Intelligent equipment, graphene-carbon nanotube composite heat-conducting film and preparation method of graphene-carbon nanotube composite heat-conducting film
The graphene-carbon nanotube composite thermal conductivity film was prepared through high-speed dispersion and induced peeling treatment, which solved the problems of low thermal conductivity and poor heat dissipation uniformity in the prior art, achieved efficient heat dissipation performance and structural stability, simplified the preparation process and reduced costs.
Patent Information
- Application Number
- CN202411939396.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-05-06
AI Technical Summary
The existing composite thermal conductivity films of graphene and carbon nanotubes have problems such as low thermal conductivity, poor heat dissipation uniformity and insufficient structural stability during the preparation process. The preparation process is cumbersome and costly, which cannot meet the high heat dissipation needs of smart devices.
Carbon nanotubes, expanded graphite and water are mixed with high-speed dispersion treatment. The graphene layer is formed by inducing peeling, and then mixed with the binder and dispersed and defoamed to form a graphene-carbon nanotube thermal conductivity network to avoid surfactant and oxidation treatment, and simplify the preparation process.
A graphene-carbon nanotube composite thermal conductivity film with high thermal conductivity, good heat dissipation uniformity and excellent structural stability was prepared to meet the high heat dissipation needs of smart devices and improve the safety performance of the equipment.
Smart Images
Figure CN119931104A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of heat dissipation of electronic products, and in particular to an intelligent device, a graphene-carbon nanotube composite thermal conductive film and a preparation method thereof. Background Art
[0002] With the rapid development of communication and interconnection technology, the electronic product industry such as mobile phones and tablet computers has ushered in a new era of intelligence, lightness, and portability, which has led to higher requirements for mobile phone performance. When electronic products operate at high performance, they often generate a lot of heat. After verification by the upstream and downstream industries, it was found that in order to ensure the efficient operation of electronic products, the thermal conductivity of the added thermal conductive material must be higher than 1300W / (m·K).
[0003] As a new type of two-dimensional carbon nanomaterial, graphene has high thermal conductivity and has good application prospects in improving the heat dissipation problem of smart devices. Graphene thermal conductive films are mainly divided into physical graphene thermal conductive films and reduced oxide graphene thermal conductive films:
[0004] ① Physical method graphene thermal conductive film, graphite is used as raw material, and then graphene is prepared by ball milling, shear stripping, ultrasonic stripping and other methods, and then graphene and surfactant are dispersed in water to form a graphene dispersion, and finally a graphene thermal conductive film is made by vacuum filtration or coating. Since the physical method graphene thermal conductive film increases the dispersion effect of graphene by introducing surfactants, the surfactants will affect the phonon heat dissipation of graphene, reducing the thermal conductivity of the thermal conductive film, and the phonon conduction is hindered due to multiple heat dissipation phenomena in the vertical film direction, further reducing the heat transfer effect of the thermal conductive film, so that the thermal conductivity of the physical method graphene thermal conductive film is only 500-800W / (m·K), which cannot meet the high heat dissipation requirements of smart devices.
[0005] ②Redox graphene thermal conductive film, using graphite as raw material, using strong oxidants to prepare graphene oxide containing hydrophilic oxygen-containing functional groups, dispersing graphene oxide in water, and then using vacuum filtration, wet spinning, evaporation and blade coating to prepare graphene oxide film, and subjecting the graphene oxide film to high-temperature reduction and annealing processes according to the heat treatment process of carbonization and graphitization to prepare reduced graphene oxide thermal conductive film. The thermal conductivity of the reduced graphene oxide thermal conductive film prepared by this process can reach about 1350W / (m·K), but there will be residual oxidized functional groups in the reduction process, and the oxidation process will destroy the conjugated sp 2 Network, that is, the reduced graphene oxide thermal conductive film will be affected by the residual oxygen-containing functional groups and the destruction of the graphene structure, resulting in poor heat dissipation uniformity and structural stability of the reduced graphene oxide thermal conductive film. When used in smart devices, it is easy to cause local overtemperature, which will eventually lead to safety problems such as burning or even explosion of the smart devices, reducing the safety of the smart devices.
[0006] Since carbon nanotubes are a new type of carbon nanomaterial with excellent electrical, thermal and mechanical properties, there have been studies on the composite formation of graphene composite thermal conductive films by combining graphene oxide and carbon nanotubes. The preparation of graphene composite thermal conductive films generally involves first obtaining graphene oxide through an oxidation process, then uniformly dispersing carbon nanotubes and graphene oxide with the aid of surfactants, and then obtaining graphene composite thermal conductive films through a heat treatment reduction process after film formation. Although carbon nanotubes increase the heat transfer effect between graphene layers, the presence of surfactants will inhibit the further improvement of the thermal conductivity of the graphene composite thermal conductive film. At the same time, there will be residual oxidized functional groups in the reduction process, and the oxidation process will destroy the conjugated sp 2 Network, resulting in the graphene composite thermal conductive film still has the problems of poor heat dissipation uniformity and poor structural stability. When used in smart devices, it is easy to cause local overtemperature, which eventually leads to safety problems such as burning or even explosion of smart devices, reducing the safety of smart devices. In addition, the process flow of graphene composite thermal conductive film is cumbersome and costly.
[0007] Therefore, how to produce a thermally conductive film with high thermal conductivity, good heat dissipation uniformity and good structural stability while simplifying the preparation process and reducing production costs is a technical difficulty that urgently needs to be overcome. Summary of the invention
[0008] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a thermally conductive film with high thermal conductivity, good heat dissipation uniformity and good structural stability, while simplifying the preparation process and reducing production costs, an intelligent device, a graphene-carbon nanotube composite thermally conductive film and a preparation method thereof.
[0009] The purpose of this disclosure is achieved through the following technical solutions:
[0010] A method for preparing a graphene-carbon nanotube composite thermally conductive film comprises the following steps:
[0011] The carbon nanotubes, expanded graphite and water are mixed and then subjected to high-speed dispersion treatment to obtain an expanded graphite-carbon nanotube composite slurry;
[0012] Performing an induced exfoliation treatment on the expanded graphite-carbon nanotube composite slurry to obtain a graphene-carbon nanotube composite slurry;
[0013] The graphene-carbon nanotube composite slurry and the binder are mixed and then dispersed and degassed to obtain a graphene-carbon nanotube composite thermal conductive slurry;
[0014] The graphene-carbon nanotube composite thermal conductive slurry is subjected to film-forming treatment to obtain a graphene-carbon nanotube composite thermal conductive film.
[0015] In one embodiment, the specific operation steps of mixing carbon nanotubes, expanded graphite and water and then performing high-speed dispersion treatment are as follows:
[0016] The carbon nanotubes, the expanded graphite and water are added into a high-speed disperser for high-speed dispersion treatment to obtain the expanded graphite-carbon nanotube composite slurry.
[0017] In one embodiment, the specific operation steps of inducing exfoliation treatment on the expanded graphite-carbon nanotube composite slurry are:
[0018] The expanded graphite-carbon nanotube composite slurry is added into a homogenizer for induced exfoliation treatment to obtain the graphene-carbon nanotube composite slurry.
[0019] In one embodiment, the specific operation steps of mixing the graphene-carbon nanotube composite slurry and the binder and then performing dispersion and degassing treatment are as follows:
[0020] The graphene-carbon nanotube composite slurry and the binder are added into a centrifugal disperser for dispersion and degassing treatment to obtain the graphene-carbon nanotube composite thermal conductive slurry.
[0021] In one embodiment, the specific operation steps of film-forming the graphene-carbon nanotube composite thermal conductive slurry include:
[0022] Adding the graphene-carbon nanotube composite thermal conductive slurry into a coating machine for coating treatment to obtain a graphene-carbon nanotube composite thermal conductive slurry coating;
[0023] Adding the graphene-carbon nanotube thermal conductive slurry coating into a drying machine for curing treatment to obtain a graphene-carbon nanotube composite thermal conductive layer;
[0024] The graphene-carbon nanotube composite heat-conducting layer is subjected to calendering treatment by using a roller press to obtain the graphene-carbon nanotube composite heat-conducting film.
[0025] In one embodiment, the mass ratio of the carbon nanotubes, the expanded graphite and the deionized water is 1:(2-5):(94-97).
[0026] In one embodiment, the adhesive is any one of epoxy resin, acrylic resin and silicone resin.
[0027] In one of the embodiments, the mass ratio of the graphene-carbon nanotube composite slurry to the binder is 1:(0.5-1.5).
[0028] A graphene-carbon nanotube composite thermally conductive film is prepared by using the graphene-carbon nanotube composite thermally conductive film preparation method described in any of the above embodiments.
[0029] An intelligent device comprises the above-mentioned graphene-carbon nanotube composite thermal conductive film.
[0030] Compared with the prior art, the present invention has at least the following advantages:
[0031] 1. The carbon nanotubes and expanded graphite are fully mixed by high-speed dispersion treatment to form an expanded graphite-carbon nanotube composite slurry, and then the expanded graphite-carbon nanotube composite slurry is subjected to induced exfoliation treatment to exfoliate the expanded graphite into a plurality of graphene layers. At this time, the carbon nanotubes play a bridging role, and a plurality of graphene layers are connected in series to form a graphene-carbon nanotube thermal conductive network. Then, the graphene-carbon nanotube composite slurry and a binder are mixed and then subjected to dispersion and degassing treatment to make the graphene-carbon nanotube thermal conductive network evenly distributed in the graphene-carbon nanotube composite thermal conductive slurry. The graphene-carbon nanotube composite thermal conductive slurry after degassing has a good surface flatness after film-forming treatment to form a graphene-carbon nanotube composite thermal conductive film, so that the graphene-carbon nanotube composite thermal conductive film has a high thermal conductivity, good heat dissipation uniformity and excellent structural stability.
[0032] 2. The expanded graphite and carbon nanotubes are fully mixed by high-speed dispersion treatment without the intervention of surfactants, so as to avoid the situation that the surfactant affects the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film. Then, the graphite-carbon nanotube composite slurry is subjected to induced stripping treatment without additional oxidation and reduction treatment, so as to avoid the oxidation functional groups affecting the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film, and also avoid the conjugated sp of graphene during the oxidation process. 2 The network is destroyed, which can simplify the preparation process, reduce costs, and prepare a graphene-carbon nanotube composite thermally conductive film with higher thermal conductivity, better heat dissipation uniformity and better structural stability. The graphene-carbon nanotube composite thermally conductive film can meet the high heat dissipation requirements of smart devices, thereby improving the heat dissipation performance of smart devices while improving the safety performance of smart devices. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.
[0034] Figure 1This is a flow chart of a method for preparing a graphene-carbon nanotube composite thermal conductive film in one embodiment;
[0035] Figure 2 It is a distribution diagram of thermal conductivity data of Examples 1 to 12 and Comparative Examples 1 to 12;
[0036] Figure 3 This is a SEM electron microscope image of the graphene-carbon nanotube composite thermal conductive film of Example 1;
[0037] Figure 4 This is a thermal imaging image of the graphene-carbon nanotube composite thermal conductive film in the heat dissipation process of Example 1;
[0038] Figure 5 This is a thermal imaging image of the graphene-carbon nanotube composite thermal conductive film of Comparative Example 6 during the heat dissipation process;
[0039] Figure 6 This is a thermal imaging image of the reduced graphene oxide thermal conductive film in the heat dissipation process of Comparative Example 10;
[0040] Figure 7 This is a thermal imaging image of the graphene composite thermal conductive film in the heat dissipation process of Comparative Example 11;
[0041] Figure 8 This is a thermal imaging picture of the graphene-carbon nanotube composite thermal conductive film of comparative example 12 during the heat dissipation process. DETAILED DESCRIPTION
[0042] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.
[0043] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.
[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.
[0045] The present disclosure provides a method for preparing a graphene-carbon nanotube composite thermal conductive film, comprising the following steps: mixing carbon nanotubes, expanded graphite and water and performing high-speed dispersion treatment to obtain expanded graphite-carbon nanotube composite slurry. Performing induced exfoliation treatment on the expanded graphite-carbon nanotube composite slurry to obtain graphene-carbon nanotube composite slurry. Mixing the graphene-carbon nanotube composite slurry and a binder and performing dispersion and degassing treatment to obtain graphene-carbon nanotube composite thermal conductive slurry. Performing film-forming treatment on the graphene-carbon nanotube composite thermal conductive slurry to obtain a graphene-carbon nanotube composite thermal conductive film.
[0046] The above-mentioned graphene-carbon nanotube composite thermal conductive film preparation method comprises the following steps: high-speed dispersion treatment is used to fully mix carbon nanotubes and expanded graphite to form an expanded graphite-carbon nanotube composite slurry; the expanded graphite-carbon nanotube composite slurry is then subjected to an induced exfoliation treatment to exfoliate the expanded graphite into a plurality of graphene layers, at which point the carbon nanotubes play a bridging role, and a plurality of graphene layers are connected in series to form a graphene-carbon nanotube thermal conductive network; the graphene-carbon nanotube composite slurry is then mixed with a binder and subjected to a dispersion and degassing treatment to uniformly distribute the graphene-carbon nanotube thermal conductive network in the graphene-carbon nanotube composite thermal conductive slurry; the graphene-carbon nanotube composite thermal conductive slurry after degassing has a good surface flatness after film forming treatment to form a graphene-carbon nanotube composite thermal conductive film, so that the graphene-carbon nanotube composite thermal conductive film has a high thermal conductivity, good heat dissipation uniformity and excellent structural stability.
[0047] Furthermore, the expanded graphite and the carbon nanotubes are fully mixed by high-speed dispersion treatment without the intervention of surfactants, thereby avoiding the situation where the surfactant affects the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film. Then, the graphite-carbon nanotube composite slurry is subjected to induced stripping treatment without additional oxidation treatment and reduction treatment, thereby avoiding the oxidation functional groups from affecting the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film, and also avoiding the conjugated sp of graphene during the oxidation process. 2 The network is destroyed, which can simplify the preparation process, reduce costs, and prepare a graphene-carbon nanotube composite thermally conductive film with higher thermal conductivity, better heat dissipation uniformity and better structural stability. The graphene-carbon nanotube composite thermally conductive film can meet the high heat dissipation requirements of smart devices, thereby improving the heat dissipation performance of smart devices while improving the safety performance of smart devices.
[0048] See also Figure 1 In order to better understand the method for preparing the graphene-carbon nanotube composite thermally conductive film disclosed in the present invention, the method for preparing the graphene-carbon nanotube composite thermally conductive film is further explained below:
[0049] A method for preparing a graphene-carbon nanotube composite thermally conductive film according to an embodiment of the present invention comprises the following steps:
[0050] S100, carbon nanotubes, expanded graphite and water are mixed and then subjected to high-speed dispersion treatment to obtain expanded graphite-carbon nanotube composite slurry.
[0051] In this embodiment, carbon nanotubes, expanded graphite and water are mixed according to a mass ratio and then subjected to a high-speed dispersion treatment, so that the carbon nanotubes and expanded graphite can be fully mixed in the water to form a uniformly dispersed expanded graphite-carbon nanotube composite slurry. The uniform dispersion effect of expanded graphite and carbon nanotubes can be achieved without the use of a surfactant, thereby reducing cost output and avoiding the situation where the surfactant affects the improvement of thermal conductivity.
[0052] It is understandable that when the content of expanded graphite is too low, the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film will be insufficient due to the low content of graphene in the slurry after exfoliation, making it difficult to meet the high heat dissipation requirements of smart devices. However, when the content of expanded graphite is too high, the graphene content in the slurry after exfoliation is high, which will cause local graphene aggregation and fail to form a good graphene-carbon nanotube thermal conductive network structure, causing the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film to decrease.
[0053] Therefore, in one embodiment, the mass ratio of carbon nanotubes, expanded graphite and deionized water is 1:(2-5):(94-97). At this mass ratio, the expanded graphite and carbon nanotubes can be fully mixed, and the agglomeration of graphene after exfoliation can be reduced to form a good graphene-carbon nanotube thermal conductive network structure, thereby improving the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film. Furthermore, the mass ratio of carbon nanotubes, expanded graphite and deionized water is preferably 1:3:96, which can maximize the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film.
[0054] Further, in one embodiment, the specific operation steps of mixing carbon nanotubes, expanded graphite and water and then dispersing them at a high speed are as follows: adding carbon nanotubes, expanded graphite and water into a high-speed disperser for high-speed dispersion to obtain expanded graphite-carbon nanotube composite slurry. It should be noted that the high-speed rotation characteristics of the high-speed disperser are used to fully and evenly stir the carbon nanotubes and expanded graphite in water to increase the contact area between the expanded graphite and the carbon nanotubes, which helps to form a good graphene-carbon nanotube thermal conductive network structure with the carbon nanotubes after the expanded graphite is peeled off, thereby effectively improving the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film.
[0055] Further, in one embodiment, the speed of the high-speed disperser is 1000-2000 rpm, and the time of the high-speed dispersion treatment is 45-80 min. It is understood that the speed of the high-speed disperser is between 1000 and 2000 rpm to fully mix the expanded graphite and the carbon nanotubes, and the high-speed dispersion treatment needs to be controlled between 45 and 80 min to form a uniformly dispersed expanded graphite-carbon nanotube composite slurry.
[0056] S200, performing an induced exfoliation treatment on the expanded graphite-carbon nanotube composite slurry to obtain a graphene-carbon nanotube composite slurry.
[0057] In this embodiment, the expanded graphite is peeled off into a plurality of graphene layers and the graphene layers and carbon nanotubes are induced to form a graphene-carbon nanotube-graphene structure, thereby forming a good graphene-carbon nanotube thermal conductive network structure, thereby effectively improving the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film.
[0058] Further, in one of the embodiments, the specific operation steps of inducing exfoliation treatment of expanded graphite-carbon nanotube composite slurry are: adding the expanded graphite-carbon nanotube composite slurry into a homogenizer for induced exfoliation treatment to obtain a graphene-carbon nanotube composite slurry. It is understandable that the expanded graphite-carbon nanotube composite slurry is continuously cyclically pressurized by the homogenizer, so that the expanded graphite is exfoliated into a plurality of graphene layers, and the graphene is evenly distributed in the slurry, increasing the contact area between the graphene and the carbon nanotubes, and promoting the graphene and the carbon nanotubes to overlap into a good graphene-carbon nanotube thermal conductive network structure under pressure, so that the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film can be effectively improved.
[0059] It is understandable that when the pressure of the homogenizer is too low, the homogenization time will be increased while the particle size of the graphene-carbon nanotube composite slurry cannot be reduced, that is, the graphene will agglomerate and a good graphene-carbon nanotube thermal conductive network structure cannot be formed, which will reduce the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film. However, when the pressure of the homogenizer is too high, the particle size of the graphene-carbon nanotube composite slurry will be too small, resulting in insufficient overlap of the graphene-carbon nanotube thermal conductive network structure, which will reduce the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film.
[0060] Therefore, in one of the embodiments, the pressure value of the homogenizer is 20-80 MPa, the time of the induced stripping treatment is 20-40 min, and the particle size D50 of the graphene-carbon nanotube composite slurry is 5-30 μm. It can be understood that the particle size D50 of the graphene-carbon nanotube composite slurry is controlled between 5-30 μm, that is, a good graphene-carbon nanotube thermal conductive network structure is formed. For this reason, the pressure value of the homogenizer needs to be controlled between 20-80 MPa to ensure that the expanded graphite can be completely stripped while the graphene and carbon nanotubes are fully in contact, reducing the agglomeration of graphene, so that a good graphene-carbon nanotube thermal conductive network structure can be overlapped, thereby effectively improving the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film.
[0061] S300, mixing the graphene-carbon nanotube composite slurry and the binder and performing dispersion and degassing treatment to obtain the graphene-carbon nanotube composite thermal conductive slurry.
[0062] In this embodiment, the graphene-carbon nanotube composite slurry and the binder are mixed and dispersed, so that the graphene-carbon nanotube thermal conductive network structure can be evenly dispersed in the slurry, and multiple graphene-carbon nanotube thermal conductive network structures are connected in series by the binder, so that the heat dissipation uniformity and structural stability of the graphene-carbon nanotube composite thermal conductive film can be effectively improved. In addition, through the degassing treatment, the graphene-carbon nanotube composite thermal conductive slurry is evenly dispersed without generating bubbles, so that the flatness of the graphene-carbon nanotube composite thermal conductive slurry after film formation is better, and the bubbling phenomenon of the graphene-carbon nanotube composite thermal conductive film is avoided, which reduces the heat dissipation uniformity of the graphene-carbon nanotube composite thermal conductive film.
[0063] Further, in one of the embodiments, the specific operation steps of mixing the graphene-carbon nanotube composite slurry and the binder and then dispersing and degassing the slurry are as follows: adding the graphene-carbon nanotube composite slurry and the binder into a centrifugal disperser for dispersing and degassing to obtain the graphene-carbon nanotube composite thermal conductive slurry. It can be understood that by fully mixing the graphene-carbon nanotube composite slurry and the binder in the centrifugal disperser, the bubbles generated during the mixing process of the graphene-carbon nanotube composite slurry and the binder can be removed by centrifugal force, and at the same time, the graphene-carbon nanotube thermal conductive network structure is evenly dispersed in the slurry and connected in series through the binder, so that a bubble-free and evenly dispersed graphene-carbon nanotube composite thermal conductive slurry can be formed, so that the graphene-carbon nanotube composite thermal conductive film has a good flatness, thereby effectively improving the heat dissipation uniformity of the graphene-carbon nanotube composite thermal conductive film.
[0064] Further, in one of the embodiments, the speed of the centrifugal disperser is 100 to 1000 rpm, and the time of the dispersion and degassing treatment is 20 to 40 minutes. It is understandable that by controlling the speed of the centrifugal disperser between 100 and 1000 rpm, it is possible to ensure that the graphene-carbon nanotube composite slurry and the binder are fully mixed, so that the graphene-carbon nanotube thermal conductive network structure is evenly distributed in the slurry, and the binder is connected in series to improve the heat dissipation uniformity and structural stability of the graphene-carbon nanotube composite thermal conductive film. In addition, the dispersion and degassing treatment time is controlled at 20 to 40 minutes to ensure that the graphene-carbon nanotube composite thermal conductive slurry is free of bubbles and maintains good fluidity under the action of the centrifugal disperser, so that the graphene-carbon nanotube composite thermal conductive film has good flatness, and further improves the heat dissipation uniformity of the graphene-carbon nanotube composite thermal conductive film.
[0065] It is understandable that when the content of the binder is too low, the viscosity of the graphene-carbon nanotube composite thermal conductive slurry is too low, and the film cannot be formed in the subsequent film forming process. When the content of the binder is too high, the viscosity of the graphene-carbon nanotube composite thermal conductive slurry will increase, making it difficult to disperse the graphene-carbon nanotube composite thermal conductive slurry evenly in the centrifugal disperser, resulting in uneven dispersion of the graphene-carbon nanotube thermal conductive network structure in the slurry, thereby reducing the heat dissipation uniformity of the graphene-carbon nanotube composite thermal conductive film.
[0066] Therefore, in one of the embodiments, the mass ratio of the graphene-carbon nanotube composite slurry to the binder is 1:(0.5-1.5). It should be noted that by controlling the mass ratio of the graphene-carbon nanotube composite slurry to the binder to be between 1:(0.5-1.5), the graphene-carbon nanotube composite thermal conductive slurry is ensured to have a stable viscosity value, and the centrifugal disperser can be stirred, thereby ensuring that the graphene-carbon nanotube thermal conductive network structure can be evenly dispersed in the slurry, thereby ensuring that the graphene-carbon nanotube composite thermal conductive film has good heat dissipation uniformity.
[0067] Further, in one of the embodiments, the binder is any one of epoxy resin, acrylic resin and silicone resin. It is understandable that epoxy resin, acrylic resin and silicone resin all have good bonding properties, can increase the viscosity of graphene-carbon nanotube composite slurry, ensure that film can be formed, and also have excellent mechanical properties, so that the flexibility of graphene-carbon nanotube composite thermal conductive film is effectively improved. In addition, silicone resin is polysiloxane, and the molecular chain of polysiloxane contains silicon oxygen bond (Si-O), and the bond energy of this bond is high, so that the polysiloxane molecular chain has high thermal stability and chemical stability, and through the polysiloxane matrix multiple graphene-carbon nanotube thermal conductive network structures are connected in series, heat can be transferred faster, so that the thermal conductivity, heat dissipation uniformity and structural stability of the graphene-carbon nanotube composite thermal conductive film can be significantly improved.
[0068] S400, performing film-forming treatment on the graphene-carbon nanotube composite thermal conductive slurry to obtain a graphene-carbon nanotube composite thermal conductive film.
[0069] In this embodiment, the degassed graphene-carbon nanotube composite thermal conductive slurry is coated, dried and rolled in sequence to obtain a graphene-carbon nanotube composite thermal conductive film with good flatness, so that the graphene-carbon nanotube composite thermal conductive film has high thermal conductivity while having good heat dissipation uniformity and better structural stability, thereby being able to match the heat dissipation requirements of smart devices, thereby improving the heat dissipation performance and safety performance of smart devices.
[0070] Furthermore, in one embodiment, the specific operation steps of film-forming the graphene-carbon nanotube composite thermal conductive slurry include:
[0071] Adding the graphene-carbon nanotube composite thermal conductive slurry into a coating machine for coating treatment to obtain a graphene-carbon nanotube composite thermal conductive slurry coating;
[0072] The graphene-carbon nanotube thermal conductive slurry coating is added into a drying machine for curing treatment to obtain a graphene-carbon nanotube composite thermal conductive layer.
[0073] The graphene-carbon nanotube composite thermal conductive layer is subjected to calendering treatment by a roller press to obtain a graphene-carbon nanotube composite thermal conductive film.
[0074] It should be noted that by coating the graphene-carbon nanotube composite thermal conductive slurry in a coating machine with a certain thickness, a graphene-carbon nanotube composite thermal conductive slurry coating can be obtained, and then the graphene-carbon nanotube composite thermal conductive slurry coating is transferred to a drying machine for curing treatment to form a graphene-carbon nanotube composite thermal conductive layer, and finally a roller press is used to calender the graphene-carbon nanotube composite thermal conductive layer to extend the graphene-carbon nanotube composite thermal conductive layer into a graphene-carbon nanotube composite thermal conductive film.
[0075] In one embodiment, the thickness of the coater in the coater is 0.05-0.5 mm. It is understood that by introducing the graphene-carbon nanotube composite thermal conductive slurry into the coater of the coater, a graphene-carbon nanotube composite thermal conductive slurry coating with a thickness of 0.05-0.5 mm is formed.
[0076] It can be understood that the graphene-carbon nanotube composite thermal conductive slurry coating is cured by heating in the dryer, but when the temperature in the dryer is too low, it is difficult to completely dry the graphene-carbon nanotube composite thermal conductive slurry coating, resulting in the inability to effectively form the graphene-carbon nanotube composite thermal conductive film, while causing higher energy consumption. When the temperature in the dryer is too high, it will cause the binder to decompose and form gas that overflows from the film body, resulting in bubbling in the graphene-carbon nanotube composite thermal conductive film, reducing the flatness of the graphene-carbon nanotube composite thermal conductive film, and thereby reducing the heat dissipation uniformity of the graphene-carbon nanotube composite thermal conductive film. Therefore, in one of the embodiments, the temperature in the dryer is between 60 and 120°C. The temperature in the dryer is between 60 and 120°C, which can completely dry the graphene-carbon nanotube composite thermal conductive slurry coating, so that the graphene-carbon nanotube composite thermal conductive film can be effectively formed, while avoiding the decomposition of the binder, so that the graphene-carbon nanotube composite thermal conductive film has better flatness after film formation.
[0077] Furthermore, the graphene-carbon nanotube composite thermal conductive slurry coating has a low material density after curing, resulting in looseness between graphene layers. The graphene-carbon nanotube composite thermal conductive slurry coating is rolled by a roller press to improve the compactness of the graphene-carbon nanotube-graphene thermal conductive structure, so as to improve the graphene-carbon nanotube thermal conductive network structure, thereby improving the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film. However, the pressure value of the roller press is too low, resulting in the inability to effectively increase the material density, the graphene layers are still very loose, the graphene-carbon nanotube thermal conductive network structure is not perfect, and the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film is reduced. If the pressure value of the roller press is too high, the material density will be too high and cracks will appear, that is, the material will break, resulting in the destruction of the graphene-carbon nanotube thermal conductive network structure, thereby reducing the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film. Therefore, in one of the embodiments, the pressure value of the roller press is 20-60 MPa. By controlling the pressure value of the roller press between 20 and 60 MPa, the material density of the graphene-carbon nanotube composite thermally conductive film is increased, and the graphene-carbon nanotube-graphene thermally conductive structure becomes more compact. At the same time, material breakage can be avoided to perfect a good graphene-carbon nanotube thermally conductive network structure, thereby maximizing the thermal conductivity and structural stability of the graphene-carbon nanotube composite thermally conductive film.
[0078] The present disclosure also provides a graphene-carbon nanotube composite thermally conductive film, which is prepared by using the graphene-carbon nanotube composite thermally conductive film preparation method described in any of the above embodiments.
[0079] In the present embodiment, the graphene-carbon nanotube composite thermally conductive film prepared by the graphene-carbon nanotube composite thermally conductive film preparation method disclosed herein has high thermal conductivity, good heat dissipation uniformity and excellent structural stability, so that the graphene-carbon nanotube composite thermally conductive film can improve the heat dissipation performance of the smart device when applied to the smart device to match the high heat dissipation requirements at high power output, and at the same time avoid the occurrence of local high temperature phenomenon, thereby improving the safety performance of the smart device.
[0080] The present disclosure also provides a smart device, comprising the above-mentioned graphene-carbon nanotube composite thermal conductive film.
[0081] In this embodiment, the graphene-carbon nanotube composite thermally conductive film disclosed herein has high thermal conductivity, good heat dissipation uniformity and excellent structural stability, which can improve the heat dissipation performance of smart devices to match the high heat dissipation requirements during high power output, and at the same time can avoid the occurrence of local high temperature phenomena, thereby improving the safety performance of smart devices.
[0082] Examples are listed below, but it should be noted that the following examples do not exhaust all possible situations, and the materials used in the following examples can be obtained from commercial channels unless otherwise specified.
[0083] Example 1
[0084] Step 1: adding carbon nanotubes and expanded graphite to deionized water in a mass ratio of carbon nanotubes: expanded graphite: deionized water of 1:3:96, and dispersing the carbon nanotubes and expanded graphite in a high-speed disperser at a speed of 1500 rpm for 60 minutes until the carbon nanotubes and expanded graphite are evenly dispersed to obtain an expanded graphite-carbon nanotube composite slurry;
[0085] Step 2: Transfer the expanded graphite-carbon nanotube composite slurry to a homogenizer for induced exfoliation at a homogenization pressure of 70 MPa, and wait until the slurry particle size D50 reaches 30 μm to obtain a graphene-carbon nanotube composite slurry;
[0086] Step 3: Add the graphene-carbon nanotube composite slurry and the silicone resin into a disperser at a mass ratio of 1:1, and perform dispersion and degassing treatment at a speed of 500 rpm. Mix for 30 minutes until the slurry is dispersed without bubbles and maintains good fluidity, thereby obtaining a graphene-carbon nanotube composite thermal conductive slurry;
[0087] Step 4: Use a coater to coat the graphene-carbon nanotube composite thermal conductive slurry with a thickness of 0.1 mm to obtain a graphene-carbon nanotube composite thermal conductive slurry coating, use a drying machine to cure the graphene-carbon nanotube composite thermal conductive slurry coating at 80° C. to obtain a graphene-carbon nanotube composite thermal conductive layer, and use a roller press to calender the graphene-carbon nanotube composite thermal conductive layer at 55 MPa to obtain a graphene-carbon nanotube composite thermal conductive film.
[0088] Example 2
[0089] The difference from Example 1 is:
[0090] Step 1: Add carbon nanotubes and expanded graphite into deionized water at a mass ratio of carbon nanotubes: expanded graphite: deionized water of 1:2:97.
[0091] Example 3
[0092] The difference from Example 1 is:
[0093] Step 1: Add carbon nanotubes and expanded graphite into deionized water at a mass ratio of carbon nanotubes: expanded graphite: deionized water of 1:4:95.
[0094] Example 4
[0095] The difference from Example 1 is:
[0096] Step 1: Add carbon nanotubes and expanded graphite into deionized water at a mass ratio of carbon nanotubes: expanded graphite: deionized water of 1:5:94.
[0097] Example 5
[0098] The difference from Example 1 is:
[0099] Step 2: Transfer the expanded graphite-carbon nanotube composite slurry to a homogenizer for induced exfoliation at a homogenization pressure of 20 MPa.
[0100] Example 6
[0101] The difference from Example 1 is:
[0102] Step 2: Transfer the expanded graphite-carbon nanotube composite slurry to a homogenizer for induced exfoliation at a homogenization pressure of 80 MPa.
[0103] Example 7
[0104] The difference from Example 1 is:
[0105] Step 3: Add the graphene-carbon nanotube composite slurry and epoxy resin into the disperser in a mass ratio of 1:1.
[0106] Example 8
[0107] The difference from Example 1 is:
[0108] Step 3: Add the graphene-carbon nanotube composite slurry and acrylic resin into the disperser in a mass ratio of 1:1.
[0109] Example 9
[0110] The difference from Example 1 is:
[0111] Step 4: Use a drying machine to cure the graphene-carbon nanotube composite thermal conductive slurry coating at 60°C.
[0112] Example 10
[0113] The difference from Example 1 is:
[0114] Step 4: Use a drying machine to cure the graphene-carbon nanotube composite thermal conductive slurry coating at 120°C.
[0115] Embodiment 11
[0116] The difference from Example 1 is:
[0117] Step 4: Use a roller press to perform calendering treatment on the graphene-carbon nanotube composite thermal conductive layer at 20 MPa.
[0118] Example 12
[0119] The difference from Example 1 is:
[0120] Step 4: Use a roller press to perform calendering treatment on the graphene-carbon nanotube composite thermal conductive layer at 60 MPa.
[0121] Comparative Example 1
[0122] The difference from Example 1 is:
[0123] Step 1: Add carbon nanotubes and expanded graphite into deionized water at a mass ratio of carbon nanotubes: expanded graphite: deionized water of 1:0.5:98.5.
[0124] Comparative Example 2
[0125] The difference from Example 1 is:
[0126] Step 1: Add carbon nanotubes and expanded graphite into deionized water at a mass ratio of carbon nanotubes: expanded graphite: deionized water of 1:8:91.
[0127] Comparative Example 3
[0128] The difference from Example 1 is:
[0129] Step 2: Transfer the expanded graphite-carbon nanotube composite slurry to a homogenizer for induced exfoliation at a homogenization pressure of 10 MPa.
[0130] Comparative Example 4
[0131] The difference from Example 1 is:
[0132] Step 2: Transfer the expanded graphite-carbon nanotube composite slurry to a homogenizer for induced exfoliation at a homogenization pressure of 100 MPa.
[0133] Comparative Example 5
[0134] The difference from Example 1 is:
[0135] Step 4: Use a drying machine to cure the graphene-carbon nanotube composite thermal conductive slurry coating at 40°C.
[0136] Comparative Example 6
[0137] The difference from Example 1 is:
[0138] Step 4: Use a drying machine to cure the graphene-carbon nanotube composite thermal conductive slurry coating at 150°C.
[0139] Comparative Example 7
[0140] The difference from Example 1 is:
[0141] Step 4: Use a roller press to perform calendering treatment on the graphene-carbon nanotube composite thermal conductive layer at 5 MPa.
[0142] Comparative Example 8
[0143] The difference from Example 1 is:
[0144] Step 4: Use a roller press to perform calendering treatment on the graphene-carbon nanotube composite thermal conductive layer at 80 MPa.
[0145] Comparative Example 9
[0146] Graphite is used as raw material, and graphene is prepared by ball milling, shear exfoliation, ultrasonic exfoliation and other methods. Graphene and surfactant are then dispersed in water to form a graphene dispersion, and finally a graphene thermal conductive film is made by vacuum filtration or coating.
[0147] Comparative Example 10
[0148] Graphite is used as raw material and a strong oxidant is used to prepare graphene oxide containing hydrophilic oxygen-containing functional groups. The graphene oxide is dispersed in water, and then a graphene oxide film is prepared by vacuum filtration, wet spinning, evaporation and blade coating. The graphene oxide film is subjected to high-temperature reduction and annealing processes according to the heat treatment process of carbonization and graphitization to obtain a reduced graphene oxide thermal conductive film.
[0149] Comparative Example 11
[0150] Graphite is used as raw material and a strong oxidant is used to prepare graphene oxide containing hydrophilic oxygen-containing functional groups. Carbon nanotubes and graphene oxide are dispersed in water with the assistance of surfactants. Then, a graphene oxide composite film is prepared by vacuum filtration, wet spinning, evaporation and scraping. The graphene oxide composite film is subjected to high-temperature reduction and annealing processes according to the heat treatment process of carbonization and graphitization to obtain a graphene composite thermal conductive film.
[0151] Comparative Example 12
[0152] The difference from Example 1 is:
[0153] Step 3: Add the graphene-carbon nanotube composite slurry and the silicone resin into the disperser in a mass ratio of 1:2.
[0154] Comparative Example 13
[0155] The difference from Example 1 is:
[0156] Step 3: Add the graphene-carbon nanotube composite slurry and the silicone resin into the disperser at a mass ratio of 1:0.1.
[0157] Comparative Example 13 cannot form a film and cannot measure the thermal conductivity. The thermal conductivity of the thermally conductive films of Examples 1 to 12 and Comparative Examples 1 to 12 is tested. The test results are shown in Tables 1 and Figure 2 .
[0158] Table 1
[0159] Thermal conductivity W / (m·K) Example 1 1489.94 Example 2 1443.16 Example 3 1428.59 Example 4 1322.37 Example 5 1317.43 Example 6 1350.39 Example 7 1321.28 Example 8 1358.40 Example 9 1373.84 Example 10 1309.37 Embodiment 11 1323.91 Example 12 1334.64 Comparative Example 1 1257.93 Comparative Example 2 1164.89 Comparative Example 3 998.34 Comparative Example 4 1024.87 Comparative Example 5 949.68 Comparative Example 6 894.61 Comparative Example 7 793.58 Comparative Example 8 809.31 Comparative Example 9 496.22 Comparative Example 10 1314.65 Comparative Example 11 986.94 Comparative Example 12 1082.97 Comparative Example 13 / (Cannot test)
[0160] From Table 1 and Figure 2 It can be seen that by comparing the data of Example 1, Example 2, Example 3 and Example 4, when the mass ratio of carbon nanotubes, expanded graphite and deionized water is 1: (2-5): (94-97), the content of expanded graphite increases with the increasing trend of 2-5, and the corresponding thermal conductivity of the graphene-carbon nanotube composite thermal conductive film first increases and then decreases. When the mass proportion of expanded graphite is 3, the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film is the largest, which also shows that the mass ratio of carbon nanotubes, expanded graphite and deionized water is 1: 3: 96, which can maximize the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film. Further, as shown in the data of Comparative Example 1, when the content of expanded graphite is too low, the thermal conductivity of the graphene-carbon nanocomposite thermal conductive film will be insufficient due to the low content of graphene in the slurry after stripping, and it cannot match the high heat dissipation requirements of smart devices. Furthermore, as shown in the data of Comparative Example 2, when the content of expanded graphite is too high, local graphene agglomeration will occur due to the high content of graphene in the slurry after exfoliation, and a good graphene-carbon nanotube thermal conductive network structure cannot be formed, which reduces the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film and cannot match the high heat dissipation requirements of smart devices.
[0161] From Table 1 and Figure 2It can be seen that by comparing the data of Example 5 and Example 6, the pressure value of the homogenizer is between 20 and 80 MPa, and a graphene-carbon nanotube composite thermally conductive film with higher thermal conductivity, better heat dissipation uniformity and better structural stability can be obtained. Further, as shown in the data of Comparative Example 3, when the pressure value of the homogenizer is less than 20 MPa, the particle size of the graphene-carbon nanotube composite slurry cannot be reduced, that is, the graphene agglomerates, and a good graphene-carbon nanotube thermally conductive network structure cannot be formed, so that the thermal conductivity of the graphene-carbon nanotube composite thermally conductive film decreases. Further, as shown in the data of Comparative Example 4, when the pressure value of the homogenizer is greater than 80 MPa, the particle size of the graphene-carbon nanotube composite slurry will be too small, resulting in insufficient overlap of the graphene-carbon nanotube thermally conductive network structure, reducing the thermal conductivity of the graphene-carbon nanotube composite thermally conductive film. It can be seen that the pressure value of the homogenizer is between 20 and 80 MPa, which ensures that the expanded graphite can be completely peeled off while the graphene and carbon nanotubes are fully in contact, reducing the agglomeration of graphene, so that a good graphene-carbon nanotube thermal conductive network structure can be overlapped, thereby effectively improving the thermal conductivity and heat dissipation uniformity of the graphene-carbon nanotube composite thermal conductive film.
[0162] From Table 1 and Figure 2 It can be seen that by comparing the data of Example 1, Example 6 and Example 7, the combination of silicone values with graphene and carbon nanotubes can maximize the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film, which also shows that the binder is preferably silicone resin.
[0163] From Table 1 and Figure 2 It can be seen that by comparing the data of Example 1, Example 9 and Example 10, the temperature of the drying machine is between 60°C and 120°C, and a graphene-carbon nanotube composite thermally conductive film with higher thermal conductivity, better heat dissipation uniformity and better structural stability can be obtained. Further, as shown in the data of Comparative Example 5, when the temperature of the drying machine is less than 60°C, the curing time and energy consumption will be increased, while the thermal conductivity of the graphene-carbon nanotube composite thermally conductive film after film formation will be reduced, that is, the graphene-carbon nanotube composite thermally conductive film cannot be effectively and completely formed, and the thermal conductivity of the graphene-carbon nanotube composite thermally conductive film will be reduced. Further, as shown in the data of Comparative Example 6, when the temperature of the drying machine is greater than 120°C, the thermal conductivity and heat dissipation uniformity of the graphene-carbon nanotube composite thermal conductive film will be reduced. Specifically, the binder will decompose above 120°C, forming gas that overflows from the film body, causing bubbling of the graphene-carbon nanotube composite thermal conductive film, reducing the flatness of the graphene-carbon nanotube composite thermal conductive film. At the same time, the decomposition of the binder also affects the perfection of the graphene-carbon nanotube thermal conductive network structure, thereby reducing the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film. Please refer to Figure 4 and Figure 5Compared with the thermal imaging image of Example 1, the temperature color distribution in the thermal imaging image of Comparative Example 6 is uneven, which is easy to cause local high temperature when applied to smart devices, reducing the safety performance of smart devices. It can be seen that the graphene-carbon nanotube composite thermal conductive slurry coating can be completely dried, so that the graphene-carbon nanotube composite thermal conductive film can be effectively formed, while avoiding the decomposition of the binder, so that the graphene-carbon nanotube composite thermal conductive film has good flatness after film formation, and improves the thermal conductivity and heat dissipation uniformity of the graphene-carbon nanotube composite thermal conductive film.
[0164] From Table 1 and Figure 2 It can be seen that by comparing the data of Example 1, Example 11 and Example 12, the pressure value of the roller press is between 20 and 60 MPa, and a graphene-carbon nanotube composite thermal conductive film with higher thermal conductivity, better heat dissipation uniformity and better structural stability can be obtained. Further, as shown in the data of Comparative Example 7, when the pressure value of the roller press is less than 20 MPa, the material density is relatively small, resulting in looseness between the graphene layers, and the graphene-carbon nanotube thermal conductive network structure is not perfect, which reduces the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film. Further, as shown in the data of Comparative Example 8, when the pressure value of the roller press is greater than 60 MPa, the material density is too high and cracks appear, that is, the material breaks, resulting in the destruction of the graphene-carbon nanotube thermal conductive network structure, which reduces the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film. It can be seen that the pressure value of the roller press is between 20 and 60 MPa, which increases the material density of the graphene-carbon nanotube composite thermal conductive film and makes the graphene-carbon nanotube-graphene thermal conductive structure more compact. At the same time, it can avoid material breakage to perfect a good graphene-carbon nanotube thermal conductive network structure, thereby maximizing the thermal conductivity and structural stability of the graphene-carbon nanotube composite thermal conductive film.
[0165] From Table 1 and Figure 2 It can be seen that by comparing the data of Example 1, Comparative Example 9, Comparative Example 10 and Comparative Example 11, the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film prepared by the method for preparing the graphene-carbon nanotube composite thermal conductive film disclosed in the present invention is significantly higher than that of the physical method graphene thermal conductive film, the redox graphene thermal conductive film and the traditional graphene composite thermal conductive film. Figure 4 and Figure 7Although the thermal conductivity of the reduced graphene oxide thermal conductive film of comparative example 11 is relatively high, there are many areas in the thermal imaging image of comparative example 11 where the temperature colors are inconsistent and unevenly distributed, while the temperature colors in the thermal imaging image of embodiment 1 are relatively consistent and evenly distributed, that is, the heat dissipation uniformity of the graphene-carbon nanotube disclosed in the present invention is significantly better than that of the reduced graphene oxide thermal conductive film. This also shows that the preparation method of the graphene-carbon nanotube composite thermal conductive film disclosed in the present invention can avoid the influence of surfactants and oxidized functional groups, so that the graphene-carbon nanotube composite thermal conductive film has higher thermal conductivity, better heat dissipation uniformity and better structural stability.
[0166] From Table 1 and Figure 2 It can be seen from the comparison of the data of Example 1, Comparative Example 12 and Comparative Example 13 that when the content of the binder is too high, the viscosity of the graphene-carbon nanotube composite thermal conductive slurry will increase, making it difficult to disperse the graphene-carbon nanotube composite thermal conductive slurry evenly in the centrifugal disperser, resulting in uneven dispersion of the graphene-carbon nanotube thermal conductive network structure in the slurry, thereby reducing the heat dissipation uniformity of the graphene-carbon nanotube composite thermal conductive film. For details, please refer to Figure 4 and Figure 8 , the temperature color in the thermal imaging image of Example 1 is relatively consistent and evenly distributed, while in the thermal imaging image of Comparative Example 12, there are some areas where the temperature color is inconsistent and unevenly distributed. As shown in the data of Comparative Example 13, when the content of the binder is too low, the viscosity of the graphene-carbon nanotube composite thermal conductive slurry is too low, and a film cannot be formed during the subsequent film forming process. This also shows that the mass ratio of the graphene-carbon nanotube composite slurry and the binder is controlled between 1: (0.5~1.5), ensuring that the graphene-carbon nanotube composite thermal conductive slurry has a stable viscosity value, which can make the centrifugal disperser stir, thereby ensuring that the graphene-carbon nanotube thermal conductive network structure can be evenly dispersed in the slurry, and then ensuring that the graphene-carbon nanotube composite thermal conductive film has good heat dissipation uniformity.
[0167] Compared with the prior art, the present invention has at least the following advantages:
[0168] 1. The carbon nanotubes and expanded graphite are fully mixed by high-speed dispersion treatment to form an expanded graphite-carbon nanotube composite slurry, and then the expanded graphite-carbon nanotube composite slurry is subjected to induced exfoliation treatment to exfoliate the expanded graphite into a plurality of graphene layers. At this time, the carbon nanotubes play a bridging role, and a plurality of graphene layers are connected in series to form a graphene-carbon nanotube thermal conductive network. Then, the graphene-carbon nanotube composite slurry and a binder are mixed and then subjected to dispersion and degassing treatment to make the graphene-carbon nanotube thermal conductive network evenly distributed in the graphene-carbon nanotube composite thermal conductive slurry. The graphene-carbon nanotube composite thermal conductive slurry after degassing has a good surface flatness after film-forming treatment to form a graphene-carbon nanotube composite thermal conductive film, so that the graphene-carbon nanotube composite thermal conductive film has a high thermal conductivity, good heat dissipation uniformity and excellent structural stability.
[0169] 2. The expanded graphite and carbon nanotubes are fully mixed by high-speed dispersion treatment without the intervention of surfactants, so as to avoid the situation that the surfactant affects the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film. Then, the graphite-carbon nanotube composite slurry is subjected to induced stripping treatment without additional oxidation and reduction treatment, so as to avoid the oxidation functional groups affecting the thermal conductivity of the graphene-carbon nanotube composite thermal conductive film, and also avoid the conjugated sp of graphene during the oxidation process. 2 The network is destroyed, which can simplify the preparation process, reduce costs, and prepare a graphene-carbon nanotube composite thermally conductive film with higher thermal conductivity, better heat dissipation uniformity and better structural stability. The graphene-carbon nanotube composite thermally conductive film can meet the high heat dissipation requirements of smart devices, thereby improving the heat dissipation performance of smart devices while improving the safety performance of smart devices.
[0170] The above-mentioned embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the disclosed patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the disclosed patent shall be subject to the attached claims.
Claims
1. A method for preparing a graphene-carbon nanotube composite thermally conductive film, characterized in that: The steps include: The carbon nanotubes, expanded graphite and water are mixed and then subjected to high-speed dispersion treatment to obtain an expanded graphite-carbon nanotube composite slurry; Performing an induced exfoliation treatment on the expanded graphite-carbon nanotube composite slurry to obtain a graphene-carbon nanotube composite slurry; The graphene-carbon nanotube composite slurry and the binder are mixed and then dispersed and degassed to obtain a graphene-carbon nanotube composite thermal conductive slurry; The graphene-carbon nanotube composite thermal conductive slurry is subjected to film-forming treatment to obtain a graphene-carbon nanotube composite thermal conductive film.
2. The method for preparing the graphene-carbon nanotube composite thermally conductive film according to claim 1, characterized in that: The specific steps of mixing carbon nanotubes, expanded graphite and water for high-speed dispersion treatment are as follows: The carbon nanotubes, the expanded graphite and water are added into a high-speed disperser for high-speed dispersion treatment to obtain the expanded graphite-carbon nanotube composite slurry.
3. The method for preparing the graphene-carbon nanotube composite thermally conductive film according to claim 1, characterized in that: The specific operation steps of inducing exfoliation treatment on the expanded graphite-carbon nanotube composite slurry are as follows: The expanded graphite-carbon nanotube composite slurry is added into a homogenizer for induced exfoliation treatment to obtain the graphene-carbon nanotube composite slurry.
4. The method for preparing the graphene-carbon nanotube composite thermally conductive film according to claim 1, characterized in that: The specific operation steps of mixing the graphene-carbon nanotube composite slurry and the binder and then performing dispersion and degassing treatment are as follows: The graphene-carbon nanotube composite slurry and the binder are added into a centrifugal disperser for dispersion and degassing treatment to obtain the graphene-carbon nanotube composite thermal conductive slurry.
5. The method for preparing the graphene-carbon nanotube composite thermally conductive film according to claim 1, characterized in that: The specific operation steps of film-forming the graphene-carbon nanotube composite thermal conductive slurry include: Adding the graphene-carbon nanotube composite thermal conductive slurry into a coating machine for coating treatment to obtain a graphene-carbon nanotube composite thermal conductive slurry coating; Adding the graphene-carbon nanotube thermal conductive slurry coating into a drying machine for curing treatment to obtain a graphene-carbon nanotube composite thermal conductive layer; The graphene-carbon nanotube composite heat-conducting layer is subjected to calendering treatment by using a roller press to obtain the graphene-carbon nanotube composite heat-conducting film.
6. The method for preparing the graphene-carbon nanotube composite thermally conductive film according to claim 1, characterized in that: The mass ratio of the carbon nanotubes, the expanded graphite and the deionized water is 1:(2-5):(94-97).
7. The method for preparing the graphene-carbon nanotube composite thermally conductive film according to claim 1, characterized in that: The adhesive is any one of epoxy resin, acrylic resin and silicone resin.
8. The method for preparing the graphene-carbon nanotube composite thermal conductive film according to claim 1, characterized in that: The mass ratio of the graphene-carbon nanotube composite slurry to the binder is 1:(0.5-1.5).
9. A graphene-carbon nanotube composite thermal conductive film, characterized in that: The graphene-carbon nanotube composite thermally conductive film is prepared by the method for preparing the graphene-carbon nanotube composite thermally conductive film according to any one of claims 1 to 8.
10. A smart device, characterized in that: It includes the graphene-carbon nanotube composite thermal conductive film as described in claim 9.