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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 production cost, difficult reaction, poor mechanical properties of polylactic acid, etc., and achieve the effect of improving mechanical properties and increasing molecular weight

Active Publication Date: 2020-01-14
上海汉禾生物新材料科技有限公司 +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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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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  • 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 preparation method of high-molecular-weight polylactic acid. The method comprises the following steps: prepolymerization, polymerization, chain extension and crosslinking, wherein a chain extender in the crosslinking step is a dioxazoline chain extender, and a crosslinking agent in the crosslinking step is a polycarboxyl compound. According to the invention, the polycarboxyl compound is used for enabling polylactic acid molecules to react so as to form a net-shaped cross-linked structure, so the molecular weight of polylactic acid is further increased, and the mechanical properties of polylactic acid are improved; meanwhile, it is unexpectedly found that a synergistic effect exists between the used dioxazoline chain extender and the polycarboxyl compound added in the crosslinking step, the molecular weight of the polylactic acid can be increased by adjusting the proportion of the dioxazoline chain extender to the polycarboxyl compound, and the color and lusterof the produced polylactic acid are not affected by chain extension and crosslinking.; moreover, activated clay added in the pre-polymerization step is found to have effect on improving the impact resistance of the polylactic acid, reducing reaction difficulty and further improving the weight-average molecular weight of the 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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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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