Adhesive joint structure and automotive component

Abstract

The adhesive joint structure is provided with a first member, a second member, and an adhesive layer that joins the first member and the second member, the first member and / or the second member has a steel material and a plating layer, the surface of the plating layer is formed into a concavo-convex surface, and in the cross section of the plating layer, the thickness of the plating layer is greater than the thickness of the first member and the thickness of the second member. The relationship between the length (Lo) of the plating layer in the longitudinal direction in the observation region of the cross section and the total length (Lr) of the contour line of the surface of the plating layer in the observation region satisfies the following formula (1). At least some of the plurality of block-shaped binary eutectic structures or the plurality of block-shaped ternary eutectic structures contained in the plating layer continuously exist from the surface of the plating layer to a position that is 1 / 2 of the average thickness of the plating layer. (1) (Lr-Lo) / Lo * 100 > = 2.0 (%).

Description

Technical Field

[0001] This disclosure relates to adhesive bonding structures and automotive components.

[0002] This application claims priority based on Japanese Patent Application No. 2023-087181 filed on May 26, 2023, the contents of which are incorporated herein by reference. Background Technology

[0003] In the automotive and other transportation equipment industries, the use of adhesives in the jointing of components is increasing for purposes such as improving body rigidity, assisting in weld fracture prevention, and joining dissimilar materials. Significant performance improvements can be expected by using adhesives to join components together, making it an important means of vehicle body lightweighting. Therefore, various studies have been conducted to improve the joint strength between components when developing adhesive-bonded structures for metal components or metal components with other materials as body parts.

[0004] For example, in the following Patent Document 1, a technique is proposed that uses an aluminum alloy material having a predetermined oxide film formed on the surface of an aluminum alloy substrate, and then having a film having siloxane bonds formed on the oxide film, to bond the aluminum alloy materials to each other or to other components via an adhesive resin.

[0005] Furthermore, in the following Patent Document 2, a technique is proposed that uses a chemically converted metal plate on the surface of a metal substrate to form a chemically converted film containing a water-soluble resin and a lubricant having carbon-oxygen bonds, and the chemically converted metal plate is bonded to the resin layer through an adhesive layer.

[0006] Furthermore, Zn-Al-Mg hot-dip galvanized steel with a Zn layer containing Al and Mg exhibits excellent corrosion resistance. Therefore, for example, the application of Zn-Al-Mg hot-dip galvanized steel sheets obtained by hot-dip galvanizing high-strength steel sheets to automotive components has been studied. As Zn-Al-Mg hot-dip galvanized steels, for example, the hot-dip galvanized steels described in Patent Documents 3 and 4 are known.

[0007] Existing technical documents Patent documents Patent Document 1: International Publication No. 2016 / 076344 Patent Document 2: International Publication No. 2017 / 169571 Patent Document 3: International Publication No. 2018 / 139619 Patent Document 4: International Publication No. 2018 / 139620 Summary of the Invention

[0008] The problem that the invention aims to solve However, when adhesives are used to join components together, the performance degradation of the components due to adhesive deterioration (reduced adhesion) is unavoidable. This applies to both the technologies disclosed in Patent Documents 1 and 2. Therefore, the application of adhesives is difficult to guarantee in real-world conditions, and its application is sometimes limited depending on the location, or its deterioration may be anticipated in the design. Furthermore, the application of Zn-Al-Mg hot-dip galvanized steel with excellent corrosion resistance to automotive components has been studied, but techniques to improve the adhesion between Zn-Al-Mg hot-dip galvanized steel and the adhesive layer have not been investigated.

[0009] This disclosure was made in view of the above-mentioned problems. The objective is to provide an adhesive-bonded structure and automotive parts that are manufactured by bonding components formed from Zn-Al-Mg based coated steel to other components using an adhesive, and that exhibit excellent adhesive durability and end-face corrosion resistance.

[0010] Methods for solving problems To address the aforementioned issues, this disclosure adopts the following structure.

[0011] [1] An adhesive bonding structure comprising: Component 1 The second component, and An adhesive layer that joins the first component and the second component. Wherein, either or both of the first component or the second component are plated steel, the plated steel having steel material and a coating disposed on at least a portion of the surface of the steel material. The average chemical composition of the above coating, expressed in % by mass, includes: Al: 10.00~30.00% Mg: 1.00~15.00%, Sn: 0.00~1.00% Si: 0.00~2.00% Ca: 0.00~2.00% Ni: 0.00~1.00% Fe: 0.01~15.00%, Sb: 0.00~0.50%, Pb: 0.00~0.50%, Cu: 0.00~1.00%, Ti: 0.00~1.00%, Cr: 0.00~1.00% Nb: 0.00~1.00%, Zr: 0.00~1.00% Mn: 0.00~1.00% Mo: 0.00~1.00% Ag: 0.00~1.00%, Li: 0.00~1.00% Bi: 0.00~1.00% V: 0.00~1.00% Co: 0.00~1.00%, In: 0.00~1.00%, W: 0.00~1.00% P: 0.00~1.00% La: 0.00~0.50% Ce: 0.00~0.50% B: 0.00~0.50% Y: 0.00~0.50% Sr: 0.00~0.50%, Total of Sb, Pb, Cu, Ti, Cr, Nb, Zr, Mn, Mo, Ag, Li, Bi, V, Co, In, W, P, La, Ce, B, Y, Sr: 0.00~5.00%, Remaining components: Zn and impurities. The surface of the above-mentioned coating is made into an uneven surface. In the cross section of the above-mentioned coating, the relationship between the length Lo of the coating in the longitudinal direction within the observation area of ​​the above-mentioned cross section and the total length Lr of the outline of the surface of the coating in the observation area satisfies the following equation (1). The aforementioned coating contains one or both of the following: multiple blocky binary eutectic structures or multiple blocky ternary eutectic structures. At least a portion of the aforementioned blocky binary eutectic structures or the aforementioned blocky ternary eutectic structures are continuously present from the surface of the coating up to a position where the average thickness of the coating is 1 / 2.

[0012] (Lr-Lo) / Lo×100≥2.0 (%) (1) [2] According to the adhesive bonding structure described in [1], the first component is the plated steel having the steel and the coating described above. The second component mentioned above is any one of alloyed hot-dip galvanized steel, fiber-reinforced plastic, aluminum alloy, or magnesium alloy.

[0013] [3] According to the adhesive bonding structure described in [1], the plated steel material includes the steel material, the plating layer, and at least a film portion disposed on the uneven surface of the plating layer. The adhesive layer connects the first component and the second component through the film portion.

[0014] [4] According to the adhesive bonding structure described in [2], the plated steel material includes the steel material, the plating layer, and at least a film portion disposed on the uneven surface of the plating layer. The adhesive layer connects the first component and the second component through the film portion.

[0015] [5] According to the adhesive bonding structure described in [3] or [4], wherein the above-mentioned film portion contains: an organic resin phase comprising one or more of urethane groups, epoxy groups, and ester groups, and an organic compound phase formed from an organosilicon compound comprising at least one of Si-O bonds or Si-OH bonds and Si-C bonds. When Ar sputtering is performed on the film portion from the adhesive layer side toward the coating layer side at any location including the interface between the coating and the film portion, and the analysis is performed using time-of-flight secondary ion mass spectrometry. Peaks corresponding to Si-O-Me bonds were observed, and the value obtained by dividing the count of the aforementioned Si-O-Me bond peaks by the sum of all two ion counts detected within the mass scan range m / z = 0 to 300 was 1.0 × 10⁻⁶. -3 above.

[0016] Wherein, Me is one or more of the elements Zn, Al, Mg or Fe that constitute the above coating.

[0017] [6] According to the adhesive bonding structure described in [1], the coating includes an Fe-Al interface alloy layer in contact with the steel. At least a portion of the aforementioned blocky binary eutectic structures or the aforementioned blocky ternary eutectic structures are continuously present from the surface of the aforementioned coating up to the aforementioned Fe-Al interfacial alloy layer.

[0018] [7] According to the adhesive joint structure described in [1], wherein, instead of the above formula (1), the following formula (2) is satisfied. The number of portions in which at least a portion of the aforementioned blocky binary eutectic structure or the aforementioned blocky ternary eutectic structure continuously exists from the surface of the coating up to a position where the average thickness of the coating is 1 / 2 is 3 to 15 portions in each rectangular region of 500 μm long side and 150 μm short side on the surface of the coating.

[0019] (Lr-Lo) / Lo×100≥6.0 (%) (2) [8] According to the adhesive joint structure described in [1], wherein, instead of the above formula (1), the following formula (3) is satisfied. The number of portions in which at least a portion of the aforementioned blocky binary eutectic structure or the aforementioned blocky ternary eutectic structure continuously exists from the surface of the coating up to a position where the average thickness of the coating is 1 / 2 is 5 to 15 portions in each rectangular region of 500 μm long side and 150 μm short side on the surface of the coating.

[0020] (Lr-Lo) / Lo×100≥8.0 (%) (3) [9] According to the adhesive bonding structure described in [1], at least a portion of the plurality of blocky binary eutectic structures or the plurality of blocky ternary eutectic structures are continuously present from the surface of the coating up to a position of 1 / 2 of the average thickness of the coating in the recess of the convex and concave surface of the coating.

[0021]

[10] According to the adhesive bonding structure described in [6], at least a portion of the plurality of blocky binary eutectic structures or the plurality of blocky ternary eutectic structures are located in the recess of the convex and concave surfaces of the coating from the surface of the coating to the portion where the Fe-Al interface alloy layer is continuously present.

[0022]

[11] According to the adhesive bonding structure described in [1], in the average chemical composition of the above coating, for Al and Mg, Al: 10.00-25.00% and Mg: 4.50-15.00%.

[0023]

[12] According to the adhesive bonding structure described in [1], in the average chemical composition of the above coating, for Al and Mg, Al: 15.00-22.00% and Mg: 5.00-15.00%.

[0024]

[13] An adhesive bonding structure according to any one of [1],

[11] or

[12] , wherein Sn is 0.05 to 0.50% in the average chemical composition of the coating. The above coating contains a Mg2Sn phase, which was detected by X-ray diffraction.

[0025]

[14] The adhesive bonding structure according to [1],

[11] or

[12] , wherein the average chemical composition of the above coating contains one or both of La and Ce, and the total amount of La and Ce is 0.05 to 0.50%.

[0026]

[15] According to the adhesive bonding structure described in

[13] , the average chemical composition of the above coating contains one or both of La and Ce, and the total amount of La and Ce is 0.05 to 0.50%.

[0027]

[16] An adhesive joint structure according to any one of [1] to [4], wherein the first member and the second member are further joined by a second joint.

[0028]

[17] According to the adhesive joint structure described in

[16] , the second joint is a spot weld.

[0029]

[18] An automotive component having an adhesive bonding structure as described in any one of [1] to [4] or [6] to

[12] .

[0030]

[19] An automotive component having the adhesive bonding structure described in [5].

[0031]

[20] An automotive component having the adhesive bonding structure described in

[13] .

[0032]

[21] An automotive component having the adhesive bonding structure described in

[14] .

[0033]

[22] An automotive component having the adhesive bonding structure described in

[15] .

[0034]

[23] An automotive component having the adhesive bonding structure described in

[16] .

[0035]

[24] An automotive component having the adhesive bonding structure described in

[17] .

[0036] Invention Effects As explained above, the present disclosure provides an adhesive bonding structure with excellent adhesion durability and corrosion resistance, which is manufactured by bonding components formed from Zn-Al-Mg based coated steel to other components using an adhesive. The adhesive bonding structure is also provided for automotive components. Attached Figure Description

[0037] Figure 1-1 This is a schematic perspective view of an adhesive bonding structure according to an embodiment of the present disclosure.

[0038] Figure 1-2 This is a schematic cross-sectional view of galvanized steel as an example of the first component.

[0039] Figure 1-3 This is a schematic diagram illustrating an example of the field of view when observing a cross-section of the coating on coated steel using a scanning electron microscope.

[0040] Figure 1-4 This is a schematic diagram illustrating an example of the field of view when observing a cross-section of the coating on coated steel using a scanning electron microscope.

[0041] Figure 1-5 This is a schematic diagram illustrating an example of the field of view when observing the cross-section of a conventionally coated steel material using a scanning electron microscope.

[0042] Figure 2-1 yes Figure 1-1 An enlarged schematic diagram of the bonding area of ​​the adhesive joint structure shown.

[0043] Figure 2-2 yes Figure 1-1 A partially enlarged cross-sectional view of the bonding area of ​​the adhesive joint structure shown.

[0044] Figure 3 This is an enlarged schematic diagram illustrating the adhesive region of an adhesive joint structure involved in a variation of this disclosure.

[0045] Figure 4 This is a schematic perspective view of an adhesive joint structure involved in other variations of this disclosure.

[0046] Figure 5 This is a schematic perspective view of an adhesive joint structure involved in other variations of this disclosure.

[0047] Figure 6 This is a schematic diagram illustrating the bonding state of the adhesive joint structure involved in other variations of this disclosure.

[0048] Figure 7 This is a flowchart illustrating an example of a method for manufacturing an adhesive bonding structure according to an embodiment of the present disclosure. Detailed Implementation

[0049] The inventors of this invention have studied methods to improve the adhesion of the adhesive layer to the coating. In the metal microstructure of Zn-Al-Mg hot-dip coatings containing Al, Mg, and Zn, various phases or structures are contained. For example, it is known that Al and MgZn2 phases crystallize in the early stage of solidification, and binary or ternary eutectic structures crystallize in the later stage of solidification. The inventors of this invention have conducted research and found that binary or ternary eutectic structures exhibit superior adhesion to the adhesive layer compared to Al and MgZn2 phases.

[0050] However, in conventional Zn-Al-Mg hot-dip coatings, binary or ternary eutectic structures are sometimes exposed on the coating surface. Moreover, these binary or ternary eutectic structures are mostly distributed in the surface layer of the coating, specifically from the surface to a depth of 1 / 4 to 1 / 3 of the average coating thickness. Previously, it was believed that these eutectic structures exposed on the coating surface improved the adhesion of the adhesive layer. However, when manufacturing automotive components from coated steel sheets, various processing steps are required to obtain the desired shape of the automotive component. Sometimes, due to strain during processing, fine cracks develop on the surface of the processed coating. It has been found that if such cracks occur around the eutectic structures exposed on the coating surface, the eutectic structures surrounded by the cracks sometimes detach from the coating, causing so-called powdering or peeling, which does not contribute to improving the adhesion of the adhesive layer.

[0051] In particular, Zn-Al-Mg hot-dip coatings are harder than previous Zn-based coatings, which may lead to more cracks and an increased frequency of eutectic structure detachment from the coating, raising concerns about reduced adhesion of the adhesive layer.

[0052] Furthermore, the uneven surface of the coating, compared to a flat surface, is expected to improve the adhesion of the adhesive layer.

[0053] Therefore, the inventors conducted research and discovered that by applying a hot-dip galvanizing bath to steel using a hot-dip galvanizing method, and by controlling the atmosphere from the time the plating bath is removed until cooling begins, adjusting the cooling rate during cooling, and selecting a suitable cooling gas, a binary or ternary eutectic structure can be continuously present at a depth deeper than the surface of the coating, specifically at least from the surface of the coating to a depth of 1 / 2 the average thickness of the coating. Even if cracks occur, the eutectic structure will not detach from the coating, thereby preventing a decrease in the adhesion of the adhesive layer and inhibiting the deterioration of adhesive durability. Furthermore, it was discovered that by controlling the atmosphere, adjusting the cooling rate, and selecting a suitable cooling gas, the surface of the coating can be made uneven, which can further improve adhesive durability.

[0054] Furthermore, studies were conducted to further improve adhesive durability. The results showed that by providing a film portion between the plated steel and the adhesive layer, this film portion containing substances capable of forming strong chemical bonds with the plating layer of the plated steel and substances with high affinity for the resin of the adhesive constituting the adhesive layer, although water intrusion into the adhesive interface between the plated steel and the adhesive layer is considered a factor contributing to reduced adhesion, the film portion inhibits this water intrusion, thereby further improving adhesive durability. It should be noted that the film portion is an optional component in this disclosure.

[0055] Hereinafter, the adhesive bonding structure and automotive component, which are embodiments of the present disclosure, will be described with reference to the accompanying drawings. It should be noted that in this specification and the accompanying drawings, constituent elements that have substantially the same functional configuration are omitted from repeated description by using the same reference numerals.

[0056] (Regarding the composition of adhesive bonding structures) Figure 1-1 This is a schematic perspective view showing the overall adhesive bonding structure according to the embodiments of this disclosure.

[0057] Figure 1-1 The adhesive bonding structure 1 shown has a first member 2 and a second member 3. The first member 2 is a so-called cap-shaped metal member. That is, the first member 2 has a web portion, a pair of longitudinal wall portions connected to the two sides of the web portion in the width direction, and a pair of flange portions connected to these longitudinal wall portions, and the first member 2 is a cap-shaped metal member with a cross-sectional shape perpendicular to the length direction. The web portion has a rectangular shape that is longer in one direction. Moreover, the second member 3 has a shape along the inner side of the web portion of the first member 2, and is bonded to the first member 2 in the bonding area 5 located inside the web portion by an adhesive layer 4. Here, the inner side of the web portion refers to the area enclosed by the web portion and the longitudinal wall portions.

[0058] It should be noted that, in order to facilitate the explanation of the structure of the adhesive bonding structure involved in this embodiment, in Figure 1-1 In this embodiment, the first component 2 is described with a cap-shaped form as a premise. However, as will be explained below, the shapes of the components constituting the adhesive bonding structure are not limited to those shown in the illustration. Furthermore, in this embodiment, it is sufficient that at least the first component 2 is plated steel. However, in the following description, as an example, the case where both the first component 2 and the second component 3 are plated steel will be described. The following description of the structure in the adhesive region 5 will refer to... Figure 1-1 Please provide an explanation.

[0059] <Regarding Component 1, Part 2> The first component 2 is, for example, made of plated steel 21 as described below. The plated steel 21 will be described below. It should be noted that in the following description, the first component 2 is defined as plated steel, but the adhesive bonding structure involved in this embodiment is not limited to this; the second component 3 may also be plated steel, or both the first component 2 and the second component 3 may be plated steel.

[0060] Coated Steel 21 The first component 2 is formed of plated steel 21. The plated steel has steel and a coating disposed on at least a portion of the surface of the steel.

[0061] The average chemical composition of the coating, by mass%, includes Al: 10.00–30.00%, Mg: 1.00–15.00%, Sn: 0.00–1.00%, Si: 0.00–2.00%, Ca: 0.00–2.00%, Ni: 0.00–1.00%, Fe: 0.01–15.00%, Sb: 0.00–0.50%, Pb: 0.00–0.50%, Cu: 0.00–1.00%, Ti: 0.00–1.00%, Cr: 0.00–1.00%, Nb: 0.00–1.00%, Zr: 0.00–1.00%, Mn: 0.00–1.00%, Mo: 0.00–1.00%, Ag: 0.00–1.00%. 0.00%, Li: 0.00~1.00%, Bi: 0.00~1.00%, V: 0.00~1.00%, Co: 0.00~1.00%, In: 0.00~1.00%, W: 0.00~1.00%, P: 0.00~1.00%, La: 0.00~0.50%, Ce: 0.00~0.50%, B: 0.00~0.50%, Y: 0.00~0.50%, Sr: 0.00~0.50%, Total of Sb, Pb, Cu, Ti, Cr, Nb, Zr, Mn, Mo, Ag, Li, Bi, V, Co, In, W, P, La, Ce, B, Y, Sr: 0.00~5.00%, Remaining part: Zn and impurities.

[0062] Furthermore, the surface of the coating is made into an uneven surface. In the cross section of the coating, the relationship between the length Lo of the coating in the longitudinal direction in the observation area of ​​the cross section and the total length Lr of the outline of the surface of the coating in the observation area satisfies the following formula (1). The coating contains one or both of a plurality of blocky binary eutectic structures or a plurality of blocky ternary eutectic structures. At least a portion of the plurality of blocky binary eutectic structures or the plurality of blocky ternary eutectic structures are continuously present from the surface of the coating up to a position where the average thickness of the coating is 1 / 2.

[0063] Figure 1-2 The diagram shows a cross-sectional view of the plated steel 21. Figure 1-2 This is a schematic diagram illustrating the positional relationship between steel 11 and coating 12. It should be noted that... Figure 1-2 The unevenness of the surface of the coating 12 is omitted from the description.

[0064] like Figure 1-2As shown, the plated steel 21 in this embodiment includes steel 11. There are no particular limitations on the shape of the steel 11. Furthermore, there are no particular limitations on the material of the steel 11. Examples of steel 11 include steel materials standardized according to Japanese Industrial Standards (JIS) and used for general structural and mechanical structural purposes, such as carbon steel, alloy steel, and high-tensile steel. Specific examples of such steel materials include cold-rolled steel, hot-rolled steel, hot-rolled steel sheets for automotive structures, hot-rolled high-tensile steel sheets for automotive processing, cold-rolled steel sheets for automotive structures, cold-rolled high-tensile steel sheets for automotive processing, and high-tensile steel generally referred to as hot-stamped material that has been quenched during hot working. There are no particular limitations on the composition of such steel materials. The steel can also be steel formed by hot pressing or other processing of steel sheets.

[0065] Furthermore, the steel 11 constituting the plated steel 21 in this embodiment can also be high-tensile steel for automotive components.

[0066] The plated steel 21 according to this embodiment has a plating layer 12 disposed on at least a portion of the surface of the steel 11. Figure 1-2 In this process, the coating 12 is formed on one side of the steel 11, but the coating 12 can also be formed on both sides of the steel 11. It should be noted that the coating 12 is preferably a coating film manufactured by a so-called hot-dip galvanizing process.

[0067] The coating 12, due to its chemical composition described later, is mainly composed of a Zn-Al-Mg alloy layer. Furthermore, the coating 12 of the plated steel 21 according to this embodiment may also include an Fe-Al interface alloy layer with Fe and Al as main components between the steel 11 and the Zn-Al-Mg alloy layer. That is, the coating 12 can be a single-layer structure of the Zn-Al-Mg alloy layer, or a multilayer structure including both a Zn-Al-Mg alloy layer and an Fe-Al interface alloy layer.

[0068] The chemical composition of the coating is described below, but the percentage (%) for each element in the chemical composition refers to "mass %". The content of elements in the chemical composition is sometimes recorded as element concentration (e.g., Zn concentration, Mg concentration, etc.).

[0069] The term "adhesive layer adhesion" refers to the property that the adhesive layer is not easily peeled off from the coating when an adhesive layer is provided on the surface of the coating, or when a film portion is provided on the surface of the coating and then an adhesive layer is provided on the film portion.

[0070] In addition, "planar corrosion resistance" refers to the inherent resistance of the coating (specifically, the Zn-Al-Mg alloy layer) to corrosion.

[0071] Furthermore, "end-face corrosion resistance" refers to the property of inhibiting corrosion of steel at exposed parts of the steel (such as the cut end face of plated steel).

[0072] The coating described in this embodiment contains Zn and other alloying elements. The chemical composition of the coating will be described in detail below. It should be noted that elements with a concentration lower limit of 0.00% are not essential for solving the problems of the plated steel described in this embodiment, but are optional elements permitted to be included in the coating for purposes such as improving properties.

[0073] <Al:10.00~30.00%> Al contributes to improved surface corrosion resistance and processability. Therefore, the Al concentration is set to 10.00% or higher. On the other hand, in the case of excessive Al, the Mg and Zn concentrations decrease relatively, and the surface corrosion resistance deteriorates. Therefore, the Al concentration is set to 30.00% or lower. The Al concentration can also be set to 10.00–25.00% or 15.00–22.00%. The Al concentration can also be set to 11.00% or higher, 13.00% or higher, or 16.00% or higher. The Al concentration can also be set to 28.00% or lower, 24.00% or lower, or 20.00% or lower.

[0074] <Mg:1.00~15.00%> Mg is an essential element for ensuring planar corrosion resistance. Furthermore, it is necessary for the crystallization of binary eutectic structures, ternary eutectic structures, and the Mg₂Sn phase. Therefore, the Mg concentration is set to 1.00% or higher. On the other hand, if the Mg concentration is excessive, workability, especially pulverization, may deteriorate, thereby worsening planar corrosion resistance. Therefore, the Mg concentration is set to 15.00% or lower. The Mg concentration can also be set to 4.50–15.00% or 5.00–15.00%. The Mg concentration can also be set to 2.00% or higher, 3.00% or higher, or 4.00% or higher. Alternatively, the Mg concentration can be set to 13.00% or lower, 10.00% or lower, or 8.00% or lower.

[0075] The elements described below, except for Fe and Zn, are arbitrarily added elements, therefore their lower limit is set to above 0.00%.

[0076] <Sn:0~1.00%> The Sn concentration can also be 0.00%. On the other hand, Sn is an element that forms intermetallic compounds with Mg, thereby improving the planar corrosion resistance of the coating. Therefore, the Sn concentration can also be set to 0.05% or more, 0.10% or more, or 0.20% or more. However, if the Sn concentration is excessive, the planar corrosion resistance deteriorates. Therefore, the Sn concentration is set to 1.00% or less. The Sn concentration can also be set to 0.80% or less, 0.60% or less, 0.50% or less, 0.20% or less, or 0.06% or less.

[0077] <Si:0%~2.00%> The Si concentration can also be 0.00%. On the other hand, Si contributes to improved planar corrosion resistance. Furthermore, it is an essential element for the crystallization of the Mg₂Si phase. Therefore, the Si concentration can be set to more than 0.00%, 0.01%, 0.05%, or 0.10%. On the other hand, if the Si concentration is excessive, the planar corrosion resistance deteriorates. Therefore, the Si concentration is set to 2.00% or less. The Si concentration can also be set to 1.80%, 1.50%, 1.20%, or 1.00% or less.

[0078] <Ca:0%~2.00%> The Ca concentration can also be 0.00%. On the other hand, Ca is an element that can adjust the amount of Mg leaching optimally for imparting surface corrosion resistance. Therefore, the Ca concentration can also be 0.01% or more, or 0.02% or more. On the other hand, if the Ca concentration is excessive, the surface corrosion resistance and processability deteriorate. Therefore, the Ca concentration is set to 2.00% or less. The Ca concentration can also be set to 1.00% or less, 0.50% or less, 0.10% or less, or 0.05% or less.

[0079] <Ni:0~1.00%> The Ni concentration can also be 0.00%. On the other hand, Ni helps improve the corrosion resistance of the end face. Therefore, the Ni concentration can also be set to 0.001% or more. On the other hand, if the Ni concentration is excessive, the corrosion resistance of the plane will deteriorate. Therefore, the Ni concentration is set to 1.00% or less. The Ni concentration can also be set to 0.50% or less, 0.10% or less, or 0.01% or less.

[0080] <Fe:0.01%~15.00%> The concentration of Fe can also be 0.00%. However, since Fe sometimes mixes into the coating from the base metal steel, it can also contain 0.01% or more in the coating. It has been confirmed that if the Fe concentration is 15.00% or less, there is no adverse effect on the performance of the coating. The Fe concentration can also be set, for example, at 0.01% or more, 0.10% or more, or 0.50% or more. The Fe concentration is set at 15.00% or less. The Fe concentration can also be set at 10.00% or less, 5.00% or less, 2.00% or less, or 1.00% or less.

[0081] <Sb, Pb: 0 - 0.50% respectively> The concentrations of Sb and Pb can also be 0.00%. On the other hand, Sb and Pb contribute to the improvement of the end face corrosion resistance. Therefore, the concentration of each of Sb and Pb can also be set at 0.01% or more, 0.03% or more, or 0.05% or more. On the other hand, if the concentrations of Sb and Pb are excessive, the planar corrosion resistance deteriorates. Therefore, the concentration of each of Sb and Pb is set at 0.50% or less. The concentration of each of Sb and Pb can also be set at 0.40% or less, 0.20% or less, or 0.10% or less.

[0082] <Cu, Ti, Cr, Nb, Zr, Mn, Mo, Ag and Li: 0.00 - 1.00% respectively> The concentrations of Cu, Ti, Cr, Nb, Zr, Mn, Mo, Ag and Li can also be 0.00% respectively. On the other hand, they contribute to the improvement of the end face corrosion resistance. Therefore, the concentrations of these elements can also be set at 0.01% or more respectively. On the other hand, if the concentrations of these elements are excessive respectively, the planar corrosion resistance deteriorates. Therefore, the concentrations of these elements are set at 1.00% or less respectively. The concentrations of these elements can also be set at 0.50% or less, 0.10% or less, 0.05% or less, or 0.03% or less respectively.

[0083] <Bi, V, Co, In, W: 0.00 - 1.00% respectively> The concentrations of Bi, V, Co, In, and W can also be 0.00% respectively. On the other hand, these elements contribute to the improvement of the end face corrosion resistance respectively. Therefore, the concentrations of these elements can also be set at 0.001% or more or 0.01% or more respectively. On the other hand, if the concentrations of these elements are excessive, the planar corrosion resistance deteriorates. Therefore, the concentrations of Bi, V, Co, In, and W are set at 1.00% or less respectively. The concentrations of these elements can also be set at 0.50% or less, 0.10% or less, 0.02% or less, or 0.01% or less respectively.

[0084] <P: 0 - 1.00%> The concentration of P can also be 0.00%. On the other hand, P helps improve the corrosion resistance of the end face. Therefore, the concentration of P can also be set to 0.005% or more, or 0.01% or more. On the other hand, if the concentration of P is excessive, the planar corrosion resistance deteriorates. Therefore, the concentration of P is set to 1.00% or less. The concentration of P can also be set to 0.05% or less, 0.03% or less, or 0.01% or less.

[0085] <B, Y, and Sr: 0 to 0.50% respectively> The concentration of each of B, Y, and Sr can also be 0%. On the other hand, B, Y, and Sr help improve the corrosion resistance of the end face. Therefore, the concentration of these elements can also be set to 0.001% or more, or 0.01% or more. On the other hand, if the concentration of B, Y, and Sr is excessive, the planar corrosion resistance deteriorates. Therefore, the concentration of these elements is set to 0.50% or less. The concentration of these elements can also be set to 0.10% or less, 0.02% or less, or 0.01% or less.

[0086] <La, Ce: 0.00 to 0.50% respectively> The concentration of La and Ce can also be 0.00%. On the other hand, La and Ce help improve the corrosion resistance of the end face. Therefore, the concentration of these elements can also be set to 0.01% or more. On the other hand, if the concentration of La and Ce is excessive, the planar corrosion resistance deteriorates. Therefore, the concentration of these elements is set to 0.50% or less. The concentration of these elements can also be set to 0.10% or less, 0.05% or less, or 0.02% or less. In addition, the total amount of La and Ce can be set to 0.05 to 0.50%.

[0087] <Total of Sb, Pb, Cu, Ti, Cr, Nb, Zr, Mn, Mo, Ag, Li, Bi, V, Co, In, W, P, La, Ce, B, Y, Sr: 0.00 to 5.00%> The total of these elements is set to 0.00 to 5.00%. If the total exceeds 5.00%, sometimes the planar corrosion resistance or the end-face corrosion resistance decreases.

[0088] <The remainder: Zn and impurities> The remainder of the composition of the coating according to this embodiment is Zn and impurities. Zn is an element that gives the coating planar corrosion resistance and end-face corrosion resistance. Impurities refer to components contained in the raw materials, or components mixed in during the manufacturing process, and are not intentionally contained components. For example, in the coating, due to the mutual atomic diffusion between the base steel and the plating bath, sometimes components other than Fe are also slightly mixed in as impurities.

[0089] Furthermore, in the coating involved in this embodiment, the total content of Al, Mg and Zn is preferably 74.00% or more, or it may be 80.00% or more, or it may be 90.00% or more, or it may be 95.00% or more, or it may be 98.00% or more.

[0090] The chemical composition of the coating was determined using the following method. First, the coating was peeled and dissolved using an acid containing an inhibitor that suppresses corrosion of the steel to obtain an acid solution. Next, the obtained acid solution was subjected to ICP analysis. This allowed the determination of the chemical composition of the coating. There are no particular restrictions on the type of acid used, as long as it is capable of dissolving the coating. It should be noted that the chemical composition determined by the above method is the average chemical composition of the entire coating.

[0091] <Surface of the coating> The surface of the coating in this embodiment is made into an uneven surface. The roughness of the uneven surface is expressed by the relationship between Lo and Lr, as shown in the following formula (1). That is, (Lr-Lo) / Lo×100 must be 2.0 (%) or more. When (Lr-Lo) / Lo×100 is less than 2.0 (%), the roughness of the uneven surface is small, and the adhesion of the adhesive layer cannot be improved. (Lr-Lo) / Lo×100 is more preferably satisfied by the following formula (2), and even more preferably satisfied by the following formula (3). There is no particular need for an upper limit to (Lr-Lo) / Lo×100. If it is too large, the surface smoothness of the coating may decrease, and the average thickness of the adhesive layer may become uneven, resulting in insufficient adhesion performance. Therefore, it can be 40 (%) or less, 20 (%) or less, or 12 (%) or less.

[0092] (Lr-Lo) / Lo×100≥2.0 (%) (1) (Lr-Lo) / Lo×100≥6.0 (%) (2) (Lr-Lo) / Lo×100≥8.0 (%) (3) It should be noted that in equations (1) to (3), the length Lo is the length of the coating along its length direction within the observation area of ​​the cross-section of the coating, and Lr is the total length of the surface contour line of the coating within the observation area. The observation area refers to the field of view when observing the cross-section of the coating with a scanning electron microscope. The length of the coating along its length direction within this field of view is Lo, and the total length of the surface contour line of the coating corresponding to the length Lo along its length direction is Lr. When measuring Lo and Lr, it is preferable to set the field of view for observation with a scanning electron microscope so that the length Lo along the length direction of the coating is 500 μm. Alternatively, multiple field of view can be combined to synthesize a field of view where the length Lo along the length direction of the coating is 500 μm.

[0093] The observation field of view is positioned at a distance of 5 mm or more from the end of the coated steel. If a weld is present on the coated steel, the observation field of view is positioned at a distance of 1 mm or more from the weld bead. Furthermore, if the coated steel has a bent portion, the observation field of view is positioned at a distance of 2 mm or more from the bent portion. This excludes the influence of cutting, welding, and bending processes on the surface properties of the coating from the measurement results.

[0094] The field of view is preferably positioned on a flat area. However, there are cases where the coated steel does not have flat areas. For example, when the coated steel is used as an exterior component of an automobile, it may have a generally gently curved shape and lack flat areas. In such cases, the field of view is preferably positioned in an area with a radius of curvature of 5 mm or more.

[0095] The number of observation fields is set to 5. First, calculate (Lr-Lo) / Lo×100 for each of the 5 observation fields, and then calculate the arithmetic mean of these values. This arithmetic mean is taken as (Lr-Lo) / Lo×100 for the coated steel.

[0096] Figure 1-3 An example of the field of view when observing with a scanning electron microscope is illustrated in the diagram. Figure 1-3 The diagram shows the relationship between Lo and Lr. Figure 1-3 In the diagram, symbol 11 represents steel, symbol 12 represents the coating, and symbol 13 represents the interface alloy layer. The two arrows on symbols Lo and Lr schematically represent the lengths of Lo and Lr, respectively. Furthermore, in... Figure 1-3 In the diagram, the uneven surface of the coating is schematically represented.

[0097] <Coating Structure> In the coating of this embodiment, there are one or both of the following: multiple blocky binary eutectic structures or multiple blocky ternary eutectic structures. The binary eutectic structure is a eutectic structure of η-Zn phase and Al-Zn phase, and the ternary eutectic structure is a eutectic structure of Al phase, Zn phase, and MgZn2 phase. These eutectic structures can also be eutectic structures in which the phases constituting the eutectic structure are aggregated in a lamellar manner. That is, the binary eutectic structure can also have a lamellar structure formed by the overlapping of layered η-Zn phase and layered Al-Zn phase. The ternary eutectic structure can also have a lamellar structure formed by the overlapping of layered Al phase, layered Zn phase, and layered MgZn2 phase.

[0098] In addition to these eutectic structures, the coating also contains blocky Al phases, Al-Zn phases, Zn phases, MgZn2 phases, etc. Furthermore, a eutectoid structure sometimes forms in the coating, containing layered Zn and layered Al phases. Although this eutectoid structure has a lamellar structure, it does not conform to a binary or ternary eutectic structure.

[0099] In the coating of this embodiment, at least a portion of multiple blocky binary or ternary eutectic structures continuously exist from the surface of the coating up to a position half the average thickness of the coating. At least a portion of these blocky binary or ternary eutectic structures are exposed on the surface of the coating. Compared to other phases such as Al and Al-Zn, the binary or ternary eutectic structures exhibit superior adhesion to the adhesive layer. Therefore, by exposing the binary or ternary eutectic structures on the surface of the coating, the overall adhesion of the coating to the adhesive layer is improved.

[0100] Furthermore, when cracks occur in the coating during the processing of the coated steel, these cracks mostly propagate along the boundary between the binary or ternary eutectic structure and other phases / structures. In this embodiment, at least a portion of the binary or ternary eutectic structure continuously exists up to half the average thickness of the coating. Therefore, cracks generated during bending processes propagate from the surface of the coating towards the steel, becoming less likely to propagate in a direction parallel to the surface of the coating. Thus, even if cracks occur, the eutectic structure becomes less likely to detach from the coating, suppressing powdering or peeling. Consequently, even if the coating is processed, the coating adhesion is not reduced.

[0101] For the coating of this embodiment, it is more preferable that at least a portion of the plurality of blocky binary or ternary eutectic structures continuously exist from the surface of the coating to the Fe-Al interface alloy layer. This further suppresses powdering or peeling, and further improves the adhesion of the coating to the adhesive layer.

[0102] Figure 1-4 An enlarged schematic diagram showing an example of the coating of this embodiment is provided. Figure 1-4 The diagram schematically represents the uneven surface of the coating and illustrates the presence of binary or ternary eutectic structures. The shaded areas in the diagram represent binary or ternary eutectic structures. Figure 1-4 In the symbol 11, steel is represented; 12, coating is represented; 13, interface alloy layer is represented; and 14, binary eutectic structure or ternary eutectic structure is represented.

[0103] like Figure 1-4 As shown, the binary or ternary eutectic structure 14 is known to be continuous from the surface of the coating 12 toward the steel 11 side. Furthermore, the binary or ternary eutectic structure 14 is known to be continuously present up to the Fe-Al interface alloy layer 13 of the coating 12 on the steel side. It should be noted that... Figure 1-4The example shown is a binary or ternary eutectic structure 14 that extends mostly to the Fe-Al interface alloy layer 13 on the steel 11 side of the coating 12. However, this embodiment is not limited to this and may also include a binary or ternary eutectic structure 14 that extends to half the position of the coating 12.

[0104] For reference, a cross-sectional schematic diagram of a previous coating is shown below. Figure 1-5 In the past, the coating surface of the coating 112 was flat, and the binary eutectic structure or ternary eutectic structure 114 was distributed near the interface alloy layer 113 of the coating 112 or near the surface of the coating. The binary eutectic structure or ternary eutectic structure 114 that continued to 1 / 2 position of the coating 112 was not visible.

[0105] Furthermore, the surface of the plating layer 12 in this embodiment is as follows: Figure 1-3 , Figure 1-4 As illustrated, the surface is uneven, and a binary or ternary eutectic structure 14 continuously exists to a depth of 1 / 2 the average thickness of the coating 12. Figure 1-4 As shown, it is more prevalent in the recesses of the uneven surface. This will be described below because a binary or ternary eutectic structure crystallizes during the latter half of the coating's solidification process. The concentration of the binary or ternary eutectic structure in the recesses, combined with the effect of the uneven surface shape, improves coating adhesion.

[0106] Furthermore, in this embodiment, the binary or ternary eutectic structure that continuously exists from the surface of the coating to the Fe-Al interface alloy layer can also be more abundant in the recesses of the uneven surface.

[0107] As described below in the manufacturing method description, binary or ternary eutectic structures begin to crystallize after the Al and Al-Zn phases crystallize. It is believed that the crystallization of these eutectic structures begins with nucleation in the steel-side region of the coating, more specifically, on the surface of the Fe-Al interface alloy layer. Furthermore, it is believed that the crystallization of the eutectic structure proceeds towards the surface of the coating. Therefore, it is believed that the binary or ternary eutectic structures involved in this embodiment are mostly continuous from the surface of the coating to the Fe-Al interface alloy layer.

[0108] However, when the internal structure of the coating is observed in any cross section, it is not limited to binary or ternary eutectic structures; it is always observed as a continuous morphology from the surface of the coating to the Fe-Al interface alloy layer. This is because the shapes of the bulk binary or ternary eutectic structures are amorphous, and therefore, the morphology of the binary or ternary eutectic structures appears different depending on the location of the cross section.

[0109] The inventors conducted research and found that if at least a portion of multiple blocky binary or ternary eutectic structures are observed to exist continuously from the surface of the coating up to half the average thickness of the coating in at least the cross-section of the coating, it is highly likely that the binary or ternary eutectic structures exist in a continuous form from the surface of the coating up to the Fe-Al interface alloy layer, and it is speculated that this improves the coating adhesion.

[0110] In this embodiment, the number of portions in which the binary or ternary eutectic structure continuously exists from the surface of the coating up to half the average thickness of the coating is preferably 1 to 15 portions in a rectangular region of 500 μm on the long side and 150 μm on the short side of the coating surface. If the number of portions is less than one, the coating adhesion becomes insufficient, which is therefore undesirable. Furthermore, when formula (2) above is true, the number of these portions is preferably 3 to 15. Moreover, when formula (3) above is true, the number of these portions is preferably 5 to 15.

[0111] The existence of a binary or ternary eutectic structure is confirmed as follows.

[0112] A rectangular region with a long side of 500 μm and a short side of 150 μm is defined on the surface of the coating. The position of this region is determined using the same method as the observation field described above for evaluating the roughness of the uneven surface of the coating.

[0113] Within this area, the number and location of binary or ternary eutectic structures exposed on the surface of the coating are identified. Next, the surface of the coating containing this area is sequentially ground to depths of 1 / 4, 1 / 2, 3 / 4, and 9 / 10 of the average thickness of the coating, and then mirror-polished to create observation surfaces. Then, at the 1 / 4, 1 / 2, 3 / 4, and 9 / 10 depths, the number and location of binary or ternary eutectic structures in the observation surfaces at each depth are identified. Then, at all locations on the surface of the coating, at the 1 / 4 and 1 / 2 depths, the number of binary or ternary eutectic structures appearing at the same location is counted. Regarding whether a structure appears at the same location, any eutectic structure located on the surface of the coating within a projection range of 15 μm radius from the centroid of the eutectic structure can be considered to appear at the same location. Binary or ternary eutectic structures appearing at the same location are defined as those that continuously exist from the surface of the coating up to half the average thickness of the coating. There are no particular restrictions on the grinding process, but examples include precision machining such as lapping and focused ion beam (FIB) machining.

[0114] Furthermore, the presence of binary or ternary eutectic structures at the same locations was confirmed at all depths: the surface of the coating, 1 / 4 depth, 1 / 2 depth, 3 / 4 depth, and 9 / 10 depth. As a result, it was determined that the binary or ternary eutectic structures at the same locations are continuously present from the surface of the coating to the Fe-Al interfacial alloy layer.

[0115] It should be noted that the average thickness of the coating is set as the average thickness of the coating in a rectangular area with a long side of 500 μm and a short side of 150 μm.

[0116] Furthermore, the average surface position of the coating is estimated from the position of the interface between the steel and the coating, which is equivalent to the height of the average thickness of the coating. Using the estimated surface position as a reference, the depths at 1 / 4, 1 / 2, 3 / 4, and 9 / 10 of the average thickness of the coating are determined.

[0117] Furthermore, regarding the confirmation of the existence of binary or ternary eutectic structures, if there are parts in the bonded structure that are not bonded to the plated steel and have exposed plating, then cut out such parts and make a sample for confirmation.

[0118] In addition, when the entire surface of the steel plated in the adhesive bonding structure is bonded, the bonded part can be carefully separated to expose the plating, and the part can be cut out to make a sample for confirmation.

[0119] When the coating contains 0.05% to 0.5% Sn, it is preferable to include the Mg2Sn phase in the coating. Since the Mg2Sn phase is present in small amounts, its presence can be detected and confirmed by X-ray diffraction using the θ-2θ method. The presence of the Mg2Sn phase in the coating further improves the corrosion resistance of the coating's end face. The X-ray diffraction determination of the Mg2Sn phase can be performed using the θ-2θ method.

[0120] The adhesion amount on each side of the coating is set to, for example, 20-200 g / m². 2 Within the specified range. This can be achieved by setting the adhesion amount on each side to 20g / m². 2 The above methods can further improve the surface corrosion resistance and end-face corrosion resistance of coated steel. On the other hand, by setting the adhesion amount on each side to 200g / m²... 2 The following steps can further improve the processability of coated steel.

[0121] "Skin Part 22" Next, the membrane portion 22 will be described.

[0122] The plated steel 21 described in this embodiment may also have a film portion 22 disposed on at least a portion of the plating. Hereinafter, refer to... Figure 2-1 and Figure 2-2 The membrane portion 22 will be described.

[0123] Figure 2-1 yes Figure 1-1 The enlarged schematic diagram of the bonding area of ​​the adhesive bonding structure shown is a schematic diagram used to illustrate the positional relationship of the film portion 22, the adhesive layer 4, the first component 2 and the second component 3, and the organic compound phase contained in the film portion 22.

[0124] Figure 2-1 The diagram shows a state in which a film portion 22 is formed on at least a portion of the surface of the coating on the plated steel 21. At least a portion of the film portion 22 is in contact with the adhesive layer 4, and the first member 2 is bonded to the second member 3 via the film portion 22 and the adhesive layer 4. The film portion 22 contains at least one organic resin phase comprising urethane groups, epoxy groups, and ester groups, and an organic compound phase formed from an organosilicon compound. The organosilicon compound of this embodiment contains Si-C bonds. Furthermore, the organosilicon compound of this embodiment contains at least one of Si-O bonds or Si-OH bonds. That is, the organosilicon compound of this embodiment contains at least one of Si-C bonds and Si-O bonds or Si-OH bonds. The structure of the film portion 22 will be described in detail below.

[0125] The film portion 22 involved in this embodiment, as described above, contains an organic resin phase comprising one or more of urethane groups, epoxy groups, and ester groups, and an organic compound phase formed from an organosilicon compound. More specifically, as... Figure 2-1 As schematically illustrated, in the film portion 22, the organic resin phase having the aforementioned specific functional groups mainly exists as resin particles 221, and has a structure in which the resin particles 221 are dispersed in an organic compound phase 223 formed of an organosilicon compound. It should be noted that the second component 3, for example, has a plated steel 31 and a film portion 32, in which, similarly to the film portion 22, resin particles 321 are dispersed in the organic compound phase 323.

[0126] By having an organic compound phase 223 formed from an organosilicon compound in the film portion 22, chemical bonds such as Si-O-Me bonds are formed between the elements of the coating layer 12 constituting the plated steel 21 and the film portion 22. Here, Me is a metallic element that is the main component of the coating layer 12, namely Zn, Al, Mg, or Fe. By forming such a primary bond, the bonding state between the coating layer 12 of the plated steel 21 and the film portion 22 becomes stronger, and the adhesion between the coating layer 12 and the film portion 22 is further improved. As a result, a state in which water is not easily penetrated from the outside into the interface between the coating layer 12 and the film portion 22 can be achieved. Thus, in the adhesive bonding structure 1 according to this embodiment, the adhesion durability between the plated steel 21 and the adhesive layer 4 can be improved.

[0127] In the film portion 22, the total volume ratio of the organic compound phase 223 and the inorganic compound phase relative to the total volume of the film portion 22 is preferably 16 vol% to 84 vol%. If the total volume ratio of the organic compound phase 223 and the inorganic compound phase relative to the total volume of the film portion 22 is 16 vol% or more, Si-O-Me bonds are sufficiently formed. If the total volume ratio of the organic compound phase 223 and the inorganic compound phase relative to the total volume of the film portion 22 is 84 vol% or less, the adhesion between the adhesive layer 4 and the film portion 22 is further improved. The total volume ratio of the organic compound phase 223 and the inorganic compound phase is preferably 20 vol% or more, more preferably 30 vol% or more. The total volume ratio of the organic compound phase 223 and the inorganic compound phase is preferably 80 vol% or less, more preferably 70 vol% or less. When determining the total volume ratio of the organic compound phase 223 and the inorganic compound phase based on the cross-section of the membrane portion 22, the ratio of the total area of ​​the organic compound phase 223 and the inorganic compound phase to the cross-sectional area of ​​the membrane portion 22 is determined as the total volume ratio of the organic compound phase 223 and the inorganic compound phase.

[0128] In the film portion 22, the volume percentage of the organic compound phase 223 relative to the total volume of the film portion 22 is preferably 16 vol% to 84 vol%. If the volume percentage of the organic compound phase 223 relative to the total volume of the film portion 22 is 16 vol% or more, Si-O-Me bonds are sufficiently formed. If the volume percentage of the organic compound phase 223 relative to the total volume of the film portion 22 is 84 vol% or less, the adhesion between the adhesive layer 4 and the film portion 22 is further improved. The volume percentage of the organic compound phase 223 is preferably 20 vol% or more, more preferably 30 vol%. The volume percentage of the organic compound phase 223 is preferably 80 vol% or less, more preferably 70 vol%. When determining the volume percentage of the organic compound phase 223 based on the cross-section of the film portion 22, the volume percentage of the organic compound phase 223 is determined as the ratio of the area of ​​the organic compound phase 223 to the cross-sectional area of ​​the film portion 22.

[0129] The coating portion 22 may also contain an inorganic compound phase formed from inorganic silicon compounds. The volume percentage of the inorganic compound phase relative to the total volume of the coating portion 22 can be set to 10 vol% or less. If the volume percentage of the inorganic compound phase is 10 vol% or less, the adhesion between the metal portion 21 and the coating portion 22 is further improved. The coating portion 22 may also not contain an inorganic compound phase, therefore its lower limit is 0 vol%. When the coating portion 22 contains an inorganic compound, the adhesive strength is improved because the strength of the coating portion 22 is increased. Examples of inorganic silicon compounds constituting the inorganic compound phase include colloidal silica and fumed silica. When determining the volume percentage of the inorganic compound phase from the cross-section of the coating portion, the volume percentage of the inorganic compound phase is determined by the ratio of the area of ​​the inorganic compound phase to the cross-sectional area of ​​the coating portion 22. For inorganic silicon compounds, elemental analysis is performed in the cross-section of the coating portion using an electron probe microanalysis (EPMA) to determine the volume percentage from its constituent elements. The volume ratio of inorganic silicon compounds and organosilicon compounds was determined by observing their cross-sections using a scanning electron microscope (SEM) after elemental analysis, and the results were used to make the judgment.

[0130] Furthermore, in the film portion 22, resin particles 221 are dispersed in the organic compound phase 223, but the resin particles 221 have one or more functional groups selected from urethane groups, epoxy groups, and ester groups. These functional groups are also abundant in the resin constituting the adhesive. Therefore, by including resin particles 221 with such functional groups in the film portion 22, the adhesion at the interface between the film portion 22 and the adhesive layer 4 is improved. As a result, water can be prevented from easily penetrating into the interface between the film portion 22 and the adhesive layer 4. Thus, in the adhesive bonding structure 1 according to this embodiment, the adhesion durability between the film portion 22 and the adhesive layer 4 can be improved.

[0131] As explained above, by including an organic resin phase and an organic compound phase 223 in the film portion 22, the adhesion of the two interfaces in the film portion 22 (the interface between the film portion 22 and the metal portion 21, and the interface between the film portion 22 and the adhesive layer 4) is improved, thereby enhancing the adhesion durability of the adhesive bonding structure 1.

[0132] Here, the resin particles 221 constituting the organic resin phase described above are not particularly limited as long as they are resin particles having one or more functional groups selected from urethane groups, epoxy groups, and ester groups. The resin particles 221 can be either a water-dispersible aqueous resin dispersed in water or a solvent-based resin dispersed in an organic solvent, but from the perspective of manufacturing cost and environmental adaptability, an aqueous resin is preferred. The resin constituting the resin particles 221 is preferably a resin having a main framework containing carbon atoms.

[0133] Examples of water-based resins include urethane resins, epoxy resins, polyester resins, and mixtures of two or more of these resins. When using polyester resins, the molecular weight is preferably between 10,000 and 30,000. If the molecular weight is below 10,000, it can be difficult to ensure sufficient processability. On the other hand, if the molecular weight exceeds 30,000, the number of bonding sites on the resin itself decreases, making it difficult to ensure excellent adhesion to the adhesive layer 4. Furthermore, when using a curing agent such as melamine for crosslinking, the crosslinking reaction may not proceed sufficiently, resulting in reduced performance of the film portion 22. In the case of urethane resins, the morphology of the urethane resin is preferably an emulsion with a particle size of 10 to 100 nm (preferably 20 to 60 nm). Too small a particle size can sometimes lead to higher costs. On the other hand, too large a particle size increases the gaps between the emulsions during coating, thus sometimes reducing the barrier properties of the film portion 22. Types of urethane resins include ether-based, polycarbonate-based, and ester-based resins. They can be used alone or in combination.

[0134] On the other hand, examples of solvent-based resins include polyester resins, urethane resins, epoxy resins, and mixtures of two or more of these resins.

[0135] Here, the resin contained in the film portion 22 can be a cross-linked resin with a cross-linking structure or a non-cross-linked resin without a cross-linking structure. As a cross-linking agent (curing agent) for imparting a cross-linking structure to the resin, melamine, isocyanate, silane compound, zirconium compound, titanium compound, etc. are preferred.

[0136] The amount of crosslinking agent added relative to 100 parts by weight of the resin solids is preferably 5 to 30 parts by weight. If the amount of crosslinking agent added is less than 5 parts by weight, the crosslinking reaction with the resin may decrease, resulting in insufficient performance as a coating film. On the other hand, if the amount of crosslinking agent added exceeds 30 parts by weight, the crosslinking reaction may over-progress, causing the film portion 22 to become excessively hard and reducing processability. Furthermore, when using silane compounds, zirconium compounds, or titanium compounds as crosslinking agents, if the amount of crosslinking agent added exceeds 30 parts by weight, the stability of the coating may further decrease, which is therefore not preferred.

[0137] The shape of the resin particles 221 is not particularly limited. For example, it can be spherical, quasi-spherical (e.g., ellipsoidal, egg-shaped, rugby ball-shaped, etc.), or polyhedral (e.g., soccer ball-shaped, dice-shaped, brilliant cut of various gemstones, etc.), elongated (e.g., rod-shaped, needle-shaped, fibrous, etc.), or planar (e.g., scale-shaped, plate-shaped, flake-shaped, etc.).

[0138] In the film portion 22 according to this embodiment, the average particle size of the resin particles 221 is preferably 20 nm or more. By having an average particle size of 20 nm or more, the affinity with the adhesive layer 4 described above can be more reliably improved, which is therefore preferable. The average particle size of the resin particles 221 is more preferably 30 nm or more, and even more preferably 50 nm or more. On the other hand, if the average particle size of the resin particles 221 becomes less than 200 nm, a denser resin barrier layer can be formed, which can further improve the adhesion between the film portion 22 and the adhesive layer 4, which is therefore preferable. The average particle size of the resin particles 221 is more preferably 180 nm or less, and even more preferably 150 nm or less.

[0139] Here, the "average particle size" of the resin particles 221 refers to the average first-order particle size when the resin particles 221 exist alone in the film portion 22, and to the average second-order particle size when the resin particles 221 are aggregated together. The average particle size of the resin particles 221 is preferably determined by the following measurement method.

[0140] First, the portion of the adhesive bonding structure 1 containing the film portion 22 is cut off to expose its cross-section. This cross-section is then further ground to obtain a cross-sectional sample of the film portion 22 of the first component 2 in the thickness direction. Next, the film portion 22 of the cross-sectional sample is observed using a scanning electron microscope to obtain an observation image of the cross-section of the film portion 22. Ten resin particles 221 are randomly selected from the field of view of this observation image, and the area equivalent circle diameter of each resin particle 221 is measured. The area equivalent circle diameter of the resin particle 221 is set to be the average of the ten resin particles 221.

[0141] Here, whether the film portion 22 involved in this embodiment has at least one of urethane groups, epoxy groups, and ester groups can be determined by the following method. Similarly, whether it contains at least one of Si-C bonds, Si-O bonds, or Si-OH bonds can also be determined by the following method.

[0142] First, the portion of the adhesive bonding structure 1 with the film portion 22 is cut at an angle to expose its cross-section. This cross-section is then further ground to obtain a cross-sectional sample of the film portion 22 in the thickness direction of the first component 2. Next, the film portion 22 of the cross-sectional sample is analyzed using a micro-IR spectroscopy device. The determination is based on whether vibrational peaks originating from urethane groups, epoxy groups, ester groups, Si-O bonds, Si-C bonds, and Si-OH bonds are observed in the infrared absorption spectrum of the obtained film portion 22. Specifically, in the obtained infrared absorption spectrum, at 910 cm⁻¹... -1 If a peak is observed nearby, it is determined to contain epoxy groups, at 1550 cm⁻¹. -1 Nearby and 1740cm -1 If a peak is observed nearby, it is determined to contain carbamate groups, and the peak is located at 1720–1740 cm⁻¹. -1 If a peak is observed nearby, it is determined to contain an ester group. (1250–1260 cm⁻¹) -1 If a peak is observed nearby, it is determined to contain Si-C bonds, and the peak is located in the range of 1000–1100 cm⁻¹. -1 If a peak is observed nearby, it is determined to contain Si-O bonds, located at 3650-3690 cm⁻¹. -1 If a peak is observed nearby, it is determined to contain Si-OH bonds. It should be noted that as long as the film portion 22 can be sufficiently magnified, the cutting angle during tilting cuts can be arbitrary.

[0143] Furthermore, the cross-section along the thickness direction of the film portion 22 involved in this embodiment (e.g.) Figure 3In the cross-section shown, the area ratio of resin particles 221 preferably accounts for 16% or more of the cross-sectional area of ​​the film portion 22. That is, in the above cross-section, the area ratio of resin particles 221 relative to the cross-sectional area of ​​the film portion 22 is preferably 16% or more. By having the area ratio of resin particles 221 be 16% or more, the affinity with the adhesive layer 4 as described above can be improved more reliably. The area ratio of resin particles 221 in the cross-section of the film portion 22 is more preferably 30% or more, and even more preferably 40% or more. On the other hand, by having the area ratio of resin particles 221 in the cross-section be 84% or less, the adhesion between the film portion 22 and the metal portion 21 can be reliably maintained, and the affinity between the film portion 22 and the adhesive layer 4 can be further improved. The area ratio of resin particles 221 in the cross-section of the film portion 22 is more preferably 80% or less, and even more preferably 70% or less.

[0144] The area ratio of resin particles 221 in the cross-section of the film portion 22 is preferably determined by the following measurement method. First, the portion of the adhesive bonding structure 1 in which the film portion 22 is disposed is cut off to expose the cross-section, and the cross-section is further ground to obtain a cross-sectional sample of the film portion 22 of the first component 2 in the thickness direction. Next, a portion of the film portion 22 of the cross-sectional sample is used to prepare a thin film sample for TEM observation using the FIB-micro sampling method and the low-temperature FIB-micro sampling method. The obtained thin film sample for TEM observation is observed using an FE-TEM capable of analyzing small areas. Five portions obtained by dividing the film portion 22 of the cross-sectional sample into five equal parts along the width direction are observed. At each observation portion, EDS analysis (elemental mapping) is performed on the cross-section near the interface between the metal part and the adhesive layer to obtain the elemental distribution maps of C, O, and Si. Then, the obtained elemental distribution maps are binarized for C and the other elements, and the average particle size and area ratio of the resin particles in the film portion are calculated.

[0145] Furthermore, the organic compound phase 223 involved in this embodiment is not particularly limited as long as it is an organosilicon compound containing at least one of Si-C bonds and Si-O bonds or Si-OH bonds. For example, organosilicon compounds having epoxy propoxy or mercapto groups are preferred. As organosilicon compounds, by using organosilicon compounds having epoxy propoxy or mercapto groups, the Si-O-Me bond formation state as detailed below can be achieved more reliably and in a more preferred state, and long-term adhesive durability can be achieved more reliably. It should be noted that, in addition to organosilicon compounds having epoxy propoxy or mercapto groups, organosilicon compounds having amino, vinyl, or methacryloyl groups may also be present. However, the verification results obtained by the inventors have made it clear that when organosilicon compounds having amino, vinyl, or methacryloyl groups are used, the reaction between the organosilicon compound inside the film portion 22 and the resin constituting the organic resin phase is further promoted compared to the reaction at the interface between the metal portion 21 and the film portion 22, making it difficult to obtain long-term adhesive durability. Therefore, from the viewpoint of achieving long-term adhesive durability by preventing the penetration of electrolytes such as water, organosilicon compounds having epoxy propoxy or mercapto groups are preferred. It should be noted that commercially available organosilicon compounds with the same conditions can be used as organosilicon compounds having epoxy propoxy or mercapto groups, or organosilicon compounds prepared through organic synthesis can be used.

[0146] Here, in the coating portion 22 according to this embodiment, it is preferable that when Ar sputtering is performed on the coating portion 22 from the adhesive layer 4 side toward the coating layer 12 side at any location of the interface between the coating layer 12 including the plated steel 21 and the coating portion 22, and analysis is performed by time-of-flight secondary ion mass spectrometry (TOF-SIMS), the following analytical results can be obtained. That is, in the TOF-SIMS analysis results, it is preferable to observe a peak corresponding to the Si-O-Me bond (Me: Zn, Al, Mg, Fe constituting the coating layer 12), and the count value of the peak representing the Si-O-Me bond is 15 or more.

[0147] Furthermore, the Intensity (au), measured by the Total ion correction value (the value obtained by dividing the peak count of Si-O-Me bonds by the sum of all two detected ion counts), is preferably 1.0 × 10⁻⁶. -3 That's all. Specifically, the value obtained by dividing the peak count representing the Si-O-Me bond by the sum of all two ion counts detected within the mass scan range m / z = 0 to 300 (Total Ion correction value) is preferably 1.0 × 10⁻⁶. -3 above.

[0148] Here, the peaks corresponding to the Si-O-Me bonds are observed at characteristic positions for each type of element Me, depending on the specific element Me. For example, in the case of Me=Fe, the representative peak corresponding to the Si-O-Fe bond is observed at a mass (m / z) of 100±0.1 in the TOF-SIMS analysis results; in the case of Me=Zn, the representative peak corresponding to the Si-O-Zn bond is observed at a mass (m / z) of 108±0.1 in the TOF-SIMS analysis results; in the case of Me=Al, the representative peak corresponding to the Si-O-Al bond is observed at a mass (m / z) of 71±0.1 in the TOF-SIMS analysis results; and in the case of Me=Mg, the representative peak corresponding to the Si-O-Mg bond is observed at a mass (m / z) of 68±0.1 in the TOF-SIMS analysis results.

[0149] The analysis results indicate that the Si-O-Me bond formation reaction effectively occurs at the interface between the coating 12 and the film portion 22, resulting in the formation of a certain amount of Si-O-Me bonds at the interface. By forming a certain amount of Si-O-Me bonds at the interface between the coating 12 and the film portion 22, even when the bonded structure 1 is exposed to a humid environment, water penetration into the interface between the coated steel 21 and the film portion 22 can be prevented, thus maintaining longer-term adhesive durability.

[0150] The count value representing Si-O-Me bonds, as described above, is more preferably 20 or more, and even more preferably 30. The TotalIon correction value is more preferably 1.3 × 10⁻⁶. -3 The above is further preferred to be 2.0×10 -3 .

[0151] It should be noted that the count values ​​of the peaks corresponding to Si-O-Me bonds at the interface between the coating 12 and the film portion 22, as described above, can be determined as follows. First, by using a tilting cutting device (SAICAS) at a 5-degree angle to cut the adhesive joint between the coating 12 and the film portion 22 from the adhesive layer 4 side toward the coating 12 side, and then sputtering with Ar, a sample with the adhesive layer thickness reduced to approximately 1 μm is prepared. The portion with the adhesive layer thickness reduced to approximately 1 μm is analyzed by TOF-SIMS while sputtering with Ar from the adhesive layer side toward the coating 12 side. TOF-SIMS measurement is performed after sputtering Ar ion beam to a certain depth from the surface, and then the same Ar sputtering and TOF-SIMS measurement is performed. This process is repeated to obtain the depth direction distribution for various elements and bonds. The primary ion species is set to Au3. + The accelerating voltage was set to 30kV, the sputtering rate was set to approximately 80nm / min (SiO2 conversion), and the measurement area was set to 50μm×50μm.

[0152] For each ion, since a specific mass number exists, the depth-direction distribution map of the theoretical mass number of the target Si-O-Me bond is measured in the above-described TOF-SIMS measurement. Using the depth-direction distribution map of the mass corresponding to the Si-O-Me bond, and the respective depth-direction distribution maps of Me ions (the main component of the metal part) and C ions (the main component of the resin), the region from the rising portion of the Me ion count and the falling portion of the C ion count to the point where the C ion count becomes approximately constant is considered the interface region, and the count value corresponding to the Si-O-Me bond in this interface region is measured.

[0153] It should be noted that the area ratio of the resin particles 221 and the count of Si-O-Me bonds in TOF-SIMS can be appropriately adjusted during the formation of the film portion 22 according to this embodiment by selecting and adjusting the raw materials for the organic resin phase and the raw materials for the organic compound phase 223, respectively, and the surface state of the coating 12 can be appropriately controlled within the desired range.

[0154] Other Ingredients In addition to the components described above, the coating portion 22 may also contain other additives. Examples of such additives include oxide particles, extender pigments, solid lubricants, rust inhibitors, leveling agents, viscosity enhancers, pigment settling inhibitors, defoamers, and other well-known additives.

[0155] Average thickness of the membrane portion 22 In this embodiment, the average thickness of the film portion 22 as described above is preferably 0.2 μm or more on each side of the first member 2 (in other words, on each side of the plated steel 21). By setting the average thickness of each side of the film portion 22 to 0.2 μm or more, the effects described above caused by providing the film portion 22 can be exhibited more reliably. The average thickness of each side of the film portion 22 is more preferably 0.4 μm or more, and even more preferably 0.5 μm or more. On the other hand, by setting the average thickness of each side of the film portion 22 to 1.5 μm or less, the conductivity of the plating layer 12 through the film portion 22 can be ensured. For example, the plating layer 12 can be electrodeposited or spot-welded through the film portion 22. The average thickness of each side of the film portion 22 is more preferably 1.2 μm or less, and even more preferably 1.0 μm or less.

[0156] It should be noted that the average thickness of the coating portion 22 can be measured as follows. First, the portion of the adhesive bonding structure 1 where the coating portion 22 is disposed is cut along the thickness direction of the coating portion 22 to expose the cross-section. This cross-section is then further ground to obtain a cross-sectional sample of the coating portion 22 of the first component 2 in the thickness direction. Next, the coating portion 22 of the cross-sectional sample is observed using a scanning electron microscope to obtain an observation image of the cross-section of the coating portion 22. For the coating portion 22 present in the field of view of this observation image, the thickness is measured at five locations obtained by dividing the field of view into five equal parts along the width direction, and the average value is calculated. The average thickness of the coating portion 22 is set as the average value of the values ​​obtained in the five fields of view. That is, the average thickness of the coating portion 22 is set as the average value of the thickness at a total of 25 locations.

[0157] It should be noted that a known chemically converted film can also be formed on the part of the first component 2 that is not in contact with the adhesive layer 4.

[0158] Figure 2-2 yes Figure 1-1 The enlarged cross-sectional view of the bonding area of ​​the adhesive bonding structure shown is an enlarged cross-sectional view showing the shape of the coating 12, film 22 and adhesive layer 4 of the coated steel 21 (first component 2).

[0159] like Figure 2-2 As shown, the thickness of the film portion 22 is relatively small compared to the surface unevenness of the coating layer 12. The film portion 22 does not completely embed the recesses of the uneven surface; rather, the surface morphology of the film portion 22 reflects the unevenness of the coating layer 12's surface. When an adhesive layer 4 is further laminated on the film portion 22, the adhesive layer 4 penetrates into the recesses of the coating layer 12's surface. This results in a so-called anchoring effect, further increasing the adhesive strength of the adhesive layer 4.

[0160] <Regarding Component 2, Part 3> In this embodiment, the second component 3 may also be the same as the first component 2. That is, it may be a component having the steel 11 described above and the plating 12 disposed on a portion of the surface of the steel 11, or it may be a component further having a film portion 22.

[0161] Furthermore, the second component 3 can also be a component formed of alloyed hot-dip galvanized steel. In this case, the adhesive layer is bonded to the surface of the alloyed hot-dip galvanized layer of the alloyed hot-dip galvanized steel. Additionally, when the second component 3 is formed of alloyed hot-dip galvanized steel, the aforementioned film portion 22 can also be disposed on the surface of the alloyed hot-dip galvanized layer. In this case, the adhesive layer is bonded to the surface of the alloyed hot-dip galvanized layer through the film portion 22. Alloyed hot-dip galvanized steel is steel obtained by galvanizing steel and then alloying it, causing iron to diffuse into the zinc coating. The strength reduction caused by the adhesive over time is further suppressed, making it more suitable as the second component 3.

[0162] If the coating of the alloyed hot-dip galvanized steel contains Fe: 7-15% by mass, Al: 0.05-0.5% by mass, and the remainder contains Zn and impurities, the adhesive strength is less likely to decrease over time, making it more suitable as the second component 3. In this embodiment, the alloyed hot-dip galvanized layer refers to a coating with an Fe-Zn alloy as the main component, formed by the diffusion of Fe from the steel into the Zn coating through an alloying reaction. The Fe content is not particularly limited, but when the Fe content in the alloyed hot-dip galvanized layer is less than 7% by mass, a soft Zn-Fe alloy forms on the coating surface, deteriorating the pressing formability. If the Fe content exceeds 15% by mass, an overdeveloped, brittle alloy layer at the base metal interface deteriorates the coating adhesion. Therefore, the Fe content in the alloyed hot-dip galvanized layer is preferably 7-15% by mass. Furthermore, during continuous hot-dip galvanizing, Al is typically added to the plating bath to control the alloying reaction, resulting in a coating containing 0.05 to 0.5% by mass of Al. Additionally, elements added to the steel simultaneously with Fe during alloying also diffuse, thus these elements are also present in the coating.

[0163] Furthermore, the second component 3 can also be a component formed of fiber-reinforced plastic material. In this case, the second component 3 may not have the aforementioned membrane portion 22. Figure 3 The diagram shows an enlarged view of the cross-section of an adhesive joint structure comprising a second member without a membrane portion 22 and a first member with a membrane portion 22. Figure 3This is a schematic diagram illustrating the positional relationship between the film portion 22A, the adhesive layer 4A, the first component 2A, and the second component 3A, as well as the organic compound phase contained in the film portion 22A.

[0164] Figure 3 The adhesive bonding structure 1A shown has a first component 2A and a second component 3A, which are bonded together by an adhesive layer 4A. The first component 2A has a plated steel 21A and a film portion 22A formed on the surface of the plated layer of the plated steel 21A. Furthermore, the film portion 22A has resin particles 221 and an organic compound phase 223. The second component 3A is bonded to the first component 2A via the adhesive layer 4A. However, unlike the embodiment described above, the second component 3A does not have a film portion 32A.

[0165] The fiber-reinforced plastic material, which is the second component 3A in this case, is formed by compounding a matrix resin with reinforcing fibers. Examples of reinforcing fibers used in fiber-reinforced plastics include glass fibers and carbon fibers.

[0166] Furthermore, the second component 3 can also be made of aluminum alloy. If the second component 3 is made of aluminum alloy, lightweighting of the bonded structure can be achieved, making it suitable. Examples of aluminum alloys include those containing one or more of the following: Si, Fe, Cu, Mn, Mg, Cr, Zn, Ti, V, Zr, Pb, and Bi. For example, commonly known aluminum alloys such as those in the 1000, 2000, 3000, 4000, 5000, 6000, and 7000 series as described in JIS H4000:2006 can be used as the material for the second component 3. The 5000 and 6000 series, which possess strength and formability, are suitable as the second component 3.

[0167] Furthermore, the second component 3 can also be a magnesium alloy. Magnesium alloys containing one or more of the following elements can be used as the material for the second component 3: Al, Zn, Mn, Fe, Si, Cu, Ni, Ca, Zr, Li, Pb, Ag, Cr, Sn, Y, Sb, and other rare earth elements. Commonly known magnesium alloys such as the AM series (containing Al as described in ASTM standards), the AZ series (containing Al and Zn), and the ZK series (containing Zn) can be used.

[0168] In any of the above cases, the adhesive durability of the adhesive joint structure 1A is excellent.

[0169] <Regarding adhesive layer 4> The adhesive layer 4 is disposed in the bonding area 5 between the first component 2 and the second component 3 to bond the first component 2 and the second component 3.

[0170] The adhesive layer 4 is mainly composed of an adhesive. The effect brought about by the aforementioned film portion 22 is not impaired by the type of adhesive constituting the adhesive layer 4. Therefore, there are no particular limitations on the adhesives that can be used in the adhesive layer 4. For example, epoxy resin-based adhesives, polyester resin-based adhesives, urethane resin-based adhesives, adhesives obtained by mixing rubber and elastomers into these adhesives, and adhesives that impart conductivity can be used. From the viewpoint of initial adhesive strength, the adhesive layer 4 preferably contains an epoxy resin-based adhesive or a urethane resin-based adhesive (i.e., a thermosetting adhesive).

[0171] Furthermore, the resin constituting the adhesive layer 4 preferably has a common chemical structure with at least one of the resins in the film portion 22 and the film portion 32. This further enhances the initial adhesion between the adhesive layer 4 and the film portions 22 and 32, thereby further improving the adhesive strength of the bonded structure 1.

[0172] For example, the resin constituting the adhesive layer 4 may also have a common main framework with at least one of the resins in the film portion 22 and the film portion 32. Alternatively, the resin constituting the adhesive layer 4 may also have side chain functional groups common with at least one of the resins in the film portion 22 and the film portion 32.

[0173] The adhesive bonding structure 1 according to this embodiment has been described in detail above. According to this embodiment, since at least the first member 2 is formed of plated steel 21, and the surface of the plating layer 12 of the plated steel 21 is made with an uneven surface, at least a portion of the plurality of blocky binary eutectic structures or the plurality of blocky ternary eutectic structures contained in the plating layer continuously exist from the surface of the plating layer to a position where the average thickness of the plating layer is 1 / 2. Therefore, the adhesion of the adhesive layer 4 to the plating layer 12 is improved, and the adhesion durability is improved. Furthermore, since the plating layer is a Zn-Al-Mg based hot-dip galvanized plating layer, the end-face contactability is particularly excellent. Therefore, the adhesive bonding structure 1 of this embodiment is an adhesive bonding structure with excellent adhesion durability and corrosion resistance.

[0174] Furthermore, the resin particles 221 and organic compound phase 223 in the film portion 22 and film portion 32 can suppress the penetration of water into the interface between the first component 2 and the adhesive layer 4, and the interface between the second component 3 and the adhesive layer 4. As a result, the deterioration of the adhesive layer 4 and the corrosion of the first component 2 and the second component 3 can be suppressed. Therefore, the adhesive bonding structure 1 becomes an adhesive bonding structure that can suppress the reduction of adhesive strength and has better adhesive durability.

[0175] (Regarding variations) The above describes one embodiment of the present disclosure. Hereinafter, several variations of the above embodiment of the present disclosure will be described. It should be noted that each variation described below can be applied individually to the above embodiment of the present disclosure, or can be applied in combination to the above embodiment of the present disclosure. Furthermore, each variation can replace the configuration described in the above embodiment of the present disclosure, or can be additionally applied relative to the configuration described in the above embodiment of the present disclosure. Hereinafter, the description will focus on the differences between the above embodiment and each variation; similar matters may be omitted from the description.

[0176] The second component 3A is not limited to the above-described embodiments and can be made of any material.

[0177] For example, in addition to the materials mentioned above, resin materials, ceramic materials, etc., can also be used as materials that can be used in the second component 3A.

[0178] Furthermore, the second component 3 can also be made of steel materials other than those mentioned above. For steel materials, any surface treatment can be applied. Here, surface treatment includes, for example, various plating treatments such as zinc-based plating, aluminum-based plating, and tin-based plating; chemical conversion treatments such as zinc phosphate treatment, chromate treatment, and chromate-free treatment; and chemical surface roughening treatments such as physical or chemical etching, such as sandblasting, but is not limited to these. In addition, various surface treatments can be applied. As a surface treatment, it is preferable to at least perform a treatment aimed at imparting rust resistance.

[0179] In particular, coated steel, which has undergone plating treatment, is preferred as the metal part 21 due to its excellent corrosion resistance. Examples of coated steel particularly preferred as the metal part 21 include zinc-plated steel, Ni-plated steel, alloyed Ni-plated steel, Al-plated steel, tin-plated steel, and chromium-plated steel.

[0180] Among the various coated steels mentioned above, zinc-coated steel sheets are suitable as metal parts 21 due to their excellent corrosion resistance.

[0181] Furthermore, when component 3 is electro-galvanized steel, it can be steel that is only coated with zinc (generally referred to as EG), or it can be zinc-nickel electroplated steel. In addition, hot-dip galvanized steel can be steel that contains 0.2% Al in the zinc coating, generally referred to as GI, or it can be steel that contains 1 to 10% Al in the zinc coating, generally referred to as Zn-Al alloy coated steel sheet.

[0182] Furthermore, the shape of the adhesive bonding structure according to this embodiment is not limited to the shape of the embodiment described above. The shapes of the first member and the second member constituting the adhesive bonding structure according to this embodiment can be set to any shape, and the bonding portion of the first member and the second member can also be selected from any location. Furthermore, the adhesive bonding structure according to this embodiment may also have other members besides the first member and the second member. Figure 4 , Figure 5 This is a schematic perspective view of an adhesive bonding structure involved in other variations of this embodiment. Figure 6 This is a schematic diagram illustrating the bonding state of the adhesive joint structure involved in other variations of this embodiment.

[0183] Figure 4 The adhesive bonding structure 1B shown has a cap-shaped first member 2B and a flat plate-shaped second member 3B. In the adhesive region 5B located on the flange of the first member 2B, the second member 3B is bonded to the first member 2B through an adhesive layer 4. Figure 5 The adhesive bonding structure 1C shown has a cap-shaped first member 2C and a cap-shaped second member 3C, which are arranged such that their respective flanges face each other. Furthermore, the opposing flanges of the first member 2C and the second member 3C are bonded together by an adhesive layer 4C, forming an adhesive region 5C. Furthermore, Figure 6 The adhesive bonding structure 1D shown is formed by covering the end of the plate-like portion of the first member 2D with a folded edge by the second member 3D. Moreover, in the folded edge, the first member 2D and the second member 3D are bonded together by an adhesive layer 4D.

[0184] exist Figures 4-6 In any of the variations shown, since at least the first member 2 is formed of coated steel 21, the surface of the coating 12 of the coated steel 21 is made into an uneven surface, and at least a portion of the multiple blocky binary eutectic structures or multiple blocky ternary eutectic structures in the coating are continuously present from the surface of the coating up to a position where the average thickness of the coating is 1 / 2, the adhesive durability and corrosion resistance of the adhesive joint structures 1B to 1D are also excellent.

[0185] Furthermore, in the above embodiments, the case in which the first member 2 and the second member 3 are bonded only by the adhesive layer 4 has been described, but this disclosure is not limited to this, and the bonding using the adhesive layer can be combined with other bonding methods (second bonding).

[0186] As a second joint that can be combined with adhesive bonding, there are no particular limitations, and any joining method can be used. Specifically, examples of such joining methods include fusion bonding, non-fusion bonding, and mechanical bonding.

[0187] As a fusion bonding method, spot welding, arc welding, laser welding, etc., can be used. Fusion bonding can be applied when both the first component and the second component have metallic parts. It should be noted that fusion bonding can also be performed after removing the adhesive layer, but if the adhesive layer is conductive, it can be performed without removing the adhesive layer.

[0188] Examples of non-fusion joints include friction stir joints, diffusion joints, and press joints. Examples of mechanical joints include riveting joints and joints using screws.

[0189] (Regarding the purpose) Next, the applications of the adhesive bonding structure disclosed herein will be described. The applications of the adhesive bonding structure disclosed herein are not particularly limited, and it can be used as a component in any machinery, building, structure, etc. In particular, the adhesive bonding structure disclosed herein exhibits excellent water resistance and adhesion, and is relatively lightweight due to the use of an adhesive. Therefore, the adhesive bonding structure disclosed herein is suitable for components of conveying equipment that are easily placed in environments exposed to water and where lightweight is always required, particularly automotive components. Therefore, in one aspect, this disclosure also relates to automotive components incorporating the adhesive bonding structure disclosed herein.

[0190] As for automotive components using the adhesive bonding structure disclosed herein, there are no particular limitations, but examples include closed-section components bonded by flanges (e.g., A-pillars, B-pillars, side beams, etc.), components partially laminated with materials for the purpose of strengthening / reinforcing (e.g., B-pillar reinforcements, outer panels), and panel components (doors, covers, etc.) with folded edges.

[0191] (Regarding the manufacturing method of adhesive joint structures) Next, the manufacturing method of the adhesive bonding structure 1 according to this embodiment will be described.

[0192] like Figure 7As shown in the flowchart, the manufacturing method of the adhesive bonding structure 1 according to this embodiment includes: a component forming process for forming a first component 2 and a second component 3 constituting the adhesive bonding structure 1, and an adhesive bonding process for bonding the formed first component 2 and second component 3 together using a specified adhesive.

[0193] <Component Formation Process> like Figure 7 As shown in the flowchart, the component forming process includes: a base material manufacturing process for manufacturing base materials of the first component 2 and the second component 3 using raw materials; a film forming process for forming the film portion 22 by applying a film coating liquid for forming the film portion 22 to at least a portion of the base material of the first component 2 and then drying or baking it; and a forming process for shaping the base material of the first component 2 and the base material of the second component 3 to which the film portion 22 is formed into a desired shape as needed.

[0194] Base Material Manufacturing Process In the base material manufacturing process, the base materials of the first component 2 and the second component 3 are manufactured using the raw materials of the first component 2 and the second component 3. There are no particular limitations on the manufacturing method of the base material; it is acceptable to use any known manufacturing method for forming the desired base material and manufacture the base material according to conventional methods.

[0195] For example, when using zinc-coated steel sheets as the first component 2 and the second component 3, hot-rolled or cold-rolled steel sheets are manufactured using conventional methods, and a zinc coating is formed on the resulting hot-rolled or cold-rolled steel sheets using conventional methods. Furthermore, even when using other metal materials, resin materials, FRP materials, ceramic materials, etc., as the base material, these materials can be manufactured using various known manufacturing methods according to conventional methods. The manufacturing method of the coated steel will be described below when coated steel is used as the first component 2.

[0196] The method for manufacturing coated steel according to this embodiment involves annealing a steel sheet in a reducing atmosphere, immersing the freshly annealed steel sheet in a hot-dip galvanizing bath, and then removing it to form a coating on the surface of the steel sheet. Next, cooling is performed by blowing cooling gas while the temperature of the coating rises from the bath temperature to 260°C. During this process, the oxygen concentration in the atmosphere above the galvanizing bath surface and the oxygen concentration in the atmosphere from when the steel sheet is removed from the galvanizing bath until cooling is complete are controlled to be within the range of 100 to 5000 ppm. Furthermore, the average cooling rate during the period from the bath temperature to 260°C is set to 15°C / second or higher. Cooling is further performed by spraying cooling gas, but the dew point of this cooling gas is set to 0°C or higher.

[0197] That is, the manufacturing method of the plated steel in this embodiment is as follows: Figure 7 As shown in the flowchart, it has the following steps: (S1) The process of annealing the steel plate in a reducing atmosphere; (S2) The process of immersing the steel sheet in a hot-dip galvanizing bath; (S3) The process of removing the steel sheet from the hot-dip galvanizing bath; and (S4) The process of blowing cooling gas onto steel sheets coated with hot-dip galvanizing bath. (A) In immersion S2 and retrieval S3, the oxygen concentration in the atmosphere on the surface of the hot-dip plating bath is set to a range of 100 to 5000 ppm. (B) In the blowing process S4, the dew point of the cooling gas is set to above 0°C. (C) In the blow coating S4 process, the average cooling rate of the coating temperature from the hot-dip plating bath temperature to 260°C is set to 15°C / second or higher. (D) In ​​the blowing process S4, the oxygen concentration in the atmosphere during the period from when the steel sheet is removed from the plating bath until the cooling is complete is set to a range of 100 to 5000 ppm. By combining all conditions A, B, C, and D, the plated steel of this embodiment can be obtained. Hereinafter, the details of the manufacturing method of the plated steel will be described in sequence.

[0198] (S1 annealing) Annealing of the steel sheet used as the base for plating is carried out in a reducing atmosphere. There are no particular limitations on the reducing atmosphere or annealing conditions. This annealing process removes as much of the oxide present on the surface of the steel sheet as possible.

[0199] (S2 impregnation) Next, the freshly annealed steel sheet is immersed in a hot-dip galvanizing bath. The chemical composition of the galvanizing bath can be appropriately adjusted to obtain the chemical composition of the coating described above. Furthermore, there are no particular limitations on the temperature of the galvanizing bath; a suitable temperature for hot-dip galvanizing can be selected. For example, the galvanizing bath temperature can be set to a value approximately 20°C or higher than the melting point of the galvanizing bath.

[0200] (S3 fished up) Next, the steel sheet is removed from the plating bath. The amount of coating adhesion can be controlled by adjusting the removal speed of the steel sheet. If necessary, the coated steel sheet can also be wiped to control the amount of coating adhesion. There are no particular limitations on the amount of coating adhesion; for example, it can be set within the range described above.

[0201] (S4 blow attachment) Next, the coating is cooled. Cooling is achieved by blowing cooling gas onto the steel sheet immediately after it has been removed from the hot-dip galvanizing bath. Cooling by blowing cooling gas is carried out continuously while the temperature of the steel sheet rises from the bath temperature to 260°C. Cooling conditions below 260°C are not particularly limited; cooling by blowing cooling gas or natural cooling can then be performed.

[0202] The oxygen concentration in the atmosphere above the plating bath surface and the oxygen concentration in the atmosphere from when the steel plate is removed from the plating bath until cooling is complete are controlled to be in the range of 100 to 5000 ppm. Preferably, these oxygen concentrations are in the range of 100 to 1000 ppm. When the molten metal of the plating bath adhering to the steel plate solidifies, an oxide film forms on the outermost surface of the molten metal in the early stage of solidification, but the thickness of the oxide film is affected by the oxygen concentration in the atmosphere. If the oxide film becomes of a suitable thickness, it will follow the shape change of the coating surface during subsequent solidification, forming an uneven surface that satisfies the above formula (1).

[0203] When the oxygen concentration in the atmosphere above the plating bath and during the period from when the steel plate is removed from the plating bath until cooling is complete is below 100 ppm, an oxide film of sufficient thickness is not formed, making it difficult to create an uneven surface for the coating. Furthermore, if the oxygen concentration in the atmosphere exceeds 5000 ppm, a relatively thick oxide film with a flat surface is formed in the early stages of solidification. This oxide film does not follow the shape changes of the coating surface during solidification, resulting in a flat surface after solidification, which fails to satisfy the above formula (1). Moreover, if the oxygen concentration in the atmosphere exceeds 5000 ppm, the oxide film may become prone to cracking, making it difficult to maintain the shape of the coating during solidification.

[0204] There are no particular limitations on the means by which the oxygen concentration in the atmosphere above the plating bath surface is set to be in the range of 100 to 5000 ppm. For example, a cover can be provided to cover the surface of the plating bath, and a gas with an oxygen concentration of 100 to 5000 ppm can be supplied to the inside of the cover. There are no particular limitations on the type of gas supplied to the surface of the plating bath, as long as the oxygen concentration is in the range of 100 to 5000 ppm. It can be a non-oxidizing gas such as nitrogen, an inert gas such as argon, or a mixture of them.

[0205] To ensure the oxygen concentration in the atmosphere during the period from when the steel sheet is removed from the plating bath until cooling is complete, it is sufficient to set the oxygen concentration of the cooling gas blown onto the steel sheet to be within the range of 100 to 5000 ppm. If atmospheric air is used as the cooling gas, the oxygen concentration becomes excessive, resulting in an unsuitable coating.

[0206] Furthermore, by setting the dew point of the cooling gas to above 0°C, the shape of the oxide film can be maintained. If the dew point of the cooling gas becomes below 0°C, a coating with a surface shape satisfying the above formula (1) cannot be obtained. There are no particular restrictions on the type of cooling gas as long as the oxygen concentration is in the range of 100 to 5000 ppm. It can be a non-oxidizing gas such as nitrogen, an inert gas such as argon, or a mixture thereof.

[0207] Furthermore, the average cooling rate during the period from the bath temperature to reaching 260°C is set to 15°C / second or higher. There is no particular upper limit to the average cooling rate, but it can be, for example, 200°C / second or lower. By setting the average cooling rate to 15°C / second or higher, sufficient Al primary crystals (Al phase) and Al-Zn are formed in the initial stage of the solidification process. It should be noted that the average cooling rate during the period from the bath temperature to reaching 260°C is calculated using the following formula. Cooling time refers to the time from when the steel sheet is removed from the plating bath until the temperature of the plating layer decreases to 260°C.

[0208] Average cooling rate = (bath temperature - 260) ÷ cooling time In the initial stage of solidification, as the primary Al crystals (Al phase) and Al-Zn phase fully crystallize, the amount of molten metal on the steel plate surface decreases. Furthermore, if the crystallization of binary and ternary eutectic structures begins as the temperature of the molten metal decreases, these eutectic structures form by burying the already crystallized Al and Al-Zn phases. Since the crystallization of eutectic structures begins at the stage when the residual amount of molten metal decreases, the binary and ternary eutectic structures become the structures forming the recessed areas of the coating. Moreover, the crystallization of the eutectic structure mainly begins in the region of the coating close to the steel plate, more specifically, starting with the nucleation of the Fe-Al interfacial alloy layer on its surface, and crystallizing towards the surface of the coating. Thus, the binary and ternary eutectic structures continuously exist from the steel plate side of the coating towards the surface side.

[0209] Furthermore, in this embodiment, after the steel is manufactured, a process can be performed to induce cracks in the coating. Specifically, a bending recovery process using a tension leveling machine and a surface rolling process can also be performed. As conditions for these processes, it is preferable to set a strain of 0.2 to 2.0% total elongation to the steel, thereby inducing cracks in the coating and further improving the adhesion to the adhesive layer 4.

[0210] Skin Membrane Formation Process In this embodiment, the film-forming process may or may not be performed. When the film portion 22 is formed on the first component 2 or the second component 3, the film-forming process is performed. In the film-forming process, for example, when the film portion 22 is formed on the plated steel 21 which is the first component 2, a film coating liquid for forming the film portion 22 is applied to at least a portion of the plating 12, followed by drying or baking, thereby forming the film portion 22.

[0211] Here, there is no particular limitation on the manufacturing method of the coating solution. For example, a solvent such as water corresponding to the organic resin used can be used. In the solvent, an organic resin containing one or more of urethane groups, epoxy groups, and ester groups and an organosilicon compound containing at least one of Si-C bonds, Si-O bonds, or Si-OH bonds can be mixed and stirred by various known methods.

[0212] There are no particular limitations on the method for applying the coating liquid used to form the film portion 22, and various known methods can be appropriately used. For example, when the coating liquid is a viscous liquid, known methods such as spraying from a slit nozzle or a round nozzle, brush coating, doctor blade coating, and shovel coating can be used to apply the coating liquid. Furthermore, when using a coating liquid obtained by dissolving the above-mentioned components in a specified solvent, various known coating methods such as brush coating, spray coating, bar coating, spray coating from nozzles of various shapes, die coating, curtain coating, roller coating, and inkjet coating can be used. In addition, various known methods such as bar coating, roller coating, screen printing, and powder coating can be employed.

[0213] In the case of forming a film on the plated steel according to this embodiment, it is preferable to apply the film coating solution within 60 minutes after the formation of the coating. If the time until the film coating solution is applied is less than 60 minutes, chemical bonds are easily formed between the organosilicon compound and the coating, and therefore, when analyzed by TOF-SIMS, the count of peaks corresponding to Si-O-Me bonds (Me: metal element) is 15 or more. Furthermore, if the time until the film coating solution is applied is less than 60 minutes, the value obtained by dividing the peak count representing Si-O-Me bonds by the sum of all two ion counts detected within the mass scan range m / z = 0 to 300 (Total Ion correction value) is 1.0 × 10⁻⁶. -3 above.

[0214] Furthermore, drying and baking can be performed, for example, by heat treatment. There are no particular limitations on the heating conditions; for example, a drying / baking time of 5 seconds to 30 minutes can be set at a temperature of 80°C or higher and 250°C or lower.

[0215] Forming and processing procedures In the forming process, the first component 2 and the second component 3, on which the film portion 22 is formed, are formed into a desired shape as needed. Here, there is no particular limitation on the forming method, as long as a processing means for obtaining the shape of the target molded article is selected from known metal processing methods. In addition, if necessary, a part of the forming process and the bonding process described later may be performed simultaneously.

[0216] <Adhesive bonding process> The bonding process involves joining the formed first component 2 and second component 3 using a prescribed adhesive. In this process, firstly, a desired adhesive is applied to the bonding portions (e.g., flanges) of the obtained first component 2 and second component 3 to form a bonding region 5. Then, the first component 2 and second component 3 are laminated through the bonding region 5 and subjected to heat treatment to cure the adhesive. Here, the method for applying the desired adhesive is not particularly limited; any application of the desired adhesive or preparation of a desired adhesive resin sheet is acceptable. Thus, the bonding structure 1 according to this embodiment, formed by bonding the first component 2 and second component 3 together through an adhesive layer 4, can be obtained.

[0217] It should be noted that various coating treatments and other joining treatments can also be performed in the above-mentioned bonding and joining process as needed. For example, as a joining treatment, mechanical joining using bolts or rivets, welding treatments such as spot welding, etc., can also be performed.

[0218] More specifically, for example, in manufacturing Figure 6 In the case of the adhesive bonding structure 1D shown, adhesive is applied to one or both sides of the flange portion that joins the first member 2 and the second member 3, the joint portion of the first member 2 and the second member 3 is layered with adhesive, and the adhesive is cured by holding at room temperature or by heat treatment, thereby obtaining the desired structure.

[0219] Furthermore, for example, in the case where the first component 2, which is a metal component, is reinforced by the second component 3, which is a fiber-reinforced plastic, as shown in FIG1, the adhesive joint structure 1 can be obtained by thermoforming in a state in which the first component 2 and the second component 3 are laminated through an adhesive.

[0220] The manufacturing method of the adhesive bonding structure 1 according to this embodiment has been briefly described above. It should be noted that the adhesive bonding structure according to this disclosure is not limited to being manufactured by the above-described manufacturing method, and can be manufactured by any manufacturing method.

[0221] Example The present disclosure will now be described in more detail through embodiments. It should be noted that the embodiments described below are merely examples of the present disclosure and do not limit the scope of the disclosure.

[0222] Manufacturing of coated steel First, the following steps are used to manufacture coated steel.

[0223] For the base plate, cold-rolled steel sheet (0.05C-0.1Si-0.2Mn) with a thickness of 1.6 mm was used. First, the steel sheet was annealed. A coating was then applied to the surface of the annealed steel sheet by immersing it in various hot-dip galvanizing baths and then removing it. Next, various coated steel sheets were manufactured by cooling them with cooling gas from the moment they were removed from the galvanizing bath until the coating reached 260°C. The cooling gas was set to consist primarily of nitrogen. The oxygen concentration and dew point of the cooling gas were set as shown in Tables 2A and 2B.

[0224] For the annealing conditions of the steel sheet in a reducing atmosphere, the soaking temperature was set to 800℃ and the soaking time to 10 seconds. The annealing atmosphere was set to a reducing atmosphere containing a mixture of 5% hydrogen and the remainder nitrogen. The oxygen concentration in the annealing atmosphere was set to below 20 ppm. Then, the annealed steel sheet was air-cooled with nitrogen until the plate temperature reached the bath temperature +20℃, and then immersed in the hot-dip galvanizing bath for about 3 seconds before being removed. The removal speed was set to 20–200 mm / s. During removal, the coating adhesion was controlled by wiping with N2 gas.

[0225] The chemical composition of the coating is as shown in Tables 1A and 1B. The manufacturing conditions are set as shown in Tables 2A and 2B. Furthermore, the morphology of the binary or ternary eutectic structure in the coating was evaluated, and the results are shown in Tables 3A and 3B. Next, the coating adhesion and end-face corrosion resistance of the coated steel sheet were evaluated, and the results are shown in Tables 4A and 4B.

[0226] The chemical composition, metallic structure, and surface roughness of the coating were evaluated using the methods described above. It should be noted that the evaluation of the surface roughness was performed by setting the length Lo of the coating along its length to a field of view of 500 μm. Furthermore, the presence or absence of the Mg₂Sn phase was determined by X-ray diffraction analysis of the coating surface, and the presence or absence of Mg₂Sn diffraction peaks was confirmed.

[0227] <Formation of the dermis> Next, for a portion of the plated steel, a coating is formed through the following steps.

[0228] First, for the formation of the skin layer, prepare the following 5 chemical conversion treatment agents.

[0229] (A1) A chemical conversion treatment agent A1 is prepared by mixing water-dispersible emulsion type polyurethane resin SF-150 manufactured by Daiichi Kogyo Co., Ltd. and 3-epoxypropoxypropyltriethoxysilane in a ratio of 3:2 based on the volume ratio of solid components.

[0230] (A2) A chemical conversion treatment agent A2 is prepared by mixing water-dispersible emulsion type polyurethane resin SF-150 manufactured by Daiichi Kogyo Co., Ltd. and 3-epoxypropoxypropyltriethoxysilane in a ratio of 5:1 based on the solid component volume ratio.

[0231] (A3) A chemical conversion treatment agent A3 is prepared by mixing SF-150, a water-dispersible emulsion type polyurethane resin manufactured by Daiichi Kogyo Co., Ltd., and 3-epoxypropoxypropyltriethoxysilane in a ratio of 1:5 based on the volume ratio of solid components.

[0232] (B) Dissolve the polyester resin VYLON GK140 manufactured by Toyobo Co., Ltd. in the solvent cyclohexanone, and mix the imino-type melamine CYMEL325 manufactured by Cytec Industries Co., Ltd. of Japan with the resin in a solid volume ratio of 5:1. Add a curing catalyst (Catalyst 296-9: Cytec Industries Co., Ltd. of Japan) in an amount of 0.1% by volume relative to the solid content of the resin to adjust the resin solution and prepare chemical conversion treatment agent B.

[0233] (C) Chemical conversion agent C for preparing an aqueous solution of only 3-epoxypropoxypropyltriethoxysilane.

[0234] By applying the above-mentioned chemical conversion treatment agent to the coating of the plated steel in such a way as shown in Tables 3A and 3B below, and drying and baking it in an induction heating furnace at a maximum plate temperature (PMT) of 150°C, a film is formed.

[0235] <Preparation of Component 1 and Component 2> As shown in Tables 1A to 3B, Examples 1 to 29 and Comparative Examples 30 to 35 used the plated steel manufactured through the above steps as the first component.

[0236] Furthermore, regarding the second component, in Examples 1-10, 12-15, 18-29 and Comparative Examples 30-35, the same raw material as the first component was used as the second component. In Tables 4A and 4B, for the level of using the same raw material as the first component as the raw material of the second component, the column for "second component" is recorded as "same as above".

[0237] Furthermore, for the second component, in Example 11, an alloyed hot-dip galvanized steel sheet (GA) with a thickness of 1.0 mm and a tensile strength of 980 MPa is used as the second component.

[0238] Furthermore, in Example 16, a standard A5000 series aluminum plate with a thickness of 1.0 mm and a tensile strength of 290 MPa was used as the second component.

[0239] Furthermore, in Example 17, a commercially available CFRP sheet with a thickness of 1.0 mm was used as the second component.

[0240] <Adhesive bonding treatment> By molding the prepared first and second components, a flanged metallic cap-shaped component is produced. As an adhesive for bonding the first and second components, an adhesive containing 5% by mass of 200μm glass beads is prepared relative to Penguin Cement#1066, an epoxy resin-based adhesive manufactured by Sunstar Corporation.

[0241] For each combination of the first and second components shown in Tables 1A to 3B below, the adhesive described above is applied to the surface of the first component, and the second component is further attached thereon. The adhesive is cured by placing it on the surface in an atmosphere at 170°C for 30 minutes to create a closed-section structure.

[0242] It should be noted that in Examples 10, 13, 16, and 20, structures were fabricated using spot welding on the parts coated with adhesive. Specifically, CF-type Cr-Cu electrodes with a front diameter of 5 mm and an R40 diameter were used, and spot welding was performed with a weld nugget diameter of 3 × t0.5 (t being the plate thickness [mm]) and a spot interval of 30 mm. It should be noted that no adhesive was applied to the predetermined spot welding sections.

[0243] <Electrodeposition Coating of Cap Components> To observe the bonding condition under corrosive conditions, for cap-shaped components that have undergone the bonding treatment described above, Zn phosphate treatment was performed (SD5350 system: according to Nippon paint Industrial Coatings standard), followed by electrodeposition coating at 20 μm (PN110 Powernics Gray: Nippon paint Industrial Coatings standard), and baking at 150°C for 20 minutes.

[0244] <Evaluation of Adhesive Joint Structures> Prepare multiple samples from which a portion of the obtained adhesive joint structure is cut out. For the vertical cross-section near the interface between the first component and the adhesive layer, perform micro-infrared spectroscopy and TOF-SIMS analysis according to the methods described above.

[0245] It should be noted that in the micro-infrared spectroscopy and TOF-SIMS analysis, the film portion of the vertical cross-section near the interface between the first component and the adhesive layer in the obtained bonded structure was magnified by cutting at a 5-degree angle using a tilting cutting device (SAICAS, DAIPLA WINTES DN-20S type). The micro-infrared spectroscopy instrument used was an IRT-5200 manufactured by Nippon Spectroscopy Co., Ltd., and the TOF-SIMS used was a TOF-SIMS TRIFT-V manufactured by ULVAC-PHI Co., Ltd.

[0246] Here, in the micro-infrared spectroscopy analysis, the aforementioned micro-infrared spectroscopy analysis apparatus is used for mapping measurement. The attribution of the observed peaks representing the resin component in the infrared absorption spectrum of the obtained film portion determines whether it contains one or more of the following: aqueous polyurethane resin, epoxy resin, and polyester resin. Specifically, in the obtained infrared absorption spectrum, at 910 cm⁻¹... -1 If a peak is observed nearby, it is determined to contain epoxy groups, at 1550 cm⁻¹. -1 Nearby and 1740cm -1 If a peak is observed nearby, it is determined to contain carbamate groups, and the peak is located at 1720–1740 cm⁻¹. -1 If a peak is observed nearby, it is determined to contain an ester group. It should be noted that, in the following, cases where it is determined to contain at least one of an epoxy group, a carbamate group, or an ester group will be described as "present," and cases where it is determined not to contain these functional groups will be described as "absent."

[0247] Furthermore, in TOF-SIMS analysis, using the aforementioned apparatus, an arbitrary point on the portion where the adhesive layer thickness is reduced to approximately 1 μm is analyzed while simultaneously sputtering argon from one side of the adhesive layer toward the side of the metal component. After sputtering Ar ions to a certain depth from the surface, TOF-SIMS measurements are performed. This process is repeated to obtain the depth-direction distribution for various elements and bonds. The primary ion species is Au. 3 + The accelerating voltage was 30 kV, the sputtering velocity was approximately 80 nm / min (SiO2 conversion), and the measurement area was 50 μm × 50 μm. For the interface between the chemically converted coating layer (or the adhesive layer if no chemically converted coating layer is present) and the metal component, the presence or absence of peaks indicating Si-O-Me bonds and whether the Total Ion correction value exceeded 1.0 × 10⁻⁶ were considered. -3 The following evaluation will be conducted. It should be noted that, in the following, the data will include those with Si-O-Me bonds and a Total Ion correction value of 1.0 × 10⁻⁶. -3 The above situations are recorded as A, which includes those without Si-O-Me bonds or with a Total Ion correction value lower than 1.0 × 10⁻⁶. -3 The situation is recorded as B.

[0248] In addition, a sample cut from a portion of the obtained adhesive joint structure was prepared, and the vertical section near the interface between the first component and the adhesive layer was observed using a SEM (Hitachi SU3800) according to the previously described method, and (Lr-Lo) / Lo (%) was calculated.

[0249] <Adhesion Durability Evaluation> For the adhesive joint structures involved in each of the obtained examples, the durability of the joint was evaluated.

[0250] First, for each example of the bonded structure, the torsional stiffness was determined and calculated using a torsion testing machine. Specifically, both ends of each example of the bonded structure were fixed with clamps, and only one end was rotated about the central axis of the bonded structure, thus applying torsional deformation to the bonded structure. The torsion angle and torsional moment were measured at this time, and the torsional stiffness of each bonded structure was calculated from the relationship between the torsion angle and torsional moment within the elastic deformation range. Specifically, the relationship between the torsion angle and torsional moment within the elastic deformation range was expressed using the initial slope of the torsion angle-torsional moment graph.

[0251] Next, a composite cyclic corrosion test according to JASO (M609-91) was conducted, in which the bonded structures involved in each case were left to stand for 4800 hours to promote the degradation of the adhesive layer and the interface between the adhesive layer and the chemical conversion treatment film layer. For the bonded structures involved in each case after standing in the composite cyclic corrosion tester, the torsional stiffness was measured and calculated using a torsion tester. Then, the torsional stiffness was compared with that of the bonded structures involved in each case that did not undergo the degradation test, and the reduction rate of torsional stiffness caused by degradation was calculated. The obtained reduction rate was used as an evaluation index for the bond durability.

[0252] Calculate the rate of decrease in flexural strength after the combined cyclic corrosion test relative to the flexural strength before the test, and evaluate it according to the following evaluation criteria. A score of C or above is set as acceptable.

[0253] (evaluate) AAA: Reduction rate less than 10% AA: The reduction rate is above 10% but below 20%. A: The reduction rate is above 20% but below 30%. B: The reduction rate is above 30% but below 40%. C: The reduction rate is above 40% but below 50%. D: The reduction rate is over 50%. <Simulated end-face corrosion resistance> Regarding end-face corrosion resistance, multiple samples were prepared by cutting out a portion of the bonded structure, exposing a vertical section near the interface between the first component and the adhesive layer. The vertical section was subjected to a neutral salt spray test as specified in JIS Z 2371, and the evaluation was based on the formation of red rust on the cut end face. The evaluation criteria for red rust area percentage are shown below. "AAA", "AA", and "A" are set as acceptable.

[0254] (evaluate) AAA: The red rust area rate is less than 10% after 2500h. AA: The red rust area rate is less than 10% after 2000 hours. A: The red rust area rate is below 20% after 1500 hours. B: The red rust area exceeds 20% after 1500 hours. The results are shown in Tables 1A to 4B.

[0255] The surface of the coating of the adhesive bonding structure No. 1 to 29 is uneven, and there are multiple blocky binary eutectic structures or ternary eutectic structures in the coating. A portion of the eutectic structure that exists continuously from the surface of the coating up to 1 / 2 of the thickness of the coating or the depth of the Fe-Al interface alloy layer is located in the concave part of the uneven surface. The chemical composition of the coating and the morphology of the eutectic structure are within the scope of this disclosure, and both the adhesion durability and the end face corrosion resistance are excellent.

[0256] The Al content of the coating in No. 30 is insufficient. Therefore, the (Lr-Lo) / Lo×100 of No. 30 becomes smaller, resulting in insufficient adhesion durability.

[0257] The Al content in the coating of No. 31 is excessive. Therefore, the (Lr-Lo) / Lo×100 of No. 31 becomes smaller, resulting in insufficient adhesion durability.

[0258] The Mg content in the coating of No. 32 is insufficient. Therefore, for No. 32, (Lr-Lo) / Lo×100 becomes smaller, resulting in insufficient adhesion durability.

[0259] The Mg content in the coating of No. 33 is excessive. Therefore, for No. 33, (Lr-Lo) / Lo×100 becomes smaller, resulting in insufficient adhesion durability.

[0260] For No. 34, the oxygen concentration in the atmosphere from the plating bath to the end of the cooling process exceeds 5000 ppm. Therefore, for No. 34, (Lr-Lo) / Lo×100 becomes smaller, resulting in insufficient adhesion durability.

[0261] For No. 35, the average cooling rate decreases from the bath temperature to 260°C. Therefore, for No. 35, the primary Al crystals (Al phase or Al-Zn phase) do not crystallize sufficiently, (Lr-Lo) / Lo×100 becomes smaller, resulting in insufficient adhesion durability.

[0262] The suitable embodiments of this disclosure have been described in detail above with reference to the accompanying drawings, but this disclosure is not limited to the examples described. Various modifications or alterations will be readily apparent to anyone skilled in the art to which this disclosure pertains, within the scope of the technical concept set forth in the claims, and such knowledge is also within the technical scope of this disclosure.

[0263] Explanation of reference numerals in the attached figures 1, 1A, 1B, 1C, 1D Adhesive-bonded joint structures 11. Steel 12, 112 coating 13, 113 interface alloy layer 14, 114 Binary eutectic structure or ternary eutectic structure 2, 2A, 2B, 2C, 2D Component 1 21, 21A Metal Parts 22, 22A membrane part 221 Resin Particles 223 Organic compound phase 3, 3A, 3B, 3C, 3D - Component 2 31. Coated steel 32 membrane part 321 Resin Particles 323 Organic compound phase 4, 4A, 4B, 4C, 4D Adhesive layers 5, 5B, 5C bonding areas

Claims

1. An adhesive bonding structure comprising: Component 1 The second component, and An adhesive layer that joins the first component and the second component. in, Either or both of the first component or the second component are plated steel, the plated steel having steel material and a coating disposed on at least a portion of the surface of the steel material. The average chemical composition of the coating, expressed as a percentage by mass, comprises: Al：10.00～30.00%、 Mg: 1.00~15.00%, Sn: 0.00~1.00% Si: 0.00~2.00% Ca: 0.00~2.00% Ni: 0.00~1.00% Fe: 0.01~15.00%, Sb: 0.00~0.50% Pb: 0.00~0.50%, Cu: 0.00~1.00%, Ti: 0.00~1.00%, Cr：0.00～1.00%、 Nb: 0.00~1.00% Zr：0.00～1.00%、 Mn: 0.00~1.00%, Mo: 0.00~1.00% Ag: 0.00~1.00%, Li: 0.00~1.00% Bi: 0.00~1.00% V：0.00～1.00%、 Co: 0.00~1.00%, In: 0.00~1.00% W：0.00～1.00%、 P：0.00～1.00%、 La: 0.00~0.50% Ce: 0.00~0.50% B：0.00～0.50%、 Y：0.00～0.50%、 Sr：0.00～0.50%、 Total of Sb, Pb, Cu, Ti, Cr, Nb, Zr, Mn, Mo, Ag, Li, Bi, V, Co, In, W, P, La, Ce, B, Y, Sr: 0.00~5.00%, Remaining components: Zn and impurities. The surface of the coating is made into an uneven surface. In the cross section of the coating, the relationship between the length Lo of the coating in the longitudinal direction within the observation area of ​​the cross section and the total length Lr of the contour line of the surface of the coating within the observation area satisfies the following equation (1). The coating contains one or both of the following: multiple blocky binary eutectic structures or multiple blocky ternary eutectic structures. At least a portion of the multiple blocky binary eutectic structures or the multiple blocky ternary eutectic structures are continuously present from the surface of the coating up to a position where the average thickness of the coating is 1 / 2. (Lr-Lo) / Lo×100≥2.0 (%) (1).

2. The adhesive bonding structure according to claim 1, wherein, The first component is the plated steel having the steel and the coating. The second component is any one of alloyed hot-dip galvanized steel, fiber-reinforced plastic, aluminum alloy, or magnesium alloy.

3. The adhesive bonding structure according to claim 1, wherein, The plated steel material includes the steel material, the coating, and at least a film portion disposed on the uneven surface of the coating. The adhesive layer connects the first component and the second component through the film portion.

4. The adhesive joint structure according to claim 2, wherein, The plated steel material includes the steel material, the coating, and at least a film portion disposed on the uneven surface of the coating. The adhesive layer connects the first component and the second component through the film portion.

5. The adhesive bonding structure according to claim 3 or claim 4, wherein, The coating portion comprises: an organic resin phase containing one or more of urethane groups, epoxy groups, and ester groups, and an organic compound phase formed from an organosilicon compound containing at least one of Si-O bonds or Si-OH bonds and Si-C bonds. When Ar sputtering is performed on the film portion from the adhesive layer side toward the coating layer side at any location including the interface between the coating and the film portion, and the analysis is performed using time-of-flight secondary ion mass spectrometry, the following scenario is also described. Peaks corresponding to Si-O-Me bonds were observed, and the value obtained by dividing the count of the peaks representing the Si-O-Me bonds by the sum of all two ion counts detected within the mass scan range m / z = 0 to 300 was 1.0 × 10⁻⁶. -3 above, Wherein, Me is one or more of the elements Zn, Al, Mg or Fe that constitute the coating.

6. The adhesive joint structure according to claim 1, wherein, The coating includes an Fe-Al interface alloy layer in contact with the steel. At least a portion of the multiple blocky binary eutectic structures or the multiple blocky ternary eutectic structures are continuously present from the surface of the coating to the Fe-Al interface alloy layer.

7. The adhesive joint structure according to claim 1, wherein, Instead of equation (1), the following equation (2) is satisfied. The number of portions in which at least a portion of the multiple blocky binary eutectic structures or the multiple blocky ternary eutectic structures continuously exist from the surface of the coating up to a position where the average thickness of the coating is 1 / 2 is 3 to 15 portions within a rectangular region of 500 μm long side and 150 μm short side on the surface of the coating. (Lr-Lo) / Lo×100≥6.0 (%) (2).

8. The adhesive joint structure according to claim 1, wherein, Instead of equation (1), the following equation (3) is satisfied. The number of portions in which at least a portion of the multiple blocky binary eutectic structures or the multiple blocky ternary eutectic structures are continuously present from the surface of the coating up to a position where the average thickness of the coating is 1 / 2 is 5 to 15 portions within a rectangular region of 500 μm long side and 150 μm short side on the surface of the coating. (Lr-Lo) / Lo×100≥8.0 (%) (3).

9. The adhesive joint structure according to claim 1, wherein, At least a portion of the multiple blocky binary eutectic structures or the multiple blocky ternary eutectic structures are continuously present from the surface of the coating up to a position where the average thickness of the coating is 1 / 2, and the portion is located in the recess of the uneven surface of the coating.

10. The adhesive joint structure according to claim 6, wherein, At least a portion of the multiple blocky binary eutectic structures or the multiple blocky ternary eutectic structures are located in the recess of the uneven surface of the coating, extending continuously from the surface of the coating to the Fe-Al interface alloy layer.

11. The adhesive joint structure according to claim 1, wherein, In the average chemical composition of the coating, for Al and Mg, Al: 10.00-25.00%, Mg: 4.50-15.00%.

12. The adhesive joint structure according to claim 1, wherein, In the average chemical composition of the coating, for Al and Mg, Al: 15.00-22.00%, Mg: 5.00-15.00%.

13. The adhesive joint structure according to any one of claims 1, 11, or 12, wherein, In the average chemical composition of the coating, Sn is 0.05% to 0.50%. The coating contains a Mg2Sn phase, which was detected by X-ray diffraction.

14. The adhesive joint structure according to claim 1, claim 11, or claim 12, wherein, The average chemical composition of the coating contains one or both of La and Ce, with the total amount of La and Ce being 0.05 to 0.50%.

15. The adhesive joint structure according to claim 13, wherein, The average chemical composition of the coating contains one or both of La and Ce, with the total amount of La and Ce being 0.05 to 0.50%.

16. The adhesive joint structure according to any one of claims 1 to 4, wherein, The first component and the second component are further joined by a second engagement.

17. The adhesive joint structure according to claim 16, wherein, The second joint is a spot weld.

18. An automotive component comprising an adhesive bonding structure as described in any one of claims 1 to 4 or claims 6 to 12.

19. An automotive component comprising the adhesive bonding structure of claim 5.

20. An automotive component comprising the adhesive bonding structure of claim 13.

21. An automotive component comprising the adhesive bonding structure of claim 14.

22. An automotive component comprising the adhesive bonding structure of claim 15.

23. An automotive component comprising the adhesive bonding structure of claim 16.

24. An automotive component comprising the adhesive bonding structure of claim 17.

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