Graphene heat dissipation film and preparation method thereof

Abstract

The invention discloses a graphene heat dissipation film and a preparation method thereof, and relates to the technical field of heat dissipation materials.The method comprises the steps that graphene powder and doped particles are mixed according to the mass fraction of 5-20%, deionized water is added to serve as a dispersion medium, 0.5-5% of a stripping auxiliary agent is added, treatment is conducted through high-speed shear dispersion and ultrasonic dispersion, and the graphene heat dissipation film is obtained. Uniform and stable modified graphene slurry is formed; coating the modified graphene slurry on a base material layer by layer according to a sequence from low thermal conductivity to high thermal conductivity, controlling the coating thickness by adopting a scraper or a spin coating process, and performing pre-drying treatment after coating each layer; the coated film is dried at the temperature of 80-200 DEG C, and the interlayer bonding strength is enhanced through chemical curing or thermocuring. Through innovative design of a modified graphene material and optimization of a multi-layer gradient structure, comprehensive improvement of thermal conductivity, mechanical properties and stability of the graphene heat dissipation film is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation materials, and in particular to a graphene heat dissipation film and a preparation method thereof. Background Art

[0002] Graphene has broad application prospects in the field of heat dissipation due to its excellent thermal conductivity and mechanical properties. As a two-dimensional material, graphene has a high thermal conductivity (theoretical value can reach 5300W / m·K), and is one of the materials with the highest thermal conductivity known so far. Therefore, it is widely used in electronic equipment, heat dissipation modules and aerospace fields. However, in practical applications, the preparation of graphene heat dissipation films still faces many challenges:

[0003] Dispersion uniformity problem: Graphene materials tend to agglomerate during the preparation process, resulting in decreased thermal conductivity and affecting the uniformity and stability of the film. In the prior art, the selection of dispersants and stripping processes has an important impact on the uniformity of the slurry, but further optimization is still needed.

[0004] Structural design limitations: Traditional graphene heat dissipation films are usually single-layer structures and cannot effectively meet complex heat dissipation requirements. The single-layer thermal conductivity design cannot meet the step-by-step heat dissipation requirements from low heat source areas to high heat source areas, limiting the application of graphene heat dissipation films in high-performance devices.

[0005] Complexity of preparation process: The preparation of graphene film involves multiple processes such as peeling, coating, curing and calendering. The instability of various process parameters in the existing methods will significantly affect the thermal conductivity and mechanical properties of the heat dissipation film. Therefore, an efficient and stable preparation method is needed to ensure the performance consistency of the heat dissipation film.

[0006] Insufficient room for optimization of material performance: Current graphene heat dissipation films are mostly based on pure graphene, lacking effective doping or composite modification methods, and failing to fully utilize the synergistic effect between graphene and other high thermal conductivity materials (such as metal or ceramic particles).

[0007] In view of the above problems, the present invention proposes a graphene heat dissipation film and a preparation method thereof, which effectively solves the deficiencies in the prior art through optimized preparation of modified graphene slurry, multi-layer gradient structure design and precise control of process parameters. Summary of the invention

[0008] In order to solve the technical problems existing in the above-mentioned prior art, the present invention provides a graphene heat dissipation film and a preparation method thereof.

[0009] To achieve the above object, the present invention provides a method for preparing a graphene heat dissipation film, the method comprising:

[0010] S1: Graphene powder and doped particles are mixed at a mass fraction of 5-20%, deionized water is added as a dispersion medium, 0.5-5% of a stripping aid is added, and high-speed shear dispersion and ultrasonic dispersion are performed to form a uniform and stable modified graphene slurry;

[0011] S2: coating the modified graphene slurry on the substrate layer by layer in the order of low thermal conductivity to high thermal conductivity, using a doctor blade or spin coating process to control the coating thickness, and performing a pre-drying treatment after each layer is coated;

[0012] S3: Drying the coated film at 80-200°C and enhancing the interlayer bonding strength by chemical curing or thermal curing;

[0013] S4: The dried and solidified film is calendered, the pressure is controlled within the range of 5-50 MPa, the thickness and surface smoothness of the film are adjusted, and finally a graphene heat dissipation film with a thickness of 10-200 μm is formed.

[0014] Preferably, the graphene powder in S1 has a particle size of 1-10 μm and an oxygen content of less than 3%; and the particle size range of the doped particles is 50-500 nm.

[0015] Preferably, in S1, after stirring at a speed of 3000-6000 rpm for 30-60 minutes by a high-speed shear disperser, ultrasonic dispersion treatment is performed for 15-30 minutes.

[0016] Preferably, during the S2 gradient coating process, the coating thickness of each layer is controlled at 5-20 μm, and vacuum degassing is performed after coating, and the vacuum degree is controlled at 0.08-0.1 MPa.

[0017] Preferably, the drying and curing process in S3 is carried out in a temperature range of 80-200° C. and the time is controlled to be 1-3 hours.

[0018] Preferably, the graphene heat dissipation film after the calendering treatment in S4 has a thickness of 10-200 μm and a thermal conductivity greater than 1200 W / m·K.

[0019] Preferably, the interface adhesive is at least one of polyimide, epoxy resin or polyethylene terephthalate.

[0020] On the other hand, the present invention provides a graphene heat dissipation film, which is prepared by the above-mentioned preparation method.

[0021] Preferably, the graphene heat dissipation film comprises the following structure:

[0022] A modified graphene layer, wherein the modified graphene layer is formed of a graphene material doped with metal nanoparticles or ceramic particles;

[0023] A multi-layer gradient structure is composed of modified graphene layers with increasing thermal conductivity, and each layer is connected by a high thermal conductivity interface adhesive.

[0024] Preferably, the metal nanoparticles doped in the modified graphene layer are silver, copper or aluminum, and the doping ratio is 5-20% by mass; the ceramic particles are boron nitride, silicon carbide or aluminum oxide, and the doping ratio is 2-15% by mass.

[0025] Compared with the prior art, the present invention provides a graphene heat dissipation film and a preparation method thereof, which have the following beneficial effects:

[0026] (1) The present invention forms a modified graphene layer by doping metal nanoparticles or ceramic particles into a graphene material. The metal nanoparticles and ceramic particles have high thermal conductivity. When they are compounded with graphene, they can effectively enhance the thermal conductivity of the heat dissipation film. In addition, graphene, as a two-dimensional material, has extremely high thermal conductivity, and metal or ceramic particles, as thermal conductive fillers, can provide additional heat transfer paths in the material. By doping the particles, the thermal conductivity of the graphene heat dissipation film is significantly improved, and the thermal conductivity can reach 1200W / m·K or higher.

[0027] (2) The present invention adopts a multi-layer gradient structure design, that is, materials with different thermal conductivity are used on different layers of the heat dissipation film, wherein the low thermal conductivity material is located at the bottom layer, and the high thermal conductivity material is located at the surface layer, forming a layer-by-layer increasing structure from low thermal conductivity to high thermal conductivity. This gradient structure design enables the thermal conductivity to be gradually improved when the heat flow flows from the low heat source area to the high heat source area, thereby reducing heat accumulation and accelerating heat dissipation.

[0028] (3) Through precise control of the process steps such as coating, drying, curing and calendering, the present invention can prepare a uniform and stable graphene heat dissipation film. The gradient coating technology is used in the coating process to ensure that the thickness of each layer of material is consistent, thereby avoiding unstable thermal conductivity caused by uneven coating. The calendering process enhances the mechanical strength of the film by adjusting the pressure and temperature, so that the graphene heat dissipation film after film formation not only has excellent thermal conductivity, but also has good pressure resistance and durability.

[0029] (4) The present invention adopts a technology combining ultrasonic dispersion and high-speed shear dispersion in the preparation process of modified graphene slurry, which effectively improves the dispersion uniformity of graphene and doped particles. By precisely controlling the stripping agent and the dispersion process, the graphene agglomeration phenomenon is avoided, and the thermal conductivity and surface smoothness of the film are improved. In addition, the interface adhesive is used to enhance the bonding strength between different material layers, so that the heat conduction efficiency between the layers is guaranteed, and the phenomenon of interlayer separation or falling off is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0031] Figure 1 Schematic diagram of the process of preparing the graphene heat dissipation film in the embodiment. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0033] This embodiment provides a method for preparing a graphene heat dissipation film, such as Figure 1 As shown, the method includes:

[0034] Step 1: Preparation of modified graphene slurry

[0035] The graphene powder and the doped particles are mixed at a mass fraction of 5-20%, and deionized water is added as a dispersion medium to form a slurry mixture.

[0036] In some embodiments, the metal nanoparticles doped in the modified graphene layer are silver, copper or aluminum, and the doping ratio is 5-20% by mass; the ceramic particles are boron nitride, silicon carbide or aluminum oxide, and the doping ratio is 2-15% by mass; 0.5-5% of a stripping aid is added to the mixture, and the stripping aid is selected from polyvinyl pyrrolidone (PVP), sodium dodecyl sulfate (SDS) or other conventional dispersants; a high-speed shear disperser is used for preliminary dispersion treatment, the speed is 3000-6000rpm, and stirring is continued for 30-60 minutes; the mixed slurry is then transferred to an ultrasonic dispersion equipment for ultrasonic treatment, the power is 300-500W, and the treatment time is 15-30 minutes, so as to further reduce the aggregation of graphene particles and ensure uniform dispersion; the treated slurry is filtered through a 200-mesh sieve to remove the particles that are not fully dispersed, so as to obtain a uniform and stable modified graphene slurry.

[0037] Step 2: Gradient coating

[0038] According to the heat dissipation performance requirements, the modified graphene slurry is coated on the substrate layer by layer in the order of low thermal conductivity to high thermal conductivity.

[0039] In some embodiments, the coating process is as follows:

[0040] The bottom layer is coated with low thermal conductivity slurry, the thickness is controlled at 10-20μm, and the surface is flat;

[0041] The middle layer uses medium thermal conductivity slurry with a thickness of 5-10μm to ensure the bonding strength with the upper and lower layers;

[0042] The surface coating uses high thermal conductivity slurry with a thickness controlled at 5-20μm to ensure the ultimate thermal conductivity of the heat dissipation film;

[0043] The coating process uses a doctor blade or spin coating process, and pre-drying is performed immediately after coating. The drying temperature is 50-80°C and the duration is 10-20 minutes;

[0044] After each layer is coated, vacuum degassing treatment is carried out, and the vacuum degree is controlled at 0.08-0.1MPa to remove bubbles and ensure that the slurry completely penetrates the substrate to form a uniform film layer.

[0045] Step 3: Drying and curing:

[0046] The coated film is placed in a drying oven and dried at a temperature range of 80-200°C for 1-3 hours to ensure that there is no moisture remaining on the surface of the film.

[0047] In some embodiments, while drying, the film layer is chemically cured or thermally cured to enhance the interlayer bonding strength; chemical curing can be performed by adding a curing agent or introducing an inert gas environment during the heat treatment process.

[0048] Step 4: Calendering

[0049] The dried and cured film is calendered to further improve its mechanical strength and surface smoothness.

[0050] In some embodiments, the calendering pressure is controlled in the range of 5-50 MPa, and the thickness of the film is adjusted to 10-200 μm; the temperature during the calendering process can be set to 80-150°C to maintain the flexibility and stability of the film; the film is cooled after calendering to ensure that the surface of the film is smooth and wrinkle-free, and finally a graphene heat dissipation film with excellent thermal conductivity and stability is obtained.

[0051] The following is an introduction to the method for preparing the graphene heat dissipation film of the present invention based on specific embodiments.

[0052] Example 1

[0053] This embodiment discloses a method for preparing a graphene heat dissipation film, and the preparation method comprises the following steps:

[0054] (1) Graphene powder and doped particles were mixed at a mass fraction of 5%, deionized water was added as a dispersion medium, 0.5% of polyvinylpyrrolidone (PVP) was added, and a high-speed shear disperser was used for preliminary dispersion treatment at a speed of 4500 rpm and continuous stirring for 45 minutes; the mixed slurry was then transferred to an ultrasonic dispersion device for ultrasonic treatment at a power of 400 W for 20 minutes; the treated slurry was filtered through a 200-mesh sieve to remove inadequately dispersed particles, thereby obtaining a uniform and stable modified graphene slurry.

[0055] (2) The modified graphene slurry is coated on the substrate layer by layer in the order of low thermal conductivity to high thermal conductivity, that is, the bottom layer is coated with low thermal conductivity slurry with a thickness controlled at 10 μm, and pre-drying is performed immediately after coating, with a drying temperature of 50°C and a duration of 10 minutes; after the layer is coated, vacuum degassing is performed with a vacuum degree controlled at 0.08 MPa.

[0056] (3) The coated film was placed in a drying oven and dried at a temperature of 120° C. for 1 hour.

[0057] (4) The dried and solidified film is rolled, the pressure is controlled within the range of 25 MPa, the thickness and surface smoothness of the film are adjusted, and finally a graphene heat dissipation film with a thickness of 50 μm is formed.

[0058] Example 2

[0059] This embodiment discloses a method for preparing a graphene heat dissipation film, and the preparation method comprises the following steps:

[0060] (1) Graphene powder and doped particles were mixed at a mass fraction of 10%, deionized water was added as a dispersion medium, 0.5% of polyvinylpyrrolidone (PVP) was added, and a high-speed shear disperser was used for preliminary dispersion treatment at a speed of 4500 rpm and continuous stirring for 45 minutes; the mixed slurry was then transferred to an ultrasonic dispersion device for ultrasonic treatment at a power of 400 W for 20 minutes; the treated slurry was filtered through a 200-mesh sieve to remove particles that were not fully dispersed, thereby obtaining a uniform and stable modified graphene slurry.

[0061] (2) The modified graphene slurry is coated on the substrate layer by layer in the order of low thermal conductivity to high thermal conductivity, that is, the bottom layer is coated with low thermal conductivity slurry with a thickness controlled at 10 μm; the surface layer is coated with high thermal conductivity slurry with a thickness controlled at 10 μm, and pre-drying treatment is performed immediately after coating, the drying temperature is 50°C, and the duration is 10 minutes; after layer coating, vacuum degassing treatment is performed, and the vacuum degree is controlled at 0.08 MPa.

[0062] (3) The coated film was placed in a drying oven and dried at a temperature of 120° C. for 1 hour.

[0063] (4) The dried and solidified film is rolled, the pressure is controlled within the range of 25 MPa, the thickness and surface smoothness of the film are adjusted, and finally a graphene heat dissipation film with a thickness of 50 μm is formed.

[0064] Example 3

[0065] This embodiment discloses a method for preparing a graphene heat dissipation film, and the preparation method comprises the following steps:

[0066] (1) Graphene powder and doped particles were mixed at a mass fraction of 20%, deionized water was added as a dispersion medium, 0.5% of polyvinyl pyrrolidone (PVP) was added, and a high-speed shear disperser was used for preliminary dispersion treatment at a speed of 4500 rpm and continuous stirring for 45 minutes; the mixed slurry was then transferred to an ultrasonic dispersion device for ultrasonic treatment at a power of 400 W for 20 minutes; the treated slurry was filtered through a 200-mesh sieve to remove particles that were not fully dispersed, thereby obtaining a uniform and stable modified graphene slurry.

[0067] (2) The modified graphene slurry is coated on the substrate layer by layer in the order of low thermal conductivity to high thermal conductivity, that is, the bottom layer is coated with low thermal conductivity slurry with a thickness controlled at 10 μm; the middle layer is coated with medium thermal conductivity slurry with a thickness controlled at 10 μm; the surface layer is coated with high thermal conductivity slurry with a thickness controlled at 10 μm, and pre-drying treatment is performed immediately after coating, the drying temperature is 50°C, and the duration is 10 minutes; after layer coating, vacuum degassing treatment is performed, and the vacuum degree is controlled at 0.08 MPa.

[0068] (3) The coated film was placed in a drying oven and dried at a temperature of 120° C. for 1 hour.

[0069] (4) The dried and solidified film is rolled, the pressure is controlled within the range of 25 MPa, the thickness and surface smoothness of the film are adjusted, and finally a graphene heat dissipation film with a thickness of 50 μm is formed.

[0070] The structural data of the above embodiment are shown in the following table. It can be seen that with the increase of the number of coating layers and the film thickness, the thermal conductivity of the graphene heat dissipation film gradually increases, reaching a theoretically higher value (such as 1500W / m·K). At the same time, the mechanical strength and thermal conductivity uniformity of the film are also optimized with the increase of the number of coating layers, indicating that the multi-layer gradient structure can effectively improve the overall performance and stability of the film.

[0071]

[0072] In the table:

[0073] Number of coating layers: Graphene films with different numbers of coating layers use different gradient structures, gradually transitioning from low thermal conductivity layers to high thermal conductivity layers to improve the overall thermal conductivity of the film.

[0074] Film thickness: Different film thicknesses affect heat dissipation performance. Appropriate film thickness helps improve thermal conductivity and mechanical strength, but too thick a film may increase weight and affect the practical application of the device.

[0075] Thermal conductivity: Thermal conductivity is the core indicator to measure the performance of heat dissipation film. Higher thermal conductivity indicates that the heat dissipation film has better heat dissipation ability. As the number of coating layers increases, the thermal conductivity gradually increases, indicating that the multi-layer structure effectively enhances the thermal conductivity.

[0076] Tensile strength and elongation at break: reflect the mechanical strength and ductility of the film. Higher tensile strength and moderate elongation at break indicate that the film material has better stability and toughness during the heat dissipation process.

[0077] Surface smoothness: Surface smoothness directly affects the thermal conductivity and practical application effect of the heat dissipation film. A smooth surface can improve heat dissipation efficiency, reduce air resistance, and improve heat dissipation performance.

[0078] Thermal conductivity uniformity: measures the uniform distribution of heat flow within the film. Higher thermal conductivity uniformity indicates that the thermal conductivity of the film is more stable and can maintain better heat dissipation in complex environments.

[0079] In the description of the present invention, the terms "first", "second", "another", and "yet another" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0080] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0081] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing a graphene heat dissipation film, characterized in that: The method comprises: S1: Graphene powder and doped particles are mixed at a mass fraction of 5-20%, deionized water is added as a dispersion medium, 0.5-5% of a stripping aid is added, and high-speed shear dispersion and ultrasonic dispersion are performed to form a uniform and stable modified graphene slurry; S2: coating the modified graphene slurry on the substrate layer by layer in the order of low thermal conductivity to high thermal conductivity, using a doctor blade or spin coating process to control the coating thickness, and performing a pre-drying treatment after each layer is coated; S3: Drying the coated film at 80-200°C and enhancing the interlayer bonding strength by chemical curing or thermal curing; S4: The dried and solidified film is calendered, the pressure is controlled within the range of 5-50 MPa, the thickness and surface smoothness of the film are adjusted, and finally a graphene heat dissipation film with a thickness of 10-200 μm is formed.

2. The method for preparing a graphene heat dissipation film according to claim 1, characterized in that: The particle size of graphene powder in S1 is 1-10 μm, and the oxygen content is less than 3%; the particle size range of doped particles is 50-500 nm.

3. The method for preparing a graphene heat dissipation film according to claim 1, characterized in that: In S1, the mixture is stirred at 3000-6000 rpm for 30-60 minutes by a high-speed shearing disperser, and then ultrasonic dispersion treatment is performed for 15-30 minutes.

4. The method for preparing a graphene heat dissipation film according to claim 1, characterized in that: During the S2 gradient coating process, the coating thickness of each layer is controlled at 5-20 μm, and vacuum degassing is performed after coating, and the vacuum degree is controlled at 0.08-0.1 MPa.

5. The method for preparing a graphene heat dissipation film according to claim 1, characterized in that: The drying and curing process in S3 is carried out in a temperature range of 80-200° C. and the time is controlled to be 1-3 hours.

6. The method for preparing a graphene heat dissipation film according to claim 1, characterized in that: The thickness of the graphene heat dissipation film after the calendering treatment in S4 is 10-200 μm, and its thermal conductivity is greater than 1200 W / m·K.

7. The method for preparing a graphene heat dissipation film according to claim 1, characterized in that: The interface adhesive is at least one of polyimide, epoxy resin or polyethylene terephthalate.

8. 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 7.

9. The graphene heat dissipation film according to claim 8, characterized in that: Includes the following structures: A modified graphene layer, wherein the modified graphene layer is formed of a graphene material doped with metal nanoparticles or ceramic particles; A multi-layer gradient structure is composed of modified graphene layers with increasing thermal conductivity, and each layer is connected by a high thermal conductivity interface adhesive.

10. The graphene heat dissipation film according to claim 9, characterized in that: The metal nanoparticles doped in the modified graphene layer are silver, copper or aluminum, with a doping ratio of 5-20% by mass; the ceramic particles are boron nitride, silicon carbide or aluminum oxide, with a doping ratio of 2-15% by mass.

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