CN112804868B - Preparation process of electromagnetic shielding composite material - Google Patents

Abstract

The invention relates to a preparation process of an electromagnetic shielding composite material, which comprises the following steps: crushing the foam metal with the through holes into foam metal particles with the particle size of 0.5-5 mm, banburying the metal particles and plastic particles into a cluster to obtain a composite material, and rolling the composite material into a sheet to obtain the electromagnetic shielding composite material. This application forms the structure of evenly nesting each other between metal and the plastics through the step of banburying jointly with the plastic particle with the foam metal that has the through-hole and rolling, on the one hand can show the bonding strength who has improved plastics and metal through this crisscross structure, and on the other hand has realized the shielding to the electromagnetism of plastics and foam metal composite sheet after the rolling, has increased combined material's heat conduction effect.

Description

Preparation process of electromagnetic shielding composite material

Technical Field

The invention belongs to the field of materials, and particularly relates to a preparation process of an electromagnetic shielding composite material.

Background

With the rapid development of the electronic industry, the number of various civil and military electronic products has increased dramatically, and electromagnetic interference has become a new social public nuisance. Plastics are used as housing materials for electronic products because of their advantages of light weight, corrosion resistance, low cost, good moldability, etc. However, common plastics are insulators, on one hand, electrostatic charges are easy to accumulate, and fires and explosions are easy to cause in inflammable and explosive places, and on the other hand, the plastics are almost transparent to electromagnetic waves, cannot absorb and reflect, have no shielding capability and do not have the performance of resisting electromagnetic interference. Therefore, the research on the novel shielding composite material with the wave absorbing function, good conductivity and good processing performance can provide good means and guarantee for military affairs, communication, confidentiality, computer system engineering, electronic control engineering, bioengineering and high-tech electromagnetic compatibility, and the method has great practical significance for social life and national defense construction.

The potential hazard existing in electromagnetic radiation is discussed and solved from the technical aspect, and the method mainly comprises two aspects: (1) Optimizing circuit design and wiring separation, including circuit board design with grounding wires; and (2) reducing electromagnetic interference materials by using electromagnetic shielding materials.

The design of the optimized circuit has the defects of complex process and time-consuming processing technology, so that independent research and development of the electromagnetic wave shielding material are urgently needed, and the shielding material industry is formed as soon as possible.

The shielding materials commonly used at present mainly include: (1) The plastic substrate is externally sprayed with conductive coating materials, including metal coatings, carbon material coatings, composite material coatings and the like, but the thin coatings can only have a shielding function on electromagnetic waves with certain frequency, and meanwhile, the strength and the heat conduction performance of the plastic substrate are not improved; (2) The filled composite electromagnetic shielding plastic is prepared by mixing and granulating conductive filler and synthetic resin, and adopting methods such as injection molding, extrusion molding or compression molding, and the like, and the filled composite electromagnetic shielding plastic has certain strength due to the addition of the conductive filler, but the filler and the resin have poor bonding force to cause large brittleness, and the filled composite electromagnetic shielding plastic is easy to crack in application; (3) Other electromagnetic shielding materials, including filled electromagnetic shielding rubber, intrinsic conductive polymer, conductive fabric, etc., have low strength and poor moldability, and only have shielding effect on electromagnetic waves of certain frequencies.

At present, the electromagnetic shielding plastic will be developed to be multi-layered, multifunctional, wide, thin, strong, light, etc., and the above problems are technical problems to be solved in the art.

Disclosure of Invention

The invention provides a preparation process of an electromagnetic shielding composite material for solving the technical problems.

The technical scheme for solving the technical problems is as follows: a preparation process of an electromagnetic shielding composite material comprises the following steps:

the foam metal with the through holes is crushed into foam metal particles with the particle size of 0.5-5 mm,

banburying the metal particles and plastic particles into a mass to obtain the composite material

And rolling the composite material into a sheet to obtain the electromagnetic shielding composite material. .

The electromagnetic shielding composite material and the preparation process disclosed by the application have the beneficial effects that: the step of banburying and rolling together through the foamed metal that will have the through-hole and plastic pellet forms the structure of nesting each other between metal and the plastics uniformly, on the one hand can show the bonding strength who has improved plastics and metal through this crisscross structure, and on the other hand has realized the shielding to the electromagnetism of plastics and foamed metal composite sheet after the rolling, has increased combined material's heat conduction effect.

Further, the step of banburying agglomeration is performed in an internal mixer.

Further, the banburying temperature is 100-500 ℃, and the banburying step is carried out in an inert atmosphere.

Further, the rolling step is performed in a shuttle mill.

Further, the foam metal is a foam metal with reticular through holes.

Furthermore, the diameter of the through hole in the foam metal is 10 mu-2000 mu, and the porosity of the foam metal is 30-98%.

Further, the foam metal is one or more of foam nickel, foam copper, foam silver, foam titanium and foam aluminum.

Further, the foamed metal accounts for 20 to 70% by weight of the composite material.

Further, the plastic particles are one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyamide, polyformaldehyde, polycarbonate, polyphenyl ether, polysulfone and rubber.

Further, the thickness of the electromagnetic shielding composite material is 0.1-100 mm.

Drawings

FIG. 1 is a scanning electron micrograph of the foamed nickel of example 1;

FIG. 2 is a scanning electron micrograph of the nickel foam and polycarbonate electromagnetic shielding composite material of example 1;

FIG. 3 is a scanning electron micrograph showing an enlarged cross section of the nickel foam of example 1.

Detailed Description

The principles and features of this application are described below in conjunction with the drawings and the embodiments, which are set forth to illustrate the application and not to limit the scope of the application.

The following discloses many different embodiments or examples for implementing the subject technology described. While specific examples of one or more arrangements of features are described below to simplify the disclosure, the examples should not be construed as limiting the present disclosure, and a first feature described later in the specification in conjunction with a second feature can include embodiments that are directly related, can also include embodiments that form additional features, and further can include embodiments in which one or more additional intervening features are used to indirectly connect or combine the first and second features to each other so that the first and second features may not be directly related.

Example 1

A preparation process of a foamed nickel sheet and polycarbonate electromagnetic shielding composite material.

An electron microscope scanning photograph of a foamed nickel sheet having a thickness of 1mm and a pore size of 30 μ, which had been shown in fig. 1, and a scanning electron microscope photograph of an enlarged cross section, which had been shown in fig. 3, showed that the through-holes had a net shape.

Crushing the mixture into particles with the particle size of 1mm, and then heating and banburying the particles and polycarbonate particles in a high-temperature banbury mixer to form a cluster, so as to obtain the composite material, wherein the mass ratio of the foam nickel flake powder is 40%, and the mass ratio of the polycarbonate particles is 60%.

In order to ensure that the polycarbonate particles are softened during banburying, and penetrate and fill the pores of the foamed nickel metal, the banburying agglomeration temperature is controlled to be 280 ℃, and in order to prevent the foamed nickel particles and the polycarbonate particles from being oxidized during high-temperature banburying, argon is added into a banburying cavity for protection.

Sending the internally mixed and agglomerated foam nickel and polycarbonate composite material into a reciprocating rolling mill, arranging heating and heat-insulating cavities at two ends of the reciprocating rolling mill, controlling the temperature of the heat-insulating cavities and the rolling temperature to be 260-300 ℃, gradually reducing the clearance between an upper roller and a lower roller to roll the sheet in a reciprocating manner, and finally rolling the foam nickel and polycarbonate composite material into a sheet with the thickness of 0.5mm, wherein an electron microscope scanning photo of the sheet is shown in figure 2, so that plastic particles are uniformly nested with the foam nickel.

The test results of the sheet show that the highest shielding effectiveness of the rolled composite material can reach 50dB under the condition of 800MHz frequency.

Example 2

A preparation process of a foam copper and polyformaldehyde electromagnetic shielding composite material.

The foamed copper sheet with the thickness of 1.5mm and the pore size of 50 mu and provided with through holes is crushed into particles with the particle size of 1.5mm, and then the particles and polyformaldehyde particles are heated and banburied in a high-temperature banbury mixer to form a mass ratio, wherein the foamed copper particles account for 60% by mass, and the polyformaldehyde particles account for 40% by mass.

In order to ensure that the polyformaldehyde particles are softened during banburying and permeate and fill pores of the foamed copper metal, the banburying agglomeration temperature is controlled to be 200 ℃, and in order to prevent the foamed copper particles and the POM-polyformaldehyde particles from being oxidized during high-temperature banburying, argon is added into a banburying cavity for protection.

Sending the foamed copper and polyformaldehyde composite material which is internally mixed into a cluster into a reciprocating rolling mill, arranging heating and heat-insulating cavities at two ends of the reciprocating rolling mill, controlling the temperature of the heat-insulating cavities and the rolling temperature to be 180-220 ℃, gradually reducing the clearance between an upper roller and a lower roller to roll sheets in a reciprocating manner, and finally rolling the foamed copper and polyformaldehyde composite material into sheets with the thickness of 1 mm.

The sheet is tested, and the electromagnetic shielding function of the rolled composite material can reach 60dB at the highest shielding efficiency under the condition of the frequency of 1000 MHz.

Example 3

A preparation process of an electromagnetic shielding composite material of foamed silver and polyphenyl ether.

The foamed silver sheet with the thickness of 2mm and the aperture size of 100 mu is crushed into particles with the particle size of 2mm, and then the particles and polyphenyl ether are heated and banburied in a high-temperature banbury mixer to form a cluster, wherein the mass ratio of the foamed silver particles is 70 percent, and the mass ratio of the polyphenyl ether particles is 30 percent.

In order to ensure that the polyphenyl ether particles are softened during banburying and permeate and fill the pores of the foamed silver metal, the banburying agglomeration temperature is controlled to be 320 ℃, and in order to prevent the foamed silver particles and the polyphenyl ether particles from being oxidized during high-temperature banburying, argon is added into a banburying cavity for protection.

Sending the internally-mixed and agglomerated foamed silver and polyphenyl ether composite material into a reciprocating rolling mill, arranging heating and heat-insulating cavities at two ends of the reciprocating rolling mill, controlling the temperature of the heat-insulating cavities and the rolling temperature to be 300-340 ℃, gradually reducing the clearance between an upper roller and a lower roller to roll the sheet material in a reciprocating manner, and finally rolling the foamed silver and polyphenyl ether composite material into a sheet material with the thickness of 2 mm.

The sheet is tested, and the electromagnetic shielding function of the rolled composite material can reach 70dB at the highest shielding effectiveness under the frequency of 1200 MHz.

In the description of this specification, "plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.

In the description of the present specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

The terms used in the present specification are those general terms currently widely used in the art in consideration of functions related to the present disclosure, but they may be changed according to the intention of a person having ordinary skill in the art, precedent, or new technology in the art. Also, specific terms may be selected by the applicant, and in this case, their detailed meanings will be described in the detailed description of the present disclosure. Therefore, the terms used in the specification should not be construed as simple names but based on the meanings of the terms and the overall description of the present disclosure.

Flowcharts or text are used in this specification to illustrate operational steps performed in accordance with embodiments of the present application. It should be understood that the operational steps in the embodiments of the present application are not necessarily performed in the exact order recited. Rather, the various steps may be processed in reverse order or simultaneously, as desired. Meanwhile, other operations may be added to the processes, or a certain step or several steps of operations may be removed from the processes.

The above description is only a preferred embodiment of the present application and should not be taken as limiting the present application, and any modifications, equivalents, improvements and the like that are made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims (1)

1. The preparation process of the electromagnetic shielding composite material is characterized by comprising the following steps of:

crushing the foamed silver sheet with the thickness of 2mm and the aperture size of 100 mu and through holes into particles with the particle size of 2mm, and then heating and banburying the particles and polyphenyl ether in a high-temperature banbury mixer to form a cluster, wherein the mass ratio of the foamed silver particles is 70 percent, and the mass ratio of the polyphenyl ether particles is 30 percent;

controlling the banburying agglomeration temperature to be 320 ℃, and adding argon for protection;

sending the internally-mixed and agglomerated foamed silver and polyphenyl ether composite material into a reciprocating rolling mill, arranging heating and heat-insulating cavities at two ends of the reciprocating rolling mill, controlling the temperature of the heat-insulating cavities and the rolling temperature to be 300-340 ℃, gradually reducing the clearance between an upper roller and a lower roller to roll the sheet material in a reciprocating manner, and finally rolling the foamed silver and polyphenyl ether composite material into a sheet material with the thickness of 2 mm.

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