An electromagnetic shielding coating, its preparation method, and its application in camouflage awnings.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-24
- Publication Date
- 2026-08-14
AI Technical Summary
现有的电磁屏蔽涂层多采用水性树脂或亲水性聚合物作为基体，或者因导电填料分散不均导致涂层内部存在微孔
（1）本发明制备的电磁屏蔽涂层，按质量份数计，原料组分包括40~45质量份环氧树脂、5~10质量份改性聚二甲基硅氧烷、26.5~27.5质量份疏水填料、26.5~27.5质量份电磁屏蔽填料、5.09~5.27质量份樟脑磺酸；通过添加改性聚二甲基硅氧烷、疏水填料赋予涂层优异的疏水性；电磁屏蔽填料的引入可以赋予涂层良好的电磁屏蔽性能和红外隐身性能。
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Abstract
Description
Technical Field
[0001] This invention relates to electromagnetic shielding coatings, specifically to an electromagnetic shielding coating, its preparation method, and its application in camouflage awnings. Background Technology
[0002] With the rapid development of modern reconnaissance technology, detection methods have evolved from single visible light reconnaissance to a comprehensive multi-spectral and composite detection system encompassing radar, infrared, and laser. To survive in complex electromagnetic environments, camouflage equipment such as camouflage canopies and barriers must possess the dual capabilities to counter radar wave detection and infrared thermal imaging reconnaissance. Therefore, the development of composite coatings that combine electromagnetic shielding and infrared stealth functions has become a research hotspot in the field of camouflage materials.
[0003] However, in practical applications, achieving compatibility between electromagnetic shielding and infrared stealth presents an inherent physical contradiction. According to electromagnetic theory, efficient electromagnetic shielding typically relies on the high conductivity of materials to attenuate electromagnetic waves through reflection loss; while infrared stealth technology requires materials with low emissivity, i.e., high reflectivity in the infrared band. Although highly conductive materials simultaneously meet the requirements of high electromagnetic shielding and low infrared emissivity, existing technical solutions still face the following significant challenges when applied to camouflage coatings: First, camouflage tents are exposed to the elements for extended periods, requiring them to withstand harsh conditions such as rain and humidity. Existing electromagnetic shielding coatings often use water-based resins or hydrophilic polymers as the matrix, or suffer from micropores due to uneven dispersion of conductive fillers. When the coating absorbs water or becomes damp, it not only damages the conductive network and significantly reduces shielding effectiveness, but may also cause blistering and peeling. The lack of excellent waterproofing properties makes it difficult for existing coatings to guarantee long-term stability in all-weather environments.
[0004] Secondly, the substrate of camouflage awnings is usually made of high-strength synthetic fiber fabrics (such as polyester and nylon). These materials have low surface energy, strong chemical inertness, and smooth surfaces, making it difficult for coatings to wet and adhere. Existing rigid shielding coatings have poor flexibility after curing. When the camouflage awning is expanded, folded, or deformed by wind, the coating is prone to micro-cracks or even peeling off. This not only destroys the appearance of the camouflage but also cuts off the conductive path, causing the electromagnetic shielding function to fail.
[0005] Therefore, there is an urgent need to develop an electromagnetic shielding coating to solve the above problems. Summary of the Invention
[0006] The purpose of this invention is to provide an electromagnetic shielding coating, its preparation method, and its application in camouflage awnings, in order to solve the technical problems mentioned in the background section.
[0007] The technical solution to achieve the objective of this invention is: In a first aspect, the present invention provides an electromagnetic shielding coating, wherein, by mass parts, the raw material components include 40-45 parts by mass of epoxy resin, 5-10 parts by mass of modified polydimethylsiloxane, 26.5-27.5 parts by mass of hydrophobic filler, 26.5-27.5 parts by mass of electromagnetic shielding filler, and 5.09-5.27 parts by mass of camphor sulfonic acid.
[0008] Furthermore, the modified polydimethylsiloxane is obtained by hydrosilylation reaction of 4-vinylaniline and polymethylhydrosiloxane.
[0009] Furthermore, the hydrophobic filler includes modified silica.
[0010] Furthermore, the electromagnetic shielding filler is obtained by modifying MXene with o-vanillin Schiff base; the MXene includes Ti3C2T x MXene.
[0011] Furthermore, the o-vanillin Schiff base is obtained by reacting vanillin with o-phenylenediamine.
[0012] In a second aspect, the present invention provides a method for preparing an electromagnetic shielding coating as described in the first aspect, the preparation steps including: (1) Weighing and preparing materials; (2) Under nitrogen protection, the modified polydimethylsiloxane and electromagnetic shielding filler were added to 150-300 parts by weight of 1M hydrochloric acid solution and mixed. The mixture was ultrasonically dispersed for 20-40 minutes under ice bath conditions. Then, under ice bath conditions, hydrochloric acid solution containing 11-12 parts by weight of ammonium persulfate was added dropwise over 30 minutes. The mixture was then stirred for 2-4 hours and allowed to stand for at least 60 minutes. The precipitate was then washed with hydrochloric acid solution, anhydrous ethanol, and deionized water in sequence. After centrifugation until the supernatant was neutral, the precipitate was dried to obtain the first mixture. (3) After mixing and grinding the first mixture with camphor sulfonic acid for at least 30 minutes, add epoxy resin and continue mixing. Finally, add hydrophobic filler and stir for at least 30 minutes. After sonication for at least 10 minutes, add ethanol to adjust the viscosity of the coating measured by the four cups to 15~20s. Then, scrape it onto the substrate and dry it at room temperature for 3~5 hours. Place it in a drying oven at 78~82℃ for 10 hours to obtain an electromagnetic shielding coating.
[0013] Further, the preparation steps of the modified polydimethylsiloxane are as follows: Under nitrogen protection, 16-17 parts by weight of 4-vinylaniline, 0.004-0.006 parts by weight of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum (0), and 24-26 parts by weight of anhydrous toluene are mixed and stirred for 10-20 minutes. Then, the temperature is raised to 68-72°C, and a mixture of 24-26 parts by weight of anhydrous toluene containing 10 parts by weight of polymethylhydrosiloxane is added dropwise. The dropwise addition time is controlled at 90 minutes. Then, the mixture is heated to 100-110°C and reacted for 11-13 hours. After the reaction is completed, the mixture is rotary evaporated at 70°C to obtain the modified polydimethylsiloxane.
[0014] Furthermore, the preparation steps of the electromagnetic shielding filler are as follows: o-vanillin Schiff base is added to 10~20mg / mL MXene dispersion and stirred for 1~4h. The mass ratio of o-vanillin Schiff base to MXene is (0.75~1):5, and the electromagnetic shielding filler is obtained.
[0015] Further, the preparation steps of the o-vanillin Schiff base are as follows: 1.52 parts by mass of o-vanillin are directly dissolved in 32-40 parts by mass of anhydrous ethanol, refluxed for 30 min, and then an anhydrous ethanol solution containing 1,2-phenylenediamine is added dropwise and refluxed for another 50-70 min. The molar ratio of 1,2-phenylenediamine to o-vanillin is (1-1.2):1. After the reaction is completed, the mixture is filtered, recrystallized in anhydrous ethanol, and dried to obtain the o-vanillin Schiff base.
[0016] In a second aspect, the present invention provides an application of the electromagnetic shielding coating as described in the first aspect in a camouflage awning, wherein the thickness of the electromagnetic shielding coating in the camouflage awning is controlled at 20~40μm.
[0017] By adopting the above technical solution, the present invention has the following beneficial effects: (1) The electromagnetic shielding coating prepared by the present invention comprises, by mass parts, 40-45 parts epoxy resin, 5-10 parts modified polydimethylsiloxane, 26.5-27.5 parts hydrophobic filler, 26.5-27.5 parts electromagnetic shielding filler, and 5.09-5.27 parts camphor sulfonic acid; the addition of modified polydimethylsiloxane and hydrophobic filler imparts excellent hydrophobicity to the coating; the introduction of electromagnetic shielding filler can impart good electromagnetic shielding performance and infrared stealth performance to the coating.
[0018] (2) The modified polydimethylsiloxane of the present invention is obtained by hydrosilylation reaction of 4-vinylaniline and polymethylhydrosiloxane. The 4-vinylaniline group is chemically grafted onto the flexible polysiloxane molecular backbone, which effectively improves the problem of poor compatibility between traditional polydimethylsiloxane and epoxy resin matrix. The introduced 4-vinylaniline group enhances the dispersion uniformity of modified polysiloxane in epoxy resin and effectively suppresses the occurrence of macroscopic phase separation.
[0019] (3) The electromagnetic shielding filler of the present invention is obtained by modifying MXene with o-vanillin Schiff base; the MXene includes Ti3C2T x MXene, Ti3C2T x MXene not only possesses an excellent conductive network structure, enabling efficient electromagnetic wave reflection and absorption loss, but also exhibits extremely low infrared emissivity due to the high efficiency of Ti3C2T. x The inherent defects in the MXene structure make it highly susceptible to oxidation in water and oxygen environments, transforming it into titanium dioxide and causing a sharp decline in performance. The phenolic hydroxyl groups in the o-vanillin Schiff base can not only effectively scavenge reactive oxygen free radicals, but also form covalent bonds with titanium atoms on the MXene surface, thereby constructing a robust antioxidant protective layer, improving the environmental stability of MXene, and ensuring the stability of the coating's electromagnetic shielding and infrared stealth performance.
[0020] (4) In the preparation of the electromagnetic shielding coating of the present invention, the modified polydimethylsiloxane and the electromagnetic shielding filler are first mixed under acidic conditions with the introduction of ammonium persulfate; then, camphor sulfonic acid, epoxy resin, and hydrophobic filler are mixed and dispersed in sequence, and the coating viscosity is adjusted for scraping; wherein, the modified polydimethylsiloxane is obtained by hydrosilylation reaction of 4-vinylaniline and polymethylhydrosiloxane, and aniline is introduced into the side chain of the modified polydimethylsiloxane; the electromagnetic shielding filler is obtained by modifying MXene with o-vanillin Schiff base; o-vanillin Schiff base is obtained by mixing vanillin and o-phenylenediamine in a molar ratio of 1:(1~1.2) A segment of o-vanillin Schiff base containing an aniline structure was obtained. When the modified polydimethylsiloxane and the electromagnetic shielding filler were mixed under acidic conditions with the introduction of ammonium persulfate, the aniline on the side chain of the modified polydimethylsiloxane and the aniline on the surface of the electromagnetic shielding filler underwent a chemical oxidation polymerization reaction, and a polyaniline molecular chain cross-linking network was constructed in situ between the modified polydimethylsiloxane and the electromagnetic shielding filler. Subsequently, camphor sulfonic acid was introduced to chemically dope the polyaniline network, thereby forming a highly uniform and stable conductive network inside the coating, which further improved the electromagnetic shielding performance and infrared stealth performance of the electromagnetic shielding coating. Detailed Implementation
[0021] To better understand the above technical solution, the following will provide a detailed explanation of the technical solution in conjunction with specific implementation methods.
[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, 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.
[0023] The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.
[0024] Ti3C2T x The preparation method of MXene is as follows: First, 2 parts by mass of LiF are dissolved in 50 parts by mass of 9 mol / L hydrochloric acid solution and stirred at 40℃ for 30 min; then, 2 parts by mass of Ti3AlC2 are gradually added and stirred for 24 h, centrifuged at 5000 rpm for 5 min, then the supernatant is removed, the remaining precipitate is washed with deionized water until the pH exceeds 6, then treated with 20 mL of anhydrous ethanol under ultrasonic stirring for 2 h, and finally the precipitate is redispersed in deionized water and centrifuged at 3500 rpm for 3 min to obtain MXene dispersion of 10~20 mg / L.
[0025] The hydrogen functionality of polymethylhydrosiloxane is 0.77.
[0026] The solid content of polydimethylsiloxane is 96.7%.
[0027] The epoxy resin has a solid content of 40% and was purchased from Shanghai Wanjue Coatings Technology Co., Ltd. Example 1
[0028] A method for preparing an electromagnetic shielding coating, comprising the following steps: (1) Weighing and preparing materials: 40 parts by weight of epoxy resin, 10 parts by weight of modified polydimethylsiloxane, 26.5 parts by weight of hydrophobic filler, 27.5 parts by weight of electromagnetic shielding filler, and 5.27 parts by weight of camphor sulfonic acid; (2) Under nitrogen protection, the modified polydimethylsiloxane and electromagnetic shielding filler were added to 300 parts by weight of 1M hydrochloric acid solution and mixed. The mixture was ultrasonically dispersed for 40 min under ice bath conditions. Then, under ice bath conditions, hydrochloric acid solution containing 12 parts by weight of ammonium persulfate was added dropwise over 30 min. The mixture was then stirred for 4 h and allowed to stand for 60 min. The precipitate was then washed with hydrochloric acid solution, anhydrous ethanol and deionized water in sequence. After centrifugation until the supernatant was neutral, the precipitate was dried to obtain the first mixture. (3) After mixing and grinding the first mixture with camphor sulfonic acid for 30 min, add epoxy resin and continue mixing. Finally, add hydrophobic filler and stir for 30 min. After sonication for 10 min, add ethanol to adjust the viscosity of the coating measured by the four cups to 15 s. Then, scrape it onto the substrate and dry it at room temperature for 3 h. Place it in a drying oven at 78 ℃ for 10 h to obtain a 20 μm thick electromagnetic shielding coating.
[0029] The preparation steps of the modified polydimethylsiloxane are as follows: Under nitrogen protection, 16 parts by mass of 4-vinylaniline, 0.004 parts by mass of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum (0), and 24 parts by mass of anhydrous toluene are mixed and stirred for 10 min. Then the temperature is raised to 68°C, and a mixture of 24 parts by mass of anhydrous toluene containing 10 parts by mass of polymethylhydrosiloxane is added dropwise. The dropwise addition time is controlled at 90 min. Then the mixture is heated to 100°C and reacted for 13 h. After the reaction is completed, the mixture is rotary evaporated at 70°C to obtain the modified polydimethylsiloxane.
[0030] The preparation steps of the electromagnetic shielding filler are as follows: o-vanillin Schiff base is added to 10 mg / mL MXene dispersion and stirred for 4 h. The mass ratio of o-vanillin Schiff base to MXene is 1:5, and the electromagnetic shielding filler is obtained.
[0031] The preparation steps of the o-vanillin Schiff base are as follows: 1.52 parts by mass of o-vanillin are directly dissolved in 32 parts by mass of anhydrous ethanol, refluxed for 30 min, and then an anhydrous ethanol solution containing 1,2-phenylenediamine is added dropwise and refluxed for another 50 min. The molar ratio of 1,2-phenylenediamine to o-vanillin is 1:1. After the reaction is completed, the mixture is filtered, recrystallized in anhydrous ethanol, and dried to obtain the o-vanillin Schiff base. Example 2
[0032] A method for preparing an electromagnetic shielding coating, comprising the following steps: (1) Weighing and preparing materials: 40 parts by weight of epoxy resin, 10 parts by weight of modified polydimethylsiloxane, 27 parts by weight of hydrophobic filler, 27 parts by weight of electromagnetic shielding filler, and 5.18 parts by weight of camphor sulfonic acid; (2) Under nitrogen protection, the modified polydimethylsiloxane and the electromagnetic shielding filler were added to 150 parts by weight of 1M hydrochloric acid solution and mixed. The mixture was ultrasonically dispersed for 30 min under ice bath conditions. Then, under ice bath conditions, the hydrochloric acid solution containing 11.5 parts by weight of ammonium persulfate was added dropwise over 30 min. The mixture was then stirred for 3 h and allowed to stand for 60 min. The precipitate was then washed with hydrochloric acid solution, anhydrous ethanol and deionized water in sequence. After centrifugation until the supernatant was neutral, the precipitate was dried to obtain the first mixture. (3) After mixing and grinding the first mixture with camphor sulfonic acid for 30 min, add epoxy resin and continue mixing. Finally, add hydrophobic filler and stir for 30 min. Then, sonicate for 10 min. Then, add ethanol to adjust the viscosity of the coating measured by the four cups to 18 s. Then, scrape it onto the substrate and dry it at room temperature for 4 h. Then, place it in an 80℃ drying oven for 10 h to obtain a 30 μm thick electromagnetic shielding coating.
[0033] The preparation steps of the modified polydimethylsiloxane are as follows: Under nitrogen protection, 16.5 parts by mass of 4-vinylaniline, 0.005 parts by mass of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum (0), and 25 parts by mass of anhydrous toluene are mixed and stirred for 15 min. Then the temperature is raised to 70°C, and a mixture of 25 parts by mass of anhydrous toluene containing 10 parts by mass of polymethylhydrosiloxane is added dropwise. The dropwise addition time is controlled at 90 min. Then the mixture is heated to 105°C and reacted for 12 h. After the reaction is completed, the mixture is rotary evaporated at 70°C to obtain the modified polydimethylsiloxane.
[0034] The preparation steps of the electromagnetic shielding filler are as follows: o-vanillin Schiff base is added to 10 mg / mL MXene dispersion and stirred for 3 h. The mass ratio of o-vanillin Schiff base to MXene is 1:5, and the electromagnetic shielding filler is obtained.
[0035] The preparation steps of the o-vanillin Schiff base are as follows: 1.52 parts by mass of o-vanillin are directly dissolved in 32 parts by mass of anhydrous ethanol, refluxed for 30 min, and then an anhydrous ethanol solution containing 1,2-phenylenediamine is added dropwise and refluxed for another 60 min. The molar ratio of 1,2-phenylenediamine to o-vanillin is 1.1:1. After the reaction is completed, the mixture is filtered, recrystallized in anhydrous ethanol, and dried to obtain the o-vanillin Schiff base. Example 3
[0036] A method for preparing an electromagnetic shielding coating, comprising the following steps: (1) Weighing and preparing materials: 45 parts by weight of epoxy resin, 5 parts by weight of modified polydimethylsiloxane, 27.5 parts by weight of hydrophobic filler, 26.5 parts by weight of electromagnetic shielding filler, and 5.09 parts by weight of camphor sulfonic acid; (2) Under nitrogen protection, the modified polydimethylsiloxane and electromagnetic shielding filler were added to 300 parts by weight of 1M hydrochloric acid solution and mixed. The mixture was ultrasonically dispersed for 40 min under ice bath conditions. Then, under ice bath conditions, hydrochloric acid solution containing 11 parts by weight of ammonium persulfate was added dropwise over 30 min. The mixture was then stirred for 2 h and allowed to stand for 60 min. The precipitate was then washed with hydrochloric acid solution, anhydrous ethanol and deionized water in sequence. After centrifugation until the supernatant was neutral, the precipitate was dried to obtain the first mixture. (3) After mixing and grinding the first mixture with camphor sulfonic acid for 30 min, add epoxy resin and continue mixing. Finally, add hydrophobic filler and stir for 30 min. After sonication for 10 min, add ethanol to adjust the viscosity of the coating measured by the four cups to 20 s. Then, scrape it onto the substrate and dry it at room temperature for 5 h. Place it in an 82℃ drying oven for 10 h to obtain a 40 μm thick electromagnetic shielding coating.
[0037] The preparation steps of the modified polydimethylsiloxane are as follows: Under nitrogen protection, 17 parts by mass of 4-vinylaniline, 0.006 parts by mass of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum (0), and 26 parts by mass of anhydrous toluene are mixed and stirred for 20 min. Then, the temperature is raised to 72°C, and a mixture of 26 parts by mass of anhydrous toluene containing 10 parts by mass of polymethylhydrosiloxane is added dropwise. The dropwise addition time is controlled at 90 min. Then, the mixture is heated to 110°C and reacted for 11 h. After the reaction is completed, the mixture is rotary evaporated at 70°C to obtain the modified polydimethylsiloxane.
[0038] The preparation steps of the electromagnetic shielding filler are as follows: o-vanillin Schiff base is added to 20 mg / mL MXene dispersion and stirred for 1 h. The mass ratio of o-vanillin Schiff base to MXene is 0.75:5, and the electromagnetic shielding filler is obtained.
[0039] The preparation steps of the o-vanillin Schiff base are as follows: 1.52 parts by mass of o-vanillin are directly dissolved in 40 parts by mass of anhydrous ethanol, refluxed for 30 min, and then an anhydrous ethanol solution containing 1,2-phenylenediamine is added dropwise and refluxed for another 70 min. The molar ratio of 1,2-phenylenediamine to o-vanillin is 1.2:1. After the reaction is completed, the mixture is filtered, recrystallized in anhydrous ethanol, and dried to obtain the o-vanillin Schiff base. Comparative Example 1
[0040] The only difference between Comparative Example 1 and Example 2 is that the electromagnetic shielding coating uses polydimethylsiloxane instead of modified polydimethylsiloxane. Comparative Example 2
[0041] The only difference between Comparative Example 2 and Example 2 is that the electromagnetic shielding filler used is Ti3C2TxMXene. Comparative Example 3
[0042] The only difference between Comparative Example 3 and Example 2 is that the electromagnetic shielding filler is modified Ti3C2TxMXene with chlorogenic acid. Comparative Example 4
[0043] The only difference between Comparative Example 4 and Example 2 is that camphor sulfonic acid was not added to the electromagnetic shielding coating. Comparative Example 5
[0044] The only difference between Comparative Example 5 and Example 2 is that, in the preparation of the electromagnetic shielding coating, the raw material components are directly mixed and the viscosity of the coating is adjusted with ethanol before being scraped and applied. Example of effect
[0045] Table 1 below shows the performance test results of the electromagnetic shielding coatings of Examples 1-3 and Comparative Examples 1-5: Table 1
[0046] Table 1 shows that the electromagnetic shielding coatings prepared in Examples 1-3 have good waterproof properties, adhesion, electromagnetic shielding properties, and low infrared emissivity.
[0047] Comparative Example 1 used unmodified polydimethylsiloxane, whose coating adhesion decreased to level 2, electromagnetic shielding effectiveness decreased to 57.6 dB, and infrared emissivity increased to 0.156. This indicates that unmodified polydimethylsiloxane has poor compatibility with the epoxy resin matrix and is prone to macroscopic phase separation, which damages the integrity of the coating. At the same time, the unmodified polydimethylsiloxane side chain lacks aniline groups and cannot participate in the in-situ chemical oxidation polymerization reaction, resulting in the failure to form a dense conductive network inside the coating, thereby reducing electromagnetic shielding and infrared stealth performance.
[0048] In Comparative Example 2, the electromagnetic shielding filler used Ti3C2TxMXene. The water resistance of the electromagnetic shielding coating decreased, the adhesion decreased due to agglomeration, the electromagnetic shielding performance decreased, and the infrared emissivity increased. In Comparative Example 3, the electromagnetic shielding filler used chlorogenic acid-modified Ti3C2TxMXene. Ti3C2TxMXene had good dispersibility, the adhesion of the electromagnetic shielding coating was not affected, but the water resistance decreased, the electromagnetic shielding performance decreased, and the infrared emissivity increased. This indicates that using vanillin Schiff base to modify Ti3C2TxMXene can significantly improve the electromagnetic shielding and infrared stealth performance of the coating.
[0049] In Comparative Example 4, the electromagnetic shielding coating without camphor sulfonic acid showed a significant decrease in electromagnetic shielding effectiveness to 41.5 dB and an increase in infrared emissivity to 0.206. This indicates that the absence of camphor sulfonic acid as a chemical dopant resulted in the in-situ generated polyaniline being in a non-conductive intrinsic state, unable to form a high-conductivity carrier transport channel, thus severely weakening the coating's ability to provide electromagnetic shielding and suppress infrared radiation.
[0050] The only difference between Comparative Example 5 and Example 2 is that in the preparation of the electromagnetic shielding coating, the raw material components were directly mixed and the coating viscosity was adjusted with ethanol before being scraped. The electromagnetic shielding coating showed a decrease in water resistance and electromagnetic shielding performance, as well as an increase in infrared emissivity. This indicates that in the preparation of the electromagnetic shielding coating, the modified polydimethylsiloxane and electromagnetic shielding filler were first mixed under acidic conditions with the introduction of ammonium persulfate; then, it was mixed and dispersed with camphor sulfonic acid, epoxy resin, and hydrophobic filler in sequence, and the coating viscosity was adjusted before scraping. This can promote and improve the electromagnetic shielding, infrared stealth, and water resistance performance of the coating.
[0051] In detail, it should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. 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. An electromagnetic shielding coating, characterized in that, By mass, the raw material components include 40-45 parts epoxy resin, 5-10 parts modified polydimethylsiloxane, 26.5-27.5 parts hydrophobic filler, 26.5-27.5 parts electromagnetic shielding filler, and 5.09-5.27 parts camphor sulfonic acid.
2. The electromagnetic shielding coating according to claim 1, characterized in that, The modified polydimethylsiloxane is obtained by hydrosilylation reaction of 4-vinylaniline and polymethylhydrosiloxane.
3. The electromagnetic shielding coating according to claim 1, characterized in that, The hydrophobic filler includes modified silica.
4. The electromagnetic shielding coating according to claim 1, characterized in that, The electromagnetic shielding filler is obtained by modifying MXene with o-vanillin Schiff base; the MXene includes Ti3C2T x MXene.
5. The electromagnetic shielding coating according to claim 4, characterized in that, The o-vanillin Schiff base is obtained by reacting vanillin with o-phenylenediamine.
6. A method for preparing an electromagnetic shielding coating as described in any one of claims 1 to 5, characterized in that, The preparation steps include: (1) Weighing and preparing materials; (2) Under nitrogen protection, the modified polydimethylsiloxane and electromagnetic shielding filler were added to 150-300 parts by weight of 1M hydrochloric acid solution and mixed. The mixture was ultrasonically dispersed for 20-40 minutes under ice bath conditions. Then, under ice bath conditions, hydrochloric acid solution containing 11-12 parts by weight of ammonium persulfate was added dropwise over 30 minutes. The mixture was then stirred for 2-4 hours and allowed to stand for at least 60 minutes. The precipitate was then washed with hydrochloric acid solution, anhydrous ethanol, and deionized water in sequence. After centrifugation until the supernatant was neutral, the precipitate was dried to obtain the first mixture. (3) After mixing and grinding the first mixture with camphor sulfonic acid for at least 30 minutes, add epoxy resin and continue mixing. Finally, add hydrophobic filler and stir for at least 30 minutes. After sonication for at least 10 minutes, add ethanol to adjust the viscosity of the coating measured by the four cups to 15~20s. Then, scrape it onto the substrate and dry it at room temperature for 3~5 hours. Place it in a drying oven at 78~82℃ for 10 hours to obtain an electromagnetic shielding coating.
7. The electromagnetic shielding coating according to claim 6, characterized in that, The preparation steps of the modified polydimethylsiloxane are as follows: Under nitrogen protection, 16-17 parts by weight of 4-vinylaniline, 0.004-0.006 parts by weight of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum (0), and 24-26 parts by weight of anhydrous toluene are mixed and stirred for 10-20 minutes. Then, the temperature is raised to 68-72°C, and a mixture of 24-26 parts by weight of anhydrous toluene containing 10 parts by weight of polymethylhydrosiloxane is added dropwise. The dropwise addition time is controlled at 90 minutes. Then, the mixture is heated to 100-110°C and reacted for 11-13 hours. After the reaction is completed, the mixture is rotary evaporated at 70°C to obtain the modified polydimethylsiloxane.
8. The electromagnetic shielding coating according to claim 6, characterized in that, The preparation steps of the electromagnetic shielding filler are as follows: add o-vanillin Schiff base to 10~20mg / mL MXene dispersion and stir for 1~4h. The mass ratio of o-vanillin Schiff base to MXene is (0.75~1):5, and the electromagnetic shielding filler is obtained.
9. The electromagnetic shielding coating according to claim 8, characterized in that, The preparation steps of the o-vanillin Schiff base are as follows: 1.52 parts by mass of o-vanillin are directly dissolved in 32-40 parts by mass of anhydrous ethanol, refluxed for 30 min, and then an anhydrous ethanol solution containing 1,2-phenylenediamine is added dropwise and refluxed for another 50-70 min. The molar ratio of 1,2-phenylenediamine to o-vanillin is (1-1.2):
1. After the reaction is completed, the mixture is filtered, recrystallized in anhydrous ethanol, and dried to obtain the o-vanillin Schiff base.
10. The application of the electromagnetic shielding coating as described in any one of claims 1 to 5 in a camouflage awning, characterized in that, The thickness of the electromagnetic shielding coating in the camouflage canopy is controlled at 20~40μm.