JP2024008799A - Joining method - Google Patents

Abstract

To provide a technique that can easily join a metal and a resin.SOLUTION: A joining method for joining a metal base material and a resin base material includes: a process of applying a polymer solution containing a water-soluble polymer having functional groups to a surface of the metal base material to form a chemical bonding layer that adheres to the surface of the metal base material through covalent bonding between the water-soluble polymer and groups present on the surface of the metal base material; and a process of melting the resin base material and fusing it to the chemical bonding layer adhering to the metal base material.SELECTED DRAWING: Figure 2

Description

The present invention relates to a joining method for joining metal and resin.

Conventionally, various techniques have been proposed for joining methods for joining metal and resin. For example, in Patent Document 1 below, fine protrusions are formed on the surface of a metal base material by so-called laser cladding, and a resin base material placed on the protrusions is melted by laser irradiation to create an anchor effect. discloses a method for joining resin base materials.

International Publication WO2019/198591

However, the technique of Patent Document 1 described above may require large-scale preparation and equipment for laser cladding, and cannot be said to be easy. Furthermore, in the technique of Patent Document 1 mentioned above, when joining molded plastic base materials, it is not possible to apply a pressing force to the plastic base materials to exhibit an anchor effect, and the plastic base material and the metal base material cannot be bonded. There was also the possibility that voids would form between the materials and the joint strength would decrease.

An object of the present application is to provide a technology that can bond metal and resin in a simpler way than conventional bonding using anchor effects or adhesives using organic solvents.

The present invention can be realized as the following forms.

[First form] The joining method of the first form includes a first step of performing at least one of degreasing and cleaning and surface modification by plasma treatment on the joining surface of the metal material, and heating the bonding surface of the metal material after the first step. A second step of preparing a polymer solution containing a resin component that forms a chemical bond with the bonding surface of the metal material and coating it on the bonding surface to form a chemical bonding layer; and heating to form a chemical bonding layer. a third step of preparing a resin material containing resin components to be melt-mixed and bonded; and laminating the resin material prepared in the third step on the polymer solution applied in the second step. The metal material and the resin material are joined by heating and pressing or by injection molding the resin material.
According to the joining method of the first embodiment, joining can be easily performed at low cost without using large-scale equipment such as a laser.

[Second Embodiment] The polymer solution used in the bonding method of the first embodiment may contain an inorganic powder that melts at the temperature during bonding.
By including inorganic powder in the polymer solution, it is possible to increase the bonding strength.

[Third Embodiment] The third embodiment is provided as a joining method for joining a metal base material and a resin base material. The third embodiment of the bonding method includes applying a polymer solution containing a water-soluble polymer having a functional group to the surface of the metal base material, and bonding the water-soluble polymer with the groups present on the surface of the metal base material. The method includes the steps of: forming a chemically bonded layer that is fixed to the surface of the metal base material by bonding; and melting the resin base material and fusing it to the chemically bonded layer that is fixed to the metal base material. .
According to the third embodiment of the bonding method, it is possible to easily form a chemical bonding layer that adheres to the metal base material by chemical bonding by applying a polymer solution. In addition, high bonding strength between the resin base material and the metal base material can be obtained by the molten resin base material entering and being mixed with the chemical bonding layer fixed to the metal base material. Therefore, joining the metal base material and the resin base material can be facilitated.

[Fourth Embodiment] The bonding method of the fourth embodiment further includes a step of degreasing and cleaning an area to which the polymer solution is applied on the surface of the metal base material, before applying the polymer solution to the metal base material. It's fine.
According to the joining method of the fourth embodiment, the joining strength between the metal base material and the resin base material can be further increased.

[Fifth Embodiment] The bonding method of the third or fourth embodiment may include a step of performing plasma treatment on the application area before applying the polymer solution to the metal base material. .
According to the joining method of the fifth embodiment, the joining strength between the metal base material and the resin base material can be further increased.

[Sixth Embodiment] The bonding method according to any one of the third, fourth, and fifth embodiments further includes the step of applying the polymer solution to the metal base material. The method may include a step of removing an oxide film on the surface where the polymer solution is applied.
According to the joining method of the sixth embodiment, the joining strength between the metal base material and the resin base material can be further increased.

[Seventh Embodiment] In the bonding method according to any one of the third, fourth, fifth, and sixth embodiments, the polymer solution fuses the chemically bonded layer to the resin base material. may include inorganic powders that melt at ambient temperatures.
According to the bonding method of the seventh embodiment, the bonding strength between the metal base material and the resin base material can be further increased by fusion of the inorganic powder.

[Eighth Embodiment] In the joining method of any one of the third, fourth, fifth, sixth, and seventh embodiments, the resin base material is joined via the joining layer. preparing the metal base material as a first metal base material; and melting the resin base material onto the chemical bonding layer of the second metal base material formed by applying the polymer solution to a second metal base material. and fusion bonding.
According to the bonding method of the eighth embodiment, two metal base materials can be easily bonded via a resin base material.

The present invention can also be realized in various forms other than the bonding method. For example, the polymer solution used in the bonding method, a metal base material having a chemically bonded layer formed by the polymer solution, a bonded body of the metal base material and a resin base material, various products using the bonded body, It can be realized in the form of a method for manufacturing these joined bodies or products, an apparatus for implementing the above-mentioned joining method or manufacturing method, a control unit or a control program for the apparatus, and the like.

FIG. 3 is an explanatory diagram showing steps of a joining method. FIG. 3 is a schematic diagram showing the contents of each step of the joining method. An explanatory diagram summarizing production examples of polymer solutions. An explanatory diagram for explaining a tensile test for measuring bonding strength. Reference diagram of the first experimental example. The first reference diagram of the second experimental example. The second reference diagram of the second experimental example. The third reference diagram of the second experimental example. The fourth reference diagram of the second experimental example. The first explanatory diagram summarizing the results of the third experimental example. A second explanatory diagram summarizing the results of the third experimental example. FIG. 7 is a schematic diagram showing the contents of each step of the joining method of the second embodiment.

Hereinafter, preferred embodiments and examples of the present invention will be described with reference to the drawings.

1. First embodiment:
FIG. 1 shows a flowchart showing the steps of the joining method of the first embodiment. FIGS. 2A to 2E are schematic diagrams showing the contents of each step S10 to S40 in the joining method of the first embodiment in the order of the steps. 2(a) is a reference diagram of step S10, FIG. 2(b) is a reference diagram of step S20, FIG. 2(c) is a reference diagram of step S30, and FIG. 2(d) is a reference diagram of step S30. , (e) are reference diagrams of step S40.

In the joining method of the first embodiment, the metal base material 10 and the resin base material 20 are joined. In this specification, the term "base material" is used to broadly mean members to be processed, members constituting products, etc., and can also be referred to as "raw material." The types of metal base material 10 and resin base material 20 are not particularly limited, but suitable examples include the following.

<Suitable example of metal base material>
Aluminum (Al), Al alloy, copper (Cu), Cu alloy, nickel (Ni), Ni alloy, iron (Fe), cold rolled steel sheet (SPCC), galvanized steel sheet (SECC, SGCC, SEHC, etc.), carbon Tool steel (SK material), carbon steel for machine structures (SC material), stainless steel, general mild steel material, ultra-high tensile strength steel, and various other metals, alloys, steel materials, etc.

<Suitable example of resin base material>
Polyamide (PA) resins such as PA6 and PA66, polybutylene tephthalate (PBT), polyphenylene sulfide (PPS), polyethylene terephthalate (PET), carbon fiber reinforced thermoplastic resin (CFRTP), ABS resin, polyethylene (PE) , polypropylene (PP), polyacetal (POM), vinyl chloride (PVC), other plastics, rubber, thermoplastic resins, and other synthetic resins that soften when heated.

In step S10, the joining surface of the metal base material 10 is surface-treated as a preparation for joining. This surface treatment is performed at least on a coating area CA of the joint surface to which a polymer solution to be described later is applied. In FIG. 2(a), the application area CA is shown by a broken line for convenience.

As the surface treatment, for example, degreasing and cleaning, surface modification by plasma treatment, etc. can be adopted. This surface treatment can improve the adhesion of the chemical bonding layer 32 shown in FIG. 2(d), which will be described later, to the metal base material 10, and can increase the bonding strength between the metal base material 10 and the resin base material 20. .

From the viewpoint of increasing the bonding strength between the metal base material 10 and the resin base material 20, it is preferable that at least one of degreasing cleaning and plasma treatment is performed as the surface treatment in step S10. Moreover, in step S10, it is more preferable to perform plasma treatment after degreasing and cleaning. The reason why plasma treatment is suitable will be described later.

In step S10, as the surface treatment, in addition to or instead of degreasing and plasma treatment, an oxide film removal process for removing an oxide film in the coating area may be performed. The oxide film removal treatment as surface treatment is preferably combined with degreasing cleaning and plasma treatment. The oxide film removal process is performed, for example, by applying an oxide film removing agent such as sulfuric acid or hydrochloric acid to the application area CA of the metal base material 10. By performing the oxide film removal treatment, the adhesion of the chemical bonding layer 32 to the metal base material 10 can be further improved.

In addition to the above-mentioned surface treatment in step S10, for example, a process of removing foreign matter from the joint surface of the metal base material 10 using a brush or the like may be performed. Note that the surface treatment in step S10 may be omitted depending on the type of metal base material 10, the surface quality and condition of the bonding surface, etc.

In step S20, the polymer solution 30 is applied to the application area CA of the joint surface of the metal base material 10. The polymer solution 30 is composed of a liquid containing a resin component that forms a chemical bond with the bonding surface of the metal base material 10 . The polymer solution 30 contains a water-soluble polymer having a functional group, which corresponds to the resin component described above. In this specification, "liquid" also includes a paste-like liquid with high viscosity.

As the water-soluble polymer, for example, polyacrylic acid amide, sodium polyacrylate, sodium carboxymethylcellulose, etc. can be used. The water-soluble polymer is not limited to the above-mentioned polymers, and any polymer that can form the chemically bonded layer 32 in step S30 may be used.

Preferably, the polymer solution 30 contains an inorganic solvent. The inorganic solvent may be, for example, water such as purified water. Although it is possible not to use an inorganic solvent in the polymer solution 30, in this case, the applicability of the polymer solution 30 may deteriorate. The ratio of the mass percent concentration of the water-soluble polymer and the inorganic solvent can be set as appropriate, for example, within the range of 1:0.01 to 99. The ratio of the mass percent concentrations of the water-soluble polymer and the inorganic solvent may be, for example, 1:0.02, 1:0.5, or 1:1. The ratio of the mass percent concentration of the water-soluble polymer and the inorganic solvent may be, for example, 1:10, 1:20, 1:50, 1:70, or 1: It may be set to 90. Note that the above ratio values allow an error within a range of ±20%.

In addition to the water-soluble polymer, liquid paraffin, surfactant, alcohol, etc. may be added to the polymer solution 30 as appropriate additives. If liquid paraffin is added, the polymer solution 30 can be made cloudy and its visibility can be improved, and the coatability of the polymer solution 30 can be improved. The viscosity of the polymer solution 30 can be adjusted by adjusting the amount of the surfactant added. By adding alcohol, oxidation of the polymer solution 30 can be prevented. As the alcohol, for example, ethanol, polyvinyl alcohol (PVA), etc. can be used. Note that it is preferable that no organic solvent be used in the polymer solution 30.

The polymer solution 30 may contain an inorganic powder that will be melted together with the resin component in the step of fusing the resin base material 20 in step S40, which will be described later. For example, an inorganic powder that melts at the heating temperature of the resin base material 20 in step S40 may be added. In this case, the inorganic powder preferably has a melting point lower than the melting point of the resin base material 20. If such an inorganic powder is added to the polymer solution 30, the effect of fusion of the inorganic powder is added, and the bonding strength between the metal base material 10 and the resin base material 20 can be improved. As the inorganic powder, for example, tin (Sn) powder can be used.

In step S20 of this embodiment, as shown in FIG. 2(b), a paste-like polymer solution 30 is applied to the bonding surface of the metal base material 10 using a coating device such as a die coater. In other embodiments, the polymer solution 30 may be applied by dropping and spreading onto the bonding surface of the metal substrate 10. The polymer solution 30 may be applied by dipping, in which the joint surface of the metal substrate 10 is immersed in the polymer solution 30. Alternatively, the polymer solution 30 may have a low viscosity and be applied to the joint surface of the metal base material 10 by spraying or the like.

The thickness of the coating layer of the polymer solution 30 is preferably, for example, 10 μm or more and 150 μm or less. The thickness of the coating layer of the polymer solution 30 is more preferably 50 μm or more, and even more preferably 80 μm or more. The thickness of the coating layer of the polymer solution 30 is more preferably 130 μm or less, and even more preferably 110 μm or less.

In step S30, the polymer solution 30 applied to the metal base material 10 is dried. As a result, a chemical bonding layer 32 that is fixed to the surface of the metal base material 10 by chemical bonding is formed. According to the findings of the inventor of the present invention, when the polymer solution 30 is dried, a dehydration condensation reaction occurs, and the functional groups of the water-soluble polymer are shared with the groups present on the entire surface of the metal base material 10. It is presumed that they are combined to form a chemically bonded layer 32 of water-soluble polymer. Further, the functional groups of the water-soluble polymer are considered to be bonded to the hydroxyl groups (OH groups) fixed on the surface of the metal base material 10 through ester bonds.

Note that in the surface treatment in step S10 described above, if plasma treatment is performed, the number of OH groups on the bonding surface of the metal base material 10 can be increased. Therefore, it is possible to effectively improve the adhesion of the chemical bonding layer 32 to the metal base material 10.

In step S40, the resin base material 20 is melted and fused to the chemical bonding layer 32. In step S40 of this embodiment, as shown in FIG. 2D, the resin base material 20 is heated to a temperature equal to or higher than its melting point to melt it, and is pressed onto the chemical bonding layer 32 to fuse it. This step can be performed, for example, by hot pressing. As a result, as shown in FIG. 2(e), the resin component of the resin base material 20 melts and enters the chemical bonding layer 32 and is mixed, forming a bonding layer 35 that constitutes a bonding site, and A joined body of 10 and the resin base material 20 is completed.

The heating temperature in step S40 is preferably, for example, 200°C or more and 350°C or less. If the heating temperature is 200° C. or higher, it is possible to melt various resin materials. In order to more easily melt various types of resin base materials 20, the heating temperature is preferably 250°C or higher, more preferably 280°C or higher. It is more preferable that the heating temperature is 330°C or higher. When the heating temperature is set to 330° C. or lower, the resin base material 20 can be efficiently melted while suppressing an increase in energy consumption for heating.

Note that the above-mentioned step S30 and step S40 may be executed in parallel as described below. After applying the polymer solution 30 to the metal base material 10 in step S20, the resin base material 20 is placed on top of the polymer solution 30 before the polymer solution 30 is completely dried. If the polymer solution 30 and the resin base material 20 are heated together in this state, the polymer solution 30 dries and the chemically bonded layer 32 is formed, and in parallel, the resin base material 20 is melted and the chemically bonded layer 32 is formed. A resin component is mixed into the mixture. With this method, it is possible to shorten the time required for the joining process of joining the metal base material 10 and the resin base material 20.

Moreover, in the above step S40, instead of disposing the resin base material 20 on the chemical bonding layer 32 and then melting it by heating, the resin base material 20 after being melted by heating is disposed on the chemical bonding layer 32. It may also be cured and fused. With this method, it is possible to form a molded article of the resin base material 20 on the chemical bonding layer 32 by injection molding. Therefore, compared to the case where the molded resin base material 20 is joined to the metal base material 10, the need for a design that takes the joining process into consideration is reduced, and the degree of freedom in designing the resin base material 20 can be increased. . Furthermore, deformation of the resin base material 20 during the bonding process can be avoided.

In step S40, the resin base material 20 may be melted by a method other than raising the temperature using a heating means such as a heater. The resin base material 20 may be melted by, for example, laser irradiation, ultrasonic irradiation, friction, or the like.

As described above, according to the joining method of the present embodiment, the metal base material 10 and the resin base material 20 are bonded by applying and drying the polymer solution 30 to the metal base material 10 and melting and curing the resin base material 20. It is possible to join easily. Moreover, high bonding strength between the metal base material 10 and the resin base material 20 is realized by the chemical bonding of the water-soluble polymer to the metal base material 10 and the fusion of the resin base material 20 to the chemical bonding layer 32. Furthermore, according to the bonding method of the present embodiment, the bonding strength between the metal base material 10 and the resin base material 20 can be increased by a simple preparation step of surface treatment of the bonding surface of the metal base material 10 before applying the polymer solution 30. can be effectively increased.

In addition, in the bonded body formed by the bonding method of this embodiment, since the bonding layer 35 exhibits sealing properties, deterioration of the bonded interface due to water intrusion or entry of outside air is suppressed, and aging deterioration of bond strength is suppressed. Is possible. In addition, the polymer solution 30 used in the bonding method of this embodiment can be prepared without using an organic solvent, so it is easy to handle and has a small impact on the global environment even if it is discarded. .

Examples of the joining method of the first embodiment will be described in detail below with reference to FIGS. 3 to 11. In this example, a metal base material and a resin base material were joined by the joining method described in the first embodiment above, and the joint strength between the metal base material and the resin base material was measured by a tensile test described below. .

<Production example of polymer solution>
The table in FIG. 3 summarizes production examples of the four types of polymer solutions used in this example. In the following description and reference figures, the types of polymer solutions are indicated by the symbols PAA, PAAs, PAN, and CMC shown in the table of FIG.

Polymer solution PAA was prepared by mixing polyacrylic acid amide as a water-soluble polymer and purified water as an inorganic solvent. The polymer solution PAAs was prepared by mixing polyacrylic acid amide as a water-soluble polymer and purified water as an inorganic solvent, and further adding Sn powder as an inorganic powder. Polymer solution PAN was prepared by mixing sodium polyacrylate as a water-soluble polymer and purified water as an inorganic solvent. Polymer solution CMC was prepared by mixing sodium carboxymethylcellulose as a water-soluble polymer and purified water as an inorganic solvent.

Additives such as liquid paraffin, surfactant, and alcohol were appropriately added to each of the polymer solutions PAA, PAAs, PAN, and CMC in order to improve their handling properties. However, since the influence of these additives on the bonding strength is small, details such as specific types and amounts added will be omitted.

<Tensile test>
The tensile test conducted in this example will be explained with reference to FIG. 4. In FIG. 4, for convenience, the metal base material MM and the resin base material RM to be tested are shown separated by solid lines and dashed lines, respectively, and the application area CA of the polymer solution on the metal base material MM is hatched. It has been done. Further, in FIG. 4, the horizontal width of the application area CA is indicated by x, and the vertical width is indicated by y. The application area CA corresponds to the bonding area between the metal base material MM and the resin base material RM.

A polymer solution was applied to the coating area CA at one end of the plate-shaped metal base material MM having a rectangular plate surface to form a chemical bonding layer. A plate-shaped resin base material RM having a rectangular plate surface is arranged such that its longitudinal direction coincides with the longitudinal direction of the metal base material MM, one end thereof is placed on the chemical bonding layer, and the other end side is placed on the metal base material MM. They were laminated in such a way that they extended from above, and were fused together by hot pressing. By applying a tensile force in the longitudinal direction to the obtained joined body of the metal base material and the resin base material until the joint layer of the joint portion of the metal base material and the resin base material breaks, the joint strength (MPa), And the bonding force (N) was measured.

<First experimental example>
FIG. 5A shows a table summarizing the configurations of Examples E1 and E2 and Comparative Examples C1 and C2. FIG. 5(b) shows a bar graph showing the measurement results of the bonding strengths of Examples E1 and E2 and Comparative Examples C1 and C2.

As shown in FIG. 5(a), in Examples E1 and E2 and Comparative Examples C1 and C2, A5052, which is an alloy of Al and magnesium (Mg), was used as the metal base material MM, and polyamide was used as the resin base material RM. A PA6 resin was used. Further, in Examples E1 and E2 and Comparative Examples C1 and C2, the horizontal width x of the bonding region was 20 mm, and the vertical width y was 3 mm.

In Example E1, a chemical bonding layer was formed on the metal base material MM using a polymer solution PAAs, and a resin base material RM was fused to the chemical bonding layer by hot pressing. In Example E2, a chemical bonding layer was formed on the metal base material MM using the polymer solution PAA, and the resin base material RM was fused to the chemical bonding layer by hot pressing. In both Examples E1 and E2, the application area CA of the metal base material MM before the polymer solution was applied was subjected to degreasing cleaning and plasma treatment. Further, in both Examples E1 and E2, the polymer solution was applied to a film thickness of approximately 50 μm.

In Comparative Example C1, only plasma treatment was performed on the bonding area of the metal base material MM, and the resin base material RM was fused to the metal base material MM by hot pressing without forming a chemical bonding layer using a polymer solution. . In Comparative Example C2, only the bonding area of the metal base material MM was degreased and cleaned, and the resin base material RM was fused to the metal base material MM by hot pressing without forming a chemical bonding layer using a polymer solution. . Ethanol was used for degreasing and cleaning.

The hot pressing conditions in Examples E1, E2, C1, and C2 are the same. The heating temperature in the hot press was higher than the melting points of PA6 and Sn.

As shown in FIG. 5(b), both Examples E1 and E2 were able to obtain higher bonding strength than the two Comparative Examples C1 and C2. This result shows that the improvement in bonding strength in Examples E1 and E2 was achieved by the chemical bonding layer formed by the polymer solution. Furthermore, considering that the bonding strength with conventional adhesives is about several MPa, the bonding strengths obtained in Examples E1 and E2 exceeded 12.0 MPa, indicating that the bonding performance was significantly improved. I understand.

In particular, Example E1 was able to obtain higher bonding strength than Example E2. The bonding strength of Example E1 was improved because the Sn powder added to the polymer solution was melted by heating during hot pressing and fused to the metal base material MM and the resin base material RM. it is conceivable that.

<Second experimental example>
FIG. 6 shows a table summarizing the measurement results of the bonding strengths of Examples E3, E4, E5, E6, E6a, E7, E7a, E8, and E9. In Examples E3, E4, E5, E6, E6a, E7, E7a, E8, and E9, degreasing cleaning and plasma treatment were performed on the application area CA of the metal base material MM before applying the polymer solution. did. The hot pressing was performed under the same pressure and at a heating temperature higher than the melting point of the resin base material RM.

Examples E3, E4, and E5 were conducted under the same conditions except that polymer solutions PAA, PAN, and CMC were used, respectively. In Examples E3, E4, and E5, A5052 was used for the metal base material MM, and PA6 was used for the resin base material RM. Further, the horizontal width x of the bonding area was 20 mm, and the vertical width y was 5 mm. In Examples E3, E4, and E5, bonding forces exceeding 1000 N were obtained. In particular, in Example E4, a bonding strength exceeding 2000N was obtained.

In Example E6, a polymer solution PAA was used, Cu was used as the metal base material MM, and PA6 was used as the resin base material RM. In Example E7, polymer solution PAN was used, SPCC was used as the metal base material MM, and PA6 was used as the resin base material RM. In Examples E6 and E7, the horizontal width x of the bonding area was 20 mm, and the vertical width y was 10 mm. In both Examples E6 and E7, bonding forces exceeding 1000N were obtained. In particular, in Example E6, a bonding force exceeding 2000N was obtained.

Examples E6a and E7a were conducted under substantially the same conditions as Examples E6 and E7, except that the oxide film in the coating area CA was removed before applying the polymer solution. As a result, in Example E6a, the bonding force was improved by 900 N or more compared to Example E6, and in Example E7a, the bonding force was improved by 1800 N or more compared to Example E7. From this result, according to the bonding method of the present invention, the bonding strength between the metal base material and the resin base material can be easily improved by simply performing the process of removing the oxide film in the application area CA before applying the polymer solution. It turns out that you can do it.

Examples E8 and E9 were conducted under the same conditions except that SUS and SGCC were used as the metal base material MM. In Examples E8 and E9, polymer solution PAN was used and PA6 was used as the resin base material RM. In Examples E6 and E7, the horizontal width x of the bonding area was 20 mm, and the vertical width y was 10 mm. In both Examples E8 and E9, a bonding force of 1000 N or more was obtained. In particular, in Example E8, a bonding force of 1800N or more was obtained.

As described above, according to Examples E3, E4, E5, E6, E6a, E7, E7a, E8, and E9, polyamide resin and metal such as Al alloy, Cu, and steel are bonded with a bonding force exceeding 1000N. I was able to join it with strength. Moreover, high bonding strength could be obtained regardless of whether polymer solution PAA, PAN, or CMC was used.

FIG. 7 shows a table summarizing the types of base materials and polymer solutions used in Example E10 and photographed images showing the states of the metal base material MM and resin base material RM after the tensile test. In Example E10, A5052 was used as the metal base material MM, and PBT was used as the resin base material RM. In Example E10, a chemically bonded layer was formed by applying the polymer solution PAA to the metal substrate MM. The resin base material RM was fused to the chemical bonding layer by hot pressing at a heating temperature higher than the melting point of PBT. In Example E10, the application area CA of the metal base material MM before the polymer solution was applied was subjected to degreasing cleaning and plasma treatment.

As shown in the photographed image of Example E10, a portion of the resin base material RM remained at the fractured joint site of the metal base material MM. From this photographed image, it can be seen that in Example E10, sufficient bonding strength to withstand practical use was obtained.

FIG. 8 shows a table summarizing the types of base materials and polymer solutions used in Example E11 and photographed images showing the states of the metal base material MM and resin base material RM after the tensile test. In Example E11, a 980 MPa class high tensile strength steel plate (high tensile steel plate) was used as the metal base material MM, and PA66 was used as the resin base material RM. In Example E11, the polymer solution PAA was applied to the metal base material MM to form a chemically bonded layer. The resin base material RM was fused to the chemical bonding layer by hot pressing at a heating temperature higher than the melting point of PA66. In Example E11, the application area CA of the metal base material MM before the polymer solution was applied was subjected to degreasing cleaning and plasma treatment.

As shown in the photographed image of Example E11, a portion of the resin base material RM remained at the fractured joint site of the metal base material MM. From this photographed image, it can be seen that sufficient bonding strength for practical use was obtained in Example E11 as well.

FIG. 9 shows a table summarizing the combinations of base materials to be bonded and the bonding results for the above examples. Further, in FIG. 9, a table regarding the joining results of the comparative example is added on the right side. In the comparative example, it was verified whether or not metal substrates could be bonded together using a polymer solution. In the table of FIG. 9, "0" means a good result in which a bonding strength equal to or higher than the reference value was obtained. "x" means an unsatisfactory result in which the bonding strength above the standard value was not obtained. "-" means a combination that has not yet been implemented.

As shown in FIG. 9, according to the joining method of the present invention, it was possible to join metals including various alloys and steels to resin. Further, as shown in the results of the comparative example, it was not possible to obtain bonding strength between metals. This result shows that the polymer solution of the present invention is different from conventional general adhesives, which adhere to objects by drying and curing. The reason why the bonding strength is obtained in the present invention is that the combination of the adhesion of the chemical bonding layer to the metal base material and the fusion of the resin by mixing the resin component in the chemical bonding layer is important.

<Third experimental example>
FIG. 10 shows a bar graph obtained by an experiment that verified the bonding strength at each bonding temperature, which is the heating temperature in step S40.

In this experimental example, A5052 was used as the metal base material MM, and PA6 was used as the resin base material RM. Further, a chemical bonding layer was formed by applying the polymer solution PAA to a coating area CA having a width of 20 mm and a width of 3 mm, and the resin base material RM was fused to the chemical bonding layer by hot pressing. Note that, before applying the polymer solution PAA, the application area CA was subjected to ethanol cleaning and plasma treatment as surface treatment of the bonding surface.

Here, the melting point of PA6, which is the resin base material RM, is 225°C. From the graph of FIG. 10, it can be seen that high bonding strength is obtained by setting the bonding temperature in hot pressing to a temperature higher than the melting point. Furthermore, it can be seen that the bonding strength is significantly improved by increasing the bonding temperature by 50° C. or more above the melting point.

FIG. 11 shows a table summarizing the experimental results of verifying the bonding temperature for each type of resin base material RM. In this experimental example, a polymer solution PAA was applied to a metal base material MM made of A5052 to form a chemical bonding layer, and a resin base material RM shown in the table was fused by hot pressing. In the table of FIG. 11, "0" means a good result in which a bonding strength equal to or higher than the reference value was obtained. "x" means an unsatisfactory result in which the bonding strength above the standard value was not obtained. "-" means a combination that has not yet been implemented.

In this experimental example, PA6, PA66, PBT, and PPS were used as the resin base material RM. As mentioned above, the melting point of PA6 is 225°C, the melting point of PA66 is 265°C, the melting point of PBT is within the range of 232°C to 267°C, and the melting point of PPS is 275°C. From the results shown in the table of FIG. 11, it can be seen that hot pressing is preferably performed at a bonding temperature approximately 20 to 30° C. higher than the melting point of the resin base material RM.

<Summary>
As described above, the above experimental examples show that according to the bonding method of the present invention, a chemical bonding layer is formed on a metal substrate by applying a polyper solution and a resin substrate is fused to the chemical bonding layer. It was shown that the material and the resin base material can be bonded with high bonding strength.

2. Second embodiment:
FIGS. 12(a) to 12(c) are schematic diagrams showing each step of the joining method of the second embodiment in order. In the joining method of the second embodiment, the two metal base materials 10a and 10b are joined using the method of joining metal and resin described in the first embodiment.

Refer to FIG. 12(a). In the joining method of the second embodiment, first, a first metal base material 10a and a second metal base material 10b to be joined are prepared.

A resin base material 20 is bonded to the first metal base material 10a by the bonding method described in the first embodiment. A bonding layer 35 is formed between the first metal base material 10a and the resin base material 20, in which a part of the molten resin base material 20 is mixed with the chemical bonding layer 32. A chemical bonding layer 32 is formed on the second metal base material 10b by applying a polymer solution.

Refer to FIG. 12(b). Next, the chemical bonding layer 32 formed on the second metal base material 10b is brought into contact with the resin base material 20 joined to the first metal base material 10a, and the resin base material 20 is melted to form a second metal base material. The resin base material 20 joined to the first metal base material 10a is fused to the chemical bonding layer 32 of 10b. This fusion step can be performed by hot pressing the chemically bonded layer 32 of the second metal base material 10b laminated on the resin base material 20 of the first metal base material 10a.

Through the above steps, as shown in FIG. 2(c), the first metal base material 10a and the second metal base material 10b are bonded with the layer of the resin base material 20 having the bonding layer 35 formed on both sides sandwiched therebetween. A bonded body is formed.

According to the joining method of the second embodiment, the two metal base materials 10a and 10b can be easily joined. Further, the two metal base materials 10a and 10b can be joined while being electrically insulated by the resin base material 20. In addition, according to the joining method of the second embodiment, various effects described in the first embodiment and its examples can be achieved.

3. Other embodiments:
The present invention is not limited to the configurations described in the above embodiments and examples, and can be modified as appropriate without departing from the spirit of the present invention. The configurations described as other embodiments in each of the above embodiments and the configurations described below are positioned as one form for implementing the present invention, similarly to each of the above embodiments and examples.

The bonding methods described in each of the above embodiments and examples may be combined with other bonding methods. For example, it may be combined with a method in which a fine uneven structure is formed on the surface of the steel material and a softened resin base material is inserted into the uneven structure to bond the steel material. The above-mentioned fine uneven structure of the steel material can be obtained by disposing metal powder containing at least titanium, carbon, nickel, and tin on the surface of the steel material, and melting the metal powder by laser irradiation. It may be formed by The details are disclosed in, for example, Japanese Patent Laid-Open No. 2022-187439.

10, 10a, 10b, MM...metal base material, 20, RM...resin base material, 30...polymer solution, 32...chemical bonding layer, 35...bonding layer, CA...coating area

Claims (8)

a first step of performing at least one of degreasing and cleaning and surface modification by plasma treatment on the joint surface of the metal material;
A second step of preparing a polymer solution containing a resin component that chemically bonds with the bonding surface of the metal material that has undergone the first step by heating, and applying it onto the bonding surface to form a chemical bonding layer. process and
a third step of preparing a resin material containing a resin component that melts and mixes with the chemical bonding layer to bond with the chemical bonding layer by heating;
The resin material prepared in the third step is laminated on the polymer solution applied in the second step and heated and pressed, or the resin material is injection molded to form the metal. A joining method for joining a material and the resin material. The joining method according to claim 1, comprising:
A bonding method characterized in that the polymer solution contains an inorganic powder that melts at a temperature during bonding. A joining method for joining a metal base material and a resin base material, the method comprising:
A polymer solution containing a water-soluble polymer having a functional group is applied to the surface of the metal base material, and the surface of the metal base material is formed by covalent bonding between the water-soluble polymer and the group present on the surface of the metal base material. forming a chemical bonding layer that adheres to the
melting the resin base material and fusing it to the chemical bonding layer fixed to the metal base material;
A joining method comprising: 4. The joining method according to claim 3, further comprising:
A joining method comprising the step of degreasing and cleaning an area to which the polymer solution is applied on the surface of the metal base before applying the polymer solution to the metal base. The joining method according to claim 3,
Before applying the polymer solution to the metal substrate, performing plasma treatment on the application area;
A joining method comprising: 4. The joining method according to claim 3, further comprising:
A joining method comprising, before applying the polymer solution to the metal base material, removing an oxide film in an area where the polymer solution is applied on the surface of the metal base material. The joining method according to claim 3,
The bonding method, wherein the polymer solution includes an inorganic powder that melts at a heating temperature when fusing the resin base material to the chemical bonding layer. The joining method according to any one of claims 3 to 7,
preparing the metal base material to which the resin base material is bonded via the bonding layer as a first metal base material;
Melting and fusing the resin base material to the chemical bonding layer of the second metal base material formed by applying the polymer solution to the second metal base material;
A joining method comprising:

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