JP2002118390A - Radio wave absorber - Google Patents
Radio wave absorberInfo
- Publication number
- JP2002118390A JP2002118390A JP2000310148A JP2000310148A JP2002118390A JP 2002118390 A JP2002118390 A JP 2002118390A JP 2000310148 A JP2000310148 A JP 2000310148A JP 2000310148 A JP2000310148 A JP 2000310148A JP 2002118390 A JP2002118390 A JP 2002118390A
- Authority
- JP
- Japan
- Prior art keywords
- radio wave
- wave absorber
- volume resistivity
- resin
- carbon black
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000006096 absorbing agent Substances 0.000 title claims abstract description 55
- 239000006229 carbon black Substances 0.000 claims abstract description 34
- 229920005989 resin Polymers 0.000 claims abstract description 25
- 239000011347 resin Substances 0.000 claims abstract description 25
- 238000004519 manufacturing process Methods 0.000 claims abstract description 16
- 238000000034 method Methods 0.000 claims abstract description 6
- 239000000463 material Substances 0.000 claims description 28
- 238000002156 mixing Methods 0.000 claims description 9
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 4
- 239000005977 Ethylene Substances 0.000 claims description 4
- 229920001577 copolymer Polymers 0.000 claims description 3
- 238000000465 moulding Methods 0.000 claims description 2
- 235000019241 carbon black Nutrition 0.000 description 31
- 239000000523 sample Substances 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 5
- 238000005259 measurement Methods 0.000 description 5
- 229920001971 elastomer Polymers 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000005060 rubber Substances 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 3
- 238000013329 compounding Methods 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 239000005062 Polybutadiene Substances 0.000 description 2
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 description 2
- 239000011358 absorbing material Substances 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 239000003431 cross linking reagent Substances 0.000 description 2
- 239000002270 dispersing agent Substances 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 229920002857 polybutadiene Polymers 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 1
- OEPOKWHJYJXUGD-UHFFFAOYSA-N 2-(3-phenylmethoxyphenyl)-1,3-thiazole-4-carbaldehyde Chemical compound O=CC1=CSC(C=2C=C(OCC=3C=CC=CC=3)C=CC=2)=N1 OEPOKWHJYJXUGD-UHFFFAOYSA-N 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 description 1
- 244000043261 Hevea brasiliensis Species 0.000 description 1
- 241000872198 Serjania polyphylla Species 0.000 description 1
- 229920006311 Urethane elastomer Polymers 0.000 description 1
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000000996 additive effect Effects 0.000 description 1
- 229920000180 alkyd Polymers 0.000 description 1
- 230000003712 anti-aging effect Effects 0.000 description 1
- MTAZNLWOLGHBHU-UHFFFAOYSA-N butadiene-styrene rubber Chemical compound C=CC=C.C=CC1=CC=CC=C1 MTAZNLWOLGHBHU-UHFFFAOYSA-N 0.000 description 1
- 239000012461 cellulose resin Substances 0.000 description 1
- 229920006026 co-polymeric resin Polymers 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 229920003049 isoprene rubber Polymers 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 229920003052 natural elastomer Polymers 0.000 description 1
- 229920001194 natural rubber Polymers 0.000 description 1
- 239000005011 phenolic resin Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- 229920001084 poly(chloroprene) Polymers 0.000 description 1
- 229920001643 poly(ether ketone) Polymers 0.000 description 1
- 229920006122 polyamide resin Polymers 0.000 description 1
- 229920005668 polycarbonate resin Polymers 0.000 description 1
- 239000004431 polycarbonate resin Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 229920005672 polyolefin resin Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 229920002803 thermoplastic polyurethane Polymers 0.000 description 1
Abstract
Description
【０００１】[0001]
【発明が属する技術分野】この発明は、電波吸収体に関
し、特に誘電体にカーボンを含有せしめた誘電性電波吸
収体に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave absorber, and more particularly, to a dielectric radio wave absorber in which a dielectric contains carbon.
【０００２】[0002]
【従来の技術】近年の通信技術の進展に伴い電波利用が
急増し、電波環境は悪化の一途をたどっている。この悪
化する電波環境を改善するために、種々の特性を有する
電波吸収体が開発されている。2. Description of the Related Art The use of radio waves has increased rapidly with the recent development of communication technologies, and the radio wave environment has continued to deteriorate. In order to improve the deteriorating radio wave environment, radio wave absorbers having various characteristics have been developed.
【０００３】電波吸収体には、大きく分けて、導電電流
が流れることによって電波を吸収する導電性電波吸収体
と、誘電体に誘電損失材料を混合した誘電性電波吸収体
と、磁性体をゴム等に混合した磁性電波吸収体とがあ
り、周波数帯域、入射角度、偏波、ミリ波等の特性に応
じて種々の目的に利用されている。[0003] Broadly speaking, a radio wave absorber can be roughly divided into a conductive radio wave absorber that absorbs a radio wave when a conductive current flows, a dielectric radio wave absorber in which a dielectric material is mixed with a dielectric loss material, and a magnetic material made of rubber. And the like, and are used for various purposes according to characteristics such as frequency band, incident angle, polarization, and millimeter wave.
【０００４】このうち誘電性電波吸収体は、5ＧＨｚ以
上のレーダ周波数帯用として利用されており、樹脂にカ
ーボンブラックを配合したものが一般的である（例え
ば、特開平4-340299号、特開平10−27986号など）。誘
電性電波吸収体の性能は、一般に複素比誘電率によって
評価され、比誘電率の実数部εr’と虚数部εr”との関
係が無反射条件を満足するとき、理想的な電波吸収体が
得られる。所定のカーボンブラックを用いた場合には、
複素比誘電率はカーボンブラック配合量によって決まる
と考えられ、電波吸収体の製造においては、カーボンブ
ラック配合量をゴム100重量部に対する重量部（phr）で
規定していた。[0004] Of these, dielectric wave absorbers are used for radar frequency bands of 5 GHz or more, and generally include a resin blended with carbon black (for example, JP-A-4-340299, JP-A-4-340299). No. 10-27986). The performance of a dielectric wave absorber is generally evaluated by the complex relative permittivity. When the relationship between the real part εr ′ and the imaginary part εr ″ of the relative permittivity satisfies the condition of non-reflection, the ideal wave absorber is When the predetermined carbon black is used,
It is considered that the complex relative permittivity is determined by the amount of carbon black compounded, and in the production of a radio wave absorber, the amount of carbon black compounded was specified in parts by weight (phr) with respect to 100 parts by weight of rubber.
【０００５】しかしカーボンブラック配合量を規定の量
にした場合にも必ずしも所定の複素比誘電率が得られな
い場合があった。これはカーボンブラックの分散状態が
電波特性に影響を与えるためであり、カーボンブラック
の分散状態は、混合の条件や用いるカーボンブラックの
ストラクチャーによっても異なってくる。このためカー
ボンブラック配合量を規定するのみでは、所望の電波吸
収特性を有する電波吸収体を得ることが困難であった。However, even when the compounding amount of carbon black is set to a specified amount, a predetermined complex relative permittivity may not always be obtained. This is because the dispersion state of the carbon black affects the radio wave characteristics, and the dispersion state of the carbon black varies depending on the mixing conditions and the structure of the carbon black used. For this reason, it was difficult to obtain a radio wave absorber having desired radio wave absorption characteristics only by specifying the amount of carbon black.
【０００６】また得られた電波吸収体の評価は、複素比
誘電率を測定することにより行われているが、複素比誘
電率は、導波管を用いた導波管定在波法等で測定する必
要があり、簡便な評価を行うことができなかった。この
ため製造工程において、材料が所望の特性を有するか否
かを評価し、所望の特性を有する材料を効率的に製造す
ることが困難であった。The obtained radio wave absorber is evaluated by measuring the complex relative permittivity. The complex relative permittivity is measured by a waveguide standing wave method using a waveguide. It was necessary to measure, and simple evaluation could not be performed. For this reason, in the manufacturing process, it is difficult to evaluate whether or not the material has desired properties and to efficiently manufacture a material having the desired properties.
【０００７】[0007]
【発明が解決すべき課題】そこで本発明は、カーボンブ
ラックの種類によらず所望の電波吸収特性を有する電波
吸収体を得ることを目的とする。電波特性の評価が容易
で、所望の特性を有する電波吸収体を容易に製造するこ
とができる電波吸収体の製造方法を提供することを目的
とする。Accordingly, an object of the present invention is to provide a radio wave absorber having desired radio wave absorption characteristics irrespective of the type of carbon black. It is an object of the present invention to provide a method of manufacturing a radio wave absorber, which can easily evaluate a radio wave characteristic and can easily manufacture a radio wave absorber having desired characteristics.
【０００８】[0008]
【課題を解決するための手段】上記課題を解決するため
に、本発明者らは、カーボンブラックの種類、複素比誘
電率およびその他の特性の関係について鋭意研究した結
果、カーボンブラックの種類によらず、電波吸収材料の
体積抵抗率と複素比誘電率との間によい相関があること
を見出し本発明に至ったものである。なお、導電性の電
波吸収材料については、複素比誘電率の虚数部と体積抵
抗率との間に一定の関係があることが知られているが、
誘電性電波吸収体については複素比誘電率の虚数部はそ
の電波特性の指標とはならず、虚数部と実数部との関係
が無反射条件を満たすことが必要である。本発明におい
ては、カーボンブラック分散系樹脂による誘電性電波吸
収体について複素比誘電率と体積抵抗率との相関を見出
したことにより、容易に無反射条件を満たす電波吸収体
を得ることを可能にしたものである。Means for Solving the Problems In order to solve the above problems, the present inventors have conducted intensive studies on the relationship between the type of carbon black, the complex relative permittivity, and other characteristics. Instead, the present inventors have found that there is a good correlation between the volume resistivity of the radio wave absorbing material and the complex relative permittivity, and have reached the present invention. It is known that there is a certain relationship between the imaginary part of the complex relative permittivity and the volume resistivity of the conductive electromagnetic wave absorbing material.
The imaginary part of the complex relative permittivity of the dielectric radio wave absorber does not serve as an index of the radio wave characteristic, and the relationship between the imaginary part and the real part needs to satisfy the non-reflection condition. In the present invention, it has become possible to easily obtain a radio wave absorber satisfying the non-reflection condition by finding a correlation between the complex relative permittivity and the volume resistivity of the dielectric radio wave absorber made of carbon black dispersion resin. It was done.
【０００９】すなわち、本発明の電波吸収体は、樹脂に
カーボンブラックを分散させてなる電波吸収体であっ
て、体積抵抗率が104〜107Ω・cmの範囲のものである。
体積抵抗率を上記範囲とすることにより、電波吸収体と
して適当な複素比誘電率10〜20の範囲にすることができ
る。That is, the radio wave absorber of the present invention is a radio wave absorber obtained by dispersing carbon black in a resin, and has a volume resistivity in a range of 10 4 to 10 7 Ω · cm.
By setting the volume resistivity in the above range, it is possible to make the complex specific dielectric constant suitable for a radio wave absorber in the range of 10 to 20.
【００１０】また本発明の電波吸収体の製造方法は、樹
脂に誘電損失材料を混合する工程と、誘電損失材料が混
合された樹脂の体積抵抗率を測定する工程と、前記体積
抵抗率が所定の値となるように前記誘電損失材料の混合
量を調整する工程と、所定の体積抵抗率に調整された材
料を硬化または成型する工程とを含む。The method of manufacturing a radio wave absorber according to the present invention further comprises the steps of: mixing a resin with a dielectric loss material; measuring a volume resistivity of the resin mixed with the dielectric loss material; And a step of curing or molding the material adjusted to have a predetermined volume resistivity.
【００１１】電波吸収体の製造工程において、体積抵抗
率を測定する工程を加えることにより、所定の複素比誘
電率の電波吸収体を製造することができる。また体積抵
抗率は、簡便に測定することができ、製造工程の任意の
工程で材料の電波吸収特性の評価法として採用すること
ができる。By adding a step of measuring the volume resistivity in the step of manufacturing the radio wave absorber, a radio wave absorber having a predetermined complex relative permittivity can be manufactured. Further, the volume resistivity can be easily measured, and can be adopted as an evaluation method of a radio wave absorption characteristic of a material in an arbitrary step of a manufacturing process.
【００１２】以下、本発明の電波吸収体およびその製造
方法について詳述する。本発明の電波吸収体は、樹脂に
誘電損失材料を分散させたものであり、ここで樹脂とし
ては、通常電波吸収体として用いられている公知の樹脂
を用いることができる。このような材料として、例えば
クロロプレンゴム、アクリロニトリル・ブタジエンゴ
ム、スチレン・ブタジエンゴム、天然ゴム、イソプレン
ゴム、ウレタンゴム等のゴムや、ポリオレフィン樹脂、
塩化ビニリデン樹脂、ポリアミド樹脂、ポリエーテルケ
トン樹脂、塩化ビニル樹脂、ポリエステル樹脂、アルキ
ド樹脂、フェノール樹脂、エポキシ樹脂、アクリル樹
脂、ウレタン樹脂、シリコーン樹脂、セルロース樹脂、
酢酸ビニル樹脂、エチレン・酢酸ビニル共重合体樹脂、
ポリカーボネート樹脂などの樹脂が挙げられ、これらは
必要に応じて混合して使用することができる。これら樹
脂のうち、エチレン・酢酸ビニル共重合体は成型性に優
れ、特に好適である。Hereinafter, the radio wave absorber of the present invention and the method of manufacturing the same will be described in detail. The radio wave absorber of the present invention is obtained by dispersing a dielectric loss material in a resin. As the resin, a known resin generally used as a radio wave absorber can be used. Such materials include, for example, chloroprene rubber, acrylonitrile / butadiene rubber, styrene / butadiene rubber, natural rubber, isoprene rubber, rubber such as urethane rubber, polyolefin resin,
Vinylidene chloride resin, polyamide resin, polyether ketone resin, vinyl chloride resin, polyester resin, alkyd resin, phenol resin, epoxy resin, acrylic resin, urethane resin, silicone resin, cellulose resin,
Vinyl acetate resin, ethylene / vinyl acetate copolymer resin,
Resins such as polycarbonate resins can be mentioned, and these can be mixed and used as needed. Among these resins, ethylene / vinyl acetate copolymer is excellent in moldability and is particularly suitable.
【００１３】誘電損失材料としては、カーボンブラック
が用いられる。カーボンブラックには、吸油量が大きく
比表面積の大きいストラクチャーの発達したものから、
吸油量、比表面積の小さいストラクチャー未発達のもの
まで種々あるが、そのいずれでもよく、また適宜混合し
て用いてもよい。いずれの場合にも、体積抵抗率を所定
の値とすることにより、所望の電波特性とすることがで
きる。Carbon black is used as the dielectric loss material. The carbon black has a structure with a large oil absorption and a large specific surface area.
There are a variety of structures having a small oil absorption and a small specific surface area and an undeveloped structure. Any of them may be used, or they may be appropriately mixed and used. In any case, desired radio wave characteristics can be obtained by setting the volume resistivity to a predetermined value.
【００１４】体積抵抗率は、104〜107Ω・cmの範囲とす
る。この範囲とすることにより、得られる電波吸収体の
複素比誘電率εr’(実数部)を、誘電性電波吸収体に求
められる範囲（εr＝10〜20）とすることができる。な
お、本発明において体積抵抗率は、測定温度23℃、測定
電圧5Ｖ、測定用プローブ径50mmの条件で測定した値を
意味する。The volume resistivity is in the range of 10 4 to 10 7 Ω · cm. By setting this range, the complex relative permittivity εr ′ (real part) of the obtained radio wave absorber can be set to the range (εr = 10 to 20) required for the dielectric radio wave absorber. In the present invention, the volume resistivity means a value measured under the conditions of a measuring temperature of 23 ° C., a measuring voltage of 5 V, and a measuring probe diameter of 50 mm.
【００１５】上述したように本発明の電波吸収体は、体
積抵抗率で規定されるので、損失材料の含有量は、上記
体積抵抗率となるように決められる。本発明者らの研究
によれば、高ストラクチャーのものは少量で高い損失を
示し無反射条件に達するが、添加量の変動に対する複素
比誘電率変化が大きいため製造時の物性バラツキが大き
くなる可能性があり、また低ストラクチャーのものはゴ
ムに対し比較的多量添加する必要がある。As described above, since the radio wave absorber of the present invention is defined by the volume resistivity, the content of the lossy material is determined so as to be the above volume resistivity. According to the study of the present inventors, those having a high structure show high loss with a small amount and reach non-reflection conditions, but the variation in physical properties at the time of manufacture may be large due to a large change in complex relative permittivity with respect to a change in the added amount. Those having low structure and having a low structure need to be added to rubber in a relatively large amount.
【００１６】本発明の電波吸収体は、上述した材料の
他、その体積抵抗率（すなわち複素比誘電率）に影響を
与えない範囲で、分散剤、可塑剤、架橋剤、難燃剤、老
化防止剤等の添加剤を添加してもよい。The radio wave absorber according to the present invention may further comprise a dispersing agent, a plasticizer, a cross-linking agent, a flame retardant, an antiaging agent, in addition to the above-mentioned materials, as long as the volume resistivity (ie, the complex dielectric constant) is not affected. An additive such as an agent may be added.
【００１７】本発明の電波吸収体の形態は、特に限定さ
れないが、通常シート状など所望の形状の成型体とする
か或いは塗料とする。また電波に対し反射特性を有する
シート状の材料（反射材料）上に積層し一体化してもよ
い。この場合、反射材料としては、金属板、プラスチッ
ク板上に金属の反射層を設けたもの、金属粉を含有させ
た樹脂板等が用いられる。反射材料に積層する場合、電
波吸収体の層は、一層でも複数の層で構成してもよい。
層の厚さは、次式で規定される無反射条件を満たすよう
に決定される。The form of the radio wave absorber of the present invention is not particularly limited, but is usually a molded article having a desired shape such as a sheet or a paint. Alternatively, the components may be laminated and integrated on a sheet-like material (reflective material) having a characteristic of reflecting radio waves. In this case, as the reflection material, a metal plate, a metal plate provided with a metal reflection layer on a plastic plate, a resin plate containing metal powder, or the like is used. When laminated on a reflective material, the radio wave absorber layer may be composed of one or more layers.
The thickness of the layer is determined so as to satisfy the anti-reflection condition defined by the following equation.
【００１８】[0018]
【数１】 式中、εrは複素比誘電率、λは波長を表す。(Equation 1) In the formula, εr represents a complex relative permittivity, and λ represents a wavelength.
【００１９】次に本発明の電波吸収体の製造方法につい
て説明する。まず上述した樹脂にカーボンブラックを配
合し、混合・分散する。この際、必要に応じて分散剤な
どを添加してもよい。また樹脂の種類によっては架橋剤
や加硫剤を添加する。塗料の場合には、これを所望の対
象に塗布、硬化させる。シート状物の場合には、混合物
を圧延ロールで加熱、加圧してシート状に成型する。Next, a method of manufacturing the radio wave absorber of the present invention will be described. First, carbon black is blended with the above-mentioned resin, and mixed and dispersed. At this time, a dispersant or the like may be added as necessary. Further, depending on the type of the resin, a crosslinking agent or a vulcanizing agent is added. In the case of a paint, it is applied to a desired object and cured. In the case of a sheet, the mixture is heated and pressed by a rolling roll to form a sheet.
【００２０】本発明の電波吸収体の製造方法では、この
ような製造工程の途中で或いは成型後に、体積抵抗率を
測定する工程を加える。例えば、樹脂にカーボンブラッ
クを配合、混合した後、混合物の体積抵抗率を測定す
る。体積抵抗率が所定の範囲、すなわち104〜107Ω・cm
であれば、必要に応じて所望の形状に成型する。混合物
の体積抵抗率が所定の範囲でなければ、例えばカーボン
ブラックの配合量を変えて体積抵抗率が所定の範囲とな
るように調整する。体積抵抗率を調整するには、カーボ
ンブラックの配合量を変えるほか、ストラクチャーの異
なるカーボンブラックを混合してもよい。例えば、まず
比較的少量の添加で体積抵抗率が大幅に増加する高スト
ラクチャーのカーボンブラックを添加しておき、その
後、低ストラクチャーのカーボンブラックを添加して体
積抵抗率を所定の範囲に調整することができる。このよ
うに体積抵抗率が所定範囲に調整された材料を用いて、
上述の方法により電波吸収体とする。In the method for producing a radio wave absorber of the present invention, a step of measuring the volume resistivity is added during or after such a production step. For example, after mixing and mixing carbon black with the resin, the volume resistivity of the mixture is measured. Volume resistivity is in a predetermined range, that is, 10 4 to 10 7 Ωcm
If so, it is molded into a desired shape as needed. If the volume resistivity of the mixture is not within the predetermined range, the volume resistivity is adjusted to be within the predetermined range by, for example, changing the blending amount of carbon black. In order to adjust the volume resistivity, the amount of carbon black may be changed, or carbon black having a different structure may be mixed. For example, first add a high-structure carbon black, whose volume resistivity increases significantly with a relatively small addition, and then add a low-structure carbon black to adjust the volume resistivity to a predetermined range. Can be. Using a material whose volume resistivity has been adjusted to a predetermined range in this way,
A radio wave absorber is obtained by the above method.
【００２１】或いは所定のカーボンブラックを用いた成
型品の試料を作成し、体積抵抗率を測定して、そのカー
ボンブラックについて所定の体積抵抗率となる配合量を
決定する。ついで決定された配合量で樹脂とそのカーボ
ンブラックとを混合・分散し、成型してもよい。Alternatively, a sample of a molded article using a predetermined carbon black is prepared, the volume resistivity is measured, and the amount of the carbon black to be a predetermined volume resistivity is determined. Next, the resin and its carbon black may be mixed and dispersed in the determined blending amount and molded.
【００２２】いずれの場合でも、体積抵抗率という簡便
な測定方法によって電波吸収体の特性を評価できるの
で、容易に所望の電波特性の電波吸収体を得ることがで
きる。In any case, the characteristics of the radio wave absorber can be evaluated by a simple measuring method called volume resistivity, so that the radio wave absorber having desired radio wave characteristics can be easily obtained.
【００２３】[0023]
【実施例】以下、本発明の実施例を説明する。Embodiments of the present invention will be described below.
【００２４】実施例 樹脂としてエチレン・酢酸ビニル共重合体を用い、損失
材料として表1に示すようなストラクチャーの異なる３
種類のカーボンブラックＡ、Ｂ、Ｃを用い、その配合量
を変えて電波吸収体の試料を作製した。試料は、材料を
８インチオープンロールを用いて混合した後、７０ｔon
プレスを用い150℃、5分プレスすることにより厚さ2mm
にシート成型したものである。Example 3 An ethylene / vinyl acetate copolymer was used as a resin, and three materials having different structures as shown in Table 1 were used as loss materials.
Various types of carbon blacks A, B and C were used, and the amounts of the carbon blacks were varied to prepare samples of the radio wave absorber. The sample was mixed at 70 tonnes after mixing the materials using an 8 inch open roll.
2mm thickness by pressing at 150 ° C for 5 minutes using a press
The sheet is formed into a sheet.
【００２５】[0025]
【表１】 [Table 1]
【００２６】このシート状の試料の体積抵抗率を、体積
抵抗率計（アドバンテスト社製デジタルマルチメータＴ
Ｒ6874、測定温度23℃、測定電圧5Ｖ）を用いて測定し
た。また試料を10.2mm×22.9mmの試験片に打ち抜き、方
形導波管を用い試験片端面を短絡した導波管定在波法に
より複素比誘電率を測定した。使用モードはＴＥ10モー
ドとし、測定周波数はＸ帯の中央周波数である10ＧＨｚ
とした。The volume resistivity of the sheet-shaped sample is measured by a volume resistivity meter (Digital Multimeter T by Advantest).
R6874, measurement temperature 23 ° C., measurement voltage 5 V). The sample was punched into a 10.2 mm × 22.9 mm test piece, and the complex relative permittivity was measured by a waveguide standing wave method using a rectangular waveguide with the test piece end face short-circuited. Use mode is TE10 mode, measurement frequency is 10GHz which is the center frequency of X band
And
【００２７】これら測定は一つの試料について3回行な
い、その平均を代表値とした。結果を図１および図２に
示す。図１は、複素比誘電率の実数部と配合量との関係
（a）、および虚数部と配合量との関係（ｂ）を示すグ
ラフである。図２は複素比誘電率と体積抵抗率との関係
を示すグラフである。なお、測定はカーボンの列理現象
による反射特性の異方性を確認するために列理に対し平
行および直交した２方向で行ったが、異方性は殆ど認め
られなかったため、電界と列理が直交する場合のみを示
した。These measurements were performed three times for one sample, and the average was used as a representative value. The results are shown in FIG. 1 and FIG. FIG. 1 is a graph showing the relationship (a) between the real part and the amount of complex relative permittivity, and the relationship (b) between the imaginary part and the amount of complex. FIG. 2 is a graph showing the relationship between the complex relative permittivity and the volume resistivity. The measurement was carried out in two directions parallel and perpendicular to the grain to confirm the anisotropy of the reflection characteristics due to the graining phenomenon of carbon. However, since almost no anisotropy was recognized, the electric field and grain Are orthogonal only.
【００２８】図１のグラフからわかるように、複素比誘
電率は、カーボンブラックのストラクチャーの違いによ
って配合量に対する増加の度合いが全く異なっていた。
一方、複素比誘電率はカーボンブラックの種類によらず
体積抵抗率とよい相関を示した。As can be seen from the graph of FIG. 1, the degree of increase in the complex relative permittivity with respect to the compounding amount was completely different depending on the structure of carbon black.
On the other hand, the complex relative permittivity showed a good correlation with the volume resistivity regardless of the type of carbon black.
【００２９】このことから、カーボンブラックの配合量
によって複素比誘電率を調整することは困難であるが、
体積抵抗率を所定の範囲とすることによって複素比誘電
率を精度よく調整できることがわかる。具体的には、体
積抵抗率を104〜107Ω・cmの範囲にすることにより、複
素比誘電率を10〜20の範囲に調整することができた。For this reason, it is difficult to adjust the complex relative permittivity depending on the amount of carbon black.
It can be seen that the complex relative permittivity can be accurately adjusted by setting the volume resistivity within a predetermined range. Specifically, by setting the volume resistivity in the range of 10 4 to 10 7 Ω · cm, the complex relative permittivity could be adjusted in the range of 10 to 20.
【００３０】[0030]
【発明の効果】本発明によれば、電波吸収体の特性を示
す指標として体積抵抗率を用いることにより、所望の電
波特性を有する電波吸収体を容易に製造することができ
る。According to the present invention, a radio wave absorber having desired radio wave characteristics can be easily manufactured by using the volume resistivity as an index indicating the characteristics of the radio wave absorber.
【図１】電波吸収体におけるカーボンブラック配合量と
複素比誘電率との関係を示すグラフ。FIG. 1 is a graph showing a relationship between a compounding amount of carbon black and a complex relative dielectric constant in a radio wave absorber.
【図２】電波吸収体における複素比誘電率と体積抵抗率
との関係を示すグラフ。FIG. 2 is a graph showing a relationship between a complex relative permittivity and a volume resistivity in a radio wave absorber.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 会田 二三夫 神奈川県川崎市川崎区小田栄２丁目１番１ 号 昭和電線電纜株式会社内 Ｆターム(参考） 5E321 BB32 BB60 GG05 GG11 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumio Aida 2-1-1, Sakae Oda, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture F-term in Showa Electric Wire & Cable Co., Ltd. (reference) 5E321 BB32 BB60 GG05 GG11
Claims (6)
波吸収体であって、体積抵抗率が104〜107Ω・cmである
電波吸収体。1. A radio wave absorber obtained by dispersing a dielectric loss material in a resin, wherein the radio wave absorber has a volume resistivity of 10 4 to 10 7 Ω · cm.
請求項１記載の電波吸収体。2. The radio wave absorber according to claim 1, wherein the dielectric loss material is carbon black.
であることを特徴とする請求項1または２に記載の電波
吸収体。3. The radio wave absorber according to claim 1, wherein the resin is an ethylene / vinyl acetate copolymer.
誘電損失材料が混合された樹脂の体積抵抗率を測定する
工程と、前記体積抵抗率が所定の値となるように前記誘
電損失材料の配合量を調整する工程と、所定の体積抵抗
率に調整された材料を硬化または成型する工程とを含む
電波吸収体の製造方法。4. A step of mixing a dielectric loss material with a resin;
Measuring the volume resistivity of the resin mixed with the dielectric loss material, adjusting the blending amount of the dielectric loss material such that the volume resistivity becomes a predetermined value, and adjusting the volume resistivity to a predetermined volume resistivity. Curing or molding the applied material.
・cmである請求項4記載の電波吸収体の製造方法。5. A predetermined value of the volume resistivity is 10 4 to 10 7 Ω.
5. The method for producing a radio wave absorber according to claim 4, which is cm.
からなることを特徴とする請求項４または５記載の電波
吸収体の製造方法。6. The method for manufacturing a radio wave absorber according to claim 4, wherein said dielectric loss material is made of a plurality of types of materials.
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|---|---|---|---|
| JP2000310148A JP2002118390A (en) | 2000-10-11 | 2000-10-11 | Radio wave absorber |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000310148A JP2002118390A (en) | 2000-10-11 | 2000-10-11 | Radio wave absorber |
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| Publication Number | Publication Date |
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ID=18790160
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006003924A1 (en) * | 2004-06-30 | 2006-01-12 | Denki Kagaku Kogyo Kabushiki Kaisha | Electromagnetic wave absorbent |
-
2000
- 2000-10-11 JP JP2000310148A patent/JP2002118390A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2006003924A1 (en) * | 2004-06-30 | 2006-01-12 | Denki Kagaku Kogyo Kabushiki Kaisha | Electromagnetic wave absorbent |
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