IPDA modified latent curing agent, preparation method and application thereof

Abstract

The invention discloses a preparation method and application of isophorone diamine (IPDA) modified dicyandiamide. The main raw materials for the synthesis of the compound are dicyandiamide and isophorone diamine. The invention successfully prepares a modified dicyandiamide based on alicyclic amines, and studies its application field as a latent curing agent in epoxy resin composite materials, which not only improves the stability of the curing agent mixed with the epoxy resin, but also reduces the curing temperature and shortens the curing time, and has the characteristics of high stability, low curing temperature and high strength.

Description

Technical Field

[0001] The invention belongs to the field of epoxy resin curing agents, and specifically relates to a synthesis method of a latent curing agent, and also relates to an epoxy resin composite material prepared by using the latent curing agent and its application. Background Art

[0002] Dicyandiamide is a widely used epoxy resin curing agent with excellent latent properties. The cured product has good mechanical and electrical properties. However, when used as an epoxy curing agent, it has three main disadvantages. The first is that it has poor compatibility with epoxy resin and is easy to form a heterogeneous system, which affects the curing performance; the second is that the curing temperature is too high, and its curing temperature is generally 150-220°C; the third is that the curing time is relatively long, and it generally takes more than 5 hours to fully cure. Therefore, it is of great significance to modify dicyandiamide to reduce its curing temperature and curing time to meet the needs of environmental protection, energy conservation and emission reduction.

[0003] China's public patent CN107141717A adopts a self-toughening epoxy resin / dicyandiamide curing system, which effectively improves the compatibility of dicyandiamide and epoxy resin and reduces the exothermicity of the curing reaction. However, the curing temperature of the system is still relatively high, reaching 130°C, when an accelerator is introduced.

[0004] China's public patent CN105885014A uses diaminodiphenylmethane to modify dicyandiamide to prepare a biguanide-based epoxy resin curing agent. This system effectively reduces the curing temperature, but its curing time is not significantly shortened, which limits the production efficiency of the product.

[0005] The Chinese master's thesis "Synthesis of 3,3'-dimethyl(p-biguanidino)dicyclohexylmethane and its application in epoxy resin" uses 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane (DMDC) to modify dicyandiamide to obtain a dicyclohexaneguanidino compound, which improves the stability of mixing with epoxy resin and the mechanical properties of the cast body. However, its ideal reaction and curing temperature with epoxy resin still reaches above 180°C, the reaction activity of the curing agent has not been improved, and its application in medium and low temperature fields is still limited.

[0006] In view of the above problems, the present invention has developed a method for preparing a latent curing agent based on alicyclic amine-modified dicyandiamide, and has successfully applied it to the field of epoxy resin curing agents, thereby reducing the curing temperature of the epoxy resin system, shortening the molding and curing time, and improving the storage stability of the epoxy resin system, providing possibilities for more epoxy composite material applications. Summary of the invention

[0007] The present invention discloses a preparation method and application of IPDA modified dicyandiamide. The main raw materials for the synthesis of the compound are dicyandiamide, isophoronediamine, and an acidic catalyst. The present invention successfully prepares a modified dicyandiamide based on alicyclic amines, and studies its application fields as a latent curing agent in epoxy resin composite materials, mainly including wind power, pressure vessels, automotive parts, etc. The present invention is mainly suitable for composite material hand lay-up, prepreg, winding, pultrusion, SMC and other molding processes, which not only improves the stability of the curing agent and epoxy resin mixture, but also reduces the curing temperature and shortens the curing time, and has the characteristics of high stability, low curing temperature and high strength.

[0008] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0009] An IPDA modified latent curing agent, the structural formula of which is

[0010]

[0011] In the present invention, the preparation method of the IPDA modified latent curing agent comprises the following steps:

[0012] Dicyandiamide and a solvent are added to a reactor, and the mixture is stirred and heated to disperse and dissolve. After the dicyandiamide is fully dissolved, an acidic catalyst is added dropwise to adjust the pH value of the system; a certain amount of IPDA is weighed and added dropwise to the reaction system, the system is mixed evenly and then heated to maintain the reaction reflux, during which acidic substances are continuously added to maintain a certain pH value until the reaction is completed; finally, the solvent in the system is removed, and the biguanide isophorone product is obtained after washing with an alkaline solution.

[0013] Preferably, the molar ratio of IPDA to dicyandiamide is 1:(1-4), preferably 1:(2-3);

[0014] Preferably, the solvent is one or more of distilled water, methanol, and ethanol, preferably distilled water; the amount used is 150%-500%, preferably 200%-300% of the total mass of IPDA and dicyandiamide;

[0015] Preferably, the dissolution temperature of dicyandiamide is 25-50°C, preferably 35-45°C; the dissolution time is 5-30min, preferably 10-15min;

[0016] Preferably, after adding IPDA to the system, the reaction temperature is 40-130°C, preferably 60-100°C; the reaction time is 0.5-10h, preferably 3-6h; the reaction pressure is normal pressure;

[0017] Preferably, the reflux process uses a spherical condenser;

[0018] Preferably, the acidic catalyst is one or more of hydrochloric acid, sulfuric acid, acetic acid, and nitric acid, preferably hydrochloric acid, and the adjusted pH value of the system is 1-5, preferably 2-3;

[0019] The method of removing the solvent in the system is one or more of rotary evaporation, distillation, and extraction, preferably rotary evaporation;

[0020] Preferably, the alkaline solution is one or more of an aqueous sodium carbonate solution, an aqueous sodium bicarbonate solution, an aqueous sodium hydroxide solution, and an aqueous potassium hydroxide solution, preferably an aqueous sodium hydroxide solution.

[0021] On the other hand, the present invention provides a method for preparing an epoxy resin composition, which is prepared by mixing the above-synthesized IPDA-modified latent curing agent with an epoxy resin, comprising the following steps: a. grinding the curing agent with a grinder; b. adding the epoxy resin and the curing agent into a reaction kettle, and heating and stirring to dissolve.

[0022] Preferably, the grinding mill is selected from one or more of a ball mill and a three-roll mill, preferably a three-roll mill;

[0023] Preferably, the curing agent is ground 1-5 times, preferably 3-4 times;

[0024] Preferably, the epoxy resin is selected from one or more of bisphenol A glycidyl ether, bisphenol F glycidyl ether, and aliphatic glycidyl ether;

[0025] The mass ratio of bisphenol A glycidyl ether, bisphenol F glycidyl ether, and aliphatic glycidyl ether is (50-85):(5-25):(5-25), preferably (70-80):(10-15):(10-15);

[0026] The mass ratio of the epoxy resin to the IPDA modified latent curing agent is 100:(3-15), preferably 100:(5-10);

[0027] Preferably, the heating temperature is 30-60°C, preferably 40-50°C, and the heating time is 30-90min, preferably 50-70min;

[0028] On the other hand, the present invention provides a method for preparing an epoxy resin composite material, which comprises the following steps: preparing the epoxy resin composite material by compounding the above epoxy resin composition with fibers and curing the composite material by heating.

[0029] Preferably, the preparation method comprises one or more of hand lay-up molding, winding molding, pultrusion molding, prepreg molding, and SMC molding;

[0030] Preferably, the fiber includes one or more of carbon fiber, glass fiber, bamboo fiber, and aramid fiber;

[0031] Preferably, the mass ratio of the epoxy resin composition to the fiber is 1:(2-6), preferably 1:(3-5);

[0032] Preferably, during the preparation of the composite material, the molding temperature is 80-130° C., preferably 90-110° C., and the molding time is 0.5-2 h, preferably 1-1.5 h.

[0033] Finally, the present invention also provides applications of the epoxy resin composite material in the fields of wind power materials, pressure vessels, automobile parts, etc.

[0034] The beneficial effects of the present invention are:

[0035] (1) By modifying dicyandiamide with IPDA, the synthetic route is simple, the raw materials are easy to obtain, it is suitable for industrial scale-up production, and has outstanding economic value.

[0036] (2) Biguanidinium isophorone has better compatibility with epoxy resin compositions than dicyandiamide, which effectively solves the problem that conventional latent curing agents are difficult to be compatible with epoxy resins.

[0037] (3) The synthesized curing agent reduces the curing temperature of the epoxy resin, which is 50-80°C lower than that of dicyandiamide and dicyclohexaneguanidine compounds, and the curing time is shortened by more than 30%, thereby improving the medium and high temperature activity of the composition while ensuring low temperature stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is the infrared spectrum of dicyandiamide, isophoronediamine, and isophoronediamine modified curing agent molecules;

[0039] Figure 2 This is a mechanism diagram of the curing reaction of biguanide isophorone and epoxy resin composition. DETAILED DESCRIPTION

[0040] The present invention is further described by means of specific embodiments. The embodiments of the present invention are only used as illustrations of the present invention and do not limit the scope of the present invention.

[0041] The raw materials and their sources are listed in Table 1.

[0042] Table 1 Raw materials and sources

[0043] Chemical name factory Bisphenol A epoxy resin (DER 331) The Dow Chemical Company Bisphenol F epoxy resin (DER 354) The Dow Chemical Company Aliphatic epoxy resin (748, 622) Anhui Xinyuan Technology Co., Ltd. Isophorone diamine (IPDA) Wanhua Chemical Group Co., Ltd. 3,3'-Dimethyl-4,4'-diamino-dicyclohexylmethane (DMDC) Shanghai Aladdin Biochemical Technology Co., Ltd. Dicyandiamide (DICY) Sigma-Aldrich Biochemical Technology Co., Ltd. Hydrochloric acid (HCl, 37% wt) Shanghai Aladdin Biochemical Technology Co., Ltd.

[0044] Other raw materials are commercially available unless otherwise specified.

[0045] Preparation Example 1

[0046] 4.2g of dicyandiamide was added to a 100mL three-necked flask, and 20mL of distilled water was added. After stirring, it was heated to 40°C, and refluxed through a spherical condenser. After the system was mixed evenly, concentrated hydrochloric acid was added dropwise until the system pH value was 1, and the reaction was continued for 30min. 8.5g of IPDA was weighed and added dropwise to the reaction system. After the system was mixed evenly, the temperature was raised to 40°C, and the reaction was kept refluxed for 6h. During this period, concentrated hydrochloric acid was continuously added to keep the pH value at about 1 until the reaction was completed, and a crude product of biguanide isophorone was obtained. The obtained crude product was slowly cooled and filtered, and 1mol / L of NaOH aqueous solution was slowly added dropwise to the filtrate until no precipitation was produced. The precipitate was obtained by filtering the mother liquor, and washed 3 times with distilled water to obtain a white and pure biguanide isophorone product with a yield of 76%.

[0047] Preparation Example 2

[0048] 8.4g of dicyandiamide was added to a 100mL three-necked flask, 40mL of distilled water was added, and the mixture was heated to 60°C after stirring. The mixture was refluxed through a spherical condenser. After the mixture was mixed evenly, concentrated hydrochloric acid was added until the pH value of the mixture was 5, and the reaction was continued for 30 minutes. 8.5g of IPDA was added dropwise to the reaction system. After the mixture was mixed evenly, the temperature was raised to 130°C, and the reaction was kept refluxed for 10 hours. During this period, concentrated hydrochloric acid was continuously added to keep the pH value at about 5 until the reaction was completed. The crude product of biguanide isophorone was obtained. The obtained crude product was slowly cooled and filtered, and 1mol / L of NaOH aqueous solution was slowly added to the filtrate until no precipitation was produced. The precipitate was obtained by filtering the mother liquor, and the product was washed 3 times with distilled water to obtain a white and pure biguanide isophorone product with a yield of 93%.

[0049] Preparation Example 3

[0050] 16.8g of dicyandiamide was added to a 250mL three-necked flask, and 125mL of distilled water was added. After stirring, it was heated to 60°C, and refluxed through a spherical condenser. After the system was mixed evenly, concentrated hydrochloric acid was added until the system pH value was 3, and the reaction was 30min. 8.5g of IPDA was weighed and added dropwise to the reaction system. After the system was mixed evenly, the temperature was raised to 80°C, and the reaction was kept refluxed for 0.5h. During this period, concentrated hydrochloric acid was continuously added to keep the pH value at about 3 until the reaction was completed, and the crude product of biguanide isophorone was obtained. The obtained crude product was slowly cooled and filtered, and 1mol / L of NaOH aqueous solution was slowly added to the filtrate until no precipitation was produced. The precipitate was obtained by filtering the mother liquor, and it was washed 3 times with distilled water to obtain a white and pure biguanide isophorone product with a yield of 87%.

[0051] Preparation Example 4

[0052] In a 100mL three-necked flask, add 8.4g of dicyandiamide and 40mL of distilled water. After stirring, heat to 40°C, reflux through a spherical condenser, mix the system evenly, add concentrated hydrochloric acid until the pH value of the system is 1, and react for 30 minutes. Weigh 12g of DMDC and add it dropwise to the reaction system. After the system is evenly mixed, the temperature is raised to 100°C, and the reaction is kept refluxed for 6h. During this period, concentrated hydrochloric acid is continuously added to keep the pH value at about 1 until the reaction is completed. At this time, a crude product of biguanide isophorone is obtained. The obtained crude product is slowly cooled and filtered, and 1mol / L NaOH aqueous solution is slowly added to the filtrate until no precipitation is produced. The precipitate is obtained by filtering the mother liquor, and washed 3 times with distilled water to obtain a white and pure 3,3-dimethyl (p-biguanide) dicyclohexylmethane product with a yield of 81%. Example 1

[0053] (1) Epoxy Resin Composition: 100 g of epoxy resin composition (85 g of bisphenol A glycidyl ether, 5 g of bisphenol F glycidyl ether, and 10 g of butanediol diglycidyl ether) and 5 g of biguanide isophorone curing agent ground by a three-roll mill were weighed, and the epoxy resin and curing agent were uniformly mixed by a disperser, and the bubbles were removed by a vacuum drying oven at a vacuum degree of 0.1 MPa and a temperature of 25°C.

[0054] (2) Heating and curing: The mixture obtained in step (1) is heated at 80° C. for 2 h to obtain a cured epoxy resin casting.

[0055] Example 2

[0056] (1) Epoxy Resin Composition: 100 g of epoxy resin composition (50 g of bisphenol A glycidyl ether, 25 g of bisphenol F glycidyl ether, and 25 g of butanediol diglycidyl ether) and 15 g of biguanide isophorone curing agent ground by a three-roll mill were weighed, and the epoxy resin and curing agent were uniformly mixed by a disperser, and the bubbles were removed by a vacuum drying oven at a vacuum degree of 0.1 MPa and a temperature of 25°C.

[0057] (2) Curing by heating: The mixture obtained in step (1) is heated at 130° C. for 0.5 h to obtain a cured epoxy resin casting.

[0058] Example 3

[0059] (1) Epoxy Resin Composition: 100 g of epoxy resin composition (75 g of bisphenol A glycidyl ether, 10 g of bisphenol F glycidyl ether, and 15 g of butanediol diglycidyl ether) and 8 g of biguanide isophorone curing agent ground by a three-roll mill were weighed, and the epoxy resin and curing agent were uniformly mixed by a disperser, and the bubbles were removed by a vacuum drying oven at a vacuum degree of 0.1 MPa and a temperature of 25°C.

[0060] (2) Curing by heating: The mixture obtained in step (1) is heated at 110° C. for 1.5 h to obtain a cured epoxy resin casting.

[0061] Comparative Example 1

[0062] (1) Epoxy resin composition: 100 g of epoxy resin composition (75 g of bisphenol A glycidyl ether, 10 g of bisphenol F glycidyl ether, and 15 g of butanediol diglycidyl ether) was weighed by mass fraction, and 5 g of dicyandiamide curing agent ground by a three-roll mill was mixed uniformly with the epoxy resin and the curing agent by a disperser, and the bubbles were removed by a vacuum drying oven with a vacuum degree of 0.1 MPa and a temperature of 25°C.

[0063] (2) Heating and curing: The mixture obtained in step (1) is heated at 80° C. for 2 h to obtain a cured epoxy resin casting.

[0064] Comparative Example 2

[0065] (1) Epoxy resin composition: 100 g of epoxy resin composition (75 g of bisphenol A glycidyl ether, 10 g of bisphenol F glycidyl ether, and 15 g of butanediol diglycidyl ether) was weighed by mass fraction, and 8 g of dicyandiamide curing agent ground by a three-roll mill was mixed uniformly with the epoxy resin and the curing agent by a disperser, and the bubbles were removed by a vacuum drying oven with a vacuum degree of 0.1 MPa and a temperature of 25°C.

[0066] (2) Curing by heating: The mixture obtained in step (1) is heated at 130° C. for 0.5 h to obtain a cured epoxy resin casting.

[0067] Comparative Example 3

[0068] (1) Epoxy resin composition: 100 g of epoxy resin composition (75 g of bisphenol A glycidyl ether, 10 g of bisphenol F glycidyl ether, and 15 g of butanediol diglycidyl ether) was weighed by mass fraction, and 8 g of dicyandiamide curing agent ground by a three-roll mill was mixed uniformly with the epoxy resin and the curing agent by a disperser, and the bubbles were removed by a vacuum drying oven with a vacuum degree of 0.1 MPa and a temperature of 25°C.

[0069] (2) Heating and curing: The mixture obtained in step (1) is heated at 150° C. for 2 h to obtain a cured epoxy resin casting.

[0070] Comparative Example 4

[0071] (1) Epoxy resin composition: 100 g of epoxy resin composition (75 g of bisphenol A glycidyl ether, 10 g of bisphenol F glycidyl ether, and 15 g of butanediol diglycidyl ether) was weighed by mass fraction, and 8 g of dicyandiamide curing agent ground by a three-roll mill was mixed uniformly with the epoxy resin and the curing agent by a disperser, and the bubbles were removed by a vacuum drying oven with a vacuum degree of 0.1 MPa and a temperature of 25°C.

[0072] (2) Heating and curing: The mixture obtained in step (1) is heated at 150° C. for 5 h to obtain a cured epoxy resin casting.

[0073] Comparative Example 5

[0074] (1) Epoxy resin composition: 100 g of epoxy resin composition (75 g of bisphenol A glycidyl ether, 10 g of bisphenol F glycidyl ether, and 15 g of butanediol diglycidyl ether) was weighed by mass fraction, and 5 g of 3,3-dimethyl (p-biguanidino) dicyclohexylmethane curing agent ground by a three-roll mill was taken. The epoxy resin and the curing agent were mixed evenly by a disperser, and the bubbles were removed by a vacuum drying oven with a vacuum degree of 0.1 MPa and a temperature of 25°C.

[0075] (2) Heating and curing: The mixture obtained in step (1) is heated at 120° C. for 2 h to obtain a cured epoxy resin casting.

[0076] Example 4

[0077] The preparation and molding of epoxy resin composite materials are as follows:

[0078] (1) The epoxy resin / curing agent composition prepared in step (1) of Example 3 was used to prepare a film by a coating machine, and then the film was spread on the glass fiber in a prepreg machine for impregnation. After impregnation, the mass ratio of the resin to the glass fiber was 1:3.

[0079] (2) The prepreg was cut into a size matching the mold, spread on the mold surface, and heated to 110° C. for curing. After 1.5 hours, a molded composite material product was obtained with a molding pressure of 0.8 MPa.

[0080] Example 5

[0081] The preparation and molding of epoxy resin composite materials are as follows:

[0082] (1) The epoxy resin / curing agent composition prepared in step (1) of Example 3 was used to prepare a film by a coating machine, and then the film was spread on the glass fiber in a prepreg machine for impregnation. After impregnation, the mass ratio of the resin to the glass fiber was 1:6.

[0083] (2) The prepreg is cut to a size matching the mold, spread on the mold surface, and heated to 130° C. for curing. After 0.5 hours, a molded composite material product is obtained, and the molding pressure is 0.8 MPa.

[0084] Example 6

[0085] The preparation and molding of epoxy resin composite materials are as follows:

[0086] (1) The epoxy resin / curing agent composition prepared in step (1) of Example 3 is used to prepare a film by a coating machine, and then the film is spread on the glass fiber in a prepreg machine for impregnation. After impregnation, the mass ratio of the resin to the glass fiber is 1:2.

[0087] (2) The prepreg is cut to a size matching the mold, spread on the mold surface, and heated to 80° C. for curing. After 2 hours, a molded composite material product is obtained, and the molding pressure is 0.8 MPa.

[0088] Table 1 Comparison of curing properties of epoxy resin castings

[0089]

[0090] The above gel time is measured by a gel tester, and the mixed viscosity is measured by a rotational viscometer; the tensile strength is measured according to ISO527-2 standard, the flexural strength is measured according to ISO178 standard, and the heat deformation temperature is measured according to ISO75-2 standard.

[0091] Table 1 provides the gel time of epoxy resin casting, compatibility with curing agent, initial mixing viscosity, mechanical properties and heat resistance. It can be seen from Examples 1-3 that dicyandiamide modified with isophorone diamine as epoxy resin curing agent has better comprehensive performance. From Comparative Examples 1 and 2, it can be seen that the strength of the cured product of dicyandiamide at low temperature is low or even no strength, the material performance is low, it is difficult to meet the composite material requirements, and there is no practical application value. The side reflects that the curing activity of dicyandiamide is low, and it is difficult to obtain high-performance materials by medium and low temperature curing. From Comparative Examples 3 and 4, it can be seen that if the dicyandiamide curing agent system is to obtain a high-performance epoxy resin casting, it requires a higher temperature and curing time than biguanide isophorone, which not only reduces production efficiency, but also greatly improves energy consumption, thereby increasing production costs. Comparative Example 5 synthesized a dicyclohexane guanidine compound. Due to the presence of a bicyclic and a side methyl group, its activity is low compared to biguanide isophorone, and its low-temperature curing performance is poor, which is not suitable for use under medium and low temperature composite material molding processes.

[0092] Table 2 Comparison of curing properties of epoxy resin composite materials

[0093]

[0094] The above tensile properties are measured by a universal testing tensile machine, and the interlaminar shear properties are measured by a short beam shear test (SBS); the tensile properties in the 0° direction are measured according to the ISO 527-5 Type A standard, the tensile properties in the 90° direction are measured according to the ISO 527-5 Type B standard, and the interlaminar shear is measured according to the ASTM 7078 standard.

Claims

1. An IPDA modified latent curing agent, whose structural formula is 2. The method for preparing an IPDA-modified latent curing agent according to claim 1, wherein: The following steps are involved: Dicyandiamide and a solvent are added to a reactor, and the mixture is stirred and heated to disperse and dissolve. After the dicyandiamide is fully dissolved, an acidic catalyst is added dropwise to adjust the pH value of the system; a certain amount of IPDA is weighed and added dropwise to the reaction system, the system is mixed evenly and then heated to maintain the reaction reflux, during which acidic substances are continuously added to maintain a certain pH value until the reaction is completed; finally, the solvent in the system is removed, and the biguanide isophorone product is obtained after washing with an alkaline solution.

3. The preparation method according to claim 2, characterized in that: The molar ratio of IPDA to dicyandiamide is 1:(1-4).

4. The preparation method according to claim 3, characterized in that: The molar ratio of IPDA to dicyandiamide is 1:(2-3).

5. The preparation method according to claim 2, characterized in that: The solvent is one or more of distilled water, methanol, and ethanol; the amount used is 150%-500% of the total mass of IPDA and dicyandiamide; and / or the acid catalyst is one or more of hydrochloric acid, sulfuric acid, acetic acid, and nitric acid, and the adjusted system pH value is 1-5; and / or the alkaline solution is one or more of sodium carbonate aqueous solution, sodium bicarbonate aqueous solution, sodium hydroxide aqueous solution, and potassium hydroxide aqueous solution.

6. The preparation method according to any one of claims 2 to 5, characterized in that: The dissolution temperature of dicyandiamide is 25-50° C., the dissolution time is 5-30 min, and / or, the reaction temperature after adding IPDA to the system is 40-130° C., the reaction time is 0.5-10 h, and the reaction pressure is normal pressure.

7. The preparation method according to claim 6, characterized in that: The dissolution temperature of dicyandiamide is 35-45° C., and the dissolution time is 10-15 min. and / or, the reaction temperature after adding IPDA to the system is 60-100° C., and the reaction time is 3-6 h.

8. A method for preparing an epoxy resin composition, which is prepared by mixing an IPDA-modified latent curing agent with an epoxy resin, comprising the following steps: a. Grind the curing agent with a grinder; b. Add epoxy resin and curing agent into a reaction kettle, and heat and stir to dissolve, wherein the IPDA-modified latent curing agent is selected from the IPDA-modified latent curing agent according to claim 1 or the IPDA-modified latent curing agent prepared by any one of the preparation methods of claims 2-7.

9. The preparation method according to claim 8, characterized in that: The epoxy resin is selected from one or more of bisphenol A glycidyl ether, bisphenol F glycidyl ether, and aliphatic glycidyl ether; and / or the mass ratio of the epoxy resin to the IPDA modified latent curing agent is 100:(3-15).

10. The preparation method according to claim 8 or 9, characterized in that: The heating temperature is 30-60° C., and the heating time is 30-90 min.

11. The preparation method according to claim 10, characterized in that: The heating temperature is 40-50° C., and the heating time is 50-70 minutes.

12. A method for preparing an epoxy resin composite material, characterized in that: The method comprises the following steps: compounding the epoxy resin composition prepared by the preparation method according to any one of claims 8 to 11 with fibers and curing the composite by heating.

13. The preparation method according to claim 12, characterized in that: The fibers include one or more of carbon fibers, glass fibers, bamboo fibers, and aramid fibers; and / or the mass ratio of the epoxy resin composition to the fibers is 1:(2-6); and / or the molding temperature during the preparation of the composite material is 80-130° C. and the molding time is 0.5-2 h.

14. The preparation method according to claim 13, characterized in that: The mass ratio of the epoxy resin composition to the fiber is 1:(3-5); and / or, the molding temperature during the preparation of the composite material is 90-110° C. and the molding time is 1-1.5 h.

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