Continuous high vacuum rectification and purification method for lactide

A lactide and rectification technology, applied in continuous high vacuum distillation and purification of lactide, continuous high vacuum distillation, lactide purification field, can solve the problems of increasing equipment investment and operation difficulty, environmental pollution, etc. Achieve the effect of saving raw materials, reducing production costs, and making simple

Inactive Publication Date: 2010-10-13
CHANGZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0010] The defective and the deficiency that exist in above-mentioned prior art are: (1) will reclaim solvent and hydrolyzat

Method used

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  • Continuous high vacuum rectification and purification method for lactide
  • Continuous high vacuum rectification and purification method for lactide
  • Continuous high vacuum rectification and purification method for lactide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] The diameter of the first rectification column is 400mm, filled with DN25 plum blossom flat ring packing, 12 theoretical plates, and the material is fed to the ninth block; the second rectification tower has a diameter of 300mm, filled with DN25 plum blossom flat ring packing, and 15 theoretical plates , feeding in the seventh block; the diameter of the third rectifying column is 500mm, filled with DN25 plum blossom flat ring packing, 8 theoretical plates, feeding in the sixth block. The processing capacity of the lactide crude liquid is 680kg / h, and the composition is 82% lactide, 9% water and lactic acid, 6% meso-lactide and 3% lactic acid oligomers, and the feed liquid temperature After mixing with the return material of the second rectification tower, it enters the ninth theoretical plate of the first rectification tower. The operating conditions of the tower are shown in Table 1, and the composition of the top and bottom materials is shown in Table 4. The bottom ma...

Embodiment 2

[0043] The lactide crude liquid treatment capacity is reduced to 600kg / h, and the composition is 85% lactide, 6.8% water and lactic acid, 6.5% meso-lactide and 1.7% lactic acid oligomers, other conditions With embodiment 1, operation result is shown in table 6 and table 7. The purity of lactide after refining reaches 99.52%, and the yield is 94.1%.

[0044] Table 6 The composition of the top and bottom materials of each tower when the treatment capacity is 600kg / h

[0045]

[0046] Note: The low boilers in Table 6 refer to water, lactic acid and meso-lactide.

[0047] Table 7 Feed to each tower and material flow at the top and bottom of the tower when the processing capacity is 600kg / h

[0048]

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Abstract

The invention discloses a method for continuously rectifying and purifying the lactide with high yield rate, which belongs to the field of chemical and industrial rectification and purification. The method comprises the following steps of removing low-boiling point components particularly including water, lactic acid and partial meso-lactide on a tower top through the vacuum operation of a first rectification tower; removing all the meso-lactide on a tower top through the vacuum operation of a second rectification tower; and obtaining high-purity lactide products on the tower top through the vacuum operation of a third rectification tower, wherein the first rectification tower has 12 theoretical plates, 8 rectification sections and 8 stripping sections; the second rectification tower has 15 theoretical plates, 6 rectification sections and 9 stripping sections; and the third rectification tower has 8 theoretical plates, 5 rectification sections and 3 stripping sections. All the three towers provide back flow in the mode of internal back flow. In the invention, the purity of the lactide is higher than 99%, and the yield rate is higher than 90%. Continuous operation is realized so that the quality of the products is stable, raw materials are saved and the production cost is reduced.

Description

Technical field: [0001] The invention belongs to the field of chemical distillation and purification, and relates to a continuous high-vacuum distillation and purification method for lactide. Method for purifying lactide. Background technique: [0002] Polylactic acid is a new type of biodegradable polymer synthetic material obtained by ring-opening polymerization using lactide as raw material. Polylactic acid is non-toxic, non-irritating, has good biocompatibility, and can be biodegraded and absorbed. It is a high-strength, easy-to-process synthetic biodegradable polymer material with a wide range of uses. At present, the large-scale industrial production methods of polylactic acid are the ring-opening polymerization of lactide, that is, lactide is first prepared from lactic acid, and then polylactic acid is obtained by ring-opening polymerization of lactide as a monomer. The prepared lactide crude liquid often contains impurities such as water, lactic acid, meso-lactide,...

Claims

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Application Information

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IPC IPC(8): C07D319/12B01D3/10B01D3/14
Inventor 杨德明
Owner CHANGZHOU UNIV
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