Epoxy resin curing agent and preparation method thereof
By introducing hydrophobic groups and aminocassol into the epoxy resin curing agent, a stable network structure is formed, which solves the problem of reduced curing ability of epoxy resin amine curing agents when applied underwater, especially under low temperature conditions. Excellent curing ability.
Patent Information
- Application Number
- CN202411715639.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-27
- Publication Date
- 2025-02-25
AI Technical Summary
When existing epoxy resin amine-based curing agents are used underwater, the curing agent will partially dissolve during the curing process, resulting in a combination imbalance and a reduction in curing capacity, especially under low temperature conditions.
By introducing hydrophobic groups such as nonylphenol into the epoxy resin curing agent and combining the use of amino cardisol, a more stable network structure is formed, and the compatibility and curing ability of the curing agent are improved.
Maintain excellent curing ability under low temperature conditions, improve the curing ability in water and low temperature resistance, and ensure effective curing of epoxy resin curing agent when applied underwater.
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Figure CN119505181A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of curing agents, and particularly relates to an epoxy resin curing agent and a preparation method thereof. Background Art
[0002] Epoxy resin refers to an organic polymer compound containing two or more epoxy groups in the molecule. The molecular structure of epoxy resin is characterized by the presence of active epoxy groups in the molecular chain, which can be located at the end, middle or in a ring structure of the molecular chain. Due to the presence of active epoxy groups in the molecular structure, they can undergo cross-linking reactions with various types of curing agents to form insoluble, infusible polymers with a three-dimensional network structure. As a resin matrix for adhesives, coatings and composite materials, epoxy resin is widely used in water conservancy, transportation, machinery, electronics, home appliances, automobiles and aerospace, but it belongs to the category of network polymers and has almost no value when used alone. Only when a curing agent is added during use and a curing reaction is carried out under certain conditions to generate a three-dimensional network structure product, will it show various excellent properties and become an epoxy material with real use value. It can be seen that curing agents are indispensable in the application of epoxy resins, and even play a decisive role to some extent.
[0003] With the vigorous construction of water conservancy projects in my country, a curing agent capable of underwater bonding is needed. Most epoxy resin amine curing agents are water-soluble and partially water-soluble. When used as underwater coatings or damp, wet surface coatings, the curing agent will partially dissolve in water and escape during the curing process, causing an imbalance in the ratio and failing to completely cure the epoxy resin. In order to solve this problem, hydrophobic groups such as water-insoluble nonylphenol are introduced into the design of the molecular structure of the curing agent. The hydrophobic group can hinder the interference of moisture on the curing reaction, thereby promoting the effective reaction of the curing agent with the epoxy resin and improving the curing ability of the curing agent during underwater application. However, at the same time, the introduction of hydrophobic groups may not only increase the viscosity of the curing agent, but also affect the compatibility of the curing agent with the epoxy resin, especially under low temperature conditions, which will cause a more obvious reduction in the curing ability. Summary of the invention
[0004] In order to solve the problems existing in the background technology, the present invention provides an epoxy resin curing agent and a preparation method thereof, which ensures that the prepared epoxy resin curing agent introduces hydrophobic groups while still maintaining excellent curing ability under low temperature conditions.
[0005] In order to achieve the above object, in a first aspect, the present invention provides a method for preparing an epoxy resin curing agent, comprising the following steps:
[0006] S1. Add nonylphenol and polyamine into a three-necked flask with a stirring device and a dropping funnel, stir, and heat to 50-65° C. to obtain a solution;
[0007] S2, add a formaldehyde solution with a mass concentration of 37% to the solution obtained in S1, the reaction temperature is 80-95°C, the reaction time is 2-3h, and a reaction solution 1 is obtained;
[0008] S3, adding aminocardanol to the reaction solution 1 obtained in S2, lowering the reaction temperature by 10-15°C based on the reaction temperature in S2, and the reaction time is 1-2h to obtain a reaction solution 2;
[0009] S4. Cool the reaction solution obtained in S3 to 20-30° C., add a modifier containing an active group, and react for 0.5 h to obtain an epoxy resin curing agent.
[0010] Further, the preparation method of the aminocardanol is as follows:
[0011] A1. In a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, add 180-200 mL of a 60% mass concentration of cardanol ethanol solution, 3-5 g of a cation exchange resin and 20-30 mL of acetic acid, stir, heat to 50-60°C, add 20-35 mL of hydrogen peroxide dropwise, react for 1-2 hours, stand for stratification, separate the water phase and the cation exchange resin to obtain epoxy cardanol;
[0012] A2. Add diethylenetriamine to the epoxy cardanol obtained in A1, the molar ratio of epoxy cardanol to diethylenetriamine being 1:0.3-0.4, then add 150-200 mL of an organic solvent, stir, heat to 80-90°C, react for 2-3 hours, cool to room temperature, wash away unreacted diethylenetriamine with water until the washed product does not show color to the cupric chloride solution, and thus obtain amino cardanol.
[0013] Furthermore, in A1, the cation exchange resin is Amberlite SR1LNa.
[0014] Furthermore, in A1, the stirring speed is 120-140 r / min; in A2, the stirring speed is 100-120 r / min.
[0015] Furthermore, in A2, the organic solvent includes ethanol and cyclohexane, and the mass ratio of the two is 1:1.
[0016] Furthermore, in S1, the molar ratio of nonylphenol to polyamine is 1:2-2.4.
[0017] Furthermore, in S2, the molar ratio of nonylphenol to formaldehyde is 1:1.8-2.
[0018] Furthermore, in S3, the molar ratio of nonylphenol to aminocardanol is 1:0.6-0.8.
[0019] Furthermore, in S4, the modifier containing active groups includes eugenol or thymol, and the added mass of the modifier containing active groups is 3-5% of the mass of the reaction solution 2.
[0020] In a second aspect, the present invention provides an epoxy resin curing agent prepared by the above-mentioned preparation method.
[0021] This application has the following beneficial effects:
[0022] 1. The present invention introduces hydrophobic groups by adding nonylphenol, which can prevent the interference of moisture on the curing reaction, thereby promoting the effective reaction between the curing agent and the epoxy resin and improving the curing ability of the curing agent when used underwater;
[0023] However, nonylphenol introduces non-polar long-chain alkyl groups, while the epoxy group has a certain polarity, resulting in poor compatibility. At this time, the addition of aminocardanol introduces multiple reactive polar groups, which not only improve the compatibility with the epoxy group, but also improve the overall performance of the curing agent by forming a more stable network structure, which is beneficial to improving the water curing ability and low temperature resistance of the epoxy resin curing agent. When aminocardanol is added, the reaction temperature is reduced by 10-15°C and a temperature difference is formed, which can slow down the reaction rate to a certain extent and help aminocardanol to fully react with formaldehyde, thereby forming a more uniform and complete cross-linked network.
[0024] 2. In the preparation of aminocardanol, amino groups, multiple amino groups and phenolic hydroxyl groups are introduced to make aminocardanol have higher chemical reactivity. The presence of these functional groups, especially in the Mannich reaction, can effectively react with formaldehyde and other components to form a more complex network structure. Moreover, the addition of aminocardanol also brings about a spatial effect due to its larger molecular structure, which can introduce a certain free volume into the curing network, helping to relieve the internal stress during the curing process, thereby facilitating faster curing. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 , the curing agents prepared in Examples 1-5 of the present invention and Comparative Examples 1-5 are applied to epoxy resin E-44 and the surface-drying and through-drying time are measured under different conditions to compare the trend chart. DETAILED DESCRIPTION
[0026] The present application is further described in detail below with reference to the embodiments.
[0027] Unless otherwise specified, the raw materials used in the examples and comparative examples of the present application are all commercially available.
[0028] Example 1: (1) Preparation of aminocardanol, the preparation method is as follows:
[0029] A1. In a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, add 190 mL of 60% mass concentration of cardanol ethanol solution, 4 g of cation exchange resin and 25 mL of acetic acid, stir at a stirring speed of 130 r / min, heat to 55°C, add 25 mL of hydrogen peroxide dropwise, react for 1.5 hours, stand for stratification, separate the water phase and the cation exchange resin to obtain epoxy cardanol.
[0030] A2. Add diethylenetriamine to the epoxy cardanol obtained in A1, the molar ratio of epoxy cardanol to diethylenetriamine is 1:0.35, then add 180 mL of organic solvent, stir at a stirring speed of 110 r / min, heat to 85°C, react for 2.5 hours, cool to room temperature, wash away the unreacted diethylenetriamine with water until the washed product does not show color to the cupric chloride solution, and amino cardanol is obtained.
[0031] Among them, the 60% mass concentration of cardanol ethanol solution was prepared by itself, and cardanol (industrial grade) was purchased from Shandong Hongsheng Chemical Co., Ltd. The cation exchange resin used was Amberlite SR1L Na. The organic solvent included ethanol and cyclohexane, and the mass ratio of the two was 1:1.
[0032] (2) Prepare epoxy resin curing agent, the preparation method steps are as follows:
[0033] S1. Add nonylphenol and diethylenetriamine into a three-necked flask with a stirring device and a dropping funnel, stir at a speed of 100 r / min, and heat to 60°C to obtain a solution. The molar ratio of nonylphenol to diethylenetriamine is 1:2.2.
[0034] S2. Add a formaldehyde solution with a mass concentration of 37% to the solution obtained in S1, with a reaction temperature of 85° C. and a reaction time of 2.5 h to obtain a reaction solution 1. The molar ratio of nonylphenol to formaldehyde is 1:1.9.
[0035] S3, adding aminocardanol to the reaction solution 1 obtained in S2, and lowering the reaction temperature by 12°C based on the reaction temperature in S2, i.e. reacting at 73°C for 1.5h to obtain reaction solution 2. The molar ratio of nonylphenol to aminocardanol is 1:0.7.
[0036] S4. Cool the reaction solution 2 obtained in S3 to 25° C., add thymol, the mass of thymol added is 4% of the mass of the reaction solution 2, and react for 0.5 h to obtain the epoxy resin curing agent.
[0037] Example 2: The difference between this example and Example 1 is that aminocardanol is prepared by the following method:
[0038] A1. In a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, add 180 mL of 60% mass concentration of cardanol ethanol solution, 3 g of cation exchange resin and 20 mL of acetic acid, stir at a stirring speed of 120 r / min, heat to 50°C, add 20 mL of hydrogen peroxide dropwise, react for 1 h, stand for stratification, separate the water phase and the cation exchange resin to obtain epoxy cardanol.
[0039] A2. Add diethylenetriamine to the epoxy cardanol obtained in A1, the molar ratio of epoxy cardanol to diethylenetriamine is 1:0.3, then add 150 mL of organic solvent, stir at a stirring speed of 100 r / min, heat to 80°C, react for 2 hours, cool to room temperature, wash away the unreacted diethylenetriamine with water until the washed product does not show color to the cupric chloride solution, and obtain amino cardanol.
[0040] Example 3: The difference between this example and Example 1 is that aminocardanol is prepared by the following method:
[0041] A1. In a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, add 200 mL of 60% mass concentration of cardanol ethanol solution, 5 g of cation exchange resin and 30 mL of acetic acid, stir at a stirring speed of 140 r / min, heat to 60°C, add 35 mL of hydrogen peroxide dropwise, react for 2 h, stand for stratification, separate the water phase and the cation exchange resin to obtain epoxy cardanol.
[0042] A2. Add diethylenetriamine to the epoxy cardanol obtained in A1, the molar ratio of epoxy cardanol to diethylenetriamine is 1:0.4, then add 200 mL of organic solvent, stir at a stirring speed of 120 r / min, heat to 90°C, react for 3 hours, cool to room temperature, wash away the unreacted diethylenetriamine with water until the washed product does not show color to the cupric chloride solution, and obtain amino cardanol.
[0043] Example 4: The difference between this example and Example 1 is that the epoxy resin curing agent is prepared, and the preparation method steps are as follows:
[0044] S1. Add nonylphenol and diethylenetriamine into a three-necked flask with a stirring device and a dropping funnel, stir at 100 r / min, and heat to 50°C to obtain a solution. The molar ratio of nonylphenol to diethylenetriamine is 1:2.
[0045] S2. Add a formaldehyde solution with a mass concentration of 37% to the solution obtained in S1, with a reaction temperature of 80° C. and a reaction time of 2 h to obtain a reaction solution 1. The molar ratio of nonylphenol to formaldehyde is 1:1.8.
[0046] S3, adding aminocardanol to the reaction solution 1 obtained in S2, and lowering the reaction temperature by 10°C based on the reaction temperature in S2, i.e. reacting at 70°C for 1 hour, to obtain reaction solution 2. The molar ratio of nonylphenol to aminocardanol is 1:0.6.
[0047] S4, cooling the reaction solution 2 obtained in S3 to 20° C., adding thymol, wherein the mass of thymol added is 3% of the mass of the reaction solution 2, and reacting for 0.5 h to obtain the epoxy resin curing agent.
[0048] Example 5: The difference between this example and Example 1 is that the epoxy resin curing agent is prepared, and the preparation method steps are as follows:
[0049] S1. Add nonylphenol and diethylenetriamine into a three-necked flask with a stirring device and a dropping funnel, stir at 100 r / min, and heat to 65°C to obtain a solution. The molar ratio of nonylphenol to diethylenetriamine is 1:2.4.
[0050] S2. Add a formaldehyde solution with a mass concentration of 37% to the solution obtained in S1, at a reaction temperature of 95° C. for a reaction time of 3 h to obtain a reaction solution 1. The molar ratio of nonylphenol to formaldehyde is 1:2.
[0051] S3, adding aminocardanol to the reaction solution 1 obtained in S2, and lowering the reaction temperature by 15°C based on the reaction temperature in S2, that is, reacting at 80°C for 2h to obtain reaction solution 2. The molar ratio of nonylphenol to aminocardanol is 1:0.8.
[0052] S4, cooling the reaction solution 2 obtained in S3 to 30° C., adding thymol, wherein the mass of thymol added is 5% of the mass of the reaction solution 2, and reacting for 0.5 h to obtain the epoxy resin curing agent.
[0053] Comparative Example 1: The difference between this comparative example and Example 1 is that nonylphenol is replaced by o-cresol.
[0054] Specifically, the epoxy resin curing agent is prepared, and the preparation method steps are as follows:
[0055] S1. Add o-cresol and diethylenetriamine into a three-necked flask with a stirring device and a dropping funnel, stir at a speed of 100 r / min, and heat to 60°C to obtain a solution. The molar ratio of nonylphenol to diethylenetriamine is 1:2.2.
[0056] S2. Add a formaldehyde solution with a mass concentration of 37% to the solution obtained in S1, with a reaction temperature of 85° C. and a reaction time of 2.5 h to obtain a reaction solution 1. The molar ratio of nonylphenol to formaldehyde is 1:1.9.
[0057] S3, adding aminocardanol to the reaction solution 1 obtained in S2, and lowering the reaction temperature by 12°C based on the reaction temperature in S2, i.e. reacting at 73°C for 1.5h to obtain reaction solution 2. The molar ratio of nonylphenol to aminocardanol is 1:0.7.
[0058] S4. Cool the reaction solution 2 obtained in S3 to 25° C., add thymol, the mass of thymol added is 4% of the mass of the reaction solution 2, and react for 0.5 h to obtain the epoxy resin curing agent.
[0059] Comparative Example 2: The difference between this comparative example and Example 1 is that in S3, the reaction temperature is not reduced.
[0060] Specifically, the epoxy resin curing agent is prepared, and the preparation method steps are as follows:
[0061] S1. Add nonylphenol and diethylenetriamine into a three-necked flask with a stirring device and a dropping funnel, stir at a speed of 100 r / min, and heat to 60°C to obtain a solution. The molar ratio of nonylphenol to diethylenetriamine is 1:2.2.
[0062] S2. Add a formaldehyde solution with a mass concentration of 37% to the solution obtained in S1, with a reaction temperature of 85° C. and a reaction time of 2.5 h to obtain a reaction solution 1. The molar ratio of nonylphenol to formaldehyde is 1:1.9.
[0063] S3, adding aminocardanol to the reaction solution 1 obtained in S2, maintaining the reaction temperature at 85°C for 1.5 hours to obtain reaction solution 2. The molar ratio of nonylphenol to aminocardanol is 1:0.7.
[0064] S4. Cool the reaction solution 2 obtained in S3 to 25° C., add thymol, the mass of thymol added is 4% of the mass of the reaction solution 2, and react for 0.5 h to obtain the epoxy resin curing agent.
[0065] Comparative Example 3: This comparative example differs from Example 1 in that aminocardanol is replaced by cardanol.
[0066] Specifically, the epoxy resin curing agent is prepared, and the preparation method steps are as follows:
[0067] S1. Add nonylphenol and diethylenetriamine into a three-necked flask with a stirring device and a dropping funnel, stir at a speed of 100 r / min, and heat to 60°C to obtain a solution. The molar ratio of nonylphenol to diethylenetriamine is 1:2.2.
[0068] S2. Add a formaldehyde solution with a mass concentration of 37% to the solution obtained in S1, with a reaction temperature of 85° C. and a reaction time of 2.5 h to obtain a reaction solution 1. The molar ratio of nonylphenol to formaldehyde is 1:1.9.
[0069] S3, add cardanol to the reaction solution 1 obtained in S2, and lower the reaction temperature by 12°C based on the reaction temperature in S2, that is, react at 73°C for 1.5h to obtain reaction solution 2. The molar ratio of nonylphenol to cardanol is 1:0.7.
[0070] S4. Cool the reaction solution 2 obtained in S3 to 25° C., add thymol, the mass of thymol added is 4% of the mass of the reaction solution 2, and react for 0.5 h to obtain the epoxy resin curing agent.
[0071] Comparative Example 4: This comparative example differs from Example 1 in that: in S3, the reaction temperature is not reduced, and aminocardanol is replaced by cardanol.
[0072] Specifically, the epoxy resin curing agent is prepared, and the preparation method steps are as follows:
[0073] S1. Add nonylphenol and diethylenetriamine into a three-necked flask with a stirring device and a dropping funnel, stir at a speed of 100 r / min, and heat to 60°C to obtain a solution. The molar ratio of nonylphenol to diethylenetriamine is 1:2.2.
[0074] S2. Add a formaldehyde solution with a mass concentration of 37% to the solution obtained in S1, with a reaction temperature of 85° C. and a reaction time of 2.5 h to obtain a reaction solution 1. The molar ratio of nonylphenol to formaldehyde is 1:1.9.
[0075] S3, add cardanol to the reaction solution 1 obtained in S2, keep the reaction temperature at 85°C for 1.5 hours, and obtain reaction solution 2. The molar ratio of nonylphenol to cardanol is 1:0.7.
[0076] S4. Cool the reaction solution 2 obtained in S3 to 25° C., add thymol, the mass of thymol added is 4% of the mass of the reaction solution 2, and react for 0.5 h to obtain the epoxy resin curing agent.
[0077] Comparative Example 5: The difference between this comparative example and Example 1 is that S4 is deleted, that is, thymol is deleted.
[0078] Specifically, the epoxy resin curing agent is prepared, and the preparation method steps are as follows:
[0079] S1. Add nonylphenol and diethylenetriamine into a three-necked flask with a stirring device and a dropping funnel, stir at a speed of 100 r / min, and heat to 60°C to obtain a solution. The molar ratio of nonylphenol to diethylenetriamine is 1:2.2.
[0080] S2. Add a formaldehyde solution with a mass concentration of 37% to the solution obtained in S1, with a reaction temperature of 85° C. and a reaction time of 2.5 h to obtain a reaction solution 1. The molar ratio of nonylphenol to formaldehyde is 1:1.9.
[0081] S3. Add aminocardanol to the reaction solution obtained in S2. The molar ratio of nonylphenol to aminocardanol is 1:0.7. The reaction temperature is reduced by 12°C based on the reaction temperature of S2, that is, react at 73°C for 1.5h to obtain the epoxy resin curing agent.
[0082] Test example: Test object: Epoxy resin curing agent was prepared according to Examples 1-5 and Comparative Examples 1-5.
[0083] Test method: Epoxy resin E-44 and the test object are prepared in a mass ratio of 4:1, and then the drying time (surface drying and actual drying) is tested. The curing temperature is 25°C and the low temperature is 10°C; the curing environment is underwater condition coating.
[0084] Test results: See Table 1.
[0085] Table 1. Test data of the experimental example
[0086]
[0087] Result analysis: Analyze examples 1-5 and combine the data in Table 1 and Figure 1 It can be seen that the epoxy resin curing agent prepared by the present invention ensures the introduction of hydrophobic groups, improves the curing ability in water, and still maintains excellent curing ability under low temperature conditions.
[0088] Analyze Example 1 and Comparative Example 1 and combine the data in Table 1 and Figure 1 It can be seen that the addition of nonylphenol introduces hydrophobic groups, which can significantly improve the curing ability in water.
[0089] Analyze Example 1 and Comparative Examples 2-4 and combine the data in Table 1 and Figure 1 It can be seen that the use of aminocardanol and the temperature difference change brought about by a small reduction in the reaction temperature are both beneficial to improving the water curing ability and low temperature resistance of the epoxy resin curing agent, and there is a synergistic effect between the two.
[0090] Analyze Example 1 and Comparative Example 5 and combine the data in Table 1 and Figure 1 It can be seen that the addition of thymol as a modifier containing an active group (hydroxyl) is beneficial to improving the water curing ability and low temperature resistance of the prepared epoxy resin curing agent.
[0091] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.
[0092] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.
Claims
1. A method for preparing an epoxy resin curing agent, characterized in that: The steps include: S1. Add nonylphenol and polyamine into a three-necked flask with a stirring device and a dropping funnel, stir, and heat to 50-65° C. to obtain a solution; S2, add a formaldehyde solution with a mass concentration of 37% to the solution obtained in S1, the reaction temperature is 80-95°C, the reaction time is 2-3h, and a reaction solution 1 is obtained; S3, adding aminocardanol to the reaction solution 1 obtained in S2, lowering the reaction temperature by 10-15°C based on the reaction temperature in S2, and the reaction time is 1-2h to obtain a reaction solution 2; S4. Cool the reaction solution obtained in S3 to 20-30° C., add a modifier containing an active group, and react for 0.5 h to obtain an epoxy resin curing agent.
2. The method for preparing an epoxy resin curing agent according to claim 1, characterized in that: The preparation method of the aminocardanol is as follows: A1. In a three-necked flask equipped with a stirrer, a thermometer and a reflux condenser, add 180-200 mL of a 60% mass concentration of cardanol ethanol solution, 3-5 g of a cation exchange resin and 20-30 mL of acetic acid, stir, heat to 50-60°C, add 20-35 mL of hydrogen peroxide dropwise, react for 1-2 hours, stand for stratification, separate the water phase and the cation exchange resin to obtain epoxy cardanol; A2. Add diethylenetriamine to the epoxy cardanol obtained in A1, the molar ratio of epoxy cardanol to diethylenetriamine being 1:0.3-0.4, then add 150-200 mL of an organic solvent, stir, heat to 80-90°C, react for 2-3 hours, cool to room temperature, wash away unreacted diethylenetriamine with water until the washed product does not show color to the cupric chloride solution, and thus obtain amino cardanol.
3. The method for preparing the epoxy resin curing agent according to claim 2, characterized in that: In A1, the cation exchange resin is Amberlite SR1L Na.
4. The method for preparing the epoxy resin curing agent according to claim 2, characterized in that: In A1, the stirring speed is 120-140 r / min; in A2, the stirring speed is 100-120 r / min.
5. The method for preparing the epoxy resin curing agent according to claim 2, characterized in that: In A2, the organic solvent includes ethanol and cyclohexane, and the mass ratio of the two is 1:
1.
6. The method for preparing the epoxy resin curing agent according to claim 1, characterized in that: In S1, the molar ratio of nonylphenol to polyamine is 1:2-2.
4.
7. The method for preparing the epoxy resin curing agent according to claim 1, characterized in that: In S2, the molar ratio of nonylphenol to formaldehyde is 1:1.8-2.
8. The method for preparing the epoxy resin curing agent according to claim 1, characterized in that: In S3, the molar ratio of nonylphenol to aminocardanol is 1:0.6-0.
8.
9. The method for preparing the epoxy resin curing agent according to claim 1, characterized in that: In S4, the modifier containing active groups includes eugenol or thymol, and the added mass of the modifier containing active groups is 3-5% of the mass of the second reaction solution.
10. An epoxy resin curing agent, characterized in that The method is prepared according to any one of claims 1 to 9.