A method for recycling waste polymer materials containing ester group / amide bond / imide bond

Abstract

The application discloses a recycling method of waste polymer materials containing ester bond / amide bond / imide bond, which comprises the following steps: mixing the waste polymer materials containing ester bond / amide bond / imide bond with an organic amine, stirring and reacting, separating by distillation or reduced pressure distillation after the reaction, and recycling the obtained organic amine, wherein the degradation product can be directly used as a functional material, or the degradation product is mixed with an acid solution or an alkali solution for stirring and reacting, and the monomer and the filtrate are separated by filtering or distillation, the pH of the filtrate is adjusted to alkaline or acidic, and another monomer is recycled by continuing filtering or distillation. The application can efficiently degrade the waste polymer materials containing ester bond / amide bond / imide bond under normal pressure and low temperature conditions, and recycle all the degradation products, and has the advantages of low recycling cost, short period, high efficiency, low energy consumption, simple and safe operation and suitability for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of chemical recycling technology for waste polymer materials, specifically relating to a method for recycling waste polymer materials containing ester groups / amide bonds / imide bonds. Background Technology

[0002] Polymers containing ester / amide / imide bonds typically possess excellent properties and are widely used in various fields. Taking polyimide as an example, its excellent thermal stability and mechanical properties make it widely used in semiconductors, electronics, nanomaterials, flexible displays, and lasers. As the application scope of polymers containing ester / amide / imide bonds expands, their demand continues to rise, leading to a significant increase in waste materials and scraps generated at the end of their lifespan. The accumulation of these massive amounts of polymers in the natural environment not only poses a serious threat to human health and the ecological environment but also results in severe resource waste. However, due to their excellent chemical stability, these polymers are difficult to degrade and recycle. Therefore, finding a simple and convenient method to effectively degrade these polymer wastes, reducing environmental pollution while achieving the reuse of these resources, has become an urgent problem to be solved.

[0003] Compared to mechanical and energy recovery, chemical recovery is currently the most promising method because it can selectively break ester, amide, or imide bonds in polymer materials through solvation, yielding high-value products. However, existing solvation systems typically require harsh reaction conditions. For example, CN103553906B discloses a method for recovering polyimide raw materials by hydrolyzing waste polyimide films with ammonia. This method uses 25-30% ammonia in a hydrolysis autoclave at 200°C and 1.4 MPa to hydrolyze polyimide films to recover monomers. While this method has a high monomer recovery rate, it suffers from the need for high-temperature and high-pressure reaction conditions and the problem of ammonia leakage. Huang Fen et al. disclosed a method for catalytic depolymerization of polyimide in subcritical water using NaOH as a catalyst (Industrial & Engineering Chemistry Researching, 2012, 51, 7001-7006). While this method can degrade thermoplastic polyimides in low-concentration alkaline solutions, the reaction products are complex and difficult to separate. Furthermore, the reaction requires a high-pressure reactor, placing high demands on the equipment and significantly increasing production costs, making it difficult to promote its practical application. For example, CN109503614 B discloses a method for recycling polyimide waste, which uses hydrazine hydrate to aminodegrade the waste under normal pressure. Although this method can be performed at normal pressure, the subsequent processing is complex, the use of hydrazine hydrate poses certain risks, and the reaction process requires nitrogen protection. Another example is CN1324789A, which discloses a hydrolysis recovery method for polyimides. This method involves heating polyimides under reflux in an alkaline solution for 8–15 hours to recover diamines and dianhydrides. Although this method achieves a monomer recovery rate of over 80%, it suffers from problems such as high alkali consumption, long reaction time, and high production costs.

[0004] Therefore, it is particularly important to develop a method that can effectively degrade and fully recycle polymer materials containing ester / amide / imide bonds under mild conditions. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the current chemical recycling of waste polymer materials containing ester groups / amide bonds / imide bonds, and to provide a recycling method for waste polymer materials containing ester groups / amide bonds / imide bonds. This method can efficiently degrade waste polymer materials containing ester groups / amide bonds / imide bonds under mild conditions, and can also recover and reuse all degradation products and reaction reagents.

[0006] The present invention provides a method for recycling waste polymer materials containing ester groups / amide bonds / imide bonds. The process steps and conditions of this method are as follows: 1) First, mix the waste polymer material containing ester groups / amide bonds / imide bonds with organic amines at a mass ratio of 1:1 to 80, and then stir and react at room temperature to 180°C for 20 min to 15 h; 2) After the reaction, the reagents and degradation products are separated directly by distillation or vacuum distillation. The recovered organic amines can be reused, and the degradation products can be directly used as functional materials, or After the reaction is complete, the reaction reagents and degradation products are separated directly by distillation or vacuum distillation. The recovered organic amine can be reused. The recovered degradation products are mixed with acid or alkaline solutions at a mass ratio of 1:1 to 30 and stirred at room temperature to 100°C for 10 min to 10 h. After the reaction is complete, the monomer and filtrate are separated by filtration or distillation. The pH of the filtrate is then adjusted to alkaline or acidic, and another monomer can be recovered by filtration or distillation.

[0007] The organic amine mentioned in the above methods is at least one of 3-amino-1-propanol, 2-amino-1-butanol, isopropanolamine, ethylenediamine, 1,4-butanediamine, 1,2-propanediamine, diisobutylamine, cyclohexylamine, aniline, butylamine, ethanolamine, diethanolamine, triethanolamine, and diethylenetriamine.

[0008] The waste polymer materials containing ester groups / amide bonds / imide bonds mentioned in the above methods are at least one of waste polyimide, waste ester-containing epoxy resin, waste polyester, waste polyurethane, waste polyamide and its waste composite materials.

[0009] The waste polyimide mentioned in the above methods is preferably phenylacetylene-type polyimide, bismaleimide, norbornene-type polyimide, pyromellitic polyimide, biphenyl-type polyimide, or polyetherimide; the waste ester-containing epoxy resin is preferably glycidyl ether epoxy resin, glycidyl ester epoxy resin, glycidyl amine epoxy resin, alicyclic epoxy resin, or epoxidized olefin epoxy resin; the waste polyester is preferably aliphatic polycarbonate, alicyclic polycarbonate, or aromatic polycarbonate, such as polyethylene terephthalate, polybutylene terephthalate, or polymethyl methacrylate. Methyl acrylate, poly(p-hydroxybenzoate), polylactic acid, polybutylene terephthalate-adipate, bisphenol A-terephthalate / isophthalic acid copolyester, bisphenol A type unsaturated polyester, orthophthalic type unsaturated polyester, isophthalic type unsaturated polyester, xylene type unsaturated polyester or vinyl ester resin; waste polyurethane is preferably toluene diisocyanate type polyurethane, diphenylmethane diisocyanate type polyurethane, isoflurone diisocyanate type polyurethane or hexamethylene diisocyanate type polyurethane; waste polyamide is preferably aliphatic polyamide, semi-aromatic polyamide or fully aromatic polyamide.

[0010] The acid solution mentioned in the above method is any one of hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, propionic acid, butyric acid or p-toluenesulfonic acid aqueous solution, with a mass concentration of 1 to 15 wt%; the alkaline solution is any one of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, ammonia, sodium carbonate or potassium carbonate aqueous solution, with a mass concentration of 1 to 15 wt%.

[0011] The pure resin in the waste polymer materials containing ester groups / amide bonds / imide bonds described in the above methods can be crushed into blocks or granules to facilitate degradation; while the composite materials in the waste polymer materials containing ester groups / amide bonds / imide bonds can be cut into blocks of appropriate length according to the length requirements of the recycled fibers, so that the fibers added to the composite materials can be recycled and reused.

[0012] The mass concentration of the acid solution described in the above method is preferably 1-10 wt%, more preferably 1-5 wt%.

[0013] The mass concentration of the alkaline solution described in the above method is preferably 1-10 wt%, more preferably 1-5 wt%.

[0014] In step 1) of the above method, the waste polymer material containing ester group / amide bond / imide bond is preferably mixed with organic amine in a mass ratio of 1:1 to 30, and then preferably reacted at room temperature to 140°C for 20 min to 5 h.

[0015] In step 1) of the above method, waste polymer materials containing ester groups / amide bonds / imide bonds are mixed with organic amines at a mass ratio of 1:1 to 30, and then preferably reacted at room temperature to 120°C for 20 min to 2 h.

[0016] In step 2) of the above method, the degradation product is preferably reacted with the acid solution or alkaline solution at room temperature to 60°C for 10 min to 2 h to recover the monomer.

[0017] Compared with the prior art, the present invention has the following advantages: 1. Since the recycling method for waste polymer materials containing ester groups / amide bonds / imide bonds provided by the present invention can be carried out under normal pressure, it is not necessary to purchase expensive high-pressure reactors, which can reduce recycling costs. Moreover, the operation under normal pressure is simpler and safer.

[0018] 2. Since the recycling method for waste polymer materials containing ester groups / amide bonds / imide bonds provided by this invention can be completely degraded in a short time under normal pressure, the recycling cycle is short, the efficiency is high, and it is more suitable for industrial recycling production. 3. Since the recycling method for waste polymer materials containing ester groups / amide bonds / imide bonds provided by the present invention can also be degraded at a lower temperature under the above conditions, it has low energy consumption and low cost.

[0019] 4. The degradation products recovered by the recycling method of waste polymer materials containing ester groups / amide bonds / imide bonds provided by the present invention can not only be used directly as functional materials, but can also be further reacted under normal pressure to recover monomers, thus making it more applicable and having greater utilization value.

[0020] 5. The recycling method for waste polymer materials containing ester groups / amide bonds / imide bonds provided by the present invention can not only fully utilize all the recycled degradation products, but also the organic amine solvent used in the reaction can be recycled and reused multiple times, and the amount of acid or alkali solution used is also less. Therefore, it can further reduce recycling costs and greatly reduce wastewater treatment costs. Attached Figure Description

[0021] The attached figure is the 1H NMR spectrum of the 4,4'-diaminodiphenyl ether monomer recovered in Example 28 of this invention. Detailed Implementation

[0022] The following embodiments are provided to further illustrate the present invention in detail. However, the following embodiments should not be construed as limiting the scope of protection of the present invention. If those skilled in the art make some non-essential improvements and adjustments to the present invention based on the content of the present invention, they shall still fall within the scope of protection of the present invention.

[0023] It is worth noting that: 1) All parts of materials mentioned in the following examples are by weight.

[0024] 2) The degradation rate of the pure waste polymer material in the examples was calculated using the following formula: D d = (W1-W0) / W1×100% In the formula: D d W1 represents the degradation rate; W1 represents the mass of the waste polymer material; W0 represents the mass of the solid residue obtained after filtering and separating the degradation liquid after the reaction, which is then subjected to ultrasonic water washing, alcohol washing, and drying.

[0025] 3) The degradation rate of the waste composite material in the examples was calculated using the following formula: D c =(W3-W2) / (1-ß)W3×100% In the formula: D c W3 is the degradation rate; W2 is the mass of the waste composite material; W3 is the mass of the solid material containing fibers obtained after filtering and separating the degradation liquid after the reaction, which is then subjected to ultrasonic water washing, alcohol washing and drying; β is the proportion of fibers in the waste composite material.

[0026] 4) The monomer yield in the examples was calculated using the following formula: Y=(µ×W5×M1) / (∂×W4×M2)×100% In the formula: Y is the monomer recovery rate; W4 is the total mass of waste polymer materials; M1 is the molecular weight of repeating units in waste polymer materials; ∂ is the proportion of resin in waste polymer materials; W5 is the mass of recovered monomers; M2 is the molecular weight of monomers; µ is the purity of monomers.

[0027] Example 1 First, one part of waste bismaleimide was immersed in 20 parts of 3-amino-1-propanol and stirred at 120˚C for 20 min. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover 3-amino-1-propanol and degradation products. 3-amino-1-propanol was reused, and the degradation products were used directly as functional materials.

[0028] The degradation rate in this embodiment is 99.8%.

[0029] Example 2 First, 10 parts of waste polyetherimide were immersed in 30 parts of 2-amino-1-butanol and stirred at 70˚C for 1 hour. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover 2-amino-1-butanol and degradation products. 2-amino-1-butanol was reused, and the degradation products were used directly as functional materials.

[0030] The degradation rate in this embodiment is 98.3%.

[0031] Example 3 Three parts of waste phenylacetylene-type thermosetting polyimide were first immersed in 10 parts of ethylenediamine and stirred and reacted at room temperature for 6 hours. After the reaction was completed, the degradation liquid and solid residue were first separated by filtration. Then, the degradation liquid was recovered by vacuum distillation to obtain ethylenediamine and degradation products. The ethylenediamine was reused and the degradation products were directly used as functional materials.

[0032] The degradation rate in this example is 100%.

[0033] Example 4 First, 1 part of waste phenylacetylene-type thermosetting polyimide was immersed in 80 parts of diethylenetriamine and stirred and mixed at 160˚C for 5 h. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover diethylenetriamine and degradation products. Diethylenetriamine was reused and the degradation products were used directly as functional materials.

[0034] The degradation rate in this example is 100%.

[0035] Example 5 First, 1 part of waste homopolymer polyimide film was immersed in 60 parts of diethylenetriamine and stirred and mixed at 180˚C for 3 h. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover diethylenetriamine and degradation products. Diethylenetriamine was reused and the degradation products were used directly as functional materials.

[0036] The degradation rate in this embodiment is 99.8%.

[0037] Example 6 First, one part of waste homopolymer polyimide film was immersed in 55 parts of 1,2-propanediamine and stirred at 140˚C for 8 h. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover 1,2-propanediamine and degradation products. 1,2-propanediamine was reused, and the degradation products were used directly as functional materials.

[0038] The degradation rate in this example is 97.9%.

[0039] Example 7 Two parts of waste homopolymer polyimide film were first immersed in 70 parts of aniline and stirred and mixed at 160˚C for 10 hours. After the reaction was completed, the degradation liquid and solid residue were first separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover aniline and degradation products. Aniline was reused and the degradation products were directly used as functional materials.

[0040] The degradation rate in this example is 98.0%.

[0041] Example 8 Six parts of waste polyethylene terephthalate were first immersed in 120 parts of aniline and stirred and mixed at 140˚C for 3 h. After the reaction was completed, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover aniline and degradation products. Aniline was reused and the degradation products were directly used as functional materials.

[0042] The degradation rate in this example is 100%.

[0043] Example 9 Three parts of waste bisphenol A type unsaturated polyester were first immersed in 60 parts of monoisopropanolamine and stirred and mixed at 175˚C for 5 h. After the reaction was completed, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover monoisopropanolamine and degradation products. Monoisopropanolamine was reused, and the degradation products were directly used as functional materials.

[0044] The degradation rate in this example is 92.8%.

[0045] Example 10 Five parts of waste phthalic unsaturated polyester were first immersed in 100 parts of diethylenetriamine and stirred and mixed at 100˚C for 12 h. After the reaction was completed, the degradation liquid and solid residue were first separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover diethylenetriamine and degradation products. Diethylenetriamine was reused and the degradation products were directly used as functional materials.

[0046] The degradation rate in this embodiment is 93.5%. Example 11 First, 1 part of waste polybutylene terephthalate (PET) was immersed in 10 parts of diethylenetriamine and stirred and mixed at 130˚C for 5 h. After the reaction was completed, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover diethylenetriamine and degradation products. Diethylenetriamine was reused, and the degradation products were used directly as functional materials.

[0047] The degradation rate in this embodiment is 95.5%.

[0048] Example 12 First, 1 part of waste polymethyl methacrylate was immersed in 60 parts of cyclohexylamine and stirred and mixed at 80˚C for 10 hours. After the reaction was completed, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover cyclohexylamine and degradation products. The cyclohexylamine was reused, and the degradation products were directly used as functional materials.

[0049] The degradation rate in this example is 100%.

[0050] Example 13 Three parts of waste polymethyl methacrylate were first immersed in 45 parts of 1,4-butanediamine and stirred at 140˚C for 7 h. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover 1,4-butanediamine and degradation products. 1,4-butanediamine was reused, and the degradation products were used directly as functional materials.

[0051] The degradation rate in this example is 100%.

[0052] Example 14 First, 25 parts of waste diphenylmethane diisocyanate polyurethane were immersed in 25 parts of ethanolamine and stirred and mixed at 155˚C for 3 h. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover ethanolamine and degradation products. Ethanolamine was reused and the degradation products were used directly as functional materials.

[0053] The degradation rate in this example is 93.7%.

[0054] Example 15 First, 1 part of waste toluene diisocyanate type polyurethane was immersed in 15 parts of 1,2-propanediamine and stirred at 110˚C for 6 h. After the reaction was completed, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover 1,2-propanediamine and degradation products. 1,2-propanediamine was reused, and the degradation products were used directly as functional materials.

[0055] The degradation rate in this example is 100%.

[0056] Example 16 First, 1 part of waste polybutylene terephthalate was immersed in 70 parts of aniline and stirred and mixed at 135˚C for 4 h. After the reaction was completed, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover aniline and degradation products. Aniline was reused and the degradation products were used directly as functional materials.

[0057] The degradation rate in this example is 93.4%.

[0058] Example 17 First, 1 part of waste polylactic acid was immersed in 30 parts of diethylenetriamine and stirred and mixed at 120˚C for 30 min. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover diethylenetriamine and degradation products. Diethylenetriamine was reused and the degradation products were used directly as functional materials.

[0059] The degradation rate in this example is 92.1%.

[0060] Example 18 First, 1 part of waste polybutylene terephthalate (PET) was immersed in 45 parts of ethylenediamine and stirred and mixed at 60˚C for 8 h. After the reaction was completed, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover ethylenediamine and degradation products. The ethylenediamine was reused, and the degradation products were directly used as functional materials.

[0061] The degradation rate in this example is 97.1%.

[0062] Example 19 First, 60 parts of waste poly(p-hydroxybenzoate) were immersed in 120 parts of ethylenediamine and stirred and mixed at 80˚C for 1 hour. After the reaction was completed, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover ethylenediamine and degradation products. The ethylenediamine was reused and the degradation products were used directly as functional materials.

[0063] The degradation rate in this example is 100%.

[0064] Example 20 First, 1 part of waste poly(p-hydroxybenzoate) was immersed in 40 parts of butylamine and stirred and reacted at room temperature for 10 h. After the reaction was completed, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover butylamine and degradation products. The butylamine was reused and the degradation products were used directly as functional materials.

[0065] The degradation rate in this embodiment is 98.7%.

[0066] Example 21 First, 10 parts of waste poly(p-hydroxybenzoate) were immersed in a mixed solution consisting of 30 parts of ethanolamine and 25 parts of cyclohexylamine. The mixture was stirred and reacted at 170˚C for 1 h. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover ethanolamine, cyclohexylamine and degradation products. Ethanolamine and cyclohexylamine were reused, and the degradation products were used directly as functional materials.

[0067] The degradation rate in this example is 100%.

[0068] Example 22 First, 1 part of waste poly(p-hydroxybenzoate) was immersed in a mixed solution consisting of 10 parts of monoisopropanolamine and 10 parts of diethylenetriamine. The mixture was stirred and reacted at 120˚C for 2 h. After the reaction was completed, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover monoisopropanolamine, diethylenetriamine and degradation products. Monoisopropanolamine and diethylenetriamine were reused, and the degradation products were used directly as functional materials.

[0069] The degradation rate in this embodiment is 98.9%.

[0070] Example 23 First, 1 part of waste aliphatic polyamide was immersed in a mixed solution consisting of 15 parts diethanolamine and 10 parts diethylenetriamine. The mixture was stirred and reacted at 170˚C for 5 h. After the reaction was completed, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover diethanolamine, diethylenetriamine and degradation products. Diethanolamine and diethylenetriamine were reused, and the degradation products were used directly as functional materials.

[0071] The degradation rate in this example is 77.3%.

[0072] Example 24 First, one part of waste bismaleimide carbon fiber composite material was immersed in 25 parts of 1,2-propanediamine and stirred and mixed at 110˚C for 8 h. After the reaction, the degradation liquid and solid material containing fibers were separated by filtration. Then, the degradation liquid was distilled to recover 1,2-propanediamine and degradation products. 1,2-propanediamine was reused, and the degradation products were used directly as functional materials.

[0073] The degradation rate in this example is 93.5%.

[0074] Example 25 First, 1 part of waste glycidyl ester epoxy resin carbon fiber composite material was immersed in 40 parts of diethanolamine and stirred and mixed at 170˚C for 5 h. After the reaction, the degradation liquid and solid material containing fibers were separated by filtration. Then, the degradation liquid was distilled under reduced pressure to recover diethanolamine and degradation products. Diethanolamine was reused and the degradation products were directly used as functional materials.

[0075] The degradation rate in this example is 92.4%.

[0076] Example 26 Ten parts of waste vinyl ester carbon fiber composite material were first immersed in 270 parts of 1,2-propanediamine and stirred at 105˚C for 12 h. After the reaction, the degradation liquid and solid material containing fibers were separated by filtration. Then, the degradation liquid was recovered by vacuum distillation to obtain 1,2-propanediamine and degradation products. The 1,2-propanediamine was reused, and the degradation products were directly used as functional materials.

[0077] The degradation rate in this example is 97.5%.

[0078] Example 27 Twenty parts of waste isophthalic unsaturated polyester carbon fiber composite material were first immersed in 400 parts of 3-amino-1-propanol and stirred at 120˚C for 8 h. After the reaction, the degradation liquid and solid material containing fibers were separated by filtration. Then, the degradation liquid was recovered by vacuum distillation to obtain 3-amino-1-propanol and degradation products. 3-amino-1-propanol was reused, and the degradation products were directly used as functional materials.

[0079] The degradation rate in this embodiment is 88.9%.

[0080] Example 28 First, one part of waste pyromellitic polyimide film was immersed in 20 parts of triethanolamine and stirred at 80˚C for 2 h. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was recovered by vacuum distillation to obtain triethanolamine and degradation products, and the triethanolamine was reused. One part of the degradation product was mixed with 10 parts of 3%wt sulfuric acid solution and stirred at 40˚C for 10 min. After the reaction, N,N'-bis(2,2-dihydroxyethyl)pyromellitic tetracarboxylic acid imide and filtrate were separated by filtration. The pH of the filtrate was then adjusted to alkaline, and 4,4'-diaminodiphenyl ether was recovered by filtration.

[0081] In this embodiment, the degradation rate was 95.4%, the recovery rate of N,N'-bis(2,2-bishydroxyethyl)pyromellitic acid imine was 74.1%, and the recovery rate of 4,4'-diaminodiphenyl ether was 92.3%.

[0082] Example 29 First, 20 parts of waste biphenyl-type polyimide film were immersed in 20 parts of ethanolamine and stirred at 60˚C for 2 h. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was recovered by vacuum distillation to obtain ethanolamine and degradation products, and the ethanolamine was reused. One part of the degradation product was mixed with five parts of 1%wt hydrochloric acid solution and stirred at 60˚C for 1 h. After the reaction, N,N'-bis(2-hydroxyethyl)biphenyltetracarboxylic acid imine and the filtrate were separated by filtration. The pH of the filtrate was then adjusted to alkaline, and 4,4'-diaminodiphenyl ether was recovered by filtration.

[0083] In this embodiment, the degradation rate was 89.7%, the recovery rate of N,N'-bis(2-hydroxyethyl)biphenyltetracarboxylic acid imine was 80.5%, and the recovery rate of 4,4'-diaminodiphenyl ether was 83.2%.

[0084] Example 30 Two parts of waste phenylacetylene-type thermosetting polyimide carbon fiber composite material were first immersed in 60 parts of ethylenediamine and reacted with stirring at room temperature for 15 h. After the reaction, the degradation liquid and solid material containing fibers were separated by filtration. Then, the degradation liquid was recovered by vacuum distillation to obtain ethylenediamine and degradation products, and the ethylenediamine was reused. Two parts of degradation products were mixed with two parts of 8%wt p-toluenesulfonic acid solution and reacted with stirring at room temperature for 4 h. After the reaction, N,N'-bis(2-aminoethyl)biphenyltetracarboxylic acid imine and filtrate were separated by filtration. The pH of the filtrate was then adjusted to alkaline, and 1,3-bis(4-aminophenoxy)benzene was recovered by filtration.

[0085] In this embodiment, the degradation rate was 98.3%, the recovery rate of N,N'-bis(2-aminoethyl)biphenyltetracarboxylic acid imine was 77.2%, and the recovery rate of 1,3-bis(4-aminophenoxy)benzene was 89.7%.

[0086] Example 31 Five parts of waste polylactic acid were first immersed in 50 parts of 2-amino-1-butanol and stirred at 180˚C for 2 h. After the reaction, the degradation solution and solid residue were separated by filtration. Then, the degradation solution was distilled under reduced pressure to recover 2-amino-1-butanol and the degradation product, and the 2-amino-1-butanol was reused. One part of the recovered degradation product was added to 30 parts of 5%wt phosphoric acid solution and stirred at 100˚C for 2 h. After the reaction, lactic acid was recovered by distillation.

[0087] In this embodiment, the degradation rate was 100%, and the lactic acid recovery rate was 83.4%.

[0088] Example 32 Three parts of waste norbornene-type thermosetting polyimide carbon fiber composite material were first immersed in 15 parts of diethylenetriamine and stirred at 160˚C for 13 h. After the reaction, the degradation liquid and solid material containing fibers were separated by filtration. The degradation liquid was then recovered by vacuum distillation to obtain diethylenetriamine and degradation products, and the diethylenetriamine was reused. One part of the recovered degradation product was added to 15 parts of 10%wt acetic acid solution and stirred at 90˚C for 5 h. After the reaction, biphenyltetracarboxylic acid and the filtrate were separated by filtration. The pH of the filtrate was then adjusted to alkaline, and trifluoromethyldiaminobiphenyl was recovered by filtration.

[0089] In this embodiment, the degradation rate was 98.4%, the recovery rate of biphenyltetracarboxylic acid was 72.9%, and the recovery rate of trifluoromethyldiaminobiphenyl was 92.0%.

[0090] Example 33 First, 3 parts of waste polyethylene terephthalate were immersed in 54 parts of monoisopropanolamine and reacted with stirring at 140˚C for 10 h. After the reaction, the degradation solution and solid residue were separated by filtration. Then, the degradation solution was recovered by vacuum distillation to obtain monoisopropanolamine and degradation products, and the monoisopropanolamine was reused. 3 parts of the degradation product were mixed with 9 parts of 15%wt propionic acid solution and reacted with stirring at 75˚C for 3 h. After the reaction, terephthalic acid was recovered by filtration.

[0091] In this embodiment, the degradation rate was 89.2%, and the phthalic acid recovery rate was 88.6%.

[0092] Example 34 Five parts of waste polymethyl methacrylate were first immersed in 100 parts of 1,4-butanediamine and stirred at 85˚C for 3 h. After the reaction, the degradation solution and solid residue were separated by filtration. The degradation solution was then distilled under reduced pressure to recover 1,4-butanediamine and the degradation product, and the 1,4-butanediamine was reused. Two parts of the degradation product were mixed with 40 parts of a 12%wt butyric acid solution and stirred at 45˚C for 1 h. After the reaction, methacrylic acid was recovered by distillation.

[0093] In this example, the degradation rate was 94%, and the methacrylic acid recovery rate was 85.9%.

[0094] Example 35 First, 1 part of waste polybutylene terephthalate was immersed in 25 parts of diisobutylamine and stirred at 90˚C for 1 h. After the reaction, the degradation solution and solid residue were separated by filtration. Then, the degradation solution was distilled under reduced pressure to recover diisobutylamine and degradation products, and the diisobutylamine was reused. 1 part of the degradation product was mixed with 1 part of 15%wt sodium hydroxide solution and stirred at 70˚C for 3 h. After the reaction, the pH of the filtrate was adjusted to acidic, and terephthalic acid was recovered by filtration.

[0095] In this embodiment, the degradation rate was 92.1%, and the phthalic acid recovery rate was 78.9%.

[0096] Example 36 First, 30 parts of waste bisphenol A type polycarbonate were immersed in 150 parts of triethanolamine and stirred at 150˚C for 4 h. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was recovered by vacuum distillation to obtain triethanolamine and degradation products, and the triethanolamine was reused. Two parts of the degradation product were mixed with 16 parts of 7%wt potassium hydroxide solution and stirred at 60˚C for 2 h. After the reaction, bisphenol A was recovered by filtration.

[0097] In this embodiment, the degradation rate was 94.8% and the bisphenol A recovery rate was 85.9%.

[0098] Example 37 First, one part of waste bisphenol A type polycarbonate was immersed in 45 parts of aniline and stirred at 135˚C for 2 h. After the reaction, the degradation liquid and solid residue were separated by filtration. Then, the degradation liquid was recovered by vacuum distillation to obtain aniline and degradation products, and the aniline was reused. One part of the degradation product was mixed with 30 parts of 1%wt lithium hydroxide solution and stirred at 100˚C for 20 min. After the reaction, bisphenol A was recovered by filtration.

[0099] In this embodiment, the degradation rate was 73.9%, and the bisphenol A recovery rate was 63.6%.

[0100] Example 38 First, one part of waste bisphenol A type polycarbonate was immersed in 17 parts of 1,4-butanediamine and stirred at 100˚C for 2 h. After the reaction, the degradation solution and solid residue were separated by filtration. Then, the degradation solution was distilled under reduced pressure to recover 1,4-butanediamine and the degradation product, and the 1,4-butanediamine was reused. One part of the degradation product was mixed with 13 parts of 5%wt ammonia solution and stirred at room temperature for 5 h. After the reaction, bisphenol A was recovered by filtration.

[0101] In this embodiment, the degradation rate was 95% and the bisphenol A recovery rate was 87.3%.

[0102] Example 39 Two parts of waste poly(p-hydroxybenzoate) were first immersed in 40 parts of 3-amino-1-propanol and stirred at 85˚C for 3 hours. After the reaction, the degradation solution and solid residue were separated by filtration. Then, the degradation solution was distilled under reduced pressure to recover 3-amino-1-propanol and the degradation product, and the 3-amino-1-propanol was reused. Two parts of the degradation product were mixed with 36 parts of 10%wt potassium carbonate solution and stirred at 50˚C for 4 hours. After the reaction, the pH of the filtrate was adjusted to acidic, and p-hydroxybenzoic acid was recovered by filtration.

[0103] In this embodiment, the degradation rate was 88.6%, and the recovery rate of p-hydroxybenzoic acid was 84.7%.

[0104] Example 40 Two parts of waste bisphenol A-terephthalic acid copolyester were first immersed in 14 parts of ethanolamine and reacted with stirring at 60˚C for 5 h. After the reaction, the degradation solution and solid residue were separated by filtration. The degradation solution was then distilled under reduced pressure to recover ethanolamine and degradation products, and the ethanolamine was reused. Two parts of the degradation product were mixed with 10 parts of 13%wt sodium carbonate solution and reacted with stirring at 80˚C for 2 h. After the reaction, bisphenol A was recovered by filtration, and the pH of the filtrate was adjusted to alkaline. The mixture of terephthalic acid and isophthalic acid was then recovered by filtration.

[0105] In this embodiment, the degradation rate was 94.8%, the bisphenol A recovery rate was 82%, and the recovery rate of the mixture of terephthalic acid and isophthalic acid was 84.3%.

Claims

1. A method for recycling waste polymer materials containing ester groups / amide bonds / imide bonds, characterized in that... The process steps and conditions of this method are as follows: 1) First, mix the waste polymer material containing ester group / amide bond / imide bond with organic amine at a mass ratio of 1:1 to 80, and then stir and react at room temperature to 140℃ for 20 min to 15 h; 2) After the reaction, the reaction reagents and degradation products are separated directly by distillation or vacuum distillation. The recovered organic amine can be reused. The recovered degradation product is mixed with an acid solution or an alkaline solution at a mass ratio of 1:1 to 30 and stirred at room temperature to 60°C for 10 min to 2 h. After the reaction, the monomer and filtrate are separated by filtration or distillation. The pH of the filtrate is then adjusted to alkaline or acidic, and another monomer can be recovered by filtration or distillation. The mass concentration of the acid solution is 1 to 10 wt%; the mass concentration of the alkaline solution is 1 to 10 wt%. The waste polymer material containing ester / amide / imide bonds mentioned above is at least one of waste polyimide, waste polycarbonate, waste polyester, and waste composite materials thereof. The organic amine mentioned therein is at least one selected from 3-amino-1-propanol, 2-amino-1-butanol, isopropanolamine, ethylenediamine, 1,4-butanediamine, 1,2-propanediamine, aniline, ethanolamine, diethanolamine, triethanolamine, and diethylenetriamine.

2. The method for recycling waste polymer materials containing ester groups / amide bonds / imide bonds according to claim 1, characterized in that... The acid solution mentioned in this method is any one of hydrochloric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid, propionic acid, butyric acid, or an aqueous solution of p-toluenesulfonic acid; the alkaline solution is any one of lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, cesium hydroxide, ammonia, sodium carbonate, or an aqueous solution of potassium carbonate.

3. The method for recycling waste polymer materials containing ester groups / amide bonds / imide bonds according to claim 1 or 2, characterized in that... In step 1) of this method, waste polymer materials containing ester groups / amide bonds / imide bonds are mixed with organic amines at a mass ratio of 1:1 to 30, and then reacted at room temperature to 140°C for 20 min to 5 h.

4. The method for recycling waste polymer materials containing ester groups / amide bonds / imide bonds according to claim 1 or 2, characterized in that... In step 1) of this method, waste polymer materials containing ester groups / amide bonds / imide bonds are mixed with organic amines at a mass ratio of 1:1 to 30, and then reacted at room temperature to 120°C for 20 min to 5 h.

Images