METAL COMPONENT PRODUCTION METHOD AND METAL-RESIN BOND PRODUCTION METHOD

Abstract

To provide a method for manufacturing a metal member and a metal resin molding for obtaining a metal resin molding which has high joint strength, is reduced in breakage on a joint interface between a metal member and a resin molding, and is excellent in adhesiveness.SOLUTION: There are provided a method for manufacturing a metal member which includes an irradiation step of forming a metal molten layer generated by melting and solidifying a metal substrate made of metal by irradiation of the surface of the metal substrate with a laser beam, and manufactures a metal member where the metal molten layer is formed on the surface of the metal substrate, wherein the irradiation step forms a joined surface where the metal molten layer having an uneven part is formed over the whole surface, on the surface of the metal substrate, laser irradiation density of the laser beam is 0.2 J / mm2 or more and 1.9 J / mm2 or less, a beam diameter (D0) of the laser beam is 20-200 μm, and a ratio (D / D0) of an opening diameter (D) in the uneven part to the beam diameter (D0) is 1.1 or less; and a method for manufacturing a metal resin joined body using the same.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a metal member having a specific joining surface, and a method for manufacturing a joined body of the metal member and a resin molded body. [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 provide 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, the bonding strength of resin joints is insufficient because unevenness is not formed, leaving room for further improvement in the treatment method. In contrast, the methods described in Patent Documents 1 to 3, which use laser light, are advantageous in that they can form unevenness, but 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 unevenness is not formed, resulting in a decrease in bonding strength and difficulty in ensuring airtightness, which also leaves room for further improvement.

[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 pores or grooves, "protrusions" consisting of burrs are formed on both sides of the openings of the pores or grooves, and these "protrusions" are embedded in the resin molded body to enhance the joining strength. Patent Document 5 also discloses laser processing conditions for forming a joint between a metal surface and a resin by performing laser scanning on the metal surface in one scanning direction and then laser scanning in an intersecting scanning direction. While this creates an uneven joint, it is preferable to form some of the joints as a "bridge shape" in which the protrusions are connected to each other in an arch shape with a hole at the bottom, or to form the protrusions as "overhanging" in a mushroom or cedar tree shape, thereby enhancing the anchoring effect between dissimilar materials at the joint. Furthermore, Patent Document 6 discloses a method for manufacturing a composite member in which an aluminum die-cast member having a carbide film formed on its surface is irradiated with a laser to remove the carbide film and melt the surface layer of the joining surface, thereby integrally molding a polymer member onto the joining surface. [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] Patent No. 4020957 [Patent Document 6] Patent No. 6568983 Summary of the Invention [Problem to be solved by the invention]

[0007] In Patent Document 4, there are laser-unirradiated areas sandwiched between the protrusions made up of burrs that make up the protrusion group. The presence of such laser-unirradiated areas may cause a decrease in the bonding strength (and at the same time, airtightness may not be ensured). In addition, in Patent Document 5, laser scanning is required in two intersecting directions, which leaves room for improvement in that the processing time is too long, and there is also room for improvement in that there are laser-unirradiated areas (untreated areas) at the bottom of the "bridge shape," which is considered to be a preferred shape, which may decrease the bonding strength (and airtightness). Furthermore, in Patent Document 6, when the laser irradiation density is 2 J / mm 2 More than 40J / mm 2 The high irradiation density conditions below pose a problem in that they cause significant damage to metals.

[0008] The object of the present invention is to provide a metal resin molded body having high bonding strength, little fracture at the bonding interface between the metal member and the resin molded body, and excellent adhesion, and a method for manufacturing a metal member to obtain the same. [Means for solving the problem]

[0009] That is, the gist of the present invention is as follows. [1] A method for manufacturing a metal member, comprising an irradiation step of forming a metal molten layer by irradiating a surface of a metal substrate made of metal with laser light to melt and solidify the metal substrate, and manufacturing a metal member having the metal molten layer formed on the surface of the metal substrate, In the irradiation step, a joining surface is formed on the surface of the metal base material, and the metal melting layer having an uneven portion is formed over the entire surface of the joining surface, In the irradiation step, the laser irradiation density of the laser light is 0.2 J / mm 2 More than 1.9J / mm 2 is as follows: The laser irradiation density (J / mm 2 ) is the theoretical total energy of the laser light (J), the beam area of the laser light (mm 2 ), the frequency of the laser beam (Hertz (Hz)), the theoretical printing time of the laser beam (s), and the measured printing time of the laser beam (s), are expressed by the following formulas (A1) to (A3): The beam diameter (D0) of the laser light is 20 μm to 200 μm, A method for manufacturing a metal member, wherein a ratio (D / D0) of an opening diameter (D) in the concave-convex portion to the beam diameter (D0) is 1.1 or less. Laser irradiation density = a × b (A1) a = theoretical total energy / (beam area x frequency x theoretical printing time) (A2) b = Theoretical printing time / Actual printing time (A3) [2] In the irradiation step, the laser irradiation density of the laser light is 0.22 J / mm 2 More than 1.9J / mm 2 The method for producing a metal member according to [1], characterized in that: [3] The theoretical total energy is expressed by the product of the laser light output (J / s) and the theoretical printing time (s) using the following formula (A4): The theoretical printing time is calculated based on the set area (mm 2 ), the number of laser beam scans (times), the laser beam irradiation interval (mm), and the laser beam scanning speed (mm / s), are represented by the following formula (A5): Theoretical total energy = (output x theoretical printing time) (A4) Theoretical printing time = (set area x number of irradiations) / (irradiation interval x scanning speed) (A5) [ 4 ] The uneven portion is characterized in that at least one of the adjacent convex portions has a structure protruding toward the concave portion side. [1] ~[3] The method for manufacturing the metal member according to claim 1. [ 5 ] [1] to [2], characterized in that the scanning speed of the laser light is 200 mm / s to 2000 mm / s 4 10. A method for producing a metal member according to any one of the preceding claims. [ 6 ] The metal is aluminum, copper, iron, or an alloy containing any of these metals [1] to [ 5 10. A method for producing a metal member according to any one of the preceding claims. [ 7 ][1]~[ 6 a resin molding step of forming a resin molded body on a surface of the metal member obtained by the manufacturing method according to any one of the preceding items. A method for producing a metal-resin joined body in which the metal base material and the resin molded body are joined via the metal fusing layer, comprising: The resin composition shape a step of joining the metal member and the resin molded body together in a state where the resin has penetrated into the uneven portions at the joining surfaces. [ 8The resin molded body is characterized in that it contains a thermoplastic resin or a thermosetting resin. 7 ] A method for producing a metal-resin bonded body according to the above. [Effects of the Invention]

[0010] The method for producing a metal member and a metal-resin bonded body of the present invention can provide a metal-resin bonded body having excellent adhesion, in which the bonding strength between the metal member and the resin molded body is high and there is little fracture at the bonding interface between the metal member and the resin bonded body. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the relationship between the laser irradiation section, the laser movement section, and the switching positions therebetween. [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 schematic diagram showing how to determine the opening diameter (D) and depth (L) in the concave-convex portion. [Figure 4] FIG. 4 is a diagram for explaining an outline of the bonding strength evaluation (1) (shear test). [Figure 5] FIG. 5 is a diagram for explaining an outline of the bonding strength evaluation (2) (shear test). [Figure 6] FIG. 6 is a diagram showing an outline of a metal-resin-metal bonded body for evaluation of bonding strength. [Figure 7] FIG. 7 is a diagram (photograph) of the joint cross section of the metal-resin-metal joint body produced in Example 1, observed with a scanning electron microscope (SEM). [Figure 8] FIG. 8 is a diagram (photograph) of the joint cross section of the metal-resin-metal joint body produced in Example 2, observed with an SEM. [Figure 9] FIG. 9 is a diagram (photograph) of the joint cross section of the metal-resin-metal joint body produced in Example 3, observed with an SEM. [Figure 10] FIG. 10 is a diagram showing an outline of a metal-resin bonded body for evaluation of bonding strength. [Figure 11]FIG. 11 is a diagram (photograph) of the joint cross section of the metal-resin joined body produced in Example 4, observed with an SEM. [Figure 12] FIG. 12 is a diagram (photograph) of the joint cross section of the metal-resin joined body produced in Example 5, observed with an SEM. [Figure 13] FIG. 13 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 14] FIG. 14 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 15] FIG. 15 is a diagram (photograph) of the joint cross section of the metal-resin-metal joint body produced in Example 8, observed with an SEM. [Figure 16] FIG. 16 is a diagram (photograph) of a joint cross section of the metal-resin-metal bonded body produced in Comparative Example 1, observed with an SEM. [Figure 17] FIG. 17 is a diagram (photograph) of a joint cross section of the metal-resin-metal bonded body produced in Comparative Example 2, observed with an SEM. [Figure 18] FIG. 18 is a diagram (photograph) of a joint cross section of the metal-resin-metal bonded body produced in Comparative Example 3, observed with an SEM. DETAILED DESCRIPTION OF THE INVENTION

[0012] The method for producing the metal member and the metal-resin bonded body of the present invention will be described in detail below. The components of the present invention described below can be combined in part or in whole as appropriate.

[0013] [Metal member and method for manufacturing a metal-resin bonded body] The method for producing a metal member of the present invention includes an irradiation step of irradiating a surface of a metal substrate made of metal with laser light to form a metal fusion layer caused by melting and solidifying the metal substrate. This produces a metal member having a joining surface formed on the surface of the metal substrate, the joining surface being covered with the metal fusion layer having irregularities. The method for producing a metal-resin joined body of the present invention also includes a resin molding step of joining a resin molded body to the surface of the metal member.

[0014] [1.Metal component manufacturing method] <Metal base material> First, the metal substrate used in the manufacture of 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] <Preparation process> The method for manufacturing a metal member of the present invention may include a preparation step of performing pretreatment such as degreasing treatment, etching treatment, desmutting treatment, chemical polishing treatment, and electrolytic polishing treatment as pretreatment of the surface of the metal substrate prior to the irradiation step.

[0016] <Irradiation process> The present invention includes an irradiation step in which 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 joining surface on the surface of the metal substrate, in which a metal melt layer having irregularities is formed over the entire surface, thereby obtaining the metal member of the present invention. 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.

[0017] The joining surface is a joining surface with an object to be joined, and may be formed on only a portion of one surface of the metal substrate, or on the entire surface, or on part or all of both surfaces. The joining surface may be formed in a necessary portion depending on the intended use. Furthermore, there are no particular limitations on the shape, size, arrangement, etc. of the joining surface. The same applies to combined materials, etc. In the present invention, the "joining surface" refers to the region where the metal substrate and resin are to be joined, and refers to the region where a predetermined treatment has been applied to the surface of the metal substrate for joining with the resin. In contrast, the region where the metal substrate and resin are joined is referred to as a "joint" to distinguish it from the "joint."

[0018] The joining object to be joined to the metal substrate is not particularly limited as long as it is made of a material that can be joined to 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 joining object is preferably a resin molded body made of a resin material. The resin molded body will be described later.

[0019] (Formation of a molten metal layer) The principle of forming a metal fusion layer in the irradiation process 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 is partially or completely oxidized to become metal oxide, which accumulates and solidifies around the irradiated areas that become recesses, forming protrusions. A deposit (metal fusion layer) made of metal oxide is formed in the form of a film that covers the recesses and protrusions. In this way, the deposit made of metal oxide formed on the surface of the metal substrate forms a metal fusion layer that forms the uneven shape of the uneven parts. The state of the formation of the metal fusion layer can be confirmed, for example, by dissolving the metal fusion layer using alkaline etching treatment, which allows it to be distinguished from an insoluble metal substrate. Note that metal oxides have at least some partial ionicity, and metal ions (Al 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.

[0020] In addition, if there is a laser-unirradiated portion of the metal member that is not irradiated with a laser, no metal melt layer is present in the laser-unirradiated portion. Typically, an oxide film is formed in the laser-unirradiated portion. Since the laser-unirradiated portion does not have a metal melt layer, if the laser-unirradiated portion is flat, improvement in the bonding strength due to mechanical bonding caused by unevenness cannot be expected. Therefore, if a laser-unirradiated portion remains on the bonding surface and a metal melt layer is not formed on the entire bonding surface, the bonding strength of the metal-resin bonded body will decrease, and there is a risk of fracture at the bonding interface. Therefore, in the present invention, a metal melt layer is formed over the entire bonding surface of the metal member. In addition, since the hydroxyl group-containing film described above is not present in the laser-unirradiated portion, interaction due to chemical bonding caused by hydroxyl groups cannot be expected.

[0021] As described above, the uneven portion formed in the metal melt layer has a structure consisting of recesses formed by perforating the metal substrate upon irradiation with laser light and protrusions formed by deposits of metal oxides upon irradiation with laser light. Multiple laser beam irradiations adjacent to each other result in a repeating structure consisting of recesses and protrusions. Such uneven portions can be confirmed by observing the surface or cross section of the metal member using, for example, a scanning electron microscope (SEM). The structure of the uneven portion will be described later.

[0022] (Laser treatment conditions) In the irradiation step, the laser treatment conditions for forming a metal melt layer having irregularities are set as follows. First, laser processing is affected by the laser irradiation density, which is the energy density of the laser itself. The laser irradiation density is the unit area (1 mm 2 ) is the laser output given by one pulse of a pulsed laser (per pulse duration), and is the theoretical total energy of the laser light (J), the beam area of the laser light (mm 2 ), the frequency of the laser beam (Hertz (Hz)), the theoretical printing time of the laser beam (s), and the measured printing time of the laser beam (s), are expressed by the following formulas (A1) to (A3). Laser irradiation density (J / mm 2 )=a×b (A1) a = theoretical total energy / (beam area x frequency x theoretical printing time) (A2) b = Theoretical printing time / Actual printing time (A3) Here, the theoretical total energy is expressed by the product of the laser light output (J / s) and the theoretical printing time (s) using the following formula (A4). Theoretical total energy = (output x theoretical printing time) (A4) The theoretical printing time is also calculated based on the set area (mm 2It is expressed by the following formula (A5) using the total area treated with laser light including unirradiated areas), the number of laser light scans (times), the laser light irradiation interval (mm), and the laser light scanning speed (mm / s). Theoretical printing time = (set area x number of irradiations) / (irradiation interval x scanning speed) (A5)

[0023] As shown in Equation (A2), a in Equation (A1) calculates the (true) laser irradiation density per unit area during the period when the laser is turned on for one pulse of the pulsed laser when scanning a target with a laser at a given laser beam output. In contrast, as shown in Figure 1, there are actually two sections of the target (workpiece) 4 where the laser beam output is turned on and irradiated (laser irradiation section (black arrow, symbol 1)) and where the laser is simply moved without irradiation (turned off) (laser movement section (white arrow, symbol 2)). The arrows in Figure 1 indicate the direction of laser movement. At the transition point between these sections (symbol 3), the laser beam output is turned off. However, the faster the laser scanning speed, the longer the braking time, which in turn extends the time the laser output is turned off. Therefore, the time during which the laser output is turned off must be taken into consideration. Therefore, by calculating the ratio (above b) of the time the output of the laser light is ON (theoretical printing time) to the total time the output of the laser light is ON and OFF (actual printing time), and multiplying this by (a), the (apparent) laser irradiation density in the present invention can be obtained.

[0024] In the present invention, the laser irradiation density of the above formula (A1) is 0.2 J / mm 2 More than 1.9J / mm 2 The preferred lower limit is 0.22 J / mm 2 and a more preferable lower limit is 0.24 J / mm 2 and a more preferable lower limit is 0.3 J / mm 2 The preferred upper limit is 1.5 J / mm 2 and a more preferable upper limit is 1.2 J / mm 2and a more preferable upper limit is 1 J / mm 2 As the laser irradiation density increases, the concave portions of the uneven portion in the metal melt layer formed on the surface of the metal substrate tend to become deeper, resulting in increased surface roughness of the metal component after laser processing. Therefore, by setting the laser irradiation density within the above range, uneven portions having a shape in which some of the convex portions protrude toward the concave portions can be formed while satisfying the relationship between the beam diameter (D0) of the laser light and the opening diameter (D) of the concave portions, as described below, and the fitting effect due to the penetration of the resin or the like to be joined tends to be more easily achieved. Note that the higher the melting point and the greater the thermal diffusion of the metal constituting the metal substrate, the less susceptible the metal substrate tends to be to the effects of the laser light. Taking the above circumstances into consideration, it is desirable to change the laser irradiation density according to the metal to be laser-treated.

[0025] When performing laser processing on a metal substrate whose main metal is aluminum, the laser irradiation density is usually 0.2 J / mm 2 or more, preferably 0.22 J / mm 2 More than 0.23J / mm 2 More preferably, 0.24 J / mm 2 or more, and a particularly preferable lower limit is 0.3 J / mm 2 When performing laser treatment on a metal substrate containing aluminum as the main metal, the laser irradiation density is preferably 1.9 J / mm 2 Less than or equal to 1.5 J / mm 2 Less than or equal to 1.2 J / mm 2 The upper limit is preferably 1 J / mm 2 is.

[0026] When performing laser processing on a metal substrate containing iron as the main metal, the laser irradiation density is preferably 0.23 J / mm 2 More than 0.24J / mm 2 More preferably, 0.3 J / mm 2In addition, when performing laser treatment on a metal substrate containing iron as the main metal, the laser irradiation density is preferably 1.9 J / mm 2 Less than or equal to 1.5 J / mm 2 Less than or equal to 1.2 J / mm 2 The upper limit is preferably 1 J / mm 2 is.

[0027] When laser processing is performed on a metal substrate containing copper as the main metal, the laser irradiation density is preferably 0.23 J / mm 2 More than 0.24J / mm 2 More preferably, 0.3 J / mm 2 In addition, when performing laser treatment on a metal substrate containing copper as the main metal, the laser irradiation density is preferably 1.9 J / mm 2 Less than or equal to 1.5 J / mm 2 Less than or equal to 1.2 J / mm 2 The upper limit is preferably 1 J / mm 2 is.

[0028] When the laser irradiation density is equal to or greater than the lower limit, a metal melt layer having the predetermined irregularities described below is easily formed on the surface of the laser-treated metal member. Furthermore, irregularities can be formed in which some of the protrusions protrude toward the recesses, which facilitates the penetration of the resin or other materials to be joined, thereby providing a fitting effect. Therefore, the joining strength of the metal-resin bonded body is improved, and fracture at the bonding interface is reduced. When the energy density is equal to or less than the upper limit, excessively large recess depths (L) of the irregularities formed on the surface of the metal substrate can be prevented, which can lead to linear slopes (i.e., shapes that do not protrude toward the recesses) and excessively large aspect ratios (L / D). Therefore, the resin molded body penetrates deep into the recesses of the irregularities, and the fitting effect is easily achieved. Furthermore, the protrusions of the irregularities can be prevented from becoming elongated and pointed, which can prevent 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 fractures.

[0029] In the present invention, the beam diameter D0 of the laser light is set to 20 μm to 200 μm. By setting the beam diameter D0 to 20 μm or more, it is possible to prevent the unevenness that is formed from becoming excessively fine, and also to shorten the laser processing time for the bonding area. .Ma Furthermore, by setting the beam diameter D0 to 200 μm or less, it is possible to prevent the unevenness formed from becoming excessively large, and to prevent the laser irradiation density from becoming excessively small. The lower limit of the beam diameter D0 is preferably 30 μm, more preferably 40 μm, and even more preferably 50 μm. The upper limit of the beam diameter D0 is preferably 150 μm, more preferably 100 μm, and even more preferably 80 μm.

[0030] The laser conditions (laser processing conditions) for the laser processing may be appropriately set to achieve the above-mentioned laser irradiation density. Parameters of the laser processing conditions include the laser beam output (J / s), the laser beam frequency (kHz), the laser beam diameter (μm), the laser beam irradiation interval (μm), the 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 8 of one laser beam irradiated onto the target object and the path 8' 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 of the one laser beam on either side in the direction perpendicular to the scanning direction 5 and the end of the path of the other laser beam on the same side as the one laser beam. When a pulsed laser is applied, the path of the laser beam is represented by a continuous path of pores formed by individual laser pulses. In this case, the laser beam irradiation interval 7 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 6. 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.

[0031] [Table 1]

[0032] The scanning speed of the laser beam is preferably 200 mm / s or more, more preferably 300 mm / s or more, even more preferably 400 mm / s or more, particularly preferably 500 mm / s or more, and preferably 2000 mm / s or less, more preferably 1500 mm / s or less, even more preferably 1200 mm / s or less, and particularly preferably 1000 mm / s or less. When the scanning speed of the laser beam is equal to or greater than the above-mentioned lower limit, it is easy to prevent the depth (L) of the recesses from becoming excessively large due to localized concentration of the laser beam, resulting in narrow recesses. Furthermore, the irradiation area per unit time increases, thereby shortening the laser processing time and facilitating efficient laser processing. When the scanning speed of the laser beam is equal to or less than the above-mentioned upper limit, the time during which the laser beam output is ON becomes relatively longer compared to the total time during which the laser beam output is ON and OFF, which makes it easy to increase the laser irradiation density. Furthermore, it is easy to prevent the depth (L) of the recesses from becoming excessively small, resulting in shallow recesses.

[0033] In the present invention, the laser beam is irradiated so that the ratio D / D0 of the beam diameter D0 of the laser beam to the opening diameter (D) formed (described below) is 1.1 or less. D / D0 is preferably 1 or less, more preferably 0.8 or less, even more preferably 0.7 or less, and particularly preferably 0.5 or less. The lower limit of D / D0 is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. By irradiating the laser beam so that D / D0 is equal to or less than the upper limit, it is possible to prevent the recess from becoming too shallow relative to the opening diameter. In other words, it is possible to prevent the recess from becoming a shape that weakens the interlocking effect between the metal member and the resin even if the resin flows into the recess. In other words, the anchor effect between the metal member and the resin is more easily exhibited, and a cross-sectional structure exhibiting strong adhesion in the shear direction can be obtained. By irradiating the laser beam so that D / D0 is equal to or greater than the above-mentioned lower limit, it becomes easier to prevent the depth of the recesses from becoming excessively large relative to the opening diameter, the sloped surfaces of the protrusions from becoming linear, and the aspect ratio (L / D) from becoming excessively large. Therefore, the resin molded body penetrates deep into the recesses of the uneven portion, and the interlocking effect is easily achieved. Furthermore, it is possible to prevent the structure of the protrusions of the uneven portion from becoming elongated and pointed, thereby suppressing a decrease in mechanical strength due to breakage of the protrusions, etc. Furthermore, it is possible to prevent fracture of the metal member when the metal-resin bonded body is fractured.

[0034] (Uneven part) The uneven portion formed in the metal melt layer is a structure having an uneven shape of the order of μm. The uneven portion has a predetermined opening diameter (D) and depth (L) determined by the procedure shown in Figure 3.

[0035] Here, to calculate the opening diameter (D) and depth (L), a cross section of the joint of the metal member or the metal-resin joint was observed using an SEM, and the opening diameter and depth of the recess with the largest opening diameter among multiple recesses included in the observed SEM cross section were evaluated as the opening diameter (D) and depth (L) of the present invention. In this way, in the present invention, by evaluating the opening diameter (D) and depth (L) using the recess with the largest opening diameter, which tends to be the weakest interaction between the metal member and the resin, as a representative, it is possible to evaluate whether the interaction between the metal member and the resin is exerted over the entire joint surface.

[0036] Specifically, as shown in Figure 3, this is determined by drawing the following lines on the cross-sectional photograph. First, the deepest points of the two recesses located on either side of one protrusion (this will be called "protrusion 1") are designated as Pb1 and Pb2. The center position of the line segment connecting Pb1 and Pb2 is designated as center point Pcb1. Similarly, for the protrusion adjacent to protrusion 1 (this will be called "protrusion 2"), Pb2 and Pb3 are designated, and the center position of the line segment connecting these two points is designated as center point Pcb2.

[0037] Next, a reference line L1 (white dashed line) is drawn perpendicularly from Pcb1 of convex 1 toward the surface of the molten metal layer. Similarly, a reference line L2 is drawn from Pcb2 of convex 2. The points at which these reference lines L1 and L2, drawn toward the surface of the molten metal layer, first reach the surface of the molten metal layer at each convex portion are designated Pct1 and Pct2, respectively. Note that Pct1 and Pct2 are not necessarily the highest points of each convex portion, and may be located on the inclined surfaces of the convex portions, as shown in the cross-sectional views in the examples described below.

[0038] Next, reference lines L21 and L22 are drawn connecting the determined points Pct1 and Pct2 and the deepest point Pb2 of the recess between protrusions 1 and 2. The point on the surface of the molten metal layer within the region between reference lines L21 and L22 where the length (thickness, height) from reference line L21 to the surface of the molten metal layer is longest is designated Pr1, and the point on the surface of the molten metal layer where the length (thickness, height) from L22 to the surface of the molten metal layer is longest is designated Pr2. Here, the length from reference line L21 to Pr1 is designated L31, and the length from reference line L22 to Pr2 is designated L32. If each of the lengths L31 and L32 is 3 μm or greater, Pr1 and Pr2 are designated as the opening reference points. On the other hand, if the lengths L31 and L32 are less than 3 μm, the center points Pct1 and Pct2 are designated as the opening reference points.

[0039] Next, the highest points Pt1 and Pt2 are taken, which are the highest positions on each of the convex portions 1 and 2. Note that, as mentioned above, Pt1 and Pt2 do not necessarily coincide with the above-mentioned Pct1 and Pct2. Then, a reference line L4 is drawn connecting these highest points Pt1 and Pt2. From the reference line L4, reference lines L51 and L52 perpendicular to the reference line L4 are drawn toward the opening reference points (Pr1 and Pr2 in Figure 3) of each of the convex portions 1 and 2.

[0040] The distance between these reference lines L51 and L52 is defined as the opening diameter (D) of the recess, and the recess with the largest opening diameter among the multiple recesses is defined as the opening diameter (D) of the concave-convex portion of the metal base material to be used. The distance between the deepest point Pb2 of the recess and the reference line L4, in the direction perpendicular to the reference line L4 from the deepest point Pb2, is defined as the depth of the recess.

[0041] In the present invention, the opening diameter (D) determined in this manner is preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 40 μm or more. The opening diameter (D) is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 70 μm or less.

[0042] In addition to ensuring that the opening diameter (D) falls within this numerical range, it is preferable that at least one of the adjacent convex portions of the concave-convex portion has a structure that protrudes toward the concave portion. That is, it is preferable that the convex portion has a structure in which at least one of L31 and L32 in FIG. 3 is 3 μm or more, so that the inclined surface is not linear but protrudes toward the concave portion, resulting in a nonlinear, random structure. The present invention is also characterized in that the opening diameter (D) of the concave portion is determined taking such a structure into consideration. With such a structure, the contact area between the surface of the concave-convex portion (metal melting layer) and the resin to be joined is increased, and therefore, an effective interlocking effect can be expected.

[0043] In the present invention, the depth (L) is preferably 20 μm or more, more preferably 40 μm or more, and even more preferably 50 μm or more. The depth (L) is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. In addition, the aspect ratio (L / D) of the opening diameter (D) to the depth (L) is preferably 0.3 or more, more preferably 0.5 or more, and even more preferably 1 or more. The aspect ratio (L / D) is preferably 5 or less, more preferably 4 or less, and even more preferably 3 or less.

[0044] (Hydroxy group-containing film) It is desirable that a hydroxyl group-containing coating containing hydroxyl groups be present on the outermost surface of the metal fusion layer due to the irradiation of the laser light.

[0045] Such a 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).

[0046] The presence of a hydroxyl-containing coating can be confirmed by detecting hydroxyl groups near the outermost surface of the molten metal layer of the metal member using, for example, glow discharge optical emission spectrometry (GD-OES). Specifically, first, the emission intensity (V) derived from the main metal and hydroxyl groups constituting the metal substrate is measured in the thickness direction at the joining surface of the metal member using GD-OES. Next, the detected amount of the main metal constituting the metal substrate is calculated from the integrated value (area) of the emission intensity derived from the main metal. The detected amount of hydroxyl groups is also measured from the integrated value of the emission intensity derived from hydroxyl groups. Furthermore, the ratio of the detected amount of hydroxyl groups to the total amount of the detected amount of the main metal and the detected amount of hydroxyl groups is calculated as the hydroxyl group abundance. In the emission spectrum obtained by GD-OES, the peaks appearing at 281 nm and 309 nm are considered to be peaks derived from hydroxyl groups. Measurement of the emission intensity near the surface of the metal member 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.

[0047] 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. By ensuring that 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 in some cases, it is expected that they will interact with functional groups contained in the resin molded body or other object to be joined. This also tends to improve the bonding strength of the metal-resin joined body. 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 content is preferably 30% or less, more preferably 20% or less, even more preferably 15% or less, and particularly preferably 10% or less.

[0048] (Fine unevenness of hydroxyl group-containing film) The surface of the hydroxyl-containing coating has a fine irregularity. The fine irregularity is a structure having an irregular shape of nm order size, and is formed on the surface of the hydroxyl-containing coating. The fine irregularity is formed on the surface of the hydroxyl-containing coating when a metal fusion layer having the hydroxyl-containing coating is formed by laser irradiation. The fine irregularity can be confirmed by observing the surface or cross section of the metal member using, for example, a scanning electron microscope (SEM).

[0049] 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.

[0050] [2. Method for manufacturing metal-resin bonded body] After the metal member is manufactured as described above, a resin molding step is then carried out to form a resin molded body on the surface (joint surface) of the metal member, thereby manufacturing a metal-resin joined body.

[0051] <Resin molding process> 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.

[0052] 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.

[0053] 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.

[0054] <Resin molded body> The resin molded body contains a thermoplastic resin or a thermosetting resin. 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] <Metal-resin bonded body> A metal-resin bonded body is formed with the resin penetrating into the bonding surface (metal melting layer, uneven portion) 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 each of the metal member and the resin molded body, or a plurality of either or both may be bonded, or a plurality of sets thereof may be laminated in any order, and this can be determined appropriately depending on the application.

[0061] 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.

[0062] 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.

[0063] [3. Action and Effects] It has been previously believed that increasing the bonding strength of metal-resin bonded bodies can be achieved by treating a metal material with laser light to form irregularities with a predetermined opening diameter and depth, thereby creating a structure that facilitates mechanical interaction through the infiltration of resin. It has also been known that the molten portion of the metal substrate formed by the laser treatment is an oxygen-containing film, and that this oxygen-containing film contributes to the development of bonding strength. After extensive research, the inventors have discovered that in order to increase the bonding strength of metal-resin molded bodies and reduce fracture at the bonding interface, it is necessary for the metal member and the resin molded body to be bonded via a predetermined metal melting layer at the bonding surface. Specifically, a metal melting layer must be formed over the entire bonding surface, and this metal melting layer must have irregularities with a predetermined opening diameter (D), thereby achieving a fitting effect in which the resin penetrates the irregularities and is bonded. It has been discovered that this method allows the metal member and the resin bonded body to be bonded with high bonding strength and reduces fracture at the bonding interface.

[0064] In the method for manufacturing a metal member and a metal-resin bonded body of the present invention for obtaining such a metal-resin bonded body, by setting the laser irradiation density of the laser light within a predetermined range and the beam diameter D0 of the laser light within a predetermined range, a metal melt layer having a predetermined concave-convex portion can be easily formed. That is, a concave-convex portion can be formed in which a portion of the convex portion protrudes toward the concave portion, thereby easily achieving a fitting effect due to the penetration of the resin or other object to be bonded. Furthermore, it is easy to prevent the concave depth (L) of the concave-convex portion formed on the surface of the metal substrate from becoming excessively large, resulting in the inclined surface of the convex portion becoming linear (a shape that does not protrude toward the concave portion) or an excessively large aspect ratio (L / D). In addition, by preventing the convex portion of the concave-convex portion from becoming elongated and pointed, a decrease in mechanical strength due to, for example, breaking of the convex portion can be suppressed. Furthermore, it is possible to prevent fracture at the interface between the metal member and the resin molded body when the metal-resin bonded body fractures.

[0065] Furthermore, by irradiating the laser beam under conditions where the ratio (D / D) of the opening diameter (D) to the beam diameter (D) is below the upper limit, it is possible to prevent the depth from becoming too small compared to the opening diameter (D), resulting in a shallow recess. In other words, it is possible to prevent the recess from becoming a shape that weakens the fitting effect between the metal member and the resin even if the resin flows into the recess.

[0066] Therefore, the present invention can provide a metal-resin bonded body having high bonding strength between the metal member and the resin molded body, little fracture at the bonding interface between the metal member and the resin bonded body, and excellent adhesiveness.

[0067] Here, although there have been documents that disclose the laser irradiation density (for example, Patent Document 6), the definition of the laser irradiation density in these documents is not clear and is not uniquely determined, so the laser processing conditions that can improve the bonding strength have not been clarified.

[0068] In the present invention, the laser irradiation density is calculated using the sum of the time the laser light output is on and the time it is off (actually measured printing time). This allows the present invention to take into account the effect of a decrease in laser irradiation density that occurs when the time the laser output is off increases as the scanning speed increases, making it possible to evaluate the relationship between laser processing conditions and the bonding state in a more realistic manner. Note that the definition of the laser irradiation density specified in Patent Document 6 is not clear, but it is understood to be different from the laser irradiation density in the present invention, which takes into account the actual printing time.

[0069] In addition, in the present invention, the uneven portion has a structure in which at least one of the adjacent protrusions protrudes toward the recessed portion, which makes it easier for the resin or other object to be joined to penetrate and achieve a fitting effect. [Example]

[0070] 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.

[0071] [Evaluation method] <Evaluation of joint cross section> The metal member before joining the resin molded body or the metal-resin joined body was cut in the thickness direction, embedded in epoxy resin, and then wet polished to prepare a sample for evaluation of the joint cross section. The cross section of the sample for evaluation of the joint cross section in the thickness direction was observed with a scanning electron microscope (JEOL, JSM-7200F) at a magnification of 100 to 500 times. The depth (L) of the uneven part and the opening diameter (D) were measured from the observed cross section.

[0072] <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 4, a metal-resin bonded body 12, which was formed by bonding a metal member 10 and a resin molded body 9, was fixed to a dedicated jig 11, 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).

[0073] Furthermore, the fracture surface on the metal member side after the shear test was visually observed to confirm the fracture morphology. The ratio of the area of the resin cohesive failure to the total area of the resin molded body where base material failure occurred and the interfacial failure between the metal member and the resin molded body (resin cohesive failure rate (%)) was calculated. If fracture was observed between the metal member and the resin joined body when the resin molded body was released from the mold after injection molding, the shear strength was recorded as 0 MPa.

[0074] <Evaluation of Bond Strength (2) (Shear Test)> The bond strength of the metal-resin-metal bonded body was evaluated by measuring shear strength with reference to JIS K 6850. Specifically, as shown in Figure 5, a metal-resin-metal bonded body 13, which was made by bonding two metal members 10 and 10' using a thermosetting adhesive (described below), was fixed to a dedicated jig 11, 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, and a test was conducted to destroy the bonded portion of the bonded body between the metal members via the adhesive. The breaking force at which the metal-resin-metal bonded body broke was calculated as the tensile shear strength (MPa).

[0075] Furthermore, the fracture surface after the shear strength evaluation was visually inspected to confirm the fracture morphology. The percentage of the area where resin cohesive failure occurred was calculated as the ratio of the area where resin cohesive failure occurred to the total area of the bonded surface, which included the area where resin cohesive failure occurred and the area where interfacial failure occurred between the metal member and the adhesive.

[0076] [Example 1] <Production of metal components> Two rectangular aluminum plates measuring 5 mm thick x 25 mm wide x 50 mm long were cut out from a plate-shaped member of aluminum alloy die-cast (ADC12) specified in JIS H5302 and prepared as metal substrates.

[0077] Next, the surfaces of these aluminum plates were subjected to laser processing under the following conditions to form a bonding surface for the resin molded product. For the aluminum plates, the laser was irradiated in a striped pattern on a rectangular area measuring 6 mm in the longitudinal direction and 25 mm in the lateral direction at the longitudinal end of one of the main surfaces. The laser processing conditions are summarized in Table 2 below. <Laser treatment conditions> Equipment: Keyence 3Axis Fiber laser marker (model: MDF-5200) Laser wavelength: 1090nm Transmission method: Pulse Power output: 42.5J / s Frequency: 60kHz Beam diameter: 60μm ·Irradiation interval: 70μm Scanning speed: 300mm / s Number of scans (irradiations): 1 ·Theoretical printing time: 7.143s Actual printing time: 7,410 seconds Laser irradiation density: 0.24J / mm 2

[0078] <Joining of resin molded bodies, production of metal-resin-metal joints> 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 two metal members (aluminum plates after laser processing) with a bonded surface formed. The adhesive was applied to the joining surfaces using a stainless steel wire to achieve a thickness of 0.2 mm. 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 between the two aluminum plates 10 and 10' (a joint of aluminum plate, resin molded body (adhesive), and aluminum plate) with a bonded area of 6 mm × 25 mm (metal-resin-metal joint 13, Figure 6).

[0079] <Evaluation> The resulting metal-resin-metal bonded body was evaluated for its cross section. The results of cross-sectional observation using an SEM are shown in Figure 7. Specifically, for protrusions 1 and 2 shown in Figure 7, the deepest points Pb1, Pb2, and Pb3 were taken as the deepest positions of the recesses located on both sides of each protrusion. The center position of the line segment connecting Pb1 and Pb2 was taken as center point Pcb1, and the center position of the line segment connecting Pb2 and Pb3 was taken as center point Pcb2.

[0080] Next, a reference line L1 was drawn perpendicularly from Pcb1 on convex 1 toward the surface of the molten metal layer, and similarly a reference line L2 was drawn from Pcb2 on convex 2. The points at which these reference lines L1 and L2 first reached the surface of the molten metal layer on each convex are shown as Pct1 and Pct2, respectively.

[0081] Next, reference lines L21 and L22 were drawn connecting the previously determined points Pct1 and Pct2 with the deepest point Pb2 of the recess between convexities 1 and 2. At this time, the length from reference line L21 to other surfaces of the molten metal layer was almost nonexistent, and a length of 3 μm or more could not be ensured, so point Pr1 could not be determined. Therefore, Pct1 was designated as the opening reference point for convexity 1. On the other hand, since the length (thickness, height) L32 from L22 to the surface of the molten metal layer was 3 μm or more, point Pr2 on the surface of the molten metal layer was selected, and therefore Pr2 was designated as the opening reference point for convexity 2.

[0082] Next, the highest points Pt1 and Pt2 of each convex 1 and convex 2 were taken, and a reference line L4 was drawn connecting these highest points Pt1 and Pt2. From the reference line L4, reference lines L51 and L52 perpendicular to the reference line L4 were drawn toward the opening reference points (Pct1 and Pr2) of each convex 1 and convex 2.

[0083] The distance between these reference lines L51 and L52 was defined as the opening diameter (D) of the uneven portion of the metal substrate. The distance between the deepest point Pb2 of the recess and reference line L4 was defined as the depth (L) of the uneven portion of the metal substrate. From this result, the ratio D / D0 of the opening diameter (D) to the laser beam diameter (D0) was calculated. The measurement results for D, L, and D / D0 are shown in Table 3.

[0084] The metal-resin-metal bonded bodies were also evaluated for bonding strength in accordance with the above-mentioned evaluation of bonding strength (2). The evaluation results are shown in Table 3.

[0085] [Example 2] As shown in Table 2, the laser processing conditions were a scanning speed of 1000 mm / s, a theoretical printing time of 2.143 s, an actual printing time of 2.401 s, and a laser irradiation density of 0.22 J / mm 2 Two metal members (aluminum plates after laser treatment) were produced in the same manner as in Example 1, except for the above change, and a metal-resin-metal bonded body for evaluation was also produced. The joint cross section of the metal-resin-metal bonded body was evaluated. The results of cross-section observation by SEM are shown in Figure 8. The evaluation was performed in the same manner as in Example 1, and D and L were determined. The opening reference points were Pct1 for convex 1 and Pr2 for convex 2, which correspond to L32. The ratio D / D0 was calculated, and the measurement results of D, L, and D / D0 are shown in Table 3. The metal-resin-metal bonded bodies were also evaluated for bonding strength in accordance with the above-mentioned evaluation of bonding strength (2). The evaluation results are shown in Table 3.

[0086] [Example 3] Two rectangular aluminum plates measuring 5 mm thick, 25 mm wide, and 50 mm long were cut out from a hollow extrusion of A6063 aluminum alloy (A6063-T5) treated to the tempering code T5 specified in JIS H0001 to prepare the metal substrate. Other than that, the same procedures as in Example 1 were carried out to produce a metal-resin-metal bonded body for evaluation. The bonded cross section of the metal-resin-metal bonded body was evaluated. The results of observation of the cross section by SEM are shown in Figure 9. The evaluation was performed in the same manner as in Example 1, and D and L were determined. The opening reference points were set to point Pr1 corresponding to L31 for protrusion 1 and point Pr2 corresponding to L32 for protrusion 2. The ratio D / D0 was calculated, and the measurement results of D, L, and D / D0 are shown in Table 3. The metal-resin-metal bonded bodies were also evaluated for bonding strength in accordance with the above-mentioned evaluation of bonding strength (2). The evaluation results are shown in Table 3.

[0087] [Example 4] A rectangular aluminum plate measuring 1.5 mm thick, 18 mm wide, and 45 mm long was 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 to prepare the metal substrate.

[0088] Next, for the surface of this aluminum plate to be processed, the output was 42.5 J / s, the frequency was 60 kHz, the beam diameter was 60 μm, the irradiation interval was 90 μm, the scanning speed was 320 mm / s, the number of scans (irradiations) was 1, the theoretical printing time was 6.250 s, the actual printing time was 6.596 s, and the laser irradiation density was 0.24 J / mm 2 Laser treatment was performed by irradiating the laser under the conditions of (a) to form a bonding surface with the resin molded body. For the aluminum plate, the laser was irradiated to 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. The laser treatment conditions are shown in Table 2.

[0089] The metal members (aluminum plates after laser treatment) with the bonding surfaces formed as described above were inserted into molds fabricated in accordance with ISO 19095 using an injection molding machine (Nissei Plastic Industrial Co., Ltd., FNX1103-18A). Then, they were 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 body (metal-resin bonded body 12, FIG. 10 ) of aluminum plate (metal member 10) and resin molded body 9, with the resin molded body 9 having a rectangular shape measuring 3 mm thick, 10 mm wide, and 45 mm long, and the bonding area of the rectangular bonded portion between the aluminum plate (metal member 10) and resin molded body 9 being 5 mm x 10 mm.

[0090] The joint cross section of the metal-resin bonded body was evaluated. The results of observation of the cross section by SEM are shown in Fig. 11. The evaluation was performed in the same manner as in Example 1, and D and L were determined. The opening reference points were set to point Pr1 corresponding to L31 for protrusion 1 and point Pr2 corresponding to L32 for protrusion 2. The ratio D / D0 was calculated, and the measurement results of D, L, and D / D0 are shown in Table 3. The metal-resin bonded bodies were also evaluated for bonding strength in accordance with the above-mentioned evaluation of bonding strength (1). The evaluation results are shown in Table 3.

[0091] [Example 5] The laser processing conditions were: scanning speed 400 mm / s, theoretical printing time 5,000 s, actual printing time 5,335 s, laser irradiation density 0.23 J / mm 2 A metal member (aluminum plate material after laser treatment) and a metal-resin bonded body for evaluation were produced in the same manner as in Example 4, except that the resin composition was changed to polyphenylene sulfide (PPS) (manufactured by Polyplastics Co., Ltd., trade name: DURAFIDE, grade: 1150MF1) as the thermoplastic resin. The joint cross section of the metal-resin bonded body was evaluated. The results of observation of the cross section by SEM are shown in Fig. 12. The evaluation was performed in the same manner as in Example 1, and D and L were determined. The opening reference points were set to point Pr1 corresponding to L31 for protrusion 1 and point Pr2 corresponding to L32 for protrusion 2. The ratio D / D0 was calculated, and the measurement results of D, L, and D / D0 are shown in Table 3. The metal-resin bonded bodies were also evaluated for bonding strength in accordance with the above-mentioned evaluation of bonding strength (1). The evaluation results are shown in Table 3.

[0092] [Example 6] The metal was changed to rolled oxygen-free copper (C1020) as specified in JIS H3100. The laser processing conditions were changed to a scanning speed of 400 mm / s, a scanning count of 5, a theoretical printing time of 25,000 s, an actual printing time of 26,675 s, and a laser irradiation density of 0.23 J / mm. 2 A metal member (laser-treated copper plate material) and a metal-resin bonded body for evaluation were produced in the same manner as in Example 4, except that the temperature 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. The bonded cross section of the laser-treated metal member before joining the resin molded body was evaluated. The results of SEM observation of the cross section are shown in Figure 13. The evaluation was performed using the same method as in Example 1, and D and L were determined. The opening reference points were set to point Pr1 corresponding to L31 for convex 1 and point Pr2 corresponding to L32 for convex 2. Of the two convex portions and three concave portions used to calculate the opening diameter (D) and depth (L), only some of the convex portions and concave portions are shown in the cross-sectional photograph in Figure 13. The opening diameter (D) and depth (L) were calculated using the cross-sectional photograph showing the two convex portions and three concave portions. The ratio D / D0 was calculated, and the measurement results of D, L, and D / D0 are shown in Table 3. The metal-resin bonded bodies were also evaluated for bonding strength in accordance with the above-mentioned evaluation of bonding strength (1). The evaluation results are shown in Table 3.

[0093] [Example 7] The metal was changed to stainless steel plate material (SUS304), and the laser processing conditions were as follows: scanning speed 340 mm / s, number of scans 2, theoretical printing time 11.765 s, actual printing time 12.445 s, laser irradiation density 0.24 J / mm 2 A metal member (a laser-treated iron plate material) and a metal-resin bonded body for evaluation were produced in the same manner as in Example 4, except that the temperature 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 bonded cross section of the laser-treated metal member before bonding the resin molded article was evaluated. The results of observing the cross section using an SEM are shown in Figure 14. The evaluation was performed using the same method as in Example 1, and D and L were determined. The opening reference points for protrusion 1 were point Pr1 corresponding to L31, and for protrusion 2 were point Pr2 corresponding to L32. The ratio D / D0 was calculated, and the measurement results of D, L, and D / D0 are shown in Table 3. The metal-resin bonded bodies were also evaluated for bonding strength in accordance with the above-mentioned evaluation of bonding strength (1). The evaluation results are shown in Table 3.

[0094] [Example 8] As shown in Table 2, the laser processing conditions are output of 50 J / s, scanning speed of 300 mm / s, theoretical printing time of 7.143 s, actual printing time of 7.410 s, and laser irradiation density of 0.28 J / mm 2 Two metal members (aluminum plates after laser treatment) were produced in the same manner as in Example 1, except for the above change, and a metal-resin-metal bonded body for evaluation was also produced. The bonded cross section of the metal-resin-metal bonded body was evaluated. The results of cross-section observation by SEM are shown in Fig. 15. The evaluation was performed in the same manner as in Example 1, and D and L were determined. The opening reference points were Pct1 for convex 1 and Pr2 for convex 2, which correspond to L32. The ratio D / D0 was calculated, and the measurement results of D, L, and D / D0 are shown in Table 3. The metal-resin-metal bonded bodies were also evaluated for bonding strength in accordance with the above-mentioned evaluation of bonding strength (2). The evaluation results are shown in Table 3.

[0095] [Comparative Example 1] As shown in Table 2, the laser processing conditions were a scanning speed of 3000 mm / s, a theoretical printing time of 0.714 s, an actual printing time of 0.962 s, and a laser irradiation density of 0.19 J / mm 2 Two metal members (aluminum plates after laser treatment) were produced in the same manner as in Example 1, except for the above change, and a metal-resin-metal bonded body for evaluation was also produced. The joint cross section of the metal-resin-metal bonded body was evaluated. The results of cross-sectional observation using an SEM are shown in Figure 16. The evaluation was performed using the same method as in Example 1, and D and L were determined. In Comparative Example 1, when reference lines L1 and L2 were drawn, it was found that the intersections Pct1 and Pct2 of each convex portion with the surface of the molten metal layer were the same as the highest points Pt1 and Pt2 of each convex portion. Therefore, the opening reference points were Pt1 and Pt2. Furthermore, since the reference lines L51 and L52 used to determine the opening diameter (D) coincided with L1 and L2, the distance between L1 and L2 was determined to be the opening diameter (D) of the recess. The ratio D / D0 was calculated, and the measurement results of D, L, and D / D0 are shown in Table 3. The metal-resin-metal bonded bodies were also evaluated for bonding strength in accordance with the above-mentioned evaluation of bonding strength (2). The evaluation results are shown in Table 3.

[0096] Comparative Example 2 Two rectangular aluminum plates measuring 5 mm thick, 25 mm wide, and 50 mm long were cut out from a hollow extrusion of A6063 aluminum alloy (A6063-T5) treated to the tempering code T5 specified in JIS H0001 to prepare the metal substrate. As shown in Table 2, the laser processing conditions were a scanning speed of 3000 mm / s, a theoretical printing time of 0.714 s, an actual printing time of 0.962 s, and a laser irradiation density of 0.19 J / mm 2 Two metal members (aluminum plates after laser treatment) were produced in the same manner as in Example 1, except for the above change, and a metal-resin-metal bonded body for evaluation was also produced. The joint cross section of the metal-resin-metal bonded body was evaluated. The results of cross-sectional observation using an SEM are shown in Figure 17. The evaluation was performed using the same method as in Example 1, and D and L were determined. It was also found that in Comparative Example 2, when reference lines L1 and L2 were drawn, the intersections Pct1 and Pct2 of each convex portion with the surface of the molten metal layer were the same as the highest points Pt1 and Pt2 of each convex portion. Therefore, the opening reference points were Pt1 and Pt2. Furthermore, since the reference lines L51 and L52 used to determine the opening diameter (D) coincided with L1 and L2, the distance between L1 and L2 was determined to be the opening diameter (D) of the recess. The ratio D / D0 was calculated, and the measurement results of D, L, and D / D0 are shown in Table 3. The metal-resin-metal bonded bodies were also evaluated for bonding strength in accordance with the above-mentioned evaluation of bonding strength (2). The evaluation results are shown in Table 3.

[0097] Comparative Example 3 Two rectangular aluminum plates measuring 5 mm thick, 25 mm wide, and 50 mm long were cut out from a hollow extrusion of A6063 aluminum alloy (A6063-T5) treated to the tempering code T5 specified in JIS H0001 to prepare the metal substrate. In addition, as shown in Table 2, the laser processing conditions were: irradiation interval 130 μm, scanning speed 500 mm / s, theoretical printing time 2.308 s, actual printing time 2.487 s, laser irradiation density 0.23 J / mm2 Two metal members (aluminum plates after laser treatment) were produced in the same manner as in Example 1, except for the above change, and a metal-resin-metal bonded body for evaluation was also produced. The bonded cross section of the metal-resin-metal bonded body was evaluated. The results of observation of the cross section by SEM are shown in Figure 18. The evaluation was performed in the same manner as in Example 1, and D and L were determined. The opening reference points for protrusion 1 were point Pr1 corresponding to L31, and for protrusion 2 were point Pr2 corresponding to L32. The ratio D / D0 was calculated, and the measurement results of D, L, and D / D0 are shown in Table 3. In Comparative Example 3, as can be seen from FIG. 18, there was an area (unmelted layer area) that was not covered with the molten metal layer due to non-irradiation of the laser in the center of the surface of each convex portion. The metal-resin-metal bonded bodies were also evaluated for bonding strength in accordance with the above-mentioned evaluation of bonding strength (2). The evaluation results are shown in Table 3.

[0098] [Table 2]

[0099] [Table 3]

[0100] [Consider] According to the manufacturing methods of metal members of Examples 1 to 8, the predetermined laser irradiation density was satisfied, and cross-sectional observation by SEM revealed that a metal melt layer was formed over the entire surface of the metal substrate, forming an uneven portion. Furthermore, the opening diameter (D) of the recess was relatively small relative to the beam diameter D0, within a predetermined ratio range, and therefore the joining area between the metal member and the resin molded body at the joining surface was large and the depth (L) was small. Therefore, the resin penetrated into the uneven portion of the metal melt layer of the metal member and joined, and the anchor effect between the uneven portion and the resin was fully exerted, providing sufficient joining strength and preventing fracture at the joining interface, resulting in a high cohesive failure rate.

[0101] On the other hand, in Comparative Examples 1 and 2, the laser scanning speed was relatively high, so the laser irradiation density was lower than the predetermined range, and therefore, from cross-sectional observation by SEM, the opening diameter (D) of the uneven portion was relatively large, and it was also large relative to the beam diameter D0, and the depth (L) was small. Therefore, it is presumed that the fitting effect between the metal member and the resin molded body was reduced, resulting in more interfacial fractures.

[0102] The ratio (b) of the theoretical printing time to the actually measured printing time was 0.964 in Example 1, while it was 0.743 in Comparative Example 1. In Comparative Example 1, which had a faster scanning speed than Example 1, the time that the laser light output was ON was relatively shorter than the total time that the laser light output was ON and OFF, and it was confirmed that the laser irradiation density was reduced accordingly, and the bonding condition was deteriorated.

[0103] Furthermore, in Comparative Example 3, because the laser light irradiation interval was relatively large, cross-sectional observation by SEM confirmed that non-laser-irradiated areas (unmelted layer areas) remained between the recesses perforated by laser irradiation, which were not irradiated with the laser and were not covered with deposits generated by laser irradiation (for example, the area indicated by reference numeral 14 in Figure 18). That is, in Comparative Example 3, it was confirmed that non-laser-irradiated areas remained on the joining surface of the metal members, and that the metal molten layer was partially absent and partially formed. In the non-laser-irradiated areas, the surface of the metal member was covered with an oxide film. Furthermore, in Comparative Example 3, unevenness was not formed over the entire joining surface. For this reason, it is believed that in Comparative Example 3, the mechanical bond with the resin was weakened in the non-laser-irradiated areas, resulting in increased interfacial fracture at the joining area. [Explanation of symbols]

[0104] 1...Laser irradiation section, 2...Laser movement section, 3...Switching position (between irradiation and movement), 4...Metal substrate (workpiece), 5...Scanning direction, 6...Beam diameter, 7...Irradiation width, 8 (8')...Laser light trajectory, 9...Resin molded body, 10 (10')...Metal member, 11...Special jig for shear test, 12...Metal-resin bonded body, 13...Metal-resin-metal bonded body, 14...Laser unirradiated area (unmelted layer area)

Claims

1. A method for manufacturing a metal member, comprising: an irradiation step of irradiating a surface of a metal substrate made of metal with laser light to form a metal molten layer caused by melting and solidifying the metal substrate; and manufacturing a metal member having the metal molten layer formed on the surface of the metal substrate, In the irradiation step, a joining surface is formed on the surface of the metal base material, and the metal melting layer having an uneven portion is formed over the entire surface of the joining surface, In the irradiation step, the laser irradiation density of the laser light is 0.2 J / mm 2 1.9J / mm or more 2 or less, and the laser irradiation density (J / mm 2 ) of the laser light is expressed by the following formulas (A1) to (A3) using the theoretical total energy (J) of the laser light, the beam area (mm 2 ) of the laser light, the frequency (Hertz (Hz)) of the laser light, the theoretical printing time (s) of the laser light, and the actual printing time (s) of the laser light, The beam diameter (D ０ ) is 20 μm to 200 μm, The beam diameter (D ０ The ratio of the opening diameter (D) in the concave-convex portion to the opening diameter (D) (D / D ０ ) is 1.1 or less. Laser irradiation density = a × b (A1) a = theoretical total energy / (beam area × frequency × theoretical printing time) (A2) b = theoretical printing time / actual printing time (A3)

2. The method for manufacturing a metal member according to claim 1, characterized in that in the irradiation step, the laser irradiation density of the laser light is 0.22 J / mm 2 or more and 1.9 J / mm 2 or less.

3. The theoretical total energy is expressed by the product of the laser light output (J / s) and the theoretical printing time (s) using the following formula (A4): The method for manufacturing a metal member according to claim 1 or 2, characterized in that the theoretical printing time is expressed by the following formula (A5) using the set area (mm 2 ), the number of laser light scans (times), the laser light irradiation interval (mm), and the laser light scanning speed (mm / s). Theoretical total energy = (output x theoretical printing time) (A4) Theoretical printing time = (set area x number of irradiations) / (irradiation interval x scanning speed) (A5)

4. 4. The method for manufacturing a metal member according to claim 1, wherein the uneven portion has a structure in which at least one of adjacent protrusions protrudes toward a recess.

5. 5. The method for manufacturing a metal member according to claim 1, wherein the scanning speed of the laser light is 200 mm / s to 2000 mm / s.

6. 6. The method for manufacturing a metal member according to claim 1, wherein the metal is aluminum, copper, iron, or an alloy containing any of these metals.

7. a resin molding step of forming a resin molded body on the surface of the metal member obtained by the manufacturing method according to any one of claims 1 to 6, A method for producing a metal-resin joined body in which the metal base material and the resin molded body are joined via the metal fusing layer, comprising: In the resin molding step, the metal member and the resin molded body are joined together in a state where the resin fills the uneven portions at the joining surfaces.

8. 8. The method for producing a metal resin bonded body according to claim 7, wherein the resin molded body contains a thermoplastic resin or a thermosetting resin.

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