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 and can secure sufficient airtightness.SOLUTION: There are provided a method for manufacturing a metal member which includes an irradiation step of forming a marking pattern having a continuous uneven part along an irradiation locus of a laser beam thereon by irradiation of the surface of a metal member with a laser beam, and manufactures a metal member where a plurality of marking patterns are formed on the surface of the metal member, wherein the plurality of marking patterns are formed of one continuous straight line or curve so that a start point and an end point of the irradiation with the laser beam coincide with each other, do not cross each other, and adjacently run in parallel with each other by irradiation of the adjacent parts with a laser beam in the irradiation step, a beam diameter D of the laser beam is 20-200 μm, an irradiation interval P of the laser beam is 20-200 μm, and a ratio (P / D) of P to D is 1.1 or more and 2 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 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 that, in manufacturing a composite molded body consisting of a metal molded body and a resin molded body, a laser scanning process is performed to form markings consisting of straight lines and / or curves in one or two different directions on the joining surface of the metal molded body, and the resin molded body is insert-molded onto the joining surface on which the markings are formed, ensuring that the markings do not intersect with each other, thereby enhancing the joining strength in the desired direction. Patent Document 6 also discloses laser processing conditions for forming a joint between the metal surface and the resin by performing a laser scanning process on the metal surface in one scanning direction and a laser scanning process 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] Patent No. 6055529 [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, Patent Document 5, as mentioned above, is a method for increasing bonding strength in a desired direction, but does not take into consideration ensuring airtightness. Furthermore, Patent Document 6 requires laser scanning in two intersecting directions, which leaves room for improvement in terms of the excessively long processing time. 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 article that has high bonding strength and can ensure sufficient airtightness, 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] An irradiation step of irradiating a surface of a metal substrate made of metal with laser light to form a marking pattern having continuous concave and convex portions along the irradiation locus of the laser light on the surface of the metal substrate, A method for manufacturing a metal member in which a plurality of the marking patterns are formed on a surface of the metal substrate, comprising: the marking pattern is made up of a single continuous straight line or curve so that the start point and end point of the irradiation of the laser light coincide with each other and do not intersect; In the irradiation step, the energy density (J / mm ) is calculated from the laser light output W (W), the number of scans N (times), the irradiation interval P (mm), and the scanning speed V (mm / s) by the formula (A2). 2 ) and calculate the energy density of 0.5 J / mm when performing laser processing on the metal substrate containing aluminum as the main metal. 2 More than 5J / mm 2 The laser processing conditions for forming the marking pattern are set so as to achieve the following: When laser processing is performed on the metal substrate containing iron as the main metal, the energy density is 0.5 J / mm2 More than 10J / mm 2 The laser processing conditions for forming the marking pattern are set so as to achieve the following: When laser processing is performed on the metal substrate containing copper as the main metal, the energy density is 0.5 J / mm 2 More than 20J / mm 2 Setting laser processing conditions to form the marking pattern so as to achieve the following: Energy density = (W × N) / (P × V) Equation (A2) In the irradiation step, the laser light is irradiated under the set laser processing conditions, A method for manufacturing a metal member, characterized in that in the irradiation step, a plurality of the marking patterns running parallel to each other are formed by irradiating adjacent portions with the laser light, the beam diameter D of the laser light is 20 μm to 200 μm, the irradiation interval P of the laser light is 20 μm to 200 μm, and the ratio (P / D) of the irradiation interval P to the beam diameter D is 1.1 or more and 2 or less. [2] The surface of the metal substrate is formed with the uneven portion, which is composed of recesses formed by the metal at the location irradiated with the laser light diffusing outward from the irradiation center of the laser light, and protrusions formed by the metal diffusing from the recesses and accumulating around the recesses, The method for manufacturing a metal member described in [1] is characterized in that, on the surface of the metal member, in the area sandwiched between adjacent marking patterns, the convex portions included in the adjacent marking patterns are formed so as to come into contact with each other and become integrated, and no untreated area is formed in which the metal base material is exposed before being irradiated with the laser light. [3] The metal substrate has a hollow shape having a hollow portion therein and an open end portion surrounding the hollow portion; The method for manufacturing a metal member according to [1] or [2], wherein in the irradiating step, laser light is irradiated so that the marking pattern is formed on the opening edge. [4] The method for manufacturing a metal component according to [3], characterized in that the laser light is irradiated at the opening end so as not to form a marking pattern that connects both sides of the marking pattern. [5] The method for manufacturing a metal component according to any one of [1] to [4], characterized in that the laser light is irradiated so that the arithmetic mean roughness Ra of the surface of the metal component obtained through the irradiation step is 24 μm to 200 μm. [6] The method for producing a metal member according to any one of [1] to [5], 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 [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, comprising the steps of: The resin composition shape In the step, the metal member and the resin molded body are joined together in a state in which the resin has penetrated into the uneven portions of the marking pattern. [8] The resin composition shape [7] The method for producing a metal resin bonded body according to [7], wherein in the step, a resin composition containing a thermoplastic resin or a thermosetting resin is molded onto the metal member. [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 molded body that has excellent bonding strength between the metal member and the resin molded body and can ensure sufficient airtightness. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing an example of a marking pattern. [Figure 2] 2A is a schematic diagram showing a metal member having a hollow portion and an open end, and FIG. 2B is a schematic diagram showing a metal-resin bonded body using the metal member. The upper figures are top views of the metal member. The lower figures are cross-sectional views of the upper figures taken along lines AA and BB. [Figure 3] FIG. 3 is a schematic diagram showing a case where intersecting marking patterns exist in FIG. [Figure 4] FIG. 4 is a schematic diagram showing the relationship between the beam diameter of the laser light and the irradiation interval. [Figure 5] FIG. 5 is a schematic diagram showing an example of how to determine the opening diameter (T) and depth (L) in the concave-convex portion. [Figure 6] FIG. 6 is a diagram for explaining an outline of the bonding strength evaluation (1) (shear test). [Figure 7] FIG. 7 is a diagram for explaining an outline of the bonding strength evaluation (2) (shear test). [Figure 8] FIG. 8 is a diagram for explaining an outline of the evaluation of the airtightness of a metal-resin bonded body. [Figure 9] FIG. 9 is a diagram for explaining an outline of the evaluation of the airtightness of a metal-resin-metal bonded body. [Figure 10] FIG. 10 is a diagram showing an outline of the metal-resin bonded body for the evaluation of airtightness. [Figure 11] FIG. 11 is a diagram showing an outline of a metal-resin-metal bonded body for evaluation of airtightness according to Example 8. As shown in FIG. [Figure 12] FIG. 12 is a diagram showing an outline of a metal-resin bonded body for evaluation of bonding strength. [Figure 13] FIG. 13 is a diagram (photograph) of a cross section of the metal-resin bonded body produced in Experimental Example 1, observed with an SEM. [Figure 14] FIG. 14 is a diagram (photograph) of a cross section of the metal-resin bonded body produced in Experimental Example 4, observed with an SEM. [Figure 15] FIG. 15 is a diagram (photograph) of a cross section of the metal-resin bonded body produced in Experimental Example 7, observed with an SEM. [Figure 16] FIG. 16 is a diagram showing an outline of a metal-resin-metal bonded body for evaluation of bonding strength according to Experimental Example 8. As shown in FIG. [Figure 17] FIG. 17 is a diagram (photograph) of a cross section of the resin bonding surface side of the metal member produced in Experimental Example 9 before resin bonding, observed with an SEM. [Figure 18]FIG. 18 is a diagram (photograph) of a cross section of the resin bonding surface side of the metal member produced in Experimental Example 11 before resin bonding, observed with an SEM. [Figure 19] FIG. 19 is a diagram (photograph) of a cross section of the metal-resin bonded body produced in Comparative Experimental Example 1, observed with an SEM. [Figure 20] FIG. 20 is a diagram (photograph) of a cross section of the metal-resin bonded body produced in Comparative Experimental Example 4, 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 the surface of a metal substrate made of metal with laser light to form a plurality of marking patterns (hereinafter, sometimes simply referred to as "marking patterns") having continuous uneven portions along the irradiation path of the laser light on the surface of the metal substrate. This produces a metal member having the marking patterns formed on the surface of the metal substrate. The method for producing a metal-resin bonded body of the present invention also includes a resin molding step of bonding 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 a pretreatment such as blasting, degreasing, etching, desmutting, chemical polishing, or electrolytic polishing as a 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"). By the laser treatment, multiple marking patterns having continuous concave and convex portions are formed on the surface of the metal substrate along the irradiation path of the laser light, thereby obtaining the metal member according to the present invention. While 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, because this is advantageous for spot-processing the metal substrate as in the present invention.

[0017] In the present invention, a plurality of the marking patterns are formed on the surface of a metal substrate to form a bonding surface for bonding with an object to be bonded. The bonding surface may be formed on only a portion of one surface of the metal substrate, the entire surface, or a portion or entire surface of both surfaces, as long as the bonding surface is formed in a 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 intended 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 a "bonded portion" to distinguish it from the above.

[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 marking pattern) The marking pattern is continuously formed on the surface of the metal substrate along the laser beam irradiation path. The principle of marking pattern formation in the irradiation process is roughly as follows. When a metal substrate is irradiated with a laser, the energy from the laser irradiation melts, diffuses, and vaporizes the metal substrate. The metal diffuses and vaporizes from the center of the irradiation outward, creating holes, which form the bases of recesses. The unirradiated areas on both sides of the recesses (neighboring areas) form the bases of protrusions. At the same time, the molten metal is partially or completely oxidized to form metal oxides, which diffuse, deposit, and solidify around the irradiated areas that will become recesses, forming protrusions. In the areas sandwiched between the marking patterns, the protrusions are preferably formed so that the protrusions of adjacent marking patterns come into contact with each other and are integrated. It is preferable that the surface of the metal component does not have exposed areas (untreated areas) of the metal substrate, which correspond to the unirradiated areas described below. The metal oxide deposits form a film-like coating that covers the recesses and protrusions. In this way, a metal fusion layer that forms the uneven shape of the uneven portion is formed by the deposit made of metal oxide formed on the surface of the metal substrate. In other words, the marking pattern is formed by the continuous existence of a deposit (metal fusion layer) made of metal oxide having such uneven portion (uneven shape) along the irradiation locus of the laser light. When the laser irradiation is performed adjacent to each other, a repeating structure in which the concave and convex portions are adjacent to each other is formed.

[0020] In addition, as a method for confirming the formation state of such a metal fusion layer in the marking pattern, for example, the metal fusion layer can be dissolved by alkali etching treatment, and then it can be confirmed by distinguishing it from the metal substrate that does not dissolve. In addition, 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. A hydroxyl-containing film containing hydroxyl groups is formed on the outermost layer of the metal fusing layer in the marking pattern.

[0021] As described above, when a metal member has a laser-unirradiated portion (untreated portion) that has not been irradiated with a laser, the laser-unirradiated portion does not have a marking pattern, nor does it have a metal melt layer that forms the uneven portion. Typically, an oxide film is formed in the laser-unirradiated portion. Since the laser-unirradiated portion does not have uneven portions and is usually flat, bonding a resin or the like to that portion cannot be expected to improve the bonding strength due to the mechanical bonding caused by the uneven portion. Furthermore, since the flatness is prone to the formation of voids, improvement in airtightness cannot be expected. Therefore, if a laser-unirradiated portion remains on the bonding surface and a marking pattern is not formed over the entire bonding surface, the metal melt layer that forms the uneven portion is not present, which reduces the bonding strength of the metal-resin bonded body and may result in fracture at the bonding interface. Therefore, in the present invention, it is preferable that a marking pattern is formed over the entire bonding surface of the metal member. Furthermore, since the hydroxyl-containing film described above is not present in the laser-unirradiated portion, interaction due to chemical bonding caused by hydroxyl groups cannot be expected.

[0022] As described above, the marking pattern 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. Such recesses and protrusions can be confirmed by observing the surface or cross section of the metal member, for example, using a scanning electron microscope (SEM). The structure of the recesses and protrusions will be described later.

[0023] Furthermore, in the present invention, each marking pattern must consist of a single continuous straight or curved line so that the start and end points of laser light irradiation coincide, and the lines must not intersect. If the start and end points of laser light irradiation do not coincide, there will inevitably be areas not surrounded by the marking pattern (open areas), and since these areas do not have the concave-convex portions or molten metal layer of the marking pattern, it is not possible to expect the interlocking effect of the concave-convex portions to be realized. Therefore, there is a risk that such open areas will impair the airtightness between the interior (inside) and exterior (outside) surrounded by the marking pattern.

[0024] Furthermore, when laser beam irradiation is performed in an intersecting manner, resulting in an intersecting marking pattern, the uneven portions formed by the first laser beam irradiation are melted and vaporized again by the energy of the second intersecting laser beam irradiation, forming perforations at the intersecting portions, resulting in the molten metal being deposited as metal oxide. In this case, when metal oxide deposits around the recesses created by the second intersecting laser beam irradiation, it also deposits in the recesses created by the first laser beam irradiation, resulting in the metal oxide being deposited in a sparser state, more likely to contain voids inside than in the first laser beam irradiation. Bonding a resin or other material to a portion containing many voids could impair airtightness.

[0025] Examples of when the start and end points of laser light irradiation coincide / do not coincide, and when they intersect / do not intersect, are shown in Figure 1. That is, when the marking pattern is O-shaped as in (a), square-shaped as in (b), or eight-shaped as in (d), the start and end points coincide (symbol 1). In these marking patterns, the inside and outside enclosed by the marking pattern are separated. On the other hand, when the marking pattern is U-shaped as in (c) or α-shaped as in (e), the start point (symbol 2) and end point (symbol 3) do not coincide, so the inside and outside enclosed by the marking pattern are not separated, or there are parts that are not separated. Furthermore, when the marking pattern is O-shaped as in (a), square-shaped as in (b), or U-shaped as in (c), there are no intersecting parts. On the other hand, when the marking pattern is eight-shaped as in (d) or α-shaped as in (e), there are intersecting parts.

[0026] Therefore, it is preferable to irradiate the laser light so that the marking pattern is O-shaped as shown in (a), square-shaped as shown in (b), or similar shapes (triangle, polygon, ellipse, semicircle, fan-shape, star-shape, etc.). With such a shape, the start and end points of the laser light irradiation coincide, separating the interior and exterior surrounded by the marking pattern, and since they do not intersect, sparse metal oxide deposition is unlikely to occur. Therefore, when resin or the like is bonded via these marking patterns, sufficient airtightness is maintained. Note that the multiple marking patterns may have the same shape or different shapes. From the viewpoint of reducing the area of the region sandwiched between the marking patterns and increasing the density of the marking patterns, it is preferable that the multiple marking patterns have the same shape.

[0027] To form marking patterns of the preferred shape described above in parallel, for example, a first laser irradiation is followed by a second or subsequent laser irradiation, which are concentric with the first laser irradiation but are different in size and do not intersect with each other. This allows multiple marking patterns to be formed adjacently (parallel). Alternatively, a first laser irradiation may be followed by a second or subsequent laser irradiation, which are eccentric with the first laser irradiation but are different in size and do not intersect with each other. Conversely, even if the marking patterns are O-shaped or square-shaped, if multiple marking patterns are formed by arranging them in a circular array or the like rather than parallel to each other, there will be a portion (open portion) between adjacent marking patterns that is not surrounded by the marking patterns, and the airtightness of the interior surrounded by the multiple marking patterns will not be maintained.

[0028] Forming a marking pattern such that the start and end points of laser light irradiation coincide and do not intersect is particularly suitable when using a metal substrate (metal member) having a shape such as that shown in FIG. 2. That is, FIG. 2 is a schematic diagram showing a metal member 6(a) after forming a marking pattern and a metal-resin bonded body 8(b) in which a resin molded body 7 is bonded to the metal member 6. The white arrow in the center indicates the change from (a) to (b). The upper diagram in (a) is a top view of the metal member 6 as seen from above, and the lower diagram in (a) is a schematic cross-sectional view of the AA section of the top view. As can be seen from these figures, the metal member 6 has a bottom surface and a wall surface rising upward from the periphery of the bottom surface, with an open end at the upper end surface of the wall surface. The metal member 6 is a hollow-shaped member with a bottom, having a hollow portion 4 inside (inside) surrounded by the bottom surface and the wall surface, and an open end 5 surrounding the periphery of the hollow portion. Note that a metal substrate (metal member) having such a shape may not have a bottom surface (in this case, it has a hollow portion 4 and an open end portion 5 including a wall surface portion). Furthermore, as long as it has a hollow portion 4 and an open end portion 5 surrounding it, it may have a cylindrical shape (such as a rectangular pillar or a columnar shape), a doughnut shape, a washer shape, or the like. On the other hand, as shown in (b), a resin molded body 7 is bonded to cover the surface of this open end portion 5, sealing the hollow portion 4. In the upper view of (b), a resin molded body 7 is bonded to cover the open end portion 5. The lower view of (b) is a schematic cross-sectional view of the B-B cross section of the upper view.

[0029] In the case of a metal substrate 6 having such a narrow opening edge 5, when an object to be joined (such as a resin molded body, reference numeral 7) is joined to the opening edge 5, the area of the joint is limited, and the airtightness between the interior (inside) and the outside is easily compromised. For this reason, it is preferable to form the predetermined marking pattern 9 so that the start and end points of the laser light irradiation coincide, so as to surround the surface of the opening edge 5, and to form (run parallel to) multiple marking patterns 9 in a concentric pattern, etc. After that, the resin molded body 7 is joined.

[0030] In this case, it is preferable not to form a marking pattern that impairs the airtightness between the interior (inside) and the outside, sandwiched between the opening end 5 on which the marking pattern 9 is formed. For example, as shown in Fig. 3, it is preferable not to irradiate laser light that forms a marking pattern 10 that intersects with the marking pattern 9. Since such a marking pattern 10 intersects with the marking pattern 9, it not only causes the deposition of metal oxide in a sparse state including voids as described above, but also may cause communication between both sides (inside and outside) on either side of the opening end 5 on which the marking pattern 9 is formed, impairing the airtightness (creating a leak path).

[0031] (Laser treatment conditions) In the irradiation step, the laser processing conditions for forming a marking pattern having predetermined concave and convex portions are set as follows. First, in the present invention, the formation of the aforementioned laser-unirradiated (untreated) portions in the concave-convex portions of the marking pattern is prevented. To achieve this, laser light is irradiated so that the ratio (P / D) of the irradiation interval P to the laser beam diameter D is 1.1 or more and 2 or less. By setting the P / D at or above the lower limit, it is possible to prevent excessive accumulation of metals mutually diffused from adjacent (parallel) marking patterns due to laser light irradiation, which would otherwise cause voids (sparse portions) to form between the deposits, thereby improving the bonding strength and airtightness between the metal member and the object to be joined. Furthermore, by setting the P / D at or below the upper limit, laser light irradiation does not result in the formation of laser-unirradiated (untreated) portions without concave-convex portions on the surface of the metal substrate between adjacent (parallel) marking patterns, thereby improving the bonding strength and airtightness between the metal member and the object to be joined. The lower limit of the P / D is preferably 1.2, more preferably 1.3, and even more preferably 1.5. The upper limit of the P / D is preferably 1.9, more preferably 1.8, and even more preferably 1.6.

[0032] The relationship between the beam diameter and the irradiation interval of the laser beam can be explained with reference to FIG. 4. The irradiation interval P of the laser beam refers to the distance between the trajectory 14 of one laser beam irradiated on the target object and the trajectory 14' of another laser beam irradiated adjacent to the laser. More specifically, the irradiation interval P of the laser beam refers to the distance between either end of the trajectory of the one laser beam in a direction perpendicular to the scanning direction 11 and the end of the trajectory of the other laser beam on the same side as the one laser beam. When a pulsed laser is irradiated, the trajectory of the laser beam is represented by a continuous trajectory of pores formed by individual laser pulses. In this case, the irradiation interval P of the laser beam is represented by the symbol 13 and 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 beam diameter D (symbol 12) of the laser beam.

[0033] The beam diameter D of the laser light is set to 20 μm to 200 μm. By setting the beam diameter D to 20 μm or more, it is possible to prevent the unevenness formed from becoming excessively fine, and also to shorten the laser processing time relative to the bonding area. By setting the beam diameter D to 200 μm or less, it is possible to prevent the unevenness formed from becoming excessively large, and also to prevent the laser irradiation density from becoming excessively small. The lower limit of the beam diameter D is preferably 30 μm, more preferably 40 μm, and even more preferably 50 μm. The upper limit of the beam diameter D is preferably 180 μm, more preferably 150 μm, and even more preferably 100 μm.

[0034] The laser beam irradiation interval P is set to 20 μm to 200 μm. By setting the irradiation interval P to 20 μm or more, it is possible to prevent adjacent (parallel) marking patterns from being too close to each other and to shorten the laser processing time for the bonding area. By setting the irradiation interval P to 200 μm or less, it is possible to prevent adjacent (parallel) marking patterns from being too far apart. The preferred lower limit of the irradiation interval P is 30 μm, more preferably 40 μm, even more preferably 50 μm, and particularly preferably 60 μm. The preferred upper limit of the irradiation interval P is 180 μm, more preferably 150 μm, even more preferably 120 μm, and particularly preferably 100 μm.

[0035] Furthermore, the number of laser beams irradiated per unit length is preferably 5 to 50 per mm. By setting the number of irradiation beams at or above the lower limit, it is possible to prevent adjacent (parallel) marking patterns from being too close to each other and to shorten the laser processing time per bonding area. By setting the number of irradiation beams at or below the upper limit, it is possible to prevent adjacent (parallel) marking patterns from being too far apart. A more preferred lower limit for the number of irradiation beams is 5.5 per mm, an even more preferred lower limit is 6 per mm, an especially preferred lower limit is 8 per mm, and an even more especially preferred lower limit is 10 per mm. A more preferred upper limit for the number of irradiation beams is 35 per mm, an even more preferred upper limit is 25 per mm, an especially preferred upper limit is 20 per mm, and an even more especially preferred upper limit is 17 per mm.

[0036] 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 P (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 / P) × Width × N) / V) × W) / (Length × Width) Equation (A1) By modifying equation (A1), the following equation (A2) is obtained: Energy density can be calculated using equation (A2). Energy density = (W × N) / (P × V) Equation (A2)

[0037] The energy density is preferably 0.5 J / mm 2 That's all. As the energy density increases, the recesses in the uneven portions of the marking pattern formed on the surface of the metal substrate tend to become deeper, and the surface roughness (arithmetic mean roughness Ra) of the metal component after laser processing tends to increase. Note that the higher the melting point and the greater the thermal diffusion of the metal constituting the metal substrate, the less susceptible the metal substrate 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.

[0038] 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 3J / mm 2 Less than or equal to 2.5 J / mm 2 Below 2 J / mm, particularly preferably 2 The following is the result.

[0039] 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 Below 4 J / mm, particularly preferably 2 The following is the result.

[0040] 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 More than 8 J / mm 2 In addition, when performing laser treatment 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.

[0041] When the energy density is equal to or greater than the lower limit, the depth (L) of the recesses of the concave-convex portions in the marking pattern formed on the surface of the metal substrate tends to increase, and the aspect ratio (L / T) of the recesses to the opening diameter (T) tends to increase. Therefore, when the resin molded body penetrates into the concave-convex portions, a mechanical bond (anchor effect) between the concave-convex portions 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, it is easy to prevent the depth (L) of the recesses of the concave-convex portions formed on the surface of the metal substrate from becoming excessively large, and the aspect ratio (L / T) of the recesses to the opening diameter (T) of the recesses from becoming excessively large. Therefore, the resin molded body can penetrate deep into the concaves of the concave-convex portions, and effective bonding with the metal member is exerted throughout the concave-convex portions, which tends to improve airtightness. In addition, the structure of the convex portions of the concave-convex portions can be prevented from becoming elongated and pointed, which can suppress a decrease in mechanical strength due to the convex portions breaking, etc. In addition, it is possible to prevent the metal member from being broken when the metal-resin bonded body is fractured.

[0042] The laser conditions (laser processing conditions) in the laser processing may be appropriately set so as to achieve the above-mentioned energy density. Parameters of the laser processing conditions include the output power (W) of the laser light, the frequency (kHz) of the laser light, the beam diameter D (μm), the irradiation interval P (μm), the scanning speed (mm / s) of the laser light, and the number of scans (times) of the laser light. The number of scans refers to the number of times the laser light is repeatedly irradiated along the same irradiation path to form one marking pattern. 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.

[0043] [Table 1]

[0044] (Uneven part) The uneven portion formed in the marking pattern is a structure having uneven shapes on the order of μm. The uneven portion preferably has an arithmetic mean roughness Ra of 24 μm to 200 μm on the surface of the metal member after the marking pattern is formed. By setting Ra to 24 μm or more, sufficient unevenness is formed on the surface without excessive smoothness, which facilitates the resin penetration and the interlocking effect, thereby improving the bonding strength and airtightness. Furthermore, by setting Ra to 200 μm or less, the structure of the protrusions of the uneven portion can be prevented from becoming excessively elongated and pointed, thereby suppressing a decrease in mechanical strength due to, for example, the breakage of the protrusions. Furthermore, it is possible to prevent fracture of the metal member when the metal-resin bonded body is broken. The lower limit of Ra is more preferably 27 μm, even more preferably 30 μm, and particularly preferably 35 μm. The upper limit of Ra is more preferably 150 μm, even more preferably 100 μm, and particularly preferably 50 μm.

[0045] Moreover, it is preferable that the uneven portion has a predetermined opening diameter (T) and depth (L) determined by the procedure shown in FIG.

[0046] To calculate the opening diameter (T) and depth (L) of the irregularities, 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 irregularities formed by laser irradiation, in which at least 12 recesses and 11 protrusions are alternately arranged in succession. The opening diameter (T) and depth (L) can then be calculated from the irregularities included in this cross-sectional image.

[0047] Specifically, as shown in Fig. 5, this is determined by drawing the following lines on the cross-sectional photograph. Fig. 5 is an example of a schematic representation of a cross-sectional photograph that can be used to calculate the opening diameter (T) and depth (L) of the concave-convex portion. Fig. 5 assumes the use of a metal-resin bonded body in which a resin molded body 7 is bonded to a metal member 6 on which a concave-convex portion has been formed after the marking pattern has been formed.

[0048] First, in FIG. 5, for 12 arbitrarily selected consecutive recesses, the deepest of the bottoms of each recess is designated as the minimum recess Pb1. 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 bottoms of each recess is smallest. Next, the highest convexity among the convexities sandwiched between the 12 recesses is designated as the highest convexity Pt1. A reference line RL2 is drawn that passes through the highest convexity 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 highest convexity Pt1, respectively, it is possible to prevent the depth L from being calculated as being excessively larger or smaller than the actual value, thereby preventing the aspect ratio (L / T) from being calculated as being excessively larger or smaller than the actual value. Next, 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 5) in order.

[0049] For the above-mentioned lines a to l, parallel median lines are drawn midway between adjacent lines, and these median lines are designated lines A to K, respectively. The distance between lines A and B is taken as the opening diameter T1 of the recess sandwiched between lines A and B and through which line b passes. Similarly, the distances between adjacent lines A to K are taken as opening diameters T1 to T10. Furthermore, for each of lines b to k, the distance from the bottom of each recess to reference line RL2 is taken as the depths L1 to L10 of the ten recesses. The opening diameters T1 to T10 and depths L1 to L10 correspond to the opening diameters T and depths L, respectively, of the ten recesses through which lines b to k pass, excluding the lines a and l at both ends.

[0050] In this way, the depths L1 to L10 and opening diameters T1 to T10 can be obtained for the 10 recesses through which lines b to k in Figure 5 pass. Furthermore, the Smirnoff-Grubbs test is used to detect outliers among the depths L1 to L10 and opening diameters T1 to T10. 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 T1 to T10. Furthermore, for the 10 recesses through which lines b to k included in Fig. 5 pass, recesses for which outliers were detected in either or both of the depth L and the opening diameter T are excluded, and the average depth L and the average opening diameter T of the remaining recesses are calculated from the depth L and the opening diameter T. The average depth L and the average opening diameter T thus obtained are defined as the depth (L) and the opening diameter (T) of the metal member or the metal-resin bonded body.

[0051] Furthermore, for the 10 recesses through which lines b to k in FIG. 5 pass, recesses for which outliers were detected in either or both of the depth L and the opening diameter T are excluded, and the depth L of each recess is divided by the opening diameter T of each recess to calculate the aspect ratio (L / T) of each recess. Then, an average value of the aspect ratios (L / T) of the multiple recesses is calculated from the aspect ratio (L / T) of each recess. The average value of the aspect ratios (L / T) thus obtained is defined as the aspect ratio (L / T) of the metal member or the metal-resin bonded body.

[0052] The opening diameter (T) 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 (T) 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 (T) 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.

[0053] 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 (T) 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.

[0054] Furthermore, the aspect ratio (L / T) of the opening diameter (T) to the depth (L) is usually 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 recesses and the resin, thereby sealing the entire surface. In this way, the recesses are shaped to fully engage the metal member and the resin via the recesses and convexoconcave portions in the marking pattern, thereby enhancing the bonding strength and airtightness between the metal member and the resin molded article. By making L / T greater than the above 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 enable the metal member and the resin to fully engage 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.

[0055] (Hydroxy group-containing film) It is desirable that a hydroxyl group-containing film containing hydroxyl groups be present on the outermost surface of the metal fusion layer in the marking pattern formed by irradiation with laser light.

[0056] 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).

[0057] 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.

[0058] 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 and airtightness 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 metal substrates subjected to laser treatment, metal substrates subjected to wet treatments such as hydrated oxide treatment with warm or hot water, chemical conversion treatment, and zincate treatment tend to have a higher hydroxyl group abundance. 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.

[0059] (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).

[0060] 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.

[0061] [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.

[0062] <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.

[0063] 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.

[0064] 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.

[0065] <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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] <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.

[0072] 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.

[0073] 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.

[0074] [3. Action and Effects] It has been known that, in order to increase the bonding strength of a metal-resin bonded body, it is effective to form uneven portions with a predetermined opening diameter and depth when treating a metal material with laser light, thereby forming a structure that is likely to cause mechanical interaction when the resin penetrates. In addition, it has been known that the molten portion of the metal substrate formed by the laser treatment is an oxygen-containing film that contains oxygen, and that this oxygen-containing film contributes to the development of bonding strength.

[0075] As a result of detailed investigations, the inventors have found that in order to improve the bonding strength and airtightness of a metal-resin molded body, it is necessary to provide a predetermined irradiation process for forming a plurality of predetermined marking patterns on the metal member, and to manufacture the metal member and the resin molded body so that they are bonded via the predetermined marking patterns on the bonding surfaces. Specifically, the marking pattern has continuous uneven portions along the irradiation locus of the laser light, and also has one continuous straight line so that the start point and end point of the irradiation of the laser light coincide with each other. line In the irradiation step, the laser beam is irradiated onto adjacent portions to form a plurality of the marking patterns that run parallel to each other, and the beam diameter D of the laser beam is 20 μm to 200 μm, the irradiation interval P of the laser beam is 20 μm to 200 μm, and the ratio of the irradiation interval P to the beam diameter D (P / D) is 1.1 or more and 2 or less.

[0076] This manufacturing method achieves a fitting effect in which the resin penetrates into the concave and convex portions of the marking pattern formed on the metal member and joins them together. Furthermore, the closed marking pattern enhances airtightness between the interior (inside) and exterior (outside) of the marking pattern. Furthermore, the non-intersecting marking patterns prevent voids from forming in the concave and convex portions at the intersections, enhancing airtightness. Furthermore, by specifying the laser beam diameter D, the irradiation interval P, and their ratio P / D, the distance between adjacent (parallel) marking patterns can be optimized during laser irradiation, thereby preventing excessive accumulation of interdiffused metals and the formation of voids (sparse portions) between deposits. Furthermore, the formation of unirradiated portions (untreated portions) without concave and convex portions on the surface of the metal substrate between the marking patterns can be prevented. Furthermore, the resulting concave and convex portions can be prevented from becoming excessively fine or large.

[0077] Therefore, in the present invention, a metal-resin bonded body having high bonding strength and capable of ensuring sufficient airtightness can be obtained.

[0078] Furthermore, in the present invention, the surface of the metal substrate is formed with an uneven portion consisting of recesses formed by the metal at the location irradiated with the laser light diffusing outward from the irradiation center of the laser light and protrusions formed by the metal diffusing from the recesses and accumulating around the recesses, and in the area on the surface of the metal substrate sandwiched between adjacent marking patterns, the protrusions included in the adjacent marking patterns are formed so as to come into contact with each other and become integrated, and no untreated area is formed in which the metal substrate before the irradiation with the laser light is exposed. Therefore, the fitting effect due to the penetration of resin or the like, which is the object to be joined, is easily achieved.

[0079] Furthermore, the present invention is particularly useful when using a metal substrate having a hollow shape with an internal hollow portion and an open end surrounding the hollow portion. That is, by irradiating the metal substrate with laser light so that the marking pattern is formed at the open end, and then joining the resin molded body, which is the object to be joined, so as to cover the open end and the hollow portion, it is possible to maintain airtightness between the interior (hollow portion) and the outside of the metal substrate. In this case, it is preferable to irradiate the metal substrate with laser light so as not to form a marking pattern that connects both sides of the marking pattern, in order to avoid impairing the airtightness.

[0080] Furthermore, in the present invention, the arithmetic mean roughness Ra of the surface of the metal member obtained through the irradiation step by the above-mentioned method is 24 μm to 200 μm, which makes it easier for the target object, such as resin, to penetrate and achieve a fitting effect. [Example]

[0081] Preferred embodiments of the present invention will be specifically described below based on examples, comparative examples, experimental examples, and comparative experimental examples, but the present invention should not be construed as being limited thereto.

[0082] [Evaluation method] <Evaluation of joint cross section> The metal member or metal-resin bonded body before being bonded to the resin molded body was cut in the thickness direction, embedded in epoxy resin, and then wet-polished to prepare a sample for evaluation of the bonded cross section. The thickness direction cross section of the sample for evaluation of the bonded cross section was observed using a scanning electron microscope (JEOL, JSM-7200F) at a magnification of 100 to 500 times. From the results of the SEM observation of the cross section, the length of the approximately planar region sandwiched between the convex portions of adjacent marking patterns and where the metal base material was exposed before laser light irradiation, and the length of the unirradiated portion were measured. The measurement results are shown in Table 5.

[0083] <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 6, a metal-resin bonded body 8, consisting of a metal member 6 and a resin molded body 7, was fixed to a dedicated jig 15, and a load was applied at a speed of 10 mm / min so that a shear force was applied in a direction parallel to the bonded surface (the longitudinal direction of the aluminum plate). 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).

[0084] 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.

[0085] <Evaluation of Bond Strength (2) (Shear Test)> The bond strength of the metal-resin-metal bonded body was evaluated by measuring shear strength in accordance with JIS K 6850. Specifically, as shown in Figure 7, a metal-resin-metal bonded body 16, which was made by bonding two metal members 6 and 6' using a thermosetting adhesive (described below), was fixed to a dedicated jig 15, 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 perform a test to destroy 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).

[0086] Furthermore, the fracture surface after the shear strength evaluation was visually inspected to confirm the fracture morphology. If cohesive failure occurred in the adhesive and adhesive remained throughout the entire joint, it was judged as "resin failure" (good). If failure occurred at the interface between the metal component and the adhesive, it was judged as "interface failure" (poor).

[0087] <Airtightness evaluation> The airtightness of the metal-resin bonded body or the metal-resin-metal bonded body was evaluated by an air leak test. Specifically, as shown in FIG. 8 , a metal-resin bonded body 8, which was formed by bonding a metal member 6 and a resin molded body 7, was clamped and fixed in a dedicated airtight jig 20. Air was applied at a maximum positive pressure of 0.5 MPa and held for one minute. Thereafter, the presence or absence of air leakage was visually confirmed. Alternatively, as shown in FIG. 9 , a metal-resin-metal bonded body 16, which was formed by bonding two metal members 6 and 6′ using a thermosetting adhesive described below, was clamped and fixed in a dedicated airtight jig 20. Air was applied at a maximum positive pressure of 0.5 MPa and held for one minute. Thereafter, the presence or absence of air leakage was visually confirmed. In the dedicated airtight jig 20 described above, the metal-resin bonded body 8 or the metal-resin-metal bonded body 16 was clamped and fixed from above and below with an O-ring 18 interposed between the fixing jigs. With the metal-resin bonded body 8 or the metal-resin-metal bonded body 16 sandwiched between them, water 17 is present in the open portion on the upper side of the dedicated airtight jig 20, and air is present in the sealed portion on the lower side of the dedicated airtight jig 20. By applying air to the sealed portion through the ventilation pipe 19, it is possible to check whether air leaks through the metal-resin bonded body 8 or the metal-resin-metal bonded body 16 to the open portion side, based on whether air bubbles are generated from the bonded interface. If no air leaks were observed within the evaluation time, the result was evaluated as "pass (good)," and if an air leak was observed, the result was evaluated as "fail (poor)."

[0088] <Arithmetic mean surface roughness Ra> The surface roughness of the bonding surface was measured as the arithmetic mean roughness Ra using a Keyence VR-3200 one-shot 3D shape measuring instrument. The measurement was performed in a measurement range of 3600 x 2800 μm, with a magnification of 80x, no cutoff λs, no cutoff λc, and a reference length of 1, and the average value was taken as the measured value at 41 locations. The measurement was performed so that the striped trajectory of the laser light and the striped light irradiated from the measuring instrument's projection lens intersected at right angles.

[0089] [Example 1] <Production of metal components> A circular aluminum disk with a thickness of 2 mm, an outer diameter of 55 mm, and an inner diameter of 20 mm was cut out from a hollow extrusion of A5052 aluminum alloy (A5052-H34) that had been treated in accordance with ISO 19095 and the tempering code H34 specified in JIS H0001 to prepare the metal substrate.

[0090] Next, the surface to be processed of the aluminum disk was subjected to laser processing under the following conditions to form a bonding surface with the resin molded product. On the aluminum disk, the laser was irradiated concentrically from the inside to a 2.0 mm wide annular region, forming multiple marking patterns in that region consisting of multiple adjacent (parallel) concentric circles (curves). The laser processing conditions are summarized in Tables 2 and 3 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 D: 60 μm ·Irradiation interval P: 65μm Scanning speed: 340mm / s Number of scans (irradiations): 1 Number of rays: 30 / 2mm Energy density: 1.92J / mm 2 P / D:1.1

[0091] <Joining of resin molded bodies, production of metal-resin bonded bodies> The metal members (aluminum discs after laser treatment) on which the marking patterns were formed as described above were inserted into molds made in accordance with ISO 19095 using an injection molding machine (Nissei Plastic Industrial Co., Ltd., FNX1103-18A). Then, an aromatic nylon (manufactured by Mitsubishi Engineering Plastics Corporation, trade name: Reny (registered trademark), grade: XL1002U) with polyamide MXD10 as the base resin was used as the thermoplastic resin. This was injection molded 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 resulted in a resin molded body in the shape of a disc with a thickness of 2 mm and a diameter of 24 mm, with a circular joint with the inner diameter side of the aluminum disc having a joint width of 2.0 mm and a joint area of 138.2 mm. 2 A bonded body (metal-resin bonded body 8, FIG. 10) of an aluminum disk (metal member) 6 and a resin molded body 7 was produced.

[0092] <Evaluation> The metal-resin bonded body was evaluated for airtightness. The evaluation results are shown in Table 4.

[0093] [Examples 2 to 6] Among the laser treatment conditions, the irradiation interval P was changed to the conditions shown in Table 2, and accordingly, the number of irradiations (irradiations / 2 mm), energy density, and P / D were changed as shown in Table 2. Otherwise, marking patterns were formed in the same manner as in Example 1, and each metal member (aluminum disk) was produced, and each metal-resin bonded body for evaluation was also produced. The airtightness of each metal-resin bonded body was evaluated, and the evaluation results are shown in Table 4.

[0094] [Example 7] The laser processing conditions were changed to an output of 50.0 W, a frequency of 120 kHz, a scanning speed of 400 mm / s, and an irradiation interval P of 120 μm. As a result, except that the number of irradiations (irradiations / 2 mm), energy density, and P / D were changed as shown in Table 2, a marking pattern was formed in the same manner as in Example 1 to prepare a metal member (aluminum disk), and a metal-resin bonded body for evaluation was also prepared. The metal-resin bonded body was evaluated for airtightness. The evaluation results are shown in Table 4.

[0095] [Example 8] A hollow extrusion of A6063 aluminum alloy (A6063-T5) was processed in accordance with ISO19095 with the tempering code T5 specified in JIS H0001. A ring-shaped 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 prepared as metal substrates.

[0096] Next, among the laser processing conditions, the scanning speed was changed to 500 mm / s, and the irradiation interval P was changed to 70 μm. As a result, a marking pattern was formed by laser irradiation in the same manner as in Example 1, except that the number of irradiations (lines / 2 mm), energy density, and P / D were changed as shown in Table 2. For the annular aluminum disk, the laser was irradiated concentrically from the inside to a 2.0 mm wide annular region. For the circular aluminum disk, the laser was irradiated concentrically from the outer periphery to a 2.0 mm wide region. As a result, multiple marking patterns consisting of multiple adjacent (parallel) concentric circles (curves) were formed in each region of the annular aluminum disk and the circular aluminum disk.

[0097] A thermosetting adhesive (one-component heat-curing epoxy adhesive) (product name: Scotch-Weld (registered trademark) SW2214, manufactured by 3M Japan Ltd.) was used as the resin for the metal member (aluminum disc after laser processing) on which the marking pattern had been formed as described above. The adhesive was applied to the joining surface, adjusting the thickness with a SUS wire so that the adhesive was 0.2 mm. After applying the adhesive, the annular aluminum disc and the circular aluminum disc were bonded together, and a pressure of 0.01 MPa was applied. After the test piece temperature reached 150°C, the test piece was heated for 30 minutes. Under these adhesive conditions, the annular joint between the annular aluminum disc and the circular aluminum disc had a joint width of 2.0 mm and a joint area of 138.2 mm. 2A bonded body (metal-resin-metal bonded body 16, Figure 11) of a circular aluminum disk (metal member) 6 and a circular aluminum disk (metal member) 6' (a bonded body of a circular aluminum disk, a resin molded body, and a circular aluminum disk) was produced using an adhesive. The metal-resin-metal bonded body was evaluated for airtightness. The evaluation results are shown in Table 4.

[0098] [Example 9] The metal used was a rolled material of oxygen-free copper (C1020) specified in JIS H3100. Among the laser processing conditions, the scanning speed was changed to 400 mm / s, the number of scans to 5, and the irradiation interval P was changed to 90 μm. Consequently, the number of irradiations (lines / 2 mm), energy density, and P / D were changed as shown in Table 2. Furthermore, polyphenylene sulfide (PPS) (manufactured by Polyplastics Co., Ltd., trade name: DURAFIDE, grade: 1150MF1) was used as the thermoplastic resin. A marking pattern was otherwise formed in the same manner as in Example 1 to produce a metal member (copper disk), and a metal-resin bonded body for evaluation was also produced. The metal-resin bonded body was evaluated for airtightness. The evaluation results are shown in Table 4.

[0099] [Example 10] Among the laser treatment conditions, the irradiation interval P was changed to 90 μm. As a result, except that the number of irradiations (irradiations / 2 mm), energy density, and P / D were changed as shown in Table 2, a metal member (copper disk) and a metal-resin bonded body for evaluation were produced in the same manner as in Example 9. The metal-resin bonded bodies were also evaluated for airtightness. The evaluation results are shown in Table 4.

[0100] [Example 11] A stainless steel plate (SUS304) was used as the metal, and among the laser processing conditions, the number of scans was changed to two, and the irradiation interval P was changed to 90 μm. As a result, the number of irradiations (lines / 2 mm), energy density, and P / D were changed as shown in Table 2. In addition, polyphenylene sulfide (PPS) (manufactured by Polyplastics Co., Ltd., trade name: DURAFIDE, grade: 1150MF1) was used as the thermoplastic resin. A marking pattern was otherwise formed in the same manner as in Example 1, and a metal member (iron disk) was produced, and a metal-resin bonded body for evaluation was also produced. The metal-resin bonded body was evaluated for airtightness. The evaluation results are shown in Table 4.

[0101] [Example 12] Among the laser treatment conditions, the irradiation interval P was changed to 65 μm. As a result, the number of irradiations (iron / 2 mm), energy density, and P / D were changed as shown in Table 2. Otherwise, a metal member (iron disk) was produced in the same manner as in Example 11, and a metal-resin bonded body for evaluation was also produced. The metal-resin bonded body was also evaluated for airtightness. The evaluation results are shown in Table 4.

[0102] [Comparative Example 1] Among the laser processing conditions, the irradiation interval P was changed to 40 μm. As a result, the number of irradiations (irradiations / 2 mm), energy density, and P / D were changed as shown in Table 2. Otherwise, a marking pattern was formed in the same manner as in Example 1, and a metal member (aluminum disc) and a metal-resin bonded body for evaluation were produced. The metal-resin bonded body was evaluated for airtightness. The evaluation results are shown in Table 4.

[0103] [Comparative Examples 2 to 11] Among the laser treatment conditions, the irradiation interval P was changed to the conditions shown in Table 2, and accordingly, the number of irradiations (irradiations / 2 mm), energy density, and P / D were changed as shown in Table 2. Otherwise, marking patterns were formed in the same manner as in Comparative Example 1, and each metal member (aluminum disk) was produced, and a metal-resin bonded body for evaluation was also produced. The airtightness of each metal-resin bonded body was evaluated, and the evaluation results are shown in Table 4.

[0104] [Experimental Example 1] <Production of metal components> A rectangular aluminum plate measuring 1.5 mm thick, 18 mm wide, and 45 mm long was cut out from a hollow extrusion of A5052 aluminum alloy (A5052-H34) that had been processed in accordance with ISO 19095 and with the tempering code H34 specified in JIS H0001 to prepare the metal substrate.

[0105] Next, a laser treatment was performed on the surface to be processed of the aluminum plate under the following conditions to form a bonding surface with the resin molded body. For the aluminum plate, 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. The laser was irradiated linearly along the lateral direction of the aluminum plate to form multiple marking patterns consisting of parallel straight lines. Other laser treatment conditions were the same as in Example 1.

[0106] <Joining of resin molded bodies, production of metal-resin bonded bodies> Resin was injection molded onto the metal member (aluminum plate after laser treatment) on which the marking pattern had been formed as described above, to produce a bonded body (metal-resin bonded body 8, FIG. 12) of aluminum plate (metal member) 6 and resin molded body 7. The injection molding conditions were the same as in Example 1, except that the resin molded body 7 had a rectangular shape with a thickness of 3 mm, a width of 10 mm, and a length of 45 mm, and the area of the rectangular bonded portion between the aluminum plate and the resin molded body (bonding area) was 5 mm x 10 mm.

[0107] <Evaluation> The cross section of the metal-resin bonded body was evaluated. The results of cross section observation using an SEM are shown in Figure 13. Furthermore, the surface roughness Ra of the metal member (aluminum plate material after laser treatment) after the marking pattern was formed but before resin bonding was measured. The measurement results are shown in Table 5. The metal-resin bonded bodies were also evaluated for bonding strength, and the evaluation results are shown in Table 5.

[0108] [Experimental Examples 2-7] The laser treatment conditions were changed to the conditions shown in Table 2, similarly to Examples 2 to 7. Otherwise, marking patterns were formed in the same manner as in Experimental Example 1, and each metal member (aluminum plate material) and each metal-resin bonded body for evaluation were fabricated. Furthermore, evaluation was performed on the joint cross sections of the metal-resin joined bodies of Experimental Examples 4 and 7. The results of SEM observation of the cross section of Experimental Example 4 are shown in Fig. 14. The results of SEM observation of the cross section of Experimental Example 7 are shown in Fig. 15. Furthermore, the surface roughness Ra of each metal member was measured after the marking pattern was formed but before the resin molded body was joined. The measurement results are shown in Table 5. Furthermore, the bonding strength of each metal-resin bonded body was evaluated, and the evaluation results are shown in Table 5.

[0109] [Experimental Example 8] 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 with the tempering code T5 specified in JIS H0001 to prepare the metal substrates.

[0110] Next, the laser processing conditions were changed to the conditions listed in Table 2, similar to Example 8. For each of the two aluminum plates, a 6 mm x 25 mm rectangular region was irradiated with the laser in a striped pattern at the longitudinal end of one of the main surfaces. The laser was irradiated linearly along the short side of the aluminum plate to form multiple marking patterns consisting of parallel straight lines. Other than that, marking patterns were formed in the same manner as in Experimental Example 1, and metal members (aluminum plates) were produced.

[0111] A bonded body of aluminum plate materials (metal members) 6 and 6' (a bonded body of an aluminum plate material, a resin molded body, and an aluminum plate material) (metal-resin-metal bonded body 16, Figure 16) was produced using an adhesive in the same manner as in Example 8, except that the bonding area of the rectangular bonding portion between the two aluminum plate materials was changed to 6 mm x 25 mm for the metal member (aluminum plate material after laser treatment) on which the marking pattern had been formed as described above. The surface roughness Ra of the metal member after the marking pattern was formed and before the resin molded body (adhesive) was bonded was measured. The measurement results are shown in Table 5. The metal-resin-metal bonded bodies were also evaluated for bonding strength. The evaluation results are shown in Table 5.

[0112] [Experimental Examples 9 and 10] The metal used was a rolled material of oxygen-free copper (C1020) specified in JIS H3100. The laser treatment conditions were changed to those shown in Table 2, similarly to Examples 9 and 10. The thermoplastic resin used was polyphenylene sulfide (PPS) (manufactured by Polyplastics Co., Ltd., trade name: DURAFIDE, grade: 1150MF1). Aside from that, a marking pattern was formed in the same manner as in Experimental Example 1 to prepare a metal member (copper sheet material), and a metal-resin bonded body for evaluation was also prepared. An evaluation was carried out on the joint cross section of the laser-treated metal member before joining the resin molded article of Experimental Example 9. The results of observation of the cross section of Experimental Example 9 by SEM are shown in FIG. The surface roughness Ra of the metal member after the marking pattern was formed but before resin bonding was measured. The measurement results are shown in Table 5. The metal-resin bonded bodies were also evaluated for bonding strength, and the evaluation results are shown in Table 5.

[0113] [Experimental Examples 11 and 12] A stainless steel plate (SUS304) was used as the metal. The laser treatment conditions were changed to those shown in Table 2, as in Examples 11 and 12. Polyphenylene sulfide (PPS) (manufactured by Polyplastics Co., Ltd., trade name: DURAFIDE, grade: 1150MF1) was used as the thermoplastic resin. A marking pattern was otherwise formed in the same manner as in Experimental Example 1, and a metal member (iron plate) was produced, and a metal-resin bonded body for evaluation was also produced. The bonded cross section was evaluated for the laser-treated metal member before bonding the resin molded article of Experimental Example 11. The results of SEM observation of the cross section of Experimental Example 11 are shown in FIG. The surface roughness Ra of the metal member after the marking pattern was formed but before resin bonding was measured. The measurement results are shown in Table 5. The metal-resin bonded bodies were also evaluated for bonding strength, and the evaluation results are shown in Table 5.

[0114] [Comparative Experimental Examples 1-11] The laser treatment conditions were changed to the conditions shown in Table 2, similarly to Comparative Examples 1 to 11. Otherwise, a marking pattern was formed in the same manner as in Experimental Example 1, and a metal member (aluminum plate material) and a metal-resin bonded body for evaluation were produced. The bonded cross sections were evaluated for the metal-resin joined bodies of Comparative Experimental Examples 1 and 4. The results of SEM observation of the cross section of Comparative Experimental Example 1 are shown in Fig. 19. The results of SEM observation of the cross section of Comparative Experimental Example 4 are shown in Fig. 20. The surface roughness Ra of the metal member after the marking pattern was formed but before resin bonding was measured. The measurement results are shown in Table 5. The metal-resin bonded bodies were also evaluated for bonding strength, and the evaluation results are shown in Table 5.

[0115] [Table 2]

[0116] [Table 3]

[0117] [Table 4]

[0118] [Table 5]

[0119] [Consider] In Experimental Examples 1, 4, 7, 9, and 11, cross-sectional observation using an SEM confirmed the formation of marking patterns having concave and convex portions. Furthermore, in the region sandwiched between adjacent marking patterns, the convex portions included in the adjacent marking patterns were formed so as to contact and integrate with each other, and it was confirmed that no untreated area (laser-unirradiated area) was formed, exposing the metal substrate prior to laser irradiation. It was also observed that marking patterns having concave and convex portions with relatively large surface roughness were formed. It was also confirmed that the resin penetrated into the concave and convex portions of the marking patterns of the metal members and bonded them. Furthermore, the metal-resin joints of Experimental Examples 1 to 12 satisfied the shear strength values, and resin fracture occurred at the joint. These results demonstrate that laser treatment under conditions satisfying a predetermined P / D ratio can form marking patterns with desired cross-sectional shapes. It is believed that such marking patterns fully exerted the anchoring effect between the concave and convex portions and the resin, prevented fracture at the bonding interface, and provided sufficient bonding strength.

[0120] On the other hand, SEM cross-sectional observation of Comparative Experimental Example 1 confirmed that there were no areas not irradiated with the laser (untreated areas), but that the metal melted by laser irradiation had accumulated to cover the entire surface of the metal substrate on which the irregularities were formed, resulting in the formation of voids in the deposited areas. It was also observed that a marking pattern with relatively small surface roughness had been formed. Furthermore, Comparative Experimental Examples 1 to 3 had lower shear strength than Experimental Examples 1 to 7, resulting in interfacial fracture. From these results, it can be understood that when P / D is too small, the resin does not penetrate sufficiently into the irregularities, and the aforementioned voids are formed, resulting in fracture at the bonding interface and insufficient bonding strength.

[0121] Furthermore, SEM cross-sectional observation of Comparative Experimental Example 4 confirmed the formation of laser-unirradiated areas (untreated areas) (for example, the area indicated by reference numeral 21 in FIG. 20). Comparative Experimental Examples 4 to 11 had smaller surface roughness Ra than Experimental Examples 1 to 7. Comparative Experimental Examples 4 to 11 also had lower shear strength than Experimental Examples 1 to 7, resulting in interfacial fracture. From these results, it can be understood that when P / D is excessively large, untreated areas are formed and the interlocking effect of the uneven parts is insufficient, resulting in fracture at the bonding interface and insufficient airtightness. Furthermore, it can be understood from Comparative Experimental Examples 4 to 11 that as P / D increases, the area of laser-unirradiated areas (untreated areas) increases, resulting in a decrease in bonding strength.

[0122] The relationship between the laser processing conditions, the marking pattern, and the bonding strength has been explained above based on the evaluation results of the Experimental Examples and Comparative Experimental Examples. It is believed that in Examples 1 to 12, which were subjected to laser processing under laser processing conditions that resulted in the same P / D as in Experimental Examples 1 to 12, marking patterns with similar cross-sectional shapes were formed and sufficient bonding strength was achieved.

[0123] Next, in Examples 1 to 12, the evaluation of airtightness was passed. As explained with reference to the cross-sectional observation results by SEM in the experimental examples, by performing laser treatment under conditions that satisfy a predetermined P / D, it is possible to form a marking pattern without untreated areas (areas not irradiated with laser). This is understood to have enabled interaction between the unevenness of the metal substrate and the resin molded body across the entire bonding surface, thereby improving airtightness. In addition, it is understood that airtightness was achieved both inside and outside the marking pattern by forming multiple marking patterns consisting of a single continuous curve running adjacent to each other so that the start and end points of laser light irradiation coincide and do not intersect.

[0124] On the other hand, the airtightness evaluation was unacceptable in Comparative Examples 1 to 3. As explained with reference to the cross-sectional observation results by SEM in Comparative Experimental Example 1, when P / D is too small, metal molten by laser irradiation is deposited to cover the surface of the metal substrate, and voids are generated in the deposited area. In Comparative Examples 1 to 3, a marking pattern consisting of a single continuous curve that does not intersect was formed so that the start and end points of laser light irradiation coincided, but it is believed that air leaked from the voids in the deposited area, resulting in insufficient airtightness.

[0125] Furthermore, the airtightness evaluation was unacceptable in Comparative Examples 4 to 11. As explained with reference to the cross-sectional observation results by SEM in Comparative Experimental Example 4, when P / D is excessively large, non-laser-irradiated areas (untreated areas) are generated. In Comparative Examples 4 to 11, a marking pattern consisting of a single continuous curve that does not intersect was formed so that the start and end points of laser light irradiation coincided, but it is believed that air leaked from the untreated areas, resulting in insufficient airtightness. [Explanation of symbols]

[0126] 1...Start point and end point of laser irradiation, 2...Start point of laser irradiation, 3...End point of laser irradiation, 4...Hollow portion, 5...Opening end, 6 (6')...Metal member, 7...Resin molded body, 8...Metal-resin bonded body, 9...Marking pattern (where the start point and end point coincide), 10...(Intersecting) marking pattern, 11...Scanning direction, 12...Beam diameter, 13...Irradiation width, 14 (14')...Laser light trajectory, 15...Special jig for shear test, 16...Metal-resin-metal bonded body, 17...Water, 18...O-ring, 19...Air blowing tube, 20...Special airtight jig, 21...Laser unirradiated portion (untreated portion)

Claims

1. an irradiation step of irradiating a surface of a metal substrate made of metal with laser light to form a marking pattern having continuous concave and convex portions along an irradiation locus of the laser light on the surface of the metal substrate; A method for manufacturing a metal member in which a plurality of the marking patterns are formed on a surface of the metal substrate, comprising: the marking pattern is made up of a single continuous straight line or curve so that the start point and end point of the irradiation of the laser light coincide with each other and do not intersect; In the irradiation step, the energy density (J / mm 2 ) is calculated from the laser light output W (W), the number of scans N (times), the irradiation interval P (mm), and the scan speed V (mm / s) using formula (A2). When performing laser treatment on the metal substrate containing aluminum as the main metal, the laser treatment conditions for forming the marking pattern are set so that the energy density is 0.5 J / mm 2 or more and 5 J / mm 2 or less. When performing laser treatment on the metal substrate containing iron as the main metal, the laser treatment conditions for forming the marking pattern are set so that the energy density is 0.5 J / mm 2 or more and 10 J / mm 2 or less. When performing laser treatment on the metal substrate containing copper as the main metal, the laser treatment conditions for forming the marking pattern are set so that the energy density is 0.5 J / mm 2 or more and 20 J / mm 2 or less. Energy density = (W × N) / (P × V) Equation (A2) In the irradiation step, the laser light is irradiated under the set laser processing conditions, a laser beam having a beam diameter D of 20 μm to 200 μm, an irradiation interval P of the laser beam having a beam diameter D of 20 μm to 200 μm, and a ratio (P / D) of the irradiation interval P to the beam diameter D of 1.1 or more and 2 or less.

2. the metal substrate has a surface on which the irregularities are formed, the surface of the metal substrate having recesses formed by the metal irradiated with the laser light diffusing outward from the center of the laser light irradiation, and protrusions formed by the metal diffusing from the recesses and accumulating around the recesses; The method for manufacturing a metal component according to claim 1, characterized in that, in the area on the surface of the metal component sandwiched between adjacent marking patterns, the convex portions included in the adjacent marking patterns are formed so as to come into contact with each other and become integrated, and no untreated area is formed in which the metal base material is exposed before being irradiated with the laser light.

3. the metal substrate has a hollow shape with a hollow portion therein and an open end portion surrounding the hollow portion; 3. The method for manufacturing a metal member according to claim 1, wherein in the irradiating step, the laser light is irradiated so that the marking pattern is formed on the opening edge.

4. 4. The method for manufacturing a metal member according to claim 3, wherein the laser beam is irradiated at the opening end so as not to form a marking pattern that communicates with both sides of the marking pattern.

5. The method for manufacturing a metal member according to any one of claims 1 to 4, characterized in that the laser light is irradiated so that the arithmetic mean roughness Ra of the surface of the metal member obtained through the irradiation step is 24 μm to 200 μm.

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, comprising the steps of: A method for manufacturing a metal-resin bonded body, characterized in that in the resin molding step, the metal member and the resin molded body are bonded in a state in which resin has penetrated into the uneven portions of the marking pattern.

8. 8. The method for producing a metal resin bonded body according to claim 7, wherein in the resin molding step, a resin composition containing a thermoplastic resin or a thermosetting resin is molded onto the metal member.

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