WO2019082634A1 - Electromagnetic wave absorbing composition and electromagnetic wave absorber - Google Patents

Electromagnetic wave absorbing composition and electromagnetic wave absorber

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Publication number
WO2019082634A1
WO2019082634A1 PCT/JP2018/037539 JP2018037539W WO2019082634A1 WO 2019082634 A1 WO2019082634 A1 WO 2019082634A1 JP 2018037539 W JP2018037539 W JP 2018037539W WO 2019082634 A1 WO2019082634 A1 WO 2019082634A1
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WIPO (PCT)
Prior art keywords
electromagnetic wave
antimony
wave absorbing
tin oxide
doped tin
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PCT/JP2018/037539
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French (fr)
Japanese (ja)
Inventor
服部　琢磨
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株式会社巴川製紙所
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Publication of WO2019082634A1 publication Critical patent/WO2019082634A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G30/00—Compounds of antimony
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K9/00—Use of pretreated ingredients
    • C08K9/02—Ingredients treated with inorganic substances
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L101/00—Compositions of unspecified macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
    • C08L33/04—Homopolymers or copolymers of esters
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields

Definitions

  • the present invention relates to an electromagnetic wave absorbing composition and an electromagnetic wave absorber, and more particularly to an electromagnetic wave absorbing composition and an electromagnetic wave absorber for preventing electromagnetic wave interference in a GHz band.
  • the electromagnetic wave absorber for this purpose has an electromagnetic wave absorbing layer with a predetermined complex relative dielectric constant as a type that absorbs only a specific frequency, an electromagnetic wave reflection layer on one side with a predetermined thickness according to the target frequency.
  • an electromagnetic wave absorber of the type that absorbs electromagnetic waves over a relatively wide frequency band using so-called matched electromagnetic wave absorbers provided and soft magnetic powder or the like.
  • the matching type electromagnetic wave absorber controls the amplitude and the phase so that the electromagnetic wave reflected on the surface of the electromagnetic wave absorption layer and the electromagnetic wave reflected and returned from the interface between the electromagnetic wave reflection layer on the back surface and the electromagnetic wave absorption layer cancel each other.
  • the relationship between the real part and the imaginary part of the complex relative permittivity of the electromagnetic wave absorption layer in the case of no reflection when the electromagnetic wave is vertically incident is d / ⁇ (d: thickness of the electromagnetic wave absorption layer, ⁇ : wavelength of the electromagnetic wave It is known to change according to).
  • the matching type millimeter-wave absorbing sheet of Patent Document 1 uses conductive needle-like titanium oxide, it is said that electromagnetic wave absorption performance is anisotropic when it is sheeted by applying a shearing force such as coating or drawing. I had a problem.
  • mold millimeter-wave absorption sheet of patent document 2 contains carbon black, it is necessary to adjust the addition amount of carbon black, and the thickness of an electromagnetic wave absorption layer according to the frequency to match. That is, since the electromagnetic wave absorption layer which mix
  • the present invention provides an electromagnetic wave absorbing composition and an electromagnetic wave absorber capable of efficiently absorbing an electromagnetic wave in the GHz band having little frequency dependency in the imaginary part of dielectric constant without generating anisotropy in the electromagnetic wave absorption performance. Intended to be provided.
  • the present inventors have found that the inclusion of specific fine particles in the resin composition makes it possible to obtain a matched electromagnetic wave absorber capable of efficiently absorbing electromagnetic waves in the GHz band.
  • the present invention has been achieved.
  • the present invention (1) is an electromagnetic wave absorbing composition comprising antimony-doped tin oxide-coated mica or antimony-doped tin oxide-coated talc and a resin composition.
  • the present invention (2) is that the resin composition is an acrylic resin, and any one selected from an epoxy acrylate having a vinyl group, a urethane acrylate, an ester acrylate, a butadiene acrylate, a silicone acrylate, and an amino resin acrylate.
  • It is an electromagnetic wave absorptive composition as described in the said invention (1) characterized by including.
  • the present invention (3) is an electromagnetic wave absorber characterized in that the electromagnetic wave absorbing layer composed of the electromagnetic wave absorbing composition according to the invention (1) or the invention (2) and an electromagnetic wave reflecting layer are laminated. is there.
  • FIG. 16 is a graph showing the relationship between the number of real terms and the imaginary term in each frequency band of the electromagnetic wave absorbers in Examples 1 to 6.
  • FIG. 15 is a graph showing the return loss of the electromagnetic wave absorber in Example 3.
  • 21 is a graph showing the return loss of the electromagnetic wave absorber in Example 7.
  • 21 is a graph showing the return loss of the electromagnetic wave absorber in Example 8.
  • FIG. 21 is a graph showing the return loss of the electromagnetic wave absorber in Example 9.
  • the electromagnetic wave absorbing composition of the present invention contains antimony-doped tin oxide-coated mica or antimony-doped tin oxide-coated talc, and a resin composition.
  • the resin composition includes a resin in a broad sense including rubber, and the kind thereof is not particularly limited, and in view of physical properties according to the application, for example, strength, heat resistance, moldability and the like, as appropriate It is selected.
  • chloroprene rubber chlorosulfonated polyethylene rubber, chlorinated polyethylene rubber, ethylene / ⁇ -olefin rubber, ethylene / propylene rubber, silicone rubber, acrylic rubber, fluororubber, styrene / butadiene rubber, rubber such as isoprene rubber, etc.
  • Thermoplastic resins, silicone resins, phenol resins, urea resins, thermosetting resins such as epoxy resins, and various thermoplastic elastomers such as urethane resins, amide resins and ester resins can be used.
  • these 2 or more types can also be mixed and used as needed.
  • thermoplastic resin examples include polyolefin resins (eg, polyethylene, polypropylene, ethylene / vinyl acetate copolymer, etc.), vinyl chloride resin, polystyrene resins (polystyrene, acrylonitrile / styrene copolymer, methyl methacrylate / styrene) Copolymers, acrylonitrile-butadiene-styrene copolymers, etc.), acrylic resins, vinyl acetate resins, silicone resins, fluorine resins, polyester resins, polyamide resins, polycarbonate resins, etc. may be mentioned.
  • polyolefin resins eg, polyethylene, polypropylene, ethylene / vinyl acetate copolymer, etc.
  • vinyl chloride resin polystyrene resins (polystyrene, acrylonitrile / styrene copolymer, methyl methacrylate / st
  • acrylic resins are preferable.
  • the acrylic resin epoxy acrylate having vinyl group, urethane acrylate, ester acrylate, butadiene acrylate, silicone acrylate, amino resin acrylate is preferably used, and more preferably, acrylic oligomer having about 2 to 20 repeating units.
  • urethane acrylate having a weight average molecular weight of 500 to 10,000 and a viscosity of 3,000 to 500,000 mPa ⁇ s / 25 ° C can easily be applied without solvent. It is more preferable in that it can be done.
  • a weight average molecular weight is a value measured using gel permeation chromatography (made by JASCO Corporation) based on JISK7252, and a viscosity is a value measured using an E-type viscometer. is there.
  • the electromagnetic wave absorbing composition may contain a polymerization initiator.
  • a polymerization initiator although a well-known thing can be used, an organic peroxide is preferable.
  • the organic peroxide is preferable in that the temperature at which the acrylic resin composition can be polymerized and cured without a solvent can be freely set in a temperature range from normal temperature to about 300 ° C.
  • organic peroxide examples include methyl ethyl ketone peroxide, cyclohexane peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, methylacetoacetate peroxide, acetylacetone peroxide, 1,1-bis (t- Butylperoxy) -3,3,5 trimethylhexane, 1,1-bis (t-butylperoxy) -cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl-4,4- Bis (t-butylperoxy) barate, 2,2-bis (t-butylperoxy) butane, t-butylhydroperoxide, cumene hydroperoxide, di-isopropylbenzene hydroperoxide, p-menthane hydroperoxade I 2,5-Dimethylhexane-2,5-dihydroperoxide,
  • the mass ratio represented by the resin composition / polymerization initiator in the electromagnetic wave absorbing composition is preferably 10 to 2000, more preferably 20 to 1000, and still more preferably 33 to 200. If the mass ratio is more than 2000, the curing reaction becomes insufficient, and when left at a high temperature for a long time, the weight reduction of the remaining uncured component causes shrinkage of the electromagnetic wave absorbing composition, The electromagnetic wave absorption performance may deviate from a desired frequency band. When the ratio is less than 10, the curing shrinkage of the electromagnetic wave absorbing composition may be increased, which may make it difficult to control the layer thickness when producing an electromagnetic wave absorber.
  • the content of the resin composition and the polymerization initiator in the electromagnetic wave absorbing composition for obtaining the most ideal electromagnetic wave absorbing performance can be arbitrarily determined by the frequency of the electromagnetic wave for absorption and the complex relative dielectric constant corresponding thereto. You should decide.
  • the electromagnetic wave absorbing composition of the present invention contains antimony-doped tin oxide-coated mica or antimony-doped tin oxide-coated talc (hereinafter, antimony-doped tin oxide-coated mica and antimony-doped tin oxide-coated talc are generically called tin-coated articles ).
  • the antimony-doped tin oxide-coated mica for example, a hydrochloric acid aqueous solution of tin chloride and an alkaline aqueous solution are simultaneously added to an aqueous solution in which mica powder is suspended, and tin hydrate is deposited by hydrolysis and subsequently coated in this solution Simultaneously add a mixed aqueous solution of antimony chloride and antimony chloride and an aqueous alkali solution, and heat and calcinate tin hydrate containing antimony hydrate coprecipitated on the tin hydrate-coated mica powder to oxidize It can be obtained by forming an antimony-doped tin oxide layer.
  • an antimony oxide-doped tin oxide layer is formed on the surface of talc powder by using talc powder instead of mica powder. It can be obtained by Since the tin coating in the present invention has a flat shape of mica and talc, it is less likely to cause anisotropy in the electromagnetic wave absorption performance as compared with the conductive needle-like titanium oxide conventionally used.
  • the electromagnetic wave absorbing composition may contain at least one of antimony-doped tin oxide-coated mica and antimony-doped tin oxide-coated talc. That is, the electromagnetic wave absorbing composition may contain only antimony-doped tin oxide-coated mica, or may contain only antimony-doped tin oxide-coated talc, or antimony-doped tin oxide-coated mica and antimony-doped tin oxide-coated talc Both may be contained.
  • the antimony-doped tin oxide-coated mica and the antimony-doped tin oxide-coated talc are both contained in the electromagnetic wave absorbing composition
  • the antimony-doped tin oxide is contained in the total amount of the antimony-doped tin oxide-coated mica and the antimony-doped tin oxide-coated talc
  • the coated mica content is preferably 15 to 40% by mass.
  • antimony-doped tin oxide-coated mica or antimony-doped tin oxide-coated talc trade names of Iriotec (registered trademark) 7310, Iriotec (registered trademark) 7315, Iriotec (registered trademark) 7320, Iriotec (trademark) manufactured by Merck & Co. Registered 7325, Iriotec (registered trademark) 7330, Iriotec (registered trademark) 7340 and the like are commercially available.
  • the content of the tin coating in the electromagnetic wave absorbing composition is preferably 10 to 60 parts by mass, more preferably 30 to 40 parts by mass with respect to 100 parts by mass of the resin composition. If it is less than 10 parts by mass, it is difficult to obtain sufficient electromagnetic wave absorption performance, and if it is more than 60 parts by mass, it is also difficult to obtain sufficient electromagnetic wave absorption performance.
  • a flame retardant In the electromagnetic wave absorbing composition, a flame retardant, a flame retardant auxiliary, a filler, a releasing agent, a surface treating agent, a viscosity controlling agent, a plasticizer, an antibacterial agent, as needed, as long as the electromagnetic wave absorbing effect is not impaired.
  • the electromagnetic wave absorptive composition of this invention can be obtained by mixing and stirring a tin coating material with a resin composition.
  • the electromagnetic wave absorber of the present invention has a structure in which an electromagnetic wave absorbing layer composed of the above-mentioned electromagnetic wave absorbing composition and an electromagnetic wave reflecting layer are laminated.
  • the electromagnetic wave absorber of the present invention has, for example, an electromagnetic wave absorbing layer made of an electromagnetic wave absorbing composition having a predetermined complex dielectric constant on one side of an electromagnetic wave reflecting layer such as aluminum foil according to the target frequency. And the amplitude and phase of the electromagnetic wave reflected by the surface of the electromagnetic wave absorbing layer and the electromagnetic wave reflected and returned by the interface between the laminated electromagnetic wave reflecting layer and the electromagnetic wave absorbing layer.
  • the electromagnetic wave absorbing layer can also be obtained by directly applying the electromagnetic wave absorbing composition to the electromagnetic wave reflecting layer, or bonding after curing the electromagnetic wave absorbing composition coated on a peelable protective film such as a polyethylene terephthalate film It can also be obtained by a method of affixing to an electromagnetic wave reflection layer via an agent or the like.
  • the absorption frequency may be designed in consideration of the thickness of the adhesive layer.
  • the layer forming step of the electromagnetic wave absorbing layer may be carried out using a conventionally known forming method.
  • a peelable protective film is laminated And those that cure it.
  • a coating method although a method using a bar coater, a comma coater, a die coater, etc. is mentioned, it is not limited to these
  • the electromagnetic wave reflection layer according to the present invention may be a metal plate of aluminum, copper, iron, stainless steel or the like, a metal foil, or a polymer film on which a thin film of the above metal is formed by vacuum evaporation or plating, the above metal or carbon fiber
  • the resin or the like is reinforced with a woven fabric or non-woven fabric of a conductive material such as, etc., any material that can reflect electromagnetic waves can be used.
  • the peelable protective film examples include a polypropylene film, a fluorine resin film, a polyethylene film, a polyethylene terephthalate film, paper, and a film which has been subjected to a peeling treatment with a silicone resin (a peeling treated film) and the like.
  • the thickness of the peelable protective film is not particularly limited, but is preferably 1 to 200 ⁇ m, and more preferably 10 to 50 ⁇ m.
  • the peelable protective film preferably has a peel strength of 1.0 to 50 g / cm. If it is 1.0 g / cm or less, the electromagnetic wave absorbing layer and the peelable protective film are easily peeled off during curing, and the surface of the electromagnetic wave absorbing layer tends to be uneven. When peeling away an electromagnetic wave absorption layer and a peelable protective film as it is 50 g / cm or more, there exists a possibility that a defect etc. may arise.
  • the method of curing the electromagnetic wave absorbing layer is not particularly limited as long as it can cure the electromagnetic wave absorbing layer in the sheet in which the electromagnetic wave absorbing layer and the peelable protective film are sequentially laminated on the electromagnetic wave reflecting layer, for example There is a method of heating the obtained sheet at an arbitrary temperature.
  • the heating temperature at the time of curing may be arbitrarily determined in consideration of the type of the electromagnetic wave absorbing composition and the like.
  • Example 1 Resin composition: polyurethane acrylate having a weight average molecular weight of 2,500 and a viscosity of 6,500 mPa ⁇ s / 25 ° C. (made by Arakawa Chemical Industries, Ltd.) 100 parts by mass, antimony-doped tin oxide coated mica (Merck Product name: Iriotec (trademark registration 7330) 10 parts by mass, polymerization initiator: 1,1,3,3-tetramethylbutyl-peroxy-2-ethylhexanate (trade name: Perocta O, manufactured by NOF Corporation) 1.0 parts by mass was mixed and stirred by a known method to obtain an electromagnetic wave absorbing composition of the present invention.
  • the obtained electromagnetic wave absorbing composition was coated on a 12 ⁇ m thick aluminum foil (electromagnetic wave reflecting layer) to form an electromagnetic wave absorbing layer. Furthermore, the peeling-treated surface of the peeling-treated polyethylene terephthalate film and the electromagnetic wave absorbing layer are attached to each other, heated in a hot air circulating dryer at 100 ° C. for 10 minutes, and the thickness of the electromagnetic wave absorbing layer is 330 ⁇ m.
  • the electromagnetic wave absorber of the present invention having a sheet shape is obtained.
  • Example 2 An electromagnetic wave absorbing composition and an electromagnetic wave absorber of the present invention in the same manner as in Example 1 except that the content of antimony-doped tin oxide-coated mica (product name: Iriotec (trademark registered) 7330, manufactured by Merck Ltd.) was 20 parts by mass. I got
  • Example 3 An electromagnetic wave absorbing composition and an electromagnetic wave absorber of the present invention in the same manner as in Example 1 except that the content of antimony-doped tin oxide-coated mica (product name: Iriotec (trademark registered) 7330, manufactured by Merck Ltd.) was 30 parts by mass. I got
  • Example 4 An electromagnetic wave absorbing composition and an electromagnetic wave absorber of the present invention in the same manner as in Example 1 except that the content of antimony-doped tin oxide-coated mica (product name: Iriotec (registered trademark) 7330, manufactured by Merck Ltd.) was 40 parts by mass. I got
  • Example 5 An electromagnetic wave absorbing composition and an electromagnetic wave absorber of the present invention in the same manner as in Example 1 except that the content of antimony-doped tin oxide-coated mica (product name: Iriotec (trademark registered) 7330, manufactured by Merck Ltd.) was 50 parts by mass. I got
  • Example 6 An electromagnetic wave absorbing composition and an electromagnetic wave absorber of the present invention in the same manner as in Example 1 except that the content of antimony-doped tin oxide-coated mica (product name: Iriotec (registered trademark) 7330, manufactured by Merck Ltd.) was 60 parts by mass. I got
  • Example 7 An electromagnetic wave absorber of the present invention was obtained in the same manner as in Example 3 except that the thickness of the electromagnetic wave absorption layer was set to 520 ⁇ m.
  • Example 8 An electromagnetic wave absorber of the present invention was obtained in the same manner as in Example 3 except that the thickness of the electromagnetic wave absorption layer was 780 ⁇ m.
  • Example 9 An electromagnetic wave absorber of the present invention was obtained in the same manner as in Example 3 except that the thickness of the electromagnetic wave absorption layer was set to 1100 ⁇ m.
  • Example 1 The same as Example 1, except that 75 parts by weight of carbon black (trade name: SCMG-AF) from carbon black (trade name: SCMG-AF) was used instead of antimony-doped tin oxide-coated mica (trade name: Iriotec (trade name: 7330) from Merck).
  • SCMG-AF carbon black
  • SCMG-AF antimony-doped tin oxide-coated mica
  • Comparative example 2 Conductive needle-like titanium oxide (manufactured by Ishihara Sangyo Kaisha, Ltd.) having an average diameter of 0.5 ⁇ m and an average length of 10.0 ⁇ m instead of antimony-doped tin oxide-coated mica (trade name: Iriotec (trademark registered) 7330)
  • a comparative electromagnetic wave absorbent composition and an electromagnetic wave absorber were obtained in the same manner as in Example 1 except that 20 parts by mass of -4000 were used.
  • the electromagnetic wave absorbers of Example 3 and Example 4 using antimony-doped tin oxide-coated mica have curves approximated to non-reflection curves, and have good absorption characteristics. It was a body.
  • the electromagnetic wave absorber of Comparative Example 1 using carbon black and the electromagnetic wave absorber of Comparative Example 2 using conductive needle-like titanium oxide the slope of the curve is different from the non-reflection curve, and the absorption characteristic is It was confirmed to be inferior to Example 3 and Example 4.
  • FIG. 1 the electromagnetic wave absorber of Comparative Example 1 using carbon black
  • the electromagnetic wave absorber of Comparative Example 2 using conductive needle-like titanium oxide the slope of the curve is different from the non-reflection curve, and the absorption characteristic is It was confirmed to be inferior to Example 3 and Example 4.
  • Example 3 having an antimony-doped tin oxide-coated mica content of 30 parts by mass and Example 4 having an antimony-doped tin oxide-coated mica content of 40 parts by mass exhibited a non-reflection curve.
  • the electromagnetic wave absorber has a curve close to that of the above and has good absorption characteristics.
  • the content of antimony-doped tin oxide-coated mica is 10 parts by mass
  • the content of antimony-doped tin oxide-coated mica is 20 parts by mass
  • the content of antimony-doped tin oxide-coated mica is 20 parts by mass
  • the content of antimony-doped tin oxide-coated mica is particularly preferably 30 to 40 parts by mass with respect to 100 parts by mass of the resin composition.
  • Example 3 The electromagnetic wave absorbers obtained in Example 3 and Examples 7 to 9 were peeled off from the polyethylene terephthalate film to obtain respective electromagnetic wave absorbers for evaluation.
  • the evaluation electromagnetic wave absorber was cut into a length of 150 mm ⁇ 150 mm to make a test piece, and the reflection attenuation of the electromagnetic wave in the 18 GHz to 110 GHz frequency band was measured.
  • the measurement measured the advancing direction (TD) which coated the electromagnetic wave absorptive composition on the aluminum foil (electromagnetic wave reflection layer), and the direction (MD) perpendicular
  • the electromagnetic wave absorbers obtained in Example 3 and Examples 7 to 9 have sufficient attenuation due to attenuation of -20 dB or more in both the TD and MD directions. It was confirmed to have. From this, the electromagnetic wave absorber using the antimony-doped tin oxide-coated mica has no directivity (anisotropic) in the radio wave absorption performance, and has sufficient radio wave absorption performance to electromagnetic waves from almost all directions. Further, in Example 3 and Examples 7 to 9, the content of the antimony-doped tin oxide-coated mica is the same, and the thickness of the electromagnetic wave absorbing layer is different. In FIGS.
  • the peak wavelength frequency is 20 dB to 100 GHz and the return loss is ⁇ 20 dB or more.
  • the electromagnetic wave absorbers obtained in Example 3 and Examples 7 to 9 are less dependent on frequency, and it is possible to match the frequency to a wide band of 20 GHz to 100 GHz simply by adjusting the thickness with the same prescription. I understood it.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
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  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
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Abstract

The present invention provides: an electromagnetic wave absorbing composition characterized by comprising an antimony-doped tin oxide-coated mica or an antimony-doped tin oxide-coated talc, and a resin composition; and an electromagnetic wave absorber using the electromagnetic wave absorbing composition.

Description

電磁波吸収性組成物および電磁波吸収体Electromagnetic wave absorbing composition and electromagnetic wave absorber
　本発明は、電磁波吸収性組成物および電磁波吸収体に関し、特にＧＨｚ帯域において電磁波障害を防止するための電磁波吸収性組成物および電磁波吸収体に関する。
　本願は、２０１７年１０月２４日に、日本に出願された特願２０１７－２０４９０４号に基づき優先権を主張し、その内容をここに援用する。 The present invention relates to an electromagnetic wave absorbing composition and an electromagnetic wave absorber, and more particularly to an electromagnetic wave absorbing composition and an electromagnetic wave absorber for preventing electromagnetic wave interference in a GHz band.
Priority is claimed on Japanese Patent Application No. 2017-204904, filed Oct. 24, 2017, the content of which is incorporated herein by reference.
　近年、マイクロ波からミリ波帯域（ＧＨｚ帯域）の電磁波の利用が急速に進み、自動車の衝突防止用レーダ、自動運転制御用レーダ等に広く用いられようとしている。このようなシステムが、正常に動作するためには、不要な電磁波の外部への放出や外部からの進入を効率的に抑制することが必要であり、かつ車載用として使用し得る長期耐熱安定性と、狭小箇所へも配置可能な薄型の電磁波吸収体が求められている。 In recent years, the use of electromagnetic waves in the millimeter wave band (GHz band) from microwaves has rapidly progressed, and is being widely used in radars for collision prevention of automobiles, radars for automatic driving control, and the like. In order for such a system to operate properly, it is necessary to efficiently suppress the emission of unnecessary electromagnetic waves to the outside and the approach from the outside, and long-term heat stability that can be used as a vehicle In addition, a thin electromagnetic wave absorber that can be disposed even in a narrow area is required.
　かかる目的の電磁波吸収体には、特定の周波数のみを吸収するタイプとして、所定の複素比誘電率を持った電磁波吸収層を、対象周波数に応じて所定の厚みとして、その片面に電磁波反射層を設けたいわゆる整合型電磁波吸収体と、軟磁性粉末等を使用して比較的広域の周波数帯に渡って、電磁波を吸収するタイプの電磁波吸収体が知られている。 The electromagnetic wave absorber for this purpose has an electromagnetic wave absorbing layer with a predetermined complex relative dielectric constant as a type that absorbs only a specific frequency, an electromagnetic wave reflection layer on one side with a predetermined thickness according to the target frequency. There is known an electromagnetic wave absorber of the type that absorbs electromagnetic waves over a relatively wide frequency band using so-called matched electromagnetic wave absorbers provided and soft magnetic powder or the like.
　整合型電磁波吸収体は、電磁波吸収層表面で反射する電磁波と、裏面の電磁波反射層と電磁波吸収層の界面で反射されて戻ってくる電磁波とが打ち消しあうように、それらの振幅と位相をコントロールして設計されたものが一般的である。電磁波が垂直に入射する場合において、無反射となる場合の電磁波吸収層の複素比誘電率の実部と虚部の関係は、ｄ／λ（ｄ：電磁波吸収層の厚み、λ：電磁波の波長）に応じて変化することが知られている。 The matching type electromagnetic wave absorber controls the amplitude and the phase so that the electromagnetic wave reflected on the surface of the electromagnetic wave absorption layer and the electromagnetic wave reflected and returned from the interface between the electromagnetic wave reflection layer on the back surface and the electromagnetic wave absorption layer cancel each other. Are generally designed. The relationship between the real part and the imaginary part of the complex relative permittivity of the electromagnetic wave absorption layer in the case of no reflection when the electromagnetic wave is vertically incident is d / λ (d: thickness of the electromagnetic wave absorption layer, λ: wavelength of the electromagnetic wave It is known to change according to).
　従来、整合型電磁波吸収体における電磁波吸収層には、樹脂に導電性針状酸化チタンと導電性カーボンブラックを配合した整合型ミリ波吸収シートが提案されている（例えば、特許文献１参照）。
　また、液状のエポキシ変性ウレタンゴムにカーボンブラックを配合した整合型ミリ波吸収シートが提案されている（例えば、特許文献２参照）。 Conventionally, for the electromagnetic wave absorbing layer in the matching type electromagnetic wave absorber, a matching type millimeter wave absorbing sheet in which conductive needle-like titanium oxide and conductive carbon black are blended in a resin has been proposed (see, for example, Patent Document 1).
In addition, a matched millimeter wave absorbing sheet in which carbon black is mixed with liquid epoxy modified urethane rubber has been proposed (see, for example, Patent Document 2).
特開２００２－５７４８５号公報JP 2002-57485 A 特開平４－３４０２９９号公報JP-A-4-340299
　しかしながら、特許文献１の整合型ミリ波吸収シートは、導電性針状酸化チタンを使用しているため、コーティングや延伸等のせん断力をかけてシート化すると電磁波吸収性能に異方性を生じるという問題を有していた。
　また、特許文献２の整合型ミリ波吸収シートは、カーボンブラックを含有しているため、整合させる周波数に応じてカーボンブラックの添加量と電磁波吸収層の厚みを調整する必要がある。つまり、カーボンブラックを配合した電磁波吸収層は、同一処方において誘電率虚部に周波数依存性があるため整合させる周波数に合わせて添加量を調整する必要があった。 However, since the matching type millimeter-wave absorbing sheet of Patent Document 1 uses conductive needle-like titanium oxide, it is said that electromagnetic wave absorption performance is anisotropic when it is sheeted by applying a shearing force such as coating or drawing. I had a problem.
Moreover, since the matching type | mold millimeter-wave absorption sheet of patent document 2 contains carbon black, it is necessary to adjust the addition amount of carbon black, and the thickness of an electromagnetic wave absorption layer according to the frequency to match. That is, since the electromagnetic wave absorption layer which mix | blended carbon black has frequency dependency in the dielectric constant imaginary part in the same prescription, it was necessary to adjust the addition amount according to the frequency to match.
　そこで、本発明は、電磁波吸収性能に異方性を生じないで、誘電率虚部に周波数依存性が少ないＧＨｚ帯域の電磁波を効率よく吸収することができる電磁波吸収性組成物および電磁波吸収体を提供することを目的とする。 Therefore, the present invention provides an electromagnetic wave absorbing composition and an electromagnetic wave absorber capable of efficiently absorbing an electromagnetic wave in the GHz band having little frequency dependency in the imaginary part of dielectric constant without generating anisotropy in the electromagnetic wave absorption performance. Intended to be provided.
　本発明者らは鋭意検討した結果、樹脂組成物中に、特定の微粒子を含有することによって、ＧＨｚ帯域の電磁波を効率よく吸収することができる整合型電磁波吸収体を得ることができることを見出し、本発明に至ったものである。 As a result of intensive investigations, the present inventors have found that the inclusion of specific fine particles in the resin composition makes it possible to obtain a matched electromagnetic wave absorber capable of efficiently absorbing electromagnetic waves in the GHz band. The present invention has been achieved.
　すなわち、本発明（１）は、アンチモンドープ酸化スズ被覆雲母又はアンチモンドープ酸化スズ被覆タルクと、樹脂組成物とを含有することを特徴とする電磁波吸収性組成物である。
　本発明（２）は、前記樹脂組成物が、アクリル系樹脂であって、ビニル基を有するエポキシアクリレート、ウレタンアクリレート、エステルアクリレート、ブタジエンアクリレート、シリコーンアクリレート、アミノ樹脂アクリレートから選ばれるいずれか１種を含むことを特徴とする前記発明（１）に記載の電磁波吸収性組成物である。
　本発明（３）は、前記発明（１）または前記発明（２）に記載の電磁波吸収性組成物からなる電磁波吸収層と電磁波反射層とを積層してなることを特徴とする電磁波吸収体である。 That is, the present invention (1) is an electromagnetic wave absorbing composition comprising antimony-doped tin oxide-coated mica or antimony-doped tin oxide-coated talc and a resin composition.
The present invention (2) is that the resin composition is an acrylic resin, and any one selected from an epoxy acrylate having a vinyl group, a urethane acrylate, an ester acrylate, a butadiene acrylate, a silicone acrylate, and an amino resin acrylate. It is an electromagnetic wave absorptive composition as described in the said invention (1) characterized by including.
The present invention (3) is an electromagnetic wave absorber characterized in that the electromagnetic wave absorbing layer composed of the electromagnetic wave absorbing composition according to the invention (1) or the invention (2) and an electromagnetic wave reflecting layer are laminated. is there.
　従来の厚みの薄い電磁波吸収体は、わずかな寸法変化であっても全体厚に対する変化割合が大きく、周波数の高いＧＨｚ帯域では、ピーク吸収周波数を大きく変動させてしまうという周波数依存性の問題を有していた。本発明によれば、電磁波吸収性能に異方性を生じないで、周波数依存性が少ないＧＨｚ帯域の電磁波を効率よく吸収することができる電磁波吸収性組成物および電磁波吸収体を提供することができる。 Conventional electromagnetic wave absorbers with a small thickness have a large dependence on the total thickness even with a slight dimensional change, and have a frequency dependency problem in which the peak absorption frequency fluctuates significantly in the high frequency GHz band. Was. According to the present invention, it is possible to provide an electromagnetic wave absorbing composition and an electromagnetic wave absorber capable of efficiently absorbing an electromagnetic wave in the GHz band having little frequency dependency without causing anisotropy in the electromagnetic wave absorption performance. .
実施例及び比較例における電磁波吸収体の各周波数帯における実項数と虚数項との関係を示したグラフである。It is the graph which showed the relationship of the real number and imaginary term in each frequency band of the electromagnetic wave absorber in an Example and a comparative example. 実施例１～６における電磁波吸収体の各周波数帯における実項数と虚数項との関係を示したグラフである。FIG. 16 is a graph showing the relationship between the number of real terms and the imaginary term in each frequency band of the electromagnetic wave absorbers in Examples 1 to 6. FIG. 実施例３における電磁波吸収体の反射減衰量を示したグラフである。15 is a graph showing the return loss of the electromagnetic wave absorber in Example 3. 実施例７における電磁波吸収体の反射減衰量を示したグラフである。21 is a graph showing the return loss of the electromagnetic wave absorber in Example 7. 実施例８における電磁波吸収体の反射減衰量を示したグラフである。21 is a graph showing the return loss of the electromagnetic wave absorber in Example 8. FIG. 実施例９における電磁波吸収体の反射減衰量を示したグラフである。21 is a graph showing the return loss of the electromagnetic wave absorber in Example 9.
　以下、本発明の電磁波吸収性組成物を詳細に説明する。
　本発明の電磁波吸収性組成物は、アンチモンドープ酸化スズ被覆雲母又はアンチモンドープ酸化スズ被覆タルクと、樹脂組成物とを含有する。
　樹脂組成物としては、ゴムを包含する広義の樹脂を含むものであり、その種類は特に制限されるものではなく、用途に応じた物性、例えば強度や耐熱性、成形性等を考慮して適宜選択される。例えば、クロロプレンゴム、クロロスルホン化ポリエチレンゴム、塩素化ポリエチレンゴム、エチレン・α－オレフィンゴム、エチレン・プロピレンゴム、シリコーンゴム、アクリルゴム、フッ素ゴム、スチレン・ブタジエンゴム、イソプレンゴム等のゴム類、以下に例示する熱可塑性樹脂、シリコーン樹脂、フェノール樹脂、ユリア樹脂、エポキシ樹脂等の熱硬化性樹脂、ウレタン系、アミド系、エステル系等の各種熱可塑性エラストマー等を使用することができる。また、必要に応じて、これらの２種以上を混合して使用することもできる。 Hereinafter, the electromagnetic wave absorptive composition of the present invention will be described in detail.
The electromagnetic wave absorbing composition of the present invention contains antimony-doped tin oxide-coated mica or antimony-doped tin oxide-coated talc, and a resin composition.
The resin composition includes a resin in a broad sense including rubber, and the kind thereof is not particularly limited, and in view of physical properties according to the application, for example, strength, heat resistance, moldability and the like, as appropriate It is selected. For example, chloroprene rubber, chlorosulfonated polyethylene rubber, chlorinated polyethylene rubber, ethylene / α-olefin rubber, ethylene / propylene rubber, silicone rubber, acrylic rubber, fluororubber, styrene / butadiene rubber, rubber such as isoprene rubber, etc. Thermoplastic resins, silicone resins, phenol resins, urea resins, thermosetting resins such as epoxy resins, and various thermoplastic elastomers such as urethane resins, amide resins and ester resins can be used. Moreover, these 2 or more types can also be mixed and used as needed.
　熱可塑性樹脂としては、例えば、ポリオレフィン系樹脂（例えば、ポリエチレン、ポリプロピレン、エチレン・酢酸ビニル共重合体等）、塩化ビニル樹脂、ポリスチレン系樹脂（ポリスチレン、アクリロニトリル・スチレン共重合体、メタクリル酸メチル・スチレン共重合体、アクリロニトリル・ブタジエン・スチレン共重合体等）、アクリル系樹脂、酢酸ビニル系樹脂、シリコーン系樹脂、フッ素系樹脂、ポリエステル系樹脂、ポリアミド系樹脂、ポリカーボネート樹脂等が挙げられる。 Examples of the thermoplastic resin include polyolefin resins (eg, polyethylene, polypropylene, ethylene / vinyl acetate copolymer, etc.), vinyl chloride resin, polystyrene resins (polystyrene, acrylonitrile / styrene copolymer, methyl methacrylate / styrene) Copolymers, acrylonitrile-butadiene-styrene copolymers, etc.), acrylic resins, vinyl acetate resins, silicone resins, fluorine resins, polyester resins, polyamide resins, polycarbonate resins, etc. may be mentioned.
　この中でもアクリル系樹脂が好ましい。アクリル系樹脂としては、ビニル基を有するエポキシアクリレート、ウレタンアクリレート、エステルアクリレート、ブタジエンアクリレート、シリコーンアクリレート、アミノ樹脂アクリレートを用いることが好ましく、より好ましくは、繰り返し単位が２～２０程度のアクリル系オリゴマーであり、末端に２～６個のビニル基を持っているエポキシアクリレート、ウレタンアクリレート、ポリエステルアクリレート、ブタジエンアクリレート、シリコーンアクリレート、及び、アミノ樹脂アクリレート等が挙げられるが、中でも３官能以下のものが樹脂の硬化収縮を抑えやすい点において好ましい。また、これらは単独または２種類以上組み合わせて用いることが可能であり、中でも重量平均分子量が５００～１００００、粘度が３０００～５０００００ｍＰａ・ｓ／２５℃のウレタンアクリレートが無溶剤系での塗工が容易行える点においてより好ましい。電磁波吸収層を形成する際に、溶剤を使用しないことで残留溶剤の揮発による電磁波吸収層の寸法変化を抑制しやすくなる。尚、重量平均分子量は、ＪＩＳ　Ｋ７２５２に準拠して、ゲルパーメーションクロマトグラフィー（日本分光株式会社製）を用いて測定される値であり、粘度はＥ型粘度計を用いて測定される値である。 Among these, acrylic resins are preferable. As the acrylic resin, epoxy acrylate having vinyl group, urethane acrylate, ester acrylate, butadiene acrylate, silicone acrylate, amino resin acrylate is preferably used, and more preferably, acrylic oligomer having about 2 to 20 repeating units. And epoxy acrylates having 2 to 6 vinyl groups at the end, urethane acrylates, polyester acrylates, butadiene acrylates, silicone acrylates, amino resin acrylates, etc., among which those having trifunctional or less resins are preferred. It is preferable at the point which is easy to suppress hardening shrinkage. In addition, these can be used alone or in combination of two or more, and among them, urethane acrylate having a weight average molecular weight of 500 to 10,000 and a viscosity of 3,000 to 500,000 mPa · s / 25 ° C can easily be applied without solvent. It is more preferable in that it can be done. When forming an electromagnetic wave absorption layer, it becomes easy to suppress the dimensional change of the electromagnetic wave absorption layer by volatilization of a residual solvent by not using a solvent. In addition, a weight average molecular weight is a value measured using gel permeation chromatography (made by JASCO Corporation) based on JISK7252, and a viscosity is a value measured using an E-type viscometer. is there.
　電磁波吸収性組成物には重合開始剤が含有されていてもよい。重合開始剤としては、公知のものを使用可能であるが、有機過酸化物が好ましい。有機過酸化物は、常温から３００℃程度の温度範囲において、無溶剤でアクリル系樹脂組成物を重合硬化させる温度を自由に設定できる点において好適である。上記有機過酸化物としては、メチルエチルケトンパーオキサイド、シクロヘキサンパーオキサイド、３，３，５－トリメチルシクロヘキサノンパーオキサイド、メチルシクロヘキサノンパーオキサイド、メチルアセトアセテートパーオキサイド、アセチルアセトンパーオキサイド、１，１－ビス（ｔ－ブチルパーオキシ）－３，３，５トリメチルヘキサン、１，１－ビス（ｔ－ブチルパーオキシ）－シクロヘキサン、２，２－ビス（ｔ－ブチルパーオキシ）オクタン、ｎ－ブチル－４，４－ビス（ｔ－ブチルパーオキシ）バレート、２，２－ビス（ｔ－ブチルパーオキシ）ブタン、ｔ－ブチルハイドロパーオキサイド、クメンハイドロパーオキサイド、ジ－イソプロピルベンゼンハイドロパーオキサイド、ｐ－メンタンハイドロパーオキサイド、２，５－ジメチルヘキサン－２，５－ジハイドロパーオキサイド、１，１，３，３－テトラメチルブチルハイドロパーオキサイド、１，１，３，３－テトラメチルブチルパーオキシ－２－エチルヘキサネート、ジ－ｔ－ブチルパーオキサイド、ｔ－ブチルクミルパーオキサイド、ジ－クミルパーオキサイド、α，α’－ビス（ｔ－ブチルパーオキシ－ｍ－イソプロピル）ベンゼン、２，５－ジメチル－２，５－ジ（ｔ－ブチルパーオキシ）ヘキサン、２，５－ジメチル－２，５－ジ（ｔ－ブチルパーオキシ）ヘキシン、アセチルパーオキサイド、イソブチルパーオキサイド、オクタノイルパーオキサイド、デカノイルパーオキサイド、ベンゾイルパーオキサイド、ラウロイルパーオキサイド、ジラウロイルパーオキサイド、３，５，５－トリメチルヘキサノイルパーオキサイド、スクシニックアシッドパーオキサイド、２，４－ジクロロベンゾイルパーオキサイド、ｍ－トルオイルパーオキサイド、ジ－イソプロピルパーオキシジカーボネート、ジ－２－エチルヘキシルパーオキシジカーボネート、ジ－ｎ－プロピルパーオキシジカーボネート、ビス－（４－ｔ－ブチルシクロヘキシル）パーオキシジカーボネート、ジ－ミリスティルパーオキシジカーボネート、ジ－２－エトキシエチルパーオキシジカーボネート、ジ－メトキシイソプロピルパーオキシジカーボネート、ジ（３－メチル－３－メトキシブチル）パーオキシジカーボネート、ジ－アリルパーオキシジカーボネート、ｔ－ブチルパーオキシアセテート、ｔ－ブチルパーオキシイソブチレート、ｔ－ブチルパーオキシピバレート、ｔ－ブチルパーオキシネオデカネート、クミルパーオキシネオデカネート、ｔ－ブチルパーオキシ－２－エチルヘキサネート、ｔ－ブチルパーオキシ－３，５，５－トリメチルヘキサネート、ｔ－ブチルパーオキシラウレート、ｔ－ブチルパーオキシベンゾエート、ジ－ｔ－ブチルパーオキシイソフタレート、２，５－ジメチル－２，５－ジ（ベンゾイルパーオキシ）ヘキサン、ｔ－ブチルパーオキシマレイン酸、ｔ－ブチルパーオキシイソプロピルカーボネート、クミルパーオキシオクテート、ｔ－ヘキシルパーオキシネオデカネート、ｔ－ヘキシルパーオキシピバレート、ｔ－ブチルパーオキシネオヘキサネート、アセチルシクロヘキシルスルフォニルパーオキサイド、ｔ－ブチルパーオキシアリルカーボネート等が挙げられ、これらは単独または２種類以上組み合わせて使用することが出来る。 The electromagnetic wave absorbing composition may contain a polymerization initiator. As a polymerization initiator, although a well-known thing can be used, an organic peroxide is preferable. The organic peroxide is preferable in that the temperature at which the acrylic resin composition can be polymerized and cured without a solvent can be freely set in a temperature range from normal temperature to about 300 ° C. Examples of the organic peroxide include methyl ethyl ketone peroxide, cyclohexane peroxide, 3,3,5-trimethylcyclohexanone peroxide, methylcyclohexanone peroxide, methylacetoacetate peroxide, acetylacetone peroxide, 1,1-bis (t- Butylperoxy) -3,3,5 trimethylhexane, 1,1-bis (t-butylperoxy) -cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl-4,4- Bis (t-butylperoxy) barate, 2,2-bis (t-butylperoxy) butane, t-butylhydroperoxide, cumene hydroperoxide, di-isopropylbenzene hydroperoxide, p-menthane hydroperoxade I 2,5-Dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-Tetramethylbutyl hydroperoxide, 1,1,3,3-Tetramethylbutylperoxy-2-ethylhexa , Di-t-butyl peroxide, t-butylcumyl peroxide, di-cumyl peroxide, α, α'-bis (t-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2, 5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne, acetyl peroxide, isobutyl peroxide, octanoyl peroxide, decanoyl peroxide, Benzoyl peroxide, lauroyl peroxide, dilauroyl peroxide, 3,5,5-to Methyl hexanoyl peroxide, succinic acid peroxide, 2,4-dichlorobenzoyl peroxide, m-toluoyl peroxide, di-isopropylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, di-n- Propyl peroxydicarbonate, bis- (4-t-butylcyclohexyl) peroxydicarbonate, di-myristyl peroxydicarbonate, di-2-ethoxyethylperoxydicarbonate, di-methoxyisopropylperoxydicarbonate, Di (3-methyl-3-methoxybutyl) peroxydicarbonate, di-allylperoxydicarbonate, t-butylperoxyacetate, t-butylperoxyisobutyrate, t-butylperoxy Barato, t-butyl peroxy neodecanate, cumyl peroxy neodecanate, t-butyl peroxy-2-ethylhexanate, t-butyl peroxy-3,5,5-trimethylhexanate, t-butyl peroxy Oxylaurate, t-butylperoxybenzoate, di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butyl Peroxyisopropyl carbonate, cumyl peroxy octoate, t-hexyl peroxy neodecanate, t-hexyl peroxy pivalate, t-butyl peroxy neohexanate, acetyl cyclohexyl sulfonyl peroxide, t-butyl peroxy allyl carbonate Etc. These can be used alone or in combination of two or more.
　電磁波吸収性組成物における樹脂組成物／重合開始剤で表される質量比は、１０～２０００であることが好ましく、２０～１０００であることがより好ましく、３３～２００であることがさらに好ましい。質量比が、２０００を超える比率であると、硬化反応が不十分となり、長期に渡って高温状態におかれた場合、残留未硬化成分の重量減少により、電磁波吸収性組成物に収縮が生じ、電磁波吸収性能が所望の周波数帯からズレを生ずる恐れがある。また、１０未満であると、電磁波吸収性組成物の硬化収縮率が大きくなり電磁波吸収体を生産する際に層厚の制御が難しくなる恐れがある。また、最も理想的な電磁波吸収性能を得るための電磁波吸収性組成物における樹脂組成物と重合開始剤との含有量は、吸収目的の電磁波の周波数とこれに応じた複素比誘電率により任意に決定すればよい。 The mass ratio represented by the resin composition / polymerization initiator in the electromagnetic wave absorbing composition is preferably 10 to 2000, more preferably 20 to 1000, and still more preferably 33 to 200. If the mass ratio is more than 2000, the curing reaction becomes insufficient, and when left at a high temperature for a long time, the weight reduction of the remaining uncured component causes shrinkage of the electromagnetic wave absorbing composition, The electromagnetic wave absorption performance may deviate from a desired frequency band. When the ratio is less than 10, the curing shrinkage of the electromagnetic wave absorbing composition may be increased, which may make it difficult to control the layer thickness when producing an electromagnetic wave absorber. In addition, the content of the resin composition and the polymerization initiator in the electromagnetic wave absorbing composition for obtaining the most ideal electromagnetic wave absorbing performance can be arbitrarily determined by the frequency of the electromagnetic wave for absorption and the complex relative dielectric constant corresponding thereto. You should decide.
　本発明の電磁波吸収性組成物は、アンチモンドープ酸化スズ被覆雲母又はアンチモンドープ酸化スズ被覆タルクを含有する（以下、アンチモンドープ酸化スズ被覆雲母とアンチモンドープ酸化スズ被覆タルクを総称してスズ被覆物という）。
　アンチモンドープ酸化スズ被覆雲母は、例えば、雲母粉末が懸濁した水溶液中に塩化錫の塩酸水溶液とアルカリ水溶液とを同時に添加し、加水分解により錫水和物を析出被覆させ、つづいてこの溶液中に塩化錫塩化アンチモンの混合塩酸水溶液とアルカリ水溶液とを同時に添加し、前記錫水和物で被覆された雲母粉末上に共沈したアンチモン水和物を含む錫水和物を加熱焼成し、酸化アンチモンドープ酸化錫層を形成することにより得ることができる。
　また、アンチモンドープ酸化スズ被覆タルクについては、上記アンチモンドープ酸化スズ被覆雲母の製造例において、雲母粉末の代わりにタルク粉末を使用することによりタルク粉末の表面に酸化アンチモンドープ酸化錫層を形成することにより得ることができる。
　本発明におけるスズ被覆物は、雲母及びタルクの形状が扁平状であるので、従来用いられていた導電性針状酸化チタンに比べて電磁波吸収性能に異方性を生じることが少ない。 The electromagnetic wave absorbing composition of the present invention contains antimony-doped tin oxide-coated mica or antimony-doped tin oxide-coated talc (hereinafter, antimony-doped tin oxide-coated mica and antimony-doped tin oxide-coated talc are generically called tin-coated articles ).
In the antimony-doped tin oxide-coated mica, for example, a hydrochloric acid aqueous solution of tin chloride and an alkaline aqueous solution are simultaneously added to an aqueous solution in which mica powder is suspended, and tin hydrate is deposited by hydrolysis and subsequently coated in this solution Simultaneously add a mixed aqueous solution of antimony chloride and antimony chloride and an aqueous alkali solution, and heat and calcinate tin hydrate containing antimony hydrate coprecipitated on the tin hydrate-coated mica powder to oxidize It can be obtained by forming an antimony-doped tin oxide layer.
In addition, with respect to antimony-doped tin oxide-coated talc, in the above production example of antimony-doped tin oxide-coated mica, an antimony oxide-doped tin oxide layer is formed on the surface of talc powder by using talc powder instead of mica powder. It can be obtained by
Since the tin coating in the present invention has a flat shape of mica and talc, it is less likely to cause anisotropy in the electromagnetic wave absorption performance as compared with the conductive needle-like titanium oxide conventionally used.
　電磁波吸収性組成物には、少なくともアンチモンドープ酸化スズ被覆雲母又はアンチモンドープ酸化スズ被覆タルクの一方が含有されていればよい。すなわち、電磁波吸収性組成物にアンチモンドープ酸化スズ被覆雲母のみ含有させてもよいし、アンチモンドープ酸化スズ被覆タルクのみ含有させてもよいし、アンチモンドープ酸化スズ被覆雲母とアンチモンドープ酸化スズ被覆タルクの両者が含有されていてもよい。
　アンチモンドープ酸化スズ被覆雲母とアンチモンドープ酸化スズ被覆タルクの両者を電磁波吸収性組成物に含有させる場合は、アンチモンドープ酸化スズ被覆雲母とアンチモンドープ酸化スズ被覆タルクとの合計量中、アンチモンドープ酸化スズ被覆雲母が１５～４０質量％であることが好ましい。
　このようなアンチモンドープ酸化スズ被覆雲母又はアンチモンドープ酸化スズ被覆タルクとしては、メルク社製の商品名：Ｉｒｉｏｔｅｃ（商標登録）７３１０、Ｉｒｉｏｔｅｃ（商標登録）７３１５、Ｉｒｉｏｔｅｃ（商標登録）７３２０、Ｉｒｉｏｔｅｃ（商標登録）７３２５、Ｉｒｉｏｔｅｃ（商標登録）７３３０、Ｉｒｉｏｔｅｃ（商標登録）７３４０等が市販されている。 The electromagnetic wave absorbing composition may contain at least one of antimony-doped tin oxide-coated mica and antimony-doped tin oxide-coated talc. That is, the electromagnetic wave absorbing composition may contain only antimony-doped tin oxide-coated mica, or may contain only antimony-doped tin oxide-coated talc, or antimony-doped tin oxide-coated mica and antimony-doped tin oxide-coated talc Both may be contained.
When the antimony-doped tin oxide-coated mica and the antimony-doped tin oxide-coated talc are both contained in the electromagnetic wave absorbing composition, the antimony-doped tin oxide is contained in the total amount of the antimony-doped tin oxide-coated mica and the antimony-doped tin oxide-coated talc The coated mica content is preferably 15 to 40% by mass.
As such antimony-doped tin oxide-coated mica or antimony-doped tin oxide-coated talc, trade names of Iriotec (registered trademark) 7310, Iriotec (registered trademark) 7315, Iriotec (registered trademark) 7320, Iriotec (trademark) manufactured by Merck & Co. Registered 7325, Iriotec (registered trademark) 7330, Iriotec (registered trademark) 7340 and the like are commercially available.
　電磁波吸収性組成物におけるスズ被覆物の含有量は、樹脂組成物１００質量部に対して１０～６０質量部が好ましく、更に３０～４０質量部が好ましい。１０質量部未満であると十分な電磁波吸収性能を得ることがむずかしく、６０質量部より多い場合はこれもまた十分な電磁波吸収性能を得ることがむずかしい。 The content of the tin coating in the electromagnetic wave absorbing composition is preferably 10 to 60 parts by mass, more preferably 30 to 40 parts by mass with respect to 100 parts by mass of the resin composition. If it is less than 10 parts by mass, it is difficult to obtain sufficient electromagnetic wave absorption performance, and if it is more than 60 parts by mass, it is also difficult to obtain sufficient electromagnetic wave absorption performance.
　電磁波吸収性組成物には、電磁波吸収効果を損なわない範囲で、必要に応じて、難燃剤、難燃助剤、充填剤、離型剤、表面処理剤、粘度調節剤、可塑剤、抗菌剤、防黴剤、レベリング剤、消泡剤、着色剤、安定剤、カップリング剤、分散剤、滑剤、酸化防止材、紫外線吸収剤、光安定剤、帯電防止剤、反応性希釈剤等の任意成分を含有してもよい。
　本発明の電磁波吸収性組成物は、樹脂組成物にスズ被覆物を混合・攪拌して得ることができる。 In the electromagnetic wave absorbing composition, a flame retardant, a flame retardant auxiliary, a filler, a releasing agent, a surface treating agent, a viscosity controlling agent, a plasticizer, an antibacterial agent, as needed, as long as the electromagnetic wave absorbing effect is not impaired. , Antifungal agents, leveling agents, antifoaming agents, colorants, stabilizers, coupling agents, dispersants, lubricants, antioxidants, UV absorbers, light stabilizers, antistatic agents, reactive diluents, etc. You may contain an ingredient.
The electromagnetic wave absorptive composition of this invention can be obtained by mixing and stirring a tin coating material with a resin composition.
　次に、本発明の電磁波吸収体を詳細に説明する。
　本発明の電磁波吸収体は、前記の電磁波吸収性組成物からなる電磁波吸収層と電磁波反射層とを積層した構造を有する。
　本発明の電磁波吸収体は、例えば、アルミ箔等の電磁波反射層の片面に、所定の複素比誘電率を持った電磁波吸収性組成物からなる電磁波吸収層を、対象周波数に応じて所定の厚みに設けたものであり、該電磁波吸収層表面で反射した電磁波と、積層された電磁波反射層と電磁波吸収層との界面で反射されて戻ってくる電磁波とが打ち消しあうよう、それらの振幅と位相をコントロールして設計されたものである。電磁波が垂直に入射する場合において、無反射となる場合の樹脂組成物層（電磁波吸収層）の複素比誘電率の実部と虚部の関係は、ｄ／λ（ｄ：樹脂組成物層の厚み、λ：電磁波の波長）に応じて変化し、図１に示す無反射曲線で表される。 Next, the electromagnetic wave absorber of the present invention will be described in detail.
The electromagnetic wave absorber of the present invention has a structure in which an electromagnetic wave absorbing layer composed of the above-mentioned electromagnetic wave absorbing composition and an electromagnetic wave reflecting layer are laminated.
The electromagnetic wave absorber of the present invention has, for example, an electromagnetic wave absorbing layer made of an electromagnetic wave absorbing composition having a predetermined complex dielectric constant on one side of an electromagnetic wave reflecting layer such as aluminum foil according to the target frequency. And the amplitude and phase of the electromagnetic wave reflected by the surface of the electromagnetic wave absorbing layer and the electromagnetic wave reflected and returned by the interface between the laminated electromagnetic wave reflecting layer and the electromagnetic wave absorbing layer. Was designed to control the The relationship between the real part and imaginary part of the complex relative dielectric constant of the resin composition layer (electromagnetic wave absorption layer) in the case of non-reflection when electromagnetic waves are vertically incident is d / λ (d: of the resin composition layer It changes according to thickness, λ: wavelength of electromagnetic wave, and is represented by a non-reflection curve shown in FIG.
　電磁波吸収層は、電磁波反射層に電磁波吸収性組成物を直接塗工することにより得ることもできるし、ポリエチレンテレフタレートフィルム等の剥離性保護フィルムに塗工した電磁波吸収性組成物を硬化後、接着剤等を介して電磁波反射層に貼り付ける方法等によって得ることもできる。接着剤等により電磁波吸収層と電磁波反射層とを接着する場合には、接着剤層の厚みを考慮して吸収周波数設計をすればよい。
　電磁波吸収層の層形成工程は、従来公知の形成方法を用いて実施すればよく、例えば、電磁波反射層となるシートに、塗料を任意の厚さで塗工後、剥離性保護フィルムを積層し、これを硬化するものが挙げられる。塗工方法としては、バーコーター、コンマコーター、ダイコーター等を用いた方法が挙げられるが、これらに限定されるものではない The electromagnetic wave absorbing layer can also be obtained by directly applying the electromagnetic wave absorbing composition to the electromagnetic wave reflecting layer, or bonding after curing the electromagnetic wave absorbing composition coated on a peelable protective film such as a polyethylene terephthalate film It can also be obtained by a method of affixing to an electromagnetic wave reflection layer via an agent or the like. When the electromagnetic wave absorbing layer and the electromagnetic wave reflecting layer are bonded to each other by an adhesive or the like, the absorption frequency may be designed in consideration of the thickness of the adhesive layer.
The layer forming step of the electromagnetic wave absorbing layer may be carried out using a conventionally known forming method. For example, after applying a paint to a sheet to be an electromagnetic wave reflecting layer with an arbitrary thickness, a peelable protective film is laminated And those that cure it. As a coating method, although a method using a bar coater, a comma coater, a die coater, etc. is mentioned, it is not limited to these
　本発明にかかる電磁波反射層としては、アルミニウム、銅、鉄やステンレス等の金属板、金属箔や、高分子フィルムに真空蒸着やめっき等で上記金属の薄膜を形成したもの、上記金属や炭素繊維等の導電材の織布や不織布で樹脂等を補強したものなどの他、電磁波を反射可能な材料であれば上記以外のものであっても用いることができる。 The electromagnetic wave reflection layer according to the present invention may be a metal plate of aluminum, copper, iron, stainless steel or the like, a metal foil, or a polymer film on which a thin film of the above metal is formed by vacuum evaporation or plating, the above metal or carbon fiber In addition to those in which the resin or the like is reinforced with a woven fabric or non-woven fabric of a conductive material such as, etc., any material that can reflect electromagnetic waves can be used.
　前記剥離性保護フィルムとしては、ポリプロピレンフィルム、フッ素樹脂系フィルム、ポリエチレンフィルム、ポリエチレンテレフタレートフィルム、紙及びこれらにシリコーン樹脂で剥離処理を施したもの（剥離処理フィルム）等が挙げられる。剥離性保護フィルムの厚さは、特に限定されないが、１～２００μｍが好ましく、１０～５０μｍがより好ましい。 Examples of the peelable protective film include a polypropylene film, a fluorine resin film, a polyethylene film, a polyethylene terephthalate film, paper, and a film which has been subjected to a peeling treatment with a silicone resin (a peeling treated film) and the like. The thickness of the peelable protective film is not particularly limited, but is preferably 1 to 200 μm, and more preferably 10 to 50 μm.
　剥離性保護フィルムは、ピール強度が１．０～５０ｇ／ｃｍが好ましい。１．０ｇ／ｃｍ以下であると、電磁波吸収層と剥離性保護フィルムとが硬化途中で剥離し易く、電磁波吸収層の表面が不均一になり易い。５０ｇ／ｃｍ以上であると、電磁波吸収層と剥離性保護フィルムを剥離する際に、欠損等が生じる恐れがある。 The peelable protective film preferably has a peel strength of 1.0 to 50 g / cm. If it is 1.0 g / cm or less, the electromagnetic wave absorbing layer and the peelable protective film are easily peeled off during curing, and the surface of the electromagnetic wave absorbing layer tends to be uneven. When peeling away an electromagnetic wave absorption layer and a peelable protective film as it is 50 g / cm or more, there exists a possibility that a defect etc. may arise.
　電磁波吸収層の硬化方法は、例えば電磁波反射層上に、電磁波吸収層、剥離性保護フィルムが順次積層されたシート中の電磁波吸収層を硬化できえるものであれば特に限定されず、例えば、積層されたシートを任意の温度で加熱する方法が挙げられる。硬化時における加熱温度は、電磁波吸収性組成物の種類等を勘案して任意に決定すればよい。 The method of curing the electromagnetic wave absorbing layer is not particularly limited as long as it can cure the electromagnetic wave absorbing layer in the sheet in which the electromagnetic wave absorbing layer and the peelable protective film are sequentially laminated on the electromagnetic wave reflecting layer, for example There is a method of heating the obtained sheet at an arbitrary temperature. The heating temperature at the time of curing may be arbitrarily determined in consideration of the type of the electromagnetic wave absorbing composition and the like.
　次に実施例、比較例を用いて本発明をより詳細に説明するが、本発明はこれらの具体例になんら限定されるものではない。 Next, the present invention will be described in more detail using Examples and Comparative Examples, but the present invention is not limited to these specific examples.
（実施例１）
　樹脂組成物：重量平均分子量２，５００、粘度６，５００ｍＰａ・ｓ／２５℃のポリウレタンアクリレート（荒川化学工業社製　商品名：ビームセット５０５Ａ－６）１００質量部、アンチモンドープ酸化スズ被覆雲母（メルク社製　商品名：Ｉｒｉｏｔｅｃ（商標登録）７３３０）１０質量部、重合開始剤：１，１，３，３－テトラメチルブチル－パーオキシ－２－エチルヘキサネート（日油社製　商品名：パーオクタＯ）１．０質量部を混合し、公知の方法で攪拌して、本発明の電磁波吸収性組成物を得た。 Example 1
Resin composition: polyurethane acrylate having a weight average molecular weight of 2,500 and a viscosity of 6,500 mPa · s / 25 ° C. (made by Arakawa Chemical Industries, Ltd.) 100 parts by mass, antimony-doped tin oxide coated mica (Merck Product name: Iriotec (trademark registration 7330) 10 parts by mass, polymerization initiator: 1,1,3,3-tetramethylbutyl-peroxy-2-ethylhexanate (trade name: Perocta O, manufactured by NOF Corporation) 1.0 parts by mass was mixed and stirred by a known method to obtain an electromagnetic wave absorbing composition of the present invention.
　得られた電磁波吸収性組成物を、厚さ１２μｍのアルミ箔（電磁波反射層）に塗工して、電磁波吸収層を形成した。さらに、剥離処理したポリエチレンテレフタレートフィルムの剥離処理面と電磁波吸収層とを貼り合わせ、熱風循環型乾燥機中にて１００℃、１０分間の条件で加熱して、電磁波吸収層の厚さが３３０μｍのシート形状をなす本発明の電磁波吸収体を得た。 The obtained electromagnetic wave absorbing composition was coated on a 12 μm thick aluminum foil (electromagnetic wave reflecting layer) to form an electromagnetic wave absorbing layer. Furthermore, the peeling-treated surface of the peeling-treated polyethylene terephthalate film and the electromagnetic wave absorbing layer are attached to each other, heated in a hot air circulating dryer at 100 ° C. for 10 minutes, and the thickness of the electromagnetic wave absorbing layer is 330 μm The electromagnetic wave absorber of the present invention having a sheet shape is obtained.
（実施例２）
　アンチモンドープ酸化スズ被覆雲母（メルク社製　商品名：Ｉｒｉｏｔｅｃ（商標登録）７３３０）の含有量を２０質量部とした以外は実施例１と同様にして本発明の電磁波吸収性組成物及び電磁波吸収体を得た。 (Example 2)
An electromagnetic wave absorbing composition and an electromagnetic wave absorber of the present invention in the same manner as in Example 1 except that the content of antimony-doped tin oxide-coated mica (product name: Iriotec (trademark registered) 7330, manufactured by Merck Ltd.) was 20 parts by mass. I got
（実施例３）
　アンチモンドープ酸化スズ被覆雲母（メルク社製　商品名：Ｉｒｉｏｔｅｃ（商標登録）７３３０）の含有量を３０質量部とした以外は実施例１と同様にして本発明の電磁波吸収性組成物及び電磁波吸収体を得た。 (Example 3)
An electromagnetic wave absorbing composition and an electromagnetic wave absorber of the present invention in the same manner as in Example 1 except that the content of antimony-doped tin oxide-coated mica (product name: Iriotec (trademark registered) 7330, manufactured by Merck Ltd.) was 30 parts by mass. I got
（実施例４）
　アンチモンドープ酸化スズ被覆雲母（メルク社製　商品名：Ｉｒｉｏｔｅｃ（商標登録）７３３０）の含有量を４０質量部とした以外は実施例１と同様にして本発明の電磁波吸収性組成物及び電磁波吸収体を得た。 (Example 4)
An electromagnetic wave absorbing composition and an electromagnetic wave absorber of the present invention in the same manner as in Example 1 except that the content of antimony-doped tin oxide-coated mica (product name: Iriotec (registered trademark) 7330, manufactured by Merck Ltd.) was 40 parts by mass. I got
（実施例５）
　アンチモンドープ酸化スズ被覆雲母（メルク社製　商品名：Ｉｒｉｏｔｅｃ（商標登録）７３３０）の含有量を５０質量部とした以外は実施例１と同様にして本発明の電磁波吸収性組成物及び電磁波吸収体を得た。 (Example 5)
An electromagnetic wave absorbing composition and an electromagnetic wave absorber of the present invention in the same manner as in Example 1 except that the content of antimony-doped tin oxide-coated mica (product name: Iriotec (trademark registered) 7330, manufactured by Merck Ltd.) was 50 parts by mass. I got
（実施例６）
　アンチモンドープ酸化スズ被覆雲母（メルク社製　商品名：Ｉｒｉｏｔｅｃ（商標登録）７３３０）の含有量を６０質量部とした以外は実施例１と同様にして本発明の電磁波吸収性組成物及び電磁波吸収体を得た。 (Example 6)
An electromagnetic wave absorbing composition and an electromagnetic wave absorber of the present invention in the same manner as in Example 1 except that the content of antimony-doped tin oxide-coated mica (product name: Iriotec (registered trademark) 7330, manufactured by Merck Ltd.) was 60 parts by mass. I got
（実施例７）
　電磁波吸収層の厚さを５２０μｍとした以外は実施例３と同様にして本発明の電磁波吸収体を得た。 (Example 7)
An electromagnetic wave absorber of the present invention was obtained in the same manner as in Example 3 except that the thickness of the electromagnetic wave absorption layer was set to 520 μm.
（実施例８）
　電磁波吸収層の厚さを７８０μｍとした以外は実施例３と同様にして本発明の電磁波吸収体を得た。 (Example 8)
An electromagnetic wave absorber of the present invention was obtained in the same manner as in Example 3 except that the thickness of the electromagnetic wave absorption layer was 780 μm.
（実施例９）
　電磁波吸収層の厚さを１１００μｍとした以外は実施例３と同様にして本発明の電磁波吸収体を得た。 (Example 9)
An electromagnetic wave absorber of the present invention was obtained in the same manner as in Example 3 except that the thickness of the electromagnetic wave absorption layer was set to 1100 μm.
（比較例１）
　アンチモンドープ酸化スズ被覆雲母（メルク社製　商品名：Ｉｒｉｏｔｅｃ（商標登録）７３３０）の代わりにカーボンブラック（昭和電工社製　商品名：ＳＣＭＧ－ＡＦ）７５質量部とした以外は実施例１と同様にして比較用の電磁波吸収性組成物及び電磁波吸収体を得た。 (Comparative example 1)
The same as Example 1, except that 75 parts by weight of carbon black (trade name: SCMG-AF) from carbon black (trade name: SCMG-AF) was used instead of antimony-doped tin oxide-coated mica (trade name: Iriotec (trade name: 7330) from Merck). Thus, an electromagnetic wave absorbing composition and an electromagnetic wave absorber for comparison were obtained.
（比較例２）
　アンチモンドープ酸化スズ被覆雲母（メルク社製　商品名：Ｉｒｉｏｔｅｃ（商標登録）７３３０）の代わりに平均径０．５μｍ、平均長１０．０μｍの導電性針状酸化チタン（石原産業社製　商品名：ＦＴ－４０００）２０質量部とした以外は実施例１と同様にして比較用の電磁波吸収性組成物及び電磁波吸収体を得た。 (Comparative example 2)
Conductive needle-like titanium oxide (manufactured by Ishihara Sangyo Kaisha, Ltd.) having an average diameter of 0.5 μm and an average length of 10.0 μm instead of antimony-doped tin oxide-coated mica (trade name: Iriotec (trademark registered) 7330) A comparative electromagnetic wave absorbent composition and an electromagnetic wave absorber were obtained in the same manner as in Example 1 except that 20 parts by mass of -4000 were used.
（評価）＜複素比誘電率＞
　実施例１～６及び比較例１～２で得た電磁波吸収体をポリエチレンテレフタレートフィルムから剥離して、各々の評価用電磁波吸収体を得た。次に、評価用電磁波吸収体を１５０ｍｍ長×１５０ｍｍ幅に断裁して、試験片とし、それぞれの試験片について、関東電子応用開発社製の「フリースペース型Ｓパラメータ測定装置」を用い、試験片を透過する２４ＧＨｚ～７９ＧＨｚ周波数帯域における電磁波をキーサイトテクノロジー社製の「ＰＮＡネットワークアナライザーＮ５２２５Ａ」で測定することにより、実施例及び比較例の電磁波吸収層の複素比誘電率を算出した。その評価結果を表１に示した。また、表１の各周波数帯における実項数（ε’）と虚数項（ε’’）との関係を図１及び図２にグラフ化した。複素比誘電率の実項数（ε’）と虚数項（ε’’）との関係が無反射曲線に近い電磁波吸収体ほど、吸収特性が良好な電磁波吸収体といえる。 (Evaluation) <complex relative permittivity>
The electromagnetic wave absorbers obtained in Examples 1 to 6 and Comparative Examples 1 and 2 were peeled off from the polyethylene terephthalate film to obtain respective electromagnetic wave absorbers for evaluation. Next, the electromagnetic wave absorbers for evaluation are cut into 150 mm long × 150 mm wide and used as test pieces, and each of the test pieces is a test piece using “Free space type S parameter measurement device” manufactured by Kanto Electronics Application Development Co. The complex specific dielectric constant of the electromagnetic wave absorbing layer of the example and the comparative example was calculated by measuring the electromagnetic wave in the 24 GHz to 79 GHz frequency band passing through with the “PNA network analyzer N5225A” manufactured by Keysight Technologies. The evaluation results are shown in Table 1. Further, the relationship between the real number (ε ′) and the imaginary term (ε ′ ′) in each frequency band of Table 1 is graphed in FIG. 1 and FIG. An electromagnetic wave absorber having a relationship between the real number (ε ′) of the complex relative dielectric constant and the imaginary term (ε ′ ′) closer to the non-reflection curve can be said to be an electromagnetic wave absorber having better absorption characteristics.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　図１から明らかなように、アンチモンドープ酸化スズ被覆雲母を用いた実施例３及び実施例４の電磁波吸収体は、無反射曲線に近似した曲線を有しており、吸収特性が良好な電磁波吸収体であった。これに対して、カーボンブラックを使用した比較例１の電磁波吸収体及び導電性針状酸化チタンを使用した比較例２の電磁波吸収体は、曲線の傾きが無反射曲線とは異なり、吸収特性が実施例３及び実施例４よりは劣ることが確認された。
　また、図２から明らかなように、アンチモンドープ酸化スズ被覆雲母の含有量が３０質量部の実施例３及びアンチモンドープ酸化スズ被覆雲母の含有量が４０質量部の実施例４は、無反射曲線に近似した曲線を有しており、吸収特性が良好な電磁波吸収体であった。これに対して、アンチモンドープ酸化スズ被覆雲母の含有量が１０質量部の実施例１、アンチモンドープ酸化スズ被覆雲母の含有量が２０質量部の実施例２、アンチモンドープ酸化スズ被覆雲母の含有量が５０質量部の実施例５及びアンチモンドープ酸化スズ被覆雲母の含有量が６０質量部の実施例６は、実施例１及び実施例２の電磁波吸収体よりも無反射曲線から離れた曲線となっていた。このことから電磁波吸収性組成物において、アンチモンドープ酸化スズ被覆雲母の含有量は、樹脂組成物１００質量部に対して３０～４０質量部が特に好ましいといえる。 As is apparent from FIG. 1, the electromagnetic wave absorbers of Example 3 and Example 4 using antimony-doped tin oxide-coated mica have curves approximated to non-reflection curves, and have good absorption characteristics. It was a body. On the other hand, in the electromagnetic wave absorber of Comparative Example 1 using carbon black and the electromagnetic wave absorber of Comparative Example 2 using conductive needle-like titanium oxide, the slope of the curve is different from the non-reflection curve, and the absorption characteristic is It was confirmed to be inferior to Example 3 and Example 4.
Moreover, as is clear from FIG. 2, Example 3 having an antimony-doped tin oxide-coated mica content of 30 parts by mass and Example 4 having an antimony-doped tin oxide-coated mica content of 40 parts by mass exhibited a non-reflection curve. The electromagnetic wave absorber has a curve close to that of the above and has good absorption characteristics. On the other hand, the content of antimony-doped tin oxide-coated mica is 10 parts by mass, the content of antimony-doped tin oxide-coated mica is 20 parts by mass, the content of antimony-doped tin oxide-coated mica is 20 parts by mass Of Example 5 with 50 parts by mass and Example 6 with 60 parts by mass of the antimony-doped tin oxide-coated mica form a curve farther from the non-reflection curve than the electromagnetic wave absorbers of Examples 1 and 2 It was From this, in the electromagnetic wave absorbing composition, the content of the antimony-doped tin oxide-coated mica is particularly preferably 30 to 40 parts by mass with respect to 100 parts by mass of the resin composition.
＜反射減衰量＞
　実施例３及び実施例７～９で得た電磁波吸収体をポリエチレンテレフタレートフィルムから剥離して、各々の評価用電磁波吸収体を得た。次に、評価用電磁波吸収体を１５０ｍｍ長×１５０ｍｍ幅に断裁して、試験片とし、１８ＧＨｚ～１１０ＧＨｚ周波数帯域における電磁波の反射減衰量を測定した。測定は、電磁波吸収性組成物をアルミ箔（電磁波反射層）に塗工した進行方向（ＴＤ）と、該進行方向と垂直な方向（ＭＤ）とを測定した。測定には、関東電子応用開発社製の「フリースペース型Ｓパラメータ測定装置」を用い、キーサイトテクノロジー社製の「ＰＮＡネットワークアナライザーＮ５２２５Ａ」で測定した。
　その評価結果を表２に示した。また、反射減衰量のグラフを図３～図６に示した。 <Return loss>
The electromagnetic wave absorbers obtained in Example 3 and Examples 7 to 9 were peeled off from the polyethylene terephthalate film to obtain respective electromagnetic wave absorbers for evaluation. Next, the evaluation electromagnetic wave absorber was cut into a length of 150 mm × 150 mm to make a test piece, and the reflection attenuation of the electromagnetic wave in the 18 GHz to 110 GHz frequency band was measured. The measurement measured the advancing direction (TD) which coated the electromagnetic wave absorptive composition on the aluminum foil (electromagnetic wave reflection layer), and the direction (MD) perpendicular | vertical to this advancing direction. The measurement was carried out using “PNA network analyzer N5225A” manufactured by Keysight Technologies Inc., using “Free space type S parameter measurement device” manufactured by Kanto Electronics Application Development Co., Ltd.
The evaluation results are shown in Table 2. Further, graphs of the return loss amount are shown in FIG. 3 to FIG.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　表２及び図３～図６から明らかなように、実施例３及び実施例７～９で得た電磁波吸収体は、ＴＤ及びＭＤ両方向共に減衰量が－２０ｄＢ以上あって十分な反射減衰量を有することが確認できた。
　このことからアンチモンドープ酸化スズ被覆雲母を用いた電磁波吸収体は、電波吸収性能に方向性（異方性）がなく、ほぼ全ての方向からの電磁波に対して十分な電波吸収性能を有する。
　また、実施例３及び実施例７～９は、アンチモンドープ酸化スズ被覆雲母の含有量が同じで、電磁波吸収層の厚さが異なる。そして、図３～図６では２０ＧＨｚ～１００ＧＨｚで反射減衰量が－２０ｄＢ以上のピーク波長周波数を有している。このことから実施例３及び実施例７～９で得た電磁波吸収体は、周波数依存性が少なく、同一処方で厚みを調整するだけで２０ＧＨｚ～１００ＧＨｚの広帯域に周波数を整合させることが可能であることがわかった。 As is apparent from Table 2 and FIGS. 3 to 6, the electromagnetic wave absorbers obtained in Example 3 and Examples 7 to 9 have sufficient attenuation due to attenuation of -20 dB or more in both the TD and MD directions. It was confirmed to have.
From this, the electromagnetic wave absorber using the antimony-doped tin oxide-coated mica has no directivity (anisotropic) in the radio wave absorption performance, and has sufficient radio wave absorption performance to electromagnetic waves from almost all directions.
Further, in Example 3 and Examples 7 to 9, the content of the antimony-doped tin oxide-coated mica is the same, and the thickness of the electromagnetic wave absorbing layer is different. In FIGS. 3 to 6, the peak wavelength frequency is 20 dB to 100 GHz and the return loss is −20 dB or more. From this, the electromagnetic wave absorbers obtained in Example 3 and Examples 7 to 9 are less dependent on frequency, and it is possible to match the frequency to a wide band of 20 GHz to 100 GHz simply by adjusting the thickness with the same prescription. I understood it.

Claims (3)

  1. 　アンチモンドープ酸化スズ被覆雲母又はアンチモンドープ酸化スズ被覆タルクと、樹脂組成物とを含有することを特徴とする電磁波吸収性組成物。 An electromagnetic wave absorbing composition comprising antimony-doped tin oxide-coated mica or antimony-doped tin oxide-coated talc and a resin composition.
  2. 　前記樹脂組成物が、アクリル系樹脂であって、ビニル基を有するエポキシアクリレート、ウレタンアクリレート、エステルアクリレート、ブタジエンアクリレート、シリコーンアクリレート、アミノ樹脂アクリレートから選ばれるいずれか１種を含むことを特徴とする請求項１に記載の電磁波吸収性組成物。 The resin composition is an acrylic resin, and contains any one selected from an epoxy acrylate having a vinyl group, a urethane acrylate, an ester acrylate, a butadiene acrylate, a silicone acrylate, and an amino resin acrylate. Item 2. The electromagnetic wave absorbing composition according to item 1.
  3. 　請求項１または請求項２に記載の電磁波吸収性組成物からなる電磁波吸収層と電磁波反射層とを積層してなることを特徴とする電磁波吸収体。 An electromagnetic wave absorber comprising an electromagnetic wave absorbing layer comprising the electromagnetic wave absorbing composition according to claim 1 and an electromagnetic wave reflecting layer laminated on one another.
PCT/JP2018/037539 2017-10-24 2018-10-09 Electromagnetic wave absorbing composition and electromagnetic wave absorber WO2019082634A1 (en)

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