KR20060039277A - Paint for electromagnetic interference shielding and manufacturing method for the same - Google Patents

Abstract

Electromagnetic shielding paint is provided. Electromagnetic shielding paints include 10.0 to 30.0 wt% binder resin, 30.0 to 80.0 wt% solvent, 0.1 to 5.0 wt% dispersant, 0.1 to 5.0 wt% carbon nanotube, and 15.0 to 40.0 wt% metal powder or It comprises a metal fiber and the total content of the carbon nanotubes and the metal powder or metal fiber is characterized in that 20.0 ~ 40.0wt% with respect to the whole composition. Also provided is a method of producing an electromagnetic shielding paint.

Electromagnetic shielding paint, carbon nanotube, metal powder, binder resin, dispersant

Description

Paint for electromagnetic shielding and manufacturing method thereof {Paint for electromagnetic interference shielding and manufacturing method for the same}

1 is a flowchart for explaining a method for producing an electromagnetic shielding paint according to the present invention.

The present invention relates to an electromagnetic shielding paint and a method for manufacturing the same, and more particularly, to an electromagnetic shielding paint using a carbon nanotube and a metal powder and a method for manufacturing the same.

With the recent development of information and communication technology and the proliferation of electronic and communication devices, electromagnetic interference, which can affect them, has emerged as an important environmental problem. In order to minimize mutual malfunctions, it is necessary to develop electromagnetic shielding materials.

At present, most electromagnetic wave shielding materials are deposited in the form of thin films on the surface of products in consideration of the trend toward miniaturization and weight reduction of electric and electronic devices, low price and ease of design by mass production, or metal powder or carbon as a conductive filler in organic binder resin. The fiber etc. are mixed and used. However, these electromagnetic shielding materials still have problems in terms of processability, stability, and economics.

Recently, the development of conductive paint compositions has made significant advances over the 1980s. In the 1980s, when international electromagnetic compatibility standards were standardized, paint in the form of nickel (Ni) and silver (Ag) powders was the only form of electromagnetic shielding for coatings.

Early conductive coating compositions have had many difficulties in applying electrical and electronic devices due to deterioration of physical properties such as high density, high price, and low corrosion resistance. For the first time in the mid-1990s, the concept of hybrid conductive paint began to emerge by mixing pure silver powder and silver-coated copper powder for lower cost. However, the conductive paint composition for shielding electromagnetic waves, which is composed of metals, polymers, organic solvents, and the like, has a large stress due to high charge, corrosion resistance and adhesion to the substrate, except that the price is low. It still has a number of disadvantages such as being vulnerable.

That is, the conductive paint composition for shielding electromagnetic waves composed of conventional metals, polymers and organic solvents is a solution in which a polymer in the form of polypropylene, polyvinyl alcohol, nylon, polyurethane, or blends thereof is dissolved in an organic solvent. It was common to obtain by dispersing 40 wt% or more of a hybrid powder by metal powder, carbon fiber or a mixture thereof having excellent electrical conductivity.

As the metal powder, silver powder or copper coated with silver, which has the highest electrical conductivity, was used, and when the silver powder or copper coated with silver was dispersed in the polymer to about 40 wt%, a volume resistance of about 0.01 Ω · cm or less As a result, electromagnetic shielding effects of more than 50dB could be obtained.

However, in order to meet the more stringent electromagnetic interference standards, a lower electric volume resistance and a higher shielding effect are required. For this purpose, more metal powder must be dispersed in the polymer. However, when many metal powders are dispersed in a polymer, the electromagnetic shielding effect can be enhanced due to the improvement of electrical conductivity, but the mechanical properties including impact strength and adhesion are lowered, resulting in higher density and higher price. Many restrictions follow.

Recently, research into the electromagnetic wave shielding material made by dispersing carbon nanotubes as a conductive filler in a polymer has been actively conducted. Fig. 10 shows a high volume resistivity of 10? Cm and a low electromagnetic shielding efficiency of about 25 dB even when 40 wt% of carbon nanotubes are added. M Kim et al., Current Appl. Phys., (2004)] has difficulty in application as an electromagnetic shielding material.

Therefore, there is a need to develop an electromagnetic shielding material for paints having low volume resistance, high electromagnetic shielding rate, excellent impact strength, adhesion to a substrate, thermal stability, atmospheric stability, and low cost.

The technical problem to be achieved by the present invention is to use carbon nanotubes and metal powder to exhibit low volume resistance, high electromagnetic shielding rate, high impact strength, adhesion to substrate, thermal stability and atmospheric stability, and low cost electromagnetic shielding To provide a paint for the dragon.

Another technical problem to be achieved by the present invention is to provide a method of manufacturing the electromagnetic shielding paint.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

Electromagnetic shielding paint for solving the above technical problem is 10.0 ~ 30.0wt% binder resin, 30.0 ~ 80.0wt% solvent, 0.1 ~ 5.0wt% dispersant, 0.1 ~ 5.0wt% carbon nanotube, and 15.0 It comprises ~ 40.0wt% metal powder or metal fiber and the total content of the carbon nanotubes and the metal powder or metal fiber is characterized in that 20.0 ~ 40.0wt% with respect to the whole composition.

In order to solve the above technical problem, a method of manufacturing an electromagnetic shielding paint may include: purifying and surface modifying carbon nanotubes, preparing a polymer matrix solution by mixing a binder resin and a solvent, and preparing a carbon nanotube as a solvent and an interface. Preparing a first mixture by mixing the active agent, mixing a metal powder and a dispersant in the first mixture, followed by stirring to prepare a second mixture, and mixing the second mixture and the polymer matrix solution to prepare a paint composition in the form of a paste. Manufacturing step.

Specific details of other embodiments are included in the detailed description and the accompanying drawings.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and the general knowledge in the art to which the present invention pertains. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

The binder resin used in the present invention is used to complex the carbon nanotubes and the metal powders, which are conductive fillers, and may be the carbon nanotubes and the metal powders, regardless of molecular weight, density, molecular structure, and functional groups. All are applicable.

For example, water and a large affinity _{-OH, -COOH, -CONH 2, -NH} 2, -COO -, -SO3 - no cross-linking, such as, -NR ₃ ⁺ polymer is polyvinyl alcohol which is soluble in water, water-dispersible Polyurethanes, acrylic acids, maleic anhydrides and blends thereof can be used.

As the binder resin, polypropylene, polystyrene, nylon resin, polyurethane, polycarbonate, polyvinylidene fluoride, polyvinylpyrrolidone, polyacetate, polymethyl methacrylate, ABS (Acrylonitrile) Butadiene-Styrene terpolymer) and blends thereof are available.

However, as the binder resin, in a product requiring an electromagnetic wave shielding material having thermal and mechanical impact strength, it is preferable to use a polymer having excellent elongation characteristics and impact absorption effects, such as silicone rubber or polyurethane.

The content of the binder resin is preferably 10.0 to 30.0 wt%.

The solvent is used to dissolve the binder resin or to disperse the carbon nanotubes and the metal powder into a slurry mixture.

Substances which can be used as the solvent include one or two or more of ethanol, methyl ethyl ketone, isopropyl alcohol, toluene, N-methylpyrrolidone, ethyl acetate, butyl celusolve or mixed with water in the form of an aqueous solution. However, the solvent for dissolving the binder resin or dispersing the carbon nanotubes and the metal powder may be the same or different solvents depending on each process.

It is preferable that the content of the solvent is 30.0-80.0 wt%.

For example, when a binder resin is used that can be dissolved in an organic solvent and the solvent is a nonvolatile and nonpolar mixture of N-methylpyrrolidone and a carbon-based organic solvent, the electrical and mechanical properties and coating properties of the composition may be different. Improved.

In addition, when water-dispersible polyurethane is used as the binder resin and ethanol is used as the solvent, it is possible to prepare an environmentally friendly conductive composition for coating having little volatile organic matter.

The dispersant may include all or one or two or more of a surfactant, a wet dispersant, an antifoaming agent, a surfactant, a leveling agent, and a thickener.

The surfactant is added to facilitate the dispersion when the carbon nanotubes are dispersed in a solvent, and a compound containing one or two or more of nonionic, cationic, and anionic compounds may be used. The content of carbon nanotubes to be described later is preferably 0.1 to 2.0 wt%.

Wetting and dispersing agents, defoamers, interfacial binders, leveling agents are added to facilitate the dispersion of the metal powder in a slurry containing a solvent or carbon nanotubes, as well as to improve the coating surface properties of the paint composition, A chlorine compound, a fluorine compound, a silicon compound, a non-silicon compound, a glycol derivative, an epoxy, carboxyl, or one containing two or more of the amines at the amine end may be used, and the content thereof is 0.1 to the carbon nanotube content. It is preferable to set it as -2.0 wt%.

The thickener is added to improve the coating properties and storage stability by providing a constant viscosity to the paste-type composition in which the carbon nanotubes and the metal powder are dispersed in a binder resin, a solvent, and a dispersant, among acrylic, cellulose, and urethane compounds. It contains one or two, the content is preferably 0.1 to 2.0wt% with respect to the carbon nanotube content.

Carbon nanotubes can be used regardless of the manufacturing method such as chemical vapor deposition, arc discharge, plasma torch, ion bombardment, etc., and single-walled nanotubes (SWNT) ), Multi-walled nanotubes (MWNTs), and double-walled nanotubes (DWNTs) such as carbon nanotubes of any shape, diameter and length Nanotubes are available.

Carbon nanotubes used in the present invention is preferably used to refine the surface and to improve the dispersibility in the polymer resin.

Purification and surface modification methods include acid reforming methods and fluorine gas reforming methods. However, purification and surface modification results were analyzed using Fourier transform infrared spectroscopy. ( ¹ ) Phenyl between 1300 cm ^-1 and 1100 cm ^-1 -carbonyl stretch CC bond peak characteristic is present CNT, ②1300㎝ 1100㎝ ^-1 and ^-1 among the phenyl to-carbonyl between carbonyl CC styryl latch coupled with 1570㎝ ^-1 and ^-1 1430㎝ Nick CC stretch bond and 1650㎝ ^-1 carboxylic group of the C = O styryl phenyl reching between the vibration characteristic peaks are present at the same time carbon nanotubes, ③1300㎝ ^-1 and ^-1 1100㎝ near-carbonyl CC styryl latch combined with 1650 ㎝ ^-1 vicinity of the carboxylic group of the C = O vibration and that -OH styryl reching coupling characteristic peak is present CNT, CF binding properties of ④1250㎝ ^-1 vicinity of the peak at the same time 3550㎝ ^-1 is present at the same time carbon The use of carbon nanotubes comprising one or more carbon nanotubes of the nanotubes are preferred.

When the carbon nanotube content is less than 0.1wt%, the interaction between the metal powder and the carbon nanotubes is not good, and thus it may not show an appropriate level of electrical conductivity. When the carbon nanotube content exceeds 5.0wt%, the higher electrical conductivity is obtained. Although high shielding effect can be obtained, there is a problem in that dispersion is difficult and thus the coating surface properties are deteriorated. Therefore, the content of carbon nanotubes is preferably set to 0.1 ~ 5.0wt%.

The metal powder is used as a conductive filler other than carbon nanotubes, and it is preferable to use the metal powder, but the same or similar effect may be obtained even by using the metal fiber.

The metal powder can be used as long as it is a conductive metal powder having an electrical conductivity of 10 ⁴ S / cm or more, but the most commercially available metal powder such as silver powder and copper coated by silver is used. It is desirable to.

As described above, metal powder is preferably used as the conductive filler, but metal fiber may be used. Examples of the metal fiber that can be used include steel fiber, copper fiber, aluminum fiber, and nickel fiber.

If the content ratio of the metal powder or the metal fiber is less than 15.0 wt%, the electrical conductivity is low, and percolation cannot be formed due to the effective interaction with the carbon nanotubes. Since it falls, it is preferable to set it as 15.0-40.0 wt%.

The total content of carbon nanotubes and metal powder or metal fibers used as conductive fillers is preferably 20.0 to 40.0 wt% with respect to the entire paint composition. When the content is less than 20 wt%, sufficient conductivity and shielding efficiency cannot be obtained. The paint may exhibit unsuitable properties, and if it is 40wt% or more, the coating surface properties may be deteriorated by excessive conductive filler content, which is not advantageous in terms of cost.

The shape of the electromagnetic shielding paint has a liquid phase having a viscosity depending on the content of the solvent.

Therefore, the electromagnetic shielding paint according to the present invention can be used in various forms, such as for printing, tape casting, and spray.

1 is a flowchart for explaining a method for producing an electromagnetic shielding paint according to the present invention.

Hereinafter, a method of manufacturing the electromagnetic shielding paint according to the present invention will be described with reference to FIG. 1.

First, the purified and surface-modified carbon nanotubes are prepared through purification and surface modification (S100).

The reason that carbon nanotubes undergo purification and surface modification is to introduce functional groups such as amines, carboxyl, and hydroxyl groups on the surface of carbon nanotubes, thereby minimizing intermolecular bonds between carbon nanotubes. This is to improve the dispersion characteristics in the matrix.

Purification and surface modification can be done using acid reforming or fluorine gas reforming. However, the results of surface analysis by Fourier transform infrared spectroscopy ① Between 1300cm ^-1 and 1100cm ^-1 phenyl-carbonyl stretch CC bond peak characteristic is present the carbon nanotube, and 1100㎝ ②1300㎝ ^{-1 -1-phenyl} between to-carbonyl between carbonyl CC styryl latch coupled with 1570㎝ ^-1 and ^-1 1430㎝ Nick CC between and stretch bonded 1650㎝ ^-1 vicinity carboxylic group of the C = O styryl reching vibration characteristic peaks are present at the same time carbon nanotubes, and 1100㎝ ③1300㎝ ^{-1 -1-phenyl-carbonyl} CC styryl latch coupled with CF binding characteristics of the peak is present at the same time 1650㎝ ^-1 vicinity of the carboxyl carbon nanotube -OH coupling characteristic peak is present at the same time in the metallic group of C = O vibration and styryl reching 3550㎝ ^{-1, -1} vicinity ④1250㎝ doing It makes a hydrogen or nanotubes are preferred.

However, this step may be omitted when using purified carbon nanotubes and the surface is modified.

Next, a binder resin and a solvent are mixed to prepare a polymer matrix solution (S110).

This is to influence the viscosity and coating surface properties of the electromagnetic wave shielding paint composition to be finally produced later, this step can be omitted when using a polymer of water-dispersible polyurethane or elejeonjeon.

Next, the first mixture is prepared by mixing the purified and surface-modified carbon nanotubes with a solvent and a surfactant (S120).

In this case, the solvent used may be the same as the solvent in which the binder resin is dissolved, but in some cases, in order to lower the polarity of the solvent, a non-polar solvent may be mixed or another second solvent or an aqueous solution containing water may be used. It may be.

The reason for adding the surfactant is to improve the dispersibility of the carbon nanotubes, and may include one or two or more of nonionic, cationic, and anionic compounds, the content of which is 0.1 to the carbon nanotube content. It is preferable to set it as -2.0 wt%.

Next, a second mixture is prepared by mixing and stirring a metal powder (or metal fiber) and a dispersant in the first mixture (S130).

This step is a wet dispersion process of the metal powder, the metal powder is preferably used silver powder or silver powder coated copper powder.

The reason for adding the dispersant is to increase the dispersibility of the metal powder, and usable dispersants include one or two or more of a chlorine compound, a fluorine compound, a silicone compound, a non-silicone compound, and a glycol derivative. The content is preferably added 0.1 ~ 2.0wt% relative to the metal powder.

The reason for the stirring is to facilitate the mixing of the first mixture and the metal powder so that the metal powder can be more dispersed.

The same result can be obtained by using a method in which the metal powder and the dispersant are mixed first and then mixed with the first mixture, rather than the metal powder and the dispersant being added to the first mixture.

In addition, the same results can be obtained by simultaneously mixing carbon nanotubes, metal powders, surfactants, and dispersants.

Next, the second mixture and the polymer matrix solution are mixed to prepare a composition in the form of a paste (S140).

The second mixture and the polymer matrix solution are mixed using a Henschel mixer, a Rodige mixer, a 3-roll or a homogenizer, and the stirring process using the vortex phenomenon and the screen phenomenon of the mixture by high-speed stirring is more effective. Instead of the general impeller, the basket is made of zirconia balls and impellers with a size of 1 μm to 5 μm in the basket, and the outside of the basket is a mesh to facilitate the pulverization of aggregates of carbon nanotubes and metal powders. , The mechanical properties could be improved.

The composition can be prepared both for screen printing, tape casting, and spray by adjusting the type and content of the solvent used.

In addition, the storage stability and flow characteristics of the composition prepared in this step may further include the step of adding a thickener to improve the coating properties (S150).

At this time, the thickener that can be used may be acrylic, urethane, cellulose-based, the content is preferably 0.1 ~ 2.0wt% compared to carbon nanotubes.

Hereinafter will be described with specific experimental examples that the electrical conductivity and shielding efficiency of the electromagnetic shielding paint according to the present invention is excellent. Descriptions not described herein are omitted because they are sufficiently technically inferred by those skilled in the art.

 (Unit: wt%)

Table 1 shows water-dispersible polyurethane containing 64% of water as binder resin, butyl cellosolve solution as solvent, fluorine-based compound, glycol-based compound, acryl-based compound, and carbon nanotube in a 1: 3 mixture of nitric acid and sulfuric acid. After the purification and surface modification process of stirring for 1 hour at a temperature of 40 ℃ in a 25% aqueous solution, the metal powder was prepared by the above-described manufacturing method for the electromagnetic shielding paint using silver powder, and then ethanol was added thereto. After dilution, the polyethylene terephthalate (PET) film was spray coated using a spray gun, and the surface resistivity and the electromagnetic shielding efficiency were measured.

Surface resistivity was measured according to MIL-G-835288, and 3540 mΩ Hi-tester (Hioki Co.) was used as a measuring instrument. Specimen size was 25.4mm in width and 35.0mm in length, thickness was 5.0-40.0㎛ and specific resistance was measured in units of Ω / □.

Electromagnetic shielding efficiency was measured using a 133.0 mm diameter test specimen using an Agilent 8722ES network analyzer (Agilent, USA) and a 2-port flanged coaxial holder (EM-2107, Electro-Metrics, USA) according to ASTM D4935-89. Was measured in the range of 50 MHz to 6 GHz. Shielding efficiency was calculated by measuring s-parameter, S ₂₁ , and return loss using S ₁₁ . S ₂₁ denotes a transmission amount of the incident electromagnetic wave and serves as a criterion for determining shielding efficiency.

As shown in Table 1, when coating the electromagnetic shielding paint according to the present invention, it can be seen that the surface specific resistance is all 0.5 Ω / □ or less, and the shielding efficiency can be obtained a value of 50 dB or more.

In particular, in the case of Experimental Example 2 and Experimental Example 5 it can be seen that the surface specific resistance is 0.1 ~ 0.15Ω / □, the shielding efficiency has a very excellent property of 80dB or more.

 (Unit: wt%)

Table 2 shows polymethmethylacrylate as the binder resin, toluene and N-methylpyrrolidone (NMP) as the solvent, fluorine-based compound, glycol-based compound, acryl-based compound, and carbon nanotube as the dispersant. The same metal powder was used as the one used in the above, and the same metal powder as that used in Experimental Examples 1 to 5 was used as the silver powder.

At this time, the toluene solvent is used to dissolve the binder resin, NMP is used to disperse the carbon nanotubes and silver powder.

Surface resistivity and shielding efficiency were the same as those measured in Experimental Examples 1 to 5 above.

As shown in Table 2, the surface resistivity and shielding efficiency of the binder resin were polymethylmethylacrylate, the solvent was toluene and N-methylpyrrolidone (NMP), and the dispersant was a fluorine compound, a glycol compound, and an acrylic compound. However, in Experimental Example 8, as the amount of carbon nanotubes and silver powder was reduced, the surface resistivity was 2.34x10 ³ Ω / □, which appeared to have a non-conductive property. Thus, more than a predetermined amount of carbon nanotubes and metal powder were added. I could see.

 (Unit: wt%)

Table 3 compares the case where only one of carbon nanotubes or metal powders is used as the conductive filler in the binder resin and the solvent according to the present invention.

As shown in Table 3, in Comparative Examples 1 to 3, when only carbon nanotubes were used as the conductive filler without adding the metal powder, the uniformity of the coating film was also decreased and the surface specific resistance was very high. As a result, the electromagnetic shielding efficiency was also very high. It can be seen that low.

In Comparative Example 4, only 44 wt% of the conductive powder was added without adding carbon nanotubes, but the film uniformity was relatively good, the surface resistivity was low, and the shielding efficiency was about 70 dB.

However, due to the fact that as the metal powder is added in a large amount, the moldability, impact resistance, light weight, and cost reduction effect are decreased, in Experimental Examples 1 to 8, the metal powder is added at 44 wt% or less, but a small amount of carbon nanotube is added. In this case, the surface resistivity is lower than that of Comparative Example 4, and the shielding efficiency is higher. Therefore, the use of metal powder and carbon nanotubes at the same time is superior to the shielding material as well as the formability of the shielding material. It is also advantageous in terms of impact resistance, light weight, and cost reduction effect.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiments but may be manufactured in various forms, and having ordinary skill in the art to which the present invention pertains. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

 As described above, according to the electromagnetic wave shielding coating agent and a method of manufacturing the same, one or two or more of the following effects are obtained.

First, it is possible to overcome the disadvantages of high density and high weight, which were obstacles in the practical use of the existing shielding material.

Second, it is possible to lower the content of the metal powder and increase the content of the polymer to achieve cost reduction and weight reduction, as well as to increase mechanical properties such as impact resistance and adhesion.

Third, because it uses a relatively low content of metal powder and a relatively high polymer resin, it shows a low density and a high volume per unit weight, and therefore, when coated with the same thickness, there is an advantage of coating more area. .

Claims (14)

10.0-30.0 wt% binder resin, 30.0-80.0 wt% solvent, 0.1-5.0 wt% dispersant, 0.1-5.0 wt% carbon nanotube, and 15.0-40.0 wt% metal powder or metal fiber The total content of the carbon nanotubes and the metal powder or metal fiber is 20.0 ~ 40.0wt% based on the total composition of the electromagnetic shielding paint. The method of claim 1, The binder resin may be polyvinyl alcohol, water dispersible polyurethane, acrylic acid, maleic anhydride, polypropylene, polystyrene, nylon resin, polyurethane, polycarbonate, polyvinylidene fluoride, polyvinylpyrrolidone, polyacetate, poly Electromagnetic shielding paint comprising one or more of methyl methacrylate, ABS resin, silicone rubber and polyurethane. The method of claim 1, The solvent includes one or two or more of ethanol, methyl ethyl ketone, isopropyl alcohol, toluene, N-methylpyrrolidone, ethyl acetate, and butyl cerusolve or an aqueous solution for shielding electromagnetic waves. The method of claim 1, The dispersant may include one or two or more of a surfactant, a wet dispersant, an antifoaming agent, an interface binder, a leveling agent, and a thickener. The method of claim 1, The carbon nanotubes are carbon nanotubes having a phenyl-carbonyl CC stretch binding characteristic peak between ①1300 cm ^-1 and 1100cm ^{-1 as a} result of surface analysis by Fourier transform infrared spectroscopy, and ② between 1300cm ^-1 and 1100cm ^-1 . phenyl-carbonyl CC styryl latch coupled with 1570㎝ ^-1 and ^-1 1430㎝ between the carbonyl stretch Nick CC bond and 1650㎝ ^-1 vicinity of the carboxylic group of the C = O styryl reching vibration characteristic peaks are present at the same time carbon nanotubes, and ③1300㎝ ^-1-phenyl between 1100㎝ ^-1 - carbonyl CC styryl latch coupled with 1650㎝ ^-1 near the carboxylic group of the C = O styryl reching -OH in vibration and 3550㎝ ^-1 A carbon nanotube having a binding characteristic peak at the same time, and one or two or more carbon nanotubes at the same time having a CF binding characteristic peak near ④1250 cm ^-1 . The method of claim 1, The metal powder is silver powder and / or silver coated copper powder is electromagnetic shielding paint. The method of claim 1, The metal fiber is an electromagnetic shielding paint comprising one or more of steel fiber, copper fiber, aluminum fiber, nickel fiber. The method of claim 1, The binder resin is a water dispersible polyurethane having a water content of 56.0 to 66.0 wt%, and the solvent includes one or two or more of ethyl acetate, butyl cellosolve, aqueous solution of butyl cellosolve, and ethyl acetate. . The method of claim 4, wherein The surfactant includes one or two or more of nonionic, cationic, and anionic compounds, the content of which is 0.1 to 2.0 wt% based on carbon nanotube content. The method of claim 4, wherein The wetting and dispersing agent, the antifoaming agent, the interfacial binder, the leveling agent includes one or two or more of a chlorine compound, a fluorine compound, a silicone compound, a non-silicone compound, a glycol derivative epoxy, carboxyl, and an amine terminal at the amine end, and the content thereof is Electromagnetic shielding paint with 0.1 ~ 2.0wt% of carbon nanotube content. The method of claim 4, wherein The thickener includes one or two or more of acrylic, cellulose, and urethane, the content of which is 0.1 ~ 2.0wt% based on the carbon nanotube content of the electromagnetic shielding paint. (a) purifying and surface modifying carbon nanotubes; (b) mixing a binder resin and a solvent to prepare a polymer matrix solution; (c) mixing the carbon nanotubes with a solvent and a surfactant to prepare a first mixture; (d) mixing a metal powder and a dispersant in the first mixture and then stirring to prepare a second mixture; And (e) mixing the second mixture and the polymer matrix solution to prepare a composition in the form of a paste, the method of manufacturing an electromagnetic shielding paint. The method of claim 12, The method of claim 1, further comprising adding an acrylic, cellulose or urethane thickener to the paste composition. The method of claim 12, Purifying and surface-modifying the carbon nanotubes before the first mixture to prepare a method for producing a paint for shielding electromagnetic waves.

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