewable resources, and the degradation products return to nature after the end of service life, and participate in the regeneration of material resources. It belongs to the carbon cycle of nature. Polylactic acid is non-toxic, non-irritating, has excellent biocompatibility, bioabsorption, biodegradability, and also has excellent physical and mechanical properties, so ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G63/08C08G63/78
Inventor 杜影唐伟刚张月红刘铭闫岩孟伟娟齐可非张欣
Owner CHINA PETROLEUM & CHEM CORP