Broadband heat-conducting shielding coating material and preparation method of shielding material
By preparing a broadband thermally conductive shielding material comprising continuous conductive carbon fibers, conductive and thermally conductive powder, and magnetic metal powder, the problems of poor thermal conductivity, high density, poor corrosion resistance, and narrow shielding performance of existing electromagnetic shielding materials have been solved, achieving efficient and lightweight broadband electromagnetic shielding and thermal conductivity.
Patent Information
- Application Number
- CN202511363954.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-23
- Publication Date
- 2025-11-11
AI Technical Summary
Existing electromagnetic shielding materials have poor thermal conductivity, high density, poor temperature and corrosion resistance, low shielding effectiveness, and narrow shielding range, making it difficult to work effectively over a wide frequency range.
A broadband thermally conductive shielding material is prepared by coating or scraping low-cost continuous conductive carbon fiber, conductive and thermally conductive powder and magnetic metal powder, combined with metal mesh, and utilizing mechanisms such as eddy current and hysteresis loss to achieve efficient shielding and heat dissipation.
It achieves efficient electromagnetic shielding and thermal conductivity over a wide frequency range, reduces material thickness and weight, and improves the material's mechanical properties and corrosion resistance.
Smart Images
Figure CN120924034A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of composite materials and their products, and in particular to a shielding material and its preparation method. Background Technology
[0002] In recent years, the rapid development of electronic information technology has not only led to a dramatic increase in the number of wireless communication devices used, but also a significant increase in the frequency of electronic device usage. This has resulted in a rapid accumulation and increase in heat generated by electronic devices, as well as a large amount of electromagnetic interference and radiation frequency interference. This not only has irreversible effects on human health, but also interferes with the normal operation of electronic devices, and the large amount of heat also affects the lifespan of these devices. Therefore, there is an urgent need to develop materials with electrical and thermal conductivity as well as electromagnetic shielding functions to ensure that electronic devices operate normally without interference and to dissipate heat effectively, thus extending their lifespan.
[0003] Currently, the main electromagnetic shielding materials on the market primarily use metal sheets or metal shields made of copper, iron, steel, and alloys to block electromagnetic waves. However, these materials have high density, are prone to corrosion, and have limited adjustable shielding effectiveness. Furthermore, the shielding mechanism of metallic materials is mainly based on reflection, leaving electromagnetic pollution in the environment. Therefore, there is a need to develop a lightweight, ultra-thin, broadband, chemically resistant electromagnetic shielding material that primarily absorbs electromagnetic waves.
[0004] Carbon-based materials such as carbon black, carbon fiber, carbon nanotubes, and graphene are commonly used lightweight conductive and thermally conductive microwave absorbing materials. Among them, carbon fiber possesses properties such as high temperature resistance, friction resistance, electrical conductivity, thermal conductivity, and corrosion resistance. Compared to chopped carbon fibers, continuous carbon fibers not only possess the advantages of carbon-based materials but also easily form conductive pathways, resulting in superior shielding performance. Currently, most continuous carbon fiber shielding materials on the market, including nickel-plated, silver-plated, and copper-plated metallic carbon fiber shielding materials, have good thermal conductivity and excellent shielding performance, but their shielding is mostly limited to low-frequency and narrow-band ranges, restricting their application in the military field. To address this current challenge, this patent develops a broadband thermally conductive shielding material, which is of great significance. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a broadband thermally conductive shielding coating material and a method for preparing the shielding material, solving the technical problems of poor thermal conductivity, high density, poor temperature and corrosion resistance, low shielding effectiveness, and poor absorption effectiveness of existing electromagnetic shielding materials.
[0006] The objective of this invention is achieved as follows: a broadband thermally conductive shielding coating material, composed of the following components in parts by weight: 100 parts resin; 3-26 parts of conductive and thermally conductive powder; 30-50 parts of magnetic metal powder; 0.2-1 part of silane coupling agent.
[0007] As a further limitation of the broadband thermally conductive shielding coating material described in this invention, the resin is one or more of epoxy resin, phenolic resin, polyimide, cyanate ester, silicone resin, bismaleimide resin, etc.
[0008] As a further definition of the broadband thermally conductive shielding coating material described in this invention, the conductive and thermally conductive powder is one or more of the following one-dimensional, two-dimensional or three-dimensional fillers: conductive and thermally conductive graphene, sheet graphene or fibrous graphene, graphene aerogel, pitch-based carbon fiber, nickel-plated pitch-based carbon fiber, nickel-coated graphite powder, etc.
[0009] As a further limitation of the broadband thermally conductive shielding coating material described in this invention, the magnetic metal powder is one or more of carbonyl iron powder, ferrite, and alloy powder.
[0010] As a further limitation of the broadband thermally conductive shielding coating material described in this invention, the silane coupling agent is one or more of tetraethyl orthosilicate, KH550, KH560, and KH570.
[0011] A method for preparing a broadband thermally conductive shielding material, using the above-mentioned coating material, includes the following steps: Step 1) Prepare the raw materials according to the above composition. Mix the resin, conductive and thermally conductive powder and magnetic metal powder evenly with a mixer. The mixing speed and mixing temperature need to be determined according to the resin viscosity. Add silane coupling agent during the mixing process. Step 2) Prepare continuous carbon fiber; Step 3) Prepare resin-coated carbon fiber prepreg by coating or blade coating, with the resin content accounting for 38-60% of the weight of the resin-coated carbon fiber prepreg; Step 4) After laying the layers in the direction of layup, prepare the laminate and lay 1-3 layers of metal mesh on the outermost layer; Step 5) Finally, the resin is cured by autoclave or molding process. The curing temperature and curing procedure are determined according to the resin.
[0012] As a further limitation of the preparation method of the broadband thermally conductive shielding material described in this invention, the continuous carbon fiber is one or more composites of ordinary carbon fiber, nickel-plated carbon fiber, silver-plated carbon fiber, copper-plated carbon fiber, and aluminum-plated carbon fiber.
[0013] As a further limitation of the preparation method of the broadband thermally conductive shielding material described in this invention, the metal mesh is one or more of copper mesh, copper mesh, and nickel mesh, with a mesh size of 200-300 mesh.
[0014] Conductive and thermally conductive powder: Due to its high conductivity, when the frequency of incident electromagnetic waves is high, the eddy currents generated within the highly conductive material cancel out the incoming electromagnetic waves, thus achieving a shielding effect. Because of the high-frequency skin effect, the eddy currents only flow in a thin layer on the surface of the shielding material; therefore, the thickness of the shielding material can be reduced, and the product weight can be decreased. By adding conductive and thermally conductive powder, high-efficiency shielding and heat dissipation at high frequencies can be achieved, while reducing product thickness and weight.
[0015] Magnetic metal powder: Due to its high permeability, magnetic metal powder is used to create a low magnetic reluctance path when the frequency of the incident electromagnetic wave is low. Higher permeability and greater thickness result in lower magnetic reluctance and better magnetic field shielding. High-efficiency shielding at low frequencies can be achieved by adding magnetic metal powder.
[0016] The synergistic effect of conductive and thermally conductive powder and magnetic metal powder enables the material to achieve high shielding efficiency at both low and high frequencies, i.e., a wider frequency shielding efficiency.
[0017] Silane coupling agent: By adding silane coupling agent, the conductive and thermally conductive powder and magnetic metal powder are more evenly dispersed in the resin matrix, which enhances the interfacial bonding force between the filler and the matrix and improves the mechanical properties of the shielding material.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention primarily utilizes low-cost continuous conductive carbon fibers, combined with conductive and thermally conductive powders, magnetic metal powders, and a metal mesh, to prepare a broadband thermally conductive shielding material. The continuous conductive carbon fibers are not only low-cost but also enhance the mechanical and shielding properties of the resin material. The conductive and thermally conductive powders further enhance the material's shielding and thermal conductivity. The magnetic metal powders convert electromagnetic waves into other forms of energy through hysteresis loss and eddy current loss, exhibiting strong shielding absorption efficiency at low frequencies. The metal mesh has high electron mobility, better thermal and electrical conductivity, and also possesses corrosion and high-temperature resistance. This invention solves the technical problems of existing electromagnetic shielding materials, such as poor thermal conductivity, high density, poor temperature and corrosion resistance, low shielding effectiveness, and narrow shielding range. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.
[0020] Figure 1 This is a schematic diagram of the shielded room method measurement in this invention. Detailed Implementation
[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0022] Example 1 A broadband thermally conductive shielding coating material is composed of the following components in parts by weight: 100 parts of cyanate ester, 22 parts of pitch-based carbon fiber (2-3μm), 30 parts of ferrite powder (8-16μm), and 0.2 parts of tetraethyl orthosilicate.
[0023] A method for preparing a broadband thermally conductive shielding material, using the above-mentioned coating material, includes the following steps: Step 1) Prepare the raw materials according to the above composition. Mix 100 parts of cyanate ester, 22 parts of pitch-based carbon fiber 2-3μm, and 30 parts of ferrite powder 8-16μm evenly in a mixer. The mixing speed and mixing temperature need to be determined according to the resin viscosity. Add 0.2 parts of tetraethyl orthosilicate during the mixing process. Step 2) Prepare ordinary carbon fiber; Step 3) Prepare resin-coated carbon fiber prepreg by coating or blade coating. The resin content accounts for 38% of the weight of the resin-coated carbon fiber prepreg, and the areal density of the prepreg is 500 g / m³. 2 ; Step 4) After laying the layers according to the layup direction, prepare the laminate and lay a layer of metal mesh on the outermost layer, specifically using 250 mesh copper mesh; Step 5) Finally, the resin is cured by autoclave or molding process. The curing temperature and curing procedure are determined according to the resin.
[0024] Example 2 A broadband thermally conductive shielding coating material is composed of the following components in parts by weight: 100 parts epoxy resin, 3 parts graphene (5-15μm), 50 parts carbonyl iron powder (8-16μm), and 0.6 parts silane coupling agent KH550.
[0025] A method for preparing a broadband thermally conductive shielding material, using the above-mentioned coating material, includes the following steps: Step 1) Prepare the raw materials according to the above composition. Mix 100 parts of epoxy resin, 3 parts of graphene (5-15μm), and 50 parts of carbonyl iron powder (8-16μm) evenly with a mixer. The mixing speed and temperature need to be determined according to the resin viscosity. Add 0.6 parts of silane coupling agent KH550 during the mixing process. Step 2) Prepare nickel-plated carbon fiber; Step 3) Prepare resin-coated carbon fiber prepreg by coating or blade coating. The resin content accounts for 52% of the weight of the resin-coated carbon fiber prepreg, and the areal density of the prepreg is 600 g / m³. 2 ; Step 4) After laying the layers in the direction of layup, prepare the laminate and lay two layers of 300-mesh nickel mesh on the outermost layer; Step 5) Finally, the resin is cured by autoclave or molding process. The curing temperature and curing procedure are determined according to the resin.
[0026] Example 3 A broadband thermally conductive shielding coating material is composed of the following components in parts by weight: 100 parts of bismaleimide resin, 26 parts of nickel-coated graphite (25μm), 35 parts of iron-nickel alloy powder (4-10μm), and 1 part of silane coupling agent KH570.
[0027] A method for preparing a broadband thermally conductive shielding material, using the above-mentioned coating material, includes the following steps: Step 1) Prepare the raw materials according to the above composition. Mix 100 parts of bismaleimide resin, 26 parts of nickel-coated graphite (25μm), and 35 parts of iron-nickel alloy powder (4-10μm) evenly with a mixer. The mixing speed and temperature need to be determined according to the resin viscosity. Add 1 part of silane coupling agent KH570 during the mixing process. Step 2) Prepare silver-plated and nickel-plated carbon fibers, 50% each; Step 3) Prepare resin-coated carbon fiber prepreg by coating or blade coating. The resin content accounts for 60% of the weight of the resin-coated carbon fiber prepreg, and the areal density of the prepreg is 800 g / m³. 2 ; Step 4) After laying the layers according to the layup direction, prepare the laminate and lay a layer of 300-mesh copper mesh on the outermost layer; Step 5) Finally, the resin is cured by autoclave or molding process. The curing temperature and curing procedure are determined according to the resin.
[0028] Please refer to the table below for specific parameters:
[0029] The shielding materials prepared in the three embodiments were tested according to GJB 8820-2015 "Method for Measuring the Shielding Effectiveness of Electromagnetic Shielding Materials". The shielding effectiveness of the materials was measured using the shielding chamber method. The samples were flat plate structures with dimensions not less than 600*600mm. The samples were placed in... Figure 1 By changing the transmitting and receiving antennas to the appropriate frequency bands, the shielding effectiveness of different frequency bands can be obtained.
[0030] The test results are shown in the table below:
[0031] In summary, this invention primarily utilizes low-cost continuous conductive carbon fibers, combined with conductive and thermally conductive powders, magnetic metal powders, and a metal mesh, to prepare a broadband thermally conductive shielding material. The continuous conductive carbon fibers are not only low-cost but also enhance the mechanical and shielding properties of the resin material. The conductive and thermally conductive powders further enhance the material's shielding and thermal conductivity. The magnetic metal powders convert electromagnetic waves into other forms of energy through hysteresis loss and eddy current loss, exhibiting strong shielding absorption efficiency at low frequencies. The metal mesh has high electron mobility, better thermal and electrical conductivity, and also possesses corrosion and high-temperature resistance. This invention solves the technical problems of existing electromagnetic shielding materials, such as poor thermal conductivity, high density, poor temperature and corrosion resistance, low shielding effectiveness, and narrow shielding range.
[0032] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.
Claims
1. A broadband thermally conductive shielding coating material, characterized in that, It consists of the following components in parts by weight: 100 parts resin; 3-26 parts of conductive and thermally conductive powder; 30-50 parts of magnetic metal powder; 0.2-1 part of silane coupling agent.
2. A broadband thermally conductive shielding coating material according to claim 1 or 2, characterized in that, The resin is one or more of epoxy resin, phenolic resin, polyimide, cyanate ester, silicone resin, bismaleimide resin, etc.
3. A broadband thermally conductive shielding coating material according to claim 1 or 2, characterized in that, The conductive and thermally conductive powder is one or more of the following: conductive and thermally conductive graphene, sheet graphene or fibrous graphene, graphene aerogel, pitch-based carbon fiber, nickel-plated pitch-based carbon fiber, nickel-coated graphite powder, etc., which are one-dimensional, two-dimensional or three-dimensional fillers.
4. A broadband thermally conductive shielding coating material according to claim 1 or 2, characterized in that, The magnetic metal powder is one or more of carbonyl iron powder, ferrite, and alloy powder.
5. A broadband thermally conductive shielding coating material according to claim 1 or 2, characterized in that, The silane coupling agent is one or more of tetraethyl orthosilicate, KH550, and KH570.
6. A method for preparing a broadband thermally conductive shielding material, using the coating material as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1) Prepare the raw materials according to the above composition. Mix the resin, conductive and thermally conductive powder and magnetic metal powder evenly with a mixer. The mixing speed and mixing temperature need to be determined according to the resin viscosity. Add silane coupling agent during the mixing process. Step 2) Prepare continuous carbon fiber; Step 3) Prepare resin-coated carbon fiber prepreg by coating or blade coating, with the resin content accounting for 38-60% of the weight of the resin-coated carbon fiber prepreg; Step 4) After laying the layers in the direction of layup, prepare the laminate and lay 1-3 layers of metal mesh on the outermost layer; Step 5) Finally, the resin is cured by autoclave or molding process. The curing temperature and curing procedure are determined according to the resin.
7. The method for preparing a broadband thermally conductive shielding material according to claim 6, characterized in that, The continuous carbon fiber is one or more composites of ordinary carbon fiber, nickel-plated carbon fiber, silver-plated carbon fiber, copper-plated carbon fiber, and aluminum-plated carbon fiber.
8. The method for preparing a broadband thermally conductive shielding material according to claim 6, characterized in that, The metal mesh is one or more of copper mesh, copper mesh, and nickel mesh, with a mesh count of 200-300 mesh.