A shielding cover based on silicone rubber conductive adhesive and a preparation method thereof

Abstract

The application relates to the technical field of electromagnetic shielding materials, in particular to a shielding cover based on a silicon rubber conductive glue and a preparation method thereof. An aluminum-magnesium alloy raw material is pressure-cast to form a shielding shell; a composite magnetic adhesive, a silver-carrying copper conductive composite adhesive and a silver-carrying conductive composite adhesive are sequentially spot-coated at fixed positions of the shielding cover, vulcanization and packaging are carried out, and a finished product is obtained. The finished product prepared by the application has excellent electromagnetic shielding performance, so that the application has a wide application prospect in the technical field of electromagnetic shielding materials.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic shielding materials technology, specifically a shielding cover based on silicone rubber conductive adhesive and its preparation method. Background Technology

[0002] In today's rapidly developing technological world, electronic devices permeate every corner of our lives. Shielding covers, as a key component of these devices, are playing an indispensable role in modern life. With the increasing power of electronic devices, their internal electronic components are densely packed and operate at extremely high speeds, making electromagnetic interference a particularly challenging problem. Shielding covers based on conductive silicone rubber can effectively block mutual interference of electromagnetic signals, creating a clean operating environment for electronic components. Taking smartphones as an example, shielding covers ensure that various chip modules do not interfere with each other, resulting in stable signals and smooth operation during calls, internet browsing, and gaming, greatly enhancing the user experience.

[0003] However, with the increasing integration of electronic devices, numerous electronic components are densely packed together. The complex electromagnetic signals generated by these components during operation can cause interference, leading to performance degradation, data transmission errors, signal loss, and malfunctions. Applying conductive silicone rubber to fixed locations on the shielding cover effectively prevents signal leakage from the gaps, thus more effectively blocking electromagnetic interference. This ensures the independent and stable operation of each component within the electronic device, guaranteeing its overall performance and reliability.

[0004] To overcome the shortcomings of the prior art, the present invention provides a shielding cover based on silicone rubber conductive adhesive and its preparation method. Summary of the Invention

[0005] The purpose of this invention is to provide a shielding cover based on silicone rubber conductive adhesive and its preparation method, so as to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing a shielding cover based on silicone rubber conductive adhesive includes the following steps: aluminum-magnesium alloy raw material is die-cast to obtain a shielding shell; composite magnetic adhesive, silver-copper conductive composite adhesive, and silver conductive composite adhesive are sequentially applied to a fixed position on the shielding cover; the cover is vulcanized at 100-120℃ for 30-40 minutes; and then packaged to obtain the finished product.

[0008] In a more optimized manner, by weight, 20-25 parts of composite magnetic material, 50-60 parts of vinyl polysiloxane, 8-10 parts of hydrogen-containing polysiloxane, 0.02-0.03 parts of chloroplatinic acid, and 0.02-0.03 parts of methylpentynol are mixed to obtain a composite magnetic adhesive; 20-25 parts of silver-copper conductive composite material, 50-60 parts of vinyl polysiloxane, 8-10 parts of hydrogen-containing polysiloxane, 0.02-0.03 parts of chloroplatinic acid, and 0.02-0.03 parts of methylpentynol are mixed to obtain a silver-copper conductive composite adhesive; and 20-25 parts of silver-conductive composite material, 50-60 parts of vinyl polysiloxane, 8-10 parts of hydrogen-containing polysiloxane, 0.02-0.03 parts of chloroplatinic acid, and 0.02-0.03 parts of methylpentynol are mixed to obtain a silver-conductive composite adhesive.

[0009] The optimized preparation process for silver-loaded conductive composite materials and silver-loaded copper conductive composite materials is as follows:

[0010] Step S1: Add polymethyl methacrylate powder to deionized water to obtain a polymethyl methacrylate solution; then add Ti3C2T X MXene powder was added to a polymethyl methacrylate solution and stirred thoroughly for 25-30 minutes. After stirring, the mixture was centrifuged to obtain a composite material. The composite material and graphene oxide were then added to deionized water and stirred thoroughly under argon atmosphere for 3-4 hours. After freeze-drying, a conductive composite material was obtained. The conductive composite material was then heat-treated under argon atmosphere at 440-450℃ for 1.2-1.5 hours to obtain a porous conductive composite material.

[0011] Step S2: Add silver nitrate to deionized water to obtain silver nitrate solution; then add porous conductive composite material, ultrasonically disperse for 20-30 min, then add ethylene glycol, continue ultrasonic dispersion for 15-20 min, after uniform dispersion, react in a water bath at 35-40℃ for 15-20 h, after the reaction is completed, cool, centrifuge, wash and dry to obtain silver-loaded conductive composite material.

[0012] Step S3: Add polyvinyl alcohol to deionized water to obtain a polyvinyl alcohol solution; add silver nitrate to deionized water to obtain a silver nitrate solution; add copper nitrate trihydrate to deionized water to obtain a copper nitrate solution; mix the silver nitrate solution and the copper nitrate solution, stir evenly, then add the porous conductive composite material, ultrasonically disperse for 20-30 min, then add the polyvinyl alcohol solution, continue ultrasonic dispersion for 15-20 min, after even dispersion, react in a water bath at 80-90℃ for 1.0-1.5 h, after the reaction is completed, cool, centrifuge, wash, and dry to obtain the silver-copper conductive composite material.

[0013] In a more optimized manner, in step S1, polymethyl methacrylate powder and Ti3C2TX The mass ratio of MXene powder to graphene oxide is (6-7):1:(4-5).

[0014] In a more optimized manner, in step S2, when preparing the silver-loaded conductive composite material, the mass-to-volume ratio of silver nitrate, porous conductive composite material, and ethylene glycol is (0.35-0.40) g: 2.5 g: 20 mL.

[0015] In a more optimized manner, in step S3, the reaction mass ratio of silver nitrate, copper nitrate trihydrate, porous conductive composite material, and polyvinyl alcohol is 0.15:(0.075-0.078):1.8:7.5.

[0016] A more optimized preparation process for composite magnetic materials is as follows:

[0017] Step S1: Add xylose to deionized water to obtain a 0.45-0.50 mol / L xylose solution; heat-treat the xylose solution at 180-200℃ for 11-13 h; after the reaction is completed, cool, filter, wash, and dry to obtain carbon microspheres.

[0018] Step S2: Add carbon microspheres to deionized water and add sodium hydroxide to adjust the pH to 11.0-11.2 to obtain a carbon microsphere solution; add nickel nitrate hexahydrate and ferric nitrate nonahydrate to deionized water to obtain a salt solution; add the salt solution dropwise to the carbon microsphere solution, and after the dropwise addition is complete, add urea and ammonium fluoride, and after ultrasonic dispersion, react at 110-120℃ for 11-13 hours. After the reaction is complete, cool, wash and dry to obtain a carbon microsphere-hydrotalcite composite material.

[0019] Step S3: Add ferrous sulfate heptahydrate and ferric nitrate nonahydrate to deionized water and stir thoroughly to obtain an iron salt solution; then add carbon microsphere-hydrotalcite composite material, deionized water, and the iron salt solution, disperse evenly by ultrasonication, add sodium hydroxide to adjust the pH to 10.0-10.2, and react in a water bath at 80-85℃ for 20-30 minutes. After the reaction is completed, cool, wash, and dry to obtain the composite magnetic material.

[0020] In a more optimized manner, in step S2, the reaction mass ratio of carbon microspheres, nickel nitrate hexahydrate, ferric nitrate nonahydrate, urea, and ammonium fluoride is (0.08-0.1):0.22:0.1:0.35:0.08.

[0021] In a more optimized manner, in step S3, the reaction mass ratio of ferrous sulfate heptahydrate, ferric nitrate nonahydrate, and carbon microsphere-hydrotalcite composite material is 0.07:0.17:(0.02-0.03).

[0022] The beneficial effects of this invention are:

[0023] The invention is characterized by the addition of polymethyl methacrylate and Ti3C2T X MXene powder and graphene oxide were used to obtain a conductive composite material. After high-temperature heat treatment, polymethyl methacrylate (PMMA) decomposed, and graphene oxide underwent thermal reduction, thus transforming the conductive composite material into a porous conductive composite material. This porous structure significantly increases the specific surface area of ​​the material, providing more propagation paths and reflection interfaces for electromagnetic waves within the material. When electromagnetic waves enter the porous structure, they are continuously reflected and scattered between the pore walls, thereby consuming a large amount of energy. Furthermore, the conductive material reduces graphene oxide to Ti3C2T... X The interweaving of MXenes can form a conductive network within the composite material.

[0024] Furthermore, by adding porous conductive composite materials, ethylene glycol, and silver nitrate, a silver-loaded conductive composite material was obtained through chemical reduction. The silver-loaded conductive composite material, vinyl polysiloxane, hydrogen-containing polysiloxane, chloroplatinic acid, and methylpentynol were then mixed to obtain a silver-loaded conductive composite adhesive. Based on the porous conductive composite material, silver was introduced by adding ethylene glycol and silver nitrate and using a chemical reduction method. Silver is a metal with excellent conductivity; the uniform distribution of silver particles in the pores and surface of the porous conductive composite material further enhances its conductivity. The interaction of silver particles with the porous structure and other conductive components further increases the opportunities for electromagnetic wave scattering and absorption within the material.

[0025] Furthermore, by adding porous conductive composite materials, polyvinyl alcohol, silver nitrate, and copper nitrate trihydrate, and then performing an in-situ reduction method under water bath heating, a silver-copper conductive composite material was obtained. A silver-copper conductive composite adhesive was then obtained by mixing the silver-copper conductive composite material, vinyl polysiloxane, hydrogen-containing polysiloxane, chloroplatinic acid, and methylpentynol. Both silver and copper are metals with excellent conductivity, and they are uniformly distributed in the pores and surface of the porous conductive composite material. This not only further improves the material's conductivity and enhances its ability to reflect electromagnetic waves, but also allows the silver and copper nanoparticles to synergistically interact with the porous structure and other components, increasing the opportunities for electromagnetic wave scattering and absorption within the material.

[0026] The invention is characterized by the following: a carbon microsphere-hydrotalcite composite material is obtained by adding xylose, nickel nitrate hexahydrate, ferric nitrate nonahydrate, urea, and ammonium fluoride; a composite magnetic material is obtained by coating the surface of the carbon microsphere-hydrotalcite composite material with ferrous sulfate heptahydrate and ferric nitrate nonahydrate, thereby adding the carbon microsphere-hydrotalcite composite material, ferric oxide, and ferric nitrate nonahydrate. A composite magnetic adhesive is obtained by mixing the composite magnetic material, vinyl polysiloxane, hydrogen-containing polysiloxane, chloroplatinic acid, and methylpentynol.

[0027] The carbon microspheres possess a certain degree of electrical conductivity, while the nickel and iron ions in the hydrotalcite structure endow the material with a certain degree of magnetism. Furthermore, iron(III) oxide (Fe3O4) is a strongly magnetic material, and its coating significantly enhances the magnetism of the entire composite magnetic material. Magnetic materials can interact with the magnetic field components of electromagnetic waves, generating hysteresis loss and eddy current loss, converting the energy of electromagnetic waves into heat energy, thereby achieving effective absorption of electromagnetic waves. Therefore, this composite magnetic adhesive, through the fundamental characteristics of the carbon microsphere-hydrotalcite composite material, the reinforcing effect of the composite magnetic material, and the synergistic effect of each component in the adhesive, forms a highly efficient electromagnetic shielding system, thus possessing excellent electromagnetic shielding performance.

[0028] A shielding shell is obtained by die-casting aluminum-magnesium alloy raw materials. Then, a composite magnetic adhesive, a silver-copper conductive composite adhesive, and a silver-copper conductive composite adhesive are sequentially applied to fixed positions on the shielding cover. After vulcanization and packaging, a shielding cover based on silicone rubber conductive adhesive is obtained. The advantages of this adhesive structure are: firstly, the composite magnetic adhesive is applied, utilizing its unique magnetic microstructure and electromagnetic properties to preferentially interact with external electromagnetic waves, efficiently absorbing electromagnetic wave energy and converting it into heat and other forms of energy, achieving preliminary processing of electromagnetic waves. Then, on the basis of the already coated composite magnetic adhesive, the silver-copper conductive composite adhesive is applied. Due to the presence of metallic silver, copper, and Ti3C2T... X MXene powder and reduced graphene oxide exhibit excellent conductivity, resulting in a highly conductive adhesive that forms a conductive network within it. When electromagnetic waves remaining after absorption by the composite magnetic adhesive enter this adhesive layer, they are repeatedly reflected within this conductive network. Each reflection involves energy loss, achieving multiple reflections and attenuation, further reducing the intensity of the electromagnetic waves. Finally, a silver-loaded conductive composite adhesive is applied. This adhesive has moderate conductivity and further processes the electromagnetic waves after multiple reflections and attenuation by the silver-copper conductive composite adhesive. Similarly, through multiple reflections within the adhesive layer, the energy of the electromagnetic waves is further dissipated, achieving secondary, multiple-reflection attenuation.

[0029] In summary, the finished product prepared by this invention has excellent electromagnetic shielding performance, and therefore has broad application prospects in the field of electromagnetic shielding materials technology. Detailed Implementation

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Raw material source:

[0032] Polymethyl methacrylate powder, supplied by Ruixiang Plastics Co., Ltd., with an average microsphere diameter of 3 μm; Ti3C2T X MXene powder, provided by Forsmann Technology (Beijing) Co., Ltd., model number 2203006; graphene oxide, provided by Changzhou Yaobang Friction Material Factory, particle size 2nm; polyvinyl alcohol, provided by Kaimaoxing (Hebei) Cellulose Co., Ltd., molecular weight 120,000; xylose, provided by Henan Qinuo Food Ingredients Co., Ltd., XOS-35; hydrogen-containing polysiloxane, provided by Shandong Qimin Chemical Technology Co., Ltd., molecular weight 222.5; vinyl polysiloxane, provided by Shandong Huachen New Material Co., Ltd., model number HC04; by mass, one part is 1g.

[0033] Example 1: Step S1: Polymethyl methacrylate powder is added to deionized water to obtain a polymethyl methacrylate solution; then Ti3C2T X MXene powder was added to a polymethyl methacrylate solution and stirred thoroughly for 30 minutes. After stirring, the mixture was centrifuged to obtain a composite material. The composite material and graphene oxide were then added to deionized water and stirred thoroughly under argon atmosphere for 4 hours. After freeze-drying, a conductive composite material was obtained. The conductive composite material was then heat-treated at 450℃ for 1.5 hours under argon atmosphere to obtain a porous conductive composite material. (The text then repeats the steps: polymethyl methacrylate powder, Ti3C2T...) X The mass ratio of MXene powder to graphene oxide was 6.5:1:4.5.

[0034] Step S2: Add silver nitrate to deionized water to obtain a silver nitrate solution; then add the porous conductive composite material, ultrasonically disperse for 30 min, then add ethylene glycol, continue ultrasonic dispersion for 20 min, and after uniform dispersion, react in a 40℃ water bath for 20 h. After the reaction is completed, cool, centrifuge, wash, and dry to obtain the silver-loaded conductive composite material; the mass-volume ratio of silver nitrate, porous conductive composite material, and ethylene glycol is 0.37 g: 2.5 g: 20 mL.

[0035] Step S3: Polyvinyl alcohol is added to deionized water to obtain a polyvinyl alcohol solution; silver nitrate is added to deionized water to obtain a silver nitrate solution; copper nitrate trihydrate is added to deionized water to obtain a copper nitrate solution; the silver nitrate solution and copper nitrate solution are mixed and stirred evenly before adding the porous conductive composite material. After ultrasonic dispersion for 30 min, the polyvinyl alcohol solution is added again, and ultrasonic dispersion is continued for 20 min. After even dispersion, the mixture is reacted in a 90℃ water bath for 1.5 h. After the reaction is completed, the mixture is cooled, centrifuged, washed, and dried to obtain the silver-copper conductive composite material. The reaction mass ratio of silver nitrate, copper nitrate trihydrate, porous conductive composite material, and polyvinyl alcohol is 0.15:0.076:1.8:7.5.

[0036] Step S4: Add xylose to deionized water to obtain a 0.50 mol / L xylose solution; heat-treat the xylose solution at 200℃ for 13 h; after the reaction is completed, cool, filter, wash, and dry to obtain carbon microspheres;

[0037] Step S5: Add carbon microspheres to deionized water and adjust the pH to 11.2 with sodium hydroxide to obtain a carbon microsphere solution; add nickel nitrate hexahydrate and ferric nitrate nonahydrate to deionized water to obtain a salt solution; add the salt solution dropwise to the carbon microsphere solution, and after the dropwise addition is complete, add urea and ammonium fluoride, disperse evenly by ultrasonication, and react at 120℃ for 13 hours. After the reaction is complete, cool, wash, and dry to obtain a carbon microsphere-hydrotalcite composite material; the reaction mass ratio of carbon microspheres, nickel nitrate hexahydrate, ferric nitrate nonahydrate, urea, and ammonium fluoride is 0.09:0.22:0.1:0.35:0.08;

[0038] Step S6: Add ferrous sulfate heptahydrate and ferric nitrate nonahydrate to deionized water, stir thoroughly to obtain an iron salt solution; then add carbon microsphere-hydrotalcite composite material, deionized water, and the mixture to the iron salt solution, ultrasonically disperse evenly, add sodium hydroxide to adjust the pH to 10.2, and react in a water bath at 85℃ for 30 minutes. After the reaction is complete, cool, wash, and dry to obtain the composite magnetic material; the reaction mass ratio of ferrous sulfate heptahydrate, ferric nitrate nonahydrate, and carbon microsphere-hydrotalcite composite material is 0.07:0.17:0.025.

[0039] Step S7: Mix 25g of composite magnetic material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a composite magnetic adhesive; mix 25g of silver-copper conductive composite material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a silver-copper conductive composite adhesive; mix 25g of silver-conductive composite material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a silver-conductive composite adhesive;

[0040] Aluminum-magnesium alloy raw materials are die-cast to obtain a shielding shell; composite magnetic adhesive, silver-copper conductive composite adhesive, and silver conductive composite adhesive are sequentially applied to the fixed position of the shielding cover, and after curing at 120℃ for 40 minutes and packaging, the finished product is obtained.

[0041] Example 2: Step S1: Add polymethyl methacrylate powder to deionized water to obtain a polymethyl methacrylate solution; then add Ti3C2T XMXene powder was added to a polymethyl methacrylate solution and stirred thoroughly for 27 minutes. After stirring, the mixture was centrifuged to obtain a composite material. The composite material and graphene oxide were then added to deionized water and stirred thoroughly under argon atmosphere for 3.5 hours. After freeze-drying, a conductive composite material was obtained. The conductive composite material was then heat-treated at 445℃ for 1.3 hours under argon atmosphere to obtain a porous conductive composite material. (The text then repeats the steps: polymethyl methacrylate powder, Ti3C2T...) X The mass ratio of MXene powder to graphene oxide was 6.5:1:4.5.

[0042] Step S2: Silver nitrate was added to deionized water to obtain a silver nitrate solution; then a porous conductive composite material was added, and ultrasonically dispersed for 25 min, followed by the addition of ethylene glycol, and ultrasonically dispersed for another 17 min. After uniform dispersion, the mixture was reacted in a water bath at 37°C for 17 h. After the reaction was completed, the mixture was cooled, centrifuged, washed, and dried to obtain the silver-loaded conductive composite material. The mass-to-volume ratio of silver nitrate, porous conductive composite material, and ethylene glycol was 0.37 g: 2.5 g: 20 mL.

[0043] Step S3: Polyvinyl alcohol was added to deionized water to obtain a polyvinyl alcohol solution; silver nitrate was added to deionized water to obtain a silver nitrate solution; copper nitrate trihydrate was added to deionized water to obtain a copper nitrate solution; the silver nitrate solution and copper nitrate solution were mixed and stirred evenly before adding the porous conductive composite material. After ultrasonic dispersion for 25 min, the polyvinyl alcohol solution was added, and ultrasonic dispersion was continued for 17 min. After even dispersion, the mixture was reacted in a water bath at 85℃ for 1.2 h. After the reaction was completed, the mixture was cooled, centrifuged, washed, and dried to obtain the silver-copper conductive composite material. The reaction mass ratio of silver nitrate, copper nitrate trihydrate, porous conductive composite material, and polyvinyl alcohol was 0.15:0.076:1.8:7.5.

[0044] Step S4: Add xylose to deionized water to obtain a 0.50 mol / L xylose solution; heat-treat the xylose solution at 190℃ for 12 h; after the reaction is completed, cool, filter, wash, and dry to obtain carbon microspheres.

[0045] Step S5: Add carbon microspheres to deionized water and adjust the pH to 11.1 with sodium hydroxide to obtain a carbon microsphere solution; add nickel nitrate hexahydrate and ferric nitrate nonahydrate to deionized water to obtain a salt solution; add the salt solution dropwise to the carbon microsphere solution, and after the dropwise addition is complete, add urea and ammonium fluoride, disperse evenly by ultrasonication, and react at 115℃ for 12 hours. After the reaction is complete, cool, wash, and dry to obtain a carbon microsphere-hydrotalcite composite material; the reaction mass ratio of carbon microspheres, nickel nitrate hexahydrate, ferric nitrate nonahydrate, urea, and ammonium fluoride is 0.09:0.22:0.1:0.35:0.08;

[0046] Step S6: Add ferrous sulfate heptahydrate and ferric nitrate nonahydrate to deionized water, stir thoroughly to obtain an iron salt solution; then add carbon microsphere-hydrotalcite composite material, deionized water, and the mixture to the iron salt solution, ultrasonically disperse evenly, add sodium hydroxide to adjust the pH to 10.1, and react in a water bath at 82℃ for 25 minutes. After the reaction is complete, cool, wash, and dry to obtain the composite magnetic material; the reaction mass ratio of ferrous sulfate heptahydrate, ferric nitrate nonahydrate, and carbon microsphere-hydrotalcite composite material is 0.07:0.17:0.025.

[0047] Step S7: Mix 25g of composite magnetic material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a composite magnetic adhesive; mix 25g of silver-copper conductive composite material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a silver-copper conductive composite adhesive; mix 25g of silver-conductive composite material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a silver-conductive composite adhesive;

[0048] Aluminum-magnesium alloy raw materials are die-cast to obtain a shielding shell; composite magnetic adhesive, silver-copper conductive composite adhesive, and silver conductive composite adhesive are sequentially applied to the fixed position of the shielding cover, and after curing at 110℃ for 35 minutes and packaging, the finished product is obtained.

[0049] Example 3: Step S1: Add polymethyl methacrylate powder to deionized water to obtain a polymethyl methacrylate solution; then add Ti3C2T X MXene powder was added to a polymethyl methacrylate solution and stirred thoroughly for 25 minutes. After stirring, the mixture was centrifuged to obtain a composite material. The composite material and graphene oxide were then added to deionized water and stirred thoroughly under argon atmosphere for 3 hours. After freeze-drying, a conductive composite material was obtained. The conductive composite material was then heat-treated at 440℃ for 1.2 hours under argon atmosphere to obtain a porous conductive composite material. (The text then repeats the steps: polymethyl methacrylate powder, Ti3C2T...) X The mass ratio of MXene powder to graphene oxide was 6.5:1:4.5.

[0050] Step S2: Add silver nitrate to deionized water to obtain a silver nitrate solution; then add the porous conductive composite material, ultrasonically disperse for 20 min, then add ethylene glycol, continue ultrasonic dispersion for 15 min, and after uniform dispersion, react in a 35℃ water bath for 15 h. After the reaction is completed, cool, centrifuge, wash, and dry to obtain the silver-loaded conductive composite material; the mass-volume ratio of silver nitrate, porous conductive composite material, and ethylene glycol is 0.37 g: 2.5 g: 20 mL.

[0051] Step S3: Polyvinyl alcohol is added to deionized water to obtain a polyvinyl alcohol solution; silver nitrate is added to deionized water to obtain a silver nitrate solution; copper nitrate trihydrate is added to deionized water to obtain a copper nitrate solution; the silver nitrate solution and copper nitrate solution are mixed and stirred evenly before adding the porous conductive composite material. After ultrasonic dispersion for 20 min, the polyvinyl alcohol solution is added, and ultrasonic dispersion is continued for 15 min. After even dispersion, the mixture is reacted in a water bath at 80℃ for 1.0 h. After the reaction is completed, the mixture is cooled, centrifuged, washed, and dried to obtain the silver-copper conductive composite material. The reaction mass ratio of silver nitrate, copper nitrate trihydrate, porous conductive composite material, and polyvinyl alcohol is 0.15:0.076:1.8:7.5.

[0052] Step S4: Add xylose to deionized water to obtain a 0.50 mol / L xylose solution; heat-treat the xylose solution at 180℃ for 11 h; after the reaction is completed, cool, filter, wash and dry to obtain carbon microspheres.

[0053] Step S5: Add carbon microspheres to deionized water and adjust the pH to 11 with sodium hydroxide to obtain a carbon microsphere solution; add nickel nitrate hexahydrate and ferric nitrate nonahydrate to deionized water to obtain a salt solution; add the salt solution dropwise to the carbon microsphere solution, and after the dropwise addition is complete, add urea and ammonium fluoride, disperse evenly by ultrasonication, and react at 110℃ for 11 hours. After the reaction is complete, cool, wash, and dry to obtain a carbon microsphere-hydrotalcite composite material; the reaction mass ratio of carbon microspheres, nickel nitrate hexahydrate, ferric nitrate nonahydrate, urea, and ammonium fluoride is 0.09:0.22:0.1:0.35:0.08;

[0054] Step S6: Add ferrous sulfate heptahydrate and ferric nitrate nonahydrate to deionized water, stir thoroughly to obtain an iron salt solution; then add carbon microsphere-hydrotalcite composite material, deionized water, and the mixture to the iron salt solution, ultrasonically disperse evenly, add sodium hydroxide to adjust the pH to 10, and react in an 80℃ water bath for 20 minutes. After the reaction is complete, cool, wash, and dry to obtain the composite magnetic material; the reaction mass ratio of ferrous sulfate heptahydrate, ferric nitrate nonahydrate, and carbon microsphere-hydrotalcite composite material is 0.07:0.17:0.025.

[0055] Step S7: Mix 25g of composite magnetic material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a composite magnetic adhesive; mix 25g of silver-copper conductive composite material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a silver-copper conductive composite adhesive; mix 25g of silver-conductive composite material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a silver-conductive composite adhesive;

[0056] Aluminum-magnesium alloy raw materials are die-cast to obtain a shielding shell; composite magnetic adhesive, silver-copper conductive composite adhesive, and silver conductive composite adhesive are sequentially applied to the fixed position of the shielding cover, and after curing at 100℃ for 30 minutes and packaging, the finished product is obtained.

[0057] Comparative Example 1: The silver-loaded conductive composite adhesive was removed, and the rest was the same as in Example 1. The specific steps are as follows: Step S1: Polymethyl methacrylate powder was added to deionized water to obtain a polymethyl methacrylate solution; then Ti3C2T X MXene powder was added to a polymethyl methacrylate solution and stirred thoroughly for 30 minutes. After stirring, the mixture was centrifuged to obtain a composite material. The composite material and graphene oxide were then added to deionized water and stirred thoroughly under argon atmosphere for 4 hours. After freeze-drying, a conductive composite material was obtained. The conductive composite material was then heat-treated at 450℃ for 1.5 hours under argon atmosphere to obtain a porous conductive composite material. (The text then repeats the steps: polymethyl methacrylate powder, Ti3C2T...) X The mass ratio of MXene powder to graphene oxide was 6.5:1:4.5.

[0058] Step S2: Polyvinyl alcohol was added to deionized water to obtain a polyvinyl alcohol solution; silver nitrate was added to deionized water to obtain a silver nitrate solution; copper nitrate trihydrate was added to deionized water to obtain a copper nitrate solution; the silver nitrate solution and copper nitrate solution were mixed and stirred evenly before adding the porous conductive composite material. After ultrasonic dispersion for 30 min, the polyvinyl alcohol solution was added again, and ultrasonic dispersion was continued for 20 min. After even dispersion, the mixture was reacted in a 90℃ water bath for 1.5 h. After the reaction was completed, the mixture was cooled, centrifuged, washed, and dried to obtain the silver-copper conductive composite material. The reaction mass ratio of silver nitrate, copper nitrate trihydrate, porous conductive composite material, and polyvinyl alcohol was 0.15:0.076:1.8:7.5.

[0059] Step S3: Add xylose to deionized water to obtain a 0.50 mol / L xylose solution; heat-treat the xylose solution at 200℃ for 13 h; after the reaction is completed, cool, filter, wash, and dry to obtain carbon microspheres;

[0060] Step S4: Add carbon microspheres to deionized water and adjust the pH to 11.2 with sodium hydroxide to obtain a carbon microsphere solution; add nickel nitrate hexahydrate and ferric nitrate nonahydrate to deionized water to obtain a salt solution; add the salt solution dropwise to the carbon microsphere solution, and after the dropwise addition is complete, add urea and ammonium fluoride, disperse evenly by ultrasonication, and react at 120℃ for 13 hours. After the reaction is complete, cool, wash, and dry to obtain a carbon microsphere-hydrotalcite composite material; the reaction mass ratio of carbon microspheres, nickel nitrate hexahydrate, ferric nitrate nonahydrate, urea, and ammonium fluoride is 0.09:0.22:0.1:0.35:0.08;

[0061] Step S5: Add ferrous sulfate heptahydrate and ferric nitrate nonahydrate to deionized water, stir thoroughly to obtain an iron salt solution; then add carbon microsphere-hydrotalcite composite material, deionized water, and the mixture to the iron salt solution, ultrasonically disperse evenly, add sodium hydroxide to adjust the pH to 10.2, and react in a water bath at 85℃ for 30 minutes. After the reaction is complete, cool, wash, and dry to obtain the composite magnetic material; the reaction mass ratio of ferrous sulfate heptahydrate, ferric nitrate nonahydrate, and carbon microsphere-hydrotalcite composite material is 0.07:0.17:0.025.

[0062] Step S6: Mix 25g of composite magnetic material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a composite magnetic adhesive; mix 25g of silver-copper conductive composite material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a silver-copper conductive composite adhesive;

[0063] Aluminum-magnesium alloy raw materials are die-cast to obtain a shielding shell; composite magnetic adhesive and silver-copper conductive composite adhesive are sequentially applied to the fixed position of the shielding cover, and after curing at 120℃ for 40 minutes and packaging, the finished product is obtained.

[0064] Comparative Example 2: The silver-copper conductive composite adhesive and the silver-loaded conductive composite adhesive were removed, and the rest was the same as in Example 1. The specific steps are as follows: Step S1: Xylose was added to deionized water to obtain a 0.50 mol / L xylose solution; the xylose solution was heat-treated at 200℃ for 13 h, and after the reaction was completed, it was cooled, filtered, washed and dried to obtain carbon microspheres;

[0065] Step S2: Carbon microspheres were added to deionized water, and sodium hydroxide was added to adjust the pH to 11.2 to obtain a carbon microsphere solution. Nickel nitrate hexahydrate and ferric nitrate nonahydrate were added to deionized water to obtain a salt solution. The salt solution was added dropwise to the carbon microsphere solution. After the addition was complete, urea and ammonium fluoride were added. After ultrasonic dispersion, the mixture was reacted at 120℃ for 13 hours. After the reaction was completed, the mixture was cooled, washed, and dried to obtain a carbon microsphere-hydrotalcite composite material. The reaction mass ratio of carbon microspheres, nickel nitrate hexahydrate, ferric nitrate nonahydrate, urea, and ammonium fluoride was 0.09:0.22:0.1:0.35:0.08.

[0066] Step S3: Add ferrous sulfate heptahydrate and ferric nitrate nonahydrate to deionized water, stir thoroughly to obtain an iron salt solution; then add carbon microsphere-hydrotalcite composite material, deionized water, and the mixture to the iron salt solution, ultrasonically disperse evenly, add sodium hydroxide to adjust the pH to 10.2, and react in a water bath at 85℃ for 30 minutes. After the reaction is complete, cool, wash, and dry to obtain the composite magnetic material; the reaction mass ratio of ferrous sulfate heptahydrate, ferric nitrate nonahydrate, and carbon microsphere-hydrotalcite composite material is 0.07:0.17:0.025.

[0067] Step S4: Mix 25g of composite magnetic material, 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol to obtain a composite magnetic adhesive.

[0068] The aluminum-magnesium alloy raw material is die-cast to obtain the shielding shell; composite magnetic adhesive is applied to the fixed position of the shielding cover, and after curing at 120℃ for 40 minutes and packaging, the finished product is obtained.

[0069] Comparative Example 3: The composite magnetic adhesive, silver-copper conductive composite adhesive, and silver-conductive composite adhesive were removed, but some of the adhesive preparation steps were retained; the rest were the same as in Example 1, and the specific steps are as follows: Step S1: 60g of vinyl polysiloxane, 10g of hydrogen-containing polysiloxane, 0.03g of chloroplatinic acid, and 0.03g of methylpentynol were mixed to obtain the adhesive;

[0070] Step S2: The aluminum-magnesium alloy raw material is die-cast to obtain the shielding shell; adhesive is applied to the fixed position of the shielding cover, and after curing at 120℃ for 40 minutes, it is packaged to obtain the finished product.

[0071] Testing and experimentation:

[0072] Electromagnetic shielding performance test: The adhesive prepared according to this invention was added sequentially to the mold (following the corresponding dispensing order of the examples / comparative examples), and after vulcanization, a circular sample with a diameter of 12 mm and a thickness of 2 mm was obtained. The electromagnetic shielding performance of the sample was tested using a vector network analyzer at a test frequency of 12 GHz. The test data were substituted into the formulas to calculate the electromagnetic absorption shielding effectiveness SE. A Electromagnetic reflection shielding effectiveness (SE) R The overall electromagnetic shielding effectiveness (SE) of the material T The results are shown in the table below:

[0073]

[0074] Conclusion: In Examples 1-3, the dosage remained unchanged, with only some reaction parameters modified. Experimental data showed no significant fluctuations in the performance of the samples.

[0075] Comparative Example 1: The silver-loaded conductive composite adhesive was removed, and the rest was the same as in Example 1. The experimental data showed that, compared with Example 1, the electromagnetic absorption shielding effectiveness decreased to 40.5 dB and the electromagnetic reflection shielding effectiveness decreased to 28.3 dB. The reason for this is that the silver-loaded conductive composite adhesive, based on the porous conductive composite material, introduced highly conductive metallic silver through a chemical reduction method, which further enhanced the conductivity of the material, thereby effectively increasing the chances of electromagnetic waves being scattered and absorbed inside the material. Therefore, removing it reduced both the electromagnetic absorption shielding effectiveness and the electromagnetic reflection shielding effectiveness.

[0076] Comparative Example 2: The silver-copper conductive composite adhesive and the silver-loaded conductive composite adhesive were removed, while the rest remained the same as in Example 1. Experimental data showed that, compared to Example 1, the electromagnetic absorption shielding effectiveness decreased to 38.5 dB, and the electromagnetic reflection shielding effectiveness decreased to 23.7 dB. The reason for this is that, based on Comparative Example 1, Comparative Example 2 removed the silver-copper conductive composite adhesive. The silver-copper conductive composite adhesive, based on a porous conductive composite material, simultaneously introduced highly conductive metallic silver and copper using a reduction method, thus possessing superior conductivity. This effectively increases the scattering and absorption opportunities of electromagnetic waves within the material. Therefore, removing it reduces both the electromagnetic absorption shielding effectiveness and the electromagnetic reflection shielding effectiveness.

[0077] Comparative Example 3: The composite magnetic adhesive, silver-copper conductive composite adhesive, and silver conductive composite adhesive were removed, while the rest remained the same as in Example 1. Experimental data showed that compared to Example 1, the electromagnetic absorption shielding effectiveness decreased to 26.2 dB, and the electromagnetic reflection shielding effectiveness decreased to 30.1 dB. The reason for this is that, based on Comparative Example 2, Comparative Example 3 removed the composite magnetic adhesive. The composite magnetic adhesive included strongly magnetic materials such as iron(III) oxide, strongly magnetic materials such as hydrotalcite, and conductive carbon microspheres, thus forming a highly efficient electromagnetic shielding system. Therefore, removing it reduced both the electromagnetic absorption and electromagnetic reflection shielding effectiveness.

[0078] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process method article or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process method article or apparatus.

[0079] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a shielding cover based on silicone rubber conductive adhesive, characterized in that: Includes the following steps: Aluminum-magnesium alloy raw materials are die-cast to obtain a shielding shell; composite magnetic adhesive, silver-copper conductive composite adhesive, and silver conductive composite adhesive are sequentially applied to the fixed position of the shielding cover, and after curing at 100-120℃ for 30-40 minutes and packaging, the finished product is obtained. The preparation process of the silver-copper conductive composite material is as follows: Step S1: Add polymethyl methacrylate powder to deionized water to obtain a polymethyl methacrylate solution; then add Ti3C2T X MXene powder was added to a polymethyl methacrylate solution and stirred thoroughly for 25-30 minutes. After stirring, the mixture was centrifuged to obtain a composite material. The composite material and graphene oxide were then added to deionized water and stirred thoroughly under argon atmosphere for 3-4 hours. After freeze-drying, a conductive composite material was obtained. The conductive composite material was then heat-treated under argon atmosphere at 440-450℃ for 1.2-1.5 hours to obtain a porous conductive composite material. Step S2: Add silver nitrate to deionized water to obtain silver nitrate solution; then add porous conductive composite material, ultrasonically disperse for 20-30 min, then add ethylene glycol, continue ultrasonic dispersion for 15-20 min, after uniform dispersion, react in a water bath at 35-40℃ for 15-20 h, after the reaction is completed, cool, centrifuge, wash and dry to obtain silver-loaded conductive composite material. Step S3: Add polyvinyl alcohol to deionized water to obtain a polyvinyl alcohol solution; add silver nitrate to deionized water to obtain a silver nitrate solution; Copper nitrate trihydrate was added to deionized water to obtain a copper nitrate solution; Silver nitrate solution and copper nitrate solution were mixed and stirred evenly. Then, porous conductive composite material was added and ultrasonically dispersed for 20-30 minutes. Polyvinyl alcohol solution was added and ultrasonically dispersed for another 15-20 minutes. After being evenly dispersed, the mixture was reacted in a water bath at 80-90℃ for 1.0-1.5 hours. After the reaction was completed, the mixture was cooled, centrifuged, washed, and dried to obtain silver-copper conductive composite material. The preparation process of composite magnetic materials is as follows: Step 1: Add xylose to deionized water to obtain a 0.45-0.50 mol / L xylose solution; The xylose solution was heat-treated at 180-200℃ for 11-13 hours. After the reaction was completed, the solution was cooled, filtered, washed, and dried to obtain carbon microspheres. Step 2: Add carbon microspheres to deionized water and add sodium hydroxide to adjust the pH to 11.0-11.2 to obtain a carbon microsphere solution; Nickel nitrate hexahydrate and ferric nitrate nonahydrate were added to deionized water to obtain a salt solution. The salt solution was added dropwise to the carbon microsphere solution. After the addition was complete, urea and ammonium fluoride were added. After ultrasonic dispersion, the mixture was reacted at 110-120℃ for 11-13 hours. After the reaction was completed, the mixture was cooled, washed, and dried to obtain the carbon microsphere-hydrotalcite composite material. Step 3: Add ferrous sulfate heptahydrate and ferric nitrate nonahydrate to deionized water and stir thoroughly to obtain an iron salt solution; then add carbon microsphere-hydrotalcite composite material, deionized water, and the iron salt solution, disperse evenly by ultrasonication, add sodium hydroxide to adjust the pH to 10.0-10.2, and react in a water bath at 80-85℃ for 20-30 minutes. After the reaction is completed, cool, wash, and dry to obtain the composite magnetic material.

2. The method for preparing a shielding cover based on silicone rubber conductive adhesive according to claim 1, characterized in that: By weight, 20-25 parts of composite magnetic material, 50-60 parts of vinyl polysiloxane, 8-10 parts of hydrogen-containing polysiloxane, 0.02-0.03 parts of chloroplatinic acid, and 0.02-0.03 parts of methylpentynol are mixed to obtain a composite magnetic adhesive; 20-25 parts of silver-copper conductive composite material, 50-60 parts of vinyl polysiloxane, 8-10 parts of hydrogen-containing polysiloxane, 0.02-0.03 parts of chloroplatinic acid, and 0.02-0.03 parts of methylpentynol are mixed to obtain a silver-copper conductive composite adhesive; 20-25 parts of silver-conductive composite material, 50-60 parts of vinyl polysiloxane, 8-10 parts of hydrogen-containing polysiloxane, 0.02-0.03 parts of chloroplatinic acid, and 0.02-0.03 parts of methylpentynol are mixed to obtain a silver-conductive composite adhesive.

3. The method for preparing a shielding cover based on silicone rubber conductive adhesive according to claim 1, characterized in that: In step S1, polymethyl methacrylate powder and Ti3C2T X The mass ratio of MXene powder to graphene oxide is (6-7):1:(4-5).

4. The method for preparing a shielding cover based on silicone rubber conductive adhesive according to claim 1, characterized in that: In step S2, when preparing the silver-loaded conductive composite material, the mass-volume ratio of silver nitrate, porous conductive composite material, and ethylene glycol is (0.35-0.40) g: 2.5 g: 20 mL.

5. The method for preparing a shielding cover based on silicone rubber conductive adhesive according to claim 1, characterized in that: In step S3, the reaction mass ratio of silver nitrate, copper nitrate trihydrate, porous conductive composite material, and polyvinyl alcohol is 0.15:(0.075-0.078):1.8:7.

5.

6. The method for preparing a shielding cover based on silicone rubber conductive adhesive according to claim 1, characterized in that: In step 2, the reaction mass ratio of carbon microspheres, nickel nitrate hexahydrate, ferric nitrate nonahydrate, urea, and ammonium fluoride is (0.08-0.1):0.22:0.1:0.35:0.

08.

7. The method for preparing a shielding cover based on silicone rubber conductive adhesive according to claim 1, characterized in that: In step 3, the reaction mass ratio of ferrous sulfate heptahydrate, ferric nitrate nonahydrate, and carbon microsphere-hydrotalcite composite material is 0.07:0.17:(0.02-0.03).

8. A shielding cover based on silicone rubber conductive adhesive, characterized in that, Prepared by the preparation method according to any one of claims 1-7.

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