Preparation method and application of graphene heat-conducting gasket

Abstract

The invention discloses a preparation method and application of a graphene heat-conducting gasket, and relates to the technical field of graphene heat conduction. The invention provides a preparation method of a graphene heat-conducting gasket, the graphene heat-conducting gasket adopts graphene foam as a base material, surface skin removal, laser drilling and trimming, plasma activation treatment and multiple modification treatment are carried out, due to the fact that hydroxyl-rich functional groups are generated on the surface of the graphene through plasma activation treatment, the graphene heat-conducting gasket is prepared through hydroxyl vinyl silicone oil, and the heat-conducting performance of the graphene heat-conducting gasket is improved. A small amount of hydroxyl vinyl silicone oil is uniformly covered on the surface of the graphene, and heating is performed to perform dehydration condensation on the hydroxyl vinyl silicone oil and hydroxyl subjected to plasma activation treatment to form chemical bonds, so that an interface between the graphene and a subsequent adhesive can be tighter, pores at the interface are reduced, and the thermal contact resistance is reduced; the heat transfer efficiency is improved, and the tensile strength and the compression resilience can also be improved.

Description

Technical Field

[0001] The present invention relates to the field of graphene thermal conductivity technology, and in particular to a preparation method of a graphene thermal conductive gasket and application thereof. Background Art

[0002] Graphene thermal pad is a thermal interface material used to improve heat conduction between electronic components and heat sinks. It is made of graphene, which is a single layer of carbon atoms arranged in a honeycomb lattice. It has excellent thermal conductivity. It is generally a thin and flexible sheet placed between the thermal resistor (CPU) and the heat sink to quickly transfer heat from the component to the heat sink. These properties make it widely used in electronic devices.

[0003] Thermal Interface Materials, or TIM for short, is also called thermal interface material or interface thermal conductive material. It is a material commonly used in IC packaging and electronic heat dissipation. It is mainly used to fill the micro gaps and uneven holes generated when two materials are joined or contacted, reduce the heat transfer contact resistance, and improve the heat dissipation performance of the device. Thermal interface heat transfer usually uses a thin and flexible sheet placed between the thermal resistor (CPU) and the heat sink. While having high thermal conductivity, it has good compression and rebound rates, and can quickly transfer heat from the component to the heat sink. It has a wide range of application scenarios in electronic equipment.

[0004] At present, the high thermal conductivity thermal interface materials are liquid metal (40-50W / (m*k)) and thermal grease (less than 10W / (m*k)). Liquid metal is easy to corrode the metal surface in contact, and the main material of the heat sink is aluminum-based, which cannot maintain stable contact for a long time. Thermal grease not only has a low thermal conductivity, but also evaporates small molecular weight silicone oil after long-term use, causing the colloid to dry and crack, and the interface thermal resistance rises rapidly. Therefore, a thermal pad with better performance is urgently needed. Summary of the invention

[0005] The main purpose of the present invention is to provide a preparation method and application of a graphene thermally conductive gasket, aiming to improve the strength of the graphene thermally conductive gasket while taking into account the thermal conductivity and resilience performance.

[0006] To achieve the above object, the present invention provides a method for preparing a graphene thermally conductive gasket, the preparation steps comprising:

[0007] S10, providing a plurality of graphene foams;

[0008] S20, removing the surface hard skin of the plurality of graphene foams, laser drilling and trimming, and plasma activation to obtain activated graphene foams, and subjecting the activated graphene foams to a first modification treatment with hydroxy vinyl silicone oil to obtain a plurality of first graphene foams;

[0009] S30. Perform a second modification treatment on the multiple first graphene foams with an adhesive to obtain multiple second graphene foams;

[0010] S40. Bond and press the multiple second graphene foams in the thickness direction to form a block, and cure it to obtain a third graphene foam;

[0011] S50. Cut the third graphene foam into sheets in the thickness direction to obtain a graphene thermal conductive gasket, wherein the adhesive includes: linear low molecular weight vinyl silicone oil, linear medium molecular weight vinyl silicone oil, linear high molecular weight vinyl silicone oil, crosslinking agent, chain extender, reinforcing agent, toughening agent, the catalyst and the inhibitor.

[0012] In one embodiment, in step S10:

[0013] The average density of the graphene foam is 0.15 - 0.25 g / cm 3 ; and / or,

[0014] The thermal diffusivity of the graphene foam is ≥600 mm 2 / s; and / or,

[0015] The thickness of the graphene foam is 200 - 300 μm.

[0016] In one embodiment, in step S20:

[0017] The step of removing the surface hard skin includes: crushing and adhering the surface hard skin to remove the surface hard skin; and / or,

[0018] After the step of laser punching and trimming, the average pore diameter of the holes is 10 - 200 μm, and the distance between the holes is 100 - 4000 μm; and / or,

[0019] The step of plasma activation treatment includes: performing treatment with a direct injection type plasma activation treatment device; and / or,

[0020] The step of the first modification treatment includes: coating the activated graphene foam with hydroxy vinyl silicone oil diluted with xylene, and performing vacuum heating treatment after complete absorption to obtain multiple first graphene foams, wherein the coating is: spraying 3 - 9 mg of hydroxy vinyl silicone oil corresponding to each square centimeter of the activated graphene foam.

[0021] In one embodiment, in step S30, the step of the second modification treatment includes: spraying the adhesive on the multiple first graphene foams for mixing to obtain multiple second graphene foams, wherein the spraying is: spraying 70 - 110 mg of the adhesive corresponding to each square centimeter of the first graphene foam.

[0022] In one embodiment, the adhesive includes linear low molecular weight vinyl silicone oil, linear medium molecular weight vinyl silicone oil, linear high molecular weight vinyl silicone oil, a crosslinking agent, a chain extender, a reinforcing agent, a toughening agent, the catalyst and the inhibitor. The linear low molecular weight vinyl silicone oil is 50 cp vinyl silicone oil, the linear medium molecular weight vinyl silicone oil is 500 cp vinyl silicone oil, and the linear high molecular weight vinyl silicone oil is 20,000 cp vinyl silicone oil. Among them,

[0023] the mass ratio between the 50 cp vinyl silicone oil, the 500 cp vinyl silicone oil, the 20,000 cp vinyl silicone oil, the chain extender, the crosslinking agent, the reinforcing agent, the toughening agent, the catalyst and the inhibitor is (20 - 50):(60 - 130):(30 - 50):(15 - 25):(20 - 30):(3 - 5):(0.5 - 1.5):(0.3 - 0.6):(0.08 - 0.12); and / or,

[0024] the mass ratio between the first graphene foam and the adhesive is 1:(1 - 3).

[0025] In one embodiment, in the adhesive:

[0026] the linear low molecular weight vinyl silicone oil includes low molecular weight silicone oil with a viscosity below 500 cp; and / or,

[0027] the linear medium molecular weight vinyl silicone oil includes medium molecular weight silicone oil with a viscosity between 500 cp and 5000 cp; and / or,

[0028] the linear high molecular weight vinyl silicone oil includes high molecular weight silicone oil with a viscosity above 5000 cp; and / or,

[0029] the crosslinking agent includes side hydrogen silicone oil; and / or,

[0030] the chain extender includes end hydrogen silicone oil; and / or,

[0031] the reinforcing agent includes MQ resin; and / or,

[0032] the toughening agent includes nano - scale fumed silica; and / or,

[0033] the catalyst includes platinum catalyst; and / or,

[0034] the inhibitor includes alkynol inhibitor.

[0035] In one embodiment, the preparation steps of the adhesive include: mixing the linear low molecular weight vinyl silicone oil, the linear medium molecular weight vinyl silicone oil, the linear high molecular weight vinyl silicone oil, the crosslinking agent, the chain extender, the catalyst, the inhibitor, the reinforcing agent and the toughening agent.

[0036] In one embodiment, in step S40, the thickness of the third graphene foam is 40 - 50 mm; and / or,

[0037] In step S50, the thickness of the graphene thermal conductive gasket is 0.3 - 2.0 mm.

[0038] The present invention also provides a graphene thermal conductive gasket, which comprises the graphene thermal conductive gasket prepared by the preparation method of the graphene thermal conductive gasket as described above.

[0039] The technical solution of the present invention provides a preparation method of a graphene thermal conductive gasket. The graphene thermal conductive gasket uses graphene foam as the base material and undergoes surface skin removal, laser punching and edge cutting, plasma activation treatment, and multiple modification treatments. Due to the plasma activation treatment, hydroxyl functional groups are generated on the graphene surface. Through hydroxyl vinyl silicone oil, a small amount of hydroxyl vinyl silicone oil is evenly covered on the graphene surface. Heating causes the hydroxyl vinyl silicone oil to undergo dehydration condensation with the hydroxyl groups after plasma activation treatment to form chemical bonds, which can make the interface between the graphene and the subsequent adhesive closer, reduce the pores at the interface, thereby reducing the thermal contact thermal resistance, improving the heat transfer efficiency, and also improving the tensile strength and compression resilience. Detailed Embodiments

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. For those not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments not indicated by the manufacturer can be obtained as conventional products through commercial purchase. In addition, the meaning of "and / or" appearing throughout the text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or the solution where A and B are satisfied simultaneously. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the premise that those skilled in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0041] Graphene thermal pads are a type of thermal interface material used to improve heat conduction between electronic components and heat sinks. They are made from graphene, which is a single layer of carbon atoms arranged in a honeycomb lattice and has excellent thermal conductivity. Generally, they are thin and flexible sheets placed between heat-resistant components (CPUs) and heat sinks, quickly transferring heat from the components to the heat sinks. These properties enable their wide application in electronic devices.

[0042] Currently, high thermal conductivity thermal interface materials are liquid metals (40 - 50 W / (m*k)) and thermal greases (below 10 W / (m*k)). Among them, liquid metals are prone to corroding the metal surfaces they come into contact with, and the main material of heat sinks is aluminum-based, so they cannot maintain contact stably for a long time. Thermal greases not only have insufficient thermal conductivity coefficients, but also during long-term use, small molecular weight silicone oil volatilizes, causing the colloid to dry and crack, and the interface thermal resistance to rise rapidly.

[0043] In view of this, to achieve the above objectives, the present invention provides a preparation method for graphene thermal pads, and the preparation steps include:

[0044] S10. Provide a plurality of graphene foams;

[0045] S20. Remove the surface crusts of the plurality of graphene foams, perform laser drilling and edge cutting, and plasma activation on them to obtain activated graphene foams. Then, perform a first modification treatment on the activated graphene foams with hydroxy vinyl silicone oil to obtain a plurality of first graphene foams;

[0046] S30. Perform a second modification treatment on the plurality of first graphene foams with an adhesive to obtain a plurality of second graphene foams;

[0047] S40. Bond and press the plurality of second graphene foams in the thickness direction into a block and cure it to obtain a third graphene foam;

[0048] S50. Cut the third graphene foam into sheets in the thickness direction to obtain graphene thermal pads, where the adhesive includes: linear low molecular weight vinyl silicone oil, linear medium molecular weight vinyl silicone oil, linear high molecular weight vinyl silicone oil, crosslinking agent, chain extender, reinforcing agent, toughening agent, the catalyst, and the inhibitor.

[0049] In the technical solution of the present invention, the graphene thermal pads use graphene foam as the base material. Through surface skin removal, laser drilling and edge cutting, plasma activation treatment, and multiple modification treatments, the thermal pads can better contact the components and effectively fill air gaps, which not only significantly improves the heat transfer efficiency, but also improves the tensile strength and compression resilience.

[0050] Furthermore, in step S20, the plasma activation treatment causes hydroxyl functional groups to be generated on the surface of graphene. The hydroxyl vinyl silicone oil diluted with xylene can reduce the viscosity of the silicone oil, enabling the hydroxyl vinyl silicone oil to uniformly cover the surface of graphene. Heating causes dehydration condensation between the hydroxyl vinyl silicone oil and the hydroxyl groups after plasma activation treatment to form chemical bonds, which can make the interface between graphene and the subsequent adhesive closer, reduce the pores at the interface, thereby reducing the thermal contact thermal resistance, improving the heat transfer efficiency, and also improving the tensile strength and compression resilience.

[0051] In some embodiments of the present invention, in step S10, a plurality of graphene foams are provided;

[0052] Graphene foam is a three-dimensional porous material composed of graphene or its derivatives, with a structure similar to that of a sponge. This material combines the unique physical and chemical properties of graphene with the lightweight and high specific surface area characteristics of foam materials. Its high thermal conductivity makes it possible to be used as the base material for graphene thermal conductive gaskets.

[0053] Furthermore, in step S10: the average density of the graphene foam is 0.2 - 0.3 g / cm 3 , within this density range, the graphene foam has relatively high flexibility and thermal conductivity; the thermal diffusivity of the graphene foam is ≥600 mm 2 / s; the thickness of the graphene foam is 200 - 300 μm. The higher the density, the higher the thermal diffusivity, but the flexibility decreases. To balance thermal conductivity and flexibility, a sample with a density of 0.2 - 0.3 g / cm 3 is selected. The thicker the thickness, the higher the production cost of the foam, and the fewer the graphene interfaces, resulting in improved anti-cracking. To balance cost and performance, a thickness of 200 - 300 μm is selected.

[0054] In some embodiments of the present invention, in step S20, the step of removing the surface hard skin includes: crushing and adhering the surface hard skin to remove the hard skin.

[0055] Specifically, the operation of the step of removing the surface hard skin is as follows: Adjust the laser focusing focal length of the laser drilling machine. The laser scans the surface of the sample at an appropriate speed. When the laser irradiates, the local area is heated and softened, and when the laser moves away, it is cooled and embrittled. The thermal expansion and contraction cause the surface hard skin to break into small pieces, which will not damage the internal foam during subsequent removal. Then, specifically adjust the double-roll roller press, and the distance between the two rollers is the same as that of the graphene foam. Uniformly paste double-sided tape on the outside of the two rollers to facilitate subsequent removal of the hard skin. Insert the graphene foam horizontally from one side into the space between the two rollers, and the fragmented hard skin on the surface of graphene can be effectively removed through the adhesive force of the double-sided tape. Repeat replacing the double-sided tape to remove the hard skin of all the required graphene foams. Although the surface hard skin has a high thermal conductivity, it has a high hardness in the vertical arrangement, and it is brittle and does not have flexibility when stressed and fractured.

[0056] In some embodiments of the present invention, in the step of laser drilling and trimming, the average pore diameter of the holes is 10 - 200 μm, and the distance between the holes is 100 - 4000 μm.

[0057] It can be understood that during the preparation of the graphene foam, the outermost layer loses moisture or heat faster than the interior, which causes the surface of the graphene foam to be denser and have fewer pores than its interior. Moreover, the graphene foam produced by coating has a low density and needs to be densified and its thermal conductivity improved by a roller press. During the rolling process, the external and internal foams are unevenly stressed, which also results in a higher density, higher crystallinity, and higher hardness of the outer graphene. This forms a relatively dense "skin" that is prone to breakage under stress, interrupting the heat conduction path, thereby reducing the thermal conductivity. Additionally, the denser surface also reduces the flexibility of the graphene foam, making it unable to rebound to a certain height after the stress is removed. Removing it can make the graphene foam more flexible, thus better conforming to the uneven surface of the electronic component, which can ensure a lower contact thermal resistance and minimize the air gap that hinders heat conduction.

[0058] In some embodiments of the present invention, in step S20, the step of laser drilling and trimming includes: laser drilling and trimming are performed on multiple graphene foams placed on a laser drilling platform. The purpose of laser drilling is to provide a channel for subsequent reactants to enter the interior of the graphene foam, facilitating subsequent reactions.

[0059] Furthermore, in step S20, the plasma activation treatment step includes: using a direct injection type plasma activation treatment device for treatment. The specific steps include: setting a "Z" - shaped route to perform plasma activation treatment on the entire surface, which can evenly activate the graphene surface. After the plasma activation of the graphene foam, the surface has abundant hydroxyl groups, providing abundant reactive sites and enhancing the surface activity of the graphene.

[0060] In some embodiments of the present invention, the first modification treatment step includes: coating the activated graphene foam with hydroxyvinyl silicone oil diluted with xylene, and then performing vacuum heating treatment after complete absorption to obtain multiple first graphene foams. Among them, the coating is: for each square centimeter of the activated graphene foam, 3 - 9 mg of hydroxyvinyl silicone oil is sprayed correspondingly. This is to make the hydroxyl groups generated by plasma activation react with the hydroxyl groups of hydroxyvinyl silicone oil to form new chemical bonds. By reacting the hydroxyvinyl silicone oil with the hydroxyl groups on the surface of the graphene foam, stable chemical bonds are formed, enhancing the bonding force between the coating and the substrate, preventing the coating from peeling off, and improving the mechanical strength and chemical stability.

[0061] In some embodiments of the present invention, in step S30, the second modification treatment step includes: mixing and spraying the adhesive with the plurality of first graphene foams until evenly mixed to obtain a plurality of second graphene foams, wherein the spraying is: 70-110 mg of the adhesive is sprayed corresponding to each square centimeter of the first graphene foam. Here, the performance of the graphene foam is improved by spraying the adhesive on the first graphene foam.

[0062] In some embodiments of the present invention, the adhesive includes linear low molecular weight vinyl silicone oil, linear medium molecular weight vinyl silicone oil, linear high molecular weight vinyl silicone oil, crosslinking agent, chain extender, reinforcing agent, toughening agent, the catalyst and the inhibitor. The linear low molecular weight vinyl silicone oil is 50 cp vinyl silicone oil, the linear medium molecular weight vinyl silicone oil is 500 cp vinyl silicone oil, and the linear high molecular weight vinyl silicone oil is 20,000 cp vinyl silicone oil. Among them,

[0063] The mass ratio between the 50 cp vinyl silicone oil, the 500 cp vinyl silicone oil, the 20,000 cp vinyl silicone oil, the chain extender, the crosslinking agent, the reinforcing agent, the toughening agent, the catalyst and the inhibitor is (20-50):(60-130):(30-50):(15-25):(20-30):(3-5):(0.5-1.5):(0.3-0.6):(0.08-0.12).

[0064] In the technical solution of the present invention, by optimizing the strength, toughness and surface adhesiveness of the cured adhesive, the quality of the final product, the graphene thermal conductive gasket, is improved. The addition of low molecular weight silicone oil ensures that the adhesive has a low viscosity, which is convenient for the graphene foam to absorb after spraying. The medium molecular weight silicone oil has a moderate molecular weight, balancing viscosity and strength. The high molecular weight silicone oil increases the elongation at break of the adhesive. MQ resin is used as a reinforcing agent to increase the toughness after curing, and fumed silica increases the toughness after curing. Within the above ratio range, the prepared adhesive has a better adhesion effect with the graphene foam, improving the performance of the graphene foam.

[0065] In some embodiments of the present invention, the mass ratio of the first graphene foam to the adhesive is 1:(1-3).

[0066] In some embodiments of the present invention, in the adhesive, the linear low molecular weight vinyl silicone oil is a low molecular weight silicone oil with a viscosity range of less than 500 cp, having a low viscosity and abundant reactive functional groups, providing better fluidity and absorption for the adhesive; the linear medium molecular weight vinyl silicone oil includes a medium molecular weight silicone oil with a viscosity of 500 cp - 5000 cp. The linear medium molecular weight vinyl silicone oil is a double-end vinyl linear silicone oil with a viscosity range above 500 cp and below 5000 cp, having an appropriate viscosity and appropriate reactive functional groups, providing a medium strength after curing. The double-end vinyl linear silicone oil with a viscosity range above 500 cp and below 5000 cp has an appropriate viscosity and appropriate reactive functional groups, making the strength after curing moderate; the linear high molecular weight vinyl silicone oil includes VS20000. The linear high molecular weight vinyl silicone oil is a double-end vinyl linear silicone oil with a viscosity range above 5000 cp, having a high viscosity and a small number of reactive functional groups, providing a high strength after curing.

[0067] The crosslinking agent includes side hydrogen silicone oil; and / or,

[0068] The chain extender includes end hydrogen silicone oil; and / or,

[0069] The reinforcing agent includes MQ resin; and / or,

[0070] The toughening agent includes nano-sized fumed silica.

[0071] In some embodiments of the present invention, the preparation steps of the adhesive include: mixing the linear low molecular weight vinyl silicone oil, the linear medium molecular weight vinyl silicone oil, the linear high molecular weight vinyl silicone oil, the crosslinking agent, the chain extender, the catalyst, the inhibitor, the reinforcing agent, and the toughening agent.

[0072] In some embodiments of the present invention, in step S40: the thickness of the third graphene foam is 40 - 50 mm, which can be flexibly adjusted according to test requirements.

[0073] In some embodiments of the present invention, in step S50: the thickness of the graphene thermal conductive gasket is 0.3 - 2.0 mm. Within this range, it not only ensures that the inherent high thermal conductivity of graphene can be fully exerted, enabling heat to be quickly transferred from the heat source to the radiator or other cooling devices, improving the heat exchange efficiency of the entire system, but also can adapt to contact surfaces of different shapes and sizes, ensuring good fit, reducing air gaps, and thus reducing thermal resistance.

[0074] The present invention also provides a graphene thermal conductive gasket, which comprises the graphene thermal conductive gasket prepared by the preparation method of the graphene thermal conductive gasket as described above. The graphene thermal conductive gasket has all the beneficial effects of the above preparation method, which will not be elaborated herein one by one.

[0075] The technical solution of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0076] Experimental materials

[0077] Hydroxy vinyl silicone oil is from Zhejiang Zhenghe 207V-2.5;

[0078] The following silicone oils are all from Ambia Special Organosilicon (Nantong) Co., Ltd. Only the specific models are written below:

[0079] The 50cp vinyl silicone oil model is VS 50;

[0080] The 500cp vinyl silicone oil model is VS 500;

[0081] The 2w cp vinyl silicone oil model is VS20000;

[0082] The 0.2% terminal hydrogen silicone oil model is CE 100;

[0083] The 0.34% side hydrogen silicone oil model is XL 12;

[0084] The MQ resin is from Kangda Technology VMQ-2709;

[0085] The nano-scale fumed silica is from Hubei Huifu Nano Materials HB139.

[0086] Example 1

[0087] A preparation method of a graphene thermal conductive gasket, the preparation steps include:

[0088] S10. Provide 43 graphene foams with a thermal diffusivity of 650mm 2 / s, a density of 0.2g / cm 3 . The graphene foam with length, width and height of 100*100*350mm respectively;

[0089] S20. Adsorb 43 pieces of the graphene foam on the surface with a vacuum table and use a laser drilling machine. Set the laser with a power of 1500w to focus 2mm above the graphene surface to form an effective circle with a diameter of 1mm, and quickly translate and scan the laser for processing at a speed of 10mm / s. Paste a bonding area with the same width as the graphene foam on a roller press with a diameter of 300mm. After adjusting the distance between the two rollers to be the same as that of the graphene foam, feed the graphene foam from one side, that is, perform a surface hard skin removal operation on a partial area, and repeat the operation to remove the hard skin on the entire graphene surface to obtain 43 pieces of the first graphene foam with a thickness of 300μm (±15μm) after removing the hardening epidermis;

[0090] S30. Perform laser drilling and edge cutting on 43 pieces of the first graphene foam: Place 43 pieces of the first graphene foam on the laser drilling platform and perform laser drilling and edge cutting operations simultaneously. The aperture is 50μm, the hole pitch is 1000μm, and the upper and lower two rows are staggered by 1000μm and arranged in a repeated pattern of A / B / A / B. The edge cutting size is 50mm * 50mm to facilitate subsequent plasma activation treatment;

[0091] The specific treatment method of the plasma activation treatment is as follows: Place the sample in a grid plate frame, use a direct injection type plasma activation treatment device, set the power to 800w, the horizontal height of the spray gun from the sample is 10mm, the size of the spray gun nozzle is a circle with a diameter of 10mm, and use the projection method to calculate that the effective treatment area is a circle with a diameter of 20mm. Therefore, the moving speed of the spray gun is 5mm / s, and it moves down 20mm when changing lines. Set a "Z" - shaped route to perform plasma activation treatment on the entire surface to obtain the activated graphene foam;

[0092] Spray the activated graphene foam and hydroxyvinyl silicone oil diluted 10 times with xylene evenly on the surface of the graphene foam through a spraying machine, and control the spraying amount to be 6mg / cm 2 . Wait for the hydroxyvinyl silicone oil to be fully absorbed to obtain 43 pieces of the first graphene foam; Then perform a second modification treatment on 43 pieces of the first graphene foam and the adhesive. The specific steps of the treatment are as follows: Spray the adhesive on the multiple first graphene foams for mixing to obtain multiple second graphene foams, and control the spraying amount to be 90mg of the adhesive corresponding to each square centimeter of the first graphene foam. That is, obtain 172 pieces of the second graphene foam with a size of 50 * 50mm;

[0093] S40. Place 172 pieces of the second graphene foam on the inner layer of the mold and stack them together. After stacking all 172 pieces, place a 50*50*5 mm square aluminum block on each of the upper and lower sides. Use an automatic propulsion device to apply a certain pressure to the aluminum blocks so that the graphene foams are closely attached to each other. Lock the aluminum blocks when the overall distance between the aluminum blocks is 51.6 mm. Place the entire device in an oven and heat it at 120 °C for 2 h to obtain the third graphene foam;

[0094] S50. Take the third graphene foam out of the oven, take it out of the module, cut off the residual glue on the surface with a knife, and place it on the operating table of a diamond cutting machine. Set the cutting thickness to 300 μm and cut it into slices along the thickness direction to obtain a graphene thermal conductive gasket;

[0095] Among them, the specific components and dosages of the adhesive are as follows: 20 parts of 50 cp vinyl silicone oil, 100 parts of 500 cp vinyl silicone oil, 30 parts of 20000 cp vinyl silicone oil, 20 parts of 0.2% terminal hydrogen silicone oil, 25 parts of 0.34% side hydrogen silicone oil, 4 parts of MQ resin, 1 part of nano-level fumed silica, 0.5 part of 5000 ppm platinum catalyst, and 0.1 part of alkynol inhibitor.

[0096] Example 2

[0097] Different from Example 1, the specific components and dosages of the adhesive used in Example 2 are as follows: 50 parts of 50 cp vinyl silicone oil, 70 parts of 500 cp vinyl silicone oil, 30 parts of 20000 cp vinyl silicone oil, 15 parts of 0.2% terminal hydrogen silicone oil, 20 parts of 0.34% side hydrogen silicone oil, 3 parts of MQ resin, 0.5 part of nano-level fumed silica, 0.3 part of 5000 ppm platinum catalyst, and 0.08 part of alkynol inhibitor.

[0098] Example 3

[0099] Different from Example 1, the specific components and dosages of the adhesive used in Example 3 are as follows: 20 parts of 50 cp vinyl silicone oil, 70 parts of 500 cp vinyl silicone oil, 60 parts of 20000 cp vinyl silicone oil, 20 parts of 0.2% terminal hydrogen silicone oil, 25 parts of 0.34% side hydrogen silicone oil, 4 parts of MQ resin, 1 part of nano-level fumed silica, 0.5 part of 5000 ppm platinum catalyst, and 0.1 part of alkynol inhibitor.

[0100] Example 4

[0101] Different from Example 1, the specific components and dosages of the adhesive used in Example 4 are as follows: 30 parts of 50 cp vinyl silicone oil, 130 parts of 500 cp vinyl silicone oil, 40 parts of 20,000 cp vinyl silicone oil, 20 parts of 0.2% terminal hydrogen silicone oil, 25 parts of 0.34% side hydrogen silicone oil, 4 parts of MQ resin, 1 part of nano-sized fumed silica, 0.5 part of 5000 ppm platinum catalyst, and 0.1 part of alkynol inhibitor.

[0102] Example 5

[0103] The difference from Example 1 lies only in the components and dosages of the adhesive. Specifically, the specific formula of the adhesive in Example 5 is as follows: 40 parts of 500 cp vinyl silicone oil, 60 parts of cp vinyl silicone oil, 50 parts of 20,000 cp vinyl silicone oil, 25 parts of 0.2% terminal hydrogen silicone oil, 30 parts of 0.34% side hydrogen silicone oil, 5 parts of MQ resin, 1.5 parts of nano-sized fumed silica, 0.6 part of 5000 ppm platinum catalyst, and 0.12 part of alkynol inhibitor.

[0104] Comparative Example 1

[0105] The difference from Example 1 is that the step of "mixing the activated graphene foam with hydroxy vinyl silicone oil in a mass ratio of 1:1.5 to obtain 43 pieces of the first graphene foam" is removed, and no modification treatment is carried out.

[0106] Performance Test

[0107] (1) Heat Transfer Efficiency Test

[0108] The graphene thermal conductive gaskets prepared in Examples 1 to 4 were subjected to heat transfer efficiency tests. The test standard was ASTM D5470. The test method was as follows: Take a sample with dimensions of 2.54 cm * 2.54 cm * 300 μm (length * width * height), set the parameters as a heat source of 80 °C, a pressure of 20 psi, and a test time of 25 min. The test results are shown in Table 1:

[0109] Table 1

[0110] Test Items Thermal Conductivity (w / m*k) Example 1 24.89 Example 2 17.57 Example 3 25.03 Example 4 25.40 Example 5 25.32 Comparative Example 1 10.11

[0111] (2) Tensile Strength Test

[0112] Test standard: GBIT 528 - 2009;

[0113] Test method: Prepare the sample into a dumbbell-shaped tensile spline with a thickness of 0.3 mm and a width of 10 mm, and conduct a tensile test at a speed of 300 mm / min. Record the tensile strength along the orientation direction and the direction perpendicular to the orientation. The test results are shown in Table 2:

[0114] Table 2

[0115] Test Items Tensile Strength (Mpa) Example 1 0.083 Example 2 0.095 Example 3 0.051 Example 4 0.036 Example 5 0.028 Comparative Example 1 0.017

[0116] (3) Compression and Rebound Performance Test

[0117] Test Standard: GB / T 528-2009;

[0118] Test Method: Take indenter samples of the same size with an indenter of the same size, maintain a 50% compression amount for 30 min, record the compression amount, then remove the pressure and rebound for 10 min, and record the rebound amount. The rebound rate is calculated as = rebound amount / compression amount * 100%, and the results are shown in Table 3:

[0119] Table 3

[0120] Test Items Compression Rebound Rate (%) Example 1 94 Example 2 98 Example 3 90 Example 4 83 Example 5 79 Comparative Example 1 89

[0121] (4) Anti-Cracking Test under Ultimate Pressure;

[0122] Test Method: Place a graphene standard-sized sample (25.4 mm long and wide, 300 μm thick) under a universal testing machine. At different compression ratios (observe once for every 5% increase in compression ratio starting from 0), maintain the pressure for 30 min each time, remove the pressure and observe whether the sample cracks, and record the compression ratio at which cracking occurs. The test results are shown in Table 4:

[0123] Table 4

[0124] Test Items Compression Ratio at Cracking (%) Example 1 75 Example 2 40 Example 3 75 Example 4 80 Example 5 85 Comparative Example 1 10

[0125] In summary, it can be seen that through multiple modification treatments, the present invention enables the thermal conductive gasket to better contact the components and effectively fill the air gaps, thereby improving the performance of the graphene thermal conductive gasket.

[0126] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the patent protection scope of the present invention.

Claims

1. A method for preparing a graphene thermally conductive pad, characterized in that: The preparation steps include: S10, providing a plurality of graphene foams; S20, removing the surface hard skin of the plurality of graphene foams, laser drilling and trimming, and plasma activation to obtain activated graphene foams, and subjecting the activated graphene foams to a first modification treatment with hydroxy vinyl silicone oil to obtain a plurality of first graphene foams; S30, subjecting the plurality of first graphene foams and the adhesive to a second modification treatment to obtain a plurality of second graphene foams; S40, bonding and pressing the plurality of second graphene foams in a thickness direction into a block, and curing the blocks to obtain a third graphene foam; S50, cutting the third graphene foam into sheets along the thickness direction to obtain a graphene thermal conductive gasket, wherein the adhesive comprises: linear low molecular weight vinyl silicone oil, linear medium molecular weight vinyl silicone oil, linear high molecular weight vinyl silicone oil, a cross-linking agent, a chain extender, a reinforcing agent, a toughening agent, the catalyst and the inhibitor.

2. The method for preparing the graphene thermally conductive pad according to claim 1, characterized in that: In step S10: The average density of the graphene foam is 0.15-0.25 g / cm 3 and / or, The thermal diffusion coefficient of the graphene foam is ≥600 mm 2 / s; and / or, The graphene foam has a thickness of 200-300 μm.

3. The method for preparing the graphene thermally conductive pad according to claim 1, characterized in that: In step S20: The step of removing the surface crust comprises: crushing and adhering the surface crust to remove the surface crust; and / or, After the laser drilling and trimming step, the average pore size of the pores is 10 to 200 μm, and the distance between the pores is 100 to 4000 μm; and / or, The plasma activation treatment step includes: using a direct injection plasma activation treatment device for treatment; and / or, The first modification treatment step includes: coating the activated graphene foam with hydroxy vinyl silicone oil diluted with xylene, and performing vacuum heating treatment after complete absorption to obtain a plurality of first graphene foams, wherein the coating is: spraying 3 to 9 mg of hydroxy vinyl silicone oil per square centimeter of the activated graphene foam.

4. The method for preparing the graphene thermally conductive pad according to claim 1, characterized in that: In step S30, the second modification treatment step includes: spraying the adhesive onto the plurality of first graphene foams for mixing to obtain a plurality of second graphene foams, wherein the spraying is: 70 to 110 mg of the adhesive is sprayed per square centimeter of the first graphene foam.

5. The method for preparing the graphene thermally conductive pad according to claim 4, characterized in that: The adhesive comprises linear low molecular weight vinyl silicone oil, linear medium molecular weight vinyl silicone oil, linear high molecular weight vinyl silicone oil, crosslinking agent, chain extender, reinforcing agent, toughening agent, the catalyst and the inhibitor, wherein the linear low molecular weight vinyl silicone oil is 50cp vinyl silicone oil, the linear medium molecular weight vinyl silicone oil is 500cp vinyl silicone oil, the linear high molecular weight vinyl silicone oil is 2w cp vinyl silicone oil, wherein: The mass ratio of the 50cp vinyl silicone oil, the 500cp vinyl silicone oil, the 2wcp vinyl silicone oil, the chain extender, the crosslinker, the reinforcing agent, the toughening agent, the catalyst and the inhibitor is (20-50): (60-130): (30-50): (15-25): (20-30): (3-5): (0.5-1.5): (0.3-0.6): (0.08-0.12); and / or, The mass ratio of the first graphene foam to the adhesive is 1:(1-3).

6. The method for preparing the graphene thermally conductive pad according to claim 5, characterized in that: In the adhesive: The linear low molecular weight vinyl silicone oil comprises a low molecular weight silicone oil having a viscosity below 500 cp; and / or, The linear medium molecular weight vinyl silicone oil includes a medium molecular weight silicone oil with a viscosity of 500cp-5000cp; and / or, The linear high molecular weight vinyl silicone oil includes a high molecular weight silicone oil with a viscosity of more than 5000 cp; and / or, The cross-linking agent includes penetrating hydrogen silicone oil; and / or, The chain extender includes hydrogen-terminated silicone oil; and / or, The reinforcing agent comprises MQ resin; and / or, The toughening agent includes nano-scale fumed silica; and / or, The catalyst comprises a platinum catalyst; and / or, Such inhibitors include alkynol inhibitors.

7. The method for preparing the graphene thermally conductive gasket according to any one of claims 5 to 6, characterized in that: The preparation steps of the adhesive include: mixing the linear low molecular weight vinyl silicone oil, the linear medium molecular weight vinyl silicone oil, the linear high molecular weight vinyl silicone oil, the crosslinking agent, the chain extender, the catalyst, the inhibitor, the reinforcing agent and the toughening agent.

8. The method for preparing the graphene thermally conductive pad according to claim 1, characterized in that: In step S40, the thickness of the third graphene foam is 40-50 mm; and / or, In step S50, the thickness of the graphene thermal conductive gasket is 0.3-2.0 mm.

9. A graphene thermally conductive pad, characterized in that: The graphene thermally conductive gasket comprises a graphene thermally conductive gasket prepared by the method for preparing a graphene thermally conductive gasket according to any one of claims 1 to 8.