A method for efficient degradation and recovery of waste epoxy resin and composite materials thereof by metal-functionalized ionic liquid catalysis

Abstract

The application discloses a method for efficiently degrading and recycling waste epoxy resin and a composite material thereof by using a metal-functionalized ionic liquid, and belongs to the technical field of waste epoxy resin degradation and recycling. The method is characterized by mixing waste epoxy resin material or waste epoxy resin composite material with a catalytic degradation solution at a mass ratio of 1:1-10, heating and refluxing under nitrogen protection at 60-120 DEG C, and reacting for 1-36 hours until the resin disappears completely and degradation is completed. The waste epoxy resin material contains ester functional groups in its structure, including ester groups at crosslinking points or ester groups in the bulk. In the application, the central metal atom of the metal-functionalized ionic liquid is coordinated with atoms in the waste epoxy resin and the degradation solution, so that the degradation solution can be enriched on the surface of the resin, greatly accelerating the erosion of the degradation solution on the surface of the epoxy resin, making the degradation solution more easily enter the resin system, and thus more quickly collapsing the crosslinked network, and greatly accelerating the degradation efficiency.

Description

Technical Field

[0001] This invention belongs to the field of waste epoxy resin degradation and recycling technology, and particularly relates to the degradation technology of waste epoxy resin catalyzed by metal-functionalized ionic liquid. It utilizes metal-functionalized ionic liquid to catalyze and assist in the degradation of waste epoxy resin and its composite materials. The final degradation products can be used as curing agents for the curing of epoxy resin, realizing the full recycling and reuse of waste epoxy resin. Background Technology

[0002] Epoxy resin is a common thermosetting material widely used in coatings, adhesives, building materials, and other engineering fields. Using a curing agent, low-molecular-weight epoxy monomers undergo a cross-linking reaction, producing thermosetting epoxy resins with a three-dimensional (3D) network structure. It is this 3D cross-linked network structure that endows epoxy resins with a series of advantages, such as excellent mechanical strength, dielectric properties, heat resistance, and chemical resistance. However, it is also its irreversible 3D cross-linked network structure that makes epoxy resins infusible and insoluble thermosetting materials. This presents a significant challenge to the degradation and recycling of epoxy resins in waste electrical and electronic equipment. Rapid industrial development has led to a year-on-year increase in the use of epoxy resins, resulting in a growing amount of waste epoxy resins, causing significant environmental pollution and resource waste. Therefore, achieving their effective recycling and reuse is of great importance for environmental protection and resource conservation.

[0003] Anhydride-cured epoxy resins are widely used in high-performance fields such as electronic packaging and composite materials due to their good heat resistance and high strength. Therefore, degrading and recycling anhydride-cured epoxy resins not only creates secondary value through resin reuse, but more importantly, it allows for the recovery of high-value products such as rare metals or reinforcing fibers. Existing patents on the degradation of anhydride-cured epoxy resins, such as CN119119424A, disclose a method for degrading, recycling, and reusing anhydride-cured epoxy resin fiber-reinforced composite materials. This method utilizes alkali-catalyzed ester hydrolysis to degrade epoxy resins and obtain polyol products. However, polyols are difficult to further reuse and can only be used as additives in epoxy resins, with limited effectiveness. Furthermore, they require the addition of acid solutions to generate carboxylic acid intermediates for further processing, making the operation complex and difficult to apply later. For example, CN119528716A discloses a phase transfer separation method for degradation products of anhydride-cured epoxy resin. This method utilizes a mixed solution of ethylene glycol and sodium hydroxide to degrade the ester groups, separating the degradation products to obtain glycidyl ether and anhydride, which can be further synthesized into epoxy resin. However, the reaction consumes large amounts of alkali and alcohol, and complete degradation is not possible. Similarly, CN118005993B discloses a composition for degrading anhydride-cured epoxy resin and a method for degrading regenerated anhydride-cured epoxy resin. This method utilizes benzoxazine and a strong alkaline aqueous solution to degrade the ester groups, but the degradation products require further reaction before reuse. In summary, finding a mild, simple degradation method and a smooth and effective reprocessing method for anhydride-cured epoxy resin is of great significance. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a highly efficient method for the degradation and recycling of waste epoxy resin and its composite materials using a metal-functionalized ionic liquid catalyst. The catalyst used in this invention can rapidly degrade epoxy resin at a suitable temperature, and the resulting degradation products can be efficiently reused for the curing of epoxy resin. Epoxy resin cured based on these degradation products exhibits superior performance and higher strength than the original epoxy resin. This invention offers significant environmental advantages for the recycling and reuse of thermosetting epoxy resin-based composite materials.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A highly efficient degradation and recycling method for waste epoxy resin and its composite materials catalyzed by metal-functionalized ionic liquid is disclosed. The method comprises: mixing waste epoxy resin material or waste epoxy resin composite material with a catalytic degradation liquid at a mass ratio of 1:1-10, heating and refluxing under nitrogen protection at 60-120℃, and reacting for 1-36 hours until the resin is completely destroyed and degradation is completed. The resulting degradation product can be directly used as a curing agent for epoxy resin.

[0007] Furthermore, the structure of the waste epoxy resin material contains ester functional groups, including ester groups at the crosslinking points, such as epoxy resin cured with anhydride curing agents; or ester groups in the bulk, such as epoxy resin cured with glycidyl ester epoxy resin.

[0008] Furthermore, the waste epoxy resin composite material is prepared from epoxy resin, reinforcement, and auxiliary materials; the epoxy resin contains ester functional groups in its structure, including ester groups at the crosslinking points, such as epoxy resin cured with anhydride curing agents; or contains ester groups in its bulk, such as epoxy resin cured with glycidyl ester epoxy resin; the reinforcement is a fiber material or nanomaterial; the auxiliary materials include at least one of accelerators, diluents, plasticizers, toughening agents, thickeners, coupling agents, defoamers, leveling agents, ultraviolet absorbers, antioxidants, brighteners, fluorescent reagents, pigments, and fillers.

[0009] Furthermore, the fiber material is one or more of carbon fiber, glass fiber, natural fiber, chemical fiber, or fabric made from the aforementioned fiber materials; the nanomaterial is one or more of carbon nanomaterials, boron nitride nanomaterials, metal nanoparticles, metal oxide nanoparticles, or organic nanoparticles.

[0010] Furthermore, the catalytic degradation solution is composed of a metal-functionalized ionic liquid and an amine degradation solution; the metal-functionalized ionic liquid is composed of cations, anions, and a central metal atom; the cations include one of 1-methylimidazolium, tetraethylammonium, tetrabutylammonium, ethyltriethylaminealkyltributylammonium, butyltriethylaminealkyltributylammonium, and diethylenetriamine; the anions include one of chlorine, bromine, tetrafluoroboric acid, hexafluorophosphate, trifluoroacetic acid, trifluoromethanesulfonic acid, and acetic acid; the central metal atom is one or more of Cu, Pd, Cd, Zn, Cr, Ni, Al, Mn, and Co; the amine degradation solution is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,3-diaminocyclohexane, isophorone diamine, diaminocyclohexane, m-phenylenediamine, m-phenylenediamine, and diaminodiphenylmethane.

[0011] Furthermore, the mass percentage of the metal-functionalized ionic liquid in the catalytic degradation solution is 1-30%; the mass percentage of the degradation solution in the catalytic degradation solution is 70-99%.

[0012] The advantages of this invention compared to existing technologies are as follows: This invention successfully degrades waste epoxy resin using a highly efficient catalytic method utilizing metal-functionalized ionic liquids, achieving efficient degradation of waste epoxy resin. By coordinating the central metal atoms of the metal-functionalized ionic liquid with atoms in the waste epoxy resin and the degradation solution, the degradation solution can accumulate on the resin surface, greatly accelerating the erosion of the epoxy resin surface by the degradation solution. This allows the degradation solution to more easily enter the resin system, thereby more quickly disintegrating the cross-linked network and significantly accelerating the degradation efficiency. Furthermore, the central metal atoms of the metal-functionalized ionic liquid activate the ester groups contained in the waste epoxy resin, making them more easily attacked and decomposed. Moreover, the cations in the ionic liquid can enhance the toughness of the epoxy resin, so that when the epoxy resin obtained after degradation is re-cured, the tensile strength of the resulting epoxy resin is even better than that of the original resin. This achieves 100% recycling and 100% reuse of waste epoxy resin, which is highly beneficial to the environment, achieves negative carbon emissions, and creates secondary value for waste epoxy resin waste. Detailed Implementation

[0013] The technical solution of the present invention will be further described below with reference to the embodiments, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0014] Example 1:

[0015] Waste epoxy resin and catalytic degradation solution (diethylenetriamine: [BmimCl][MnCl2] = 90:10) were mixed at a mass ratio of 1:5 and placed in a reaction flask. The mixture was refluxed under nitrogen protection and heated to 80°C for 8 hours. All solids disappeared, and a homogeneous solution was finally obtained.

[0016] The degradation products were directly mixed with epoxy resin E-51 and cured at 80°C for 2 hours to produce new epoxy resin for reuse. The epoxy resin obtained from the reuse of degradation products can achieve a tensile strength of up to 65 MPa and an elongation at break of up to 4.2%.

[0017] Example 2:

[0018] Waste epoxy resin and catalytic degradation solution (diethylenetriamine: [(DETA)OAc][Co(OAc)2] = 95:5) were mixed at a mass ratio of 1:1 and placed in a reaction flask. The mixture was refluxed under nitrogen protection and heated to 60°C for 10 hours. All solids disappeared, and a homogeneous solution was finally obtained.

[0019] The degradation products were directly mixed with epoxy resin E-51 and cured at 80°C for 2 hours to produce new epoxy resin for reuse. The epoxy resin obtained from the reuse of degradation products can achieve a tensile strength of up to 68 MPa and an elongation at break of up to 4.3%.

[0020] Example 3:

[0021] Waste epoxy resin and catalytic degradation solution (triethylenetetramine: [BmimCl][CuCl2] = 85:15) were mixed at a mass ratio of 1:3 and placed in a reaction flask. The mixture was refluxed under nitrogen protection and heated to 80°C for 8 hours. All solids disappeared, and a homogeneous solution was finally obtained.

[0022] The degradation products were directly mixed with epoxy resin E-51 and cured at 80°C for 2 hours to produce new epoxy resin for reuse. The epoxy resin obtained from the reuse of degradation products can achieve a tensile strength of up to 67 MPa and an elongation at break of up to 4.3%.

[0023] Example 4:

[0024] Waste epoxy resin and catalytic degradation solution (1,3-diaminocyclohexane: [EmimCl][NiCl2] = 70:30) were mixed at a mass ratio of 1:3 and placed in a reaction flask. The mixture was refluxed under nitrogen protection and heated to 100°C for 10 hours. All solids disappeared, and a homogeneous solution was finally obtained.

[0025] The degradation products were directly mixed with epoxy resin E-51 and cured at 80°C for 2 hours to produce new epoxy resin for reuse. The epoxy resin obtained from the reuse of degradation products can achieve a tensile strength of up to 72 MPa and an elongation at break of up to 4.5%.

[0026] Example 5:

[0027] Waste epoxy resin and catalytic degradation solution (m-phenylenediamine: [EmimCl][CoCl2] = 75:25) were mixed at a mass ratio of 1:10 and placed in a reaction flask. The mixture was refluxed under nitrogen protection and heated to 120°C for 8 hours. All solids disappeared, and a homogeneous solution was finally obtained.

[0028] The degradation products were directly mixed with epoxy resin E-51 and cured at 80°C for 2 hours to produce new epoxy resin for reuse. The epoxy resin obtained from this recycled degradation process can achieve a tensile strength of up to 75 MPa and an elongation at break of up to 4.5%.

[0029] Example 6:

[0030] Waste epoxy resin and catalytic degradation solution (m-phenylenediamine: [PmimCl][MnCl2] = 80:20) were mixed at a mass ratio of 1:10 and placed in a reaction flask. The mixture was refluxed under nitrogen protection and heated to 150°C for 8 hours. All solids disappeared, and a homogeneous solution was finally obtained.

[0031] The degradation products were directly mixed with epoxy resin E-51 and cured at 80°C for 2 hours to produce new epoxy resin for reuse. The epoxy resin obtained from the reuse of degradation products can achieve a tensile strength of up to 81 MPa and an elongation at break of up to 5.1%.

[0032] Example 7:

[0033] Waste epoxy resin and catalytic degradation solution (isophorone diamine: [PmimCl][CuCl2] = 90:10) were mixed at a mass ratio of 1:10 and placed in a reaction flask. The mixture was refluxed under nitrogen protection and heated to 150°C for 12 hours. All solids disappeared, and a homogeneous solution was finally obtained.

[0034] The degradation products were directly mixed with epoxy resin E-51 and cured at 80°C for 2 hours to produce new epoxy resin for reuse. The epoxy resin obtained from this recycled degradation process can achieve a tensile strength of up to 75 MPa and an elongation at break of up to 4.6%.

[0035] Example 8:

[0036] Waste epoxy resin and catalytic degradation solution (diaminodiphenylmethane: [RmimCl][NiCl2] = 90:10) were mixed at a mass ratio of 1:8 and placed in a reaction flask. The mixture was refluxed under nitrogen protection and heated to 150°C for 16 hours. All solids disappeared, and a homogeneous solution was finally obtained.

[0037] The degradation products were directly mixed with epoxy resin E-51 and cured at 80°C for 2 hours to produce new epoxy resin for reuse. The epoxy resin obtained from the reuse of degradation products can achieve a tensile strength of up to 84 MPa and an elongation at break of up to 5.3%.

[0038] Example 9:

[0039] Waste epoxy resin and catalytic degradation solution (diethylenetriamine: [(DETA)OAc][Ni(OAc)2] = 95:5) were mixed in a 1:1 mass ratio and placed in a reaction flask. The mixture was refluxed under nitrogen protection and heated to 60°C for 10 hours. All solids disappeared, and a homogeneous solution was finally obtained.

[0040] The degradation products were directly mixed with epoxy resin E-51 and cured at 80°C for 2 hours to produce new epoxy resin for reuse. The epoxy resin obtained from the reuse of degradation products can achieve a tensile strength of up to 66 MPa and an elongation at break of up to 4.2%.

[0041] Example 10:

[0042] Waste epoxy resin-reinforced carbon fiber composite material was mixed with a catalytic degradation solution (diethylenetriamine: [(DETA)OAc][Cu(OAc)2] = 80:20) at a mass ratio of 1:3 in a reaction flask. The mixture was refluxed under nitrogen protection and heated to 80°C for 15 hours. The resin on the carbon fiber surface completely dissolved, exposing the entire carbon fiber. After rinsing with dichloromethane and drying, clean carbon fiber bundles were obtained. The tensile strength of each filament was measured, showing a strength retention rate of 92%, indicating that the degraded fibers still maintained good strength.

[0043] The degradation products were directly mixed with epoxy resin E-51 and cured at 80°C for 2 hours to produce new epoxy resin for reuse. The epoxy resin obtained from the reuse of degradation products can achieve a tensile strength of up to 63 MPa and an elongation at break of up to 4.0%.

[0044] Example 11:

[0045] Waste epoxy resin glass fiber reinforced composite material was mixed with a catalytic degradation solution (1,3-diaminocyclohexane: [PmimBr][NiBr2] = 90:10) at a mass ratio of 1:5 in a reaction flask. The mixture was refluxed under nitrogen protection and heated to 100℃ for 24 hours. The resin on the glass fiber surface was completely dissolved, exposing the glass fibers. After rinsing with dichloromethane and drying, clean glass fiber bundles were obtained. The tensile strength of each filament was measured, showing a strength retention rate of 94%, indicating that the degraded fibers still retained good strength.

[0046] The degradation products were directly mixed with epoxy resin E-51 and cured at 80°C for 2 hours to produce new epoxy resin for reuse. The epoxy resin obtained from the reuse of degradation products can achieve a tensile strength of up to 66 MPa and an elongation at break of up to 4.2%.

Claims

1. A highly efficient method for the degradation and recycling of waste epoxy resin and its composite materials catalyzed by metal-functionalized ionic liquids, characterized in that: The method involves mixing waste epoxy resin material or waste epoxy resin composite material with a catalytic degradation solution at a mass ratio of 1:1 to 10, heating under nitrogen protection at 60 to 120°C for 1 to 36 hours until the resin is completely destroyed and degradation is complete. The catalytic degradation solution consists of a metal-functionalized ionic liquid and an amine degradation solution. The metal-functionalized ionic liquid is composed of cations, anions, and a central metal atom. The cations include 1-methylimidazole, tetraethylammonium, tetrabutylammonium, ethyltriethylaminealkyltributylammonium, and butyltriethylamine. The amine is selected from alkyltributylammonium and diethylenetriamine; the anion includes chlorine, bromine, tetrafluoroboric acid, hexafluorophosphate, trifluoroacetic acid, trifluoromethanesulfonic acid, and acetic acid; the central metal atom is one or more of Cu, Pd, Cd, Zn, Cr, Ni, Al, Mn, and Co; the amine degradation solution is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,3-diaminocyclohexane, isophorone diamine, diaminocyclohexane, m-phenylenediamine, m-phenylenediamine, and diaminodiphenylmethane.

2. The efficient degradation and recycling method for waste epoxy resin and its composite materials catalyzed by metal-functionalized ionic liquid according to claim 1, characterized in that: The waste epoxy resin material contains ester functional groups in its structure, including ester groups at crosslinking points or ester groups in the bulk.

3. The efficient degradation and recycling method for waste epoxy resin and its composite materials catalyzed by metal-functionalized ionic liquid according to claim 1, characterized in that: The waste epoxy resin composite material is prepared from epoxy resin, reinforcement, and auxiliary materials; the epoxy resin contains ester functional groups in its structure, including ester groups at crosslinking points or ester groups in the bulk; the reinforcement is a fiber material or nanomaterial; the auxiliary materials include at least one of the following: accelerator, diluent, plasticizer, toughening agent, thickener, coupling agent, defoamer, leveling agent, ultraviolet absorber, antioxidant, brightener, fluorescent reagent, pigment, and filler.

4. The efficient degradation and recycling method for waste epoxy resin and its composite materials catalyzed by metal-functionalized ionic liquid according to claim 3, characterized in that: The fiber material is one or more of carbon fiber, glass fiber, natural fiber, chemical fiber, or fabric made from the aforementioned fiber materials; the nanomaterial is one or more of carbon nanomaterials, boron nitride nanomaterials, metal nanoparticles, metal oxide nanoparticles, or organic nanoparticles.

5. The efficient degradation and recycling method for waste epoxy resin and its composite materials catalyzed by metal-functionalized ionic liquid according to claim 1, characterized in that: The mass percentage of the metal-functionalized ionic liquid in the catalytic degradation solution is 1-30%; the mass percentage of the degradation solution in the catalytic degradation solution is 70-99%.