Method for repairing a steel structure and repaired steel structure

Abstract

[Problem] To provide a method whereby a steel structure having a deteriorated part can be repaired in a short period of time. [Solution] A method for repairing a steel structure that has a deteriorated part, said method including: a first step for preparing an adhesive sheet comprising a support body and an adhesive layer which is provided on one surface of the support body; a second step for subjecting the deteriorated part of the steel structure to surface preparation to form a surface-prepared surface which may have an active film; a third step for subjecting the surface-prepared surface of the steel structure to a rust-proofing treatment to form a rust-proof surface; and a fourth step for disposing the adhesive sheet on the rust-proof surface of the steel structure.

Description

Technical Field

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

Background Art

[0002] Steel structures such as bridges are mainly formed of steel materials. When the steel materials deteriorate, repair of the steel structure becomes necessary. Conventionally, various repair methods have been studied (see, for example, the background art of Patent Document 1). As a method for repairing a steel structure having a deteriorated portion, for example, after performing substrate conditioning such as blasting on the deteriorated portion of the steel structure, applying an anticorrosive primer, applying an epoxy resin paint or the like excellent in blocking property of corrosion factors (water or oxygen), and then applying a fluororesin paint or the like excellent in weather resistance is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Disclosure of the Invention

[0004] However, the above-described method requires a long construction period and a large number of painting steps. An object of the present disclosure is to provide a method capable of repairing a steel structure having a deteriorated portion in a short period of time.

[0005] The method for repairing a steel structure according to the present disclosure is a method for repairing a steel structure having a deteriorated portion, including: a first step of preparing an adhesive sheet including a support and an adhesive layer provided on one surface of the support; a second step of performing substrate conditioning on the deteriorated portion of the steel structure to form a substrate conditioning surface that may have an active film; a third step of performing rust prevention treatment on the substrate conditioning surface of the steel structure to form a rust prevention treatment surface; and a fourth step of disposing the adhesive sheet on the rust prevention treatment surface of the steel structure.

[0006] According to the present disclosure, a method capable of repairing a steel structure having a deteriorated portion in a short period can be provided.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0008] In this specification, when a plurality of upper limit candidates and a plurality of lower limit candidates for a certain parameter are listed, the numerical range of that parameter may be constituted by combining any one upper limit candidate and any one lower limit candidate. As an example, an explanation will be given for the description "Parameter B is preferably A1 or more, more preferably A2 or more, still more preferably A3 or more, and also preferably A4 or less, more preferably A5 or less, still more preferably 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.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail. The present disclosure can be implemented in many different forms and is not construed as being limited to the description of the embodiments illustrated below. For the sake of clarity in the description, the drawings may schematically represent the widths, thicknesses, shapes, etc. of each layer as compared with the embodiments, but this is merely an example and does not limit the interpretation of the present disclosure. In this specification and each figure, elements that are the same as those already described with respect to the previously presented figures may be denoted by the same reference numerals, and detailed descriptions may be omitted as appropriate.

[0010] The method for repairing a steel structure of the present disclosure is a method for repairing a steel structure having a deteriorated portion, comprising a first step of preparing an adhesive sheet including a support and an adhesive layer provided on one surface of the support; a second step of performing substrate conditioning on the deteriorated portion of the steel structure to form a substrate conditioning surface that may have an active film; a third step of performing a rust prevention treatment on the substrate conditioning surface of the steel structure to form a rust prevention treatment surface; and a fourth step of disposing the adhesive sheet on the rust prevention treatment surface of the steel structure.

[0011] In one embodiment, the method for repairing a steel structure of the present disclosure further includes a third a step of forming a coating resin layer on the rust prevention treatment surface (e.g., rust prevention coating film) of the steel structure. In one embodiment, the method for repairing a steel structure of the present disclosure further includes a fifth step of forming a topcoat film on the surface of the adhesive sheet disposed on the rust prevention treatment surface of the steel structure.

[0012] In the first step, an adhesive sheet is prepared. In the first step, a steel structure having a deteriorated portion may be prepared. The steel structure to be repaired is a structure having steel as a substrate. Examples of the steel structure include bridges, bridge piers, towers, steel pipes, chimneys, tanks, plants, pipelines, rolled plates, and roofs. Examples of the steel material include alloy steels such as nickel chromium steel, nickel chromium molybdenum steel, chromium steel, chromium molybdenum steel, and manganese steel, and carbon steel. The steel structure may be, for example, a building structure or a civil engineering structure.

[0013] The steel structure to be repaired has, on its surface, portions where rust such as red rust (e.g., iron oxide (Fe2O3)) has occurred due to corrosion factors such as water and oxygen. Also, generally when manufacturing a steel structure, in order to suppress rusting, an anti-rust paint or a corrosion preventive paint or the like is applied onto the steel material to form a coating film (hereinafter also referred to as the "pre-repair coating film" or the "old coating film"). Such a coating film is partially cracked or swollen due to aging deterioration or construction or repair work performed on the steel structure. In this specification, such rusted portions and portions where cracks and swelling of the coating film have occurred are referred to as deteriorated portions of the steel structure. FIG. 1A shows a schematic cross-sectional view of the deteriorated portion of the steel structure. In FIG. 1A, a pre-repair coating film (old coating film) 20 is provided on the steel material 10, and rust 30 has occurred.

[0014] The steel structure to be repaired has deteriorated portions. In the present disclosure, substrate adjustment is performed on the deteriorated portions to form a substrate adjustment surface that may have an active film, anti-rust treatment is performed on the substrate adjustment surface to form an anti-rust treatment surface, and an adhesive sheet is disposed on the anti-rust treatment surface. In this way, the steel structure having deteriorated portions can be repaired. Such a repair method can perform repair treatment on the steel structure in a short period of time and at low cost as compared with, for example, heavy anti-corrosion coating.

[0015] The adhesive sheet includes a support and an adhesive layer provided on one surface of the support.

[0016] As the support, for example, a resin film is preferable. Examples of the resin material constituting the resin film 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 support may be a single layer or a multilayer, and may be, for example, a laminated film of resin films.

[0017] The support may contain additives. Examples of the additives include pigments, dyes, colorants, antistatic agents, flame retardants, fungicides, ultraviolet absorbers, antioxidants, light stabilizers, plasticizers, leveling agents, flow regulators, defoaming agents, and dispersants. From the viewpoint of suppressing the deterioration of the repaired steel structure and also from the viewpoint of suppressing the deterioration of the adhesive layer and other parts, it is preferable that the support has excellent weather resistance. From such a viewpoint, the support may contain weathering agents such as ultraviolet absorbers, antioxidants, and light stabilizers. Thereby, for example, the topcoat film described later can be made thinner, and the formation of the topcoat film can be omitted.

[0018] Considering the finish after repairing the steel structure, that is, the finish after attaching the adhesive sheet to the steel structure, as well as the handleability and ease of attachment of the adhesive sheet, the thickness of the support is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 30 μm or more, even more preferably 50 μm or more, particularly preferably 100 μm or more, and preferably 5000 μm or less, more preferably 4000 μm or less, still more preferably 3000 μm or less, even more preferably 2000 μm or less, particularly preferably 1000 μm or less.

[0019] The support may include a fiber-reinforced resin layer. An adhesive sheet provided with such a support is, for example, excellent in impact resistance. The fiber-reinforced resin layer is, for example, a layer containing a resin material and reinforcing fibers. Examples of the resin material include the resin materials described above. 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 contain a glass mesh as the reinforcing fibers.

[0020] The thickness of the fiber-reinforced resin layer is preferably 50 μm or more, more preferably 75 μm or more, still more preferably 100 μm or more, even more preferably 125 μm or more, particularly preferably 150 μm or more, and preferably 550 μm or less, more preferably 525 μm or less, still more preferably 500 μm or less, even more preferably 475 μm or less, particularly preferably 450 μm or less. The adhesive sheet provided with the fiber-reinforced resin layer having such a thickness is excellent in, for example, impact resistance.

[0021] The support may include, for example, a laminate including a fiber-reinforced resin layer and a resin layer in this order in the thickness direction, or may include a laminate including a first resin layer, a fiber-reinforced resin layer, and a second resin layer in this order in the thickness direction. Examples of the resin material constituting the resin layer, the first resin layer, and the second resin layer include the resin materials described above. The support may include, for example, a laminate including a fiber-reinforced resin layer containing polyethylene and a glass mesh and a polyethylene layer in this order, or may include a laminate including a first polyethylene layer, a fiber-reinforced resin layer containing polyethylene and a glass mesh, and a second polyethylene layer in this order. The thicknesses of the resin layer, the first resin layer, and the second resin layer are each independently preferably 10 μm or more, more preferably 20 μm or more, still more preferably 30 μm or more, even more preferably 50 μm or more, particularly preferably 100 μm or more, and preferably 1000 μm or less, more preferably 800 μm or less, still more preferably 600 μm or less, even more preferably 500 μm or less, particularly preferably 400 μm or less.

[0022] The support may include, for example, a gas barrier layer such as a vapor deposition film. Such a support includes, for example, a gas barrier film, particularly a vapor deposition film, including a resin film and a gas barrier layer such as a vapor deposition film provided on the resin film. The adhesive sheet provided with such a support is excellent in gas barrier properties, particularly oxygen barrier properties and water vapor barrier properties, and can, for example, suppress rusting of a repaired steel structure and deterioration of a coating film. Examples of the resin film in the gas barrier film include the resin films described above. The thickness of the resin film is preferably 5 μm or more, more preferably 10 μm or more, preferably 100 μm or less, and more preferably 50 μm or less. Examples of the vapor deposition film include a vapor deposition film containing one or more metals, a vapor deposition film containing one or more inorganic oxides, and a vapor deposition film containing one or more metals and one or more inorganic oxides. Examples of the metal 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 carbon oxide (carbon-containing silicon oxide). Among these, an aluminum vapor deposition film, an aluminum oxide (alumina) vapor deposition film, and a silicon oxide (silica) vapor deposition film are preferable. The thickness of the vapor deposition film is preferably 1 nm or more, more preferably 5 nm or more, still more preferably 10 nm or more, preferably 150 nm or less, more preferably 100 nm or less, and still more preferably 80 nm or less. Examples of the method for forming the vapor deposition film include physical vapor deposition methods (Physical Vapor Deposition method, PVD method) such as vacuum vapor deposition method, sputtering method, and ion plating method, and chemical vapor deposition methods (Chemical Vapor Deposition method, CVD method) such as plasma chemical vapor deposition method, thermal chemical vapor deposition method, and photo chemical vapor deposition method. Examples of the vapor deposition film include vapor deposition polyester films such as vapor deposition polyethylene terephthalate film, and vapor deposition polyamide film.

[0023] The support body having a gas barrier layer may include, for example, a laminate including a gas barrier film, a fiber-reinforced resin layer, and a resin layer in this order, or may include a laminate including a gas barrier film, a first resin layer, a fiber-reinforced resin layer, and a second resin layer in this order. From the viewpoint of interlayer adhesiveness, a laminate including a gas barrier film, a first resin layer, a fiber-reinforced resin layer, and a second resin layer in this order is preferable, and it is preferable that the gas barrier film is arranged so that the gas barrier layer faces the first resin layer side.

[0024] The oxygen transmission rate (OTR, unit: cc / (m2·day·atm)) of the adhesive sheet having a gas barrier layer is preferably 3.0 or less, more preferably 2.5 or less, and still more preferably 2.0 or less. The lower limit value of OTR is preferably lower, but may be, for example, 0.01, 0.05, or 0.1. In this specification, OTR is measured in an environment of a temperature of 23°C and a humidity of 60%RH in accordance with JIS K7126-2:2006. The oxygen transmission rate can be measured using an oxygen transmission rate measuring device (manufactured by MOCON, OX-TRAN2 / 20).

[0025] The water vapor transmission rate (WVTR, unit: g / (m2·day)) of the adhesive sheet having a gas barrier layer is preferably 3.0 or less, more preferably 2.5 or less, and still more preferably 2.0 or less. The lower limit value of WVTR is preferably lower, but may be, for example, 0.01, 0.05, or 0.1. In this specification, WVTR is measured in an environment of a temperature of 40°C and a humidity of 90%RH in accordance with JIS K7129-2:2019. WVTR can be measured using a water vapor transmission rate measuring device (manufactured by MOCON, PERMATRAN-w 3 / 33).

[0026] The layer constituting the surface opposite to the surface facing the adhesive layer in the support body is preferably a resin layer such as a polyolefin, an acrylic resin, an acrylic urethane resin, or a urethane resin from the viewpoint of adhesion to the overcoat film described later.

[0027] The support may include a surface resin layer as the surface layer opposite to the surface layer facing the adhesive layer. Thereby, for example, the weather resistance of the repaired steel structure is improved, and rust prevention can be ensured even after a long period has passed since construction. Also, a colored surface resin layer may be formed. In this case, the fifth step described later may be omitted.

[0028] Examples of the resin material constituting the surface resin layer include fluororesin, urethane resin, acrylic resin, butadiene resin, silicone resin, vinyl ester resin, and epoxy resin. Among these, fluororesin is preferred. Examples of the fluororesin include polyvinyl fluoride, polytetrafluoroethylene, perfluoroalkoxy alkane, and ethylene-tetrafluoroethylene copolymer. The surface resin layer may contain additives such as pigments, dyes, dispersants, defoamers, thickeners, leveling agents, anti-settling agents, anti-dripping agents, anti-algal agents, anti-fungal agents, preservatives, ultraviolet absorbers, antioxidants, and light stabilizers.

[0029] The thickness of the surface resin layer is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 15 μm or more, and preferably 200 μm or less, more preferably 150 μm or less, still more preferably 100 μm or less.

[0030] The adhesive layer contains a component having adhesiveness. Examples of the component having adhesiveness include acrylic resin, vinyl chloride-vinyl acetate copolymer, vinyl acetate resin, polyolefin, polyester, polyurethane, silicone resin, and rubber-based resin. In this specification, "adhesion" means adhesion in a broad sense, and the concept of "adhesion" includes adhesion.

[0031] In one embodiment, the subsequent layer is a pressure-sensitive adhesive layer, i.e., an adhesive layer. The adhesive layer is a layer formed by an adhesive (pressure-sensitive adhesive) and exhibits an adhesive feeling as a tackiness at room temperature (e.g., 23°C). Examples of the adhesive include acrylic adhesives, urethane adhesives, silicone adhesives, and rubber adhesives. Among these, acrylic adhesives are preferred from the viewpoints of a long-term protection function being required, adhesion to an adherend surface (e.g., a rust-preventive coating film) having a large step with the adhesive layer, and adhesion between the adhesive layer and the support.

[0032] The adhesive layer may contain additives. Examples of the additives include pigments, dyes, colorants, antistatic agents, flame retardants, fungicides, ultraviolet absorbers, antioxidants, light stabilizers, crosslinking agents, tackifiers, plasticizers, leveling agents, flow regulators, defoamers, and dispersants.

[0033] The storage elastic modulus (G’) at 40°C of the adhesive layer, preferably the adhesive layer, that comes into contact with the adherend when the adhesive sheet is attached to the adherend is preferably 0.05 MPa or more and 1 MPa or less. For example, it may be 0.1 MPa or more and may be 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 tend to 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 tend to be suppressed.

[0034] The storage elastic modulus is measured by the following method. Two test pieces 90 are produced from the adhesive sheet according to the method for producing test pieces described in 6.2 of JIS K7244-1:1998. Since the test pieces 90 are produced from the adhesive sheet, the test pieces 90 have a support 91 corresponding to the support of the adhesive sheet and an adhesive layer 92 corresponding to the adhesive layer of the adhesive sheet.

[0035] Subsequently, the two produced test pieces 90 are attached to a measuring device 70 as shown in Fig. 2A. As shown in Fig. 2A, the measuring device 70 has a plate 71 and a jig 72. The jig 72 has 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 pieces 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 pieces 90 in the direction perpendicular to the plane of Fig. 2A. 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. 2A, 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.

[0036] 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. 2A and the thicknesses w3 and w4 of each of the pair of plate-like portions 73 can be specified. The thicknesses w2, w3, and w4 can be specified by measuring with a caliper. Further, after fixing two test pieces 90 to the jig 72 as shown in FIG. 2A, the dimensions of the jig 72 with the two test pieces 90 sandwiched therebetween are specified. As the dimensions of the jig 72 with the two test pieces 90 sandwiched therebetween, 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. 2A 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 with the two test pieces 90 sandwiched therebetween. The thickness w1 of the test piece 90 can be calculated by subtracting the thicknesses w2, w3, and w4 from the distance w5 and dividing the result by 2. The specified thickness w1 of the test piece 90 is used for the measurement of the storage elastic modulus (G').

[0037] After fixing two test pieces 90 to the jig 72 as shown in FIG. 2A, 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.

[0038] The measurement of the storage elastic modulus (G') is performed under the following conditions. · Atmosphere gas: Nitrogen · Attachment mode: Solid shear mode · Temperature dependence measurement (heating at a temperature program and measuring the elastic modulus when applying 10 Hz at each temperature) · 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: Adjust to 0 g when fixing two test pieces 90 to the jig 72. · Strain: The value automatically set when inputting the sample length 0.05 Automatic adjustment mode

[0039] The measurement of the storage elastic modulus (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.

[0040] The thickness of the adhesive layer is preferably 10 μm or more, more preferably 20 μm or more, still more preferably 30 μm or more, even more preferably 40 μm or more, particularly preferably 50 μm or more, and preferably 1000 μm or less, more preferably 500 μm or less, still more preferably 300 μm or less, even more preferably 250 μm or less, still more preferably 200 μm or less, even more preferably 180 μm or less, particularly preferably 150 μm or less. The same applies to the thicknesses of the first adhesive layer such as the first adhesive layer and the second adhesive layer such as the second adhesive layer described later.

[0041] The adhesive sheet may, for example, be provided with a coloring material layer on the surface opposite to the surface on which the adhesive layer is provided on the support. By using an adhesive sheet provided with a coloring material layer, for example, a repaired portion having a beautiful finish can be easily formed. The coloring material layer may exhibit the same color or a similar color as the object to be repaired.

[0042] The adhesive sheet may, for example, be provided with a composite adhesive layer including a first adhesive layer, a base material layer, and a second adhesive layer in this order in the thickness direction, and preferably, a composite adhesive layer including a first adhesive layer, a base material layer, and a second adhesive layer in this order in the thickness direction. Such an adhesive sheet tends to be excellent in followability to the step and impact resistance when the surface of the adherend has a step. For example, the substrate adjustment surface of a steel structure after three kinds of pickling usually has an active film, so the rust prevention treatment surface also has large irregularities. Such an adhesive sheet is excellent in step followability to the rust prevention treatment surface of a steel structure and can adhere well to the rust prevention treatment surface.

[0043] Examples of the material constituting the base material layer include acrylic resins, urethane resins, polyolefins, and rubbers including acrylic rubbers and other elastomers, and in one embodiment, it is an acrylic resin. The base material layer may contain the above additives.

[0044] The base material layer 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 semi-independent bubble structure in which a closed-cell structure and an open-cell structure are mixed. Examples of the base material layer having a bubble structure include a foam layer, specifically, an acrylic resin foam (acrylic foam), a urethane resin foam (urethane foam), a polyolefin foam, and a rubber foam including acrylic rubber and other elastomers, and in one embodiment, it is an acrylic resin foam.

[0045] From the viewpoints of step-following property and impact resistance, the thickness of the base material layer is preferably 300 μm or more, more preferably 400 μm or more, still more preferably 500 μm or more, particularly preferably 600 μm or more, and preferably 2000 μm or less, more preferably 1800 μm or less, still more preferably 1500 μm or less, particularly preferably 1200 μm or less.

[0046] The thickness of the composite adhesive layer including the first adhesive layer, the base material layer, and the second adhesive layer, preferably the thickness of the composite adhesive layer including the first adhesive layer, the base material layer, and the second adhesive layer, is preferably 350 μm or more, more preferably 450 μm or more, still more preferably 550 μm or more, particularly preferably 650 μm or more, and preferably 2050 μm or less, more preferably 1850 μm or less, still more preferably 1550 μm or less, particularly preferably 1250 μm or less. When the thickness of the composite adhesive layer is equal to or greater than the lower limit value, for example, even when there are large irregularities on the adherend surface, the adhesive sheet can adhere well to the adherend surface.

[0047] When using an adhesive sheet having a composite adhesive layer, for example, even if the 3a process (e.g., unevenness adjustment process) described later is not provided, the adhesive sheet can sufficiently follow the unevenness of the rust-preventive treatment surface, and the adhesiveness tends to be ensured well.

[0048] Specific examples of the adhesive sheet include an adhesive sheet including a resin layer, a fiber-reinforced resin layer, a first adhesive layer, a base material layer, and a second adhesive layer in this order; an adhesive sheet including a second resin layer, a fiber-reinforced resin layer, a first resin layer, a first adhesive layer, a base material layer, and a second adhesive layer in this order; an adhesive sheet including a resin layer, a fiber-reinforced resin layer, a gas barrier film, a first adhesive layer, a base material layer, and a second adhesive layer in this order; and an adhesive sheet including a second resin layer, a fiber-reinforced resin layer, a first resin layer, a gas barrier film, a first adhesive layer, a base material layer, and a second adhesive layer in this order. In these examples, each resin layer is, for example, a polyethylene layer, the fiber-reinforced resin layer is, for example, a polyethylene layer containing a glass mesh, and the base material layer is, for example, an acrylic resin layer.

[0049] Specific examples of the adhesive sheet include an adhesive sheet including a resin layer, a fiber-reinforced resin layer, a first adhesive layer, a base material layer, and a second adhesive layer in this order; an adhesive sheet including a second resin layer, a fiber-reinforced resin layer, a first resin layer, a first adhesive layer, a base material layer, and a second adhesive layer in this order; an adhesive sheet including a resin layer, a fiber-reinforced resin layer, a gas barrier film, a first adhesive layer, a base material layer, and a second adhesive layer in this order; and an adhesive sheet including a second resin layer, a fiber-reinforced resin layer, a first resin layer, a gas barrier film, a first adhesive layer, a base material layer, and a second adhesive layer in this order. In these examples, each resin layer is, for example, a polyethylene layer, the fiber-reinforced resin layer is, for example, a polyethylene layer containing a glass mesh, each adhesive layer is, for example, an acrylic adhesive layer, and the base material layer is, for example, an acrylic resin layer.

[0050] Subsequently, the adhesive sheet may be provided with a release film on the adhesive layer. Thereby, the adhesive layer can be protected from dust and the like. Before using the adhesive sheet, the release film is peeled off from the adhesive layer. Thereby, the adhesive layer is exposed, and the adhesive sheet becomes in a state where it can be pasted. Examples of the release film 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.

[0051] Since the adhesive sheet has an adhesive layer, for example, it is possible to paste the adhesive sheet manually by an operator. Of course, it is also possible to paste the adhesive sheet using a machine. Before pasting the adhesive sheet, the adhesive sheet may be cut to an appropriate size according to the shape and size of the deteriorated part of the steel structure.

[0052] In the second step, substrate conditioning (substrate treatment) is performed on the deteriorated part of the steel structure to form a substrate conditioning surface that may have an active film. Examples of the method for conditioning the substrate of the steel structure include keren treatment. In keren treatment, generally, blast treatment, power tools or hand tools are used to remove old paint films, rust, dust, dirt, etc. Keren treatment has grades of 1-type keren, 2-type keren, 3-type keren, and 4-type keren. The smaller the grade number, the higher the level of substrate conditioning.

[0053] "1-type keren" is substrate conditioning that removes all rust and old paint films to expose the steel surface, and substrate conditioning is mainly performed by blast treatment. "2-type keren" is substrate conditioning that removes rust and old paint films to expose the steel surface, and substrate conditioning is mainly performed by power tools and / or hand tools. "Three - type scarification" means substrate conditioning that leaves the live film (sound coating film) among the old coating films while removing other defective parts (rust, and dead films (coating films with cracks and bulges) among the old coating films). Substrate conditioning is mainly performed with power tools and / or hand tools. In three - type scarification, there are advantages such as fewer working areas and lower working costs compared to one - type scarification and two - type scarification. However, since the live film of the old coating film remains, the substrate - conditioned surface after three - type scarification tends to have large irregularities. Rusty surfaces may remain on the substrate - conditioned surface after three - type scarification. The height of the irregularities is, for example, 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. Fig. 1B shows a schematic cross - sectional view of the case where substrate conditioning is performed on the deteriorated part of a steel structure by three - type scarification. In Fig. 1B, the old coating film 20 has been removed except for the live film 22, and the rust 30 has also been removed. "Four - type scarification" means substrate conditioning that removes powdery substances (including loose rust) and dirt etc. adhering to the surface, and substrate conditioning is mainly performed with hand tools and / or brushes.

[0054] Examples of power tools include a disk sander and a wire wheel. Examples of hand tools include a wire brush, a scraper, a scarification bar, and sandpaper.

[0055] In the present disclosure, it is preferably to perform at least substrate conditioning of three - type scarification. The substrate - conditioned surface after three - type scarification may have a live film and a rusty surface. In the present disclosure, it is also possible to perform substrate conditioning of one - type scarification or two - type scarification. However, from the viewpoints of securing the working space, construction period, cost, etc., one - type scarification and two - type scarification tend to be costly. According to the repair method of the present disclosure, there is no need to perform one - type scarification and two - type scarification that are costly, and the steel structure can be repaired by three - type scarification with low cost.

[0056] In the third step, rust prevention treatment is performed on the surface of the steel structure for substrate adjustment to form a rust prevention treatment surface. Examples of methods for performing rust prevention treatment on the surface of the steel structure for substrate adjustment include, for example, a method of forming a rust prevention coating film by applying a rust inhibitor or a rust prevention paint. Examples of coating methods include, for example, brush coating, roller coating, and spray coating (for example, air spray, airless spray). Fig. 1C shows a schematic cross-sectional view when rust prevention treatment is performed on the surface of the steel structure for substrate adjustment to form a rust prevention coating film. In Fig. 1C, a rust prevention coating film 40 is formed on the steel material 10 and the live film 22.

[0057] In the repair method of the present disclosure, rust prevention treatment and the pasting of the adhesive sheet are performed separately. By providing the adhesive layer of the adhesive sheet with a rust prevention function and not performing rust prevention treatment before pasting the adhesive sheet on the surface of the steel structure for substrate adjustment, the repair method of the present disclosure can more clearly obtain the effect of the rust prevention treatment itself. In addition, the rust prevention coating film formed by the rust prevention treatment can fill the unevenness of the substrate adjustment surface having unevenness to a certain extent, and can improve the adhesion of the adhesive sheet. In addition, the method of the present disclosure for pasting the adhesive sheet can perform repair in a short period compared with a method of performing multiple painting and drying treatments at the construction site, and is excellent from the viewpoints of work simplicity, repair treatment cost, and quality control of the steel structure after repair.

[0058] The thickness (dry film thickness) of the rust prevention coating film formed by the rust prevention treatment is preferably 10 μm or more, more preferably 30 μm or more, still more preferably 50 μm or more, even more preferably 100 μm or more, particularly preferably 150 μm or more, and preferably 1000 μm or less, more preferably 800 μm or less, still more preferably 600 μm or less, particularly preferably 500 μm or less. If the thickness is equal to or greater than the lower limit value, a sufficient rust prevention effect tends to be obtained, and if the thickness is equal to or less than the upper limit value, workability and economy tend to be excellent.

[0059] Examples of the rust inhibitor include inorganic rust inhibitors and organic rust inhibitors. Examples of inorganic rust inhibitors include inorganic acids and their salts, specifically, red lead, lead monoxide, basic lead chromate, dithioamide lead, calcium plumbate, basic lead sulfate, zinc chromate, zinc powder, valve stem, nitrite, sulfite, silicate, metasilicate, phosphate, polyphosphate, hypophosphite, phosphite, molybdate, phosphomolybdate, borate, metaborate, tungstate, carbonate and chromate. Also included are phosphate compounds, vanadium compounds, niobium compounds, zirconium compounds and zinc oxide. Examples of salts in these cases include ammonium salts, calcium salts, magnesium salts, aluminum salts, zinc salts, manganese salts and barium salts.

[0060] Examples of organic rust inhibitors include organic amine compounds, organic amine salts, tannic acid, carboxylic acids and esters or salts of these acids, sulfonates, organic phosphates, benzotriazole compounds, benzothiazole compounds, mercaptan compounds, guanidino group-containing compounds, biguanidino group-containing compounds, thiocarbonyl group-containing compounds, alkylphenol compounds, diisopropylammonium nitrite and dicyclohexylammonium nitrite.

[0061] Examples of rust preventive paints include epoxy resin paints, urethane resin paints, acrylic resin paints, silicon acrylic resin paints, styrene resin paints, fluororesin paints, and zinc-rich paints containing an organic binder and zinc powder. In one embodiment, the rust preventive paint contains a binder and, optionally, the above-described rust inhibitor. Examples of binders in the rust preventive paint include organic binders such as epoxy resin, urethane resin, acrylic resin, silicon acrylic resin, styrene resin and fluororesin; and inorganic binders such as alkyl silicate.

[0062] Examples of rust inhibitors and rust preventive paints include, from the classification of rust prevention mechanisms, for example, rust conversion type and salt / iron ion detoxification type, and either can be used.

[0063] As a rust preventive and a rust preventive paint, in the classification of rust prevention mechanisms, a rust preventive and a rust preventive paint of a type that prevents rust by stabilizing iron ions with a two-component curable ion trap agent may be used.

[0064] When a rust conversion type rust preventive and rust preventive paint exerts its rust preventive effect on steel materials, black rust is generated. As a result, the rust conversion type rust preventive and rust preventive paint is colored when exerting its rust preventive effect. On the other hand, a salt / iron ion detoxification type and a type of rust preventive and rust preventive paint by stabilizing iron ions with a two-component curable ion trap agent are not colored when exerting their rust preventive effects on steel materials. For this reason, when a rust preventive film is formed on the surface of a steel material by using a salt / iron ion detoxification type or a type of rust preventive or rust preventive paint by stabilizing iron ions with a two-component curable ion trap agent, it is easier to visually recognize the steel material through the rust preventive film. In particular, as shown in Fig. 1D, when the adhesive sheet and the rust preventive film cover the steel material, it is easier to visually recognize the steel material through the adhesive sheet and the rust preventive film. For this reason, an inspector can inspect the steel material without peeling off the adhesive sheet or removing the rust preventive film. In particular, it is easier to inspect whether cracks or the like have occurred on the surface of the steel material.

[0065] The rust preventive paint may be a one-component curable rust preventive paint or a two-component curable rust preventive paint composed of a main agent and a curing agent. In the case of a two-component curable rust preventive paint, generally, a main agent containing a binder and, if desired, a rust preventive agent and a curing agent for promoting a crosslinking reaction are stored in separate containers and mixed just before use. For example, from the viewpoints of high adhesion to the substrate adjustment surface, high coating film strength, and the ability to form a dense rust preventive film, and also from the viewpoint of adhesion to the adhesive sheet, a two-component curable rust preventive paint is preferred, a two-component curable epoxy resin paint and a two-component curable urethane resin paint are more preferred, and a two-component curable epoxy resin paint is even more preferred.

[0066] In one embodiment, the two-component curable epoxy resin paint contains 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. As for urethane resin paints, there are two-component curable types composed of a polyol-based compound and an isocyanate-based compound, and one-component curable types that cure by moisture in the air, etc. Two-component curable urethane resin paints are preferred.

[0067] The rust preventive paint may contain a moisture-curable resin. The moisture-curable resin has an isocyanate group as a reactive group. The isocyanate group of the moisture-curable resin reacts with water and cures by the reaction shown in the following formula (I). That is, first, carbamic acid is generated by the reaction of the isocyanate group of the moisture-curable resin with water. Subsequently, amine is generated by the decomposition of carbamic acid. Subsequently, a crosslinking reaction occurs in which the amine reacts with the isocyanate group of the moisture-curable resin to form a urea bond. By this crosslinking reaction, the moisture-curable resin is cured. By the rust preventive paint containing a moisture-curable resin, a rust preventive effect is obtained by removing water that can be a corrosion factor.

Chemical formula

[0068] As an example, the moisture-curable resin contained in the rust preventive paint is a urethane resin. In this case, the rust preventive paint can be a two-component curable urethane resin paint of the type that is harmless to salts and iron ions.

[0069] When the rust preventive paint contains a moisture-curing resin, as shown in the above formula (I), carbon dioxide gas may be generated by the reaction of the moisture-curing resin with water. When the adhesive sheet and the rust preventive coating film cover the steel material as shown in Fig. 1D, from the viewpoint of suppressing the generated carbon dioxide gas from remaining in the adhesive sheet as bubbles without passing through the adhesive sheet, it is preferable that the adhesive sheet is not provided with an oxygen barrier property. By not providing the adhesive sheet with an oxygen barrier property, the carbon dioxide gas can easily pass through the adhesive sheet, and the remaining of the carbon dioxide gas as bubbles in the adhesive sheet can be suppressed. As a result, the visual recognition of the rust preventive coating film and the steel material through the adhesive sheet is less likely to be hindered by the bubbles. From the above, when a rust preventive paint containing a moisture-curing resin is used, from the viewpoint of enabling visual recognition of the rust preventive coating film and the steel material through the adhesive sheet, it is preferable that the adhesive sheet is not provided with an oxygen barrier property. Further, when a rust preventive paint containing a moisture-curing resin and not colored is used, from the viewpoint of enabling visual recognition of the steel material through the adhesive sheet and the rust preventive coating film, it is preferable that the adhesive sheet is not provided with an oxygen barrier property.

[0070] On the other hand, particularly when a rust preventive paint that does not contain a moisture-curing resin is used, it is preferable that the adhesive sheet has oxygen barrier properties from the viewpoint of making it difficult for oxygen, which can be a corrosion factor, to reach the rust preventive coating film and the steel material. Particularly when a rust preventive paint that does not contain a moisture-curing resin is used, even if the adhesive sheet is provided with oxygen barrier properties, it is possible to prevent bubbles from forming in the adhesive sheet. For this reason, when a rust preventive paint that does not contain a moisture-curing resin and is not colored is used, by imparting oxygen barrier properties to the adhesive sheet, it is possible to make it difficult for oxygen to reach the rust preventive coating film and the steel material, and at the same time, the rust preventive coating film and the steel material can be visually recognized through the adhesive sheet. Particularly when a rust preventive paint that does not contain a moisture-curing resin and is not colored is used, by imparting oxygen barrier properties to the adhesive sheet, it is possible to make it difficult for oxygen to reach the rust preventive coating film and the steel material, and at the same time, the steel material can be visually recognized through the adhesive sheet and the rust preventive coating film. The rust preventive paint that does not contain a moisture-curing resin and is not colored can be, for example, a type of rust preventive paint that prevents rust by stabilizing iron ions with the two-component curing type ion trap agent described above.

[0071] As an example, the oxygen transmission rate (OTR) of the adhesive sheet provided with oxygen barrier properties is 6.57 cc / (m2·day·atm) or less.

[0072] Regardless of whether the rust preventive paint contains a moisture-curing resin or not, the adhesive sheet may be provided with water vapor barrier properties. This makes it difficult for water, which can be a corrosion factor, to reach the rust preventive coating film and the steel material. As an example, the water vapor transmission rate (WVTR) of the adhesive sheet provided with water vapor barrier properties is 3.0 g / (m2·day) or less.

[0073] From the viewpoint of making it possible to visually recognize the rust preventive coating film and the steel material through the adhesive sheet as described above, the adhesive sheet is preferably not colored and more preferably transparent as described later.

[0074] The rust preventive paint may contain additives such as rosins, plasticizers, extender pigments, coloring pigments, solvents, curing accelerators, coupling agents, corrosive ion fixatives, anti-sagging agents, and anti-settling agents, if desired. 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 fixative include hydrotalcite and hydrocalumite.

[0075] The rust preventive coating film provided on the surface conditioning surface of the steel structure preferably has a specular glossiness of 85 degrees or more. The specular glossiness of the rust preventive coating film is preferably 5 or more, more preferably 10 or more, still more preferably 15 or more, even more preferably 20 or more, and particularly preferably 23 or more. Since such a rust preventive coating film has a high specular glossiness, it can be said that it is a dense film, and therefore, the adhesion of the adhesive sheet to the rust preventive coating film tends to be high. The upper limit value of the specular glossiness at 85 degrees is not particularly limited, and for example, it may be 60, may be 50, or may be 40.

[0076] The adhesion of the rust preventive coating film to the surface conditioning surface of the steel structure is preferably high. The rust preventive coating provided on the surface preparation surface of the steel structure preferably has a retention rate of 85-degree specular gloss of 50% or more. Here, the retention rate of 85-degree specular gloss refers to the retention rate of the 85-degree specular gloss of the rust preventive coating surface, which is the surface of the rust preventive coating, before and after performing the 90-degree tape peeling test. Specifically, when the 85-degree specular gloss of the rust preventive coating surface before performing the 90-degree tape peeling test on the rust preventive coating surface is denoted as "Gsb", and the 85-degree specular gloss of the rust preventive coating surface after performing the 90-degree tape peeling test on the rust preventive coating surface is denoted as "Gsa", the above retention rate is represented by Gsa×100 / Gsb. The retention rate of the 85-degree specular gloss of the rust preventive coating is more preferably 60% or more, still more preferably 70% or more, even more preferably 80% or more, particularly preferably 90% or more, and especially preferably 95% or more. The rust preventive coating with a high above retention rate means that it is difficult to peel off from the surface preparation surface in the 90-degree tape peeling test. Therefore, such a rust preventive coating has excellent adhesion to the surface preparation surface of the steel structure.

[0077] <90-degree tape peeling test> From a roll of 24 mm wide cellophane adhesive tape conforming to JIS Z1522:2009, unwind 25 cm in an environment of temperature 23°C and humidity 50%RH, and with the adhesive surfaces of 10 cm bonded together to form a handle, adhere 5 cm of the adhesive surface to the rust preventive coating surface of the steel structure with a 2 kg pressure roller reciprocated twice, and then adhere again by finger pressure so that no air intervenes. Next, manually perform a single strong peeling of the cellophane adhesive tape at a speed of 5 cm / s in a direction 90 degrees 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 strength equivalent to that of this product is used. <85-degree specular gloss> The 85-degree specular gloss of the rust preventive coating surface is measured under the conditions of an incident angle of 85 degrees and an observation angle of 85 degrees in accordance with Method 1 of JIS Z8741-1997. Using a gloss meter, measure the 85-degree specular gloss three times and calculate the average value.

[0078] In the 3a process, a coating resin layer is formed on the rust-preventive treatment surface (e.g., rust-preventive coating film) of the steel structure. Examples of the resin material constituting the coating resin layer include fluororesin, acrylic resin, silicone resin, urethane resin, urea resin, and epoxy resin. The coating resin layer can be formed, for example, using paint. The paint may be a one-component curing type paint or a two-component curing type paint.

[0079] The coating resin layer may contain additives such as pigments, dyes, dispersants, defoamers, thickeners, leveling agents, anti-settling agents, anti-dripping agents, algicides, fungicides, antiseptics, ultraviolet absorbers, antioxidants, and light stabilizers. The paint for forming the coating resin layer may contain an organic solvent and / or water for the purpose of adjusting the viscosity. Examples of the organic solvent include aromatic hydrocarbons, aliphatic hydrocarbons, ketones, acetic esters, ethers, alcohol-based solvents, and mineral spirits.

[0080] The coating resin layer smooths, for example, the steps on the rust-preventive treatment surface of the steel structure. In one embodiment, the 3a process is a so-called unevenness adjustment process. The unevenness adjustment process means a process of filling the unevenness of the base with a paste-like unevenness adjuster to make it smooth. For example, since the base adjustment surface of the steel structure after 3 kinds of degreasing has an active film, it has unevenness on the surface. Even after the rust-preventive treatment, the unevenness tends to exist. When the adhesive sheet is attached to the rust-preventive treatment surface with unevenness in the 4th process described later, corrosion and peeling may progress due to the corrosion factors (water or oxygen) existing in the space between the rust-preventive treatment surface and the adhesive sheet. When the unevenness of the base is filled with an unevenness adjuster to make it smooth, the adhesive sheet can be attached to the steel structure with adjusted unevenness without gaps. Therefore, the entry of corrosion factors (water or oxygen) can be reduced in the repaired steel structure.

[0081] The thickness of the coating resin layer is preferably 100 μm or more, more preferably 200 μm or more, still more preferably 300 μm or more, and preferably 5000 μm or less, more preferably 3000 μm or less, still more preferably 1000 μm or less.

[0082] The coating resin layer can be formed, for example, by a normal coating method. Examples of the coating method include brush coating, roller coating, and spray coating (e.g., air spray, airless spray). For example, a paint is applied to the rust-preventive treated surface of the steel structure (e.g., rust-preventive coating film surface), and natural drying or drying treatment is performed to form the coating resin layer.

[0083] In the fourth step, an adhesive sheet is placed on the rust-preventive treated surface of the steel structure. For example, when the rust-preventive treated surface of the steel structure or a coating resin layer is formed on the rust-preventive treated surface, the adhesive sheet is attached to the rust-preventive treated surface or the coating resin layer surface. Fig. 1D shows a schematic cross-sectional view when the adhesive sheet is placed on the rust-preventive coating film of the steel structure. In Fig. 1D, the adhesive sheet 50 includes a support 52 and an adhesive layer 54 provided on the support 52. The adhesive sheet 50 is arranged such that its adhesive layer 54 is in contact with the rust-preventive coating film 40.

[0084] For example, the adhesive sheet is attached to the steel structure while being pressed at room temperature so that the adhesive layer of the adhesive sheet is at least in contact with the rust-preventive treated surface or the coating resin layer surface of the steel structure. For example, a roller or the like is used to press the adhesive sheet from above. Thereby, the adhesive layer of the adhesive sheet and the rust-preventive treated surface or the coating resin layer surface of the steel structure can be brought into close contact.

[0085] When the adhesive sheet includes a release film, the release film is peeled off from the adhesive layer. Thereby, the adhesive layer is exposed, and the adhesive sheet is in a state where it can be attached. Also, the adhesive sheet may be attached so as to cover, for example, the rust-preventive treated surface and the periphery of the rust-preventive treated surface. The adhesive sheet may be bent up to the end face of the steel structure and attached.

[0086] According to the repair method of the present disclosure described above, for example, compared with heavy anti-corrosion coating, the repair treatment for steel structures can be carried out in a short period of time. Further, in the present disclosure, a large number of coating steps are not particularly necessary, and an adhesive sheet may be used. Therefore, low-cost repair treatment is also possible. Further, since the adhesive sheet is a factory-produced product, pinholes are less likely to occur compared with heavy anti-corrosion coating. For this reason, the adhesive sheet can enhance the repair effect of the steel structure more than the heavy anti-corrosion coating.

[0087] In the fifth step, for example, a topcoat paint (paint composition) is applied to the surface of the adhesive sheet disposed on the rust preventive treatment surface of the steel structure to form a topcoat film. Thereby, for example, the weather resistance of the repaired steel structure is improved, and rust prevention can be ensured even after a long period has elapsed since construction. Further, a colored topcoat film may be formed.

[0088] Examples of the resin material constituting the topcoat film include fluororesin, urethane resin, acrylic resin, butadiene resin, silicone resin, vinyl ester resin, and epoxy resin. Among these, fluororesin is preferable. Examples of the fluororesin include polyvinyl fluoride, polytetrafluoroethylene, perfluoroalkoxy alkane, and ethylene-tetrafluoroethylene copolymer. The topcoat film can be formed, for example, using a topcoat paint. The topcoat paint may be a one-component paint or a two-component paint.

[0089] The topcoat film may contain additives such as pigments, dyes, dispersants, defoamers, thickeners, leveling agents, anti-settling agents, anti-dripping agents, algicides, fungicides, preservatives, ultraviolet absorbers, antioxidants, and light stabilizers. The topcoat paint may contain an organic solvent and / or water for the purpose of adjusting the viscosity. Examples of the organic solvent include aromatic hydrocarbons, aliphatic hydrocarbons, ketones, acetic esters, ethers, alcohol-based solvents, and mineral spirits.

[0090] The thickness of the topcoat film is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 15 μm or more, and preferably 200 μm or less, more preferably 150 μm or less, still more preferably 100 μm or less.

[0091] The topcoat film can be formed, for example, by a normal painting method. Examples of the painting method include brush painting, roller painting, and spray painting (e.g., air spray, airless spray). For example, the topcoat paint is applied to the surface of the adhesive sheet, and natural drying or a drying treatment is performed to form the topcoat film.

[0092] In the present disclosure, by applying the repair method of the steel structure of the present disclosure described above to a steel structure having a deteriorated portion, a repaired steel structure can be manufactured. The details are as described above, and the description here is omitted.

[0093] In one embodiment, the repaired steel structure in the present disclosure includes a steel structure having a substrate adjustment surface that may have an active film, a rust preventive coating film provided on the substrate adjustment surface, and an adhesive sheet disposed on the rust preventive coating film. The repaired steel structure may further include a coating resin layer between the rust preventive coating film and the adhesive sheet. The repaired steel structure may further include a topcoat film on the surface of the adhesive sheet. The details of each element are as described above, and the description here is omitted.

[0094] When the adhesive sheet disposed on the rust preventive coating film in the repaired steel structure is subjected to a 180-degree peel test at a speed of 300 mm / min in accordance with JIS Z0237:2022, it is preferable that cohesive failure occurs in the adhesive sheet, for example, cohesive failure occurs in the adhesive layer or the substrate layer described above. In such a case, it can be said that, for example, the substrate adjustment surface and the rust preventive coating film, and the rust preventive coating film and the adhesive sheet are in good adhesion.

[0095] Regarding the adhesive sheet, an example in which the layer provided in the adhesive sheet is colored has been described above. For example, an example in which the surface resin layer of the support is colored has been described above. In addition, an example in which the adhesive sheet includes a coloring material layer has also been described above. However, the form of the adhesive sheet is not limited to this. The layer provided in the adhesive sheet may not be colored. All the layers provided in the adhesive sheet may not be colored and may be transparent. As a result, the adhesive sheet may be transparent as a whole.

[0096] The materials and members referred to as transparent in this specification may have a total light transmittance of 70% or more. For example, the transmittance of the adhesive sheet as a whole may be 70% or more. The total light transmittance is measured in accordance with JIS K7361-1:1997. When the transmittance of the adhesive sheet is 70% or more, as shown in FIG. 1D, when the adhesive sheet covers the steel material and the rust preventive coating film, the steel material and the rust preventive coating film can be visually recognized through the adhesive sheet. Therefore, a person inspecting the steel material or the rust preventive coating film can inspect the steel material or the rust preventive coating film without peeling off the adhesive sheet. As a result, it is possible to easily repeatedly inspect the steel material and the rust preventive coating film over a long period of time. Furthermore, it is possible to facilitate the inspection of the steel material and the rust preventive coating film from various angles.

[0097] When the adhesive sheet is transparent, the haze of the adhesive sheet is, for example, 97% or less. The haze is measured in accordance with JIS K7136:2000. When the haze of the adhesive sheet is 97% or less, as shown in FIG. 1D, when the adhesive sheet covers the steel material and the rust preventive coating film, it is possible to more easily visually recognize the steel material and the rust preventive coating film through the adhesive sheet.

[0098] Next, the surface of the adhesive sheet that faces the steel structure when the adhesive sheet is placed on the steel structure is referred to as the second surface of the adhesive sheet. In the present embodiment, the second surface is the surface that faces the steel structure when placed on the rust preventive treatment surface of the steel structure. The surface of the adhesive sheet opposite to the second surface is referred to as the first surface of the adhesive sheet. When the adhesive sheet is transparent, the image sharpness (%) by the reflection method on the first surface of the adhesive sheet is, for example, 20% or less when the brush width is 1.0 mm. The image sharpness (%) by the reflection method on the first surface of the adhesive sheet according to the above measurement method may be 7% or less. By setting the upper limit of the above image sharpness (%) as described above, particularly when the image sharpness (%) is 7% or less, the reflection of external objects on the surface of the adhesive sheet is suppressed. As a result, as shown in FIG. 1D, when the adhesive sheet covers the steel material and the rust preventive coating film, it is possible to more easily visually recognize the steel material and the rust preventive coating film through the adhesive sheet.

[0099] Image sharpness is also called DOI or mapping property. Image sharpness is measured in accordance with JIS K7374:2007 except where otherwise specified. The incident surface during measurement is the first surface of the coating sheet. The incident angle of the light incident on the incident surface during measurement is 60°. 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. For the measurement of the image sharpness (%) by the reflection method on the first surface of the adhesive sheet, an image sharpness measuring instrument ICM-1T manufactured by Suga Test Instruments Co., Ltd. can be used.

[0100] When measuring the image sharpness, the sample to be measured is placed on a black mount. The image sharpness is measured in a state where the back surface (second surface) facing the incident surface (first surface) of the sample to be measured is in contact with the black mount.

[0101] 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.

[0102] The image clarity shall be the arithmetic mean value of five measurement values. The five measurement values shall be the measurement values measured at five measurement positions on the adhesive sheet to be evaluated. The five measurement positions shall be located at least 10 mm apart from each other.

[0103] For example, when the adhesive sheet includes an adhesive layer and a base material layer, the adhesive layer and the base material layer may not be colored and may be transparent. Thereby, the adhesive sheet can be made transparent.

[0104] When the adhesive sheet includes an adhesive layer, a base material layer, and a surface resin layer, the adhesive layer, the base material layer, and the surface resin layer may not be colored and may be transparent. Thereby, the adhesive sheet can be made transparent. In this case, the surface resin layer may contain an ultraviolet absorber. Thereby, while making the adhesive sheet transparent, the rust preventive coating film and the portion covered by the surface resin layer of the adhesive sheet can be protected from ultraviolet rays by the surface resin layer.

[0105] When the adhesive sheet is transparent, as described above, a topcoat film may be provided on the surface of the adhesive sheet 50. In this case, while making the adhesive sheet transparent, the rust preventive coating film 40 and the adhesive sheet 50 can be protected from ultraviolet rays by the topcoat film.

[0106] In the following example, the adhesion of the rust preventive coating film was confirmed. A steel plate having a rusted portion (red rust) was prepared. Three types of degreasing were performed on the steel plate. The steel plate after the three types of degreasing had a substrate adjustment surface including an active film of the old coating film (thickness of about 150 μm) and a rusted surface. Rust preventive treatments were performed on the substrate adjustment surface of the steel plate using rust preventive paints A to F to form a rust preventive coating film with a thickness of about 50 μm. The following 90-degree tape peeling test was performed on the rust preventive coating film surface. The rust preventive coating film on the substrate adjustment surface of the steel plate after the 90-degree tape peeling test was visually observed, and when no peeling of the rust preventive coating film was observed, it was described as "AA", and when partial peeling of the rust preventive coating film was observed, it was described as "BB". Also, before and after the 90-degree tape peeling test, the 85-degree specular gloss of the rust preventive coating film surface was measured according to the following conditions. The results are shown in Table 1.

[0107] <90-degree tape peeling test> As a cellophane adhesive tape conforming to JIS Z1522:2009, cellophane tape (registered trademark) (manufactured by Nichiban Co., Ltd., model number No. 405-1P, 24 mm width, adhesive strength: 3.93 N / 10 mm, tensile strength: 41.6 N / 10 mm, elongation: 23%, all of these physical property values are catalog values) was prepared. From the roll of cellophane adhesive tape, 25 cm was unwound under the environment of a temperature of 23 °C and a humidity of 50% RH, and with the adhesive surfaces of 10 cm pasted together to make a handle, 5 cm of the adhesive surface was adhered to the rust preventive coating film surface with a pressure roller of 2 kg mass reciprocated twice, and then adhered again by finger pressure so that no air was interposed. Next, the strong peeling of the cellophane adhesive tape was carried out once manually at a speed of 5 cm / s in a direction 90 degrees with respect to the rust preventive coating film surface. <85-degree specular glossiness> The 85-degree specular glossiness of the rust preventive coating film surface was measured under the conditions of an incident angle of 85 degrees and an observation angle of 85 degrees in accordance with Method 1 of JIS Z8741-1997. Using a gloss meter (manufactured by BYK, product name micro-TRI-gloss gloss meter), the 85-degree specular glossiness was measured 3 times and the average value was calculated.

[0108] Rust preventive paint A Alpha Paint Co., Ltd. Select Coat N300 Water-based silicone acrylic resin, one-component curing type, rust conversion type Rust preventive paint B Mie Paint Co., Ltd. Earth Coat Organic acid · Inorganic acid, one-component curing type, rust conversion type Rust preventive paint C Eco Clean Co., Ltd. Sabi Varier Epoxy resin, two-component curing type, rust conversion type Rust preventive paint D Eco Clean Co., Ltd. DecK Epoxy resin, two-component curing type, rust conversion type Rust preventive paint E Dainippon Paint Co., Ltd. Sabi Shut Urethane resin, two-component curing type, salt and iron ion detoxification type Rust preventive paint F Nippon Paint Co., Ltd. Hyponsabisuta Epoxy resin, two-component curing type, iron ion stabilization by two-component curing type ion trap agent

[0109] The urethane resin contained in the rust preventive paint E corresponds to a moisture-curing type resin. The rust preventive paint E corresponds to a two-component curing type urethane resin paint of the salt / iron ion detoxification type. The rust preventive paint F corresponds to a rust preventive paint of the type that prevents rust by stabilizing iron ions with a two-component curing type ion trap agent and does not contain a moisture-curing type resin.

[0110]

Table 1

[0111] In the same manner as above, a steel plate having a rusted part (red rust) was prepared. Three types of degreasing were performed on the steel plate. The steel plate after the three types of degreasing had a substrate adjustment surface including a live film (thickness: about 150 μm) of the old coating film and a rusted surface. Rust preventive treatments were performed on the substrate adjustment surface of the steel plate using rust preventive paints A to F to form rust preventive coating films with a thickness of about 50 μm.

[0112] An adhesive sheet was prepared which had a 300-μm-thick polyethylene layer, a polyethylene layer containing a glass mesh, a 300-μm-thick polyethylene layer, and a 1000-μm-thick acrylic-based composite adhesive layer (3M (registered trademark) VHB (registered trademark) tape for glass, high transparency Y-4910J) in this order. The acrylic-based composite adhesive layer had an acrylic-based adhesive layer, an acrylic resin layer, and an acrylic-based adhesive layer in this order. The storage elastic modulus (G') of the outermost acrylic-based adhesive layer at 40°C was 0.369 MPa. The storage elastic modulus was measured using a solid viscoelasticity measuring device (Solid Viscoelastic Analyzer RSA-III manufactured by TA Instruments) in accordance with the dynamic viscoelasticity measurement method (attachment mode: compression mode, frequency: 1 Hz, temperature: -50 to 200°C, heating rate: 5°C / min) conforming to JIS K7244-1:1998.

[0113] On the rust-preventive coating formation surface of the steel plate, in accordance with JIS Z0237:2022, the above-mentioned adhesive sheet with a width of 10 mm was attached in an environment of a temperature of 23°C and a humidity of 50% RH. At this stage, when the step-following property of the adhesive sheet with respect to the above-mentioned formation surface was confirmed, the above-mentioned adhesive sheet followed the steps well and was in close contact. After standing still in the above-mentioned environment for 3 days, 180-degree peeling of the adhesive sheet was carried out at a speed of 300 mm / min, and the peeling state of the adhesive sheet was confirmed. As a test device, a tensilon universal testing machine RTG-1250 was used. When the peeling state was confirmed, it was confirmed that cohesive failure occurred in the acrylic-based composite adhesive layer.

[0114] For the evaluation of the support of the adhesive sheet used in the repair method of the steel structure of the present disclosure, further tests were conducted. In the test, a laminate 55 having the layer structure shown in FIG. 2B was produced, and further, a support 52 having the layer structure shown in FIG. 3 was produced using the laminate 55. Then, evaluation tests of the produced laminate 55 and support 52 were conducted. In the example shown in FIG. 2B, the laminate 55 includes a resin layer 62 and a surface resin layer 63 in this order in the thickness direction. In the example shown in FIG. 3, the support 52 includes a gas barrier film 61, a resin layer 62, and a surface resin layer 63 in this order in the thickness direction. The support 52 further includes an adhesive layer 64 located between the gas barrier film 61 and the resin layer 62 for bonding the gas barrier film 61 and the resin layer 62.

[0115] The production of the laminate 55 shown in FIG. 2B and the support 52 shown in FIG. 3 was carried out as follows. First, 5 parts by mass of a weather-resistant masterbatch was mixed with 95 parts by mass of a base resin to obtain a resin composition. As the base resin, the density is 0.901 g / cm 3, a metallocene linear low density polyethylene resin (M-LLDPE) with a melting point of 93°C and an MFR of 2.0 g / 10 min at 190°C was used. As the weathering agent masterbatch, a mixture of 0.6 parts by mass of HALS ("KEMISTAB62" manufactured by Chemipro Kasei Co., Ltd.), 3.5 parts by mass of the first ultraviolet absorber, and 0.6 parts by mass of the second ultraviolet absorber was used per 100 parts by mass of the low density polyethylene resin. The density of the low density polyethylene resin in the weathering agent masterbatch was 0.880 g / cm 3 and its MFR (melt flow rate) at 190°C was 3.5 g / 10 min. As the HALS, "KEMISTAB62" manufactured by Chemipro Kasei Co., Ltd. was used. As the first ultraviolet absorber, "KEMISORB12" manufactured by Chemipro Kasei Co., Ltd. was used. As the second ultraviolet absorber, "KEMISORB79" manufactured by Chemipro Kasei Co., Ltd. was used.

[0116] Next, using a film forming machine having a φ30 mm extruder and a 200 mm wide T-die, the above resin composition was formed into a sheet at an extrusion temperature of 210°C. As a result, a resin layer 62 with a thickness of 300 μm was formed. The take-up speed when forming this sheet was adjusted so that the thickness of the formed resin layer 62 would be 300 μm. As the cooling roll directly below the T-die, a chromium-plated cooling roll with a surface roughness Rz of 1.5 μm was used. As the rubber roll directly below the T-die, a silicone rubber roll with a hardness of 70 degrees was used. The resin layer 62 was not colored and was transparent.

[0117] Next, one surface of the resin layer 62 was subjected to corona discharge treatment. Subsequently, 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 were mixed to prepare a resin composition for the primer layer. As the 100 parts by mass of the mixture, a mixture composed of a polycarbonate-based urethane-acrylic copolymer and an acrylic polyol was used. As the 5 parts by mass of the curing agent, hexamethylene diisocyanate was used. The prepared resin composition for the primer layer was applied to the treated surface of the resin layer 62 that had been subjected to corona discharge treatment. When applying the resin composition for the primer layer, the resin composition for the primer layer was applied to the treated surface by the gravure printing method and dried. Thereby, a primer layer having a thickness of 4 μm was formed on the treated surface of the resin layer 62.

[0118] Next, an ionizing radiation curable resin composition containing 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 was prepared. The prepared ionizing radiation curable resin composition was applied onto the primer layer to form an uncured resin layer on the primer layer. Subsequently, the uncured resin layer was cured by irradiating with an electron beam. As the electron beam, an electron beam having an acceleration voltage of 165 kV and an irradiation dose of 5 Mrad (50 kGy) was used. Thereby, a surface resin layer 63 having a thickness of 5 μm was formed from the uncured resin layer. The surface resin layer 63 and the resin layer 62 were adhered via a primer layer not shown in FIGS. 2B and 3. Thereby, the laminate 55 shown in FIG. 2B was produced.

[0119] Furthermore, a transparent urethane resin-based adhesive was applied to the surface of the resin layer 62 opposite to the surface on which the primer layer and the surface resin layer 63 were formed, and dried to form an adhesive layer 64 with a thickness of 3 μm. Furthermore, a gas barrier film 61 was prepared. As the gas barrier film 61, IB-PET-UB (manufactured by Dainippon Printing Co., Ltd.) was used. It can be said that IB-PET-UB is a gas barrier film 61 including a resin film and a gas barrier layer which is a vapor deposition film. Subsequently, the resin layer 62 and the gas barrier film 61 were adhered by dry laminating through the above adhesive layer 64. At this time, the resin layer 62 and the gas barrier film 61 were adhered so that the surface constituted by the gas barrier layer of the gas barrier film 61 faced the surface of the resin layer 62. Thus, the support 52 was produced.

[0120] <Weather resistance test> The support 52 and the adhesive sheet 50 including the support 52 preferably have weather resistance. Specifically, as shown in FIG. 1D, when the support 52 covers the rust preventive coating film 40, the support 52 may be able to protect the rust preventive coating film 40 from ultraviolet rays. In particular, it may be possible to suppress the deterioration of the materials contained in the rust preventive coating film 40 due to ultraviolet rays. The support 52 may be able to suppress the discoloration of the rust preventive coating film 40, particularly yellowing, due to ultraviolet rays. The support 52 may have resistance to ultraviolet rays so that the materials contained in the adhesive sheet 50 are not deteriorated by ultraviolet rays. As described above, when a topcoat film is provided on the surface of the adhesive sheet 50, the topcoat film can protect the rust preventive coating film 40 and the adhesive sheet 50 from ultraviolet rays. However, the case where no topcoat film is provided on the surface of the adhesive sheet 50 is also assumed. In this case, in particular, it is preferable that the support 52 can suppress the deterioration of the materials contained in the rust preventive coating film 40 due to ultraviolet rays. Furthermore, in this case, in particular, it is preferable that the support 52 has resistance to ultraviolet rays. As described above, the support 52 may contain an ultraviolet absorber as an additive. In this case, as described above, the surface resin layer 63 may contain an ultraviolet absorber. As described above, the resin layer 62 of the support 52 as shown in FIG. 3 may contain an ultraviolet absorber. As described above, the primer layer that adheres the surface resin layer 63 and the resin layer 62 of the support 52 as shown in FIG. 3 may contain an ultraviolet absorber. By the support 52 containing an ultraviolet absorber, the rust preventive coating film 40 can be protected from ultraviolet rays. Furthermore, resistance to ultraviolet rays can be imparted to the support 52. In particular, when the surface resin layer 63 contains an ultraviolet absorber, the portion of the rust preventive coating film 40 and the adhesive sheet 50 covered by the surface resin layer 63 can be protected from ultraviolet rays by the surface resin layer 63.

[0121] For the laminate 55 shown in Fig. 2B fabricated as described above, a weather resistance test was conducted. In this weather resistance test, a steel material 110 with a rust preventive coating film 140 formed thereon as shown in Fig. 4 was prepared. The thickness of the rust preventive coating film 140 was approximately 25 μm. Subsequently, as shown in Fig. 5, the laminate 55 and the rust preventive coating film 140 were adhered via an adhesive layer 154 to prepare a sample for the weather resistance test. At this time, the laminate 55 and the rust preventive coating film 140 were adhered such that the surface of the rust preventive coating film 140 faced the surface formed by the resin layer 62 of the laminate 55. As the adhesive layer 154, an acrylic adhesive was used. The thickness of the adhesive layer 154 was 80 μm.

[0122] Subsequently, a 408-hour weather resistance test was conducted on the sample for the weather resistance test. The weather resistance test was carried out using a weather resistance test apparatus. The 408-hour weather resistance test was performed as follows. For the sample for the weather resistance test, an irradiation step of irradiating ultraviolet rays for 20 hours from the side of the surface constituted by the surface resin layer 63 in Fig. 5 and a dew condensation step of 4 hours were taken as one cycle, and the cycle was repeatedly carried out until 408 hours were reached. A 30-second shower step was carried out before starting the dew condensation step after the irradiation step and before starting the irradiation step after the dew condensation step. In the shower step, the sample held in the weather resistance test apparatus was exposed to a water shower.

[0123] As the weather resistance test apparatus, the super accelerated weather resistance test apparatus "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 apparatus 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.

[0124] The conditions of the irradiation step were as follows. <Irradiation conditions> ·Black panel temperature: 63°C ·Illuminance: 100 mW / cm 2 · Humidity in the tank: 50%RH · Time: 20 hours

[0125] The conditions of the condensation process were set as follows. <Condensation conditions> · Illuminance: 0 mW / cm 2 · Humidity in the tank: 98%RH · Time: 4 hours

[0126] Then, the color difference ΔE of the rust preventive coating 140 before and after the weather resistance test was measured. The measured color difference ΔE is the L specified in JIS Z8781:2013 * a * b * In the color system, the color before the weather resistance test is L * 1 a * 1 b * 1 and the color after the weather resistance test is L * 2 a * 2 b * 2 and is defined by the following formulas (1) to (4).

Equation

[0127] The color L before the weather resistance test * 1 a * 1 b * 1 and the color L after the weather resistance test * 2 a * 2 b * 2 are the colors when observing the rust preventive coating 140 through the laminate 55.

[0128] Furthermore, as a sample of the comparative example, a steel material 110 with a rust preventive coating film 140 formed thereon as shown in FIG. 4 was prepared. For the sample of the comparative example, without covering the rust preventive coating film 140 with the laminate 55, a weather resistance test was conducted for 408 hours in the same manner as the sample shown in FIG. 5 described above, and the color difference ΔE of the rust preventive coating film 140 before and after the weather resistance test was measured. In the irradiation step of the weather resistance test of the sample of the comparative example, ultraviolet rays were irradiated from the side of the surface constituted by the rust preventive coating film 140 of the sample.

[0129] As a result of the measurement of the color difference ΔE, as shown in FIG. 5, in the sample where the rust preventive coating film 140 was covered with the laminate 55, the color difference ΔE before and after ultraviolet irradiation was 4.3. On the other hand, in the sample of the comparative example where the rust preventive coating film 140 was not covered with the laminate 55, the color difference ΔE before and after ultraviolet irradiation was 14.7. From this, as shown in FIG. 5, it was found that by covering the rust preventive coating film 140 with the laminate 55, the rust preventive coating film 140 can be protected from ultraviolet rays and the discoloration of the rust preventive coating film 140 can be suppressed. From this result, it was also clarified that even when the rust preventive coating film 140 was covered with the support 52 further provided with the gas barrier film 61 and the adhesive layer 64 in addition to the laminate 55, the rust preventive coating film 140 can be protected from ultraviolet rays and the discoloration of the rust preventive coating film 140 can be suppressed.

[0130] <Test of resistance to repeated wet and heat cycles> The support 52 preferably has resistance to repeated wet and heat cycles. More specifically, in the "Test of resistance to repeated wet and heat cycles" described in 7.18 of JIS K5659:2018, it is preferably evaluated as "resistant to repeated wet and heat cycles".

[0131] Regarding the support 52 shown in FIG. 3 fabricated as described above, a "test for repeated wet heat resistance" described in 7.18 of JIS K5659:2018 was conducted. As a result, the support 52 was evaluated as "resistant to repeated wet heat". Specifically, two test pieces were fabricated from the support 52 by the methods described in a) and b) of 7.16 of JIS K5659:2018. After immersing the two fabricated test pieces in water at 23°C ± 1°C for 18 hours, they were immediately cooled in a constant temperature bath maintained at -20 ± 3°C for 3 hours, and then humidified in another constant temperature bath maintained at 50 ± 3°C for 3 hours. This operation was repeated 10 times. These two test pieces were visually observed. At this time, no swelling, cracking, or peeling was observed in the coating film. Furthermore, when the gloss retention rate was calculated by the method described in b)2) of 7.18 of JIS K5659:2018, it was 80% or more.

[0132] When the two test pieces that had undergone 10 repetitions of the above-described operation were visually observed, no peeling was observed between the layers included in the support 52.

[0133] Regarding the test pieces that had undergone 10 repetitions of the above-described operation, a T-peel test was conducted in accordance with "Adhesives - Test methods for peel adhesion strength - Part 3: T-peel" of JIS K6854-3:1999. Thereby, the maximum point strength was measured regarding the peel adhesion strength in the adhesive layer 64. When the material of the test piece broke during the test, the breaking strength was measured as the maximum point strength, and when the material of the test piece did not break during the test, the maximum peel strength was measured as the maximum point strength. Furthermore, as a comparative example, a T-peel test similar to that of the test pieces that had undergone 10 repetitions of the above-described operation was conducted on test pieces that had not undergone 10 repetitions of the above-described operation. Thereby, the maximum point strength was also measured regarding the peel adhesion strength in the adhesive layer 64 of the test pieces of the comparative example. As a result, the maximum point strength of the test pieces that had undergone 10 repetitions of the above-described operation was 90% or more of the maximum point strength of the test pieces of the comparative example. From the above, even when a test for repeated wet heat resistance was conducted on the support 52 shown in FIG. 3, it was found that the decrease in the peel adhesion strength in the adhesive layer 64 was small.

[0134] <Topcoat Compatibility Test> As described above, it may be desirable to apply a topcoat paint to the surface of the adhesive sheet 50 to form a topcoat film. In this case, the support 52 constituting the surface of the adhesive sheet 50 preferably has topcoat compatibility. In this specification, the "topcoat compatibility" of the support 52 means the property of being able to apply a topcoat paint to the surface of the support 52 without any problem to form a topcoat film.

[0135] A topcoat compatibility test was conducted on the support 52 shown in FIG. 3 produced as described above. In this topcoat compatibility test, two test plates each having a size of 150 mm × 70 mm were produced from the support 52. A topcoat paint was applied to the surface of one of the test plates that is constituted by the surface resin layer 63. A baker-type applicator was used for applying the topcoat paint. Thereby, a test piece was produced. One of the test plates other than the test plate to which the topcoat paint was applied was used as an original state test piece without applying the topcoat paint.

[0136] Using the produced test piece, it was determined whether the support 52 has topcoat compatibility according to the method described in "Evaluation and Judgment" regarding "Topcoat Compatibility" described in c) of 7.11 of JIS K5551:2018. That is, the following three points 1) to 3) were confirmed. 1) When applying the topcoat paint to the surface of one of the test plates that is constituted by the surface resin layer 63, there is no problem with the topcoating operation. 2) After the topcoating (after applying the topcoat paint to the surface constituted by the surface resin layer 63), when the appearance of the formed topcoat film was visually observed after leaving it for 48 hours, no repellency, cracking, blistering, or peeling was observed in the topcoat paint. 3) When comparing the test piece left for 48 hours after the topcoating with the original state test piece produced at the same time and confirming by finger touch, the degree of adhesion is not increased, and when visually confirmed, the degree of wrinkle is not increased. When all of the above three points 1) to 3) are satisfied, it is considered that there is "no problem" in applying the topcoat paint to the surface of the support 52 to form a topcoat film. That is, when all of the above three points 1) to 3) are satisfied, it is determined that the support 52 has topcoat compatibility.

[0137] The above-mentioned topcoat compatibility test was conducted using an anti-fouling fluororesin topcoat paint (manufactured by Dainippon Paint Co., Ltd., product name "V-Freon #100H Smile Topcoat IG") as the topcoat paint. At this time, the target film thickness of the topcoat film was set to 25 μm. The actually measured film thickness of the formed topcoat film was 23.8 μm. Furthermore, the above-mentioned topcoat compatibility test was conducted using a weak solvent ultra-thick film epoxy resin paint (manufactured by Dainippon Paint Co., Ltd., product name "Eponix H-R Smile") as the topcoat paint. At this time, the target film thickness of the topcoat film was set to 150 μm. The actually measured film thickness of the formed topcoat film was 164.5 μm.

[0138] As a result of the topcoat compatibility test, it was determined that there was no problem in applying the topcoat paint to the surface of the support 52 to form a topcoat film regardless of whether an anti-fouling fluororesin topcoat paint or a weak solvent ultra-thick film epoxy resin paint was used as the topcoat paint. That is, it was determined that the support 52 had topcoat compatibility regardless of whether an anti-fouling fluororesin topcoat paint or a weak solvent ultra-thick film epoxy resin paint was used as the topcoat paint.

[0139] Furthermore, for the topcoat film prepared in the topcoat compatibility test, after applying the topcoat paint and leaving it for 48 hours, the above-mentioned 90-degree tape peel test was conducted on the topcoat film of the test piece. That is, 25 cm was unwound from a roll of 24 mm wide cellophane adhesive tape conforming to JIS Z1522:2009 under an environment of a temperature of 23°C and a humidity of 50% RH. To create a handle, 10 cm of the adhesive surfaces were bonded together. In this state, 5 cm of the adhesive surface was attached to the surface of the topcoat film with a 2 kg pressure roller reciprocated twice, and then further attached by finger pressure again so that no air intervened. Next, a strong peel of the cellophane adhesive tape was manually performed once at a speed of 5 cm / s in a 90-degree direction with respect to the surface of the topcoat film. As the above cellophane adhesive tape, Cellotape (registered trademark) (manufactured by Nichiban, model number No. 405-1P, 24 mm wide, adhesive strength: 3.93 N / 10 mm, tensile strength: 41.6 N / 10 mm, elongation: 23%, all of these physical property values are catalog values) was used. When this product cannot be used, a 90-degree tape peel test can be conducted on the topcoat film by using a 24 mm wide cellophane adhesive tape conforming to JIS Z1522:2009 and having an adhesive strength equivalent to that of this product.

[0140] As a result of the 90-degree tape peel test on the topcoat film, even when a strong peel of the cellophane adhesive tape was performed once, the topcoat film did not peel off.

[0141] <Image sharpness> From the viewpoint of suppressing the reflection of external objects on the surface of the adhesive sheet, it is preferable that the image sharpness (%) by the reflection method on the first surface of the adhesive sheet is small. For the laminate 55 shown in Fig. 2B prepared as described above, an image sharpness measurement test was conducted. In this image sharpness measurement test, in the same manner as described above in the weather resistance test, a sample having a steel material 110, a rust-preventive coating film 140 formed on the steel material 110, and a laminate 55 covering the rust-preventive coating film 140 as shown in Fig. 5 was prepared. The above-mentioned rust-preventive paint F was used for the formation of the rust-preventive coating film 140.

[0142] The image sharpness (%) by the reflection method on the surface of this sample constituted by the surface resin layer 63 was measured. The image sharpness (%) was measured in accordance with JIS K7374:2007. As the image sharpness (%), the image sharpness (%) when the brush width was 1.0 mm was measured. The incident angle of the light incident on the incident surface (the surface of the sample constituted by the surface resin layer 63) during the measurement was set to 60°. For the measurement of the image sharpness (%), an image property measuring instrument ICM-1T manufactured by Suga Test Instruments Co., Ltd. was used.

[0143] As a result of the measurement of the image sharpness (%), a measurement result of 12.8% was obtained. From this, it was found that the image sharpness when the brush width was 1.0 mm on the surface of the laminate 55 constituted by the surface resin layer 63 was suppressed to 20% or less.

[0144] The present disclosure relates to, for example, the following [1] to

[13] . [1] A method for repairing a steel structure having a deteriorated portion, comprising: a first step of preparing an adhesive sheet including a support and an adhesive layer provided on one surface of the support; a second step of performing substrate conditioning on the deteriorated portion of the steel structure to form a substrate conditioning surface that may have an active film; a third step of performing a rust prevention treatment on the substrate conditioning surface of the steel structure to form a rust prevention treatment surface; and a fourth step of disposing the adhesive sheet on the rust prevention treatment surface of the steel structure. [2] The method for repairing a steel structure according to [1], wherein the second step is a step of performing at least a substrate conditioning of three types of keren on the deteriorated portion of the steel structure. [3] The method for repairing a steel structure according to [1] or [2], wherein the third step is a step of applying a rust prevention paint to the substrate conditioning surface of the steel structure to form a rust prevention paint film. [4] The method for repairing a steel structure according to [3], wherein the rust prevention paint is a two-component curable rust prevention paint. [5] When the 85-degree specular gloss of the rust-preventive coating surface before performing the 90-degree tape peeling test on the rust-preventive coating surface is denoted as Gsb, and the 85-degree specular gloss of the rust-preventive coating surface after performing the 90-degree tape peeling test on the rust-preventive coating surface is denoted as Gsa, the maintenance rate (Gsa×100 / Gsb) is 95% or more, and the repair method of the steel structure according to [3] or [4] above. [6] The repair method of the steel structure according to any one of [1] to [5] above, further including a 3a step of forming a coating resin layer on the rust-preventive treatment surface between the third step and the fourth step. [7] The repair method of the steel structure according to any one of [1] to [6] above, further including a fifth step of forming a topcoat film on the surface of the adhesive sheet disposed on the rust-preventive treatment surface. [8] The repair method of the steel structure according to any one of [1] to [7] above, wherein the adhesive sheet includes a composite adhesive layer including a first adhesive layer, a base material layer, and a second adhesive layer in this order in the thickness direction. [9] The repair method of the steel structure according to any one of [1] to [8] above, wherein the support of the adhesive sheet includes a gas barrier layer.

[10] The repair method of the steel structure according to [9] above, wherein the oxygen permeability of the adhesive sheet measured under the environment of a temperature of 23°C and a humidity of 60%RH in accordance with JIS K7126-2:2006 is 6.57 cc / (m2·day·atm) or less.

[11] The repair method of the steel structure according to [9] or

[10] above, wherein the water vapor permeability of the adhesive sheet measured under the environment of a temperature of 40°C and a humidity of 90%RH in accordance with JIS K7129-2:2019 is 3.0 g / (m2·day) or less.

[12] The repair method of the steel structure according to any one of [1] to

[11] above, wherein the total light transmittance of the adhesive sheet is 70% or more.

[13] The repair method of the steel structure according to

[12] above, wherein the haze of the adhesive sheet is 97% or more.

[14] The adhesive sheet has a first surface which is the surface opposite to the surface facing the steel structure when the adhesive sheet is disposed on the rust prevention treated surface of the steel structure. The method for repairing a steel structure according to

[12] or

[13] , wherein the image sharpness (%) by the reflection method on the first surface of the adhesive sheet is 20% or less when the brush width is 1.0 mm.

[15] A method for manufacturing a steel structure, wherein the method for repairing a steel structure according to any one of [1] to

[14] is applied to a steel structure having a deteriorated portion to manufacture a repaired steel structure.

[16] An adhesive sheet for repairing a steel structure, comprising a support and an adhesive layer provided on one surface of the support, for being disposed on a rust prevention treated surface where substrate adjustment and rust prevention treatment have been performed on the deteriorated portion of the steel structure having a deteriorated portion.

[17] The adhesive sheet for repairing a steel structure according to

[16] , wherein the adhesive sheet comprises a composite adhesive layer including a first adhesive layer, a base material layer, and a second adhesive layer in this order in the thickness direction.

Explanation of reference numerals

[0145] 10 ··· Steel material, 20 ··· Coating film before repair (old coating film), 22 ··· Activated film, 30 ··· Rust, 40 ··· Rust prevention coating film, 50 ··· Adhesive sheet, 52 ··· Support, 54 ··· Adhesive layer

Claims

1. A method for repairing a steel structure having a deteriorated portion, comprising: a first step of preparing an adhesive sheet having a support and an adhesive layer provided on one surface of the support; A second step of performing a surface preparation process on the deteriorated portion of the steel structure to form a surface preparation surface which may have an active film; A third step of performing a rust-proofing treatment on the base preparation surface of the steel structure to form a rust-proofed surface having irregularities; A fourth step of placing the adhesive sheet so as to be in direct contact with the rust-proofing surface of the steel structure; A method for repairing a steel structure, comprising:

2. 2. The method for repairing a steel structure according to claim 1, wherein the second step is a step of at least performing surface preparation using a three-type surface preparation method on the deteriorated portion of the steel structure.

3. 2. The method for repairing a steel structure according to claim 1, wherein the third step is a step of applying an anti-rust paint to the base preparation surface of the steel structure to form an anti-rust coating film.

4. 4. The method for repairing a steel structure according to claim 3, wherein the anti-rust paint is a two-component curing type anti-rust paint.

5. 4. The method for repairing a steel structure as described in claim 3, wherein the 85 degree specular gloss of the anti-rust coating film surface before a 90 degree tape peel test is performed on the anti-rust coating film surface is designated as Gsb, and the 85 degree specular gloss of the anti-rust coating film surface after a 90 degree tape peel test is performed on the anti-rust coating film surface is designated as Gsa, and the maintenance rate (Gsa x 100 / Gsb) is 95% or more.

6. 2. The method for repairing a steel structure according to claim 1, further comprising a step 3a between the third step and the fourth step of forming a coating resin layer on the rust-proofed surface.

7. 2. The method for repairing a steel structure according to claim 1, further comprising a fifth step of forming a topcoat film on the surface of the adhesive sheet placed on the rust-proofed surface.

8. The method of repairing a steel structure according to claim 1 , wherein the support of the adhesive sheet comprises a gas barrier layer.

9. 9. The method for repairing a steel structure according to claim 8, wherein the adhesive sheet has an oxygen permeability of 6.57 cc / (m2·day·atm) or less, measured in accordance with JIS K7126-2:2006 at a temperature of 23°C and a humidity of 60% RH.

10. The method for repairing a steel structure according to claim 8, wherein the adhesive sheet has a water vapor permeability of 3.0 g / (m2·day) or less, measured in accordance with JIS K7129-2:2019 at a temperature of 40°C and a humidity of 90% RH.

11. The method for repairing a steel structure according to claim 1 , wherein the adhesive sheet has a total light transmittance of 70% or more.

12. The method for repairing a steel structure according to claim 11 , wherein the adhesive sheet has a haze of 97% or less.

13. the adhesive sheet has a first surface which is a surface opposite to a surface which faces the steel structure when the adhesive sheet is placed on the rust-proofing surface of the steel structure; 12. The method for repairing a steel structure according to claim 11, wherein an image clarity (%) on the first surface of the adhesive sheet by a reflection method is 20% or less when the comb width is 1.0 mm.

14. A manufacturing method for a steel structure, comprising applying the steel structure repair method according to any one of claims 1 to 13 to a steel structure having a deteriorated portion to manufacture a repaired steel structure.

15. An adhesive sheet for repairing a steel structure, comprising a support and an adhesive layer provided on one surface of the support; A steel structure having an anticorrosive treated surface having projections and recesses; A repaired steel structure, wherein the repair adhesive sheet is placed so as to be in direct contact with the rust-proofed surface of the steel structure.

Images