Composite material formed by bonding dissimilar metal materials and resin, and method for manufacturing the same.

Abstract

In composite materials combining resin and clad material, the bonding strength between the resin and clad material is improved, and the degree of design freedom is also increased, making them suitable for use in mobile products and components for mobile machinery. [Solution] The surface of the clad material 2 is treated with a chemical conversion treatment to form a surface state with fine irregularities suitable for bonding both metal surfaces with resin. The chemical conversion treatment uses an acidic aqueous solution to treat the metal that has the lowest ionization tendency and is difficult to dissolve among the dissimilar metals, forming irregularities by etching. A resin outer frame 5 is then integrated into the clad material 2 with the formed fine irregularities by injection molding or hot pressing to obtain a composite material 1 of clad material and resin.

Description

Technical Field

[0001] The present invention relates to a joined composite of two or more metals and a resin, that is, a joined composite of a dissimilar metal material and a resin, and a method for producing the same. More specifically, the present invention relates to a clad material obtained by joining dissimilar metals (composite metal materials), or a joined composite of a metal and a resin mechanically fixed and joined, and a method for producing the same.

Background Art

[0002] Technologies for firmly integrating metals and synthetic resins are required in a wide range of industrial fields such as the manufacturing of parts for automobiles, household electrical appliances, and industrial equipment. For this purpose, many adhesives have been developed. Among them, very excellent adhesives are also commercially available. However, more rational joining methods that do not use adhesives have also been studied conventionally and have already been put into practical use and commercialized. That is, for metals and alloys such as magnesium, aluminum, copper, titanium, stainless steel, general steel materials, and further steel materials such as aluminum-plated steel sheets and zinc-plated steel sheets, special steels, etc., a method of integrating them with a high-strength engineering resin without the intervention of an adhesive. These are also technologies proposed by the present inventors. In order to firmly fix the resin, fine irregularities are formed on the surface by chemical conversion treatment. This metal-shaped object is inserted into an injection molding die, and a specific thermoplastic resin composition is injected into it. While the resin part is injection molded, the molded product and the metal-shaped object are fixed at the same time (hereinafter referred to as "injection joining").

[0003] In injection bonding, surface treatment methods for aluminum alloys before injection bonding aluminum alloys or magnesium alloys with resins have been proposed by the applicant and others (for example, Patent Documents 1, 2, 3, etc.). Similarly, the applicant has proposed an optimal chemical treatment for stainless steel before injection bonding with resins such as PPS and aromatic polyamides (for example, Patent Document 4, etc.). Likewise, the applicant has proposed chemical treatments for metals before injection bonding copper or copper alloys with resins such as PBT or PPS (Patent Document 5), metals before injection bonding titanium alloys with resins such as PBT or PPS (Patent Document 6), metals before injection bonding general steel materials with resins such as PBT or PPS (Patent Document 7), metals before injection bonding aluminum-plated steel sheets with resins such as PBT or PPS (Patent Document 8), and metals before injection bonding zinc-plated steel sheets with resins such as PBT or PPS (Patent Document 9).

[0004] To increase bonding strength when joining resin to a metal surface, a method has been proposed in which laser light is scanned vertically and horizontally to create uneven surfaces, instead of the chemical conversion treatment described above (Patent Documents 10 and 11). Furthermore, a metal-resin composite with excellent gas sealing properties, where gas molecules have extremely difficulty passing through the bonding boundary between an aluminum alloy and a molded product of a thermoplastic resin such as PPS, and a method for manufacturing the same have been proposed (Patent Document 9). On the other hand, clad materials, which are made by joining two or more metals, are known to be able to achieve performance that cannot be obtained with a single metal because they combine multiple properties of the constituent metals, and are used in various fields.

[0005] Clad materials, which integrate two or more metals, have long been used in various products and enjoy a certain level of demand. Among these, clad materials combining the weather resistance of stainless steel with the lightness of aluminum are highly valued as materials that can be used outdoors without restrictions. Other clad materials, such as aluminum or aluminum alloys with copper or copper alloys, and stainless steel with copper or copper alloys, are used in battery materials and electrodes. Currently, many injection-bonded products are used in the casings of mobile devices such as smartphones, tablets, and laptops. While many of these use aluminum alloys, there is room for further improvement in terms of appearance, weather resistance, and chemical resistance. However, using stainless steel, which is known for its high strength and weather resistance, would result in excessive weight, making it unsuitable for mobile products like smartphones and tablets.

[0006] To address aesthetic and weight issues, the use of weather-resistant and lightweight metals, such as clad materials, is considered suitable. Furthermore, by bonding clad materials with resin, aesthetic issues and weight reduction can be achieved. Demand for mobile device bodies and components made with this bonded clad material and resin is expected to increase in the future. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2003-200453 [Patent Document 2] Japanese Patent Publication No. 2007-050630 [Patent Document 3] WO2008 / 06952 issue [Patent Document 4] WO2008 / 081933 [Patent Document 5] WO2008 / 047811 [Patent Document 6] WO2008 / 078714 [Patent Document 7] WO2009 / 011398 issue [Patent Document 8] WO2009 / 084648 issue [Patent Document 9] WO2009 / 116484 [Patent Document 10] WO2007 / 072603 [Patent Document 11] Japanese Patent Publication No. 2015-142960 [Patent Document 12] WO2012 / 070654 issue [Overview of the project] [Problems that the invention aims to solve]

[0008] The injection molding method proposed by the applicants to integrate metal and resin using insert molding requires different surface treatment methods for each type of metal. Therefore, it cannot be applied to composites of dissimilar metals and resins integrated using cladding materials, riveting, etc. This is because metals form fine irregularities through immersion treatment, and cladding materials composed of dissimilar metals are unsuitable for immersion treatment due to the different surface chemical treatment methods required for each metal type. If it were possible to chemically treat multiple dissimilar metals in cladding materials simultaneously, it would be possible to efficiently create weather-resistant, high-strength, and lightweight parts, and would also increase the freedom of decoration for mobile device components. As a solution, it is crucial to develop surface treatments suitable for joining dissimilar metals integrated using cladding materials, riveting, etc. However, integrated dissimilar metals exhibit different reactions from individual chemical treatments due to differences in ionization tendencies. This reaction is based on the same principle as what is commonly known as galvanic corrosion. In other words, metals with a high ionization tendency dissolve more easily, while metals with a low ionization tendency dissolve less easily, so it is clear that the process is different when treating a single metal. Furthermore, the chemicals used for surface treatment differ depending on the metal, and there is a possibility of affecting metals other than the intended target.

[0009] The object of the present invention is to provide a composite material for bonding dissimilar metal materials and resins, comprising a composite metal material and a resin with different surface treatment conditions for chemical conversion, and a method for manufacturing the same. Another object of the present invention is to provide a method for manufacturing a composite material of dissimilar metals and resin, which can efficiently and simultaneously form fine irregularities in the composite metal material by immersion treatment. [Means for solving the problem]

[0010] The composite material of dissimilar metal materials and resin according to the present invention 1 is A composite metal material formed by joining two or more types of metals together, A synthetic resin integrally bonded with the aforementioned composite metal material A composite material consisting of dissimilar metals and resin, The composite metal material is characterized in that fine irregularities of 10 nm to 100 nm are formed on its surface, and the synthetic resin penetrates into these fine irregularities and is bonded to them.

[0011] The composite of dissimilar metal materials and resin according to the second invention is characterized in that, in the first invention, the composite metal material consists of pure aluminum or an aluminum alloy and stainless steel. The composite of dissimilar metal materials and resin according to Invention 3 is characterized in that, in Invention 1 or 2, the synthetic resin is one or more resins selected from polyphenylene terephthalate, polybutylene terephthalate, polyamide, and polyetheretherketone, or a polymer alloy mainly composed of the said resin.

[0012] The composite of dissimilar metals and resin according to the present invention 4 is characterized in that, in the present invention 1 or 2, the composite metal material is joined by one or more bonding methods selected from pressure welding, riveting, welding, forge welding, and casting.

[0013] The composite of dissimilar metals and resins according to the present invention 5 is characterized in that, in the present invention 1 or 2, the fine irregularities are formed by chemical conversion treatment by etching or surface treatment by anodizing. The joined composite body of dissimilar metals and resin of the present invention 6, in the manufacturing method of the joined composite body of dissimilar metals and resin of the present invention 5, is characterized in that the chemical conversion treatment is performed by forming irregularities by etching with an acidic aqueous solution that treats the metal with the lowest ionization tendency and the lowest solubility in the dissimilar metals, followed by a fine etching treatment with an amine compound.

Effect of the Invention

[0014] The joined composite body of dissimilar metal materials and resin of the present invention and its manufacturing method can firmly integrate dissimilar metal materials (composite metal materials) with different characteristics and resin, so the applications to various devices are broadened and the designability can be enhanced. The chemical conversion treatment of the dissimilar metal materials forms irregularities by etching with an acidic aqueous solution that treats the metal with the lowest ionization tendency and the lowest solubility in the dissimilar metals, so that the immersion treatment can be performed simultaneously and the productivity is good.

Brief Description of the Drawings

[0015] [Figure 1] FIG. 1 shows Embodiment 1 of the joined composite body of dissimilar metal materials and resin of the present invention, and is a structural example of the joined body 1 formed by injecting resin into a plate-shaped clad material. FIG. 1(a) is a cross-sectional view taken at the position of a-a in FIG. 1(b), and FIG. 1(b) is an external view. [Figure 2] FIG. 2 shows Embodiment 2 of the joined composite body of dissimilar metal materials and resin of the present invention, and is a structural example of the joined body 10 formed by injecting resin into a through-hole 11 penetrating a plate-shaped clad material. FIG. 2(a) is a cross-sectional view taken at the position of a-a in FIG. 2(b), and FIG. 2(b) is an external view. [Figure 3] FIG. 3 shows Embodiment 3 of the joined composite body of dissimilar metal materials and resin of the present invention, and is a structural example of the joined body 15 formed by injecting resin into a through-hole penetrating a plate-shaped clad material to form an insulating hole. FIG. 3(a) is a cross-sectional view taken at the position of a-a in FIG. 3(b), and FIG. 3(b) is an external view. [Figure 4] FIG. 4 is a microscopic photograph of the surface of the aluminum material at 100,000 times when subjected to chemical conversion treatment by the method of Experimental Example 1. [Figure 5]Figure 5 is a 100,000x magnification micrograph of the surface of a stainless steel material treated with the chemical conversion method described in Experimental Example 1. [Modes for carrying out the invention]

[0016] Hereinafter, embodiments of the composite material of dissimilar metals and resins of the present invention will be specifically described with reference to the drawings. Figure 1 shows Embodiment 1 of the composite material of dissimilar metals and resins of the present invention, and is an example of the structure of a jointed body 1 constructed by injecting resin into a plate-shaped clad material 2. Figure 1(a) is a cross-sectional view cut at the position aa in Figure 1(b), and Figure 1(b) is an external view. The clad material 2 of this jointed body 1 is made by laminating and joining an aluminum alloy plate 3 and a stainless steel plate 4, and is used, for example, in cooking pots, etc., and consists of an outer frame 5 made of thermoplastic synthetic resin having a packing groove 6 that is injection-bonded to it. Before injection bonding, the surface of the clad material 2 is pre-treated with chemical conversion treatment as in the embodiment described later. The chemically treated clad material 2 is inserted into an injection molding die to form the outer frame 5. A packing 7 made of synthetic resin elastomer may be formed in the packing groove 6 by injection molding. This clad material 2 is lighter than stainless steel alone, and the aluminum alloy plate 3 has superior thermal conductivity and heat dissipation compared to stainless steel alone. The joined body 1 is ideal for electrical equipment housings, mechanical parts, etc., where these properties are required.

[0017] Figure 2 shows Embodiment 2 of the bonding composite of dissimilar metal materials and resin according to the present invention, and is an example of the structure of a bonding composite 10 constructed by injecting resin into through holes 11 that penetrate a plate-shaped clad material. Figure 2(a) is a cross-sectional view taken at position aa in Figure 2(b), and Figure 2(b) is an external view. The bonding composite 10 shown in Figure 2 is an example constructed by injecting resin into through holes 11 that penetrate a plate-shaped clad material. Through holes 11 are made in this clad material 2 by press working, drilling or other machining. The surface of the clad material 2 is chemically treated, similar to bonding composite 1. The chemically treated clad material 2 is inserted into an injection molding die to form protrusions 12 that protrude from the front and back of the clad material 2. These protrusions 12 connect the front and back of the through holes 11 made in the clad material 2 and are firmly fixed to the clad material 2.

[0018] Figure 3 shows a third embodiment of the composite material of dissimilar metals and resin according to the present invention. It is an example of the structure of a composite material 15 formed by injecting resin into through-holes that penetrate a plate-shaped cladding material to form insulating holes. Figure 3(a) is a cross-sectional view taken at position aa in Figure 3(b), and Figure 3(b) is an external view. The composite material 15 shown in Figure 3 has insulating holes 16 that penetrate through-holes 11, and is an insulator 17 made of a resin with high electrical insulation properties. The insulating holes 16 are through-holes for passing wires, etc. [Examples]

[0019] The following examples specifically illustrate a method for chemical treatment of clad materials. Note that "aluminum material" refers to materials containing aluminum and aluminum alloys. In clad materials where stainless steel and aluminum are integrated, it is necessary to form fine irregularities suitable for bonding on both metals by immersion treatments suitable for each metal. Formation of surface irregularities in aluminum material First, the cladding material, consisting of stainless steel and aluminum, is degreased. This degreasing process is not special; it involves removing oil from the surface using solvent degreasing, alkaline surfactants, or neutral detergents. Next, it is washed with a dilute acidic aqueous solution for neutralization. Hydrochloric acid, nitric acid, etc., can be used as acids. The acidic aqueous solution should be concentrated at 0.5-5.0 wt% and at a temperature of 30-60°C. After immersion for several minutes, it is rinsed with pure water. Next, the aluminum material is etched with an alkaline aqueous solution. If sodium hydroxide is used for etching, the concentration should be 0.5-10.0 wt% and the temperature at 30°C-65°C. After immersion for several minutes to several tens of minutes, it is rinsed with pure water.

[0020] Formation of surface irregularities in stainless steel materials Once the etching of the aluminum material described above is complete, the etching of the stainless steel material will be performed. For etching the stainless steel material, the stainless steel is first etched with an acidic aqueous solution. Sulfuric acid is used, with a concentration of 0.5-30.0 w% and a temperature of 40-70°C, after which the material is immersed for several minutes to several tens of minutes and then rinsed with pure water. Alternatively, a few w% of fluoride, such as acidic ammonium fluoride, may be added to the sulfuric acid as a trace component. If nitric acid is used in this acidic aqueous solution treatment, the material is immersed for several minutes with a concentration of 0.5-20.0 w% and a temperature of 30-60°C, and then rinsed with pure water. In addition, these etching processes for stainless steel materials will affect the surface of the aluminum material, but if necessary, it is possible to correct the surface to one suitable for bonding in a later process.

[0021] Micro-etching formation of aluminum material Aluminum materials with a textured surface undergo micro-etching to further create finer irregularities. Micro-etching is performed on the textured surface of the aluminum material by immersion in an aqueous solution of amines. Specifically, the micro-etching treatment uses hydrated hydrazine, immersing it at a concentration of 1.0-20.0 w% and a temperature of 40-70°C for several minutes, followed by rinsing with water. This immersion process does not affect the surface irregularities of the chemically treated stainless steel material. Finally, it is immersed in a dilute aqueous solution of amine. It is presumed that immersion in an aqueous solution of amine with a different concentration than the above immersion treatment promotes the formation of fine irregularities and causes chemical adsorption of amines. In the case of hydrated hydrazine, the concentration is 0.2-5.0 w% and the temperature is 40-70°C, and it is immersed for several minutes. After that, it is thoroughly washed with pure water and dried in a dryer set to 60-70°C for about 10-30 minutes.

[0022] Micro-etching formation of other aluminum materials Another surface treatment method for aluminum materials involves immersing them in acidic potassium permanganate after performing the fine etching process described above. The concentration is 0.5-20.0 w% and the immersion is performed at a temperature of 40°C-65°C for several minutes. After thoroughly washing with pure water, the material is dried in a dryer set to 60°C-70°C for about 10-30 minutes. [Example of experiment]

[0023] The following describes embodiments of the present invention as experimental examples. The equipment used to obtain the data for these experimental examples is as follows: Measurement of the bonding strength of the composite: A tensile testing machine "AG-500N / 1kN (Shimadzu Corporation (Headquarters: Kyoto Prefecture, Japan))" was used to measure the shear fracture force at a tensile speed of 10.0 mm / min.

[0024] [Experimental Example 1] Commercially available overlay crust material with a wall thickness of 1.1 mm (stainless steel material with a wall thickness of 0.2 mm, aluminum material with a wall thickness of 0.9 mm) was cut into rectangular pieces measuring 18 mm x 45 mm to prepare test specimens. An aqueous solution containing 7.5% of the aluminum degreasing agent "NE-6" (manufactured by Meltex Co., Ltd. (headquarters: Tokyo)) was heated to 60°C and the alloy pieces were immersed in it for 5 minutes, then rinsed with tap water. Next, a 1.0% hydrochloric acid aqueous solution was prepared at 40°C in another immersion tank, and the test specimens were immersed in it for 1 minute, after which they were rinsed with water. Next, a 1.5% caustic soda aqueous solution was prepared at 40°C in another immersion tank, and the test specimens were immersed in it for 8 minutes, after which they were rinsed with water. Next, an aqueous solution of 5.0% sulfuric acid aqueous solution with 1.0% acidic ammonium fluoride was prepared at 65°C and the test specimens were immersed in it for 4 minutes, after which they were rinsed with water. Next, the object was immersed in a 3.0% nitric acid solution at 40°C in a separate immersion tank for 3 minutes, and then rinsed with water.

[0025] Next, a 3.5% aqueous solution of hydrated hydrazine, heated to 60°C, was prepared in a separate immersion tank and the specimens were immersed in it for 1 minute. Then, a 0.5% aqueous solution of hydrated hydrazine, heated to 40°C, was prepared in another immersion tank and the specimens were immersed in it for 0.5 minutes, after which they were rinsed with water. The treated specimens were dried in a dryer set to 65°C for approximately 15 minutes to prepare specimens for bonding. Using these specimens and resins, test specimens were prepared using PPS (Sustain "SGX120" manufactured by Toso Corporation (headquartered in Tokyo, Japan)) and PBT (Toray Industries, Inc. (headquartered in Tokyo, Japan)) and Toraycon "1101GX54" manufactured by Toray Industries, Inc. (headquartered in Tokyo, Japan), and injection bonding tests were performed. For injection bonding of PPS resin, the mold temperature was set to 140°C and the resin temperature to 310°C. For injection bonding of PBT resin, the mold temperature was set to 140°C and the resin temperature to 280°C. This data is shown in Table 1. [Table 1] Figure 4 shows a representative example of the surface condition of a test specimen treated with the above chemical conversion treatment, specifically the surface of an aluminum material, and Figure 5 shows a representative example of a stainless steel material surface.

[0026] [Experimental Example 2] Commercially available overlay crust material with a wall thickness of 1.1 mm (stainless steel material with a wall thickness of 0.2 mm, aluminum material with a wall thickness of 0.9 mm) was cut into rectangular pieces measuring 18 mm x 45 mm to be used as test specimens. An aqueous solution containing 7.5% of the above-mentioned aluminum degreasing agent "NE-6" was prepared in a tank at 60°C, and the alloy pieces were immersed in it for 5 minutes, after which they were rinsed with tap water. Next, a 1.0% hydrochloric acid aqueous solution was prepared in a separate immersion tank at 40°C, and the test specimens were immersed in it for 1 minute, after which they were rinsed with water. Next, a 1.5% caustic soda aqueous solution was prepared in a separate immersion tank at 40°C, and the test specimens were immersed in it for 8 minutes, after which they were rinsed with water. Next, an aqueous solution of 5.0% sulfuric acid with 1.0% acidic ammonium fluoride was prepared in a separate immersion tank at 65°C, and the test specimens were immersed for 4 minutes, after which they were rinsed with water. Next, the items were immersed in a 3.0% nitric acid solution at 40°C in a separate immersion tank for 3 minutes, followed by rinsing with water.

[0027] The chemical treatment in Example 2 described above is almost identical to that in Example 1, but the following treatment methods differ. Next, a 3.5% aqueous solution of hydrated hydrazine at 60°C was prepared in a separate immersion tank and the specimens were immersed in it for 2 minutes (1 minute in Example 1). Next, an aqueous solution containing 2.0% potassium permanganate, 1.0% acetic acid, and 0.5% sodium hydrated acetate was prepared at 45°C and the specimens were immersed in it for 5 minutes (this treatment was omitted in Example 1). After that, the specimens were thoroughly washed with pure water. The treated specimens were dried in a dryer set to 65°C for about 15 minutes to prepare specimens for bonding. The injection bonding test data for these specimens and PBT is shown in Table 2. For injection bonding of PPS resin, the mold temperature was set to 140°C and the resin temperature to 310°C. For injection bonding of PBT resin, the mold temperature was set to 140°C and the resin temperature to 280°C. [Table 2] [Explanation of Symbols]

[0028] 1, 10, 15…junction complex 2…Clad material 3…Aluminum alloy plate 4…Stainless steel plate 5…Outer frame 6… Packing groove 7... Gasket 11…Through hole 12...Protrusion 16…Insulation holes 17…Insulator

Claims

1. A composite metal material formed by joining two or more types of metals together, A synthetic resin integrally bonded with the aforementioned composite metal material A composite material consisting of dissimilar metals and resin, The surface of the composite metal material has fine irregularities ranging from 10 nm to 100 nm in size, and the synthetic resin penetrates into these fine irregularities and is bonded to them. A composite material characterized by the bonding of dissimilar metal materials and resin.

2. In the composite of dissimilar metals and resin according to claim 1, The composite metal material is characterized by being composed of pure aluminum or aluminum alloy and stainless steel, and is a composite of dissimilar metals and resin.

3. In the composite of dissimilar metals and resin according to claim 1 or 2, The synthetic resin is one or more resins selected from polyphenylene terephthalate, polybutylene terephthalate, polyamide, and polyether ether ketone, or a polymer alloy mainly composed of the said resin. A composite material characterized by the bonding of dissimilar metals and resins.

4. In the composite of dissimilar metals and resin according to claim 1 or 2, The composite metal materials are joined by one or more bonding methods selected from pressure welding, riveting, welding, forge welding, and casting. A composite material characterized by the bonding of dissimilar metals and resins.

5. In the method for producing a composite of dissimilar metals and resin according to claim 1 or 2, The aforementioned fine irregularities are formed by chemical conversion treatment by etching or surface treatment by anodizing. A method for producing a composite material by joining dissimilar metals and resins, characterized by the above.

6. In the method for producing a composite of dissimilar metals and resin according to claim 5, The aforementioned chemical conversion treatment involves first creating irregularities by etching with an acidic aqueous solution that treats the metal with the lowest ionization tendency and least soluble among the dissimilar metals, and then performing a fine etching treatment with an amine compound. A method for producing a composite material by joining dissimilar metals and resins, characterized by the above.

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