JP7688871B2 - Method for manufacturing composite member of plated metal and resin and composite member - Google Patents

Description

The present invention relates to a composite member that includes a base material, a metal coating that covers at least a portion of the base material, and a resin bonded to the surface of the metal coating.

Patent Document 1 discloses a technology relating to a composite member that includes an aluminum member having an aluminum hydroxide film formed on its surface and a resin member that is in direct contact with the surface of the aluminum member having the aluminum hydroxide film formed thereon (see, for example, FIG. 1 of Patent Document 1).

JP 2020-131492 A

However, when adopting the technology of Patent Document 1, the material constituting the base material is limited to aluminum.

One aspect of the present invention has been made in consideration of the above-mentioned problems, and its purpose is to expand the variety of materials that can be used to form the base material in a composite member formed by bonding a base material and a resin.

In order to solve the above problems, the manufacturing method of a composite member according to the first aspect of the present invention is a manufacturing method of a composite member including a base material, a metal coating covering at least a portion of the base material, and a resin bonded to the surface of the metal coating. This manufacturing method of a composite member includes a removal process for removing an oxide film covering the surface of the metal coating, a hot water treatment process for performing a hot water treatment on the surface on which the removal process has been performed, and a joining process for joining a resin to the surface on which the hot water treatment process has been performed.

In order to solve the above problems, the composite member according to the sixth aspect of the present invention comprises a base material, a metal coating covering at least a portion of the base material, the metal coating having a needle-shaped structure on its surface composed of at least one of a hydroxide and an oxide of the metal that constitutes the metal coating, and a resin bonded to the surface of the metal coating.

According to one aspect of the present invention, it is possible to expand the variety of materials that can be used to form the base material in a composite component formed by bonding a base material and a resin.

1 is a perspective view of a composite material according to a first embodiment of the present invention; FIG. 2 is a cross-sectional view of the composite member shown in FIG. 2A and 2B are SEM images of the bonded region shown in FIG. 1 before the resin is bonded. The top SEM image is at a magnification of 20,000 times, and the bottom SEM image is at a magnification of 40,000 times. FIG. 2 is a cross-sectional view of a modified example of the composite member shown in FIG. 1 . The left figure is a flow chart of a method for manufacturing a composite member according to a second embodiment of the present invention, and the right figure is a cross-sectional view of the joining area after each step included in the method for manufacturing a composite member shown in the left figure is performed. 6 is a flowchart of a modified example of the removal step included in the manufacturing method of the composite member shown in the left diagram of FIG. 5 .

First Embodiment
A composite member 10 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a perspective view of the composite member 10. FIG. 2 is a cross-sectional view of the composite member 10, taken along the line AA' shown in FIG. 1. FIG. 3 is a scanning electron microscope (SEM) image of the joining region 122 of the composite member 10 before the resin member 13 is joined. The upper SEM image has a magnification of 20,000 times, and the lower SEM image has a magnification of 40,000 times. The state before the resin member 13 is joined means a state in which the hot water treatment step S13 shown in FIG. 5 has been performed, and the joining step S14 shown in FIG. 5 has not been performed. The manufacturing method M10 of the composite member including the hot water treatment step S13 and the joining step S14 will be described later in the second embodiment.

As shown in FIG. 1, the composite member 10 includes a base material 11, a metal coating 12, and a resin member 13.

<Base material and metal coating>
As shown in Fig. 1, the base material 11 is formed into a plate shape. In this embodiment, high tensile steel is used as the material constituting the base material 11. However, the material constituting the base material 11 is not limited to high tensile steel, and can be appropriately selected depending on the application. The material constituting the base material 11 may be any of metal, glass, ceramic, and resin. That is, in the composite member 10, the base material 11 is not limited to the plated metal described in the title of the invention.

In this embodiment, as shown in FIG. 1, a metal coating 12 is formed on one of a pair of main surfaces constituting the base material 11. That is, in this embodiment, one of the main surfaces, which is a part of the base material 11, is covered with the metal coating 12. However, the area of the base material 11 covered with the metal coating 12 only needs to include a joining area 122, which is an area to which the resin member 13 described below is joined, and may be a part of the surface of the base material 11 or the entire surface of the base material 11.

In this embodiment, zinc is used as the material constituting the metal coating 12. Also, in this embodiment, the metal coating 12 is formed on one main surface of the base material 11 by using a plating method. However, the material constituting the metal coating 12 is not limited to zinc as long as it is a metal. It is preferable that the material constituting the metal coating 12 is a material that can be used to form the metal coating 12 by using a plating method. Also, the method of forming the metal coating 12 on one main surface of the base material 11 is not limited to a plating method. That is, in the composite member 10, the metal coating 12 is not limited to the plating or plating film described in the title of the invention.

As described above, in this embodiment, zinc-plated high-tensile steel plate called SPFC780 is used as the base material 11 and the metal coating 12. The thickness of the metal coating 12 is not limited, but is typically 1 μm or more and 50 μm or less. In this embodiment, the thickness of the metal coating 12 is 25 μm.

<Resin material>
As shown in FIG. 1, the resin member 13 is molded into a rectangular parallelepiped shape. In this embodiment, polyphenylene sulfide (PPS) resin is used as the material constituting the resin member 13. However, the material constituting the resin member 13 is not limited to PPS resin as long as it is a resin, and can be appropriately selected depending on the application. The material constituting the resin member 13 may be engineering plastic, super engineering plastic, or fiber reinforced plastic including glass fiber, carbon fiber, etc., other than PPS resin. In addition, the material constituting the resin member 13 may be a resin suitable as an adhesive. An example of a resin suitable as an adhesive is epoxy resin.

<Joining area>
Hereinafter, a region where the metal coating 12 and the resin member 13 overlap when the main surface 121 of the metal coating 12 is viewed from the normal direction of the main surface 121 is referred to as a bonding region 122. In Fig. 1, the bonding region 122 is illustrated by a virtual line (two-dot chain line).

In the second embodiment, which will be described with reference to FIG. 5, the area including the joining area 122 of the main surface 121 is subjected to a removal process S12 using blast processing and a hot water treatment process S13.

By subjecting the bonding area 122 to the removal process S12 using blasting, the natural oxide film that had formed on the surface of the bonding area 122 is removed, and a micro-sized uneven structure 123 is formed on the surface of the bonding area 122 (see Figure 2).

In addition, by carrying out the hot water treatment process S13 after the removal process S12, a needle-like structure 124 composed of zinc hydroxide and oxide is formed on the surface of the uneven structure 123 of the bonding region 122 (see FIG. 2). However, the needle-like structure 124 may be composed of zinc hydroxide and oxide, or may be composed of at least one of zinc hydroxide and oxide. A scanning electron microscope (SEM) image of the needle-like structure 124 formed on the surface of the uneven structure 123 of the bonding region 122 is shown in FIG. 3. The upper SEM image has a magnification of 20,000 times, and the lower SEM image has a magnification of 40,000 times.

When comparing zinc hydroxide with zinc oxide, zinc hydroxide has higher wettability with resin. Therefore, when the needle-shaped structure 124 is composed of zinc hydroxide and oxide, the bonding strength between the metal coating 12 and the resin member 13 can be increased by increasing the proportion of hydroxide in the needle-shaped structure 124.

The resin member 13 is injection molded so that a portion of the resin member 13 overlaps the bonding region 122, thereby bonding to the bonding region 122. When the resin constituting the resin member 13 is injected into the bonding region 122, the resin has fluidity. Therefore, the fluid resin fills the gaps in the needle-like structures generated by the hot water treatment step S13, and the injected resin soon hardens (see FIG. 2).
Thus, in the composite member 10, at least a part of the base material 11 is covered with the metal coating 12, and the resin member 13, which is a hardened resin, is joined to the joining region 122, which is at least a part of the main surface 121 of the metal coating 12. Therefore, the material constituting the base material 11 may be a material that can cover a part of the surface with the metal coating 12. In other words, the material of the base material 11 may be a material that can form the metal coating 12 on the surface by a plating method. Therefore, the material constituting the base material 11 is not limited to aluminum as in Patent Document 1, so that the composite member 10 can expand the variation of materials that can constitute the base material. Furthermore, in the composite member 10, even if at least a part of the main surface of the base material 11 is covered with the metal coating 12, the anchor effect can be obtained in the same way as in the technology of Patent Document 1, so that the joining strength between the metal coating 12 and the resin member 13 can be increased to the same level as in the technology of Patent Document 1.

(Arithmetic mean slope and root mean square slope)
In the bonding region 122, the arithmetic mean slope RΔa of the main surface 121 is preferably 0.10 to 0.60, more preferably 0.15 to 0.55, and particularly preferably 0.17 to 0.50. In addition, in the bonding region 122, the root mean square slope RΔq of the main surface 121 is preferably 0.20 to 0.70, more preferably 0.25 to 0.65, and particularly preferably 0.27 to 0.60.

The arithmetic mean slope RΔa and the root mean square slope RΔq are both used as indicators of how much slope there is in a small space.

The smaller the arithmetic mean slope RΔa, the smaller the joint strength tends to be. When the arithmetic mean slope RΔa is 0.10 or more, a practical joint strength of about 12 MPa can be obtained, and when the arithmetic mean slope RΔa is 0.15 or more, a more practical joint strength of about 20 MPa can be obtained. In particular, when the arithmetic mean slope RΔa is 0.17 or more, sufficient joint strength can be obtained for welding structural parts of automobiles, etc. Also, when the arithmetic mean slope RΔa is 0.60 or less, the removal step S12 can be performed by blasting. In particular, when the arithmetic mean slope RΔa is 0.55 or less, the removal step S12 can be easily performed by blasting, and when the arithmetic mean slope RΔa is 0.50 or less, roughening by blasting is even easier.

Similarly, in the case of the root-mean-square slope RΔq, the smaller the root-mean-square slope RΔq, the smaller the joint strength is. When the root-mean-square slope RΔq is 0.20 or more, a practical joint strength of about 12 MPa can be obtained, and when the root-mean-square slope RΔq is 0.25 or more, a more practical joint strength of about 20 MPa can be obtained. In particular, when the root-mean-square slope RΔq is 0.27 or more, sufficient joint strength can be obtained for welding structural parts such as automobiles. In addition, when the root-mean-square slope RΔq is 0.70 or less, the removal step S12 by blast processing can be performed. In particular, when the root-mean-square slope RΔq is 0.65 or less, the removal step S12 by blast processing can be easily performed, and when the root-mean-square slope RΔq is 0.60 or less, the removal step S12 by blast processing can be performed even more easily.

(Thickness of the hydroxide and oxide layer)
The thickness t (see FIG. 2) of the layer made of hydroxide and oxide including the needle-like structure 124 is preferably 50 nm to 2000 nm, more preferably 100 nm to 1000 nm. In this embodiment, the thickness t is 500 nm.

If the thickness t is less than 50 nm, it is difficult to obtain a practical bonding strength. This is because the anchoring effect obtained is small. On the other hand, if the thickness t is more than 2000 nm, the structure of at least one of the hydroxide and oxide is likely to have a porous structure instead of a needle-like structure. In that case, it is difficult for the resin to penetrate into the porous structure, making it difficult to obtain a practical bonding strength. This is also because the anchoring effect obtained is small. Therefore, by making the thickness t 50 nm or more and 2000 nm or less, the hydroxide and oxide structures can be made into a needle-like structure suitable for obtaining an anchoring effect, and as a result, the bonding strength can be increased.

If the thickness t is less than 100 nm, the anchor effect is insufficient and it is difficult to obtain a practical bonding strength. Furthermore, if the thickness t exceeds 1000 nm, the hydroxide film becomes brittle and is prone to breakage when a load is applied. Therefore, by making the thickness t 100 nm or more and 1000 nm or less, it is possible to ensure a practical bonding strength and make it difficult for the hydroxide film to break when a load is applied.

<Applications of composite materials>
Examples of applications for the composite member 10 include structural members for automobiles (eg, suspension members) and electrical components.

When the composite member 10 is used as part of a structural member, it is preferable to use zinc-plated high-tensile steel plate as the base material 11 and the metal coating 12, and to use engineering plastics, super engineering plastics, etc. as the material that constitutes the resin member 13.

When the composite member 10 is used as part of an electrical component, it may be a metal part such as a terminal molded with resin. In this case, it is preferable to use copper with a plated surface as the base material 11 and the metal coating 12, and to use any one of PPS (polyphenylene sulfide) resin, PBT (polybutylene terephthalate) resin, and PPA (polyphthalamide) resin as the material constituting the resin member 13.

Simply molding a metal (e.g., copper) terminal with resin is likely to result in gaps at the interface between the metal and resin, allowing moisture from the atmosphere to easily penetrate through the gaps. Electrical components such as motors and power control units dislike moisture. For this reason, in the past, the interface between the terminal and resin was further sealed with epoxy resin or the like to prevent moisture from penetrating. With the composite member 10, the anchor effect makes it difficult for gaps to form at the interface between the copper and resin, so sealing with epoxy resin or the like can be omitted. In other words, simply by molding a metal component such as a terminal with resin, the inside of the mold can be sealed and airtightness can be increased.

<Modification>
A composite member 20, which is a modified example of the composite member 10, will be described with reference to Fig. 4. Fig. 4 is a cross-sectional view of the composite member 20, which is a modified example of the composite member 10.

In the composite member 10, the resin member 13 formed by injection molding was joined to the joining area 122 of the metal coating 12. In the composite member 20, two sets of high tensile steel plates, a base material 11A and a metal coating 12A, and a base material 11B and a metal coating 12B, are used. The base material 11A and a metal coating 12A, and the base material 11B and a metal coating 12B are both configured in the same way as the base material 11 and the metal coating 12 of the composite member 10.

In addition, in the composite member 20, the metal coating 12A and the resin member 13 are joined together by interposing a resin member 13, which functions as an adhesive, between the joining region 122A in the metal coating 12A and the joining region 122B in the metal coating 12B, and the metal coating 12A and the resin member 13 are joined together.

In this way, the composite member 20 can be said to be composed of two sets of composite members 10, composite members 10A and 10B, which have a common resin member 13. The composite member 20 thus composed is also included in the scope of the present invention.

Second Embodiment
A method M10 for manufacturing a composite member according to a second embodiment of the present invention will be described with reference to Figs. 5 and 6. The left diagram in Fig. 5 is a flowchart of the method M10 for manufacturing a composite member. The right diagram in Fig. 5 is a cross-sectional view of a bonding region 122 after carrying out each of steps S11 to S14 included in the method M10 for manufacturing a composite member shown in the left diagram. Note that the reference numeral "122" of the bonding region 122 is omitted in the right diagram in Fig. 5. The reference numeral "122" is shown in the cross-sectional view in Fig. 2. Fig. 6 is a flowchart of a removal step S12A, which is a modified example of the removal step S12 included in the manufacturing method M10.

Furthermore, in the following, the manufacturing method M10 of the composite member will be simply referred to as manufacturing method M10. Manufacturing method M10 can be suitably used to manufacture the composite member 10 described in the first embodiment. The composite member 10 is a composite member including a base material 11, a metal coating 12 that covers at least a portion of the base material 11, and a resin member 13 that is joined to a joining region 122 that is at least a portion of the surface of the metal coating 12.

In this embodiment, manufacturing method M10 is described as a method for manufacturing a composite material 10. As described in the first embodiment, high-tensile steel plate is used as the base material 11.

As shown in FIG. 5, manufacturing method M10 includes a plating process S11, a removal process S12, a hot water treatment process S13, and a joining process S14.

<Plating process>
The plating step S11 is a step of forming a metal coating 12 on one main surface of the base material 11 by plating (see the cross-sectional view of "S11" in the right diagram of FIG. 5).

In this embodiment, one of the main surfaces, which is a part of the base material 11, is covered with the metal coating 12. However, the area of the base material 11 covered with the metal coating 12 only needs to include the bonding area 122 shown in FIG. 1, and may be a part of the surface of the base material 11 or the entire surface of the base material 11.

In this embodiment, zinc is used as the material constituting the metal coating 12. However, the material constituting the metal coating 12 is not limited to zinc as long as it is a metal. It is preferable that the material constituting the metal coating 12 is a material from which the metal coating 12 can be formed using a plating method. However, the method of forming the metal coating 12 on one main surface of the base material 11 is not limited to the plating method. In that case, step S11 can be considered a metal coating formation step rather than a plating step.

When a metal plate (e.g., a zinc-plated high-tensile steel plate) on which a metal coating 12 has already been formed on the surface of the base material 11 is used as the starting material for manufacturing method M10, the plating step S11 can be omitted.

<Removal process>
When the base material 11 and the metal coating 12 are left in the air for a long period of time (for example, a period longer than three days), a natural oxide film is often formed on the main surface 121 of the metal coating 12. The removal step S12 is a step of removing the natural oxide film that covers the main surface 121, which is the surface of the metal coating 12. The natural oxide film is one form of an oxide film.

In this embodiment, in the removal step S12, blasting is used to remove the natural oxide film. By using blasting, it is possible to form a micro-sized uneven structure 123 on the surface while removing the natural oxide film (see the cross-sectional view of "S12" in the right diagram of Figure 5). Therefore, a main surface 121 with high metal activity is obtained, which can provide a high anchor effect by carrying out the hot water treatment step S13 described later.

In blast processing, the particle size of the abrasive material is preferably 10 μm or more and 710 μm or less, more preferably 20 μm or more and 500 μm or less, and particularly preferably 30 μm or more and 300 μm or less. The abrasive pressure is preferably 0.05 MPa or more and 2.0 MPa or less, more preferably 0.3 MPa or more and 1.5 MPa or less, and particularly preferably 0.5 MPa or more and 1.0 MPa or less.

When a natural oxide film of the metal (zinc in this embodiment) constituting the metal coating 12 is formed on the main surface 121 of the metal coating 12, the particle diameter of the spray material is 10 μm or more, so that a micro-sized uneven structure 123 can be formed on the main surface 121. In addition, the particle diameter of the spray material is 300 μm or less, so that the possibility of the metal coating 12 being damaged due to the blasting process can be reduced. When the particle diameter of the spray material is 10 μm or more and 710 μm or less, the spray pressure is 0.05 MPa or more and 2.0 MPa or less, so that the natural oxide film can be removed by the blasting process, the micro-sized uneven structure 123 can be formed on the main surface 121, and the possibility of the metal coating 12 being damaged can be reduced. Metal oxide films often have low wettability with resin. Therefore, by performing hot water treatment after removing the natural oxide film, the bonding strength of the composite member 10 can be increased to the same level as that of the technology of Patent Document 1. Examples of damage to the metal coating 12 that may occur when blasting is performed under inappropriate conditions include the penetration of the metal coating 12 by the abrasive material and the peeling of the metal coating 12 from the main surface of the base material 11. These conditions for blasting are suitable when the thickness of the metal coating 12 is 1 μm or more and 50 μm or less. By making the thickness of the metal coating 12 1 μm or more, it is possible to reliably reduce the possibility of the metal coating 12 being damaged while forming a micro-sized uneven structure 123. The thickness of 50 μm is a typical upper limit value for the thickness of the metal coating 12 produced using a plating method.

(Modification of the Removal Step)
In addition, in a removal step S12A, which is a modification of the removal step S12, an acid treatment can be used instead of the blasting process to remove the native oxide film (see FIG. 6). The removal step S12A includes an ultrasonic cleaning step S121 and an acid treatment step S122.

The ultrasonic cleaning process S121 is a process for ultrasonically cleaning the main surface 121 of the metal coating 12.

The acid treatment step S122 is a step of performing an acid treatment on the main surface 121. The acid treatment is also called pickling. In this modified example, hydrochloric acid is used as the acid solution used in the acid treatment. However, the acid solution used in the acid treatment is not limited to hydrochloric acid and can be selected as appropriate.

The main surface 121 of the metal coating 12 from which the natural oxide film has been removed using acid treatment is likely to have smaller irregularities than the main surface 121 from which the natural oxide film has been removed using blasting. Therefore, even if the thickness of the metal coating 12 is thin, the natural oxide film can be removed without damaging the metal coating 12.

<Hot water treatment process>
The hot water treatment step S13 is a step of performing a hot water treatment on the main surface 121 that has been subjected to the removal step S12. By performing the hot water treatment step S13, the zinc that constitutes the main surface 121 is hydroxide or oxidized as shown in the following chemical formula. As a result, a needle-like structure composed of at least one of the hydroxide and oxide of zinc that constitutes the metal coating 12 is formed on the main surface 121 on which the uneven structure 123 is formed (see the cross-sectional view of "S13" in the right diagram of FIG. 5). The needle-like structure is shown in FIG. 3, as described in the first embodiment.

Zn+2H ₂ O→Zn(OH) ₂ +H ₂
Zn(OH) ₂ →ZnO+H ₂ O

The temperature of the water used in the hot water treatment step S13 is preferably 50°C or more and 100°C or less, more preferably 60°C or more and 95°C or less, and particularly preferably 70°C or more and 90°C or less. The treatment time in the hot water treatment is preferably 10 seconds or more and 100 minutes or less, more preferably 30 seconds or more and 80 minutes or less, and particularly preferably 1 minute or more and 60 minutes or less.

If the temperature of the water used in the hot water treatment step S13 is less than 50°C, at least one of the metal hydroxides and oxides that make up the metal coating will not grow sufficiently. This reduces the anchor effect obtained, making it difficult to increase the bonding strength. In addition, hot water at 100°C or less can be obtained under atmospheric pressure, making this easy to achieve.

In addition, if the treatment time in the hot water treatment step S13 is less than 10 seconds, at least one of the hydroxides and oxides of the metal (zinc in this embodiment) that constitutes the metal coating 12 does not grow sufficiently. This reduces the anchor effect obtained, making it difficult to increase the bonding strength. It has also been found that the thickness t (see FIG. 2) of the layer consisting of at least one of the hydroxides and oxides of the metal that constitutes the metal coating 12 tends to saturate when the treatment time exceeds 100 minutes. Therefore, by setting the treatment time to 100 minutes or less, the hot water treatment can be carried out efficiently.

The electrical conductivity of the water used in the hot water treatment step S13 is preferably 0.05 μS/cm or more and 10 μS/cm or less, more preferably 0.08 μS/cm or more and 5 μS/cm or less, and particularly preferably 0.1 μS/cm or more and 1 μS/cm or less.

A high electrical conductivity of water means that the concentration of impurities (particularly metal ions) contained in the hot water is high. If the electrical conductivity of the water exceeds 10 μS/cm (i.e., if the concentration of impurities is too high), the reproducibility of the shape and size of at least one of the zinc hydroxides and oxides formed by the hot water treatment tends to decrease. As a result, the bonding strength of the composite member 10 tends to decrease.

In addition, the lower the electrical conductivity of the water, the higher the bond strength described above. However, it has been found that the bond strength tends to saturate when the electrical conductivity falls below 0.05 μS/cm. Therefore, by setting the lower limit of the preferred range of the electrical conductivity of water at 0.05 μS/cm, it is possible to prevent the waste of costs involved in removing impurities contained in the hot water.

<Joining process>
The joining step S14 is a step of joining the resin member 13 to the surface of the joining region 122 where the hot water treatment step S13 has been performed. In this embodiment, the resin member 13 is molded using an injection molding method so that a part of the resin member 13 overlaps the joining region 122. When the resin constituting the resin member 13 is injected into the joining region 122, the resin has fluidity. Therefore, the resin having fluidity fills the gaps of the needle-like structure generated by the hot water treatment step S13, and the injected resin eventually hardens (see the cross-sectional view of "S14" in the right diagram of FIG. 5). Therefore, in the composite member 10, even if at least a part of the main surface of the base material 11 is covered with the metal coating 12, the anchor effect can be obtained in the same manner as in the technique of Patent Document 1, so that the joining strength between the metal coating 12 and the resin member 13 can be increased to the same extent as in the technique of Patent Document 1.

The method for joining the resin member 13 to the surface of the joining region 122 in the joining step S14 is not limited to injection molding, but may be, for example, induction heating compression molding or press molding. Also, as described for the composite member 20 with reference to FIG. 4, a method using a resin that functions as an adhesive, such as an epoxy resin, may be used.

[Additional Notes]
The present invention is not limited to the first and second embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in the different embodiments are also included in the technical scope of the present invention.

[First and second embodiments]
The effects of the first and second embodiments of the present invention will be described while comparing them with the first and second experimental examples.

In the first embodiment, the second embodiment, the first experimental example, and the second experimental example, a zinc-plated high-tensile steel sheet was used as the starting material for manufacturing the composite member. Therefore, the base material 11 is a high-tensile steel sheet, and the material constituting the metal coating 12 is zinc. The thickness of the metal coating 12 made of zinc is 25 μm.

In the first embodiment, the composite member 10 was manufactured by carrying out the manufacturing method M10 shown in FIG. 5. That is, in the removal step S12, the natural oxide film was removed by blasting. The conditions for the blasting were a particle diameter of the abrasive material of 106 to 125 μm and a spray pressure of 1.0 MPa. The conditions for the hot water treatment in the hot water treatment step S13 were a water temperature of 75° C. and a treatment time of 40 minutes. As a result, the thickness t (see FIG. 2) of the layer consisting of hydroxides and oxides including the needle-like structure 124 was 500 nm. In the joining step S14, the resin member 13 made of PPS resin was directly joined to the joining area 122 of the metal coating 12 that had been subjected to the hot water treatment step S13 by using an injection molding method. The injection molding conditions were a mold temperature of 140°C, a resin temperature of 260°C, an injection speed of 10 mm/sec, a holding pressure of 50 MPa, and a holding time of 10 seconds.

In the second example, the manufacturing method M10 was used as a base, and the removal step S12A shown in FIG. 6 was carried out instead of the removal step S12. That is, in the second example, an acid treatment was used to remove the natural oxide film formed on the surface of the metal coating 12. In this acid treatment, a hydrochloric acid solution with a concentration of 10% was used as the hydrochloric acid solution in which the high tensile steel sheet was immersed. The treatment time for the acid treatment was set to 10 seconds.

In the first experimental example, the hot water treatment step S13 was omitted based on the first embodiment. Similarly, in the second experimental example, the hot water treatment step S13 was omitted based on the second embodiment.

The bond strength (shear strength) of the composite members manufactured using the first embodiment, the second embodiment, the first experimental example, and the second experimental example configured in this manner was measured using a test method conforming to ISO 19095.

Table 1 below shows the key points of the first embodiment, the second embodiment, the first experimental example, and the second experimental example, as well as the shear strength of each composite member.

熱水処理工程Ｓ１３を実施した第１の実施例および第２の実施例においては、各複合部材においていずれも２５ＭＰａ以上となるせん断強度が得られた。

In the first and second examples in which the hot water treatment step S13 was carried out, a shear strength of 25 MPa or more was obtained in each composite member.

In the first experimental example, in which the natural oxide film was removed using blasting and the hot water treatment step S13 was omitted, a shear strength of 14 MPa was obtained for the composite member. This shear strength was significantly lower than the shear strength of 31 MPa obtained in the first example.

In the second experimental example, in which the natural oxide film was removed using acid treatment and the hot water treatment step S13 was omitted, the resin member peeled off from the high-tensile steel plate immediately after the joining step S14 was performed. In other words, poor joining was observed in the composite member manufactured using the second experimental example.

[Third and fourth embodiments]
Based on the first and second examples, the third and fourth examples are examples in which press molding is used instead of injection molding in the joining step S14. In the press molding in the third and fourth examples, a resin member 13 made of carbon fiber reinforced thermoplastic resin (CFRTP manufactured by Toray Coatex) is directly joined to the joining region 122 of the metal coating 12. The press molding conditions were a molding temperature of 220°C, a molding pressure of 5 MPa, and a holding time of 5 minutes.

The third and fourth experimental examples were based on the third and fourth examples, respectively, but omitted the hot water treatment step S13.

The bonding strength (shear strength) of the composite members manufactured using the third embodiment, the fourth embodiment, the third experimental example, and the fourth experimental example configured in this manner was measured using a test method based on JIS K6850 "tensile shear adhesive strength test." The width of the bonding area 122 was 25 mm, and the length of the bonding area 122 was 12.5 mm.

Table 2 below shows the shear strength for the third embodiment, the fourth embodiment, the third experimental example, and the fourth experimental example.

熱水処理工程Ｓ１３を実施した第３の実施例および第４の実施例においては、各複合部材においていずれも２５ＭＰａ以上となるせん断強度が得られた。

In the third and fourth examples in which the hot water treatment step S13 was carried out, a shear strength of 25 MPa or more was obtained in each composite member.

In the third experimental example, in which the natural oxide film was removed using blasting and the hot water treatment step S13 was omitted, a shear strength of 16 MPa was obtained for the composite member. This shear strength was significantly lower than the shear strength of 32 MPa obtained in the third example.

In the fourth experimental example, in which the natural oxide film was removed using acid treatment and the hot water treatment step S13 was omitted, the resin member peeled off from the high-tensile steel plate immediately after the joining step S14 was performed. In other words, poor joining was observed in the composite member manufactured using the fourth experimental example.

10, 10A, 10B Composite member 11, 11A, 11B Base material 12, 12A, 12B Metal coating 121 Principal surface 122, 122A, 122B Bonding area 123 Uneven structure 124 Acicular structure 13 Resin member (resin)
20 Composite material

Claims (9)

A method for producing a composite member including a base material, a metal coating covering at least a portion of the base material, and a resin bonded to a surface of the metal coating, the method comprising the steps of:
a removing step of removing an oxide film covering a surface of the metal coating;
a hot water treatment step of subjecting the surface on which the removing step has been performed to a hot water treatment;
A bonding step of bonding a resin to the surface that has been subjected to the hot water treatment step.
A method for producing a composite member comprising the steps of: The removing step is a step of subjecting the surface to a blasting process,
In the blasting process, the particle diameter of the abrasive is 10 μm or more and 710 μm or less, and the abrasive pressure is 0.05 MPa or more and 2.0 MPa or less.
The method for producing a composite member according to claim 1 . The removing step is a step of subjecting the surface to an acid treatment.
The method for producing a composite member according to claim 1 . In the hot water treatment step, the water temperature is 50° C. or more and 100° C. or less, and the treatment time is 10 seconds or more and 100 minutes or less.
A method for producing a composite member according to any one of claims 1 to 3. In the hot water treatment step, the electrical conductivity of the water is 0.05 μS/cm or more and 10 μS/cm or less.
A method for producing a composite member according to any one of claims 1 to 4. A base material;
a metal coating covering at least a portion of the base material, the metal coating having a needle-shaped structure on a surface thereof, the needle-shaped structure being made of at least one of a hydroxide and an oxide of a metal constituting the metal coating;
and a resin bonded to the surface of the metal coating.
A composite member characterized by: The arithmetic mean slope of the surface is 0.10 or more and 0.60 or less;
7. A composite member according to claim 6. The root mean square slope of the surface is greater than or equal to 0.20 and less than or equal to 0.70.
8. A composite member according to claim 6 or 7. The thickness of the layer including the needle-like structure and including at least one of the hydroxide and the oxide is 50 nm or more and 2000 nm or less.
The composite material according to any one of claims 6 to 8.

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