JP2017059627A - Electromagnetic wave suppression sheet, electromagnetic wave suppression adhesive sheet arranged by use thereof, resin composition for electromagnetic wave suppression, and electromagnetic wave suppression layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic wave suppression sheet which is superior in the performance of suppressing electromagnetic waves over a wide frequency band while it is slim in thickness, and which is superior in flexibility and conductivity.SOLUTION: An electromagnetic wave suppression sheet [I] comprises: a resin composition including a styrene-based thermoplastic elastomer and an electromagnetic wave-suppressing substance. The styrene-based thermoplastic elastomer includes a styrene-based structural unit by 25-80 wt%.SELECTED DRAWING: Figure 1

Description

  The present invention provides an electromagnetic wave suppression sheet that has excellent electromagnetic wave suppression performance over a wide frequency range, even if it is thin, and is lightweight and excellent in flexibility and conductivity, and an electromagnetic wave suppression pressure-sensitive adhesive sheet using the same, The present invention relates to an electromagnetic wave suppressing composition and an electromagnetic wave suppressing layer containing the composition.

  In recent years, electronic devices such as personal computers, mobile phones, and tablet terminals have become widespread, and it is now possible to exchange information using these electronic devices not only at home and at work, but also indoors and outdoors. . However, these electronic devices are highly convenient, but there is a problem that unnecessary electromagnetic waves (noise) generated from the electronic devices adversely affect other electronic devices and electrical products. There are also concerns about the effects of electromagnetic waves on broadcasting, communications, and the human body.

  Therefore, various electromagnetic wave countermeasure members such as an electromagnetic wave absorber that absorbs unnecessary electromagnetic waves, an electromagnetic wave suppressor that reduces the generation of electromagnetic waves and prevents leakage to the outside, or a shield body that blocks external electromagnetic waves,・ It is proposed to be incorporated in electronic equipment.

  As such an electromagnetic wave countermeasure member, for example, a λ / 4 type electromagnetic wave absorber having a resistive film layer that is thin, lightweight, rich in flexibility, and has a surface resistivity variation within ± 10% has been proposed ( (See Patent Document 1). Since this resistance film layer is thin and rich in flexibility, even if an external force is applied to the electromagnetic wave absorber, it is not easily damaged. And it has the advantage that it is excellent in mechanical characteristics, such as bending resistance, sag resistance, and abrasion resistance.

JP 2003-289196 A

  By the way, with the miniaturization and high integration of electric / electronic devices, electromagnetic wave absorbers and electromagnetic wave suppressors used in these electric / electronic devices have been required to be further flexible and thin. Yes. For this reason, even in the λ / 4 type electromagnetic wave absorber of Patent Document 1 and the like, further flexibility and thinning have been studied. However, the λ / 4 type electromagnetic wave absorber has a structure on the back surface of the resistive film layer. It is necessary to provide a reflective layer made of metal on the side. For this reason, the method of suppressing electromagnetic waves is restricted by reflection, the manufacturing process becomes complicated, the flexibility as a whole is limited, and there is a limit to thinning. In addition, the λ / 4 type electromagnetic wave absorber has a problem that the frequency range in which the electromagnetic wave can be suppressed is narrow, and the effect can be obtained only at a specific frequency.

  On the other hand, in an electromagnetic wave suppression body that does not require a reflective layer, if the electromagnetic wave suppression layer is further thinned, the electrical resistance value of the electromagnetic wave suppression layer usually increases and the conductivity decreases, so that sufficient electromagnetic wave suppression performance is obtained. There is a problem that it becomes difficult to be done.

  The present invention has been made in view of such circumstances, and an electromagnetic wave suppression sheet having excellent electromagnetic wave suppression performance over a wide frequency range and having excellent flexibility and conductivity, even if the thickness is thin, An object of the present invention is to provide an electromagnetic wave suppressing pressure-sensitive adhesive sheet using the material, and further to provide an electromagnetic wave suppressing resin composition and an electromagnetic wave suppressing layer.

  In order to solve the above problems, the present inventors obtain an electromagnetic wave suppression sheet having excellent electromagnetic wave suppression performance that is flexible and does not impair electrical conductivity even when the thickness is reduced. The idea was that the physical properties of the base resin component are important. And as a result of further research, among the styrene thermoplastic elastomers, particularly those containing 25 to 80% by weight of styrene structural units are used in the resin composition, the electromagnetic wave suppression with the desired excellent performance. The inventors have found that a sheet can be obtained and have reached the present invention.

<Summary of the invention>
That is, the present invention comprises a resin composition (A) containing a styrene thermoplastic elastomer (a1) and an electromagnetic wave suppressing substance, and the styrene thermoplastic elastomer (a1) has 25 to 80 styrene structural units. The electromagnetic wave suppression sheet containing 1% by weight is the first gist.

  Moreover, this invention makes the 2nd summary the electromagnetic wave suppression adhesive sheet by which adhesive layer [II] is laminated | stacked on the single side | surface or both surfaces of the said electromagnetic wave suppression sheet [I].

  Furthermore, this invention contains a styrene-type thermoplastic elastomer (a1) and an electromagnetic wave suppression substance, and the said styrene-type thermoplastic elastomer (a1) contains 25-80 weight% of styrene-type structural units. The resin composition for use is a third summary, and the electromagnetic wave suppression layer containing the electromagnetic wave suppression resin composition is the fourth summary.

  In the electromagnetic wave suppression sheet of the present invention, the resin component used in the resin composition (A) is a specific styrene thermoplastic elastomer (a1) containing 25 to 80% by weight of a styrene structural unit. Even if the thickness is small, it has excellent electromagnetic wave suppression performance over a wide frequency range, excellent flexibility, and excellent conductivity.

  And since the electromagnetic wave suppression sheet | seat of this invention can make sheet | seat thickness very thin and is excellent also in a softness | flexibility, in a bending part, FPC (flexible printed wiring board), FFC (flexible flat cable), etc., Can be used without any problem. Therefore, it is possible to realize a significant reduction in weight of electrical equipment and electronic equipment that have taken countermeasures against electromagnetic waves.

  Moreover, according to the electromagnetic wave suppression pressure-sensitive adhesive sheet of the present invention, the above-described electromagnetic wave suppression sheet [I] having excellent performance can be easily obtained at a target place by using the pressure-sensitive adhesive layer [II] laminated thereon. Since it can be pasted, it has excellent workability.

  Furthermore, the pressure-sensitive adhesive layer [II] is laminated on one side or both sides of the electromagnetic wave suppression sheet [I] of the present invention, and one or both sides of the laminated body of the laminated electromagnetic wave suppression sheet [I] and pressure-sensitive adhesive layer [II]. The electromagnetic wave suppressing pressure-sensitive adhesive sheet obtained by laminating the support film [III] is preferable because the support film [III] reinforces the entire sheet and has excellent bending durability.

  And according to the resin composition for electromagnetic wave suppression of this invention, since an electromagnetic wave suppression layer can be easily obtained only by apply | coating this directly to the target part of an electric equipment or an electronic device, it is convenient. Moreover, the electromagnetic wave suppression layer comprising such an electromagnetic wave suppression resin composition can be obtained simply by directly applying the resin composition to the target portion, and the obtained layer is obtained from the present invention. Similar to the electromagnetic wave suppression sheet [I], even when the thickness is small, the electroconductivity is excellent, and the flexibility and the electromagnetic wave suppression performance are excellent.

It is explanatory drawing of one manufacturing method of the electromagnetic wave suppression sheet | seat of this invention. (A)-(c) is explanatory drawing of the other manufacturing method of the electromagnetic wave suppression sheet | seat of this invention. (A), (b) is explanatory drawing of the further another manufacturing method of the electromagnetic wave suppression sheet | seat of this invention. (A), (b) is explanatory drawing which shows the structure of the electromagnetic wave suppression adhesive sheet of this invention. (A), (b) is explanatory drawing which shows the other structure of the electromagnetic wave suppression adhesive sheet of this invention.

  Next, the form for implementing this invention is demonstrated in detail.

<Electromagnetic wave suppression resin composition (A), electromagnetic wave suppression layer and electromagnetic wave suppression sheet [I]>
The resin composition for electromagnetic wave suppression (A) of the present invention (hereinafter sometimes simply referred to as “resin composition (A)”) comprises a styrene-based thermoplastic elastomer (a1) and an electromagnetic wave suppressing substance, The styrenic thermoplastic elastomer (a1) contains 25 to 80% by weight of a styrenic structural unit.
And the electromagnetic wave suppression layer of this invention is a layer formed by containing the said resin composition for electromagnetic wave suppression (A).
The electromagnetic wave suppression sheet [I] of the present invention is formed of a resin composition (A) containing a styrene thermoplastic elastomer (a1) and an electromagnetic wave suppressing substance, and the styrene thermoplastic elastomer (a1). Must have a content of styrenic structural units of 25 to 80% by weight.

  The styrenic thermoplastic elastomer (a1) plays a role as a base polymer in the resin composition (A) of the present invention, and is an aromatic vinyl compound represented by styrene (hereinafter referred to as “styrene compound”). It has a hard segment (island part) consisting of polymer blocks and a soft segment (sea part) consisting mainly of polymer blocks of conjugated diene compounds (hereinafter referred to as “diene compounds”). Elastic properties are developed by the sea-island structure.

  The constitution of each block in the styrenic thermoplastic elastomer (a1) is as follows. When the hard segment is represented by X and the soft segment is represented by Y, a diblock copolymer represented by XY, XY- Examples thereof include a triblock copolymer represented by X or Y-XY, and a polyblock copolymer in which X and Y are alternately connected.

  As a monomer (styrene compound) used for forming a polymer block serving as a hard segment, styrene; α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, t- Alkyl styrene such as butyl styrene, 2,4-dimethyl styrene, 2,4,6-trimethyl styrene; alkoxy styrene such as methoxy styrene; halogenated styrene such as monofluoro styrene, difluoro styrene, monochloro styrene, dichloro styrene; vinyl naphthalene And vinyl compounds having an aromatic ring other than the benzene ring, such as vinyl anthracene, indene and acetonaphthylene; and derivatives thereof. The polymer block to be a hard segment may be a homopolymer block of these styrene compounds or a copolymer block in which two or more kinds are combined, and among them, a styrene homopolymer block is preferably used.

  The polymer block serving as the hard segment may be a copolymer obtained by copolymerizing a small amount of a monomer other than the styrene compound within a range not impairing the effects of the present invention. Examples of the copolymerizable monomer include butene, pentene, hexene. Olefins such as butadiene, diene compounds such as butadiene and isoprene, vinyl ether compounds such as methyl vinyl ether, and allyl ether compounds, and the copolymerization ratio is usually 10 mol% or less of the entire polymer block. Is desirable.

  The weight average molecular weight of the polymer block of the styrenic compound serving as the hard segment is usually 10,000 to 300,000, particularly 20,000 to 200,000, more preferably 50,000 to 100,000. The “weight average molecular weight” can be determined by a GPC (gel permeation chromatography) method (the same applies hereinafter).

  On the other hand, as a monomer (diene compound) used for forming a polymer block to be a soft segment, 1,3-butadiene, isoprene (2-methyl-1,3-butadiene), 2,3-dimethyl-1, Examples thereof include conjugated diene compounds such as 3-butadiene and 1,3-pentadiene, and isobutylene, and these may be used alone or in combination. Of these, a homopolymer block or copolymer block of isoprene, butadiene, and isobutylene is preferred, and a homopolymer block of butadiene or isobutylene is particularly preferred.

In addition, the polymer block of the diene compound may take a plurality of bond forms by polymerization. For example, in the case of butadiene, a butadiene unit (—CH ₂ —CH (CH═CH ₂ ) — by 1,2-bond is used. ) And 1,4-bonded butadiene units (—CH ₂ —CH═CH—CH ₂ —). Since these production ratios vary depending on the type of conjugated diene compound, it cannot be generally stated, but in the case of butadiene, the ratio of 1,2-bond production is usually in the range of 20 to 80 mol%.

  Moreover, the polymer block by the said diene type compound may hydrogenate a part or all of the double bond which remains in the polymer block from a heat resistant and weather resistant viewpoint. In this case, the hydrogenation rate is preferably 40 mol% or more, particularly preferably 45 mol% or more, and more preferably 55 mol% or more. In general, the upper limit is 99 mol%. The “hydrogenation rate (mol%)” is measured by nuclear magnetic resonance (NMR) (the same applies hereinafter).

  Further, in the polymer block, the hydrogenation rate of the vinyl bond portion based on the conjugated diene compound before hydrogenation is 50 mol% or more, preferably 70 mol% or more, particularly preferably 90 mol%. In general, the upper limit is 100 mol%. Here, “hydrogenation rate of vinyl bond portion” refers to the ratio of the amount of vinyl bonds hydrogenated to the amount of vinyl bonds before hydrogenation based on the conjugated diene compound incorporated in the polymer block.

  Regarding the hydrogenation rate of the aromatic double bond based on the styrenic structural unit in the polymer block, the hydrogenation rate is preferably 50 mol% or less, preferably 30 mol% or less, more preferably 20 mol% or less. .

By the above hydrogenation, for example, the butadiene unit of 1,2-bond of butadiene becomes a butylene unit (—CH ₂ —CH (CH ₂ —CH ₃ ) —), and the butadiene unit generated by the 1,4-bond is two. Two consecutive ethylene units (—CH ₂ —CH ₂ —CH ₂ —CH ₂ —) are formed, but usually the former is preferred.

  Furthermore, the polymer block to be the soft segment may be a copolymer obtained by copolymerizing a small amount of monomers other than the above-mentioned monomers within a range that does not impair the effects of the present invention. Examples thereof include olefins such as butene, pentene and hexene; vinyl ether compounds such as methyl vinyl ether; allyl ether compounds and the like, and the copolymerization ratio is usually 10 mol% or less of the entire polymer block.

  And the weight average molecular weight of the polymer block used as the said soft segment is 10,000-300,000 normally, Especially 20,000-200,000, Furthermore, the thing of 50,000-100,000 is used preferably.

  The styrenic thermoplastic elastomer (a1) of the present invention is obtained by obtaining a block copolymer having a polymer block of the styrene compound and a polymer block such as the diene compound, and then conjugating as necessary. It can be obtained by hydrogenating the double bond in the polymer block of the diene compound.

  First, as a method for producing a block copolymer having a polymer block of a styrene compound and a polymer block such as a diene compound, for example, an alkyl lithium compound or the like is used as an initiator in an inert organic solvent. And a method of sequentially polymerizing the monomer component to be the polymer block.

  Next, examples of the method for hydrogenating the block copolymer include a method using a reducing agent such as a borohydride compound, and a hydrogen reduction using a metal catalyst such as platinum, palladium, Raney nickel, and the like. it can.

  In the styrene thermoplastic elastomer (a1) of the present invention, a structural unit derived from a styrene compound (referred to as “styrene structural unit” in the present invention) constituting a polymer block serving as a hard segment The thermoplastic elastomer (a1) should be contained in an amount of 25 to 80% by weight. This is a major feature of the present invention.

  That is, if the content of the styrenic structural unit is too small, the conductivity of the obtained electromagnetic wave suppressing layer or electromagnetic wave suppressing sheet [I] is lowered and the electromagnetic wave suppressing effect is reduced. If the amount is too large, the flexibility of the obtained electromagnetic wave suppression layer and electromagnetic wave suppression sheet [I] is inferior, or the dispersibility of the electromagnetic wave suppressing substance is deteriorated. In the present invention, the “content of styrenic structural unit” can be measured by a nuclear magnetic resonance method (NMR).

  Among the styrenic thermoplastic elastomers (a1), particularly in terms of the conductivity, flexibility, and dispersibility of the electromagnetic wave suppressing substance of the obtained electromagnetic wave suppressing layer and electromagnetic wave suppressing sheet [I], the styrene structural unit The content of is preferably 28 to 75% by weight, more preferably 33 to 70% by weight.

The weight average molecular weight of the styrenic thermoplastic elastomer (a1) is usually 30,000 to 500,000, particularly 40,000 to 400,000, more preferably 50,000 to 30 from the viewpoints of heat resistance, mechanical strength, and flexibility. Many are preferably used. The styrene-based thermoplastic elastomer (a1) has a melt viscosity (ηB) at 220 ° C. and a shear rate of 122 sec ⁻¹ is usually 10 to 30000 Pa · s, particularly preferably 30 to 20000 Pa · s, Furthermore, the thing of 80-15000 Pa.s is used preferably.

  If the weight average molecular weight of the styrene-based thermoplastic elastomer (a1) is too large or the melt viscosity is too high, the dispersibility of the electromagnetic wave suppressing substance in the obtained electromagnetic wave suppressing layer or electromagnetic wave suppressing sheet [I] may be lowered. On the contrary, if the weight average molecular weight is too small or the melt viscosity is too low, the mechanical strength of the obtained electromagnetic wave suppression layer or electromagnetic wave suppression sheet [I] may be insufficient. In addition, the weight average molecular weight of a styrene-type thermoplastic elastomer (a1) is the value calculated | required on the basis of polystyrene using GPC.

  Further, in the present invention, the glass transition temperature of the styrenic thermoplastic elastomer (a1) can be measured by tan δ (loss tangent) peak temperature in dynamic viscoelasticity measurement, and the peak temperature is measured at two or more points. Sometimes it is done. When the peak temperature is one point, from the viewpoint of dispersibility of the electromagnetic wave suppressing substance, one measurement is performed at −25 ° C. to 150 ° C., preferably −0 ° C. to 130 ° C., more preferably 5 ° C. to 120 ° C. Is preferred. When the peak temperature is two or more points, from the viewpoint of flexibility, the first point is measured in the above temperature range, and the second point is -80 ° C to 80 ° C, preferably -70 ° C to 70 ° C. It is preferably measured at ° C, more preferably -60 ° C to 50 ° C.

  The glass transition temperature is a transition temperature resulting from the ratio of the conjugated diene to the styrene structural unit in the polymer chain of the styrene thermoplastic elastomer (a1), and the molecular weight of the styrene thermoplastic elastomer (a1). It is adjusted by the content of the styrenic structural unit.

  Examples of such a styrenic thermoplastic elastomer (a1) include styrene / butadiene block copolymer (SBS) using styrene and butadiene as raw materials, styrene / hydrogenated side chain double bond in the butadiene structural unit of SBS / Butadiene / butylene block copolymer (SBBS), styrene / ethylene / butylene block copolymer (SEBS) in which main chain double bonds are hydrogenated, and styrene / isoprene block copolymer using styrene and isoprene as raw materials ( SIPS), a styrene / isobutylene block copolymer (SIBS) using styrene and isobutylene as raw materials, and the like. Of these, hydrogenated styrene-based thermoplastic elastomers are preferable. For example, SBBS or SEBS in which double bonds of butadiene structural units are hydrogenated are preferably used.

  These commercially available products include, for example, “Tufprene”, “Asaprene T”, “Asaflex” manufactured by Asahi Kasei Chemicals, which is SBS, and “Tuftec (registered trademark, hereinafter the same) P series” manufactured by Asahi Kasei Chemicals, which is SBBS. SEBS, “Tough Tech H Series” manufactured by Asahi Kasei Chemicals Co., Ltd., and SIBS, “Shibustar” manufactured by Kaneka Corporation. Other commercially available products include “Clayton G”, “Clayton D”, “Califlex TR” manufactured by Shell Japan, “Septon”, “Hypler” manufactured by Kuraray, “DYNARON” manufactured by JSR, “ Examples thereof include “JSR-TR”, “JSR-SIS”, “Quintac” manufactured by Zeon Corporation, and “Electrified STR” manufactured by Denki Kagaku.

  Among these commercial products, Tuftec H1043 (SEBS, styrene content: 67% by weight, manufactured by Asahi Kasei Chemicals), Tuftec P5051 (SBBS, styrene content: 47% by weight, manufactured by Asahi Kasei Chemicals), DYNARON 8903P ( SEBS, styrene content: 35% by weight, manufactured by JSR Corporation) and the like are preferable. The “styrene content” refers to a content in which structural units derived from styrene are contained in the entire copolymer (hereinafter the same).

  In the resin composition (A) of the present invention, the styrenic thermoplastic elastomer (a1) may be used alone or in combination of two or more.

  Further, the base polymer of the resin composition (A) of the present invention is not necessarily composed of the styrene thermoplastic elastomer (a1), but other styrene thermoplastic elastomers having different physical properties or polyurethane resins. In addition, a part of thermosetting resin such as unsaturated polyester resin or epoxy resin may be used. However, the content ratio of other resin components is 10% by weight or less of the total resin components so that the effect of the styrene thermoplastic elastomer (a1) having a content of styrene structural units of 25 to 80% by weight is not impaired. It is preferred to stay.

  Next, as the electromagnetic wave suppressing substance contained in the resin composition (A) of the present invention together with the styrenic thermoplastic elastomer (a1), various conductive powders conventionally used as having an electromagnetic wave suppressing effect are used. Can be given. More specifically, for example, metal powders such as gold, silver, copper, aluminum, magnetic powder, and ferrite, metal oxide powders such as zinc oxide, tin oxide, and indium oxide, carbon black, graphite, and carbon nanotube (single Layer / double layer / multilayer type, cup stack type), carbon nanofibers, carbon nanocoils, carbon fibers, carbon nanohorns, conductive composite particles whose surface layer is coated with metal, and the like. Two or more kinds may be combined.

  When carbon nanotubes are used, the average diameter (diameter or cross-sectional diameter in a direction perpendicular to the axial direction) can be selected from about 0.5 nm to 1 μm, for example. In the case of single-walled carbon nanotubes, for example, In the case of a multi-walled carbon nanotube, it is, for example, about 5 to 300 nm. The average length of the carbon nanotube is, for example, about 1 to 1000 μm. Moreover, when using carbon nanofiber, the average diameter can illustrate 1-350 nm. Examples of carbon fibers include pitch systems made from heavy oil, by-product oil, coal tar, and the like, and PAN systems made from polyacrylonitrile.

  Moreover, instead of using conductive powder, when bubbles such as air are dispersed and contained in the resin composition (A) and electromagnetic waves are scattered by the bubbles, the bubbles become an electromagnetic wave suppressing substance.

  In this invention, it is preferable that content of an electromagnetic wave suppression substance is 5-60 weight part with respect to 100 weight part of total of the base polymer of a resin composition (A), and an electromagnetic wave suppression substance, More preferably, it is 8 ~. 55 parts by weight, particularly preferably 10 to 50 parts by weight. If the amount is too small, the desired electromagnetic wave suppression performance tends to be difficult to obtain. If the amount is too large, the strength of the obtained electromagnetic wave suppression layer or electromagnetic wave suppression sheet tends to decrease, and physical performance tends to decrease.

  These electromagnetic wave suppressing substances may be used alone or in combination of two or more, but among them, carbon materials such as carbon black (a2) and graphite (a3) may be used alone or in combination of two or more. It is preferable to use, and in particular, it is optimal to combine carbon black (a2) and graphite (a3). Carbon black (a2) and graphite (a3) are distinguished by the fact that carbon black (a2) is amorphous, whereas graphite (a3) is a crystal having a network structure. For this reason, the carbon black particles have a finer shape than the graphite particles.

As the carbon black (a2) that can be used in the present invention, those having excellent dispersibility and conductivity are preferably used. Therefore, the average particle diameter of the preferable carbon black (a2) is usually 1 to 500 nm, more preferably 5 to 300 nm, further desirably 10 to 100 nm, and particularly preferably 20 to 60 nm. That is, if the average particle size of the carbon black (a2) is too large, desired conductivity is difficult to obtain, and the electromagnetic wave suppressing effect tends to be reduced.
The above-mentioned “average particle diameter of carbon black (a2)” is obtained by observing and measuring primary particles constituting the carbon black aggregate with an electron microscope (the same applies hereinafter).

  Examples of such carbon black (a2) include commercially available products such as Seast S, conductive carbon black # 5500, # 4500, # 4400, # 4300, graphitized carbon black # 3855, # 3845, # 3800 (or more). , Manufactured by Tokai Carbon Co., Ltd.), # 3050B, # 3030B, # 3230B, # 3400B (manufactured by Mitsubishi Chemical Corporation), acetylene black (Denka Black, manufactured by Denki Kagaku Kogyo Co., Ltd.), BLACK PEARLS 2000, STERLING C, VULCAN P, VULCAN XC-72 (above, manufactured by Cabot Corporation), Ketjen Black EC300J, Ketjen Black EC600JD (above, manufactured by Lion Corporation), and the like.

  In addition, as the graphite (a3) that can be used in the present invention, those having excellent dispersibility and conductivity are preferably used as in the case of carbon black (a2). Therefore, the average particle diameter of the preferable graphite (a3) is usually 1 to 300 μm, preferably 3 to 200 μm, more desirably 5 to 100 μm, and particularly preferably 8 to 50 μm. The “average particle diameter of graphite (a3)” is determined by a laser diffraction particle size distribution measuring apparatus (the same applies hereinafter). If the average particle diameter of graphite (a3) is too large or too small, desired conductivity is difficult to obtain, and the electromagnetic wave suppression effect tends to decrease.

  Such graphite (a3) is obtained by refining, pulverizing and classifying natural graphite and artificial graphite, and the shape thereof is a plate having a length and width of 3 to 500 times the thickness. preferable. Here, the “plate shape” means a shape in which one direction is contracted, and may be, for example, a flat spherical shape or a scale shape.

  As said graphite (a3), as a commercial item, for example, SNE series, SNO series, SGP series, SGD series, SGX series, SGL series, SCN series, SCL series (above, the product made by SEC carbon company), scaly graphite powder (CP series, CB series, F # series), high purity graphite powder (ACP series, ACB series, SP series, HCP series), artificial graphite powder (PAG series, HAG series), earth graphite powder, exfoliated graphite powder , Spheroidized graphite powder (manufactured by Nippon Graphite Industry Co., Ltd.) and the like. Further, these commercially available products may be further pulverized and classified precisely.

  In the present invention, when the carbon black (a2) is used, the content thereof may be set to 15 to 60 parts by weight with respect to a total of 100 parts by weight of the base polymer and the electromagnetic wave suppressing substance of the resin composition (A). More preferably, it is 20-55 weight part, Most preferably, it is 25-50 weight part. That is, when the content of the carbon black (a2) is too small, the desired conductivity is difficult to obtain, and the electromagnetic wave suppression effect tends to decrease. When the content is too large, the strength of the electromagnetic wave suppression layer and the electromagnetic wave suppression sheet [I] obtained. Or the physical performance tends to decrease.

  Similarly, when the graphite (a3) is used, the content thereof is preferably 5 to 60 parts by weight with respect to a total of 100 parts by weight of the base polymer and the electromagnetic wave suppressing substance of the resin composition (A). More preferably, it is 8-55 weight part, Especially preferably, it is 10-50 weight part. That is, if the amount is too small, it is difficult to obtain desired conductivity, and the electromagnetic wave suppressing effect tends to be reduced. If the amount is too large, the strength of the obtained electromagnetic wave suppressing layer and electromagnetic wave suppressing sheet [I] may be decreased, resulting in physical performance. There is a tendency to decrease.

  Furthermore, in the present invention, when carbon black (a2) and graphite (a3) are used in combination, the state of filling conductive particles is improved as compared with the case where carbon black (a2) and graphite (a3) are used alone, respectively. Conductivity is easily obtained, and electromagnetic wave suppression performance is improved. The total content of both (a2) and (a3) is preferably 25 to 75 parts by weight, more preferably 100 parts by weight in total of the base polymer and the electromagnetic wave suppressing substance of the resin composition (A). 30 to 70 parts by weight, particularly preferably 40 to 60 parts by weight. If the total content of both (a2) and (a3) is too small, the desired electromagnetic wave suppression performance tends to be difficult to obtain. If it is excessive, the dispersibility decreases, and the resulting electromagnetic wave suppression layer or electromagnetic wave There exists a tendency for the physical performance to fall, for example, the intensity | strength of suppression sheet | seat [I] falls.

  When carbon black (a2) and graphite (a3) are used in combination, the content ratio (a2 / a3) of carbon black (a2) and graphite (a3) is 10/90 to 90/10 (weight ratio, below) The same is preferable, 15/85 to 85/15 is more preferable, 20/80 to 80/20 is further preferable, and 25/75 to 75/25 is particularly preferable. When the content ratio of both (a2) and (a3) is out of the above range, the electromagnetic wave suppression effect tends to be reduced.

  In addition to the above-mentioned specific styrene-based thermoplastic elastomer (a1) and an electromagnetic wave suppressing substance such as carbon black (a2) and graphite (a3), the resin composition (A) is necessary as well. Depending on the case, various optional components can be blended. Examples of such optional components include flame retardants (for example, melamine-coated ammonium polyphosphate, aluminum hydroxide, etc.), colorants such as organic pigments and inorganic pigments, light stabilizers, weathering stabilizers, mold release agents, and the like. .

  Preparation of the resin composition (A) using these components is performed, for example, with respect to the styrene-based thermoplastic elastomer resin (a1) and the electromagnetic wave suppressing substance, for example, volatile solvents such as methyl ethyl ketone (MEK), toluene, N, N -It is carried out by adding dimethylformamide and the like, kneading sufficiently, and uniformly dispersing them.

  The kneading can be performed using, for example, a high-speed disperser, a vertical disperser, a kneader, a ball mill, a three-roll mill, a jet mill, an impeller, and the like.

Thus, the electromagnetic wave suppression resin composition (A) of the present invention can be obtained.
And the electromagnetic wave suppression layer of this invention can be obtained using the resin composition material containing the said resin composition (A). For example, the resin composition material containing the resin composition (A) is directly applied by printing (screen printing, ink jet printing, etc.), dipping, or coating on various members, and drying. Can be obtained.
The “resin composition material containing the resin composition (A)” is intended to include the case where the entire resin composition material is made of the resin composition (A).

  Examples of the various members include wiring boards (FPC, rigid wiring boards, rigid flexible wiring boards, etc.), cables (FFC, etc.), housings, and the like. Moreover, an electromagnetic wave suppression layer can also be obtained by producing an electromagnetic wave suppression adhesive sheet as described below and then affixing it to a wiring board, a cable, a housing or the like.

  Next, the method to obtain electromagnetic wave suppression sheet [I] of this invention using the said resin composition (A) is demonstrated. Examples of the method include the following methods (first production method).

  That is, first, as shown in FIG. 1, on the support film [III], the solution of the resin composition (A) is applied using, for example, a doctor blade, the applied layer is dried, and the electromagnetic wave suppressing sheet [ I]. According to this manufacturing method, the electromagnetic wave suppression sheet [I] having a form in which the support film [III] is laminated on one side can be obtained.

  The electromagnetic wave suppression sheet [I] has a physical treatment such as a sandblast treatment or a physical treatment such as a flame treatment, a corona treatment, or a plasma treatment on the surface of the electromagnetic wave suppression sheet [I] in order to increase the adhesion with the adhesive layer [II] described later. It is preferable to perform chemical treatment or primer treatment.

  In the present invention, the support film [III] not only plays a role as a substrate during the production of the electromagnetic wave suppression sheet [I], but also reinforces the electromagnetic wave suppression sheet [I] by its own strength and flexibility. It serves as a guide. Therefore, the support film [III] is handled as it is integrally with the electromagnetic wave suppression sheet [I] without being removed from the electromagnetic wave suppression sheet [I] even after production unless there is a particular problem.

  The electromagnetic wave suppression sheet [I] thus obtained is a specific styrene in which the resin composition (A) used as a base thereof has a content of styrene structural units constituting the hard segment of 25 to 80% by weight. Since the thermoplastic elastomer (a1) is contained, even if the thickness is small, it has excellent electromagnetic wave suppression performance over a wide frequency range, excellent flexibility, and excellent conductivity. And since the sheet | seat thickness can be made very thin and it is excellent also in the softness | flexibility, it can be used for a bending part, FPC, FFC, etc. without trouble. Therefore, it is possible to realize a significant reduction in weight of electrical equipment and electronic equipment that have taken countermeasures against electromagnetic waves.

  From the viewpoint of reducing the weight of the electrical / electronic device, the thickness of the electromagnetic wave suppression sheet [I] (the thickness of the sheet alone not including the support film [III]) is set in the range of 5 to 1000 μm. More preferably, it is in the range of 8 to 500 μm, more preferably 10 to 200 μm, and particularly preferably 15 to 100 μm. If the thickness is too thin, the electromagnetic wave suppressing effect tends to be reduced, and if it is too thick, not only is it not preferable in terms of weight reduction, but also flexibility tends to decrease.

  Even if the electromagnetic wave suppression sheet [I] is very thin as described above, the support film [III] performs a reinforcing and guiding function. Therefore, the extremely thin electromagnetic wave suppression sheet [I] is used as an FPC. Even if it is attached to various substrates such as FFC or FFC, it is possible to reduce the weight of the electronic device without causing cracks or rigidity.

  In the above production method, as the support film [III], a commercially available product film may be used as it is, or a resin material may be applied and dried to obtain a film. Moreover, the same resin may be used for electromagnetic wave suppression sheet [I] and support film [III], and another resin may be used.

  The support film [III] may be a single layer or a multilayer, and as a material used for the support film [III], a conventionally known material can be appropriately selected and used depending on the application. Specifically, for example, cellophane, celluloid, synthetic paper, art paper, retroreflective sheet, polyethylene cloth, craft paper, OPP film, PET film, CPP film, or thermoplastic resin can be used. In addition, the support film [III] has a physical treatment such as a sand blast treatment, a physical treatment such as a flame treatment, a corona treatment, or a plasma treatment on the surface in order to enhance the adhesion with the adhesive layer [II] described later. It is preferable to perform chemical treatment or primer treatment.

  Examples of the resin material for forming the support film [III] include styrene thermoplastic elastomer resin, polyester resin, butyral resin, acrylic resin, epoxy resin, vinyl chloride resin, polyacetal resin, vinyl acetate resin, and fluororesin polyester. Examples thereof include a resin, a polyetherimide resin, a polyimide resin, and a polyphenylene sulfide resin. Among these, it is preferable to select any one of a polyester resin, a polyetherimide resin, a polyimide resin, a polyphenylene sulfide resin, or a styrene-based thermoplastic elastomer resin. Moreover, these may be used independently or may combine 2 or more types.

  And it is preferable that the weight average molecular weights of resin used as the said resin material are 50,000-1 million. That is, if the weight average molecular weight is too small, practical physical properties cannot be obtained. Conversely, if the weight average molecular weight is too large, the melt viscosity and the viscosity when dissolved in a solvent are too high. Tends to decrease. The glass transition temperature of the resin is preferably -20 ° C or higher and 90 ° C or lower, more preferably -10 ° C or higher and 50 ° C or lower. If it is lower than the lower limit, the obtained sheet may cause blocking.

  Moreover, the thickness of support film [III] has the preferable range of 3-200 micrometers, More preferably, it is 5-100 micrometers, More preferably, it is 8-50 micrometers, Most preferably, it is the range of 10-30 micrometers.

  Furthermore, the electromagnetic wave suppression sheet [I] (with the support film [III]) of the present invention can also be produced as follows (second production method). In this manufacturing method, as shown in FIG. 2A, first, an electromagnetic wave suppression sheet [I] is formed on the release liner 1 by applying and drying a solution of the resin composition (A). And after forming support film [III] on this electromagnetic wave suppression sheet [I] as shown in FIG.2 (b), as shown in FIG.2 (c), the peeling liner 1 was peeled off. The electromagnetic wave suppression sheet [I] with the support film [III] is formed.

  The release liner 1 is formed after the electromagnetic wave suppression sheet [I] is formed thereon, and then peeled off and removed, and a part of the electromagnetic wave suppression sheet [I] remains on the release liner 1 side. Any material can be used as long as it can be easily peeled off.

  Moreover, the electromagnetic wave suppression sheet [I] (with the support film [III]) of the present invention can also be produced as follows (third production method). In this manufacturing method, as shown in FIG. 3A, first, the electromagnetic wave suppression sheet [I] is formed on the release liner 1 by applying and drying the resin composition (A) solution, and the support film [I]. The binder resin layer 2 is applied to one side of [III], and the support film [III] is bonded to the electromagnetic wave suppression sheet [I] via the binder resin layer 2. And as shown in FIG.3 (b), the peeling liner 1 is peeled from the surface on the opposite side to the said bonding surface of electromagnetic wave suppression sheet [I], and electromagnetic wave suppression sheet with support film [III] [ I].

  Examples of the binder resin used for the binder resin layer 2 include (meth) acrylic resin (“(meth) acrylic” is a general term for acrylic and methacrylic, hereinafter the same), polyester resin, polyurethane resin, polystyrene resin, polypropylene. Resin, polyethylene resin, acrylonitrile / butadiene / styrene (ABS) resin, polycarbonate resin, epoxy resin, natural and synthetic cis-1,4-polyisoprene rubber, butyl rubber, halogenated butyl rubber, partially vulcanized butyl rubber, styrene / butadiene / Examples thereof include styrene (SBS) resin, styrene / isoprene / styrene (SIS) resin, styrene / ethylene / butylene / styrene (SEBS) resin, silicone rubber, chloroprene rubber, nitrile rubber, butadiene rubber and the like. These may be used alone or in combination of two or more.

  In this invention, 0.05-1000 N / cm is preferable and, as for the tensile strength of electromagnetic wave suppression sheet [I], More preferably, it is 0.1-500 N / cm. If the tensile strength is too low, it is not practical because the strength is poor, and if the tensile strength is too high, it tends to be too hard to obtain a flexible sheet. The tensile strength was measured according to JIS-K7127 at 23 ° C., 50% RH, and a tensile speed of 200 mm / min.

  In this invention, the elongation of electromagnetic wave suppression sheet [I] has the preferable range of 5-1000%, More preferably, it is the range of 10-50%. When the elongation is too low, the flexibility and followability of the obtained sheet tend to be lowered, and the impact resistance tends to be low. On the other hand, if it is too high, the mechanical stability decreases because the elongation is too large. The elongation was measured at 23 ° C., 50% RH, and a tensile speed of 200 mm / min in accordance with JIS-K7127.

  Moreover, the electromagnetic wave suppression sheet [I] of the present invention may be an electromagnetic wave suppression pressure-sensitive adhesive sheet in which an adhesive layer [II] is laminated on one side or both sides thereof. If the pressure-sensitive adhesive layer [II] is provided on the electromagnetic wave suppression sheet [I], the electromagnetic wave suppression sheet [I] is affixed and fixed to a target place at any time using the pressure-sensitive adhesive layer [II]. can do. And it is desirable for handling that the surface of the pressure-sensitive adhesive layer [II] is covered with a release liner [IV] as shown in FIGS. 4 (a) and 4 (b), for example. Further, even if the electromagnetic wave suppression sheet [I] is not applied using the adhesive layer [II], the adhesive layer [II] laminated on one or both sides thereof is used. Then, the above-mentioned support film [III] may be bonded together (see FIG. 5A). Furthermore, the support film [III] may be bonded using one pressure-sensitive adhesive layer [II], and the release liner [IV] may be bonded using the other pressure-sensitive adhesive layer [II]. See 5 (b)].

  As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer [II], those generally used as pressure-sensitive adhesives for pressure-sensitive adhesive sheets can be used. For example, acrylic resin-based pressure-sensitive adhesives, natural rubber and synthetic rubber Rubber adhesives such as SBS block copolymer adhesives and SIS block copolymer adhesives, block copolymer adhesives such as hydrogenated products, ethylene-vinyl acetate copolymer adhesives, polyvinyl ether resins -Based adhesives, silicone resin-based adhesives, and the like. Among them, an acrylic resin-based pressure-sensitive adhesive that is excellent in durability and weather resistance and has little dirt during handling is preferably used. These pressure-sensitive adhesives may be used alone or in combination of two or more.

  As such an acrylic resin-based pressure-sensitive adhesive, for example, an acrylic polymer obtained by polymerizing a carboxyl group-containing monomer and a (meth) acrylic acid alkyl ester monomer is preferably used.

  Examples of the carboxyl group-containing monomer include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and itaconic acid; dicarboxylic acids such as fumaric acid and maleic acid, and monoesters thereof.

  The (meth) acrylic acid alkyl ester monomer preferably has an alkyl group having about 4 to 12 carbon atoms. Specifically, n-butyl (meth) acrylate (“(meth) acrylate” Is a general term for acrylate and methacrylate, the same shall apply hereinafter), isobutyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, and the like. It is done.

  The form of these pressure-sensitive adhesives is not particularly limited. For example, a solvent-type pressure-sensitive adhesive, an emulsion-type pressure-sensitive adhesive, a hot-melt-type pressure-sensitive adhesive, a reactive pressure-sensitive adhesive, a photopolymerizable monomer-type pressure-sensitive adhesive, etc. Either form may be sufficient. There is no restriction | limiting in a coating means and a drying method, A well-known thing is employable. In addition, these pressure-sensitive adhesives may include cross-linking agents such as polyisocyanate compounds, aziridine compounds, metal chelate compounds, tackifiers, couplings, etc., as long as the object of the present invention is not impaired. Agent, filler, softener, plasticizer, surfactant, antioxidant (anti-aging agent), heat stabilizer, light stabilizer, ultraviolet absorber, colorant, antifoaming agent, flame retardant, antistatic agent, etc. 1 type or 2 types or more of these various additives can be mix | blended.

  As a method for applying the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer [II], a conventionally known method can be appropriately used. And it is preferable that the thickness of adhesive layer [II] is 3 micrometers-0.5 mm normally, especially 5-100 micrometers, Furthermore, it is preferable that it is 10-50 micrometers. If the thickness of the pressure-sensitive adhesive layer [II] is too thin, there is a tendency that the adhesiveness and the unevenness followability are insufficient, and conversely, if it is too thick, it is not preferable in terms of weight reduction. Moreover, although the tackiness no longer improves, the cost tends to be high.

  In order to obtain a laminate in which the pressure-sensitive adhesive layer [II] is laminated on the electromagnetic wave suppression sheet [I] and the release liner [IV] is laminated thereon, for example, first, on the release liner [IV]. Examples include a method (first method) in which an adhesive layer [II] is formed by applying and drying an adhesive, and an electromagnetic wave suppression sheet [I] is bonded thereon. As another method, a pressure-sensitive adhesive is applied and dried on the electromagnetic wave suppression sheet [I] to form a pressure-sensitive adhesive layer [II], and a release liner [IV] is bonded thereon (second method). ) Etc.

  As the release liner [IV], when the release liner [IV] is peeled from the pressure-sensitive adhesive layer [II], the release liner [IV] can be easily formed at the interface of the release liner [IV] in contact with the pressure-sensitive adhesive layer [II]. ] And the pressure-sensitive adhesive residue is required to be small on the release surface of the release liner [IV]. The level at which peeling can be easily made here is generally 180 ° peel adhesive strength (measured according to JIS-Z0237 at a peeling speed of 300 mm / min) of 0.005 N / 50 mm or more and 5 N / 50 mm. It means the following.

  As such a release liner [IV], for example, a material obtained by coating a silicone-based or non-silicone-based release agent on various plastic films or paper such as polyethylene terephthalate or oriented polypropylene is preferably used. Commercially available release papers include, for example, film biner series, bina sheet series (manufactured by Fujimori Kogyo Co., Ltd.), Tosero Separator SP series (manufactured by Tosero Co., Ltd.), Smithies series (manufactured by Sumika Kogyo Co., Ltd.), and separate paper. (Manufactured by Shinomura Chemical Co., Ltd.).

  Moreover, when preparing release liner [IV], as a support base material of release liner [IV], what kind of material will be used if it can play the role as a reinforcement layer with respect to the whole. Good. For example, a film or sheet made of a thermoplastic resin, and paper can be mentioned. More specifically, polyethylene resins such as high density polyethylene, low density polyethylene, and linear low density polyethylene, polypropylene, poly- Polyolefin resins such as 4-methylpentene-1; various polyamide resins (so-called “nylon” or the like); polyester resins such as polyethylene terephthalate; styrene resins such as polystyrene; films made of polyvinyl chloride resins or Examples of the paper include semi-bleached paper, high-quality paper, and glassine paper. These may be used alone or in combination of two or more.

  The thickness of the support substrate is preferably 10 to 300 μm, more preferably 25 to 200 μm, and still more preferably 50 to 150 μm from the viewpoint of making the whole thinner. If the thickness is too thin, the strength of the release liner [IV] tends to decrease, and if it is too thick, the punching processability tends to decrease or the cost increases.

  In addition, it is preferable that the thickness of the electromagnetic wave suppression adhesive sheet provided with the adhesive layer [II] is 5 to 1500 μm, more preferably 10 to 10 μm in total, of the electromagnetic wave suppression sheet [I] and the adhesive layer [II]. It is 500 μm, more preferably 20 to 100 μm. If the thickness is too thin, the punching processability tends to be reduced or the release liner [IV] tends to be torn, and if it is too thick, not only is the weight reduction unfavorable, but the cost tends to increase. There is.

  Even when the support film [III] or the release liner [IV] is provided on the pressure-sensitive adhesive layer [II] of the electromagnetic wave suppression pressure-sensitive adhesive sheet, the overall thickness is preferably 10 to 2000 μm, more preferably. Is 20 to 800 μm, more preferably 50 to 300 μm.

  As described above, the electromagnetic wave suppressing adhesive sheet can also be set to have a small overall thickness. Therefore, like the electromagnetic wave suppressing sheet [I], the inner and outer surfaces of the casing of the electric / electronic device have complicated shapes and bent portions. Or a wiring board (FPC, rigid flexible substrate, rigid substrate, etc.), cable (single wire, stranded wire, shielded wire, flat cable, FFC, etc.) and the like can be used without any trouble. Therefore, it is possible to realize a significant reduction in weight of electrical / electronic devices that have taken countermeasures against electromagnetic waves.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

[Examples 1-16, Comparative Examples 1-3]
Materials having compositions shown in Tables 1 to 3 below were kneaded using a three-roll mill to obtain a resin composition. Except in the case of Comparative Example 2, the base polymer (a1) was dissolved in toluene for dissolution and then subjected to kneading. The obtained resin composition was applied to the easy-adhesion-treated surface of the support film [III] (Easy-adhesion-treated PET film: Teijin Tetron film 25 μm thick HPE, manufactured by Teijin DuPont Films) similarly shown in Tables 1 to 3. The film was spread coated and dried at 80 ° C. for 5 minutes to form a 40 μm-thick electromagnetic wave suppression sheet [I] (with support film [III]).

  On the other hand, an acrylic pressure-sensitive adhesive composition (2-ethylhexyl acrylate / butyl acrylate / acrylic acid copolymer [weight ratio = 10 /) on a release liner [IV] (SLK-80KCT, manufactured by Sumika Kogyo Co., Ltd.). 88/2] 50% by weight ethyl acetate solution [weight average molecular weight 650,000, glass transition temperature -55 ° C.] (first component) and Tosoh Coronate L55E (second component) A mixture of two components of 100 parts by weight / 2 parts by weight) was applied so that the thickness after drying was about 25 μm. Then, the pressure-sensitive adhesive dried at 100 ° C. for 1 minute with a hot air circulation dryer is bonded onto the electromagnetic wave suppression sheet [I] using a laminate roll, and aged for 7 days under the conditions of 23 ° C. and 65% RH. As a result, an adhesive layer [II] was formed, and an electromagnetic wave suppressing adhesive sheet (with adhesive layer [II] and release liner [IV]) was obtained.

[Examples 17 and 18]
In Example 1, the thickness of the electromagnetic wave suppression sheet [I] was changed from 40 μm to 10 μm in Example 17. In Example 18, the thickness was changed to 100 μm. Other than that was carried out similarly to Example 1, and obtained electromagnetic wave suppression sheet [I] and an electromagnetic wave suppression adhesive sheet. These are also shown in Table 3 in the same manner as in Example 1.

[Examples 19 and 20]
In Example 1, a 25 μm-thick PET film (HPE, manufactured by Teijin DuPont Films) was used as the support film [III], but in Example 19, a 25 μm-thick polyimide film (100H, manufactured by Toray DuPont) was used. It was. Moreover, in Example 20, it changed into the 9-micrometer-thick PPS film (Torelna # 9-3030, Toray Industries, Inc.). Other than that was carried out similarly to Example 1, and obtained electromagnetic wave suppression sheet [I] and an electromagnetic wave suppression adhesive sheet. These are also shown in Table 3 in the same manner as in Example 1.
In Tables 1 to 3 below, details of each material used are shown below.

<Base polymer (a1)>
・ Styrenic thermoplastic elastomer 1: Tuftec H1043
(SEBS, styrene content: 67% by weight, manufactured by Asahi Kasei Chemicals Corporation)
-Styrenic thermoplastic elastomer 2: DYNARON 8903P
(SEBS, styrene content: 35% by weight, manufactured by JSR)
Styrenic thermoplastic elastomer 3: Tuftec P5051
(SBBS, styrene content: 47% by weight, manufactured by Asahi Kasei Chemicals Corporation)
-Styrenic thermoplastic elastomer 4: TR2250
(SBS, styrene content: 52% by weight, manufactured by JSR)
Styrenic thermoplastic elastomer 5: Tuftec H1052
(SEBS, styrene content: 20% by weight, manufactured by Asahi Kasei Chemicals Corporation)
Polyester resin: Polyester MSP-640 (solid content about 23% by weight,
(Weight average molecular weight about 10,000, glass transition temperature 37 ° C, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
Styrene (ST) / butyl acrylate (BA) copolymer:
ST / BA = 50/50 (weight ratio) methyl ethyl ketone (MEK) -toluene solution (solid content about 33% by weight, weight average molecular weight about 340,000, glass transition temperature 2 ° C.)

<Carbon black (a2)>
・ Carbon black 1: Ketjen black EC300J (manufactured by Lion)
Average particle size 40nm
・ Carbon black 2: Ketjen black EC600JD (manufactured by Lion)
Average particle size 34nm
Carbon black 3: # 3030B (Mitsubishi Chemical Corporation)
Average particle size 55nm

<Graphite (a3)>
Graphite 1: UP-15N (Nippon Graphite Industries Co., Ltd.)
Average particle size 15μm
Graphite 2: CGB-10 (Nippon Graphite Industry Co., Ltd.)
Average particle size 10μm
・ Graphite 3: PAG-5 (manufactured by Nippon Graphite Industry Co., Ltd.)
Average particle size 30μm

<Dispersant>
-High molecular weight polyester acid amide amine salt dispersant: Disparon DA703-50
(Made by Enomoto Kasei)

  The following evaluation items were measured and evaluated for the example product and the comparative example product thus obtained, and the results are shown in Tables 4 to 6 below.

[Flexibility]
In accordance with JIS-P8115, the produced electromagnetic wave suppression sheet [I] was bent 10,000 times. Then, the shape of the wrinkles and cracks was observed by observing the surface state after bending, and evaluated according to the following criteria.
○: No wrinkles or cracks on the surface.
Δ: Slight wrinkles on the surface and no cracks.
X: Wrinkles are clearly seen on the surface and cracks are generated.

[Adhesive force]
In accordance with JIS-Z0237, the prepared electromagnetic wave suppression adhesive sheet is pressure-bonded to a mirror-finished one with stainless steel plate 304, and a 180 degree peeling test after 24 hours is performed at 23 ° C. and 50% RH, and the adhesive strength is measured. did.

[Surface resistivity]
Based on JIS-K7194, the surface resistivity of the surface of the electromagnetic wave suppression sheet [I] was measured by a four-terminal four-probe method.

[Radiation suppression rate]
In accordance with IEC62431, a vector network analyzer and a horn antenna were used for radio wave transmission and reception antennas, and the distance between the antennas was set to 50 cm. An electromagnetic wave suppression adhesive sheet was installed, and the transmission coefficient S21 was measured by a free space method in an anechoic chamber. Then, the electromagnetic wave suppression adhesive sheet was removed, S21 of the spacer alone was measured in the same manner as described above, and the radiation suppression rate was determined from the difference of S21 with and without the electromagnetic wave suppression adhesive sheet. The value of the radiation suppression rate is not a value that is generally determined because it depends on the generated frequency and its intensity, but it is preferably 10 dB or more at both frequencies of 2.4 G to 2.5 GHz and 5 G to 6 GHz. .

[Transmission attenuation factor]
According to IEC62333, an electromagnetic wave suppression adhesive sheet was affixed to the microstrip line, the reflection coefficient S11 and the transmission coefficient S21 were measured with a vector network analyzer, and the transmission attenuation rate Rtp value was obtained. The value of the transmission attenuation factor is not a value that is generally determined because it depends on the generated frequency and its strength, but it is preferably 20 dB or more at both frequencies of 1 G to 3 GHz and 5 G to 6 GHz.

  From the above results, it can be seen that the example product obtained excellent evaluation for any item, while the comparative example product was inferior in evaluation for most items.

  The electromagnetic wave suppression layer, the electromagnetic wave suppression sheet, and the electromagnetic wave suppression adhesive sheet of the present invention are excellent in electromagnetic wave suppression performance, are flexible, and do not crack or become rigid even when used in a bent portion, FPC, or FFC.・ We can reduce the weight of electronic equipment. In particular, the electromagnetic wave suppression sheet and the electromagnetic wave suppression adhesive sheet of the present invention can be used by being attached to a wiring board (FPC, rigid wiring board, rigid flexible wiring board, etc.), a cable (FFC, etc.), a housing, and the like. Moreover, the electromagnetic wave suppression layer of this invention can be directly formed and used for these members using the resin composition (A) of this invention.

Claims (12)

  It consists of a resin composition (A) containing a styrenic thermoplastic elastomer (a1) and an electromagnetic wave suppressing substance, and the styrenic thermoplastic elastomer (a1) contains 25 to 80% by weight of a styrenic structural unit. There is an electromagnetic wave suppression sheet.   The electromagnetic wave suppression sheet according to claim 1, wherein the styrene thermoplastic elastomer (a1) is a hydrogenated styrene thermoplastic elastomer.   The electromagnetic wave suppressing sheet according to claim 1 or 2, comprising carbon black (a2) as the electromagnetic wave suppressing substance.   The electromagnetic wave suppression sheet according to any one of claims 1 to 3, comprising graphite (a3) as the electromagnetic wave suppression substance.   As an electromagnetic wave suppressing substance, carbon black (a2) and graphite (a3) are contained, and the content ratio (a2 / a3) of carbon black (a2) and graphite (a3) is 10/90 to 90/10 (weight ratio). The electromagnetic wave suppression sheet according to any one of claims 1 to 4, wherein the electromagnetic wave suppression sheet is provided.   The electromagnetic wave suppressing sheet according to any one of claims 1 to 5, wherein the electromagnetic wave suppressing sheet has a thickness of 5 to 1000 µm.   An electromagnetic wave suppressing pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive layer [II] is laminated on one or both sides of the electromagnetic wave suppressing sheet [I] according to any one of claims 1 to 6.   The adhesive layer [II] is laminated on one side or both sides of the electromagnetic wave suppression sheet [I], and the support film [III is provided on one side or both sides of the laminated body of the laminated electromagnetic wave suppression sheet [I] and the adhesive layer [II]. ] Is laminated | stacked, The electromagnetic wave suppression adhesive sheet of Claim 7 characterized by the above-mentioned.   The pressure-sensitive adhesive layer [II] is laminated on one side or both sides of the electromagnetic wave suppression sheet [I], and the release liner [IV] is laminated on the exposed surface of the pressure-sensitive adhesive layer [II]. The electromagnetic wave suppression adhesive sheet according to 7 or 8.   The electromagnetic wave suppressing pressure-sensitive adhesive sheet according to any one of claims 7 to 9, wherein the electromagnetic wave suppressing pressure-sensitive adhesive sheet has a thickness of 5 to 1500 µm.   A styrenic thermoplastic elastomer (a1) and an electromagnetic wave suppressing substance are contained, and the styrenic thermoplastic elastomer (a1) contains 25 to 80% by weight of a styrenic structural unit. An electromagnetic wave suppressing resin composition.   An electromagnetic wave suppressing layer comprising the electromagnetic wave suppressing resin composition according to claim 11.

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