Electromagnetic shielding composite material with stretchable conductive ability, preparation method and application

Abstract

The present invention discloses an electromagnetic shielding composite material with stretchable conductivity, as well as its preparation method and application. Specifically, the stretchable, conductive electromagnetic shielding composite material is a three-layer sandwich structure composite material consisting of two upper and lower resin layers containing solid metal powder, and a central resin layer containing liquid metal. The electromagnetic shielding material of the present invention exhibits excellent electrical conductivity and electromagnetic shielding performance in both its initial state and in its stretched state.

Description

Technical Field

[0001] The invention relates to an electromagnetic shielding composite material with stretchable conductive capability and a preparation method thereof. Background Art

[0002] With the rapid development of mobile phones, laptops, and other portable electronic products, miniaturization, portability, multi-functions, low energy consumption, and high reliability have become the constant pursuit of electronic devices. Flexible devices, in particular, have seen rapid development in recent years, with devices such as flexible screens and electronic skin already widely used in real life. Polymer-based electromagnetic shielding materials, due to their thinness, bendability, rollability, and foldability, perfectly align with the trend toward thinness and miniaturization in flexible devices and are an important means of addressing the electromagnetic shielding issues faced by these devices.

[0003] In the use of electronic devices, flexible devices are often subjected to external forces such as stretching, causing them to deform. To reduce electromagnetic wave leakage and ensure the normal operation of the device, electromagnetic shielding materials must maintain good electromagnetic shielding performance even in the stretched and deformed state. In highly integrated packaging, electromagnetic shielding materials will deform to varying degrees to adapt to the shape of the package module. In this case, stable tensile conductivity is also required to maintain electromagnetic shielding performance. Therefore, the development of a material with stable tensile conductivity and good electromagnetic shielding performance in the stretched state is an urgent problem to be solved.

[0004] Patent CN202111323569.8 discloses an ultra-sensitive, resistive-responsive stretchable conductive composite fiber, its preparation method, and application. Using parallel helical elastic fibers as a stretchable substrate and carbon nanotube nanocomposites as conductive materials, a conductive composite fiber with excellent stretchability and resistive responsiveness is prepared. This conductive composite fiber can be used as a fiber-shaped resistive strain sensor, accurately and sensitively capturing physiological signals of the human body and varying degrees of strain caused by joint movement. This simple manufacturing strategy is expected to be used for the large-scale preparation of ultra-sensitive conductive composite fibers and wearable strain sensing materials. However, the conductivity and electromagnetic shielding properties of carbon materials are lower than those of metal materials.

[0005] Patent CN202110914909.8 discloses a liquid metal fiber / elastomer flexible composite material and its preparation method and application. The method comprises the following steps: adding liquid metal to an elastomer solution to obtain a liquid metal / elastomer mixture; subjecting the obtained liquid metal / elastomer mixture to magnetic stirring to obtain a liquid metal fiber / elastomer mixed emulsion; centrifuging the obtained product, and taking one-third of the middle layer as a casting stock solution; pouring and drying the casting stock solution, and then heating and curing it to obtain a liquid metal fiber / elastomer flexible composite material. This method achieves a combination of light weight, flexibility, high thermal conductivity and high electromagnetic shielding effectiveness. However, the conductivity of liquid metal is low in its initial state, and leakage will occur during the stretching process, which has a significant impact on the conductivity after stretching. Therefore, how to reasonably use liquid metal and give full play to its advantages is a problem that needs to be solved. Summary of the Invention

[0006] In view of this, in order to overcome the above-mentioned defects and problems, the present invention provides a low-cost, simple-process electromagnetic shielding composite material with stretchable conductivity and a preparation method thereof. The electromagnetic shielding material has excellent conductivity and electromagnetic shielding performance both in the initial state and during the stretching process.

[0007] One aspect of the present invention provides an electromagnetic shielding composite material with tensile conductivity, which is a three-layer sandwich structure consisting of two upper and lower metal powder resin layers and a liquid metal resin layer in the middle; the metal powder resin layer contains metal powder and resin matrix material, and the liquid metal resin layer contains liquid metal and resin matrix material.

[0008] Preferably, the thickness of the upper and lower metal powder resin layers is about 20μm to 200μm; more preferably 40μm-150μm, for example, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm.

[0009] Preferably, the thickness of the liquid metal resin layer is about 20 μm to 200 μm; more preferably, 40 μm to 120 μm, for example, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, or 120 μm.

[0010] Preferably, the mass ratio of metal powder to resin in the metal powder resin layer is 1:1-9:1; more preferably 4:1-9:1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1.

[0011] Preferably, the mass fractions of liquid metal and resin in the liquid metal resin layer are 1:1-9:1, more preferably 4:1-9:1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1.

[0012] Preferably, the metal powder is selected from elemental metal powder and metal-plated powder, and the elemental metal powder is selected from powders of gold, silver, copper, nickel and aluminum; the metal-plated powder is selected from any one or more combinations of silver-plated copper powder, gold-plated copper powder, silver-plated nickel powder, gold-plated nickel powder, silver-plated glass fiber powder, nickel-plated glass fiber powder and nickel-plated graphite powder.

[0013] Preferably, the liquid metal is an alloy that is liquid at room temperature. The liquid metal is preferably an alloy of one or more of gallium, bismuth, indium, tin, zirconium and zinc, including gallium-based liquid metal and zirconium-based liquid metal; preferably tin-zinc alloy, bismuth-indium-tin alloy, bismuth-indium-tin-zinc alloy, gallium-indium-tin-zinc alloy, gallium-indium-tin-zinc alloy or gallium-tin-zinc alloy.

[0014] Preferably, the liquid metal is pretreated before being dispersed into the matrix material. The pretreatment is to disperse the liquid metal into microspheres with a diameter of 500 nm-50 μm in a solvent by mechanical force. More preferably, the dispersion method is ultrasound or mechanical stirring.

[0015] Preferably, the material of the resin matrix is ​​selected from thermosetting resins and thermoplastic resins;

[0016] The thermosetting resin includes any one or more of epoxy resin, polyester resin, vinyl ester, bismaleimide, polyimide, cyanate ester, and organosiloxane;

[0017] The thermoplastic resin includes any one or more combinations of polyester, acrylic resin, polyether, polyurethane, styrene elastomer, polycarbonate, butadiene rubber, polyisoprene, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyoxymethylene, polycarbonate, polyphenylene ether, polysulfone, and fiber.

[0018] In a second aspect, the present invention provides a method for preparing the electromagnetic shielding material described in the first aspect, the preparation method comprising the following steps:

[0019] Step 1: dissolving the resin matrix material in an organic solvent to form a resin solution;

[0020] Step 2: mixing the metal powder and the pretreated liquid metal with the resin solution respectively to obtain a metal powder conductive paste and a liquid metal conductive paste;

[0021] Step 3: Applying metal powder conductive paste on the release film and drying to obtain a bottom metal powder resin layer;

[0022] Applying liquid metal conductive paste on the bottom metal powder resin layer and drying to obtain a liquid metal resin layer;

[0023] Then, the metal powder conductive slurry is coated on the liquid metal resin layer and dried to obtain the electromagnetic shielding material;

[0024] The pretreatment is to disperse the liquid metal in a solvent by mechanical force; preferably, the liquid metal is dispersed into microspheres with a diameter of 500nm-50μm, and more preferably, the dispersion method is ultrasound or mechanical stirring.

[0025] Preferably, in step 1, the organic solvent comprises any one or a combination of at least two of an aromatic hydrocarbon organic solvent, an aliphatic hydrocarbon organic solvent, an alicyclic hydrocarbon organic solvent, an ester organic solvent, a ketone organic solvent or an amide organic solvent;

[0026] Preferably, the organic solvent comprises any one or a combination of at least two of N,N-dimethylformamide, benzene, toluene, cyclohexanone, tetrahydrofuran, dioxane, ethyl acetate, butanone, and acetone;

[0027] Preferably, the drying method in step 3 includes one or more combinations of heating, negative pressure or normal pressure evaporation of solvent;

[0028] Preferably, the heating temperature in step 3 is in the range of 60-150°C;

[0029] Preferably, the heating time is independently 10 min-4 h.

[0030] In a third aspect, the present invention provides a use of the electromagnetic shielding material with tensile conductive properties described in the first aspect in preparing electromagnetic shielding materials for electronic devices.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. The sandwich structure electromagnetic shielding material of the present invention has two layers, the upper and lower layers, of metal powder resin, and the middle layer is a liquid metal resin layer. It has excellent electrical conductivity and electromagnetic shielding performance in both the initial state and the stretched state.

[0033] 2. The upper and lower metal powder resin layers in the sandwich structure electromagnetic shielding material of the present invention can effectively reduce the leakage of liquid metal during the stretching process, ensuring the stability of the conductive performance during the stretching process;

[0034] 3. The sandwich structure electromagnetic shielding material of the present invention is primarily conductive by the upper and lower metal layers in its initial state. In a low tensile strain state, both the upper and lower metal powder resin layers and the middle liquid metal resin layer are conductive. In a high tensile strain state, the middle liquid metal resin layer primarily provides conductivity, and the upper and lower metal powder resin layers primarily form a conductive path in the thickness direction.

[0035] 4. The sandwich structure electromagnetic shielding material of the present invention has tight bonding between different layers and has conductive properties in the thickness direction;

[0036] 5. The electromagnetic shielding material of the present invention exhibits excellent flexibility, high elongation at break, and can withstand large deformations such as stretching, bending, folding, winding, and twisting;

[0037] 6. The preparation method of the present invention is simple, easy and low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the cross-sectional SEM image of the stretchable electromagnetic shielding material.

[0039] Figure 2 This is the tensile-electrical performance curve of stretchable electromagnetic shielding material.

[0040] Figure 3 Schematic diagram of the conductive path during stretching. In the unstretched state, the upper and lower metal powder-containing resin layers exhibit good in-plane conductivity, while the middle liquid metal-containing resin layer exhibits only weak conductivity due to the lack of interconnection between the liquid metal particles. However, due to the presence of the metal powder-containing resin layers on both sides, the composite material as a whole exhibits high in-plane conductivity and electromagnetic shielding performance. Under a slight stretch (200%), as the middle layer stretches, the liquid metal in the resin comes into contact with each other, forming a conductive path. The metal powder in the upper and lower metal powder-containing resin layers also interconnects, resulting in a three-layer stack with high electromagnetic shielding performance. Further stretching further reduces the metal powder in the upper and lower resin layers due to the stretching, resulting in reduced conductivity and electromagnetic shielding performance. However, the liquid metal in the middle layer maintains good conductivity and electromagnetic shielding effectiveness. The upper and lower metal powder resin layers primarily form a conductive path in the thickness direction, ensuring reliable electrical connection and grounding between the shielding material and the other substrate, thereby ensuring the reliability of the shielding Faraday cage.

[0041] Figure 4 This is the electromagnetic shielding performance curve of the stretchable electromagnetic shielding material in different states. DETAILED DESCRIPTION

[0042] The solution of the present invention will be described with reference to the accompanying drawings. Figure 1 As shown, the present invention provides an electromagnetic shielding composite material with tensile conductive ability, which is a three-layer sandwich structure consisting of two upper and lower metal powder resin layers and a liquid metal resin layer in the middle. The metal powder resin layer is a thin layer containing metal powder and having resin as a matrix, and the liquid metal resin layer is a thin layer containing liquid metal particles and having resin as a matrix.

[0043] The two metal powder layers not only provide excellent conductivity in their initial state, but also reduce leakage of liquid metal from the middle layer during the stretching process. When the liquid metal microspheres in the middle liquid metal layer are squeezed during stretching, the liquid metal reforms into continuous interconnected channels, providing high conductivity and effective electromagnetic shielding during the stretching process.

[0044] The thickness of the upper and lower metal powder resin layers is about 20μm to 200μm, more preferably 40μm-150μm, for example 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm.

[0045] The thickness of the liquid metal resin layer is about 20 μm to 200 μm; 20 μm to 200 μm; more preferably 40 μm to 120 μm, for example, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm.

[0046] The mass fractions of silver powder and resin in the resin layer containing metal powder are 50-95% and 5-50% respectively;

[0047] The mass fractions of liquid metal and resin in the liquid metal-containing resin layer are 50-95% and 5-50% respectively;

[0048] The metal powder is selected from elemental metal powder and metal-plated powder, wherein the elemental metal powder is selected from powders of gold, silver, copper, nickel and aluminum; the metal-plated powder is selected from any one or more combinations of silver-plated copper powder, gold-plated copper powder, silver-plated nickel powder, gold-plated nickel powder, silver-plated glass fiber powder, nickel-plated glass fiber powder and nickel-plated graphite powder;

[0049] The liquid metal material is an alloy that is liquid at room temperature. The liquid metal is preferably an alloy of one or more of gallium, bismuth, indium, tin, zirconium and zinc, more preferably selected from gallium-based liquid metal and zirconium-based liquid metal; most preferably tin-zinc alloy, bismuth-indium-tin alloy, bismuth-indium-tin-zinc alloy, gallium-indium-tin-zinc alloy, gallium-indium-tin-zinc alloy, gallium-indium-tin alloy or gallium-tin-zinc alloy.

[0050] The liquid metal material is first mechanically dispersed in a solvent before being mixed with the resin to form microspheres with a diameter of 500 nm to 50 μm. Preferably, the dispersion method is ultrasound or mechanical stirring.

[0051] More preferably, the solvent includes any one or more combinations of water, N,N-dimethylformamide, benzene, toluene, cyclohexanone, tetrahydrofuran, dioxane, ethyl acetate, butanone, and acetone.

[0052] The resin matrix material includes thermosetting resin and thermoplastic resin;

[0053] The thermosetting resin includes any one or more of epoxy resin, polyester resin, vinyl ester, bismaleimide, polyimide, cyanate ester, and organosiloxane;

[0054] The thermoplastic resin includes any one or more combinations of polyester, acrylic resin, polyether, polyurethane, styrene elastomer, polycarbonate, butadiene rubber, polyisoprene, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyoxymethylene, polycarbonate, polyphenylene ether, polysulfone, and fiber.

[0055] The resin in the metal powder resin layer and the liquid metal resin layer is preferably the same resin.

[0056] The present invention also provides a method for preparing an electromagnetic shielding material, the preparation method comprising the following steps:

[0057] Step 1: dissolving the resin matrix material in an organic solvent to form a resin solution;

[0058] Step 2: mixing the metal powder and the pretreated liquid metal dispersion with the resin solution to obtain a metal powder conductive paste and a liquid metal conductive paste;

[0059] Step 3: Applying metal powder conductive paste on the release film and drying to obtain a bottom metal powder resin layer;

[0060] Applying liquid metal conductive paste on the bottom metal powder resin layer and drying to obtain a liquid metal resin layer;

[0061] Then, the metal powder conductive slurry is coated on the liquid metal resin layer and dried to obtain the electromagnetic shielding material.

[0062] The step-by-step coating preparation method adopted in the present invention has the advantages of simple operation and low cost. The three layers of the prepared stretchable electromagnetic shielding material are tightly bonded, have no obvious defects, and have conductive properties in the in-plane direction and thickness direction.

[0063] In step 1, the organic solvent includes any one or a combination of at least two of an aromatic hydrocarbon organic solvent, an aliphatic hydrocarbon organic solvent, an alicyclic hydrocarbon organic solvent, an ester organic solvent, a ketone organic solvent or an amide organic solvent;

[0064] The organic solvent includes any one or a combination of at least two of N,N-dimethylformamide, benzene, toluene, cyclohexanone, tetrahydrofuran, dioxane, ethyl acetate, butanone, and acetone;

[0065] The drying method in step 3 includes heating and / or negative pressure drying;

[0066] The heating temperature in step 3 is in the range of 60-150°C;

[0067] The heating time is independently 10 min-4 h.

[0068] The present invention provides an application of the electromagnetic shielding material with tensile conductive properties described in the first aspect in electronic equipment.

[0069] Example 1:

[0070] This embodiment provides an electromagnetic shielding material. The electromagnetic shielding material is composed of two upper and lower metal powder resin layers and a middle layer of a liquid metal resin layer.

[0071] The thickness of the upper and lower metal powder-containing resin layers is 50 μm, and the mass fractions of the metal powder and the resin are 80% and 20% respectively. The metal powder is flaky silver powder with a diameter of about 1 to 5 μm. The resin is thermoplastic polyurethane purchased from BASF with a brand name 1185A10;

[0072] The resin layer containing liquid metal has a thickness of 80 μm and is composed of 90% liquid metal and 10% resin by mass. The liquid metal is gallium-indium alloy liquid metal (the mass ratio of gallium to indium is 3:1). The resin is thermoplastic polyurethane purchased from BASF with the brand name 1185A10.

[0073] The preparation method of the electromagnetic shielding material comprises the following steps:

[0074] Step 1: Dissolution of resin material

[0075] Thermoplastic polyurethane particles and N,N-dimethylformamide solvent were mixed, and heated and stirred for 12 hours using a magnetic stirrer at a heating temperature of 60° C. to obtain a thermoplastic polyurethane / N,N-dimethylformamide solution with a thermoplastic polyurethane mass fraction of 25 wt %.

[0076] Step 2: preparing metal powder conductive slurry and liquid metal conductive slurry;

[0077] Flake silver powder was mixed with a thermoplastic polyurethane / N,N-dimethylformamide solution to prepare a mixed solution with a mass ratio of silver powder to thermoplastic polyurethane of 8:2; liquid metal was added to an N,N-dimethylformamide solvent (mass ratio of 1:5) and ultrasonically treated with a cell disruptor at an ultrasonic power of 30W and an ultrasonic time of 5 minutes. The ultrasonically dispersed liquid metal dispersion was then mixed with a thermoplastic polyurethane / N,N-dimethylformamide solution to prepare a mixed solution with a mass ratio of liquid metal to thermoplastic polyurethane of 9:1. The above two mixed solutions were respectively mixed by rotating a mixer for 5 minutes at a speed of 2000r / min to obtain a metal powder conductive slurry and a liquid metal conductive slurry;

[0078] Step 3: Prepare electromagnetic shielding materials

[0079] A uniformly stirred silver powder / thermoplastic polyurethane conductive paste was knife-coated onto a release film and the solvent was dried at 100°C for 1 hour. Next, a liquid metal / thermoplastic polyurethane conductive paste was knife-coated onto the dried silver powder / thermoplastic polyurethane film and the solvent was dried at 100°C for 1 hour. Finally, a silver powder / thermoplastic polyurethane conductive paste was knife-coated onto the dried liquid metal / thermoplastic polyurethane film and the solvent was dried at 100°C for 4 hours to obtain a sandwich composite electromagnetic shielding film.

[0080] Example 2: This example provides an electromagnetic shielding material comprising two upper and lower metal powder resin layers and a middle layer of liquid metal resin. The upper and lower metal powder resin layers are 100 μm thick, with the metal powder and resin comprising 80% by mass and 20% by mass, respectively. The liquid metal resin layer is 50 μm thick, with the liquid metal and resin comprising 90% by mass and 10% by mass, respectively. Otherwise, the material is identical to Example 1.

[0081] Example 3:

[0082] This embodiment provides an electromagnetic shielding material comprising two upper and lower metal powder resin layers and a middle layer of liquid metal resin. The upper and lower metal powder resin layers are 50 μm thick, with the mass fractions of metal powder and resin being 70% and 30%, respectively. The liquid metal resin layer is 80 μm thick, with the mass fractions of liquid metal and resin being 80% and 20%, respectively. Otherwise, the material is identical to that of Example 1.

[0083] Comparative Example 1:

[0084] The difference between this comparative example and Example 1 is that it does not contain a liquid metal resin layer, but a separate metal powder resin material, the thickness of which is equivalent to the total thickness of the material in Example 1, and the use of metal powder and resin and the amount of component addition are the same as those of the metal powder resin layer in Example 1.

[0085] Comparative Example 2:

[0086] The difference between this comparative example and Example 1 is that it does not contain a metal powder resin layer, but a single liquid metal resin material, the thickness of which is equivalent to the total thickness of the material in Example 1, and the use of liquid metal and resin and the amount of component addition are the same as those of the liquid metal resin layer in Example 1.

[0087] Effect Examples

[0088] 1. Performance testing

[0089] The elongation at break, resistance in the initial state and in the stretched state, and electromagnetic shielding performance of Examples 1-3 and Comparative Example 1 were tested respectively.

[0090] Table 1

[0091]

[0092]

[0093] The experimental results are shown in Table 1. These results demonstrate that despite the three-layer structure of the present invention, with different metal types within the three layers, this does not affect its tensile properties, achieving elongation at break similar to that of a single-layer structure. The resistance and electromagnetic shielding data demonstrate that the present invention achieves low resistivity and high electromagnetic shielding performance in both the unstretched and stretched states, particularly achieving excellent electromagnetic shielding performance.

[0094] 2Scanning electron microscopy

[0095] The interface structure characteristics of electromagnetic shielding materials were observed by scanning electron microscopy. The experimental results are shown in Figure 1 The experimental results show that the electromagnetic shielding material invented in this case has a significant three-layer structural feature, and the three layers of different resins are tightly bonded.

[0096] 3 Tensile-electrical performance curve

[0097] Electrodes were attached to both ends of a standard-sized sample (50 mm × 10 mm). The tensile properties were tested at a speed of 50 mm / min using a universal testing machine, and the resistance change was monitored simultaneously.

[0098] The experimental results are shown in Figure 2

[0099] 4 Electromagnetic shielding performance curve

[0100] The electromagnetic shielding performance curves of the product of Example 1 under different stretching states were tested respectively. The experimental results are shown in Figure 3 ,pass Figure 3 It can be seen that the electromagnetic shielding effectiveness is essentially the same in the initial state and at a stretch rate of 100%, indicating that at low-intensity stretching, the present invention can achieve almost the same shielding efficiency as in the unstretched state, and when stretched to 200%, it can also achieve a high electromagnetic shielding efficiency. Stretching rates below 200% are already sufficient for most current applications. The experimental results show that the product of the present invention not only achieves efficient stretching, but also maintains no degradation in performance parameters after stretching.

[0101] Although the present invention is disclosed above with reference to preferred embodiments, they are not intended to limit the present invention. Anyone with ordinary knowledge in the technical field may make slight changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the patent application defined in the claims.

Claims

1. An electromagnetic shielding material with tensile conductive properties, characterized in that: It consists of a three-layer sandwich structure consisting of two metal powder resin layers and a liquid metal resin layer in the middle; the metal powder resin layer contains metal powder and resin matrix material, and the liquid metal resin layer contains liquid metal and resin matrix material; The preparation method of the electromagnetic shielding material with tensile conductive properties comprises the following steps: Step 1: dissolving the resin material in an organic solvent to form a resin solution; Step 2: mixing the metal powder and the pretreated liquid metal dispersion with the resin solution to obtain a metal powder conductive paste and a liquid metal conductive paste; Step 3: Applying the metal powder conductive slurry on the release film and drying it to obtain a bottom metal powder resin layer; Applying liquid metal conductive paste on the bottom metal powder resin layer and drying to obtain a liquid metal resin layer; Then, the metal powder conductive slurry is coated on the liquid metal resin layer and dried to obtain the electromagnetic shielding material; The pretreatment is to disperse the liquid metal in a solvent by mechanical force.

2. The electromagnetic shielding material with tensile conductive properties according to claim 1, characterized in that: The thickness of the metal powder resin layer is 20 to 200 μm.

3. The electromagnetic shielding material with tensile conductive properties according to claim 2, characterized in that: The thickness of the liquid metal resin layer is 20 to 200 μm.

4. The electromagnetic shielding material with tensile conductive properties according to any one of claims 1 to 3, characterized in that: The mass ratio of metal powder to resin in the metal powder resin layer is 1:1-9:1 respectively; The mass fractions of liquid metal and resin in the liquid metal resin layer are 1:1-9:1 respectively.

5. The electromagnetic shielding material with tensile conductive properties according to claim 4, wherein the mass ratio of metal powder to resin in the metal powder resin layer is 4:1-9:1; The mass fractions of liquid metal and resin in the liquid metal resin layer are 4:1-9:1 respectively.

6. The electromagnetic shielding material with tensile conductive properties according to any one of claims 1 to 3, characterized in that: The metal powder is selected from elemental metal powder and metal-plated powder.

7. The electromagnetic shielding material with tensile conductive properties according to claim 6, characterized in that: The elemental metal powder is selected from powders of gold, silver, copper, nickel and aluminum.

8. The electromagnetic shielding material with tensile conductive properties according to claim 6, characterized in that: The metal-plated powder is selected from any one or more combinations of silver-plated copper powder, gold-plated copper powder, silver-plated nickel powder, gold-plated nickel powder, silver-plated glass fiber powder, nickel-plated glass fiber powder, and nickel-plated graphite powder.

9. The electromagnetic shielding material with tensile conductive properties according to any one of claims 1 to 3, characterized in that: The liquid metal is an alloy that is liquid at room temperature.

10. The electromagnetic shielding material with tensile conductive properties according to claim 9, characterized in that: The liquid metal is an alloy of multiple types selected from gallium, bismuth, indium, tin, zirconium and zinc.

11. The electromagnetic shielding material with tensile conductive properties according to claim 10, characterized in that: The liquid metal is selected from gallium-based liquid metal and zirconium-based liquid metal.

12. The electromagnetic shielding material with tensile conductive properties according to claim 10, characterized in that: The liquid metal is selected from tin-zinc alloy, bismuth-indium-tin alloy, bismuth-indium-tin-zinc alloy, gallium-indium-tin-zinc alloy, gallium-indium-tin alloy or gallium-tin-zinc alloy.

13. The electromagnetic shielding material with tensile conductive properties according to claim 9, characterized in that: The liquid metal material is first mechanically dispersed in a solvent before being mixed with the resin to form microspheres with a diameter of 500nm-50μm.

14. The electromagnetic shielding material with tensile conductive properties according to claim 13, characterized in that: The solvent includes any one or more combinations of water, N,N-dimethylformamide, benzene, toluene, cyclohexanone, tetrahydrofuran, dioxane, ethyl acetate, butanone, and acetone.

15. The electromagnetic shielding material with tensile conductive properties according to any one of claims 1 to 3, characterized in that: Resin matrix materials include thermosetting resins and thermoplastic resins.

16. The electromagnetic shielding material with tensile conductive properties according to claim 15, characterized in that: The thermosetting resin includes any one or more of epoxy resin, polyester resin, vinyl ester, bismaleimide, polyimide, cyanate ester, and organosiloxane.

17. The electromagnetic shielding material with tensile conductive properties according to claim 16, characterized in that: The thermoplastic resin includes any one or more combinations of polyester, acrylic resin, polyether, polyurethane, styrene elastomer, polycarbonate, butadiene rubber, polyisoprene, polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyoxymethylene, polycarbonate, polyphenylene ether, polysulfone, and fiber.

18. The method for preparing the electromagnetic shielding material with tensile conductive properties according to any one of claims 1 to 17, characterized in that: The preparation steps include: Step 1: dissolving the resin material in an organic solvent to form a resin solution; Step 2: mixing the metal powder and the pretreated liquid metal dispersion with the resin solution to obtain a metal powder conductive paste and a liquid metal conductive paste; Step 3: Applying the metal powder conductive slurry on the release film and drying it to obtain a bottom metal powder resin layer; Applying liquid metal conductive paste on the bottom metal powder resin layer and drying to obtain a liquid metal resin layer; Then, the metal powder conductive slurry is coated on the liquid metal resin layer and dried to obtain the electromagnetic shielding material; The pretreatment is to disperse the liquid metal in a solvent by mechanical force.

19. The preparation method according to claim 18, characterized in that The liquid metal is dispersed into microspheres with a diameter of 500nm-50μm.

20. The preparation method according to claim 18, characterized in that The dispersion methods are ultrasound and mechanical stirring.

21. The preparation method according to claim 18, characterized in that In step 1, the organic solvent is selected from any one or a combination of at least two of aromatic hydrocarbon organic solvents, aliphatic hydrocarbon organic solvents, alicyclic hydrocarbon organic solvents, ester organic solvents, ketone organic solvents or amide organic solvents.

22. The preparation method according to claim 21, characterized in that The organic solvent is selected from any one of N,N-dimethylformamide, benzene, toluene, cyclohexanone, tetrahydrofuran, dioxane, ethyl acetate, butanone, and acetone, or a combination of at least two thereof.

23. The preparation method according to any one of claims 18 to 22, characterized in that: The drying method in step 3 includes one or more combinations of heating, negative pressure or normal pressure evaporation of the solvent.

24. The preparation method according to claim 23, characterized in that The heating temperature in step 3 is in the range of 60-150°C.

25. The preparation method according to claim 24, characterized in that The heating time is independently 10 min-4 h.

26. Use of the electromagnetic shielding material with tensile conductive properties according to any one of claims 1 to 17 in preparing electromagnetic shielding materials for electronic devices.

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