A method for degradation, recycling, and reuse of anhydride-cured epoxy resin

Abstract

This invention discloses a method for the degradation, recycling, and reuse of anhydride-cured epoxy resin, relating to the field of epoxy resin and its degradation and regeneration. This invention provides a method for catalytically degrading anhydride-cured epoxy resin, which achieves rapid and efficient degradation of epoxy resin under mild conditions. The generated degradation products contain active groups and can be further recycled. This invention also provides a method for regenerating anhydride-cured epoxy resin. The regenerated anhydride-cured epoxy resin exhibits excellent mechanical properties, with overall performance not significantly different from that of undegraded anhydride-cured epoxy resin, resulting in high recycling value.

Description

Technical Field

[0001] This invention belongs to the field of epoxy resin and its degradation and regeneration, and particularly relates to a method for degradation, recycling and reuse of anhydride-cured epoxy resin. Background Technology

[0002] Epoxy resin refers to organic compounds containing two or more epoxy groups in their molecules. Compared with other thermosetting resins, cured epoxy resins exhibit superior mechanical properties, dimensional stability, chemical stability, adhesive properties, and insulation properties. Cured epoxy resins can be used as binders, coatings, repair materials, insulating materials, and matrix resins for composite materials, and are widely applied in shipbuilding, automotive, construction, aerospace, and electronics industries.

[0003] Although cured epoxy resins offer excellent performance, they are difficult to degrade in nature. Therefore, cured epoxy resin products are often difficult to recycle, leading to resource waste and environmental pollution. Traditional methods typically involve landfilling or incineration of waste epoxy resin products. However, these products often contain high-value materials, such as precious metals like gold, palladium, copper, and rare earth elements in discarded printed circuit boards, and carbon fibers or glass fibers in discarded high-performance composite materials. Therefore, traditional methods also contribute to resource waste and environmental pollution. Furthermore, the mechanical properties of recycled epoxy resins are difficult to restore to the levels of undegraded anhydride-cured epoxy resins.

[0004] Currently, the main methods for degradation and recycling of cured epoxy resin products include: physical degradation and recycling, thermal degradation and recycling, biodegradation and recycling, photodegradation and recycling, and chemical degradation and recycling. Physical degradation recycling involves mechanically crushing waste materials and using them directly as fillers. This method has low production costs and is simple to process, but it damages the structure of epoxy resin during the recycling process, reducing its usability. Thermal degradation recycling involves directly burning waste materials to obtain heat energy. This method usually releases a large amount of toxic gases, polluting the environment and harming human health. Direct combustion also wastes high-value-added materials. Biodegradation recycling uses enzymes and other biomass catalysts to degrade the resin matrix into small-molecule monomers or oligomers. This method is mild and environmentally friendly, but has low degradation efficiency. Photodegradation recycling decomposes the resin matrix under the action of light. This method has high degradation efficiency and mild and environmentally friendly conditions, but usually requires the addition of initiators to the degradation system and has high energy consumption. Chemical degradation recycling uses chemical methods to degrade the resin matrix into small-molecule monomers or oligomers. Due to its mild recycling conditions and high recovery rate, it has become the most commonly used recycling method.

[0005] Currently, the chemical degradation and recycling method used for anhydride-cured epoxy resins is usually carried out under acidic or alkaline conditions. However, strong alkaline degradation of cured epoxy resins usually requires high temperature or high pressure conditions, which consumes a lot of energy and the recyclables are of low availability. Degrading cured epoxy resins under acidic conditions can achieve low-temperature degradation and consume less energy, but acidic solvents can corrode equipment.

[0006] Therefore, achieving rapid and efficient degradation, recycling, and reuse of anhydride-cured epoxy resins under mild conditions, and obtaining epoxy resins with high recycling value, is an urgent problem to be solved. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for catalytic degradation of anhydride-cured epoxy resin. This method enables rapid and efficient degradation of epoxy resin under mild conditions, and the resulting degradation products contain active groups that can be further recycled. This invention also provides a method for regenerating anhydride-cured epoxy resin. The regenerated anhydride-cured epoxy resin exhibits excellent mechanical properties, with overall performance not significantly different from that of undegraded anhydride-cured epoxy resin, resulting in high recycling value.

[0008] The purpose of this invention is to provide a zinc catalyst, the structure of which is shown in formula (I) or formula (II):

[0009] Equation (I), Equation (II);

[0010] Wherein, X is selected from H, methyl, isopropyl, tert-butyl, phenyl, diphenylmethyl, triphenylmethyl or naphthyl; R1 and R2 are independently selected from ethyl, propyl, diisopropylamine, butyl, pentyl, hexyl, phenyl, benzyl or methoxy(methyl)amine; R3 and R4 are independently selected from methyl or methoxy.

[0011] Another object of the present invention is to provide a method for preparing a zinc catalyst, comprising the following steps:

[0012] S1. Hydroxybenzaldehyde Formaldehyde and an acid catalyst are mixed and reacted to yield substituted hydroxybenzaldehyde. ;

[0013] S2. Replacement of hydroxybenzaldehyde The reaction with the secondary amine R1R2NH yields a substituted hydroxyketone compound. ;

[0014] S3. The substituted hydroxyketone compound With alkylamine compounds The reaction yields an imine compound. ;

[0015] S4. Imine compounds With substituted benzyl alcohols The reaction yields the aminoimine ligand. ;

[0016] S5. The aminoimine ligand The zinc catalyst is obtained by reacting with zinc acetate.

[0017] Wherein, X is selected from H, methyl, isopropyl, tert-butyl, phenyl, diphenylmethyl, triphenylmethyl or naphthyl; R1 and R2 are independently selected from ethyl, propyl, diisopropylamine, butyl, pentyl, hexyl, phenyl, benzyl or methoxy(methyl)amine; R3 and R4 are independently selected from methyl or methoxy; R5 and R6 are selected from H or R5 and R6 form an alkyl six-membered ring.

[0018] In some embodiments of the present invention, in S1, the hydroxybenzaldehyde The molar ratio with formaldehyde is 1:1.

[0019] In some embodiments of the present invention, in S1, the acid catalyst is selected from at least one of concentrated sulfuric acid, zinc chloride, and methanesulfonic acid.

[0020] In some embodiments of the present invention, in S1, the solvent for the reaction is selected from at least one of dichloromethane and ethyl acetate.

[0021] In some embodiments of the present invention, in S1, the reaction temperature is 30~90°C and the time is 2~8 hours.

[0022] In some embodiments of the present invention, in S2, the substituted hydroxybenzaldehyde The molar ratio of the secondary amine R1R2NH to the secondary amine is 0.4~0.7:1.

[0023] In some embodiments of the present invention, in S2, the catalyst used in the reaction is aluminum trichloride.

[0024] In some embodiments of the present invention, in S2, the molar ratio of the secondary amine R1R2NH to aluminum trichloride is 1:1.

[0025] In some embodiments of the present invention, in S2, the solvent for the reaction is m-trimethylbenzene.

[0026] In some embodiments of the present invention, in S2, the reaction temperature is 145~185°C and the time is 3~6 hours.

[0027] In some embodiments of the present invention, in S3, the substituted hydroxyketone compound With alkylamine compounds The molar ratio is 1:1.05~1.15.

[0028] In some embodiments of the present invention, in S3, the solvent for the reaction is n-hexane or petroleum ether.

[0029] In some embodiments of the present invention, in step S3, the reaction temperature is room temperature and the time is 3 to 6 hours.

[0030] In some embodiments of the present invention, in S4, the imine compound With substituted benzyl alcohols The molar ratio is 1:0.3~0.6.

[0031] In some embodiments of the present invention, in S4, the catalyst used in the reaction is aluminum trichloride.

[0032] In some embodiments of the present invention, in S4, the molar ratio of the imine compound to aluminum trichloride is 1:1.

[0033] In some embodiments of the present invention, in step S4, the solvent for the reaction is m-trimethylbenzene.

[0034] In some embodiments of the present invention, in step S4, the reaction temperature is 150~190°C and the time is 4~8 hours.

[0035] In some embodiments of the present invention, in S5, the aminoimine ligand The molar ratio with zinc acetate is 1:1.

[0036] In some embodiments of the present invention, in step S5, the solvent for the reaction is toluene.

[0037] In some embodiments of the present invention, in step S5, the temperature of the reaction is -78 to 25°C, and the time is 24 to 48 hours.

[0038] Another object of the present invention is to provide a method for catalytic degradation of anhydride-cured epoxy resin, comprising the following steps:

[0039] A biodegradable anhydride-cured epoxy resin, a zinc catalyst, and a solvent are mixed and subjected to a degradation reaction to obtain the degradation product of the anhydride-cured epoxy resin.

[0040] In some embodiments of the present invention, the mass ratio of the degradable anhydride-cured epoxy resin to the zinc catalyst is 1:0.005~0.05.

[0041] In some embodiments of the present invention, the degradation reaction is carried out at a temperature of 50-80°C for 5-10 hours.

[0042] In some embodiments of the present invention, the solvent is selected from at least one of dichloromethane, acetone, methyl ethyl ketone, cyclohexanone, ethyl acetate, ethylene glycol methyl ether, propylene glycol methyl ether, chloroform, and carbon tetrachloride.

[0043] Another object of the present invention is to provide a method for regenerating anhydride-cured epoxy resin, comprising the following steps: mixing the degradation products of the anhydride-cured epoxy resin, an anhydride curing agent and a curing accelerator, and heating and curing to obtain regenerated anhydride-cured epoxy resin.

[0044] In some embodiments of the present invention, the anhydride curing agent is selected from at least one of phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, dodecenylsuccinic anhydride, methylhexahydrophthalic anhydride, and pyromellitic dianhydride.

[0045] In some embodiments of the present invention, the curing accelerator is selected from at least one of 2,4,6-tris(dimethylaminomethyl)benzene, benzyldimethylamine, 1,8-diazabicyclo(5,4,0)-7-undecene, 2-ethyl-4-methylimidazolium, 1,5,7-trizabicyclo[4.4.0]dec-5-ene, 2-mercaptobenzothiazole, 1-cyanoethyl-2-ethyl-4-methylimidazolium, and metal salts of acetylacetone.

[0046] In some embodiments of the present invention, the mass ratio of the degradation product of the anhydride-cured epoxy resin, the anhydride curing agent, and the curing accelerator is 1:0.6~0.9:0.01~0.03.

[0047] In some embodiments of the present invention, the temperature for heating and curing is 80~120℃ and the time is 20~40min.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] (1) The regenerated anhydride-cured epoxy resin of the present invention has good mechanical properties and its comprehensive properties are not much different from those of undegraded anhydride-cured epoxy resin, and its recycling value is high.

[0050] (2) The method of catalytic anhydride curing epoxy resin degradation of the present invention can achieve rapid and efficient degradation of epoxy resin under mild conditions. The generated degradation products contain active groups and can be further recycled.

[0051] (3) This invention designs and synthesizes various types of salalen ligands. The salalen ligands are combined with zinc metal to obtain a zinc catalyst. The zinc catalyst has good stability, has both Lewis acid zinc ions and Lewis basic tertiary amine groups introduced on the side arms. The Lewis acid zinc ions can catalyze the activation of ester groups, while the tertiary amine groups can activate nucleophiles. The zinc catalyst is used to degrade epoxy resin, which can achieve rapid and efficient degradation of epoxy resin under mild conditions.

[0052] (4) The present invention introduces a nitrogen-containing basic group into the structure of the zinc catalyst, so that the zinc catalyst can both activate the nucleophile and not weaken the Lewis acidity of the metal center due to the coordination with the zinc metal. This ensures that the zinc center has a certain degree of openness and enough space to activate the ester group, but the space of the zinc center is not too open, thus ensuring its high stability. Detailed Implementation

[0053] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0054] Biodegradable anhydride-cured epoxy resins are commercially available.

[0055] The degradation diagram of the biodegradable anhydride-cured epoxy resin of the present invention is shown below:

[0056] .

[0057] The preparation process of the zinc catalyst of the present invention is shown in the following schematic diagram:

[0058] .

[0059] Example 1

[0060] This embodiment provides a zinc catalyst C1, the preparation process of which includes the following steps:

[0061] S1. Mix o-hydroxybenzaldehyde (5 mol), formaldehyde (5 mol), concentrated sulfuric acid (0.8 mol), and dichloromethane (100 ml), and react at 30 °C for 8 hours. After the reaction is complete, pass a solution of ethyl acetate:petroleum ether (volume ratio 1:10) through a silica gel column, collect the product, remove the solvent by rotary evaporation, and dry to obtain substituted hydroxybenzaldehyde. ;

[0062] S2. Replacement of hydroxybenzaldehyde A mixture of 5 mol of diethylamine, 10 mol of aluminum trichloride, and 150 ml of m-trimethylbenzene was prepared and reacted at 165 °C for 5 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:9 of ethyl acetate:petroleum ether. The solvent was removed by rotary evaporation, and the product was dried to obtain the substituted hydroxyketone compound. ;

[0063] S3. The substituted hydroxyketone compound (5 mol), alkylamine compounds (5.5 mol) and n-hexane (150 ml) were mixed and stirred at room temperature for 5 hours. After the reaction was completed, anhydrous MgSO4 was added to remove water, and the mixture was filtered. The product was then passed through a silica gel column in a volume ratio of 1:15 of ethyl acetate:n-hexane. The product was collected, the solvent was removed by rotary evaporation, and the product was dried to obtain an imine compound. ;

[0064] S4. Imine compounds (10 mol) substituted benzyl alcohol 5 mol of ethyl acetate, 10 mol of aluminum trichloride, and 150 ml of m-trimethylbenzene were mixed and reacted at 165 °C for 5 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:10 of ethyl acetate:petroleum ether. The product was collected, the solvent was removed by rotary evaporation, and the product was dried to obtain the aminoimine ligand. ;

[0065] S5. Under a nitrogen atmosphere, aminoimine ligands (5 mol) was dissolved in 150 ml of toluene. At -78 °C, zinc acetate (5 mol) dissolved in toluene was added. The mixture was heated to room temperature and reacted for 30 hours. After the reaction was completed, the solvent was removed by rotary evaporation. The mixture was recrystallized from n-hexane, filtered to remove the solvent, and dried to obtain zinc catalyst C1. ;

[0066] The zinc catalyst C1 was characterized by nuclear magnetic resonance (NMR), and its 1H NMR spectrum is as follows:

[0067] 1H-NMR(CDCl3,400M-Hz), δ(ppm): 8.12(s,1H,CH), 7.63(d,1H,Ph), 7.23(d,1H,Ph), 7.10(d,1H,Ph), 6.49(s,1H,Ph), 6.38(s,1H,Ph), 3.84(s,3H,OCH3), 3.80(s,3H,OCH3), 3.72(s,2H,CH2), 3.64(t,2H,CH2), 3.61(s,2H,CH2), 2.73(t,2H,CH2), 2.54(m,4H,CH2), 2.27(s,3H,CH3), 1.03(t,6H,CH3).

[0068] Example 2

[0069] This embodiment provides a zinc catalyst C2, the preparation process of which includes the following steps:

[0070] S1. Hydroxybenzaldehyde A mixture of 5 mol of formaldehyde, 0.8 mol of concentrated sulfuric acid, and 100 ml of dichloromethane was prepared and reacted at 30 °C for 8 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:10 of ethyl acetate:petroleum ether. The solvent was removed by rotary evaporation, and the product was dried to obtain substituted hydroxybenzaldehyde. ;

[0071] S2. Replacement of hydroxybenzaldehyde 5 mol of diisopropylamine, 10 mol of aluminum trichloride, and 150 ml of m-trimethylbenzene were mixed and reacted at 165 °C for 5 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:9 of ethyl acetate:petroleum ether. The solvent was removed by rotary evaporation and the product was dried to obtain the substituted hydroxyketone compound. ;

[0072] S3. The substituted hydroxyketone compound (5 mol), alkylamine compounds (5.5 mol) and n-hexane (150 ml) were mixed and stirred at room temperature for 5 hours. After the reaction was completed, anhydrous MgSO4 was added to remove water, and the mixture was filtered. The product was then passed through a silica gel column in a volume ratio of 1:15 of ethyl acetate:n-hexane. The product was collected, the solvent was removed by rotary evaporation, and the product was dried to obtain an imine compound. ;

[0073] S4. Imine compounds (10 mol) substituted benzyl alcohol 5 mol of ethyl acetate, 10 mol of aluminum trichloride, and 150 ml of m-trimethylbenzene were mixed and reacted at 165 °C for 5 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:10 of ethyl acetate:petroleum ether. The product was collected, the solvent was removed by rotary evaporation, and the product was dried to obtain the aminoimine ligand. ;

[0074] S5. Under a nitrogen atmosphere, aminoimine ligands (5 mol) was dissolved in 150 ml of toluene. At -78 °C, zinc acetate (5 mol) dissolved in toluene was added. The mixture was heated to room temperature and reacted for 30 hours. After the reaction was completed, the solvent was removed by rotary evaporation. The mixture was recrystallized from n-hexane, filtered to remove the solvent, and dried to obtain the zinc catalyst C2. ;

[0075] The zinc catalyst C2 was characterized by nuclear magnetic resonance (NMR), and its 1H NMR spectrum is as follows:

[0076] 1 H-NMR(CDCl3,400M-Hz), δ(ppm): 8.19(s,1H,CH), 7.54(s,1H,Ph), 7.06(s,1H,Ph), 6.89(s,1H,Ph), 6.81(s,1H,Ph), 6.66(s,2H,CH2), 6.60(s,2H,CH2), 3.03(m,1H,CH), 2.69(m,2H,CH), 2.61(m,1H,CH), 2.35(s,3H,CH3), 2.27(s,3H,CH3), 2.19-2.15(m,8H,CH2and CH3), 1.66-1.56(m,4H,CH2), 1.23(m,2H,CH2), 1.00(d,12H,CH3).

[0077] Example 3

[0078] This embodiment provides a zinc catalyst C3, the preparation process of which includes the following steps:

[0079] S1. Hydroxybenzaldehyde A mixture of 5 mol of formaldehyde, 0.8 mol of concentrated sulfuric acid, and 100 ml of dichloromethane was prepared and reacted at 30 °C for 8 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:10 of ethyl acetate:petroleum ether. The solvent was removed by rotary evaporation, and the product was dried to obtain substituted hydroxybenzaldehyde. ;

[0080] S2. Replacement of hydroxybenzaldehyde A mixture of 5 mol of diphenylamine, 10 mol of aluminum trichloride, and 150 ml of m-trimethylbenzene was prepared and reacted at 165 °C for 5 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:9 of ethyl acetate:petroleum ether. The solvent was removed by rotary evaporation, and the product was dried to obtain the substituted hydroxyketone compound. ;

[0081] S3. The substituted hydroxyketone compound (5 mol), alkylamine compounds (5.5 mol) and n-hexane (150 ml) were mixed and stirred at room temperature for 5 hours. After the reaction was completed, anhydrous MgSO4 was added to remove water, and the mixture was filtered. The product was then passed through a silica gel column in a volume ratio of 1:15 of ethyl acetate:n-hexane. The product was collected, the solvent was removed by rotary evaporation, and the product was dried to obtain an imine compound. ;

[0082] S4. Imine compounds (10 mol) substituted benzyl alcohol 5 mol of ethyl acetate, 10 mol of aluminum trichloride, and 150 ml of m-trimethylbenzene were mixed and reacted at 165 °C for 5 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:10 of ethyl acetate:petroleum ether. The product was collected, the solvent was removed by rotary evaporation, and the product was dried to obtain the aminoimine ligand. ;

[0083] S5. Under a nitrogen atmosphere, aminoimine ligands (5 mol) was dissolved in 150 ml of toluene. At -78 °C, zinc acetate (5 mol) dissolved in toluene was added. The mixture was heated to room temperature and reacted for 30 hours. After the reaction was completed, the solvent was removed by rotary evaporation. The mixture was recrystallized from n-hexane, filtered to remove the solvent, and dried to obtain zinc catalyst C3. ;

[0084] The zinc catalyst C3 was characterized by nuclear magnetic resonance (NMR), and its 1H NMR spectrum is as follows:

[0085] 1H-NMR(CDCl3,400M-Hz), δ(ppm): 8.21(s,1H,CH), 7.69(s,1H,Ph), 7.40-7.33(m,8H,Ph), 7.20(s,1H,Ph), 7.06(t,2H,Ph), 6.48(s,1H,Ph), 6.36(s,1H,Ph), 4.33(s,2H,CH2), 3.83(s,3H,OCH3), 3.81(s,3H,OCH3), 3.61(s,2H,CH2), 3.04(m,1H,CH),2.62(m,1H,CH), 2.27(s,3H,CH3), 1.19(m,2H,CH2), 1.67-1.55(m,4H,CH2), 1.34(s,9H,CH3), 1.20(m,2H,CH2).

[0086] Example 4

[0087] This embodiment provides a zinc catalyst C4, the preparation process of which includes the following steps:

[0088] S1. Hydroxybenzaldehyde A mixture of 5 mol of formaldehyde, 0.8 mol of concentrated sulfuric acid, and 100 ml of dichloromethane was prepared and reacted at 30 °C for 8 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:10 of ethyl acetate:petroleum ether. The solvent was removed by rotary evaporation, and the product was dried to obtain substituted hydroxybenzaldehyde. ;

[0089] S2. Replacement of hydroxybenzaldehyde A mixture of 5 mol of dibenzylamine, 10 mol of aluminum trichloride, and 150 ml of m-trimethylbenzene was prepared and reacted at 165 °C for 5 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:9 of ethyl acetate:petroleum ether. The solvent was removed by rotary evaporation, and the product was dried to obtain the substituted hydroxyketone compound. ;

[0090] S3. The substituted hydroxyketone compound (5 mol), alkylamine compounds (5.5 mol) and n-hexane (150 ml) were mixed and stirred at room temperature for 5 hours. After the reaction was completed, anhydrous MgSO4 was added to remove water, and the mixture was filtered. The product was then passed through a silica gel column in a volume ratio of 1:15 of ethyl acetate:n-hexane. The product was collected, the solvent was removed by rotary evaporation, and the product was dried to obtain an imine compound. ;

[0091] S4. Imine compounds (10 mol) substituted benzyl alcohol 5 mol of ethyl acetate, 10 mol of aluminum trichloride, and 150 ml of m-trimethylbenzene were mixed and reacted at 165 °C for 5 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:10 of ethyl acetate:petroleum ether. The product was collected, the solvent was removed by rotary evaporation, and the product was dried to obtain the aminoimine ligand. ;

[0092] S5. Under a nitrogen atmosphere, aminoimine ligands (5 mol) was dissolved in 150 ml of toluene. At -78 °C, zinc acetate (5 mol) dissolved in toluene was added. The temperature was raised to room temperature and the reaction was allowed to proceed for 30 hours. After the reaction was completed, the solvent was removed by rotary evaporation. The product was recrystallized from n-hexane, filtered to remove the solvent, and dried to obtain zinc catalyst C4. ;

[0093] The zinc catalyst C4 was characterized by nuclear magnetic resonance (NMR), and its 1H NMR spectrum is as follows:

[0094] 1 H-NMR(CDCl3,400M-Hz), δ(ppm): 8.10(s,1H,CH), 7.94(s,1H,Ph), 7.75(d,2H,Ph), 7.64(s,1H,Ph), 7.49-7.41(m,3H,Ph), 7.29-7.21(m,10H,Ph), 6.85(s,1H,Ph),6.817(s,1H,Ph), 3.66-3.62(m,10H,CH2), 2.73(t,2H,CH2), 2.28(s,3H,CH3), 1.18(s,3H,CH3), 1.15(s,3H,CH3).

[0095] Example 5

[0096] This embodiment provides a zinc catalyst C5, the preparation process of which includes the following steps:

[0097] S1. Hydroxybenzaldehyde A mixture of 5 mol of formaldehyde, 0.8 mol of concentrated sulfuric acid, and 100 ml of dichloromethane was prepared and reacted at 30 °C for 8 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:10 of ethyl acetate:petroleum ether. The solvent was removed by rotary evaporation, and the product was dried to obtain substituted hydroxybenzaldehyde. ;

[0098] S2. Replacement of hydroxybenzaldehyde A mixture of 5 mol of methoxy(methyl)amine, 10 mol of aluminum trichloride, and 150 ml of m-trimethylbenzene was reacted at 165 °C for 5 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:9 of ethyl acetate:petroleum ether. The solvent was removed by rotary evaporation, and the product was dried to obtain the substituted hydroxyketone compound. ;

[0099] S3. The substituted hydroxyketone compound (5 mol), alkylamine compounds (5.5 mol) and n-hexane (150 ml) were mixed and stirred at room temperature for 5 hours. After the reaction was completed, anhydrous MgSO4 was added to remove water, and the mixture was filtered. The product was then passed through a silica gel column in a volume ratio of 1:15 of ethyl acetate:n-hexane. The product was collected, the solvent was removed by rotary evaporation, and the product was dried to obtain an imine compound. ;

[0100] S4. Imine compounds (10 mol) substituted benzyl alcohol 5 mol of ethyl acetate, 10 mol of aluminum trichloride, and 150 ml of m-trimethylbenzene were mixed and reacted at 165 °C for 5 hours. After the reaction was completed, the product was passed through a silica gel column in a volume ratio of 1:10 of ethyl acetate:petroleum ether. The product was collected, the solvent was removed by rotary evaporation, and the product was dried to obtain the aminoimine ligand. ;

[0101] S5. Under a nitrogen atmosphere, aminoimine ligands (5 mol) was dissolved in 150 ml of toluene. At -78 °C, zinc acetate (5 mol) dissolved in toluene was added. The mixture was heated to room temperature and reacted for 30 hours. After the reaction was completed, the solvent was removed by rotary evaporation. The mixture was recrystallized from n-hexane, filtered to remove the solvent, and dried to obtain zinc catalyst C5. ;

[0102] The zinc catalyst C5 was characterized by nuclear magnetic resonance (NMR), and its 1H NMR spectrum is as follows:

[0103] 1H-NMR(CDCl3,400M-Hz), δ(ppm): 8.22(s,1H,CH), 7.70(s,1H,Ph), 7.20(s,1H,Ph), 6.49(s,1H,Ph), 6.35(s,1H,Ph), 3.84(s,3H,CH3), 3.80(s,5H,CH2and CH3),3.62(s,2H,CH2), 3.57(s,3H,CH3), 3.03(m,1H,CH), 2.61(m,1H,CH), 2.47(s,3H,CH3),2.28(s,3H,CH3), 2.16(m,2H,CH2), 1.66-1.55(m,4H,CH2), 1.36(s,9H,CH3), 1.19(m,2H,CH2).

[0104] Example 6

[0105] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0106] 100 g of degradable anhydride-cured epoxy resin, 0.5 g of zinc catalyst C1, and 100 g of dichloromethane were mixed and reacted at 80 °C for 5 hours. After cooling to room temperature, the undegraded anhydride-cured epoxy resin was removed by filtration. The filtrate was concentrated under reduced pressure to remove dichloromethane. The concentrate was added dropwise to n-hexane to precipitate the resin. The precipitate was dried to obtain the anhydride-cured epoxy resin degradation product A1. After the reaction was completed, the undegraded anhydride-cured epoxy resin was taken out, washed successively with ethyl acetate and acetone, dried, and weighed. The degradation rate of the degradable anhydride-cured epoxy resin was calculated.

[0107] Example 7

[0108] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0109] 100g of degradable anhydride-cured epoxy resin, 5g of zinc catalyst C1, and 200g of dichloromethane were mixed and reacted at 50°C for 10 hours. After cooling to room temperature, the undegraded anhydride-cured epoxy resin was removed by filtration. The filtrate was concentrated under reduced pressure to remove dichloromethane. The concentrate was added dropwise to n-hexane to precipitate the resin. The precipitate was dried to obtain the anhydride-cured epoxy resin degradation product A2. After the reaction was completed, the undegraded anhydride-cured epoxy resin was taken out, washed successively with ethyl acetate and acetone, dried, and weighed. The degradation rate of the degradable anhydride-cured epoxy resin was calculated.

[0110] Example 8

[0111] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0112] 100 g of degradable anhydride-cured epoxy resin, 0.5 g of zinc catalyst C2, and 100 g of dichloromethane were mixed and reacted at 80 °C for 5 hours. After cooling to room temperature, the undegraded anhydride-cured epoxy resin was removed by filtration. The filtrate was concentrated under reduced pressure to remove dichloromethane. The concentrate was added dropwise to n-hexane to precipitate the resin. The precipitate was dried to obtain the anhydride-cured epoxy resin degradation product A3. After the reaction was completed, the undegraded anhydride-cured epoxy resin was taken out, washed successively with ethyl acetate and acetone, dried, and weighed. The degradation rate of the degradable anhydride-cured epoxy resin was calculated.

[0113] Example 9

[0114] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0115] 100 g of degradable anhydride-cured epoxy resin, 0.5 g of zinc catalyst C3, and 100 g of dichloromethane were mixed and reacted at 80 °C for 5 hours. After cooling to room temperature, the undegraded anhydride-cured epoxy resin was removed by filtration. The filtrate was concentrated under reduced pressure to remove dichloromethane. The concentrate was added dropwise to n-hexane to precipitate the resin. The precipitate was dried to obtain the anhydride-cured epoxy resin degradation product A4. After the reaction was completed, the undegraded anhydride-cured epoxy resin was taken out, washed successively with ethyl acetate and acetone, dried, and weighed. The degradation rate of the degradable anhydride-cured epoxy resin was calculated.

[0116] Example 10

[0117] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0118] 100 g of biodegradable anhydride-cured epoxy resin, 0.5 g of zinc catalyst C4, and 100 g of dichloromethane were mixed and reacted at 80 °C for 5 hours. After cooling to room temperature, the undegraded anhydride-cured epoxy resin was removed by filtration. The filtrate was concentrated under reduced pressure to remove dichloromethane. The concentrate was added dropwise to n-hexane to precipitate the resin. The precipitate was dried to obtain the degradation product A5 of the anhydride-cured epoxy resin. After the reaction was completed, the undegraded anhydride-cured epoxy resin was taken out, washed successively with ethyl acetate and acetone, dried, and weighed. The degradation rate of the biodegradable anhydride-cured epoxy resin was calculated.

[0119] Example 11

[0120] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0121] 100 g of degradable anhydride-cured epoxy resin, 0.5 g of zinc catalyst C5, and 100 g of dichloromethane were mixed and reacted at 80 °C for 5 hours. After cooling to room temperature, the undegraded anhydride-cured epoxy resin was removed by filtration. The filtrate was concentrated under reduced pressure to remove dichloromethane. The concentrate was added dropwise to n-hexane to precipitate the resin. The precipitate was dried to obtain the anhydride-cured epoxy resin degradation product A6. After the reaction was completed, the undegraded anhydride-cured epoxy resin was taken out, washed successively with ethyl acetate and acetone, dried, and weighed. The degradation rate of the degradable anhydride-cured epoxy resin was calculated.

[0122] Example 12

[0123] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0124] The degradation product A1 (100g), hexahydrophthalic anhydride (60g), and 2,4,6-tris(dimethylaminomethyl)benzene (3g) were added to a reactor, heated to 100℃, and cured for 30 min to obtain regenerated anhydride-cured epoxy resin B1.

[0125] Example 13

[0126] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0127] The degradation product A2 (100g) of the anhydride-cured epoxy resin, phthalic anhydride (90g) and benzyl dimethylamine (1g) were added to the reactor, heated to 80℃ and cured for 40min to obtain regenerated anhydride-cured epoxy resin B2.

[0128] Example 14

[0129] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0130] The degradation product A3 (100g), tetrahydrophthalic anhydride (70g), and benzyl dimethylamine (2g) of anhydride-cured epoxy resin were added to a reactor, heated to 110°C, and cured for 20 minutes to obtain regenerated anhydride-cured epoxy resin B3.

[0131] Example 15

[0132] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0133] The degradation product A4 (100g) of the anhydride-cured epoxy resin, methyltetrahydrophthalic anhydride (80g) and 1,8-diazabicyclo(5,4,0)-7-undecene (1.5g) were added to a reactor, heated to 90℃ and cured for 25 min to obtain regenerated anhydride-cured epoxy resin B4.

[0134] Example 16

[0135] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0136] The degradation product A5 (100g) of anhydride-cured epoxy resin, methyl hexahydrophthalic anhydride (85g) and 2-ethyl-4-methylimidazole (2.5g) were added to a reactor, heated to 100℃ and cured for 35 minutes to obtain regenerated anhydride-cured epoxy resin B5.

[0137] Example 17

[0138] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0139] The degradation product A6 (100g) of the anhydride-cured epoxy resin, pyromellitic dianhydride (65g) and 2-mercaptobenzothiazole (2g) were added to a reactor, heated to 105℃ and cured for 30min to obtain regenerated anhydride-cured epoxy resin B6.

[0140] Comparative Example 1

[0141] This comparative example provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0142] 10 g of biodegradable anhydride-cured epoxy resin and 83.3 g of sodium hydroxide aqueous solution (10 wt%) were added to a reactor. The mixture was heated to 80 °C and reacted for 8 hours. After cooling to room temperature, the undegraded anhydride-cured epoxy resin was removed by filtration. The filtrate was neutralized with acetic acid, concentrated under reduced pressure, and the water was removed. The concentrate was added dropwise to n-hexane to precipitate the resin. The precipitate was dried to obtain the degradation product A7 of the anhydride-cured epoxy resin. After the reaction was completed, the undegraded anhydride-cured epoxy resin was removed, washed successively with ethyl acetate and acetone, dried, and weighed. The degradation rate of the biodegradable anhydride-cured epoxy resin was calculated.

[0143] Comparative Example 2

[0144] This comparative example provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0145] The degradation product A7 (100g) of the anhydride-cured epoxy resin, pyromellitic dianhydride (65g) and 2-mercaptobenzothiazole (2g) were added to the reactor, heated to 105℃ and cured for 30min to obtain regenerated anhydride-cured epoxy resin B7.

[0146] Comparative Example 3

[0147] The raw materials used are those in Examples 6-11 or Comparative Example 1: biodegradable anhydride-cured epoxy resin.

[0148] Performance testing:

[0149] The degradation of the degradable anhydride-cured epoxy resins of Examples 6-11 and Comparative Example 1 is shown in Table 1.

[0150] Table 1. Degradation rates of the degradable anhydride-cured epoxy resins of Examples 6-11 and Comparative Example 1.

[0151]

[0152] As shown in Table 1, the biodegradable anhydride-cured epoxy resins of Examples 6-11 of the present invention have high degradation rates.

[0153] The performance of the regenerated anhydride-cured epoxy resins of Examples 12-17 and Comparative Example 2, and the biodegradable anhydride-cured epoxy resin of Comparative Example 3 were tested, and the results are shown in Table 2.

[0154] Glass transition temperature: obtained using a TA-Q200 differential scanning calorimeter manufactured by TA Instruments, USA.

[0155] Bending strength and bending modulus: tested according to ISO 178 standard, with a sample size of 80mm x 10mm x 4mm and a test rate of 2mm / min.

[0156] Impact strength: The test was conducted using a Sansi ZBC-50 single-arm pendulum impact tester in accordance with GB / T 1843-2008.

[0157] Tensile strength, tensile modulus, and elongation at break: The regenerated anhydride-cured epoxy resins of Examples 12-17 and Comparative Example 2, or the biodegradable anhydride-cured epoxy resin of Comparative Example 3, were cast into dumbbell-shaped molds. After curing, demolding, and surface polishing, standard samples with a thickness of 4 mm were obtained. The tensile properties were tested at a tensile rate of 5 mm / min according to ISO 527 standard.

[0158] Table 2. Properties of regenerated anhydride-cured epoxy resin.

[0159]

[0160] As shown in Table 2, although the glass transition temperature, tensile strength, tensile modulus and flexural modulus of the biodegradable anhydride-cured epoxy resins of Examples 5-1 decreased after regeneration, the flexural strength, elongation at break and impact strength increased. The overall performance was not much different from that of the untreated biodegradable anhydride-cured epoxy resin, indicating that the biodegradable anhydride-cured epoxy resin of the present invention has high recycling value after degradation.

[0161] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that after reading this application specification, they can still modify or make equivalent substitutions to the specific implementation of the present invention, but these modifications or changes do not depart from the protection scope of the pending claims of the present invention.

Claims

1. A zinc catalyst, characterized in that, The structure of the zinc catalyst is shown in formula (I) or formula (II): formula (I) formula (II) Wherein, X is selected from H, methyl, isopropyl, tert-butyl, phenyl, benzhydryl, trityl or naphthyl; R1, R2 are independently selected from ethyl, propyl, diisopropylamine, butyl, pentyl, hexyl, phenyl, benzyl or methoxy(methyl)amine; R3, R4 are independently selected from methyl or methoxy.

2. A process for the preparation of a zinc catalyst, characterized in that, The method comprises the following steps: S1. mixing hydroxybenzaldehyde , formaldehyde and an acid catalyst, reacting, to give substituted hydroxybenzaldehyde ; S2. The substituted hydroxybenzaldehyde is reacted with a secondary amine R1R2NH to give a substituted hydroxyketone compound ; S3. reacting the substituted hydroxy ketone compound with an alkyl amine compound to form an imine compound ; S4. The imine compound with a substituted benzyl alcohol to give the amino imine ligand ; S5. reacting the amino imine ligand with zinc acetate to obtain the zinc catalyst of claim 1. Wherein, X is selected from H, methyl, isopropyl, tert-butyl, phenyl, benzhydryl, trityl or naphthyl; R1, R2 are independently selected from ethyl, propyl, diisopropylamine, butyl, pentyl, hexyl, phenyl, benzyl or methoxy(methyl)amine; R3, R4 are independently selected from methyl or methoxy; R5, R6 are selected from H or R5, R6 form an alkyl six-membered ring.

3. The method of preparing a zinc catalyst according to claim 2, characterized in that, said hydroxybenzaldehyde a molar ratio of 1 : 1 with formaldehyde; and / or the substituted hydroxybenzaldehyde with a secondary amine R1R2NH in a molar ratio of 0.4 to 0.7 : 1 ; and / or, the substituted hydroxyketone compound with an alkyl amine compound at a molar ratio of 1 : 1.05~1.15; and / or the imine compound with a substituted benzyl alcohol in a molar ratio of 1 :0.3-0.6; and / or, an amino imine ligand The molar ratio to zinc acetate was 1:

1.

4. The method of preparing a zinc catalyst according to claim 2, characterized in that, In S1, the acid catalyst is selected from at least one of concentrated sulfuric acid, zinc chloride and methyl sulfonic acid.

5. A method of catalyzing the degradation of an epoxy resin cured with an acid anhydride, characterized in that, The method comprises the following steps: The degradable anhydride-cured epoxy resin, the zinc catalyst and the solvent are mixed, and a degradation reaction is performed to obtain an anhydride-cured epoxy resin degradation product.

6. The method of claim 5, wherein the catalytic anhydride-cured epoxy resin is degraded by, The mass ratio of the degradable anhydride-cured epoxy resin to the zinc catalyst is 1:0.005-0.

05.

7. The method of claim 5, wherein the catalytic anhydride-cured epoxy resin is degraded by, The solvent is selected from at least one of dichloromethane, acetone, methyl ethyl ketone, cyclohexanone, ethyl acetate, ethylene glycol methyl ether, propylene glycol methyl ether, chloroform and carbon tetrachloride.

8. A method for regenerating an anhydride-cured epoxy resin, characterized by, The method comprises the following steps: The anhydride-cured epoxy resin degradation product, the anhydride curing agent and the curing accelerator are mixed, and heated and cured to obtain a regenerated anhydride-cured epoxy resin.

9. The method of regenerating an anhydride-cured epoxy resin according to claim 8, wherein, The anhydride curing agent is selected from at least one of phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, methyl hexahydrophthalic anhydride and pyromellitic dianhydride; The curing accelerator is selected from at least one of 2,4,6-tris(dimethylaminomethyl)benzene, benzyl dimethylamine, 1,8-diazabicyclo(5,4,0)-7-undecene, 2-ethyl-4-methylimidazole, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 2-mercaptobenzothiazole, 1-cyanoethyl-2-ethyl-4-methylimidazole and acetylacetone metal salt.

10. The method of regenerating an anhydride-cured epoxy resin according to claim 9, wherein The mass ratio of the anhydride-cured epoxy resin degradation product, the anhydride curing agent and the curing accelerator is 1:0.6-0.9:0.01-0.03.

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