Degradation recycling and reapplication method of anhydride cured epoxy resin

Abstract

The invention discloses a method for degrading, recycling and reapplying anhydride cured epoxy resin, and relates to the field of epoxy resin and degradation and regeneration thereof. The invention provides a method for catalyzing degradation of anhydride cured epoxy resin, the method can realize rapid and efficient degradation of epoxy resin under mild conditions, and the generated degradation product contains active groups and can be further recycled. The invention further provides a regeneration method of the anhydride cured epoxy resin, the regenerated anhydride cured epoxy resin is good in mechanical property after being degraded, the comprehensive performance of the anhydride cured epoxy resin is slightly different from that of non-degraded anhydride cured epoxy resin, and the recycling value of the anhydride cured epoxy resin is high.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of epoxy resin and its degradation and regeneration, and particularly relates to a degradation and recycling method of anhydride-cured epoxy resin. BACKGROUND

[0002] Epoxy resin refers to an organic compound containing two or more epoxy groups in the molecule. Compared with other thermosetting resins, the mechanical properties, dimensional stability, chemical stability, bonding properties, and insulation properties of cured epoxy resin are more excellent. Cured epoxy resin can be used as a cementing agent, a coating, a repair material, an insulating material, and a composite material matrix resin, and is widely used in the fields of ships, automobiles, buildings, aerospace, electronics, and electrical appliances.

[0003] Although the cured epoxy resin has excellent performance, it is difficult to degrade in nature, and therefore, cured epoxy resin products are usually difficult to recycle and process, which not only causes waste of resources, but also causes environmental pollution. The traditional treatment method usually uses landfill or incineration to treat waste epoxy resin products, but the waste epoxy resin products usually contain many materials with high added value, such as gold, palladium, copper, and rare earth metals in waste printed circuit boards, and carbon fibers or glass fibers in waste high-performance composite materials. Therefore, the traditional treatment method also causes waste of resources and pollution of the environment to some extent. In addition, the mechanical properties of the degraded and recycled epoxy resin are difficult to restore to the mechanical properties of the anhydride-cured epoxy resin that has not been degraded.

[0004] At present, the degradation and recycling methods of cured epoxy resin products mainly include physical degradation and recycling, thermal energy degradation and recycling, biological degradation and recycling, light degradation and recycling, and chemical degradation and recycling. Among them, physical degradation and recycling is to mechanically crush waste materials and directly use them as fillers. This method has low production cost and simple treatment method, but in the recycling process, the structure of the epoxy resin is damaged, resulting in a decrease in the utilization value of the epoxy resin. Thermal energy degradation and recycling refers to directly burning waste materials to obtain heat energy. This method usually releases a large amount of toxic gas, which not only pollutes the environment, but also harms human health. Direct combustion also causes waste of high-value-added materials. Biological degradation and recycling is a method of degrading resin matrix into small molecular monomers or oligomers under the action of biological catalysts such as enzymes. This method has mild conditions and is environmentally friendly, but the degradation efficiency is low. Light degradation and recycling is a method of degrading resin matrix under the action of light. This method has high degradation efficiency, mild degradation conditions, and environmental protection, but usually requires the addition of initiators in the degradation system and has high energy consumption. Chemical degradation and recycling is a method of degrading resin matrix into small molecular monomers or oligomers by chemical methods. Because of its mild recycling conditions and high recycling rate, it has become the most commonly used recycling method at present.

[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 of secondary amines with R1R2NH yields substituted hydroxyketone compounds. ;

[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: 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.

[0039] 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.

[0040] In some embodiments of the present invention, the degradation reaction is carried out at a temperature of 50-80°C for 5-10 hours.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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.

[0046] In some embodiments of the present invention, the temperature for heating and curing is 80~120℃ and the time is 20~40min.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (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.

[0049] (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.

[0050] (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.

[0051] (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

[0052] 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.

[0053] Biodegradable anhydride-cured epoxy resins are commercially available.

[0054] The degradation diagram of the biodegradable anhydride-cured epoxy resin of the present invention is shown below:

[0055]

[0056] The preparation process of the zinc catalyst of the present invention is shown below:

[0057]

[0058] Example 1

[0059] This embodiment provides a zinc catalyst C1, the preparation process of which includes the following steps:

[0060] 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. ;

[0061] 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. ;

[0062] 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. ;

[0063] 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. ;

[0064] 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. ;

[0065] The zinc catalyst C1 was characterized by nuclear magnetic resonance (NMR), and its 1H NMR spectrum is as follows:

[0066] 1 H-NMR (CDCl3, 400 M-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).

[0067] Example 2

[0068] This embodiment provides a zinc catalyst C2, the preparation process of which includes the following steps:

[0069] 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. ;

[0070] 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. ;

[0071] 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. ;

[0072] 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. ;

[0073] 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. ;

[0074] The zinc catalyst C2 was characterized by nuclear magnetic resonance (NMR), and its 1H NMR spectrum is as follows:

[0075] 1 H-NMR (CDCl3, 400 M-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).

[0076] Example 3

[0077] This embodiment provides a zinc catalyst C3, the preparation process of which includes the following steps:

[0078] 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. ;

[0079] 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. ;

[0080] 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. ;

[0081] 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. ;

[0082] 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. ;

[0083] The zinc catalyst C3 was characterized by nuclear magnetic resonance (NMR), and its 1H NMR spectrum is as follows:

[0084] 1 H-NMR (CDCl3, 400 M-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).

[0085] Example 4

[0086] This embodiment provides a zinc catalyst C4, the preparation process of which includes the following steps:

[0087] 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. ;

[0088] 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. ;

[0089] 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. ;

[0090] 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. ;

[0091] 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. ;

[0092] The zinc catalyst C4 was characterized by nuclear magnetic resonance (NMR), and its 1H NMR spectrum is as follows:

[0093] 1 H-NMR (CDCl3, 400 M-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).

[0094] Example 5

[0095] This embodiment provides a zinc catalyst C5, the preparation process of which includes the following steps:

[0096] 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. ;

[0097] 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. ;

[0098] 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. ;

[0099] 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. ;

[0100] 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. ;

[0101] The zinc catalyst C5 was characterized by nuclear magnetic resonance (NMR), and its 1H NMR spectrum is as follows:

[0102] 1 H-NMR (CDCl3, 400 M-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).

[0103] Example 6

[0104] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0105] 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.

[0106] Example 7

[0107] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0108] 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.

[0109] Example 8

[0110] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0111] 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.

[0112] Example 9

[0113] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0114] 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.

[0115] Example 10

[0116] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0117] 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.

[0118] Example 11

[0119] This embodiment provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0120] 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.

[0121] Example 12

[0122] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0123] 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.

[0124] Example 13

[0125] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0126] 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.

[0127] Example 14

[0128] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0129] 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.

[0130] Example 15

[0131] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0132] 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.

[0133] Example 16

[0134] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0135] 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.

[0136] Example 17

[0137] This embodiment provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0138] 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.

[0139] Comparative Example 1

[0140] This comparative example provides a method for catalytic degradation of anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0141] 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.

[0142] Comparative Example 2

[0143] This comparative example provides a method for regenerating anhydride-cured epoxy resin, the preparation process of which includes the following steps:

[0144] 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.

[0145] Comparative Example 3

[0146] The raw materials used are those in Examples 6-11 or Comparative Example 1: biodegradable anhydride-cured epoxy resin.

[0147] Performance testing:

[0148] The degradation of the degradable anhydride-cured epoxy resins of Examples 6-11 and Comparative Example 1 is shown in Table 1.

[0149] Table 1. Degradation rates of the degradable anhydride-cured epoxy resins of Examples 6-11 and Comparative Example 1.

[0150]

[0151] As shown in Table 1, the biodegradable anhydride-cured epoxy resins of Examples 6-11 of the present invention have high degradation rates.

[0152] 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.

[0153] Glass transition temperature: obtained using a TA-Q200 differential scanning calorimeter manufactured by TA Instruments, USA.

[0154] 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.

[0155] Impact strength: The test was conducted using a Sansi ZBC-50 single-arm pendulum impact tester in accordance with GB / T 1843-2008.

[0156] 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.

[0157] Table 2. Properties of regenerated anhydride-cured epoxy resin.

[0158]

[0159] 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.

[0160] 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): Equation (I), Equation (II); 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.

2. A method for preparing a zinc catalyst, characterized in that, Includes the following steps: S1. Hydroxybenzaldehyde Formaldehyde and an acid catalyst are mixed and reacted to yield substituted hydroxybenzaldehyde. ; S2. Replacement of hydroxybenzaldehyde The reaction with the secondary amine R1R2NH yields a substituted hydroxyketone compound. ; S3. The substituted hydroxyketone compound With alkylamine compounds The reaction yields an imine compound. ; S4. Imine compounds With substituted benzyl alcohols The reaction yields the aminoimine ligand. ; S5. The aminoimine ligand The zinc catalyst of claim 7 is obtained by reacting with zinc acetate. 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.

3. The method for preparing the zinc catalyst according to claim 2, characterized in that, The hydroxybenzaldehyde The molar ratio with formaldehyde is 1:1; And / or, the substituted hydroxybenzaldehyde The molar ratio of the secondary amine R1R2NH to the secondary amine is 0.4~0.7:1; And / or, the substituted hydroxyketone compound With alkylamine compounds The molar ratio is 1:1.05~1.15; And / or, the imine compound With substituted benzyl alcohols The molar ratio is 1:0.3~0.6; And / or, aminoimine ligands The molar ratio with zinc acetate is 1:

1.

4. The method for preparing the 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 methanesulfonic acid.

5. A method for catalytic degradation of anhydride-cured epoxy resin, characterized in that, Includes the following steps: A biodegradable anhydride-cured epoxy resin, the zinc catalyst described in claim 1, and a solvent are mixed and subjected to a degradation reaction to obtain anhydride-cured epoxy resin degradation products.

6. The method for catalytic degradation of epoxy resin cured by acid anhydride according to claim 5, characterized in that, The mass ratio of the biodegradable anhydride-cured epoxy resin to the zinc catalyst is 1:0.005~0.

05.

7. The method for catalytic degradation of epoxy resin cured by acid anhydride according to claim 5, characterized in that, 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 anhydride-cured epoxy resin, characterized in that, Includes the following steps: The degradation product of the anhydride-cured epoxy resin according to any one of claims 5 to 7, the anhydride curing agent and the curing accelerator are mixed and heated to cure, thereby obtaining the regenerated anhydride-cured epoxy resin.

9. The method for regenerating anhydride-cured epoxy resin according to claim 8, characterized in that, The anhydride curing agent is selected from at least one of phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and pyromellitic dianhydride. 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-triazabicyclo[4.4.0]dec-5-ene, 2-mercaptobenzothiazole, 1-cyanoethyl-2-ethyl-4-methylimidazolium, and metal salts of acetylacetone.

10. The method for regenerating anhydride-cured epoxy resin according to claim 9, characterized in that, The mass ratio of the degradation products of the anhydride-cured epoxy resin, the anhydride curing agent, and the curing accelerator is 1:0.6~0.9:0.01~0.03.

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