Coating material containing metamaterial, and spraying device and application method therefor

Abstract

The purpose of the present disclosure is to make it possible to add new functionality using a metamaterial without limiting the shape of an object.　The present disclosure is a coating material comprising a solvent of any color and a powdery metamaterial that is added to the solvent and in which meta-atoms are covered with a resin.

Description

Paint containing metamaterials, spraying apparatus and application method thereof

[0001] This disclosure relates to a paint containing a metamaterial, a spraying apparatus therefor, and a method for applying the same.

[0002] Structures (hereinafter referred to as metamaterials) have been proposed that artificially create properties different from those of materials found in nature. Metamaterials and metaatoms have a relationship similar to that between bulk and the atoms that make up a substance. The unit structure that constitutes a metamaterial is the metaatom.

[0003] Metamaterials fabricated to date include metamaterials in which a split-ring resonator is fabricated on a resin wall surface (see, for example, Non-Patent Document 1), and multilayer metamaterials (see, for example, Non-Patent Document 2).

[0004] D. Bruce et al. adv. mater, 22, 5053-5057, 2010N. Liu et al. nature. mater, 7 31-37, 2008

[0005] When adding new functionality to existing objects using metamaterials, metaatoms were formed on a film, and the film was then attached to the existing object. However, attaching films to complex shapes was difficult, limiting the types of objects to which new functionality using metamaterials could be added.

[0006] This disclosure aims to enable the addition of new functions using metamaterials without limitations on the shape of an object.

[0007] Because metamaterials are covered with resin, they have the property of not bonding with each other. Therefore, in this disclosure, metamaterials are added to a paint. That is, the paint of this disclosure comprises a solvent having an arbitrary color and a powdery metamaterial added to the solvent, in which metaatoms are covered with resin.

[0008] This disclosure makes it possible to add new functions using metamaterials to an object simply by applying a paint to it. Therefore, this disclosure makes it possible to add new functions using metamaterials without any limitations on the shape of the object.

[0009] The color of the resin in the metamaterial may be the same as the color of the solvent.

[0010] As mentioned above, metamaterials added to paint are less prone to uneven distribution or separation within the paint, and the orientation of metaatoms becomes random. Therefore, the coating apparatus of this disclosure applies the metamaterial by spraying. The method for implementing the metamaterial function of this disclosure involves spraying the paint of this disclosure onto the surface of an object. By employing spraying for coating in this way, the orientation of metaatoms becomes even more random, making it possible to impart uniform properties to the object that are independent of polarization and incident angle.

[0011] Furthermore, the above disclosures can be combined as much as possible.

[0012] According to this disclosure, it is possible to add new functions using metamaterials without being restricted by the shape of the object.

[0013] An example of metamaterial powder is shown. An example of the paint of this disclosure is shown. An example of coating an object with the paint is shown. An example of the state of the coating film applied to an object with the paint is shown. An example of the configuration of the nozzle portion of the spraying device of this embodiment is shown. An example of the configuration of the nozzle portion of the spraying device of this embodiment is shown.

[0014] Embodiments of this disclosure will be described in detail below with reference to the drawings. However, this disclosure is not limited to the embodiments shown below. These examples are illustrative, and this disclosure can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. In this specification and in the drawings, components with the same reference numerals refer to the same components.

[0015] (First Embodiment) Figure 1 shows an example of metamaterial powder. The metamaterial powder 11 shown in Figure 1 can be described as a fine powder in which metaatoms are covered with resin. The size of the metamaterial powder varies depending on the size of the metaatoms, and examples include 200 μm to 400 μm. However, the size of the metamaterial powder in this disclosure can be any value between 40 μm and 700 μm.

[0016] Examples of the functions of the metamaterial 11 powder include the absorption, reflection, transmission, or blocking of radio waves of a desired frequency. For example, by using metamaterial 11 powder that absorbs, reflects, or blocks infrared rays, a thermal insulation effect can be added. The properties can be controlled by mixing multiple types of metamaterial 11 powder.

[0017] The constituent materials of the metaatoms that make up the metamaterial powder are not particularly limited. For example, the constituent materials can be conductive materials, dielectrics, or semiconductors (semiconductor materials), and conductive materials are preferred.

[0018] Examples of conductive materials include metals, conductive metal oxides, conductive polymer materials, and nanocarbon materials (e.g., graphene, carbon nanotubes, etc.), with materials having low conductivity loss being preferred. Examples of metals or conductive metal oxides include gold, silver, copper, aluminum, iron, nickel, chromium, titanium, tungsten, stainless steel, oxides of these metals (e.g., conductive titanium oxide, tungsten oxide, etc.), and other conductive metal oxides (e.g., indium tin oxide (ITO), indium zinc oxide (IZO), etc.). In other words, it is preferable that the conductive material contains at least one metal selected from gold, silver, copper, aluminum, iron, nickel, chromium, titanium, tungsten, stainless steel, indium, tin, and zinc. These metals may be in the form of compounds (oxides, etc.) as long as they are conductive. On the other hand, examples of conductive polymer materials include known conductive polymers, etc.

[0019] The conductive material may be used alone or in combination of two or more materials. In particular, from the viewpoint of raw material costs and process costs, it is more preferable that the conductive material includes at least one of aluminum, copper, and gold.

[0020] Furthermore, the shape of the metaatom is not particularly limited as long as it exhibits optical responsiveness to the desired frequency band, and can be, for example, circular (including elliptical), ring-shaped, square, rectangular, cross-shaped, swastika-shaped, or other polygonal shapes.

[0021] Here, the desired frequency band in this disclosure can be any value of electromagnetic waves from millimeter waves and terahertz waves to the infrared region, ranging from 0.03 THz to 450 THz. This disclosure is not particularly limited as long as it exhibits electromagnetic responsiveness in the said frequency band, and for example, the shape of the metaatom can be any shape.

[0022] The resin constituting the metamaterial powder is made of any non-conductive material capable of transmitting a desired frequency band, and is not limited to resins. Examples of resins include cycloolefin polymer (COC / COP), polyethylene (PE), polymethylpentene (PMP), Teflon® (PTFE), polycarbonate (PC), polypropylene (PP), acrylic resin (PMMA), ABS resin, and combinations thereof. Furthermore, the shape of the resin can be any shape as long as it can encapsulate the metaatom.

[0023] Here, the metamaterial 11 powder contains one or more metaatoms embedded in each powder particle. For example, one powder particle of metamaterial 11 may contain multiple metaatoms.

[0024] Figure 2 shows an example of the coating of the present disclosure. The coating 13 of the present disclosure has powdered metamaterial 11 added to the solvent 12. The powder of the metamaterial 11 is covered with a resin that does not dissolve in the solvent 12, and therefore has the property of not bonding with each other.

[0025] Either an aqueous or oil-based solvent 12 can be used as the solvent. Therefore, any material capable of functioning as a paint 13 can be used as the solvent 12. For example, paint used on building materials can be used as the solvent 12. In this form, the functionality of the metamaterial 11 can be added to the durability, coloring effect, gloss, waterproofing, and stain resistance of the paint used on building materials. For example, the solvent 12 for indoor paint 13 may include at least one of acrylic and silicone used for interior finishes. The solvent 12 for outdoor paint 13 may include at least one of acrylic, urethane, silicone, fluorine, and enamel used for exterior finishes. The solvent 12 for glass paint 13 may include at least one of acrylic and silicone.

[0026] In this way, by combining the solvent 12 with the solute metamaterial 11 powder, it is possible to apply the mixture to various media such as glass and building materials.

[0027] The color of the metamaterial 11 powder itself can be colored to any desired color by changing the resin covering the metaatom. Therefore, if the color of the metamaterial 11 powder and the color of the solvent 12 are the same, the paint 13 of this disclosure can add the function of the metamaterial 11 powder without impairing the color of the coating liquid used as the solvent 12. Furthermore, if the metamaterial 11 powder is made spherical by heating or other means, changes in the texture of the coating liquid used as the solvent 12 can also be suppressed.

[0028] In this disclosure, the powder of the metamaterial 11 is added to the solvent 12. As a result, as shown in Figure 3, a new function using the metamaterial 11 can be added to the object 91 simply by applying the formed coating 13 to the object 91.

[0029] When the metamaterial 11 is added to the solvent 12, it is less likely to become uneven or separate within the paint 13, and the direction of the metaatoms becomes random. Therefore, when the paint 13 of this disclosure is applied to an object 91, a coating film is formed on the surface of the object 91 in which the metamaterial 11 is spread uniformly, as shown in Figure 3. As a result, the function of the metamaterial 11 can be obtained evenly in the area of ​​the coating film to which the paint 13 is applied.

[0030] Figure 4 shows an example of the coating state when paint 13 is applied to an object 91. The state of the metamaterial 11 powder was observed when the paint, which uses cubic COC blocks with sides of 200 μm as the metamaterial powder, was sprayed onto the object 91 and when it was brush-applied. Figure 4A is a 50x magnification image of the coating film formed by applying only solvent 12, Figure 4B is a 50x magnification image of the coating film formed by spraying paint 13, Figure 4C is a 50x magnification image of the coating film formed by brush-applying paint 13, Figure 4D is a 200x magnification image of the coating film formed by applying only solvent 12, Figure 4E is a 200x magnification image of the coating film formed by spraying, and Figure 4F is a 200x magnification image of the coating film formed by brush-applying paint 13. In both the spray and brush application methods of the paint 13 of this embodiment, it can be confirmed that the powder of the metamaterial 11 is three-dimensionally embedded and attached within the paint film.

[0031] The method of applying the paint 13 to the object 91 is arbitrary. For example, it may be applied by spraying, brushing, or roller application. Although Figure 3 shows an example of a coating film with one layer of paint 13, there may be multiple layers of paint 13 forming the coating film. The functions of the metamaterial 11 powder contained in the multiple layers of paint 13 forming the coating film may be the same or different. In this way, by layering multiple layers of paint 13 on the coating film, it is possible to combine functions and adjust the characteristics that can be added.

[0032] By employing the coating 13 of this embodiment, the metamaterial 11 powder can be easily applied to curved surfaces and objects with complex shapes. This overcomes the conventional problem of needing to prepare films or the like tailored to the object to be coated, as coating allows for the formation of a coating layer containing the metamaterial regardless of its shape. In this embodiment, it is also possible to arrange the metamaterial 11 powder three-dimensionally, thereby realizing a three-dimensional bulk metamaterial. As a result, polarization dependence and incident angle dependence can be eliminated, and isotropic optical properties can be achieved.

[0033] To achieve ultra-high-speed wireless communication in sixth-generation mobile communication systems (6G), a large receiving output is required, and this necessitates a focused beam, interference prevention, and radio wave reflectors. By adopting the paint 13 of this disclosure, a three-dimensional bulk metamaterial can be realized, making it possible to respond to radio waves with various directivity.

[0034] (Second Embodiment) In this embodiment, a method for applying the paint 13 will be described. In this embodiment, the paint 13 is sprayed onto the surface of an object 91 using the spraying device of the present disclosure. Figure 5 shows an example of the configuration of the nozzle portion of the spraying device 20 of this embodiment.

[0035] In this embodiment, the spraying device 20 has a container 21 that holds paint 13, which is surrounded by a housing 24 at a distance. An internal nozzle 22 is formed at the tapered tip of the container 21 in the direction of spraying. A flow path is formed between the container 21 and the housing 24 through which compressed air can be supplied. When the paint 13 in the container 21 is pushed towards the internal nozzle 22, the compressed air supplied between the container 21 and the housing 24 mixes with the paint 13 pushed out from the internal nozzle 22, and together with the compressed air, the paint 13 is sprayed as a mist to the outside of the housing 24 from the external nozzle 25 of the housing 24.

[0036] Inside the container 21, there is a needle valve 23 that moves in conjunction with compressed air flowing between the container 21 and the housing 24. By adjusting the amount of movement of this needle valve 23, the gap between the internal injection port 22 and the needle valve 23 can be adjusted.

[0037] Inner diameter D of the inner injection port 22 ２２ and outer diameter D of the outer injection port 25 ２５ can adopt arbitrary values according to the diameter of the powder of the metamaterial 11. For example, when the diameter of the powder of the metamaterial 11 is 200 μm, the inner diameter D ２２ and the outer diameter D ２５ can be about 400 μm. The inner diameter D ２２ and the outer diameter D ２５ is not limited to twice the diameter of the powder of the metamaterial 11. For example, when the diameter of the powder of the metamaterial 11 is 40 μm, the inner diameter D ２２ and the outer diameter D ２５ can be about 150 μm, or when the diameter of the powder of the metamaterial 11 is 500 μm, the inner diameter D ２２ and the outer diameter D ２５ can be about 700 μm. Note that the inner diameter D ２２ and the outer diameter D ２５ may be different. In that case, the inner diameter D ２２ may be smaller than the outer diameter D ２５ .

[0038] Fig. 6 shows another form of the nozzle portion of the spraying device 20 of the present embodiment. Compression layers 31 and 32 for diverting the compressed air between the container 21 and the housing 24 are provided between the container 21 and the housing 24. As shown in Fig. 6, the shape of the paint 13 after ejection can be changed by the shape of the outer injection port 25, the mixing of the compressed air into the ejected paint 13, and the spraying method.

[0039] The spraying device of the present embodiment can spray the paint 13 onto the object 91 by spraying. Therefore, various functions according to the metamaterial 11 such as radio wave interference prevention and reflection function can be provided even for complex shapes.

[0040] As described above, it can be seen that by applying the paint 13 of the present disclosure to the object 91, transmittance, refractive index, and phase similar to those of the COC sheet can be obtained. Therefore, the paint 13 of the present disclosure can easily mount any function realizable by the metamaterial 11 on objects with curved surfaces and complex shapes.

[0041] 11: Metamaterial powder 12: Solvent 13: Paint 20: Spraying device 21: Container 22: Internal nozzle 23: Needle valve 24: Housing 25: External nozzle 31, 32: Compression layer 91: Object

Claims

1. A paint comprising: a solvent having any color; and a powdery metamaterial added to the solvent, wherein metaatoms are covered with a resin.

2. The paint according to claim 1, wherein the color of the resin of the metamaterial is the same as the color of the solvent.

3. A spraying device for spraying the paint described in claim 1 or 2.

4. A method of applying paint according to claim 1 or 2 by spraying it onto the surface of an object.

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