KR20200009863A - Composition for preparing electromagnetic wave shielding gasket and electromagnetic wave shielding gasket prepared therefrom - Google Patents

Abstract

The present invention relates to a composition for manufacturing a gasket for shielding electromagnetic waves and to a gasket for shielding electromagnetic waves. The composition for manufacturing a gasket for shielding electromagnetic waves comprises: 100 parts by weight of a conductive filler; 1 to 15 parts by weight of a silane-based cross-linking agent; and 1 to 10 parts by weight of a solvent, and does not include any silicone resins as well as thermosetting silicone resins.

Description

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

 Disclosed are a composition for producing a gasket for electromagnetic shielding and a gasket for electromagnetic shielding. More specifically, a composition for producing an electromagnetic wave shielding gasket including a silane-based crosslinking agent but not containing any silicone resin, including a thermosetting silicone resin, and an electromagnetic wave shielding gasket prepared from the composition for preparing an electromagnetic wave shielding gasket.

Harmful electromagnetic waves generated from circuits installed inside various electrical, electronic and communication equipment may cause malfunction or radio interference of the equipment, resulting in deterioration of product performance and shortening of product life. Furthermore, electromagnetic waves cause problems such as increasing the temperature of biological tissue cells by thermal action when they penetrate the human body, thereby weakening immune function. On the other hand, with the development of electronic circuit integration technology, it has become possible to use unit circuits having various functions in a narrow space. However, electromagnetic interference (EMI) generated from each circuit is an important problem between adjacent circuits. Increasingly, there is an increasing demand for products that comply with electromagnetic compatibility (EMC).

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

Conventional electromagnetic wave absorbers are materials that attenuate propagation energy or reduce reflected waves below a reference value by using high frequency loss characteristics of constituent materials, and are classified into conductive loss materials, dielectric loss materials, and magnetic loss materials, depending on the materials used. The composite ferrite electromagnetic wave absorber mainly used as an electromagnetic wave absorber is a mixture of ferrite magnetic material such as silicone rubber and plastic as a support material, which is manufactured in the form of a sheet of about 1 mm and used for anti-radar antireflection in the GHz band. .

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

In addition, the conventional electromagnetic shielding and absorption sheet is coated with a soft magnetic metal powder (for example, permalloy, senddust, Fe-Si, Ni-Fe, etc.) on one side or both sides of the conductive layer. The electromagnetic shielding and absorption layers are laminated, and the electromagnetic shielding and absorption characteristics are good, but there is a limit to efficiently dissipating heat generated from the sheet itself.

On the other hand, Korean Laid-Open Patent Publication No. 2004-0033257 discloses "One or more electromagnetic wave absorbing layers in which soft magnetic metal powder is dispersed in a base polymer, and one or more electrical insulating layers in which an electrically insulating thermal conductive polymer is dispersed in a base polymer. Is an electromagnetic wave absorptive thermal conductive sheet having a dielectric breakdown voltage of 1 KV or more in the thickness direction of the sheet ”, but the electromagnetic wave absorptive thermal conductive sheet has electromagnetic shielding and heat dissipation characteristics. Insufficient In addition, Japanese Laid-Open Patent Publication No. 2002-076683 discloses an "electromagnetic wave absorptive heat dissipation sheet composed of a laminate in which an electromagnetic wave absorbing layer and a heat dissipation layer are laminated". Do.

One embodiment of the present invention provides a composition for preparing an electromagnetic shielding gasket including a silane-based crosslinking agent, but does not include any silicone resin, including a thermosetting silicone resin.

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

One aspect of the invention,

Provided is a composition for preparing a gasket for electromagnetic wave shielding, 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, and not including any silicone resin, including a thermosetting silicone resin.

The conductive filler may include dendritic particles.

The conductive filler may include silver having a mean particle size 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 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 a ketoxime silane.

The ketoxime silane is tetrakis (methylethylketoxime) silane, methyltris (dimethylketoxime) silane, methyltris (methylethylketoxime) silane, ethyltris (methylethylketoxime) silane, methyltris (methyl isobutyl Ketoxime) silane, vinyl tris (methylethylketoxime) silane, bis (ethylmethylketoxime) methoxymethylsilane or combinations thereof.

The solvent may comprise silicone oil, hydrocarbons, halogenated hydrocarbons, esters, siloxanes or combinations thereof.

Another aspect of the invention,

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

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 by ASTM D4935-99, and a thermal conductivity of 1.0 to 1.4 W / mK measured by ASTM E1461.

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

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

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

Composition for producing a gasket for electromagnetic wave shield 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 crosslinker and 1 to 10 parts by weight of a solvent, but does not include any silicone resin, including a thermosetting silicone resin. .

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

When the content of each component is in the above range, it exhibits a suitable resistance and electromagnetic shielding effect, and secures mechanical properties such as elongation, and when the content is outside the above range, shortage of resistance and mechanical properties or uncured phenomenon may occur. Can be.

As described above, the composition for preparing the electromagnetic wave shielding gasket is any silicone resin (ie, silicone polymer or polysilicon), including a thermosetting silicone resin such as poly (diphenylsiloxane) to which end groups such as hydrocarbon radicals or halogenated hydrocarbon radicals are attached. Does not include If the composition for preparing the electromagnetic wave shielding gasket includes a silicone polymer, a gasket having excellent electromagnetic shielding rate and thermal conductivity may not be manufactured (see Comparative Example 1).

The conductive filler may include dendritic particles. For example, the conductive filler may be composed of dendritic particles. As used herein, the term "resin particle" refers to a particle having a contact shape with other particles when formed in a branch shape and present in a powder state together with other particles. When the conductive filler includes dendritic particles, the surface area of the conductive filler is wider than that of other particles such as spherical particles or donut-shaped particles, thereby providing electromagnetic shielding and heat radiation effects in the electromagnetic 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. When the average particle size of the conductive filler is within the above range, the fine particles do not agglomerate with each other and have good dispersibility, and the size of the particles may not be easily settled in the composition so that no separation phenomenon may occur.

The silane crosslinker may comprise a ketoxime silane.

The ketoxime silane is tetrakis (methylethylketoxime) silane, methyltris (dimethylketoxime) silane, methyltris (methylethylketoxime) silane, ethyltris (methylethylketoxime) silane, methyltris (methyl isobutyl Ketoxime) silane, vinyl tris (methylethylketoxime) silane, bis (ethylmethylketoxime) methoxymethylsilane or combinations thereof.

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

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

Specifically, the filler may be CaCO ₃ , fumed silica, TiO _2, or the like, but is not limited thereto.

Specifically, the plasticizer may be poly (dimethylsiloxane) terminated with methyl group (CH ₃ terminated PDMS) and the like, but is not limited thereto.

The composition for preparing the electromagnetic shielding gasket may further include other additives in addition to the above components.

The solvent may comprise silicone oil, hydrocarbons, halogenated hydrocarbons, esters, siloxanes or combinations thereof.

The solvent may be a hydrocarbon solvent such as toluene, xylene, cyclohexane, or the like; Halogenated hydrocarbon solvents such as chloroform and carbon tetrachloride; Ester solvents such as ethyl acetate and butyl acetate; Long-chain siloxane solvents such as hexanemethyldisiloxane, octamethyltrisiloxane, and decamethyltetrasiloxane; Cyclic siloxane solvents such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, heptamethylphenylcyclotetrasiloxane, heptamethylvinylcyclotetrasiloxane and decamethylcyclopentasiloxane; Or combinations thereof.

Liquid silicone oil may be used as the solvent. It is preferable that the viscosity is 3.7 to 4.5 cps (centipoise), and it contains an organic group selected from the group consisting of chloropropyl group, phenylethyl group, C6-C20 alkyl group, trichloropropyl group, epoxy group and cyano group. It is preferred to be volatile. Liquid silicone oil has a molecular structure in which silicon, in which organic groups are bonded, is connected by siloxane bonds (Si-O-Si). Not only excellent insulation, but also serves as a binder (binder). In addition, the liquid silicone oil has a small surface tension and has antifoaming properties.

The composition for preparing the electromagnetic wave shielding gasket has a time of 2 minutes to 4 minutes for the first use, and a complete drying time of 10 hours to 14 hours for 95% complete adhesion, and a closed storage at -10 ° C to 5 ° C. Can be stored for up to 5 months.

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

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

The curing may be performed by drying the composition for preparing the electromagnetic shielding gasket for the complete curing using hot air, infrared (IR) or near infrared (NIR).

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

Hereinafter, although an Example is given and described this invention, this invention is not limited only to a following example.

Production Example 1: Preparation of Dendritic Conductive Filler

300 g of copper powder having a diameter of 10 µm was put in 3 L of pure water, and stirred at 400 rpm for 5 minutes with a stirrer. Thereafter, 1 g of PEI (polyethylenimine) was added to the stirred copper powder, followed by stirring for 5 minutes. 277.78 g of Potsssium Silver Cyanide (KAgCN ₂ ) and 555.56 g of Sodium cyanide (NaCN) and 12 g of 1,2,3-Benzotriazole stabilizer were mixed in 300 ml of pure water, and then The reaction was carried out for 10 minutes. After the plating was finished, washed and treated with fatty acid and dried at 70 ℃ for 1 hour 30 minutes. As a result, a resinous conductive filler obtained by coating silver (Ag) on copper (Cu) particles was obtained.

Example 1 Preparation of Electromagnetic Shielding Gasket Composition and Electromagnetic Shielding Gasket

(Production of Composition for Manufacturing Gasket for Electromagnetic Shielding)

100 parts by weight of the dendritic 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 are hand mixed. To prepare a composition for producing a uniform electromagnetic shielding gasket.

 (Production of electromagnetic shielding gasket)

The prepared composition for shielding electromagnetic wave gasket was dispensed on a polycarbonate substrate cleanly washed with alcohol. When dispensing, use a nozzle with a 0.5mm inner diameter to dispense the gasket to adjust the discharge pressure so that the length of the gasket is 10cm and width 0.5mm, and then harden for 15 hours at 25 ° C and 40-50% relative humidity. Formed.

Comparative Example 1: Preparation of electromagnetic shielding gasket composition and electromagnetic shielding gasket

(Production of Composition for Manufacturing Gasket for Electromagnetic Shielding)

As the conductive filler, the dendritic conductive filler prepared in Preparation Example 1 was used, and at room temperature moisture curable one-component silicone instead of silicone-based crosslinking agents such as methyltris (methylethylketoxime) silane and bis (ethylmethylketoxime) methoxymethylsilane. DC 210, a jailbreak-type RTV from Dow Corning Co., Ltd., a resin composition was used. In addition, toluene was used as the solvent. First, 30 wt% of room temperature moisture-curable silicone resin (ie, DC 210 manufactured by Dow Corning RTV) and 9.9 wt% of toluene were added thereto, followed by preliminary stirring by hand mixing for 3 minutes to uniformly mix. 60 wt% of the dendritic conductive filler prepared in Preparation Example 1 was added thereto, thereby preparing a composition for preparing a uniform electromagnetic wave shielding gasket by hand mixing.

(Production of electromagnetic shielding gasket)

The prepared composition for shielding electromagnetic wave gasket was dispensed on a polycarbonate substrate cleanly washed with alcohol. When dispensing, use a nozzle of 0.5mm inner diameter to dispense the gasket to adjust the discharge pressure to make the gasket 10cm long and 0.5mm wide, and then harden for 4 hours at 25 ° C and 40-50% relative humidity. Formed.

Comparative Example 2: Preparation of Electromagnetic Shielding Gasket Composition and Electromagnetic Shielding Gasket

Instead of the dendritic conductive filler prepared in Preparation Example 1 was prepared using a spherical, R13-18T of Ferro Co., which is copper (Ag-Cu) coated with silver, and for shielding electromagnetic waves in the same manner as in Example 1 A gasket composition and an electromagnetic shielding gasket were prepared.

Comparative Example 3: Preparation of electromagnetic shielding gasket composition and electromagnetic shielding gasket

In place of the dendritic conductive filler prepared in Preparation Example 1 was prepared using a donut-shaped conductive filler coated with silver (Ag) to the copper (Cu) particles produced by a competitor A, the same as in Example 1 By the method, a composition for preparing an electromagnetic shielding gasket and an electromagnetic shielding gasket were prepared.

Evaluation Example 1 Shape Evaluation of Particles

Scanning electron microscope (SEM) photographs 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 were taken to illustrate a scanning electron microscope (SEM) photograph. 3 is shown respectively.

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

Referring to FIG. 2, it can be seen that the conductive fillers used in Comparative Examples 1 and 2 are spherical and thus have relatively few contact points between the particles.

Referring to FIG. 3, it can be seen that the conductive filler used in Comparative Example 3 is a toroidal type, having relatively few contact points between the particles.

Evaluation Example 2: Evaluation of Properties of Electromagnetic Shielding Gasket Composition and Electromagnetic Shielding Gasket

The physical properties of the electromagnetic shielding gasket manufactured in Example 1 and Comparative Examples 1 to 3 were evaluated by the following method, and the results are shown in Table 1 below.

Dispersibility (Gasket Uniformity) Assessment

The gasket surface and the cross section formed by using a 400 times magnification microscope, the void (void), aggregated particles (agglomerate) and the frequency of the evaluation was evaluated as four grades as follows.

-◎: Very good

-○: good

△: not bad

-X: bad

Electromagnetic Shielding Rate Evaluation

133.0 mm in diameter at frequencies ranging from 30 MHz to 1.5 GHz using the American Agilent Spectrum Analyzer (Agilent CSA Spectrum Analyzer) and US Electro-Metrics 2-port flanged coaxial holder (EM-2107) according to ASTM D4935-99 The electromagnetic shielding rate for each of the gasket specimens was measured. The results are shown in Figure 4 and Table 1. In FIG. 4, the vertical axis represents the electromagnetic wave absorptivity as a negative value, and when the negative value is read as a positive value by changing only the sign, the positive value represents the electromagnetic shielding rate.

Thermal conductivity evaluation

Specimens were prepared to a thickness of 0.8790 mm from the respective 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, the electromagnetic shielding gasket manufactured in Example 1 was found to be superior to both the electromagnetic shielding rate and thermal conductivity compared to the electromagnetic shielding gasket prepared in Comparative Examples 1 to 3.

Although the preferred embodiments according to the present invention have been described above with reference to the drawings and the embodiments, these are merely exemplary, and various modifications and equivalent other embodiments are possible to those skilled in the art. You will understand. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims (9)

A composition for producing 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, and containing no silicone resin, including a thermosetting silicone resin. The method of claim 1,
The conductive filler is a composition for producing a gasket for electromagnetic wave shield containing dendritic particles. The method of claim 1,
The conductive filler is electromagnetic shielding including 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 to 50 µm. Composition for preparing a gasket for use. The method of claim 3,
The conductive filler is a copper coated with silver, the ratio of the silver and the copper is 10 to 25 parts by weight to 50 to 60 parts by weight of the composition for producing a gasket for electromagnetic shielding. The method of claim 1,
The silane-based crosslinking agent is a composition for manufacturing a gasket for electromagnetic shielding containing ketoxime silane. The method of claim 5,
The ketoxime silane is tetrakis (methylethylketoxime) silane, methyltris (dimethylketoxime) silane, methyltris (methylethylketoxime) silane, ethyltris (methylethylketoxime) silane, methyltris (methyl isobutyl Ketoxime) Silane, vinyl tris (methyl ethyl ketoxime) silane, bis (ethyl methyl ketoxime) methoxymethyl silane or a combination thereof. The method of claim 1,
The solvent is a composition for producing a gasket for electromagnetic shielding comprising a silicone oil, a hydrocarbon, a halogenated hydrocarbon, ester, siloxane or a combination thereof. An electromagnetic shielding gasket manufactured using the composition for producing an electromagnetic shielding gasket according to any one of claims 1 to 7. The method of claim 8,
The electromagnetic shielding gasket has an electromagnetic shielding ratio of 68 to 121 dB measured at a frequency of 30 MHz to 1.5 GHz by ASTM D4935-99, and an electromagnetic shielding gasket having a thermal conductivity of 1.0 to 1.4 W / mK measured by ASTM E1461. .

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