JP2022024470A - Laminated sheet - Google Patents

Abstract

To provide a laminated sheet having excellent electromagnetic wave shielding, molding, and film forming properties.SOLUTION: A laminated sheet includes a unit having A layers and B layers alternately laminated, with the total number of A and B layers being five or more. At least one of the A and B layers contains particles (particles X) of 0.5 vol.% or more and 90 vol.% or less, which include 3d transition elements of 1 mass% or more and 100 mass% or less. The content of the particles X in the B layers is higher than that in the A layer.SELECTED DRAWING: None

Description

The present invention relates to a laminated sheet having excellent electromagnetic wave shielding properties.

With the progress of communication technology, it is mainly used for metric waves in the hundreds of MHz to several GHz band, which is mainly used for mobile phones and wireless communications, mobile communications such as 4G / 5G, and wireless LAN (Wi-fi) communications. Electromagnetic waves in various frequency bands are used, such as centimeter waves in the band of several GHz to several tens of GHz used, and millimeter waves in the band of several tens to several hundreds of GHz mainly used in automobile collision prevention radars. , Flying in the atmosphere. Electromagnetic waves in the frequency band suitable for the capacity of information, the distance to be transmitted, and the application are selected, but since electromagnetic waves in the similar frequency band are used in various devices and applications, device malfunctions, communication failures, and information There is an increasing need for electromagnetic wave shielding materials that shield electromagnetic waves in order to prevent leakage and the effects on the human body that is sensitive to electromagnetic waves. In particular, in recent years, in order to realize high-speed and large-capacity communication, the development of communication technology using electromagnetic waves in the GHz frequency band is accelerating, and an electromagnetic wave shielding material capable of shielding electromagnetic waves in the frequency band is required.

An electromagnetic wave is a wave composed of two components, an electric field and a magnetic field, and propagates in space while vibrating with each other. The electromagnetic wave shielding material that shields electromagnetic waves is a material that loses or attenuates electromagnetic wave energy by reflecting electromagnetic waves on the surface / inside of the material or absorbing electromagnetic waves inside the material, and it is more effective by combining reflection and absorption. Can be enhanced. For example, the surface reflection of electromagnetic waves can be enhanced by the difference in the electrical resistance value (impedance) between the air interface and the electromagnetic wave shielding material interface, and generally a material with a very low resistance value such as metal (for example, copper) is used. By applying and laminating on the surface of the substrate, electromagnetic wave shielding properties over a wide frequency band can be realized (Patent Document 1).

On the other hand, the electromagnetic wave shield by absorption contains a conductive material and / or a magnetic material in the base material and absorbs the electromagnetic wave entering the inside as an induced current to lose the electromagnetic wave energy, and is a carbon material or ferrite. , Metallic materials containing various 3d transition elements such as iron are contained in a dielectric polymer such as rubber to exhibit absorption performance (Patent Documents 2 to 4). Further, by superimposing layers having different impedances, electromagnetic waves can be multiplely reflected inside the electromagnetic wave shielding material, and interference between the reflected electromagnetic waves and cancellation / loss due to the internal electromagnetic wave absorbing material can be generated (Patent Document 5). ..

In particular, the electromagnetic wave shielding property due to absorption varies depending on the formulation (type, combination, content) of the base material showing dielectric (insulation) and the conductive material contained inside, the thickness of the base material, etc., but the conductive material The arrangement state of the material in the substrate is also an important factor. For example, there is a finding called the Maxwell-Wagner effect, which can enhance the effect of the entire shielding material by arranging the conductive materials in a certain direction and superimposing them side by side in order to improve the conductivity (. Non-Patent Document 1).

Japanese Patent Publication No. 2011-502285 Japanese Unexamined Patent Publication No. 2012-94764 Japanese Unexamined Patent Publication No. 2000-2436115 Japanese Unexamined Patent Publication No. 2004-39703 Japanese Unexamined Patent Publication No. 2018-56492

Z. M. Dang, Prog. Matter. Sci. , 2012, 57, 660-723 Eisaku Yoshida, Journal of the Japanese Society of Applied Magnetics, 2002, vol. 26,893

However, in the electromagnetic wave shielding material using reflection as in Patent Document 1, metal sputtering, vacuum vapor deposition, a technique of coating a paste containing a conductive material or a magnetic material, and the like are used, and a layer coated by these techniques. In addition to short-circuiting of electronic equipment and communication equipment due to peeling off, there may be problems in terms of durability. On the other hand, electromagnetic wave shielding materials using absorption as in Patent Documents 2 and 3 are classified into two types according to the usage pattern, and the evaluation of the effect is also classified into two types. One is a method of using the electromagnetic wave shielding material alone as shown in FIG. 1, and how much the electromagnetic wave shielding material 3 can shield the incident electromagnetic wave 1, in other words, the amount of transmitted electromagnetic wave 2 reduced by the electromagnetic wave shielding material 3 ( The effect is evaluated by the transmission attenuation amount) (Equation (1)). The other is, as shown in FIG. 2, a method in which an electromagnetic wave shielding material is attached to a material capable of reflecting electromagnetic waves (electromagnetic wave reflecting layer). More specifically, the reflected electromagnetic wave 5 when the electromagnetic wave shielding material 3 is bonded to the electromagnetic wave reflecting layer 4 and the incident electromagnetic wave 1 is irradiated, and the reflected electromagnetic wave when the electromagnetic wave reflecting layer 4 is irradiated with the incident electromagnetic wave 1 only. In comparison with 5, the amount of reflected electromagnetic wave 5 (reflection attenuation amount) reduced by the electromagnetic wave shielding material 3 is obtained and the effect is evaluated (Equation (2)). However, many of these techniques can mainly absorb only low frequency electromagnetic waves of 1 GHz or less. This is due to the decrease in magnetic permeability at high frequencies, which is a characteristic of magnetic materials (Sneak's limit).

In the equation (1), _T represents the transmission attenuation amount, E _i represents the electric field strength of the incident electromagnetic wave, and Et represents the electric field strength of the transmitted electromagnetic wave. In equation (2), A is the amount of reflection attenuation, _{Er1 is the electric field strength of the electromagnetic wave reflected when there is an electromagnetic wave shielding material, and Er2 is} the electric field of the electromagnetic wave reflected when there is no electromagnetic wave shielding material. Represents strength.

Therefore, in order to absorb electromagnetic waves in the high frequency band above 1 GHz, it is possible to thicken the electromagnetic wave shielding material, orient the magnetic material (Patent Document 4), and use a magnetic material having a special crystal structure (Patent Document 5). It was necessary. However, when the thickness of the electromagnetic wave shielding material is increased, the electromagnetic wave shielding material becomes stiff. Therefore, applications that require moldability such as winding around a cable or combining an electromagnetic wave shielding material along a housing having a complicated uneven shape. It will be difficult to apply to.

In addition, as a method of aligning the magnetic material to improve the electromagnetic wave absorption performance, there is a method of aligning the flat magnetic material by the shear flow at the time of sheet molding, but if the electromagnetic wave shielding material is thickened in order to improve the absorption performance, the magnetism is increased. The body is not sufficiently oriented and the absorption performance is reduced. That is, the orientation of the magnetic material and the thickness of the electromagnetic wave shielding material have a so-called trade-off relationship, and it is difficult to improve the absorption performance by achieving both of these in the method.

There is also a method to improve the absorption performance in the high frequency band by using a magnetic material with a special crystal structure (such as epsilon iron oxide), but such a magnetic material itself is very expensive and can be applied to a wide range of applications. It was difficult to do. Further, considering the formability and production efficiency of the electromagnetic wave shielding material, continuous sheet formation by melt extrusion using a thermoplastic resin is preferable to a pressed product using a thermoplastic resin, but a high concentration of magnetic material is contained. When forming a single-film sheet, the change in melt viscosity (thixotropic property) of the resin during extrusion becomes strong, and when extrusion-molding into a sheet, uneven discharge occurs, making it difficult to form a sheet with a uniform thickness. There was also a problem that the material became brittle and easily cracked.

An object of the present invention is to solve these problems and to provide a laminated sheet having excellent electromagnetic wave shielding property, moldability, and film forming property.

In order to solve the above problems, the present invention has the following configurations. That is, particles (particles X) containing a unit in which five or more layers A and B are alternately laminated, and at least one of the A layer and the B layer contains 1% by mass or more and 100% by mass or less of a 3d transition element. It is a laminated sheet characterized by containing 0.5% by volume or more and 90% by mass or less, and the B layer contains more particles X than the A layer.

According to the present invention, layers having different contents of particles X are alternately laminated, so that particles X can be highly arranged and dispersed to realize high electromagnetic wave shielding property (transmission attenuation). It is possible to provide a laminated sheet having excellent moldability and film forming property.

It is a schematic diagram which showed the measuring method of the transmission attenuation amount. It is a schematic diagram which showed the measuring method of the reflection attenuation amount. It is a schematic diagram which shows the half width and the electromagnetic wave attenuation of the reflection attenuation peak which has the largest attenuation of the peak top among the peaks obtained by measuring the reflection attenuation peak of a laminated sheet. It is a schematic diagram showing the half width and the electromagnetic wave attenuation of the reflection attenuation peak having the largest attenuation at the peak top among the peaks obtained by measuring the reflection attenuation peak of the laminated sheet in a mode different from that of FIG. be. Among the peaks obtained by measuring the reflection attenuation peak of the laminated sheet in a mode different from those in FIGS. It is a figure. Among the peaks obtained by measuring the reflection attenuation peak of the laminated sheet in a mode different from those in FIGS. It is a figure. It is a schematic diagram explaining the polarization. It is a schematic diagram explaining the linear polarization. It is a schematic diagram explaining the circular polarization. It is a schematic diagram explaining the elliptic polarization.

Hereinafter, the laminated sheet of the present invention will be described in detail. The laminated sheet of the present invention includes a unit in which five or more layers A and B are alternately laminated, and at least one of the A layer and the B layer contains 1% by mass or more and 100% by mass or less of a 3d transition element. It is characterized in that it contains 0.5% by mass or more and 90% by mass or less of particles (particles X), and the B layer contains more particles X than the A layer.

The laminated sheet of the present invention needs to contain particles (particles X) containing 1% by mass or more and 100% by mass or less of a 3d transition element. The particle X refers to a particle in which a 3d transition element occupies 1% by mass or more and 100% by mass or less when all the elements constituting the particle are 100% by mass. Examples of the 3d transition element include scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc. Among them, the particles X preferably contain iron, cobalt, and nickel that easily exhibit ferromagnetism, and particularly preferably contain iron.

The particles X include, in addition to the above 3d transition element itself, a metal oxide, a metal nitride, a metal carbide, a metal boride, a metal oxide nitride, a metal hydroxide, a metal oxide boride, and the like. Organic metal complexes, alloys and the like can also be used. Among them, an organometallic complex is preferable from the viewpoint of maintaining performance in the high frequency band, and for example, carbonyl iron, hexacyanoiron, phosphine iron, amino iron, and derivatives thereof can be preferably used. The particle X may contain only one kind of 3d transition element or may contain a plurality of kinds of 3d transition elements. In the case of containing a plurality of types of 3d transition elements, if the total amount of the 3d transition elements is 1% by mass or more and 100% by mass or less when all the elements constituting the particles are 100% by mass. It is assumed that the particles correspond to the particles X.

In the laminated sheet of the present invention, it is important that at least one of the A layer and the B layer contains 0.5% by volume or more and 90% by volume or less of the particles X, and the B layer contains more particles X than the A layer. Is. Here, "containing 0.5% by volume or more and 90% by volume or less of particles X" means 0.5 volumes of particles satisfying the requirements of the above particles X when all the components constituting the layer are 100% by volume. % Or more and 90% by volume or less. Further, "the B layer contains more particles X than the A layer" means that the content (% by volume) of the particles X in the B layer calculated with 100% by volume of all the components constituting the B layer is the A layer. It means that it is larger than the content (volume%) of the particles X in the layer A calculated by assuming that all the constituent components are 100% by volume.

There are three embodiments in which "at least one of the A layer and the B layer contains 0.5% by volume or more and 90% by volume or less of the particles X, and the B layer contains more particles X than the A layer". Aspects are mentioned. The first aspect is an embodiment in which the amount of particles X in the A layer is 0% by volume or more and less than 0.5% by volume, and the amount of particles X in the B layer is 0.5% by volume or more and 90% by volume or less. In the second aspect, the amount of particles X in the A layer and the amount of particles X in the B layer are both 0.5% by volume or more and 90% by volume or less, and the volume of the B layer is larger than the amount of the particles X in the A layer. This is an embodiment in which the amount of particles X is large. The third aspect is an embodiment in which the amount of particles X in the A layer is 0.5% by volume or more and 90% by volume or less, and the amount of particles X in the B layer exceeds 90% by volume. With such an embodiment, the A layer or the B layer contains a sufficient amount of particles X, and the magnetic properties (permeation attenuation amount) of the two are different. Therefore, electromagnetic wave reflection at the layer interface is realized. can do. Among them, the first aspect and the second aspect are preferable from the viewpoint of suppressing the stacking disorder due to the excess of the particles X and the deterioration of the film forming property and the processability.

If the content of the particles X in both the A layer and the B layer exceeds 90% by mass, the lamination may be disturbed and the film forming stability / processability may be impaired. Further, since the difference in the content of the particles X between the A layer and the B layer is small, the magnetic properties of both are likely to be the same, and the electromagnetic wave shielding property is also inferior. On the contrary, if the content of the particles X in both the A layer and the B layer is less than 0.5% by volume, the electromagnetic wave shielding property may not be sufficiently obtained due to the lack of the particles X. From the viewpoint of achieving both the electromagnetic wave shielding property of the laminated sheet and the film forming stability / processability, the content of the particles X in the B layer is 2% by volume or more and 50 when all the components constituting the layer are 100% by volume. It is preferably 3% by volume or more, more preferably 3% by volume or more and 30% by volume or less, and further preferably 5% by volume or more and 20% by volume or less.

In the laminated sheet of the present invention, when particles X are contained in both the A layer and the B layer, the amount of 3d transition elements (volume%) in the A layer and the B layer are required to give the laminated sheet electromagnetic wave shielding properties. It is required that the amount of 3d transition elements (% by volume) in the medium is not equal. When the amount of 3d transition element (volume%) in the layer A and the amount of 3d transition element (volume%) in the layer B are equal, the layers A and B have different magnetic properties unless a resin having significantly different magnetic properties is used. This is because the magnetic properties of the layers tend to be the same, so that the reflection of electromagnetic waves at the layer interface cannot be obtained, and the electromagnetic wave shielding property (transmission attenuation amount) of the laminated sheet is lowered. The amount of 3d transition elements in each layer can be adjusted, for example, by adjusting the amount of particles X or the amount of 3d transition elements in the particles X.

As a method for evaluating whether or not the particles contained in each layer correspond to the particles X, for example, after peeling off each layer, the particles are extracted with a solvent suitable for dissolving components other than the particles, and the composition thereof is determined. A method for evaluating by a known element analysis method, or a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX) or a transmission electron microscope-energy dispersive X-ray spectroscopy (TEM-) for cross-sections of laminated sheets. A method of analysis using EDX) and the like can be mentioned.

It is important that the laminated sheet of the present invention contains a unit in which five or more layers of A layers and B layers are alternately laminated. Here, the "unit in which five or more layers A and B are alternately laminated" means a configuration in which layers A and B are alternately continuous and have a total of five or more layers. That is, it refers to a state in which resins are laminated according to a regular arrangement of A (BA) n or B (AB) n (n is a natural number of 2 or more). A laminated sheet having a unit in which five or more layers of A layer and B layer are alternately laminated (hereinafter, may be simply referred to as "alternate laminated unit of A layer and B layer") is a layer other than A layer and B layer. Regardless of the presence or absence of the above, all of them correspond to "including a unit in which 5 or more layers of A layer and B layer are alternately laminated". As long as the laminated sheet of the present invention has an alternating laminated unit of A layer and B layer, the outermost layer may be any of layers A and B, and layers other than A layer and B layer, and the outermost layers on both sides are the same. It may be a layer or a layer different from each other, but from the viewpoint of realizing the concept of the laminated sheet of the present invention that enhances the electromagnetic wave shielding property by receiving the resistance of the particles X in the inner layer, the A layer is the outermost layer on both sides. Is preferable. Further, the number of the alternating laminated units of the A layer and the B layer included in the laminated sheet may be one or a plurality.

As a means for obtaining a laminated sheet having an alternating laminated unit of A layer and B layer, as described later, a method of stepwise crimping layers having different compositions to each other and a method of laminating at once via a laminating device. Etc. can be used. Further, on the alternating laminated unit of the A layer and the B layer, a functional layer different from the alternating laminated unit such as another electromagnetic wave reflecting layer or an electromagnetic wave absorbing layer may be formed. In the case of having a plurality of alternating laminated units of A layer and B layer, the plurality of the laminated units can be directly laminated via the adhesive layer or by thermocompression bonding. Further, in the case of having a plurality of alternating laminated units of A layer and B layer, the alternating laminated units having the peak tops of the reflection attenuation peaks are overlapped with each other in different frequency bands, and a desired plurality of frequency bands can be obtained. It may be used as a material for shielding at the same time.

By having the laminated sheet of the present invention having an alternating laminated unit of A layer and B layer, it is possible to improve the electromagnetic wave shielding property targeting a specific frequency band while suppressing the thickness of the entire laminated sheet. Normally, in order to improve the electromagnetic wave shielding property by targeting a specific frequency band, it is necessary to improve the relative magnetic permeability of the entire sheet. In the conventional single film sheet, it is necessary to add a magnetic substance (particle X) at a high concentration or increase the thickness of the sheet in order to reduce the magnetic permeability in the high frequency band due to the limit of Snake. On the other hand, when the alternating laminated unit of the A layer and the B layer is provided, the particles X can be densely confined in each layer and the high magnetic permeability can be maintained even in the high frequency band by orienting the particles X. In particular, when flat particles X are used, the effect of orientation can be remarkably obtained. Further, by setting the magnetic permeability of the A layer and the B layer to different values, the electromagnetic wave is reflected due to the impedance mismatch at the layer interface, so that the electromagnetic wave shielding property (transmission attenuation amount) can be improved.

In order to improve the electromagnetic wave shielding property of the laminated sheet, it is preferable to adjust the relative permittivity in addition to the relative magnetic permeability, and as a method for adjusting the relative permittivity, a method of containing a conductive material (particle Y) is used. Can be used. Even in that case, by forming the A layer and the B layer having different particle Y contents as the alternating laminated unit, the dielectric polarization occurs at the interface between the layers having different relative permittivity, and the current easily passes through the inside of the sheet, so that the electromagnetic wave is electromagnetic wave. Shielding is improved. Further, since the particles Y can be densely confined in each layer, the conductivity in the layer is enhanced, and the particles Y added to the inside are susceptible to loss due to the resistance, and the electromagnetic wave shielding property is higher than that of the conventional product. Can be realized. As a result, it is possible to obtain a laminated sheet having excellent electromagnetic wave shielding properties (reflection attenuation amount, transmission attenuation amount) even if the sheet thickness is thin.

The number of layers in the alternating layering unit of A layer and B layer contained in the laminated sheet is such that the more the layer interface between the layer showing high relative permeability and relative permittivity and the layer showing low relative permeability and relative permittivity, the more electromagnetic waves. Since it is easy to obtain a shielding property, the total number of layers is 13 or more, more preferably 31 layers or more, and further preferably 101 layers or more. The upper limit of the number of layers is preferably 1001 layers from the viewpoint of manufacturing cost, film forming property, and electromagnetic wave shielding performance. By setting the number of laminated units of the A layer and the B layer to 1001 layers or less, it is possible to suppress an increase in manufacturing cost due to an increase in the size of a device such as a feed block having fine slits. At the same time, depending on the dispersed state, shape, and size of the particles X and Y, the disturbance of the layer thickness due to the development of thixotropic property, which is a problem due to the increase in the number of layers and the thinning of the thickness of each layer, is reduced, and electromagnetic waves are generated. It is also possible to maintain the shielding property and the steepness of the electromagnetic wave frequency band to be shielded.

The laminated sheet of the present invention preferably has at least one reflection attenuation peak in the frequency band of 1 MHz to 100 GHz, and more preferably has at least one reflection attenuation peak in the frequency band of 1 GHz to 100 GHz. Whether or not the frequency band of 1 MHz to 100 GHz has at least one reflection attenuation peak can be specifically evaluated by the following procedure. First, using the coaxial waveguide method or the free space method, an electromagnetic wave is applied to a laminated sheet in which a metal reflective plate made of aluminum or the like is combined on the back surface, and the metal plate reflects the electromagnetic wave to reciprocate in the laminated sheet. The intensity of the electromagnetic wave generated is measured and the amount of reflection attenuation in each frequency band is calculated. Next, in the frequency band of 1 MHz to 100 GHz, a reflection attenuation spectrum plotted with the vertical axis as the reflection attenuation amount and the horizontal axis as the frequency is drawn, and it is confirmed whether or not the reflection attenuation amount peak exists in the reflection attenuation spectrum. The details of the measurement method are shown in the section of "(2) Transmission attenuation and reflection attenuation".

In the laminated sheet of the present invention, when the reflection attenuation peak having the largest reflection attenuation at the peak top in the frequency band of 1 MHz to 100 GHz is set as the reflection attenuation peak 1, the reflection attenuation of the reflection attenuation peak 1 is 5 dB. It is preferably 150 dB or less. Here, the peak top usually refers to a position where the slope of the tangent line of the reflection attenuation spectrum is inverted from positive to negative or negative to positive. Reflection attenuation The radio wave attenuation of the peak means the reflection attenuation at the peak top when compared with the baseline. The reflection attenuation peak 1 can be determined from a chart diagram in which the vertical axis is the reflection attenuation amount and the horizontal axis is the frequency in the frequency band of 1 MHz to 100 GHz. By forming a laminated sheet having a reflection attenuation peak within the above range, the laminated sheet can be applied to various products such as high-frequency communication compatible devices and millimeter-wave radars.

Hereinafter, among the peaks obtained by measuring the reflection attenuation peak of the laminated sheet, FIGS. 3 to 6 which are schematic views showing the half-value width of the reflection attenuation peak having the largest attenuation at the peak top and the electromagnetic attenuation amount are shown. Reflection attenuation at the peak top The peak reflection attenuation will be described using. In FIGS. 3 to 6, reference numeral 6 is a baseline, reference numeral 7 is a reflection attenuation peak 1, reference numeral 8 is a peak top of a reflection attenuation peak 1, reference numeral 9 is a reflection attenuation I at the peak top, and reference numeral 10 is reflection. The half price width R of the attenuation peak 1 is shown.

Reflection attenuation The reflection attenuation I in the peak 1 is based on the baseline of the peak when it has a single peak top as shown in FIG. 3, and the peak top and the baseline with respect to the frequency located at the peak top. It can be expressed by the difference in the amount of reflection with. As shown in FIG. 4, there is a case where the baseline is inclined. In such a case, the value obtained by subtracting the inclination of the baseline from the inclination of the reflection attenuation spectrum is positive to negative or negative to positive. The position that is inverted to is the peak top. Even if the peak has a high baseline reflection attenuation as shown in FIG. 5, if it has a specific peak top, the difference in the reflection attenuation between the baseline and the peak top of the peak is the reflection attenuation at the peak top. Can be a quantity. When a spectrum as shown in FIG. 6 having a plurality of peak tops including a shoulder peak is obtained, the reflection attenuation corresponding to the peak top is obtained with respect to the frequency of the peak top of the highest peak among the plurality of peak tops. And the reflection attenuation of the baseline of the entire peak including a plurality of peak tops.

Radio wave attenuation of the reflected attenuation peak The reflected attenuation of the reflected attenuation peak 1 preferably shows a value of 5 dB or more. When the reflection attenuation is less than 5 dB, it means that the transmittance of the electromagnetic wave is higher than 30%, that is, the electromagnetic wave shielding property is insufficient. From the viewpoint of achieving sufficient electromagnetic wave shielding properties, the reflection attenuation of the reflection attenuation peak having the largest reflection attenuation in the laminated sheet of the present invention is preferably 15 dB or more, more preferably 20 dB or more, still more preferably 20 dB or more. It is 30 dB or more. On the other hand, the reflection attenuation amount of the largest peak top attenuation amount The reflection attenuation amount of the peak is about 30 dB, which means that 99.9% of the incident electromagnetic waves are shielded as compared with the electromagnetic wave shielding property of the frequency band before and after the peak. It means that it has a very high electromagnetic wave shielding property. From the viewpoint of electromagnetic wave shielding property of the laminated sheet, the upper limit of the reflection attenuation amount of the reflection attenuation amount peak having the largest attenuation amount at the peak top is not particularly limited, but from the viewpoint of feasibility, it is 150 dB, more preferably 100 dB. be.

The frequency bandwidth in which the attenuation of the reflection attenuation peak with the largest reflection attenuation at the peak top is 5 dB or more and 150 dB or less is a viewpoint of steep and high electromagnetic wave shielding property and reduction of the influence of frequency band fluctuation due to thickness unevenness. Therefore, the width is preferably 1 GHz or more and 20 GHz or less. This narrow bandwidth makes it possible to sharply cut electromagnetic waves in the target band. On the other hand, since this bandwidth is wide, even if the frequency band to be cut fluctuates due to the uneven thickness of the laminated sheet, the influence on the cuttability of the target frequency can be reduced. From the above viewpoint, specifically, the frequency bandwidth in which the reflection attenuation of the reflection attenuation peak 1 is 5 dB or more is more preferably 3.0 GHz or more and 20.0 GHz or less, and further preferably 5.0 GHz or more and 20. It is 0.0 GHz or less.

As described above, the laminated sheet of the present invention aims to obtain a high reflection attenuation amount by controlling the thickness and the content by using the particles X, and the design method thereof will be described in detail. The resin to which the particles X are added exhibits a specific relative permittivity and a specific magnetic permeability depending on the amount of the particles X added and the dispersed state.

The frequency of the reflection attenuation peak 1 can be easily adjusted mainly by changing the thickness of the B layer or / and the A layer, but the reflection attenuation at that frequency is the value of the relative permittivity and the relative permeability. to be influenced. More specifically, by first increasing (thinning) the thickness of the B layer, it is often possible to lower (higher) the frequency showing the reflection attenuation peak more effectively than changing the thickness of the A layer. This is because the B layer contains a large amount of particles X, and the magnetic permeability is often higher than that of the A layer. However, if only one of the layers is made extremely thick or thin, the electromagnetic wave shielding property may be deteriorated due to layer disturbance. Therefore, it is preferable to adjust the thicknesses of the A layer and the B layer at the same time. ..

In order to increase the relative permittivity, it is preferable to add a conductive material (particle Y, details will be described later). Since the particles Y do not affect the relative magnetic permeability so much, the relative permittivity can be controlled independently by adding the particles Y, and the relative permittivity can be easily adjusted. Therefore, it is preferable because it is easy to achieve both thin film thinning and improvement of electromagnetic wave shielding property. Further, by laminating and extruding the layer to which the particles Y are added, the dispersibility of the particles Y is also improved, so that the relative permittivity may be improved.

Examples of the method for increasing the relative magnetic permeability include a method of adding particles X and increasing the amount thereof. However, when the particles X are added, the relative permittivity may also increase (deviation from the design value). Therefore, the relative permeability is first increased in the particles X, and then the relative permittivity is increased in the particles Y. It is preferable to adjust. In particular, when particles X having a flat shape are used, the dispersibility of the particles X is improved by laminating and extruding the layer to which the particles X are added, and the particles are oriented toward the sheet surface, so that the non-magnetic permeability is improved. May be obtained.

It is possible to change the relative permeability by adjusting the composition and / or content of the particles X, but it is difficult to find the optimum content because the relative permittivity also changes accordingly. .. As a result of diligent studies, the inventors have obtained a value obtained by multiplying the longitudinal relative permeability at the reflection attenuation peak 1 by the concentration (volume%) of the particles X in the B layer, and the width at the reflection attenuation peak 1. If the value obtained by multiplying the relative permeability in the direction by the concentration (volume%) of the particles X in the B layer is 0.5 or more and 1000 or less, the relative permeability can be adjusted without significantly changing the relative permittivity. I found it. The longitudinal direction (MD) refers to the direction in which the film travels in the manufacturing process (the winding direction of the film in the case of a film roll), and the width direction (TD) refers to the direction orthogonal to the longitudinal direction in the film plane. .. Hereinafter, the value obtained by multiplying the longitudinal specific permeability at the reflection attenuation peak 1 by the concentration (volume%) of the particles X in the B layer, and the widthwise specific permeability at the reflection attenuation peak 1 are B. The value obtained by multiplying the concentration (% by volume) of the particles X in the layer may be referred to as MD volume permeability and TD volume permeability, respectively. Further, both MD volume permeability and TD volume permeability may be collectively referred to as volume permeability in both directions.

By setting the volumetric permeability in both directions to 0.5 or more, a sufficient amount of reflection attenuation due to the particles X can be realized, and by setting the volumetric permeability in both directions to 1000 or less, the relative permittivity changes due to the contact between the particles X. Errors are suppressed and the design of laminated sheets becomes easier. From the above viewpoint, the volumetric permeability in both directions is more preferably 5 or more and 800 or less.

In the laminated sheet of the present invention, the real and imaginary parts of the relative permittivity in the longitudinal direction at the reflection attenuation peak 1 are set to MDε'and MDε'', respectively, and the relative permittivity in the width direction at the reflection attenuation peak 1 is set. When the real part and the imaginary part are TDε'and TDε'', respectively, it is preferable that both MDε'/ MDε'' and TDε'/ TDε'' are 1 or more and 1000 or less. Although the relative permittivity changes depending on the amount of particles X added, MDε'/ MDε'' can also be obtained by adding a conductive material to the A layer and / or the B layer, or by changing the type and composition of the particles X and the resin. , TDε'/ TDε'' can be adjusted. Each ε ″ mainly affects the reflection of electromagnetic waves at the interface, and each ε ″ affects the phase shift and attenuation of electromagnetic waves inside the layer. From the viewpoint of the electromagnetic wave shielding property of the laminated sheet, it is preferable that both MDε ″ / MDε ″ and TDε ″ / TDε ″ are 1 or more. In addition, since the applicable frequency shifts to the low frequency side in the high ε'region, it is necessary to make an extremely thin film in order to design a thickness that can shield high-frequency electromagnetic waves, and control of variations in electromagnetic wave shielding properties due to stacking disorder. Becomes difficult. Therefore, it is preferable that both MDε ″ / MDε ″ and TDε ″ / TDε ″ are 1000 or less. From the viewpoint of achieving both the electromagnetic wave shielding property of the laminated sheet and the reduction of the laminated disorder, MDε ″ / MDε ″ and TDε ″ / TDε ″ are more preferably 1.5 or more and 100 or less.

In the laminated sheet of the present invention, it is preferable that each particle X is oriented in the plane direction due to the position regulation of the particles X by the lamination from the viewpoint of improving the electromagnetic wave shielding property. Therefore, the thickness of at least one of the layers containing the particles X is preferably 1 nm or more and 30 μm or less, and the thickness of all the layers including the particles X is more preferably 1 nm or more and 30 μm or less. When the thickness of the layer containing the particles X is 1 nm or more, the stacking disorder due to the particles X penetrating the layer is reduced, and the electromagnetic wave shielding property can be kept high. On the other hand, when the thickness of the layer containing the particles X is 30 μm or less, fluctuations in the position and orientation of the particles X in the layer are suppressed, and the effect of position regulation is fully exhibited. The thickness of each layer can be measured by the length measuring function of a microscope using a sample image obtained by cutting out a cross section.

The thickness of the layer containing the particles X is 1.1 times or more and 10 times the average diameter of the contained particles X (or the average diameter of the entire higher-order structure if the particles are present as a higher-order structure). The following is preferable. By setting the thickness of each layer within the range, the particles can be effectively oriented. Here, the average diameter of the particles X means the number-based arithmetic average length diameter described in JIS Z8819-2 (2001). More specifically, the primary particles or higher-order structures are observed using a scanning electron microscope (SEM), a transmission electron microscope, or the like, and the diameter of the circumscribed circle is defined as the particle diameter, which is a value obtained from the number-based average value. Point to. In the case of a laminated film, the number average particle size can be obtained by observing the surface and cross section.

In the laminated sheet of the present invention, it is preferable that the relative permittivity or / and the magnetic permeability gradually increase from the surface layer to the inner layer from the viewpoint of suppressing the surface reflection of electromagnetic waves and increasing the amount of reflection attenuation. One of the means for realizing such an aspect is that the thickness of the B layer is continuously increased from at least one surface layer to the layer in the center of the sheet. Here, "the thickness of the B layer continuously increases from the surface layer to the layer at the center of the sheet" means that the thickness of the B layer is at least one step in the section from the surface layer to the layer at the center of the sheet. It means that the thickness does not increase and the thickness of the B layer does not decrease in the same section. When the surface layer has a layer that strongly reflects electromagnetic waves, the electromagnetic waves do not reach the inner layer of the laminated sheet and receive the resistance of the particles X in the inner layer to improve the electromagnetic wave shielding property. Sex may not be obtained. Therefore, for example, when the A layer is the surface layer, the thickness of the B layer is reduced as it is closer to the surface layer, thereby lowering the relative magnetic permeability / relative permittivity of the surface layer and reducing the relative magnetic permeability / relative permittivity difference at the layer interface. It can be lowered to suppress reflection in a portion close to the surface layer and improve the amount of reflection attenuation. As a means for forming such a laminated structure, for example, a method of using a feed block in which the slit width is adjusted so that the thickness of the B layer continuously increases from the surface layer toward the center can be mentioned.

From the viewpoint of enhancing the electromagnetic wave shielding property (transmission attenuation amount), the laminated sheet of the present invention preferably has a layer having a low ε'inside. That is, the longitudinal relative permittivity of any layer (α layer) located in the middle is MDE (α), and the longitudinal relative permittivity of the layer adjacent to the α layer is MDE (α-1) and MDE (α + 1). ), MDE (α) when the relative permittivity in the width direction in the α layer is TDE (α) and the relative permittivity in the width direction in the layer adjacent to the α layer is TDE (α-1) and TDE (α + 1). ) <MDE (α-1) and MDE (α) <MDE (α + 1), TDE (α) <TDE (α-1) and TDE (α) <TDE (α + 1) It is preferable that one is present, and it is more preferable that both are present.

Here, the "arbitrary layer (α layer) located in the middle" means an arbitrary layer selected from layers other than both outermost layers and layers adjacent thereto. To give a specific example, for example, in a laminated sheet having a two-kind five-layer structure in which the layer structure is A layer / B layer / A layer / B layer / A layer, the central A layer is "arbitrary located in the middle". It becomes a layer (α layer). Further, in the laminated sheet having a two-kind 101-layer structure in which the layer structure is A layer / B layer / A layer / B layer ... / A layer, the third to 99th layers A or B are "intermediate". It can be any layer (α layer) located in.

In addition, "where MDE (α) <MDE (α-1) and MDE (α) <MDE (α + 1), TDE (α) <TDE (α-1) and TDE (α) <TDE (α + 1) "One of the points exists" means that the α layer is selected from all the layers that can be the α layer, and MDE (α), MDE (α-1), MDE (α + 1), and TDE (α). , TDE (α-1), TDE (α + 1), these values are "MDE (α) <MDE (α-1) and MDE (α) <MDE (α + 1)" and "TDE (α + 1)" ) <TDE (α-1) and TDE (α) <TDE (α + 1) ”. To give a specific example, for example, in a laminated sheet having a two-kind five-layer structure in which the layer structure is A layer / B layer / A layer / B layer / A layer, when the central A layer is the α layer. Meet the above requirements. Further, in the laminated sheet having a two-kind 101-layer structure in which the layer structure is A layer / B layer / A layer / B layer ... / A layer, either the third layer to the 99th layer A layer or the B layer. It means that there is at least one layer α that satisfies the above requirements when the above-mentioned layer is set as α layer. Examples of the method having such an embodiment include a method of making a difference in the amount of particles X between the α layer and the layers on both sides thereof.

Where MDE (α) <MDE (α-1) and MDE (α) <MDE (α + 1), where TDE (α) <TDE (α-1) and TDE (α) <TDE (α + 1) The existence of a portion satisfying the existence of any one of them means that there is a portion where the value of ε'in at least one of the longitudinal direction and the width direction is smaller than that of the adjacent layers on both sides. As described above, it is preferable to suppress the reflection of electromagnetic waves near the surface layer of the laminated sheet from the viewpoint of increasing the reflection attenuation of the laminated sheet, but from the viewpoint of improving the transmission attenuation, the electromagnetic wave reflection at the interface of each layer is maximized. It is preferable to make it. Therefore, particularly in the inner layer, it is preferable that the ε'of the adjacent layers is significantly different from each other, and it is preferable that there is a layer in which the ε'is smaller than the layers on both sides adjacent to each other.

It is preferable that the laminated sheet of the present invention exhibits uniaxial anisotropy in the specific magnetic permeability of the laminated sheet from the viewpoint of exhibiting polarization absorption characteristics. Here, "the relative permeability shows uniaxial anisotropy" is arbitrary when the relative permeability of the laminated sheet is measured by linear polarization such as the free space method using a network analyzer or the rectangular waveguide method. It means that the relative magnetic permeability in the direction and the specific magnetic permeability in the direction orthogonal to the direction show different values. As shown in FIG. 7, the polarization means that an electric field or a magnetic field (to be exact, an electric field vector or a magnetic field vector) in a plane perpendicular to the traveling direction travels while vibrating regularly in time and space. An electromagnetic wave that is generated. In FIG. 7, reference numeral 11 is the vibration direction of the electric field vector (only a part thereof is displayed), reference numeral 12 is the traveling direction of the electromagnetic wave, reference numeral 13 is the projection plane, and reference numeral 14 is the locus drawn by the tip of the vibrating electric field vector (reference numeral 14). 13 and 14 are the same in FIGS. 8 to 10 described later). The loci drawn by the tip of the oscillating electric field vector when the polarization is applied to an arbitrary surface drawn in space are various as described below.

Polarization is linear polarization (orthogonal polarization, parallel polarization Fig. 8) and circular polarization (right) depending on the movement when the trajectory drawn by the tip of the vibration of the electric field vector is projected onto a plane perpendicular to the traveling direction of the electromagnetic wave. It is divided into circular polarization, left circular polarization (Fig. 9), and elliptical polarization (Fig. 10). The method for achieving the uniaxial anisotropy of the specific magnetic permeability of the laminated sheet is not particularly limited, and for example, there is a method of orienting needle-shaped, elliptical, or fibrous particles by shearing force or stretching during melt extrusion. In particular, by kneading the particles into a resin having a low viscosity and laminating the particles with a resin having a high viscosity, the orientation of the particles is promoted by the shearing force received from the high-viscosity resin, and thus such an embodiment is preferable.

By using a laminated sheet whose relative permeability shows uniaxial anisotropy, it is possible to show high electromagnetic wave shielding properties only when the vibration direction of the electric field vector coincides with the direction of high relative permeability, especially for linear polarization. Become. Laminated sheets having such characteristics can be preferably used for electromagnetic wave shielding applications of devices such as radars and communication devices that detect an object or perform communication by using polarization.

As described above, it is important to adjust the relative permittivity in the laminated sheet of the present invention from the viewpoint of enhancing the electromagnetic wave shielding property. The method for changing the relative permittivity is not particularly limited, but is achieved, for example, by using a resin exhibiting a high relative permittivity or by incorporating particles Y described later into a resin having high insulating properties. Since the particles Y have excellent conductivity, they function as a conductive material in the laminated sheet.

The particle Y refers to a particle containing at least one element selected from C, Ag, and Au in an amount of 10% by mass or more and 100% by mass or less, and having a content of a 3d transition element of less than 1% by mass. When the content of the 3d transition element of the particle Y is 1% by mass or more, it may be difficult to independently adjust the relative permeability and the relative permittivity for the design of the laminated sheet. More specifically, since the electromagnetic wave shielding design of the laminated sheet is performed by the equations (3) and (4), when the relative permeability and the relative permittivity cannot be adjusted independently, the electromagnetic waves in the desired frequency band are shielded. It may be difficult to design for this, and the variation in electromagnetic wave shielding properties may increase. In the laminated sheet of the present invention, it is preferable that at least one of the A layer and the B layer contains particles Y in an amount of 0.5% by volume or more and 90% by volume or less. When at least one of the A layer and the B layer contains the particles Y in an amount of 0.5% by volume or more, it becomes easy to improve the relative permittivity to the extent that the electromagnetic wave shielding property is affected. When at least one of the A layer and the B layer contains 90% by volume or less of the particles Y, it is possible to reduce the difficulty in forming the laminated sheet.

In the equation (3), A indicates the amount of reflection attenuation, and Z indicates the impedance. In equation (4), Z indicates impedance, μ indicates magnetic permeability, ε indicates dielectric constant, i indicates imaginary unit, f indicates frequency, and d indicates layer thickness.

Examples of the particle Y include conductive metals such as gold and silver, compounds thereof, and organic carbon. In particular, organic carbon, which has a small size of primary particles and is suitable for melt extrusion, is preferable. Examples of organic carbon include carbon black (spherical carbon) such as acetylene black, channel black, lamp black, thermal black, ketjen black, and furnace black, and cylindrical carbon such as single-layer nanotubes, multilayer nanotubes, and cup-stacked nanotubes. Carbon nanotubes, graphite, graphite, flat carbon such as graphene, spherical graphite, cylindrical graphite, carbon microcoils, fullerene, carbon fibers (long fibers, short fibers) and the like can be used. Above all, in order to improve the conductivity of the layer contained in the conductive material by utilizing the effect of orientation and dispersion of the conductive material in the plane direction due to the laminated structure, a primary structure (linear structure) has been developed. It is preferable to use easily conductive carbon black. In addition to carbon black, which develops a structure in any direction, carbon nanotubes with a uniform structure and a high aspect ratio, flat carbon, etc. are used in combination to form a stronger conductive path in the layer direction. It is also preferable to use carbon fiber. By using organic carbon with a well-developed structure and organic carbon with a fixed structure in combination, the ratio of both conductive materials can be distributed and the frequency band shielded by the laminated sheet can be easily changed.

From the viewpoint of enhancing the electromagnetic wave shielding property, the laminated sheet of the present invention preferably has a logarithm (logΩ) of Ω having a base of 10 of 2 or more and 16 or less when the volume resistance of the laminated sheet is Ω. The volume resistance affects the electromagnetic wave shielding property of the laminated sheet. In particular, the larger the logΩ, the easier it is for electromagnetic waves to enter the laminated sheet, and the layer inside the laminated sheet also effectively contributes to the improvement of the electromagnetic wave shielding property. Become. On the other hand, when the logΩ exceeds 16, the electromagnetic wave almost completely passes through the laminated sheet, so that the electromagnetic wave shielding effect itself may be insufficient. From the above viewpoint, the logΩ is more preferably 3 or more and 15 or less, and further preferably 4 or more and 14 or less.

The method of setting the logΩ to 2 or more and 16 or less or the above-mentioned preferable range is, for example, adding / increasing the amount of the conductive material (particle Y) (increasing the logΩ), performing the conductive coating (increasing the logΩ), and using a highly insulating resin. Examples include stacking (decrease in logΩ). In particular, a method of adjusting the amount of the particles Y added and adjusting by laminating a resin having high insulating properties is preferable from the viewpoint of simplicity.

In the laminated sheet of the present invention, the average particle diameter of the particles X is preferably 0.01 μm or more and 10 μm or less from the viewpoint of reducing unevenness in electromagnetic wave shielding and thinning. When the average particle diameter of the particles X is 0.01 μm or more, aggregation is suppressed, so that the particles X are easily dispersed uniformly, and the variation in the electromagnetic wave shielding property is reduced. On the other hand, when the average particle diameter of the particles X is 10 μm or less, it is possible to suppress the occurrence of stacking disorder without making the thickness of each layer excessively large, so that it becomes easy to realize a thin film, and as a result, the laminated sheet. The moldability of the film is also improved. Further, since the average particle diameter of the particles X is 10 μm or less, the formation of voids due to the particles X in the steps of stretching and molding can be suppressed, so that the decrease in the relative magnetic permeability and the relative permittivity due to the voids can be suppressed. Further, as will be described later, the average particle diameter of the particles X is preferably 10 μm or less in order to increase the relative magnetic permeability in the high frequency band.

Here, the average particle size means the number-based arithmetic average length diameter described in JIS Z8819-2 (2001). More specifically, the primary particles or higher-order structures are observed using a scanning electron microscope (SEM), a transmission electron microscope, or the like, and the diameter of the circumscribed circle is defined as the particle diameter, which is a value obtained from the number-based average value. Point to. The particles in the laminated sheet can be measured by observing the surface or the cross section.

In the laminated sheet of the present invention, the ratio of the major axis to the minor axis of the particles X is preferably 1.5 or more from the viewpoint of easily achieving the uniaxial anisotropy of the relative permeability described above. Further, from the same viewpoint, when the cross section when the particle X is cut on a surface perpendicular to the major axis and including the minor axis is surrounded by a rectangle having the minimum area after satisfying the above requirements, the rectangular shape is formed. It is also preferable that the ratio of the short side to the long side is 0.5 or more and 1 or less. When the ratio of the major axis to the minor axis of the particle X is 1.5 or more, it means that the shape of the particle is elongated. Further, when the cross section of the particle X cut on a surface perpendicular to the major axis and including the minor axis is surrounded by a rectangle having the smallest area, the ratio of the short side to the long side of the rectangle is 0.5 or more. A particle of 1 or less means that the particles are flat. Examples of the shape of the particle X satisfying these two requirements include an elongated and flat shape, for example, an elliptical disk or an elliptical column.

By using such particles X, it is easy to achieve the above-mentioned uniaxial anisotropy of relative permeability, and by combining with the laminated structure, a suitable orientation state (position regulation of particles) can be easily achieved, and a high frequency band. The electromagnetic wave shielding property is also improved. In general, magnetic materials generate eddy currents in the high frequency band, so that the relative permeability decreases in the frequency band above a certain level (Sneak limit), but the particles X are flat with an average particle size of 10 μm or less. If this is the case, the generation of eddy currents can be suppressed and high relative permeability can be maintained even in the high frequency band (Non-Patent Document 2).

In order to obtain the desired electromagnetic wave shielding property, the laminated sheets of the present invention may be bonded to each other or laminated sheets having different thicknesses and compositions via an adhesive sheet, an adhesive sheet, double-sided tape or the like. .. The upper limit of the thickness is not particularly limited, but 100 μm is preferable from the viewpoint of ease of handling and the thinning of the finally obtained laminated sheet.

It is also preferable that the laminated sheet of the present invention has an adhesive layer having a thickness of 1 μm or more and 10 mm or less on at least one surface. With such an embodiment, it becomes easy to attach the electromagnetic wave to the irradiated body such as a sensor of electromagnetic waves, and it is possible to suppress the arrival of electromagnetic waves in the frequency band corresponding to noise to the irradiated body. As a result, since the laminated sheet of the present invention functions as an electromagnetic wave shield, it is possible to eliminate adverse effects such as malfunction due to electromagnetic waves in the frequency band corresponding to noise. At this time, when the thickness of the adhesive layer is 1 μm or more, it becomes easy to attach the laminated sheet to the irradiated body. Further, in the case of an application in which a reflection attenuation amount is required, it is also preferable to consider the thickness of the adhesive layer at the stage of designing the laminated sheet from the viewpoint of adjusting the frequency of the reflection attenuation amount peak. In that case, it is preferable that the thickness of the adhesive layer is 1 μm or more so that the adhesive layer can absorb some unevenness of the sticking surface. When the thickness of the adhesive layer is 10 mm or less, it is possible to suppress deterioration of moldability due to an increase in the thickness of the laminated sheet.

Subsequently, the electromagnetic wave-related product of the present invention will be specifically described. The electromagnetic wave-related product of the present invention comprises a laminated sheet of the present invention mounted on any of an electric product, a communication device, and a transportation system. As a preferred embodiment of the present invention, electromagnetic wave prevention used in 4G / 5G communication, wireless LAN, collision prevention (ITS) radar, etc., computer, mobile phone, radio, measuring device, medical device, vehicle bumper, etc. The above-mentioned laminated sheet or the above-mentioned electromagnetic wave is used for the purpose of reducing unnecessary electromagnetic wave radiation from electronic devices, semiconductors, and circuits inside the housing, and preventing device malfunction due to radiation from outside or adjacent devices. Examples thereof include electric products and communication devices having a shield. In addition, if it is an electric product or a communication device that uses a frequency in the GHz band, it is not limited to the above, and the laminated sheet of the present invention can be mounted and used.

Further, as a preferred embodiment of the present invention, a vehicle, an aircraft, a means of transportation such as a ship having the laminated sheet of the present invention, a wall surface of a structure such as a building, a tunnel or a guardrail, a highway, a bridge, a steel tower, a telegraph, a telephone, or the like. Transportation facilities such as communication facilities can also be mentioned. As a method of applying the laminated sheet of the present invention, it is attached to a structure such as a floor, a ceiling, a wall, a window, a pillar, etc. directly via an adhesive or the like, or via another sheet, a shielding plate, a panel, or the like. Etc. can be used. In addition, it can also be used as a wall material or window material for a shielded room to prevent the influence of electromagnetic wave jamming noise from the outside.

Hereinafter, the method for producing a laminated sheet of the present invention will be described with reference to specific examples, but the present invention is not limited to the following aspects.

First, a laminated sheet in the case of using rubber, a thermoplastic elastomer, or the like as a base polymer of a base material will be described as an example. First, a predetermined amount of the desired particles X is added to the base polymer, and the mixture is kneaded and contained in a known device such as a kneader, a Banbury mixer, a mill mixer, a roll mill, a jet mill, or a ball mill to obtain a particle-containing base polymer mixture. obtain. The base polymer alone or the prepared particle-containing base polymer is formed into a sheet having a desired thickness by rolling or melt extrusion by batch pressing, respectively. Then, the prepared sheet corresponding to the layer A and the sheet corresponding to the layer B containing more particles X than this are alternately laminated in a total of 5 or more layers, and pressed or laminated to obtain a laminated sheet. The fusion temperature at this time is preferably 150 ° C. to 400 ° C., more preferably 250 to 380 ° C., although it depends on the type of resin used.

Next, in the laminated sheet in the case of using a thermoplastic resin exhibiting flexibility, which is a preferable resin in the present invention, only the B layer contains particles X, and both the A layer and the B layer do not contain particles Y. A method of manufacturing a product will be described as an example. First, the thermoplastic resin prepared in the form of pellets and a predetermined amount of particles X are kneaded with a twin-screw extruder and extruded into a gut shape, which is cooled in a water tank and cut with a chip cutter to form particles. Form X-containing master pellets. At this time, the particles X may be dry-blended together with the resin and then weighed and fed from the hopper, or may be side-fed into the molten resin from an arbitrary position of the extruder using a side feeder. The feeding method is not limited to the above, and can be appropriately selected according to the specific gravity and shape of the particles to be used.

Then, the thermoplastic resin compositions constituting the A layer and the B layer are dried in hot air or under vacuum, then supplied to separate extruders, and heated and melted in the extruder to a temperature equal to or higher than the melting point of the thermoplastic resin. After that, the extrusion amount is made uniform by a gear pump or the like, the thermoplastic resin composition is discharged, and foreign substances and modified thermoplastic resin are removed by a filter or the like.

Subsequently, these thermoplastic resin compositions are laminated by a multi-layer laminating device capable of laminating a desired number of laminated layers, formed into a desired shape by a die, and discharged into a sheet shape. The sheet-like material discharged from the die is extruded onto a cooling body such as a casting drum and cooled and solidified to become a cast sheet. At this time, since the cast sheet itself exhibits conductivity, air is blown out from a slit-shaped, spot-shaped, or planar device to be brought into close contact with a cooling body such as a casting drum to be rapidly cooled and solidified. It is preferable to use a method of bringing them into close contact with each other for quenching and solidification.

As the multi-layer stacking device, a multi-manifold die, a feed block, a static mixer, or the like can be used, but in particular, in order to efficiently obtain the multi-layer laminated body of the present invention, it is preferable to use a feed block having fine slits. .. When such a feed block is used, the device does not become extremely large, so that the amount of foreign matter generated due to thermal deterioration is small, and high-precision stacking is possible even when the number of stacks is extremely large. In addition, the stacking accuracy in the width direction is significantly improved as compared with the conventional technique. Furthermore, since the thickness of each layer can be adjusted by the shape of the slit (length, width) in this device, it is easy to achieve an arbitrary layer thickness, and particles are laminated by the effect of the resin flow during the laminating process. There is also an advantage that it is easy to orient the particles in the direction of the sheet surface.

When a laminated sheet is produced using a slit type feed block, the thickness and distribution of each layer can be adjusted by changing the length and width of the slit to adjust the pressure balance. The length of the slit is the length of the comb tooth portion that forms a flow path for alternately flowing the A layer and the B layer in the slit plate. Further, a method of forming a laminate with a feed block and then stacking the laminates via a static mixer so as to double the number of laminates can also be preferably used.

The obtained cast sheet can be biaxially stretched in the longitudinal direction and the width direction, if necessary. When biaxial stretching is performed, biaxial stretching may be performed sequentially or biaxial stretching may be performed at the same time. Further, if necessary, re-stretching may be performed in the longitudinal direction and / or the width direction.

First, sequential biaxial stretching, which first stretches in the longitudinal direction and then stretches in the width direction, will be described. Here, the stretching in the longitudinal direction refers to uniaxial stretching for giving the sheet a molecular orientation in the longitudinal direction, and is usually performed by the difference in peripheral speed of the rolls. This stretching may be performed in one step or in multiple steps using a plurality of roll pairs. The draw ratio varies depending on the type of resin, but is usually preferably 1.1 to 7.0 times, and particularly preferably 1.5 to 4.0 times. The stretching temperature is preferably set within the range of the glass transition temperature of the resin constituting the sheet to the glass transition temperature + 100 ° C. and below the melting point of the resin. The uniaxially stretched laminated sheet thus obtained is subjected to surface treatment such as corona treatment, frame treatment, plasma treatment, etc. as necessary, and then a primer layer for improving the adhesion with the film laminated on the upper part. Can also be formed. In the step of in-line coating, the primer layer may be applied to one side, or may be applied to both sides simultaneously or one side at a time.

Stretching in the width direction means stretching to give orientation in the width direction to the sheet, and is usually carried out by using a tenter while gripping both ends of the sheet with clips. The stretching ratio varies depending on the type of resin, but is usually preferably 1.1 to 7.0 times, and particularly preferably 1.5 to 5.0 times. The stretching temperature is preferably from the glass transition temperature of the resin constituting the sheet to the glass transition temperature + 120 ° C. The laminated sheet thus biaxially stretched is heat-treated in a tenter at a stretching temperature or higher and a melting point or lower, slowly cooled uniformly, cooled to room temperature, and wound up. Further, if necessary, a relaxation treatment or the like may be used in combination in the longitudinal direction and / or the width direction when slowly cooling from the heat treatment in order to impart a low orientation angle and thermal dimensional stability of the sheet.

Subsequently, the case of simultaneous biaxial stretching will be described. In the case of simultaneous biaxial stretching, the obtained cast sheet is subjected to surface treatment such as corona treatment, frame treatment, plasma treatment, etc. as necessary, and then slipperiness, adhesiveness, antistatic property, etc. are exhibited. The function may be imparted by in-line coating. In the step of in-line coating, the coat layer may be applied to one side of the sheet, or may be applied to both sides simultaneously or one side at a time.

Next, the cast sheet is guided to the simultaneous biaxial tenter, and the sheet is conveyed while gripping both ends of the sheet with clips, and is simultaneously and / or stepwise stretched in the longitudinal direction and the width direction. Simultaneous biaxial stretching machines (tenters) include pantograph type, screw type, drive motor type, linear motor type, etc., but the stretching ratio can be changed arbitrarily, and relaxation processing should be performed at any location. A drive motor system or a linear motor system that can be used is preferable. The stretching ratio varies depending on the type of resin, but usually, the area ratio is preferably 2.0 to 50 times, and more preferably 4.0 to 20 times. The stretching speed may be the same, or may be stretched in the longitudinal direction and the width direction at different speeds. The stretching temperature is preferably from the glass transition temperature to the glass transition temperature + 120 ° C. of the resin constituting the alternating lamination unit.

In order to impart flatness and dimensional stability to the sheet simultaneously biaxially stretched in this way, it is preferable to continuously heat-treat the sheet in the tenter to have a stretching temperature or higher and a melting point or lower. During this heat treatment, in order to suppress the distribution of the main orientation axis in the width direction, it is preferable to perform the relaxation treatment in the longitudinal direction instantly immediately before and / or immediately after entering the heat treatment zone. After being heat-treated in this manner, it is uniformly slowly cooled, cooled to room temperature, and wound up. Further, if necessary, a relaxation treatment may be performed in the longitudinal direction and / or the width direction when slowly cooling from the heat treatment. Immediately before and / or immediately after entering the heat treatment zone, the relaxation treatment can be performed in the longitudinal direction.

Further, layers having different dielectric constants can be laminated on the outermost surface of the laminated sheet of the present invention for the purpose of enhancing electromagnetic wave transmission or causing electromagnetic wave reflection. At this time, a coating layer containing a material exhibiting suitable conductivity / magnetism may be applied, or different resin layers / mesh layers or the like may be laminated via an adhesive sheet or the like. In addition, sputtering (plane or rotary magnetron sputtering, etc.), evaporation (electron beam evaporation, etc.), chemical vapor deposition, organic metal chemical vapor deposition, plasma strengthening / support / activation chemical vapor deposition, ion sputtering, etc., which are used as sheet metal coating technology. The resin / metal layer can be appropriately laminated according to the required function.

Further, the laminated sheet of the present invention can be made into a laminated sheet that shields only a part of a specific frequency more strongly by combining an electromagnetic wave reflecting layer capable of shielding a wide frequency band. On the other hand, it is also possible to provide a new layer having a low complex dielectric constant for lowering the reflection of electromagnetic waves on the surface on the outermost surface of the laminated sheet to obtain a laminated sheet having a higher effect of absorbing electromagnetic waves. Further, in addition to the latter, it is also preferable that the layer showing a high complex dielectric constant of the laminated sheet shows a layer thickness distribution in which the layer thickness continuously decreases from the surface to the inside of the sheet. Since it is a laminated sheet in which the concentration of the electromagnetic wave suppressing material added to the layer showing a high complex dielectric constant is constant, the thickness of the layer showing a high complex dielectric constant is continuously reduced from the surface layer to the inner layer, so that the inner layer is more electromagnetic wave. The restraining materials are in a state of being tightly connected, and the complex dielectric constant gradually increases. As a result, the electromagnetic wave can be taken into the laminated sheet without being inadvertently reflected, so that the effect of absorbing the electromagnetic wave can be enhanced.

Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited to these Examples. Each characteristic was measured by the following method.

(Characteristic measurement method and effect evaluation method)
The method for measuring the characteristics and the method for evaluating the effect in the present invention are as follows.

(1) Layer thickness, number of laminated layers, laminated structure The layer structure of the laminated sheet was determined by observing a sample obtained by cutting out a cross section using a microtome by a transmission electron microscope (TEM). More specifically, using a transmission electron microscope H-7100FA (manufactured by Hitachi, Ltd.), the cross section of the laminated sheet was observed under the condition of an acceleration voltage of 75 kV, and a cross-sectional photograph was taken. And the thickness of each layer was measured by the length measuring function of the microscope. In some cases, in order to obtain high contrast, a dyeing technique using RuO ₄ or OsO ₄ was used, and the magnification was set to 10,000 times.

(2) Transmission attenuation and reflection attenuation The measurement was performed by changing the measurement unit as follows according to the measurement frequency band.

(2-1) 1 GHz to 40 GHz frequency band The attenuation of the laminated sheet was measured using a vector network analyzer (E8631A) manufactured by Agilent Technologies. The frequency band of 0.5 GHz to 18 GHz is a donut-shaped coaxial waveguide with an outer diameter of φ7 mm and an inner diameter of φ3.04 mm, and the frequency band of 18 to 26.5 GHz is a rectangular lead of 4.32 mm × 10.67 mm. The wave guide was measured using a rectangular waveguide having an internal shape of 3.56 mm × 7.11 mm in the frequency band of 26.5 to 40 GHz. The case where the electric field direction in the waveguide and the MD direction of the laminated sheet were installed in parallel was defined as the attenuation amount in the MD direction, and the case where the TD direction was installed in parallel was defined as the attenuation amount in the TD direction. The measurement interval was set so that 200 points could be measured for each frequency band. In the transmission attenuation measurement, the maximum value of the S parameter value of S ₂₁ , which represents the intensity ratio of the transmitted electromagnetic wave to the incident electromagnetic wave, was taken as the transmission attenuation. When measuring the amount of reflection attenuation, a 3 mm aluminum metal plate was installed on the back surface of the laminated sheet as a sample, and the incident electromagnetic wave was totally reflected when the laminated sheet did not absorb the electromagnetic wave. The reflection attenuation peak was analyzed using the S-parameter value of _S11 , which represents the intensity ratio of the reflected electromagnetic wave to the incident electromagnetic wave.

(2-2) 40-110 GHz frequency band (reflection attenuation)
An aluminum metal plate was attached to the back surface of a 150 mm square laminated sheet to prepare a measurement sample. Using Keycom's lens antenna type oblique incident type electromagnetic wave absorber (electromagnetic wave absorbing material) and reflection attenuation measuring device LAF-26.5B, in accordance with JIS R 1679 (2007), at oblique incident 15 ° Electromagnetic waves were irradiated, and the amount of reflection attenuation was measured for each frequency band of 33 to 50 GHz (WR-22), 50 to 75 GHz (WR-15), and 75 to 110 GHz (WR-10). The case where the electric field direction and the MD direction of the laminated sheet were installed in parallel was defined as the attenuation amount in the MD direction, and the case where the TD direction was installed in parallel was defined as the attenuation amount in the TD direction. Although the value of 33 to 40 GHz is also measured by the measurement method, the measurement data in (2-1) was used for the amount of reflection attenuation in the frequency band of 33 GHz or more and less than 40 GHz.

(2-3) 40 to 110 GHz frequency band (transmission attenuation)
Cut the laminated sheet into a square of 150 mm square, set the lens antenna type oblique incident type electromagnetic wave absorber (electromagnetic wave absorbing material) and reflection attenuation measuring device LAF-26.5 manufactured by Keycom at 180 °, and set between the antennas. The transmission attenuation was analyzed using the S parameter value of S ₂₁ when the laminated sheet was placed perpendicular to the traveling direction of the electromagnetic wave. The case where the electric field direction and the MD direction of the laminated sheet were installed in parallel was defined as the attenuation amount in the MD direction, and the case where the TD direction was installed in parallel was defined as the attenuation amount in the TD direction.

(3) Relative permittivity (ε), relative permeability (μ)
At the time of measuring the transmission attenuation amount, the S parameter value of S ₁₁ was acquired together with the S parameter value of S ₂₁ . Relative permittivity and relative permeability were calculated from the S parameter values using the analysis software (N1500A) manufactured by Keysight Technology Co., Ltd. using the Nicolson-Ross model. The relative permittivity measured with the vibration direction of the electric field vector parallel to the MD direction of the sample was set to MDε'and MDε'', and the relative permeability was set to MDμ'and MDμ''. Similarly, the relative permittivity measured with the vibration direction of the electric field vector and the TD direction of the sample parallel to each other was defined as TDε'and TDε'', and the relative permeability was defined as TDμ'and TDμ''.

(4) Reflection attenuation unevenness The reflection attenuation amount was measured at 5 points at intervals of 30 cm in the longitudinal direction, and the value obtained by dividing the standard deviation of the measurement result by the average value of the measurement result was determined as the reflection attenuation amount unevenness as follows.
〇: Attenuation unevenness is 0 or more and less than 0.1 Δ: Attenuation amount unevenness is 0.1 or more and less than 0.3 ×: Attenuation amount unevenness is 0.3 or more.

(5) Volume Resistance Measurement was performed according to JIS C 2139-3-1 (2018) using a microresistometer (ADVANTEST R8340) and a test device (ADVANTEST R12702A). The applied voltage was adjusted between 1 and 100 V according to the resistance value.

(6) Formability A laminated sheet cut into 250 mm squares was heated to 90 degrees with a vacuum forming machine, and a forming test was performed. As the molding die, a box mold having a height of 1.5 cm, a width of 12 cm, and a depth of 7 cm was used. The quality of the molded product was judged as follows by visual observation.
⊚: There was no residual air at all, and molding was good.
◯: A little air remained in the corners, but the sides were able to follow, and a box-shaped molded product was obtained without large wrinkles.
Δ: Although it was in the shape of a box, air remained at the corners, and the sides could not follow or there were large wrinkles.
X: The shape of the box did not form after the molding test. Or, a tear has occurred.

(Ingredients used in each Example and each Comparative Example)
<Resin>
Polyethylene terephthalate resin: Polyethylene terephthalate resin having a melting point of 254 ° C. and a viscosity IV of 0.63 <particles X>
Carbonyl iron particles: carbonyl iron particles with Fe content 97%, specific gravity 1.49 g / mL, average particle size (D50) 3.5 μm ・ ε iron oxide particles: average particle size 0.1 μm, Fe: Ga: O ( Molar ratio) = 1.98: 0.02: 3.00 ε iron oxide particles / spherical sentust particles: average particle size 0.1 μm, aspect ratio 1.0 spherical sentust particles / flat sentust particles: average particle size 0 .1 μm, flat sentust particles with an aspect ratio of 2.0 <particle Y>
Ketjen black particles A: Ketjen black particles having a DBP oil absorption of 350 mL / 100 g and a bulk density of 100 g / L. Ketjen black particles B: Ketjen black particles having a DBP oil absorption of 500 mL / 100 g and a bulk density of 150 g / L.

(Example 1)
20 parts by mass of carbonyl iron particles were mixed with 80 parts by mass of the polyethylene terephthalate resin, and a master pellet A was prepared using a twin-screw kneading extruder. Polyethylene terephthalate resin was used as the resin constituting the A layer, and the master pellet A was used as the resin composition constituting the B layer. The prepared polyethylene terephthalate resin and master pellet A are each put into two twin-screw extruders in the form of pellets, both are melted at 280 ° C., kneaded and extruded, and merged with a feed block having 61 slits. A laminated sheet having a thickness of 1 mm was prepared by alternately laminating 61 layers in the thickness direction with the outermost layer as the A layer so that the thickness of each layer would be uniform via one stage of a static mixer. The evaluation results of each item are shown in Table 1. The thickness direction means a direction perpendicular to the seat surface.

(Examples 2 to 5, 11 to 13, Comparative Example 4)
A laminated sheet was obtained in the same manner as in Example 1 except that the composition of each layer and the thickness of the laminated sheet were adjusted as shown in Table 1. Table 1 shows the evaluation results of each item. The thickness of the laminated sheet was adjusted by the amount of pellets supplied at the time of extrusion. Hereinafter, the same applies except for Comparative Example 3.

(Example 6)
3 parts by mass of Ketjen black particles A were mixed with 97 parts by mass of polyethylene terephthalate resin, and a master pellet B was prepared using a twin-screw kneading extruder. A laminated sheet was obtained in the same manner as in Example 1 except that the master pellet B was used as the resin composition constituting the layer A and the thickness of the laminated sheet was adjusted as shown in Table 1. Table 1 shows the evaluation results of each item.

(Example 7)
Two parts by weight of Ketjen black particles B were mixed with 98 parts by mass of polyethylene terephthalate resin, and a master pellet C was prepared using a twin-screw kneading extruder. A laminated sheet was obtained in the same manner as in Example 1 except that the master pellet C was used as the resin composition constituting the layer A and the thickness of the laminated sheet was adjusted as shown in Table 1. Table 1 shows the evaluation results of each item.

(Example 8)
The thickness of the laminated sheet is shown by using a feed block showing a layer thickness distribution in which the thickness of the B layer continuously increases from the surface layer to the center and the layer thickness continuously decreases from the center to the opposite surface layer. A laminated sheet was obtained in the same manner as in Example 3 except that the adjustment was made as described in 1. Table 1 shows the evaluation results of each item.

(Example 9)
A laminated sheet having a thickness of 0.5 mm was obtained in the same manner as in Example 1 except that the raw material composition of the B layer was as shown in Table 1, and then this was stretched 2.5 times in the MD direction at 85 ° C. A laminated sheet having a thickness of 0.2 mm was obtained. Table 1 shows the evaluation results of each item.

(Example 10)
A laminated sheet was obtained in the same manner as in Example 6 except that the raw material composition was as shown in Table 1. Table 1 shows the evaluation results of each item.

(Comparative Example 1)
A laminated sheet was obtained in the same manner as in Example 1 except that the feed block had a two-layer structure and three layers were laminated with a static mixer. Table 1 shows the evaluation results of each item.

(Comparative Example 2)
A laminated sheet was obtained in the same manner as in Example 1 except that the B layer was made of polyethylene terephthalate only without adding carbonyl iron particles. Table 1 shows the evaluation results of each item.

(Comparative Example 3)
Master pellets to which 2 parts by mass, 4 parts by mass, 8 parts by mass, 16 parts by mass, 32 parts by mass, and 64 parts by mass of carbonyl iron particles are added to 100 parts by mass of polyethylene terephthalate resin (in order, master pellets D to I). ) Was prepared and pressed to a thickness of 20 μm at 280 ° C. to obtain sheets D to I. Twelve press sheets D, E, F, G, H, I, D, E, F, G, H, and I were stacked in this order and further pressed at a temperature of 180 ° C. to obtain a laminated sheet. Table 1 shows the evaluation results of each item.

Since Comparative Example 3 is press-molded, there is no longitudinal direction and width direction. Therefore, any one direction parallel to the seat surface and the direction orthogonal to this in the seat surface are regarded as the longitudinal direction and the width direction, respectively.

The laminated sheet of the present invention is easily molded and easily formed by laminating two types of layers (A layer and B layer) having different amounts of 3d transition elements, which is difficult to achieve with a conventional single film or a sheet having a low number of laminated layers. Although it is a thin film, it can achieve high electromagnetic wave shielding properties. As a preferred embodiment, since only electromagnetic waves of a specific frequency can be steeply and strongly shielded, malfunction prevention of devices using electromagnetic waves of similar frequency bands and information in large-capacity information communication by high-frequency electromagnetic waves can be prevented. Leakage can be prevented. Specifically, it is suitably used for electronic devices and communication devices using communication technology using electromagnetic waves in the GHz frequency band, vehicles equipped with them as a means of transportation, or transportation facilities including all infrastructures for traffic control. can do.

1: Incident electromagnetic wave 2: Transmitted electromagnetic wave 3: Electromagnetic wave shielding material 4: Electromagnetic wave Reflecting layer 5: Reflected electromagnetic wave 6: Baseline 7: Reflected attenuation peak 1
8: Peak top of reflection attenuation peak 1 9: Reflection attenuation I at peak top
10: Half width R of reflection attenuation peak 1
11: Vibration direction of the electric field vector 12: Travel direction of the electromagnetic wave 13: Projection surface 14: Trajectory drawn by the tip of the vibrating electric field vector

Claims (15)

It contains a unit in which five or more layers A and B are alternately laminated, and at least one of the A layer and the B layer contains 0 particles (particles X) containing 1% by mass or more and 100% by mass or less of a 3d transition element. A laminated sheet containing 5.5% by mass or more and 90% by mass or less, and the B layer contains more particles X than the A layer. The reflection attenuation amount is defined as the reflection attenuation amount peak 1 having at least one reflection attenuation amount peak in the frequency band of 1 MHz to 100 GHz and having the largest reflection attenuation amount at the peak top in the frequency band. The laminated sheet according to claim 1, wherein the reflection attenuation of the peak 1 is 5 dB or more and 150 dB or less. The value obtained by multiplying the longitudinal specific magnetic permeability at the reflection attenuation peak 1 by the concentration (volume%) of the particles X in the B layer, and the widthwise specific magnetic permeability at the reflection attenuation peak 1 are described above. The laminated sheet according to claim 1 or 2, wherein the value obtained by multiplying the concentration (volume%) of the particles X in the B layer is 0.5 or more and 1000 or less. The real and imaginary parts of the relative permittivity in the longitudinal direction at the reflection attenuation peak 1 are MDε'and MDε'', respectively, and the real and imaginary parts of the relative permittivity in the width direction at the reflection attenuation peak 1 are defined as MDε'and MDε'', respectively. TDε'and TDε'', respectively, and MDε'/ MDε'' and TDε'/ TDε'' are both 1 or more and 1000 or less, according to any one of claims 1 to 3. Laminated sheet. The laminated sheet according to any one of claims 1 to 4, wherein at least one of the layers containing the particles X has a thickness of 1 nm or more and 30 μm or less. The laminated sheet according to any one of claims 1 to 5, wherein the thickness of the B layer continuously increases from at least one surface layer to the central layer of the sheet. The longitudinal relative permittivity of any layer (α layer) located in the middle is MDE (α), and the longitudinal relative permittivity of the layer adjacent to the α layer is MDE (α-1) and MDE (α + 1). When the relative permittivity in the width direction in the α layer is TDE (α) and the relative permittivity in the width direction in the layer adjacent to the α layer is TDE (α-1) and TDE (α + 1),
Where MDE (α) <MDE (α-1) and MDE (α) <MDE (α + 1), TDE (α) <TDE (α-1) and TDE (α) <TDE (α + 1) The laminated sheet according to any one of claims 1 to 6, wherein any one of them is present. When the particles Y contain at least one element selected from C, Ag, and Au in an amount of 10% by mass or more and 100% by mass or less and the content of the 3d transition element is less than 1% by mass, the particles Y are referred to as the A layer. The laminated sheet according to any one of claims 1 to 7, wherein at least one of the B layers contains the particles Y in an amount of 0.5% by mass or more and 90% by mass or less. The laminated sheet according to any one of claims 1 to 8, wherein the relative magnetic permeability of the laminated sheet has uniaxial anisotropy. The laminated sheet according to any one of claims 1 to 9, wherein the logarithm of Ω having a base of 10 is 2 or more and 16 or less when the volume resistance of the laminated sheet is Ω. The laminated sheet according to any one of claims 1 to 10, wherein the average particle diameter of the particles X is 0.01 μm or more and 10 μm or less. The laminated sheet according to any one of claims 1 to 11, wherein the ratio of the major axis to the minor axis of the particles X is 1.5 or more. The ratio of the length of the short side to the length of the long side of the rectangle when the cross section of the particle X is cut by a surface perpendicular to the major axis and including the minor axis is surrounded by a rectangle having the smallest area. The laminated sheet according to claim 12, wherein is 0.5 or more and 1.0 or less. The laminated sheet according to any one of claims 1 to 13, wherein an adhesive layer having a thickness of 1 μm or more and 10 mm or less is provided on at least one surface. An electromagnetic wave-related product comprising the laminated sheet according to any one of claims 1 to 14 mounted on any of an electric product, a communication device, and a transportation facility.

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