JP5100255B2 - Stainless steel plate / adhesive structure between objects and disassembly method thereof - Google Patents

Description

  The present invention is a stainless steel plate / object bonding structure formed by bonding a stainless steel plate to a certain object using a rubber-based adhesive, and has a high shear bonding strength and can be easily disassembled. The present invention relates to a structure and a disassembly method thereof.

  Stainless steel sheets are used in a wide range of fields such as kitchen appliances, home appliances, interior materials, exterior materials, utilizing their excellent corrosion resistance, cleanliness, and design, and bonded to the same or different materials with adhesives. Often used in the state. Among adhesives, rubber-based adhesives have a hardened adhesive layer (hereinafter simply referred to as “adhesive layer”) exhibiting rubber elasticity, not only joining stainless steel but also different types such as stainless steel and glass, stainless steel and plastic. The excellent flexibility is utilized in the joining of materials. For example, when one is a brittle material such as glass, or when there is a difference in thermal expansion characteristics between the two, it is very advantageous for reducing the damage caused by the brittle material and thermal expansion. In particular, silicone rubber-based adhesives are widely used in various applications in recent years because an adhesive layer that exhibits excellent heat resistance and electrical insulation and exhibits flexibility in a wide temperature range can be obtained.

  Thus, there are many merits in joining with a rubber adhesive. However, once joined, it is generally difficult to peel and disassemble the joint. One of the factors is that the adhesive layer exhibits rubber elasticity. That is, when an external force is applied to one end of the material on both sides sandwiching the adhesive layer, the adhesive layer elastically deforms to follow the displacement of the material on both sides, and the applied external force is applied to the wide adhesive layer. Since it is received by the area, a very large external force is required to peel off the materials to be bonded. For this reason, it is not easy to disassemble the joint.

  In recent years, the “dismantling property” of the bonded portion by the adhesive is often a problem from the viewpoint of recycling. Regarding a member obtained by joining a stainless steel plate with an adhesive, it is desired from the viewpoint of effective use of resources that expensive stainless steel is removed when discarded and separated and recycled from other materials. Also, in the field of material processing, non-magnetic materials may be temporarily fixed to the material surface with an adhesive, and even when applying non-magnetic austenitic stainless steel sheets for such applications, excellent dismantling properties are required. .

  Various proposals have been made for such a problem of “disassembly”. Typical adhesive disassembly techniques include a method of mixing thermally expandable microcapsules in an adhesive, a method of using a thermally decomposable polymer as an adhesive, and an aluminum foil sandwiched between a film-like hot melt adhesive tape. An all-over method is known in which an adhesive is softened, melted and peeled off by electromagnetic induction heating at the time of disassembly (Non-Patent Document 2, Patent Documents 2 and 3). In addition, as a method for separating the rubber-based material and the metal, a method using a pyrrolidone solvent as a solvent under pressure and heating conditions has been proposed (Patent Document 4).

  In addition to the problem of “dismantling”, there is a problem of “adhesion durability” in the case of joining stainless steel plates using an adhesive, in which the adhesive strength decreases due to use in a wet environment. This phenomenon of decreased adhesive strength is attributed to the passive film on the surface of the stainless steel plate. That is, the surface of the stainless steel plate is covered with a passive film composed mainly of chromium-iron-based oxides and hydroxides. It is believed that water molecules permeate into the interface of the adhesive layer and the chemical bond between the adhesive and the stainless steel surface is easily broken, so that the adhesive force is reduced in a short time. This phenomenon appears more prominently in a high temperature environment.

  As a method for improving “adhesion durability” in a wet environment, a method in which an organic primer such as an epoxy resin, an organic phosphoric acid compound, or polyacrylic acid is previously applied to the surface of a stainless steel plate is known (non- Patent Document 1). Primers dedicated to silicone rubber adhesives (sealing materials) are also commercially available from various manufacturers. In addition, the present inventors have formed a chemical conversion treatment film using a zirconium-based inorganic primer that does not contain organic components or harmful chromate compounds, so that the adhesive durability is maintained not only in a wet environment but also in a heat-resistant environment. A method for improving the performance was proposed (Patent Document 1).

  On the other hand, as a technique for roughening the surface of a stainless steel plate, a method for forming an electrolytically roughened surface that exhibits an excellent anchor effect on a coating film or the like is known (Patent Documents 5 to 7). This is to form pits with high density on the surface of the stainless steel plate by alternating electrolysis in a ferric chloride aqueous solution.

JP 2007-46097 A JP 2004-123943 A JP 2006-111716 A JP 2002-309033 A Japanese Patent No. 3664537 Japanese Patent No. 3664538 Japanese Patent No. 3818723 Shinichi Yanagihara, “2.1 Metal Adhesion and Primer”, Adhesion Technology, Japan Adhesive Society, Vol. 24, No. 3, (2004), Volume 76, p. 6-13 Chiaki Sato, “1.6 Dismantling Adhesive Technology, Recent Trends”, Adhesion Technology, Japan Adhesive Society, Vol. 25, No. 3, (2005), Volume 80, p. 25-29

  In order to give “decomposability” to the bonded portion, the method of mixing thermally expandable microcapsules into the adhesive or the above-described method employing a thermally decomposable polymer adhesive, the adhesive portion is 150 to 200 ° C. during disassembly. Need to be heated. For this reason, heat treatment equipment is required for the dismantling process, and it takes time and effort, and it is difficult to dismantle easily at low cost. Moreover, since it is assumed that peeling occurs during use in kitchen appliances due to heat generated by cooking, these methods are difficult to adopt.

In the all-over method, aluminum foil is used, so that it is difficult to apply to applications that require corrosion resistance such as around the water. Further, since a thermoplastic adhesive such as a hot-melt epoxy adhesive is used as the adhesive, it cannot be applied to applications requiring strength, elasticity, and sealing properties such as a silicone rubber adhesive.
The method of pressurizing and heating in a pyrrolidone solvent is not simple and difficult to spread widely as an actual work at a dismantling site.

  Further, in order to impart “adhesion durability” in the adhesion of the stainless steel plate, the above-described preliminary treatment in which a primer is previously applied to the stainless steel plate is effective. However, such a pretreatment alone cannot improve the “disassembly”.

In a joining method for bonding objects using an adhesive, a technique for easily disassembling a joint without heating has not been established at present.
In view of such a current situation, the present invention can be easily applied by applying a mechanical external force in spite of being able to impart a high shear bond strength to the joint, particularly in the joining of a stainless steel plate and an object with an adhesive. It is an object of the present invention to provide a joining technique capable of disassembling the joint, and at the same time to improve the adhesion durability in a wet environment which is a problem in the adhesion of stainless steel. Moreover, it aims at providing the dismantling method.

  The object is to provide a roughened surface A formed on the surface of a stainless steel plate having a thickness of 1.2 mm or less and satisfying the following condition (X) or (Y), the surface B of the object, and the AB. A stainless steel plate / object bonding structure having excellent dismantling properties, wherein the rubber adhesive layer C is embedded in the pits of the roughened surface A and adheres to the stainless steel plate.

(X): The pits are formed with a high density so that the area ratio of the pit non-occurrence portion is 30% or less, and the pit opening average diameter D (μm) and pit average depth H (μm) are the following (1) Electrolytic roughened surface satisfying the equation (2) and having an edge-like boundary between adjacent pits 2 ≦ D ≦ 10 (1)
0.3D ≦ H (2)
It is more preferable to adopt the following formula (2.1) instead of the above formula (2).
0.5D <H (2.1)

(Y); the average length RSm (μm) and arithmetic average roughness Ra of the contour curve element defined in JIS B0601 (2001) in the roughness curve of the surface A when the area ratio of the pit non-occurrence portion is 30% or less (Μm) satisfies the relationship of the following formulas (3) and (4), and has an electrolytic roughened surface having edge-like boundaries between adjacent pits 2 ≦ RSm ≦ 10 (3)
0.1RSm ≦ Ra (4)
It is more preferable to adopt the following formula (4.1) instead of the above formula (4).
0.2RSm ≦ Ra (4.1)

  “Thickness” is an average thickness obtained when the thickness of a stainless steel plate having a roughened surface is measured with a flat micrometer. The “object” having the surface B may be the same or different type of stainless steel plate, and plastics, glass, metal, wood and other various organic materials having a surface that can be joined to the stainless steel plate with a rubber adhesive. Alternatively, a plate-like or bulk-like one made of an inorganic substance is applicable. The “pits” on the surface A are pitting corrosion-like recesses formed on the surface of the stainless steel plate by electrolytic surface roughening. The “pit non-occurrence portion” is a portion where the original steel sheet surface remains. The “area ratio of the pit non-occurrence portion” is a pit non-occurrence portion (the original steel plate surface remains in the projected area of the observation field in the observation image of the roughened surface as illustrated in FIG. 1 described later. Part) of the projected area. A more suitable target is one in which the area ratio of the pit non-occurrence portion is 0% (a state where pits are formed on the entire surface as in the example of FIG. 1). The “edge-like boundary” is a sharp ridge-like portion formed by the contact between the wall surfaces of adjacent pits in the process of forming pitting corrosion-like pits by electrolytic etching.

The pit opening average diameter D (μm) is a cross section of a stainless steel plate having a roughened surface A cut along a plane including the thickness direction (hereinafter referred to as “cross section” unless otherwise specified). Is an average of values of the opening diameters D _k (k = 1, 2,..., N) of the pits appearing in FIG. The average pit depth H (μm) is an average value of the depths H _k (k = 1, 2,..., N) of each pit appearing in the same cross section. Specifically, in the observation image of the roughened surface as shown in FIG. 1, a cross section is assumed in which a straight line is drawn at random and cut along a plane parallel to the thickness direction including the straight line. At that time, the total number n of pits appearing in the cross section is set to 50 or more. When the total number n of pits cannot be secured in one section, 50 or more pits are assumed to be measured assuming a plurality of sections. FIG. 14 schematically shows a cross-sectional shape of a stainless steel plate having a roughened surface A. On the surface A of the stainless steel plate 10, there are pits 12 and edge boundaries 13, and in some cases, pit non-generated portions 14 exist. The opening diameter D _k of a certain pit 12 appearing in the cross section is the projected distance between the edge-like boundary 13 or the pit non-occurring part / pit boundary 15 located at both ends of the pit 12 (distance when viewed in the thickness direction). ). Also, the depth H _k of a certain pit 12 appearing in the cross section is based on the edge-like boundary 13 or the pit non-occurring part / pit boundary 15 located at both ends of the pit that is not low in height. Defined as the depth. These measurements can be performed by an observation technique such as a laser microscope capable of measuring in the depth direction. The average diameter D of pit openings is calculated by averaging n measured values of D _k (n ≧ 50), and the average pit depth is calculated by averaging n measured values of H _k (n ≧ 50). H is calculated.

  Moreover, when the roughened surface A is prescribed | regulated by a roughness curve like said (Y), the roughness curve can be measured with a laser microscope. The average length RSm (μm) and arithmetic average roughness Ra (μm) of the contour curve element defined in JIS B0601 (2001) are obtained from the measured roughness curve, and applied to the equations (3) and (4). To do.

  “Rubber adhesive” is an adhesive that exhibits the properties of an elastic body after curing, and specifically, an organic adhesive classified as a synthetic elastomer (elastic body) system (for example, a silicone rubber system, Modified silicone rubber, chloroprene rubber, nitrile rubber, styrene butadiene rubber, polysulfide, butyl rubber, acrylic rubber, urethane rubber, and the like) and natural natural rubber.

Moreover, in the present invention, as a technique for easily dismantling the above-mentioned adhesion structure,
In the adhesion structure, the area where the surfaces A and B are connected via the adhesive layer C is “adhesion area”, the end of the adhesion area is “adhesion end”, and the average of the adhesive layer C that is not elastically deformed When the thickness (that is, the average distance between the initial ABs) is referred to as “δ” and the thickness direction of the adhesive layer C is referred to as “δ direction”,
By applying an external force having a stress component in the δ direction to the bonded end of the stainless steel plate having the surface A to cause the stainless steel plate to bend and deform in the vicinity of the bonded end, the bonded end where the distance between AB is larger than δ, Breaking and separating the adhesive layer C into a portion remaining in the pits on the surface A and a portion adhering to the surface B of the object;
Thereafter, the external force having a stress component in the δ direction is continuously applied to the stainless steel plate in the region where the adhesive layer C is broken and separated, and the region where the distance between AB becomes larger than δ due to the flexural deformation is expanded. There is provided a method for disassembling a stainless steel plate / object bonding structure in which the layer C is successively broken and separated into a portion remaining in the pit of the surface A and a portion adhering to the surface B of the object.

The present invention has the following advantages.
(1) The “peeling adhesion strength” between the rubber adhesive layer having elasticity and the surface of the stainless steel plate is greatly reduced by the specific roughening form on the surface of the stainless steel plate. For this reason, it is extremely easy to peel and disassemble the stainless steel plate joined to the object surface using a rubber adhesive.
(2) Although the “peeling adhesive strength” is small, the initial “shearing adhesive strength” between the adhesive layer and the stainless steel plate is inferior to that of a general stainless steel plate not subjected to roughening treatment. High enough that there is no. Therefore, in a general application using the “shear adhesive strength”, an excellent adhesive force equivalent to that of the conventional one can be enjoyed.
(3) The “shear adhesive strength” is extremely difficult to deteriorate even when exposed to a moist environment. That is, the problem of inferior “adhesion durability”, which is conventionally a drawback of stainless steel sheets, is avoided. Therefore, it can be expected to maintain a high adhesive strength not only in the initial stage but also after long-term use.
From the above, the present invention contributes to the provision of environmentally friendly products having both adhesive strength reliability and recyclability in various types of kitchen equipment, kitchen appliances, and stainless steel exterior building materials.

<Roughened surface of stainless steel sheet>
The stainless steel plate targeted by the present invention has a specific roughened surface in which pits having a high anchor effect are formed at a high density. FIG. 1 illustrates an SEM photograph of the roughened surface. This photograph is an observation of the roughened surface from a direction perpendicular to the plate surface. The average pit opening diameter D of the roughened surface is 2.5 μm, the average pit depth H is 1.7 μm, the average length RSm of the contour curve element obtained from the roughness curve is 2.9 μm, and the arithmetic average roughness Ra is 0.5 μm. Moreover, the area ratio of the pit non-occurrence portion is 0% or less. As can be seen in FIG. 1, there is a sharp edge-like boundary between adjacent pits.

  Such a specific roughened surface can be formed by alternating electrolysis in a ferric chloride aqueous solution as shown in Patent Documents 5 to 7, for example. It is known that it is possible to control the area ratio and pit shape of a pit non-occurrence part according to electrolysis conditions (Patent Documents 5 to 7). It is possible to obtain a roughened surface with an area ratio of less than 30% and satisfying the above formulas (1) and (2) or the above formulas (3) and (4).

The roughened surface illustrated in FIG. 1 is produced under the following conditions.
-Original plate for electrolytic surface roughening; SUS304, 2D finishing material-Electrolyte; Ferric chloride aqueous solution containing 50 g / L of Fe3 ⁺ , 50 ° C
・ Alternating electrolytic potential; Anode electrolytic potential 0.4V _SCE , Cathodic electrolytic potential -0.6V _SCE
・ Alternating electrolysis cycle; 2.5 Hz
・ Electrolytic treatment time: 60 sec

In order to obtain a roughened surface having a maximum H as much as possible with respect to D, such as 0.4D ≦ H, and even 0.5D <H, even if satisfying the formula (2) is generally used. If the conditions are the same, it is effective to set conditions such as increasing the Fe ³⁺ concentration and lowering the electrolyte temperature. In the case of satisfying the equation (4), the same applies to the case of obtaining a roughened surface where Ra is as large as possible with respect to RSm, particularly 0.15 RSm ≦ Ra, and further 0.2 RSm ≦ Ra.

  In the roughness curve, the average length RSm of the contour curve element can be regarded as a parameter reflecting the average distance between the edge boundaries in the cross section of the stainless steel plate. The average arithmetic roughness Ra can be regarded as a parameter reflecting the average distance from the edge to the pit bottom in the cross section. More conceptually, the average length RSm of the contour curve element represents the degree of “average pit opening diameter”, and the average arithmetic roughness Ra represents the degree of “average pit depth”. Can do. Therefore, the roughened surface A targeted by the present invention can be specified as satisfying the expressions (1) and (2), and according to the parameters obtained from the roughness curve, the expressions (3) and ( 4) It can be specified as satisfying the equation.

<Adhesive structure>
FIG. 2 is a cross-sectional view schematically illustrating the bonding structure of the present invention. The stainless steel plate 10 and the object 20 are joined via the rubber adhesive layer C. The rubber adhesive layer C is a layer in which the rubber adhesive is cured. The surface on the adhesive layer C side of the stainless steel plate 10 is the roughened surface A by electrolysis described above. A large number of pits 12 are formed on the surface A, and an edge-like boundary 13 exists between adjacent pits. Between adjacent pits, there may be a pit non-occurrence portion 14 (that is, a portion where the steel plate surface before electrolysis remains), but the area ratio of the pit non-occurrence portion 14 is as small as 30% or less. The pit boundary is occupied by the edge-like boundary 13, and the existence ratio of the pit non-occurrence portion / pit boundary 15 is small compared to the existence ratio of the edge-like boundary 13. In FIG. 2, the size of the pits is drawn greatly exaggerated from the actual size.

  Part of the rubber-based adhesive layer C is embedded in the pits 12 on the roughened surface A. On the other hand, the object 20 is made of various substances that can be bonded with a rubber adhesive. Anything such as glass, ceramics, plastics, metal, and wood is acceptable. The surface B on the adhesive layer C side of the object 20 may be a smooth surface or a roughened surface having the same quality as the roughened surface A of the stainless steel plate 10. The bonding structure of the present invention is constituted by the roughened surface A of the stainless steel plate 10, the rubber-based adhesive layer C partially embedded in the pits on the surface A, and the surface B of the object 20. A surface treatment film may be formed on the outermost layer of the surface A and the surface B.

  In this adhesion structure, the area where the surfaces A and B are connected via the adhesive layer C is called “adhesion area” (reference numeral 32 in FIG. 2), and the end of the adhesion area 32 is called “adhesion edge”. Call (reference numeral 31). Further, the average thickness (that is, the average distance between the initial ABs) of the adhesive layer C that is not elastically deformed is referred to as “δ”, and the thickness direction of the adhesive layer C is referred to as “δ direction”. δ can be determined from the amount of adhesive applied using the density (known value) of the adhesive layer after curing. If the adhesive is buried in the pits of the surface A with almost no gap, δ is approximately equal to the average distance between the center line of the roughness curve of the roughened surface A and the surface B. In FIG. 2, t is the thickness of the stainless steel plate 10.

  When opposing forces in the direction perpendicular to the δ direction 33 (indicated as f and f ′ in FIG. 2) are applied to the stainless steel plate 10 and the object 20, the interface between the surface A and the adhesive layer C and the surface A shearing force acts on the interface between B and the adhesive layer C. Usually, the joint part by an adhesive agent has a strong resistance force (shear peeling strength) with respect to this shearing force. This is due to chemical bonding and does not depend much on surface irregularities. However, as described above, regarding the interface between the stainless steel and the adhesive layer, it has been a problem that a phenomenon occurs in which the shear peeling strength is reduced when exposed to a humid atmosphere.

  In the bonding structure of the present invention, a “chemical binding force” acts between the surface A of the stainless steel plate 10 and the adhesive layer C, and a part of the adhesive layer C sinks into the pits constituting the surface A. “Mechanical restraint force” due to the anchor effect is caused. By this mechanical restraining force, even when exposed to a humid atmosphere, the shear peeling strength comparable to the initial state is maintained. The characteristic that the initial shear bond strength between the stainless steel and the adhesive layer when exposed to a wet atmosphere is maintained at a high level with almost no deterioration is called “adhesion durability” in this specification. It is out. One of the major features of the adhesive structure of the present invention is that it has excellent adhesion durability.

  Usually, a rubber-based adhesive material before curing represented by a silicone rubber-based adhesive having high adhesive strength has a very high viscosity unlike a normal paint. Therefore, if the pit opening diameter of the stainless steel plate 10 is too small, the rubber-based adhesive material does not sufficiently enter the pit, so that a sufficient anchor effect cannot be exhibited, and it becomes difficult to impart adhesion durability. . As a result of various studies, it is desirable that the average diameter D of the pit openings is 2 μm or more in order to stably bring about a remarkable improvement in adhesion durability. As for the roughness parameter, it is desirable that RSm is 2 μm or more. On the other hand, it has been found that when the pit opening diameter becomes too large, the rubber-based adhesive material easily enters the pit, but becomes inferior in the anchor effect. According to the research by the inventors, it is desirable that D has a pit size of 10 μm or less. As for the roughness parameter, it is desirable that RSm is 10 μm or less. Therefore, in the present invention, the definition of the expression (1) or (3) is adopted.

  Also, if the average depth of the pits is too shallow, the anchor effect is still insufficient and a significant improvement in adhesion durability cannot be realized. Specifically, when deep pits are formed between the pit opening average diameter D and the pit average depth H so that the relationship of the above formula (2), preferably the above formula (2.1) is established, A high anchor effect is stably exerted between the rubber-based adhesive layer C. In the roughness parameter, when deep pits are formed so that the relationship of the above equation (4), preferably the above equation (4.1), is established between the average length RSm of the contour curve element and the arithmetic average roughness Ra. A high anchor effect is stably exhibited between the rubber-based adhesive layer C and the rubber-based adhesive layer C. Therefore, in the present invention, the definition of the expression (2) or (4) is adopted. When the equation (2) or (4) is not satisfied, many pits have a shallow bowl-like shape and are inferior in anchor effect. The amount of pits also affects the adhesion durability, but as a result of the examination, there is no problem if the area ratio of the pit-free portion is 30% or less.

《Demolition property》
In this specification, the ease of processing of disassembling the bonded structure by separating the two objects joined by the adhesive layer at the bonded portion is referred to as “dismantling”. FIG. 3 schematically shows a cross-sectional structure when the stainless steel plate is bent and deformed in an adhesive structure using a conventional stainless steel plate having no roughened surface A. Since the surface of the stainless steel plate 110 is not the roughened surface defined in the present invention, it is represented here as the surface A ′. By applying an external force having a stress component F parallel to the δ direction 33 in the vicinity of the bonded end portion 31 of the stainless steel plate 110, the stainless steel plate 110 is flexibly deformed. At this time, the rubber adhesive layer C is elastically deformed and follows the deflection of the stainless steel plate 110 in the region 34 in the adhesive region 32 where the distance between A′B is larger than δ. Therefore, the adhesive layer C bears the force acting in the δ direction 33 over a wide area of the region 34, and obtains enough stress (force per unit area) to peel the stainless steel plate 110 from the object 20. A very large external force is required. This is the reason why the dismantling properties of objects joined with a rubber adhesive are generally very poor.

  FIG. 4 schematically shows a cross-sectional structure in the vicinity of the bonded end when the stainless steel plate is bent and deformed in the bonded structure of the present invention using the stainless steel plate having the roughened surface A. By applying an external force having a stress component F parallel to the adhesive layer thickness direction 33 in the vicinity of the bonded end 31 of the stainless steel plate 10, a part of the stainless steel plate 10 is bent and deformed. In this case, in the region where the distance between AB is larger than δ due to the bending deformation, the adhesive layer C has a portion that enters the pit and tries to follow the bending deformation of the stainless steel plate 10, and an object outside the pit. A force in the opposite direction acts between the portion that maintains the state of being attached to the surface B of 20. In the vicinity of the edge-shaped boundary 113 at the position where the distance between AB is the largest among the edge-shaped boundaries 13 (near the bonding end portion 32), it is considered that the largest stress concentration occurs in the adhesive layer C. . At this time, in the adhesive layer C, the tears 40 and 40 ′ are generated relatively easily on both sides starting from the edge-shaped boundary 113, and the adhesive layer C can be triggered to break and separate.

  FIG. 5 schematically shows a cross-sectional structure in the process of breaking and separating the adhesive layer C in the adhesive structure of the present invention. Even after the adhesive layer C starts to break and separate from the bonded end portion 31, an external force having a stress component F parallel to the δ direction 33 is applied to the stainless steel plate 10 in the region 35 where the adhesive layer C is broken and separated. Continue to grant. As a result, the region where the distance between AB is larger than δ due to the bending deformation of the stainless steel plate 10 is expanded, and the adhesive layer C remains in the pits on the surface A, starting from the edge-like boundary 13. 41 and the part 42 adhering to the surface B of the object 20 can be broken and separated one after another. Each edge-like boundary 13 is considered to function advantageously in creating local stress concentrations in the adhesive layer C. The pit non-occurrence portion / pit boundary 15 is also considered to contribute to the generation of local stress concentration, if not the edge-like boundary 13.

  The adhesive structure of the present invention is considered to have an excellent “disassembly” by the mechanism described above. When the roughened surface A of the stainless steel plate 10 after the dismantling is actually observed, the rubber-based adhesive remains in each pit, and the adhesive layer C is substantially on the surface connecting the edge-like boundaries 13. It is confirmed that it is separated and broken along.

  In order to realize the excellent dismantling property by the above mechanism, the anchor effect to the adhesive layer C by the roughened surface A of the stainless steel plate 10 and the effect of introducing a tear to the adhesive layer C by the edge-like boundary 13 are important. is there. According to detailed examinations by the inventors, for these effects, the pits satisfying the above formulas (1) and (2), or the above formulas (3) and (4) are not included in the pit non-occurrence area. It was found that it was exhibited by a specific roughened form existing at a high density at a rate of 30% or less.

  However, an excellent dismantling property cannot be realized only by the stainless steel having such a roughened surface A. As another important technical matter, the stainless steel plate 10 is required to be easily bent and deformed. When the stainless steel plate 10 is bent and deformed, local stress concentration sufficient to introduce a tear in the adhesive layer C can be sequentially advanced from the bonded end portion 31 into the bonded region 32. Become. If the stainless steel plate 10 is close to a rigid body that hardly undergoes flexural deformation, the region 34 in which the distance between AB is larger than δ is always a very large area, so that a tear occurs in the adhesive layer C. In order to earn the necessary distance between AB, a very large external force is required. In this case, dismantling is hardly improved.

  As a result of detailed studies by the inventors, in order to peel and disassemble the stainless steel plate 10 bonded to the object 20 by the bonding structure of the present invention from the object 20, the thickness of the roughened stainless steel plate 10 is 1 It is necessary to be 0.2 mm or less. If the plate thickness becomes thicker than that, it becomes almost impossible to give the adhesive layer C enough deformation to cause a tear. Therefore, in the present invention, the stainless steel plate 10 has a thickness of 1.2 mm or less, but a thickness of 1.0 mm or less is a more preferable target. Further, when the plate thickness is about 0.6 mm or less, even when the adhesion area is wide, it is easy to peel the stainless steel plate while bending and deforming it manually, and the peeling and dismantling properties are greatly improved.

<< Evaluation of shear bond strength >>
SUS304 plate materials having various finished surfaces were prepared. Each plate thickness is 0.5 mm, and the surface finish is as follows.
BA (bright annealing finish), No. 2B (skin pass finish), No. 2D (pickling finish), No. 4 (belt polishing finish), HL (hairline polishing finish), electrolytic roughening finish (No. 2D finish) The material is subjected to electrolytic surface roughening treatment and has a rough surface as shown in FIG. 1, and the electrolysis conditions are as described above)
As an adhesive, a one-component heat-curable silicone rubber-based adhesive (XE13-B3208 manufactured by Toshiba Silicone Co., Ltd.) was prepared.

The combinations of materials to be adhered were as follows.
[Adhesive structure of the present invention example]
Both the stainless steel plate 10 and the object 20 in FIG.
Steel plate corresponding to the stainless steel plate 10 in FIG. 2; the above various finishing materials excluding the electrolytically roughened finish material. Object 20 in FIG. 2;

  A shear adhesion test piece (FIG. 6) having the adhesion structures of the present invention examples and comparative examples was produced. The bonding area is 25 mm × 25 mm. Adhesive is applied to the surface of the degreased stainless steel plate, both the stainless steel plates are bonded together, and the adhesive is cured by placing it in a furnace at 200 ° C. for 10 minutes, and then at room temperature for 24 hours or more. By curing, an adhesive structure having an adhesive area of 25 mm × 25 mm and δ of 800 μm was formed. This value of δ is the thickness at which the peel adhesion strength is almost maximized.

  In addition, some samples of the various test pieces were subjected to a water resistance deterioration test in which the samples were immersed in hot water at 98 ° C. for a maximum of 200 hours. This is an accelerated test to evaluate the adhesion water resistance when used in a humid environment.

  A “tensile shear bond strength test” based on JIS K6850 was performed on test pieces that were not subjected to the water resistance deterioration test and test pieces that were subjected to the water resistance deterioration test at various immersion times. The pulling direction is the arrow direction in FIG. FIG. 7 shows a typical “shear adhesion curve” with a silicone rubber adhesive, which is observed when this tensile test is performed. The value of the maximum stress in this curve (the position of the arrow in FIG. 7) is defined as “shear bond strength”. The number of tests was n = 5, and the average value was adopted as the shear bond strength of the joint structure.

  Fig. 8 shows the shear bond strength for various finishing materials when not subjected to a water resistance deterioration test ("before test" indication) and when subjected to a water resistance deterioration test with a soaking time of 100 hours (indicated as "after test"). The graph which compared is shown. The one located on the right in FIG. 8 has a larger surface roughness (Ra) of the stainless steel plate. In the state before the water-resistant deterioration test, it hardly depended on the surface roughness, and all exhibited high shear adhesive strength of 3 MPa or more. There is no difference due to electrolytic roughening. On the other hand, after the water resistance test, except for the electrolytic surface-roughened finish, the shear bond strength was remarkably lowered in any of the finishes, and a defect peculiar to stainless steel that the adhesion durability was poor appeared. However, in the electrolytic surface-roughened finishing material targeted in the present invention, no decrease in adhesion durability was observed. That is, according to the adhesion structure of the present invention, it was confirmed that the decrease in adhesion durability in a wet environment, which is a weak point of stainless steel, can be overcome.

  FIG. 9 exemplifies the relationship between the water resistance deterioration test time and the shear bond strength for the present invention example using an electrolytic surface-roughened material as a stainless steel plate and the comparative example using a No. 4 finish. In the No. 4 finishing material, the shear bond strength was greatly reduced at an early stage. In the case where the shear bond strength was lowered, the bond structure was broken at the interface between the stainless steel plate and the rubber adhesive layer. On the other hand, in the example of the present invention using the electrolytic surface-roughened material, no decrease in shear bond strength was observed even after a 200-hour water resistance deterioration test. This is because of the anchor effect that part of the rubber-based adhesive layer is embedded in the pits on the roughened surface, and the mechanical binding force creates a bond between the stainless steel plate and the rubber-based adhesive layer. It is thought that power was maintained high.

<< Evaluation of dismantling >>
A SUS304 plate (plate thickness 0.5 mm) having the same various finished surfaces as in Example 1 and the same silicone rubber adhesive as in Example 1 were prepared.

  A combination of materials to be bonded was made in the same manner as in Example 1 to produce a peel adhesion test piece (FIG. 10) having the bonding structures of the present invention and the comparative examples. This test piece has a T-shape that can be attached to a chuck of a tensile tester so that a tensile load can be applied in the δ direction at the bonding end, and the bonding area is 25 mm × 60 mm. An adhesive structure having δ of 800 μm was formed by the same method as in Example 1. Some samples of the various test pieces were subjected to the same water resistance deterioration test as in Example 1.

  A “peeling adhesion strength test” based on JIS K6854-3 was performed on test pieces that were not subjected to the water resistance deterioration test and test pieces that were subjected to the water resistance deterioration test at various immersion times. The pulling direction is the arrow direction in FIG. Here, the amount of tensile displacement by the tensile tester (the amount of displacement between the checks) is called the “peeling length”, and in the load-displacement curve (hereinafter referred to as “peeling curve”) measured by the tensile tester, A value obtained by converting an average load with a separation length of 20 to 60 mm into a stress per unit width (N / mm) is defined as “average adhesive strength” of the test piece. The number of tests was n = 5, and the average value of the average adhesive strength was adopted as the “peeling adhesive strength” of the joint structure.

  FIG. 11 shows the peel adhesion strength for various finishing materials when not subjected to a water resistance deterioration test (indicated as “before test”) and when subjected to a water resistance deterioration test with an immersion time of 100 hours (indicated as “after test”). The graph which compared is shown. Each conventional finishing material exhibits a very large peel adhesion strength before the water resistance deterioration test, and it is not easy to disassemble the adhesion structure. However, after the water resistance deterioration test, the peel adhesion strength is reduced to near zero. On the other hand, in the adhesive structure of the present invention using the electrolytic surface-roughened finish, it can be seen that the peel adhesive strength before the water resistance deterioration test is very small and disassembly is easy. Further, the peel adhesion strength does not change greatly even after the water resistance deterioration test, and good dismantling properties are maintained.

  FIG. 12 illustrates the relationship between the water resistance degradation test time and the peel adhesion strength for the present invention example using an electrolytic surface-roughened material as a stainless steel plate and the comparative example using a No. 4 finish. In the example of the present invention using the electrolytic surface-roughened material, no significant change is observed in the peel adhesion strength even after the 200-hour water resistance deterioration test.

  By observing the fracture surface of the test piece before the water resistance deterioration test, which was dismantled by performing the peel adhesion strength test, all of the conventional finishing materials with high peel adhesion strength had cohesive failure inside the adhesive layer. The broken adhesive layer adhered equally to the surfaces of both stainless steel plates. On the other hand, in the adhesive structure of the present invention using the electrolytic roughening finish, as shown schematically in FIG. 5, the adhesive layer is opposite to the portion remaining in the pits on the electrolytic roughened surface. It was broken and separated into the part adhering to the surface of the stainless steel plate. As a result of analyzing the roughened electrolytic surface after rupture separation by EPMA, it was confirmed that Si, which is a component of the silicone rubber-based adhesive, was present at a high concentration at a position corresponding to the pit. It was proved that the fracture form was such that the portion remained in the pits on the electrolytic roughened surface.

  FIG. 13 illustrates an exfoliation curve and a cross-sectional photograph in the middle of delamination for the bonding structure of No. 4 finishing material, which is a comparative example, and the bonding structure of electrolytic roughening finishing material, which is an example of the present invention. As can be seen from the cross-sectional photograph in the middle of peeling, in the No. 4 finishing material, the silicone rubber adhesive layer is greatly elastically deformed to follow the displacement of the steel plate at the part where the distance between the steel plates (SUS) is larger than the initial distance. is doing. On the other hand, in the example using the electrolytically roughened finish, most of the silicone rubber adhesive layer adheres to the surface of the steel plate on the upper side of the photograph where the distance between the steel sheets (SUS) is larger than the initial distance. It can be seen that the silicone rubber adhesive layer is easily separated from the lower steel plate (shown as roughened SUS) with almost no elastic deformation. In this case, although both the upper and lower steel plates are electrolytically roughened finishes, the fracture separation progressed along the steel plate surface on the side where fracture separation first occurred as shown in FIG. it is conceivable that.

<< Influence of roughened surface A >>
In the bonding structures of the inventive examples of Examples 1 and 2, the electrolytic roughening finish was changed to the following stainless steel plates, and the same experiment as in Examples 1 and 2 was performed. RSm and Ra were measured using a laser microscope under the following conditions.
(Laser microscope measurement conditions)
-Apparatus; Scanning confocal laser microscope (Olympus, OLS1200)
Ar laser: 5 mW output, 488 nm wavelength, resolution: 0.01 μm
・ Measurement area: 50 × 50μm

[Example 1 (comparative example)]
(Electrolysis conditions)
-Original plate for electrolytic surface roughening; SUS304, 2D finishing material-Electrolyte; Ferric chloride aqueous solution containing 70 g / L of Fe3 ⁺ , 50 ° C
・ Alternating electrolytic potential; Anode electrolytic potential 0.4V _SCE , Cathodic electrolytic potential -0.7V _SCE
・ Alternating electrolysis cycle; 2.5 Hz
・ Electrolytic treatment time: 60 sec

(Roughened form)
D = 3.9 μm, H = 2.1 μm, RSm = 4.1, Ra = 0.7, area ratio of pit non-occurrence portion; more than 30% (evaluation result)
The anchor effect was insufficient because the area ratio of the pit-free portion exceeded 30%, and the shear bond strength after 100 hours of the water resistance deterioration test was below 2.0 MPa.

[Example 2 (Invention)]
(Electrolysis conditions)
-Original plate for electrolytic surface roughening; SUS304, 2B finishing material-Electrolytic solution; Ferric chloride aqueous solution containing 110 g / L of Fe3 ⁺ , 30 ° C
・ Alternative electrolysis potential; Anode electrolysis potential 0.8V _SCE , Cathode electrolysis potential -1.2V _SCE
・ Alternating electrolysis cycle; 0.5 Hz
・ Electrolytic treatment time: 60 sec

(Roughened form)
D = 8.9 μm, H = 4.5 μm, RSm = 9.2, Ra = 1.4, area ratio of pit non-occurrence portion: 30% or less (evaluation result)
The shear bond strength was good at 3.0 MPa or more at a water resistance degradation test time of 0 to 200 hours, and the peel adhesion strength was good at 5 N / mm or less at a water resistance degradation test time of 0 to 200 hours.

[Example 3 (Example of the present invention)]
(Electrolysis conditions)
-Original plate for electrolytic surface roughening; SUS430, BA finishing material-Electrolytic solution; Ferric chloride aqueous solution containing 10 g / L of Fe3 ⁺ , 50 ° C
・ Alternative electrolysis potential; anode electrolysis potential 2.0V _SCE , cathode electrolysis potential -0.6V _SCE
・ Alternating electrolysis cycle; 3.3 Hz
・ Electrolytic treatment time: 15 sec

(Roughened form)
D = 2.2 μm, H = 1.2 μm, RSm = 2.5, Ra = 0.4, pit non-occurrence area ratio: 30% or less (evaluation result)
The shear bond strength was good at 3.0 MPa or more at a water resistance degradation test time of 0 to 200 hours, and the peel adhesion strength was good at 5 N / mm or less at a water resistance degradation test time of 0 to 200 hours.

[Example 4 (comparative example)]
(Electrolysis conditions)
-Original plate for electrolytic surface roughening; SUS430, BA finishing material-Electrolytic solution; Ferric chloride aqueous solution containing 10 g / L of Fe3 ⁺ , 50 ° C
・ Alternating electrolysis potential; Anode electrolysis potential 1.0V _SCE , Cathode electrolysis potential -1.8V _SCE
・ Alternating electrolysis cycle; 2.5 Hz
・ Electrolytic treatment time: 60 sec

(Roughened form)
D = 5.4 μm, H = 1.0 μm, RSm = 5.8, Ra = 0.3, area ratio of pit non-occurrence portion: 30% or less (evaluation result)
The anchor effect was insufficient due to the shallow bowl-shaped pit shape that deviated from the expression (2), and the shear bond strength after 100 hours of the water resistance deterioration test was less than 2.0 MPa. Moreover, the peel adhesion strength exceeded 5 N / mm before the water resistance deterioration test, and was inferior in peeling and dismantling properties as compared with the example of the present invention.

[Example 5 (comparative example)]
(Electrolysis conditions)
-Original plate for electrolytic surface roughening; SUS304, 2B finishing material-Electrolytic solution; Ferric chloride aqueous solution containing 110 g / L of Fe3 ⁺ , 30 ° C
・ Alternating electrolysis potential; anode electrolysis potential 1.0V _SCE , cathode electrolysis potential -0.8V _SCE
・ Alternating electrolytic cycle; 0.25Hz
・ Electrolytic treatment time: 60 sec

(Roughened form)
D = 18.0 μm, H = 10.3 μm, RSm = 20.1, Ra = 3.2, Area ratio of pit non-occurrence portion: 30% or less (evaluation result)
The anchor effect was insufficient because D was too large outside the definition of formula (1), and the shear bond strength after 100 hours of the water resistance deterioration test was less than 2.0 MPa.

[Example 6 (comparative example)]
(Electrolysis conditions)
-Original plate for electrolytic surface roughening; SUS304, 2B finishing material-Electrolytic solution; Ferric chloride aqueous solution containing 110 g / L of Fe3 ⁺ , 30 ° C
・ Alternative electrolysis potential; Anode electrolysis potential 0.8V _SCE , Cathode electrolysis potential -0.6V _SCE
・ Alternating electrolytic cycle; 15.0Hz
・ Electrolytic treatment time: 60 sec

(Roughened form)
D = 0.2 μm, H = 0.1 μm, RSm = 0.17, Ra = 0.03, area ratio of pit non-occurrence portion: 30% or less (evaluation result)
Since D is too small outside the definition of formula (1), the adhesive does not sufficiently penetrate into the pit, the anchor effect is insufficient, and the shear bond strength after 100 hours of the water resistance deterioration test is less than 2.0 MPa. It was.

Example 7 (Invention Example)
(Electrolysis conditions)
-Original plate for electrolytic surface roughening; SUS430, No. 2B finishing material-Electrolytic solution; Ferric chloride aqueous solution containing 20 g / L of Fe3 ⁺ , 50 ° C
・ Alternating electrolytic current density; Anode current density 3.0 kA / m ² , Cathode current density 0.2 kA / m ²
・ Alternating electrolytic cycle; 5Hz
・ Electrolytic treatment time: 60 sec

(Roughened form)
D = 3.0 μm, H = 2.7 μm, RSm = 2.9, Ra = 0.88, area ratio of pit-free portion; 30% or less Roughness measured with a laser microscope on this roughened surface An example of a curve profile is illustrated in FIG. In the figure, the unit is μm for both the vertical axis and the horizontal axis (the same applies to FIGS. 15A, 15B, and 15D described later).
(Evaluation results)
The shear bond strength was good at 3.0 MPa or more at a water resistance degradation test time of 0 to 200 hours, and the peel adhesion strength was good at 5 N / mm or less at a water resistance degradation test time of 0 to 200 hours.

[Example 8 (Example of the present invention)]
(Electrolysis conditions)
-Original plate for electrolytic surface roughening; SUS304, No. 2B finishing material-Electrolyte; Ferric chloride aqueous solution containing 55 g / L of Fe3 ⁺ , 57.5 ° C
・ Alternating electrolysis current density; anode current density 3.0 kA / m ² , cathode current density 1.0 kA / m ²
・ Alternating electrolytic cycle; 5Hz
・ Electrolytic treatment time: 60 sec

(Roughened form)
D = 2.4 μm, H = 2.85 μm, RSm = 2.2, Ra = 1.04, area ratio of pit-free portion; 30% or less Roughness measured with a laser microscope on this roughened surface An example of a curve profile is illustrated in FIG.
(Evaluation results)
The shear bond strength was good at 3.0 MPa or more at a water resistance degradation test time of 0 to 200 hours, and the peel adhesion strength was good at 5 N / mm or less at a water resistance degradation test time of 0 to 200 hours.

Example 9 (Invention Example)
(Electrolysis conditions)
-Original plate for electrolytic surface roughening; NSS445J1, No.2D finishing material-Electrolyte; Ferric chloride aqueous solution containing 30 g / L of Fe3 ⁺ , 50 ° C
・ Alternating electrolytic current density; anode current density 3.0 kA / m ² , cathode current density 0.8 kA / m ²
・ Alternating electrolytic cycle; 5Hz
・ Electrolytic treatment time: 60 sec

(Roughened form)
D = 2.8 μm, H = 1.8 μm, RSm = 2.6, Ra = 0.59, area ratio of pit-free portion; 30% or less (evaluation result)
The shear bond strength was good at 3.0 MPa or more at a water resistance degradation test time of 0 to 200 hours, and the peel adhesion strength was good at 5 N / mm or less at a water resistance degradation test time of 0 to 200 hours.

For comparison, only the “peeling adhesion strength test” shown in Example 2 was carried out using a pickling material pickled under the following conditions in place of the electrolytic roughening finish. The test piece used was not subjected to the water resistance deterioration test.
(Pickling conditions)
・ Pickling solution: 8 mass HNO ₃ +3 mass% HF, 50 ° C.
・ Immersion time: 4 min

[Example 10 (comparative example)]
(Steel grade)
SUS430
(Surface roughness)
RSm = 9.5, Ra = 0.39
An example of the roughness curve profile measured using a laser microscope for this surface is illustrated in FIG.
(Evaluation results)
The peel adhesion strength was greater than 10 N / mm and the dismantling property was poor.

[Example 11 (comparative example)]
(Steel grade)
SUS304
(Surface roughness)
RSm = 14.4, Ra = 0.43
An example of the roughness curve profile measured using a laser microscope for this surface is illustrated in FIG.
(Evaluation results)
The peel adhesion strength was greater than 10 N / mm and the dismantling property was poor.

[Example 12 (comparative example)]
(Steel grade)
NSS445M2
(Surface roughness)
RSm = 4.4, Ra = 0.13
(Evaluation results)
The peel adhesion strength was greater than 10 N / mm and the dismantling property was poor.

The SEM photograph about the roughened surface of the stainless steel plate used as the object of the present invention. The figure which illustrated typically the adhesion structure of the present invention. The figure which showed typically the cross-section when a stainless steel plate was bent and deformed in the adhesion structure using the conventional stainless steel plate which does not have the roughening surface A. The figure which showed typically the cross-sectional structure when deform | transforming a stainless steel plate in the adhesive structure of this invention using the stainless steel plate which has the roughened surface A. The figure which showed typically the cross-section of the process in which the fracture | rupture separation of the adhesive bond layer C is advancing in the adhesive structure of this invention. The figure which showed typically the dimension and the shape of a shear bonding test piece. The figure which illustrated the typical shearing adhesion curve by a silicone rubber adhesive. The graph which compared the shearing adhesive strength when not using for a water-resistant deterioration test, and when using for the water-resistant deterioration test of immersion time 100 hours about various finishing materials. The graph which illustrated the relationship between the water-resistant deterioration test time and shear bond strength about the example of the present invention using the electrolytic surface-roughening processing material as a stainless steel plate, and the comparative example using No. 4 finishing material. The figure which showed typically the dimension and shape of a peeling adhesion test piece. The graph which compared the peeling adhesive strength when not using for a water-resistant deterioration test, and when using for the water-resistant deterioration test of immersion time 100 hours about various finishing materials. The graph which illustrated the relationship of the water-resistant deterioration test time and the peeling adhesive strength about the example of this invention using the electrolytic roughening processing material as a stainless steel plate, and the comparative example using No. 4 finishing material. The figure which illustrated the peeling curve and the cross-sectional photograph in the middle of peeling about the junction structure of the No. 4 finishing material which is a comparative example, and the joining structure of the electrolytic roughening finishing material which is the example of this invention. The figure which showed typically the cross-sectional shape of the stainless steel plate which has the roughening surface A. FIG. The figure which showed an example of the roughness curve profile measured using the laser microscope about the roughening surface A of this invention object, and the pickling surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Stainless steel plate 12 Pit 13, 113 Edge-like boundary 14 Pit non-occurrence part 15 Pit non-occurrence part / pit boundary 20 Object 31 Adhesion end part 32 Adhesion area 33 δ direction 40, 40 'Rip 41 41 The remaining part 42 The part where the adhesive layer C adheres to the surface B of the object

Claims (3)

It consists of a roughened surface A that satisfies the following condition (X), a surface B of the object, and a rubber-based adhesive layer C interposed between AB formed on the surface of a stainless steel plate with a thickness of 1.2 mm or less. The stainless steel plate / object bonding structure with excellent demolition property, in which the rubber adhesive layer C is embedded in the pits of the roughened surface A and adheres to the stainless steel plate.
(X): The pits are formed with a high density so that the area ratio of the pit non-occurrence portion is 30% or less, and the pit opening average diameter D (μm) and pit average depth H (μm) are the following (1) Electrolytic roughened surface satisfying the equation (2) and having an edge-like boundary between adjacent pits 2 ≦ D ≦ 10 (1)
0.3D ≦ H (2) It consists of a roughened surface A that satisfies the following condition (Y) formed on the surface of a stainless steel plate having a thickness of 1.2 mm or less, a surface B of the object, and a rubber-based adhesive layer C interposed between the AB. The stainless steel plate / object bonding structure with excellent demolition property, in which the rubber adhesive layer C is embedded in the pits of the roughened surface A and adheres to the stainless steel plate.
(Y); the average length RSm (μm) and arithmetic average roughness Ra of the contour curve element defined in JIS B0601 (2001) in the roughness curve of the surface A when the area ratio of the pit non-occurrence portion is 30% or less (Μm) satisfies the relationship of the following formulas (3) and (4), and has an electrolytic roughened surface having edge-like boundaries between adjacent pits 2 ≦ RSm ≦ 10 (3)
0.1RSm ≦ Ra (4) 3. The adhesive structure according to claim 1 or 2, wherein an area where the surfaces A and B are connected via an adhesive layer C is an "adhesion area", an end of the adhesion area is an "adhesion end", and is elastically deformed. When the average thickness of the non-adhesive layer C (that is, the average distance between the initial ABs) is referred to as “δ” and the thickness direction of the adhesive layer C is referred to as the “δ direction”,
By applying an external force having a stress component in the δ direction to the bonded end of the stainless steel plate having the surface A to cause the stainless steel plate to bend and deform in the vicinity of the bonded end, the bonded end where the distance between AB is larger than δ, Breaking and separating the adhesive layer C into a portion remaining in the pits on the surface A and a portion adhering to the surface B of the object;
Thereafter, the external force having a stress component in the δ direction is continuously applied to the stainless steel plate in the region where the adhesive layer C is broken and separated, and the region where the distance between AB becomes larger than δ due to the flexural deformation is expanded. A method for disassembling a bonded structure between a stainless steel plate and an object, in which the layer C is broken and separated one after another into a part remaining in the pits on the surface A and a part adhering to the surface B of the object.