Amine curing agent containing benzoxazine, epoxy resin composition and application thereof

Abstract

The invention discloses an amine curing agent containing benzoxazine, and the amine curing agent comprises a repeated daidzein group benzoxazine structural unit, and can be prepared through a Mannich reaction. The invention also discloses an epoxy resin composition which comprises an epoxy resin precursor, the benzoxazine-containing amine curing agent and a curing accelerator, an epoxy resin cured product is obtained after the epoxy resin composition is subjected to gradient curing, and compared with the epoxy resin cured product prepared from a common curing agent (4, 4-diaminodiphenyl methane), the epoxy resin cured product has the advantages that the curing effect is better; the epoxy resin cured product prepared by the invention has a relatively high limit oxygen index which reaches the V-0 grade, and has excellent flame retardant property; meanwhile, in a combustion experiment, the epoxy resin cured product prepared by the preparation method disclosed by the invention has the characteristics of small total smoke release amount, small maximum smoke density, low CO generation amount and low smoke toxicity, and is suitable for the application field with high heat resistance, high strength, flame retardance and low smoke toxicity requirements on materials.

Description

Technical Field

[0001] The present invention relates to the technical field of benzoxazine materials, and in particular to an amine curing agent containing benzoxazine, an epoxy resin composition and applications thereof. Background Art

[0002] Epoxy resin is one of the most widely used thermosetting resins. Due to its high adhesion, excellent chemical resistance, excellent mechanical properties and easy processing performance, it is widely used as an adhesive, coating and fiber composite matrix in transportation, construction facilities and aerospace. However, traditional epoxy resins have poor flame retardancy and excessive smoke toxicity. At the same time, when used as coatings and paints, they often cause large-scale bacterial growth and viral contamination due to the attachment of bacterial contaminants.

[0003] Benzoxazine resin is a new type of thermosetting resin. The Chinese patent document with publication number CN119060332A discloses a halogen-free and phosphorus-free flame-retardant modified benzoxazine resin and its preparation method, which is obtained by blending and heating with one or more benzoxazine monomers and one or more aldehyde compounds as raw materials; the benzoxazine monomers are diphenol-type benzoxazine monomers, diamine-type benzoxazine monomers, triphenol-type benzoxazine monomers or triamine-type benzoxazine monomers. Due to the almost zero curing yield, no small molecule by-products released during curing, chemical resistance, thermal stability and excellent flame retardancy and low smoke toxicity, it is widely used in aerospace, electronic packaging, rail transportation and other fields.

[0004] Daidzein is a renewable compound present in soybeans and other leguminous plants, which is green and environmentally friendly. The benzoxazine resin based on this renewable resource is environmentally friendly. Daidzein has a benzopyrone structure, has good carbonization, can improve the thermomechanical properties of thermosetting resins, and has multiple biological activities, such as antibacterial and antioxidant properties, and is widely used in the pharmaceutical industry. The Chinese patent document with publication number CN110894274A discloses a bio-based main chain benzoxazine resin based on daidzein and a preparation method thereof, and the preparation method comprises: after daidzein, furfurylamine, diamine compounds and polyformaldehyde are uniformly mixed, Mannich polymerization reaction is carried out under heating conditions to obtain.

[0005] In recent years, due to its excellent performance, it has been widely used in flame retardancy and other aspects. Inspired by this, domestic and foreign scholars introduced benzoxazine resin into the epoxy resin cross-linking network to prepare a series of new materials with excellent flame retardancy and low smoke toxicity. However, epoxy resin is prone to brittle failure under high stress conditions, which limits its service life in certain applications. Therefore, how to maintain the high strength of epoxy resin while further improving the flame retardancy of epoxy resin cured products is also a key difficulty in the current technological development. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides an amine curing agent containing benzoxazine, which contains a soybean aglycone-based benzoxazine structural unit and can be used in an epoxy resin composition, so that the cured epoxy resin has excellent flame retardant and low smoke toxicity properties.

[0007] A benzoxazine-containing amine curing agent comprises the following structural units:

[0008]

[0009] Among them, R is selected from For the connection location.

[0010] In the present invention, the amine curing agent contains repeated daidzein-based benzoxazine structural units. Daidzein is a renewable compound existing in soybeans and other leguminous plants and is green and environmentally friendly. At the same time, daidzein has a benzopyrone structure and has good charring properties, which can improve the flame retardant properties of the prepared thermosetting resin. During the curing process, the benzoxazine ring in the curing agent undergoes a ring-opening polymerization reaction to form a highly cross-linked network structure. This cross-linked structure gives the thermosetting resin excellent thermal stability and mechanical properties.

[0011] The present invention also provides a method for preparing the above amine curing agent. The method for preparing the amine curing agent is simple, easy to understand, and has controllable reaction conditions, is easy to implement, and is suitable for large-scale production.

[0012] A method for preparing an amine curing agent containing benzoxazine comprises the following steps:

[0013] Polyethylene polyamine, organic solvent, soybean aglycone and paraformaldehyde are mixed and then subjected to Mannich reaction to prepare an amine curing agent containing benzoxazine.

[0014] In the present invention, the above-mentioned daidzein is 7,4'-dihydroxyisoflavone, and its structure is shown below:

[0015]

[0016] The amino group of polyethylene polyamine attacks the carbonyl group of polyformaldehyde, causing a nucleophilic addition reaction to obtain an iminium ion intermediate. The iminium ion acts as an electrophilic reagent to attack the phenolic hydroxyl group of daidzein to obtain an amine curing agent.

[0017] Preferably, the polyethylene polyamine is one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine.

[0018] Preferably, the organic solvent is at least one of dichloromethane, chloroform, N,N-dimethylformamide, dioxane and anhydrous ethanol.

[0019] Preferably, the molar ratio of the polyethylene polyamine, daidzein and paraformaldehyde is 1:1-1.3:4-4.8.

[0020] Preferably, the Mannich reaction temperature is 90-150° C., and the reaction time is 8-24 h.

[0021] The present invention also provides an epoxy resin composition, comprising an epoxy resin precursor, the above-mentioned benzoxazine-containing amine curing agent and a curing accelerator.

[0022] The epoxy resin composition of the present invention comprises an epoxy resin precursor, the above-mentioned benzoxazine-containing amine curing agent and a curing accelerator, and can obtain an epoxy resin cured product with excellent flame retardancy and low smoke toxicity after gradient curing. Since the amine curing agent contains a benzoxazine structure, the benzoxazine itself can be cured by heating. During the curing process, the benzoxazine ring undergoes a ring-opening polymerization reaction to form a highly cross-linked network structure, which can further improve the cross-linking density and thermodynamic properties of the cured epoxy resin cured product.

[0023] Preferably, the epoxy resin precursor is selected from any of the following structures:

[0024]

[0025] Wherein, X, Y and Z are each independently selected from any of the following structures:

[0026]

[0027] R1, R2, R3 and R4 are each independently selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy, phenyl, phenoxy or C3-C7 cycloalkyl, For the connection location.

[0028] In the present invention, the epoxy resin precursor used can be bisphenol A diglycidyl ether, terephthalic acid diglycidyl ester, p-phenylenediamine tetraglycidyl amine, bisphenol A glycidyl ether, bisphenol S glycidyl ether, bisphenol S diglycidyl ether, bisphenol A epoxy resin, naphthylene diamine tetraglycidyl amine, bisphenol F glycidyl ether, etc.

[0029] Preferably, the ratio of the epoxy equivalent value in the epoxy resin precursor to the active hydrogen equivalent value of the benzoxazine-containing amine curing agent is 10:1-10.

[0030] Preferably, the curing accelerator is at least one of tertiary amine, tertiary amine salt, quaternary ammonium salt, imidazole compound, organic phosphorus compound, acetylacetonate metal salt, carboxylic acid metal salt and boron trifluoride amine complex.

[0031] In the present invention, the curing accelerator can be triethanolamine, dodecanediamine, zinc acetylacetonate, triphenylphosphine, tetrabutylammonium iodide, 2-methylimidazole, dimethylphenylamine, 2-methylimidazole, ethyl boron trifluoride, hexadecyldimethylbenzylammonium, manganese cyclohexaneate, etc.

[0032] Preferably, the mass of the curing accelerator is 0.05% to 0.5% of the total mass of the epoxy resin precursor and the benzoxazine-containing amine curing agent.

[0033] The present invention also provides a method for preparing the epoxy resin composition, comprising the following steps: uniformly mixing an epoxy resin precursor and an amine curing agent containing benzoxazine, heating, and adding a curing accelerator to obtain a composition.

[0034] The present invention also provides an epoxy resin cured product, which is obtained by gradient curing the epoxy resin composition.

[0035] The epoxy resin composition of the present invention is subjected to gradient curing to obtain an epoxy resin cured product. After testing, the epoxy resin cured product is compared with the epoxy resin cured product prepared by a commonly used curing agent (4,4-diaminodiphenylmethane). The epoxy resin cured product prepared by the present invention has higher strength and thermal stability, and the epoxy resin cured product prepared by the present invention has a higher limiting oxygen index and reaches the V-0 grade, and has excellent flame retardant properties; at the same time, the epoxy resin cured product prepared by the present invention has a small total smoke release, a small maximum smoke density, and a low CO generation in a combustion experiment, and has the characteristics of low smoke toxicity.

[0036] Preferably, the starting temperature of the gradient curing is 120°C and the end temperature is 200°C.

[0037] Further preferably, the gradient curing is curing at 120°C for 2 hours, then curing at 140°C for 2 hours, then curing at 160°C for 2 hours, then curing at 180°C for 2 hours, and finally curing at 200°C for 2 hours.

[0038] Preferably, the limiting oxygen index of the epoxy resin cured product is 30% to 35%, and the flame retardancy reaches V-0 level.

[0039] The limiting oxygen index is used to evaluate the combustion performance of epoxy resin cured products, so as to judge the ease with which epoxy resin cured products burn when they come into contact with flames in the air. The larger the limiting oxygen index, the better the flame retardant performance of the epoxy resin cured products. In the present invention, the epoxy resin cured product prepared by mixing and curing the above-mentioned benzoxazine-containing amine curing agent with an epoxy resin precursor has a high limiting oxygen index and reaches the V-0 grade, and has excellent flame retardant performance.

[0040] Preferably, the maximum smoke density of the epoxy resin cured product is 50-70 MJ / m 3 , CO generation is 0.06~0.08g / g.

[0041] The epoxy resin cured product prepared in the present invention has low total smoke release, low maximum smoke density and low CO generation in a combustion experiment, and has the characteristics of low smoke toxicity.

[0042] Preferably, the glass transition temperature of the epoxy resin cured material is 170-280°C.

[0043] In the present invention, compared with the epoxy resin cured material prepared by the commonly used curing agent (4,4-diaminodiphenylmethane), the epoxy resin cured material prepared by the present invention has a glass transition temperature within the above range, indicating that the epoxy resin cured material has a higher crosslinking density and excellent thermodynamic properties.

[0044] The present invention also provides the application of the epoxy resin cured product in the field of composite materials and electronic packaging materials. The epoxy resin cured product prepared by the present invention has the characteristics of flame retardancy and low smoke toxicity, and is suitable for application fields requiring materials with high heat resistance, high strength, flame retardancy and low smoke toxicity.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) The present invention obtains a series of amine curing agents containing benzopyrone, benzoxazine and imino structures through Mannich reaction. The preparation method is simple, the reaction conditions are controllable and easy to implement, and it is suitable for large-scale industrial production.

[0047] (2) The epoxy resin composition of the present invention comprises an epoxy resin precursor, the above-mentioned benzoxazine-containing amine curing agent and a curing accelerator, and after gradient curing, a flame retardant epoxy resin cured product with excellent low smoke toxicity can be obtained. Since the amine curing agent contains a benzoxazine structure, the benzoxazine itself can be cured by heating. During the curing process, the benzoxazine ring undergoes a ring-opening polymerization reaction to form a highly cross-linked network structure, which can further improve the cross-linking density and thermodynamic properties of the epoxy resin cured product. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 This is the hydrogen spectrum of the benzoxazine-containing amine curing agent prepared in Example 1 of the present invention.

[0049] Figure 2 This is an infrared image of the benzoxazine-containing amine curing agent prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0050] The present invention will be further described in detail below in conjunction with the examples, but the embodiments of the present invention are not limited to the following examples.

[0051] The raw materials used in the present invention are all commercially available.

[0052] The performance test experiments of the embodiments and comparative examples of the present invention are as follows:

[0053] (1) Glass transition temperature: measured on a TA Q800 dynamic mechanical properties tester in the tensile mode, with a heating rate of 3 °C / min, a temperature scanning range of 50 °C to 350 °C, and a test frequency of 1 Hz;

[0054] (2) Tensile strength: measured by a Zwick / Roell Z030 universal material testing machine, with the test temperature at 25°C and the tensile rate set at 2 mm / min. The final performance data is the average of five tests;

[0055] (3) Limiting oxygen index: This is measured on a 5801 digital oxygen index analyzer according to ASTM D2863-97. The sample is placed in a glass chimney, and a nitrogen and oxygen mixture is created through the airflow at the bottom of the chimney. The upper part of the sample is ignited, and the oxygen concentration in the flow decreases until the flame no longer burns.

[0056] (4) UL-94 vertical burning test: The test was conducted on a CZF-3 instrument according to the requirements of ASTM D3801. Two 10-s ignition tests were performed and the time it took for the sample to extinguish was recorded each time.

[0057] (5) Cone calorimetry test: Cone calorimeter test (CCT) is used to analyze the heat release of the material with a heat flux of 35kW / m 2 The samples were evaluated according to ISO 5660-1 standard, and each group of samples was measured 3 times. The gas toxicity (including CO, CO2, etc.) was analyzed according to ENISO5659-2.

[0058] (6) Smoke density test: According to ISO 5659-2 standard, use FTT0064 smoke density chamber.

[0059] Example 1

[0060] (1) Soybean aglycone (0.01 mol, 2.542 g), diethylenetriamine (0.01 mol, 1.032 g) and paraformaldehyde (0.04 mol, 1.201 g) were placed in a single-mouth bottle with a magnetic stirrer, mixed and dissolved in 50 mL of chloroform at 50° C., and heated under reflux at 100° C. for 14 hours. After the reaction was completed, the mixture was allowed to cool at room temperature, and then poured into a beaker containing 200 mL of deionized water to obtain a light yellow precipitate. After filtering, the precipitate was washed with deionized water for 2 to 3 times and dried at 60° C. to obtain a benzoxazine-containing amine curing agent 1. The H NMR spectrum of the benzoxazine-containing amine curing agent 1 is as follows: Figure 1 As shown, its structural formula is as follows:

[0061]

[0062] Among them, the average n is 14.81.

[0063] The infrared spectrum of amine curing agent 1 containing benzoxazine is shown in Figure 2 As shown, at 1627cm -1 The C=CC=O stretching vibration absorption peak in daidzein is at 1497 cm -1 The stretching vibration absorption peak of the trisubstituted benzene ring is at 1234 cm -1 and 1043cm -1 The absorption peaks of symmetric and asymmetric stretching vibration of COC on the oxazine ring are at 935 cm -1 The peak at is the characteristic peak of the oxazine ring structure. Figure 1 , 2 shows that the amine curing agent 1 was successfully prepared.

[0064] (2) The obtained benzoxazine-containing amine curing agent 1 and bisphenol A diglycidyl ether are uniformly mixed in a ratio of active hydrogen to epoxy group of 1:1, and then heated to 80°C in a blast oven for mixing, and 0.05% of triethanolamine by weight of the total mass of the mixture is added for pre-curing, and finally cured at 120°C for 2h, then at 140°C for 2h, then at 160°C for 2h, then at 180°C for 2h, and finally at 200°C for 2h to obtain an epoxy resin cured product.

[0065] Performance Testing:

[0066] The glass transition temperature (Tg) is 272°C, the tensile strength is 72MPa, the limiting oxygen index (LOI) is 30.2%, the UL-94 vertical burning test reaches V-0 level, and the peak heat release rate (PHRR) is 89MJ / m 2 , total heat release (THR) is 46KW / m 2 , the total smoke release (TSP) is 2.15m 2, CO generation is 0.076g / g, CO2 generation is 1.42g / g, and the maximum smoke density (Ds max ) is 62MJ / m 3 .

[0067] Example 2

[0068] (1) Soybean aglycone (0.01 mol, 2.542 g), triethylenetetramine (0.01 mol, 1.462 g) and paraformaldehyde (0.04 mol, 1.201 g) were placed in a single-mouth bottle with a magnetic stirrer, mixed and dissolved in 50 mL of DMF at 60° C., and heated under reflux at 120° C. for 10 hours. After the reaction was completed, it was allowed to cool at room temperature, and then poured into a beaker filled with 200 mL of deionized water to obtain a light yellow precipitate. After filtering, it was continuously washed with deionized water for 2 to 3 times and dried at 60° C. to obtain a benzoxazine-containing amine curing agent 2, whose structural formula is as follows:

[0069]

[0070] Among them, the average n is 12.49.

[0071] (2) The obtained benzoxazine-containing amine curing agent 2 and tetramethyl bisphenol A diglycidyl ether are uniformly mixed in a ratio of active hydrogen to epoxy group of 1:1, and then heated to 90°C in a blast oven for mixing, and 0.1% of the total mass of dodecyl tertiary amine is added to the mixture for pre-curing, and finally cured at 120°C for 2h, then at 140°C for 2h, then at 160°C for 2h, then at 180°C for 2h, and finally at 200°C for 2h to obtain an epoxy resin cured product.

[0072] Performance Testing:

[0073] The glass transition temperature (Tg) is 275°C, the tensile strength is 82MPa, the limiting oxygen index (LOI) is 31.3%, the UL-94 vertical burning test reaches V-0 level, and the peak heat release rate (PHRR) is 78MJ / m 2 , total heat release (THR) is 41KW / m 2 , the total smoke release (TSP) is 1.83m 2 , CO generation is 0.069g / g, CO2 generation is 1.31g / g, and the maximum smoke density (Ds max ) is 58MJ / m 3 .

[0074] Example 3

[0075] (1) Soybean aglycone (0.01 mol, 2.542 g), tetraethylenepentamine (0.01 mol, 1.893 g) and paraformaldehyde (0.04 mol, 1.201 g) were placed in a single-mouth bottle with a magnetic stirrer, mixed and dissolved in 50 mL of dioxane at 60° C., and heated under reflux at 110° C. for 12 hours. After the reaction was completed, it was allowed to cool at room temperature, and then poured into a beaker containing 200 mL of deionized water to obtain a yellow precipitate. After filtering, it was continuously washed with deionized water for 2 to 3 times and dried at 60° C. to obtain a benzoxazine-containing amine curing agent 3, whose structural formula is as follows:

[0076]

[0077] Among them, the average n is 13.83.

[0078] (2) The obtained benzoxazine-containing amine curing agent 3 and 4,4'-dihydroxybenzophenone diglycidyl ether were uniformly mixed in a ratio of active hydrogen to epoxy group of 2:3, and then heated to 100°C in a blast oven for mixing, and 0.05% of the total mass of the mixture was added with zinc acetylacetonate for pre-curing, and finally cured at 120°C for 2h, then at 140°C for 2h, then at 160°C for 2h, then at 180°C for 2h, and finally at 200°C for 2h to obtain an epoxy resin cured product.

[0079] Performance Testing:

[0080] The glass transition temperature (Tg) is 265°C, the tensile strength is 81MPa, the limiting oxygen index (LOI) is 32.6%, the UL-94 vertical burning test reaches V-0 level, and the peak heat release rate (PHRR) is 72MJ / m 2 , total heat release (THR) is 38KW / m 2 , the total smoke release (TSP) is 1.26m 2 , CO generation is 0.063g / g, CO2 generation is 1.24g / g, and the maximum smoke density (Ds max ) is 54MJ / m 3 .

[0081] Example 4

[0082] (1) Soybean aglycone (0.01 mol, 2.542 g), pentaethylenehexamine (0.01 mol, 2.324 g) and paraformaldehyde (0.04 mol, 1.201 g) were placed in a single-mouth bottle with a magnetic stirrer, mixed and dissolved in 50 mL of DMF at 60° C., and heated under reflux at 130° C. for 15 hours. After the reaction was completed, it was allowed to cool at room temperature, and then poured into a beaker filled with 200 mL of deionized water to obtain a yellow precipitate. After filtering, it was continuously washed with deionized water for 2 to 3 times and dried at 60° C. to obtain a benzoxazine-containing amine curing agent 4, whose structural formula is as follows:

[0083]

[0084] Among them, the average n is 15.46.

[0085] (2) The obtained benzoxazine-containing amine curing agent 4 and tetraethyl bisphenol F diglycidyl ether are uniformly mixed in a ratio of active hydrogen to epoxy group of 1:2, and then heated to 90°C in a blast oven for mixing, and 0.1% of the total mass of dodecyl amine is added to the mixture for pre-curing, and finally cured at 120°C for 2h, then at 140°C for 2h, then at 160°C for 2h, then at 180°C for 2h, and finally at 200°C for 2h to obtain an epoxy resin cured product.

[0086] Performance Testing:

[0087] The glass transition temperature (Tg) is 274°C, the tensile strength is 90MPa, the limiting oxygen index (LOI) is 30.8%, the UL-94 vertical burning test reaches V-0 level, and the peak heat release rate (PHRR) is 63MJ / m 2 , total heat release (THR) is 33KW / m 2 , the total smoke release (TSP) is 1.93m 2 , CO generation is 0.072g / g, CO2 generation is 1.37g / g, and the maximum smoke density (Ds max ) is 60MJ / m 3 .

[0088] Comparative Example 1

[0089] The preparation method is the same as that of Example 1, except that the benzoxazine-containing amine curing agent 1 is replaced with a common curing agent 4,4-diaminodiphenylmethane, and the 4,4-diaminodiphenylmethane and bisphenol A diglycidyl ether are uniformly mixed in a ratio of active hydrogen to epoxy group of 1:1.

[0090] Performance Testing:

[0091] The glass transition temperature (Tg) is 168°C, the tensile strength is 70MPa, the limiting oxygen index (LOI) is 19.1%, the UL-94 vertical burning test reaches V-2 level, and the peak heat release rate (PHRR) is 450MJ / m 2 , total heat release (THR) is 176KW / m 2 , the total smoke release (TSP) is 15.6m 2 , CO generation is 0.28g / g, CO2 generation is 4.86g / g, and the maximum smoke density (Ds max ) is 218MJ / m 3 .

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A benzoxazine-containing amine curing agent, characterized in that: It includes the following structural units: Among them, R is selected from For the connection location.

2. The method for preparing a benzoxazine-containing amine curing agent according to claim 1, characterized in that: The following steps are involved: Polyethylene polyamine, organic solvent, soybean aglycone and paraformaldehyde are mixed and then subjected to Mannich reaction to prepare an amine curing agent containing benzoxazine.

3. The method for preparing a benzoxazine-containing amine curing agent according to claim 2, characterized in that: The polyethylene polyamine is one of diethylenetriamine, triethylenetetramine, tetraethylenepentamine and pentaethylenehexamine.

4. The method for preparing a benzoxazine-containing amine curing agent according to claim 2, characterized in that: The molar ratio of the polyethylene polyamine, daidzein and paraformaldehyde is 1:1-1.3:4-4.

8.

5. The method for preparing a benzoxazine-containing amine curing agent according to claim 2, characterized in that: The Mannich reaction temperature is 90-150° C., and the reaction time is 8-24 hours.

6. An epoxy resin composition comprising an epoxy resin precursor, the benzoxazine-containing amine curing agent according to claim 1 and a curing accelerator, wherein the ratio of the epoxy equivalent value in the epoxy resin precursor to the active hydrogen equivalent value of the benzoxazine-containing amine curing agent is 10:1 to 10.

7. The epoxy resin composition according to claim 6, characterized in that The epoxy resin precursor is selected from any of the following structures: Wherein, X, Y and Z are each independently selected from any of the following structures: R1, R2, R3 and R4 are each independently selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy, phenyl, phenoxy or C3-C7 cycloalkyl, is the connection location; The curing accelerator is at least one of tertiary amine, tertiary amine salt, quaternary ammonium salt, imidazole compound, organic phosphorus compound, acetylacetone metal salt, carboxylic acid metal salt and boron trifluoride amine complex.

8. An epoxy resin cured product, characterized in that: The cured product is obtained by gradient curing the epoxy resin composition. The starting temperature of the gradient curing is 120°C and the end temperature is 200°C.

9. The epoxy resin cured product according to claim 8, characterized in that: The limiting oxygen index of the epoxy resin cured product is 30% to 35%, and the flame retardancy reaches V-0 level; the maximum smoke density of the epoxy resin cured product is 50 to 70 MJ / m 3 , CO generation is 0.06~0.08g / g.

10. Use of the epoxy resin cured product according to claim 8 or 9 in the fields of composite materials and electronic packaging materials.

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