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Process and apparatus for recovering lactide from polylactide or glycolide from polyglycolide

A technology of polylactide and lactide, which is applied in the field of recovering lactide from polylactide or recovering glycolide from polyglycolide and the device field, can solve the problem that it is difficult to economically realize large-scale technical processes, discontinuous And other issues

Active Publication Date: 2014-05-07
UHDE INVENTA FISCHER
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage of this method is that the hydrolysis is a discontinuous process with water vapor in solid PLA
It is difficult to implement large-scale technological processes economically in this way

Method used

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  • Process and apparatus for recovering lactide from polylactide or glycolide from polyglycolide
  • Process and apparatus for recovering lactide from polylactide or glycolide from polyglycolide
  • Process and apparatus for recovering lactide from polylactide or glycolide from polyglycolide

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0146] This example shows the basic applicability of the combination of cyclodepolymerization and hydrolysis for the conversion of PLA to crude lactide.

[0147] In a stainless steel laboratory pressure vessel lined with PTEE and closed, 30 g of PLA with an I.V of 1.80 dl / g (equivalent to a weight average molar mass of 230,000) was mixed with water in an amount of 0.70 g. The container was placed in a circulating air drying oven maintained at 190°C. After 6 hours, the autoclave was removed from the dry box and allowed to cool at room temperature. The container was opened and the resulting viscous material was removed and analyzed.

[0148] It was found by titration that the carboxyl end group concentration was 1250, corresponding mathematically to a molar mass of 800 Da.

[0149] In a three-necked glass flask, 20 g of the viscous substance was mixed with 0.184 mg of tin octoate with a stirrer and dissolved in toluene. After applying a vacuum of 5 mbar, the glass flask was w...

Embodiment 2

[0152] This example shows the effect of the method of the present invention. according to Figure 4 An extruder 1 was set up in the plant so that it took in and melted 1.5 kg / h of pulverized PLA waste product. The waste product showed an average I.V. of 1.64 dl / g (chloroform, 30°C).

[0153] The pressurization valve 8 at the end of the pipe section 2 is set to 30 bar. The melt temperature at the exit of the extruder was 210°C. By means of the metering pump 5 , 26.9 g / h of demineralized water are forced through the capillary 4 into the melt at the beginning of the pipe section. A sample of the melt after pressurization valve 8 showed a carboxyl end group concentration of 960 mmol / kg.

[0154] At the end of pipe section 2, metering pump 7 delivers 300 ppm Sn (as tin octoate) through capillary 6 to the hydrolyzed melt. In the depolymerization reactor 9, the melt temperature was set to 220°C. 70 g / h of liquid residue were removed from the reactor and 1,410 kg / h of crude lact...

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Abstract

The present invention relates to a process for recovering lactide from polylactide (PLA) or glycolide from polyglycolide (PGA), in which, in a first step, PLA or PGA is contacted with a hydrolysing medium and hydrolytically degraded to oligomers. In a further step, a cyclising depolymerisation of the oligomers obtained in the first step is effected to give lactide or glycolide. In addition, the present invention relates to an apparatus based on the combination of a hydrolysis apparatus with a depolymerisation reactor, with which the above-described process can be performed. The core of the process according to the invention is a partial hydrolysis of the polymeric materials originally used in combination with a cyclising depolymerisation.

Description

technical field [0001] The present invention relates to a method for recovering lactide from polylactide (PLA) or recovery of glycolide from polyglycolide (PGA), wherein, in a first step, PLA or PGA is brought into contact with a hydrolysis medium to hydrolyze degraded into oligomers. In a further step, the oligomer obtained in the first step undergoes cyclodepolymerization to form lactide or glycolide. Furthermore, the invention relates to a device based on a combination of a hydrolysis device and a depolymerization reactor, with which the above-mentioned process can be carried out. The core of the process according to the invention is the combination of partial hydrolysis and cyclodepolymerization of the initially used polymeric material. Background technique [0002] It is known that PLA is decomposed into lactic acid by complete hydrolysis with water or aqueous lactic acid, and that after corresponding purification the lactic acid can be converted back into PLA in a kn...

Claims

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Application Information

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IPC IPC(8): C08J11/10C08J11/24C08J11/26B01J19/00B01J19/20C07C51/09C07C59/06C07C59/08B29C47/10B29C48/64
CPCB29K2105/0005B01J19/0013B01J19/20C08J11/10C08J11/24C08J11/26B01J2219/00006B01J2219/0004C08J2367/04B29B7/42B29K2067/043B29K2067/046B29C48/92B29C2948/92704B29C48/29B29C48/03B29C48/277B29C48/285B29C48/37B29C48/385B29C48/64C08G63/08C07D319/12B29B7/007B29B7/48B29B7/72B29B7/82B29B7/845Y02P70/10B01J19/00C07C51/09C07C59/06C07C59/08Y02W30/62
Inventor 赖纳·哈根
Owner UHDE INVENTA FISCHER
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