High-thermal-conductivity epoxy resin composite material and preparation method thereof

Abstract

The invention relates to the technical field of polymer composite materials, in particular to a high-thermal-conductivity epoxy resin composite material and a preparation method thereof. The high-thermal-conductivity epoxy resin composite material is prepared from the following raw material components in parts by weight: 100 parts of epoxy resin, 10 to 50 parts of hexagonal boron nitride nanosheets (BNNS), 10 to 50 parts of hexagonal boron nitride sheets (BN), 3 to 5 parts of graphene hybrid boron nitride and 20 to 50 parts of a curing agent. The invention relates to an epoxy resin-based composite material with excellent heat-conducting property, which is prepared by taking a hexagonal boron nitride nanosheet (BNNS), a hexagonal boron nitride sheet (BN) and graphene hybridized boron nitride as mixed filler. The composite material disclosed by the invention can be widely applied to the fields requiring high heat-conducting property, such as electronic packaging, heat dissipation devices, aerospace and automobile industry, and is particularly suitable for manufacturing thermal interface materials (TIMs).

Description

Technical Field

[0001] The invention belongs to the technical field of polymer composite materials, and particularly relates to a high thermal conductivity epoxy resin composite material and a preparation method thereof. Background Art

[0002] Epoxy resins (EP) are widely used as thermal management and protection materials due to their excellent electrical insulation properties, excellent dimensional stability, good mechanical properties, excellent chemical resistance, and low cure shrinkage. Hexagonal boron nitride has been shown to be an excellent material for improving the mechanical and thermal conductivity of EPs due to its high thermal conductivity (300-2000 W / m·K), low dielectric constant, significant voltage breakdown strength (about 12 MV / cm), and outstanding mechanical properties (Young's modulus: 1 TPa). However, the inherent brittle fracture and poor thermal conductivity of cured epoxies have greatly limited their applications in the real world.

[0003] Therefore, there is an urgent need for an epoxy resin composite material with high thermal conductivity to improve the thermal conductivity of epoxy resin. Summary of the invention

[0004] The object of the present invention is to provide a high thermal conductivity epoxy resin composite material and a preparation method thereof, so as to solve the technical problem of poor thermal conductivity of epoxy resin in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The technical solution provided by the present invention is as follows:

[0007] In a first aspect, the present invention provides a high thermal conductivity epoxy resin composite material, which specifically includes the following components in parts by weight: 100 parts of epoxy resin, 10-50 parts of hexagonal boron nitride nanosheets (BNNS), 10-50 parts of hexagonal boron nitride sheets (pristine BN), 3-5 parts of graphene hybrid boron nitride, and 20-50 parts of a curing agent.

[0008] Preferably, the weight ratio of the BNNS to pristine BN is 1:(0.5-1.5).

[0009] Preferably, the curing agent includes at least one of m-phenylenediamine curing agent and diaminodiphenyl sulfone curing agent.

[0010] In a second aspect, the present invention also provides a method for preparing a high thermal conductivity epoxy resin composite material, comprising the following steps:

[0011] Step (1) 10-50 parts of BNNS and 10-50 parts of pristine BN, 100 parts of epoxy resin and 3-5 parts of graphene hybrid boron nitride are mixed, stirred at a speed of 2000-2500 rpm for 3-7 minutes, mixed and stirred evenly, and cooled to room temperature;

[0012] Step (2) adding 20-50 parts of curing agent, stirring at a rotation speed of 2000-2500 rpm for 3-7 minutes, and casting to obtain a high thermal conductivity epoxy resin composite material.

[0013] Preferably, the mixing method of step (1) includes at least one of a premixing method, a masterbatch method, and a solvent-assisted dispersion method.

[0014] Preferably, the premixing method is to premix BNNS and pristine BN at a speed of 2000-2500rpm for 3-7min to make the powders fully contact in a dry state, and then add epoxy resin and graphene hybrid boron nitride to mix and stir evenly; the masterbatch method is to prepare masterbatches of BNNS-epoxy resin and pristine BN-epoxy resin respectively, and then mix the two masterbatches and graphene hybrid boron nitride evenly; the solvent-assisted dispersion method is to mix BNNS, pristine BN, graphene hybrid boron nitride and epoxy resin, add 150mL acetone to assist dispersion, and then evaporate the solvent in vacuum.

[0015] Preferably, the method for preparing the graphene hybrid boron nitride comprises the following steps:

[0016] A1: Disperse 30-60g of modified graphene oxide and 3-6g of BiCl3 in 10-20L N,N-dimethylformamide, stir magnetically for 0.5-1.5min, and then ultrasonically treat for 15-25min, then slowly add 100-200g of modified boron nitride, stir and ultrasonically treat for 15-25min, and then magnetically stir at room temperature for 7-12h, filter, wash the filter residue with water for 3-5 times, and finally freeze-dry for 36-54h to obtain graphene oxide hybrid boron nitride;

[0017] In the above process, the modified boron nitride is grafted onto the modified graphene oxide substrate through an amine-epoxy ring-opening reaction.

[0018] A2: Disperse graphene oxide hybrid boron nitride in water to form a 0.1 g / L dispersion, perform ultrasonic treatment at 30-50 kHz and 150-250 w for 20-40 min to obtain a graphene oxide hybrid boron nitride solution, add 50-100 ml of an ascorbic acid aqueous solution containing 0.02-0.04 g of ascorbic acid to 200-400 ml of the graphene oxide hybrid boron nitride solution, perform ultrasonic treatment at 30-50 kHz and 150-250 w for 1.5-2.5 h, and then stand at room temperature for 36-54 h to obtain graphene hybrid boron nitride.

[0019] In the above process, graphene oxide in graphene oxide hybrid boron nitride is reduced to graphene by ascorbic acid.

[0020] Preferably, the preparation method of the modified boron nitride comprises the following steps:

[0021] S1: In an ice water bath, add 100-200g BN and 2-4g 3-aminopropyltrimethoxysilane to 30-60kg anhydrous ethanol, ultrasonically disperse for 50-70min, then add 4-8kg water and 10-20kg anhydrous ethanol, condense and reflux at 75-85°C for 10-14h, centrifuge while hot, wash the centrifuged solid with water 7-9 times, and freeze-dry for 40-56h to obtain amino boron nitride:

[0022] In the above process, BN is firstly ultrasonically peeled off in ethanol while attaching hydroxyl -OH, and then the amino group (-NH2) in 3-aminopropyltrimethoxysilane is introduced into the BN surface through reaction to obtain amino boron nitride.

[0023] S2: Add 60-90g of amination boron nitride and 60-90g of 3-amino-5-(3-aminophenyl)benzoic acid to 3-4.5L of n-methylpyrrolidone solution and stir for 30-60min, then add 0.2-0.3L of catalyst pyridine and 0.6-0.9mL of stabilizer triphenyl phosphate, and then add 20-30g of LiCl, react at 95-105°C in a N2 nitrogen atmosphere for 10-14h, centrifuge while hot, wash the centrifuged solid with n-methylpyrrolidone solution for 3-5 times, and then freeze-dry for 36-54h to obtain modified boron nitride.

[0024] In the above process, pyridine is used as a catalyst and triphenyl phosphate is used as a stabilizer to dehydrate and condense the -NH2 on the amino boron nitride with the carboxyl group (-COOH) in 3-amino-5-(3-aminophenyl)benzoic acid to form an amide group, so that the -NH2 in benzoic acid is always retained at the end of the molecular chain on the BN surface, and the remaining -COOH in 3-amino-5-(3-aminophenyl)benzoic acid continues to undergo dehydration condensation and amidation reaction with the -NH2 in the benzoic acid structure attached to BN, and this cycle is repeated to gradually generate a hyperbranched structure to obtain modified boron nitride.

[0025] The structural formula of modified boron nitride is as follows:

[0026]

[0027] Preferably, the method for preparing the modified graphene oxide comprises the following steps:

[0028] P1: 53-106g of 2-bromo-3-dodecylthiophene and 46-92g of 2,2,6,6-tetramethylpiperidinylmagnesium chloride and lithium chloride are added to 2-4L of tetrahydrofuran, and stirred at 25°C for 2-4h, and then 2-4L of tetrahydrofuran and 1-2g of bis(triphenylphosphine)nickel chloride are added in sequence, and then stirring is continued at 25°C for 0.5-1.5h, and 0.1mol / L, 1-2L of hydrochloric acid aqueous solution and 1-2L of methanol are added, and filtered, and the filter residue is washed with n-hexane for 3-5 times, and dried under reduced pressure to obtain a modified monomer:

[0029] The structural formula of the modified monomer is as follows:

[0030]

[0031] P2: Add 50-100 g of graphene oxide to 100-200 L of chloroform, ultrasonically treat at 25°C for 0.5-1.5 h, then add 100-200 L of chloroform solution containing 50-100 g of modified monomer, ultrasonically treat at 25°C for 1-3 h, and then evaporate chloroform at 25°C for 2-4 days to obtain modified graphene oxide.

[0032] Through the above technical scheme, the molecular chain structure of the modified monomer has a certain order, which can provide an effective heat conduction path and help the conduction of heat along the molecular chain. The dispersibility of graphene oxide nanoparticles in organic solvents can be improved by modifying graphene oxide. The interface interaction between the modified monomer and graphene can improve the heat conduction efficiency, reduce the interface thermal resistance, promote the effective transfer of heat, and at the same time improve the out-of-plane thermal conductivity and in-plane thermal conductivity of the high thermal conductivity epoxy resin composite material.

[0033] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0034] 1. Pristine BN has poor compatibility with epoxy resin and large fillers are not ideal, while the small size of BNNS leads to a high interface density, thereby generating more phonon scattering centers, which hinders the improvement of thermal conductivity. The present invention adopts a premixed method to prepare a pristine BN and BNNS mixture with a mass ratio of 1:1 to form a unique "fin-like" structure, which helps to reduce the thermal interface resistance of the filler-polymer and filler-filler interfaces. The "fin-like" structure not only connects the pristine BN-BNNS filler, but also the BNNS is attached to the surface and edge of the pristine BN, modifying the pristine BN-epoxy interface. Similar phonon moduli allow pristine BN and BNNS to have good contact, so that they are bonded together in the premix route, and a balance is achieved in terms of the number of interfaces and thermal interface resistance. BNNS with a larger number of flakes helps to improve the thermal conduction density in the composite material without losing the "fluid-like" viscosity characteristics: the integrity of the "fin-like" pristine BN-BNNS structure and the rheological properties of the filler optimize the filler to synergistically enhance thermal conductivity.

[0035] 2. In the present invention, there is a π-π interaction between the modified monomer and graphene oxide, the dodecyl group in the modified monomer improves the compatibility of graphene and epoxy resin, and graphene can improve the in-plane and out-of-plane thermal conductivity of the epoxy resin film: the modified boron nitride hyperbranched structure acts as a "bridge" between boron nitride and epoxy resin, connecting boron nitride and epoxy resin molecules in the form of chemical covalent bonds, thereby enhancing the interface bonding force and dispersibility, and at the same time, the introduced free volume provides a movement space for the molecular chain, and energy can be dissipated through the movement of the molecular chain segments, thereby improving the mechanical properties of the composite material; the free volume inside the modified boron nitride will be reduced due to thermal shrinkage, but it still exists, thereby improving the low-temperature tensile strength of the composite material: the boron nitride and epoxy resin bonded by chemical covalent bonds reduce the The interfacial thermal resistance between the epoxy resins can be reduced, and a complete and continuous thermal conduction path can be easily established to improve the thermal conductivity of the composite material; the modified boron nitride is grafted onto the modified graphene oxide base through an amine-epoxy ring-opening reaction to obtain graphene oxide hybrid boron nitride, and graphene hybrid boron nitride is obtained by reduction: the modified boron nitride of similar size is anchored on the graphene nanosheets to inhibit the restacking of the graphene nanosheets, while the graphene improves the dispersion state of the modified boron nitride. Due to the synergistic effect of graphene and modified boron nitride, a multidimensional network is constructed inside the epoxy matrix, and stress and heat are effectively transferred between the hybrid and the matrix. Based on the covalent interaction between the graphene hybrid boron nitride and the amino, hydroxyl and carboxyl groups of the epoxy resin, the mechanical properties, thermal stability and thermal conductivity of the high thermal conductivity epoxy resin composite material are improved.

[0036] 3. The present invention adds hexagonal boron nitride nanosheets (BNNS), hexagonal boron nitride sheets (pristine BN) and graphene hybrid boron nitride as mixed fillers, and through compounding of different forms of boron nitride, synergistically improves the mechanical properties, thermal stability and thermal conductivity of the thermally conductive epoxy resin composite material: the prepared thermally conductive epoxy resin composite material can be widely used in electronic packaging, heat dissipation devices, aerospace, automotive industry and other fields requiring high thermal conductivity, and is particularly suitable for the preparation of thermal interface materials (TIMs). BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 It is a process flow chart of preparing the high thermal conductivity epoxy resin composite material of the present invention;

[0039] Figure 2 is the x-ray diffraction pattern of pristine BN and BNNS of the present invention;

[0040] Figure 3 is a scanning electron microscope (SEM) micrograph of pristine BN of the present invention;

[0041] Figure 4 is a scanning electron microscope (SEM) micrograph of the BNNS of the present invention;

[0042] Figure 5 is a scanning electron microscope (SEM) micrograph of a high thermal conductivity epoxy resin composite material prepared in Example 4 of the present invention;

[0043] Figure 6 It is a line graph of thermal conductivity and impact strength of the high thermal conductivity epoxy resin composite material of the present invention. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0045] Example 1

[0046] This embodiment discloses a method for preparing modified boron nitride, comprising the following steps:

[0047] S1: In an ice water bath, add 150g BN and 3g 3-aminopropyltrimethoxysilane to 45kg anhydrous ethanol, ultrasonically disperse for 60min, then add 6kg water and 15kg anhydrous ethanol, condense and reflux at 80°C for 12h, centrifuge while hot, wash the centrifuged solid with water 8 times, and freeze-dry for 48h to obtain amino boron nitride;

[0048] S2: Add 75 g of amination boron nitride and 75 g of 3-amino-5-(3-aminophenyl)benzoic acid to 3.8 L of n-methylpyrrolidone solution and stir for 45 min, then add 0.25 L of catalyst pyridine and 0.75 mL of stabilizer triphenyl phosphate, and then add 25 g of LiCl, react at 100 ° C in a N2 nitrogen atmosphere for 12 h, centrifuge while hot, wash the centrifuged solid 4 times with n-methylpyrrolidone solution, and then freeze-dry for 48 h to obtain modified boron nitride.

[0049] Example 2

[0050] This embodiment discloses a method for preparing modified graphene oxide, comprising the following steps:

[0051] P1: 78 g of 2-bromo-3-dodecylthiophene and 69 g of 2,2,6,6-tetramethylpiperidinylmagnesium chloride and lithium chloride were added to 3 L of tetrahydrofuran, and stirred at 25°C for 2-4 h, and then 3 L of tetrahydrofuran and 1.5 g of bis(triphenylphosphine)nickel chloride were added in sequence, and then the stirring was continued at 25°C for 1 h, and 0.1 mol / L, 1.5 L of hydrochloric acid aqueous solution and 1.5 L of methanol were added, and the mixture was filtered, and the filter residue was washed with n-hexane for 4 times, and dried under reduced pressure to obtain a modified monomer;

[0052] P2: 75 g of graphene oxide was added to 150 L of chloroform, and ultrasonically treated at 25 °C for 1 h. Then, 150 L of chloroform solution containing 75 g of modified monomer was added, and ultrasonically treated at 25 °C for 2 h. Then, chloroform was evaporated at 25 °C for 3 days to obtain modified graphene oxide.

[0053] Example 3

[0054] This embodiment discloses a method for preparing graphene hybrid boron nitride, comprising the following steps:

[0055] A1: 45 g of modified graphene oxide and 4.5 g of BiCl3 were dispersed in 15 L of N, N-dimethylformamide, magnetically stirred for 1 min, and then ultrasonically treated for 20 min. Then, 150 g of modified boron nitride was slowly added, stirred and ultrasonically treated for 20 min, and then magnetically stirred for 10 h at room temperature. The filter residue was filtered, washed with water for 4 times, and finally freeze-dried for 48 h to obtain graphene oxide hybrid boron nitride.

[0056] A2: Disperse graphene oxide hybrid boron nitride in water to form a 0.1 g / L dispersion, and ultrasonically treat it at 40 kHz and 200 w for 30 min to obtain a graphene oxide hybrid boron nitride solution. Add 75 mL of an ascorbic acid aqueous solution containing 0.03 g of ascorbic acid to 300 mL of the graphene oxide hybrid boron nitride solution, and ultrasonically treat it at 40 kHz and 200 w for 2 h, and then stand at room temperature for 48 h to obtain graphene hybrid boron nitride.

[0057] Example 4

[0058] See also Figure 1 As shown, this embodiment discloses a method for preparing a high thermal conductivity epoxy resin composite material, comprising the following steps:

[0059] Step (1) 35 g of BNNS and 35 g of pristine BN were premixed at a speed of 2250 rpm for 5 min to allow the powders to fully contact in a dry state, and then mixed with 100 g of epoxy resin and 4 g of graphene hybrid boron nitride prepared in Example 3, and then stirred at a speed of 2250 rpm for 5 min to mix and stir evenly, and then cooled to room temperature;

[0060] In step (2), 38 g of m-phenylenediamine curing agent was added, and the mixture was stirred at a rotation speed of 2250 rpm for 5 min, and cast to obtain a high thermal conductivity epoxy resin composite material.

[0061] Example 5

[0062] See also Figure 1 As shown, this embodiment discloses a method for preparing a high thermal conductivity epoxy resin composite material, comprising the following steps:

[0063] Step (1) 35 g of BNNS and 35 g of pristine BN were added to 50 g of epoxy resin to obtain BNNS-epoxy resin masterbatch and pristine BN-epoxy resin masterbatch, respectively, and then the BNNS-epoxy resin masterbatch, the pristine BN-epoxy resin masterbatch and 4 g of the graphene hybrid boron nitride prepared in Example 3 were stirred at a speed of 2250 rpm for 5 min, and cooled to room temperature;

[0064] In step (2), 38 g of diaminodiphenyl sulfone curing agent was added, and the mixture was stirred at a rotation speed of 2250 rpm for 5 min, and cast to obtain a high thermal conductivity epoxy resin composite material.

[0065] Example 6

[0066] See also Figure 1 As shown, this embodiment discloses a method for preparing a high thermal conductivity epoxy resin composite material, comprising the following steps:

[0067] Step (1) 35 g of BNNS and 35 g of pristine BN, 4 g of graphene hybrid boron nitride prepared in Example 3 and 100 g of epoxy resin were mixed, 150 mL of acetone was added to assist dispersion, and then stirred at a speed of 2250 rpm for 5 min, and the solvent was evaporated in vacuo, and cooled to room temperature;

[0068] In step (2), 38 g of m-phenylenediamine curing agent was added, and the mixture was stirred at a rotation speed of 2250 rpm for 5 min, and cast to obtain a high thermal conductivity epoxy resin composite material.

[0069] Example 7

[0070] See also Figure 1 As shown, this embodiment discloses a method for preparing a high thermal conductivity epoxy resin composite material, comprising the following steps:

[0071] Step (1) 10 g of BNNS and 15 g of pristine BN were premixed at a speed of 2500 rpm for 3 min to allow the powders to fully contact in a dry state, and then mixed with 100 g of epoxy resin and 5 g of graphene hybrid boron nitride prepared in Example 3, and then stirred at a speed of 2500 rpm for 3 min to mix and stir evenly, and then cooled to room temperature;

[0072] In step (2), 20 g of m-phenylenediamine curing agent was added, and the mixture was stirred at a rotation speed of 2500 rpm for 3 min, and cast to obtain a high thermal conductivity epoxy resin composite material.

[0073] Example 8

[0074] See also Figure 1 As shown, this embodiment discloses a method for preparing a high thermal conductivity epoxy resin composite material, comprising the following steps:

[0075] Step (1) 50 g of BNNS and 25 g of pristine BN were premixed at a speed of 2000 rpm for 5 min to allow the powders to fully contact in a dry state, and then mixed with 100 g of epoxy resin and 3 g of graphene hybrid boron nitride prepared in Example 3, and then stirred at a speed of 2500 rpm for 3 min to mix and stir evenly, and then cooled to room temperature;

[0076] In step (2), 50 g of m-phenylenediamine curing agent was added, and the mixture was stirred at a rotation speed of 2000 rpm for 5 min, and cast to obtain a high thermal conductivity epoxy resin composite material.

[0077] Comparative Example 1

[0078] Comparative Example 1 Compared with Example 4, in the process of preparing the high thermal conductivity epoxy resin composite material in Comparative Example 1, no BNNS was added, and other conditions remained unchanged.

[0079] Comparative Example 2

[0080] Comparative Example 2 Compared with Example 4, in the process of preparing the high thermal conductivity epoxy resin composite material in Comparative Example 2, pristine BN was not added, and other conditions remained unchanged.

[0081] Comparative Example 3

[0082] Comparative Example 3 Compared with Example 4, in the process of preparing the high thermal conductivity epoxy resin composite material in Comparative Example 3, no graphene hybridized boron nitride was added, and other conditions remained unchanged.

[0083] Experimental example

[0084] The properties of the high thermal conductivity epoxy resin composite materials prepared in Examples 4-8 and Comparative Examples 1-3 were tested.

[0085] Thermal conductivity was characterized using a TA Instruments DTC-300 guarded heat flow meter. The samples were made into a circular shape with a diameter of 50 mm and a thickness of 3 mm (according to ASTM E1530). Two samples were made and all different epoxy composites were tested and measured at room temperature. Rheological measurements were performed using a TA Discovery HR 30 hybrid rheometer at room temperature to measure the shear viscosity of epoxy samples filled with pristineBN, BNNS and graphene hybrid boron nitride at a shear rate of 11 / s. Impact resistance was tested using an impact tester. The test results are shown in Table 1:

[0086] Table 1

[0087]

[0088]

[0089] It can be seen from Table 1 that the high thermal conductivity epoxy resin composite materials prepared by the premixing method in Examples 4-8 have good thermal conductivity and impact resistance. From the comparison between Comparative Example 1 and Example 4, it can be seen that in the process of preparing the high thermal conductivity epoxy resin composite materials, the present invention adds hexagonal boron nitride nanosheets, which can significantly improve the thermal conductivity and impact resistance of the high thermal conductivity epoxy resin composite materials. From the comparison between Comparative Example 2 and Example 4, it can be seen that in the process of preparing the high thermal conductivity epoxy resin composite materials, the present invention adds hexagonal boron nitride sheets, which can significantly improve the thermal conductivity and impact resistance of the high thermal conductivity epoxy resin composite materials. From the comparison between Comparative Example 3 and Example 4, it can be seen that in the process of preparing the high thermal conductivity epoxy resin composite materials, the present invention adds graphene hybrid boron nitride, which can significantly improve the thermal conductivity and impact resistance of the high thermal conductivity epoxy resin composite materials.

[0090] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

[0091] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high thermal conductivity epoxy resin composite material, characterized in that: The raw materials of the high thermal conductivity epoxy resin composite material are composed of the following components in parts by weight: 100 parts of epoxy resin, 10-50 parts of hexagonal boron nitride nanosheets (BNNS), 10-50 parts of hexagonal boron nitride sheets (pristine BN), 3-5 parts of graphene hybrid boron nitride, and 20-50 parts of curing agent.

2. The high thermal conductivity epoxy resin composite material according to claim 1, characterized in that: The weight ratio of the BNNS to pristineBN is 1:(0.5-1.5).

3. The high thermal conductivity epoxy resin composite material according to claim 1, characterized in that: The curing agent includes at least one of a meta-phenylenediamine curing agent and a diaminodiphenyl sulfone curing agent.

4. A method for preparing the high thermal conductivity epoxy resin composite material according to any one of claims 1 to 3, comprising the following steps: Step (1) 10-50 parts of BNNS and 10-50 parts of pristine BN, 100 parts of epoxy resin and 3-5 parts of graphene hybrid boron nitride are mixed, stirred at a speed of 2000-2500 rpm for 3-7 minutes, mixed and stirred evenly, and cooled to room temperature: Step (2) adding 20-50 parts of curing agent, stirring at a rotation speed of 2000-2500 rpm for 3-7 minutes, and casting to obtain a high thermal conductivity epoxy resin composite material.

5. The method for preparing a high thermal conductivity epoxy resin composite material according to claim 4, characterized in that: The mixing method of step (1) includes at least one of a premixing method, a masterbatch method, and a solvent-assisted dispersion method.

6. The method for preparing a high thermal conductivity epoxy resin composite material according to claim 5, characterized in that: The premixing method comprises premixing BNNS and pristine BN at a speed of 2000-2500 rpm for 3-7 minutes to allow the powders to fully contact in a dry state, and then adding epoxy resin and graphene hybrid boron nitride to mix and stir evenly; the masterbatch method comprises preparing masterbatches of BNNS-epoxy resin and pristine BN-epoxy resin respectively, and then mixing and stirring the two masterbatches and graphene hybrid boron nitride evenly; the solvent-assisted dispersion method comprises mixing BNNS, pristine BN, graphene hybrid boron nitride and epoxy resin, adding 150 mL of acetone to assist dispersion, and then evaporating the solvent in a vacuum.

7. The method for preparing a high thermal conductivity epoxy resin composite material according to claim 6, characterized in that: The preparation method of the graphene hybrid boron nitride comprises the following steps: A1: Disperse 30-60g of modified graphene oxide and 3-6g of BiCl3 in 10-20L N,N-dimethylformamide, stir magnetically for 0.5-1.5min, and then ultrasonically treat for 15-25min, then slowly add 100-200g of modified boron nitride, stir and ultrasonically treat for 15-25min, and then magnetically stir at room temperature for 7-12h, filter, wash the filter residue with water for 3-5 times, and finally freeze-dry for 36-54h to obtain graphene oxide hybrid boron nitride; A2: Disperse graphene oxide hybrid boron nitride in water to form a 0.1 g / L dispersion, and ultrasonically treat it at 30-50 kHz and 150-250 w for 20-40 min to obtain a graphene oxide hybrid boron nitride solution, then add 50-100 mL of an ascorbic acid aqueous solution containing 0.02-0.04 g of ascorbic acid to 200-400 mL of the graphene oxide hybrid boron nitride solution, and ultrasonically treat it at 30-50 kHz and 150-250 w for 1.5-2.5 h, and then stand at room temperature for 36-54 h to obtain graphene hybrid boron nitride.

8. The method for preparing a high thermal conductivity epoxy resin composite material according to claim 7, characterized in that: The preparation method of the modified boron nitride comprises the following steps: S1: In an ice water bath, add 100-200g BN and 2-4g 3-aminopropyltrimethoxysilane to 30-60kg anhydrous ethanol, ultrasonically disperse for 50-70min, then add 4-8kg water and 10-20kg anhydrous ethanol, condense and reflux at 75-85°C for 10-14h, centrifuge while hot, wash the centrifuged solid with water 7-9 times, and freeze-dry for 40-56h to obtain amino boron nitride; S2: Add 60-90g of amination boron nitride and 60-90g of 3-amino-5-(3-aminophenyl)benzoic acid to 3-4.5L of n-methylpyrrolidone solution and stir for 30-60min, then add 0.2-0.3L of catalyst pyridine and 0.6-0.9mL of stabilizer triphenyl phosphate, and then add 20-30g of LiCl, react at 95-105°C in a N2 nitrogen atmosphere for 10-14h, centrifuge while hot, wash the centrifuged solid with n-methylpyrrolidone solution for 3-5 times, and then freeze-dry for 36-54h to obtain modified boron nitride.

9. The method for preparing a high thermal conductivity epoxy resin composite material according to claim 7, characterized in that: The preparation method of the modified graphene oxide comprises the following steps: P1: 53-106 g of 2-bromo-3-dodecylthiophene and 46-92 g of 2,2,6,6-tetramethylpiperidinylmagnesium chloride and lithium chloride are added to 2-4 L of tetrahydrofuran, and stirred at 25° C. for 2-4 h, and then 2-4 L of tetrahydrofuran and 1-2 g of bis(triphenylphosphine)nickel chloride are added in sequence, and then the stirring is continued at 25° C. for 0.5-1.5 h, and 0.1 mol / L, 1-2 L of hydrochloric acid aqueous solution and 1-2 L of methanol are added, and the filter residue is washed with n-hexane for 3-5 times, and dried under reduced pressure to obtain a modified monomer; P2: Add 50-100 g of graphene oxide to 100-200 L of chloroform, ultrasonically treat at 25°C for 0.5-1.5 h, then add 100-200 L of chloroform solution containing 50-100 g of modified monomer, ultrasonically treat at 25°C for 1-3 h, and then evaporate chloroform at 25°C for 2-4 days to obtain modified graphene oxide.

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