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Method for preparing film poly-L-lactic acid copolymer by inner plasticizing

A lactic acid copolymerization and film-level technology, which is applied in the field of film-grade poly-L-lactic acid copolymer preparation, can solve the problems of complexity, lengthy refining process, high cost of polylactic acid, etc., and achieve the effect of low cost

Inactive Publication Date: 2005-03-16
HEFEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the synthesis and refining process of lactide is lengthy and complicated, which leads to high cost of polylactic acid synthesized from it. At present, it is mainly used in the medical field in China

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example Construction

[0013] 1. Preparation of L-lactic acid prepolymer: Dehydrate L-lactic acid at 100-150°C and 1000-2000Pa for 2-4 hours until its water content is 1-2wt%, add the weight of L-lactic acid after dehydration 0.01-1.0 wt% of the catalyst is reacted at 140-200° C. and 0.1-2000 Pa for 5-30 hours to obtain the L-lactic acid prepolymer.

[0014] If the obtained L-lactic acid prepolymer has an acid value no higher than 7mg KOH / g, directly enter the next step;

[0015] If the obtained L-lactic acid prepolymer has an acid value higher than 7mg KOH / g, it isothermally crystallized at 90-140°C for 2-20 hours, crushed, and then crushed at 120-160°C and 0.1-2000Pa Solid phase polymerization for 5 to 30 hours.

[0016] Preparation of hydroxyl-terminated L-lactic acid prepolymer: Dehydrate L-lactic acid at 100-150°C and 1000-2000Pa for 2-4 hours until its water content is 1-2wt%. Add 0.5-4wt% small molecular diol, add a catalyst with 0.01-1.0wt% weight of L-lactic acid after dehydration, and re...

Embodiment 1

[0024] Take 400g, 85wt% L-lactic acid in a 1000mL single-necked round-bottom flask, place the flask on a rotary evaporator, the rotating speed of the rotary evaporator is 100rpm / min, heat in an oil bath at 100°C, and dehydrate for 2-4 hours under the condition of 1000Pa. Hours, until the water content is 1-2wt%. Add 1.7g of stannous octoate catalyst, the temperature of the oil bath is raised to 180°C, the rotational speed of the rotary evaporator is still 100rpm / min, gradually reduce the pressure to 100Pa, react for 10 hours, and pour it into a stainless steel pan after the reaction.

[0025] The above prepolymer was placed in a drying oven, the temperature was raised to 110° C., and the prepolymer was allowed to crystallize isothermally for 10 hours and then pulverized. Then put it into a vacuum drying oven at 150° C., evacuate to 300 Pa, perform solid-phase polymerization for 15 hours, and set aside.

[0026] Weigh 30g of polyethylene glycol with an average molecular weight...

Embodiment 2

[0029] The dehydration method of L-lactic acid is the same as embodiment 1. Take 500g of dehydrated L-lactic acid and place it in a 1000mL single-necked round bottom flask, add 5g of 1,4-butanediol and 2.5g of stannous octoate, place the flask on a rotary evaporator, raise the temperature of the oil bath to 180°C, and gradually reduce the pressure to 100Pa, react for 10 hours, pour it into a stainless steel pan after the reaction, and pulverize to obtain a hydroxyl-terminated L-lactic acid prepolymer.

[0030] Weigh 25g of polytetrahydrofuran ether diol with an average molecular weight of 2000, add it to a 250mL three-necked flask with mechanical stirring, protect it with nitrogen, heat the oil bath to 70°C, add 4.2g of HDI dropwise, and react for 3 hours to obtain the isocyanate-blocked terminal polytetrahydrofuran.

[0031] Weigh 200g of hydroxyl-terminated L-lactic acid prepolymer and place it in a 500mL three-neck flask with mechanical stirring and nitrogen protection dev...

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Abstract

The invention discloses a method for preparing film poly-L-lactic acid copolymer by inner plasticizing which comprises the steps of, (1) using L-lactic acid as raw material, synthesizing L-lactic acid prepolymer or end hydroxy L-lactic acid prepolymer through method of direct melting polycondensation, (2) expanding chains for the L-lactic acid prepolymer or end hydroxy L-lactic acid prepolymer in step (1), so as to obtain reinforced thin film level poly-L-lactic acid copolymer.

Description

technical field [0001] The invention relates to a method for preparing film grade poly L-lactic acid copolymer by using L-lactic acid as raw material. Background technique: [0002] Plastics have been widely used in various fields of the national economy and people's daily life. At present, the annual total output of plastics in the world is still increasing at a rate of more than 5%. However, the development of plastics is facing two serious problems: one is that the environmental pollution caused by a large amount of waste plastics is becoming more and more serious; the other is that the petroleum resources that general-purpose plastics rely on are limited and increasingly scarce. [0003] Polylactic acid will be completely degraded to CO by microorganisms in an oxygen-rich and high-humidity environment 2 and H 2 O, its raw material lactic acid can be prepared by fermentation of starch, etc., which is an environmentally renewable resource, can avoid the shortage of oil r...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G63/02C08G63/78
Inventor 周正发徐卫兵左春荣
Owner HEFEI UNIV OF TECH
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