Laminated sheet, signal transmitter / receiver, and mobile body

Abstract

An object of the present invention is to provide a laminate sheet that can be suitably used as an electromagnetic wave shielding material for reducing false detection and malfunction of communication devices. [Solution] A laminated sheet comprising a laminated composition part in which two or more types of layers with different particle amounts are regularly stacked in 5 to 1001 layers, and on at least one side, the return loss at the maximum peak of the return loss curve in the frequency band of 1 GHz to 1000 GHz is 5.0 dB to 100 dB, and in which, when the layer in the laminated composition part has the smallest particle amount as layer A and the layer with the largest particle amount as layer B, the layer thickness distribution of each layer of the laminated composition part is plotted with the horizontal axis as layer number and the vertical axis as layer thickness, and the slope Adif of the layer thickness distribution of layer A is larger than the slope Bdif of the layer thickness distribution of layer B, the section in which the slope Adif of the layer thickness distribution of layer A is larger than the slope Bdif of the layer thickness distribution of layer B continues over 10% to 100% of the number of layers.

Description

[Technical Field]

[0001] The present invention relates to a laminated sheet capable of reducing false detection and malfunction of communication devices, and to a signal transceiver and a mobile object using the same. [Background technology]

[0002] With advances in communication technology, electromagnetic waves have come to be used as a means of communication in recent years, and for example, meter waves in the band of several hundred MHz to several GHz are mainly used for mobile phones and wireless communications, etc. Also, centimeter waves in the band of several GHz to several tens of GHz are mainly used for mobile communications such as 4G and 5G and wireless LAN (Wi-Fi) communications, while millimeter waves in the band of several tens of GHz to several hundred GHz are mainly used for automobile collision prevention radar, etc.

[0003] As such, the frequency band of electromagnetic waves is selected based on factors such as the amount of information, the transmission distance, the device, and the application. However, because electromagnetic waves of similar frequency bands are used in various devices and applications, there are concerns about device malfunctions, communication disruptions, and information leaks. Effects on the human body, which is sensitive to electromagnetic waves, have also been noted. In response to these concerns and comments, there is a growing need for electromagnetic wave shielding materials that block the electromagnetic waves that lead to the above-mentioned problems. In particular, in recent years, the development of communication technologies that utilize electromagnetic waves in the GHz frequency band has accelerated in order to achieve high-speed, large-capacity communications, and electromagnetic wave shielding materials that can block electromagnetic waves in this frequency band are in demand.

[0004] Electromagnetic waves propagate through space as waves made up of two components: an electric field and a magnetic field. Electromagnetic shielding materials can reflect electromagnetic waves on their surface or inside, or absorb them internally, thereby losing or attenuating the energy they contain. Combining reflection and absorption can further improve shielding performance.

[0005] For example, conductive reflection technology that uses reflection on the surface of an electromagnetic wave shielding material can be made more effective by creating a difference in the electrical resistance value (impedance calculated based on the dielectric constant) between the air interface and the electromagnetic wave shielding material interface. Generally, high electromagnetic wave shielding properties can be achieved over a wide range of frequency bands by applying and laminating a material with very low resistance, such as metal (copper), to the surface of the substrate (Patent Document 1).

[0006] On the other hand, electromagnetic wave absorption technology for electromagnetic wave shielding materials involves incorporating conductive or magnetic materials into the material, converting the electromagnetic waves that enter the material into induced currents, thereby dissipating the energy of the electromagnetic waves. More specifically, absorption performance can be achieved by incorporating metal materials such as carbon materials or ferrite into dielectric polymers such as rubber (Patent Documents 2 to 4). Furthermore, by overlapping layers with different impedances, electromagnetic waves reflected from the front and back of the electromagnetic wave shielding material can be interfered with and canceled out, resulting in electromagnetic wave loss (Patent Document 5).

[0007] While the electromagnetic wave shielding properties due to absorption vary depending on the combination of a dielectric (insulating) substrate and the conductive material contained therein, the thickness of the substrate, and the formulation of the conductive material (type of material, combination, and content), the arrangement of the conductive material within the substrate is also an important factor affecting the electromagnetic wave shielding properties. For example, there is a finding known as the Maxwell-Wagner effect, which suggests that in order to improve the conductivity of an electromagnetic wave shielding material, the conductive materials can be arranged in a specific direction within the material so that they are stacked side by side, thereby increasing the electromagnetic wave absorption effect of the entire electromagnetic wave shielding material (Non-Patent Document 1). Examples of electromagnetic wave absorbing materials that utilize the Maxwell-Wagner effect include films in which low-dielectric and high-dielectric layers are alternately laminated (Patent Documents 6 and 7). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special Publication No. 2011-502285 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-158395 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-118073 [Patent Document 4] Japanese Patent Application Publication No. 2019-057730 [Patent Document 5] Japanese Patent Application Publication No. 2019-102665 [Patent Document 6] International Publication No. 2021 / 100566 [Patent Document 7] China Publication No. 106413367 [Non-patent literature]

[0009] [Non-Patent Document 1] ZMDang,Prog.Matter.Sci.,2012,57,660-723 Summary of the Invention [Problem to be solved by the invention]

[0010] However, the electromagnetic shielding material disclosed in Patent Document 1, which utilizes conductive reflection technology due to surface reflection, requires the shielding material to be installed at a position separating the electromagnetic wave source from the protected object in order to fully demonstrate its effectiveness. Therefore, it is unsuitable for applications such as protecting a radar from electromagnetic waves emitted by the radar. Furthermore, absorbers utilizing losses due to interference or cancellation, such as those disclosed in Patent Documents 2 to 5, generally have a strong angular dependence on the amount of absorption, making them unsuitable for applications where electromagnetic waves that cause malfunctions or other problems are transmitted from a wide angle. As shown in Patent Documents 6 and 7, attempts have been made to utilize the Maxwell-Wagner effect to increase the absorption of electromagnetic waves incident on electromagnetic shielding materials from oblique angles, but sufficient effects have not been achieved. In other words, these electromagnetic shielding materials have issues with reducing false detection and malfunctions in communication devices.

[0011] Therefore, an object of the present invention is to provide a laminate sheet that can be suitably used as an electromagnetic wave shielding material for reducing false detection and malfunction of communication devices. [Means for solving the problem]

[0012] In order to solve the above problems, the first laminate sheet of the present invention and the second laminate sheet of the present invention have the following configuration.

[0013] The first laminate sheet of the present invention includes a laminated structure in which two or more layers having different particle amounts are regularly stacked in 5 to 1001 layers, and on at least one side, the return loss at the maximum peak of a return loss curve in a frequency band of 1 GHz to 1000 GHz is 5.0 dB to 100 dB, and in a layer thickness distribution of each layer of the laminated structure, where the layer with the smallest particle amount is layer A and the layer with the largest particle amount is layer B, the horizontal axis is the layer number and the vertical axis is the layer thickness, the section in which the slope Adif of the layer thickness distribution of layer A is larger than the slope Bdif of the layer thickness distribution of layer B continues over 10% to 100% of the number of layers.

[0014] The second laminate sheet of the present invention includes a laminate component in which two or more types of layers having different particle amounts are regularly stacked in 5 to 1001 layers, and at least one side has a return loss of 5.0 dB to 100 dB at the maximum peak of a return loss curve in a frequency band of 1 GHz to 1000 GHz, and the layer with the greatest particle amount among the layers constituting the laminate component is called layer B. When the laminate component is divided into two equal units by a plane perpendicular to the thickness direction, the units with the larger and smaller thickness ratios of layer B are called laminate unit X and laminate unit Y, respectively, and the thickness ratios (%) of layer B in laminate unit X and laminate unit Y are called laminate unit X and laminate unit Y, respectively, the ratio tBX - tBY is 5.0% to 90%.

[0015] The first laminate sheet of the present invention and the second laminate sheet of the present invention can also be in the following forms, and a signal transceiver or a mobile object can also be obtained using these as described below. (1) A laminated sheet comprising a laminated structure in which two or more types of layers with different particle amounts are regularly stacked in 5 to 1001 layers, and on at least one side, a return loss at the maximum peak of a return loss curve in a frequency band of 1 GHz to 1000 GHz is 5.0 dB to 100 dB, and in a layer thickness distribution of each layer of the laminated structure, where the layer with the smallest particle amount is layer A and the layer with the largest particle amount is layer B, the horizontal axis is the layer number and the vertical axis is the layer thickness, the section in which the slope Adif of the layer thickness distribution of layer A is larger than the slope Bdif of the layer thickness distribution of layer B continues over 10% to 100% of the number of layers. (2) A laminate sheet comprising a laminated structure in which two or more types of layers with different particle amounts are regularly stacked in 5 to 1001 layers, and on at least one side, a return loss at the maximum peak of a return loss curve in a frequency band of 1 GHz to 1000 GHz is 5.0 dB to 100 dB, and the layer with the greatest particle amount among the layers constituting the laminated structure is called layer B, and the laminated structure is divided into two equal units by a plane perpendicular to the thickness direction, with the larger and smaller thickness ratios of layer B being called laminated unit X and laminated unit Y, respectively, and the thickness ratios (%) of layer B in laminated unit X and laminated unit Y being called laminated unit X and laminated unit Y, respectively, such that tBX-tBY is 5.0% to 90%. (3) The laminate sheet according to (1), wherein ρA×ρB is −1.00 or more and −0.25 or less, where ρA and ρB are the Pearson correlation coefficients of the layer numbers and thicknesses of the A layer and the B layer, respectively. (4) A laminated sheet according to (1), in which, in the laminated structure, when the thickness of the layer A minus the average thickness of the nearest layer B is dT and the difference in dT between adjacent laminated structures is ddT, the section in which the absolute value of the Spearman's rank correlation coefficient between the layer number of the laminated structure and the ddT is 0.50 or more and 1.00 or less covers an area of ​​10% or more and 100% or less based on the number of layers. (5) The laminated sheet according to any one of (1) to (4), having a conductive layer on one side of the laminated component portion. (6) The laminated sheet according to (5), having a conductive layer on one side of the laminated component portion, and when layer numbers are assigned from the conductive layer toward the opposite side, the Spearman's correlation coefficient between the layer number and the dT is 0.50 or more and 1.00 or less. (7) Let the number of layers of the B layer in the laminated component portion be n, the thickness of the laminated component portion be D, the distance between the B layer located at the k-th position counted from the conductive layer side and the conductive layer be d , , and the thickness of the B layer located at the k-th position counted from the conductive layer side be b k The laminated sheet according to (5) or (6), which satisfies the following formula (1).

[0016]

Equation

[0017] (8) The laminated sheet according to any one of (5) to (7), wherein the conductive path length La (μm) and the relative position A of the dielectric constant center of gravity satisfy 10 - 12×A < La < 100. (9) The laminated sheet according to any one of (5) to (8), wherein the phase angle R at normal incidence and the relative position A of the dielectric constant center of gravity satisfy A×0.31 - 1.40 < R < A×1.58 - 0.60. (10) The surface resistivity of the surface having the conductive layer is 10 -8 Ω / sq or more and 10 2 Ω / sq or less. The laminated sheet according to any one of (5) to (9). (11) The laminated sheet according to any one of (5) to (10), wherein the conductive layer contains at least one of copper, aluminum, iron, silver, and nickel. (12) The laminated sheet according to any one of (1) to (11), wherein the difference in the average value of the reflection attenuation amount in the frequency band of 60 GHz or more and 90 GHz or less between the front and back is 0.1 dB or more and 10 dB or less. (13) A signal transceiver having the laminated sheet according to any one of (1) to (12), and the electromagnetic wave reception angle range is 20° or more and 60° or less. (14) A mobile object having the signal transmitter / receiver according to (13) at least one of the front side, back side, and side surface. [Effects of the Invention]

[0018] The present invention provides a laminate sheet that has excellent electromagnetic wave absorption performance over a wide range of incident angles and is therefore suitable for use as an electromagnetic wave shielding material for reducing false detection and malfunction in communication devices. Furthermore, because the laminate sheet of the present invention has the above characteristics, it can be used suitably as a component for signal transceivers and mobile devices. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 2 is a diagram showing the layer thickness distribution of a laminate sheet according to one embodiment of the present invention. [Figure 2] FIG. 10 is a schematic diagram showing the effect of a dielectric constant gradient structure. [Figure 3] 1 is a schematic cross-sectional view of a laminated component constituting a laminated sheet according to one embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing the layer thickness distribution of a laminate sheet according to one embodiment of the present invention. [Figure 5] FIG. 1 is a diagram showing the layer thickness distribution of a laminated component of a laminated sheet according to one embodiment (Example 1) of the present invention. [Figure 6] FIG. 2 is a diagram showing the layer thickness distribution of the laminated component of the laminated sheet according to one embodiment (Examples 2 and 8) of the present invention. [Figure 7] FIG. 3 is a diagram showing the layer thickness distribution of the laminated component of the laminated sheet according to one embodiment (Example 3) of the present invention. [Figure 8] FIG. 10 is a diagram showing the layer thickness distribution of the laminated component of a laminated sheet according to one embodiment (Example 4) of the present invention. [Figure 9] FIG. 10 is a diagram showing the layer thickness distribution of the laminated component of a laminated sheet according to one embodiment (Example 5) of the present invention. [Figure 10] FIG. 2 is a diagram showing the layer thickness distribution of the laminated component of the laminated sheet according to one embodiment (Examples 6, 7, and 9 to 15) of the present invention. [Figure 11] FIG. 10 is a diagram showing the layer thickness distribution of the laminated component of the laminated sheet according to one embodiment (Example 16) of the present invention. [Figure 12] FIG. 10 is a diagram showing the layer thickness distribution of the laminated component of the laminated sheet according to one embodiment (Example 17) of the present invention. [Figure 13] FIG. 10 is a diagram showing the layer thickness distribution of the laminated component of the laminated sheet according to one embodiment (Example 18) of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The laminate sheet of the present invention will be described in detail below. The laminate sheet of the present invention includes a first laminate sheet of the present invention and a second laminate sheet of the present invention, and both of these may be collectively referred to as the laminate sheet of the present invention.

[0021] 1 is a diagram showing a layer thickness distribution of a laminate sheet according to one embodiment of the present invention. The first laminate sheet of the present invention includes a laminate component in which two or more layers having different particle amounts are regularly stacked in 5 to 1001 layers, and on at least one side, the return loss at the maximum peak of a return loss curve in a frequency band of 1 GHz to 1000 GHz is 5.0 dB to 100 dB, and in a layer thickness distribution of each layer of the laminate component, where the layer with the smallest particle amount is designated as layer A and the layer with the largest particle amount is designated as layer B, the horizontal axis represents the layer number and the vertical axis represents the layer thickness, the section in which the slope Adif of the layer thickness distribution of layer A is larger than the slope Bdif of the layer thickness distribution of layer B continues for 10% to 100% of the number of layers.

[0022] The second laminate sheet of the present invention includes a laminate component in which two or more types of layers having different particle amounts are regularly stacked in 5 to 1001 layers, and at least one side has a return loss of 5.0 dB to 100 dB at the maximum peak of a return loss curve in a frequency band of 1 GHz to 1000 GHz, and the layer with the greatest particle amount among the layers constituting the laminate component is called layer B. When the laminate component is divided into two equal units by a plane perpendicular to the thickness direction, the units with the larger and smaller thickness ratios of layer B are called laminate unit X and laminate unit Y, respectively, and the thickness ratios (%) of layer B in laminate unit X and laminate unit Y are called laminate unit X and laminate unit Y, respectively, the ratio tBX - tBY is 5.0% to 90%.

[0023] In the following, the "maximum peak in the return loss curve in the frequency band of 1 GHz to 1000 GHz" may be simply referred to as the "maximum peak."

[0024] The laminate sheet of the present invention has, on at least one side, a return loss of 5.0 dB or more and 100 dB or less at the maximum peak in a return loss curve in the frequency band of 1 GHz to 1000 GHz. Here, a return loss of less than 5.0 dB at the maximum peak in a return loss curve in the frequency band of 1 GHz to 1000 GHz means that there is a frequency in that frequency band at which the transmittance of electromagnetic waves is higher than 30%. Therefore, a laminate sheet with a return loss of less than 5.0 dB at the maximum peak cannot be said to have sufficient electromagnetic wave absorption performance.

[0025] From the viewpoint of ensuring sufficient electromagnetic wave absorption performance, the return loss at the maximum peak of the laminate sheet of the present invention is preferably 14.0 dB or more, more preferably 20.0 dB or more, and even more preferably 26.0 dB or more. When the return loss at the maximum peak is about 30.0 dB, 99.9% of the incident electromagnetic waves are absorbed, and the laminate sheet can be said to have very high electromagnetic wave absorption performance. From the above viewpoint, the larger the return loss at the maximum peak, the better. There is no particular upper limit, but from the viewpoint of feasibility, it is preferably 100 dB, more preferably 50.0 dB.

[0026] The return loss at the maximum peak can be determined from the return loss measured using the method described below for the frequency bands from 1 GHz to 40 GHz, from 40 GHz to 110 GHz, and from 110 GHz to 1000 GHz (details of the measurement method are described below).

[0027] In the laminate sheet of the present invention, methods for achieving a return loss at the maximum peak of 5.0 dB to 100 dB, or within the above-mentioned preferred range, include, for example, using a fluorine-based high-dielectric-constant resin such as polyvinylidene fluoride or a conductive resin such as polythiophene or polyacetylene in the laminate component, as described below. Other methods include using a resin containing a conductive material, a dielectric material such as titanium oxide, mica, or metal titanate, or a magnetic material such as ferrite, carbonyl iron, or flat metal particles in the laminate component, as described below. When using a conductive material, it is preferable to use a conductive material that is resistant to performance degradation even when exposed to high-frequency electromagnetic waves. It is also preferable to appropriately suppress reflection on the resin surface by adjusting the content (preferable types and content of conductive materials are described below). When using a dielectric material or a magnetic material, it is preferable to increase the content within a range that does not impair the moldability of the laminate sheet (preferable content details are described below). Furthermore, when the layer with the least amount of particles is designated as Layer A and the layer with the most is designated as Layer B, it is also effective to make the slope of the layer thickness distribution of each layer of the laminated composition steeper (details of each layer will be described later) or to increase the number of layers in the laminated composition. These methods may be used in combination as appropriate.

[0028] It is important that the laminate sheet of the present invention includes a laminated component in which two or more layers with different particle amounts are regularly stacked in 5 to 1001 layers. Here, "different particle amounts" can be determined by observing the cross section by the method described below and finding that the difference in particle concentration (volume concentration) between adjacent layers is 10% or more. The particles are preferably made of the aforementioned dielectric material or magnetic material, but the type is not particularly limited as long as they have different electromagnetic properties from the matrix resin.

[0029] Furthermore, in the laminate sheet of the present invention, "two or more types of layers are regularly laminated in 5 to 1001 layers" means that two or more types of layers are laminated in a total of 5 to 1001 layers using a specific repeating unit. For example, if the layers constituting the laminated component are two types, A layer and B layer (sometimes referred to as A and B in the explanation of the layer configuration), examples of the arrangement include (AB)nA and (BA)nB (n is a natural number indicating the number of repetitions, the same applies below). Furthermore, if the layers constituting the laminated component are three types, including A layer, B layer, and C layer, examples of the arrangement include (ABC)nA, (ABCB)nA, (ACBC)nA, (ABAC)nA, (ABCAB)nA, (ABCAC)nA, (ABABC)nA, (ABCBCB)nA, etc. In these arrangements, the arrangement in parentheses is the repeating unit.

[0030] By forming a laminate sheet in this manner, the electromagnetic wave absorption of the laminate sheet can be improved over a wide angular range by utilizing the Maxwell-Wagner effect. Furthermore, an embodiment in which particles are distributed more in specific layers than an embodiment in which particles are distributed uniformly in all layers leads to improved conductivity, permittivity, and magnetic permeability due to increased particle connections and the Maxwell-Wagner effect associated with polarization at the interface between each layer, thereby improving the electromagnetic wave absorption performance of the laminate sheet.

[0031] From the above viewpoint, the total number of layers in the laminated structure is preferably 33 or more, more preferably 51 or more, and particularly preferably 81 or more. From the above viewpoint, the total number of layers in the laminated structure is preferably as large as possible, but from the viewpoint of feasibility, it is 1001.

[0032] From the perspective of enhancing the absorption performance of electromagnetic waves from an oblique direction, when the layer with the least amount of particles among the layers in the laminated component is defined as layer A and the layer with the most amount of particles is defined as layer B, in the layer thickness distribution of each layer of the laminated component depicted with the layer number on the horizontal axis and the layer thickness on the vertical axis, it is important that the section where the slope Adif of the layer thickness distribution of layer A is larger than the slope Bdif of the layer thickness distribution of layer B continues continuously over 10% or more and 100% or less based on the number of layers. From the above perspective, it is preferable that this section continues continuously over 30% or more and 100% or less based on the number of layers, and more preferably 50% or more and 100% or less.

[0033] Here, the layer number is a number assigned in sequence as the first layer, the second layer, the third layer... from one side of the laminated component to each layer with natural numbers. Also, when the R-squared value when linearly approximating the slopes of the layer thickness distributions of five layers is 0.1 or less, it is determined that there is no slope and it is not included in the section where Adif is larger than Bdif. That is, in the case where the layer thickness distribution of the laminated component is as shown in FIG. 1 (assuming that for the 22nd to 30th layers of layer B, the above R-squared is 0.1 or less), for the 1st to 10th layers, Adif < Bdif, so it is outside the above section; for the 9th to 20th layers, Adif > Bdif, so it is within the above section; for the 19th to 31st layers, layer B is determined to have no slope and is outside the above section, and it can be determined that the above section continues continuously over approximately 39% based on the number of layers (in FIG. 1, reference numeral 1 (white circle) represents the thickness of layer A, and reference numeral 2 (black circle) represents the thickness of layer B. For the sake of convenience, symbols are attached only to the first white circle and black circle).

[0034] In addition, when the continuous range of the above section changes by assigning the layer number from the opposite side, the side where the continuous range of the above section becomes larger is adopted. When the section where Adif < Bdif, the section where Adif > Bdif, and the section where there is no slope overlap, the section where Adif > Bdif is prioritized. Also, the layer number standard means that in calculating the above section, it is calculated based on the number of layers rather than the thickness of each layer (for example, if the total number of layers of the laminated component is 100, it means calculating 1 layer as 1% regardless of the magnitude of the thickness of each layer).

[0035] By providing such a layer thickness distribution for the laminated component, a dielectric constant gradient can be achieved in the thickness direction of the laminated sheet. In particular, varying the thickness of layers with a high particle content allows for adjustment of the connections between particles, making it possible to easily achieve a strong dielectric constant gradient with a smaller particle content than in an embodiment where a gradient is simply applied to the particle concentration. The inventors have discovered that by providing a laminated sheet with a laminated component exhibiting such a gradient in layer thickness distribution, a high absorption level can be achieved when electromagnetic waves are incident at an angle. The mechanism behind this is explained using Figure 2 (in Figure 2, reference numeral 3 represents the electromagnetic wave, and reference numeral 4 represents the laminated sheet).

[0036] As shown in Figure 2, by creating a gradient in the dielectric constant due to the gradient in the layer thickness distribution, electromagnetic waves are refracted within the laminate sheet, taking a path similar to that of linear incidence, suppressing changes in characteristics at oblique incidence. The first laminate sheet of the present invention, in which the Adif > Bdif section is continuous for 10% to 100%, differs from the second laminate sheet of the present invention described below in that adjusting the design of a portion of the overall layer structure can improve the absorption performance of electromagnetic waves from oblique directions. Therefore, the first laminate sheet has the advantage of being easy to manufacture and easily usable in combination with layer designs that have other functions.

[0037] In addition, in a layer structure in which the slope of the layer thickness distribution of layer A, Adif, is larger than the slope of the layer thickness distribution of layer B, Bdif, over a continuous interval of 10% to 100% based on the number of layers, for example, when a feed block with fine slits is used, the thickness of each layer can be adjusted by the shape of the slit (length, width), making it easy to achieve any layer thickness. Indicators related to layer structure and thickness distribution are the same unless otherwise specified.

[0038] In the second laminate sheet of the present invention, from the viewpoint of achieving both electromagnetic wave absorption performance and curl resistance and peel resistance, the layer with the highest particle content among the layers constituting the laminate component is designated Layer B, and two units obtained by dividing the laminate component in half along a plane perpendicular to the thickness direction are designated Layer X and Layer Y, respectively. The thickness ratios (%) of Layer B in Layer X and Layer Y are designated Layer XB and Layer YB, respectively. It is important that tBX - tBY is 5.0% or more and 90% or less. A tBX - tBY ratio of 5.0% or more can impart electromagnetic wave absorption performance to the laminate sheet, and a tBX - tBY ratio of 90% or less can minimize the difference in physical properties between the front and back surfaces, thereby reducing curling and peeling. From the above viewpoints, tBX - tBY is preferably 10% or more and 75% or less, more preferably 30% or more and 75% or less, and even more preferably 45% or more and 75% or less. Here, "dividing the laminated component into two equal parts based on the thickness by a plane perpendicular to the thickness direction" means dividing the laminated component by a plane perpendicular to the thickness direction so that the thicknesses of the resulting laminated units are equal. In other words, if there is a gradient in the thickness of each layer, the number of layers included in each laminated unit may differ.

[0039] The following explains tBX-tBY using Figure 3. In Figure 3, reference numeral 4 denotes the laminate sheet, reference numeral 5 denotes the B layer, reference numeral 6 denotes the laminate unit X, reference numeral 7 denotes the laminate unit Y, and reference numeral 8 denotes the plane perpendicular to the thickness direction of the laminate component (sometimes simply referred to as the "plane perpendicular to the thickness direction"). The laminate sheet 4 in Figure 3 is composed of a total of nine layers, including four B layers 5, and is divided into two equal halves by the plane 8 perpendicular to the thickness direction. The unit with the larger thickness ratio of the B layer is designated laminate unit X6, and the unit with the smaller thickness ratio is designated laminate unit Y7. Here, the thickness ratio of the B layer is calculated as the thickness ratio of the B layer to the entire laminate unit, regardless of the number of layers. In this way, laminate unit X6 and laminate unit Y7 are identified, and the thickness ratios (tBX, tBY) of the B layer in each are determined, allowing tBX-tBY to be calculated.

[0040] The inventors discovered that by biasing the thickness ratio of layer B in a laminate unit obtained by bisecting the laminate sheet in a plane perpendicular to the thickness direction, as in the laminate sheet shown in Figure 3, a high absorption amount can be obtained when electromagnetic waves are incident from an oblique direction. The mechanism behind this is thought to be that when the laminate sheet is configured as shown in Figure 3, a dielectric constant gradient can be created throughout the entire laminate structure, causing the electromagnetic waves to refract within the laminate sheet and take a path similar to linear incidence, thereby suppressing changes in characteristics during oblique incidence. The second laminate sheet of the present invention, in which tBX - tBY is 5.0% or more and 90% or less, has the advantage of being less susceptible to defects due to layer disorder, etc., because the dielectric constant is gradient throughout the entire laminate structure.

[0041] The first laminate sheet of the present invention can also be used as the second laminate sheet, and vice versa. In such an embodiment, the laminate sheet can achieve the benefits of both. In this case, the preferred range of the section where Adif is greater than Bdif and the preferred range of tBX - tBY can be determined using the above-mentioned values. To ensure that the section where Adif is greater than Bdif is continuous over 10% to 100% of the number of layers or the preferred range described above, or to ensure that tBX - tBY is 5.0% to 90% or the preferred range described above, it is effective to form a laminate structure with such a layer thickness distribution using the method described below. For example, when using a feed block with fine slits, the thickness of each layer can be adjusted by the shape (length, width) of the slits, making it easy to achieve any desired layer thickness.

[0042] From the viewpoint of processability, the resin used in the laminate sheet of the present invention is preferably an elastomer resin such as rubber or a thermoplastic resin, more preferably a thermoplastic resin.Examples of thermoplastic resins include polyolefin resins such as polyethylene, polypropylene, poly(1-butene), poly(4-methylpentene), polyisobutylene, polyisoprene, polybutadiene, polyvinylcyclohexane, polystyrene, poly(α-methylstyrene), poly(p-methylstyrene), polynorbornene, and polycyclopentene; polyamide resins such as nylon 6, nylon 11, nylon 12, and nylon 66; vinyl monomer copolymer resins such as ethylene / propylene copolymer, ethylene / vinylcyclohexane copolymer, ethylene / vinylcyclohexene copolymer, ethylene / alkyl acrylate copolymer, ethylene / acrylic methacrylate copolymer, ethylene / norbornene copolymer, ethylene / vinyl acetate copolymer, propylene / butadiene copolymer, isobutylene / isoprene copolymer, and vinyl chloride / vinyl acetate copolymer; and acrylic resins such as polyacrylate, polymethacrylate, polymethyl methacrylate, polyacrylamide, and polyacrylonitrile. Polyester resins typified by polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, etc.; polyether resins typified by polyethylene oxide, polypropylene oxide, polyacrylene glycol, cellulose ester resins typified by diacetyl cellulose, triacetyl cellulose, propionyl cellulose, butyryl cellulose, acetylpropionyl cellulose, nitrocellulose; biodegradable polymers typified by polylactic acid, polybutyl succinate, etc.; and other polymers such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, polyacetal, polyglycolic acid, polycarbonate, polyketone, polyether sulfone, polyether ether ketone, modified polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide, polysiloxane, tetrafluoroethylene resin, trifluoroethylene resin, trifluorochloroethylene resin, tetrafluoroethylene-hexafluoropropylene copolymer, polyvinylidene fluoride, etc.These thermoplastic resins may be used in each layer either singly or as a polymer blend or polymer alloy of two or more types, and may also contain copolymer components as required.

[0043] The particles used in the laminate sheet of the present invention may be of one type or a combination of multiple types. The type of particle is not particularly limited, but considering that it can reduce particle crushing and device damage due to friction between the device and the particles and that the primary particle size is small, it is preferable to select an appropriate non-metallic material. It is also preferable to use a non-metallic material in combination with an inorganic metal-based magnetic material, which will be described later.

[0044] The particles of non-metallic materials preferred for the laminate sheet of the present invention are broadly divided into conductive polymers and inorganic carbons, with inorganic carbons being more preferred from the viewpoint of obtaining high electromagnetic wave absorption performance. Examples of conductive polymer materials include polyacetylene, polyphenylene, polyaniline, polypyrrole, polyisothianaphthene, and polythiophene. These components may be used alone or in combination.

[0045] Examples of inorganic carbon particles that can be used include carbon black (spherical carbon) such as acetylene black, channel black, lamp black, thermal black, ketjen black, and furnace black; carbon nanotubes, which are cylindrical carbons such as single-walled nanotubes, multi-walled nanotubes, and cup-stacked nanotubes; flat carbons such as graphite and graphene; and other particles such as spherical graphite, cylindrical graphite, carbon microcoils, fullerenes, and carbon fibers (long fibers and short fibers). These may be used alone or in combination of two or more types.

[0046] Among these, from the viewpoint of improving the electromagnetic wave absorption performance by charge transfer through improved electrical conductivity, it is preferable to use at least one of carbon black, carbon nanotubes, and carbon fibers. To utilize the effect of particle alignment in the plane direction of the laminated structure and improve the electrical conductivity of the layer containing the particles, it is more preferable to use carbon black, which is likely to develop a primary structure (linear structure). Furthermore, to form a stronger conductive path in the layer direction, it is also preferable to use carbon black, which is likely to develop a linear structure in any direction, in combination with carbon nanotubes or flat carbon, which have a uniform structure and a high aspect ratio. By combining an inorganic carbon material, which is likely to develop a linear structure, with an inorganic carbon material with a fixed structure, the frequency band absorbed by the laminated component can be easily changed by adjusting the ratio of the two particles.

[0047] Carbon black suitable for use in the laminate sheet of the present invention includes carbon black with a dibutyl phthalate (DBP) oil absorption of 150 mL / 100 g or more. DBP oil absorption is an index showing the degree of development of the linear structure of carbon black. A high DBP oil absorption value indicates that carbon black particles are more likely to be connected in a linear chain, resulting in the presence of many voids between the linear structures. Therefore, the higher the DBP oil absorption of carbon black, the easier it is to form conductive paths even with a smaller amount, thereby increasing the conductivity of the laminate component. From the above perspectives, the DBP oil absorption of carbon black is more preferably 200 mL / 100 g or more, and even more preferably 350 mL / 100 g or more.

[0048] When the linear structure of carbon black develops and a conductive path is formed, when an electric field is generated by irradiation with electromagnetic waves, charge accumulates at the interface between the dielectric resin and the particles, converting the electromagnetic energy into thermal energy and thereby demonstrating high electromagnetic wave absorption performance. From this perspective, the upper limit of the DBP oil absorption of carbon black is not particularly limited, but considering the possibility of structure destruction when dispersed in the resin that constitutes the laminate component, it is set to 800 mL / 100 g. DBP oil absorption can be measured in accordance with ASTM D 2414 (2023). Examples of such carbon black that can be used include commercially available carbon blacks such as acetylene black, furnace black, and ketjen black.

[0049] Inorganic carbon-based materials that can be used in combination with the carbon black, which develops a linear structure, preferably include cylindrical carbon nanotubes and flat materials such as graphite, graphene, etc. The advantages of using such particles to obtain the laminate sheet of the present invention are described below. First, the use of such particles enhances the electromagnetic wave absorption performance of the laminate sheet by dispersing high-aspect-ratio particles in the thickness direction due to the Maxwell-Wagner effect. Furthermore, when such particles are used, numerous microscopic dielectric polarizations are formed at the interface between the dielectric resin (e.g., thermoplastic resins with low dielectric constants, such as polyolefin resins, polyester resins, acrylic resins, and vinyl monomer copolymer resins) and the conductive material. Furthermore, the cylindrical or flat material aligns parallel to the planar direction of the laminate component (perpendicular to the thickness direction), resulting in parallel, opposing polarizations like those of a parallel-plate capacitor. As a result, when an electric field is applied by irradiating electromagnetic waves, a large amount of charge is easily accumulated at the interface between the dielectric resin and the particles, thereby increasing the conductivity within the laminate component. Due to these effects, when electromagnetic waves are incident, they are resisted by the particles, and the electromagnetic wave energy is more easily converted into thermal energy, resulting in an improvement in the electromagnetic wave absorption performance of the laminated sheet.

[0050] From the viewpoint of the effect of improving electromagnetic wave absorption performance due to the above mechanism, in the laminate sheet of the present invention, it is preferable that the dielectric polarization formed at the interfaces between the resin and particles within the layers, as well as at the interfaces between each layer in the laminate composition, is aligned in the plane direction of each layer in the laminate composition. The more easily the particles are aligned in the planar direction, the easier it is to obtain a laminate sheet of this type by undergoing a stretching process or the like. Therefore, as mentioned above, it is preferable to use carbon black, which is prone to developing a linear structure, in combination with a cylindrical material with a high aspect ratio. Specifically, an embodiment in which carbon black is used in combination with carbon nanotubes or carbon fibers is particularly suitable.

[0051] The concentration (volume concentration) of particles added to the laminate sheet of the present invention is preferably 2% to 50% or less, more preferably 2% to 30% or less, and particularly preferably 2% to 10% or less, based on the entire laminate sheet being 100%. A particle concentration of 50% or less makes the resin constituting the laminate sheet less brittle, reducing deterioration in formability. Furthermore, a particle concentration of 2% or more reduces deterioration in impedance matching, allows sufficient absorption of electromagnetic waves, and reduces deterioration in directivity.

[0052] In the laminate sheet of the present invention, inorganic metal magnetic materials that can be used in combination with the non-metallic materials described above include metals such as silver, copper, iron, nickel, chromium, aluminum, and zinc, as well as their oxides, nitrides, carbides, borides, oxynitrides, hydroxides, and oxyborides. Transparent conductive metal oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO) can also be used. Metal oxides include magnesium oxide and titanium oxide, and metal hydroxides include calcium hydroxide. Like the carbon material described above, these inorganic metal magnetic materials preferably contain cylindrical or flat materials, as this enhances the electromagnetic wave absorption performance of the laminated structure.

[0053] In the first laminate sheet of the present invention, when the Pearson's correlation coefficients between the layer numbers and thicknesses of the A layer and the B layer are ρA and ρB, respectively, ρA × ρB is preferably -1.00 or more and -0.25 or less. It is preferably -0.83 or more and -0.25 or less. If the gradient of the A layer and the B layer is linear, a higher ρA × ρB will form a clear gradient structure, contributing to improved electromagnetic wave absorption performance. However, if it is not linear, as described below, the optimal value will be slightly greater than -1.

[0054] The fact that ρA × ρB is in the above range indicates that the signs of the inclination of layer A and layer B in the laminated structure are different, and that a clear inclination is formed throughout the laminated structure, resulting in high absorption when electromagnetic waves are incident from an oblique angle. In addition, since there is no problem even if some layer thicknesses are reversed, resistance to defects such as layer disorder is also high.

[0055] In the first laminate sheet of the present invention, when dT is the thickness of layer A minus the average thickness of the nearest layer B, and ddT is the difference between dTs of adjacent laminate structures, the area in which the absolute value of the Spearman's rank correlation coefficient between the layer number of the laminate structure and ddT is 0.50 to 1.00 preferably covers 10% to 100% of the area, based on the number of layers, preferably 30% to 100%, more preferably 50% to 100%, and particularly preferably 70% to 100%.

[0056] The absolute value of the Spearman's rank correlation coefficient between the layer number of the laminated structure and the ddT is between 0.50 and 1.00, indicating that the difference in thickness between layer A and layer B (dT) varies nonlinearly. By varying dT nonlinearly, rather than linearly, it is possible to control the refraction of electromagnetic waves over a wide range of the laminated structure and strongly refract the electromagnetic waves in areas with steep inclinations, thereby changing their direction of propagation. This results in particularly high absorption when the electromagnetic waves are incident obliquely on the laminated sheet surface. Because the refraction angle of electromagnetic waves follows Snell's law, it is preferable to approximate the change in thickness of each layer with an inverse trigonometric function, or, from the perspective of ease of design, with an exponential function close to the inverse trigonometric function.

[0057] From the viewpoint of enhancing electromagnetic wave absorption performance, the laminate sheet of the present invention preferably has a conductive layer on at least one side. Here, "at least one side" means one side or both sides. Furthermore, the conductive layer refers to a layer that is conductive and can reflect electromagnetic waves. In such a laminate sheet, the conductive layer can reflect electromagnetic waves, thereby enhancing the electromagnetic wave absorption performance of the laminate component. In particular, a laminate sheet having a conductive layer on only one side can be arranged so that the conductive layer is on the opposite side to the electromagnetic wave incident surface. When electromagnetic waves incident from the laminate component side are reflected by the conductive layer and pass through the laminate component again, they interfere with electromagnetic waves that subsequently enter the laminate component. This is preferable in that it improves the electromagnetic wave absorption performance of the laminate sheet. On the other hand, from the viewpoint of adjusting the surface impedance, a conductive layer can also be provided on the electromagnetic wave incident surface side.

[0058] The conductive layer constituting the laminate sheet of the present invention may be made of any material capable of reflecting electromagnetic waves. Examples of materials constituting the conductive layer include metals such as aluminum, copper, iron, and gold, alloys such as stainless steel, inorganic carbon particles, and composites of metal or inorganic carbon particles with resin. These materials can be used alone or in combination. The shape and thickness of the conductive layer are not limited and can be appropriately selected depending on the material to be used. The shape can be, for example, a plate-like shape, such as a flat, curved, or hemispherical shape, that matches the shape of the laminate sheet.

[0059] In the laminate sheet of the present invention, from the viewpoint of improving the electromagnetic wave absorption of the laminate sheet, the surface resistivity of the surface having the conductive layer is 10 -8 Ω / sq or more 10 2 It is preferably Ω / sq or less, and more preferably 10 -3 The surface resistivity of the surface having the conductive layer is 10 Ω / sq or more and 10 Ω / sq or less. 2A surface resistivity of Ω / sq or less is preferable from the viewpoint of improving the electromagnetic wave absorption performance of the laminated sheet, since it leads to the conductive layer having sufficient electromagnetic wave reflection performance. In addition, in some applications, the conductive layer may be electrically coupled to the antenna, which may cause unexpected malfunctions. However, it is preferable to set the surface resistivity of the surface having the conductive layer to 10 -8 Such a problem can be alleviated by making the surface resistivity of the conductive layer 10 Ω / sq or more. -8 Ω / sq or more 10 2 Examples of methods for making the surface resistivity Ω / sq or less or within the above-mentioned preferred range include a method of appropriately selecting components for forming the conductive layer and a method of adjusting the thickness. When the conductive layer is present on both sides, the surface resistivity of at least one side should be 10 -8 Ω / sq or more 10 2 If the surface resistivity of the surface having the conductive layer is 10 Ω / sq or less, -8 Ω / sq or more 10 2 It shall be Ω / sq or less.

[0060] The thickness of the conductive layer decreases as the thickness increases, provided that the constituent components remain the same, up to a certain size. The thickness of the conductive layer is preferably 0.1 μm to 100 μm for highly conductive materials such as aluminum and copper, and more than 100 μm and 10 mm or less for moderately conductive materials such as carbon and composites. The highly conductive material preferably contains at least one of copper, aluminum, iron, silver, and nickel.

[0061] It should be noted that the electromagnetic wave absorption performance of the laminate sheet of the present invention varies depending on the side on which the conductive layer is provided (details will be described later). Furthermore, if the adherend to which the laminate sheet of the present invention is attached (such as a signal transceiver or the interior or exterior of a mobile object) contains metal, alloy, carbon, or the like, the adherend can also be used as the conductive layer. However, in this case, the electromagnetic wave absorption performance or absorption frequency may change unexpectedly depending on the adhesive or bonding method, so it is preferable that the laminate sheet itself has a conductive layer on at least one side.

[0062] From the viewpoint of enhancing the electromagnetic wave absorption performance at oblique incidence, the laminate sheet of the present invention has a conductive layer on one side of the laminated component, and when layer numbers are assigned from the conductive layer to the opposite side, the Spearman's correlation coefficient between the layer number and dT is preferably 0.50 or more and 1.00 or less, more preferably 0.60 or more and 1.00 or less, and even more preferably 0.80 or more and 1.00 or less.

[0063] When a laminate sheet of this type is placed so that the surface opposite the conductive layer is the incident surface, the B layer, which has a high particle content, gradually thickens from the conductive layer side toward the incident surface. This means that the relatively high dielectric constant portion is concentrated on the incident surface side, causing the electromagnetic waves to be refracted immediately upon incidence, further improving the electromagnetic wave absorption performance for oblique incidence. Furthermore, by combining this with the layer thickness distribution of the aforementioned nonlinear gradient structure, the highest electromagnetic wave absorption performance can be achieved.

[0064] The laminate sheet of the present invention has a structure in which the number of layers B in the laminated structure is n, the thickness of the laminated structure is D, and the distance between the conductive layer and the B layer located at the kth position counting from the conductive layer side is d k , the thickness of the B layer located at the kth position from the conductive layer side is b k When the above formula is set, it is preferable that the following formula 1 is satisfied. It is more preferable that the formula 2 is satisfied, and it is even more preferable that the formula 3 is satisfied.

[0065]

number

[0066]

number

[0067]

number

[0068] The left side of Equation 1 is a parameter that indicates the location of the center of Layer B as a whole, assuming that the surface of the laminated structure facing the conductive layer is 0 and the opposite surface of the laminated structure is 1. Smaller values ​​indicate closer to the conductive layer, while larger values ​​indicate closer to the opposite surface. The larger the left side of Equation 1, the more concentrated the high-dielectric-constant portion is on the incident surface, enabling electromagnetic waves to be refracted immediately after incidence, further improving the electromagnetic wave absorption performance when electromagnetic waves are incident on the laminated sheet surface from an oblique direction. Furthermore, a gradient structure in the layer thickness distribution is not required; for example, a configuration such as that shown in Figure 4 is possible, which significantly reduces design difficulty and has the advantage of suppressing the effects of defects such as layer disorder. One method for satisfying Equation 1 with the laminated sheet of the present invention is to adjust the center position of Layer B to be biased toward the electromagnetic wave incident surface during layer thickness design.

[0069] The laminate sheet of the present invention preferably has a difference in average return loss between the front and back surfaces in the frequency band of 60 GHz to 90 GHz of 0.1 dB to 10 dB, more preferably 0.5 dB to 10 dB, and even more preferably 2.0 dB to 10 dB.

[0070] The difference in return loss between the front and back sides indicates that the laminated sheet has an electromagnetically asymmetric structure in the thickness direction, and that there is a gradient in the permittivity or permeability of the laminated sheet. Therefore, the refraction effect of the gradient structure can further improve the electromagnetic wave absorption performance at oblique incidence.

[0071] Methods for creating a difference in the return loss between the front and back include, as mentioned above, creating a gradient in the layer thickness, biasing the distribution of layer B, creating a gradient in the thickness of a third layer that is different from both layers A and B, and creating a temperature difference between the front and back during the film-making process (such as the casting process) or offline annealing process to create a difference in the dispersion state of the particles or the crystallization state of the resin.

[0072] In the laminated sheet of the present invention, it is preferable that the conductive path length La (μm) and the relative position A of the dielectric constant center of gravity satisfy 10 - 12×A < La < 100. Here, the conductive path length La (hereinafter sometimes simply referred to as La) represents the length of the portion where the paths are connected in the in-plane direction by the particles in the B layer being connected to each other. When the conductive path length is long, current is easily induced by the electromagnetic wave that has entered the B layer, and the conductivity and dielectric constant are improved. Further, the relative position A of the dielectric constant center of gravity (hereinafter sometimes simply referred to as A) is defined by the following formula 4. Here, Dt is the distance from the surface of the conductive layer close to the laminated component to the surface of the conductive layer far from the laminated component of the laminated component, and the other symbols are the same as those in the above formula 1.

[0073]

Number

[0074] A is a parameter indicating where the center of the entire B layer is, similar to the left side of the above formula 1, but it is different in that when there is a functional layer such as an adhesive layer between the conductive layer and the laminated component, the thickness of the functional layer is considered.

[0075] The inventors of the present invention have found that by prototyping and evaluating laminated sheets with La and A adjusted respectively, when the laminated sheet satisfies a specific relationship between La and A, the electromagnetic wave absorption performance including that from the oblique direction can be improved. Although a higher A enhances the electromagnetic wave absorption performance when an electromagnetic wave is incident on the laminated sheet surface from the oblique direction, even in the region where A is low, by increasing La in accordance with the decrease in A to improve the conductivity and dielectric constant, the refraction immediately after incidence can be increased to enhance the electromagnetic wave absorption performance.

[0076] On the other hand, when La is too large, when electromagnetic waves are incident on the laminated sheet obliquely, the electromagnetic waves are largely reflected by the layer close to the surface, so the electromagnetic waves cannot be absorbed by the inner layer, and the electromagnetic wave absorption performance of the laminated sheet may decrease. Therefore, the relationship between La and A is preferably 10 - 12×A < La < 100, more preferably 15 - 12×A < La < 100, and particularly preferably 20 - 12×A < La < 100.

[0077] Methods for increasing La include using particles with a large aspect ratio, large DBP oil supply amount, and large specific surface area, increasing the shear force received by the resin flow path and die during manufacturing, performing heat treatment to promote self-assembly of the particles, and reducing the thickness of the B layer. However, the methods are not limited to these, and these methods may be appropriately combined.

[0078] The laminated sheet of the present invention preferably satisfies A×0.31 - 1.40 < R < A×1.58 - 0.60 for the phase angle R at normal incidence and the relative position A of the dielectric constant centroid. The phase angle R (hereinafter sometimes simply referred to as R) reflects how much the electromagnetic wave reflected by the conductive layer after passing through the laminated sheet is delayed compared to the case of reflection on the surface of the laminated sheet. The domain of R is -π / 2 or more and less than π / 2.

[0079] The inventors of the present invention found that by prototyping and evaluating a laminated sheet in which R and A were adjusted respectively, when the laminated sheet satisfies the specific relationship between R and A, the electromagnetic wave absorption performance including that from an oblique direction can be improved. Since the electromagnetic wave incident obliquely refracts immediately after incidence by increasing A, the distance that the electromagnetic wave passes through in the laminated sheet becomes longer and the delay becomes larger compared with the case where A is low. Therefore, when the electromagnetic wave incident from the laminated component side is reflected by the conductive layer and passes through the laminated component again, it is shifted from the electromagnetic wave incident later, so the interference effect decreases. By increasing R (delay of electromagnetic wave due to composition, overall thickness, etc.) in accordance with the increase of A (delay of electromagnetic wave due to layer structure), the effect of electromagnetic wave absorption by interference can be maximized even at oblique incidence.

[0080] Therefore, the relationship between R and A is preferably A×0.31 - 1.40 < R < A×1.58 - 0.60, more preferably A×0.31 - 1.30 < R < A×1.58 - 0.70, and particularly preferably A×0.31 - 1.20 < R < A×1.58 - 0.80.

[0081] Methods for increasing R include increasing the thickness of the entire laminated sheet, increasing the dielectric constant of the A layer or / and the B layer, and providing a phase adjustment layer between the laminated component and the conductive layer, etc., but are not limited to these methods, and these methods may be appropriately combined.

[0082] Next, a preferred manufacturing method of the laminated component of the laminated sheet of the present invention will be described below. Of course, the laminated sheet of the present invention is not construed as being limited to examples obtained by such a manufacturing method.

[0083] First, an example of a manufacturing method of the laminated component when using rubber, thermoplastic elastomer, etc. as the resin for each layer will be described below. A predetermined amount of particles is blended into the resin and kneaded with a known apparatus such as a kneader, Banbury mixer, mill mixer, roll mill, jet mill, ball mill, etc. to produce a particle-containing resin. Then, the resin alone and the produced particle-containing resin are each formed into a sheet with a desired thickness by rolling or melt extrusion using a batch press. Then, the sheets corresponding to each layer produced are stacked and pressed or laminated to obtain a desired laminated laminated component. The fusion temperature preferably ranges from 150°C to 400°C, more preferably from 250°C to 380°C, depending on the resin used. Note that the resins used for each layer may be the same or different.

[0084] Next, an example of a method for manufacturing a laminate component when using a thermoplastic resin preferably used in the laminate sheet of the present invention is described below. First, a thermoplastic resin prepared in pellet form and a predetermined amount of particles are melt-kneaded using a twin-screw extruder and extruded into a gut shape. The extruded pellets are then cooled in a water tank and cut with a chip cutter to obtain particle-containing resin pellets. The particles may be dry-blended with the resin and then metered and fed from a hopper, or they may be side-fed into the molten resin using a side feeder from any position in the extruder. The method of adding the particles can be selected appropriately depending on the specific gravity and shape of the particles used. Furthermore, the temperature during melt-kneading is preferably above the melting point of the thermoplastic resin used and below the melting point of the particles.

[0085] Pellets of the thermoplastic resin and particle-containing resin (hereinafter sometimes collectively referred to as thermoplastic resin compositions) that make up each layer are dried in hot air or under vacuum and then fed into separate extruders. Each thermoplastic resin composition is heated and melted in the extruder at a temperature above the melting point of the thermoplastic resin, and discharged at a uniform extrusion rate using a gear pump or the like. Foreign matter and modified substances are removed from each thermoplastic resin composition using a filter or the like. These molten thermoplastic resin compositions are then laminated in a multi-layer lamination device capable of laminating the desired number of layers, molded into the desired shape using a die, and discharged into a sheet. The sheet-like laminate discharged from the die is then cooled and solidified on a cooling body such as a casting drum to obtain a cast sheet.

[0086] Since the cast sheet itself is conductive, a preferred method is to blow air in a slit, spot, or planar manner to bring the cast sheet into close contact with a cooling body and solidify it. It is also preferred to use a pressing roll, such as a nip roll, calendar roll, or polishing roll, to bring the cast sheet into close contact with a cooling body and solidify it. Furthermore, it is also preferred to keep the cooling body and pressing roll at a moderate temperature, from the viewpoints of improving the flatness of the laminated sheet and forming an ordered structure through slow cooling, thereby improving the heat resistance of the resulting laminated sheet. The temperature of the cooling body and pressing roll is preferably 50°C or higher, more preferably 80°C or higher, and particularly preferably 100°C or higher. The upper limit is the melting point of the resin with the lowest melting point used in each layer minus 10°C.

[0087] As mentioned above, multi-manifold dies, feed blocks, static mixers, and the like can be used as multi-layer lamination devices. However, to efficiently obtain the laminated structure of the present invention, it is particularly preferable to use a feed block with fine slits. The use of such a feed block prevents the device from becoming excessively large, reduces the amount of foreign matter generated due to thermal degradation, enables high-precision lamination even when the number of layers is extremely large, and significantly improves lamination accuracy in the width direction compared to conventional techniques. Furthermore, such a feed block allows the thickness of each layer to be adjusted by the shape (length, width) of the slits, making it easy to achieve any desired layer thickness. This facilitates the realization of layer thickness designs in which the interval in which Adif is greater than Bdif is continuous for 10% to 100% of the number of layers, or in which tBX - tBY is 5.0% to 90%. Furthermore, a method of forming a laminate using such a feed block and then stacking the layers through a static mixer to double the number of layers can also be suitably used.

[0088] The cast sheet thus obtained can be biaxially stretched in the longitudinal and width directions as needed. Biaxial stretching can be performed sequentially or simultaneously. If necessary, the sheet can be further stretched in the longitudinal and / or width directions after the biaxial stretching. Here, the longitudinal direction refers to the direction in which the sheet runs during the manufacturing process, and in the case of a sheet roll, this corresponds to the winding direction. The width direction refers to the direction perpendicular to the longitudinal direction within the plane of the sheet.

[0089] First, we will explain the case of sequential biaxial stretching, in which stretching in the longitudinal direction and stretching in the width direction are performed sequentially. Here, stretching in the longitudinal direction refers to stretching to impart molecular orientation to the sheet in the longitudinal direction, and in the case of sequential biaxial stretching, it is usually performed by varying the peripheral speed of the rolls. Stretching in the longitudinal direction may be performed in one stage or in multiple stages using multiple pairs of rolls. The stretching ratio varies depending on the type of resin constituting the sheet, but is usually preferably 1.1 to 15 times, with 1.5 to 4.0 times being particularly preferred. Furthermore, the stretching temperature is preferably set within the range of the glass transition temperature of the resin with the highest glass transition temperature among the resins constituting the sheet to that glass transition temperature + 100°C.

[0090] The uniaxially oriented sheet thus obtained may be subjected to a surface treatment such as corona treatment, flame treatment, or plasma treatment as necessary, followed by the formation of a primer layer to improve adhesion with the film to be laminated on top. In the in-line coating process, the primer layer-forming coating material may be applied to one side, or to both sides simultaneously or sequentially. Forming an appropriate primer layer can improve the adhesion of the conductive layer, which will be described later. Examples of primer components that can be used include curable resins such as urethane acrylate, epoxy acrylate, and polyester acrylate.

[0091] Next, the uniaxially stretched sheet is stretched in the width direction. Stretching in the width direction refers to stretching to impart widthwise orientation to the sheet. This is typically achieved by conveying the uniaxially stretched sheet while holding both widthwise ends of the sheet with multiple clips using a tenter, stretching the uniaxially stretched sheet in the width direction. The stretching ratio varies depending on the type of resin constituting the sheet, but is typically preferably 1.1 to 15 times, with 1.5 to 6.0 times being particularly preferred. The stretching temperature is preferably the glass transition temperature of the thermoplastic resin constituting the sheet with the highest glass transition temperature to that glass transition temperature + 120°C. The biaxially stretched sheet is then subjected to a heat treatment in the tenter from the stretching temperature to the melting point, uniformly annealed, and then cooled to room temperature and wound up. If necessary, relaxation treatment in the longitudinal and / or width directions may be performed during annealing after heat treatment to impart a low orientation angle and thermal dimensional stability to the sheet.

[0092] Next, simultaneous biaxial stretching will be described. In the case of simultaneous biaxial stretching, the cast sheet obtained by the above-mentioned method may be subjected to a surface treatment such as corona treatment, flame treatment, or plasma treatment as necessary, and then imparted with functions such as easy slip, easy adhesion, and antistatic properties by in-line coating. In the in-line coating process, the easy adhesion layer may be applied to one side of the cast sheet, or may be applied to both sides of the cast sheet simultaneously or one side at a time.

[0093] The cast sheet is then introduced into a simultaneous biaxial tenter, where it is conveyed while being held at both ends with clips, and simultaneously stretched in the longitudinal and transverse directions. Simultaneous biaxial tenters include pantograph, screw, drive motor, and linear motor tenters. Drive motor and linear motor tenters are preferred, as they allow for arbitrary stretching ratios and relaxation treatment at any desired location. The stretching ratio varies depending on the type of thermoplastic resin constituting the cast sheet, but is typically preferably 2 to 50 times, more preferably 4 to 20 times, in terms of area ratio (the area ratio is the longitudinal stretching ratio multiplied by the transverse stretching ratio). The stretching speeds in the longitudinal and transverse directions may be the same or different. The stretching temperature is preferably between the glass transition temperature of the thermoplastic resin with the highest glass transition temperature among the thermoplastic resins constituting the cast sheet and the glass transition temperature + 120°C.

[0094] The simultaneously biaxially stretched sheet is preferably subsequently heat-treated in a tenter at a temperature equal to or higher than the stretching temperature and lower than the melting point to impart flatness and dimensional stability. During this heat treatment, it is preferable to instantly relax the sheet in the longitudinal direction immediately before and / or immediately after entering the heat treatment zone to suppress the distribution of the main orientation axis in the width direction. The heat-treated sheet is then uniformly and slowly cooled to room temperature and wound up. If necessary, relaxation treatment may be performed in the longitudinal and / or width directions during the slow cooling from the heat treatment. In this case, it is preferable to instantly relax the sheet in the longitudinal direction immediately before and / or immediately after entering the heat treatment zone.

[0095] The prepared laminate sheet can be bonded to the same laminate sheet or to a laminate sheet of a different thickness or composition via an adhesive sheet, pressure sensitive adhesive sheet, double-sided tape, etc., in order to obtain the desired electromagnetic wave shielding properties.

[0096] Furthermore, to provide the aforementioned conductive layer, a resin / metal layer can be laminated on the laminate sheet of the present invention by metal organic chemical vapor deposition, plasma-enhanced / assisted / activated chemical vapor deposition, ion sputtering, or the like. Also, methods such as spraying or bar coating with a conductive coating material containing metal particles, or laminating a metal foil via an adhesive layer or bonding layer, can be preferably used. From the viewpoint of thinning the laminate sheet, methods using vapor deposition or sputtering are preferred. On the other hand, from the viewpoint of productivity, laminating a metal foil is preferred. When using a molded laminate sheet, methods such as integrally molding a conductive resin by insert molding, or applying a conductive coating material after molding are preferably used.

[0097] Next, the signal transceiver of the present invention will be described. The signal transceiver of the present invention is configured by mounting the laminate sheet of the present invention on a communication device having an electromagnetic wave reception angle range of 20° to 60°. Since the laminate sheet of the present invention has a high absorption amount over a wide range of incident angles, it can be used as a signal transceiver with high accuracy over a wide range compared to conventional technology. A signal transceiver of this type can be obtained by arranging the laminate sheet of the present invention so that the electromagnetic wave reception angle is within the above range.

[0098] Specific applications in which the signal transceiver of the present invention can be preferably used include 4G / 5G communications, wireless LAN, collision prevention (ITS) radar, millimeter wave sensors, etc. In addition, the laminated sheet of the present invention can be mounted on any communication device that uses frequencies in the GHz to THz band, and is not limited to the above.

[0099] Next, a mobile body of the present invention will be described. The mobile body of the present invention has a signal transceiver of the present invention in at least one location on the front side, back side, or side. Because the signal transceiver of the present invention has a wide reception angle range, by providing it in at least one location on the front side, back side, or side of the mobile body, it is possible to accurately detect obstacles approaching the periphery. Specific examples of mobile bodies include manned vehicles such as automobiles and trains, as well as aircraft, ships, drones, and unmanned vehicles. Other mobile bodies that require periphery monitoring can be equipped with and use the signal transceiver of the present invention, and are not limited to the above. [Example]

[0100] The present invention will be described below with reference to examples, but the present invention should not be construed as being limited to these examples. The properties of the laminate sheet were measured by the following methods.

[0101] (Methods for measuring characteristics and methods for evaluating effects and results) The methods for measuring the properties and evaluating the effects in the present invention are as follows.

[0102] (1) Layer thickness, particle concentration, correlation coefficient, Adif, Bdif, tBX, tBY The layer structure of the laminate sheet was determined by observing a sample cut into a cross section using a microtome with a digital microscope, a differential interference microscope, or a scanning electron microscope (SEM) at a magnification appropriate to the layer thickness of each layer constituting the laminate sheet. More specifically, this is as follows. Note that, as described below, the observation and measurement methods differ depending on whether the thickness is 10 μm or more, 1 μm or more but less than 10 μm, or less than 1 μm. However, when the layer thickness of the laminate sheet falls into multiple categories (for example, when layers with a thickness of 10 μm or more and layers with a thickness of 1 μm or more but less than 10 μm are mixed), multiple methods were used based on the thickness.

[0103] When the thickness of each layer making up the laminate sheet was 10 μm or more, the cross section of the laminate sheet was observed and photographed using a Keyence VHX5000 digital microscope at magnifications of 100 to 1000 times. The layer structure was identified and the thickness of each layer was measured using the resulting images. Measurements were performed using the accompanying software (VHX5000_900F), and the vertical distance between layer interfaces where a clear contrast difference was observed was measured as the layer thickness. Data was measured at five random locations, and the average thickness of each layer was used as the actual measurement data.

[0104] When the thickness of each layer making up the laminated sheet was between 1 μm and 10 μm, a Leica differential interference microscope "DMLBHC" was used to observe and photograph the cross section of the laminated sheet at 1000x magnification (10x eyepiece, 100x objective lens). The layer structure was identified and the thickness of each layer was measured from the resulting images. Measurements were performed using particle size analysis software "Macview" (Mountec Co., Ltd.), and the vertical distance between layer interfaces where a clear contrast difference could be detected was measured as the layer thickness. Data was measured at five random locations, and the average value of each layer thickness was used as the actual measurement data.

[0105] When the thickness of each layer constituting the laminated sheet was less than 1 μm, the cross section was subjected to ion milling and Pt deposition using an IM4000PLUS ion milling device manufactured by Hitachi High-Technologies Corporation, and then the cross section was observed and photographed using a JSM-6700F scanning electron microscope (manufactured by Hitachi, Ltd.) at an accelerating voltage of 3.0 kV, a working distance of 8.0 mm, and a magnification of 25,000 times.The layer structure was identified and the thickness of each layer was measured by observing the obtained images and using the microscope's length measurement function.

[0106] The particle concentration was measured using the following procedure. First, cross-sectional images (12 × 9 micrometers, 1200 × 900 pixels) taken with the SEM were imported into ImageJ, and background subtraction (rotational sphere diameter: 2000 pixels), noise removal (median filter, 2 pixels), and binarization were performed to calculate the particle area within the image. The same processing was then performed on five randomly selected fields, and the average particle area ratio relative to the entire layer was taken as the particle concentration (volume concentration). This measurement was performed for each layer.

[0107] The Pearson correlation coefficients (ρA, ρB) of the layer thickness distribution and the Spearman rank correlation coefficient for dT were calculated using the obtained thickness of each layer with the PEARSON function and SPEARMAN function of spreadsheet software (Microsoft Corporation's "Excel" (registered trademark) for Microsoft 365 MSO (version 2308) 32-bit) to two significant digits.

[0108] The slopes of the thickness of the A layer and the B layer (Adif, Bdif) were calculated by inputting the thickness of each layer obtained into the spreadsheet software and using the SLOPE function.

[0109] The B layer bias (tBX-tBY) was calculated by dividing the thickness of each layer obtained in half based on the thickness standard, and determining the layer with the larger and smaller B layer thickness ratio as stack unit X, stack unit Y, respectively. The B layer ratio (%) of stack unit X was defined as tBX, and the B layer ratio (%) of stack unit Y was defined as tBY.

[0110] (2) Return loss, maximum peak frequency For each measurement frequency, the measurement unit and measurement method were changed as follows to obtain the return loss curve of the laminate sheet.

[0111] (2-1) Difference in return loss between the front and back Measurements were performed using a 150mm square sample. Using a Keysight Technologies Vector Network Analyzer (N5290A) and an S-parameter measurement jig, electromagnetic waves were irradiated at an incident angle of 0° in accordance with JIS R 1679 (2007), and S-parameters were measured from 60 to 90GHz (WR-12). 11 and S 22 The difference was evaluated.

[0112] (2-2) Sample pretreatment A bell-jar vacuum deposition apparatus was used to create a pressure of 1.0 x 10 -3 Commercially available aluminum was vapor-deposited on one side of the laminate sheet under conditions of 2 Pa and a filament voltage of 2.6 kV to obtain a conductive layer laminate sample having a vapor-deposited film of 200 nm. However, in Examples 6 to 9, no vapor deposition was performed and the conductive layer laminate sample was used as it was.

[0113] (2-3) Frequency band between 1 GHz and 40 GHz A vector network analyzer (E8361A) manufactured by Agilent Technologies was used. A donut-shaped coaxial waveguide with an outer diameter of 7 mm and an inner diameter of 3.04 mm was used for the 0.5 GHz to 18 GHz frequency band, a rectangular waveguide with a rectangular shape of 4.32 mm x 10.67 mm was used for the 18 to 26.5 GHz frequency band, and a rectangular waveguide with an internal shape of 3.56 mm x 7.11 mm was used for the 26.5 to 40 GHz frequency band. Conductive layer laminate samples were punched and inserted vertically into each of the waveguides with the non-coated surface facing port 1. Measurements were performed at intervals of 200 points for each frequency band. S, which represents the intensity ratio of the reflected electromagnetic wave to the incident electromagnetic wave, was used. 11 is the return loss, and a return loss curve (a curve with return loss on the vertical axis and frequency band on the horizontal axis) was obtained.

[0114] (2-4) Frequency bands above 40 GHz and below 110 GHz Measurements were performed using a 150mm square conductive layer laminate sample. Using a Keysight Technologies Vector Network Analyzer (N5290A) and an S-parameter measurement jig, electromagnetic waves were irradiated at an incident angle of 0° in accordance with JIS R 1679 (2007), and the return loss was measured in the frequency bands of 33 to 50 GHz (WR-22), 50 to 75 GHz (WR-15), and 75 to 110 GHz (WR-10), and a return loss curve was obtained.

[0115] (2-5) Frequency band exceeding 110 GHz and up to 1000 GHz The terahertz laser used was an RM9-THz (Ophir Optronics Solutions, 0.11-30 THz) and the detector was a TeraPyro (Japan Laser, 0.11-30 THz). Prior to sample measurement, a 3 mm aluminum metal plate was placed on the sample to measure the reflected electromagnetic waves at an incident angle of 15°. This was calibrated to a return loss of 0 dB. A 30 mm square conductive layer laminate sample was then placed on the sample and measured. Measurements were performed by directing electromagnetic waves emitted from a terahertz laser at each frequency onto the non-coated surface of the sample at an incident angle of 15° and analyzing the intensity of the reflected laser light. The return loss curve was obtained by dividing the reflected light intensity by the incident light intensity and taking the logarithm, with base 10 as the return loss.

[0116] The return loss curves obtained in (2-3), (2-4), and (2-5) above were analyzed, and the attenuation and frequency at the maximum peak were identified and calculated. For Examples 6 to 9 and Comparative Examples 1 and 2, when the attenuation changed by changing the deposition surface in (2-2), the value with the higher attenuation was used.

[0117] (3)Surface resistivity Measurements were made using a low resistivity meter, Loresta-EP (MCP-T360), manufactured by Mitsubishi Chemical Corporation. An ASP probe (MCP-TP03P) was pressed against the surface of the conductive layer side of a sample cut into a 10 cm square, and the resistance value was measured in accordance with JIS K 7194 (1994). Measurements were made at different measurement positions (n=5), and the average of these values ​​was taken as the surface resistivity of the conductive layer side.

[0118] (4) Average return loss of electromagnetic waves incident on the laminated sheet from an oblique direction (average return loss within a 60° range) The laminated sheet was pre-processed in the same manner as in (2-2), and a return loss curve was obtained in the same manner as in (2-4), except that in addition to the 0° angle of incidence, evaluations were performed at angles of 20°, 40°, and 60°. Vertical polarization, in which the electric field oscillates perpendicular to the plane of incidence of the electromagnetic wave, was used for evaluation. The average value of the attenuation at the maximum peak at each obtained angle of incidence was taken as the average attenuation within a 60° range. Since false detections and malfunctions of communication devices are often caused by electromagnetic waves coming from a wide angle, this value is an indicator of the laminated sheet's ability to reduce false detections and malfunctions of communication devices.

[0119] (5) Intrinsic viscosity (IV) The viscosity average molecular weight was evaluated without adding carbon black. Ortho-chlorophenol was used as the solvent. The intrinsic viscosity [η] (unit: dL / g) at 25°C was determined using an Ubbelohde viscometer. The intrinsic viscosity [η] was calculated using Equation 5 by measuring the specific viscosity [ηsp] at each solution concentration [C] (g / dL).

[0120]

number

[0121] (6) DBP oil absorption The DBP oil absorption was measured in accordance with JIS K 6217-4 (2017). An absorption meter (Absorption meter S-410E, manufactured by Asahi Research Institute) was used for the measurement. The sample weight was 0.05 g and dried at 125°C for 1 hour. The DBP drip rate was 4 ml / min, and the amount of dripping at 70% of the maximum torque was calculated as the DBP absorption (cm 3 / 100g).

[0122] (7) Curl test A 10cm square sample was left standing in an environment of 85℃ and 85% RH for 100 hours. After that, the sample was placed on a flat table and the curl was determined from the height of the lift.

[0123] A: The lift height was less than 2 mm.

[0124] B: The lifting height was 2 mm or more and less than 7 mm.

[0125] C: The lifting height was 7 mm or more.

[0126] (8) Conductive path length (La) The thickness of each layer was calculated using the method described in (1), and the layer with the median thickness among the B layers was identified and selected. If there were multiple layers with the median thickness, the layer closest to the center of the laminated sheet was selected. If the number of B layers was even and the median thickness could not be determined, the thickest of the two layers closest to the median was selected. This selected layer was designated as the B1 layer. After ion milling and Pt deposition of the cross section using a Hitachi High-Technologies Corporation IM4000PLUS ion milling system, the B1 layer was observed and voltage contrast images were taken using a scanning electron microscope (Hitachi, Ltd.) JSM-6700F at an accelerating voltage of 3.0 kV, a working distance of 8.0 mm, and a magnification of 10,000x. Images were taken of the longitudinal-thickness and width-thickness cross sections of the sample, with three randomly selected fields of view for each. (For samples with an unknown longitudinal direction, a cross section in an arbitrary direction-thickness direction and a cross section in a direction perpendicular to the arbitrary direction within the sheet plane in the thickness direction were observed.) In the image thus obtained, the vertical direction of the image was the thickness direction of the sample, and the horizontal direction of the image was the longitudinal direction or width direction of the sample.

[0127] The cross-sectional images (11 × 8.5 μm, 1024 × 768 pixels) were then imported into ImageJ and subjected to alternating contrast enhancement and pixel value subtraction four times, followed by contrast enhancement again. Then, noise reduction (Remove Outliers radius = 10 pixels) was performed. Further processing was performed in the following order: background subtraction (Rotating sphere radius = 10 pixels), noise reduction (Remove Outliers radius = 5 pixels), Otsu's binarization, and noise reduction (Remove Outliers radius = 5 pixels). Skeletonization was then performed, and the area was calculated. The total path length (L) was calculated by dividing the area by the line width.

[0128] Next, the number of aligned pixels in the horizontal direction of the image was calculated using "Orientation J distribution," a function of the ImageJ plugin "Orientation J." The number of aligned pixels at each angle in the image can be calculated, with 0° being the horizontal direction and 90° being the vertical direction. Therefore, pixels aligned at 0° were considered aligned in the in-plane direction. Here, pixels aligned in the 0±2.5° range were considered aligned in the in-plane direction. "Orientation J distribution" was processed using a local window of σ=1, min energy=1%, min coherency=1%, and gradient: cubic spline. The in-plane orientation ratio (A) was calculated by dividing the number of aligned pixels in the in-plane direction by the total number of pixels. The conductive path length (La) was calculated by multiplying the in-plane orientation ratio (A) by the total path length (L). Calculations were performed for each of the six acquired images, and the average value obtained was used as the electrical path length (La) of the laminate sheet.

[0129] (9) Phase angle (R) At the maximum peak frequency obtained in (2), the phase of S11 was set to 0 when evaluating the return loss of a 3 mm thick aluminum metal plate, and an incident angle of 15° was used as normal incidence in the frequency band exceeding 110 GHz and up to 1000 GHz. Next, the aluminum metal plate was removed from the measurement jig, and the sample was set so that the position of the incident surface was the same as when evaluating the aluminum metal plate. The phase of S11 of the sample was obtained and used as the phase angle (R). The domain of the phase angle (R) is greater than or equal to -π / 2 and less than π / 2.

[0130] (10) Identifying the relative position A of the dielectric constant center of gravity As in (1), the cross section of the sample was cut out using a microtome. The number of B layers (n), the thickness of each B layer (b k ), the distance from the conductive layer to each B layer (d k ) and the distance (Dt) from the surface of the conductive layer closest to the laminated component to the surface of the laminated component farthest from the conductive layer was measured and calculated. A was obtained by substituting each value into Equation 4.

[0131]

number

[0132] (Resins, resin compositions, etc. used in the production of laminated sheets) Resin A: Polyethylene terephthalate with an IV of 0.78 Resin B: A mixture of 95 parts by mass of polyethylene terephthalate with an IV of 0.63 and 5 parts by mass of carbon black with a DBP oil absorption of 500 Resin C: A mixture of 97.5 parts by mass of polyethylene terephthalate with an IV of 0.63 and 2.5 parts by mass of carbon black with a DBP oil absorption of 500 Resin D: A mixture of 80 parts by mass of polybutylene terephthalate with an IV of 0.75 and 20 parts by mass of milled carbon fiber with a cut length of 0.1 mm Resin E: Polyvinylidene fluoride resin (Kureha Corporation "KF Polymer" (registered trademark) #1000) Resin F: A mixture of 60 parts by mass of polyethylene terephthalate with an IV of 0.63 and 40 parts by mass of barium titanate particles (BT-01 manufactured by Sakai Chemical Industry Co., Ltd.) Resin G: A mixture of 60 parts by mass of polyethylene terephthalate with an IV of 0.63 and 40 parts by mass of carbonyl iron particles (BASF CIP EW) Resin H: A mixture of 96 parts by mass of polyethylene terephthalate with an IV of 0.63, 3 parts by mass of carbon black with a DBP oil absorption of 500, and 1 part by mass of multi-walled carbon nanotubes with an aspect ratio of 300 Resin I: A mixture of 95 parts by mass of polyethylene terephthalate with an IV of 0.63 and 5 parts by mass of carbon black with a DBP oil absorption of 300 Resin J: A mixture of 95 parts by mass of polyethylene terephthalate with an IV of 0.63 and 5 parts by mass of carbon black with a DBP oil absorption of 180 Resin K: A mixture of 80 parts by mass of polyethylene terephthalate with an IV of 0.78 and 20 parts by mass of isophthalic acid copolymer polyethylene terephthalate with an IV of 0.68 Resin L: Polycarbonate resin with a viscosity average molecular weight of 25,000 The materials containing resin and particles were prepared by side-feeding particles into a dry-blended non-particle raw resin and kneading them in a twin-screw extruder.

[0133] Example 1 Resin A was used on the A layer side, and resin B was used on the B layer side. The prepared resins A and B were fed into separate twin-screw extruders and melt-mixed at 280°C. The screw rotation speed relative to the extrusion rate was set to 0.7 for each twin-screw extruder. The extruded resins were then merged in a 101-piece multi-manifold feed block at a layering ratio of 1.0 (layer A (1):layer B (1)). 101 layers were stacked alternately in the thickness direction, with layer A being the outermost layer on both sides. The thickness design of each layer in the feed block was as shown in Figure 5 (in the figure, only one symbol is assigned; white circles represent layer A and black circles represent layer B. This also applies to Figures 6 to 13). The molten laminate was then fed into a T-die and formed into a sheet, which was then slowly cooled and solidified on a casting drum maintained at a surface temperature of 30°C, and sandwiched between calendar rolls of the same diameter as the casting drum, also maintained at a surface temperature of 30°C, to obtain a 0.5 mm thick laminated portion, which was then used as a laminate sheet. The evaluation results are shown in Table 1.

[0134] Example 2 A laminated sheet was obtained in the same manner as in Example 1, except that the thickness of each layer of the feedblock was designed as shown in Figure 6. The evaluation results are shown in Table 1.

[0135] Example 3 A laminated sheet was obtained in the same manner as in Example 1, except that the thickness of each layer of the feedblock was designed as shown in Figure 7. The evaluation results are shown in Table 1.

[0136] Example 4 A laminated sheet was obtained in the same manner as in Example 1, except that the thickness of each layer of the feedblock was designed as shown in Figure 8. The evaluation results are shown in Table 1.

[0137] Example 5 A laminated sheet was obtained in the same manner as in Example 1, except that the thickness of each layer of the feedblock was designed as shown in Figure 9. The evaluation results are shown in Table 1.

[0138] Example 6 A laminated structure was obtained in the same manner as in Example 1, except that the thickness of each layer of the feed block was designed as shown in Fig. 10. Thereafter, a bell jar-type vacuum deposition apparatus was used to deposit a layer number 1 film on the surface of the laminated structure at a pressure of 1.0 x 10 -3 Commercially available aluminum was evaporated at 200 Pa and a filament voltage of 2.6 kV to form a 500 nm evaporated film, which was then used to prepare a laminated sheet. The evaluation results are shown in Table 1.

[0139] Example 7 A laminate sheet was obtained in the same manner as in Example 6, except that vapor deposition was performed on the surface of the laminated component on the 101th layer side instead of the surface on the 1st layer side. The evaluation results are shown in Table 1.

[0140] Example 8 A laminated sheet was obtained in the same manner as in Example 6, except that the thickness of each layer of the feedblock was designed as shown in Figure 6. The evaluation results are shown in Table 1.

[0141] Example 9 After obtaining a laminated component in the same manner as in Example 6, Resin D was injection molded onto the surface of layer number 1 to a thickness of 2 mm to form a laminated sheet. The mold size was 150 x 150 x 2.5 mm, there were five injection gates (one at the center and one at the midpoint between the center and the vertex), the mold temperature was 80°C, the cylinder temperature was 240°C, and the injection time was 0.5 seconds. The evaluation results are shown in Table 1.

[0142] Example 10 A laminated sheet was obtained in the same manner as in Example 1, except that the thickness of each layer of the feedblock was designed as shown in Figure 10. The evaluation results are shown in Table 1.

[0143] Example 11 A laminate sheet was obtained in the same manner as in Example 10, except that Resin E was used instead of Resin B and the extrusion temperature was 240° C. The evaluation results are shown in Table 1.

[0144] Example 12 A laminate sheet was obtained in the same manner as in Example 10, except that Resin F was used instead of Resin B. The evaluation results are shown in Table 1.

[0145] Example 13 A laminate sheet was obtained in the same manner as in Example 10, except that Resin G was used instead of Resin B. The evaluation results are shown in Table 1.

[0146] Example 14 A laminate sheet was obtained in the same manner as in Example 10, except that Resin C was used instead of Resin B. The evaluation results are shown in Table 1.

[0147] Example 15 A laminated sheet was obtained in the same manner as in Example 10, except that the temperature of the casting drum was set to 80°C to create a temperature difference between the front and back of the sheet during casting. The evaluation results are shown in Table 1.

[0148] Example 16 A laminated sheet was obtained in the same manner as in Example 1, except that the thickness of each layer of the feedblock was designed as shown in Figure 11. The evaluation results are shown in Table 1.

[0149] Example 17 A laminated sheet was obtained in the same manner as in Example 1, except that the thickness of each layer of the feedblock was designed as shown in Figure 12. The evaluation results are shown in Table 1.

[0150] Example 18 A laminated sheet was obtained in the same manner as in Example 1, except that the thickness of each layer of the feedblock was designed as shown in Figure 13. The evaluation results are shown in Table 1.

[0151] (Examples 19, 22, 23, 26, and 27) A laminated sheet was obtained in the same manner as in Example 7, except that the composition and thickness of each layer were as shown in Table 1. The evaluation results are shown in Table 1.

[0152] (Examples 20, 21, 24, 25, 28, and 29) A laminated sheet was obtained in the same manner as in Example 6, except that the composition and thickness of each layer were as shown in Table 1. The evaluation results are shown in Table 1.

[0153] (Comparative Example 1) A laminate sheet was obtained in the same manner as in Example 1, except that the thickness design of each layer of the feedblock was changed so that all layers had the same thickness. The evaluation results are shown in Table 1.

[0154] (Comparative Example 2) A laminate sheet was obtained in the same manner as in Example 1, except that both the A layer side and the B layer side were made of Resin C. The evaluation results are shown in Table 1.

[0155] [Table 1] [Industrial Applicability]

[0156] The present invention provides a laminate sheet that has excellent electromagnetic wave absorption performance over a wide range of incident angles. Because the laminate sheet of the present invention has the above-mentioned properties, it can be suitably used as the interior and exterior of a signal transceiver. Furthermore, because the signal transceiver has a wide detection angle range, it can be suitably used for detecting the periphery of a moving object. [Explanation of symbols]

[0157] 1. Thickness of layer A 2. Thickness of layer B 3. Electromagnetic waves 4 Laminated Sheet 5 B layer 6 Stacking Unit X 7 Stacking unit Y 8 Plane perpendicular to the thickness direction of the laminated structure

Claims

1. a laminated structure portion in which two or more types of layers having different particle amounts are regularly laminated in 5 to 1001 layers, and on at least one surface, the return loss at the maximum peak of a return loss curve in a frequency band of 1 GHz to 1000 GHz is 5.0 dB to 100 dB, A laminated sheet characterized in that, in a layer thickness distribution of each layer of the laminated structure, the horizontal axis is the layer number and the vertical axis is the layer thickness, where the layer with the smallest particle amount is layer A and the layer with the largest particle amount is layer B, the section where the slope Adif of the layer thickness distribution of layer A is larger than the slope Bdif of the layer thickness distribution of layer B continues over 10% to 100% of the number of layers.

2. a laminated structure portion in which two or more types of layers having different particle amounts are regularly laminated in 5 to 1001 layers, and on at least one surface, the return loss at the maximum peak of a return loss curve in a frequency band of 1 GHz to 1000 GHz is 5.0 dB to 100 dB, A laminate sheet characterized in that, when the layer with the largest particle amount among the layers constituting the laminated structure is called layer B, and when the laminated structure is divided into two equal halves based on the thickness by a plane perpendicular to the thickness direction, the units with the larger thickness ratio of layer B are called laminated unit X and laminated unit Y, respectively, and when the thickness ratios (%) of layer B in the laminated unit X and the laminated unit Y are called tXB and tYB, respectively, tBX - tBY is 5.0% or more and 90% or less.

3. 2. The laminate sheet according to claim 1, wherein ρA and ρB are Pearson's correlation coefficients between the layer numbers and thicknesses of the A layer and the B layer, respectively, and ρA×ρB is −1.00 or more and −0.25 or less.

4. 2. The laminate sheet of claim 1, wherein, in the laminated structure, when the thickness of the layer A minus the average thickness of the closest layer B is dT and the difference in dT between adjacent laminated structures is ddT, the section in which the absolute value of the Spearman's rank correlation coefficient between the layer number of the laminated structure and the ddT is 0.50 or more and 1.00 or less covers an area in the range of 10% or more and 100% or less based on the number of layers.

5. The laminate sheet according to claim 1 or 2, wherein a conductive layer is provided on one surface of the laminated component.

6. 6. The laminate sheet according to claim 5, wherein a conductive layer is provided on one side of the laminated component, and when layer numbers are assigned from the conductive layer toward the opposite side, the Spearman's correlation coefficient between the layer number and the dT is 0.50 or more and 1.00 or less.

7. The number of layers of the B layer in the laminated structure is n, the thickness of the laminated structure is D, and the distance between the B layer located at the kth position counting from the conductive layer side and the conductive layer is d ｋ The thickness of the layer B located at the kth position counting from the conductive layer side is b ｋ The laminate sheet according to claim 5, which satisfies the following formula 1 when [Equation 1]

8. 6. The laminate sheet according to claim 5, wherein the conductive path length La (μm) and the relative position A of the dielectric constant center of gravity satisfy 10-12×A<La<100.

9. 6. The laminated sheet according to claim 5, wherein the phase angle R at normal incidence and the relative position A of the dielectric constant center of gravity satisfy A×0.31−1.40<R<A×1.58−0.

60.

10. The surface resistivity of the surface having the conductive layer is 10 －８ Ω / sq or more 10 ２ The laminate sheet according to claim 5, having a modulus of Ω / sq or less.

11. 6. The laminate sheet according to claim 5, wherein the conductive layer comprises at least one of copper, aluminum, iron, silver, and nickel.

12. 3. The laminate sheet according to claim 1, wherein the difference between the average values ​​of return loss in a frequency band of 60 GHz to 90 GHz between the front and back surfaces is 0.1 dB to 10 dB.

13. A signal transceiver comprising the laminate sheet according to claim 1 or 2, wherein the range of angles at which electromagnetic waves are received is 20° or more and 60° or less.

14. A mobile object having the signal transceiver according to claim 13 at at least one of its front side, back side, and side surface.

Images