Decorative sheet, decorative member, sensor system, and method for manufacturing decorative sheet

Abstract

To provide a decorative member which allows radio wave transmission at low cost.SOLUTION: A decorative sheet 20 includes a base material 21, and a design layer 23 and a light-shielding layer 25 that are superposed on the base material 21. An opening 24 for transmitting radio waves is formed in the design layer 23. The design layer 23 contains metal flakes.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a decorative sheet, a decorative member having a decorative sheet, a sensor system having a decorative member, and a method for manufacturing a decorative sheet. [Background technology]

[0002] Sensors for observing the external conditions, such as radars mounted on moving objects, are widely used. Sensors function by receiving radio waves from the outside. For example, a collision prevention system mounted on an automobile can predict a collision between an external obstacle and the automobile by emitting radio waves (millimeter waves) to the outside and receiving the radio waves reflected from the outside with a radar, and can automatically take safety measures to prevent the collision.

[0003] A decorative member for improving the design is arranged on the moving body facing the sensor. The decorative member makes the sensor invisible from the outside. The decorative member functions, for example, as an emblem for an automobile. The decorative member as an emblem has an excellent appearance. In order not to interfere with the function of the sensor, the decorative member is configured to be permeable to radio waves. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-189099 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventional decorative members include a vapor-deposited film of a metal such as indium. It is costly to manufacture a decorative member by vapor-depositing a metal. An object of the present disclosure is to provide a decorative member that is transparent to radio waves at low cost. [Means for solving the problem]

[0006] The decorative sheet of the present disclosure is A substrate; A design layer and a light-shielding layer are laminated on the base material, The design layer has an opening for transmitting radio waves formed therein, The design layer includes metal flakes. Effect of the Invention

[0007] According to the present disclosure, a decorative member that transmits radio waves can be provided at low cost. [Brief description of the drawings]

[0008] [Figure 1] Fig. 1 is a diagram for explaining an embodiment of the present invention, and is a perspective view showing a schematic diagram of a moving object equipped with a sensor system. Fig. 1 shows a schematic diagram of an automobile equipped with an emblem as a decorative member arranged facing a sensor as an example of the moving object. [Diagram 2] FIG. 2 is a cross-sectional view of the decorative member and the decorative sheet. [Diagram 3] FIG. 3 is a first example of an enlarged front view of a part of the decorative sheet. [Figure 4] FIG. 4 is a second example of an enlarged front view of a portion of the decorative sheet. [Diagram 5] FIG. 5 is a third example of an enlarged front view of a part of the decorative sheet. [Figure 6] FIG. 6 is a fourth example of an enlarged front view of a part of the decorative sheet. [Figure 7] FIG. 7 is a diagram for explaining an example of a method for producing a decorative sheet. [Figure 8] FIG. 8 is a cross-sectional view of a modified example of the decorative member and the decorative sheet. [Figure 9] FIG. 9 is a diagram for explaining a modified example of the manufacturing method of the decorative member. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] In the drawings attached to this specification, the scale and the aspect ratios have been appropriately changed and exaggerated from those of the actual objects for the convenience of illustration and understanding. Configurations shown in some drawings may be omitted in other drawings.

[0010] In this specification, terms specifying shapes or geometric conditions and their degrees, such as "parallel," "orthogonal," and "same," as well as values ​​of lengths and angles, are not limited to their strict meanings, but are interpreted to include a range within which similar functions can be expected.

[0011] In this specification, terms such as "sheet," "film," and "plate" are not distinguished from one another solely on the basis of differences in name. For example, a "decorative sheet" cannot be distinguished from a member called a "decorative film" or a "decorative plate" solely on the basis of differences in name.

[0012] In this specification, the normal direction of a sheet-like member refers to the normal direction to the sheet surface of the target sheet-like member. Also, the "sheet surface" refers to the surface that coincides with the target sheet-like member when the target sheet-like member is viewed overall and in a global perspective. The same applies when "sheet" is read as "film" or "plate", etc.

[0013] In this specification, when multiple upper limit candidates and multiple lower limit candidates are listed for a parameter, the parameter may be a numerical range that combines any one of the upper limit candidates and any one of the lower limit candidates.

[0014] One embodiment of the present disclosure and its modified examples relate to the following [1] to

[12] . [1] A substrate; A design layer and a light-shielding layer are laminated on the base material, The design layer has an opening for transmitting radio waves formed therein, The decorative sheet, wherein the design layer contains metal flakes. [2] The decorative sheet according to [1], which has a total light transmittance of 5% or less. [3] The decorative sheet according to [1] or [2], which has a visible light transmittance of 5% or less. [4] The decorative sheet according to any one of [1] to [3], wherein the thickness of the design layer is 1 μm or more and 40 μm or less. [5] The decorative sheet according to any one of [1] to [4], wherein the maximum length of the metal flakes is 1 μm or more and 50 μm or less. [6] The design layer contains a binder resin containing the metal flakes, The decorative sheet according to any one of [1] to [5], wherein the content of the binder resin in the design layer is 50% by mass or more and 95% by mass or less. [7] The surface resistivity of the design layer is 1.0×10 5 The decorative sheet according to any one of [1] to [6], having a resistivity of Ω / □ or more. [8] The light-shielding layer is made of a non-conductive material, The decorative sheet according to any one of [1] to [7], wherein the light-shielding layer covers the radio wave transmitting opening. [9] The light-shielding layer is made of a conductive material, The decorative sheet according to any one of [1] to [7], wherein the light-shielding layer is provided with a second radio wave transmitting opening that overlaps with the radio wave transmitting opening.

[10] A molding portion; A design layer and a light-shielding layer are provided on the molding portion, The design layer has an opening for transmitting radio waves formed therein, The decorative member, wherein the design layer includes metal flakes.

[11] A sensor; A sensor system comprising: a decorative member according to

[10] arranged facing the sensor.

[12] A step of overlaying a design film and a light-shielding film on a substrate; A step of irradiating the decorative film with a laser to remove a portion of the decorative film to form an opening for transmitting radio waves, A method for producing a decorative sheet, wherein the decorative film contains metal flakes.

[0015] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 shows a moving body 1 according to an embodiment of the present disclosure. The moving body 1 is a movable device or equipment. In the example shown in FIG. 1, the moving body 1 is an automobile. The moving body 1 may be a motorcycle, a bicycle, a tricycle, a train, an airplane, a ship, a snowmobile, an industrial robot, a drone, or the like. The automobile may be a truck, a bus, a taxi, an ambulance, a fire engine, a police vehicle, a construction vehicle, or the like.

[0016] An automobile as an example of a moving body 1 shown in FIG. 1 includes a sensor system 3. The sensor system 3 includes a sensor 7 and a decorative member 10. The decorative member 10 is disposed facing the sensor 7. The decorative member 10 protects the sensor 7 from the outside. The decorative member 10 makes the sensor 7 difficult to see from the outside. The decorative member 10 imparts a design to the moving body 1. In the example shown in FIG. 1, the decorative member 10 is an emblem 5 that imparts a design to the moving body 1. The sensor 7 may be a radar of a collision prevention system. The decorative member 10 is a small member having a size similar to that of an emblem 5 of an automobile, and may be, for example, a rectangular plate-shaped member having a side length of 50 mm or more and 250 mm or less in a plan view. The decorative member 10 may be a member other than the emblem 5. The decorative member 10 may be, for example, a part of an exterior member such as a roof, a bonnet, a fender, a bumper, a mirror, a door, a pillar, a sill, and a trunk lid. The moving object 1 may have a number of sensor systems 3 .

[0017] The decorative member 10 may include a flat portion or a curved portion on its surface. Fig. 2 shows a cross-sectional view of the decorative member 10. In Fig. 2, the decorative member 10 is shown as a flat surface as a whole for ease of understanding.

[0018] 2, the decorative member 10 includes a first surface 10A and a second surface 10B. The first surface 10A and the second surface 10B are a pair of main surfaces of the decorative member 10. The first surface 10A of the decorative member 10 faces the sensor 7. The decorative member 10 includes a molded portion 11 and a decorative sheet 20, in this order, from the first surface 10A toward the second surface 10B.

[0019] The molded portion 11 is a main body of an exterior member. The molded portion 11 is decorated by a decorative sheet 20. The molded portion 11 has a shape of at least a part of the exterior member of the moving body 1. In the example shown in FIG. 1, the molded portion 11 has a shape of an emblem of an automobile. The molded portion 11 may be produced, for example, by molding a thermoplastic material. The molded portion 11 can be formed into a desired shape by molding. The material of the molded portion 11 may be, for example, glass or resin. The resin may be, for example, an acrylic resin, a polycarbonate resin, an acrylonitrile-butadiene-styrene copolymer, a polycarbonate resin, a polypropylene resin, or a fiber-reinforced plastic.

[0020] When the molded portion 11 is provided on the decorative sheet 20 by insert molding (also called film insert molding) or in-mold molding, the material of the molded portion 11 may be, for example, resin. When the molded portion 11 is provided on the decorative sheet 20 by TOM (Three dimension Overlay Method) molding, the material of the molded portion 11 may be, for example, glass or resin. When the molded portion 11 is provided on the decorative sheet 20 by being bonded with a bonding layer (not shown), the material of the molded portion 11 may be, for example, glass or resin.

[0021] The decorative sheet 20 displays a design. The decorative sheet 20 displays a metallic design. The design displayed by the decorative sheet 20 is L * a * b * L in color space *may be 50 or more, or 60 or more. The decorative member 10 including the decorative sheet 20 displays a design on the second surface 10B. The mobile body 1 including the decorative member 10 exhibits an excellent appearance. The mobile body 1 such as an automobile including the decorative sheet 20 may display a painted metallic or non-metallic (also called solid painted) design.

[0022] L * a * b * L in color space * The value of can be measured as follows using a spectrophotometer (Konica Minolta "CM-700d") with a measurement diameter of Φ8 mm and a viewing angle of 10 degrees. * A black plate with a value of 29.9 is placed on the surface opposite to the surface on which the black plate is placed. Light from a D65 light source is irradiated on the surface opposite to the surface on which the black plate is placed. The L value of the material is calculated from the total reflection light on the material to be measured. * The value of is measured.

[0023] The decorative sheet 20 transmits radio waves, particularly millimeter waves, transmitted and / or received by the sensor 7 with low attenuation. The decorative sheet 20 may have a transmittance of 70% or more, 75% or more, or 80% or more for millimeter waves of 67.5 GHz. The attenuation of the decorative sheet 20 for millimeter waves of 67.5 GHz may be 3.2 dB (decibels) or less, 2.6 dB or less, or 2.0 dB or less.

[0024] The transmittance and attenuation of radio waves are measured by the free space method as follows. In the atmosphere at room temperature, a radio wave transmitter and receiver are placed facing each other. A decorative sheet is placed between the transmitter and receiver so that the normal direction of the sheet surface coincides with the radio wave transmission direction of the transmitter and the radio wave reception direction of the receiver. Radio waves of 67.5 GHz are transmitted from the transmitter and received by the receiver after passing through the decorative sheet. A PNA microwave network analyzer N5227A (manufactured by Keysight Technologies) is used as the radio wave transmitter and receiver. The transmittance and attenuation of radio waves are measured by comparing the radio waves transmitted from the transmitter and the radio waves received by the receiver.

[0025] The following describes how the decorative sheet 20 allows radio waves to pass through with low attenuation while displaying the above-mentioned excellent design.

[0026] As shown in FIG. 2, the decorative sheet 20 includes a base material 21, a design layer 23, a light-shielding layer 25, and a surface layer 27. The design layer 23 and the light-shielding layer 25 are superimposed on the base material 21. In the decorative sheet 20 shown in FIG. 2, the light-shielding layer 25 is located between the base material 21 and the design layer 23. The light-shielding layer 25 is located closer to the first surface 10A of the decorative member 10 than the design layer 23. The design layer 23 has an opening 24 for transmitting radio waves. The opening 24 for transmitting radio waves is a non-formed portion of the design layer 23. The surface layer 27 forms the surface of the decorative sheet 20 and the decorative member 10. The surface layer 27 forms the second surface 10B of the decorative member 10. In FIG. 2, the cross-sectional shape of the design layer 23 is rectangular, but it may be any shape.

[0027] The substrate 21 supports the design layer 23 and the light-shielding layer 25. The substrate 21 is in the form of a film. The substrate 21 may be colored. The substrate 21 may function as the light-shielding layer 25. The substrate 21 may be integrated with the light-shielding layer 25. The substrate 21 may be composed of a plurality of layers. The material of the substrate 21 may be, for example, acrylic, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polystyrene, cyclic polyolefin, or acrylonitrile-butadiene-styrene copolymer. The thickness of the substrate 21 may be 50 μm or more, or 75 μm or more. The thickness of the substrate 21 may be 250 μm or less, or 150 μm or less.

[0028] The design layer 23 forms the design displayed by the decorative sheet 20. The design layer 23 includes a binder resin and metal flakes. The binder resin contains the metal flakes. The design layer 23 forms the design with the metal flakes. The design layer 23 may absorb laser, especially infrared light, so that the portion irradiated with the laser is removed in the manufacturing process of the decorative sheet 20 described below.

[0029] The binder resin encapsulates the metal flakes and stably holds the metal flakes. The content of the binder resin in the design layer 23 may be 50% by mass or more, or 60% by mass or more. The content of the binder resin in the design layer 23 may be 95% by mass or less, or 90% by mass or less. The binder resin may be, for example, a urethane resin, an acrylic polyol resin, an acrylic resin, an ester resin, an amide resin, a butyral resin, a styrene resin, a urethane-acrylic copolymer, a vinyl chloride-vinyl acetate copolymer resin, a vinyl chloride-vinyl acetate-acrylic copolymer resin, a chlorinated propylene resin, a nitrocellulose resin, or a cellulose acetate resin.

[0030] The metal flakes reflect light. The metal flakes may be, for example, aluminum or chromium. The metal flakes are oriented, for example, in a direction along the surface on which the decorative layer 23 is formed. The maximum length of the metal flakes may be 1 μm or more, or 5 μm or more. The maximum length of the metal flakes may be 50 μm or less, or 40 μm or less.

[0031] The maximum length of the metal flakes means the maximum length of the metal flakes measured in all directions when observed from the normal direction of the sheet surface of the decorative sheet 20. The maximum length of the metal flakes is determined from images obtained by a transmission electron microscope (TEM) or a scanning transmission electron microscope (STEM).

[0032] The thickness of the design layer 23 may be 1 μm or more, or 5 μm or more. The thickness of the design layer 23 may be 40 μm or less, 30 μm or less, or 20 μm or less.

[0033] The radio wave transmitting opening 24 is provided to allow radio waves to pass through the design layer 23. The radio wave transmitting opening 24 can increase the surface resistivity of the design layer 23. Specifically, the surface resistivity of the design layer 23 is 1.0×10 5It may be Ω / □ or more, or 1.0×10 6 It may be Ω / □ or more. By increasing the surface resistivity of the design layer 23, the electrical conductivity of the design layer decreases, making it difficult for radio waves to be absorbed by the design layer 23. Radio waves become more easily transmitted through the design layer 23. The radio wave transmitting opening 24 is provided in the design layer 23 only to the extent that it hardly transmits visible light.

[0034] The surface resistivity of the design layer 23 is measured using a resistivity meter (Hiresta UP MCP-HT450 manufactured by Mitsubishi Chemical (now Nitto Seiko Analytech)) in accordance with a method conforming to JIS K6911-1995. A URS probe is used for the measurement. The applied voltage is 10 V. However, if the surface resistivity is high and it is difficult to measure appropriately, the applied voltage is increased appropriately.

[0035] Examples of the shape of the radio wave transmitting opening 24 are shown in Fig. 3 to Fig. 6. Each of the illustrated examples of the radio wave transmitting opening 24 will be described. The radio wave transmitting opening 24 is not limited to the illustrated examples, and may have any shape and arrangement.

[0036] In the example shown in Fig. 3, a plurality of radio wave transmitting openings 24 are provided. The plurality of radio wave transmitting openings 24 are separated from each other. The plurality of radio wave transmitting openings 24 are provided at lattice points of a square lattice. The radio wave transmitting openings 24 are circular. The diameter of the radio wave transmitting openings 24 may be 40 µm or more, or 400 µm or less. The shape of the radio wave transmitting openings 24 is not limited to a circle, and may be an approximately circular shape, an approximately elliptical shape, a square shape, a rectangular shape, a parallelogram shape, an approximately rectangular shape, a cross shape, or the like.

[0037] In the example shown in FIG. 4, a plurality of radio wave transmitting openings 24 are provided. The plurality of radio wave transmitting openings 24 are separated from each other. The plurality of radio wave transmitting openings 24 extend in parallel to each other in a linear manner. The design layer 23 is divided into a plurality of parts by the radio wave transmitting openings 24. The divided design layer 23 extends in parallel to each other in a linear manner. The divided design layer 23 is electrically independent from each other. The surface resistivity of the entire design layer 23 is high. The line width of the radio wave transmitting opening 24 may be 10 μm or more, or may be 40 μm or more. The line width of the radio wave transmitting opening 24 may be 400 μm or less, or may be 250 μm or less. The width of each part of the divided design layer 23 may be 20 μm or more, or may be 500 μm or less.

[0038] In the example shown in FIG. 5, the radio wave transmitting openings 24 are connected as a whole. The radio wave transmitting openings 24 are provided in the form of lines extending in a lattice pattern. The design layer 23 is divided into a plurality of parts by the radio wave transmitting openings 24. The divided design layer 23 is a parallelogram, a rhombus, and particularly a square. The divided design layer 23 is electrically independent from each other. The surface resistivity of the entire design layer 23 is high. The line width of the radio wave transmitting openings 24 may be 10 μm or more, or may be 40 μm or more. The line width of the radio wave transmitting openings 24 may be 400 μm or less, or may be 250 μm or less. The width of each part of the divided design layer 23 may be 20 μm or more, or may be 500 μm or less.

[0039] In the example shown in FIG. 6, the radio wave transmitting opening 24 is connected as a whole. The design layer 23 is divided into a plurality of parts by the radio wave transmitting opening 24. The divided design layer 23 is circular. The divided design layer 23 is electrically independent from each other. The surface resistivity of the entire design layer 23 is high. The minimum length between the two design layers 23 may be 10 μm or more, or 40 μm or more. The minimum length between the two design layers 23 may be 400 μm or less, or 250 μm or less. The diameter of each part of the divided design layer 23 may be 20 μm or more, or 500 μm or less. The shape of the design layer 23 is not limited to a circle, and may be a shape such as a substantially circle or a substantially ellipse.

[0040] The light-shielding layer 25 makes the sensor 7 difficult to see through the decorative member 10 having the decorative sheet 20. The light-shielding layer 25 covers the radio wave transmitting opening 24. The light-shielding layer 25 makes the sensor 7 difficult to see through the radio wave transmitting opening 24. The light-shielding layer 25 absorbs light, particularly visible light. The light-shielding layer 25 does not need to absorb infrared light. The thickness of the light-shielding layer 25 may be 2 μm or more, or 3 μm or more. The thickness of the light-shielding layer 25 may be 20 μm or less, or 15 μm or less.

[0041] The light-shielding layer 25 is made of a non-conductive material. The light-shielding layer 25 is white, yellow, blue, or black. The light-shielding layer 25 contains a binder resin and a colorant contained in the binder resin. The colorant may be, for example, an organic pigment, mica, or titanium dioxide. When the colorant is carbon black or the like and has conductivity, the content of the colorant in the light-shielding layer 25 may be 1 / 3 or less, or 1 / 4 or less, of the content of the binder resin.

[0042] The binder resin may be, for example, a chlorine-based resin, an acrylic resin, a polyurethane, a polyester, a polyamide, a butyral resin, a polystyrene, a nitrocellulose resin, a cellulose acetate resin, etc., and is preferably a chlorine-based resin or an acrylic resin. These binder resins may be used alone or in combination of two or more kinds.

[0043] The surface layer 27 forms the surface of the decorative sheet 20. The surface layer 27 protects the base material 21, the design layer 23, and the light-shielding layer 25. The surface layer 27 has various functions, such as abrasion resistance, weather resistance, and chemical resistance. The surface layer 27 has, for example, abrasion resistance, weather resistance, and chemical resistance required for exterior parts of automobiles, etc., and ductility required for molding.

[0044] The surface layer 27 covers the design layer 23 and the light-shielding layer 25. The surface layer 27 is in contact with the light-shielding layer 25 via the radio wave transmitting opening 24. The surface layer 27 is transparent. The surface layer 27 transmits radio waves transmitted and / or received by the sensor 7. The thickness of the surface layer 27 may be 1 μm or more, or may be 2 μm or more. The thickness of the surface layer 27 may be 20 μm or less, or may be 10 μm or less.

[0045] In this specification, transparent means that the visible light transmittance is 40% or more, 70% or more, or 80% or more. In this specification, the visible light transmittance is specified as the average value of the light transmittance at each wavelength when measured at 1 nm intervals in the range of measurement wavelengths from 380 nm to 780 nm using a spectrophotometer (Shimadzu Corporation's "UV-3600i Plus", compliant with JIS K0115). The incident angle when measuring the visible light transmittance is set to 0° when the transmission direction is not particularly specified. The incident angle is the angle that the traveling direction of the incident light makes with the normal direction to the incident surface, and is a value less than 90°.

[0046] The material of the surface layer 27 may be, for example, a cured product of a polyester resin, an epoxy resin, a polyurethane resin, an aminoalkyd resin, a melamine resin, a guanamine resin, a urea resin, a thermosetting acrylic resin, an ionizing radiation curable resin, etc. From the viewpoint of weather resistance and scratch resistance, it is preferable to use a cured product of an ionizing radiation curable resin as the material of the surface layer 27.

[0047] The ionizing radiation curable resin is a curable resin that is cured by irradiation with ionizing radiation. Ionizing radiation is electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules. The ionizing radiation may be, for example, ultraviolet rays (UV), electron beams (EB), X-rays, gamma rays, or other electromagnetic waves, or alpha rays, ion beams, or other charged particle beams.

[0048] The ionizing radiation curable resin may be any one of a polymerizable monomer, a polymerizable oligomer (prepolymer), and a polymerizable polymer.

[0049] The polymerizable monomer is preferably a (meth)acrylate monomer having a radically polymerizable unsaturated group in the molecule, and among them, a polyfunctional (meth)acrylate monomer is preferable. The polyfunctional (meth)acrylate monomer preferably has two or more polymerizable unsaturated bonds (two or more functional) in the molecule. Specific examples of the polyfunctional (meth)acrylate include ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, isocyanurate di(meth)acrylate, trimethylolpropane di(meth)acrylate, and the like. tri(meth)acrylate, ethylene oxide modified trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, propionic acid modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide modified dipentaerythritol hexa(meth)acrylate, caprolactone modified dipentaerythritol hexa(meth)acrylate, etc. These monomers may be used alone or in combination of two or more.

[0050] The polymerizable oligomer is preferably an oligomer having a radical polymerizable unsaturated group in the molecule, such as an epoxy (meth)acrylate-based, urethane (meth)acrylate-based, polyether-based urethane (meth)acrylate, caprolactone-based urethane (meth)acrylate, polyester (meth)acrylate-based, or polyether (meth)acrylate-based oligomer, and more preferably an urethane (meth)acrylate-based oligomer. The above (meth)acrylate means acrylate or methacrylate. These oligomers may be used alone or in combination of two or more kinds.

[0051] The polymerizable polymer is preferably a polymer having a radically polymerizable unsaturated group in the molecule, such as an epoxy (meth)acrylate-based, urethane (meth)acrylate-based, polyether-based urethane (meth)acrylate, polycaprolactone-based urethane (meth)acrylate, polyester (meth)acrylate-based, or polyether (meth)acrylate-based polymer, and more preferably a polycaprolactone-based urethane (meth)acrylate or urethane (meth)acrylate-based polymer. These polymers may be used alone or in combination of two or more kinds.

[0052] In order to ensure moldability after curing, it is preferable that the polymerizable monomer, polymerizable oligomer (prepolymer), and polymerizable polymer are a mixture of a bifunctional resin and a trifunctional or higher functional resin. The ratio of the bifunctional resin to the trifunctional or higher functional resin (bifunctional resin / trifunctional or higher functional resin) is preferably 5 / 5 or more and 9 / 1 or less. If there is too much trifunctional or higher functional resin, the crosslink density increases, and there is a possibility that the elongation during molding is poor. If there is too much bifunctional resin, there is a possibility that the crosslink density decreases, and sufficient hardness cannot be obtained.

[0053] The surface layer 27 may contain a weather resistance improver. The weather resistance improver may be, for example, an ultraviolet absorber, an antioxidant, and a hindered amine-based light stabilizer.

[0054] The radio wave transmitting openings 24 are provided in the design layer 23 to the extent that they barely transmit visible light, and the light-shielding layer 25 covers the radio wave transmitting openings 24, thereby reducing the total light transmittance, visible light transmittance, and optical density of the decorative sheet 20. Specifically, the total light transmittance of the decorative sheet 20 is 5%. The visible light transmittance of the decorative sheet 20 is 5% or less. The optical density of the decorative sheet 20 is 1.3 or more. Due to the reduced total light transmittance, visible light transmittance, and optical density of the decorative sheet 20, in the sensor system 3, the sensor 7 is less likely to be seen from the outside through the decorative member 10 having the decorative sheet 20.

[0055] Total light transmittance is the ratio of the amount of light that passes through an object to the amount of light that enters the object. Total light transmittance is measured using a haze meter, HM-150, manufactured by Murakami Color Research Laboratory, which complies with JIS K 7361-1.

[0056] Optical density is the degree of absorption of light in a specific wavelength range. Optical density is measured using a transmission densitometer (GretagMacbeth D200-II measuring tube "V(λ)"). The measuring tube "V(λ)" chosen has a central maximum wavelength range of 555 nm.

[0057] An example of a manufacturing method for the decorative sheet 20 and a manufacturing method for the decorative member 10 of this embodiment will be described. The manufacturing method for the decorative sheet 20 includes a step of providing a decorative film 23a and a light-shielding film 25a on a base material 21, a step of providing an opening 24 for transmitting radio waves, and a step of providing a surface layer 27. The manufacturing method for the decorative member 10 includes a step of molding the decorative sheet 20, and a step of forming a molded portion 11 in the decorative sheet 20.

[0058] A design film 23a which will become the design layer 23 and a light-shielding film 25a which will become the light-shielding layer 25 are overlaid on the substrate 21. The design film 23a and the light-shielding film 25a are provided by, for example, printing. The design film and the light-shielding film are provided by any printing method, such as screen printing, offset printing, inkjet printing, and gravure printing. The design film includes a binder resin and metal flakes encapsulated in the binder resin. The light-shielding film includes a binder resin and a colorant encapsulated in the binder resin. Since the thickness of the design film 23a is sufficiently thin and the maximum length of the metal flakes is sufficiently small, the metal flakes are oriented along the surface on which the design film 23a is formed. By forming the design film 23a by printing, it is easier to align the metal flakes in a direction along the main surface compared to painting.

[0059] As shown in Fig. 7, a laser L7 is irradiated onto a portion of the design film 23a. The laser has a wavelength of, for example, 1064 nm infrared light. The laser is irradiated onto the design film 23a at a position where the radio wave transmitting opening 24 is to be formed in the design layer 23 of the decorative sheet 20 to be manufactured. The portion of the design film 23a at the position where the laser was irradiated is removed to form the radio wave transmitting opening 24. The size of the radio wave transmitting opening 24 can be adjusted by adjusting the diameter of the laser irradiated onto the design film 23a. The portion of the design film 23a not irradiated with the laser becomes the design layer 23.

[0060] The design layer 23 and the light-shielding layer 25 may be formed on the substrate 21 by photolithography. The design layer 23 with the radio wave transmission opening 24 formed therein may be provided on the substrate 21 by printing, photolithography, blasting, or the like. The radio wave transmission opening 24 is formed in the design layer 23 without irradiating a laser. When the radio wave transmission opening 24 is connected as a whole as in the example shown in FIG. 5 and FIG. 6, the design layer 23 divided into a plurality of parts having a desired shape is preferably provided by printing. By providing the design layer 23 by printing, the divided design layer 23 can be provided in any shape, size, and arrangement by a simple process. The shape of the divided design layer 23 may be a circle, an approximately circle, an ellipse, an approximately ellipse, a square, a rectangle, an approximately rectangular, a parallelogram, a triangle, or the like. The method of printing the design layer 23 may be screen printing, offset printing, inkjet printing, gravure printing, or the like. Screen printing is preferred from the viewpoints of being able to coat a thick film, being able to impart an excellent metallic design, and being able to achieve high radio wave transmittance.

[0061] The surface layer 27 is formed. For example, an ionizing radiation curable resin composition is applied so as to cover the design layer 23. The composition is irradiated with an electron beam to cure the composition, thereby forming the surface layer 27.

[0062] Through the above steps, the decorative sheet 20 is manufactured.

[0063] The decorative sheet 20 is formed. The decorative sheet 20 is formed, for example, by vacuum forming. The decorative sheet 20 extends to have a shape that conforms to the surface of the decorative member 10 from which the decorative sheet 20 is manufactured. The decorative sheet 20 may be formed to be larger than the decorative member 10. The vacuum formed decorative sheet 20 may be trimmed to match the surface shape of the decorative member 10.

[0064] The molded portion 11 is formed on the surface of the decorative sheet 20 opposite to the surface on which the surface layer 27 is provided. The molded portion 11 may be provided directly on the decorative sheet 20 by injection molding such as insert molding, or may be provided by TOM molding, or may be provided by molding using other methods.

[0065] Through the above steps, the decorative member 10 is manufactured.

[0066] Conventional decorative members include a vapor-deposited film of a metal such as indium. The decorative member including the vapor-deposited film of a metal displays a metallic design. The vapor-deposited film of a metal allows radio waves to pass through. It is costly to manufacture a decorative member by vapor-depositing a metal.

[0067] In the decorative sheet 20 of this embodiment, the design layer 23 contains metal flakes. The metal flakes are not formed by vapor deposition. The metal flakes allow the decorative sheet 20 to display an excellent metallic design. The design layer 23 is formed with an opening 24 for transmitting radio waves. The opening 24 for transmitting radio waves allows radio waves to transmit through the design layer 23 even if the design layer 23 contains metal flakes. The decorative sheet 20 including the design layer 23 can be produced without vapor deposition of metal. The decorative member 10 can be manufactured from the decorative sheet 20. A decorative member that transmits radio waves can be provided at low cost.

[0068] The total light transmittance of the decorative sheet 20 is 5% or less. The visible light transmittance of the decorative sheet 20 may be 5% or less. The back surface of the decorative sheet 20 is difficult to observe. The sensor 7 and the like are difficult to visually recognize through the decorative member 10 having the decorative sheet 20.

[0069] The thickness of the design layer 23 is 1 μm or more and 40 μm or less. When the design layer 23 has a sufficient thickness, the design layer 23 can properly display the design. In particular, the design layer 23 can properly display a design with an excellent metallic look. When the design layer 23 is not too thick, radio waves can pass through the design layer 23. When the design layer 23 is not too thick, the radio wave passing opening 24 can be properly formed when a laser is irradiated onto the design film 23a.

[0070] The maximum length of the metal flakes is 1 μm or more and 50 μm or less. If the maximum length of the metal flakes is too small, the design layer 23 does not reflect light sufficiently. If the maximum length of the metal flakes is too large, the metal flakes are not oriented along the surface on which the design layer 23 is formed, and light is diffusely reflected by the design layer 23, making it difficult for the design layer 23 to display a glossy design. If the maximum length of the metal flakes is sufficiently long, the metal flakes are properly dispersed in the design layer 23 without agglomeration, and light is sufficiently reflected by the design layer 23. The design layer 23 can properly display an excellent metallic design. If the maximum length of the metal flakes is not too long, the metal flakes are easily oriented along the surface on which the design layer 23 is formed. Diffused reflection of light by the design layer 23 is suppressed. The design layer 23 can display an excellent design with a metallic luster. The metal flakes suppress diffraction of radio waves, allowing the radio waves to pass through the design layer 23 appropriately.

[0071] The content of binder resin in the design layer 23 is 50% by mass or more and 95% by mass or less. A sufficiently large amount of binder resin in the design layer 23 allows radio waves to properly transmit through the design layer 23 and allows the metal flakes to be properly dispersed in the design layer. A not too large amount of binder resin in the design layer 23 allows the metal flakes to provide the design layer 23 with an excellent metallic design.

[0072] The surface resistivity of the design layer 23 is 1.0×10 5 The surface resistivity of the design layer 23 is Ω / □ or more. When the surface resistivity of the design layer 23 is sufficiently high, radio waves can be transmitted through the design layer 23 appropriately.

[0073] The light-shielding layer 25 is made of a non-conductive material. Radio waves can be appropriately transmitted through the light-shielding layer 25. The light-shielding layer 25 may cover the radio wave transmitting opening 24. Since light is less likely to transmit through the radio wave transmitting opening 24, the sensor 7 and the like are less likely to be visually recognized through the decorative member 10 having the decorative sheet 20.

[0074] The decorative sheet 20 of this embodiment comprises a substrate 21, and a design layer 23 and a light-shielding layer 25 superimposed on the substrate 21. A radio wave transmitting opening 24 is formed in the design layer 23. The design layer 23 contains metal flakes. According to the decorative sheet 20 of this embodiment, the metal flakes allow the decorative sheet 20 to display an excellent metallic design. The radio wave transmitting opening 24 allows radio waves to transmit through the design layer 23 even though the design layer 23 contains metal flakes. The decorative member 10 can be manufactured from the decorative sheet 20. A decorative member that transmits radio waves can be provided at low cost.

[0075] Various modifications can be made to this embodiment.

[0076] In the above-described embodiment, the design layer 23 is provided with the radio wave transmission opening 24, but the light-shielding layer 25 is not provided with an opening. As shown in FIG. 8, the light-shielding layer 25 may be provided with the second radio wave transmission opening 26. The second radio wave transmission opening 26 may overlap the radio wave transmission opening 24. In a plan view, the radio wave transmission opening 24 and the second radio wave transmission opening 26 may be provided at the same position. The second radio wave transmission opening 26 may be formed simultaneously with the radio wave transmission opening 24. For example, the second radio wave transmission opening 26 may be formed by removing the light-shielding film 25a that becomes the light-shielding layer 25 at the same time that a part of the design film 23a that becomes the design layer 23 is irradiated with a laser and removed. The light-shielding film 25a and the light-shielding layer 25 absorb lasers, particularly infrared rays.

[0077] In the modification shown in Fig. 8, the light-shielding layer 25 may be made of a conductive material. For example, the light-shielding layer 25 may contain a conductive colorant such as carbon black in an amount equal to or greater than 1 / 3 of the binder resin content. The surface resistivity of the light-shielding layer 25 is increased by the second radio wave transmitting opening 26. Specifically, the surface resistivity of the light-shielding layer 25 is set to 1.0 x 10 5 It may be Ω / □ or more, or 1.0×10 6It may be Ω / □ or more. When the surface resistivity of the light-shielding layer 25 is high, radio waves are less likely to be absorbed by the light-shielding layer 25. This allows radio waves to easily pass through the light-shielding layer 25. Radio waves can pass through the decorative sheet 20. The radio wave-transmitting opening 24 and the second radio wave-transmitting opening 26 are provided in the design layer 23 and the light-shielding layer 25 only to the extent that they do not transmit much visible light. This results in a total light transmittance of the decorative sheet 20 of 5% or less, and a visible light transmittance of 5% or less.

[0078] In the decorative member 10, the base material 21 of the decorative sheet 20 may be removed. FIG. 9 shows a process of peeling and removing the base material 21 from the decorative member 10. In the decorative sheet 20 shown in FIG. 9, the design layer 23 is located between the base material 21 and the light-shielding layer 25. The decorative sheet 20 shown in FIG. 9 is manufactured by the following method. A surface layer 27 is provided on the base material 21. A design film 23a that will become the design layer 23 is provided on the surface layer 27. A laser is irradiated onto the design film 23a to remove a part of the design film 23a, forming an opening 24 for transmitting radio waves. The design film 23a that is not irradiated with the laser becomes the design layer 23. A light-shielding layer 25 is formed. The surface of the manufactured decorative sheet 20 on which the light-shielding layer 25 is provided is placed on the molding part 11. The base material 21 is peeled off as shown by the arrow in FIG. 9.

[0079] By removing the base material 21, the decorative member 10 can be made thinner and lighter.

[0080] The aspects of the present disclosure are not limited to the above-mentioned embodiment and its modified examples, but include various modifications that a person skilled in the art may conceive, and the effects of the present disclosure are not limited to the above-mentioned embodiment and its modified examples. Various additions, modifications, and partial deletions are possible within the scope of the conceptual ideas and intent of each disclosure derived from the contents defined in the claims and their equivalents. For example, the above-mentioned modified examples can be combined. EXAMPLES

[0081] The present disclosure will be described in more detail with reference to examples. The present disclosure is not limited to the following examples.

[0082] As examples, decorative sheets with different shapes of radio wave transmitting openings were prepared. As comparative examples, decorative sheets without radio wave transmitting openings were prepared. In each of the examples and comparative examples, the base material is an acrylic resin with a thickness of 125 μm. The light-shielding layer is 9 μm thick. The design layer is 30 μm thick and contains metal flakes made of aluminum. The radio wave transmitting openings are provided in the design layer by laser processing, and the second radio wave transmitting openings are provided in the light-shielding layer. The radio wave transmitting openings and the second radio wave transmitting openings overlap each other.

[0083] The radio wave transmitting openings in Example 1 were provided in circles at lattice points of a square lattice as shown in Fig. 3. The radio wave transmitting openings in Example 2 were provided in lines extending parallel to each other as shown in Fig. 4. The radio wave transmitting openings in Example 3 were provided in lines extending in a lattice pattern as shown in Fig. 5.

[0084] For each of the Examples and Comparative Examples, a PNA microwave network analyzer N5227A (manufactured by Keysight Technologies) was used to measure the transmittance and attenuation of radio waves in the manner described above. For each of the Examples and Comparative Examples, a transmission densitometer (GretagMacbeth D200-II measuring tube "V(λ)") was used to measure the optical density in the manner described above. For each of the Examples and Comparative Examples, a spectrophotometer (Konica Minolta "CM-700d") was used to measure the L * a * b * L in color space * Value of SCI L * ) was measured. * a * b * In color space, a * The value of SCI a * ) and b * The value of SCI b * ), and L from specular reflection only under similar conditions * a * b * L in color space * The value of SCE L* ), a * The value of SCE a * ) and b * The value of SCE b * ) and specular gloss were measured. The specular gloss was measured in accordance with Method 3 of JIS Z8741:1997 using a micro-TRI-gloss Cat. No. 4563 manufactured by BYK-Gardner, with an incident angle of 60°. The measurement results are shown in Table 1 below.

[0085] [Table 1]

[0086] As can be seen from each of the Examples and Comparative Examples, the provision of an opening for transmitting radio waves improves the radio wave transmittance. Specifically, the provision of an opening for transmitting radio waves makes it possible to increase the radio wave transmittance to 70% or more. Radio waves can easily pass through the decorative sheet. By providing such a decorative sheet on a molding portion, the decorative member can be easily manufactured. [Explanation of symbols]

[0087] 1. Mobile 3 Sensor System 5 Emblem 7 Sensors 10 Decorative materials 11 Molding section 20 Decorative sheet 21 Base material 23 Design Layer 24 Radio wave transmission opening 25 Light blocking layer 26 2nd radio wave transmission opening 27 Surface layer

Claims

1. A substrate; A design layer and a light-shielding layer are laminated on the base material, The design layer has an opening for transmitting radio waves formed therein, The decorative sheet, wherein the design layer contains metal flakes.

2. The decorative sheet according to claim 1 , which has a total light transmittance of 5% or less.

3. The decorative sheet according to claim 1 , which has a visible light transmittance of 5% or less.

4. The decorative sheet according to claim 1 , wherein the design layer has a thickness of 1 μm or more and 40 μm or less.

5. The decorative sheet according to claim 1 , wherein the maximum length of the metal flakes is from 1 μm to 50 μm.

6. The design layer contains a binder resin containing the metal flakes, The decorative sheet according to claim 1 , wherein the content of the binder resin in the design layer is from 50% by mass to 95% by mass.

7. The surface resistivity of the design layer is 1.0×10 ５ The decorative sheet according to claim 1 , having a surface roughness of Ω / □ or more.

8. The light-shielding layer is made of a non-conductive material, The decorative sheet according to claim 1 , wherein the light-shielding layer covers the radio wave transmitting opening.

9. The light-shielding layer is made of a conductive material, The decorative sheet according to claim 1 , wherein the light-shielding layer is provided with a second radio wave transmitting opening that overlaps with the radio wave transmitting opening.

10. A molding portion; A design layer and a light-shielding layer are provided on the molding portion, The design layer has an opening for transmitting radio waves formed therein, The decorative member, wherein the design layer includes metal flakes.

11. A sensor; A sensor system comprising: the decorative member according to claim 10 arranged facing the sensor.

12. A step of overlaying a design film and a light-shielding film on a substrate; A step of irradiating the decorative film with a laser to remove a portion of the decorative film to form an opening for transmitting radio waves, A method for producing a decorative sheet, wherein the decorative film contains metal flakes.

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