Method for continuously refining L-lactide from crude L-lactide

A technology of lactide and refining tower, which is applied in the direction of organic chemistry and can solve problems such as difficult operation

Inactive Publication Date: 2010-04-21
南京冠创生物科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, it is still very difficult to install the column on th...

Method used

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  • Method for continuously refining L-lactide from crude L-lactide
  • Method for continuously refining L-lactide from crude L-lactide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] The molecular weight of polylactic acid is controlled by the amount of hydroxyl impurities in lactide. Lactide containing different lactic acid impurities was polymerized into polylactic acid to illustrate the effect of lactic acid impurity content on the molecular weight of polylactic acid. Polymerization at 160°C using 0.1 wt% stannous octoate as catalyst in a dry inert atmosphere N 2 next.

[0045] Lactic acid impurity content (%wt)

Embodiment 2

[0047]The 80kg / h rectified lactide was continuously refined in the light-removing tower containing top stream, liquid bottom stream and the refining tower containing top stream, liquid bottom stream and steam side stream. Water, lactic acid and meso-lactide are concentrated in the top stream of the light removal tower, and L-lactide and lactic acid oligomers are concentrated in the bottom stream of the light removal tower. Then, the bottom flow of the light removal tower is sent to the middle part of the refining tower through the feeding pump. The L-lactide is concentrated in the top stream of the refining tower, and the lactic acid oligomers are concentrated in the bottom stream of the refining tower, and the obtained L-lactide can be directly polymerized without further refining to obtain high molecular weight polylactic acid. In order to enhance the contact between vapor and liquid and minimize liquid column storage, structural packing materials are used to fill the light ...

Embodiment 3

[0053] The 80kg / h rectified lactide was continuously refined in the light-removing tower containing top stream, liquid bottom stream and the refining tower containing top stream, liquid bottom stream and steam side stream. Water, lactic acid and meso-lactide are concentrated in the top stream of the light removal tower, and L-lactide and lactic acid oligomers are concentrated in the bottom stream of the light removal tower. Then, the bottom flow of the light removal tower is sent to the middle part of the refining tower through the feeding pump. A small amount of by-products such as water, lactic acid and meso-lactide are concentrated in the top stream of the refining tower, lactic acid oligomers are concentrated in the bottom stream of the refining tower, and L-lactide is discharged through the steam side stream of the refining tower, containing L-lactide The vapor side stream of the refining tower of lactide has almost no lactic acid and lactic acid oligomers, and can be dir...

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Abstract

The invention discloses a method for continuously refining L-lactide from crude L-lactide, which comprises the following steps of: firstly, performing at least once lightness removal to the crude L-lactide by using a lightness-removing column, sending melted crude L-lactide into the middle of the lightness-removing column, refluxing and separating as well as distilling the crude L-lactide in the lightness-removing column, condensing vapor distillate at the upper end of the lightness-removing column for removing water, L-lactate and meso-lactide; secondly, enabling column bottom liquid to enter a reboiler for vaporization and then enter into the column, performing at least once rectification to the left column bottom liquid through a treating column after cooling, wherein the lower end of the lightness-removing column mainly has high-boiling point distillate liquid comprising the L-lactide and lactate oligomer; and when in rectification, refluxing and separating the column bottom liquid of the lightness-removing column to obtain a refined L-lactide; refining column bottom flow to obtain concentrated lactate oligomer. The L-lactide purified by the method can be directly used in the polymerization of poly L-lactate, thereby lowering the purifying cost of the L-lactide, increasing the yield, and being environmental friendly without organic solvents.

Description

1. Technical field [0001] The present invention relates to a process for refining L-lactide from a crude L-lactide vapor product stream comprising at least L-lactide, meso-lactide, water, L-lactic acid and lactic acid oligomers. 2. Background technology [0002] Poly-L-lactic acid, also known as poly-L-lactide, is an important biodegradable material with degradability, biocompatibility, good mechanical properties and processability, and has been widely used in Many areas. At present, there are mainly two synthetic routes, namely direct condensation polymerization of lactic acid and ring-opening polymerization via L-lactide intermediate. The direct condensation polymerization (one-step process) of lactic acid is a short and high-yield process, but involves the removal of water during condensation and the use of solvents at high vacuum and high temperature. Due to the existence of water and impurities, this method can only produce polylactic acid with low relative molecular ...

Claims

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Application Information

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IPC IPC(8): C07D319/12
Inventor 邹俊芦武刚陈悬舒友姜徐斌郭彦斌
Owner 南京冠创生物科技有限公司
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