Degradation, recovery and regeneration method of degradable anhydride cured epoxy resin

Abstract

The invention discloses a degradation, recovery and regeneration method for degradable anhydride cured epoxy resin, and relates to the field of epoxy resin and degradation and regeneration thereof. Various types of salalen ligands are designed and synthesized, the salalen ligands are matched with zinc metal to obtain the zinc catalyst, and the zinc catalyst is used for catalytically degrading the anhydride cured epoxy resin, so that the anhydride cured epoxy resin can be quickly and efficiently degraded under mild conditions; the generated anhydride cured epoxy resin degradation product contains active groups and can be further recycled. After the anhydride cured epoxy resin degradation product is recycled and regenerated, the obtained regenerated anhydride cured epoxy resin is good in mechanical property, the comprehensive performance is slightly different from that of non-degraded anhydride cured epoxy resin, and the recycling value 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 degradable 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, the cured epoxy resin product usually has the problem of being 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 the waste epoxy resin product, but the waste epoxy resin product usually contains 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, and 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 epoxy resin recovered by degradation and regeneration are difficult to restore to the mechanical properties of the anhydride-cured epoxy resin without degradation.

[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, the physical degradation and recycling is to mechanically crush the waste materials and directly use them as fillers, which 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; the thermal energy degradation and recycling is to directly burn the waste materials to obtain heat energy, which usually releases a large amount of toxic gas, pollutes the environment, and endangers human health, and direct burning also causes waste of high-value-added materials; the biological degradation and recycling method is to degrade the resin matrix into small molecular monomers or oligomers under the action of biological catalysts such as enzymes, which has mild conditions and is environmentally friendly, but has low degradation efficiency; the light degradation and recycling method is to decompose the resin matrix under the action of light, which has high degradation efficiency, mild degradation conditions, and environmental protection, but usually needs to add an initiator in the degradation system and has high energy consumption; the chemical degradation and recycling method is to degrade the resin matrix into small molecular monomers or oligomers by chemical methods, which has mild recycling conditions and high recycling rate, and becomes the most commonly used recycling method at present.

[0005] Currently, the chemical degradation recycling method for anhydride-cured epoxy resin usually degrades under acidic or basic conditions, but strong base degradation of the cured epoxy resin usually needs high temperature or high pressure conditions, which has high energy consumption and low utilization degree of the recycled products; the degradation of the cured epoxy resin under acidic conditions can realize low-temperature degradation and low energy consumption, but the acidic solvent can corrode the equipment.

[0006] Therefore, it is an urgent problem to be solved to realize rapid and efficient degradation and recycling of anhydride-cured epoxy resin under mild conditions, and to obtain regenerated epoxy resin with high recycling value. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a degradation and recycling regeneration method of degradable anhydride-cured epoxy resin, wherein a plurality of types of salalen ligands are designed and synthesized, the salalen ligands are combined with zinc metal to obtain a zinc catalyst, the zinc catalyst is used to catalyze the degradation of the anhydride-cured epoxy resin, the rapid and efficient degradation of the anhydride-cured epoxy resin under mild conditions can be realized, the generated anhydride-cured epoxy resin degradation product contains active groups and can be further recycled. After the anhydride-cured epoxy resin degradation product is recycled and regenerated, the regenerated anhydride-cured epoxy resin has good mechanical properties, the comprehensive performance is not much different from that of the anhydride-cured epoxy resin without degradation, and has high recycling value.

[0008] The present application aims to provide a zinc catalyst, the structure of the zinc catalyst is shown in formula (I) or formula (II):

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

[0010] Wherein, X is selected from trifluoromethyl, methoxy, fluorine, chlorine, bromine, cyano or phenoxy; R1, R2 are independently selected from ethyl, propyl, diisopropylamine, phenyl, benzyl or methoxy(methyl)amine; R3, R4 are independently selected from methyl or methoxy.

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

[0012] S1. mixing hydroxybenzaldehyde , formaldehyde and an acid catalyst, reacting to obtain substituted hydroxybenzaldehyde ;

[0013] S2. reacting the substituted hydroxybenzaldehyde with a secondary amine R1R2NH to obtain a substituted hydroxyketone compound ;

[0014] S3. reacting the substituted hydroxyketone compound with an alkylamine compound to give an imine compound ;

[0015] S4. reacting the imine compound with a substituted benzyl alcohol to give an amino imine ligand ;

[0016] S5. reacting the amino imine ligand with zinc acetate to give the zinc catalyst;

[0017] wherein X is selected from trifluoromethyl, methoxy, fluorine, chlorine, bromine, cyano or phenoxy; R1, R2are independently selected from ethyl, propyl, diisopropylamine, phenyl, benzyl or methoxy(methyl)amine; R3, R4are independently selected from methyl or methoxy; R5, R6are selected from H or R5, R6form an alkyl six-membered ring.

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

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

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

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

[0022] In some embodiments of the present application, in S2, the molar ratio of the substituted hydroxybenzaldehyde to the secondary amine R1R2NH is 0.3-0.6:1.

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

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

[0025] In some embodiments of the present application, in S2, the solvent for the reaction is mesitylene.

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

[0027] In some embodiments of the present application, in S3, the molar ratio of the substituted hydroxyketone compound The molar ratio of the alkyl amine compound to the substituted benzyl alcohol is 1:0.5-0.8.

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

[0029] In some embodiments of the present application, in S3, the temperature for the reaction is room temperature, and the time is 3-6 hours.

[0030] In some embodiments of the present application, in S4, the molar ratio of the imine compound to the substituted benzyl alcohol is 1:0.5-0.8. In some embodiments of the present application, in S4, the catalyst used for the reaction is aluminum trichloride.

[0031] In some embodiments of the present application, in S4, the molar ratio of the imine compound to aluminum trichloride is 1:1.

[0032] In some embodiments of the present application, in S4, the solvent for the reaction is m-trimethylbenzene.

[0033] In some embodiments of the present application, in S4, the temperature for the reaction is 150-190°C, and the time is 4-8 hours.

[0034] In some embodiments of the present application, in S5, the molar ratio of the amino imine ligand

[0035] to zinc acetate is 1:1. In some embodiments of the present application, in S5, the solvent for the reaction is toluene.

[0036] In some embodiments of the present application, in S5, the temperature for the reaction is -78-25°C, and the time is 24-48 hours.

[0037] Another object of the present application is to provide a method for catalytically degrading anhydride-cured epoxy resin, comprising the following steps:

[0038] Mixing the degradable anhydride-cured epoxy resin, the zinc catalyst and the solvent, and degrading the reaction to obtain an anhydride-cured epoxy resin degradation product.

[0039] In some embodiments of the present application, the mass ratio of the degradable anhydride-cured epoxy resin to the zinc catalyst is 1:0.01-0.04.

[0040] In some embodiments of the present application, the temperature for the degradation reaction is 50-80°C, and the time is 5-10 hours.

[0041]

[0042] ​In some embodiments of the present application, 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, carbon tetrachloride.

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

[0044] In some embodiments of the present application, the anhydride curing agent is selected from at least one of phthalic anhydride, hexahydrophthalic anhydride, tetrahydrophthalic anhydride, methyl tetrahydrophthalic anhydride, dodecenyl succinic anhydride, methyl hexahydrophthalic anhydride, maleic anhydride, pyromellitic dianhydride.

[0045] In some embodiments of the present application, 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-methylimidazole, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, 2-mercaptobenzothiazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, acetylacetone metal salt.

[0046] In some embodiments of the present application, 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.

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

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

[0049] (1) The present application designs and synthesizes various types of salalen ligands, which are combined with zinc metal to obtain a zinc catalyst. The zinc catalyst has good stability, has a lewis acid metal zinc ion, and introduces a Lewis basic tertiary amine group on the side arm. The lewis acid metal zinc ion can catalyze the activation of an ester group, and the tertiary amine group can activate a nucleophile. The zinc catalyst is used for degrading an epoxy resin, which can realize rapid and efficient degradation of the epoxy resin under mild conditions.

[0050] (2) The zinc catalyst of the present application introduces nitrogen-containing basic groups in the structure of the zinc catalyst, so that the zinc catalyst can activate the nucleophile, and meanwhile, the coordination with the metal zinc does not weaken the Lewis acidity of the metal center, so that the metal zinc center has a certain openness and sufficient space to activate the ester group, but the space of the metal zinc center is not too open, thereby ensuring the high stability of the metal zinc center.

[0051] (3) The method for degrading the acid anhydride-cured epoxy resin of the present application can realize rapid and efficient degradation of the epoxy resin under mild conditions, and the degradation product contains active groups and can be further recycled.

[0052] (4) The regenerated acid anhydride-cured epoxy resin of the present application has good mechanical properties, and the comprehensive performance is not much different from that of the acid anhydride-cured epoxy resin without degradation, and has high recycling value. DETAILED DESCRIPTION

[0053] In order to enable the person skilled in the art to better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in combination with the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the scope of protection of the present application.

[0054] The degradable acid anhydride-cured epoxy resin is a conventional commercially available product.

[0055] The degradation of the degradable acid anhydride-cured epoxy resin of the present application is as follows:

[0056] .

[0057] The preparation process of the zinc catalyst of the present application is as follows:

[0058] .

[0059] Example 1

[0060] The present embodiment provides a zinc catalyst C1, and the preparation process thereof comprises the following steps:

[0061] S1. Mix hydroxybenzaldehyde (5 mol), formaldehyde (5 mol), concentrated sulfuric acid (0.8 mol) and dichloromethane (100 ml), and react at 35℃ for 9 hours. After the reaction is completed, pass the mixture through a silica gel column with a volume ratio of ethyl acetate to petroleum ether of 1:9, collect the product, remove the solvent by rotary evaporation, and dry to obtain the substituted hydroxybenzaldehyde . ;

[0062] S2. Substituted hydroxybenzaldehyde S2. Substituted hydroxybenzaldehyde ;

[0063] S3. Substituted hydroxyketone compound S3. Substituted hydroxyketone compound ;

[0064] S4. Imine compound S4. Imine compound ;

[0065] S5. Zinc catalyst C1 S5. Zinc catalyst C1 ;

[0066] The NMR hydrogen spectrum of zinc catalyst C1 is as follows:

[0067] 1 H-NMR (CDCI3, 400 M-Hz), δ ​​(ppm):8.24(s,1H,CH), 7.85(s,1H,Ph), 7.36(s,1H,Ph), 6.48(s,1H,Ph), 6.37(s,1H,Ph), 3.83(s,3H,CH3), 3.80(s,3H,CH3), 3.71(s,2H,CH2), 3.62(s,2H,CH2), 3.04(m,1H,CH), 2.61(m,1H,CH), 2.46(t,4H,CH2), 2.28(s,3H,CH3), 2.19-1.94(m,2H,CH2), 1.66-1.10(m,10H,CH2), 0.88(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 35 °C for 9 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 substituted hydroxybenzaldehyde. ;

[0071] S2. Replacement of hydroxybenzaldehyde A mixture of 5 mol of diisopropylamine, 10 mol of aluminum trichloride, and 150 ml of m-trimethylbenzene was prepared and reacted at 165 °C for 6 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 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 4 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 1:12 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), aluminium trichloride (10 mol) and mesitylene (150 ml) were mixed and reacted at 165 °C for 6 hours. After the reaction was completed, ethyl acetate: petroleum ether = 1:10 (volume ratio) was passed through a silica gel column to collect the product. The solvent was removed by rotary evaporation and dried to obtain the amino imine ligand ;

[0074] S5. The amino imine ligand (5 mol) was dissolved in 150 ml of toluene, zinc acetate (5 mol) dissolved in toluene was added at -78 °C, and the temperature was raised to room temperature. The reaction was carried out for 28 hours. After the reaction was completed, the solvent was removed by rotary evaporation, recrystallized with n-hexane, filtered, the solvent was removed by rotary evaporation, and dried to obtain the zinc catalyst C2 ;

[0075] The zinc catalyst C2 was characterized by nuclear magnetic resonance. The hydrogen spectrum of the nuclear magnetic resonance is as follows:

[0076] 1 H-NMR (CDC13, 400 M-Hz), δ (ppm): 8.10 (s, 1H, CH), 7.18 (s, 1H, Ph), 6.88-6.87 (s, 2H, Ph), 6.81 (s, 1H, Ph), 3.81 (s, 3H, OCH3), 3.65-3.62 (m, 6H, CH2), 2.72-2.69 (m, 4H, CH2), 2.27 (s, 3H, CH3), 2.19 (s, 3H, CH3), 2.17 (s, 3H, CH3), 0.99 (d, 12H, CH3).

[0077] Example 3

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

[0079] S1. Substituted hydroxybenzaldehyde (5 mol), formaldehyde (5 mol), concentrated sulfuric acid (0.8 mol) and dichloromethane (100 ml) were mixed and reacted at 35 °C for 9 hours. After the reaction was completed, ethyl acetate: petroleum ether = 1:9 (volume ratio) was passed through a silica gel column to collect the product. The solvent was removed by rotary evaporation and dried to obtain the substituted hydroxybenzaldehyde ;

[0080] S2. The substituted hydroxybenzaldehyde (5 mol), dibenzyl alcohol (10 mol), aluminium trichloride (10 mol) and mesitylene (150 ml) were mixed and reacted at 165 °C for 6 hours. After the reaction was completed, ethyl acetate: petroleum ether = 1:10 (volume ratio) was passed through a silica gel column to collect the product. The solvent was removed by rotary evaporation and dried to obtain the substituted hydroxyketone compound ;

[0081] S3. Substituted hydroxy ketone compound (5 mol), alkyl amine compound (5.5 mol) and n-hexane (150 ml) were mixed and stirred at room temperature for 4 hours. After the reaction was completed, anhydrous MgS04was added to remove water, filtered, and passed through a silica gel column with ethyl acetate:n-hexane (1:12) to collect the product. The solvent was removed by rotary evaporation, and dried to obtain the imine compound ;

[0082] S4. Imine compound (10 mol), substituted benzyl alcohol (5 mol), aluminum chloride (10 mol) and m-xylene (150 ml) were mixed and reacted at 165°C for 6 hours. After the reaction was completed, the product was collected by passing through a silica gel column with ethyl acetate: petroleum ether (1:10), the solvent was removed by rotary evaporation, and dried to obtain the amino imine ligand ;

[0083] S5. The amino imine ligand (5 mol) was dissolved in 150 ml of toluene, and zinc acetate (5 mol) dissolved in toluene was added at -78°C. The temperature was raised to room temperature, and reacted for 28 hours. After the reaction was completed, the solvent was removed by rotary evaporation, recrystallized with n-hexane, filtered, the solvent was removed by rotary evaporation, and dried to obtain the zinc catalyst C3 ;

[0084] The zinc catalyst C3was characterized by nuclear magnetic resonance, and the nuclear magnetic resonance spectrum of hydrogen was as follows:

[0085] 1 H-NMR (CDC13, 400 M-Hz), δ (ppm): 8.20 (s, 1H, CH), 7.57 (s, 1H, Ph), 7.31-7.21 (m, 11H, Ph), 6.48 (s, 1H, Ph), 6.37 (s, 1H, Ph), 3.83 (s, 3H, CH3), 3.80 (s, 3H, CH3), 3.66 (s, 6H, CH2), 2.61 (s, 2H, CH2), 3.03 (m, 1H, CH), 2.59 (m, 1H, CH), 2.26 (s, 3H, CH3), 2.20-1.95 (s, 2H, CH2), 1.65-1.11 (m, 6H, CH2).

[0086] Example 4

[0087] This example 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 35 °C for 9 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 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 reacted at 165 °C for 6 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 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 4 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 1:12 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 A mixture of 5 mol of aluminum trichloride (10 mol) and 150 ml of m-trimethylbenzene was reacted at 165 °C for 6 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 28 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, 400 M-Hz), δ(ppm):8.11(s,1H,CH), 7.59(s,1H,Ph), 7.30-7.20(m,11H,Ph), 6.88(s,1H,Ph), 6.81(s,1H,Ph), 3.66-3.62(m,10H,CH2), 2.72(s,2H,CH2),2.27(s,3H,CH3), 2.18(s,3H,CH3), 2.14(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 35 °C for 9 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 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 6 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 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 4 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 1:12 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 A mixture of 5 mol of aluminum trichloride (10 mol) and 150 ml of m-trimethylbenzene was reacted at 165 °C for 6 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 temperature was raised to room temperature and the reaction was allowed to proceed for 28 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 the zinc catalyst C5. ;

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

[0103] 1 H-NMR (CDCl3, 400 M-Hz), δ (ppm):8.23(s,1H,Ph), 7.42(d,2H,Ph), 7.23-7.17(m,2H,Ph), 7.06(d,2H,Ph), 6.93(s,1H,Ph), 6.49(s,1H,Ph), 6.38(s,1H,Ph), 3.84(s,3H,OCH3), 3.80(s,5H,CH2 and OCH3), 3.61(s,2H,CH2), 3.57(s,3H,CH3), 3.03(m,1H,CH), 2.61(m,1H,CH), 2.46(s,3H,CH3), 2.27(s,3H,CH3), 2.19-1.94(m,2H,CH2),1.66-1.10(m,6H,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] The degradable anhydride-cured epoxy resin (100 g), zinc catalyst C1 (5 g) and dichloromethane (200 g) were mixed, and the mixture was subjected to degradation reaction 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 concentrated solution was added dropwise into n-hexane to precipitate, and the precipitate was dried to obtain an anhydride-cured epoxy resin degradation product A2. After the reaction was completed, the undegraded anhydride-cured epoxy resin was removed, and then washed with ethyl acetate and acetone in sequence. After drying, the weight of the undegraded anhydride-cured epoxy resin was measured, and the degradation rate of the degradable anhydride-cured epoxy resin was calculated.

[0110] Example 8

[0111] The present example provides a method for catalyzing degradation of an anhydride-cured epoxy resin, and the preparation process thereof comprises the following steps:

[0112] The degradable anhydride-cured epoxy resin (100 g), zinc catalyst C2 (0.5 g) and dichloromethane (100 g) were mixed, and the mixture was subjected to degradation reaction 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 concentrated solution was added dropwise into n-hexane to precipitate, and the precipitate was dried to obtain an anhydride-cured epoxy resin degradation product A3. After the reaction was completed, the undegraded anhydride-cured epoxy resin was removed, and then washed with ethyl acetate and acetone in sequence. After drying, the weight of the undegraded anhydride-cured epoxy resin was measured, and the degradation rate of the degradable anhydride-cured epoxy resin was calculated.

[0113] Example 9

[0114] The present example provides a method for catalyzing degradation of an anhydride-cured epoxy resin, and the preparation process thereof comprises the following steps:

[0115] The degradable anhydride-cured epoxy resin (100 g), zinc catalyst C3 (0.5 g) and dichloromethane (100 g) were mixed, and the mixture was subjected to degradation reaction 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 concentrated solution was added dropwise into n-hexane to precipitate, and the precipitate was dried to obtain an anhydride-cured epoxy resin degradation product A4. After the reaction was completed, the undegraded anhydride-cured epoxy resin was removed, and then washed with ethyl acetate and acetone in sequence. After drying, the weight of the undegraded anhydride-cured epoxy resin was measured, and the degradation rate of the degradable anhydride-cured epoxy resin was calculated.

[0116] Example 10

[0117] The present example provides a method for catalyzing degradation of an anhydride-cured epoxy resin, and the preparation process thereof comprises the following steps:

[0118] The degradable anhydride-cured epoxy resin (100 g), zinc catalyst C4 (0.5 g) and dichloromethane (100 g) were mixed, and the mixture was subjected to degradation reaction at 80°C for 5 hours. After cooling to room temperature, the un-degraded anhydride-cured epoxy resin was removed by filtration. The filtrate was concentrated under reduced pressure to remove dichloromethane. The concentrated solution was added dropwise into n-hexane to precipitate, and the precipitate was dried to obtain an anhydride-cured epoxy resin degradation product A5. After the reaction was completed, the un-degraded anhydride-cured epoxy resin was taken out, washed with ethyl acetate and acetone in sequence, and dried to calculate the degradation rate of the degradable anhydride-cured epoxy resin.

[0119] Example 11

[0120] The present example provides a method for catalytically degrading an anhydride-cured epoxy resin, which comprises the following steps:

[0121] The degradable anhydride-cured epoxy resin (100 g), zinc catalyst C5 (0.5 g) and dichloromethane (100 g) were mixed, and the mixture was subjected to degradation reaction at 80°C for 5 hours. After cooling to room temperature, the un-degraded anhydride-cured epoxy resin was removed by filtration. The filtrate was concentrated under reduced pressure to remove dichloromethane. The concentrated solution was added dropwise into n-hexane to precipitate, and the precipitate was dried to obtain an anhydride-cured epoxy resin degradation product A6. After the reaction was completed, the un-degraded anhydride-cured epoxy resin was taken out, washed with ethyl acetate and acetone in sequence, and dried to calculate the degradation rate of the degradable anhydride-cured epoxy resin.

[0122] Example 12

[0123] The present example provides a method for regenerating an anhydride-cured epoxy resin, which comprises the following steps:

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

[0125] Example 13

[0126] The present example provides a method for regenerating an anhydride-cured epoxy resin, which comprises the following steps:

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

[0128] Example 14

[0129] The embodiment provides a regeneration method of an anhydride-cured epoxy resin, and the preparation process comprises the following steps:

[0130] Anhydride-cured epoxy resin degradation product A3 (100 g), tetrahydrophthalic anhydride (70 g) and benzyldimethylamine (2 g) are added into a reactor, heated to 110 DEG C, and heated and cured for 20 min to obtain regenerated anhydride-cured epoxy resin B3.

[0131] Example 15

[0132] The embodiment provides a regeneration method of an anhydride-cured epoxy resin, and the preparation process comprises the following steps:

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

[0134] Example 16

[0135] The embodiment provides a regeneration method of an anhydride-cured epoxy resin, and the preparation process comprises the following steps:

[0136] Anhydride-cured epoxy resin degradation product A5 (100 g), methylhexahydrophthalic anhydride (85 g) and 2-ethyl-4-methylimidazole (2.5 g) are added into a reactor, heated to 100 DEG C, and heated and cured for 35 min to obtain regenerated anhydride-cured epoxy resin B5.

[0137] Example 17

[0138] The embodiment provides a regeneration method of an anhydride-cured epoxy resin, and the preparation process comprises the following steps:

[0139] Anhydride-cured epoxy resin degradation product A6 (100 g), pyromellitic dianhydride (65 g) and 2-mercaptobenzothiazole (2 g) are added into a reactor, heated to 105 DEG C, and heated and cured for 30 min to obtain regenerated anhydride-cured epoxy resin B6.

[0140] Comparative Example 1

[0141] The comparative example provides a method for catalyzing anhydride-cured epoxy resin degradation, and the preparation process comprises the following steps:

[0142] The degradable anhydride-cured epoxy resin (10 g) and the aqueous sodium hydroxide solution (83.3 g) with a mass percentage concentration of 10 wt% were added into a reactor, and the temperature was raised to 80 ℃. The reaction was heated for 8 hours. After the temperature was lowered to room temperature, the anhydride-cured epoxy resin that was not degraded was removed by filtration. The filtrate was neutralized by acetic acid, concentrated under reduced pressure to remove water, and dropped into n-hexane for precipitation. The precipitate was dried to obtain the anhydride-cured epoxy resin degradation product A7. The anhydride-cured epoxy resin that was not degraded was taken out after the reaction, washed with ethyl acetate and acetone in sequence, dried, and weighed to calculate the degradation rate of the degradable anhydride-cured epoxy resin.

[0143] Comparative Example 2

[0144] The present comparative example provides a regeneration method of an anhydride-cured epoxy resin, and the preparation process comprises the following steps:

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

[0146] Comparative Example 3

[0147] The raw materials in Examples 6-11 or Comparative Example 1 were used: the degradable anhydride-cured epoxy resin.

[0148] Performance test:

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

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

[0151]

[0152] As shown in Table 1, the degradation rate of the degradable anhydride-cured epoxy resin in Examples 6-11 of the present application is high.

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

[0154] Glass transition temperature: tested by a TA-Q200 differential scanning calorimeter produced by TA Instruments, USA.

[0155] Flexural strength and flexural modulus: tested according to ISO 178 standard, sample size 80 mm x 10 mm x 4 mm, and test rate 2 mm / min.

[0156] Impact strength: tested according to GB / T 1843-2008 using Sansi ZBC-50 single arm pendulum impact tester.

[0157] Tensile strength, tensile modulus, elongation at break: the recycled anhydride cured epoxy resin of Examples 12-17, Comparative Example 2 or the degradable anhydride cured epoxy resin of Comparative Example 3 were cast into dumbbell-shaped molds, cured and demolded, and the surface was polished to obtain 4mm thick standard samples, and the tensile properties were tested at a tensile rate of 5mm / min according to ISO527 standard.

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

[0159]

[0160] As can be seen from Table 2, after the anhydride cured epoxy resin degradation products of Examples 5-11 were recycled, although the elongation at break, bending strength and impact strength were reduced, the glass transition temperature, tensile strength, tensile modulus and bending modulus were improved, and the comprehensive performance was not much different from that of the degradable anhydride cured epoxy resin without treatment, indicating that the degradable anhydride cured epoxy resin of the present application has high recycling value after degradation.

[0161] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and not to limit it, although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that the technical personnel can still modify or replace the specific embodiments of the present application after reading the present application, but these modifications or changes are still within the scope of the present application. The claims of the present application.

Claims

1. A zinc catalyst, characterized in that, The structure of the zinc catalyst is shown as formula (I) or formula (II): Formula (I), Formula (II); Wherein, X is selected from trifluoromethyl, methoxy, fluorine, chlorine, bromine, cyano or phenoxy; R1, R2 are independently selected from ethyl, propyl, diisopropylamine, 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 trifluoromethyl, methoxy, fluorine, chlorine, bromine, cyano or phenoxy; R1, R2 are independently selected from ethyl, propyl, diisopropylamine, 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 0.3 to 0.6 : 1; and / or, the substituted hydroxyketone compound with an alkyl amine compound at a molar ratio of 1 : 1.1 ~ 1.2; and / or the imine compound with a substituted benzyl alcohol in a molar ratio of 1 :0.5-0.8; 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 a catalytically degradable anhydride-cured epoxy resin degradation, characterized by, 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 catalytically degrading an anhydride-cured epoxy resin according to claim 5, wherein, The mass ratio of the degradable anhydride-cured epoxy resin to the zinc catalyst is 1:0.01-0.

04.

7. The method of catalytically degrading an anhydride-cured epoxy resin according to claim 5, wherein, 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: mixing the anhydride-cured epoxy resin degradation product according to any one of claims 5-7, an anhydride curing agent and a curing accelerator, and heating and curing 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, dodecenyl succinic anhydride, methyl hexahydrophthalic anhydride, maleic 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 8, 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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