Aromatic amine curing agent with low eutectic point, cured epoxy resin and preparation method and application of aromatic amine curing agent

Abstract

The invention discloses a low-eutectic-point aromatic amine curing agent, an epoxy resin cured product and a preparation method and application thereof, relates to the field of epoxy resin curing agents, and solves the problem that an existing aromatic amine curing agent is difficult to mix with epoxy resin at room temperature. The preparation method of the low-eutectic-point aromatic amine curing agent comprises the following steps: mixing 2-3 aromatic amines according to a mass ratio, heating to melt the aromatic amines, mechanically stirring the melt, cooling the melt to room temperature, and grinding the melt into powder to obtain the multi-element system low-eutectic-point aromatic amine curing agent. And heating the prepared low eutectic point aromatic amine curing agent to a liquid state, mixing with epoxy resin E51, and defoaming and curing to obtain the cured epoxy resin. The low eutectic point aromatic amine curing agent provided by the invention can prolong the pot life of an epoxy resin cured product, avoid the occurrence of an implosion phenomenon, maintain the characteristics of excellent heat resistance and good mechanical properties of the epoxy resin cured product, and improve the process applicability of an epoxy adhesive in a bonding assembly process.

Description

Technical Field

[0001] The invention relates to the field of epoxy resin curing agents, and in particular to a low eutectic point aromatic amine curing agent, an epoxy resin cured product, and a preparation method and application thereof. Background Art

[0002] Epoxy resin adhesive is a high-performance adhesive material formed by the reaction of epoxy resin and various curing agents (such as amines, anhydrides, phenolic resins, etc.). It has the advantages of low shrinkage, high bonding strength, dimensional stability, good processability, and multiple functions such as sealing, insulation, fastening, and corrosion protection. Epoxy resin adhesives are mainly composed of two major components: epoxy resin and curing agent. Among them, the curing agent is an important factor in determining the degree of curing and crosslinking of the adhesive. Selecting different curing agents can be formulated into epoxy resin adhesives with different performances. Aromatic amine curing agents contain a stable benzene ring structure in their molecular structure, and the amine group is directly connected to the benzene ring, which can make the cured epoxy resin show excellent heat resistance, mechanical strength and chemical stability, and are highly favored in high-performance applications. In addition, aromatic amines have weak reaction activity with epoxy resins, long gel time, no irritation and volatility. Therefore, aromatic amine curing agents have great application prospects in the aerospace materials and insulation materials industries.

[0003] At present, traditional aromatic amine curing agents usually have some significant disadvantages, such as a high melting point, which makes it difficult to mix with epoxy resin at room temperature. This high melting point characteristic requires a higher operating temperature for the curing process, which not only increases energy consumption, but may also cause thermal aging, discoloration or performance degradation of epoxy resin. For example, the commonly used aromatic amine curing agent diaminodiphenylmethane has a moderate reaction temperature with epoxy resin, excellent impact resistance and high mechanical strength of the cured product, but the melting point of diaminodiphenylmethane is relatively high (about 90°C). When using it as a curing agent, diaminodiphenylmethane and epoxy resin need to be heated to about 70-90°C in advance and then melted before mixing, which will shorten the application period of the resin system and increase the difficulty of the construction process. In addition, when aromatic amine curing agents are cured at higher temperatures, violent polymerization may occur, that is, rapid gelation and curing of the resin, which shortens the operable time and affects the applicability of the processing technology and the quality of the final product. Therefore, it is necessary to modify the aromatic amine curing agent and reduce its melting point to improve the process performance of the curing agent.

[0004] The low eutectic curing agent forms a eutectic system by selecting and compounding a variety of compounds, thereby significantly reducing the melting point and operating temperature of the curing agent. For aromatic amine curing agents, by compounding 2 to 3 aromatic amine compounds to form a low eutectic system, the melting point of the curing agent can be effectively reduced, making it compatible and evenly mixed with epoxy resin at a lower temperature, extending the applicable period of the resin, and avoiding the occurrence of violent polymerization during high-temperature curing. However, how to select a suitable aromatic amine combination and optimize its ratio to prepare a curing agent that has both low eutectic characteristics and excellent curing performance of aromatic amines is still a challenging technical problem. The existing technology has not yet completely solved the problem of using aromatic amine curing agents under low temperature conditions. Therefore, it is urgent to develop a method for preparing a low eutectic aromatic amine curing agent that can significantly improve its compatibility with epoxy resin and curing process applicability, solve the application limitations of traditional aromatic amine curing agents under low temperature conditions, and improve the process applicability and operation convenience of epoxy adhesives. Summary of the invention

[0005] In order to solve the technical problem of using the existing aromatic amine curing agent under low temperature conditions, the present invention proposes a low eutectic point aromatic amine curing agent, epoxy resin cured product and preparation method and application thereof. The technical solution of the present invention is as follows:

[0006] A low eutectic point aromatic amine curing agent, comprising 2 to 3 of the following components:

[0007] m-phenylenediamine (m-PDA), 4,4'-diaminodiphenylmethane (DDM), 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), dimethylthiotoluenediamine (DMTDA);

[0008] A mixture of m-phenylenediamine and 4,4'-diaminodiphenylmethane in a mass ratio of (30-50):(50-70);

[0009] or a mixture of 4,4'-diaminodiphenylmethane and dimethylthiotoluenediamine in a mass ratio of (20-50):(50-80);

[0010] or a mixture of m-phenylenediamine and dimethylthiotoluenediamine in a mass ratio of (30-60):(40-70);

[0011] or a mixture of m-phenylenediamine, 4,4'-diaminodiphenylmethane and 3,3'-dichloro-4,4'-diaminodiphenylmethane in a mass ratio of (40-60):(15-45):(5-35);

[0012] The melting point of the low eutectic aromatic amine curing agent is ≤50°C.

[0013] A method for preparing the low eutectic point aromatic amine curing agent comprises the following steps:

[0014] Put 2 to 3 kinds of aromatic amines into a reaction kettle in order according to the mass ratio, heat them to a molten state under nitrogen protection, mechanically stir the melt to mix it, cool it to room temperature, and then grind it into powder using a grinder to obtain a multi-system low eutectic point aromatic amine curing agent;

[0015] The temperature when heated to the molten state is 90-110°C;

[0016] The speed of mechanically stirring the melt is 200-350 rpm, and the stirring time is 2.5-4 hours.

[0017] The invention discloses an application of a low eutectic point aromatic amine curing agent, wherein the low eutectic point aromatic amine curing agent is applied in epoxy resin cured products.

[0018] An epoxy resin cured product is formed by curing the low eutectic point aromatic amine curing agent and epoxy resin E51.

[0019] A method for preparing the epoxy resin cured product comprises the following steps: heating a low eutectic point aromatic amine to a liquid state in an oven, mixing the mixture with epoxy resin E51 to obtain a glue solution, degassing the glue solution and pouring it into a mold, and curing the mold in an oven to obtain a corresponding cured product sample;

[0020] The mass ratio of the epoxy resin E51 to the low eutectic point aromatic amine is 100:(10-30);

[0021] The low eutectic point aromatic amine is heated in an oven at a temperature of 40 to 60° C. and a heating time of 20 to 60 minutes;

[0022] The curing temperature of the adhesive in the oven is 80-110° C., and the curing time is 2-5 hours.

[0023] Compared with the prior art, the present invention solves the application limitation problem of traditional aromatic amine curing agents under low temperature conditions, and has the following specific beneficial effects:

[0024] (1) Lowering the eutectic point of aromatic amine curing agent: The present invention prepares a multi-system low eutectic point aromatic amine curing agent by compounding 2-3 aromatic amines (such as m-PDA, DDM, MOCA, DMTDA). The aromatic amine curing agent can be melted at a temperature below 40°C or in a liquid state at room temperature, has low viscosity, and is easy to mix with epoxy resin and apply.

[0025] (2) Improved construction performance: Traditional aromatic amine curing agents are solid crystals at room temperature with a high melting point. They need to be heated and melted when used, which not only easily causes violent polymerization but also shortens the applicable period of the resin. The low eutectic aromatic amine curing agent of the present invention can avoid the above problems and can be mixed with epoxy resin at room temperature, thereby improving the process applicability in the adhesive assembly process.

[0026] (3) Maintaining the excellent performance of epoxy resin cured products: Although the eutectic point of epoxy resin cured products is reduced to 38.67°C, the mechanical properties of epoxy resin cured products are not affected. According to the standard GB / T1447 test, the tensile strength of the cured product mixed with low eutectic point aromatic amine and E51 epoxy resin can reach 80MPa; according to the standard GB / T 7124 test, its room temperature tensile shear strength can reach 8MPa; according to the standard GB / T 2571 test, its impact strength can reach 30KJ / m 2 These data show that epoxy resin cured products have excellent mechanical properties and high temperature resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a sample picture of the low eutectic point aromatic amine prepared in Example 2 of the present invention;

[0028] Figure 2 The DSC curve of the low eutectic point aromatic amine prepared in Example 2 of the present invention;

[0029] Figure 3 This is the TGA curve of the solidified product after the low eutectic point aromatic amine prepared in Example 2 of the present invention was mixed with E51. DETAILED DESCRIPTION

[0030] In order to make the technical solution of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the specification of the present invention. It should be noted that the following embodiments are only used to better understand the technical solution of the present invention and should not be understood as a limitation to the present invention.

[0031] Example 1.

[0032] The low eutectic point aromatic amine described in this embodiment is specifically implemented as follows:

[0033] Step 1: Preparation of low eutectic aromatic amines:

[0034] The two aromatic amines, m-PDA and DDM, were sequentially added into a reactor in a mass ratio of 40:60, heated to 110°C under nitrogen protection to melt them, and then mechanically stirred to mix them at a stirring speed of 300 rpm. After mixing for 4.0 hours, they were cooled to room temperature and then ground into powder using a grinder to obtain m-PDA / DDM binary low eutectic point aromatic amine curing agent.

[0035] Step 2: Preparation of epoxy resin cured product:

[0036] The m-PDA / DDM binary low eutectic aromatic amine curing agent was heated in an oven at 50°C for 30 minutes until it became liquid, and then mixed with the epoxy resin E51 in the ratio of E51:(m-PDA / DDM)=100:20.6. The mixture was degassed in a vacuum oven, and the glue was poured into a polytetrafluoroethylene mold and placed in an oven at 80°C for curing for 5 hours to obtain the corresponding cured product sample, which was used for tensile and impact tests.

[0037] The melting point of m-PDA / DDM binary low eutectic aromatic amine was tested by differential scanning calorimeter (DSC) and found to be 38.67°C. The tensile shear strength of the cured product obtained by curing m-PDA / DDM binary low eutectic aromatic amine with epoxy resin E51 was tested according to standard GB / T 7124, and the room temperature tensile shear strength was 8.44MPa. The tensile properties of the cured product were tested according to standard GB / T 1447, and the tensile strength was 81.54MPa, and the elongation at break was 8.48%. The impact strength of the cured product was tested according to standard GB / T 2571, and the impact strength was 27.19KJ / m 2 ; The initial decomposition temperature of the cured product tested by thermogravimetric analyzer (TGA) was 362°C.

[0038] Example 2.

[0039] The low eutectic point aromatic amine described in this embodiment is specifically implemented as follows:

[0040] Step 1: Preparation of low eutectic aromatic amines:

[0041] The two aromatic amines DDM and DMTDA were sequentially added into a reactor in a mass ratio of 30:70, heated to 90°C under nitrogen protection to melt them, and then mechanically stirred to mix them at a mechanical stirring speed of 200 rpm. After mixing for 2.5 hours, they were cooled to room temperature and then ground into powder using a grinder to obtain a DDM / DMTDA binary low eutectic point aromatic amine curing agent. Figure 1 This is a sample picture of DDM / DMTDA binary low eutectic point aromatic amine prepared in this example.

[0042] Step 2: Preparation of epoxy resin cured product:

[0043] DDM / DMTDA binary low eutectic aromatic amine curing agent and epoxy resin E51 were mixed in a ratio of E51:(DDM / DMTDA)=100:26.7, and degassing was performed in a vacuum oven. The glue was poured into a polytetrafluoroethylene mold and placed in an 80°C oven for curing for 5 hours to obtain the corresponding cured product sample, which was used for tensile and impact tests.

[0044] Figure 2 The DSC test results of DDM / DMTDA binary low eutectic aromatic amine prepared in this embodiment are as follows. Since DDM / DMTDA binary low eutectic aromatic amine is in liquid state, DSC test has no melting point. DDM / DMTDA binary low eutectic aromatic amine is cured with epoxy resin E51 to obtain a cured product. The shear strength of the cured product is tested according to standard GB / T 7124, and the room temperature shear strength is 8.27 MPa. The tensile properties of the cured product are tested according to standard GB / T 1447, and the tensile strength is 88.87 MPa, and the elongation at break is 8.17%. The impact strength of the cured product is tested according to standard GB / T 2571, and the impact strength is 38.37 KJ / m 2 ; Figure 3 The TGA test results of the DDM / DMTDA binary low eutectic point aromatic amine and epoxy resin E51 cured product prepared in this example show that the initial decomposition temperature of the cured product is 364°C.

[0045] Example 3.

[0046] The low eutectic point aromatic amine described in this embodiment is specifically implemented as follows:

[0047] Step 1: Preparation of low eutectic aromatic amines:

[0048] The two aromatic amines DDM and DMTDA were sequentially added into a reactor in a mass ratio of 50:50, heated to 90°C under nitrogen protection to melt them, and then mechanically stirred to mix them at a stirring speed of 200 rpm. After mixing for 2.5 hours, they were cooled to room temperature to obtain a DDM / DMTDA binary low eutectic point aromatic amine curing agent.

[0049] Step 2: Preparation of epoxy resin cured product:

[0050] DDM / DMTDA binary low eutectic aromatic amine curing agent and epoxy resin E51 were mixed in a ratio of E51:(DDM / DMTDA)=100:26.3, and degassing was performed in a vacuum oven. The glue was poured into a polytetrafluoroethylene mold and placed in an 80°C oven for curing for 5 hours to obtain the corresponding cured product sample, which was used for tensile and impact tests.

[0051] Since DDM / DMTDA binary low eutectic aromatic amine is liquid, it has no melting point when tested by DSC. DDM / DMTDA binary low eutectic aromatic amine is cured with epoxy resin E51 to obtain a cured product. The tensile shear strength of the cured product is tested according to standard GB / T 7124, and the room temperature tensile shear strength is 8.14MPa. The tensile properties of the cured product are tested according to standard GB / T 1447, and the tensile strength is 83.40MPa, and the elongation at break is 7.69%. The impact strength of the cured product is tested according to standard GB / T 2571, and the impact strength is 31.25KJ / m 2 ; The initial decomposition temperature of the cured product tested by TGA was 357°C.

[0052] Example 4.

[0053] The low eutectic point aromatic amine described in this embodiment is specifically implemented as follows:

[0054] Step 1: Preparation of low eutectic aromatic amines:

[0055] The two aromatic amines, m-PDA and DMTDA, were sequentially added into a reactor in a mass ratio of 40:60, heated to 100°C under nitrogen protection to melt them, and then mechanically stirred to mix them at a stirring speed of 350 rpm. After mixing for 3.0 hours, they were cooled to room temperature and ground into powder using a grinder to obtain m-PDA / DMTDA binary low eutectic point aromatic amine curing agent.

[0056] Step 2: Preparation of epoxy resin cured product:

[0057] The m-PDA / DMTDA binary low eutectic aromatic amine curing agent was heated in an oven at 40°C for 60 minutes until it became liquid, and then mixed with the epoxy resin E51 in the ratio of E51:(m-PDA / DMTDA)=100:17.7. The mixture was degassed in a vacuum oven, and the glue was poured into a polytetrafluoroethylene mold and cured in an oven at 90°C for 4 hours to obtain the corresponding cured product specimen, which was used for tensile and impact tests.

[0058] The melting point of m-PDA / DMTDA binary low eutectic aromatic amine was tested by DSC and found to be 40.25°C. After curing with epoxy resin E51, the tensile shear strength of the cured product was tested according to standard GB / T 7124, and the room temperature tensile shear strength was 7.58MPa. The tensile properties of the cured product were tested according to standard GB / T 1447, and the tensile strength was 80.08MPa, and the elongation at break was 8.63%. The impact strength of the cured product was tested according to standard GB / T2571, and the impact strength was 26.4KJ / m 2 ; The initial decomposition temperature of the cured product tested by TGA was 352°C.

[0059] Example 5.

[0060] The low eutectic point aromatic amine described in this embodiment is specifically implemented as follows:

[0061] Step 1: Preparation of low eutectic aromatic amines:

[0062] The two aromatic amines, m-PDA and DMTDA, were sequentially added into a reactor in a mass ratio of 60:40, heated to 100°C under nitrogen protection to melt them, and then mechanically stirred to mix them at a stirring speed of 350 rpm. After mixing for 3.0 hours, they were cooled to room temperature and ground into powder using a grinder to obtain m-PDA / DMTDA binary low eutectic point aromatic amine curing agent.

[0063] Step 2: Preparation of epoxy resin cured product:

[0064] The m-PDA / DMTDA binary low eutectic aromatic amine curing agent was heated in an oven at 45°C for 40 minutes until it became liquid, and then mixed with the epoxy resin E51 in the ratio of E51:(m-PDA / DMTDA)=100:18.3. The mixture was degassed in a vacuum oven, and the glue was poured into a polytetrafluoroethylene mold and cured in an oven at 110°C for 2 hours to obtain the corresponding cured product specimen, which was used for tensile and impact tests.

[0065] The melting point of m-PDA / DMTDA binary low eutectic aromatic amine was 40.28℃ tested by DSC. After curing with epoxy resin E51, the tensile shear strength of the cured product was tested according to standard GB / T 7124, and the room temperature tensile shear strength was 7.90MPa. The tensile properties of the cured product were tested according to standard GB / T 1447, and the tensile strength was 85.21MPa, and the elongation at break was 7.33%. The impact strength of the cured product was tested according to standard GB / T2571, and the impact strength was 25.35KJ / m 2 ; The initial decomposition temperature of the cured product tested by TGA was 360℃.

[0066] Example 6.

[0067] The low eutectic point aromatic amine described in this embodiment is specifically implemented as follows:

[0068] Step 1: Preparation of low eutectic aromatic amines:

[0069] The three aromatic amines, m-PDA, DDM and MOCA, were sequentially added into a reactor in a mass ratio of 40:40:20, heated to 110°C under nitrogen protection to melt them, and then mechanically stirred to mix them at a stirring speed of 300 rpm. After mixing for 3.5 hours, they were cooled to room temperature and ground into powder using a grinder to obtain a m-PDA / DDM / MOCA ternary eutectic aromatic amine curing agent.

[0070] Step 2: Preparation of epoxy resin cured product:

[0071] The m-PDA / DDM / MOCA ternary eutectic aromatic amine curing agent was heated in an oven at 60°C for 20 minutes until it became liquid, and then mixed with epoxy resin E51 in the ratio of E51:(m-PDA / DDM / MOCA)=100:17.6. The mixture was degassed in a vacuum oven, and the glue was poured into a polytetrafluoroethylene mold and cured in an oven at 100°C for 3 hours to obtain the corresponding cured product sample, which was used for tensile and impact tests.

[0072] The melting point of m-PDA / DDM / MOCA ternary low eutectic aromatic amine was 44.67℃ tested by DSC. After curing with epoxy resin E51, the tensile shear strength of the cured product was tested according to standard GB / T 7124, and the room temperature tensile shear strength was 7.65MPa. The tensile properties of the cured product were tested according to standard GB / T 1447, and the tensile strength was 72.08MPa, and the elongation at break was 7.66%. The impact strength of the cured product was tested according to standard GB / T2571, and the impact strength was 24.25KJ / m 2 ; The initial decomposition temperature of the cured product tested by TGA was 356℃.

[0073] Comparative Example 1.

[0074] The aromatic amine described in this comparative example is specifically implemented as follows:

[0075] m-PDA was selected as the curing agent. m-PDA was heated in an oven at 80°C for 60 minutes until liquid and then cooled for 10 minutes. It was mixed with epoxy resin in a ratio of epoxy resin E51:m-PDA=100:13.6. A vacuum oven was used for degassing. The glue was poured into a polytetrafluoroethylene mold. The sample was used for tensile and impact tests. Finally, the sample was placed in an oven and cured at 80°C for 2 hours and 100°C for 2 hours to obtain the corresponding cured sample.

[0076] The melting point of m-PDA tested by DSC is 64.24℃; after curing with epoxy resin E51, the tensile shear strength of the cured product was tested according to standard GB / T 7124, and its room temperature tensile shear strength was 7.57MPa; the tensile properties of the cured product were tested according to standard GB / T 1447, and its tensile strength was 32.96MPa, and the elongation at break was 3.10%; the impact strength of the cured product was tested according to standard GB / T2571, and its impact strength was 12.55KJ / m 2 ; The initial decomposition temperature of the cured product tested by TGA was 358°C.

[0077] Comparative Example 2:

[0078] DMTDA was selected as the curing agent and mixed with epoxy resin in the ratio of E51:DMTDA=100:27.3. The mixture was degassed in a vacuum oven and the glue was poured into a polytetrafluoroethylene mold. The sample was used for tensile and impact tests. Finally, the sample was placed in an oven at 80°C for 5 hours to obtain the corresponding cured sample.

[0079] Since DMTDA is in liquid state, it has no melting point. After curing with epoxy resin E51, the tensile shear strength of the cured product was tested according to standard GB / T 7124, and its room temperature tensile shear strength was 7.95MPa; the tensile properties of the cured product were tested according to standard GB / T 1447, and its tensile strength was 78.40MPa, and the elongation at break was 3.91%; the impact strength of the cured product was tested according to standard GB / T 2571, and its impact strength was 24.32KJ / m 2 The initial decomposition temperature of the solidified material tested by TGA is 350°C. The melting point and mechanical property test results of the solidified materials in the above embodiments and comparative examples are shown in the following table:

[0080]

[0081] According to the above test results, the low eutectic aromatic amine prepared by the present invention has a minimum melting point of 38.67°C, a mild reaction process, no violent polymerization, and the cured product has high temperature resistance. Among them, in Examples 1-6, the types of blended aromatic amines and the proportions added are different, and the properties of the obtained low eutectic aromatic amines are also different. Increasing the proportion of m-PDA or DDM can effectively improve the high temperature resistance of the cured product, but the melting point of the curing agent will also increase, which is not conducive to the blending of the curing agent with the epoxy resin. Increasing the liquid DMTDA component can effectively reduce the melting point of the curing agent and improve the process performance of the curing agent.

[0082] By comparing the results of Example 1 with Comparative Example 1, adding DDM to mPDA can reduce the melting point of the curing agent, and the heat resistance of the curing agent is good. By comparing the results of Example 2 with Comparative Example 2, by adding DDM to DMTDA, the low eutectic point aromatic amine prepared is liquid at room temperature, which is beneficial to improve the mechanical properties of the cured product and the bonding strength with the substrate interface, thereby having good high temperature resistance. The method of using a polyvalent aromatic amine to replace a single aromatic amine is used to prepare a curing agent with excellent comprehensive performance.

[0083] The low eutectic aromatic amine prepared by the invention can be used as a curing agent for epoxy resin, has excellent performance and good processability, and can be widely used in high-tech fields such as electrical, semiconductor electronics, special coatings and aerospace. Obviously, the above embodiments are only examples for clear explanation, and are not limitations on the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the invention.

Claims

1. A low eutectic point aromatic amine curing agent, characterized in that: Contains 2-3 of the following components: m-phenylenediamine, 4,4'-diaminodiphenylmethane, 3,3'-dichloro-4,4'-diaminodiphenylmethane, dimethylthiotoluenediamine.

2. The low eutectic point aromatic amine curing agent according to claim 1, characterized in that: The low eutectic point aromatic amine curing agent is: A mixture of m-phenylenediamine and 4,4'-diaminodiphenylmethane in a mass ratio of (30-50):(50-70); or a mixture of 4,4'-diaminodiphenylmethane and dimethylthiotoluenediamine in a mass ratio of (20-50):(50-80); or a mixture of m-phenylenediamine and dimethylthiotoluenediamine in a mass ratio of (30-60):(40-70); Or a mixture of m-phenylenediamine, 4,4'-diaminodiphenylmethane and 3,3'-dichloro-4,4'-diaminodiphenylmethane in a mass ratio of (40-60):(15-45):(5-35).

3. A method for preparing the low eutectic point aromatic amine curing agent according to claim 1 or 2, characterized in that: The steps include: 2 to 3 kinds of aromatic amines are sequentially added into a reaction kettle according to the mass ratio, heated to a molten state under nitrogen protection, the melt is mechanically stirred to mix, cooled to room temperature, and then ground into powder using a grinder to obtain a multi-system low eutectic point aromatic amine curing agent.

4. The method for preparing the low eutectic point aromatic amine curing agent according to claim 3, characterized in that: The temperature when heating to the molten state is 90-110°C.

5. The method for preparing the low eutectic point aromatic amine curing agent according to claim 3, characterized in that: The speed of the mechanical stirring is 200-350 rpm, and the mixing time is 2.5-4.0 h.

6. Use of the low eutectic point aromatic amine curing agent as claimed in claim 1 or 2, characterized in that: Low eutectic point aromatic amine curing agent is used in epoxy resin curing products.

7. An epoxy resin cured product, characterized in that: The curing agent is formed by curing the low eutectic point aromatic amine curing agent as claimed in claim 1 or 2 with epoxy resin E51.

8. A method for preparing a cured epoxy resin material as claimed in claim 7, characterized in that: The steps include: After the low eutectic point aromatic amine curing agent is heated to liquid in an oven, it is mixed with epoxy resin E51 to form a glue solution. After degassing treatment, the glue solution is poured into a mold and placed in an oven for curing to obtain a corresponding cured product sample.

9. The method for preparing a cured epoxy resin material according to claim 8, characterized in that: The mass ratio of the epoxy resin E51 to the low eutectic point aromatic amine is 100:(10-30).

10. The method for preparing a cured epoxy resin material according to claim 8, characterized in that: The low eutectic point aromatic amine curing agent is heated in an oven at a temperature of 40 to 60°C for 20 to 60 minutes; the adhesive is cured in an oven at a temperature of 80 to 110°C for 2 to 5 hours.

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