Synthesis of polylactate in supercrilical fluid of CO2
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A polylactic acid and supercritical technology, applied in the production of bulk chemicals, can solve the problems of heavy secondary pollution, high polymerization temperature and large side reactions, and achieve the effect of saving resources
Inactive Publication Date: 2005-02-23
DONGHUA UNIV
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[0007] The problem to be solved by the present invention is to provide a 2 A method for synthesizing polylactic acid in a fluid to overcome the shortcomings of high polymerization temperature, large side reactions, and heavy secondary pollution in the prior art
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Embodiment 1
[0035] A. Clean and dry the reactor, and pass through CO dried through 3 Å molecular sieves. 2 gas;
[0036] B. adding concentration is 0.25mol / L L-lactide, catalyst stannous isooctanoate and co-solvent, wherein the molar ratio of L-lactide and stannous isooctanoate is 1000:1, the molar ratio of co-solvent and L-lactide The ratio is 0:1;
[0037] C. Seal the reactor and heat it until the temperature reaches 85°C, and control the pressure in the reactor to 25Mpa;
[0038] D. Start the stirrer and react for 24 hours;
[0039] E. Pass cooling water, and control the temperature at 40°C, continue to stir, pass dry CO 2 Gas, flow control at 1000ml / hour, pressure at 20Mpa, supercritical extraction for 6 hours;
[0040] F. Through cooling water, the reaction kettle is lowered to room temperature, and the pressure is reduced to normal pressure, and the product is taken out, which is polylactic acid.
[0041] The weight average molecular weight of the product M w It is 43000, and ...
Embodiment 2
[0043] The concentration of L-lactide is 0.5mol / L, all the other conditions are with embodiment 1, obtain white powder product after the polymerization reaction, M wis 75000 and the PDI is 2.04.
Embodiment 3
[0045] The consumption of catalyzer is 1 / 500 of lactide, all the other conditions are with embodiment 1, obtain polylactic acid after polymerization reaction, M w is 74000 and the PDI is 2.16.
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Abstract
A synthesis of polylactic acid in super-critical CO2 fluids iscarried out by: adjusting mono-lactide' concentration in a reaction kettle, catalyst and cosolving reagent and its concentration, adjusting reaction temperature, CO2 pressure, reaction time, CO2 purity etc. conditions, to obtain polylactic acid with different molecular weights, and extracting and removing the non-reacted monomers, catalysts and cosolving reagents etc. low molecular weight substances with super-critical CO2 after reaction. The polylactic acid is obtained without post treatment and direct post processing. This invention has advantages of without pollution for products and environment, saving post treatment works, only through depressing operation to realize separating for products and CO2 solvent. It meets demands of current green world environmental protection and saves resources.
Description
technical field [0001] The invention belongs to the technical field of polymer materials, and in particular relates to a 2 Method for synthesizing polylactic acid in fluid. Background technique [0002] In recent years, in response to the problems of the earth's environment and petroleum resources, people are eager to develop a biodegradable polymer material that comes from nature and completely returns to nature. Polylactic acid and its copolymers, which use plant resources as raw materials, are exactly this type of completely biodegradable new materials. They also have good biocompatibility and bioabsorbability. Their applications have involved medical materials, food packaging, and agricultural films. and fiber materials. In particular, research on medical biodegradable materials has received the most attention and has been successfully applied in clinical applications. [0003] Polylactic acid is often synthesized by two methods: (1) direct method, directly prepared f...
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