Preparation method and application of modified boron nitride

Abstract

The invention provides a preparation method and application of modified boron nitride, and the preparation method comprises the following steps: carrying out plasma ball milling on a mixture comprising hexagonal boron nitride and a silane coupling agent solution to obtain the modified boron nitride. The preparation method is simple in process, hexagonal boron nitride can be modified in one step, the problem that the surface activation condition of boron nitride is harsh is effectively solved, and the obtained modified boron nitride is more excellent in heat-conducting property and has high compatibility with a polymer matrix.

Description

Technical Field

[0001] This application relates to the field of materials, and more particularly to a method for preparing modified boron nitride and its application. Background Technology

[0002] With the rapid development of electronic information technology, high-frequency applications such as 5G / 6G place higher demands on the dielectric and heat dissipation properties of thermally conductive materials. Boron nitride's high thermal conductivity, low dielectric properties, and insulating characteristics make it suitable for integration into polymer matrices to obtain thermally conductive composites with excellent heat dissipation performance. However, the poor compatibility between boron nitride and the polymer matrix leads to defects within the composite material. Therefore, when using boron nitride, surface modification is usually necessary to graft or coat it with groups or substances more compatible with the polymer matrix, thereby enhancing the interaction between boron nitride and the polymer matrix.

[0003] However, boron nitride itself lacks polar groups such as hydroxyl groups and has good chemical inertness. To address the lack of hydroxyl groups on the boron nitride surface, existing technologies typically employ a method of reacting boron nitride with a strong base to first imbue its surface with hydroxyl groups, followed by a reaction with a coupling agent to modify the surface of boron nitride. However, the use of strong bases can damage the crystal structure at the edges of boron nitride, leading to increased phonon scattering, reduced thermal conductivity, and difficulty in meeting current environmental protection requirements. It also places higher demands on the corrosion resistance of production equipment. Summary of the Invention

[0004] This application provides a method for preparing modified boron nitride. Through plasma ball milling, the modification of hexagonal boron nitride can be achieved with high efficiency while maintaining environmental friendliness.

[0005] This application also provides a modified boron nitride, which is obtained by the above preparation method. The modified boron nitride has better surface modification uniformity and superior thermal conductivity.

[0006] This application also provides a thermally conductive composite material comprising the above-mentioned modified boron nitride, thus exhibiting superior thermal conductivity.

[0007] This application also provides an electronic device comprising the above-described modified boron nitride or the above-described thermally conductive composite material, thus having better heat dissipation performance.

[0008] This application provides a method for preparing modified boron nitride, comprising the following steps:

[0009] Modified boron nitride was obtained by plasma ball milling a mixture including hexagonal boron nitride and a silane coupling agent solution.

[0010] In the preparation method described above, the plasma gas in the plasma ball mill is a neutral gas; and / or, in the plasma ball mill, the applied electric field of the plasma gas is 5~20kV and the current is 0.6~2A; and / or, in the plasma ball mill, the pressure of the plasma gas is 0.4-0.6MPa.

[0011] In the preparation method described above, the plasma ball milling process includes zirconia balls, and the mass ratio of the zirconia balls to hexagonal boron nitride is 10~20:1; and / or, in the plasma ball milling process, the mass ratio of 3mm diameter ball milling balls, 5mm diameter ball milling balls, and 10mm diameter ball milling balls is 12.5~25:12.5~25:25~50; and / or, in the plasma ball milling process, the milling speed is 500~1500 rpm, and the time is 6~12h.

[0012] In the preparation method described above, the silane coupling agent in the silane coupling agent solution includes at least one of KH550, KH560, KH570, dodecyltrimethoxysilane, and hexadecyltrimethoxysilane; and / or, the average particle size of the hexagonal boron nitride is 15~40 μm; and / or, the mass ratio of the hexagonal boron nitride to the silane coupling agent in the silane coupling agent solution is 101~1050:1~5.

[0013] The preparation method described above involves obtaining the silane coupling agent solution by means of the following process: mixing the silane coupling agent with a solvent, wherein the mixing speed is 300~1500 rpm and the time is 0.5~2 h, and the mass ratio of the silane coupling agent to the solvent is (1~5):100.

[0014] This application also provides a modified boron nitride, obtained according to any of the preparation methods described above.

[0015] This application also provides a thermally conductive composite material comprising the aforementioned modified boron nitride.

[0016] The thermally conductive composite material described above is obtained by a preparation method comprising the following processes:

[0017] The modified boron nitride was mixed with a polymer matrix and then heated and cured to obtain a thermally conductive composite material.

[0018] The thermally conductive composite material as described above, wherein the polymer matrix includes at least one of acrylic resin, polyurethane, epoxy resin, and silicone resin; and / or, the mass ratio of the modified boron nitride to the polymer matrix is ​​1 to 3:1.

[0019] This application also provides an electronic device comprising the modified boron nitride described above, or the thermally conductive composite material described in any of the preceding claims.

[0020] The modified boron nitride preparation method provided in this application adopts a plasma ball milling process, which is simple and easy to operate. It can achieve surface modification of hexagonal boron nitride in one step, and is more environmentally friendly and more suitable for industrial production. The modified boron nitride prepared has a uniform surface modification distribution, better thermal conductivity, and a wider range of applications. Attached Figure Description

[0021] Figure 1 This is a comparison of the microstructure and thickness of hexagonal boron nitride before and after ball milling in Example 2 of this application. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0023] Current methods for modifying boron nitride typically involve introducing hydroxyl groups onto the surface of hexagonal boron nitride using a strong base, followed by a reaction with a coupling agent. However, strong bases can disrupt the crystal structure at the edges of boron nitride, leading to decreased thermal conductivity in the modified boron nitride. Furthermore, the use of strong bases raises environmental and safety concerns.

[0024] Based on this, this application provides a method for preparing modified boron nitride, comprising the following steps:

[0025] Modified boron nitride was obtained by plasma ball milling a mixture including hexagonal boron nitride and a silane coupling agent solution.

[0026] The inventors analyzed the principle of plasma ball milling and believed that ball milling can strip multilayer hexagonal boron nitride into fewer layers or even a single layer of hexagonal boron nitride. Therefore, the aspect ratio of the ball-milled hexagonal boron nitride is larger, and increasing the aspect ratio of hexagonal boron nitride can enhance its thermal conductivity.

[0027] On the other hand, plasma discharge can activate the functional groups on the surface of hexagonal boron nitride, increase the grafting amount of silane coupling agent and hexagonal boron nitride, and make the surface modification of modified boron nitride more uniform, thereby achieving a better surface modification effect and improving the compatibility between modified boron nitride and polymer matrix.

[0028] The inventors have organically combined ball milling with plasma discharge and, through extensive experimental verification, applied the plasma ball milling process to the surface modification of hexagonal boron nitride. This process is simple and efficient, and can complete the surface modification of hexagonal boron nitride in one step, giving it higher compatibility with the polymer matrix and higher thermal conductivity. It can be used to prepare thermally conductive composite materials with higher thermal conductivity requirements.

[0029] It is easy to understand that the silane coupling agent solution includes a solvent. This application does not limit the specific chemical composition of the solvent. It can be a common solvent used in the art to disperse silane coupling agents, such as ethanol, or a combination of ethanol and water.

[0030] In a specific embodiment of this application, after plasma ball milling, a drying process can be performed to separate the modified boron nitride from the solvent, resulting in dried modified boron nitride. This application does not limit the drying method; for example, it can be dried in a forced-air oven at 80-100°C for 12-18 hours.

[0031] In a specific embodiment of this application, the plasma gas used in the plasma ball milling is a neutral gas.

[0032] In detail, neutral gases can increase plasma stability and reduce unnecessary side reactions, which can further improve the stability of the modification process.

[0033] This application does not limit the specific composition of the neutral gas, for example, it may be at least one of nitrogen, oxygen and hydrogen.

[0034] Furthermore, when the applied electric field of the plasma gas is 5~20kV and the current is 0.6~2A, the plasma excitation effect on the gas is better, the modification distribution on the surface of hexagonal boron nitride is more uniform, and the modified hexagonal boron nitride has better compatibility with the polymer matrix.

[0035] Furthermore, when the pressure of the plasma gas is 0.4-0.6 MPa, the functional groups on the surface of hexagonal boron nitride can be further activated, which is beneficial to further improving the modification efficiency of hexagonal boron nitride.

[0036] In a specific embodiment of this application, in plasma ball milling, the milling beads include zirconia balls, and the mass ratio of zirconia balls to hexagonal boron nitride is 10~20:1.

[0037] Specifically, by controlling the mass ratio of zirconia balls to hexagonal boron nitride to be 10~20:1, the number of collisions between zirconia balls can be increased, thereby further enhancing the stripping and dispersion effect on hexagonal boron nitride.

[0038] Furthermore, when the mass ratio of 3mm, 5mm and 10mm grinding beads is 12.5~25:12.5~25:25~50, the grinding of hexagonal boron nitride is more thorough, resulting in hexagonal boron nitride with a more uniform aspect ratio distribution.

[0039] Furthermore, when the ball milling speed is 500~1500 rpm and the time is 6~12 h, the thermal conductivity of the modified boron nitride obtained is even better.

[0040] In specific embodiments of this application, the silane coupling agent in the silane coupling agent solution includes at least one of KH550, KH560, KH570, dodecyltrimethoxysilane, and hexadecyltrimethoxysilane.

[0041] In detail, after the coupling agent reacts with boron nitride, the silane coupling agent is grafted onto the surface of hexagonal boron nitride, resulting in modified hexagonal boron nitride with higher compatibility with the polymer matrix.

[0042] Furthermore, when the average particle size of hexagonal boron nitride is 15~40 μm, the obtained modified hexagonal boron nitride exhibits better thermal conductivity.

[0043] In detail, hexagonal boron nitride powder is prone to particle agglomeration due to interlayer van der Waals forces and high surface energy, leading to reduced dispersibility and affecting the interfacial thermal resistance with the polymer matrix, thus resulting in low thermal conductivity of boron nitride thermally conductive composites. When the average particle size of hexagonal boron nitride is within the above-mentioned range, effective dispersion of boron nitride agglomerates can be achieved, promoting the reaction between the silane coupling agent and the surface groups of boron nitride, and further enhancing the modification effect of hexagonal boron nitride.

[0044] Furthermore, in order to further improve the modification effect of hexagonal boron nitride, the mass ratio of hexagonal boron nitride to silane coupling agent in the silane coupling agent solution is 101~1050:1~5.

[0045] In a specific embodiment of this application, the silane coupling agent solution is prepared by a method including the following process: mixing the silane coupling agent with a solvent, wherein the mixing speed is 300~1500 rpm and the time is 0.5~2h, and the mass ratio of the silane coupling agent to the solvent is (1~5):100.

[0046] In detail, mixing the silane coupling agent and the solvent in the above manner can ensure that the silane coupling agent is fully dispersed in the solvent, which can further enhance the modification effect of the silane coupling agent on hexagonal boron nitride. In specific implementation, a high-speed disperser can be used for mixing.

[0047] This application also provides a modified boron nitride, obtained according to the aforementioned preparation method. This modified boron nitride has better compatibility with the polymer matrix and can be used to prepare thermally conductive composite materials with higher heat dissipation requirements.

[0048] This application also provides a thermally conductive composite material, including the aforementioned modified boron nitride, which has higher thermal conductivity and a wider range of applications.

[0049] In a specific embodiment of this application, the thermally conductive composite material is obtained by a preparation method comprising the following processes:

[0050] Modified boron nitride was mixed with a polymer matrix and then heated and cured to obtain a thermally conductive composite material.

[0051] This application does not limit the mixing method of modified boron nitride and polymer matrix. In one specific embodiment, for example, it can be mixed in two stages using a vacuum planetary homogenizer. In the first stage, the revolution is 800-1200 rpm and the rotation is 320-540 rpm, and the mixing time is 1-3 min without vacuum. In the second stage, the revolution is 1200-1500 rpm and the rotation is 560-840 rpm, and the mixing time is 2-4 min with a vacuum degree of -0.08 MPa. After the mixing is completed, the bottom and walls of the mixture are scraped, and the mixing process is repeated. The mixture is mixed a total of three times to obtain the thermally conductive composite material precursor.

[0052] This application does not limit the method of heat curing. In one specific embodiment, for example, the thermally conductive composite material precursor can be placed between two fluorine release films and hot-pressed using a flat vulcanizing apparatus to obtain the thermally conductive composite material.

[0053] In specific embodiments of this application, the polymer matrix includes at least one of acrylic resin, polyurethane, epoxy resin, and silicone resin.

[0054] In detail, the modified boron nitride has better compatibility with the aforementioned polymer matrix.

[0055] Furthermore, when the mass ratio of modified boron nitride to polymer matrix is ​​1~3:1, the modified boron nitride is better dispersed in the polymer matrix, and the thermal conductivity of the resulting thermally conductive composite material is further improved.

[0056] This application also provides an electronic device, including the aforementioned modified boron nitride or the aforementioned thermally conductive composite material. This electronic device can be any structural component in the electronics field that requires heat dissipation. Specifically, the electronic device can, for example, consist of a thermally conductive composite material substrate and a memory chip disposed on the thermally conductive composite material substrate. This electronic device has better stability and can achieve efficient heat dissipation.

[0057] Example 1

[0058] The preparation method of the thermally conductive composite material in this embodiment includes the following steps:

[0059] 1) Hexadecyltrimethoxysilane and anhydrous ethanol were mixed evenly using a high-speed disperser to obtain a silane coupling agent solution, wherein the mass ratio of hexadecyltrimethoxysilane to anhydrous ethanol was 1:99, the disperser speed was 600 rpm, and the mixing time was 30 min;

[0060] 2) The silane coupling agent solution, hexagonal boron nitride and zirconia balls with an average particle size of 20 μm were added to a ball mill jar for plasma ball milling to obtain modified boron nitride wet material. The mass ratio of hexagonal boron nitride, silane coupling agent solution and zirconia balls was 1:1:10, and the mass ratio of zirconia balls with particle sizes of 3 mm, 5 mm and 10 mm was 1:1:2. The ball milling speed was set to 600 rpm, the ball milling time was 8 h, the plasma gas was nitrogen, the plasma gas pressure was 0.5 MPa, the external electric field of the plasma gas was 10 kV and the current was 1.0 A.

[0061] 3) The modified boron nitride wet material was dried in a forced-air drying oven at 80℃ for 12 hours to obtain dried modified boron nitride;

[0062] 4) Modified boron nitride and two-component silicone resin (SYLGRAD 184) were mixed in two stages using a vacuum planetary homogenizer at a mass ratio of 3:2. The first stage of mixing involved a revolution of 800 rpm and a rotation of 320 rpm for 1 minute without vacuum. The second stage involved a revolution of 1200 rpm and a rotation of 560 rpm for 2 minutes with a vacuum of -0.08 MPa. After mixing, the bottom and sides of the mixture were scraped, and the mixing process was repeated three times to obtain the thermally conductive composite material precursor.

[0063] 5) Place the thermally conductive composite material precursor between two fluorine release films and hot press it using a flat vulcanizing apparatus to obtain the thermally conductive composite material.

[0064] Example 2

[0065] The preparation method of the thermally conductive composite material in this embodiment includes the following steps:

[0066] 1) Hexadecyltrimethoxysilane and anhydrous ethanol were mixed evenly using a high-speed disperser to obtain a silane coupling agent solution, wherein the mass ratio of hexadecyltrimethoxysilane to anhydrous ethanol was 5:100, the disperser speed was 1000 rpm, and the mixing time was 60 min;

[0067] 2) The silane coupling agent solution, hexagonal boron nitride and zirconia balls with an average particle size of 30 μm were added to a ball mill jar for plasma ball milling to obtain modified boron nitride wet material. The mass ratio of hexagonal boron nitride, silane coupling agent solution and zirconia balls was 4:3:60, and the mass ratio of zirconia balls with particle sizes of 3 mm, 5 mm and 10 mm was 1:2:2. The ball milling speed was set to 900 rpm, the ball milling time was 10 h, the plasma gas was nitrogen, the plasma gas pressure was 0.6 MPa, the external electric field of the plasma gas was 15 kV and the current was 1.5 A.

[0068] 3) The modified boron nitride wet material was dried in a forced-air drying oven at 80℃ for 12 hours to obtain dried modified boron nitride;

[0069] 4) Modified boron nitride and two-component silicone resin (SYLGRAD 184) were mixed in two stages using a vacuum planetary homogenizer at a mass ratio of 3:2. The first stage of mixing involved a revolution of 800 rpm and a rotation of 320 rpm for 1 minute without vacuum. The second stage involved a revolution of 1200 rpm and a rotation of 560 rpm for 2 minutes with a vacuum of -0.08 MPa. After mixing, the bottom and sides of the mixture were scraped, and the mixing process was repeated three times to obtain the thermally conductive composite material precursor.

[0070] 5) Place the thermally conductive composite material precursor between two fluorine release films and hot press it using a flat vulcanizing apparatus to obtain the thermally conductive composite material.

[0071] Example 3

[0072] The preparation method of the thermally conductive composite material in this embodiment is basically the same as that in Example 1, except that the external electric field of the plasma gas is 5kV and the current is 0.6A.

[0073] Example 4

[0074] The preparation method of the thermally conductive composite material in this embodiment is basically the same as that in Example 1, except that the mass ratio of zirconia spheres to hexagonal boron nitride is 20:1.

[0075] Example 5

[0076] The preparation method of the thermally conductive composite material in this embodiment is basically the same as that in Example 1, except that the mass ratio of zirconia spheres with particle sizes of 3mm, 5mm and 10mm is 1:2:4.

[0077] Example 6

[0078] The preparation method of the thermally conductive composite material in this embodiment is basically the same as that in Example 1, except that the external electric field of the plasma gas is 3kV and the current is 0.3A.

[0079] Example 7

[0080] The preparation method of the thermally conductive composite material in this embodiment is basically the same as that in Example 1, except that the mass ratio of zirconia spheres to hexagonal boron nitride is 5:1.

[0081] Example 8

[0082] The preparation method of this comparative thermally conductive composite material is basically the same as that of Example 1, except that the mass ratio of zirconia spheres with particle sizes of 10 mm, 15 mm and 20 mm is 1:1:2.

[0083] Comparative Example 1

[0084] The preparation method of this comparative thermally conductive composite material is basically the same as that of Example 1, except that plasma gas assistance is not used.

[0085] Comparative Example 2

[0086] The preparation method of this comparative thermally conductive composite material is basically the same as that of Example 2, except that a silane coupling agent is not used.

[0087] Experimental Example 1

[0088] 1. The thermal conductivity of the thermally conductive composite materials in all examples and comparative examples was measured, and the results are shown in Table 1. Measurement method: A thermal conductivity meter of type DRL-III from Xiangtan Instruments was used, referring to the ATSM D5470 heat flow method, with a pressure of 30N.

[0089] 2. The viscosity of the dried modified boron nitride mixtures prepared in all examples and comparative examples was measured, and the results are shown in Table 1. Measurement method: The dried modified boron nitride was mixed with vinyl silicone oil (50 mPa·s viscosity) at a mass ratio of 3:7 using a vacuum planetary homogenizer in two stages. The first stage of mixing involved a revolution of 800 rpm and a rotation of 320 rpm for 1 min without vacuum. The second stage involved a revolution of 1200 rpm and a rotation of 560 rpm for 2 min under a vacuum of -0.08 MPa. After mixing, the mixture was cooled to 25°C, and the viscosity was measured using an NJD-8S viscometer, which is the viscosity of the modified boron nitride mixture.

[0090] 3. The thickness of the hexagonal boron nitride lamellars in Example 2 before and after ball milling was measured. The results are shown in [the table below]. Figure 1 .

[0091] The thickness of the hexagonal boron nitride sheets was measured using atomic force microscopy (AFM).

[0092] Figure 1The images show a comparison of the microstructure and thickness of hexagonal boron nitride before and after ball milling in Example 2 of this application. (a) shows the microstructure of hexagonal boron nitride before ball milling; (b) shows the thickness measurement of hexagonal boron nitride before ball milling; (c) shows the microstructure of hexagonal boron nitride after ball milling; and (d) shows the thickness measurement of hexagonal boron nitride after ball milling.

[0093] Depend on Figure 1 It can be seen that the thickness of hexagonal boron nitride is significantly reduced after ball milling, indicating that the ball-milled hexagonal boron nitride has better thermal conductivity.

[0094] Table 1

[0095]

[0096] Analysis of Table 1 leads to the following conclusions:

[0097] 1) Comparing Examples 1, 3, 7 and Comparative Example 1, it can be seen that the thermally conductive composite material prepared by modified boron nitride obtained by plasma gas-assisted ball milling has higher thermal conductivity and lower viscosity of the modified boron nitride mixed oil, indicating that plasma gas is crucial in the ball milling process.

[0098] 2) Comparing Examples 1 and 7, it can be seen that when the applied electric field of the plasma gas is 5~20kV and the current is 0.6~2A, the modified boron nitride obtained by plasma ball milling has a better modification effect.

[0099] 3) Comparing Example 2 and Comparative Example 2, it can be seen that the thermally conductive composite material prepared by adding silane coupling agent to modify hexagonal boron nitride has higher thermal conductivity and lower viscosity of the mixed oil of modified boron nitride, indicating that the hexagonal boron nitride modified by silane coupling agent has better compatibility with the polymer matrix, and silane coupling agent is very important.

[0100] 4) Comparing Example 1 and Example 6, it can be seen that hexagonal boron nitride with an average particle size of 15~40 μm helps to further enhance the modification effect of hexagonal boron nitride.

[0101] 5) Comparing Example 1 and Example 8, it can be seen that when the mass ratio of zirconia balls to hexagonal boron nitride is 10~20:1, the modification effect on hexagonal boron nitride is further improved.

[0102] 6) Comparing Example 1 and Example 9, it can be seen that when the mass ratio of 3mm diameter grinding beads, 5mm diameter grinding beads and 10mm diameter grinding beads is 12.5~25:12.5~25:25~50, the modification effect on hexagonal boron nitride is further improved.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing modified boron nitride, characterized in that, Includes the following steps: Modified boron nitride was obtained by plasma ball milling a mixture including hexagonal boron nitride and a silane coupling agent solution.

2. The preparation method according to claim 1, characterized in that, In the plasma ball milling process, the plasma gas is a neutral gas; and / or, In the plasma ball milling process, the applied electric field of the plasma gas is 5~20kV, and the current is 0.6~2A; and / or, In the plasma ball milling process, the pressure of the plasma gas is 0.4-0.6 MPa.

3. The preparation method according to claim 1 or 2, characterized in that, In the plasma ball milling process, the milling beads include zirconia balls, and the mass ratio of the zirconia balls to hexagonal boron nitride is 10~20:1; and / or, In the plasma ball milling process, the mass ratio of 3mm, 5mm, and 10mm grinding beads is 12.5~25:12.5~25:25~50; and / or, In the plasma ball milling process, the milling speed is 500~1500 rpm and the time is 6~12 hours.

4. The preparation method according to any one of claims 1-3, characterized in that, The silane coupling agent in the silane coupling agent solution includes at least one selected from KH550, KH560, KH570, dodecyltrimethoxysilane, and hexadecyltrimethoxysilane; and / or, The hexagonal boron nitride has an average particle size of 15~40 μm; and / or, The mass ratio of silane coupling agent in the hexagonal boron nitride and silane coupling agent solution is 101~1050:1~5.

5. The preparation method according to any one of claims 1-4, characterized in that, The silane coupling agent solution is prepared by a method including the following process: mixing the silane coupling agent with a solvent, wherein the mixing speed is 300~1500 rpm and the time is 0.5~2h, and the mass ratio of the silane coupling agent to the solvent is (1~5):

100.

6. A modified boron nitride, characterized in that, It is obtained according to the preparation method according to any one of claims 1-5.

7. A thermally conductive composite material, characterized in that, Includes the modified boron nitride as described in claim 6.

8. The thermally conductive composite material according to claim 7, characterized in that, The thermally conductive composite material is obtained by a preparation method including the following processes: The modified boron nitride was mixed with a polymer matrix and then heated and cured to obtain a thermally conductive composite material.

9. The thermally conductive composite material according to claim 8, characterized in that, The polymer matrix includes at least one selected from acrylic resin, polyurethane, epoxy resin, and silicone resin; and / or, The mass ratio of the modified boron nitride to the polymer matrix is ​​1~3:

1.

10. An electronic device, characterized in that, This includes the modified boron nitride as described in claim 6, or the thermally conductive composite material as described in any one of claims 7-9.

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