Manufacturing method of composite of CFRP and metal material and the composite

Abstract

To provide composite materials integrating CFRP or CFRTP and high-strength metal materials that can withstand severe temperature impact tests.SOLUTION: A CFRP or CFRTP material with an Al alloy sheet is made by bonding or injection bonding the Al alloy sheet to the CFRP or CFRTP material. The surfaces of the Al alloy sheet and Ti and other metal materials are subjected to conversion treatment. After the conversion treatment, the CFRP or CFRTP material with Al alloy sheet and the metal material are inserted into an injection mold with a gap between them. Highly crystalline thermoplastic resin is injected into this gap, and the metal material and Al alloy sheet are bonded to form a laminated composite, with the difference in linear expansion coefficient between the CFRP or CFRTP material and the metal material being absorbed by the thick layer of highly crystalline thermoplastic resin. Such a laminated composite can withstand severe thermal shock tests, and any common high-strength metal such as duralumin, Ti alloy, etc. can be used as the metal material to be bonded.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a composite of CFRP and a metal material, and the composite. More specifically, the present invention relates to a method for manufacturing a composite of CFRP and a metal material, which is a composite formed by laminating and integrating CFRP, including lightweight, high-strength CFRTP that can be used as a structural material for automobiles, aircraft, etc., with a thick plate-shaped high-strength metal material, and the composite. [Background technology]

[0002] More than 10 years have passed since CFRP (carbon fiber reinforced plastic) began to be used as an ultra-lightweight, high-strength material for the main structural components of large passenger aircraft, such as wings. The wing tips, made of CFRP, need to be fastened to the fuselage, which is made of extra-super duralumin (A7075Al alloy). When fastening CFRP to the metal fuselage, aircraft manufacturers reportedly struggled to design the fastening structure and method. While CFRP possesses mechanical strength comparable to that of high-strength metals, it is essentially a plastic supported by carbon fiber (hereinafter referred to as "CF"). To construct an aircraft structure, it must be firmly fastened (fastened) to the metal. For example, when a fastening structure is used in which holes are drilled in the CFRP material and bolts and nuts are fastened together, overtightening the nuts can destroy the CFRP. One aircraft manufacturer attempted to overcome this fastening structure by developing a nut to prevent overtightening and adopting it in their aircraft. However, this fastening technology has not yet been perfected. It is said that it will be difficult to know how reliable the fastening structure is against long-term fatigue and other issues until more experience is gained.

[0003] CFRP is a fiber-reinforced resin material typically made with CFRP in a thermosetting epoxy resin matrix, and can be bonded to metal components using epoxy adhesives. Therefore, when it is necessary to fasten CFRP to metal components, as mentioned above, adhesives are ideal for achieving weight reduction, rather than mechanical fastening methods such as bolts and nuts. Because adhesive methods have considerable technical potential, aircraft manufacturers and others have conducted research and development into these methods. In the final stage of this research, a riveting method using titanium alloy rivets was adopted in the manufacture of a large passenger aircraft. This suggests that the decision to adopt the bolt and nut fastening method over adhesive bonding was due to the perceived lack of technical challenges. Historically, riveting has been a well-established method for assembling high-strength metal materials. Although riveting, a technology that has been around for over half a century in aircraft applications, is known for its reliability. However, if adhesive-based assembly methods could be put to practical use, they would enable the easier construction of lightweight structures compared to riveting or bolt and nut fastening. In particular, if adhesive fastening of CFRP wings to the metal main structure in the center of the fuselage could be demonstrated to be practical, the technology could be applied not only to large passenger aircraft, but also to small aircraft, military aircraft, high-speed drones, and other aircraft, and performance improvements could be expected through ultra-lightweight designs. Furthermore, it is expected that the technology could be expanded to include mobile machinery other than aircraft, such as automobiles.

[0004] (Problems and issues with adhesive methods) Today, screw fastening structures are widely used in the assembly of various machinery, buildings, and other structures. Adhesive assembly of mechanical structures is a rare fastening method in the machinery manufacturing industry as a whole. A rare example is the use of adhesive structures in the assembly of passenger aircraft fuselages. Adhesive fastening is now used to fasten the rib structure made of A7075 aluminum alloy (extra super duralumin) to the skin plate material made of A2024 aluminum alloy (super duralumin). While rivets were previously used for this fastening, followed by screws or resistance welding, adhesive fastening has become the established method today due to its lightest weight and high reliability. Conversely, adhesive structures are rarely used for the assembly of important structural components outside of aircraft. From another perspective, adhesive fastening methods are only used to join similar metal materials. In other words, the above example is also a bond between extra super duralumin (A7075Al alloy) and super duralumin (A2024Al alloy), or simply put, a bond between aluminum alloys. Why is bonding between CFRP material and A7075Al alloy material, etc. not used in the basic structure of aircraft?

[0005] The inventors of the present invention have developed and proposed a basic technique for strengthening the adhesive strength between various metals and between various metals and CFRP materials, and have named this adhesive method. This adhesive method is called "NAT (short for Nano Adhesion Technology)" (see, for example, Patent Documents 1 to 6). The effect of this adhesive method is, in short, that it can double the adhesive strength using an epoxy adhesive. However, even if the adhesive strength between CFRP and A7075Al alloy is maximized using this NAT, unfortunately, it cannot be used for basic structural components such as aircraft. The reason for this is that the linear expansion coefficients of CFRP and A7075Al alloy are significantly different. Therefore, even if a one-component epoxy adhesive, which is considered to have the highest adhesive strength, is used, or a two-component epoxy adhesive, which can be cured at room temperature, is used, the adhesive layer of the bonded structure obtained using these adhesives is easily destroyed when used over a wide temperature range, for example, from -50°C to +150°C. The reason for setting such temperature range conditions (experimental conditions) is that in the case of aircraft, the environments in which they operate range from the stratosphere to airports in tropical regions, and most of the aircraft exposed to this environment is in the temperature range of -50°C to +80°C, but the areas near the engines and heat-generating equipment such as light emitters are exposed to temperatures in the range of -50°C to +150°C. For this reason, adhesive structures cannot be used in this environmental temperature range, as this would cause abnormalities in the bonding state.

[0006] [Adhesion between CFRP materials] Therefore, as a preliminary test of the present invention, the inventors bonded identical CFRP pieces together with an epoxy adhesive to create bonded pairs (test pieces) with the shape shown in Figure 4(b). These were then placed in a jig (see Figure 3) and their shear bond strengths were measured. The bonding method used here was to roughen the edges of the CFRP pieces with sandpaper, and then bond and cure them with a one-component epoxy adhesive with high adhesive strength. The shear bond strength of these bonded pairs averaged approximately 40 MPa, with a maximum of 55-60 MPa. In all cases, in these tests, the bonded pairs that exhibited the highest shear bond strength, as described above, had traces of CF (carbon fiber) whiskers remaining at the bonded surface after fracture. This evidence clearly indicated that the fracture did not occur between the surface of the CFRP piece and the surface of the cured adhesive, but rather between the CF surface and the matrix resin of the CFRP. In other words, in the latest carbon fiber CF (tensile strength approximately 6 GPa), where the cross section of the carbon fiber is perfectly circular and the sides of the carbon fiber are smooth, the adhesive strength between the CF surface and the thermosetting epoxy resin matrix resin is approximately 40 MPa. On the other hand, in older-type carbon fiber CF (tensile strength approximately 3 GPa), the cross section shape is not perfectly circular, but rather elliptical, diamond-shaped, gourd-shaped, etc., and the fiber sides have vertical stripes and occasional convex and concave portions. Even with this older-type CF, the true adhesive strength between the CF surface and the thermosetting epoxy resin matrix resin is approximately 40 MPa. However, if this is calculated assuming the cross section of the CF is perfectly circular, the apparent adhesive strength is 55 to 60 MPa. In other words, even if a tensile fracture test is performed on a test piece (CFRP on the resin side) such as that shown in Figure 1 in which the above-mentioned NAT-treated metal material and CFRP material are directly bonded together and there is no difference in the linear expansion coefficients, the fracture surface will never be near the surface of the metal side, and will always fracture in the area where the CF on the CFRP material side is concentrated (Patent Document 7).

[0007] Ultimately, improving the NAT treatment method described above for each metal material and making technical improvements to increase the adhesion strength to approximately 60 MPa or more when using epoxy adhesives would be technically meaningless, since the adhesive strength between the CFRP material and the cured epoxy adhesive would be approximately 40 MPa, or at most approximately 55-60 MPa. In particular, in the aircraft field, CFRP materials using a new type of CF with a tensile strength of approximately 6 GPa are used, so there is little point in trying to improve the NAT treatment method, which is a chemical conversion treatment for metal surfaces, and increase the adhesion strength to epoxy adhesives to approximately 40 MPa or more.

[0008] (A high-strength bonding method that overcomes the large difference in linear expansion coefficient between materials) Based on the above considerations, (1) if CFRP material and A7075Al alloy are to be directly and firmly bonded, the linear expansion coefficient of the bonding surface of the CFRP material must be 2.3 × 10 -5 K -1 (2) When CFRP and metal materials other than Al alloys are directly and firmly bonded to CFRP, the metal material with the lowest linear expansion coefficient among practical metals is Ti alloy, which is approximately 0.8 × 10 -5 K -1 Therefore, Ti alloy material should be used as the metal material. Generally, metal materials thermally shrink evenly in all directions, so in order to bring CFRP closer to the linear expansion coefficient of this Ti alloy material, CFRP material with cloth (woven) CF on the adhesive surface of the CFRP material, or CFRP material with unidirectional CF CFRP prepregs layered by rotating (crossing) them, will reduce the directionality of thermal shrinkage. The linear expansion coefficient of this CFRP plate surface is approximately 0.2 x 10 -5 K -1 The difference in linear expansion coefficient is approximately 0.6 × 10 -5 K -1 The resulting adhesion is as follows.

[0009] Based on the above conditions (1) and (2), in order to apply any material, the difference in linear expansion coefficient is approximately 0.6 × 10 -5 K -1To absorb this, (3) the thickness of the cured adhesive layer is ensured to be approximately 0.3 to 1.0 mm, and an adhesive with high heat resistance is used (Patent Document 8). That is, the above (3) uses the elastic deformation of the cured adhesive layer to absorb the thermal deformation of the materials due to the difference in linear expansion coefficients. Ultimately, the methods for absorbing deformation due to the difference in linear expansion coefficients in the bonding between a CFRP material and a metal material to be bonded thereto are the above methods (1) + (3) and (2) + (3). Even in this case, if the bonding area is large, or more accurately, if the length of the bonding surface exceeds a limit, there is a limit to how much the adhesive layer can be thickened. In other words, peeling will occur at the end of the longest part (such as the corner of the bonding surface) that expands and contracts most due to temperature shock (temperature difference). As long as there is a large and clear difference in the linear expansion coefficients between the CFRP material and the metal material, even if the cured adhesive sandwiched between them is elastic and soft, there is a limit to the shape deformation that can absorb the expansion and contraction caused by the difference in linear expansion coefficients, and this is a natural consequence.

[0010] In short, the invention proposed by the inventor of the present invention and described in Patent Document 8 (prior invention) takes into account the difference in linear expansion coefficients in the longitudinal and lateral directions in the planar direction when a CFRP material and a metal material are adhesively bonded. The thickness of the cured adhesive layer sandwiched between the two materials is set to 0.3 mm or more, utilizing the allowable elastic deformation of the cured adhesive. The elastic deformation of the cured adhesive allows the layer of cured adhesive to absorb the dimensional changes (thermal contraction) that it is forced to undergo from the top and bottom (both sides). In a composite bonding CFRP and a metal material, the cured adhesive is assumed to have a bonding area of ​​5 cm square and a thickness of 1 mm, with one side being an A7075 Al alloy thick plate and the other side being a CFRP thick plate obtained by laminating and curing multiple layers of unidirectional CFRP prepreg. In this composite, the linear expansion coefficient of the Al alloy side is 2.3 × 10 -5 K -1 The linear expansion coefficient of the CFRP thick plate surface is approximately 0.1 × 10 in the longitudinal direction. -5 K -1 , in the width direction, about (7~8) x 10 -5 K -1(The linear expansion coefficient of the matrix resin, which is an epoxy adhesive). Regardless of whether this average linear expansion coefficient of CFRP has any physical significance in adhesion, the average is 3.5 x 10 -5 K -1 In other words, even when CFRP thick plates are flat, there is a large difference in the linear expansion coefficient depending on the direction of the CF. However, when looking at the difference in linear expansion coefficient with Al alloy materials, the CFRP thick plate has an average value of 3.5 x 10 -5 K -1 When using this, the difference in linear expansion coefficient with Al alloys becomes surprisingly small.

[0011] (Calculation example of how the adhesive cured layer deforms due to the linear expansion coefficient) Figure 6(a) shows an example of a composite bonded to CFRP and metal material. Figures 6(b) and 6(c) are schematic diagrams of calculated changes in the shape of the cured adhesive layer of this composite when it hardens and cools. Figure 6(b) assumes that when a one-component epoxy adhesive is heated and cured at 150°C, the thickness of the cured adhesive is 1.00 mm upon curing, and the adhesive surface is a square with a side length of 5.000 cm. At 150°C, the cured adhesive is a thin cube with a side length of 5.000 cm (50.00 mm) on the top and bottom surfaces, and a thickness of 1.00 mm. When this composite is cooled to -50°C, the temperature drops by 200°C, and the top surface of the cured adhesive (the Al alloy side in Figure 6(a)) is assumed to shrink evenly because it is a metal material, resulting in a shrinkage of 5.000 cm x (2.3 x 10 -5 K -1 ) × 200°C = 0.023 cm (0.23 mm), resulting in a square with a side of 49.977 cm. On the other hand, the surface in the direction of the fiber in the CF direction on the bottom surface (the thick CFRP plate side in Figure 6(a)) is 5.000 cm × (0.1 × 10 -5 K -1 ) × 200℃ = 0.001cm (0.01mm), which is 4.999cm. In the direction perpendicular to the fiber direction in the CF direction, it is 5.000cm × (7 × 10 -5 K -1) × 200°C = 0.023 cm (0.23 mm), resulting in a side length of 4.977 cm (Figure 6(c)). In short, the shape shown in Figure 6(b) is the shape of the adhesive cured at 150°C, and when the temperature is lowered by 200°C to -50°C, the shape of this adhesive cured product becomes the shape shown in Figure 6(c). At -50°C, the Al alloy side on the top surface, being a metal, shrinks evenly to 4.977 cm square. In contrast, the side of the CFRP side on the bottom surface, in the direction of the CF, remains almost unchanged at 4.999 cm. However, in the direction perpendicular to the CF direction, the side is 4.977 cm, and due to the large influence of the matrix resin, only one side has shrunk significantly to 4.977 cm.

[0012] To verify whether the modeled adhesive cured material reflects actual behavior, a 3,000-cycle heating and cooling test was conducted. For example, the durability of the cured adhesive, consisting of the epoxy adhesive in this example, determined whether it could continue to exist without fracture. This determined the durability of the composite, which adhesively holds the CFRP thick plate and the A7075Al alloy thick plate together. The assumed cured adhesive in this example does not contain short-fiber reinforcing fibers such as glass fiber (GF). The strong chemical cross-linking provides a reasonable degree of hardness, but it also possesses a soft, elastic nature. Its thickness was approximately 1.00 mm. Figure 6(b) shows the shape after heating and curing at 150°C. This shape was transformed to Figure 6(c) upon cooling to -50°C. The most stretched edges were the corners (diagonal lines) of the cured adhesive. These corners were 1.00 mm at +150°C, but stretched to 1.03 mm at -50°C. It was determined that a change in length of this magnitude would not cause destruction even if a forced change in shape was applied from the outside. Specifically, a demonstration experiment was required to verify that no abnormalities occurred by subjecting the composite to a temperature shock test of 3,000 cycles at -50°C / +150°C.

[0013] However, the present inventors have already conducted such experimental tests, demonstrated good results, and have already proposed and applied for a patent (Patent Document 8). In short, based on a consideration of the lines (diagonal lines) at the four corners of the cured adhesive product, the present inventors have proposed that when using a high-strength adhesive technology such as the NAT technology proposed by the present inventors and described above, in order to bond two materials with a large difference in linear expansion coefficient with an adhesive and to create an adhesive couple (composite) that can withstand a large temperature shock test with several thousand cycles, it is necessary that the thickness of the cured adhesive layer be less than 1 mm (the proposal in Patent Document 8 calls for an adhesive structure with a thickness of 0.3 to 1.0 mm).

[0014] (Use of the injection joining technology of the prior invention) However, the composite manufacturing method of the present invention is not an invention that focuses on the adhesively cured product obtained by bonding as in the above-mentioned prior invention (Patent Document 8), nor is it an invention that focuses on a joining technology using an adhesive. In other words, the present invention is another invention by the present inventors, namely, an invention that aims to manufacture a composite of CFRTP (carbon fiber reinforced thermoplastic resin) and a metal material by injection joining, which has good productivity and mass production properties, and improves the laminate structure of the composite. In other words, the composite manufacturing method of the present invention utilizes inventions related to injection joining technology in Patent Document 9 and two other patents (Patent Documents 10 and 11 (prior inventions) etc.). Injection joining technologies already proposed and named by the present inventors include "NMT (short for Nano molding technology)" and "SNMT (short for Special Nano molding technology)" (described below), and the present invention utilizes these two inventions. The present invention relates to composites integrating various practical metal materials with CFRP (narrowly defined) or CFRTP, and to a manufacturing method for the same. The two materials are integrated using injection joining technology, for example, using a polyamide-based resin, "CM3506G50" (manufactured by Toray Industries, Inc., headquartered in Tokyo, Japan). The resulting integrated product has a high shear bond strength of approximately 50-65 MPa between the metal material and the injection-molded resin material. In other words, unless a heat-resistant one-component epoxy adhesive is used for the bonded pair, a shear bond strength of the 60 MPa level cannot be achieved, and shear bond strengths of the 30 MPa range cannot be achieved even at 150°C. However, it has been found that the use of polyamide-based resins or PEEK-based resins for injection joining achieves the same level of joint strength between the metal material and the injection-molded resin material, i.e., the shear bond strength between the metal and resin in the injection-molded product. Therefore, we realized that if we use SNMT, the best injection joining technology, and use injected resin instead of adhesive, that is, an injection joining technology for joining two materials in which two materials are inserted into an injection molding die and resin is injected into a gap of several millimeters between the two materials, we can obtain a joined structure similar to the adhesive cured product described above, and this is the starting point of this invention.

[0015] [Bonding strength of composites of CFRP or CFRTP and metal materials] The inventions described in Patent Documents 10 and 11, which use the proposed injection joining technology to achieve strong bonding between two materials, i.e., CFRP or CFRTP and metal, cannot be used unless both materials are metal. In other words, it is not possible to obtain an injection-joined composite with a shear bond strength of approximately 50 to 65 MPa using CFRP and injection joining resins such as the polyamide-based resin "CM3506G50" or PEEK-based resin. In other words, when directly joining a non-metallic CFRP material to a metal material, the injection joining method cannot be used to bond two materials. Experiments have shown that no bonding occurs at all. The same is true for CFRP materials (commonly referred to as CFRTP materials) that use various thermoplastic resins as the matrix resin. The injection joining method, which directly joins CFRTP materials to metal materials, does not achieve the desired bonding strength. Therefore, first, the CFRP material and high-strength Al alloy thin plate are bonded together using the adhesive bonding technology "NAT" that uses a heat-resistant one-component epoxy adhesive to create a CFRP material with an Al alloy thin plate. To briefly explain this technology, the linear expansion coefficient of these two materials is 0.2 x 10 for CFRP. -5 K -1 , and 2.3 × 10 for Al alloys -5 K -1 The difference is 2.1 × 10 -5 K -1 If both parts are made of thick plate material, the complete bonding condition for a one-component epoxy adhesive is 150-170°C, and when this bonded pair (composite) is allowed to cool to room temperature, large internal stresses in the direction of fracture will occur in the cured adhesive layer. Therefore, although an bonded pair (composite) allowed to cool to room temperature will appear unchanged to the naked eye, if the shape of the bonded pair is as shown in Figure 4, simply lowering the temperature will cause cracks to form in the cured adhesive layer, and the shear bond strength obtained by tensile fracture will be dramatically weaker, at around 10-20 MPa.

[0016] However, what is technically interesting is that if the CFRP material is a 3-10 mm thick plate and one side is a 0.5 mm thick A6061Al alloy, the NAT bond described above will have a shear bond strength of approximately 38-40 MPa or approximately 55-58 MPa. If the CFRP material in question uses a high-strength CF with a tensile strength approaching 6 GPa, the shear bond strength will exceed the above values, reaching approximately 38-40 MPa. If a CFRP with a tensile strength in the 3 GPa range is used, the shear bond strength will be approximately 55-58 MPa. This is unavoidable, since the bond strength is determined by the strength of the CF used. However, if the adhesive strength of the thin metal plate is strong, its temperature-dependent expansion and contraction will follow the changes in the thick plate (thermal contraction). Therefore, the adhesive strength between the metal plate and the CFRP plate in a CFRP plate with a thin metal plate is not significantly affected by a large difference in linear expansion coefficients. On the other hand, the present inventors have basically proposed an integrated composite of metal and resin using a polyamide resin "CM3506G50 (manufactured by Toray Industries, Inc. (headquarters: Tokyo, Japan))" that is heat resistant and does not emit toxic gases even if involved in a fire accident, not only for Al alloys but for all high-strength metals, and PAEK resins such as PEEK.

[0017] The chemical conversion treatment disclosed therein provides a bond strength and shear bond strength between metal and resin in injection-bonded products of 50-64 MPa, which is not significantly different from the maximum shear bond strength of 60 MPa achieved between metals using adhesive bonding technology NAT.The present inventors have also proposed a laminated composite using an adhesive, consisting of three layers: one made of FRP material and one made of structural metal material at both ends, and an aluminum alloy layer in the middle, so that it can withstand temperature shock even if there is a difference in linear expansion coefficient between the components (Patent Document 12). [Prior art documents] [Patent documents]

[0018] [Patent Document 1] WO2008 / 114669 [Patent Document 2] WO2008 / 133096 [Patent Document 3] WO2008 / 133296 [Patent Document 4] WO2008 / 126812 [Patent Document 5] WO2008 / 133030 [Patent Document 6] WO2008 / 146833 [Patent Document 7] Patent Publication No. 2011-073191 [Patent Document 8] Patent application 2021-040744 [Patent Document 9] Patent Publication No. 2016-150547 [Patent Document 10] Patent application 2020-176274 [Patent Document 11] Patent application 2021-095385 [Patent Document 12] Patent application 2020-018513 Summary of the Invention [Problem to be solved by the invention]

[0019] Given the above background, it can be said that the various conventional methods proposed for bonding composites of CFRP and other FRP with non-aluminum metal materials, aluminum alloys, etc. have mainly used adhesives, resulting in low productivity. In the manufacture of composites of CFRP and metal materials, there is a strong demand for a bonding method and structure that is highly productive and can obtain strong adhesive strength. An object of the present invention is to provide a method for producing a composite of CFRP and metal material, in which productivity is increased by fixing a high-strength metal material and a CFRP material by injection molding, and to provide such a composite. Another object of the present invention is to provide a method for manufacturing a composite of CFRP and metal material, in which the CFRP and metal material are bonded together using a thermoplastic resin that is highly versatile and harmless to combustion, and to provide such a composite. Yet another object of the present invention is to provide a method for producing a composite of CFRP and metal material in which CFRP and metal material are bonded together using a versatile thermoplastic resin with high thermal shock resistance, and to provide such a composite. A further object of the present invention is to provide a method for producing a composite of CFRPs and metal materials, which can firmly bond CFRP, CFRTP and various commonly used metal materials, and the composite. [Means for solving the problem]

[0020] The method for producing a composite of CFRP and metal material according to the present invention 1 includes the steps of: an Al alloy thin plate chemical conversion treatment process for chemically treating one surface of an Al alloy thin plate having a thickness of 0.3 to 0.8 mm for adhesion; a bonding step of bonding one surface of the Al alloy thin plate to a surface of a CFRP material to obtain a CFRP material with an Al alloy thin plate; a chemical conversion treatment step for injection joining in which a surface of a metal material and the other surface of the Al alloy thin plate are chemically treated for injection joining; an inserting step of inserting the metal material into an injection molding die with a gap of 1.0 to 5.0 mm between the surface of the metal material and the other surface of the Al alloy thin plate; and an injection step of injecting a heat-resistant crystalline thermoplastic resin for injection joining into the gap.

[0021] The method for producing a composite of CFRP and metal material according to the present invention 2 is as follows: A crystalline thermoplastic resin is injected onto one surface of an aluminum alloy thin plate with a thickness of 0.3 to 0.8 mm and fixed. A resin plate with an Al alloy thin plate is obtained. a metal sheet-attached resin sheet fixing step; A step of preparing a CFRTP sheet material having a main component resin contained in the crystalline thermoplastic resin as a matrix resin; a hot press lamination step in which one surface of the CFRTP plate material and the resin plate with the Al alloy thin plate are overlapped and brought into contact with each other, and then inserted into a hot press mold for fusion lamination to obtain a CFRTP thick plate material with the Al alloy thin plate; a chemical conversion treatment step for injection joining in which a surface of a metal material and the other surface of the Al alloy thin plate are chemically treated for injection joining; the surface of the metal material and the other surface of the Al alloy thin plate an inserting step of inserting the molded product into an injection molding die with a gap of 1.0 to 5.0 mm between the molded product and the molded product; The gap is provided with a heat-resistant material for injection joining. The aforementioned and an injection step of injecting a crystalline thermoplastic resin.

[0022] The method for producing a composite of CFRP and a metal material according to the third aspect of the present invention is the same as that according to the first aspect of the present invention, The bonding step includes: As a pretreatment, a chemical conversion treatment step for adhesive bonding is performed on one surface of the Al alloy thin plate; a coating step of coating the one surface with a heat-resistant one-component epoxy adhesive; an Al alloy thin plate lamination step of laminating the one surface of the Al alloy thin plate on a surface of a laminate obtained by laminating CFRP prepregs; an adhesive curing process in which the laminate of the CFRP prepreg and the Al alloy thin plate is heated in an environment reduced in pressure to atmospheric pressure or less to bond and harden the laminate; The other surface of the Al alloy thin plate in the injection joining chemical conversion treatment step and the chemically treated surface of the metal material are The method is characterized by including a chemical conversion treatment step for injection joining, which is a surface treatment for adjusting the surface shape, chemical reactivity or surface properties for injection joining.

[0023] The method for producing a composite body in which a CFRP material and a metal material are integrated according to the fourth aspect of the present invention is the method for producing a composite body in which a CFRP material and a metal material are integrated according to the second aspect of the present invention, The crystalline thermoplastic resin and the CFRTP board material The matrix resin contained in the above is a similar thermoplastic resin composition, and is characterized by being a resin composition whose main component is a resin that can be completely mixed when melted.

[0024] The method for producing a composite body in which a CFRP and a metal material are integrated according to the fifth invention is the method according to any one of the first to fourth inventions, The Al alloy thin plate is one selected from A5052, A5083, and A6061 as specified by Japanese Industrial Standards. The method for producing a composite body in which CFRP and a metal material are integrated according to the sixth aspect of the present invention is the method for producing a composite body in accordance with any one of the first to fourth aspects of the present invention, The metal material is characterized in that it is one selected from Al alloys A2014, A2017, A2024, and A7075 specified by Japanese Industrial Standards, or one selected from general steel, stainless steel, and 64Ti alloy.

[0025] The method for producing a composite body in which a CFRP and a metal material are integrated according to the seventh invention is the same as any one of the first to fourth inventions, The crystalline thermoplastic resin is one selected from PPS-based resins, polyamide-based resins, and PAEK-based resins including PEEK. The method for producing a composite body in which a CFRP and a metal material are integrated according to the eighth aspect of the present invention is the same as the seventh aspect of the present invention, except that: The PPS resin does not contain GF or the GF content is 20% by weight or less, and the polyamide resin does not contain GF or the GF content is 20% by weight or less. of The content is 33.3% by weight or less, and the PEEK or PAEK resin is either GF-free or a mixed resin of the PEEK and polyetherimide (PEI) resin in a mass ratio of 95:5 to 85:15.

[0026] The method for producing a composite body in which a CFRP and a metal material are integrated according to the ninth aspect of the present invention is the method according to any one of the first to eighth aspects of the present invention, The chemical conversion treatment of the Al alloy thin plate and the metal material is characterized in that the water-soluble amine compound is triethanolamine or EDTA (4Na). The method for producing a composite in which CFRP and a metal material are integrated according to Inventions 1 to 9, is a composite in which CFRP and a metal material are integrated, produced by the method for producing a composite according to Inventions 1 to 9.

[0027] The components constituting the composite of the present invention and the method for producing the composite will now be outlined. [CFRP: CFRP or CFRTP] The CFRPs constituting the composite of the present invention, i.e., both CFRP and CFRTP in the narrow sense, are carbon fiber reinforced plastics (CFRPs) and are long fiber reinforced plastic solids obtained by resin-reinforcing bundles or fabrics of carbon fiber (CF). In the present invention, CFRP refers to a matrix (base material) made of a thermosetting resin such as epoxy resin, while CFRTP (Carbon Fiber Reinforced Thermoplastics) refers to a matrix resin made of a thermoplastic resin such as polyamide. In the present invention, CFRP includes both CFRTP and CFRP in the narrow sense. The CFRP or CFRTP used in the present invention is not special but is versatile and commercially available. The CFs arranged in the matrix resin may be aligned in one direction, layered by crossing unidirectional CFs, or woven into a fabric, and should be selected depending on the location where the composite of the present invention will be used. The matrix resin of the CFRP or CFRTP is preferably a commonly used thermosetting resin, but any resin may be used.

[0028] [Al alloy thin plate] The Al alloy thin plate constituting the composite of the present invention is surface-bonded to the CFRP or CFRTP by adhesive bonding or injection bonding. The Al alloy thin plate has a thickness of 0.3 to 0.8 mm, and its surface is treated with a predetermined surface roughness for adhesion or bonding, such as by chemical conversion treatment, prior to adhesive bonding or injection bonding. Because of its thin thickness, the Al alloy thin plate of the present invention follows the thermal expansion and contraction of the CFRP or CFRTP and transmits stress applied to the Al alloy thin plate to the CFRP or CFRTP. The Al alloy thin plate also follows the difference in expansion and contraction in the perpendicular direction within the bonding surface between the CFRP or CFRTP and the Al alloy thin plate. The Al alloy thin plate material is optimally a wrought aluminum alloy specified by the Japanese Industrial Standards, specifically, one selected from the group consisting of A5052 and A5083, which are Al-Mg alloys, and A6061, which is an Al-Mg-Si alloy.

[0029] [Metal material] The metal material constituting the composite of the present invention is integrated with CFRP or CFRTP, and the CFRP or CFRTP is bonded to the CFRP or CFRTP via the above-mentioned Al alloy thin plate and highly crystalline thermoplastic resin. The metal material may be any metal used in various machine bodies, housings, etc. Specifically, in the case of an Al alloy, a wrought aluminum alloy is preferably used. Specifically, one selected from Al alloys specified by the Japanese Industrial Standards (JIS) such as A2014, A2017, and A2024, which are Al-Cu-Mg alloys, and A7075, which is an Al-Zn-Mg alloy, is used. Alternatively, various general steels, stainless steels, 64Ti alloys, etc. may be used. Because the metal material is bonded to the highly crystalline thermoplastic resin to form the composite, the surface of the metal material to be bonded to the highly crystalline thermoplastic resin is pre-treated with a chemical conversion coating prior to bonding to increase bonding strength.

[0030] [Highly crystalline thermoplastic resin] The highly crystalline thermoplastic resin constituting the composite of the present invention serves as a member for bonding the Al alloy thin plate and the metal material to each other, forming a thin layer. Bonding the Al alloy thin plate and the metal material with the highly crystalline thermoplastic resin is performed by insert molding. That is, a CFRP material with an Al alloy thin plate bonded thereto (CFRP material or CFRTP material) and a metal material are inserted into an injection molding die, and the highly crystalline thermoplastic resin is injected into the gap to form a composite. Therefore, the highly crystalline thermoplastic resin serves as a bonding material between the Al alloy thin plate and the metal material, an adhesive, and a laminating material. The highly crystalline thermoplastic resin is preferably one selected from PPS-based resins, polyamide-based resins, and PAEK-based resins, including PEEK. In the case of PPS-based resins, those that do not contain glass fiber (GF) or have a GF content of 20% by weight or less are preferred. In the case of polyamide-based resins, those that do not contain GF or have a GF content of 33.3% by weight or less are preferred. In the case of polyetheretherketone (PEEK) resins, those that do not contain GF can be used, and mixed resins that show a mass ratio of polyetheretherketone and polyetherimide (PEI) resins of 95:5 to 85:15 have better adhesive strength than resins using PEEK alone.

[0031] [Adhesion of CFRP material and thin aluminum alloy plate] In the manufacture of the composite of the present invention, an Al alloy thin plate is first bonded to a CFRP or CFRTP material. The CFRP material and the Al alloy thin plate are bonded by adhesion, but before bonding, the bonding surface of the Al alloy thin plate must be optimized by chemical conversion treatment. Since this chemical conversion treatment method is not the gist of the present invention and is a well-known technique, a detailed description thereof will be omitted. Chemical conversion treatment is performed, for example, by the method described in Patent Document 1 proposed by the inventors of the present invention or Experimental Example 8 described below. A heat-resistant one-component epoxy adhesive is applied to the surface of the Al alloy thin plate that has been chemically treated for bonding. An Al alloy thin plate coated with this heat-resistant one-component epoxy adhesive is then laminated onto the surface of a laminate consisting of a CFRP prepreg. The laminate consisting of the CFRP prepreg and the Al alloy thin plate is heated in an environment reduced to or below atmospheric pressure to bond and harden. This series of bonding operations produces a CFRP with an Al alloy thin plate.

[0032] [Bonding of CFRTP and Al alloy thin plate] The bonding of the CFRTP material and the thin Al alloy sheet is performed in two steps (see Figures 9 and 10). In the first step, a resin plate with an Al alloy thin sheet is prepared. Prior to this preparation, the matrix resin of the CFRTP material is bonded to one surface of the thin Al alloy sheet by injection molding. Prior to this bonding, the surface of the thin Al alloy sheet is subjected to a chemical conversion treatment. This chemical conversion treatment is performed, for example, by a method proposed by the inventors of the present invention, such as that described in Patent Document 10, or by Experimental Example 2 (SNMT (Special Nano molding technology)) described below, although not limited to this chemical conversion treatment. In the second step, the CFRTP material is bonded to the resin plate with the thin Al alloy sheet by heating and pressing. The resin portion of the resin plate with the thin Al alloy sheet and the CFRTP material are laminated, and then heated and pressed, preferably under vacuum, to a temperature above the softening temperature of the resin material to bond the matrix resin of the CFRTP material to the resin portion of the resin plate with the thin Al alloy sheet by thermal fusion.

[0033] [Adhesion of metal materials and thin aluminum alloy plates] As described above, the highly crystalline thermoplastic resin constituting the composite of the present invention is a component for bonding the Al alloy thin plate and the metal material together. The metal material and the Al alloy thin plate are bonded together by injecting the highly crystalline thermoplastic resin described above. The surfaces of the metal material and the Al alloy thin plate must be optimally chemically treated to strengthen the bond with the highly crystalline thermoplastic resin. While known techniques already proposed and disclosed by the inventors of the present invention may be used, the SNMT treatment described below by the inventors is optimal (see Experimental Examples 2, 3, 4, 5, 6, and 7 described below). [Effects of the Invention]

[0034] The CFRP and metal composite of the present invention is a strong integration of CFRP or CFRTP material with various high-strength metal materials, including aluminum alloys such as duralumin, steel, titanium alloys, and stainless steel, even if there is a large difference in the linear expansion coefficients of the materials, and is therefore able to withstand thermal shock. The composite of the present invention can be used for lightweight, strong airframes and main bodies of various machines, such as aircraft, thereby contributing to resource and energy conservation. The manufacturing method for the composite of the present invention uses injection joining as its main technology, making it highly productive, easily automatable, and suitable for mass production. [Brief explanation of the drawings]

[0035] [Figure 1] Figure 1 shows a test piece that is an injection-bonded product for measuring shear bond strength. [Figure 2] Figure 2 shows a test piece of an injection-bonded product for measuring tensile strength. [Figure 3] Figure 3 shows an auxiliary jig for fixing the test piece when measuring the shear bond strength. [Figure 4] Figure 4 shows test pieces for measuring shear bond strength, where Figure 4(a) shows a test piece for measuring shear bond strength between metal pieces, and Figure 4(b) shows a test piece for measuring shear bond strength between CFRP pieces. [Figure 5] Figure 5 shows a test piece made of metal pieces, used to measure the tensile adhesive strength between metals. [Figure 6] Figure 6(a) shows an example of a composite bonded to CFRP and metal material, Figure 6(b) is a schematic diagram of the adhesive cured product of the composite when heated to a temperature of 150°C and hardened, and Figure 6(c) is a schematic diagram of the adhesive cured product when cooled to -50°C.

[0036] [Figure 7] Figure 7 shows a test method for measuring the shear adhesive strength of a test piece in a thermal fusion bonding process in which an injection bonding resin is injected between two types of thick metal plate pieces. [Figure 8] FIG. 8 is a schematic diagram showing an example of the arrangement when both a CFRP thick plate with a surface-treated Al alloy thin plate and a surface-treated high-strength metal thick plate piece are inserted into an injection joining die. [Figure 9] FIG. 9 is a schematic diagram showing a process of inserting an Al alloy thin plate into a mold for injection joining, and injecting a crystalline thermoplastic resin for injection joining to obtain a resin plate-like product with an Al alloy thin plate. [Figure 10] FIG. 10 is a schematic diagram showing the thermal fusion bonding of a resin plate with an Al alloy thin plate and a CFRTP material using a heat press. [Figure 11] FIG. 11 is a structural diagram showing an example of the shape of a composite of a CFRP material with an Al alloy thin plate and a high-strength metal material. [Figure 12] FIG. 12 is a structural diagram showing an example in which the composites of FIG. 11 are connected to form a backbone structure of a structure. BEST MODE FOR CARRYING OUT THE INVENTION

[0037] [Manufacturing method for composites of CFRP with Al alloy thin plate and metal material] Hereinafter, a method for manufacturing a composite of CFRP and metal material and an embodiment of the composite according to the present invention will be described. The composite is an example in which a CFRP with an Al alloy plate is joined to a 64Ti alloy plate, which is a high-strength thick metal plate. FIG. 8 is a schematic diagram showing the cross section of an injection molding die used to manufacture the composite. This injection molding die is used to insert and integrate both a CFRP with an Al alloy plate and a 64Ti alloy plate. In the CFRP with an Al alloy plate, the surface of the Al alloy plate is chemically treated (the "SNMT treatment" in Experimental Example 2, which will be described later), and similarly, the surface of the 64Ti alloy plate, which is a high-strength thick metal plate, is chemically treated (the "SNMT treatment" in Experimental Examples 3 or 4, which will be described later). To manufacture the CFRP with an Al alloy plate, one side of the Al alloy plate is chemically treated to optimize adhesive strength (the "NAT" treatment in Experimental Example 8, which will be described later), and then this chemically treated surface is bonded to one side of the CFRP (the bonding treatment in Experimental Example 9). From the viewpoint of increasing the bonding strength, it is preferable to use a one-component epoxy adhesive that is similar to the main component of the matrix resin of CFRP and that bonds by heating. The detailed bonding method will be explained in the experimental example below.

[0038] The 64Ti alloy piece was machined to a desired shape to suit its intended use, and one side of the piece was subjected to the aforementioned chemical conversion treatment to optimize the surface for injection joining (Experimental Examples 3 and 4, described below). Similarly, the surface of the Al alloy thin plate of the CFRP thick plate with the Al alloy thin plate, which faces the resin to be joined, was also subjected to the aforementioned chemical conversion treatment to optimize the surface for injection joining (Experimental Example 2). As shown in FIG. 8 , the CFRP thick plate with the Al alloy thin plate and the 64Ti alloy piece were inserted into an injection mold with a predetermined gap between them. A thermoplastic synthetic resin composition, such as PPS resin, polyamide resin, or PAEK resin (including PEEK), was then injected into the gap to produce a composite in which the CFRP and metal material were firmly integrated. The CFRP and metal composite of this embodiment uses CFRP with a thermosetting resin matrix. However, instead of CFRP, a CFRTP with a thermoplastic synthetic resin matrix may be used. We will explain a composite using this CFRTP, in which a resin plate with an Al alloy thin plate is bonded to the CFRTP.

[0039] [Manufacturing method for composites of CFRTP with Al alloy thin plate and metal material] To manufacture a composite of a CFRTP with an Al alloy thin plate and a metal material, a resin plate with an Al alloy thin plate must first be manufactured. Figures 9 and 10 are schematic diagrams illustrating a method for manufacturing a resin plate with an Al alloy thin plate. A chemical conversion treatment is performed on one side of the Al alloy thin plate to firmly bond the resin (e.g., Experimental Example 1 or 2). As shown in Figure 9, an Al alloy thin plate material with a chemical conversion treatment surface is inserted into an injection molding die, and a thermoplastic resin, such as a PEEK-based resin, is injected onto the chemically treated surface to form a thin layer on the surface of the Al alloy thin plate. This injection joining process results in a thermoplastic resin plate with an Al alloy thin plate. Furthermore, a vacuum hot press molding die is used to manufacture a composite in which a CFRTP thick plate is integrally bonded to a thermoplastic resin plate with an Al alloy thin plate. Figure 10 is a cross-sectional view illustrating the concept of the vacuum hot press molding die. To manufacture the composite, a CFRTP thick plate with a PEEK-based resin matrix, for example, is inserted into the vacuum hot press molding die, and the thermoplastic resin plate with an Al alloy thin plate is stacked on top of it with the resin side facing down. A heating and pressing jig is placed on top of this, and heating and pressing are performed using an electric heater. Simultaneously with this heating and pressing, the air inside the vacuum hot press mold is sucked out from the heat-sealed bonding surface, which is the joining surface, to strengthen the bond. The heating temperature is set near the softening temperature of the PEEK-based resin. As described above, by using heating and pressing pressure, a CFRTP thick plate with an Al alloy thin plate is manufactured, as shown in Figure 10. A composite of a CFRTP thick plate and metal material is manufactured in the same way as shown in Figure 8, by bonding the CFRTP thick plate with an Al alloy thin plate and the metal material with a highly crystalline thermoplastic resin inside an injection molding mold (not shown). Through these processes, a composite of a CFRTP thick plate with an Al alloy thin plate and metal material is manufactured.

[0040] [Structural example of the complex of the present invention] FIG. 11 shows an example of a joint structure of CFRP, a metal material, and a composite obtained by the manufacturing method described in FIG. 8 . This composite is made by joining a 64Ti alloy plate to a CFRP structure for mechanical fastening, drilling bolt holes in the 64Ti alloy plate, and fastening with bolts and nuts. FIG. 12 is a conceptual diagram showing an example of a structure using this composite as a large structure. CFRP is long, flexible, and strong due to its characteristics, and this example shows its use as the basic structure that corresponds to the spine of an aircraft fuselage. Two or more elongated CFRP strands are arranged and fixed with mechanical connecting fixtures to form a spine structure. The ends of this spine structure are mechanically fastened with bolts and nuts, as shown in FIG. 11 . As can be seen from the above example structure, the CFRP and metal composite of the present invention can form a strong, integrated object while taking advantage of the mechanical strength properties of each material, even if there is a difference in thermal expansion coefficient. Although not shown, CFRTP material can also be used as a structural material. [Example]

[0041] Examples of the present invention will be described in detail below. (a) Measurement of injection bonding strength The shear bond strength referred to in this invention is the shear fracture value when the test piece shown in Figure 1 is tensile fractured using a testing machine. This fracture bond strength is the shear strength when the metal and resin of the test piece are bonded (bonded by injection molding). The tensile testing machine used was an "AG-500N / 1kN (manufactured by Shimadzu Corporation, headquartered in Kyoto, Japan)," and measurements were taken at a tensile speed of 10 mm / min. Figure 3 shows the auxiliary jig used in this measurement. These measurement methods comply with ISO 19095. Similarly, the test piece shown in Figure 2 is used to measure the tensile bond strength between the metal and resin parts of an injection-bonded product. This measurement method complies with ISO 19095.

[0042] (b) Measurement of adhesive bond strength The test piece shown in Figure 4(a) is an adhesive test piece used in the experiments of the present invention to measure the adhesive strength between metal pieces, and is used to measure the shear bond strength between metals. As shown in Figure 4(b), if a CFRP piece is used instead of this metal piece, the shear bond strength between CFRP can be measured. Similarly, the test piece shown in Figure 5 is used to measure the tensile bond strength between metal pieces. This measurement method complies with ISO 19095. These testers are the tensile testers mentioned above, and measurements were similarly performed at a tensile speed of 10 mm / min. (c) Temperature shock cycle test The above specimens were subjected to a temperature shock cycle test. The temperature shock cycle tester used was the "Small Thermal Shock Tester TSE-12-A (manufactured by Espec Corporation, headquartered in Osaka, Japan)." The standard temperature shock cycle test conditions were a cold chamber temperature of -50°C, a hot chamber temperature of +150°C, a 25-minute stay time in each chamber, and approximately 5 minutes of movement between chambers. The tester itself was placed in a room constantly regulated at 27°C, and automatic operation was performed by periodically raising the cold chamber temperature to room temperature to allow ice to melt naturally. However, to prevent ice buildup at high humidity, which can occur even with this automatic operation cycle, the tester was shut down on weekends and on Japanese holidays such as New Year's, May, and August to prevent damage to the tester.

[0043] The surface treatment and manufacturing method of each test piece described above will be explained below as experimental examples. [Experimental example] Surface treatment of each material [Experimental Example 1] Surface treatment of A7075 Al alloy (referred to as "SNMT treatment" in the present invention) A 1.5 mm thick A7075 aluminum alloy plate was purchased and machined to the required shape to obtain aluminum alloy flakes. An immersion tank was filled with an aqueous solution containing 10.0% aluminum degreaser "NA-6" (manufactured by Meltex Inc., headquartered in Tokyo, Japan) at a temperature of 60°C. The aluminum alloy flakes were immersed for 5 minutes and then rinsed with public tap water (Ota City, Gunma Prefecture). A separate tank was filled with a 10.0% aqueous caustic soda solution at a temperature of 40°C. The alloy flakes were immersed for 1 minute and then rinsed with water. A separate tank was filled with an aqueous solution containing 1.0% aluminum chloride hydrate and 5.0% hydrochloric acid at a temperature of 40°C. The alloy flakes were immersed for 2 minutes and then rinsed with water. A separate tank was filled with an aqueous solution containing 2.0% acid ammonium fluoride and 10.0% sulfuric acid at a temperature of 40°C. The alloy flakes were immersed for 1 minute and then rinsed with water. Next, in another tank, a 1.5% caustic soda solution at 40°C was prepared, and the alloy pieces were immersed in this for 2 minutes, followed by rinsing with water. Next, in another tank, a 3.0% nitric acid solution at 40°C was prepared, and the Al alloy pieces were immersed in this for 1 minute, followed by rinsing with water. Next, in another tank, a 3.5% hydrazine hydrate solution at 60°C was prepared, and the Al alloy pieces were immersed in this for 1 minute, and then in another tank, a 0.5% hydrazine hydrate solution at 33°C for 2.5 minutes, followed by rinsing with water. Next, in another tank, the pieces were immersed in a 1.5% hydrogen peroxide solution for 1 minute, followed by thorough rinsing with water. Next, in another tank, the pieces were immersed in a 0.2% triethanolamine solution at 40°C for 20 minutes, followed by rinsing with a 50 ppm triethanolamine solution in a separate tank. These Al alloy pieces were dried in a hot air dryer set at a temperature of 67°C for 15 minutes, and then wrapped together in clean aluminum foil and stored.

[0044] [Experimental Example 2] Surface treatment of A6061 Al alloy (SNMT treatment) A 1.5 mm thick A6061 aluminum alloy plate was purchased and machined to the required shape to obtain aluminum alloy pieces. An immersion tank contained an aqueous solution containing 10.0% of the aluminum degreaser "NA-6" at 60°C. The aluminum alloy pieces were immersed for 5 minutes and then rinsed with public tap water. A separate tank contained a 10.0% aqueous caustic soda solution at 40°C. The aluminum alloy pieces were immersed for 1 minute and then rinsed. A separate tank contained an aqueous solution containing 1.0% aluminum chloride hydrate and 5.0% hydrochloric acid at 40°C. The aluminum alloy pieces were immersed for 1 minute and then rinsed. A separate tank contained an aqueous solution containing 2.0% ammonium fluoride and 10% sulfuric acid at 40°C. The aluminum alloy pieces were immersed for 1 minute and then rinsed. Next, in another tank, a 1.5% caustic soda solution at 40°C was prepared, and the Al alloy pieces were immersed in this for 2 minutes, followed by rinsing with water. Next, in another tank, a 3.0% nitric acid solution at 40°C was prepared, and the Al alloy pieces were immersed in this for 1.5 minutes, followed by rinsing with water. Next, in another tank, a 3.5% hydrazine hydrate solution at 60°C was prepared, and the Al alloy pieces were immersed in this for 1 minute, followed by immersion in a 0.5% hydrazine hydrate solution at 33°C for 4.5 minutes, followed by rinsing with water. Next, in another tank, the pieces were immersed in a 1.5% hydrogen peroxide solution for 1 minute, followed by thorough rinsing with water. Next, in another tank, the pieces were immersed in a 0.2% triethanolamine solution at 40°C for 20 minutes, followed by rinsing with a 50 ppm triethanolamine solution in another tank. These Al alloy pieces were dried in a hot air dryer set at a temperature of 67°C for 15 minutes, and then wrapped together in clean aluminum foil and stored.

[0045] [Experimental Example 3] Surface treatment of 64Ti alloy (SNMT treatment) A number of small pieces of 64Ti alloy measuring 45 mm x 18 mm x 1.5 mm thick were obtained and used as test pieces. An immersion tank was filled with an aqueous solution containing 10.0% of the aluminum degreaser "NA-6" at 60°C. The Ti alloy pieces were immersed for 5 minutes and then rinsed with public tap water. A separate tank was then filled with an aqueous solution containing 5% acidic ammonium fluoride at 65°C. The Ti alloy pieces were immersed for 5 minutes and then rinsed. A separate tank was then filled with a 3.0% aqueous nitric acid solution at 40°C. The Ti alloy pieces were immersed for 3 minutes and then rinsed. A separate tank was then filled with an aqueous solution containing 2.0% potassium permanganate and 3.0% caustic potash at 70°C. The Ti alloy pieces were immersed for 30 minutes and then rinsed. Next, in another tank, an aqueous solution containing 5.0% sodium chlorite and 10.0% caustic soda at a temperature of 55°C was prepared, and the Ti alloy pieces were immersed in this for 10 minutes, and then immersed in a water tank equipped with an ultrasonic vibration tip for 7 minutes to clean off any deposits. Next, in another tank, the pieces were immersed in a 0.2% triethanolamine aqueous solution at a temperature of 40°C for 30 minutes, and then washed in another tank with a 50 ppm triethanolamine aqueous solution. These Ti alloy pieces were then placed in a hot air dryer set to a temperature of 67°C for 15 minutes to dry, and then wrapped in clean aluminum foil and stored.

[0046] [Experimental Example 4] Surface treatment of 64Ti alloy (referred to as "SNMT2 treatment" in the present invention) A number of small pieces of 64Ti alloy measuring 45mm x 18mm x 1.5mm thick were obtained and used as test pieces. An immersion tank was filled with an aqueous solution containing 10% of the aluminum degreaser "NA-6" at 60°C. The Ti alloy pieces were then immersed for 5 minutes and rinsed with public tap water. A separate tank was then filled with an aqueous solution containing 5.0% acidic ammonium fluoride at 65°C. The Ti alloy pieces were then immersed for 5 minutes and rinsed. A separate tank was then filled with a 3.0% aqueous nitric acid solution at 40°C. The Ti alloy pieces were then immersed for 3 minutes and rinsed. A separate tank was then filled with an aqueous solution containing 2.0% potassium permanganate and 3.0% caustic potash at 70°C. The alloy pieces were then immersed for 30 minutes and rinsed. Next, in another tank, an aqueous solution containing 5.0% sodium chlorite and 10.0% caustic soda was prepared at a temperature of 55°C. The Ti alloy pieces were immersed in this for 10 minutes, and then immersed in a water tank equipped with an ultrasonic vibration tip for 7 minutes to clean off any deposits. Next, in another tank, the pieces were immersed in a 0.4% EDTA (4Na) aqueous solution at a temperature of 40°C for 10 minutes, and then rinsed with a 0.1% acetic acid aqueous solution in another tank. These Ti alloy pieces were placed in a hot air dryer set at a temperature of 67°C for 15 minutes to dry, and then wrapped in clean aluminum foil and stored.

[0047] [Experimental Example 5] Surface treatment of SUS304 steel (SNMT treatment) A number of small pieces of SUS304 steel measuring 45 mm x 18 mm x 1.5 mm thick were obtained and used as test specimens. An immersion tank was filled with an aqueous solution containing 10.0% of the aluminum degreaser "NA-6" at 60°C. The steel pieces were then immersed for 5 minutes and then rinsed with public tap water. A separate tank was then filled with an aqueous solution containing 1.0% acidic ammonium fluoride and 10.0% sulfuric acid at 60°C. The steel pieces were then immersed for 6 minutes and then rinsed with water. The steel pieces were then immersed for 7 minutes in a water tank equipped with an ultrasonic vibrator to remove deposits. A separate tank was filled with an aqueous solution containing 0.5% acidic ammonium fluoride and 5% sulfuric acid at 60°C. The steel pieces were then immersed for 20 minutes and then rinsed with water. A separate tank was then filled with an aqueous solution containing 3.0% nitric acid at 40°C. The steel pieces were then immersed for 3 minutes and then rinsed with water. Next, in another tank, an aqueous solution containing 5.0% sodium chlorite and 10% caustic soda was prepared and heated to 55°C. The steel pieces were immersed in this for 6 minutes and then rinsed with water. Next, in another tank, the pieces were immersed in a 1.5% hydrogen peroxide solution for 0.5 minutes and then thoroughly rinsed with water. Next, in another tank, the pieces were immersed in a 0.4% triethanolamine solution at 40°C for 30 minutes, and then washed with a 50 ppm triethanolamine solution. These steel pieces were then placed in a hot air dryer set to 67°C for 15 minutes to dry, and then wrapped in clean aluminum foil and stored.

[0048] [Experimental Example 6] Surface treatment of SUS430 steel (SNMT treatment) A number of small pieces of SUS430 steel measuring 45 mm x 18 mm x 1.5 mm thick were obtained and used as test specimens. The steel pieces were immersed in an immersion tank containing a 10.0% solution of the aluminum degreaser "NA-6" at 60°C for 5 minutes, after which they were rinsed with public tap water. Next, in a separate tank, the steel pieces were immersed in a 5.0% acidic ammonium fluoride solution at 65°C for 10 minutes, after which they were rinsed with water. Next, the steel pieces were immersed in a water tank equipped with an ultrasonic vibrator for 7 minutes to remove deposits. In another tank, an aqueous solution containing 0.5% acidic ammonium fluoride and 5% sulfuric acid at 50°C was prepared, and the steel pieces were immersed in this for 5 minutes, after which they were rinsed with water. Next, in a separate tank, a 3.0% nitric acid solution at 40°C was prepared, and the steel pieces were immersed in this for 3 minutes, after which they were rinsed with water. Next, the steel pieces were immersed in a water tank equipped with an ultrasonic vibrator for 7 minutes to remove deposits. Next, in another tank, an aqueous solution containing 2.0% potassium permanganate, 1.0% acetic acid, and 0.5% sodium acetate was prepared at 45°C. The steel pieces were immersed in this for 2 minutes and then rinsed with water. Next, in another tank, an aqueous solution containing 2.0% potassium permanganate and 3.0% caustic potash was prepared at 70°C. The steel pieces were immersed in this for 15 minutes and then rinsed with water. Next, the steel pieces were immersed in a water tank equipped with an ultrasonic vibrator for 7 minutes to remove any deposits. Next, in another tank, the steel pieces were immersed in a 1.5% hydrogen peroxide solution for 0.5 minutes and then thoroughly rinsed with water. Next, in another tank, the steel pieces were immersed in a 0.4% triethanolamine solution at 40°C for 20 minutes. Then, in another tank, they were washed with a 50 ppm triethanolamine solution. After that, the steel pieces were placed in a hot air dryer set to 67°C for 15 minutes to dry, and then wrapped in clean aluminum foil and stored.

[0049] [Experimental Example 7] Surface treatment of SPCC (SNMT treatment) A 45mm x 18mm SPCC piece was machined from a 1.6mm thick SPCC (cold-rolled steel plate) and used as a test specimen. The steel piece was immersed in an immersion bath containing a 10.0% solution of the aluminum degreaser "NA-6" at 60°C for 5 minutes, then rinsed with public tap water. The steel piece was then immersed in a separate bath containing a 5.0% acidic ammonium fluoride solution at 65°C for 25 minutes, then rinsed with water. The steel piece was then immersed in a separate bath containing a 1.0% ammonia solution and then rinsed. The steel piece was then immersed in a separate bath containing a 2.0% potassium permanganate, 1.0% acetic acid, and 0.5% sodium acetate hydrate solution at 45°C for 45 minutes, then rinsed with water. The SPCC pieces were then immersed in a separate tank containing a 2.0% potassium permanganate and 3.0% caustic soda solution at 70°C for 20 minutes and then rinsed with water. They were then immersed in a water tank equipped with an ultrasonic vibrator for 7 minutes to remove any deposits. They were then immersed in a separate tank containing a 1.5% hydrogen peroxide solution for 0.5 minutes and thoroughly rinsed with water. They were then immersed in a separate tank containing a 0.2% triethanolamine solution at 40°C for 30 minutes, and then rinsed in a separate tank containing a 50 ppm dilute triethanolamine solution. These SPCC pieces were then dried in a hot air dryer set at 67°C for 15 minutes, then wrapped in clean aluminum foil and stored.

[0050] [Experimental Example 8] Surface treatment of A6061 Al alloy (referred to as "NAT treatment" in the present invention) NAT treatment is a surface treatment method for bonding. A 1.5 mm thick A6061 aluminum alloy plate was purchased and machined to the required shape to produce aluminum alloy pieces. An immersion tank was filled with an aqueous solution containing 10.0% of the aluminum degreaser "NA-6" at 60°C. The aluminum alloy pieces were immersed for 5 minutes and then rinsed with public tap water. A separate tank was then filled with a 1.0% hydrochloric acid solution at 40°C. The aluminum alloy pieces were immersed for 1 minute and then rinsed. A separate tank was then filled with a 1.5% caustic soda solution at 40°C. The aluminum alloy pieces were immersed for 4 minutes and then rinsed. A separate tank was then filled with a 3.0% nitric acid solution at 40°C. The alloy pieces were immersed for 3 minutes and then rinsed. Next, in another tank, a 3.5% hydrazine hydrate aqueous solution at 60°C was prepared, and the pieces were immersed in this for 2 minutes. Next, in another tank, a 0.5% hydrazine hydrate aqueous solution at 33°C was immersed for 0.5 minutes, and then rinsed with water. Next, in another tank, the pieces were immersed in a 1.5% hydrogen peroxide solution for 5 minutes, and then thoroughly rinsed with water. These Al alloy pieces were placed in a hot air dryer set at 67°C for 15 minutes to dry, and then wrapped in clean aluminum foil and stored.

[0051] [Experimental Example 9] (Adhesive joint between Al alloy thin plate and CFRP prepreg) There are two bonding methods for CFRP and thin metal sheets: the dry method and the wet method. The latter method provides better reproducibility of adhesive strength. Specifically, in addition to the lamination process of CFRP prepreg, an adhesive-coated aluminum alloy sheet is layered on top of the CFRP prepreg. The laminate is then heated under reduced pressure and pressure, and the aluminum alloy sheet is bonded to the CFRP prepreg while it hardens to form CFRP. The CFRP prepreg is made of plain weave CF. The CFRP prepreg was fabricated using a 0.5 mm thick NAT-treated A6061 aluminum alloy sheet (Example 8) coated on one side with a one-component epoxy adhesive, EW2040 (3M Japan Ltd., Tokyo, Japan), and then inserted into the laminate. The CFRP and aluminum alloy sheets were bonded using the wet method. The composite was then cut into 45 mm x 15 mm x 3.5 mm test pieces, each consisting of an A6061 aluminum alloy sheet and a CFRP thick sheet (see Figure 1). When the shear bond strength between the CFRP body and the A6061Al alloy thin plate bonded to this test piece was measured, the measured value was approximately 38-39 MPa at a temperature of 23°C. In other words, the maximum shear bond strength of bonded pairs (test pieces) made between CFRP plates using the latest type of CF (tensile strength approximately 6 GPa), or between such CFRP plates and NAT-treated metal, even with the obstacles caused by differences in linear expansion coefficients, is approximately 40 MPa.

[0052] However, when the composite of the present invention is used, for example, as a structural material for an aircraft, the shear joint strength (or shear adhesive strength) between the CFRP material and the high-strength metal material needs to be raised to the 60 MPa level. Instead of using CFRP alone as the base material on the CFRP material side, a high-strength metal thin plate (e.g., SUS304 steel, A6061 Al alloy, A2024 Al alloy) with a thickness of approximately 0.2 to 0.5 mm is used, with the surface bonded. Another type of thick metal plate is bonded to this CFRP with thin metal plate using a one-component epoxy adhesive. The metal thick plate piece bonded to the large CFRP thick plate main structural material serves as a connector for connecting to another metal structure with bolts and nuts, so it can be a small component even if it is thick. In other words, the bonding area between the composite and the connecting member is at most 25 cm of 50 mm x 50 mm. 2If the adhesive surface on the composite side is A6061Al alloy, the shear adhesive strength between the composite and the connecting member is 60 MPa (approximately 600 kg / cm) if it is the adhesive strength between metals. 2 ) and adhesive strength is 600kg / cm 2 ×25cm 2 However, as mentioned above, the NAT adhesive strength between the CFRP material and the A6061Al alloy thin plate is 40MPa, which is only about 10t. However, the adhesive surface between the A6061Al alloy and the CFRP body is 25cm 2 In fact, it is much larger. Therefore, by preparing a thin metal plate and bonding it to the CFRP body over a wide area, it is possible to amplify the relatively low adhesion of the CFRP material. A detailed explanation of this is provided in Patent Documents 10 and 12.

[0053] Furthermore, there are important conditions for the thin metal sheets to be surface-bonded to the CFRP material proposed in Patent Documents 10, 12, etc., and the above-mentioned amplification effect does not work on metals with low tensile strength or yield strength, so when a strong external shear force is applied, the thin metal sheet that should be bonded to the CFRP body is torn off by the adhesive force with the small metal connecting member (peeling and tensile fracture occur simultaneously). Specifically, when using an Al alloy thin plate as the thin metal plate, A5052Al alloy must be 0.8 to 1 mm thick or it will tear apart, which is thought to be problematic (it is too thick for a thin plate), and so it is thought that the stronger A5082Al alloy or A6061Al alloy are more suitable.The inventors also tested the A2024Al alloy, which has sufficient strength, and the even stronger SUS304 steel, but it is difficult to obtain a stable 0.5 mm thick duralumin material as a general-purpose product, and it seems that 0.25 mm thick SUS304 steel is suitable, which is difficult to obtain, so the inventors have decided that the 0.5 mm thick A6061Al alloy is the best thin metal plate material for bonding the CFRP cover.

[0054] In the present invention, the adhesive used to strongly bond (adhere) two high-strength materials together is a crystalline thermoplastic resin, not a one-component epoxy adhesive. The technology is also an injection joining technology. Therefore, the target surface of the composite of the CFRP material and A6061Al alloy described above is A6061Al alloy, and the required surface treatment methods are NMT5-8, Ano-5, and Ano-7 treatment methods, which have been proposed in prior art. Similarly, the surface treatment method to be applied to the other high-strength metal material is NMT5-8, Ano-5, Ano-7, etc. for duralumin materials such as A7075Al alloy, but is SNMT treatment for 64Ti alloy, SUS304 steel, etc.

[0055] [Experimental Example 10] (SNMT injection joining strength using Al alloy and injection joining resin) To integrate an aluminum alloy sheet onto one side of a CFRTP material, it is first necessary to create a resin sheet with an aluminum alloy sheet attached as the heat-sealing partner. Therefore, the polyamide resin "CM3506G50" and PEEK resin mentioned above were injection-bonded to A6061 aluminum alloy, and the shear bond strength between the metal and resin was measured. In short, the assumption was that the CFRTP was manufactured using typical polyamide resins such as PA66 and PEEK as the matrix resin.

[0056] Specifically, A6061 Al alloy was injection bonded with PEEK-based resin (a dry blend of 95% PEEK "90G" (manufactured by Victrex, headquartered in the UK) and 5% PEI "ULTEM 9075" (manufactured by SHPP Japan, LLC, headquartered in Tokyo, Japan)), and the shear bond strength between the metal and resin was measured. This assumes that the CFRTP was manufactured using PEEK as the matrix resin. The results are shown in Table 1. All shear bond strengths are based on ISO 19095. [Table 1]

[0057] [Experimental Example 11] (SNMT injection joining strength using high-strength metal and injection joining resin) Table 2 shows the bond strength values ​​between metal and resin in injection-bonded products made between various high-strength metal materials to be bonded to CFRP or CFRTP and the following two types of injection bonding resin. All showed high bond strengths exceeding 50 MPa. [Table 2]

[0058] Furthermore, when the aforementioned PPS resin "SGX120" is used as the injection resin, it has been found that the shear joint strength is approximately 40 MPa with the conventional injection joining technologies "NMT" and "New NMT." The injection joining technology "SNMT" used in this invention has always been found to have higher performance than "NMT" and "New NMT," and the shear joint strength of injection joined products between various SNMT-treated metals and "SGX120" is also approximately 40 MPa.

Claims

1. an Al alloy thin plate chemical conversion treatment step of chemically treating one surface of an Al alloy thin plate having a thickness of 0.3 to 0.8 mm for adhesion; a bonding step of bonding one surface of the Al alloy thin plate to a surface of a CFRP material to obtain a CFRP material with an Al alloy thin plate; a chemical conversion treatment step for injection joining in which a surface of a metal material and the other surface of the Al alloy thin plate are chemically treated for injection joining; an inserting step of inserting the metal material into an injection molding die with a gap of 1.0 to 5.0 mm between the surface of the metal material and the other surface of the Al alloy thin plate; and an injection step of injecting a heat-resistant crystalline thermoplastic resin for injection joining into the gap.

2. a metal thin plate-attached resin plate fixing step of injecting a crystalline thermoplastic resin onto one surface of an Al alloy thin plate having a thickness of 0.3 to 0.8 mm to fix the resin plate, thereby obtaining an Al alloy thin plate-attached resin plate; preparing a CFRTP sheet material having a matrix resin that is a main component resin contained in the crystalline thermoplastic resin; a hot press lamination step in which one surface of the CFRTP plate and the resin plate with the Al alloy thin plate are overlapped and brought into contact with each other, and inserted into a hot press mold for fusion lamination to obtain a thick CFRTP plate with the Al alloy thin plate; a chemical conversion treatment step for injection joining in which a surface of the metal material and the other surface of the Al alloy thin plate are chemically treated for injection joining; an inserting step of inserting the metal material into an injection molding die with a gap of 1.0 to 5.0 mm between the surface of the metal material and the other surface of the Al alloy thin plate; and an injection step of injecting the crystalline thermoplastic resin having heat resistance for injection joining into the gap.

3. 2. The method for producing a composite of CFRP and metal material according to claim 1, The bonding step includes: As a pretreatment, a chemical conversion treatment step for adhesive bonding is performed on one surface of the Al alloy thin plate; an Al alloy thin plate laminating step of laminating the one surface of the Al alloy thin plate on a surface of a laminate obtained by laminating CFRP prepregs, the Al alloy thin plate laminating step including a coating step of applying a heat-resistant one-component epoxy adhesive to the one surface; an adhesive curing step in which the laminate of the CFRP prepreg and the Al alloy thin plate is heated in an environment reduced in pressure to atmospheric pressure or less to adhesively harden the laminate; The other surface of the Al alloy thin plate in the injection joining chemical conversion treatment step and the chemically treated surface of the metal material are The injection joining chemical conversion treatment step is a surface treatment for forming a surface shape, chemical reactivity or surface physical properties suitable for the injection joining. A method for manufacturing a composite of CFRP and metal material, characterized by:

4. The method for producing a composite of CFRTP and a metal material according to claim 2 further comprises the steps of: The crystalline thermoplastic resin and the matrix resin contained in the CFRTP sheet material are similar thermoplastic resin compositions, and are resin compositions whose main components are resins that can be completely mixed when melted. A method for manufacturing a composite material in which a CFRP material and a metal material are integrated.

5. 5. A method for producing a composite material in which CFRP and a metal material are integrated according to claim 1, The aluminum alloy thin plate is one selected from A5052, A5083, and A6061 as specified in the Japanese Industrial Standards. A method for manufacturing a composite material in which CFRP and a metal material are integrated.

6. 5. A method for producing a composite material in which CFRP and a metal material are integrated according to claim 1, A method for manufacturing a composite integrating CFRP and a metal material, wherein the metal material is one selected from Al alloys A2014, A2017, A2024, and A7075 specified in the Japanese Industrial Standards, or one selected from general steel, stainless steel, and 64Ti alloy.

7. 5. A method for producing a composite material in which CFRP and a metal material are integrated according to claim 1, A method for producing a composite integrating CFRP and a metal material, characterized in that the crystalline thermoplastic resin is one selected from PPS-based resins, polyamide-based resins, and PAEK-based resins including PEEK.

8. 8. The method for producing a composite material integrating CFRP and a metal material according to claim 7, The method for manufacturing a composite integrating CFRP and metal material is characterized in that the PPS-based resin does not contain GF or has a GF content of 20% by weight or less, the polyamide-based resin does not contain GF or has a GF content of 33.3% by weight or less, and the PEEK or PAEK-based resin does not contain GF or is a mixed resin of PEEK and polyetherimide (PEI) resin in a mass ratio of 95:5 to 85:

15.

9. 9. A method for producing a composite material in which CFRP and a metal material are integrated according to claim 1, A method for manufacturing a composite integrating CFRP and a metal material, characterized in that the chemical conversion treatment of the Al alloy thin plate and the metal material is performed by treating them with a water-soluble amine compound such as triethanolamine or EDTA (4Na).

10. 10. A method for manufacturing a composite in which CFRP and a metal material are integrated, as set forth in claim 1, wherein the composite in which CFRP and a metal material are integrated is manufactured by the method for manufacturing a composite.

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