Graphene heat-conducting film, preparation method and intelligent terminal

Abstract

The application provides a graphene heat-conducting film and a preparation method thereof and a smart terminal, and relates to the technical field of heat-conducting films.In the application, a graphene precursor film layer is prepared first, the graphene precursor film layer comprises a plurality of polymer film layers and a plurality of graphene oxide film layers which are alternately stacked, then carbonization treatment is performed on the graphene precursor film layer so that the polymer film layers and the graphene oxide film layers are graphitized in the process, and then graphitization treatment is performed on the polymer film layers and the graphene oxide film layers after carbonization so that the polymer film layers and the graphene oxide film layers are graphitized in the process, so that the graphene precursor film is prepared into a graphene heat-conducting film with a larger thickness after carbonization and graphitization treatment, the preparation process is simple, mass production is facilitated, and the obtained graphene heat-conducting film has better heat conductivity.

Description

Technical Field

[0001] This application relates to the field of graphene technology, specifically to a graphene thermal conductive film and its preparation method, and a smart terminal. Background Technology

[0002] Graphene is a planar two-dimensional layered material composed of carbon atoms arranged in a hexagonal honeycomb lattice with sp2 hybrid orbitals. It possesses excellent physicochemical properties and a theoretical thermal conductivity as high as 5300 W / (m·K). Compared with traditional thermally conductive materials (graphite, aluminum, copper, etc.), it has high thermal conductivity and is lightweight, making it one of the ideal thermally conductive materials.

[0003] In existing technologies, the preparation of thick graphene thermal conductive films generally involves laminating multiple graphene thermal conductive films together or repeatedly coating a substrate with graphene slurry. However, the method of laminating multiple graphene thermal conductive films results in poor thermal conductivity at the interface between the layers and low preparation efficiency. The method of repeatedly coating graphene slurry requires the previous coating to be basically sculpted before the second coating can be applied, and the subsequent coating can damage the film structure of the previous process, leading to larger defects and unsatisfactory thermal conductivity in the prepared graphene thermal conductive film. Summary of the Invention

[0004] This application provides a graphene thermal conductive film and its preparation method, as well as a smart terminal, aiming to solve the problems of unsatisfactory thermal conductivity and low preparation efficiency of the thick graphene thermal conductive film prepared by existing methods.

[0005] The first aspect of this application provides a method for preparing a graphene thermally conductive film, comprising the following steps:

[0006] A graphene precursor film is prepared, the graphene precursor film comprising a plurality of polymer film layers and a plurality of graphene oxide film layers, wherein the polymer film layers and the graphene oxide film layers are alternately stacked.

[0007] The graphene precursor film was carbonized under a protective atmosphere to obtain a carbonized graphene film.

[0008] Under a protective atmosphere, the carbonized graphene film is graphitized to obtain a graphene foam film.

[0009] The obtained film is pressed to obtain the graphene thermal conductive film.

[0010] In some embodiments of this application, the step of preparing the graphene precursor film includes:

[0011] A graphene slurry is prepared, the graphene slurry comprising graphene oxide, a solvent, and a pH adjuster;

[0012] The graphene slurry is coated onto at least one side of the polymer film and dried to obtain the graphene precursor film.

[0013] In some embodiments of this application, the graphene slurry further includes carbon nanotubes, wherein the mass ratio of the carbon nanotubes to the graphene oxide is (1:1). ～ 100): 100;

[0014] Preferably, the mass ratio of the carbon nanotubes to the graphene oxide is (10:1). ～ 30): 100.

[0015] In some embodiments of this application, the polymer film layer is selected from one or more of polyarylexadiazole, polyimide, polyamic acid, and polyacrylonitrile.

[0016] In some embodiments of this application, the graphene slurry further includes boric acid, wherein the mass ratio of boric acid to graphene oxide is (0.1-10):100;

[0017] Preferably, the mass ratio of boric acid to graphene oxide is (1-2.5):100.

[0018] In some embodiments of this application, the step of preparing the graphene slurry includes:

[0019] The graphene oxide, boric acid, and pH adjuster are dispersed in the solvent according to a preset ratio to prepare a graphene slurry. The mass percentage of the slurry in the graphene slurry is 2% to 7%, and the pH value of the graphene slurry is 5 to 10.

[0020] In some embodiments of this application, the process of carbonizing the graphene precursor film further includes:

[0021] The graphene precursor film was subjected to a process at 100°C. ～ Let stand at 400℃ for 0.5 hours ～ 2H.

[0022] In some embodiments of this application, the carbonization treatment temperature is 800°C. ～ The carbonization process was carried out at 1500℃ for 0.5 hours. ～ 5H;

[0023] And / or, the graphitization treatment temperature is 2700°C. ～ The graphitization process was carried out at 3200℃ for 0.5 hours. ～ 10H;

[0024] And / or, the drying temperature is 40°C. ～ 105℃;

[0025] And / or, the pressure of the pressing process is 10 MPa. ～ 200MPa;

[0026] And / or, the solvent is selected from one or more of water, ethanol, N,N-dimethylformamide and N-methylpyrrolidone.

[0027] A second aspect of this application provides a graphene thermal conductive film, wherein the graphene thermal conductive film is prepared by the method for preparing the graphene thermal conductive film.

[0028] A third aspect of this application provides a smart terminal, the smart terminal including a motherboard and the graphene thermal conductive film, the graphene thermal conductive film being used to accelerate the heat dissipation of the motherboard.

[0029] In this application, a graphene precursor film is first prepared, comprising several polymer films and several graphene oxide films stacked alternately. The graphene precursor film is then carbonized to remove most of the oxygen- and nitrogen-containing functional groups and inorganic salt impurities from both the polymer and graphene oxide films. The carbonized polymer and graphene oxide films are then graphitized to repair internal defects in the graphene structure. This process, involving carbonization and graphitization, yields a thick graphene thermally conductive film. The preparation process is simple and conducive to mass production. Furthermore, since the polymer film layer and the graphene oxide film layer are alternately stacked, and the polymer film layer and the adjacent graphene oxide film layer are carbonized or graphitized in the same process, the graphene foam film formed by the polymer film layer and the graphene foam film formed by the adjacent graphene oxide film layer can form a mutually interlocking or cross-linked structure, which increases the contact area and interaction force at the interface, thereby giving the obtained graphene thermal conductive film better thermal conductivity. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic flowchart of an embodiment of the method for preparing a graphene thermally conductive film provided in this application.

[0032] Figure 2 This is a schematic flowchart of another embodiment of the method for preparing the graphene thermal conductive film provided in this application.

[0033] Figure 3 This is a schematic diagram of the structure of one embodiment of the graphene precursor film provided in this application. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art, and the materials or reagents used in the embodiments and comparative examples of this application are commercially available. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0036] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of embodiments. Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is indicated herein, it means including any referenced number (fraction or integer) within the indicated range.

[0037] In the description of this application, the term "comprising" means "including but not limited to".

[0038] The terms “multiple,” “multiple times,” or similar expressions refer to two or more times, such as two, three, four, five, six, etc.

[0039] The term "and / or" encompasses any one of two or more of the listed items, as well as any and all combinations of the listed items. These combinations include any two listed items, any number of listed items, or a combination of all listed items. For example, "A and / or B" includes three parallel solutions: A, B, and A+B. Similarly, the technical solution "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (i.e., all connected by "logical OR"), any and all combinations of A, B, C, and D, including combinations of any two or three of A, B, C, and D, and combinations of all four of A, B, C, and D (i.e., all connected by "logical AND").

[0040] The technical solution of this application is as follows:

[0041] Firstly, please refer to the appendix. Figure 1 and Figure 2 This application provides a method for preparing a graphene thermally conductive film, comprising the following steps:

[0042] S1 prepares a graphene precursor film, the graphene precursor film comprising a plurality of polymer film layers and a plurality of graphene oxide film layers, the polymer film layers and the graphene oxide film layers being alternately stacked.

[0043] It should be noted that the specific number of polymer film layers and graphene oxide film layers in this application is not limited. The number of polymer film layers and graphene oxide film layers can be the same or different. In some embodiments of this application, the number of polymer film layers and graphene oxide film layers can be the same. For example, the graphene precursor film may include only one polymer film layer and one graphene oxide film layer, with the graphene oxide film layer stacked on one side of the polymer film layer. For another example, such as... Figure 3As shown, the graphene precursor film includes multiple polymer film layers (two or more polymer film layers) and multiple graphene oxide film layers (two or more polymer film layers and graphene oxide film layers). The graphene precursor film includes polymer film layers, graphene oxide film layers, polymer film layers, graphene oxide film layers, etc., stacked sequentially. In other embodiments of this application, the number of polymer film layers and the number of graphene oxide film layers may also be the same. For example, the graphene precursor film includes N polymer film layers and (N+1) graphene oxide film layers, where N is a positive integer. For example, the graphene precursor film includes one polymer film layer and two graphene oxide film layers, with a graphene oxide film layer on each side of the polymer film layer. Another example is that the graphene precursor film includes two polymer film layers and three graphene oxide film layers, and the graphene precursor film includes graphene oxide film layers, polymer film layers, graphene oxide film layers, polymer film layers, graphene oxide film layers, etc., stacked sequentially.

[0044] It should be noted that the preparation of the graphene precursor film in this application can be achieved by first preparing a polymer film layer and graphene oxide separately, then performing surface treatment on the polymer film layer and / or graphene oxide film layer, and then sequentially stacking the surface-treated polymer film layer and graphene oxide film layer. Alternatively, the preparation of the graphene precursor film in this application can be achieved by first preparing a polymer film layer and graphene slurry, then coating the polymer film layer with the graphene slurry, and finally drying the coated graphene slurry to form a graphene oxide film layer on the polymer film layer.

[0045] Exemplarily, the step of preparing the graphene precursor film includes: S11 preparing a graphene slurry, wherein the graphene slurry includes graphene oxide, a solvent, and a pH adjuster. S12 coating the graphene slurry onto at least one side of the polymer film layer and drying to obtain the graphene precursor film. This embodiment, by directly coating the graphene slurry onto the polymer film layer, allows for better interpenetration between the polymer film layer and the graphene oxide film layer during carbonization and graphitization processes. This further increases the degree of intercalation or cross-linking between the graphene foam film formed by the polymer film layer and the graphene foam film formed by the adjacent graphene oxide film layer, improving the contact area and interaction force at the interface, thereby resulting in a graphene thermally conductive film with better thermal conductivity.

[0046] It should be noted that there are no special restrictions on the coating method for applying the slurry to the substrate; any conventional coating method in the art, such as blade coating, is acceptable. In this invention, the coating thickness is preferably 3–7 mm, specifically 3 mm, 4 mm, 5 mm, 6 mm, or 7 mm. In this invention, after coating the graphene slurry onto the polymer film layer, the coated graphene slurry is dried to obtain a graphene oxide film layer. The drying temperature is 40°C. ～105℃, preferably 50~80℃, specifically 50℃, 60℃, 70℃, or 80℃.

[0047] In some embodiments of this application, the polymer film layer is selected from one or more of polyarylene diazole, polyimide, polyamic acid, and polyacrylonitrile. Exemplarily, the graphene thermal conductive film obtained by using polyarylene diazole as the polymer film layer has a large thickness and good horizontal and vertical thermal conductivity, and can solve the problem of easy powder shedding in graphene thermal conductive films prepared by polyarylene diazole.

[0048] In some embodiments of this application, the graphene slurry includes graphene oxide, a solvent, and a pH adjuster. The solvent is selected from at least one of water, ethanol, N,N-dimethylformamide, and N-methylpyrrolidone. The pH adjuster can be ammonia, sodium carbonate, or ammonium bicarbonate solution. Exemplarily, the solvent is water, and the pH adjuster is ammonia. In some embodiments of this application, the graphene slurry may also include other functional additives. Exemplarily, the graphene slurry also includes a dispersing agent, which is used to reduce the viscosity of the graphene slurry, resulting in uniform coating and a smooth film. The type of dispersing agent is not limited; for example, it can be one or more of organosilicon resin, sodium dodecylbenzenesulfonate, and graphene quantum dots. In some embodiments of this application, the graphene slurry may also include a reducing agent. The type of reducing agent is not limited; for example, it can be one or more of hydroiodic acid, sodium borohydride, hydrazine hydrate, or sodium ascorbate.

[0049] In some embodiments of this application, the graphene slurry further includes carbon nanotubes, which include at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, carboxylated carbon nanotubes, and aminated carbon nanotubes. The length-to-diameter ratio (aspect ratio) of the carbon nanotubes is 50-2000, and the mass ratio of the carbon nanotubes to the graphene oxide is (1 / 2)... ～ 100):100. Exemplarily, the carbon nanotubes are carboxylated carbon nanotubes with an aspect ratio of 150-200, and the mass ratio of the carbon nanotubes to the graphene oxide is (2... ～ 80):100, further, the mass ratio of the carbon nanotubes to the graphene oxide is (5):100. ～ 60):100, further, the mass ratio of the carbon nanotubes to the graphene oxide is (10):100. ～ 30):100. In this embodiment, carbon nanotubes are added to the graphene slurry. The carbon nanotubes can penetrate into the polymer film layer better, which can further increase the degree of intercalation or cross-linking between the graphene foam film formed by the polymer film layer and the graphene foam film formed by the adjacent graphene oxide film layer. This improves the contact area and interaction force at the interface, thereby making the obtained graphene thermal conductive film have better thermal conductivity.

[0050] In some embodiments of this application, the graphene slurry further includes boric acid, wherein the mass ratio of boric acid to graphene oxide is (0.1–10):100. Further, the mass ratio of boric acid to graphene oxide is (0.2–8):100. Further, the mass ratio of boric acid to graphene oxide is (0.5–6):100. Further, the mass ratio of boric acid to graphene oxide is (0.8–4.5):100. Further, the mass ratio of boric acid to graphene oxide is (1.0–2.5):100.

[0051] In some embodiments of this application, the graphene slurry further includes carbon nanotubes and boric acid, the solvent is deionized water, the pH adjuster is ammonia, and the mass ratio of carbon nanotubes:boric acid:graphene oxide is (1 / 2) * ... ～ 100):(0.1~10):100. Further, carbon nanotubes:boric acid:graphene oxide = (10 ～ 30): (1~2.5): 100. The steps for preparing graphene slurry include: dispersing the graphene oxide, boric acid, carbon nanotubes and pH adjuster in deionized water according to a preset ratio to prepare graphene slurry, wherein the mass percentage of the slurry in the graphene slurry is 2%~7%, and the pH value of the graphene slurry is 5~10.

[0052] After step S12 and before carbonizing the graphene precursor film, the step of preparing the graphene precursor film further includes: S13 heating the graphene precursor film at 100°C. ～ Treatment at 400℃ for 0.5 hours ～ 2H. In this embodiment, the graphene precursor film is first kept at a low temperature of 100℃ to 400℃ for 0.5H to 2H to remove epoxy groups, hydroxyl groups, and ammonium salts from the graphene oxide, which is beneficial to improving the purity and structural regularity of the graphene thermally conductive film in this application. Specifically, the graphene precursor film obtained in step S1 is kept at 300℃ for 1H under air or a protective atmosphere to obtain a low-temperature graphene film after low-temperature treatment.

[0053] In step S2, the low-temperature graphene film obtained in step S2 is carbonized under a protective atmosphere to obtain a carbonized graphene film.

[0054] It should be noted that, in this application, "protective atmosphere" refers to an inert gas atmosphere, wherein the inert gas includes one or more of nitrogen, helium, neon, argon, krypton, and xenon. For example, argon is used as the inert gas. Carbonization is used to remove salt impurities (e.g.) from the graphene precursor film and repair some defects. The specific process conditions for carbonization are not a major improvement of this application and are not limited here. For example, the heating rate of the carbonization process is preferably 5–50 °C / min, specifically 5 °C / min, 10 °C / min, 15 °C / min, 20 °C / min, 25 °C / min, 30 °C / min, 35 °C / min, 40 °C / min, 45 °C / min, or 50 °C / min. The preferred temperature for the carbonization treatment is 800–1500℃, specifically 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, 1200℃, 1250℃, 1300℃, 1350℃, 1400℃, 1450℃, and 1500℃. In this invention, the preferred holding time for the carbonization treatment is 1 hour to 6 hours, specifically 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours.

[0055] S3. Under a protective atmosphere, the carbonized graphene film is graphitized to obtain a graphene foam film. Exemplarily, the graphitization temperature is 2700℃~3200℃, and the graphitization time is 0.5H to 10H. It should be noted that the specific process conditions for graphitization are not a major improvement of this application and are not limited here. It is understood that during the graphitization process, under high-temperature conditions, the defective structure inside the graphene is repaired, the conjugated structure is restored, and phonon transport channels are formed, significantly improving the thermal conductivity of the graphene film.

[0056] For example, the heating rate of the graphitization treatment is preferably 5-50℃ / min, specifically 5℃ / min, 10℃ / min, 15℃ / min, 20℃ / min, 25℃ / min, 30℃ / min, 35℃ / min, 40℃ / min, 45℃ / min, or 50℃ / min. The temperature of the graphitization treatment is preferably 2700℃-3200℃, specifically 2700℃, 2800℃, 2900℃, 2950℃, 3000℃, 3150℃, 3100℃, 3150℃, or 3200℃. In this invention, the holding time of the graphitization treatment is preferably 1h-6h, specifically 1h, 2h, 3h, 4h, 5h, or 6h.

[0057] S4 involves pressing the obtained film to obtain the graphene thermally conductive film. It is understood that calendering the graphene foam film can increase its density, thereby resulting in a graphene thermally conductive film with better thermal conductivity and a smoother structure. Exemplarily, the calendering process includes one or more of rolling and flat pressing, with a pressure of 10 MPa to 200 MPa.

[0058] Example 1

[0059] Preparation of graphene slurry: A certain amount of graphene oxide, carbon nanotubes and boric acid were dispersed in deionized water, and the pH value was adjusted with ammonia water to prepare graphene slurry. The mass percentage of carbon nanotubes:boric acid:graphene oxide = 20:1.5:100, the mass percentage of slurry in graphene slurry was 4%, and the pH value was 7.

[0060] Preparation of graphene precursor film: The prepared graphene slurry was coated on one side of a polyarylene oxadiazole polymer film layer (140 μm thick) with a coating thickness of 5 mm. The film was dried in a ventilated environment at 60 °C for 4 hours to obtain the graphene precursor film.

[0061] Carbonization treatment: Under an argon atmosphere, the temperature is increased to 1100℃ at a heating rate of 20℃ / min, and held at 1100℃ for 2 hours to obtain a graphene foam film.

[0062] Graphitization treatment: Under an argon atmosphere, the temperature is increased to 3000℃ at a heating rate of 10℃ / min, and held at 3000℃ for 2 hours to obtain a graphene foam film.

[0063] Pressing process: The graphene foam film is repeatedly pressed 5 times under a pressure of 70MPa using a roller pressing device to obtain a graphene thermal conductive film.

[0064] Example 2

[0065] The difference between this and Example 1 is that the graphene slurry contains 3% by mass.

[0066] Example 3

[0067] The difference between this and Example 1 is that the graphene slurry contains 7% by mass.

[0068] Example 4

[0069] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 1:1.5:100.

[0070] Example 5

[0071] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 5:1.5:100.

[0072] Example 6

[0073] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 10:1.5:100.

[0074] Example 7

[0075] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 30:1.5:100.

[0076] Example 8

[0077] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 50:1.5:100.

[0078] Example 9

[0079] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 65:1.5:100.

[0080] Example 10

[0081] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 80:1.5:100.

[0082] Example 11

[0083] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 20:0.1:100.

[0084] Example 12

[0085] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 20:0.5:100.

[0086] Example 13

[0087] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 20:1.0:100.

[0088] Example 14

[0089] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 20:2.5:100.

[0090] Example 15

[0091] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 20:5.0:100.

[0092] Example 16

[0093] The difference between this and Example 1 is that in the graphene slurry, the ratio of carbon nanotubes: boric acid: graphene oxide is 20:10:100.

[0094] Example 17

[0095] The difference between this and Example 1 is that the graphene slurry contains no boric acid, and the ratio of carbon nanotubes to graphene oxide is 20:100.

[0096] Example 18

[0097] The difference between this and Example 1 is that the graphene slurry contains no carbon nanotubes, and the ratio of boric acid to graphene oxide is 1.5:100.

[0098] Example 19

[0099] Preparation of graphene slurry: A certain amount of graphene oxide, carbon nanotubes and boric acid were dispersed in deionized water, and the pH value was adjusted with ammonia water to prepare graphene slurry. The mass percentage of carbon nanotubes:boric acid:graphene oxide = 20:1.5:100, the mass percentage of slurry in graphene slurry was 4%, and the pH value was 7.

[0100] Preparation of graphene oxide film: The prepared graphene slurry was coated onto one side of polyester resin with a coating thickness of 5 mm. The coating was dried in a ventilated environment at 60°C for 4 hours to obtain graphene oxide film, and then the graphene oxide film was separated from the substrate.

[0101] Preparation of graphene precursor film: Graphene oxide film is stacked on a polyarylene oxadiazole polymer film layer.

[0102] Carbonization treatment: Under an argon atmosphere, the temperature is increased to 1100℃ at a heating rate of 20℃ / min, and held at 1100℃ for 2 hours to obtain a graphene foam film.

[0103] Graphitization treatment: Under an argon atmosphere, the temperature is increased to 3000℃ at a heating rate of 10℃ / min, and held at 3000℃ for 2 hours to obtain a graphene foam film.

[0104] Pressing process: The graphene foam film is repeatedly pressed 5 times under a pressure of 70MPa using a roller pressing device to obtain a graphene thermal conductive film.

[0105] Comparative Example 1

[0106] Preparation of graphene slurry: A certain amount of graphene oxide is dispersed in deionized water, and the pH value is adjusted with ammonia water to prepare graphene slurry. The mass percentage of slurry in the graphene slurry is 4%, and the pH value is 7.

[0107] Preparation of graphene oxide film: The prepared graphene slurry was coated onto one side of polyester resin with a coating thickness of 3 mm. The coating was dried in a ventilated environment at 60°C for 4 hours to obtain graphene oxide film, and then the graphene oxide film was separated from the substrate.

[0108] Carbonization treatment of graphene oxide film: Under an argon atmosphere, the temperature is increased to 1100℃ at a heating rate of 20℃ / min, and held at 1100℃ for 2 hours to obtain a carbonized graphene film.

[0109] Graphitization treatment of carbonized graphene film: Under an argon atmosphere, the temperature is increased to 3000℃ at a heating rate of 10℃ / min, and held at 3000℃ for 2 hours to obtain graphene foam film.

[0110] Pressing process: Two graphene foam films are stacked and rolled repeatedly 5 times under a pressure of 70MPa using a rolling press to obtain a graphene thermal conductive film.

[0111] Comparative Example 2: Direct carbonization and graphitization treatment of polyarylexadiazole fibers.

[0112] Carbonization treatment of polyarylexadiazole polymer membrane (140 μm thickness): Under argon atmosphere, the temperature was increased to 1100℃ at a heating rate of 20℃ / min and held at 1100℃ for 2 hours to obtain the polymer carbonized membrane.

[0113] Graphitization treatment of polymer carbonized film: Under an argon atmosphere, the temperature is increased to 3000℃ at a heating rate of 10℃ / min, and held at 3000℃ for 2 hours to obtain a polymer graphite foam film.

[0114] Pressing process: The polymer graphite foam film is repeatedly pressed 5 times under a pressure of 70MPa using a flat pressing device to obtain a polymer graphite thermal conductive film.

[0115] The graphene thermally conductive film samples from Examples 1 to 19, and Comparative Examples 1 and 2, were subjected to performance tests, and the test results are shown in Table 1. Thickness testing referenced standard CB / T6672-2001. Density testing referenced standard GB / T1033-2008. Peel strength testing referenced standard GB / T 2792-2014. Horizontal thermal conductivity testing referenced standards GB / T22588-2008 and ASTM E1461-13(2022). Longitudinal thermal conductivity testing referenced standard ASTM D 5470-17.

[0116] Table 1

[0117]

[0118]

[0119] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the detailed descriptions of other embodiments above, which will not be repeated here.

[0120] The basic concepts have been described above. Obviously, for those skilled in the art, the detailed disclosure above is merely illustrative and does not constitute a limitation of this application. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to this application. Such modifications, improvements, and corrections are suggested in this application, and therefore remain within the spirit and scope of the exemplary embodiments of this application.

[0121] The foregoing has provided a detailed description of a graphene thermal conductive film and its preparation method, as well as a smart terminal, provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a graphene thermally conductive film, characterized in that, Includes the following steps: A graphene precursor film is prepared, the graphene precursor film comprising a plurality of polymer film layers and a plurality of graphene oxide film layers, wherein the polymer film layers and the graphene oxide film layers are alternately stacked. The graphene precursor film was carbonized under a protective atmosphere to obtain a carbonized graphene film. Under a protective atmosphere, the carbonized graphene film is graphitized to obtain a graphene foam film. The obtained film is pressed to obtain the graphene thermally conductive film; The steps for preparing the graphene precursor film include: A graphene slurry is prepared, the graphene slurry comprising graphene oxide, a solvent, and a pH adjuster; The graphene slurry is coated on at least one side of the polymer film and dried to obtain the graphene precursor film; wherein the graphene slurry further includes carbon nanotubes and boric acid, the mass ratio of the carbon nanotubes to the graphene oxide is (1-100):100; the mass ratio of the boric acid to the graphene oxide is greater than or equal to 0.1% and less than 5%.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the carbon nanotubes to the graphene oxide is (10-30):

100.

3. The preparation method according to claim 1, characterized in that, The polymer film is selected from one or more of polyarylexadiazole, polyimide, polyamic acid, and polyacrylonitrile.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The mass ratio of boric acid to graphene oxide is (1-2.5):

100.

5. The preparation method according to claim 4, characterized in that, The steps for preparing the graphene slurry include: The graphene oxide, boric acid, and pH adjuster are dispersed in a solvent according to a preset ratio to prepare a graphene slurry. The mass percentage of the slurry in the graphene slurry is 2% to 7%, and the pH value of the graphene slurry is 5 to 10.

6. The preparation method according to claim 1, characterized in that, The process before carbonizing the graphene precursor film also includes: The graphene precursor film was left to stand at 100℃~400℃ for 0.5H~2H.

7. The preparation method according to claim 1, characterized in that, The carbonization temperature is 800℃~1500℃, and the carbonization time is 0.5H~5H; And / or, the graphitization treatment temperature is 2700℃~3200℃, and the graphitization treatment time is 0.5H~10H; And / or, the drying temperature is 40℃~105℃; And / or, the pressure of the pressing process is 10 MPa to 200 MPa; And / or, the solvent is selected from one or more of water, ethanol, N,N-dimethylformamide and N-methylpyrrolidone.

8. A graphene thermally conductive film, characterized in that, The graphene thermal conductive film is prepared by the method for preparing the graphene thermal conductive film according to any one of claims 1 to 7.

9. A smart terminal, characterized in that, The smart terminal includes a motherboard and the graphene thermal conductive film as described in claim 8, wherein the graphene thermal conductive film is used for heat dissipation of the motherboard.

Images