CN102964899B - Low-reflectivity high-efficiency electromagnetic shielding material - Google Patents
Low-reflectivity high-efficiency electromagnetic shielding material Download PDFInfo
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- CN102964899B CN102964899B CN201210453671.4A CN201210453671A CN102964899B CN 102964899 B CN102964899 B CN 102964899B CN 201210453671 A CN201210453671 A CN 201210453671A CN 102964899 B CN102964899 B CN 102964899B
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Abstract
The invention discloses a low-reflectivity high-efficiency electromagnetic shielding material and belongs to the technical field of electromagnetic shielding materials. The low-reflectivity high-efficiency electromagnetic shielding material comprises a composite electromagnetic shielding component consisting of the materials with different electromagnetic characteristics, wherein the composite electromagnetic shielding component consists of metal powder with the relative electric conductivity equal to or larger than 0.02, ferromagnetic material powder with the relative electric conductivity equal to or larger than 1, and a high polymer dielectric material, the volume ratio of the metal powder is within 70-97%, the volume ratio of the ferromagnetic material powder is within 1-29%, and the volume ratio of the high polymer dielectric material is within 1-29%. According to the low-reflectivity high-efficiency electromagnetic shielding material disclosed by the invention, on the basis of ensuring a high electromagnetic shielding efficiency through a composition effect, the reflection to electromagnetic waves is reduced and the absorption of the electromagnetic waves is increased so that the purpose of reducing secondary pollution is reached; and according to the Chinese military standard GJB6190-2008, within an electromagnetic wave frequency range of 30-1500 MHz, the electromagnetic shielding efficiency can reach more than 60 dB (B level).
Description
Technical field
The invention belongs to technical field of electromagnetic shielding, the functional material of particularly administering for electromagnetic radiation environment.
Background technology
A large amount of uses along with electronics, cause electromagnetic radiation, and the space-pollution of this radiation formation has caused very big harm to the healthy of the safe true(-)running of electronics and people, so the improvement of electromagnetic radiation is become more and more important.Electromagnetic shielding material is effectively to administer electromagnetic harm, the important means of shielding electromagnetic interference.
The method of traditional electrical magnetic shielding is to adopt sheet metal, but sheet metal exists Heavy Weight, is difficult to the inherent defects such as installation and sealing, and its application is restricted.Electromagnetic shielding due to sheet metal mainly relies on electromagnetic reflection simultaneously, and reflection electromagnetic wave can cause secondary pollution, therefore neither a kind of eco-friendly electromagnetic shielding material.Development of new electromagnetic shielding material is the focus of studying at present.Disclosed Chinese patent 03121536.X on September 10th, 2003 " organic/inorganic composite electromagnetic wave absorbent curtain coating material ", has proposed organic/inorganic composite electromagnetic and has inhaled the formation pattern that involves shielding coating.This method need to adopt the technological process of more complicated that conductive polymers is coated on outside soft magnetic metal powder, forms a kind of compound structure.The difficulty of this method is that coated thickness and degree of uniformity are difficult to control, and production process is difficult to realize; And after polymer overmold, can cause specific conductivity to reduce, and be difficult to obtain high-efficiency electromagnetic shielding properties.Chinese patent 1597308A " a kind of preparation method of organic/inorganic multilayer hybrid electromagnetic wave shielding material " is disclosed on March 23rd, 2005, the simple preparation method of direct mixing has wherein been proposed, but need to utilize laminated coating to carry out compound raising absorbs and effectiveness of shielding, this mode can increase coat-thickness, thereby causes the bonding force variation of coating and matrix and cost to improve.And for this kind of mode of production, in patent, only proposed to utilize Fe, Ni and tri-kinds of pure metal powders of Co and its powdered alloy, and do not consider complex effect and the low reflection characteristic of different electromagnetic property materials, be also difficult to obtain high-efficiency shielding usefulness.
Therefore in above-mentioned two patented technologies, obviously deposit problem both ways, one, the mode of production complicated difficult of conductive polymers clad metal powder is to control; Its two, mainly adopted pure metal powder Fe, Ni and Co and alloy thereof, be difficult to obtain the over-all properties of high conductivity and high magnetic permeability, thereby can not obtain thering is high-efficiency shielding usefulness, and there is the high characteristic absorbing of low reflection simultaneously.Adopt the electromagnetic shielding material of pure metal screening component can only obtain single electromagnetic performance, for trying to achieve high shield effectiveness, often need high reflection loss, and reflection loss will cause larger secondary pollution.
Summary of the invention
1. the technical problem that invention will solve
The object of the invention is to overcome the shortcoming that the single conductive filler material of available technology adopting is difficult to obtain the effectiveness of shielding of high-efficient wide-frequency, a kind of high-efficiency electromagnetic shielding material of low reflection is provided, it is target that the environmental friendliness high-efficiency electromagnetic shielding material of low reflection (low secondary pollution) is take in the present invention, propose to utilize the complex effect between the material with different electromagnetic propertys, with the metal powder material of high conductivity to electromagnetic reflection, the ferromagnetic material of high magnetic permeability to electromagnetic eddy current decay and polymer dielectric material to electromagnetic dielectric loss, realization shields electromagnetic high-efficiency electromagnetic.Its key problem in technology is to have selected different materials according to the electromagnetic property of material, comparative analysis by experiment, determined the composition proportion scheme of optimizing, utilize the complex effect of different electromagnetic property materials, can reduce the specific conductivity of material and increase magnetic loss and dielectric loss, thereby guarantee do not reducing on the basis of electromagnet shield effect, reduce electromagnetic reflection, reduce secondary pollution, made eco-friendly high-efficiency electromagnetic shielding material.
2. technical scheme
For achieving the above object, technical scheme provided by the invention is:
The high-efficiency electromagnetic shielding material of a kind of low reflection of the present invention, comprises the composite electromagnetic screen component that the material by different electromagnetic propertys forms.Comprising metal-powder, the ferromagnetic material powder with high magnetic permeability characteristic of relative magnetic permeability >=1 and the polymer dielectric materials with high dielectric loss characteristics such as the nickel with high conductivity, silver or copper of relative conductivity >=0.02, as: electrically conductive polyaniline.Above-mentioned materials can be obtained with different ratio mixing the serial electromagnetic shielding material with different electromagnetic shielding characteristics.Select different material composition proportionings, can make electromagnetic shielding material obtain different specific conductivity and magnetic permeability and specific inductivity, thereby can realize in different frequency ranges high-efficiency electromagnetic shielding, and can pass through adjusting component, the relative proportion of change to electromagnetic reflection and absorption, reaches the object of controlling electromagnet shield effect and reducing secondary pollution.The composition proportion of different electromagnetic propertys can require to combine according to electromagnetic shielding, to reach optimum cost performance.
In order to guarantee to have enough electromagnet shield effects, the volume ratio of high conductivity metal powder should be between 70%-97%; The volume ratio of the ferromagnetic material powder of high magnetic permeability is between 1%-29%; The volume ratio of polymer dielectric material is between 1%-29%.
In order to reach the requirement that is formed into spot net and the usage quantity that reduces material, the diameter of the high conductivity metal powder adopting in composite electromagnetic screen component is at 2-20 micron; The diameter of the ferromagnetic material powder of the high magnetic permeability adopting is at 2-20 micron; The polymer dielectric material adopting can adopt liquid or polyaniline powder, and the diameter of powder is at 1-50 micron.
In the preparation process of electromagnetic shielding material, the composite electromagnetic screen component consisting of the material of different electromagnetic propertys is mixed with into electromagnetic screen coating with body material.Body material is comprised of resin or paint.Wherein the volume fraction of composite electromagnetic screen component is 5%-40%, and body material volume fraction is 60%-95%.
First the preparation method of electromagnetic shielding material of the present invention mixes the powder of the compound different electromagnetic propertys of needs ratio as requested, then carry out ultrasonic dispersion and homogenizing, obtain adding body material to stir after uniform mixed powder, put into ball-grinding machine and carry out ball milling, the time of ball milling is greater than 20 minutes, obtains electromagnetic shielding material.The performance that the present invention adopts that the processing parameter of optimization mixes, stirring and ball milling are obtained requirement, the preparation method of this composite electromagnetic shield materials is only by the simple and mechanical complex effect that has been obtained by mixing of various materials, single-layer coating can be realized high-efficiency electromagnetic shielding, have technique simple, be easy to control and the advantage such as easy-to-use.
3. beneficial effect
Adopt technical scheme provided by the invention, compare with existing known technology, there is following unusual effect:
(1) high-efficiency broadband: test in strict accordance with the GJB GJB 6190-2008 of the People's Republic of China (PRC) " electromagnetic shielding material effectiveness of shielding measuring method ", test frequency scope (30-1500MHz) in GB regulation all reaches 70-100dB, for B level product, except industry and the application of civil high-efficient electromagnetic shielding, can be used for aerospace and national defense applications;
(2) low secondary pollution: guaranteeing that by complex effect on the basis of high-efficiency electromagnetic shielding, minimizing increases electromagnetic absorption electromagnetic reflection, reaches the target that reduces secondary pollution; Under having compared with the condition of high square resistance (impedance of unit surface), obtain excellent electromagnet shield effect;
(3) lightweight, low cost, pollution-free: by optimizing components and production technology optimization, do not adopt silver to wait precious metal raw material and obtain high-efficiency electromagnetic effectiveness of shielding; And guaranteeing, on the basis of electromagnet shield effect, to have reduced the content of metal component, reached the object of lightweight; Pollution-free in production and application process;
(4) easy to use, suitability is strong: electromagnetic shielding material of the present invention is a kind of functional paint, and coating can be coated on the base materials such as the wall, timber of most of plastics, buildings, realizes the object of electromagnetic shielding.
Embodiment
For further understanding content of the present invention, the present invention is described in detail in conjunction with the embodiments.
embodiment 1
In the present embodiment, the metal-powder of relative conductivity >=0.02 is selected metal nickel powder, and the ferromagnetic material powder of relative magnetic permeability >=1 is selected ferrocobalt powder, polymer dielectric material selection electrically conductive polyaniline powder.Select the metal nickel powder of 2 micron diameters, the ferrocobalt powder of 3 micron diameters and the electrically conductive polyaniline powder of 2 microns, according to metal nickel powder, accounting for composite electromagnetic screen component volume ratio is 70%, ferrocobalt powder account for composite electromagnetic screen component volume ratio be 17% and electrically conductive polyaniline account for the ratio that composite electromagnetic screen component volume ratio is 13% and carry out compound.After above-mentioned powder is mixed in proportion, utilize ultrasonic wave separating apparatus to disperse 20 minutes, obtain uniform composite electromagnetic screen component.Adding acrylic resin is body material.The volume ratio of composite electromagnetic screen component and acrylic resin is respectively 15.5% and 84.5%.Mixed colloid is put into planetary ball mill ball milling and within 1 hour, obtain electromagnetic screen coating of the present invention.According to the GJB GJB 6190-2008 of the People's Republic of China (PRC), it is for testing effectiveness of shielding on the resin substrate of 115 millimeters that shielding coating is sprayed on to diameter with spraying equipment.This sample its effectiveness of shielding in the range of frequency of 30MHz-1500MHz is 70-85dB after tested, and the loss of intensity of absorption portion is more than 25% as calculated.And the electromagnet shield effect of like product is in the market completely by electromagnetic reflection is realized, and has larger secondary pollution.
embodiment 2
In the present embodiment, the metal-powder of relative conductivity >=0.02 is selected powder of stainless steel, and the ferromagnetic material powder of relative magnetic permeability >=1 is selected iron nickel by powder, polymer dielectric material selection electrically conductive polyaniline powder.Select the powder of stainless steel of 10 micron diameters, the electrically conductive polyaniline powder through doped hydrochloride of the iron nickel by powder of 8 micron diameters and 25 microns, according to powder of stainless steel, accounting for composite electromagnetic screen component volume ratio is 83%, iron nickel by powder account for composite electromagnetic screen component volume ratio be 8.5% and polyaniline powder account for the ratio that composite electromagnetic screen component volume ratio is 8.5% and carry out compound.After above-mentioned powder is mixed in proportion, utilize ultrasonic wave separating apparatus to disperse 20 minutes, obtain uniform composite electromagnetic screen component.Add paint for body material.The volume ratio of composite electromagnetic screen component and paint is respectively 18% and 82%.Mixed colloid is put into planetary ball mill ball milling and within 1 hour, obtain electromagnetic screen coating.According to the GJB GJB 6190-2008 of the People's Republic of China (PRC), it is for testing effectiveness of shielding on the resin substrate of 115 millimeters that shielding coating is sprayed on to diameter with spraying equipment.This sample its effectiveness of shielding in the range of frequency of 30MHz-1500MHz is 71-92dB after tested, and the loss of intensity that absorption portion causes is as calculated more than 29%.
embodiment 3
In the present embodiment, the metal-powder of relative conductivity >=0.02 is selected silver-coated copper powder end, and the ferromagnetic material powder of relative magnetic permeability >=1 is selected iron zinc powder, polymer dielectric material selection electrically conductive polyaniline powder.Select the silver-coated copper powder end of 20 micron diameters, the electrically conductive polyaniline powder through camphorsulfonic acid doping of the iron zinc powder of 20 micron diameters and 50 microns, according to silver-coated copper powder end, accounting for composite electromagnetic screen component volume ratio is 70%, iron zinc powder account for composite electromagnetic screen component volume ratio be 29% and polyaniline powder account for the ratio that composite electromagnetic screen component volume ratio is 1% and carry out compound.After above-mentioned powder is mixed in proportion, utilize ultrasonic wave separating apparatus to disperse 20 minutes, obtain uniform composite electromagnetic screen component.Adding acrylic resin is body material.The volume ratio of composite electromagnetic screen component and acrylic resin is respectively 40% and 60%.Mixed colloid is put into planetary ball mill ball milling and within 45 minutes, obtain electromagnetic screen coating.According to the GJB GJB 6190-2008 of the People's Republic of China (PRC), it is for testing effectiveness of shielding on the resin substrate of 115 millimeters that shielding coating is sprayed on to diameter with spraying equipment.This sample its effectiveness of shielding in the range of frequency of 30MHz-1500MHz is 65-83dB after tested, and the loss of intensity that absorption portion causes is as calculated more than 17%.
embodiment 4
In the present embodiment, the metal-powder of relative conductivity >=0.02 is selected metal nickel powder, and the ferromagnetic material powder of relative magnetic permeability >=1 is selected iron nickel by powder, polymer dielectric material selection electrically conductive polyaniline powder.Select the metal nickel powder of 6 micron diameters, the electrically conductive polyaniline powder through camphorsulfonic acid doping of the iron nickel by powder of 2 micron diameters and 1 micron, according to metal nickel powder, accounting for composite electromagnetic screen component volume ratio is 97%, iron nickel by powder account for composite electromagnetic screen component volume ratio be 2% and polyaniline powder account for the ratio that composite electromagnetic screen component volume ratio is 1% and carry out compound.After above-mentioned powder is mixed in proportion, utilize ultrasonic wave separating apparatus to disperse 20 minutes, obtain uniform composite electromagnetic screen component.Adding acrylic resin is body material.The volume ratio of composite electromagnetic screen component and acrylic resin is respectively 5% and 95%.Mixed colloid is put into planetary ball mill ball milling and within 45 minutes, obtain electromagnetic screen coating.According to the GJB GJB 6190-2008 of the People's Republic of China (PRC), it is for testing effectiveness of shielding on the resin substrate of 115 millimeters that shielding coating is sprayed on to diameter with spraying equipment.This sample its effectiveness of shielding in the range of frequency of 30MHz-1500MHz is 70-100dB after tested, and the loss of intensity that absorption portion causes is as calculated more than 12%.
embodiment 5
In the present embodiment, the metal-powder of relative conductivity >=0.02 is selected metal nickel powder, and the ferromagnetic material powder of relative magnetic permeability >=1 is selected iron nickel by powder, polymer dielectric material selection electrically conductive polyaniline powder.Select the metal nickel powder of 10 micron diameters, the iron nickel by powder of 16 micron diameters and the electrically conductive polyaniline powder of 30 microns, according to metal nickel powder, accounting for composite electromagnetic screen component volume ratio is 70%, it is 1% that iron nickel by powder accounts for composite electromagnetic screen component volume ratio, and electrically conductive polyaniline powder accounts for the ratio that composite electromagnetic screen component volume ratio is 29% and carries out compound.After above-mentioned powder is mixed in proportion, utilize ultrasonic wave separating apparatus to disperse 20 minutes, obtain uniform composite electromagnetic screen component.Adding acrylic resin is body material.The volume ratio of composite electromagnetic screen component and acrylic resin is respectively 12% and 88%.Mixed colloid is put into planetary ball mill ball milling and within 45 minutes, obtain electromagnetic screen coating.According to the GJB GJB 6190-2008 of the People's Republic of China (PRC), it is for testing effectiveness of shielding on the resin substrate of 115 millimeters that shielding coating is sprayed on to diameter with spraying equipment.This sample its effectiveness of shielding in the range of frequency of 30MHz-1500MHz is 70-100dB after tested, and the loss of intensity that absorption portion causes is as calculated more than 8%.
Claims (2)
1. the high-efficiency electromagnetic shielding material of a low reflection, it is characterized in that, comprise the composite electromagnetic screen component that the material by different electromagnetic propertys forms, this composite electromagnetic screen component is by the metal-powder of relative conductivity >=0.02, the ferromagnetic material powder of relative magnetic permeability >=1 and polymer dielectric material form, above-mentioned metal-powder is selected powder of stainless steel or metal nickel powder, above-mentioned ferromagnetic material powder is selected iron nickel by powder or ferrocobalt powder, the material of above-mentioned different electromagnetic propertys is obtained the electromagnetic shielding material with different electromagnetic shielding characteristics with different ratio mixing, wherein: in described composite electromagnetic screen component, the volume ratio of metal-powder is between 70%-97%, the volume ratio of ferromagnetic material powder is between 1%-29%, the volume ratio of polymer dielectric material is between 1%-29%, the diameter of the metal-powder adopting is at 2-20 micron, the diameter of the ferromagnetic material powder adopting is at 2-20 micron, the diameter of the polymer dielectric material adopting is at 1-50 micron, first preparation method mixes the powder of the compound different electromagnetic propertys of needs ratio as requested, then carry out ultrasonic dispersion and homogenizing, obtain adding body material to stir after uniform mixed powder, put into ball-grinding machine and carry out ball milling, the time of ball milling is greater than 20 minutes, obtains electromagnetic shielding material.
2. the high-efficiency electromagnetic shielding material of a kind of low reflection according to claim 1, it is characterized in that, the composite electromagnetic screen component consisting of the material of different electromagnetic propertys is mixed with into electromagnetic shielding material with body material, wherein the volume fraction of composite electromagnetic screen component is 5%-40%, body material volume fraction is 60%-95%, and body material is comprised of resin or paint.
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| CN109880344B (en) * | 2019-01-30 | 2021-02-23 | 中北大学 | Preparation method of low-reflection high-shielding waterborne polyurethane electromagnetic shielding composite foam |
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| CN101085842A (en) * | 2006-06-06 | 2007-12-12 | 西南科技大学 | Method for preparing electromagnetic shielding plastic master batch and composite plastic |
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