Composition for adhering iron or iron alloy and adhesion method

Abstract

To provide an adhesive for steel structures that achieves both adhesion strength and rust prevention capability.SOLUTION: A first member composed of iron or an iron alloy is adhered to a second member by means of a composition containing an adhesive resin and a solid-phase powder including a sacrificial metal material containing one or more metals selected from the group consisting of magnesium, zinc, and aluminum, and an abrasive, the sacrificial metal material in the solid-phase powder being mixed into the adhesive resin so as to be greater than 50 mass% and less than 100 mass%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The following disclosure relates to a composition for adhesion and a bonding method using said composition, and in particular to a composition and bonding method that exhibit not only adhesive strength but also corrosion resistance when used in the assembly of steel structures. [Background technology]

[0002] Conventionally, steel structures have been assembled by joining components together by riveting, bolting, or welding. All of these methods require a great deal of labor, and riveting and welding require special skills. Furthermore, special considerations regarding safety management are required because high temperatures are involved. In light of these problems, and primarily from the perspective of labor saving, the use of adhesives to bond components together has been studied as a supplement to or alternative to bolting. Patent Document 1 discloses related technology.

[0003] Many steel structures are used outdoors. When exposed to rainwater, they are prone to rusting relatively quickly, and even if not, they are prone to microscopic or macroscopic condensation caused by temperature differences between day and night. If rust occurs in adhesive joints, the expansion force can reduce adhesive strength, or it can cause bolts to loosen or deformation near the adhesive joints. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2011-176944 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, steel structures are painted to prevent rust, but painting the bonding surface before bonding significantly reduces the adhesive strength, and the bonding surface cannot be painted after the components have been joined. How to prevent rust on the bonding surface is an important technical factor in the adhesion of steel structures. [Means for solving the problem]

[0006] The composition of the present disclosure that can be used for bonding iron or iron alloys includes an adhesive resin, a solid-phase powder containing a sacrificial metal material containing one or more metals selected from the group consisting of magnesium, zinc, and aluminum, and an abrasive, wherein the sacrificial metal material is mixed with the adhesive resin in an amount greater than 50% by mass and less than 100% by mass.

[0007] Preferably, the abrasive is one or more selected from the group consisting of alumina, silicon carbide, cubic boron nitride, garnet, and diamond. Also preferably, the sacrificial metal material is made of zinc or a zinc alloy. Alternatively, preferably, the sacrificial metal material is a powder having an average particle size of 10 nm or more and 1 mm or less, and the abrasive is a powder having an average particle size of 10 μm or more and 1 mm or less. Also, a structure according to the present disclosure includes a first member made of iron or an iron alloy, a second member in contact with the first member, and the composition interposed at the interface between the first member and the second member and hardened.

[0008] Furthermore, the method of adhering a first member made of iron or an iron alloy to a second member according to the present disclosure comprises preparing a composition by mixing a solid-phase powder containing a powder of a sacrificial metal material and a powder of an abrasive material with an adhesive resin so that the sacrificial metal material accounts for more than 50% by mass but less than 100% by mass of the solid-phase powder; interposing the composition at the interface between the first member and the second member; pressing and rubbing the second member against the first member; and hardening the composition at the interface. [Effects of the Invention]

[0009] An adhesive for steel structures is provided that has adhesive strength and rust prevention properties. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 1 is a cross-sectional view that schematically shows the vicinity of an adhesive interface in a steel structure bonded with a composition according to one embodiment. [Figure 2] FIG. 2 is a graph showing the effect of the zinc ratio in the solid phase powder on the potential of the composition. [Figure 3] Figure 3 is a photograph of the appearance after peeling based on an adhesion evaluation test. [Figure 4] Figure 4 shows the appearance of the test piece for the corrosion test and after the test. DETAILED DESCRIPTION OF THE INVENTION

[0011] Some exemplary embodiments are described below with reference to the accompanying drawings.

[0012] Referring to FIG. 1 , the composition 1 according to this embodiment can be suitably used to form a structure 7 by bonding together components 3 and 5, at least one of which is made of iron or an iron alloy. Neither component 3 nor component 5 needs to be made of iron or an iron alloy. However, if either component is made of iron or an iron alloy, the composition 1 will provide sacrificial corrosion protection to protect the components 3 and 5. Of course, both components 3 and 5 may be made of iron or an iron alloy. One of components 3 and 5 may be a relatively small structure such as a nameplate or decorative item, or a non-structural object such as a film or cover. Needless to say, bonding can be combined with other fastening methods, such as bolt fastening, or the composition 1 can also be used to bond the bearing surfaces of bolts. Alternatively, instead of being used for bonding, the composition 1 could be used as a paint or a paint primer.

[0013] Composition 1 is composed of adhesive resin 9 and solid powder 11 mixed or suspended in resin 9, and is present at the interface where members 3 and 5 come into contact, and when hardened, it bonds members 3 and 5 together. Needless to say, composition 1 is preferably densely filled at the interface, but air bubbles or cavities may inevitably be contained.

[0014] Any resin having adhesive properties can be used for the resin 9. For example, epoxy resin is suitable because of its excellent adhesive strength to metals. To improve the peel resistance, impact resistance, or other properties of the epoxy resin, polymers such as nylon, isocyanate, or appropriate elastomers may be added to the resin 9. In practice, one-component resins that do not require a curing agent are used, but two-component resins may also be used.

[0015] Of course, other polymers such as acrylic resins, urethane resins, phenolic resins, cyanoacrylates, polyimides, silicones, styrene-butadiene rubbers, and nitrile rubbers can be used instead of or in addition to epoxy resins, depending on the environment in which Composition 1 will be placed or the desired properties. Alternatively, other adhesive substances such as cement and ceramics, which cannot be considered resins, can also be used.

[0016] The solid phase powder 11 generally comprises a sacrificial metal material 13 and an abrasive material 15 .

[0017] The sacrificial metal material 13 is made of a metal having an electrochemically lower potential than iron, and thus sacrificially dissolves to supply a corrosion protection current to the iron. A typical example is zinc, but magnesium, aluminum, or alloys of these can also be used. The sacrificial metal material 13 is a powder separate from the abrasive 15, although this is not essential. Its particle size is not particularly limited, but is preferably 10 nm or larger for ease of handling and 1 mm or smaller for ease of mixing with the resin 9.

[0018] The abrasive 15 is a hard particle with a hardness greater than that of iron, which, when pressed against the iron, scrapes it to create a rough surface. The rough surface not only increases the adhesive strength of the composition 1 but also promotes electrical contact between the sacrificial metal material 13 and the members 3 and 5, thereby enhancing its sacrificial anticorrosion effect. A typical example of hard particles is alumina powder, but particles of silicon carbide, cubic boron nitride, garnet, diamond, etc., or mixtures thereof can also be used. The particle size is not particularly limited, but is preferably 10 μm or more in order to impart sufficient roughness to the members 3 and 5, and preferably 1 mm or less in order to facilitate mixing with the resin 9.

[0019] Regarding the mixing of the solid-phase powder 11 with the resin 9, from the viewpoint of obtaining sufficient sacrificial anticorrosion ability and polishing ability, it is preferable that the resin 9 is 80 mass % or less and the solid-phase powder 11 is 20 mass % or more. On the other hand, if the amount of resin 9 is too small, there is a concern that the adhesive strength will decrease, so it is preferable that the resin 9 is 30 mass % or more and the solid-phase powder 11 is 70 mass % or less.

[0020] The mixing ratio of the sacrificial metal material 13 and the abrasive 15 in the solid-phase powder 11 is preferably specified within a certain range. That is, to ensure sufficient sacrificial corrosion protection, the sacrificial metal material 13 preferably exceeds 50 mass% in the solid-phase powder 11. On the other hand, as will be described in detail later with reference to test results, contrary to the expectation that a larger amount of the sacrificial metal material 13 would enhance sacrificial corrosion protection, the sacrificial metal material 13 is preferably less than 100 mass%, i.e., the abrasive 15 is essentially included. The reason for this is not entirely clear, but it is likely that when only the sacrificial metal material 13 is included, electrical contact with the members 3 and 5 is insufficient, and one or more of the following factors are responsible: a wide contact surface brought about by the roughened surface due to the abrasive 15, exposure of an electrically active surface, or the effect of the abrasive 15 causing the sacrificial metal material 13 to bite into the members 3 and 5. That is, preferably, the abrasive 15 exceeds 0 mass% in the solid-phase powder 11, and the sacrificial metal material 13 is less than 100 mass%.

[0021] Furthermore, composition 1 may contain other solid phases in addition to sacrificial metal material 13 and abrasive 15. For example, iron powder may be included as cuttings when abrasive 15 cuts members 3 and 5, or unintended foreign powder may be included during construction. Furthermore, solid phases such as aggregates and ceramic fibers may be intentionally added to composition 1 for the purpose of increasing its strength.

[0022] The bonding of the members 3 and 5 using the composition 1 generally involves preparing the composition 1 as described above, placing the composition 1 at the interface between the first member 3 and the second member 5, and, for example, pressing and rubbing the second member 5 against the first member 3 to form a rough surface on the members 3 and 5, and leaving them for a certain period of time and / or heating the members 3 and 5 to cure the composition 1. More details are as follows.

[0023] Needless to say, composition 1 is prepared before resin 9 is cured, i.e., while resin 9 is in a liquid or colloidal state. Resin 9 may be fluidized by dissolving a polymer in any solvent, including water, or resin 9 may be a substrate in a monomer or oligomer state prior to polymerization. As already mentioned, it may be a one-component type or a two-component type consisting of a combination of a base resin and a curing agent.

[0024] The solid-phase powder 11 is mixed into the resin 9 in this state, or into either its base or curing agent. The mixing may be done in advance or on-site just before bonding. The sacrificial metal material 13 and the abrasive 15 may be mixed separately, or they may be mixed in advance to a desired mixing ratio and then the mixture may be mixed into the resin 9. In either case, the solid-phase powder 11 is mixed with the resin 9 so that the sacrificial metal material 13 is more than 50 mass % but less than 100 mass % in the solid-phase powder 11, to prepare the composition 1.

[0025] Composition 1 is applied, for example, to the bonding surface of the first member 3. Alternatively, or in addition, composition 1 may also be applied to the bonding surface of the second member 5. An appropriate jig can be used for application. After application, the members 3 and 5 are bonded together, so that composition 1 is interposed at their interface. Alternatively, the bonding surfaces of the members 3 and 5 may be brought into contact with each other, and composition 1 may be pressed into the interface.

[0026] In either case, with the composition 1 interposed at the interface between the first member 3 and the second member 5, the second member 5 is pressed against the first member 3 (or vice versa, or both members are pressed against each other). The pressing force is, for example, but not limited to, a pressure of about 1 Pa to 1 kPa at the bonding surface. Furthermore, while pressed, the members 3 and 5 are shifted relative to each other parallel to the interface, thereby rubbing the second member 5 against the first member 3, thereby forming a rough surface on the bonding surface with the abrasive 15. The rubbing may be a linear movement in one direction, a bidirectional movement, or a circular or other two-dimensional movement. Furthermore, the rubbing may be performed not only once, but as many times as possible. More frequent rubbing contributes to improved adhesive strength and promotes electrical contact of the sacrificial metal material 13 with the members 3 and 5. In addition to or instead of rubbing the members 3 and 5 together, the composition 1 may be rubbed onto the members 3 and 5 while pressing them together using a suitable jig, and then the members 3 and 5 may be brought into close contact with each other.

[0027] The composition 1 is then cured to bond the members 3 and 5 together. Curing occurs by leaving the composition 1 for a certain period of time or by additionally heating the area near the bond, depending on the type of resin 9. If necessary, bolts are further tightened before or after curing to join the members 3 and 5 together and assemble the structure 7.

[0028] The above-described method eliminates the need for surface preparation, such as blasting, before bonding, or reduces the effort required, allowing for more efficient construction. While scraping the bonding surface generates chips that become entrained in the adhesive resin, the amount is minimal compared to the chip particles generated by blasting, and therefore the adverse effect on adhesive strength is negligible. In fact, the process of pressing and rubbing the components together facilitates the removal of air bubbles within the composition 1, and the rough surface naturally provides an anchoring effect, improving adhesive strength. Furthermore, after bonding, the sacrificial metal material 13 electrically connected to the components 3 and 5 supplies a sacrificial anticorrosion current to the components 3 and 5, making the bonding surface less susceptible to rust and maintaining long-term adhesive strength.

[0029] In order to confirm the effects of this embodiment, the following tests were carried out.

[0030] To 50 g (or 40 g) of epoxy resin grease-like adhesive available under the name Alpron (registered trademark of Nippon America Resin Co., Ltd.), 50 g (or 60 g) of #220 alumina particles and zinc powder were added to achieve the composition shown in Table 1, and the mixture was stirred with a stirrer until homogeneous (samples a to f). An appropriate amount of each was applied to SPCC (JIS G3141) cold-rolled steel sheets (150 mm x 70 mm x 1.3 mm). The applied compositions were then rubbed onto the steel sheets using a 20 mm φ probe for adhesion testing (see "Steel Structure Coating Film Inspection Manual," revised February 1, 2018, p. 58, edited by the Japan Steel Construction Institute). After curing, the potential was measured by pressing a saturated calomel electrode with absorbent cotton soaked in saturated sodium sulfate solution against each sample. After allowing sufficient time for the potential to stabilize, the values ​​are listed in the rightmost column of Table 1. It goes without saying that the compositions listed in Table 1 are shown in terms of mass ratios before curing, and it should be noted that the compositions after curing, particularly the mass ratios of the resins, will differ from those in the table due to the evaporation of volatile components, etc.

[0031] [Table 1]

[0032] Figure 2 plots the potential versus the zinc ratio in the solid-phase powder for these samples with the same solid-phase powder content. For sample a, which contained 50% by mass of zinc as a sacrificial metal in the solid-phase powder, the potential was measured at -450 mV (SCE). The potential, which is more noble than that of iron, is presumably due to overpotential caused by the resin, but in any case, this is not a potential at which sufficient sacrificial protection can be expected. On the other hand, for samples b and c, which contained 100% by mass of zinc, the potentials were -530 mV and -490 mV (SCE), respectively, which, contrary to expectations, are not sufficient sacrificial protection. In comparison, samples d and e, which contained alumina particles as abrasives, exhibited potentials of -859 and -792 mV (SCE), respectively, indicating that they are expected to exhibit sacrificial protection against iron or iron alloy components.

[0033] In other words, contrary to the expectation that the more sacrificial metal material is added, the higher the sacrificial corrosion protection performance can be expected. However, it is understood that replacing part of the sacrificial metal material with abrasives can actually expect a higher sacrificial corrosion protection performance. From the standpoint of sacrificial corrosion protection performance, these test results show that the amount of abrasive added to the solid-phase powder should exceed 0% by mass, and conversely, the amount of sacrificial metal material should be less than 100% by mass. On the other hand, a comparison of sample a with samples d and e shows that the amount of sacrificial metal material should exceed 50% by mass.

[0034] Next, the adhesive strength of the composition was tested. Compositions corresponding to samples d through g listed in Table 1 were prepared and applied to pre-blasted SS400 (JIS G3101) steel (150mm x 70mm x 3.2mm), and an adhesion test was performed using the above-mentioned φ20mm terminal. Figure 3 shows the results of the adhesive strength measurement, along with photographs of the composition side and the terminal side after peeling.

[0035] Sample g, which is entirely composed of epoxy resin, had an adhesive strength of 3.76 MPa, while sample f, which contained 50% by mass of alumina particles, had an adhesive strength of 4.27 MPa. This improvement in adhesive strength is attributed to the roughened surface caused by the abrasive. Furthermore, samples d and e, which contain zinc, had adhesive strengths of 4.60 MPa and 4.17 MPa, respectively. These were confirmed to be comparable to that of sample f. These test results indicate that an abrasive should be included in the composition, and that the inclusion of zinc along with the abrasive does not affect adhesive strength.

[0036] Next, a corrosion test was conducted. Compositions corresponding to samples e and g listed in Table 1 were prepared and applied to test pieces 19, each consisting of SPCC-SB (JIS G3141) cold-rolled steel sheet (150 mm × 70 mm × 1.2 mm), as shown in Figure 4(a). The 20 mm diameter terminal described above was used to rub the coating onto approximately half of the surface of each piece (composition 21). A scratch 23 (approximately 100 μm wide) was then created with a cutter, reaching down to the test piece 19, to produce test pieces 17. Each test piece 17 was subjected to a six-cycle (48-hour) combined cycle test (JASO M609). The appearances after the test are shown in Figures 4(b) and (c), respectively.

[0037] For sample g (FIG. 4(c)), which does not contain zinc, red rust was observed on the surface where composition 21 was not applied, as well as on the periphery of the surface where composition 21 was applied and in the vicinity of scratch 23. For sample e (FIG. 4(b)), which contains zinc, red rust was observed on the surface where composition 21 was not applied and in scratch 23, but no red rust was observed on the surface where composition 21 was applied. It can be confirmed that the composition according to this embodiment effectively exerts sacrificial corrosion protection properties on steel sheets.

[0038] Although several embodiments have been described, modifications or variations of the embodiments can be made based on the above disclosure. [Industrial Applicability]

[0039] The adhesive for steel structures that has adhesive strength and rust prevention properties is provided, contributing to the development of sustainable and resilient infrastructure, one of the Sustainable Development Goals (SDGs). [Explanation of symbols]

[0040] 1 composition 3,5 Components 7 Structures 9 Adhesive resin 11 Solid phase powder 13 Sacrificial metal materials 15 Abrasive material 17 Test pieces 19 Test material 21 Composition 23 Scratch

Claims

1. A composition that can be used to bond iron or iron alloys, comprising: an adhesive resin; A solid-phase powder containing a sacrificial metal material containing one or more metals selected from the group consisting of magnesium, zinc, and aluminum, and an abrasive, wherein the sacrificial metal material is mixed with the adhesive resin so that the content of the sacrificial metal material in the solid-phase powder is more than 50 mass% and less than 100 mass%; A composition comprising:

2. 10. The composition of claim 1, wherein the abrasive is one or more selected from the group consisting of alumina, silicon carbide, cubic boron nitride, garnet, and diamond.

3. The composition of claim 1 , wherein the sacrificial metal material comprises zinc or a zinc alloy.

4. 2. The composition according to claim 1, wherein the sacrificial metal material is a powder having an average particle size of 10 nm to 1 mm, and the abrasive material is a powder having an average particle size of 10 μm to 1 mm.

5. a first member made of iron or an iron alloy; a second member in contact with the first member; the composition of claim 1 interposed at the interface between the first member and the second member and cured; A structure equipped with:

6. 1. A method for bonding a first member made of iron or an iron alloy to a second member, comprising: A solid-phase powder containing a powder of a sacrificial metal material and a powder of an abrasive material is mixed with an adhesive resin so that the sacrificial metal material accounts for more than 50 mass % and less than 100 mass % of the solid-phase powder, to prepare a composition; the composition is placed at the interface between the first member and the second member, and the second member is pressed against and rubbed against the first member; curing the composition present at the interface; The method includes:

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