An anti-corrosion electromagnetic shielding coating and its preparation method and application

Abstract

The present invention discloses an anti-corrosion electromagnetic shielding coating, its preparation method, and application, relating to the field of electromagnetic shielding technology. The coating comprises a conductive layer and a magnetic permeable layer, the magnetic permeable layer being located above the conductive layer. The present invention achieves an electromagnetic shielding effect by forming the magnetic permeable layer on the conductive layer, wherein the thickness of the conductive layer is smaller than that of the magnetic permeable layer. The coating utilizes the synergistic effect of the conductive layer's reflection attenuation of electromagnetic waves and the magnetic permeable layer's absorption loss of electromagnetic waves to achieve electromagnetic wave shielding.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic shielding, and in particular to an anti-corrosion electromagnetic shielding coating and a preparation method and application thereof. Background Art

[0002] With the continuous innovation and development of modern industrial technology, in the field of electronic information industry, various types of communication equipment and electronic products are increasing rapidly and becoming more and more popular. At the same time, the rapid development of electronic equipment has enabled my country's modern national defense capabilities to reach an unprecedented level. However, electronic and electrical equipment are very likely to generate electromagnetic radiation and are susceptible to electromagnetic interference from the outside world while working, thereby causing electromagnetic wave pollution in the air and causing serious interference to the normal operation of electronic and electrical equipment. In particular, electromagnetic interference from the outside world to electronic and electrical equipment can cause equipment damage and personal injury in severe cases, causing serious economic losses to business and national defense. Therefore, certain protective measures must be taken, and a functional electromagnetic shielding coating is usually applied to the surface of electronic and electrical equipment.

[0003] The electromagnetic shielding coating after the electromagnetic shielding coating is completely film-formed and cured can block the transmission path of external electromagnetic waves, making it difficult for electromagnetic waves to enter the interior of electronic and electrical equipment, thereby protecting precision equipment. The electromagnetic shielding coating is composed of film-forming resin, shielding agent, curing agent, dispersant, anti-settling agent and solvent. Among them, the electromagnetic properties of the shielding agent are the key to determining the shielding effect of the electromagnetic shielding coating. To obtain electromagnetic shielding coatings with high shielding efficiency, it is necessary to add a large dose of conductive filler to the coating. This will make the highly active conductive filler more easily exposed to corrosive media. Therefore, it is difficult to give full play to the high shielding efficiency and corrosion resistance of electromagnetic shielding coatings. Gui Taijiang of the Marine Chemical Industry Research Institute [1] et al. invented a corrosion-resistant electromagnetic shielding coating, but its shielding effectiveness in the range of 1MHz to 1GHz is only 26 to 68dB, and the stability of the coating can only be guaranteed after 144 hours of neutral salt spray and 120 hours of damp heat testing. Zheng Kai et al. from the 33rd Institute of China Electronics Technology Group Corporation invented a corrosion-resistant electromagnetic shielding coating for aluminum alloy surfaces, which can maintain stable properties after 528 hours of neutral salt spray testing. However, these corrosion-resistant electromagnetic shielding coatings have low shielding effectiveness and short corrosion resistance life, making it difficult to meet the requirements of long-term service in corrosive environments such as the ocean. Therefore, there is an urgent need to develop a low-cost, corrosion-resistant, high-performance electromagnetic shielding coating. Summary of the Invention

[0004] In response to the shortcomings of the aforementioned background technology, the present invention primarily addresses the low shielding effectiveness and short corrosion life of existing corrosion-resistant electromagnetic shielding coatings, which make it difficult to meet the requirements for long-term service in corrosive environments such as the ocean. The present invention provides an anti-corrosion electromagnetic shielding coating, its preparation method, and its application. This coating achieves an electromagnetic shielding effect by forming a magnetically conductive layer on a conductive layer, where the thickness of the conductive layer is less than that of the magnetically conductive layer. The coating utilizes the synergistic effect of the reflection attenuation of electromagnetic waves by the conductive layer and the absorption loss of electromagnetic waves by the magnetically conductive layer.

[0005] The first object of the present invention is to provide an anti-corrosion electromagnetic shielding coating, which comprises a conductive layer and a magnetic conductive layer, wherein the magnetic conductive layer is located on the conductive layer;

[0006] The conductive layer is formed by curing a conductive coating, wherein the conductive coating comprises the following components in parts by weight: 35-50 parts of resin, 3-15 parts of curing agent, 20-120 parts of conductive filler, 1-2 parts of dispersant, 1-2 parts of anti-settling agent, and 10-75 parts of solvent;

[0007] The magnetic conductive layer is formed by curing a magnetic conductive coating, wherein the magnetic conductive coating comprises the following components in parts by weight: 35-50 parts of resin, 3-15 parts of curing agent, 20-120 parts of magnetic conductive filler, 1-2 parts of dispersant, 1-2 parts of anti-settling agent, and 10-75 parts of solvent;

[0008] The conductive filler is one or more of gold powder, silver powder, silver-coated aluminum powder, nickel-coated graphite powder, silver-coated copper powder, carbon black, carbon nanotubes, and carbon fibers;

[0009] The magnetic conductive filler is flaky nickel powder.

[0010] Preferably, the flaky nickel powder is prepared according to the following steps: adding spherical nickel powder, zirconium oxide grinding balls and anhydrous ethanol to a ball mill in proportion, setting the ball milling speed and ball milling time, filtering after the ball milling operation is completed, and drying at 75-85° C. to obtain the flaky nickel powder.

[0011] Preferably, the particle size of the spherical nickel powder is 3~15μm; the mass ratio of the spherical nickel powder to the zirconia grinding balls is 1:3~15, and the mass ratio of the spherical nickel powder to the anhydrous ethanol is 1:1~3; the ball milling speed is 100~300r / min, and the ball milling time is 5~20h.

[0012] Preferably, the conductive layer has a thickness of 20-100 μm; and the magnetic conductive layer has a thickness of 200-1000 μm.

[0013] Preferably, the resin is one or more of silicone resin, epoxy resin, acrylic resin and polyurethane resin.

[0014] Preferably, the curing agent is selected from one or more of polyamide, polyetheramine, and fatty amine;

[0015] The dispersant is DISPERBYK-110 dispersant;

[0016] The anti-settling agent is selected from paraffin and / or organic bentonite.

[0017] Preferably, the solvent is selected from one or more of toluene, xylene, acetone, butanone, isopropyl alcohol, propylene glycol methyl ether acetate, and n-butanol.

[0018] A second object of the present invention is to provide a method for preparing an anti-corrosion electromagnetic shielding coating, which is characterized by comprising the following steps:

[0019] Weighing the resin, curing agent, conductive filler, dispersant, anti-settling agent and solvent in parts by weight, mixing the weighed raw materials of each component, and stirring them evenly using a homogenizer to obtain the conductive coating;

[0020] Weighing the resin, curing agent, magnetic conductive filler, dispersant, anti-settling agent and solvent according to weight, mixing the weighed raw materials, and stirring them evenly using a homogenizer to obtain the magnetic conductive coating;

[0021] The conductive coating is applied to the surface of the substrate by air spraying, and then heated and cured to prepare the conductive layer;

[0022] The magnetic conductive coating is coated on the surface of the conductive layer by air spraying, and heated and cured to prepare the magnetic conductive layer.

[0023] Preferably, the stirring speed of the homogenizer is 500-3000 r / min, and the stirring time is 5-20 min;

[0024] The process parameters of the air spraying method are: spraying pressure 0.2~0.8MPa, spraying distance 10~60cm, spraying angle 80~100°, and spray gun moving speed 15~45cm / s;

[0025] The heating and heat preservation process parameters are: curing temperature 60-120° C., and curing time 6-12 hours.

[0026] The third object of the present invention is to provide an anti-corrosion electromagnetic shielding coating for use in electromagnetic shielding.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention provides an anti-corrosion electromagnetic shielding coating, its preparation method and application. The present invention prepares a magnetic conductive layer on a conductive layer, and the thickness of the conductive layer is smaller than that of the magnetic conductive layer. The invention utilizes the synergistic effect of the reflection attenuation of electromagnetic waves by the conductive layer and the absorption loss of electromagnetic waves by the magnetic conductive layer to achieve the shielding effect of electromagnetic waves. In addition, see Figure 2 As shown, the magnetic layer uses flaky fillers, which significantly extend the propagation path of the corrosive medium within the magnetic layer. Furthermore, the standard electrode potential of the magnetic layer filler (-0.23V) is much lower than the standard electrode potential of the conductive layer (0.337~3.7V). When the corrosive medium invades the coating, the magnetic filler acts as a sacrificial anode to protect the conductive layer, maximizing the shielding effectiveness of the coating after corrosion. Compared with pure conductive layer shielding coatings, this dual-coating structure can ensure an electromagnetic shielding effectiveness greater than 60dB in the 100MHz~18GHz range after 3000 hours of acidic salt spray exposure while reducing production costs. Compared with existing electromagnetic shielding coating materials, the electromagnetic shielding coating material provided by the present invention has the advantages of lower cost, higher shielding effectiveness, and better corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the structure of the anti-corrosion electromagnetic shielding coating.

[0030] Figure 2 Schematic diagram of the extended corrosion path for the magnetic permeable layer.

[0031] Figure 3 This is a scanning electron microscope image of the homemade flaky nickel powder in Example 5.

[0032] Figure 4 These are surface photographs of Example 1, Comparative Example 1, and Comparative Example 2 after 3000 hours of acidic salt spray corrosion.

[0033] Among them, 1 is the conductive layer and 2 is the magnetic conductive layer. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below with reference to specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

[0035] The purpose of the present invention is to provide an anti-corrosion electromagnetic shielding coating and a preparation method and application thereof.

[0036] To achieve the above purpose, see Figure 1 As shown, an anti-corrosion electromagnetic shielding coating comprises a conductive layer 1 and a magnetic conductive layer 2, wherein the magnetic conductive layer 2 is located on the conductive layer 1;

[0037] The thickness of the conductive layer 1 is 20-100 μm; the thickness of the magnetic conductive layer 2 is 200-1000 μm.

[0038] The conductive layer 1 is formed by curing a conductive coating, wherein the conductive coating comprises the following components in parts by weight: 35-50 parts of resin, 3-15 parts of curing agent, 20-120 parts of conductive filler, 1-2 parts of dispersant, 1-2 parts of anti-settling agent, and 10-75 parts of solvent;

[0039] The magnetic conductive layer 2 is formed by curing a magnetic conductive coating, wherein the magnetic conductive coating comprises the following components in parts by weight: 35-50 parts of resin, 3-15 parts of curing agent, 20-120 parts of magnetic conductive filler, 1-2 parts of dispersant, 1-2 parts of anti-settling agent, and 10-75 parts of solvent.

[0040] The conductive and magnetic fillers used in the present invention possess excellent magnetic and electrical conductivity, ensuring the shielding effectiveness of the electromagnetic shielding coating. The resin selected in the present invention exhibits excellent wettability for these types of electromagnetic shielding fillers. During the coating curing process, the resin spreads effectively on the surface of the electromagnetic shielding fillers, forming an extremely thin nano-resin layer. This not only ensures mutual adhesion between the electromagnetic shielding fillers but also allows the electromagnetic shielding filler particles to form conductive or magnetic circuits through tunneling or magnetic exchange. The curing agent exhibits excellent attack activity, lowering the resin's curing temperature, accelerating curing, and increasing the resin's crosslinking density. The dispersant and anti-settling agent promote uniform distribution of the electromagnetic shielding fillers within the resin through electrostatic and steric interactions, further enhancing the resin's wettability. The solvent dilutes the coating, ensuring processability, and improves the coating's rheological properties to achieve directional distribution of the electromagnetic shielding fillers within the coating, further increasing the coating's electrical and magnetic conductivity, thereby enhancing the coating's shielding effectiveness.

[0041] The conductive filler is one or more of gold powder, silver powder, silver-coated aluminum powder, nickel-coated graphite powder, silver-coated copper powder, carbon black, carbon nanotubes, and carbon fibers; the gold powder is a dark gold powder with a particle size of 10 to 15 μm; the silver powder is a dark silver powder with a D50 of 7 μm; the aluminum powder is a bright silver powder with a D50 of 15 μm; the carbon black is a nano-scale black powder; the carbon nanotube is a black powder with a diameter of approximately 15 nm and an aspect ratio of approximately 1000; and the carbon fiber is a black fibrous solid with a length of approximately 1.5 mm. The conductive filler is a product of Shaanxi General Nanotechnology Co., Ltd.

[0042] The magnetic conductive filler is flaky nickel powder.

[0043] The flaky nickel powder is prepared according to the following steps: adding spherical nickel powder, zirconium oxide grinding balls and anhydrous ethanol into a ball mill in proportion, setting the ball milling speed and ball milling time, filtering after the ball milling operation is completed, and drying at 75-85° C. to obtain the flaky nickel powder with a D50 of 37 μm.

[0044] In one embodiment, the preparation steps of flaky nickel powder are as follows: spherical nickel powder, zirconium oxide grinding balls and anhydrous ethanol are added to a ball mill in a mass ratio of 1:3 to 15:1 to 3, the ball mill speed is set to 100 to 300 r / min at room temperature, the ball milling time is 5 to 20 hours, and after the ball milling operation is completed, the flaky nickel powder magnetic filler is obtained by filtering and drying. The SEM image of the flaky nickel powder used in Example 5 is shown as follows. Figure 3 shown.

[0045] The particle size of the spherical nickel powder is 3~15μm; the mass ratio of the spherical nickel powder to the zirconia grinding balls is 1:3~15, and the mass ratio of the spherical nickel powder to the anhydrous ethanol is 1:1~3; the ball milling speed is 100~300r / min, and the ball milling time is 5~20h.

[0046] The resin is one or more of silicone resin, epoxy resin, acrylic resin and polyurethane resin, all of which are products of Hubei Xinsihai Chemical Co., Ltd.

[0047] The curing agent is selected from one or more of polyamide, polyetheramine, and fatty amine; polyamide is a medium-viscosity brown liquid, polyetheramine is a low-viscosity light yellow liquid, and fatty amine is a medium-viscosity transparent liquid, all of which are products of Hubei Xinsihai Chemical Co., Ltd.

[0048] The dispersant is DISPERBYK-110 dispersant; the dispersant is an oily liquid dispersant and is a product of Shenzhen Pasto Chemical Co., Ltd.

[0049] The anti-settling agent is selected from paraffin wax and / or organic bentonite, both of which are products of Hubei Xinsihai Chemical Co., Ltd. The paraffin anti-settling agent is a milky white paste, and the organic bentonite is a white or light yellow powder.

[0050] The solvent is selected from one or more of toluene, xylene, acetone, butanone, isopropyl alcohol, propylene glycol methyl ether acetate, and n-butanol, and is a product of Nanjing Hecheng Chemical Co., Ltd. Toluene is a colorless, volatile liquid with a special aromatic odor; xylene is a colorless, transparent liquid with a special aromatic odor; acetone is a colorless, flammable liquid with a mint odor; butanone is a colorless, transparent liquid with a mint-like odor; isopropyl alcohol is a colorless, transparent liquid with an odor similar to a mixture of ethanol and acetone; propylene glycol methyl ether acetate is a colorless, hygroscopic liquid with a special odor; and n-butanol is a colorless, transparent liquid with an alcoholic odor.

[0051] A second aspect of the present invention provides a method for preparing an anti-corrosion electromagnetic shielding coating, comprising the following steps:

[0052] Weighing the resin, curing agent, conductive filler, dispersant, anti-settling agent and solvent in parts by weight, mixing the weighed raw materials of each component, and stirring them evenly using a homogenizer to obtain the conductive coating;

[0053] Weighing the resin, curing agent, magnetic conductive filler, dispersant, anti-settling agent and solvent according to weight, mixing the weighed raw materials, and stirring them evenly using a homogenizer to obtain the magnetic conductive coating;

[0054] The conductive coating is applied to the surface of the substrate by air spraying, and then heated and cured to prepare the conductive layer. The specific process is as follows:

[0055] The conductive coating is loaded into a spraying device and evenly sprayed on the surface of the substrate in an S-shaped path. The thickness of a single spray is less than 30 μm. After each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 to 15 minutes. The sample is then placed in an oven for heating and insulation to solidify the conductive coating sprayed on the surface of the substrate to obtain a first conductive prefabricated layer. The preparation process of the first conductive prefabricated layer is repeated until the thickness of the obtained conductive prefabricated layer reaches the designed thickness to obtain a conductive layer.

[0056] The magnetic conductive coating is applied to the surface of the conductive layer by air spraying, and then heated and cured to prepare the magnetic conductive layer. The specific process is as follows:

[0057] The magnetic conductive coating is loaded into a spraying device and sprayed evenly on the surface of the conductive layer in an S-shaped path, with a spraying thickness of less than 30 μm; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 to 15 minutes, and then the sample is placed in an oven for heating and insulation to solidify the magnetic conductive coating sprayed on the surface of the conductive layer, thereby obtaining a first layer of magnetic conductive prefabricated layer; the preparation process of the first layer of magnetic conductive prefabricated layer is repeated until the thickness of the obtained magnetic conductive prefabricated layer reaches the designed thickness, thereby obtaining a magnetic conductive layer; that is, the anti-corrosion electromagnetic shielding coating is obtained.

[0058] Wherein, the stirring speed of the homogenizer is 500~3000r / min, and the stirring time is 5~20min;

[0059] The process parameters of the air spraying method are: spraying pressure 0.2~0.8MPa, spraying distance 10~60cm, spraying angle 80~100°, and spray gun moving speed 15~45cm / s;

[0060] The heating and heat preservation process parameters are: curing temperature 60-120° C., and curing time 6-12 hours.

[0061] The third aspect of the present invention provides an application of an anti-corrosion electromagnetic shielding coating in electromagnetic shielding

[0062] It should be noted that the experimental methods used in the present invention are all conventional methods unless otherwise specified; the reagents and materials used are all commercially available unless otherwise specified.

[0063] Example

[0064] Step 1. Preparation of substrate

[0065] An epoxy plastic plate with a thickness of 0.5 mm was used as a substrate, and the surface of the substrate was cleaned with anhydrous ethanol to ensure that there were no dust particles on the surface of the substrate.

[0066] Step 2. Prepare the coating

[0067] Step 2.1 Preparation of conductive coating

[0068] Resin, curing agent, conductive filler, dispersant, anti-settling agent and solvent are weighed in parts by weight, the weighed raw materials of each component are mixed, and stirred evenly using a homogenizer to obtain a conductive coating.

[0069] Among them, the stirring speed of the homogenizer is 500~3000r / min, and the stirring time is 5~20min.

[0070] Step 2.2 Preparation of magnetic conductive coating

[0071] Resin, curing agent, magnetic conductive filler, dispersant, anti-settling agent and solvent are weighed in parts by weight, the weighed raw materials of each component are mixed, and stirred evenly using a homogenizer to obtain a magnetic conductive coating.

[0072] Among them, the stirring speed of the homogenizer is 500~3000r / min, and the stirring time is 5~20min.

[0073] Step 3. Prepare the conductive layer

[0074] The conductive coating is applied to the surface of the substrate by air spraying, and then heated and cured to prepare a conductive layer;

[0075] The specific process is as follows: the conductive coating is loaded into the spraying device and sprayed evenly on the surface of the substrate in an S-shaped path, with a spraying thickness of less than 30 μm; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 to 15 minutes, and then the sample is placed in an oven and kept warm at 60 to 120°C for 6 to 12 hours to solidify the conductive coating sprayed on the surface of the substrate to obtain the first conductive prefabricated layer; the preparation process of the first conductive prefabricated layer is repeated until the thickness of the obtained conductive prefabricated layer reaches the designed thickness to obtain a conductive layer.

[0076] Among them, the process parameters of the air spray method are: spraying pressure 0.2~0.8MPa, spraying distance 10~60cm, spraying angle 80~100°, and spray gun moving speed 15~45cm / s.

[0077] Step 4. Prepare the magnetic conductive layer

[0078] The magnetic conductive coating is applied on the surface of the conductive layer by air spraying, and then heated and cured to prepare the magnetic conductive layer;

[0079] The specific process is as follows: the magnetic conductive coating is loaded into the spraying device and sprayed evenly on the surface of the conductive layer in an S-shaped path, with a spraying thickness of less than 30 μm; after each 0.1 mm coating is sprayed, the sample is dried at room temperature for 10 to 15 minutes, and then the sample is placed in an oven and kept warm at 60 to 100°C for 8 to 12 hours to solidify the magnetic conductive coating sprayed on the surface of the conductive layer to obtain the first magnetic conductive prefabricated layer; the preparation process of the first magnetic conductive prefabricated layer is repeated until the thickness of the obtained magnetic conductive prefabricated layer reaches the designed thickness to obtain a magnetic conductive layer; that is, an anti-corrosion electromagnetic shielding coating is obtained.

[0080] Among them, the process parameters of the air spray method are: spraying pressure of 0.2~0.8MPa, spraying distance of 10~60cm, spraying angle of 80~100°, and spray gun moving speed of 15~45cm / s.

[0081] The process parameters of the magnetic conductive filler in each embodiment are shown in Table 1.

[0082] Table 1 Process parameters of magnetic conductive fillers in various embodiments

[0083]

[0084] The composition of the anti-corrosion electromagnetic shielding coating in each embodiment is shown in Table 2.

[0085] Table 2 Composition of the anti-corrosion electromagnetic shielding coating in each embodiment

[0086]

[0087] The process parameters of each embodiment are shown in Table 3.

[0088] Table 3 Process parameters of each embodiment

[0089]

[0090] Comparative Example 1

[0091] An electromagnetic shielding coating comprising only a magnetic conductive layer. The preparation method for the magnetic conductive layer filler is the same as that described in Example 1 in Table 1. Specifically, 1 kg of nickel powder, 3 kg of zirconium oxide ball milling beads, and 1 kg of anhydrous ethanol are added to a stirred ball mill. After ball milling at 100 rpm for 5 hours, the mixture is filtered and dried at 80°C to obtain a flaky nickel powder magnetic conductive filler. A magnetic conductive coating is prepared by combining 35 parts of epoxy resin, 3 parts of polyamide, 20 parts of flaky nickel powder magnetic conductive filler, 1 part of DISPERBYK-110, 1 part of organobentonite, 7 parts of xylene, 5 parts of propylene glycol methyl ether acetate, and 3 parts of n-butanol according to the method described above. A coating having a thickness of 220 μm is prepared using the process parameters of Example 1 in Table 3.

[0092] Comparative Example 2

[0093] An electromagnetic shielding coating includes only a conductive layer, and the conductive layer is prepared by:

[0094] A conductive coating was prepared by the method described above using 35 parts of silicone resin, 3 parts of polyamide, 60 parts of silver powder, 1 part of DISPERBYK-110, 1 part of organic bentonite, 7 parts of xylene, 5 parts of propylene glycol methyl ether acetate, and 3 parts of n-butanol. A coating with a thickness of 220 μm was prepared using the process parameters of Example 1 in Table 3.

[0095] To illustrate the microscopic morphology of the flaky nickel powder prepared in the embodiment of the present invention, the morphology of the flaky nickel powder was observed using a TESCAN Vega 3 scanning electron microscope in accordance with JY / T 0584-2020 "General Rules for Scanning Electron Microscope Analysis Methods". The results are as follows: Figure 3 As shown in the figure, it can be seen that the nickel flakes have a high degree of flake formation, a large diameter-to-thickness ratio, and no breakage due to stress.

[0096] In order to illustrate the corrosion resistance and electromagnetic shielding effectiveness of the anti-corrosion electromagnetic shielding coating prepared in the embodiment of the present invention, the corrosion resistance and electromagnetic shielding effectiveness of the prepared anti-corrosion electromagnetic shielding coating were tested according to GJB150.11A-2009 "Laboratory Environmental Test Method for Military Equipment" and GJB 8820-2015 "Measurement Method for Shielding Effectiveness of Electromagnetic Shielding Materials", respectively. The test results are shown in Tables 4 and 5.

[0097] Table 4 Acid salt spray resistance test results of various examples

[0098]

[0099] It can be seen from Table 4 that the anti-corrosion electromagnetic shielding coating prepared in the embodiment of the present invention has no peeling, blistering, wrinkling, cracking or falling off on the surface of the coating in the acidic salt spray environment test, indicating that the prepared anti-corrosion electromagnetic shielding coating has excellent corrosion resistance.

[0100] Table 5 Electromagnetic shielding effectiveness test results of various examples

[0101]

[0102] It can be seen from Table 5 that the anti-corrosion electromagnetic shielding coating prepared in the embodiment of the present invention has an excellent shielding effect on electromagnetic waves in the 100 MHz ~ 18 GHz band, and its electromagnetic shielding effectiveness value is higher than 60 dB, reaching the military level, and meeting the shielding requirements of special fields.

[0103] Table 6 Electromagnetic shielding effectiveness test results of each embodiment and comparative example before and after 3000h salt spray

[0104]

[0105] As can be seen from Table 6, the electrical conductivity and magnetic permeability of Comparative Example 1 (only the magnetic conductive layer) are low, and the shielding effectiveness is much lower than that of Example 1. Comparative Example 2 (only the conductive layer) has good electrical conductivity and high shielding effectiveness before corrosion, but the shielding effectiveness decays rapidly after 3000 hours of acidic salt spray, and the shielding effectiveness is less than 60dB in the range of 100MHz~18GHz. For Example 1, its shielding effectiveness in the range of 100MHz~18GHz before and after corrosion is greater than 60dB. Surface photos of Example 1 and Comparative Examples 1 and 2 after 3000 hours of acidic salt spray corrosion are shown in the figure below. Figure 4 As shown, thanks to the excellent absorption loss and anti-corrosion effect of the magnetic conductive layer, the anti-corrosion electromagnetic shielding coating of the present invention not only has excellent shielding effectiveness, but also has good corrosion resistance.

[0106] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An anti-corrosion electromagnetic shielding coating, characterized in that: The coating comprises a conductive layer and a magnetic conductive layer, wherein the magnetic conductive layer is located on the conductive layer; The conductive layer is formed by curing a conductive coating, wherein the conductive coating comprises the following components in parts by weight: 35-50 parts of resin, 3-15 parts of curing agent, 20-120 parts of conductive filler, 1-2 parts of dispersant, 1-2 parts of anti-settling agent, and 10-75 parts of solvent; The magnetic conductive layer is formed by curing a magnetic conductive coating, wherein the magnetic conductive coating comprises the following components in parts by weight: 35-50 parts of resin, 3-15 parts of curing agent, 20-120 parts of magnetic conductive filler, 1-2 parts of dispersant, 1-2 parts of anti-settling agent, and 10-75 parts of solvent; The conductive filler is one or more of gold powder, silver powder, silver-coated aluminum powder, nickel-coated graphite powder, silver-coated copper powder, carbon black, carbon nanotubes, and carbon fibers; The magnetic conductive filler is flaky nickel powder; The thickness of the conductive layer is 20-100 μm; the thickness of the magnetic conductive layer is 200-1000 μm.

2. The anti-corrosion electromagnetic shielding coating according to claim 1, characterized in that: The flaky nickel powder is prepared according to the following steps: adding spherical nickel powder, zirconium oxide grinding balls and anhydrous ethanol into a ball mill in proportion, setting the ball milling speed and ball milling time, filtering after the ball milling operation is completed, and drying at 75-85° C. to obtain the flaky nickel powder.

3. The anti-corrosion electromagnetic shielding coating according to claim 2, characterized in that: The particle size of the spherical nickel powder is 3~15μm; the mass ratio of the spherical nickel powder to the zirconia grinding balls is 1:3~15, and the mass ratio of the spherical nickel powder to the anhydrous ethanol is 1:1~3; the ball milling speed is 100~300r / min, and the ball milling time is 5~20h.

4. The anti-corrosion electromagnetic shielding coating according to claim 1, characterized in that: The resin is one or more of silicone resin, epoxy resin, acrylic resin and polyurethane resin.

5. The anti-corrosion electromagnetic shielding coating according to claim 1, characterized in that: The curing agent is selected from one or more of polyamide, polyetheramine and fatty amine; The dispersant is DISPERBYK-110 dispersant; The anti-settling agent is selected from paraffin and / or organic bentonite.

6. The anti-corrosion electromagnetic shielding coating according to claim 1, characterized in that: The solvent is selected from one or more of toluene, xylene, acetone, butanone, isopropyl alcohol, propylene glycol methyl ether acetate, and n-butanol.

7. A method for preparing the anti-corrosion electromagnetic shielding coating according to any one of claims 1 to 6, characterized in that: The following steps are involved: Weighing the resin, curing agent, conductive filler, dispersant, anti-settling agent and solvent in parts by weight, mixing the weighed raw materials of each component, and stirring them evenly using a homogenizer to obtain the conductive coating; Weighing the resin, curing agent, magnetic conductive filler, dispersant, anti-settling agent and solvent according to weight, mixing the weighed raw materials, and stirring them evenly using a homogenizer to obtain the magnetic conductive coating; The conductive coating is applied to the surface of the substrate by air spraying, and then heated and cured to prepare the conductive layer; The magnetic conductive coating is coated on the surface of the conductive layer by air spraying, and heated and cured to prepare the magnetic conductive layer.

8. The method for preparing the anti-corrosion electromagnetic shielding coating according to claim 7, characterized in that: The stirring speed of the homogenizer is 500~3000r / min, and the stirring time is 5~20min; The process parameters of the air spraying method are: spraying pressure 0.2~0.8MPa, spraying distance 10~60cm, spraying angle 80~100°, and spray gun moving speed 15~45cm / s; The heating and heat preservation process parameters are: curing temperature 60-120° C., and curing time 6-12 hours.

9. Use of the anti-corrosion electromagnetic shielding coating according to any one of claims 1 to 6 in electromagnetic shielding.

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