Radio wave absorbing sheet making kit and radio wave absorbing sheet

Abstract

The objective is to provide radio wave absorbing products that offer superior convenience. [Solution] A radio wave absorbing sheet manufacturing kit is provided, comprising a resistive layer component, a metal layer component, and a dielectric layer component, wherein the resistive layer component, the metal layer component, and the dielectric layer component are separated from each other, the resistive layer component has a resistive layer, the metal layer component has a metal layer, and the dielectric layer component has a pair of dielectric layers separated from each other, and the resistive layer component, the metal layer component, and the dielectric layer component are configured to be stacked in close contact.

Description

Technical Field

[0001] The present invention relates to a radio wave absorption sheet production kit and a radio wave absorption sheet.

Background Art

[0002] In Patent Document 1, a radio wave absorber that suppresses and absorbs reflection of unnecessary radio waves has been proposed. In the radio wave absorber of Patent Document 1, a resistance layer is provided on the surface of the dielectric layer on the radio wave incident side, and a reflection layer that reflects radio waves is provided on the opposite back surface. This radio wave absorber is a radio wave interference type radio wave absorber that absorbs radio waves by interfering and canceling out the radio waves reflected by the resistance layer and the radio waves reflected by the reflection layer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In conventional radio wave absorbers, each product is provided for use in a specific frequency band. The use (corresponding frequency) is determined for each product, and there is a problem of low convenience for users.

[0005] An object of the present invention is to provide a radio wave absorber product with excellent convenience.

Means for Solving the Problems

[0006] It should be noted that there is an incorrect tag "<� " in the original text, which is retained as it is in the translation. If this is an actual error, it may need to be corrected in the original source for a more accurate translation.According to the present invention, a radio wave absorbing sheet manufacturing kit is provided, comprising a resistive layer component, a metal layer component, and a dielectric layer component, wherein the resistive layer component, the metal layer component, and the dielectric layer component are separated from each other, the resistive layer component has a resistive layer, the metal layer component has a metal layer, and the dielectric layer component has a pair of dielectric layers separated from each other, and the resistive layer component, the metal layer component, and the dielectric layer component are configured to be stacked in close contact.

[0007] According to the present invention, the applicable frequency band can be selected depending on how the components of the radio wave absorbing sheet fabrication kit are combined, thereby improving user convenience. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1A is a schematic cross-sectional view showing each component of the radio wave absorbing sheet fabrication kit 100 according to the embodiment. Figure 1B shows (a) an example of a planar structure of the resistive layer RR, and (b) an example of a planar structure of the resistive layer RR different from (a). [Figure 2] Figure 2A shows radio wave absorbing sheet 100A, Figure 2B shows radio wave absorbing sheet 100B, Figure 2C shows radio wave absorbing sheet 100C, Figure 2D shows radio wave absorbing sheet 100D, Figure 2E shows radio wave absorbing sheet 100E, and Figure 2F shows radio wave absorbing sheet 100F. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. The various features shown in the embodiments below can be combined with each other. Furthermore, each feature constitutes an independent invention. It should be noted that, for convenience, the terms "front face" and "rear face" may be used in the description of the embodiments to distinguish between them. However, this is merely a convenient distinction in the embodiments, and it simply means that if one side is the front face, the opposite side is the rear face. The designation of the front face and rear face in the embodiments is merely an example for explanation purposes and is not limiting; the designation of the front face and rear face is interchangeable. Also, the size of the components shown in the figures, especially the thickness of each layer, is not necessarily representative of reality, and the present invention is not limited by the dimensions of the illustrated configuration.

[0010] 1. Radio wave absorbing sheet fabrication kit of the embodiment 1-1. Components of the radio wave absorbing sheet fabrication kit The radio wave absorbing sheet fabrication kit 100 of this embodiment includes, as an example, a resistive layer component R, metal layer components M1 and M2, and dielectric layer components D1 to D3. Figure 1A shows a cross-sectional view of each component (resistive layer component R, metal layer components M1 and M2, and dielectric layer components D1 to D3). In reality, each component can be provided in the form of a sheet of any size and can have a certain degree of spread in the direction of the sheet surface. The resistive layer component R, metal layer components M1 and M2, and dielectric layer components D1 to D3 are separated from each other, and this set is provided as the radio wave absorbing sheet fabrication kit 100.

[0011] The resistive layer component R has a resistive layer RR. The resistive layer RR has functions related to the reflection and transmission of radio waves. The resistive layer RR can reflect a portion of the incident radio waves and allow the remaining radio waves to pass through.

[0012] Metal layer components M1 and M2 each have metal layers MM1 and MM2, respectively. In the radio wave absorbing sheets 100A to 100F (see Figures 2A to 2F), metal layers MM1 and MM2 are configured to reflect radio waves that have passed through the resistive layer RR. In other words, metal layers MM1 and MM2 are "reflective layers" that reflect radio waves that have passed through all of the dielectric and resistive layers. Unlike the resistive layer RR, metal layers MM1 and MM2 do not need to pass radio waves through, so they can have as low a resistance value as possible.

[0013] Dielectric layer component D1 has a pair of dielectric layers D1f and D1r that are separated from each other. Dielectric layer component D2 has a pair of dielectric layers D2f and D2r that are separated from each other. Dielectric layer component D3 has a pair of dielectric layers D3f and D3r that are separated from each other. The resistive layer component R, metal layer components M1 and M2, and dielectric layer components D1 to D3 are configured to be stacked in close contact. Several examples of specific stacking patterns will be explained later using Figure 2.

[0014] In this embodiment, for example, dielectric layer component D1 is provided for the 300 GHz band, dielectric layer component D2 is provided for the 150 GHz band, and dielectric layer component D3 is provided for the 77 GHz band.

[0015] The resistive layer component R further comprises a pair of resistive layer component dielectric layers DR1. The resistive layer RR is located between the pair of resistive layer component dielectric layers DR1.

[0016] Metal layer component M1 further comprises a pair of metal layer component dielectric layers DM1. Metal layer MM1 is disposed between the pair of metal layer component dielectric layers DM1. Metal layer component M2 further comprises a pair of metal layer component dielectric layers DM2. Metal layer MM2 is disposed between the pair of metal layer component dielectric layers DM2.

[0017] In one embodiment, for example, metal layer component M1 is provided for an incident angle of 45 degrees, and metal layer component M2 is provided for an incident angle of 0 degrees. This is just an example, and multiple different metal layer components may be provided for any incident angle (e.g., any angle from 0 to 45 degrees).

[0018] In an embodiment, at least one of the resistance layer component R and the dielectric layer components D1 to D3 may further include an adhesive layer (not shown) for adhering them to each other.

[0019] In an embodiment, at least one of the metal layer components M1, M2 and the dielectric layer components D1 to D3 may further include an adhesive layer (not shown) for adhering them to each other.

[0020] 2. Usage mode of the embodiment (radio wave absorbing sheet) 2-1. Overview As illustrated in FIGS. 2A to 2F, according to the embodiment, it is possible to provide radio wave absorbing sheets 100A to 100F using a radio wave absorbing sheet production kit 100. Each of the radio wave absorbing sheets 100A to 100F includes one dielectric layer (dielectric layer D1f, D2f or D3f) of the dielectric layer components D1 to D3, a resistance layer component R, the other dielectric layer (dielectric layer D1r, D2r or D3r) of the dielectric layer components D1 to D3, and a metal layer component M1 or M2. By laminating these layers in this order from the radio wave incident side, the radio wave absorbing sheets 100A to 100F are formed.

[0021] Each figure is a figure described to facilitate understanding of the configuration of each radio wave absorbing sheet 100A to 100F. Regarding the size of the members shown in the figure, particularly the thickness of each layer, it is not necessarily represented in accordance with reality, and the present invention is not limited by the dimensions of the illustrated configuration.

[0022] Each of the radio wave absorbing sheets 100A to 100F is, as an example, a sheet-like member and is configured to absorb radio waves. Each of the radio wave absorbing sheets 100A to 100F may be formed to have flexibility as a whole. Each of the radio wave absorbing sheets 100A to 100F may further have another layer member (for example, a reinforcing member for reinforcing each of the radio wave absorbing sheets 100A to 100F, etc.).

[0023] Each of the radio wave absorption sheets 100A to 100F can be provided as, for example, a radio wave interference type (also referred to as λ / 4 type or reflection type) radio wave absorption sheet. The radio wave interference type absorption sheet can be configured, for example, such that the thickness d of the dielectric layer of a dielectric having a dielectric constant ε is set to d = λ / 4 = πc / (2ω√ε) according to the wavelength λ (= 1 / frequency) of the radio wave to be absorbed during propagation in the dielectric.

[0024] 2-2. Combination pattern The radio wave absorption sheet 100A (an example of a 300 GHz band absorber) in FIG. 2A sandwiches both sides of the resistance layer component R between a pair of dielectric layers D1f and D1r of the dielectric layer component D1, and a metal layer component M1 is overlaid on the outer surface of the dielectric layer D1r, and these are integrated. The integration can arbitrarily employ adhesion via an adhesive layer or the like.

[0025] The radio wave absorption sheet 100B (an example of a 150 GHz band absorber) in FIG. 2B sandwiches both sides of the resistance layer component R between a pair of dielectric layers D2f and D2r of the dielectric layer component D2, and a metal layer component M1 is overlaid on the outer surface of the dielectric layer D2r, and these are integrated.

[0026] The radio wave absorption sheet 100C (an example of a 77 GHz band absorber) in FIG. 2C sandwiches both sides of the resistance layer component R between a pair of dielectric layers D3f and D3r of the dielectric layer component D3, and a metal layer component M1 is overlaid on the outer surface of the dielectric layer D3r, and these are integrated.

[0027] The radio wave absorption sheet 100D (an example of a 300 GHz band absorber) in FIG. 2D sandwiches both sides of the resistance layer component R between a pair of dielectric layers D1f and D1r of the dielectric layer component D1, and a metal layer component M2 is overlaid on the outer surface of the dielectric layer D1r, and these are integrated.

[0028] The radio wave absorption sheet 100E (an example of a 150 GHz band absorber) in FIG. 2E sandwiches both sides of the resistance layer component R between a pair of dielectric layers D2f and D2r of the dielectric layer component D2, and a metal layer component M2 is overlaid on the outer surface of the dielectric layer D2r, and these are integrated.

[0029] The radio wave absorbing sheet 100F in Figure 2F (an example of a 77GHz band absorber) is constructed by sandwiching both sides of a resistive layer component R between a pair of dielectric layers D3f and D3r of a dielectric layer component D3, and then stacking a metal layer component M2 on the outer surface of the dielectric layer D3r, thereby integrating these components.

[0030] 3. Specific composition of each layer (materials, properties, thickness, etc.) 3-1. Dielectric layer configuration of each component As described above, each component of the radio wave absorbing sheet fabrication kit 100 is equipped with a dielectric layer. Specifically, the dielectric layer of each component includes the dielectric layer DR1 of each resistive layer component R, the dielectric layers DM1 and DM2 of each metal layer component M1 and M2, and the dielectric layers D1f to D3r of each dielectric layer component D1 to D3. Various dielectric materials can be used for each of these dielectric layers (DR1, DM1, DM2, D1f to D3r). Each dielectric layer (DR1, DM1, DM2, D1f to D3r) can be configured to include a polymer material. This polymer material may be, for example, synthetic resins (including thermoplastic elastomers) such as polyvinyl chloride, polyvinylidene fluoride, acrylic resin, ethylene vinyl acetate copolymer, polyurethane, acrylic urethane resin, ionomer, polyolefin, polypropylene, polyethylene, silicone resin, polyester, polystyrene, polyimide, polyamide, polysulfone, polyethersulfone, and epoxy resin, or synthetic rubbers such as polyisoprene rubber, polystyrene-butadiene rubber, polybutadiene rubber, chloroprene rubber, acrylonitrile butadiene rubber, butyl rubber, acrylic rubber, ethylene propylene rubber, and silicone rubber. These may be used alone or in combination of two or more to constitute the polymer material.

[0031] Furthermore, each dielectric layer (DR1, DM1, DM2, D1f~D3r) may be composed of materials such as glass, titanium oxide, alumina, and barium titanate.

[0032] Each dielectric layer (DR1, DM1, DM2, D1f~D3r) may be composed of the same dielectric material or different dielectric materials. Furthermore, each dielectric layer (DR1, DM1, DM2, D1f~D3r) may be composed of multiple dielectric layers stacked on top of each other. Also, the thickness of each dielectric layer (DR1, DM1, DM2, D1f~D3r) may be the same or different. In addition, each dielectric layer (DR1, DM1, DM2, D1f~D3r) may have an adhesive layer formed on its surface facing the radio wave incidence side. In other words, each dielectric layer (DR1, DM1, DM2, D1f~D3r) may include an adhesive layer, and the dielectric layers and adhesive layers do not necessarily have to be considered as separate components.

[0033] The relative permittivity of each dielectric layer (DR1, DM1, DM2, D1f~D3r) can be set as appropriate. Specifically, for example, these could be 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10, and may also be within the range of any two of the values ​​exemplified here. The relative permittivity of each dielectric layer (DR1, DM1, DM2, D1f~D3r) may be the same or different. In the layer structure of each radio wave absorbing sheet 100A~100F, the dielectric layers (DR1, DM1, DM2, D1f~D3r) may be set such that the relative permittivity of two adjacent dielectric layers is the same or the difference between them is within a certain range.

[0034] Let p1 be the dielectric constant of the dielectric layer DR1 of each resistive layer component, and let s be the dielectric constant of the dielectric layers D1f, D1r, D2f, D2r, D3f, D3r of each dielectric layer component D1 to D3. Then the following equation may satisfy 0.9 × s ≤ p1 ≤ 1.1 × s. Here, if k1 and k2 are coefficients, then the following equation may satisfy k1 × s ≤ p1 ≤ k2 × s. k1 may be, for example, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, or 0.99, and may be within the range between any two of the values ​​exemplified here. k2 may be, for example, 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, or 1.1, and may be within the range between any two of the values ​​exemplified here.

[0035] Let p2 be the dielectric constant of the dielectric layers DM1 and DM2 of each metal layer component, and let s be the dielectric constant of the dielectric layers D1f, D1r, D2f, D2r, D3f, and D3r of the dielectric layer components D1 to D3. Then the condition 0.9 × s ≤ p2 ≤ 1.1 × s may be satisfied. Here, if k3 and k4 are coefficients, then the condition k3 × s ≤ p2 ≤ k4 × s may be satisfied. k3 can be the numerical value or range exemplified in k1 above, and k4 can be the numerical value or range exemplified in k2 above. However, k3, k4 and k1, k2 may be the same value or different values.

[0036] The thickness (μm) of each dielectric layer (DR1, DM1, DM2, D1f~D3r) can be, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, and may be within the range of any two of the values ​​exemplified here.

[0037] In one embodiment, for example, among dielectric layer components D1 to D3, the thicknesses of dielectric layers D1f and D1r are the minimum, the thicknesses of dielectric layers D3f and D3r are the maximum, and the thicknesses of dielectric layers D2f and D2r are intermediate in thickness. Specifically, the thickness of each dielectric layer D2f and D2r may be, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, or 6.0 times the thickness of each dielectric layer D1f and D1r, or it may be within the range of any two of the values ​​exemplified here. Furthermore, the thickness of each dielectric layer D3f and D3r may be, specifically, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, or 6.0 times the thickness of each dielectric layer D2f and D2r, or within the range of any two of the values ​​exemplified here.

[0038] 3-2.Resistance layer As the resistive layer RR in the resistive layer component R, various known resistive layers can be arbitrarily adopted. In the embodiment, as examples of specific configurations, "First Example (First Resistive Layer RR)" and "Second Example (Second Resistive Layer RR)" will be described. In the embodiment, as an example, either "First Resistive Layer RR" or "Second Resistive Layer RR" can be arbitrarily adopted as the resistive layer RR. Alternatively, although only one resistive layer component R is shown in Figure 1A, other resistive layer components may be added, and one of these two may adopt the configuration of "First Resistive Layer RR" and the other may adopt the configuration of "Second Resistive Layer RR".

[0039] 3-2-1. First resistive layer RR As shown in Figure 1B, the first resistive layer RR can, for example, employ a periodic structure 1RS. This periodic structure 1RS is formed to have periodicity within the plane of the first resistive layer RR so as to pass through a predetermined range of frequencies. In other words, the first resistive layer RR can, for example, employ a structure with a frequency-selective surface (patch-type resonator structure).

[0040] Here, the predetermined frequency range through which the first resistive layer RR passes specifically includes, for example, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 400, and 500, and may also include the range between any two of the values ​​exemplified here. Note that the predetermined frequency range through which the resistive layer RR in the first example passes may be divided into multiple frequency ranges. For example, if defined using the values ​​listed above, it could be a frequency range of 10 GHz or more and 40 GHz or less, and a frequency range of 80 GHz or more and 120 GHz or less.

[0041] The shape of the periodic structure 1RS is not particularly limited. For example, as shown in Figure 1B(a), the periodic structure 1RS can be composed of a plurality of resistive element portions 1Ra arranged to have periodicity in the plane of the first resistive layer RR. In the example shown in Figure 1B(a), the resistive element portion 1Ra is shown as a circular ring shape, but it is not limited to this, and may have other shapes such as rectangular.

[0042] As shown in Figure 1B(b), the periodic structure 1RS can extend across the entire area of ​​the first resistive layer RR and be composed of a periodic mesh structure. Thus, the shape of the periodic structure 1RS is not particularly limited.

[0043] Furthermore, the periodicity of the periodic structure 1RS may exist in one direction (for example, the vertical or horizontal direction in the figure) or in two directions (for example, the vertical and horizontal directions in the figure) within the plane of the first resistive layer RR.

[0044] The resistance value (Ω / sq) of the first resistive layer RR is, specifically, for example, 20, 30, 40, 50, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, and may also be within the range of any two of the values ​​exemplified here. For example, the resistance value (Ω / sq) of the first resistive layer RR is, for example, 20 or more and 200 or less.

[0045] Furthermore, the thickness (μm) of the first resistive layer RR is specifically, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, and may also be within the range of any two of the values ​​exemplified here.

[0046] When each of the radio wave absorbing sheets 100A to 100F is viewed from a direction parallel to the thickness direction of each sheet, the entire formation area of ​​the resistive layer RR may be inside the outer edge of the second example of the resistive layer RR. In other words, when each of the radio wave absorbing sheets 100A to 100F is viewed from a direction parallel to the thickness direction, the entire resistive layer RR may overlap with a part of the second example of the resistive layer RR.

[0047] 3-2-2. Second resistive layer RR The second resistive layer RR does not necessarily have a function to select the frequency of radio waves to pass through. In the embodiment, the second resistive layer RR may be a so-called solid layer. The second resistive layer RR may be composed of a sheet-like structure in which the entire region inside the outer edge of the second resistive layer RR is filled with the constituent material of the second resistive layer RR.

[0048] The resistance value (Ω / sq) of the second resistive layer RR is, specifically, for example, 20, 30, 40, 50, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, and may also be within the range of any two of the values ​​exemplified here. For example, the resistance value (Ω / sq) of the second resistive layer RR is, for example, 20 or more and 200 or less.

[0049] Furthermore, the thickness (μm) of the second resistive layer RR is specifically, for example, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, and may also be within the range of any two of the values ​​exemplified here.

[0050] 3-2-3. Constituent materials of each resistive layer The constituent materials of the first and second resistive layers RR can be, for example, conductive organic polymer films, sputtered films, vapor-deposited films, etc. Furthermore, since the resistance value of the above-mentioned conductive organic polymer films, sputtered films, and vapor-deposited films can be controlled by the film thickness and formation density, a resistive layer with a desired resistance value can be easily formed. The constituent materials of the first and second resistive layers RR may be the same or different.

[0051] As the conductive organic polymers used as the first and second resistive layers RR, conjugated conductive organic polymers are used, and it is preferable to use polythiophene or its derivatives, or polypyrrole or its derivatives.

[0052] Furthermore, the first and second resistive layers RR can be organic polymers whose main chains are composed of π-conjugated polymers, and can include polyacetylene-based conductive polymers, polyphenylene-based conductive polymers, polyphenylene-vinylene-based conductive polymers, polyaniline-based conductive polymers, polyacene-based conductive polymers, polythiophene-vinylene-based conductive polymers, and copolymers thereof.

[0053] Polyanions can be used as counteranions for the conductive organic polymers used in the first and second resistive layers RR. While the polyanions are not particularly limited, those containing anionic groups that can induce chemical oxidation doping in the conjugated conductive organic polymer can be used. Examples of such anionic groups include those represented by the general formulas -O-SO3X, -O-PO(OX)2, -COOX, and -SO3X (where X is a hydrogen atom or alkali metal atom). Among these, the groups represented by -SO3X and -O-SO3X can be used because they exhibit excellent doping effects on the conjugated conductive organic polymer.

[0054] The above conductive organic polymers may be used individually or in combination of two or more. Among the materials exemplified above, polymers consisting of one or two selected from polypyrrole, poly(3-methoxythiophene), poly(3,4-ethylenedioxythiophene), poly(2-aniline sulfonic acid), and poly(3-aniline sulfonic acid) are preferred because they offer higher transparency and conductivity.

[0055] In particular, as a combination of a conjugated conductive organic polymer and a polyanion, it is preferable to use poly(3,4-ethylenedioxythiophene: PEDOT) and polystyrene sulfonic acid (PSS).

[0056] Furthermore, in the first and second resistive layers RR according to this embodiment, dopants can be used in combination to control the electrical conductivity of the conductive organic polymer and obtain a predetermined resistance value. As dopants, halogens such as iodine and chlorine, Lewis acids such as BF3 and PF5, protonic acids such as nitric acid and sulfuric acid, transition metals, alkali metals, amino acids, nucleic acids, surfactants, dyes, chloranil, tetracyanoethylene, TCNQ, etc. can be used.

[0057] The content of conductive organic polymer in the first and second resistive layers RR is preferably 10% by mass or more and 35% by mass or less, relative to the total mass of solids contained in the resistive layer composition. If the content is less than 10% by mass, the conductivity of the resistive layer tends to decrease. As a result, when the surface electrical resistance value of the resistive layer is set within a predetermined range to achieve impedance matching, the film thickness of the resistive layer increases, which tends to make each radio wave absorbing sheet 100A to 100F thicker overall, or, if it is translucent, the optical properties tend to decrease. On the other hand, if the content exceeds 35% by mass, the coating suitability when coating the resistive layer decreases due to the structure of the conductive organic polymer, making it difficult to form a good resistive layer, and if it is translucent, the haze of the resistive layer increases, which also tends to decrease the optical properties.

[0058] Furthermore, the first and second resistive layers RR may be configured to include carbon materials such as carbon microcoils, carbon nanotubes, and graphene.

[0059] Carbon microcoils are a type of vapor-grown carbon fiber primarily obtained by catalytically activated pyrolysis of acetylene, and are materials with a 3D-helical / spiral structure on the order of microns in coil diameter. Preferably, the coil diameter is 1 μm to 10 μm, the carbon fiber diameter forming the coil is 0.1 μm to 1 μm, and the coil length is 1 mm to 10 mm.

[0060] Carbon nanotubes can be obtained by various methods, such as vapor phase growth methods including arc discharge, laser evaporation, and thermal decomposition. The carbon nanotubes used as the first and second resistive layers (RR) may be single-layer or multi-layer.

[0061] Graphene can be obtained by methods such as peel transfer, SiC pyrolysis, chemical vapor deposition, or carbon nanotube cutting. For the graphene used as the first and second resistive layers RR, flaky powdered graphene can be used, as it allows for easy acquisition of the desired aspect ratio and provides orientation in the radio wave absorbing sheets 100A to 100F. A water-soluble polyester resin can be used as the resin for dispersing the carbon material.

[0062] The first and second resistive layers RR can be formed by applying a coating composition as a resistive layer-forming paint onto a resin substrate and drying it. Methods for applying the resistive layer-forming paint to the substrate include, for example, bar coating, reverse coating, gravure coating, microgravure coating, die coating, dipping, spin coating, slit coating, and spray coating. Drying after application should be carried out under conditions that allow the solvent components of the resistive layer-forming paint to evaporate, preferably at 100-150°C for 5-60 minutes. Alternatively, the first and second resistive layers RR may be formed by curing the coating film by irradiating it with UV light (ultraviolet light) or EB (electron beam) as needed. The substrate used to form the first and second resistive layers RR is not particularly limited, but a transparent substrate is preferred. Various materials such as PET resin, rubber, glass, and ceramics can be used for such a transparent substrate.

[0063] 3-3. Metal layer (reflection layer) Metal foils or metal plates can be used as the metal layers MM1 and MM2 that can be used as reflective layers. In order to give flexibility to the radio wave absorbing sheets 100A to 100F, metal foil is more preferable as the constituent material of the metal layers MM1 and MM2, and various metal foils such as silver foil, copper foil, aluminum foil, and gold foil can be used. When considering cost and the effect of oxidation in air, aluminum foil can be used as the reflective layer (metal layers MM1 and MM2). Metal foils such as aluminum foil that form the reflective layer (metal layers MM1 and MM2) can be easily produced by rolling a metal material. Furthermore, when forming the reflective layer (metal layers MM1 and MM2) with a vapor-deposited film in which metal is deposited on the surface of a non-metallic material, it is preferable to appropriately select a vapor deposition method that has been conventionally used to form various vapor-deposited films, taking into consideration the heat resistance temperature of the metal material to be deposited and the non-metallic material such as the resin that serves as the base material.

[0064] The thickness (μm) of each metal layer MM1 and MM2 can be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 500 (μm), and may be within the range of any two of the values ​​exemplified here. The thicknesses of each metal layer MM1 and MM2 may be different from each other.

[0065] 3-4.Adhesive layer Examples of adhesive layers (not shown) that can be used in the embodiment include, for example, known materials used as adhesive layers in adhesive tapes, acrylic adhesives, rubber adhesives, silicone adhesives, etc. Tackifiers and crosslinking agents can be used to adjust the adhesive strength and reduce adhesive residue. The adhesive strength can be, for example, 5N / 10mm to 12N / 10mm. The thickness (μm) of each adhesive layer (not shown) can be, specifically, for example, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, The ranges are 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, and 450, and any range between any two of the numbers exemplified here is also acceptable.

[0066] 3-5. Protective layer (protective film, etc.) There are no limitations on the material of the protective layer (not shown). The protective layer (not shown) is provided on the front and back surfaces of each component, respectively. The protective layer can be made of any material from the viewpoint of suitable protection and suitable peeling. Each component may be protected with, for example, any separator film or release film, and by peeling these off, the adhesive layer may be exposed, allowing the components to be bonded to each other via this adhesive layer.

[0067] As explained above, according to the embodiment, each layer of the radio wave absorbing sheet 100A to 100F, which has multiple layers, is packaged as a kit, allowing the user to arbitrarily combine the layer configuration of the radio wave absorbing sheet according to their purpose. This provides users with a variety of options and can also contribute to cost reduction. In other words, unlike conventional film-type radio wave absorbers that are sold as finished products, the components are packaged as kits, such as resistive layer components (resistive layer kit), metal layer components (metal layer kit), and dielectric layer components (dielectric layer kit). Users can select the combination of each component (resistive layer component R, metal layer components M1, M2, dielectric layer components D1 to D3) as needed (frequency band, specific incident angle, etc.).

[0068] 4. Variations, etc. At least one of the dielectric layer components D1 to D3 may consist of a pair of dielectric layers of different thicknesses. Alternatively, the dielectric layer components D1 to D3 are not limited to the uses illustrated in Figures 2A to 2F; for example, two dielectric layers of different thicknesses may be selected from each dielectric layer component D1 to D3 and used in combination.

[0069] Various embodiments are illustrated below. The embodiments shown below can be combined with each other. [Note 1] This is a radio wave absorbing sheet making kit, It comprises a resistive layer component, a metal layer component, and a dielectric layer component. The resistive layer component, the metal layer component, and the dielectric layer component are separated from each other. The resistive layer component has a resistive layer, the metal layer component has a metal layer, and the dielectric layer component has a pair of dielectric layers separated from each other. A radio wave absorbing sheet fabrication kit comprising the resistive layer component, the metal layer component, and the dielectric layer component, configured to be stacked in close contact with each other.

[0070] [Note 2] The radio wave absorbing sheet fabrication kit described in Appendix 1, The resistive layer component further comprises a pair of resistive layer component dielectric layers, The aforementioned resistive layer is disposed between the pair of resistive layer component dielectric layers in this radio wave absorbing sheet fabrication kit.

[0071] [Note 3] The radio wave absorbing sheet fabrication kit described in Appendix 2, A radio wave absorbing sheet fabrication kit that satisfies 0.9 × s ≤ p1 ≤ 1.1 × s, where p1 is the dielectric constant of the dielectric layer of each resistive layer component and s is the dielectric constant of the dielectric layer of the dielectric layer component.

[0072] [Note 4] A radio wave absorbing sheet configuration kit as described in any one of the appendices 1 to 3, The aforementioned metal layer component further comprises a pair of metal layer component dielectric layers, The aforementioned metal layer is placed between the pair of metal layer component dielectric layers in a radio wave absorbing sheet fabrication kit.

[0073] [Note 5] The radio wave absorbing sheet fabrication kit described in Appendix 4, A radio wave absorbing sheet fabrication kit that satisfies 0.9 × s ≤ p2 ≤ 1.1 × s, where p2 is the dielectric constant of the dielectric layer of each metal layer component and s is the dielectric constant of the dielectric layer of the dielectric layer component.

[0074] [Note 6] A radio wave absorbing sheet fabrication kit as described in any one of the appendices 1 to 5, A radio wave absorbing sheet fabrication kit, wherein at least one of the resistive layer component and the dielectric layer component further has an adhesive layer for bonding them together.

[0075] [Note 7] A radio wave absorbing sheet fabrication kit as described in any one of the appendices 1 to 6, A radio wave absorbing sheet fabrication kit, wherein at least one of the metal layer component and the dielectric layer component further has an adhesive layer for bonding them together.

[0076] [Note 8] A radio wave absorbing sheet made using the radio wave absorbing sheet manufacturing kit described in any one of the appendices 1 to 7, A radio wave absorbing sheet comprising one dielectric layer of the dielectric layer component, the resistive layer component, the other dielectric layer of the dielectric layer component, and the metal layer component, wherein these layers are stacked in this order from the radio wave incident side.

[0077] While embodiments have been described above, these are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications are permitted. The embodiments and their variations are included within the scope and essence of the invention, as well as within the scope of the invention and its equivalents as described in the claims. [Explanation of Symbols]

[0078] 100: Radio wave absorbing sheet making kit 100A~100F: Radio wave absorbing sheet R: Resistance layer parts RR: resistance layer DR1: Dielectric layer (dielectric layer of resistive layer component) M1, M2: Metal layer parts MM1, MM2: Metal layer DM1, DM2: Dielectric layer (metal layer component dielectric layer) D1, D2, D3: Dielectric layer components D1f, D1r, D2f, D2r, D3f, D3r: Dielectric layer 1RS: Periodic structure 1Ra: Resistive element section

Claims

1. This is a radio wave absorbing sheet making kit, It comprises a resistive layer component, a metal layer component, and a dielectric layer component. The resistive layer component, the metal layer component, and the dielectric layer component are separated from each other. The resistive layer component has a resistive layer, the metal layer component has a metal layer, and the dielectric layer component has a pair of dielectric layers separated from each other. A radio wave absorbing sheet fabrication kit comprising the resistive layer component, the metal layer component, and the dielectric layer component, configured to be stacked in close contact with each other.

2. A radio wave absorbing sheet manufacturing kit according to claim 1, The resistive layer component further comprises a pair of resistive layer component dielectric layers, The aforementioned resistive layer is disposed between the pair of resistive layer component dielectric layers in this radio wave absorbing sheet fabrication kit.

3. A radio wave absorbing sheet manufacturing kit according to claim 2, A radio wave absorbing sheet fabrication kit that satisfies 0.9 × s ≤ p1 ≤ 1.1 × s, where p1 is the dielectric constant of the dielectric layer of each resistive layer component and s is the dielectric constant of the dielectric layer of the dielectric layer component.

4. A radio wave absorbing sheet configuration kit according to claim 1, The aforementioned metal layer component further comprises a pair of metal layer component dielectric layers, The aforementioned metal layer is placed between the pair of metal layer component dielectric layers in a radio wave absorbing sheet fabrication kit.

5. A radio wave absorbing sheet manufacturing kit according to claim 4, A radio wave absorbing sheet fabrication kit that satisfies 0.9 × s ≤ p² ≤ 1.1 × s, where p² is the dielectric constant of the dielectric layer of each metal layer component and s is the dielectric constant of the dielectric layer of the dielectric layer component.

6. A radio wave absorbing sheet fabrication kit according to any one of claims 1 to 5, A radio wave absorbing sheet fabrication kit, wherein at least one of the resistive layer component and the dielectric layer component further has an adhesive layer for bonding them together.

7. A radio wave absorbing sheet fabrication kit according to any one of claims 1 to 5, A radio wave absorbing sheet fabrication kit, wherein at least one of the metal layer component and the dielectric layer component further has an adhesive layer for bonding them together.

8. A radio wave absorbing sheet made using the radio wave absorbing sheet manufacturing kit described in any one of claims 1 to 5, A radio wave absorbing sheet comprising one dielectric layer of the dielectric layer component, the resistive layer component, the other dielectric layer of the dielectric layer component, and the metal layer component, wherein these layers are stacked in this order from the radio wave incident side.

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