Method for manufacturing metal components and method for manufacturing metal-resin joints

Abstract

To provide: a metal-resin molded body which has high bonding strength and makes it possible to ensure sufficient airtightness; a metal member for obtaining the metal-resin molded body; and production methods for the metal-resin molded body and the metal member.SOLUTION: Provided is a metal member comprising a metal base material made of metal, and a hydroxyl group-containing film that is formed on the surface of the metal base material and includes a hydroxyl group. When the hydroxyl group-containing film is analyzed by glow discharge optical spectrometry from its surface in a depth direction, the ratio of the amount of the detected hydroxy groups to the total amount of the detected metal in the metal base material and the detected hydroxy groups is 4% or more and 70% or less. Also provided is a metal-resin joined body using the metal member.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] This invention relates to a metal member having a predetermined hydroxyl group-containing coating, a joint between the metal member and a resin molded body, and a method for manufacturing the same. [Background technology]

[0002] In recent years, metal-resin composites, which are formed by integrally joining metal materials such as copper substrates made of copper or copper alloys that have very high heat dissipation and conductivity, or aluminum substrates made of aluminum or aluminum alloys that have high heat dissipation and are lighter than other metals, with resin molded bodies that have high insulating properties, are lightweight and inexpensive, have become widely used in fields such as various sensor components for automobiles, parts for home electrical appliances, and parts for industrial equipment, and their applications are expanding.

[0003] Conventionally, as an industrially suitable method for manufacturing metal-resin joints in which dissimilar materials such as metal materials and resin molded bodies are integrally joined together, a method has been developed in which a metal material is inserted into an injection molding die, molten thermoplastic resin is injected toward the surface of the inserted metal material, and the metal material and the resin molded body are joined at the same time as the resin molded body is formed by injection molding of the thermoplastic resin. Several methods have been proposed to make this process cheaper and to further improve the joint strength.

[0004] For example, according to the present inventors, a technique has been proposed in which an oxygen-containing film is formed on the surface of a metal substrate by performing a specific treatment on the surface of the metal substrate, and a resin molded body is joined via this formed oxygen-containing film (for example, Patent Document 1). This technique is a method that has less risk of corrosion of metal parts and devices, or contamination of the surrounding environment, which was a problem with surface treatment techniques proposed earlier, and can obtain a certain level of bonding strength and airtightness. However, in the method of Patent Document 1, the analysis is limited to electron probe microanalyzer (EPMA) analysis of the oxygen-containing film up to about 3 μm from the outermost layer, or measurement of substances (hydroxyl groups) present in the outermost layer by glow discharge emission spectrometry (GD-OES), and the evaluation of bonding strength and airtightness was not sufficient. Moreover, when using laser light, the laser output for forming the oxygen-containing film on the surface of the aluminum substrate is not described, leaving room for further consideration of the laser treatment conditions. Furthermore, when wet processing is performed to form a hydrated oxide film or a zinc-containing film in order to form an oxygen-containing film, there is concern that certain elements may affect the amount of oxygen (hydroxyl groups) on the surface of the oxygen-containing film, as will be discussed later. Therefore, there was room for further improvement of the processing method.

[0005] On the other hand, several techniques have been proposed in which a metal material is treated to introduce hydroxyl groups into its surface, and then polymer materials or the like are molded onto that treated surface. For example, Patent Document 2 discloses a technique for forming a joint surface between an aluminum die-cast member and a polymer member by irradiating the aluminum die-cast member with a laser to melt the surface layer and form a joint surface, thereby generating hydroxyl groups on the joint surface. It also describes performing plasma treatment (modification process) on the joint surface after melting by laser irradiation to generate even more hydroxyl groups. Furthermore, Patent Document 3 proposes a technique in which a metal hydroxide having hydroxyl groups is formed on the surface of a metal substrate by applying energy, for example by laser treatment, and then a primer containing a predetermined compound is applied to the substrate surface, and the material is joined to another member via the primer layer. [Prior art documents]

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0007] Both Patent Document 2 and Patent Document 3 are technologies for providing hydroxyl groups on the surface of a metal material for adhesion and bonding with a resin component. However, they only consider the presence of hydroxyl groups on the metal surface and do not sufficiently verify the existence state of hydroxyl groups that can contribute to adhesion and bonding with the resin component, and the evaluation regarding bonding strength and airtightness cannot be said to be sufficient.

[0008] An object of the present invention is to provide a metal-resin molded body having high bonding strength and ensuring sufficient airtightness, a metal member for obtaining the same, and a manufacturing method for such a metal-resin molded body and metal member.

Means for Solving the Problems

[0009] That is, the gist of the present invention is as follows. 1 A manufacturing method of a metal member for manufacturing a metal member having a hydroxyl group-containing film containing hydroxyl groups formed on the surface of a metal base material made of metal by a surface treatment, wherein the metal is aluminum or an alloy containing aluminum, the surface treatment is a hot water immersion treatment in which the metal base material is immersed in hot water at 50°C or higher for 60 seconds or longer, and the amount of silicon in the hot water immersion treatment is 0.54 mg / L or more and 2 mg / L or less, ​A method for manufacturing a metal member, characterized in that, in the film formation step, the surface treatment forms a hydroxyl group-containing film such that, when analyzed from the surface in the depth direction by glow discharge emission spectrometry, the ratio of the amount of hydroxyl groups detected to the total amount of the amount of metal detected and the amount of hydroxyl groups detected in the metal substrate is 4% or more and 70% or less. [ 2 In the hot water immersion treatment, the conductivity of the hot water is characterized by being 0.01 mS / m or more and 10 mS / m or less. 1 A method for manufacturing metal components as described in [ ]. [ 3 ] [1] or [2] After obtaining a metal member by the manufacturing method described above, the process then includes a resin molding step in which a resin molded body is bonded to the surface of the obtained metal member. A method for manufacturing a metal-resin joint comprising at least one metal member and at least one resin molded body, A method for manufacturing a metal-resin joint, characterized in that these metal members and the resin molded body are joined via the hydroxyl group-containing film. [ 4 The resin molded article is characterized by containing a thermoplastic resin or a thermosetting resin. 3 A method for manufacturing a metal-resin bond as described in [ ]. [Effects of the Invention]

[0010] The metal member and metal-resin joint of the present invention can improve the bonding strength and airtightness between the metal member and the resin molded body. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic diagram showing the relationship between the laser beam diameter and the irradiation interval. [Figure 2] Figure 2 is a diagram illustrating the overview of joint strength evaluation (1) (shear test). [Figure 3] Figure 3 is a diagram illustrating the overview of joint strength evaluation (2) (shear test). [Figure 4]Figure 4 is a diagram illustrating the overview of the evaluation of the airtightness of a metal-resin joint. [Figure 5] Figure 5 is a diagram illustrating the overview of the evaluation of the airtightness of a metal-resin-metal joint. [Figure 6] Figure 6 is a diagram illustrating the overview of the metal-resin joint used for joint strength evaluation. [Figure 7] Figure 7 is a diagram illustrating the overview of a metal-resin joint used for evaluating airtightness. [Figure 8] Figure 8 is a graph showing the results of surface analysis performed by GD-OES on the metal member fabricated in Example 1 before resin bonding. [Figure 9] Figure 9 shows a cross-section of the metal-resin joint fabricated in Example 1, as observed by SEM (Scanning Electron Microscope). [Figure 10] Figure 10 is a diagram (photograph) for precise cross-sectional evaluation of the joint cross-section of the metal-resin joint fabricated in Example 1, observed using a scanning electron microscope (SEM). [Figure 11] Figure 11 shows a picture (photograph) of the surface of the metal component fabricated in Example 1 before resin bonding, as observed by SEM. [Figure 12] Figure 12 shows the surface of the resin molded body observed by SEM after alkali treatment of the metal-resin joint fabricated in Example 1. [Figure 13] Figure 13 shows the surface of the metal component fabricated in Example 1 before resin bonding, as observed by SEM (Scanning Electron Microscope). [Figure 14] Figure 14 shows the results of cross-sectional mapping performed by EPMA on the metal member fabricated in Example 1 before resin bonding. [Figure 15] Figure 15 shows a cross-section of the metal-resin joint fabricated in Example 2, as observed by SEM (Scanning Electron Microscope). [Figure 16] Figure 16 shows a picture (photograph) of the surface of the metal component fabricated in Example 2 before resin bonding, as observed by SEM. [Figure 17]Figure 17 shows the surface of the resin molded body observed by SEM after alkali treatment of the metal-resin joint fabricated in Example 2. [Figure 18] Figure 18 shows the surface of the metal component fabricated in Example 2 before resin bonding, as observed by SEM (Scanning Electron Microscope). [Figure 19] Figure 19 is a diagram illustrating the outline of the metal-resin-metal joint used for joint strength evaluation in Examples 6 and 19. [Figure 20] Figure 20 is a diagram illustrating the outline of the metal-resin-metal joint used for the evaluation of airtightness in Examples 6 and 19. [Figure 21] Figure 21 shows the surface of the metal component fabricated in Example 15, observed by SEM after hot water immersion treatment and before resin bonding. [Modes for carrying out the invention]

[0012] The metal members and metal-resin joints of the present invention will be described in detail below, along with their manufacturing methods. Some or all of the components of the present invention described below can be combined as appropriate.

[0013] [1. Metal components and metal-resin joints] The metal member of the present invention is a metal member having a bonding surface for bonding with an object to be bonded, and comprises a metal substrate and a hydroxyl group-containing film formed on the surface of the metal substrate. The metal-resin bond of the present invention comprises a metal member and a resin molded body on the surface of the metal member.

[0014] [1-1. Metal Components] <Metal base material> First, the metal base material used in the metal component of the present invention is not limited to copper base material made of copper or copper alloy, iron base material made of iron or iron alloy, aluminum base material made of aluminum or aluminum alloy, etc., and can be determined based on the application of the metal-resin joint formed using it and the various physical properties such as strength, corrosion resistance, and workability required for that application. Also, processed materials obtained by appropriately processing them into a desired shape, and combined materials obtained by appropriately combining these processed materials are also examples. In addition, although it depends on the application, a thickness of about 0.3 mm to 10 mm is usually used. Typically, an oxide film is formed on the surface of the metal base material. The oxide film may be a naturally formed oxide film in the atmosphere, or an anodic oxide film formed by anodizing. It may also be a rolled oxide film formed by hot rolling.

[0015] <Objects to be joined> The object to be joined to the metal substrate is not particularly limited, as long as it is a material that can be joined to the metal substrate. Preferably, the object to be joined is a material that can be joined at a temperature lower than the melting point of the metal substrate. Such an object to be joined is preferably a resin molded body made of a resin material. Resin molded bodies will be described later.

[0016] <Joint surface> A bonding surface is formed on the metal substrate for bonding with the object to be bonded. The bonding surface may be only a part of one surface of the metal substrate, the entire surface, or parts or all of both surfaces; the bonding surface should be formed only in the necessary parts depending on the application. Furthermore, there are no particular limitations on the shape, size, arrangement, etc. of the bonding surface. The same applies to composite materials. In this invention, "bonding surface" refers to the area where bonding between the metal substrate and the resin is planned, and where a predetermined treatment has been applied to the surface of the metal substrate for bonding with the resin. In contrast, the area where the metal substrate and the resin are bonded is referred to as the "jointed area" to distinguish it.

[0017] <Hydroxyl group-containing film> A hydroxyl group-containing film is formed on the bonding surface of the metal substrate. The hydroxyl group-containing film can be formed on a part or the entire bonding surface, but it is preferable to form it on the entire bonding surface in order to ensure sufficient bonding strength and airtightness with the objects to be bonded. "The entire bonding surface" does not necessarily mean that only 100% of the surface area of ​​the bonding surface is covered, and does not exclude cases where there are very small spots on the surface that are not covered by the hydroxyl group-containing film. Preferably, 90% or more, and more preferably 95% or more, of the bonding surface is covered by the hydroxyl group-containing film. The hydroxyl group-containing film can be formed on the surface of the metal substrate by subjecting it to a laser treatment or hot water immersion treatment, which will be described later.

[0018] Hydroxyl group-containing coatings can be identified by detecting hydroxyl groups near the surface of a metal component using glow discharge optical emission spectrometry (GD-OES). Specifically, first, GD-OES is used to measure the emission intensity (V) originating from the main metal and hydroxyl groups constituting the metal substrate in the thickness direction at the bonding surface of the metal component. Next, the amount of main metal constituting the metal substrate is calculated from the integrated value (area) of emission intensity originating from the main metal. The amount of hydroxyl groups is also measured from the integrated value of emission intensity originating from the hydroxyl groups. Furthermore, the ratio of the amount of hydroxyl groups to the total amount of detected main metal and hydroxyl groups is calculated as the hydroxyl group abundance. In the emission spectrum obtained by GD-OES, the peaks appearing at 281 nm and 309 nm are considered to be the peaks originating from hydroxyl groups. For measuring the emission intensity near the surface of the metal component using GD-OES, measurements should be performed up to a depth of 200 nm from the surface. Specifically, the measurement range is measured from the detection of the emission intensity derived from the main metal elements and hydroxyl groups constituting the metal substrate until the time required for 200 nm sputtering corresponding to the main metal elements has elapsed. This measurement range (time) can be determined by pre-measuring the sputtering rate (μm / min) of a standard sample containing the main metal elements to be measured in high purity. By measuring the emission intensity using GD-OES, it is possible to detect and evaluate not only the components present on the outermost surface of the metal component, but also components present to a certain depth that can contribute to bonding with the resin.

[0019] The hydroxyl group content should be between 4% and 70%. When the hydroxyl group content is above the lower limit, the number of hydroxyl groups present near the surface of the metal component increases, and the interaction with the functional groups contained in the resin molded body is strengthened, which tends to improve the airtightness of the metal-resin joint. At the same time, the bonding strength of the metal-resin joint also tends to improve. The lower limit is preferably 5% or more, more preferably 6% or more, and even more preferably 7% or more. Furthermore, ensuring that the hydroxyl group content is below the aforementioned upper limit prevents excessive laser treatment or hot water immersion treatment of the metal substrate, as described later, and prevents the mechanical strength of the formed hydroxyl group-containing film from becoming excessively weak, thereby preventing a decrease in the airtightness and bonding strength of the metal-resin joint. The aforementioned upper limit is preferably 60% or less, more preferably 50% or less, and even more preferably 40% or less.

[0020] The hydroxyl group content varies depending on the method of hydroxyl group formation. For example, it tends to be higher when a metal substrate is subjected to hot water immersion treatment compared to when the metal substrate is subjected to laser treatment. When a hydroxyl group-containing film is formed by laser treatment, the hydroxyl group content is preferably 5% or more, more preferably 6% or more, even more preferably 7% or more, preferably 30% or less, more preferably 20% or less, even more preferably 15% or less, and particularly preferably 10% or less. When a hydroxyl group-containing film is formed by hot water immersion treatment, the hydroxyl group content is preferably 10% or more, more preferably 30% or more, even more preferably 40% or more. Preferably 60% or less, more preferably 55% or less, and even more preferably 50% or less.

[0021] The hydroxyl group-containing film contains, depending on the metal constituting the metal substrate, a hydroxide (metal hydroxide) of the metal constituting the metal substrate, such as aluminum hydroxide (Al(OH)3), aluminum oxide hydroxide (AlO(OH)), copper hydroxide (Cu(OH)2), iron(II) hydroxide (Fe(OH)2), iron(III) oxide hydroxide (FeO(OH)), or a hydroxide (metal oxide) of the metal constituting the metal substrate. Furthermore, the hydroxyl group-containing film may also contain an oxide (metal oxide) of the metal constituting the metal substrate, such as aluminum oxide (Al2O3), copper(I) oxide (Cu2O), copper(II) oxide (CuO), iron(II) oxide (FeO), iron(II,III) oxide (Fe3O4), or iron(III) oxide (Fe2O3), depending on the metal constituting the metal substrate.

[0022] When a hydroxyl group-containing film is formed by the laser treatment described later, it is generally preferable to form micro-order-sized uneven surfaces (hereinafter sometimes referred to as "macro-uneven surfaces") in which recesses and protrusions are formed alternately in a continuous manner. Furthermore, the hydroxyl group-containing film has nano-order-sized fine uneven surfaces (hereinafter sometimes referred to as "fine uneven surfaces") on its surface. When the surface of a metal substrate is treated by laser irradiation, a deposit of metal oxide formed due to the laser irradiation is accumulated around the irradiated area, forming a film-like structure. This molten metal layer, consisting of such deposits, contains oxygen as a metal oxide as described above. Such a molten metal layer has a hydroxyl group-containing film with hydroxyl groups on its outermost layer and is covered with the macro-uneven surfaces and the hydroxyl group-containing film having fine uneven surfaces.

[0023] When a hydroxyl group-containing film is formed by the hot water immersion treatment described later, a three-dimensional structure with bumps and depressions on the order of nanometers is formed. The bumps spread in a mesh-like pattern on the surface of the metal substrate (aluminum substrate), and the depressions are regions sandwiched between the bumps. Each region surrounded by the bumps is approximately tens to 100 nm in size. The three-dimensional structure with bumps can be confirmed by observing the surface or cross-section of the metal component, for example, using a scanning electron microscope (SEM). The three-dimensional structure with bumps contributes to improving the bonding strength and adhesion between the aluminum substrate and the resin.

[0024] <Macro uneven area> The macro-relief portions of the hydroxyl group-containing film formed by laser irradiation are structures having a micrometer-order size and are formed on the surface of the hydroxyl group-containing film. As described above, the macro-relief portions have a structure consisting of depressions created by perforation of the metal substrate by laser irradiation and protrusions made of metal oxide deposits created by laser irradiation. Furthermore, by performing multiple laser irradiations adjacent to each other, a repeating structure consisting of depressions and protrusions is created. The macro-relief portions can be confirmed by observing the surface or cross-section of the metal member, for example, using a scanning electron microscope (SEM). The macro-relief portions, like the hydroxyl group-containing film, contain metal hydroxides or metal oxide hydroxides. In addition, the macro-relief portions, like the hydroxyl group-containing film, may also contain metal oxides.

[0025] The macro-relief portion has a predetermined opening diameter (D) and depth (L), which can be determined, for example, by the procedure described with reference to Figures 9 and 15. Furthermore, depending on these opening diameter (D) and depth (L), the macro-relief portion has a predetermined aspect ratio (L / D). The macro-relief portion, like the hydroxyl group-containing film, contains a metal hydroxide or a metal oxide hydroxide. The macro-relief portion may also contain a metal oxide, similar to the hydroxyl group-containing film.

[0026] To calculate the aperture diameter (D) and depth (L), a scanning electron microscope (SEM) is used to observe the joint cross-section of the metal member or metal-resin joint, and a cross-sectional photograph is taken that includes multiple uneven surfaces formed by laser irradiation, where at least 12 recesses and 11 protrusions are arranged alternately in a continuous pattern. The aperture diameter (D) and depth (L) can then be calculated from the multiple uneven surfaces included in this cross-sectional photograph.

[0027] Specifically, as shown in Figures 9 and 15, the depth is determined by adding the following lines to the cross-sectional photograph. First, in the aforementioned cross-sectional photograph, for 12 arbitrarily selected consecutive recesses, the deepest recess Pb1 is defined as the deepest bottom of each recess. A reference line RL1 is drawn that passes through the lowest recess Pb1 or a position lower than Pb1, and also passes through the position where the sum of the distances from the deepest points of each recess is smallest. Next, in the aforementioned cross-sectional photograph, the highest convex part among the convex parts sandwiched between the 12 recesses is defined as the highest convex part Pt1. A reference line RL2 is drawn that passes through the highest convex part Pt1 and is parallel to the reference line RL1. In this way, by drawing RL1 and RL2 so that they pass through the lowest recess Pb1 and the highest convex part Pt1, respectively, it is possible to prevent the depth L from being calculated to be excessively large or small compared to the actual value, thus preventing the aspect ratio from being calculated to be large or small. Next, in the cross-sectional photograph described above, for the 12 consecutive recesses including the lowest recess Pb1, 12 straight lines are drawn from the bottom of each recess in a direction perpendicular to the reference line RL2, and these lines are designated as lines a to l (shown as dashed lines in Figures 9 and 15).

[0028] For the lines a to l described above, parallel median lines are drawn between adjacent lines, and these median lines are designated as lines A to K in order. The distance between lines A and B is obtained as the opening diameter D1 of the recess sandwiched between lines A and B, through which line b passes. Similarly, the distances between adjacent lines A to K are obtained as opening diameters D1 to D10. Furthermore, for each of lines b to k, the distance from the bottom of each recess to the reference line RL2 is obtained as the depths L1 to L10 of the 10 recesses. The opening diameters D1 to D10 and depths L1 to L10 correspond to the opening diameters D and depths L of the 10 recesses through which lines b to k, excluding the two ends a and l, pass.

[0029] In this way, the depths L1 to L10 and the aperture diameters D1 to D10 can be obtained for the 10 recesses through which lines b to k, respectively, are included in the cross-sectional photograph described above. Furthermore, outliers are detected from among the depths L1 to L10 and aperture diameters D1 to D10 using the Smirnov-Grubbs test. To detect outliers, first, for the 10 recesses with depths L1 to L10, the absolute deviation is calculated by subtracting the value of each depth L from the mean value of depths L1 to L10, and the test statistic t is calculated by dividing the calculated absolute deviation by the unbiased standard deviation of depths L1 to L10. Next, the p-value, which represents the probability that the test statistic t is that value, is found. Then, values ​​with a p-value of less than 5% are detected as outliers. If an outlier is detected, the depth L of the recess in which the outlier was detected is excluded from the 10 recesses with depths L1 to L10, and outlier detection is performed again for the depth L of the remaining recesses, and this is repeated until no more outliers are detected. Outliers are detected from the aperture diameters D1 to D10 in the same way. Furthermore, for the 10 recesses through which lines b to k in the aforementioned cross-sectional photographs pass, the average depth L and average opening diameter D are calculated from the depth L and opening diameter D of the remaining recesses, excluding those where outliers were detected in either the depth L or the opening diameter D, or both. The average depth L and average opening diameter D obtained in this way are defined as the depth (L) and opening diameter (D) of the metal member or metal-resin joint.

[0030] Furthermore, for the 10 recesses through which lines b to k in the aforementioned cross-sectional photographs pass, the aspect ratio (L / D) of each recess is calculated by dividing the depth L of the remaining recess by the opening diameter D of the recess, excluding the recesses where outliers were detected in either the depth L or the opening diameter D, or both. Then, the average of the aspect ratios (L / D) of multiple recesses is calculated from the aspect ratio (L / D) of each individual recess. The average of the aspect ratios (L / D) obtained in this way is taken as the aspect ratio (L / D) of the metal member or metal-resin joint.

[0031] In the present invention, the opening diameter (D) is preferably 20 μm to 200 μm, more preferably 40 μm to 180 μm, even more preferably 60 μm to 150 μm, and particularly preferably 80 μm to 120 μm. When the opening diameter (D) is greater than or equal to the lower limit, the recess becomes wider, making it easier for the resin to be bonded to enter the recess and also making it easier to satisfy the aspect ratio described later. On the other hand, when the opening diameter (D) is less than or equal to the upper limit, the fitting effect due to the entry of the resin is more easily achieved and it is also easier to satisfy the aspect ratio described later.

[0032] In the present invention, the depth (L) is preferably 20 μm to 200 μm, more preferably 40 μm to 180 μm, even more preferably 60 μm to 150 μm, and particularly preferably 80 μm to 120 μm. When the depth (L) is greater than or equal to the lower limit, sufficient depth is achieved, making it easier for the fitting effect due to resin penetration to be realized and for the aspect ratio described later to be satisfied. On the other hand, when the depth (L) is less than or equal to the upper limit, the formation of a coarse uneven structure due to both the depth (L) value and the opening diameter (D) becoming large is prevented, making it easier for the fitting effect due to resin penetration to be realized and for the aspect ratio described later to be satisfied.

[0033] In this invention, the aspect ratio (L / D) of the opening diameter (D) to the depth (L) is preferably 0.5 to 5, more preferably 0.5 to 4, even more preferably 0.7 to 3, and particularly preferably 1 to 2. By satisfying this aspect ratio, the resin flows into the depth of the recess, suppressing the generation of voids between the macro-recessed portion and the resin, sealing the entire surface of the hydroxyl group-containing film, and increasing the surface area of ​​the hydroxyl group-containing film that interacts with the resin. In this way, the shape of the recess allows the interaction between the metal member and the resin to be fully exhibited, thereby improving the bonding strength and airtightness between the metal member and the resin molded body. When L / D exceeds the above lower limit, the depth of the recess is not too small relative to the opening diameter, resulting in a recess with an appropriate depth, which makes it easier for the interaction between the metal member and the resin to be exhibited when the resin flows into the recess. Furthermore, by keeping the aspect ratio below the upper limit mentioned above, the depth of the recess becomes relatively small compared to the opening diameter, resulting in a roughly triangular shape where the width of the recess gradually narrows from the opening to the depth, making it easier for the resin to flow into the depths of the recess.

[0034] <Minute unevenness> As described above, the surface of the hydroxyl group-containing film has fine irregularities. These fine irregularities are structures with an irregular shape on the order of nanometers and are formed on the macroscopic irregularities on the surface of the hydroxyl group-containing film. The fine irregularities are formed on the surface of the hydroxyl group-containing film when a metal molten layer having the hydroxyl group-containing film is formed by laser irradiation. The fine irregularities can be confirmed by observing the surface or cross-section of the metal member, for example, using a scanning electron microscope.

[0035] The micro-textured areas have nano-sized openings ranging from 10 nm to 50 nm, and a fine structure with a film thickness of 10 nm to 1000 nm. When observed by SEM, the micro-textured areas are observed as spongy structures with the aforementioned sizes of openings. The micro-textured areas, like hydroxyl group-containing films, contain metal hydroxides or metal oxide hydroxides. Furthermore, the micro-textured areas, like hydroxyl group-containing films, may also contain metal oxides.

[0036] According to the inventors' verification, it was confirmed that the resin penetrates into macroscopic and microscopic uneven areas, or that the chemical bonding between the hydroxyl groups of the hydroxyl group-containing film and the functional groups in the resin contributes to ensuring bonding strength and airtightness. Although there are still some unclear points regarding this, as confirmed in the examples described below (Examples 1 and 2), the effectiveness of the presence of the hydroxyl group-containing film (microscopic uneven areas) can be confirmed by verifying i) chromic acid treatment or ii) stearic acid treatment on a metal member on which a hydroxyl group-containing film has been formed. The mechanism is as follows: i) The dissolution rate of aluminum substrates in an aqueous solution of chromic acid phosphate is slower than that of aluminum oxide. By treating the metal member with a chromium phosphate hydroxyl solution, the aluminum oxide on the outermost layer can be selectively dissolved, leaving the aluminum substrate as the outermost layer after treatment. At this time, the microscopic uneven structure of the hydroxyl group-containing film disappears, and the hydroxyl groups on the surface also disappear. Furthermore, ii) Stearic acid has a hydrophilic carboxyl group (-COOH) and a hydrophobic alkyl group (-C 17 H 35 It possesses the properties of forming a monomolecular film with the thickness of one molecule, combining the properties of ) and . When a metal component is treated with stearic acid, the hydroxyl groups present on the surface of the hydroxyl group-containing film interact (hydrogen bond) with the COOH groups of stearic acid, and the surface of the hydroxyl group-containing film is covered with the hydrophobic groups of stearic acid. As a result, the shape of the micro-irregularities is maintained, but the activity of the hydroxyl groups present on the surface of the micro-irregularities is eliminated.

[0037] [1-2. Resin molded products] Next, a resin molded body suitable for use as a bonding target for a metal member having a predetermined bonding surface will be described. The resin molded body can be formed by molding a resin composition onto the surface of a metal member. The resin molded body contains a thermoplastic resin or a thermosetting resin.

[0038] As thermoplastic resins, they can be appropriately selected from known resins depending on the application. Examples include polyamide resins (aliphatic polyamides such as PA6 and PA66, aromatic polyamides), polystyrene, copolymers containing styrene units such as ABS resin and AS resin, polyethylene, copolymers containing ethylene units, polypropylene, copolymers containing propylene units, other polyolefins, polyvinyl chloride, polyvinylidene chloride, polycarbonate resins, acrylic resins, methacrylic resins, polyester resins, polyacetal resins, and polyphenylene sulfide resins. These can be used individually or in combination of two or more. Among these, polyamide resins and polyphenylene sulfide resins are preferred due to their high fluidity during resin molding and their ability to easily penetrate into recesses.

[0039] Thermosetting resins can be appropriately selected from known types depending on the application, but examples include urea resin, melamine resin, phenol resin, resorcinol resin, epoxy resin, polyurethane, and vinyl urethane, and these can be used one or more types. Among these, reaction-curing adhesives are preferable to use epoxy resins, acrylic resins, or urethane resins because they have good compatibility with hydroxyl group-containing films and high bonding strength can be obtained as the reaction area increases.

[0040] Furthermore, an adhesive can be used as the resin molded article. As the adhesive, a compound containing the above-mentioned thermoplastic resin or thermosetting resin, or other elastomer or rubber, that exhibits adhesive properties can be used. As the adhesive, it can be appropriately selected from known adhesives depending on the application. For example, as a dry-solidifying adhesive, examples include acrylic resin emulsion type, rubber latex type, vinyl acetate resin solvent type, vinyl copolymer resin solvent type, and rubber solvent type. As a reaction-curing adhesive, examples include epoxy resin type, urethane resin type, and modified silicone resin type, and these can be used one or more of them. Among these, reaction-curing adhesives are preferable to use epoxy resin type, acrylic resin type, or urethane resin type because they have good compatibility with hydroxyl group-containing films and high bonding strength can be obtained as the reaction area increases.

[0041] Furthermore, thermoplastic elastomers can be used, such as styrene elastomers, vinyl chloride elastomers, olefin elastomers, urethane elastomers, polyester elastomers, nitrile elastomers, and polyamide elastomers, and these can be used one or more of them.

[0042] Furthermore, in order to further improve the performance of each of the above resins (resin compositions), fillers such as fibrous, granular, or plate-like materials, as well as various elastomer components, can be added. This includes the adhesion to metal components, mechanical strength, heat resistance, dimensional stability (resistance to deformation, warping, etc.), and electrical properties.

[0043] Furthermore, the resin (resin composition) may contain known additives that are generally added, namely flame retardants, colorants such as dyes and pigments, stabilizers such as antioxidants and ultraviolet absorbers, plasticizers, lubricants, release agents, crystallization accelerators, crystal nucleating agents, etc., as appropriate, within limits that do not impede the required performance or the objectives of the present invention.

[0044] [1-3. Metal-resin bonded body] In a metal-resin joint, a metal member and a resin molded body are integrally joined via a hydroxyl group-containing film formed on the joining surface. Preferably, the resin is molded in a state where it penetrates into the macroscopic and microscopic irregularities formed in the hydroxyl group-containing film. The joining may be performed using one metal member and one resin molded body, or multiple sets of either or both may be used, or even multiple sets of these may be arbitrarily laminated. The configuration can be appropriately determined depending on the application.

[0045] For example, the metal-resin joint may be a metal-resin joint in which a metal member and a resin molded body are joined in a laminated or continuous arrangement. Alternatively, the metal-resin joint may be a metal-resin-metal joint in which a metal member, a resin molded body, and a metal member are joined in a laminated or continuous arrangement in that order. Alternatively, the metal-resin joint may be a resin-metal-resin joint in which a resin molded body, a metal member, and a resin molded body are joined in a laminated or continuous arrangement in that order.

[0046] If the metal-resin joint is a metal-resin-metal joint that joins two or more metal members via a resin molded body, it may include a resin molded body formed by molding a thermoplastic resin or thermosetting resin while sandwiched between the metal members. Alternatively, the metal members may be joined via the adhesive, using an adhesive containing a thermoplastic resin or thermosetting resin as the resin molded body.

[0047] [2. Method for manufacturing metal components and metal-resin joints] The present invention provides a method for manufacturing a metal member having a hydroxyl group-containing film on its surface (joining surface), comprising a film formation step of forming a hydroxyl group-containing film by surface treatment on the surface of a metal substrate. The present invention also provides a method for manufacturing a metal-resin bond, comprising a resin molding step of bonding a resin molded body to the surface of a metal member.

[0048] [2-1. Method for manufacturing metal components] <Preparation process> The present invention's method for manufacturing a metal component may include a preparatory step prior to the film formation step, in which the surface of the metal substrate is pretreated by blasting, degreasing, etching, desmatting, chemical polishing, and electropolishing.

[0049] <Film formation process> The surface treatment in the film formation process of the present invention involves either irradiating the surface of the metal substrate prepared as described above with laser light (hereinafter simply referred to as "laser treatment," etc.) or immersing the metal substrate prepared as described above in hot water at 50°C or higher for 60 seconds or more (hereinafter simply referred to as "hot water immersion treatment," etc.). Each of these treatments will be described below.

[0050] <2-1-1. Laser Processing> A hydroxyl group-containing film is formed on the bonding surface with the object to be bonded by laser processing to obtain the metal member according to the present invention. Here, known lasers can be used as the laser, but it is preferable to use a pulsed-oscillation laser because it is advantageous for spot processing of the metal substrate as in the present invention. For example, a YAG laser, YVO4 laser, semiconductor laser, or fiber laser can be used.

[0051] The principle of hydroxyl group-containing film formation is generally as follows: The energy from laser irradiation melts and evaporates the metal substrate. The evaporation creates pores, which become the basis for recesses, and the areas on both sides (adjacent sides) of these recesses that are not irradiated by the laser become the basis for protrusions. At the same time, some or all of the molten metal is oxidized to become a metal oxide, and metal oxides have at least some degree of partial ionicity. Metal ions (Al) are present on the new surface of the metal oxide. 3+ ) and oxide ions (O 2-A hydroxyl group is present. Due to electrostatic neutralization, the metal oxide present on the surface of the molten metal layer reacts with moisture in the air, causing hydroxylation, and the surface of the molten metal layer becomes covered with hydroxyl groups. In this way, a hydroxyl group-containing film is formed on the outermost layer of the molten metal layer. During this process, the metal oxide is deposited around the irradiated area, which becomes a depression, forming a convex portion. The deposits made of metal oxide cover the depressions and convex portions, forming a film-like structure. Thus, a hydroxyl group-containing film is formed by deposits made of metal oxide formed on the surface of the metal substrate. In addition, a molten metal layer is formed on the hydroxyl group-containing film that creates the uneven shape of the macro-relief portion.

[0052] Furthermore, if there are areas on the metal component that have not been irradiated with the laser, there is no molten metal layer in these areas, nor is there a hydroxyl group-containing film. Normally, an oxide film is formed in the areas that have not been irradiated with the laser. Since the areas that have not been irradiated with the laser do not have a hydroxyl group-containing film, the effect of improving airtightness due to chemical bonding caused by hydroxyl groups may be reduced. Also, if the areas that have not been irradiated with the laser are flat, the effect of improving bonding strength due to mechanical bonding caused by macroscopic irregularities may be reduced. Therefore, if areas that have not been irradiated with the laser remain on the bonding surface and a hydroxyl group-containing film is not formed over the entire bonding surface, the effect of improving airtightness and bonding strength of the metal-resin bond may be reduced. For this reason, it is preferable that the hydroxyl group-containing film is formed over the entire bonding surface of the metal substrate so that there are no areas that have not been irradiated with the laser.

[0053] <Laser processing conditions> In order to obtain the hydroxyl group-containing coating described above, it is preferable to set the laser processing conditions to take the following points into consideration.

[0054] Laser processing is affected by the irradiation energy of the laser beam per unit area (hereinafter also referred to as "energy density"). Energy density represents the laser power received per unit area and per unit time by the laser-irradiated area of ​​the object (workpiece) being laser-treated. Energy density (J / mm 2 The laser beam output W (W), the number of laser beam scans N (times), the laser beam irradiation interval C (mm), the laser beam scanning speed V (mm / s), the length perpendicular to the laser beam irradiation direction in the laser-irradiated area, and the width parallel to the laser beam irradiation direction in the laser-irradiated area are expressed by the following formula (A1). Energy density = (((Length / C) × Width × N) / V) × W) / (Length × Width) ... Equation (A1) By rearranging equation (A1), we obtain the following equation (A2). The energy density can be calculated using equation (A2). Energy density = (W × N) / (C × V) ... Equation (A2)

[0055] The energy density is preferably 0.4 J / mm². 2 The above explains the process. As the energy density increases, a hydroxyl group-containing film with a predetermined hydroxyl group abundance is more likely to form on the surface of the laser-treated metal component. Furthermore, fine irregularities containing hydroxyl groups are more likely to form. In addition, as the energy density increases, the depressions in the macro-irregularities formed on the surface of the metal substrate become deeper, and the surface roughness of the metal component after laser treatment tends to increase. Note that the higher the melting point and the greater the thermal diffusion of the metal constituting the metal substrate, the less susceptible the metal substrate is to the effects of laser light. Considering the above circumstances, it is desirable to change the energy density according to the metal being laser-treated.

[0056] When performing laser processing on a metal substrate with aluminum as the main metal, the energy density is preferably 0.4 J / mm². 2 More preferably 0.6 J / mm 2Above, more preferably 1 J / mm 2 Above, particularly preferably 1.3 J / mm 2 Above. When performing laser treatment on a metal substrate mainly made of aluminum, the energy density is preferably 5 J / mm 2 Below, more preferably 4 J / mm 2 Below, further preferably 3 J / mm 2 Below, particularly preferably 2 J / mm 2 Below.

[0057] When performing laser treatment on a metal substrate mainly made of iron, the energy density is preferably 0.4 J / mm 2 Above, more preferably 1 J / mm 2 Above, further preferably 2 J / mm 2 Above, particularly preferably 3 J / mm 2 Above. When performing laser treatment on a metal substrate mainly made of iron, the energy density is preferably 10 J / mm 2 Below, more preferably 8 J / mm 2 Below, further preferably 7 J / mm 2 Below, particularly preferably 5 J / mm<00> 2 Below.

[0058] When performing laser treatment on a metal substrate mainly made of copper, the energy density is preferably 0.4 J / mm 2 Above, more preferably 1 J / mm 2 Above, further preferably 3 J / mm 2 Above, particularly preferably 5 J / mm 2 Above. When performing laser treatment on a metal substrate mainly made of copper, the energy density is preferably 30 J / mm 2 Below, more preferably 20 J / mm 2 Below, further preferably 15 J / mm 2 Below, particularly preferably 10 J / mm 2 Below.

[0059] When the energy density is above the lower limit, a hydroxyl group-containing film with a predetermined hydroxyl group abundance is more easily formed on the surface of the laser-treated metal component. Furthermore, fine irregularities containing hydroxyl groups are more easily formed. Therefore, the hydroxyl group-containing film (and fine irregularities) improve the airtightness and bonding strength of the metal-resin joint. Additionally, when the energy density is below the upper limit, the hydroxyl group abundance in the hydroxyl group-containing film formed on the metal substrate surface does not become too high, preventing a decrease in the mechanical strength of the hydroxyl group-containing film.

[0060] The laser conditions (laser processing conditions) in laser processing should be set appropriately to achieve the energy density described above. Parameters for laser processing conditions include the laser output (W), laser frequency (kHz), laser beam diameter (μm), laser irradiation interval (μm), laser scanning speed (mm / s), and number of laser scans (times). The number of scans refers to the number of times the laser beam is repeatedly irradiated along the same irradiation trajectory. Here, the relationship between the laser beam diameter and irradiation interval will be explained with reference to Figure 1. The laser irradiation interval refers to the distance between the trajectory 4 of one laser beam irradiated onto the object and the trajectory 4' of another laser beam irradiated adjacent to that laser. More specifically, the laser irradiation interval refers to the distance between one end of the trajectory 4 of the one laser beam in the direction perpendicular to the scanning direction 1 and the end of the trajectory 4' of the other laser beam on the same side as the one laser beam. When a pulsed laser is irradiated, the laser beam trajectory is represented as a continuous trajectory of pores formed by individual laser pulses. In this case, the laser beam irradiation interval 3 corresponds to the sum of the width of the region sandwiched between the laser beam trajectories formed by the continuous pores and the size of the beam diameter 2. Table 1 shows examples of laser processing conditions when the main metal of the metal substrate to be laser-treated is aluminum, iron, or copper.

[0061] [Table 1]

[0062] <2-1-2. Hot water immersion treatment> Furthermore, a hydroxyl group-containing film is formed on the bonding surface with the object to be joined by hot water immersion treatment to obtain the metal member according to the present invention.

[0063] The principle of forming a hydroxyl group-containing film by hot water immersion treatment is generally as follows: For example, when a metal substrate with aluminum as the main metal is immersed in hot water at 50°C or higher, the aluminum reacts with the hot water to form a hydroxyl group-containing film containing aluminum hydroxide (AlO(OH)). There are no restrictions on the metal substrate used in the hot water immersion treatment, but it is preferable to use aluminum or an alloy containing aluminum in order to form a hydroxyl group-containing film having the desired hydroxyl group abundance.

[0064] <Conditions for immersion in hot water> In order to obtain the hydroxyl group-containing coating described above, it is preferable to set the hot water immersion conditions taking the following points into consideration. Even when performing the hot water immersion treatment, a preparatory step may be included in which the metal substrate surface is pretreated by blasting, degreasing, etching, desmatting, chemical polishing, and electropolishing. For the degreasing treatment, a dry treatment using a laser or ozone may be performed, or a wet treatment using an acid or alkali may be performed. Furthermore, one of these pretreatments may be performed, or two or more treatments may be performed in combination. Among these, blasting, which involves spraying a projectile, is preferred as a pretreatment because it increases the surface area by increasing the surface irregularities and surface roughness of the metal substrate, thereby allowing a relatively large amount of hydroxyl groups to be present during the hot water immersion treatment. Furthermore, blasting may be combined with other pretreatments, and it is preferable to perform other pretreatments after blasting. Known methods can be used for blasting.

[0065] The temperature of the hot water should be 50°C or higher. Preferably, it should be 60°C or higher, more preferably 90°C or higher, and even more preferably 95°C or higher. By setting the temperature to 50°C or higher, the above reaction can occur, and it becomes possible to produce a hydroxyl group-containing film that satisfies the above hydroxyl group abundance. There is no upper limit to the temperature, but from the viewpoint of avoiding excessive reaction, it is more preferable to set it to 100°C or lower.

[0066] Furthermore, the immersion time in warm water should be 60 seconds or more. Preferably, it should be 5 minutes or more, and more preferably 10 minutes or more. By immersing for 60 seconds or more, the above reaction can occur, and it becomes possible to form a hydroxyl group-containing film that satisfies the above hydroxyl group abundance. There is no upper limit to the immersion time, but from the viewpoint of avoiding excessive reaction and the formation of a thick hydroxyl group-containing film that becomes brittle and reduces bonding strength, it is preferable to set it to 60 minutes or less, more preferably 30 minutes or less, and even more preferably 20 minutes or less.

[0067] Furthermore, the hot water used should contain a silicon (Si) (silicon ion) content of 2 milligrams / liter (mg / L) or less. Preferably, it should be 1 mg / L or less, more preferably 0.5 mg / L or less, and even more preferably 0.25 mg / L or less. It is most preferable to keep the silicon content as low as possible, and it is preferable to use deionized water or pure water with a silicon content within this range. The reason for the effectiveness of keeping the silicon content in the hot water below a predetermined amount is not entirely clear, but it is thought that if silicon exceeds the predetermined amount, the formation of hydroxyl groups is inhibited during the formation process of the hydroxyl group-containing film, thus hindering the formation of the hydroxyl group-containing film. Also, if the reaction is carried out for a long time with silicon exceeding the predetermined amount, even if a hydroxyl group-containing film is formed, it will be a brittle film. Therefore, in order to keep the hydroxyl group abundance of the hydroxyl group-containing film within the above range, the silicon content in the hot water should be below the above upper limit.

[0068] Furthermore, regarding the hot water used, in addition to having the silicon content specified above, it is preferable that the conductivity of the hot water is 0.01 mS / m or more and 10 mS / m or more. Since a conductivity of less than 0.01 mS / m of hot water falls into the realm of ultrapure water, it should be set to be above the above lower limit, taking into consideration the cost of pure production and practicality. A more preferable lower limit is 0.02 mS / m or more, and an even more preferable lower limit is 0.05 mS / m or more. In addition, in order to slow down the film formation rate of the hydroxyl group-containing film and to reduce the occurrence of defects in the film, the conductivity should be below the above upper limit. A more preferable upper limit is 5 mS / m or less, and an even more preferable upper limit is 2 mS / m or less.

[0069] [2-2. Method for manufacturing metal-resin bonded bodies] Metal-resin composites are manufactured by using a resin composition as a raw material and forming a resin molded body on the surface of a metal component.

[0070] Here, as for the method of molding the resin composition (forming the resin molded body), a suitable molding method can be adopted depending on the resin used. For example, when using a thermoplastic resin, one can obtain a metal-resin joint by integrally joining a resin molded body to a metal member by injection molding a composition containing the thermoplastic resin onto the metal member, or one can obtain a resin molded body in advance by injection molding and then integrally join the obtained resin molded body to the metal member surface by thermocompression bonding using means such as laser welding, vibration welding, ultrasonic welding, hot press welding, hot plate welding, non-contact hot plate welding, or high-frequency welding, but is not limited to these.

[0071] Furthermore, when using a thermosetting resin, for example, one could obtain a metal-resin joint by integrally joining a resin molded body by injection molding a composition containing a thermosetting resin onto a metal member, or by compression molding by applying a composition adjusted to a predetermined viscosity onto a metal member and then integrally heating and pressurizing it. However, the method is not limited to these.

[0072] Furthermore, when using an adhesive, it can be applied to the metal component and allowed to dry and harden. However, heating or other operations may be performed as needed, and molding conditions suitable for the adhesive being used can be adopted.

[0073] [3. Effects and Benefits] Conventionally, to increase the bonding strength of metal-resin joints, it has been considered effective to create a structure that facilitates mechanical interaction by forming uneven surfaces with predetermined aperture diameters and depths when metal materials are treated with laser light, thereby allowing resin to penetrate. Furthermore, it was known that the molten portion of the metal substrate produced by this laser treatment is an oxygen-containing film, and that this oxygen-containing film contributes to the development of bonding strength. In addition, there are documents that disclose laser irradiation density and irradiation intensity, but because these documents do not provide a definitive definition, the laser treatment conditions that can improve bonding strength and airtightness have not been clarified.

[0074] As a result of detailed investigations by the inventors, they found that in order to obtain a metal-resin joint that increases the bonding strength of the metal-resin molded body and ensures sufficient airtightness, it is necessary for the metal member and the resin molded body to be bonded via a predetermined hydroxyl group-containing film at the bonding surface. Specifically, by measuring the luminescence intensity of hydroxyl groups present on the surface of the hydroxyl group-containing film using GD-OES, they were able to detect and evaluate not only the components present on the outermost layer of the metal member, but also components present to a certain depth that can contribute to bonding with the resin. They concluded that defining the hydroxyl group abundance evaluated in this way within a predetermined range is effective in improving the chemical bonding between the hydroxyl groups of the hydroxyl group-containing film and the functional groups in the resin. From this perspective, they found that by forming a predetermined hydroxyl group-containing film on the surface of the metal substrate, when bonded to a resin molded body, a metal-resin molded body with high bonding strength and sufficient airtightness can be obtained.

[0075] In the metal member and metal-resin joint of the present invention, a hydroxyl group-containing film is formed on the joint surface, wherein the hydroxyl group abundance, as evaluated by GD-OES analysis from the surface toward the depth direction, is 4% to 70%. Having such a hydroxyl group-containing film allows for chemical bonding through hydrogen bonding between the hydroxyl groups present on the surface of the metal member and the functional groups present on the surface of the resin molded body. Furthermore, because the hydroxyl group-containing film has macro-protrusions on the order of μm, mechanical bonding (anchor effect) can be expected between the macro-protrusions and the resin molded body. In addition, the hydroxyl group-containing film has fine protrusions on the order of nm on the surface of the macro-protrusions. This increases the surface area of ​​the hydroxyl group-containing film presented on the joint surface, and is expected to increase the amount of hydroxyl groups interacting with the resin molded body. As a result, the metal member and metal-resin joint of the present invention enhance the chemical and mechanical bonding effects between the metal member and the resin molded body, improving joint strength and airtightness.

[0076] The present invention provides a method for manufacturing metal members and metal-resin joints, comprising a film formation step in which a hydroxyl group-containing film having a predetermined hydroxyl group abundance, as evaluated by the GD-OES method, is formed by surface treatment of a metal substrate. When laser treatment is performed as the surface treatment, the energy density in the laser treatment is 0.4 J / mm². 2 This concludes the explanation. Furthermore, the energy density of the present invention represents the laser output received per unit area and per unit time by the laser-irradiated portion to which the laser light is irradiated, and is calculated using the laser light output W, the number of laser light scans N, as well as the laser light irradiation interval C and the laser light scanning speed V. This makes it easier to form the hydroxyl group-containing film, and makes it possible to improve the bonding strength and airtightness between the metal member and the resin molded body. Furthermore, when performing hot water immersion treatment as a surface treatment, using aluminum or an aluminum-containing alloy as the metal substrate and immersing it in hot water with a silicon content of 2 mg / L or less and a temperature of 50°C or higher for 60 seconds or more makes it easier to form the desired hydroxyl group-containing film, thereby improving the bonding strength and airtightness between the metal member and the resin molded body. [Examples]

[0077] Preferred embodiments of the present invention will be specifically described below based on examples, comparative examples, and test examples, but the present invention shall not be construed as being limited thereto. In addition, Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, Examples 12, 13, 14, 15, 16, and 17 are for reference only.

[0078] [Evaluation Method] <Evaluation of joint strength (1) (shear test)> The joint strength of the metal-resin joint was evaluated by measuring the shear strength in accordance with ISO 19095. Specifically, as shown in Figure 2, the metal-resin joint 7, which consists of a metal member 6 and a resin molded body 5, was fixed to a dedicated jig 8, and a load was applied at a speed of 10 mm / min so that a shear force was applied in a direction parallel to the joint surface, and a test was conducted to break the joint between the metal member and the resin molded body. The breaking force when the metal-resin joint broke was determined as the tensile shear strength (MPa).

[0079] Furthermore, the fracture surface of the metal component after the shear test was visually observed to confirm the fracture morphology. When the base material fracture occurred in the resin molded body, it was judged as resin base material fracture (○) (good). On the other hand, partial resin base material fracture (△) or fracture occurring at the interface between the metal component and the resin molded body (×) was judged as poor. If a fracture was observed between the metal component and the resin joint when the resin molded body was demolded from the mold after injection molding, the shear strength was set to 0 MPa.

[0080] <Evaluation of joint strength (2) (shear test)> The joint strength of the metal-resin-metal joint was evaluated by measuring the shear strength in accordance with JIS K 6850. Specifically, as shown in Figure 3, a metal-resin-metal joint 9, formed by bonding two metal members 6 and 6' using a thermosetting adhesive described later, was fixed to a dedicated jig 8. A load was applied at a speed of 5 mm / min so that a shear force was applied in a direction parallel to the joint surface, and a test was conducted to break the joint portion of the metal members connected by the adhesive. The breaking force when the metal-resin-metal joint broke was determined as the tensile shear strength (MPa).

[0081] Furthermore, the fracture surface was visually observed after the shear strength evaluation to confirm the fracture morphology. If cohesive failure occurred in the adhesive and adhesive remained throughout the joint, it was judged as resin matrix failure (○) (good). If interfacial failure occurred between the aluminum plate (metal plate) and the adhesive (×), it was judged as poor.

[0082] <Evaluation of airtightness> The airtightness of the metal-resin joint or the metal-resin-metal joint was evaluated by an air leak test. Specifically, as shown in Fig. 4, with the metal-resin joint 7, which is formed by joining the metal member 6 and the resin molded body 5, clamped and fixed to the dedicated airtightness jig 13, air was applied at a maximum positive pressure of 0.5 MPa and held for 1 minute. Then, the presence or absence of air leakage was visually confirmed. Alternatively, as shown in Fig. 5, with the metal-resin-metal joint 9, which is formed by bonding two metal members 6 and 6' using a thermosetting adhesive described later, clamped and fixed to the dedicated airtightness jig 13, air was applied at a maximum positive pressure of 0.5 MPa and held for 1 minute. Then, the presence or absence of air leakage was visually confirmed. In the dedicated airtightness jig 13 described above, the metal-resin joint 7 or the metal-resin-metal joint 9 is sandwiched and fixed from above and below with an O-ring 11 interposed. With the metal-resin joint 7 or the metal-resin-metal joint 9 sandwiched, water 10 exists in the upper open part of the dedicated airtightness jig 13, and air exists in the lower sealed part of the dedicated airtightness jig 13. By applying air to the sealed part through the air vent tube 12, it is possible to confirm whether air leaks to the open part side through the metal-resin joint 7 or the metal-resin-metal joint 9 by using as a mechanism whether bubbles are generated from the bonding interface. When there was no air leak within the evaluation time, it was evaluated as "qualified (good)", and when an air leak was observed, it was evaluated as "unqualified (bad)".

[0083] <GD-OES surface analysis> Surface analysis was performed on metal components before joining resin molded parts using a glow discharge optical emission spectrometer (GD-OES) (Horiba, Ltd.: GD-Profiler2). The measurement conditions were: analysis diameter (anode diameter): 4 mmφ, gas pressure: 600 Pa, RF output: 35 W, acquisition interval: 0.1 s, measured elements: Al (measurement wavelength 396.157 nm, high voltage of photomultiplier tube 600 V), measured elements: Fe (measurement wavelength 374.954 nm), measured elements: Cu (measurement wavelength 324.759 nm), measured elements: OH group (measurement wavelength 306.775 nm, high voltage of photomultiplier tube 900 V). Furthermore, the measurement method involved sputtering the sample with Ar plasma and performing elemental analysis by causing atomic emission from the sputtered atoms. The hydroxyl group abundance was calculated from the emission intensity detected in the range from the detection of the metal component or hydroxyl group until the time required for 200 nm sputtering corresponding to the main elements constituting the metal component (Al, Cu, Fe) had elapsed. The time required for 200 nm sputtering was determined by pre-measuring each standard sample containing the above elements in high purity (Al: A995 from Nippon Light Metal Co., Ltd., Cu: Cu-113514 from Niraco Co., Ltd., Fe: Fe-223469 from Niraco Co., Ltd.) using the same apparatus and analytical conditions as above, and obtaining the resulting sputtering rate (μm / min). The purity of each standard sample, as well as the sputtering rate and the time required for 200 nm sputtering for each standard sample, are shown in Table 2 below.

[0084] [Table 2]

[0085] <Evaluation of the joint surface> Before joining the resin molded body, the metal component or the metal-resin joint was cut in the thickness direction, embedded in epoxy resin, and then wet polished to prepare a sample for joint cross-sectional evaluation. The thickness direction cross-section of the joint cross-sectional evaluation sample was observed at a magnification of 100 to 500 times using a scanning electron microscope (JEOL, JSM-7200F). From the observed cross-section, the depth (L) and aperture diameter (D) of the macro-relief were measured, and the aspect ratio (L / D) was calculated. In addition, the joint cross-sectional evaluation sample before joining the resin molded body was cut in the thickness direction, and a sample for precision cross-sectional evaluation was prepared using a cross-section polisher (JEOL, SM-09010). The thickness direction cross-section of the precision cross-sectional evaluation sample was observed at a magnification of 50,000 times using a scanning electron microscope (JEOL, JSM-7200F).

[0086] <Evaluation of the surface of metal components before joining> The surface of the metal component before joining the resin molded body was observed using a scanning electron microscope (JEOL, JSM-7200F) at a magnification of 50,000x.

[0087] <Evaluation of bonding interfaces by alkaline treatment> A metal-resin composite with aluminum as the main metal was subjected to an alkaline treatment by immersing it in a 5 wt% sodium hydroxide solution at 50°C for 12 hours to completely dissolve the metal and obtain a test resin molded body. Alkali treatment can dissolve and remove the metal components of a metal-resin composite, leaving the resin molded body intact. The surface of the test resin molded body, after alkali treatment, was observed at a magnification of 50,000x using a scanning electron microscope (JEOL, JSM-7200F).

[0088] <Evaluation of hydroxyl group-containing coatings obtained by chromium phosphate treatment> The metal members (aluminum plate material, aluminum disk) before resin bonding were subjected to chromic phosphate acid treatment by immersing them in a chromic phosphate aqueous solution prepared by adding distilled water to 35 mL of phosphoric acid and 20 g of chromium (VI) oxide to make 1 L at 95°C to 100°C for 10 minutes, thereby obtaining test metal members. In this example, by the chromic phosphate acid treatment, the hydroxyl groups present on the surface of the fine concavo-convex portions and the hydroxyl group-containing film were removed, and the treatment was performed under the condition that the macro concavo-convex portions remained without being melted away. Next, a resin molded body was bonded to the test metal member after the chromic phosphate acid treatment by the bonding method of the resin molded body described later, thereby producing a test bonded body after the chromic phosphate acid treatment. The bonding strength and airtightness of the test bonded body after the chromic phosphate acid treatment were evaluated by the evaluation method described above. Also, the surfaces of the metal member before the chromic phosphate acid treatment and the test metal member after the chromic phosphate acid treatment were observed using a scanning electron microscope (manufactured by JEOL, JSM-7200F).

[0089] <Evaluation of Hydroxyl Group-Containing Film by Stearic Acid Treatment> Stearic acid treatment was performed by volatilizing stearic acid powder in an electric furnace maintained at 100°C and exposing the metal members (aluminum plate material, aluminum disk) before resin bonding therein for 24 hours, thereby obtaining test metal members. Next, a resin molded body was bonded to the test metal member after the stearic acid treatment by the bonding method of the resin molded body described later, thereby producing a test bonded body after the stearic acid treatment. The bonding strength and airtightness of the test bonded body after the stearic acid treatment were evaluated by the evaluation method described above.

[0090] <EPMA Cross-Section Mapping> Cross-sectional mapping was performed on metal components before joining resin molded parts using an Electron Probe Microanalyzer (EPMA) (Shimadzu Corporation: EPMA-1610). The measurement conditions were a mapping analysis with an irradiation diameter of 40 μm / step and 512 steps each in the longitudinal and transverse directions. The measurement area was 20.48 mm × 20.48 mm, the sampling time per step was 20 ms, the acceleration voltage was 15 kV, and the oxygen depth resolution was 3 μm or less. Next, the detected oxygen intensity was calculated as a weight percentage (wt%) from a pre-prepared calibration curve. The calibration curve used was created by calculating the oxygen intensity of an Al2O3 standard sample (oxygen content: 48 wt%) and the oxygen intensity of high-purity Al foil.

[0091] <Ion concentration in hot water> The concentrations of each cation and each anion were measured in the hot water used for the hot water immersion treatment according to the following methods 1) to 5). 1) Si The Si ion concentration in hot water was determined according to the molybdenum blue spectrophotometric method of JIS K 0101. The absorbance at a wavelength of λ=810 nm was measured using a spectrophotometer, and the concentration of ionic silica (mg / L) was calculated from a calibration curve of silica standard solutions prepared in advance.

[0092] 2)B, Mg, Ca, Fe, Ni, Al, Zn The concentrations of boron (B), magnesium (Mg), calcium (Ca), iron (Fe), nickel (Ni), aluminum (Al), and zinc (Zn) ions in hot water were determined according to ICP emission spectrometry. The sample solution (hot water) and calibration curve solutions containing standard solutions of each element were introduced into a high-frequency inductively coupled plasma. The emission intensity at the emission wavelengths for each element was measured, and the concentrations of each ion in the hot water were calculated from the calibration curves created by adding the standard solutions of each element. The emission wavelengths are as follows. B:249.773nm Mg: 279.553nm Al: 396.152nm Ca: 393.366nm Fe: 238.204nm Zn: 213.856nm Ni: 231.604nm

[0093] 3) Na, K The ion concentrations of sodium (Na) and potassium (K) in hot water were determined using flame atomic absorption spectrometry. The sample solution (hot water) and calibration curve solutions containing standard solutions for each element were sprayed onto an acetylene-air flame. A hollow cathode lamp, which emits light at wavelengths specific to each element (Na: 589.0 nm, K: 766.5 nm), was used as the light source. The amount of light absorbed by each atomized element was measured, and the ion concentrations of Na and K in the hot water were calculated from the calibration curves created by adding the standard solutions for each element.

[0094] 4) Li The lithium (Li) ion concentration in hot water was determined according to the flame photometric method. The sample solution (hot water) and a calibration curve solution containing a standard solution of element Li were sprayed onto an acetylene-air flame, and the brightness of the emission line spectrum (Li: 670.8 nm) of the excited and emitted element was measured. The Li ion concentration in the hot water was then calculated from the calibration curve containing the standard solution of element Li.

[0095] 5) F, Cl, NO2, Br, NO3, SO4, PO4 The concentrations of fluorine (F), chlorine (Cl), nitrite (NO2), bromine (Br), nitric acid (NO3), sulfuric acid (SO4), and phosphoric acid (PO4) ions in hot water were determined according to ion chromatography. The sample solution (hot water) and calibration curve solutions containing standard solutions for each ion were introduced into the apparatus, the ions were separated using a separation column, and the electrical conductivity of each ion was measured using an electrical conductivity detector. The concentrations of each ion in the hot water were then calculated from the calibration curves containing the standard solutions for each ion.

[0096] [Example 1] <Fabrication of metal components> In accordance with ISO 19095, a rectangular aluminum plate measuring 1.5 mm thick x 18 mm wide x 45 mm long, and an annular aluminum disc measuring 2 mm thick x outer diameter Φ55 mm x inner diameter Φ20 mm were cut from a hollow extruded A6063 aluminum alloy (A6063-T5) treated with the temper symbol T5 as shown in JIS H0001, and prepared as metal base materials.

[0097] Next, laser treatment was performed on the workpiece surfaces of these aluminum plates and aluminum discs under the following conditions to form a hydroxyl group-containing film on the surface and create a bonding surface with the resin molded body. For the aluminum plates, the laser was irradiated in a striped pattern over a rectangular area measuring 10 mm in the longitudinal direction and 18 mm in the transverse direction at one of the longitudinal ends of the main surface. For the aluminum discs, the laser was irradiated from the inside in a concentric circular area with a width of 2.0 mm. The laser treatment conditions are summarized in Table 5 below. <Laser processing conditions> • Equipment: Keyence Corporation, 3-axis fiber laser marker (Model: MDF-5200) • Laser wavelength: 1090nm • Transmission method: pulse Output: 42.5W • Frequency: 60kHz Beam diameter: 60 μm • Irradiation interval: 90 μm • Scanning speed: 320 mm / s • Number of scans (number of irradiations): 1 • Energy density: 1.48 J / mm² 2

[0098] <Joining of resin molded bodies, fabrication of metal-resin joints> As described above, each metal component (aluminum plate and aluminum disc after laser treatment), on which a hydroxyl group-containing film was formed on its surface to create a bonding surface, was inserted into a mold manufactured in accordance with ISO 19095 using an injection molding machine (Nissei Plastic Industrial Co., Ltd., FNX1103-18A). These components were then injection molded using aromatic nylon (Mitsubishi Engineering Plastics Co., Ltd., product name: Reny®, grade: XL1002U) with polyamide MXD10 as the base resin as the thermoplastic resin, at a resin temperature of 250°C, a mold temperature of 140°C, an injection speed of 30 mm / s, and a holding pressure of 80 MPa. As a result, a bonded body (metal-resin bonded body 7, Figure 6) of an aluminum plate (metal component) 6 and a resin molded body 5 was produced, with a rectangular shape of 3 mm thickness × 10 mm width × 45 mm length, and a bonding area of ​​5 mm × 10 mm at the rectangular joint between the aluminum plate and the resin molded body. Furthermore, the resin molded body is a disc shape with a thickness of 2 mm and a diameter of 24 mm, and the joining width of the annular joint with the inner diameter side surface of the aluminum disc is 2.0 mm, and the joining area is 138.2 mm². 2 A joint (metal-resin joint 7, Figure 7) was fabricated, consisting of an aluminum disc (metal component) 6 and a resin molded body 5.

[0099] <Rating> First, surface analysis was performed using GD-OES. The results of the GD-OES measurements are shown in Figure 8. From the GD-OES measurements, within the range from the detection of emission intensity originating from aluminum and hydroxyl groups until the 3.33 seconds required for 200 nm sputtering, the detected amount of aluminum was 39.7 and the detected amount of hydroxyl groups was 3.6. The hydroxyl group abundance was calculated to be 8.31%. The hydroxyl group abundance is shown in Table 7.

[0100] Furthermore, the joint cross-section of the metal-resin joint was evaluated. The results of cross-sectional observation by SEM are shown in Figure 9. Specifically, for the 12 consecutive recesses shown in Figure 9, the third recess from the right, marked with a white dashed line c as described later, was designated as the lowest recess Pb1, and a reference line RL1 was drawn passing through Pb1. Also, the convex portion through which the white solid line H passes, as described later, was designated as the highest convex portion Pt1, and a reference line RL2 was drawn passing through Pt1 and parallel to RL1. Furthermore, straight lines were drawn from the lowest part of each of the 12 recesses in a direction perpendicular to RL2, and these are indicated by dashed lines a to l. Then, parallel median lines were drawn between adjacent dashed lines a to l, and these are indicated by solid lines A to K. Finally, the measured values ​​of depth L1 to L10 and opening diameter D1 to D10 were obtained as shown in the figure. The measured values ​​are shown in Tables 3 and 4 below. Next, the Smirnov-Grubbs test was performed on the obtained measurements using the procedure described above to detect outliers. As shown in Table 4, the p-value for aperture diameter D10 was 0.022 (2.2%), so D10 was excluded. The same test was then performed again on D1 to D9 after exclusion, and no outliers were detected. Therefore, the average values ​​of L1 to L9 and D1 to D9, excluding the recess corresponding to the outlier D10, were taken as the depth (L) and aperture diameter (D) in Example 1, respectively, and the aspect ratio (L / D) was calculated. As a result, the depth (L) was 143.0 μm, the aperture diameter (D) was 88.2 μm, and the aspect ratio (L / D) was 1.6.

[0101] [Table 3]

[0102] [Table 4]

[0103] Furthermore, Figure 10 shows the observation results for precise cross-sectional evaluation of the cross-section using SEM. Furthermore, the surface of the metal component before joining was evaluated against the laser-treated metal component. The observation results of the surface of the laser-treated metal component are shown in Figure 11. Furthermore, the bonding interface of the metal-resin bond was evaluated by alkali treatment. The observation results of the surface of the resin molded body after alkali treatment are shown in Figure 12. Furthermore, the hydroxyl group-containing coating obtained by chromic acid phosphate treatment was evaluated on the metal components before resin bonding. Figure 13 shows the surface observation results of the metal components after chromic acid phosphate treatment using SEM. Table 8 shows the evaluation results of bonding strength and airtightness before and after chromic acid phosphate treatment. Furthermore, the hydroxyl group-containing coating obtained by stearic acid exposure treatment was evaluated on metal components before resin bonding. Table 8 shows the evaluation results of bonding strength and airtightness before and after stearic acid treatment. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7. Furthermore, cross-sectional mapping was performed using EPMA. The EPMA measurement results are shown in Figure 14.

[0104] [Example 2] As the metal, we used A5052 aluminum alloy (A5052-H34) treated with the tempering symbol H34 as specified in JIS H0001. The laser processing conditions were: output power 50W, irradiation interval 110μm, scanning speed 400mm / s, and energy density 1.14J / mm². 2 Except for the changes made, metal components (aluminum plate material, aluminum disc) were manufactured in the same manner as in Example 1, and each metal-resin composite body for evaluation was also manufactured. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint cross-section of the metal-resin joint was evaluated. The results of cross-sectional observation by SEM are shown in Figure 15. The evaluation was performed using the same method as in Example 1, and L1-10 and D1-10 were measured and the Smirnov-Grubbs test was performed, but no outliers were detected. Therefore, the average values ​​of L1-L10 and D1-D10 were taken as the depth (L) and aperture diameter (D) in Example 2, respectively, and the aspect ratio (L / D) was calculated. As a result, the depth (L) was 126.0 μm, the aperture diameter (D) was 114.0 μm, and the aspect ratio (L / D) was 1.1. Furthermore, the surface of the metal component before joining was evaluated against the laser-treated metal component. The observation results of the surface of the laser-treated metal component are shown in Figure 16. Furthermore, the bonding interface of the metal-resin bond was evaluated by alkali treatment. The observation results of the surface of the resin molded body after alkali treatment are shown in Figure 17. Furthermore, the hydroxyl group-containing coating obtained by chromic acid phosphate treatment was evaluated on the metal components before resin bonding. Table 8 shows the evaluation results of bonding strength and airtightness before and after chromic acid phosphate treatment. Figure 18 shows the surface observation results of the metal components after chromic acid phosphate treatment using SEM. Furthermore, the hydroxyl group-containing coating obtained by stearic acid exposure treatment was evaluated on metal components before resin bonding. Table 8 shows the evaluation results of bonding strength and airtightness before and after stearic acid treatment. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0105] [Example 3] As the metal, we used A5052 aluminum alloy (A5052-H34) treated with the tempering symbol H34 as shown in JIS H0001. The laser processing conditions were a scanning speed of 340 mm / s and an energy density of 1.45 J / mm². 2 This was changed. Otherwise, the metal components (aluminum plate material, aluminum disc) were prepared in the same manner as in Example 1.

[0106] Next, the laser-treated aluminum plate and aluminum disc were inserted into molds manufactured in accordance with ISO 19095 using an injection molding machine (Nissei Plastic Industrial Co., Ltd., FNX1103-18A). Then, these were injection molded using polyphenylene sulfide (PPS) (Polyplastics Co., Ltd., product name: Duraphide, grade: 1150MF1) as the thermoplastic resin at a resin temperature of 320°C, a mold temperature of 150°C, an injection speed of 30 mm / s, and a holding pressure of 80 MPa. As a result, a joint (metal-resin joint 7, Figure 6) was produced, consisting of an aluminum plate (metal component) 6 and a resin molded body 5, with a rectangular shape of 3 mm thickness × 10 mm width × 45 mm length, and a joint area of ​​5 mm × 10 mm at the rectangular joint between the aluminum plate and the resin molded body. Furthermore, the resin molded body is a disc shape with a thickness of 2 mm and a diameter of 24 mm, and the joining width of the annular joint with the inner diameter side surface of the aluminum disc is 2.0 mm, and the joining area is 138.2 mm². 2 A joint (metal-resin joint 7, Figure 7) was fabricated, consisting of an aluminum disc (metal component) 6 and a resin molded body 5. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0107] [Example 4] The laser processing conditions were: output power of 35W and energy density of 1.18J / mm². 2 Except for the changes made, metal components (aluminum plate material, aluminum disc) were manufactured in the same manner as in Example 3, and each metal-resin composite body for evaluation was also manufactured. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0108] [Example 5] The laser processing conditions were: output power of 15W and energy density of 0.51J / mm². 2Except for the changes made, metal components (aluminum plate material, aluminum disc) were manufactured in the same manner as in Example 3, and each metal-resin composite body for evaluation was also manufactured. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0109] [Comparative Example 1] The laser processing conditions were: output power of 5W and energy density of 0.17J / mm². 2 Except for the changes made, metal components (aluminum plate material, aluminum disc) were manufactured in the same manner as in Example 3, and each metal-resin composite body for evaluation was also manufactured. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0110] [Comparative Example 2] Similar metal substrates (aluminum plate material, aluminum disc) as in Example 1 were prepared, but laser treatment was not performed. Similar to Example 3, an attempt was made to fabricate each metal-resin composite for evaluation, but the resin did not bond with the metal component, and it was not possible to fabricate a metal-resin composite. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7.

[0111] [Example 6] Two rectangular aluminum plates measuring 5 mm thick x 25 mm wide x 50 mm long, a circular aluminum disc measuring 2 mm thick x Φ55 mm outer diameter x Φ20 mm inner diameter, and a circular aluminum disc measuring 2 mm thick x Φ24 mm outer diameter were cut out from a hollow extruded A5052 aluminum alloy (A5052-H34) treated with the tempering symbol H34 specified in JIS H0001, and prepared as metal base materials.

[0112] Next, regarding the laser processing conditions, the scanning speed is 500 mm / s and the energy density is 0.99 J / mm². 2 Except for the change, the laser irradiation was performed under the same conditions as in Example 3. For the two aluminum plates, the laser was applied in a striped pattern to a rectangular area of ​​6 mm x 25 mm at the longitudinal end of one of the main surfaces. For the annular aluminum disc, the laser was applied concentrically from the inside to an annular area with a width of 2.0 mm. For the circular aluminum disc, the laser was applied concentrically from the outer edge to an area with a width of 2.0 mm.

[0113] A thermosetting adhesive (one-component heat-curing epoxy adhesive) (manufactured by 3M Japan Ltd., product name: Scotch-Weld® SW2214) was applied to the aluminum plate and aluminum disc after laser processing, using a SUS wire to adjust the adhesive thickness to 0.2 mm and then applied to the bonding surface. After applying the adhesive, the two aluminum plates were bonded together, and under bonding conditions of applying a pressure of 0.01 MPa and heating for 30 minutes after the test piece temperature reached 150°C, a bonded structure (a joint between an aluminum plate, a resin molded body, and an aluminum plate) (metal-resin-metal joint 9, Figure 19) was fabricated, in which the bonding area of ​​the rectangular joint between the two aluminum plates was 6 mm × 25 mm. Furthermore, after applying the adhesive, the annular aluminum disc and the circular aluminum disc were bonded together, and under the same bonding conditions, the bonding width of the annular joint between the annular aluminum disc and the circular aluminum disc was 2.0 mm, and the bonding area was 138.2 mm². 2 A joint (metal-resin-metal joint 9, Figure 20) was fabricated by connecting an annular aluminum disc (metal member) 6 and a circular aluminum disc (metal member) 6' via an adhesive. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0114] [Comparative Example 3] The laser irradiation was performed using a Miyachi Technos ML-7112A laser marker. The specifications of the device were: Q-switched pulse, wavelength 1064 nm, maximum output 7 W, beam diameter 50-60 μm. The laser conditions were: output 100%, irradiation interval 50 μm, scanning speed 500 mm / s, frequency 10 kHz, number of scans 1, energy density 0.30 J / mm². 2 Laser irradiation was performed under the specified conditions. Otherwise, metal components (aluminum plate material, aluminum disc) were fabricated in the same manner as in Example 3, and each metal-resin composite body for evaluation was also fabricated. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0115] [Comparative Example 4] As the metal, rolled oxygen-free copper (C1020) as specified in JIS H3100 was used, and a rectangular copper plate with a thickness of 1.5 mm, a width of 18 mm, and a length of 45 mm, and an annular copper disc with a thickness of 2 mm, an outer diameter of Φ55 mm, and an inner diameter of Φ20 mm were cut out and prepared as metal substrates, in the same dimensions as in Example 3, but laser treatment was not performed. Otherwise, attempts were made to fabricate each metal-resin joint for evaluation in the same manner as in Example 3, but the resin did not bond with the metal members, and it was not possible to fabricate a metal-resin joint. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7.

[0116] [Example 7] Similar to Comparative Example 4, using rolled oxygen-free copper (C1020) as specified in JIS H3100, a rectangular copper plate measuring 1.5 mm thick x 18 mm wide x 45 mm long and an annular copper disc measuring 2 mm thick x Φ55 mm outer diameter x Φ20 mm inner diameter were cut out and prepared as metal base materials. Next, regarding the laser processing conditions, the scanning speed was set to 200 mm / s and the energy density to 2.47 J / mm². 2Except for the change, metal components (copper plate material, copper disc) were fabricated by laser irradiation in the same manner as in Example 3, and each metal-resin composite body for evaluation was also fabricated. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0117] [Example 8] The laser processing conditions were: scanning speed of 400 mm / s, number of scans (number of irradiations) of 5, and energy density of 6.21 J / mm². 2 Except for the change, metal components (copper plate material, copper disc) were fabricated by laser irradiation in the same manner as in Example 7, and each metal-resin composite body for evaluation was also fabricated. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0118] [Comparative Example 5] The laser processing conditions were: output power 35W, scanning speed 400mm / s, number of scans (number of irradiations) 1, and energy density 0.32J / mm². 2 Except for the change, metal components (copper plate material, copper disc) were fabricated by laser irradiation in the same manner as in Example 7, and each metal-resin composite body for evaluation was also fabricated. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0119] [Comparative Example 6] Using stainless steel sheet material (SUS304) as the metal, a rectangular iron plate material with a thickness of 1.5 mm, a width of 18 mm, and a length of 45 mm, and an annular iron disc with a thickness of 2 mm, an outer diameter of Φ55 mm, and an inner diameter of Φ20 mm were cut out and prepared as metal base materials, similar to the dimensions in Example 3, but laser treatment was not performed. Otherwise, attempts were made to fabricate each metal-resin joint for evaluation in the same manner as in Example 3, but the resin did not bond with the metal members, and it was not possible to fabricate a metal-resin joint. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7.

[0120] [Example 9] Similar to Comparative Example 6, stainless steel sheet metal (SUS304) was used as the metal, and a rectangular iron plate measuring 1.5 mm thick x 18 mm wide x 45 mm long, and an annular iron disc measuring 2 mm thick x Φ55 mm outer diameter x Φ20 mm inner diameter were cut out and prepared as metal base materials. Next, metal components (iron plates and iron discs) were fabricated by laser processing under the same conditions as in Example 3, and each metal-resin composite body was also fabricated for evaluation. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0121] [Example 10] The laser processing conditions included a scan count (number of irradiations) of 2 and an energy density of 2.91 J / mm². 2 Except for the change, metal components (iron plates, iron discs) were fabricated by laser irradiation in the same manner as in Example 9, and each metal-resin composite body for evaluation was also fabricated. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0122] [Example 11] The laser processing conditions included a scan count (number of irradiations) of 3 and an energy density of 4.37 J / mm². 2 Except for the change, metal components (iron plates, iron discs) were fabricated by laser irradiation in the same manner as in Example 9, and each metal-resin composite body for evaluation was also fabricated. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0123] [Example 12] <Fabrication of metal components> In accordance with ISO 19095, a rectangular aluminum plate measuring 1.5 mm thick x 18 mm wide x 45 mm long and an annular aluminum disc measuring 2 mm thick x outer diameter Φ55 mm x inner diameter Φ20 mm were cut from a hollow extruded A5052 aluminum alloy (A5052-H34) treated with the tempering symbol H34 as shown in JIS H0001, and prepared as metal base materials.

[0124] Next, each of the aluminum plates and aluminum discs was subjected to the following treatments: first, degreasing by immersion in a 30 wt% nitric acid aqueous solution at room temperature for 1 minute; second, etching by immersion in a 5 wt% sodium hydroxide aqueous solution at 50°C for 1 minute; and third, desmatting by immersion in a 30 wt% nitric acid aqueous solution at room temperature for 1 minute. After that, they were thoroughly washed with deionized water with a conductivity of 0.27 mS / m, and then subjected to a hot water immersion treatment by immersion in 95°C hot water with the same conductivity of 0.27 mS / m for 1 minute to form a hydroxyl group-containing film on the surface. The Si ion concentration in the hot water was measured using a spectrophotometer at a wavelength of λ=810 nm, according to the molybdenum blue spectrophotometric method of JIS K 0101, and the concentration of ionic silica (mg / L) was calculated from a calibration curve of silica standard solutions prepared in advance, and was found to be 0.1 mg / L or less. These hot water immersion treatment conditions are summarized in Table 6 below. Furthermore, the concentrations of cations and anions in the hot water used are summarized in Tables 9 and 10 below.

[0125] <Joining of resin molded bodies, fabrication of metal-resin joints> As described above, each metal component (aluminum plate and aluminum disc after hot water immersion treatment), which had a hydroxyl group-containing film formed and a joint surface formed, was inserted into a mold manufactured in accordance with ISO 19095 using an injection molding machine (Nissei Plastic Industrial Co., Ltd., FNX1103-18A). Then, polyphenylene sulfide (PPS) (Polyplastics Co., Ltd., product name: Duraphide, grade: 1150MF1) was used as the thermoplastic resin and injection molded at a resin temperature of 320°C, a mold temperature of 150°C, an injection speed of 30 mm / s, and a holding pressure of 80 MPa. As a result, a joint (metal-resin joint 7, Figure 6) of an aluminum plate (metal component) 6 and a resin molded body 5 was produced, with a rectangular shape of 3 mm thickness × 10 mm width × 45 mm length and a joint area of ​​5 mm × 10 mm at the rectangular joint between the aluminum plate and the resin molded body. Furthermore, the resin molded body is a disc shape with a thickness of 2 mm and a diameter of 24 mm, and the joining width of the annular joint with the inner diameter side surface of the aluminum disc is 2.0 mm, and the joining area is 138.2 mm². 2 A joint (metal-resin joint 7, Figure 7) was fabricated, consisting of an aluminum disc (metal component) 6 and a resin molded body 5. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0126] [Example 13] Except for changing the hot water immersion time to 5 minutes, the hot water immersion treatment was performed in the same manner as in Example 12 to produce metal components (aluminum plate material, aluminum disc), and each metal-resin composite body for evaluation was also produced. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the surface of the metal components was evaluated before joining, based on the hot water immersion treatment. The results of the surface observation of the metal components after the hot water immersion treatment are shown in Figure 21. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0127] [Comparative Example 7] Except for the hot water immersion treatment, which involved adding tap water to deionized water to adjust the Si ion concentration to 2.2 mg / L and the conductivity to 1.45 mS / m, and immersing the materials in this 95°C hot water for 5 minutes, the hot water immersion treatment was performed in the same manner as in Example 12 to produce metal components (aluminum plates and aluminum discs), and to produce each metal-resin composite for evaluation. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0128] [Example 14] Similar to Example 12, an aluminum plate and an aluminum disc were prepared as metal substrates. Next, as a pretreatment, a manual air blasting device was used on the respective workpiece surfaces, and a polygonal white fused alumina (grit: #80, particle size: 150-180 μm) was used as the abrasive material. This was sprayed at a pressure of 0.1 MPa for approximately 5 seconds. Subsequently, degreasing, etching, and desmatting treatments were performed in the same manner as in Example 12. After that, metal components (aluminum plate and aluminum disc) were manufactured by hot water immersion treatment in the same manner as in Example 12, except that the hot water immersion time was changed to 5 minutes, using the same hot water (ion-exchanged water) as in Example 12. In addition, each metal-resin bond for evaluation was manufactured. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0129] [Example 15] Except for the hot water immersion treatment, which involved adding a sulfuric acid aqueous solution to ion-exchanged water to adjust the Si ion concentration to 0.1 mg / L or less and the conductivity to 1.68 mS / m, and immersing the materials in 95°C hot water for 5 minutes, the same hot water immersion treatment was performed as in Example 12 to produce metal components (aluminum plates and aluminum discs), and to produce each metal-resin composite for evaluation. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0130] [Example 16] Except for the hot water immersion treatment, which involved immersing the materials in 60°C hot water for 10 minutes, the same hot water immersion treatment was performed as in Example 12 to produce metal components (aluminum plates and aluminum discs), and each metal-resin composite for evaluation was also produced. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0131] [Comparative Example 8] Except for the hot water immersion treatment, which involved adding tap water to deionized water to adjust the Si ion concentration to 2.9 mg / L and the conductivity to 1.51 mS / m, and immersing the materials in this 60°C hot water for 10 minutes, the hot water immersion treatment was performed in the same manner as in Example 12 to produce metal components (aluminum plates and aluminum discs), and to produce each metal-resin composite for evaluation. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0132] [Example 17] Two rectangular aluminum plates measuring 5 mm thick x 25 mm wide x 50 mm long, a circular aluminum disc measuring 2 mm thick x Φ55 mm outer diameter x Φ20 mm inner diameter, and a circular aluminum disc measuring 2 mm thick x Φ24 mm outer diameter were cut out from a hollow extruded A5052 aluminum alloy (A5052-H34) treated with the tempering symbol H34 specified in JIS H0001, and prepared as metal base materials.

[0133] Next, a hot water immersion treatment was performed in the same manner as in Example 12, except that the metal substrate was immersed in 95°C hot water for 5 minutes, to form a hydroxyl group-containing film on the surface of the metal substrate and to produce metal components (aluminum plate material, aluminum disc).

[0134] For each metal component (aluminum plate material and aluminum disc after hot water immersion treatment), a thermosetting adhesive (one-component heat-curing epoxy adhesive) (manufactured by 3M Japan Ltd., product name: Scotch-Weld® SW2214) was used as the resin and applied to the joint surface, adjusting the thickness of the adhesive with a SUS wire to 0.2 mm. After applying the adhesive, the two aluminum plates were bonded together and bonded under bonding conditions of 0.01 MPa pressure, with the test piece temperature reaching 150°C and then heated for 30 minutes. A bonded body of aluminum plates (metal components) 6 and 6' (a joint of aluminum plate material, resin molded body, and aluminum plate material) (metal-resin-metal joint 9, Figure 19) was fabricated with the rectangular joint area of ​​the two aluminum plates measuring 6 mm × 25 mm. Furthermore, after applying the adhesive, the annular aluminum disc and the circular aluminum disc were bonded together, and under the same bonding conditions, the bonding width of the annular joint between the annular aluminum disc and the circular aluminum disc was 2.0 mm, and the bonding area was 138.2 mm². 2 A joint (metal-resin-metal joint 9, Figure 20) was fabricated by connecting an annular aluminum disc (metal member) 6 and a circular aluminum disc (metal member) 6' via an adhesive. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0135] [Example 18] Except for the hot water immersion treatment, which involved adding sodium metasilicate (Na2SiO3) to ion-exchanged water to adjust the Si ion concentration to 0.54 mg / L and the conductivity to 0.29 mS / m, and immersing the materials in this 95°C hot water for 5 minutes, the hot water immersion treatment was performed in the same manner as in Example 12 to produce metal components (aluminum plates and aluminum discs), and to produce each metal-resin composite for evaluation. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0136] [Example 19] Except for the hot water immersion treatment, which involved adding sodium metasilicate (Na2SiO3) to deionized water to adjust the Si ion concentration to 0.93 mg / L and the conductivity to 0.51 mS / m, and immersing the materials in this 95°C hot water for 5 minutes, the hot water immersion treatment was performed in the same manner as in Example 12 to produce metal components (aluminum plates and aluminum discs), and to produce each metal-resin composite for evaluation. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0137] [Example 20] Except for the hot water immersion treatment, which involved adding sodium metasilicate (Na2SiO3) to deionized water to adjust the Si ion concentration to 1.21 mg / L and the conductivity to 0.65 mS / m, and immersing the materials in this 95°C hot water for 5 minutes, the hot water immersion treatment was performed in the same manner as in Example 12 to produce metal components (aluminum plates and aluminum discs), and to produce each metal-resin composite for evaluation. Surface analysis was performed using GD-OES. The measurement results (hydroxyl group abundance) obtained by GD-OES are shown in Table 7. Furthermore, the joint strength and airtightness of the metal-resin joints were evaluated. The evaluation results are shown in Table 7.

[0138] [Table 5]

[0139] [Table 6]

[0140] [Table 7]

[0141] [Table 8]

[0142] [Table 9]

[0143] [Table 10]

[0144] [Consider] Surface analysis using GD-OES revealed that a hydroxyl group-containing film was formed on the surface of the metal component, based on the hydroxyl group abundance. Cross-sectional mapping using EPMA also showed that oxygen elements were localized on the outermost surface of the metal component. These results confirmed that the metal component had a hydroxyl group-containing film on its surface. Furthermore, the results from Examples 1-20 and Comparative Examples 1-8 confirmed that when the hydroxyl group abundance was within a predetermined range, the bonding strength and airtightness were good in the metal-resin joints and metal-resin-metal joints.

[0145] From the results of Examples 1-11, Comparative Examples 1-2, and Comparative Examples 4-6, it can be confirmed that when the surface treatment in the film formation process is laser treatment, regardless of whether the metal substrate is aluminum, copper, or iron, if laser treatment is not performed or if the energy density of the laser treatment is low, the hydroxyl group abundance falls below the lower limit, resulting in insufficient bonding strength and airtightness.

[0146] Furthermore, the results from Examples 12-20 and Comparative Examples 7-8 showed that a hydroxyl group-containing film satisfying a predetermined hydroxyl group abundance can be formed on the surface of a metal substrate by immersion treatment in hot water under predetermined conditions. However, even when the hot water temperature and immersion time are appropriate, it was confirmed that if the amount of Si (Si ions) in the hot water is high, the hydroxyl group abundance decreases, resulting in insufficient bonding strength and airtightness. It is presumed that when there is a high amount of Si (Si ions) in the hot water, the formation of hydroxyl groups in the hydroxyl group-containing film is inhibited by some mechanism.

[0147] SEM cross-sectional observation of the metal-resin joints in Examples 1 and 2 confirmed that when the surface treatment was laser treatment, macro-recessed areas with a micrometer-order size were formed across the entire joint surface. It was also confirmed that the resin penetrated into the macro-recessed areas and bonded together. Furthermore, SEM cross-sectional observation of the metal members confirmed that nanometer-order size fine-recessed areas were formed on the surface of the macro-recessed areas.

[0148] Surface observation by SEM of the metal members before joining in Examples 1 and 2 confirmed that macroscopic and microscopic irregularities were formed on the surface of the metal members. Furthermore, surface observation by SEM of the test resin molded bodies after alkali treatment in Examples 1 and 2 confirmed that the surface of the resin molded body remaining after the metal members were dissolved and removed had a nanometer-order size irregularity shape that replicated the microscopic irregularities. From these results, it was confirmed that in the metal-resin joint, the resin penetrates into the microscopic irregularities and forms a bond.

[0149] Surface observation by SEM before and after chromic acid phosphate treatment in Examples 1 and 2 confirmed that while macro-irregularities remained, fine-irregularities were removed by chromic acid phosphate treatment. Furthermore, after chromic acid phosphate treatment in Examples 1 and 2, the shear strength was slightly lower than before treatment. Also, after chromic acid phosphate treatment in Examples 1 and 2, the airtightness evaluation failed. Furthermore, after stearic acid treatment in Examples 1 and 2, the shear strength was slightly lower than before treatment. Also, after stearic acid treatment in Examples 1 and 2, the airtightness evaluation failed. From these results, it is considered that a certain level of shear strength was maintained regardless of the presence or absence of fine-irregularities, suggesting that mechanical bonding (anchor effect) due to macro-irregularities contributes to the improvement of bonding strength. Furthermore, regardless of the presence or absence of fine irregularities, the absence of hydroxyl groups resulted in a failure of airtightness. This suggests that the chemical bonding through hydrogen bonding between the hydroxyl groups in the hydroxyl group-containing coating on the surface of the metal component and the functional groups contained in the resin contributes particularly to the development of airtightness. [Explanation of Symbols]

[0150] 1…Scanning direction, 2…Beam diameter, 3…Irradiation interval, 4(4')…Laser beam trajectory, 5…Resin molded body, 6(6')…Metal component, 7…Metal-resin joint, 8…Special fixture for shear testing, 9…Metal-resin-metal joint, 10…Water, 11…O-ring, 12…Air blowing tube, 13…Special airtight fixture, 14…Highest convex part Pt1, 15…Lowest concave part Pb1, 16…Fine uneven surface (hydroxyl group-containing film)

Claims

1. A method for manufacturing a metal member comprising a film forming step of forming a hydroxyl group-containing film on the surface of a metal substrate by surface treatment, wherein the hydroxyl group-containing film is formed on the surface of the metal substrate, The aforementioned metal is aluminum or an alloy containing aluminum. The surface treatment is a hot water immersion treatment in which the metal substrate is immersed in hot water at 50°C or higher for 60 seconds or more, and the amount of silicon in the hot water immersion treatment is 0.54 mg / L or more and 2 mg / L or less. A method for manufacturing a metal member, characterized in that, in the film formation step, the surface treatment forms a hydroxyl group-containing film such that, when analyzed from the surface in the depth direction by glow discharge emission spectrometry, the ratio of the amount of detected hydroxyl groups to the total amount of detected metal and hydroxyl groups in the metal substrate is 4% or more and 70% or less.

2. The method for manufacturing a metal member according to claim 1, characterized in that, in the hot water immersion treatment, the conductivity of the hot water is 0.01 mS / m or more and 10 mS / m or less.

3. The present invention provides a resin molding step in which a metal member is obtained by the manufacturing method described in claim 1 or 2, and then a resin molded body is bonded to the surface of the obtained metal member. A method for manufacturing a metal-resin joint comprising at least one metal member and at least one resin molded body, A method for manufacturing a metal-resin joint, characterized in that these metal members and the resin molded body are joined via the hydroxyl group-containing film.

4. The method for manufacturing a metal-resin bond according to claim 3, characterized in that the resin molded body includes a thermoplastic resin or a thermosetting resin.

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