Epoxy hardener containing double dynamic bonds, preparation method of epoxy hardener, degradable and reconfigurable epoxy resin material and preparation method of degradable and reconfigurable epoxy resin material

Abstract

The invention belongs to the technical field of epoxy resin, and discloses an epoxy curing agent containing double dynamic bonds, a preparation method of the epoxy curing agent, a degradable and reconfigurable epoxy resin material and a preparation method of the degradable and reconfigurable epoxy resin material. Mixing and reacting with a solution containing organic acid and an M2 compound solution containing carbonyl, ether bonds or aldehyde groups to obtain a uniform solution; and adding an alkali solution into the solution, extracting, desolventizing and deprotecting the solution, adding a dialdehyde M3 compound solution, reacting, and drying to obtain the epoxy curing agent containing the double dynamic bonds. The degradable and reconfigurable epoxy resin material is prepared by compounding the modified epoxy resin with epoxy resin and carrying out a thermocuring process, the material can be quickly degraded in weak acid at a lower temperature, the material can be reconfigured at a certain temperature, the preparation process is simple, the required raw materials are wide in source and low in price, and the method is suitable for industrial production. The method has good economical efficiency and application value.

Description

Technical Field

[0001] The present invention relates to the fields of curing agents and epoxy resins, and relates to an epoxy curing agent containing dual dynamic bonds, a preparation method thereof, a degradable and reconstructable epoxy resin material, and a preparation method thereof. Background Art

[0002] Epoxy resin materials are a type of polymer materials formed by curing epoxy resins and curing agents through thermal curing, which have the characteristics of high mechanical properties, excellent adhesion properties, good insulation, corrosion resistance, stability, and heat resistance. They are widely used in the fields of wind power, automobiles, chemical engineering, light industry, electronic appliances, and aerospace. With the continuous development of society, epoxy resin materials have become one of the most indispensable materials in the development of the national economy, and their output and application level can even reflect the degree of development of a country's industrial technology from one aspect.

[0003] However, with the increasing use of epoxy resin materials, the treatment problem of retired materials has attracted more and more attention. Traditional epoxy resin materials are all thermosetting materials with high crosslinking density. Once thermoset, they cannot be processed again, and currently, recycling can basically only be carried out by heat treatment and mechanical crushing methods. This not only causes great pollution to the environment but also results in waste of resources, and limits the application scenarios of epoxy resin materials.

[0004] Therefore, in recent years, the recycling of epoxy resin materials has become an increasingly popular research direction. Generally speaking, there are mainly three ways to achieve the degradation and reconstruction of epoxy resin materials at present: 1. For traditional epoxy resin systems, some strong acids, Lewis acids, metal catalysts, or supercritical fluids can be used to degrade the cured epoxy resin materials under high temperature and high pressure into small molecule substances. However, these methods often have extreme implementation conditions, low utilization rate of degradation products, and will generate new pollutants; 2. Introduce dynamic bonds into the epoxy resin structure. This method utilizes the reversibility of dynamic bonds and the principle of weak bond energy, making the epoxy resin itself have dynamics, and its structure can break under specific conditions to achieve the degradation effect. However, the epoxy resin formed by this method often has specific properties, which will bring problems of limited performance adjustment degree and narrow application scenarios; 3. Introduce dynamic bonds into the epoxy resin curing agent structure. This method also utilizes the reversibility of dynamic bonds and the principle of weak bond energy. The difference is that the dynamic bonds are introduced into the curing agent rather than the epoxy resin itself. Such a design can apply the epoxy resin curing agent with dynamic bonds to different epoxy resin systems, greatly ensuring the flexibility of the formulation. This is also a currently more concerned method.

[0005] At present, there are mainly the following methods to introduce dynamic bonds into epoxy curing agents to achieve the degradation and reconstitution of epoxy resins: 1. Prepare curing agents containing ester bonds. This method utilizes the principle that ester bonds are unstable under alkaline conditions to achieve the degradation of epoxy resins, and uses the method of adding transesterifying agents to achieve the reconstitution of epoxy resin materials. However, the disadvantages of this method are that strong alkali solutions are required, the degradation time is long, and the reconstitution temperature is high; 2. Prepare curing agents containing acetal and ketal structures. This method utilizes the principle that acetal and ketal bonds are unstable under acidic conditions to achieve the degradation of epoxy resins. However, the reconstitution performance of epoxy resin materials cured with this curing agent is poor and cannot be secondarily formed. Patent US20190016667A1 discloses a synthesis method of diaminoacetal and diamino ketal; 3. Prepare curing agents containing imine structures. Imine is a class of substances containing C=N. Epoxy resin materials cured with curing agents containing imine structures can not only have certain response stimuli under acidic conditions, can move and degrade, and can also undergo metathesis reactions with amine substances. And substances containing imine structures are also relatively easy to achieve reconstitution at high temperatures. However, the viscosity of imine curing is often too large, which is not conducive to process operation. And according to the author's practical verification, the degradation ability of materials cured by low-viscosity imine curing agents with epoxy resins is often insufficient under mild conditions. And if you want the imine curing agent / epoxy system to have good degradability, it often requires adding a curing agent far higher than the theoretical value, which will affect the overall processability of the system, etc.; 4. Prepare curing agents containing disulfide bond structures. Disulfide bonds can undergo rapid exchange between disulfides (RSSR) or between disulfides and thiolates (RS-), and will be stimulated by various external stimuli, such as sound, light, heat and mechanical energy, etc. However, curing agents containing disulfide bonds are often solids with high activity, which affects their use processability, and the synthesis cost of disulfide bond curing agents is relatively high and not economical. Summary of the Invention

[0006] In order to solve the problems of poor degradation performance and reconstitution performance of epoxy resin materials under mild conditions in the prior art, the purpose of the present invention is to propose an epoxy curing agent containing dual dynamic bonds, its preparation method, and a degradable and reconstitutable epoxy resin material and its preparation method. By synthesizing a diamino epoxy curing agent containing both acetal (ketal) and imine structures, dual dynamic bonds are introduced into the epoxy resin system during the curing process, so as to endow the epoxy resin material with excellent degradation performance and reconstitution performance under mild conditions while ensuring the processability of the epoxy resin system.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] An epoxy curing agent containing dual dynamic bonds, the general molecular structure formula of the epoxy curing agent is:

[0009]

[0010] In the general formula of the molecular structure, R is a straight-chain alkyl group, a branched-chain alkyl group with a branch, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an aromatic group, a heteroaromatic group, a hydrocarbonylene group or a hydrocarbon hetero-hydrocarbonylene group;

[0011] In the general formula of the molecular structure, R 1 is a hydrogen atom, a straight-chain alkyl group, a branched-chain alkyl group with a branch, a cycloalkyl group, a heterocyclic group, an alkenyl group, an aromatic group or a heteroaromatic group;

[0012] In the general formula of the molecular structure, R 2 is a hydrogen atom, a straight-chain alkyl group, a branched-chain alkyl group with a branch, a cycloalkyl group, a heterocyclic group, an alkenyl group, an aromatic group or a heteroaromatic group;

[0013] In the general formula of the molecular structure, R 3 is a straight-chain alkyl group, a branched-chain alkyl group with a branch, a cycloalkyl group, a heterocyclic group, an aromatic group, a heteroaromatic group, a hydrocarbonylene group or a hydrocarbon hetero-hydrocarbonylene group.

[0014] Further, R is

[0015] Further, R 1 is H, ·CH3,

[0016] Further, R 2 is H, ·CH3,

[0017] Further,

[0018] A preparation method of an epoxy curing agent containing double dynamic bonds, comprising the following steps:

[0019] React a compound M containing amino and hydroxyl groups with an amino protecting reagent, then mix it with a solution of an organic acid and a solution of a compound M containing a carbonyl group, an ether bond or an aldehyde group, and react at 10 - 100 °C for 2 - 48 h to obtain a homogeneous solution; 1 2

[0020] Add an alkali solution to the homogeneous solution to quench the organic acid, then perform extraction, solvent removal and deprotection to obtain a homogeneous liquid or solid;

[0021] Add a solution of a dialdehyde compound M 3 to the homogeneous liquid solution or solid solution, react at 10 - 100 °C for 1 - 48 h to obtain a yellow solution, and dry it to obtain an epoxy curing agent containing double dynamic bonds.

[0022] Further, M 1 ​​The general formula of the compound is: In the formula, R is a straight-chain alkyl group, a branched-chain alkyl group with a branch, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an aromatic group, a heteroaromatic group, a hydrocarbonylene group or a hydrocarbon hetero-hydrocarbonylene group.

[0023] Furthermore, the organic acid is acetic acid, p-toluenesulfonic acid, benzoic acid, terephthalic acid or citric acid;

[0024] M 1 The compound is 2-amino-1-butanol, 2-amino-2-methyl-1-propanol, DL-aminopropanol, ethanolamine, p-aminophenol, 4-aminocyclohexanol, 4-aminopyridin-3-ol or L-tryptophanol.

[0025] Furthermore, M containing an amino group and a hydroxyl group 1 The solvent in the solution of the compound and the organic acid is ethyl acetate, dichloromethane, tetrahydrofuran or N,N-dimethylformamide.

[0026] Furthermore, M 2 The general formula of the compound is:

[0027] In the formula, R 1 , R 2 is a hydrogen atom, a straight-chain alkyl group, a branched-chain alkyl group with a branch, a cycloalkyl group, a heterocyclic group, an alkenyl group, an aromatic group or a heteroaromatic group;

[0028] M 3 The general formula of the compound is:

[0029] In the formula, R 3 is a straight-chain alkyl group, a branched-chain alkyl group with a branch, a cycloalkyl group, a heterocyclic group, an aromatic group, a heteroaromatic group, a hydrocarbonylene group or a hydrocarbon hetero-hydrocarbonylene group.

[0030] Furthermore, M 2 The compound is 2-methoxypropene, benzaldehyde, cyclohexanecarbaldehyde, cinnamaldehyde or 6-methylpyridine-2-carbaldehyde;

[0031] M 3 The compound is terephthalaldehyde, isophthalaldehyde, adipaldehyde, cyclohexane-1,4-dicarbaldehyde or [3,3'-bipyridine]-6,6'-dicarbaldehyde;

[0032] M containing a carbonyl group, an ether bond or an aldehyde group 2 The solvent in the compound solution is toluene, xylene, ethanol, methanol, ethyl acetate or dichloromethane.

[0033] Furthermore, the amino protecting reagent is N-ethoxycarbonylphthalimide;

[0034] M containing an amino group and a hydroxyl group1 The molar ratio of the compound to the amino protecting reagent is 0.001 - 10:0.001 - 10;

[0035] M containing amino and hydroxyl groups 1 The compound, M containing carbonyl, ether bond or aldehyde group 2 The compound and M of dialdehyde 3 The molar ratio of the compound is 0.001 - 10:0.001 - 10:0.001 - 10.

[0036] A preparation method of a degradable and reconstructable epoxy resin material, comprising the following steps:

[0037] A mixture of the epoxy curing agent containing dual dynamic bonds as described in claim 1 and epoxy resin with a mass ratio of 0.1 - 10:1 is heated at 60 - 180 °C for 2 - 48 h for thermal curing to obtain a degradable and reconstructable epoxy resin material.

[0038] A degradable and reconstructable epoxy resin material.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] The present invention first prepares a diamine epoxy resin curing agent containing both acetal (ketal) structure and imine structure by using the reactions of hydroxyl - aldehyde group and amino - aldehyde group, and then compound it with epoxy resin. Through a thermal curing process, a degradable and reconstructable epoxy resin material is prepared. This material can be rapidly degraded under weak acid and relatively low temperature conditions, and can be reconstructed at a certain temperature, solving the problems of difficult degradation and inability to be re - formed of traditional epoxy resin materials. Moreover, the preparation process is simple, the required raw materials are widely sourced and inexpensive, having good economic efficiency and application value. The specific advantages are as follows:

[0041] (1) Compared with traditional epoxy resins, the epoxy curing agent containing dual dynamic bonds prepared in the present invention and the degradable and reconstructable epoxy resin have the same operation process and similar curing process, without the need for special process forming requirements. At the same time, they also have the properties of degradability and reconstructability, having the potential to replace traditional epoxy resin materials;

[0042] (2) Compared with the existing degradable or reconstructable epoxy resin materials, the degradable and reconstructable epoxy resin material prepared by using the epoxy curing agent containing dual dynamic bonds prepared in the present invention, due to the simultaneous introduction of acetal (ketal) structure and imine structure, has mild degradation conditions, without the need for special conditions such as high temperature, high pressure, strong acid or strong base, and can be rapidly degraded in weak acid at relatively low temperature, providing the possibility for the degradation of epoxy resin - based components;

[0043] (3) Compared with the existing degradable or reconfigurable epoxy resin materials, the degradable and reconfigurable epoxy resin materials prepared with the dual-dynamic bond-containing epoxy curing agent of the present invention have the ability of secondary processing while ensuring processability and degradability, reducing the waste of raw materials and alleviating environmental pollution;

[0044] (4) The preparation method of the dual-dynamic bond-containing epoxy curing agent and the degradable and reconfigurable epoxy resin of the present invention has the advantages of simple preparation process, convenient operation, low raw material price, wide raw material sources, etc., which is conducive to industrial production. Description of the Drawings

[0045] Figure 1 Schematic diagram of the degradation performance of the degradable and reconfigurable epoxy resin material 1; among them, (a) is before degradation, and (b) is after degradation;

[0046] Figure 2 Schematic diagram of the degradation performance of the degradable and reconfigurable epoxy resin material 2; among them, (a) is before degradation, and (b) is after degradation;

[0047] Figure 3 Schematic diagram of the degradation performance of the comparative epoxy resin material 1; among them, (a) is before degradation, and (b) is after degradation;

[0048] Figure 4 Schematic diagram of the degradation performance of the comparative epoxy resin material 2; among them, (a) is before degradation, and (b) is after degradation;

[0049] Figure 5 Schematic diagram of the degradation performance of the comparative epoxy resin material 3; among them, (a) is before degradation, and (b) is after degradation;

[0050] Figure 6 Schematic diagram of the reconfiguration performance of the degradable and reconfigurable epoxy resin material 1; among them, (a) is before reconfiguration, and (b) is after reconfiguration;

[0051] Figure 7 Schematic diagram of the reconfiguration performance of the degradable and reconfigurable epoxy resin material 2; among them, (a) is before reconfiguration, and (b) is after reconfiguration;

[0052] Figure 8 Schematic diagram of the reconfiguration performance of the comparative epoxy resin material 1; among them, (a) is before reconfiguration, and (b) is after reconfiguration;

[0053] Figure 9 Schematic diagram of the reconfiguration performance of the comparative epoxy resin material 2; among them, (a) is before reconfiguration, and (b) is after reconfiguration;

[0054] Figure 10Schematic diagram of the restructuring performance of comparative epoxy resin material 3; among them, (a) is before restructuring, and (b) is after restructuring;

[0055] Figure 11 DSC curves of degradable and reconstructable epoxy resin materials 1, 2, and 3;

[0056] Figure 12 DSC curves of comparative epoxy resin materials 1, 2, and 3;

[0057] Figure 13 Infrared spectrum of epoxy curing agent 2 containing dual dynamic bonds. Specific implementation method

[0059] To facilitate the understanding of the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0060] An epoxy curing agent containing dual dynamic bonds of the present invention has a general molecular structure formula:

[0061]

[0062] In the general molecular structure formula, R includes but is not limited to: straight-chain alkyl, branched-chain alkyl, cycloalkyl, heterocyclic group, alkenyl, cycloalkenyl, aromatic group, heteroaromatic group, alkylene or alkylene heteroalkylene;

[0063] Preferably, R is

[0064] In the general molecular structure formula, R 1 includes but is not limited to: hydrogen atom, straight-chain alkyl, branched-chain alkyl, cycloalkyl, heterocyclic group, alkenyl, aromatic group or heteroaromatic group;

[0065] Preferably, R 1 is H, ·CH3,

[0066] In the general molecular structure formula, R 2 includes but is not limited to: hydrogen atom, straight-chain alkyl, branched-chain alkyl, cycloalkyl, heterocyclic group, alkenyl, aromatic group or heteroaromatic group.

[0067] Preferably, R 2 is H, ·CH3,

[0068] In the general molecular structure formula, R 3including but not limited to: straight-chain alkyl, branched-chain alkyl, cycloalkyl, heterocyclic group, aryl group, heteroaryl group, alkylene or alkylene heteroalkylene;

[0069] Preferably, R 3 is

[0070] R, R 1 , R 2 and R 3 may be the same or different.

[0071] A preparation method of an epoxy curing agent containing dual dynamic bonds according to the present invention comprises the following steps:

[0072] Step 1: Add 0.001 - 10 mol of M 1 compound, 0.001 - 10 mol of N-ethoxycarbonyl phthalimide, 0.001 - 10 mol of NaHCO 3 , and 1 - 100 times the total mass of M 1 compound and N-ethoxycarbonyl phthalimide of tetrahydrofuran into a three-necked flask, stir evenly, react at room temperature for 0.1 - 20 h, filter and separate the liquid phase of the reaction system, extract and separate the organic phase with ethyl acetate, and wash the organic phase with 0.1 - 1000 times the mass of the organic phase of saturated NH 4 Cl aqueous solution, and obtain a pretreated raw material after rotary evaporation.

[0073] Step 2: Dissolve 0.001 - 10 mol of the pretreated raw material and 0.001 - 0.1 mol of organic acid in 1 - 100 times the mass of the pretreated raw material of solvent A to obtain a homogeneous solution;

[0074] Step 3: Dissolve 0.001 - 10 mol of M 2 compound in 1 - 20 times the mass of M 2 compound of solvent A to obtain a homogeneous solution;

[0075] Step 4: Dropwise add the homogeneous solution obtained in Step 3 into the homogeneous solution obtained in Step 4 within 0.5 - 2 h, and then react at 10 - 100 °C for 2 - 48 h to obtain a homogeneous solution;

[0076] Step 5: Prepare an aqueous solution with a mass concentration of 50% of 0.001 - 0.1 mol of NaOH, then drop it into the homogeneous solution obtained in Step 4 to quench the organic acid, filter the solution to collect the liquid phase and remove the solvent by vacuum distillation to obtain a homogeneous liquid or solid;

[0077] Step 6: Add 0.001 - 10 mol of the homogeneous liquid or solid obtained in Step 5, 0.001 - 10 mol of hydrazine hydrate, and ethanol in an amount 1 - 100 times the mass of the homogeneous liquid or solid into a three-necked flask. After heating under reflux for 24 h, remove the solvent to obtain a yellow transparent liquid.

[0078] Step 7: Dissolve 0.001 - 10 mol of the homogeneous liquid or solid obtained in Step 6 in a solvent B in an amount 1 - 100 times the mass of the homogeneous liquid or solid to obtain a homogeneous solution;

[0079] Step 8: Dissolve 0.001 - 10 mol of M 3 compound in a solvent B in an amount 1 - 20 times the mass of the M 3 compound to obtain a homogeneous solution;

[0080] Step 9: Dropwise add the homogeneous solution obtained in Step 8 into the homogeneous solution obtained in Step 7 within 1 - 10 h, and then react at 10 - 100 °C for 1 - 48 h to obtain a yellow solution;

[0081] Step 10: Remove the solvent B from the yellow solution obtained in Step 9 by vacuum distillation to obtain an epoxy curing agent containing double dynamic bonds.

[0082] In the above Step 1, the general formula of the M 1 compound is: In the formula, R includes but is not limited to straight-chain alkyl, branched-chain alkyl, cycloalkyl, heterocyclic group, alkenyl, cycloalkenyl, aromatic group, heteroaromatic group, alkylene or alkylene heteroalkylene;

[0083] In the above Step 1, the M 1 compound includes but is not limited to: 2-amino-1-butanol, 2-amino-2-methyl-1-propanol, DL-aminopropanol, ethanolamine, p-aminophenol, 4-aminocyclohexanol, 4-aminopyridin-3-ol or L-tryptophanol;

[0084] In the above Step 2, the organic acid includes but is not limited to: acetic acid, p-toluenesulfonic acid, benzoic acid, terephthalic acid or citric acid.

[0085] In the above Steps 2 and 3, the solvent A includes but is not limited to: ethyl acetate, dichloromethane, tetrahydrofuran or N,N-dimethylformamide.

[0086] In the above Step 3, the general formula of the M 2 compound is: In the formula, R 1 , R 2 include but are not limited to hydrogen atom, straight-chain alkyl, branched-chain alkyl, cycloalkyl, heterocyclic group, alkenyl, cycloalkenyl, aromatic group and heteroaromatic group;

[0087] In the above Step 3, the M2 The compounds include, but are not limited to: 2-methoxypropene, benzaldehyde, cyclohexanecarbaldehyde, cinnamaldehyde or 6-methylpyridine-2-carbaldehyde;

[0088] In step 7, the solvent B includes, but is not limited to: toluene, xylene, ethanol, methanol, ethyl acetate or dichloromethane.

[0089] In step 8, M 3 The general formula of the compound is: In the formula, R 3 includes, but is not limited to: linear alkyl, branched alkyl, cycloalkyl, heterocyclic group, aromatic group, heteroaromatic group, alkylene or alkylene heteroalkylene;

[0090] In step 8, M 3 The compounds include, but are not limited to: terephthalaldehyde, isophthalaldehyde, adipaldehyde, cyclohexane-1,4-dicarbaldehyde or [3,3'-bipyridine]-6,6'-dicarbaldehyde;

[0091] A preparation method of a degradable and recyclable epoxy resin material of the present invention comprises the following steps:

[0092] Step 1): Mix an epoxy curing agent containing double dynamic bonds and an epoxy resin in a mass ratio of 0.1-10:1 to obtain an epoxy mixture; the specific mass ratio of the active functional groups of the epoxy curing agent containing double dynamic bonds to the epoxy resin can be achieved within 0.1-10:1.

[0093] Step 2): Heat the epoxy mixture obtained in step 1 at 60-180 °C for 2-48 h for thermal curing to obtain a degradable and recyclable epoxy resin.

[0094] In step 1), the epoxy curing agent containing double dynamic bonds is the epoxy curing agent containing double dynamic bonds described in the present invention;

[0095] In step 1), the epoxy resin includes one or a mixture of several of aliphatic epoxy resin, alicyclic epoxy resin, aromatic epoxy resin, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, phenolic epoxy resin and o-cresol novolac epoxy resin. Preferably, the epoxy resin is bisphenol A type epoxy resin (E-51), epoxy resin TDE-85 or epoxy resin AG-80.

[0096] The following are specific examples.

[0097] Example 1

[0098] 1) Add 30.0 g of 2-amino-1-butanol, 73.8 g of N-ethoxycarbonylphthalimide, 28.3 g of NaHCO3 、1200 ml of tetrahydrofuran was added into a three-necked flask, stirred evenly, and reacted at room temperature for 10 h. The reaction system was filtered to separate the liquid phase, and the organic phase was separated by extraction with ethyl acetate. The organic phase was washed with 1000 ml of saturated aqueous solution of NH 4 Cl, and the pretreated raw material was obtained after rotary evaporation.

[0099] 2) 103.8 g of the pretreated raw material, 0.6 g of p-toluenesulfonic acid, and 150.0 ml of dichloromethane were added into a three-necked flask and stirred evenly to obtain a homogeneous solution.

[0100] 3) 30.0 g of 2-methoxypropene was dissolved in 50.0 ml of dichloromethane and slowly dropped into the three-necked flask, and reacted at 25 °C for 24 h to obtain a homogeneous solution.

[0101] 4) 0.3 g of 50% aqueous NaOH solution by mass was dropped into the homogeneous solution in step 3) and stirred for 2 h.

[0102] 5) The obtained solution was filtered, the liquid phase was collected, and dichloromethane was removed by vacuum distillation to obtain a yellow homogeneous liquid.

[0103] 6) 100 g of the yellow homogeneous liquid obtained in step 5), 50 g of hydrazine hydrate, and 2000 ml of ethanol were added into a three-necked flask. After heating under reflux for 24 h, the solvent was removed to obtain a yellow homogeneous liquid.

[0104] 7) 5.0 g of the yellow homogeneous liquid obtained in step 6) and 10.0 ml of dichloromethane were added into a three-necked flask and stirred evenly. 2.0 g of terephthalaldehyde was dissolved in 10.0 ml of dichloromethane and slowly dropped into the three-necked flask, and reacted at 25 °C for 1 h to obtain a yellow solution. Dichloromethane was removed by vacuum distillation to obtain a dual dynamic bond epoxy resin curing agent 1.

[0105] 8) 5.0 g of the dual dynamic bond epoxy resin curing agent 1 and 6.3 g of bisphenol A type epoxy resin (E-51) were fully mixed at room temperature, cured at 80 °C for 6 h, and then cured at 120 °C for 10 h to obtain a degradable and recyclable epoxy resin material 1.

[0106] See Figure 1 In (a) and (b), after the degradation of the degradable and recyclable epoxy resin material 1, the solution is clear and there is no solid residue.

[0107] See Figure 6 In (a) and (b), the degradable and recyclable epoxy resin material 1 achieves a good reconstruction effect.

[0108] See Figure 11, the glass transition temperature of the degradable and recyclable epoxy resin material 1 is 75 °C, which has good application value.

[0109] Example 2

[0110] 1) Add 20.0 g of 2-amino-2-methyl-1-propanol, 49.2 g of N-ethoxycarbonyl phthalimide, 18.9 g of NaHCO 3 , 1000 ml of tetrahydrofuran into a three-necked flask, stir evenly, react at room temperature for 10 h, filter the reaction system to separate the liquid phase, extract and separate the organic phase with ethyl acetate, and wash the organic phase with 700 ml of saturated aqueous solution of NH 4 Cl. After rotary evaporation, the pretreated raw material is obtained.

[0111] 2) Add 69.2 g of the pretreated raw material, 0.2 g of p-toluenesulfonic acid, and 200.0 ml of ethyl acetate into a three-necked flask and stir evenly.

[0112] 3) Dissolve 15.0 g of 2-methoxypropene in 20.0 ml of ethyl acetate, slowly drop it into the three-necked flask, and react at 25 °C for 16 h to obtain a homogeneous solution.

[0113] 4) Add 0.05 g of 50% aqueous NaOH solution to the reaction system and stir for 2 h.

[0114] 5) Filter the obtained solution, collect the liquid phase, and remove ethyl acetate by vacuum distillation to obtain a yellow homogeneous liquid.

[0115] 6) Add 50.0 g of the yellow transparent liquid obtained in step 5), 25.0 g of hydrazine hydrate, and 1000 ml of ethanol into a three-necked flask, heat under reflux for 24 h, and then remove the solvent to obtain a yellow homogeneous liquid.

[0116] 7) Add 5.0 g of the yellow homogeneous liquid obtained in step 6) and 25.0 ml of dichloromethane into a three-necked flask and stir evenly. Dissolve 1.5 g of terephthalaldehyde in 15.0 ml of dichloromethane, slowly drop it into the three-necked flask, and react at 25 °C for 1 h to obtain a yellow solution. Remove dichloromethane by vacuum distillation to obtain an epoxy resin curing agent 2 containing double dynamic bonds.

[0117] 8) Thoroughly mix 5.0 g of the epoxy resin curing agent 2 containing double dynamic bonds with 6.3 g of bisphenol A epoxy resin (E-51) at room temperature, cure at 100 °C for 6 h, and then cure at 130 °C for 10 h to obtain the degradable and recyclable epoxy resin material 2.

[0118] See Figure 2 In (a) and (b), after the degradable and recyclable epoxy resin material 1 degrades, the solution is clear and there is no solid residue.

[0119] See Figure 7 In (a) and (b), the degradable and reconstructable epoxy resin material 2 achieves a good reconstruction effect.

[0120] See Figure 11 , the glass transition temperature of the degradable and reconstructable epoxy resin material 2 is 75 °C, having good application value.

[0121] See Figure 13 In the infrared spectrum of the epoxy resin curing agent 2 containing double dynamic bonds, it can be seen that the structure of the epoxy resin curing agent 2 containing double dynamic bonds contains imine structure and acetal structure.

[0122] Example 3

[0123] 1) Add 20.0 g of DL-alaninol, 58.4 g of N-ethoxycarbonyl phthalimide, 22.4 g of NaHCO 3 , and 1000 ml of tetrahydrofuran into a three-necked flask, stir evenly, react at room temperature for 10 h, filter the reaction system to separate the liquid phase, extract and separate the organic phase with ethyl acetate, wash the organic phase with 800 ml of saturated aqueous NH 4 Cl solution, and obtain the pretreated raw material after rotary evaporation.

[0124] 2) Add 78.4 g of the pretreated raw material, 1.0 g of p-toluenesulfonic acid, and 100.0 ml of ethyl acetate into a three-necked flask, and stir evenly.

[0125] 3) Dissolve 10.0 g of 2-methoxypropene in 100.0 ml of ethyl acetate, slowly drop it into the three-necked flask, and react at 35 °C for 20 h to obtain a homogeneous solution.

[0126] 4) Drop 0.5 g of 50% aqueous NaOH solution by mass into the reaction system and stir for 2 h.

[0127] 5) Filter the obtained solution, collect the liquid phase, and remove ethyl acetate by vacuum distillation to obtain a yellow homogeneous liquid.

[0128] 6) Add 50.0 g of the yellow homogeneous liquid obtained in step 5), 30.0 g of hydrazine hydrate, and 1000 ml of ethanol into a three-necked flask, heat under reflux for 24 h, and then remove the solvent to obtain a yellow homogeneous liquid.

[0129] 7) Add 5.0 g of the yellow homogeneous liquid obtained in step 6) and 100 ml of dichloromethane into a three-necked flask, and stir evenly. Dissolve 5.0 g of terephthalaldehyde in 100 ml of dichloromethane, slowly drop it into the three-necked flask, and react at 25 °C for 1 h to obtain a yellow solution. Remove dichloromethane by vacuum distillation to obtain the epoxy resin curing agent 3 containing double dynamic bonds.

[0130] 8) 5.0 g of the dual-dynamic bond epoxy resin curing agent 3 and 7.1 g of bisphenol A epoxy resin (E-51) were thoroughly mixed at room temperature, cured at 60 °C for 6 h, then cured at 100 °C for 6 h, and further cured at 130 °C for 4 h to obtain the degradable and reconstructable epoxy resin material 3.

[0131] See Figure 11 , the glass transition temperature of the degradable and reconstructable epoxy resin material 3 is 70 °C, showing good application value.

[0132] Example 4

[0133] 1) 20.0 g of ethanolamine, 71.8 g of N-ethoxycarbonyl phthalimide, 27.5 g of NaHCO 3 , and 1000 ml of tetrahydrofuran were added to a three-necked flask, stirred evenly, and reacted at room temperature for 10 h. The reaction system was filtered to separate the liquid phase, and the organic phase was separated by extraction with ethyl acetate. The organic phase was washed with 800 ml of saturated aqueous NH 4 Cl solution, and the pretreated raw material was obtained after rotary evaporation.

[0134] 2) 91.8 g of the pretreated raw material, 0.5 g of acetic acid, and 200.0 ml of ethyl acetate were added to a three-necked flask and stirred evenly at 50 °C.

[0135] 3) 5.0 g of 2-methoxypropene was dissolved in 10.0 ml of ethyl acetate and added dropwise to the three-necked flask within 0.5 h, and reacted at 50 °C for 5 h to obtain a homogeneous solution.

[0136] 4) 0.66 g of 50% aqueous NaOH solution was added dropwise to the reaction system and stirred for 2 h.

[0137] 5) The obtained solution was filtered, the liquid phase was collected, and ethyl acetate was removed by vacuum distillation to obtain a yellow homogeneous liquid.

[0138] 6) 50.0 g of the yellow homogeneous liquid obtained in step 5), 35.0 g of hydrazine hydrate, and 1000 ml of ethanol were added to a three-necked flask. After heating under reflux for 24 h, the solvent was removed to obtain a yellow homogeneous liquid.

[0139] 7) 5.0 g of the yellow homogeneous liquid obtained in step 6) and 50.0 ml of dichloromethane were added to a three-necked flask and stirred evenly. 1.5 g of terephthalaldehyde was dissolved in 30.0 ml of dichloromethane and slowly added dropwise to the three-necked flask, and reacted at 25 °C for 1 h to obtain a yellow solution. Ethyl acetate was removed by vacuum distillation to obtain the dual-dynamic bond epoxy resin curing agent 4.

[0140] 8) 5.0 g of the dual-dynamic bond epoxy resin curing agent 4 and 5.6 g of epoxy resin TDE-85 were thoroughly mixed at room temperature, cured at 60 °C for 6 h, then cured at 100 °C for 6 h, and further cured at 130 °C for 6 h to obtain the degradable and recyclable epoxy resin material 4.

[0141] Example 5

[0142] 1) 20.0 g of p-aminophenol, 40.2 g of N-ethoxycarbonyl phthalimide, 15.4 g of NaHCO 3 , and 1000 ml of tetrahydrofuran were added to a three-necked flask, stirred evenly, reacted at room temperature for 10 h, the reaction system was filtered to separate the liquid phase, the organic phase was separated by extraction with ethyl acetate, and the organic phase was washed with 700 ml of saturated aqueous NH 4 Cl solution, and the pretreated raw material was obtained after rotary evaporation.

[0143] 2) 60.2 g of p-aminophenol, 0.2 g of p-toluenesulfonic acid, and 100.0 ml of DMF were added to a three-necked flask and stirred evenly at 50 °C.

[0144] 3) 10.0 g of 2-methoxypropene was dissolved in 20.0 ml of tetrahydrofuran, slowly dropped into the three-necked flask, and reacted at 50 °C for 5 h to obtain a homogeneous solution.

[0145] 4) 0.1 g of 50% aqueous NaOH solution was added dropwise to the reaction system and stirred for 2 h.

[0146] 5) The obtained solution was filtered, the liquid phase was collected, and DMF was removed by vacuum distillation to obtain a solid powder.

[0147] 6) 50.0 g of the solid powder obtained in step 5), 60.0 g of hydrazine hydrate, and 1000 ml of ethanol were added to a three-necked flask, heated under reflux for 24 h, and the solvent was removed to obtain a yellow solid.

[0148] 7) 5.0 g of the obtained yellow solid powder and 50.0 g of dichloromethane were added to a three-necked flask and stirred evenly. 1.25 g of isophthalaldehyde was dissolved in 12.5 ml of dichloromethane, slowly dropped into the three-necked flask, and reacted at 25 °C for 1 h to obtain a yellow solution. Dichloromethane was removed by vacuum distillation to obtain the dual-dynamic bond epoxy resin curing agent 5.

[0149] 8) 5.0 g of the dual-dynamic bond epoxy resin curing agent 5 and 4.2 g of epoxy resin AG-80 were thoroughly mixed at room temperature, cured at 100 °C for 6 h, then cured at 130 °C for 6 h, and further cured at 160 °C for 6 h to obtain the degradable and recyclable epoxy resin material 4.

[0150] Example 6

[0151] 1) Add 30.0 g of 4-aminocyclohexanol, 57.1 g of N-ethoxycarbonyl phthalimide, 21.9 g of NaHCO 3 , and 1000 ml of tetrahydrofuran into a three-necked flask, stir evenly, react at room temperature for 10 h, filter the reaction system to separate the liquid phase, extract with ethyl acetate to separate the organic phase, and wash the organic phase with 500 ml of saturated aqueous NH 4 Cl solution, and obtain the pretreated raw material after rotary evaporation.

[0152] 2) Add 87.1 g of the pretreated raw material, 0.6 g of citric acid, and 150.0 ml of dichloromethane into a three-necked flask and stir until homogeneous.

[0153] 3) Dissolve 14.6 g of cyclohexyl formaldehyde in 20.0 ml of dichloromethane, slowly drop it into the three-necked flask, and react at 25 °C for 48 h to obtain a homogeneous solution.

[0154] 4) Drop 0.75 g of 50% aqueous NaOH solution by mass into the homogeneous solution in step 3) and stir for 2 h.

[0155] 5) Filter the obtained solution, collect the liquid phase, and remove dichloromethane by vacuum distillation to obtain a yellow solid.

[0156] 6) Add 50 g of the yellow solid obtained in step 5), 50 g of hydrazine hydrate, and 2000 ml of ethanol into a three-necked flask, heat under reflux for 24 h, and then remove the solvent to obtain a yellow solid powder.

[0157] 7) Add 5.0 g of the yellow solid powder obtained in step 6) and 10.0 ml of dichloromethane into a three-necked flask and stir evenly. Dissolve 1.0 g of adipaldehyde in 10.0 ml of dichloromethane, slowly drop it into the three-necked flask, and react at 25 °C for 6 h to obtain a yellow solution. Remove dichloromethane by vacuum distillation to obtain the dual-dynamic bond epoxy resin curing agent 6.

[0158] Example 7

[0159] 1) Add 30.0 g of 4-aminopyridin-3-ol, 59.7 g of N-ethoxycarbonyl phthalimide, 22.9 g of NaHCO 3 , and 1000 ml of tetrahydrofuran into a three-necked flask, stir evenly, react at room temperature for 10 h, filter the reaction system to separate the liquid phase, extract with ethyl acetate to separate the organic phase, and wash the organic phase with 600 ml of saturated aqueous NH 4 Cl solution, and obtain the pretreated raw material after rotary evaporation.

[0160] 2) Add 89.7 g of the pretreated raw material, 0.6 g of citric acid, and 150.0 ml of dichloromethane into a three-necked flask, and stir until homogeneous.

[0161] 3) Dissolve 14.5 g of benzaldehyde in 20.0 ml of dichloromethane, slowly drip it into the three-necked flask, and react at 35 °C for 30 h to obtain a homogeneous solution.

[0162] 4) Drop 0.75 g of a 50% NaOH aqueous solution by mass into the homogeneous solution in step 3), and stir for 3 h.

[0163] 5) Filter the obtained solution, collect the liquid phase, and remove dichloromethane by vacuum distillation to obtain a yellow solid.

[0164] 6) Add 50 g of the yellow solid obtained in step 5), 70 g of hydrazine hydrate, and 2000 ml of ethanol into a three-necked flask, heat under reflux for 24 h, and then remove the solvent to obtain a yellow solid powder.

[0165] 7) Add 5.0 g of the yellow solid powder obtained in step 6) and 10.0 ml of dichloromethane into a three-necked flask, and stir evenly. Dissolve 1.2 g of cyclohexane-1,4-dicarboxaldehyde in 10.0 ml of dichloromethane, slowly drip it into the three-necked flask, and react at 15 °C for 6 h to obtain a yellow solution. Remove dichloromethane by vacuum distillation to obtain a dual dynamic bond epoxy resin curing agent 7.

[0166] Example 8

[0167] 1) Add 20.0 g of 2-amino-2-methyl-1-propanol, 49.2 g of N-ethoxycarbonyl phthalimide, 18.9 g of NaHCO 3 , and 1000 ml of tetrahydrofuran into a three-necked flask, stir evenly, react at room temperature for 10 h, filter the reaction system to separate out the liquid phase, extract and separate the organic phase with ethyl acetate, wash the organic phase with 700 ml of saturated aqueous NH 4 Cl solution, and obtain the pretreated raw material after rotary evaporation.

[0168] 2) Add 69.2 g of the pretreated raw material, 0.6 g of citric acid, and 150.0 ml of dichloromethane into a three-necked flask, and stir until homogeneous.

[0169] 3) Dissolve 15.0 g of cinnamaldehyde in 20.0 ml of dichloromethane, slowly drip it into the three-necked flask, and react at 25 °C for 30 h to obtain a homogeneous solution.

[0170] 4) Drop 0.75 g of a 50% NaOH aqueous solution by mass into the homogeneous solution in step 3), and stir for 2 h.

[0171] 5) Filter the obtained solution, collect the liquid phase, and remove dichloromethane by means of vacuum distillation to obtain a yellow homogeneous liquid.

[0172] 6) Add 50 g of the yellow homogeneous liquid obtained in step 5), 65 g of hydrazine hydrate, and 2000 ml of ethanol into a three-necked flask, heat under reflux for 24 h, and then remove the solvent to obtain a yellow liquid.

[0173] 7) Add 5.0 g of the yellow liquid obtained in step 6) and 10.0 ml of dichloromethane into a three-necked flask, and stir evenly. Dissolve 1.9 g of [3,3'-bipyridine]-6,6'-dicarboxaldehyde in 10.0 ml of dichloromethane, slowly drop it into the three-necked flask, and react at 25 °C for 20 h to obtain a yellow solution. Remove dichloromethane by means of vacuum distillation to obtain a double dynamic bond epoxy resin curing agent 8.

[0174] Example 9

[0175] 1) Add 20.0 g of L-tryptophanol, 23.1 g of N-ethoxycarbonyl phthalimide, 8.8 g of NaHCO 3 , and 700 ml of tetrahydrofuran into a three-necked flask, stir evenly, react at room temperature for 10 h, filter the reaction system to separate the liquid phase, extract and separate the organic phase with ethyl acetate, wash the organic phase with 400 ml of saturated aqueous NH 4 Cl solution, and obtain a pretreated raw material after rotary evaporation.

[0176] 2) Add 43.1 g of the pretreated raw material, 0.6 g of citric acid, and 150.0 ml of dichloromethane into a three-necked flask, and stir until homogeneous.

[0177] 3) Dissolve 6.4 g of 6-methyl-2-pyridinecarboxaldehyde in 10.0 ml of dichloromethane, slowly drop it into the three-necked flask, and react at 25 °C for 30 h to obtain a homogeneous solution.

[0178] 4) Drop 0.75 g of 50% NaOH aqueous solution by mass into the homogeneous solution in step 3), and stir for 2 h.

[0179] 5) Filter the obtained solution, collect the liquid phase, and remove dichloromethane by means of vacuum distillation to obtain a yellow solid.

[0180] 6) Add 30 g of the yellow solid obtained in step 5), 45 g of hydrazine hydrate, and 1000 ml of ethanol into a three-necked flask, heat under reflux for 24 h, and then remove the solvent to obtain a yellow solid.

[0181] 7) Add 5.0 g of the yellow solid obtained in step 6) and 10.0 ml of dichloromethane into a three-necked flask, and stir evenly. Dissolve 0.72 g of terephthalaldehyde in 10.0 ml of dichloromethane, and slowly drop it into the three-necked flask. React at 25 °C for 10 h to obtain a yellow solution. Remove dichloromethane by means of vacuum distillation to obtain a dual-dynamic bond epoxy resin curing agent 9.

[0182] Example 10

[0183] 1) Add 0.01 mol of 2-amino-1-butanol, 0.01 mol of N-ethoxycarbonyl phthalimide, 0.01 mol of NaHCO 3 , and 1-fold mass of tetrahydrofuran of the total mass of 2-amino-1-butanol and N-ethoxycarbonyl phthalimide into a three-necked flask, stir evenly, react at room temperature for 5 h, filter and separate the liquid phase of the reaction system, extract and separate the organic phase with ethyl acetate, and wash the organic phase with 5-fold mass of saturated aqueous solution of NH 4 Cl. After rotary evaporation, a pretreated raw material is obtained.

[0184] 2) Add 0.01 mol of the pretreated raw material, 0.001 mol of p-toluenesulfonic acid, and 1-fold mass of dichloromethane of the mass of the pretreated raw material into a three-necked flask, stir evenly to obtain a homogeneous solution.

[0185] 3) Dissolve 0.013 mol of 2-methoxypropene in 1-fold mass of dichloromethane of the mass of 2-methoxypropene, and slowly drop it into the three-necked flask. React at 10 °C for 48 h to obtain a homogeneous solution.

[0186] 4) Prepare an aqueous solution with a mass concentration of 50% by dissolving 0.001 mol of NaOH, and drop it into the homogeneous solution in step 3), and stir for 2 h.

[0187] 5) Filter the obtained solution, collect the liquid phase, and remove dichloromethane by means of vacuum distillation to obtain a yellow homogeneous liquid.

[0188] 6) Add 0.001 mol of the yellow homogeneous liquid obtained in step 5), 0.01 mol of hydrazine hydrate, and 1-fold mass of ethanol of the mass of the yellow homogeneous liquid into a three-necked flask. After heating under reflux for 24 h, remove the solvent to obtain a yellow homogeneous liquid.

[0189] 7) Add 0.002 mol of the yellow homogeneous liquid obtained in step 6) and 1-fold mass of dichloromethane of the mass of the yellow homogeneous liquid into a three-necked flask, and stir evenly. Dissolve 0.001 mol of terephthalaldehyde in 1-fold mass of dichloromethane of the mass of terephthalaldehyde, and slowly drop it into the three-necked flask. React at 10 °C for 48 h to obtain a yellow solution. Remove dichloromethane by means of vacuum distillation to obtain a dual-dynamic bond epoxy resin curing agent 10.

[0190] 8) 5.0 g of the dual-dynamic bond epoxy resin curing agent 10 and 6.5 g of bisphenol A epoxy resin (E-51) were thoroughly mixed at room temperature, cured at 60 °C for 48 h, and then cured at 120 °C for 10 h to obtain a degradable and reconstructable epoxy resin material 10.

[0191] Example 11

[0192] 1) 10 mol of 2-amino-1-butanol, 10 mol of N-ethoxycarbonyl phthalimide, 10 mol of NaHCO 3 , 2-amino-1-butanol and 100 times the total mass of N-ethoxycarbonyl phthalimide of tetrahydrofuran were added to a three-necked flask, stirred evenly, reacted at room temperature for 20 h, the reaction system was filtered to separate the liquid phase, the organic phase was separated by extraction with ethyl acetate, and the organic phase was washed with 1000 times the mass of NH 4 Cl saturated aqueous solution, and the pretreated raw material was obtained after rotary evaporation.

[0193] 2) 10 mol of the pretreated raw material, 0.1 mol of p-toluenesulfonic acid, and 100 times the mass of the pretreated raw material of dichloromethane were added to a three-necked flask, stirred evenly to obtain a homogeneous solution.

[0194] 3) 10 mol of 2-methoxypropene was dissolved in 20 times the mass of 2-methoxypropene of dichloromethane, slowly dropped into the three-necked flask, and reacted at 100 °C for 2 h to obtain a homogeneous solution.

[0195] 4) 0.1 mol of NaOH was prepared into an aqueous solution with a mass concentration of 50%, and dropped into the homogeneous solution in step 3), and stirred for 2 h.

[0196] 5) The obtained solution was filtered, the liquid phase was collected, and dichloromethane was removed by vacuum distillation to obtain a yellow homogeneous liquid.

[0197] 6) 10 mol of the yellow homogeneous liquid obtained in step 5), 10 mol of hydrazine hydrate, and 100 times the mass of the yellow homogeneous liquid of ethanol were added to a three-necked flask, heated under reflux for 24 h, and the solvent was removed to obtain a yellow homogeneous liquid.

[0198] 7) 10 mol of the yellow homogeneous liquid obtained in step 6) and 100 times the mass of the yellow homogeneous liquid of dichloromethane were added to a three-necked flask, stirred evenly. 5 mol of terephthalaldehyde was dissolved in 20 times the mass of terephthalaldehyde of dichloromethane, slowly dropped into the three-necked flask, and reacted at 100 °C for 1 h to obtain a yellow solution. Dichloromethane was removed by vacuum distillation to obtain a dual-dynamic bond epoxy resin curing agent 11.

[0199] 8) 5.0 g of the dual-dynamic bond epoxy resin curing agent 11 and 6.5 g of bisphenol A epoxy resin (E-51) were thoroughly mixed at room temperature, cured at 180 °C for 2 h, and then cured at 120 °C for 10 h to obtain the degradable and reconstructable epoxy resin material 11.

[0200] Example 12

[0201] 1) 5 mol of 2-amino-1-butanol, 5 mol of N-ethoxycarbonyl phthalimide, 6 mol of NaHCO 3 , and 60 times the total mass of 2-amino-1-butanol and N-ethoxycarbonyl phthalimide of tetrahydrofuran were added to a three-necked flask, stirred evenly, reacted at room temperature for 10 h, the reaction system was filtered to separate the liquid phase, the organic phase was separated by extraction with ethyl acetate, and the organic phase was washed with 500 times the mass of the organic phase of saturated aqueous NH 4 Cl solution, and the pretreated raw material was obtained after rotary evaporation.

[0202] 2) 0.1 mol of the pretreated raw material, 0.005 mol of p-toluenesulfonic acid, and 50 times the mass of the pretreated raw material of dichloromethane were added to a three-necked flask, stirred evenly to obtain a homogeneous solution.

[0203] 3) 0.1 mol of 2-methoxypropene was dissolved in 10 times the mass of 2-methoxypropene of dichloromethane, slowly dropped into the three-necked flask, and reacted at 50 °C for 20 h to obtain a homogeneous solution.

[0204] 4) 0.005 mol of NaOH was prepared into an aqueous solution with a mass concentration of 50%, and dropped into the homogeneous solution in step 3), and stirred for 2 h.

[0205] 5) The obtained solution was filtered, the liquid phase was collected, and dichloromethane was removed by vacuum distillation to obtain a yellow homogeneous liquid.

[0206] 6) 0.1 mol of the yellow homogeneous liquid obtained in step 5), 1 mol of hydrazine hydrate, and 10 times the mass of the yellow homogeneous liquid of ethanol were added to a three-necked flask, heated under reflux for 24 h, and the solvent was removed to obtain a yellow homogeneous liquid.

[0207] 7) 0.01 mol of the yellow homogeneous liquid obtained in step 6) and 60 times the mass of the yellow homogeneous liquid of dichloromethane were added to a three-necked flask, stirred evenly. 0.02 mol of terephthalaldehyde was dissolved in 10 times the mass of terephthalaldehyde of dichloromethane, slowly dropped into the three-necked flask, and reacted at 50 °C for 20 h to obtain a yellow solution. Dichloromethane was removed by vacuum distillation to obtain the dual-dynamic bond epoxy resin curing agent 12.

[0208] 8) 5.0 g of the dual-dynamic bond epoxy resin curing agent 12 was thoroughly mixed with 5 g of bisphenol A epoxy resin (E-51) at room temperature, cured at 60 °C for 48 h, and then cured at 120 °C for 10 h to obtain a degradable and reconstructable epoxy resin material 12.

[0209] Comparative Example 1

[0210] 1) 20.0 g of polyetheramine D230 and 100.0 ml of dichloromethane were added to a three-necked flask and stirred evenly.

[0211] 2) 5.8 g of terephthalaldehyde was dissolved in 100.0 ml of dichloromethane, dropped into the three-necked flask within 2 h, and reacted at 25 °C for 1 h to obtain a yellow solution.

[0212] 3) Dichloromethane was removed by vacuum distillation to obtain Comparative Example curing agent 1.

[0213] 10.0 g of Comparative Example curing agent 1 was thoroughly mixed with 13.3 g of bisphenol A epoxy resin (E-51) at room temperature, cured at 100 °C for 6 h, and then cured at 120 °C for 10 h to obtain Comparative Example epoxy resin material 1.

[0214] See Figure 3 In (a) and (b), there was some solid residue after the degradation of Comparative Example epoxy resin material 1.

[0215] See Figure 8 In (a) and (b), Comparative Example epoxy resin material 1 achieved a good reconstruction effect.

[0216] See Figure 12 , the glass transition temperature of Comparative Example epoxy resin material 1 was 65 °C, with good application value.

[0217] Comparative Example 2

[0218] 1) 20.0 g of 2-amino-2-methyl-1-propanol, 49.2 g of N-ethoxycarbonyl phthalimide, 18.9 g of NaHCO 3 , and 1000 ml of tetrahydrofuran were added to a three-necked flask, stirred evenly, reacted at room temperature for 10 h, the reaction system was filtered to separate the liquid phase, the organic phase was separated by extraction with ethyl acetate, and the organic phase was washed with 700 ml of NH 4 Cl aqueous solution, and the pretreated raw material was obtained after rotary evaporation.

[0219] 2) 69.2 g of the pretreated raw material, 0.2 g of p-toluenesulfonic acid, and 200.0 ml of ethyl acetate were added to a three-necked flask and stirred evenly.

[0220] 3) 15.0 g of 2-methoxypropylene was dissolved in 20.0 g of ethyl acetate, slowly dripped into the three-necked flask, and reacted at 25° C. for 16 h to obtain a uniform solution.

[0221] 4) 0.1 g of 50% NaOH aqueous solution was added dropwise to the reaction system and stirred for 2 h. The resulting solution was filtered, the liquid phase was collected, and ethyl acetate was removed by vacuum distillation to obtain a yellow uniform solution.

[0222] 5) 50.0 g of the yellow homogeneous liquid obtained in step 4), 25.0 g of hydrazine hydrate and 1000 ml of ethanol were added into a three-necked flask, and the mixture was heated under reflux for 24 h and then the solvent was removed to obtain a comparative curing agent 2.

[0223] 6) 10.0 g of comparative curing agent 2 was fully mixed with 33.0 g of bisphenol A epoxy resin (E-51) at room temperature, cured at 100° C. for 6 h, and then cured at 120° C. for 10 h to obtain comparative epoxy resin material 2.

[0224] See also Figure 4 In (a) and (b), the solution of comparative example epoxy resin material 2 is clear after degradation, and no solid residue remains.

[0225] See also Figure 9 In (a) and (b), comparative example epoxy resin material 2 cannot achieve the reconstruction effect.

[0226] See also Figure 12 The glass transition temperature of comparative example epoxy resin material 2 is 86°C, which has good application value.

[0227] Comparative Example 3

[0228] 1) 10.0 g of polyetheramine D230 and 30.0 g of bisphenol A epoxy resin (E-51) were fully mixed at room temperature, cured at 100° C. for 6 h, and then cured at 120° C. for 10 h to obtain comparative example epoxy resin material 3.

[0229] 2) See Figure 5 In (a) and (b), a large amount of solid remains after degradation of comparative example epoxy resin material 3, indicating no degradation effect.

[0230] See also Figure 10 In (a) and (b), comparative example epoxy resin material 3 cannot achieve the reconstruction effect.

[0231] See also Figure 12 The glass transition temperature of comparative example epoxy resin material 3 is 90°C, which has good application value.

[0232] Performance Test:

[0233] Glass transition temperature: Tested using a Mettler-Toledo differential scanning calorimeter, heating rate: 20 °C / min.

[0234] Degradation experiment: Place the sample in the degradation solution (V 乙酸 :V 水 = 1:1), place it at 80 °C for 6 h, and observe whether the sample is completely degraded.

[0235] Reconstitution performance: After breaking the sample, use a flat vulcanizer to hot press at 150 °C and 3 MPa for 2 h, and observe the reconstitution ability of the sample.

[0236] The test results are shown in the following table:

[0237]

[0238] The test results show that Examples 1, 2, and 3 of the degradable and reconstitutable epoxy resin materials all have good glass transition temperatures and can be used in actual application scenarios; Examples 1, 2, and 3 of the degradable and reconstitutable epoxy resin materials have good degradability and reconstitution performance. The epoxy material of Comparative Example 1 containing an imine structure but not an acetal structure has good reconstitution but poor degradability. The epoxy material of Comparative Example 2 not containing an imine structure but containing an acetal structure has good degradability but poor reconstitution performance. The epoxy material of Comparative Example 3 not containing an imine structure and not containing an acetal structure has neither degradability nor reconstitution performance.

[0239] The above only describes the best embodiments of the present invention, but it should not be construed as a limitation to the claims. The present invention is not limited to the above embodiments, and its specific structure allows changes. Any changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0240] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

Claims

1. An epoxy curing agent containing double dynamic bonds, characterized in that: The molecular structure formula of the epoxy curing agent is: In the molecular structure formula, R is a straight-chain alkyl group, a branched alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an aromatic group, a heteroaromatic group, an alkylene group, or an alkylene heteroalkylene group; In the molecular structure formula, R1 is a hydrogen atom, a straight-chain alkyl group, a branched-chain alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, an aromatic group or a heteroaromatic group; In the molecular structure formula, R2 is a hydrogen atom, a straight-chain alkyl group, a branched-chain alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, an aromatic group or a heteroaromatic group; In the general formula of the molecular structure, R3 is a straight-chain alkyl group, a branched alkyl group, a cycloalkyl group, a heterocyclic group, an aromatic group, a heteroaromatic group, an alkylene group or an alkylene heteroalkylene group.

2. A method for preparing an epoxy curing agent containing double dynamic bonds, characterized in that: The following steps are involved: The M1 compound containing an amino group and a hydroxyl group reacts with an amino protecting agent, and then is mixed with an organic acid solution and a solution of an M2 compound containing a carbonyl group, an ether bond or an aldehyde group, and reacts at 10-100° C. for 2-48 hours to obtain a uniform solution; Adding an alkaline solution to the homogeneous solution to quench the organic acid, followed by extraction, desolventization and deprotection of the protecting groups to obtain a homogeneous liquid or solid; Add a dialdehyde M3 compound solution to a uniform liquid solution or solid solution, react at 10-100° C. for 1-48 hours to obtain a yellow solution, and dry to obtain an epoxy curing agent containing a double dynamic bond.

3. The method for preparing an epoxy curing agent containing double dynamic bonds according to claim 2, characterized in that: The general formula of M1 compound is: Wherein R is a straight chain alkyl group, a branched chain alkyl group, a cycloalkyl group, a heterocyclic group, an alkenyl group, a cycloalkenyl group, an aromatic group, a heteroaromatic group, an alkylene group or an alkylene heteroalkylene group.

4. The method for preparing an epoxy curing agent containing double dynamic bonds according to claim 2, characterized in that: The organic acid is acetic acid, p-toluenesulfonic acid, benzoic acid, terephthalic acid or citric acid; The M1 compound is 2-amino-1-butanol, 2-amino-2-methyl-1-propanol, DL-aminopropanol, ethanolamine, p-aminophenol, 4-aminocyclohexanol, 4-aminopyridin-3-ol or L-tryptophanol.

5. The method for preparing an epoxy curing agent containing double dynamic bonds according to claim 2, characterized in that: The solvent in the solution of the M1 compound containing amino and hydroxyl groups and the organic acid is ethyl acetate, dichloromethane, tetrahydrofuran or N,N-dimethylformamide.

6. The method for preparing an epoxy curing agent containing double dynamic bonds according to claim 2, characterized in that: The general formula of M2 compound is: Wherein R1 and R2 are hydrogen atoms, straight-chain alkyl groups, branched-chain alkyl groups, cycloalkyl groups, heterocyclic groups, alkenyl groups, aromatic groups or heteroaromatic groups; The general formula of M3 compound is: In the formula, R3 is a straight chain alkyl group, a branched chain alkyl group, a cycloalkyl group, a heterocyclic group, an aromatic group, a heteroaromatic group, an alkylene group or an alkylene heteroalkylene group.

7. The method for preparing an epoxy curing agent containing double dynamic bonds according to claim 2, characterized in that: The M2 compound is 2-methoxypropylene, benzaldehyde, cyclohexylcarboxaldehyde, cinnamaldehyde or 6-methyl-2-pyridinealdehyde; The M3 compound is terephthalaldehyde, isophthalaldehyde, adipaldehyde, cyclohexane-1,4-dicarbaldehyde or [3,3'-bipyridine]-6,6'-dicarbaldehyde; The solvent in the solution of the M2 compound containing a carbonyl group, an ether bond or an aldehyde group is toluene, xylene, ethanol, methanol, ethyl acetate or dichloromethane.

8. The method for preparing an epoxy curing agent containing double dynamic bonds according to claim 2, characterized in that: The amino protecting agent is N-ethoxycarbonylphthalimide; The molar ratio of the M1 compound containing an amino group and a hydroxyl group to the amino protecting agent is 0.001-10:0.001-10; The molar ratio of the M1 compound containing amino and hydroxyl groups, the M2 compound containing carbonyl, ether bond or aldehyde group and the M3 compound of dialdehyde is 0.001-10:0.001-10:0.001-10.

9. A method for preparing a degradable and reconstructible epoxy resin material, characterized in that: The following steps are involved: A mixture of the epoxy curing agent containing double dynamic bonds as claimed in claim 1 and the epoxy resin in a mass ratio of 0.1-10:1 is heated at 60-180° C. for 2-48 hours for thermal curing to obtain a degradable and reconstructible epoxy resin material.

10. A degradable and reconfigurable epoxy resin material prepared according to the method of claim 9.

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