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Method for recycling polylactic acid mixed plastic

A technology of mixing plastics and polylactic acid, which is applied in the direction of plastic recycling, recycling technology, chemical instruments and methods, etc., can solve the problems that the chemical recycling method of polylactic acid cannot meet the requirements of recycling polylactic acid mixed plastics, and achieve low environmental hazards and good bottom Universal applicability, good depolymerization effect

Pending Publication Date: 2022-06-07
QINGDAO INST OF BIOENERGY & BIOPROCESS TECH CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The present invention aims at the problem that the existing polylactic acid chemical recovery method cannot satisfy the recovery of polylactic acid mixed plastics, and provides a method for recycling polylactic acid mixed plastics

Method used

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  • Method for recycling polylactic acid mixed plastic
  • Method for recycling polylactic acid mixed plastic
  • Method for recycling polylactic acid mixed plastic

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] Example 1: Sequential depolymerization of plastic bags of PLA / PBAT. The reaction process is as follows:

[0029]

[0030] The first step: depolymerization of polylactic acid in the plastic bag of PLA / PBAT. The specific operation process is as follows:

[0031] (1) Take a 100 mL Schlenk bottle, bake it and replace the argon gas, add 12 g of plastic bag fragments in the glove box, add 40 mL of methanol (988 mmol), add 40 mL of dichloromethane solvent, and add 0.6 g of Zn[N (SiMe 3 ) 2 ] 2 Catalyst (5 wt.%), the reaction was stirred at room temperature in a fume hood.

[0032] (2) After 2 hours of reaction, sampling was carried out for NMR monitoring. The results showed that PLA was depolymerized and all converted into methyl lactate, while PBAT was almost not depolymerized, and the characteristic peak of PBAT methanolysis product could not be detected by NMR.

[0033] (3) Separation of product methyl lactate and unreacted PBAT: methanol was added to the reaction s...

Embodiment 2

[0041] Example 2: Plastic bag one-pot depolymerization of PLA / PBAT. The reaction process is as follows:

[0042]

[0043] The specific operation process is as follows:

[0044] (1) Take a 100 mL Schlenk bottle, bake it and replace the argon gas, add 12 g (57.1 mmol polymer repeating unit) pieces of plastic bag in the glove box, add 40 mL methanol (988 mmol, 8.7 eq. relative to the polymer ester group), add 40 mL of toluene, add 0.6 g of Zn[N (SiMe 3 ) 2 ] 2 Catalyst (5 wt. %, 1.6 mmol, 2.8 mol % to polymer repeat unit), the reaction was stirred at 100°C in a fume hood.

[0045] (2) After 9 hours of reaction, sampling was carried out for nuclear magnetic detection. The results showed that the conversion rate of PLA was 100%, and the yield of methyl lactate was 100%. The conversion of PBA unit was 78%, the conversion of PBT unit was 95%, and the yield of DMT was 95%.

[0046] (3) separation of reaction product:

[0047] ①Use a vacuum pump to extract and collect lower b...

Embodiment 3

[0050] Example 3: Pipette sequential depolymerization of PLA / PBS. like figure 1 As shown, the reaction process is as follows:

[0051]

[0052] The first step: depolymerization of polylactic acid in the straw of PLA / PBS, the specific operation process is as follows:

[0053] (1) Take a 100 mL Schlenk bottle, bake it and replace the argon gas, add 12 g of pipette fragments in the glove box, add 40 mL of methanol (988 mmol), add 40 mL of dichloromethane solvent, and add 0.6 g of Zn[N ( SiMe 3 ) 2 ] 2 Catalyst (5 wt.%), the reaction was stirred at room temperature in a fume hood.

[0054] (2) After 2 h of reaction, sampling was carried out for NMR monitoring. The results showed that PLA was depolymerized and all converted into methyl lactate, while PBS was almost not depolymerized, and the characteristic peaks of PBAT methanolysis products could not be detected by NMR.

[0055] (3) Separation of product methyl lactate and unreacted PBS: n-hexane was added to the reaction...

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Abstract

The invention discloses a method for recycling polylactic acid mixed plastic, and belongs to the technical field of plastic degradation and recycling. The problem that an existing polylactic acid chemical recovery method cannot meet the requirement for recovery of polylactic acid mixed plastic is solved. The zinc catalyst with a simple structure is adopted for catalysis, depolymerization of the polylactic acid mixed plastic is realized under the participation of the alcohol compound, sequential depolymerization can be performed according to the difference of reaction activity among different plastics in the depolymerization process, and a depolymerization product can be separated and recycled after the plastics are depolymerized by a one-pot method. According to the method, degradation of the polylactic acid mixed plastic is efficiently, simply and conveniently realized, and the polylactic acid mixed plastic can be depolymerized into small organic molecules under mild conditions, so that recycling of waste plastic is realized.

Description

technical field [0001] The invention relates to a method for recycling polylactic acid mixed plastics, and belongs to the technical field of plastic degradation and recycling. Background technique [0002] Because of its irreplaceable advantages such as high strength, durability and lightness, plastics are widely used in various fields such as industry, transportation, and communication, which greatly promotes social progress and improves human living standards. But white pollution from mass-produced waste plastics has also become a thorny environmental issue. In recent years, with the enhancement of people's awareness of environmental protection, degradable polyester represented by polylactic acid has been greatly developed. [0003] Polylactic acid can be degraded into water and carbon dioxide through composting, but this process is actually a process of carbon emission, which still has an impact on the environment. The conversion of polylactic acid into other high value...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C67/03C07C69/68C07C69/82C07C69/44C07C69/40C07C69/675C07C68/06C07C69/96C07C29/128C07C31/20C07C37/055C07C39/16
CPCC07C67/03C07C68/06C07C29/1285C07C37/0555C07C69/68C07C69/82C07C69/44C07C69/40C07C69/675C07C69/96C07C31/202C07C31/207C07C39/16Y02W30/62
Inventor 王庆刚徐广强杨茹琳
Owner QINGDAO INST OF BIOENERGY & BIOPROCESS TECH CHINESE ACADEMY OF SCI
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