High thermal conductivity / electromagnetic shielding bifunctional film composite material and preparation and application thereof

Abstract

The invention relates to the technical field of new materials, and provides a preparation method of a graphene nanosheet film composite material, which comprises the following steps: mixing a PBAT solution with the mass concentration of 3-5 mg / mL, graphene nanosheets and a metal material under the ultrasonic condition of below 50 DEG C to obtain a suspension, filtering the suspension to obtain a filter cake, and drying the filter cake to obtain the graphene nanosheet film composite material. The filter cake is dried and hot-pressed to obtain the graphene nanosheet film composite material with a layered structure of which the microstructure is arranged in parallel and which can be bent macroscopically; the density of the graphene nanosheet film composite material is 1.2 g / cm < 3 > or below, the graphene nanosheet film composite material has certain flexibility, good thermal conductivity and electrical conductivity and electromagnetic shielding performance, and the solution method device is simple and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of new materials, and particularly relates to a high thermal conductivity / electromagnetic shielding dual-functional thin film composite material, a preparation method thereof, and an application thereof. Background Art

[0002] The rapid development of electronic communication devices has brought challenges in effective heat dissipation and electromagnetic interference shielding. Overheating and harmful electromagnetic interference (EMI) usually hinder the normal operation of devices and shorten their lifespan. Therefore, there is a need for dual-functional materials with high thermal conductivity and excellent electromagnetic shielding performance to quickly balance the uneven heat generated during device operation and output excess heat, while preventing electromagnetic waves from interfering with electronic components and improving device stability. Filled thermal conductive composite materials can not only greatly improve the thermal conductivity of materials, but also improve the mechanical properties, thermal stability, chemical stability, electromagnetic shielding performance, etc. of materials to a certain extent, and have the advantages of multifunctionality. Commonly used high thermal conductivity fillers include carbon materials and metal fillers, etc.

[0003] Among them, carbon materials, such as graphene nanosheets (GNP), multi-layer graphene, and graphene oxide, are ideal materials for producing high-performance nanofilms, which are characterized by excellent electrical conductivity and ultra-high intrinsic thermal conductivity. Therefore, they are considered materials with great development potential. However, GNP has problems common to carbon materials such as aggregation and dispersibility, which greatly limit its application. Most metal fillers have free electrons that can move inside, enabling efficient heat transfer. Therefore, most metal materials themselves have relatively high intrinsic thermal conductivity coefficients and excellent electrical conductivity. Commonly used metal fillers mainly include aluminum, silver, copper, etc. However, due to the huge differences in structure and physical properties between metal fillers and polymers, the mechanical properties and processing properties of composite materials are affected as the amount of metal fillers added increases.

[0004] To solve the defects of the above fillers in preparing dual-functional materials with high thermal conductivity and electromagnetic shielding performance, it is feasible to select a suitable polymer to match it to obtain a composite material that is easy to process. Poly(butylene adipate-co-terephthalate) (PBAT for short) is a copolymer of butylene adipate (PBA) and butylene terephthalate (PBT), and combines the characteristics of PBA and PBT. Due to its good biodegradability, its application scope is gradually expanding. However, there is a lack of research on the above dual-functional materials with PBAT as the main binding material in the prior art. Summary of the Invention

[0005] In the research of the present invention, it is found that when PBAT is used as the main binder and compounded with graphene nanosheets and metal fillers, the material selection and compounding process both have certain effects on the performance of the resulting composite material. Generally, in order to solve the agglomeration problem of inorganic fillers such as graphene nanosheets in polymers, the existing common compounding processes tend to adopt complex compounding processes such as in-situ polymerization and interfacial modification. Based on this, the present invention provides a high thermal conductivity / electromagnetic shielding bifunctional thin film composite material and its preparation and application, realizing a simple process of ultrasonic filtration - hot pressing, and obtaining a thin film material with a density of 1.2 g / cm 3 Hereinafter, the electrical conductivity is above 2400 S / cm, the thermal conductivity is above 70 W / (m K), and the specific shielding effect is 8500 dB cm 2 g -1 or more and does not break under 180° bending.

[0006] In a first aspect, the present invention provides a method for preparing a graphene nanosheet thin film composite material, comprising: Mixing a PBAT solution with a mass concentration of 3 - 5 mg / mL, graphene nanosheets and a metal material under ultrasonic conditions below 50°C to obtain a suspension, filtering the suspension to obtain a filter cake, and drying and hot pressing the filter cake to obtain a graphene nanosheet thin film composite material with a microscopically parallel arranged layered structure and macroscopically bendable; The density of the graphene nanosheet thin film composite material is 1.2 g / cm 3 or less; The mass ratio of the graphene nanosheets to the metal material is 4 - 6:1; the mass ratio of the graphene nanosheets to PBAT in the PBAT solution is 1:9 - 11.

[0007] In the present invention, when preparing the thin film material with the above-mentioned layered structure, the methods of ultrasonic treatment and suction filtration are adopted. At the beginning of ultrasonic treatment, graphene nanosheets are grafted together through PBAT. As the ultrasonic process proceeds, continuous graphene layers are formed, and Ag is adsorbed on the surface of the graphene layer due to the high viscosity of PBAT. After ultrasonic treatment is completed, suction filtration is carried out, and the graphene layers are oriented in the direction of gravity to form a parallel arranged layered structure. The size of the interlayer pores is related to the polymer content. Further, the method of hot pressing is adopted to form a stable, continuous and parallel arranged multi-layer structure that can be macroscopically bent. In the method of the present invention, when the concentration of PBAT is greater than 5 mg / mL, the viscosity of the solution system increases, the molecular chains of PBAT are severely entangled, and the skeletons are bonded to each other, resulting in the agglomeration of graphene nanosheets. It has been experimentally verified that a regular and continuous layered structure can be formed by using a PBAT solution with a mass concentration of 3-5 mg / mL and controlling the contents of graphene nanosheets, metal materials and PBAT within the above ranges. Temperature control during ultrasonic treatment is to ensure uniform dispersion, and drying is to remove the residual solution in the film after filtration. Without drying, hot pressing cannot be carried out.

[0008] According to the preparation method of the graphene nanosheet thin film composite material provided by the present invention, the diameter of the graphene nanosheets is 5-10 μm, and the thickness is 3-10 nm.

[0009] According to the preparation method of the graphene nanosheet thin film composite material provided by the present invention, the metal material is one or a combination of two or more of nano silver powder, nano silver wire and nano silver sheet, preferably nano silver powder; preferably, the particle size of the nano silver powder is 10-30 nm; wherein, the preferred nano Ag in the present invention is uniformly adsorbed on the skeleton of the GNP thin film composite material, solving the problem of reduced electrothermal performance caused by defects in graphene nanosheets, protecting the thermal and conductive network, and effectively improving the electrothermal performance of the thin film material.

[0010] According to the preparation method of the graphene nanosheet thin film composite material provided by the present invention, the solvent of the PBAT solution is selected from one or a combination of two or more of dioxane, acetone, tetrahydrofuran, dimethylformamide and dichloroethane, preferably dimethylformamide.

[0011] PBAT has good solubility. Considering the dispersion performance of graphene nanosheets and metal materials in the present invention, the above solvents are preferred in the present invention.

[0012] According to the preparation method of the graphene nanosheet thin film composite material provided by the present invention, the number average molecular weight of PBAT is about 30-40 kDa.

[0013] According to the preparation method of the graphene nanosheet thin film composite material provided by the present invention, the preparation process of the suspension includes: Premix the PBAT solution, graphene nanosheets, and metal material to obtain a premixed solution; Subject the premixed solution to intermittent ultrasound and maintain an ice bath throughout to obtain the suspension; in the intermittent ultrasound, the interval time between every two adjacent ultrasounds is 3 - 8 s, and the time for each ultrasound is 3 - 8 s; Preferably, the ultrasonic power is 100 - 200 W; the total time of the intermittent ultrasound is 30 - 60 min.

[0014] According to the preparation method of the graphene nanosheet thin film composite material provided by the present invention, perform suction filtration on the suspension; preferably, the pore size of the filter paper used for suction filtration is 1 - 1.5 μm. If the particle size of the filter paper is too small, suction filtration will be very difficult, resulting in difficulty in forming a film.

[0015] According to the preparation method of the graphene nanosheet thin film composite material provided by the present invention, after drying the filter cake to constant weight, press it at 120 - 180 °C and above 10 MPa for more than 2 min to obtain the graphene nanosheet thin film composite material.

[0016] In the preparation method of the present invention, the thickness of the thin film can be controlled by adjusting the temperature and pressure of hot pressing.

[0017] More specifically, the preparation method of the graphene nanosheet thin film composite material includes the following steps: Prepare a uniform polymer solution by heating and stirring PBAT and a solvent; wherein, the stirring speed is 500 - 1500 rpm, and the heating temperature is 100 - 150 °C.

[0018] Add graphene nanosheets and metal material to the polymer solution, and obtain a uniform suspension through ultrasonic dispersion; Perform suction filtration on the suspension to obtain a filter cake; Vacuum dry the filter cake, and then perform hot pressing to prepare a graphene nanosheet thin film composite material. Among them, the temperature of vacuum drying is 60 - 150 °C.

[0019] Second, the present invention also provides a graphene nanosheet thin film composite material prepared by the preparation method of the graphene nanosheet thin film composite material as described above. The density of the graphene nanosheet thin film composite material is 1.2 g / cm 3 Below, the electrical conductivity is above 2400 S / m, the thermal conductivity is above 70 W / (m·K), the specific shielding effect is 8500 dB·cm 2 g -1 Above, it does not break during 180° bending.

[0020] Preferably, by mass percentage, the content of GNP in the graphene nanosheet thin film composite material is 60-80%, the content of the metal material is 10-25%, and the balance is PBAT; Preferably, the microstructure of the graphene nanosheet thin film composite material is a layered structure arranged in parallel; the graphene nanosheet thin film composite material does not break when folded 180°.

[0021] Preferably, Ag particles are distributed on the surface of the GNP.

[0022] The thickness of the graphene nanosheet thin film composite material in the present invention is 40-100 μm.

[0023] In a third aspect, the present invention also provides an application of the graphene nanosheet thin film composite material in a battery or a chip radiator. The graphene nanosheet thin film composite material is used for dissipating heat and shielding electromagnetic interference of the battery or the chip radiator.

[0024] A preparation method of a graphene nanosheet thin film composite material provided by the present invention uses PBAT as a polymer binder to form a continuous and stable layered framework of graphene nanosheets, and then uniformly distributes the metal material on the layered graphene framework under the action of ultrasonic waves, and forms a good thermal conduction and electrical conduction network. The prepared thin film composite material with a layered structure has certain flexibility, good thermal conductivity and electrical conductivity, and electromagnetic shielding performance. Moreover, the solution method of the present invention has a simple device and is environmentally friendly.

[0025] Furthermore, the thin film material synthesized by the present invention is light, ultra-thin, has excellent performance, and is widely used. Compared with the pure GNP thin film, its flexibility is significantly improved, while maintaining excellent electromagnetic shielding performance, and the thermal conduction and electrical conduction performance of the material is further improved by adding a highly thermally conductive metal material. Description of the Drawings

[0026] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0027] Figure 1 It is a bending recovery diagram of the thin film materials prepared in Example 1 and Comparative Example 8 provided by the present invention.

[0028] Figure 2It is a scanning electron microscope picture of the cross-section of the PBAT / GNP / Ag thin film composite prepared in Example 1 and Comparative Example 2 provided by the present invention. Among them, Example 1 corresponds to a and b, and Comparative Example 2 corresponds to c.

[0029] Figure 3 It is a TGA graph of the PBAT / GNP / Ag thin film composite prepared in Example 1 provided by the present invention.

[0030] Figure 4 It is an XRD graph of the PBAT / GNP / Ag thin film composite prepared in Example 1 provided by the present invention.

[0031] Figure 5 They are the thermal conductivity and electrical conductivity of the PBAT / GNP / Ag thin film composite prepared in Example 1 provided by the present invention.

[0032] Figure 6 They are the thermal conductivity and electrical conductivity of the PBAT / GNP thin film composite of Comparative Example 1 provided by the present invention.

[0033] Figure 7 It is an electromagnetic shielding performance graph of the PBAT / GNP / Ag thin film composite prepared in Example 1 provided by the present invention. Detailed Embodiments

[0034] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0035] The following will be combined with Figures 1 to 7 Describe a high thermal conductivity / electromagnetic shielding dual-functional thin film composite of the present invention, its preparation method and application.

[0036] For those not specifying specific technologies or conditions in the examples, they shall be carried out according to the technologies or conditions described in the literature in the field or according to the product specifications. For those reagents or instruments not indicating the manufacturer, they are all conventional products that can be obtained through regular channels.

[0037] Specifically, the graphene nanosheets (GNP) used in the examples: sheet diameter: 5 - 10 μm, thickness 3 - 10 nm, produced by Hebei Yancheng Biotechnology Co., Ltd.; polybutylene adipate terephthalate (PBAT): model C1200, produced by BASF Co., Ltd.; N,N-dimethylformamide (DMF) solution, produced by Beijing Innochem Technology Co., Ltd.; nano-Ag, 3A Chemical Company, product number A65264, particle size 20 nm, purity 99.99%.

[0038] Example 1 A preparation method of a lightweight, ultra-thin, highly thermally conductive / electromagnetic shielding dual-functional PBAT / GNP / Ag thin film composite material, the specific preparation steps are as follows: (1) Preparation of the solution: Add PBAT particles to the DMF solution, stir at 130 °C for 1 h, stirring rate 800 rpm, to fully dissolve the PBAT particles, obtain a PBAT solution with a concentration of 3.3 mg / ml, add GNP and nano-Ag to the PBAT solution and continue to stir for 1 h to obtain a first suspension; wherein, the mass ratio of GNP to PBAT particles is 1:10, and the mass ratio of GNP to nano-Ag is 5:1.

[0039] (2) Ultrasonic treatment: Put the suspension obtained in step (1) into a cell disruptor for ultrasonic treatment and keep it ice-bathed throughout. Among them, the ultrasonic power is 150 W, and the ultrasonic time is 40 min in the pulse mode (5 seconds on and 5 seconds off) to make the nano-Ag evenly distributed on the surface of the GNP skeleton, obtaining a second suspension.

[0040] (3) Filtration and hot pressing: Filter the second suspension obtained in step (2) by suction filtration. During the suction filtration process, a PA membrane with a diameter of 47 mm and a pore size of 1.2 μm is selected for the filter paper. After sufficient filtration, take out the PA membrane containing the filter cake and place it in an oven at 70 °C for 2 h to remove most of the solvent, and then dry it at 120 °C for 1 h to completely remove the solvent, so that the filter cake on the PA membrane is fully cured. Finally, use a hot press to press the filter cake on the PA membrane at 140 °C and 10 MPa for 5 min to obtain the PBAT / GNP / Ag thin film composite material.

[0041] Example 2 A preparation method of a lightweight, ultra-thin, highly thermally conductive / electromagnetic shielding dual-functional PBAT / GNP / Ag thin film composite material, the specific preparation steps are basically the same as those in Example 1, the only difference is that: in step (1), the nano-Ag is replaced with an equal mass of one-dimensional nano-Ag wires (average diameter 40 nm) to obtain the PBAT / GNP / Ag thin film composite material.

[0042] Example 3 A preparation method of a lightweight, ultrathin, highly thermally conductive / electromagnetic shielding dual-functional PBAT / GNP / Ag thin film composite material. The specific preparation steps are basically the same as those in Example 1, except that in step (1), an equal mass of nano-Ag is replaced with two-dimensional nano-Ag flakes (flake diameter 4-8 μm) to obtain the PBAT / GNP / Ag thin film composite material.

[0043] Comparative Example 1 This comparative example is basically the same as Example 1, except that in step (1), no nano-Ag particles are added, and a PBAT / GNP thin film composite material is prepared.

[0044] Comparative Examples 2-4 This comparative example is basically the same as Example 1, except that in step (1), the amount of PBAT added is specifically: Comparative Example 2: The mass ratio of GNP to PBAT particles is 1:1; Comparative Example 3: The mass ratio of GNP to PBAT particles is 1:5; Comparative Example 4: The mass ratio of GNP to PBAT particles is 1:15.

[0045] Comparative Examples 5-7 This comparative example is basically the same as Example 1, except that in step (1), the amount of Ag added is specifically: Comparative Example 5: The mass ratio of GNP to nano-Ag is 10:1; Comparative Example 6: The mass ratio of GNP to nano-Ag is 5:2; Comparative Example 7: The mass ratio of GNP to nano-Ag is 5:5.

[0046] Comparative Example 8 A GNP thin film is prepared by adding 50 mg of GNP to 150 mL of DMF solution to obtain a GNP suspension, and the GNP suspension is processed according to steps (2) and (3) in Example 1 to obtain the GNP thin film.

[0047] Comparative Example 9 A preparation method of a lightweight, ultrathin, highly thermally conductive / electromagnetic shielding dual-functional PBAT / GNP / Ag thin film composite material is as follows: (1) Preparation of the solution: Add PBAT particles to DMF solution, stir at 130 °C for 1 h to fully dissolve the PBAT particles, obtain a PBAT solution with a concentration of 3.3 mg / ml, add GNP to the PBAT solution and continue stirring for 1 h to obtain a first PBAT / GNP suspension. Among them, the mass ratio of GNP to PBAT particles is 1:10.

[0048] Add PBAT particles to the DMF solution and stir at 130 °C for 1 h to fully dissolve the PBAT particles, obtaining a PBAT solution with a concentration of 3.3 mg / ml. Add Ag (particle size 1 μm) to the PBAT solution and continue stirring for 1 h to obtain the first PBAT / Ag suspension. Among them, the mass ratio of GNP to nano-Ag is 5:1.

[0049] (2)Ultrasonic treatment: Put the PBAT / GNP suspension and PBAT / Ag suspension obtained in step (1) into a cell disruptor for ultrasonic treatment and keep it ice-bathed throughout the process. Among them, the ultrasonic power is 150 W, and the ultrasonic time is 40 min in pulse mode (5 s on and 5 s off) to obtain the second PBAT / GNP suspension and the second PBAT / Ag suspension respectively.

[0050] (3)Filtration and hot pressing: Alternately filter the first PBAT / Ag suspension and the second PBAT / Ag suspension obtained in step (2). The volume of the suspension during each filtration is 10 mL. During the filtration process, use a PA membrane with a diameter of 47 mm and a pore size of 1.2 μm as the filter paper. After sufficient filtration, take out the PA membrane containing the filter cake and heat it in an oven at 70 °C for 2 h to remove most of the solvent, and then dry it at 120 °C for 1 h to completely remove the solvent, so that the filter cake on the PA membrane is fully cured. Finally, use a hot press to press the filter cake on the PA membrane at 140 °C and 10 MPa for 5 minutes to obtain the PBAT / GNP / Ag thin film composite material.

[0051] Test examples (1)Flexibility test of thin film: Conduct a 180° bending and recovery experiment on the GNP thin film prepared in Comparative Example 8 and the PBAT / GNP / Ag thin film composite material prepared in Example 1. Figure 1 a is the GNP thin film prepared in Comparative Example 8, Figure 1 b is the PBAT / GNP / Ag thin film prepared in Example 1. It can be clearly seen from the figure that the GNP thin film will break directly after bending, while the PBAT / GNP / Ag thin film composite material will have slight creases and can basically return to its original state.

[0052] (2)Observation of microscopic morphology: Freeze the PBAT / GNP / Ag thin film composite material prepared in Example 1 in liquid nitrogen for 1 h and then quickly break it along the transverse direction. After sputtering gold on the cross-section, use a scanning electron microscope (SEM, Helios G4CX, Thermo Scientific) to observe the microscopic morphology of the fractured cross-section. Figure 2 a is the scanning electron microscope image of the cross-section along the transverse direction, Figure 2 b is the enlarged view, Figure 2 c is the thin film obtained in Comparative Example 2. From Figure 2It can be seen that the material prepared in Example 1 exhibits a layered structure with parallel arrangement. Figure 2 b Ag particles distributed on the surface of GNP can be seen. Figure 2 c It can be seen that agglomeration is likely to occur on the surface of the film when the PBAT concentration is high.

[0053] (3) Component testing: Thermogravimetric analysis. Thermogravimetric analysis (TGA) was carried out using a synchronous thermal analyzer (NETZSCH TA449F3). Samples weighing 10 - 15 mg were heated from 35 °C to 800 °C at an oxygen flow rate of 80 mL / min. At least five TGA measurements were performed on each sample to obtain the average and representative values of the experimental deviations of the PBAT content, GNP content, and Ag content. XRD analysis. The composition of the filler was studied using a CT tomographic X-ray diffraction system (PANalytical Empyrean, Netherlands) at 15 - 55°, with a scanning speed of 5° / min.

[0054] From Figure 3 It can be seen that in the PBAT / GNP / Ag thin film composite prepared in Example 1, a characteristic peak of graphene exists at 26°, and a characteristic peak of Ag exists near 38°. It can be concluded that Ag can adhere to the GNP layer through PBAT. Analysis Figure 4 , it can be concluded that in the PBAT / GNP / Ag thin film composite, the PBAT content is approximately 9.4%, the GNP content is approximately 77.3%, and the Ag content is approximately 13.3%.

[0055] (4) Electrothermal performance testing: In order to investigate the conductivity of the PBAT / GNP / Ag thin film composite prepared in the present invention. The resistance (R) of the sample was measured using a digital multimeter (DMM4050, Tektronix, Inc., USA). Before the test, the PBAT / GNP / Ag thin film composite obtained in Example 1 was cut into rectangular specimens of 1 cm × 2 cm, and a layer of conductive silver paste was evenly coated on both ends of the sample to avoid contact resistance between the electrodes and the sample.

[0056] Thermal conductivity: First, the thermal diffusivity of the PBAT / GNP / Ag thin film composite was measured using a laser thermal conductivity meter (NETZSCH LFA467). Before the test, the PBAT / GNP / Ag thin film composite was cut into circular wafers with a diameter of 25.4 mm, and then calculated through the formula: thermal conductivity = thermal diffusivity × density × specific heat capacity.

[0057] From Figures 5 to 6It can be seen that under the same conditions, the electrothermal performance of the PBAT / GNP / Ag film (the material obtained in Example 1) is significantly improved compared to the PBAT / GNP film (the material obtained in Comparative Example 1). At room temperature, the conductivity of the PBAT / GNP / Ag film composite is 3696 S / m, and the thermal conductivity is 81.64 W / (m K).

[0058] (5)Electromagnetic shielding performance test: The EMI shielding performance of the samples in the k-band (18 - 26.5 GHz) was tested using a vector network analyzer (MS46322B, Anritsu). The sample size was 10.671×4.318 mm. From Figure 7 It can be seen that the PBAT / GNP / Ag film composite prepared in Example 1 has high electromagnetic shielding performance, reaching 44.71 dB. To accurately evaluate the true EMI shielding performance of the composite film, the specific shielding efficiency (SSE / t) was calculated by dividing SE by the product of density (ρ) and thickness (t). It can be calculated that the specific shielding effect of the PBAT / GNP / Ag film composite is 8715 dB cm 2 g -1 , where the thickness of the PBAT / GNP / Ag film composite prepared in Example 1 is 45 μm, and the density is about 1.08 g / cm 3 3

[0059] Using the above method, the test results of the composites obtained in Examples 2 - 3 are shown in Table 1 below: Table 1

[0060] Using the above method, the test results of the composites obtained in the comparative examples are shown in Table 2 below: Table 2

[0061] As can be seen from Table 1 above: The conductivity of the composite material in the present invention is 2.16 times higher than that of the PBAT / GNP film composite prepared in Comparative Example 1, and the thermal conductivity is 1.72 times higher. Compared with Comparative Examples 2 - 4 with different PBAT contents, the composite material in the present invention has the best comprehensive performance. Compared with Comparative Examples 5 - 7 with different Ag contents, the composite material in the present invention has the best comprehensive performance.

[0062] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a graphene nanosheet film composite material, characterized in that: include: A PBAT solution with a mass concentration of 3-5 mg / mL, a graphene nanosheet and a metal material are mixed under ultrasonic conditions below 50° C. to obtain a suspension, the suspension is filtered to obtain a filter cake, and the filter cake is dried and hot-pressed to obtain a graphene nanosheet film composite material having a microscopic structure of parallel-arranged layered structures and being macroscopically bendable; The density of the graphene nanosheet film composite material is 1.2 g / cm 3 the following; The mass ratio of the graphene nanosheets to the metal material is 4-6:1; the mass ratio of the graphene nanosheets to the PBAT in the PBAT solution is 1:9-11.

2. The method for preparing the graphene nanosheet film composite material according to claim 1, characterized in that: The graphene nanosheet has a sheet diameter of 5-10 μm and a thickness of 3-10 nm.

3. The method for preparing the graphene nanosheet film composite material according to claim 1 or 2, characterized in that: The metal material is one or a combination of two or more of nano silver powder, nano silver wire and nano silver flake, preferably nano silver powder; preferably, the particle size of the nano silver powder is 10-30 nm.

4. The method for preparing the graphene nanosheet film composite material according to any one of claims 1 to 3, characterized in that: The solvent of the PBAT solution is selected from one or a combination of two or more of dioxane, acetone, tetrahydrofuran, dimethylformamide and dichloroethane, preferably dimethylformamide.

5. The method for preparing the graphene nanosheet film composite material according to any one of claims 1 to 4, characterized in that: The number average molecular weight of the PBAT is about 30-40 kDa.

6. The method for preparing the graphene nanosheet film composite material according to any one of claims 1 to 5, characterized in that: The preparation process of the suspension comprises: Premixing the PBAT solution, graphene nanosheets and metal material to obtain a premixed solution; The premixed liquid is subjected to intermittent ultrasonication and kept in an ice bath throughout the process to obtain the suspension; the interval between each two adjacent ultrasonications in the intermittent ultrasonication is 3 to 8 seconds, and the duration of each ultrasonication is 3 to 8 seconds; Preferably, the ultrasonic power is 100-200 W; and the total time of the intermittent ultrasound is 30-60 min.

7. The method for preparing the graphene nanosheet film composite material according to any one of claims 1 to 6, characterized in that: The suspension is filtered; preferably, the pore size of the filter paper used for the filtration is 1-1.5 μm.

8. The method for preparing the graphene nanosheet film composite material according to any one of claims 1 to 7, characterized in that: The filter cake is dried to a constant weight and then pressed at 120-180° C. and above 10 MPa for more than 2 minutes to obtain the graphene nanosheet film composite material.

9. The graphene nanosheet film composite material obtained by the method for preparing the graphene nanosheet film composite material according to any one of claims 1 to 8, characterized in that: The electrical conductivity is above 2400S / m, the thermal conductivity is above 70W / (m K), and the specific shielding effect is 8500dB cm 2 g -1 Above, 180° bending without breaking.

10. An application of the graphene nanosheet film composite material according to claim 9 in a battery or a chip radiator, characterized in that: The graphene nanosheet film composite material is used for dissipating heat and shielding electromagnetic interference of the battery or chip radiator.

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