Degradable thioketal (aldehyde) epoxy resin curing agent as well as preparation method and application thereof

Abstract

The invention discloses a degradable thioketal (aldehyde) epoxy resin curing agent as well as a preparation method and application thereof, which can solve the problems of harsh degradation conditions, unadjustable degradation rate, poor thermal performance and the like of the existing epoxy resin material. The curing agent provided by the invention is simple in preparation method and low in toxicity, and can be prepared at a hectogram level or above; curing agents with different chemical structures can be obtained by replacing different reactants; the curing agent has various functional groups and can be further modified according to requirements; the degradation rate of the cured epoxy resin is adjustable, and the initial temperature of the curing reaction is diversified. Because thioketal has stable chemical properties, the cured epoxy resin has better thermal stability, thermal mechanical properties and acid-base stability than common degradable epoxy resin (Schiff base, ketal and the like), is equivalent to or even surpasses non-degradable epoxy resin, can be degraded in the presence of an oxidizing agent or metal ions, has unique degradation conditions, and is suitable for industrial production. A new thought is provided for epoxy resin degradation.

Description

Technical Field

[0001] This invention relates to a biodegradable thioketone (aldehyde)-based epoxy resin curing agent, its preparation method, and its application. This curing agent can be used to prepare biodegradable epoxy resins and their composite materials or adhesives, and belongs to the field of biodegradable epoxy resins. Background Technology

[0002] Epoxy resin is a traditional thermosetting polymer material. Due to its good mechanical properties, thermal properties, processability, chemical resistance and dimensional stability, it is widely used as a matrix polymer in the preparation of composite materials, coatings and adhesives.

[0003] In recent years, researchers have proposed many strategies for preparing biodegradable crosslinked epoxy resins. For example, epoxy resins cured with curing agents containing dynamic Schiff base bonds or ketal (aldehyde) bonds can degrade under acidic conditions; epoxy resins cured with curing agents containing disulfide bonds can degrade in the presence of dimercaptoethylene glycol. However, the degradation rate of epoxy resins cured with these biodegradable curing agents cannot be adjusted, and the curing temperature is relatively uniform. Furthermore, due to the presence of dynamic bonds in these curing agents, their thermomechanical properties are poor. Summary of the Invention

[0004] Based on the above analysis, this invention proposes a biodegradable thioketone (aldehyde)-based epoxy resin curing agent. These curing agents are simple to prepare, have low toxicity, and can easily achieve preparation in the hundreds of grams or larger. By changing different reactants, curing agents with different chemical structures can be obtained. The curing agents have diverse functional groups and can be further modified according to requirements, such as cyanate esterification and benzoxazineization. The cured epoxy resin exhibits superior thermal stability, thermomechanical properties, and acid-base stability compared to conventional biodegradable or dynamically bonded epoxy resins. The degradation rate of the epoxy resin is adjustable, and the curing reaction initiation temperature is diverse, resulting in excellent performance. Furthermore, this material can be degraded in the presence of oxidants or metal ions, enabling the recovery of some raw materials. The degraded resin contains a large number of hydroxyl groups and can still be used for downstream applications.

[0005] This invention discloses a biodegradable thiophene (aldehyde)-based epoxy resin curing agent, its preparation method, and its application. The general molecular structural formula of the curing agent is as follows: , R1 is , , , , , , , The presence of functional groups that can react with epoxy groups; If the curing agent is an acetal, one of the reactants is an aldehyde, and the chemical structures of R2 and R3 are hydrogen atoms (i.e., -H) and any of the structural combinations shown below: , , , wait; If the curing agent is a ketal, and one of the reactants is a ketone, the chemical structures of R2 and R3 are combined as follows: / , / wait; Compounds of this general structural formula can be used as curing agents in the preparation of biodegradable thiophene (aldehyde) epoxy resins.

[0006] The preparation method of the biodegradable thiophene (aldehyde) epoxy resin curing agent is as follows: Compound I and Compound II are mixed or dissolved in a reaction solvent and subjected to a nucleophilic addition reaction under the action of a catalyst to synthesize a biodegradable thioketone (aldehyde) epoxy resin curing agent; wherein the molar ratio of Compound I to Compound II is (0.1-10):1, and the reaction temperature is controlled at 0-80 ℃; wherein Compound I is a thiol compound; and the selected Compound II is a ketone compound or an aldehyde compound; the catalyst can be a Lewis acid, such as titanium tetrachloride, trifluoromethanesulfonic acid, p-toluenesulfonic acid, hydrochloric acid, sulfuric acid, trifluoroacetic acid, boron trifluoride, etc., and the amount used is 0.01-0.5 equivalents of the thiol compound.

[0007] The reaction solvent is one or a mixture of several of the following: water, methanol, ethanol, ethylene glycol, propanol, isopropanol, isopentane, pentane, petroleum ether, hexane, cyclohexane, cyclopentane, carbon tetrachloride, ethyl acetate, diethyl ether, isopropyl ether, tetrahydrofuran, chloroform, dioxane, benzene, toluene, dichloromethane, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0008] The thiol compounds may be compounds containing a thiol group, such as 4-aminothiophenol, 4-hydroxythiophenol, 4-mercaptobenzoic acid, 3-aminothiophenol, 3-hydroxythiophenol, 3-mercaptobenzoic acid, o-aminothiophenol, o-hydroxythiophenol, o-mercaptobenzoic acid, mercaptoacetic acid, mercaptoethanol, mercaptopropionic acid, cysteine ​​hydrochloride, cysteine, homocysteine ​​hydrochloride, etc. The ketone compounds may be acetone, butanone, etc.; the aldehyde compounds may be benzaldehyde, p-hydroxybenzaldehyde, vanillin, 3,4-dihydroxybenzaldehyde, etc.

[0009] The preparation method of the biodegradable thioketone (aldehyde) epoxy resin is as follows: the biodegradable thioketone (aldehyde) epoxy resin curing agent is mixed evenly with epoxy resin, and then a biodegradable thermosetting epoxy resin is generated by thermosetting crosslinking reaction, wherein the mass ratio of epoxy resin to curing agent is (0.1-10):1, and the curing reaction temperature is 0-200℃.

[0010] The epoxy resin is one or a mixture of several of the following: glycidyl amine epoxy resin, glycidyl ester epoxy resin, glycidyl ether epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, phenolic epoxy resin, cresolic epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, naphthalene-type epoxy resin, and biphenyl-type epoxy resin.

[0011] The biodegradable epoxy resin can be used in many fields such as adhesives and composite materials.

[0012] The adhesive is prepared from epoxy resin, biodegradable thioketone (aldehyde) epoxy resin curing agent and auxiliary materials.

[0013] The epoxy resin is one or a mixture of several of the following: glycidyl amine epoxy resin, glycidyl ester epoxy resin, glycidyl ether epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, phenolic epoxy resin, cresolic epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, naphthalene-type epoxy resin, and biphenyl-type epoxy resin; the auxiliary materials are one or more of the following: accelerator, toughening agent, thickener, plasticizer, diluent, coupling agent, defoamer, and stabilizer.

[0014] The composite material is prepared from epoxy resin, biodegradable thiophene (aldehyde) epoxy resin curing agent, reinforcement and auxiliary materials.

[0015] The epoxy resin is one or a mixture of several of the following: glycidyl amine epoxy resin, glycidyl ester epoxy resin, glycidyl ether epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, phenolic epoxy resin, cresolic epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, naphthalene-type epoxy resin, and biphenyl-type epoxy resin.

[0016] The reinforcing material is one or a mixture of several of the following: carbon fiber, glass fiber, aramid fiber, natural fiber, and nanoparticles (such as silicon dioxide, graphene, silicon nitride, and alumina).

[0017] The excipients are one or a mixture of several of the following: accelerators, toughening agents, thickeners, plasticizers, diluents, coupling agents, defoamers, stabilizers, leveling agents, antioxidants, brighteners, fluorescent reagents, pigments, and fillers.

[0018] The degradation method for the described biodegradable thioketone (aldehyde) epoxy resin, its composites, and adhesives is as follows: Under room temperature or heating conditions, an oxidant or metal salt is used, and a mixture of the oxidant and solvent is used as the degradation solution. Under stirring conditions, the degradation of the biodegradable thioketone (aldehyde) epoxy resin, its composites, and adhesives is achieved. The molar concentration of the oxidant or metal salt is 0.1-20 M; the heating temperature is 0-200℃; and the reaction time is 0.01-21 days.

[0019] The oxidant is hydrogen peroxide, m-chloroperoxybenzoic acid, peracetic acid, peroxytert-butanol, potassium persulfate, potassium permanganate, nitric acid, etc., with hydrogen peroxide being preferred; the metal salt is copper chloride, copper sulfate, copper nitrate, silver nitrate, cerium nitrate, ferric chloride, etc. The solvent is one or a mixture of several of the following: water, methanol, ethanol, ethylene glycol, propanol, isopropanol, isopentane, pentane, petroleum ether, hexane, cyclohexane, cyclopentane, carbon tetrachloride, ethyl acetate, diethyl ether, isopropyl ether, tetrahydrofuran, chloroform, dioxane, benzene, toluene, dichloromethane, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0020] Benefits of this invention: The epoxy resin cured by the above-mentioned thioketone curing agent in this invention has excellent acid and alkali stability compared with the biodegradable epoxy resin or dynamic bond epoxy resin currently studied, and its thermomechanical properties (such as stress relaxation and creep) are significantly improved compared with common epoxy resins. The degradation method of the cured epoxy resin is novel and can be degraded in the presence of hydrogen peroxide, which is green and environmentally friendly. The degradation products contain a large number of polar groups such as sulfonic acid groups, which can be recycled and used in adhesives. Attached Figure Description

[0021] Figure 1 The 1H NMR spectrum of the biodegradable thioketone (aldehyde) epoxy resin curing agent prepared in Example 1 of this invention.

[0022] Figure 2 The 1H NMR spectrum of the biodegradable thioketone (aldehyde) epoxy resin curing agent prepared in Example 2 of this invention.

[0023] Figure 3 The 1H NMR spectrum of the biodegradable thioketone (aldehyde) epoxy resin curing agent prepared in Example 3 of this invention.

[0024] Figure 4 The 1H NMR spectrum of the biodegradable thioketone (aldehyde) epoxy resin curing agent prepared in Example 4 of this invention.

[0025] Figure 5The 1H NMR spectrum of the biodegradable thioketone (aldehyde) epoxy resin curing agent prepared in Example 5 of this invention.

[0026] Figure 6 The flexural strength of the biodegradable composite material prepared in Example 10 of the present invention.

[0027] Figure 7 The bonding strength of the biodegradable adhesive prepared in Example 11 of this invention to the aluminum sheet. Detailed Implementation

[0028] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] Example 1 A biodegradable thiophene (aldehyde)-based epoxy resin curing agent, the molecular formula of which is: (TK) The preparation method of this biodegradable thiophene (aldehyde) epoxy resin curing agent is as follows: 113.61 g of cysteine ​​hydrochloride was fully dissolved in 200 mL of organic acid solution. 0.1 mL of trifluoroacetic acid and 50 mL of acetone were added, and the mixture was stirred for 3 hours, resulting in a white precipitate. After filtration, the curing agent hydrochloride was obtained. The hydrochloride was then placed in 250 mL of 12M saturated sodium hydroxide solution, and the oily liquid was separated. After drying, curing agent TK was obtained. The 1H NMR spectrum is shown below. Figure 1 As shown.

[0030] Example 2 A biodegradable thiophene (aldehyde)-based epoxy resin curing agent, the molecular formula of which is: (ArTKNH2) The preparation method of this biodegradable thiophene (aldehyde) epoxy resin curing agent is as follows: 125.19 g of 4-aminobenzylthiophenol was fully dissolved in 120 mL of acetone solution, and 150 mL of concentrated hydrochloric acid was added. After reacting overnight, the reaction solution was poured into 1 L of 4M sodium hydroxide solution and filtered to obtain the curing agent. The product was washed with a small amount of methanol to obtain the curing agent ArTKNH2. The 1H NMR spectrum is shown below. Figure 2 As shown.

[0031] Example 3 A biodegradable thiophene (aldehyde)-based epoxy resin curing agent, the molecular formula of which is: (ArTKOH) The preparation method of this biodegradable thiophene (aldehyde) epoxy resin curing agent is as follows: 126.18 g of 4-hydroxybenzylthiophenol was fully dissolved in 100 mL of methanol solution. 0.5 g of p-toluenesulfonic acid (TsOH) and 61.0 g of p-hydroxybenzaldehyde were added. After reacting overnight, the reaction solution was poured into 1 L of 2M sodium bicarbonate solution and filtered to obtain the crude product. The crude product was purified by recrystallization. The crude product was dissolved in methanol and precipitated in sodium bicarbonate solution. After filtration and drying, pure curing agent ArTKOH was obtained. The 1H NMR spectrum is shown below. Figure 3 As shown.

[0032] Example 4 A biodegradable thiophene (aldehyde)-based epoxy resin curing agent, the molecular formula of which is:

[0033] The preparation method of this biodegradable thiophene (aldehyde) epoxy resin curing agent is as follows: 126.18 g of 4-hydroxythiophenol was fully dissolved in 60 mL of acetone solution, and 0.5 g of TsOH was added. After reacting overnight, the reaction solution was poured into 1 L of 2M sodium bicarbonate solution and filtered to obtain the crude product. The crude product was purified by recrystallization. The crude product was dissolved in acetone and precipitated in sodium bicarbonate solution. After filtration and drying, the curing agent was obtained. The 1H NMR spectrum is shown below. Figure 4 As shown.

[0034] Example 5 A biodegradable thiophene (aldehyde)-based epoxy resin curing agent, the molecular formula of which is:

[0035] The preparation method of this biodegradable thiophene (aldehyde) epoxy resin curing agent is as follows: 92.12 g of mercaptoacetic acid and 69.06 g of 3,4-dihydroxybenzaldehyde were mixed and refluxed at 80 °C. The solid was washed several times with dichloromethane, filtered, and dried to obtain the curing agent. The 1H NMR spectrum is shown below. Figure 5 As shown.

[0036] Example 6 The preparation of biodegradable thiophene (aldehyde) epoxy resin is as follows: After mixing 2.48 g of curing agent TK from Example 1 and 10.00 g of E51 evenly, the mixture was poured into a tetrafluoroethylene mold and degassed at 60°C for 5 min. The mixture was then heated to 80°C for 2 h and cured at 120°C for 2 h to obtain the biodegradable epoxy resin material TK / E51.

[0037] Example 7 The preparation of biodegradable thiophene (aldehyde) epoxy resin is as follows: After mixing 3.70 g of curing agent ArTKNH2 and 10.00 g of E51 from Example 2 at 90°C, the mixture was poured into a tetrafluoroethylene mold and degassed at 110°C for 5 min. The mixture was then heated to 130°C for 2 h and finally cured at 160°C for 4 h to obtain the biodegradable epoxy resin material ArTKNH2 / E51.

[0038] Example 8 The preparation of biodegradable thiophene (aldehyde) epoxy resin is as follows: Dissolve 6.06 g of the curing agent ArTKOH from Example 3, 10.00 g of E51, and 0.06 g of 2-methylimidazole in 5 mL of acetone solution and stir until homogeneous. Pour the solution into a tetrafluoroethylene mold and degas at 100°C for 15 min. Then, heat to 130°C and cure for 2 h, followed by vacuum curing at 160°C for 4 h to obtain the biodegradable epoxy resin material ArTKOH / E51. The properties of the epoxy resins in Examples 6-8 are summarized in Table 1. The obtained epoxy resins exhibit good mechanical and thermal properties.

[0039] Table 1. Properties of the biodegradable epoxy resins prepared in Examples 6-8

[0040] Example 9 The preparation of biodegradable thiophene (aldehyde) epoxy resin is as follows: After mixing 5.11 g of curing agent ArTKNH2 from Example 2 and 10.00 g of naphthalene-type epoxy resin HP4032D (142 g / eq) at 90°C, the mixture was poured into a tetrafluoroethylene mold and degassed at 90°C for 5 min. The mixture was then heated to 130°C for 2 h and cured at 160°C for 4 h to obtain the biodegradable epoxy resin material ArTKNH2 / HP4032D.

[0041] Example 10 Preparation of biodegradable epoxy resin glass fiber composite materials 7.4 g of the curing agent ArTKNH2 from Example 2 and 20.00 g of E51 were dissolved in acetone. The solution was coated onto glass fiber cloth to prepare a prepreg. Ten layers of prepreg were stacked on top of each other and cured using a flat vulcanizing machine at a pressure of 10 MPa. The preheating temperature was 110°C for 20 min, then increased to 130°C for 2 h, and finally increased to 160°C for 4 h to obtain a biodegradable epoxy resin glass fiber composite material. Figure 6 As shown, the flexural strength of the composite material is 511.5 MPa, which is similar to the performance of common glass fiber reinforced composite materials.

[0042] Example 11 Preparation of biodegradable epoxy resin adhesives After mixing 2.48 g of curing agent TK from Example 1 and 10.00 g of E51 thoroughly, an epoxy resin adhesive was obtained. Its bonding strength to the aluminum sheet was measured to be 5.57 MPa. Figure 7 .

[0043] Example 12 Preparation of biodegradable epoxy resin adhesives Mix 10.00 g of E51 and 20 g of silver powder evenly, then add 2.48 g of curing agent TK from Example 1, and stir evenly to obtain conductive epoxy resin adhesive.

[0044] Example 13 Degradation of biodegradable epoxy resin materials in oxidants A degradation solution was prepared by mixing 3 mL of 30% hydrogen peroxide solution and 12 mL of tetrahydrofuran. 1 g of the epoxy resin obtained in Example 6 was immersed in the degradation solution and heated at 50°C for 3 days, resulting in complete degradation of the epoxy resin. The organic solvent was removed by rotary evaporation of the degraded solution, and then the solution was dried. The obtained degradation product was dissolved in DMF (1 g / mL) to obtain the regenerated adhesive.

[0045] Example 14 Degradation of biodegradable epoxy resin materials in oxidants A degradation solution was prepared by mixing 3 mL of 30% hydrogen peroxide solution and 12 mL of tetrahydrofuran. 1 g of the epoxy resin obtained in Example 7 was immersed in the degradation solution and heated at 50°C for 7 days, after which the epoxy resin was completely degraded.

[0046] Example 15 Degradation of biodegradable epoxy resin materials in oxidants A degradation solution was prepared by mixing 3 mL of 30% hydrogen peroxide solution and 12 mL of tetrahydrofuran. 1 g of the epoxy resin obtained in Example 8 was immersed in the degradation solution and heated at 50°C for 1.5 days, after which the epoxy resin was completely degraded.

[0047] Example 16 Degradation of biodegradable epoxy resin materials in metal salts 2.56 g of copper chloride dihydrate was dissolved in 15 mL of N,N-dimethylformamide solvent to prepare a degradation solution. 1 g of the epoxy resin obtained in Example 8 was immersed in the degradation solution and heated at 110 °C for 18 h, after which the epoxy resin was completely degraded.

[0048] Example 17 Degradation and recycling of biodegradable epoxy resin glass fiber composites 1g of the biodegradable epoxy resin glass fiber composite material prepared in Example 10 was placed in a glass bottle, and 3mL of hydrogen peroxide and 12mL of tetrahydrofuran solvent were added to it for degradation at 50°C. After the composite material was completely degraded, it was filtered and the glass fiber was recovered.

[0049] The embodiments described above are merely some preferred embodiments of the present invention, and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A biodegradable thiophene (aldehyde)-based epoxy resin curing agent, characterized in that, The general molecular formula of this curing agent is: , R1 is , , , , , , or ; If the curing agent is an acetal, the chemical structures of R2 and R3 are combinations of -H and any of the structures shown below: ， ， ， ； If the curing agent is a ketal, the chemical structures of R2 and R3 are combined as follows: / ， / 。 2. The preparation method of the biodegradable thioketone (aldehyde) epoxy resin curing agent as described in claim 1, characterized in that, Including the following: Compound I and Compound II are mixed or dissolved in a solvent and subjected to a nucleophilic addition reaction under the action of a catalyst to synthesize a biodegradable thioketone (aldehyde) type epoxy resin curing agent; The molar ratio of compound I to compound II is (0.1-10):1, and the reaction temperature is controlled at 0-80 ℃. The selected compound I is a thiol compound, and the selected compound II is a ketone compound or an aldehyde compound.

3. The method for preparing the biodegradable thioketone (aldehyde) epoxy resin curing agent according to claim 2, characterized in that: The solvent is one or a mixture of several of the following: water, methanol, ethanol, ethylene glycol, propanol, isopropanol, isopentane, pentane, petroleum ether, hexane, cyclohexane, cyclopentane, carbon tetrachloride, ethyl acetate, diethyl ether, isopropyl ether, tetrahydrofuran, chloroform, dioxane, benzene, toluene, dichloromethane, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

4. The method for preparing the biodegradable thioketone (aldehyde) epoxy resin curing agent according to claim 2, characterized in that: The thiols are selected from 4-aminobenzylthiophenol, 4-hydroxybenzylthiophenol, 4-mercaptobenzoic acid, 3-aminobenzylthiophenol, 3-hydroxybenzylthiophenol, 3-mercaptobenzoic acid, o-aminobenzylthiophenol, o-hydroxybenzylthiophenol, o-mercaptobenzoic acid, mercaptoethanol, mercaptopropionic acid, cysteine ​​hydrochloride, cysteine, homocysteine ​​hydrochloride; the ketones are selected from acetone and butanone; the aldehydes are selected from benzaldehyde, p-hydroxybenzaldehyde, vanillin, and 3,4-dihydroxybenzaldehyde.

5. A biodegradable thioketone (aldehyde) epoxy resin, characterized in that, The epoxy resin is prepared as follows: The biodegradable thioketone (aldehyde) epoxy resin curing agent according to claim 1 is mixed evenly with epoxy resin, and then a biodegradable thioketone (aldehyde) epoxy resin is generated by thermosetting crosslinking reaction, wherein the mass ratio of epoxy resin to curing agent is (0.1-10):1, and the curing reaction temperature is 0-200℃.

6. The biodegradable thioketone (aldehyde) epoxy resin according to claim 5, characterized in that: The epoxy resin is one or a mixture of several of the following: glycidyl amine type epoxy resin, glycidyl ester type epoxy resin, glycidyl ether type epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, phenolic aldehyde type epoxy resin, cresol aldehyde type epoxy resin, aliphatic epoxy resin, naphthalene type epoxy resin, and biphenyl type epoxy resin.

7. A biodegradable thiophene (aldehyde)-based epoxy resin adhesive, characterized in that: The adhesive is prepared from epoxy resin, the biodegradable thioketone (aldehyde) epoxy resin curing agent as described in claim 1, and auxiliary materials; The epoxy resin is one or a mixture of several of the following: glycidyl amine epoxy resin, glycidyl ester epoxy resin, glycidyl ether epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, phenolic epoxy resin, cresolic epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, naphthalene epoxy resin, and biphenyl epoxy resin. The auxiliary materials are one or a mixture of several of the following: accelerators, toughening agents, thickeners, plasticizers, diluents, coupling agents, defoamers, stabilizers, leveling agents, antioxidants, brighteners, fluorescent reagents, pigments, and fillers.

8. A biodegradable thiophene (aldehyde)-based epoxy resin composite material, characterized in that: The composite material is prepared from epoxy resin, the biodegradable thioketone (aldehyde) epoxy resin curing agent as described in claim 1, fiber reinforcement, and auxiliary materials; The epoxy resin is one or a mixture of several of the following: glycidyl amine epoxy resin, glycidyl ester epoxy resin, glycidyl ether epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, phenolic epoxy resin, cresolic epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, naphthalene epoxy resin, and biphenyl epoxy resin. The fiber reinforcement is one or a mixture of several of the following: carbon fiber, glass fiber, aramid fiber, natural fiber, and nanoparticles. The auxiliary materials are one or a mixture of several of the following: accelerators, toughening agents, thickeners, plasticizers, diluents, coupling agents, defoamers, stabilizers, leveling agents, antioxidants, brighteners, fluorescent reagents, pigments, and fillers.

9. The degradation method of the epoxy resin as claimed in claim 5, the adhesive as claimed in claim 7, or the composite material as claimed in claim 8, characterized in that, Including the following: Under room temperature or heating conditions, an oxidant or metal salt is used to form a mixture with a solvent as a degradation solution, which is then added to the sample to be degraded. Under stirring conditions, the degradation of the sample is achieved. The molar concentration of the oxidant or metal salt is 0.1-20 M; The heating temperature is 0-200℃; the reaction time is 0.01-21 days.

10. The degradation method according to claim 9, characterized in that: The oxidant is selected from hydrogen peroxide, m-chloroperoxybenzoic acid, peracetic acid, peroxytert-butanol, potassium persulfate, potassium permanganate, and nitric acid, preferably hydrogen peroxide; the metal salt is selected from copper chloride, copper sulfate, copper nitrate, silver nitrate, cerium nitrate, and ferric chloride. The solvent is one or a mixture of several of the following: water, methanol, ethanol, ethylene glycol, propanol, isopropanol, isopentane, pentane, petroleum ether, hexane, cyclohexane, cyclopentane, carbon tetrachloride, ethyl acetate, diethyl ether, isopropyl ether, tetrahydrofuran, chloroform, dioxane, benzene, toluene, dichloromethane, acetone, acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

Images