KR101820942B1 - Magentic shielding material for extremely low frequency and the preparing method thereof - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to a coating composition for shielding an extremely low frequency to magnetic field, a magnetic shielding material using the same, and more particularly, to a coating composition for shielding a magnetic field at an extremely low frequency band region of less than 60 Hz A magnetic field shielding material using the same, and a method of manufacturing the same.

Description

Field of the Invention [0001] The present invention relates to a shielding material for extremely low frequency and magnetic field,

TECHNICAL FIELD The present invention relates to a coating composition for shielding an extremely low frequency to magnetic field, a magnetic shielding material using the same, and more particularly, to a coating composition for shielding a magnetic field at an extremely low frequency band region of less than 60 Hz A magnetic field shielding material using the same, and a method of manufacturing the same.

Recently, with the rapid development of industrial civilization, the use of electric, electronic and communication devices for private and military use is expanding. However, since these devices are providing convenience to human beings and electromagnetic waves generated from the devices cause various harmful elements, researches on electromagnetic wave shielding are actively conducted to prevent them. Electromagnetic field is the space where electric field and magnetic field affect. It is also called electromagnetic field. There are many kinds in electromagnetic field, and their properties and influences are very different depending on frequency. Particularly, electromagnetic shielding is referred to as electromagnetic interference (EMI) in a region of 30 kHz or more, and shielding electromagnetic waves radiated by reflection and / or absorption by a material. Electromagnetic shielding is distinguished from magnetic shielding, which is magnetic field shielding of extreme low frequency (ELF).

Research on electromagnetic wave shielding materials has been actively reported since the 2000s. In general, metal materials with good conductivity are used as shielding materials. Carbon materials and the like are composite material with polymer resin, and electromagnetic wave shielding materials in a high frequency range are being studied in the form of building exterior materials, sheets and paints.

In general, a shielding effect is high due to a high absorption loss in a high frequency range, but a low shielding effect due to a low reflection loss and an absorption loss in a low frequency range. Therefore, the extremely low frequency magnetic field of 50 to 60 Hz is difficult to be shielded easily, and the absorption loss must be increased by using thick high permeability material in order to obtain high shielding.

However, studies on the magnetic shielding in the extremely low frequency region are hardly found in the form of a paper in domestic and foreign countries. Some metal materials such as Ni-based alloy (MuMETAL®, MAGNETIC SHIELD, USA) and permalloy are sold as products, Such a metal-based material is disadvantageous in that it is expensive and heavy, and thus it is expected to be limited to be used for mobile devices such as mobile devices, household appliances, communication equipment, and automobiles.

In particular, there have been no reports of ultra-low frequency shielding studies using carbon materials, and commercial products are hard to find.

Korean Patent No. 10-744412 (Registered on July 24, 2007) Korean Registered Patent No. 10-148163 (Registered on 2015.01.06)

Accordingly, it is an object of the present invention to provide a coating composition for shielding an extremely low frequency magnetic field having a shielding effect of a magnetic field in an extremely low frequency band region of less than 60 Hz, a magnetic field shielding material using the same, and a method for manufacturing the same.

Accordingly, the present invention relates to a carbon-based powder having an average particle size of 0.01 to 50 탆 and an average particle size of 0.1 to 5 g / cm ³ ; And a binder solution containing an organic resin, wherein the carbonaceous powder includes at least one selected from the group consisting of carbon black and natural graphite.

In one preferred embodiment of the present invention, the composition may include 5 to 20 parts by weight of the carbon-based powder relative to 100 parts by weight of the binder solution.

In a preferred embodiment of the present invention, the carbon-based powder may have an average particle size of 15 to 45 μm and an average density of 1.5 to 2.0 g / cm ³ .

In one preferred embodiment of the present invention, the organic resin may include at least one selected from the group consisting of a lacquer resin, an epoxy resin and a phenol resin.

Further, another aspect of the present invention is a semiconductor device comprising: a conductor; An insulating film provided on an upper surface of the conductor; And a coating layer on the upper surface of the insulating layer, the coating layer being formed by curing the composition, the coating layer for shielding a magnetic field of an extremely low frequency and a magnetic field.

In a preferred embodiment of the present invention, the coating layer may have a thickness of 50 to 1000 mu m.

In a preferred embodiment of the present invention, the coating layer for shielding a very low frequency magnetic field may have a magnetic shielding reduction ratio of about 35% to about 40% with respect to 50 to 60 Hz when the thickness of the coating layer is 450 to 500 μm.

According to still another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: (1) forming an insulating film by coating and curing at least one of epoxy resin and lacquer resin on an upper surface of a conductor; And coating the coating material on the upper surface of the insulating layer with a coating agent containing the coating composition and curing the coating material to form a coating film for shielding a magnetic field of an extremely low frequency region.

In one preferred embodiment of the present invention, the first stage curing may be performed at 20 to 150 ° C for 30 minutes to 100 minutes.

In one preferred embodiment of the present invention, the first insulating layer may have a thickness of 20 to 50 탆.

In one preferred embodiment of the present invention, the two-stage curing may be performed at 20 to 150 ° C for 30 minutes to 100 minutes.

In one preferred embodiment of the present invention, the thickness of the insulating layer may be 20 to 50 占 퐉, and the thickness of the coating layer for shielding the magnetic field may be 50 to 1000 占 퐉.

According to the present invention, a magnetic field can be shielded in an extremely low frequency magnetic field region of less than 60 Hz, so that it can be effectively used in various home appliances, automobiles, communication devices, and transmission towers.

Further, the coating film for magnetic shielding at the extremely low frequency region formed by the coating composition for shielding magnetic field can maintain high conductivity even if it is formed very thin, and has excellent adhesion to both injection-molded and foamable plastics, Development and the like, but also an excellent effect such as color, adhesiveness, moisture resistance and electromagnetic wave shielding as an organic / inorganic composite agent containing an organic resin.

1 is a scanning electron microscope image of a carbon-based particle according to a preferred embodiment of the present invention.
2 is an image showing a thickness measurement position of a specimen according to a preferred embodiment of the present invention.
3 is a graph illustrating the thickness of a coating film for shielding an extremely low frequency magnetic field according to a preferred embodiment of the present invention.
FIG. 4 is a graph illustrating a change in magnetic field according to a thickness of an extremely low frequency magnetic field shielding material according to a preferred embodiment of the present invention.
5 is a schematic view of a method of manufacturing an extremely low frequency magnetic field shielding material according to a preferred embodiment of the present invention.
FIG. 6 is a graph showing magnetic field measurements according to a voltage application amount of an extremely low frequency magnetic field shielding material according to a preferred embodiment of the present invention.

The present invention can shield a magnetic field in an extremely low frequency band region of less than 60 Hz, and thus can be effectively utilized in various home appliances, automobiles, communication devices, and transmission towers. Hereinafter, the present invention will be described in more detail.

The coating composition for shielding extremely low frequency versus magnetic field according to the present invention comprises a carbon-based powder. The carbon-based powder includes at least one selected from the group consisting of carbon black and natural graphite, preferably carbon black. The carbon-based powder preferably has an average particle size of from 0.01 to 50 μm and an average density of from 0.1 to 5 g / cm ^3. Preferably, the carbon-based powder has an average particle size of from 15 to 45 μm, 1.5 to 2.0 g / cm < ³ > is preferable. At this time, when the average particle size of the carbon-based powder is less than 0.01 탆, the powder is aggregated to form irregularities, thereby making it difficult to form a uniform coating layer. When the average particle size is more than 50 탆, it is difficult to form the coating layer cleanly. Further, the powder and a hard off thickness control of the coating layer is a problem in the coating layer, when the average density of 5 g / cm ³ or more, the surface of the coating layer is not clear before this case the average density of 0.1 g / cm ³ less than the coating film curing There may be a problem that it can not be formed.

In one preferred embodiment of the present invention, the composition may include 5 to 20 parts by weight, preferably 10 to 15 parts by weight, of the carbon-based powder per 100 parts by weight of the binder solution. When the composition contains less than 5 parts by weight of the carbon-based powder relative to 100 parts by weight of the binder solution, there is a problem that the magnetic shielding effect is lowered. When the composition is more than 20 parts by weight, viscosity of the coating solution increases, There is a problem.

When a coating film is formed of a coating liquid composition in which the carbon-based powder satisfies the above-mentioned range, a better magnetic shielding efficiency can be exhibited. The organic resin may include at least one selected from the group consisting of a lacquer resin, an epoxy resin and a phenol resin. Preferably a lacquer-based resin and an epoxy-based resin, and more preferably a lacquer-based resin.

Further, another aspect of the present invention is a semiconductor device comprising: a conductor; An insulating film provided on an upper surface of the conductor; And a coating layer on the upper surface of the insulating layer, the coating layer being formed by curing the composition, the coating layer for shielding a magnetic field of an extremely low frequency and a magnetic field.

The extremely low frequency magnetic field shielding material according to the present invention includes a conductor and an insulating film provided on an upper surface of the conductor. The insulating film is provided to prevent the conductor from being magnetized by a magnetic field. The thickness of the insulating film is preferably 20 to 50 mu m, more preferably 30 to 50 mu m. If the thickness of the insulating layer is 20 m or less, a desired insulating effect for preventing magnetization of the conductive layer can not be obtained. If the thickness of the insulating layer is more than 50 m, .

In addition, the present invention includes a coating film for shielding a magnetic field with a very low frequency which is formed on the upper surface of the insulating coating layer and formed by curing the composition. The thickness of the coating film may be 50-1000 mu m, and preferably 100-600 mu m. When the thickness of the coating film is less than 50 탆, the magnetic shielding effect is deteriorated. When the thickness exceeds 1000 탆, it is difficult to form the coating layer cleanly.

In a preferred embodiment of the present invention, the coating layer for shielding an extremely low frequency magnetic field may have a magnetic shielding reduction ratio of 35 to 40% for 50 to 60 Hz when the thickness of the coating layer is 450 to 500 탆, Preferably, when the thickness of the coating film is 450 to 460 μm, the magnetic shielding reduction rate may be 37 to 39% at 50 to 60 Hz.

In one embodiment of the present invention, the coating may have a resistance change rate within ± 20% after 7 days at 85% and 85 ° C relative humidity, and preferably a resistance change rate within ± 5% .

In a preferred embodiment of the present invention, the resistance value may be 0.015 to 0.1 Ohm / Sq when the dry film thickness of the coating is 25 m, and preferably 0.015 Ohm / Sq or less.

According to another aspect of the present invention, there is provided a method of manufacturing the ultra-low frequency magnetic field shielding material, comprising the steps of: forming an insulating film by coating and curing an organic resin on an upper surface of a conductor; And coating a coating material containing the coating composition on one surface of the insulating film and then curing the coating material to form a coating film for shielding a magnetic field at an extremely low frequency.

In one preferred embodiment of the present invention, the first step is a step of coating and curing an organic resin on the upper surface of the conductive body to form an insulating film, and the insulating film is provided to prevent the conductive body from being magnetized by a magnetic field And can be formed by coating and curing an organic resin.

At this time, the coating may be carried out by one method selected from the group consisting of spraying, rolling, deeping and brushing, preferably by a method of rolling have. The curing may be carried out at 20 to 150 ° C for 30 minutes to 100 minutes, preferably at 15 to 60 ° C for 30 minutes to 100 minutes. At this time, the thickness of the insulating film in the first step is preferably 20 to 50 mu m, more preferably 30 to 50 mu m. When the thickness of the insulating film is less than 20 탆, there is a problem in that it is not insulated. When the thickness exceeds 50 탆, the thickness of the entire product including the shielding material according to the present invention becomes thick.

In a preferred embodiment of the present invention, the step 2 is a step of coating the coating composition on the upper surface of the insulating film and then curing the coating composition to form a coating film for shielding a magnetic field at an extremely low frequency, The coating may be formed by coating a coating composition for shielding at an extremely low frequency and a magnetic field according to one of the methods selected from the group consisting of spraying, rolling, deepening and brushing Can be carried out, and preferably can be carried out by the method of spraying. The two-stage curing may be performed at 20 to 150 ° C for 30 minutes to 100 minutes, preferably at 50 to 70 ° C for 30 minutes to 100 minutes.

At this time, the thickness of the coating layer may be 50-1000 mu m, preferably 100-600 mu m. When the thickness of the coating film is less than 50 탆, the magnetic shielding effect is deteriorated. When the thickness exceeds 1000 탆, it is difficult to form the coating layer cleanly.

Hereinafter, the present invention will be described in more detail with reference to the following examples. The following examples are provided to illustrate the present invention and do not limit the scope of the present invention.

[Example]

Example 1. Preparation of Coatings for Very Low Frequency vs. Magnetic Field Shielding

A carbon black powder (Super-P, TIMCAL, swiss) having an average density of 0.16 g / cm ³ and an average particle size of 0.040 탆 was mixed with 10 wt% of a lacquer resin (LOV HS lacquer, Samhwa paints) A magnetic shielding coating agent was prepared.

Examples 2 to 3. Preparation of a Coating Agent for Ultra-Low Frequency vs. Magnetic Field Shielding

Except that carbon black (DENKI KAGAKU KOGYO KK Japan) and natural graphite (HC-198, HyundaiComma, Korea) were used as the carbon particles as shown in the following Table 1, and the extremely low frequency magnetic field shielding Was prepared.

division Density (g / cm ³ ) Average particle size (탆) Raw material name manufacturer Example 1 0.16 0.040 Super-P TIMCAL, Swiss Example 2 0.25 0.035 Denka Black DENKI KAGAKU KOGYO K.K., Japan Example 3 1.73 25 HC-198 HyundaiCome, Korea

[Comparative Example]

Comparative Examples 1 and 2. Manufacture of Coatings for Extreme Low Frequency vs. Magnetic Field Shielding

Except that carbon particles as shown in the following Table 1 were used, respectively, in the same manner as in Example 2 and Example 3, respectively.

division Density (g / cm ³ ) Average particle size (탆) Raw material name manufacturer Comparative Example 1 0.078 0.0067 Denka Black DENKI KAGAKU KOGYO K.K., Japan Comparative Example 2 6.2 55 HC-198 HyundaiCome, Korea

Production Example 1. Preparation of Coating Film for Ultra-Low Frequency and Magnetic Field Shielding

(1) A circular aluminum plate having a diameter of 88 mm and a thickness of 0.36 T was coated with a lacquer resin (LOV HS lacquer, Samhwa paint) on the upper surface of the circular aluminum plate, and then powder coating was carried out using air pressure spray coating Thereby forming an insulating film.

(2) The coating material of Example 1 was coated on the upper surface of the insulating film and then cured at 60 ° C for 1 hour to prepare a coating film for shielding the magnetic field.

Production Example 2. Preparation of Coating Film for Ultra-Low Frequency and Magnetic Field Shielding

A coating film for shielding an extremely low frequency magnetic field was prepared in the same manner as in Production Example 1, except that the coating material of Example 2 was used in the step (2) of Production Example 2.

Production Example 3. Preparation of Coating Film for Ultra-Low Frequency and Magnetic Field Shielding

A coating film for shielding an extremely low frequency magnetic field was prepared in the same manner as in Production Example 1, except that the coating material of Example 3 was used in the step (2) of Production Example 2.

COMPARATIVE PREPARATION EXAMPLE 1. Preparation of Coating Film for Ultra-Low Frequency vs. Magnetic Field Shielding

A coating film for shielding an extremely low frequency magnetic field was prepared in the same manner as in Production Example 1, except that the coating agent of Comparative Example 1 was used in the step (2) of Production Example 1.

COMPARATIVE EXAMPLE 2 Preparation of a Coating Film for Ultra-Low Frequency and Magnetic Field Shielding

A coating film for shielding an extremely low frequency magnetic field was prepared in the same manner as in Preparation Example 2, except that the coating material of Comparative Example 2 was used in the step (2) of Production Example 1.

[Experimental Example]

Experimental Example 1. Observation of fine particles of carbon-based powder

In order to observe the carbon-based powder used in the coating composition according to the present invention, the shape of the fine particles was observed using a scanning electron microscope (FE-SEM, 6500F, JEOL), and the results are shown in FIG. 1 (a) is the fine particle of Example 1, (b) is the fine particle of Example 2, and (c) is the image of the fine particle of Example 3.

According to FIG. 1, it was confirmed that the Super-P of Example 1 and the Denka Black of Example 2 were aggregated spherical particles, and HC-198 of Example 3 was in a plate form.

Experimental Example 2. Measurement of Coating Film Thickness for Magnetic Field Shielding

In order to measure the thickness of the coating film for magnetic shielding according to the present invention, the thicknesses of the specimens prepared in Preparations 1 to 3 and Comparative Preparations 1 and 2 were measured at the inner and midpoints of 20 mm at the upper and lower left and right ends 2), and the results are shown in Table 3 and FIG.

division Manufacturing example Production Example 1
Super-P Production Example 2
Denka Black Production Example 3
HC-198 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 Average thickness of coating film (mm) 143 165 343 130 254 597 180 244 455 Coating film density (g / cm ³ ) 1.58 1.54 1.55 1.59 1.52 1.51 1.62 1.63 1.61 division Comparative Manufacturing Example Comparative Preparation Example 1
Denka Black Comparative Production Example 2
HC-198 - 1-1 1-2 1-3 2-1 2-2 2-3 - - - Average thickness of coating film (mm) 128 253 593 171 243 456 - - - Coating film density (g / cm ³ ) 0.075 0.078 0.077 6.3 6.2 6.1

According to Table 3 and FIG. 3, it can be seen that the dispersion of the surface thickness is relatively large in the case of Production Example 1, because the carbon-based powder of Production Example 1 has a low density, so that the powder is separated from the coating layer, It is not easy to control the thickness. Also, Denka Black, which is a carbon-based powder of Production Example 2, was small in powder primary particles, and the coating film containing the same could be agglomerated, resulting in irregularities. The carbon-based powder of Production Example 2 had a higher density than the carbon-based powder of Production Example 1 and maintained the coating layer, and it was confirmed that the coagulated powder increased the coating layer. HC-198, which is a carbon-based powder of Production Example 3, has a relatively large powder density and a large particle size, and the coating layer is formed relatively well and the scattering degree is small when the thickness is measured. Further, in the case of Production Example 2 (Denka Black), it was judged that the surface of the coating layer was not uniform due to agglomeration of powder particles during curing.

On the other hand, also in the case of the carbon-based powder of Comparative Production Example 1, the average particle size and density were lower than those of Production Example 1 and Production Example 2, so that the coating film coagulated to cause irregularities. In Comparative Production Example 2, It is confirmed that the surface of the coating layer is formed unclearly because it is larger than necessary than the powder density and the particle size.

Experimental Example 3. Measurement of magnetic field reduction rate for a magnetic film shielding coating

In order to confirm the magnetic field reduction rate (%) according to the increase of the thickness of the coating film to the average magnetic field value (mG) before the formation of the respective coating films in Production Examples 1 to 3 and Comparative Production Examples 1 and 2, The magnetic field measurement instrument was put on and the change was observed. The magnetic field of the sample according to the present invention was measured after applying the magnetic field measuring apparatus of 65 V and fixing the reference magnetic field on which none was placed at an average of 5 mG. The measuring instrument was a magnetic field measuring device of a very low frequency range and GTM-190 manufactured by TENMARS Co., Ltd. was used. Table 4 shows the specifications of the equipment used. The results are shown in FIG. 4 and Table 5.

division Technical Specifications Specification value Production Examples 1 to 3
And
Comparative Production Examples 1 to 2 Detector type Low frequency magnetic field 3 axes (X, Y, Z) Measuring range 0.02 to 2000 mG Measurement frequency band 50 to 60 Hz Sample extraction time 6 sec

division Coating thickness Average magnetic field (mG) Magnetic field reduction rate (%) Standard Deviation Production Example 1
Super-P - 0 탆 5.025 0.0 0.106 1-1 143 μm 4.495 10.5 0.050 1-2 165 탆 4.480 10.8 0.057 1-3 343 탆 4.175 16.9 0.120 Production Example 2
Denka Black - 0 탆 5.025 0.0 0.106 2-1 130 탆 4.380 12.8 0.085 2-2 254 탆 4.195 16.5 0.035 2-3 597 ㎛ 4.120 18.0 0.071 Production Example 3
HC-198 - 0 탆 5.025 0.0 0.106 3-1 180 탆 4.070 19.0 0.170 3-2 244 탆 3.950 21.4 0.099 3-3 455 탆 3.100 38.3 0.057 Comparative Preparation Example 1
Super-P - 0 탆 5.025 0.0 0.106 1-1 130 탆 3.130 8.1 0.043 1-2 254 탆 3.042 10.1 0.017 1-3 597 ㎛ 3.019 11.3 0.042 Comparative Production Example 2
Denka Black - 0 탆 5.025 0.0 0.106 2-1 180 탆 3.007 10.2 0.045 2-2 244 탆 2.860 12.1 0.031 2-3 455 탆 2.074 19.0 0.021

It was confirmed that the shielding materials of Production Examples 1 to 3 according to the present invention had the effect of reducing the magnetic field in the extremely low frequency region by including the carbon-based powder, and the possibility of magnetic shielding of the carbon material was confirmed. In this case, it was confirmed that the magnetic field decreased as the thickness of the coating film increased. Among them, it was confirmed that the specimen coated with the natural graphite HC-198, the carbon-based powder of Production Example 3, exhibited the best magnetic shielding efficiency.

The shielding materials of Comparative Production Examples 1 and 2 contain the carbon-based powder, but when the density and the average particle size of the carbon particles are too small or too large, the shielding efficiency is relatively higher than that of the shielding materials of Production Examples 1 to 3 of the present invention .

More specifically, in the case of the shielding material using the coating agent of Production Example 3 (using HC-198), the magnetic fields decreased by 4.07 mG, 4.04 mG and 3.10 mG, respectively, Reduction rate. This indicates that the coating of Preparation Example 3 was easier than that of the other specimens because the particles did not aggregate well. The magnetic field reduction rate was measured to be lower than that of Production Example 3 (HC-198) in Production Example 1 (Super-P) and Production Example 2 (Denka Black) The powder was found to fall off from the coating layer before curing and it was judged that the thickness of the coating layer was not easily controlled and that the magnetic field reduction rate was low. This was also confirmed by Comparative Production Example 1 and Comparative Production Example 2.

EXPERIMENTAL EXAMPLE 4. Magnetic Field Measurement According to Voltage Application of Coating Film for Magnetic Field Shielding

The magnetic fields of the coating films containing the magnetic shielding coatings of Production Examples 1 to 3 and Comparative Production Examples 1 to 6 according to the present invention were measured and the results are shown in Table 6 and FIG.

As can be seen from FIG. 6, in the case of Production Examples 1 to 3, the magnetic field was stably measured with a small scattering degree in the thickness measurement, and it was confirmed that the magnetic field was proportionally increased in proportion to the applied voltage However, in the case of Comparative Production Examples 1 to 2, the magnetic field was relatively increased even at the same applied voltage.

division Applied voltage
(V) magnetic field
(mG) Applied voltage
(V) magnetic field
(mG) Applied voltage
(V) magnetic field
(mG) Manufacturing example One 2 3 0 0 0 0 0 0 20 1.9 20 1.9 20 1.6 40 2.8 40 2.9 40 2.6 60 4.7 60 4.8 60 4.4 80 6.5 80 6.7 80 6.3 100 8.5 100 8.7 100 8.2 Comparative Manufacturing Example One 2 - 0 0 0 0 - - 20 3.6 20 3.8 - - 40 7.5 40 7.7 - - 60 9.7 60 9.9 - - 80 - 80 - - - 100 - 100 - - -

As shown in Table 6, in Production Examples 1 to 3, magnetic fields were measured by electrically connecting both ends to a coating film and applying a high voltage stepwise. As a result, it was confirmed that the magnetic field value was proportionally increased, It was confirmed that the coating films of Comparative Production Examples 1 to 2 had a rapid magnetic field at the same voltage.

Experimental Example 5. Comparison of Physical Properties of Coating Film for Magnetic Field Shielding

Each of the coatings prepared in Examples 1 to 3 and Comparative Examples 1 and 2 was subjected to the physical properties test according to the following prescribed test methods, and the results are shown in Table 7 below.

1. Adhesion test

Material adhesion tests were measured for plastic materials ABS, PC, ABS-PC. (Cross Tape Method, 1 mm / 1 mm, 100/100) was performed after 20 탆 dry coating with a spray coating (spraying pressure 4 kgf / cm 2) and drying at 60 to 20 minutes.

?: 100/100,?: 99/100 - 90/100

?: 90/100 - 80/100, 占: 80/100 or less

2. Humidity Environmental Test

The moisture resistance of the film was measured at 85, 85% R.H. after 7 days, and the resistance value was measured with a resistance meter (Lowresta-GP).

◎: Within ± 5% of existing resistance value, ○: Within ± 20% of existing resistance value

△: Within ± 30% of existing resistance value, ×: Within ± 40% of existing resistance value

3. Storage stability test

When the coating agent was allowed to stand at 60 to 168 hours, the state of sedimentation was measured. The sedimentation state was measured by visual determination.

⊚: Excellent, ∘: Good

?: Normal, X: Bad

4. Resistance measurement test

The coating material was applied to the plastic material (dry film: 25 m) and the resistance value was measured with a resistance meter.

?: Resistance value 0.015 Ohm / Sq or less,?: Resistance value 0.015-0.1 Ohm / Sq

△: Resistance value 0.1 - 2.0 Ohm / Sq, ×: Resistance value 2.0 Ohm / Sq or more

division Adhesion test Moisture resistance test Storage stability test Resistance value measurement test  Example 1 ◎ ○ ○ ○  Example 2 ◎ ◎ ○ ◎  Example 3 ◎ ◎ ○ ◎  Comparative Example 1 ○ △ △ ×  Comparative Example 2 ○ △ △ ×

As shown in Table 7, the coating agents of Examples 1 to 3 exhibited relatively better physical properties than those of Comparative Examples 1 and 2, and exhibited a very stable shielding efficiency due to a small amount of change in physical properties in the resistance value and moisture resistance test .

Claims (9)

Conductor;
An insulating film provided on an upper surface of the conductor; And
A coating film for shielding a magnetic field formed on the upper surface of the insulating film and formed by curing a composition comprising carbon black and a binder solution; / RTI >
The carbon black preferably has an average particle size of 15 to 45 μm and an average density of 1.5 to 2.0 g / cm ³ ,
Wherein the binder solution comprises an organic resin,
The coating film for magnetic field shielding has a thickness of 450 to 500 mu m,
And a magnetic field reduction rate of 50 to 60 Hz is 35 to 40%.
The method according to claim 1,
Wherein the composition comprises 5 to 20 parts by weight of carbon black per 100 parts by weight of the binder solution.
delete The method according to claim 1,
Wherein the organic resin comprises at least one member selected from the group consisting of a lacquer resin, an epoxy resin and a phenol resin.
delete delete A first step of forming an insulating film by coating and curing an upper surface of the conductor with an organic resin; And
A second step of coating a coating material containing a composition containing carbon black and a binder solution on one surface of the insulating film and then curing the coating material to form a coating film for shielding a magnetic field at an extremely low frequency; Lt; / RTI >
The carbon black preferably has an average particle size of 15 to 45 μm and an average density of 1.5 to 2.0 g / cm ³ ,
Wherein the binder solution comprises an organic resin,
The coating film for magnetic field shielding has a thickness of 450 to 500 mu m,
And a magnetic field reduction rate of 50 to 60 Hz is 35 to 40%.
8. The method of claim 7,
Wherein the curing in the second step is performed at 20 to 150 DEG C for 30 minutes to 100 minutes.
8. The method of claim 7,
Wherein the thickness of the insulating film is 20 to 50 占 퐉.

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