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Method for recovering polyimide by selectively breaking imide bond

A polyimide and imide technology, which is applied in the field of recycling and recycling of waste polymer materials, can solve problems such as unfavorable industrialization, high pressure, and complex degradation process.

Pending Publication Date: 2021-09-10
SHANXI INST OF COAL CHEM CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] The first type of method using ammonia water to hydrolyze polyimide requires high pressure, and ammonia water is highly volatile, which is not conducive to realizing industrialization
Using hydrazine hydrate to recover polyimide, the subsequent treatment process of degradation products is relatively complicated
The second type uses sodium hydroxide or potassium hydroxide aqueous solution to reclaim the method of polyimide, and the degradation process is more complicated, and the product that obtains is unknown small molecule compound

Method used

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  • Method for recovering polyimide by selectively breaking imide bond
  • Method for recovering polyimide by selectively breaking imide bond
  • Method for recovering polyimide by selectively breaking imide bond

Examples

Experimental program
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Effect test

Embodiment 1

[0034] In the present embodiment, a method for selectively breaking imide bonds to reclaim polyimide comprises the following steps:

[0035] Mix water and m-cresol in a mass ratio of 1:1 to form a mixed solution, prepare the mixed solution and LiOH at a catalyst mass fraction of 20% to form a reaction system I, and mix the polyimide material and reaction system I in a mass ratio of 1:1 Mixed and added to the reactor, sealed and placed in a homogeneous reactor heated to 220 ° C, reacted for 7h. After the reaction is completed, cool to room temperature, filter, add deionized water to wash the filter cake to obtain 4,4'-diaminodiphenyl ether; distill off the organic solvent in the filtrate, add hydrochloric acid to precipitate aromatic phthalic acid, filter and dry After that, pyromellitic acid was obtained.

[0036] figure 1 It is the carbon nuclear magnetic resonance spectrum of the pyromellitic acid monomer recovered; figure 2 It is the carbon nuclear magnetic resonance sp...

Embodiment 2

[0038] In the present embodiment, a method for selectively breaking imide bonds to reclaim polyimide comprises the following steps:

[0039] Water and N,N'-dimethylacetamide are formulated into a mixed solution at a mass ratio of 1:5, and the mixed solution and (CH 3 ) 4 NOH is formulated into reaction system Ⅰ according to the catalyst mass fraction of 30%. Mix the polyimide material and reaction system Ⅰ according to the mass ratio of 1:10 and add it to the reaction kettle. After sealing, place it in a homogeneous reactor and heat it to 110°C for 6 hours. . After the reaction is completed, cool to room temperature, filter, add deionized water to wash the filter cake, and obtain 4,4'-diaminodiphenylmethane, whose carbon nuclear magnetic resonance spectrum is shown in image 3 ; Evaporate the organic solvent in the filtrate, add hydrochloric acid to precipitate the aromatic phthalic acid, and obtain pyromellitic acid after filtering and drying.

Embodiment 3

[0041] In the present embodiment, a method for selectively breaking imide bonds to reclaim polyimide comprises the following steps:

[0042]Mix water and N-methylpyrrolidone at a mass ratio of 1:8 to form a mixed solution, prepare the mixed solvent and CsOH at a catalyst mass fraction of 20% to form reaction system I, and mix polyimide material and reaction system I at a mass ratio of 1 :30 mixed and added to the reactor, sealed and placed in a homogeneous reactor heated to 160 ° C, reacted for 7h. After the reaction was completed, it was cooled to room temperature, filtered, and deionized water was added to wash the filter cake to obtain p-phenylenediamine, whose carbon nuclear magnetic resonance spectrum was shown in Figure 4 ; Evaporate the organic solvent in the filtrate, add hydrochloric acid to precipitate the aromatic phthalic acid, and obtain biphenyl tetracarboxylic acid after filtration and drying.

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Abstract

The invention belongs to the field of recycling of waste high polymer materials, and particularly relates to a method for recovering polyimide by selectively breaking imide bonds. The method comprises the following steps: preparing a reaction system by using polyimide waste, a solvent and a catalyst, and placing the reaction system in a homogeneous reactor for degradation reaction; filtering after degradation is completed, and adding deionized water to wash a filter cake to obtain aromatic diamine; and evaporating out the solvent in the filtrate, and adding hydrochloric acid to obtain aromatic phthalic acid. According to the invention, the imide bonds are selectively broken by using a basic catalyst to obtain the aromatic diamine and the aromatic pyromellitic acid. The method has the advantages of simple operation process, low recovery cost and easiness in separation to obtain high-added-value products.

Description

technical field [0001] The invention belongs to the field of recycling and resource utilization of waste polymer materials, and in particular relates to a method for selectively breaking imide bonds to recover polyimide. Background technique [0002] Polyimide is one of the organic polymer materials with the best comprehensive performance. It can be used for a long time in the range of -200 ~ 300 ℃, has excellent wear resistance, chemical corrosion resistance and electrical insulation, etc., and has been widely used in aviation, aerospace, microelectronics, nano, liquid crystal, separation membrane, laser, etc. field. At the same time, the extensive use of polyimide has led to an increase in waste resources, and its recycling has also attracted widespread attention. [0003] Polyimides are mainly prepared from aromatic diamines and aromatic dianhydrides. However, the preparation process of aromatic diamines and aromatic dianhydrides is complex and expensive, so recycling ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C51/06C07C63/313C07C65/24C07C213/02C07C217/90C07C209/62C07C211/50C07C211/51
CPCC07C51/06C07C213/02C07C209/62C07C63/313C07C65/24C07C217/90C07C211/50C07C211/51
Inventor 侯相林田梓赏王玉琪毛昳萱
Owner SHANXI INST OF COAL CHEM CHINESE ACAD OF SCI
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