KR101937650B1 - An electromagnetic wave shielding sheet comprising a heat peelable adhesive layer - Google Patents

Abstract

The present invention relates to an adhesive layer obtained by ultraviolet curing a pressure-sensitive adhesive composition comprising a (meth) acrylic polymer prepolymer, heat-expandable microspheres, conductive particles, additives, and photoinitiators; A release layer formed on one surface of the adhesive layer; And an electromagnetic wave shielding layer formed on the other surface of the adhesive layer, wherein the adhesive layer and the adherend are peelable from each other by heating.
The electromagnetic wave shielding sheet of the present invention is advantageous in that the electromagnetic wave shielding sheet of the present invention has excellent electromagnetic wave shielding effect and adhesive force and can be easily peeled off at an arbitrary timing and can prevent or prevent contamination of the adherend upon peeling .

Description

An electromagnetic wave shielding sheet comprising a heat peelable conductive adhesive layer (a heat peelable adhesive layer)

The present invention relates to a pressure-sensitive adhesive composition for electronic parts and an electromagnetic wave shielding sheet using the same, and more particularly, to a pressure-sensitive adhesive composition for electronic parts which is excellent in electromagnetic wave shielding function and adhesive property, And to an electromagnetic wave shielding sheet using the composition.

Most electronic products, including displays, are made up of a number of different combinations of materials. To assemble such electronic products, a variety of thickness and performance adhesives have been used to facilitate the functioning of these materials. The pressure sensitive adhesive applied to electronic products may require not only the function of bonding different materials but also the function of electromagnetic wave absorbing property or electromagnetic wave shielding property so that the bonding materials can exert their proper function.

Electromagnetic interference caused by mutual unwanted electromagnetic waves between electric and electronic devices has become serious, and recently, there is concern about damage to the human body. There are two methods of electromagnetic wave shielding and electromagnetic wave absorption as a method for reducing such unwanted electromagnetic waves, that is, electromagnetic noise.

The shielding and absorption of electromagnetic waves means that a protection material made of a metal plate or a fibrous conductive material is placed between an electromagnetic wave generating region and two surrounding electronic regions to prevent electrons belonging to one side from affecting the other.

The permeability, which indicates the ability of EMI absorption, is a constant that quantifies how easily the magnetic flux (in the magnetic force lines) passes. When a material with a high magnetic permeability and a material with a low magnetic permeability are simultaneously present in a magnetic field in which a magnetic field is present, the magnetic field lines converge to a material having a high permeability. When a magnetic field is transmitted through a magnetic material, . In other words, magnetic flux density means the number of magnetic flux lines that permeate per unit area. Therefore, the magnetic flux density is higher than the applied magnetic flux lines, and the lower magnetic flux density is expressed as a constant of permeability.

Korean Patent Laid-Open Publication No. 2009-01141634 relates to an ultra-thin conductive tape for shielding electromagnetic waves and a method of manufacturing the same, and relates to a method of manufacturing the ultra-thin conductive tape for electromagnetic wave shielding, An ultra-thin insulating film base layer having a hole punctured at regular intervals, wherein the conductive base material coated with a conductive adhesive agent on one side or both sides thereof is plated with a metal having excellent electrical conductivity; At least one plating layer surrounding the ultra thin insulating film base layer with a perforated hole as a boundary and plated with a metal having excellent electric conductivity by electrolytic, electroless, substitution, vacuum deposition or sputtering; An electromagnetic interference shielding material characterized by comprising a conductive pressure- Quot; ultra thin film conductive tape for use ". However, although the above-mentioned technique has an action effect showing the electromagnetic wave shielding effect, its manufacturing process is complicated and there is a limit in the adhesive force.

Korean Patent Laid-Open Publication No. 2004-0085079 discloses a heat-peelable double-faced pressure-sensitive adhesive sheet comprising a heat-peelable pressure-sensitive adhesive layer containing thermally expandable microspheres, but does not mention a technical structure for imparting an electromagnetic wave shielding function.

Therefore, it is urgently required to develop an electromagnetic wave shielding sheet having an excellent electromagnetic wave shielding function, which is excellent in adhesiveness and releasability in a heat-peelable pressure-sensitive adhesive sheet.

Korea Patent Publication No. 2004-0085079 Korean public patent 2009-01141634

An object of the present invention is to provide an electromagnetic wave shielding sheet excellent in heat releasability while solving the above conventional problems.

It is another object of the present invention to provide a bonding composition for electronic parts and an electromagnetic wave shielding sheet using the composition, which have remarkably excellent electromagnetic shielding ratio, surface resistance, vertical resistance, adhesive strength, thickness variation, surface smoothness and the like.

The present invention relates to an adhesive layer obtained by ultraviolet curing a pressure-sensitive adhesive composition comprising a (meth) acrylic polymer prepolymer, heat-expandable microspheres, conductive particles, additives, and photoinitiators; A release layer formed on one surface of the adhesive layer; And an electromagnetic wave shielding layer formed on the other surface of the adhesive layer, wherein the adhesive layer and the adherend are peelable from each other by heating.

According to a preferred embodiment of the present invention, the heat peelable pressure-sensitive adhesive composition comprises 70 to 99 parts by weight of a (meth) acrylic acid ester monomer having an alkyl group having 1 to 20 carbon atoms, a polar monomer 1 to 30 15 to 75 parts by weight of heat expandable microparticles, 3 to 10 parts by weight of conductive particles, 1 to 10 parts by weight of an additive and 0.01 to 10 parts by weight of a photoinitiator are added to 100 parts by weight of a resin syrup prepared by partially polymerizing a monomer .

According to another preferred embodiment of the present invention, the electromagnetic wave shielding layer is an electromagnetic wave shielding fiber produced by an electroless plating method.

In order to solve the above-mentioned problems, the present invention also provides a method for producing a photopolymerizable composition, which comprises irradiating a monomer containing a (meth) acrylic acid ester monomer having an alkyl group of 1 to 20 carbon atoms, a polar monomer copolymerizable with the monomer, and a photoinitiator under a nitrogen atmosphere Preparing a prepolymer in a syrup state; Adding thermally expandable microspheres, additives, conductive particles, and a photoinitiator to the syrup, followed by stirring to prepare a pressure-sensitive adhesive composition; Applying the agitated pressure-sensitive adhesive composition on one side of the release film to form a pressure-sensitive adhesive layer; Shielding the electromagnetic wave shielding fibers on the adhesive layer; And curing the adhesive resin composition while passing the UV-zone through the UV-zone. The present invention also provides a method of manufacturing a heat dissipating electromagnetic wave shielding sheet.

According to a preferred embodiment of the present invention, the Yubi zone has 3 to 7 steps, and the UV-light source is arranged in the order of LED-Bulb-LED.

According to another preferred embodiment of the present invention, the output amount of the LED is 7,000 to 9,000 W, and the output amount of the bulb is 50 to 200 W.

The electromagnetic wave shielding sheet of the present invention is excellent in electromagnetic wave shielding effect and adhesive force.

Further, the electromagnetic wave shielding sheet of the present invention can be easily peeled off at an arbitrary timing, and there is an advantage that contamination of the adherend can be suppressed or prevented in peeling.

Hereinafter, the present invention will be described in detail with reference to embodiments and drawings of the present invention. It will be apparent to those skilled in the art that these embodiments are provided by way of illustration only for the purpose of more particularly illustrating the present invention and that the scope of the present invention is not limited by these embodiments .

The heat-peelable electromagnetic wave shielding sheet of the present invention comprises an adhesive layer obtained by ultraviolet curing a pressure-sensitive adhesive composition comprising a (meth) acrylic polymer prepolymer, a thermally expandable microsphere, conductive particles, an additive, and a photoinitiator; A release layer formed on one surface of the adhesive layer; And an electromagnetic wave shielding layer formed on the other surface of the adhesive layer, wherein the adhesive layer and the adherend are peelable from each other by heating.

The adhesive composition comprises 70 to 99 parts by weight of a (meta) acrylic acid ester monomer having an alkyl group having 1 to 20 carbon atoms and 1 to 30 parts by weight of a polar monomer copolymerizable with the monomer, and a resin syrup 15 to 75 parts by weight of heat expandable microspheres, 3 to 10 parts by weight of conductive particles, 1 to 10 parts by weight of an additive, and 0.01 to 10 parts by weight of a photoinitiator.

The pressure-sensitive adhesive composition of the present invention can be produced by a conventional method for producing a pressure-sensitive adhesive.

The adhesive resin forming the pressure-sensitive adhesive is generally formed by polymerization of monomers. Specifically, the monomer for forming the adhesive polymer resin may be mixed with a photoinitiator and an additive, and if necessary, a filler may be added and polymerized and coated on a release film to cure the adhesive or adhesive tape. It goes without saying that a polymerization initiator and a crosslinking agent may be added during the production of the adhesive composition. Preferably, in order to uniformly disperse the filler and other additives in the adhesive composition, the monomer for forming the adhesive polymer resin is first prepolymerized into a syrup state, and then the filler and other additives And the mixture is homogeneously stirred and then polymerized.

The kind of the (meth) acrylic acid ester monomer used in the present invention is not particularly limited, and for example, alkyl (meth) acrylate can be used. Examples of such a sugar compound include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, (Meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, 2- ethylhexyl , Isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate or tetradecyl (meth) acrylate.

Examples of the polar monomer copolymerizable with the monomer include, but are not limited to, a hydroxy group-containing monomer and a carboxyl group-containing monomer. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (Meth) acrylate, 2-hydroxyethyleneglycol (meth) acrylate or 2-hydroxypropyleneglycol (meth) acrylate. Examples of the carboxyl group-containing monomer include (meth) acrylic acid, 2- (meth) acryloyloxyacetic acid, 3- (meth) acryloyloxypropionic acid, 4- (meth) acryloyloxybutyric acid, Citric acid, maleic acid or maleic anhydride.

The adhesive composition of the present invention is characterized by comprising a photoinitiator together with the monomer as described above. Such a photoinitiator reacts by irradiation of ultraviolet rays or the like in the process of manufacturing an adhesive tape to initiate the curing reaction of the pressure-sensitive adhesive composition.

The type of photoinitiator that can be used in the present invention is not particularly limited, and examples thereof include? -Hydroxyketone compounds, phenylglyoxylate compounds, benzyldimethylketal compounds,? -Aminoketone compounds, and the like , But is not limited thereto. The weight ratio of the photoinitiator may be 0.01 to 10, preferably 0.01 to 5. By controlling the weight ratio of the initiator to the above range, excellent physical properties and productivity can be secured.

The additive may be one or more selected from the group consisting of boric acid, epoxy-based silane, and dispersant-providing agent. The content of the additive is preferably 1 to 10 parts by weight. When the amount is less than 1 part by weight, it is difficult to attain the purpose of adding the additive, and when it exceeds 10 parts by weight, adhesiveness may be deteriorated.

The conductive particles consist of at least one selected from the group consisting of copper, nickel, gold, silver, aluminum, graphite, graphene and boron nitride. The conductive particles may be composed of copper and nickel, and the ratio of copper to nickel is most preferably 2: 1, and the ratio of copper to nickel may be changed according to required physical properties.

The nickel is composed of a spike type nickel powder and a chain type nickel powder, and the spike type nickel powder and the chain type nickel powder are most preferably in a ratio of 1: 1, The ratio can be changed according to the conductivity.

It is preferable that the conductive particles have a particle size of 2 to 4 micrometers. If the particle size of the conductive particles is less than 2 micrometers, the conductive particles easily scatter and degrade the workability. When the conductive particles exceed 4 micrometers, It is impossible to form an adhesive layer showing uniform physical properties.

When the content of the conductive particles is less than 3 parts by weight, the heat resistance of the inorganic reheat adhesive and the conductivity of the conductive tape deteriorate. When the content of the conductive particles is more than 10 parts by weight, do.

The thermally expandable micropores are micropores that can be expanded or foamed by heating. The heat-peelable pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer containing the heat-expandable microspheres has a sufficient adhesive force when the adhesive force is required because unevenness is generated on the adhesive surface by heating to decrease the adhesive force, The peeling property is excellent. As described above, in the present invention, even when exposed to an acidic or alkaline chemical liquid, the thermally expandable microspheres are less likely to be altered, and the above functions as thermally expandable microspheres can be sufficiently expressed.

The content of the thermally expandable microspheres can be appropriately set in accordance with the lowering of the desired adhesive force and the like. The content of the thermally expandable microspheres is preferably 15 to 75 parts by weight based on 100 parts by weight of the (meth) acrylic partial polymer in the acrylic pressure-sensitive adhesive. When the content of the thermally expandable microspheres is less than 15 parts by weight, it is not preferable from the viewpoint of heat releasability, and when it exceeds 75 parts by weight, it is not preferable from the viewpoint of adhesiveness.

As the thermally expandable microspheres, any suitable thermally expandable microspheres can be used. As the thermally expandable microspheres, microspheres containing a substance which is easily swollen by heating, for example, in a shell having elasticity can be used. Such thermally expandable microspheres can be produced by any appropriate method, for example, a coacervation method, an interfacial polymerization method, or the like.

Examples of the substance that can be easily expanded by heating include a halogen such as propane, propylene, butene, normal butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, heptane, Low-boiling liquids such as cargo, tetraalkylsilane and the like; And azodicarbonamide which is gasified by pyrolysis.

Examples of the material constituting the shell include nitrile monomers such as acrylonitrile, methacrylonitrile,? -Chlor acrylonitrile,? -Ethoxyacrylonitrile, and fumaronitrile; Carboxylic acid monomers such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid and citraconic acid; Vinylidene chloride; Vinyl acetate; (Meth) acrylate, isobornyl (meth) acrylate, isobornyl (meth) acrylate, isobutyl (meth) acrylate, (Meth) acrylic acid esters such as hexyl (meth) acrylate, benzyl (meth) acrylate and? -Carboxyethyl acrylate; Styrene monomers such as styrene,? -Methyl styrene and chlorostyrene; Amide monomers such as acrylamide, substituted acrylamide, methacrylamide, and substituted methacrylamide, and the like. The polymer composed of these monomers may be either a homopolymer or a copolymer. Examples of the copolymer include vinylidene chloride-methyl methacrylate-acrylonitrile copolymer, methyl methacrylate-acrylonitrile-methacrylonitrile copolymer, methyl methacrylate-acrylonitrile copolymer, Acrylonitrile-methacrylonitrile-itaconic acid copolymer, and the like.

As the thermally expandable microspheres, an inorganic foaming agent or an organic foaming agent may be used. Examples of the inorganic foaming agent include ammonium carbonate, ammonium hydrogencarbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, and various azides. Examples of the organic foaming agent include chlorobenzene-based compounds such as trichloromonofluoromethane and dichloromonofluoromethane; Azo compounds such as azobisisobutyronitrile, azodicarbonamide, and barium azodicarboxylate; Hydrazine compounds such as para-toluenesulfonyl hydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, 4,4'-oxybis (benzenesulfonylhydrazide) and allyl bis (sulfonylhydrazide); a semicarbazide-based compound such as p-toluenesulfonyl semicarbazide, 4,4'-oxybis (benzenesulfonyl semicarbazide); Triazole-based compounds such as 5-morpholyl-1,2,3,4-thiatriazole; N-nitroso compounds such as N, N'-dinitrosopentamethylenetetramine and N, N'-dimethyl-N, N'-dinitrosoterephthalamide.

The particle diameter of the heat-expandable microspheres before heating is preferably 0.1 to 100 탆, more preferably 2 to 50 탆, still more preferably 5 to 30 탆, particularly preferably 10 to 20 탆, 15 mu m. Therefore, the particle size of the heat-expandable microspheres prior to heating is preferably 3 占 퐉 to 50 占 퐉, and more preferably 10 占 퐉 to 40 占 퐉, in terms of the average particle diameter. The particle diameter and the average particle diameter are values obtained by the particle size distribution measurement method in the laser scattering method.

The thermally expandable microspheres preferably have a suitable strength not ruptured until the volume expansion rate is preferably 5 times or more, more preferably 7 times or more, and even more preferably 10 times or more. When such thermally expandable microspheres are used, the adhesive force can be effectively lowered by the heat treatment.

The thickness of the adhesive layer constituting the electromagnetic wave shielding sheet of the present invention is preferably 5 to 500 micrometers, and if the thickness of the adhesive layer is less than 5 micrometers, the stress relaxation effect is insufficient at high temperature, If it is exceeded, it is not economical.

According to a preferred embodiment of the present invention, the electromagnetic wave shielding layer is formed of an electromagnetic wave shielding fiber material manufactured by an electroless plating method.

Generally, a method of imparting electromagnetic wave shielding performance to a polymer material that is an electrical non-conductor can be divided into two methods. First, a conductive filler is mixed with a polymer matrix resin. In the second method, aluminum, cobalt , Gold, copper, nickel, zinc, iron or graphite.

There are various methods of applying the electroconductive particles and the thin film. However, the electroconductive particles and the thin film are known to be applicable to textile products by a conductive particle coating method, a vacuum evaporation method, a method of knitting with metal fibers, and an electroless plating method. Among them, the electroless plating method is applicable to a substrate having a nonuniform surface structure such as fibers, and is known to have excellent durability and shielding effect.

Electroless plating is a method of depositing a metal film on a desired substrate by a chemical reaction by a self-catalyst in a solution in which a metal salt and a reducing agent coexist. Electroless plating is less economical than electroplating, , It is possible to form a metal film on the surface of glass, ceramics, plastic or fiber, which is an insulator, by adding catalyst activated nuclei to the substrate. The electroless plating can be applied to a fiber because it can form a plated film having a uniform film thickness and good adhesion even on a surface having a complicated structure. In addition, when the method is used, an electroconductive fiber There is an advantage that an electroconductive fiber excellent in durability and electromagnetic wave shielding effect can be obtained.

However, in order to attach electromagnetic wave shielding fibers by the electroless plating method to electronic devices or electronic components, it is necessary to use an electromagnetic wave shielding sheet or tape having an adhesive layer. As a general adhesive, it is preferable to bond the electromagnetic wave shielding fibers by electroless plating There was a disadvantage that it could not be done. Accordingly, the present invention is characterized in that an adhesive layer is formed of an adhesive composition having excellent adhesion with an electromagnetic wave shielding material to solve the above problem.

The polymer constituting the electromagnetic wave shielding fiber of the present invention is preferably a polyester polymer. The density of the electromagnetic wave shielding fiber is preferably from 40 to 180 g / m < 3 > and the thickness is preferably from 0.01 to 2.00 mm. When the density is less than 40 g / m 3 or the thickness is less than 0.01 mm, the electromagnetic wave shielding performance may deteriorate. If the density exceeds 180 g / m 3 or the thickness exceeds 2.00 mm, There is a problem.

The thickness of the release layer is not particularly limited, but is preferably in the range of 4.5 to 250 micrometers. If the thickness of the release layer exceeds 250 micrometers, it is not economical.

There is no particular limitation on the material used for the release layer, but a polyester-based material is preferable, and polyethylene terephthalate (PET) is more preferably used, and silicone-treated polyethylene terephthalate may be used to increase the releasability have. The polyethylene terephthalate has excellent mechanical properties and protects the adhesive layer. When the electromagnetic shielding sheet or the electromagnetic shielding tape according to the present invention is formed at the application site, the polyethylene terephthalate is easily released from the adhesive layer to facilitate the operation. The thickness of the release film can be adjusted as needed, and the thickness of the release paper can be adjusted between 4.5 and 250 탆.

Hereinafter, a method for producing the heat-peelable electromagnetic wave shielding sheet of the present invention will be described in detail.

The heat-peelable electromagnetic wave shielding sheet of the present invention can be produced by irradiating a monomer containing a (meth) acrylic acid ester monomer having an alkyl group of 1 to 20 carbon atoms, a polar monomer copolymerizable with the monomer and a photoinitiator under a nitrogen atmosphere, ≪ / RTI > Adding thermally expandable microspheres, additives, conductive particles, and a photoinitiator to the syrup, followed by stirring to prepare a pressure-sensitive adhesive composition; Applying the agitated pressure-sensitive adhesive composition on one side of the release film to form a pressure-sensitive adhesive layer; Shielding the electromagnetic wave shielding fibers on the adhesive layer; And UV-Zone, and curing the adhesive resin composition.

In the present invention, the method of applying the pressure-sensitive adhesive resin composition on the release film is a known method used in the production of the pressure-sensitive adhesive tape. In the present invention, a pressure-sensitive adhesive resin composition is coated on a release film with an applicator. In the present invention, the coating thickness of the pressure-sensitive adhesive resin composition may be adjusted depending on the use of the pressure-sensitive adhesive tape or the pressure-sensitive adhesive tape, and may be specifically from 5 to 500 탆.

The Ubiquity zone of the present invention will be described. Thereafter, the thus-obtained laminate is passed through a UV-curing zone and a curing step is carried out. The peak wavelength of ultraviolet rays upon irradiation with ultraviolet rays preferably has a range of 320 to 390 nm. In the embodiment of the present invention, the ultraviolet light irradiated to the ultraviolet-curing pressure-sensitive adhesive composition preferably has an illuminance of 20 mW / cm 2 or more, more preferably 25 mW / cm 2 or more. If the illuminance of the ultraviolet ray is less than 20 mW / cm 2, the polymerization reaction time becomes longer and the productivity may be lowered. In addition, the illuminance of the ultraviolet ray is preferably 200 mW / cm 2 or less. If the light intensity of the ultraviolet ray exceeds 200 mW / cm 2, the photopolymerization initiator is consumed abruptly, so that the polymer may have a lower molecular weight and the holding power may be lowered particularly at high temperatures.

According to a preferred embodiment of the present invention, the Ubite light source installed in the Ubiquitous zone is one or two of a Bulb lamp and an LED lamp. A bulb lamp can be installed at the front end of the U-BO zone and an LED lamp can be installed at the rear end. Alternatively, the type of the UV light source may alternatively be provided, that is, by providing a bulb lamp at the front end, an LED lamp at the middle end, and a bulb lamp at the rear end, the kind of the UV light source can be changed .

The number of UV light sources can be adjusted according to the work environment and needs. Generally, bulb lamps have low output per one, so dozens or even hundreds may be installed in the chamber. The output amount of the LED lamp is preferably 7,000 to 9,000 W, and the output amount of the bulb lamp is preferably 50 to 200 W. If the amount of each of the LED and Bulb is less than the lower limit value, the photopolymerization reaction is difficult to occur sufficiently. If the amount exceeds the upper limit value, the flowability of the adhesive resin composition becomes poor.

Hereinafter, a specific embodiment of the present invention will be described. The specific examples of the following examples are intended to be illustrative, and the scope of the present invention is not limited to the following examples.

≪ Example 1 >

An acrylic polymer having a carbon-carbon double bond (C = C bond) photopolymerized in 95 parts by weight of 2-ethylhexyl acrylate (hereinafter referred to as 2-EHA) and 5 parts by weight of acrylic acid , 25 parts by weight of thermally expandable microspheres (Matsumoto Microsphere F30D, manufactured by Matsumoto Yushi-Seiyaku Co., Ltd.) and 1.61 parts by weight of epoxy-based silane (A-187, Daew Coating Co., Ltd.) in 68.45 parts by weight of a prepolymer And 4.84 parts by weight of nickel powder (T-123, VALE) as conductive particles were mixed and homogeneously mixed. Then, 0.1 part by weight of 1-hydroxy-cyclohexyl-phenyl-ketone as a photopolymerization initiator (IRGACURE 184, BASF) To prepare a peelable conductive pressure-sensitive adhesive composition.

The heat-peelable conductive pressure-sensitive adhesive composition described above was applied to an exfoliated surface of a polyester film (XP-3BR, Toray Co., Ltd.) having a thickness of 100 탆 on one side of which was subjected to releasing treatment with a silicone type releasing agent, Thereby forming a coating layer. The thus obtained pressure-sensitive adhesive application layer was laminated with an electromagnetic wave shielding film (WD-270-NiCo, Azine Electron) having a density of 165 g / m 3 and a thickness of 0.18 mm to produce an LED lamp (output power 8,000 W, irradiation light quantity 4000 mj / (Wavelength: 320 to 390 nm, manufactured by Hoya Co.) to produce a heat peelable electromagnetic wave shielding sheet.

≪ Example 2 >

An electromagnetic wave shielding sheet was prepared in the same manner as in Example 1 except that electromagnetic wave shielding fibers (WD-250-NiCo, Azine Electron) having a density of 100 g / m 3 and a thickness of 0.11 mm were used as the electromagnetic wave shielding fibers .

≪ Example 3 >

An electromagnetic wave shielding sheet was prepared in the same manner as in Example 1, except that electromagnetic wave shielding fiber (SS-370-PCN, manufactured by Ajinetronics) having a density of 44.6 g / m 3 and a thickness of 0.035 mm was used. .

<Comparative Example>

(A-187, manufactured by Daou Coatings Co., Ltd.) was added to 93.45 parts by weight of a polymer (weight average molecular weight 500,000) polymerized with 95 parts by weight of 2-ethylhexyl acrylate (hereinafter referred to as 2-EHA) and 5 parts by weight of acrylic acid ) And 4.84 parts by weight of nickel powder (T-123, VALE) as conductive particles were mixed and uniformly mixed. Then, 0.1 part by weight of tetrad-X (Mitsubishi Gas Chemical Co., Inc.), an epoxy curing agent, Acrylic pressure-sensitive adhesive composition was prepared.

The above-described conductive acrylic pressure-sensitive adhesive composition was coated on an exfoliated surface of a polyester film (XP-3BR, Toray Co., Ltd.) having a thickness of 100 m on one side of which was subjected to releasing treatment with a silicone type releasing agent, Thereby forming a coating layer. The thus obtained pressure-sensitive adhesive application layer was laminated with an electromagnetic shielding functional polyester fiber (WD-270-NiCo, Azine Electron) having a density of 165 g / m 3 and a thickness of 0.18 mm and then an acrylic pressure- And cured to prepare an electromagnetic wave shielding sheet.

The properties and the like of the adhesive composition and the electromagnetic wave shielding sheet produced by the above Examples and Comparative Examples were confirmed by the following characteristic evaluation method.

&Lt; Property evaluation method &

1. Adhesion measurement

The heat-peelable electromagnetic wave shielding sheets obtained in Examples and Comparative Examples were cut into a shape having a width of 25 mm and a length of 100 mm to prepare specimens, the release paper was peeled off, the adhesive layer was placed on the SUS plate and left for 30 minutes. Adhesive force (gf / 25 mm) was measured under the conditions of a peeling speed of 300 mm / min and a peeling angle of 18 degrees. Conditions other than those described herein were measured according to ASTM D3330.

2. Heat resistance  Measure

The specimens prepared in the same manner as in the above adhesive force measurement method were allowed to stand under the temperature condition of 100 ° C for 30 minutes, and then the electromagnetic wave shielding sheet was peeled off from the SUS plate and the peelability was evaluated. The results were evaluated as follows.? Indicating that good peeling was possible without causing adhesive residue or cohesive failure and?, And peeling was not observed, or peeling occurred on the adherend after peeling.

3. Electrical resistance evaluation

The prepared shielding sheet and the copper plate were cut to a size of 100 mm x 100 mm to prepare a specimen. The release sheet on the adhesive surface of the shielding sheet was peeled off and then attached to a Cu substrate specimen to be tested by Hioki's test equipment (RM3544 ) Was used to measure the vertical electrical resistance.

Item Example 1 Example 2 Example 3 Comparative Example adhesiveness
(gf / 25 mm) 990 950 910 980 Peelability ○ ○ ○ × Electrical resistance
(Ω) 0.01 0.01 0.01 0.01

As can be seen from the results shown in Table 1, the electromagnetic wave shielding sheet of the present invention has a similar electromagnetic shielding performance and adhesive strength to those of the comparative example, but does not cause residue on the adherend or aggregate destruction during peeling, I can see the ease

Claims (6)

To 100 parts by weight of a resin syrup prepared by partially polymerizing a monomer containing 70 to 99 parts by weight of a (meth) acrylic acid ester monomer having an alkyl group having 1 to 20 carbon atoms and 1 to 30 parts by weight of a polar monomer copolymerizable with the monomer, An adhesive layer obtained by ultraviolet curing a pressure-sensitive adhesive composition comprising 15 to 75 parts by weight of thermally expandable microspheres, 3 to 10 parts by weight of conductive particles, 1 to 5 parts by weight of an additive and 0.01 to 10 parts by weight of a photoinitiator;
A release layer formed on one surface of the adhesive layer; And
And an electromagnetic wave shielding layer formed on the other surface of the adhesive layer,
The electromagnetic wave shielding layer is an electromagnetic wave shielding fiber produced by an electroless plating method,
Wherein the thermally expandable microspheres are microspheres having a thermally expandable material contained in a shell having elasticity, the thermally expandable material being selected from the group consisting of propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, , Isohexane, heptane and octane, and the shell is a homopolymer or copolymer of a compound selected from the group consisting of nitrile monomers, styrene monomers and amide monomers,
Wherein the adhesive layer and the adherend are peelable from each other by heating. delete delete Preparing a prepolymer in a syrup state by irradiating ultraviolet light to a monomer containing a (meth) acrylic acid ester monomer having an alkyl group of 1 to 20 carbon atoms, a polar monomer capable of copolymerizing with the monomer, and a photoinitiator in a nitrogen atmosphere;
Adding thermally expandable microspheres, additives, conductive particles, and a photoinitiator to the syrup, followed by stirring to prepare a pressure-sensitive adhesive composition;
Applying the agitated pressure-sensitive adhesive composition on one side of the release film to form a pressure-sensitive adhesive layer;
Shielding the electromagnetic wave shielding fibers on the adhesive layer;
And curing the pressure-sensitive adhesive resin composition through the UV-zone,
Wherein the thermally expandable microspheres are microspheres having a thermally expandable material contained in a shell having elasticity, the thermally expandable material being selected from the group consisting of propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, , Isohexane, heptane and octane, and the shell is a homopolymer or copolymer of a compound selected from the group consisting of nitrile monomers, styrene monomers and amide monomers,
The UV-light source is arranged in the order of LED-Bulb-LED, the output amount of the LED is 7,000 to 9,000 W, and the output amount of Bulb is 50 to 200 W. A method of manufacturing a peelable electromagnetic wave shielding sheet.
delete delete