High-thermal-conductivity graphene film and preparation method thereof

Abstract

The invention relates to the technical field of graphene films, in particular to a high-thermal-conductivity graphene film and a preparation method thereof.According to the high-thermal-conductivity graphene film and the preparation method thereof, through surface modification of boron nitride nanopowder and introduction of active hydroxyl groups to the surface of the boron nitride nanopowder, the interface bonding force of boron nitride and a polyimide matrix can be enhanced, and an efficient heat conduction path is formed; through cooperation with synergistic dispersion of calcium carbonate whiskers, a three-dimensional heat-conducting network can be constructed in a polyimide matrix, so that the heat conductivity of the graphene film is improved; the inorganic particle dispersion liquid is subjected to surface modification by adopting a silane coupling agent KH-550, high-speed shearing and glass bead grinding are combined, and uniform dispersion of nano particles can be realized, so that performance fluctuation caused by agglomeration is avoided, the bubble defect is eliminated through defoaming treatment, and the film forming uniformity can be ensured; the polyimide film is subjected to stepped heating curing, the internal stress can be effectively reduced, cracks are avoided, the graphite microcrystal orientation can be further optimized through carbonization and graphitization treatment, and the film material has the performance of high heat conductivity and high mechanical strength.

Description

Technical Field

[0001] This invention relates to the field of graphene film technology, specifically to a high thermal conductivity graphene film and its preparation method. Background Technology

[0002] With the rapid development of 5G communication, new energy vehicles, aerospace and other fields, the performance requirements for high thermal conductivity materials are becoming increasingly stringent. Although traditional graphene films possess excellent thermal conductivity potential, they generally suffer from problems such as weak interfacial bonding, uneven dispersion of thermally conductive fillers, and rough heat treatment processes. This makes it difficult to significantly improve the actual thermal conductivity and they are prone to defects such as cracks and agglomeration, which restricts their application in high-precision heat dissipation scenarios. For example, conventional boron nitride modified graphene films often have poor interfacial compatibility with polyimide matrices due to insufficient hydroxylation, forming thermal conductivity "breakpoints." While simply adding nanofillers such as calcium carbonate whiskers can improve thermal conductivity, local agglomeration can easily occur due to dispersion process defects, leading to a decline in mechanical properties. In addition, traditional carbonization-graphitization processes often use rapid heating or non-protective atmospheres, which can easily cause disordered orientation of graphite microcrystals and an increase in grain boundary defects, further limiting the potential for improving thermal conductivity.

[0003] In existing technologies, the preparation of polyimide-based graphene films often neglects the role of stepped heat treatment in regulating internal stress, and direct high-temperature treatment easily leads to film cracking and dimensional shrinkage. Meanwhile, the preparation of inorganic particle dispersions often employs single shearing or grinding processes, making it difficult to achieve nanoscale uniform dispersion and affecting the continuity of the thermally conductive network. Therefore, there is an urgent need for a multi-step, collaboratively innovative method to prepare graphene films with high thermal conductivity, high strength, and stable processes, to meet the pressing demand for efficient heat dissipation materials in high-end manufacturing. Summary of the Invention

[0004] Technical problems to be solved In view of the above-mentioned shortcomings of the prior art, the present invention provides a high thermal conductivity graphene film and its preparation method, which can effectively solve the problems of weak interfacial bonding, uneven dispersion of thermally conductive fillers and rough heat treatment process of the prior art graphene film.

[0005] Technical solution To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a high thermal conductivity graphene film, wherein the preparation method comprises: S1. An inorganic particle dispersion was prepared using hydroxylated boron nitride nanopowder and calcium carbonate whiskers as raw materials. S2. Polyamic acid slurry was prepared using 4,4'-diaminodiphenyl ether, p-phenylenediamine, N,N-dimethylacetamide, pyromellitic dianhydride and inorganic particle dispersion as raw materials. S3. Prepare a polyimide film by coating a polyamic acid slurry onto a mirror-finished steel plate; S4. After carbonizing and graphitizing the polyimide film, the resulting material is a high thermal conductivity graphene film.

[0006] Furthermore, the preparation method of hydroxylated boron nitride nanopowder in S1 is as follows: S1.1 Pour 2-3g of nano boron nitride into 100-150mL of sodium hydroxide solution, then pour it into a ball milling jar containing 40g of large agate balls and 60g of small agate balls for ball milling. The result is recorded as the ball milling fraction. S1.2 After centrifugation of the ball-milled components, wash them three times with hydrochloric acid solution, then rinse them repeatedly with deionized water until the washing solution is neutral. After drying, the resulting product is hydroxylated boron nitride nanopowder.

[0007] Furthermore, the concentration of sodium hydroxide solution in S1.1 is 2 mol / L, the ball milling method in S1.1 is ball milling at 200 r / min for 22 h, the centrifugation method in S1.2 is centrifugation at 6000 r / min for 5 min, the concentration of hydrochloric acid solution in S1.2 is 1 mol / L, and the drying method in S1.2 is vacuum drying in a vacuum drying oven at 60℃ for 72 h.

[0008] Furthermore, the preparation method of the inorganic particle dispersion in S1 is as follows: Weigh 5g of hydroxylated boron nitride nanopowder and 5g of calcium carbonate whiskers and pour them into a disperser containing 90g of N,N-dimethylacetamide. Add 0.1-0.2g of silane coupling agent KH-550 and shear disperse at 1500r / min for 2h. Add 200g of glass beads with a particle size of 0.5-1mm and grind disperse at 300r / min for 3h. After filtering out the glass beads, the resulting inorganic particle dispersion is obtained.

[0009] Furthermore, the preparation method of the polyamic acid slurry in S2 is as follows: S2.1 Weigh 10g of 4,4'-diaminodiphenyl ether and 2.5g of p-phenylenediamine and add them to a flask. Then add 200g of N,N-dimethylacetamide and purge with nitrogen to remove oxygen. Stir and dissolve. The resulting product is recorded as the dissolved component. S2.2. Add pyromellitic dianhydride in equal molar batches to the dissolved components until the viscosity reaches 100-120 Pa·S. Then add 30-50 g of inorganic particle dispersion and stir at a stirring speed of 300-400 r / min for 2 hours. After degassing, the resulting material is polyamic acid slurry.

[0010] Furthermore, the method of stirring and dissolving in S2.1 is to stir at a stirring speed of 400-500 r / min until completely dissolved, and the method of degassing in S2.2 is to place under vacuum conditions and let stand for 2-3 hours to degas.

[0011] Furthermore, the preparation method of the polyimide film in S3 is as follows: The polyamic acid slurry is evenly coated onto a clean mirror steel plate. The steel plate is then placed in an oven at 80°C for 1 hour, and then transferred to an oven at 120°C for 30 minutes. The subsequent oven temperatures are 150°C for 30 minutes, 200°C for 10 minutes, 250°C for 10 minutes, 350°C for 5 minutes, and 430°C for 3 minutes. After cooling to room temperature, the film is removed, and the resulting product is a polyimide film.

[0012] Furthermore, the method for carbonization and graphitization in S4 is as follows: S4.1 Place the polyimide film on a high-temperature resistant graphite fixture, stack them layer by layer, and use a 1mm natural graphite sheet as a gap between each layer of polyimide film. After stacking, fix the fixture and place it in a carbonization furnace for carbonization treatment. After cooling to room temperature, record it as the carbonization component. S4.2 The carbonized component is placed in a graphitization furnace for graphitization treatment, and after cooling to room temperature, the resulting high thermal conductivity graphene film is obtained.

[0013] Furthermore, the carbonization treatment in S4.1 is carried out in a vacuum environment with a programmed heating rate of 3℃ / min, and the temperature ranges from 0℃ to 1300℃. The graphitization treatment in S4.2 is carried out in an argon atmosphere at atmospheric pressure with a programmed heating rate of 3℃ / min, and the temperature ranges from 1000℃ to 2700℃.

[0014] A high thermal conductivity graphene film is prepared by a method for preparing a high thermal conductivity graphene film.

[0015] Beneficial effects This invention provides a high thermal conductivity graphene film and its preparation method. Compared with existing technologies, this invention has the following advantages: This invention utilizes surface modification of boron nitride nanopowder to introduce active hydroxyl groups, enhancing the interfacial bonding between boron nitride and the polyimide matrix and forming a highly efficient thermally conductive pathway. Combined with the synergistic dispersion of calcium carbonate whiskers, a three-dimensional thermally conductive network can be constructed within the polyimide matrix, thereby improving the thermal conductivity of the graphene film. The inorganic particle dispersion is surface-modified with silane coupling agent KH-550, and combined with high-speed shearing and glass bead milling to achieve uniform dispersion of nanoparticles, thus avoiding performance fluctuations caused by agglomeration. Degassing treatment eliminates bubble defects, ensuring film uniformity. Furthermore, the polyimide film undergoes stepped temperature curing, effectively reducing internal stress and preventing crack formation. Carbonization and graphitization further optimize the orientation of graphite microcrystals and improve crystallinity, giving the film material both high thermal conductivity and high mechanical strength.

[0016] In this invention, the active surface of hydroxylated boron nitride can form hydrogen bonds / covalent bonds with polyamic acid molecular chains, thereby improving the compatibility of the inorganic and organic interfaces. The addition of calcium carbonate whiskers not only serves as a thermally conductive filler but also enhances the mechanical load-bearing capacity of the graphene film through the bridging effect of the whiskers, achieving dual-function optimization of "thermal conductivity and mechanical properties". In the preparation of polyamic acid slurry, equimolar addition of pyromellitic dianhydride controls the molecular weight distribution, ensuring that the slurry viscosity is suitable for the coating process. The stepped heat treatment is matched with the heating rate of carbonization / graphification, which can avoid structural damage caused by thermal shock and achieve a gradual phase transition from polyimide to graphene. Finally, a vacuum environment is used in the carbonization stage to avoid oxidation, and argon gas is introduced in the graphitization stage to maintain normal pressure, which can ensure the safety of high-temperature processing. The 1mm thick natural graphite sheet spacer layer plays a thermal buffering role in the stacked carbonization, thereby reducing interlayer thermal stress and improving the yield of large-size film materials.

[0017] This patent achieves the preparation of graphene films with high thermal conductivity, high strength, and stable process through collaborative innovation across the entire process of "raw material modification - dispersion optimization - structural regulation - high temperature phase transition". It has significant application value in fields with high thermal conductivity requirements such as communications and new energy vehicles. Detailed Implementation

[0018] 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. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] The present invention will be further described below with reference to embodiments.

[0020] The sources of some components in the examples and comparative examples are as follows: Nano boron nitride, Shanghai Maoguo Nanotechnology Co., Ltd. Sodium hydroxide, Sinopharm Chemical Reagent Co., Ltd. Hydrochloric acid, Sinopharm Chemical Reagent Co., Ltd.; Calcium carbonate whiskers, Shanghai Maclean Biochemical Technology Co., Ltd.; N,N-Dimethylacetamide, Sinopharm Chemical Reagent Co., Ltd.; Silane coupling agent KH-550, Aladdin Reagent (Shanghai) Co., Ltd.; 4,4'-Diaminodiphenyl ether, Aladdin Reagent (Shanghai) Co., Ltd.; p-Phenylenediamine, Aladdin Reagent (Shanghai) Co., Ltd.; Pyromellitic dianhydride, Aladdin Reagent (Shanghai) Co., Ltd.

[0021] Example 1 This embodiment describes a method for preparing a high thermal conductivity graphene film. The preparation method is as follows: S1. An inorganic particle dispersion was prepared using hydroxylated boron nitride nanopowder and calcium carbonate whiskers as raw materials. The preparation method of hydroxylated boron nitride nanopowder is as follows: S1.1 Pour 2g of nano boron nitride into 100mL of sodium hydroxide solution with a concentration of 2mol / L, then pour it into a ball milling jar containing 40g of large agate balls and 60g of small agate balls and ball mill at a speed of 200r / min for 22h. The result is recorded as the ball milling component. S1.2. After centrifuging the ball-milled component at 6000 r / min for 5 min, wash it three times with a 1 mol / L hydrochloric acid solution, then rinse it repeatedly with deionized water until the washing solution is neutral, and then vacuum dry it in a vacuum drying oven at 60℃ for 72 h to obtain hydroxylated boron nitride nanopowder.

[0022] The preparation method of inorganic particle dispersion is as follows: Weigh 5g of hydroxylated boron nitride nanopowder and 5g of calcium carbonate whiskers and pour them into a disperser containing 90g of N,N-dimethylacetamide. Add 0.1g of silane coupling agent KH-550 and shear disperse at 1500r / min for 2h. Add 200g of glass beads with a particle size of 0.5mm and grind disperse at 300r / min for 3h. After filtering out the glass beads, the resulting inorganic particle dispersion is obtained.

[0023] S2. Polyamic acid slurry was prepared using 4,4'-diaminodiphenyl ether, p-phenylenediamine, N,N-dimethylacetamide, pyromellitic dianhydride and inorganic particle dispersion as raw materials. The preparation method of polyamic acid slurry is as follows: S2.1 Weigh 10g of 4,4'-diaminodiphenyl ether and 2.5g of p-phenylenediamine and add them to a flask. Then add 200g of N,N-dimethylacetamide and purge with nitrogen to remove oxygen. Stir at 400r / min until completely dissolved. The resulting product is recorded as the dissolved component. S2.2. Add pyromellitic dianhydride in equal molar batches to the dissolved components until the viscosity reaches 100 Pa·S. Then add 30 g of inorganic particle dispersion, stir at 300 r / min for 2 h, and let stand under vacuum for 2 h to remove bubbles. The resulting product is polyamic acid slurry.

[0024] S3. Prepare a polyimide film by coating a polyamic acid slurry onto a mirror-finished steel plate; The preparation method of the polyimide film is as follows: The polyamic acid slurry is evenly coated onto a clean mirror steel plate. The steel plate is then placed in an oven at 80°C for 1 hour, and then transferred to an oven at 120°C for 30 minutes. The subsequent oven temperatures are 150°C for 30 minutes, 200°C for 10 minutes, 250°C for 10 minutes, 350°C for 5 minutes, and 430°C for 3 minutes. After cooling to room temperature, the film is removed, and the resulting product is a polyimide film.

[0025] S4. After carbonizing and graphitizing the polyimide film, the resulting material is a high thermal conductivity graphene film. The method for carbonization and graphitization is as follows: S4.1 Place the polyimide film on a high-temperature resistant graphite fixture, stack them layer by layer, and use natural graphite sheets with a 1mm gap between each layer of polyimide film. After stacking, fix the fixture and place it in a carbonization furnace for carbonization treatment. After cooling to room temperature, record it as the carbonization component. The carbonization treatment conditions are a vacuum environment, with a programmed heating rate of 3℃ / min, and the temperature range is 0℃ to 1300℃. S4.2 The carbonized component is placed in a graphitization furnace for graphitization treatment. After cooling to room temperature, the resulting high thermal conductivity graphene film is obtained. The graphitization treatment conditions are argon gas and normal pressure environment, with a programmed heating rate of 3℃ / min, and the temperature range is 1000℃ to 2700℃.

[0026] A high thermal conductivity graphene film is prepared by a method for preparing a high thermal conductivity graphene film.

[0027] Example 2 This embodiment describes a method for preparing a high thermal conductivity graphene film. The preparation method is as follows: S1. An inorganic particle dispersion was prepared using hydroxylated boron nitride nanopowder and calcium carbonate whiskers as raw materials. The preparation method of hydroxylated boron nitride nanopowder is as follows: S1.1 Pour 3g of nano boron nitride into 150mL of sodium hydroxide solution with a concentration of 2mol / L, then pour it into a ball milling jar containing 40g of large agate balls and 60g of small agate balls and ball mill at a speed of 200r / min for 22h. The result is recorded as the ball milling component. S1.2. After centrifuging the ball-milled component at 6000 r / min for 5 min, wash it three times with a 1 mol / L hydrochloric acid solution, then rinse it repeatedly with deionized water until the washing solution is neutral, and then vacuum dry it in a vacuum drying oven at 60℃ for 72 h to obtain hydroxylated boron nitride nanopowder.

[0028] The preparation method of inorganic particle dispersion is as follows: Weigh 5g of hydroxylated boron nitride nanopowder and 5g of calcium carbonate whiskers and pour them into a disperser containing 90g of N,N-dimethylacetamide. Add 0.2g of silane coupling agent KH-550 and shear disperse at 1500r / min for 2h. Add 200g of glass beads with a particle size of 1mm and grind disperse at 300r / min for 3h. After filtering out the glass beads, the resulting inorganic particle dispersion is obtained.

[0029] S2. Polyamic acid slurry was prepared using 4,4'-diaminodiphenyl ether, p-phenylenediamine, N,N-dimethylacetamide, pyromellitic dianhydride and inorganic particle dispersion as raw materials. The preparation method of polyamic acid slurry is as follows: S2.1 Weigh 10g of 4,4'-diaminodiphenyl ether and 2.5g of p-phenylenediamine and add them to a flask. Then add 200g of N,N-dimethylacetamide and purge with nitrogen to remove oxygen. Stir at 500r / min until completely dissolved. The resulting product is recorded as the dissolved component. S2.2. Add pyromellitic dianhydride in equal molar batches to the dissolved components until the viscosity reaches 120 Pa·S. Then add 50 g of inorganic particle dispersion, stir at 400 r / min for 2 h, and let stand under vacuum for 3 h to degas. The resulting product is polyamic acid slurry.

[0030] S3. Prepare a polyimide film by coating a polyamic acid slurry onto a mirror-finished steel plate; The preparation method of the polyimide film is as follows: The polyamic acid slurry is evenly coated onto a clean mirror steel plate. The steel plate is then placed in an oven at 80°C for 1 hour, and then transferred to an oven at 120°C for 30 minutes. The subsequent oven temperatures are 150°C for 30 minutes, 200°C for 10 minutes, 250°C for 10 minutes, 350°C for 5 minutes, and 430°C for 3 minutes. After cooling to room temperature, the film is removed, and the resulting product is a polyimide film.

[0031] S4. After carbonizing and graphitizing the polyimide film, the resulting material is a high thermal conductivity graphene film. The method for carbonization and graphitization is as follows: S4.1 Place the polyimide film on a high-temperature resistant graphite fixture, stack them layer by layer, and use natural graphite sheets with a 1mm gap between each layer of polyimide film. After stacking, fix the fixture and place it in a carbonization furnace for carbonization treatment. After cooling to room temperature, record it as the carbonization component. The carbonization treatment conditions are a vacuum environment, with a programmed heating rate of 3℃ / min, and the temperature range is 0℃ to 1300℃. S4.2 The carbonized component is placed in a graphitization furnace for graphitization treatment. After cooling to room temperature, the resulting high thermal conductivity graphene film is obtained. The graphitization treatment conditions are argon gas and normal pressure environment, with a programmed heating rate of 3℃ / min, and the temperature range is 1000℃ to 2700℃.

[0032] A high thermal conductivity graphene film is prepared by a method for preparing a high thermal conductivity graphene film.

[0033] Example 3 This embodiment describes a method for preparing a high thermal conductivity graphene film. The preparation method is as follows: S1. An inorganic particle dispersion was prepared using hydroxylated boron nitride nanopowder and calcium carbonate whiskers as raw materials. The preparation method of hydroxylated boron nitride nanopowder is as follows: S1.1 Pour 3g of nano boron nitride into 130mL of sodium hydroxide solution with a concentration of 2mol / L, then pour it into a ball milling jar containing 40g of large agate balls and 60g of small agate balls and ball mill at a speed of 200r / min for 22h. The result is recorded as the ball milling component. S1.2. After centrifuging the ball-milled component at 6000 r / min for 5 min, wash it three times with a 1 mol / L hydrochloric acid solution, then rinse it repeatedly with deionized water until the washing solution is neutral, and then vacuum dry it in a vacuum drying oven at 60℃ for 72 h to obtain hydroxylated boron nitride nanopowder.

[0034] The preparation method of inorganic particle dispersion is as follows: Weigh 5g of hydroxylated boron nitride nanopowder and 5g of calcium carbonate whiskers and pour them into a disperser containing 90g of N,N-dimethylacetamide. Add 0.2g of silane coupling agent KH-550 and shear disperse at 1500r / min for 2h. Add 200g of glass beads with a particle size of 0.8mm and grind disperse at 300r / min for 3h. After filtering out the glass beads, the resulting inorganic particle dispersion is obtained.

[0035] S2. Polyamic acid slurry was prepared using 4,4'-diaminodiphenyl ether, p-phenylenediamine, N,N-dimethylacetamide, pyromellitic dianhydride and inorganic particle dispersion as raw materials. The preparation method of polyamic acid slurry is as follows: S2.1 Weigh 10g of 4,4'-diaminodiphenyl ether and 2.5g of p-phenylenediamine and add them to a flask. Then add 200g of N,N-dimethylacetamide and purge with nitrogen to remove oxygen. Stir at 500r / min until completely dissolved. The resulting product is recorded as the dissolved component. S2.2. Add pyromellitic dianhydride in equal molar batches to the dissolved components until the viscosity reaches 110 Pa·S. Then add 40 g of inorganic particle dispersion, stir at 400 r / min for 2 h, and let stand under vacuum for 3 h to degas. The resulting product is polyamic acid slurry.

[0036] S3. Prepare a polyimide film by coating a polyamic acid slurry onto a mirror-finished steel plate; The preparation method of the polyimide film is as follows: The polyamic acid slurry is evenly coated onto a clean mirror steel plate. The steel plate is then placed in an oven at 80°C for 1 hour, and then transferred to an oven at 120°C for 30 minutes. The subsequent oven temperatures are 150°C for 30 minutes, 200°C for 10 minutes, 250°C for 10 minutes, 350°C for 5 minutes, and 430°C for 3 minutes. After cooling to room temperature, the film is removed, and the resulting product is a polyimide film.

[0037] S4. After carbonizing and graphitizing the polyimide film, the resulting material is a high thermal conductivity graphene film. The method for carbonization and graphitization is as follows: S4.1 Place the polyimide film on a high-temperature resistant graphite fixture, stack them layer by layer, and use natural graphite sheets with a 1mm gap between each layer of polyimide film. After stacking, fix the fixture and place it in a carbonization furnace for carbonization treatment. After cooling to room temperature, record it as the carbonization component. The carbonization treatment conditions are a vacuum environment, with a programmed heating rate of 3℃ / min, and the temperature range is 0℃ to 1300℃. S4.2 The carbonized component is placed in a graphitization furnace for graphitization treatment. After cooling to room temperature, the resulting high thermal conductivity graphene film is obtained. The graphitization treatment conditions are argon gas and normal pressure environment, with a programmed heating rate of 3℃ / min, and the temperature range is 1000℃ to 2700℃.

[0038] A high thermal conductivity graphene film is prepared by a method for preparing a high thermal conductivity graphene film.

[0039] Comparative Example 1 The high thermal conductivity graphene film and its preparation method provided in this comparative example are largely the same as those in Example 1. The main difference is that the hydroxylated boron nitride nanopowder in Example 1 is replaced with calcium carbonate whiskers.

[0040] Comparative Example 2 The high thermal conductivity graphene film and its preparation method provided in this comparative example are largely the same as those in Example 1. The main difference is that the calcium carbonate whiskers in Example 1 are replaced with hydroxylated boron nitride nanoparticles in this comparative example.

[0041] Performance testing The high thermal conductivity graphene films prepared in Examples 1-3 and Comparative Examples 1-2 were labeled as Example 1, Example 2, Example 3, Comparative Example 1, and Comparative Example 2, respectively. The performance of Examples 1-3 and Comparative Examples 1-2 was then tested. The specific testing methods and items are as follows: 1. The tensile strength and tensile modulus of Examples 1-3 and Comparative Examples 1-2 were tested according to the standard GB / T 1040.3-2006, and the data obtained are recorded in the table below; 2. The in-plane thermal conductivity of Examples 1-3 and Comparative Examples 1-2 was tested according to the method of ASTM E1461, and the data obtained are recorded in the table below;

[0042] The data in the table above shows that the mechanical properties and thermal conductivity of the high thermal conductivity graphene films in Examples 1-3 are better than those in Comparative Examples 1-2, indicating that the high thermal conductivity graphene films prepared by the method of this invention have better application value.

[0043] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0044] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of preparing a high thermal conductive graphene film, characterized by, The preparation method is: S1, with hydroxylated boron nitride nano powder and calcium carbonate whisker as raw material to prepare inorganic particle dispersion liquid; S2, with 4, 4'-diamino diphenyl ether, p-phenylenediamine, N, N-dimethylacetamide, pyromellitic dianhydride and inorganic particle dispersion liquid as raw material to prepare polyamide acid slurry; S3, polyamide acid slurry is coated on mirror surface steel plate to prepare polyimide film; S4, after carbonization and graphitization treatment of polyimide film, the obtained is high thermal conductivity graphene film.

2. The method of claim 1, wherein the graphene film has a thermal conductivity of at least 1,000 W / mK. The preparation method of hydroxylated boron nitride nano powder in S1 is: S1.1, 2-3g nano boron nitride is poured into 100-150mL sodium hydroxide solution, then poured into the ball mill tank containing 40g large agate ball and 60g small agate ball for ball milling treatment, and the obtained is marked as ball milling component; S1.2, after centrifugal treatment of the ball milling component, it is washed with hydrochloric acid solution for 3 times, then washed with deionized water repeatedly until the washing liquid is neutral, and after drying treatment, the obtained is hydroxylated boron nitride nano powder.

3. The method of claim 2, wherein the graphene film has a thermal conductivity of at least 5000 W / mK. The concentration of sodium hydroxide solution in S1.1 is 2mol / L, the ball milling method in S1.1 is ball milling at a speed of 200r / min for 22h, the centrifugal treatment method in S1.2 is centrifugal treatment at a speed of 6000r / min for 5min, the concentration of hydrochloric acid solution in S1.2 is 1mol / L, and the drying method in S1.2 is vacuum drying in 60℃ vacuum drying box for 72h.

4. The method of claim 1, wherein the graphene film has a thermal conductivity of at least 1,000 W / mK. The preparation method of inorganic particle dispersion liquid in S1 is: 5g hydroxylated boron nitride nano powder and 5g calcium carbonate whisker are weighed and poured into a disperser containing 90g N, N-dimethylacetamide, 0.1-0.2g silane coupling agent KH-550 is added, and then shearing dispersion is carried out at a speed of 1500r / min for 2h, 200g glass beads with a particle size of 0.5-1mm are added, and then grinding dispersion is carried out at a speed of 300r / min for 3h, and then the glass beads are filtered out, and the obtained is inorganic particle dispersion liquid.

5. The method of claim 1, wherein the graphene film has a thermal conductivity of at least 1,000 W / mK. The preparation method of polyamide acid slurry in S2 is: S2.1, 10g 4, 4'-diamino diphenyl ether and 2.5g p-phenylenediamine are weighed and added into a flask, 200g N, N-dimethylacetamide is added, and then oxygen is removed by nitrogen blowing, and after stirring and dissolving, the obtained is marked as dissolved component; S2.2, pyromellitic dianhydride is gradually added in equal molar batches to the dissolved component, until the viscosity reaches 100-120Pa·S, then 30-50g inorganic particle dispersion liquid is added, stirring is carried out at a speed of 300-400r / min for 2h, and then defoaming treatment is carried out, and the obtained is polyamide acid slurry.

6. The method of claim 5, wherein the graphene film has a thermal conductivity of at least 5000 W / mK. The stirring and dissolving method in S2.1 is stirring at a speed of 400-500r / min until complete dissolution, and the defoaming treatment method in S2.2 is placing under vacuum condition for 2-3h defoaming.

7. The method of claim 1, wherein the graphene film has a thermal conductivity of at least 1,000 W / mK. The preparation method of polyimide film in S3 is: The polyamide acid slurry is uniformly coated on a clean mirror surface steel plate, then the steel plate is placed in an oven at 80℃ for 1h, then transferred to an oven at 120℃ for 30min, followed by 150℃ for 30min, 200℃ for 10min, 250℃ for 10min, 350℃ for 5min, 430℃ for 3min, and then removed after cooling to room temperature, and the obtained is a polyimide film.

8. The method of claim 1, wherein the graphene film has a thermal conductivity of at least 1,000 W / mK. The method for carbonizing and graphitizing in S4 is: S4.1, the polyimide film is placed on a high-temperature-resistant graphite tool, stacked layer by layer, and 1mm natural graphite sheet is used as a spacer between each layer of polyimide film, after stacking, the tool is fixed and placed in a carbonization furnace for carbonization treatment, and after cooling to room temperature, it is recorded as a carbonized component; S4.2, the carbonized component is placed in a graphitization furnace for graphitization treatment, and after cooling to room temperature, the obtained is a high-thermal-conductivity graphene film.

9. The method of claim 8, wherein the graphene film has a thermal conductivity of at least 5000 W / mK. The carbonization treatment conditions in S4.1 are a vacuum environment, programmed temperature rise at a rate of 3℃ / min, and the temperature is 0℃ to 1300℃, and the graphitization treatment conditions in S4.2 are an argon gas, normal pressure environment, programmed temperature rise at a rate of 3℃ / min, and the temperature is 1000℃ to 2700℃.

10. A high thermal conductivity graphene film, characterized by, A high-thermal-conductivity graphene film is prepared by the method of any one of claims 1-9.

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