A kind of preparation method of polylactic acid with low optical purity and high molecular weight

A technology of polylactic acid and monohydric alcohol, which is applied in the field of polymer synthesis and preparation, can solve the problems of high price and uneconomical, and achieve the effects of easy operation, low optical purity and simple process route

Active Publication Date: 2016-09-28
普立思生物科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, it is easy to obtain L-lactide and D-lactide in the industry, but because the preparation of D-lactide needs to use scarce D-lactic acid, which makes it expensive, it can be seen that the above method is not economical.

Method used

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Examples

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preparation example Construction

[0021] The invention provides a kind of preparation method of low optical purity high molecular weight polylactic acid, comprising the following steps:

[0022] The lactide is subjected to isomerization reaction under the catalysis of alcohol alkali metal salt, the optical purity of L-lactide or D-lactide in the lactide is 90% to 100%, and meso- Isomer mixtures of lactide, D-lactide and L-lactide;

[0023] The isomer mixture is polymerized to obtain polylactic acid with low optical purity and high molecular weight.

[0024] In the present invention, lactide is subjected to isomerization reaction under the catalysis of alcohol alkali metal salts, the optical purity of L-lactide or D-lactide in the lactide is 90% to 100%, and the obtained meso - a mixture of isomers of lactide, D-lactide and L-lactide.

[0025] In the present invention, the lactide includes L-lactide and D-lactide; the optical purity of L-lactide or D-lactide in the lactide is 90%-100%. The present invention ...

Embodiment 1

[0048] The three-neck flask (1000 mL) equipped with a magnetic stirrer and a thermometer was strictly dried, and the air in the three-neck flask was replaced with high-purity nitrogen gas for 3 to 5 times under high vacuum conditions, and 144.2 g of L-lactide ( Optical purity >99.5%, purchased from PURAC company), replaced with high-purity nitrogen for 3 times, added 0.036g of potassium methoxide under the protection of high-purity nitrogen, heated, and after the lactide melted, started stirring and raised the temperature to 180°C. Control the temperature at 180-185°C, keep it for 50 minutes, and cool to 140-160°C to obtain the isomer mixture of meso-lactide, D-lactide and L-lactide;

[0049] Under the conditions of vacuum degree of -0.095~-0.1MPa and temperature of 125~140℃, the isomer mixture of lactide is distilled under reduced pressure, and the distilled lactide fraction is collected. When the liquid in the three-necked bottle remains When the amount is about 1 / 4 to 1 / 3 o...

Embodiment 2

[0053] The three-neck flask (1000 mL) equipped with a magnetic stirrer and a thermometer was strictly dried, and the air in the three-neck flask was replaced with high-purity nitrogen gas for 3 to 5 times under high vacuum conditions, and 151.00 g of L-lactide was added ( Optical purity>99.5%, purchased from PURAC company), replaced with high-purity nitrogen for 3 times, added 0.040g of potassium methoxide under the protection of high-purity nitrogen, heated, and after the lactide melted, started stirring and raised the temperature to 195°C. Control the temperature at 195-200°C, keep it for 50 minutes, and cool to 140-160°C to obtain the isomer mixture of meso-lactide, D-lactide and L-lactide;

[0054] Under the condition of vacuum degree of -0.095~-0.1MPa and temperature of 125~140℃, the isomer mixture of lactide is distilled under reduced pressure, and the distilled lactide fractions are collected and used as the liquid in the three-necked flask When the remaining amount is ...

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Abstract

The invention provides a preparation method of polylactic acid with low optical purity and high molecular weight. The method comprises the following steps: enabling lactide, to be subjected to isomerization reaction under the catalysis of alcohol alkali metal salt, so as to obtain isomer mixture of meso-lactide, D-lactide and L-lactide, wherein the optical purity of L-lactide or D-lactide in lactide is 90 to 100 percent; enabling the mixture to be subjected to polymerization reaction, so as to obtain the polylactic acid with low optical purity and high molecular weight. The preparation method is simple in process route and easy to operate; the polylactic acid prepared is low in optical purity. The weight-average molecular weight of the polylactic acid prepared through the preparation method is 90 to 120 kg / mol, the molecular weight distribution index is 1.3 to 1.7, the glass-transition temperature is 53 to 57 DEG C, and the optical rotation is -125 to 120 degrees.

Description

technical field [0001] The invention relates to the field of polymer synthesis and preparation, in particular to a method for preparing polylactic acid with low optical purity and high molecular weight. Background technique [0002] Polylactic acid (PLA) is a new type of polymer material that is completely biodegradable. It has good biocompatibility and biodegradability. It can be decomposed into carbon dioxide and water in the body and in the natural environment. Poison is harmless. With the strengthening of people's awareness of environmental protection, more and more people pay more attention to PLA, and its application fields are expanding day by day. [0003] The degree of polymerization of high molecular weight polylactic acid is usually ≥ 1000 (calculated by lactoyl units). Polylactic acid includes poly-L-lactic acid (PLLA) and poly-D-lactic acid (PDLA). Polylactic acid is often due to a small amount of meso-lactide and / or D-lactide contained in the monomer L-lacti...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G63/08C08G63/85
Inventor 冯立栋边新超张瑜李杲陈学思
Owner 普立思生物科技有限公司
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