Corrosion-resistant electromagnetic shielding material and preparation method thereof

Abstract

The embodiment of the invention provides a corrosion-resistant electromagnetic shielding material and a preparation method thereof, the corrosion-resistant electromagnetic shielding material is of a layered structure, and the corrosion-resistant electromagnetic shielding material sequentially comprises a conductive layer, an epoxy wave-absorbing layer and a first corrosion-resistant layer. The first corrosion-resistant layer comprises polyphenylene sulfide resin, epoxy fluorosilane modified graphene, polyether-ether-ketone resin and a dispersing agent. According to the corrosion-resistant electromagnetic shielding material provided by the invention, the polyphenylene sulfide resin is adopted as a matrix and has excellent corrosion resistance, the polyether-ether-ketone resin can improve and relieve the brittleness of the polyphenylene sulfide resin, and meanwhile, the epoxy-fluorosilane modified graphene can construct a continuous conductive network to assist in improving the electromagnetic shielding effectiveness; the graphene sheet layer can form a physical barrier network in a polyphenylene sulfide matrix, corrosion medium permeation is blocked, the corrosion resistance is further improved, a covalent bond can be formed between the epoxy group and the epoxy wave-absorbing layer, the interlayer binding force is improved, and the service life of equipment is prolonged.

Description

Corrosion-resistant electromagnetic shielding materials and their preparation methods Technical Field

[0001] This application relates to the field of electromagnetic shielding technology, specifically to a corrosion-resistant electromagnetic shielding material and its preparation method. Background Technology

[0002] As electronic technology advances towards higher frequencies, higher power, and miniaturization, electromagnetic radiation issues are becoming increasingly prominent, easily interfering with the normal operation of electronic equipment. Current electromagnetic shielding materials primarily achieve their shielding function by reflecting or absorbing electromagnetic waves. When electromagnetic waves are absorbed, they are converted into heat energy. However, the corrosion resistance of current electromagnetic shielding materials still has significant limitations. Summary of the Invention

[0003] To address at least one of the above-mentioned technical problems, embodiments of this application provide a corrosion-resistant electromagnetic shielding material.

[0004] In addition, this application also provides a method for preparing a corrosion-resistant electromagnetic shielding material.

[0005] This application provides a corrosion-resistant electromagnetic shielding material for electromagnetic shielding of electronic devices. The corrosion-resistant electromagnetic shielding material has a layered structure, comprising, in sequence, a conductive layer, an epoxy absorbing layer, and a first corrosion-resistant layer. The first corrosion-resistant layer, by weight, comprises at least 80-100 parts of polyphenylene sulfide resin, 10-20 parts of epoxy fluorosilane-modified graphene, 20-40 parts of polyetheretherketone resin, and 3-5 parts of dispersant.

[0006] In some embodiments of this application, the preparation method of the epoxy fluorosilane-modified graphene includes adding graphene oxide to anhydrous ethanol, ultrasonically dispersing for 30 to 40 minutes, adjusting the pH to 4-5, stirring for 10 to 15 minutes, adding a first silane coupling agent, stirring at 50 to 60 °C for 4 to 5 hours, centrifuging, and washing to obtain an intermediate. The intermediate and a second silane coupling agent are then added to anhydrous ethanol, the pH is adjusted to 8-9, and the mixture is stirred at 70 to 80 °C for 5 to 7 hours. The mixture is then centrifuged, washed, and dried to obtain the epoxy fluorosilane-modified graphene.

[0007] In some embodiments of this application, the mass ratio of the first silane coupling agent to the second silane coupling agent is 1:(1.5-2.5), and the mass ratio of the graphene oxide to the first silane coupling agent is 1:(3-4).

[0008] In some embodiments of this application, the first silane coupling agent is a fluorosilane coupling agent, and the first silane coupling agent includes any one of FAS-13 and FAS-17.

[0009] In some embodiments of this application, the second silane coupling agent is an epoxy silane coupling agent, and the second silane coupling agent includes any one of KH-560, Z-6040, and KH-561.

[0010] In some embodiments of this application, the dispersant is a mixture of a polyether-type dispersant and a high molecular weight block copolymer dispersant, wherein the mass ratio of the polyether-type dispersant to the high molecular weight block copolymer dispersant is 3:2.

[0011] In some embodiments of this application, the electromagnetic shielding material further includes a second corrosion-resistant layer, which is disposed on a surface of the first corrosion-resistant layer away from the epoxy absorbing layer. The second corrosion-resistant layer, by weight, includes 65-85 parts of waterborne fluorocarbon resin, 2-5 parts of modified titanium dioxide, 0.1-0.2 parts of BYK-190, and 0.5-0.8 parts of trifluoropropyltrimethoxysilane.

[0012] In some embodiments of this application, the modified titanium dioxide is fluorosilane-modified rutile titanium dioxide, and the particle size of the titanium dioxide is 20 nm to 30 nm.

[0013] In some embodiments of this application, the preparation method of the second corrosion-resistant layer includes mixing an aqueous fluorocarbon resin dispersion, modified titanium dioxide, BYK-190 and trifluoropropyltrimethoxysilane, adding propylene glycol methyl ether and deionized water, stirring at high speed for 10 min, ultrasonically dispersing for 15 min, filtering through a 0.2 μm to 0.3 μm filter membrane to obtain inkjet ink, spraying the inkjet ink onto the surface of the first corrosion-resistant layer using an inkjet printing process, and drying to obtain the second corrosion-resistant layer.

[0014] This application also provides a method for preparing the aforementioned corrosion-resistant electromagnetic shielding material, comprising mixing polyphenylene sulfide, polyetheretherketone, and epoxy fluorosilane-modified graphene, extruding and granulating, and molding to obtain a first corrosion-resistant layer. The material is then hot-pressed in the order of a conductive layer, an epoxy absorbing layer, and the first corrosion-resistant layer to obtain the corrosion-resistant electromagnetic shielding material.

[0015] Compared to existing technologies, the corrosion-resistant electromagnetic shielding material provided in this application features a layered structure. The first corrosion-resistant layer comprises polyphenylene sulfide resin, epoxy-fluorosilane-modified graphene, and polyetheretherketone resin, using polyphenylene sulfide resin as the matrix, which exhibits excellent corrosion resistance. The polyetheretherketone resin improves and alleviates the brittleness of polyphenylene sulfide resin. Simultaneously, the epoxy-fluorosilane-modified graphene constructs a continuous conductive network, further enhancing electromagnetic shielding effectiveness. The graphene sheets form a physical barrier network within the polyphenylene sulfide matrix, preventing the penetration of corrosive media and further improving corrosion resistance. Furthermore, the fluorosilane reduces the agglomeration of graphene in the blend, and the epoxy groups form covalent bonds with the epoxy absorbing layer, increasing interlayer bonding and extending equipment lifespan. Detailed Implementation

[0016] 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.

[0017] It should be noted that when a component is considered to be "connected" to another component, it can be directly connected to the other component or may also have a component that is centrally located. When a component is considered to be "located" on another component, it can be directly located on the other component or may also have a component that is centrally located.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0019] In practical applications of electromagnetic shielding materials, metal-based shielding materials undergo chemical corrosion under humid, salt spray, or acidic / alkaline environments. This leads to the formation of oxide layers, pitting, or peeling on the material surface, compromising the structural integrity and uniformity of the shielding layer. The corrosion process reduces the material's reflection efficiency and absorption capacity of electromagnetic waves, thus affecting the stability of electromagnetic shielding effectiveness and the long-term reliability of the material in electronic equipment. This degradation is particularly pronounced under high-frequency, high-power operating conditions. For example, in marine navigation system electronic equipment, continuous exposure to high salt spray and high humidity causes chloride corrosion products to form on the surface of the metal-based shielding layer. This weakens the electromagnetic shielding capability in localized areas, allowing external radio frequency interference signals to penetrate the shielding layer, leading to internal circuit signal distortion and system malfunctions, resulting in frequent equipment malfunctions. If these corrosion problems are not addressed, the performance of electromagnetic shielding materials will continue to degrade, leading to decreased reliability of electronic equipment under harsh conditions, increased risk of system failure, and potential safety hazards in critical infrastructure applications. This limits the applicability of electromagnetic shielding technology in a wide range of environmental conditions.

[0020] In related technologies, CN120091551A discloses a flexible electromagnetic shielding material and its preparation method. The electromagnetic shielding material sequentially comprises a first conductive layer, a composite absorbing layer, and a second conductive layer. Both the first and second conductive layers comprise thermoplastic resin and conductive materials. The composite absorbing layer comprises a mixture of epoxy resin, filler, and absorbing agent. By setting the electromagnetic shielding material into a layered structure, when electromagnetic waves contact the first conductive layer, an induced current is generated on the surface of the first conductive layer. The electromagnetic waves are reflected by its high conductivity. However, unreflected electromagnetic waves may also penetrate into the composite absorbing layer. The absorbing agent undergoes polarization under the action of electromagnetic waves, further absorbing them. When electromagnetic waves are not completely absorbed in the composite absorbing layer, the second conductive layer further reflects the electromagnetic waves, which are then absorbed again by the composite absorbing layer.

[0021] However, in practical applications, the inventors found that the conductive layer has low corrosion resistance and weak interlayer bonding on the outer conductive layer, making it prone to detachment in some special application scenarios, such as high salt spray environments, which affects the performance of electromagnetic shielding.

[0022] Therefore, this application provides a corrosion-resistant electromagnetic shielding material for electromagnetic shielding of electronic devices. The corrosion-resistant electromagnetic shielding material has a layered structure, comprising, in sequence, a conductive layer, a wave-absorbing layer, and a first corrosion-resistant layer.

[0023] In some embodiments, the conductive layer is mainly composed of a blend of thermally applied polyurethane elastomer and carbon fiber, wherein the mass ratio of carbon fiber to thermally applied polyurethane elastomer is 7:2. The conductive layer is prepared by mixing carbon fiber and thermoplastic polyurethane at a mass ratio of 7:2, drying, and then molding to obtain the conductive layer.

[0024] In some embodiments, the epoxy microwave absorbing layer comprises, by weight, the following components: 80-110 parts epoxy resin, 20-30 parts filler, 5-10 parts rare earth-based metal-organic framework, 1-2 parts first dispersant, 0.1-0.8 parts tetramethylammonium bromide and 80-90 parts methylhexahydrophthalic anhydride.

[0025] In some embodiments, the rare earth elements in the rare earth-based metal-organic framework are yttrium and gadolinium. The hierarchical porous structure of yttrium and gadolinium can increase the multiple reflection paths of electromagnetic waves. Combined with the interlayer dielectric polarization effect of lamellar boron nitride and hollow silicon microparticles, broadband electromagnetic wave absorption is achieved. The 4f electron transition of gadolinium can also enhance magnetic loss. The electronic configuration of yttrium allows it to form strong coordination bonds with organic ligands. The conjugated π electron system of the MOF framework enhances dielectric polarization, resulting in significant dielectric loss for high-frequency electromagnetic waves. At the same time, gadolinium has a high spin magnetic moment, which generates strong eddy current loss and natural resonance in alternating electromagnetic fields, effectively absorbing low-frequency interference. The combined use of yttrium and gadolinium can balance the ratio of dielectric loss and magnetic loss, and significantly improves adaptability, especially in complex electromagnetic environments. The molar ratio of yttrium to gadolinium is 2:3. When the molar ratio is 2:3, the lattice constant of the MOF matches the ligand size best, the crystal defect density is reduced, and the absorption performance is avoided due to lattice stress. The incorporation of yttrium suppresses the magnetic domain aggregation of gadolinium ions, prevents impedance mismatch caused by excessive magnetic loss in the epoxy absorbing layer, and improves the electromagnetic wave incident efficiency.

[0026] In some embodiments, the preparation method of the rare earth-based metal-organic framework includes the following steps: 2,5-dihydroxyterephthalic acid, yttrium nitrate hexahydrate, and gadolinium nitrate hexahydrate are weighed and placed in a reaction vessel, dissolved in N,N-dimethylformamide solution, and ultrasonically dispersed at room temperature for 50 to 60 minutes. The mixture is then transferred to a reaction vessel and reacted at 120 to 150 °C for 12 to 24 hours to obtain a mixed solution. Ethanol is added to the mixed solution, and the mixture is centrifuged at 10,000 to 12,000 r / min for 5 to 8 minutes to precipitate the product. The product is separated by centrifugation, and the precipitate is repeatedly washed with N,N-dimethylformamide solution and anhydrous ethanol solution until the supernatant is colorless. The product is filtered and vacuum dried at 65 to 75 °C for 12 to 24 hours to obtain the rare earth-based metal-organic framework. The mass ratio of the polydentate ligand 2,5-dihydroxyterephthalic acid to yttrium nitrate hexahydrate and gadolinium nitrate hexahydrate is 13:4. The use of the polydentate ligand 2,5-dihydroxyterephthalic acid results in high structural stability and a large specific surface area for multi-metal synthesized MOFs. Gadolinium provides magnetic loss, and yttrium provides dielectric loss, synergistically covering a wider frequency band.

[0027] In some embodiments, the filler is hollow silica powder and flake boron nitride. In some embodiments, the mass ratio of hollow silica powder to flake boron nitride is 1:3. By using a combination of hollow silica powder and flake boron nitride, the hollow structure of the hollow silica powder can reduce stress concentration in the resin matrix, and the blending of flake boron nitride and hollow silica powder can synergistically resist corrosion and rapidly dissipate heat.

[0028] In some embodiments, the first dispersant is POSS glycidyl etheroxypropylcyclotetrasiloxane, with a viscosity of 4500 cps to 4800 cps, a density of 125 g / ml to 130 g / ml, a molecular weight of 133788, and an epoxy equivalent of 167. It is an organic-inorganic hybrid cage-like polysilsesquioxane with a molecular size of 15 nm, used as a highly efficient dispersant for nanomaterials to enhance their dispersibility. It was purchased from Xi'an Ruixi Biotechnology Co., Ltd.

[0029] In some embodiments, the epoxy resin is a bisphenol A epoxy resin.

[0030] The first corrosion-resistant layer, by weight, comprises at least 80-100 parts of polyphenylene sulfide resin, 10-20 parts of epoxy fluorosilane modified graphene, 20-40 parts of polyether ether ketone resin, and 3-5 parts of a second dispersant.

[0031] In some embodiments, the polyphenylene sulfide resin is a linear polyphenylene sulfide resin, which has excellent high temperature resistance and excellent corrosion resistance. It can withstand complex environments such as strong acids, strong alkalis, and salt spray. As the matrix of the first corrosion-resistant layer, it can effectively block the corrosive medium from penetrating into the inner layer and protect the conductive layer and the epoxy absorbing layer.

[0032] In some embodiments, the preparation method of the epoxy fluorosilane modified graphene specifically includes the following steps: S101, adding graphene oxide to anhydrous ethanol, ultrasonically dispersing at 300 W for 30 to 40 minutes, adjusting the pH to 4-5 with acetic acid, stirring for 10 to 15 minutes, adding a first silane coupling agent, stirring at 50 to 60 °C for 4 to 5 hours, centrifuging and washing to obtain an intermediate.

[0033] In some embodiments, the first silane coupling agent is a fluorosilane coupling agent, including any one of FAS-13 and FAS-17. By selecting a fluorosilane with a medium chain length (C6-C8), sufficient steric hindrance can be provided to inhibit graphene aggregation without over-coating the surface, thus ensuring the grafting sites and reactivity of subsequent epoxy silanes.

[0034] S102. Add the intermediate and the second silane coupling agent to anhydrous ethanol, adjust the pH to 8-9, mix and stir at 70 ℃ to 80 ℃ for 5 h to 7 h, centrifuge, wash and dry to obtain modified graphene.

[0035] In some embodiments, the second silane coupling agent is an epoxy silane coupling agent, and the second silane coupling agent includes any one of KH-560, Z-6040, and KH-561.

[0036] By employing a step-by-step modification process using fluorosilane followed by epoxy silane, the dispersion and corrosion resistance of graphene in a linear polyphenylene sulfide resin matrix can be improved. Fluorosilane grafts are applied to the active sites of graphene to form a superhydrophobic layer, further enhancing the corrosion resistance of the first corrosion-resistant layer. Simultaneously, the modified graphene, after uniform dispersion, forms a continuous labyrinth structure, effectively blocking the diffusion of small-molecule corrosive media. Furthermore, the subsequently grafted epoxy groups, during the hot-pressing process of preparing the corrosion-resistant electromagnetic shielding material, contribute to the interfacial bonding between the first corrosion-resistant layer and the epoxy absorbing layer, thereby improving the interlayer bonding strength of the corrosion-resistant electromagnetic shielding material.

[0037] In some embodiments, the mass ratio of the first silane coupling agent to the second silane coupling agent is 1:(1.5-2.5), and the mass ratio of the graphene oxide to the first silane coupling agent is 1:(3-4).

[0038] For example, the mass ratio of the first silane coupling agent and the second silane coupling agent can be 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, or any value within the range of any two of the above ratios. Preferably, the mass ratio of the first silane coupling agent and the second silane coupling agent is 1:1.8.

[0039] In some embodiments, the second dispersant is a mixture of a polyether-type dispersant and a high molecular weight block copolymer dispersant, wherein the mass ratio of the polyether-type dispersant to the high molecular weight block copolymer dispersant is 3:2.

[0040] In some embodiments, the polyether dispersant used is BYK-348, purchased from BYK Chemicals (Germany), and the high molecular weight block copolymer is SEBS-g-MAH. The combination of these two components reduces the melt viscosity of polyphenylene sulfide and polyether ether ketone resins, further improving the processing flowability of modified graphene in polyphenylene sulfide and polyether ether ketone resin matrices. The anhydride groups of the high molecular weight block copolymer can bond with some of the epoxy groups on the surface of the modified graphene, anchoring the modified graphene sheets and further improving corrosion resistance.

[0041] In some embodiments, the first corrosion-resistant layer further includes 1 to 3 parts of antioxidant.

[0042] In some embodiments, the electromagnetic shielding material further includes a second corrosion-resistant layer disposed on a surface of the first corrosion-resistant layer away from the microwave absorbing layer. The second corrosion-resistant layer, by weight, includes 65-85 parts of waterborne fluorocarbon resin, 2-5 parts of modified titanium dioxide, 0.1-0.2 parts of BYK-190, and 0.5-0.8 parts of trifluoropropyltrimethoxysilane.

[0043] In some embodiments, the modified titanium dioxide is fluorosilane-modified rutile titanium dioxide, and the particle size of the titanium dioxide is 20 nm to 30 nm. Modified titanium dioxide can fill the microscopic voids present after the aqueous fluorocarbon resin film is formed, eliminating the penetration channels of corrosive media and further improving corrosion resistance. Fluorosilane modification not only imparts hydrophobicity to the titanium dioxide but also enhances its interfacial compatibility with the aqueous fluorocarbon resin, avoiding film defects caused by the agglomeration of unmodified titanium dioxide. The silicon-oxygen bonds on the surface of the titanium dioxide can undergo a weak cross-linking reaction with the active groups of the aqueous fluorocarbon resin, strengthening the interfacial bonding force between the resin and the titanium dioxide, while simultaneously improving the adhesion strength between the second corrosion-resistant layer and the first corrosion-resistant layer, preventing film detachment and failure. Rutile titanium dioxide is chemically stable, resists acid and alkali corrosion, and can also absorb ultraviolet light, reducing the degradation effect of ultraviolet light on fluorocarbon resin. Waterborne fluorocarbon resin itself has excellent chemical corrosion resistance and weather resistance. When combined with the anti-aging properties of titanium dioxide, it can slow down the powdering and cracking of the film layer in harsh environments and ensure the long-term stability of corrosion resistance.

[0044] In some embodiments, the preparation method of fluorosilane-modified rutile titanium dioxide includes adding titanium dioxide to anhydrous ethanol and ultrasonically dispersing it for 20 min to obtain a titanium dioxide dispersion. Trifluoropropyltrimethoxysilane, anhydrous ethanol, and deionized water are mixed, the pH is adjusted to 4-5, the titanium dioxide dispersion is added, and the mixture is stirred for 2 h. The mixture is then centrifuged, washed, and dried to obtain modified titanium dioxide. The mass ratio of titanium dioxide to trifluoropropyltrimethoxysilane is 1:0.05.

[0045] In some embodiments, the preparation method of the second corrosion-resistant layer includes mixing an aqueous fluorocarbon resin dispersion, modified titanium dioxide, BYK-190, and trifluoropropyltrimethoxysilane, adding propylene glycol methyl ether and deionized water, stirring at high speed for 10 min, ultrasonically dispersing for 15 min, filtering through a 0.2 μm to 0.3 μm filter membrane to obtain inkjet ink, and spraying the inkjet ink onto the surface of the first corrosion-resistant layer using an inkjet printing process, and drying to obtain the second corrosion-resistant layer. Adding titanium dioxide can construct a dense hydrophobic barrier network, further improving corrosion resistance. Furthermore, the colors of the conductive layer and the corrosion-resistant layer can be better distinguished. Compared to existing technologies, the corrosion-resistant electromagnetic shielding material provided in this application, by setting the material as a layered structure, wherein the first corrosion-resistant layer is polyphenylene sulfide resin, epoxy fluorosilane modified graphene, and polyetheretherketone resin, using polyphenylene sulfide resin as the matrix, has excellent corrosion resistance. Polyetheretherketone (PEEK) resin can improve and alleviate the brittleness of polyphenylene sulfide (PPS) resin. Meanwhile, epoxy-fluorosilane modified graphene can construct a continuous conductive network, which helps to improve electromagnetic shielding effectiveness. Graphene sheets can form a physical barrier network in the PPS matrix to block the penetration of corrosive media and further improve corrosion resistance. At the same time, fluorosilane can reduce the agglomeration of graphene in the blend, and epoxy groups can form covalent bonds with the epoxy absorbing layer, which can improve the interlayer bonding force and extend the service life of the equipment.

[0046] This application also provides a method for preparing a corrosion-resistant electromagnetic shielding material, comprising the following steps: S1, mixing polyphenylene sulfide, polyether ether ketone, dispersant and epoxy fluorosilane modified graphene, extruding and granulating, and molding to obtain a first corrosion-resistant layer.

[0047] In some embodiments, the molding temperature is 350 °C to 360 °C.

[0048] S2. The conductive layer, the wave-absorbing layer and the first corrosion-resistant layer are hot-pressed in sequence to obtain a corrosion-resistant electromagnetic shielding material.

[0049] In some embodiments, the hot-pressing temperature is 200 °C to 220 °C. The hot-pressing time is 15 min.

[0050] The aforementioned corrosion-resistant electromagnetic shielding material will be further illustrated below through specific embodiments.

[0051] (1) Preparation of conductive layer: carbon fiber and thermoplastic polyurethane are mixed at a mass ratio of 7:2, dried and then molded to obtain conductive layer.

[0052] (2) Preparation of epoxy microwave absorbing layer: Weigh 110 parts by weight of bisphenol A epoxy resin, 20 parts by weight of hollow silica powder and sheet boron nitride in a mass ratio of 1:3, and 10 parts by weight of rare earth-based metal-organic framework, and stir and mix for 1 h until uniformly mixed to obtain a premix. Add 2 parts by weight of dispersant POSS glycidyl etheroxypropylcyclotetrasiloxane to the premix, stir and disperse the premix and dispersant for 10 min, remove and degas under vacuum for 10 min to obtain the first mixture. Mix 0.7 parts by weight of tetramethylammonium bromide and 80 parts by weight of methylhexahydrophthalic anhydride for 15 min to obtain the second mixture. Shear and mix the first mixture and the second mixture at 50 °C for 15 min to obtain a blend solution, then dry under vacuum and mold to obtain the epoxy microwave absorbing layer.

[0053] Example 1, Step 1: Graphene oxide was added to anhydrous ethanol and ultrasonically dispersed at 300 W for 30 min. The pH was adjusted to 4 with acetic acid, and the mixture was stirred for 10 min. FAS-13 was added, and the mixture was stirred at 50 °C for 4 h. After centrifugation and washing, an intermediate was obtained. The intermediate and KH-560 were added to anhydrous ethanol, the pH was adjusted to 8, and the mixture was stirred at 80 °C for 5 h. After centrifugation, washing, and drying, modified graphene was obtained. The mass ratio of FAS-13 to KH-560 was 1:1.5, and the mass ratio of graphene oxide to FAS-13 was 1:3.

[0054] Step 2: Mix 80 parts polyphenylene sulfide, 20 parts polyetheretherketone, 3 parts dispersant, and 10 parts epoxy fluorosilane modified graphene, extrude and granulate, and then mold at 350 ℃ to obtain the first corrosion-resistant layer. The extrusion process parameters are set as follows: feeding section temperature 290 ℃, melting section temperature 355 ℃, shearing section temperature 350 ℃, and homogenization section temperature 345 ℃.

[0055] Step 3: Following the order of the conductive layer prepared in (1), the microwave absorbing layer prepared in (2), and the first corrosion-resistant layer, lay them layer by layer in a hot press mold and hot press them to form a corrosion-resistant electromagnetic shielding material. The hot pressing temperature is 200 ℃ and the hot pressing time is 15 min.

[0056] Example 2, Step 1: Graphene oxide was added to anhydrous ethanol and ultrasonically dispersed at 300 W for 30 min. The pH was adjusted to 4 with acetic acid, and the mixture was stirred for 10 min. FAS-17 was added, and the mixture was stirred at 50 °C for 4 h. After centrifugation and washing, an intermediate was obtained. The intermediate and KH-560 were added to anhydrous ethanol, the pH was adjusted to 8, and the mixture was stirred at 80 °C for 5 h. After centrifugation, washing, and drying, modified graphene was obtained. The mass ratio of FAS-13 to KH-560 was 1:1.8, and the mass ratio of graphene oxide to FAS-13 was 1:3.

[0057] Step 2: Mix 100 parts polyphenylene sulfide, 30 parts polyetheretherketone, 5 parts dispersant, and 20 parts epoxy fluorosilane modified graphene, extrude and granulate, and then mold at 350 ℃ to obtain the first corrosion-resistant layer. The extrusion process parameters are set as follows: feeding section temperature 290 ℃, melting section temperature 355 ℃, shearing section temperature 350 ℃, and homogenization section temperature 345 ℃.

[0058] Step 3: Following the order of the conductive layer prepared in (1), the microwave absorbing layer prepared in (2), and the first corrosion-resistant layer, lay them layer by layer in a hot press mold and hot press them to form a corrosion-resistant electromagnetic shielding material. The hot pressing temperature is 200 ℃ and the hot pressing time is 15 min.

[0059] Example 3, Step 1: Graphene oxide was added to anhydrous ethanol and ultrasonically dispersed at 300 W for 30 min. The pH was adjusted to 4 with acetic acid, and the mixture was stirred for 10 min. FAS-13 was added, and the mixture was stirred at 50 °C for 4 h. After centrifugation and washing, an intermediate was obtained. The intermediate and KH-560 were added to anhydrous ethanol, the pH was adjusted to 8, and the mixture was stirred at 80 °C for 5 h. After centrifugation, washing, and drying, modified graphene was obtained. The mass ratio of FAS-13 to KH-560 was 1:2.5, and the mass ratio of graphene oxide to FAS-13 was 1:3.

[0060] Step 2: Mix 90 parts polyphenylene sulfide, 40 parts polyetheretherketone, 4 parts dispersant, and 15 parts epoxy fluorosilane modified graphene, extrude and granulate, and then mold at 350 ℃ to obtain the first corrosion-resistant layer. The extrusion process parameters are set as follows: feeding section temperature 290 ℃, melting section temperature 355 ℃, shearing section temperature 350 ℃, and homogenization section temperature 345 ℃.

[0061] Step 3: Following the order of the conductive layer prepared in (1), the microwave absorbing layer prepared in (2), and the first corrosion-resistant layer, lay them layer by layer in a hot press mold and hot press them to form a corrosion-resistant electromagnetic shielding material. The hot pressing temperature is 200 ℃ and the hot pressing time is 15 min.

[0062] Example 4, Step 1: Graphene oxide was added to anhydrous ethanol and ultrasonically dispersed at 300 W for 30 min. The pH was adjusted to 4 with acetic acid, and the mixture was stirred for 10 min. FAS-17 was added, and the mixture was stirred at 50 °C for 4 h. After centrifugation and washing, an intermediate was obtained. The intermediate and KH-560 were added to anhydrous ethanol, the pH was adjusted to 8, and the mixture was stirred at 80 °C for 5 h. After centrifugation, washing, and drying, modified graphene was obtained. The mass ratio of FAS-13 to KH-560 was 1:1.8, and the mass ratio of graphene oxide to FAS-13 was 1:3.

[0063] Step 2: Mix 100 parts polyphenylene sulfide, 30 parts polyetheretherketone, 5 parts dispersant, and 20 parts epoxy fluorosilane modified graphene, extrude and granulate, and then mold at 350 ℃ to obtain the first corrosion-resistant layer. The extrusion process parameters are set as follows: feeding section temperature 290 ℃, melting section temperature 355 ℃, shearing section temperature 350 ℃, and homogenization section temperature 345 ℃.

[0064] Step 3: Mix 85 parts of aqueous fluorocarbon resin dispersion, 3 parts of modified titanium dioxide, 0.1 parts of BYK-190 and 0.8 parts of trifluoropropyltrimethoxysilane, add propylene glycol methyl ether and deionized water, stir at high speed for 10 min, ultrasonically disperse for 15 min, and filter through a 0.2 μm filter membrane to obtain inkjet ink. Coat the inkjet ink using an inkjet printer with the printhead temperature set at 40℃, the printing speed set at 45 mm / s, and the single-layer printing thickness at 0.3 μm. Print 3 layers on the surface of the first corrosion-resistant layer preform, dry at 60℃, and then cure at 150℃ for 30 min to obtain the first corrosion-resistant layer with the second corrosion-resistant layer.

[0065] Step 4: Following the order of the conductive layer prepared in (1), the microwave absorbing layer prepared in (2), and the first corrosion-resistant layer obtained in step 3, lay them layer by layer in a hot press mold and hot press to form a corrosion-resistant electromagnetic shielding material. The hot pressing temperature is 200 ℃ and the hot pressing time is 15 min.

[0066] The specific process of preparation of Comparative Example 1 is the same as that of Example 1. The difference is that the mass ratio of FAS-13 to KH-560 in step 1 is 1:1. The preparation methods of the other electromagnetic shielding materials are basically the same as those of Example 1, and will not be described in detail here.

[0067] The specific process of preparation of Comparative Example 2 is the same as that of Example 1. The difference is that in step 1, only FAS-13 is used to modify the graphene. The preparation methods of the other electromagnetic shielding materials are basically the same as those of Example 1, and will not be described in detail here.

[0068] The specific process of preparation of Comparative Example 3 is the same as that of Example 1. The difference is that in step 1, FAS-13 is replaced with long-chain fluorosilane, namely perfluorodecyltrimethoxysilane for modification. The preparation methods of the other electromagnetic shielding materials are basically the same as those of Example 1, and will not be described in detail here.

[0069] The specific process of preparation of Comparative Example 4 is the same as that of Example 1, except that in step 1, FAS-13 is replaced with trifluoropropyltrimethoxysilane modification. The preparation methods of the other electromagnetic shielding materials are basically the same as those of Example 1, and will not be described in detail here.

[0070] The specific process of preparation of Comparative Example 5 is the same as that of Example 1, except that polyetheretherketone resin was not used in step 2. The preparation methods of the other electromagnetic shielding materials are basically the same as those of Example 1, and will not be described in detail here.

[0071] The specific process of preparation of Comparative Example 6 is the same as that of Example 1, except that polyphenylene sulfide resin was not used in step 2, and the amount of polyether ether ketone resin was increased to 100 parts. The preparation methods of the other electromagnetic shielding materials are basically the same as those of Example 1, and will not be described in detail here.

[0072] The specific process of preparation of Comparative Example 7 is the same as that of Example 1. The difference is that graphene is not modified in step 1, and polyphenylene sulfide resin and polyether ether ketone resin are replaced with thermoplastic polyurethane in step 2. The preparation methods of the other electromagnetic shielding materials are basically the same as those of Example 1, and will not be described in detail here.

[0073] The corrosion-resistant electromagnetic shielding materials obtained in Examples 1-4 and Comparative Examples 1-7 were subjected to performance tests using the following methods, and the test results are shown in Table 1.

[0074] Table 1

[0075] As shown in Table 1, in Comparative Example 1, the mass ratio of FAS-13 to KH-560 was 1:1. The insufficient amount of coupling agent KH-560 resulted in a low grafting rate on the graphene surface, poor interfacial compatibility, and decreased interlayer adhesion and shielding effectiveness. Comparative Example 2 used only FAS-13 for modification, lacking the cross-linking effect of KH-560 on the epoxy-based siloxanes, leading to a decrease in the interfacial bonding between the first corrosion-resistant layer and the epoxy resin matrix. In Comparative Examples 3-4, fluorosilanes were replaced with either long-chain or short-chain fluorosilanes. Long-chain fluorosilanes easily masked the epoxy groups, affecting interlayer adhesion, while short-chain fluorosilanes lacked sufficient corrosion resistance; neither could achieve the modification effect of FAS-13 or FAS-17. In Comparative Examples 5-6, a single resin system (without polyphenylene sulfide or polyether ether ketone) was used, lacking the synergistic reinforcing effect of the two resins, resulting in decreased mechanical properties and corrosion resistance. In Comparative Example 7, the unmodified graphene was blended with thermoplastic polyurethane resin, resulting in severe graphene agglomeration, and the corrosion resistance and heat resistance of the polyurethane were far lower than those of the polyphenylene sulfide and polyether ether ketone blend system.

[0076] Therefore, the corrosion-resistant electromagnetic shielding material provided in this application, by setting the material into a layered structure, wherein the first corrosion-resistant layer is composed of polyphenylene sulfide resin, epoxy fluorosilane-modified graphene, and polyetheretherketone resin, using polyphenylene sulfide resin as the matrix, has excellent corrosion resistance. Polyetheretherketone resin can improve and alleviate the brittleness of polyphenylene sulfide resin. Simultaneously, epoxy-fluorosilane-modified graphene can construct a continuous conductive network, further enhancing electromagnetic shielding effectiveness. Graphene sheets can form a physical barrier network within the polyphenylene sulfide matrix, blocking the penetration of corrosive media and further improving corrosion resistance. At the same time, fluorosilane can reduce the agglomeration of graphene in the blend, and epoxy groups can form covalent bonds with the epoxy absorbing layer, improving interlayer bonding and extending equipment lifespan.

[0077] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit it. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the spirit and substance of the technical solutions of this application.

Claims

1. A corrosion-resistant electromagnetic shielding material for electromagnetic shielding of electronic equipment, characterized in that, The corrosion-resistant electromagnetic shielding material has a layered structure, comprising a conductive layer, an epoxy absorbing layer, and a first corrosion-resistant layer in sequence. The first corrosion-resistant layer, by weight, comprises at least 80-100 parts of polyphenylene sulfide resin, 10-20 parts of epoxy fluorosilane modified graphene, 20-40 parts of polyether ether ketone resin, and 3-5 parts of dispersant.

2. The corrosion-resistant electromagnetic shielding material according to claim 1, characterized in that, The method for preparing the modified graphene includes: adding graphene oxide to anhydrous ethanol, ultrasonically dispersing for 30 to 40 minutes, adjusting the pH to 4-5, stirring for 10 to 15 minutes, adding a first silane coupling agent, stirring at 50 to 60 °C for 4 to 5 hours, centrifuging and washing to obtain an intermediate; adding the intermediate and a second silane coupling agent to anhydrous ethanol, adjusting the pH to 8-9, mixing and stirring at 70 to 80 °C for 5 to 7 hours, centrifuging, washing and drying to obtain the modified graphene.

3. The corrosion-resistant electromagnetic shielding material according to claim 2, characterized in that, The mass ratio of the first silane coupling agent to the second silane coupling agent is 1:(1.5-2.5), and the mass ratio of the graphene oxide to the first silane coupling agent is 1:(3-4).

4. The corrosion-resistant electromagnetic shielding material according to claim 3, characterized in that, The first silane coupling agent is a fluorosilane coupling agent, and the first silane coupling agent includes any one of FAS-13 and FAS-17.

5. The corrosion-resistant electromagnetic shielding material according to claim 3, characterized in that, The second silane coupling agent is an epoxy silane coupling agent, and the second silane coupling agent includes any one of KH-560, Z-6040, and KH-561.

6. The corrosion-resistant electromagnetic shielding material according to claim 1, characterized in that, The dispersant is a mixture of a polyether-type dispersant and a high molecular weight block copolymer dispersant, wherein the mass ratio of the polyether-type dispersant to the high molecular weight block copolymer dispersant is 3:

2.

7. The corrosion-resistant electromagnetic shielding material according to claim 1, characterized in that, It also includes a second corrosion-resistant layer, which is disposed on the surface of the first corrosion-resistant layer away from the epoxy microwave absorbing layer. The second corrosion-resistant layer, by weight, includes 65 to 85 parts of waterborne fluorocarbon resin, 2 to 5 parts of modified titanium dioxide, 0.1 to 0.2 parts of BYK-190 and 0.5 to 0.8 parts of trifluoropropyltrimethoxysilane.

8. The corrosion-resistant electromagnetic shielding material according to claim 7, characterized in that, The modified titanium dioxide is fluorosilane-modified rutile titanium dioxide, and the particle size of the titanium dioxide is 20 nm to 30 nm.

9. The corrosion-resistant electromagnetic shielding material according to claim 7, characterized in that, The preparation method of the second corrosion-resistant layer includes: mixing an aqueous fluorocarbon resin dispersion, modified titanium dioxide, BYK-190 and trifluoropropyltrimethoxysilane, adding propylene glycol methyl ether and deionized water, stirring at high speed for 10 min, ultrasonically dispersing for 15 min, filtering through a 0.2 μm to 0.3 μm filter membrane to obtain inkjet ink, spraying the inkjet ink onto the surface of the first corrosion-resistant layer using an inkjet printing process, and drying to obtain the second corrosion-resistant layer.

10. A method for preparing a corrosion-resistant electromagnetic shielding material as described in any one of claims 1-9, characterized in that, include: A first corrosion-resistant layer is obtained by mixing polyphenylene sulfide, polyether ether ketone and epoxy fluorosilane modified graphene, extruding and granulating, and then molding. Corrosion-resistant electromagnetic shielding material is obtained by hot pressing the conductive layer, epoxy absorbing layer and first corrosion-resistant layer in sequence.

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