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A kind of preparation method of high molecular weight polylactic acid

A high-molecular-weight, polylactic acid technology, applied in the field of preparation of high-molecular-weight polylactic acid, can solve the problems of high preparation cost, difficult reaction, poor mechanical properties of polylactic acid, etc., and achieve the effects of improving mechanical properties and increasing molecular weight

Active Publication Date: 2021-10-26
上海汉禾生物新材料科技有限公司 +1
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Problems solved by technology

[0006] In order to overcome the defects of low molecular weight of polylactic acid, poor mechanical properties of polylactic acid, difficult reaction and high production cost in the prior art, the present invention provides a polylactic acid and a preparation method thereof, so as to increase the molecular weight of polylactic acid and realize the synthesis of polylactic acid. molecular regulation

Method used

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  • A kind of preparation method of high molecular weight polylactic acid

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Effect test

Embodiment 1

[0031] Prepolymerization: Raise the temperature in the reactor containing 100 parts of lactic acid and 5 parts of activated clay to 95°C, adjust the vacuum degree to 8KPa, dehydrate for 2 hours, and then raise it to 140°C, adjust the vacuum degree in the reactor to 7KPa, dehydration reaction 3h, the prepolymer was obtained.

[0032] Polymerization: Add 0.5 part of dibutyltin dichloride to the prepolymer obtained in the prepolymerization step, and stir and melt polymerize for 5 hours at a temperature of 150° C. and a vacuum of 5 KPa to obtain the first polymer.

[0033] The total amount of bisoxazoline chain extenders and polycarboxy compounds used in this example is 0.2% of the weight of lactic acid, and the weight ratio of bisoxazoline chain extenders and polycarboxy compounds is 5:1.

[0034] Chain extension: Add chain extender 2,2'-(1,3-phenylene)bisoxazoline to the first polymer obtained in the polymerization step, and stir the reaction at a temperature of 160°C and a vacu...

Embodiment 2

[0037] The rest is the same as in Example 1, except that the weight ratio of the chain extender 2,2'-(1,3-phenylene)bisoxazoline to the crosslinking agent citric acid is 10:1.

Embodiment 3

[0039] The rest is the same as in Example 1, except that the weight ratio of the chain extender 2,2'-(1,3-phenylene)bisoxazoline to the crosslinking agent citric acid is 15:1.

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Abstract

The invention provides a method for preparing high-molecular-weight polylactic acid. The preparation method of polylactic acid includes the steps of: prepolymerization, polymerization, chain extension, and crosslinking. The chain extender in the crosslinking step is a bisoxazoline chain extender. agent, and in the crosslinking step, the crosslinking agent is a polycarboxy compound. The present invention uses polycarboxy compounds to make polylactic acid molecules react to form a network crosslinked structure, further increases the molecular weight of polylactic acid, improves the mechanical properties of polylactic acid, and unexpectedly finds that the bisoxazoline chain extension used There is a synergistic effect between the agent and the polycarboxy compound added in the crosslinking step. Adjusting the ratio of the two can not only increase the molecular weight of polylactic acid, but also the color of the product is not affected by chain extension and crosslinking. The present invention also finds that adding activated clay in the prepolymerization step can not only improve the impact resistance of polylactic acid, but also reduce the difficulty of reaction and further increase the weight average molecular weight of polylactic acid.

Description

technical field [0001] The invention relates to the technical field of polymer materials, in particular to a preparation method of high molecular weight polylactic acid. Background technique [0002] Polylactic acid is the bioplastic with the most application potential. It has the advantages of reliable biosafety, biodegradability, environmental friendliness, good mechanical properties and easy processing. It is used in medical polymer materials, 3D printing, textiles, agriculture, etc. It is one of the effective ways to solve "white pollution" and has huge ecological benefits. [0003] Polylactic acid is a high-molecular polymer produced by polymerization of single-molecule lactic acid. At present, the raw materials for producing lactic acid come from grains. The production cost of using such lactic acid is high, and the produced plastic products cannot compete with petrochemical plastics in market price, making The application of polylactic acid is still limited to high-e...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08G63/08C08G63/91C08K7/26C08J3/24C08L67/04
CPCC08G63/08C08G63/912C08J3/24C08J2367/04C08K7/26
Inventor 武瑛方品文程剑飞刘畅
Owner 上海汉禾生物新材料科技有限公司
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