CN114437396A - Electromagnetic shielding composite foam with sandwich structure and preparation method thereof - Google Patents
Electromagnetic shielding composite foam with sandwich structure and preparation method thereof Download PDFInfo
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- H05K9/0073—Shielding materials
- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
- H05K9/009—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive fibres, e.g. metal fibres, carbon fibres, metallised textile fibres, electro-conductive mesh, woven, non-woven mat, fleece, cross-linked
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Abstract
The invention discloses an electromagnetic shielding composite foam with a sandwich structure and a preparation method thereof, wherein the preparation method comprises the following steps: s1: attaching conductive metal particles on the surface of the filler to obtain the high-conductivity filler; s2: blending the high-conductivity filler with a polymer to prepare a conductive filler-polymer composite material; s3: preparing a pure polymer material layer with the thickness of 0.1-5 mm; s4: placing a pure polymer material layer in the middle, and placing the conductive filler-polymer composite material obtained in S2 on two sides for compounding to obtain a composite material with a sandwich structure; s5: and (3) saturating the composite material with the sandwich structure obtained in the step (S4) for 1 min-48 h under the conditions of 30-280 ℃ and 0.5-50 MPa in a foaming gas environment, then decompressing to normal pressure at the rate of 0.1-30 MPa/S, and cooling to room temperature to obtain the composite material. The composite foam has good conductivity and electromagnetic shielding performance, and the material density is low.
Description
Technical Field
The invention belongs to the technical field of electromagnetic shielding composite materials, and particularly relates to electromagnetic shielding composite foam with a sandwich structure and a preparation method thereof.
Background
With the continuous development of electronic information and mobile communication industries, a large number of new electronic products are coming into the lives and works of people. The use of electronic components provides a lot of convenience for human beings on one hand, and also causes serious electromagnetic radiation pollution on the other hand, which causes a series of social and environmental problems. Electromagnetic radiation pollution can not only affect the normal operation of televisions, broadcasting, satellites, medical and communication equipment and the like, but also cause harm to the development and functions of human life systems and seriously damage human health. In order to prevent various problems caused by electromagnetic radiation pollution, it is necessary to develop materials with electromagnetic shielding performance to protect electronic equipment, and not emit excessive electromagnetic waves to the outside while endowing the equipment with certain electromagnetic radiation blocking capability.
In recent years, polymer-based electromagnetic shielding composite materials have attracted attention due to the characteristics of light weight, easiness in processing, corrosion resistance, adjustable conductivity and the like. For the traditional polymer electromagnetic shielding composite material with uniformly dispersed filler, in order to make the shielding effect of the traditional polymer electromagnetic shielding composite material reach the requirement of commercial application, more conductive filler (such as carbon fiber, carbon black, carbon nanotube and the like) is often required to be added into a polymer matrix, so that good lap joint among filler particles is realized. The addition of excessive conductive filler not only greatly increases the manufacturing cost and the processing difficulty of the material, but also improves the weight of the shielding matrix, weakens the light weight advantage of the polymer-based electromagnetic shielding material and limits the application of the polymer-based electromagnetic shielding material in the fields of traffic, mobile communication, military engineering and the like.
Disclosure of Invention
Aiming at the prior art, the invention provides an electromagnetic shielding composite foam with a sandwich structure and a preparation method thereof, and aims to solve the problems of excessive addition of conductive filler, high manufacturing cost and processing difficulty, heavy weight of a shielding matrix and the like in the prior art.
In order to achieve the purpose, the invention adopts the technical scheme that: the preparation method of the sandwich structure electromagnetic shielding composite foam comprises the following steps:
s1: attaching conductive metal particles on the surface of the filler to obtain the high-conductivity filler;
s2: blending the high-conductivity filler with a polymer to prepare a conductive filler-polymer composite material;
s3: preparing a pure polymer material layer with the thickness of 0.1-5 mm;
s4: placing a pure polymer material layer in the middle, and placing the conductive filler-polymer composite material obtained in S2 on two sides for compounding to obtain a composite material with a sandwich structure;
s5: and (3) saturating the composite material with the sandwich structure obtained in the step (S4) for 1 min-48 h under the conditions of 30-280 ℃ and 0.5-50 MPa in a foaming gas environment, then decompressing to normal pressure at the rate of 0.1-30 MPa/S, and cooling to room temperature to obtain the composite material.
The invention adopts the means of structural design (sandwich structure) to ensure that the conductive filler particles are selectively distributed in a specific area of the composite material, thereby further strengthening the integrity of the filler network and enhancing the shielding efficiency.
According to the invention, the high-pressure gas foaming technology is utilized to introduce the multiple holes into the sandwich structure composite material to prepare the sandwich structure electromagnetic shielding composite foam, the method can effectively reduce the density of the material, realize the light weight of the electromagnetic shielding composite material, and improve the shielding efficiency of the material.
On the basis of the technical scheme, the invention can be further improved as follows.
Further, the high-conductivity filler is prepared by the following steps:
SS 1: coarsening and sensitizing filler particles in sequence;
SS 2: and adding the sensitized filler particles into chemical silver plating solution, chemical copper plating solution, chemical nickel plating solution, chemical aluminum plating solution, chemical iron plating solution or chemical tungsten plating solution according to the feed liquor ratio of 1g: 5-100 mL, then adding a reducing agent, reacting for 1 min-10h, and then washing and drying to obtain the composite filler.
A layer of metal conductive particles is attached to the surface of the filler by a chemical plating method, so that the filler has excellent conductivity, the overlapping efficiency of the filler in a polymer matrix is greatly improved, and the electromagnetic shielding performance of the composite material is enhanced.
Further, the filler particles are non-metallic inorganic particles, carbon-based particles, or metal fibers.
Further, the non-metallic inorganic particles are at least one of nano-silica, calcium carbonate, glass fiber, quartz glass fiber, ceramic fiber, carbon fiber, asbestos fiber, basalt fiber, montmorillonite and barium sulfate; the carbon-based particles are at least one of carbon fibers, carbon black, carbon nanotubes, carbon quantum dots and football alkene; the metal fiber is at least one of stainless steel fiber and copper fiber.
Further, the conductive filler-polymer composite is prepared by the following steps: and blending the polymer and the conductive filler according to the mass ratio of 1: 2-50: 1 at 50-400 ℃ and 10-1000 rpm for 5min-10h to obtain the conductive filler.
Further, the conductive filler-polymer composite is prepared by the following steps: dissolving a polymer in a solvent, adding conductive filler which is 1/50-2 times of the polymer in mass, stirring to uniformly disperse the filler, and volatilizing the solvent to obtain the conductive polymer.
Further, the solvent is ethanol, methanol, isopropanol, ethylene glycol, diethyl ether, acetone, hexane, cyclohexane, pentane, heptane, octane, aniline, butanone, chloroform, dimethylamine, carbon tetrachloride, N-heptanol, tetrahydrofuran, benzene, toluene, xylene, ethylbenzene, butyl acetate, chloroform, formic acid, dimethyl sulfoxide, chlorobenzene, dichlorobenzene, dichloromethane, trichloroethylene, or N-methylpyrrolidone.
Further, the polymer is polyethylene, polypropylene, polycarbonate, polystyrene, polyvinyl chloride, polytetrafluoroethylene, polyamide, vinyl acetate copolymer, polyethylene terephthalate, polymethyl methacrylate, polycarbonate, polyurethane, polylactic acid, polyglycolic acid, polycaprolactone, polyvinyl alcohol, epoxy resin, urea resin, furan resin, melamine formaldehyde resin, silicone resin, polyarylate, acrylate, phenol resin, polyether ether ketone, polysulfone, polyphenylene sulfide, polyimide, styrene-butadiene rubber, isoprene rubber, butyl rubber, ethylene-propylene rubber, fluorine rubber, silicone rubber, thermoplastic polystyrene elastomer, thermoplastic polyolefin elastomer, thermoplastic copolyester elastomer, thermoplastic polyamide elastomer, or thermoplastic polyurethane elastomer.
Further, the foaming gas is air, nitrogen, carbon dioxide, helium, argon, petroleum ether, methane, ethane, propane, butane, pentane, hexane, heptane, n-pentane, n-hexane, n-heptane, dichloromethane, or trichlorofluoromethane.
The invention has the beneficial effects that:
1. the invention obtains the high-conductivity metal-plated filler by a chemical plating method, effectively strengthens the conductive path of filler particles after the conductive filler is compounded with the polymer, and improves the conductivity of the composite material.
2. The electromagnetic shielding composite foam with the sandwich structure prepared by the invention has good conductivity and electromagnetic shielding performance, simultaneously, the density of the material can be further reduced by introducing the foam holes, the electromagnetic shielding efficiency of the composite foam can reach 49dB, and the density of the material is as low as 0.3g/cm3The requirements of the electromagnetic shielding material in commercial application are greatly exceeded, and the application field range of the electromagnetic shielding material is widened.
3. The high-pressure gas foaming method used by the invention has the advantages of simple operation and low cost.
Drawings
FIG. 1 is a scanning electron microscope image of a metal nickel-attached carbon fiber prepared in example 3;
FIG. 2 is a scanning electron microscope image of a cross section of the composite foam with electromagnetic shielding in a sandwich structure prepared in example 3;
fig. 3 shows the electromagnetic shielding effectiveness of the composite foam with electromagnetic shielding in a sandwich structure prepared in example 5.
Detailed Description
The following examples are provided to illustrate specific embodiments of the present invention.
Example 1
A preparation method of sandwich structure electromagnetic shielding composite foam comprises the following steps:
(1) preparation of highly conductive fillers
Slowly adding 1g of nano-silica into 20mL of dilute sulfuric acid, mechanically stirring for 2h, repeatedly washing with distilled water, filtering to be neutral, adding the obtained product into a stannous chloride aqueous solution, mechanically stirring, adding the sensitized nano-silica into 50mL of chemical tungsten plating solution (5 g/L of sodium tungstate and 5g/L of sodium hypophosphite), slowly adding a sodium citrate aqueous solution, reacting for 1min under magnetic stirring, and washing, filtering and drying to obtain the metal tungsten loaded nano-silica.
(2) Preparation of metal tungsten loaded nano silicon dioxide conductive filler-polylactic acid composite material layer
Placing 8g of polylactic acid and 2g of metal tungsten loaded nano silicon dioxide in an internal mixer, blending for 5min at 170 ℃ under the condition of 120 r/min, and then treating the mixture through a die pressing process to obtain the metal tungsten loaded nano silicon dioxide-polylactic acid composite material layer.
(3) And (3) preparing a pure polylactic acid composite material layer with the thickness of 1.0mm by adopting the same process flow in the step (2).
(4) Preparation of sandwich structure metal tungsten loaded nano silicon dioxide-polylactic acid composite material
And (3) laminating the composite material layer prepared in the step (2) and a pure polylactic acid material with the thickness of 1.0mm, and pressing to obtain the metal tungsten loaded nano silicon dioxide-polylactic acid composite material with a sandwich structure, wherein the middle layer is pure polylactic acid, and the surface layer is a conductive filler-polylactic acid composite material.
(5) High pressure gas foaming
Cutting the tungsten-loaded nano silicon dioxide-polylactic acid composite material with the sandwich structure obtained in the step (4) into a regular shape, placing the material in a high-pressure reaction kettle, heating, introducing carbon dioxide gas, saturating at 140 ℃ and 20MPa for 30min, then reducing the pressure relief rate to normal pressure at 5MPa/s, taking out a foamed sample, and drying in an oven to finally obtain the polylactic acid electromagnetic shielding composite foam with the sandwich structure.
Example 2
A preparation method of sandwich structure electromagnetic shielding composite foam comprises the following steps:
(1) preparation of highly conductive fillers
Slowly adding 1g of montmorillonite into 100mL of dilute sulfuric acid, mechanically stirring for 10h, repeatedly washing with distilled water, filtering to be neutral, adding the montmorillonite into a stannous chloride aqueous solution, mechanically stirring, adding the sensitized montmorillonite into 100mL of chemical silver plating solution (5 g/L of silver nitrate and 10g/L of ammonia water), slowly adding a sodium citrate aqueous solution, reacting for 2h under magnetic stirring, washing, filtering and drying to obtain the metallic silver loaded montmorillonite.
(2) Preparation of metal silver loaded montmorillonite conductive filler-polyimide composite material layer
And (2) placing 9g of polyimide and 4.5g of metal silver loaded montmorillonite in an internal mixer, blending for 10 hours at 400 ℃ under the condition of 1000 revolutions per minute, and then treating the mixture through a mould pressing process to obtain the metal silver loaded montmorillonite-polyimide composite material layer.
(3) And (3) preparing a pure polyimide composite material layer with the thickness of 2.0mm by adopting the same process flow in the step (2).
(4) Preparation of sandwich structure metal silver loaded montmorillonite-polyimide composite material
And (3) laminating the composite material layer prepared in the step (2) and a pure polyimide material with the thickness of 2.0mm, and pressing to obtain the metal silver loaded montmorillonite-polyimide composite material with the sandwich structure, wherein the middle layer is pure polyimide, and the surface layer is a conductive filler-polyimide composite material.
(5) High pressure gas foaming
Cutting the sandwich structure silver-loaded montmorillonite-polyimide composite material obtained in the step (4) into a regular shape, placing the material in a high-pressure reaction kettle, heating, introducing carbon dioxide, saturating at 280 ℃ and 50MPa for 48h, then reducing the pressure relief rate to normal pressure at 30MPa/s, taking out a foamed sample, and drying in an oven to finally obtain the polyimide electromagnetic shielding composite foam with the sandwich structure.
Example 3
A preparation method of sandwich structure electromagnetic shielding composite foam comprises the following steps:
(1) preparation of highly conductive fillers
Slowly adding 1g of carbon fiber into 5mL of dilute sulfuric acid, mechanically stirring for 5min, repeatedly washing with distilled water, filtering to be neutral, adding the carbon fiber into a stannous chloride aqueous solution, mechanically stirring, adding the sensitized carbon fiber into 5mL of chemical nickel plating solution (40 g/L of nickel sulfate, 10g/L of sodium pyrophosphate, 5g/L of sodium hypophosphite, 5g/L of thiourea and 10mL of ammonia water), slowly adding a sodium citrate aqueous solution, reacting for 30min under magnetic stirring, and washing, suction filtering and drying to obtain the metallic nickel loaded carbon fiber.
(2) Preparation of metallic nickel loaded carbon fiber conductive filler-silicone rubber composite material layer
9g of silicon rubber and 1g of metallic nickel loaded carbon fiber are placed in an internal mixer, blended for 5min at the temperature of 50 ℃ and at the speed of 180 r/min, and then the mixture is processed by a mould pressing process to obtain the metallic nickel loaded carbon fiber-silicon rubber composite material layer.
(3) And (3) preparing a pure silicon rubber composite material layer with the thickness of 3.0mm by adopting the same process flow in the step (2).
(4) Preparation of sandwich structure metal nickel loaded carbon fiber-silicone rubber composite material
And (3) superposing the composite material layer prepared in the step (2) and a pure silicon rubber material layer with the thickness of 3.0mm, and pressing to obtain the metal nickel-loaded carbon fiber-silicon rubber composite material with a sandwich structure, wherein the middle layer is pure silicon rubber, and the surface layer is a conductive filler-silicon rubber composite material.
(5) High pressure gas foaming
Cutting the nickel-loaded carbon fiber-silicone rubber composite material with the sandwich structure obtained in the step (3) into a regular shape, placing the material in a high-pressure reaction kettle, heating, introducing nitrogen, saturating at 30 ℃ and under the pressure of 0.5MPa for 1min, then reducing the pressure relief rate of 0.5MPa/s to the normal pressure, taking out a foamed sample, and drying in a drying oven to finally obtain the silicone rubber electromagnetic shielding composite foam with the sandwich structure.
Example 4
A preparation method of sandwich structure electromagnetic shielding composite foam comprises the following steps:
(1) preparation of highly conductive fillers
Slowly adding 1g of glass fiber into 50mL of dilute sulfuric acid, mechanically stirring for 1h, repeatedly washing with distilled water, filtering to be neutral, adding the obtained product into a stannous chloride aqueous solution, mechanically stirring, adding the sensitized glass fiber into 50mL of chemical copper plating solution (100 g/L of copper chloride, 10g/L of disodium ethylenediamine tetraacetic acid and 1g/L of boric acid), slowly adding a sodium citrate aqueous solution, reacting for 2h under magnetic stirring, and washing, filtering and drying to obtain the metallic copper loaded glass fiber.
(2) Preparation of metal copper loaded glass fiber conductive filler-epoxy resin composite material layer
Adding 10g of epoxy resin and 0.2g of metal copper loaded glass fiber into acetone, mechanically stirring under the ultrasonic power condition of 3000W to fully dissolve the epoxy resin, pouring the mixture into a mold, and then placing the mold in a fume hood until the solvent is completely volatilized to obtain the metal copper loaded glass fiber-epoxy resin composite material layer.
(3) And (3) preparing a pure epoxy resin composite material layer with the thickness of 4.0mm by adopting the same process flow in the step (2).
(4) Preparation of sandwich structure metal copper load glass fiber-epoxy resin composite material
And (3) laminating and pressing the composite material layer prepared in the step (2) and a pure epoxy resin material with the thickness of 4.0mm to obtain the metal copper loaded glass fiber-epoxy resin composite material with a sandwich structure, wherein the middle layer is made of pure epoxy resin, and the surface layer is made of a conductive filler-epoxy resin composite material.
(5) High pressure gas foaming
Cutting the copper-loaded glass fiber-epoxy resin composite material with the sandwich structure obtained in the step (4) into a regular shape, placing the material in a high-pressure reaction kettle, heating, introducing methane, saturating at 120 ℃ under the pressure of 10MPa for 10h, then reducing the pressure to normal pressure at the pressure relief rate of 5MPa/s, taking out a foamed sample, and drying in a drying oven to finally obtain the epoxy resin electromagnetic shielding composite foam with the sandwich structure.
Example 5
A preparation method of sandwich structure electromagnetic shielding composite foam comprises the following steps:
(1) preparation of highly conductive fillers
Slowly adding 1g of carbon black into 80mL of dilute sulfuric acid, mechanically stirring for 2h, repeatedly washing with distilled water and filtering to be neutral, then adding the carbon black into a stannous chloride aqueous solution, mechanically stirring, adding the sensitized carbon black into 80mL of chemical plating aluminum liquid (5 g/L of aluminum chloride and 20g/L of sodium hypophosphite), slowly adding a sodium citrate aqueous solution, reacting for 1h under magnetic stirring, and washing, filtering and drying to obtain the metallic aluminum loaded carbon black conductive filler.
(2) Preparation of metal aluminum loaded carbon black conductive filler-polyurethane elastic composite material layer
Adding 10g of polyurethane elastomer and 0.2g of metal aluminum loaded carbon black into tetrahydrofuran, mechanically stirring under the ultrasonic power condition of 1500W to fully dissolve the polyurethane elastomer, pouring the mixture into a mold, and then placing the mold in a fume hood until the solvent is completely volatilized to obtain the metal aluminum loaded carbon black-polyurethane elastomer composite layer.
(3) And (3) preparing a pure polyurethane elastomer composite material layer with the thickness of 2.5mm by adopting the same process flow in the step (2).
(4) Preparation of sandwich structure metal aluminum loaded carbon black-polyurethane elastomer composite material
And (3) laminating and pressing the composite material layer prepared in the step (2) and a pure polyurethane elastomer material with the thickness of 2.5mm to obtain the metal aluminum loaded carbon black-polyurethane elastomer composite material with the sandwich structure, wherein the middle layer is a pure polyurethane elastomer, and the surface layer is a conductive filler-polyurethane elastomer composite material.
(5) High pressure gas foaming
Cutting the sandwich structure aluminum-loaded carbon black-polyurethane elastomer composite material obtained in the step (4) into a regular shape, placing the regular shape in a high-pressure reaction kettle, heating, introducing pentane, saturating for 2 hours at 100 ℃ and 15MPa, then reducing the pressure to normal pressure at the pressure relief rate of 10MPa/s, taking out a foamed sample, and drying in a drying oven to finally obtain the sandwich structure polyurethane elastomer electromagnetic shielding composite foam.
Example 6
A preparation method of sandwich structure electromagnetic shielding composite foam comprises the following steps:
(1) preparation of highly conductive fillers
Slowly adding 1g of stainless steel fiber into 100mL of dilute sulfuric acid, mechanically stirring for 10h, repeatedly washing with distilled water, filtering to be neutral, adding the stainless steel fiber into a stannous chloride aqueous solution, mechanically stirring, adding the sensitized stainless steel fiber into 100mL of chemical iron plating solution (10 g/L of ferric sulfate and 5g/L of gentiobiose), slowly adding a sodium citrate aqueous solution, reacting for 10h under magnetic stirring, and washing, filtering and drying to obtain the metallic iron-loaded stainless steel fiber conductive filler.
(2) Preparation of metallic iron-loaded stainless steel fiber conductive filler-polyethylene composite layer
Adding 10g of polyethylene and 20g of metallic iron-loaded stainless steel fiber into dimethylbenzene, mechanically stirring under 2000W of ultrasonic power to fully dissolve the polyethylene, pouring the mixture into a mold, and then placing the mold in a fume hood until the solvent is completely volatilized to obtain the metallic iron-loaded stainless steel fiber-polyethylene composite layer.
(3) And (3) preparing a pure polyethylene composite material layer with the thickness of 1.5mm by adopting the same process flow in the step (2).
(4) Preparation of sandwich structure metal iron loaded stainless steel fiber-polyethylene composite material
And (3) laminating and pressing the composite material layer prepared in the step (2) and a pure polyurethane elastomer material with the thickness of 1.5mm to obtain the metallic iron loaded stainless steel fiber-polyethylene composite material with a sandwich structure, wherein the middle layer is made of pure polyethylene, and the surface layer is made of a conductive filler-polyethylene composite material.
(5) High pressure gas foaming
Cutting the sandwich structure iron-loaded stainless steel fiber-polyethylene composite material obtained in the step (4) into a regular shape, placing the regular shape in a high-pressure reaction kettle, heating, introducing dichloromethane, saturating at 60 ℃ and 5MPa for 1h, then reducing the pressure relief rate of 0.1MPa/s to the normal pressure, taking out a foamed sample, and drying in a drying oven to finally obtain the polyethylene electromagnetic shielding composite foam with the sandwich structure.
Analysis of results
Taking the embodiment 3 as an example, the cross section of the metallic silver-nickel loaded carbon fiber and the cross section of the sandwich structure polymer electromagnetic shielding composite foam are characterized by using a scanning electron microscope, and the results are respectively shown in fig. 1 and 2, it can be observed from fig. 1 that a layer of compact metallic nickel particles is deposited on the surface of the prepared carbon fiber, which is beneficial to improving the selective distribution of the metallic particles and improving the electromagnetic shielding performance of the composite foam. It can be seen from figure 2 that the skin of the syntactic foam is enriched with a significant amount of metallic nickel-loaded carbon fiber particles and the middle layer exhibits cells of larger diameter. This is because the pure polymer of the middle layer has a very low viscosity under high pressure gas, which is more favorable for the growth of bubbles after pressure relief, thereby forming a large number of large-size cells.
The sandwich-structured electromagnetic shielding composite foam prepared in example 5 was cut into a regular shape, and the electromagnetic shielding effectiveness of the foam was measured using an electromagnetic shielding tester, and fig. 3 is an electromagnetic shielding effectiveness of the composite foam at different intermediate layer thicknesses. Due to the effective loading of the metal on the surface of the filler particles, the conductive filler shows excellent conductivity, so that the composite foam is endowed with good electromagnetic shielding effectiveness (up to 49 dB). In addition, by comparing the electromagnetic shielding effectiveness of the composite foam with different intermediate layer thicknesses in the range of 8.2-12.4 GHz, it can be seen that the increase of the intermediate layer thickness effectively improves the shielding effectiveness of the composite foam, which is caused by multiple reflection and absorption of electromagnetic waves between the shielding surface layers.
While the present invention has been described in detail with reference to the embodiments, it should not be construed as limited by the scope of the present patent. Various modifications and changes may be made by those skilled in the art without inventive step within the scope of the appended claims.
Claims (10)
1. The preparation method of the sandwich structure electromagnetic shielding composite foam is characterized by comprising the following steps of:
s1: attaching conductive metal particles on the surface of the filler to obtain the high-conductivity filler;
s2: blending the high-conductivity filler with a polymer to prepare a conductive filler-polymer composite material;
s3: preparing a pure polymer material layer with the thickness of 0.1-5 mm;
s4: placing a pure polymer material layer in the middle, and placing the conductive filler-polymer composite material obtained in S2 on two sides for compounding to obtain a composite material with a sandwich structure;
s5: and (3) saturating the composite material with the sandwich structure obtained in the step (S4) for 1 min-48 h under the conditions of 30-280 ℃ and 0.5-50 MPa in a foaming gas environment, then decompressing to normal pressure at the rate of 0.1-30 MPa/S, and cooling to room temperature to obtain the composite material.
2. The method of claim 1, wherein the highly conductive filler is prepared by:
SS 1: coarsening and sensitizing filler particles in sequence;
SS 2: and adding the sensitized filler particles into chemical silver plating solution, chemical copper plating solution, chemical nickel plating solution, chemical aluminum plating solution, chemical iron plating solution or chemical tungsten plating solution according to the feed liquor ratio of 1g: 5-100 mL, then adding a reducing agent, reacting for 1 min-10h, and then washing and drying to obtain the composite filler.
3. The method of claim 2, wherein: the filler particles are non-metallic inorganic particles, carbon-based particles or metal fibers.
4. The production method according to claim 3, characterized in that: the non-metallic inorganic particles are at least one of nano silicon dioxide, calcium carbonate, glass fiber, quartz glass fiber, ceramic fiber, carbon fiber, asbestos fiber, basalt fiber, montmorillonite and barium sulfate; the carbon-based particles are at least one of carbon fibers, carbon black, carbon nanotubes, carbon quantum dots and football alkene; the metal fiber is at least one of stainless steel fiber and copper fiber.
5. The method of claim 1, wherein the conductive filler-polymer composite is prepared by: and blending the polymer and the conductive filler according to the mass ratio of 1: 2-50: 1 at 50-400 ℃ and 10-1000 rpm for 5min-10h to obtain the conductive filler.
6. The method of claim 1, wherein the conductive filler-polymer composite is prepared by: dissolving a polymer in a solvent, adding conductive filler which is 1/50-2 times of the polymer in mass, stirring to uniformly disperse the filler, and volatilizing the solvent to obtain the conductive polymer.
7. The method of claim 6, wherein: the solvent is ethanol, methanol, isopropanol, glycol, diethyl ether, acetone, hexane, cyclohexane, pentane, heptane, octane, aniline, butanone, chloroform, dimethylamine, carbon tetrachloride, N-heptanol, tetrahydrofuran, benzene, toluene, xylene, ethylbenzene, butyl acetate, chloroform, formic acid, dimethyl sulfoxide, chlorobenzene, dichlorobenzene, dichloromethane, trichloroethylene or N-methylpyrrolidone.
8. The production method according to claim 1, 5 or 6, characterized in that: the polymer is polyethylene, polypropylene, polycarbonate, polystyrene, polyvinyl chloride, polytetrafluoroethylene, polyamide, vinyl acetate copolymer, polyethylene terephthalate, polymethyl methacrylate, polycarbonate, polyurethane, polylactic acid, polyglycolic acid, polycaprolactone, polyvinyl alcohol, epoxy resin, urea resin, furan resin, melamine formaldehyde resin, silicone resin, polyarylate, acrylate, phenol resin, polyether ether ketone, polysulfone, polyphenylene sulfide, polyimide, styrene-butadiene rubber, isoprene rubber, butyl rubber, ethylene-propylene rubber, fluorine rubber, silicone rubber, thermoplastic polystyrene elastomer, thermoplastic polyolefin elastomer, thermoplastic copolyester elastomer, thermoplastic polyamide elastomer, or thermoplastic polyurethane elastomer.
9. The method of claim 1, wherein: the foaming gas is air, nitrogen, carbon dioxide, helium, argon, petroleum ether, methane, ethane, propane, butane, pentane, hexane, heptane, n-pentane, n-hexane, n-heptane, dichloromethane or trichlorofluoromethane.
10. The sandwich structure electromagnetic shielding composite foam prepared by the preparation method of any one of claims 1 to 9.
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