A kind of purification system and purification method of lactide
A technology of lactide and rectifying tower, applied in the purification of lactide, the field of purification system of lactide, can solve the problem of low total yield of lactide, difficult control of amount and hydrolysis time, long purification cycle, etc. question
Active Publication Date: 2020-10-27
安徽丰原福泰来聚乳酸有限公司
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Problems solved by technology
Because lactide can also undergo hydrolysis reaction, it is difficult to control the amount of water added to purify lactide and the hydrolysis time by this method, and the purity of the obtained lactide cannot meet the requirements of polymerization, and further purification is required
[0006] Third, the recrystallization method, which is currently the most studied method in lactide purification technology, is also a commonly used method in the purification process of organic matter. The purification cycle of this method is relatively long, and multiple purifications are required to achieve polymerization. The required purity, the existing problem is that after repeated recrystallization and purification, the total yield of lactide is low, and a large amount of organic solvents such as alcohols or lipids need to be used, which involves the problem of solvent recovery and will bring environmental pollution
Although many researchers are committed to the research in this area and have made considerable progress, if it is put into mass production, there is still a lot of work to be done on the continuity of production, yield, recovery rate and cost.
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Embodiment 1
[0047] The content of crude lactide treated in this embodiment is 89%, the moisture content is 0.01%, the content of Meso-lactide is 4%, the content of lactic acid is 2.25%, and the content of other impurities is 4.5%;
[0048] The crude lactide enters the rectification tower 3 after being preheated by the first heat exchanger 2 from the first material delivery pump 1, and the temperature of the crude lactide after preheating is 115°C;
[0049] In this embodiment, the temperature at the top of rectification tower 3 is 120°C, the pressure at the top of the tower is 600Pa, the temperature at the bottom of the tower is 140°C, and the pressure at the bottom of the tower is 2000Pa;
[0050] In this embodiment, after the crude lactide enters the rectifying tower 3, it moves from top to bottom under the action of gravity, and enters the reboiler 5 from the top of the reboiler 5 through the second material delivery pump 6, and the inside of the reboiler 5 The temperature of the crude ...
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The invention belongs to the technical field of polylactic acid production, particularly discloses a lactide purification system, and also discloses a lactide purification method. The purification method comprises a rectification step, a melt crystallization step and a recrystallization step. Crude lactide is firstly rectified and purified to obtain a lactide gas, and the lactide gas is condensedto obtain medium-purity lactide; the medium-purity lactide enters a falling-film crystallizer and undergoes melt crystallization, and a non-condensable liquid and a pure lactide product are obtained through separation; and the obtained non-condensable liquid is recrystallized, and products obtained after recrystallization separation respectively enter different recycling treatments due to different purities. The purification method has a high lactide purification yield, and the purity of the lactide product obtained by purification is high.
Description
technical field [0001] The invention relates to the technical field of polylactic acid production, in particular to a lactide purification system and a lactide purification method. Background technique [0002] Polylactic acid (abbreviated as "PLA") is further polymerized from lactic acid produced by fermentation of starch or sugar. Polylactic acid does not use petroleum as raw material. It is environmentally friendly, non-toxic, antibacterial, flame retardant, good biocompatibility and biodegradable It is considered to be the most promising new material to shake the traditional status of petroleum-based plastics and chemical fibers in the future. At present, the production process of polylactic acid mainly includes "one-step method" and "two-step method". "One-step method" uses a solvent under vacuum conditions to directly dehydrate and polycondense lactic acid. This method is used to produce polylactic acid. During the polymerization process, the polycondensation reaction...
Claims
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IPC IPC(8): C07D319/12C08G63/08
CPCC07D319/12C08G63/08
Inventor 李远马丁·范·冈斯伯格张宏才徐业生
Owner 安徽丰原福泰来聚乳酸有限公司