Coating film laminate, inspection method, and inspection device

Abstract

A coating film laminate (10) comprises: a scattering coating material (15) (first coating material) for scattering electromagnetic waves in a specific band; and an absorbing coating material (16) (second coating material) for absorbing electromagnetic waves in the specific band, and is disposed on the surface of an outdoor structure (11). The coating film laminate (10) is capable of inspecting coating deterioration on the basis of a predetermined pattern included in an image obtained by capturing reflected microwaves from microwaves emitted from a satellite (20).

Description

Coating laminate, inspection method and inspection device

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to paint stacks, inspection methods and inspection devices.

[0002] Painted steel roofs and outdoor structures such as bridges deteriorate in stages. For example, in the case of steel roofs, deterioration progresses in the following order: (1) change and wear of the coating, (2) zinc wear, and (3) corrosion of the steel base. Because characteristic changes in appearance are observed at each stage, steel roofs must be regularly monitored for any changes. If these changes in appearance are left unchecked, rainwater may penetrate the roof, causing leaks and damaging the interior of the building. Therefore, what would have been achieved by simply repainting the roof may require significant costs, such as re-roofing or building renovations. Therefore, to prevent deterioration of the coating on painted steel, it is necessary to regularly monitor for changes and make repairs as necessary.

[0003] In the past, outdoor structures were generally inspected visually by workers. However, as outdoor structures continue to grow taller and larger, there is also a growing social demand for efficiency to address labor shortages and other issues. For this reason, inspection methods using drones have been established in recent years (see, for example, Non-Patent Document 1).

[0004] “Technology Research Trends: Complete roof inspections with just a few taps! Drone-based roof inspection system “HACHIDORI (registered trademark),” [online], Daiwa House Industry Co., Ltd., [searched August 13, 2024], Internet <URL: https: / / www.daiwahouse.co.jp / lab / column / detail / 05 / >

[0005] However, whether the inspection is performed visually by a worker or using a drone, the worker or drone operator must go to the site where the outdoor structure to be inspected is located.

[0006] On the other hand, inspection using satellite images is one method of inspecting the paint on outdoor structures without visiting the site. However, inspection using observation satellites has the following issues:

[0007] First, when using optical satellites, it is not easy to properly detect the deterioration state based on the rust color because the colors of structure roofs vary widely. Also, because it is necessary to capture changes in color tone, it is not possible to detect the deterioration of the paint until rust has occurred. In other words, the method using optical satellites has the problem of not being able to detect paint deterioration early enough to allow repainting.

[0008] Next, inspections can be performed using synthetic aperture radar (SAR) satellites. For example, radar images of the inspection target can be observed, and polarization decomposition techniques can be used to detect the absorption of electromagnetic waves when rust forms. However, this method can only detect rust after it has formed, and cannot prevent corrosion before it occurs. Furthermore, detecting corrosion requires comparing observation results over time, which requires managing radar images in a database.

[0009] It is also possible to detect displacement of the painted surface of outdoor structures by using interferometric SAR time series analysis. However, the thickness of the paint film on outdoor structures such as roofs is approximately 0.06 mm to 0.1 mm, and it is difficult to detect the disappearance of paint film of this thickness using SAR.

[0010] Therefore, the object of the present disclosure, which has been made with these points in mind, is to provide a coating film laminate, an inspection method, and an inspection device that enable the paint condition of outdoor structures to be inspected without going to the site.

[0011] A coating laminate according to one embodiment comprises a first coating material that scatters electromagnetic waves in a specific band and a second coating material that absorbs electromagnetic waves in the specific band, and is placed on the surface of an outdoor structure.

[0012] An inspection method according to one embodiment is a method for inspecting deterioration of a paint film laminate used in painting an outdoor structure, the paint film laminate including a first paint that scatters electromagnetic waves in a specific band and a second paint that absorbs electromagnetic waves in the specific band, and includes irradiating electromagnetic waves in the specific band from above onto an area including the outdoor structure, obtaining an image of the reflected electromagnetic waves, correlating a position on a map of the area including the outdoor structure with a position on the image, detecting a predetermined pattern from the image, and determining whether the pattern has been detected at a position on the image that corresponds to the position of the outdoor structure on the map.

[0013] An inspection device according to one embodiment is an inspection device used to inspect deterioration of a paint film laminate used in painting outdoor structures, the paint film laminate including a first paint that scatters electromagnetic waves in a specific band and a second paint that absorbs electromagnetic waves in the specific band, and is placed on the surface of an outdoor structure. The inspection device is equipped with an acquisition unit that irradiates electromagnetic waves in the specific band from above onto an area including the outdoor structure and acquires an image of the reflected electromagnetic waves, and a control unit that is capable of performing processing to associate a position on a map of the area including the outdoor structure with a position on the image, detect a predetermined pattern from the image, and determine whether the pattern has been detected at a position on the image that corresponds to the position of the outdoor structure on the map.

[0014] According to the present disclosure, a paint film laminate placed on the surface of an outdoor structure is irradiated from above with electromagnetic waves of a specific band, and paint deterioration is inspected based on a predetermined pattern contained in an image captured of the reflected electromagnetic waves, making it possible to inspect the paint condition of an outdoor structure without going to the site.

[0015] FIG. 1 is a cross-sectional view showing an example of a paint film laminate according to an embodiment. FIG. 2 is a view showing an example of a pattern formed on the intermediate coat layer of FIG. 1. FIG. 3 is a view showing an example of a pattern formed on the intermediate coat layer of FIG. 1. FIG. 4 is a view showing an example of a pattern formed on the intermediate coat layer of FIG. 1. FIG. 5 is a view explaining an example of the configuration of a scattering paint (first paint). FIG. 6 is a view showing a schematic configuration of an inspection system 1 that detects paint deterioration. FIG. 7 is a block diagram showing a schematic configuration of the inspection device of FIG. 4. FIG. 8 is a flowchart showing an example of processing executed by a control unit of the inspection device of FIG. 4. FIG. 9 is a view showing an example of a top coat layer (first layer) when the paint film laminate is applied to a railway bridge. FIG. 10 is a view showing an example of an intermediate coat layer (second layer) when the paint film laminate is applied to a railway bridge.

[0016] This disclosure proposes a method for identifying the pattern from above using a satellite or other device when the outer coating of an outdoor structure deteriorates by providing a layer in the coating with electromagnetic wave scattering and absorption properties. This method makes it possible to inspect the deterioration of the coating of an outdoor structure from images taken by a satellite or other device, without the need for workers to go to the site.

[0017] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0018] (Coating Laminate) FIG. 1 shows a cross-sectional view of a coating laminate 10 according to one embodiment of the present disclosure. The coating laminate 10 has a structure in which a primer layer 12, an intermediate coat layer 13, and a top coat layer 14 are laminated on an outdoor structure 11, such as a roof, in this order from the outdoor structure 11 side. The top coat layer 14 is the first layer located on the outermost surface. The intermediate coat layer 13 is the second layer located on the outdoor structure side of the top coat layer 14. The coating laminate 10 is not limited to a three-layer structure and may further include other layers. For example, the coating laminate 10 has a total thickness of 0.06 mm to 0.1 mm including the primer layer 12, intermediate coat layer 13, and top coat layer 14. However, the thickness of the coating laminate 10 is not limited to this range.

[0019] The outdoor structure 11, which is a roof, is made of a metal material such as galvalume or galvanized iron. Metal roofs tend to rust when the coating deteriorates. Slate roofs, which are made by molding cement and fiber materials, are sometimes used as roofing materials. Slate roofs can develop cracks when the coating deteriorates. The coating laminate 10 serves to protect the surface of the outdoor structure 11.

[0020] The primer layer 12 is made of a resin material such as an acrylic resin, a urethane resin, or an epoxy resin, and functions as a sealer that is applied directly to the surface of the outdoor structure 11. The primer layer 12 increases the adhesion between the painted surface of the outdoor structure 11 and the intermediate coat layer 13 and top coat layer 14, thereby preventing the coating laminate 10 from peeling off from the painted surface.

[0021] The intermediate coating layer 13 is located on top of the primer layer 12. As shown in Figures 2A to 2D, a predetermined pattern is formed on the intermediate coating layer 13 using a scattering paint 15 and an absorbing paint 16. The scattering paint 15 is the first paint, and the absorbing paint 16 is the second paint.

[0022] The scattering paint 15 is a paint that has the property of scattering electromagnetic waves in a specific band. The specific band is, for example, the microwave band observable by SAR (Synthetic Aperture Radar) satellites. Microwaves are electromagnetic waves with a frequency range of approximately 3 GHz to 30 GHz. Electromagnetic waves with a frequency range of approximately 300 MHz to 30 GHz are also sometimes called microwaves. As shown in FIG. 3 , the scattering paint 15 is, for example, a urethane-based, silicone-based, fluororesin-based, or acrylic-based paint to which flake-shaped pieces 19 made of metal 17 coated with glass 18 have been added. The scattering paint 15 may also be a paint to which minute particles or foil of a corrosion-resistant metal such as gold, platinum, or stainless steel have been added, or a paint to which minute ceramic particles have been added.

[0023] The absorbent paint 16 is a paint that has the property of absorbing electromagnetic waves in the specific band. The absorbent paint 16 is formed, for example, by mixing a urethane-based, silicone-based, fluororesin-based, or acrylic-based paint with a rust-resistant conductive filler that absorbs electromagnetic waves. For example, the absorbent paint 16 may be a paint to which carbon fiber or metal oxide is added as a conductive filler. Alternatively, the absorbent paint 16 may be a water-based paint containing single-walled carbon nanotubes (SGCNTs) synthesized by the super-growth method. Alternatively, a carbon nanotube (CNT) electromagnetic wave suppression sheet may be used in the intermediate coating layer 13 instead of the absorbent paint 16.

[0024] The predetermined pattern of the intermediate coating layer 13 may be an artificial pattern not found in nature, or a pattern consisting of straight lines and / or curves with distinctive contrast. Furthermore, in order to address partial paint deterioration, it is preferable to adopt a pattern that can be formed as a figure even in a small area. Furthermore, it is preferable for the predetermined pattern to be recognizable even in satellite images with low resolution. The predetermined pattern can be observed as a pattern with a constant aspect ratio, assuming observation from a sun-synchronous quasi-recurrent orbit satellite. Since sun-synchronous quasi-recurrent orbit satellites fly over the same location at the same time, the sunlight conditions when observing the pattern are stable, making it easier to capture the intended shape.

[0025] In Figures 2A and 2B, the pattern of the intermediate coating layer 13 is formed by alternately arranging rectangular regions of scattering paint 15 and absorbent paint 16 in two orthogonal directions. The rectangles may be squares or rectangles with a specific aspect ratio. The rectangles may have an aspect ratio that results in a square when observed obliquely by a satellite. In Figure 2C, the pattern includes a rectangular region of scattering paint 15, a region of absorbent paint 16 surrounding the scattering paint 15 in a rectangular shape, and a region of scattering paint 15 surrounding the absorbent paint 16 in a rectangular shape. In Figure 2D, the pattern includes four rectangular regions of absorbent paint 16 arranged in two rows and two columns within the rectangular region of scattering paint 15. The predetermined patterns shown in Figures 2A to 2D may be two-dimensionally repeated in a direction along the surface of the outdoor structure 11. The predetermined patterns shown in Figures 2A to 2D are merely examples, and various other patterns may be employed.

[0026] The topcoat layer 14 is a coating layer made of a coating material that scatters electromagnetic waves in a specific band. The topcoat layer 14 may contain the same scattering coating material 15 as the intermediate coating layer 13, or may contain a different type of scattering coating material from the scattering coating material 15 of the intermediate coating layer 13. Unlike the intermediate coating layer 13, the topcoat layer 14 does not contain an absorbent coating material 16. The topcoat layer 14 is formed as a uniform coating layer that does not contain any pattern. The topcoat layer 14 is the first layer in the coating laminate 10 to disappear due to deterioration.

[0027] The pattern formed by the scattering paint 15 and the absorbing paint 16 of the intermediate coat 13 can be recognized by a satellite passing overhead when the top coat 14 deteriorates and disappears.

[0028] (Image Acquisition of Paint Laminate Using Satellite) Next, a system 1 for inspecting a paint laminate 10 on an outdoor structure 11 using a satellite 20 will be described with reference to Fig. 4. The system 1 includes the satellite 20, a base station 26, and an inspection device 30.

[0029] The satellite 20 is equipped with an active microwave sensor including a microwave transceiver. Microwaves in bands such as L-band (1-2 GHz), C-band (4-8 GHz), and X-band (8-12 GHz) are used to observe the Earth's surface using microwaves. However, the electromagnetic wave bands used by the satellite 20 for observation are not limited to these. The microwave sensor irradiates microwaves obliquely toward the Earth's surface and detects backscattered waves from the Earth's surface. The satellite 20 is, for example, an SAR satellite. The satellite 20 in orbit irradiates microwaves 21 toward an area including an outdoor structure 11 located on the ground. A portion of the scattered microwaves 22 scattered by the surface of the coating film laminate 10 on the outdoor structure 11 travels toward the satellite 20 and is observed by the satellite 20. On the other hand, if the microwaves irradiated by the satellite 20 are absorbed or specularly reflected, the electromagnetic waves are not detected by the satellite 20, and the surface of the outdoor structure 11 is not observed by the satellite 20 or is observed as a dark area on the image.

[0030] For example, when the paint film laminate 10 is not deteriorated, the top coat layer 14 is located on the outermost surface. The top coat layer 14 contains a scattering paint 15 that scatters electromagnetic waves, and therefore the microwaves 21 irradiated from the satellite 20 are scattered by the top coat layer 14. For this reason, the paint film laminate 10 on the outdoor structure 11 is observed on the satellite image as a uniformly bright area without any pattern.

[0031] On the other hand, when the coating film laminate 10 deteriorates and the top coat layer 14 disappears, the intermediate coat layer 13 is exposed on the surface. The portion of the intermediate coat layer 13 where the scattering paint 15 is exposed on the surface scatters microwaves irradiated from the satellite 20 in the same manner as the top coat layer 14, and a portion of the scattered waves 22 is observed by the satellite 20. Microwaves 21 incident on the portion of the intermediate coat layer 13 where the absorbent paint 16 is exposed on the surface are absorbed by the absorbent paint 16, and the scattered waves 22 from this portion are not observed by the satellite 20. Therefore, by observing the scattered waves 22 of the microwaves 21 irradiated from the satellite 20, it is possible to obtain an image including patterns formed by the scattering paint 15 and the absorbent paint 16, as shown in Figures 2A to 2D. In the satellite image observed by the satellite 20, the exposed areas of the scattering paint 15 appear as bright areas, and the exposed areas of the absorbent paint 16 appear as dark areas.

[0032] The satellite 20 may be a sun-synchronous quasi-recurrent orbit satellite. A sun-synchronous quasi-recurrent orbit is an orbit that combines a sun-synchronous orbit and a quasi-recurrent orbit. A sun-synchronous orbit is an orbit in which the positional relationship between the satellite and the sun is always constant and the solar conditions are the same. A quasi-recurrent orbit is an orbit in which the satellite flies over the same point at the same time at a regular interval. By observing from a sun-synchronous quasi-recurrent orbit, the sunlight conditions are stable and the satellite flies over the same point at the same time, so the pattern of the intermediate coating layer 13 is observed in the satellite image in the expected shape. When observed from an orbit that does not pass over the same point, the pattern included in the satellite image may tilt depending on the observation direction, and the expected shape may not be recognized.

[0033] The satellite 20 irradiates the earth's surface with microwaves and transmits an image signal 25 observed to an antenna 27 of a terrestrial base station 26. The image signal 25 may be transmitted from the satellite 20 to the base station 26 via another satellite such as a communication satellite. The base station 26 transmits the received image signal 25 to the inspection device 30. The inspection device 30 determines whether or not there is deterioration in the paint of the target outdoor structure based on the image signal 25 obtained from the satellite. The base station 26 and the inspection device 30 may be connected by any communication means.

[0034] (Inspection Device) The inspection device 30 is an information processing device that analyzes images acquired from the satellite 20. As shown in FIG. 5 , the inspection device 30 includes a satellite image acquisition unit 31, a control unit 32, a storage unit 33, and an input / output unit 34. The inspection device 30 of the present disclosure can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network. The computer includes a PC (Personal Computer), a workstation, and other general-purpose or dedicated computers.

[0035] The satellite image acquisition unit 31 includes at least one external communication interface for communicating with the base station 26 of the satellite 20. The satellite image acquisition unit 31 can also be referred to as a communication unit. The communication interface may be either a wired communication interface or a wireless communication interface. In the case of wired communication, the communication interface is, for example, a local area network (LAN) interface or a universal serial bus (USB). In the case of wireless communication, the communication interface is, for example, an interface compatible with a mobile communication standard such as long term evolution (LTE), fourth generation (4G), or fifth generation (5G).

[0036] The control unit 32 includes at least one processor, at least one dedicated circuit, or a combination thereof. The processor is a general-purpose processor such as a central processing unit (CPU) or a graphics processing unit (GPU), or a dedicated processor specialized for a specific process. The dedicated circuit is, for example, a field-programmable gate array (FPGA) or an application specific integrated circuit (ASIC). The control unit 32 executes processes related to the operation of the inspection device 30 while controlling each part of the inspection device 30. The processes executed by the control unit 32 can be considered as processes executed by the inspection device 30.

[0037] The storage unit 33 includes at least one semiconductor memory, at least one magnetic memory, at least one optical memory, or a combination of at least two of these. The semiconductor memory is, for example, a random access memory (RAM) or a read-only memory (ROM). The RAM is, for example, a static random access memory (SRAM) or a dynamic random access memory (DRAM). The ROM is, for example, an electrically erasable programmable read-only memory (EEPROM). The storage unit 33 functions as, for example, a main storage device, an auxiliary storage device, or a cache memory. The storage unit 33 stores programs and data used in the operation of the inspection device 30, and data obtained by the operation of the inspection device 30.

[0038] The storage unit 33 stores map information of an area including the outdoor structure 11 to be inspected. The inspection device 30 may be configured to be able to acquire map information from outside the inspection device 30 as needed. The map information may include location information such as latitude and longitude of each position on the map. The map information may include information on the shape of the upper surface of the roof or the like of the outdoor structure 11 to be inspected. The storage unit 33 can further store satellite images acquired by the satellite 20 and transmitted to the inspection device 30, images obtained by image processing the satellite images, and / or location information of patterns included in the satellite images.

[0039] The input / output unit 34 may include an input device through which a user of the inspection device 30 inputs instructions and information, and an output device that presents information to the user. The input device may include a keyboard, a mouse, a camera, etc. The output device may include a display, a speaker, a printer, etc. The display may be, for example, a liquid crystal display (LCD), an organic electroluminescence (EL) display, or an inorganic EL display. The input / output unit 34 may include a touch panel that detects input by touching the surface of the display.

[0040] The input / output unit 34 may receive input of information such as the position, size, and shape of the outdoor structure 11 to be inspected from an operator who operates the inspection device 30. The input / output unit 34 may display map information stored in the storage unit 33 and receive designation of the outdoor structure 11 to be inspected on the map from the operator. The input / output unit 34 may accept an operation from the operator and display the inspection results of the outdoor structure 11 to be inspected to the operator.

[0041] The functions of the inspection device 30 are realized by executing a program relating to the inspection method of this embodiment in a processor corresponding to the control unit 32. That is, the functions of the inspection device 30 are realized by software. The program causes a computer to execute the operations of the inspection device 30, thereby causing the computer to function as the inspection device 30. That is, the computer functions as the inspection device 30 by executing the operations of the inspection device 30 in accordance with the program.

[0042] In this embodiment, the program can be recorded on a computer-readable recording medium. The computer-readable recording medium includes non-transitory computer-readable media, such as a magnetic recording device, an optical disc, a magneto-optical recording medium, or a semiconductor memory. The program can be distributed, for example, by selling, transferring, or lending a portable recording medium, such as a DVD (digital versatile disc) or a CD-ROM (compact disc read only memory), on which the program is recorded. The program can also be distributed by storing the program in the storage of an external server and transmitting the program from the external server to another computer. The program can also be provided as a program product.

[0043] (Inspection Method) Next, an inspection method executed by the control unit 32 of the inspection device 30 will be described with reference to FIG.

[0044] The satellite image acquisition unit 31 acquires, via the base station 26, a satellite image of an area including the outdoor structure 11 to be inspected, which has been imaged by the satellite 20 (step S101). The inspection device 30 may acquire satellite images of all or part of the area imaged by the satellite 20. The operator of the inspection device 30 may input in advance to the inspection device 30 via the input / output unit 34 the area of ​​the detection target for which the inspection device 30 will acquire satellite images. The inspection device 30 may be configured to transmit, via the satellite image acquisition unit 31, the area of ​​the detection target for which satellite images will be acquired in advance to the base station 26, and acquire a satellite image of the area of ​​the detection target from the base station 26.

[0045] The control unit 32 associates the satellite image acquired by the satellite image acquisition unit 31 with the map image stored in the storage unit 33 (step S102). The control unit 32 can associate each position on the satellite image with the coordinates of the position on the map indicated by the map information. For example, the control unit 32 can acquire information about the surface condition of the observation target by using a polarization decomposition method on the satellite image of the SAR satellite. Examples of polarization decomposition methods include Pauli decomposition, three-component scattering decomposition, and four-component scattering decomposition. The polarization decomposition method improves the accuracy of identifying artificial structures and natural objects included in the satellite image, making it easier to combine the satellite image with the map image.

[0046] The control unit 32 detects a predetermined pattern from the satellite image by image analysis (step S103). The predetermined pattern is, for example, the pattern shown in Figures 2A to 2D. At the location where the predetermined pattern can be detected, at least a portion of the top coat layer 14 of the coating film laminate 10 of the outdoor structure 11 has disappeared due to deterioration. Even if a portion of the pattern is missing, the control unit 32 can extract the characteristics of the pattern from the remaining portion of the pattern. Therefore, the control unit 32 can detect the predetermined pattern on the surface of the same outdoor structure 11 in both a state where the top coat layer 14 has partially disappeared and a portion of the intermediate coat layer 13 has been exposed, and a state where a portion of the intermediate coat layer 13 has been exposed and another portion of the intermediate coat layer 13 has been lost.

[0047] The control unit 32 stores the position information of the position on the map where the pattern was detected in the storage unit 33 (step S104). The control unit 32 may store the information of the position where the pattern was detected in the storage unit 33 together with the information of the satellite image.

[0048] The control unit 32 determines whether a predetermined pattern is detected at the position of the outdoor structure 11 to be inspected (step S105). If a pattern is detected at the position of the outdoor structure 11 to be inspected, it can be determined that deterioration has occurred in the paint of the outdoor structure 11. This allows the control unit 32 to extract outdoor structures 11 whose paint has deteriorated and which require repair.

[0049] Based on the determination result of step S105, the control unit 32 stores the inspection result in the storage unit 33 and / or outputs the inspection result to the input / output unit 34 (step S106). The control unit 32 may output information such as the state of deterioration and / or the need for repair of the outdoor structure 11 to be inspected, for example, in a table format or by displaying it on map information.

[0050] As described above, the paint film laminate, inspection method, and inspection device according to this embodiment use satellite images taken by a satellite 20 that can overlook the ground from above, allowing workers or the like to inspect the state of deterioration of the painted surface without having to go to the location of the outdoor structure to be inspected.

[0051] Furthermore, in this embodiment, a SAR satellite that uses microwaves for observation is used to observe the pattern formed by the arrangement of the scattering paint 15 and the absorbent paint 16 of the intermediate coat layer 13. This allows the inspection device 30 of the present disclosure to detect paint deterioration at an early stage when at least a portion of the top coat layer 14 has disappeared. This makes it possible to grasp paint deterioration before the paint film disappears further, exposing the metal structure that makes up the outdoor structure 11 and causing rust to form on the surface.

[0052] Furthermore, the inspection device 30 of this embodiment can determine that deterioration of the painted surface has occurred by observing a predetermined pattern. Therefore, the inspection device 30 does not need to store image data of the painted surface of the outdoor structure 11 being inspected in chronological order in the storage unit 33 for comparison with past images. Therefore, the inspection device 30 has the advantage of not needing to store a large amount of image data.

[0053] In addition, in this embodiment, by using a sun-synchronous quasi-recurrent orbit satellite as the satellite 20, the pattern of the intermediate coat layer 13 of the paint film laminate 10 can be observed from a stable position and angle direction during a stable time period. This stabilizes the shape of the pattern included in the satellite image, allowing the inspection device 30 to accurately detect the pattern on the painted surface of the outdoor structure 11.

[0054] In the above embodiment, the coating film laminate 10 is applied to the roof of a building or the like as the outdoor structure 11. However, the outdoor structure 11 may also be a metal frame such as a steel bridge or steel tower. For example, when the outdoor structure 11 is a steel bridge 40, as shown in FIGS. 7A and 7B , a scattering paint 15 may be used for the top coat layer 14, which is the outermost surface, and the scattering paint 15 and the absorbent paint 16 may be alternately arranged in the intermediate coat layer 13 along the extension direction of the metal frame. When the paint on the steel bridge 40 has deteriorated and part of the intermediate coat layer 13 is exposed, the inspection device 30 can acquire satellite images including a striped pattern of the scattering paint 15 and the absorbent paint 16 from the satellite images. Note that the pattern of the intermediate coat layer 13 of a metal frame such as a steel bridge or steel tower is not limited to that shown in FIG. 7B , and various patterns are possible.

[0055] Although the above-described embodiments have been described as typical examples, it will be apparent to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and / or alterations are possible without departing from the scope of the claims. For example, multiple building blocks described in the embodiments and examples can be combined into one, or one building block can be divided.

[0056] In the above embodiment, the coating laminate 10 was observed using a satellite. However, the coating laminate 10 can also be observed from an aircraft flying above the coating laminate 10 using a synthetic aperture radar mounted on the aircraft. Furthermore, in the above embodiment, the electromagnetic waves in the specific band are microwaves. However, the electromagnetic waves in the specific band are not limited to microwaves and may be, for example, electromagnetic waves in the millimeter wave band (frequency 30 to 300 GHz).

[0057] In the above embodiment, the scattering paint 15 is used for the top coat layer 14, which is the first layer. However, it is also possible to use a uniform absorbent paint 16 for the top coat layer 14. In this case, if there is no deterioration of the paint on the top coat layer 14, the irradiated electromagnetic waves are absorbed, and the coating film laminate 10 of the outdoor structure 11 is not observed from the satellite 20. On the other hand, if the top coat layer 14 deteriorates and disappears, a predetermined pattern is observed due to scattering by the scattering paint 15 of the intermediate coat layer 13. It is also possible to form different patterns on both the intermediate coat layer 13 and the top coat layer 14 by using the scattering paint 15 and the absorbent paint 16. For example, the intermediate coat layer 13 and the top coat layer 14 can be made to have striped patterns that are 90 degrees apart, and the areas where the direction of the stripes changes can be determined to be areas where the top coat layer 14 is deteriorated.

[0058] The following additional notes are provided regarding the above-described embodiments.

[0059] (Supplementary Item 1) A coating film laminate to be placed on the surface of an outdoor structure, comprising a first coating material that scatters electromagnetic waves in a specific band, and a second coating material that absorbs electromagnetic waves in the specific band. (Supplementary Item 2) The coating film laminate according to Supplementary Item 1, wherein the first coating material is a coating material containing small pieces of glass-coated metal, a coating material containing fine particles or foil of gold, platinum, or stainless steel, or a coating material containing fine ceramic particles. (Supplementary Item 3) The coating film laminate according to Supplementary Item 1 or 2, wherein the second coating material is a coating material containing carbon fiber or metal oxide as a conductive filler, or a single-walled carbon nanotube-based water-based coating material. (Supplementary Item 4) The coating laminate according to any one of Supplementary Items 1 to 3, comprising a first layer located on the outermost surface and a second layer located on the outdoor structure side of the first layer, wherein the first layer scatters electromagnetic waves in the specific band, and a predetermined pattern is formed on the second layer using the first paint and the second paint, and when the second layer is exposed due to deterioration of the first layer, the pattern can be observed using a sensor that irradiates electromagnetic waves in the specific band from above and detects scattered waves of the electromagnetic waves. (Supplementary Item 5) The coating laminate according to Supplementary Item 4, wherein the electromagnetic waves in the specific band are microwaves, and the sensor is a microwave sensor mounted on a satellite. (Supplementary Item 6) The coating laminate according to Supplementary Item 5, wherein the satellite is a sun-synchronous subrecurrent orbit satellite, and the pattern is configured to be observed by the satellite as a pattern with a constant aspect ratio. (Appendix 7) An inspection method for inspecting deterioration of a paint film laminate used in painting an outdoor structure, the paint film laminate including a first paint that scatters electromagnetic waves in a specific band and a second paint that absorbs electromagnetic waves in the specific band, the inspection method including: irradiating an area including the outdoor structure with electromagnetic waves in the specific band from above, and acquiring an image capturing the reflected electromagnetic waves; correlating a position on a map of the area including the outdoor structure with a position on the image; detecting a predetermined pattern from the image; and determining whether or not the pattern has been detected at a position on the image that corresponds to the position of the outdoor structure on the map.(Addendum 8) An inspection device used to inspect deterioration of a paint film laminate used in painting an outdoor structure, the paint film laminate including a first paint that scatters electromagnetic waves in a specific band and a second paint that absorbs electromagnetic waves in the specific band, and the inspection device is arranged on the surface of an outdoor structure, the inspection device comprising: an acquisition unit that irradiates electromagnetic waves in the specific band from above onto an area including the outdoor structure and acquires an image of the reflected electromagnetic waves; and a control unit that is capable of performing a process of associating a position on a map of the area including the outdoor structure with a position on the image, detecting a predetermined pattern from the image, and determining whether the pattern has been detected at a position on the image that corresponds to the position of the outdoor structure on the map.

[0060] REFERENCE SIGNS LIST 1 Inspection system 10 Paint film laminate 11 Outdoor structure 12 Primer layer 13 Intermediate coat layer (second layer) 14 Top coat layer (first layer) 15 Scattering paint (first paint) 16 Absorbent paint (second paint) 17 Metal 18 Glass 19 Small piece 20 Satellite 21 Microwave 22 Scattered wave 25 Image signal 27 Antenna 30 Inspection device 31 Satellite image acquisition unit 32 Control unit 33 Memory unit 34 Input / output unit 40 Railway bridge

Claims

1. A coating laminate to be placed on the surface of an outdoor structure, comprising a first coating material that scatters electromagnetic waves in a specific band and a second coating material that absorbs electromagnetic waves in the same specific band.

2. The coating laminate of claim 1, wherein the first coating is a coating containing small pieces of glass-coated metal, a coating containing minute particles or foils of gold, platinum, or stainless steel, or a coating containing minute ceramic particles.

3. A coating film laminate according to claim 1 or 2, wherein the second coating material is a coating material containing carbon fiber or metal oxide as a conductive filler, or a single-walled carbon nanotube-based water-based coating material.

4. A coating film laminate described in any one of claims 1 to 3, characterized in that it comprises a first layer located on the outermost surface and a second layer located on the outdoor structure side of the first layer, wherein the first layer scatters electromagnetic waves in the specific band, and a predetermined pattern is formed on the second layer using the first paint and the second paint, and when the second layer is exposed due to deterioration of the first layer, the pattern can be observed using a sensor that irradiates electromagnetic waves in the specific band from above and detects the scattered waves of the electromagnetic waves.

5. The coating laminate according to claim 4, wherein the electromagnetic waves in the specific band are microwaves, and the sensor is a microwave sensor mounted on a satellite.

6. The coating laminate of claim 5, wherein the satellite is a sun-synchronous subrecurrent orbit satellite, and the pattern is configured to be observed by the satellite as having a constant aspect ratio.

7. A method for inspecting deterioration of a paint film laminate used in painting an outdoor structure, the paint film laminate including a first paint that scatters electromagnetic waves in a specific band and a second paint that absorbs electromagnetic waves in the specific band, the method comprising: irradiating an area including the outdoor structure with electromagnetic waves in the specific band from above, and acquiring an image capturing the reflected electromagnetic waves; correlating the position on a map of the area including the outdoor structure with a position on the image; detecting a predetermined pattern from the image; and determining whether or not the pattern has been detected at a position on the image corresponding to the position of the outdoor structure on the map.

8. An inspection device used to inspect deterioration of a paint film laminate used in painting outdoor structures, the paint film laminate comprising a first paint that scatters electromagnetic waves in a specific band and a second paint that absorbs electromagnetic waves in the specific band, and which is placed on the surface of an outdoor structure, the inspection device comprising: an acquisition unit that irradiates electromagnetic waves in the specific band from above onto an area including the outdoor structure and acquires an image of the reflected electromagnetic waves; and a control unit that is capable of executing processing to associate the position on a map of the area including the outdoor structure with a position on the image, detect a predetermined pattern from the image, and determine whether the pattern has been detected at a position on the image that corresponds to the position of the outdoor structure on the map.

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