Lightweight corrosion-resistant melamine foam electromagnetic shielding composite material and preparation method thereof

Abstract

The present application relates to a kind of light corrosion-resistant melamine foam electromagnetic shielding composite material and its preparation method, belong to electromagnetic shielding composite material technical field, according to weight parts, the preparation raw material of the light corrosion-resistant melamine foam electromagnetic shielding composite material includes: 90-97 melamine foams, 12-25 coal pitch, 3-9 copper sulfide, 0.8-2.2 outer side face attachment-reducing agent, 0.8-2.2 inner side face anti-adhesive agent.Methylphenyl silicone resin, short-chain fluorine modified acrylic resin, methyltributyl ketone oxime base silane curing agent, polyether modified polysiloxane leveling agent, fluorocarbon leveling agent, propylene glycol methyl ether, butyl acetate are prepared under reasonable proportion and process to form the outer side face attachment-reducing agent, and form the attachment-reducing layer on the side of light corrosion-resistant melamine foam electromagnetic shielding composite material and outside contact, when corrosion liquid and light corrosion-resistant melamine foam electromagnetic shielding composite material surface contact, can effectively reduce the attachment amount of material surface corrosion liquid, prolong the time of first occurrence of corrosion defect, further improve corrosion resistance.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic shielding composite material technology, specifically relating to a lightweight corrosion-resistant melamine foam electromagnetic shielding composite material and its preparation method. Background Technology

[0002] Currently, most electromagnetic shielding composite materials on the market improve corrosion resistance by directly adding corrosion-resistant fillers. However, due to the limitations of the material's lightweight and conductivity, there is a clear upper limit to the amount of corrosion-resistant components that can be added, making it difficult to fundamentally solve the problem of long-term protection.

[0003] Even if the electromagnetic shielding composite material is filled with corrosion-resistant fillers, corrosive liquids such as water vapor and salt spray can still easily adhere to and accumulate on the outer surface of the shielding material. If the corrosive medium stays and penetrates for a long time, it will gradually destroy the surface structure and then oxidize the internal conductive fillers, greatly increasing the risk of the material being corroded and failing. Summary of the Invention

[0004] The purpose of this invention is to provide a lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material and its preparation method in order to solve the above-mentioned problems.

[0005] The present invention achieves the above objectives through the following technical solutions: This invention provides a lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material. The raw materials for preparing the lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material, by weight, include: 90-97 parts melamine foam, 12-25 parts coal tar pitch, 3-9 parts copper sulfide, 0.8-2.2 parts outer surface anti-adhesion agent, 0.8-2.2 parts inner surface anti-sticking agent; The raw materials for preparing the outer surface anti-adhesion agent, by weight, include: 18-22 parts methylphenyl silicone resin, 16-20 parts short-chain fluorinated modified acrylic resin, 1.6-2.4 parts methyl tributanone oxime silane curing agent, 0.3-0.7 parts polyether modified polysiloxane leveling agent, 0.2-0.6 parts fluorocarbon leveling agent, 5-7 parts propylene glycol methyl ether, 4-7 parts butyl acetate.

[0006] As a further optimization of the present invention, the preparation process of the outer surface anti-adhesion agent is as follows: (i) Mix methyl phenyl silicone resin, short-chain fluorinated modified acrylic resin, propylene glycol methyl ether, and butyl acetate until homogeneous to obtain a mixture; (ii) Add polyether-modified polysiloxane leveling agent and fluorocarbon leveling agent to the mixture in sequence and stir until uniform; (iii) Add methyl tributanone oxime silane curing agent to step (ii) and mix and stir evenly to obtain an external surface anti-adhesion agent.

[0007] As a further optimization of the present invention, the preparation process of the external surface anti-adhesion agent includes: step (i) stirring at 300-330 r / min for 30-40 min at 24-26℃; step (ii) stirring at 330-340 r / min for 30-40 min at 24-26℃; and step (iii) stirring at 400-440 r / min for 40-50 min at 24-26℃.

[0008] As a further optimization of the present invention, the raw materials for preparing the inner surface anti-sticking agent, by weight, include: 14-16 parts vinyl silicone oil, 1.5-2.5 parts nano-fumed silica, 0.3-0.5 parts hydrophobic precipitated silica, 0.1-0.3 parts organic modified montmorillonite, 0.1-0.3 parts nano-alumina, 0.02-0.05 parts platinum-based catalyst, and 3-6 parts isopropanol.

[0009] As a further optimization of the present invention, the preparation process of the inner surface anti-sticking agent is as follows: (a) Vinyl silicone oil and isopropanol are stirred at 300-320 r / min for 20-24 min at 22-24℃. Nano-fumed silica, hydrophobic precipitated silica, organic modified montmorillonite and nano-alumina are added in sequence. The mixture is stirred at 1300-1330 r / min for 25-35 min at 22-24℃ to obtain a dispersion mixture. (ii) Add a platinum-based catalyst to the dispersion mixture and stir to mix evenly to obtain an anti-sticking agent for the inner surface.

[0010] As a further optimization of the present invention, in the preparation process of the inner surface anti-sticking agent: step (ii) is to stir at 300-320 r / min for 1-1.2 h at 22-24℃.

[0011] As a further optimization of the present invention, the particle size of the nano-vaporized silica is 10-16 nm, the particle size of the hydrophobic precipitated silica is 3-7 μm, and the particle size of the nano-alumina is 10-30 nm.

[0012] As a further optimization of the present invention, the coal tar pitch particle size is ≤200 mesh, and the copper sulfide particle size is ≤20 nm.

[0013] A method for preparing the above-mentioned lightweight corrosion-resistant melamine foam electromagnetic shielding composite material includes the following steps: S1. Add xylene to coal tar pitch and stir at 300-320 r / min for 40-50 min at room temperature to obtain a coal tar pitch xylene solution, wherein the mass ratio of coal tar pitch to xylene is 1:3-4. S2, add copper sulfide to the coal tar pitch xylene solution, stir at 45-50℃ and 800-1000r / min for 40-60min, and then ultrasonically disperse for 20-30min to obtain the impregnation dispersion; S3. The melamine foam is completely immersed in the impregnation dispersion solution. After soaking for 30-50 minutes at room temperature and pressure, the melamine foam is removed, dried naturally, and then pre-dried in an oven at 60-80℃ for 2-3 hours to obtain the conductive foam substrate. S4. The anti-adhesion agent is sprayed onto one side of the conductive foam substrate using a single-sided spraying method. The spraying air pressure is 0.2-0.4MPa, the distance between the nozzle and the foam surface is 10-18cm, the wet film coating amount is controlled at 8-15g / ㎡, the ambient temperature is 22-28℃, and the ambient relative humidity is 40-60%. Then, it is dried and cured at 65-80℃ for 1-1.5h to form an anti-adhesion thin layer on one side of the conductive foam substrate. S5. The inner anti-sticking agent is applied to the other side of the conductive foam substrate using a single-sided spraying method. The spraying air pressure is 0.2-0.4MPa, the distance between the nozzle and the foam surface is 10-18cm, the wet film coating amount is controlled at 8-15g / ㎡, the ambient temperature is 22-28℃, and the ambient relative humidity is 40-60%. Then, it is dried and cured at 60-75℃ for 1.2-2h to form an anti-sticking isolation layer on one side of the conductive foam substrate, thus obtaining a lightweight corrosion-resistant melamine foam electromagnetic shielding composite material.

[0014] The beneficial effects of this invention are as follows: Under the premise of ensuring electromagnetic shielding capability, an external anti-adhesion agent is prepared by rationally proportioning and processing methyl phenyl silicone resin, short-chain fluorinated modified acrylic resin, methyl tributanone oxime silane curing agent, polyether modified polysiloxane leveling agent, fluorocarbon leveling agent, propylene glycol methyl ether, and butyl acetate. This agent forms an anti-adhesion thin layer on the side of the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material that is in contact with the outside world. When corrosive liquid comes into contact with the surface of the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material, it can effectively reduce the amount of corrosive liquid adhering to the material surface, prolong the time before corrosion defects first appear, and further improve corrosion resistance. An anti-sticking agent for the inner surface was prepared by using vinyl silicone oil, nano-fumed silica, hydrophobic precipitated silica, organic modified montmorillonite, nano-alumina, platinum-based catalyst, and isopropanol in a reasonable ratio and process. This agent aims to prevent the inner surface of the material from sticking to the outer wall of the protective component when the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material is used to cover the internal protective component for a long time. The agent can also be removed from the protective component without affecting its subsequent use. Detailed Implementation

[0015] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0016] Unless otherwise specified, all methods used in this invention are conventional methods known to those skilled in the art, and all reagents and materials used are commercially available products.

[0017] In this invention: The melamine foam used is FT8 melamine foam manufactured by Fengte (Zhejiang) New Materials Co., Ltd. The methylphenyl silicone resin used is ChangFu MP-2950 produced by Hubei Changfu Chemical Co., Ltd. The short-chain fluorinated modified acrylic resin used is model LS-53C, manufactured by Suzhou Silicon Fluorine New Materials Co., Ltd. The methyl tributanone oxime silane curing agent used is model T-30, manufactured by Hubei Xinlantian New Materials Co., Ltd. The polyether-modified polysiloxane leveling agent used is BYK-333, manufactured by BYK Chemicals (Shanghai Branch). The fluorocarbon leveling agent used is CAPSTONE FS-61, manufactured by Chemours Chemicals (China) Co., Ltd. The propylene glycol methyl ether used is industrial grade propylene glycol methyl ether PM manufactured by Dow Chemical (China) Investment Co., Ltd. The butyl acetate used is industrial-grade n-butyl acetate produced by Jiangsu Zhengdan Chemical Industry Co., Ltd. The vinyl silicone oil used is Siwin-VF21B, manufactured by Nanjing Silicon Innovation Materials Co., Ltd. The nano-fumed silica used was AEROSIL200 manufactured by Evonik Specialty Chemicals (Shanghai) Co., Ltd. The hydrophobic precipitated silica used is HDK H18 hydrophobic precipitated silica manufactured by Wacker Chemie (China) Co., Ltd. The organically modified montmorillonite used was FHC-108 organic montmorillonite produced by Zhejiang Fenghong New Material Co., Ltd. The platinum-based catalyst used is the IOTA PC50 platinum catalyst produced by Anhui Aiyota Silicon Oil Co., Ltd. The isopropanol used is industrial anhydrous isopropanol produced by Shandong Binhua Group Co., Ltd.

[0018] I. Implementation Examples Example 1 A lightweight corrosion-resistant melamine foam electromagnetic shielding composite material, the raw materials for preparing the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material by weight are: 90 parts melamine foam, 12 parts coal tar pitch (coal tar pitch particle size is 200 mesh), 3 parts copper sulfide (copper sulfide particle size is 20 nm), 0.8 parts outer surface anti-adhesion agent, and 0.8 parts inner surface anti-sticking agent. The raw materials for preparing the external surface anti-adhesion agent, by weight, include: 18 parts methyl phenyl silicone resin, 16 parts short-chain fluorinated modified acrylic resin, 1.6 parts methyl tributanone oxime silane curing agent, 0.3 parts polyether modified polysiloxane leveling agent, 0.2 parts fluorocarbon leveling agent, 5 parts propylene glycol methyl ether, and 4 parts butyl acetate. The raw materials for preparing the inner anti-sticking agent, by weight, include: 14 parts vinyl silicone oil, 1.5 parts nano-fumed silica (nano-fumed silica with a particle size of 10 nm), 0.3 parts hydrophobic precipitated silica (hydrophobic precipitated silica with a particle size of 3 μm), 0.1 parts organic modified montmorillonite, 0.1 parts nano-alumina (nano-alumina with a particle size of 10 nm), 0.02 parts platinum-based catalyst, and 3 parts isopropanol.

[0019] A method for preparing the above-mentioned lightweight corrosion-resistant melamine foam electromagnetic shielding composite material includes the following steps: The preparation process of the external surface anti-adhesion agent is as follows: (i) Methyl phenyl silicone resin, short-chain fluorinated modified acrylic resin, propylene glycol methyl ether, and butyl acetate are mixed and stirred evenly to obtain a mixture; (ii) Polyether modified polysiloxane leveling agent and fluorocarbon leveling agent are added to the mixture in sequence and mixed and stirred evenly; (iii) Methyl tributanone oxime silane curing agent is added to step (ii) and mixed and stirred evenly to obtain the external surface anti-adhesion agent; The preparation process of the external surface anti-adhesion agent is as follows: Step (I) is to stir at 300 r / min for 30 min at 24℃; Step (II) is to stir at 330 r / min for 30 min at 24℃; Step (III) is to stir at 400 r / min for 40 min at 24℃. The preparation process of the inner surface anti-sticking agent is as follows: (i) Vinyl silicone oil and isopropanol are stirred at 300 r / min for 20 min at 22℃, and nano-fumed silica, hydrophobic precipitated silica, organic modified montmorillonite and nano-alumina are added in sequence. The mixture is stirred at 1300 r / min for 25 min at 22℃ to obtain a dispersion mixture; (ii) Platinum-based catalyst is added to the dispersion mixture and stirred until uniform to obtain the inner surface anti-sticking agent. In the preparation process of the inner anti-sticking agent: Step (II) is to stir at 300 r / min for 1 h at 22℃; Xylene was added to coal tar pitch and stirred at 300 r / min for 40 min at room temperature to obtain a coal tar pitch xylene solution, wherein the mass ratio of coal tar pitch to xylene was 1:3. Copper sulfide was added to the coal tar pitch xylene solution, and the mixture was stirred at 45℃ and 800 r / min for 40 min, followed by ultrasonic dispersion for 20 min to obtain the impregnation dispersion. Melamine foam was completely immersed in the impregnation dispersion. After soaking for 30 minutes at room temperature and pressure, the melamine foam was removed, dried naturally, and then pre-dried in a 60℃ oven for 2 hours to obtain a conductive foam substrate. The anti-adhesion agent was sprayed onto one side of the conductive foam substrate using a single-sided spraying method. The spraying pressure was 0.2 MPa, the distance between the nozzle and the foam surface was 10 cm, the wet film coating amount was controlled at 8 g / ㎡, the ambient temperature was 22℃, and the ambient relative humidity was 40%. Subsequently, it was dried and cured at 65℃ for 1 hour to form an anti-adhesion thin layer on one side of the conductive foam substrate. The inner anti-sticking agent was applied to the other side of the conductive foam substrate using a single-sided spraying method. The spraying pressure was 0.2 MPa, the distance between the nozzle and the foam surface was 10 cm, the wet film coating amount was controlled at 8 g / ㎡, the ambient temperature was 22℃, and the ambient relative humidity was 40%. Subsequently, it was dried and cured at 60℃ for 1.2 h to form an anti-sticking isolation layer on one side of the conductive foam substrate, thus obtaining a lightweight corrosion-resistant melamine foam electromagnetic shielding composite material.

[0020] Example 2 A lightweight corrosion-resistant melamine foam electromagnetic shielding composite material, wherein the raw materials for preparing the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material include: 93.5 parts melamine foam, 18.5 parts coal tar pitch (coal tar pitch particle size is 200 mesh), 6 parts copper sulfide (copper sulfide particle size is 20 nm), 1.5 parts outer surface anti-adhesion agent, and 1.5 parts inner surface anti-sticking agent; The raw materials for preparing the external surface anti-adhesion agent, by weight, include: 20 parts methyl phenyl silicone resin, 18 parts short-chain fluorinated modified acrylic resin, 2 parts methyl tributanone oxime silane curing agent, 0.5 parts polyether modified polysiloxane leveling agent, 0.4 parts fluorocarbon leveling agent, 6 parts propylene glycol methyl ether, and 5.5 parts butyl acetate. The raw materials for preparing the inner anti-stick agent, by weight, include: 15 parts vinyl silicone oil, 2 parts nano-fumed silica (the particle size of nano-fumed silica is 13nm), 0.4 parts hydrophobic precipitated silica (the particle size of hydrophobic precipitated silica is 5μm), 0.2 parts organic modified montmorillonite, 0.2 parts nano-alumina (the particle size of nano-alumina is 20nm), 0.035 parts platinum-based catalyst, and 4.5 parts isopropanol.

[0021] A method for preparing the above-mentioned lightweight corrosion-resistant melamine foam electromagnetic shielding composite material includes the following steps: The preparation process of the external surface anti-adhesion agent is as follows: (i) Methyl phenyl silicone resin, short-chain fluorinated modified acrylic resin, propylene glycol methyl ether, and butyl acetate are mixed and stirred evenly to obtain a mixture; (ii) Polyether modified polysiloxane leveling agent and fluorocarbon leveling agent are added to the mixture in sequence and mixed and stirred evenly; (iii) Methyl tributanone oxime silane curing agent is added to step (ii) and mixed and stirred evenly to obtain the external surface anti-adhesion agent; The preparation process of the external surface anti-adhesion agent is as follows: Step (I) is to stir at 315 r / min for 35 min at 25℃; Step (II) is to stir at 335 r / min for 35 min at 25℃; Step (III) is to stir at 420 r / min for 45 min at 25℃. The preparation process of the inner surface anti-sticking agent is as follows: (i) Vinyl silicone oil and isopropanol are stirred at 310 r / min for 22 min at 23℃, and nano-fumed silica, hydrophobic precipitated silica, organic modified montmorillonite and nano-alumina are added in sequence. The mixture is stirred at 1315 r / min for 30 min at 23℃ to obtain a dispersion mixture; (ii) Platinum-based catalyst is added to the dispersion mixture and stirred until uniform to obtain the inner surface anti-sticking agent. In the preparation process of the inner anti-sticking agent: Step (II) is to stir at 310 r / min for 1.1 h at 23℃; Xylene was added to coal tar pitch and stirred at 310 r / min for 45 min at room temperature to obtain a coal tar pitch xylene solution, wherein the mass ratio of coal tar pitch to xylene was 1:3.5. Copper sulfide was added to the coal tar pitch xylene solution, and the mixture was stirred at 47.5℃ and 900 r / min for 50 min, followed by ultrasonic dispersion for 25 min to obtain the impregnation dispersion. The melamine foam was completely immersed in the impregnation dispersion and soaked for 40 minutes at room temperature and pressure. Then, the melamine foam was removed, dried naturally, and pre-dried in a 70℃ oven for 2.5 hours to obtain the conductive foam substrate. The anti-adhesion agent was sprayed onto one side of the conductive foam substrate using a single-sided spraying method. The spraying pressure was 0.3 MPa, the distance between the nozzle and the foam surface was 14 cm, the wet film coating amount was controlled at 11.5 g / ㎡, the ambient temperature was 25℃, and the ambient relative humidity was 50%. Subsequently, it was dried and cured at 72.5℃ for 1.25 h to form an anti-adhesion thin layer on one side of the conductive foam substrate. The inner anti-sticking agent was applied to the other side of the conductive foam substrate using a single-sided spraying method. The spraying pressure was 0.3 MPa, the distance between the nozzle and the foam surface was 14 cm, the wet film coating amount was controlled at 11.5 g / ㎡, the ambient temperature was 25℃, and the ambient relative humidity was 50%. Subsequently, it was dried and cured at 67.5℃ for 1.6 h to form an anti-sticking isolation layer on one side of the conductive foam substrate, thus obtaining a lightweight corrosion-resistant melamine foam electromagnetic shielding composite material.

[0022] Example 3 A lightweight corrosion-resistant melamine foam electromagnetic shielding composite material, wherein the raw materials for preparing the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material include: 97 parts melamine foam, 25 parts coal tar pitch (coal tar pitch particle size is 200 mesh), 9 parts copper sulfide (copper sulfide particle size is 20 nm), 2.2 parts outer surface anti-adhesion agent, and 2.2 parts inner surface anti-sticking agent. The raw materials for preparing the external surface anti-adhesion agent, by weight, include: 22 parts methyl phenyl silicone resin, 20 parts short-chain fluorinated modified acrylic resin, 2.4 parts methyl tributanone oxime silane curing agent, 0.7 parts polyether modified polysiloxane leveling agent, 0.6 parts fluorocarbon leveling agent, 7 parts propylene glycol methyl ether, and 7 parts butyl acetate. The raw materials for preparing the inner anti-sticking agent, by weight, include: 16 parts vinyl silicone oil, 2.5 parts nano-fumed silica (the particle size of nano-fumed silica is 16nm), 0.5 parts hydrophobic precipitated silica (the particle size of hydrophobic precipitated silica is 7μm), 0.3 parts organic modified montmorillonite, 0.3 parts nano-alumina (the particle size of nano-alumina is 30nm), 0.05 parts platinum-based catalyst, and 6 parts isopropanol.

[0023] A method for preparing the above-mentioned lightweight corrosion-resistant melamine foam electromagnetic shielding composite material includes the following steps: The preparation process of the external surface anti-adhesion agent is as follows: (i) Methyl phenyl silicone resin, short-chain fluorinated modified acrylic resin, propylene glycol methyl ether, and butyl acetate are mixed and stirred evenly to obtain a mixture; (ii) Polyether modified polysiloxane leveling agent and fluorocarbon leveling agent are added to the mixture in sequence and mixed and stirred evenly; (iii) Methyl tributanone oxime silane curing agent is added to step (ii) and mixed and stirred evenly to obtain the external surface anti-adhesion agent; The preparation process of the external surface anti-adhesion agent is as follows: Step (I) is to stir at 330 r / min for 40 min at 26℃; Step (II) is to stir at 340 r / min for 40 min at 26℃; Step (III) is to stir at 440 r / min for 50 min at 26℃. The preparation process of the inner surface anti-sticking agent is as follows: (i) Vinyl silicone oil and isopropanol are stirred at 320 r / min for 24 min at 24℃, and nano-fumed silica, hydrophobic precipitated silica, organic modified montmorillonite and nano-alumina are added in sequence. The mixture is stirred at 1330 r / min for 35 min at 24℃ to obtain a dispersion mixture; (ii) Platinum catalyst is added to the dispersion mixture and stirred until uniform to obtain the inner surface anti-sticking agent. In the preparation process of the inner anti-sticking agent: Step (II) is to stir at 320 r / min for 1.2 h at 24℃; Xylene was added to coal tar pitch and stirred at 320 r / min for 50 min at room temperature to obtain a coal tar pitch xylene solution, wherein the mass ratio of coal tar pitch to xylene was 1:4. Copper sulfide was added to the coal tar pitch xylene solution, and the mixture was stirred at 50°C and 1000 r / min for 60 min, followed by ultrasonic dispersion for 30 min to obtain the impregnation dispersion. Melamine foam was completely immersed in the impregnation dispersion solution. After soaking for 50 minutes at room temperature and pressure, the melamine foam was removed, dried naturally, and then pre-dried in an oven at 80℃ for 3 hours to obtain a conductive foam substrate. The anti-adhesion agent was sprayed onto one side of the conductive foam substrate using a single-sided spraying method. The spraying pressure was 0.4 MPa, the distance between the nozzle and the foam surface was 18 cm, the wet film coating amount was controlled at 15 g / ㎡, the ambient temperature was 28℃, and the ambient relative humidity was 60%. Subsequently, it was dried and cured at 80℃ for 1.5 h to form an anti-adhesion thin layer on one side of the conductive foam substrate. The inner anti-sticking agent was applied to the other side of the conductive foam substrate using a single-sided spraying method. The spraying pressure was 0.4 MPa, the distance between the nozzle and the foam surface was 18 cm, the wet film coating amount was controlled at 15 g / ㎡, the ambient temperature was 28℃, and the ambient relative humidity was 60%. Subsequently, it was dried and cured at 75℃ for 2 hours to form an anti-sticking isolation layer on one side of the conductive foam substrate, thus obtaining a lightweight corrosion-resistant melamine foam electromagnetic shielding composite material.

[0024] II. Comparative Example 1. Replace the coal tar pitch in Example 2 with the coal tar pitch / epoxy resin described in Table 1 below, and the remaining steps are the same as in Example 2: ; Table 1 2. Replace the copper sulfide in Example 2 with the nickel sulfide / iron sulfide / zinc sulfide listed in Table 2 below, and the remaining steps are the same as in Example 2: ; Table 2 3. Replace 1.5 parts of the external surface anti-adhesion agent in Example 2 with the external surface anti-adhesion agent described in Table 3 below, and the remaining steps are the same as in Example 2: ; Table 3 4. Comparative Example 12 A lightweight corrosion-resistant melamine foam electromagnetic shielding composite material, the raw materials for preparing the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material by weight include: 93.5 parts melamine foam, 18.5 parts coal tar pitch (coal tar pitch particle size is 200 mesh), 6 parts copper sulfide (copper sulfide particle size is 20 nm), and 3 parts inner surface anti-sticking agent. The raw materials for preparing the inner anti-stick agent, by weight, include: 15 parts vinyl silicone oil, 2 parts nano-fumed silica (the particle size of nano-fumed silica is 13nm), 0.4 parts hydrophobic precipitated silica (the particle size of hydrophobic precipitated silica is 5μm), 0.2 parts organic modified montmorillonite, 0.2 parts nano-alumina (the particle size of nano-alumina is 20nm), 0.035 parts platinum-based catalyst, and 4.5 parts isopropanol.

[0025] A method for preparing the above-mentioned lightweight corrosion-resistant melamine foam electromagnetic shielding composite material includes the following steps: The preparation process of the inner surface anti-sticking agent is as follows: (i) Vinyl silicone oil and isopropanol are stirred at 310 r / min for 22 min at 23℃, and nano-fumed silica, hydrophobic precipitated silica, organic modified montmorillonite and nano-alumina are added in sequence. The mixture is stirred at 1315 r / min for 30 min at 23℃ to obtain a dispersion mixture; (ii) Platinum-based catalyst is added to the dispersion mixture and stirred until uniform to obtain the inner surface anti-sticking agent. In the preparation process of the inner anti-sticking agent: Step (II) is to stir at 310 r / min for 1.1 h at 23℃; Xylene was added to coal tar pitch and stirred at 310 r / min for 45 min at room temperature to obtain a coal tar pitch xylene solution, wherein the mass ratio of coal tar pitch to xylene was 1:3.5. Copper sulfide was added to the coal tar pitch xylene solution, and the mixture was stirred at 47.5℃ and 900 r / min for 50 min, followed by ultrasonic dispersion for 25 min to obtain the impregnation dispersion. The melamine foam was completely immersed in the impregnation dispersion and soaked for 40 minutes at room temperature and pressure. Then, the melamine foam was removed, dried naturally, and pre-dried in a 70℃ oven for 2.5 hours to obtain the conductive foam substrate. An anti-sticking agent was applied to one side of a conductive foam substrate using a single-sided spraying method. The spraying pressure was 0.3 MPa, the distance between the nozzle and the foam surface was 14 cm, the wet film coating amount was controlled at 11.5 g / ㎡, the ambient temperature was 25℃, and the ambient relative humidity was 50%. Subsequently, it was dried and cured at 67.5℃ for 1.6 h to form an anti-sticking isolation layer on one side of the conductive foam substrate, thus obtaining a lightweight corrosion-resistant melamine foam electromagnetic shielding composite material.

[0026] 5. Replace the inner surface anti-adhesive agent in Example 2 with the inner surface anti-adhesive agent described in Table 4 below, and the remaining steps are the same as in Example 2: ; Table 4 6. Comparative Example 17 A lightweight corrosion-resistant melamine foam electromagnetic shielding composite material, the raw materials for preparing the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material by weight include: 93.5 parts melamine foam, 18.5 parts coal tar pitch (coal tar pitch particle size is 200 mesh), 6 parts copper sulfide (copper sulfide particle size is 20 nm), and 3 parts external surface anti-adhesion agent. The raw materials for preparing the external surface anti-adhesion agent, by weight, include: 20 parts methyl phenyl silicone resin, 18 parts short-chain fluorinated modified acrylic resin, 2 parts methyl tributanone oxime silane curing agent, 0.5 parts polyether modified polysiloxane leveling agent, 0.4 parts fluorocarbon leveling agent, 6 parts propylene glycol methyl ether, and 5.5 parts butyl acetate.

[0027] A method for preparing the above-mentioned lightweight corrosion-resistant melamine foam electromagnetic shielding composite material includes the following steps: The preparation process of the external surface anti-adhesion agent is as follows: (i) Methyl phenyl silicone resin, short-chain fluorinated modified acrylic resin, propylene glycol methyl ether, and butyl acetate are mixed and stirred evenly to obtain a mixture; (ii) Polyether modified polysiloxane leveling agent and fluorocarbon leveling agent are added to the mixture in sequence and mixed and stirred evenly; (iii) Methyl tributanone oxime silane curing agent is added to step (ii) and mixed and stirred evenly to obtain the external surface anti-adhesion agent; The preparation process of the external surface anti-adhesion agent is as follows: Step (I) is to stir at 315 r / min for 35 min at 25℃; Step (II) is to stir at 335 r / min for 35 min at 25℃; Step (III) is to stir at 420 r / min for 45 min at 25℃. Xylene was added to coal tar pitch and stirred at 310 r / min for 45 min at room temperature to obtain a coal tar pitch xylene solution, wherein the mass ratio of coal tar pitch to xylene was 1:3.5. Copper sulfide was added to the coal tar pitch xylene solution, and the mixture was stirred at 47.5℃ and 900 r / min for 50 min, followed by ultrasonic dispersion for 25 min to obtain the impregnation dispersion. The melamine foam was completely immersed in the impregnation dispersion and soaked for 40 minutes at room temperature and pressure. Then, the melamine foam was removed, dried naturally, and pre-dried in a 70℃ oven for 2.5 hours to obtain the conductive foam substrate. The anti-adhesion agent was sprayed onto one side of the conductive foam substrate using a single-sided spraying method. The spraying pressure was 0.3 MPa, the distance between the nozzle and the foam surface was 14 cm, the wet film coating amount was controlled at 11.5 g / ㎡, the ambient temperature was 25℃, and the ambient relative humidity was 50%. Subsequently, it was dried and cured at 72.5℃ for 1.25 h to form an anti-adhesion thin layer on one side of the conductive foam substrate, thus obtaining a lightweight corrosion-resistant melamine foam electromagnetic shielding composite material.

[0028] III. Testing Experiments 1. Shielding performance test experiment ①The shielding performance of the lightweight corrosion-resistant melamine foam electromagnetic shielding composite materials prepared in Examples 1-3 and Comparative Examples 1-17 was tested according to the flange coaxial method of GB / T 30142-2013 "Method for measuring the shielding effectiveness of planar electromagnetic shielding materials". The results are shown in Table 5 below. ; Table 5 2. Corrosion resistance test experiment ①The corrosion resistance of the lightweight corrosion-resistant melamine foam electromagnetic shielding composite materials prepared in Example 2 and Comparative Examples 6-12 was tested according to GB / T 10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test" (Neutral Salt Spray NSS). The results are shown in Table 6 below. ②The surface liquid residue adhesion of the lightweight corrosion-resistant melamine foam electromagnetic shielding composite materials prepared in Example 2 and Comparative Examples 6-12 was tested according to GB / T 9274-1988 "Determination of resistance to liquid media for paints and varnishes". The results are shown in Table 7 below. in: 1) Sample specifications: 100mm×100mm×3mm lightweight corrosion-resistant melamine foam electromagnetic shielding composite material, with only the outer anti-adhesion thin layer exposed, and the bonding side sealed and protected; 2) Ambient temperature: 25℃; 3) Sample placement method: The sample is fixed at a 30° angle to simulate the natural flow of condensation during assembly of the whole machine; 4) Procedure: Quantitatively take 2 mL of 5 wt% NaCl saline solution and evenly drop it onto the outer surface of the sample. After standing for 1 minute, wipe the sample surface with a lint-free cloth to collect the residual liquid. Weigh the residual liquid and calculate the amount of saline solution adhering to the surface, in mg / cm³. 2 ; 5) Evaluation criteria: The lower the value of the amount of adhering residue, the easier it is for the corrosive liquid to slide off and the less it stays on the material surface, the lower the probability of corrosion induction, and the better the resistance to condensation corrosion. ③ The critical failure test of the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material prepared in Example 2 and Comparative Examples 6-12 was conducted at a constant temperature of 40°C for full immersion. The results are shown in Table 7 below. in: 1) The sample specifications and sealing method are consistent with those in ② above; 2) Soaking temperature: 40℃ constant temperature; 3) Judgment criteria: After continuous immersion, when the sample shows any of the following phenomena: surface whitening, pitting, coating blistering, or shielding effectiveness attenuation > 10%, the time is recorded as the dwell time (h) when the corrosion defect first appears. 4) Evaluation criteria: The greater the failure time value, the stronger the surface barrier membrane's resistance to media penetration and the better its long-term corrosion resistance. ; Table 6 ; Table 7 III. Anti-adhesion Test Experiment ①The anti-adhesion ability of the lightweight corrosion-resistant melamine foam electromagnetic shielding composite materials prepared in Example 2 and Comparative Examples 13-17 was tested according to HG / T 4363-2012 "Test Method for Anti-adhesion Performance of Plastic Anti-adhesion Coating". The results are shown in Table 8 below. The test conditions are as follows: 1) Bonding substrate: Aluminum casing of electronic devices (simulating the bonding interface of components) 2) Applied pressure load: 50 kPa 3) High-temperature environment: 80 ℃ constant temperature oven, pressure maintained for 72 h. 4) Sample size: 100 mm × 100 mm lightweight corrosion-resistant melamine foam electromagnetic shielding composite material; ; Table 8 As can be seen from Table 5 above, compared with Examples 1, 3 and Comparative Examples 1-17, the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material prepared in Example 2 has the best electromagnetic shielding ability. The average shielding efficiency of the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material reached 78.5dB under reasonable ratio and process of melamine foam, coal tar pitch, copper sulfide, outer surface anti-adhesion agent and inner surface anti-sticking agent. As can be seen from Tables 6 and 7 above, compared with Comparative Examples 1-12, the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material prepared in Example 2 has the best corrosion resistance. An anti-adhesion agent was prepared on the outer surface by means of methyl phenyl silicone resin, short-chain fluorinated modified acrylic resin, methyl tributanone oxime silane curing agent, polyether modified polysiloxane leveling agent, fluorocarbon leveling agent, propylene glycol methyl ether, and butyl acetate in a reasonable ratio and process. An anti-adhesion thin layer is formed on the side of the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material that is in contact with the outside. When corrosive liquid comes into contact with the surface of the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material, it can effectively reduce the amount of corrosive liquid adhering to the material surface, prolong the time before the first appearance of corrosion defects, and further improve the corrosion resistance.

[0029] As can be seen from Table 8 above, compared with Comparative Examples 13-17, the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material prepared in Example 2 has the best anti-adhesion ability. In particular, the inner anti-adhesion agent was prepared by using vinyl silicone oil, nano-fumed silica, hydrophobic precipitated silica, organic modified montmorillonite, nano-alumina, platinum catalyst, and isopropanol in a reasonable ratio and process. When the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material covers and contacts the internal protective component (metal aluminum shell of electronic device) for a long time, it can avoid the adhesion between the inner side of the material and the outer wall of the protective component. When the material is removed from the protective component, it does not affect the subsequent use of the material and the protective component.

[0030] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material, characterized in that, The raw materials for preparing the lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material, by weight, include: 90-97 parts melamine foam, 12-25 parts coal tar pitch, 3-9 parts copper sulfide, 0.8-2.2 parts outer surface anti-adhesion agent, 0.8-2.2 parts inner surface anti-sticking agent; The raw materials for preparing the outer surface anti-adhesion agent, by weight, include: 18-22 parts methylphenyl silicone resin, 16-20 parts short-chain fluorinated modified acrylic resin, 1.6-2.4 parts methyl tributanone oxime silane curing agent, 0.3-0.7 parts polyether modified polysiloxane leveling agent, 0.2-0.6 parts fluorocarbon leveling agent, 5-7 parts propylene glycol methyl ether, 4-7 parts butyl acetate.

2. The lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material according to claim 1, characterized in that, The preparation process of the external surface anti-adhesion agent is as follows: (i) Mix methyl phenyl silicone resin, short-chain fluorinated modified acrylic resin, propylene glycol methyl ether, and butyl acetate until homogeneous to obtain a mixture; (ii) Add polyether-modified polysiloxane leveling agent and fluorocarbon leveling agent to the mixture in sequence and stir until uniform; (iii) Add methyl tributanone oxime silane curing agent to step (ii) and mix and stir evenly to obtain an external surface anti-adhesion agent.

3. The lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material according to claim 2, characterized in that, The preparation process of the external surface anti-adhesion agent is as follows: Step (i) is to stir at 300-330 r / min for 30-40 min at 24-26℃; Step (ii) is to stir at 330-340 r / min for 30-40 min at 24-26℃; Step (iii) is to stir at 400-440 r / min for 40-50 min at 24-26℃.

4. The lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material according to claim 1, characterized in that, The raw materials for preparing the inner surface anti-sticking agent, by weight, include: 14-16 parts vinyl silicone oil, 1.5-2.5 parts nano-fumed silica, 0.3-0.5 parts hydrophobic precipitated silica, 0.1-0.3 parts organic modified montmorillonite, 0.1-0.3 parts nano-alumina, 0.02-0.05 parts platinum-based catalyst, and 3-6 parts isopropanol.

5. The lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material according to claim 4, characterized in that, The preparation process of the inner surface anti-sticking agent is as follows: (a) Vinyl silicone oil and isopropanol are stirred at 300-320 r / min for 20-24 min at 22-24℃. Nano-fumed silica, hydrophobic precipitated silica, organic modified montmorillonite and nano-alumina are added in sequence. The mixture is stirred at 1300-1330 r / min for 25-35 min at 22-24℃ to obtain a dispersion mixture. (ii) Add a platinum-based catalyst to the dispersion mixture and stir to mix evenly to obtain an anti-sticking agent for the inner surface.

6. The lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material according to claim 5, characterized in that, In the preparation process of the inner surface anti-sticking agent: step (ii) is to stir at 300-320 r / min for 1-1.2 h at 22-24℃.

7. The lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material according to claim 4, characterized in that, The nano-sized fumed silica has a particle size of 10-16 nm, the hydrophobic precipitated silica has a particle size of 3-7 μm, and the nano-sized alumina has a particle size of 10-30 nm.

8. The lightweight, corrosion-resistant melamine foam electromagnetic shielding composite material according to claim 1, characterized in that, The coal tar pitch has a particle size ≤200 mesh, and the copper sulfide has a particle size ≤20 nm.

9. A method for preparing the lightweight corrosion-resistant melamine foam electromagnetic shielding composite material according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Add xylene to coal tar pitch and stir at 300-320 r / min for 40-50 min at room temperature to obtain a coal tar pitch xylene solution, wherein the mass ratio of coal tar pitch to xylene is 1:3-4. S2, add copper sulfide to the coal tar pitch xylene solution, stir at 45-50℃ and 800-1000r / min for 40-60min, and then ultrasonically disperse for 20-30min to obtain the impregnation dispersion; S3. The melamine foam is completely immersed in the impregnation dispersion solution. After soaking for 30-50 minutes at room temperature and pressure, the melamine foam is removed, dried naturally, and then pre-dried in an oven at 60-80℃ for 2-3 hours to obtain the conductive foam substrate. S4. The anti-adhesion agent is sprayed onto one side of the conductive foam substrate using a single-sided spraying method. The spraying air pressure is 0.2-0.4MPa, the distance between the nozzle and the foam surface is 10-18cm, the wet film coating amount is controlled at 8-15g / ㎡, the ambient temperature is 22-28℃, and the ambient relative humidity is 40-60%. Then, it is dried and cured at 65-80℃ for 1-1.5h to form an anti-adhesion thin layer on one side of the conductive foam substrate. S5. The inner anti-sticking agent is applied to the other side of the conductive foam substrate using a single-sided spraying method. The spraying air pressure is 0.2-0.4MPa, the distance between the nozzle and the foam surface is 10-18cm, the wet film coating amount is controlled at 8-15g / ㎡, the ambient temperature is 22-28℃, and the ambient relative humidity is 40-60%. Then, it is dried and cured at 60-75℃ for 1.2-2h to form an anti-sticking isolation layer on one side of the conductive foam substrate, thus obtaining a lightweight corrosion-resistant melamine foam electromagnetic shielding composite material.