Metallic member, metal-resin bonded body, and methods for manufacturing the same

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, on the surface thereof, a bonding surface for bonding with a bonding target, the metal member comprising a metal base material made of metal and a hydroxyl group-containing film on the surface thereof. The bonding surface is wholly covered with the hydroxyl group-containing film. The hydroxyl group-containing film has on the surface thereof a macro asperitic part comprising a plurality of asperities which have an opening size (D) of 20-200 μm, a depth (L) of 20-200 μm, and the aspect ratio (L / D) of the depth (L) to the opening size (D) of 0.5-5, and also has, on the surface of the macro asperitic part, fine asperities which include a plurality of openings of 10-50 nm and have a thickness of 10-1,000 nm. Also provided is a metal-resin joined body using the metal member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a metal member having a specific joining surface, a joined body of the metal member and a resin molded body, and a method for manufacturing the same. [Background technology]

[0002] In recent years, in the fields of various automotive sensor parts, home appliance parts, industrial equipment parts, and the like, metal-resin joined bodies have come into widespread use, and their applications are expanding, in which a metal material such as a copper substrate made of copper or a copper alloy, which has extremely high heat dissipation properties and electrical conductivity, or an aluminum substrate made of aluminum or an aluminum alloy, which has high heat dissipation properties and is lighter than other metals, is integrally joined to a resin molded body, which has high insulating properties, is lightweight, and is inexpensive.

[0003] Conventionally, an industrially suitable method for producing a metal-resin bonded body in which a metal material and a resin molded body, which are dissimilar materials, are integrally bonded to each other has been developed, in which the metal material is inserted into an injection molding die, a molten thermoplastic resin is injected toward the surface of the inserted metal material, and the metal material and the resin molded body are bonded together at the same time as the resin molded body is formed by injection molding of the thermoplastic resin.Several methods have been proposed to produce this bonded body at lower cost and with improved bonding strength.

[0004] For example, the present inventors have proposed a technique in which a specific treatment is performed on the surface of a metal substrate to form an oxygen-containing film containing oxygen on the surface of the metal substrate, and then a resin molded article is bonded to the metal substrate via the formed oxygen-containing film (e.g., Patent Documents 1 to 3). These techniques are methods that minimize the risk of corrosion of metal parts or devices or contamination of the surrounding environment, which were problems with previously proposed surface treatment techniques, and they were able to achieve a certain level of bonding strength and airtightness. However, when wet treatments are used to form hydrated oxide films or zinc-containing films to form oxygen-containing films, macro-asperities are not formed, resulting in insufficient bonding strength for resin joints, leaving room for further improvement in the treatment method. In contrast, the methods described in Patent Documents 1 to 3, which use laser light, while advantageous in that they can form macro-asperities, are performed under conditions in which the irradiation interval (pit width) is equal to or smaller than the spot diameter (beam diameter) specific to the laser oscillator. In such cases, the desired macro-asperities are not formed, resulting in reduced bonding strength and difficulty in ensuring airtightness, leaving room for further improvement in this area as well.

[0005] On the other hand, as mentioned above, several techniques have been proposed for forming metal-resin bonded bodies, in which the surface of a metal material is treated with laser light. For example, Patent Document 4 discloses that when a laser beam is applied to the joining surface of a metal molded body to form a large number of holes or grooves, "protrusions" consisting of burrs are formed on both sides of the openings of the holes or grooves, and these "protrusions" are embedded in the resin molded body to enhance the joining strength. Patent Document 5 also discloses a metal-resin composite molded product that can suppress deformation due to laser processing even when the metal plate is thin, using a technology that uses laser beam to form irregularities with a desired undercut ratio on the surface of a metal plate to improve adhesion between the metal plate and the resin. Patent Document 6 also discloses laser processing conditions for forming a joint on the metal surface for joining to the resin, using a process of laser scanning the metal surface in one scanning direction and a process of laser scanning in an intersecting scanning direction. This allows the joint to have an uneven shape, but preferably some of it can be formed as a "bridge shape" where the convex parts are connected to form an arch shape with a hole at the bottom, or the convex parts can be "overhanging" to form a mushroom or cedar tree shape, thereby enhancing the anchoring effect between dissimilar materials at the joint. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6004046 [Patent Document 2] Patent No. 6017675 [Patent Document 3] Patent No. 6387301 [Patent Document 4] Patent No. 5889775 [Patent Document 5] Japanese Patent Publication No. 2020-116806 [Patent Document 6] Patent No. 4020957 Summary of the Invention [Problem to be solved by the invention]

[0007] In Patent Document 4, there are non-laser-irradiated areas sandwiched between the protrusions made up of burrs that make up the protrusion group. The presence of such non-laser-irradiated areas may cause a decrease in bonding strength and may not ensure airtightness. In addition, in Patent Document 5, the depth of the unevenness is shallow, which poses an issue in that the bonding strength is insufficient depending on the product. Furthermore, in Patent Document 6, laser scanning is required in two intersecting directions, which requires too much processing time, leaving room for improvement. Furthermore, the presence of non-laser-irradiated areas (untreated areas) at the bottom of the "bridge shape," which is considered to be a preferred shape, may reduce bonding strength and airtightness.

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

[0009] That is, the gist of the present invention is as follows. [1] A metal member having a joining surface for joining objects on its surface, The metal member includes a metal substrate made of metal and a hydroxyl group-containing coating that contains hydroxyl groups and is formed on the surface of the metal substrate; the hydroxyl group-containing coating is formed over the entire surface of the joining surface, The hydroxyl group-containing coating is a metal component characterized in that it has a macro-irregularity on its surface, which is made up of a plurality of irregularities, each having an opening diameter (D) of 20 μm to 200 μm, a depth (L) of 20 μm to 200 μm, and an aspect ratio (L / D) of the opening diameter (D) to the depth (L) of 0.5 to 5, and also has a micro-irregularity on the surface of the macro-irregularity, which has a plurality of openings of 10 nm to 50 nm and a thickness of 10 nm to 1000 nm. [2] The metal component according to [1], characterized in that when the hydroxyl-containing coating is analyzed by glow discharge optical emission spectrometry from the surface in the depth direction, the ratio of the detected amount of hydroxyl groups to the total amount of the detected amount of the metal in the metal substrate and the detected amount of the hydroxyl groups is 4% or more. [3] The metal member according to [1] or [2], characterized in that the metal is aluminum, copper, iron, or an alloy containing any of these metals. [4] The metal member according to any one of [1] to [3], wherein the fine concave-convex portion is a spongy structure having the openings. [5] The metal member according to any one of [1] to [4], wherein the metal is aluminum or an alloy containing aluminum. [ 6 ][1]~[ 5 and at least one resin molded body on a surface of the metal member, wherein the metal member and the resin molded body are bonded together via the bonding surface in a state where the resin has penetrated into the macro-concave and micro-concave portions. [ 7 The resin molded body is characterized in that it contains a thermoplastic resin or a thermosetting resin. 6 ] The metal-resin bonded body according to the present invention. [ 8 ] A method for manufacturing a metal member having a surface to be joined with an object to be joined, a film-forming step of forming a hydroxyl group-containing film on the surface of a metal substrate by laser treatment in which a laser beam is irradiated onto the surface of the metal substrate; In the film forming step, the joining surface is formed with the hydroxyl group-containing film formed over the entire surface by the laser treatment, In the film formation step, the laser treatment forms the hydroxyl-containing film on its surface, which has a macroscopic unevenness consisting of a plurality of unevennesses, each having an opening diameter (D) of 20 μm to 200 μm, a depth (L) of 20 μm to 200 μm, and an aspect ratio (L / D) of the opening diameter (D) to the depth (L) of 0.5 to 5, and the entire surface of the macroscopic unevenness has a plurality of openings of 10 nm to 50 nm, and the hydroxyl-containing film has a microscopic unevenness on its surface, having a thickness of 10 nm to 1000 nm. [ 9In the film forming process, the energy density in the laser treatment is 0.5 J / mm 2 The above is characterized by the above. 8 ] A method for producing a metal member according to the present invention. [ 10 In the film forming step, the laser treatment forms the hydroxyl group-containing film, in which, when analyzed from the surface in the depth direction by glow discharge optical emission spectrometry, the ratio of the detected amount of hydroxyl groups to the total amount of the detected amount of the metal and the detected amount of the hydroxyl groups in the metal substrate is 4% or more. 8 ]or[ 9 ] A method for producing a metal member according to the present invention.

[11] The method for manufacturing a metal member according to any one of [8] to

[10] , wherein the fine concave-convex portion is a spongy structure having the openings.

[12] The metal is aluminum, copper, iron, or an alloy containing any of these metals; In the film forming process, the energy density (J / mm 2 ) is expressed by the following formula (A1) using the laser light output W (W), the number of laser light scans N (times), the laser light irradiation interval C (mm), the laser light scanning speed V (mm / s), the length of the laser irradiated area perpendicular to the irradiation direction of the laser light Length, and the width of the laser irradiated area parallel to the irradiation direction of the laser light Width: Energy density = (((Length / C) × Width × N) / V) × W) / (Length × Width) Equation (A1) In the film forming process, the energy density (J / mm 2 ) is calculated by formula (A2) obtained by transforming formula (A1), Energy density = (W × N) / (C × V) Equation (A2) In the film forming step, when laser treatment is performed on the metal substrate containing aluminum as the main metal, the energy density in the laser treatment is 0.5 J / mm 2 More than 4J / mm 2 When performing laser treatment on the metal substrate containing iron as the main metal, the energy density in the laser treatment is 1 J / mm or less. 2 More than 10J / mm 2 When laser treatment is performed on the metal substrate containing copper as the main metal, the energy density in the laser treatment is 2 J / mm or less. 2 More than 20J / mm 2 The method for producing a metal member according to any one of [8] to

[11] , characterized in that:

[13] The method for producing a metal member according to any one of [8] to

[12] , wherein the metal is aluminum or an alloy containing aluminum. [ 14 ][ 8 ]~[ 13 a resin molding step of bonding a resin molded body to a surface of the obtained metal member after obtaining the metal member by the method according to any one of the above. A method for producing a metal-resin joined body including at least one metal member and at least one resin molded body, A method for producing a metal-resin bonded body, characterized in that the metal member and the resin molded body are bonded via the bonding surface in a state in which the resin has penetrated into the macro-convex and micro-concave portions. [ 15 ] In the joining of the resin joined body in the resin molding step, a resin composition containing a thermoplastic resin or a thermosetting resin is used for molding on the metal member. 14 ] A method for producing a metal-resin bonded body according to the above. [Effects of the Invention]

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

[0011] [Figure 1] FIG. 1 is a diagram (photograph) showing how to determine the opening diameter (D) and depth (L) in the macro concave-convex portion. [Figure 2] FIG. 2 is a schematic diagram showing the relationship between the beam diameter of the laser light and the irradiation interval. [Figure 3] FIG. 3 is a diagram for explaining an outline of the bonding strength evaluation (1) (shear test). [Figure 4] FIG. 4 is a diagram for explaining an outline of the bonding strength evaluation (2) (shear test). [Figure 5] FIG. 5 is a diagram for explaining an outline of the evaluation of the airtightness of a metal-resin bonded body. [Figure 6] FIG. 6 is a diagram for explaining an outline of the evaluation of the airtightness of a metal-resin-metal bonded body. [Figure 7] FIG. 7 is a diagram showing an outline of a metal-resin bonded body for evaluation of bonding strength. [Figure 8] FIG. 8 is a diagram showing an outline of the metal-resin bonded body for the evaluation of airtightness. [Figure 9] FIG. 9 is a diagram (photograph) of the joint cross section of the metal-resin joined body produced in Example 1, observed with an SEM. [Figure 10]FIG. 10 is a diagram (photograph) for precise cross-sectional evaluation when the joint cross section of the metal-resin joined body produced in Example 1 is observed with an SEM. [Figure 11] FIG. 11 is a diagram (photograph) of the surface of the metal member produced in Example 1 before resin bonding, observed with an SEM. [Figure 12] FIG. 12 is a diagram (photograph) of the surface of the resin molded body observed with an SEM after the metal-resin bonded body produced in Example 1 was subjected to an alkali treatment. [Figure 13] FIG. 13 is a diagram (photograph) of the surface of the metal member produced in Example 1 before resin bonding, observed with an SEM after the metal member was subjected to a phosphoric chromate treatment. [Figure 14] FIG. 14 is a diagram (graph) showing the results of a surface analysis by GD-OES of the metal member produced in Example 1 before resin bonding. [Figure 15] FIG. 15 is a diagram showing the results of cross-sectional mapping, performed by EPMA, of the metal member produced in Example 1 before resin bonding. [Figure 16] FIG. 16 is a diagram (photograph) of the joint cross section of the metal-resin joined body produced in Example 2, observed with an SEM. [Figure 17] FIG. 17 is a diagram (photograph) of the surface of the metal member produced in Example 2 before resin bonding, observed with an SEM. [Figure 18] FIG. 18 is a diagram (photograph) of the surface of the resin molded body observed with an SEM after the metal-resin bonded body produced in Example 2 was subjected to an alkali treatment. [Figure 19] FIG. 19 is a diagram (photograph) of the surface of the metal member produced in Example 2, observed with an SEM after the metal member was subjected to a phosphoric chromate treatment before resin bonding. [Figure 20] FIG. 20 is a diagram (photograph) of the joint cross section of the metal-resin joined body produced in Example 3, observed with an SEM. [Figure 21] FIG. 21 is a diagram (photograph) of a cross section of the resin bonding surface side of the metal member produced in Example 4 before resin bonding, observed with an SEM. [Figure 22]FIG. 22 is a diagram showing an outline of a metal-resin-metal bonded body for evaluation of bonding strength according to Example 5. As shown in FIG. [Figure 23] FIG. 23 is a diagram showing an outline of a metal-resin-metal bonded body for evaluating airtightness according to Example 5. As shown in FIG. [Figure 24] FIG. 24 is a diagram (photograph) of the joint cross section of the metal-resin-metal joint body produced in Example 5, observed with an SEM. [Figure 25] FIG. 25 is a diagram (photograph) of a cross section of the resin bonding surface side of the metal member produced in Example 6 before resin bonding, observed with an SEM. [Figure 26] FIG. 26 is a diagram (photograph) of a cross section of the resin bonding surface side of the metal member produced in Example 7 before resin bonding, observed with an SEM. [Figure 27] FIG. 27 is a diagram (photograph) of a joint cross section of the metal-resin joined body produced in Comparative Example 1, observed with an SEM. [Figure 28] FIG. 28 is a diagram (photograph) of a cross section of the resin bonding surface side of the metal member produced in Comparative Example 2 before resin bonding, observed with an SEM. [Figure 29] FIG. 29 is a diagram (photograph) of a cross section of the resin bonding surface side of the metal member produced in Comparative Example 3 before resin bonding, observed with an SEM. [Figure 30] FIG. 30 is a diagram (photograph) of a cross section of the metal-resin bonded body produced in Comparative Example 4, observed with an SEM. [Figure 31] FIG. 31 is a diagram (photograph) of a cross section of the resin bonding surface side of the metal member produced in Comparative Example 5 before resin bonding, observed with an SEM. [Figure 32] FIG. 32 is a diagram (photograph) of a cross section of the resin bonding surface side of the metal member produced in Comparative Example 6 before resin bonding, observed with an SEM. DETAILED DESCRIPTION OF THE INVENTION

[0012] The metal member and metal-resin bonded body of the present invention will be described in detail below, along with their manufacturing methods. The components of the present invention described below can be combined in part or in whole as appropriate.

[0013] [1. Metallic components and metal-resin joints] The metal member of the present invention is a metal member having a surface to be bonded to an object to be bonded, and includes a metal substrate made of metal and a hydroxyl-containing coating containing hydroxyl groups formed on the surface of the metal substrate. The hydroxyl-containing coating has a macro-relief on its surface and a micro-relief on the surface of the macro-relief. The metal-resin bonded body of the present invention includes a metal member and a resin molded body on the surface of the metal member.

[0014] [1-1. Metallic Components] <Metal base material> First, the metal substrate used in the metal member of the present invention may be a copper substrate made of copper or a copper alloy, an iron substrate made of iron or an iron alloy, or an aluminum substrate made of aluminum or an aluminum alloy. The material is not limited, and can be selected based on the application of the metal-resin bonded body formed therefrom and various physical properties required for that application, such as strength, corrosion resistance, and processability. Examples of suitable materials include processed materials obtained by appropriately processing them into a desired shape, and combined materials obtained by appropriately combining these processed materials. Depending on the application, a substrate with a thickness of approximately 0.3 mm to 10 mm is typically used. Typically, an oxide film is formed on the surface of the metal substrate. The oxide film may be a natural oxide film formed naturally 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 with the metal substrate is not particularly limited as long as it is a material that can be joined with the metal substrate. It is preferable to use 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. The resin molded body will be described later.

[0016] <Joint surface> The bonding surface formed on the metal substrate may be only a portion of one side of the metal substrate, the entire surface, or a portion or entire surface of both sides, as long as the bonding surface is formed in the necessary portion depending on the intended use. Furthermore, there are no particular limitations on the shape, size, arrangement, etc. of the bonding surface. The same applies to combined materials, etc. In the present invention, the "bonding surface" refers to the area where the metal substrate and resin are to be bonded, and refers to the area on the surface of the metal substrate where a predetermined treatment has been applied for bonding with the resin. In contrast, the area where the metal substrate and resin are bonded is referred to as the "bonding portion" to distinguish it from the above.

[0017] <Hydroxyl group-containing film> A hydroxyl-containing coating is formed over the entire joining surface. As shown in the drawing, the hydroxyl-containing coating has a macroscopically roughened portion formed by alternating convex and concave portions, and a micro-roughened portion formed on the surface of the macro-roughened portion.

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

[0019] The hydroxyl group abundance is preferably 4% or more, more preferably 5% or more, even more preferably 6% or more, and particularly preferably 7% or more. When the hydroxyl group abundance is equal to or greater than the above-mentioned lower limit, the number of hydroxyl groups present near the surface of the metal member 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 bonded body. Furthermore, the bonding strength of the metal-resin bonded body also tends to improve. The upper limit of the hydroxyl group abundance is not particularly limited, but is preferably 70% or less, more preferably 50% or less, even more preferably 40% or less, and particularly preferably 30% or less. The hydroxyl group abundance varies depending on the method of hydroxyl group formation. For example, compared to when a metal substrate is subjected to laser treatment, when the metal substrate is subjected to a wet treatment such as a hydrated oxide treatment using warm or hot water, a chemical conversion treatment, or a zincate treatment, the hydroxyl group abundance tends to be higher. When a hydroxyl group-containing coating is formed by laser treatment, the hydroxyl group abundance is preferably 30% or less, more preferably 20% or less, even more preferably 15% or less, and particularly preferably 10% or less.

[0020] The hydroxyl group-containing coating contains, depending on the metal constituting the metal substrate, a hydroxide (metal hydroxide) or an oxide hydroxide (metal oxide hydroxide) of the metal constituting the metal substrate, such as aluminum hydroxide (Al(OH)), aluminum oxide hydroxide (AlO(OH)), copper hydroxide (Cu(OH)), iron(II) hydroxide (Fe(OH)), or iron(III) oxide hydroxide (FeO(OH)). The hydroxyl group-containing coating may also contain, depending on the metal constituting the metal substrate, an oxide (metal oxide) of the metal constituting the metal substrate, such as aluminum oxide (AlO), copper(I) oxide (CuO), copper(II) oxide (CuO), iron(II) oxide (FeO), iron(II,III) oxide (FeO), or iron(III) oxide (FeO).

[0021] On the surface of the metal substrate, a deposit is formed in the form of a film, in which metal oxides formed due to laser irradiation accumulate around the irradiated area. The metal fusing layer made of such deposits contains oxygen as the metal oxide as described above. The metal fusing layer has a hydroxyl-containing film having hydroxyl groups in the outermost layer. In the present invention, as described above, the entire joining surface is covered with a hydroxyl-containing film having macro-irregularities and micro-irregularities.

[0022] In this specification, "the entire surface to be bonded" does not necessarily mean 100% of the surface area of ​​the surface to be bonded, and does not exclude the case where there are very small spots of the surface that are not covered with the hydroxyl-containing film due to unirradiated areas. Preferably, 90% or more, more preferably 95% or more of the surface to be bonded is covered with the hydroxyl-containing film.

[0023] <Macro unevenness> The macro-relief is a structure having a micrometer-order irregular shape and is formed on the surface of the hydroxyl group-containing coating. The macro-relief has a structure consisting of recesses formed by perforating the metal substrate upon irradiation with laser light and protrusions consisting of metal oxide deposits formed by irradiation with laser light. Multiple laser light irradiations are performed adjacent to each other, resulting in a repeating structure consisting of recesses and protrusions. The macro-relief can be confirmed by observing the surface or cross section of the metal member using, for example, a scanning electron microscope (SEM).

[0024] It is important that the macro-relief portion has a predetermined opening diameter (D) and depth (L) determined by the procedure described with reference to FIG. 1. It is also important that the macro-relief portion has a predetermined aspect ratio (L / D). The macro-relief portion contains a metal hydroxide or a metal oxide hydroxide, similar to the hydroxyl-containing film. The macro-relief portion may also contain a metal oxide, similar to the hydroxyl-containing film.

[0025] To calculate the opening diameter (D) and depth (L), a cross section of the metal member or metal-resin bonded body is observed using an SEM, and a cross-sectional image is taken of the multiple concave-convex portions formed by laser irradiation, in which at least 12 concave portions and 11 convex portions are alternately arranged in succession. The opening diameter (D) and depth (L) can then be calculated from the multiple concave-convex portions included in the cross-sectional image.

[0026] Specifically, as shown in FIG. 1 , the depth is determined by drawing the following lines on the cross-sectional photograph. First, for 12 arbitrarily selected consecutive recesses in the cross-sectional photograph, the deepest of the bottoms of each recess is designated as the minimum recess Pb1 (reference symbol: 2). A reference line RL1 is drawn that passes through the minimum recess Pb1 or a position lower than Pb1 and passes through the position where the sum of the distances from the respective bottoms of each recess is smallest. Next, in the cross-sectional photograph, the highest convex portion among the convex portions sandwiched between the 12 recesses is designated as the apex convex portion Pt1 (reference symbol: 1). A reference line RL2 is drawn that passes through the apex convex portion Pt1 and is parallel to the reference line RL1. In this way, by drawing RL1 and RL2 so that they pass through the minimum recess Pb1 and the apex convex portion Pt1, respectively, it is possible to prevent the depth L from being calculated as being excessively larger or smaller than the actual value, resulting in an aspect ratio being calculated as being too large or small. Next, in the cross-sectional photograph described above, for 12 consecutive recesses including the bottommost recess Pb1, 12 straight lines are drawn from the bottom of each recess in a direction perpendicular to the reference line RL2, and these straight lines are designated as lines a to l (shown as dashed lines in Figure 1, etc.).

[0027] Parallel median lines are drawn midway between adjacent lines a through l described above, and these median lines are designated as lines A through K, respectively. The distance between lines A and B is taken as the opening diameter D1 of the recess between lines A and B and through which line b passes. Similarly, the distances between adjacent lines A through K are taken as opening diameters D1 through D10. Furthermore, for each of lines b through k, the distance from the bottom of each recess to reference line RL2 is taken as the depths L1 through L10 of the ten recesses. The opening diameters D1 through D10 and depths L1 through L10 correspond to the opening diameters D and depths L, respectively, of the ten recesses through which lines b through k pass, excluding the lines a and l at both ends.

[0028] In this way, the depths L1 to L10 and opening diameters D1 to D10 can be obtained for the 10 recesses through which lines b to k in the cross-sectional image pass. Furthermore, the Smirnoff-Grubbs test is used to detect outliers among the depths L1 to L10 and opening diameters D1 to D10. To detect outliers, the absolute deviation is calculated by subtracting the value of each depth L for the 10 recesses with depths L1 to L10 from the average value of the depths L1 to L10. The calculated absolute deviation is then divided by the unbiased standard deviation of the depths L1 to L10 to calculate the test statistic t. Next, a p-value is calculated, which represents the probability that the test statistic t will be that value. Any p-value less than 5% is detected as an outlier. If an outlier is detected, the depth L of the recess where the outlier was detected is excluded from the 10 recesses with depths L1 to L10, and outlier detection is performed again for the remaining depths L of the recesses. This process is repeated until no outliers are detected. Similarly, outliers are detected for the opening diameters D1 to D10. Furthermore, for the 10 recesses through which lines b to k included in the cross-sectional photograph 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 recesses for which outliers were detected in either or both of the depth L and opening diameter D. The average depth L and average opening diameter D thus obtained are defined as the depth (L) and opening diameter (D) of the metal member or metal-resin bonded body.

[0029] Furthermore, for the ten recesses through which lines b to k included in the cross-sectional photograph described above pass, recesses for which outliers were detected in either or both of the depth L and the opening diameter D were excluded, and the depth L of each recess was divided by the opening diameter D of each recess to calculate the aspect ratio (L / D) of each recess.The average aspect ratio (L / D) of the multiple recesses was then calculated from the aspect ratio (L / D) of each recess.The average aspect ratio (L / D) thus obtained was designated as the aspect ratio (L / D) of the metal member or the metal-resin bonded body.

[0030] In the present invention, the opening diameter (D) is usually 20 μm to 200 μm, preferably 40 μm to 180 μm, more preferably 60 μm to 150 μm, and even more preferably 80 μm to 120 μm. When the opening diameter (D) is equal to or greater than the lower limit, the recess is widened, making it easier for the resin to be bonded to enter the recess and also making it easier to satisfy the aspect ratio described below. On the other hand, when the opening diameter (D) is equal to or less than the upper limit, the interlocking effect due to the intrusion of the resin is more easily exhibited and also making it easier to satisfy the aspect ratio described below.

[0031] In the present invention, the depth (L) is 20 μm to 200 μm, preferably 40 μm to 180 μm, more preferably 60 μm to 150 μm, and even more preferably 80 μm to 120 μm. When the depth (L) is equal to or greater than the lower limit, the depth is sufficient, making it easier for the interlocking effect due to the infiltration of the resin to be exhibited, and also making it easier to satisfy the aspect ratio described below. On the other hand, when the depth (L) is equal to or less than the upper limit, it is possible to prevent the formation of a coarse uneven structure due to both the depth (L) value and the opening diameter (D) becoming large, making it easier for the interlocking effect due to the infiltration of the resin to be exhibited, and also making it easier to satisfy the aspect ratio described below.

[0032] In the present invention, the aspect ratio (L / D) of the opening diameter (D) to the depth (L) is typically 0.5 to 5, preferably 0.5 to 4, more preferably 0.7 to 3, and even more preferably 1 to 2. By satisfying this aspect ratio, the resin flows deep into the recesses, suppressing the generation of voids between the macro-irregularities and the resin, sealing the entire surface of the hydroxyl-containing coating, and increasing the surface area of ​​the hydroxyl-containing coating that interacts with the resin. Thus, by forming recesses in a shape that fully exhibits the interaction between the metal member and the resin, the bonding strength and airtightness between the metal member and the resin molded article can be improved. By forming recesses with an L / D ratio greater than the above-mentioned lower limit, the depth of the recesses is not too small relative to the opening diameter, resulting in a recess with an appropriate depth, which is more likely to exhibit the interaction between the metal member and the resin when the resin flows into the recesses. Furthermore, by making the aspect ratio lower than the upper limit value, the depth of the recess is not too large relative to the opening diameter, and the width of the recess gradually narrows from the opening toward the depth, forming an approximately triangular shape, making it easier for resin to flow deep into the recess.

[0033] <Minute unevenness> The fine irregularities are structures having irregular shapes on the order of nm, and are formed on the macro irregularities on the surface of the hydroxyl-containing coating. The fine irregularities are formed on the surface of the hydroxyl-containing coating when a metal melt layer having the hydroxyl-containing coating is formed by laser irradiation. The fine irregularities can be confirmed by observing the surface or cross section of the metal member using, for example, a scanning electron microscope.

[0034] The fine irregularities have nano-sized fine openings of 10 nm to 50 nm formed therein, and have a fine structure with a film thickness of 10 nm to 1000 nm. When observed with an SEM, the fine irregularities are observed as a spongy structure with fine openings of the above size. The fine irregularities contain a metal hydroxide or a metal oxide hydroxide, similar to the hydroxyl group-containing film. The fine irregularities may also contain a metal oxide, similar to the hydroxyl group-containing film.

[0035] The inventors' investigations have confirmed that the penetration of the resin into the macro-convex and micro-concave portions, or the chemical bonding between the hydroxyl groups of the hydroxyl-containing coating and the functional groups in the resin, contribute to ensuring bonding strength and airtightness. While there are still some unclear points regarding this, as confirmed in the Examples (Examples 1 and 2) described below, the effectiveness of the hydroxyl-containing coating (micro-concave portions) can be confirmed by performing i) a chromic acid phosphate treatment or ii) a stearic acid treatment on a metal component on which a hydroxyl-containing coating has been formed. The mechanism is as follows: i) A chromic acid phosphate solution dissolves the aluminum substrate more slowly than the aluminum oxide. Treating a metal component with a chromic acid phosphate solution selectively dissolves the aluminum oxide in the outermost layer, leaving the aluminum substrate as the outermost layer after treatment. During this process, the micro-convex and micro-concave structure of the hydroxyl-containing coating disappears, and the hydroxyl groups in the surface layer also disappear. In addition, ii) stearic acid has a hydrophilic carboxyl group (-COOH) and a hydrophobic alkyl group (-C 17 H 35 ) and has the property of forming a monomolecular film with a thickness of one molecule. When a metal component is treated with stearic acid, the hydroxyl groups present on the surface of the hydroxyl-containing film interact (hydrogen bond) with the COOH groups of the stearic acid, and the surface of the hydroxyl-containing film is covered with the hydrophobic groups of the stearic acid. This maintains the shape of the fine irregularities, but eliminates the activity of the hydroxyl groups present on the surface of the fine irregularities.

[0036] [1-2. Resin molding] Next, we will explain a resin molded body that is suitable for use as a joining object for a metal member having a predetermined joining surface. The resin molded body can be formed by molding a resin composition onto the surface of the metal member. The resin molded body contains a thermoplastic resin or a thermosetting resin.

[0037] The thermoplastic resin can be selected from known resins depending on the application, and examples thereof include polyamide resins (aliphatic polyamides such as PA6 and PA66, and 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, and these can be used alone or in combination of two or more. Among these, polyamide resins and polyphenylene sulfide resins are preferred because they have high fluidity during resin molding and easily penetrate into recesses.

[0038] The thermosetting resin can be appropriately selected from known resins depending on the application, and examples thereof include urea resins, melamine resins, phenolic resins, resorcinol resins, epoxy resins, polyurethanes, and vinyl urethanes, and these can be used alone or in combination of two or more. Among these, it is preferable to use epoxy resins, acrylic resins, and urethane resins, because reaction-curing adhesives are compatible with hydroxyl group-containing films and can provide high bonding strength as the reaction area increases.

[0039] Furthermore, adhesives can also be used as the resin molded body. Examples of adhesives include the above-mentioned thermoplastic resins or thermosetting resins, or other elastomers or rubbers, and compounds exhibiting adhesive properties. The adhesive can be selected from known adhesives depending on the application. For example, dry-hardening adhesives include acrylic resin emulsions, rubber latexes, vinyl acetate resin solvents, vinyl copolymer resin solvents, and rubber solvents. Reaction-curing adhesives include epoxy resins, urethane resins, and modified silicone resins, and these can be used alone or in combination. Among these, epoxy resins, acrylic resins, and urethane resins are preferred because reaction-curing adhesives are compatible with hydroxyl-containing coatings and can achieve high bonding strength as the reaction area increases.

[0040] Furthermore, thermoplastic elastomers can be used, such as styrene-based elastomers, vinyl chloride-based elastomers, olefin-based elastomers, urethane-based elastomers, polyester-based elastomers, nitrile-based elastomers, and polyamide-based elastomers, and these can be used alone or in combination of two or more.

[0041] Furthermore, in each of the above resins (resin compositions), in order to further improve performance such as adhesion to metal members, mechanical strength, heat resistance, dimensional stability (resistance to deformation, warpage, etc.), and electrical properties, fibrous, granular, plate-like fillers, and various elastomer components can be added.

[0042] Furthermore, known additives that may generally be added to the resin (resin composition), namely, flame retardants, colorants such as dyes and pigments, stabilizers such as antioxidants and ultraviolet absorbers, plasticizers, lubricants, slip agents, mold release agents, crystallization accelerators, crystal nucleating agents, etc., may be added appropriately to the resin (resin composition) within a range that does not impair the required performance or the object of the present invention.

[0043] [1-3. Metal-resin bonded body] A metal-resin bonded body is formed with the resin embedded in the bonding surface (macro-concave and micro-concave portions) of the surface of the metal member, and the metal member and the resin molded body are integrally bonded via the bonding surface. The metal member and the resin molded body may be bonded using one metal member and one resin molded body, or a plurality of either or both may be bonded, or a plurality of sets of these may be laminated in any order, and this can be determined appropriately depending on the application.

[0044] For example, the metal-resin bonded body may be a metal-resin bonded body in which a metal member and a resin molded body are bonded together in a stacked or continuous arrangement. Alternatively, the metal-resin bonded body may be a metal-resin-metal bonded body in which a metal member, a resin molded body, and a metal member are bonded together in a stacked or continuous arrangement in this order. Alternatively, the metal-resin bonded body may be a resin-metal-resin bonded body in which a resin molded body, a metal member, and a resin molded body are bonded together in a stacked or continuous arrangement in this order.

[0045] When the metal resin bonded body is a metal-resin-metal bonded body in which two or more metal members are bonded via a resin molded body, the bonded body may include a resin molded body formed by molding a thermoplastic resin or a thermosetting resin and sandwiched between metal members. Alternatively, the bonded body may be a resin molded body in which an adhesive containing a thermoplastic resin or a thermosetting resin is used as the resin molded body and the metal members are bonded via the adhesive.

[0046] [2. Methods for producing metal members and metal-resin bonded bodies] The method for producing a metal member of the present invention is a method for producing a metal member having a surface to be bonded to an object to be bonded, and includes a film formation step of forming a hydroxyl-containing film containing hydroxyl groups on the surface of a metal substrate made of metal.The method for producing a metal-resin bonded body of the present invention includes a resin molding step of bonding a resin molded body to the surface of the metal member.

[0047] [2-1.Metal component manufacturing method] <Preparation process> The method for producing a metal member of the present invention may include a preparation step of performing pretreatment such as degreasing, etching, desmutting, chemical polishing, and electrolytic polishing as a pretreatment of the surface of the metal substrate prior to the coating formation step.

[0048] <Film formation process> In the present invention, in the coating formation step, the surface of the metal substrate prepared as described above is irradiated with laser light (hereinafter simply referred to as "laser treatment"). The laser treatment forms a bonding surface with the object to be bonded, thereby obtaining the metal component of the present invention. The laser treatment also forms a hydroxyl group-containing coating on the surface of the metal substrate. Here, although known lasers can be used as the laser, it is preferable to use a pulsed laser, such as a YAG laser, a YVO4 laser, a semiconductor laser, or a fiber laser, as this is advantageous for processing the metal substrate in a spot manner as in the present invention.

[0049] The principle of forming a hydroxyl group-containing film is roughly as follows. That is, the metal substrate is melted and evaporated by the energy of the laser irradiation, and the spaces created by the evaporation become the bases of recesses, and the areas on both sides (neighboring sides) of the recesses that are not irradiated by the laser become the bases of protrusions. At the same time, the molten metal parts are oxidized in part or in whole to become metal oxides, which are deposited around the irradiated areas that become recesses, forming protrusions. The deposits made of metal oxides are formed in the form of a film, covering the recesses and protrusions. In this way, the deposits made of metal oxides formed on the surface of the metal substrate form a molten metal layer that forms the uneven shape of the macro-unevenness. Furthermore, metal oxides have at least some partial ionicity, and metal ions (Al) are present on the surface of the metal oxide. 3+ ) and oxide ions (O 2- ) are present. Due to their electrostatic neutrality, they react with moisture in the air to hydroxylate the metal oxides present on the surface of the metal fusing layer, and the surface of the metal fusing layer becomes covered with hydroxyl groups. In this way, a hydroxyl-containing film containing hydroxyl groups is formed on the outermost layer of the metal fusing layer.

[0050] In addition, when there is a laser-unirradiated portion of the metal member that has not been irradiated with a laser, there is no metal melt layer and no hydroxyl-containing coating in the laser-unirradiated portion. Usually, an oxide coating is formed in the laser-unirradiated portion. Since the laser-unirradiated portion does not have a hydroxyl-containing coating, there is no improvement in airtightness due to chemical bonding caused by hydroxyl groups. Furthermore, when the laser-unirradiated portion is flat, there is no improvement in bonding strength due to mechanical bonding caused by macro-irregularities. Therefore, when there is a laser-unirradiated portion remaining on the bonding surface and a hydroxyl-containing coating is not formed on the entire bonding surface, the airtightness and bonding strength of the metal-resin bonded body are reduced.

[0051] <Laser treatment conditions> In order to provide the hydroxyl group-containing coating having the macro-concave and micro-concave portions as described above, it is preferable to set the laser treatment conditions taking the following points into consideration.

[0052] Laser processing is affected by the laser beam irradiation energy 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 portion of the object (workpiece) to be laser processed. Energy density (J / mm 2 ) is expressed by the following formula (A1) using the laser light output W (W), the number of laser light scans N (times), the laser light irradiation interval C (mm), the laser light scanning speed V (mm / s), the length of the laser irradiated area perpendicular to the irradiation direction of the laser light Length, and the width of the laser irradiated area parallel to the irradiation direction of the laser light Width. Energy density = (((Length / C) × Width × N) / V) × W) / (Length × Width) Equation (A1) By modifying formula (A1), the following formula (A2) is obtained: Energy density can be calculated using formula (A2). Energy density = (W × N) / (C × V) Equation (A2)

[0053] The energy density is preferably 0.5 J / mm 2 That's all. As the energy density increases, fine irregularities having hydroxyl groups are more likely to form on the surface of a metal component subjected to laser treatment. Also, a hydroxyl-containing coating having a predetermined hydroxyl group abundance ratio is more likely to be formed. Furthermore, as the energy density increases, the depressions in the macro irregularities formed on the surface of the metal substrate tend to become deeper, resulting in increased surface roughness for the metal component after laser treatment. The higher the melting point and the greater the thermal diffusion of the metal constituting the metal substrate, the less susceptible the metal substrate tends to be to the effects of laser light. Taking the above-mentioned circumstances into consideration, it is desirable to change the energy density according to the metal to be treated with the laser.

[0054] When performing laser processing on a metal substrate containing aluminum as the main metal, the energy density is preferably 0.5 J / mm 2 More than 1 J / mm 2 More preferably, 1.5 J / mm 2 In addition, when performing laser processing on a metal substrate containing aluminum as the main metal, the energy density is preferably 5 J / mm 2 Less than 4J / mm 2 Less than 3 J / mm 2 The following is the result.

[0055] When performing laser processing on a metal substrate mainly made of iron, the energy density is preferably 1 J / mm 2 More than 2J / mm 2 More preferably, 3 J / mm 2 In addition, when performing laser processing on a metal substrate containing iron as the main metal, the energy density is preferably 10 J / mm 2 Less than or equal to 8 J / mm 2 Less than 6 J / mm 2 The following is the result.

[0056] When laser processing is performed on a metal substrate containing copper as the main metal, the energy density is preferably 2 J / mm 2 More than 4J / mm 2 More preferably, 6 J / mm 2 In addition, when performing laser processing on a metal substrate containing copper as the main metal, the energy density is preferably 20 J / mm 2 Less than or equal to 15 J / mm 2 Less than 10 J / mm 2 The following is the result.

[0057] When the energy density is equal to or greater than the lower limit, fine irregularities having hydroxyl groups are easily formed on the surface of the laser-treated metal member. Furthermore, a hydroxyl-containing coating having a predetermined hydroxyl group abundance ratio is easily formed. Therefore, the fine irregularities having hydroxyl groups and the hydroxyl-containing coating are likely to improve the airtightness and bonding strength of the metal-resin bonded body. Furthermore, when the energy density is equal to or greater than the lower limit, the depth (L) of the recesses of the macro-irregularities formed on the surface of the metal substrate tends to increase, and the aspect ratio (L / D) tends to increase. Therefore, when the resin molded body penetrates into the macro-irregularities, a mechanical bond (anchor effect) between the macro-irregularities and the resin molded body is exerted, which tends to improve the bonding strength. When the energy density is equal to or less than the upper limit, the depth (L) of the recesses of the macro-irregularities formed on the surface of the metal substrate tends to increase, and the aspect ratio (L / D) tends to increase. Therefore, the resin molded body can penetrate deep into the recesses of the macroscopic unevenness, and chemical bonding between the hydroxyl groups of the metal member and the functional groups of the resin molded body is achieved throughout the entire macroscopic unevenness, which facilitates improved airtightness. Furthermore, the protrusions of the macroscopic unevenness can be prevented from becoming elongated and pointed, thereby suppressing a decrease in mechanical strength due to breakage of the protrusions. Furthermore, fracture of the metal member can be prevented when the metal-resin bonded body breaks.

[0058] The laser conditions (laser processing conditions) for laser processing may be appropriately set to achieve the above-mentioned energy density. Parameters of the laser processing conditions include the laser beam output (W), laser beam frequency (kHz), laser beam diameter (μm), laser beam irradiation interval (μm), laser beam scanning speed (mm / s), and the number of laser beam scans. The number of scans refers to the number of times the laser beam is repeatedly applied along the same irradiation path. The relationship between the laser beam diameter and the irradiation interval will be explained with reference to FIG. 2. The laser beam irradiation interval refers to the distance between the path 6 of one laser beam irradiated onto the target object and the path 6' of another laser beam irradiated adjacent to the laser. More specifically, the laser beam irradiation interval refers to the distance between the end of the path 6 of one laser beam on either side in the direction perpendicular to the scanning direction 3 and the end of the path 6' of the other laser beam on the same side as the one laser beam. When a pulsed laser is used, the laser beam path is represented by a continuous path of pores formed by individual laser pulses. In this case, the laser beam irradiation interval 5 corresponds to the sum of the width of the region sandwiched between the trajectories of the laser beam formed by the continuous pores and the size of the beam diameter 4. Table 1 shows examples of laser treatment conditions when the main metal of the metal substrate to be treated with laser is aluminum, iron, or copper.

[0059] [Table 1]

[0060] [2-2. Method for manufacturing metal-resin bonded body] The metal-resin bonded body is produced by molding a resin molded body onto the surface of a metal member using a resin composition as a raw material.

[0061] Here, as a method for molding the resin composition (forming a resin molded body), a suitable molding method can be adopted according to the resin used. For example, when a thermoplastic resin is used, a composition containing a thermoplastic resin is injection-molded onto a metal member to integrally bond the resin molded body to obtain a metal-resin bonded body, or a resin molded body is first obtained by injection molding, and then the obtained resin molded body is integrally bonded to the surface of a metal member 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 thereto.

[0062] Furthermore, for example, when a thermosetting resin is used, examples of methods include, but are not limited to, a metal-resin bonded body obtained by injection-molding a composition containing the thermosetting resin onto a metal member to integrally bond the resin molded body, or a method in which a composition adjusted to a predetermined viscosity is applied onto a metal member and then the metal member is subjected to compression molding by heating and pressurizing the entire body.

[0063] Furthermore, when an adhesive is used, it can be applied to the metal member and dried to harden, but if necessary, operations such as heating can be performed, and molding conditions suitable for the adhesive used can be adopted.

[0064] [3. Action and Effects] It has been previously believed that, in order to increase the bonding strength of metal-resin bonded bodies, it is effective to form macroscopic irregularities with a predetermined opening diameter and depth when treating a metal material with laser light, thereby forming a structure that facilitates mechanical interaction by the resin penetrating. It has also been known that the molten portion of the metal substrate formed by the laser treatment is an oxygen-containing film containing oxygen, and that this oxygen-containing film contributes to the development of bonding strength. After detailed studies, the present inventors have newly discovered that this oxygen-containing film has a structure with fine nano-sized openings (fine irregularities). The inventors have concluded that, in order to further increase the bonding strength and airtightness of metal-resin molded bodies, it is effective to allow the resin to penetrate into these fine irregularities and to effectively utilize the effects of chemical bonding between the functional groups of the oxygen-containing film and the functional groups in the resin. Furthermore, they came to the conclusion that forming such an oxygen-containing film over the entire surface of the joining surface will ensure sufficient interaction between the resin and the oxygen-containing film, and that it will be even more effective to adjust the shape of the macro-irregularities, particularly the depth relative to the opening diameter of the recesses, to create a structure that allows the resin to penetrate relatively easily, while preventing the resin from penetrating too shallowly (so that the interaction between the resin and the oxygen-containing film is not weakened).From this perspective, they discovered that by constructing a joining surface on the surface of a metal substrate, when joined to a resin molded body, a high joining strength can actually be obtained, and a metal resin molded body that can ensure sufficient airtightness can be obtained.

[0065] In the metal member and metal-resin bonded body of the present invention, a hydroxyl-containing film having macro- and micro-relief portions is formed over the entire joining surface. The presence of the hydroxyl-containing film allows 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, the hydroxyl-containing film has macro-relief portions on the order of μm that satisfy a predetermined opening diameter (D), depth (L), and aspect ratio (L / D), thereby providing a mechanical bond (anchor effect) between the macro-relief portions and the resin molded body. Here, the hydroxyl-containing film has macro-relief portions of a predetermined shape, allowing the resin to penetrate deep into the recesses of the macro-relief portions. Furthermore, the hydroxyl-containing film has macro-relief portions on the order of μm in size, and nanometer-order micro-relief portions on the surface of the macro-relief portions. This increases the surface area of ​​the hydroxyl-containing film presented on the joining surface, thereby increasing the amount of hydroxyl groups that interact with the resin molded body. Furthermore, in the metal member and metal-resin bonded body of the present invention, a hydroxyl-containing coating is formed over the entire bonding surface, thereby suppressing a decrease in bonding strength and airtightness that would occur in areas where the hydroxyl-containing coating is not present. Thus, according to the present invention, the effects of mechanical and chemical bonding are exerted over the entire bonding surface, and the metal member and resin molded body can be bonded with the resin permeating the macro-asperity and micro-asperity portions, thereby increasing the area of ​​the bonding surface that contributes to the mechanical and chemical bonding. Therefore, the metal member and metal-resin bonded body of the present invention strengthen the effects of the mechanical and chemical bonding between the metal member and resin molded body, making it possible to improve bonding strength and airtightness.

[0066] In the method for producing a metal member and a metal-resin bonded body of the present invention, a hydroxyl-containing coating having macro-concave and micro-concave portions is formed over the entire surface of the bonding surface by laser treatment, thereby improving the bonding strength and airtightness between the metal member and the resin molded body. In the method for producing a metal member and a metal-resin bonded body of the present invention, the energy density in the laser treatment is 0.5 J / mm 2 As a result, it becomes easier to form a hydroxyl group-containing coating having fine irregularities, and it becomes possible to improve the bonding strength and airtightness between the metal member and the resin molded body. [Example]

[0067] Preferred embodiments of the present invention will be specifically described below based on examples, comparative examples, and test examples, but the present invention should not be construed as being limited thereto.

[0068] [Evaluation method] <Evaluation of joint cross section> Before joining the resin molded body, the metal member or the metal-resin bonded body was cut in the thickness direction, embedded in epoxy resin, and then wet polished to prepare a sample for joint cross-section evaluation. The thickness direction cross-section of the sample for joint cross-section evaluation was observed using a scanning electron microscope (JEOL, JSM-7200F) at magnifications of 100 to 500x. The depth (L) and opening diameter (D) of the macroscopic irregularities were measured from the observed cross-section, and the aspect ratio (L / D) was calculated. Furthermore, the sample for joint cross-section evaluation before joining the resin molded body was cut in the thickness direction and prepared using a cross-section polisher (JEOL, SM-09010) for precision cross-section evaluation. The thickness direction cross-section of the sample for precision cross-section evaluation was observed using a scanning electron microscope (JEOL, JSM-7200F) at magnifications of 50,000x. When a hydroxyl group-containing film was formed over the entire surface of the joining surface, it was evaluated as "entire surface," and when a hydroxyl group-containing film was not formed over the entire surface, it was evaluated as "partial."

[0069] <Evaluation of the surface of metal components before joining> Before bonding the resin molded body to the metal member, the surface was observed using a scanning electron microscope (JEOL Ltd., JSM-7200F) at a magnification of 50,000 times.

[0070] <Evaluation of bonding interface by alkali treatment> A metal-resin bonded body containing aluminum as the primary metal was subjected to an alkali treatment by immersing it in a 5 wt% sodium hydroxide solution at 50°C for 12 hours to completely dissolve the metal, yielding a test resin molded body. The alkali treatment dissolves and removes the metal components of the metal-resin bonded body, leaving behind the resin molded body. After the alkali treatment, the surface of the test resin molded article was observed at a magnification of 50,000 times using a scanning electron microscope (manufactured by JEOL Ltd., JSM-7200F).

[0071] <Evaluation of hydroxyl group-containing film by phosphoric acid chromate treatment> Before resin bonding, metal members (aluminum plates and discs) were immersed in a 1 L solution of chromium phosphate hydroxide, made by adding 35 mL of phosphoric acid, 20 g of chromium (VI) oxide, and distilled water, for 10 minutes at 95 to 100°C to obtain test metal members. In this example, the chromium phosphate treatment was carried out under conditions that remove the hydroxyl groups present on the surface of the micro-irregularities and the hydroxyl group-containing film, while leaving the macro-irregularities undissolved. Next, a resin molded body was joined to the test metal member after the phosphochromate treatment by the method for joining a resin molded body described below, to prepare a test joint after the phosphochromate treatment. The test joints after the phosphoric chromate treatment were evaluated for joint strength and airtightness by the evaluation methods described below. Furthermore, the surfaces of the test metal members before and after the phosphochromate treatment were observed using a scanning electron microscope (JEOL Ltd., JSM-7200F).

[0072] <Evaluation of hydroxyl group-containing coatings obtained by stearic acid treatment> Stearic acid powder was volatilized in an electric furnace maintained at 100°C, and metal members (aluminum plates and discs) before resin bonding were exposed to the stearic acid treatment for 24 hours to obtain test metal members. Next, a resin molded body was joined to the test metal member after the stearic acid treatment by the method for joining a resin molded body described below, to prepare a test joint after the stearic acid treatment. The test joints after the stearic acid treatment were evaluated for joint strength and airtightness by the evaluation methods described below.

[0073] <Evaluation of Bond Strength (1) (Shear Test)> The bond strength of the metal-resin bonded body was evaluated by measuring the shear strength in accordance with ISO 19095. Specifically, as shown in Figure 3, a metal-resin bonded body 9, which was formed by bonding a metal member 8 and a resin molded body 7, was fixed to a dedicated jig 10, and a load was applied at a rate of 10 mm / min so that a shear force was applied in a direction parallel to the bonding surface, and a test was conducted to destroy the bond between the metal member and the resin molded body. The fracture force at which the metal-resin bonded body broke was calculated as the tensile shear strength (MPa).

[0074] Furthermore, the fracture surface on the metal member side after the shear test was visually observed to confirm the fracture mode. If base material fracture occurred in the resin molded body, it was judged as resin fracture (good). If interface fracture occurred between the metal member and the resin molded body, it was judged as interface fracture (poor). If base material fracture occurred in the metal member, it was judged as metal fracture (poor). If fracture was observed between the metal member and the resin bonded body when the resin molded body was released from the mold after injection molding, the shear strength was rated as 0 MPa.

[0075] <Evaluation of Bond Strength (2) (Shear Test)> The bond strength of the metal-resin-metal bonded bodies was evaluated by measuring shear strength in accordance with JIS K 6850. Specifically, as shown in FIG. 4, a metal-resin-metal bonded body 11, which was formed by bonding two metal members 8 and 8' using a thermosetting adhesive (described below), was fixed to a dedicated jig 10, and a load was applied at a rate of 5 mm / min so that a shear force was applied in a direction parallel to the bonded surfaces, in order to fracture the bonded portion of the bonded body between the metal members via the adhesive. The fracture strength at which the metal-resin-metal bonded body broke was calculated as the tensile shear strength (MPa).

[0076] Furthermore, the fracture surface after the evaluation of the shear strength was visually observed to confirm the fracture mode. When cohesive failure occurred with the adhesive and the adhesive remained throughout the joint, it was judged as "resin failure" (good). When interfacial failure occurred between the metal member and the adhesive, it was judged as "interfacial failure" (bad).

[0077] <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. 5, with the metal-resin joint 9 formed by joining the metal member 8 and the resin molded body 7 clamped and fixed in the dedicated airtight jig 15, air was applied up to 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. 6, with the metal-resin-metal joint 11 formed by bonding two metal members 8 and 8' using the thermosetting adhesive described later clamped and fixed in the dedicated airtight jig 15, air was applied up to 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 above-mentioned dedicated airtight jig 15, the metal-resin joint 9 or the metal-resin-metal joint 11 is sandwiched and fixed from above and below by fixing jigs with an O-ring 13 interposed. With the metal-resin joint 9 or the metal-resin-metal joint 11 sandwiched, water 12 exists in the upper open part of the dedicated airtight jig 15, and air exists in the lower sealed part of the dedicated airtight jig 15. By applying air to the sealed part through the ventilation pipe 14, it is possible to confirm whether air leaks to the open part side through the metal-resin joint 9 or the metal-resin-metal joint 11 by using as a mechanism whether bubbles are generated from the joint interface. In the case where there is no air leak within the evaluation time, it was evaluated as "qualified (good)", and in the case where air leak was observed, it was evaluated as "unqualified (bad)".

[0078] <GD-OES surface analysis> Surface analysis was performed on the metal member before joining the resin molded body using a glow discharge optical emission spectrometry (GD-OES) (manufactured by Horiba, Ltd.: GD-Profiler2). The measurement conditions were as follows: analysis diameter (anode diameter): 4 mmφ, gas pressure: 600 Pa, RF output: 35 W, sampling interval: 0.1 s, measured elements: Al (measurement wavelength 396.157 nm, high voltage of photomultiplier tube 600 V), measured element: Fe (measurement wavelength 374.954 nm), measured element: Cu (measurement wavelength 324.759 nm), measured element: OH group (measurement wavelength 306.775 nm, high voltage of photomultiplier tube 900 V). Also, the measurement method was to perform elemental analysis by sputtering the sample with Ar plasma and causing the sputtered atoms to emit atomic light, and calculate the hydroxyl group presence rate from the emission intensity detected within the range until the time required for 200 nm sputtering corresponding to the main elements (Al, Cu, Fe) constituting the metal member elapsed after the metal member or hydroxyl group was detected. Regarding the time required for 200 nm sputtering, each standard sample containing the above elements in high purity (Al: A995 manufactured by Nippon Light Metal Co., Ltd., Cu: Cu-113514 manufactured by Nilaco Corporation, Fe: Fe-223469 manufactured by Nilaco Corporation) was measured in advance under the same apparatus and analysis conditions as above, and was determined from the obtained sputtering rate (μm / min). The purity of each standard material, as well as the sputtering rate of each standard material and the time required for 200 nm sputtering, are as shown in Table 2 below.

[0079]

Table 2

[0080] <EPMA Cross-section Mapping> Cross-sectional mapping of the metal components before bonding to the resin molded body was performed using an electron probe microanalyzer (EPMA) (Shimadzu Corporation: EPMA-1610). Measurement conditions included an irradiation diameter of 40 μm / step, with 512 steps measured in both the vertical and horizontal 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. The detected oxygen intensity was then calculated as a weight percentage (wt%) using a calibration curve prepared in advance. The calibration curve was prepared by calculating the oxygen intensity of an Al2O3 standard sample (oxygen content: 48 wt%) and the oxygen intensity of high-purity Al foil.

[0081] [Example 1] <Production of metal components> A rectangular aluminum plate measuring 1.5 mm thick x 18 mm wide x 45 mm long and a circular aluminum disk measuring 2 mm thick x 55 mm outer diameter x 20 mm inner diameter were cut out from a hollow extrusion of A6063 aluminum alloy (A6063-T5) that had been treated in accordance with ISO 19095 and with the tempering code T5 specified in JIS H0001.

[0082] Next, the processed surfaces of these aluminum plates and aluminum disks were subjected to laser processing under the following conditions to form a bonding surface with the resin molded product. For the aluminum plates, the laser was irradiated in a striped pattern on a rectangular area measuring 10 mm in the longitudinal direction and 18 mm in the lateral direction at the longitudinal end of one main surface. For the aluminum disks, the laser was irradiated concentrically from the inside to a 2.0 mm wide annular area. The laser processing conditions are summarized in Table 5 below. <Laser treatment conditions> Equipment: Keyence 3Axis Fiber laser marker (model: MDF-5200) Laser wavelength: 1090nm Transmission method: Pulse Output: 42.5W Frequency: 60kHz Beam diameter: 60μm Irradiation interval: 90μm Scanning speed: 320mm / s Number of scans (irradiations): 1 Energy density: 1.48J / mm 2

[0083] <Joining of resin molded bodies, production of metal-resin bonded bodies> Each metal member (the laser-treated aluminum plate and aluminum disk) with the bonding surfaces formed as described above was inserted into a mold fabricated in accordance with ISO 19095 using an injection molding machine (Nissei Plastic Industrial Co., Ltd., FNX1103-18A). Then, the molded body was injection-molded with an aromatic nylon (Mitsubishi Engineering-Plastics Corporation, trade name: Reny®, grade: XL1002U) based on polyamide MXD10 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. This produced a bonded member (metal-resin bonded member 9, Figure 7) between aluminum plate (metal member) 8 and resin molded body 7. The bonded member had a rectangular shape measuring 3 mm thick, 10 mm wide, and 45 mm long, and the bonding area of ​​the rectangular joint between the aluminum plate and resin molded body was 5 mm x 10 mm. The resin molded body is a disk-shaped body 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 of the aluminum disk is 2.0 mm and the joining area is 138.2 mm. 2 A bonded body (metal-resin bonded body 9, FIG. 8) of an aluminum disk (metal member) 8 and a resin molded body 7 was produced.

[0084] <Evaluation> The cross section of the metal-resin bonded structure was evaluated. Figure 9 shows the results of SEM observation of the cross section. Specifically, for the 12 consecutive recesses shown in Figure 9, the third recess from the right marked with a white dashed line c was designated as the lowest recess Pb1, and a reference line RL1 was drawn passing through Pb1. Furthermore, the convex portion through which the white solid line H passes 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 perpendicular to RL2 from the lowest portion of each of the 12 recesses, indicated by dashed lines a to l. Then, parallel median lines were drawn midway between adjacent dashed lines a to l, indicated by solid lines A to K. Finally, the depths L1 to L10 and opening diameters D1 to D10 were measured as shown in the figure. The measured values ​​were as shown in Tables 3 and 4. Next, the obtained measurement values ​​were subjected to the Smirnoff-Grubbs test using the procedure described above to detect outliers. As shown in Table 4, the p-value for opening 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, excluding the recess corresponding to D10 where the outlier was detected, the average values ​​of L1 to L9 and D1 to D9 were used as the depth (L) and opening diameter (D), respectively, in Example 1, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6.

[0085] [Table 3]

[0086] [Table 4]

[0087] FIG. 10 shows the results of SEM observation for precise cross-sectional evaluation. Furthermore, the surfaces of the metal members after the laser treatment were evaluated before joining. The results of observation of the surfaces of the metal members after the laser treatment are shown in Figure 11. The metal-resin bonded body was also subjected to an alkali treatment to evaluate the bonded interface. 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 formed by the phosphochromate treatment on the metal members before resin bonding was evaluated. The results of SEM observation of the surface of the metal members after the phosphochromate treatment are shown in Figure 13. Table 7 shows the evaluation results of the bonding strength and airtightness before and after the phosphochromate treatment. Furthermore, the hydroxyl group-containing coating was evaluated by exposing the metal members to stearic acid before resin bonding. The evaluation results for bonding strength and airtightness before and after stearic acid treatment are shown in Table 7. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6. Surface analysis was also performed using GD-OES. The results of the GD-OES measurements are shown in Figure 14. From the time when the emission intensity derived from aluminum and hydroxyl groups was detected until the 3.33 seconds required for 200 nm sputtering had elapsed, the amount of aluminum detected was 39.7 and the amount of hydroxyl groups detected was 3.6. The hydroxyl group abundance rate was calculated to be 8.31%. Furthermore, cross-sectional mapping was performed using an EPMA. The measurement results using the EPMA are shown in Figure 15.

[0088] [Example 2] The metal used was A5052 aluminum alloy (A5052-H34) treated with the tempering symbol H34 specified in JIS H0001. The laser treatment conditions were as follows: output 50 W, irradiation interval 110 μm, scanning speed 400 mm / s, energy density 1.14 J / mm 2 Metal members (aluminum plates and aluminum disks) were produced in the same manner as in Example 1, except for the above change, and metal-resin bonded bodies for evaluation were also produced. The metal-resin bonded body was evaluated for its cross section. The results of cross-sectional observation by SEM are shown in Figure 16. The evaluation was performed in the same manner as in Example 1, and L1 to L10 and D1 to D10 were measured and subjected to the Smirnoff-Grubbs test, but no outliers were detected. Therefore, the average values ​​of L1 to L10 and D1 to D10 were used as the depth (L) and opening diameter (D), respectively, in Example 2, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6. Furthermore, the surfaces of the metal members after the laser treatment were evaluated before joining. The results of observation of the surfaces of the metal members after the laser treatment are shown in Figure 17. The metal-resin bonded body was also subjected to an alkali treatment to evaluate the bonded interface. The results of observation of the surface of the resin molded body after alkali treatment are shown in Figure 18. Furthermore, the hydroxyl group-containing coating formed by the phosphochromate treatment on the metal members before resin bonding was evaluated. The evaluation results of the bond strength and airtightness before and after the phosphochromate treatment are shown in Table 7. The results of SEM observation of the surface of the metal member after the phosphochromate treatment are shown in Figure 19. Furthermore, the hydroxyl group-containing coating was evaluated by exposing the metal members to stearic acid before resin bonding. The evaluation results for bonding strength and airtightness before and after stearic acid treatment are shown in Table 7. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0089] [Example 3] The laser processing conditions were a scanning speed of 400 mm / s and an energy density of 1.18 J / mm 2 Metal members (aluminum plates and aluminum disks) were produced, and metal-resin bonded bodies for evaluation were also produced in the same manner as in Example 1, except that the resin composition was changed to the above and that polyphenylene sulfide (PPS) (manufactured by Polyplastics Co., Ltd., trade name: DURAFIDE, grade: 1150MF1) was used as the thermoplastic resin. The metal-resin bonded body was evaluated for its cross section. The results of cross-sectional observation by SEM are shown in Figure 20. Evaluation was performed using the same method as in Example 1. L1 to L10 and D1 to D10 were measured, and a Smirnoff-Grubbs test was performed. The p-value for the opening diameter D1 was 0.024 (2.4%), so D1 was excluded. The same test was then performed again on D2 to D10 after the exclusion. No outliers were detected. Therefore, the average values ​​of L2 to L10 and D2 to D10, excluding the recess corresponding to D1 where the outlier was detected, were used as the depth (L) and opening diameter (D), respectively, in Example 3, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0090] [Example 4] The metal used was a rolled material of oxygen-free copper (C1020) specified in JIS H3100. The laser processing conditions were a scanning speed of 400 mm / s, a number of scans of 5, and an energy density of 5.90 J / mm. 2 Metal members (copper sheets and copper disks) were produced in the same manner as in Example 1, except that the resin composition was changed to the above, and polyphenylene sulfide (PPS) (manufactured by Polyplastics Co., Ltd., trade name: DURAFIDE, grade: 1150MF1) was used as the thermoplastic resin, and metal members (copper sheets and copper disks) and metal-resin bonded bodies for evaluation were produced in the same manner as in Example 1. The bonded cross section of the laser-treated metal member before bonding the resin molded article was evaluated. The results of SEM observation of the cross section are shown in Figure 21. The evaluation was performed using the same method as in Example 1, measuring L1-10 and D1-10, and performing the Smirnoff-Grubbs test, but no outliers were detected. Therefore, the average values ​​of L1-L10 and D1-D10 were used as the depth (L) and opening diameter (D), respectively, in Example 4, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0091] [Example 5] Two rectangular aluminum plates measuring 5 mm thick x 25 mm wide x 50 mm long were cut out from hollow extrusions of A6063 aluminum alloy (A6063-T5) treated to the tempering code T5 specified in JIS H0001, a circular aluminum disk measuring 2 mm thick x 55 mm outer diameter x 20 mm inner diameter, and a circular aluminum disk measuring 2 mm thick x 24 mm outer diameter were cut out and used as metal substrates.

[0092] Next, the laser processing conditions were as follows: irradiation interval: 70 μm, scanning speed: 500 mm / s, energy density: 1.21 J / mm 2 Laser irradiation was performed in the same manner as in Example 1, except that the laser irradiation conditions were changed to the following: 1) Laser irradiation was performed to form a joining surface. For the two aluminum plates, a 6 mm x 25 mm rectangular region was irradiated with a striped laser at the longitudinal end of one of the main surfaces. For the annular aluminum disk, a 2.0 mm wide annular region was irradiated with a laser from the inside in a concentric manner. For the circular aluminum disk, a 2.0 mm wide region was irradiated with a laser from the outer periphery in a concentric manner.

[0093] A thermosetting adhesive (one-component heat-curing epoxy adhesive) (product name: Scotch-Weld® SW2214, manufactured by 3M Japan Ltd.) was applied to the joining surfaces of each metal component (laser-treated aluminum plate and aluminum disk) with a thickness of 0.2 mm, adjusted with a stainless steel wire. After applying the adhesive, the two aluminum plates were bonded together, and a pressure of 0.01 MPa was applied. After the specimen temperature reached 150°C, the test pieces were heated for 30 minutes. This resulted in a rectangular joint of the two aluminum plates (metal components) 8 and 8' (a joint of an aluminum plate, a resin molded body, and an aluminum plate) with an adhesive-bonded area of ​​6 mm × 25 mm (metal-resin-metal joint 11, Figure 22). In addition, after applying the adhesive, a circular aluminum disk and a circular aluminum disk were bonded together, and under the same bonding conditions, the bonding width of the circular joint between the circular aluminum disk and the circular aluminum disk was 2.0 mm and the bonding area was 138.2 mm. 2A bonded body (a bonded body of a circular aluminum disk, a resin molded body, and a circular aluminum disk) (metal-resin-metal bonded body 11, Figure 23) was produced by bonding an annular aluminum disk (metal member) 8 and a circular aluminum disk (metal member) 8' via an adhesive. The bonded cross section of the metal-resin-metal bonded body was evaluated. The results of cross-sectional observation by SEM are shown in Figure 24. Evaluation was performed using the same method as in Example 1, and L1 to L10 and D1 to D10 were measured and subjected to the Smirnoff-Grubbs test, but no outliers were detected. Therefore, the average values ​​of L1 to L10 and D1 to D10 were used as the depth (L) and opening diameter (D), respectively, in Example 5, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0094] [Example 6] The metal used was a rolled material of oxygen-free copper (C1020) specified in JIS H3100. The laser treatment conditions were as follows: irradiation interval: 70 μm, scanning speed: 400 mm / s, number of scans: 5, energy density: 7.59 J / mm 2 Metal members (copper sheets and copper disks) were produced in the same manner as in Example 1, except that the resin composition was changed to the above, and polyphenylene sulfide (PPS) (manufactured by Polyplastics Co., Ltd., trade name: DURAFIDE, grade: 1150MF1) was used as the thermoplastic resin, and metal members (copper sheets and copper disks) and metal-resin bonded bodies for evaluation were produced in the same manner as in Example 1. The laser-treated metal members before joining the resin molded articles were evaluated for their joint cross sections. The results of SEM observation of the cross sections are shown in Figure 25. Evaluation was performed using the same method as in Example 1. L1-10 and D1-10 were measured, and a Smirnoff-Grubbs test was performed. The p-value for depth L2 was 0.030 (3.0%), so L2 was excluded. The same test was then performed again on L1 and L3-L10 after excluding them. No outliers were detected. Therefore, the average values ​​of L1 and L3-L10, and D1 and D3-D10, excluding the recess corresponding to L2 where the outlier was detected, were used as the depth (L) and opening diameter (D) in Example 6, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0095] [Example 7] The metal used was stainless steel plate (SUS304), and the laser processing conditions were: scanning speed 340 mm / s, number of scans 2, energy density 2.78 J / mm 2 Metal members (iron plates and iron disks) were produced, and metal-resin bonded bodies for evaluation were also produced in the same manner as in Example 1, except that the resin composition was changed to the above and that polyphenylene sulfide (PPS) (manufactured by Polyplastics Co., Ltd., trade name: DURAFIDE, grade: 1150MF1) was used as the thermoplastic resin. The laser-treated metal members before joining the resin molded articles were evaluated for their joint cross sections. The results of SEM observation of the cross sections are shown in Figure 26. Evaluation was performed using the same method as in Example 1. L1-10 and D1-10 were measured and a Smirnoff-Grubbs test was performed. The p-value for depth L6 was 0.022 (2.2%), so L6 was excluded. The same test was then performed again on L1-L5 and L7-L10 after excluding them. No outliers were detected. Therefore, the average values ​​of L1-L5 and L7-L10, and the average values ​​of D1-D5 and D7-D10, excluding the recess corresponding to L6 where the outlier was detected, were used as the depth (L) and opening diameter (D) in Example 7, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0096] [Comparative Example 1] The metal used was A5052 aluminum alloy (A5052-H34) treated with the tempering symbol H34 specified in JIS H0001. The laser treatment conditions were as follows: irradiation interval 120 μm, output 50 W, frequency 90 kHz, scanning speed 400 mm / s, laser energy density 1.04 J / mm 2 Metal members (aluminum plates and aluminum disks) were produced in the same manner as in Example 1, except for the above change, and metal-resin bonded bodies for evaluation were also produced. The bonded cross section of the metal-resin bonded body was evaluated. The results of cross-sectional observation by SEM are shown in Figure 27. The evaluation was performed in the same manner as in Example 1, and L1 to L10 and D1 to D10 were measured and subjected to the Smirnoff-Grubbs test, but no outliers were detected. Therefore, the average values ​​of L1 to L10 and D1 to D10 were taken as the depth (L) and opening diameter (D) in Comparative Example 1, respectively, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6. As can be seen from FIG. 27, in Comparative Example 1, there were areas in the central parts of the surfaces of the projections that were not covered with the hydroxyl group-containing film due to the absence of laser irradiation. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0097] Comparative Example 2 The metal used was a rolled material of oxygen-free copper (C1020) specified in JIS H3100. The laser processing conditions were as follows: output 42.5 W, frequency 60 kHz, irradiation interval 90 μm, scanning speed 100 mm / s, number of scans 5, energy density 23.6 J / mm 2 Metal members (copper plates and copper disks) were produced in the same manner as in Example 1, except for the above change, and metal-resin bonded bodies for evaluation were also produced. The laser-treated metal members before joining the resin molded articles were evaluated for their joint cross sections. The results of SEM observation of the cross sections are shown in Figure 28. Evaluation was performed using the same method as in Example 1. L1-10 and D1-10 were measured, and a Smirnoff-Grubbs test was performed. The p-value for the opening diameter D10 was 0.036 (3.6%), so D10 was excluded. The same test was then performed again on D1-D9 after the exclusion. No outliers were detected. Therefore, the average values ​​of L1-L9 and D1-D9, excluding the recess corresponding to D10 where the outlier was detected, were used as the depth (L) and opening diameter (D) for Comparative Example 2, respectively, to calculate the aspect ratio (L / D). The measurement results are shown in Table 6. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0098] Comparative Example 3 The metal used was A5052 aluminum alloy (A5052-H34) treated with the tempering symbol H34 specified in JIS H0001. The laser treatment conditions were as follows: output 15 W, frequency 60 kHz, irradiation interval 90 μm, scanning speed 340 mm / s, energy density 0.49 J / mm 2 Metal members (aluminum plates and aluminum disks) were produced in the same manner as in Example 1, except for the above change, and metal-resin bonded bodies for evaluation were also produced. The cross section of the laser-treated metal member before joining the resin molded article was evaluated. The results of SEM observation of the cross section are shown in Figure 29. Evaluation was performed using the same method as in Example 1. L1 to L10 (not shown in the figure) and D1 to D10 were measured and a Smirnoff-Grubbs test was performed, but no outliers were detected. Therefore, the average values ​​of L1 to L10 and D1 to D10 were used as the depth (L) and opening diameter (D), respectively, for Comparative Example 3, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6. Although L1 to L10 are not explicitly shown in the figure, the corresponding points on the dashed lines b to k were designated as L1 to L10, as in the other cross-sectional observation diagrams (the same applies to Comparative Examples 4 to 6). As can be seen from FIG. 29, in Comparative Example 3, there were areas in the central parts of the surfaces of the projections that were not covered with the hydroxyl group-containing film due to the absence of laser irradiation. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0099] Comparative Example 4 The laser processing conditions were: output 42.5 W, frequency 60 kHz, irradiation interval 70 μm, scanning speed 3000 mm / s, energy density 0.20 J / mm 2 Laser irradiation was carried out in the same manner as in Example 5, except that the above-mentioned change was made to form a bonding surface. The metal-resin-metal bonded body was evaluated for its cross section. The results of cross-sectional observation by SEM are shown in Figure 30. Evaluation was performed using the same method as in Example 1, measuring L1-10 and D1-10, and performing the Smirnoff-Grubbs test. No outliers were detected. Therefore, the average values ​​of L1-L10 and D1-D10 were used as the depth (L) and opening diameter (D), respectively, in Comparative Example 4, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0100] Comparative Example 5 The metal used was a rolled material of oxygen-free copper (C1020) specified in JIS H3100. The laser processing conditions were as follows: output 35 W, frequency 60 kHz, irradiation interval 70 μm, scanning speed 800 mm / s, laser energy density 0.63 J / mm 2 Metal members (copper sheets and copper disks) were produced in the same manner as in Example 1, except that the resin composition was changed to the above, and polyphenylene sulfide (PPS) (manufactured by Polyplastics Co., Ltd., trade name: DURAFIDE, grade: 1150MF1) was used as the thermoplastic resin, and metal members (copper sheets and copper disks) and metal-resin bonded bodies for evaluation were produced in the same manner as in Example 1. The laser-treated metal members before joining the resin molded articles were evaluated for their joint cross sections. The results of SEM observation of the cross sections are shown in Figure 31. Evaluation was performed using the same method as in Example 1. L1-10 and D1-10 were measured and subjected to a Smirnoff-Grubbs test. The p-value for the opening diameter D3 was 0.036 (3.6%), and the p-value for the depth L6 was 0.047 (4.7%). Therefore, D3 and L6 were excluded. The same test was then performed again on L1-L5 and L7-L10, as well as D1, D2, and D4-D10. No outliers were detected. Therefore, the average values ​​of L1, L2, L4, L5, and L7-L10, and the average values ​​of D1, D2, D4, D5, and D7-D10, excluding the recesses corresponding to D3 and L6 where the outliers were detected, were used as the depth (L) and opening diameter (D) for Comparative Example 5, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0101] Comparative Example 6 The metal used was stainless steel plate material (SUS304), and the laser processing conditions were as follows: output 42.5 W, frequency 60 kHz, irradiation interval 90 μm, scanning speed 2000 mm / s, energy density 0.24 J / mm 2 Metal members (iron plates and iron disks) were produced in the same manner as in Example 1, except for the above change, and metal-resin bonded bodies for evaluation were also produced. The bonded cross section of the laser-treated metal member before bonding the resin molded article was evaluated. The results of SEM observation of the cross section are shown in Figure 32. The evaluation was performed using the same method as in Example 1, measuring L1-10 and D1-10, and performing the Smirnoff-Grubbs test, but no outliers were detected. Therefore, the average values ​​of L1-L10 and D1-D10 were used as the depth (L) and opening diameter (D), respectively, in Comparative Example 6, and the aspect ratio (L / D) was calculated. The measurement results are shown in Table 6. The metal-resin bonded bodies were also evaluated for bonding strength and airtightness. The evaluation results are shown in Table 6.

[0102] [Table 5]

[0103] [Table 6]

[0104] [Table 7]

[0105] [Consider] Cross-sectional observation of the metal-resin joined bodies or metal members of Examples 1 to 7 by SEM confirmed that macroscopic irregularities having micrometer-order irregularities were formed over the entire joining surface. It was also confirmed that the resin penetrated into the macroscopic irregularities to form the bond. Cross-sectional observation of the metal member of Example 1 by TEM confirmed that nanometer-order fine irregularities were formed on the surface of the macroscopic irregularities.

[0106] Surface observation by SEM of the metal members before bonding in Examples 1 and 2 also confirmed that macro-convexo-concave portions and micro-concave portions were formed on the surfaces of the metal members. Furthermore, surface observation by SEM of the test resin molded body after the alkali treatment in Examples 1 and 2 confirmed that the surface of the resin molded body remaining after dissolving and removing the metal members had nanometer-order irregularities that resembled a replica of the micro-concave portions. These results confirmed that in the metal-resin bonded body, the resin penetrated into the micro-concave portions and was bonded.

[0107] Surface observations by SEM before and after the phosphochromate treatment in Examples 1 and 2 confirmed that the phosphochromate treatment removed the microscopic irregularities, while leaving the macroscopic irregularities. Furthermore, after the phosphochromate treatment in Examples 1 and 2, the shear strength was slightly lower than before the phosphochromate treatment. Furthermore, after the phosphochromate treatment in Examples 1 and 2, the airtightness evaluation failed. Furthermore, after the stearic acid treatment in Examples 1 and 2, the shear strength was slightly lower than before the stearic acid treatment. Furthermore, after the stearic acid treatment in Examples 1 and 2, the airtightness evaluation failed. These results suggest that a certain level of shear strength was maintained regardless of the presence or absence of microscopic irregularities, and therefore, it is believed that the mechanical bonding (anchor effect) provided by the macroscopic irregularities contributes primarily to the development of the joining strength of the metal-resin bonded body. Furthermore, regardless of whether or not the shape of the fine concave-convex portions was present, the airtightness test failed when there were no hydroxyl groups. Therefore, it is believed that the airtightness of the metal-resin bonded body is mainly due to chemical bonding through hydrogen bonding between the hydroxyl groups present on the surface of the metal member and the functional groups contained in the resin.

[0108] The hydroxyl group presence rate calculated by surface analysis using GD-OES confirmed the presence of oxygen atoms and hydroxyl groups near the surface. Furthermore, cross-sectional mapping using EPMA revealed that oxygen elements were localized in the outermost surface layer of the metal component. These results confirmed that the surface of the metal component was provided with a hydroxyl-containing coating containing hydroxyl groups.

[0109] Cross-sectional observation of the metal-resin bonded bodies or metal members of Examples 1 to 7 using an SEM confirmed that macro-convexo-concave portions having predetermined opening diameters (D) and depths (L) and aspect ratios (L / D) within a predetermined range were formed. Furthermore, the metal-resin bonded bodies of Examples 1 to 7 satisfied the shear strength values, and resin fracture occurred at the bonded portions, confirming that the bond between the metal and resin had sufficient bond strength. Furthermore, Examples 1 to 7 also passed the airtightness evaluation.

[0110] The above evaluation results revealed that the metal members and metal-resin joined bodies of Examples 1 to 7 had joining surfaces on the surfaces of the metal members where a hydroxyl-containing coating having macro-concave and micro-concave portions was formed over the entire surface. It was also confirmed that the metal members and metal-resin joined bodies of Examples 1 to 7 had good joining strength and airtightness.

[0111] On the other hand, in Comparative Examples 1 and 3, cross-sectional observation using an SEM confirmed that, between the recesses formed by laser irradiation, there remained unirradiated areas that were not irradiated with the laser and were not covered with deposits resulting from laser irradiation (e.g., reference numeral 17 in Figure 27). That is, in Comparative Examples 1 and 3, unirradiated areas remained on the joining surfaces of the metal members, and it was confirmed that the hydroxyl-containing coating was partially absent and partially formed. In other words, in Comparative Examples 1 and 3, the surface of the metal member did not have a joining surface on which a hydroxyl-containing coating was formed over the entire surface. In the unirradiated areas, the surface of the metal member was covered with an oxide coating, so no interaction occurred between the hydroxyl groups of the hydroxyl-containing coating and the resin. Furthermore, in Comparative Examples 1 and 3, macroscopic irregularities were not formed over the entire joining surface. Therefore, it is believed that in Comparative Examples 1 and 3, the mechanical bond with the resin was weakened in the unirradiated areas, resulting in interfacial failure at the joining interface. In addition, in Comparative Example 1, it is believed that the chemical bond with the resin was weakened in the laser-unirradiated portions, resulting in insufficient airtightness.

[0112] Furthermore, in Comparative Example 2, cross-sectional observation using an SEM confirmed the formation of macroscopic irregularities with an aspect ratio (L / D) exceeding the upper limit of a predetermined range. In this case, the concave portions of the macroscopic irregularities were extremely tapered from the openings toward the depths. Furthermore, the convex portions of the macroscopic irregularities had a long, pointed structure. Therefore, in Comparative Example 2, it was difficult for the resin to penetrate deep into the concave portions of the macroscopic irregularities, weakening the chemical bond with the resin at the depths of the concave portions, resulting in insufficient airtightness. Furthermore, in Comparative Example 2, it was believed that the convex portions of the macroscopic irregularities broke, weakening the mechanical bond with the resin, resulting in destruction of the metal member at the bonded portion.

[0113] In Comparative Examples 3 to 6, cross-sectional observation using an SEM confirmed the formation of macroscopic irregularities with aspect ratios (L / D) below the lower limit of the specified range. In these cases, the relatively shallow depth of the concave portions of the macroscopic irregularities prevented the resin from penetrating into the resin, resulting in insufficient anchoring, leading to interfacial failure. Furthermore, in Comparative Examples 3 to 6, the surface area of ​​the hydroxyl-containing coating exposed on the joining surface was reduced, resulting in a reduced number of hydroxyl groups interacting with the resin molded body, resulting in failed airtightness evaluations. [Explanation of symbols]

[0114] 1...Highest convex part Pt1, 2...Lowest concave part Pb1, 3...Scanning direction, 4...Beam diameter, 5...Irradiation interval, 6 (6')...Laser light trajectory, 7...Resin molded body, 8 (8')...Metal member, 9...Metal-resin bonded body, 10...Special jig for shear test, 11...Metal-resin-metal bonded body, 12...Water, 13...O-ring, 14...Air blowing tube, 15...Special airtight jig, 16...Fine concave-convex part (oxygen-containing film), 17...Laser-unirradiated part

Claims

1. A metal member having a joining surface for joining objects on its surface, The metal member includes a metal substrate made of metal and a hydroxyl group-containing coating that contains hydroxyl groups and is formed on the surface of the metal substrate; the hydroxyl group-containing coating is formed over the entire surface of the joining surface, The hydroxyl group-containing coating has a macro-irregularity on its surface, which is composed of a plurality of irregularities, each having an opening diameter (D) of 20 μm to 200 μm, a depth (L) of 20 μm to 200 μm, and an aspect ratio (L / D) of the opening diameter (D) to the depth (L) of 0.5 to 5, and the micro-irregularity on the surface of the macro-irregularity has a plurality of openings of 10 nm to 50 nm and a thickness of 10 nm to 1000 nm.

2. The metal component according to claim 1, characterized in that when the hydroxyl-containing coating is analyzed by glow discharge optical emission spectroscopy from the surface in the depth direction, the ratio of the detected amount of hydroxyl groups to the total amount of the detected amount of metal in the metal substrate and the detected amount of hydroxyl groups is 4% or more.

3. 3. The metal member according to claim 1, wherein the metal is aluminum, copper, iron, or an alloy containing any of these metals.

4. A metal member described in any one of claims 1 to 3, characterized in that the fine uneven portion is a spongy structure having the openings.

5. A metal component described in any one of claims 1 to 4, characterized in that the metal is aluminum or an alloy containing aluminum.

6. A metal-resin joined body comprising at least one metal member according to any one of claims 1 to 5 and at least one resin molded body on a surface of the metal member, wherein the metal member and the resin molded body are joined via the joining surface in a state in which the resin has penetrated into the macro-convexo-concave portion and the micro-concaveo-concave portion.

7. 7. The metal-resin bonded body according to claim 6, wherein the resin molded body contains a thermoplastic resin or a thermosetting resin.

8. A method for manufacturing a metal member having a surface to be joined with an object to be joined, a film-forming step of forming a hydroxyl group-containing film on the surface of a metal substrate by laser treatment in which a laser beam is irradiated onto the surface of the metal substrate; In the film forming step, the joining surface is formed with the hydroxyl group-containing film formed over the entire surface by the laser treatment, In the film formation step, the laser treatment forms the hydroxyl-containing film on its surface, which has a macroscopic unevenness consisting of a plurality of unevennesses, each having an opening diameter (D) of 20 μm to 200 μm, a depth (L) of 20 μm to 200 μm, and an aspect ratio (L / D) of the opening diameter (D) to the depth (L) of 0.5 to 5, and the entire surface of the macroscopic unevenness has a plurality of openings of 10 nm to 50 nm, and the hydroxyl-containing film has a microscopic unevenness on its surface, which has a thickness of 10 nm to 1000 nm.

9. In the film forming process, the energy density in the laser treatment is 0.5 J / mm 2 9. The method for manufacturing a metal member according to claim 8, wherein the above-mentioned steps are carried out.

10. 10. The method for manufacturing a metal member according to claim 8 or 9, characterized in that in the film formation process, the hydroxyl-containing film is formed by the laser treatment, such that when analysis is performed from the surface in the depth direction by glow discharge optical emission spectrometry, the ratio of the detected amount of hydroxyl groups to the total amount of the detected amount of metal and the detected amount of hydroxyl groups in the metal base material is 4% or more.

11. A method for manufacturing a metal component described in any one of claims 8 to 10, characterized in that the fine uneven portion is a spongy structure having the openings.

12. The metal is aluminum, copper, iron, or an alloy containing any of these metals, In the film forming step, the energy density (J / mm2) in the laser treatment is expressed by the following formula (A1) using the output W (W) of the laser light, the number of laser light scans N (times), the laser light irradiation interval C (mm), the laser light scanning speed V (mm / s), the length (Length) of the laser irradiated portion perpendicular to the irradiation direction of the laser light, and the width (Width) of the laser irradiated portion parallel to the irradiation direction of the laser light: Energy density=(((Length / C)×Width×N) / V)×W) / (Length×Width) Formula (A1) In the coating formation step, the energy density (J / mm 2 ) in the laser treatment is calculated by formula (A2) obtained by modifying formula (A1), Energy density = (W × N) / (C × V) Equation (A2) A method for manufacturing a metal component as described in any one of claims 8 to 11, characterized in that in the coating formation process, when laser treatment is performed on a metal substrate whose main metal is aluminum, the energy density of the laser treatment is 0.5 J / mm 2 or more and 4 J / mm 2 or less, when laser treatment is performed on a metal substrate whose main metal is iron, the energy density of the laser treatment is 1 J / mm 2 or more and 10 J / mm 2 or less, and when laser treatment is performed on a metal substrate whose main metal is copper, the energy density of the laser treatment is 2 J / mm 2 or more and 20 J / mm 2 or less.

13. A method for manufacturing a metal component according to any one of claims 8 to 12, characterized in that the metal is aluminum or an alloy containing aluminum.

14. After obtaining a metal component by the method according to any one of claims 8 to 13, a resin molding step is then included in which a resin molded body is bonded to a surface of the obtained metal component, A method for producing a metal-resin joined body including at least one metal member and at least one resin molded body, A method for producing a metal-resin bonded body, characterized in that the metal member and the resin molded body are bonded via the bonding surface in a state in which the resin has penetrated into the macro-convex and micro-concave portions.

15. 15. The method for producing a metal resin bonded body according to claim 14, wherein in the resin molding step, a resin composition containing a thermoplastic resin or a thermosetting resin is molded onto the metal members.

Images