Electromagnetic wave absorbing member

Abstract

An electromagnetic wave absorption member (1) has a resistance layer (10), a spacer layer (20), and a reflection layer (30). The resistance layer (10), the spacer layer (20), and the reflection layer (30) are laminated in this order. The resistance layer (10) has a conductor pattern (11). The conductor pattern (11) is embedded in the spacer layer (20) in a surface (20a) that is on the reverse side from a surface (20b) facing the reflection layer (30).

Description

Electromagnetic wave absorbing materials

[0001] This application claims priority from Japanese Patent Application No. 2024-025870, filed on February 22, 2024, the contents of which are incorporated herein by reference.

[0002] A sheet-like electromagnetic wave absorbing member that selectively absorbs electromagnetic waves of a predetermined frequency is known. The electromagnetic wave absorbing member, for example, includes a first frequency selective shielding layer and a second frequency selective shielding layer. In such an electromagnetic wave absorbing member, each layer absorbs electromagnetic waves of a predetermined frequency by means of fine line patterns of FSS (Frequency Selective Surface) elements formed in the first frequency selective shielding layer and the second frequency selective shielding layer, and as a whole, the electromagnetic wave absorbing member selectively blocks electromagnetic waves of two different frequencies.

[0003] Depending on the application, an electromagnetic wave absorbing material is required to adhere closely to a curved surface when attached to the curved surface, and therefore the electromagnetic wave absorbing material is required to have sufficient electromagnetic wave absorption properties and excellent bending rigidity even when in close contact with the curved surface.

[0004] Patent Document 1 describes an electromagnetic wave shielding sheet that combines transparency that does not impair the visibility of a display screen and a frame portion of a metal layer with an exposed surface to which a ground can be connected. Specifically, the electromagnetic wave shielding sheet described includes a transparent substrate and a mesh-like metal layer provided on one surface of the transparent substrate via a transparent adhesive layer, the metal layer having a mesh portion with a large number of openings and line portions surrounding the openings, and a frame portion provided on the periphery of the mesh portion, the metal being exposed on the surface of the frame portion opposite the adhesive layer, and a transparent ionizing radiation-cured resin layer being embedded in the openings.

[0005] Patent Document 2 describes an in-vehicle antenna that allows easy layout of multiple antennas without compromising the design of the vehicle. Specifically, the in-vehicle dielectric antenna includes a vehicle component that is a dielectric resin component having a plate-shaped portion and that constitutes the outer shell of the vehicle, an antenna pattern formed on the outer surface of the plate-shaped portion of the vehicle component, a ground conductor layer formed on the inner surface of the plate-shaped portion of the vehicle component behind the antenna pattern, a transmitting / receiving unit provided on the back of the vehicle component for feeding power to the antenna pattern and / or acquiring signals from the antenna pattern, and a coating layer formed by painting on the outer surface of the vehicle component so as to cover the antenna pattern.

[0006] International Publication No. 2005 / 069713 Patent No. 6604359

[0007] However, the electromagnetic wave shielding sheet described in Patent Document 1 and the dielectric antenna described in Patent Document 2 have the problem that they do not have sufficient electromagnetic wave absorption properties and bending rigidity.

[0008] The present invention has been made in view of the above circumstances, and has an object to provide an electromagnetic wave absorbing member that is excellent in electromagnetic wave absorbing properties and flexural rigidity.

[0009] The present invention provides the following electromagnetic wave absorbing member: [1] An electromagnetic wave absorbing member having a resistive layer, a spacer layer, and a reflective layer, the resistive layer, the spacer layer, and the reflective layer being laminated in this order, the resistive layer having a conductor pattern, the conductor pattern being embedded in the spacer layer on the surface opposite to the surface facing the reflective layer. [2] The electromagnetic wave absorbing member according to [1], wherein the spacer layer has a relative dielectric constant of 5 or more.

[0010] According to the present invention, it is possible to provide an electromagnetic wave absorbing member that is excellent in electromagnetic wave absorbing properties and flexural rigidity.

[0011] Fig. 1 is a cross-sectional view of a surface along the thickness of an electromagnetic wave absorbing member according to an embodiment of the present invention; Fig. 2 is a top view showing an example of a resistance layer constituting the electromagnetic wave absorbing member according to an embodiment of the present invention; Fig. 3 is a cross-sectional view of a surface along the thickness of an electromagnetic wave absorbing member according to an embodiment of the present invention; Fig. 4 is a schematic view showing a method for measuring the bending rigidity of the electromagnetic wave absorbing member according to an embodiment of the present invention;

[0012] An embodiment of the electromagnetic wave absorbing member of the present invention will be described. Note that this embodiment is specifically described to provide a better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

[0013] In this specification, the term "conductor pattern" refers to an aggregate of geometrically shaped units, and refers to an object that selectively absorbs electromagnetic waves of a certain frequency. A "conductor pattern" can also be said to have the same function as an antenna. In this specification, "electromagnetic waves in the millimeter wave region" refers to electromagnetic waves with a wavelength of 1 mm to 10 mm. "Electromagnetic waves in the millimeter wave region" can also be said to be electromagnetic waves with a frequency of 30 GHz to 300 GHz. In this specification, the symbol "to" indicating a numerical range means that the numerical values ​​before and after it are included as the lower and upper limits.

[0014] [Electromagnetic Wave Absorbing Member] (First Embodiment) Fig. 1 is a cross-sectional view of a plane along the thickness direction of an electromagnetic wave absorbing member according to one embodiment of the present invention. As shown in Fig. 1, the electromagnetic wave absorbing member 1 of this embodiment has a resistance layer 10, a spacer layer 20, and a reflective layer 30. The resistance layer 10, the spacer layer 20, and the reflective layer 30 are laminated in this order.

[0015] The resistive layer 10 has a conductor pattern 11. The conductor pattern 11 is embedded in a surface (one surface (front surface)) 20a of the spacer layer 20 opposite a surface (the other surface (rear surface)) 20b facing the reflective layer 30. The outermost surface (top surface) 10a of the resistive layer 10 is disposed on the same plane as the one surface 20a of the spacer layer 20. The spacer layer 20 is disposed between the resistive layer 10 and the reflective layer 30. That is, the resistive layer 10 and the reflective layer 30 are stacked with the spacer layer 20 interposed therebetween.

[0016] The resistive layer 10 is a single layer. When the resistive layer 10 is a single layer, the resistive layer 10 is made of the same material as the conductive pattern 11 described later.

[0017] "Resistive Layer" The resistive layer 10 is made of a frequency selective surface (FSS). A frequency selective surface is a surface that can block or transmit only electromagnetic waves of a specific frequency by forming a continuous structure with a shape smaller than the wavelength using a conductive material or the like.

[0018] FIG. 2 is a top view showing an example of a resistive layer constituting an electromagnetic wave absorbing member according to one embodiment of the present invention. As shown in FIG. 2, the resistive layer 10 has a conductor pattern 11. The conductor pattern 11 is composed of, for example, a first conductor pattern 41, a second conductor pattern 42, and a third conductor pattern 43. The thicknesses of the first conductor pattern 41, the second conductor pattern 42, and the third conductor pattern 43 are not particularly limited. These thicknesses can be changed as desired depending on the desired characteristics. Furthermore, these three thicknesses may be the same or different from one another, but are preferably the same in terms of productivity. From the viewpoint of achieving both electromagnetic wave absorption and curved surface conformability, the thicknesses of the first conductor pattern 41, the second conductor pattern 42, and the third conductor pattern 43 are preferably 10 nm to 300 μm, more preferably 40 nm to 1 μm, and particularly preferably 80 nm to 400 nm.

[0019] (First Conductor Pattern) As shown in FIG. 2, the first conductor pattern 41 is composed of a plurality of first units u1. Each of the first units u1 is a geometric figure. In other words, the first conductor pattern 41 can be said to be a collection of first units u1, which are geometric figures. Each of the first units u1 functions as an antenna. The first conductor pattern 41 may be, for example, a thin-line pattern of an FSS element.

[0020] In the first conductor pattern 41, a plurality of first arrays R1 are formed, each of which has a plurality of first units u1 arranged along the direction indicated by the double-headed arrow P in FIG. 2 . It can also be said that the first conductor pattern 41 has a plurality of first arrays R1. The first conductor pattern 41 can be configured by forming a plurality of first arrays R1 at predetermined intervals in the spacer layer 20 along the direction indicated by the double-headed arrow P. The intervals between the plurality of first arrays R1 are not particularly limited. The intervals between the first arrays R1 may be regular or irregular.

[0021] As shown in Figure 2, the first unit u1 has a cross shape that is symmetrical in both the vertical and horizontal directions. Specifically, the first unit u1 has one cross portion S1 and four end portions T1. The cross portion S1 is composed of a straight line portion parallel to the x-axis direction and a straight line portion parallel to the y-axis direction in Figure 2. Linear end portions T1 contact both ends of the straight line portion parallel to the x-axis direction and both ends of the straight line portion parallel to the y-axis direction, respectively, so as to be perpendicular to each straight line portion.

[0022] By adjusting the length of the first unit u1 in the x-axis direction and the length of each of the four ends T1 in the x-axis direction, the electromagnetic wave absorption characteristics of the first unit u1 functioning as a single antenna can be adjusted. Similarly, the electromagnetic wave absorption characteristics can be adjusted in the y-axis direction.

[0023] However, the shape of the first unit is not limited to a cross shape. The shape of the first unit is not particularly limited as long as the frequency value at which the amount of electromagnetic waves absorbed by the first conductor pattern 41 reaches a maximum value is A [GHz]. For example, the shape of the figure that is the first unit may be a circle, an annular shape, a straight line, a square, a polygon, an H-shape, a Y-shape, a V-shape, etc.

[0024] In the resistive layer 10, the shapes of the multiple first units u1 are the same. However, the shapes of the multiple first units u1 do not have to be the same figures. In another example of the present invention, the shapes of the multiple first units may be the same or different as long as the absorption characteristics can be adjusted to the target frequency.

[0025] The first conductor pattern 41 improves the transmittance of electromagnetic waves having the following frequency A [GHz]. In the resistive layer 10 of this embodiment, the frequency value A is preferably 20 GHz to 110 GHz, more preferably 60 GHz to 100 GHz, even more preferably 65 GHz to 95 GHz, and particularly preferably 70 GHz to 90 GHz. When the frequency value A is within the above numerical range, the resulting electromagnetic wave absorbing member 1 can absorb electromagnetic waves in the millimeter wave region, making it easier to apply to automobile parts, road peripheral members, building exterior wall-related materials, windows, communication equipment, radio telescopes, etc.

[0026] The material of the first unit u1 is not particularly limited as long as its absorption characteristics can be adjusted to the desired frequency. Examples of materials for the first unit include thin metal wires, conductive thin films, and conductive paste fixations. Examples of metal materials include copper, aluminum, tungsten, iron, molybdenum, nickel, titanium, silver, gold, and alloys containing two or more of these metals (e.g., steels such as stainless steel and carbon steel, brass, phosphor bronze, zirconium-copper alloys, beryllium copper, iron-nickel, nichrome, nickel-titanium, Kanthal, Hastelloy, and rhenium-tungsten). Examples of materials for the conductive thin film include metal oxides such as tin oxide (ITO). Examples of materials for the conductive paste include metal particles, carbon nanoparticles, and carbon fibers.

[0027] The distance between the ends of the first unit u1 is not particularly limited as long as the absorption characteristics can be adjusted to the desired frequency. For example, the distances between the ends of the first unit u1 may all be the same or may be different from each other. However, it is preferable that the distances between the ends of the first unit u1 are the same, as this makes it easier to design a resistive layer that is less susceptible to the influence of the surrounding environment and improves the accuracy of the frequency band of the transmitted electromagnetic waves during manufacturing.

[0028] 2, the second conductor pattern 42 is made up of a plurality of second units u2. The second conductor pattern 42 is formed in the same manner as the first conductor pattern 41.

[0029] The second conductor pattern 42 selectively transmits electromagnetic waves having a frequency of B [GHz] that satisfies the following formula (1). The frequency value B [GHz] is the frequency value at which the amount of electromagnetic waves transmitted through the second conductor pattern 42 exhibits a maximum value. The frequency value B [GHz] satisfies the following formula (1): 1.037×A≦B≦1.30×A...formula (1)

[0030] As shown in the above formula (1), the second conductor pattern 42 transmits electromagnetic waves with frequencies of 1.037×A [GHz] to 1.30×A [GHz]. The second conductor pattern 42 preferably transmits electromagnetic waves with frequencies of 1.17×A [GHz] to 1.30×A [GHz]. Because the second conductor pattern 42 transmits electromagnetic waves with frequencies of 1.037×A [GHz] or higher, the peaks of the amount of electromagnetic wave transmitted by the second conductor pattern 42 and the peaks of the amount of electromagnetic wave transmitted by the first conductor pattern 41 sufficiently overlap in the frequency band higher than A [GHz]. As a result, the frequency band of electromagnetic waves that can be transmitted by the entire resistive layer 10 is expanded to a frequency band higher than A [GHz], compared to when the first conductor pattern 41 is provided alone. Because the second conductor pattern 42 transmits electromagnetic waves with frequencies of 1.30×A [GHz] or less, the frequency difference between the peak of the electromagnetic wave transmission amount through the second conductor pattern 42 and the peak of the electromagnetic wave transmission amount through the first conductor pattern 41 becomes small in the frequency band higher than A [GHz]. As a result, a single peak is formed at which the transmission amount of electromagnetic waves transmitted through the entire resistive layer 10 reaches a maximum value. As described above, because the second conductor pattern 42 transmits electromagnetic waves with frequencies of 1.037×A [GHz] to 1.30×A [GHz], the transmission amount of electromagnetic waves transmitted through the entire electromagnetic wave absorbing member 1 is expanded into the higher frequency band.

[0031] The material of the second units constituting the second conductor pattern 42 is not particularly limited as long as it can transmit electromagnetic waves of B [GHz] and can adjust the transmission characteristics to the desired frequency. The material of the second units is the same as that described for the material of the first units u1.

[0032] 2, the third conductor pattern 43 is composed of a plurality of third units u3. The third conductor pattern 43 is formed in the same manner as the first conductor pattern 41.

[0033] The third conductor pattern 43 selectively transmits electromagnetic waves having a frequency of C [GHz] that satisfies the following formula (2). The frequency value C [GHz] is the frequency value at which the amount of electromagnetic waves transmitted by the third conductor pattern 43 exhibits a maximum value. The frequency value C [GHz] satisfies the following formula (2): 0.60×A≦C≦0.963×A (2)

[0034] As shown in the above formula (2), the third conductor pattern 43 transmits electromagnetic waves with frequencies of 0.60×A [GHz] to 0.963×A [GHz]. The third conductor pattern 43 preferably transmits electromagnetic waves with frequencies of 0.60×A [GHz] to 0.83×A [GHz]. Because the third conductor pattern 43 transmits electromagnetic waves with frequencies of 0.60×A [GHz] or higher, the frequency difference between the peak of the amount of electromagnetic wave transmitted by the third conductor pattern 43 and the peak of the amount of electromagnetic wave transmitted by the first conductor pattern 41 is reduced in the frequency band lower than A [GHz]. As a result, a single peak is formed at which the amount of electromagnetic wave transmitted through the entire resistive layer 10 is maximized. Because the third conductor pattern 43 transmits electromagnetic waves with frequencies of 0.963×A [GHz] or less, the peak of the amount of electromagnetic waves transmitted by the third conductor pattern 43 and the peak of the amount of electromagnetic waves transmitted by the first conductor pattern 41 sufficiently overlap in the frequency band lower than A [GHz]. As a result, the frequency band of electromagnetic waves that can be transmitted through the entire resistive layer 10 is expanded to a frequency band lower than A [GHz] compared to a film having only the first conductor pattern 41. As described above, because the third conductor pattern 43 transmits electromagnetic waves with frequencies of 0.60×A [GHz] to 0.963×A [GHz], the amount of electromagnetic waves transmitted through the entire resistive layer 10 is expanded to a frequency band lower in frequency.

[0035] The material of the third unit u3 constituting the third conductor pattern 43 is not particularly limited as long as it can transmit electromagnetic waves of C [GHz] and the absorption characteristics can be adjusted to the desired frequency. The material of the third unit u3 is the same as that described for the material of the first unit u1.

[0036] In the resistive layer 10 shown in FIG. 2 , the first array R1, the second array R2, and the third array R3 are arranged adjacent to one another along the direction indicated by the double-headed arrow P. Because the first array R1, the second array R2, and the third array R3 are arranged adjacent to one another on the spacer layer 20, the frequency band of the electromagnetic waves selectively transmitted by the second conductor pattern 42 and the frequency band of the electromagnetic waves selectively transmitted by the third conductor pattern 43 overlap with each other, based on the frequency value A [GHz] of the peak position of the electromagnetic waves selectively transmitted by the first conductor pattern 41. As a result, the band of the electromagnetic waves transmitted by the entire resistive layer 10 is easily expanded toward both the high-frequency side and the low-frequency side, based on the frequency value A [GHz] of the peak position.

[0037] 2, the distance d1 between the first unit u1 and the second unit u2, the distance d2 between the second unit u2 and the third unit u3, and the distance d3 between the third unit u3 and the first unit u1 may be the same or different. The distance d1 may be, for example, 0.2 mm to 4 mm, 0.3 mm to 3 mm, or 0.5 mm to 2 mm. The distance d2 may be, for example, 0.2 mm to 4 mm, 0.3 mm to 3 mm, or 0.5 mm to 2 mm. The distance d3 may be, for example, 0.2 mm to 4 mm, 0.3 mm to 3 mm, or 0.5 mm to 2 mm. When the distances d1, d2, and d3 are each within the above-mentioned ranges, the band of electromagnetic waves transmitted through the entire resistive layer 10 is likely to be further expanded relative to the frequency value A [GHz] at the peak position.

[0038] In the resistive layer 10, the first unit u1, the second unit u2, and the third unit u3 have the same shape. However, the shapes of the first unit u1, the second unit u2, and the third unit u3 do not have to be the same. That is, in another example of the present invention, the shapes of the first unit u1, the second unit u2, and the third unit u3 may be the same or different from each other.

[0039] The Young's modulus of the resistance layer 10 is preferably 10 GPa or less, more preferably 7 GPa or less, and even more preferably 5 GPa or less. When the Young's modulus of the resistance layer 10 is equal to or less than the upper limit, the bending rigidity is reduced and the ability to follow a curved surface is improved. From the viewpoint of shape retention, the lower limit of the Young's modulus of the resistance layer 10 may be 0.5 GPa or more, 1 GPa or more, or 3 GPa or more.

[0040] The Young's modulus of the resistance layer 10 can be measured in accordance with JIS K7127:1999 "Plastics - Test methods for tensile properties - Part 3: Test conditions for films and sheets."

[0041] The resistive layer 10 can be fabricated, for example, by the following method. First, a spacer layer 20 is prepared. Next, a first conductor pattern 41, a second conductor pattern 42, and a third conductor pattern 43 are formed so as to be embedded on one surface 20a of the spacer layer 20. When forming each conductor pattern, the conductor pattern is formed so that the frequency value at which the amount of electromagnetic wave absorption by each conductor pattern is maximized is a predetermined value [GHz]. The order in which each conductor pattern is formed is not particularly limited. Each conductor pattern may be formed in the same process or in separate processes.

[0042] The method for forming each conductor pattern is not particularly limited as long as it can form a predetermined frequency. Examples of the method for forming each conductor pattern include the following: a printing method in which each conductor pattern is printed on one side 20a of the spacer layer 20 using a conductive paste; a development method in which each conductor pattern is developed on one side 20a of the spacer layer 20; a method in which a metal thin film is provided on one side 20a of the spacer layer 20 by sputtering, vacuum deposition, or lamination of a metal foil, and then the metal thin film is formed on one side 20a of the spacer layer 20 by photolithography; a method in which a metal wire is disposed on one side 20a of the spacer layer 20; a method in which each conductor pattern is formed on a substrate or a release member by the above-mentioned method, and the substrate or release member is laminated on one surface of the spacer layer that has been melt-molded and is before or during cooling, so that the conductor patterns are in contact with each other.

[0043] "Spacer Layer" The spacer layer 20 may have a single-layer structure or a multi-layer structure. The material of the spacer layer 20 can be selected appropriately depending on the application. For example, when used for the exterior of an automobile, it is preferable to select a material that has the ability to conform to curved surfaces and has excellent heat resistance. Examples of flexible materials include plastic films, nonwoven fabrics, and rubber sheets. Among these, plastic films are preferred from the viewpoint of ease of mixing with fillers.

[0044] The spacer layer 20 may contain a filler. The filler is not particularly limited as long as it has a high dielectric constant, and examples thereof include barium titanate, strontium titanate, calcium titanate, and titanium oxide.

[0045] The filler content in the spacer layer 20 is preferably 20% by volume or more and 60% by volume or less, more preferably 25% by volume or more and 50% by volume or less, and particularly preferably 30% by volume or more and 45% by volume or less. If the filler content exceeds the upper limit, the spacer layer 20 may become embrittled, making it difficult to manufacture the spacer layer 20. If the filler content is less than the lower limit, the thickness of the spacer layer 20 required to obtain the required electromagnetic wave absorption properties may become too large, and curved surface conformability may not be obtained.

[0046] The relative dielectric constant of the spacer layer 20 is preferably 5 or more, more preferably 7 or more, even more preferably 8 or more, and particularly preferably 9 or more. If the relative dielectric constant of the spacer layer 20 is less than the lower limit, the thickness of the spacer layer 20 will be large. By making the relative dielectric constant of the spacer layer 20 5 or more, the thickness of the spacer layer 20 can be made thin. This allows the electromagnetic wave absorbing member 1 to have better curved surface conformability. From the viewpoint of preventing the Young's modulus of the spacer layer 20 from becoming too high, the upper limit of the relative dielectric constant of the spacer layer 20 may be 30 or less, 25 or less, 20 or less, or 15 or less.

[0047] The relative dielectric constant of the spacer layer 20 can be measured by the method described in the examples below.

[0048] The melting point of the spacer layer 20, i.e., the melting point of the material constituting the spacer layer 20, is 150°C or higher, preferably 160°C or higher, and more preferably 170°C or higher. If the melting point of the spacer layer 20 is below the lower limit, the relative dielectric constant changes after a heat resistance test, resulting in a decrease in performance. The upper limit of the melting point of the spacer layer 20 may be 400°C or lower, 300°C or lower, 240°C or lower, or 190°C or lower, from the viewpoint of preventing the Young's modulus of the spacer layer 20 from becoming too high.

[0049] The melting point of the spacer layer 20 can be measured by the method described in the examples below.

[0050] The thickness of the spacer layer 20 is preferably 200 μm or more and 450 μm or less, more preferably 240 μm or more and 400 μm or less, and particularly preferably 280 μm or more and 340 μm or less. When the thickness of the spacer layer 20 is equal to or more than the lower limit, it is easy to obtain a spacer layer 20 having a high relative dielectric constant. When the thickness of the spacer layer 20 is equal to or less than the upper limit, bending rigidity is low and curved surface conformability is improved.

[0051] When considering the wavelength shortening effect of the spacer layer 20, the thickness of the spacer layer 20 is appropriately changed according to the wavelength of the electromagnetic wave to be absorbed and the relative dielectric constant of the spacer layer 20. When considering the wavelength shortening effect of the spacer layer 20, it is preferable that the thickness of the spacer layer 20 satisfy the following formula (1): (Thickness of the spacer layer 20) = (λ) × (¼) / (ε) １／２ ...Equation (1) In the above equation (1), λ is the wavelength of the incident electromagnetic wave, and ε is the relative dielectric constant of the spacer layer 20. The thickness of the spacer layer 20 may be adjusted appropriately to obtain absorption characteristics. For example, the thickness can be changed within a range of 0.1 to 3.0 times the thickness of the spacer layer 20 obtained by equation (1).

[0052] When the relationship between the thickness of the spacer layer 20 and the wavelength λ satisfies the above formula (1), the electromagnetic wave absorbing member 1 has a so-called λ / 4 structure. This further increases the maximum absorption amount of electromagnetic waves by the electromagnetic wave absorbing member 1. The thickness of the spacer layer 20 can be appropriately set within the range of 200 μm to 450 μm depending on the wavelength λ of the electromagnetic waves to be absorbed. The spacer layer 20 may be made of a material with a high dielectric constant. If the spacer layer 20 is a layer with a high dielectric constant, the thickness of the spacer layer 20 can be made relatively thin. When the dielectric constant of the spacer layer 20 is taken into consideration, it is preferable that the spacer layer 20 contains at least one material selected from the group consisting of barium titanate, titanium oxide, and strontium titanate.

[0053] The thickness of the spacer layer 20 can be measured by a constant pressure thickness measuring instrument manufactured by Teclock Corporation.

[0054] The Young's modulus of the spacer layer 20 is preferably 1000 MPa or less, more preferably 600 MPa or less, and even more preferably 400 MPa or less. When the Young's modulus of the spacer layer 20 is equal to or less than the upper limit, the curved surface conformability is improved. From the viewpoint of shape retention, the lower limit of the Young's modulus of the spacer layer 20 may be 50 MPa or more, 100 MPa or more, or 200 MPa or more.

[0055] The Young's modulus of the spacer layer 20 can be measured in accordance with JIS K7127:1999 "Plastics - Test methods for tensile properties - Part 3: Test conditions for films and sheets."

[0056] "Reflective Layer" The reflective layer 30 has two surfaces 30a and 30b. One surface 30a of the reflective layer 30 faces the other surface 20b of the spacer layer 20. In FIG. 1 , the reflective layer 30 is provided directly on the other surface 20b of the spacer layer 20. In this case, the reflective layer 30 is provided by directly providing a metal thin film or a metal oxide thin film on the other surface 20b of the spacer layer 20 by vapor deposition or the like. The reflective layer 30 is not particularly limited as long as it can reflect electromagnetic waves that arrive at the surface of the electromagnetic wave absorbing member 1 and pass through the electromagnetic wave absorbing member 1. A portion of the electromagnetic waves that arrive at the electromagnetic wave absorbing member 1 is reflected by or absorbed by the resistive layer 10. On the other hand, the electromagnetic waves that are not reflected or absorbed by the resistive layer 10 pass through the resistive layer 10. The electromagnetic waves that pass through the resistive layer 10 are reflected by the reflective layer 30 toward the resistive layer 10. For example, if the reflective layer 30 has conductivity, it can reflect electromagnetic waves that have passed through the resistance layer 10. Specifically, a resin film such as polyethylene terephthalate to which a metal foil such as aluminum foil or copper foil, or a metal plate such as a copper plate is attached may be used as the reflective layer 30. Instead of the metal foil or metal plate, a transparent conductive film such as ITO, or a mesh sheet formed of metal wires, may be used.

[0057] When the reflective layer 30 is made of a single layer as shown in FIG. 1, its thickness is not particularly limited, but may be, for example, 10 nm to 100 μm, 40 nm to 1 μm, or 80 nm to 400 nm.

[0058] On the other hand, when the reflective layer 30 is made of a resin film on which a metal foil or the like is formed, its thickness is preferably 1 μm to 300 μm, more preferably 10 μm to 200 μm, and even more preferably 30 μm to 150 μm. This range makes it easy to achieve both ease of handling and flexibility of the reflective layer. Furthermore, in this case, the Young's modulus of the reflective layer 30 is preferably 6 GPa or less, more preferably 5.5 GPa or less, and even more preferably 5 GPa or less. When the Young's modulus of the reflective layer 30 is equal to or less than the upper limit, the curved surface conformability is improved. The lower limit of the Young's modulus of the reflective layer 30 may be 0.5 GPa or more, 1 GPa or more, or 3 GPa or more.

[0059] The Young's modulus of the reflective layer 30 can be measured in accordance with JIS K7127:1999 "Plastics - Test methods for tensile properties - Part 3: Test conditions for films and sheets."

[0060] When the spacer layer 20 is formed on a conductive material such as a metal, the conductive material such as a metal serves as the reflective layer 30, and therefore the reflective layer 30 can be omitted.

[0061] For the purpose of applying the electromagnetic wave absorbing member 1 to the surfaces of various articles, an adhesive layer may be provided on the other surface 30b of the reflective layer 30. When an adhesive layer is provided on the other surface 30b of the reflective layer 30, a release film may be provided on the surface of the adhesive layer opposite to the side in contact with surface 30b. The release film is removed when the electromagnetic wave absorbing member 1 is used. Covering the adhesive surface with the release film improves handling during distribution.

[0062] Examples of adhesives constituting the adhesive layer include heat-sealing adhesives that bond by heat; adhesives that develop adhesiveness by wetting; and pressure-sensitive adhesives (adhesives) that bond by pressure. Among these, pressure-sensitive adhesives (pressure-sensitive adhesives) are preferred from the viewpoint of simplicity. Specific examples of adhesives include acrylic adhesives, urethane adhesives, rubber adhesives, polyester adhesives, silicone adhesives, polyvinyl ether adhesives, and the like. Among these, at least one selected from the group consisting of acrylic adhesives, urethane adhesives, and rubber adhesives is preferred, with acrylic adhesives being more preferred.

[0063] The electromagnetic wave absorbing member 1 of this embodiment may also include a protective layer formed on the outermost surface (upper surface) 10a of the resistance layer 10 and on one surface 20a of the spacer layer 20. The protective layer is not particularly limited as long as it can protect the resistance layer 10 and the spacer layer 20.

[0064] The electromagnetic wave absorbing member 1 of this embodiment has a bending rigidity of 240 N·mm ２ Preferably, it is 100 N mm or less. ２ More preferably, it is 60 N mm or less. ２ More preferably, it is 30 N mm or less. ２ When the bending rigidity of the electromagnetic wave absorbing member 1 is equal to or less than the upper limit, the ability to conform to a curved surface is improved. From the viewpoint of shape retention, the lower limit of the bending rigidity of the electromagnetic wave absorbing member 1 is 1 N mm ２ or more, and ２ It may be 8 N mm or more. ２ It may be more than that.

[0065] The bending rigidity of the electromagnetic wave absorbing member 1 can be measured by the method described in the examples below.

[0066] Furthermore, the total thickness of the electromagnetic wave absorbing member 1 of this embodiment (the total thickness from the outermost surface (upper surface) 10a of the resistance layer 10 and one surface 20a of the spacer layer 20 to the other surface 30b of the reflective layer 30) is preferably 100 μm to 700 μm, more preferably 200 μm to 600 μm, even more preferably 250 μm to 500 μm, and particularly preferably 280 μm to 340 μm, from the viewpoint of achieving both curved surface conformability and electromagnetic wave absorption.

[0067] According to the electromagnetic wave absorbing member 1 of this embodiment, the conductor pattern 11 of the resistance layer 10 is embedded on one surface 20a of the spacer layer 20, resulting in excellent electromagnetic wave absorbency and bending rigidity. Furthermore, because the conductor pattern 11 of the resistance layer 10 is embedded on one surface 20a of the spacer layer 20, the member has excellent durability against chemicals. Furthermore, because the conductor pattern 11 of the resistance layer 10 is embedded on one surface 20a of the spacer layer 20, the conductor pattern 11 is less likely to be damaged by physical impact. Furthermore, because the electromagnetic wave absorbing member 1 of this embodiment does not use an adhesive to embed the conductor pattern 11 of the resistance layer 10 on one surface 20a of the spacer layer 20, corrosion of the conductor pattern 11 due to the adhesive does not occur.

[0068] According to the electromagnetic wave absorbing member 1 of this embodiment, if the relative dielectric constant of the spacer layer 20 is 5 or more, the ability to conform to a curved surface and the maintenance of electromagnetic wave absorbing properties after a heat resistance test are excellent.

[0069] Second Embodiment Fig. 3 is a cross-sectional view of an electromagnetic wave absorbing member according to one embodiment of the present invention, taken along the thickness direction. As shown in Fig. 3, the electromagnetic wave absorbing member 100 of this embodiment includes a resistive layer 110, a spacer layer 120, a reflective layer 130, and a support substrate 140. The resistive layer 110, the spacer layer 120, the reflective layer 130, and the support substrate 140 are laminated in this order. Pressure-sensitive adhesive layers 150 are provided on one surface 130a and the other surface 130b of the reflective layer 130. The reflective layer 130 is laminated on the spacer layer 120 via the pressure-sensitive adhesive layer 150. Hereinafter, the pressure-sensitive adhesive layer 150 provided on one surface 130a of the reflective layer 130 may be referred to as a first pressure-sensitive adhesive layer 151, and the pressure-sensitive adhesive layer 150 provided on the other surface 130b of the reflective layer 130 may be referred to as a second pressure-sensitive adhesive layer 152.

[0070] The conductor pattern 112 of the resistive layer 110 is embedded in a surface (one surface (front surface)) 120a of the spacer layer 120 opposite to a surface (the other surface (rear surface)) 120b facing the reflective layer 130. The outermost surface (top surface) 112a of the conductor pattern 112 is disposed on the same plane as the one surface 120a of the spacer layer 120. The spacer layer 120 is disposed between the resistive layer 110 and the reflective layer 130. That is, the resistive layer 110 and the reflective layer 130 are stacked with the spacer layer 120 interposed therebetween.

[0071] "Resistance Layer" The resistance layer 110 includes a substrate 111 and a conductor pattern 112 formed on one surface 111a of the substrate 111. The conductor pattern 112 has the same configuration as the conductor pattern 11 described above.

[0072] The substrate 111 is not particularly limited as long as it has a flat plate shape and can have one surface 111a on which the conductor pattern 112 can be formed. The substrate 111 may have a single-layer structure or a multi-layer structure.

[0073] The thickness of the substrate 111 may be, for example, 5 μm to 500 μm, 15 μm to 200 μm, or 25 μm to 100 μm.

[0074] The material of the substrate 111 can be selected appropriately depending on the application of the electromagnetic wave absorbing member 100. For example, the substrate 111 may be made of a transparent material in order to provide transparency to the electromagnetic wave absorbing member 100. Alternatively, the substrate 111 may be made of a flexible material in order to provide conformability to the curved surface of the electromagnetic wave absorbing member 100. The surface of the substrate 111 may be smoothed in order to improve the transparency and three-dimensional formability of the electromagnetic wave absorbing member 100.

[0075] For example, the substrate 111 can be made of a resin. The resin may be a thermoplastic resin or a thermosetting resin. However, when the three-dimensional formability of the electromagnetic wave absorbing member 100 is taken into consideration, the substrate 111 preferably contains a thermoplastic resin. Examples of thermoplastic resins include polyolefin resins, polyester resins, polyester-polyether resins, polyacrylic resins, polystyrene resins, polyimide resins, polyimideamide resins, polyamide resins, polyurethane resins, polycarbonate resins, polyarylate resins, melamine resins, epoxy resins, urethane resins, silicone resins, and fluororesins. Specific examples of polyolefin resins include polypropylene and polyethylene. Specific examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

[0076] The base material 111 may contain optional components within the scope of not impairing the effects of the present invention. Examples of the optional components include inorganic fillers, colorants, curing agents, antioxidants, light stabilizers, flame retardants, conductive agents, antistatic agents, and plasticizers.

[0077] In consideration of further improving the electromagnetic wave absorption performance of the electromagnetic wave absorbing member 100, the thickness, dielectric constant, electrical conductivity, and magnetic permeability of the substrate 111 can be set as appropriate.

[0078] "Spacer Layer" The spacer layer 120 has the same structure as the spacer layer 20 described above.

[0079] "Reflective Layer" The reflective layer 130 has the same structure as the reflective layer 30 described above.

[0080] "Supporting Substrate" The supporting substrate 140 is laminated on the other surface 130b of the reflective layer 130 via the second adhesive layer 152. One surface 140a of the supporting substrate 140 faces the other surface 130b of the reflective layer 130.

[0081] "Adhesive Layer (First Adhesive Layer, Second Adhesive Layer)" Examples of adhesives constituting the first adhesive layer 151 and the second adhesive layer 152 include heat-seal type adhesives that bond by heat; adhesives that develop stickiness by wetting; and pressure-sensitive adhesives (adhesives) that bond by pressure. Among these, pressure-sensitive adhesives (adhesives) are preferred from the viewpoint of simplicity. Specific examples of adhesives include acrylic adhesives, urethane adhesives, rubber adhesives, polyester adhesives, silicone adhesives, polyvinyl ether adhesives, and the like. Among these, at least one selected from the group consisting of acrylic adhesives, urethane adhesives, and rubber adhesives is preferred, with acrylic adhesives being more preferred.

[0082] The thickness of the first adhesive layer 151 and the second adhesive layer 152 is not particularly limited, but may be, for example, 1 μm to 1000 μm, 5 μm to 500 μm, or 10 μm to 40 μm.

[0083] The electromagnetic wave absorbing member 100 of this embodiment has a bending rigidity of 240 N·mm ２ Preferably, it is 120 N mm or less. ２ More preferably, it is 60 N mm or less. ２ When the bending rigidity of the electromagnetic wave absorbing member 100 is equal to or less than the upper limit, the ability to conform to a curved surface is improved. From the viewpoint of shape retention, the lower limit of the bending rigidity of the electromagnetic wave absorbing member 100 is 5 N mm ２ It may be 10 N mm or more. ２ It may be 20 N mm or more. ２ It may be more than that.

[0084] The bending rigidity of the electromagnetic wave absorbing member 100 can be measured by the method described in the examples below.

[0085] Furthermore, the total thickness of the electromagnetic wave absorbing member 100 of this embodiment (the total thickness from the outermost surface of the resistive layer, i.e., one surface (surface) 110a of the resistive layer 110 to the surface (other surface) 140b on the installation surface side of the support substrate 140) is preferably 150 μm to 1000 μm, more preferably 200 μm to 800 μm, even more preferably 250 μm to 650 μm, and particularly preferably 350 μm to 430 μm, from the viewpoint of achieving both curved surface conformability and electromagnetic wave absorption properties.

[0086] According to the electromagnetic wave absorbing member 100 of this embodiment, the conductor pattern 112 of the resistance layer 110 is embedded on one surface 120a side of the spacer layer 120, and therefore has excellent electromagnetic wave absorbency and bending rigidity. Furthermore, the conductor pattern 112 of the resistance layer 110 is embedded on one surface 120a side of the spacer layer 120 and is further protected by the substrate 111, and therefore has excellent durability against chemicals. For the same reason, the conductor pattern 112 is less likely to be damaged by physical impact.

[0087] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0088] Example 1 "Preparation of Electromagnetic Wave Absorbing Member" A pattern of washable ink was printed on a substrate made of a 50 μm-thick PET film (product name: PET50A4160, manufactured by Toyobo Co., Ltd.), and a 100 nm-thick copper thin film was formed by vapor deposition. The ink was then washed with water, and the copper thin film on the washable ink was removed, resulting in a conductive pattern as shown in FIG. 2 , which yielded a resistive layer. Next, a polyester-polyether copolymer (product name: P-55B, manufactured by Toyobo Co., Ltd.) as a resin and barium titanate (product name: BT-UP2, manufactured by Nippon Chemical Industry Co., Ltd.) as a filler were kneaded at 200°C and 40 rpm for 5 minutes using a Labo Plastomill (model name: 4C150, manufactured by Toyo Seiki Seisakusho Co., Ltd.) to prepare a mixed material containing 40% by volume of barium titanate. The above mixed material was placed on the conductive pattern-formed surface of the resistive layer and pressed at 200°C for 3 minutes using a hydraulic heating press (model: SA-32, manufactured by Tester Sangyo Co., Ltd.) to obtain a laminate consisting of a resistive layer with a total thickness of 350 μm and a spacer layer (thickness: 300 μm). An acrylic copolymer with a weight-average molecular weight of 800,000 and consisting of 70% by weight of 2-ethylhexyl acrylate, 29% by weight of n-butyl acrylate, 0.5% by weight of acrylic acid, and 0.5% by weight of 2-hydroxyethyl acrylate was prepared as the adhesive layer material. To 100 parts by weight (solid content equivalent) of the acrylic copolymer, 1 part by weight (solid content equivalent) of an isocyanate-based crosslinking agent and 8 parts by weight of an ultraviolet absorber (trade name: Tinuvin 477, manufactured by BASF Japan Ltd.) were added, and the mixture was diluted with ethyl acetate to prepare an acrylic adhesive solution. Next, the above acrylic adhesive solution was applied to a release film, dried at 90 ° C for 1 minute, and then cured at room temperature for 1 week to obtain a 20 μm thick adhesive layer. Next, a 50 μm thick aluminum-deposited PET film (manufactured by Toray Advanced Film Co., Ltd., product name: Metalme TS; aluminum layer thickness 100 nm) was prepared as a reflective layer, and the aluminum-deposited side of the film was laminated so as to cover the adhesive layer, and the release film present on the adhesive layer was removed. Then, the exposed side of the adhesive layer was attached to the exposed side of the spacer layer in the laminate to obtain an electromagnetic wave absorbing member.

[0089] Example 2: A pattern of water-washable ink was printed on a substrate made of a 50 μm-thick PET film without an easy-adhesion layer, and a 100 nm-thick copper thin film was formed by vapor deposition. The ink was then washed with water, and the copper thin film on the water-washable ink was removed, resulting in a conductive pattern as shown in FIG. 2 , which yielded a resistive layer. Next, a polyester-polyether copolymer (product name: P-55B, manufactured by Toyobo Co., Ltd.) as a resin and barium titanate (product name: BT-UP2, manufactured by Nippon Chemical Industry Co., Ltd.) as a filler were kneaded at 200°C and 40 rpm for 5 minutes using a Labo Plastomill (model name: 4C150, manufactured by Toyo Seiki Seisakusho Co., Ltd.) to prepare a mixed material containing 40% by volume of barium titanate. The mixed material was placed on the conductive pattern-formed surface of the resistive layer and pressed for 3 minutes using a hydraulic heating press (model name: SA-32, manufactured by Tester Sangyo Co., Ltd.) with the lower pedestal set to 180°C and the upper pedestal set to 220°C, to obtain a laminate of a resistive layer and a spacer layer (thickness: 300 μm) with a total thickness of 350 μm. Next, copper was vapor-deposited to a thickness of 100 nm on the surface of the laminate opposite to the resistive layer using a sputtering device. Finally, the PET film serving as the base material of the resistive layer was peeled off to obtain an electromagnetic wave absorbing member.

[0090] Comparative Example: "Preparation of Electromagnetic Wave Absorbing Member" A resistive layer was obtained in the same manner as in Example 1. Next, a polyester-polyether copolymer (product name: P-55B, manufactured by Toyobo Co., Ltd.) as the resin and barium titanate (product name: BT-UP2, manufactured by Nippon Chemical Industry Co., Ltd.) as the filler were kneaded for 5 minutes at 200°C and 40 rpm using a Labo Plastomill (model name: 4C150, manufactured by Toyo Seiki Seisakusho Co., Ltd.) to prepare a mixed material containing 40% by volume of barium titanate. The mixed material was pressed for 3 minutes at 200°C using a hydraulic heating press (model name: SA-302, manufactured by Tester Sangyo Co., Ltd.) to obtain a spacer layer with a thickness of 300 μm. An acrylic copolymer with a weight-average molecular weight of 800,000 and consisting of 70% by weight of 2-ethylhexyl acrylate, 29% by weight of n-butyl acrylate, 0.5% by weight of acrylic acid, and 0.5% by weight of 2-hydroxyethyl acrylate was prepared as the adhesive layer material. To 100 parts by mass (solid content equivalent) of the acrylic copolymer, 1 part by mass (solid content equivalent) of an isocyanate-based crosslinking agent and 8 parts by mass of an ultraviolet absorber (product name: Tinuvin 477, manufactured by BASF Japan Ltd.) were added, and the mixture was diluted with ethyl acetate to prepare an acrylic adhesive solution. The acrylic adhesive solution was then coated on a release film, dried at 90°C for 1 minute, and then aged at room temperature for 1 week to obtain an adhesive layer with a thickness of 20 μm. Next, the adhesive layer was laminated on one side of the spacer layer, the release film of the adhesive layer was peeled off, and the resistive layer was laminated on the exposed surface of the adhesive layer so that the conductive pattern side was in contact with the exposed surface of the adhesive layer. Next, a 50 μm thick aluminum-vapor-deposited PET film (manufactured by Toray Advanced Film Co., Ltd., product name: Metalme TS; aluminum layer thickness: 100 nm) was prepared as a reflective layer. The aluminum-vapor-deposited surface of the film was covered with an adhesive layer, the release film was peeled off, and the resistive layer was attached to the exposed surface of the spacer layer. In this way, an electromagnetic wave absorbing member was obtained.

[0091] [Evaluation] The electromagnetic wave absorbing members of Examples 1 and 2 and the Comparative Example were evaluated as follows. The results are shown in Table 1.

[0092] "Evaluation of curved surface conformability" Measurement samples were prepared by attaching the pressure-sensitive adhesive layer prepared in Example 1 to the surface of the reflection layer side of the electromagnetic wave absorbing members obtained in the Examples and Comparative Examples. The release film was peeled off from the measurement samples, and the measurement samples were attached to curved surfaces of different diameters to evaluate the curved surface conformability of the electromagnetic wave absorbing members. The smallest curved surface diameter (mm) at which the electromagnetic wave absorbing members could be attached to the curved surfaces without appearance defects such as wrinkles or lifted edges was evaluated.

[0093] "Evaluation of Flexural Rigidity" The flexural rigidity of the electromagnetic wave absorbing member was calculated using Fig. 4 and the following formula (11). The position of the centroid of the electromagnetic wave absorbing member in Fig. 4 is taken as y ｃ The width of the electromagnetic wave absorbing member is W. Furthermore, the thicknesses of the resistive layer, the spacer layer, and the reflective layer are t １ , t ２ , t ３ The height to the center of each layer is y １ , y ２ , y ３ The areas of the resistive layer, the spacer layer, and the reflective layer (A １ , A ２ , A ３ ) and the total area A and y １ , y ２ , y ３ was calculated from the following formulas (11) to (17). １ = W × t １ (11) A ２ = W × t ２ (12) A ３ = W × t ３ (13) A=A １ +A ２ +A ３ (14) y １ = t １ / 2 (15) y ２ = t １ +t ２ / 2 (16) y ３ = t １ +t ２ +t ３ / 2 (17) Using the values ​​obtained from equations (11) to (17), the centroid y of the electromagnetic wave absorbing member ｃ was calculated using the following formula (18):ｃ = (A １ y １ +A ２ y ２ +A ３ y ３ ) / A (18) Here, the second moment of area I １ , I ２ , I ３ and I ｃ１ , I ｃ２ , I ｃ３ was calculated using the following formulas (20) to (25). １ = (W × t １ ３ ) / 12 (20) I ２ = (W × t ２ ３ ) / 12 (21) I ３ = (W × t ３ ３ ) / 12 (22) I ｃ１ =I １ +A １ × (y ｃ -y １ ) ２ (23) I ｃ２ =I ２ +A ２ × (y ｃ -y ２ ) ２ (24) I ｃ３ =I ３ +A ３ × (y ｃ -y ３ ) ２ (25) The second moment of area I of the electromagnetic wave absorbing member was calculated using the following formula (26), and the bending rigidity of the electromagnetic wave absorbing member was calculated using the following formula (27). I = I ｃ１ +I ｃ２ +I ｃ３ (26) Bending rigidity (N mm ２ ) = E (N / mm ２ ) x I (mm ４ ) (27)

[0094] "Evaluation of Return Loss" A heat resistance test of the electromagnetic wave absorbing member was carried out using a high-temperature, constant-temperature chamber (model: PHH-102) manufactured by Espec Corporation. The temperature of the high-temperature, constant-temperature chamber was set to 120°C, and the electromagnetic wave absorbing member was placed in the high-temperature, constant-temperature chamber for 240 hours. The return loss of the electromagnetic wave absorbing member after removal from the high-temperature, constant-temperature chamber was measured, and the change before and after the test was evaluated. The return loss was measured by the free space method.

[0095] "Measurement of Young's modulus" A tensile test was performed under the following conditions on the resistive layer obtained in Example 1, the spacer layer obtained in the comparative example, and the aluminum-deposited PET film serving as the reflective layer used in Example 1. From the strain and stress measurement results, the change in stress relative to the change in strain was graphed. Young's modulus was measured from the initial slope of the change in stress relative to the change in strain. The results are shown in Table 1. Apparatus: Shimadzu Corporation tensile tester AG-X plus 10 kN Test sample size: Measurement area length 50 mm x width 15 mm Tensile test speed: 200 mm / min

[0096]

[0097] The results shown in Table 1 show that the electromagnetic wave absorbing members of Examples 1 and 2 were excellent in electromagnetic wave absorption property and flexural rigidity after the thermal test. On the other hand, the electromagnetic wave absorbing member of Comparative Example was poor in maintaining electromagnetic wave absorption property after the thermal test.

[0098] The electromagnetic wave absorbing member of the present invention can be suitably used as an electromagnetic wave absorbing member for transportation equipment such as automobiles.

[0099] REFERENCE SIGNS LIST 1,100 Electromagnetic wave absorbing member 10,110 Resistive layer 11,112 Conductive pattern 20,120 Spacer layer 30,130 Reflective layer 41 First conductive pattern 42 Second conductive pattern 43 Third conductive pattern 111 Substrate 140 Support substrate 150 Pressure-sensitive adhesive layer

Claims

1. An electromagnetic wave absorbing member having a resistive layer, a spacer layer, and a reflective layer, the resistive layer, the spacer layer, and the reflective layer being laminated in this order, the resistive layer having a conductor pattern, and the conductor pattern being embedded in the spacer layer on the side opposite to the side facing the reflective layer.

2. The electromagnetic wave absorbing member according to claim 1, wherein the relative dielectric constant of said spacer layer is 5 or more.

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