Bolt-nut cap and method for protecting or repairing bolt-nut and steel structure using the same

Abstract

To provide a bolt-nut cap that has an easy manufacture process and exhibits superior workability and weather resistance.SOLUTION: The present invention provides a bolt-nut cap formed by injection molding of a composition containing a thermoplastic resin composed of at least one selected from the group consisting of a polyimide resin, a polyacrylate resin, a polyvinyl chloride resin, a polycarbonate resin, a polyethylene terephthalate resin, a polyamide resin, and an acrylonitrile-butadiene-styrene copolymer, wherein the transmittance in a UV wavelength range of 315 to 380 nm is equal to or lower than 10%, and the yellowness index after exposure for 2000 hours using a xenon arc lamp in an accelerated weathering test performed in accordance with ISO 4892-2 is equal to or lower than 2.0. The present invention also provides a method for protecting or repairing one or both of a bolt and a nut using the bolt-nut cap, and a method for protecting or repairing a steel structure.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a bolt and nut cap for covering a protruding portion of a bolt and / or nut installed indoors or outdoors from a joint surface, and also to a method for protecting or repairing a bolt, nut, and steel structure using the bolt and nut cap. [Background technology]

[0002] Steel structures, such as bridges, water gates, buildings, marine structures, and plants, whose main components are made of steel, are fastened using bolts and nuts. When using this bolt-nut connection, the bolt head and nut generally protrude from the joint surface, and are therefore susceptible to deterioration factors such as sunlight, wind, rain, and sea air, and gradually deteriorate, leading to rust and corrosion, which impairs the function of the steel structure. Although the surfaces of the bolt head and nut protruding from the joint surface are coated with anticorrosive paint, the surfaces of the bolt and nut often have complex shapes, making it difficult to paint uniformly, and therefore not only is it difficult to ensure an appropriate paint thickness, but rainwater and flying salt are likely to accumulate, which causes the anticorrosive paint near the bolt and nut to peel off, and the deterioration is likely to progress.

[0003] In view of this, a method has been considered in which the protruding parts of the bolt and nut are covered with a resin cap (bolt and nut cap) to protect the bolt and nut and prevent rust from occurring (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-038764 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology described in Patent Document 1 requires that at least a fluorine-based resin layer and a thermoplastic resin layer that does not contain fluorine-based resin be provided in that order, and while this can be realized for a flat shape, there is a problem in that it is difficult to control the thickness of each resin layer when making a complex cap shape.

[0006] In addition, when a flat base material is thermoformed, the thickness of the shoulder part connecting the top plate and the body becomes thin, which is problematic. The thin part has poor strength and weather resistance, and there is a risk that ultraviolet rays and oxygen may easily pass through.

[0007] The present invention has been made in view of the above problems, and aims to provide a bolt / nut cap that is easy to manufacture and has excellent workability and weather resistance, and also aims to propose a method for protecting or repairing bolts and nuts and steel structures using the bolt / nut cap. [Means for solving the problem]

[0008] The bolt and nut cap of the present invention, which advantageously solves the above problems, is a bolt and nut cap formed by injection molding a composition containing at least one thermoplastic resin selected from the group consisting of polyimide resin, polyacrylic ester resin, polyvinyl chloride resin, polycarbonate resin, polyethylene terephthalate resin, polyamide resin, and acrylonitrile-butadiene-styrene copolymer, and is characterized in that the transmittance in the ultraviolet wavelength range of 315 to 380 nm is 10% or less, and the yellowing index after an accelerated weathering test in which a 2000-hour exposure test is performed using a xenon arc lamp in accordance with ISO4892-2 is 2.0 or less.

[0009] In addition, the bolt and nut cap of the present invention is, (a) A container having a hemispherical or disc-shaped top portion, a cylindrical body portion whose entire circumference is connected to one end of the top portion without any corners, and an annular flange portion whose entire circumference is connected to the other end of the body portion, The thickness tolerance of the top and body parts is within the range of -15% to +15%. (b) The total light transmittance in the visible light range measured in accordance with the measurement method specified in JIS K7361-1-1997 is 75% or more. (c) The tensile strength after an accelerated weathering test in accordance with ISO 4892-2, in which an exposure test is performed for 20,000 hours using a xenon arc lamp, is 80% or more of the tensile strength before the test. This may be a preferred solution.

[0010] The method for protecting or repairing one or both of a bolt and a nut according to the present invention, which advantageously solves the above-mentioned problem, is characterized in that it includes using an adhesive to fix any of the bolt and nut caps described above so as to cover the protruding portions of one or both of the bolt and the nut.

[0011] The method for protecting or repairing a steel structure of the present invention, which advantageously solves the above-mentioned problem, is a method for protecting or repairing a steel structure comprising a steel material and bolts and nuts fixed to the steel material, and is characterized in that it includes the steps of using a flat corrosion protection sheet having an adhesive on one side and applying the adhesive-bearing side of the flat corrosion protection sheet to the flat surface of the steel material excluding the bolts and nuts and the edges of the steel material, using a Z-shaped corrosion protection sheet having an adhesive on the inner or outer surface of a Z-shaped cross section and applying the adhesive-bearing side of the Z-shaped corrosion protection sheet from below or above the flat corrosion protection sheet so as to follow the edges of the steel material, and fixing any of the above-mentioned bolt and nut caps onto the flat corrosion protection sheet using an adhesive so as to cover the protruding portions of one or both of the bolts and nuts.

[0012] In addition, the method for protecting or repairing a steel structure according to the present invention can be preferably solved by the fact that the flat corrosion protection sheet and the Z-shaped corrosion protection sheet have a fluororesin layer on the outer surface and a thermoplastic resin layer on the surface to which an adhesive is applied, have a transmittance of 10% or less in the ultraviolet wavelength range of 315 to 380 nm, a total light transmittance of 75% or more in the visible light range measured in accordance with the measurement method specified in JIS K7361-1-1997, and a thickness in the range of 30 to 2000 μm. Effect of the Invention

[0013] The bolt and nut cap of the present invention has excellent weather resistance and high ultraviolet shielding power, so that deterioration of painted bolts and nuts and adhesives is small. The bolt and nut cap has a uniform thickness, so that deterioration of strength and weather resistance is unlikely to occur, which is preferable. The bolt and nut cap has excellent visible light transmittance, so that it is easy to observe the change over time of bolts and nuts. [Brief description of the drawings]

[0014] [Figure 1] 1A and 1B are drawings showing an example of a bolt and nut cap according to the present invention, where (a1) and (a2) are a front view and a plan view of Type A, and (b1) and (b2) are a front view and a plan view of Type B. [Diagram 2] FIG. 4 is a schematic cross-sectional view showing an example of use of the bolt and nut cap according to the embodiment. [Diagram 3] FIG. 1 is a perspective view showing an example in which the bolt and nut cap according to the embodiment is used to protect a bolt and a nut. [Figure 4] 1 is a graph comparing discoloration levels (yellowing) of plastics after weather resistance testing in accordance with ISO4892-2. [Diagram 5] 1 is a graph comparing the transition of tensile strength after the weather resistance test. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, the embodiments of the present invention will be described in detail with reference to the drawings. Note that the following embodiments are merely examples of products and methods for embodying the technical idea of ​​the present invention, and are not intended to limit the configuration to the following. In other words, the technical idea of ​​the present invention can be modified in various ways within the technical scope described in the claims.

[0016] <1. Bolt, nut and cap> (1.1 Composition) The bolt and nut cap according to the present embodiment is formed by injection molding a composition containing a thermoplastic resin. This composition contains one or more thermoplastic resins. In order to ensure transparency and moldability, it is preferable that the total content of the thermoplastic resins in the composition is 70 mass% or more.

[0017] The thermoplastic resin contains at least one selected from the group consisting of polyimide resin, poly(meth)acrylic acid ester resin, polyvinyl chloride resin, polycarbonate resin (PC resin), polyethylene terephthalate resin, polyamide resin, and acrylonitrile-butadiene-styrene copolymer (ABS resin). It is preferable that the thermoplastic resin does not contain a fluororesin.

[0018] Examples of polyvinyl chloride resins include polyvinyl chloride, chlorinated polyethylene, and resins obtained by copolymerizing vinyl chloride with a comonomer component (e.g., vinyl chloride-vinyl acetate copolymer, vinyl chloride-ethylene copolymer, vinyl chloride-propylene copolymer). Polyvinyl chloride resins may be used alone or in combination of two or more kinds.

[0019] Polyimide resin is a resin made of aromatic polyimide, which is a compound directly linked by imide bonds. Aromatic polyimide has a rigid and strong molecular structure because aromatics have a conjugated structure through imide bonds, and because imide bonds have strong intermolecular forces, it has the highest level of thermal, mechanical, and chemical properties of all polymers. It can be synthesized by a two-step method in which polyamide is dehydrated and cyclized by heating or using a catalyst, or by a one-step method in which tetracarboxylic dianhydride and diisocyanate are directly reacted.

[0020] Polycarbonate resins are resins in which the bonds between monomers are mainly carried out by carbonate groups. Examples of polycarbonate resins include those obtained by reacting one or more bisphenols with phosgene or carbonic acid diesters, or those obtained by reacting one or more bisphenols with diphenyl carbonates by transesterification. Examples of the bisphenols include bis-(4-hydroxyphenyl)-alkanes such as bisphenol A, bis-(4-hydroxyphenyl)-cycloalkanes, bis-(4-hydroxyphenyl)-sulfides, bis-(4-hydroxyphenyl)-ethers, bis-(4-hydroxyphenyl)-ketones, bis-(4-hydroxyphenyl)-sulfones, and bisphenol fluorene. In addition, for the purpose of improving processing characteristics, those obtained by copolymerizing compounds such as hydroquinone and 4,4-dihydroxybiphenyl as dihydric phenols other than bisphenols as copolymers are also preferably used. The polycarbonate resins may be used alone or in combination of two or more kinds.

[0021] Polyethylene terephthalate resins are resins whose main monomer components are terephthalic acid as a dicarboxylic acid component and ethylene glycol as a diol component. Other comonomer components may be copolymerized to suppress crystallization during molding, improve processability, etc. Specific examples of comonomer components include isophthalic acid, sebacic acid, adipic acid, azelaic acid, etc. as dicarboxylic acid components, and diethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, butanediol, etc. as diol components. The polyethylene terephthalate resins may be used alone or in combination of two or more.

[0022] Polyamide resins are resins in which the amide group is mainly responsible for bonding between monomers. As the polyamide resins, any of aliphatic polyamide resins, alicyclic polyamide resins, and aromatic polyamide resins can be used. As the aliphatic polyamides, polyamide 46, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 9, polyamide 10, polyamide 11, polyamide 12, polyamide 13, polyamide 14, polyamide 15, polyamide 16, polyamide 17, polyamide 18, polyamide 19, polyamide 20, polyamide 21, polyamide 22, polyamide 23, polyamide 24, polyamide 25, polyamide 26, polyamide 27, polyamide 28, polyamide 29, polyamide 30, polyamide 31, polyamide 32, polyamide 33, polyamide 34, polyamide 35, polyamide 36, polyamide 37, polyamide 38, polyamide 39, polyamide 40, polyamide 41, polyamide 42, polyamide 43, polyamide 44, polyamide 45, polyamide 46, polyamide 47, polyamide 48, polyamide 49 ...9, polyamide 41, polyamide 42, polyamide 43, polyamide 44, polyamide 45, polyamide 46, polyamide 46, polyamide 46, polyamide 46, polyamide 46, polyamide 47, polyamide 48, polyamide 49, polyamide 49, polyamide 49, polyamide 49, polyamide 49, polyamide 49 Examples of the polyamides include amide 11, polyamide 12, polyamide 6 / 66, and polyamide 66 / 610. Examples of the alicyclic polyamides include poly-1,4-norbornene terephthalamide, poly-1,4-cyclohexane terephthalamide, and poly-1,4-cyclohexane-1,4-cyclohexanamide. Examples of the aromatic polyamides include polyamide 4T, polyamide 5T, polyamide M-5T, polyamide 6T, polyamide 9T, polyamide 10T, polyamide 11T, polyamide 12T, polyamide MXD6, polyamide PXD6, polyamide MXD10, polyamide 6I, polyamide PACMT, polyamide PACMI, polyamide PACM12, and polyamide PACM14. The polyamide resins may be used alone or in combination of two or more.

[0023] Acrylonitrile-butadiene-styrene copolymer (ABS resin) is a general term for resins obtained by copolymerization using acrylonitrile, butadiene, and styrene as raw material monomers, and any ratio of each component can be used. Raw material monomers used for ABS resins include those containing monomers such as α-methylstyrene, vinyltoluene, dimethylstyrene, chlorostyrene, and vinylnaphthalene in addition to or in place of styrene. Also includes those containing monomers such as methacrylonitrile, ethacrylonitrile, and fumaronitrile in addition to or in place of acrylonitrile. Also includes those containing monomers such as acrylic rubber mainly composed of (meth)butyl acrylate, chlorinated polyethylene, and ethylene-propylene-diene rubber (EPDM), which is an ethylene-based rubber, in addition to or in place of butadiene. Therefore, in this specification, ABS resin is a concept that includes AES resin, ASA resin, ACS resin, and the like.

[0024] The polymerization method for acrylonitrile-butadiene-styrene copolymer (ABS resin) can be any method. The most common method for producing ABS resin is the graft copolymerization method in which acrylonitrile-styrene copolymer is grafted to polybutadiene, but ABS resin polymerized by, for example, emulsion grafting method, bulk polymerization method, polymer blend method, etc. can also be used.

[0025] In the emulsion grafting method, acrylonitrile, latex, styrene, catalyst, and emulsifier are polymerized in a polymerization reactor, water and other substances are removed using a centrifuge, and the materials are pelletized in an extruder. In the bulk polymerization method, each is polymerized in a polymerization reactor, the unpolymerized monomers are recovered, and the materials are pelletized in an extruder. In the polymer blend method, rubber and additives are added to AS resin, the mixture is compounded in a mixer, and the mixture is pelletized in an extruder. Another type of method is to produce ABS resin with an extremely high butadiene ratio using the grafting method and compound it with AS resin.

[0026] As the ABS resin, any resin containing ABS resin as a main component, such as an ABS resin blend or an ABS resin alloy, can be used. Examples of such resins include PC / ABS resin, which is a blend of PC resin and ABS resin. In addition, a styrene-N-phenylmaleimide-maleic anhydride copolymer may be blended with the ABS resin to improve the heat resistance of the ABS resin and to improve the compatibility of the PC / ABS resin blend or the polyamide / ABS resin blend.

[0027] The composition according to the present embodiment may appropriately contain other resins, plasticizers, heat stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, crystal nucleating agents, antiblocking agents, sealability improvers, release agents, colorants, pigments, foaming agents, flame retardants, etc., within the scope of the present invention. However, generally, the total content concentration of polyimide resins, poly(meth)acrylic acid ester resins, polyvinyl chloride resins, polycarbonate resins, polyethylene terephthalate resins, polyamide resins, and acrylonitrile-butadiene-styrene copolymers (ABS resins) in the composition according to the present embodiment is 70% by mass or more, typically 80% by mass or more, and more typically 90% by mass or more.

[0028] The flange portion of the bolt nut cap may be superimposed on the anticorrosive sheet, as described later. Therefore, the surface of the composition according to this embodiment that comes into contact with the anticorrosive sheet, that is, the base material contact surface, may be surface-treated, for example, by corona discharge treatment, plasma treatment (atmospheric pressure and vacuum), high-frequency sputter etching treatment, frame treatment, Itro treatment, excimer UV treatment, primer treatment, etc., in order to increase the adhesive strength with the adhesive sheet sandwiched between the anticorrosive sheet. In addition, roughening treatment such as physically scraping the surface with sandpaper, scraping, blasting, etc. may be performed. Examples of primers include acrylic, ethylene vinyl acetate, urethane, and epoxy, and acrylic is preferred from the viewpoint of increasing the adhesive strength with the anticorrosive sheet.

[0029] (1.2 UV absorption performance) The bolt nut cap according to the present embodiment is characterized in that the composition contains an ultraviolet absorbing agent and has a transmittance of 10% or less in the ultraviolet wavelength region of 315 to 380 nm. This improves the weather resistance of the composition constituting the bolt nut cap. In addition, it is possible to suppress deterioration of paint applied to the bolts and nuts and steel structures protected by the bolt nut cap. Furthermore, it is possible to suppress deterioration of the adhesive used for bonding the base material contact surface of the bolt nut cap to the anticorrosive sheet or the like. The transmittance of the ultraviolet wavelength region of 315 to 380 nm is preferably 7% or less, more preferably 5% or less, and may be 0.

[0030] The ultraviolet absorbent can be selected in consideration of ultraviolet absorbing ability and compatibility with the composition to be used. For example, hydroquinone-based, benzotriazole-based, benzophenone-based, triazine-based, cyanoacrylate-based, etc. can be mentioned. These may be used alone or in combination of two or more. The content of the ultraviolet absorbent in the composition is preferably 0.05 to 15 mass%. By making the content of the ultraviolet absorbent 0.05 mass% or more, preferably 1 mass% or more, and more preferably 2 mass% or more, it is possible to expect a further improvement effect in weather resistance, an ultraviolet absorbing effect, and an effect of suppressing deterioration of the coating and steel surface by imparting UV cut properties. By making the content of the ultraviolet absorbent 15 mass% or less, preferably 10 mass% or less, and more preferably 5 mass% or less, it is possible to prevent the ultraviolet absorbent from bleeding out onto the surface of the composition, prevent a decrease in adhesion with the adhesive, and realize cost reduction.

[0031] Furthermore, a light stabilizer may be added, and the light stabilizer may be selected in consideration of the compatibility with the composition to be used, the thickness, etc. Examples of the light stabilizer include hindered amine compounds, hindered phenol compounds, benzoate compounds, nickel complex compounds, etc. These may be used alone or in combination of two or more.

[0032] (1.3 Bolt-nut-cap configuration example) Hereinafter, configuration examples of the bolt and nut cap will be described with reference to Figs. 1(a1) and (a2) show a front view and a plan view of a type A bolt nut cap (1A) according to an example of this embodiment. The type A bolt nut cap includes a hemispherical top portion (11A), a cylindrical body portion (13A) in which the top portion (11A) is connected to one end of the entire circumference without having corners, an opening portion (15A) for introducing the protruding portion (50) of the nut and bolt into the body portion (13A), and a flange portion (14A) bonded to the flat portion (41B) to which the bolt and nut are fixed. The washer (50A), the nut (50B), and the tip (50C) of the bolt are all surrounded within the internal space formed by the top portion (11A) and the body portion (13A). The flange portion (14A) has a shape extending radially from the opening portion (15A).

[0033] 1(b1) and (b2) show a front view and a plan view of a bolt nut cap (1B) of type B according to another embodiment of the present invention. The bolt nut cap of type B includes a circular top portion (11B), a shoulder portion (12B) that connects the top portion (11B) and the body portion (13B) all around without any corners, a cylindrical body portion (13B), an opening portion (15B) for introducing the head portion (50D) of the bolt into the body portion (13B), and a flange portion (14B) that is bonded to the flat portion (41C) to which the bolt is fixed. The washer (50A) and the head portion (50D) of the bolt are surrounded within the internal space formed by the top portion (11B), the shoulder portion (12B), and the body portion (13B). The flange portion (14B) has a shape that extends radially from the opening portion (15B).

[0034] (1.4 Transparency) The bolt nut cap according to the present embodiment has a total light transmittance of 75% or more, more preferably 85% or more (for example, 90 to 99%), measured according to the measurement method specified in JIS K7361-1-1997. The bolt nut cap according to the present embodiment has a haze of 60% or less, more preferably 50% or less, even more preferably 40% or less, even more preferably 30% or less, even more preferably 20% or less, even more preferably 10% or less, and most preferably 5% or less, for example, in the range of 0.1 to 60%. The total light transmittance and haze are parameters related to transparency, and a high total light transmittance and low haze indicate that the transparency of the bolt nut cap is high. As a result, even when the protruding parts of the bolt and / or nut are covered with the bolt nut cap, deterioration of the protruding parts can be visually confirmed, which makes it easier to carry out deterioration prediction maintenance work for the structure to which the bolt and / or nut is fixed. The total light transmittance and haze of the bolt / nut cap are measured by cutting out any part of the bolt / nut cap. For example, a flat part such as the disk-shaped top part (11B) or flange parts (14A, 14B) of the bolt / nut cap is preferable.

[0035] (1.5 bolt nut cap thickness) In the bolt nut cap (1A, 1B) of this embodiment, the thickness tolerance of the top portion (11A, 11B), shoulder portion (12B) and body portion (13A, 13B) is preferably in the range of -15% to +15%. More preferably, it is in the range of -10% to +10%, and even more preferably, it is in the range of -5% to +5%. This allows stable weather resistance and uniform strength to be obtained. From the viewpoint of the shape retention and strength of the bolt nut cap, the thickness of the bolt nut cap is preferably 50 μm or more at the thinnest point, more preferably 100 μm or more, even more preferably 500 μm or more, and particularly preferably 1,000 μm or more. On the other hand, from the viewpoints of moldability, shape retention, strength and cost, the thickness of the bolt nut cap is preferably 3,000 μm or less at the thickest point, more preferably 2,500 μm or less, and even more preferably 2,000 μm or less. Therefore, the thickness of the bolt / nut cap according to this embodiment can be in the range of 50 to 3,000 μm. Note that the thickest point of the bolt / nut cap is specified from the point excluding the flange portion.

[0036] (1.6 Weather resistance) The material used for the bolt and nut caps (1A, 1B) of this embodiment is in accordance with SO4892-2 and has a yellowing index of 2.0 or less after 2000 hours of accelerated weather resistance testing using a xenon arc lamp. It is preferably 1.5 or less. The smaller the yellowing index, the better the weather resistance.

[0037] Moreover, it is preferable that the material used for the bolt and nut caps (1A, 1B) of this embodiment has a small change in strength when a tensile strength test is performed before and after the accelerated weather resistance test similar to that described above. For example, it is preferable that the tensile strength after a 2000-hour accelerated weather resistance test by exposure using a xenon arc lamp is 80% or more of the tensile strength before the test. More preferably, it is 90% or more, and even more preferably, it is 95% or more. Most preferably, the tensile strength after a 20000-hour accelerated weather resistance test by exposure using a xenon arc lamp is 95% or more of the tensile strength before the test.

[0038] (1.7 Adhesives) When the base material contact surface of the bolt nut cap according to this embodiment is adhered to the flat surface side of the steel material to which the bolt or nut is fixed, it may be covered with a corrosion prevention sheet described later to protect the flat surface. In that case, a pressure-sensitive adhesive is interposed to obtain adhesion between the thermoplastic resin, which is the composition of the bolt nut cap, and the fluororesin of the surface layer of the corrosion prevention film. In this embodiment, the pressure-sensitive adhesive refers to a pressure-sensitive adhesive, an adhesive, or a mixture of both. In this embodiment, the difference between the pressure-sensitive adhesive and the adhesive is that the pressure-sensitive adhesive is a gel-like soft solid from the time of lamination, and spreads wetly on the adherend in its original state, and thereafter does not change in state and exerts a force to resist peeling. In other words, the pressure-sensitive adhesive exerts an adhesive force that can withstand practical use immediately after lamination, whereas the adhesive is a fluid liquid that wets and spreads at the lamination interface when lamination is performed, and then changes to a solid by chemical reaction, and is firmly bound at the interface, exerting a force to resist peeling. After lamination, the adhesive needs time for the adhesive to solidify by chemical reaction before it exerts an adhesive force that can withstand practical use. The type of pressure-sensitive adhesive to be used may be appropriately determined according to the materials of the fluororesin layer and the thermoplastic resin.

[0039] Examples of the adhesive include rubber-based adhesives, (meth)acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinyl pyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Such adhesives may be used alone or in combination of two or more.

[0040] Pressure sensitive adhesives can be classified according to their adhesive form into hot melt pressure sensitive adhesives, two-component mixture pressure sensitive adhesives, heat curing pressure sensitive adhesives, UV curing pressure sensitive adhesives, etc. Among these, two-component mixture pressure sensitive adhesives are preferably used due to their ease of handling and stable adhesive strength.

[0041] Among these, (meth)acrylic adhesives and silylated urethane resin adhesives can be suitably used from the viewpoints of transparency and excellent adhesiveness.

[0042] Additives such as a crosslinking agent, a tackifier, an ultraviolet absorber, and a light stabilizer can be added to the pressure-sensitive adhesive as required.

[0043] Examples of the crosslinking agent include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an amine-based crosslinking agent, etc. These may be used alone or in combination of two or more. A particularly preferred crosslinking agent is an isocyanate-based crosslinking agent, which is a structural unit of the polymer that constitutes the adhesive. The amount of the isocyanate crosslinking agent is 0.3 to 4 parts by mass, preferably 0.5 to 3 parts by mass, per 100 parts by mass of the monomer (e.g., the total of BA and AA). When the amount of the isocyanate crosslinking agent is 0.3 parts by mass or more, the cohesive force of the adhesive is improved, and the strength of the adhesive layer can be increased. When the amount of the isocyanate crosslinking agent is 4 parts by mass or less, the adhesive can have an appropriate flexibility.

[0044] The tackifier can be selected in consideration of the softening point, compatibility with each component, etc. Examples include terpene resin, rosin resin, hydrogenated rosin resin, coumarone-indene resin, styrene resin, aliphatic petroleum resin, alicyclic petroleum resin, terpene-phenol resin, xylene resin, other aliphatic hydrocarbon resin or aromatic hydrocarbon resin, etc. These may be used alone or in combination of two or more. The ultraviolet absorber and light stabilizer may be the above-mentioned ones.

[0045] Examples of adhesives include (meth)acrylic resin adhesives, natural rubber adhesives, urethane resin adhesives, ethylene-vinyl acetate resin emulsion adhesives, ethylene-vinyl acetate resin adhesives, epoxy resin adhesives, vinyl chloride resin solvent-based adhesives, chloroprene rubber adhesives, cyanoacrylate adhesives, silicone adhesives, styrene-butadiene rubber solvent-based adhesives, nitrile rubber adhesives, nitrocellulose adhesives, phenolic resin adhesives, modified silicone adhesives, polyester adhesives, polyamide adhesives, polyimide adhesives, olefin resin adhesives, vinyl acetate resin emulsion adhesives, polystyrene resin solvent-based adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone resin adhesives, polyvinyl butyral adhesives, polybenzimidazole adhesives, polymethacrylate resin solvent-based adhesives, melamine resin adhesives, urea resin adhesives, resorcinol adhesives, etc. The adhesives can be used alone or in combination of two or more.

[0046] Adhesives can be classified according to the type of adhesion, into hot melt adhesives, two-component curing adhesives, heat curing adhesives, UV curing adhesives, and the like. Among these, two-component curing adhesives, heat curing adhesives, and UV curing adhesives are preferably used due to their ease of handling and stable adhesive strength.

[0047] Among the above adhesives, cyanoacrylate-based curing adhesives are preferred because of their ease of handling and stable adhesive strength. In the adhesive, additives such as the above-mentioned crosslinking agents, tackifiers, ultraviolet absorbers, light stabilizers, etc. can be added as necessary. In addition, thixotropic agents, pigments, defoamers, diluents, curing speed regulators, etc. can also be added within the range that does not affect the performance.

[0048] <2. Manufacturing method of bolt, nut and cap> The bolt and nut cap according to the present embodiment is manufactured by injection molding. Injection molding is a molding method in which a resin such as a thermoplastic resin is heated and melted, then injected into a mold at high pressure, and cooled and solidified while maintaining the pressure, and any conventionally known injection molding method can be used. The thickness of the bolt and nut cap can be precisely controlled by the gap in the mold, and can be kept within the above-mentioned tolerance.

[0049] <3. Protection or repair method using bolt, nut and cap> The bolt and nut cap can protect or repair either or both of the bolt and nut by using a predetermined adhesive to cover the protruding parts of either or both of the bolt and nut and fixing it to a desired surface (generally the surface of the structure to which the bolt and nut are fixed) or to a corrosion-resistant sheet covering that surface. It is preferable that both the bolt and nut cap and the adhesive are transparent, since the deterioration state of the covered protruding parts (e.g., bolt and nut) can be visually confirmed. As the adhesive, the adhesives mentioned in the description of the adhesive layer above can be suitably used. A detailed description of the adhesive is omitted, as it has already been described.

[0050] The bolt nut cap according to the present embodiment can be used, for example, to protect one or both of the bolts and nuts constituting a newly constructed steel structure. By covering one or both of the bolts and nuts constituting a newly constructed steel structure with the bolt nut cap according to the present embodiment, it is possible to improve corrosion resistance and weather resistance. In addition, the bolt nut cap according to the present embodiment can be used to repair one or both of the bolts and nuts constituting an existing steel structure. By covering one or both of the bolts and nuts constituting an existing steel structure with the bolt nut cap according to the present embodiment, it is possible to delay the progress of deterioration of one or both of the bolts and nuts due to corrosion, rust, etc., from the current state.

[0051] Therefore, in another embodiment of the present invention, there is provided a method for protecting or repairing one or both of a bolt and a nut, which comprises using an adhesive to fix the bolt and nut cap according to the above embodiment so as to cover protruding portions of the bolt and / or the nut.

[0052] In another embodiment of the present invention, there is provided a method for protecting or repairing a steel structure comprising a steel material and bolts and nuts fixed to the steel material, the method comprising the steps of: using a planar corrosion-protecting sheet having an adhesive on one side, and placing and attaching the adhesive-bearing side of the planar corrosion-protecting sheet to the flat surface of the steel material excluding the bolts and nuts and the edges of the steel material; using a Z-shaped corrosion-protecting sheet (corner film) having an adhesive on the inner or outer surface of a Z-shaped cross-section, and placing and attaching the adhesive-bearing side of the Z-shaped corrosion-protecting sheet from below or above the planar corrosion-protecting sheet so as to follow the edges of the steel material; and using an adhesive to fix a bolt and nut cap according to the above embodiment onto the planar corrosion-protecting sheet so as to cover the protruding portions of one or both of the bolts and nuts.

[0053] 2 and 3, a nut (50B) is screwed onto a tip (50C) of a bolt inserted into a bolt hole (43) formed in a steel material (40) via a washer (50A). In addition, the nut and bolt protrusions (50) fixed to the steel material (40) and the bolt head (50D) are covered using bolt nut caps (1A, 1B) of types A and B. The inner surfaces of the flanges (14A, 14B) of the bolt nut caps (1A, 1B) can be bonded via a pressure-sensitive adhesive (6) to a planar corrosion protection sheet (2) attached to the surface (41) of the steel material.

[0054] Also, the inner surfaces of the flanges (14A, 14B) of the bolt and nut caps (1A, 1B) may be directly bonded to the surface (41) of the steel material. As shown in FIG. 2, by overlapping the flanges (14A, 14B) of the bolt and nut caps with the end of the planar corrosion protection sheet (2) (in this embodiment, the annular end formed along the outer periphery of the hole (43)), it is possible to configure so that there is no uncoated portion between the planar corrosion protection sheet (2) and the bolt and nut caps (1A, 1B). Alternatively, on the contrary, by fixing the bolt and nut caps (1A, 1B) to the surface (41) of the steel material, and then attaching the end of the planar corrosion protection sheet (2) to the flanges (14A, 14B) of the bolt and nut caps so as to overlap each other, it is possible to configure so that there is no uncoated portion between the planar corrosion protection sheet (2) and the bolt and nut caps (1A, 1B).

[0055] There are no particular limitations on the bolts and nuts to be covered with the bolt and nut caps, but examples of the bolts and nuts that can be used include high-strength bolts, high-strength hexagonal bolts, torsion-type high-strength bolts, hot-dip galvanized high-strength bolts, rust-proofed high-strength bolts, weather-resistant steel high-strength bolts, fire-resistant steel high-strength bolts, coastal weather-resistant steel high-strength bolts, and ultra-high-strength bolts. Examples of standards include JIS B1186:2013.

[0056] The structure of the bolt and nut cap can be modified as appropriate according to the shape of the bolt and nut. For example, Fig. 2 shows a schematic side cross-sectional view of the bolt and nut cap (1A, 1B) and the steel material (40) when the combination of a hexagonal bolt and a hexagonal nut fixed to the steel material is covered by the bolt and nut cap. In this embodiment, the hexagonal bolt and the hexagonal nut are both fixed to the steel material (40) with a washer (50A) sandwiched therebetween. Alternatively, the same bolt and nut cap (1A, 1B) can be used to cover a torsion-type high-strength bolt fixed to the steel material.

[0057] The surface of the steel material (40) does not have to be coated with paint, but is generally coated with paint, typically with an anti-rust paint. For this reason, the surface of the steel material is generally protected with a coating, typically with an anti-rust coating. Examples of anti-rust paint include, but are not limited to, fluororesin paint, polyurethane resin paint, and epoxy resin paint. These may be used alone, but are preferably used in combination to improve corrosion resistance. When painting, it is preferable to prepare the surface of the steel material in advance by blasting or the like in order to improve the adhesion of the paint.

[0058] In a preferred embodiment, the surface of the steel material constituting the steel structure can be coated with a heavy-duty anticorrosive coating consisting of four layers: anticorrosive base, undercoat layer, intermediate coat layer, and top coat layer. Examples of paints for anticorrosive base include inorganic zinc-rich paint and organic zinc-rich paint. Examples of paints forming the undercoat layer include epoxy resin paint. Examples of paints forming the intermediate coat layer include epoxy resin paint and fluororesin paint. Examples of paints forming the top coat layer include fluororesin paint and polyurethane resin paint. The paints forming each layer may be used alone or in combination. An example of a process for heavy-duty anticorrosive coating is the C-5 coating system described in the Steel Highway Bridge Coating and Anticorrosion Handbook (Japan Road Association).

[0059] There are no particular limitations on the steel structure, but examples include steel structures installed in an exposed outdoor state, such as bridges, water gates, steel towers, pipelines, marine structures, gas tanks, plants, wind power propeller towers, buildings, factories, warehouses, parking lots, fences, roofs (for example, structures supporting nets to prevent golf courses from flying into highways), and undulating gates. Steel structures installed in an exposed outdoor state are exposed to an environment that is prone to corrosion due to the adhesion of moisture and salt, so the effect of using the bolt and nut cap according to the present invention is remarkable. Fig. 3 is a perspective view showing an example in which this embodiment is applied to a part of a steel structure.

[0060] On the surface of the steel material that constitutes a steel structure, there are parts where it is easy to ensure the desired paint film thickness, and parts where it is difficult to ensure the desired paint film thickness. In steel structures, rust and corrosion often occur starting from the parts where it is difficult to ensure the paint film thickness. For this reason, in protecting or repairing steel structures, it is preferable to attach an anticorrosion sheet to such parts where it is difficult to ensure the paint film thickness. Even if an anticorrosion sheet is not attached to the entire surface of the steel material that constitutes the steel structure, if an anticorrosion sheet can be attached to the parts where it is difficult to ensure the paint film thickness, a high protection or repair effect can be obtained, which is economical.

[0061] Portions where it is difficult to ensure a coating thickness include, but are not limited to, component corners (edge ​​surfaces), welds, ridges, corners (vertices of polygons), etc. Note that component corners (edge ​​surfaces) refer to the exposed plate thickness surface of a plate-shaped portion when the steel material constituting a steel structure has such a plate-shaped portion. The length of the component corners (edge ​​surfaces) in the plate thickness direction is, but is not limited to, generally 1.6 to 100 mm, typically 9 to 50 mm.

[0062] When attaching the anticorrosive sheet to the corners (edges) of the steel material constituting the steel structure, it is possible to attach the anticorrosive sheet only to the corners (edges) of the material, but it is more preferable to use a corner film (3) that is attached to the corners (edges) (41A) of the material across at least a part of each of a pair of flat surfaces (41B, 41C) adjacent to the corners (edges) (41A) of the material, as shown in FIG. 2, in order to increase the durability of the steel structure. This configuration is efficient because the corner film (3) can be attached to the corners (edges) (41A) and ridges of the material at the same time. In the embodiment shown in FIG. 2, the flat surfaces (41B, 41C) of the steel surface (41) have uncoated parts that are not covered by the flat anticorrosive sheet (2) or the bolt and nut caps (1A, 1B), but since the uncoated parts are parts where the coating thickness can be easily ensured, there is no big problem even if they are not necessarily covered by these.

[0063] Examples of corrosion-resistant sheets include resin sheets, particularly fluororesin-based sheets, poly(meth)acrylic acid ester-based sheets, high-density polyethylene sheets, polypropylene sheets, polyvinyl chloride sheets, etc., but are not limited to these sheets, and any known corrosion-resistant sheet may be selected depending on the required characteristics.

[0064] A particularly suitable anticorrosion sheet is a fluorine-based resin containing one or both selected from the group consisting of polyvinylidene fluoride resin and ethylene-chlorotrifluoroethylene copolymer. An example of such an anticorrosion sheet is a laminated structure having a fat layer and an adhesive layer in this order from the outside to the inside. In particular, an anticorrosion sheet having a laminated structure having a plurality of fluororesin layers and adhesive layers in this order from the outside to the inside is preferred. The adhesive layer can suitably contain, for example, the adhesive described above. This anticorrosion sheet is used by attaching the adhesive layer to the surface of a steel material.

[0065] It is preferable that the surface to which the pressure-sensitive adhesive is applied has a thermoplastic resin layer. The anticorrosive sheet used in this embodiment has a transmittance of 10% or less in the ultraviolet wavelength range of 315 to 380 nm, a total light transmittance of 75% or more in the visible light range measured in accordance with the measurement method specified in JIS K7361-1-1997, and a thickness of 30 to 2000 μm. The reason for the limitation is the same as the composition of the bolt, nut, and cap. EXAMPLES

[0066] The present invention will be described in detail below based on examples and comparative examples. The bolt nut cap of type A had an opening inner diameter of 50 mm, a flange outer diameter of 70 mm, a height of 46 mm and a thickness of 1.5 mm. The bolt nut cap of type B had an opening inner diameter of 50 mm, a flange outer diameter of 70 mm, a height of 26 mm, a thickness of 1.5 mm and an inner curvature of the shoulder cross section of 9.5 mm. The thickness tolerance of the top and body of all bolt nut caps was within the range of -5% to +5%. The flat corrosion protection sheet and corner film had a PVDF layer, an acrylic resin layer and a silylated urethane resin adhesive layer in that order from the outer side. A cyanoacrylate curing adhesive was used as the adhesive.

[0067] (UV transparency) The same composition as that used for the bolt and nut caps was used to injection mold a 2 mm thick plate to obtain a plate sample. This composition sample was subjected to an ultraviolet irradiation test. The transmittance of ultraviolet light in the wavelength range of 315 to 380 nm was at most 7%. This material is suitable for long-term exposure because it reduces ultraviolet deterioration of the adhesive applied to the contact surface of the base material. The anticorrosion sheet was also subjected to a 300-hour ultraviolet irradiation test, and the transmittance was less than 10%.

[0068] (Visible light transparency) The total light transmittance of the above-mentioned flat plate sample in the visible light region was measured in accordance with JIS K7361-1-1997. The total light transmittance in the visible light region was 75% or more. The haze value according to JIS K7136-2000 was 2.5%.

[0069] (Weather resistance test) The above flat plate sample (invention example) was subjected to an exposure test using a xenon arc lamp in accordance with ISO4892-2 as an accelerated weathering test. The yellowing index after 2000 hours of accelerated weathering test was investigated. As comparative examples, the yellowing index after 2000 hours of accelerated weathering test was similarly investigated for commercially available bolt and nut cap materials A, B, and C, polycarbonate (PC), and acrylic resin (PMMA). The results are shown in Figure 4. The inventive example has a smaller yellowing index than the existing products (A, B, C) and polycarbonate, at approximately 1.0 or less, and can be said to have excellent weather resistance, similar to acrylic resin.

[0070] (strength) The above flat plate sample and a commercially available material were subjected to tensile strength tests before and after the same accelerated weathering test, and the results are shown in Figure 5. The vertical axis represents the tensile strength before the accelerated weathering test as 100%. The inventive example showed no decrease in strength even after 20,000 hours of accelerated weathering test. The comparative example began to decrease in strength within 1,000 hours, and at 2,000 hours it only maintained less than 80% of its pre-test strength. [Explanation of symbols]

[0071] 1 bolt nut cap 1A (Type A) Bolt Nut Cap 1B (Type B) Bolt Nut Cap 11A, 11B Heaven 12B Shoulder 13A, 13B Torso 14A, 14B flange section 15A, 15B opening 2 (Anti-corrosion sheet) (flat film) Flat anti-corrosion sheet 3 (Corrosion prevention sheet) (Corner film) Z-shaped corrosion prevention sheet 40 Steel material 41 Steel Surface 41A Corner of component (edge ​​surface) 41B, 41C flat part 43 Bolt Hole 50 Nut and bolt protrusions 50A washer 50B Nut 50C Bolt tip 50D Bolt Head 6 Adhesive

Claims

1. A bolt and nut cap formed by injection molding a composition containing at least one thermoplastic resin selected from the group consisting of polyimide resin, polyacrylic ester resin, polyvinyl chloride resin, polycarbonate resin, polyethylene terephthalate resin, polyamide resin, and acrylonitrile-butadiene-styrene copolymer, The transmittance in the ultraviolet wavelength range of 315 to 380 nm is 10% or less, A bolt / nut cap having a yellowing index of 2.0 or less after an accelerated weather resistance test in which an exposure test using a xenon arc lamp is performed for 2000 hours in accordance with ISO 4892-2.

2. The container has a hemispherical or disc-shaped top portion, a cylindrical body portion whose entire circumference is connected to one end of the top portion without any corners, and an annular flange portion whose entire circumference is connected to the other end of the body portion, 2. The bolt nut cap according to claim 1, wherein the thickness tolerance of the top portion and the body portion is in the range of −15% to +15%.

3. The bolt nut cap according to claim 1, having a total light transmittance of 75% or more in the visible light range measured in accordance with the measurement method specified in JIS K7361-1-1997.

4. The bolt nut cap according to claim 1, wherein the tensile strength after an accelerated weathering test in which an exposure test for 2000 hours is performed using a xenon arc lamp in accordance with ISO 4892-2 is 80% or more of the tensile strength before the test.

5. A method for protecting or repairing one or both of a bolt and a nut, comprising fixing the bolt nut cap according to any one of claims 1 to 4 to cover the protruding portions of one or both of the bolt and the nut using an adhesive.

6. A method for protecting or repairing a steel structure having a steel material and a bolt and a nut fixed to the steel material, comprising the steps of: A step of attaching a flat corrosion protection sheet having an adhesive on one side to a flat surface of the steel material excluding the bolts and nuts and the edge of the steel material, with the adhesive side of the flat corrosion protection sheet being placed on the flat surface of the steel material; A process of using a Z-shaped corrosion protection sheet having an adhesive on the inner or outer surface of the Z-shaped cross section, and attaching the adhesive-bearing surface of the Z-shaped corrosion protection sheet to the bottom or top of the planar corrosion protection sheet so as to follow the edge of the steel material; A step of fixing the bolt nut cap according to any one of claims 1 to 4 on the planar corrosion-protecting sheet using a pressure-sensitive adhesive so as to cover one or both of the protruding portions of the bolt and the nut; A method for protecting or repairing a steel structure, comprising:

7. The planar corrosion protection sheet and the Z-shaped corrosion protection sheet are The adhesive has a fluororesin layer on the outer surface side and a thermoplastic resin layer on the surface to which the adhesive is applied, The transmittance in the ultraviolet wavelength range of 315 to 380 nm is 10% or less, The total light transmittance of the visible light wavelengths measured in accordance with the measurement method specified in JIS K7361-1-1997 is 75% or more, The method for protecting or repairing a steel structure according to claim 6, wherein the thickness is in the range of 30 to 2000 μm.

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