JP7780558B2 - Method for molding metal-resin composite material, metal-resin composite part and method for manufacturing the same - Google Patents

Description

This disclosure relates to a method for molding metal-resin composite materials, as well as a metal-resin composite part and a method for manufacturing the same.

In recent years, growing concern about environmental issues has led to the widespread use of environmentally friendly vehicles equipped with secondary batteries, such as electric vehicles and hybrid vehicles. Many of these environmentally friendly vehicles use a system in which the direct current generated by the onboard secondary battery is converted to alternating current via an inverter, after which the necessary power is supplied to an AC motor to generate driving force. As a result, electromagnetic waves are generated due to the inverter's switching operation, etc. Because electromagnetic waves can interfere with on-board sensors, a countermeasure has been taken to shield electromagnetic waves by housing the inverter, or the inverter together with the battery and motor, etc., in a housing made of aluminum plate material with a specified coating on the surface (Patent Document 1).

Japanese Patent Application Laid-Open No. 2003-285002

In recent years, materials used for electromagnetic wave shielding have been required to be lightweight and to be able to be formed into complex shapes (particularly, to be able to be formed into molds having complex shapes). However, the aluminum sheet material described in Patent Document 1 cannot be said to fully meet these requirements.
On the other hand, methods for satisfying the above requirements include a method using an Al-deposited film in which aluminum is vapor-deposited on a resin film, and a method of applying electroless plating to a material with good formability. However, although the method using an Al-deposited film is inexpensive and has good formability, the vapor-deposited Al layer has a small thickness and lower conductivity than copper foil, etc., resulting in an insufficient electromagnetic wave shielding effect. In addition, the method of applying electroless plating to a material with good formability has a problem of being expensive and also of being difficult to increase the thickness of the plated layer, resulting in an insufficient electromagnetic wave shielding effect.

Therefore, the inventors focused on metal-resin composite materials in which metal layers and resin layers are laminated, and attempted to solve the above-mentioned requirements while ensuring the electromagnetic wave shielding effect by optimizing the configurations of the metal layers and resin layers.
However, although metal-resin composite materials have a good electromagnetic wave shielding effect, there is a problem that springback is likely to occur in the bent portion (flange portion) during molding (for example, bulging or drawing), making it difficult to fully obtain the desired dimensional accuracy.

The embodiments of the present invention have been made to solve the above problems, and have an object to provide a method for molding a metal-resin composite material that can suppress springback.
Another object of the embodiments of the present invention is to provide a metal-resin composite part with high dimensional accuracy and a method for manufacturing the same.

The inventors conducted extensive research to solve the above problems. Based on the finding that the layer structure of a metal-resin composite material and the direction in which pressing force is applied during molding are related to the occurrence of springback, they discovered that applying pressing force in a specific direction during molding of a metal-resin composite material with a specific layer structure can improve the springback suppression effect, leading to the completion of an embodiment of the present invention.

That is, an embodiment of the present invention is a method for molding a metal resin composite material having a laminate structure in which metal layers and resin layers are alternately laminated, and the laminate structure is asymmetric,
the resin layer is a PET resin layer,
The metal-resin composite material is divided into an a-section and a b-section at a position halfway through the entire layer thickness, and the total layer thickness of the resin layers present in the a-section is defined as Tra, the total layer thickness of the metal layers present in the a-section is defined as Tma, the total layer thickness of the resin layers present in the b-section is defined as Trb, and the total layer thickness of the metal layers present in the b-section is defined as Tmb,
When Tma/Tra>Tmb/Trb, molding is performed by placing the part a side on the surface to which the pressing force is applied,
When Tma/Tra<Tmb/Trb, molding is performed by placing the part b on the surface to which the pressing force is applied,
This is a molding method for a metal-resin composite material, in which, when Tma/Tra = Tmb/Trb, the side of part a or part b on which the metal layer is located as the surface layer or the side closest to the metal layer is placed on the surface to which the pressing force is applied, and molding is performed.
Further, an embodiment of the present invention is a method for molding a metal resin composite material having a laminate structure in which metal layers and resin layers are alternately laminated, wherein the laminate structure is asymmetric,
The metal-resin composite material has two or more of the metal layers,
The metal-resin composite material is divided into an a-section and a b-section at a position halfway through the entire layer thickness, and the total layer thickness of the resin layers present in the a-section is defined as Tra, the total layer thickness of the metal layers present in the a-section is defined as Tma, the total layer thickness of the resin layers present in the b-section is defined as Trb, and the total layer thickness of the metal layers present in the b-section is defined as Tmb,
When Tma/Tra>Tmb/Trb, molding is performed by placing the part a side on the surface to which the pressing force is applied,
When Tma/Tra<Tmb/Trb, molding is performed by placing the part b on the surface to which the pressing force is applied,
This is a molding method for a metal-resin composite material, in which, when Tma/Tra = Tmb/Trb, the side of part a or part b on which the metal layer is located as the surface layer or the side closest to the metal layer is placed on the surface to which the pressing force is applied, and molding is performed.

Another embodiment of the present invention is a method for manufacturing a metal-resin composite part, which includes the above-mentioned method for molding a metal-resin composite material.

Furthermore, an embodiment of the present invention is a metal resin composite part formed from a metal resin composite material having a laminate structure in which metal layers and resin layers are alternately laminated, and the laminate structure is asymmetric,
the resin layer is a PET resin layer,
The metal-resin composite material is divided into an a-section and a b-section at a position halfway through the entire layer thickness, and the total layer thickness of the resin layers present in the a-section is defined as Tra, the total layer thickness of the metal layers present in the a-section is defined as Tma, the total layer thickness of the resin layers present in the b-section is defined as Trb, and the total layer thickness of the metal layers present in the b-section is defined as Tmb,
When Tma/Tra>Tmb/Trb, the a-part side is disposed on the surface to which the pressing force is applied,
When Tma/Tra<Tmb/Trb, the portion b is disposed on the surface to which the pressing force is applied,
When Tma/Tra = Tmb/Trb, the side of part a or part b on which the metal layer is located as a surface layer or the side closest to the metal layer is arranged on the surface to which the pressing force is applied, which is a metal-resin composite part.
Further, an embodiment of the present invention is a metal resin composite part formed from a metal resin composite material having a laminate structure in which metal layers and resin layers are alternately laminated, and the laminate structure is asymmetric,
The metal-resin composite material has two or more of the metal layers,
The metal-resin composite material is divided into an a-section and a b-section at a position halfway through the entire layer thickness, and the total layer thickness of the resin layers present in the a-section is defined as Tra, the total layer thickness of the metal layers present in the a-section is defined as Tma, the total layer thickness of the resin layers present in the b-section is defined as Trb, and the total layer thickness of the metal layers present in the b-section is defined as Tmb,
When Tma/Tra>Tmb/Trb, the a-part side is disposed on the surface to which the pressing force is applied,
When Tma/Tra<Tmb/Trb, the portion b is disposed on the surface to which the pressing force is applied,
When Tma/Tra = Tmb/Trb, the side of part a or part b on which the metal layer is located as a surface layer or the side closest to the metal layer is arranged on the surface to which the pressing force is applied, which is a metal-resin composite part.

According to an embodiment of the present invention, a method for molding a metal-resin composite material capable of suppressing springback can be provided.
Furthermore, according to the embodiment of the present invention, it is possible to provide a metal-resin composite part with high dimensional accuracy and a method for manufacturing the same.

FIG. 1 is a cross-sectional view of a metal resin composite material having a two-layer structure of a metal layer/a resin layer. FIG. 1 is a cross-sectional view of a metal resin composite material having a three-layer structure of metal layer/resin layer/metal layer. FIG. 1 is a cross-sectional view of a metal resin composite material having a four-layer structure of metal layer/resin layer/metal layer/resin layer. 10A and 10B are diagrams for explaining a method of applying a pressing force F in drawing. 1 is a photograph of the molded articles molded in Example 1 and Comparative Example 1.

The following describes in detail preferred embodiments of the present invention with reference to the drawings, but the present invention should not be construed as being limited to these embodiments. Various modifications and improvements can be made based on the knowledge of those skilled in the art, provided they do not deviate from the gist of the present invention. The multiple components disclosed in this embodiment can be combined appropriately to form various inventions. For example, some components may be deleted from all of the components shown in this embodiment, or components from different embodiments may be combined appropriately.

In the method for molding a metal resin composite material according to an embodiment of the present invention, molding is performed by applying a pressing force from a specific direction depending on the type of layered structure of the metal resin composite material.
A metal-resin composite material has a laminated structure in which metal layers and resin layers are alternately laminated, and has an electromagnetic wave shielding effect, so it can be used as an electromagnetic wave shielding material.

The number of layers in the laminated structure of the metal-resin composite material is not particularly limited as long as it is 2 or more, but is preferably 2 to 15 layers, more preferably 2 to 10 layers, and even more preferably 2 to 8 layers. Examples of the laminated structure include a two-layer structure of metal layer/resin layer, a three-layer structure of resin layer/metal layer/resin layer or metal layer/resin layer/metal layer, and a four-layer structure of resin layer/metal layer/resin layer/metal layer or metal layer/resin layer/metal layer/resin layer.
The laminate structure of a metal-resin composite material is asymmetric. When the number of layers of the metal-resin composite material is even, the laminate structure is asymmetric. On the other hand, when the number of layers of the metal-resin composite material is odd (excluding 1), the laminate structure can be asymmetric or symmetric. An example of a symmetric laminate structure is when the first and third layers of a three-layer structure have the same thickness. Another example of an asymmetric laminate structure is when the first and third layers of a three-layer structure have different thicknesses.
Furthermore, the laminated structure of the metal-resin composite material preferably has two or more metal layers, which increases the number of surfaces that reflect electromagnetic waves, thereby improving the electromagnetic wave shielding effect.

The method for molding a metal-resin composite material according to an embodiment of the present invention is carried out as follows.
In a laminated structure of a metal-resin composite material, the metal-resin composite material is divided into two parts, part a and part b, at a position halfway through the total layer thickness. The total layer thickness of the resin layers present in part a is designated Tra, the total layer thickness of the metal layers present in part a is designated Tma, the total layer thickness of the resin layers present in part b is designated Trb, and the total layer thickness of the metal layers present in part b is designated Tmb. The direction of application of pressing force is then determined according to each of the following cases (1) to (3), and molding is performed.
(1) When Tma/Tra>Tmb/Trb, molding is performed with the part a side positioned on the surface to which the pressing force is applied.
(2) When Tma/Tra<Tmb/Trb, molding is performed with the part b positioned on the surface to which the pressing force is applied.
(3) When Tma/Tra=Tmb/Trb, the side of part a or part b on which the metal layer is located on the surface or the side closest to the metal layer is placed on the surface to which the pressing force is applied, and molding is performed.
By performing forming while applying a pressing force as described above, it is possible to suppress the occurrence of springback.

Here, a cross-sectional view of a metal-resin composite material corresponding to case (1) is shown in FIG.
Fig. 1 is a cross-sectional view of a metal resin composite material having a two-layer structure of a metal layer 10/resin layer 20. When the metal resin composite material is divided into parts a and b at a position halfway through the total layer thickness, Tra, Tma, and Trb can be determined as shown in Fig. 1. Note that in the metal resin composite material of Fig. 1, Tmb is zero due to the two-layer structure, but if the metal resin composite material has a laminated structure of three or more layers, Tmb can be set to be greater than zero.
The metal-resin composite material of FIG. 1 is molded by placing the portion a on the surface to which the pressing force F is applied, in order to satisfy the relationship Tma/Tra>Tmb/Trb.

Next, a cross-sectional view of a metal-resin composite material corresponding to case (2) is shown in FIG.
Fig. 2 is a cross-sectional view of a metal resin composite material having a three-layer structure of metal layer 10/resin layer 20/metal layer 10. When the metal resin composite material is divided into portions a and b at a position halfway through the total layer thickness, Tra, Tma, Tmb, and Trb can be determined as shown in Fig. 2. In the metal resin composite material of Fig. 2, the two metal layers 10 have different thicknesses, and the thickness of the metal layer 10 in portion b is set larger than the thickness of the metal layer 10 in portion a.
The metal-resin composite material of FIG. 2 is molded by placing the portion b on the surface to which the pressing force F is applied, in order to satisfy the relationship Tma/Tra<Tmb/Trb.

Next, a cross-sectional view of a metal-resin composite material corresponding to the case (3) is shown in FIG.
Fig. 3 is a cross-sectional view of a metal resin composite material having a four-layer structure of metal layer 10/resin layer 20/metal layer 10/resin layer 20. When the metal resin composite material is divided into portions a and b at a position halfway through the total layer thickness, Tra, Tma, Tmb, and Trb can be determined as shown in Fig. 3. In the metal resin composite material of Fig. 3, the two metal layers 10 and the two resin layers 20 have the same thickness.
The metal-resin composite material of FIG. 3 satisfies the relationship Tma/Tra=Tmb/Trb, and the metal layer 10 is located on the surface of the portion a. Therefore, molding is performed by placing the portion a on the surface to which the pressing force F is applied.

The method for forming the metal-resin composite material is not particularly limited as long as it is a method that can apply a pressing force F to a predetermined surface, and any method known in the technical field can be used. Examples of forming methods include drawing, stretching, bending, and air-pressure forming. Among these, drawing is preferred because it has good processability into complex shapes. When the forming method is drawing, the pressing force F is applied by a punch.
Here, as an example, a method of applying a pressing force F in drawing will be described with reference to FIG. 4 . When the surface to which the pressing force F is applied is the portion a side of the metal-resin composite material, the portion a side of the metal-resin composite material is placed on the surface that comes into contact with the punch 30 that applies the pressing force F. Then, by pressing the punch 30 in the thickness direction of the metal-resin composite material to form it, a molded body (metal-resin composite part) having a predetermined shape can be obtained. Although not shown, the metal-resin composite material is placed in a die, and the peripheral portion is fixed by a blank holder, and then formed by the punch 30.
Furthermore, molding of the metal-resin composite material can be carried out at room temperature or in a warm state, but even when molding is carried out at room temperature, the occurrence of springback can be suppressed.
The magnitude of the pressing force F is not particularly limited and may be adjusted appropriately depending on the molding method used, the thickness of the metal-resin composite material, and the like.

It is preferable that the metal resin composite material has a metal layer 10 disposed on the surface to which the pressing force F is applied. With this configuration, when the metal resin composite material is molded to produce an electromagnetic wave shielding housing, the inner surface of the electromagnetic wave shielding housing becomes the metal layer 10, making it easy to ground.

The material for the metal layer 10 is not particularly limited, and various metals can be used. Among these, metals with excellent conductivity can be used to enhance the electromagnetic wave shielding effect against AC magnetic fields and AC electric fields. Specifically, the conductivity of the metal used for the metal layer 10 is preferably 1.0×10 ⁶ S/m or more (value at 20°C, the same applies below), more preferably 10.0×10 ⁶ S/m or more, even more preferably 30.0×10 ⁶ S/m or more, and most preferably 50.0×10 ⁶ S/m or more. Examples of such metals with excellent conductivity include iron with a conductivity of approximately 9.9×10 ⁶ S/m, nickel with a conductivity of approximately 14.5×10 ⁶ S/m, aluminum with a conductivity of approximately 39.6×10 ⁶ S/m, copper with a conductivity of approximately 58.0×10 ⁶ S/m, and silver with a conductivity of approximately 61.4×10 ⁶ S/m. Among these, aluminum or copper is preferable in terms of practicality, taking into consideration both conductivity and cost. Also, an alloy of the above-mentioned metals may be used for the metal layer 10.
When a plurality of metal layers 10 are present in the metal-resin composite material, the plurality of metal layers 10 may be the same or different.

The surface of the metal layer 10 may be formed with various surface treatment layers for the purpose of improving adhesion promotion, environmental resistance, heat resistance, rust prevention, and the like.
For example, in order to improve the environmental resistance and heat resistance required when the metal surface is the outermost layer, an Au plating layer, an Ag plating layer, an Sn plating layer, a Ni plating layer, a Zn plating layer, an Sn alloy plating layer (such as an Sn—Ag layer, an Sn—Ni layer, or an Sn—Cu layer), a chromate treatment layer, or the like may be formed on the surface of the metal layer 10. These treatment layers may be single or multiple. Furthermore, among these treatment layers, an Sn plating layer or an Sn alloy plating layer is preferred from the standpoint of cost.
Furthermore, in order to improve the adhesion between the metal layer 10 and the resin layer 20, a chromate-treated layer, a roughened layer, a Ni-plated layer, or the like may be formed on the surface of the metal layer 10. These treatment layers may be formed singly or in combination. Among these treatment layers, the roughened layer is preferred because it is highly effective in improving adhesion.
Furthermore, in order to improve the electromagnetic wave shielding effect against DC magnetic fields, a layer with high relative magnetic permeability may be provided on the surface of the metal layer 10. Examples of the layer with high relative magnetic permeability include an Fe—Ni alloy plating layer and a Ni plating layer.

When a copper foil layer is used as the metal layer 10, a copper foil with high purity is preferred from the viewpoint of improving the electromagnetic wave shielding effect. The purity of the copper foil used for the copper foil layer is preferably 99.5% by mass or more, more preferably 99.8% by mass or more.
As the copper foil, rolled copper foil, electrolytic copper foil, metallized copper foil, etc. can be used, but rolled copper foil is preferred because of its excellent flexibility and formability. When alloy elements are added to copper foil to form a copper alloy foil, the total content of these elements and unavoidable impurities should be less than 0.5 mass%. In particular, it is preferable for the copper foil to contain a total of 200 to 2000 mass ppm of at least one element selected from the group consisting of Sn, Mn, Cr, Zn, Zr, Mg, Ni, Si, and Ag, because this improves elongation compared to pure copper foil of the same thickness.

The thickness of the metal layer 10 is not particularly limited, but is preferably 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, even more preferably 25 μm or more, and particularly preferably 30 μm or more per layer. By making the thickness of the metal layer 10 10 μm or more, it is possible to ensure a sufficient electromagnetic wave shielding effect. Furthermore, the thickness of the metal layer 10 is preferably 100 μm or less, more preferably 50 μm or less, even more preferably 45 μm or less, and particularly preferably 40 μm or less per layer. By making the thickness of the metal layer 10 100 μm or less, it is possible to suppress a decrease in moldability.
When a plurality of metal layers 10 are present in the metal-resin composite material, the thicknesses of the plurality of metal layers 10 may be the same or different.

The material of the resin layer 20 is not particularly limited, and various resins can be used. Examples of resins include PET (polyethylene terephthalate) resin, PEN (polyethylene naphthalate) resin, PI (polyimide) resin, PC (polycarbonate) resin, PE (polyethylene) resin, and PP (polypropylene) resin. Since these resins all have relatively large springback, when these resins are used and the molding method according to the present disclosure is applied, springback can be effectively suppressed. Furthermore, among the above-mentioned resins, PET resin is preferable because it is inexpensive.
When a plurality of resin layers 20 are present in the metal-resin composite material, the plurality of resin layers 20 may be the same or different.

The thickness of the resin layer 20 is not particularly limited, but is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 30 μm or more, and particularly preferably 40 μm or more per layer. By making the thickness of the resin layer 20 10 μm or more, the strength of the housing can be ensured when manufacturing a housing from the metal-resin composite material. Furthermore, the thickness of the resin layer 20 is preferably 300 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less per layer. Furthermore, by making the thickness of the resin layer 20 300 μm or less, a decrease in moldability can be suppressed.
When a plurality of resin layers 20 are present in the metal-resin composite material, the thicknesses of the plurality of resin layers 20 may be the same or different, but are preferably the same.

The resin layer 20 can be formed using a resin film, but may also be formed by directly applying a resin material onto the metal layer 10 and curing it.
When a resin film is used as the resin layer 20, the method for bonding the metal layer 10 and the resin film is not particularly limited, and any method known in the art can be used. For example, the metal layer 10 and the resin film may be bonded by thermocompression bonding, or the metal layer 10 and the resin film may be bonded using an adhesive. However, since resin films such as PET resin films are difficult to bond to the metal layer 10 by thermocompression bonding, it is preferable to bond them using an adhesive.

The adhesive is not particularly limited, and known adhesives such as thermoplastic adhesives and thermosetting adhesives can be used. Among them, thermosetting adhesives are chemically stable, and therefore can make the adhesive portion less susceptible to changes over time.
Here, the thermoplastic adhesive refers to an adhesive whose main component is a thermoplastic resin that softens when heated and hardens when cooled. Examples of the thermoplastic resin include, but are not limited to, polyvinyl acetate, vinyl acetate-vinyl chloride copolymer, polyvinyl butyral, α-olefin resin, cellulose resin, acrylic resin, vinyl chloride resin, and polyvinyl acetal. These may be used alone or in combination of two or more.
Furthermore, a thermosetting adhesive refers to an adhesive whose main component is a thermosetting resin that hardens when heated. Examples of thermosetting resins include, but are not limited to, urea resin, melamine resin, phenolic resin, resorcinol resin, epoxy resin, structural acrylic resin, polyester resin, and polyurethane resin. These may be used alone or in combination of two or more.

The total layer thickness of the metal-resin composite material is not particularly limited, but is preferably 110 to 800 μm, more preferably 150 to 700 μm, even more preferably 200 to 600 μm, and particularly preferably 250 to 500 μm. By making the total layer thickness of the metal-resin composite material 110 μm or more, the strength of the housing can be ensured when a housing is made from the metal-resin composite material. Furthermore, by making the total layer thickness of the metal-resin composite material 800 μm or less, deterioration in moldability can be suppressed.

The method for molding a metal resin composite material according to an embodiment of the present invention can be used in a method for manufacturing a metal resin composite part. Therefore, the method for manufacturing a metal resin composite part includes the method for molding a metal resin composite material according to an embodiment of the present invention.
Here, in this specification, the term "metal-resin composite part" refers to a part obtained by molding a metal-resin composite material into a predetermined shape. Examples of metal-resin composite parts include, but are not limited to, various parts that require electromagnetic wave shielding properties. Among these, the metal-resin composite part is preferably an electromagnetic wave shielding housing.

The metal-resin composite part according to an embodiment of the present invention manufactured as described above has a laminated structure in which metal layers 10 and resin layers 20 are alternately stacked, and is formed from a metal-resin composite material in which the laminated structure is asymmetric.
Furthermore, when the metal resin composite part according to an embodiment of the present invention is divided into parts a and b at a position halfway through the total layer thickness of the metal resin composite material, and the total layer thickness of the resin layers 20 present in part a is defined as Tra, the total layer thickness of the metal layers 10 present in part a is defined as Tma, the total layer thickness of the resin layers 20 present in part b is defined as Trb, and the total layer thickness of the metal layers 10 present in part b is defined as Tmb, the metal resin composite part has any one of the following structures (1) to (3):
(1) When Tma/Tra>Tmb/Trb, the part a side is placed on the surface to which the pressing force F is applied.
(2) When Tma/Tra<Tmb/Trb, the portion b is placed on the surface to which the pressing force F is applied.
(3) When Tma/Tra = Tmb/Trb, the side of part a or part b on which metal layer 10 is located on the surface or the side closest to metal layer 10 is placed on the surface to which pressing force F is applied.
By using the above-described structure, it is possible to suppress the occurrence of springback during molding of the metal-resin composite material, thereby improving the dimensional accuracy of the metal-resin composite part.

Details about the metal-resin composite material that forms the metal-resin composite part have been described above, so further explanation will be omitted.

The present invention will be explained in more detail below using examples, but the present invention is not limited to these examples in any way.

<Preparation of Metal-Resin Composite Material A>
A two-layer metal-resin composite material A (hereinafter, this laminate structure may be abbreviated as "Cu/PET") was prepared by laminating a rolled copper foil (thickness 17 μm) having a roughened surface layer formed thereon and a PET resin film (thickness 100 μm). A thermosetting adhesive was used to bond the rolled copper foil and the PET resin film. In this metal-resin composite material A, the rolled copper foil side is designated as part a, and the PET resin film side is designated as part b.

<Preparation of Metal-Resin Composite Material B>
A two-layer metal-resin composite material B (hereinafter, this laminate structure may be abbreviated as "Cu/PET") was prepared by laminating a rolled copper foil (thickness 18 μm) having a roughened surface layer formed thereon and a PET resin film (thickness 100 μm). A thermosetting adhesive was used to bond the rolled copper foil and the PET resin film. In this metal-resin composite material B, the rolled copper foil side is designated as part a, and the PET resin film side is designated as part b.

<Preparation of Metal-Resin Composite Material C>
A two-layer metal-resin composite material C (hereinafter, this laminate structure may be abbreviated as "Cu/PET") was prepared by laminating a rolled copper foil (thickness: 35 μm) having a roughened surface layer formed thereon and a PET resin film (thickness: 100 μm). A thermosetting adhesive was used to bond the rolled copper foil and the PET resin film. In this metal-resin composite material C, the rolled copper foil side is designated as part a, and the PET resin film side is designated as part b.

<Preparation of Metal-Resin Composite Material D>
A six-layer metal-resin composite material D (hereinafter, this laminate structure may be abbreviated as "Cu/PET/Cu/PET/Cu/PET") was produced by alternately laminating three rolled copper foils (18 μm thick) with roughened layers formed on their surfaces and three PET resin films (100 μm thick). A thermosetting adhesive was used to bond the rolled copper foils and the PET resin films. In this metal-resin composite material D, the rolled copper foil side exposed on the surface is referred to as part a, and the PET resin film side exposed on the surface is referred to as part b.

<Preparation of Metal-Resin Composite Material E>
A six-layer metal-resin composite material E (hereinafter, this laminate structure may be abbreviated as "Cu/PET/Cu/PET/Cu/PET") was produced by alternately laminating three rolled copper foils (18 μm thick) with roughened layers formed on their surfaces and three PET resin films (50 μm thick). A thermosetting adhesive was used to bond the rolled copper foils and the PET resin films. In this metal-resin composite material E, the rolled copper foil side exposed on the surface is referred to as part a, and the PET resin film side exposed on the surface is referred to as part b.

<Preparation of Metal-Resin Composite Material F>
A four-layer metal-resin composite material F (hereinafter, this laminate structure may be abbreviated as "Cu/PET/Cu/PET") was produced by alternately laminating two rolled copper foils (35 μm thick) with roughened treatment layers formed on their surfaces and two PET resin films (50 μm thick). A thermosetting adhesive was used to bond the rolled copper foils and the PET resin films. In this metal-resin composite material F, the rolled copper foil side exposed on the surface is referred to as part a, and the PET resin film side exposed on the surface is referred to as part b.

Table 1 shows the values of Tma/Tra and Tmb/Trb calculated from the laminate structures of the metal-resin composite materials A to F prepared as described above.
Furthermore, the metal-resin composite materials A to F were used to carry out the following evaluations.

<Moldability>
The above metal resin composite materials A to F were subjected to drawing to form a rectangular tube with a flange at a 90° angle. The drawing was performed twice for each of the metal resin composite materials A to F, with the side of part a and the side of part b positioned on the surface to which the pressing force of the punch was applied.
In this evaluation, when comparing the results of molding processability using molding methods using the same type of metal-resin composite material, molding methods that resulted in smaller springback of the flange portion were represented by ○, and molding methods that resulted in larger springback were represented by ×. For example, as shown in Figure 5, the molded product of Example 1 (metal-resin composite part) molded with metal-resin composite material A, in which the a-side was positioned on the surface on which the pressing force was applied by the punch, clearly had smaller springback of the flange portion than the molded product of Comparative Example 1, in which the b-side was positioned on the surface on which the pressing force was applied. Therefore, the processability of the molded product of Example 1 was evaluated as ○, and the processability of the molded product of Comparative Example 1 was evaluated as ×.

<W-bend test>
Test pieces measuring 10 mm wide and 60 mm long were cut out from the above metal-resin composite materials A to F. These test pieces were subjected to a 90° W-bend at room temperature with a processing speed of 900 mm/min, a bending radius of 0 mm, a load of 2 kN, and a holding time of 2 seconds at the bottom dead center. The angle of the bent portion (center portion) that forms the peak of the W-bent test piece was measured, and the deviation from 90° (90° - measurement angle), i.e., the magnitude of springback, was determined.
The results of the above evaluations are shown in Table 1.

As shown in Table 1, the metal-resin composite material A had a relationship of Tma/Tra>Tmb/Trb. Therefore, compared with the case where the metal-resin composite material A was molded by placing the part a side on the pressing force application surface (Comparative Example 1), the case where the metal-resin composite material A was molded by placing the part b side on the pressing force application surface (Example 1) had better moldability and results in the W-bend test.
For metal-resin composite material B, Tma/Tra was greater than Tmb/Trb, and therefore, when molding was performed with part a placed on the surface to which the pressing force was applied (Example 2), the molding processability and the results of the W-bend test were better than when molding was performed with part b placed on the surface to which the pressing force was applied (Comparative Example 2).
Since metal-resin composite material C had Tma/Tra>Tmb/Trb, the moldability and the results of the W-bend test were better when it was molded with part a placed on the surface to which the pressing force was applied (Example 3) than when it was molded with part b placed on the surface to which the pressing force was applied (Comparative Example 3).

Since metal-resin composite material D had Tma/Tra>Tmb/Trb, the moldability and the results of the W-bend test were better when molded with part a placed on the surface to which the pressing force was applied (Example 4) than when molded with part b placed on the surface to which the pressing force was applied (Comparative Example 4).
Since the metal-resin composite material E had Tma/Tra>Tmb/Trb, the moldability and the results of the W-bend test were better when the metal-resin composite material E was molded with the a-side portion positioned on the surface where the pressing force was applied (Example 5) than when the metal-resin composite material E was molded with the b-side portion positioned on the surface where the pressing force was applied (Comparative Example 5).
In the metal-resin composite material E, Tma/Tra = Tmb/Trb, and the metal layer was located on the surface of the a-section. Therefore, compared with the case where the b-section was placed on the pressing force application surface (Comparative Example 6), the case where the a-section was placed on the pressing force application surface (Example 6) exhibited better moldability and W-bend test results.

As can be seen from the above results, embodiments of the present invention can provide a molding method for metal-resin composite materials that can suppress springback. Furthermore, embodiments of the present invention can provide metal-resin composite parts with high dimensional accuracy and methods for manufacturing the same.

10 Metal layer 20 Resin layer 30 Punch

Claims (20)

A method for molding a metal resin composite material having a laminated structure in which metal layers and resin layers are alternately laminated, wherein the laminated structure is asymmetric, comprising:
the resin layer is a PET resin layer,
The metal-resin composite material is divided into an a-section and a b-section at a position halfway through the entire layer thickness, and the total layer thickness of the resin layers present in the a-section is defined as Tra, the total layer thickness of the metal layers present in the a-section is defined as Tma, the total layer thickness of the resin layers present in the b-section is defined as Trb, and the total layer thickness of the metal layers present in the b-section is defined as Tmb,
When Tma/Tra>Tmb/Trb, molding is performed by placing the part a side on the surface to which the pressing force is applied,
When Tma/Tra<Tmb/Trb, molding is performed by placing the part b on the surface to which the pressing force is applied,
A method for molding a metal-resin composite material, in which, when Tma/Tra = Tmb/Trb, the side to which a pressing force is applied is the side of the part a or the part b on which the metal layer is located as a surface layer or the side closest to the metal layer, and molding is performed. The method for molding a metal resin composite material according to claim 1 , wherein the metal resin composite material has two or more metal layers. A method for molding a metal resin composite material having a laminated structure in which metal layers and resin layers are alternately laminated, wherein the laminated structure is asymmetric, comprising:
The metal-resin composite material has two or more of the metal layers,
The metal-resin composite material is divided into an a-section and a b-section at a position halfway through the entire layer thickness, and the total layer thickness of the resin layers present in the a-section is defined as Tra, the total layer thickness of the metal layers present in the a-section is defined as Tma, the total layer thickness of the resin layers present in the b-section is defined as Trb, and the total layer thickness of the metal layers present in the b-section is defined as Tmb,
When Tma/Tra>Tmb/Trb, molding is performed by placing the part a side on the surface to which the pressing force is applied,
When Tma/Tra<Tmb/Trb, molding is performed by placing the part b on the surface to which the pressing force is applied,
A molding method for a metal-resin composite material, in which, when Tma/Tra = Tmb/Trb, the side to which a pressing force is applied is the side of the a part or the b part on which the metal layer is located as a surface layer or the side closest to the metal layer, and molding is performed. The method for molding a metal resin composite material according to any one of claims 1 to 3, wherein the molding is carried out at room temperature. The method for molding a metal resin composite material according to any one of claims 1 to 4 , wherein the molding is performed by drawing. The method for molding a metal resin composite material according to any one of claims 1 to 5 , wherein the metal layer is a copper foil layer. The method for molding a metal resin composite material according to any one of claims 1 to 6 , wherein the thickness of one of the metal layers is 10 to 50 µm. The method for molding a metal resin composite material according to any one of claims 1 to 7 , wherein the thickness of one of the resin layers is 20 to 200 µm. The method for molding a metal resin composite material according to any one of claims 1 to 8 , wherein the metal layer is disposed on a surface to which the pressing force is applied. The method for molding a metal resin composite material according to any one of claims 1 to 9 , wherein the metal layer and the resin layer are bonded together with an adhesive. A method for producing a metal-resin composite part, comprising the method for molding the metal-resin composite material according to any one of claims 1 to 10 . A metal-resin composite part formed from a metal-resin composite material having a laminate structure in which metal layers and resin layers are alternately laminated, the laminate structure being asymmetric,
the resin layer is a PET resin layer,
The metal-resin composite material is divided into an a-section and a b-section at a position halfway through the entire layer thickness, and the total layer thickness of the resin layers present in the a-section is defined as Tra, the total layer thickness of the metal layers present in the a-section is defined as Tma, the total layer thickness of the resin layers present in the b-section is defined as Trb, and the total layer thickness of the metal layers present in the b-section is defined as Tmb,
When Tma/Tra>Tmb/Trb, the a-part side is disposed on the surface to which the pressing force is applied,
When Tma/Tra<Tmb/Trb, the portion b is disposed on the surface to which the pressing force is applied,
A metal-resin composite part in which, when Tma/Tra = Tmb/Trb, the side of the a part or the b part on which the metal layer is located as a surface layer or the side closest to the metal layer is arranged on the surface to which the pressing force is applied. The metal-resin composite part according to claim 12 , wherein the metal-resin composite material has two or more metal layers. A metal-resin composite part formed from a metal-resin composite material having a laminate structure in which metal layers and resin layers are alternately laminated, the laminate structure being asymmetric,
The metal-resin composite material has two or more of the metal layers,
The metal-resin composite material is divided into an a-section and a b-section at a position halfway through the entire layer thickness, and the total layer thickness of the resin layers present in the a-section is defined as Tra, the total layer thickness of the metal layers present in the a-section is defined as Tma, the total layer thickness of the resin layers present in the b-section is defined as Trb, and the total layer thickness of the metal layers present in the b-section is defined as Tmb,
When Tma/Tra>Tmb/Trb, the a-part side is disposed on the surface to which the pressing force is applied,
When Tma/Tra<Tmb/Trb, the portion b is disposed on the surface to which the pressing force is applied,
A metal-resin composite part in which, when Tma/Tra = Tmb/Trb, the side of the a part or the b part on which the metal layer is located as a surface layer or the side closest to the metal layer is arranged on the surface to which the pressing force is applied. The metal-resin composite part according to any one of claims 12 to 14 , wherein the metal layer is a copper foil layer. The metal-resin composite part according to any one of claims 12 to 15 , wherein the thickness of one of the metal layers is 10 to 50 µm. The metal-resin composite part according to any one of claims 12 to 16 , wherein the thickness of one of the resin layers is 20 to 200 µm. The metal-resin composite part according to any one of claims 12 to 17 , wherein the metal layer is disposed on the surface to which the pressing force is applied. The metal-resin composite part according to any one of claims 12 to 18 , wherein the metal layer and the resin layer are bonded together with an adhesive. The metal-resin composite part according to any one of claims 12 to 19 , which is an electromagnetic wave shielding housing.