Heat-conducting graphene sheet and preparation method therefor

Abstract

The present invention belongs to the field of graphene, and particularly relates to a heat-conducting graphene sheet and a preparation method therefor. The heat-conducting graphene sheet provided in the present invention is prepared by subjecting a heat-conducting graphene sheet semi-finished product to hot-pressing, wherein the heat-conducting graphene sheet semi-finished product comprises a glass fiber sheet and graphene microchip sizing material layers compounded on both sides of the surfaces of the glass fiber sheet, with the components of the graphene microchip sizing material layer comprise organic silicon surface-modified graphene microchips, boron nitride and an organic silicon glue. The heat-conducting graphene sheet provided in the present invention has relatively good toughness, a smooth and flat surface and both good in-plane heat-conducting property and good vertical heat-conducting property, and has wide application prospects in the application fields of heat management, electronic device heat dissipation, new energy, etc.

Description

A thermally conductive graphene sheet and its preparation method Technical Field

[0001] This invention belongs to the field of graphene, and particularly relates to a thermally conductive graphene sheet and its preparation method. Background Technology

[0002] Graphene is a two-dimensional crystalline structure composed of carbon atoms with excellent thermal conductivity. However, conventional graphene sheets present some challenges in certain applications. First, conventional graphene sheets have poor flexibility, making them prone to cracking during bending, which affects their assembly performance. Second, the rough surface of conventional graphene sheets results in high contact thermal resistance. Finally, while conventional graphene sheets have high in-plane thermal conductivity, their vertical thermal conductivity is poor, limiting their effectiveness in some vertical heat conduction applications.

[0003] Therefore, it is essential to develop a new type of thermally conductive graphene sheet to address the problems of poor toughness, rough surface, and poor vertical thermal conductivity of conventional graphene sheets in existing technologies. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a thermally conductive graphene sheet and its preparation method. The thermally conductive graphene sheet provided by the present invention has good toughness, a smooth and flat surface, and excellent in-plane thermal conductivity and vertical thermal conductivity.

[0005] This invention provides a thermally conductive graphene sheet, which is made by hot pressing a semi-finished thermally conductive graphene sheet. The semi-finished thermally conductive graphene sheet includes a glass fiber sheet and a graphene micro-flake adhesive layer laminated on both sides of the glass fiber sheet. The graphene micro-flake adhesive layer comprises organosilicon surface-modified graphene micro-flakes, boron nitride, and organosilicon water.

[0006] Preferably, the graphene micro-flakes in the organosilicon surface-modified graphene micro-flakes have a particle size (equivalent diameter) of 30–100 μm.

[0007] Preferably, the boron nitride has a particle size of 30–100 μm.

[0008] Preferably, the mass ratio of the organosilicon surface-modified graphene microsheets, boron nitride, and organosilicon water is 80:(5-30):(20-80).

[0009] Preferably, the thickness of the glass fiber sheet is 10-50 μm; the thickness of the graphene microfiber adhesive layer on one side of the glass fiber sheet is 50-200 μm.

[0010] This invention provides a method for preparing the thermally conductive graphene sheet described above, comprising the following steps:

[0011] a) Mix organosilicon-modified graphene microsheets, boron nitride, organosilicon water, and solvent to obtain graphene microsheet adhesive;

[0012] b) The graphene microsheet adhesive is coated on both sides of the glass fiber sheet and dried to obtain a semi-finished product of thermally conductive graphene sheet.

[0013] c) The thermally conductive graphene sheet semi-finished product is hot-pressed to obtain a thermally conductive graphene sheet.

[0014] Preferably, in step a), the organosilicon surface-modified graphene microsheets are prepared according to the following steps: the graphene microsheet raw material is immersed in an organosilicon modifier, taken out and dried to obtain organosilicon surface-modified graphene microsheets.

[0015] Preferably, the graphene micro-sheet raw material is prepared according to the following steps: acid washing of graphite powder to obtain graphene micro-sheet raw material.

[0016] Preferably, in step a), the specific mixing process includes: first mixing the silicone-modified graphene microsheets with a solvent to obtain a graphene microsheet slurry; then mixing the graphene microsheet slurry, boron nitride, and silicone water to obtain a graphene microsheet adhesive.

[0017] Preferably, in step c), the pressure of the hot pressing is 5-15 MPa; the temperature of the hot pressing is 140-180°C.

[0018] Compared with existing technologies, this invention provides a thermally conductive graphene sheet and its preparation method. The thermally conductive graphene sheet provided by this invention is made by hot pressing a semi-finished thermally conductive graphene sheet. The semi-finished thermally conductive graphene sheet includes a glass fiber sheet and a graphene micro-flake adhesive layer laminated on both sides of the glass fiber sheet. The graphene micro-flake adhesive layer comprises organosilicon surface-modified graphene micro-flakes, boron nitride, and organosilicon water. This invention improves the toughness of thermally conductive graphene sheets by modifying the surface of graphene microsheets with organosilicon, increasing their wettability and fillability. By filling the gaps between graphene microsheet powder particles with boron nitride, the interlayer structure of the graphene microsheets is optimized, resulting in a smooth and flat surface on the formed sheet and increasing the longitudinal thermal conductivity channels, thus improving the vertical thermal conductivity. Furthermore, by sandwiching glass fiber sheets as reinforcing layers between the thermally conductive graphene sheets, the toughness and strength of the sheet are further enhanced. Finally, by using hot pressing to composite the semi-finished materials, a dense whole is formed, optimizing the internal structure of the sheet, reducing interlayer resistance, and further increasing the thermal conductivity. The thermally conductive graphene sheet provided by this invention has good toughness, a smooth and flat surface, and excellent in-plane and vertical thermal conductivity, showing broad application prospects in thermal management, electronic device heat dissipation, and new energy fields. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides a thermally conductive graphene sheet, which is made by hot pressing a semi-finished thermally conductive graphene sheet. The semi-finished thermally conductive graphene sheet includes a glass fiber sheet and a graphene micro-flake adhesive layer laminated on both sides of the glass fiber sheet. The graphene micro-flake adhesive layer comprises organosilicon surface-modified graphene micro-flakes, boron nitride, and organosilicon water.

[0021] In the thermally conductive graphene sheet provided by the present invention, the thickness of the glass fiber sheet is preferably 10 to 50 μm, specifically 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm.

[0022] In the thermally conductive graphene sheet provided by this invention, the organosilicon surface-modified graphene microsheets in the graphene microsheet adhesive layer are preferably prepared according to the following steps: immersing the graphene microsheet raw material in an organosilicon modifier, removing and drying it to obtain organosilicon surface-modified graphene microsheets. The particle size of the graphene microsheet raw material is preferably 30–100 μm, specifically 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm; the immersion temperature is preferably 10–40℃, specifically 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, or 40℃; the immersion time is preferably 10–60 min, specifically 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min.

[0023] In the thermally conductive graphene sheet provided by the present invention, the particle size of boron nitride in the graphene microsheet adhesive layer is preferably 30-100 μm, specifically 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0024] In the thermally conductive graphene sheet provided by this invention, the preferred mass ratio of the silicone-modified graphene micro-sheets, boron nitride, and silicone water in the graphene micro-sheet adhesive layer is 80:(5-30):(20-80). Specifically, the mass ratio of the silicone-modified graphene micro-sheets to boron nitride can be 80:5, 80:6, 80:7, 80:8, 80:9, 80:10, 80:11, 80:12, 80:13, 80:14, 80:15, 80:16, 80:17, or 80:1. 8, 80:19, 80:20, 80:21, 80:22, 80:23, 80:24, 80:25, 80:26, 80:27, 80:28, 80:29 or 80:30; the specific mass ratio of the organosilicon surface-modified graphene micro-flakes to organosilicon water can be 80:20, 80:25, 80:30, 80:35, 80:40, 80:45, 80:50, 80:55, 80:60, 80:65, 80:70, 80:75 or 80:80.

[0025] In the thermally conductive graphene sheet provided by the present invention, the thickness of one side of the graphene microsheet adhesive layer is preferably 50-200 μm, specifically 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm or 200 μm.

[0026] In the thermally conductive graphene sheet provided by the present invention, the hot-pressing pressure is preferably 5-15 MPa, specifically 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa or 15 MPa; the hot-pressing temperature is preferably 140-180℃, specifically 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃ or 180℃; the hot-pressing time is preferably 30-180s, specifically 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s, 130s, 140s, 150s, 160s, 170s or 180s.

[0027] This invention also provides a method for preparing the thermally conductive graphene sheet described above, comprising the following steps:

[0028] a) Mix organosilicon-modified graphene microsheets, boron nitride, organosilicon water, and solvent to obtain graphene microsheet adhesive;

[0029] b) The graphene microsheet adhesive is coated on both sides of the glass fiber sheet and dried to obtain a semi-finished product of thermally conductive graphene sheet.

[0030] c) The thermally conductive graphene sheet semi-finished product is hot-pressed to obtain a thermally conductive graphene sheet.

[0031] In the preparation method provided by this invention, in step a), the organosilicon surface-modified graphene microsheets are preferably prepared according to the following steps: immersing graphene microsheet raw materials in an organosilicon modifier, removing and drying them to obtain organosilicon surface-modified graphene microsheets. The particle size of the graphene microsheet raw materials is preferably 30–100 μm, specifically 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm; the immersion temperature is preferably 10–40℃, specifically 10℃, 15℃, 20℃, 25℃, 30℃, 35℃, or 40℃; the immersion time is preferably 10–60 min, specifically 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min.

[0032] In the preparation method provided by this invention, the graphene micro-flake raw material is preferably prepared according to the following steps: acid washing of graphite powder to obtain graphene micro-flake raw material. In this invention, it is preferable to screen the acid-washed graphene micro-flake raw material to obtain graphene micro-flake raw material of the required size.

[0033] In the preparation method provided by the present invention, in step a), the particle size of the boron nitride is preferably 30-100 μm, specifically 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm or 100 μm.

[0034] In the preparation method provided by this invention, in step a), the preferred mass ratio of the organosilicon surface-modified graphene microsheets, boron nitride, and organosilicon water is 80:(5-30):(20-80). Specifically, the mass ratio of the organosilicon surface-modified graphene microsheets to boron nitride can be 80:5, 80:6, 80:7, 80:8, 80:9, 80:10, 80:11, 80:12, 80:13, 80:14, 80:15, 80:16, 80:17, 80:18, 80:1 ... The mass ratio of the organosilicon-modified graphene micro-flakes to the organosilicon water can be 0:19, 80:20, 80:21, 80:22, 80:23, 80:24, 80:25, 80:26, 80:27, 80:28, 80:29, or 80:30; specifically, the mass ratio of the organosilicon-modified graphene micro-flakes to the organosilicon water can be 80:20, 80:25, 80:30, 80:35, 80:40, 80:45, 80:50, 80:55, 80:60, 80:65, 80:70, 80:75, or 80:80.

[0035] In the preparation method provided by the present invention, in step a), there is no particular limitation on the type and amount of the solvent. The organosilicon surface-modified graphene microsheets, boron nitride and organosilicon water can be uniformly mixed and dispersed. Benzene-based solvents are preferred.

[0036] In the preparation method provided by the present invention, in step a), the mixing temperature is preferably 10-40℃, more preferably 25℃ (room temperature); the specific mixing process preferably includes: a1) first mixing organosilicon surface-modified graphene microsheets and solvent to obtain graphene microsheet slurry; a2) then mixing the graphene microsheet slurry, boron nitride and organosilicon water to obtain graphene microsheet adhesive. In step a1), the mixing method is preferably to first perform ultrasonic mixing, then stirring mixing, and finally continuing ultrasonic mixing. The first ultrasonic mixing time is preferably 10-15 min, the stirring mixing time is preferably 30-40 min, and the second ultrasonic mixing time is preferably 10-15 min. In step a2), the mixing method is preferably to first perform ultrasonic mixing, then stirring mixing, and finally continuing ultrasonic mixing. The first ultrasonic mixing time is preferably 10-15 min, the stirring mixing time is preferably 30-40 min, and the second ultrasonic mixing time is preferably 10-15 min.

[0037] In the preparation method provided by the present invention, in step b), the thickness of the glass fiber sheet is preferably 10-50 μm, specifically 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm.

[0038] In the preparation method provided by the present invention, in step b), the coating method is preferably blade coating; the thickness of the graphene microfiber adhesive on one side of the glass fiber sheet is preferably 50-200 μm, specifically 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm or 200 μm.

[0039] In the preparation method provided by the present invention, in step c), the pressure of the hot pressing is preferably 5-15 MPa, specifically 5 MPa, 6 MPa, 7 MPa, 8 MPa, 9 MPa, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa or 15 MPa; the temperature of the hot pressing is preferably 140-180℃, specifically 140℃, 145℃, 150℃, 155℃, 160℃, 165℃, 170℃, 175℃ or 180℃; the time of the hot pressing is preferably 30-180s, specifically 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s, 130s, 140s, 150s, 160s, 170s or 180s.

[0040] The technical solution provided by this invention modifies the surface of graphene microsheets with organosilicon to increase the wettability and fillability of the graphene microsheets, thereby improving the toughness of the thermally conductive graphene sheets. By filling the gaps between the graphene microsheet powder with boron nitride, the interlayer structure of the graphene microsheets is optimized, which not only makes the surface of the formed sheet smooth and flat, but also increases the longitudinal thermal conduction channels of the material, thereby improving the vertical thermal conductivity of the graphene sheets. By sandwiching glass fiber sheets as reinforcing layers between the thermally conductive graphene sheets, the toughness and strength of the sheets are further improved. By using hot pressing to composite the semi-finished materials, they are bonded into a dense whole, optimizing the internal structure of the sheets, reducing interlayer resistance, and further increasing the thermal conductivity of the sheets.

[0041] The technical solution provided by this invention has at least the following beneficial effects:

[0042] 1) High thermal conductivity: Compared with conventional graphene sheets, the graphene sheets of the present invention can conduct heat more quickly and efficiently.

[0043] 2) Improved toughness: Conventional graphene sheets have poor toughness and are prone to cracking, which affects assembly; while the thermally conductive graphene sheet of this invention can effectively improve the toughness problem, increase its bending and assembly reliability, and better adapt to various stress environments, thereby improving its service life and reliability.

[0044] 3) Low thermal resistance: Conventional graphene sheets have rough surfaces, requiring the use of silicone grease or similar materials to reduce contact thermal resistance; however, the graphene sheets of this invention have smooth and flat surfaces, resulting in lower contact thermal resistance, less resistance encountered during heat conduction, and higher thermal conductivity.

[0045] 4) Solving the problem of poor vertical thermal conductivity: Conventional graphene sheets do not have uniform thermal conductivity in the vertical direction, resulting in poor overall vertical thermal conductivity; however, this invention optimizes the material structure and thermal conduction path, so that the graphene sheet has more uniform thermal conductivity in the vertical direction.

[0046] In summary, compared with the prior art, the thermally conductive graphene sheet of the present invention has advantages such as higher thermal conductivity, lower thermal resistance, better toughness, and more uniform vertical thermal conductivity.

[0047] Based on the superior effects achievable by the technical solution of this invention, the technical solution of this invention can be widely applied in fields such as thermal management, heat dissipation of electronic devices, and new energy. More specifically:

[0048] Firstly, in the field of thermal management, thermally conductive graphene sheets with high thermal conductivity and low thermal resistance can be used to manufacture efficient heat dissipation devices. Nowadays, the integration of various electronic devices is constantly increasing, leading to concentrated heat release. However, the poor toughness and high contact thermal resistance of conventional graphene sheets limit the performance of heat dissipation devices. The thermally conductive graphene sheets prepared using the technical solution of this invention can effectively improve these problems, providing better thermal conductivity, thereby improving the efficiency and reliability of heat dissipation devices.

[0049] Secondly, in the field of heat dissipation for electronic devices, thermally conductive graphene sheets with high thermal conductivity and low thermal resistance can be used to manufacture high-performance heat sinks, thermally conductive films, and other heat dissipation materials. With the continuous increase in the power of electronic devices, heat dissipation problems are becoming increasingly prominent. The technical solution of this invention can effectively improve the thermal conductivity of thermally conductive graphene sheets, making them ideal heat dissipation materials that can effectively reduce the temperature of electronic devices and improve their stability and lifespan.

[0050] Furthermore, in the field of new energy, thermally conductive graphene sheets with high thermal conductivity and low thermal resistance can be applied to photovoltaic cells, electric vehicle batteries, and other fields. Photovoltaic cells and electric vehicle batteries generate a large amount of heat during operation; if this heat cannot be dissipated in time, it can lead to reduced efficiency and safety hazards. The technical solution of this invention can provide highly efficient thermal conductivity, helping photovoltaic cells and electric vehicle batteries to dissipate heat in a timely manner, thereby improving their energy conversion efficiency and safety.

[0051] For clarity, the following examples and comparative examples will be used to provide a detailed description.

[0052] Comparative Example 1

[0053] Step 1: Acid wash the graphite powder with a purity of 99% or higher to obtain graphene micro-flake raw material with a purity of 99% or higher; screen the graphene micro-flake raw material to obtain 60μm graphene micro-flake raw material.

[0054] Step 2: The obtained graphene micro-flake raw materials are cleaned and then soaked in an organosilicon modifier at a temperature of 25°C for about 30 minutes. During the soaking, the surface of the graphene micro-flakes is modified by π-π conjugation. After soaking, the micro-flakes are screened and dried to obtain modified graphene micro-flakes with increased toughness and filling capacity.

[0055] Step 3: Accurately weigh 80 parts by mass of the modified graphene micro flakes and add them to a benzene-based solvent. Sonicate at room temperature for 10 minutes, stir and disperse for 30 minutes, and then sonicate again for 10 minutes to obtain a uniform graphene micro flake slurry.

[0056] Step 4: Accurately weigh 15 parts by mass of silicone water (polydimethylsiloxane containing vinyl groups) and add it to the above graphene micro-flake slurry. Sonicate at room temperature for 10 minutes, stir and disperse for 30 minutes, and then sonicate and disperse for another 10 minutes to ensure that the silicone water is evenly distributed throughout the graphene micro-flake slurry, thus obtaining the graphene micro-flake adhesive.

[0057] Step 5: Using a 20μm thick glass fiber sheet as a carrier, the prepared graphene micro-sheet adhesive is coated onto both sides of the glass fiber and baked dry to obtain a semi-finished product with a thickness of approximately 400μm.

[0058] Step 6: The above semi-finished product is hot-pressed at 150-160℃ and 10MPa for 90s to obtain thermally conductive graphene sheets.

[0059] Example 1

[0060] Step 1: Acid wash the graphite powder with a purity of 99% or higher to obtain graphene micro-flake raw material with a purity of 99% or higher; screen the graphene micro-flake raw material to obtain 60μm graphene micro-flake raw material.

[0061] Step 2: The obtained graphene micro-flake raw materials are cleaned and then soaked in an organosilicon modifier at a temperature of 25°C for about 30 minutes. During the soaking, the surface of the graphene micro-flakes is modified by π-π conjugation. After soaking, the micro-flakes are screened and dried to obtain modified graphene micro-flakes with increased toughness and filling capacity.

[0062] Step 3: Accurately weigh 80 parts by mass of the modified graphene micro flakes and add them to a benzene-based solvent. Sonicate at room temperature for 10 minutes, stir and disperse for 30 minutes, and then sonicate again for 10 minutes to obtain a uniform graphene micro flake slurry.

[0063] Step 4: Accurately weigh 20 parts by mass of boron nitride with a particle size of 60 μm and 15 parts by mass of silicone water (polydimethylsiloxane containing vinyl groups) and add them to the above graphene micro-sheet slurry. Sonicate at room temperature for 10 min, stir and disperse for 30 min, and then sonicate and disperse for another 10 min to ensure that the boron nitride and silicone water are evenly distributed throughout the thermally conductive graphene micro-sheet slurry, thus obtaining the graphene micro-sheet adhesive.

[0064] Step 5: Using a 20μm thick glass fiber sheet as a carrier, the prepared graphene micro-sheet adhesive is coated onto both sides of the glass fiber and baked dry to obtain a semi-finished product with a thickness of approximately 400μm.

[0065] Step 6: The above semi-finished product is hot-pressed at 150-160℃ and 10MPa for 90s to obtain thermally conductive graphene sheets.

[0066] Example 2

[0067] Step 1: Acid wash the graphite powder with a purity of 99% or higher to obtain graphene micro-flake raw material with a purity of 99% or higher; screen the graphene micro-flake raw material to obtain 60μm graphene micro-flake raw material.

[0068] Step 2: The obtained graphene micro-flake raw materials are cleaned and then soaked in an organosilicon modifier at a temperature of 25°C for about 30 minutes. During the soaking, the surface of the graphene micro-flakes is modified by π-π conjugation. After soaking, the micro-flakes are screened and dried to obtain modified graphene micro-flakes with increased toughness and filling capacity.

[0069] Step 3: Accurately weigh 80 parts by mass of the modified graphene micro flakes and add them to a benzene-based solvent. Sonicate at room temperature for 10 minutes, stir and disperse for 30 minutes, and then sonicate again for 10 minutes to obtain a uniform graphene micro flake slurry.

[0070] Step 4: Accurately weigh 40 parts by mass of boron nitride with a particle size of 60 μm and 15 parts by mass of silicone water (polydimethylsiloxane containing vinyl groups) and add them to the above graphene micro-sheet slurry. Sonicate at room temperature for 10 min, stir and disperse for 30 min, and then sonicate and disperse for another 10 min to ensure that the boron nitride and silicone water are evenly distributed throughout the thermally conductive graphene micro-sheet slurry, thus obtaining the graphene micro-sheet adhesive.

[0071] Step 5: Using a 20μm thick glass fiber sheet as a carrier, the prepared graphene micro-sheet adhesive is coated onto both sides of the glass fiber and baked dry to obtain a semi-finished product with a thickness of approximately 400μm.

[0072] Step 6: The above semi-finished product is hot-pressed at 150-160℃ and 10MPa for 90s to obtain thermally conductive graphene sheets.

[0073] Example 3

[0074] Step 1: Acid wash the graphite powder with a purity of 99% or higher to obtain graphene micro-flake raw material with a purity of 99% or higher; screen the graphene micro-flake raw material to obtain 60μm graphene micro-flake raw material.

[0075] Step 2: The obtained graphene micro-flake raw materials are cleaned and then soaked in an organosilicon modifier at a temperature of 25°C for about 30 minutes. During the soaking, the surface of the graphene micro-flakes is modified by π-π conjugation. After soaking, the micro-flakes are screened and dried to obtain modified graphene micro-flakes with increased toughness and filling capacity.

[0076] Step 3: Accurately weigh 80 parts by mass of the modified graphene micro flakes and add them to a benzene-based solvent. Sonicate at room temperature for 10 minutes, stir and disperse for 30 minutes, and then sonicate again for 10 minutes to obtain a uniform graphene micro flake slurry.

[0077] Step 4: Accurately weigh 80 parts by mass of boron nitride with a particle size of 60 μm and 15 parts by mass of silicone water (polydimethylsiloxane containing vinyl groups) and add them to the above graphene micro-sheet slurry. Sonicate at room temperature for 10 min, stir and disperse for 30 min, and then sonicate and disperse for another 10 min to ensure that the boron nitride and silicone water are evenly distributed throughout the thermally conductive graphene micro-sheet slurry, thus obtaining the graphene micro-sheet adhesive.

[0078] Step 5: Using a 20μm thick glass fiber sheet as a carrier, the prepared graphene micro-sheet adhesive is coated onto both sides of the glass fiber and baked dry to obtain a semi-finished product with a thickness of approximately 400μm.

[0079] Step 6: The above semi-finished product is hot-pressed at 150-160℃ and 10MPa for 90s to obtain thermally conductive graphene sheets.

[0080] Performance Evaluation

[0081] The composition of the graphene microsheet adhesive used in Comparative Example 1 and Examples 1-3 is summarized in Table 1, and the performance test results of the products are summarized in Table 2.

[0082] Table 1. Graphene microsheet adhesive composition

[0083] Table 2 Performance Test Results

[0084] As can be seen from Table 2, the preparation method used in the embodiments of the present invention can improve the problems of poor toughness, high contact thermal resistance, and poor vertical thermal conductivity of conventional graphene sheets.

[0085] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A thermally conductive graphene sheet, characterized by, The heat-conducting graphite sheet is made by hot pressing of a heat-conducting graphite sheet semi-product, which comprises glass fiber sheets and graphite microsheet glue layers compounded on both sides of the glass fiber sheets, and the components of the graphite microsheet glue layers include organosilicon surface-modified graphite microsheets, boron nitride and organosilicon glue; the thickness of the glass fiber sheets is 10-50 microns, the thickness of the graphite microsheet glue layers on one side of the glass fiber sheets is 50-200 microns; the pressure of the hot pressing is 5-15 MPa, and the temperature of the hot pressing is 140-180 degrees Celsius.

2. The thermally conductive graphene sheet of claim 1, wherein, The particle size of the graphite microsheets in the organosilicon surface-modified graphite microsheets is 30-100 microns.

3. The thermally conductive graphene sheet of claim 1, wherein, The particle size of the boron nitride is 30-100 microns.

4. The thermally conductive graphene sheet of claim 1, wherein, The mass ratio of the organosilicon surface-modified graphite microsheets, boron nitride and organosilicon glue is 80:(5-30):(20-80).

5. A method of producing the thermally conductive graphene sheet according to any one of claims 1 to 4, characterized by, The method comprises the following steps: a) mixing organosilicon surface-modified graphite microsheets, boron nitride, organosilicon glue and a solvent to obtain graphite microsheet glue; b) coating the graphite microsheet glue on both sides of the glass fiber sheets and drying to obtain the heat-conducting graphite sheet semi-product; c) hot pressing the heat-conducting graphite sheet semi-product to obtain the heat-conducting graphite sheet.

6. The production method according to claim 5, wherein In step a), the organosilicon surface-modified graphite microsheets are prepared by the following steps: soaking graphite microsheet raw materials in an organosilicon modifier, taking them out and drying to obtain organosilicon surface-modified graphite microsheets.

7. The production method according to claim 6, characterized by, The graphite microsheet raw materials are prepared by the following steps: acid washing graphite powder to obtain graphite microsheet raw materials.

8. The preparation method according to claim 5, characterized in that, In step a), the specific process of the mixing includes: first mixing organosilicon surface-modified graphite microsheets and a solvent to obtain graphite microsheet slurry; then mixing the graphite microsheet slurry, boron nitride and organosilicon glue to obtain graphite microsheet glue.

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