Radio wave reflector with resin layer, and method for manufacturing radio wave reflector with resin layer

Abstract

Provided are a radio wave reflector with a resin layer, which has excellent adhesion between the radio wave reflector and the resin layer, and a method for manufacturing the radio wave reflector with the resin layer.　The radio wave reflector with a resin layer comprises: the radio wave reflector, which has a reflective surface that reflects radio waves; and the resin layer, which is disposed in contact with the reflective surface. The reflective surface has: a reflective reference surface; and a plurality of diffusion inducing parts provided on the reflective reference surface to diffuse and reflect radio waves. The diffusion inducing parts are at least one kind selected from the group consisting of diffusion inducing projection parts, which are projection parts with respect to the reflective reference surface, and diffusion inducing recessed parts, which are recessed parts with respect to the reflective reference surface. The resin layer is in contact with the reflective reference surface and the plurality of diffusion inducing parts.

Description

Radio wave reflector with resin layer, and method for manufacturing radio wave reflector with resin layer

[0001] The present invention relates to a radio wave reflector with a resin layer and a method for manufacturing a radio wave reflector with a resin layer.

[0002] Communication methods (e.g., 5G wireless communication, etc.) using high-frequency radio waves (e.g., 1 GHz to 10 THz, etc.) enable high-speed, high-capacity communication. However, high-frequency radio waves have high linearity, and if there is an obstacle or the like between the transmitting antenna and the receiving antenna, the receiving antenna may not be able to properly receive the radio waves transmitted from the transmitting antenna due to the obstacle or the like. In response to this, a method is known in which a radio wave reflector reflects the radio waves transmitted from the transmitting antenna in a specific direction that avoids the obstacle or the like, allowing the receiving antenna to receive the radio waves.

[0003] For example, Patent Document 1 discloses a radio wave reflector having a specific diffuse reflection structure.

[0004] JP 2016-144164 A

[0005] The technology described in Patent Document 1 has concerns about problems such as pattern collapse in the radio wave reflector and dust and the like getting into gaps. To solve these concerns, for example, there is a method of placing another layer on the radio wave reflector, but the inventors have found that if the adhesion between the radio wave reflector and the another layer is not good, the above problems cannot be solved.

[0006] Therefore, an object of the present invention is to provide a radio wave reflector with a resin layer that has excellent adhesion between the radio wave reflector and the resin layer. Another object of the present invention is to provide a method for manufacturing a radio wave reflector with a resin layer.

[0007] As a result of extensive investigations, the present inventors have found that the above-mentioned problems can be solved by the following configuration. [1] A radio wave reflector with a resin layer, comprising a radio wave reflector having a reflective surface that reflects radio waves, and a resin layer arranged in contact with the reflective surface, wherein the reflective surface has a reflection reference surface and a plurality of diffusion-inducing portions that are provided on the reflection reference surface and diffusely reflect the radio waves, the diffusion-inducing portions are at least one type selected from the group consisting of diffusion-inducing convex portions that are convex portions with respect to the reflection reference surface and diffusion-inducing concave portions that are concave portions with respect to the reflection reference surface, and the resin layer is in contact with the reflection reference surface and the plurality of diffusion-inducing portions. [2] The radio wave reflector with a resin layer according to [1], wherein the diffusion-inducing portions are composed of the diffusion-inducing convex portions that are hemispherical protrusions with a diameter equal to the wavelength λ of the radio waves, and the diffusion-inducing concave portions that are hemispherical depressions with a diameter equal to the wavelength λ of the radio waves, and the diffusion-inducing concave portions and the diffusion-inducing convex portions are arranged adjacent to each other. [3] The radio wave reflector with a resin layer according to [1] or [2], wherein the resin layer is a coating film. [4] The radio wave reflector with a resin layer according to any one of [1] to [3], wherein the resin layer contains a colorant. [5] The radio wave reflector with a resin layer according to any one of [1] to [4], wherein the resin layer contains a fluorine-containing resin. [6] The radio wave reflector with a resin layer according to any one of [1] to [5], wherein the resin layer contains a fluorine-containing resin having units based on fluoroolefin. [7] The radio wave reflector with a resin layer according to any one of [1] to [6], wherein the resin layer contains a fluorine-containing resin having units based on chlorotrifluoroethylene and units based on vinyl ether. [8] A method for producing a radio wave reflector with a resin layer according to any one of [1] to [7], comprising: a step A of producing a radio wave reflector having a reflective surface that reflects radio waves; and a step B of applying a coating composition to the reflective surface of the radio wave reflector obtained in the step A, thereby forming the resin layer on the reflective surface.

[0008] According to the present invention, it is possible to provide a radio wave reflector with a resin layer that has excellent adhesion between the radio wave reflector and the resin layer, and also to provide a method for manufacturing a radio wave reflector with a resin layer.

[0009] Fig. 1 is a top view of a first embodiment of a radio wave reflector with a resin layer, and is a side cross-sectional view of the first embodiment of the radio wave reflector with a resin layer, taken along line A-A in Fig. 1. Fig. 2 is a perspective view of a second embodiment of the radio wave reflector with a resin layer. Fig. 3 is a schematic plan view of the reflecting surface of the second embodiment of the radio wave reflector with a resin layer. Fig. 4 is a top view of a third embodiment of the radio wave reflector with a resin layer, and is a side cross-sectional view of the third embodiment of the radio wave reflector with a resin layer, taken along line A-A in Fig. 5.

[0010] The meanings of terms used in the present invention are as follows. A numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the upper and lower limits. In the numerical ranges described in this specification in stages, the upper or lower limit described in a certain numerical range may be replaced with the upper or lower limit of another staged numerical range. Furthermore, in the numerical ranges described in this specification, the upper or lower limit described in a certain numerical range may be replaced with a value shown in the Examples. In this specification, each component may be used alone or in combination with two or more substances corresponding to the component. Here, when two or more substances are used in combination for each component, the content of that component refers to the total content of the substances used in combination, unless otherwise specified. In this specification, a combination of two or more preferred embodiments is a more preferred embodiment. A unit is a collective term for an atomic group based on one molecule of the above-mentioned monomer that is formed directly by polymerization of the monomer, and an atomic group obtained by chemically converting a portion of the above-mentioned atomic group. The content (mol %) of each unit relative to all units contained in the polymer is determined by analyzing the polymer by nuclear magnetic resonance spectroscopy, and can also be determined from the amounts of components charged when producing the polymer. (Meth)acrylic is a general term for acrylic and methacrylic. The average particle size of the particles is the 50% diameter value obtained by calculating the volume average from the particle size distribution measured using a known particle size distribution measuring device (e.g., Helos-Rodos, manufactured by Sympatec) that uses laser diffraction as its measurement principle. The film thickness is a value measured using an eddy current film thickness meter (e.g., EDY-5000, manufactured by Sanko Electronics).

[0011] An example of an embodiment of the radio wave reflector with a resin layer of the present invention will be described in detail below with reference to the drawings. Note that the drawings described below are merely illustrative for explaining the present invention, and the present invention is not limited to the drawings shown below.

[0012] [First Embodiment] FIG. 1 is a top view of a first embodiment of a radio wave reflector with a resin layer. FIG. 2 is a side cross-sectional view of the first embodiment of the radio wave reflector with a resin layer, taken along line A-A in FIG. 1. The radio wave reflector 10 with a resin layer shown in FIGS. 1 and 2 includes a radio wave reflector 20 having a reflecting surface 22 and a resin layer 30 disposed in contact with the reflecting surface 22. The reflecting surface 22 is composed of a reflecting reference surface 22a and a plurality of diffusion-inducing convex portions 22b. As shown in FIGS. 1 and 2, the resin layer 30 is disposed so as to be in contact with the reflecting reference surface 22a and the plurality of diffusion-inducing convex portions 22b that constitute the diffusion-inducing portion, along the shape of the reflecting reference surface 22a. By disposing the resin layer 30 in this manner, excellent adhesion between the radio wave reflector 20 and the resin layer 30 is achieved. In FIGS. 1 and 2, only the diffusion-inducing convex portions 22b constitute the diffusion-inducing portion, but the present invention is not limited to this embodiment. As shown in FIG. 3, which will be described later, the diffusion-inducing portion may also include diffusion-inducing concave portions. 1 and 2, the entire reflective surface 22 is covered with the resin layer 30, but it is sufficient that at least a part of the reflective surface 22 is in contact with the resin layer 30.

[0013] The radio wave reflector 20 has a reflective surface 22 that reflects radio waves. When radio waves are emitted toward the radio wave reflector 20, they are reflected by the reflective surface 22 (the reflective reference surface 22a and the diffusion-inducing convex portions 22b). Examples of materials for the radio wave reflector 20 include organic materials such as conductive organic materials and metal materials, and iron, stainless steel, aluminum, copper, nickel, or combinations of these are preferred. The thickness of the radio wave reflector 20 is preferably 0.1 to 6 mm, and more preferably 0.3 to 3 mm.

[0014] The reflecting surface 22 has a reflecting reference surface 22a and a plurality of diffusion-generating protrusions 22b provided on the reflecting reference surface 22a. The plurality of diffusion-generating protrusions 22b are spaced apart from one another in the in-plane direction. The reflecting reference surface 22a is a reference surface for providing the diffusion-generating protrusions 22b, and is preferably flat, and more preferably parallel to one surface of the radio wave reflector 20. The adjacent distance La between adjacent diffusion-generating protrusions 22b is preferably 0.01 to 300 mm, more preferably 0.02 to 215 mm. In the drawing, the diffusion-generating protrusions 22b have a rectangular shape when observed from the normal direction of the reflecting reference surface 22a, but the present invention is not limited to this embodiment. The shape of the diffusion-generating protrusions when observed from the normal direction of the reflecting reference surface may be circular (perfect circle or ellipse) or polygonal. The width Lb of the diffusion-inducing protrusion 22b is preferably 0.01 to 500 mm, more preferably 0.03 to 300 mm. The height hb of the diffusion-inducing protrusion 22b is preferably 0.01 to 500 mm, more preferably 0.015 to 300 mm. The shapes of the multiple diffusion-inducing protrusions 22b may be the same or different.

[0015] As described above, the radio wave reflector 10 with a resin layer has a resin layer 30 disposed in contact with the reflecting surface 22. Furthermore, from the viewpoints of antifouling properties and adhesion, it is preferable that the resin layer 30 be disposed so as to cover the entire reflecting surface 22. Metals are hydrophilic and tend to attract inorganic contaminants such as mud and sand. Therefore, covering the entire reflecting surface with a resin layer can significantly prevent the adhesion of contaminants. Furthermore, if the surface of the resin layer is uneven, contaminants tend to accumulate in the recesses. Therefore, from the viewpoint of antifouling properties, the smoother the resin layer surface, the better. Furthermore, the resin layer 30 is preferably a coating film. The term "coating film" used herein means that the resin layer 30 is a film formed by a known application or coating method, and is preferably a layer formed by applying or coating a coating composition in step B described below. When the resin layer 30 is a coating film, the resin layer 30 can more easily contact the reflection reference surface and the multiple diffusion-inducing portions, which tends to further improve adhesion.

[0016] Furthermore, providing the radio wave reflector 20 with the resin layer 30 can also achieve the following effects. Having the resin layer 30 (particularly a resin layer containing a fluorine-containing resin) in the radio wave reflector 10 with a resin layer can prevent the diffusion-generating convex portions 22 b from collapsing, improve the impact resistance of the reflecting surface 22 (effects such as the diffusion-generating convex portions 22 b being less likely to be scratched or crushed even when an object hits the reflecting surface 22), and provide excellent stain resistance (dust does not accumulate on the reflecting reference surface 22 a and the diffusion-generating convex portions 22 b). In particular, using a resin with a low shrinkage rate upon curing can protect the diffusion-generating convex portions 22 b without damaging them when the coating is cured. Furthermore, when the radio wave reflector 20 has a microstructure, using a resin film (not corresponding to a coating film) requires high temperatures (e.g., 200°C, etc.) for compression bonding to improve adhesion, whereas a resin layer of a coating film is advantageous in that it can be compressed at low temperatures (e.g., 100°C or lower, etc.). In a high-temperature environment, the diffusion-generating convex portions 22 b may expand and contract, causing a risk of deformation of the pattern shape of the diffusion-generating convex portions 22 b, and therefore it is preferable that the pressure-bonding be possible at a lower temperature. Furthermore, by using a resin with high pigment affinity, a radio wave reflector 10 with a resin layer having a high designability can be obtained.

[0017] The thickness of the resin layer 30 is preferably hb × 1 / 2 μm or more, more preferably hb × 2 / 3 μm or more, from the viewpoint of suppressing pattern collapse and impact resistance, and even more preferably hb + 1 μm or more, from the viewpoint of antifouling properties. The upper limit is preferably hb + 50 μm or less, more preferably hb + 15 μm or less, and even more preferably hb + 5 μm or less, from the viewpoint of not interfering with the reflection of radio waves. The thickness of the resin layer 30 is the arithmetic average of thicknesses at 10 different points on the resin layer, based on the reflection reference plane.

[0018] (Resin) The resin layer 30 preferably contains a resin. The resin layer 30 is preferably formed using a coating composition containing a resin, and more preferably formed by the below-described step B. Examples of the resin include non-fluorine resins and fluorine-containing resins, and fluorine-containing resins are preferred from the viewpoints of improving adhesion to the metal plate and reducing cure shrinkage when formed into a coating film.

[0019] Specific examples of non-fluorine resins include (meth)acrylic resins, alkyd resins, polyester resins, epoxy resins, vinyl acetate resins, vinyl chloride resins, phenolic resins, modified polyester resins, acrylic silicone resins, and silicone resins.

[0020] From the viewpoint of improving adhesion to metal sheets and reducing cure shrinkage when formed into a coating film, the fluorine-containing resin preferably has a unit based on a fluoroolefin (hereinafter also referred to as "unit F-1"). A fluoroolefin is an olefin in which one or more hydrogen atoms are substituted with fluorine atoms. In a fluoroolefin, one or more hydrogen atoms not substituted with fluorine atoms may be substituted with chlorine atoms. The number of carbon atoms in the fluoroolefin is preferably 2 to 8, more preferably 2 to 4. Specific examples of fluoroolefins include CF ２ =CF ２ (TFE), CF ２ =CFCl (chlorotrifluoroethylene), CF ２ = CHF, CH ２ =CF ２ (VDF), CF ２ =CFCF ３ , C.F. ２ = CHCF ３ , C.F. ３ CH=CHF, CF ３ CF=CH ２ , formula CH ２ =CX ｆ１ (CF ２ ) ｎ１ Y ｆ１ (In the formula, X ｆ１ and Y ｆ１ are each independently a hydrogen atom or a fluorine atom, and n1 is an integer of 2 to 10.) From the viewpoint of superior adhesion, CF ２ =CF ２ , C.H. ２ =CF ２ , C.F. ２ = CFCl, CF ３ CH=CHF, CF ３ CF=CH ２ is preferred, and CF ２ =CF ２ or CF２ =CFCl is more preferred, CF ２ =CFCl is more preferred.

[0021] When the fluororesin contains the unit F-1, the content of the unit F-1 is preferably from 20 to 100 mol %, more preferably from 30 to 70 mol %, and still more preferably from 40 to 60 mol %, based on all units contained in the fluororesin, from the viewpoint of adhesion.

[0022] The fluorine-containing resin may contain a unit having at least one of an aliphatic hydrocarbon ring and an aromatic ring (hereinafter also referred to as "unit F-2"). The unit F-2 is preferably a unit based on a monomer having at least one of an aliphatic hydrocarbon ring and an aromatic ring (hereinafter also referred to as "monomer f2"). The unit F-2 is preferably a unit not containing a fluorine atom.

[0023] Specific examples of the aliphatic hydrocarbon ring include monocyclic aliphatic hydrocarbons such as cyclobutane, cyclopentane, cyclohexane, cycloheptane, and cyclooctane; polycyclic aliphatic hydrocarbons such as 4-cyclohexylcyclohexane and decahydronaphthalene; aliphatic hydrocarbons having a bridged ring structure such as norbornane and a 1-adamantyl group; and aliphatic hydrocarbons having a spiro ring structure such as a spiro[3.4]octyl group. Specific examples of the aromatic ring include aromatic hydrocarbon rings such as benzene, toluene, xylene, naphthalene, phenol, and benzoic acid; and aromatic heterocycles such as furan, thiophene, pyrrole, and pyridine.

[0024] As the monomer f2, vinyl ether, vinyl ester, allyl ether, allyl ester, or (meth)acrylic acid ester having at least one of an aliphatic hydrocarbon ring and an aromatic ring is preferable. Specific examples of the monomer f2 include cyclohexyl (meth)acrylate, cyclohexyl vinyl ether, cyclohexanedimethanol monovinyl ether (CH ２ =CHO-CH ２ -cycloC ６ H １０ -CH ２ OH), CH ２ =CHCH２ O-CH ２ -cycloC ６ H １０ -CH ２ OH, CH ２ =CHO-CH ２ -cycloC ６ H １０ -CH ２ -(OCH ２ CH ２ ) １５ OH, benzoic acid vinyl ester, tert-butyl benzoic acid vinyl ester, and benzyl (meth)acrylate. ６ H １０ "-" represents a cyclohexylene group, and "-cycloC ６ H １０ The bonding site of "-" is usually 1,4-.

[0025] When the fluororesin contains units F-2, the content of units F-2 is preferably from 1 to 50 mol %, more preferably from 5 to 45 mol %, and still more preferably from 10 to 40 mol %, based on all units contained in the fluororesin.

[0026] The fluorine-containing resin may contain a unit having neither an aliphatic hydrocarbon ring nor an aromatic ring, and having at least one of a hydroxy group and a carboxy group (hereinafter also referred to as "unit F-3"). Unit F-3 is preferably a unit having no fluorine atom.

[0027] Unit F-3 may be a unit based on a monomer having at least one of a hydroxy group and a carboxy group (hereinafter also referred to as "monomer f3"), or may be a unit obtained by converting a group convertible to a hydroxy group or a carboxy group in a fluororesin containing a unit having this group to at least one of a hydroxy group and a carboxy group. Examples of such units include units obtained by reacting a fluororesin containing a unit having a hydroxy group with a polycarboxylic acid or an acid anhydride thereof to convert some or all of the hydroxy groups to carboxy groups. At least a portion of the hydroxy groups or carboxy groups in monomer f3 may be crosslinked with a curing agent (for example, a compound having two or more isocyanate groups in one molecule, a compound having two or more epoxy groups in one molecule), or may remain without crosslinking with the curing agent.

[0028] Examples of the monomer f3 having a hydroxy group include vinyl ethers, vinyl esters, allyl ethers, allyl esters, (meth)acrylic acid esters, and allyl alcohols, all of which have a hydroxy group. Specific examples of the monomer f3 having a hydroxy group include CH ２ =CHOCH ２ CH ２ OH, CH ２ =CHCH ２ OCH ２ CH ２ OH, CH ２ =CHOCH ２ CH ２ CH ２ CH ２ OH and CH ２ =CHCH ２ OCH ２ CH ２ CH ２ CH ２ OH, and from the viewpoint of copolymerizability with fluoroolefin, CH ２ =CHCH ２ OCH ２ CH ２ OH or CH ２ =CHOCH ２ CH ２ CH ２ CH ２OH is preferred.

[0029] Examples of the monomer f3 having a carboxy group include unsaturated carboxylic acids, (meth)acrylic acid, and monomers obtained by reacting the hydroxy group of the above-mentioned monomer having a hydroxy group with a carboxylic acid anhydride. Specific examples of the monomer f3 having a carboxy group include CH ２ =CHCOOH, CH(CH ３ )=CHCOOH, CH ２ =C(CH ３ ) COOH, HOOCCH=CHCOOH, CH ２ =CH(CH ２ ) ｎ１１ COOH (where n11 is an integer of 1 to 10), CH ２ = CHO(CH ２ ) ｎ１２ OC(O)CH ２ CH ２ COOH (where n12 is an integer of 1 to 10). From the viewpoint of copolymerizability with fluoroolefin, CH ２ =CH(CH ２ ) ｎ１１ COOH or CH ２ = CHO(CH ２ ) ｎ１２ OC(O)CH ２ CH ２ COOH is preferred.

[0030] When the fluororesin contains units F-3, the content of units F-3 is preferably more than 0 mol % and not more than 30 mol %, more preferably from 1 to 15 mol %, and still more preferably from 1.5 to 5 mol %.

[0031] The fluorine-containing resin may contain units (hereinafter also referred to as units F-4) based on a monomer (hereinafter also referred to as monomer f4) that has neither an aliphatic hydrocarbon ring nor an aromatic ring and does not have a hydroxy group or a carboxy group. Units F-4 are preferably units that do not have a fluorine atom. Units F-4 may have a crosslinkable group other than a hydroxy group or a carboxy group. Specific examples of such groups include an amino group, an epoxy group, an oxetanyl group, and a hydrolyzable silyl group.

[0032] Examples of the monomer f4 include one or more selected from the group consisting of alkenes, vinyl ethers, vinyl esters, allyl ethers, allyl esters, and (meth)acrylic acid esters. From the viewpoints of copolymerizability with fluoroolefins and weather resistance of the fluorine-containing resin, at least one of vinyl ethers and vinyl esters is preferred, and vinyl ethers are more preferred.

[0033] Specific examples of the monomer f4 include ethylene, propylene, 1-butene, ethyl vinyl ether, tert-butyl vinyl ether, 2-ethylhexyl vinyl ether, vinyl acetate, vinyl pivalate, vinyl neononanoate (manufactured by HEXION, trade name "VEOVA 9"), vinyl neodecanoate (manufactured by HEXION, trade name "VEOVA 10"), and tert-butyl (meth)acrylate.

[0034] When the fluororesin contains units F-4, the content of units F-4 is preferably from 10 to 40 mol %, more preferably from 20 to 30 mol %, based on all units contained in the fluororesin.

[0035] The fluorine-containing resin preferably has a unit based on fluoroolefin from the viewpoint of adhesion to metal materials and reduction of shrinkage during coating film formation (without destroying the microstructure), and more preferably has a unit based on chlorotrifluoroethylene and a unit based on vinyl ether from the viewpoint of better adhesion. In the above case, the flexibility of the fluorine-containing resin is excellent, so that the resin layer containing the fluorine-containing resin can be more easily brought into contact with the reflection reference surface and the plurality of diffusion-inducing portions, and the adhesion can be further improved.

[0036] Two or more types of fluorine-containing resins may be used in combination. When the resin layer contains a fluorine-containing resin, the content of the fluorine-containing resin is preferably 50 to 90 mass %, more preferably 60 to 80 mass %, based on the total mass of the resin layer.

[0037] Fluorine-containing resins are produced by known methods. For example, they can be obtained by copolymerizing each monomer in the presence of a solvent and a radical polymerization initiator. Methods for producing fluorine-containing resins include solution polymerization and emulsion polymerization. During or after the production of the fluorine-containing resin, a polymerization stabilizer, a polymerization inhibitor, a surfactant, and the like may be used, if necessary.

[0038] As the fluorine-containing resin, commercially available products may be used, and examples thereof include the "Lumiflon" series (manufactured by AGC), the "Fluon" series (manufactured by AGC), the "Kynar" series (manufactured by Arkema), the "Zeffle" series (manufactured by Daikin Industries, Ltd.), the "Eterflon" series (manufactured by Eternal), and the "Zendura" series (manufactured by Honeywell).

[0039] (Colorant) The resin layer may contain a colorant. It is expected that the radio wave reflector with a resin layer will be installed in a conspicuous location, and if it has the appearance of metal itself, it will be particularly conspicuous. Therefore, from the viewpoint that design is important, it is preferable that a colorant is contained. The colorant can be appropriately selected depending on the design and application, and examples thereof include color pigments and extender pigments. Specific examples of color pigments include black pigments such as carbon black, copper oxide, iron oxide black, manganese dioxide, aniline black, and activated carbon; yellow pigments such as lead yellow, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navel yellow, naphthol yellow S, Hansa yellow, benzidine yellow G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, and tartrazine lake; red iron oxide, cadmium red, red lead, mercury sulfide, cadmium, permanent red 4R, lithol red, pyrozolone red, watching red, calcium salts, Examples of suitable pigments include red pigments such as Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, and Brilliant Carmine 3B; blue pigments such as Prussian Blue, Cobalt Blue, Alkali Blue Lake, Victoria Blue Lake, Phthalocyanine Blue, Metal-Free Phthalocyanine Blue, Partially Chlorinated Phthalocyanine Blue, Fast Sky Blue, and Indanthrene Blue BC; green pigments such as Chrome Green, chromium oxide, Pigment Green B, Malachite Green Lake, and Final Yellow Green G; and white pigments such as zinc oxide, titanium oxide, antimony white, and zinc sulfide. Specific examples of extender pigments include silica, talc, mica, calcium carbonate, clay, kaolin, and barium sulfate.

[0040] (Additives) The resin layer may contain additives in addition to the various components described above. Examples of the additives include a curing agent, a curing catalyst, an ultraviolet absorber, a matting agent, a leveling agent, a surface conditioner, a degassing agent, a filler, a thickener, a dispersant, a surfactant, an antistatic agent, a rust inhibitor, a silane coupling agent, an antifouling agent, a stain-reducing treatment agent, and a plasticizer.

[0041] [Second Embodiment] Figure 3 is a perspective view of a second embodiment of a radio wave reflector with a resin layer. The radio wave reflector 50 with a resin layer shown in Figure 3 includes a radio wave reflector 60 having a reflective surface 62 that reflects radio waves, and a resin layer 70. The resin layer 70 is disposed in contact with the reflective surface 62, and is disposed so as to contact the reflective reference surface 62a of the reflective surface 62 and the diffusion convex portions 62b and the diffusion concave portions 62c of the diffusion portion 63, and to cover the entire reflective surface 62. By disposing the resin layer 70 in this manner, the adhesion between the radio wave reflector 60 and the resin layer 70 and the anti-fouling properties are excellent. Metals are hydrophilic and tend to attract inorganic contaminants such as mud and sand. Therefore, by disposing the resin layer so as to cover the entire reflective surface, it is possible to significantly prevent the adhesion of contaminants. Furthermore, since an uneven surface of the resin layer tends to accumulate contaminants in the concave portions, the smoother the surface of the resin layer, the better from the viewpoint of anti-fouling properties. The aspects of each member in the radio wave reflector 50 with a resin layer are the same as those of each member described in the first embodiment above, except for the points detailed below, and the preferred aspects are also the same.

[0042] In FIG. 3 , the diffusion-generating portion 63 is composed of a diffusion-generating protrusion 62b, which is a hemispherical protrusion with a diameter equal to the wavelength λ of the radio wave, and a diffusion-generating recess 62c, which is a hemispherical depression with a diameter equal to the wavelength λ of the radio wave, relative to the reflecting reference surface 62a. The hemispherical protrusion of the diffusion-generating protrusion 62b is not limited to a perfect hemisphere, but may also be a nearly perfect hemisphere. The diameter of the diffusion-generating protrusion 62b varies depending on the wavelength λ of the radio wave emitted to the reflecting surface 62. The wavelength λ of the radio wave is preferably 0.01 to 500 mm, and more preferably 0.03 to 300 mm. The height of the hemisphere of the diffusion-generating protrusion 62b corresponds to the radius of the hemisphere, and is therefore λ / 2. Note that while the above description was given for the diffusion-generating protrusion 62b, the same applies to the hemispherical depression of the diffusion-generating protrusion 62c.

[0043] Furthermore, the diffusion convex portions 62b and the diffusion concave portions 62c are arranged adjacent to each other. Specifically, for any one diffusion concave portion 62c, a plurality of diffusion concave portions 62c are arranged at positions where the adjacent distance Lc is shortest, and the diffusion convex portions 62b and the diffusion concave portions 62c are arranged alternately at equal intervals on a straight line including the adjacent distance Lc. By arranging the diffusion convex portions 62b and the diffusion concave portions 62c alternately in this manner, excellent reflection characteristics can be achieved. The adjacent distance Lc is the wavelength λ of the radio wave × n Ｌ is preferred. Ｌ is preferably 0 to 2.0, and more preferably 0.1 to 1.0. The adjacent distance Lc is the distance from the outer periphery of the hemisphere of the diffusion-generating convex portion 62b to the outer periphery of the hemisphere of the diffusion-generating concave portion 62c on the reflecting reference surface 62a. For example, when the adjacent distance Lc is 0, the hemisphere of the diffusion-generating convex portion 62b and the hemisphere of the diffusion-generating concave portion 62c are in contact with each other.

[0044] Fig. 4 is a schematic plan view of a second embodiment of a radio wave reflector with a resin layer. In Fig. 4, in the radio wave reflector 50 with a resin layer, a diffusion-generating recess 62b, which is a hemispherical protrusion with a diameter λ, and a diffusion-generating recess 62c, which is a hemispherical depression with a diameter λ, constitute the diffusion portion 63. The diffusion-generating protrusion 62b and the diffusion-generating recess 62c are arranged on the reflection reference surface 62a so as to be adjacent to each other at a constant distance Lc. The reflection surface 62 is covered with a resin layer (not shown).

[0045] [Third Embodiment] FIG. 5 is a top view of a third embodiment of a radio wave reflector with a resin layer. FIG. 6 is a side cross-sectional view of the third embodiment of a radio wave reflector with a resin layer, taken along line A-A in FIG. 5. The radio wave reflector 80 with a resin layer shown in FIGS. 5 and 6 includes a radio wave reflector 20 having a reflecting surface 22 and a resin layer 30 disposed in contact with the reflecting surface 22. The reflecting surface 22 is composed of a reflecting reference surface 22a and a plurality of diffusion-inducing convex portions 22c. As shown in FIGS. 5 and 6, the resin layer 30 is disposed so as to be in contact with the reflecting reference surface 22a and the plurality of diffusion-inducing convex portions 22c that constitute the diffusion-inducing portion, along the shapes of the reflecting reference surface 22a and the plurality of diffusion-inducing convex portions 22c that constitute the diffusion-inducing portion. Disposing the resin layer 30 in this manner ensures excellent adhesion between the radio wave reflector 20 and the resin layer 30. In FIGS. 5 and 6, only the diffusion-inducing convex portions 22c constitute the diffusion-inducing portion, but the present invention is not limited to this embodiment. As shown in FIG. 3 described above, the diffusion-inducing portion may include diffusion-inducing concave portions. 5 and 6 , the entire reflective surface 22 is covered with the resin layer 30. However, it is sufficient that at least a portion of the reflective surface 22 is in contact with the resin layer 30. However, from the viewpoints of anti-fouling properties and adhesion, it is preferable that the resin layer 30 be disposed so as to cover the entire reflective surface 22. Metals are hydrophilic and easily attract inorganic contaminants such as mud and sand. Therefore, covering the entire reflective surface with a resin layer can significantly prevent the adhesion of contaminants. Furthermore, if the surface of the resin layer is uneven, contaminants tend to accumulate in the recesses. Therefore, from the viewpoint of anti-fouling properties, the smoother the resin layer surface, the better. Furthermore, as shown in FIG. 5 , the multiple diffusion-inducing convex portions 22c extend along the y-axis direction and are spaced apart from each other along the x-axis direction. The preferred embodiments of each component of the radio wave reflector 80 with a resin layer are the same as those of the radio wave reflector 10 with a resin layer described above. In particular, the preferred ranges of the adjacent distance La between adjacent diffusion-generating convex portions 22c, the width Lb of the diffusion-generating convex portion 22c, and the height hb of the diffusion-generating convex portion 22c shown in Figures 5 and 6 are the same as the preferred ranges of each symbol described in the first embodiment.

[0046] [Other Embodiments] The radio wave reflector with a resin layer of the present invention may be modified as follows in the first, second, and third embodiments. The diffusion-inducing portion is at least one type selected from the group consisting of diffusion-inducing convex portions and diffusion-inducing concave portions, and may be either diffusion-inducing convex portions or diffusion-inducing concave portions, or both. The shapes of the multiple diffusion-inducing convex portions may be the same as or different from each other. The shapes of the multiple diffusion-inducing concave portions may be the same as or different from each other. When the diffusion-inducing concave portions are square prisms, the height and width of the square prisms are the same as the preferred height and width values ​​of the diffusion-inducing convex portions described above. Examples of the shape of the diffusion-inducing portion include cones such as cones and pyramids, truncated cones such as truncated cones and truncated pyramids, prisms such as cylinders and prisms, and hemispheres (semispheres). A truncated cone, a prism, or a hemisphere is preferred. In FIG. 2, the reflecting surface 22 has a lattice pattern, but other patterns are also possible. The reflecting surface 22 may have one or more patterns. Furthermore, the reflecting surface 22 may have a pattern in some regions and not in other regions. While the reflecting surface 22 has the diffusion-generating protrusions 62b and the diffusion-generating recesses 62c in Fig. 3, for example, the diffusion-generating protrusions 62b may be disposed instead of the diffusion-generating recesses 62c, or the diffusion-generating recesses 62c may be disposed instead of the diffusion-generating protrusions 62b. In other words, the reflecting surface 22 may have only the diffusion-generating protrusions 62b or only the diffusion-generating recesses 62c, or the arrangement of the diffusion-generating protrusions 62b and the diffusion-generating recesses 62c may be reversed.

[0047] [Method for manufacturing a radio wave reflector with a resin layer] The method for manufacturing a radio wave reflector with a resin layer of the present invention may be a known manufacturing method. The method for manufacturing a radio wave reflector with a resin layer of the present invention is preferably a method for manufacturing a radio wave reflector with a resin layer, comprising step A of manufacturing a radio wave reflector having a reflective surface that reflects radio waves, and step B of applying a coating composition to the reflective surface of the radio wave reflector obtained in step A to form a resin layer on the reflective surface.

[0048] <Step A> Step A is a step of manufacturing a radio wave reflector having a reflective surface. Methods for forming a reflective surface on a radio wave reflector include, for example, a method of pouring raw material for the radio wave reflector into a mold, a method of using a transfer drum formed with a desired shape, and a cutting method using a laser or the like.

[0049] <Step B> Step B is a step of applying a coating composition to the reflecting surface of the radio wave reflector to form a resin layer.

[0050] Examples of methods for applying the coating composition include spray coating, squeegee coating, flow coating, bar coating, spin coating, dip coating, screen printing, gravure printing, die coating, inkjet printing, curtain coating, and methods using a brush and spatula. If necessary, a treatment of drying after application to remove the solvent may be performed. The drying temperature is preferably 0 to 50°C, and the drying time is preferably 1 minute to 2 weeks.

[0051] The coating composition is preferably a composition containing a resin. Examples of the resin include the resins that can be contained in the resin layer described above. In addition, the coating composition may contain various components that can be contained in the resin layer described above, as well as an organic solvent.

[0052] The coating composition may be a coating composition in which the resin is dissolved or dispersed in a liquid medium, or a coating composition that is substantially free of a liquid medium (e.g., a powder coating composition). Examples of liquid media include organic solvents and water. Examples of coating compositions dissolved or dispersed in a liquid medium include coating compositions dissolved in organic solvents (e.g., solvent-based coating compositions) and coating compositions dispersed in water (e.g., aqueous coating compositions). Aqueous coating compositions are preferred from the perspective of reducing environmental impact. Note that solvent-based coating compositions are more preferred from the perspective of improving the surface smoothness of the resin layer surface. When the coating composition is substantially free of a liquid medium, it means that the content of the liquid medium is 0.1% by mass or less relative to the total mass of the coating composition.

[0053] Examples of organic solvents include ketone-based solvents, ester-based solvents, hydrocarbon-based solvents, alcohol-based solvents, glycol ether-based solvents, and glycol ester-based solvents. Specific examples of ketone-based solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, and diacetone alcohol. Specific examples of ester-based solvents include ethyl acetate and butyl acetate. Specific examples of hydrocarbon-based solvents include hexane, heptane, cyclohexane, xylene, ethylbenzene, toluene, ExxonMobil's Solvesso 100 and ExxonMobil's Solvesso 150, and aromatic hydrocarbon solvents (e.g., mineral spirits). Specific examples of alcohol-based solvents include butyl alcohol. Specific examples of glycol ether-based solvents include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and propylene glycol monopropyl ether. Specific examples of glycol ester-based solvents include 1-methoxypropyl-2-acetate.

[0054] When the coating composition contains a liquid medium, the content of the liquid medium is preferably 10 to 95 mass %, more preferably 20 to 90 mass %, based on the total mass of the coating composition, and the content of the resin is preferably 50 to 80 mass %, more preferably 60 to 80 mass %, based on the total solid content of the coating composition.

[0055] The present invention will be described in detail below with reference to examples. Examples 1 to 4 are working examples, but the present invention is not limited to these examples.

[0056] Example 1 Aqueous coating composition 1 was prepared by adding the various components shown in the table to an aqueous dispersion of fluorine-containing resin P1. Next, coating composition 1 was applied to the reflecting surface of radio wave reflector X using a doctor blade so that the thickness of the coating before drying was 4 mm, forming a coating film. The coating film was then dried at 80°C for 30 minutes to obtain the radio wave reflector with a resin layer of Example 1. The thickness of the resin layer was 115 μm. Note that radio wave reflector X is the radio wave reflector in FIG. 5 , with La of 150 μm, Lb of 75 μm, and hb of 100 μm, and is made of nickel. The obtained radio wave reflector with a resin layer of Example 1 corresponds to radio wave reflector 80 with a resin layer in FIG. 5 . The composition of the fluororesin P1 was CTFE units / CHVE units / EVE units / CHMVE units / CM-EOVE units = 50 / 17 / 22.5 / 11 / 0.5 (molar ratio). CTFE: chlorotrifluoroethylene CHVE: cyclohexyl vinyl ether EVE: ethyl vinyl ether CHMVE: cyclohexanedimethanol monovinyl ether CM-EOVE: CH ２ =CHOCH ２ -cycloC ６ H １０ -CH ２ O (CH ２ CH ２ O) １５ H

[0057] Example 2 An aqueous coating composition (coating composition 2) was prepared by adding the various components shown in the table to an aqueous dispersion containing fluorine-containing resin P2 (Zeffle SE310, manufactured by Daikin Corporation, TFE units / VDF units / methacrylate-based units = 29 / 44 / 27 (molar ratio)). Next, coating composition 2 was applied to the reflecting surface of radio wave reflector X using a doctor blade so that the thickness of the coating before drying was 4 mm, thereby forming a coating film. The coating film was then dried at 80°C for 30 minutes, and the radio wave reflector with a resin layer of Example 2 was obtained.

[0058] Example 3 An aqueous coating composition (coating composition 3) was prepared by adding the various components shown in the table to an aqueous dispersion containing non-fluorinated resin P3 (U-Double 771SI, manufactured by Nippon Shokubai Co., Ltd., an acrylic silicone resin). Next, coating composition 3 was applied to the reflecting surface of radio wave reflector X using a doctor blade so that the thickness of the coating before drying was 4 mm, forming a coating film. The coating film was then dried at 80°C for 30 minutes, yielding the radio wave reflector with a resin layer of Example 3.

[0059] [Example 4] A solvent-based coating composition (coating composition 4) was prepared by adding various components shown in Table 2 to a solution dispersion of fluorine-containing resin P4. Next, coating composition 4 was applied to the reflective surface of radio wave reflector X using a doctor blade so that the thickness of the coating before drying was 4 mm, forming a coating film. The coating film was then dried at room temperature (23°C) for 7 days to obtain the radio wave reflector with a resin layer of Example 4. The composition of fluorine-containing resin P4 was CTFE unit / CHVE unit / EVE unit / HBVE unit = 50 / 15 / 25 / 10 (molar ratio). CTFE: chlorotrifluoroethylene CHVE: cyclohexyl vinyl ether EVE: ethyl vinyl ether HBVE: hydroxybutyl vinyl ether

[0060] PFC105: Typek PFC105 (manufactured by Ishihara Sangyo Kaisha), titanium oxide pigment BYK-190: DISPERBYK (registered trademark)-190, pigment dispersant Dehydran 1620: BASF, antifoaming agent CS-12: JNC, film-forming aid Bermodor 2150: AkzoNobel, urethane associative thickener Coronate HX: Nippon Polyurethane, hardener Dibutyltin dilaurate dilution: dibutyltin dilaurate diluted with xylene to a concentration of 1 / 10,000, hardening catalyst

[0061] [Adhesion] The adhesion between the radio wave reflector and the resin layer was determined by the cross-cut method (JIS K 5600-5-6). Specifically, the surface of the resin layer side of each radio wave reflector with a resin layer was cut into a grid of 100 squares at 1 mm intervals, adhesive tape (Cellotape (registered trademark)) was applied to the resin layer, and the adhesive tape was subsequently peeled off at a 45° angle. The adhesion was evaluated based on the number of squares (number of squares / 100) out of 100 squares that did not cause the resin layer to peel off from the radio wave reflector due to the adhesive tape, using the following evaluation criteria. A rating of C or higher was acceptable. "A": Number of squares more than 95 "B": Number of squares more than 85 and not more than 95 "C": Number of squares more than 70 and not more than 85 "D": Number of squares not more than 70

[0062] [Surface Smoothness] The surface roughness (Ra1) of the resin layer side of each radio wave reflector with a resin layer and the surface roughness (Ra0) of the reflecting surface side of a radio wave reflector without a resin layer were measured using a laser microscope (VK-X3000, manufactured by KEYENCE Corporation), and the surface smoothness was evaluated according to the following evaluation criteria. A rating of C or higher is acceptable. If Ra1 is lower than Ra0, this means that the resin layer is in closer contact with the reflecting surface of the radio wave reflector, or in other words, this means that there is less space, such as an air layer, between the resin layer and the reflecting surface. "A": 0≦Ra0−Ra1 "B": −0.002≦Ra0−Ra1<0 "C": −0.01≦Ra0−Ra1<−0.002 "D": Ra0−Ra1<−0.01 Furthermore, when focusing only on the Ra1 value, the smaller the Ra1 value, the higher the surface smoothness of the resin layer surface itself, and therefore it can be said that dirt is less likely to accumulate on the resin layer surface.

[0063]

[0064]

[0065] As shown in Tables 1 and 2, it was confirmed that the radio wave reflector with a resin layer of the present invention had excellent adhesion (Examples 1 to 4). Furthermore, the radio wave reflector with a resin layer of the present invention showed no destruction of the microstructure and showed little shrinkage on curing when formed into a coating film. It was confirmed that when the resin layer contained a fluorine-containing resin having units based on chlorotrifluoroethylene and units based on vinyl ether, the adhesion and surface smoothness were even better (Examples 1 and 4). It was also confirmed that when an organic solvent was used as the liquid medium, the surface smoothness was even better (Example 4).

[0066] The entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2023-205949, filed on December 6, 2023, are incorporated herein by reference as part of the disclosure of the present invention.

[0067] 10, 50, 80 Radio wave reflector with resin layer 20, 60 Radio wave reflector 22, 62 Reflecting surface 22a, 62a Reflecting reference surface 22b, 62b Diffusion-generating convex portion 30, 70 Resin layer 62c Diffusion-generating concave portion

Claims

1. A radio wave reflector with a resin layer, comprising a radio wave reflector having a reflective surface that reflects radio waves, and a resin layer arranged in contact with the reflective surface, wherein the reflective surface has a reflective reference surface and a plurality of diffusion generating portions provided on the reflective reference surface that diffusely reflect the radio waves, wherein the diffusion generating portions are at least one type selected from the group consisting of diffusion generating convex portions that are convex portions relative to the reflective reference surface, and diffusion generating concave portions that are concave portions relative to the reflective reference surface, and wherein the resin layer is in contact with the reflective reference surface and the plurality of diffusion generating portions.

2. A radio wave reflector with a resin layer as described in claim 1, wherein the diffusion-inducing portion is composed of the diffusion-inducing convex portion which is a hemispherical protrusion with a diameter equal to the wavelength λ of the radio wave, and the diffusion-inducing concave portion which is a hemispherical depression with a diameter equal to the wavelength λ of the radio wave, and the diffusion-inducing concave portion and the diffusion-inducing convex portion are arranged adjacent to each other.

3. The radio wave reflector with a resin layer according to claim 1 or 2, wherein the resin layer is a coating film.

4. The radio wave reflector with a resin layer according to claim 1 or 2, wherein the resin layer contains a colorant.

5. The radio wave reflector with a resin layer according to claim 1 or 2, wherein the resin layer contains a fluorine-containing resin.

6. The radio wave reflector with a resin layer according to claim 1 or 2, wherein the resin layer contains a fluorine-containing resin having a unit based on a fluoroolefin.

7. The radio wave reflector with a resin layer according to claim 1 or 2, wherein the resin layer contains a fluorine-containing resin having a unit based on chlorotrifluoroethylene and a unit based on vinyl ether.

8. A method for producing a radio wave reflector with a resin layer as described in claim 1 or 2, comprising: step A of producing a radio wave reflector having a reflective surface that reflects radio waves; and step B of applying a coating composition to the reflective surface of the radio wave reflector obtained in step A, thereby forming the resin layer on the reflective surface.

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