Graphene heat dissipation film and preparation method thereof

Abstract

The invention relates to a graphene heat dissipation film and a preparation method thereof. The preparation method of the graphene heat dissipation film comprises the following steps: preparing mixed slurry containing graphene oxide and a defect repairing agent; performing film forming treatment on the mixed slurry to obtain a first film; carrying out carbonization treatment, graphitization treatment and calendaring treatment on the first thin film to obtain a second thin film; forming a radiation heat dissipation layer on the second thin film to obtain a graphene heat dissipation film; wherein the graphene oxide comprises at least two of first graphene oxide, second graphene oxide and third graphene oxide; the transverse size of the first graphene oxide is greater than that of the second graphene oxide; the transverse size of the second graphene oxide is greater than that of the third graphene oxide; the defect repairing agent comprises at least one of glucose, citric acid, citrate and vitamin C. The graphene heat dissipation film has the advantages of being low in structural defect, high in production yield, diversified in heat dissipation mechanism and excellent in heat dissipation performance.

Description

Technical Field

[0001] The present application relates to the field of thermal management technology, and in particular to a graphene heat dissipation film and a preparation method thereof. Background Art

[0002] With the rapid development of 5G communications, big data, and artificial intelligence technologies, electronic products are developing in the direction of miniaturization, thinness, multi-functions, and high performance, making the internal structure of electronic products more compact, the integration of components is getting higher and higher, and the power consumption and heat generation are constantly increasing. If too much heat cannot be removed in time, it will seriously affect the overall performance and service life of the equipment. According to research, more than 55% of electronic devices fail due to excessive device temperature. When the operating temperature of components reaches 70℃~80℃, the reliability of the equipment will decrease by 5% for every 1℃ increase; if the temperature increases by 10℃~20℃, the failure rate will increase by 100%. Therefore, there is an urgent need for an efficient thermal management system to ensure the operating efficiency, safety, reliability, stability, and durability of electronic equipment.

[0003] The most effective way to solve the heat dissipation problem is to use materials with better thermal conductivity to transfer the heat generated by the internal components of electronic equipment to the external heat sink in a timely manner, thereby reducing its operating temperature. As an emerging heat dissipation material, graphene heat dissipation film has excellent properties such as high thermal conductivity, high heat flux, good flexibility, light weight, and low thermal expansion coefficient. It can be used as a heat sink in electronic components to evenly disperse the heat generated by the heat source. It has outstanding application advantages in eliminating local hot spots, smoothing temperature gradients, and changing the direction of heat flow. It has great potential for low-cost, large-scale industrial production and is the most promising heat dissipation material in the field of thermal management. However, the heat dissipation effect of graphene heat dissipation film prepared by traditional methods is poor, which limits its application in the field of thermal management. Summary of the invention

[0004] Based on this, it is necessary to provide a graphene heat dissipation film and a preparation method thereof to solve the problem of poor heat dissipation effect of the graphene heat dissipation film prepared by the traditional method.

[0005] The above-mentioned purpose of the present application is achieved through the following technical solutions:

[0006] In a first aspect of the present application, a method for preparing a graphene heat dissipation film is provided, comprising the following steps: preparing a mixed slurry containing graphene oxide and a defect repairing agent;

[0007] Performing film-forming treatment on the mixed slurry to obtain a first film;

[0008] Carrying out carbonization, graphitization and calendering treatments on the first film to obtain a second film;

[0009] forming a radiation heat dissipation layer on the second film to obtain a graphene heat dissipation film;

[0010] Wherein, the graphene oxide includes at least two of a first graphene oxide, a second graphene oxide and a third graphene oxide;

[0011] The lateral size of the first graphene oxide is greater than the lateral size of the second graphene oxide;

[0012] The lateral size of the second graphene oxide is greater than the lateral size of the third graphene oxide;

[0013] The defect repairing agent includes at least one of glucose, citric acid, citrate and vitamin C.

[0014] In one embodiment, the lateral size of the first graphene oxide is 0.1 μm to 3.0 μm;

[0015] The lateral size of the second graphene oxide is 50nm~100nm;

[0016] The lateral size of the third graphene oxide is less than 50 nm.

[0017] In one embodiment, the mass ratio of the first graphene oxide, the second graphene oxide and the third graphene oxide is 1:(0.1-1):(0-1).

[0018] In one embodiment, the thickness of the graphene oxide is 0.3 nm to 4 nm.

[0019] In one embodiment, the ratio of the atomic percentage of carbon element to the atomic percentage of oxygen element in the graphene oxide is 1.6-3.0.

[0020] In one embodiment, the mass ratio of the graphene oxide to the defect repairing agent is 10:(1~5).

[0021] In one embodiment, the carbonization treatment temperature is 600°C to 1000°C, and the time is 2h to 5h;

[0022] The graphitization treatment is carried out under a protective atmosphere at a temperature of 1500° C. to 2500° C. for a time of 2 h to 30 h.

[0023] In one embodiment, the thickness of the second film is 10 μm to 80 μm, and the density is 1.5 g / cm 3 ~2.2g / cm 3 .

[0024] In one embodiment, forming a radiation heat dissipation layer on the second film includes the following steps: spraying a radiation heat dissipation coating on the second film to form the radiation heat dissipation layer.

[0025] In one embodiment, the radiation heat dissipation coating includes one or more of a polyvinylidene fluoride-hexafluoropropylene solution, a first mixed solution containing an inorganic carbon material, and a second mixed solution containing nano-oxides.

[0026] In a second aspect of the present application, a graphene heat dissipation film is provided, which is prepared by the method for preparing the graphene heat dissipation film as described above.

[0027] This application has at least the following beneficial effects:

[0028] The present application uses a compound of graphene oxide of different lateral sizes to fill the gaps of large-sized graphene with small-sized graphene oxide with smaller holes and wrinkles, thereby preparing a first film with fewer intrinsic defects. A defect repair agent is added to the mixed slurry, which is selected from organic substances such as glucose, citric acid, citrate and vitamin C. It will be completely decomposed into carbon during the carbonization process, and the structural defects of the first film are repaired, thereby improving the production yield and thermal conductivity and heat dissipation performance, and reducing energy consumption and preparation costs. At the same time, a radiation heat dissipation layer is formed on the second film, which not only plays a role in coating repair, but also makes the heat conduction and heat radiation during its operation match each other to achieve the effect of synergistic heat dissipation. Therefore, the graphene heat dissipation film prepared in the present application has the advantages of low structural defects, high production yield, diverse heat dissipation mechanisms, and excellent heat dissipation performance, and has a very broad application prospect in the field of thermal management. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more completely understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0030] Figure 1 is a schematic diagram of a process for preparing a graphene heat dissipation film in an embodiment;

[0031] Figure 2 This is an AFM microscopic morphology image of the first graphene oxide of Example 1;

[0032] Figure 3 is an AFM thickness image of the first graphene oxide of Example 1;

[0033] Figure 4This is an AFM microscopic morphology image of the second graphene oxide of Example 1;

[0034] Figure 5 This is a SEM image of the front side of the second film prepared in Example 1;

[0035] Figure 6 This is a SEM image of the cross section of the second film prepared in Example 1. DETAILED DESCRIPTION

[0036] In order to facilitate the understanding of the present application, the present application is further described in detail below in conjunction with specific embodiments. However, the present application 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 understanding of the disclosure of the present application more thorough and comprehensive.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0038] In the present application, the meaning of "and / or" includes any and all combinations of one or more related listed items. "At least one" means more than one, such as one, two and more than two. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layer" means at least two layers, such as two layers, three layers, etc., unless otherwise clearly and specifically defined. In the description of the present application, "several" means at least one, such as one, two, etc., unless otherwise clearly and specifically defined.

[0039] When a numerical range is disclosed in this application, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed in this application should be understood to include any and all subranges included therein.

[0040] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may also include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0041] In this application, "above" or "below" includes the number itself. For example, "1 below" includes 1.

[0042] The temperature parameters in this application, unless otherwise specified, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0043] In the present application, room temperature refers to indoor temperature, normal temperature or general temperature. Generally speaking, the range of room temperature can be any one of the following temperature intervals: 23°C ± 2°C, 25°C ± 5°C or 20°C ± 5°C.

[0044] the term

[0045] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0046] Graphene oxide dimensions: Graphene oxide is a two-dimensional material, whose dimensions in the plane direction are usually called lateral dimensions, and its dimension in the direction perpendicular to the plane is called thickness.

[0047] At present, the heat sinks in electronic devices generally use metal thermal conductive materials such as copper, silver and aluminum, which have disadvantages such as poor mechanical properties and high density. On the one hand, they increase the total weight of the heat dissipation system, which is not conducive to the lightweight and miniaturization of the equipment; on the other hand, the problem that metal is difficult to stretch and bend also limits its application in complex heat dissipation components, such as folding smartphones, laptops and spacecraft.

[0048] Carbon-based film materials have the advantages of low density, high thermal conductivity, low thermal expansion coefficient and good chemical stability. They are fast and efficient heat conduction materials, especially suitable for heat dissipation of small space and high heat flux density components. They play an important role in consumer electronics, communication equipment, power batteries, aerospace and other fields. Common carbon-based film materials include diamond film, graphite film and graphene film. Among them, diamond film has high hardness and brittleness, difficult processing and high production cost. The raw material of graphite film is polyimide film (PI film), which is difficult to produce. Graphene is the two-dimensional material with the highest known thermal conductivity. As an emerging heat dissipation material, graphene heat dissipation film has excellent characteristics such as high thermal conductivity, high heat flux, good flexibility, light weight and low thermal expansion coefficient. It can be used as a heat sink in electronic components to evenly disperse the heat generated by the heat source. It has outstanding application advantages in eliminating local hot spots, smoothing temperature gradients and changing the direction of heat flow. It has great potential for low-cost and large-scale industrial production and is the most promising heat dissipation material in the field of thermal management.

[0049] A report disclosed a method for preparing a graphene heat dissipation film: artificial graphite powder, graphene oxide slurry and a stripping agent are mixed evenly and then stripped to obtain a mixed slurry; the mixed slurry is degassed and then coated on a substrate, and then dried, peeled, carbonized, graphitized and rolled to obtain a graphene heat dissipation film. This preparation method can effectively improve the overall thermal conductivity and uniformity of the graphene heat dissipation film, but structural defects are easily generated during the preparation of the graphene heat dissipation film, thereby reducing the production yield and thermal conductivity and heat dissipation performance of the graphene heat dissipation film, and increasing energy consumption and preparation and cost.

[0050] This is because the main raw material of graphene heat dissipation film is graphene oxide powder, which is not a material with a completely single number of layers, a single lateral size, and a single thickness. In fact, it is a type of material mixed with graphene oxide of different lateral sizes and thicknesses. Its thickness, lateral size, and thickness have a wide distribution range, large structural differences, and relatively poor uniformity. Therefore, it is easy to produce structural defects in the processes of dispersion, coating, carbonization, and graphitization, thereby affecting the improvement of the performance of the graphene heat dissipation film. At the same time, in the design and production process of traditional graphene heat dissipation films, they often focus on the lateral (i.e., in-plane) thermal conductivity or uniform heat dissipation of graphene thermal conductive films, and ignore their heat dissipation and radiation heat dissipation capabilities in the thickness direction, resulting in a single heat dissipation mechanism of the graphene heat dissipation film, resulting in a situation where the lateral thermal conductivity of the graphene heat dissipation film is high, but the heat dissipation effect is not ideal.

[0051] Based on this, the present application provides a graphene heat dissipation film and a preparation method thereof to solve the problem of poor heat dissipation effect of the graphene heat dissipation film prepared by the traditional method.

[0052] See also Figure 1, which is a schematic diagram of a process for preparing a graphene heat dissipation film in an embodiment. Figure 1 As shown, the method for preparing the graphene heat dissipation film comprises the following steps:

[0053] S100: preparing a mixed slurry containing graphene oxide and a defect repairing agent;

[0054] S200: performing film-forming treatment on the mixed slurry to obtain a first film;

[0055] S300: performing carbonization treatment, graphitization treatment and calendering treatment on the first film to obtain a second film;

[0056] S400: forming a radiation heat dissipation layer on the second film to obtain a graphene heat dissipation film;

[0057] Wherein, the graphene oxide includes at least two of a first graphene oxide, a second graphene oxide and a third graphene oxide;

[0058] The lateral dimension of the first graphene oxide is greater than the lateral dimension of the second graphene oxide;

[0059] The lateral size of the second graphene oxide is greater than the lateral size of the third graphene oxide;

[0060] The defect repairing agent includes at least one of glucose, citric acid, citrate and vitamin C.

[0061] The present application uses a compound of graphene oxide of different lateral sizes to fill the gaps of large-sized graphene with small-sized graphene oxide with smaller holes and wrinkles, thereby preparing a first film with fewer intrinsic defects. A defect repair agent is added to the mixed slurry, which is selected from organic substances such as glucose, citric acid, citrate and vitamin C. It will be completely decomposed into carbon during the carbonization process, and the structural defects of the first film are repaired, thereby improving the production yield and thermal conductivity and heat dissipation performance, and reducing energy consumption and preparation costs. At the same time, a radiation heat dissipation layer is formed on the second film, which not only plays a role in coating repair, but also makes the heat conduction and heat radiation during its operation match each other to achieve the effect of synergistic heat dissipation. Therefore, the graphene heat dissipation film prepared in the present application has the advantages of low structural defects, high production yield, diverse heat dissipation mechanisms, and excellent heat dissipation performance, and has a very broad application prospect in the field of thermal management.

[0062] The following is a detailed description of the preparation method of the graphene heat dissipation film in a step-by-step manner.

[0063] S100: preparing a mixed slurry containing graphene oxide and a defect repairing agent.

[0064] This application uses graphene oxide (GO) as the main raw material for graphene heat dissipation film. GO is easy to dissolve and modify and has good compatibility with polymers. The oxygen-containing functional groups such as -COOH and -OH on GO can be cross-linked to form a graphene oxide film (i.e., the first film). The preparation process is relatively simple and the cost is low.

[0065] Optionally, the lateral size of the first graphene oxide is 0.1 μm to 3.0 μm;

[0066] The lateral size of the second graphene oxide is 50nm~100nm;

[0067] The lateral size of the third graphene oxide is less than 50 nm.

[0068] By optimizing the lateral dimensions of graphene oxide and reasonably restricting and compounding the lateral dimensions of the three graphene oxides, the small-sized graphene oxide has a better filling effect on the large-sized graphene oxide, thereby obtaining the first film with fewer intrinsic defects.

[0069] As an example, the lateral size of the first graphene oxide includes, but is not limited to, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3.0 μm. In some specific examples, the typical lateral size of the first graphene oxide is 0.35 μm.

[0070] As an example, the lateral size of the second graphene oxide includes, but is not limited to, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, or 100 nm.

[0071] As an example, a lateral size of the third graphene oxide includes, but is not limited to, 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, or 50 nm.

[0072] Optionally, the mass ratio of the first graphene oxide, the second graphene oxide and the third graphene oxide is 1:(0.1~1):(0~1).

[0073] As an example, the mass ratio of the first graphene oxide and the second graphene oxide includes but is not limited to: 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1; the mass ratio of the first graphene oxide and the third graphene oxide includes but is not limited to 1:0, 1:0.01, 1:0.05, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1.

[0074] Optionally, the thickness of graphene oxide is 0.3nm~4nm, including but not limited to: 0.3nm, 0.5nm, 0.8nm, 1nm, 1.5nm, 2nm, 2.5nm, 3nm, 3.5nm or 4nm, and can be further optionally 0.8nm~2nm.

[0075] In the present application, the thickness of graphene oxide is controlled within the range of 0.3 nm to 4 nm, which can improve the uniformity of graphene oxide and achieve better filling effect between graphene oxides of different lateral sizes.

[0076] In the present application, by regulating and compounding the thickness of graphene oxide, the structural differences of graphene oxide can be further reduced, and the filling effect between graphene oxides of different lateral sizes can be improved, so that the first film has fewer structural defects and higher intrinsic density.

[0077] Optionally, the ratio of atomic percentage of carbon element to oxygen element (C / O) in graphene oxide is 1.6-3.0, including but not limited to: 1.6, 1.7, 1.8, 1.9, 2, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9 or 3.

[0078] In the present application, by regulating the atomic percentage ratio of carbon element and oxygen element in graphene oxide, it can be ensured that it has sufficient oxygen-containing functional groups for cross-linking reaction, thereby obtaining a first film with better density.

[0079] Optionally, the mass ratio of graphene oxide to the defect repair agent is 10:(1~5), including but not limited to: 10:1, 10:1.5, 10:2, 10:2.5, 10:3, 10:3.5, 10:4, 10:4.5 or 10:5.

[0080] It can be understood that the defect repair agents in this application are all small molecules, and the molecular structure does not contain N elements or other heteroatoms. They can be removed under mild conditions after defect repair, and the process is simple. The defect repair agent can be selected from any one of glucose, citric acid, citrate and vitamin C, or can be selected from a combination of at least two of glucose, citric acid, citrate and vitamin C, including but not limited to: a combination of glucose and citric acid, a combination of glucose and citrate, a combination of glucose and vitamin C, a combination of citric acid and citrate, a combination of citric acid and vitamin C and vitamin C, a combination of glucose, citric acid and citrate, a combination of glucose, citric acid and vitamin C, a combination of glucose, citric acid and vitamin C, a combination of glucose, citrate and vitamin C, a combination of citric acid, citrate and vitamin C, a combination of glucose, citric acid, citrate and vitamin C. Wherein, citrate can be sodium citrate or potassium citrate. Further optionally, the defect repair agent is glucose.

[0081] Optionally, the mixed slurry further includes additives such as dispersants and defoamers to improve dispersibility and uniformity.

[0082] Optionally, the solvent in the mixed slurry includes one or more of water, methanol, ethanol and isopropanol, and further water. The water may be tap water, industrial water, distilled water, reverse osmosis water, deionized water, pure water and ultrapure water, and further deionized water or pure water.

[0083] Optionally, the preparation method of the mixed slurry includes the following steps: mixing graphene oxide and a solvent, performing a first mechanical stirring and a first ultrasonic dispersion to obtain graphene oxide slurry; mixing graphene oxide slurry and a defect repairing agent, performing a second mechanical stirring and a second ultrasonic dispersion to obtain a mixed slurry. Wherein, the mass fraction of graphene oxide in the graphene oxide slurry is 0.1% to 8%, including but not limited to: 0.1%, 0.2%, 0.5%, 0.8%, 1%, 2%, 3%, 4%, 5%, 6%, 7% or 8%. The rotation speeds of the first mechanical stirring and the second mechanical stirring are each independently 1000rpm~2000rpm, including but not limited to: 1000rpm, 1100rpm, 1200rpm, 1300rpm, 1400rpm, 1500rpm, 1600rpm, 1700rpm, 1800rpm, 1900rpm or 2000rpm; the time of the first mechanical stirring and the second mechanical stirring is each independently 1h~3h, including but not limited to: 1h, 1.2h, 1.5h, 1.8h, 2h, 2.2h, 2.5h, 2.8h or 3h; the time of the first ultrasonic dispersion and the second ultrasonic dispersion is each independently 0.5h~2h, including but not limited to: 0.5h, 0.8h, 1h, 1.2h, 1.5h, 1.8h or 2h.

[0084] S200: performing film-forming treatment on the mixed slurry to obtain a first thin film.

[0085] Optionally, the film forming process includes the following steps: forming a wet film from the mixed slurry by a coating method or a filtering method, and removing the solvent in the wet film by a drying process.

[0086] In the mixed slurry, there is a certain π-π conjugation effect between graphene oxides of different lateral sizes, so that small-sized graphene oxide can be adsorbed in the gaps of large-sized graphene oxide and promote filling and assembly during the film formation process, thereby forming a first thin film with few intrinsic defects and high intrinsic density.

[0087] As an example, the coating method includes one or more of blade coating, spin coating, brush coating, spray coating and slit coating, and further blade coating can be selected. The filtering method includes one or more of ordinary filtering, suction filtration and filter press, and further suction filtration can be selected.

[0088] Optionally, the drying temperature is 50°C to 95°C, and the drying time is 2h to 5h. As an example, the drying temperature may be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, or 95°C; and the drying time may be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, or 5h.

[0089] In the present application, drying is performed at 50°C to 95°C, so that the water or solvent such as ethanol in the wet film can be evaporated, and the oxygen-containing functional groups such as -COOH and -OH on the surface of the graphene oxide can undergo cross-linking reaction to form a continuous and dense first film.

[0090] S300: performing carbonization treatment, graphitization treatment and calendering treatment on the first film to obtain a second film.

[0091] Optionally, the temperature of the carbonization treatment is 600°C to 1000°C, and the time is 2h to 5h. As an example, the temperature of the carbonization treatment can be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C or 1000°C; the time of the carbonization treatment can be 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h.

[0092] This application performs carbonization treatment at 600℃~1000℃, which, on the one hand, removes oxygen-containing functional groups such as -COOH and -OH in graphene oxide, and on the other hand, completely decomposes defect repair agents such as glucose into carbon, thereby forming a layer of amorphous carbon on the surface of the film. While the carbon content is increased, the electrical conductivity and thermal conductivity are also significantly improved. The removal conditions of the defect repair agent are mild and leave no residue, which can improve product yield and thermal conductivity and heat dissipation performance, and reduce energy consumption and preparation costs.

[0093] Optionally, the graphitization treatment is carried out under a protective atmosphere at a temperature of 1500°C to 2500°C for a time of 2h to 30h. As an example, the protective atmosphere includes one or more of nitrogen, helium, argon, neon and xenon; the temperature of the graphitization treatment may be 1500°C, 1600°C, 1700°C, 1800°C, 1900°C, 2000°C, 2100°C, 2200°C, 2300°C, 2400°C or 2500°C; the time of the graphitization treatment may be 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h or 30h.

[0094] The present application performs graphitization treatment at 1500°C to 2500°C, which can convert the carbonized graphene oxide into a graphite structure, so that the interlayer spacing of the graphene oxide is reduced and the carbon atoms are arranged more orderly, thereby having higher crystallinity and better electrical conductivity and thermal conductivity.

[0095] Optionally, the second film has a thickness of 10 μm to 80 μm and a density of 1.8 g / cm 3 ~2.2g / cm 3 As an example, the thickness of the second film may be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm or 80 μm, and the density may be 1.8 g / cm 3 , 1.9g / cm 3 , 2g / cm 3 , 2.1g / cm 3 or 2.2g / cm 3 .

[0096] Optionally, the calendering process is performed using a roller press or a calender.

[0097] S400: forming a radiation heat dissipation layer on the second film to obtain a graphene heat dissipation film;

[0098] Optionally, forming a radiation heat dissipation layer on the second film comprises the following steps: spraying a radiation heat dissipation coating on the second film to form the radiation heat dissipation layer.

[0099] It can be understood that the second film has a relatively parallel first surface and a second surface, wherein the first surface is close to the heat source and can be attached to the heat source, the second surface is away from the heat source, and the radiation heat dissipation layer is located on the second surface of the second film. During the operation of the graphene heat dissipation film, the heat conduction of the second film and the heat radiation of the radiation heat dissipation layer are matched to achieve a synergistic heat dissipation effect.

[0100] The present application uses a radiation heat dissipation coating with high emissivity to be sprayed on the second film.

[0101] Optionally, the radiant heat dissipation coating includes one or more of a polyvinylidene fluoride (PVDF)-hexafluoropropylene (HFP) solution, a first mixed solution containing an inorganic carbon material, and a second mixed solution containing nano-oxides.

[0102] Optionally, in the PVDF-HFP solution, the mass fraction of PVDF-HFP is 25% to 50%. Wherein, PVDF-HFP refers to a copolymer of vinylidene fluoride and hexafluoropropylene, and the preparation method of the PVDF-HFP solution is as follows: dissolving PVDF-HFP in acetone, adding water, and obtaining a PVDF-HFP solution.

[0103] Optionally, the inorganic carbon material includes one or more of graphene, carbon nanotubes, graphene oxide, carbon fiber and fullerene, and can further be graphene and carbon nanotubes; the mass fraction of the inorganic carbon material in the first mixed liquid is 0.1%~1%; the solvent of the first mixed liquid includes one or more of water, methanol, ethanol and isopropanol.

[0104] Optionally, the nano-oxide includes one or more of nano-silicon dioxide, nano-titanium dioxide, nano-zinc dioxide and nano-magnesium oxide, and nano-silicon dioxide may be further selected; the particle size of the nano-oxide is 10nm~1000nm, including but not limited to: 10nm, 20nm, 50nm, 80nm, 100nm, 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm; the mass fraction of the nano-oxide in the second mixed liquid is 30%~40%; the solvent of the second mixed liquid includes one or more of water, methanol, ethanol and isopropanol.

[0105] Optionally, the thickness of the radiation heat dissipation layer is 0.1 μm to 1 μm. As an example, the thickness of the radiation heat dissipation layer can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm.

[0106] In a second aspect of the present application, a graphene heat dissipation film is provided, which is prepared by the method for preparing the graphene heat dissipation film as described above.

[0107] Optionally, the thickness of the graphene heat dissipation film is 10 μm to 80 μm. As an example, the thickness of the graphene heat dissipation film may be 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm or 80 μm.

[0108] Optionally, the density of the graphene heat dissipation film is 1.5 g / cm 3 ~2.2g / cm 3 As an example, the density of the graphene heat dissipation film can be 1.5g / cm 3 , 1.6g / cm 3 , 1.7g / cm 3 , 1.8g / cm 3 , 1.9g / cm 3 , 2g / cm 3 , 2.1g / cm 3 or 2.2g / cm 3 .

[0109] Optionally, the lateral thermal diffusion coefficient of the graphene heat dissipation film is 550 mm 2 / s~1080mm 2 As an example, the lateral thermal diffusion coefficient of the graphene heat dissipation film can be 550 mm 2 / s、600mm 2 / s、700mm 2 / s、800mm 2 / s、900mm 2 / s、1000mm 2 / s or 1080mm 2 / s.

[0110] Optionally, the thermal conductivity of the graphene heat dissipation film is ≥ 1400 W / (m·K). As an example, the thermal conductivity of the graphene heat dissipation film may be 1400 W / (m·K), 1450 W / (m·K), 1500 W / (m·K), 1550 W / (m·K), 1600 W / (m·K), 1650 W / (m·K) or 1700 W / (m·K).

[0111] The following is further described in conjunction with specific embodiments and comparative examples. The raw materials involved in the following specific embodiments and comparative examples, unless otherwise specified, can all be commercially available, the instruments used, unless otherwise specified, can all be commercially available, and the processes involved, unless otherwise specified, are all routinely selected by those skilled in the art.

[0112] Example 1

[0113] Please refer to Table 1, the preparation method of the graphene heat dissipation film of this embodiment is as follows:

[0114] (1) Graphene oxide was added to water, mechanically stirred at a rotation speed of 1500 rpm for 2 h, and ultrasonically fractionated for 1 h to obtain graphene oxide slurry; a defect repair agent was added to the graphene oxide slurry, mechanically stirred at a rotation speed of 1500 rpm for 2 h, and ultrasonically fractionated for 1 h to obtain a mixed slurry.

[0115] Wherein, the graphene oxide is selected from the first graphene and the second graphene in a mass ratio of 1:0.1;

[0116] The lateral size of the first graphene oxide is 0.1 μm to 3.0 μm;

[0117] The lateral size of the second graphene oxide is 50nm~100nm;

[0118] The thickness of graphene oxide is 0.334nm~4nm;

[0119] Glucose is selected as the defect repair agent, and the mass ratio of graphene oxide to the defect repair agent is 10:2.

[0120] (2) The mixed slurry is evenly coated with a coating machine to form a wet film, and then dried at 70° C. to evaporate the solvent, thereby obtaining a first thin film.

[0121] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then the first film is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then the second film is calendered using a calendering machine to obtain a second film.

[0122] (4) The second film has a first surface and a second surface that are parallel to each other, and the second surface is away from the heat source; a radiation heat dissipation coating is sprayed on the second surface, and after drying, a radiation heat dissipation layer with a thickness of 0.5 μm is formed, thereby preparing a graphene heat dissipation film.

[0123] Among them, the radiation heat dissipation coating uses PVDF-HFP solution.

[0124] Example 2

[0125] This embodiment is basically the same as embodiment 1, except that in step (4), the radiation heat dissipation coating is a first mixed liquid containing an inorganic carbon material, the inorganic carbon material includes graphene and carbon nanotubes, the solvent of the first mixed liquid is ethanol, and the thickness of the radiation heat dissipation layer obtained by spraying is 0.5 μm.

[0126] Example 3

[0127] This embodiment is basically the same as embodiment 1, except that in step (4), the radiation heat dissipation coating is a second mixed liquid containing nano oxides, the nano oxides are nano silicon dioxide with a particle size of 50 nm, the solvent of the second mixed liquid is water, and the thickness of the radiation heat dissipation layer obtained by spraying is 1 μm.

[0128] Example 4

[0129] This embodiment is basically the same as Embodiment 1, except that in step (1), the mass ratio of graphene oxide to defect repair agent glucose is 10:1.

[0130] Example 5

[0131] This embodiment is basically the same as Embodiment 1, except that in step (1), the mass ratio of graphene oxide to defect repair agent glucose is 10:5.

[0132] Example 6

[0133] This embodiment is basically the same as Embodiment 1, except that: in step (1), citric acid is used as the defect repair agent, and the mass ratio of graphene oxide to the defect repair agent citric acid is 10:2.

[0134] Example 7

[0135] This embodiment is substantially the same as embodiment 1, except that: in step (1), the graphene oxide is selected from the first graphene and the third graphene in a mass ratio of 1:0.1;

[0136] The lateral size of the first graphene oxide is 0.1 μm to 3.0 μm;

[0137] The lateral size of the third graphene oxide is less than 50 nm;

[0138] The thickness of graphene oxide is 0.334nm~4nm;

[0139] Example 8

[0140] This embodiment is substantially the same as embodiment 1, except that: in step (1), the graphene oxide is selected from the first graphene, the second graphene and the third graphene in a mass ratio of 1:0.1:0.1;

[0141] The lateral size of the first graphene oxide is 0.1 μm to 3.0 μm;

[0142] The lateral size of the second graphene oxide is 50nm~100nm;

[0143] The lateral size of the third graphene oxide is less than 50 nm;

[0144] The thickness of graphene oxide is 0.334nm~4nm.

[0145] Example 9

[0146] This embodiment is substantially the same as embodiment 1, except that: in step (1), the graphene oxide is selected from the fourth graphene and the fifth graphene in a mass ratio of 1:0.1;

[0147] The lateral size of the fourth graphene oxide is 100 μm to 150 μm;

[0148] The lateral size of the fifth graphene oxide is 5 μm to 20 μm;

[0149] The thickness of graphene oxide is 5nm~15nm.

[0150] Comparative Example 1

[0151] The preparation method of the graphene heat dissipation film of this comparative example is as follows:

[0152] (1) Graphene oxide was added to water, mechanically stirred at 1500 rpm for 2 h, and ultrasonicated for 1 h to obtain graphene oxide slurry.

[0153] The graphene oxide is a first graphene having a lateral size of 0.1 μm to 3.0 μm and a thickness of 0.334 nm to 4 nm;

[0154] (2) The graphene oxide slurry is evenly coated with a coating machine to form a wet film, and then dried at 70° C. to evaporate the solvent, thereby obtaining a first thin film.

[0155] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then the first film is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then the second film is calendered using a calender to obtain a graphene heat dissipation film.

[0156] Comparative Example 2

[0157] The preparation method of the graphene heat dissipation film of this comparative example is as follows:

[0158] (1) Graphene oxide was added to water, mechanically stirred at a rotation speed of 1500 rpm for 2 h, and ultrasonically fractionated for 1 h to obtain graphene oxide slurry; a defect repair agent was added to the graphene oxide slurry, mechanically stirred at a rotation speed of 1500 rpm for 2 h, and ultrasonically fractionated for 1 h to obtain a mixed slurry.

[0159] The graphene oxide is a first graphene having a lateral size of 0.1 μm to 3.0 μm and a thickness of 0.334 nm to 4 nm;

[0160] Glucose is selected as the defect repair agent, and the mass ratio of graphene oxide to the defect repair agent is 10:1.

[0161] (2) The mixed slurry is evenly coated with a coating machine to form a wet film, and then dried at 70° C. to evaporate the solvent, thereby obtaining a first thin film.

[0162] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then the first film is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then the second film is calendered using a calender to obtain a graphene heat dissipation film.

[0163] Comparative Example 3

[0164] The preparation method of the graphene heat dissipation film of this comparative example is as follows:

[0165] (1) Graphene oxide was added to water, mechanically stirred at a rotation speed of 1500 rpm for 2 h, and ultrasonically fractionated for 1 h to obtain graphene oxide slurry; a defect repair agent was added to the graphene oxide slurry, mechanically stirred at a rotation speed of 1500 rpm for 2 h, and ultrasonically fractionated for 1 h to obtain a mixed slurry.

[0166] The graphene oxide is a first graphene having a lateral size of 0.1 μm to 3.0 μm and a thickness of 0.334 nm to 4 nm;

[0167] Glucose is selected as the defect repair agent, and the mass ratio of graphene oxide to the defect repair agent is 10:1.

[0168] (2) The mixed slurry is evenly coated with a coating machine to form a wet film, and then dried at 70° C. to evaporate the solvent, thereby obtaining a first thin film.

[0169] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then the first film is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then the second film is calendered using a calendering machine to obtain a second film.

[0170] (4) The second film has a first surface and a second surface that are parallel to each other, and the second surface is away from the heat source; a radiation heat dissipation coating is sprayed on the second surface, and after drying, a radiation heat dissipation layer with a thickness of 0.5 μm is formed, thereby preparing a graphene heat dissipation film.

[0171] Among them, the radiation heat dissipation coating uses PVDF-HFP solution.

[0172] Comparative Example 4

[0173] The preparation method of the graphene heat dissipation film of this comparative example is as follows:

[0174] (1) Graphene oxide was added to water, mechanically stirred at 1500 rpm for 2 h, and ultrasonicated for 1 h to obtain graphene oxide slurry.

[0175] Wherein, the graphene oxide is selected from the first graphene and the second graphene in a mass ratio of 1:0.2;

[0176] The lateral size of the first graphene oxide is 0.1 μm to 3.0 μm;

[0177] The lateral size of the second graphene oxide is 50nm~100nm;

[0178] The thickness of graphene oxide is 0.334nm~4nm;

[0179] (2) The graphene oxide slurry is evenly coated with a coating machine to form a wet film, and then dried at 70° C. to evaporate the solvent, thereby obtaining a first thin film.

[0180] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then the first film is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then the second film is calendered using a calender to obtain a graphene heat dissipation film.

[0181] Comparative Example 5

[0182] This comparative example is substantially the same as comparative example 4, except that: in step (1), the graphene oxide is selected from the first graphene and the third graphene in a mass ratio of 1:0.2;

[0183] The lateral size of the first graphene oxide is 0.1 μm to 3.0 μm;

[0184] The lateral size of the third graphene oxide is less than 50 nm;

[0185] The thickness of graphene oxide is 0.334nm~4nm;

[0186] Comparative Example 6

[0187] This comparative example is substantially the same as comparative example 4, except that: in step (1), the graphene oxide is selected from the first graphene, the second graphene and the third graphene in a mass ratio of 1:0.2:0.2;

[0188] The lateral size of the first graphene oxide is 0.1 μm to 3.0 μm;

[0189] The lateral size of the second graphene oxide is 50nm~100nm;

[0190] The lateral size of the third graphene oxide is less than 50 nm;

[0191] The thickness of graphene oxide is 0.334nm~4nm.

[0192] Comparative Example 7

[0193] The preparation method of the graphene heat dissipation film of this comparative example is as follows:

[0194] (1) Graphene oxide was added to water, mechanically stirred at a rotation speed of 1500 rpm for 2 h, and ultrasonically fractionated for 1 h to obtain graphene oxide slurry; a defect repair agent was added to the graphene oxide slurry, mechanically stirred at a rotation speed of 1500 rpm for 2 h, and ultrasonically fractionated for 1 h to obtain a mixed slurry.

[0195] Wherein, the graphene oxide is selected from the first graphene and the second graphene in a mass ratio of 1:0.2;

[0196] The lateral size of the first graphene oxide is 0.1 μm to 3.0 μm;

[0197] The lateral size of the second graphene oxide is 50nm~100nm;

[0198] The thickness of graphene oxide is 0.334nm~4nm;

[0199] Glucose is selected as the defect repair agent, and the mass ratio of graphene oxide to the defect repair agent is 10:1.

[0200] (2) The mixed slurry is evenly coated with a coating machine to form a wet film, and then dried at 70° C. to evaporate the solvent, thereby obtaining a first thin film.

[0201] (3) The first film is placed in a carbonization furnace and carbonized at 800°C for 2 hours; then the first film is transferred to a graphitization furnace, nitrogen is introduced as a protective gas, and graphitized at 2100°C for 20 hours; then the second film is calendered using a calender to obtain a graphene heat dissipation film.

[0202] Comparative Example 8

[0203] This comparative example is basically the same as comparative example 7, except that in step (1), the mass ratio of graphene oxide to defect repair agent glucose is 10:2.

[0204] Comparative Example 9

[0205] This comparative example is basically the same as comparative example 7, except that in step (1), the mass ratio of graphene oxide to the defect repair agent glucose is 10:5.

[0206] Test Case

[0207] 1. Morphological characterization of graphene oxide: The Dimension Icon atomic force microscope (AFM) produced by Bruker, Germany, was used to observe the microscopic morphology and thickness of graphene oxide. The results are shown in Figure 2~Figure 4 .

[0208] Figure 2 is an AFM microscopic morphology image of the first graphene oxide of Example 1, Figure 3 This is an AFM thickness image of the first graphene oxide of Example 1. It can be seen that the lateral size of the first graphene oxide is between 0.35 μm and 3.0 μm, with a typical value of 0.35 μm, and the thickness is between 0.88 nm and 1.98 nm. Figure 4 This is the AFM microscopic morphology image of the second graphene oxide of Example 1. It can be seen that the lateral size of the second graphene oxide is between 50nm and 100nm, and the thickness is 1nm to 2nm.

[0209] 2. Morphological characterization of the second film: The microscopic morphology of the graphene heat dissipation film was observed using a SU-8100 scanning electron microscope (SEM) produced by Hitachi, Japan. The results are shown in Figure 5~Figure 6 .

[0210] Figure 5 This is a SEM image of the front side of the second film obtained in Example 1. Figure 6 This is a SEM image of the cross section of the second film prepared in Example 1. It can be seen that the second film has a high surface flatness, very few structural defects, and a layered structure in the cross section.

[0211] 3. Performance test of graphene heat dissipation film:

[0212] (1) Thermal conductivity test: The density of the sample was calculated by the mass volume method; the specific heat capacity Cp of the sample at room temperature (25°C) was tested by differential scanning calorimetry (DSC), the temperature range was -5°C~55°C, and the heating rate and cooling rate were 20°C / min; the thermal conductivity of the sample at room temperature (25°C) was tested by the laser flash method and the DXF-200 laser thermal conductivity meter produced by TA in the United States; the graphene heat dissipation film was cut into discs with a diameter of 25.4 mm, and then placed in the In-plane mold of the thermal conductivity meter for lateral (in-plane) thermal diffusion coefficient measurement; the product of density, specific heat capacity and thermal diffusion coefficient is the thermal conductivity of the sample. The results are shown in Table 2.

[0213] (2) Temperature reduction effect test: A thermal management simulation tester was used and the constant output power was set to 2W. The temperature T1 of the heat source without graphene heat dissipation film was 85°C, the area of ​​the heat source was 2cm×2cm, and the area of ​​the graphene heat dissipation film of the sample to be tested was 9cm×6cm. One side of the sample was aligned with the corner of the heat source. The temperature T2 of the heat source was tested 15 minutes after the graphene heat dissipation film was applied. The difference between the two heat source temperatures was recorded as the cooling effect (∆T=T1-T2) in °C. The results are shown in Table 2.

[0214] It can be seen from Table 2 that the graphene heat dissipation films prepared in Examples 1 to 9 have a thickness of 80 μm and a density of 1.99 g / cm 3 ~2.14g / cm 3 , the lateral diffusion coefficient is 930 mm 2 / s~989mm 2 / s, thermal conductivity is 1478W / (m·K)~1651W / (m·K), and cooling effect ∆T=34℃~43℃. Compared with the graphene heat dissipation films prepared in comparative examples 1~9, the graphene heat dissipation films prepared in embodiments 1~9 have higher lateral thermal diffusion coefficient, higher thermal conductivity and better cooling effect at the same thickness.

[0215] Table 1. Preparation parameters of graphene heat dissipation film

[0216]

[0217] Table 2. Performance comparison of graphene heat dissipation films

[0218]

[0219] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0220] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of protection of the present application. 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 application, and these all belong to the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a graphene heat dissipation film, characterized in that: The following steps are involved: preparing a mixed slurry containing graphene oxide and a defect repairing agent; Performing film-forming treatment on the mixed slurry to obtain a first film; Carrying out carbonization, graphitization and calendering treatments on the first film to obtain a second film; forming a radiation heat dissipation layer on the second film to obtain a graphene heat dissipation film; Wherein, the graphene oxide includes at least two of a first graphene oxide, a second graphene oxide and a third graphene oxide; The lateral size of the first graphene oxide is greater than the lateral size of the second graphene oxide; The lateral size of the second graphene oxide is greater than the lateral size of the third graphene oxide; The defect repairing agent includes at least one of glucose, citric acid, citrate and vitamin C.

2. The method for preparing a graphene heat dissipation film according to claim 1, characterized in that: The lateral size of the first graphene oxide is 0.1 μm to 3.0 μm; The lateral size of the second graphene oxide is 50nm~100nm; The lateral size of the third graphene oxide is less than 50 nm.

3. The method for preparing the graphene heat dissipation film according to claim 2, characterized in that: The mass ratio of the first graphene oxide, the second graphene oxide and the third graphene oxide is 1:(0.1-1):(0-1).

4. The method for preparing a graphene heat dissipation film according to any one of claims 1 to 3, characterized in that: One or more of the following conditions are met: (1) The thickness of the graphene oxide is 0.3 nm to 4 nm; (2) The ratio of the atomic percentage of carbon element to the atomic percentage of oxygen element in the graphene oxide is 1.6 to 3.

0.

5. The method for preparing the graphene heat dissipation film according to claim 4, characterized in that: The mass ratio of the graphene oxide to the defect repairing agent is 10:(1-5).

6. The method for preparing a graphene heat dissipation film according to any one of claims 1 to 3, characterized in that: The temperature of the carbonization treatment is 600°C to 1000°C, and the time is 2h to 5h; The graphitization treatment is carried out under a protective atmosphere at a temperature of 1500° C. to 2500° C. for a time of 2 h to 30 h.

7. The method for preparing the graphene heat dissipation film according to claim 6, characterized in that: The thickness of the second film is 10 μm to 80 μm, and the density is 1.5 g / cm 3 ~2.2g / cm 3 .

8. The method for preparing the graphene heat dissipation film according to claim 7, characterized in that: Forming a radiation heat dissipation layer on the second film comprises the following steps: The radiation heat dissipation coating is sprayed onto the second film to form the radiation heat dissipation layer.

9. The method for preparing a graphene heat dissipation film according to claim 8, characterized in that: The radiation heat dissipation coating comprises one or more of a polyvinylidene fluoride-hexafluoropropylene solution, a first mixed solution containing an inorganic carbon material, and a second mixed solution containing a nano-oxide.

10. A graphene heat dissipation film, characterized in that: The graphene heat dissipation film is prepared by the method for preparing the graphene heat dissipation film according to any one of claims 1 to 9.

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