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Process for preparing high molecular weight poly lactic acid by fusion polycondensation-solid phase polymerization

A technology of solid-phase polymerization and high molecular weight, applied in the field of preparation of polylactic acid, can solve problems such as low molecular weight, and achieve the effects of short process route, low cost and simple operation method.

Inactive Publication Date: 2005-05-18
SHANGHAI CHLOR ALKALI CHEM
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  • Summary
  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved in the present invention is to disclose a method for preparing high-molecular-weight polylactic acid by melt polycondensation-solid-state polymerization, so as to overcome the defects of low molecular weight in the prior art

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Weigh 400g 85% L-lactic acid (Purac company product) 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 gradually decompress until no water droplets are formed.

[0020] Fill with nitrogen to relieve the pressure, add stannous octoate catalyst with 0.5% weight of L-lactic acid after dehydration, the temperature of the oil bath is raised to 180°C, the rotating speed of the rotary evaporator is still 100rpm / min, gradually reduce the pressure to 100Pa, react for 10h, and the reaction ends Pour into a stainless steel pan.

[0021] Put the above prepolymer in a vacuum drying oven, vacuumize, fill with nitrogen to release the pressure, raise the temperature to 110°C, allow the prepolymer to crystallize isothermally for 10 hours, and then pulverize. Take 200g of isothermally crystallized and pulverized prepolymer and place it in a stainless steel tra...

Embodiment 2

[0023] Adopt the method identical with embodiment 1, the preparation of L-lactic acid prepolymer, and the condition of solid phase polymerization are the same as embodiment 1, replace the 5A molecular sieve in embodiment 1 with 3A molecular sieve, the Mw of polylactic acid recorded by GPC method is 126,000.

Embodiment 3

[0025] Using the same method as in Example 1, replacing stannous octoate with stannous chloride, the Mw of the polylactic acid obtained was 110,000.

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Abstract

The fusion polycondensation and solid phase polymerization process for preparing high molecular weight polylactic acid includes: the fusion polycondensation step of decompression dewatering material L-lactic acid gradually and adding catalyst for polycondensation; and the solid phase polymerization step of constant temperature crystallizing the pre-polymer, crushing and adding molecular sieve for solid phase polymerization. The process of the present invention has short technological path, simple operation, low cost and high molecular weight of polylactic acid product.

Description

technical field [0001] The invention relates to a method for preparing polylactic acid, in particular to a method for preparing high molecular weight polylactic acid. Background technique [0002] Plastics have been widely used in various fields of national economy and people's daily life. At present, the total annual output of plastics in the world is about 150 million tons, and it is increasing at a rate of more than 5%. However, the development of plastics is facing two serious problems; one is the limited raw materials, which are increasingly in short supply; the other is serious environmental pollution. Most of the resin raw materials used in plastic products come from petrochemicals. While vigorously developing petrochemical products, people also found that Shishan resources are limited. Due to its own and external effects and influences, plastic materials will gradually age and become waste, becoming a huge source of pollution for society. [0003] Polylactic acid ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08G63/02C08G63/80C08G63/85
Inventor 邢云杰袁茂全
Owner SHANGHAI CHLOR ALKALI CHEM
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