KR102167063B1 - Composition for preparing electromagnetic wave shielding gasket and electromagnetic wave shielding gasket prepared therefrom - Google Patents

Abstract

Disclosed are a composition for manufacturing an electromagnetic shielding gasket and a gasket for electromagnetic shielding. The disclosed composition for manufacturing a gasket for electromagnetic wave shielding includes 100 parts by weight of a conductive filler, 1 to 15 parts by weight of a silane-based crosslinking agent, and 1 to 10 parts by weight of a solvent, but does not include any silicone resins including thermosetting silicone resins.

Description

Composition for preparing electromagnetic wave shielding gasket and electromagnetic wave shielding gasket prepared therefrom}

Disclosed are a composition for manufacturing an electromagnetic shielding gasket and a gasket for electromagnetic shielding. In more detail, a composition for manufacturing an electromagnetic wave shielding gasket including a silane-based crosslinking agent but not including any silicone resin including a thermosetting silicone resin, and a gasket for electromagnetic wave shielding prepared from the composition for manufacturing an electromagnetic wave shielding gasket are disclosed.

Harmful electromagnetic waves generated from circuits installed inside various electric/electronic and communication devices cause malfunction of the device or interference with radio waves, resulting in lower product performance and shorten product life. Moreover, when electromagnetic waves penetrate into the human body, the temperature of the tissue cells of the living body is increased by the action of heat, thereby causing problems such as weakening the immune function. On the other hand, with the development of electronic circuit integration technology, it became possible to use unit circuits with various functions in a narrow space, but in addition to this, electromagnetic interference (EMI) generated from each circuit between adjacent circuits is an important problem. As a result, there is an increasing demand for products conforming to electromagnetic compatibility (EMC).

In order to satisfy electromagnetic compatibility, electromagnetic wave noise generated from various electric/electronic and communication devices should be reduced as much as possible, and the electromagnetic wave sensitivity of the device itself should be strengthened by reducing the electromagnetic wave sensitivity to external electromagnetic environment. The most important characteristics required for electromagnetic wave compatibility products inserted in various electric/electronic and communication devices are that the electromagnetic wave shielding rate and absorption rate must be large, and the electromagnetic wave compatibility product must be small and thin according to the trend of light, thin and short devices.

Conventional electromagnetic wave absorbers are materials that attenuate radio wave energy or lower the reflected wave below a reference value by using the high-frequency loss characteristics of constituent materials, and are classified into conductive loss materials, dielectric loss materials, magnetic loss materials, and the like according to the materials used. The composite ferrite electromagnetic wave absorber, which is mainly used as an electromagnetic wave absorber, is a mixture of ferrite with a magnetic material such as silicon rubber and plastic as a support material, which is manufactured in a sheet form of about 1 mm and is used for radar reflection prevention in the GHz band. .

In addition, electromagnetic wave shielding materials are generally manufactured in the form of conductive mesh, conductive fiber, conductive rubber, etc. by adding metals (iron, copper, nickel, etc.) to plastic, which shields or reflects electromagnetic waves to avoid direct effects from electromagnetic waves. Although it may be possible, the electromagnetic environment persists, and there is a risk of electric shock in the case of an electromagnetic shielding material in which polyester is plated with copper, nickel, or the like.

In addition, conventional electromagnetic wave shielding and absorbing sheets are coated with soft magnetic metal powder (eg, permalloy, sendust, Fe-Si, Ni-Fe, etc.) on one or both sides of a conductive layer. As an electromagnetic wave shielding and absorbing layer are stacked, there is a limit to efficiently dissipating heat generated from the sheet itself, although the electromagnetic wave shielding and absorbing properties are good.

On the other hand, Korean Patent Laid-Open Publication No. 2004-0033257 discloses “at least one electromagnetic wave absorbing layer in which soft magnetic metal powder is dispersed in a base polymer, and at least one electrically insulating heat conductive layer in which an electrically insulating thermally conductive polymer is dispersed in a base polymer. As an electromagnetic wave absorbing thermal conductive sheet stacked with a layer of, an electrically insulating electromagnetic wave absorbing thermal conductive sheet having an insulation breakdown voltage of 1 KV or more in the thickness direction of the sheet" is described, but this electromagnetic wave absorbing thermal conductive sheet has electromagnetic wave shielding and heat dissipation properties. Insufficient In addition, Japanese Laid-Open Patent Publication No. 2002-076683 discloses a ``electromagnetic wave absorbing heat dissipation sheet composed of a laminated body of an electromagnetic wave absorbing layer and a heat dissipating layer'', but this electromagnetic wave absorbing heat dissipating sheet has unclear electrical insulation and insufficient electromagnetic wave absorption. Do.

An embodiment of the present invention provides a composition for manufacturing an electromagnetic wave shielding gasket that includes a silane-based crosslinking agent, but does not include any silicone resins including thermosetting silicone resins.

Another embodiment of the present invention provides an electromagnetic wave shielding gasket prepared from the composition for manufacturing the electromagnetic wave shielding gasket.

One aspect of the present invention,

It provides a composition for manufacturing an electromagnetic wave shielding gasket including 100 parts by weight of a conductive filler, 1 to 15 parts by weight of a silane-based crosslinking agent, and 1 to 10 parts by weight of a solvent, but not including any silicone resins, including thermosetting silicone resins.

The conductive filler may include dendritic particles.

The conductive filler may include silver having an average particle diameter of 0.5 to 50 μm, copper, nickel, copper coated with silver, nickel coated with silver, graphite coated with silver, glass coated with silver, or a combination thereof. .

The conductive filler is copper coated with silver, and the ratio of the silver and the copper may be 10 to 25 parts by weight to 50 to 60 parts by weight.

The silane-based crosslinking agent may include ketoxime silane.

The ketoxime silane is tetrakis(methylethylketoxime)silane, methyltris(dimethylketoxime)silane, methyltris(methylethylketoxime)silane, ethyltris(methylethylketoxime)silane, methyltris(methylisobutyl) Ketoxime)silane, vinyl tris(methylethylketoxime)silane, bis(ethylmethylketoxime)methoxymethylsilane, or a combination thereof.

The solvent may include a hydrocarbon, a halogenated hydrocarbon, an ester, or a combination thereof.

Another aspect of the invention,

It provides a gasket for electromagnetic wave shielding manufactured by using the composition for manufacturing the gasket for electromagnetic shielding.

The electromagnetic shielding gasket may have an electromagnetic shielding rate of 68 to 121 dB measured at a frequency of 30 MHz to 1.5 GHz according to ASTM D4935-99, and a thermal conductivity of 1.0 to 1.4 W/mK, measured according to ASTM E1461.

The composition for manufacturing an electromagnetic wave shielding gasket according to an embodiment of the present invention may provide an electromagnetic wave shielding gasket having excellent electromagnetic wave shielding effect and thermal conductivity.

1 is an SEM photograph of a dendritic conductive filler prepared in Preparation Example 1. FIG.
2 is an SEM photograph of a spherical conductive filler.
3 is an SEM photograph of a donut-shaped conductive filler.
4 is a graph showing a plane wave shielding effect of the electromagnetic wave shielding gasket prepared in Example 1. FIG.

Hereinafter, a composition for manufacturing an electromagnetic wave shielding gasket according to an embodiment of the present invention will be described in detail.

The composition for manufacturing an electromagnetic wave shielding gasket according to an embodiment of the present invention includes 100 parts by weight of a conductive filler, 1 to 15 parts by weight of a silane crosslinking agent, and 1 to 10 parts by weight of a solvent, but does not contain any silicone resins including thermosetting silicone resins. .

While the silane crosslinking agent is a monomer, all silicone resins including the thermosetting silicone resin are polysilicon, a kind of polymer.

When the content of each component is within the above range, it exhibits suitable resistance and electromagnetic shielding effect, and mechanical properties such as elongation can be secured, and when the content is outside the above range, insufficient resistance and mechanical properties or uncured phenomenon occurs. I can.

As described above, the composition for manufacturing the electromagnetic wave shielding gasket is any silicone resin (i.e., a silicone polymer or polysilicon) including a thermosetting silicone resin such as poly(diphenylsiloxane) to which an end group such as a hydrocarbon radical or a halogenated hydrocarbon radical is attached. Also does not include. If the composition for manufacturing the electromagnetic shielding gasket contains a silicone polymer, a gasket having excellent electromagnetic shielding rate and thermal conductivity cannot be manufactured (see Comparative Example 1).

The conductive filler may contain dendritic particles. For example, the conductive filler may be composed of dendritic particles. In the present specification, the "dendritic particle" refers to a particle having a large number of contact points with other particles when it is formed in a tree branch shape and exists in a powder state with other particles. When the conductive filler includes dendritic particles, the surface area of the conductive filler is widened compared to the case of including particles of other shapes such as spherical particles or doughnut-shaped particles, thereby providing electromagnetic wave shielding and heat dissipation effects in the electromagnetic wave shielding gasket. Can be improved.

The conductive filler may include silver, copper, nickel, copper coated with silver, nickel coated with silver, graphite coated with silver, glass coated with silver, or a combination thereof.

For example, the conductive filler is copper coated with silver, and the ratio of the silver and the copper may be 10 to 25 parts by weight to 50 to 60 parts by weight.

The conductive filler may have an average particle size of 0.5 to 50 μm, for example, 10 to 40 μm. If the average particle size of the conductive filler is within the above range, the fine particles do not clump together and thus dispersibility is good, and the particle size is suitable so that it does not easily settle in the composition, so that separation may not occur.

The silane crosslinking agent may include ketoxime silane.

The ketoxime silane is tetrakis(methylethylketoxime)silane, methyltris(dimethylketoxime)silane, methyltris(methylethylketoxime)silane, ethyltris(methylethylketoxime)silane, methyltris(methylisobutyl) Ketoxime)silane, vinyl tris(methylethylketoxime)silane, bis(ethylmethylketoxime)methoxymethylsilane, or a combination thereof.

The composition for manufacturing the electromagnetic wave shielding gasket may further include a catalyst, a filler, a plasticizer, or a combination thereof.

Specifically, organic-Ti or Sn may be used as the catalyst, but is not limited thereto.

Specifically, as the filler, CaCO ₃ , fumed silica, TiO _2, etc. may be used, but is not limited thereto.

As the plasticizer, poly(dimethylsiloxane) (CH ₃ terminated PDMS), etc., specifically terminated with a methyl group may be used, but the present invention is not limited thereto.

The composition for manufacturing the electromagnetic wave shielding gasket may further include other additives in addition to the above-described components.

The solvent may include a hydrocarbon, a halogenated hydrocarbon, an ester, or a combination thereof.

The solvent may be a hydrocarbon solvent such as toluene, xylene, or cyclohexane; Halogenated hydrocarbon solvents such as chloroform and carbon tetrachloride; Ester solvents such as ethyl acetate and butyl acetate; Or a combination thereof.

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The composition for manufacturing a gasket for electromagnetic wave shielding has a first available touch curing time of 2 to 4 minutes, a complete drying time of 95% complete adhesion is 10 to 14 hours, and sealed storage at -10°C to 5°C 3 To 5 months.

In addition, the composition for manufacturing the electromagnetic shielding gasket may have a Shore hardness of 45 to 55 after curing.

Another aspect of the present invention provides a gasket for electromagnetic wave shielding prepared from the composition for manufacturing the gasket for electromagnetic wave shielding. Specifically, the electromagnetic wave shielding gasket may be prepared by applying the composition for producing the electromagnetic wave shielding gasket to an adherend and then completely curing it.

The curing may be performed by drying the composition for manufacturing the electromagnetic wave shielding gasket using hot air, infrared (IR) or near infrared (NIR) so as to be completely curable.

In addition, the electromagnetic shielding gasket may have an electromagnetic shielding rate of 68 to 121 dB, measured at a frequency of 30 MHz to 1.5 GHz according to ASTM D4935-99, and a thermal conductivity of 1.0 to 1.4 W/mK, measured according to ASTM E1461. .

Hereinafter, the present invention will be described with reference to the following examples, but the present invention is not limited to the following examples.

Preparation Example 1: Preparation of a dendritic conductive filler

300 g of copper powder having a diameter of 10 μm was put into 3 L of pure water and stirred at 400 rpm for 5 minutes with a stirrer. Then, 1 g of PEI (polyethylenimine) was added to the stirred copper powder, followed by stirring for 5 minutes. Here, 277.78g of potassium silver cyanide (KAgCN ₂ ) and 555.56g of sodium cyanide (NaCN) and 12g of 1,2,3-Benzotriazole as a stabilizer were mixed with 300ml of pure water. It reacted for 10 minutes. After plating was completed, it was washed and dried at 70° C. for 1 hour and 30 minutes after treatment with fatty acids. As a result, a resinous conductive filler coated with silver (Ag) on copper (Cu) particles was obtained.

Example 1: Preparation of a composition for manufacturing an electromagnetic shielding gasket and a gasket for electromagnetic shielding

(Preparation of composition for manufacturing gasket for electromagnetic wave shielding)

100 parts by weight of the resinous conductive filler prepared in Preparation Example 1, 1 part by weight of methyltris (methylethylketoxime) silane, 7 parts by weight of bis(ethylmethylketoxime)methoxymethylsilane, and 5 parts by weight of toluene by hand mixing for 10 minutes Thus, a uniform composition for manufacturing an electromagnetic shielding gasket was prepared.

(Manufacture of electromagnetic shielding gasket)

The prepared composition for manufacturing an electromagnetic wave shielding gasket was dispensed on a polycarbonate substrate cleaned with alcohol. When dispensing, dispensing by adjusting the discharge pressure so that the length of the gasket becomes 10cm and the width of 0.5mm by using a nozzle with an inner diameter of 0.5mm, cure for 15 hours at 25℃ and 40-50% of relative humidity. Formed.

Comparative Example 1: Preparation of a composition for manufacturing an electromagnetic wave shielding gasket and a gasket for electromagnetic wave shielding

(Preparation of composition for manufacturing gasket for electromagnetic wave shielding)

As the conductive filler, the dendritic conductive filler prepared in Preparation Example 1 was used, and instead of a silicone-based crosslinking agent such as methyltris (methylethylketoxime) silane and bis (ethylmethylketoxime)methoxymethylsilane, a room temperature moisture-curable one-component silicone A resin composition, Dow Corning's jailbreak type RTV DC 210 product was used. In addition, toluene was used as a solvent. First, 30% by weight of a room temperature moisture-curable silicone resin (that is, a product of DC 210, a jailbreak type RTV of Dow Corning) and 9.9% by weight of toluene were added, followed by pre-stirring by hand mixing for 3 minutes and uniformly mixed. Here, by adding 60% by weight of the dendritic conductive filler prepared in Preparation Example 1, a composition for preparing a uniform electromagnetic wave shielding gasket was prepared by hand mixing again.

(Manufacture of electromagnetic shielding gasket)

The prepared composition for manufacturing an electromagnetic wave shielding gasket was dispensed on a polycarbonate substrate cleaned with alcohol. When dispensing, dispensing by adjusting the discharge pressure so that the length of the gasket becomes 10cm and the width of 0.5mm by using a nozzle with an inner diameter of 0.5mm, cure for 4 hours at 25℃ and 40-50% of relative humidity. Formed.

Comparative Example 2: Preparation of a composition for manufacturing an electromagnetic shielding gasket and a gasket for electromagnetic shielding

In place of the dendritic conductive filler prepared in Preparation Example 1, a spherical, silver-coated copper (Ag-Cu) R13-18T was used, and electromagnetic wave shielding was performed in the same manner as in Example 1. A composition for manufacturing a gasket and a gasket for shielding electromagnetic waves were prepared.

Comparative Example 3: Preparation of a composition for manufacturing an electromagnetic shielding gasket and a gasket for electromagnetic shielding

In place of the dendritic conductive filler prepared in Preparation Example 1, a doughnut-shaped conductive filler coated with silver (Ag) on copper (Cu) particles manufactured by A company, a competitor, was used, and the same as in Example 1 By the method, a composition for manufacturing an electromagnetic wave shielding gasket and a gasket for electromagnetic wave shielding were prepared.

Evaluation Example 1: Evaluation of particle shape

Taking SEM (scanning electron microscope) pictures of the dendritic conductive filler prepared in Preparation Example 1, the spherical conductive filler used in Comparative Example 2, and the donut-shaped conductive filler used in Comparative Example 3 are taken, and FIGS. Each is shown in Figure 3.

Referring to FIG. 1, it can be seen that the conductive filler prepared in Preparation Example 1 is dendritic and has relatively very many contact points between particles.

Referring to FIG. 2, it can be seen that the conductive filler used in Comparative Examples 1 and 2 is spherical and has relatively very few contact points between particles.

Referring to FIG. 3, it can be seen that the conductive filler used in Comparative Example 3 has a donut shape and has relatively very few contact points between particles.

Evaluation Example 2: Evaluation of properties of a composition for manufacturing an electromagnetic shielding gasket and a gasket for electromagnetic shielding

The physical properties of the electromagnetic wave shielding gaskets prepared in Example 1 and Comparative Examples 1 to 3 were evaluated in the following manner, and the results are shown in Table 1 below.

Dispersion (gasket uniformity) evaluation

Using a 400-fold magnification microscope, the gasket surface and cross-section voids, the shape of the agglomerate, and the frequency of discovery were evaluated as 4 grades as follows.

-◎: Very good

-○: Good

-△: Not bad

-X: Bad

Electromagnetic shielding rate evaluation

According to ASTM D4935-99 method, Agilent's spectrum analyzer (Agilent CSA spectrum analyzer) and US Electro-Metrics' 2-port flanged coaxial holder (EM-2107) were used to measure 133.0 mm in diameter at a frequency ranging from 30 MHz to 1.5 GHz. The electromagnetic shielding rate for each gasket specimen was measured. The results are shown in Fig. 4 and Table 1. In FIG. 4, the vertical axis represents the electromagnetic wave absorption rate as a negative value, and when a negative value is read as a positive value by changing only a sign, the positive value indicates the electromagnetic wave shielding rate.

Thermal conductivity evaluation

Specimens were prepared with a thickness of 0.8790 mm from each of the gaskets, and the thermal conductivity of each specimen was measured according to the ASTM E1461 method.

Dispersibility Electromagnetic shielding rate
(dB) Thermal conductivity
(W/mK) Example 1 ◎ 68~121 1.2 Comparative Example 1 ◎ 60~80 0.5 Comparative Example 2 ◎ 15-20 0.3 Comparative Example 3 ◎ 40-50 0.4

Referring to Table 1, it was found that the electromagnetic wave shielding gasket prepared in Example 1 has superior electromagnetic wave shielding rate and thermal conductivity compared to the electromagnetic wave shielding gasket prepared in Comparative Examples 1 to 3.

In the above, preferred embodiments of the present invention have been described with reference to the drawings and embodiments, but this is only exemplary, and various modifications and other equivalent embodiments are possible from those of ordinary skill in the art. You will be able to understand. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims (9)

100 parts by weight of a conductive filler, 1 to 15 parts by weight of a silane-based crosslinking agent, and 1 to 10 parts by weight of a solvent, but does not contain any silicone resins including thermosetting silicone resins,
The solvent is a composition for manufacturing a gasket for electromagnetic shielding comprising a hydrocarbon, a halogenated hydrocarbon, an ester, or a combination thereof. The method of claim 1,
The conductive filler is a composition for manufacturing a gasket for shielding electromagnetic waves containing dendritic particles. The method of claim 1,
The conductive filler is an electromagnetic wave shielding comprising silver, copper, nickel, copper coated with silver, nickel coated with silver, graphite coated with silver, glass coated with silver, or a combination thereof having an average particle diameter of 0.5-50㎛ Composition for manufacturing a gasket. The method of claim 3,
The conductive filler is copper coated with silver, and the ratio of the silver and the copper is 10 to 25 parts by weight to 50 to 60 parts by weight of an electromagnetic wave shielding gasket manufacturing composition. The method of claim 1,
The silane-based crosslinking agent composition for manufacturing an electromagnetic wave shielding gasket comprising ketoxime silane. The method of claim 5,
The ketoxime silane is tetrakis(methylethylketoxime)silane, methyltris(dimethylketoxime)silane, methyltris(methylethylketoxime)silane, ethyltris(methylethylketoxime)silane, methyltris(methylisobutyl) Ketoxin) silane, vinyl tris (methyl ethyl ketoxime) silane, bis (ethyl methyl ketoxime) methoxymethyl silane, or a composition for manufacturing an electromagnetic wave shielding gasket comprising a combination thereof. delete An electromagnetic wave shielding gasket manufactured using the composition for manufacturing an electromagnetic wave shielding gasket according to any one of claims 1 to 6. The method of claim 8,
The electromagnetic shielding gasket has an electromagnetic shielding rate of 68 to 121 dB measured at a frequency of 30 MHz to 1.5 GHz according to ASTM D4935-99, and a thermal conductivity of 1.0 to 1.4 W/mK measured according to ASTM E1461. .

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