A three-dimensional graphene thermal conductive and wave-absorbing material and its preparation method

Abstract

The present invention belongs to the technical field of interface materials, and relates to a three-dimensional graphene thermal conductive and wave-absorbing material and a preparation method thereof, which includes the following steps: Step 1: Preparation of thermal conductive and wave-absorbing fillers; Step 2: Mixing PDMS / three-dimensional graphene, PDMS / three-dimensional graphene composite material, and graphene composite material II as thermal conductive and wave-absorbing fillers with vinyl silicone oil, hydrogen-containing silicone oil, catalyst, and inhibitor by a mixer to obtain a mixed solution; Step 3: Pressing the mixed solution in Step 2 into a sheet by a calender and then curing it to obtain a thermal conductive and wave-absorbing gasket. The present invention utilizes the network skeleton structure of three-dimensional graphene to exert its high thermal conductivity and impedance matching functions, and the obtained three-dimensional graphene thermal conductive and wave-absorbing material has high thermal conductivity, broadband wave absorption, and high resilience.

Description

Technical Field

[0001] The present invention belongs to the technical field of interface materials, and particularly relates to a three-dimensional graphene heat-conducting and wave-absorbing material and a preparation method thereof. Background Art

[0002] With the development of integration technology and the increasing densification of microelectronic assembly, the heat dissipation and electromagnetic noise interference of electronic devices have become more and more obvious. The heat-conducting and insulating gasket can not only achieve insulation, but also play a role in heat conduction and wave absorption, which is a commonly used method at present.

[0003] Conventional heat-conducting and wave-absorbing materials are composed of silicone resin and heat-conducting fillers such as alumina, aluminum nitride, boron nitride, and wave-absorbing materials such as carbonyl iron and ferrite. Due to the limitation of the total filling amount, the improvement of heat-conducting performance will inevitably lead to the decline of wave-absorbing performance. In addition, in order to obtain higher heat-conducting and wave-absorbing performance, a large amount of fillers must be added, which will cause the loss of compressibility and resilience. And the gasket having a certain resilience is the premise to ensure its effective use. The loss of resilience will reduce the service life of the gasket and cause a significant decline in performance.

[0004] An ideal thermal interface material should have high thermal conductivity and resilience. The methods to achieve resilience include using an elastic skeleton and elastic fillers, while the skeletons and fillers with good elastic effects will all lead to the decline of thermal conductivity. Graphene has high thermal conductivity and electrical conductivity, and is an ideal heat-conducting and wave-absorbing material. At the same time, the three-dimensional network structure of graphene can also be used as an elastic skeleton. The patents for preparing heat-conducting materials using graphene include CN201910026181.8 and CN201410756830.7. Among them, patent CN201910026181.8 discloses a three-dimensional graphene / elastomer thermal interface material and a preparation method thereof, which obtains the thermal interface material by coating a polymer material on the surface of three-dimensional graphene and then removing it, but there is no description of the influence of three-dimensional graphene on the wave-absorbing effect, and the thermal conductivity of the obtained interface material is low. Patent CN201410756830.7 discloses a preparation method of a foam graphene thermal interface material with high thermal conductivity. Although the thermal conductivity is relatively high, the surface viscosity and mechanical strength are poor, and it cannot effectively solve the heat transfer problem as a thermal interface material. Therefore, in order to meet the actual application requirements, it is particularly important to develop a thermal interface material that combines heat conduction and wave absorption, and at the same time has high elasticity and mechanical properties. Summary of the Invention

[0005] The present invention aims at the deficiencies of the above-mentioned existing technologies and provides a three-dimensional graphene heat-conducting and wave-absorbing material and a preparation method thereof.

[0006] The specific technical solution of the present invention is as follows:

[0007] The first object of the present invention is to provide a preparation method of a three-dimensional graphene thermal conductive and wave-absorbing material, comprising the following steps:

[0008] Step 1: Preparation of thermal conductive and wave-absorbing fillers

[0009] A. Subject graphene oxide to solvothermal reaction, and obtain three-dimensional graphene after freeze-drying;

[0010] B. Mix graphene oxide, thermal conductive powder, and polyethylene glycol, subject to solvothermal reaction, and obtain three-dimensional graphene / composite material I after freeze-drying;

[0011] C. Mix three-dimensional graphene and three-dimensional graphene / composite material I with polydimethylsiloxane (PDMS) respectively, and obtain PDMS / three-dimensional graphene and PDMS / three-dimensional graphene composite material after curing;

[0012] D. After crushing and sieving three-dimensional graphene, mix it with thermal conductive powder and additives in a blender, and obtain three-dimensional graphene composite material II after drying;

[0013] Step 2: Mix PDMS / three-dimensional graphene, PDMS / three-dimensional graphene composite material, and graphene composite material II as thermal conductive and wave-absorbing fillers with vinyl silicone oil, hydrogen-containing silicone oil, catalyst, and inhibitor in a blender to obtain a mixed solution;

[0014] Step 3: Press the mixed solution in Step 2 into a sheet by a calender and obtain a thermal conductive and wave-absorbing gasket after baking and curing.

[0015] The present invention utilizes the internal structure of three-dimensional graphene. On the one hand, it provides high thermal conductivity to form a thermal conductive network. On the other hand, it optimizes impedance matching to form broadband wave absorption with other wave-absorbing powders. Secondly, there are a large number of cavity / wall interfaces in the three-dimensional system, which can increase the multiple reflections of incident electromagnetic waves and is conducive to the absorption of electromagnetic waves. In addition, the three-dimensional network structure of three-dimensional graphene is an ideal elastic backbone matrix and backbone filler, providing space for realizing high elasticity.

[0016] Further, in Step A, the preparation method of the three-dimensional graphene: Add a reducing agent to the graphene oxide solution, fully dissolve it by ultrasonic wave, react in a reaction kettle at 100°C - 200°C for 15 min - 6 h to obtain a mixed colloidal solution, and dry the mixed colloidal solution in a freeze dryer for 48 h to obtain three-dimensional graphene.

[0017] Further, the graphene oxide is prepared by the improved Hummers method, and the concentration of graphene oxide in the graphene oxide solution is 40 - 120 mg / ml; the reducing agent is one or a combination of two or more of vitamin C, ascorbic acid, ethylenediamine, and pyrrole, and the mass ratio of the reducing agent to graphene oxide is (0.5 - 5):1, preferably (1 - 3):1.

[0018] Further, in the first step, the preparation methods of the PDMS / three-dimensional graphene and the PDMS / three-dimensional graphene composite material are as follows: Put the three-dimensional graphene and the graphene composite material into PDMS respectively to make them completely immersed, and then place them in an oven to evacuate for 15 minutes to obtain the PDMS / three-dimensional graphene material and the PDMS / three-dimensional graphene composite material.

[0019] Further, the wave-absorbing powder is also included in the step B, and the mass ratio of graphene: wave-absorbing powder: heat-conducting powder in the obtained three-dimensional graphene / composite material I is (1-10):(0-2):1.

[0020] Further, polyvinylpyrrolidone (PVP) is also included in the step B.

[0021] Further, in the step D, the size of the three-dimensional graphene after crushing and sieving is 0.5-50 μm.

[0022] Further, the wave-absorbing powder is also included in the step D. The heat-conducting powder and the wave-absorbing powder form a heat-conducting and wave-absorbing composite powder. The mass proportion of the heat-conducting powder in the heat-conducting and wave-absorbing composite powder is 20-100%, and the mass proportion of the wave-absorbing powder is 0-80%; the proportion of the three-dimensional graphene in the total mass is 1-5 wt%.

[0023] Further, in the first step, the heat-conducting powder is one or more of alumina, aluminum nitride, zinc oxide, boron nitride, silicon nitride, silicon carbide, aluminum hydroxide, and the particle size of the heat-conducting powder is preferably 0.2 μm-120 μm.

[0024] Preferably, the heat-conducting powder is boron nitride, silicon nitride, silicon carbide, aluminum nitride. The selection principle is materials with both wave-absorbing effect and heat-conducting effect to achieve the function of heat-conducting and wave-absorbing simultaneously and reduce the overall filler content.

[0025] Further, the wave-absorbing powder is one or more of carbonyl iron powder, iron-nickel alloy, iron-silicon alloy, iron-aluminum alloy, ferrite, carbon black, carbon nanotube, iron fiber, and the particle size of the wave-absorbing powder is preferably 0.1-40 μm.

[0026] Further, the vinyl content of the vinyl silicone oil is 0.5-0.6 wt%, and the viscosity is 50-10000 mPa·s; the hydrogen content of the hydrogen-containing silicone oil is 0.1%-0.6%, and the viscosity is 50-1000 mPa·s.

[0027] Further, the inhibitor is ethynylcyclohexanol, and the mass proportion in the total mass is 0.01-0.5%; the catalyst is a platinum catalyst, and the mass proportion in the total mass is 0.01-1%.

[0028] Further, the auxiliary agent is one or more of silane coupling agent, phthalate coupling agent or absolute ethanol, and the proportion of the auxiliary agent in the total mass is 0.1-3wt%.

[0029] Further, in the step D, the rotation speed of the mixer is 100-400r / min, and the stirring time is 1-6min.

[0030] Further, in the second step, the rotation speed of the mixer is 400-1500r / min, and the stirring time is 5-12min.

[0031] Further, in the third step, the curing temperature is 60-150°C, and the time is 20-60min.

[0032] The second object of the present invention is to provide a three-dimensional graphene thermal conductive and wave-absorbing material prepared by the preparation method of the three-dimensional graphene thermal conductive and wave-absorbing material as described above.

[0033] The beneficial effects of the present invention are as follows:

[0034] (1) Three-dimensional graphene has a three-dimensional network structure, which can not only serve as the skeleton of the wave-absorbing agent without being limited by the addition amount, but also fill the thermal conductive powder and wave-absorbing powder in the skeleton to construct a three-dimensional graphene thermal conductive and wave-absorbing composite material, forming a thermal conductive and wave-absorbing network, taking into account both thermal conductivity and wave-absorbing performance;

[0035] (2) Its unique three-dimensional structure provides the best design for impedance matching, which can not only ensure the wave-absorbing performance at a low filling amount, but also realize effective matching from low frequency to high frequency and achieve broadband wave absorption by adjusting the pore structure, size and quantity;

[0036] (3) Graphene has high thermal conductivity. By compounding graphene with thermal conductive powder and utilizing the high thermal conductivity and interconnected structure of graphene, the thermal conductivity can be effectively improved;

[0037] (4) The network structure of three-dimensional graphene is an ideal high-elastic matrix. After being effectively combined with thermal conductive powder and wave-absorbing powder, it endows the material with high thermal conductivity and ensures the compressibility and resilience of the composite material. Specific Embodiments

[0038] The principles and features of the present invention will be described below in conjunction with examples. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0039] Example 1

[0040] (1) First, weigh 120 ml of graphene oxide at 50 mg / ml. After ultrasonic dispersion for 10 min, add vitamin C. The mass of vitamin C is 3 times that of graphene oxide. After sufficient ultrasonic mixing, react at 120 °C in an autoclave for 4 h. Place the resulting colloidal solution after the reaction in a freeze dryer and dry for 48 h to obtain three-dimensional graphene.

[0041] (2) Weigh 380 ml of graphene oxide at 50 mg / ml. After ultrasonic dispersion for 10 min, add 0.8 g of polyethylene glycol - 2000, then add ferrite and aluminum nitride. After sufficient ultrasonic dissolution and mixing, react at 120 °C in an autoclave for 4 h. After the reaction, place the resulting mixture in a freeze dryer and dry for 72 h to obtain three-dimensional graphene / composite material one. Among them, the mass ratio of graphene, ferrite, and AlN in the obtained three-dimensional graphene / composite material one is 7:2:1.

[0042] (3) Immerse 3 g of three-dimensional graphene and 4 g of three-dimensional graphene / composite material one into 0.16 g and 0.21 g of PDMS solution respectively to make them completely submerged. Then place them in an oven and evacuate for 15 min to remove the bubbles in the three-dimensional materials. After cooling to room temperature, obtain PDMS / three-dimensional graphene and PDMS / three-dimensional graphene composite material.

[0043] (4) Crush the three-dimensional graphene through a pulverizer and sieve to obtain three-dimensional graphene with a size of 100 μm. Weigh 5 g of the sieved three-dimensional graphene, 10 g of 50 μm alumina, 15 g of 100 μm aluminum nitride, 1.5 g of coupling agent, and 5 g of auxiliary agent anhydrous ethanol. Stir at 200 r / min with a double planetary mixer for 5 min and then dry at 250 °C for 12 h to obtain graphene composite material two.

[0044] (5) Mix 1 g of PDMS / three-dimensional graphene, 2 g of PDMS / three-dimensional graphene composite material, 10 g of graphene composite material two with 0.5 g of vinyl silicone oil with a vinyl content of 0.5% and a viscosity of 200 mPa·s, 0.5 g of hydrogen-containing silicone oil with a hydrogen content of 0.4% and a viscosity of 300 mPa·s, 0.01 g of platinum catalyst, and 0.01 g of inhibitor ethynylcyclohexanol with a double planetary mixer at 800 r / min for 10 min to obtain a mixed solution. Press the mixed solution with a calender into a sheet with a thickness of 2 mm and bake at 125 °C for 30 min to obtain a high resilience thermal conductive and wave-absorbing gasket.

[0045] Example 2

[0046] (1) First, weigh 120 ml of graphene oxide at 100 mg / ml. After ultrasonic dispersion for 10 min, add vitamin C. The mass of vitamin C is 3 times that of graphene oxide. After ultrasonic dissolution and mixing, react at 180 °C in an autoclave for 4 h. Place the resulting mixed colloidal solution after the reaction in a freeze dryer and dry for 48 h to obtain three-dimensional graphene.

[0047] (2) Weigh 380 ml of graphene oxide at 100 mg / ml. After ultrasonic dispersion for 10 min, add 0.8 g of polyethylene glycol-2000, then add ferrite and boron nitride. After ultrasonic dissolution and mixing, react at 180 °C in an autoclave for 4 h. After the reaction, place the resulting mixed solution in a freeze dryer and dry for 72 h to obtain three-dimensional graphene / composite material one. Among them, the mass ratio of graphene, ferrite, and BN in the obtained three-dimensional graphene / composite material one is 5:2:1.

[0048] (3) Immerse 3 g of three-dimensional graphene and 4 g of graphene composite material into 0.32 g and 0.42 g of PDMS solution respectively to make them completely submerged. Then place them in an oven and evacuate for 15 min to remove the bubbles in the three-dimensional materials. After cooling to room temperature, obtain PDMS / three-dimensional graphene and PDMS / three-dimensional graphene composite material.

[0049] (4) Crush the three-dimensional graphene through a pulverizer and sieve to obtain 100 μm three-dimensional graphene. Weigh 5 g of sieved three-dimensional graphene, 10 g of 50 μm alumina, 15 g of 100 μm aluminum nitride, 20 g of carbonyl iron powder, 5 g of zinc oxide, 1.5 g of coupling agent, and 5 g of absolute ethanol. Stir at 200 r / min with a double planetary mixer for 5 min and then dry at 250 °C for 12 h to obtain graphene composite material two.

[0050] (5) Mix 2 g of PDMS / three-dimensional graphene, 3 g of PDMS / three-dimensional graphene composite material, 15 g of graphene composite material two with 0.3 g of vinyl silicone oil with a vinyl content of 0.5% and a viscosity of 50 mPa·s, 0.2 g of vinyl silicone oil with a vinyl content of 0.6% and a viscosity of 1000 mPa·s, 0.5 g of hydrogen-containing silicone oil with a hydrogen content of 0.5% and a viscosity of 500 mPa·s, 0.01 g of platinum catalyst, and 0.01 g of inhibitor ethynylcyclohexanol with a double planetary mixer at 800 r / min for 10 min to obtain a mixed solution. Press the mixed solution into a sheet with a thickness of 2 mm by a calender and bake at 125 °C for 30 min to obtain a high resilience thermal conductive and wave-absorbing gasket.

[0051] Example 3

[0052] (1) First, weigh 120 ml of graphene oxide at 50 mg / ml. After ultrasonic dispersion for 10 min, add vitamin C. The mass of vitamin C is 3 times that of graphene oxide. After ultrasonic dissolution and mixing, react at 120 °C in an autoclave for 4 h. Place the resulting mixed colloidal solution after the reaction in a freeze dryer and dry for 48 h to obtain three-dimensional graphene.

[0053] (2) Weigh 380 ml of graphene oxide at 50 mg / ml. After ultrasonic dispersion for 10 min, add 0.8 g of polyethylene glycol - 2000, then add alumina and aluminum nitride. After ultrasonic dissolution and mixing, react at 120 °C in an autoclave for 4 h. After the reaction, place the resulting mixed solution in a freeze dryer and dry for 72 h to obtain three-dimensional graphene / composite material I. Among them, the mass ratio of graphene, alumina, and AlN in the obtained three-dimensional graphene / composite material I is 5:2:2.

[0054] (3) Immerse 3 g of three-dimensional graphene and 4 g of graphene composite material into 0.16 g and 0.21 g of PDMS solution respectively to make them completely submerged. Then place them in an oven and evacuate for 15 min to remove the bubbles in the three-dimensional materials. After cooling to room temperature, obtain PDMS / three-dimensional graphene and PDMS / three-dimensional graphene composite material.

[0055] (4) Crush the three-dimensional graphene through a pulverizer and sieve to obtain three-dimensional graphene with a size of 100 μm. Weigh 5 g of sieved three-dimensional graphene, 10 g of 50 μm alumina, 15 g of 100 μm aluminum nitride, 2 g of 10 μm silicon nitride, 15 g of 7 μm carbonyl iron, 1.5 g of coupling agent, and 5 g of absolute ethanol. Stir at 200 r / min for 5 min with a double planetary mixer and then dry at 250 °C for 12 h to obtain graphene composite material II.

[0056] (5) Mix 1 g of PDMS / three-dimensional graphene, 2 g of PDMS / three-dimensional graphene composite material, 10 g of graphene composite material II with 0.5 g of vinyl silicone oil with a vinyl content of 0.5% and a viscosity of 200 mPa·s, 0.5 g of hydrogen-containing silicone oil with a hydrogen content of 0.4% and a viscosity of 300 mPa·s, 0.01 g of platinum catalyst, and 0.01 g of inhibitor ethynylcyclohexanol with a double planetary mixer at 800 r / min for 10 min to obtain a mixed solution. Press the mixed solution into a sheet with a thickness of 2 mm by a calender, and bake at 125 °C for 30 min to obtain a high-elasticity heat-conducting and wave-absorbing gasket.

[0057] Example 4

[0058] (1) First, weigh 120 ml of graphene oxide at 50 mg / ml. After ultrasonic dispersion for 10 min, add vitamin C. The mass of vitamin C is 3 times that of graphene oxide. After ultrasonic dissolution and mixing, react at 120 °C in an autoclave for 4 h. After the reaction, place the obtained mixed colloidal solution in a freeze dryer and dry for 48 h to obtain three-dimensional graphene.

[0059] (2) Weigh 380 ml of graphene oxide at 50 mg / ml. After ultrasonic dispersion for 10 min, add 0.8 g of polyethylene glycol-2000, then add alumina and boron nitride. After ultrasonic dissolution and mixing, react at 120 °C in an autoclave for 4 h. After the reaction, place the obtained mixed solution in a freeze dryer and dry for 72 h to obtain three-dimensional graphene / composite material I. Among them, the mass ratio of graphene, alumina, and boron nitride in the obtained three-dimensional graphene / composite material I is 6:2:1.

[0060] (3) Immerse 3 g of three-dimensional graphene and 4 g of graphene composite material into 0.16 g and 0.21 g of PDMS solution respectively to make them completely submerged. Then place them in an oven and evacuate for 15 min to remove the bubbles in the three-dimensional materials. After cooling to room temperature, obtain PDMS / three-dimensional graphene and PDMS / three-dimensional graphene composite material.

[0061] (4) Crush the three-dimensional graphene through a pulverizer and sieve to obtain 100 μm three-dimensional graphene. Weigh 5 g of sieved three-dimensional graphene, 10 g of 50 μm alumina, 15 g of 100 μm aluminum nitride, 5 g of 4 μm carbonyl iron powder, 1.5 g of coupling agent, and 5 g of absolute ethanol. Stir at 200 r / min with a double planetary mixer for 5 min and then dry at 250 °C for 12 h to obtain graphene composite material II.

[0062] (5) Mix 1 g of PDMS / three-dimensional graphene, 2 g of PDMS / three-dimensional graphene composite material, 10 g of graphene composite material II with 0.5 g of vinyl silicone oil with a vinyl content of 0.5% and a viscosity of 200 mPa·s, 0.5 g of hydrogen-containing silicone oil with a hydrogen content of 0.4% and a viscosity of 300 mPa·s, 0.01 g of platinum catalyst, and 0.01 g of inhibitor ethynylcyclohexanol with a double planetary mixer at 800 r / min for 10 min to obtain a mixed solution. Press the mixed solution into a sheet with a thickness of 2 mm by a calender, and bake at 125 °C for 30 min to obtain a high resilience thermally conductive and wave-absorbing gasket.

[0063] Comparative Example 1

[0064] (1) After pulverizing and sieving three-dimensional graphene with a pulverizer, three-dimensional graphene with a size of 100 μm is obtained. Weigh 5 g of the sieved three-dimensional graphene, 10 g of 50-μm alumina, 15 g of 100-μm aluminum nitride, 1.5 g of coupling agent, and 5 g of absolute ethanol. After stirring at 200 r / min for 5 min with a double planetary mixer, it is dried at 250 °C for 12 h to obtain graphene composite material two.

[0065] (2) Mix 13 g of graphene composite material two with 0.5 g of vinyl silicone oil, 0.5 g of hydrogen-containing silicone oil, 0.01 g of platinum catalyst, and 0.01 g of inhibitor ethynylcyclohexanol with a double planetary mixer at 800 r / min for 10 min to obtain a mixed solution. Press the mixed solution into a sheet with a thickness of 2 mm using a calender, and bake it at 125 °C for 30 min to obtain a high-elasticity thermal conductive and wave-absorbing gasket.

[0066] Comparative Example 2

[0067] (1) First, weigh 120 ml of graphene oxide at 50 mg / ml. After ultrasonic dispersion for 10 min, add vitamin C. The mass of vitamin C is 3 times that of graphene oxide. After ultrasonic dissolution and mixing, react at 120 °C in an autoclave for 4 h. After the reaction, place the obtained mixed colloidal solution in a freeze dryer and dry it for 48 h to obtain three-dimensional graphene.

[0068] (2) Without pretreatment, directly mix 5 g of three-dimensional graphene, 10 g of alumina, 15 g of aluminum nitride, 1.4 g of Fe 3 O 4 with 0.5 g of vinyl silicone oil, 0.5 g of hydrogen-containing silicone oil, 0.01 g of platinum catalyst, and 0.01 g of inhibitor ethynylcyclohexanol with a double planetary mixer at 800 r / min for 10 min to obtain a mixed solution. Press the mixed solution into a sheet with a thickness of 2 mm using a calender, and bake it at 125 °C for 30 min to obtain a high-elasticity thermal conductive and wave-absorbing gasket.

[0069] Comparative Example 3

[0070] Prepare PDMS / three-dimensional graphene according to the method ratio of Example 1. Mix 1 g of PDMS / three-dimensional graphene, 13 g of graphene composite material two with 0.5 g of vinyl silicone oil, 0.5 g of hydrogen-containing silicone oil, 0.01 g of platinum catalyst, and 0.01 g of inhibitor ethynylcyclohexanol with a double planetary mixer at 800 r / min for 10 min to obtain a mixed solution. Press the mixed solution into a sheet with a thickness of 2 mm using a calender, and bake it at 125 °C for 30 min to obtain a high-elasticity thermal conductive and wave-absorbing gasket.

[0071] Comparative Example 4

[0072] (1) Obtain PDMS / three-dimensional graphene and PDMS / three-dimensional graphene composite material according to Example 1.

[0073] (2) The three-dimensional graphene was pulverized and sieved by a pulverizer to obtain 100-μm three-dimensional graphene. 5 g of the sieved three-dimensional graphene, 10 g of 50-μm alumina, 15 g of 100-μm aluminum nitride, and 5 g of absolute ethanol were weighed. No coupling agent was added. After stirring at 200 r / min for 5 min by a double planetary mixer, it was dried at 250 °C for 12 h to obtain graphene composite material two.

[0074] (3) 1 g of PDMS / three-dimensional graphene, 2 g of PDMS / three-dimensional graphene composite material, 10 g of graphene composite material two, 0.5 g of vinyl silicone oil with a vinyl content of 0.5% and a viscosity of 200 mPa·s, 0.5 g of hydrogen-containing silicone oil with a hydrogen content of 0.4% and a viscosity of 300 mPa·s, 0.01 g of platinum catalyst, and 0.01 g of inhibitor ethynylcyclohexanol were mixed by a double planetary mixer at 800 r / min for 10 min to obtain a mixed solution. The mixed solution was pressed into a sheet with a thickness of 2 mm by a calender and baked at 125 °C for 30 min to obtain a high resilience thermal conductive and wave-absorbing gasket.

[0075] The test results of the material properties of Examples 1-4 and Comparative Examples 1-4 are shown in Table 1:

[0076] Table 1 Test results of the material properties of examples and comparative examples

[0077]

[0078]

[0079] It can be seen from the test data in Table 1 that

[0080] From Examples 1-2 and Comparative Examples 1-2, it can be known that adding freeze-dried three-dimensional graphene composite material and three-dimensional graphene / PDMS material to the system can make full use of the framework effect of three-dimensional graphene. On the one hand, it can improve the electromagnetic modulation ability, increase the multiple absorption and reflection channels of electromagnetic waves, and enhance the wave-absorbing performance; on the other hand, while improving the resilience, the functional properties of the thermal conductive material and wave-absorbing material in the framework are not affected, ensuring the overall resilience and thermal conductive and wave-absorbing performance of the material.

[0081] From Example 3 and Comparative Example 3, it can be known that the three-dimensional graphene composite material treated by freeze-drying was not added in Comparative Example 3. Since the constructed thermal conductive network and wave-absorbing and reflecting network in the system were relatively reduced, the thermal conductivity and wave-absorbing property were both decreased. Obtaining three-dimensional graphene / composite material by freeze-drying is beneficial to the improvement of the overall functionality.

[0082] As can be seen from Example 4 and Comparative Example 4, during the preparation of the graphene composite material II, no coupling agent was added for treatment, resulting in a decrease in the thermal conductivity of the obtained material, a reduction in the peak reflectivity, and a decrease in the resilience. The use of the coupling agent can ensure the uniform distribution of the thermal conductive agent and the wave-absorbing agent in the three-dimensional framework, effectively avoid agglomeration, and fully exert the thermal conductivity and wave-absorbing properties of the material.

[0083] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a three-dimensional graphene thermal conductive and wave-absorbing material, characterized in that, it includes the following steps: Step 1: Preparation of thermal conductive and wave-absorbing fillers A. Subject graphene oxide to solvothermal reaction, and obtain three-dimensional graphene after freeze-drying; B. Mix graphene oxide, thermal conductive powder, and polyethylene glycol, subject to solvothermal reaction, and obtain three-dimensional graphene / composite material I after freeze-drying; C. Mix three-dimensional graphene and three-dimensional graphene / composite material I with polydimethylsiloxane respectively, and obtain PDMS / three-dimensional graphene and PDMS / three-dimensional graphene composite materials after curing; D. After crushing and sieving three-dimensional graphene, mix it with thermal conductive powder and additives in a blender, and obtain three-dimensional graphene composite material II after drying; Step 2: Take PDMS / three-dimensional graphene, PDMS / three-dimensional graphene composite material, and graphene composite material II as thermal conductive and wave-absorbing fillers, and mix them with vinyl silicone oil, hydrogen-containing silicone oil, catalyst, and inhibitor in a blender to obtain a mixed solution; Step 3: Press the mixed solution in Step 2 into a sheet by a calender and cure it to obtain a thermal conductive and wave-absorbing gasket.

2. The preparation method of the three-dimensional graphene thermal conductive and wave-absorbing material according to claim 1, characterized in that, in the said Step A, the preparation method of the three-dimensional graphene: add a reducing agent to the graphene oxide solution, fully dissolve it by ultrasonic wave, react in a reaction kettle at 100°C - 200°C for 15 min - 6 h to obtain a mixed colloidal solution, and dry the mixed colloidal solution in a freeze dryer for 48 h to obtain three-dimensional graphene.

3. The preparation method of the three-dimensional graphene thermal conductive and wave-absorbing material according to claim 2, characterized in that, the concentration of graphene oxide in the graphene oxide solution is 40 - 120 mg / ml; the reducing agent is one or a combination of two or more of vitamin C, ascorbic acid, ethylenediamine, and pyrrole, and the mass ratio of the reducing agent to graphene oxide is (0.5 - 5):

1.

4. The preparation method of the three-dimensional graphene thermal conductive and wave-absorbing material according to claim 1, characterized in that, the preparation methods of the PDMS / three-dimensional graphene and the PDMS / three-dimensional graphene composite material: put three-dimensional graphene and graphene composite material into polydimethylsiloxane respectively to make them completely immersed, and then place them in an oven to evacuate for 15 min to obtain PDMS / three-dimensional graphene material and PDMS / three-dimensional graphene composite material.

5. The preparation method of the three-dimensional graphene thermal conductive and wave-absorbing material according to claim 1, characterized in that, in the said Step 1, the thermal conductive powder is one or a combination of two or more of alumina, aluminum nitride, zinc oxide, boron nitride, silicon nitride, silicon carbide, and aluminum hydroxide; the particle size of the thermal conductive powder is 0.2 μm - 120 μm.

6. The preparation method of the three-dimensional graphene thermal conductive and wave-absorbing material according to claim 1, characterized in that, In step D, it further includes wave-absorbing powder. The thermal conductive powder and the wave-absorbing powder form a thermal conductive and wave-absorbing composite powder. In the thermal conductive and wave-absorbing composite powder, the mass ratio of the thermal conductive powder is 20 - 100%, and the mass ratio of the wave-absorbing powder is 0 - 80%; the proportion of three-dimensional graphene in the total mass is 1 - 5 wt%; the inhibitor is ethynylcyclohexanol, and its proportion in the total mass is 0.01 - 0.5 wt%; the catalyst is a platinum catalyst, and its proportion in the total mass is 0.01 - 1 wt%; the auxiliary agent is one or two or more of silane coupling agent, phthalate coupling agent or absolute ethanol, and its proportion in the total mass is 0.1 - 3 wt%.

7. The preparation method of the three-dimensional graphene thermal conductive and wave-absorbing material according to claim 6, characterized in that, the wave-absorbing powder is one or two or more of carbonyl iron powder, iron-nickel alloy, iron-silicon alloy, iron-aluminum alloy, ferrite, carbon black, carbon nanotube, iron fiber; the particle size of the wave-absorbing powder is 0.1 - 40 μm.

8. The preparation method of the three-dimensional graphene thermal conductive and wave-absorbing material according to claim 1, characterized in that, in step D, the rotation speed of the mixer is 100 - 400 r / min, and the stirring time is 1 - 6 min; in step two, the rotation speed of the mixer is 400 - 1500 r / min, and the stirring time is 5 - 12 min.

9. The preparation method of the three-dimensional graphene thermal conductive and wave-absorbing material according to claim 1, characterized in that, in step three, the curing temperature is 60 - 150 °C, and the time is 20 min - 60 min.

10. A three-dimensional graphene thermal conductive and wave-absorbing material prepared by the preparation method of the three-dimensional graphene thermal conductive and wave-absorbing material according to any one of claims 1 - 9.

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