A method for producing a heat-conducting gasket

Abstract

The application discloses a preparation method of a heat-conducting gasket, comprising the following steps: providing a template with a meandering structure, preparing a graphene film at the meandering structure of the template, and forming a curved structure corresponding to the meandering structure; stacking a plurality of the graphene films with the curved structure, and bonding and fixing adjacent graphene films by using an adhesive to form a graphene stack; and compressing the graphene stack, and the compression direction intersects with the stacking direction of the graphene stack. The preparation method of the heat-conducting gasket is used for providing a heat-conducting gasket with stable structure and low compression modulus.

Description

Technical Field

[0001] This invention relates to the field of thermal conductive materials technology, and in particular to a method for preparing a thermally conductive pad. Background Technology

[0002] Thermal pads are installed between heat-generating elements and heat sinks. Heat generated by the heat-generating element is conducted towards the heat sink through the thermal pad, improving the heat dissipation effect of the heat-generating element. Graphene, as a two-dimensional material with ultra-high thermal conductivity, can be used to fabricate thermal pads with high thermal conductivity. The fabrication process typically involves stacking planar graphene layers and bonding them together with an adhesive, then cutting along the stacking direction to form the thermal pad. While this type of graphene thermal pad has a high thermal conductivity, it suffers from high compressive modulus and poor compressive performance. The high compressive modulus severely limits the application scenarios of these thermal pads.

[0003] Chinese invention patent CN120622474A discloses a compressible, high thermal conductivity graphene thermal interface material. This material is formed by stacking and bonding graphene sheets to create graphene structural units, and then applying shear stress to these units to create a continuous buckling structure. By establishing this continuous buckling structure within the graphene structural units and using a relatively low thickness (<500 nm), the compressive modulus of the dense vertical graphene array is reduced. However, the method of using shear stress to create the continuous buckling structure is unstable and difficult to control.

[0004] Chinese invention patent CN119953034B discloses a high-compression-resilience thermal interface material and its preparation method. It improves compression resilience by introducing high thermal conductivity fibers and elastic polymers between graphene sheets, causing the graphene sheets to form a curved structure on the fiber surface under pressure. However, the high thermal conductivity fibers used in this method form a rigid structure in the pad, resulting in a limited reduction in compressive modulus. Furthermore, at least some of the high thermal conductivity fibers are oriented in a direction inconsistent with the desired thermal conductivity, leading to relatively low gains in the thermal conductivity of the pad.

[0005] Chinese invention patent CN119797347A discloses a method for preparing a graphene film, a graphene thermal conductive component, and the same method. It involves preparing a graphene oxide film on a periodically wrinkled template and then thermally reducing it to obtain a wrinkled graphene film. The wrinkled graphene films are then stacked and solidified to form a thermal conductive component. However, the thermal reduction of the wrinkled graphene oxide film in this method is a foaming process that releases a large amount of gas. This can easily lead to deformation or disappearance of the wrinkles in the graphene film obtained by reduction, resulting in limited effectiveness in reducing the compressive modulus. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a thermally conductive pad, which provides a thermally conductive pad with stable structure and low compressive modulus.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A method for preparing a thermally conductive pad, comprising:

[0009] A template with a tortuous structure is provided, and a graphene film is prepared at the tortuous structure of the template, wherein the graphene film forms a curved structure corresponding to the tortuous structure;

[0010] Multiple graphene films with curved structures are stacked and adjacent graphene films are bonded together with an adhesive to form a graphene stack.

[0011] The graphene stack is compressed in a direction that intersects with the stacking direction of the graphene stack.

[0012] Preferably, the compression direction when compressing the graphene stack is the orientation direction of the graphene in the thermal pad.

[0013] And / or, the stacking direction of the plurality of graphene films is perpendicular to the orientation direction of the graphene in the thermal pad, and the bending direction of the graphene films is parallel to the stacking direction of the plurality of graphene films.

[0014] Preferably, one side of the template is provided with a curved surface, graphene slurry is coated on the curved surface to form a graphene wet film, the graphene wet film is dried and the dried film layer is separated from the template to obtain the graphene film.

[0015] Preferably, the graphene slurry is prepared by the following steps: adding a thickener to water to dissolve it and obtain a base liquid, adding graphene microsheets to the base liquid and stirring and dispersing them to obtain the graphene slurry;

[0016] The graphene content in the graphene slurry is 1 wt.% to 10 wt.%.

[0017] Preferably, the particle size D50 of the graphene microflakes is <10 μm, and the particle size D... max <25μm;

[0018] And / or, the thickener is one or more of sodium carboxymethyl cellulose, hydroxyethyl cellulose, guar gum, and xanthan gum, and the content of the thickener in the graphene slurry is 0.1 wt.% to 1 wt.%.

[0019] Preferably, the bent surface of the template has a wavy periodic structure, the wavelength of which is 0.1mm~0.2mm and the height is 0.1mm~0.2mm; or, the bent surface of the template includes a flat portion and a plurality of arc-shaped grooves recessed from the flat portion, the width of which is 0.15mm~0.25mm, the depth of which is 0.05mm~0.15mm, and the spacing between adjacent arc-shaped grooves is 0.05mm~0.15mm.

[0020] The graphene film has a thickness of 10 μm to 100 μm and a density of 0.5 g / cm³. 3 ~1.0 g / cm 3 .

[0021] Preferably, the compression rate of the graphene stack is 10% to 80% when compressed;

[0022] And / or, the graphene slurry is applied to the bent surface by spraying.

[0023] Preferably, the adhesive comprises one or more of epoxy resin, phenolic resin, furfural resin, polyurethane, acrylic resin, and silicone; the content of the adhesive in the thermal pad is 10 wt.% to 90 wt.%.

[0024] Preferably, it further includes:

[0025] The graphene stack was compressed and then cured by heating.

[0026] The cured graphene stack is cut along the stacking direction of the graphene film to form a thermally conductive pad of a predetermined thickness.

[0027] Preferably, the curing temperature of the graphene stack is 80℃~180℃, and the holding time is 2h~6h;

[0028] The solidified graphene stack can be cut by wire cutting, laser cutting, blade cutting, cryogenic cutting, or vibration cutting.

[0029] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0030] By preparing a graphene film with a curved structure and compressing the graphene stack along the graphene orientation direction to intensify the curvature of the graphene film, the elasticity of the graphene film in the compression direction can be effectively improved, thereby improving the elasticity of the graphene thermal pad and reducing its compressive modulus. The thermal pad of this application does not require the addition of rigid materials such as high thermal conductivity fibers during preparation, thus not affecting the thermal conductivity of the thermal pad and ensuring a significant reduction in its compressive modulus. Furthermore, the graphene film is prepared and compressed using a template, avoiding the wrinkle deformation or disappearance that occurs with the thermal reduction of wrinkled graphene oxide films, further ensuring a significant reduction in the compressive modulus of the thermal pad. Moreover, the thermal pad of this application does not require shear stress to form a buckled structure in the graphene; the template preparation and compression methods of the graphene stack are simple and controllable, ensuring the formation of a uniform curved structure in the graphene, thereby producing a structurally stable thermal pad. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the template and graphene film structure in an embodiment of the present invention;

[0032] Figure 2 This is a schematic diagram of the template structure according to another embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the structure of the limiting compression fixture and the graphene stack in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the structure of the thermally conductive pad according to an embodiment of the present invention.

[0035] In the figure: 1. Template; 11. Bending surface; 111. Arc groove; 112. Planar part; 2. Graphene film; 21. Graphene stack; 3. Limiting compression fixture; 31. Pressure block; 100. Thermal pad. Detailed Implementation

[0036] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted.

[0037] The terms used to express position and direction in this invention are illustrated with reference to the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this invention.

[0038] Reference Figures 1 to 4The present invention provides a method for preparing a thermally conductive pad, the method comprising steps S01 to S03, and may further include steps S04 and S05.

[0039] Step S01: A template 1 with a tortuous structure is provided. A graphene film 2 is prepared at the tortuous structure of the template 1, and the graphene film 2 forms a curved structure corresponding to the tortuous structure. Specifically, by preparing the graphene film 2 at the tortuous structure, the graphene film 2 adheres to the tortuous structure and forms a curved structure identical to the tortuous structure. Step S01 can be performed multiple times to prepare multiple graphene films 2.

[0040] Step S02: Stack multiple graphene films 2 with curved structures, and use an adhesive to bond and fix adjacent graphene films 2 to form a graphene stack 21.

[0041] Step S03: Compress the graphene stack 21 in a direction that intersects with the stacking direction of the graphene stack 21. Specifically, the stacking direction of the graphene film 2 can be perpendicular to the orientation direction of the graphene, and the compression direction when compressing the graphene stack 21 can be the orientation direction of the graphene.

[0042] Step S04: The graphene stack 21 is compressed and then heated and cured.

[0043] Step S05: Cut the cured graphene stack 21 along the stacking direction of the graphene film 2 to form a thermally conductive pad 100 of a predetermined thickness.

[0044] In step S01, template 1 can be prepared according to the desired curvature and shape of the graphene film 2. The material of template 1 can be metal or ceramic, or it can be a polymer material such as photocurable resin, polyethylene terephthalate, or polystyrene. Template 1 can be formed by 3D printing, or template 1 can be pre-prepared to form a prefabricated structure, and one side of the prefabricated structure can be etched to form a tortuous structure by means of laser etching or other methods.

[0045] The tortuous structure of template 1 is a bent surface 11 located on one side of template 1. (Refer to...) Figure 1 The curved surface 11 of template 1 can be a wave-shaped periodic structure. The wavelength of this wave-shaped periodic structure can be 0.1mm~0.2mm, and the height can be 0.1mm~0.2mm. The wavelength of the wave-shaped periodic structure can be the length of one undulation cycle; multiple undulation cycles are sequentially set to form a wave-shaped periodic structure. The height of the wave-shaped periodic structure can be the vertical interval between the highest and lowest points in one undulation cycle.

[0046] Alternatively, the bent surface 11 of template 1 may not be a wavy periodic structure; for example, refer to... Figure 2 The bent surface 11 of template 1 is a curved surface structure with multiple grooves. Specifically, the bent surface 11 of template 1 includes a horizontal flat portion 112 and multiple arc-shaped grooves 111 recessed from the flat portion 112, with the multiple arc-shaped grooves 111 spaced apart. The width of the arc-shaped groove 111 can be 0.15mm to 0.25mm, the depth of the arc-shaped groove 111 can be 0.05mm to 0.15mm, and the spacing between adjacent arc-shaped grooves 111 can be 0.05mm to 0.15mm. The arc-shaped groove 11 can be a part of a circular groove, for example, the arc-shaped groove 11 is a semi-circular groove.

[0047] The graphene film 2 can be prepared by coating graphene slurry onto the curved surface 11 of the template 1 to form a graphene wet film, drying the graphene wet film, and separating the dried film layer from the template 1 to obtain the graphene film 2. By coating the curved surface of the template 1 to form a graphene wet film, the shape of the graphene wet film can be adapted to the shape of the curved surface, thereby forming a curved structure. After drying, the graphene wet film forms the curved structure graphene film 2. The graphene film 2 can be prepared by methods such as blade coating or spray coating of graphene slurry. Preferably, the graphene film 2 is prepared by spray coating of graphene slurry. Compared with blade coating, the thickness of the graphene film 2 prepared by spray coating can be thinner. The thinner graphene film 2 is easier to bend under pressure, thereby improving the compression performance of the thermal pad 100.

[0048] When spraying graphene slurry onto template 1, to facilitate the separation of the prepared graphene film 2 from template 1, the curved surface 11 of template 1 can be pre-treated. Specifically, a release agent is used to treat the curved surface 11 of template 1 before spraying the graphene slurry onto the treated template 1. By pre-treating the curved surface 11 of template 1 with a release agent, the separation of the prepared graphene film 2 from template 1 can be facilitated.

[0049] Graphene slurry has a certain viscosity; a small amount applied to template 1 does not flow significantly. However, due to the uneven structure of template 1, a larger amount of graphene slurry may deposit towards the depressions. To prevent this deposition, the spraying speed can be controlled, and the graphene wet film can be cured simultaneously with the slurry application. Specifically, the graphene wet film formed on template 1 is heated and cured while the slurry is being sprayed. Therefore, by controlling the spraying speed, the initial sprayed slurry is dried and cured, keeping the amount of flowable graphene slurry on template 1 relatively small. This smaller amount of flowable slurry is then kept non-flowing or essentially non-flowing due to its own viscosity.

[0050] The graphene slurry can be prepared by dissolving a thickener in water to obtain a base liquid, adding graphene microsheets to the base liquid and stirring to disperse them, thereby obtaining the graphene slurry. The thickener can be one or more of sodium carboxymethyl cellulose, hydroxyethyl cellulose, guar gum, and xanthan gum. The thickener increases the viscosity of the graphene slurry, thereby preventing the graphene in the slurry from settling rapidly. The content of the thickener in the graphene slurry can be 0.1 wt.% to 1 wt.%.

[0051] The particle size D50 of the graphene microflakes is <10 μm, and the particle size D max <25μm. Particle size D50 is the particle size value corresponding to a cumulative particle size distribution of 50% for the graphene micro-flake sample. max This represents the largest particle size in graphene microflakes. The graphene content in the graphene slurry ranges from 1 wt.% to 10 wt.%.

[0052] The thickness of the graphene film 2 prepared in step S01 can be 10 μm to 100 μm, and the final density of the graphene film 2 is 0.5 g / cm³. 3 ~1.0g / cm 3 .

[0053] In step S02, the adhesive used to bond and fix the graphene film 2 can be prepared from one or more of epoxy resin, phenolic resin, furfural resin, polyurethane, acrylic resin, and organosilicon. Preferably, the adhesive is organosilicon, which has good flexibility and elasticity and can effectively maintain the physical properties of the thermal pad 100. The content of the adhesive in the thermal pad 100 can be 10 wt.% to 90 wt.%, preferably 20 wt.% to 50 wt.%.

[0054] In the thermal pad 100, the elasticity of the adhesive is better than that of graphene. The compressive modulus of the thermal pad 100 is mainly affected by the graphene film 2. By preparing the graphene film 2 into a bent structure, the bent graphene film 2 forms a spring-like structure, thereby improving the compressive performance of the graphene film 2 and reducing the compressive modulus of the thermal pad 100.

[0055] In step S03, the compression rate of the graphene stack 21 can be 10%~80%, preferably 20%~50%. In step S02, when stacking the graphene film 2, the force acting on the graphene film 2 during stacking causes it to tend towards flatness, thus reducing its curvature. In step S03, by compressing the graphene stack 21, the curvature direction of the graphene film 2 intersects the compression direction, preferably perpendicular to it. During compression, the length of the graphene film 2 decreases and its curvature increases, and the curvature of the compressed graphene film 2 is greater than that of the graphene film 2 prepared in step S01.

[0056] By preparing a graphene film 2 with a curved structure and compressing it to increase its curvature, the elasticity of the graphene film 2 can be effectively improved, thereby improving the elasticity of the graphene thermal pad 100 and reducing its compressive modulus. The thermal pad 100 of this application does not require the addition of rigid materials such as high thermal conductivity fibers during preparation, thus not affecting its thermal conductivity and ensuring a significant reduction in its compressive modulus. Furthermore, the graphene film 2 is prepared and compressed using the template 1, avoiding the wrinkle deformation or disappearance that occurs with the thermal reduction of wrinkled graphene oxide film 2, further ensuring a significant reduction in the compressive modulus of the thermal pad 100. Moreover, the thermal pad 100 of this application does not require shear stress to form a buckled structure in the graphene; the preparation of the template 1 and the compression of the graphene stack 21 are simple and controllable, ensuring the formation of a uniform curved structure in the graphene.

[0057] Reference Figure 3When compressing the graphene stack 21, the graphene stack 21 can be placed inside the limiting compression fixture 3. The limiting compression fixture 3 has a movable pressure block 31 on one side along the graphene orientation direction. The pressure block 31 can move along the graphene orientation direction and press the graphene stack 21 along the orientation direction, so that the graphene stack 21 is compressed along the graphene orientation direction; the amount of compression of the graphene stack 21 can be controlled by controlling the amount of movement of the pressure block 31. When multiple graphene films 2 are stacked to form a graphene stack 21, the number of graphene stacks can be controlled so that the stack thickness of the graphene stack 21 is the same as the width of the internal space of the limiting compression fixture 3. When the graphene stack 21 is installed in the limiting compression fixture 3, the stacking direction of the graphene stack 21 is parallel to the width direction of the limiting compression fixture 3, and the graphene stack 21 can effectively fill the internal space of the limiting compression fixture 3. The stack thickness can remain unchanged when the graphene stack 21 is compressed.

[0058] In step S04, the graphene stack 21 can be cured by heating. The curing temperature of the graphene stack 21 can be 80℃~180℃. That is, when curing the graphene stack 21, the graphene stack 21 is first heated to 80℃~180℃, and then heat preservation curing is performed for 2h~6h.

[0059] In step S05, the cured graphene stack 21 is cut using wire cutting, laser cutting, blade cutting, cryogenic cutting, or vibration cutting. Preferably, wire cutting is used to cut the cured graphene stack 21 along the graphene stacking direction. (Refer to...) Figure 4 After cutting the graphene stack 21, a thermally conductive pad 100 of the required size is obtained.

[0060] The orientation of the graphene described above is the required thermal conductivity direction for the thermal pad 100. In this embodiment, the orientation of the graphene can be vertical. The graphene can be oriented using existing orientation methods, such as magnetic field orientation, extrusion orientation, molding orientation, etc.

[0061] Example 1

[0062] By weight, 2.5 parts guar gum and 2.5 parts sodium carboxymethyl cellulose were dissolved in 945 parts water, and then 50 parts graphene microsheets were added and stirred to disperse the mixture to obtain a graphene slurry. The graphene microsheets had a particle size D50 of 7 μm to 9 μm. High-purity graphene microsheets, such as those with a purity of 99% or higher, were used.

[0063] The curved surface 11 of template 1 adopts a wavy periodic structure with a wavelength of 0.1 mm and a height of 0.1 mm. A release agent is used to treat the curved surface 11 of template 1. Then, a graphene wet film is prepared on the curved surface 11 of template 1 by spraying. During the spraying of the graphene slurry, a hot air gun is used to heat and dry the graphene wet film coated on template 1. After the graphene wet film is completely cured, graphene film 2 is obtained. Graphene film 2 has a thickness of 20 μm and a density of 0.9 g / cm³. 3 The graphene film 2 layers were separated from the template 1. Multiple graphene films 2 were prepared using the same method.

[0064] An adhesive is coated onto the surface of the graphene film 2, and multiple graphene films 2 are stacked along a direction perpendicular to the graphene orientation to form a graphene stack 21. The adhesive is an organosilicon, and the content of the adhesive in the thermal pad 100 is 30 wt.%.

[0065] The graphene stack 21 is placed in the limiting compression fixture 3 and compressed along the graphene orientation direction, with a compression rate of 20%. The graphene stack 21 is heated to 150°C and held at that temperature for 2 hours. After the graphene stack 21 has solidified and formed, it is removed.

[0066] The solidified graphene stack 21 was cut into a 0.3mm thick thermal pad 100 using wire cutting.

[0067] The thermally conductive pad 100 prepared in Example 1 was subjected to performance testing. The thermal conductivity of the thermally conductive pad 100 in the vertical direction was 87 W / (m·K), and the thermal resistance at a pressure of 40 psi was 0.078 K·cm. 2 / W. The stress of a 100mm thermal pad under 50% compression is 47psi.

[0068] Example 2

[0069] By weight, 2.5 parts guar gum and 2.5 parts sodium carboxymethyl cellulose were dissolved in 945 parts water, and then 50 parts graphene microsheets were added and stirred to disperse the mixture to obtain a graphene slurry. The graphene microsheets had a particle size D50 of 7 μm to 9 μm. High-purity graphene microsheets, such as those with a purity of 99% or higher, were used.

[0070] The curved surface 11 of template 1 adopts a wavy periodic structure with a wavelength of 0.1 mm and a height of 0.1 mm. A release agent is used to treat the curved surface 11 of template 1. Then, a graphene wet film is prepared on the curved surface 11 of template 1 by spraying. During the spraying of the graphene slurry, a hot air gun is used to heat and dry the graphene wet film coated on template 1. After the graphene wet film is completely cured, graphene film 2 is obtained. Graphene film 2 has a thickness of 30 μm and a density of 0.8 g / cm³. 3 The graphene film 2 layers were separated from the template 1. Multiple graphene films 2 were prepared using the same method.

[0071] An adhesive is coated onto the surface of the graphene film 2, and multiple graphene films 2 are stacked along a direction perpendicular to the graphene orientation to form a graphene stack 21. The adhesive is an organosilicon, and the content of the adhesive in the thermal pad 100 is 40 wt.%.

[0072] The graphene stack 21 is placed in the limiting compression fixture 3 and compressed along the graphene orientation direction, with a compression rate of 30%. The graphene stack 21 is heated to 120°C and held at that temperature for 2 hours. After the graphene stack 21 has solidified and formed, it is removed.

[0073] The solidified graphene stack 21 was cut into a 0.3mm thick thermal pad 100 using wire cutting.

[0074] The thermally conductive pad 100 prepared in Example 2 was subjected to performance testing. The thermal conductivity of the thermally conductive pad 100 in the vertical direction was 74 W / (m·K), and the thermal resistance at a pressure of 40 psi was 0.088 K·cm. 2 / W. The stress of a 100mm thermal pad under 50% compression is 38psi.

[0075] Example 3

[0076] By weight, 1 part sodium carboxymethyl cellulose was dissolved in 945 parts water, and then 50 parts graphene microsheets were added and stirred to disperse the mixture to obtain a graphene slurry. The particle size D50 of the graphene microsheets was 7 μm to 9 μm. High-purity graphene microsheets, such as those with a purity of 99% or higher, were used.

[0077] The curved surface 11 of template 1 adopts a wavy periodic structure with a wavelength of 0.1 mm and a height of 0.15 mm. A release agent is used to treat the curved surface 11 of template 1. Then, a graphene wet film is prepared on the curved surface 11 of template 1 by spraying. During the spraying of the graphene slurry, a hot air gun is used to heat and dry the graphene wet film coated on template 1. After the graphene wet film is completely cured, graphene film 2 is obtained. Graphene film 2 has a thickness of 50 μm and a density of 0.6 g / cm³. 3 The graphene film 2 layers were separated from the template 1. Multiple graphene films 2 were prepared using the same method.

[0078] An adhesive is sprayed onto the surface of the graphene film 2, and multiple graphene films 2 are stacked along a direction perpendicular to the graphene orientation to form a graphene stack 21. The adhesive is silicone, and its content in the thermal pad 100 is 20 wt.%.

[0079] The graphene stack 21 is placed in the limiting compression fixture 3 and compressed along the graphene orientation direction, with a compression rate of 50%. The graphene stack 21 is heated to 100°C and held at that temperature for 4 hours. After the graphene stack 21 has solidified and formed, it is removed.

[0080] The solidified graphene stack 21 was cut into a 0.3mm thick thermal pad 100 using wire cutting.

[0081] The thermally conductive pad 100 prepared in Example 3 was subjected to performance testing. The thermal conductivity of the thermally conductive pad 100 in the vertical direction was 106 W / (m·K), and the thermal resistance at a pressure of 40 psi was 0.056 K·cm. 2 / W. The stress of a 100mm thermal pad when compressed by 50% is 53 psi.

[0082] Example 4

[0083] By weight, 10 parts of guar gum were dissolved in 940 parts of water, and then 50 parts of graphene microsheets were added and stirred to disperse the mixture to obtain a graphene slurry. The graphene microsheets had a particle size D50 of 7 μm to 9 μm. High-purity graphene microsheets, such as those with a purity of 99% or higher, were used.

[0084] The curved surface 11 of template 1 adopts a wavy periodic structure with a wavelength of 0.2 mm and a height of 0.2 mm. A release agent is used to treat the curved surface 11 of template 1. Then, a graphene wet film is prepared on the curved surface 11 of template 1 by spraying. During the spraying of the graphene slurry, a hot air gun is used to heat and dry the graphene wet film coated on template 1. After the graphene wet film is completely cured, graphene film 2 is obtained. Graphene film 2 has a thickness of 30 μm and a density of 0.8 g / cm³. 3 The graphene film 2 layers were separated from the template 1. Multiple graphene films 2 were prepared using the same method.

[0085] An adhesive is sprayed onto the surface of the graphene film 2, and multiple graphene films 2 are stacked along a direction perpendicular to the graphene orientation to form a graphene stack 21. The adhesive is silicone, and its content in the thermal pad 100 is 50 wt.%.

[0086] The graphene stack 21 is placed in the limiting compression fixture 3 and compressed along the graphene orientation direction, with a compression rate of 20%. The graphene stack 21 is heated to 150°C and held at that temperature for 4 hours. After the graphene stack 21 has solidified and formed, it is removed.

[0087] The solidified graphene stack 21 was cut into a 0.3mm thick thermal pad 100 using wire cutting.

[0088] The thermally conductive pad 100 prepared in Example 4 was subjected to performance testing. The thermal conductivity of the thermally conductive pad 100 in the vertical direction was 68 W / (m·K), and the thermal resistance at a pressure of 40 psi was 0.097 K·cm. 2 / W. The stress of a 100mm thermal pad when compressed by 50% is 32psi.

[0089] Example 5

[0090] By weight, 5 parts of sodium carboxymethyl cellulose were dissolved in 945 parts of water, and then 50 parts of graphene microsheets were added and stirred to disperse the mixture to obtain a graphene slurry. The particle size D50 of the graphene microsheets was 7 μm to 9 μm. High-purity graphene microsheets, such as those with a purity of 99% or higher, were used.

[0091] The curved surface 11 of template 1 adopts a wavy periodic structure with a wavelength of 0.1 mm and a height of 0.1 mm. A release agent is used to treat the curved surface 11 of template 1, and then a graphene wet film is prepared on the curved surface 11 of template 1 by spraying. A hot air gun is used to heat and dry the graphene wet film coated on template 1 during the spraying of the graphene slurry. The graphene film 2 has a thickness of 30 μm and a density of 0.8 g / cm³.3 The graphene film 2 layers were separated from the template 1. Multiple graphene films 2 were prepared using the same method.

[0092] After impregnating the graphene film 2 with an adhesive, multiple graphene films 2 are stacked along a direction perpendicular to the graphene orientation to form a graphene stack 21. The adhesive is an organosilicon, and the content of the adhesive in the thermal pad 100 is 30 wt.%.

[0093] The graphene stack 21 is placed in the limiting compression fixture 3 and compressed along the graphene orientation direction, with a compression rate of 20%. The graphene stack 21 is heated to 150°C and held at that temperature for 6 hours. After the graphene stack 21 has solidified and formed, it is removed.

[0094] The solidified graphene stack 21 was cut into a 0.3mm thick thermal pad 100 using wire cutting.

[0095] The thermally conductive pad 100 prepared in Example 5 was subjected to performance testing. The thermal conductivity of the thermally conductive pad 100 in the vertical direction was 94 W / (m·K), and the thermal resistance at a pressure of 40 psi was 0.072 K·cm. 2 / W. The stress of a 100mm thermal pad when compressed by 50% is 53 psi.

[0096] Example 6

[0097] By weight, 5 parts guar gum were dissolved in 945 parts water, and then 50 parts graphene microsheets were added and stirred to disperse the mixture to obtain a graphene slurry. The graphene microsheets had a particle size D50 of 7 μm to 9 μm. High-purity graphene microsheets, such as those with a purity of 99% or higher, were used.

[0098] The bent surface 11 of template 1 is a curved surface structure with multiple arc-shaped grooves 111. The width of each arc-shaped groove 111 is 0.2 mm, the depth of each groove is 0.1 mm, and the spacing between adjacent arc-shaped grooves 111 is 0.1 mm. A release agent is used to treat the bent surface 11 of template 1. Then, a graphene wet film is prepared on the bent surface 11 of template 1 by spraying. During the spraying of the graphene slurry, a hot air gun is used to heat and dry the graphene wet film coated on template 1. After the graphene wet film is completely cured, graphene film 2 is obtained. Graphene film 2 has a thickness of 20 μm and a density of 0.9 g / cm³. 3 The graphene film 2 layers were separated from the template 1. Multiple graphene films 2 were prepared using the same method.

[0099] An adhesive is coated onto the surface of the graphene film 2, and multiple graphene films 2 are stacked along a direction perpendicular to the graphene orientation to form a graphene stack 21. The adhesive is an organosilicon, and the content of the adhesive in the thermal pad 100 is 30 wt.%.

[0100] The graphene stack 21 is placed in the limiting compression fixture 3 and compressed along the graphene orientation direction, with a compression rate of 20%. The graphene stack 21 is heated to 150°C and held at that temperature for 2 hours. After the graphene stack 21 has solidified and formed, it is removed.

[0101] The solidified graphene stack 21 was cut into a 0.3mm thick thermal pad 100 using wire cutting.

[0102] The thermally conductive pad 100 prepared in Example 5 was subjected to performance testing. The thermal conductivity of the thermally conductive pad 100 in the vertical direction was 81 W / (m·K), and the thermal resistance at a pressure of 40 psi was 0.086 K·cm. 2 / W. The stress of a 100mm thermal pad under 50% compression is 57psi.

[0103] In summary, the thermal pad 100 prepared using the method of this application has a thermal conductivity of over 68 W / (m·K) along the orientation direction (perpendicular direction), and the thermal conductivity of the thermal pad 100 can reach 100 W / (m·K), which is excellent. Furthermore, the thermal resistance of the thermal pad 100 at a pressure of 40 psi is less than 0.1 K·cm. 2 With a low thermal resistance ( / W), the thermal pad 100 exhibits superior thermal conductivity. The thermal pad 100 experiences less than 57 psi under 50% compression, indicating low compressive stress. Therefore, the thermal pad 100 prepared in this application possesses both excellent thermal conductivity and physical properties.

[0104] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the invention without departing from the principles and spirit of the invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a thermally conductive pad, characterized in that, include: A template with a tortuous structure is provided, and a graphene film is prepared at the tortuous structure of the template, wherein the graphene film forms a curved structure corresponding to the tortuous structure; Multiple graphene films with curved structures are stacked and adjacent graphene films are bonded together with an adhesive to form a graphene stack. The graphene stack is compressed in a direction that intersects with the stacking direction of the graphene stack.

2. The method for preparing the thermally conductive pad according to claim 1, characterized in that, The compression direction when the graphene stack is compressed is the orientation direction of the graphene in the thermal pad. And / or, the stacking direction of the plurality of graphene films is perpendicular to the orientation direction of the graphene in the thermal pad, and the bending direction of the graphene films is parallel to the stacking direction of the plurality of graphene films.

3. The method for preparing the thermally conductive pad according to claim 1, characterized in that, One side of the template is provided with a curved surface. Graphene slurry is coated on the curved surface to form a graphene wet film. The graphene wet film is dried and the dried film layer is separated from the template to obtain the graphene film.

4. The method for preparing the thermally conductive pad according to claim 3, characterized in that, The graphene slurry is prepared by the following steps: a thickener is added to water to dissolve and obtain a base liquid, graphene microsheets are added to the base liquid and stirred and dispersed to obtain the graphene slurry; The graphene content in the graphene slurry is 1 wt.% to 10 wt.%.

5. The method for preparing the thermally conductive pad according to claim 4, characterized in that, The particle size D50 of the graphene microflakes is <10 μm, and the particle size D max <25μm; And / or, the thickener is one or more of sodium carboxymethyl cellulose, hydroxyethyl cellulose, guar gum, and xanthan gum, and the content of the thickener in the graphene slurry is 0.1 wt.% to 1 wt.%.

6. The method for preparing the thermally conductive pad according to claim 3, characterized in that, The bending surface of the template has a wavy periodic structure with a wavelength of 0.1mm to 0.2mm and a height of 0.1mm to 0.2mm; or, the bending surface of the template includes a flat portion and a plurality of arc-shaped grooves recessed from the flat portion, the width of the arc-shaped grooves being 0.15mm to 0.25mm, the depth of the arc-shaped grooves being 0.05mm to 0.15mm, and the spacing between adjacent arc-shaped grooves being 0.05mm to 0.15mm. The graphene film has a thickness of 10 μm to 100 μm and a density of 0.5 g / cm³. 3 ~1.0 g / cm 3 .

7. The method for preparing the thermally conductive pad according to claim 3, characterized in that, The compression rate of the graphene stack is 10% to 80% when compressed. And / or, the graphene slurry is applied to the bent surface by spraying.

8. The method for preparing a thermally conductive pad according to claim 1, characterized in that, The adhesive includes one or more of epoxy resin, phenolic resin, furfural resin, polyurethane, acrylic resin, and silicone; the content of the adhesive in the thermal pad is 10 wt.% to 90 wt.%.

9. The method for preparing a thermally conductive pad according to claim 1, characterized in that, Also includes: The graphene stack was compressed and then cured by heating. The cured graphene stack is cut along the stacking direction of the graphene film to form a thermally conductive pad of a predetermined thickness.

10. The method for preparing a thermally conductive pad according to claim 9, characterized in that, The curing temperature of the graphene stack is 80℃~180℃, and the holding time is 2h~6h. The solidified graphene stack can be cut by wire cutting, laser cutting, blade cutting, cryogenic cutting, or vibration cutting.

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