KR20210096574A - Emi shielding coating composition for electronic component of automobile - Google Patents

Abstract

The present invention relates to an electromagnetic wave shielding coating composition for vehicle electronic components including a silicone-based resin and an inorganic filler, and specifically, to an electromagnetic wave shielding coating composition for vehicle electronic components and a method for manufacturing the same, wherein the inorganic filler includes expanded graphite and carbon nanotubes.

Description

EMI SHIELDING COATING COMPOSITION FOR ELECTRONIC COMPONENT OF AUTOMOBILE TECHNICAL FIELD

The present invention relates to an electromagnetic wave shielding coating composition for automotive electronic parts and a method for manufacturing the same, while maintaining electromagnetic wave shielding performance using an inorganic filler, reducing manufacturing cost and reducing the weight of the electromagnetic shielding coating composition for automotive electronic parts and a method for manufacturing the same it's about

Following the expansion of electric vehicles, hydrogen cars, and hybrid cars, the spread of smart cars centered on unmanned/autonomous vehicles is imminent, and the added value of the automobile market is increasing in line with the commercial expansion of IoT (Internet of Things) and 5G technologies. It is a trend leading to

In addition, as personalized technology appears and its application area expands, various technologies for the purpose of convenience and stability in our lives are being applied. ) is being used, and the growth expectation of electronic parts is projected from 2015 (31.5%) to 2030 (50% or more), and it is expected to be used more actively in the future.

In the case of electronic parts adopted for safety and convenience in the automobile industry, they are combined into various units, and malfunctions of automobile parts due to electromagnetic waves emitted from each electric part unit may develop into a safety accident. There is also a significant increase in the risk of human casualties caused by , etc.

Moreover, since electromagnetic waves are known to adversely affect the human body through thermal and non-thermal actions, the demand for technology capable of effectively blocking electromagnetic waves emitted from electronic components is increasing with the increase of electronic components.

Accordingly, the need for the development of a high-performance electromagnetic shielding (EMI shielding) coating agent as a method to minimize the malfunction caused by electromagnetic waves of electronic components has emerged.

On the other hand, research and development to improve fuel efficiency in the automobile field in terms of eco-friendliness, air pollution improvement, and energy saving are more actively taking place recently. Electromagnetic wave shielding coatings, which are indispensable for electric components constituting automobiles, can secure excellent electric wave shielding performance by including metallic fillers. There was a problem with increasing.

Accordingly, there is an urgent need to develop a new coating agent having an excellent electromagnetic wave shielding effect while trying to reduce the weight of the vehicle in terms of improving the fuel efficiency of the vehicle.

Republic of Korea Patent Registration No. 10-0850007 (2008.08.01) Republic of Korea Patent Publication No. 2004-0099821 (2004.12.02) Republic of Korea Patent Publication No. 2017-0071896 (2017.06.26)

An object of the present invention is to provide a high-shielding composition that can be applied to automotive electronic parts, can shield electromagnetic waves, and can be coated on the surface of electronic parts.

An object of the present invention is to provide a method for manufacturing a high-shielding composition that can be applied to automotive electrical components, can shield electromagnetic waves, and can be coated on the surface of electrical components.

The present invention also provides an anti-electromagnetic wave shielding coating composition for automotive electronic parts that has an excellent electromagnetic wave shielding effect while including an inorganic filler, and thus the manufacturing cost is reduced, as compared to the existing electromagnetic wave shielding coating composition containing a metallic filler aim to do

The present invention provides an electromagnetic wave shielding coating composition for automotive electrical components that can reduce the weight of a coating agent and thus lighten a vehicle to which the coating agent is applied by using an inorganic filler such as expanded graphite instead of a metallic filler.

Electromagnetic wave shielding coating composition for automobile electric parts comprising a silicone-based resin and an inorganic filler according to the present invention for solving the above problems, the inorganic filler is expanded graphite and carbon nanotubes (Carbon nano tube) include

In the present invention, the silicone-based resin may be a polydimethyl siloxane (PDMS) resin.

In the present invention, the inorganic filler may be included in an amount of 1 to 20% by weight based on the total weight.

In the present invention, the expanded graphite may have an average particle size of 20 to 100 μm (micrometer).

In the present invention, the expanded graphite and the carbon nanotubes may be included in a weight ratio of 1: 1 to 3.

In the present invention, the electromagnetic wave shielding coating composition for automotive electrical components may further include a silane coupling agent.

The present invention also provides a method for producing the electromagnetic wave shielding coating composition for automotive electrical components described above, comprising the steps of: (a) preparing a mixture by mixing a silicone-based resin, an inorganic filler and a curing agent; and (b) removing foam in the mixture; and (c) applying and curing the mixture; It provides a method of manufacturing an electromagnetic wave shielding coating composition for automotive electrical components comprising a.

In the present invention, step (a) may be mixing for 0.5 to 5 minutes at a speed of 1500 to 2500 rpm.

In the present invention, the step (b) may be stirring at a speed of 1800 to 2700 rpm for 0.5 to 5 minutes.

In the present invention, the step (c) may be to maintain the temperature of 50 to 70 ℃ after applying the mixture and to cure for 1 to 5 days.

In the present invention, the inorganic filler of step (a) comprises the steps of (a-1) mixing ethanol, a silane coupling agent, and acetic acid at room temperature for 3 to 7 minutes; (a-2) mixing the mixture of step (a-1) with the inorganic filler and then mixing at room temperature for 25 to 35 minutes; and (a-3) centrifuging the inorganic filler of step (a-2) for 5 to 15 minutes and then drying the inorganic filler at a temperature of 70 to 90° C. for 5 to 10 hours; It may be that the pre-processing process through

The electromagnetic wave shielding coating composition for automotive electronic components according to the present invention is excellent in the electromagnetic wave shielding effect.

In the present invention, the electromagnetic wave shielding coating composition for automotive electrical components has the effect of being able to coat the surface of the automotive electrical components.

The present invention also has the effect of reducing the manufacturing cost while having an equivalent electromagnetic wave shielding effect, compared to the conventional electric wave shielding coating composition comprising a metallic filler.

The electromagnetic wave shielding coating composition for automotive electrical components according to the present invention includes an inorganic filler instead of a metallic filler, and thus has an advantage of being lighter compared to the equivalent electromagnetic wave shielding effect. Therefore, it has the advantage of contributing to the weight reduction of the vehicle to which it is applied.

1 is a photograph of specimen samples of Comparative Examples and Examples prepared in Experimental Example 1. FIG.
2 is a graph showing the mechanical properties test results of the specimen of Comparative Example to which graphite was added in Experimental Example 1. Referring to FIG.
3 is a graph showing the mechanical properties test results of the specimen of Comparative Example to which the expanded graphite having a particle size of 140 μm was added in Experimental Example 1. Referring to FIG.
4 is a graph showing the mechanical properties test results of the specimen of Comparative Example to which the expanded graphite having a particle size of 50 μm was added in Experimental Example 1. Referring to FIG.
5 is a graph showing the mechanical properties test results of the specimen of Comparative Example to which the expanded graphite having a particle size of 8 μm was added in Experimental Example 1;
6 is a graph showing the mechanical properties test results of the specimen of Example 1 to which the expanded graphite having a particle size of 50 μm and carbon nanotubes were added in Experimental Example 1. Referring to FIG.
7 is a comparative graph showing the mechanical properties test results of Experimental Example 1.
8 is a graph showing the 180° peel test [left] and probe tack test [right] results for each filler particle size of Experimental Example 2.
9 is a process flow chart showing a method of manufacturing a vehicle electric wave shielding coating composition according to the present invention.
10 is a test report showing the electromagnetic wave shielding effect of the coating composition according to the present invention.

Hereinafter, each configuration of the present invention will be described in more detail so that those of ordinary skill in the art to which the present invention pertains can easily carry out, but this is only an example, and the scope of the present invention is defined by the following contents not limited.

The electromagnetic wave shielding coating composition for automotive electronic components according to the present invention includes a silicone-based resin and an inorganic filler, and the inorganic filler is included in an amount of 1 to 20% by weight based on the total weight.

The automotive electronic component refers to all electrical/electronic components included in the vehicle. When a current flows and operates in a device including the electrical/electronic component, electromagnetic waves are emitted.

Electromagnetic waves are also called electromagnetic waves, and refer to waves composed of an electric field and a magnetic field. When an electric current flows through an electric component, a magnetic field and an electric field are formed, which are emitted to the outside in the form of energy.

Since the electromagnetic waves generated in this way can affect other electronic devices or the human body, various technologies are being developed to block the dangers of electromagnetic waves in a modern society that uses numerous electronic components.

The state in which electromagnetic waves are emitted to interfere with other electronic devices is called electromagnetic interference. The device may malfunction.

Malfunction of electronic devices due to electromagnetic waves can cause great damage in electronic devices that can lead to personal accidents, such as medical devices or automobiles. is being developed

In addition, electromagnetic waves of strong intensity can have a harmful effect on the human body, so electromagnetic wave human protection standards are prepared. It has also been reported that it can affect the

The World Health Organization (WHO)-affiliated International Agency for Research on Cancer (IARC) classifies cell phone electromagnetic waves as 2B (a group that can cause cancer, usually there is limited evidence for carcinogenicity to humans, and there is insufficient evidence of carcinogenicity in animal experiments) It is classified as a gas and is considered to have the same level of toxicity as lead and gasoline engine gas.

Accordingly, the present invention prevents malfunctions of a vehicle that may occur due to interference caused by electromagnetic wave emission between electronic components in a vehicle having numerous electronic components built-in, and prevents harmful effects of electromagnetic waves on users riding in the vehicle. To prevent this, it relates to a technology for effectively preventing the emission of electromagnetic waves by coating the surface of electric parts of automobiles.

In the present invention, the silicone-based resin is not particularly limited as long as it has an affinity for the surface of automotive electronic components, and various types are preferably used.

Preferably, polydimethyl siloxane (PDMS) resin may be used. By including the material, it is possible to manufacture an electromagnetic wave shielding material exhibiting excellent bending strength and tensile strength.

In the present invention, the inorganic filler is not particularly limited as long as it is used as an inorganic filler in the relevant technical field and can be used in various ways. For example, fillers made of inorganic materials such as carbon-based fillers and metal oxide fillers can be used. .

Preferably, it may be a carbon-based filler, for example, a mixture of expanded graphite (Expanded graphite) and carbon nano tube (Carbon nano tube) may be used.

The carbon-based filler has conductivity and absorbs electromagnetic waves emitted from automotive electronic parts to be absorbed into the coating layer, or to be removed by being conducted to the surface coating layer of automotive electronic parts instead of being emitted to the outside.

The expanded graphite is also referred to as graphite oxide, and refers to the expansion of graphite by chemical substances by putting train chemicals such as acids, alkalis and salts in natural impression graphite.

In the present invention, by including expanded graphite in the electromagnetic wave shielding coating composition for automotive electrical components, the emission of electromagnetic waves is prevented, and further, due to the flame retardant properties of expanded graphite, it is possible to prevent deterioration of parts due to heat generated during operation of electrical components. have a possible effect.

Expanded graphite, a carbon-based material, is attracting attention as a new material that is expected to be applied in fields requiring high-functional composite materials because of its high thermal conductivity, excellent mechanical properties, and light weight. It is reported that the thermal conductivity of the composite material to which the expanded graphite is applied depends on the degree of exfoliation of the expanded graphite, the dispersion state, and the aspect ratio.

When the expanded graphite is used, since dispersion is stably made in the silicone resin, which is the main material, a spray coating method can be applied, which is advantageous in that the coating process can be easily performed.

In the conventional sputtering method, there is a limit to shielding non-semiconductor modules or other electronic components, but according to the spray coating method, vertical surface coating is also possible by adjusting the spray angle of the nozzle, so that it can be applied to various parts.

In particular, compared to the conventional sputtering method, according to the spray coating method, the equipment investment cost is reduced by about 1/4, and the production speed can be improved by about 40%, which is advantageous in terms of depreciation cost and productivity improvement.

Meanwhile, the carbon nanotube is a carbon material having a tube structure made by forming a layer of graphite made of carbon and rolling graphene, which is a hexagonal honeycomb planar structure, into a nano-sized tube, and has a fiber shape.

In the present invention, it is characterized in that it includes an inorganic filler in the form of a mixture including carbon nanotubes together with expanded graphite. The carbon nanotubes are configured in the form of fibers, have flexible properties, and have excellent conductivity.

The inorganic filler may be included in an amount of 1 to 20% by weight, based on the total weight of the composition. Preferably, it may be included in an amount of 5 to 10% by weight.

This is a numerical value for achieving the object of the present invention, and when it is included in a content lower than the numerical value, the electromagnetic wave shielding effect may be insufficient, and when it is added in excess than the content, the viscosity is large, so it is not suitable for application as a coating agent. Alternatively, there is a problem in that the coating force and adhesion to the surface of the electrical component are deteriorated, and the manufacturing cost of the composition is increased, which may cause a problem in that the productivity is lowered.

The expanded graphite may have an average particle size of 20 to 100 μm (micrometer). More preferably, a thing of 40-60 micrometers (micrometer) can be used.

When the particle size is larger than the above range, there is a problem that the uniformity (uniform distribution) is lowered, and when the particle size is lower than the above range, there is a problem that aggregation of particles may occur.

The inorganic filler may include the expanded graphite and the carbon nanotubes in a weight ratio of 1: 1 to 3.

When the ratio of carbon nanotubes is higher than the ratio, there may be a problem that the uniformity (uniform distribution) of particles is lowered, and when the ratio of carbon nanotubes is decreased than the ratio, conductivity performance is lowered there may be

The electromagnetic wave shielding coating composition for automotive electrical components according to the present invention is aged to improve adhesion as necessary, or to prevent aging of the resin due to heat generated on the surface of the electrical components and aging of the resin over time An inhibitor may be added, or an additional adhesive component may be further included to improve adhesion on the surface of the electrical component.

In addition, an antifoaming agent for removing air bubbles in the coating agent, a dispersing agent for improving the dispersibility of the inorganic filler in the composition, and a flame retardant or flame retardant for preventing ignition due to heat generated in electrical components may be additionally added.

The above additional components can be variously added within a range that does not impair the purpose of the present invention, and the content thereof is preferably added in an amount of 0.01 to 10% by weight based on the total weight of the composition.

When added in a small amount than the above content, even if the component is added, there is a useless problem because it does not exhibit its function. There is a problem in that the coating has difficult physical properties.

For example, the electric vehicle shielding coating composition for automotive electrical components according to the present invention may further include a silane coupling agent.

The silane coupling agent is a material known to improve the adhesion between inorganic materials and organic materials. When a silicone-based resin and an inorganic filler are included in the coating composition as in the present invention, miscibility is further improved, and the surface of electrical components It has the effect of further improving the adhesion and coating power.

The electromagnetic wave shielding coating composition for automotive electrical components according to the present invention may have a viscosity of 1 to 500 cps (centipoise), and the electromagnetic wave shielding rate of the coating film formed on the surface of the electronic component using this is 20 dB or more (ASTM D4935) standard) can be

The electromagnetic wave shielding coating composition for automotive electronic parts according to the present invention can be applied to various parts regardless of the type of parts, and has the advantage that it can be applied even if the surface on which the coating is applied is plastic or non-metallic materials such as metals and semiconductors. .

On the other hand, the manufacturing method of the electromagnetic wave shielding coating composition for automotive electrical components according to the present invention comprises the steps of (a) preparing a mixture by mixing a silicone-based resin, an inorganic filler and a curing agent, and (b) removing bubbles in the mixture and ( c) applying and curing the mixture.

After the silicone-based resin and the inorganic filler are put in a mixer, a curing agent is added and mixed, and the foam formed in the mixture is removed.

Specifically, step (a) may be mixing for 0.5 to 5 minutes at a speed of 1500 to 2500 rpm. More preferably, it may be mixing for 1 to 3 minutes at a speed of 1800 to 2200 rpm.

At this time, the mixing process may not be performed only once, but may be performed two or more times, and more preferably, may be repeated 2 to 4 times. When repeated, the mixture can be mixed more uniformly.

In the case of mixing faster than the speed in the mixing process, there may be a problem that the mixture is mixed non-uniformly, resulting in poor uniformity, and when mixing slower than the speed, excessive bubbles may be included in the mixture. there is.

Here, the curing agent may include organic peroxide, isocyanate, azo, amine, imidazole, and the like. However, the present invention is not limited thereto, and various materials capable of curing the electromagnetic wave shielding coating composition for automotive electronic components may be used.

The step of removing the foam may be performed by various methods such as raising the temperature, adding an anti-foaming agent, and resting, in order to prevent deterioration and aging of the coating film formed using the coating composition by removing the foam.

When a coating film is formed in a state containing bubbles, the coating composition with low viscosity hardens and forms a thin film. Bubbles or air bubbles act as defects that weaken the strength of the coating film, and the durability of the coating film is reduced. may occur.

Preferably, the step (b) may be stirring at a speed of 1800 to 2700 rpm for 0.5 to 5 minutes. More preferably, it may be stirred for 1 to 3 minutes at a speed of 2000 to 2500 rpm.

In the case of stirring at a speed faster than the above speed, there may be a problem that non-uniform mixing of components in the composition may occur, and if stirring at a speed slower than the above speed, there may be a problem that bubbles are not sufficiently removed there is.

In step (c), the mixture may be cured for 1 to 5 days while maintaining a temperature of 50 to 70° C. after applying the mixture.

More preferably, it may be cured for 2 to 4 days while maintaining a temperature of 55 to 65 ℃.

When carried out at a temperature higher than the above temperature, there is a problem in that the viscosity increases or physical properties such as cracks are changed, and when it is performed at a temperature lower than the above temperature, there may be a problem that is not sufficiently cured.

On the other hand, the electromagnetic wave shielding coating composition for automotive electrical components according to the present invention may further include a silane coupling agent, and preferably, may be added in the form of coating on the surface of the inorganic filler. However, this is only an example, and even if it is not added in a coated form, it will be considered that it falls within the scope of the present invention within a range that can satisfy the function of the silane coupling agent.

Accordingly, in the method of manufacturing the electromagnetic wave shielding coating composition for automotive electrical components, a pretreatment process of coating the inorganic filler with the silane coupling agent may be further performed.

Specifically, the inorganic filler of step (a) is (a-1) a step of mixing ethanol, a silane coupling agent, and acetic acid at room temperature for 3 to 7 minutes, (a-2) the mixture of step (a-1) After mixing the inorganic filler with the step of mixing at room temperature for 25 to 35 minutes, and (a-3) centrifuging the inorganic filler of step (a-2) for 5 to 15 minutes, the temperature of 70 to 90 ℃ By performing a pretreatment process through a step of maintaining and drying for 5 to 10 hours, it may be composed of an inorganic filler coated with a silane coupling agent.

In step (a-1), acetic acid may be added in an amount of 1 to 5% by volume, more preferably, 1.5 to 2.5% by volume based on the total volume of the mixture.

When it is added in excess of the above content, there may be a problem in that mechanical properties are lowered, and when added in a small amount than the content, there may be a problem in that the binding force (adhesion force) is lowered.

In addition, the mixing time in step (a-1) may be performed for 2 to 6 minutes. When mixing longer than the above time, there is a problem that the viscosity of the mixed solution increases, and when mixing shorter than the above time, there may be a problem that sufficient mixing does not occur.

Preferably, the silane coupling agent mixture and the inorganic filler in step (a-2) may be mixed for 27 to 33 minutes.

When mixing longer than the above time, there may be a problem that mechanical properties are lowered, and when mixing shorter than the above time, there is a problem that it is difficult to form a uniform coating layer because the mixture is not sufficiently wetted on the surface of the inorganic filler .

Finally, in step (a-3), the mixture is stirred through a centrifuge for 7 to 12 minutes to separate the coated inorganic filler, and the coated filler is completed by drying at a temperature of 75 to 85° C. for 7 to 9 hours. .

The inorganic filler that has undergone such a pre-treatment process is manufactured into an electromagnetic wave shielding coating composition for automotive electronic components through a series of processes described above.

The electromagnetic wave shielding coating composition for automotive electrical components prepared according to the above process is applied to the surface of automotive electrical components and then cured to form a coating film, thereby obtaining an electromagnetic wave shielding effect.

Hereinafter, the invention will be described in more detail based on examples, but this is only an example, and the scope of the present invention is not limited thereto and various modifications are possible.

Experimental Example 1 - Mechanical properties test according to filler type and content

After adding a curing agent and an inorganic filler to PDMS, mixing at a speed of 2000 rpm for 1 minute, this was repeated 3 times to prepare a mixture. Thereafter, a process (Defoam) of removing air bubbles by further stirring at a speed of 2200 rpm for 1 minute was performed.

The prepared mixture was put into a mold for a specimen to form a specimen for testing mechanical properties, cast, and cured at a temperature of 60° C. for 3 days to prepare a specimen.

The composition of the inorganic filler is shown in Table 1, and the tensile test test results for each specimen are shown in Table 2 and FIGS. 2 to 6 .

Sample classification Silicon (S) Filler PDMS
(g) Hardener
(g) Graphite
(g) Expanded
graphite
140μm
(g) Expanded
graphite
50μm
(g) Expanded
graphite
8μm
(g) EG(50um)+CNT
(g) S-Base 15.0 1.5 - - - - - S-G-1wt% 14.9 1.4 0.17 - - - - S-G-3wt% 14.6 1.4 0.50 - - - - S-G-5wt% 14.3 1.4 0.85 - - - - S-G-10wt% 13.6 1.3 1.62 - - - - S-G-20wt% 12.1 1.2 3.28 - - - - S-EG140-1wt% 14.9 1.4 - 0.17 - - - S-EG140-3wt% 14.7 1.4 - 0.49 - - - S-EG140-5wt% 14.3 1.4 - 0.83 - - - S-EG140-10wt% 13.5 1.3 - 1.59 - - - S-EG140-20wt% 12.0 1.2 - 3.27 - - - S-EG50-1wt% 14.9 1.4 - - 0.16 - - S-EG50-3wt% 14.6 1.4 - - 0.48 - - S-EG50-5wt% 14.2 1.4 - - 0.85 - - S-EG50-10wt% 13.6 1.3 - - 1.59 - - S-EG50-20wt% 12.0 1.2 - - 3.20 - - S-EG8-1wt% 14.8 1.4 - - - 0.16 - S-EG8-3wt% 14.5 1.4 - - - 0.51 - S-EG8-5wt% 14.2 1.4 - - - 0.83 - S-EG8-10wt% 13.5 1.3 - - - 1.62 - S-EG8-20wt% 12.1 1.2 - - - 3.21 - S-EG/C-1wt% 14.8 1.4 - - - - 0.17 S-EG/C-3wt% 14.6 1.4 - - - - 0.50 S-EG/C-5wt% 14.3 1.4 - - - - 0.84 S-EG/C-10wt% 13.5 1.3 - - - - 1.63 S-EG/C-20wt% 12.0 1.2 - - - - 3.21

Exp. Silicone Polymer/Filler Composite Tensile experiment PDMS
(g) Hardener
(g) filler
(g) Modulus
(Mpa) stress
(Mpa) strain
(%) S-Base 15.0 1.5 - 0.15 0.43 255.00 S-G-1wt% 14.9 1.4 0.17 0.11 0.41 231.00 S-G-3wt% 14.6 1.4 0.50 0.19 0.46 350.00 S-G-5wt% 14.3 1.4 0.85 0.10 0.35 180.00 S-G-10wt% 13.6 1.3 1.62 0.14 0.32 219.00 S-G-20wt% 12.1 1.2 3.28 0.24 0.28 185.00 S-EG140-1wt% 14.9 1.4 0.17 0.11 0.40 174.10 S-EG140-3wt% 14.7 1.4 0.49 0.13 0.33 171.00 S-EG140-5wt% 14.3 1.4 0.83 0.13 0.32 171.80 S-EG140-10wt% 13.5 1.3 1.59 0.27 0.21 127.90 S-EG140-20wt% 12.0 1.2 3.27 0.41 0.14 98.50 S-EG50-1wt% 14.9 1.4 0.16 0.11 0.38 173.00 S-EG50-3wt% 14.6 1.4 0.48 0.11 0.38 185.00 S-EG50-5wt% 14.2 1.4 0.85 0.12 0.35 201.00 S-EG50-10wt% 13.6 1.3 1.59 0.17 0.31 197.00 S-EG50-20wt% 12.0 1.2 3.20 0.39 0.24 141.00 S-EG8-1wt% 14.8 1.4 0.16 0.11 0.35 169.00 S-EG8-3wt% 14.5 1.4 0.51 0.12 0.37 186.00 S-EG8-5wt% 14.2 1.4 0.83 0.14 0.32 167.00 S-EG8-10wt% 13.5 1.3 1.62 0.19 0.32 165.00 S-EG8-20wt% 12.1 1.2 3.21 0.31 0.37 131.00 S-Base 15.0 1.5 - 0.10 0.44 262.00 S-EG/C-1wt% 14.8 1.4 0.17 0.11 0.36 177.00 S-EG/C-3wt% 14.6 1.4 0.50 0.20 0.42 242.00 S-EG/C-5wt% 14.3 1.4 0.84 0.27 0.27 113.00 S-EG/C-10wt% 13.5 1.3 1.63 0.61 0.36 114.00 S-EG/C-20wt% 12.0 1.2 3.21 0.90 0.25 91.20

(G: Graphite, EG140: 140 μm particle diameter expanded graphite, EG/C: 50 μm particle diameter expanded graphite + carbon nanotube 1:1 weight ratio mixture)

Experimental Example 2 - Adhesion test according to the addition of a silane coupling agent

Among the above results, for a specimen containing expanded graphite and carbon nanotubes as fillers, an adhesive specimen was prepared by adding a silane coupling agent, and the adhesive properties of the heat dissipating silicone adhesive were investigated using a 180° peel test and a probe tack test. .

For the 180° peel test, an adhesive specimen having a length of 200 mm and a thickness of 25 mm was attached to the SUS, and a 2 kg rubber roller was reciprocally attached to each other. After waiting for 20 minutes, it was measured at a test speed of 300 mm/min.

The probe tack test was measured according to ASTM D2979. Tack strength was measured a total of 5 times or more, and the average value of the remainder except for the maximum and minimum values was obtained.

The results of each measurement value are shown in Table 3 and FIG. 8 .

Sample mixed filler
Particle size (μm) 180° Peel Strength
(gf/25mm) Probe Tack Strength
(gf) EG/CNT-1 8 45.8 201.5 EG/CNT-2 50 34.8 165.4 EG/CNT-3 140 14.3 87.4

Referring to Table 2, it can be seen that the heat transfer properties of the EG/CNT mixed filler are superior to that of using only EG (Expanded Graphite) as the filler.

In particular, the measurement modulus of the 20wt% EG/CNT specimen is the highest, so it is expected to be effectively applicable to the aspect of dimensional stabilization (lower deformability).

On the other hand, since the values of stress and strain are lowered, 20wt% was estimated as the optimal ratio to secure basic mechanical properties (stress/strain) (if the stress and strain values are too low, damage due to external forces such as vibration) problems may arise).

For the application of electric vehicle parts, it is good to have a high filler content in terms of electromagnetic wave shielding.

According to Table 3, when expanded graphite and carbon nanotubes having an average particle size of 8 μm were used together as inorganic fillers, the best adhesion results were obtained, and expanded graphite and carbon nanotubes having an average particle size of 50 μm were used together It can be seen that the adhesive strength is almost the same even in the case of

Accordingly, it can be confirmed that the coating composition comprising expanded graphite having an average particle size of 50 μm and carbon nanotubes having excellent mechanical properties and excellent adhesion as an inorganic filler is most suitable for coating on automotive electronic parts.

Experimental Example 3 - Electromagnetic wave shielding effect confirmation experiment

An electromagnetic wave shielding effect evaluation experiment was conducted using a coating composition containing expanded graphite having an average particle size of 50 μm and carbon nanotubes as inorganic fillers used in Experimental Example 2 above.

The electromagnetic shielding rate evaluation method according to ASTM D4935 was performed, and it was commissioned by the Korea Polymer Testing Laboratory.

10 is a test report showing the electromagnetic wave shielding effect of the coating composition according to the present invention.

Referring to FIG. 10 , it was confirmed that it had an electromagnetic wave shielding rate of 20.2 dB or more, and it was confirmed that the above-described mechanical properties and adhesion were excellent, and the electromagnetic wave shielding effect was excellent, so that it was suitable for use in automotive electronic parts.

Claims (11)

As an electromagnetic wave shielding coating composition for automotive electronic parts comprising a silicone-based resin and an inorganic filler,
The inorganic filler is an electromagnetic wave shielding coating composition for automotive electrical components comprising expanded graphite and carbon nanotubes. According to claim 1,
The silicone-based resin is a polydimethyl siloxane (PDMS) resin, an electromagnetic wave shielding coating composition for automotive electronic components, characterized in that. According to claim 1,
The inorganic filler is an electromagnetic wave shielding coating composition for automotive electrical components, which is included in an amount of 1 to 20% by weight based on the total weight. According to claim 1,
The expanded graphite has an average particle size of 20 to 100 μm (micrometer) in an electromagnetic wave shielding coating composition for automotive electrical components. According to claim 1,
The expanded graphite and the carbon nanotube are included in a weight ratio of 1: 1 to 3, the electromagnetic wave shielding coating composition for automotive electrical components. According to claim 1,
The electromagnetic wave shielding coating composition for automotive electrical components further comprises a silane coupling agent. A method for preparing the electromagnetic wave shielding coating composition for automotive electrical components according to claim 1, comprising:
(a) preparing a mixture by mixing a silicone-based resin, an inorganic filler, and a curing agent; and
(b) removing foam in the mixture; and
(c) applying and curing the mixture;
A method of manufacturing an electromagnetic wave shielding coating composition for automotive electrical components comprising a. 8. The method of claim 7,
The step (a) is a method of manufacturing an electromagnetic wave shielding coating composition for automotive electrical components to be mixed for 0.5 to 5 minutes at a speed of 1500 to 2500 rpm. 8. The method of claim 7,
The step (b) is a method of manufacturing an electromagnetic wave shielding coating composition for automotive electrical components that is stirred at a speed of 1800 to 2700 rpm for 0.5 to 5 minutes. 8. The method of claim 7,
The step (c) is a method of manufacturing an electromagnetic wave shielding coating composition for automotive electrical components that is cured for 1 to 5 days while maintaining a temperature of 50 to 70° C. after applying the mixture. 8. The method of claim 7,
The inorganic filler of step (a) is,
(a-1) mixing ethanol, a silane coupling agent, and acetic acid at room temperature for 3 to 7 minutes;
(a-2) mixing the mixture of step (a-1) with the inorganic filler and then mixing at room temperature for 25 to 35 minutes; and
(a-3) drying the inorganic filler of step (a-2) for 5 to 10 hours while maintaining a temperature of 70 to 90° C. after centrifugation for 5 to 15 minutes;
A method of manufacturing an electromagnetic wave shielding coating composition for automotive electronic parts that has been subjected to a pretreatment process through

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