Electromagnetic shielding heat dissipation film and preparation method and application thereof

Abstract

The invention discloses an electromagnetic shielding heat dissipation film and a preparation method and application thereof, and relates to the technical field of heat dissipation films, and the electromagnetic shielding heat dissipation film sequentially comprises a matrix layer, a three-dimensional heat conduction network layer, a gradient electromagnetic shielding layer and a function enhancement layer from top to bottom; the function enhancement layer is prepared from the following raw materials in parts by weight: 4 to 6 parts of MXene nanosheets, 3 to 5 parts of boron nitride nanotubes, 100 parts of epoxy resin and 5 to 8 parts of 3, 3 '-diamino-4, 4'-difluorodiphenyl sulfone. The heat dissipation film has efficient electromagnetic wave shielding conduction performance, good heat dissipation performance and good mechanical and stability, and the preparation process is simple and easy to implement.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation films, and in particular to an electromagnetic shielding heat dissipation film and a preparation method and application thereof. Background Art

[0002] In the field of modern electronics, electronic devices are rapidly developing towards miniaturization, high integration, and high performance. This trend has led to an increasingly compact layout of electronic components within these devices. During operation, these components not only generate significant heat but also radiate high-intensity electromagnetic waves, significantly impacting the surrounding environment. Therefore, the development of electromagnetic shielding and heat dissipation film materials with excellent overall performance and stability is particularly important.

[0003] Traditional electromagnetic shielding and heat dissipation materials often struggle to simultaneously meet the requirements for high electromagnetic shielding effectiveness and efficient heat dissipation. Existing electromagnetic shielding and heat dissipation materials often employ a simple stacking of an absorbing layer and a thermally conductive layer, resulting in functional conflicts: the high magnetic loss of the absorbing layer (such as ferrite) reduces the thermal conductivity of the thermally conductive layer (such as graphene); conversely, the high electrical conductivity of the thermally conductive layer weakens the absorbing layer's electromagnetic wave absorption capacity. Furthermore, commercially available electromagnetic shielding and heat dissipation materials often suffer from technical deficiencies such as insufficient stability, high energy consumption, complex manufacturing processes, and environmental concerns.

[0004] To address these issues, Chinese invention patent CN110591579B discloses a method for preparing an electromagnetic shielding and heat dissipation film. The method comprises the following steps: obtaining a mixed aqueous dispersion of carbon nanotubes and graphene, wherein the carbon nanotubes are 100 to 500 microns in length and 6 to 10 nanometers in diameter; obtaining a substrate layer, depositing the mixed aqueous dispersion onto the substrate layer, treating the substrate layer under a protective gas atmosphere at 2800°C to 3000°C for 8 to 12 hours, and pressing the substrate layer to form a self-supporting functional layer; and obtaining a thermally conductive adhesive, depositing the adhesive onto the self-supporting functional layer to form a thermally conductive adhesive layer, thereby obtaining an electromagnetic shielding and heat dissipation film. The electromagnetic shielding and heat dissipation film prepared by this method exhibits high electromagnetic wave shielding and conductivity, high electrical conductivity, and excellent heat dissipation performance. The preparation process is simple and easy to operate, making it suitable for industrial production and application. However, its heat dissipation, mechanical properties, and stability still require further improvement.

[0005] It can be seen that the development of an electromagnetic shielding heat dissipation film that has efficient electromagnetic wave shielding conductivity, good heat dissipation performance, good mechanical and stability, and a simple and easy preparation process, as well as its preparation method and application, meets market demand, has broad market value and application prospects, and is of great significance to promoting the development of the field of electromagnetic shielding heat dissipation materials. Summary of the Invention

[0006] The main purpose of the present invention is to provide an electromagnetic shielding and heat dissipation film, which has efficient electromagnetic wave shielding and conduction performance, good heat dissipation performance, good mechanical and stability, and a simple and easy preparation process, as well as a preparation method and application thereof.

[0007] To achieve the above objectives, the present invention provides an electromagnetic shielding and heat dissipation film, which includes, from top to bottom, a base layer, a three-dimensional thermal conductive network layer, a gradient electromagnetic shielding layer, and a function enhancement layer; the function enhancement layer is made of the following raw materials in parts by weight: 4-6 parts of MXene nanosheets, 3-5 parts of boron nitride nanotubes, 100 parts of epoxy resin, and 5-8 parts of 3,3'-diamino-4,4'-difluorodiphenyl sulfone.

[0008] Preferably, the MXene nanosheets are titanium carbide MXene multilayer nanosheets with a thickness of 100-200 nm and a sheet diameter of 2-10 μm.

[0009] Preferably, the boron nitride nanotubes have a length of 10-20 μm and an average diameter of 50 nm.

[0010] Preferably, the epoxy resin is epoxy resin E-51.

[0011] Preferably, the base layer is made of a polyimide film with a thickness of 50-100 μm.

[0012] Preferably, the thickness of the function enhancement layer is 25-35 μm.

[0013] Preferably, the thickness of the gradient electromagnetic shielding layer is 6-9 μm.

[0014] Preferably, the thickness of the three-dimensional heat conductive network layer is 600-900 μm.

[0015] Another object of the present invention is to provide a method for preparing the electromagnetic shielding and heat dissipation film, comprising the following steps: Step S1, in situ growth of a three-dimensional GNP-CNT thermal conductive network: graphene nanosheets are dispersed in ethanol, filtered to form a GNP film with a thickness of 2-5 μm, and then dried and placed in a CVD reactor; iron nanoparticles are sputtered on the surface of the graphene nanosheets as a catalyst; a mixture of acetylene and argon is introduced and reacted at 680-720°C for 1.8-2.2 hours to in situ grow a CNT array; the sample is placed in an argon atmosphere at 2880-2910°C and hot pressed for 7-9 hours to form covalent bonds between the GNPs and the CNTs to form a three-dimensional thermal conductive network layer; Step S2, gradient electromagnetic shielding layer deposition: using magnetron sputtering to deposit an Ag layer on the surface of the three-dimensional thermal conductive network layer; adjusting the target material ratio to deposit an Ag-Ni alloy layer; replacing the Ni target to deposit a Ni layer to form a gradient structure; Step S3, coating the function-enhancing layer: dispersing MXene nanosheets in N-methylpyrrolidone, adding boron nitride nanotubes, mixing, adding epoxy resin and 3,3'-diamino-4,4'-difluorodiphenyl sulfone, and stirring evenly; coating the mixture on the surface of the gradient shielding layer, and curing to obtain the function-enhancing layer; Step S4, molding: using hot-melt polyurethane adhesive to adhere the above structure to the polyimide film, hot pressing at 150° C. and 0.5 MPa for 28-32 minutes to form an electromagnetic shielding and heat dissipation film.

[0016] Preferably, the graphene nanosheets in step S1 have a diameter of 5-10 μm and a thickness of 3-10 nm.

[0017] Preferably, the amount ratio of the graphene nanosheets to ethanol in step S1 is 1 mg:1 mL.

[0018] Preferably, the particle size of the iron nanoparticles in step S1 is 5-10 nm; the sputtering power is 50 W, and the sputtering time is 10 minutes; the mixed gas is a mixture of acetylene and argon in a volume ratio of 1:10; the CNTs array is perpendicular to the GNP surface, has a diameter of 10-15 nm, and a length of 500-800 μm.

[0019] Preferably, in step S2 , the power for depositing the Ag layer is 200 W, the pressure is 0.4 Pa, and the time is 30 min; the thickness of the Ag layer is 2-3 μm.

[0020] Preferably, the power for depositing the Ag-Ni alloy layer in step S2 is 250 W, the pressure is 0.5 Pa, and the time is 40 min; the mass ratio of Ag to Ni in the target is 8:2; and the thickness of the Ag-Ni alloy layer is 3-4 μm.

[0021] Preferably, in step S2 , the power for depositing the Ni layer is 150 W, the pressure is 0.3 Pa, the time is 20 min, and the thickness of the Ni layer is 1-2 μm.

[0022] Preferably, the amount ratio of the MXene nanosheets to N-methylpyrrolidone in step S3 is 0.5 mg:1 mL.

[0023] Preferably, the curing conditions in step S3 are: first curing at 120° C. for 2 h, and then curing at 180° C. for 3 h.

[0024] Preferably, the hot melt polyurethane adhesive in step S4 is TYFORCE FH-3000.

[0025] Another object of the present invention is to provide an application of the electromagnetic shielding and heat dissipation film in the field of electronic equipment.

[0026] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The preparation method of the electromagnetic shielding and heat dissipation film disclosed in the present invention has a simple preparation process, convenient operation and control, low dependence on equipment, high preparation efficiency and finished product qualification rate, is suitable for continuous large-scale production, and has high promotion and application value.

[0027] (2) The electromagnetic shielding and heat dissipation film disclosed in the present invention comprises, from top to bottom, a base layer, a three-dimensional heat-conducting network layer, a gradient electromagnetic shielding layer, and a function-enhancing layer; the function-enhancing layer is made of the following raw materials in parts by weight: 4-6 parts of MXene nanosheets, 3-5 parts of boron nitride nanotubes, 100 parts of epoxy resin, and 5-8 parts of 3,3'-diamino-4,4'-difluorodiphenyl sulfone. Through the mutual coordination and joint action of the various layers of materials and raw materials, the electromagnetic shielding and heat dissipation film has high-efficiency electromagnetic wave shielding and conduction performance, good heat dissipation performance, good mechanical and stability, and a simple and easy preparation process.

[0028] (3) The electromagnetic shielding heat dissipation film disclosed in the present invention grows a three-dimensional thermal conductive network of "GNP-CNTs" in situ. By precisely controlling the temperature (680-720℃), reaction time (1.8-2.2 hours) and hot pressing conditions (2880-2910℃ hot pressing in an argon atmosphere for 7-9 hours), CNTs are vertically grown on the surface of GNPs and form covalent bonds. Compared with the traditional two-dimensional planar heat dissipation structure, this three-dimensional structure constructs a more efficient heat conduction path. The vertically arranged CNTs act like "heat pipes" and can quickly conduct heat in the axial direction, while the GNP layer provides good heat conduction capacity in the lateral direction. The synergistic effect of the two greatly reduces the overall thermal resistance and significantly improves the thermal conductivity. Compared with the heat dissipation material of the prior art that simply mixes carbon nanotubes and graphene, the thermal conductivity of the three-dimensional thermal conductive network layer prepared by this method is significantly improved, effectively solving the problem of performance degradation of electronic equipment due to heat accumulation.

[0029] (4) The electromagnetic shielding and heat dissipation film disclosed in the present invention forms an electromagnetic shielding layer with a gradient structure by sequentially depositing an Ag layer, an Ag-Ni alloy layer with an adjusted ratio, and a Ni layer through magnetron sputtering. The combination and gradient distribution of different metal layers play a unique role in electromagnetic waves of different frequency bands. The Ag layer has good conductivity and efficiently reflects electromagnetic waves in the low frequency band; the Ag-Ni alloy layer enhances the absorption and reflection of electromagnetic waves in the medium and high frequency bands by virtue of the surface plasma resonance effect; and the Ni layer further optimizes the overall performance of the shielding layer, making up for the shortcomings of the other two layers in certain frequency bands. This gradient structure enables the electromagnetic shielding and heat dissipation film to maintain excellent shielding effectiveness in a wide frequency range (30MHz-18GHz). Compared with a single metal shielding layer or a disordered composite shielding layer, the shielding effectiveness is significantly improved, effectively preventing electronic equipment from electromagnetic interference and internal electromagnetic leakage.

[0030] (5) The electromagnetic shielding heat dissipation film disclosed in the present invention is a film that is coated with a mixture of MXene nanosheets, boron nitride nanotubes, epoxy resin, and 3,3'-diamino-4,4'-difluorodiphenyl sulfone to form a functional enhancement layer. MXene nanosheets have good electrical conductivity and electromagnetic shielding properties, and can work in conjunction with the electromagnetic shielding layer to further enhance the overall shielding effect; boron nitride nanotubes have high thermal conductivity and chemical stability, which not only enhances the heat dissipation capacity, but also improves the mechanical strength and corrosion resistance of the material; epoxy resin is used as a matrix material, and after curing with 3,3'-diamino-4,4'-difluorodiphenyl sulfone, the functional enhancement layer is tightly combined with the gradient shielding layer to form a stable overall structure. This functional enhancement layer gives the electromagnetic shielding heat dissipation film more performance advantages besides heat dissipation and shielding, such as better mechanical properties and chemical stability, which broadens the application scenarios of the material.

[0031] (6) The preparation method of the electromagnetic shielding heat dissipation film disclosed in the present invention organically combines multiple processes such as in-situ growth, magnetron sputtering, coating curing and hot melt bonding. Each step cooperates with each other and works together to improve the performance of the final product. Compared with the existing preparation process, this method not only achieves high performance, but also has good process controllability and repeatability, which is conducive to large-scale industrial production. The layers are bonded to the polyimide film by hot-melt polyurethane adhesive at 150°C and 0.5MPa for 28-32 minutes, so that the layers are tightly bonded, the interface thermal resistance and contact resistance are reduced, the stability and reliability of the electromagnetic shielding heat dissipation film in practical applications are guaranteed, and the practicality and market competitiveness of the product are enhanced. DETAILED DESCRIPTION

[0032] The following description is intended to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments described below are only examples, and those skilled in the art may conceive of other obvious variations. Example 1

[0033] An electromagnetic shielding and heat dissipation film comprises, from top to bottom, a base layer, a three-dimensional thermal conductive network layer, a gradient electromagnetic shielding layer, and a function-enhancing layer; the function-enhancing layer is made of the following raw materials, calculated in parts by weight: 4 parts of MXene nanosheets, 3 parts of boron nitride nanotubes, 100 parts of epoxy resin, and 5 parts of 3,3'-diamino-4,4'-difluorodiphenyl sulfone.

[0034] The MXene nanosheets are titanium carbide MXene multilayer nanosheets with a thickness of 100-200 nm and a sheet diameter of 2-10 μm; the boron nitride nanotubes have a length of 10-20 μm and an average diameter of 50 nm; the epoxy resin is epoxy resin E-51; the base layer is made of polyimide film with a thickness of 50 μm; and the function enhancement layer has a thickness of 25 μm.

[0035] A method for preparing the electromagnetic shielding and heat dissipation film comprises the following steps: Step S1, in situ growth of a GNP-CNTs three-dimensional thermal conductive network: graphene nanosheets are dispersed in ethanol, filtered to form a GNP film with a thickness of 2 μm, and then dried and placed in a CVD reactor; iron nanoparticles are sputtered on the surface of the graphene nanosheets as a catalyst; a mixture of acetylene and argon is introduced and reacted at 680°C for 1.8 hours to in situ grow a CNT array; the sample is placed in an argon atmosphere at 2880°C and hot pressed for 7 hours to form covalent bonds between the GNPs and the CNTs to form a three-dimensional thermal conductive network layer; Step S2, gradient electromagnetic shielding layer deposition: using magnetron sputtering to deposit an Ag layer on the surface of the three-dimensional thermal conductive network layer; adjusting the target material ratio to deposit an Ag-Ni alloy layer; replacing the Ni target to deposit a Ni layer to form a gradient structure; Step S3, coating the function-enhancing layer: dispersing MXene nanosheets in N-methylpyrrolidone, adding boron nitride nanotubes, mixing, adding epoxy resin and 3,3'-diamino-4,4'-difluorodiphenyl sulfone, and stirring evenly; coating the mixture on the surface of the gradient shielding layer, and curing to obtain the function-enhancing layer; Step S4, molding: using hot-melt polyurethane adhesive to adhere the above structure to the polyimide film, and hot-pressing at 150° C. and 0.5 MPa for 28 minutes to form an electromagnetic shielding and heat dissipation film.

[0036] The graphene nanosheets in step S1 have a diameter of 5-10 μm and a thickness of 3-10 nm; the molar ratio of the graphene nanosheets to ethanol in step S1 is 1 mg:1 mL; the iron nanoparticles in step S1 have a particle size of 5-10 nm; the sputtering power is 50 W, and the sputtering time is 10 minutes; the mixed gas is a mixture of acetylene and argon in a volume ratio of 1:10; the CNTs array is perpendicular to the GNP surface, has a diameter of 10-15 nm, and is 500-800 μm in length.

[0037] The power for depositing the Ag layer in step S2 is 200 W, the pressure is 0.4 Pa, and the time is 30 min; the thickness of the Ag layer is 2 μm; the power for depositing the Ag-Ni alloy layer in step S2 is 250 W, the pressure is 0.5 Pa, and the time is 40 min; the mass ratio of Ag and Ni in the target material is 8:2; the thickness of the Ag-Ni alloy layer is 3 μm; the power for depositing the Ni layer in step S2 is 150 W, the pressure is 0.3 Pa, the time is 20 min, and the thickness of the Ni layer is 1 μm.

[0038] The molar ratio of MXene nanosheets to N-methylpyrrolidone in step S3 is 0.5 mg:1 mL. The curing conditions in step S3 are: first curing at 120° C. for 2 h, and then curing at 180° C. for 3 h. The hot-melt polyurethane adhesive in step S4 is TYFORCE FH-3000. Example 2

[0039] An electromagnetic shielding and heat dissipation film comprises, from top to bottom, a base layer, a three-dimensional thermal conductive network layer, a gradient electromagnetic shielding layer, and a function-enhancing layer; the function-enhancing layer is made of the following raw materials, calculated by weight: 4.5 parts of MXene nanosheets, 3.5 parts of boron nitride nanotubes, 100 parts of epoxy resin, and 6 parts of 3,3'-diamino-4,4'-difluorodiphenyl sulfone.

[0040] The MXene nanosheets are titanium carbide MXene multilayer nanosheets with a thickness of 100-200 nm and a sheet diameter of 2-10 μm; the boron nitride nanotubes have a length of 10-20 μm and an average diameter of 50 nm; the epoxy resin is epoxy resin E-51; the base layer is made of polyimide film with a thickness of 50 μm; and the function enhancement layer has a thickness of 25 μm.

[0041] A method for preparing the electromagnetic shielding and heat dissipation film comprises the following steps: Step S1, in situ growth of a three-dimensional GNP-CNT thermal network: graphene nanosheets are dispersed in ethanol, filtered to form a 3 μm thick GNP film, dried, and placed in a CVD reactor; iron nanoparticles are sputtered on the surface of the graphene nanosheets as a catalyst; a mixture of acetylene and argon is introduced, reacted at 690°C for 1.9 hours, and a CNT array is grown in situ; the sample is placed in an argon atmosphere at 2890°C and hot-pressed for 7.5 hours to form covalent bonds between the GNPs and the CNTs, forming a three-dimensional thermal network layer; Step S2, gradient electromagnetic shielding layer deposition: using magnetron sputtering to deposit an Ag layer on the surface of the three-dimensional thermal conductive network layer; adjusting the target material ratio to deposit an Ag-Ni alloy layer; replacing the Ni target to deposit a Ni layer to form a gradient structure; Step S3, coating the function-enhancing layer: dispersing MXene nanosheets in N-methylpyrrolidone, adding boron nitride nanotubes, mixing, adding epoxy resin and 3,3'-diamino-4,4'-difluorodiphenyl sulfone, and stirring evenly; coating the mixture on the surface of the gradient shielding layer, and curing to obtain the function-enhancing layer; Step S4, molding: using hot-melt polyurethane adhesive to adhere the above structure to the polyimide film, and hot-pressing at 150° C. and 0.5 MPa for 29 minutes to form an electromagnetic shielding and heat dissipation film.

[0042] The graphene nanosheets in step S1 have a diameter of 5-10 μm and a thickness of 3-10 nm; the molar ratio of the graphene nanosheets to ethanol in step S1 is 1 mg:1 mL; the iron nanoparticles in step S1 have a particle size of 5-10 nm; the sputtering power is 50 W, and the sputtering time is 10 minutes; the mixed gas is a mixture of acetylene and argon in a volume ratio of 1:10; the CNTs array is perpendicular to the GNP surface, has a diameter of 10-15 nm, and is 500-800 μm in length.

[0043] The power for depositing the Ag layer in step S2 is 200 W, the pressure is 0.4 Pa, and the time is 30 min; the thickness of the Ag layer is 2 μm; the power for depositing the Ag-Ni alloy layer in step S2 is 250 W, the pressure is 0.5 Pa, and the time is 40 min; the mass ratio of Ag and Ni in the target material is 8:2; the thickness of the Ag-Ni alloy layer is 3 μm; the power for depositing the Ni layer in step S2 is 150 W, the pressure is 0.3 Pa, the time is 20 min, and the thickness of the Ni layer is 1 μm.

[0044] The molar ratio of MXene nanosheets to N-methylpyrrolidone in step S3 is 0.5 mg:1 mL. The curing conditions in step S3 are: first curing at 120° C. for 2 h, and then curing at 180° C. for 3 h. The hot-melt polyurethane adhesive in step S4 is TYFORCE FH-3000. Example 3

[0045] An electromagnetic shielding and heat dissipation film comprises, from top to bottom, a base layer, a three-dimensional thermal conductive network layer, a gradient electromagnetic shielding layer, and a function-enhancing layer; the function-enhancing layer is made of the following raw materials, calculated in parts by weight: 5 parts of MXene nanosheets, 4 parts of boron nitride nanotubes, 100 parts of epoxy resin, and 6.5 parts of 3,3'-diamino-4,4'-difluorodiphenyl sulfone.

[0046] The MXene nanosheets are titanium carbide MXene multilayer nanosheets with a thickness of 100-200 nm and a sheet diameter of 2-10 μm; the boron nitride nanotubes have a length of 10-20 μm and an average diameter of 50 nm; the epoxy resin is epoxy resin E-51; the base layer is made of polyimide film with a thickness of 50 μm; and the function enhancement layer has a thickness of 25 μm.

[0047] A method for preparing the electromagnetic shielding and heat dissipation film comprises the following steps: Step S1, in situ growth of a three-dimensional GNP-CNT thermal network: graphene nanosheets are dispersed in ethanol, filtered to form a GNP film with a thickness of 3.5 μm, and then dried and placed in a CVD reactor; iron nanoparticles are sputtered on the surface of the graphene nanosheets as a catalyst; a mixture of acetylene and argon is introduced and reacted at 700°C for 2 hours to in situ grow a CNT array; the sample is placed in an argon atmosphere at 2900°C and hot pressed for 8 hours to form covalent bonds between the GNPs and the CNTs to form a three-dimensional thermal network layer; Step S2, gradient electromagnetic shielding layer deposition: using magnetron sputtering to deposit an Ag layer on the surface of the three-dimensional thermal conductive network layer; adjusting the target material ratio to deposit an Ag-Ni alloy layer; replacing the Ni target to deposit a Ni layer to form a gradient structure; Step S3, coating the function-enhancing layer: dispersing MXene nanosheets in N-methylpyrrolidone, adding boron nitride nanotubes, mixing, adding epoxy resin and 3,3'-diamino-4,4'-difluorodiphenyl sulfone, and stirring evenly; coating the mixture on the surface of the gradient shielding layer, and curing to obtain the function-enhancing layer; Step S4, molding: using hot-melt polyurethane adhesive to adhere the above structure to the polyimide film, and hot-pressing at 150° C. and 0.5 MPa for 30 minutes to form an electromagnetic shielding and heat dissipation film.

[0048] The graphene nanosheets in step S1 have a diameter of 5-10 μm and a thickness of 3-10 nm; the molar ratio of the graphene nanosheets to ethanol in step S1 is 1 mg:1 mL; the iron nanoparticles in step S1 have a particle size of 5-10 nm; the sputtering power is 50 W, and the sputtering time is 10 minutes; the mixed gas is a mixture of acetylene and argon in a volume ratio of 1:10; the CNTs array is perpendicular to the GNP surface, has a diameter of 10-15 nm, and is 500-800 μm in length.

[0049] The power for depositing the Ag layer in step S2 is 200 W, the pressure is 0.4 Pa, and the time is 30 min; the thickness of the Ag layer is 2 μm; the power for depositing the Ag-Ni alloy layer in step S2 is 250 W, the pressure is 0.5 Pa, and the time is 40 min; the mass ratio of Ag and Ni in the target material is 8:2; the thickness of the Ag-Ni alloy layer is 3 μm; the power for depositing the Ni layer in step S2 is 150 W, the pressure is 0.3 Pa, the time is 20 min, and the thickness of the Ni layer is 1 μm.

[0050] The molar ratio of MXene nanosheets to N-methylpyrrolidone in step S3 is 0.5 mg:1 mL. The curing conditions in step S3 are: first curing at 120° C. for 2 h, and then curing at 180° C. for 3 h. The hot-melt polyurethane adhesive in step S4 is TYFORCE FH-3000. Example 4

[0051] An electromagnetic shielding and heat dissipation film comprises, from top to bottom, a base layer, a three-dimensional thermal conductive network layer, a gradient electromagnetic shielding layer, and a function-enhancing layer; the function-enhancing layer is made of the following raw materials, calculated in parts by weight: 5.5 parts of MXene nanosheets, 4.5 parts of boron nitride nanotubes, 100 parts of epoxy resin, and 7.5 parts of 3,3'-diamino-4,4'-difluorodiphenyl sulfone.

[0052] The MXene nanosheets are titanium carbide MXene multilayer nanosheets with a thickness of 100-200 nm and a sheet diameter of 2-10 μm; the boron nitride nanotubes have a length of 10-20 μm and an average diameter of 50 nm; the epoxy resin is epoxy resin E-51; the base layer is made of polyimide film with a thickness of 50 μm; and the function enhancement layer has a thickness of 25 μm.

[0053] A method for preparing the electromagnetic shielding and heat dissipation film comprises the following steps: Step S1, in situ growth of a three-dimensional GNP-CNT thermal network: graphene nanosheets are dispersed in ethanol, filtered to form a 4 μm thick GNP film, dried, and placed in a CVD reactor; iron nanoparticles are sputtered on the surface of the graphene nanosheets as a catalyst; a mixture of acetylene and argon is introduced, reacted at 710°C for 2.1 hours, and a CNT array is grown in situ; the sample is placed in an argon atmosphere at 2905°C and hot-pressed for 8.5 hours to form covalent bonds between the GNPs and the CNTs, forming a three-dimensional thermal network layer; Step S2, gradient electromagnetic shielding layer deposition: using magnetron sputtering to deposit an Ag layer on the surface of the three-dimensional thermal conductive network layer; adjusting the target material ratio to deposit an Ag-Ni alloy layer; replacing the Ni target to deposit a Ni layer to form a gradient structure; Step S3, coating the function-enhancing layer: dispersing MXene nanosheets in N-methylpyrrolidone, adding boron nitride nanotubes, mixing, adding epoxy resin and 3,3'-diamino-4,4'-difluorodiphenyl sulfone, and stirring evenly; coating the mixture on the surface of the gradient shielding layer, and curing to obtain the function-enhancing layer; Step S4, molding: using hot-melt polyurethane adhesive to adhere the above structure to the polyimide film, and hot-pressing at 150° C. and 0.5 MPa for 31 minutes to form an electromagnetic shielding and heat dissipation film.

[0054] The graphene nanosheets in step S1 have a diameter of 5-10 μm and a thickness of 3-10 nm; the molar ratio of the graphene nanosheets to ethanol in step S1 is 1 mg:1 mL; the iron nanoparticles in step S1 have a particle size of 5-10 nm; the sputtering power is 50 W, and the sputtering time is 10 minutes; the mixed gas is a mixture of acetylene and argon in a volume ratio of 1:10; the CNTs array is perpendicular to the GNP surface, has a diameter of 10-15 nm, and is 500-800 μm in length.

[0055] The power for depositing the Ag layer in step S2 is 200 W, the pressure is 0.4 Pa, and the time is 30 min; the thickness of the Ag layer is 2 μm; the power for depositing the Ag-Ni alloy layer in step S2 is 250 W, the pressure is 0.5 Pa, and the time is 40 min; the mass ratio of Ag and Ni in the target material is 8:2; the thickness of the Ag-Ni alloy layer is 3 μm; the power for depositing the Ni layer in step S2 is 150 W, the pressure is 0.3 Pa, the time is 20 min, and the thickness of the Ni layer is 1 μm.

[0056] The molar ratio of MXene nanosheets to N-methylpyrrolidone in step S3 is 0.5 mg:1 mL. The curing conditions in step S3 are: first curing at 120° C. for 2 h, and then curing at 180° C. for 3 h. The hot-melt polyurethane adhesive in step S4 is TYFORCE FH-3000. Example 5

[0057] An electromagnetic shielding and heat dissipation film comprises, from top to bottom, a base layer, a three-dimensional thermal conductive network layer, a gradient electromagnetic shielding layer, and a function-enhancing layer; the function-enhancing layer is made of the following raw materials, calculated in parts by weight: 6 parts of MXene nanosheets, 5 parts of boron nitride nanotubes, 100 parts of epoxy resin, and 8 parts of 3,3'-diamino-4,4'-difluorodiphenyl sulfone.

[0058] The MXene nanosheets are titanium carbide MXene multilayer nanosheets with a thickness of 100-200 nm and a sheet diameter of 2-10 μm; the boron nitride nanotubes have a length of 10-20 μm and an average diameter of 50 nm; the epoxy resin is epoxy resin E-51; the base layer is made of polyimide film with a thickness of 50 μm; and the function enhancement layer has a thickness of 25 μm.

[0059] A method for preparing the electromagnetic shielding and heat dissipation film comprises the following steps: Step S1, in situ growth of a three-dimensional GNP-CNT thermal conductive network: graphene nanosheets are dispersed in ethanol, filtered to form a 5 μm thick GNP film, dried, and placed in a CVD reactor; iron nanoparticles are sputtered on the surface of the graphene nanosheets as a catalyst; a mixture of acetylene and argon is introduced and reacted at 720°C for 2.2 hours to in situ grow a CNT array; the sample is placed in an argon atmosphere at 2910°C and hot-pressed for 9 hours to form covalent bonds between the GNPs and the CNTs to form a three-dimensional thermal conductive network layer; Step S2, gradient electromagnetic shielding layer deposition: using magnetron sputtering to deposit an Ag layer on the surface of the three-dimensional thermal conductive network layer; adjusting the target material ratio to deposit an Ag-Ni alloy layer; replacing the Ni target to deposit a Ni layer to form a gradient structure; Step S3, coating the function-enhancing layer: dispersing MXene nanosheets in N-methylpyrrolidone, adding boron nitride nanotubes, mixing, adding epoxy resin and 3,3'-diamino-4,4'-difluorodiphenyl sulfone, and stirring evenly; coating the mixture on the surface of the gradient shielding layer, and curing to obtain the function-enhancing layer; Step S4, molding: using hot-melt polyurethane adhesive to adhere the above structure to the polyimide film, and hot-pressing at 150° C. and 0.5 MPa for 32 minutes to form an electromagnetic shielding and heat dissipation film.

[0060] The graphene nanosheets in step S1 have a diameter of 5-10 μm and a thickness of 3-10 nm; the molar ratio of the graphene nanosheets to ethanol in step S1 is 1 mg:1 mL; the iron nanoparticles in step S1 have a particle size of 5-10 nm; the sputtering power is 50 W, and the sputtering time is 10 minutes; the mixed gas is a mixture of acetylene and argon in a volume ratio of 1:10; the CNTs array is perpendicular to the GNP surface, has a diameter of 10-15 nm, and is 500-800 μm in length.

[0061] The power for depositing the Ag layer in step S2 is 200 W, the pressure is 0.4 Pa, and the time is 30 min; the thickness of the Ag layer is 2 μm; the power for depositing the Ag-Ni alloy layer in step S2 is 250 W, the pressure is 0.5 Pa, and the time is 40 min; the mass ratio of Ag and Ni in the target material is 8:2; the thickness of the Ag-Ni alloy layer is 3 μm; the power for depositing the Ni layer in step S2 is 150 W, the pressure is 0.3 Pa, the time is 20 min, and the thickness of the Ni layer is 1 μm.

[0062] The molar ratio of MXene nanosheets to N-methylpyrrolidone in step S3 is 0.5 mg:1 mL. The curing conditions in step S3 are: first curing at 120° C. for 2 h, and then curing at 180° C. for 3 h. The hot-melt polyurethane adhesive in step S4 is TYFORCE FH-3000.

[0063] Comparative Example 1 An electromagnetic shielding and heat dissipation film, a preparation method thereof, and an application thereof are basically the same as those in Example 1, except that an equal amount of MXene nanosheets is used instead of boron nitride nanotubes, and no Ag-Ni alloy layer is deposited.

[0064] Comparative Example 2 An electromagnetic shielding and heat dissipation film, a preparation method thereof, and an application thereof are basically the same as Example 1, except that an equal amount of boron nitride nanotubes is used instead of MXene nanosheets, and no Ni layer is deposited.

[0065] In order to further illustrate the beneficial technical effects of the electromagnetic shielding and heat dissipation films involved in each embodiment of the present invention, relevant performance tests were carried out on the electromagnetic shielding and heat dissipation films involved in Examples 1-5 and Comparative Examples 1-2. The test results are shown in Table 1. The test method is as follows: Referring to GB / T 30142-2013 "Measurement Method for Shielding Effectiveness of Planar Electromagnetic Shielding Materials", a vector network analyzer was used to test the electromagnetic shielding effectiveness of each electromagnetic shielding and heat dissipation film in the frequency range of 30MHz-40GHz; the thermal conductivity was tested using the LFA 427 laser thermal conductivity meter using the ASTM-E1461 standard; bending test: after 10,000 bends with a curvature radius of 3mm, the electromagnetic shielding effectiveness was tested again, and the attenuation of the electromagnetic shielding effectiveness was calculated.

[0066] As can be seen from Table 1, the electromagnetic shielding and heat dissipation film disclosed in the embodiment of the present invention has better electromagnetic shielding and heat dissipation performance than the comparative example product, and better mechanical stability; the combined use of MXene nanosheets, boron nitride nanotubes deposited Ag-Ni alloy layer and deposited Ni layer is beneficial to improving the above performance.

[0067] Table 1 project Average shielding effectiveness Thermal conductivity Average electromagnetic shielding effectiveness attenuation unit dB W / m·K % Example 1 73.0 1660 ＜2.5 Example 2 73.5 1682 ＜2.2 Example 3 73.8 1700 ＜1.8 Example 4 74.6 1735 ＜1.0 Example 5 75.5 1750 ＜0.7 Comparative Example 1 65.4 1480 ＞8.6 Comparative Example 2 67.9 1520 ＞7.2 The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. An electromagnetic shielding and heat dissipation film, characterized in that: From top to bottom, it includes a base layer, a three-dimensional thermal conductive network layer, a gradient electromagnetic shielding layer, and a function enhancement layer; the function enhancement layer is made of the following raw materials in parts by weight: 4-6 parts of MXene nanosheets, 3-5 parts of boron nitride nanotubes, 100 parts of epoxy resin, and 5-8 parts of 3,3'-diamino-4,4'-difluorodiphenyl sulfone.

2. The electromagnetic shielding and heat dissipation film according to claim 1, characterized in that: The MXene nanosheets are titanium carbide MXene multilayer nanosheets with a thickness of 100-200 nm and a sheet diameter of 2-10 μm; the boron nitride nanotubes have a length of 10-20 μm and an average diameter of 50 nm; and the epoxy resin is epoxy resin E-51.

3. The electromagnetic shielding and heat dissipation film according to claim 1, characterized in that: The base layer is made of a polyimide film with a thickness of 50-100 μm; the function enhancement layer has a thickness of 25-35 μm; and the gradient electromagnetic shielding layer has a thickness of 6-9 μm.

4. A method for preparing an electromagnetic shielding and heat dissipation film according to any one of claims 1 to 3, characterized in that: The steps include: Step S1, in situ growth of a three-dimensional GNP-CNT thermal conductive network: graphene nanosheets are dispersed in ethanol, filtered to form a GNP film with a thickness of 2-5 μm, and then dried and placed in a CVD reactor; iron nanoparticles are sputtered on the surface of the graphene nanosheets as a catalyst; a mixture of acetylene and argon is introduced and reacted at 680-720°C for 1.8-2.2 hours to in situ grow a CNT array; the sample is placed in an argon atmosphere at 2880-2910°C and hot pressed for 7-9 hours to form covalent bonds between the GNPs and the CNTs to form a three-dimensional thermal conductive network layer; Step S2, gradient electromagnetic shielding layer deposition: using magnetron sputtering to deposit an Ag layer on the surface of the three-dimensional thermal conductive network layer; adjusting the target material ratio to deposit an Ag-Ni alloy layer; replacing the Ni target to deposit a Ni layer to form a gradient structure; Step S3, coating the function-enhancing layer: dispersing MXene nanosheets in N-methylpyrrolidone, adding boron nitride nanotubes, mixing, adding epoxy resin and 3,3'-diamino-4,4'-difluorodiphenyl sulfone, and stirring evenly; coating the mixture on the surface of the gradient shielding layer, and curing to obtain the function-enhancing layer; Step S4, molding: using hot-melt polyurethane adhesive to adhere the above structure to the polyimide film, hot pressing at 150° C. and 0.5 MPa for 28-32 minutes to form an electromagnetic shielding and heat dissipation film.

5. The method for preparing the electromagnetic shielding and heat dissipation film according to claim 4, characterized in that: The graphene nanosheets in step S1 have a diameter of 5-10 μm and a thickness of 3-10 nm; the amount ratio of the graphene nanosheets to ethanol in step S1 is 1 mg:1 mL.

6. The method for preparing the electromagnetic shielding and heat dissipation film according to claim 4, characterized in that: The iron nanoparticles in step S1 have a particle size of 5-10 nm; the sputtering power is 50 W, and the sputtering time is 10 minutes; the mixed gas is a mixture of acetylene and argon at a volume ratio of 1:10; the CNTs array is perpendicular to the GNP surface, has a diameter of 10-15 nm, and a length of 500-800 μm.

7. The method for preparing the electromagnetic shielding and heat dissipation film according to claim 4, characterized in that: The power for depositing the Ag layer in step S2 is 200 W, the pressure is 0.4 Pa, and the time is 30 min; the thickness of the Ag layer is 2-3 μm; the power for depositing the Ag-Ni alloy layer in step S2 is 250 W, the pressure is 0.5 Pa, and the time is 40 min; the mass ratio of Ag and Ni in the target material is 8:2; the thickness of the Ag-Ni alloy layer is 3-4 μm.

8. The method for preparing the electromagnetic shielding and heat dissipation film according to claim 4, wherein: In step S2 , the power for depositing the Ni layer is 150 W, the pressure is 0.3 Pa, the time is 20 min, and the thickness of the Ni layer is 1-2 μm.

9. The method for preparing the electromagnetic shielding and heat dissipation film according to claim 4, wherein: The molar ratio of MXene nanosheets to N-methylpyrrolidone in step S3 is 0.5 mg:1 mL. The curing conditions in step S3 are: first curing at 120° C. for 2 h, and then curing at 180° C. for 3 h. The hot-melt polyurethane adhesive in step S4 is TYFORCE FH-3000.

10. Use of the electromagnetic shielding and heat dissipation film according to any one of claims 1 to 3 in the field of electronic equipment.