WO2021060353A1 - λ/4 WAVE ABSORBER - Google Patents

λ/4 WAVE ABSORBER Download PDF

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Publication number
WO2021060353A1
WO2021060353A1 PCT/JP2020/035970 JP2020035970W WO2021060353A1 WO 2021060353 A1 WO2021060353 A1 WO 2021060353A1 JP 2020035970 W JP2020035970 W JP 2020035970W WO 2021060353 A1 WO2021060353 A1 WO 2021060353A1
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WO
WIPO (PCT)
Prior art keywords
radio wave
thickness
layer
wave absorber
dielectric layer
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PCT/JP2020/035970
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French (fr)
Japanese (ja)
Inventor
幸子 中尾
勝紀 武藤
哲郎 澤田石
Original Assignee
積水化学工業株式会社
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Application filed by 積水化学工業株式会社 filed Critical 積水化学工業株式会社
Priority to JP2020564511A priority Critical patent/JPWO2021060353A1/ja
Publication of WO2021060353A1 publication Critical patent/WO2021060353A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/025—Electric or magnetic properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields

Definitions

  • the present invention relates to a ⁇ / 4 type radio wave absorber and the like.
  • Patent Document 1 discloses an electromagnetic wave absorber having a bandwidth of 2 GHz or more in a frequency band having an electromagnetic wave absorption amount of 20 dB or more in a frequency band of 60 to 90 GHz.
  • the radio wave absorption characteristics have been controlled by making the thickness of the dielectric layer as uniform as possible.
  • An object of the present invention is to provide a new technique for controlling radio wave absorption characteristics in a ⁇ / 4 type radio wave absorber.
  • the present inventor has found that even if a step is provided in the dielectric layer, good radio wave absorption characteristics can be exhibited in a target wavelength range.
  • the radio wave absorption peak position when the step is provided almost coincides with the radio wave absorption peak position calculated by regarding the area average thickness of the dielectric layer having the step as the thickness of the dielectric layer. That is, it was found that the radio wave absorption peak position when the step is provided can be controlled based on the respective thicknesses of the thick region and the thin region of the dielectric layer and their area ratios. In the past, it was required to make the thickness of the dielectric layer as uniform as possible, and this result was surprising. The present inventor has completed the present invention as a result of further research based on these findings.
  • the present invention includes the following aspects.
  • a ⁇ / 4 type radio wave absorber including a resistance film, a dielectric layer, and a reflective layer, wherein the dielectric layer has two or more regions having a thickness difference of 15 ⁇ m or more.
  • Item 2 The ⁇ / 4 type radio wave absorber according to Item 1, wherein the difference in thickness is 350 ⁇ m or less.
  • Item 3 The ⁇ / 4 type radio wave absorber according to Item 1 or 2, wherein the thickness of each of the two or more regions is 80 to 120% with respect to the area average thickness of the dielectric layer of 100%.
  • Item 4. The ⁇ / 4 type radio wave absorber according to any one of Items 1 to 3, wherein the area average thickness of the dielectric layer is 100 to 800 ⁇ m.
  • Item 5 The ⁇ / 4 type radio wave absorber according to any one of Items 1 to 4, wherein the radio wave absorption amount at 60 to 90 GHz is 15 dB or more.
  • a ⁇ / 4 type radio wave absorber containing a resistance film, a dielectric layer, and a reflection layer, and having an Rz of 7.5 ⁇ m or more on at least one of the resistance film layer side surface and the reflection layer side surface surface.
  • a ⁇ / 4 type radio wave absorber that includes a resistance film, a dielectric layer, and a reflective layer, and has a thickness difference of 15 ⁇ m or more on the outermost surface.
  • Item 7 A molded product with a radio wave absorber, comprising the molded product and the ⁇ / 4 type radio wave absorber according to any one of Items 1 to 5 attached to the molded product.
  • Item 8. A molded product with a radio wave absorber, which is a millimeter-wave radar.
  • a ⁇ / 4 type radio wave absorber member including a resistance film and a dielectric layer, wherein the dielectric layer has two or more regions having a thickness difference of 25 ⁇ m or more.
  • the radio wave absorption peak position when the dielectric layer is provided with a step has a step based on the knowledge that the radio wave absorption peak position can be controlled based on the respective thicknesses of the thick region and the thin region of the dielectric layer and their area ratios. It is possible to provide a ⁇ / 4 type radio wave absorber including a dielectric layer, and further, a ⁇ / 4 type radio wave absorber having a step formed following the step on the surface.
  • a schematic cross-sectional view of an example of the ⁇ / 4 type radio wave absorber of the present invention is shown.
  • a schematic cross-sectional view of an example of the ⁇ / 4 type radio wave absorber of the present invention is shown.
  • a top view (A) and a schematic cross-sectional view (B) of an example of the ⁇ / 4 type radio wave absorber of the present invention are shown.
  • the gray part shows the convex part and the white part shows the concave part.
  • the top view of an example of the ⁇ / 4 type radio wave absorber of this invention is shown.
  • the gray part shows the convex part and the white part shows the concave part.
  • a schematic cross-sectional view of an example of the ⁇ / 4 type radio wave absorber member of the present invention is shown.
  • a schematic cross-sectional view of an example of a molded product with a radio wave absorber of the present invention is shown.
  • the present invention includes a resistance film, a dielectric layer, and a reflective layer, and the dielectric layer has two or more regions having a thickness difference of 15 ⁇ m or more.
  • ⁇ / 4 type radio wave absorber in the present specification, it may be referred to as “ ⁇ / 4 type radio wave absorber of the present invention”. This will be described below.
  • the resistance film is not particularly limited as long as it includes a layer that can function as a resistance layer in the radio wave absorber.
  • the resistance value of the resistance film is not particularly limited.
  • the resistance value (sheet resistance) of the resistance film is, for example, 100 to 800 ⁇ / ⁇ . Within this range, it is more preferably 150 to 750 ⁇ / ⁇ , still more preferably 200 to 600 ⁇ / ⁇ .
  • the resistance value of the resistance film can be measured by the 4-terminal method using a surface resistance meter (MITSUBISHI CHEMICAL ANALYTECH, trade name "Loresta-EP”).
  • the resistance value is determined by the eddy current method using a non-contact resistance tester (product name "EC-80P, manufactured by Napson, or an equivalent product)" when a support or the like described later is laminated and the resistance film cannot be measured directly. Therefore, it is possible to measure from the surface opposite to the resistance film of the support.
  • the thickness of the resistance film is not particularly limited as long as it has a resistance value that can satisfy the characteristics of the present invention.
  • the thickness of the resistance film is, for example, 1 nm or more and 200 nm or less, preferably 2 nm or more and 100 nm or less, and more preferably 2 nm or more and 50 nm or less.
  • the layer structure of the resistance film is not particularly limited.
  • the resistance film may be composed of a single layer of one type, or may be a combination of a plurality of layers of two or more types.
  • the resistance value of the resistance layer is not particularly limited as long as it can satisfy the characteristics of the present invention.
  • the resistance value of the resistance layer is, for example, 100 to 800 ⁇ / ⁇ . Within this range, it is more preferably 150 to 750 ⁇ / ⁇ , still more preferably 200 to 600 ⁇ / ⁇ .
  • the thickness of the resistance layer is not particularly limited as long as it has a resistance value that can satisfy the characteristics of the present invention.
  • the thickness of the resistance layer is, for example, 1 nm or more and 200 nm or less, preferably 2 nm or more and 100 nm or less, and more preferably 2 nm or more and 50 nm or less.
  • the layer structure of the resistance layer is not particularly limited.
  • the resistance layer may be composed of one type of resistance layer alone, or may be a combination of a plurality of types of resistance layers of two or more types.
  • Indium oxide-containing resistance layer examples include a resistance layer containing a resistance layer material such as indium oxide.
  • the resistance layer material preferably contains a material obtained by doping indium oxide with another material (dopant).
  • dopant another material
  • Other materials are not particularly limited, and examples thereof include tin oxide and zinc oxide, and mixtures thereof.
  • indium oxide preferably, indium (III) oxide (In 2 O 3 ) doped with tin (IV) (SnO 2 ) (indium tin oxide) (tin-).
  • ITO indium oxide
  • the SnO 2 content in ITO is preferably 1 to 40% by weight, because the amorphous structure is extremely stable and the fluctuation of the sheet resistance of the resistance layer can be suppressed even in a high temperature and high humidity environment. It is preferably 2 to 35% by weight.
  • the content of the resistance layer material in the resistance layer is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and usually less than 100% by mass. is there.
  • Molybdenum-containing resistance layer As the resistance layer, a resistance layer containing molybdenum is preferably used from the viewpoint of durability and easy adjustment of sheet resistance.
  • the lower limit of the molybdenum content is not particularly limited, but from the viewpoint of further enhancing durability, 5% by weight is preferable, 7% by weight is more preferable, 9% by weight is further preferable, 11% by weight is further preferable, and 13% by weight is used. % Is particularly preferred, 15% by weight is very preferred, and 16% by weight is most preferred.
  • the upper limit of the molybdenum content is preferably 30% by weight, more preferably 25% by weight, still more preferably 20% by weight, from the viewpoint of facilitating adjustment of the surface resistance value.
  • the resistance layer contains molybdenum
  • nickel and chromium in addition to molybdenum in the resistance layer, a more durable radio wave absorber can be obtained.
  • alloys containing nickel, chromium and molybdenum include Hastelloy B-2, B-3, C-4, C-2000, C-22, C-276, G-30, N, W and X. Various grades can be mentioned.
  • the resistance layer contains molybdenum, nickel and chromium
  • the molybdenum content is 5% by weight or more
  • the nickel content is 40% by weight or more
  • the chromium content is 1% by weight or more.
  • the molybdenum, nickel and chromium contents are more preferably 7% by weight or more, nickel content of 45% by weight or more, and chromium content of 3% by weight or more.
  • the molybdenum, nickel and chromium contents are more preferably 9% by weight or more, the nickel content is 47% by weight or more, and the chromium content is 5% by weight or more.
  • the molybdenum, nickel and chromium contents are more preferably 11% by weight or more, the nickel content is 50% by weight or more, and the chromium content is 10% by weight or more.
  • the contents of molybdenum, nickel and chromium it is particularly preferable that the molybdenum content is 13% by weight or more, the nickel content is 53% by weight or more, and the chromium content is 12% by weight or more.
  • the molybdenum content is 15% by weight or more, the nickel content is 55% by weight or more, and the chromium content is 15% by weight or more.
  • the molybdenum, nickel and chromium contents are 16% by weight or more, the nickel content is 57% by weight or more, and the chromium content is 16% by weight or more.
  • the nickel content is preferably 80% by weight or less, more preferably 70% by weight or less, and further preferably 65% by weight or less.
  • the upper limit of the chromium content is preferably 50% by weight or less, more preferably 40% by weight or less, and further preferably 35% by weight or less.
  • the resistance layer may contain a metal other than molybdenum, nickel and chromium.
  • a metal include iron, cobalt, tungsten, manganese, titanium and the like.
  • the upper limit of the total content of metals other than molybdenum, nickel and chromium is preferably 45% by weight, more preferably 40, from the viewpoint of durability of the resistance layer. It is by weight%, more preferably 35% by weight, even more preferably 30% by weight, particularly preferably 25% by weight, and very preferably 23% by weight.
  • the lower limit of the total content of the metals other than molybdenum, nickel and chromium is, for example, 1% by weight or more.
  • the preferable upper limit of the content is 25% by weight, the more preferable upper limit is 20% by weight, the further preferable upper limit is 15% by weight, and the preferable lower limit is 15% by weight from the viewpoint of the durability of the resistance layer. 1% by weight.
  • the preferable upper limit of the content is 5% by weight, the more preferable upper limit is 4% by weight, and the further preferable upper limit is independently from the viewpoint of the durability of the resistance layer. It is 3% by weight, and the preferable lower limit is 0.1% by weight.
  • the preferable upper limit of the content is 8% by weight, the more preferable upper limit is 6% by weight, the further preferable upper limit is 4% by weight, and the preferable lower limit is 4% by weight from the viewpoint of the durability of the resistance layer. 1% by weight.
  • the resistance layer may contain silicon and / or carbon.
  • the content of silicon and / or carbon is preferably 1% by weight or less, more preferably 0.5% by weight or less, respectively. ..
  • the content of the silicon and / or carbon is preferably 0.01% by weight or more.
  • the resistance film preferably includes a barrier layer.
  • the barrier layer is placed on at least one surface of the resistance layer.
  • the barrier layer will be described in detail below.
  • the barrier layer is not particularly limited as long as it is a layer that can protect the resistance layer and suppress its deterioration.
  • the material of the barrier layer include metal compounds, metalloid compounds, preferably metal or metalloid oxides, nitrides, nitride oxides and the like.
  • the barrier layer may contain components other than the above-mentioned materials as long as the effects of the present invention are not significantly impaired. In that case, the amount of the material in the barrier layer is, for example, 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 99% by mass or more, and usually less than 100% by mass. ..
  • Examples of the metal element contained in the barrier layer include titanium, aluminum, niobium, cobalt, nickel and the like.
  • Examples of the metalloid element contained in the barrier layer include silicon, germanium, antimony, and bismuth.
  • MO X As the oxide, for example, MO X [in the formula, X is a number satisfying the formula: n / 100 ⁇ X ⁇ n / 2 (n is a valence of a metal or a metalloid), and M is a metal element or It is a metalloid element. ], Examples thereof include compounds represented by.
  • MN y As the above-mentioned nitride, for example, MN y [in the formula, Y is a number satisfying the formula: n / 100 ⁇ Y ⁇ n / 3 (n is a valence of a metal or a metalloid), and M is a metal element or It is a metalloid element. ], Examples thereof include compounds represented by.
  • nitride oxide examples include MO X N y [in the formula, X and Y are n / 100 ⁇ X, n / 100 ⁇ Y, and X + Y ⁇ n / 2 (n is a metal or metalloid valence). ), And M is a metal element or a metalloid element. ], Examples thereof include compounds represented by.
  • the cross section of the layer containing MOx or MOxNy is elementally analyzed by FE-TEM-EDX (for example, "JEM-ARM200F” manufactured by JEOL Ltd.), and MOx or
  • the valence of oxygen atoms can be calculated by calculating X from the elemental ratio of M and O per area of the cross section of the layer containing MOxNy.
  • the cross section of the layer containing MN y or MO x N y is elementalized by FE-TEM-EDX (for example, "JEM-ARM200F” manufactured by JEOL Ltd.).
  • the valence of nitrogen atoms can be calculated by analyzing and calculating Y from the elemental ratio of M and N per area of the cross section of the layer containing MN y or MO x N y.
  • the material of the barrier layer include SiO 2 , SiO x , Al 2 O 3 , MgAl 2 O 4 , CuO, CuN, TiO 2 , TiN, AZO (aluminum-doped zinc oxide) and the like.
  • the thickness of the barrier layer is not particularly limited.
  • the thickness of the barrier layer is, for example, 1 nm or more and 200 nm or less, preferably 1 nm or more and 100 nm or less, and more preferably 1 nm or more and 20 nm or less.
  • the layer structure of the barrier layer is not particularly limited.
  • the barrier layer may be composed of one type of barrier layer alone, or may be a combination of two or more types of barrier layers.
  • the dielectric layer can function as a dielectric for a target wavelength in a radio wave absorber, and is not particularly limited as long as it has two or more regions having a thickness difference of 15 ⁇ m or more.
  • the dielectric layer is not particularly limited, and examples thereof include an adhesive layer, a resin sheet, and a foam layer.
  • the pressure-sensitive adhesive layer is not particularly limited as long as it contains a pressure-sensitive adhesive.
  • the pressure-sensitive adhesive layer may contain components other than the pressure-sensitive adhesive as long as the effects of the present invention are not significantly impaired.
  • the total amount of the resin in the resin sheet is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and usually less than 100% by mass. is there.
  • the adhesive is not particularly limited, and for example, acrylic adhesive, urethane adhesive, polyolefin adhesive, polyester adhesive, vinyl alkyl ether adhesive, polyamide adhesive, rubber adhesive, silicone adhesive. Examples thereof include adhesives and fluorine-based adhesives. Among these, an acrylic pressure-sensitive adhesive is preferable from the viewpoint of high weather resistance.
  • the resin sheet is not particularly limited as long as it is in the form of a sheet containing resin as a material.
  • the resin sheet may contain components other than the resin as long as the effects of the present invention are not significantly impaired.
  • the total amount of the resin in the resin sheet is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and usually less than 100% by mass. is there.
  • the resin is not particularly limited, and is, for example, ethylene vinyl acetate copolymer (EVA), vinyl chloride, urethane, acrylic, acrylic urethane, polyolefin, polyethylene, polypropylene, silicone, polyethylene terephthalate, polyester, polystyrene, polyimide, polycarbonate, polyamide. , Polysulfon, polyether sulfone, synthetic resins such as epoxy, polyisoprene rubber, polystyrene / butadiene rubber, polybutadiene rubber, chloroprene rubber, acrylonitrile / butadiene rubber, butyl rubber, acrylic rubber, ethylene / propylene rubber, silicone rubber, etc. It is preferable to use a rubber material as a resin component. These can be used alone or in combination of two or more.
  • EVA ethylene vinyl acetate copolymer
  • vinyl chloride urethane
  • acrylic acrylic urethane
  • polyolefin polyethylene
  • the dielectric layer may have adhesiveness. Therefore, when a dielectric having no adhesiveness is laminated on another layer by the pressure-sensitive adhesive layer, the combination of the dielectric and the pressure-sensitive adhesive layer becomes a "dielectric layer".
  • the dielectric layer preferably includes an adhesive layer from the viewpoint of easy stacking with the adjacent layer.
  • the relative permittivity of the dielectric layer is not particularly limited.
  • the relative permittivity of the dielectric layer is, for example, 1 to 20, preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5.
  • the relative permittivity of the dielectric layer can be measured by using a network analyzer, a cavity resonator, or the like to measure the relative permittivity at 10 GHz by the cavity resonator perturbation method.
  • the thickness of each of the two or more regions in the dielectric layer is not particularly limited.
  • the thickness of each region of the dielectric layer is, for example, 100 to 1000 ⁇ m, preferably 200 to 800 ⁇ m, more preferably 300 to 700 ⁇ m, and even more preferably 350 to 650 ⁇ m.
  • the thickness of each of the two or more regions of the dielectric layer can be measured by Nikon DIGIMICRO STANDMS-11C + Nikon DIGIMICRO MFC-101.
  • the difference in thickness between two or more regions in the dielectric layer is not particularly limited as long as it is 15 ⁇ m or more, but is, for example, 25 ⁇ m or more, 50 ⁇ m or more, and 100 ⁇ m or more.
  • the difference is preferably 350 ⁇ m or less, more preferably 200 ⁇ m or less, from the viewpoint that the thickness of the absorber can be reduced.
  • the radio wave absorption peak position when the difference in thickness is provided in this way substantially coincides with the radio wave absorption peak position calculated by regarding the area average thickness of the dielectric layer having a step as the thickness of the dielectric layer. Therefore, the difference in thickness, area, and thickness of each of the two or more regions in the dielectric layer is designed according to the target radio wave absorption peak position (that is, the area average thickness of the dielectric layer having the thickness difference). Can be designed).
  • the thickness of the dielectric layer can be measured as follows.
  • the thickness of the dielectric is measured with a thickness gauge (Nikon DIGIMICRO STANDMS-11C + Nikon DIGIMICRO MFC-101 or equivalent).
  • each of the high and low portions is measured at 5 points or more, and the value obtained by subtracting the average thickness of the low portion from the average thickness of the high portion is defined as the thickness difference.
  • the thickness of the dielectric layer in the ⁇ / 4 type radio wave absorber for example, the thickness of the ⁇ / 4 type radio wave absorber is first measured, and the laminated body other than the dielectric layer is formed from the total thickness of the ⁇ / 4 type radio wave absorber. It can be calculated by subtracting the thickness of the layer (for example, resistance film layer, reflective layer, etc.). The measurement is performed at 5 points, and the average value is taken as the thickness.
  • the area average thickness of the body layer is calculated by the formula: (d1 ⁇ A + d2 ⁇ B + d3 ⁇ C) / 100.
  • at least one of the difference between d1 and d2, the difference between d2 and d3, and the difference between d3 and d1 is 25 ⁇ m or more.
  • the area average thickness of the dielectric layer is preferably 100 to 800 ⁇ m, more preferably 200 to 800 ⁇ m because it is excellent in radio wave absorption (particularly radio wave absorption for high frequency radio waves).
  • the thickness can be appropriately adjusted according to the frequency of the radio wave targeted by the radio wave absorber and the dielectric constant of the dielectric.
  • the area average thickness of the dielectric layer is preferably 350 ⁇ m or more. It is 740 ⁇ m or less, more preferably 415 ⁇ m or more and 680 ⁇ m or less.
  • the thickness of each of the two or more regions in the dielectric layer is preferably 80 to 120%, more preferably 80 to 120%, based on the area average thickness of the dielectric layer of 100%, from the viewpoint that the total thickness of the absorber can be reduced. Is 90 to 110%, more preferably 95 to 105%.
  • the area of each of the two or more regions in the dielectric layer is not particularly limited.
  • the area is, for example, 0.1 cm 2 or more, 0.3 cm 2 or more, 1 cm 2 or more, 3 cm 2 or more, 10 cm 2 or more, 30 cm 2 or more, or 100 cm 2 or more.
  • the upper limit of the area is not particularly limited, for example, 10000 cm 2 or less, 3000 cm 2 or less, 1000 cm 2 or less, 300 cm 2 or less, 100 cm 2 or less, 30 cm 2 or less, or 10 cm 2 or less.
  • the width of each of the two or more regions in the dielectric layer is not particularly limited, and can be appropriately adjusted depending on the wavelength of the radio wave to be absorbed and the irradiation range.
  • the width is, for example, 0.1 cm or more, or 1 cm or more.
  • the upper limit of the width is not particularly limited, and is, for example, 10000 cm or less, 3000 cm or less, 1000 cm or less, 300 cm or less, 100 cm or less, 30 cm or less, or 10 cm or less.
  • the layer structure of the dielectric layer is not particularly limited.
  • the dielectric layer may be composed of one type of single dielectric layer, or may be a combination of two or more types of dielectric layers.
  • a three-layer structure dielectric layer composed of a non-adhesive dielectric and adhesive layers arranged on both sides thereof, a one-layer structure dielectric layer composed of an adhesive dielectric, and the like can be mentioned.
  • the method for forming two or more regions having different thicknesses in the dielectric layer is not particularly limited, and for example, a method using a known method can be adopted. For example, a method of laminating a plurality of dielectric layers having different thicknesses so as not to overlap each other, a method of laminating a dielectric layer having a uniform thickness, and a method of further laminating a dielectric layer on a part thereof can be mentioned.
  • the reflective layer is not particularly limited as long as it can function as a radio wave reflecting layer in the radio wave absorber.
  • the reflective layer is not particularly limited, and examples thereof include a metal film.
  • the metal film is not particularly limited as long as it is a layer containing metal as a material.
  • the metal film may contain a component other than the metal as long as the effect of the present invention is not significantly impaired.
  • the total amount of the metal in the metal film is, for example, 30% by mass or more, preferably 50% by mass or more, more preferably 75% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more. , Particularly preferably 95% by mass or more, very preferably 99% by mass or more, and usually less than 100% by mass.
  • the metal is not particularly limited, and examples thereof include aluminum, copper, iron, silver, gold, chromium, nickel, molybdenum, gallium, zinc, tin, niobium, and indium. Further, a metal compound such as ITO can also be used as a material for the metal film. These may be one kind alone or a combination of two or more kinds.
  • the thickness of the reflective layer is not particularly limited.
  • the thickness of the reflective layer is, for example, 1 ⁇ m or more and 500 ⁇ m or less, preferably 2 ⁇ m or more and 200 ⁇ m or less, and more preferably 5 ⁇ m or more and 100 ⁇ m or less.
  • the layer structure of the reflective layer is not particularly limited.
  • the reflective layer may be composed of one type of single reflective layer, or may be a combination of a plurality of two or more types of reflective layers.
  • the ⁇ / 4 type radio wave absorber of the present invention preferably further has a support.
  • the support is not particularly limited as long as it is in the form of a sheet.
  • the support is not particularly limited, and examples thereof include a resin base material.
  • the resin base material is a base material containing resin as a material, and is not particularly limited as long as it is in the form of a sheet.
  • the resin base material may contain components other than the resin as long as the effects of the present invention are not significantly impaired.
  • titanium oxide or the like may be contained from the viewpoint of adjusting the relative permittivity.
  • the total amount of the resin in the resin base material is, for example, 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 99% by mass or more, and usually less than 100% by mass.
  • the resin is not particularly limited, and is, for example, a polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate, or modified polyester, a polyolefin such as a polyethylene (PE) resin, a polypropylene (PP) resin, a polystyrene resin, or a cyclic olefin resin.
  • a polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate, or modified polyester
  • a polyolefin such as a polyethylene (PE) resin, a polypropylene (PP) resin, a polystyrene resin, or a cyclic olefin resin.
  • vinyl resins such as polyvinyl chloride and vinylidene chloride, polyvinyl acetal resins such as polyvinyl butyral (PVB), polyether ether ketone (PEEK) resin, polysulfone (PSF) resin, polyether sulfone (
  • polyester resin is preferable, and polyethylene terephthalate is more preferable, from the viewpoint of productivity and strength.
  • the relative permittivity of the support is not particularly limited.
  • the relative permittivity of the support is, for example, 1 to 20, preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5.
  • the thickness of the support is not particularly limited.
  • the thickness of the support is, for example, 5 ⁇ m or more and 500 ⁇ m or less, preferably 10 ⁇ m or more and 300 ⁇ m or less, and more preferably 20 ⁇ m or more and 300 ⁇ m or less.
  • the layer structure of the support is not particularly limited.
  • the support may be composed of one type of support alone, or may be a combination of a plurality of types of two or more types of supports.
  • each layer is arranged in the order in which the radio wave absorption performance can be exhibited.
  • the resistance film, the dielectric layer, and the reflective layer are arranged in this order.
  • the ⁇ / 4 type radio wave absorber of the present invention has a support, as an example, the support, the resistance film, the dielectric layer, and the reflective layer are arranged in this order.
  • the ⁇ / 4 type radio wave absorber of the present invention may include other layers in addition to the support, the resistance film, the dielectric layer, and the reflective layer.
  • the other layer may be placed on the surface of either the support, the resistance film, the dielectric layer, and the reflective layer, respectively.
  • Examples of the other layer include an adhesive layer arranged on the surface of the reflective layer opposite to the dielectric layer side.
  • This pressure-sensitive adhesive layer makes it possible to easily attach the ⁇ / 4 type radio wave absorber of the present invention by another member (for example, a device in an automobile). From this viewpoint, in the ⁇ / 4 type radio wave absorber of the present invention, it is preferable that the pressure-sensitive adhesive layer is arranged on the surface of the reflective layer opposite to the dielectric layer side.
  • the adhesive is not particularly limited, and for example, acrylic adhesive, urethane adhesive, polyolefin adhesive, polyester adhesive, vinyl alkyl ether adhesive, polyamide adhesive, rubber adhesive, silicone adhesive. Examples thereof include adhesives and fluorine-based adhesives.
  • the radio wave absorption peak position of the ⁇ / 4 type radio wave absorber of the present invention is preferably 10 GHz or more and 150 GHz or less, more preferably 20 GHz or more and 120 GHz or less, still more preferably 30 GHz or more and 110 GHz or less, still more preferably 55 GHz or more and 110 GHz or less, particularly. It is preferably 55 GHz or more and 90 GHz or less, and more preferably 70 GHz or more and 90 GHz or less.
  • the radio wave absorption amount of the ⁇ / 4 type radio wave absorber of the present invention at 60 to 90 GHz is preferably 15 dB or more, more preferably 20 dB or more, still more preferably 25 dB or more.
  • the radio wave absorption amount of the ⁇ / 4 type radio wave absorber of the present invention at 70 to 90 GHz is preferably 15 dB or more, more preferably 20 dB or more, still more preferably 25 dB or more.
  • the radio wave absorption peak position and the radio wave absorption amount are measured by the following method.
  • Network analyzer MS4647B manufactured by Anritsu
  • free space material measuring device BD1-26 free space material measuring device BD1-26.
  • a radio wave absorption measuring device is configured using A (manufactured by Keycom), and the radio wave absorption amount of the ⁇ / 4 type radio wave absorber obtained by using this radio wave absorption measuring device in the 55 to 90 GHz band is based on JIS R1679. Can be measured.
  • the ⁇ / 4 type radio wave absorber is set so that the radio wave incident direction is vertical incident and incident from the resistance film side.
  • the ⁇ / 4 type radio wave absorber of the present invention On the outermost surface of the ⁇ / 4 type radio wave absorber of the present invention (at least one of the surface on the resistance film layer side and the surface on the reflection layer side), another layer follows the step of the dielectric layer, and the above-mentioned dielectric layer A structure that reflects the difference in thickness and structure of the above can be formed. That is, it is preferable that the ⁇ / 4 type radio wave absorber of the present invention has two or more regions having a thickness difference of 15 ⁇ m or more on the outermost surface (the surface on the resistance film layer side or the surface on the reflection layer side).
  • the difference in thickness is more preferably 25 ⁇ m or more, still more preferably 50 ⁇ m or more, and more preferably 100 ⁇ m or more.
  • the thickness difference is preferably 350 ⁇ m or less, more preferably 200 ⁇ m or less, from the viewpoint that the thickness of the absorber can be reduced.
  • the area and the like of each region are the same as those of each region in the above-mentioned dielectric layer. Further, as the resistance film, the reflective film and the dielectric, the same ones as described above can be used.
  • the thickness difference can be measured as follows. Measure the thickness of the ⁇ / 4 type radio wave absorber with a thickness meter (Nikon DIGIMICRO STANDMS-11C + Nikon DIGIMICRO MFC-101 or equivalent). Five or more points are measured at each of the high and low portions of the step of the ⁇ / 4 type radio wave absorber, and the value obtained by subtracting the average thickness of the low portion from the average value of the thickness of the high portion is defined as the thickness difference.
  • a structure reflecting the step of the dielectric layer can be formed on the outermost surface of the ⁇ / 4 type radio wave absorber of the present invention (at least one of the surface on the resistance film layer side and the surface on the reflection layer side).
  • the resistance film layer or the reflective layer may not be formed on the raised portion (step surface in the step-terrace structure) of the step.
  • a step formed by following the step of the dielectric layer by another layer is formed.
  • the ⁇ / 4 type radio wave absorber of the present invention can be provided with various properties / functions (for example, surface design, wiring space due to dents, drip property, etc.) utilizing the step on the surface.
  • the step may be formed on both the resistance film layer side surface and the reflection layer side surface.
  • the ⁇ / 4 type radio wave absorber of the present invention On the outermost surface of the ⁇ / 4 type radio wave absorber of the present invention (at least one of the surface on the resistance film layer side and the surface on the reflection layer side), another layer follows the step of the dielectric layer, and the above-mentioned dielectric layer A structure that reflects the difference in thickness and structure of the above can be formed. That is, the ⁇ / 4 type radio wave absorber of the present invention preferably has a surface roughness Rz of 7.5 ⁇ m or more on its outermost surface (at least one of the surface on the resistance film layer side and the surface on the reflection layer side).
  • the present invention includes a resistance film, a dielectric layer, and a reflection layer, and has a surface roughness Rz on the outermost surface (at least one of the surface on the resistance film layer side and the surface on the reflection layer side).
  • the present invention relates to a ⁇ / 4 type radio wave absorber having a thickness of 7.5 ⁇ m or more.
  • the Rz is more preferably 15 ⁇ m or more, still more preferably 25 ⁇ m or more, even more preferably 50 ⁇ m or more, and particularly preferably 100 ⁇ m or more.
  • the upper limit of the Rz is not particularly limited, but is preferably 350 ⁇ m or less, more preferably 200 ⁇ m or less, from the viewpoint that the thickness of the absorber can be reduced.
  • the step may be formed on both the resistance film layer side surface and the reflection layer side surface. Further, as the resistance film, the reflective film and the dielectric, the same ones as described above can be used.
  • the surface roughness Rz on the outermost surface (the surface on the resistance film layer side or the surface on the reflection layer side) of the ⁇ / 4 type radio wave absorber can be measured as follows. It can be measured by a surface roughness meter (manufactured by Tokyo Seimitsu Co., Ltd., trade name Surfcom 1800A or its equivalent) based on JIS B0601 (2001).
  • the ⁇ / 4 type radio wave absorber of the present invention can be obtained according to or according to various methods, for example, a known manufacturing method, depending on its configuration. For example, it can be obtained by a method including a step of sequentially laminating a resistance film, a dielectric layer, and a reflective layer on a support.
  • the stacking method is not particularly limited.
  • the resistance film can be formed by, for example, a sputtering method, a vacuum vapor deposition method, an ion plating method, a chemical vapor deposition method, a pulse laser deposition method, or the like.
  • the sputtering method is preferable from the viewpoint of film thickness controllability.
  • the sputtering method is not particularly limited, and examples thereof include DC magnetron sputtering, high frequency magnetron sputtering, and ion beam sputtering.
  • the sputtering apparatus may be a batch system or a roll-to-roll system.
  • the dielectric layer and the reflective layer can be laminated by utilizing, for example, the adhesiveness of the dielectric layer.
  • the present invention includes a resistance film and a dielectric layer, and the dielectric layer has two or more regions having a thickness difference of 15 ⁇ m or more. It relates to a member for a type 4 radio wave absorber.
  • the member for the ⁇ / 4 type radio wave absorber preferably further includes a support.
  • the ⁇ / 4 type radio wave absorber member is a member for forming a ⁇ / 4 type radio wave absorber by arranging it in contact with an adherend (housing or the like) that can function as a reflective layer.
  • the support, resistance film, dielectric layer, and other configurations are the same as those described for the ⁇ / 4 type radio wave absorber of the present invention.
  • the ⁇ / 4 type radio wave absorber of the present invention has the ability to absorb unnecessary electromagnetic waves, and is therefore suitable as a radio wave countermeasure member in, for example, optical transceivers, next-generation mobile communication systems (5G), short-range wireless transfer technology, and the like. Can be used for. In addition, it should also be used for the purpose of suppressing radio wave interference and reducing noise in intelligent transportation systems (ITS) that communicate information between automobiles, roads, and people, and millimeter-wave radars used in automobile collision prevention systems. Can be done.
  • ITS intelligent transportation systems
  • the present invention relates to, in one embodiment, a molded product and a molded product with a radio wave absorber, which comprises the ⁇ / 4 type radio wave absorber of the present invention attached to the molded product.
  • the molded product include members used in the above-mentioned various uses.
  • the method of attaching the ⁇ / 4 type radio wave absorber of the present invention to the molded product is not particularly limited, and examples thereof include a method of attaching via an adhesive and a method of attaching with a fixture.
  • a preferred example of a molded product with a radio wave absorber is a millimeter wave radar.
  • the frequency of the radio wave targeted by the ⁇ / 4 type radio wave absorber of the present invention is preferably 10 GHz or more and 150 GHz or less, more preferably 20 GHz or more and 120 GHz or less, still more preferably 30 GHz or more and 110 GHz or less, still more preferably 55 GHz or more and 110 GHz or less. It is particularly preferably 55 GHz or more and 90 GHz or less, and more preferably 70 GHz or more and 90 GHz or less.
  • the ⁇ / 4 type radio wave absorber of the present invention is installed so as to have two or more regions in which the difference in thickness of the above-mentioned dielectric layer is 15 ⁇ m or more within the irradiation range of the target radio wave. Is preferable. Further, the ⁇ / 4 type radio wave absorber of the present invention has the shape of each region and the installation location of the radio wave absorber so as to have the area average thickness of the above-mentioned dielectric layer within the range irradiated with the target radio wave. It is preferable to adjust.
  • an adhesive tape double-sided adhesive tape used for the dielectric layer was manufactured as follows. Acrylic with a width of 10 cm, a length of 10 cm, a thickness of 500 ⁇ m and a relative permittivity of 2.5 on one side of an acrylic double-sided adhesive tape having a width of 1 cm, a length of 10 cm, a thickness of 100 ⁇ m and a relative permittivity of 2.5. Double-sided adhesive tapes were laminated with a distance of 1 cm each.
  • a ⁇ / 4 type radio wave absorber was manufactured as follows.
  • a white polyethylene terephthalate (PET) film (relative permittivity 3.4) having a thickness of 125 ⁇ m was prepared.
  • Sputtering was carried out using Hastelloy C-276 as a target, introduced at an output of 0.4 kW and an Ar gas flow rate of 100 sccm, and adjusted to a pressure of 0.12 Pa.
  • the dielectric layer made of the adhesive tape was laminated on the formed resistance film with the stepped side facing the resistance film side, and the reflective layer made of copper having a thickness of 12 ⁇ m was laminated on the dielectric layer. Then, a ⁇ / 4 type radio wave absorber was obtained.
  • Example 2 An acrylic double-sided adhesive tape having a thickness of 100 ⁇ m and a relative permittivity of 3.6 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 400 ⁇ m and a relative permittivity of 3.6 so as to form a stripe.
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • Example 4 An acrylic double-sided adhesive tape having a thickness of 100 ⁇ m and a relative permittivity of 3.6 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 400 ⁇ m and a relative permittivity of 3.6 so as to form a stripe. At this time, the width of the stripes was laminated so that the ratio of the non-laminated portion to the laminated portion was 4: 1.
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • Example 5 An acrylic double-sided adhesive tape having a thickness of 150 ⁇ m and a relative permittivity of 3.0 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 450 ⁇ m and a relative permittivity of 3.0.
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • Example 7 An acrylic double-sided adhesive tape having a thickness of 150 ⁇ m and a relative permittivity of 3.0 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 450 ⁇ m and a relative permittivity of 3.0. At this time, the width of the stripes was laminated so that the ratio of the non-laminated portion to the laminated portion was 4: 1.
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • Example 8 A dielectric made of polycarbonate having a thickness of 400 ⁇ m and a relative permittivity of 2.6 and a dielectric made of polycarbonate having a thickness of 500 ⁇ m and a relative permittivity of 2.6 on one side of an acrylic double-sided adhesive tape having a thickness of 30 ⁇ m and a relative permittivity of 3.0.
  • the bodies were arranged alternately in a striped pattern. Further, an acrylic double-sided adhesive tape having a thickness of 30 ⁇ m and a relative permittivity of 3.0 is laminated on it, and a region having a thickness of 460 ⁇ m (area is 50% of the total) and a region having a thickness of 560 ⁇ m (area is 50% of the total) are formed.
  • Example 11 A dielectric made of polycarbonate having a thickness of 300 ⁇ m and a relative permittivity of 2.6 and a dielectric made of polycarbonate having a thickness of 500 ⁇ m and a relative permittivity of 2.6 on one side of an acrylic double-sided adhesive tape having a thickness of 30 ⁇ m and a relative permittivity of 3.0. After cutting the body into small pieces of 10 mm square, they were arranged alternately in a checkered pattern.
  • an acrylic double-sided adhesive tape having a thickness of 30 ⁇ m and a relative permittivity of 3.0 is laminated on the tape, and the region has a thickness of 360 ⁇ m (the area is 50% of the total) and the region has a thickness of 560 ⁇ m (the area is 50% of the total).
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • Example 12 On one side of an acrylic double-sided adhesive tape with a thickness of 30 ⁇ m and a relative permittivity of 3.0, a dielectric made of polycarbonate having a thickness of 200 ⁇ m and a relative dielectric constant of 2.6 and a dielectric made of polycarbonate having a thickness of 300 ⁇ m and a relative dielectric constant of 2.6 After cutting the body, a dielectric made of polycarbonate having a thickness of 400 ⁇ m and a relative permittivity of 2.6, and a dielectric made of polycarbonate having a thickness of 500 ⁇ m and a relative permittivity of 2.6 into 50 mm squares, one piece each having a thickness of 50 mm square. was arranged so as to form a 100 mm square.
  • an acrylic double-sided adhesive tape with a thickness of 30 ⁇ m and a relative permittivity of 3.0 is laminated on it, and a region with a thickness of 260 ⁇ m (area is 25% of the total), a region with a thickness of 360 ⁇ m (area is 25% of the total), and a thickness.
  • a ⁇ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
  • the ⁇ / 4 type radio wave absorbers of Examples 1 to 8 exhibited good radio wave absorption characteristics in a target wavelength range even though the dielectric layer had a relatively large step.
  • the radio wave absorption peak position when the step is provided almost coincides with the radio wave absorption peak position calculated by regarding the area average thickness of the dielectric layer having the step as the thickness of the dielectric layer. That is, it was found that the radio wave absorption peak position when the step is provided can be controlled based on the respective thicknesses of the thick region and the thin region of the dielectric layer and their area ratios.
  • a step was formed on the surface on the support side following the step of the dielectric layer. From this, when the dielectric layer is positively provided with a step, various properties and functions (for example, surface design, wiring space due to dents, drip property, etc.) can be imparted by utilizing the step on the surface. Do you get it.

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Abstract

The present invention addresses the problem of providing new technology for controlling the wave absorption characteristics of a λ/4 wave absorber. In view of the knowledge that the wave absorption peak position in the case where steps are provided to a dielectric layer can be controlled on the basis of the respective thicknesses and area ratio of the thick areas and thin areas of the dielectric layer, the present invention provides a λ/4 wave absorber that includes a stepped dielectric layer.

Description

λ／４型電波吸収体λ / 4 type radio wave absorber
　本発明は、λ／４型電波吸収体等に関する。 The present invention relates to a λ / 4 type radio wave absorber and the like.
　近年、携帯電話やスマートフォン等の携帯通信機器の普及が急速に進んでおり、また自動車等において多くの電子機器が搭載されるようになり、これらから発生する電波・ノイズを原因とする電波障害、他の電子機器の誤動作等の問題が多発している。このような電波障害、誤動作等を防止する方策として、各種の電波吸収体が検討されている。例えば、特許文献１には、６０～９０ＧＨｚの周波数帯域において、電磁波吸収量が２０ｄＢ以上である周波数帯域の帯域幅が２ＧＨｚ以上である電磁波吸収体が開示されている。 In recent years, mobile communication devices such as mobile phones and smartphones have rapidly become widespread, and many electronic devices have come to be installed in automobiles, etc., and radio interference caused by radio waves and noise generated from these devices, Problems such as malfunction of other electronic devices occur frequently. Various radio wave absorbers are being studied as measures to prevent such radio interference and malfunction. For example, Patent Document 1 discloses an electromagnetic wave absorber having a bandwidth of 2 GHz or more in a frequency band having an electromagnetic wave absorption amount of 20 dB or more in a frequency band of 60 to 90 GHz.
特開２０１８－０９８３６７号公報JP-A-2018-098367
　一般的に、λ／４型電波吸収体においては、吸収性能向上のために、誘電体層の厚みのばらつきが問題となる。すなわち、誘電体層の厚みのばらつきが大きいと、電波吸収ピーク波長が設計値からずれてしまい、結果として目的の波長の電波吸収特性が低下してしまう。このため、従来は、誘電体層の厚みを可能な限り均一にすることにより、電波吸収特性を制御していた。 Generally, in a λ / 4 type radio wave absorber, variation in the thickness of the dielectric layer becomes a problem in order to improve the absorption performance. That is, if the thickness of the dielectric layer varies widely, the radio wave absorption peak wavelength deviates from the design value, and as a result, the radio wave absorption characteristic of the target wavelength deteriorates. Therefore, conventionally, the radio wave absorption characteristics have been controlled by making the thickness of the dielectric layer as uniform as possible.
　本発明は、λ／４型電波吸収体において電波吸収特性を制御する新たな技術を提供することを課題とする。 An object of the present invention is to provide a new technique for controlling radio wave absorption characteristics in a λ / 4 type radio wave absorber.
　本発明者は、上記課題に鑑みて鋭意研究を進めた結果、誘電体層に段差を設けても、目的の波長範囲において良好な電波吸収特性を発揮できることを見出した。そして、さらに解析を進めた結果、段差を設けた場合の電波吸収ピーク位置は、段差を有する誘電体層の面積平均厚みを誘電体層の厚みとみなして算出される電波吸収ピーク位置にほぼ一致すること、すなわち、段差を設けた場合の電波吸収ピーク位置は、誘電体層の厚い領域と薄い領域のそれぞれの厚みとそれらの面積比に基づいて制御できることが分かった。従来は、誘電体層の厚みを可能な限り均一にすることが求められていたところ、この結果は驚くべきことであった。本発明者はこれらの知見に基づいてさらに研究を進めた結果、本発明を完成させた。 As a result of diligent research in view of the above problems, the present inventor has found that even if a step is provided in the dielectric layer, good radio wave absorption characteristics can be exhibited in a target wavelength range. As a result of further analysis, the radio wave absorption peak position when the step is provided almost coincides with the radio wave absorption peak position calculated by regarding the area average thickness of the dielectric layer having the step as the thickness of the dielectric layer. That is, it was found that the radio wave absorption peak position when the step is provided can be controlled based on the respective thicknesses of the thick region and the thin region of the dielectric layer and their area ratios. In the past, it was required to make the thickness of the dielectric layer as uniform as possible, and this result was surprising. The present inventor has completed the present invention as a result of further research based on these findings.
　即ち、本発明は、下記の態様を包含する。 That is, the present invention includes the following aspects.
　項１．　抵抗膜、誘電体層、及び反射層を含み、前記誘電体層が、厚みの差が１５μｍ以上である２つ以上の領域を有する、λ／４型電波吸収体。 Item 1. A λ / 4 type radio wave absorber including a resistance film, a dielectric layer, and a reflective layer, wherein the dielectric layer has two or more regions having a thickness difference of 15 μm or more.
　項２．　前記厚みの差が３５０μｍ以下である、項１に記載のλ／４型電波吸収体。 Item 2. Item 2. The λ / 4 type radio wave absorber according to Item 1, wherein the difference in thickness is 350 μm or less.
　項３．　前記２つ以上の各領域の厚みが、前記誘電体層の面積平均厚み１００％に対して、８０～１２０％である、項１又は２に記載のλ／４型電波吸収体。 Item 3. Item 2. The λ / 4 type radio wave absorber according to Item 1 or 2, wherein the thickness of each of the two or more regions is 80 to 120% with respect to the area average thickness of the dielectric layer of 100%.
　項４．　前記誘電体層の面積平均厚みが１００～８００μｍである、項１～３のいずれかに記載のλ／４型電波吸収体。 Item 4. Item 2. The λ / 4 type radio wave absorber according to any one of Items 1 to 3, wherein the area average thickness of the dielectric layer is 100 to 800 μm.
　項５．　６０～９０ＧＨｚにおける電波吸収量が１５ｄＢ以上である、項１～４のいずれかに記載のλ／４型電波吸収体。 Item 5. Item 4. The λ / 4 type radio wave absorber according to any one of Items 1 to 4, wherein the radio wave absorption amount at 60 to 90 GHz is 15 dB or more.
　項６Ａ．　抵抗膜、誘電体層、及び反射層を含み、前記抵抗膜層側表面及び前記反射層側表面表面のうち少なくとも一方におけるＲｚが７．５μｍ以上である、λ／４型電波吸収体。 Item 6A. A λ / 4 type radio wave absorber containing a resistance film, a dielectric layer, and a reflection layer, and having an Rz of 7.5 μm or more on at least one of the resistance film layer side surface and the reflection layer side surface surface.
　項６Ｂ．　抵抗膜、誘電体層、及び反射層を含み、最表面において厚みの差が１５μｍ以上である、λ／４型電波吸収体。 Item 6B. A λ / 4 type radio wave absorber that includes a resistance film, a dielectric layer, and a reflective layer, and has a thickness difference of 15 μm or more on the outermost surface.
　項７．　成形品と、前記成形品に取り付けられた項１～５のいずれかに記載のλ／４型電波吸収体とを備える、電波吸収体付成形品。 Item 7. A molded product with a radio wave absorber, comprising the molded product and the λ / 4 type radio wave absorber according to any one of Items 1 to 5 attached to the molded product.
　項８．　ミリ波レーダーである、項６に記載の電波吸収体付成形品。 Item 8. Item 6. A molded product with a radio wave absorber, which is a millimeter-wave radar.
　項９．　抵抗膜及び誘電体層を含み、前記誘電体層が、厚みの差が２５μｍ以上である２つ以上の領域を有する、λ／４型電波吸収体用部材。 Item 9. A λ / 4 type radio wave absorber member including a resistance film and a dielectric layer, wherein the dielectric layer has two or more regions having a thickness difference of 25 μm or more.
　本発明によれば、電波吸収特性を制御する新たな技術を提供することができる。すなわち、誘電体層に段差を設けた場合の電波吸収ピーク位置は、誘電体層の厚い領域と薄い領域のそれぞれの厚みとそれらの面積比に基づいて制御できるという知見に基づいて、段差を有する誘電体層を含むλ／４型電波吸収体、さらにはその段差に追従して形成された段差を表面に有するλ／４型電波吸収体を提供することができる。 According to the present invention, it is possible to provide a new technique for controlling radio wave absorption characteristics. That is, the radio wave absorption peak position when the dielectric layer is provided with a step has a step based on the knowledge that the radio wave absorption peak position can be controlled based on the respective thicknesses of the thick region and the thin region of the dielectric layer and their area ratios. It is possible to provide a λ / 4 type radio wave absorber including a dielectric layer, and further, a λ / 4 type radio wave absorber having a step formed following the step on the surface.
本発明のλ／４型電波吸収体の一例の断面外略図を示す。A schematic cross-sectional view of an example of the λ / 4 type radio wave absorber of the present invention is shown. 本発明のλ／４型電波吸収体の一例の断面外略図を示す。A schematic cross-sectional view of an example of the λ / 4 type radio wave absorber of the present invention is shown. 本発明のλ／４型電波吸収体の一例の上面図（Ａ）及び断面概略図（Ｂ）を示す。上面図中、グレー部が凸部を示し、白色部が凹部を示す。A top view (A) and a schematic cross-sectional view (B) of an example of the λ / 4 type radio wave absorber of the present invention are shown. In the top view, the gray part shows the convex part and the white part shows the concave part. 本発明のλ／４型電波吸収体の一例の上面図を示す。上面図中、グレー部が凸部を示し、白色部が凹部を示す。The top view of an example of the λ / 4 type radio wave absorber of this invention is shown. In the top view, the gray part shows the convex part and the white part shows the concave part. 本発明のλ／４型電波吸収体部材の一例の断面外略図を示す。A schematic cross-sectional view of an example of the λ / 4 type radio wave absorber member of the present invention is shown. 本発明の電波吸収体付成形品の一例の断面外略図を示す。A schematic cross-sectional view of an example of a molded product with a radio wave absorber of the present invention is shown.
　本明細書中において、「含有」及び「含む」なる表現については、「含有」、「含む」、「実質的にからなる」及び「のみからなる」という概念を含む。 In the present specification, the expressions "contains" and "contains" include the concepts of "contains", "contains", "substantially consists" and "consists of only".
　１．λ／４型電波吸収体
　本発明は、その一態様において、抵抗膜、誘電体層、及び反射層を含み、前記誘電体層が、厚みの差が１５μｍ以上である２つ以上の領域を有する、λ／４型電波吸収体（本明細書において、「本発明のλ／４型電波吸収体」と示すこともある。）、に関する。以下に、これについて説明する。 1. 1. λ / 4 type radio wave absorber In one aspect of the present invention, the present invention includes a resistance film, a dielectric layer, and a reflective layer, and the dielectric layer has two or more regions having a thickness difference of 15 μm or more. , Λ / 4 type radio wave absorber (in the present specification, it may be referred to as “λ / 4 type radio wave absorber of the present invention”). This will be described below.
　＜１－１．抵抗膜＞
　抵抗膜は、電波吸収体において抵抗層として機能し得る層を含む限り特に制限されない。 <1-1. Resistive film>
The resistance film is not particularly limited as long as it includes a layer that can function as a resistance layer in the radio wave absorber.
　抵抗膜の抵抗値は、特に制限されない。抵抗膜の抵抗値（シート抵抗）は、例えば１００～８００Ω／□である。該範囲の中でも、より好ましくは１５０～７５０Ω／□、さらに好ましくは２００～６００Ω／□である。 The resistance value of the resistance film is not particularly limited. The resistance value (sheet resistance) of the resistance film is, for example, 100 to 800 Ω / □. Within this range, it is more preferably 150 to 750 Ω / □, still more preferably 200 to 600 Ω / □.
　抵抗膜の抵抗値は、表面抵抗計（ＭＩＴＳＵＢＩＳＨＩ　ＣＨＥＭＩＣＡＬ　ＡＮＡＬＹＴＥＣＨ社製、商品名「Ｌｏｒｅｓｔａ－ＥＰ」）を用いて、４端子法により測定することができる。また、抵抗値は、後述する支持体等が積層され抵抗膜を直接測定できない場合は、非接触抵抗計（製品名「ＥＣ－８０Ｐ、ナプソン社製、又はその同等品）を用いて渦電流法により、支持体の抵抗膜とは逆の表面から測定することができる。 The resistance value of the resistance film can be measured by the 4-terminal method using a surface resistance meter (MITSUBISHI CHEMICAL ANALYTECH, trade name "Loresta-EP"). The resistance value is determined by the eddy current method using a non-contact resistance tester (product name "EC-80P, manufactured by Napson, or an equivalent product)" when a support or the like described later is laminated and the resistance film cannot be measured directly. Therefore, it is possible to measure from the surface opposite to the resistance film of the support.
　抵抗膜の厚みは、本発明の特性を満たし得る抵抗値となるものである限り特に制限されない。抵抗膜の厚みは、例えば１ｎｍ以上２００ｎｍ以下、好ましくは２ｎｍ以上１００ｎｍ以下、より好ましくは２ｎｍ以上５０ｎｍ以下である。 The thickness of the resistance film is not particularly limited as long as it has a resistance value that can satisfy the characteristics of the present invention. The thickness of the resistance film is, for example, 1 nm or more and 200 nm or less, preferably 2 nm or more and 100 nm or less, and more preferably 2 nm or more and 50 nm or less.
　抵抗膜の層構成は特に制限されない。抵抗膜は、１種単独の層から構成されるものであってもよいし、２種以上の層が複数組み合わされたものであってもよい。 The layer structure of the resistance film is not particularly limited. The resistance film may be composed of a single layer of one type, or may be a combination of a plurality of layers of two or more types.
　＜１－１－１．抵抗層＞
　抵抗層の抵抗値は、本発明の特性を満たし得るものである限り特に制限されない。抵抗層の抵抗値は、例えば１００～８００Ω／□である。該範囲の中でも、より好ましくは１５０～７５０Ω／□、さらに好ましくは２００～６００Ω／□である。 <1-1-1. Resistance layer>
The resistance value of the resistance layer is not particularly limited as long as it can satisfy the characteristics of the present invention. The resistance value of the resistance layer is, for example, 100 to 800 Ω / □. Within this range, it is more preferably 150 to 750 Ω / □, still more preferably 200 to 600 Ω / □.
　抵抗層の厚みは、本発明の特性を満たし得る抵抗値となるものである限り特に制限されない。抵抗層の厚みは、例えば１ｎｍ以上２００ｎｍ以下、好ましくは２ｎｍ以上１００ｎｍ以下、より好ましくは２ｎｍ以上５０ｎｍ以下である。 The thickness of the resistance layer is not particularly limited as long as it has a resistance value that can satisfy the characteristics of the present invention. The thickness of the resistance layer is, for example, 1 nm or more and 200 nm or less, preferably 2 nm or more and 100 nm or less, and more preferably 2 nm or more and 50 nm or less.
　抵抗層の層構成は特に制限されない。抵抗層は、１種単独の抵抗層から構成されるものであってもよいし、２種以上の抵抗層が複数組み合わされたものであってもよい。 The layer structure of the resistance layer is not particularly limited. The resistance layer may be composed of one type of resistance layer alone, or may be a combination of a plurality of types of resistance layers of two or more types.
　＜１－１－１－１．酸化インジウム含有抵抗層＞
　抵抗層としては、例えば酸化インジウム等の抵抗層材料を含有する抵抗層が挙げられる。好ましい一態様において、抵抗層材料としては、酸化インジウムに他の材料（ドーパント）がドープされてなる材料を含有することが好ましい。他の材料としては、特に制限されないが、例えば酸化スズ及び酸化亜鉛、並びにそれらの混合物等が挙げられる。 <1-1-1-1. Indium oxide-containing resistance layer>
Examples of the resistance layer include a resistance layer containing a resistance layer material such as indium oxide. In a preferred embodiment, the resistance layer material preferably contains a material obtained by doping indium oxide with another material (dopant). Other materials are not particularly limited, and examples thereof include tin oxide and zinc oxide, and mixtures thereof.
　酸化インジウムに酸化スズがドープされてなる材料の中でも、好ましくは、酸化インジウム（ＩＩＩ）（Ｉｎ２Ｏ３）に酸化スズ（ＩＶ）（ＳｎＯ２）をドープしたもの（酸化インジウムスズ）（ｔｉｎ－ｄｏｐｅｄ　ｉｎｄｉｕｍ　ｏｘｉｄｅ；ＩＴＯ）が挙げられる。非晶質構造が極めて安定であり、高温多湿の環境下においても抵抗層のシート抵抗の変動を抑えることができる点から、ＩＴＯ中のＳｎＯ２含有量は、好ましくは１～４０重量％、より好ましくは２～３５重量％である。 Among the materials obtained by doping indium oxide with tin oxide, preferably, indium (III) oxide (In 2 O 3 ) doped with tin (IV) (SnO 2 ) (indium tin oxide) (tin-). Doped indium oxide; ITO) can be mentioned. The SnO 2 content in ITO is preferably 1 to 40% by weight, because the amorphous structure is extremely stable and the fluctuation of the sheet resistance of the resistance layer can be suppressed even in a high temperature and high humidity environment. It is preferably 2 to 35% by weight.
　抵抗層中の上記抵抗層材料の含有量は、例えば５０質量％以上、好ましくは７０質量％以上、より好ましくは９０質量％以上、さらに好ましくは９５質量％以上であり、通常１００質量％未満である。 The content of the resistance layer material in the resistance layer is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and usually less than 100% by mass. is there.
　＜１－１－１－２．モリブデン含有抵抗層＞
　抵抗層としては、耐久性、シート抵抗の調整が容易である観点から、モリブデンを含有する抵抗層が好ましく用いられる。モリブデンの含有量の下限は特に限定されないが、より耐久性を高める観点から、５重量％が好ましく、７重量％がより好ましく、９重量％が更に好ましく、１１重量％がより更に好ましく、１３重量％が特に好ましく、１５重量％が非常に好ましく、１６重量％が最も好ましい。また、上記モリブデンの含有量の上限は、表面抵抗値の調整の容易化の観点から、３０重量％が好ましく、２５重量％がより好ましく、２０重量％が更に好ましい。 <1-1-1-2. Molybdenum-containing resistance layer>
As the resistance layer, a resistance layer containing molybdenum is preferably used from the viewpoint of durability and easy adjustment of sheet resistance. The lower limit of the molybdenum content is not particularly limited, but from the viewpoint of further enhancing durability, 5% by weight is preferable, 7% by weight is more preferable, 9% by weight is further preferable, 11% by weight is further preferable, and 13% by weight is used. % Is particularly preferred, 15% by weight is very preferred, and 16% by weight is most preferred. The upper limit of the molybdenum content is preferably 30% by weight, more preferably 25% by weight, still more preferably 20% by weight, from the viewpoint of facilitating adjustment of the surface resistance value.
　上記抵抗層は、モリブデンを含有している場合、さらにニッケル及びクロムを含有することがより好ましい。抵抗層にモリブデンに加えてニッケル及びクロムを含有することでより耐久性に優れた電波吸収体とすることができる。ニッケル、クロム及びモリブデンを含有する合金としては、例えば、ハステロイＢ－２、Ｂ－３、Ｃ－４、Ｃ－２０００、Ｃ－２２、Ｃ－２７６、Ｇ－３０、Ｎ、Ｗ、Ｘ等の各種グレードが挙げられる。 When the resistance layer contains molybdenum, it is more preferable that it further contains nickel and chromium. By containing nickel and chromium in addition to molybdenum in the resistance layer, a more durable radio wave absorber can be obtained. Examples of alloys containing nickel, chromium and molybdenum include Hastelloy B-2, B-3, C-4, C-2000, C-22, C-276, G-30, N, W and X. Various grades can be mentioned.
　上記抵抗層がモリブデン、ニッケル及びクロムを含有する場合、モリブデンの含有量が５重量％以上、ニッケルの含有量が４０重量％以上、クロムの含有量が１重量％以上であることが好ましい。モリブデン、ニッケル及びクロムの含有量が上記範囲であることで、より耐久性に優れた電波吸収体とすることができる。上記モリブデン、ニッケル及びクロムの含有量は、モリブデン含有量が７重量％以上、ニッケル含有量が４５重量％以上、クロム含有量が３重量％以上であることがより好ましい。上記モリブデン、ニッケル及びクロムの含有量は、モリブデン含有量が９重量％以上、ニッケル含有量が４７重量％以上、クロム含有量が５重量％以上であることが更に好ましい。上記モリブデン、ニッケル及びクロムの含有量は、モリブデン含有量が１１重量％以上、ニッケル含有量が５０重量％以上、クロム含有量が１０重量％以上であることがより更に好ましい。上記モリブデン、ニッケル及びクロムの含有量は、モリブデン含有量が１３重量％以上、ニッケル含有量が５３重量％以上、クロム含有量が１２重量％以上であることが特に好ましい。上記モリブデン、ニッケル及びクロムの含有量は、モリブデン含有量が１５重量％以上、ニッケル含有量が５５重量％以上、クロム含有量が１５重量％以上であることが非常に好ましい。上記モリブデン、ニッケル及びクロムの含有量は、モリブデン含有量が１６重量％以上、ニッケル含有量が５７重量％以上、クロム含有量が１６重量％以上であることが最も好ましい。また、上記ニッケルの含有量は、８０重量％以下であることが好ましく、７０重量％以下であることがより好ましく、６５重量％以下であることが更に好ましい。上記クロム含有量の上限は、５０重量％以下であることが好ましく、４０重量％以下であることがより好ましく、３５重量％以下であることが更に好ましい。 When the resistance layer contains molybdenum, nickel and chromium, it is preferable that the molybdenum content is 5% by weight or more, the nickel content is 40% by weight or more, and the chromium content is 1% by weight or more. When the contents of molybdenum, nickel and chromium are in the above range, a radio wave absorber having more excellent durability can be obtained. The molybdenum, nickel and chromium contents are more preferably 7% by weight or more, nickel content of 45% by weight or more, and chromium content of 3% by weight or more. The molybdenum, nickel and chromium contents are more preferably 9% by weight or more, the nickel content is 47% by weight or more, and the chromium content is 5% by weight or more. The molybdenum, nickel and chromium contents are more preferably 11% by weight or more, the nickel content is 50% by weight or more, and the chromium content is 10% by weight or more. As for the contents of molybdenum, nickel and chromium, it is particularly preferable that the molybdenum content is 13% by weight or more, the nickel content is 53% by weight or more, and the chromium content is 12% by weight or more. As for the contents of molybdenum, nickel and chromium, it is very preferable that the molybdenum content is 15% by weight or more, the nickel content is 55% by weight or more, and the chromium content is 15% by weight or more. Most preferably, the molybdenum, nickel and chromium contents are 16% by weight or more, the nickel content is 57% by weight or more, and the chromium content is 16% by weight or more. The nickel content is preferably 80% by weight or less, more preferably 70% by weight or less, and further preferably 65% by weight or less. The upper limit of the chromium content is preferably 50% by weight or less, more preferably 40% by weight or less, and further preferably 35% by weight or less.
　上記抵抗層は、上記モリブデン、ニッケル及びクロム以外の金属を含有してもよい。そのような金属としては、例えば、鉄、コバルト、タングステン、マンガン、チタン等が挙げられる。上記抵抗層がモリブデン、ニッケル及びクロムを含有する場合、上記モリブデン、ニッケル及びクロム以外の金属の合計含有量の上限は、抵抗層の耐久性の観点から、好ましくは４５重量％、より好ましくは４０重量％、更に好ましくは３５重量％、より更に好ましくは３０重量％、特に好ましくは２５重量％、非常に好ましくは２３重量％である。上記モリブデン、ニッケル及びクロム以外の金属の合計含有量の下限は、例えば１重量％以上である。 The resistance layer may contain a metal other than molybdenum, nickel and chromium. Examples of such a metal include iron, cobalt, tungsten, manganese, titanium and the like. When the resistance layer contains molybdenum, nickel and chromium, the upper limit of the total content of metals other than molybdenum, nickel and chromium is preferably 45% by weight, more preferably 40, from the viewpoint of durability of the resistance layer. It is by weight%, more preferably 35% by weight, even more preferably 30% by weight, particularly preferably 25% by weight, and very preferably 23% by weight. The lower limit of the total content of the metals other than molybdenum, nickel and chromium is, for example, 1% by weight or more.
　上記抵抗層が鉄を含有する場合、抵抗層の耐久性の観点から、含有量の好ましい上限は２５重量％、より好ましい上限は２０重量％、更に好ましい上限は１５重量％であり、好ましい下限は１重量％である。上記抵抗層がコバルト及び／又はマンガンを含有する場合、抵抗層の耐久性の観点から、それぞれ独立して、含有量の好ましい上限は５重量％、より好ましい上限は４重量％、更に好ましい上限は３重量％であり、好ましい下限は０．１重量％である。上記抵抗層がタングステンを含有する場合、抵抗層の耐久性の観点から、含有量の好ましい上限は８重量％、より好ましい上限は６重量％、更に好ましい上限は４重量％であり、好ましい下限は１重量％である。 When the resistance layer contains iron, the preferable upper limit of the content is 25% by weight, the more preferable upper limit is 20% by weight, the further preferable upper limit is 15% by weight, and the preferable lower limit is 15% by weight from the viewpoint of the durability of the resistance layer. 1% by weight. When the resistance layer contains cobalt and / or manganese, the preferable upper limit of the content is 5% by weight, the more preferable upper limit is 4% by weight, and the further preferable upper limit is independently from the viewpoint of the durability of the resistance layer. It is 3% by weight, and the preferable lower limit is 0.1% by weight. When the resistance layer contains tungsten, the preferable upper limit of the content is 8% by weight, the more preferable upper limit is 6% by weight, the further preferable upper limit is 4% by weight, and the preferable lower limit is 4% by weight from the viewpoint of the durability of the resistance layer. 1% by weight.
　上記抵抗層は、ケイ素及び／又は炭素を含有してもよい。抵抗層がケイ素及び／又は炭素を含有する場合、上記ケイ素及び／又は炭素の含有量は、それぞれ独立して、１重量％以下であることが好ましく０．５重量％以下であることがより好ましい。また、抵抗層がケイ素及び／又は炭素を含有する場合、上記ケイ素及び／又は炭素の含有量は、０．０１重量％以上であることが好ましい。 The resistance layer may contain silicon and / or carbon. When the resistance layer contains silicon and / or carbon, the content of silicon and / or carbon is preferably 1% by weight or less, more preferably 0.5% by weight or less, respectively. .. When the resistance layer contains silicon and / or carbon, the content of the silicon and / or carbon is preferably 0.01% by weight or more.
　＜１－１－２．バリア層＞
　耐久性の観点から、抵抗膜はバリア層を含むことが好ましい。バリア層は、抵抗層の少なくとも一方の表面上に配置される。バリア層について以下に詳述する。 <1-1-2. Barrier layer>
From the viewpoint of durability, the resistance film preferably includes a barrier layer. The barrier layer is placed on at least one surface of the resistance layer. The barrier layer will be described in detail below.
　バリア層は、抵抗層を保護し、その劣化を抑えることができる層である限り、特に制限されない。バリア層の素材としては、例えば金属化合物、半金属化合物、好ましくは金属又は半金属の酸化物、窒化物、窒化酸化物等が挙げられる。バリア層は、本発明の効果が著しく損なわれない限りにおいて、上記素材以外の成分が含まれていてもよい。その場合、バリア層中の上記素材量は、例えば８０質量％以上、好ましくは９０質量％以上、より好ましくは９５質量％以上、さらに好ましくは９９質量％以上であり、通常１００質量％未満である。 The barrier layer is not particularly limited as long as it is a layer that can protect the resistance layer and suppress its deterioration. Examples of the material of the barrier layer include metal compounds, metalloid compounds, preferably metal or metalloid oxides, nitrides, nitride oxides and the like. The barrier layer may contain components other than the above-mentioned materials as long as the effects of the present invention are not significantly impaired. In that case, the amount of the material in the barrier layer is, for example, 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 99% by mass or more, and usually less than 100% by mass. ..
　バリア層が含む金属元素としては、例えばチタン、アルミニウム、ニオブ、コバルト、ニッケル等が挙げられる。バリア層が含む半金属元素としては、例えばケイ素、ゲルマニウム、アンチモン、ビスマス等が挙げられる。 Examples of the metal element contained in the barrier layer include titanium, aluminum, niobium, cobalt, nickel and the like. Examples of the metalloid element contained in the barrier layer include silicon, germanium, antimony, and bismuth.
　上記酸化物としては、例えばＭＯＸ［式中、Ｘは式：ｎ／１００≦Ｘ≦ｎ／２（ｎは金属又は半金属の価数である）を満たす数であり、Ｍは金属元素又は半金属元素である。］で表される化合物が挙げられる。 As the oxide, for example, MO X [in the formula, X is a number satisfying the formula: n / 100 ≦ X ≦ n / 2 (n is a valence of a metal or a metalloid), and M is a metal element or It is a metalloid element. ], Examples thereof include compounds represented by.
　上記窒化物としては、例えばＭＮｙ［式中、Ｙは式：ｎ／１００≦Ｙ≦ｎ／３（ｎは金属又は半金属の価数である）を満たす数であり、Ｍは金属元素又は半金属元素である。］で表される化合物が挙げられる。 As the above-mentioned nitride, for example, MN y [in the formula, Y is a number satisfying the formula: n / 100 ≦ Y ≦ n / 3 (n is a valence of a metal or a metalloid), and M is a metal element or It is a metalloid element. ], Examples thereof include compounds represented by.
　上記窒化酸化物としては、例えばＭＯＸＮｙ［式中、ＸとＹは、ｎ／１００≦Ｘ、ｎ／１００≦Ｙ、かつ、Ｘ＋Ｙ≦ｎ／２（ｎは金属又は半金属の価数である）であり、Ｍは金属元素又は半金属元素である。］で表される化合物が挙げられる。 Examples of the nitride oxide include MO X N y [in the formula, X and Y are n / 100 ≦ X, n / 100 ≦ Y, and X + Y ≦ n / 2 (n is a metal or metalloid valence). ), And M is a metal element or a metalloid element. ], Examples thereof include compounds represented by.
　上記酸化物又は窒化酸化物の酸化数Ｘに関しては、例えばＭＯｘ又はＭＯｘＮｙを含む層の断面を、ＦＥ－ＴＥＭ－ＥＤＸ（例えば、日本電子社製「ＪＥＭ－ＡＲＭ２００Ｆ」）により元素分析し、ＭＯｘ又はＭＯｘＮｙを含む層の断面の面積当たりのＭとＯとの元素比率からＸを算出することにより、酸素原子の価数を算出することができる。 Regarding the oxidation number X of the oxide or nitride oxide, for example, the cross section of the layer containing MOx or MOxNy is elementally analyzed by FE-TEM-EDX (for example, "JEM-ARM200F" manufactured by JEOL Ltd.), and MOx or The valence of oxygen atoms can be calculated by calculating X from the elemental ratio of M and O per area of the cross section of the layer containing MOxNy.
　上記窒化物又は窒化酸化物の窒素化数Ｙに関しては、例えばＭＮｙ又はＭＯｘＮｙを含む層の断面を、ＦＥ－ＴＥＭ－ＥＤＸ（例えば、日本電子社製「ＪＥＭ－ＡＲＭ２００Ｆ」）により元素分析し、ＭＮｙ又はＭＯｘＮｙを含む層の断面の面積当たりのＭとＮとの元素比率からＹを算出することにより、窒素原子の価数を算出することができる。 Regarding the nitrogen oxide number Y of the nitride or nitride oxide, for example , the cross section of the layer containing MN y or MO x N y is elementalized by FE-TEM-EDX (for example, "JEM-ARM200F" manufactured by JEOL Ltd.). The valence of nitrogen atoms can be calculated by analyzing and calculating Y from the elemental ratio of M and N per area of the cross section of the layer containing MN y or MO x N y.
　バリア層の素材の具体例としては、ＳｉＯ２、ＳｉＯｘ、Ａｌ２Ｏ３、ＭｇＡｌ２Ｏ４、ＣｕＯ、ＣｕＮ、ＴｉＯ２、ＴｉＮ、ＡＺＯ（アルミニウムドープ酸化亜鉛）等が挙げられる。 Specific examples of the material of the barrier layer include SiO 2 , SiO x , Al 2 O 3 , MgAl 2 O 4 , CuO, CuN, TiO 2 , TiN, AZO (aluminum-doped zinc oxide) and the like.
　バリア層の厚みは、特に制限されない。バリア層の厚みは、例えば１ｎｍ以上２００ｎｍ以下、好ましくは１ｎｍ以上１００ｎｍ以下、より好ましくは１ｎｍ以上２０ｎｍ以下である。 The thickness of the barrier layer is not particularly limited. The thickness of the barrier layer is, for example, 1 nm or more and 200 nm or less, preferably 1 nm or more and 100 nm or less, and more preferably 1 nm or more and 20 nm or less.
　バリア層の層構成は特に制限されない。バリア層は、１種単独のバリア層から構成されるものであってもよいし、２種以上のバリア層が複数組み合わされたものであってもよい。 The layer structure of the barrier layer is not particularly limited. The barrier layer may be composed of one type of barrier layer alone, or may be a combination of two or more types of barrier layers.
　＜１－２．誘電体層＞
　誘電体層は、電波吸収体において目的の波長に対して誘電体として機能し得るものであって、厚みの差が１５μｍ以上である２つ以上の領域を有する限り、特に制限されない。誘電体層としては、特に制限されないが、例えば粘着剤層、樹脂シート、発泡体層等が挙げられる。 <1-2. Dielectric layer>
The dielectric layer can function as a dielectric for a target wavelength in a radio wave absorber, and is not particularly limited as long as it has two or more regions having a thickness difference of 15 μm or more. The dielectric layer is not particularly limited, and examples thereof include an adhesive layer, a resin sheet, and a foam layer.
　粘着剤層としては、粘着剤を含むものである限り、特に制限されない。粘着剤層は、本発明の効果が著しく損なわれない限りにおいて、粘着剤以外の成分が含まれていてもよい。その場合、樹脂シート中の樹脂の合計量は、例えば５０質量％以上、好ましくは７０質量％以上、より好ましくは９０質量％以上、さらに好ましくは９５質量％以上であり、通常１００質量％未満である。 The pressure-sensitive adhesive layer is not particularly limited as long as it contains a pressure-sensitive adhesive. The pressure-sensitive adhesive layer may contain components other than the pressure-sensitive adhesive as long as the effects of the present invention are not significantly impaired. In that case, the total amount of the resin in the resin sheet is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and usually less than 100% by mass. is there.
　粘着剤としては、特に制限されず、例えばアクリル系粘着剤、ウレタン系粘着剤、ポリオレフィン系粘着剤、ポリエステル系粘着剤、ビニルアルキルエーテル系粘着剤、ポリアミド系粘着剤、ゴム系粘着剤、シリコーン系粘着剤、フッ素系粘着剤等が挙げられる。これらの中でも、耐候性が高いという観点から、アクリル系粘着剤が好ましい。 The adhesive is not particularly limited, and for example, acrylic adhesive, urethane adhesive, polyolefin adhesive, polyester adhesive, vinyl alkyl ether adhesive, polyamide adhesive, rubber adhesive, silicone adhesive. Examples thereof include adhesives and fluorine-based adhesives. Among these, an acrylic pressure-sensitive adhesive is preferable from the viewpoint of high weather resistance.
　樹脂シートは、樹脂を素材として含むシート状のものである限り、特に制限されない。樹脂シートは、本発明の効果が著しく損なわれない限りにおいて、樹脂以外の成分が含まれていてもよい。その場合、樹脂シート中の樹脂の合計量は、例えば５０質量％以上、好ましくは７０質量％以上、より好ましくは９０質量％以上、さらに好ましくは９５質量％以上であり、通常１００質量％未満である。 The resin sheet is not particularly limited as long as it is in the form of a sheet containing resin as a material. The resin sheet may contain components other than the resin as long as the effects of the present invention are not significantly impaired. In that case, the total amount of the resin in the resin sheet is, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and usually less than 100% by mass. is there.
　樹脂としては、特に制限されず、例えばエチレン酢酸ビニル共重合体（ＥＶＡ）、塩化ビニル、ウレタン、アクリル、アクリルウレタン、ポリオレフィン、ポリエチレン、ポリプロピレン、シリコーン、ポリエチレンテレフタレート、ポリエステル、ポリスチレン、ポリイミド、ポリカーボネート、ポリアミド、ポリサルフォン、ポリエーテルサルフォン、エポキシ等の合成樹脂や、ポリイソプレンゴム、ポリスチレン・ブタジエンゴム、ポリブタジエンゴム、クロロプレンゴム、アクリロニトリル・ブタジエンゴム、ブチルゴム、アクリルゴム、エチレン・プロピレンゴムおよびシリコーンゴム等の合成ゴム材料を樹脂成分として用いることが好ましい。これらは１種単独でまたは２種以上の組合せで使用することができる。 The resin is not particularly limited, and is, for example, ethylene vinyl acetate copolymer (EVA), vinyl chloride, urethane, acrylic, acrylic urethane, polyolefin, polyethylene, polypropylene, silicone, polyethylene terephthalate, polyester, polystyrene, polyimide, polycarbonate, polyamide. , Polysulfon, polyether sulfone, synthetic resins such as epoxy, polyisoprene rubber, polystyrene / butadiene rubber, polybutadiene rubber, chloroprene rubber, acrylonitrile / butadiene rubber, butyl rubber, acrylic rubber, ethylene / propylene rubber, silicone rubber, etc. It is preferable to use a rubber material as a resin component. These can be used alone or in combination of two or more.
　誘電体層は、粘着性を備えるものであってもよい。このため、粘着性を有しない誘電体を粘着剤層により他の層に積層させる場合、該誘電体と粘着剤層とを合わせたものが「誘電体層」となる。隣接する層と積層し易いという観点から、誘電体層は、好ましくは粘着剤層を含む。 The dielectric layer may have adhesiveness. Therefore, when a dielectric having no adhesiveness is laminated on another layer by the pressure-sensitive adhesive layer, the combination of the dielectric and the pressure-sensitive adhesive layer becomes a "dielectric layer". The dielectric layer preferably includes an adhesive layer from the viewpoint of easy stacking with the adjacent layer.
　誘電体層の比誘電率は、特に制限されない。誘電体層の比誘電率は、例えば１～２０、好ましくは１～１５、より好ましくは１～１０、さらに好ましくは１～５である。 The relative permittivity of the dielectric layer is not particularly limited. The relative permittivity of the dielectric layer is, for example, 1 to 20, preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5.
　誘電体層の比誘電率は、ネットワークアナライザー、空洞共振器などを用いて１０ＧＨｚにおける比誘電率を空洞共振器摂動法により測定することができるによって測定することができる。 The relative permittivity of the dielectric layer can be measured by using a network analyzer, a cavity resonator, or the like to measure the relative permittivity at 10 GHz by the cavity resonator perturbation method.
　誘電体層における２つ以上の各領域の厚みは、特に制限されない。誘電体層の各領域の厚みは、例えば１００～１０００μｍ、好ましくは２００～８００μｍ、より好ましくは３００～７００μｍ、さらに好ましくは３５０～６５０μｍである。 The thickness of each of the two or more regions in the dielectric layer is not particularly limited. The thickness of each region of the dielectric layer is, for example, 100 to 1000 μm, preferably 200 to 800 μm, more preferably 300 to 700 μm, and even more preferably 350 to 650 μm.
　誘電体層の２つ以上の各領域の厚みは、Ｎｉｋｏｎ　ＤＩＧＩＭＩＣＲＯ　ＳＴＡＮＤＭＳ－１１Ｃ＋Ｎｉｋｏｎ　ＤＩＧＩＭＩＣＲＯ　ＭＦＣ－１０１によって測定することができる。 The thickness of each of the two or more regions of the dielectric layer can be measured by Nikon DIGIMICRO STANDMS-11C + Nikon DIGIMICRO MFC-101.
　誘電体層における２つ以上の各領域の厚みの差は、１５μｍ以上である限り、特に制限されないが例えば、２５μｍ以上、５０μｍ以上、１００μｍ以上である。該差は、吸収体厚みを薄くできるという観点から、好ましくは３５０μｍ以下、より好ましくは２００μｍ以下である。このように厚みの差を設けた場合の電波吸収ピーク位置は、段差を有する誘電体層の面積平均厚みを誘電体層の厚みとみなして算出される電波吸収ピーク位置にほぼ一致する。このため、目的の電波吸収ピーク位置に合わせて、誘電体層における２つ以上の各領域の厚み、面積、及び厚みの差を設計すること（すなわち、厚み差を有する誘電体層の面積平均厚みを設計すること）ができる。 The difference in thickness between two or more regions in the dielectric layer is not particularly limited as long as it is 15 μm or more, but is, for example, 25 μm or more, 50 μm or more, and 100 μm or more. The difference is preferably 350 μm or less, more preferably 200 μm or less, from the viewpoint that the thickness of the absorber can be reduced. The radio wave absorption peak position when the difference in thickness is provided in this way substantially coincides with the radio wave absorption peak position calculated by regarding the area average thickness of the dielectric layer having a step as the thickness of the dielectric layer. Therefore, the difference in thickness, area, and thickness of each of the two or more regions in the dielectric layer is designed according to the target radio wave absorption peak position (that is, the area average thickness of the dielectric layer having the thickness difference). Can be designed).
　誘電体層の厚みは次のように測定することができる。厚み計（Ｎｉｋｏｎ　ＤＩＧＩＭＩＣＲＯ　ＳＴＡＮＤＭＳ－１１Ｃ＋Ｎｉｋｏｎ　ＤＩＧＩＭＩＣＲＯ　ＭＦＣ－１０１又は同等品）により誘電体の厚みを測定する。該厚みの差については、高低部それぞれを５点以上測定し、高部の厚み平均値から低部の厚み平均値を差し引いた値を厚み差とする。
λ／４型電波吸収体における誘電体層の厚みは例えば、まずλ／４型電波吸収体の厚みを測定し、λ／４型電波吸収体の総厚みから誘電体層以外の積層体を構成する層（例えば抵抗膜層、反射層等）の厚みを差し引いて算出することができる。測定は５点で測定し、その平均値を厚みとする。 The thickness of the dielectric layer can be measured as follows. The thickness of the dielectric is measured with a thickness gauge (Nikon DIGIMICRO STANDMS-11C + Nikon DIGIMICRO MFC-101 or equivalent). Regarding the difference in thickness, each of the high and low portions is measured at 5 points or more, and the value obtained by subtracting the average thickness of the low portion from the average thickness of the high portion is defined as the thickness difference.
For the thickness of the dielectric layer in the λ / 4 type radio wave absorber, for example, the thickness of the λ / 4 type radio wave absorber is first measured, and the laminated body other than the dielectric layer is formed from the total thickness of the λ / 4 type radio wave absorber. It can be calculated by subtracting the thickness of the layer (for example, resistance film layer, reflective layer, etc.). The measurement is performed at 5 points, and the average value is taken as the thickness.
　誘電体層の面積平均厚みは、具体的には、次のように算出される。例えば、厚みｄ１の領域の面積がＡ％、厚みｄ２の領域の面積がＢ％、厚みｄ３の領域の面積がＣ％である場合（Ａ＋Ｂ＋Ｃ＝１００％（誘電体層の全面積））、誘電体層の面積平均厚みは、式：（ｄ１×Ａ＋ｄ２×Ｂ＋ｄ３×Ｃ）／１００　により算出される。本発明においては、ｄ１とｄ２との差、ｄ２とｄ３との差、及びｄ３とｄ１との差の少なくとも１つが２５μｍ以上である。 Specifically, the area average thickness of the dielectric layer is calculated as follows. For example, when the area of the region having the thickness d1 is A%, the area of the region having the thickness d2 is B%, and the area of the region having the thickness d3 is C% (A + B + C = 100% (total area of the dielectric layer)), the dielectric The area average thickness of the body layer is calculated by the formula: (d1 × A + d2 × B + d3 × C) / 100. In the present invention, at least one of the difference between d1 and d2, the difference between d2 and d3, and the difference between d3 and d1 is 25 μm or more.
　誘電体層の面積平均厚みは、電波吸収性（特に高周波数の電波に対する電波吸収性）に優れるため、好ましくは１００～８００μｍ、より好ましくは２００～８００μｍである。該厚みは電波吸収体が対象とする電波の周波数及び誘電体の誘電率に応じて適宜調整することができる。 The area average thickness of the dielectric layer is preferably 100 to 800 μm, more preferably 200 to 800 μm because it is excellent in radio wave absorption (particularly radio wave absorption for high frequency radio waves). The thickness can be appropriately adjusted according to the frequency of the radio wave targeted by the radio wave absorber and the dielectric constant of the dielectric.
　より具体的には、例えばλ／４型電波吸収体が対象とする電波の周波数が６０～９０ＧＨｚで誘電体の誘電率が２．５の場合、誘電体層の面積平均厚みは好ましくは３５０μｍ以上７４０μｍ以下であり、より好ましくは４１５μｍ以上６８０μｍ以下である。 More specifically, for example, when the frequency of the radio wave targeted by the λ / 4 type radio wave absorber is 60 to 90 GHz and the dielectric constant of the dielectric is 2.5, the area average thickness of the dielectric layer is preferably 350 μm or more. It is 740 μm or less, more preferably 415 μm or more and 680 μm or less.
　誘電体層における２つ以上の各領域の厚みは、吸収体の総厚みを薄くすることができる観点から、誘電体層の面積平均厚み１００％に対して、好ましくは８０～１２０％、より好ましくは９０～１１０％、さらに好ましくは９５～１０５％である。 The thickness of each of the two or more regions in the dielectric layer is preferably 80 to 120%, more preferably 80 to 120%, based on the area average thickness of the dielectric layer of 100%, from the viewpoint that the total thickness of the absorber can be reduced. Is 90 to 110%, more preferably 95 to 105%.
　誘電体層における２つ以上の各領域の面積は特に制限されない。該面積は、例えば０．１ｃｍ２以上、０．３ｃｍ２以上、１ｃｍ２以上、３ｃｍ２以上、１０ｃｍ２以上、３０ｃｍ２以上、又は１００ｃｍ２以上である。該面積の上限は特に制限されず、例えば１００００ｃｍ２以下、３０００ｃｍ２以下、１０００ｃｍ２以下、３００ｃｍ２以下、１００ｃｍ２以下、３０ｃｍ２以下、又は１０ｃｍ２以下である。 The area of each of the two or more regions in the dielectric layer is not particularly limited. The area is, for example, 0.1 cm 2 or more, 0.3 cm 2 or more, 1 cm 2 or more, 3 cm 2 or more, 10 cm 2 or more, 30 cm 2 or more, or 100 cm 2 or more. The upper limit of the area is not particularly limited, for example, 10000 cm 2 or less, 3000 cm 2 or less, 1000 cm 2 or less, 300 cm 2 or less, 100 cm 2 or less, 30 cm 2 or less, or 10 cm 2 or less.
　誘電体層における２つ以上の各領域の幅は特に制限されず、吸収対象とする電波の波長及び照射される範囲により適宜調整することができる。該幅は、例えば０．１ｃｍ以上、又は１ｃｍ以上である。該幅の上限は特に制限されず、例えば１００００ｃｍ以下、３０００ｃｍ以下、１０００ｃｍ以下、３００ｃｍ以下、１００ｃｍ以下、３０ｃｍ以下又は１０ｃｍ以下である。 The width of each of the two or more regions in the dielectric layer is not particularly limited, and can be appropriately adjusted depending on the wavelength of the radio wave to be absorbed and the irradiation range. The width is, for example, 0.1 cm or more, or 1 cm or more. The upper limit of the width is not particularly limited, and is, for example, 10000 cm or less, 3000 cm or less, 1000 cm or less, 300 cm or less, 100 cm or less, 30 cm or less, or 10 cm or less.
　誘電体層の層構成は特に制限されない。誘電体層は、１種単独の誘電体層から構成されるものであってもよいし、２種以上の誘電体層が複数組み合わされたものであってもよい。例えば、粘着性を有しない誘電体とその両面に配置された粘着剤層とからなる３層構造の誘電体層、粘着性を有する誘電体からなる１層構造の誘電体層等が挙げられる。 The layer structure of the dielectric layer is not particularly limited. The dielectric layer may be composed of one type of single dielectric layer, or may be a combination of two or more types of dielectric layers. For example, a three-layer structure dielectric layer composed of a non-adhesive dielectric and adhesive layers arranged on both sides thereof, a one-layer structure dielectric layer composed of an adhesive dielectric, and the like can be mentioned.
　誘電体層において厚みの差が異なる２つ以上の領域を形成する方法としては、特に制限されず、例えば公知の方法を利用した方法を採用することができる。例えば、厚みの異なる複数の誘電体層を互いに重ならないように積層する方法、均一の厚みの誘電体層を積層し、その上の一部にさらに誘電体層を積層する方法等が挙げられる。 The method for forming two or more regions having different thicknesses in the dielectric layer is not particularly limited, and for example, a method using a known method can be adopted. For example, a method of laminating a plurality of dielectric layers having different thicknesses so as not to overlap each other, a method of laminating a dielectric layer having a uniform thickness, and a method of further laminating a dielectric layer on a part thereof can be mentioned.
　＜１－３．反射層＞
　反射層は、電波吸収体において電波の反射層として機能し得るものである限り、特に制限されない。反射層としては、特に制限されないが、例えば金属膜が挙げられる。 <1-3. Reflective layer>
The reflective layer is not particularly limited as long as it can function as a radio wave reflecting layer in the radio wave absorber. The reflective layer is not particularly limited, and examples thereof include a metal film.
　金属膜は、金属を素材として含む層である限り、特に制限されない。金属膜は、本発明の効果が著しく損なわれない限りにおいて、金属以外の成分が含まれていてもよい。その場合、金属膜中の金属の合計量は、例えば３０質量％以上、好ましくは５０質量％以上、より好ましくは７５質量％以上、さらに好ましくは８０質量％以上、さらにより好ましくは９０質量％以上、特に好ましくは９５質量％以上、非常に好ましくは９９質量％以上であり、通常１００質量％未満である。 The metal film is not particularly limited as long as it is a layer containing metal as a material. The metal film may contain a component other than the metal as long as the effect of the present invention is not significantly impaired. In that case, the total amount of the metal in the metal film is, for example, 30% by mass or more, preferably 50% by mass or more, more preferably 75% by mass or more, still more preferably 80% by mass or more, still more preferably 90% by mass or more. , Particularly preferably 95% by mass or more, very preferably 99% by mass or more, and usually less than 100% by mass.
　金属としては、特に制限されず、例えばアルミニウム、銅、鉄、銀、金、クロム、ニッケル、モリブデン、ガリウム、亜鉛、スズ、ニオブ、インジウム等が挙げられる。また、金属化合物、例えばＩＴＯ等も、金属膜の素材として使用することができる。これらは１種単独であってもよいし、２種以上の組み合わせであってもよい。 The metal is not particularly limited, and examples thereof include aluminum, copper, iron, silver, gold, chromium, nickel, molybdenum, gallium, zinc, tin, niobium, and indium. Further, a metal compound such as ITO can also be used as a material for the metal film. These may be one kind alone or a combination of two or more kinds.
　反射層の厚みは、特に制限されない。反射層の厚みは、例えば１μｍ以上５００μｍ以下、好ましくは２μｍ以上２００μｍ以下、より好ましくは５μｍ以上１００μｍ以下である。 The thickness of the reflective layer is not particularly limited. The thickness of the reflective layer is, for example, 1 μm or more and 500 μm or less, preferably 2 μm or more and 200 μm or less, and more preferably 5 μm or more and 100 μm or less.
　反射層の層構成は特に制限されない。反射層は、１種単独の反射層から構成されるものであってもよいし、２種以上の反射層が複数組み合わされたものであってもよい。 The layer structure of the reflective layer is not particularly limited. The reflective layer may be composed of one type of single reflective layer, or may be a combination of a plurality of two or more types of reflective layers.
　＜１－４．支持体＞
　本発明のλ／４型電波吸収体は、さらに支持体を有することが好ましい。これにより、抵抗膜を保護することができ、電波吸収体としての耐久性を高めることが可能である。支持体は、シート状のものである限り、特に制限されない。支持体としては、特に制限されないが、例えば樹脂基材が挙げられる。 <1-4. Support>
The λ / 4 type radio wave absorber of the present invention preferably further has a support. As a result, the resistance film can be protected and the durability as a radio wave absorber can be enhanced. The support is not particularly limited as long as it is in the form of a sheet. The support is not particularly limited, and examples thereof include a resin base material.
　樹脂基材は、樹脂を素材として含む基材であって、シート状のものである限り、特に制限されない。樹脂基材は、本発明の効果が著しく損なわれない限りにおいて、樹脂以外の成分が含まれていてもよい。例えば、比誘電率を調整する観点から酸化チタン等が含まれていてもよい。樹脂基材中の樹脂の合計量は、例えば８０質量％以上、好ましくは９０質量％以上、より好ましくは９５質量％以上、さらに好ましくは９９質量％以上であり、通常１００質量％未満である。 The resin base material is a base material containing resin as a material, and is not particularly limited as long as it is in the form of a sheet. The resin base material may contain components other than the resin as long as the effects of the present invention are not significantly impaired. For example, titanium oxide or the like may be contained from the viewpoint of adjusting the relative permittivity. The total amount of the resin in the resin base material is, for example, 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 99% by mass or more, and usually less than 100% by mass.
　樹脂としては、特に制限されず、例えばポリエチレンテレフタレート（ＰＥＴ）、ポリエチレンナフタレート、変性ポリエステル等のポリエステル系樹脂、ポリエチレン（ＰＥ）樹脂、ポリプロピレン（ＰＰ）樹脂、ポリスチレン樹脂、環状オレフィン系樹脂等のポリオレフィン類樹脂、ポリ塩化ビニル、ポリ塩化ビニリデン等のビニル系樹脂、ポリビニルブチラール（ＰＶＢ）等のポリビニルアセタール樹脂、ポリエーテルエーテルケトン（ＰＥＥＫ）樹脂、ポリサルフォン（ＰＳＦ）樹脂、ポリエーテルサルフォン（ＰＥＳ）樹脂、ポリカーボネート（ＰＣ）樹脂、ポリアミド樹脂、ポリイミド樹脂、アクリル樹脂、トリアセチルセルロース（ＴＡＣ）樹脂等が挙げられる。これらは１種単独でまたは２種以上の組合せで使用することができる。 The resin is not particularly limited, and is, for example, a polyester resin such as polyethylene terephthalate (PET), polyethylene naphthalate, or modified polyester, a polyolefin such as a polyethylene (PE) resin, a polypropylene (PP) resin, a polystyrene resin, or a cyclic olefin resin. Similar resins, vinyl resins such as polyvinyl chloride and vinylidene chloride, polyvinyl acetal resins such as polyvinyl butyral (PVB), polyether ether ketone (PEEK) resin, polysulfone (PSF) resin, polyether sulfone (PES) resin. , Polycarbonate (PC) resin, polyamide resin, polyimide resin, acrylic resin, triacetyl cellulose (TAC) resin and the like. These can be used alone or in combination of two or more.
　これらの中でも、生産性や強度の観点から、好ましくはポリエステル系樹脂、より好ましくはポリエチレンテレフタレートが挙げられる。 Among these, polyester resin is preferable, and polyethylene terephthalate is more preferable, from the viewpoint of productivity and strength.
　支持体の比誘電率は、特に制限されない。支持体の比誘電率は、例えば１～２０、好ましくは１～１５、より好ましくは１～１０、さらに好ましくは１～５である。 The relative permittivity of the support is not particularly limited. The relative permittivity of the support is, for example, 1 to 20, preferably 1 to 15, more preferably 1 to 10, and even more preferably 1 to 5.
　支持体の厚みは、特に制限されない。支持体の厚みは、例えば５μｍ以上５００μｍ以下、好ましくは１０μｍ以上３００μｍ以下、より好ましくは２０μｍ以上３００μｍ以下である。 The thickness of the support is not particularly limited. The thickness of the support is, for example, 5 μm or more and 500 μm or less, preferably 10 μm or more and 300 μm or less, and more preferably 20 μm or more and 300 μm or less.
　支持体の層構成は特に制限されない。支持体は、１種単独の支持体から構成されるものであってもよいし、２種以上の支持体が複数組み合わされたものであってもよい。 The layer structure of the support is not particularly limited. The support may be composed of one type of support alone, or may be a combination of a plurality of types of two or more types of supports.
　＜１－５．層構成＞
　本発明のλ／４型電波吸収体において、各層は、電波吸収性能を発揮することができる順に配置される。一例として、抵抗膜、誘電体層、及び反射層は、この順に配置される。 <1-5. Layer structure>
In the λ / 4 type radio wave absorber of the present invention, each layer is arranged in the order in which the radio wave absorption performance can be exhibited. As an example, the resistance film, the dielectric layer, and the reflective layer are arranged in this order.
　さらに、本発明のλ／４型電波吸収体が支持体を有する場合、一例として、支持体、抵抗膜、誘電体層、及び反射層は、この順に配置される。 Further, when the λ / 4 type radio wave absorber of the present invention has a support, as an example, the support, the resistance film, the dielectric layer, and the reflective layer are arranged in this order.
　本発明のλ／４型電波吸収体においては、支持体、抵抗膜、誘電体層、及び反射層以外に、他の層を含むものであってもよい。他の層は、支持体、抵抗膜、誘電体層、及び反射層それぞれの層の、どちらか一方の表面上に配置され得る。 The λ / 4 type radio wave absorber of the present invention may include other layers in addition to the support, the resistance film, the dielectric layer, and the reflective layer. The other layer may be placed on the surface of either the support, the resistance film, the dielectric layer, and the reflective layer, respectively.
　他の層としては、例えば、反射層の誘電体層側とは反対側の面上に配置される粘着剤層が挙げられる。この粘着剤層により、本発明のλ／４型電波吸収体を、他の部材（例えば、自動車内のデバイス等）により容易に取り付けることが可能になる。この観点から、本発明のλ／４型電波吸収体は、反射層の誘電体層側とは反対側の面上に粘着剤層が配置されていることが好ましい。 Examples of the other layer include an adhesive layer arranged on the surface of the reflective layer opposite to the dielectric layer side. This pressure-sensitive adhesive layer makes it possible to easily attach the λ / 4 type radio wave absorber of the present invention by another member (for example, a device in an automobile). From this viewpoint, in the λ / 4 type radio wave absorber of the present invention, it is preferable that the pressure-sensitive adhesive layer is arranged on the surface of the reflective layer opposite to the dielectric layer side.
　粘着剤としては、特に制限されず、例えばアクリル系粘着剤、ウレタン系粘着剤、ポリオレフィン系粘着剤、ポリエステル系粘着剤、ビニルアルキルエーテル系粘着剤、ポリアミド系粘着剤、ゴム系粘着剤、シリコーン系粘着剤、フッ素系粘着剤等が挙げられる。 The adhesive is not particularly limited, and for example, acrylic adhesive, urethane adhesive, polyolefin adhesive, polyester adhesive, vinyl alkyl ether adhesive, polyamide adhesive, rubber adhesive, silicone adhesive. Examples thereof include adhesives and fluorine-based adhesives.
　＜１－６．特性、構造＞
　本発明のλ／４型電波吸収体の電波吸収ピーク位置は、好ましくは１０ＧＨｚ以上１５０ＧＨｚ以下、より好ましくは２０ＧＨｚ以上１２０ＧＨｚ以下、さらに好ましくは３０ＧＨｚ以上１１０ＧＨｚ以下、さらにより好ましくは５５ＧＨｚ以上１１０ＧＨｚ以下、特に好ましくは５５ＧＨｚ以上９０ＧＨｚ以下、一層好ましくは７０ＧＨｚ以上９０ＧＨｚ以下である。 <1-6. Characteristics, structure>
The radio wave absorption peak position of the λ / 4 type radio wave absorber of the present invention is preferably 10 GHz or more and 150 GHz or less, more preferably 20 GHz or more and 120 GHz or less, still more preferably 30 GHz or more and 110 GHz or less, still more preferably 55 GHz or more and 110 GHz or less, particularly. It is preferably 55 GHz or more and 90 GHz or less, and more preferably 70 GHz or more and 90 GHz or less.
　本発明のλ／４型電波吸収体の６０～９０ＧＨｚにおける電波吸収量は、好ましくは１５ｄＢ以上、より好ましくは２０ｄＢ以上、さらに好ましくは２５ｄＢ以上である。 The radio wave absorption amount of the λ / 4 type radio wave absorber of the present invention at 60 to 90 GHz is preferably 15 dB or more, more preferably 20 dB or more, still more preferably 25 dB or more.
　本発明のλ／４型電波吸収体の７０～９０ＧＨｚにおける電波吸収量は、好ましくは１５ｄＢ以上、より好ましくは２０ｄＢ以上、さらに好ましくは２５ｄＢ以上である。 The radio wave absorption amount of the λ / 4 type radio wave absorber of the present invention at 70 to 90 GHz is preferably 15 dB or more, more preferably 20 dB or more, still more preferably 25 dB or more.
　電波吸収ピーク位置及び電波吸収量は、次の方法によって測定される。ネットワークアナライザー　ＭＳ４６４７Ｂ（アンリツ社製）、フリースペース材料測定装置　ＢＤ１－２６．Ａ（キーコム社製）を用いて電波吸収測定装置を構成し、この電波吸収測定装置を用いて得られたλ／４型電波吸収体の５５～９０ＧＨｚ帯での電波吸収量をＪＩＳ　Ｒ１６７９に基づいて測定することができる。なお、λ／４型電波吸収体は、電波入射方向が垂直入射かつ抵抗膜側からの入射となるようにセットする。 The radio wave absorption peak position and the radio wave absorption amount are measured by the following method. Network analyzer MS4647B (manufactured by Anritsu), free space material measuring device BD1-26. A radio wave absorption measuring device is configured using A (manufactured by Keycom), and the radio wave absorption amount of the λ / 4 type radio wave absorber obtained by using this radio wave absorption measuring device in the 55 to 90 GHz band is based on JIS R1679. Can be measured. The λ / 4 type radio wave absorber is set so that the radio wave incident direction is vertical incident and incident from the resistance film side.
　本発明のλ／４型電波吸収体の最表面（抵抗膜層側表面及び反射層側の表面の少なくとも一方）においては、誘電体層の段差に他の層が追従し、上述の誘電体層の厚み差及び構造等が反映された構造が形成され得る。すなわち、本発明のλ／４型電波吸収体は、その最表面（抵抗膜層側表面又は反射層側表面）において厚みの差が１５μｍ以上である２つ以上の領域を有することが好ましい。 On the outermost surface of the λ / 4 type radio wave absorber of the present invention (at least one of the surface on the resistance film layer side and the surface on the reflection layer side), another layer follows the step of the dielectric layer, and the above-mentioned dielectric layer A structure that reflects the difference in thickness and structure of the above can be formed. That is, it is preferable that the λ / 4 type radio wave absorber of the present invention has two or more regions having a thickness difference of 15 μm or more on the outermost surface (the surface on the resistance film layer side or the surface on the reflection layer side).
　上記厚みの差はより好ましくはより好ましくは２５μｍ以上、さらに好ましくは５０μｍ以上、より好ましくは１００μｍ以上である。該厚み差は吸収体厚みを薄くできるという観点から、好ましくは３５０μｍ以下、より好ましくは２００μｍ以下である。それぞれの領域の面積等については、上述の誘電体層における各領域と同様である。また、抵抗膜、反射膜、誘電体については上述の説明と同様のものを用いることができる。 The difference in thickness is more preferably 25 μm or more, still more preferably 50 μm or more, and more preferably 100 μm or more. The thickness difference is preferably 350 μm or less, more preferably 200 μm or less, from the viewpoint that the thickness of the absorber can be reduced. The area and the like of each region are the same as those of each region in the above-mentioned dielectric layer. Further, as the resistance film, the reflective film and the dielectric, the same ones as described above can be used.
　該厚み差は、具体的には次のように測定することができる。厚み計（Ｎｉｋｏｎ　ＤＩＧＩＭＩＣＲＯ　ＳＴＡＮＤＭＳ－１１Ｃ＋Ｎｉｋｏｎ　ＤＩＧＩＭＩＣＲＯ　ＭＦＣ－１０１又は同等品）でλ／４型電波吸収体の厚みを測定する。λ／４型電波吸収体の段差の高低部それぞれを５点以上測定し、高部の厚みの平均値から低部の厚み平均値を差し引いた値を厚み差とする。 Specifically, the thickness difference can be measured as follows. Measure the thickness of the λ / 4 type radio wave absorber with a thickness meter (Nikon DIGIMICRO STANDMS-11C + Nikon DIGIMICRO MFC-101 or equivalent). Five or more points are measured at each of the high and low portions of the step of the λ / 4 type radio wave absorber, and the value obtained by subtracting the average thickness of the low portion from the average value of the thickness of the high portion is defined as the thickness difference.
　本発明のλ／４型電波吸収体の最表面（抵抗膜層側表面及び反射層側の表面の少なくとも一方）においては、誘電体層の段差を反映した構造が形成されうる。このとき段差の蹴込部（ステップ－テラス構造におけるステップ面）には抵抗膜層又は反射層が形成されていなくても良い。 On the outermost surface of the λ / 4 type radio wave absorber of the present invention (at least one of the surface on the resistance film layer side and the surface on the reflection layer side), a structure reflecting the step of the dielectric layer can be formed. At this time, the resistance film layer or the reflective layer may not be formed on the raised portion (step surface in the step-terrace structure) of the step.
　本発明のλ／４型電波吸収体の最表面（抵抗膜層側表面及び反射層側の表面の少なくとも一方）においては、誘電体層の段差に他の層が追従して形成される段差が形成され得る。この段差は吸収体厚みを薄くできるという観点から、好ましくは３５０μｍ以下である。本発明のλ／４型電波吸収体は、この表面の段差を利用した各種性質・機能（例えば、表面の意匠性、くぼみによる配線スペース、流滴性等）を備えることができる。この観点からは好ましくは７．５μｍ以上、より好ましくは１５μｍ以上、さらに好ましくは２５μｍ以上、更により好ましくは５０μｍ以上、一層好ましくは１００μｍ以上である。なお、該段差は抵抗膜層側表面及び反射層側表面の両方に形成されていてもよい。 On the outermost surface of the λ / 4 type radio wave absorber of the present invention (at least one of the surface on the resistance film layer side and the surface on the reflection layer side), a step formed by following the step of the dielectric layer by another layer is formed. Can be formed. This step is preferably 350 μm or less from the viewpoint that the thickness of the absorber can be reduced. The λ / 4 type radio wave absorber of the present invention can be provided with various properties / functions (for example, surface design, wiring space due to dents, drip property, etc.) utilizing the step on the surface. From this point of view, it is preferably 7.5 μm or more, more preferably 15 μm or more, still more preferably 25 μm or more, still more preferably 50 μm or more, still more preferably 100 μm or more. The step may be formed on both the resistance film layer side surface and the reflection layer side surface.
　本発明のλ／４型電波吸収体の最表面（抵抗膜層側表面及び反射層側の表面の少なくとも一方）においては、誘電体層の段差に他の層が追従し、上述の誘電体層の厚み差及び構造等が反映された構造が形成され得る。すなわち、本発明のλ／４型電波吸収体は、その最表面（抵抗膜層側表面及び反射層側表面の少なくとも一方）における表面粗さＲｚが７．５μｍ以上であることが好ましい。また、この観点から、本発明は、その一態様において、抵抗膜、誘電体層、及び反射層を含み、最表面（抵抗膜層側表面及び反射層側表面の少なくとも一方）における表面粗さＲｚが７．５μｍ以上である、λ／４型電波吸収体に関する。 On the outermost surface of the λ / 4 type radio wave absorber of the present invention (at least one of the surface on the resistance film layer side and the surface on the reflection layer side), another layer follows the step of the dielectric layer, and the above-mentioned dielectric layer A structure that reflects the difference in thickness and structure of the above can be formed. That is, the λ / 4 type radio wave absorber of the present invention preferably has a surface roughness Rz of 7.5 μm or more on its outermost surface (at least one of the surface on the resistance film layer side and the surface on the reflection layer side). Further, from this viewpoint, in one aspect of the present invention, the present invention includes a resistance film, a dielectric layer, and a reflection layer, and has a surface roughness Rz on the outermost surface (at least one of the surface on the resistance film layer side and the surface on the reflection layer side). The present invention relates to a λ / 4 type radio wave absorber having a thickness of 7.5 μm or more.
　上記Ｒｚはより好ましくは１５μｍ以上、さらに好ましくは２５μｍ以上、更によりに好ましくは５０μｍ以上、特に好ましくは１００μｍ以上である。該Ｒｚの上限は特に限定されないが、吸収体厚みを薄くできるという観点から、好ましくは３５０μｍ以下、より好ましくは２００μｍ以下である。なお、該段差は抵抗膜層側表面及び反射層側表面の両方に形成されていてもよい。
また、抵抗膜、反射膜、誘電体については上述の説明と同様のものを用いることができる。 The Rz is more preferably 15 μm or more, still more preferably 25 μm or more, even more preferably 50 μm or more, and particularly preferably 100 μm or more. The upper limit of the Rz is not particularly limited, but is preferably 350 μm or less, more preferably 200 μm or less, from the viewpoint that the thickness of the absorber can be reduced. The step may be formed on both the resistance film layer side surface and the reflection layer side surface.
Further, as the resistance film, the reflective film and the dielectric, the same ones as described above can be used.
　λ／４型電波吸収体の最表面（抵抗膜層側又は反射層側表面）における表面粗さＲｚは次のように測定することができる。
ＪＩＳ　Ｂ０６０１（２００１）に基づいて、表面粗さ計（株式会社東京精密製、商品名サーフコム１８００Ａ又はその同等品）により測定することができる。 The surface roughness Rz on the outermost surface (the surface on the resistance film layer side or the surface on the reflection layer side) of the λ / 4 type radio wave absorber can be measured as follows.
It can be measured by a surface roughness meter (manufactured by Tokyo Seimitsu Co., Ltd., trade name Surfcom 1800A or its equivalent) based on JIS B0601 (2001).
　＜１－７．製造方法＞
　本発明のλ／４型電波吸収体は、その構成に応じて、様々な方法、例えば公知の製造方法に従って又は準じて得ることができる。例えば、支持体上に抵抗膜、誘電体層、及び反射層を順に積層させる工程を含む方法により、得ることができる。 <1-7. Manufacturing method>
The λ / 4 type radio wave absorber of the present invention can be obtained according to or according to various methods, for example, a known manufacturing method, depending on its configuration. For example, it can be obtained by a method including a step of sequentially laminating a resistance film, a dielectric layer, and a reflective layer on a support.
　積層方法は特に制限されない。 The stacking method is not particularly limited.
　抵抗膜は、例えば、スパッタリング法、真空蒸着法、イオンプレーティング法、化学蒸着法、パルスレーザーデポジション法等により行うことができる。これらの中でも、膜厚制御性の観点から、スパッタリング法が好ましい。スパッタリング法としては、特に限定されないが、例えば、直流マグネトロンスパッタ、高周波マグネトロンスパッタ及びイオンビームスパッタ等が挙げられる。また、スパッタ装置は、バッチ方式であってもロール・ツー・ロール方式であってもよい。 The resistance film can be formed by, for example, a sputtering method, a vacuum vapor deposition method, an ion plating method, a chemical vapor deposition method, a pulse laser deposition method, or the like. Among these, the sputtering method is preferable from the viewpoint of film thickness controllability. The sputtering method is not particularly limited, and examples thereof include DC magnetron sputtering, high frequency magnetron sputtering, and ion beam sputtering. Further, the sputtering apparatus may be a batch system or a roll-to-roll system.
　誘電体層や反射層は、例えば誘電体層が有する粘着性を利用して、積層することができる。 The dielectric layer and the reflective layer can be laminated by utilizing, for example, the adhesiveness of the dielectric layer.
　２．λ／４型電波吸収体部材
　本発明は、その一態様において、抵抗膜及び誘電体層を含み、前記誘電体層が、厚みの差が１５μｍ以上である２つ以上の領域を有する、λ／４型電波吸収体用部材、に関する。λ／４型電波吸収体用部材は好ましくはさらに支持体を含む。λ／４型電波吸収体用部材は、反射層として機能し得る被着体（筐体等）等に接するように配置することによりλ／４型電波吸収体を形成するための部材である。支持体、抵抗膜、誘電体層、その他の構成については、本発明のλ／４型電波吸収体に関する説明と同様である。 2. λ / 4 type radio wave absorber member In one aspect of the present invention, the present invention includes a resistance film and a dielectric layer, and the dielectric layer has two or more regions having a thickness difference of 15 μm or more. It relates to a member for a type 4 radio wave absorber. The member for the λ / 4 type radio wave absorber preferably further includes a support. The λ / 4 type radio wave absorber member is a member for forming a λ / 4 type radio wave absorber by arranging it in contact with an adherend (housing or the like) that can function as a reflective layer. The support, resistance film, dielectric layer, and other configurations are the same as those described for the λ / 4 type radio wave absorber of the present invention.
　３．用途
　本発明のλ／４型電波吸収体は、不要な電磁波を吸収する性能を有するため、例えば光トランシーバや、次世代移動通信システム（５Ｇ）、近距離無線転送技術等における電波対策部材として好適に利用できる。また、その他の用途として自動車、道路、人の相互間で情報通信を行う高度道路交通システム（ＩＴＳ）や自動車衝突防止システムに用いるミリ波レーダーにおいても、電波干渉抑制やノイズ低減の目的で用いることができる。 3. 3. Applications The λ / 4 type radio wave absorber of the present invention has the ability to absorb unnecessary electromagnetic waves, and is therefore suitable as a radio wave countermeasure member in, for example, optical transceivers, next-generation mobile communication systems (5G), short-range wireless transfer technology, and the like. Can be used for. In addition, it should also be used for the purpose of suppressing radio wave interference and reducing noise in intelligent transportation systems (ITS) that communicate information between automobiles, roads, and people, and millimeter-wave radars used in automobile collision prevention systems. Can be done.
　本発明は、その一態様において、成形品と、前記成形品に取り付けられた本発明のλ／４型電波吸収体とを備える、電波吸収体付成形品、に関する。成形品としては、例えば上記各種用途において使用される部材等が挙げられる。本発明のλ／４型電波吸収体を成形品に取り付ける方法としては、特に制限されず、例えば粘着剤を介して取り付ける方法や、固定具により取り付ける方法が挙げられる。電波吸収体付成形品の好ましい一例としては、ミリ波レーダーが挙げられる。 The present invention relates to, in one embodiment, a molded product and a molded product with a radio wave absorber, which comprises the λ / 4 type radio wave absorber of the present invention attached to the molded product. Examples of the molded product include members used in the above-mentioned various uses. The method of attaching the λ / 4 type radio wave absorber of the present invention to the molded product is not particularly limited, and examples thereof include a method of attaching via an adhesive and a method of attaching with a fixture. A preferred example of a molded product with a radio wave absorber is a millimeter wave radar.
　本発明のλ／４型電波吸収体が対象とする電波の周波数は、好ましくは１０ＧＨｚ以上１５０ＧＨｚ以下、より好ましくは２０ＧＨｚ以上１２０ＧＨｚ以下、さらに好ましくは３０ＧＨｚ以上１１０ＧＨｚ以下、さらにより好ましくは５５ＧＨｚ以上１１０ＧＨｚ以下、特に好ましくは５５ＧＨｚ以上９０ＧＨｚ以下、一層好ましくは７０ＧＨｚ以上９０ＧＨｚ以下である。 The frequency of the radio wave targeted by the λ / 4 type radio wave absorber of the present invention is preferably 10 GHz or more and 150 GHz or less, more preferably 20 GHz or more and 120 GHz or less, still more preferably 30 GHz or more and 110 GHz or less, still more preferably 55 GHz or more and 110 GHz or less. It is particularly preferably 55 GHz or more and 90 GHz or less, and more preferably 70 GHz or more and 90 GHz or less.
　本発明のλ／４型電波吸収体は、対象とする電波の照射される範囲内に、上述の誘電体層の厚みの差が１５μｍ以上である２つ以上の領域を有するように設置することが好ましい。また、本発明のλ／４型電波吸収体は対象とする電波の照射される範囲内において、上述する誘電体層の面積平均厚みになるように、各領域の形状や電波吸収体の設置場所を調整することが好ましい。 The λ / 4 type radio wave absorber of the present invention is installed so as to have two or more regions in which the difference in thickness of the above-mentioned dielectric layer is 15 μm or more within the irradiation range of the target radio wave. Is preferable. Further, the λ / 4 type radio wave absorber of the present invention has the shape of each region and the installation location of the radio wave absorber so as to have the area average thickness of the above-mentioned dielectric layer within the range irradiated with the target radio wave. It is preferable to adjust.
　以下に、実施例に基づいて本発明を詳細に説明するが、本発明はこれらの実施例によって限定されるものではない。 Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to these examples.
　（１）λ／４型電波吸収体の製造
　（実施例１）
　まず、誘電体層に使用する粘着テープ（両面粘着テープ）を、次のようにして製造した。幅１０ｃｍ、長さ１０ｃｍ、厚み５００μｍ且つ比誘電率２．５のアクリル両面粘着テープの片面上に、ストライプ状になるように幅１ｃｍ、長さ１０ｃｍ、厚み１００μｍ且つ比誘電率２．５のアクリル両面粘着テープを１ｃｍずつ離間させて積層した。これにより、厚み５００μｍの領域（面積は全体の５０％）と厚み６００μｍの領域（面積は全体の５０％）とからなる粘着テープ（面積平均厚み：５５０μｍ（＝０．５×５００＋０．５×６００））を得た。 (1) Manufacture of λ / 4 type radio wave absorber (Example 1)
First, an adhesive tape (double-sided adhesive tape) used for the dielectric layer was manufactured as follows. Acrylic with a width of 10 cm, a length of 10 cm, a thickness of 500 μm and a relative permittivity of 2.5 on one side of an acrylic double-sided adhesive tape having a width of 1 cm, a length of 10 cm, a thickness of 100 μm and a relative permittivity of 2.5. Double-sided adhesive tapes were laminated with a distance of 1 cm each. As a result, the adhesive tape (area average thickness: 550 μm (= 0.5 × 500 + 0.5 × 600)) is composed of a region having a thickness of 500 μm (area is 50% of the total) and a region having a thickness of 600 μm (area is 50% of the total). )) Was obtained.
　続いて、λ／４型電波吸収体を、次のようにして製造した。支持体として、厚み１２５μｍの白色ポリエチレンテレフタレート（ＰＥＴ）フィルム（比誘電率３．４）を用意した。上記ＰＥＴフィルム上に、ＤＣパルススパッタリングにより、厚み１０ｎｍ且つシート抵抗値３４０Ω／□の抵抗膜を形成した。スパッタリングはハステロイＣ－２７６をターゲットに用い、出力０．４ｋＷ、Ａｒガス流量１００ｓｃｃｍで導入して圧力０．１２Ｐａとなるように調整して行った。次いで、形成した抵抗膜上に、上記粘着テープからなる誘電体層を、段差を有する側を抵抗膜側に向けて、積層し、誘電体層上に厚み１２μｍの銅からなる反射層を積層して、λ／４型電波吸収体を得た。 Subsequently, a λ / 4 type radio wave absorber was manufactured as follows. As a support, a white polyethylene terephthalate (PET) film (relative permittivity 3.4) having a thickness of 125 μm was prepared. A resistance film having a thickness of 10 nm and a sheet resistance value of 340 Ω / □ was formed on the PET film by DC pulse sputtering. Sputtering was carried out using Hastelloy C-276 as a target, introduced at an output of 0.4 kW and an Ar gas flow rate of 100 sccm, and adjusted to a pressure of 0.12 Pa. Next, the dielectric layer made of the adhesive tape was laminated on the formed resistance film with the stepped side facing the resistance film side, and the reflective layer made of copper having a thickness of 12 μm was laminated on the dielectric layer. Then, a λ / 4 type radio wave absorber was obtained.
　（実施例２）
　厚み４００μｍ且つ比誘電率３．６のアクリル両面粘着テープの片面上に、ストライプ状になるように厚み１００μｍ且つ比誘電率３．６のアクリル両面粘着テープを積層した。これにより、厚み４００μｍの領域（面積は全体の５０％）と厚み５００μｍの領域（面積は全体の５０％）とからなる粘着テープ（面積平均厚み：４５０μｍ（＝０．５×４００＋０．５×５００））を得た。得られた粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Example 2)
An acrylic double-sided adhesive tape having a thickness of 100 μm and a relative permittivity of 3.6 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 400 μm and a relative permittivity of 3.6 so as to form a stripe. As a result, the adhesive tape (area average thickness: 450 μm (= 0.5 × 400 + 0.5 × 500)) is composed of a region having a thickness of 400 μm (area is 50% of the total) and a region having a thickness of 500 μm (area is 50% of the total). )) Was obtained. Using the obtained adhesive tape as a dielectric layer, a λ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
　（実施例３）
　厚み４００μｍ且つ比誘電率３．６のアクリル両面粘着テープの片面上に、ストライプ状になるように厚み１００μｍ且つ比誘電率３．６のアクリル両面粘着テープを積層した。このとき、ストライプの幅は積層していない部分と積層した部分の面積比率が１：４になるように積層した。これにより、厚み４００μｍの領域（面積は全体の２０％）と厚み５００μｍの領域（面積は全体の８０％）とからなる粘着テープ（面積平均厚み：４８０μｍ（＝０．２×４００＋０．８×５００））を得た。得られた粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Example 3)
An acrylic double-sided adhesive tape having a thickness of 100 μm and a relative permittivity of 3.6 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 400 μm and a relative permittivity of 3.6 so as to form a stripe. At this time, the width of the stripes was laminated so that the area ratio of the non-laminated portion and the laminated portion was 1: 4. As a result, the adhesive tape (area average thickness: 480 μm (= 0.2 × 400 + 0.8 × 500)) is composed of a region having a thickness of 400 μm (area is 20% of the total) and a region having a thickness of 500 μm (area is 80% of the total). )) Was obtained. Using the obtained adhesive tape as a dielectric layer, a λ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
　（実施例４）
　厚み４００μｍ且つ比誘電率３．６のアクリル両面粘着テープの片面上に、ストライプ状になるように厚み１００μｍ且つ比誘電率３．６のアクリル両面粘着テープを積層した。このとき、ストライプの幅は積層していない部分と積層した部分の比率が４：１になるように積層した。これにより、厚み４００μｍの領域（面積は全体の８０％）と厚み５００μｍの領域（面積は全体の２０％）とからなる粘着テープ（面積平均厚み：４２０μｍ（＝０．８×４００＋０．２×５００））を得た。得られた粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Example 4)
An acrylic double-sided adhesive tape having a thickness of 100 μm and a relative permittivity of 3.6 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 400 μm and a relative permittivity of 3.6 so as to form a stripe. At this time, the width of the stripes was laminated so that the ratio of the non-laminated portion to the laminated portion was 4: 1. As a result, the adhesive tape (area average thickness: 420 μm (= 0.8 × 400 + 0.2 × 500)” is composed of a region having a thickness of 400 μm (area is 80% of the total) and a region having a thickness of 500 μm (area is 20% of the total). )) Was obtained. Using the obtained adhesive tape as a dielectric layer, a λ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
　（実施例５）
　厚み４５０μｍ且つ比誘電率３．０のアクリル両面粘着テープの片面上に、ストライプ状になるように厚み１５０μｍ且つ比誘電率３．０のアクリル両面粘着テープを積層した。これにより、厚み４５０μｍの領域（面積は全体の５０％）と厚み６００μｍの領域（面積は全体の５０％）とからなる粘着テープ（面積平均厚み：５２５μｍ（＝０．５×４５０＋０．５×６００））を得た。得られた粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Example 5)
An acrylic double-sided adhesive tape having a thickness of 150 μm and a relative permittivity of 3.0 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 450 μm and a relative permittivity of 3.0. As a result, the adhesive tape (area average thickness: 525 μm (= 0.5 × 450 + 0.5 × 600)) is composed of a region having a thickness of 450 μm (area is 50% of the total) and a region having a thickness of 600 μm (area is 50% of the total). )) Was obtained. Using the obtained adhesive tape as a dielectric layer, a λ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
　（実施例６）
　厚み４５０μｍ且つ比誘電率３．０のアクリル両面粘着テープの片面上に、ストライプ状になるように厚み１５０μｍ且つ比誘電率３．０のアクリル両面粘着テープを積層した。このとき、ストライプの幅は積層していない部分と積層した部分の面積比率が１：４になるように積層した。これにより、厚み４５０μｍの領域（面積は全体の２０％）と厚み６００μｍの領域（面積は全体の８０％）とからなる粘着テープ（面積平均厚み：５７０μｍ（＝０．２×４５０＋０．８×６００））を得た。得られた粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Example 6)
An acrylic double-sided adhesive tape having a thickness of 150 μm and a relative permittivity of 3.0 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 450 μm and a relative permittivity of 3.0. At this time, the width of the stripes was laminated so that the area ratio of the non-laminated portion and the laminated portion was 1: 4. As a result, the adhesive tape (area average thickness: 570 μm (= 0.2 × 450 + 0.8 × 600)) is composed of a region having a thickness of 450 μm (area is 20% of the total) and a region having a thickness of 600 μm (area is 80% of the total). )) Was obtained. Using the obtained adhesive tape as a dielectric layer, a λ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
　（実施例７）
　厚み４５０μｍ且つ比誘電率３．０のアクリル両面粘着テープの片面上に、ストライプ状になるように厚み１５０μｍ且つ比誘電率３．０のアクリル両面粘着テープを積層した。このとき、ストライプの幅は積層していない部分と積層した部分の比率が４：１になるように積層した。これにより、厚み４５０μｍの領域（面積は全体の８０％）と厚み６００μｍの領域（面積は全体の２０％）とからなる粘着テープ（面積平均厚み：４８０μｍ（＝０．８×４５０＋０．２×６００））を得た。得られた粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Example 7)
An acrylic double-sided adhesive tape having a thickness of 150 μm and a relative permittivity of 3.0 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 450 μm and a relative permittivity of 3.0. At this time, the width of the stripes was laminated so that the ratio of the non-laminated portion to the laminated portion was 4: 1. As a result, the adhesive tape (area average thickness: 480 μm (= 0.8 × 450 + 0.2 × 600)) is composed of a region having a thickness of 450 μm (area is 80% of the total) and a region having a thickness of 600 μm (area is 20% of the total). )) Was obtained. Using the obtained adhesive tape as a dielectric layer, a λ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
　（実施例８）
　厚み３０μｍ且つ比誘電率３．０のアクリル両面粘着テープの片面上に、厚み４００μｍ且つ比誘電率２．６のポリカーボネートからなる誘電体と、厚み５００μｍ且つ比誘電率２．６のポリカーボネートからなる誘電体とを、ストライプ状になるように交互に並べた。さらにその上に厚み３０μｍ且つ比誘電率３．０のアクリル両面粘着テープを積層して、厚み４６０μｍの領域（面積は全体の５０％）と厚み５６０μｍの領域（面積は全体の５０％）とからなるポリカーボネートからなる誘電体（面積平均厚み：５１０μｍ（＝０．５×４６０＋０．５×５６０））を得た。得られた粘着テープを有する誘電体を誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Example 8)
A dielectric made of polycarbonate having a thickness of 400 μm and a relative permittivity of 2.6 and a dielectric made of polycarbonate having a thickness of 500 μm and a relative permittivity of 2.6 on one side of an acrylic double-sided adhesive tape having a thickness of 30 μm and a relative permittivity of 3.0. The bodies were arranged alternately in a striped pattern. Further, an acrylic double-sided adhesive tape having a thickness of 30 μm and a relative permittivity of 3.0 is laminated on it, and a region having a thickness of 460 μm (area is 50% of the total) and a region having a thickness of 560 μm (area is 50% of the total) are formed. Dielectric material (area average thickness: 510 μm (= 0.5 × 460 + 0.5 × 560)) made of polycarbonate was obtained. Using the obtained dielectric having the adhesive tape as the dielectric layer, a λ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
　（実施例９）
　厚み４８５μｍ且つ比誘電率２．５のアクリル両面粘着テープの片面上に、ストライプ状になるように厚み１５μｍ且つ比誘電率２．５のアクリル両面粘着テープを積層した。このとき、ストライプの幅は積層していない部分と積層した部分の比率が１：１になるように積層した。これにより、厚み４８５μｍの領域（面積は全体の５０％）と厚み５００μｍの領域（面積は全体の５０％）とからなる粘着テープ（面積平均厚み：４９２．５μｍ（＝０．５×４８５＋０．５×５００））を得た。得られた粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Example 9)
An acrylic double-sided adhesive tape having a thickness of 15 μm and a relative permittivity of 2.5 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 485 μm and a relative permittivity of 2.5 so as to form a stripe. At this time, the width of the stripes was laminated so that the ratio of the non-laminated portion and the laminated portion was 1: 1. As a result, the adhesive tape (area average thickness: 492.5 μm (= 0.5 × 485 + 0.5)) is composed of a region having a thickness of 485 μm (area is 50% of the total) and a region having a thickness of 500 μm (area is 50% of the total). × 500)) was obtained. Using the obtained adhesive tape as a dielectric layer, a λ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
　（実施例１０）
　厚み３５０μｍ且つ比誘電率２．５のアクリル両面粘着テープの片面上に、ストライプ状になるように厚み３５０μｍ且つ比誘電率２．５のアクリル両面粘着テープを積層した。このとき、ストライプの幅は積層していない部分と積層した部分の比率が１：１になるように積層した。これにより、厚み３５０μｍの領域（面積は全体の５０％）と厚み７００μｍの領域（面積は全体の５０％）とからなる粘着テープ（面積平均厚み：５２５μｍ（＝０．５×３５０＋０．５×７００））を得た。得られた粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Example 10)
An acrylic double-sided adhesive tape having a thickness of 350 μm and a relative permittivity of 2.5 was laminated on one side of an acrylic double-sided adhesive tape having a thickness of 350 μm and a relative permittivity of 2.5 so as to form a stripe. At this time, the width of the stripes was laminated so that the ratio of the non-laminated portion and the laminated portion was 1: 1. As a result, the adhesive tape (area average thickness: 525 μm (= 0.5 × 350 + 0.5 × 700)) is composed of a region having a thickness of 350 μm (area is 50% of the total) and a region having a thickness of 700 μm (area is 50% of the total). )) Was obtained. Using the obtained adhesive tape as a dielectric layer, a λ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
　（実施例１１）
　厚み３０μｍ且つ比誘電率３．０のアクリル両面粘着テープの片面上に、厚み３００μｍ且つ比誘電率２．６のポリカーボネートからなる誘電体と、厚み５００μｍ且つ比誘電率２．６のポリカーボネートからなる誘電体とを、１０ｍｍ角の小片状にカットした後、市松模様になるように交互に並べた。さらにその上に厚み３０μｍ且つ比誘電率３．０のアクリル両面粘着テープを積層して、厚み３６０μｍの領域（面積は全体の５０％）と厚み５６０μｍの領域（面積は全体の５０％）とからなる誘電体（面積平均厚み：４６０μｍ（＝０．５×３６０＋０．５×５６０））を得た。得られた粘着テープを有する誘電体を誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Example 11)
A dielectric made of polycarbonate having a thickness of 300 μm and a relative permittivity of 2.6 and a dielectric made of polycarbonate having a thickness of 500 μm and a relative permittivity of 2.6 on one side of an acrylic double-sided adhesive tape having a thickness of 30 μm and a relative permittivity of 3.0. After cutting the body into small pieces of 10 mm square, they were arranged alternately in a checkered pattern. Further, an acrylic double-sided adhesive tape having a thickness of 30 μm and a relative permittivity of 3.0 is laminated on the tape, and the region has a thickness of 360 μm (the area is 50% of the total) and the region has a thickness of 560 μm (the area is 50% of the total). Dielectric material (area average thickness: 460 μm (= 0.5 × 360 + 0.5 × 560)) was obtained. Using the obtained dielectric having the adhesive tape as the dielectric layer, a λ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
　（実施例１２）
　厚み３０μｍ且つ比誘電率３．０のアクリル両面粘着テープの片面上に、厚み２００μｍ且つ比誘電率２．６のポリカーボネートからなる誘電体と、厚み３００μｍ且つ比誘電率２．６のポリカーボネートからなる誘電体と、厚み４００μｍ且つ比誘電率２．６のポリカーボネートからなる誘電体と、厚み５００μｍ且つ比誘電率２．６のポリカーボネートからなる誘電体とを、５０ｍｍ角にカットした後、各厚み１枚ずつを用いて１００ｍｍの正方形になるように並べた。さらにその上に厚み３０μｍ且つ比誘電率３．０のアクリル両面粘着テープを積層して、厚み２６０μｍの領域（面積は全体の２５％）と厚み３６０μｍの領域（面積は全体の２５％）と厚み４６０μｍの領域（面積は全体の２５％）と厚み５６０μｍの領域（面積は全体の２５％）からなる誘電体（面積平均厚み：４１０μｍ（＝０．２５×２６０＋０．２５×３６０＋０．２５×４６０＋０．２５×５６０））を得た。得られた粘着テープを有する誘電体を誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Example 12)
On one side of an acrylic double-sided adhesive tape with a thickness of 30 μm and a relative permittivity of 3.0, a dielectric made of polycarbonate having a thickness of 200 μm and a relative dielectric constant of 2.6 and a dielectric made of polycarbonate having a thickness of 300 μm and a relative dielectric constant of 2.6 After cutting the body, a dielectric made of polycarbonate having a thickness of 400 μm and a relative permittivity of 2.6, and a dielectric made of polycarbonate having a thickness of 500 μm and a relative permittivity of 2.6 into 50 mm squares, one piece each having a thickness of 50 mm square. Was arranged so as to form a 100 mm square. Furthermore, an acrylic double-sided adhesive tape with a thickness of 30 μm and a relative permittivity of 3.0 is laminated on it, and a region with a thickness of 260 μm (area is 25% of the total), a region with a thickness of 360 μm (area is 25% of the total), and a thickness. Dielectric (area average thickness: 410 μm (= 0.25 × 260 + 0.25 × 360 + 0.25 × 460 + 0.) Consisting of a region of 460 μm (area is 25% of the total) and a region of thickness 560 μm (area is 25% of the total). 25 × 560))) was obtained. Using the obtained dielectric having the adhesive tape as the dielectric layer, a λ / 4 type radio wave absorber was obtained in the same manner as in Example 1.
　（比較例１）
　厚み４００μｍ且つ比誘電率３．６の段差の無いアクリル両面粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Comparative Example 1)
An acrylic double-sided adhesive tape having a thickness of 400 μm and a relative permittivity of 3.6 and having no step was used as the dielectric layer to obtain a λ / 4 type radio wave absorber in the same manner as in Example 1.
　（比較例２）
　厚み５００μｍ且つ比誘電率３．６の段差の無いアクリル両面粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Comparative Example 2)
An acrylic double-sided adhesive tape having a thickness of 500 μm and a relative permittivity of 3.6 and having no step was used as the dielectric layer to obtain a λ / 4 type radio wave absorber in the same manner as in Example 1.
　（比較例３）
　厚み４００μｍ且つ比誘電率２．６の段差の無いポリカーボネートの両面に厚み３０μｍ且つ比誘電率３．０のアクリル両面粘着テープを積層した粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Comparative Example 3)
An adhesive tape in which an acrylic double-sided adhesive tape having a thickness of 30 μm and a relative permittivity of 3.0 is laminated on both sides of a polycarbonate having a thickness of 400 μm and a relative permittivity of 2.6 without a step is used as a dielectric layer in the same manner as in Example 1. A λ / 4 type radio wave absorber was obtained.
　（比較例４）
　厚み５００μｍ且つ比誘電率２．６の段差の無いポリカーボネートの両面に厚み３０μｍ且つ比誘電率３．０のアクリル両面粘着テープを積層した粘着テープを誘電体層として用いて、実施例１と同様にして、λ／４型電波吸収体を得た。 (Comparative Example 4)
An adhesive tape in which an acrylic double-sided adhesive tape having a thickness of 30 μm and a relative permittivity of 3.0 is laminated on both sides of a polycarbonate having a thickness of 500 μm and a relative permittivity of 2.6 without a step is used as a dielectric layer in the same manner as in Example 1. A λ / 4 type radio wave absorber was obtained.
　Ｒｚの測定
　得られたλ／４型電波吸収体の段差を有する表面について、ＪＩＳ　Ｂ０６０１（２００１）に基づいて、表面粗さ計（株式会社東京精密製、商品名サーフコム１８００Ａ　）によりＲｚの測定を行った。 Measurement of Rz For the surface of the obtained λ / 4 type radio wave absorber with a step, measure Rz with a surface roughness meter (manufactured by Tokyo Seimitsu Co., Ltd., trade name: Surfcom 1800A) based on JIS B0601 (2001). went.
　（２）電波吸収量及び電波吸収ピーク位置の測定
　ネットワークアナライザー　ＭＳ４６４７Ｂ（アンリツ社製）、フリースペース材料測定装置　ＢＤ１－２６．Ａ（キーコム社製）を用いて電波吸収測定装置を構成した。この電波吸収測定装置を用いて、得られたλ／４型電波吸収体の５５～９０ＧＨｚ帯での電波吸収量をＪＩＳ　Ｒ１６７９に基づいて測定した。なお、λ／４型電波吸収体は、電波入射方向垂直、かつ支持体側（抵抗膜側）からの入射となるようにセットした。得られた吸収量について、吸収ピークの周波数及び吸収ピークでの吸収量を評価した。 (2) Measurement of radio wave absorption amount and radio wave absorption peak position Network analyzer MS4647B (manufactured by Anritsu), free space material measuring device BD1-26. A radio wave absorption measuring device was constructed using A (manufactured by Keycom). Using this radio wave absorption measuring device, the amount of radio wave absorption in the 55 to 90 GHz band of the obtained λ / 4 type radio wave absorber was measured based on JIS R1679. The λ / 4 type radio wave absorber was set so as to be perpendicular to the radio wave incident direction and to be incident from the support side (resistive film side). Regarding the obtained absorption amount, the frequency of the absorption peak and the absorption amount at the absorption peak were evaluated.
　（３）結果
　結果を表１～４に示す。 (3) Results The results are shown in Tables 1 to 4.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　実施例１～８のλ／４型電波吸収体は、誘電体層が比較的大きな段差を有するにもかかわらず、目的の波長範囲において良好な電波吸収特性を発揮した。 The λ / 4 type radio wave absorbers of Examples 1 to 8 exhibited good radio wave absorption characteristics in a target wavelength range even though the dielectric layer had a relatively large step.
　また、さらに解析を進めた結果、段差を設けた場合の電波吸収ピーク位置は、段差を有する誘電体層の面積平均厚みを誘電体層の厚みとみなして算出される電波吸収ピーク位置にほぼ一致すること、すなわち、段差を設けた場合の電波吸収ピーク位置は、誘電体層の厚い領域と薄い領域のそれぞれの厚みとそれらの面積比に基づいて制御できることが分かった。 Further, as a result of further analysis, the radio wave absorption peak position when the step is provided almost coincides with the radio wave absorption peak position calculated by regarding the area average thickness of the dielectric layer having the step as the thickness of the dielectric layer. That is, it was found that the radio wave absorption peak position when the step is provided can be controlled based on the respective thicknesses of the thick region and the thin region of the dielectric layer and their area ratios.
　さらに、実施例１～８のλ／４型電波吸収体は、誘電体層の段差に追従して、支持体側表面上に段差が形成されていた。このことから、誘電体層に積極的に段差を設ける場合、表面の段差を利用した各種性質・機能（例えば、表面の意匠性、くぼみによる配線スペース、流滴性等）を付与し得ることが分かった。 Further, in the λ / 4 type radio wave absorbers of Examples 1 to 8, a step was formed on the surface on the support side following the step of the dielectric layer. From this, when the dielectric layer is positively provided with a step, various properties and functions (for example, surface design, wiring space due to dents, drip property, etc.) can be imparted by utilizing the step on the surface. Do you get it.
１　　抵抗膜
２　　誘電体層
３　　反射層
４　　筐体
５　　粘着層
６　　成形品 1 Resistive film 2 Dielectric layer 3 Reflective layer 4 Housing 5 Adhesive layer 6 Molded product

Claims (9)

  1. 抵抗膜、誘電体層、及び反射層を含み、前記誘電体層が、厚みの差が１５μｍ以上である２つ以上の領域を有する、λ／４型電波吸収体。 A λ / 4 type radio wave absorber including a resistance film, a dielectric layer, and a reflective layer, wherein the dielectric layer has two or more regions having a thickness difference of 15 μm or more.
  2. 前記厚みの差が３５０μｍ以下である、請求項１に記載のλ／４型電波吸収体。 The λ / 4 type radio wave absorber according to claim 1, wherein the difference in thickness is 350 μm or less.
  3. 前記２つ以上の各領域の厚みが、前記誘電体層の面積平均厚み１００％に対して、８０～１２０％である、請求項１又は２に記載のλ／４型電波吸収体。 The λ / 4 type radio wave absorber according to claim 1 or 2, wherein the thickness of each of the two or more regions is 80 to 120% with respect to 100% of the area average thickness of the dielectric layer.
  4. 前記誘電体層の面積平均厚みが１００～８００μｍである、請求項１～３のいずれかに記載のλ／４型電波吸収体。 The λ / 4 type radio wave absorber according to any one of claims 1 to 3, wherein the area average thickness of the dielectric layer is 100 to 800 μm.
  5. ６０～９０ＧＨｚにおける電波吸収量が１５ｄＢ以上である、請求項１～４のいずれかに記載のλ／４型電波吸収体。 The λ / 4 type radio wave absorber according to any one of claims 1 to 4, wherein the radio wave absorption amount at 60 to 90 GHz is 15 dB or more.
  6. 抵抗膜、誘電体層、及び反射層を含み、前記抵抗膜層側表面及び前記反射層側表面のうち少なくとも一方におけるＲｚが７．５μｍ以上である、λ／４型電波吸収体。 A λ / 4 type radio wave absorber including a resistance film, a dielectric layer, and a reflection layer, and having an Rz of 7.5 μm or more on at least one of the resistance film layer side surface and the reflection layer side surface.
  7. 成形品と、前記成形品に取り付けられた請求項１～５のいずれかに記載のλ／４型電波吸収体とを備える、電波吸収体付成形品。 A molded product with a radio wave absorber, comprising the molded product and the λ / 4 type radio wave absorber according to any one of claims 1 to 5 attached to the molded product.
  8. ミリ波レーダーである、請求項６に記載の電波吸収体付成形品。 The molded product with a radio wave absorber according to claim 6, which is a millimeter wave radar.
  9. 抵抗膜及び誘電体層を含み、前記誘電体層が、厚みの差が１５μｍ以上である２つ以上の領域を有する、λ／４型電波吸収体用部材。 A λ / 4 type radio wave absorber member including a resistance film and a dielectric layer, wherein the dielectric layer has two or more regions having a thickness difference of 15 μm or more.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5927597A (en) * 1982-08-06 1984-02-14 ティーディーケイ株式会社 Radio wave absorber
JPH0384997A (en) * 1989-08-28 1991-04-10 Akzo Kashima Ltd Electromagnetic wave absorber
JPH057093A (en) * 1991-06-28 1993-01-14 Osaka Gas Co Ltd Radio wave absorber
JP2002176285A (en) * 2000-12-05 2002-06-21 Em Techno:Kk Radio wave absorbing body and method therefor
JP2009193739A (en) * 2008-02-13 2009-08-27 Mitsubishi Paper Mills Ltd Conductive material precursor and electrically conductive material

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5927597A (en) * 1982-08-06 1984-02-14 ティーディーケイ株式会社 Radio wave absorber
JPH0384997A (en) * 1989-08-28 1991-04-10 Akzo Kashima Ltd Electromagnetic wave absorber
JPH057093A (en) * 1991-06-28 1993-01-14 Osaka Gas Co Ltd Radio wave absorber
JP2002176285A (en) * 2000-12-05 2002-06-21 Em Techno:Kk Radio wave absorbing body and method therefor
JP2009193739A (en) * 2008-02-13 2009-08-27 Mitsubishi Paper Mills Ltd Conductive material precursor and electrically conductive material

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