Electromagnetic wave absorbing flooring material

Abstract

To provide an electromagnetic wave absorbing flooring material which is unlikely to undergo dimensional changes over time and can maintain good electromagnetic wave absorbing properties for a long period of time.SOLUTION: The electromagnetic wave absorbing flooring material has: a surface protective layer 2; a first reflective layer 3 laminated on a rear surface side of the surface protective layer 2 and including a plurality of partial reflective films 31 which are reflective films that reflect electromagnetic waves and are provided at an interval in a surface direction; an interval holding layer 4 laminated on a rear surface side of the first reflective layer 3; a second reflective layer 5 laminated on a rear surface side of the interval holding layer 4 and including a full reflective film 51 which is a reflective film that reflects electromagnetic waves and is provided over the whole in the surface direction; and a rear surface protective layer 6 laminated on a rear surface side of the second reflective layer 5, wherein the interval holding layer 4, the surface protective layer 2 and the rear surface protective layer 6 each have a PVC resin layer containing a vinyl chloride resin.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a flooring material capable of absorbing electromagnetic waves of a desired frequency. [Background technology]

[0002] In recent years, product management has become common using RFID (Radio Frequency Identification). RFID is an automatic recognition system that uses electromagnetic waves to read or rewrite information stored in the IC chip of an RF tag (also called an IC tag), and in Japan, four frequency bands are used: LF band (135KHz or less), HF band (13.56MHz), UHF band (920MHz), and ISM band (2.45GHz). For example, by attaching an RF tag to a product or the packaging material in which the product is packed, and passing the product or packaging material through an RFID gate, the information on the RF tag can be read and the entry and exit of the product can be managed.

[0003] However, when electromagnetic waves are reflected by walls, ceilings, etc., the reflected waves remain in the space, which can deteriorate the communication environment. Patent Document 1 discloses a radio wave absorber comprising: a reflective film made of a conductor; an absorbing material made of a resistor and facing the reflective film; an intermediate layer located between the reflective film and the absorbing material and facing the reflective film and the absorbing material; a first intermediate film made of a conductor and placed in the intermediate layer, facing the reflective film and the absorbing material, and having a hole formed in its center that penetrates from the reflective film side to the absorbing material side; and a second intermediate film made of a conductor, placed in the intermediate layer at the position of the hole in the first intermediate film, and facing the reflective film and the absorbing material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4815174 Summary of the Invention

[0005] However, the radio wave absorber of Patent Document 1 cannot be used as a flooring material, and an electromagnetic wave absorbing flooring material that properly absorbs electromagnetic waves is required. For example, flooring materials used for RFID gates are prone to damage such as scratches and dents and dimensional changes over time because wheels and people pass over the surface of the flooring material. If the flooring material is damaged and / or dimensionally changes, the initially set amount of electromagnetic wave absorption may decrease, or the frequency band of the electromagnetic waves absorbed may change. If the radio wave absorber of Patent Document 1 is used as a flooring material as it is, the electromagnetic wave absorption characteristics may decrease due to damage or dimensional changes over time. [Problem to be solved by the invention]

[0006] An object of the present invention is to provide an electromagnetic wave absorbing flooring material which is durable and resistant to damage and dimensional changes over time, and which can stably maintain good electromagnetic wave absorbing properties for a long period of time. [Means for solving the problem]

[0007] The electromagnetic wave absorbing flooring material of the first embodiment comprises a surface protective layer, a first reflective layer laminated on the back side of the surface protective layer and including a plurality of partial reflective films that are reflective films that reflect electromagnetic waves and are spaced apart in the surface direction, a spacing layer laminated on the back side of the first reflective layer, a second reflective layer laminated on the back side of the spacing layer and including a full reflective film that reflects electromagnetic waves and is provided over the entire surface direction, and a back protective layer laminated on the back side of the second reflective layer, wherein the spacing layer, the surface protective layer and the back protective layer each have a PVC resin layer that contains a vinyl chloride resin.

[0008] The electromagnetic wave absorbing floor material of the second embodiment is the electromagnetic wave absorbing floor material of the first embodiment, wherein the spacing layer has the PVC resin layer and a fiber reinforcement layer interposed in the PVC resin layer. The electromagnetic wave absorbing flooring material of the third embodiment is an electromagnetic wave absorbing flooring material of the first or second embodiment, in which the PVC resin layer of the spacing layer contains the PVC resin and a filler, and the PVC resin layer of the surface protection layer contains the PVC resin but does not contain a filler. The electromagnetic wave absorbing flooring material of the fourth form is an electromagnetic wave absorbing flooring material of the first or second form, in which the PVC resin layer of the spacing layer contains the PVC resin and a filler, and the PVC resin layer of the surface protection layer contains the PVC resin and a filler. Effect of the Invention

[0009] The electromagnetic wave absorbing flooring material of the present invention can maintain good electromagnetic wave absorbing properties for a long period of time. [Brief description of the drawings]

[0010] [Figure 1] Plan view of electromagnetic wave absorbing flooring. [Diagram 2] 2 is a cross-sectional view of the electromagnetic wave absorbing floor material according to one embodiment taken along line II-II in FIG. [Diagram 3] A cross-sectional view of the electromagnetic wave absorbing flooring material taken along line III-III in Figure 1. [Figure 4] 2 is a cross-sectional view of an electromagnetic wave absorbing floor material according to another embodiment taken along the same line as in FIG. 1 . [Diagram 5] 2 is a cross-sectional view of an electromagnetic wave absorbing floor material according to yet another embodiment taken along the same line as in FIG. 1 . [Figure 6] 2 is a cross-sectional view of an electromagnetic wave absorbing floor material according to yet another embodiment taken along the same line as in FIG. 1 . [Figure 7] 2 is a cross-sectional view of an electromagnetic wave absorbing floor material according to yet another embodiment taken along the same line as in FIG. 1 . [Figure 8] 2 is a cross-sectional view of an electromagnetic wave absorbing floor material according to yet another embodiment taken along the same line as in FIG. 1 . [Figure 9] 2 is a cross-sectional view of an electromagnetic wave absorbing floor material according to yet another embodiment taken along the same line as in FIG. 1 . [Figure 10] 2 is a cross-sectional view of an electromagnetic wave absorbing floor material according to yet another embodiment taken along the same line as in FIG. 1 . [Figure 11] 2 is a cross-sectional view of an electromagnetic wave absorbing floor material according to yet another embodiment taken along the same line as in FIG. 1 . [Figure 12] FIG. [Figure 13] FIG. [Figure 14] FIG. 11 is a plan view of a first reflective layer according to a modified example. [Figure 15] FIG. 11 is a plan view of a first reflective layer according to another modified example. [Figure 16] FIG. [Figure 17] FIG. 1 is a reference perspective view showing an example of a location where an electromagnetic wave absorbing floor material is installed. [Figure 18] A reference plan view showing horizontal and vertical marking lines on the floor surface at the construction site. [Figure 19] A reference plan view showing the state in which multiple electromagnetic wave absorbing flooring materials are laid after the first electromagnetic wave absorbing flooring material is laid. [Figure 20] Graph showing the relationship between the frequency of electromagnetic waves and the reflection coefficient of the electromagnetic wave-absorbing floor material of Example 1. [Figure 21] FIG. 2 is a reference perspective view for explaining a method for testing the caster resistance of the electromagnetic wave absorbing floor material of Example 1. [Figure 22] FIG. 4 is a reference plan view illustrating the method of the caster resistance test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] The present invention will now be described with reference to the accompanying drawings. In this specification, plan view refers to a view from a direction perpendicular to the surface of the electromagnetic wave absorbing flooring material, and plan view shape refers to the shape when viewed from that direction. In this specification, terms may be prefixed with "first," "second," etc., but this "first," etc. is added only to distinguish the terms and does not have any special meaning such as order or superiority. In this specification, when multiple numerical ranges of X (lower limit) or more and Y (upper limit) or less are separately described, it is considered that any lower limit and any upper limit can be selected to set "any lower limit or more and any upper limit or less." It should be noted that the thicknesses of layers and the like shown in each drawing may differ from the actual ones.

[0012] [Outline of electromagnetic wave absorbing flooring] FIG. 1 is a basic plan view of an electromagnetic wave absorbing flooring 1. FIG. 2 is a cross-sectional view of an electromagnetic wave absorbing flooring 1 of one embodiment cut at a location where the reflective film 31 of the first reflective layer 3 exists, and is a cross-sectional view cut along line II-II in FIG. 1 as an example of a location where the reflective film exists. FIG. 3 is a cross-sectional view of an electromagnetic wave absorbing flooring 1 of one embodiment cut at a location where the reflective film 31 of the first reflective layer 3 does not exist, and is a cross-sectional view cut along line III-III in FIG. 1 as an example of a location where the reflective film 31 does not exist. FIGs. 4 to 11 are cross-sectional views of electromagnetic wave absorbing flooring 1 of various other embodiments cut at a location where the reflective film 31 of the first reflective layer 3 exists (cross-sectional views of the same electromagnetic wave absorbing flooring 1 cut at the same location as line II-II in FIG. 1). Plan views of the electromagnetic wave absorbing flooring 1 of other embodiments are omitted because they are the same as FIG. 1.

[0013] 1 to 3, the electromagnetic wave absorbing floor material 1 has, from the front surface side, a front protective layer 2, a first reflective layer 3, a spacing layer 4, a second reflective layer 5, and a rear protective layer 6. Both the surface protective layer 2 and the spacing layer 4 are layers that are electromagnetically transmissible. In other words, neither the surface protective layer 2 nor the spacing layer 4 includes a layer that substantially reflects, absorbs, or blocks electromagnetic waves. The back surface protective layer 6 may be a layer that is permeable to electromagnetic waves, or may be a layer that reflects, absorbs, or blocks electromagnetic waves. The thickness of the electromagnetic wave absorbing floor material 1 is not particularly limited, but is, for example, 2 mm to 15 mm, and preferably 3 mm to 10 mm. If it is within this range, it can be handled in the same way as a general resin floor material, and can be easily transported and installed. The electromagnetic wave absorbing floor material 1 can achieve high durability within the above thickness range, and is unlikely to be damaged or change in dimensions over time, so that it can stably maintain good electromagnetic wave absorbing properties for a long period of time.

[0014] Both the first reflective layer 3 and the second reflective layer 5 have a reflective film that reflects electromagnetic waves. The reflective film of the first reflective layer 3 is made of a plurality of reflective films 31 (herein, these reflective films are referred to as partial reflective films 31) provided at intervals in the surface direction. The reflective film of the second reflective layer 5 is made of one reflective film 51 (herein, this reflective film is referred to as full reflective film 51) provided over the entire surface direction. The planar shape of the electromagnetic wave absorbing flooring 1 is generally a square sheet as shown in FIG. 1, but it can also be changed to a rectangular, triangular, circular, elliptical, or other sheet shape (not shown). The sheet shape is also called a tile shape. The planar shape of the electromagnetic wave absorbing flooring 1 is preferably similar to the partially reflective film 31. For example, if the electromagnetic wave absorbing flooring 1 and the partially reflective film 31 are both square, the partially reflective film 31 can be arranged in the surface direction at uniform intervals in the planar view, and the electromagnetic wave absorbing flooring 1 with excellent electromagnetic wave absorption properties can be configured. The arrangement of the partially reflective film 31 is preferably a structure in which multiple elements are regularly arranged vertically and horizontally in a lattice or checkerboard pattern, that is, a so-called "matrix pattern." The size of the sheet-like electromagnetic wave absorbing floor material 1 is 300 mm or more and 2000 mm or less in length and width, respectively, taking into consideration ease of handling during construction. The electromagnetic wave absorbing flooring material 1 is not limited to a sheet-like shape having a predetermined planar shape such as a square shape as described above, but may be formed in a long strip shape. A long strip shape is also called a sheet shape. A long strip shape refers to a long and narrow rectangular shape in plan view, in which the length in one direction is sufficiently longer than the length in the other direction (the other direction is a direction perpendicular to the one direction in the plane). The electromagnetic wave absorbing flooring material 1 formed in a long strip shape has flexibility that allows it to be wound into a roll, and can be easily stored and transported in the rolled state.

[0015] [About each layer of electromagnetic wave absorbing flooring] <PVC resin layer> The PVC resin layer referred to in this specification is a layer formed from a material containing a vinyl chloride resin and a plasticizer, and optionally contains a filler and / or any suitable additive. In order not to adversely affect the electromagnetic wave absorption characteristics, the PVC resin layer has a dielectric constant of, for example, 3.0 F / m or more and 4.8 F / m or less, preferably 3.3 F / m or more and 4.5 F / m or less. Vinyl chloride resins include polymers formed by polymerizing at least vinyl chloride monomer (chloroethylene). Vinyl chloride resins include not only homopolymers formed by homopolymerizing chloroethylene, but also copolymers of chloroethylene and other monomers that can be copolymerized with chloroethylene, mixtures of homopolymers and copolymers, and mixtures of two or more copolymers. The term "mixture" refers to a homopolymer and copolymer, or a polymer in which copolymers are kneaded together without substantially polymerizing each other. Examples of vinyl chloride resins include vinyl chloride polymers (homopolymers); chlorinated vinyl chloride; partially crosslinked vinyl chloride; copolymers containing vinyl chloride such as vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer, vinyl chloride-styrene copolymer, vinyl chloride-isobutylene copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-butadiene copolymer, vinyl chloride-isoprene copolymer, and vinyl chloride-chlorinated propylene copolymer; mixtures of homopolymers and one or more copolymers, and mixtures of two or more copolymers. Preferably, vinyl chloride polymer (homopolymer) is used. These vinyl chloride resins may be used alone or in combination of two or more. Vinyl chloride resins are used as virgin materials, but recycled materials may be used as necessary, or a mixture of virgin materials and recycled materials may be used.

[0016] The vinyl chloride polymer (homopolymer) may be produced by an emulsion polymerization method, a suspension polymerization method, a solution polymerization method, a bulk polymerization method, or the like, and it is preferable to use a paste vinyl chloride resin and / or a suspension vinyl chloride resin. The vinyl chloride paste resin is, for example, a vinyl chloride paste obtained by emulsion polymerization, and the viscosity can be adjusted appropriately by a plasticizer. The vinyl chloride paste resin is a fine powder consisting of a large number of fine particle aggregates with a particle diameter of 0.1 to 10 μm (preferably 1 to 3 μm), and preferably the surface of the fine powder is coated with a surfactant. The average degree of polymerization of the vinyl chloride paste resin is preferably about 1000 to 2000. The suspension vinyl chloride resin is, for example, a vinyl chloride resin obtained by suspension polymerization. The suspension vinyl chloride resin is a fine powder with a particle size of preferably 20 μm or more and 100 μm or less. The average polymerization degree of the suspension vinyl chloride resin is preferably about 700 or more and 1500 or less, more preferably about 700 or more and 1100 or less, and even more preferably about 700 or more and 1000 or less. The electromagnetic wave absorbing floor material 1 using such a polyvinyl chloride resin can be applied to the floor surface in the same way as other general polyvinyl chloride resin floor materials, and can be maintained in the same way after application, resulting in excellent work efficiency. In addition, since polyvinyl chloride resin has heat resistance, it can suppress deterioration even in high-temperature environments and maintain its electromagnetic wave absorbing properties.

[0017] The plasticizer is mainly blended for the purpose of improving the flexibility of the vinyl chloride resin. Examples of the plasticizer include polyester plasticizers, glycerin plasticizers, polycarboxylic acid ester plasticizers, and polyalkylene glycol plasticizers. Preferably, the plasticizer is a polycarboxylic acid plasticizer, more preferably, a phthalic acid ester, and particularly preferably, dioctyl phthalate. The filler is blended mainly for the purpose of improving the processability and physical properties of the PVC resin layer. The filler may be opaque, transparent, or translucent. Examples of opaque fillers include inorganic fillers such as calcium carbonate, titanium oxide, calcium oxide, barium carbonate, magnesium hydroxide, aluminum hydroxide, clay, talc, and mica. Examples of transparent or translucent fillers include organic fillers such as resin beads, and inorganic fillers such as glass beads. In particular, it is preferable that the filler contains calcium carbonate, since it can impart good dimensional stability and increase the weight of the flooring material. By increasing the weight, the electromagnetic wave absorbing material 1 can be fixed more stably to the floor surface, which also contributes to stabilizing the electromagnetic wave absorption characteristics. As the additives, conventionally known ones can be used, and examples thereof include colorants, flame retardants, stabilizers, antioxidants, lubricants, antibacterial agents, antifungal agents, and surfactants.

[0018] <Surface protective layer> The surface protective layer 2 is provided on the surface side of the first reflective layer 3 and protects the first reflective layer 3. The surface of the surface protective layer 2 constitutes the surface of the electromagnetic wave absorbing floor material 1. The surface protective layer 2 has a PVC resin layer containing a vinyl chloride resin. The thickness of the surface protective layer 2 is not particularly limited, but is, for example, 0.1 mm to 2 mm, preferably 0.2 mm to 1 mm. If it is equal to or greater than the lower limit, the durability of the floor material can be increased, and the partial reflection film 31 can be appropriately protected from impacts caused by wheels or the soles of people's feet. If it is equal to or less than the upper limit, it is possible to suppress the position of the partial reflection film 31 from being shifted due to impact, which adversely affects the electromagnetic wave absorption characteristics. The surface protective layer 2 may have a single-layer structure or a multi-layer structure. When the surface protective layer 2 has a single-layer structure, the surface protective layer 2 is made of the PVC resin layer. When the surface protective layer 2 has a multi-layer structure, at least one of the layers is made of the PVC resin layer. The surface protective layer 2 may contain a microfoamed resin layer, but preferably does not contain a foamed layer. In other words, it is preferable that all layers constituting the surface protective layer 2 are non-foamed layers. If necessary, the surface of the surface protective layer 2 may be embossed, such as with a matte finish (not shown). By embossing with an appropriate shape, it is also possible to improve the abrasion resistance of the surface protective layer 2.

[0019] The surface protective layer 2 in one embodiment has a two-layer structure as shown in Fig. 2 and Fig. 3. For example, the surface protective layer 2 has a first surface layer 21 and a second surface layer 22 in order from the surface side. In another embodiment, the surface protective layer 2 has a three-layer structure as shown in Fig. 4. For example, the surface protective layer 2 has a third surface layer 23, a fourth surface layer 24, and a fifth surface layer 25 in order from the surface side. Although not shown, the surface protective layer 2 may have a structure of four or more layers. Furthermore, the surface protective layer 2 may have at least one PVC resin layer, and preferably has two or more PVC resin layers.

[0020] The first surface layer 21 and the fourth surface layer 24 are, for example, PVC resin layers each containing a vinyl chloride resin. The second surface layer 22 and the fifth surface layer 25 are, for example, PVC resin layers each containing a vinyl chloride resin, but are preferably PVC resin layers with decorative coating. Examples of the PVC resin layers with decorative coating include PVC resin layers with decorative printing on the back and / or front, PVC resin layers containing coloring agents and colored in desired colors, and PVC resin layers with colored chips blended therein. The coating may be unpatterned in one color, or may be patterned, letters, and / or pictures in one or more colors. In addition, the coating is preferably such that the partial reflection film 31 of the first reflection layer 3 described later is concealed so that the shape of the partial reflection film 31 is not revealed on the surface of the electromagnetic wave absorbing flooring 1. The thickness of the PVC resin layers such as the first surface layer 21 and the second surface layer 22 is not particularly limited, but is, for example, 0.05 mm or more and 0.5 mm or less. The third surface layer 23 is, for example, an ionizing radiation curable resin layer such as an ultraviolet curable resin. The thickness of the third surface layer 23 is not particularly limited, but is, for example, 1 μm or more and 150 μm or less. When the second surface layer 22 and the fifth surface layer 25 are made cosmetic, the first surface layer 21, the third surface layer 23 and the fourth surface layer 24 are made transparent or semi-transparent so that the color of the cosmetic can be seen through.

[0021] The PVC resin layer of the first surface layer 21 and the PVC resin layer of the second surface layer 22 may have the same composition or different compositions. The PVC resin layer of the fourth surface layer 24 and the PVC resin layer of the fifth surface layer 25 may have the same composition or different compositions. In other words, when the surface protective layer 2 is made up of a plurality of PVC resin layers, the PVC resin layers may have the same composition or different compositions. Different compositions means that the type of vinyl chloride resin, components other than vinyl chloride resin, content of vinyl chloride resin, and / or content of components other than vinyl chloride resin are different. Each of the PVC resin layers, which are the first surface layer 21, the second surface layer 22, the fourth surface layer 24, and the fifth surface layer 25, independently contains a vinyl chloride resin and a plasticizer, and if necessary, contains an additive. The PVC resin layer constituting the surface protective layer 2 such as the first surface layer 21 may contain a filler, but preferably does not contain a filler. When the surface protective layer 2 has a PVC resin layer that does not contain a filler, the content of the vinyl chloride resin in the PVC resin layer of the surface protective layer 2 becomes relatively high, and the durability of the surface protective layer 2, such as the abrasion resistance, is improved. When such a surface protective layer 2 is provided on the surface side of the spacing layer 4, concentrated load is unlikely to be applied to the spacing layer 4, and it is possible to prevent the thickness of the spacing layer 4 from being partially reduced over time. Generally, localized loads are applied over the long term as wheels or people pass over the flooring material, but the provision of the surface protective layer 2 prevents the first reflective layer 3 and the spacing layer 4 from being scratched, making it difficult for localized damage such as dents to form, and enabling the electromagnetic wave absorption characteristics to be stably maintained. The composition of each PVC resin layer (first surface layer 21, second surface layer 22, etc.) constituting the surface protective layer 2 is appropriately set, and each independently contains, for example, 25 to 55 parts by weight of a plasticizer and 0.1 to 4 parts by weight of an additive relative to 100 parts by weight of the vinyl chloride resin contained in the PVC resin layer. When the PVC resin layer constituting the surface protective layer 2 contains a filler, the amount thereof is, for example, 1 to 50 parts by weight.

[0022] In another embodiment, the surface protective layer 2 has a single-layer structure as shown in Fig. 5. The single-layer surface protective layer 2 is made of a PVC resin layer. This PVC resin layer may or may not be decorated.

[0023] <First Reflective Layer and Second Reflective Layer> The first reflective layer 3 includes a plurality of partial reflective films 31 arranged in a matrix in the surface direction, and the second reflective layer 5 includes a full reflective film 51 arranged over the entire surface in the surface direction. The first reflective layer 3 is laminated on the back surface side of the surface protective layer 2, and the second reflective layer 5 is laminated on the back surface side of the spacing layer 4. The reflective film (partially reflective film 31 and fully reflective film 51) is made of a material capable of reflecting electromagnetic waves, and is typically made of a metal film such as aluminum, copper, or an alloy. In particular, it is preferable to use aluminum in terms of electromagnetic characteristics, workability, and cost. The thickness of the reflective film is not particularly limited, and is 0.001 μm or more and 20 μm or less, and preferably 0.1 μm or more and 5 μm or less. If it is equal to or more than the lower limit, electromagnetic waves can be reflected well, and if it is equal to or less than the upper limit, the flooring material can be prevented from becoming too hard. The first reflective layer 3 and the second reflective layer 5 may each be composed of only the reflective film (metal film, etc.), but are usually composed of a reflective film and a base film supporting the reflective film. The base film is not particularly limited as long as it is a film that can transmit electromagnetic waves, and known resin films such as polyethylene terephthalate film, polyethylene film, and vinyl chloride film can be used. The thickness of the base film is not particularly limited, and is, for example, 5 μm or more and 5000 μm or less, and preferably 10 μm or more and 200 μm or less. If it is equal to or more than the lower limit, sufficient strength can be obtained, and if it is equal to or less than the upper limit, it is not too hard and good processability can be obtained. It is preferable to use a polyethylene terephthalate film as the base film, since it is easy to form a reflective film and has excellent dimensional stability and rigidity.

[0024] As shown in FIG. 12, the first reflective layer 3 has a base film 32 (hereinafter, referred to as the first base film 32 to distinguish it from the base film 52 of the second reflective layer 5) and a partially reflective film 31 provided on one side of the first base film 32. The planar shape of the partially reflective film 31 can be appropriately set on the condition that it can exhibit electromagnetic wave absorption characteristics, and examples of such shapes include polygonal shapes such as a triangle, a square, a hexagon, and an octagon; regular polygonal shapes such as a square, a rectangle, an equilateral triangle, a regular hexagon, and a regular octagon; a circle; and an ellipse. These shapes include substantially the same shapes that achieve the effects of the present invention, that is, shapes within a range that can be replaced. The range that can be replaced for the polygonal shapes includes, for example, shapes with chamfered corners, shapes with a part of a side slightly bulging or recessed, and shapes with slightly curved sides. The range in which the circular shape and the approximately elliptical shape can be substituted includes, for example, a shape in which part of the periphery is slightly bulged or depressed, and a shape in which part of the periphery is slightly straight or oblique.

[0025] The planar shape of the partial reflection film 31 is preferably similar to the planar shape of the electromagnetic wave absorbing flooring 1. The similar shape makes it easy to arrange the partial reflection film 31 in a matrix shape by making the partial reflection film 31 parallel to the edge of the electromagnetic wave absorbing flooring 1, and even after laying a plurality of electromagnetic wave absorbing floorings 1 on the floor surface, the interval between the partial reflection films 31 of adjacent electromagnetic wave absorbing floorings 1 can be set to a constant value, and uniform electromagnetic wave absorption characteristics can be exhibited. For example, as shown in FIG. 13, the partial reflection film 31 is formed in a square or rectangular shape. For example, if the electromagnetic wave absorbing flooring 1 and the partial reflection film 31 are both square shaped, the partial reflection film 31 can be arranged at uniform intervals in plan view, and the electromagnetic wave absorption characteristics become uniform over the entire floor surface, and excellent absorption characteristics are stably exhibited. The length A of one side of the square-shaped partial reflection film 31 is appropriately set according to the frequency of the electromagnetic wave to be absorbed, but from the viewpoint of manufacturing, it is preferably 2 mm or more and 150 mm or less. As described above, the planar shape of the partial reflection film 31 includes the shape of the replaceable range, and also includes shapes with chamfered corners. For example, when the shape of the replaceable range of a square shape is illustrated and explained, it includes a case where the corners of the square are chamfered in an inclined manner as shown in FIG. 14, and a case where the corners of the square are chamfered in an arc as shown in FIG. 15. If the corners of a polygonal shape such as a square are chamfered, it is preferable because it can reduce the concentration of electric charges at the corners. As for the chamfering shape, the inclined shape shown in FIG. 14 makes it easy to form the partial reflection film 31, and the arc shape shown in FIG. 15 can adjust the electromagnetic wave absorption characteristics by further reducing the concentration of electric charges at the corners.

[0026] The multiple partial reflection films 31 are arranged in a matrix at predetermined intervals on the surface of the first base film 32. The partially reflective films 31 adjacent in the horizontal direction are arranged with a gap in the horizontal direction, and the partially reflective films 31 adjacent in the vertical direction are also arranged with a gap in the vertical direction. The gap WY between the adjacent partially reflective films 31 in the horizontal direction (hereinafter referred to as the horizontal width WY of the partially reflective films 31) and the gap WT between the adjacent partially reflective films 31 in the vertical direction (hereinafter referred to as the vertical width WT of the partially reflective films 31) are equal, and therefore the multiple partially reflective films 31 are arranged with constant gaps in the horizontal and vertical directions. The area between adjacent partially reflective films 31 is an area (without a reflective film) through which electromagnetic waves can pass. Research by the inventors has revealed that the frequency of electromagnetic waves that can be absorbed changes depending on the width WY and the length WT. Therefore, there is a correlation between the frequency of electromagnetic waves to be absorbed and the width WY and the length WT, and the width WY and the length WT are set according to the frequency of electromagnetic waves to be absorbed. For example, increasing the width WY and the length WT respectively increases the frequency of electromagnetic waves that can be absorbed, and decreasing the width WY and the length WT respectively decreases the frequency of electromagnetic waves that can be absorbed. The horizontal distance WSY (referred to as the horizontal edge width WSY) between the partially reflective film 31 adjacent to the vertical edge of the first base film 32 (corresponding to the vertical edge of the electromagnetic wave absorbing flooring material 1) and the vertical edge of the first base film 32 is set to 1 / 2 of the horizontal width WY. Similarly, the vertical distance WST (referred to as the vertical edge width WST) between the partially reflective film 31 adjacent to the horizontal edge of the first base film 32 (corresponding to the horizontal edge of the electromagnetic wave absorbing flooring material 1) and the horizontal edge of the first base film 32 is set to 1 / 2 of the vertical width WT. Therefore, the horizontal edge width WSY and the vertical edge width WST are equal.

[0027] The second reflective layer 5 has a base film 52 (hereinafter referred to as the second base film 52) and an overall reflective film 51 provided on the entire one surface of the second base film 52, as shown in FIG.

[0028] 2, the first reflective layer 3 and the second reflective layer 5 are laminated with the partial reflective film 31 and the full reflective film 51 facing each other with the spacing layer 4 interposed therebetween. That is, the first reflective layer 3 is laminated between the surface protective layer 2 and the spacing layer 4 with the first base film 32 facing the front side (the surface protective layer 2 side) and the partial reflective film 31 facing the back side (the spacing layer 4 side). The second reflective layer 5 is laminated between the spacing layer 4 and the back protective layer 6 with the full reflective film 51 facing the front side (the spacing layer 4 side) and the second base film 52 facing the back side (the back protective layer 6 side). 6, the first reflective layer 3 is laminated between the surface protective layer 2 and the spacing layer 4 with the partially reflective film 31 facing the front side (the surface protective layer 2 side) and the first base film 32 facing the back side (the spacing layer 4 side). The second reflective layer 5 is the same as in FIG. 7, the second reflective layer 5 is laminated between the spacing layer 4 and the back surface protective layer 6 with the second base film 52 facing the front side (the spacing layer 4 side) and the entire surface reflective film 51 facing the back surface side (the back surface protective layer 6 side). The first reflective layer 3 is the same as in FIG. Although not specifically shown, the first reflective layer 3 is laminated between the surface protective layer 2 and the spacing layer 4, with the partial reflective film 31 facing the front side (surface protective layer 2 side) and the first base film 32 facing the back side (spacing layer 4 side), and further, the second reflective layer 5 may be laminated between the spacing layer 4 and the back protective layer 6, with the second base film 52 facing the front side (spacing layer 4 side) and the full reflective film 51 facing the back side (back protective layer 6 side). As described below, during manufacturing of the electromagnetic wave absorbing flooring material 1, the material is heated and pressed in the thickness direction, and by placing the partial reflective film 31 and the full reflective film 51 facing each other, the spacing layer 4 is well bonded to the partial reflective film 31 and the full reflective film 51. In addition, when the first base film 32 and the second base film 52 are resin films other than polyvinyl chloride films, it is preferable that an adhesive material such as a primer (not shown) is applied to both sides of the first reflective layer 3 and the second reflective layer 5 to ensure good adhesion with the PVC resin layer of the surface protective layer 2, the PVC resin layer of the spacing layer 4, and the PVC resin layer of the back protective layer 6. The primer agent is not particularly limited, and examples thereof include two-component curing primers such as urethane-based and polyester-based primers; one-component curing primers such as acrylic-based, vinyl chloride-vinyl acetate copolymer-based primers, and mixtures thereof; and the like.

[0029] According to research by the present inventors, it has been found that the amount of electromagnetic wave absorption varies depending on the distance in the thickness direction between the partial reflection film 31 and the full reflection film 51 (hereinafter referred to as the thickness direction distance). Therefore, there is a correlation between the amount of electromagnetic wave absorption and the thickness direction distance, and the thickness direction distance is set according to the amount of electromagnetic wave absorption. For example, when the thickness direction distance is increased, the amount of electromagnetic wave absorption increases, and when the thickness direction distance is decreased, the amount of electromagnetic wave absorption decreases. In one example, the thickness direction distance is, for example, 0.5 mm or more and 5 mm or less, and preferably 2.6 mm or more and 4 mm or less. For example, as shown in Fig. 2, when the partial reflection film 31 and the full reflection film 51 are laminated facing each other, the thickness direction interval T is equal to the thickness of the spacing layer 4. As shown in Fig. 6, when the partial reflection film 31 is laminated toward the front surface side, the thickness direction interval T is equal to the sum of the thickness of the spacing layer 4 and the thickness of the first base film 32. As shown in Fig. 7, when the full reflection film 51 is laminated toward the back surface side, the thickness direction interval T is equal to the sum of the thickness of the spacing layer 4 and the thickness of the second base film 52.

[0030] <Spacing layer> The spacing layer 4 is provided on the back surface side of the first reflective layer 3 between the first reflective layer 3 and the second reflective layer 5, and maintains a distance in the thickness direction between the first reflective layer 3 and the second reflective layer 5. The spacing layer 4 has a PVC resin layer containing a vinyl chloride resin. The PVC resin layer of the spacing layer 4 may or may not be decorated. The spacing layer 4 may have a single layer structure or a multi-layer structure. When the spacing layer 4 has a single layer structure, the spacing layer 4 is made of the PVC resin layer. When the spacing layer 4 has a multi-layer structure, at least one of the layers is made of a PVC resin layer. For example, when the spacing layer 4 is formed to be relatively thick, such as 3.2 mm, it is difficult in terms of production to form it as a single layer. By making the spacing layer 4 have a multi-layer structure, a relatively thick spacing layer 4 can be easily produced. The spacing layer 4 may or may not have a fiber reinforcement layer. When the spacing layer 4 includes a fiber reinforcement layer, the fiber reinforcement layer is preferably interposed in the PVC resin layer constituting the spacing layer 4. The fiber reinforcement layer may be located anywhere in the thickness direction of the spacing layer 4, but is preferably located at a position where the entire electromagnetic wave absorbing flooring material 1 does not warp. The position of the fiber reinforcement layer in the thickness direction is set taking into account the thermal expansion coefficients in the surface direction of the surface protective layer 2, the spacing layer 4, and the back protective layer 6. This prevents the electromagnetic wave absorbing flooring material 1 from warping due to temperature changes and maintains its electromagnetic wave absorption properties. The spacing layer 4 may contain a microfoamed resin layer or may not contain a foamed layer. The microfoaming refers to foaming at an expansion ratio of 1.01 to 1.5 times, preferably 1.3 times or less. If the expansion ratio is low, the properties such as improved flexibility and impact absorption obtained by foaming are reduced, so the purpose of foaming is weakened, and if the expansion ratio is too high, the strength of the resin layer may be reduced. It is preferable that the spacing layer 4 does not contain a foamed layer, in other words, it is preferable that all the resin layers constituting the spacing layer 4 are non-foamed layers.

[0031] In one embodiment, as shown in FIG. 2 and FIG. 3, the spacing layer 4 has a first intermediate layer 41, a second intermediate layer 42, a third intermediate layer 43, a fourth intermediate layer 44, and a fifth intermediate layer 45 in order from the surface side. The first intermediate layer 41, the third intermediate layer 43, and the fifth intermediate layer 45 are, for example, PVC resin layers containing vinyl chloride resin. The second intermediate layer 42 and the fourth intermediate layer 44 are, for example, fiber reinforcement layers. These fiber reinforcement layers are sandwiched between the PVC resin layers on the front and back sides. In the illustrated example, the fiber reinforcement layer is provided in the middle part in the thickness direction of the PVC resin layer. The fiber reinforcement layer is impregnated with the vinyl chloride resin of the PVC resin layer, and inside the fiber reinforcement layer, the resin impregnated from the front side and the resin impregnated from the back side are directly bonded and integrated (same below). This integration allows the PVC resin layer and the fiber reinforcement layer to be firmly bonded to each other, resulting in high durability. In another embodiment, as shown in Fig. 8, the spacing layer 4 has a sixth intermediate layer 46, a seventh intermediate layer 47, and an eighth intermediate layer 48, in order from the surface side. The sixth intermediate layer 46 and the eighth intermediate layer 48 are, for example, PVC resin layers containing vinyl chloride resin. The seventh intermediate layer 47 is, for example, a fiber reinforcement layer, which is sandwiched between the PVC resin layers on the front and back (provided in the middle of the PVC resin layers in the thickness direction). Similarly, the spacing layer 4 in Fig. 10 has a sixth intermediate layer 46, a seventh intermediate layer 47, and an eighth intermediate layer 48, in order from the surface side. 9, the spacing layer 4 includes, in order from the surface side, a ninth intermediate layer 49, a tenth intermediate layer 410, and an eleventh intermediate layer 411. The ninth intermediate layer 49, the tenth intermediate layer 410, and the eleventh intermediate layer 411 are each, for example, a PVC resin layer containing a vinyl chloride resin. In this embodiment, the spacing layer 4 does not include a fiber reinforcement layer.

[0032] The PVC resin layer of the first intermediate layer 41, the PVC resin layer of the third intermediate layer 43, and the PVC resin layer of the fifth intermediate layer 45 may have the same composition or different compositions. The PVC resin layer of the sixth intermediate layer 46 and the PVC resin layer of the eighth intermediate layer 48 may have the same composition or different compositions. The PVC resin layer of the ninth intermediate layer 49, the PVC resin layer of the tenth intermediate layer 410, and the PVC resin layer of the eleventh intermediate layer 411 may have the same composition or different compositions. In other words, when the spacing layer 4 is made up of a plurality of PVC resin layers, the PVC resin layers may have the same composition or different compositions. Each PVC resin layer that is an intermediate layer such as the first intermediate layer 41 or the sixth intermediate layer 46 independently contains a vinyl chloride resin and a plasticizer, and contains additives as necessary. The PVC resin layer that constitutes the spacing layer 4 such as the first intermediate layer 41 may not contain a filler, but preferably contains a filler, and more preferably contains an inorganic filler. By having the spacing layer 4 have a PVC resin layer that contains a filler, the spacing layer 4 becomes relatively hard, and dimensional changes in the spacing layer 4 can be suppressed, and changes in the thickness of the spacing layer 4 when a load is applied from the surface side of the electromagnetic wave absorbing flooring material 1 can be suppressed. The composition of each PVC resin layer (first intermediate layer 41, sixth intermediate layer 46, etc.) constituting the spacing layer 4 is set appropriately, but each independently contains, for example, 25 to 55 parts by weight of plasticizer, 1 to 50 parts by weight of filler, and 0.1 to 4 parts by weight of additive relative to 100 parts by weight of vinyl chloride resin contained in the PVC resin layer.

[0033] Examples of the fiber reinforcement layer include nonwoven fabric and woven fabric. The material of the fiber constituting the nonwoven fabric or woven fabric is not particularly limited, and examples include synthetic resin fibers such as polyester and polyolefin; inorganic fibers such as glass and carbon; and natural fibers. In particular, it is preferable to use glass nonwoven fabric or glass woven fabric containing glass fiber as the fiber reinforcement layer because the dimensional change due to temperature is small. Glass nonwoven fabric or glass woven fabric has the characteristics of glass fiber, that is, high strength and small dimensional change due to temperature, and increases the mechanical strength such as dimensional stability and rigidity of the spacing layer 4, and suppresses dimensional change and warping due to shrinkage or expansion over time caused by temperature change. Among them, it is more preferable to use glass nonwoven fabric because the glass fibers are irregularly entangled and the strength can be increased uniformly. The basis weight of the fiber reinforcement layer is, for example, 10 g / m 2 More than 100g / m 2 Preferably, it is 30 g / m or less. 2 More than 50g / m 2 The thickness of the glass fiber is not particularly limited, and is, for example, from 5 μm to 30 μm in diameter, and preferably from 8 μm to 20 μm in diameter. The length of the glass fiber in the glass nonwoven fabric is not particularly limited, and is, for example, from 10 mm to 30 mm in length. The fiber reinforced layer of the second intermediate layer 42 and the fiber reinforced layer of the fourth intermediate layer 44 may be the same or different. By having the fiber reinforcement layer in the spacing layer 4, the dimensional stability of the spacing layer 4 is improved, and thickness changes in the spacing layer 4 when a load is applied from the surface side of the electromagnetic wave absorbing flooring material 1 can be suppressed. In particular, by having the PVC resin layer constituting the spacing layer 4 contain an inorganic filler such as calcium carbonate and the fiber reinforcement layer constituting the spacing layer 4 contain inorganic fibers such as glass, the dimensional stability of the spacing layer 4 is further improved, and thickness changes over time in the spacing layer 4 can be effectively suppressed. Furthermore, when both the first reflective layer 3 and the second reflective layer 5 contain polyethylene terephthalate films, polyethylene terephthalate films have excellent dimensional stability and rigidity, and therefore, by having the fiber reinforcement layer of the spacing layer 4 sandwiched between the two polyethylene terephthalate films, thickness changes over time in the spacing layer 4 can be effectively suppressed.

[0034] <Back surface protective layer> The back surface protective layer 6 is provided on the back surface side of the second reflective layer 5 to protect the second reflective layer 5. The back surface of the back surface protective layer 6 constitutes the back surface of the electromagnetic wave absorbing flooring material 1. The back surface protective layer 6 has a PVC resin layer containing a vinyl chloride resin. The thickness of the back surface protective layer 6 is not particularly limited, but is, for example, 0.2 mm or more and 2 mm or less, and preferably 0.4 mm or more and 1.5 mm or less. The back surface protective layer 6 may have a single layer structure or a multi-layer structure. When the back surface protective layer 6 has a single layer structure, the back surface protective layer 6 is made of the PVC resin layer. When the back surface protective layer 6 has a multi-layer structure, at least one of the layers is made of the PVC resin layer. In addition, the back surface protective layer 6 may include a microfoamed resin layer, or may not include a foamed layer. The microfoaming refers to foaming at an expansion ratio of 1.01 times or more and 1.5 times or less, preferably 1.3 times or less. If the expansion ratio is low, the properties such as flexibility and impact absorption obtained by foaming are reduced, so the purpose of foaming is weakened, and if the expansion ratio is too high, the strength of the resin layer may be reduced. It is preferable that the back surface protective layer 6 does not include a foamed layer, in other words, it is preferable that all of the resin layers constituting the back surface protective layer 6 are non-foamed layers.

[0035] As shown in Figs. 2 and 3, the back surface protection layer 6 in one embodiment has a one-layer structure, and is made of a PVC resin layer as described above. In another embodiment, the back surface protective layer 6 has a three-layer structure as shown in Fig. 9. For example, the back surface protective layer 6 has, in order from the front surface side, a first back surface layer 61, a second back surface layer 62, and a third back surface layer 63. Similarly, the back surface protective layer 6 shown in Fig. 10 has, in order from the front surface side, a first back surface layer 61, a second back surface layer 62, and a third back surface layer 63. In another embodiment, the back surface protective layer 6 has a two-layer structure as shown in Fig. 11. For example, the back surface protective layer 6 has, in order from the front surface side, a fourth back surface layer 64 and a fifth back surface layer 65. Although not shown, the back surface protective layer 6 may have a structure of four or more layers.

[0036] The first back layer 61 and the third back layer 63 are, for example, PVC resin layers each containing a vinyl chloride resin. The second back layer 62 is, for example, a fiber reinforcement layer. At least one of the fourth back layer 64 and the fifth back layer 65 is a PVC resin layer, and preferably, at least the fourth back layer 64 is a PVC resin layer. When either the fourth back layer 64 or the fifth back layer 65 is not a PVC resin layer, that back layer is made of a resin layer other than a vinyl chloride resin or a fiber reinforcement layer.

[0037] The PVC resin layer of the first back layer 61 and the PVC resin layer of the third back layer 63 may have the same composition or different compositions. In other words, when the back surface protective layer 6 is composed of a plurality of PVC resin layers, the PVC resin layers may have the same composition or different compositions. The PVC resin layers of the back surface protective layer 6 such as the first back surface layer 61 each independently contain a vinyl chloride resin and a plasticizer, and also contain an additive. The PVC resin layers constituting the back surface protective layer 6 may not contain a filler, or may contain a filler. It is preferable that the back surface protective layer 6 contains a filler, since this can suppress dimensional changes. The composition of each PVC resin layer constituting the back surface protective layer 6 is appropriately set, and for example, the PVC resin layer contains 25 to 55 parts by weight of a plasticizer and 0.1 to 4 parts by weight of an additive relative to 100 parts by weight of the vinyl chloride resin contained in the PVC resin layer. When the PVC resin layer constituting the surface protective layer 2 contains a filler, the amount thereof is, for example, 1 to 50 parts by weight.

[0038] When the back surface protective layer 6 has a fiber reinforcement layer (for example, when the second back surface layer 62 or the fifth back surface layer 65 is a fiber reinforcement layer), the fiber reinforcement layer may be one exemplified in the above section on <Spacing layer>. Preferably, the fiber reinforcement layer of the back surface protective layer 6 is a glass nonwoven fabric or a glass woven fabric.

[0039] [Method of manufacturing electromagnetic wave absorbing flooring] The electromagnetic wave absorbing floor material 1 can be manufactured, for example, as follows. Here, a method for manufacturing the electromagnetic wave absorbing floor material 1 having the layer structure shown in Fig. 2 will be briefly described. A PVC resin sheet to be the first surface layer 21, and a PVC resin sheet to be the second surface layer 22 on which a decorative print has been applied are prepared. A first base film with a partial reflective film that will become the first reflective layer 3, and a second base film with a full reflective film that will become the second reflective layer 5 are prepared. The partial reflective film 31 and the full reflective film 51 can be formed by a method such as metal deposition, printing containing metal particles, or transferring a metal deposition film onto a polyethylene terephthalate film. A primer agent is preferably applied to both sides of each of the first base film with a partial reflective film and the second base film with a full reflective film. Also, PVC resin sheets to become the first intermediate layer 41, the third intermediate layer 43, and the fifth intermediate layer 45 are prepared, and fiber reinforcement layers to become the second intermediate layer 42 and the fourth intermediate layer 44 are prepared. Furthermore, a PVC resin sheet to become the back surface protective layer 6 is prepared.

[0040] A laminate is prepared by stacking the following layers in order from the front side: PVC resin sheet / decorated PVC resin sheet / first base film with partial reflection film / PVC resin sheet / fiber reinforcement layer / PVC resin sheet / fiber reinforcement layer / PVC resin sheet / second base film with full reflection film / PVC resin sheet. The laminate is integrated by heating and pressing with a press. The heating temperature is, for example, 130°C or higher and 170°C or lower, and the pressure is, for example, 20 kgf / cm. 2 More than 80kgf / cm 2 After the laminate is integrated, it is possible to obtain a sheet-shaped electromagnetic wave absorbing flooring material 1 as shown in Figures 1 to 3 by cutting it with a punching machine or the like. The accuracy of cutting performed with a punching machine or the like is ±50% or less, preferably ±30% or less, and more preferably ±20% or less. For example, a cutting accuracy of ±50% means that when the horizontal end width WSY and vertical end width WST are designed to be 10 mm, the cutting accuracy is 5 mm to 15 mm. It is also possible to manufacture the electromagnetic wave absorbing flooring material 1 using a long strip of PVC resin sheet or the like. In that case, the long strip of layers is laminated in order, the laminate is heated and pressurized to integrate it, and then cut with a cutter or the like to obtain the long strip of electromagnetic wave absorbing flooring material. The long strip of electromagnetic wave absorbing flooring material is stored in a rolled state.

[0041] [Installation of electromagnetic wave absorbing flooring] The electromagnetic wave absorbing floor material 1 of the present invention is applied to the floor surface of the application site, and it is preferable to apply the floor material so that the center of the electromagnetic wave absorbing floor material 1 is located at the position where the electromagnetic wave intensity is strongest. For example, if the electromagnetic wave is strongest at the center of the floor surface of the application site, the electromagnetic wave absorbing floor material 1 is applied to the application site as follows. In other words, the method of installing electromagnetic wave absorbing flooring comprises the steps of marking horizontal and vertical marking lines that extend in a cross shape when viewed in a plane on the floor surface of the installation site, laying the first electromagnetic wave absorbing flooring to be laid on the floor surface by approximately aligning the centre of gravity of the first electromagnetic wave absorbing flooring with the intersection of the horizontal and vertical marking lines, and laying the next electromagnetic wave absorbing flooring in sequence along the horizontal or vertical edge of the first electromagnetic wave absorbing flooring that has been laid.

[0042] <Construction location> FIG. 17 shows an example of a construction site. In Fig. 17, a walk-through type RFID reader 8 is installed on the floor. An electromagnetic wave absorbing floor material is laid on at least the floor surface 91 on which the RFID reader 8 is installed. In Fig. 17, the floor surface 91 on which the electromagnetic wave absorbing floor material is laid is shaded. Any suitable electromagnetic wave absorber is also attached to the inner wall surfaces and ceiling surface of the RFID reader. The baggage to which the RFID tag is attached is placed on a carrier such as a dolly, and the carrier is passed through a walk-through RFID reader 8. The RFID reader 8 irradiates electromagnetic waves to read the RFID information of the baggage. This makes it possible to streamline receiving and shipping operations.

[0043] <Display process> The display step displays a horizontal marking line extending in the horizontal direction and a vertical marking line extending in the vertical direction and perpendicular to the horizontal marking line on the floor surface. As shown in Fig. 18, the horizontal marking line LY and the vertical marking line LT are both straight lines and perpendicular to each other. In the illustrated example, the horizontal marking line LY and the vertical marking line LT are represented by small dashed lines. The horizontal mark line LY is displayed extending horizontally near approximately the vertical midpoint of the construction site 9, and the vertical mark line LT is similarly displayed extending vertically near approximately the horizontal midpoint of the construction site 9. The intersection B of the horizontal mark line LY and the vertical mark line LT roughly coincides with the center of gravity of the floor surface 91 of the construction site 9 in a plan view. The floor surface 91 of the construction site 9 is, for example, the floor surface on which the walk-through type RFID reader 8 described above is installed, and the intersection B is the position where the intensity of the applied electromagnetic wave is strongest. The horizontal marking lines LY and vertical marking lines LT can be formed independently by drawing straight lines on the floor surface with chalk, India ink, or the like, or by sticking colored tape in a straight line on the floor surface 91, or the like.

[0044] <First process of laying electromagnetic wave absorbing flooring> The first sheet-shaped electromagnetic wave absorbing floor material is laid on the floor surface 91 of the construction site 9. The first electromagnetic wave absorbing floor material 1-1 is laid so that its center of gravity approximately coincides with the intersection B of the horizontal mark line LY and the vertical mark line LT, as shown in Fig. 19. If necessary, an adhesive such as a glue or a pressure sensitive adhesive may be applied to the floor surface 91 before laying the electromagnetic wave absorbing floor material 1. It is preferable to use an adhesive as the adhesive. The electromagnetic wave absorbing floor material 1 can be firmly fixed to the floor surface 91 by the adhesive, so that even if a heavy transport vehicle repeatedly passes over the floor material 1, it is possible to prevent parts of the floor material 1 from floating or shifting out of position. The center of gravity of the electromagnetic wave absorbing floor material 1 is the center of gravity in a planar view. In other words, it means the center of gravity of the shape of the electromagnetic wave absorbing floor material 1 in a planar view.

[0045] <Next, laying process of electromagnetic wave absorbing flooring> After laying the first electromagnetic wave absorbing floor material 1-1, the vertical edge (or horizontal edge) of the second electromagnetic wave absorbing floor material 1-2 is butted up tightly against the vertical edge (or horizontal edge) of the first electromagnetic wave absorbing floor material 1-1, and the second electromagnetic wave absorbing floor material 1-2 is laid on the floor surface, as shown in Fig. 19. After that, the third and subsequent electromagnetic wave absorbing floor materials 1-3 are laid in the same manner, so that the electromagnetic wave absorbing floor material 1 can be laid on the entire floor surface 91 of the construction site 9, and an electromagnetic wave absorbing floor structure can be constructed. It is preferable that the electromagnetic wave absorbing floor structure to be constructed has three or more odd-numbered partial reflection films 31 arranged vertically in a plan view. Similarly, it is preferable that the electromagnetic wave absorbing floor structure to be constructed has three or more odd-numbered partial reflection films 31 arranged horizontally in a plan view. For example, as shown in Fig. 1, when an electromagnetic wave absorbing floor material 1 having five partial reflection films 31 arranged vertically and horizontally is used, an electromagnetic wave absorbing floor structure in which three or more odd-numbered partial reflection films 31 are arranged vertically and horizontally can be constructed by laying the electromagnetic wave absorbing floor material 1 in the vertical and horizontal directions on the floor surface 91 of the construction site 9 without cutting it. The electromagnetic wave absorbing floor material 1 can also be cut and laid, in which case it is cut within the range of the vertical width WT and horizontal width WY where the partially reflective film 31 does not exist, preferably cut at the middle (1 / 2 position) of the vertical width WT and horizontal width WY, and laid taking into consideration the number of partially reflective films 31, thereby constructing an electromagnetic wave absorbing floor structure in which an odd number (3 or more) of partially reflective films 31 are arranged vertically and horizontally. With such an electromagnetic wave absorbing floor structure, the electromagnetic wave absorbing characteristics are less likely to be reduced by the joints of the floor material 1.

[0046] The reflected electromagnetic waves within the space of the construction site 9 are strongest near the center of the construction site 9, so if the joints between adjacent electromagnetic wave absorbing floor materials 1 are located near the center of the construction site 9, the absorption effect of the electromagnetic waves (reflected waves) will decrease. In this regard, the electromagnetic wave absorbing floor structure constructed as described above has the center of gravity of one electromagnetic wave absorbing floor material 1 approximately coincident with the center of gravity of the construction site 9, so it can efficiently absorb the electromagnetic waves reflected at the construction site. As described above, the horizontal end width WSY and vertical end width WST of the electromagnetic wave absorbing floor material 1 are 1 / 2 of the horizontal width WY and vertical width WT, so the sum of the horizontal end widths WSY of two adjacent electromagnetic wave absorbing floor materials 1 with a joint between them is the same as the horizontal width WY, and the sum of the vertical end widths WST of the two electromagnetic wave absorbing floor materials 1 is the same as the vertical width WT. Therefore, when viewed as a whole floor structure, the horizontal widths WY and vertical widths WT of the partially reflective film 31 are all at regular intervals, and electromagnetic waves can be absorbed in approximately equal amounts in the entire surface direction.

[0047] [Effects of electromagnetic wave absorbing flooring] The electromagnetic wave absorbing flooring material 1 can absorb electromagnetic waves of a desired frequency band acting from the surface side. Electromagnetic waves acting on the surface of the electromagnetic wave absorbing flooring material 1 enter the spacing layer 4 between adjacent partial reflection films 31. The electromagnetic waves that enter the spacing layer 4 are reflected by the full-surface reflection film 51 and enter the spacing layer 4, are reflected again by the partial reflection film 31 and enter the spacing layer 4, and are reflected again by the full-surface reflection film 51. As the electromagnetic waves are repeatedly reflected between the full-surface reflection film 51 and the partial reflection film 31, they gradually decay by being converted into thermal energy, etc., and are absorbed.

[0048] In the electromagnetic wave absorbing flooring material 1, the spacing layer 4, the surface protective layer 2, and the back protective layer 6 each have a PVC resin layer containing a vinyl chloride resin, so that even if a wheel or a person passes over the surface and a load is partially applied, the thickness of the spacing layer 4 and the like can be prevented from being partially reduced. In particular, since the PVC resin layer of the surface protective layer 2 does not contain a filler and the PVC resin layer of the spacing layer 4 contains a filler, the thickness of the spacing layer 4 is less likely to change due to load. In addition, since the spacing layer 4 has a fiber reinforcement layer, the thickness of the spacing layer 4 is less likely to change. For this reason, the thickness of the spacing layer 4 is less likely to change over time, and the initially set amount of electromagnetic waves can be absorbed over a long period of time. Furthermore, since the back protective layer 6 is provided on the back side of the second reflective layer 5, even if the floor surface at the construction site is uneven, the electromagnetic wave absorbing flooring material 1 is less likely to ripple by following the unevenness. Therefore, the width WY and length WT of the partial reflection film 31 of the electromagnetic wave absorbing flooring material 1 constructed on the floor surface at the construction site remain the initial settings. In other words, the width WY and length WT of the partial reflection film 31 of the constructed electromagnetic wave absorbing flooring material 1 are maintained as the width WY and length WT of the electromagnetic wave absorbing flooring material 1 before construction. Therefore, electromagnetic waves of the set frequency can be efficiently absorbed. EXAMPLES

[0049] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples.

[0050] [Materials used to form the PVC resin layer] <Vinyl chloride resin> Suspension polyvinyl chloride resin (product name "1000Z" manufactured by Shin-Daiichi PVC Co., Ltd.; average degree of polymerization: 1000). <Filling agent> Calcium carbonate (product name "Escalon 200" manufactured by Sankyo Flour Milling Co., Ltd.). <Plasticizer> DOTP (generic product). <Additives> Ba-based stabilizer (product name "ADEKA STAB AC-704" manufactured by ADEKA Corporation).

[0051] [First reflective layer] A polyethylene terephthalate film with aluminum partially vapor-deposited on one side. A primer agent was applied to both sides of this partially vapor-deposited film, and this film was used as the first reflective layer. The primer agent used was a two-component curing primer whose main component was a urethane resin. Thickness of the aluminum vapor-deposited film: 1 μm or less, thickness of the polyethylene terephthalate film: 20 μm, shape and size of the polyethylene terephthalate film: square with each side being 500 mm. 13, the partially reflective film 31 of this first reflective layer (partially deposited film) was square in plan view, with the length A of one side being 74 mm. The width WY and length WT were both 26 mm, and the width WSY and length WST were both 13 mm.

[0052] [Second reflective layer] A polyethylene terephthalate film with aluminum entirely vapor-deposited on one side. A primer agent was applied to both sides of this fully vapor-deposited aluminum film, and this film was used as the second reflective layer. The primer agent used was a two-liquid curing primer whose main component was a urethane resin. Thickness of the vapor-deposited aluminum film: 1 μm or less. Thickness of the polyethylene terephthalate film: 20 μm. [Fiber reinforcement layer] Glass nonwoven fabric (product name "FAP30" manufactured by Olivest Co., Ltd.). Thickness of glass nonwoven fabric: approx. 0.45 mm.

[0053] [Example 1] 100 parts by weight of the vinyl chloride resin, 31 parts by weight of plasticizer, and 3.6 parts by weight of additives described above in [Materials used to form PVC resin layer] were mixed and calendared using a general-purpose calendar molding machine to produce a transparent PVC resin sheet with a thickness of approximately 0.2 mm and dimensions of 500 mm x 500 mm, which was used as the first surface layer. A PVC resin sheet (manufactured by Toppan Printing Co., Ltd.) with a thickness of about 70 μm and a size of length×width=500 mm×500 mm with a desired decorative print applied to one side was prepared, and this was used as the second surface layer.

[0054] 100 parts by weight of the vinyl chloride resin, 30 parts by weight of plasticizer, 165 parts by weight of filler, and 1.2 parts by weight of additive were mixed and calendar molded using a general-purpose calendar molding machine to produce a PVC resin sheet with a thickness of approximately 1.6 mm and a length x width of 500 mm x 500 mm, which was used as the sixth and eighth intermediate layers. The above-mentioned glass nonwoven fabric [fiber reinforcement layer] was used as the seventh middle layer.

[0055] 100 parts by weight of the vinyl chloride resin, 30 parts by weight of plasticizer, 165 parts by weight of filler, and 1.2 parts by weight of additive were mixed and calendared using a general-purpose calendar molding machine to produce a PVC resin sheet with a thickness of approximately 0.8 mm and dimensions of 500 mm x 500 mm, which was used as the back surface protective layer.

[0056] A laminate was produced by stacking the following layers from the front surface side to the back surface side in order: first surface layer 21 (PVC resin sheet without filler), second surface layer 22 (decorated PVC resin sheet without filler), first reflective layer 3 (partially aluminum-deposited film), sixth intermediate layer 46 (PVC resin sheet with filler), seventh intermediate layer 47 (glass nonwoven fabric), eighth intermediate layer 48 (PVC resin sheet with filler), second reflective layer 5 (all-aluminum-deposited film), and back surface protective layer 6. This laminate was heated and pressed at a temperature of about 140°C and a pressure of about 4 MPa using a hot press machine to produce an electromagnetic wave absorbing flooring material 1 as shown in Figures 1 and 8.

[0057] [Electromagnetic wave absorption test] Four electromagnetic wave absorbing floor materials of Example 1 were prepared, and these four electromagnetic wave absorbing floor materials were laid on a flat floor surface with their edges butted together to construct an overall floor structure measuring 1m x 1m in length x width. Electromagnetic waves of 900 MHz to 1100 MHz were irradiated from the surface side of this floor structure and the reflection was measured. The results are shown in Figure 20. As shown in Fig. 20, a peak of the reflection coefficient was confirmed at about 1005 MHz. The smaller the reflection coefficient, the greater the amount of electromagnetic waves absorbed. If the reflection coefficient is smaller than -10, it can be said that the electromagnetic waves are sufficiently absorbed. From Fig. 20, it can be seen that the electromagnetic wave absorbing floor material 1 produced in Example 1 can sufficiently absorb electromagnetic waves with frequencies of about 980 MHz to 1020 MHz.

[0058] [Durability test] The electromagnetic wave absorbing floor material of Example 1 was subjected to the following two types of caster resistance tests. <First Exam> The primary caster resistance test complies with the caster resistance test method A-2 of JIS A 1454:2022. Specifically, as shown in Fig. 21, a 10 mm thick fiber reinforced cement board was placed on the surface of a metal plate, and the electromagnetic wave absorbing flooring material of Example 1 was fixed on the board using adhesive. A caster with a load of about 2000 N (2000 N = about 204 kgf) applied vertically was moved on the surface of this flooring material. In this case, the load per unit area on the caster contact surface of the electromagnetic wave absorbing flooring material was about 900 N / cm 2 The casters were movable forward, backward, left and right, with a wheel diameter of 110 mm, width of 50 mm and made of iron. From the start of the test, the casters were moved continuously at a speed specified by the JIS, tracing a specified trajectory. The trajectory of the casters was a swivel trajectory with the size shown in Figure 22. After the start of the test, the time until the floor material broke or bulged was measured.

[0059] <Secondary Exam> The second test, the caster resistance test, is an additional proprietary test (not specified in the JIS) conducted when the first test shows a dynamic load resistance of 180 minutes or more, and is conducted using smaller wheels. Specifically, a caster with a wheel diameter of 46 mm, width of 20 mm, and made of iron was prepared, which could move back and forth and left and right. Except for using this caster, the caster was moved in the same manner as in the first test, and the time until damage or swelling occurred in the flooring was measured. In this case, since the caster was changed, the load per unit area on the caster contact surface of the electromagnetic wave absorbing flooring was about 2700 N / cm 2 It is.

[0060] <Results and Evaluation> In the first and second tests, the time until the flooring material broke or swelled was measured and evaluated as follows. S rank: 180 minutes or more for the first test and 30 minutes or more for the second test. A rank: 180 minutes or more for the first test and less than 30 minutes for the second test. Rank B: First test takes more than 60 minutes but less than 180 minutes. C rank: Less than 60 minutes in the first test. In the first test, the electromagnetic wave absorbing floor material of Example 1 showed no damage or swelling for 180 minutes or more after the casters started to move. In the second test, no damage or swelling was observed for 30 minutes or more after the casters started to move. This result corresponds to an S rank, which is the best rating for durability in the caster resistance test for flooring materials. Therefore, it is clear that the electromagnetic wave absorbing flooring material of the present invention has excellent durability after being laid on the floor surface, and can maintain its electromagnetic wave absorbing properties for a long period of time. [Explanation of symbols]

[0061] 1. Electromagnetic wave absorbing flooring 2 Surface protective layer 3 1st reflective layer 31 Partially reflective film 4 Spacing layer 5 Second reflective layer 51 Full reflective coating 6 Back protective layer

Claims

1. A surface protective layer; a first reflective layer that is laminated on the back side of the surface protective layer and includes a plurality of partially reflective films that are reflective films that reflect electromagnetic waves and are provided at intervals in a surface direction; A spacing layer laminated on a rear surface side of the first reflective layer; A second reflective layer is laminated on the back surface side of the spacer layer and includes a reflective film that reflects electromagnetic waves and is provided over the entire surface direction; a back surface protection layer laminated on the back surface side of the second reflective layer, An electromagnetic wave absorbing flooring material, wherein the spacing layer, the surface protective layer and the back protective layer each have a PVC resin layer containing a vinyl chloride resin.

2. 2. The electromagnetic wave absorbing floor material according to claim 1, wherein the spacing layer comprises the PVC resin layer and a fiber reinforcement layer interposed in the PVC resin layer.

3. The PVC resin layer of the spacing layer contains the PVC resin and a filler, 3. The electromagnetic wave absorbing flooring material according to claim 1, wherein the PVC resin layer of the surface protective layer contains the PVC resin but does not contain a filler.

4. The PVC resin layer of the spacing layer contains the PVC resin and a filler, 3. The electromagnetic wave absorbing floor material according to claim 1, wherein the PVC resin layer of the surface protective layer contains the PVC resin and a filler.

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