Covering sheet, steel structure, and method for repairing steel structure

Abstract

To provide a covering sheet that allows easy inspection of steel.SOLUTION: The present invention provides a covering sheet for use in covering steel. The covering sheet includes a first surface and a second surface. The first surface faces away from the steel. The total light transmittance is 70% or more. When measured by a reflection method with the first surface as the incident surface, image clarity is 5.0% or less. The maximum spectral transmittance in the wavelength range of 300 nm or more and 350 nm or less is 1.0% or less.SELECTED DRAWING: Figure 1A

Description

Technical Field

[0001] The present disclosure relates to a coated sheet, a steel structure, and a method for repairing a steel structure.

Background Art

[0002] Steel structures such as bridges contain steel materials. Steel materials deteriorate over time due to corrosion. Deteriorated steel materials become defects that can significantly reduce the strength of the steel structure. For this reason, a plurality of coating films for suppressing corrosion are laminated on the steel material. Examples of the coating film include a plurality of primer layers containing an epoxy resin, an intermediate coating layer containing a fluororesin, and a top coating layer containing a fluororesin.

[0003] Steel structures are inspected regularly. When a defect is found during inspection, the steel material is repaired. In conventional post-maintenance, major repairs were carried out after a major defect was found.

[0004] Recently, preventive maintenance has attracted attention. In preventive maintenance, repairs are carried out on the deteriorated parts of the steel material before reaching a major defect. The number of construction times for preventive maintenance is more than that for post-maintenance. However, one construction of preventive maintenance is much simpler compared to post-maintenance. Preventive maintenance does not require a high level of skill, unlike post-maintenance.

[0005] Patent Document 1 discloses a laminate including a fluororesin layer. Patent Document 1 proposes to facilitate preventive maintenance by using the laminate.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] A number of coating films are laminated on the steel material. To prevent missed coating, the coating films are usually colored. Therefore, it is not easy to detect slight deterioration of the steel material under the number of coating films.

[0008] In Patent Document 1, it is proposed to adjust the transmittance of the laminate and observe the steel material through the laminate. However, steel structures are usually arranged outdoors. Under sunlight, the laminate can reflect more light than the steel material. Due to the reflection by the laminate, it is impossible to easily detect the deterioration of the steel material through the laminate of Patent Document 1.

[0009] That is, even if preventive maintenance is to be adopted, it is impossible to easily inspect the steel material in the prior art. The present disclosure aims to facilitate the inspection of the steel material.

Means for Solving the Problems

[0010] A coating sheet according to an embodiment of the present disclosure is a coating sheet used for coating a steel material, comprising a first surface and a second surface, the first surface facing away from the steel material, the total light transmittance is 70% or more, the image sharpness with the first surface as the incident surface is 5.0% or less, the maximum spectral transmittance at a wavelength of 300 nm or more and 350 nm or less is 1.0% or less.

[0011] A steel structure according to an embodiment of the present disclosure is the steel material and a coating sheet according to an embodiment of the present disclosure.

[0012] A correction method for a steel structure according to an embodiment of the present disclosure is a step of performing substrate adjustment on a deteriorated part of the steel structure, and a step of joining a coating sheet according to an embodiment of the present disclosure to the substrate-adjusted steel material to coat the steel material with the coating sheet.

Advantages of the Invention

[0013] According to the present disclosure, the inspection of steel materials can be facilitated.

Brief Description of the Drawings

[0014]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 2C

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 4D

Figure 5

Embodiments for Carrying Out the Invention

[0015] One embodiment of the present disclosure relates to the following <1> to <12>.

[0016] <1> A coating sheet used for coating steel materials, comprising a first surface and a second surface, wherein the first surface faces away from the steel material, the total light transmittance is 70% or more, the image sharpness with the first surface as the incident surface is 5.0% or less, and the maximum spectral transmittance at a wavelength of 300 nm or more and 350 nm or less is 1.0% or less. The coating sheet.

[0017] <2> The transmission haze is 97% or less. The coating sheet according to <1>.

[0018] <3> comprising a base material and a weather-resistant layer in this order from the second surface toward the first surface, wherein the base material contains a polyolefin. The coating sheet according to <1> or <2>.

[0019] <4> comprising a base material and a weather-resistant layer in this order from the second surface toward the first surface, wherein the weather-resistant layer contains a cured product of an electron beam curable resin composition. The coating sheet according to any one of <1> to <3>.

[0020] <5> comprising a barrier layer and a weather-resistant layer in this order from the second surface toward the first surface, wherein the weather-resistant layer contains an ultraviolet absorber. The coating sheet according to any one of <1> to <4>.

[0021] <6> The water vapor permeability in an environment of a temperature of 40 °C and a humidity of 90% RH is 3.0 g / (m 2 ·day) or less. The coating sheet according to any one of <1> to <5>.

[0022] <7> wherein the weather-resistant layer contains an ultraviolet absorber. The steel material coating sheet according to any one of <1> to <6>.

[0023] <8> After a 408-hour weather resistance test, the total light transmittance is 70% or more, the image sharpness with the first surface as the incident surface is 7.0% or less, the maximum spectral transmittance at wavelengths from 300 nm to 350 nm is 1.0% or less. The coating sheet according to any one of <1> to <7>.

[0024] <9> The coating sheet according to any one of <1> to <8>, including a bonding layer and a base material in this order from the second surface toward the first surface.

[0025] <10> The coating sheet according to any one of <1> to <9>, including a release film, a bonding layer, and a base material in this order from the second surface toward the first surface.

[0026] <11> The steel material and A steel structure including the coating sheet according to any one of <1> to <10>.

[0027] <12> A step of performing substrate adjustment on the deteriorated part of the steel structure, A method for correcting a steel structure, including a step of coating the steel material substrate-adjusted by the coating sheet according to any one of <1> to <11>.

[0028] Hereinafter, details of an embodiment of the present disclosure will be described. In the drawings attached to this specification, for the convenience of easy understanding, the scale, the aspect ratio of the vertical and horizontal dimensions, etc. are appropriately changed and exaggerated from those of the actual object.

[0029] In this specification, terms such as "film", "sheet", and "plate" are not distinguished from each other based only on the difference in name. For example, a "repair sheet" cannot be distinguished from a member such as a repair film or a repair plate based only on the difference in name.

[0030] In this specification, the normal direction of a film-like (sheet-like, plate-like) member refers to a direction parallel to the normal or perpendicular line to the film surface (sheet surface, plate surface) of the target film-like (sheet-like, plate-like) member. The "film surface (sheet surface, plate surface)" refers to the surface that coincides with the target film-like (sheet-like, plate-like) member when the target film-like (sheet-like, plate-like) member is viewed as a whole and globally. FIGS. 1A to 2C all show cross-sections along the normal direction of the coating sheet.

[0031] In this specification, a plurality of upper limit candidates for a numerical range and a plurality of lower limit candidates may be described in separate sentences. In this description, the numerical range may be constituted by combining any one upper limit candidate and any one lower limit candidate. As an example, consider the description "Parameter B may be A1 or more, A2 or more, or A3 or more. Parameter B may be A4 or less, A5 or less, or A6 or less." In this example, the numerical range of Parameter B may be A1 or more and A4 or less, A1 or more and A5 or less, A1 or more and A6 or less, A2 or more and A4 or less, A2 or more and A5 or less, A2 or more and A6 or less, A3 or more and A4 or less, A3 or more and A5 or less, or A3 or more and A6 or less.

[0032] <<<Steel structure>>> As shown in FIGS. 1A to 1C, the steel structure 10 includes a steel material 20 and a coating sheet 30. The coating sheet 30 is used for coating the steel material 20. The coating sheet 30 includes a first surface 31 and a second surface 32. The second surface 32 faces the steel material 20. The first surface 31 faces the side opposite to the steel material 20. The first surface 31 may constitute the surface 11 of the steel structure 10.

[0033] The steel structure 10 shown in FIG. 1A includes the steel material 20 and the coating sheet 30 in this order in the stacking direction. The coating sheet 30 is directly joined to the steel material 20. The second surface 32 of the coating sheet 30 is in contact with the steel material 20.

[0034] In the example shown in FIG. 1B, the steel structure 10 includes a steel material 20, a bonding layer 15, and a coating sheet 30 in this order in the stacking direction. The bonding layer 15 is located between the steel material 20 and the coating sheet 30 in the stacking direction. The bonding layer 15 is in contact with the steel material 20 and the coating sheet 30. The bonding layer 15 is bonded to the steel material 20 and the coating sheet 30. The steel structure 10 shown in FIG. 1B is different from the example shown in FIG. 1A in that it includes the bonding layer 15. The steel structure 10 shown in FIG. 1B may be configured in the same manner as the steel structure 10 shown in FIG. 1A in other respects.

[0035] In order to distinguish it from the bonding layers 43 and 45 described later included in the coating sheet 30, the bonding layer 15 may also be referred to as the third bonding layer hereinafter.

[0036] In the example shown in FIG. 1C, the steel structure 10 includes a steel material 20, a rust preventive layer 18, a bonding layer 15, and a coating sheet 30 in this order in the stacking direction. The rust preventive layer 18 is located between the steel material 20 and the bonding layer 15 in the stacking direction. The rust preventive layer 18 is in contact with the steel material 20 and the bonding layer 15. The steel structure 10 shown in FIG. 1C is different from the example shown in FIG. 1B in that it includes the rust preventive layer 18. The steel structure 10 shown in FIG. 1C may be configured in the same manner as the steel structure 10 shown in FIG. 1B in other respects.

[0037] In the example shown in FIG. 1C, the bonding layer 15 may be omitted. Alternatively, the rust preventive layer 18 shown in FIG. 1C may be included in the steel structure 10 shown in FIG. 1A. Not limited to the examples shown in FIGS. 1A to 1C, the steel structure 10 may include further layers. As an example, as shown by the two-dot chain line in FIG. 1C, the steel structure 10 may include a topcoat layer 19 that constitutes the outermost layer. In this example, the coating sheet 30 may be located between the topcoat layer 19 and the steel material 20 in the stacking direction. The topcoat layer 19 may have one or more of the functions expected of the outermost layer, such as barrier properties, weather resistance, scratch resistance, strength, etc.

[0038] The steel structure 10 is a structure including steel materials 20. The steel materials 20 may constitute the base of the steel structure 10. Examples of the steel structure 10 include bridges, bridge piers, towers, steel pipes, chimneys, tanks, plants, pipelines, rolled plates, and roofs. The steel structure may be, for example, a building structure or a civil engineering structure.

[0039] Examples of the steel materials 20 include alloy steels such as nickel chromium steel, nickel chromium molybdenum steel, chromium steel, chromium molybdenum steel, and manganese steel, as well as carbon steel. The steel materials 20 can be corroded by corrosion factors such as water and oxygen. The steel materials 20 may include, on the surface, a rusted portion where rust has occurred due to corrosion. Examples of rust include red rust such as iron oxide (Fe2O3). The portion where abnormalities such as rusting of the steel materials 20 occur constitutes the deteriorated portion 12 of the steel structure 10.

[0040] The steel structure 10 may include a coating film that coats the steel materials 20. The coating film may be provided for the purpose of suppressing deterioration of the steel materials 20. As an example of the coating film, the rust prevention layer 18 shown in FIG. 1C is exemplified. Abnormalities such as cracks and bulges may occur in the coating film due to aging deterioration or due to construction or repair performed on the steel structure. The portion where defects such as cracks and bulges in the coating film occur also constitutes the deteriorated portion 12 of the steel structure.

[0041] The covering sheet 30 is used for covering the steel materials 20. The covering sheet 30 may protect the steel materials 20 by covering the steel materials 20. The covering sheet 30 may suppress deterioration of the steel materials 20. The covering sheet 30 may be laminated on the steel materials 20 at the time of new construction of the steel structure 10. The covering sheet 30 may be used for repairing the steel structure 10 having the deteriorated portion 12. The covering sheet 30 used for repair may be laminated on the portion of the steel structure 10 where the deteriorated portion 12 has been removed.

[0042] <<<Covering Sheet>>> The coating sheet 30 according to the present embodiment is devised to facilitate the inspection of the steel material 20. According to the coating sheet 30 of the present embodiment, abnormalities occurring in the steel material 20 can be easily and stably detected through the coating sheet 30 that covers the steel material 20. Thereby, the inspection of the steel material 20 can be facilitated.

[0043] Specifically, the coating sheet 30 according to the present embodiment has the following features (A) to (C). Feature (A): The total light transmittance is 70% or more. Feature (B): The image sharpness with the first surface 31 as the incident surface is 5.0% or less. Feature (C): The maximum spectral transmittance at a wavelength of 300 nm or more and 350 nm or less is 1.0% or less.

[0044] According to feature (A), the state of the steel material 20 can be easily observed through the coating sheet 30.

[0045] Also, according to feature (B), it is possible to suppress the reflection of an external image on the coating sheet 30. The steel structure 10 is usually installed outdoors. The inspection of the steel structure 10 is carried out in sunlight. According to the coating sheet 30 having feature (B), it is possible to effectively suppress the reflection of the sun and an image reflecting sunlight on the coating sheet 30. Therefore, feature (B) can suppress the situation where it becomes difficult to observe abnormalities occurring in the steel material 20 through the coating sheet 30 due to the reflection of an external image.

[0046] According to feature (C), deterioration of the coating sheet 30 can be suppressed. The coating sheet 30 is assumed to be installed outdoors. The coating sheet 30 having feature (C) is suppressed from deteriorating due to strong ultraviolet rays contained in sunlight. Therefore, feature (C) can suppress the situation where it becomes difficult to observe abnormalities occurring in the steel material 20 of the steel structure 10 through the coating sheet 30 due to the deterioration of the coating sheet 30.

[0047] As described above, according to the coating sheet 30 having the features (A) to (C), it is possible to easily detect abnormalities in the steel material 20. That is, according to the combination of the features (A) to (C), the inspection of the steel material 20 can be facilitated.

[0048] Steel structures are regularly inspected. When a defect is found during the inspection, the steel material is repaired. In the previous post-maintenance, major repairs were carried out after a major defect occurred up to the outermost layer of the steel structure or after a long period had elapsed since installation or the previous repair. Such a maintenance method is called post-maintenance. In a single repair in post-maintenance, the construction period becomes long. The construction difficulty of repair in post-maintenance is high. High proficiency is required for the repair in post-maintenance. Problems such as construction costs and the arrangement of construction workers in post-maintenance have become serious.

[0049] Under such circumstances, preventive maintenance has attracted attention. In preventive maintenance, repairs are carried out on the deteriorated parts of the steel structure before reaching a major defect. The number of construction times for preventive maintenance is more than that for post-maintenance. However, a single construction of preventive maintenance is much simpler compared to post-maintenance. Different from post-maintenance, preventive maintenance does not require a high level of proficiency.

[0050] As described above, according to the combination of the features (A) to (C), the inspection of the steel structure 10 can be facilitated. In particular, even minor abnormalities before reaching a major defect can be stably detected through the coating sheet 30. Therefore, according to the combination of the features (A) to (C), the effectiveness of preventive maintenance can be improved. The effect that the effectiveness of preventive maintenance regarding the steel structure 10 can be improved by such a combination of the features (A) to (C) can be said to be a heterogeneous or remarkable effect exceeding the range predicted from the technical level.

[0051] <<Feature (A)>> In the feature (A), the total light transmittance of the coating sheet 30 is defined. The total light transmittance is an index indicating the ease of detecting abnormalities in the steel material 20 when observing through the coating sheet 30.

[0052] By setting the lower limit of the total light transmittance of the coating sheet 30, it is possible to facilitate the inspection of the steel material 20 through the coating sheet 30. The total light transmittance of the coating sheet 30 is 70% or more, may be 80% or more, or may be 85% or more. The total light transmittance of the coating sheet 30 does not particularly have an upper limit. The total light transmittance of the coating sheet 30 may be 100% or less, or may be less than 100%.

[0053] A D65 light source is used for measuring the total light transmittance. Before measuring the total light transmittance of the coating sheet 30, the D65 light source is turned on for 15 minutes to stabilize the output of the D65 light source. The incident angle to the sample when measuring the total light transmittance is set to 0°. The incident surface when measuring the total light transmittance is the second surface 32 of the coating sheet 30. The test environment when measuring the total light transmittance is a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. The sample is placed in the test environment for 16 hours before the start of the test. Other measurement conditions when measuring the total light transmittance follow JIS K7361-1:1997.

[0054] The total light transmittance is the arithmetic mean value of five measured values. The five measured values are the measured values obtained at five measurement positions on the coating sheet 30 to be evaluated. The five measurement positions are located at least 10 mm apart from each other.

[0055] <<Feature (B)>> In Feature (B), the image sharpness (%) of the coating sheet 30 is defined. The image sharpness is measured by reflected light. The image sharpness by the reflection method is an index indicating the degree of reflection of the external image.

[0056] As confirmed by the inventors of the present case, physical property values such as specular glossiness, specular reflectance, and total light reflectance did not sufficiently reflect the degree of reflection of the steel material 20 on the coating sheet 30. On the other hand, the image sharpness by the reflection method at the first surface 31 showed a strong correlation with the degree of reflection of the steel material 20 on the coating sheet 30.

[0057] By setting an upper limit on the image sharpness (%) with the first surface 31 as the incident surface, it is possible to suppress the reflection of external images that obstruct clear observation of the steel material 20 through the coating sheet 30. The image sharpness (%) with the first surface 31 as the incident surface is 5.0% or less, may be 4.5% or less, and may be 4.3% or less.

[0058] The image sharpness (%) with the first surface 31 as the incident surface may be 0.50% or more, may be 1.0% or more, and may be 1.5% or more. By setting a lower limit on the image sharpness (%) with the first surface 31 as the incident surface, it is possible to suppress the situation where abnormalities in the steel material 20 become less distinct and difficult to observe.

[0059] The image sharpness by the reflection method can be adjusted according to the manufacturing conditions, composition, materials, etc. of the layers contained in the coating sheet 30, particularly the layer constituting the first surface 31. For example, by strengthening the drying conditions of the coating layer, the image sharpness by the reflection method can be reduced. By increasing the size of the additive contained in the layer, the image sharpness by the reflection method can be reduced. By increasing the content or proportion of the additive contained in the layer, the image sharpness by the reflection method can be reduced.

[0060] Image sharpness is also called DOI or imaging property. Image sharpness is the value measured by the appearance analyzer "Rhopoint IQ S / Flex20" manufactured by Konica Minolta. The incident surface during measurement is the first surface 31 of the coating sheet 30. The incident angle during measurement is 20°. The incident angle is the angle (°) between the incident direction and the normal direction of the incident surface. Therefore, the incident angle can take a value of 0° or more and 90° or less.

[0061] When measuring the image sharpness, the sample to be measured is placed on black cardboard. The image sharpness is measured in a state where the back surface (second surface 32) facing the incident surface (first surface 31) of the sample to be measured is in contact with the black cardboard.

[0062] The measurement environment when measuring the image sharpness is a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. The measurement sample is placed in the measurement environment for 16 hours before the start of measurement.

[0063] The image sharpness shall be the arithmetic mean value of five measurement values. The five measurement values shall be the measurement values measured at five measurement positions of the antiglare sheet to be evaluated. The five measurement positions are located at least 10 mm apart from each other.

[0064] <<Characteristic (C)>> In characteristic (C), an upper limit is set for the spectral transmittance in the ultraviolet wavelength range of 300 nm or more and 350 nm or less. The spectral transmittance in the ultraviolet wavelength range is an indicator of weather resistance.

[0065] By setting an upper limit for the maximum spectral transmittance at a wavelength of 300 nm or more and 350 nm or less for the coating sheet 30, excellent weather resistance can be imparted to the coating sheet 30. The maximum spectral transmittance at a wavelength of 300 nm or more and 350 nm or less may be 1.0% or less, or may be 0.50% or less. According to such a coating sheet 30, ultraviolet degradation in outdoor installation applications can be effectively suppressed. The coating sheet 30 can protect the steel material 20 and the coating film over a long period of time.

[0066] The maximum transmittance at a wavelength of 300 nm or more and 350 nm or less for the coating sheet 30 has no particular lower limit. The maximum transmittance at a wavelength of 300 nm or more and 350 nm or less for the coating sheet 30 may be 0% or more, or may be greater than 0%.

[0067] The transmittance at each wavelength, that is, the spectral transmittance, shall be the arithmetic mean value of five measurement values measured in accordance with JIS Z8722:2009. The five measurement values shall be the measurement values measured at five measurement positions of the sample of the coating sheet 30 to be evaluated. The five measurement positions are located at least 10 mm apart from each other.

[0068] The measurement wavelengths of the spectral transmittance shall be wavelengths at 1 nm intervals in the range of 300 nm or more and 350 nm or less. That is, the spectral transmittance is measured for light with integer wavelengths (nm) of 300 nm or more and 350 nm or less. In the measurement of the spectral transmittance, the geometric condition f specified in JIS Z8722:2009 is adopted.

[0069] The incident angle to the sample when measuring the spectral transmittance shall be 0°. The incident plane when measuring the spectral transmittance shall be the first surface 31 of the coating sheet 30.

[0070] The test environment when measuring the spectral transmittance shall be a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. The sample shall be placed in the test environment for 16 hours before the start of the test. Before measuring the spectral transmittance, the light source of the measuring device shall be turned on for 15 minutes to stabilize the output of the light source.

[0071] <<Characteristic (D)>> In addition to characteristics (A) to (C), the coating sheet 30 according to this embodiment may have the following characteristic (D). Characteristic (D): The transmission haze of the coating sheet 30 is 97% or less.

[0072] In characteristic (D), the transmission haze of the coating sheet 30 is defined. The transmission haze is an index indicating the ease of detecting abnormalities in the steel material 20 when observing through the coating sheet 30.

[0073] By setting the upper limit of the transmission haze of the coating sheet 30, the inspection of the steel material 20 through the coating sheet 30 can be facilitated. The transmission haze of the coating sheet 30 may be 97% or less, may be 90% or more, may be 86% or more, may be 85% or more. It may be 80% or less, may be 75% or less. The transmission haze of the coating sheet 30 does not particularly have a lower limit. The transmission haze of the coating sheet 30 may be 0% or more, may be greater than 0%.

[0074] A D65 light source is used for measuring the transmission haze. Before measuring the transmission haze of the coating sheet 30, the D65 light source is turned on for 15 minutes to stabilize the output of the D65 light source. The incident angle to the sample when measuring the transmission haze shall be 0°. The incident plane when measuring the transmission haze shall be the second surface 32 of the coating sheet 30. The test environment when measuring the transmission haze shall be a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. The sample shall be placed in the test environment for 16 hours before the start of the test. Other measurement conditions when measuring the transmission haze shall follow JIS K7136:2000.

[0075] The haze is taken as the arithmetic mean value of five measurement values. The five measurement values are the measurement values measured at five measurement positions of the coating sheet 30 to be evaluated. The five measurement positions are located at least 10 mm apart from each other.

[0076] <<Characteristic (E)>> In addition to the characteristics (A) to (C), the coating sheet 30 according to the present embodiment may have the following characteristic (E). The characteristic (E) relates to the physical properties of the coating sheet 30 after a long period of time has passed. Characteristic (E): After a 408-hour weather resistance test, (E1) The total light transmittance is 70% or more (E2) The image sharpness with the first surface as the incident surface is 7.0% or less (E3) The maximum transmittance at wavelengths from 300 nm to 350 nm is 1.0% or less

[0077] The surface of the coating sheet 30 installed outdoors for a long time may be roughened. The coating sheet 30 installed outdoors for a long time may be discolored. As a result of these, the total light transmittance of the coating sheet 30 installed outdoors for a long time may decrease. On the other hand, by imparting high strength and excellent weather resistance to the coating sheet 30, it is possible to suppress the decrease over time in the total light transmittance of the coating sheet 30 after a long period of time has passed. Thereby, the characteristic (E1) can be realized. That is, as defined by the characteristic (E1), the coating sheet 30 after a long period of time maintains a total light transmittance of a certain level or more. According to the characteristic (E1), the state of the steel material 20 can be easily observed through the coating sheet 30 after a long period of time has passed.

[0078] The surface of the coating sheet 30 installed outdoors for a long time can be flattened. By flattening, the image sharpness by the reflection method can be increased. On the other hand, by imparting excellent weather resistance to the coating sheet 30, the increase in image sharpness over time by the reflection method can be suppressed. Thereby, the feature (E2) can be realized. That is, as defined by the feature (E2), for the coating sheet 30 after a long period of time, the image sharpness with the first surface as the incident surface is 7.0% or less. According to the feature (E2), it is possible to suppress the reflection of an external image on the coating sheet 30 after a long period of time.

[0079] Regarding the coating sheet 30 installed outdoors for a long time, the weather resistance may decrease due to the bleed-out of additives such as ultraviolet absorbers. On the other hand, the coating sheet 30 with high strength can suppress the bleed-out of additives. Thereby, the feature (E3) can be realized. That is, as defined by the feature (E3), the coating sheet 30 after a long period of time can maintain high ultraviolet light shielding properties. The weather resistance of the coating sheet 30 after a long period of time can be maintained. It is possible to suppress the deterioration of the coating sheet 30 due to outdoor installation over a long period of time.

[0080] As described above, according to the coating sheet 30 having the feature (E), it is possible to easily detect abnormalities in the steel material 20 over a long period of time. That is, according to the feature (E), it is possible to facilitate the inspection of the steel material 20 over a long period of time. Therefore, over a long period of time, even minor abnormalities before reaching serious defects can be stably detected through the coating sheet 30. Thereby, the effectiveness of preventive maintenance regarding the steel structure 10 can be highly maintained.

[0081] The 408-hour weather resistance test defined by the feature (E) is carried out as follows. The weather resistance test is carried out using a weather resistance test apparatus. For the coating sheet 30 to be evaluated, a 20-hour irradiation process and a 4-hour dew condensation process are taken as one cycle, and the cycle is repeatedly carried out until 408 hours are reached. A 30-second shower process is carried out before starting the dew condensation process after the irradiation process and before starting the irradiation process after the dew condensation process. In the shower process, the sample held in the weather resistance test apparatus is exposed to a water shower.

[0082] As a weather resistance test device, the "Eye Super UV Tester SUV-W261", a super accelerated weather resistance test device manufactured by Iwasaki Electric Co., Ltd., is used. The UV lamp, lamp jacket, and illuminometer included in the weather resistance test device shall be as follows. · UV lamp: Product name: M04-L21WB / SUV, manufactured by Iwasaki Electric Co., Ltd. · Lamp jacket: Product name: WJ50-SUV, manufactured by Iwasaki Electric Co., Ltd. · Illuminometer: Product name: UVD-365PD, manufactured by Iwasaki Electric Co., Ltd.

[0083] The conditions of the irradiation process shall be as follows. <Irradiation conditions> · Black panel temperature: 63°C · Illuminance: 100 mW / cm 2 · Humidity inside the tank: 50% RH · Time: 20 hours

[0084] The conditions of the dew condensation process shall be as follows. <Irradiation conditions> · Black panel temperature: 30°C · Illuminance: 0 mW / cm 2 · Humidity inside the tank: 98% RH · Time: 4 hours

[0085] <<Layer structure of the coating sheet>> As shown in FIG. 2A, the coating sheet 30 may include an adhesive layer 43, a base material 41, and a weather resistance layer 42 in this order from the second surface 32 to the first surface 31 in the lamination direction. The coating sheet 30 shown in FIG. 2A may be included in the steel structure 10 shown in FIG. 1A. In the example shown in FIG. 2A, the weather resistance layer 42 constitutes the first surface 31. The adhesive layer 43 constitutes the second surface 32. The adhesive layer 43 is in contact with the steel material 20. The adhesive layer 43 may be joined to the steel material 20.

[0086] As shown in FIG. 2B, the bonding layer 43 may be omitted. As shown in FIG. 2B, the coating sheet 30 may include a base material 41 and a weather-resistant layer 42 in this order from the second surface 32 to the first surface 31 in the stacking direction. The coating sheet 30 shown in FIG. 2B may be included in the steel structure 10 shown in FIG. 1A. The coating sheet 30 shown in FIG. 2B may be included in the steel structures 10 shown in FIGS. 1B and 1C. In the examples shown in FIGS. 1B and 1C, the coating sheet 30 is bonded to the steel material 20 by the bonding layer 15. The coating sheet 30 may be welded to the steel material 20 without using a bonding layer.

[0087] As shown in FIG. 2C, the coating sheet 30 may include a barrier layer 44. The coating sheet 30 may include a barrier layer 44 and a base material 41 in this order from the second surface 32 to the first surface 31 in the stacking direction. The coating sheet 30 shown in FIG. 2C includes a bonding layer 43, a barrier layer 44, a second bonding layer 45, a base material 41, and a weather-resistant layer 42 in this order from the second surface 32 to the first surface 31 in the stacking direction. The coating sheet 30 shown in FIG. 1C may be included in the steel structure 10 shown in FIG. 1A. In the example shown in FIG. 2C, the bonding layer 43 and the second bonding layer 45 may be omitted.

[0088] Each layer that may be included in the coating sheet 30 will be described in further detail.

[0089] <Base Material> The base material 41 may be a resin film. Examples of the resin material constituting the base material 41 include polyolefins such as polyethylene and polypropylene, polyvinyl chloride, vinylidene chloride-vinyl chloride copolymer, polyesters such as polyethylene terephthalate, polycarbonate, polyarylate, styrene resin, acrylic resin, acrylic urethane resin, urethane resin, fluororesin, acetyl cellulose, polyamide, and polyimide. The base material 41 may be a single layer or multiple layers. The base material 41 may be a laminated film of resin films.

[0090] The base material 41 may have a bubble structure (cell structure). The bubble structure (cell structure) may be a closed-cell structure, an open-cell structure, or a semi-continuous and semi-independent bubble structure in which a closed-cell structure and an open-cell structure coexist. As the base material 41 having a bubble structure, a foam layer is exemplified. More specifically, as the base material 41, acrylic resin foam (acrylic foam), urethane resin foam (urethane foam), polyolefin foam, and rubber foam containing acrylic rubber and other elastomers are exemplified.

[0091] The base material 41 may contain additives. Examples of the additives include pigments, dyes, colorants, antistatic agents, flame retardants, fungicides, plasticizers, leveling agents, flow regulators, defoamers, and dispersants. The base material 41 may contain weathering agents such as ultraviolet absorbers, antioxidants, and light stabilizers. The base material 41 containing a weathering agent has excellent weather resistance. Since the base material 41 has weather resistance, the topcoat layer described later may be made thinner or the topcoat layer may be omitted.

[0092] The thickness of the base material 41 may be determined in consideration of the finish after repairing the steel structure, that is, the finish after attaching the coating sheet 30 to the steel material 20, the handleability and ease of attachment of the coating sheet 30, etc. The thickness of the base material 41 may be 10 μm or more, 20 μm or more, 30 μm or more, 50 μm or more, or 100 μm or more. The thickness of the base material 41 may be 5000 μm or less, 4000 μm or less, 3000 μm or less, 2000 μm or less, or 1000 μm or less.

[0093] The base material 41 may include a fiber-reinforced resin layer. According to the fiber-reinforced resin layer, the impact resistance of the base material 41 and the coating sheet 30 can be improved. The fiber-reinforced resin layer may include a resin material and reinforcing fibers. As the resin material, the resin materials that can be used for the above-described base material 41 are exemplified. The reinforcing fibers may be inorganic fibers or organic fibers. Examples of the inorganic fibers include glass fibers, carbon fibers, silicon-titanium-carbon fibers, boron fibers, and metal fibers. Examples of the organic fibers include aramid fibers, vinylon fibers, polyester fibers, and polyamide fibers. The reinforcing fibers may be in a mesh (network) form. The fiber-reinforced resin layer may include a glass mesh as the reinforcing fibers.

[0094] The thickness of the fiber-reinforced resin layer may be 50 μm or more, 75 μm or more, 100 μm or more, 125 μm or more, or 150 μm or more. The thickness of the fiber-reinforced resin layer may be 550 μm or less, 525 μm or less, 500 μm or less, 475 μm or less, or 450 μm or less. By setting the thickness of the fiber-reinforced resin layer in this way, impact resistance can be imparted to the coating sheet 30.

[0095] The base material 41 may include a laminate including a fiber-reinforced resin layer and a resin layer. The base material 41 may include a laminate including a first resin layer, a fiber-reinforced resin layer, and a second resin layer. As the resin materials constituting the resin layer, the first resin layer, and the second resin layer, the resin materials that can be used for the above-described base material 41 are exemplified. The laminate included in the base material 41 may include a fiber-reinforced resin layer including polyethylene and a glass mesh and a polyethylene layer. The laminate included in the base material 41 may include a first polyethylene layer, a fiber-reinforced resin layer including polyethylene and a glass mesh, and a second polyethylene layer.

[0096] The thickness of the resin layer, the thickness of the first resin layer, and the thickness of the second resin layer may each be 10 μm or more, 20 μm or more, 30 μm or more, 50 μm or more, or 100 μm or more. The thickness of the resin layer, the thickness of the first resin layer, and the thickness of the second resin layer may each be 1000 μm or less, 800 μm or less, 600 μm or less, 500 μm or less, or 400 μm or less.

[0097] <Weather-resistant layer> The weather-resistant layer 42 is a layer having weather resistance. The weather-resistant layer 42 may contain a binder resin and a weathering agent. The weather-resistant layer 42 may contain, as the weathering agent, one or more of an ultraviolet absorber, an antioxidant, and a light stabilizer.

[0098] The weather-resistant layer 42 may contain a resin cured product as the binder resin. The resin cured product is a cured product of a curable resin composition. The curable resin composition may be a thermosetting resin composition. The curable resin composition may be an ionizing radiation curable resin composition. The weather-resistant layer 42 may contain a cured product of a curable resin composition and a cured product of an ionizing radiation curable resin composition.

[0099] The thermosetting resin composition contains a thermosetting resin. The thermosetting resin composition cures by heating. Examples of the thermosetting resin include an unsaturated group-containing (meth)acrylic resin, an unsaturated polyester, a urethane resin, an epoxy resin, a phenol resin, an aminoalkyd resin, a urea resin, a melamine resin, a melamine-urea co-condensation resin, a guanamine resin, a diallyl phthalate resin, and a silicone resin.

[0100] The thermosetting resin composition may contain a curing agent together with the thermosetting resin. In the case of an unsaturated group-containing (meth)acrylic resin and an unsaturated polyester, peroxides such as methyl ethyl ketone peroxide and radical initiators such as azoisobutyronitrile may be used. In the case of a urethane resin, an isocyanate-based curing agent may be used. In the case of an epoxy resin, an organic amine-based curing agent may be used.

[0101] The thermosetting resin may be a two-component curable urethane resin having a polyol as the main agent and an isocyanate compound as the curing agent. Examples of the polyol include (meth)acrylic polyol, polyether polyol, polyester polyol, polyethylene glycol, and polypropylene glycol. The isocyanate compound is a polyvalent isocyanate having two or more isocyanate groups. Examples of the isocyanate compound include aromatic isocyanates such as 4,4-diphenylmethane diisocyanate; aliphatic (or alicyclic) isocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated diphenylmethane diisocyanate.

[0102] In one specific example of the weather-resistant layer 42, the cured resin contained in the weather-resistant layer 42 may be a crosslinked cured product of (meth)acrylic polyol with an isocyanate-based curing agent.

[0103] The ionizing radiation curable resin composition contains a compound having an ionizing radiation curable functional group. Hereinafter, the compound having an ionizing radiation curable functional group is also referred to as an "ionizing radiation curable compound". The ionizing radiation curable functional group is a group that crosslinks upon irradiation with ionizing radiation.

[0104] The ionizing radiation may be an electromagnetic wave or a charged particle beam. The ionizing radiation has energy quanta capable of polymerizing or crosslinking molecules. Examples of the ionizing radiation include ultraviolet rays (UV), electron beams (EB), X-rays, γ-rays, α-rays, ion beams, etc. In the example where the weather-resistant layer 42 contains an ultraviolet absorber as a weathering agent, the ionizing radiation may be an electron beam.

[0105] Examples of the ionizing radiation-curable functional group include ethylenically unsaturated bond groups such as (meth)acryloyl group, vinyl group, and allyl group, and epoxy group, oxetanyl group, etc. The ionizing radiation-curable compound may contain an ethylenically unsaturated bond group. The ionizing radiation-curable compound may contain two or more ethylenically unsaturated bond groups. The ionizing radiation-curable compound may be a polyfunctional (meth)acrylate-based compound containing two or more ethylenically unsaturated bond groups. The polyfunctional (meth)acrylate-based compound may contain either a monomer or an oligomer.

[0106] Examples of the polymerizable monomer include (meth)acrylate monomers having a (meth)acryloyl group in the molecule and polyfunctional (meth)acrylate monomers having two or more (meth)acryloyl groups in the molecule. The number of (meth)acryloyl groups in the polyfunctional (meth)acrylate monomer may be 2 or more and 8 or less, or may be 2 or more and 6 or less.

[0107] Examples of the polymerizable monomer include difunctional (meth)acrylates such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, bisphenol A tetraethoxydi(meth)acrylate, and bisphenol A tetrapropoxydi(meth)acrylate; polyfunctional (meth)acrylates having three or more functional groups such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tri(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate; and ethylene oxide-modified products, propylene oxide-modified products, caprolactone-modified products, isocyanuric acid-modified products, or propionic acid-modified products of these (meth)acrylates.

[0108] Examples of the polymerizable oligomer include (meth)acrylate oligomers having two or more (meth)acryloyl groups in the molecule. Examples of the (meth)acrylate oligomer include urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, polycarbonate (meth)acrylate, polycaprolactone urethane (meth)acrylate, polycaprolactone diol urethane (meth)acrylate, and acrylic (meth)acrylate. The number of (meth)acryloyl groups in the polymerizable oligomer may be 2 or more and 8 or less, or may be 2 or more and 6 or less.

[0109] Examples of the polymerizable oligomer also include highly hydrophobic polybutadiene (meth)acrylate-based oligomers having a (meth)acryloyl group in the side chain of a polybutadiene oligomer, and silicone (meth)acrylate-based oligomers having a polysiloxane bond in the main chain.

[0110] The weight average molecular weight of the polymerizable oligomer may be 500 or more, may be 1,000 or more, or may be 2,000 or more. The weight average molecular weight of the polymerizable oligomer may be 10,000 or less, may be 8,000 or less, or may be 6,000 or less. The weight average molecular weight is measured by gel permeation chromatography (GPC) analysis and is the average molecular weight converted with standard polystyrene.

[0111] As the radiation curable compound, a monofunctional (meth)acrylate may be used together with the polyfunctional (meth)acrylate. According to this example, the viscosity of the curable composition during coating can be reduced. Examples of the monofunctional (meth)acrylate include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and isobornyl (meth)acrylate.

[0112] When the radiation-curable compound is an ultraviolet-curable compound, at least one selected from a photopolymerization initiator and a photopolymerization accelerator may be used together with the ultraviolet-curable compound.

[0113] From the viewpoint of excellent heat resistance, abrasion resistance, stain resistance, etc., the weather-resistant layer 42 may contain a cured product of a curable compound or may contain a cured product of a radiation-curable composition. A coating solution containing an electron beam-curable compound can be solvent-free and does not require a photopolymerization initiator. The electron beam-curable compound can obtain stable curing characteristics. In addition, the electron beam-curable compound can stably hold additives such as weathering agents, for example, ultraviolet absorbers, by crosslinking. Therefore, bleeding out of additives such as ultraviolet absorbers can be stably suppressed. Thereby, it is possible to suppress the deterioration over time of the excellent weather resistance of the weather-resistant layer 42. From the above, preferably, the weather-resistant layer 42 contains a cured product of an electron beam-curable compound. The radiation-curable compound may be a polymerizable oligomer, a (meth)acrylate oligomer having two or more (meth)acryloyl groups in the molecule, or a urethane (meth)acrylate.

[0114] With respect to all the resin components contained in the weather-resistant layer 42, the content ratio of the cured resin may be 50% by mass or more, 70% by mass or more, 80% by mass or more, or 90% by mass or more.

[0115] The weather-resistant layer 42 can be produced by forming a coating film of a coating solution containing a curable resin composition and curing the coating film. In an example where the weather-resistant layer 42 contains a cured product of an electron beam-curable resin composition, the coating film is irradiated with an electron beam. A part of this electron beam penetrates the coating film and is also irradiated onto the base material 41. In this example, the base material 41 may contain a polyolefin. The polyolefin is crosslinked to some extent by the electron beam. The heat resistance of the base material 41 is improved by the crosslinking of the polyolefin.

[0116] The base material 41 containing polyolefin can improve the adhesion with the weather-resistant layer 42 containing the cured product of the electron beam curable resin composition as compared with the base material containing a fluororesin. Further, by using polyolefin for the base material 41 instead of the fluororesin, the generation of PFAS as an impurity can be suppressed. PFAS, as an artificial organic fluorine compound, is a concern for bioaccumulation. By suppressing the generation of PFAS, it can contribute to reducing the environmental load.

[0117] From the above points, in combination with the weather-resistant layer 42 containing the cured product of the electron beam curable resin composition, the base material 41 may contain polyolefin. Examples of the polyolefin used for the base material 41 include polyethylene, polypropylene, polybutene, and polymethylpentene.

[0118] Examples of polypropylene include homopolymers of propylene and copolymers such as ethylene-propylene copolymers, propylene-butene copolymers, and ethylene-propylene-butene copolymers. As the polypropylene contained in the base material 41, a homopolymer of propylene, an ethylene-propylene copolymer, or a propylene-butene copolymer is preferable.

[0119] From the viewpoint of processability, the content ratio of polyolefin in the base material 41 may be 50% by mass or more, 60% by mass or more, 70% by mass or more, or 80% by mass or more with respect to all the resin components of the base material 41.

[0120] <Barrier layer> The barrier layer 44 may be a vapor deposition film formed on the resin film. The coating sheet 30 may include a barrier film including the barrier layer 44 and the resin film. The barrier layer 44 may be a vapor deposition film formed on the base material 41. When the barrier layer 44 constitutes a barrier film together with the base material 41, the second bonding layer 45 shown in FIG. 2C can be omitted.

[0121] The coating sheet 30 including the barrier layer 44 can have excellent gas barrier properties. The coating sheet 30 including the barrier layer 44 can have excellent oxygen barrier properties and excellent water vapor barrier properties. By the coating sheet 30 including the barrier layer 44, rusting of the steel material 20 and deterioration of the coating film on the steel material 20 can be suppressed.

[0122] As the resin film used for the barrier film, the resin film constituting the above-described base material 41 is exemplified. The thickness of the resin film may be 5 μm or more, may be 10 μm or more, may be 100 μm or less, or may be 50 μm or less.

[0123] The barrier layer 44 may be a vapor deposition film containing one or more metals, may be a vapor deposition film containing one or more inorganic oxides, or may be a vapor deposition film containing one or more metals and one or more inorganic oxides. Examples of the metal contained in the vapor deposition film include aluminum, chromium, tin, nickel, copper, silver, gold, and platinum. Examples of the inorganic oxide include aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, barium oxide, and silicon carbide oxide (carbon-containing silicon oxide). As a specific example, the barrier layer 44 may include one or more of an aluminum vapor deposition film, an aluminum oxide (alumina) vapor deposition film, and a silicon oxide (silica) vapor deposition film.

[0124] The thickness of the vapor deposition film may be 1 nm or more, may be 5 nm or more, or may be 10 nm or more. The thickness of the vapor deposition film may be 150 nm or less, may be 100 nm or less, or may be 80 nm or less.

[0125] The vapor deposition film constituting the barrier layer 44 may be formed by a physical vapor deposition method (Physical Vapor Deposition method, PVD method) such as a vacuum vapor deposition method, a sputtering method, and an ion plating method. The vapor deposition film constituting the barrier layer 44 may be formed by a chemical vapor deposition method (Chemical Vapor Deposition method, CVD method) such as a plasma chemical vapor deposition method, a thermal chemical vapor deposition method, and a photo chemical vapor deposition method.

[0126] Examples of the vapor deposition film include vapor deposition polyester films such as vapor deposition polyethylene terephthalate films, vapor deposition polyamide films, and vapor deposition OPP films (vapor deposition biaxially oriented polypropylene).

[0127] A layer containing an ultraviolet absorber may be located between the barrier layer 44 and the first surface 31. The barrier layer 44 may deteriorate over time due to ultraviolet rays. Therefore, the layer containing the ultraviolet absorber can suppress the deterioration of the barrier layer 44 and maintain the gas barrier property of the barrier layer 44. In the example shown in FIG. 3C, one or more of the weather-resistant layer 42, the base material 41, and the second bonding layer 45 may contain an ultraviolet absorber.

[0128] The coating sheet 30 shown in FIG. 2C includes a barrier layer 44 and a weather-resistant layer 42 in this order from the second surface 32 toward the first surface 31. The barrier layer 44 is located between the steel material 20 and the weather-resistant layer 42 in the lamination direction. The gas barrier property of the barrier layer 44 is maintained by the weather-resistant layer 42 containing a weathering agent such as an ultraviolet absorber.

[0129] The oxygen transmission rate (OTR, unit: cc / (m 2 ·day·atm)) of the coating sheet 30 including the barrier layer 44 may be 3.0 or less, 2.5 or less, or 2.0 or less. According to the coating sheet 30 with the oxygen transmission rate adjusted in this way, corrosion of the steel material 20 and deterioration of the coating film can be suppressed. The lower the oxygen transmission rate of the coating sheet 30, the more preferable, but it may be 0.01 or more, 0.05 or more, or 0.1 or more.

[0130] The oxygen transmission rate is a value measured under the conditions of a temperature of 23°C and a relative humidity difference of 60%RH in accordance with JIS K7126-2:2006 "Appendix A (Provisions): Test Method for Oxygen Gas Transmission Rate by Electrolytic Sensor Method". The coating sheet 30 is installed in the measuring device so that the first surface 31 becomes the oxygen supply side. The measuring device for the oxygen transmission rate may be "OX-TRAN 2 / 20" manufactured by MOCON, USA.

[0131] The water vapor transmission rate (WVTR, unit: g / (m2·day)) of the coating sheet 30 including the barrier layer 44 may be 3.0 or less, may be 2.5 or less, or may be 2.0 or less. According to the coating sheet 30 with the water vapor transmission rate thus adjusted, corrosion of the steel material 20 and deterioration of the coating film can be suppressed. The lower the water vapor transmission rate of the coating sheet 30, the more preferable, but it may be 0.01 or more, may be 0.05 or more, or may be 0.1 or more.

[0132] The water vapor transmission rate is a value measured in an environment of a temperature of 40°C and a relative humidity difference of 90%RH in accordance with JIS K7129-2:2019. The coating sheet 30 is installed in the measuring device such that the first surface 31 becomes the hydrogen supply side. The measuring device for the water vapor transmission rate may be PERMATRAN-w 3 / 33 manufactured by MOCON, USA.

[0133] <Bonding layer> The bonding layer 43 and the second bonding layer 45 contain components having adhesiveness or tackiness. The bonding layer 43 bonds the coating sheet 30 to the steel material 20 or the coating film on the steel material 20. The second bonding layer 45 bonds the barrier layer 44 to the base material 41.

[0134] The bonding layer 43 and the second bonding layer 45 may be an adhesive layer or a tacky layer. Examples of the component having adhesiveness or tackiness include acrylic resin, vinyl chloride-vinyl acetate copolymer, vinyl acetate resin, polyolefin, polyester, polyurethane, silicone resin, and rubber-based resin.

[0135] The bonding layer 43 and the second bonding layer 45 may be a pressure-sensitive adhesive layer, that is, a tacky layer. The tacky layer is a layer formed by an adhesive (pressure-sensitive adhesive). The tacky layer exhibits a tacky feeling as a tack feeling at room temperature (for example, 23°C). Examples of the adhesive include acrylic adhesives, urethane adhesives, silicone adhesives, and rubber adhesives. The acrylic adhesive is preferably applied to the bonding layer 43 in terms of excellent adhesion to the steel material 20 having irregularities or the coating film on the steel material 20. The acrylic adhesive is also excellent in stability.

[0136] The bonding layer 43 and the second bonding layer 45 may contain additives. Examples of the additives include pigments, dyes, colorants, antistatic agents, flame retardants, fungicides, crosslinking agents, tackifiers, plasticizers, leveling agents, flow regulators, defoaming agents, and dispersants. The bonding layer 43 and the second bonding layer 45 may contain weathering agents such as ultraviolet absorbers, antioxidants, and light stabilizers.

[0137] The storage elastic modulus (G’) of the bonding layer 43 and the second bonding layer 45 at 40°C may be 0.05 MPa or more and 1 MPa or less, may be 0.05 MPa or more and 0.8 MPa or less, may be 0.1 MPa or more and 1 MPa or less, or may be 0.1 MPa or more and 0.8 MPa or less. When the storage elastic modulus is at least the lower limit value, excessive elongation of the adhesive layer when subjected to an impact can be suppressed. When the storage elastic modulus is at most the upper limit value, breakage of the adhesive layer when subjected to an impact can be suppressed.

[0138] The storage elastic modulus is measured by the following method. Two test pieces 90 are produced from the coating sheet 30 in accordance with the method for producing test pieces described in 6.2 of JIS K7244-1:1998. Since the test pieces 90 are produced from the coating sheet 30, the test pieces 90 include a support 91 corresponding to the portion of the coating sheet 30 other than the bonding layer 43 and an adhesive layer 92 corresponding to the bonding layer 43 of the coating sheet 30.

[0139] The method described herein can also measure the storage elastic modulus (G’) of the bonding layer 15 shown in Fig. 1B. In this example, the test piece 90 includes a support 91 corresponding to the coating sheet 30 and an adhesive layer 92 corresponding to the bonding layer 15.

[0140] Subsequently, the two produced test pieces 90 are attached to a measuring device 70 as shown in FIG. 3. As shown in FIG. 3, the measuring device 70 includes a plate 71 and a jig 72. The jig 72 includes a pair of plate-like portions 73 that sandwich the plate 71. The plate 71 and the pair of plate-like portions 73 extend in the vertical direction. The distance between the pair of plate-like portions 73 can be adjusted by rotating a nut 75 screwed onto a bolt 74 that passes through the pair of plate-like portions 73. The bolt 74 does not pass through the plate 71 and the test piece 90 attached to the measuring device 70. The bolt 74 is located at a position different from that of the plate 71 and the test piece 90 in a direction perpendicular to the plane of FIG. 3. When attaching the two test pieces 90 to the measuring device 70, first, due to the action of the adhesive layer 92, the two test pieces 90 are adhered to the plate 71 such that the plate 71 is sandwiched between the two test pieces 90. Subsequently, by rotating the nut 75 to reduce the distance between the pair of plate-like portions 73, as shown in FIG. 3, the plate 71 and the two test pieces 90 are sandwiched between the pair of plate-like portions 73. Thereby, the two test pieces 90 are fixed to the jig 72.

[0141] Also, the thickness w1 of the test piece 90 is specified. The thickness w1 of the test piece 90 can be specified by the following method. Before fixing two test pieces 90 to the jig 72, the dimensions of the plate 71 and the jig 72 are specified. As the dimensions of the plate 71 and the jig 72, the thickness w2 of the plate 71 shown in FIG. 3 and the thicknesses w3, w4 of each of the pair of plate-like portions 73 can be specified. The thicknesses w2, w3, w4 can be specified by measuring with a caliper. Further, after fixing two test pieces 90 to the jig 72 as shown in FIG. 3, the dimensions of the jig 72 in the state where the two test pieces 90 are sandwiched are specified. As the dimension of the jig 72 in the state where the two test pieces 90 are sandwiched, the distance w5 from one outer surface of the pair of plate-like portions 73 to the other outer surface of the pair of plate-like portions 73 shown in FIG. 3 can be specified. The distance w5 can be specified by measuring with a caliper. Subsequently, the thickness w1 of the test piece 90 is specified from the dimensions of the plate 71 and the jig 72 and the dimensions of the jig 72 in the state where the two test pieces 90 are sandwiched. The thickness w1 of the test piece 90 can be calculated by subtracting the thicknesses w2, w3, w4 from the distance w5 and dividing by 2. The specified thickness w1 of the test piece 90 is used for the measurement of the storage elastic modulus (G').

[0142] After fixing two test pieces 90 to the jig 72 as shown in FIG. 3, the jig 72 is vibrated in the vertical direction. As a result, vertical vibration is input to the adhesive layer 92 of the test piece 90. By detecting the movement of the plate 71 when vertical vibration is input to the adhesive layer 92 of the test piece 90, the storage elastic modulus (G') of the adhesive layer 92 can be measured.

[0143] The measurement of the storage elastic modulus (G') is performed under the following conditions. · Atmosphere gas: Nitrogen · Attachment mode: Solid shear mode · Temperature dependence · Fundamental frequency: 10 Hz · Measurement program: Start temperature = 30 °C, Step temperature = 1 °C, End temperature = 150 °C, Heating rate: 3 °C / min) · Sine wave, Stop excitation · Manual static load: Adjusted to be 0 g when fixing two test pieces 90 to the jig 72 ·Warp: The value automatically set when inputting the sample length, 0.05, automatic adjustment mode

[0144] The measurement of the storage modulus of elasticity (G’) can be carried out using a solid viscoelasticity measuring device. As the solid viscoelasticity measuring device, Rheogel E4000 manufactured by UBM Co., Ltd. can be used.

[0145] The thicknesses of the bonding layer 43 and the second bonding layer 45 may be 10 μm or more, 20 μm or more, 30 μm or more, 40 μm or more, or 50 μm or more. The thicknesses of the bonding layer 43 and the second bonding layer 45 may be 1000 μm or less, 500 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, 180 μm or less, or 150 μm or less.

[0146] <Other layers that may be included in the coating sheet> Not limited to the examples shown in FIGS. 2A to 2C, the coating sheet 30 may further include additional layers.

[0147] As an example, as shown by the dashed-dotted line in FIG. 2C, the coating sheet 30 may further include a release film 46. Before bonding the coating sheet 30 to the steel material 20, the release film 46 is bonded to the bonding layer 43. According to the release film 46, the bonding layer 43 can be protected from foreign matters such as dust before the use of the coating sheet 30. When using the coating sheet 30, the release film 46 is removed from the coating sheet 30. By removing the release film 46, the bonding layer 43 is exposed, and the coating sheet 30 can be bonded to the steel material 20. Examples of the release film 46 include a paper substrate and a resin film, and those with a release agent applied to their surfaces. Examples of the release agent include silicone-based release agents, fluorine-based release agents, and long-chain alkyl-based release agents.

[0148] <<<Other layers that may be included in the steel structure>>> The steel structure 10 shown in FIG. 1B further includes a third bonding layer 15 in addition to the steel material 20 and the coating sheet 30. The steel structure 10 shown in FIG. 1C further includes a rust preventive layer 18. Also, as shown by the two-dot chain line in FIG. 1C, the steel structure 10 may include a topcoat layer 19. Not limited to the examples shown in FIGS. 1A to 1C, the steel structure 10 may include further layers.

[0149] <<Bonding layer (third bonding layer)>> As shown in FIG. 1B, the third bonding layer 15 is used to bond the coating sheet 30 to the steel material 20. The third bonding layer 15 may be configured in the same manner as the bonding layer 43 of the coating sheet 30 described above.

[0150] <<Rust preventive layer>> The rust preventive layer 18 is located between the steel material 20 and the coating sheet 30. The rust preventive layer 18 suppresses the corrosion of the steel material 20. The rust preventive layer 18 suppresses the spread of corrosion in the steel material 20. As shown in FIGS. 1A and 1B, the rust preventive layer 18 can be omitted from the steel material 20.

[0151] The rust preventive layer 18 may be produced by forming a coating film by applying a rust preventive paint containing a rust preventive agent on the surface of the steel material 20 and solidifying or curing this coating film. Examples of the painting method include brush painting, roller painting, and spray painting (for example, air spray, airless spray). The rust preventive layer 18 formed as a coating film can improve the adhesion to the uneven surface of the steel material 20.

[0152] The thickness of the rust preventive layer 18 may be 10 μm or more, 30 μm or more, 50 μm or more, 100 μm or more, or 150 μm or more. The thickness of the rust preventive layer 18 may be 1000 μm or less, 800 μm or less, 600 μm or less, or 500 μm or less. By setting a lower limit value for the thickness of the rust preventive layer 18, a sufficient rust preventive function can be imparted to the rust preventive layer 18. By setting an upper limit value for the thickness of the rust preventive layer 18, it is excellent in workability and cost when producing the rust preventive layer 18.

[0153] Examples of the rust inhibitor contained in the rust prevention layer 18 include inorganic rust inhibitors and organic rust inhibitors. The inorganic rust inhibitor may be an inorganic acid or a salt of an inorganic acid. Examples of the inorganic rust inhibitor include red lead, lead oxide, basic lead chromate, diamide lead, calcium plumbate, basic lead sulfate, zinc chromate, zinc powder, valve handle, nitrite, sulfite, silicate, metasilicate, phosphate, polyphosphate, hypophosphite, phosphite, molybdate, phosphomolybdate, borate, metaborate, tungstate, carbonate, and chromate. Examples of the inorganic rust inhibitor include phosphate compounds, vanadium compounds, niobium compounds, zirconium compounds, and zinc oxide. Examples of the inorganic rust inhibitor include ammonium salts, calcium salts, magnesium salts, aluminum salts, zinc salts, manganese salts, and barium salts.

[0154] Examples of the organic rust inhibitor include organic amine compounds, organic amine salts, tannic acid, carboxylic acids, and esters or salts of these acids. Examples of the organic rust inhibitor include sulfonates, organic phosphates, benzotriazole compounds, benzothiazole compounds, mercaptan compounds, guanidino group-containing compounds, piguanidino group-containing compounds, thiocarbonyl group-containing compounds, alkylphenol compounds, diisopropylammonium nitrite, and dicyclohexylammonium nitrite.

[0155] Examples of the rust prevention paint include epoxy resin paint, urethane resin paint, acrylic resin paint, silicone acrylic resin paint, styrene resin paint, fluororesin paint, and zinc-rich paint containing an organic binder and zinc powder. The rust prevention paint may contain a binder and a rust inhibitor. Examples of the binder of the rust prevention paint include organic binders such as epoxy resin, urethane resin, acrylic resin, silicone acrylic resin, styrene resin, and fluororesin. Examples of the binder of the rust prevention paint include inorganic binders such as alkyl silicate.

[0156] From the perspective of the rust prevention mechanism, the rust prevention layer can be classified into a rust conversion type and a salt / iron ion detoxification type. The rust prevention layer 18 may be of the rust conversion type or the salt / iron ion detoxification type.

[0157] The rust prevention paint may be a one-component curable rust prevention paint or a two-component curable rust prevention paint containing a main agent and a curing agent. The two-component curable rust prevention paint stores the main agent containing a binder and, if desired, a rust inhibitor, and the curing agent that promotes the cross-linking reaction in separate containers, and the two may be mixed immediately before use. The two-component curable rust prevention paint is excellent in that it has high adhesion to the steel material 20, high coating film strength, and can form a dense rust prevention layer 18. The two-component curable rust prevention paint also has excellent adhesion to the coating sheet 30. The two-component curable rust prevention paint may be a two-component curable epoxy resin paint, a two-component curable urethane resin paint, or a two-component curable epoxy resin paint.

[0158] The two-component curable epoxy resin paint may contain an epoxy resin as a binder and a curing agent for the epoxy resin as a curing agent. Examples of the curing agent include amine-based curing agents, phenol-based curing agents, acid anhydride-based curing agents, and mercaptan-based curing agents. The urethane resin paint may be a two-component curable type composed of a polyol-based compound and an isocyanate-based compound, or a one-component curable type that cures by moisture in the air or the like.

[0159] The rust prevention paint may contain additives. Examples of the additives include rosins, plasticizers, extender pigments, coloring pigments, solvents, curing accelerators, coupling agents, corrosive ion immobilizing agents, anti-sagging agents, and anti-settling agents. Examples of the coupling agent include silane-based coupling agents, titanium-based coupling agents, aluminum-based coupling agents, and zirconium-based coupling agents. Examples of the corrosive ion immobilizing agent include hydrotalcite and hydrocalumite.

[0160] On the surface of the rust prevention layer 18 provided on the steel material 20, the specular glossiness at 85 degrees may be 3 or more. The specular glossiness at 85 degrees on the surface of the rust prevention layer 18 may be 5 or more, 10 or more, 15 or more, 20 or more, or 23 or more. By setting the lower limit of the specular glossiness at 85 degrees on the surface of the rust prevention layer 18 in this way, the rust prevention layer 18 becomes a dense film. The rust prevention layer 18 as a dense film exhibits high adhesion to the coating sheet 30. The upper limit value of the specular glossiness at 85 degrees on the surface of the rust prevention layer 18 is not particularly limited. The specular glossiness at 85 degrees on the surface of the rust prevention layer 18 may be 60 or less, 50 or less, or 40 or less.

[0161] The specular glossiness is a value measured in accordance with JIS Z8741:1997, except that the incident angle is set to 85°. The measurement environment when measuring the specular glossiness is a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. The measurement sample to be measured is placed in the measurement environment for 16 hours before the start of measurement. Before measuring the specular glossiness, the light source of the measuring device is turned on for 15 minutes to stabilize the output of the light source.

[0162] The specular glossiness is the arithmetic mean value of five measured values. The five measured values are the measured values measured at five measurement positions on the measurement sample to be evaluated. The five measurement positions are located at least 10 mm apart from each other.

[0163] Regarding the rust prevention layer 18 provided on the steel material 20, a lower limit may be set for the retention rate of the specular glossiness at 85 degrees. By setting a lower limit for the retention rate of the specular glossiness at 85 degrees on the surface of the rust prevention layer 18, the adhesion of the rust prevention layer 18 to the steel material 20 can be ensured. The retention rate of the specular glossiness at 85 degrees on the surface of the rust prevention layer 18 may be 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more.

[0164] The retention rate of 85-degree specular gloss is the retention rate of the 85-degree specular gloss on the surface of the rust preventive layer 18 before and after performing the 90-degree tape peeling test. Let the 85-degree specular gloss on the surface of the rust preventive layer 18 before performing the 90-degree tape peeling test on the rust preventive layer 18 be "Gsb". Let the 85-degree specular gloss on the surface of the rust preventive layer 18 after performing the 90-degree tape peeling test on the rust preventive layer 18 be "Gsa". The retention rate of the 85-degree specular gloss is represented by Gsa×100 / Gsb, and the unit is %.

[0165] The 90-degree tape peeling test is carried out as follows. Unroll 25 cm from a roll of 24 mm wide cellophane adhesive tape conforming to JIS Z1522:2009, and in an environment of temperature 23°C ± 2°C and relative humidity 50% ± 5%, stick the 10 cm adhesive surfaces together to make a handle, then attach 5 cm of the adhesive surface to the rust preventive coating surface of the steel structure with a 2 kg pressure roller reciprocating twice, and then attach it again by finger pressure so that no air intervenes. Then, manually perform a single strong peeling of the cellophane adhesive tape at a speed of 5 cm / s in a 90-degree direction with respect to the rust preventive coating surface. As the above cellophane adhesive tape, Cellotape (registered trademark) (manufactured by Nichiban, model number No. 405-1P, 24 mm wide) is used. When this product cannot be used, a 24 mm wide cellophane adhesive tape conforming to JIS Z1522:2009 and having an adhesive force equivalent to that of this product is used.

[0166] <<Topcoat layer>> The topcoat layer 19 is formed on the covering sheet 30. In this example, the covering sheet 30 is located between the topcoat layer 19 and the steel material 20 in the stacking direction. The topcoat layer 19 may be provided for the purpose of improving the weather resistance of the steel structure 10. The topcoat layer 19 may impart excellent rust prevention properties to the steel structure 10 over a long period. The topcoat layer 19 can be omitted from the steel structure 10.

[0167] The topcoat layer 19 may be produced by applying a topcoat paint to the first surface 31 of the coating sheet 30 to form a coating film and then solidifying or curing this coating film. Examples of the coating method include brush coating, roller coating, and spray coating (e.g., air spray, airless spray). The topcoat paint may be a one-component paint or a two-component paint. The topcoat layer 19 and the topcoat paint may contain a resin and additives.

[0168] Examples of the resin contained in the topcoat layer 19 and the topcoat paint include fluororesin, urethane resin, acrylic resin, butadiene resin, silicone resin, vinyl ester resin, and epoxy resin. Examples of the fluororesin include polyvinyl fluoride, polytetrafluoroethylene, perfluoroalkoxy alkane, and ethylene-tetrafluoroethylene copolymer. Examples of the additives contained in the topcoat layer 19 and the topcoat paint include pigments, dyes, dispersants, defoamers, thickeners, leveling agents, anti-settling agents, anti-drip agents, algaecides, fungicides, preservatives, ultraviolet absorbers, antioxidants, and light stabilizers, etc.

[0169] The topcoat paint may contain an organic solvent and / or water for the purpose of adjusting the viscosity, etc. Examples of the organic solvent include aromatic hydrocarbons, aliphatic hydrocarbons, ketones, acetic esters, ethers, alcohol-based solvents, and mineral spirits.

[0170] The thickness of the topcoat layer 19 may be 5 μm or more, 10 μm or more, or 15 μm or more. The thickness of the topcoat layer 19 may be 200 μm or less, 150 μm or less, or 100 μm or less.

[0171] Next, a method for repairing the steel structure 10 using the coating sheet 30 will be described.

[0172] As described above, according to the coating sheet 30, inspection of the steel structure 10, which is a prerequisite for preventive maintenance, can be facilitated. By having a combination of the above-described features (A) to (C) and the like, the state of the steel material 20 can be observed through the coating sheet 30. Therefore, abnormalities that may occur in the steel material 20 covered by the coating sheet 30 can be easily and stably detected from the initial stage. According to this coating sheet 30, as will be described below, not only can the inspection of the steel structure 10 be facilitated, but also the construction of preventive maintenance can be facilitated.

[0173] As an example, the steel structure 10 to be repaired may be a steel structure 10 including a coating sheet 30 as shown in FIGS. 1A to 1C. As another example shown in FIG. 5, the steel structure 10 to be repaired may be a steel structure 100 including a steel material 20 and a number of coating films 50 formed on the steel material 20.

[0174] FIG. 5 shows a conventional steel structure 100 including a number of coating films 50. The coating films 50 included in the steel structure 100 include, in order from the steel material 20, a rust preventive layer 51, a first undercoat layer 52, a second undercoat layer 53, a middle coat layer 54, and a top coat layer 55.

[0175] The rust preventive layer 51 has a rust preventive function. The rust preventive layer 51 is a layer that suppresses rusting and the spread of rust. The rust preventive layer 51 may be configured in the same manner as the above-described rust preventive layer 18.

[0176] The first undercoat layer 52 and the second undercoat layer 53 have gas barrier properties. The first undercoat layer 52 and the second undercoat layer 53 suppress corrosion of the steel material 20. The barrier property of a barrier layer that is a coating film is weaker than that of a barrier layer that is a vapor deposition film. In the illustrated steel structure 100, in order to ensure sufficient barrier properties, two undercoat layers 52 and 53 are included. The undercoat layers 52 and 53 may include an epoxy resin. The undercoat layers 52 and 53 may include a cured product of a curable resin.

[0177] The intermediate coat layer 54 has easy adhesiveness. The intermediate coat layer 54 improves the adhesion of the top coat layer 55. As an intermediate coat layer having easy adhesiveness, a layer containing a fluororesin is exemplified. The intermediate coat layer 54 may contain weathering agents such as an ultraviolet absorber, an antioxidant, and a light stabilizer.

[0178] The top coat layer 55 has weather resistance. The top coat layer 55 contains weathering agents such as an ultraviolet absorber, an antioxidant, and a light stabilizer. As the top coat layer 55, a layer containing a fluororesin and a weathering agent is exemplified. The top coat layer 55 may be configured in the same manner as the above-described top coat layer 19.

[0179] Each of the multiple coating films 50 is produced at a rate of one layer per day, taking into account the time for drying, solidifying, and curing. For example, the steel structure 100 shown in FIG. 5 requires a construction period of 5 days.

[0180] With reference to FIGS. 4A to 4D, a repair method for the steel structure 100 shown in FIG. 5 will be described. A coating sheet 30 is used for the repair. The repaired steel structure 10 includes the coating sheet 30. Without being limited to the example shown in FIGS. 4A to 4D, the steel structure 10 including the coating sheet 30 may be repaired using the coating sheet 30.

[0181] The repair method shown in FIGS. 4A to 4D includes a first step, a second step, a third step, and a fourth step. In the first step, the coating sheet 30 is prepared. In the second step shown in FIG. 4B, the substrate of the deteriorated portion 12 of the steel structure is adjusted. In the third step shown in FIG. 4C, the rust preventive layer 18 is formed. In the fourth step shown in FIG. 4D, the coating sheet 30 is joined to the steel material 20. Hereinafter, each step will be described in order.

[0182] FIG. 4A is a cross-sectional view schematically showing the deteriorated portion 12 of the steel structure. In FIG. 4A, a pre-repair coating film (old coating film) 50 is provided on the steel material 20. Rust 60 has occurred on the steel material 20. To repair such a deteriorated portion 12, as the first step, the above-described coating sheet 30 is prepared.

[0183] As shown in FIG. 4B, in the second step, substrate adjustment (base adjustment) is performed on the deteriorated portion 12 of the steel structure 100. As a method for adjusting the substrate of the steel structure 100, scarifying treatment is exemplified. In scarifying treatment, generally, blast treatment, power tools or hand tools are used to remove old paint films, rust, dust, dirt, etc. By the removal, the substrate adjustment surface 22 is exposed. In the second step, the substrate adjustment surface 22 constitutes the surface of the steel structure 100.

[0184] Scarifying treatment has grades of single - type scarifying, double - type scarifying, triple - type scarifying, and quadruple - type scarifying. The smaller the grade number, the higher the level of substrate adjustment.

[0185] "Single - type scarifying" is substrate adjustment that removes all rust and old paint film 50 to expose the steel material surface. In "single - type scarifying", substrate adjustment is mainly performed by blast treatment.

[0186] "Double - type scarifying" is substrate adjustment that removes rust and old paint film 50 to expose the surface of the steel material 20. In "double - type scarifying", substrate adjustment is mainly performed by power tools and / or hand tools.

[0187] "Triple - type scarifying" is substrate adjustment that removes defective parts (rust and dead films (films with cracks and bulges) among old paint films) of the old paint film 50 but leaves the live film 50P, that is, the paint film in a sound state. In "triple - type scarifying", substrate adjustment is mainly performed by power tools and / or hand tools.

[0188] Triple - type scarifying has the advantages that the working area is smaller and the working cost is lower than those of single - type scarifying and double - type scarifying. Since the live film 50P of the old paint film 50 remains, the substrate adjustment surface after triple - type scarifying may have large irregularities. Rust surfaces may remain on the substrate adjustment surface after triple - type scarifying. The height of the irregularities on the surface of the steel structure 10 after triple - type scarifying may be 10 μm or more and 1000 μm or less, may be 30 μm or more and 500 μm or less, or may be 50 μm or more and 300 μm or less.

[0189] Figure 4B shows the steel structure 100 whose substrate has been adjusted using three types of keren. In Figure 4B, the old coating film 50 has been removed except for the active film 50P. In Figure 4B, the rust 60 has also been removed.

[0190] The "four types of keren" is substrate adjustment for removing powder deposits (including loose rust) and dirt etc. adhering to the surface. In the "four types of keren", substrate adjustment is mainly carried out using manual tools and / or brushes.

[0191] Examples of power tools include a disk sander and a wire wheel. Examples of manual tools include a wire brush, a scraper, a keren bar, and sandpaper.

[0192] In the third step, as shown in Figure 4C, rust prevention treatment is performed on the substrate adjustment surface 22 of the steel structure 100. By the third step, a rust prevention layer 18 is formed on the steel material 20 and the active film 50P. The material and formation method of the rust prevention layer 18 are as described above.

[0193] The rust prevention layer 18 contains a rust inhibitor. The rust inhibitor can suppress rusting. The rust inhibitor may be included in the bonding layer 15 or the coating sheet 30 (for example, the bonding layer 43). By separately providing the rust prevention layer 18 containing the rust inhibitor from the coating sheet 30, the effect of the rust inhibitor can be obtained more clearly. The rust prevention layer 18 formed as a coating film can fill the irregularities of the substrate adjustment surface having irregularities to a certain extent. Thereby, the adhesion of the coating sheet 30 can be improved.

[0194] In the fourth step, the coating sheet 30 is arranged on the steel structure 100 being repaired. In the example shown in Figure 4D, the coating sheet 30 is arranged on the rust prevention layer 18. The coating sheet 30 including the bonding layer 43 is bonded to the rust prevention layer 18 using the bonding layer 43. In the example shown in Figure 4D, the bonding layer 15 is formed on the rust prevention layer 18, and the coating sheet 30 is bonded to the rust prevention layer 18 using this bonding layer 15. By the fourth step, the steel structure 10 including the coating sheet 30 is obtained.

[0195] The covering sheet 30 may be attached to the steel structure 10 by the bonding layers 15 and 43 while being pressed at room temperature. For example, the covering sheet 30 may be pushed toward the steel material 20 from above the covering sheet 30 using a roller or the like. Thereby, the covering sheet 30 and the steel material 20 or the coating film (for example, the rust preventive layer 18) on the steel material 20 can be brought into close contact with each other.

[0196] When the covering sheet 30 includes the release film 46, the release film 46 is peeled off from the covering sheet 30 before the covering sheet 30 is disposed on the steel material 20. By peeling off the release film 46, the bonding layer 43 is exposed.

[0197] The covering sheet 30 may cover the side end portion of the rust preventive layer 18. The covering sheet 30 may be bent to cover the side end surface of the steel structure 10.

[0198] As described above, the steel structure is repaired using the covering sheet 30, and the steel structure 10 including the covering sheet 30 is obtained. According to the repair using the covering sheet 30, the repair of the steel structure can be performed in a short period. For example, compared with reforming a large number of coating films 50 shown in FIG. 5 at the repair location, the construction period can be significantly shortened by using the covering sheet 30. Further, the repair using the covering sheet 30 can reduce costs and facilitate construction. Furthermore, by using the covering sheet 30 manufactured in a factory with an improved environment, the occurrence of defects such as pinholes can be suppressed compared with forming a large number of coating films on the steel material 20 outdoors. As described above, by using the covering sheet 30, preventive maintenance can be facilitated. The steel structure 10 including the covering sheet 30 obtained by the repair can facilitate inspection for the purpose of detecting abnormalities.

[0199] The method for repairing a steel structure using the covering sheet 30 is not limited to the above-described method described with reference to FIGS. 4A to 4D.

[0200] In the illustrated example, three types of surface preparations are carried out as the surface preparation in the second step. However, the repair method using the coating sheet 30 is not limited to this example. For steel structures in which one type of surface preparation, two types of surface preparations, or four types of surface preparations other than the three types of surface preparations are carried out as the surface preparation, the repair method using the coating sheet 30 can be applied.

[0201] Before the fourth step is carried out, a step of forming a flattening layer may be carried out. The flattening layer may be formed on the surface preparation surface 22 or on the rust prevention layer 18. By providing the flattening layer, the surface to which the coating sheet 30 is joined is flattened. Thereby, the adhesion of the coating sheet 30 to the steel structure 10 can be improved.

[0202] Examples of the material constituting the flattening layer include fluororesin, acrylic resin, silicone resin, urethane resin, urea resin, and epoxy resin. The flattening layer may be produced by applying a paint to form a coating film and solidifying or curing this coating film. The paint may be a one-component curable paint or a two-component curable paint. The flattening layer may contain additives such as an ultraviolet absorber, an antioxidant, and a light stabilizer.

[0203] The third step may be omitted from the above-described repair method. When the third step is omitted, the coating sheet 30 is joined to the surface preparation surface 22. Further, the above-described repair method may include a step of producing a topcoat layer 19.

[0204] As already mentioned, the steel structure 10 including the coating sheet 30 is not limited to the example shown in FIGS. 4A to 4D, and may be repaired using the coating sheet 30.

Example

[0205] The present disclosure will be described in more detail by way of examples. The present disclosure is not limited by the following examples.

[0206] <<<1. Production of coating sheet>>> Coating sheets according to Examples 1 to 2 and Comparative Examples 1 to 4 were produced.

[0207] <<Example 1>> As the coated sheet according to Example 1, a coated sheet including a base material, a primer layer, and a weather-resistant layer in this order was produced.

[0208] The base material was obtained by forming a resin composition into a sheet. The resin composition was obtained by mixing 5 parts by mass of a weathering agent masterbatch with respect to 95 parts by mass of a base resin.

[0209] The base resin was a metallocene linear low-density polyethylene-based resin (M-LLDPE). The density of the base resin was 0.901 g / cm 3 . The melting point of the base resin was 93°C. The MFR (melt flow rate) of the base resin at 190°C was 2.0 g / 10 min.

[0210] The weathering agent masterbatch was obtained by mixing 100 parts by mass of a low-density polyethylene-based resin, 0.6 parts by mass of HALS, 3.5 parts by mass of a first ultraviolet absorber, and 0.6 parts by mass of a second ultraviolet absorber. The density of the low-density polyethylene-based resin was 0.880 g / cm 3 . The MFR (melt flow rate) of the low-density polyethylene-based resin at 190°C was 3.5 g / 10 min. HALS was "KEMISTAB62" manufactured by Chemipro Kasei Co., Ltd. The first ultraviolet absorber was "KEMISORB12" manufactured by Chemipro Kasei Co., Ltd. The second ultraviolet absorber was "KEMISORB79" manufactured by Chemipro Kasei Co., Ltd.

[0211] For forming the resin composition into a sheet, a φ30 mm extruder and a film forming machine having a 200 mm wide T-die were used. In the extrusion process by the extruder, the extrusion temperature was 210°C. The take-up speed of the extruded sheet was adjusted so that the thickness of the produced base material became 300 μm. The cooling roll directly below the T-die was chrome-plated. The surface roughness Rz of the cooling roll was 1.5 μm. As the rubber roll directly below the T-die, a silicone rubber roll was used. The hardness of the silicone rubber roll was 70 degrees.

[0212] As described above, a transparent substrate with a thickness of 300 μm and not directly colored was obtained.

[0213] Next, one surface of the substrate was subjected to corona discharge treatment. Thereafter, a primer layer was formed on the corona discharge-treated surface of the substrate using a resin composition for the primer layer.

[0214] The resin composition for the primer layer was prepared by mixing 100 parts by mass of a mixture, 5 parts by mass of a curing agent, 20 parts by mass of an ultraviolet absorber, and a diluting solvent. The 100 parts by mass of the mixture was a mixture composed of a polycarbonate-based urethane-acrylic copolymer and an acrylic polyol. The 5 parts by mass of the curing agent was hexamethylene diisocyanate.

[0215] The resin composition for the primer layer was applied to the treated surface of the substrate subjected to corona discharge treatment by the gravure printing method. The primer layer was obtained by drying the coating film of the resin composition for the primer layer formed on the substrate. The thickness of the primer layer was 4 μm.

[0216] Next, a weather-resistant layer was formed on the primer layer using an ionizing radiation curable resin composition. The ionizing radiation curable resin composition was prepared by mixing 100 parts by mass of a urethane acrylate oligomer, 4 parts of a hydroxyphenyltriazine-based ultraviolet absorber as an ultraviolet absorber, and 3 parts by mass of a hindered amine-based non-reactive light stabilizer. The prepared ionizing radiation curable resin composition was applied onto the primer layer to form an uncured resin layer on the primer layer.

[0217] Thereafter, the uncured resin layer was cured by irradiating the uncured resin layer with an electron beam. As the irradiation conditions of the electron beam, the acceleration voltage was 165 kV and the irradiation dose was 5 Mrad (50 kGy). By irradiating the uncured resin layer with the electron beam, a weather-resistant layer with a thickness of 5 μm was formed. The weather-resistant layer and the substrate were joined via a primer layer not shown in FIG. 2B.

[0218] As described above, a coated sheet according to Example 1 including a base material, a primer layer, and a weather-resistant layer in this order was obtained.

[0219] <<Example 2>> As a coated sheet according to Example 2, a coated sheet including a barrier layer, a second bonding layer, a base material, a primer layer, and a weather-resistant layer in this order was produced. Example 2 was different from Example 1 in that a barrier layer joined to the base material using the second bonding layer was provided, and was the same as Example 1 in other respects. That is, the base material, primer layer, and weather-resistant layer of the coated sheet according to Example 2 were the same as the base material, primer layer, and weather-resistant layer of the coated sheet according to Example 1, respectively. The coated sheet according to Example 2 was produced by forming a barrier layer and a second bonding layer on the coated sheet according to Example 1. The formation methods of the barrier layer and the second bonding layer are as follows.

[0220] A transparent urethane resin-based adhesive was applied to the surface of the base material opposite to the surface on which the primer layer and the weather-resistant layer were laminated. By drying the coating film of the urethane resin-based adhesive on the base material, a second bonding layer with a thickness of 3 μm was formed.

[0221] Next, as a gas barrier film including a barrier layer, IB-PET-UB available from Dai Nippon Printing Co., Ltd. was prepared. IB-PET-UB included a resin film and a gas barrier layer which was a vapor deposition film. The base material and the gas barrier film were joined by dry lamination using the above-described second bonding layer. The gas barrier layer of the gas barrier film was brought into contact with and joined to the second bonding layer.

[0222] <<Comparative Example 1>> As a coated sheet according to Comparative Example 1, a coated sheet including a base material and a resin layer was produced. The base material used was the same base material as that of Example 1 produced by the same method as Example 1 using the same material as Example 1. One surface of the base material was subjected to corona treatment in the same manner as in Example 1.

[0223] The resin layer was prepared using the paint "V Freon #100H Smile Topcoat" available from Dainippon Paint Co., Ltd. This paint was applied to the corona-treated surface of the substrate to form a coating film. By drying the coating film, a resin layer with a thickness of 5 μm was formed. The paint "V Freon #100H Smile Topcoat" is a colored paint used for forming the coating film that constitutes the outermost layer of the steel structure.

[0224] Thus, a coated sheet according to Comparative Example 1 including the substrate and the resin layer in this order was obtained.

[0225] <<Comparative Example 2>> As the coated sheet according to Comparative Example 2, "HBS006H" available from Mitsubishi Chemical Corporation was used. "HBS006H" is an acrylic film containing an ultraviolet absorber.

[0226] <<Comparative Example 3>> The coated sheet according to Comparative Example 3 was a laminate formed by laminating three sheets of white PET available from VANRA.

[0227] <<Comparative Example 4>> The coated sheet according to Comparative Example 4 was a polyethylene sheet used for the bag "FG-4" with a chuck of Japanax Co., Ltd.

[0228] <<<2. Measurement and Evaluation>>> Next, as described below, the coated sheets according to the examples and comparative examples were measured and evaluated. The test environment for the measurement and evaluation was set at a temperature of 23°C ± 2°C and a relative humidity of 50% ± 5%. Before starting the measurement and evaluation, the target samples were placed in the above test environment for 16 hours. Also, it was visually confirmed that there were no abnormalities such as dust or scratches on the samples used for the measurement and evaluation.

[0229] <<2-1. Total Light Transmittance>> Samples of 5 cm × 5 cm were cut out from the coating sheets according to the examples and comparative examples. The total light transmittance (%) of the coating sheets according to each example was measured by the method described above. For the measurement of the total light transmittance, a haze meter "HM-150L2N" manufactured by Murakami Color Research Laboratory was used. The measurement results of the total light transmittance are shown in "Tt" of Table 1.

[0230] <<2-2. Image sharpness by reflection method>> Samples of 5 cm × 5 cm were cut out from the coating sheets according to the examples and comparative examples. The image sharpness by the reflection method was measured for the coating sheets according to each example by the method described above. For the measurement of the image sharpness, an appearance analyzer "Rhopoint IQ S 20 / 60 / 85°" manufactured by Konica Minolta was used. The measurement results of the image sharpness are shown in the column of "DOI" in Table 1.

[0231] <<2-3. Spectral transmittance>> Samples of 5 cm × 5 cm were cut out from the coating sheets according to the examples and comparative examples. The spectral transmittance at each wavelength of 1 nm within the range of 300 nm or more and 350 nm or less was measured for the coating sheets according to each example by the method described above. For the measurement of the spectral transmittance, an ultraviolet-visible-near-infrared spectrophotometer "UH4150" manufactured by Hitachi High-Tech Corporation was used. The maximum transmittance at wavelengths of 300 nm or more and 350 nm or less is shown in the column of "Spectral transmittance" in Table 1.

[0232] <<2-4. Haze>> Samples of 5 cm × 5 cm were cut out from the anti-glare sheets according to the examples and comparative examples. The haze (%) of the coating sheets according to each example was measured by the method described above. For the measurement of the haze, a haze meter "HM-150L2N" manufactured by Murakami Color Research Laboratory was used. The measurement results of the haze are shown in the column of "Hz" in Table 1.

[0233] <<2-5. Sensory evaluation of visibility>> Samples measuring 5 cm × 5 cm were cut out from the coated sheets according to the examples and comparative examples. The samples of each example were placed on a steel plate with an "X" mark inscribed on its surface, and the visibility of the "X" mark on the steel plate was evaluated. The steel plate was a sandblasted plate manufactured by TP Giken. The sandblasted plate was SS400 sandblasted on both sides. SS400 was a structural steel plate compliant with JIS C3101. In the sandblasting process, the surface roughness Rz of SS400 was targeted at 25 μm. The surface roughness Rz was the surface roughness Rz compliant with JIS B 0601:2013. The "X" mark was 1 cm × 1 cm in size. The "X" mark was inscribed using the "thin" type of black oil-based magic marker "Macky Ultra Fine" manufactured by ZEBRA.

[0234] Under a bright room environment where the lighting device was lit, it was confirmed whether the "X" mark on the steel plate could be observed through the coated sheet of each example. The evaluation sample including the steel plate and the coated sheet of each example was flat. The evaluation sample was observed while slowly changing its orientation within a 90° angular range from a state where the normal of the evaluation sample was along the vertical direction to being inclined with respect to the vertical direction and along the horizontal direction. The lighting device was installed at a position above the evaluation sample in the vertical direction. The position of the evaluator's face was set to face the evaluation sample from the horizontal direction. Regardless of the orientation of the evaluation sample, the position of the evaluator's face was fixed. The lighting device was an Hf32-shaped straight tube three-wavelength daylight white fluorescent lamp. The illuminance on the evaluation sample directed to spread horizontally was 600 lux or more and 800 lux or less. The evaluators were 20 healthy persons in their 30s with a visual acuity of 0.7 or more.

[0235] The results of the evaluation according to the following evaluation criteria are shown in the "Visibility" column of Table 1. A: Fifteen or more of the 20 evaluators were able to continuously observe the "X" mark throughout the period during which the evaluation sample was tilted. B: Fifteen or more of the 20 evaluators were unable to observe the "X" mark during a part of the period during which the evaluation sample was tilted. BB: Fifteen or more of the 20 evaluators were unable to observe the "X" mark throughout the period during which the evaluation sample was tilted.

[0236] <<2-6. Weather Resistance Test>> Samples of 3 cm × 3 cm were cut out from the coating sheets according to the examples and comparative examples. The above-mentioned 408-hour weather resistance test was carried out on the evaluation samples of each example. The weather resistance test was carried out under the following conditions.

[0237] Taking 20 hours of irradiation process and 4 hours of dew condensation process as one cycle, the cycle was repeated until 408 hours were reached, and the evaluation samples were exposed to the irradiation process and the dew condensation process. A 30-second shower process was carried out before starting the dew condensation process after the irradiation process and before starting the irradiation process after the dew condensation process. In the shower process, the evaluation samples held in the weather resistance test device were showered with water.

[0238] As the weather resistance test device, the super-accelerated weather resistance test device "Eye Super UV Tester SUV-W261" manufactured by Iwasaki Electric Co., Ltd. was used. The UV lamp, lamp jacket, and illuminometer included in the weather resistance test device were as follows. · UV lamp: Product name: M04-L21WB / SUV, manufactured by Iwasaki Electric Co., Ltd. · Lamp jacket: Product name: WJ50-SUV, manufactured by Iwasaki Electric Co., Ltd. · Illuminometer: Product name: UVD-365PD, manufactured by Iwasaki Electric Co., Ltd.

[0239] The conditions of the irradiation process were as follows. <Irradiation Conditions> · Black panel temperature: 63°C · Illuminance: 100 mW / cm 2 · Humidity in the tank: 50% RH · Time: 20 hours

[0240] The conditions of the dew condensation process were as follows. <Irradiation Conditions> · Black panel temperature: 30°C · Illuminance: 0 mW / cm 2 · Humidity in the tank: 98% RH · Time: 4 hours

[0241] After the 408-hour weather resistance test, the total light transmittance (%), image sharpness (%) by the reflection method, and the maximum spectral transmittance (%) at wavelengths of 300 nm or more and 350 nm or less were measured for each evaluation sample. The measurements of the total light transmittance (%), image sharpness (%) by the reflection method, and the maximum spectral transmittance (%) were the same as the measurements in <<2-1. Total light transmittance>>, <<2-2. Image sharpness by the reflection method>>, and <<2-3. Spectral transmittance>>, respectively. The measurement results of the total light transmittance (%) are shown in the column of "Tt" in "After S-UV408h" in Table 1. The measurement results of the image sharpness (%) by the reflection method are shown in the column of "DOI" in "After S-UV408h" in Table 1. The measurement results of the maximum spectral transmittance (%) are shown in the column of "Spectral transmittance" in "After S-UV408h" in Table 1.

[0242]

Table 1

[0243] In Comparative Example 1, the paint used for forming the resin layer was a colored paint for forming the topcoat layer of a steel structure assumed to be installed outdoors. In Comparative Example 1, the total light transmittance was low and the transmission haze was high. Also, the image sharpness was large and the lighting device was clearly reflected during the visibility evaluation. As a result, the evaluation regarding the visibility of the base was extremely poor.

[0244] In Comparative Example 2, an acrylic film containing an ultraviolet absorber was used. In the coating sheet of Comparative Example 2, the image sharpness increased. Due to the reflection of the lighting device, it was difficult to observe the base.

[0245] In Comparative Example 3, the visibility of the base was good. However, since the coating sheet of Comparative Example 3 did not contain a weathering agent, it was damaged in the weather resistance test. Since the coating sheet of Comparative Example 4 also did not contain a weathering agent, it disintegrated in the weather resistance test.

Explanation of symbols

[0246] 10: Steel structure, 11: Surface, 12: Deteriorated part, 15: Bonding layer, 18: Rust preventive layer, 19: Topcoat layer, 20: Steel material, 22: Substrate adjustment surface, 30: Coating sheet, 31: First surface, 32: Second surface, 41: Substrate, 42: Weather resistant layer, 43: Bonding layer, 44: Barrier layer, 45: Second bonding layer, 46: Release film, 50: Coating film, 50P: Active film, 51: Rust preventive layer, 52: First undercoat layer, 53: Second undercoat layer, 54: Intermediate coat layer, 55: Topcoat layer, 60: Rust, 100: Steel structure

Claims

1. A coating sheet used for coating steel materials, comprising a first surface and a second surface, wherein the first surface faces away from the steel material, the total light transmittance is 70% or more, the image sharpness with the first surface as the incident surface is 5.0% or less, and the maximum spectral transmittance at a wavelength of 300 nm or more and 350 nm or less is 1.0% or less. The coating sheet.

2. The coating sheet according to claim 1, wherein the transmission haze is 97% or less.

3. including a base material and a weather-resistant layer in this order from the second surface toward the first surface, The coating sheet according to claim 1, wherein the base material contains a polyolefin.

4. including a base material and a weather-resistant layer in this order from the second surface toward the first surface, The coating sheet according to claim 1, wherein the weather-resistant layer contains a cured product of an electron beam curable resin composition.

5. including a barrier layer and a weather-resistant layer in this order from the second surface toward the first surface, The coating sheet according to claim 1, wherein the weather-resistant layer contains an ultraviolet absorber.

6. The water vapor transmission rate in an environment of a temperature of 40 ° C and a humidity of 90% RH is 3.0 g / (m ２ ·day) or less. The coating sheet according to claim 1.

7. After a weather resistance test of 408 hours, the total light transmittance is 70% or more, the image sharpness with the first surface as the incident surface is 7.0% or less, and the maximum spectral transmittance at a wavelength of 300 nm or more and 350 nm or less is 1.0% or less. The coating sheet according to claim 1.

8. The coating sheet according to claim 1, comprising, in order from the second surface toward the first surface, a bonding layer and a base material.

9. The steel material, A steel structure comprising the coating sheet according to any one of claims 1 to 8.

10. A step of performing substrate adjustment on a deteriorated part of a steel structure, A method for correcting a steel structure, comprising a step of coating a steel material that has been substrate-adjusted with the coating sheet according to any one of claims 1 to 8.

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