Flame-retardant epoxy resin composite material and preparation method thereof

Abstract

The invention discloses a flame-retardant epoxy resin composite material and a preparation method thereof. The composite material comprises two-dimensional nano material core-shell structure composite particles coated with polyphosphazene, the two-dimensional nano material core-shell structure composite particles are dispersed in an epoxy resin matrix, and a composite material system is formed by the two-dimensional nano material core-shell structure composite particles, a curing agent, a silane coupling agent and polyetherimide. According to the composite material, the problems of contradiction between flame retardance and mechanical property, nano dispersion, toxicity, durability and the like in the traditional epoxy resin flame-retardant technology are solved, and the synergistic improvement of the flame retardance and the mechanical property of the epoxy resin is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of flame-retardant modification of high polymer materials, and particularly relates to a composite material of epoxy resin modified by polyphosphazene-coated nanoparticles and a preparation method thereof, and is particularly suitable for the fields of aerospace composites, electronic packaging materials and the like which have strict requirements on flame-retardant performance and mechanical performance. BACKGROUND

[0002] Currently, there are many technical bottlenecks in the traditional flame-retardant technology of epoxy resin. Flame-retardant-mechanical performance contradiction: additive flame retardants (such as aluminum hydroxide) need a high filling amount (> 30wt%), which will cause a significant increase in the viscosity of the resin, and further cause a significant decrease in the mechanical performance of the epoxy resin; Nanodispersion problem: nanometer flame retardants (such as MXene) are prone to agglomeration in the epoxy resin matrix, which seriously affects the flame-retardant efficiency. According to the literature report (ACS Appl. Mater. Interfaces 2021, 13, 2568), the epoxy system with 5wt% of traditional physical blending MXene can only reach UL-94 V-2 level, and the LOI value is ≤26%; Toxicity and durability problem: halogen-based flame retardants have a great environmental risk in use and disposal, and phosphorus-based flame retardants are prone to migration and precipitation, which affects the long-term performance of the material. Polyphosphazene (PPZ) is a new type of inorganic-organic hybrid material, which has the following characteristics: the main chain is composed of alternating P and N atoms, and a dense carbon layer can be formed at high temperature; the side chain can be modified to have flame-retardant and interfacial reinforcing effects; and the decomposition temperature is > 300℃, which is matched with the processing temperature of the epoxy resin. However, there is no report on the use of polyphosphazene-coated nanoparticles for the synergistic modification of epoxy resin to simultaneously solve the above technical bottlenecks. SUMMARY

[0003] The application aims to provide a flame-retardant epoxy resin composite material and a preparation method thereof, to solve the flame-retardant-mechanical performance contradiction, nanodispersion problem and toxicity and durability problem in the traditional flame-retardant technology of epoxy resin, and to realize the synergistic improvement of the flame-retardant performance and mechanical performance of the epoxy resin. According to one aspect of the application, a flame-retardant epoxy resin composite material is provided, which comprises polyphosphazene-coated two-dimensional nanomaterial core-shell structure composite particles, the composite particles are dispersed in an epoxy resin matrix, and the composite particles, a curing agent, a silane coupling agent and a polyetherimide together constitute a composite material system.

[0004] Preferably, the composite particles are of a core-shell structure, the shell layer is aminated polyphosphazene with a thickness of 10-20nm, and the core layer is a two-dimensional nanomaterial; the shell layer is coated on the surface of the core layer by electrostatic self-assembly.

[0005] Preferably, the two-dimensional nanomaterial is selected from MXene, BNNS or MoS2; the thickness of the two-dimensional nanomaterial is 1-5 nm, the lateral size is 0.5-2 pm, and the specific surface area is >200 m2 / g.

[0006] Preferably, the composite material comprises the following raw materials, and the content of each raw material is as follows in parts by weight: epoxy resin 100 parts Curing agent 25-30 parts Composite particles 3-8 parts Silane coupling agent 0.5-1 part Polyetherimide 5-10 parts.

[0007] Preferably, the epoxy resin is bisphenol A diglycidyl ether or bisphenol F epoxy resin; the curing agent is 2,4-diaminodiphenylmethane or diamino diphenyl sulfone; and the silane coupling agent is gamma-glycidyl ether propyl trimethoxysilane or gamma-aminopropyl triethoxysilane.

[0008] The flame-retardant epoxy resin composite of the present application provides a core-shell structure of a flame-retardant unit, which is a polyphosphazene-coated two-dimensional nanomaterial core-shell structure composite particle. The core layer of the composite particle uses a two-dimensional nanomaterial, including MXene, BNNS or MoS2, with a thickness of 1-5 nm and a lateral size of 0.5-2 μm, and a specific surface area > 200 m² / g. The thickness of the core layer of 1-5 nm can ensure the integrity of the two-dimensional layered structure of the nanomaterial, which can not only provide sufficient sheet “barrier effect” (delaying heat / mass transfer), but also form strong interaction with the polyphosphazene shell layer through edge defects. The lateral size of 0.5-2 μm can form a “network-like dispersion” in the resin matrix, which can not only avoid stress concentration caused by excessive size, but also improve the crack propagation resistance of the material through sheet lapping. Controlling the specific surface area > 200 m² / g can provide sufficient surface active sites to form high-density bonding with the amino groups of the aminated polyphosphazene, ensuring the stability of the core-shell structure and enhancing the interfacial adhesion with the resin. The shell layer is aminated polyphosphazene (PPZ-NH2), which is coated on the core layer by electrostatic self-assembly, and the shell layer has a thickness of 10-20 nm. Selecting aminated polyphosphazene as the shell layer, the amino groups (-NH2) and the hydroxyl groups (-OH) and epoxy groups on the surface of the two-dimensional nanomaterial are tightly combined through electrostatic self-assembly / chemical bonding, which can solve the problem of nanomaterial agglomeration and enhance the adhesion with the resin matrix. The molecular chain has excellent flexibility, and the shell layer thickness (10-20 nm) can be precisely controlled by the polymerization time, which can not only ensure the effective loading of flame-retardant elements, but also avoid the decrease of mechanical properties caused by excessive thickness of the shell layer. The core-shell structure composite particle constructs a gas phase flame-retardant-coagulation phase flame-retardant synergistic flame-retardant system. The gas phase flame-retardant mainly decomposes PPZ during combustion, releases phosphorus-containing free radicals, captures active free radicals generated during combustion, and thus inhibits the combustion reaction. The coagulation phase flame-retardant is the growth of a directional carbon layer induced by the nanometer core, and PPZ promotes the formation of a P-N-Si crosslinked network to enhance the compactness and stability of the carbon layer, thereby improving the flame-retardant effect.

[0009] The flame-retardant epoxy resin composite of the present application is a polyphosphazene-coated two-dimensional nanomaterial core-shell structure composite particle dispersed in an epoxy resin matrix, which, together with a curing agent, a silane coupling agent and a polyetherimide, forms a composite material system.

[0010] The epoxy resin is used as the matrix material, and the content is 100 parts by weight. In the present application, the epoxy resin is bisphenol A diglycidyl ether (DGEBA) or bisphenol F epoxy resin (DGEBF), which has strong reactivity with the curing agent and excellent mechanical properties of the cured product. Preferably, the epoxy resin is DGEBA, which has lower cost, mature technology and better compatibility with the core-shell particle of the present application, as verified by the examples.

[0011] The curing agent is used to initiate the cross-linking reaction of the epoxy resin, and the curing agent is selected from 2,4-diaminodiphenyl methane (DDM) or diaminodiphenyl sulfone (DDS). The aromatic amine curing agent has high cross-linking density after high-temperature curing, and the glass transition temperature (Tg) can reach above 180°C, which is suitable for the step curing process of the application. In some embodiments, the curing agent is preferably DDM, which has better solubility at room temperature, and the toughness of the cured product is better after optimization of the molar ratio of the reaction with the epoxy resin. The content is 25-30 parts; preferably, 27 parts.

[0012] In some specific preferred embodiments, the epoxy resin is DGEBA, the curing agent is DDM, and the molar ratio of DDM to DGEBA is controlled to be 1:4, and the curing is the most complete.

[0013] The main role of the core-shell structure composite particles is to play a synergistic effect of flame retardation and toughening. The particles form a "percolation network" in the matrix, which not only plays a role in flame retardation but also improves toughness. The content is 3-8 parts, and when the content is less than 3 parts, the flame retardation is insufficient; and when the content is greater than 8 parts, the particles are severely agglomerated, and the mechanical properties are suddenly reduced. Preferably, the content is 3-6 parts. When the content is 6-8 parts, the flame retardation is further improved, but the mechanical properties begin to decrease. In some specific embodiments, the core-shell structure composite particles are PPZ@MXene core-shell particles.

[0014] The silane coupling agent is used to improve the interfacial compatibility between the components, and the molecule contains an epoxy group and a methoxy group. The epoxy group reacts with the resin matrix, and the methoxy group is combined with the surface hydroxyl group of the nanomaterial after hydrolysis, thereby improving the interface in two directions. The silane coupling agent is selected from γ-glycidyl ether propyl trimethoxysilane (KH560) or γ-aminopropyl triethoxysilane (KH550). In some specific embodiments, the silane coupling agent is preferably KH560, in which the epoxy group reacts more directly with the resin, and the interfacial modification efficiency is tested to be 15% higher. In the present application, the interfacial modification effect is best when the content of the silane coupling agent is 0.5-1 part, the modification is insufficient when the content is too low; and when the content is too high, the coupling agent itself is agglomerated (forming a siloxane gel), which can cause the material properties to decrease. Preferably, the content is 0.5-0.8 parts.

[0015] Polyetherimide is used as a toughening phase to mainly improve the toughness of the epoxy resin. In the present application, the content is 5-10 parts; preferably, 5-8 parts.

[0016] According to a second aspect of the present application, a preparation method of the aforementioned flame-retardant epoxy resin composite material is provided, which comprises the following steps: S1, polyphosphazene in-situ polymerization coating: dispersing two-dimensional nanomaterials in a solvent, adding an amino-containing polyphosphazene solution, reacting at 60-80°C for 3-5h, and then collecting the polyphosphazene-coated two-dimensional nanomaterial core-shell structure composite particles by centrifugation; S2, resin compounding: the composite particles prepared in step S1 are mixed with a silane coupling agent, ultrasonically dispersed, then an epoxy resin and a polyetherimide are mixed uniformly, a curing agent is finally added, and vacuum degassing treatment is performed; S3, curing: the composite resin prepared in step S2 is subjected to stepwise curing.

[0017] In step S1, 60-80°C is a suitable temperature (initiator activity window) for in-situ polymerization of the polyphosphazene, and 3-5h can ensure complete coating of the shell. If the temperature is too low and the reaction time is too short, the polymerization will not be complete; if the temperature is too low and the reaction time is too long, the particles will agglomerate, resulting in fluctuations in the performance of the composite material. In some specific embodiments, step S1 is carried out at 60°C for 4h.

[0018] In some embodiments, the solvent is ethanol; the amino-polyphosphazene solution has a mass concentration of 5%-15% (solvent is ethanol). A concentration that is too low will result in incomplete coating of the shell, the nanomaterial will be easily exposed, and the loading of the flame-retardant element will be insufficient; a concentration that is too high will result in a shell that is too thick (>20nm), and a slightly larger shell thickness will result in a decrease in the dispersibility of the core-shell particles, leading to a decrease in the interfacial adhesion of the core-shell particles and the resin. In some preferred embodiments, the concentration is 10%: the shell thickness is moderate, the uniformity of the coating is best, and the synergy of the flame retardancy and mechanical properties is optimal. The amount of two-dimensional nanomaterial is 0.5-2 parts (based on 100 parts of epoxy resin) by weight. This range ensures uniform dispersion of the nanomaterial in the matrix; if it is less than 0.5 parts, the barrier effect of the sheet will be insufficient, and if it is more than 2 parts, the nanomaterial will easily agglomerate, resulting in a decrease in the mechanical properties.

[0019] In step S1, the reaction pH is 8-9. If the pH is <8, the polymerization rate of the polyphosphazene will be slow, and the shell coating will not be complete. If the pH is >9, side reactions (such as oxidation of the amino group) will be easily initiated, the crosslinking degree of the polyphosphazene molecular chain will be too high, and the shell brittleness will increase. In some specific embodiments, the pH is 9.

[0020] Preferably, in step S2, the composite particles are mixed with a silane coupling agent, and ultrasonically dispersed at 30-40kHz for 30-40min. In some specific embodiments, ultrasonic dispersion is carried out at 40kHz for 30min.

[0021] Preferably, in step S3, the stepwise curing is specifically curing at 75-85°C for 1-2h, at 110-120°C for 1.5-2h, and at 175-185°C for 3-5h. In some specific embodiments, the stepwise curing is curing at 80°C for 2h, at 120°C for 2h, and at 180°C for 4h. Low-temperature preliminary curing avoids too rapid volume shrinkage, medium-temperature promotes uniformity of crosslinking, and high-temperature improves crosslinking density. Selecting a stepwise curing method can achieve better curing results.

[0022] Compared with the prior art, the flame-retardant epoxy resin composite material of the present application can achieve V-0 level flame-retardant standard, the limiting oxygen index (LOI) is increased to 34%, and the peak heat release rate is reduced to 210 kW / m2, which significantly improves the flame-retardant performance compared with pure epoxy resin. The mechanical properties are greatly improved, and the bending strength, fracture toughness (KIC) and glass transition temperature (Tg) are all obviously improved. In addition, through the cone calorimetry test, the residual carbon rate of the flame-retardant epoxy resin composite material system of the present application is increased from 8% of pure epoxy resin to 39%; and XPS analysis shows that P-O-C (532.3 eV) and Si-O-P (103.5 eV) bonds exist in the residual carbon; SEM observation shows that a honeycomb-shaped multi-layer carbon layer is formed after combustion, which can effectively block heat and oxygen and enhance the flame-retardant effect. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions of the present application will be described clearly and completely below in combination with specific embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in any manner without conflict.

[0024] In some optional embodiments, a flame-retardant epoxy resin composite material is provided, comprising polyphosphazene-coated two-dimensional nanomaterial core-shell structure composite particles, the shell layer of which is aminated polyphosphazene with a thickness of 10-20 nm; and the two-dimensional nanomaterial core layer is coated on the surface of the two-dimensional nanomaterial core layer by electrostatic self-assembly.

[0025] In some optional embodiments, the two-dimensional nanomaterial is selected from MXene, BNNS, or MoS2; the thickness is 1-5 nm, the lateral size is 0.5-2 μm, and the specific surface area is >200 m² / g.

[0026] In some optional embodiments, the composite material comprises the following raw materials, and the content of each raw material is as follows in parts by weight: epoxy resin 100 parts, curing agent 25-30 parts, core-shell structure composite particles 3-8 parts, silane coupling agent 0.5-1 part, and polyetherimide 5-10 parts.

[0027] In some optional embodiments, the epoxy resin is DGEBA; the curing agent is DDM; and the silane coupling agent is KH560.

[0028] In some optional embodiments, a preparation method of the above flame-retardant epoxy resin composite material is provided, comprising the following steps: S1, in-situ polyphosphazene polymerization coating: disperse the two-dimensional nanomaterial in ethanol, add a polyaminophosphazene solution with a mass concentration of 5%-15%, the reaction pH value is 8-9, and the reaction is carried out at 60-80°C for 3-5h; then collect the polyphosphazene-coated two-dimensional nanomaterial core-shell structure composite particles by centrifugation; S2, resin compounding: mix the composite particles prepared in step S1 with a silane coupling agent, ultrasonically disperse for 30-40min at 30-40kHz, then mix evenly with an epoxy resin and a polyetherimide, finally add a curing agent and perform vacuum degassing treatment; S3, curing: carry out stepwise curing of the composite resin prepared in step S2, specifically, curing at 75-85°C for 1-2h, curing at 110-120°C for 1.5-2h, and curing at 175-185°C for 3-5h.

[0029] In order to more clearly explain the technical solutions of the present application, part of the specific embodiments of the flame-retardant epoxy resin composite material of the present application are listed below.

[0030] Example 1 Raw material ratio of flame-retardant epoxy resin composite (parts by weight): Epoxy resin (DGEBA) 100 parts Curing agent (DDM) 27 parts PPZ@MXene composite particles 3 parts (core layer MXene thickness 3nm, lateral size 1μm, shell layer PPZ-NH2 thickness 15nm) Silane coupling agent (KH560) 0.5 parts Polyetherimide (PEI) 5 parts Preparation steps: Disperse MXene in ethanol, add PPZ-NH2 solution (pH=9, concentration 10%), stir at 60°C for 4h, and collect PPZ@MXene composite particles by centrifugation. Ultrasonically disperse PPZ@MXene with KH560 (40kHz, 30min), then mix with epoxy resin and PEI, finally add DDM and vacuum degassing. Stepwise curing: 80°C / 2h + 120°C / 2h + 180°C / 4h.

[0031] Example 2 Raw material ratio of flame-retardant epoxy resin composite (parts by weight) Epoxy resin (DGEBA) 100 parts Curing agent (DDM) 27 parts PPZ@BNNS composite particles 6 parts (core layer BNNS thickness 2 nm, lateral size 1.5 μm, shell layer PPZ-NH2 thickness 18 nm) Silane coupling agent (KH560) 0.8 parts Polyetherimide (PEI) 8 parts; Preparation steps are the same as Example 1.

[0032] Example 3 Raw material ratio of flame-retardant epoxy resin composite (parts by weight): Epoxy resin (DGEBA) 100 parts Curing agent (DDM) 30 parts PPZ@MXene composite particles 8 parts (core layer MXene thickness 4 nm, lateral size 2 μm, shell layer PPZ-NH2 thickness 15 nm) Silane coupling agent (KH560) 1 part Polyetherimide (PEI) 10 parts; Preparation steps: Disperse MXene in ethanol, add PPZ-NH2 solution (pH = 9, concentration 10%), stir at 60°C for 4h, centrifuge to collect PPZ@MXene composite particles. Ultrasonically disperse PPZ@MXene with KH560 (40 kHz, 30 min), then mix with epoxy resin and PEI, finally add DDM, vacuum degassing. Step curing: 80°C / 2h + 120°C / 2h + 180°C / 4h.

[0033] Example 4 Raw material ratio of flame-retardant epoxy resin composite (parts by weight): Epoxy resin (DGEBA) 100 parts Curing agent (DDM) 26 parts PPZ@MXene composite particles 5 parts (core layer MXene thickness 4 nm, lateral size 2 μm, shell layer PPZ-NH2 thickness 15 nm) Silane coupling agent (KH560) 0.6 parts Polyetherimide (PEI) 7 parts; Preparation steps: Disperse MXene in ethanol, add PPZ-NH2 solution (pH = 9, concentration 12%), stir at 60°C for 4h, centrifuge to collect PPZ@MXene composite particles. Ultrasonically disperse PPZ@MXene with KH560 (40 kHz, 30 min), then mix with epoxy resin and PEI, finally add DDM, vacuum degassing. Staged curing: 80°C / 2h + 120°C / 2h + 180°C / 4h.

[0034] To further illustrate the beneficial effects of the present application, composite materials with different flame retardant additives and different proportions and processes were selected as comparative examples (Comparative Examples 1-3) for performance comparison tests.

[0035] Comparative Example 1 Raw material ratio (parts by weight) Epoxy resin (DGEBA) 100 parts Curing agent (DDM) 27 parts Uncoated MXene 3 parts PPZ 3 parts Silane coupling agent (KH560) 0.5 parts Polyetherimide (PEI) 5 parts Preparation steps Uncoated MXene, PPZ, and KH560 were ultrasonically dispersed (40 kHz, 30 min), then mixed with epoxy resin and PEI, and finally DDM was added. After vacuum degassing, staged curing (80°C / 2h + 120°C / 2h + 180°C / 4h) was performed.

[0036] Comparative Example 2 Raw material ratio (parts by weight) Epoxy resin (DGEBA) 100 parts Curing agent (DDM) 27 parts Common aluminum hydroxide flame retardant 30 parts Silane coupling agent (KH560) 0.5 parts Polyetherimide (PEI) 5 parts Preparation steps Aluminum hydroxide and KH560 were ultrasonically dispersed (40 kHz, 30 min), then mixed with epoxy resin and PEI, and finally DDM was added. After vacuum degassing, staged curing (80°C / 2h + 120°C / 2h + 180°C / 4h) was performed. Comparative Example 3 Raw material ratio (parts by weight) of flame-retardant epoxy resin composite: Epoxy resin (DGEBA) 100 parts Curing agent (DDM) 24 parts PPZ@MXene composite particles 9 parts (core layer MXene thickness 3 nm, lateral size 1 μm, shell layer PPZ-NH2 thickness 15 nm) Silane coupling agent (KH560) 1.5 parts Polyetherimide (PEI) 11 parts Preparation steps: MXene was dispersed in ethanol, and PPZ-NH2 solution (pH = 9, concentration of 10%) was added, stirred at 60°C for 4h, and PPZ@MXene composite particles were collected by centrifugation. PPZ@MXene was ultrasonically dispersed (40kHz, 30min), then mixed with epoxy resin and PEI, and finally DDM was added and vacuum degassed. Step curing: 80°C / 2h + 120°C / 2h + 180°C / 4h.

[0037] Table 1 shows the performance test results of each example and comparative example.

[0038] Table 1 Performance test results of examples and comparative examples

[0039] From the test results in the above table, each example takes different types and amounts of core-shell structure composite particles as the core, combined with an optimized preparation process, and the prepared flame-retardant epoxy resin composite material realizes excellent flame retardance and mechanical properties at a low core-shell structure composite particle addition amount, which is specifically reflected in: the UL-94 test reaches V-0 level, the LOI is increased to 34% at most, the peak heat release rate is reduced to 210kW / m² at most; the bending strength is increased by 21%-34.7% compared with traditional flame-retardant epoxy, and the fracture toughness is increased by 47%-65.2%. Compared with the deficiencies of low flame-retardant level and decreased mechanical properties of each comparative example, the flame-retardant epoxy resin composite material of the present application realizes the comprehensive improvement of flame-retardant performance and mechanical properties.

[0040] In summary, the flame-retardant epoxy resin composite material involved in the present application realizes the dual improvement of flame retardance and mechanical properties at a low addition amount through core-shell structure design, synergistic flame-retardant system and optimized process, and the performance is far superior to traditional schemes and physical mixing control groups, which has significant technical advantages and application value.

[0041] The above examples are only used to illustrate the technical solutions of the present application, but not to limit them. Although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent substitutions for part of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the examples of the present application.

[0042] It should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the same. Although the present application has been described in detail with reference to the foregoing examples, it will be appreciated by those skilled in the art that modifications can be made to the technical solutions described in the foregoing examples, or some of the technical features thereof can be replaced by equivalent features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A flame-retardant epoxy resin composite material, characterized by comprising: The application discloses a polyphosphazene-coated two-dimensional nanomaterial composite particle, which is dispersed in an epoxy resin matrix to form a composite material system together with a curing agent, a silane coupling agent and a polyetherimide.

2. The flame retardant epoxy resin composite according to claim 1, characterized in that, The composite particle has a core-shell structure, the shell layer is an aminated polyphosphazene with a thickness of 10-20 nm, and the core layer is a two-dimensional nanomaterial.

3. The flame retardant epoxy resin composite according to claim 2, characterized in that, The two-dimensional nanomaterial is selected from MXene, BNNS or MoS2, has a thickness of 1-5 nm, a lateral size of 0.5-2 mu m and a specific surface area of more than 200 m2 / g.

4. The flame retardant epoxy resin composite according to claim 1, characterized in that, The composite material comprises the following raw materials in parts by weight, and the content of each raw material is: epoxy resin 100 parts curing agent 25-30 parts composite particle 3-8 parts silane coupling agent 0.5-1 part polyetherimide 5-10 parts.

5. The flame-retardant epoxy resin composite material according to claim 1, characterized in that, the epoxy resin is bisphenol A diglycidyl ether or bisphenol F epoxy resin; the curing agent is 2,4-diaminodiphenylmethane or diaminodiphenyl sulfone; the silane coupling agent is gamma-glycidyl ether oxypropyl trimethoxysilane or gamma-aminopropyl triethoxysilane.

6. A process for the preparation of a flame-retardant epoxy resin composite material as claimed in any one of claims 1-5, characterized in that, The method comprises the following steps: S1, polyphosphazene in-situ polymerization coating: dispersing two-dimensional nanomaterials in a solvent, adding an aminated polyphosphazene solution, reacting at 60-80 DEG C for 3-5 h, and then collecting the polyphosphazene-coated two-dimensional nanomaterial core-shell structure composite particles by centrifugation; S2, resin compounding: mixing the composite particles prepared in step S1 with a silane coupling agent, performing ultrasonic dispersion, then uniformly mixing epoxy resin and polyetherimide, finally adding a curing agent and performing vacuum degassing treatment; S3, curing: performing step-by-step curing on the composite resin prepared in step S2.

7. The method of producing a flame-retardant epoxy resin composite material according to claim 6, characterized by, In step S1, the solvent is ethanol; the mass concentration of the aminated polyphosphazene solution is 5%-15%; and the reaction pH value is 8-9.

8. The method for preparing the flame-retardant epoxy resin composite material according to claim 6, characterized in that, In step S2, the composite particles are mixed with the silane coupling agent, and ultrasonic dispersion is performed at 30-40 kHz for 30-40 min.

9. The method for preparing the flame-retardant epoxy resin composite material according to claim 6, characterized in that, In step S3, the step-by-step curing is specifically curing at 75-85 DEG C for 1-2 h, curing at 110-120 DEG C for 1.5-2 h and curing at 175-185 DEG C for 3-5 h.

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