JP2006310353A - Radio wave absorber - Google Patents

Radio wave absorber Download PDF

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JP2006310353A
JP2006310353A JP2005127671A JP2005127671A JP2006310353A JP 2006310353 A JP2006310353 A JP 2006310353A JP 2005127671 A JP2005127671 A JP 2005127671A JP 2005127671 A JP2005127671 A JP 2005127671A JP 2006310353 A JP2006310353 A JP 2006310353A
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radio wave
film
wave absorber
layer
dielectric layer
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Junichi Nakanishi
純一 中西
Takashi Takayama
隆司 高山
Hidemi Ito
秀己 伊藤
Tomonori Takada
知憲 高田
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Takiron Co Ltd
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Takiron Co Ltd
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<P>PROBLEM TO BE SOLVED: To provide a durable radio wave absorber where the surface resistivity of a resistive film is nearly fixed for a long term, and initially satisfactory radio wave absorption performance can be maintained for a long term. <P>SOLUTION: In the radio wave absorber, the resistive film 3 is provided at one side of a dielectric layer 1, and a radio wave reflector 2 is provided at the opposite surface side of the dielectric layer 1. In this case, the resistive film 3 is sealed from the fresh air containing water. The contact between the resistant film 3 and the water (moisture) in the fresh air is cut off for nearly keeping stable the surface resistivity of the resistive film 3, thus preventing the radio wave absorption performance from deteriorating by a change (increase) in the surface resistivity, and hence maintaining the initially satisfactory radio wave absorption performance for a long term for extensively improving durability and reliability. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、例えば高速道路のＥＴＣ料金所などのＩＴＳ分野で電波障害や誤動作をなくすために利用される電波吸収体、特に透視性を有する電波吸収体であって、良好な電波吸収性能を長期間維持できる耐久性に優れた電波吸収体に関する。   The present invention is a radio wave absorber that is used to eliminate radio wave interference and malfunction in the ITS field such as an ETC toll gate on a highway, for example, particularly a radio wave absorber that has transparency, and has a good radio wave absorption performance. The present invention relates to a radio wave absorber excellent in durability that can be maintained for a period.

電波障害や誤動作をなくす透明な電波吸収体としては、透明なアクリル樹脂等からなる誘電体の片面に、ＩＴＯ等の金属酸化物を蒸着して抵抗薄膜を形成した透明なＰＥＴ（ポリエチレンテレフタレート）フィルム等を積層し、誘電体の反対面に光を透過する金属線格子、金属薄膜等の電波反射体を設けたものが知られている（特許文献１）。   Transparent PET (polyethylene terephthalate) film in which a resistive thin film is formed by vapor-depositing a metal oxide such as ITO on one side of a dielectric made of transparent acrylic resin, etc., as a transparent radio wave absorber that eliminates radio interference and malfunction Etc., and a radio wave reflector such as a metal wire grating or a metal thin film that transmits light on the opposite surface of the dielectric is known (Patent Document 1).

この電波吸収体は、ＩＴＯ等の金属酸化物を蒸着して抵抗薄膜を形成しているため、良好な透明性を有している。けれども、ＩＴＯ等を蒸着した抵抗薄膜は耐候性が悪く、ＩＴＯ等を蒸着するＰＥＴフィルムも耐候性が悪いため、上記の電波吸収体を屋外で使用すると、短期間の内に抵抗薄膜やＰＥＴフィルムが劣化して、透明性が著しく悪化し、黄みを帯びるという問題があった。かかる問題は、耐候性の良いフィルムを使用すると多少は改善されるが、耐候性の良いアクリル等のフィルムはＩＴＯなどの蒸着が難しいため、蒸着の容易なＰＥＴフィルムを使用せざるを得ないのが実情である。   This radio wave absorber has good transparency because a metal oxide such as ITO is deposited to form a resistive thin film. However, the resistance thin film deposited with ITO or the like has poor weather resistance, and the PET film deposited with ITO or the like has poor weather resistance. Therefore, when the above radio wave absorber is used outdoors, the resistance thin film or PET film is used within a short period of time. Deteriorated, the transparency was remarkably deteriorated, and yellowish. Such a problem is somewhat improved when a film having good weather resistance is used, but since a film such as acrylic having good weather resistance is difficult to deposit ITO or the like, it is necessary to use a PET film which is easy to deposit. Is the actual situation.

そこで、本出願人は、上記の問題を解決すべく、極細導電繊維を含んだ透明な抵抗膜と光を透過する電波反射体との間に透明な誘電体層を備え、抵抗膜の外側に透明な保護層を備えた透明電波吸収体を提案した（特願２００４−０８１９３９）。この透明電波吸収体は、極細導電繊維を含んだ抵抗膜がＩＴＯ抵抗薄膜と遜色のない良好な透明性を有し、しかも、極細導電繊維を含んだ抵抗膜の基材を自由に選択できるため、耐候性の良好な基材を選択することで、ＩＴＯ抵抗薄膜の基材に用いるＰＥＴに比べて耐候性を向上させることができ、短期間のうちに劣化して透明性の著しい低下を招く心配を解消できるものである。   Therefore, in order to solve the above problem, the present applicant has a transparent dielectric layer between a transparent resistive film containing ultrafine conductive fibers and a radio wave reflector that transmits light, and the outside of the resistive film. A transparent radio wave absorber provided with a transparent protective layer was proposed (Japanese Patent Application No. 2004-081939). In this transparent wave absorber, the resistive film containing ultrafine conductive fibers has good transparency comparable to the ITO resistive thin film, and the resistance film substrate containing ultrafine conductive fibers can be freely selected By selecting a base material having good weather resistance, the weather resistance can be improved as compared with PET used for the base material of the ITO resistance thin film, and it deteriorates within a short period of time, causing a significant decrease in transparency. It can eliminate worry.

しかしながら、この透明電波吸収体は、抵抗膜の電気抵抗（表面抵抗率）が変化するため、長期間にわたって良好な電波吸収性能を維持することが難しいという問題があり、この問題は前記特許文献１の透明電波吸収体においても見られた。その原因は明らかでないが、空気中の水分（湿気）が大きく影響しているものと推測される。
特開平５−３３５８３２号公報 However, this transparent radio wave absorber has a problem that it is difficult to maintain good radio wave absorption performance over a long period of time because the electric resistance (surface resistivity) of the resistance film changes. It was also seen in transparent wave absorbers. Although the cause is not clear, it is presumed that the moisture (humidity) in the air has a great influence.
JP-A-5-335832

本発明は上記の問題に対処するためになされたもので、抵抗膜の電気抵抗（表面抵抗率）が長期間に亘ってほぼ一定し、初期の良好な電波吸収性能を長期間に亘って維持できる、耐久性に優れた電波吸収体を提供することを、解決課題としている。   The present invention has been made to cope with the above-mentioned problems. The electric resistance (surface resistivity) of the resistance film is substantially constant over a long period of time, and the initial good radio wave absorption performance is maintained over a long period of time. An object of the present invention is to provide a radio wave absorber having excellent durability.

上記の課題を解決するため、本発明の電波吸収体は、抵抗膜を誘電体層の片面側に設けると共に、誘電体層の反対面側に電波反射体を設けた電波吸収体であって、抵抗膜を水分を含む外気から封止したことを特徴とするものである。   In order to solve the above problems, the radio wave absorber of the present invention is a radio wave absorber in which a resistive film is provided on one side of a dielectric layer and a radio wave reflector is provided on the opposite side of the dielectric layer, The resistance film is sealed from outside air containing moisture.

本発明の電波吸収体においては、抵抗膜を誘電体層とその片面側に配置された表面被覆層との間に設けて抵抗膜の周囲に封止層を形成するか、或いは、抵抗膜を誘電体層の片面に設けて抵抗膜の表面と周囲に封止層を形成するか、或いは、抵抗膜を誘電体層の片面側に配置された表面被覆層の該誘電体層との対向面に設けて抵抗膜の表面と周囲に封止層を形成することにより、抵抗膜を水分を含む外気から封止することが好ましい。   In the radio wave absorber of the present invention, a resistance film is provided between the dielectric layer and the surface coating layer disposed on one side thereof to form a sealing layer around the resistance film, or Provided on one side of the dielectric layer to form a sealing layer on and around the surface of the resistive film, or a surface coating layer disposed on one side of the dielectric layer facing the dielectric layer It is preferable to seal the resistance film from the outside air containing moisture by forming a sealing layer on and around the surface of the resistance film.

また、本発明の電波吸収体においては、抵抗膜を合成樹脂フィルムのいずれか片面に形成し、この抵抗膜形成フィルムの抵抗膜が誘電体層側となるように誘電体層の片側面側に設けると共に、抵抗膜の周囲に封止層を形成するか、或は、抵抗膜を合成樹脂フィルムのいずれか片面に形成して誘電体層とその片面側に配置された表面被覆層との間に設け、この抵抗膜形成フィルムの周囲に封止層を形成するか、或いは、抵抗膜を合成樹脂フィルムのいずれか片面に形成して誘電体層の片面側に設け、この抵抗膜形成フィルムの周囲と両面、又は、抵抗膜形成フィルムの周囲と抵抗膜の表面に封止層を形成することにより、抵抗膜を水分を含む外気から封止することも好ましい。   In the radio wave absorber of the present invention, the resistance film is formed on one side of the synthetic resin film, and the resistance film of the resistance film forming film is on one side of the dielectric layer so that the resistance film is on the dielectric layer side. And a sealing layer is formed around the resistive film, or the resistive film is formed on one side of the synthetic resin film and between the dielectric layer and the surface coating layer disposed on the one side. And forming a sealing layer around the resistive film forming film, or forming a resistive film on one side of the synthetic resin film and providing it on one side of the dielectric layer. It is also preferable to seal the resistance film from the outside air containing moisture by forming a sealing layer on the periphery and both surfaces, or on the periphery of the resistance film forming film and the surface of the resistance film.

そして、電波反射体の両側に設けられている誘電体層の電波反射体との反対面側に抵抗膜をそれぞれ設けていること、封止層がシリコーン系又はウレタン系の封止剤で形成したものであること、抵抗膜が極細導電繊維を含んだ膜であって極細導電繊維が凝集することなく分散して互いに接触していること、表面被覆層が紫外線吸収剤を含んだ合成樹脂板であること、抵抗膜、誘電体層、表面被覆層、封止層のいずれもが透視性を有すると共に電波反射体が光を透過して、透視性を有する電波吸収体であることが好ましい。   And, each of the dielectric layers provided on both sides of the radio wave reflector is provided with a resistance film on the opposite side of the radio wave reflector, and the sealing layer is formed of a silicone or urethane type sealant. The resistance film is a film containing ultrafine conductive fibers, the ultrafine conductive fibers are dispersed without contacting each other and are in contact with each other, and the surface coating layer is a synthetic resin plate containing an ultraviolet absorber. It is preferable that the resistance film, the dielectric layer, the surface coating layer, and the sealing layer are all transparent, and the radio wave reflector transmits light so that the radio wave absorber has transparency.

ここで、「凝集することなく」とは、抵抗膜を顕微鏡で観察したとき平均径が０．５μｍ以上の凝集塊がないことを意味し、また、「接触」とは、極細導電繊維が現実に接触している場合と、極細導電繊維が導通可能な微小間隙をあけて接近している場合の双方を意味する。また、透視性とは光学特性であるヘーズが１０％以下であることを意味する。   Here, “without agglomeration” means that there is no agglomerate having an average diameter of 0.5 μm or more when the resistance film is observed with a microscope, and “contact” means that an ultrafine conductive fiber is actually used. It means both the case where it is in contact with the case and the case where the fine conductive fiber is approaching with a small gap that allows conduction. Further, the transparency means that the haze as an optical characteristic is 10% or less.

本発明の電波吸収体のように抵抗膜が水分を含む外気から封止されていると、外気中の水分（湿気）との接触が断たれるため、後述の実験データで裏付けられるように、抵抗膜の表面抵抗率がほぼ一定に保たれる。従って、表面抵抗率の変化（増加・減少）による電波吸収性能の低下が防止され、長期間に亘って初期の良好な電波吸収性能を維持できるので、耐久性及び信頼性が大幅に向上する。   When the resistance film is sealed from the outside air containing moisture like the radio wave absorber of the present invention, contact with moisture in the outside air (humidity) is cut off, so that it is supported by the experimental data described below, The surface resistivity of the resistive film is kept almost constant. Therefore, the deterioration of the radio wave absorption performance due to the change (increase / decrease) in the surface resistivity is prevented, and the initial good radio wave absorption performance can be maintained over a long period of time, so that the durability and reliability are greatly improved.

特に、抵抗膜を誘電体層とその片面側に配置された表面被覆層との間に設けて抵抗膜の周囲に封止層を形成した電波吸収体は、誘電体層と表面被覆層と封止層によって抵抗膜の両面と周囲が確実に封止されて密封状態になるため、抵抗膜と外気中の水分との接触が確実に断たれ、水分との接触に起因する抵抗膜の表面抵抗率の変化（増加・減少）が防止されて耐久性及び信頼性が一層向上する。   In particular, a radio wave absorber in which a resistance film is provided between a dielectric layer and a surface coating layer disposed on one side thereof and a sealing layer is formed around the resistance film has a dielectric layer, a surface coating layer, and a sealing layer. Since both sides and the periphery of the resistance film are securely sealed by the stopper layer, the contact between the resistance film and the moisture in the outside air is reliably cut off, and the resistance of the resistance film due to the contact with the moisture is reduced. The rate change (increase / decrease) is prevented, and durability and reliability are further improved.

また、抵抗膜を誘電体層の片面に設けて抵抗膜の表面と周囲に封止層を形成した電波吸収体は、封止層によって抵抗膜の表面と周囲が確実に封止されると共に、誘電体層によって抵抗膜の裏面も確実に封止されて密封状態になるため、同様に抵抗膜の表面抵抗率の変化（増加・減少）が防止されて耐久性及び信頼性が一層向上する。   In addition, in the radio wave absorber in which the resistance film is provided on one surface of the dielectric layer and the sealing layer is formed on the surface and the periphery of the resistance film, the surface and the periphery of the resistance film are reliably sealed by the sealing layer, Since the back surface of the resistance film is surely sealed and sealed by the dielectric layer, a change (increase / decrease) in the surface resistivity of the resistance film is similarly prevented, and durability and reliability are further improved.

また、抵抗膜を誘電体層の片面側に配置された表面被覆層の該誘電体層との対向面に設けて抵抗膜の表面と周囲に封止層を形成した電波吸収体は、封止層によって抵抗膜の表面と周囲が確実に封止されると共に、裏面被覆層によって抵抗膜の裏面も確実に封止されて密封状態になるため、同様に抵抗膜の表面抵抗率の変化（増加・減少）が防止されて耐久性及び信頼性が一層向上する。   In addition, a radio wave absorber in which a resistance film is provided on the surface of the surface coating layer disposed on one side of the dielectric layer facing the dielectric layer and a sealing layer is formed on and around the resistance film is sealed The surface and the periphery of the resistive film are surely sealed by the layer, and the back surface of the resistive film is also reliably sealed by the back surface coating layer so as to be in a sealed state. -Reduction) is prevented and durability and reliability are further improved.

また、抵抗膜を合成樹脂フィルムのいずれか片面に形成し、この抵抗膜形成フィルムの抵抗膜が誘電体層側となるように誘電体層の片側面に設けて抵抗膜の周囲に封止層を形成した電波吸収体は、抵抗膜の表面が合成樹脂フィルムにより覆われて、誘電体層と封止層と共に抵抗膜を封止した状態にするので、同様に抵抗膜の表面抵抗率の変化（増加・減少）が防止されて耐久性及び信頼性が一層向上する。   Also, a resistance film is formed on one side of the synthetic resin film, and the resistance film of the resistance film forming film is provided on one side of the dielectric layer so that the resistance film is on the dielectric layer side, and a sealing layer is formed around the resistance film. Since the resistance film surface is covered with a synthetic resin film and the resistance film is sealed together with the dielectric layer and the sealing layer, the change in the surface resistivity of the resistance film is similarly achieved. (Increase / decrease) is prevented and durability and reliability are further improved.

また、抵抗膜を合成樹脂フィルムのいずれか片面に形成して誘電体層とその片面側に配置された表面被覆層との間に設け、この抵抗膜形成フィルムの周囲に封止層を形成した電波吸収体は、誘電体層又は表面被覆層によって抵抗膜の表面が確実に封止され、合成樹脂フィルムと表面被覆層又は誘電体層とによって抵抗膜の裏面が二重に封止され、封止層によって抵抗膜の周囲が確実に封止されて密封状態になるため、抵抗膜と外気中の水分との接触が確実に断たれ、水分との接触に起因する抵抗膜の表面抵抗率の変化（増加・減少）が防止されて耐久性及び信頼性が一層向上する。   Also, a resistive film was formed on one side of the synthetic resin film, provided between the dielectric layer and the surface coating layer disposed on the single side, and a sealing layer was formed around the resistive film forming film. In the radio wave absorber, the surface of the resistance film is securely sealed by the dielectric layer or the surface coating layer, and the back surface of the resistance film is double sealed by the synthetic resin film and the surface coating layer or the dielectric layer. Since the periphery of the resistive film is securely sealed by the stopper layer, the contact between the resistive film and the moisture in the outside air is reliably cut off, and the surface resistivity of the resistive film due to the contact with the moisture is reduced. Changes (increase / decrease) are prevented and durability and reliability are further improved.

また、抵抗膜を合成樹脂フィルムのいずれか片面に形成して誘電体層の片面側に設け、この抵抗膜形成フィルムの周囲と両面、又は、抵抗膜形成フィルムの周囲と抵抗膜の表面に封止層を形成した電波吸収体は、封止層によって抵抗膜の表面と周囲が確実に封止され、合成樹脂フィルム又は該フィルムと封止層によって抵抗膜の裏面が確実に封止されて密封状態となるため、同様に抵抗膜の表面抵抗率の変化（増加・減少）が防止されて耐久性及び信頼性が一層向上する。   In addition, a resistive film is formed on one side of the synthetic resin film and provided on one side of the dielectric layer, and sealed around the resistive film forming film or both surfaces, or around the resistive film forming film and the surface of the resistive film. The radio wave absorber having the stop layer is sealed with the sealing layer reliably sealing the surface and the periphery of the resistance film, and the back surface of the resistance film is reliably sealed with the synthetic resin film or the film and the sealing layer. Therefore, the change (increase / decrease) in the surface resistivity of the resistance film is similarly prevented, and the durability and reliability are further improved.

そして、本発明において、電波反射体の両側に設けられている誘電体層の片面側に抵抗膜をそれぞれ設けられていると、両側から伝播してくる電波を中央の電波反射体で反射して吸収することができ、電波反射体を共用できるので、安価な電波吸収体とすることができる。   In the present invention, when a resistive film is provided on one side of the dielectric layer provided on both sides of the radio wave reflector, the radio wave propagating from both sides is reflected by the central radio wave reflector. Since it can be absorbed and a radio wave reflector can be shared, an inexpensive radio wave absorber can be obtained.

また、封止層がシリコーン系又はウレタン系の封止剤で形成された電波吸収体は、その優れた封止性能によって抵抗膜の表面抵抗率の変化（増加・減少）が確実に防止されるため、耐久性や信頼性が顕著に向上する。また、抵抗膜が極細導電繊維を含んだ膜であって、極細導電繊維が凝集することなく分散して互いに接触している電波吸収体は、この極細導電繊維が極めて細いものであるため抵抗膜が良好な透明性を有し、しかも、接触、導通に寄与する極細導電繊維の本数が相対的に多く接触頻度が高いため、その分だけ極細導電繊維の含有量を少なくしても所定の表面抵抗率を確保することが可能であり、極細導電繊維を減らせる分だけ抵抗膜の透明性を更に向上させることができる。   In addition, the radio wave absorber in which the sealing layer is formed of a silicone-based or urethane-based sealant reliably prevents the change (increase / decrease) in the surface resistivity of the resistive film due to its excellent sealing performance. Therefore, durability and reliability are remarkably improved. Further, the resistance film is a film containing ultrafine conductive fibers, and the electromagnetic wave absorbers in which the fine conductive fibers are dispersed without contacting each other and are in contact with each other, the ultrafine conductive fibers are extremely thin, so that the resistive film Has good transparency, and the number of ultra-fine conductive fibers that contribute to contact and conduction is relatively high and the contact frequency is high. The resistivity can be ensured, and the transparency of the resistive film can be further improved by the amount that the ultrafine conductive fibers can be reduced.

そのため、抵抗膜、誘電体層、表面被覆層、封止層が透視性を有するものを選択使用すると共に電波反射体が光を透過するものを選択使用すると、透視性を有する電波吸収体とすることができる。このような透視性を有する電波吸収体は、これを通して向こう側を見ることもできるし、その周囲を明るくすることもできる。更に、表面被覆層が紫外線吸収剤を含んだ合成樹脂板である電波吸収体は、屋外で使用しても、この合成樹脂板によって抵抗膜や誘電体層が紫外線等から保護されるので耐候性が向上する。   Therefore, if a resistive film, a dielectric layer, a surface coating layer, and a sealing layer are selectively used, and a radio wave reflector that transmits light is selectively used, a radio wave absorber having transparency is obtained. be able to. The radio wave absorber having such transparency can be seen through the side, and the surroundings can be brightened. Furthermore, even if the radio wave absorber, whose surface coating layer is a synthetic resin plate containing an ultraviolet absorber, is used outdoors, the synthetic resin plate protects the resistance film and dielectric layer from ultraviolet rays and the like, so that it is weather resistant. Will improve.

以下、図面を参照して本発明の具体的な実施形態を詳述する。   Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

図１は本発明の一実施形態に係る電波吸収体の断面図、図１３の（ａ）（ｂ）（ｃ）は同電波吸収体の抵抗膜を示す概略断面図、図１４は同抵抗膜のカーボンナノチューブを正面から見た分散状態を示す模式図である。   FIG. 1 is a cross-sectional view of a radio wave absorber according to an embodiment of the present invention, FIGS. 13A, 13B, and 13C are schematic cross-sectional views showing a resistance film of the radio wave absorber, and FIG. It is a schematic diagram which shows the dispersion state which looked at the carbon nanotube from the front.

この電波吸収体Ａは、透視性の誘電体層１とその片面側（表面側：電波の入射する面側）に配置された透視性の表面被覆層４との間に透視性の抵抗膜３が設けられている。そして、この抵抗膜３の周囲には透視性或は透光性又は不透明な封止層６が形成され、この封止層６によって表面被覆層４と誘電体層１との周縁部同士が接合されている。また、誘電体層１の反対面側（裏面側）には光を透過する電波反射体２が設けられ、この電波反射体２の裏面側には透視性の裏面被覆層５が設けられ、これら誘電体層１と電波反射体２と裏面被覆層５とが接着剤などで一体化されている。   The radio wave absorber A includes a translucent resistive film 3 between the translucent dielectric layer 1 and the translucent surface covering layer 4 disposed on one side (surface side: the surface on which radio waves are incident). Is provided. A transparent, translucent, or opaque sealing layer 6 is formed around the resistance film 3, and the peripheral portions of the surface coating layer 4 and the dielectric layer 1 are bonded to each other by the sealing layer 6. Has been. A radio wave reflector 2 that transmits light is provided on the opposite side (back side) of the dielectric layer 1, and a transparent back surface coating layer 5 is provided on the back side of the radio wave reflector 2. Dielectric layer 1, radio wave reflector 2 and back surface coating layer 5 are integrated with an adhesive or the like.

この電波吸収体Ａは、上記のように誘電体層１と表面被覆層４によって抵抗膜３の表裏両面が封止されると共に、封止層６によって抵抗膜３の周囲が封止されて密封状態になっているため、抵抗膜３は水分を含む外気から遮断され、外気中の水分との接触に起因する抵抗膜３の表面抵抗率の変化（増加・減少）が確実に防止される。そして、表面被覆層４、抵抗膜３、誘電体層１、裏面被覆層５がそれぞれ透視性を有し、電波反射体２が光を透過するので、これらが積層された電波吸収体Ａは透視性を有するものとなる。   In the radio wave absorber A, both the front and back surfaces of the resistance film 3 are sealed by the dielectric layer 1 and the surface coating layer 4 as described above, and the periphery of the resistance film 3 is sealed by the sealing layer 6 and sealed. Since the resistance film 3 is in the state, the resistance film 3 is shielded from the outside air containing moisture, and the change (increase / decrease) in the surface resistivity of the resistance film 3 due to the contact with the moisture in the outside air is surely prevented. And since the surface coating layer 4, the resistance film 3, the dielectric material layer 1, and the back surface coating layer 5 have transparency, and the radio wave reflector 2 transmits light, the radio wave absorber A in which these layers are laminated is fluoroscopic. It will have a sex.

上記の電波吸収体Ａにおいて、表面被覆層４は、抵抗膜３の封止を確実にするために、抵抗膜３の周縁部を封止する封止層６で密着接合して誘電体層１と一体化することが必要であるが、電波反射体２や裏面被覆層５は誘電体層１の裏面側に単に重ねるだけでもよい。但し、この実施形態のように、誘電体層１と電波反射体２と裏面被覆層５とが接着剤などで一体化されていると、取扱性が向上するので好ましい。また、抵抗膜３を誘電体層１と表面被覆層４との間に設けるには、誘電体層１の片面（表面）に抵抗膜３を予め形成してその上に表面被覆層４を重ねる方法を採用してもよいし、表面被覆層４の誘電体層１との対向面に抵抗膜３を予め形成して誘電体層１の上に重ねる方法を採用してもよいし、或は、予め形成された抵抗膜３を誘電体層１と表面被覆層４との間に介在させる方法を採用してもよい。   In the above-described radio wave absorber A, the surface coating layer 4 is closely bonded with the sealing layer 6 that seals the peripheral portion of the resistance film 3 in order to ensure the sealing of the resistance film 3. However, the radio wave reflector 2 and the back surface coating layer 5 may simply be superimposed on the back surface side of the dielectric layer 1. However, as in this embodiment, it is preferable that the dielectric layer 1, the radio wave reflector 2, and the back surface coating layer 5 are integrated with an adhesive or the like because the handling property is improved. In order to provide the resistance film 3 between the dielectric layer 1 and the surface coating layer 4, the resistance film 3 is formed in advance on one surface (surface) of the dielectric layer 1 and the surface coating layer 4 is overlaid thereon. A method may be employed, or a method may be employed in which a resistive film 3 is formed in advance on the surface of the surface coating layer 4 facing the dielectric layer 1 and overlaid on the dielectric layer 1, or Alternatively, a method of interposing the previously formed resistance film 3 between the dielectric layer 1 and the surface coating layer 4 may be employed.

上記の誘電体層１は高誘電率の合成樹脂やガラスなどからなるものであって、この誘電体層１の厚さは、用途や実用強度を考慮して０．５〜１５ｍｍの範囲内で、λ／４電波吸収体理論（λ：誘電体層１内での電波の波長）に基づいて設計されている。二次曲げ加工性を考慮すると、ガラスよりも熱可塑性合成樹脂で誘電体層１を形成することが望ましく、更に、屋外で使用する際の耐熱性や透視性を考慮すると、融点や光線透過率が高いアクリル系樹脂（メチルメタクリレート等）、オレフィン系樹脂（ポリエチレン、ポリプロピレン、シクロオレフィンポリマー等）、ポリエステル系樹脂（ポリカーボネート、ポリエチレンテレフタレート等）などで誘電体層１を形成することが望ましい。これらの中で、ポリカーボネート樹脂は機械的強度に優れ、全光線透過率が８５％以上（厚さ３ｍｍ）、ヘーズが１．０％以下と透明性に優れているので、屋外で使用する透視性ないし透明な電波吸収体の誘電体層１としては特に好ましく用いられる。なお、ポリカーボネートはメチルメタクリレート樹脂に比べ多少耐候性に劣るが、紫外線吸収剤等を添加したり、表面被覆層４として後述する耐候性に優れた樹脂板を使用することによって、実用に十分な耐候性を付与できる。   The dielectric layer 1 is made of a synthetic resin or glass having a high dielectric constant, and the thickness of the dielectric layer 1 is within a range of 0.5 to 15 mm in consideration of use and practical strength. Λ / 4 wave absorber theory (λ: wavelength of radio wave in the dielectric layer 1). In view of the secondary bending workability, it is desirable to form the dielectric layer 1 with a thermoplastic synthetic resin rather than glass, and further considering the heat resistance and transparency when used outdoors, the melting point and light transmittance. It is desirable to form the dielectric layer 1 with an acrylic resin (such as methyl methacrylate), an olefin resin (polyethylene, polypropylene, cycloolefin polymer, etc.), a polyester resin (polycarbonate, polyethylene terephthalate, etc.) or the like that is high. Among these, polycarbonate resin has excellent mechanical strength, total light transmittance is 85% or more (thickness 3 mm), and haze is 1.0% or less. The dielectric layer 1 of a transparent wave absorber is particularly preferably used. Polycarbonate is somewhat inferior in weather resistance compared to methyl methacrylate resin, but by adding a UV absorber or using a resin plate having excellent weather resistance, which will be described later, as the surface coating layer 4, weather resistance sufficient for practical use is obtained. Sex can be imparted.

このような合成樹脂やガラスで作製された誘電体層１は、抵抗膜３の裏面を封止して裏面から水分を含んだ外気が浸透するのを阻止するという役目も果たしている。   The dielectric layer 1 made of such a synthetic resin or glass also plays a role of sealing the back surface of the resistance film 3 and preventing permeation of outside air containing moisture from the back surface.

上記の電波反射体２は光を透過する導電材からなるものであって、例えば４〜２５０メッシュ程度の目を備えた導電メッシュ材や金属メッシュ材、或いは、金属金網や金属格子、或いは、開口率の大きいパンチングメタル、或いは、表面抵抗率が１０Ω／□以下の透視性乃至透明な導電膜を形成した透明フィルムなどが好ましく使用される。   The radio wave reflector 2 is made of a conductive material that transmits light. For example, a conductive mesh material or a metal mesh material having a mesh of about 4 to 250 mesh, a metal wire mesh, a metal grid, or an opening. A punching metal having a high rate or a transparent film on which a transparent or conductive film having a surface resistivity of 10Ω / □ or less is formed is preferably used.

上記の抵抗膜３は、周波数帯域１〜１８ＧＨｚの電波吸収に適するように、自由空間の電波特性インピーダンスに合致する３７７Ω／□を目標値とする表面抵抗率を備えた透視性、好ましくは透明な薄膜であって、具体的には３７７±３０Ω／□の表面抵抗率を備えたＩＴＯ等の金属酸化物の蒸着膜や、極細導電繊維を含んだ同様の表面抵抗率を有する薄膜からなるものが好ましく用いられ、図１に示す実施形態の電波吸収体Ａでは、後者の極細導電繊維を含んだ抵抗膜３が採用されている。   The resistive film 3 is transparent, preferably transparent, having a surface resistivity with a target value of 377 Ω / □ that matches the radio wave characteristic impedance of free space so as to be suitable for radio wave absorption in the frequency band of 1 to 18 GHz. A thin film, specifically, a vapor-deposited film of a metal oxide such as ITO having a surface resistivity of 377 ± 30Ω / □, or a thin film having a similar surface resistivity including ultrafine conductive fibers In the radio wave absorber A of the embodiment shown in FIG. 1, which is preferably used, the latter resistive film 3 including ultrafine conductive fibers is employed.

この極細導電繊維を含んだ抵抗膜３は、極細導電繊維を分散させた塗液を塗布して形成した薄膜であって、極細導電繊維の含有量、塗膜厚み、分散状態などの諸条件を調節することにより、３７７±３０Ω／□の表面抵抗率が得られるようにしたものである。この実施形態では、極細導電繊維としてカーボンナノチューブを使用し、カーボンナノチューブの目付け量が３０〜４５０ｍｇ／ｍ２、好ましくは３０〜２５０ｍｇ／ｍ２となるように、塗液のカーボンナノチューブの含有量や塗膜の厚みなどを調節して塗布することで、３７７±３０Ω／□の表面抵抗率を備えた抵抗膜３を形成している。このような抵抗膜３は、カーボンナノチューブの目付け量（含有量、濃度）等に対応して抵抗膜３の表面抵抗率がほぼ定まり、表面抵抗率の大きいバラツキが生じにくい。尚、上記の目付け量は、抵抗膜３を電子顕微鏡で観察し、その平面面積に占めるカーボンナノチューブの面積割合を測定し、これに電子顕微鏡で観察した厚みとカーボンナノチューブの比重（グラファイトの文献値２．１〜２．３の平均値２．２を採用）を乗算して算出した値である。 The resistance film 3 including the ultrafine conductive fiber is a thin film formed by applying a coating liquid in which the ultrafine conductive fiber is dispersed, and various conditions such as the content of the ultrafine conductive fiber, the thickness of the coating film, and the dispersion state are determined. By adjusting the surface resistivity, a surface resistivity of 377 ± 30Ω / □ can be obtained. In this embodiment, carbon nanotubes are used as the ultrafine conductive fibers, and the carbon nanotube content in the coating solution is such that the basis weight of the carbon nanotubes is 30 to 450 mg / m 2 , preferably 30 to 250 mg / m 2. The resistance film 3 having a surface resistivity of 377 ± 30 Ω / □ is formed by adjusting the thickness of the coating film. In such a resistance film 3, the surface resistivity of the resistance film 3 is substantially determined corresponding to the basis weight (content and concentration) of the carbon nanotubes, and variations in the surface resistivity are less likely to occur. The weight per unit area is determined by observing the resistive film 3 with an electron microscope, measuring the area ratio of carbon nanotubes in the planar area, and measuring the thickness and specific gravity of the carbon nanotubes (document values of graphite). The value calculated by multiplying the average value 2.2 of 2.1 to 2.3).

極細導電繊維としては、上記のカーボンナノチューブが最も好ましく用いられるが、その他の繊維であっても抵抗膜３の表面抵抗率を３７７±３０Ω／□にすることができるものであれば制限なく使用可能である。例えば、カーボンナノホーン、カーボンナノワイヤー、カーボンナノファイバー、グラファイトフィブリルなどの極細長炭素繊維、白金、金、銀、ニッケル、シリコンなどの金属ナノチューブ、ナノワイヤーなどの極細長金属繊維、酸化亜鉛などの金属酸化物ナノチューブ、ナノワイヤーなどの極細長金属酸化物繊維などの、直径が０．３〜１００ｎｍで長さが０．１〜２０μｍ、好ましくは０．１〜１０μｍのものが用いられる。   As the ultrafine conductive fiber, the above carbon nanotube is most preferably used, but other fibers can be used without limitation as long as the surface resistivity of the resistive film 3 can be 377 ± 30Ω / □. It is. For example, carbon nanotubes such as carbon nanohorns, carbon nanowires, carbon nanofibers, and graphite fibrils, metal nanotubes such as platinum, gold, silver, nickel, and silicon, ultrafine metal fibers such as nanowires, and metals such as zinc oxide An ultrafine metal oxide fiber such as an oxide nanotube or nanowire having a diameter of 0.3 to 100 nm and a length of 0.1 to 20 μm, preferably 0.1 to 10 μm is used.

抵抗膜３のカーボンナノチューブは凝集することなく分散して互いに接触しており、具体的にはカーボンナノチューブが１本ずつ分離した状態で、もしくは、複数本集まって束になったものが１束ずつ分離した状態で分散して互いに接触している。そして、抵抗膜３がカーボンナノチューブとバインダーからなるものであると、図１３（ａ）に示すように、カーボンナノチューブ３ａはバインダー３ｂの内部に上記の分散状態で３次元構造をなして分散して互いに接触しているか、或いは、図１３（ｂ）に示すように、カーボンナノチューブ３ａの一部がバインダー３ｂ中に入り込み他の部分がバインダー３ｂの表面から突出ないし露出して上記の分散状態で分散して互いに接触しているか、或いは、一部のカーボンナノチューブ３ａが図１３（ａ）のようにバインダー３ｂの内部に、他のカーボンナノチューブ３ａが図１３（ｂ）のようにバインダー３ｂの表面から突出ないし露出して上記分散状態で３次元構造をなして分散して互いに接触している。また、抵抗膜３がバインダーを含まないと、図１３（ｃ）に示すように、カーボンナノチューブが上記分散状態で分散して互いに接触して、カーボンナノチューブの３次元構造の層となっている。
なお、上記バインダーとしては、透明な合成樹脂が透視性の抵抗膜３を得るうえで好ましい。 The carbon nanotubes of the resistive film 3 are dispersed without contacting each other and are in contact with each other. Specifically, the carbon nanotubes are separated one by one, or a bundle of bundles of multiple carbon nanotubes. They are dispersed and in contact with each other. If the resistive film 3 is made of carbon nanotubes and a binder, as shown in FIG. 13A, the carbon nanotubes 3a are dispersed in the binder 3b in the above-mentioned dispersed state in a three-dimensional structure. As shown in FIG. 13B, a part of the carbon nanotube 3a enters the binder 3b and the other part protrudes or is exposed from the surface of the binder 3b and dispersed in the above dispersed state. Or a part of the carbon nanotubes 3a from inside the binder 3b as shown in FIG. 13 (a) and the other carbon nanotubes 3a from the surface of the binder 3b as shown in FIG. 13 (b). Protruding or exposed to form a three-dimensional structure in the dispersed state and are in contact with each other. If the resistive film 3 does not contain a binder, as shown in FIG. 13C, the carbon nanotubes are dispersed in the above dispersed state and are in contact with each other to form a three-dimensional layer of carbon nanotubes.
As the binder, a transparent synthetic resin is preferable for obtaining the transparent resistive film 3.

これらのカーボンナノチューブ３ａの正面から見た分散状態を模式的に示したものが図１４であって、この図１４から理解できるように、カーボンナノチューブ３ａは多少曲がっているが、１本ずつ或いは１束ずつ分離し、互いに複雑に絡み合うことなく、即ち凝集することなく、単純に交差した状態で抵抗膜３の内部或いは表面に分散し、それぞれの交点で接触している。尚、カーボンナノチューブ３ａは完全に１本ずつ或いは１束ずつ分離して分散している必要はなく、一部に絡み合った小さな凝集塊があってもよいが、既述したように「凝集することなく」とは長径と短径の平均値が０．５μｍ以上の凝集塊がないことを意味するものであるから、存在する凝集塊の平均径は０．５μｍ未満であることが必要である。   FIG. 14 schematically shows the dispersion state of these carbon nanotubes 3a as viewed from the front. As can be understood from FIG. 14, the carbon nanotubes 3a are slightly bent, but each one or 1 The bundles are separated and dispersed in the inside or the surface of the resistive film 3 in a simply intersected state without being intricately entangled with each other, that is, without agglomerating, and in contact with each other. The carbon nanotubes 3a do not have to be separated and dispersed completely one by one or one bundle, and there may be small agglomerates that are intertwined with each other. “None” means that there is no agglomerate having an average value of the major axis and the minor axis of 0.5 μm or more, and therefore the average diameter of the agglomerates that are present needs to be less than 0.5 μm.

このように、極細導電繊維であるカーボンナノチューブ３ａが抵抗膜３内で多少曲がって１本ずつ或は１束ずつ分離して、互いに複雑に絡み合うことなく３次元構造をなして分散していると、抵抗膜３を曲げてもカーボンナノチューブ３ａが伸びたりずれたりするだけであるのでお互いの接触が保たれる。そのため、この電波吸収体Ａを曲げても表面抵抗率の増加が殆どなく、電波吸収性能を維持することができるので、湾曲した電波吸収体を作製できるし、施工現場で曲げて使用することもできる。   In this way, when the carbon nanotubes 3a, which are ultrafine conductive fibers, are slightly bent in the resistive film 3 and separated one by one or one bundle, they are dispersed in a three-dimensional structure without being complicatedly entangled with each other. Even if the resistance film 3 is bent, the carbon nanotubes 3a only extend or shift, so that mutual contact is maintained. Therefore, even if this radio wave absorber A is bent, there is almost no increase in surface resistivity, and radio wave absorption performance can be maintained. Therefore, a curved radio wave absorber can be produced, and it can be bent and used at the construction site. it can.

カーボンナノチューブ３ａは直径が０．３〜８０ｎｍと極めて細いため、これを前記の目付け量に相当する量だけ含んだ抵抗膜３は透視性が良好であるが、特に上記のような分散状態でカーボンナノチューブ３ａが分散していると、凝集しないで接触、導通に寄与するカーボンナノチューブ３ａの本数が相対的に増え、チューブ相互の接触頻度が高くなるため、その分だけカーボンナノチューブ３ａの目付け量を少なくしても前記の表面抵抗率（３７７±３０Ω／□）を確保できるようになり、このカーボンナノチューブ３ａを少なくできる分だけ透視性を更に向上させることが可能となる。ちなみに、前記の目付け量に相当する量のカーボンナノチューブを含んだ３７７±３０Ω／□の表面抵抗率を有する抵抗膜３の光線透過率（分光光度計による５５０ｎｍの光の透過率）は、８７％前後であり、それゆえ透視性の良い誘電体層１と透光量の多い電波反射体２を選択して電波吸収体を作製すれば、全光線透過率が４０％以上、ヘーズが１０％以下の透視性を有する電波吸収体を確実に得ることができる。より好ましくは全光線透過率が５０％以上で、ヘーズは１０％以下である。   Since the carbon nanotube 3a has an extremely thin diameter of 0.3 to 80 nm, the resistance film 3 containing the carbon nanotube 3a in an amount corresponding to the weight per unit area has good transparency. If the nanotubes 3a are dispersed, the number of carbon nanotubes 3a that contribute to contact and conduction without aggregation is relatively increased, and the frequency of contact between the tubes is increased. Therefore, the basis weight of the carbon nanotubes 3a is reduced accordingly. Even so, the surface resistivity (377 ± 30Ω / □) can be ensured, and the transparency can be further improved by the amount of the carbon nanotubes 3a. Incidentally, the light transmittance (transmittance of light at 550 nm by a spectrophotometer) of the resistive film 3 having a surface resistivity of 377 ± 30Ω / □ containing carbon nanotubes in an amount corresponding to the weight per unit area is 87%. If a radio wave absorber is prepared by selecting the dielectric layer 1 having good transparency and the radio wave reflector 2 having a large amount of light transmission, the total light transmittance is 40% or more and the haze is 10% or less. Thus, it is possible to reliably obtain a radio wave absorber having transparency. More preferably, the total light transmittance is 50% or more and the haze is 10% or less.

上記のカーボンナノチューブ３ａには、中心軸線の周りに複数のカーボン壁を同心的に備えた多層カーボンナノチューブや、中心軸線の周りに単独のカーボン壁を備えた単層カーボンナノチューブがある。前者の多層カーボンナノチューブは、中心軸線の周りに直径が異なる複数の円筒状に閉じたカーボン壁を有する多層になって構成されたものと、渦巻き状に多層に形成されているものとがある。その中でも、好ましい多層カーボンナノチューブは、２〜３０層、より好ましくは２〜１５層重なったものが用いられる。そのような多層カーボンナノチューブを前記の分散状態で分散させると、既述したように光線透過率の良い抵抗膜３が形成される。多層カーボンナノチューブは１本ずつ分離した状態で分散しているものが殆どであるが、２層ないし３層カーボンナノチューブは、束になって分散している場合もある。   The carbon nanotubes 3a include multi-walled carbon nanotubes having a plurality of carbon walls concentrically around the central axis, and single-walled carbon nanotubes having a single carbon wall around the central axis. The former multi-walled carbon nanotube includes a multi-walled carbon wall having a plurality of cylindrical carbon walls with different diameters around a central axis, and a multi-walled carbon nanotube formed in a spiral shape. Among them, preferable multi-walled carbon nanotubes are those having 2 to 30 layers, more preferably 2 to 15 layers. When such multi-walled carbon nanotubes are dispersed in the dispersed state, the resistance film 3 having a good light transmittance is formed as described above. Most of the multi-walled carbon nanotubes are dispersed in a state of being separated one by one, but the two- or three-layer carbon nanotubes may be dispersed in a bundle.

一方、後者の単層カーボンナノチューブは、上記のようにカーボン壁が中心軸線の周りに円筒状に閉じた単層のチューブである。このような単層カーボンナノチューブは通常２本以上が集まって束になった状態で存在し、その束が１束ずつ分離して、束同士が複雑に絡み合うことなく凝集せずに単純に交差した状態で抵抗膜３の内部もしくは表面に分散され、それぞれの交点で接触している。そして、好ましくは１０〜５０本の単層カーボンナノチューブが集まって束になったものが用いられる。なお、１本ずつ分離した状態で分散している場合も当然本発明に含まれる。   On the other hand, the latter single-walled carbon nanotube is a single-walled tube in which the carbon wall is closed in a cylindrical shape around the central axis as described above. Such single-walled carbon nanotubes usually exist in a bundle of two or more, and the bundles are separated one by one, and the bundles simply intersect without agglomerating without complicated entanglement. In the state, it is dispersed inside or on the surface of the resistance film 3 and is in contact at each intersection. Preferably, a bundle of 10 to 50 single-walled carbon nanotubes is used. Note that the present invention naturally includes a case where the particles are dispersed one by one.

カーボンナノチューブの分散性を高めるためには、抵抗膜３中に分散剤を含有させることが望ましい。分散剤としては、酸性ポリマーのアルキルアンモニウム塩溶液、３級アミン修飾アクリル共重合物、ポリオキシエチレン−ポリオキシプロピレン共重合物などの高分子系分散剤やカップリング剤などが好ましく使用される。   In order to improve the dispersibility of the carbon nanotubes, it is desirable to include a dispersant in the resistance film 3. As the dispersant, a polymer dispersant such as an alkyl ammonium salt solution of an acidic polymer, a tertiary amine-modified acrylic copolymer, a polyoxyethylene-polyoxypropylene copolymer, a coupling agent, or the like is preferably used.

抵抗膜３は、バインダーのないカーボンナノチューブのみからなる薄膜であってもよいが、カーボンナノチューブの脱落防止性、表面抵抗率の安定性、透明性などのために、バインダーを使用することが好ましい。このバインダーとしては、熱可塑性樹脂、例えばポリ塩化ビニル、ポリメチルメタクリレート、ニトロセルロース、塩素化ポリエチレン、塩素化ポリプロピレン、フッ化ビニリデンなどのフッ素樹脂などの透明な樹脂が使用され、また、熱や紫外線や電子線や放射線で硬化する硬化性樹脂、例えばメラミンアクリレート、ウレタンアクリレート、エポキシ樹脂、ポリイミド樹脂、アクリル変性シリケートなどのシリコーン樹脂などの透明な樹脂も使用される。なお、このバインダーとしては透光性樹脂を使用してもよく、このような樹脂を使用しても抵抗膜３を薄くすることで透視性を有する抵抗膜３とすることができる。また、このバインダーにはコロイダルシリカのような無機材を添加してもよく、その場合は表面硬度や耐摩耗性に優れた抵抗膜３が形成される。   The resistance film 3 may be a thin film made of only carbon nanotubes without a binder, but it is preferable to use a binder for preventing the carbon nanotubes from falling off, stabilizing the surface resistivity, transparency, and the like. As this binder, thermoplastic resins such as transparent resins such as polyvinyl chloride, polymethyl methacrylate, nitrocellulose, chlorinated polyethylene, chlorinated polypropylene, and vinylidene fluoride are used, and heat and ultraviolet rays are used. Also, a transparent resin such as a curable resin that is cured by electron beam or radiation, such as a silicone resin such as melamine acrylate, urethane acrylate, epoxy resin, polyimide resin, or acrylic-modified silicate is used. Note that a translucent resin may be used as the binder, and even if such a resin is used, the resistive film 3 having transparency can be obtained by thinning the resistive film 3. In addition, an inorganic material such as colloidal silica may be added to the binder, and in this case, the resistance film 3 having excellent surface hardness and wear resistance is formed.

抵抗膜３の表面を覆う表面被覆層４は、誘電体層１と同様の透視性を有する合成樹脂やガラスなどからなる層であって、この表面被覆層４は、抵抗膜３の表面を水分を含む外気から封止する目的と、抵抗膜３や誘電体層１を直射日光による紫外線劣化から保護する目的で設けられたものである。さらに、合成樹脂からなる表面被覆層４であると、飛来物衝突による破損も防止することもできる。そのため、表面被覆層４の厚さは、１〜４ｍｍ程度の耐候性に優れた強度のある透視性を有するアクリル系樹脂板や、紫外線吸収剤を含有させて耐候性を高めた同程度の厚みを有する透視性を有するポリエステル系、オレフィン系等の合成樹脂板が好ましく使用される。特に、紫外線吸収剤を含有させたポリカーボネート樹脂は機械的強度に、優れ、耐候性や透明性も良好であるので、表面被覆層４として極めて好ましい。   The surface coating layer 4 covering the surface of the resistance film 3 is a layer made of a synthetic resin or glass having the same transparency as the dielectric layer 1, and the surface coating layer 4 covers the surface of the resistance film 3 with moisture. And for the purpose of protecting the resistance film 3 and the dielectric layer 1 from ultraviolet degradation due to direct sunlight. Furthermore, the surface coating layer 4 made of synthetic resin can also prevent damage due to flying object collision. Therefore, the thickness of the surface coating layer 4 is the same thickness as the weather resistance improved by including the acrylic resin board which has the transparency which was excellent in the weather resistance of about 1-4 mm, and the intensity | strength, and the ultraviolet absorber. A polyester-based, olefin-based, or other synthetic resin plate having transparency is preferably used. In particular, a polycarbonate resin containing an ultraviolet absorber is extremely preferable as the surface coating layer 4 because of its excellent mechanical strength and good weather resistance and transparency.

また、電波反射体２を覆う裏面被覆層５は、電波反射体２や誘電体層１や抵抗膜３を飛来物衝突による破損や直射日光による紫外線劣化から保護する目的で設けられたものであって、表面被覆層４と同様の樹脂板、即ち、厚さ１〜４ｍｍ程度の耐候性に優れた強度のある透視性を有するアクリル系樹脂板、紫外線吸収剤を含有させて耐候性を高めた同程度の厚みを有する透視性を有するポリエステル系、オレフィン系等の合成樹脂板、特に、紫外線吸収剤を含有させたポリカーボネート樹脂などが好ましく用いられる。   Further, the back surface coating layer 5 covering the radio wave reflector 2 is provided for the purpose of protecting the radio wave reflector 2, the dielectric layer 1 and the resistance film 3 from damage caused by flying object collisions and UV deterioration due to direct sunlight. In addition, the same resin plate as the surface coating layer 4, that is, an acrylic resin plate having a thickness of about 1 to 4 mm with excellent weather resistance and high transparency, and an ultraviolet absorber were added to improve weather resistance. A polyester resin or olefin synthetic resin plate having the same degree of transparency and particularly a polycarbonate resin containing an ultraviolet absorber is preferably used.

抵抗膜３の周囲を封止する封止層６は、抵抗膜３に対する周囲からの外気中の水分の浸透を阻止して抵抗膜３の表面抵抗率の経時的な変化（増加・減少）を防止するものであって、例えば、ポリウレタン系、エチレン−酢酸ビニル共重合体系、エチレンモノカルボン酸ビニルエステル共重合体系、エチレン−アクリル酸ビニルエステル共重合体系などのホットメルトシートや、シリコーン系、エポキシ系、アクリル系、オルガノポリシロキサン系、カルバミン酸エステル系、ビニル系、加水分解性シリル基系、シリル化ウレタン系、ポリオキシアルキレン重合体系などの硬化型のシーリング剤や、樹脂を溶剤に溶かした合成樹脂塗液などの封止剤から形成されるものである。このうち、比較的穏やかな加熱条件で軟化溶融して粘着性ないし接着性を発現する封止性能に優れたポリウレタン系のホットメルトシートや、室温から１００℃未満の温度域で粘着性ないし接着性を有し優れた封止性能を発揮するシリコーン系シーリング剤が特に好ましく使用される。これらの封止剤は無色透明のものを使用することが好ましいが、この実施形態の透視性電波吸収体Ａのように抵抗膜３の周囲を封止する場合や、後述する図６の実施形態のように電波吸収体Ｆなどの周囲の端面を封止する場合は、不透明の封止剤を使用してもよい。   The sealing layer 6 that seals the periphery of the resistance film 3 prevents the penetration of moisture in the outside air from the periphery to the resistance film 3, thereby changing the surface resistivity of the resistance film 3 over time (increase / decrease). For example, hot melt sheets such as polyurethane, ethylene-vinyl acetate copolymer, ethylene monocarboxylic acid vinyl ester copolymer, ethylene-acrylic acid vinyl ester copolymer, silicone, epoxy Curable sealing agents such as acrylic, acrylic, organopolysiloxane, carbamic acid ester, vinyl, hydrolyzable silyl group, silylated urethane, polyoxyalkylene polymer, etc. It is formed from a sealing agent such as a synthetic resin coating solution. Among them, polyurethane-based hot-melt sheets with excellent sealing performance that are softened and melted under relatively mild heating conditions and exhibit adhesiveness or adhesiveness, and adhesiveness or adhesiveness in the temperature range from room temperature to less than 100 ° C In particular, a silicone-based sealing agent that exhibits excellent sealing performance is preferably used. These sealing agents are preferably colorless and transparent, but when sealing the periphery of the resistance film 3 as in the case of the transparent wave absorber A of this embodiment, or the embodiment of FIG. 6 described later. In the case of sealing the peripheral end face such as the radio wave absorber F as described above, an opaque sealant may be used.

また、上記の封止層６に用いられるホットメルトシート、シーリング剤、樹脂塗液などの封止剤は、表面被覆層４、抵抗膜３、誘電体層１、電波反射体２、裏面被覆層５を接合一体化する場合に接着剤としても使用される。この場合、これらの界面の全部を上記接着剤で接合一体化した電波吸収体は、それぞれの接合界面での光の散乱が少なくなり、電波吸収体の透視性を向上させ、優れた透視性を有する電波吸収体Ａとすることができる。なお、表面被覆層４、誘電体層１、電波反射体２、裏面被覆層５とをボルトなどの固定具で固定することにより、これらの各層を一体化してもよい。   Moreover, sealing agents, such as a hot-melt sheet used for the said sealing layer 6, sealing agent, and resin coating liquid, are the surface coating layer 4, the resistive film 3, the dielectric material layer 1, the electromagnetic wave reflector 2, and a back surface coating layer. It is also used as an adhesive when 5 is joined and integrated. In this case, the radio wave absorber in which all of these interfaces are bonded and integrated with the above adhesive reduces light scattering at each bonded interface, improves the transparency of the radio wave absorber, and provides excellent transparency. It can be set as the electromagnetic wave absorber A which has. In addition, you may integrate these each layer by fixing the surface coating layer 4, the dielectric material layer 1, the electromagnetic wave reflector 2, and the back surface coating layer 5 with fixing tools, such as a volt | bolt.

以上のような電波吸収体Ａは、例えば次の方法で製造することができる。先ず、カーボンナノチューブなどの極細導電繊維と、溶媒と、必要に応じて前記バインダーと、必要に応じて前記の分散剤とを充分混合して塗液を調製する。そして、前記の合成樹脂板等からなる誘電体層１の片面（表面）、又は、前記の合成樹脂板からなる表面被覆層４の誘電体層１との対向面に、その周縁部を除いて上記の塗液を塗布して表面抵抗率が３７７±３０Ω／□の抵抗膜３を形成する。次いで、この抵抗膜３の周囲の誘電体層１又は表面被覆層４の周縁部表面に封止層６として幅狭のホットメルトシートを配置して、誘電体層１と表面被覆層４を重ねる一方、誘電体層１の反対面に電波反射体２を重ねて、その周縁部に接着剤として例えば上記のホットメルトシートを配置し、その上（裏面）に前記の合成樹脂板からなる裏面被覆層５を重ねる。そして、この積層物を上下の艶板で挟みながら加熱してホットメルトシートを軟化溶融させることにより、抵抗膜３の周囲を封止すると共に、抵抗膜３を覆う表面被覆層４と誘電体層１の周縁部同士を接合し、同時に誘電体層１の反対面に電波反射体２と裏面被覆層５を接合して、電波吸収体Ａを製造する。このようにして得られる電波吸収体Ａは、その全光線透過率を４０％以上、ヘーズを１０％以下にすることでき、良好な透視性（視認性）を有するものが得られる。   The radio wave absorber A as described above can be manufactured, for example, by the following method. First, a coating liquid is prepared by sufficiently mixing ultrafine conductive fibers such as carbon nanotubes, a solvent, the binder as necessary, and the dispersant as necessary. And the peripheral part is remove | excluded in the one surface (surface) of the dielectric material layer 1 which consists of the said synthetic resin board etc., or the opposing surface with the dielectric material layer 1 of the surface coating layer 4 which consists of the said synthetic resin board. The above-described coating liquid is applied to form a resistance film 3 having a surface resistivity of 377 ± 30Ω / □. Next, a narrow hot melt sheet is disposed as the sealing layer 6 on the peripheral surface of the dielectric layer 1 or the surface coating layer 4 around the resistive film 3, and the dielectric layer 1 and the surface coating layer 4 are overlapped. On the other hand, the radio wave reflector 2 is overlapped on the opposite surface of the dielectric layer 1, and the above-mentioned hot melt sheet is disposed as an adhesive on the peripheral edge thereof, and the back surface coating made of the above synthetic resin plate is provided thereon (back surface). Layer 5 is overlaid. Then, the laminate is heated while sandwiched between upper and lower gloss plates to soften and melt the hot melt sheet, thereby sealing the periphery of the resistance film 3 and the surface coating layer 4 and the dielectric layer covering the resistance film 3 The radio wave absorbers A are manufactured by bonding the peripheral portions of 1 and the radio wave reflector 2 and the back surface coating layer 5 to the opposite surfaces of the dielectric layer 1 at the same time. The radio wave absorber A obtained in this way can have a total light transmittance of 40% or more and a haze of 10% or less, and can have a good transparency (visibility).

なお、透視性を有さないが透光性を有する電波吸収体Ａとしたい場合には、例えば、誘電体層１や表面被覆層４や裏面被覆層５として予め光拡散剤や充填剤を添加したものを用いたり、或いは、表面被覆層４や裏面被覆層５の外表面に微細な凹凸を形成したりてしてヘーズを高くすることで、非透視性で透光性の電波吸収体Ａを簡単に得ることができる。更に、不透明の電波吸収体Ａとしたい場合は、誘電体層１、表面被覆層４、裏面被覆層５とを形成する合成樹脂やガラスに顔料などの着色剤を添加することによって不透明としたり、或は電波反射体２に光を透過しない金属板などを使用したり、或は抵抗膜３にカーボンなどを添加して不透明にするなどにより、これらのいずれか或は全てを不透明にすることにより、簡単に得ることができる。   In addition, when the radio wave absorber A that does not have transparency but has translucency is used, for example, a light diffusing agent or a filler is added in advance as the dielectric layer 1, the surface coating layer 4, or the back surface coating layer 5. Or by forming fine irregularities on the outer surface of the surface coating layer 4 or the back surface coating layer 5 to increase the haze, thereby making the non-transparent and translucent radio wave absorber A Can be easily obtained. Furthermore, when it is desired to make the opaque wave absorber A, it is made opaque by adding a colorant such as a pigment to the synthetic resin or glass forming the dielectric layer 1, the surface coating layer 4, and the back surface coating layer 5, Or by using a metal plate that does not transmit light to the radio wave reflector 2 or by making the resistive film 3 opaque by adding carbon or the like, making any or all of these opaque. Easy to get.

また、封止層６を形成するものとしてシーリング剤や樹脂塗液の封止剤を用いる場合は、上記の導電膜３を形成した誘電体層１又は表面被覆層４の四周の周縁部にシーリング剤若しくは樹脂塗液を塗布して誘電体層１と表面被覆層４を重ね、これらの誘電体層１と表面被覆層４の周縁部の隙間をシーリング剤若しくは樹脂塗液で充填した後、これらを硬化して封止層６を形成し、この封止層６で上記周縁部を封止接合する。そして、これを反転させて誘電体層１の反対面に電波反射体２を重ね、接着剤として例えば上記のシーリング剤を電波反射体２の周縁部に塗布して、その上に裏面被覆層５を重ね、シーリング剤を硬化させて電波反射体２と裏面被覆層５を誘電体層１の裏面に接合一体化することにより、電波吸収体Ａを製造する。   Further, when a sealing agent or a resin coating liquid sealing agent is used to form the sealing layer 6, the sealing is performed on the periphery of the four circumferences of the dielectric layer 1 or the surface coating layer 4 on which the conductive film 3 is formed. After applying the agent or resin coating liquid, the dielectric layer 1 and the surface coating layer 4 are overlapped, and the gap between the peripheral portions of the dielectric layer 1 and the surface coating layer 4 is filled with the sealing agent or the resin coating liquid. Is cured to form the sealing layer 6, and the peripheral edge portion is sealed and joined with the sealing layer 6. Then, this is reversed, the radio wave reflector 2 is superimposed on the opposite surface of the dielectric layer 1, and, for example, the sealing agent described above is applied as an adhesive to the periphery of the radio wave reflector 2, and the back surface coating layer 5 is formed thereon. The radio wave absorber A is manufactured by curing the sealing agent and bonding and integrating the radio wave reflector 2 and the back surface coating layer 5 to the back surface of the dielectric layer 1.

この実施形態の透視性を有する電波吸収体Ａのように、抵抗膜３が誘電体層１とその片面側の表面被覆層４との間に設けられ、抵抗膜３の周囲に封止層６が形成されていると、誘電体層１と表面被覆層４と封止層６によって抵抗膜３が完全に包囲され、抵抗膜３の両面及び周囲が確実に封止されて密封状態になり、抵抗膜３と外気中の湿気（水分）との接触が断たれるため、抵抗膜３の表面抵抗率がほぼ一定に保たれる。従って、抵抗膜３の表面抵抗率の変化による電波吸収性能の低下が防止され、長期間に亘って初期の良好な電波吸収性能が維持されるので、耐久性及び信頼性が大幅に向上する。しかも、この実施形態の電波吸収体Ａは、抵抗膜３の中に、カーボンナノチューブが凝集することなく１本ずつ分離した状態で、もしくは、複数本集まって束になったものが１束ずつ分離した状態で、分散して互いに接触しているため、カーボンナノチューブの分散状態が極めて良好で相互の接触頻度が高く、少しの含有量で所定の表面抵抗率を確保できるため透視性が良い抵抗膜３となり、これを用いている電波吸収体Ａは透視性が良好なものとなる。また、屋外で使用しても、表面被覆層４及び裏面被覆層５によって、抵抗膜３や誘電体層１や電波反射体２を紫外線劣化から保護することができる。さらに、合成樹脂製の表面被覆層４及び裏面被覆層５であると、飛来物よる破損を防止できる。   Like the transparent radio wave absorber A of this embodiment, the resistance film 3 is provided between the dielectric layer 1 and the surface coating layer 4 on one side thereof, and the sealing layer 6 is provided around the resistance film 3. Is formed, the resistive film 3 is completely surrounded by the dielectric layer 1, the surface covering layer 4, and the sealing layer 6, and both sides and the periphery of the resistive film 3 are surely sealed and sealed. Since the contact between the resistance film 3 and the moisture (moisture) in the outside air is cut off, the surface resistivity of the resistance film 3 is kept substantially constant. Therefore, the deterioration of the radio wave absorption performance due to the change in the surface resistivity of the resistance film 3 is prevented, and the initial good radio wave absorption performance is maintained over a long period of time, so that the durability and reliability are greatly improved. In addition, the radio wave absorber A of this embodiment is separated in the resistive film 3 in a state where the carbon nanotubes are separated one by one without agglomeration, or a bundle of a plurality of bundles is separated one by one. In this state, the dispersed film is in contact with each other, so that the dispersed state of the carbon nanotubes is extremely good, the mutual contact frequency is high, and a predetermined surface resistivity can be secured with a small content, so that the resistance film has good transparency 3 and the radio wave absorber A using this has good transparency. Even when used outdoors, the front surface coating layer 4 and the back surface coating layer 5 can protect the resistance film 3, the dielectric layer 1, and the radio wave reflector 2 from ultraviolet deterioration. Further, when the surface coating layer 4 and the back surface coating layer 5 are made of synthetic resin, damage due to flying objects can be prevented.

図２は本発明の他の実施形態に係る電波吸収体の断面図である。   FIG. 2 is a cross-sectional view of a radio wave absorber according to another embodiment of the present invention.

この電波吸収体Ｂは、抵抗膜３を合成樹脂フィルム３０のいずれか片面に形成して、この抵抗膜形成フィルム３１を誘電体層１とその片面側（表面側）に配置された表面被覆層４との間に設け、この抵抗膜形成フィルム３１の両面、即ち、抵抗膜３の表面及び合成樹脂フィルム３０の反対面と、抵抗膜形成フィルム３１の周囲に封止層６を形成した点で、前述した図１の透視性を有する電波吸収体Ａと異なっている。   In this radio wave absorber B, a resistive film 3 is formed on one side of a synthetic resin film 30, and this resistive film forming film 31 is disposed on the dielectric layer 1 and on one side (front side) thereof. 4, the sealing layer 6 is formed on both surfaces of the resistance film forming film 31, that is, on the surface of the resistance film 3 and the opposite surface of the synthetic resin film 30, and around the resistance film forming film 31. This is different from the radio wave absorber A having transparency shown in FIG.

この電波吸収体Ｂに使用する抵抗膜形成フィルム３１は、誘電体層１と同様のアクリル系樹脂、オレフィン系樹脂、ポリエステル系樹脂などからなる透視性、好ましくは透明な合成樹脂フィルム３０の片面に抵抗膜３を形成したものであって、この抵抗膜３は前記と同様の３７７Ω／□の表面抵抗率を目標値とする透視性、好ましくは透明な薄膜であり、具体的には３７７±３０Ω／□の表面抵抗率を備えたＩＴＯ等の金属酸化物の蒸着膜や、前記の極細導電繊維を含んだ同様の表面抵抗率を有する塗膜からなるものである。この電波吸収体Ｂでは、抵抗膜３が誘電体層１側となるように抵抗膜形成フィルム３１を誘電体層１と表面被覆層４の間に配設しているが、抵抗膜３が表面被覆層４側となるように配設しても勿論よい。   The resistance film forming film 31 used for the radio wave absorber B is formed on one side of a transparent synthetic resin film 30, which is made of transparent resin, such as acrylic resin, olefin resin, polyester resin, and the like, similar to the dielectric layer 1. A resistive film 3 is formed, and the resistive film 3 is a transparent thin film having a surface resistivity of 377 Ω / □ as a target value as described above, preferably a transparent thin film, specifically 377 ± 30 Ω. It consists of a vapor-deposited film of a metal oxide such as ITO having a surface resistivity of / □ or a coating film having the same surface resistivity containing the above-mentioned ultrafine conductive fiber. In this radio wave absorber B, the resistive film forming film 31 is disposed between the dielectric layer 1 and the surface coating layer 4 so that the resistive film 3 is on the dielectric layer 1 side. Of course, it may be arranged so as to be on the coating layer 4 side.

この電波吸収体Ｂの他の構成は前記の電波吸収体Ａと同様であるので、図２において同一部材に同一符号を付して説明を省略する。   Since the other configuration of the radio wave absorber B is the same as that of the radio wave absorber A, the same members in FIG.

このような電波吸収体Ｂは、例えば次の方法で製造することができる。即ち、封止層６として前記のホットメルトシートの封止剤を使用し、誘電体層１の片面側（表面側）にホットメルトシートと、抵抗膜形成フィルム３１と、ホットメルトシートと、表面被覆層４とをこの順に重ねる。そして、誘電体層１の反対面側に電波反射体２を重ねて、さらに接着剤として例えばホットメルトシートを配置し、その裏面に裏面被覆層５を重ねて、この積層物を上下の艶板で挟みながら加熱し、ホットメルトシートを軟化溶融させて接合一体化すると、透視性を有する電波吸収体Ｂが製造される。   Such a radio wave absorber B can be manufactured, for example, by the following method. That is, the sealing agent for the hot melt sheet is used as the sealing layer 6, and the hot melt sheet, the resistance film forming film 31, the hot melt sheet, the surface are formed on one side (front side) of the dielectric layer 1. The coating layer 4 is overlaid in this order. Then, the radio wave reflector 2 is overlaid on the opposite surface side of the dielectric layer 1, and a hot melt sheet is disposed as an adhesive, and the back surface coating layer 5 is overlaid on the back surface. When the hot melt sheet is softened and melted and joined and integrated with each other, the radio wave absorber B having transparency is manufactured.

斯かる電波吸収体Ｂは、抵抗膜３の表面と周囲が封止層６で封止され、抵抗膜３の裏面が合成樹脂フィルム３０と封止層６で二重に封止されて密閉状態となっているため、抵抗膜３と外気中の水分との接触が断たれて抵抗膜３の表面抵抗率がほぼ一定に保たれる。従って、抵抗膜３の表面抵抗率の変化による電波吸収性能の低下が防止され、長期間に亘って初期の良好な電波吸収性能が維持されるので、耐久性及び信頼性が大幅に向上する。特に、この電波吸収体Ｂのように抵抗膜形成フィルム３１の両面と周囲が封止層６で覆われていると、周囲の封止層６にクラック等が生じて、万一、水分を含んだ外気が周囲の封止層６から侵入するようなことがあったとしても、抵抗膜形成フィルム３１の両面を覆う封止層６によってそれ以上内部に浸透することが阻止され、抵抗膜３と外気中の水分との接触が断たれた状態を維持するので、耐久性及び信頼性が一層向上することになる。また、抵抗膜形成フィルム３１の表裏面が封止層６を介して表面被覆層４と誘電体層１で被覆されているので、それらの界面が互いに密着して光散乱が少なくなるために透視性に優れ且つ光線透過率が向上する利点もある。   In such a radio wave absorber B, the surface and the periphery of the resistance film 3 are sealed with the sealing layer 6, and the back surface of the resistance film 3 is double sealed with the synthetic resin film 30 and the sealing layer 6 to be sealed. Therefore, the contact between the resistance film 3 and the moisture in the outside air is cut off, and the surface resistivity of the resistance film 3 is kept almost constant. Therefore, the deterioration of the radio wave absorption performance due to the change in the surface resistivity of the resistance film 3 is prevented, and the initial good radio wave absorption performance is maintained over a long period of time, so that the durability and reliability are greatly improved. In particular, when both sides and the periphery of the resistance film forming film 31 are covered with the sealing layer 6 as in the case of the radio wave absorber B, cracks or the like are generated in the surrounding sealing layer 6, and it should contain moisture. Even if outside air may invade from the surrounding sealing layer 6, the sealing layer 6 covering both surfaces of the resistance film forming film 31 is prevented from penetrating further inside, and the resistance film 3 and Since the state in which contact with moisture in the outside air is cut off is maintained, durability and reliability are further improved. Further, since the front and back surfaces of the resistance film forming film 31 are covered with the surface coating layer 4 and the dielectric layer 1 through the sealing layer 6, the interfaces between them are in close contact with each other, and light scattering is reduced. There is also an advantage that the light transmittance is improved and the light transmittance is improved.

なお、図２に示す実施形態の透視性電波吸収体Ｂでは、抵抗膜形成フィルム３１の周囲と両面を封止層６で封止しているが、抵抗膜形成フィルム３１の周囲と抵抗膜３の表面を封止層６で封止する構成としてもよい。このような構成の透視性電波吸収体も、抵抗膜３の表面と周囲が封止層６で封止されると共に、抵抗膜３の裏面が合成樹脂フィルム３０で封止されて密封状態となるため、抵抗膜３と外気中の水分との接触が断たれて表面抵抗率がほぼ一定に保たれる。   In the transparent radio wave absorber B of the embodiment shown in FIG. 2, the periphery and both surfaces of the resistance film forming film 31 are sealed with the sealing layer 6, but the periphery of the resistance film forming film 31 and the resistance film 3. The surface may be sealed with the sealing layer 6. The transparent radio wave absorber having such a configuration is also sealed by sealing the surface and the periphery of the resistance film 3 with the sealing layer 6 and the back surface of the resistance film 3 with the synthetic resin film 30. Therefore, the contact between the resistance film 3 and the moisture in the outside air is cut off, and the surface resistivity is kept almost constant.

また、図２の電波吸収体Ｂにおいて、抵抗膜形成フィルム３１の両面を覆う封止層６を省略して、誘電体層１と表面被覆層４とで抵抗膜形成フィルム３１を直接挟み、抵抗膜形成フィルム３１の周囲にのみ封止層６を設ける構成としてもよい。このような構成の透視性電波吸収体Ｂも、抵抗膜３の表面が誘電体層１（抵抗膜３が表面被覆層４側となるように抵抗膜形成フィルム３１を設置する場合は表面被覆層４）によって封止され、抵抗膜３の裏面が合成樹脂フィルム３０、更には表面被覆層４によって封止され、抵抗膜３の周囲が封止層６によって封止されて密封状態になっているので、同様に抵抗膜３と外気中の水分との接触が断たれて表面抵抗率がほぼ一定に保たれる。   Further, in the radio wave absorber B of FIG. 2, the sealing layer 6 that covers both surfaces of the resistance film forming film 31 is omitted, and the resistance film forming film 31 is directly sandwiched between the dielectric layer 1 and the surface coating layer 4 to provide resistance. The sealing layer 6 may be provided only around the film forming film 31. The transparent radio wave absorber B having such a configuration also has a surface coating layer when the resistance film 3 is placed on the dielectric layer 1 (the resistance film forming film 31 is placed so that the resistance film 3 is on the surface coating layer 4 side). 4), the back surface of the resistance film 3 is sealed with the synthetic resin film 30 and further with the surface coating layer 4, and the periphery of the resistance film 3 is sealed with the sealing layer 6 to be in a sealed state. Therefore, similarly, the contact between the resistance film 3 and the moisture in the outside air is cut off, and the surface resistivity is kept almost constant.

図３は本発明の更に他の実施形態に係る電波吸収体の断面図である。   FIG. 3 is a cross-sectional view of a radio wave absorber according to still another embodiment of the present invention.

この電波吸収体Ｃは、誘電体層１の片面にその周縁部を除いて抵抗膜３を形成し、この抵抗膜３の表面と周囲に封止層６を形成している点で、前述の図１の透視性を有する電波吸収体Ａと異なっている。その他の構成は前述の透視性電波吸収体Ａと同様であるので、図３において同一部材に同一符号を付して説明を省略する。   In this radio wave absorber C, the resistive film 3 is formed on one surface of the dielectric layer 1 except for the peripheral portion thereof, and the sealing layer 6 is formed on and around the surface of the resistive film 3. This is different from the radio wave absorber A having transparency shown in FIG. Since the other configuration is the same as that of the above-described transparent wave absorber A, the same members in FIG.

斯かる電波吸収体Ｃは、前述の電波吸収体Ａを製造する際に、抵抗膜３と表面被覆層４との間、及び抵抗膜３の周囲にホットメルトシートの封止剤を配置したり、抵抗膜３の表面及び周囲にシーリング剤又は樹脂塗液などの封止剤を塗布或は充填したりして、抵抗膜３の表面及び周囲を封止する封止層６を更に形成することによって製造することができる。   When such a radio wave absorber C is manufactured, a hot-melt sheet sealant is disposed between the resistance film 3 and the surface coating layer 4 and around the resistance film 3 when the radio wave absorber A is manufactured. Further, a sealing layer 6 for sealing the surface and the periphery of the resistance film 3 is further formed by applying or filling a sealing agent such as a sealing agent or a resin coating solution on the surface and the periphery of the resistance film 3. Can be manufactured by.

このような透視性を有する電波吸収体Ｃも、表面被覆層４と封止層６によって抵抗膜３の表面が封止されると共に封止層６により抵抗膜３の周囲が封止され、さらに、誘電体層１によって抵抗膜３の裏面が封止されて密封状態になるため、外気中の水分との接触が断たれ、抵抗膜３の表面抵抗率がほぼ一定に保たれるので、耐久性及び信頼性が向上する。そして、周囲の封止層６にクラック等が生じて、万一、水分を含んだ外気が周囲の封止層６から侵入するようなことがあったとしても、抵抗膜３の表面を覆う封止層６によってそれ以上内部に浸透することが阻止されるので、抵抗膜３の表面抵抗率はほぼ一定に保たれ、初期の電波吸収性能が維持される。また、抵抗膜３の表面が封止層６で被覆されていると、抵抗膜３と表面被覆層４との界面での光散乱が少なくなり透視性及び光線透過率が向上する利点もある。   Also in the radio wave absorber C having such transparency, the surface of the resistance film 3 is sealed by the surface coating layer 4 and the sealing layer 6, and the periphery of the resistance film 3 is sealed by the sealing layer 6. Since the back surface of the resistance film 3 is sealed by the dielectric layer 1, the contact with moisture in the outside air is cut off, and the surface resistivity of the resistance film 3 is kept almost constant. And reliability are improved. Then, even if cracks or the like are generated in the surrounding sealing layer 6 and the outside air containing moisture may enter from the surrounding sealing layer 6, the sealing that covers the surface of the resistance film 3 is performed. Since the stop layer 6 prevents further penetration into the interior, the surface resistivity of the resistance film 3 is kept substantially constant, and the initial radio wave absorption performance is maintained. In addition, when the surface of the resistance film 3 is covered with the sealing layer 6, there is an advantage that light scattering at the interface between the resistance film 3 and the surface coating layer 4 is reduced and transparency and light transmittance are improved.

この図３に示す実施形態の透視性を有する電波吸収体Ｃでは、誘電体層１の片面に抵抗膜３を形成してその表面と周囲を封止層６で封止しているが、表面被覆層４の誘電体層１との対向面に抵抗膜３を形成してその表面と周囲を封止層６で封止する構成としてもよい。このような構成の透視性電波吸収体も、封止層６によって抵抗膜３の表面と周囲が封止されると共に、表面被覆層４によって抵抗膜３の裏面が封止されて密封状態となるため、同様に抵抗膜３と外気中の水分との接触が断たれて表面抵抗率がほぼ一定に保たれる。   In the radio wave absorber C having transparency according to the embodiment shown in FIG. 3, the resistive film 3 is formed on one surface of the dielectric layer 1 and the surface and the periphery thereof are sealed with the sealing layer 6. A configuration may be adopted in which the resistance film 3 is formed on the surface of the coating layer 4 facing the dielectric layer 1 and the surface and the periphery thereof are sealed with the sealing layer 6. The transparent radio wave absorber having such a configuration is also sealed by sealing the surface and the periphery of the resistance film 3 with the sealing layer 6 and sealing the back surface of the resistance film 3 with the surface coating layer 4. Therefore, similarly, the contact between the resistance film 3 and the moisture in the outside air is cut off, and the surface resistivity is kept almost constant.

図４は本発明の更に他の実施形態に係る電波吸収体の断面図である。   FIG. 4 is a cross-sectional view of a radio wave absorber according to still another embodiment of the present invention.

この電波吸収体Ｄは、誘電体層１の片面側（表面側）全体に抵抗膜３を形成して抵抗膜３の表面を封止層６で封止する点と、電波吸収体の側面全体に亘って形成した封止層６によって抵抗膜３の周囲を封止している点で、前述の図３に示す電波吸収体Ｃと異なっている。電波吸収体Ｄの側面全体を覆う封止層６としては、前述のホットメルトシート、シーリング剤、樹脂塗液などの封止剤が使用されるが、この中でも、電波吸収体Ｄの側面全体に塗布し易いシーリング剤又は樹脂塗液が好ましく用いられる。この電波吸収体Ｄは、側面全体に封止層６を形成するので、表面被覆層４、抵抗膜３の表面を覆う封止層６、抵抗膜３、誘電体層１、電波反射体２、裏面被覆層５を同一の形状及び大きさとして、側面全体が平坦面となるようにしてある。この電波吸収体Ｄの他の構成は、前述の図３の電波吸収体Ｃと同様であるので、図４において同一部材に同一符号を付して説明を省略する。   This radio wave absorber D has a resistance film 3 formed on the entire one side (surface side) of the dielectric layer 1 and the surface of the resistance film 3 is sealed with the sealing layer 6, and the entire side surface of the radio wave absorber. This is different from the above-described radio wave absorber C shown in FIG. 3 in that the periphery of the resistance film 3 is sealed by the sealing layer 6 formed over the entire area. As the sealing layer 6 that covers the entire side surface of the radio wave absorber D, the above-mentioned sealing agent such as a hot melt sheet, a sealing agent, and a resin coating liquid is used. A sealing agent or a resin coating solution that can be easily applied is preferably used. Since this radio wave absorber D forms the sealing layer 6 on the entire side surface, the surface coating layer 4, the sealing layer 6 covering the surface of the resistance film 3, the resistance film 3, the dielectric layer 1, the radio wave reflector 2, The back surface coating layer 5 has the same shape and size, and the entire side surface is flat. Since the other configuration of the radio wave absorber D is the same as that of the radio wave absorber C of FIG. 3 described above, the same members in FIG.

このような透視性を有する電波吸収体Ｄは、前述の電波吸収体Ｃを製造する際に、誘電体層１、電波反射体２、表面被覆層４、裏面被覆層５、抵抗膜３の表面を覆う封止層形成用のホットメルトシートの封止剤をそれぞれ同一の形状及び大きさに揃え、誘電体層１の片面全体に抵抗膜３を形成すると共に、上記の各部材を積層一体化して電波吸収体の本体部分を作製し、その四周の側面全体に前記のシーリング剤等の封止剤を塗布、硬化させ、側面全体を覆う封止層６を形成することによって製造される。   The radio wave absorber D having such transparency has the surface of the dielectric layer 1, the radio wave reflector 2, the surface coating layer 4, the back surface coating layer 5, and the resistance film 3 when the above-described radio wave absorber C is manufactured. The sealing agent for forming the hot-melt sheet for forming the sealing layer is aligned in the same shape and size, and the resistive film 3 is formed on the entire surface of the dielectric layer 1, and the above-mentioned members are laminated and integrated. Thus, the main body portion of the radio wave absorber is manufactured, and the sealing agent such as the sealing agent is applied and cured on the entire side surface of the four circumferences to form the sealing layer 6 covering the entire side surface.

斯かる透視性電波吸収体Ｄも、抵抗膜３の表面と周囲が、該表面を覆う表面被覆層４及び封止層６と、電波吸収体側面の封止層６によって封止され、抵抗膜３の裏面が誘電体層１で封止されて密封状態となっているため、抵抗膜３と外気中の水分との接触が断たれて抵抗膜３の表面抵抗率がほぼ一定に保たれ、初期の電波吸収性能が維持されるので、耐久性及び信頼性が一層向上する。さらに、表面の封止層６により界面が互いに密着して光散乱が少なくなるために透視性に優れ且つ光線透過率が向上する利点もある。また、電波吸収体Ｄの各構成部材は側面の封止層６で接合一体化されるので、各構成部材を接着する必要がなくなり、製造が容易となる。   In such a transparent radio wave absorber D, the surface and the periphery of the resistance film 3 are sealed by the surface coating layer 4 and the sealing layer 6 covering the surface, and the sealing layer 6 on the side surface of the radio wave absorber. 3 is sealed with the dielectric layer 1, and the contact between the resistance film 3 and the moisture in the outside air is cut off, and the surface resistivity of the resistance film 3 is kept substantially constant. Since the initial radio wave absorption performance is maintained, durability and reliability are further improved. Furthermore, since the interfaces are closely adhered to each other by the sealing layer 6 on the surface and light scattering is reduced, there is an advantage that the transparency is excellent and the light transmittance is improved. Further, since the constituent members of the radio wave absorber D are joined and integrated by the side sealing layer 6, it is not necessary to bond the constituent members, and the manufacture is facilitated.

なお、図４の電波吸収体Ｄでは、誘電体層１の片面（表面）全体に抵抗膜３を形成してその表面を封止層６で被覆しているが、表面被覆層４の誘電体層１との対向面全体に抵抗膜３を形成してその表面を封止層６で被覆する構成としてもよい。このような構成の電波吸収体も、抵抗膜３が封止層６と表面被覆層４で封止されて密封状態となるため、同様に抵抗膜３と外気中の水分との接触が断たれて表面抵抗値がほぼ一定に保たれる。
なお、抵抗膜３の表面を封止層６で封止する必要は必ずしもないが、透視性を向上させる点からは封止することが好ましい。 In the radio wave absorber D of FIG. 4, the resistive film 3 is formed on the entire surface (surface) of the dielectric layer 1 and the surface thereof is covered with the sealing layer 6. It is good also as a structure which forms the resistance film 3 in the whole opposing surface with the layer 1, and coat | covers the surface with the sealing layer 6. FIG. Also in the radio wave absorber having such a configuration, since the resistance film 3 is sealed with the sealing layer 6 and the surface coating layer 4, the contact between the resistance film 3 and moisture in the outside air is similarly cut off. Therefore, the surface resistance value is kept almost constant.
Although it is not always necessary to seal the surface of the resistance film 3 with the sealing layer 6, it is preferable to seal from the viewpoint of improving the transparency.

図５は本発明の更に他の実施形態に係る電波吸収体の断面図である。   FIG. 5 is a cross-sectional view of a radio wave absorber according to still another embodiment of the present invention.

この電波吸収体Ｅは、誘電体層１の大きさより小さな抵抗膜形成フィルム３１を、抵抗膜３が表面被覆層４側となるように誘電体層１と表面被覆層４との間に介在させ、この抵抗膜形成フィルム３１の表面と周囲（誘電体層１の周縁部表面）に封止層６を形成している点で、前述の図４に示す透視性電波吸収体Ｄと異なっている。その他の構成は透視性電波吸収体Ｄと同様であるので、図５において同一部材に同一符号を付して説明を省略する。   In this radio wave absorber E, a resistance film forming film 31 smaller than the size of the dielectric layer 1 is interposed between the dielectric layer 1 and the surface coating layer 4 so that the resistance film 3 is on the surface coating layer 4 side. 4 is different from the transparent radio wave absorber D shown in FIG. 4 in that the sealing layer 6 is formed on the surface and the periphery of the resistance film forming film 31 (the peripheral surface of the dielectric layer 1). . Since the other configuration is the same as that of the transparent radio wave absorber D, the same members in FIG.

このような透視性を有する電波吸収体Ｅは、前記の電波吸収体Ｄを製造する際に、誘電体層１の片面に抵抗膜３を形成することなく、予め作製していた抵抗膜形成フィルム３１を誘電体層１の重ね合せるように変更するだけで、同様に製造することができる。   The radio wave absorber E having such transparency has a resistance film-forming film produced in advance without forming the resistance film 3 on one surface of the dielectric layer 1 when the radio wave absorber D is manufactured. It can be manufactured in the same manner simply by changing 31 so that the dielectric layer 1 is superposed.

斯かる透視性を有する電波吸収体Ｅも、前述の電波吸収体Ｄと同様の作用効果を奏するが、抵抗膜形成フィルム３１の周囲がその周縁部に形成された封止層６と電波吸収体の側面全体に形成された封止層６によって二重に封止されているため、クラック等が発生することがあってもクラックが抵抗膜３まで達することが皆無に等しく、水分を含んだ外気の侵入が一層確実に阻止されるので、耐久性及び信頼性がより一層向上する。   The radio wave absorber E having such transparency has the same effects as the radio wave absorber D described above, but the sealing layer 6 and the radio wave absorber in which the periphery of the resistance film forming film 31 is formed at the peripheral edge thereof. Since the sealing layer 6 formed on the entire side surface of the substrate is double-sealed, even if a crack or the like is generated, the crack does not reach the resistance film 3 at all. As a result, the durability and reliability are further improved.

なお、図５の電波吸収体Ｅでは、誘電体層１の片面側（表面側）に抵抗膜形成フィルム３１を重ね合せて封止層６を設けたが、表面被覆層４の下面に抵抗膜形成フィルム３１のフィルムが重なるように重ね合せ、抵抗膜３と誘電体層１との間に封止層６を形成してもよい。このような構成の電波吸収体も、抵抗膜３が合成樹脂フィルム３０と表面被覆層４で封止されて密封状態となるため、同様に抵抗膜３と外気中の水分との接触が断たれて表面抵抗値がほぼ一定に保たれる。また、表面の封止層６は必ずしも必要ではなく、省略することもできる。   In the radio wave absorber E of FIG. 5, the sealing layer 6 is provided by superimposing the resistance film forming film 31 on one side (front side) of the dielectric layer 1, but the resistance film is provided on the lower surface of the surface coating layer 4. The sealing film 6 may be formed between the resistive film 3 and the dielectric layer 1 by overlapping the film of the forming film 31 so as to overlap each other. Also in the radio wave absorber having such a configuration, since the resistance film 3 is sealed with the synthetic resin film 30 and the surface coating layer 4, the contact between the resistance film 3 and moisture in the outside air is similarly cut off. Therefore, the surface resistance value is kept almost constant. Further, the sealing layer 6 on the surface is not always necessary and can be omitted.

図６は本発明の更に他の実施形態に係る電波吸収体の断面図である。   FIG. 6 is a cross-sectional view of a radio wave absorber according to still another embodiment of the present invention.

この電波吸収体Ｆは、誘電体層１の片面に形成した抵抗膜３を覆う封止層を省略し、誘電体層１の裏面の電波反射体２に接着剤層７を介して裏面被覆層５を積層一体化した点で、前述の図４に示す透視性電波吸収体Ｄと異なっている。接着剤層７としては、前記の封止層形成用のホットメルトシートやシーリング剤や樹脂塗液などの封止剤が使用されるが、透視性又は透明な公知の接着剤、或は透視性の両面粘着テープなども使用可能である。この電波吸収体Ｆの他の構成は前述の電波吸収体Ｄと同様であるので、図６において同一部材に同一符号を付して説明を省略する。   In this radio wave absorber F, a sealing layer covering the resistance film 3 formed on one surface of the dielectric layer 1 is omitted, and the back surface coating layer is disposed on the radio wave reflector 2 on the back surface of the dielectric layer 1 via the adhesive layer 7. 5 is different from the transparent radio wave absorber D shown in FIG. As the adhesive layer 7, a sealing agent such as the above-mentioned hot-melt sheet for forming a sealing layer, a sealing agent, or a resin coating solution is used. However, a known adhesive that is transparent or transparent, or transparent A double-sided adhesive tape can also be used. Since the other configuration of the radio wave absorber F is the same as that of the radio wave absorber D described above, the same members are denoted by the same reference numerals in FIG.

このような透視性を有する電波吸収体Ｆは、前記の電波吸収体Ｄを製造する際に、誘電体層１の片面全体に形成した抵抗膜３の表面に封止層形成用のホットメルトシートを重ねることなく、電波反射体２の表面（下側表面）に接着剤層７となるホットメルトシートなどを介して裏面被覆層４を重ねるように変更するだけで、同様に製造することができる。なお、抵抗膜３は表面被覆層４に形成して誘電体層１と重ね合せてもよい。   The radio wave absorber F having such transparency has a hot melt sheet for forming a sealing layer on the surface of the resistance film 3 formed on the entire surface of the dielectric layer 1 when the radio wave absorber D is manufactured. It is possible to produce the same in a similar manner by simply changing the back surface coating layer 4 so as to overlap the surface (lower surface) of the radio wave reflector 2 with a hot melt sheet or the like serving as the adhesive layer 7 without overlapping. . The resistance film 3 may be formed on the surface coating layer 4 and overlapped with the dielectric layer 1.

斯かる透視性を有する電波吸収体Ｆも、抵抗膜３の両面が誘電体層１と表面被覆層４で封止されると共に、抵抗膜３の周囲が電波吸収体側面の封止層６で封止されて密封状態になっているため、同様に抵抗膜３と外気中の水分との接触が断たれて表面抵抗率がほぼ一定に保たれる。そして、接着剤層７によって誘電体層１と電波反射体２と裏面被覆層５が接合一体化されているため、これらの接合強度も向上すると共に、接着剤層７により電波反射体２と誘電体層１及び裏面被覆層５とが密着して光散乱が少なくなり、透視性及び光線透過率が向上する。   In such a radio wave absorber F having transparency, both sides of the resistance film 3 are sealed with the dielectric layer 1 and the surface coating layer 4, and the periphery of the resistance film 3 is the sealing layer 6 on the side surface of the radio wave absorber. Since it is sealed and in a sealed state, the contact between the resistance film 3 and the moisture in the outside air is similarly cut off, and the surface resistivity is kept substantially constant. Since the dielectric layer 1, the radio wave reflector 2, and the back surface coating layer 5 are bonded and integrated by the adhesive layer 7, their bonding strength is improved, and the radio wave reflector 2 and the dielectric layer 7 are dielectrically bonded by the adhesive layer 7. The body layer 1 and the back surface coating layer 5 are in close contact with each other, so that light scattering is reduced, and transparency and light transmittance are improved.

なお、上記の接着剤層７は、前述した電波吸収体Ａ〜Ｅや後述する電波吸収体Ｇ〜Ｌにおいても、電波反射体２と裏面被覆膜５との間に設けても勿論よい。さらに、接着剤層７は、誘電体層１と電波反射体２の間、或は、電波反射体２と誘電体層１及び裏面被覆層５との間の両方に設けてもよい。さらに、接着剤層７は、電波反射体２の全面に設ける必要はなくて、その四周周囲に設けたり、線状に設けたりして、電波反射体２が剥離しないようにされていればよい。四周周囲に接着剤層７を設ける場合は、透視性を有さないものを使用しても、電波吸収体は透視性を有するものとすることができる。   The adhesive layer 7 may be provided between the radio wave reflector 2 and the back surface coating film 5 in the radio wave absorbers A to E and the radio wave absorbers G to L described later. Further, the adhesive layer 7 may be provided between the dielectric layer 1 and the radio wave reflector 2 or between both the radio wave reflector 2 and the dielectric layer 1 and the back surface coating layer 5. Furthermore, the adhesive layer 7 does not need to be provided on the entire surface of the radio wave reflector 2, and may be provided around the circumference of the radio wave reflector 2 or in a linear shape so that the radio wave reflector 2 is not peeled off. . In the case where the adhesive layer 7 is provided around the four circumferences, the radio wave absorber can have transparency even if a material that does not have transparency is used.

図７は本発明の更に他の実施形態に係る電波吸収体の断面図である。   FIG. 7 is a cross-sectional view of a radio wave absorber according to still another embodiment of the present invention.

この電波吸収体Ｇは、抵抗膜３と表面被覆層４との間に空間８を形成している点、及び接着剤層を介在させていない点で、前述の図６に示す透視性電波吸収体Ｆと異なっている。空間８は空気層であり、抵抗膜３と表面被覆層４との周囲部分にスペーサ８１を配置して一体化することで容易に形成することができる。該スペーサ８１としては、厚みの厚いホットメルトシートを配置したり、シーリング剤や樹脂塗液を厚く塗布して形成したり、或は、他部材例えば合成樹脂シートやプレートなどを配置したりして、抵抗膜３と表面被覆層４との間を隔てて空間８が形成されている。
この透視性を有する電波吸収体Ｇの他の構成は前述の電波吸収体Ｆと同様であるので、図７において同一部材に同一符号を付して説明を省略する。 This radio wave absorber G has the transparent wave absorption shown in FIG. 6 described above in that a space 8 is formed between the resistance film 3 and the surface coating layer 4 and no adhesive layer is interposed. It is different from the body F. The space 8 is an air layer and can be easily formed by disposing and integrating the spacers 81 around the resistive film 3 and the surface coating layer 4. As the spacer 81, a thick hot melt sheet is disposed, a sealing agent or a resin coating solution is formed thickly, or other members such as a synthetic resin sheet or a plate are disposed. A space 8 is formed with a space between the resistance film 3 and the surface coating layer 4.
Since the other configuration of the radio wave absorber G having transparency is the same as that of the radio wave absorber F described above, the same members are denoted by the same reference numerals in FIG.

この透視性を有する電波吸収体Ｇには、上記の如き空間８が形成されていて、当該空間８内の水分は抵抗膜３に浸透するかもしれないが、当該空間８は狭いので水分の量が少なくて、例え表面抵抗率が変化しても実質的な変化はない。そして、空間８は水分を含む外気から表面被覆層４、誘電体層１、封止層６にて封止してあり、外気の水分が空間８へ、延いては抵抗膜３へ浸透することはない。そのため表面抵抗率の変化を抑制することができる。なお、空間８内に乾燥剤などを内在させて湿気を取り除くこともできる。   In the radio wave absorber G having transparency, the space 8 as described above is formed, and the moisture in the space 8 may permeate the resistance film 3, but the amount of moisture is small because the space 8 is narrow. Even if the surface resistivity changes, there is no substantial change. The space 8 is sealed from the outside air containing moisture by the surface coating layer 4, the dielectric layer 1, and the sealing layer 6, and the moisture of the outside air permeates into the space 8 and eventually into the resistance film 3. There is no. Therefore, the change in surface resistivity can be suppressed. It should be noted that moisture can be removed by making a desiccant or the like in the space 8.

このような透視性を有する電波吸収体Ｇは、前記の図６に示す電波吸収体Ｆを製造する際に、誘電体層１の片面全体に形成した抵抗膜３の表面の周囲にスペーサ８１を配置した後に表面被覆層４を重ね合わせることで、容易に製造することができる。なお、抵抗膜３を表面被覆層４の下面に形成し、この抵抗膜３と誘電体層１との間にスペーサ８１を介在させてもよい。   In the radio wave absorber G having such transparency, when the radio wave absorber F shown in FIG. 6 is manufactured, the spacer 81 is provided around the surface of the resistance film 3 formed on one entire surface of the dielectric layer 1. It can manufacture easily by superimposing the surface coating layer 4 after arrange | positioning. The resistance film 3 may be formed on the lower surface of the surface coating layer 4 and a spacer 81 may be interposed between the resistance film 3 and the dielectric layer 1.

斯かる透視性を有する電波吸収体Ｇも、抵抗膜３の裏面が誘電体層１で封止され、表面が空間８を介して表面被覆層４で封止されると共に、抵抗膜３の周囲が電波吸収体側面の封止層６で封止されて密封状態になっているため、同様に抵抗膜３と外気中の水分との接触が断たれて表面抵抗率がほぼ一定に保たれる。そして、空間８も周囲の封止層６で封止されて外気と絶たれていて、外気中の水分が浸透することがないので、空間８が介在されていても、抵抗膜３の表面抵抗率は一定に保たれる。   The radio wave absorber G having such transparency also has the back surface of the resistance film 3 sealed with the dielectric layer 1 and the surface sealed with the surface coating layer 4 through the space 8, and around the resistance film 3. Is sealed by the sealing layer 6 on the side surface of the radio wave absorber, and similarly, the contact between the resistance film 3 and moisture in the outside air is cut off, and the surface resistivity is kept almost constant. . Since the space 8 is also sealed with the surrounding sealing layer 6 and cut off from the outside air, moisture in the outside air does not permeate, so even if the space 8 is interposed, the surface resistance of the resistance film 3 The rate is kept constant.

図８は本発明の更に他の実施形態に係る電波吸収体の断面図である。   FIG. 8 is a cross-sectional view of a radio wave absorber according to still another embodiment of the present invention.

この電波吸収体Ｈは、誘電体層１の片面側（表面側）の周囲を除く表面に抵抗膜３を形成し、反対面側（裏面側）に電波反射体２を配置し、前記抵抗膜３の表面及び周囲を封止層６で封止したものである。
その他の電波吸収体Ｈを構成する誘電体層１、電波反射体２、抵抗膜３は、前記各実施形態で用いられたものが同様に使用されるので、説明を省略する。 In this radio wave absorber H, a resistive film 3 is formed on the surface excluding the periphery of one side (front side) of the dielectric layer 1, and the radio wave reflector 2 is arranged on the opposite side (back side). 3 and the periphery thereof are sealed with a sealing layer 6.
Since the dielectric layer 1, the radio wave reflector 2, and the resistance film 3 constituting the other radio wave absorber H are used in the same manner as in the above embodiments, the description thereof is omitted.

封止層６は、前記各実施形態で用いられるホットメルトシートやシーリング剤や樹脂塗液などの封止剤が用いられて、抵抗膜３の表面はもとより、抵抗膜３の周囲即ち誘電体層１の周囲表面（抵抗膜３が形成されていなくて、且つ抵抗膜３の周囲側端）にまで、ホットメルトシートを配置したり、シーリング剤や樹脂塗液を塗布・硬化させることで、表面及び周囲に封止層６が形成されたものである。   The sealing layer 6 uses a sealing agent such as a hot melt sheet, a sealing agent, or a resin coating solution used in each of the above-described embodiments. By placing a hot melt sheet or applying / curing a sealing agent or a resin coating liquid up to the peripheral surface of 1 (the resistance film 3 is not formed and the peripheral edge of the resistance film 3) And the sealing layer 6 is formed in the circumference | surroundings.

斯かる透視性を有する電波吸収体Ｈも、抵抗膜３の表面と周囲が封止層６によって封止され、抵抗膜３の裏面が誘電体層１で封止されて密封状態となっているため、抵抗膜３と外気中の水分との接触が断たれて抵抗膜３の表面抵抗率がほぼ一定に保たれ、初期の電波吸収性能が維持されるので、耐久性及び信頼性が一層向上する。   The radio wave absorber H having such transparency also has a sealed state in which the surface and the periphery of the resistance film 3 are sealed by the sealing layer 6 and the back surface of the resistance film 3 is sealed by the dielectric layer 1. Therefore, the contact between the resistance film 3 and the moisture in the outside air is cut off, the surface resistivity of the resistance film 3 is kept almost constant, and the initial radio wave absorption performance is maintained, so that durability and reliability are further improved. To do.

なお、この電波吸収体Ｈは、抵抗膜３の表面を封止層６のみで覆っているが、さらにこの封止層６の表面に他部材（例えば、合成樹脂シートなど）を積層したりして、表面の保護、防湿性を高めてもよい。さらに、電波反射体２の裏面にも他部材（例えば、合成樹脂シートなど）を積層して裏面の保護、脱落防止性を向上させてもよい。   The radio wave absorber H covers the surface of the resistance film 3 only with the sealing layer 6, but another member (for example, a synthetic resin sheet or the like) is further laminated on the surface of the sealing layer 6. Thus, surface protection and moisture resistance may be improved. Furthermore, another member (for example, a synthetic resin sheet or the like) may be laminated on the back surface of the radio wave reflector 2 to improve the back surface protection and drop-off prevention properties.

図９は本発明の更に他の実施形態に係る電波吸収体の断面図である。   FIG. 9 is a cross-sectional view of a radio wave absorber according to still another embodiment of the present invention.

この電波吸収体Ｉは、誘電体層１の片面側（表面側）に抵抗膜形成フィルム３１を、その抵抗膜３が誘電体層１側となるように配置し、反対面側（裏面側）に電波反射体２を配置し、電波吸収体の側面全体に封止層６を形成してなるもので、この封止層６で前記抵抗膜３の周囲を封止している。
その他の電波吸収体Ｉを構成する誘電体層１、電波反射体２、抵抗形成フィルム３１、抵抗膜３には、前記各実施形態で用いられたものが同様に使用されるので、説明を省略する。 In this radio wave absorber I, a resistive film forming film 31 is arranged on one side (front side) of the dielectric layer 1 so that the resistive film 3 is on the dielectric layer 1 side, and the opposite side (back side). The radio wave reflector 2 is disposed on the side surface of the radio wave absorber, and the sealing layer 6 is formed on the entire side surface of the radio wave absorber. The sealing layer 6 seals the periphery of the resistance film 3.
The dielectric layer 1, the radio wave reflector 2, the resistance forming film 31, and the resistance film 3 that constitute the other wave absorber I are the same as those used in the above-described embodiments, and thus description thereof is omitted. To do.

この電波吸収体Ｉは、例えば、誘電体層１の片面側に、予め形成された抵抗膜形成フィルム３１を、その抵抗膜３が誘電体層１側となるように配置すると共に、誘電体層１の反対面側に電波反射体２を配置し、これらの重ね合せ体の側面にホットメルトシート封止剤を融着させるか、或はシーリング剤や樹脂塗液などの封止剤を塗布、乾燥させることで封止層６を形成することで、製造することができる。   In this radio wave absorber I, for example, a resistive film forming film 31 formed in advance is arranged on one side of the dielectric layer 1 so that the resistive film 3 is on the dielectric layer 1 side, and the dielectric layer The radio wave reflector 2 is disposed on the opposite side of 1 and a hot-melt sheet sealant is fused to the side surfaces of these superposed bodies, or a sealant such as a sealing agent or a resin coating solution is applied. It can manufacture by forming the sealing layer 6 by making it dry.

斯かる透視性を有する電波吸収体Ｉも、抵抗膜３の表面は合成樹脂フィルム３０で封止され、その周囲も封止層６によって封止され、抵抗膜３の裏面も誘電体層１で封止されて密封状態となっているため、抵抗膜３と外気中の水分との接触が断たれて抵抗膜３の表面抵抗率がほぼ一定に保たれ、初期の電波吸収性能が維持されるので、耐久性及び信頼性が一層向上する。   Also in the radio wave absorber I having such transparency, the surface of the resistance film 3 is sealed with the synthetic resin film 30, the periphery thereof is also sealed with the sealing layer 6, and the back surface of the resistance film 3 is also covered with the dielectric layer 1. Since it is sealed and sealed, the contact between the resistance film 3 and moisture in the outside air is cut off, the surface resistivity of the resistance film 3 is kept substantially constant, and the initial radio wave absorption performance is maintained. Therefore, durability and reliability are further improved.

なお、この電波吸収体Ｉも、前記電波吸収体Ｈと同様に、合成樹脂フィルム３０の表面及び電波反射体２の裏面に他部材を積層して表裏両面の保護などを行わせても良い。   Similarly to the radio wave absorber H, the radio wave absorber I may be provided with other members laminated on the surface of the synthetic resin film 30 and the back surface of the radio wave reflector 2 to protect the front and back surfaces.

図１０は本発明の更に他の実施形態に係る電波吸収体の断面図である。   FIG. 10 is a cross-sectional view of a radio wave absorber according to still another embodiment of the present invention.

この電波吸収体Ｊは、誘電体層１の片面側（表面側）に抵抗膜３と他の誘電体層１１と抵抗膜３と表面被覆層４とをこの順で配置し、反対面側（裏面側）に電波反射体２と裏面被覆層５とを配置し、電波吸収体の側面全体に亘って形成した封止層６によって抵抗膜３の周囲を封止してなるものである。
この電波吸収体Ｊは、抵抗膜３を誘電体層１１を介して２層構造とされている点で、前記実施形態の各電波吸収体とは異なっている。誘電体層１１は誘電体層１と同様の樹脂やガラスよりなり、その厚さを０．１〜５ｍｍ程度のものが使用される。その他の電波吸収体Ｊを構成する誘電体層１、電波反射体２、抵抗膜３、表面被覆層４には、前記各実施形態で用いられたものが同様に使用されるので、説明を省略する。 In this radio wave absorber J, a resistive film 3, another dielectric layer 11, a resistive film 3 and a surface covering layer 4 are arranged in this order on one side (front side) of the dielectric layer 1, and the opposite side ( The radio wave reflector 2 and the back surface coating layer 5 are disposed on the back surface side, and the periphery of the resistance film 3 is sealed with a sealing layer 6 formed over the entire side surface of the radio wave absorber.
The radio wave absorber J is different from the radio wave absorbers of the above-described embodiment in that the resistance film 3 has a two-layer structure with a dielectric layer 11 interposed therebetween. The dielectric layer 11 is made of the same resin or glass as the dielectric layer 1 and has a thickness of about 0.1 to 5 mm. Since the dielectric layer 1, the radio wave reflector 2, the resistance film 3, and the surface coating layer 4 constituting the other radio wave absorbers J are used in the same manner, the description thereof is omitted. To do.

このような透視性を有する電波吸収体Ｊは、誘電体層１の表面に予め抵抗膜３を形成し、また表面被覆層４の裏面に抵抗膜３を形成しておき、抵抗膜付き誘電体層１と誘電体層１１と抵抗膜付き表面被覆層４とを積層することで容易に製造できる。また、誘電体層１１の表裏両面に抵抗膜３、３を形成しておき、誘電体層１と抵抗膜付き誘電体層１１と表面被覆層４とを積層することによっても容易に製造できる。   In the radio wave absorber J having such transparency, the resistive film 3 is formed in advance on the surface of the dielectric layer 1, and the resistive film 3 is formed on the back surface of the surface coating layer 4. It can be easily manufactured by laminating the layer 1, the dielectric layer 11, and the surface coating layer 4 with a resistive film. Further, it can be easily manufactured by forming the resistance films 3 and 3 on both the front and back surfaces of the dielectric layer 11 and laminating the dielectric layer 1, the dielectric layer 11 with a resistance film, and the surface coating layer 4.

斯かる透視性を有する電波吸収体Ｊは、抵抗膜３の表面は誘電体層１１或は表面被覆層４により封止され、抵抗膜３の裏面も誘電体層１１或は誘電体層１で封止され、その周囲も封止層６によって封止されて密封状態となっているため、抵抗膜３、３と外気中の水分との接触が断たれて抵抗膜３、３の表面抵抗率がほぼ一定に保たれ、初期の電波吸収性能が維持されるので、耐久性及び信頼性が一層向上する。
更に、２層の抵抗膜３、３により、長期使用中に一方の抵抗膜３に万一不都合が生じて表面抵抗率が３７７±３０Ω／□の範囲を超えたとしても、他方の抵抗膜３により表面抵抗率を上記範囲を維持できるので、この電波吸収体Ｊの電波吸収性能を長期間に渡って保つことができる。
さらに、２層の抵抗膜３、３により電波吸収性能（リターンロス）が発現する周波数帯域を広げることができる。
この電波吸収体Ｊにおいては、抵抗膜３を２層としたために透明性に若干劣り全光線透過率が３０％以上の範囲となるが、ヘーズが１０％以下の透視性を有する電波吸収体Ｊとなる。 In the radio wave absorber J having such transparency, the surface of the resistance film 3 is sealed with the dielectric layer 11 or the surface coating layer 4, and the back surface of the resistance film 3 is also the dielectric layer 11 or the dielectric layer 1. Since the sealing is performed and the periphery thereof is also sealed with the sealing layer 6, the contact between the resistance films 3 and 3 and the moisture in the outside air is cut off, and the surface resistivity of the resistance films 3 and 3 is reduced. Is kept almost constant and the initial radio wave absorption performance is maintained, so that durability and reliability are further improved.
Further, even if the two-layer resistance films 3 and 3 cause inconvenience in one resistance film 3 during long-term use and the surface resistivity exceeds the range of 377 ± 30Ω / □, the other resistance film 3 Since the surface resistivity can be maintained within the above range, the radio wave absorption performance of the radio wave absorber J can be maintained over a long period of time.
Furthermore, the frequency band in which the radio wave absorption performance (return loss) is exhibited can be expanded by the two-layer resistance films 3 and 3.
In this radio wave absorber J, since the resistance film 3 has two layers, the transparency is slightly inferior, and the total light transmittance is in the range of 30% or more. However, the radio wave absorber J having transparency with a haze of 10% or less. It becomes.

なお、図１０においては、抵抗膜３を２層としたが、さらに多数の抵抗膜を設けてもよい。好ましい層数は２〜３層である。
また、他の実施形態である図１〜９、図１１の電波吸収体の各抵抗膜３を複数にできることは言うまでもない。このことで、この電波吸収体Ｊと同様に、電波吸収性能の安定化と電波吸収性能が発現する周波数帯域の拡大の作用効果を奏することとなる。 In FIG. 10, the resistance film 3 has two layers, but a larger number of resistance films may be provided. The preferred number of layers is 2 to 3 layers.
Moreover, it cannot be overemphasized that each resistance film 3 of the electromagnetic wave absorber of FIGS. 1-9 and FIG. 11 which is other embodiment can be made into two or more. As a result, as with the radio wave absorber J, the effects of stabilizing the radio wave absorption performance and expanding the frequency band in which the radio wave absorption performance is manifested are exhibited.

図１１は本発明の更に他の実施形態に係る電波吸収体の断面図である。   FIG. 11 is a cross-sectional view of a radio wave absorber according to still another embodiment of the present invention.

この電波吸収体Ｋは、電波反射体２の両側に誘電体層１、１が設けられ、この誘電体層１、１の電波反射体２との反対面側に抵抗膜３、３がそれぞれ設けられ、更に各抵抗膜３、３の表面に表面被覆層４、４を積層して７層構造にしてなるものである。そして、この７層構造体の周囲の側面全面が封止層６により封止されている。この電波吸収体Ｋは、接着剤層７を介在させていない点を除いて、その他の構成は前述の電波吸収体Ｆと同様であるので、図１１において同一部材に同一符号を付して説明を省略する。   In this radio wave absorber K, dielectric layers 1 and 1 are provided on both sides of the radio wave reflector 2, and resistance films 3 and 3 are provided on the opposite side of the dielectric layer 1 and 1 to the radio wave reflector 2, respectively. Further, the surface coating layers 4 and 4 are laminated on the surfaces of the resistance films 3 and 3 to form a seven-layer structure. The entire side surface around the seven-layer structure is sealed with the sealing layer 6. The radio wave absorber K is the same as the above radio wave absorber F except that the adhesive layer 7 is not interposed. Therefore, the same members are denoted by the same reference numerals in FIG. Is omitted.

このような透視性を有する電波吸収体Ｋは、表面被覆層４と抵抗膜３と誘電体層１と電波反射体２と誘電体層１と抵抗膜３と表面被覆層４とを重ね合せ、必要に応じて一体化し、その後、この重ね合せ構造体の四周周囲側面の全体に、前記のシーリング剤や樹脂塗液等の封止剤を塗布、硬化させて側面全体を覆う封止層６を形成することによって製造される。この際、抵抗膜３は単独で介在させてもよいし、表面被覆層４に形成されて介在してもよいし、或は誘電体層１に形成されて介在してもよい。なお、抵抗膜３として、抵抗膜形成フィルム３１を使用してもよい。   The radio wave absorber K having such transparency has the surface coating layer 4, the resistance film 3, the dielectric layer 1, the radio wave reflector 2, the dielectric layer 1, the resistance film 3, and the surface coating layer 4 superimposed thereon. A sealing layer 6 that covers the entire side surface by applying and curing the sealing agent such as the sealing agent or the resin coating solution on the entire circumference of the four-circumference peripheral side surface of the overlapped structure, after being integrated as necessary. Manufactured by forming. At this time, the resistance film 3 may be interposed alone, may be formed on the surface coating layer 4, or may be formed on the dielectric layer 1. Note that a resistive film forming film 31 may be used as the resistive film 3.

このような電波吸収体Ｋは、両側の表面被覆層４、４側から抵抗膜３、３及び誘電体層１、１を通って入射する電波を中央の電波反射体２で反射して吸収することができ、また、電波反射体２を共用できるので安価な電波吸収体とすることができる。しかし、抵抗膜３を両面に有するために透視性に若干劣り全光線透過率が３０％以上の範囲となるが、ヘーズが１０％以下の透視性を有する電波吸収体Ｋとなる。
斯かる電波吸収体Ｋも、各抵抗膜３、３の両面が誘電体層１と表面被覆膜４で封止されると共に、抵抗膜３の周囲が電波吸収体側面の封止層６で封止されて密封状態になっているため、同様に抵抗膜３と外気中の水分との接触が断たれて表面抵抗率がほぼ一定に保たれる。 Such a radio wave absorber K reflects and absorbs radio waves incident through the resistance films 3 and 3 and the dielectric layers 1 and 1 from the surface coating layers 4 and 4 on both sides by the central radio wave reflector 2. In addition, since the radio wave reflector 2 can be shared, an inexpensive radio wave absorber can be obtained. However, since the resistance film 3 is provided on both sides, the transparency is slightly inferior and the total light transmittance is in the range of 30% or more, but the radio wave absorber K having transparency with a haze of 10% or less is obtained.
In such a wave absorber K, both sides of each of the resistance films 3 and 3 are sealed with the dielectric layer 1 and the surface coating film 4, and the periphery of the resistance film 3 is a sealing layer 6 on the side of the wave absorber. Since it is sealed and in a sealed state, the contact between the resistance film 3 and the moisture in the outside air is similarly cut off, and the surface resistivity is kept substantially constant.

なお、この電波吸収体Ｋのように、他の実施形態である図１〜１０に示す電波吸収体においても、電波反射体２の両側に誘電体層１、１を介して抵抗膜３、３をそれぞれ設け、この抵抗膜３、３の表裏両面と周囲を封止した電波吸収体とすることもできる。この構造とすることで、この電波吸収体Ｋと同様に、両側から入射する電波を中央の電波反射体２で反射して吸収することができる、という作用効果を奏することとなる。   In addition, in the radio wave absorber shown in FIGS. 1 to 10 which is another embodiment like the radio wave absorber K, the resistance films 3 and 3 are disposed on both sides of the radio wave reflector 2 via the dielectric layers 1 and 1. Each of the resistance films 3 and 3 can be provided as a radio wave absorber in which both the front and back surfaces and the periphery are sealed. By adopting this structure, similarly to the radio wave absorber K, there is an effect that radio waves incident from both sides can be reflected and absorbed by the central radio wave reflector 2.

図１２は本発明の更に他の実施形態に係る電波吸収体の断面図である。   FIG. 12 is a cross-sectional view of a radio wave absorber according to still another embodiment of the present invention.

この電波吸収体Ｌは、誘電体層１の裏面の四周周囲端部にのみ接着剤層７を形成して誘電体層１と電波反射体２と裏面被覆層５とを接着一体化した点、及びコ字形の断面形状を有するアルミニウム等の金属製の枠体９を電波吸収体の周囲に取付けている点、この金属製枠体９の電波が入射する側の表面に電波吸収シート９１が貼付されている点で、前述の図６に示す電波吸収体Ｆと異なるのみであり、他の構成は電波吸収体Ｆと同様であるから図１２において同一部材に同一符号を付して説明を省略する。   This radio wave absorber L is formed by forming the adhesive layer 7 only on the four peripheral edges of the back surface of the dielectric layer 1 and bonding and integrating the dielectric layer 1, the radio wave reflector 2 and the back surface coating layer 5; In addition, a metal frame 9 such as aluminum having a U-shaped cross section is attached to the periphery of the radio wave absorber, and a radio wave absorption sheet 91 is attached to the surface of the metal frame 9 on the side where radio waves are incident. 6 is different from the radio wave absorber F shown in FIG. 6 described above, and the other configuration is the same as that of the radio wave absorber F. Therefore, in FIG. To do.

この電波吸収体Ｌに用いられる接着剤層７としては、前記のホットメルトシートやシーリング剤や樹脂塗液などの封止剤の他に、両面テープやウレタン系の接着剤などが好ましく用いられる。また、電波吸収シート９１はフェライトなどの磁性材料を合成ゴムや合成樹脂に添加してシートに成形したものが好ましく用いられる。   As the adhesive layer 7 used for the radio wave absorber L, a double-sided tape, a urethane-based adhesive, or the like is preferably used in addition to the above-described sealing agent such as a hot melt sheet, a sealing agent, and a resin coating solution. In addition, the radio wave absorbing sheet 91 is preferably formed by adding a magnetic material such as ferrite to synthetic rubber or synthetic resin and molding the sheet into a sheet.

この透視性を有する電波吸収体Ｌは、前述した透視性の電波吸収体Ｆと同様の作用効果を奏することに加えて、周囲に金属製の枠体９が取付けられているため、この枠体９によって電波吸収体の周縁部が保護され、高速道路のＥＴＣ料金所などへの取付作業もし易くなる利点がある。しかも、この枠体９によって裏面被覆層５、電波反射体２、誘電体層１、抵抗膜３、表面被覆層４の各部材が確実に一体化されるので、これらが使用中に分離する心配も解消される。さらに、電波吸収シート９１により金属製枠体９に当たる電波も吸収されるので、この枠体９による電波吸収性能の悪化は防止できる。しかし、この電波吸収シート９１は必ずしも必要ではない。   The radio wave absorber L having transparency has the same effect as that of the radio wave absorber F described above, and a metal frame 9 is attached to the periphery thereof. 9 has an advantage that the peripheral portion of the radio wave absorber is protected, and it is easy to carry out the attaching work to an ETC toll booth on a highway. In addition, the frame 9 ensures that the members of the back surface coating layer 5, the radio wave reflector 2, the dielectric layer 1, the resistance film 3, and the surface coating layer 4 are integrated, so that they may be separated during use. Is also resolved. Furthermore, since the radio wave absorbing sheet 91 also absorbs radio waves hitting the metal frame 9, deterioration of the radio wave absorption performance by the frame 9 can be prevented. However, the radio wave absorbing sheet 91 is not always necessary.

図１２においては、電波吸収体として図６のものを用いたが、その他の図１〜図１１に記載の電波吸収体のいずれかが使用され、その周囲に金属製枠体が取付けられた枠付きの電波吸収体とすることができるのは、言うまでもない。   In FIG. 12, the wave absorber shown in FIG. 6 is used. However, any of the other wave absorbers shown in FIGS. 1 to 11 is used, and a frame having a metal frame attached around it. Needless to say, the radio wave absorber can be provided.

次に、本発明の効果を確認するために行った実験について説明する。   Next, an experiment conducted for confirming the effect of the present invention will be described.

［実験１］
溶媒としてのメチルアルコール／水混合物（混合比３：１）中に、極細導電繊維である単層カーボンナノチューブ（文献Ｃｈｍｉｃａｌ Ｐｈｙｓｉｃｓ Ｌｅｔｔｅｒｓ、３２３（２０００）Ｐ５８０−５８５に基づき合成したもの、直径１．３〜１．８μｍ）と分散剤としてのポリアルキレンエチレン−ポリオキシプロピレン共重合体を加えて均一に混合、分散させ、単層カーボンナノチューブを０．００３質量％、分散剤を０．０５質量％含む塗液を調整した。 [Experiment 1]
Single-walled carbon nanotubes, which are ultrafine conductive fibers (synthesized based on the literature Chemical Physics Letters, 323 (2000) P580-585), in a methyl alcohol / water mixture (mixing ratio 3: 1) as a solvent, diameter 1.3 ~ 1.8 μm) and a polyalkyleneethylene-polyoxypropylene copolymer as a dispersant are added and mixed and dispersed uniformly, and 0.003% by mass of single-walled carbon nanotubes and 0.05% by mass of a dispersant are contained. The coating solution was adjusted.

この塗液を、市販の厚さ１００μｍのポリメチルメタクリレートフィルム３０の表面に、単層カーボンナノチューブの目付け量が約９４ｍｇ／ｍ２となるように塗布、乾燥して表面抵抗率が３８５Ω/□の透明な抵抗膜３をポリメチルメタクリレートフィルムの片面に備えた透明な抵抗膜形成フィルム３１（図１５（ａ）（ｂ）参照）を作製した。そして、この抵抗膜形成フィルム３１を１００×１１０ｍｍの大きさに切断し、その相対向する２辺に一対の帯状の銅箔の電極３２（幅５ｍｍ，長さ１５０ｍｍ）を１００ｍｍの辺に沿って導電接着剤で接着して、抵抗膜３の大きさが１００×１００ｍｍの電極付き抵抗膜形成フィルムを作製した。 This coating solution is applied to the surface of a commercially available polymethyl methacrylate film 30 having a thickness of 100 μm so that the amount of single-walled carbon nanotubes is about 94 mg / m 2 and dried to have a surface resistivity of 385Ω / □. A transparent resistance film-forming film 31 (see FIGS. 15A and 15B) having the transparent resistance film 3 provided on one side of a polymethyl methacrylate film was produced. And this resistance film formation film 31 is cut | disconnected to the magnitude | size of 100x110 mm, and a pair of strip | belt-shaped copper foil electrode 32 (width 5mm, length 150mm) is set along the 100mm edge | side to the two opposing sides. A resistive film forming film with an electrode having a size of the resistance film 3 of 100 × 100 mm was prepared by bonding with a conductive adhesive.

図１５（ａ）（ｂ）に示すように、この電極付き抵抗膜形成フィルムの上下両面に、ポリウレタンよりなる１２０ｍｍ角のホットメルトシート６０、６０（厚さ１ｍｍ）を重ね、更にその上下に１３３ｍｍ角のポリカーボネート板４０、５０（厚さ２ｍｍ）を重ねて、これを２００ｍｍ角の艶板で上下から挟み、１２５℃で加熱することにより、ホットメルトシートを軟化溶融させて電極付き抵抗膜形成フィルム３１の周囲及び上下両面をホットメルトシート６０、６０の封止層で封止すると共に、ポリカーボネート板４０、５０で被覆・封止した、実験１の表裏両面と周囲とが封止された抵抗膜を作製した。
この抵抗膜について、抵抗膜の表面抵抗率の経時的変化を室温２３℃、湿度５０％の恒温恒室の室内にて調べた。その結果を図１６に示す。 As shown in FIGS. 15 (a) and 15 (b), 120 mm square hot melt sheets 60 and 60 (thickness 1 mm) made of polyurethane are stacked on the upper and lower surfaces of the resistance film forming film with electrodes, and 133 mm is further formed on the upper and lower sides thereof. Square polycarbonate plates 40 and 50 (thickness 2 mm) are stacked, sandwiched from above and below by a 200 mm square gloss plate, and heated at 125 ° C. to soften and melt the hot melt sheet to form a resistive film with electrode The resistance film in which both the front and back surfaces and the periphery of Experiment 1 were sealed with the sealing layers of the hot melt sheets 60 and 60, and covered and sealed with the polycarbonate plates 40 and 50. Was made.
With respect to this resistance film, the change over time in the surface resistivity of the resistance film was examined in a constant temperature and constant temperature room at 23 ° C. and 50% humidity. The result is shown in FIG.

［実験２］
実験１で調製した塗液を、単層カーボンナノチューブの目付け量が約９４ｍｇ／ｍ２となるように、１００×１１０ｍｍの大きさのポリメチルメタクリレートフィルム（厚さ０．１ｍｍ）の片面に塗布、乾燥して、表面抵抗率が３７５Ω/□の透明な抵抗膜を形成し、この抵抗膜の上面に実験１で使用した銅箔の電極を接着して電極付き抵抗膜形成フィルムを作製した。 [Experiment 2]
The coating liquid prepared in Experiment 1 is applied to one side of a 100 × 110 mm polymethyl methacrylate film (thickness 0.1 mm) so that the basis weight of single-walled carbon nanotubes is about 94 mg / m 2 . The film was dried to form a transparent resistive film having a surface resistivity of 375 Ω / □, and the copper foil electrode used in Experiment 1 was adhered to the upper surface of the resistive film to prepare a resistive film-forming film with an electrode.

この電極付き抵抗膜形成フィルムを、１３３ｍｍ角のポリカーボネート板（厚さ２ｍｍ）の上に市販のセロファンテープで固定した後、電極付き抵抗膜形成フィルムの周りに、高さが１０ｍｍ、一辺の長さが１２０ｍｍの方形枠をセロファンテープで作り、この方形枠で囲まれた電極付き抵抗膜形成フィルムの抵抗膜の上に、シリコーン系のポッティング用液状シーリング剤（ＧＥ東芝シリコーン（株）製のＴＳＥ３０３３）を滴下し、８０℃で３時間硬化させて、電極付き導電膜形成フィルムの周囲と導電膜の上面を厚さ０．２ｍｍの粘着性のあるゴム状のシリコーン系シーリング剤で封止した、表裏両面と周囲とが封止された実験２の抵抗膜を作製した。
この抵抗膜について、実験１と同様に、抵抗膜の表面抵抗率の経時的変化を調べた。その結果を図１６に示す。 After this resistance film forming film with electrodes was fixed on a 133 mm square polycarbonate plate (thickness 2 mm) with a commercially available cellophane tape, the height was 10 mm and the length of one side around the resistance film forming film with electrodes. A 120 mm square frame is made of cellophane tape, and a silicone-based potting liquid sealing agent (GESE Silicone Co., Ltd. TSE3033) is formed on the resistive film of the resistive film forming film with electrodes surrounded by the square frame. The film was cured at 80 ° C. for 3 hours, and the periphery of the conductive film with electrode and the upper surface of the conductive film were sealed with an adhesive rubber-like silicone sealant having a thickness of 0.2 mm. A resistance film of Experiment 2 in which both sides and the periphery were sealed was produced.
With respect to this resistance film, the change over time in the surface resistivity of the resistance film was examined in the same manner as in Experiment 1. The result is shown in FIG.

［比較実験１］
比較のために、実験２で作製した電極付き抵抗膜形成フィルム（表面抵抗率３７５Ω/□）について、実験１と同様に、その抵抗膜の表面抵抗率の経時的変化を調べた。その結果を図１６に示す。 [Comparative Experiment 1]
For comparison, the resistance film-forming film with electrode (surface resistivity 375Ω / □) produced in Experiment 2 was examined for changes in the surface resistivity of the resistive film over time, as in Experiment 1. The result is shown in FIG.

図１６のグラフからわかるように、封止していない比較実験１の抵抗膜は、表面抵抗率が日数の経過にしたがって漸増し、５日経過で３０Ω／□増加し、１１日経過で５０Ω／□増加し、２０日経過で９０Ω／□増加し、２６日経過では１１０Ω／□も増加していていることがわかった。従って、この抵抗膜を用いた電波吸収体であれば、１１日経過後には４２５Ω／□となり、これ以降には電波が吸収され難くなる。これに対して、抵抗膜の表面と周囲をホットメルトシートにて封止した実験１、抵抗膜の表面と周囲をシーリング剤にて封止した実験２の各抵抗膜は、日数が経過しても表面抵抗率が１０Ω／□以下の範囲で増減していて変化が極めて少なく略一定していて、封止により表面抵抗率の変化（増加・減少）が確実に防止できていることがわかった。従って、表面抵抗率が変化しても３６１〜３８５Ω／□の範囲であり、この抵抗膜を用いた電波吸収体は長期間電波吸収機能を発揮することがわかる。   As can be seen from the graph of FIG. 16, the resistance film of Comparative Experiment 1 that was not sealed gradually increased in surface resistivity with the passage of days, increased by 30 Ω / □ after 5 days, and increased by 50 Ω / □ after 11 days. □ increased, increased by 90 Ω / □ after 20 days, and increased by 110 Ω / □ after 26 days. Therefore, in the case of a radio wave absorber using this resistance film, it becomes 425 Ω / □ after 11 days, and the radio wave becomes difficult to be absorbed thereafter. In contrast, each of the resistive films in Experiment 1 in which the surface and the periphery of the resistive film were sealed with a hot melt sheet and in Experiment 2 in which the surface and the periphery of the resistive film were sealed with a sealing agent, the number of days passed. The surface resistivity increased or decreased in the range of 10Ω / □ or less, and the change was extremely small and substantially constant, and it was found that the surface resistivity change (increase / decrease) could be reliably prevented by sealing. . Therefore, even if the surface resistivity changes, it is in the range of 361 to 385 Ω / □, and it can be seen that the radio wave absorber using this resistive film exhibits a radio wave absorbing function for a long period of time.

［実験３］
実験１で調製した塗液を、片面を耐候処理した市販の厚さ２ｍｍのポリカーボネート板の耐候処理を施していない面に、単層カーボンナノチューブの目付け量が約９４ｍｇ／ｍ２となるように塗布、乾燥して、表面抵抗値が３８２Ω/□の透明な抵抗膜を片面に備えた透明な表面被覆層用ポリカーボネート板を作製し、これを縦７０ｍｍ×横８０ｍｍの大きさに切断して、その相対向する２辺（７０ｃｍの各辺）に一対の帯状の銅箔電極（幅５ｍｍ，長さ９０ｍｍ）を導電接着剤で接着することにより、片面に抵抗膜を有する表面被覆層用電極付きポリカーボネート板を得た。 [Experiment 3]
The coating solution prepared in Experiment 1 was applied to the surface of a commercially available polycarbonate plate having a thickness of 2 mm that had been subjected to weathering treatment on one side so that the basis weight of single-walled carbon nanotubes was about 94 mg / m 2. , Dried to produce a transparent surface coating layer polycarbonate plate having a transparent resistance film with a surface resistance value of 382 Ω / □ on one side, cut into a size of 70 mm in length × 80 mm in width, Polycarbonate with electrode for surface coating layer having resistance film on one side by bonding a pair of strip-shaped copper foil electrodes (width 5mm, length 90mm) to two opposite sides (each side of 70cm) with conductive adhesive I got a plate.

この表面被覆層用電極付きポリカーボネート板の抵抗膜側に、誘電体層として市販の厚さ７ｍｍのポリカーボネート板を縦７０ｍｍ×横８０ｍｍの大きさに切断したものを重ねると共に、この誘電体層用ポリカーボネート板の反対側に、電波反射体として市販の導電メッシュを縦７０ｍｍ×横８０ｍｍの大きさに切断したものと、裏面被覆層として耐候処理を施した市販の厚さ２ｍｍのポリカーボネート板を縦７０ｍｍ×横８０ｍｍの大きさに切断したものを重ねて、この積層体の周囲の側面全体を市販のシリコーン系シーリング剤（東レ・ダウコーニング（株）製のＳＥ９６０）を塗布、乾燥して封止層６を形成することで封止し、さらに、アルミニウム製の枠体を四周に取付けて、透視性を備えた電波吸収体を作製した。   A polycarbonate plate having a thickness of 70 mm and a width of 80 mm cut as a dielectric layer is stacked on the resistance film side of the polycarbonate plate with an electrode for the surface coating layer, and the polycarbonate for the dielectric layer. On the opposite side of the plate, a commercially available conductive mesh as a radio wave reflector cut into a size of 70 mm in length and 80 mm in width and a commercially available polycarbonate plate with a thickness of 2 mm subjected to weathering treatment as a back coating layer are 70 mm in length. A layer cut to a size of 80 mm in width is overlapped, and a commercially available silicone sealant (SE960 manufactured by Toray Dow Corning Co., Ltd.) is applied to the entire side surface around the laminate and dried to form a sealing layer 6. In addition, an aluminum frame body was attached to all four sides to produce a radio wave absorber having transparency.

この透視性電波吸収体について、超促進耐候試験機である岩崎電気株式会社製アイ スーパー ＵＶテスター ＳＵＶ−Ｗ１５１を用いて、温度６３℃、湿度５０％で６時間、及び、温度２０℃、湿度９５％で６時間を１サイクルとして繰り返し、抵抗膜３の表面抵抗率の経時的変化を調べた。その結果を図１７に示す。
ただし、抵抗膜は、光によって表面抵抗率が変化する恐れがあるので、この光の影響を除外するために、表面被覆層４及び裏面被覆層５のポリカーボネート板の上にアルミニウムフィルムを重ね合せて光を遮断した。 About this transparent wave absorber, it is 6 hours at a temperature of 63 ° C. and a humidity of 50%, and a temperature of 20 ° C. and a humidity of 95 using an I-super UV tester SUV-W151 manufactured by Iwasaki Electric Co., Ltd. which is a super accelerated weathering tester % Was repeated as one cycle, and the change in the surface resistivity of the resistive film 3 over time was examined. The result is shown in FIG.
However, since the surface resistivity of the resistance film may change due to light, an aluminum film is superimposed on the polycarbonate plate of the surface coating layer 4 and the back surface coating layer 5 in order to eliminate the influence of this light. Blocked the light.

図１７のグラフを見ると、サイクル数が増えても表面抵抗率がほぼ一定しており、経時的な表面抵抗率の増加が確実に防止されていることが分かる。このことから、抵抗膜の表裏にポリカーボネート製表面被覆層とポリカーボネート製誘電層を積層し、さらに誘電体層の下面に導電メッシュ製電波反射体とポリカーボネート製裏面被覆層を積層し、さらに、この積層体の周囲の側面全体をシリコーン系シーリング剤で封止層を形成した本発明の電波吸収体は、抵抗膜の表面抵抗率がほぼ一定しているので、初期の電波吸収性能を維持することがわかる。   It can be seen from the graph of FIG. 17 that the surface resistivity is almost constant even when the number of cycles is increased, and the increase in surface resistivity over time is reliably prevented. Therefore, a polycarbonate surface coating layer and a polycarbonate dielectric layer are laminated on the front and back of the resistance film, and a conductive mesh radio wave reflector and a polycarbonate back coating layer are further laminated on the lower surface of the dielectric layer. The wave absorber of the present invention in which the sealing layer is formed on the entire side surface of the body with a silicone-based sealing agent has a substantially constant surface resistivity of the resistance film, so that the initial wave absorbing performance can be maintained. Recognize.

以上の実験結果から、本発明の電波吸収体は、抵抗膜を水分を含んだ外気から封止することで、抵抗膜の表面抵抗率の変化による電波吸収性能の低下が防止され、長期に亘って初期の良好な電波吸収性能を維持できることが裏付けられる。   From the above experimental results, the radio wave absorber of the present invention prevents the deterioration of radio wave absorption performance due to the change in the surface resistivity of the resistive film by sealing the resistive film from the outside air containing moisture, and for a long time. It is proved that the initial good electromagnetic wave absorption performance can be maintained.

本発明の一実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on one Embodiment of this invention. 本発明の他の実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on other embodiment of this invention. 本発明の更に他の実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on other embodiment of this invention. 本発明の更に他の実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on other embodiment of this invention. 本発明の更に他の実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on other embodiment of this invention. 本発明の更に他の実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on other embodiment of this invention. 本発明の更に他の実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on other embodiment of this invention. 本発明の更に他の実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on other embodiment of this invention. 本発明の更に他の実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on other embodiment of this invention. 本発明の更に他の実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on other embodiment of this invention. 本発明の更に他の実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on other embodiment of this invention. 本発明の更に他の実施形態に係る電波吸収体の断面図である。It is sectional drawing of the electromagnetic wave absorber which concerns on other embodiment of this invention. （ａ）（ｂ）（ｃ）は抵抗膜の部分断面図である。(A) (b) (c) is a fragmentary sectional view of a resistance film. 抵抗膜に含まれるカーボンナノチューブを正面から見た分散状態を示す模式図である。It is a schematic diagram which shows the dispersion state which looked at the carbon nanotube contained in a resistive film from the front. （ａ）は実験用の電極付き抵抗膜形成フィルムの分解側面図であり、（ｂ）は同電極付き抵抗膜形成フィルムの平面図である。(A) is a decomposition | disassembly side view of the resistive film formation film with an electrode for an experiment, (b) is a top view of the resistance film formation film with the electrode. 抵抗膜の表面抵抗率の変化と日数との関係を示すグラフである。It is a graph which shows the relationship between the change of the surface resistivity of a resistive film, and days. 本発明の電波吸収体における抵抗膜の表面抵抗率の変化と超促進耐候試験のサイクル数との関係を示すグラフである。It is a graph which shows the relationship between the change of the surface resistivity of the resistance film in the electromagnetic wave absorber of this invention, and the cycle number of a super accelerated weathering test.

符号の説明Explanation of symbols

１ 誘電体層
２ 電波反射体
３ 抵抗膜
３ａ カーボンナノチューブ
３ｂ バインダー
３０ 合成樹脂フィルム
３１ 抵抗膜形成フィルム
４ 表面被覆層
５ 裏面被覆層
６ 封止層
７ 接着剤層
８ 金属の枠体 DESCRIPTION OF SYMBOLS 1 Dielectric layer 2 Radio wave reflector 3 Resistive film 3a Carbon nanotube 3b Binder 30 Synthetic resin film 31 Resistive film formation film 4 Surface coating layer 5 Back surface coating layer 6 Sealing layer 7 Adhesive layer 8 Metal frame

Claims (12)

抵抗膜を誘電体層の片面側に設けると共に、誘電体層の反対面側に電波反射体を設けた電波吸収体であって、抵抗膜を水分を含む外気から封止したことを特徴とする電波吸収体。   A radio wave absorber in which a resistive film is provided on one side of a dielectric layer and a radio wave reflector is provided on the opposite side of the dielectric layer, wherein the resistive film is sealed from outside air containing moisture Radio wave absorber. 抵抗膜を誘電体層とその片面側に配置された表面被覆層との間に設けると共に、抵抗膜の周囲に封止層を形成して、水分を含む外気から封止したことを特徴とする請求項１に記載の電波吸収体。   The resistive film is provided between the dielectric layer and the surface coating layer disposed on one side thereof, and a sealing layer is formed around the resistive film to seal it from the outside air containing moisture. The radio wave absorber according to claim 1. 抵抗膜を誘電体層の片面に設けると共に、抵抗膜の表面と周囲に封止層を形成して、水分を含む外気から封止したことを特徴とする請求項１に記載の電波吸収体。   2. The radio wave absorber according to claim 1, wherein a resistance film is provided on one surface of the dielectric layer, and a sealing layer is formed on and around the resistance film to seal it from outside air containing moisture. 抵抗膜を誘電体層の片面側に配置された表面被覆層の該誘電体層との対向面に設けると共に、抵抗膜の表面と周囲に封止層を形成して、水分を含む外気から封止したことを特徴とする請求項１に記載の電波吸収体。   The resistance film is provided on the surface of the surface coating layer disposed on one side of the dielectric layer, and is opposed to the dielectric layer, and a sealing layer is formed on the surface of the resistance film and the periphery to seal it from the outside air containing moisture. The radio wave absorber according to claim 1, which is stopped. 抵抗膜を合成樹脂フィルムのいずれか片面に形成し、この抵抗膜形成フィルムの抵抗膜が誘電体層側となるように、誘電体層の片側面側に設けると共に、抵抗膜の周囲に封止層を形成して、水分を含む外気から封止したことを特徴とする請求項１に記載の電波吸収体。   A resistive film is formed on one side of a synthetic resin film, and is provided on one side of the dielectric layer so that the resistive film of the resistive film forming film is on the dielectric layer side, and sealed around the resistive film The radio wave absorber according to claim 1, wherein a layer is formed and sealed from outside air containing moisture. 抵抗膜を合成樹脂フィルムのいずれか片面に形成して誘電体層とその片面側に配置された表面被覆層との間に設けると共に、この抵抗膜形成フィルムの周囲に封止層を形成して、水分を含む外気から封止したことを特徴とする請求項１に記載の電波吸収体。   A resistive film is formed on one side of the synthetic resin film and provided between the dielectric layer and the surface coating layer disposed on the single side, and a sealing layer is formed around the resistive film forming film. The radio wave absorber according to claim 1, which is sealed from outside air containing moisture. 抵抗膜を合成樹脂フィルムのいずれか片面に形成して誘電体層の片面側に設けると共に、この抵抗膜形成フィルムの周囲と両面、又は、抵抗膜形成フィルムの周囲と抵抗膜の表面に封止層を形成して、水分を含む外気から封止したことを特徴とする請求項１に記載の電波吸収体。   A resistive film is formed on one side of the synthetic resin film and provided on one side of the dielectric layer, and sealed around and around the resistive film forming film, or around the resistive film forming film and the surface of the resistive film The radio wave absorber according to claim 1, wherein a layer is formed and sealed from outside air containing moisture. 電波反射体の両側に設けられている誘電体層の電波反射体との反対面側に抵抗膜をそれぞれ設けたことを特徴とする請求項１に記載の電波吸収体。   2. The radio wave absorber according to claim 1, wherein a resistive film is provided on the opposite side of the dielectric layer provided on both sides of the radio wave reflector from the radio wave reflector. 封止層がシリコーン系又はウレタン系の封止剤で形成したものであることを特徴とする請求項２ないし請求項７のいずれかに記載の電波吸収体。   The radio wave absorber according to any one of claims 2 to 7, wherein the sealing layer is formed of a silicone-based or urethane-based sealant. 抵抗膜が極細導電繊維を含んだ膜であって、極細導電繊維が凝集することなく分散して互いに接触していることを特徴とする請求項１ないし請求項８のいずれかに記載の電波吸収体。   9. The radio wave absorption according to claim 1, wherein the resistance film is a film containing ultrafine conductive fibers, and the fine conductive fibers are dispersed without contacting each other and are in contact with each other. body. 表面被覆層が紫外線吸収剤を含んだ合成樹脂板であることを特徴とする請求項２、請求項４又は請求項６に記載の電波吸収体。   The radio wave absorber according to claim 2, 4 or 6, wherein the surface coating layer is a synthetic resin plate containing an ultraviolet absorber. 抵抗膜、誘電体層、表面被覆層、封止層のいずれもが透視性を有すると共に電波反射体が光を透過して、透視性を有する電波吸収体となしたことを特徴とする請求項１ないし請求項１０のいずれかに記載の電波吸収体。   The resistive film, the dielectric layer, the surface coating layer, and the sealing layer are all transparent, and the radio wave reflector transmits light to form a radio wave absorber having transparency. The radio wave absorber according to any one of claims 1 to 10.
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