JP7499223B2 - Metal-resin composite molded product, and manufacturing method of metal-resin composite molded product - Google Patents

Description

The present invention relates to a technology for joining metal members and thermoplastic resins.

By combining materials with different properties, such as electrically conductive materials such as metals and electrically insulating materials such as resins, parts that are lighter in weight, stronger, or more functional are used in various fields. For example, metal-resin composite molded products in which metal members and thermoplastic resins are bonded together are used in automobile interior parts such as console boxes around instrument panels, engine-related parts, interior parts, housings, interface connections, power terminals, etc. of electronic devices such as digital cameras and mobile phones.
Generally, bonding and screwing are known as methods for joining different materials such as metal and resin, but these methods are not preferable because they increase the number of steps and parts required. Therefore, various methods for joining metal and resin materials have been proposed.

For example, Patent Document 1 describes laser processing of the surface of a metal material in one scanning direction, followed by laser processing in another scanning direction crossing the first scanning direction, and joining a different material to this surface. Patent Document 2 describes how, when forming irregularities on the surface of a metal plate, the undercut rate of the irregularities is set within a specified range, thereby improving the joining strength when joining a resin molded product to this surface. Patent Document 3 describes a composite molded product of metal and resin in which crater-shaped depressions are formed in the metal by laser light or the like, and granular spatters are formed on the ridge-shaped protuberances where the metal surface has melted and scattered.

Patent No. 4020957 Patent Publication No. 2020-116806 Patent Publication No. 2013-71312

However, conventional methods for joining metal materials and resin materials are unable to ensure sufficient airtightness at the joint between the metal material and the resin material, and there is a demand for improvement in this regard.
SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to improve the airtightness of a joint when a metal member and a resin member are joined together.

A first aspect of the present invention is a metal-resin composite molded product in which a metal member and a thermoplastic resin are bonded by insert molding. In this metal-resin composite molded product, a high-energy beam is concentrically irradiated onto a surface portion of one side of the metal member that is bonded to the thermoplastic resin, and spherical clusters are formed over an area of 70% or more of the surface portion .

A second aspect of the present invention is a method for producing a metal-resin composite molded product in which a metal member and a thermoplastic resin are bonded together, in which a high-energy beam is concentrically irradiated onto a surface of a metal member to form spherical clusters over an area of 70% or more of the surface, and the metal member on which the spherical clusters have been formed on the surface and the thermoplastic resin are bonded together by insert molding .

According to one aspect of the present invention, it is possible to increase the airtightness of the joint when joining a metal member and a resin member.

1A to 1C are diagrams illustrating a method for processing a metal member according to an embodiment of the present invention. FIG. 2 is a diagram showing the shape of a test piece used in an air tightness test. FIG. 2 is a diagram showing the results of observation of the surface of a metal member of an example using a scanning electron microscope. FIG. 2 is a diagram showing the results of observation of the surface of a metal member of an example using a scanning electron microscope. FIG. 4 is a diagram showing the results of observation of the surface of a metal member of a comparative example using a scanning electron microscope. FIG. 4 is a diagram showing the results of observation of the surface of a metal member of a comparative example using a scanning electron microscope. FIG. 1 is a diagram showing a schematic configuration of a testing device for an airtightness test.

Hereinafter, a metal-resin composite molded product according to one embodiment of the present invention will be described.
In one embodiment, a metal resin composite molded product is formed by bonding a metal member and a thermoplastic resin. In this metal resin composite molded product, substantially spherical clusters are formed on one surface of the metal member that is bonded to the thermoplastic resin. The term "substantially spherical" does not limit the shape of each of the clusters to a sphere, but also includes ellipsoids, spheres or ellipsoids with a part missing, and the like.
The substantially spherical clusters can be formed by, for example, irradiating the surface of the metal member with a laser. As a result of intensive research, the inventors of the present application have found that it is possible to form spherical clusters on the metal surface by irradiating the surface of the metal member with a laser under predetermined irradiation conditions, thereby making it possible to improve the airtightness of the joint surface between the metal and the resin in a metal-resin composite molded product compared to the conventional method.
The shape of the metal-resin composite molded product is not particularly limited, and the present invention can be applied to metal-resin composite molded products of any shape.

The metal members contained in the metal-resin composite molded product are not limited to, but may be, for example, aluminum, copper, silver, gold, iron, titanium, nickel, magnesium, zinc, and alloys thereof such as carbon steel and stainless steel.
The surface of the metal material may be subjected to a surface treatment such as anodizing or painting. Aluminum, magnesium, copper, and titanium are preferable from the viewpoint of light weight and strength, and aluminum and copper are more preferable, and copper is particularly preferable, in applications requiring electrical conductivity such as terminals. Magnesium and titanium are preferable, and titanium is particularly preferable, in applications requiring rigidity in a thin wall.

The resin contained in the metal-resin composite molded product is preferably a thermoplastic resin that is easy to process by injection molding.
Examples of suitable thermoplastic resins include polyacetal (POM), polyamide (PA), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polycarbonate (PC), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyether ether ketone (PEEK), styrene-based resins, acrylic-based resins, and the like.

There is no limitation on the method for joining the metal member and the resin, but they can be joined by injection molding. For example, they can be joined by insert molding using a metal material as an insert member.

FIG. 1 is a schematic diagram showing a method for processing a metal member according to one embodiment.
As shown in Fig. 1, when a metal member is irradiated with a laser, the metal on the surface of the metal member is sublimated by the high energy beam of the laser, or the scattered liquid metal particles are solidified (re-adhered) and deposited to form spherical clusters. Here, when the laser output (energy per unit time) is low, the metal on the metal surface does not sublimate and the liquid metal particles do not scatter, so the laser output for forming spherical clusters is appropriately determined depending on the metal material used for the metal member.
In addition, the laser output and irradiation speed determine the energy given to the metal surface per unit area per unit time, so in addition to the laser output, the irradiation speed is also a factor in forming spherical clusters. The laser output and irradiation speed cause a localized temperature rise on the metal surface in an extremely short period of time, which results in the formation of spherical clusters.

In order to ensure sufficient airtightness when joined to resin, it is preferable to form spherical clusters over the entire surface of the joint surface of the metal member with the resin. To achieve this, it is advisable to set the laser scanning pitch smaller than the laser irradiation diameter.

In this disclosure, a "high energy beam" means a beam with energy per unit time high enough to form spherical clusters on the surface of a metal member.
The high energy beam is typically, but not necessarily, a laser, and may be a beam generated by an electron gun.

In one embodiment, a method for manufacturing a metal-resin composite molded product is a method in which a surface of a metal component is irradiated with a high-energy beam such as a laser to form substantially spherical clusters on the surface of the metal component, and the metal component with the substantially spherical clusters formed on its surface is melt-bonded to a thermoplastic resin.
By forming spherical clusters on the joint surface of the metal member with the resin, when the metal member and the thermoplastic resin are insert molded, the molten resin penetrates into the spherical clusters, increasing the adhesion between the metal and the resin during the molding stage. Therefore, the resulting metal-resin composite molded product achieves higher airtightness at the joint surface of the metal member than ever before.

The area in which the spherical clusters are formed on the surface of the metal member is preferably the entire surface of the joint surface of the metal member with the resin, but is not limited thereto. For example, if the spherical clusters are formed on most of the joint surface, for example, 70 to 80% or more of the joint surface, a sufficiently high level of airtightness can be ensured on the joint surface of the metal member.
For example, when the entire joint surface of the metal member with the resin is irradiated with the laser, if the scanning pitch of the laser is larger than the irradiation diameter of the laser, there will be areas on the joint surface that are not irradiated with the laser. Even in this case, if the areas on the joint surface that are not irradiated with the laser are relatively small, a sufficiently high level of airtightness is ensured on the joint surface of the metal member.

Examples of metal-resin composite molded products will be described below.
In the examples, a metal-resin composite molded product 10 (hereinafter referred to as "test piece 10") having a shape shown in FIG. 2 was prepared as a test piece.
As shown in Fig. 2, the test piece 10 is composed of a circular metal member 11 having an inner hole in the center, and a resin molded product 12 placed in the inner hole of the metal member 11. The metal member 11 has an outer diameter of φ50 mm, an inner hole diameter of φ20 mm, and a thickness of 1 mm. The resin molded product 12 has an outer diameter of φ30 mm and a thickness of 3 mm.

The following materials were used for the metal member 11 and the resin molded part 12.
Metal member 11: Aluminum A1050 (Example 1, Comparative Example 2), Aluminum A5052 (Example 2, Comparative Example 1), Copper C1100 (Example 3)
Thermoplastic resin 12: Polyphenylene sulfide (PPS) (Durafide (registered trademark) 1135MF1 (manufactured by Polyplastics Co., Ltd.)) (common to both the examples and comparative examples)

Before bonding to the resin molded product 12, a laser processing machine (ML-7350DL manufactured by Amada Weld Tech) was used to perform laser processing on the surface of the metal member 11 in the range of φ20 mm to φ26 mm (the bonding surface with the resin molded product 12). The laser irradiation conditions are as shown in Table 1 below.

In Table 1, the laser power and exposure speed determine the energy imparted to the metal surface per unit area per unit time.
For Examples 1 to 3 and Comparative Example 1, laser processing was performed by scanning the laser in a concentric pattern. However, as shown in Table 1, for Comparative Example 1, the laser output was lower than for Examples 1 to 3, and the pitch (30 μm) was larger than the pitch (10 μm) for Examples 1 to 3. The pitch is the distance between the concentric circles scanned with the laser. For Examples 1 to 3 and Comparative Example 1, the pitch was smaller than the irradiation diameter, and the entire joining surface was irradiated with the laser.
On the other hand, for Comparative Example 2, the laser processing was performed by scanning the laser in a lattice pattern. At that time, the pitch for scanning in a lattice pattern was set to 100 μm. In Comparative Example 2, since the pitch was larger than the irradiation diameter, there were parts of the joining surface that were not irradiated with the laser.

When the surface of the metal member 11 after the laser treatment was observed with a SEM (scanning electron microscope), it was confirmed that in Example 1 (see FIG. 3) and Example 2 (see FIG. 4), spherical clusters were generated all over the laser-treated surface of the metal member 11. The same was true for Example 3.
However, for Comparative Example 1 (see FIG. 5) and Comparative Example 2 (see FIG. 6), no spherical clusters were generated on the laser-treated surface. In FIG. 6 corresponding to Comparative Example 2, two grooves are observed as the laser-irradiated portion when the laser is irradiated in a lattice pattern, but no clusters were observed at the bottom of the grooves.

After the metal member 11 was subjected to laser processing, the metal member 11 was joined by insert molding using the metal material 11 as an insert member under the following conditions, thereby forming the test piece 10 shown in FIG.
・Injection molding machine: Sodick TR100EH
Cylinder temperature: 330°C
Mold temperature: 140°C
Injection speed: 70 mm/s
・Maintaining pressure: 70MPa

Next, an airtightness test was carried out on the molded test pieces (Examples 1 to 3, Comparative Examples 1 and 2). The configuration of a test device for the airtightness test (helium leak test, vacuum method) is shown in FIG.
As shown in Fig. 7, the jig 2 and the metal-resin composite molded product 10 are placed in a chamber 3 that is sealed from the outside. The jig 2 has a rectangular parallelepiped shape with a bottom, and by placing the test piece 10 on the top, the inside of the jig 2 is sealed from the rest of the chamber 3. With the valve 6 in an open state, the inside of the jig 2 is evacuated by the vacuum pump 5, and then with the valve 6 in a closed state, the chamber 3 is filled with helium gas by the helium cylinder 4. Helium gas leaking from the joint of the test piece 10 in the chamber 3 is detected by the helium detector 7. The control device 8 displays the detection result of the helium gas.
As the helium detector 7, a helium leak tester G-FINE manufactured by Cosmo Instruments Co., Ltd. and an L300i manufactured by Inficon Co., Ltd. were used.

The helium pressure in the chamber 3 was set to 400 kPa, and the vacuum pressure in the jig 2 was set to 100 kPa. If the airtightness of the joint between the metal member 11 and the resin molded product 12 of the test piece 10 is low, the helium gas in the chamber 3 flows into the jig 2 and is detected by the helium detector 7. In this test, if the helium detected by the helium detector 7 was 1.0×10 ^-7 Pa·m ³ /s or more, the airtightness was determined to be NG, and if it was less than 1.0×10 ^-7 Pa·m ³ /s, the airtightness was determined to be OK.

Table 1 shows the results of the airtightness test on the test pieces according to Examples 1 to 3 and Comparative Examples 1 and 2.

As shown in Table 1, it was confirmed that the test pieces of Examples 1 to 3, in which spherical clusters were formed on the joint surface between the metal member and the thermoplastic resin, had higher airtightness at the joint between the metal member and the resin than the test pieces of Comparative Examples 1 and 2, in which no clusters were formed.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments. Furthermore, various improvements and modifications can be made to the above embodiments without departing from the spirit of the present invention.

Reference Signs List 2: Jig 3: Chamber 4: Helium cylinder 5: Vacuum pump 6: Valve 7: Helium detector 8: Control device 10: Metal-resin composite molded product 11: Metal member 12: Resin molded product

Claims (2)

A metal resin composite molded product in which a metal member and a thermoplastic resin are bonded,
A surface portion of one surface of a metal member that is joined to a thermoplastic resin is concentrically irradiated with a high-energy beam, whereby spherical clusters are formed in an area of 70% or more of the surface portion .
A metal-resin composite molded product joined by insert molding. A method for producing a metal resin composite molded product in which a metal member and a thermoplastic resin are bonded, comprising the steps of:
A high-energy beam is concentrically irradiated onto a surface of a metal member to form spherical clusters over an area of 70% or more of the surface;
the metal member having the spherical clusters formed on its surface and a thermoplastic resin are joined by insert molding ;
A manufacturing method for metal-resin composite molded products.